Patent Publication Number: US-2013227916-A1

Title: Waste packing system with fusion seal apparatus

Description:
The present U.S. patent application claims priority to European Patent Application No. 11 190 266.4, filed Nov. 23, 2011, the disclosure of which is incorporated herein by reference in its entirety. 
     The present invention is directed to a waste packaging system, a method of storing waste and to a film for use in this system and method. 
     A lot of waste products produce smells that are annoying to the environment. Examples are decayed food, kid nappies and cat litter. 
     In the prior art there are many films that could be used for protection from malodors. As it is well known in the art, the use of materials like EVOH, PVDC, polyacrylonitrile is recommended in order to not allow malodors escape from the container (e.g. bag or other configuration) and create an unpleasant atmosphere. 
     There are also a lot of known configurations of packing a certain length of film/e.g. 20 meters) in a compressed form (e.g. in a cassette). Examples of the representative cassettes are shown in U.S. Pat. No. 4,934,529 or U.S. Pat. No. 3,536,192. 
     Generally the cassette comprises a tubular core, casing wall, cassette bottom and lid. The film is stored in an area between tubular core, casing wall and cassette bottom in a compressed configuration. The flexible tubing is dispensed from the cassette. After the malodorous item is thrown into the bag the core or the lid is rotated and the flexible tube is twisted so that it closes as hermetically as possible the waste/environment area. To dispose the next diaper the user opens the lid and inserts the diaper. The previous pack is pushed downward and a new knot is formed by twisting the tube above the newly deposited diaper. Thus the device stores the diapers in a series of individually wrapped packages in the storage chamber, each package being separated from adjacent packages by twists in the tube. 
     Separation of one piece of flexible film from the next by means of a rotary knife is preferred. 
     In the prior art as a general rule the separation of each piece of the film in which the smelly item is contained from the next piece of the film is done with a twisting mechanism. This twist separates in a “hermetic” way the one piece from the other. 
     That is to say, it is a problem in the prior art techniques that the twist is never really hermetic. Odor molecules being extremely small have the capability to escape through the folds so the odor starts to be noticeable after a few days. There is still a need for a more hermetic way to isolate each individual pack with the next one. 
     Methods based on heat sealing have been proposed in the prior art as for example in EP 0 005 660. This concept is quite complicated as it uses sheaths to form discrete packages. The complex nature of this design makes it expensive to manufacture. 
     According to the prior art document U.S. Pat. No. 4,869,049, the use of electricity is to be avoided anywhere near babies therefore this approach has not been commercially successful. So, twisting is the preferred option for separating one pack from the next. 
     Heat sealing and cutting as means to separate each pack from the next is also an object of U.S. Pat. No. 6,516,588. In this reference there is no mention to the use of a low voltage battery. So, in general this method is not suitable enough as it involves electricity of high voltage and this is to be avoided for this sensitive application. Also, there is no reference to a low voltage battery. 
     Further, U.S. Pat. No. 6,516,588 does not refer to a suitable film that can be sealed efficiently and also through pleats and wrinkles (which are unavoidable during this kind of application). According to this application “the plastic tubing may be any plastic tubing known in the art” as described in col. 4 lines 30-31. 
     The present invention provides a safe and simple apparatus that is quick and easy to operate, that stores soiled nappies in flexible tubing in a very hygienic way so that they can be disposed collectively after a certain amount of time. It also provides a suitable plastic film to be used accordingly. 
     SUMMARY OF THE INVENTION 
     The present invention in one aspect is directed to a device comprising:
         1. A dispensing apparatus wherein a plastic film is stored.   2. A bin wherein a fusion seal apparatus is located.   3. A fusion seal apparatus containing sealing jaws and comprising a battery with a maximum voltage of 20V.   4. Where the movement of the sealing jaws is done manually by the rotation of an axis.       

     The battery may be rechargeable or non-rechargeable. Preferably, it is rechargeable. 
     Also another object of the present invention is a method of packing waste items by:
         1. Pulling out plastic film from a dispensing apparatus.   2. Putting a waste item in a suitable length of the film.   3. Closing hermetically the plastic film with the use of a fusion seal as defined above where the seal is between a part of the film and another part of the same or other film, where the sealed parts are put sequentially in a bin.       

     The fusion seal is preferably done with a fusion seal apparatus comprising a battery with a maximum voltage of 20V. 
     The present invention further describes a multilayer plastic film comprising at least:
         1. An outer layer comprising at least 50% per weight of polyethylene homopolymer or copolymer.   2. An internal layer comprising at least one oxygen barrier material.   3. An inner layer comprising at least 50% per weight polyethylene homopolymer or copolymer,
 
for use in the above apparatus and method.
       

     DEFINITIONS 
     In this application the following definitions are used: 
     The term “waste” refers to any receptacle that is useless and has to be disposed of properly. For example, the term waste includes diapers or other dirt. 
     The term “dispensing apparatus” refers to any apparatus where the film is stored before the application process. Examples are cassettes or reels. 
     The term “cassette” refers to any container wherein the film can be put. Often the film is in compressed form. The cassette is usually plastic and circular but other configurations may be possible. 
     The term “fusion seal” refers to the sealing of film by melting. A different kind of seal is by twisting the plastic film or by used an adhesive (in this latter case a kind of seal is made by pressure alone). 
     The term “bin” refers to a container where many waste packs are put one after the other. Each pack comprises a portion of the sealed film and of course the waste inside. 
     The term “film” refers to a flat or tubular flexible structure of thermoplastic material. 
     The term “voltage” between two points refers to the electrical driving force that could determine an electric current between these points. 
     The term “battery” refers to one or more electrochemical cells that convert stored chemical energy to electrical energy. 
     The term “rechargeable” refers to batteries that are designed in a way to be recharged and used multiple times. 
     The term “multilayer” refers to a film comprising 2 or more layers. 
     The phrase “longitudinal direction” or “machine direction” herein abbreviated “MD” refers to a direction along the length of the film. 
     The phrase “outer layer” refers to the film layer which comes in immediate contact with the outside environment (atmosphere). 
     The phrase “internal layer” as used herein refers to a film layer located between the outer and the inner layer of the multilayer film. It is not in contact with the atmosphere or the good to be packaged and usually comprises an oxygen barrier material. 
     The phrase “inner layer” refers to the film layer that comes in direct contact with the product packed. This is also called “sealing layer” as this layer must be hermetically sealed in order to protect the product from ingress of air. 
     As used herein, the term “homopolymer” refers to a polymer resulting from polymerization of a single monomer. 
     As used herein, the term “copolymer” refers to a polymer resulting from polymerization of at least two different polymers. 
     As used herein, the term “polymer” includes both above types. 
     As used herein, the term “polyolefin” refers to any polymerized olefin, which can be linear, branched, cyclic, aliphatic, substituted or unsubstituted. More specifically, included in the term polyolefin are homopolymers of olefin, copolymers of olefin, copolymers of an olefin and a non olefinic comonomer (such as ester) etc. 
     Specific examples include polyethylene homopolymer, polypropylene homopolymer, polybutene homopolymer, ethylene alpha olefin copolymer, propylene alpha olefin copolymer, butene alpha olefin copolymer, ionomer, ethylene ester copolymer etc. 
     As used herein the term “polyethylene” identifies polymers consisting essentially of the ethylene repeating unit. The ones that have a density more than 0.940 are called high density polyethylene (HDPE), the ones that are have less than 0.940 are low density polyethylene (LDPE). 
     As used herein the phrase “ethylene alpha olefin copolymer” refers to polymers like linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), very low density polyethylene (VLDPE), ultra low density polyethylene (ULDPE), metallocene catalyzed polymers and polyethylene plastomers and elastomers. 
     As used herein the term “homogeneous ethylene alpha olefin copolymers” refer to ethylene alpha olefin copolymers having a molecular weight distribution less than 2.7 as measured by GPC. Typical examples of these polymers are AFFINITY from DOW or Exact from Exxon. 
     As used herein the phrase “styrene polymers” refers to styrene homopolymer such as polystyrene and to styrene copolymers such as styrene-butadiene copolymers, styrene-butadiene-styrene copolymers, styrene-isoprene-styrene copolymers, styrene-ethylene-butadiene-styrene copolymers, ethylene-styrene copolymers and the like. 
     As used herein the phrase “ethylene methacrylate copolymers” refers to copolymers of ethylene and methacrylate monomer. The monomer content is less than 40%. 
     As used herein the phrase “ethylene vinyl acetate copolymer” or EVA refer to copolymers of ethylene and vinyl acetate. 
     As used herein the phrase “ethylene ester copolymer” includes any polymer made from ethylene and ester monomers. It is obvious that this term includes EVAs, EMAs and other polymers. 
     As used herein the term “oxygen barrier polymer” refers to polymers which have the property to limit the passage of oxygen through a film or a layer comprising the polymer. Common materials, are EVOH, PVDC or polyamide. Those polymers usually are comprised in the internal layer of the multilayer film. 
     As used herein, the term EVOH refers to saponified products of ethylene vinyl ester copolymers. The ethylene content is typically in the range of 25 to 5o % per mol. All the later references to EVOH ethylene content will be in % per mol. 
     As used herein the term PVDC refers to a vinylidene chloride copolymer wherein a major amount of the copolymer comprises vinylidene chloride and a minor amount of the copolymer comprises one or more monomers such as vinyl chloride and/or alkyl acrylates and methacrylates. 
     As used herein the term “polyamide” refers to homopolymers and copolymers. Polyamide 6, polyamide 66, polyamide 12, polyamide 6/66, polyamide 6/12, polyamide elastomers, MXD polyamides and other copolymers are specifically useful for the invention. 
     As used herein the term “polyester” refers to polymers comprising terephthalate units. Examples of polyesters are PET (polyethylene terephthalate), PBT (polybutylene terephthalate), polyester elastomer (block copolymer comprising ester or ether units), PTT and other similar polymers. 
     As used herein, the term “ionomer” comprises the copolymers of ethylene and methacrylic or acrylic acid being metal neutralized. An example of such material is Surlyn from Dupont. 
     As used herein, the term “polypropylene” refers to polymers incorporating propylene structural units. Examples of these, are homo polypropylenes, random copolymers of propylene and ethylene, block copolymers of propylene and ethylene, copolymers or blends of propylene and rubber (such as blends of polypropylene and ethylene propylene rubber), propylene ethylene alpha olefin terpolymers and others. 
     These polymers may be isotactic, syndiotactic or atactic. Isotactic is preferred. 
     In line with the above definition, it is noted that for the purposes of the present invention, the term “inner layer” is to be regarded as an additional outer layer of the multilayer film, which is in direct contact with the item to be packaged (i.e. an outer layer of the film which is located on the inside after a packaging process, not exposed to the environment). 
     As used herein the term “substantially non-resilient material” refers to materials or material compounds comprising at least 40% per weight inorganics like calcium carbonate, titanium dioxide, wollastonite, mica, glass fibers, dolomite and the like. The rest percentage per weight can be polyethylene, polypropylene, styrene polymer or other thermoplastic material. 
     As used herein the term “manual” means the movement due to human physical force as opposed to automatic movements which do not need the intervention of the human force. 
     All measurement methods mentioned herein are readily available for the skilled person. For example, they can be obtained from the American National Standards Institute on the worldwide web at www.webstore.ansi.org. 
     All percentages are based on weight per weight ratio, except when otherwise stated. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention in one aspect is directed to a device comprising
         1. A dispensing apparatus wherein a plastic film is stored.   2. A bin wherein a fusion seal apparatus is located.   3. A fusion seal apparatus containing sealing jaws and comprising a battery with a maximum voltage of 20V.   4. Where the movement of the sealing jaws is done manually by the rotation of an axis.       

     The battery may be rechargeable or non-rechargeable. Preferably, it is rechargeable. 
     Also another object of the present invention is a method of packing waste items by:
         1. Pulling out plastic film from a dispensing apparatus.   2. Putting a waste item in a suitable length of the film.   3. Closing hermetically the plastic film with the use of a fusion seal where the seal is between a part of the film and another part of the same or other film, where the sealed parts are put sequentially in a bin.       

     The fusion seal is preferably done with a fusion seal apparatus comprising a battery with a maximum voltage of 20V. 
    
    
     
       DESCRIPTION OF THE FIGURES 
         FIGS. 1 and 2  show a top view and a bottom view of the mechanical rotation mechanism of the present invention. 
         FIGS. 3 and 4  each show section views of the mechanical rotation mechanism of the present invention. 
     
    
    
     DISPENSING APPARATUS 
     A dispensing apparatus of the present invention preferably has the form of a cassette. Nevertheless, other dispensing apparatus are also possible in which a cassette is not used. For example the film can be wound in the form of a mini roll around a paper core. Alternatively, two such mini rolls may comprise the film in such a way that the film wound in the first mini roll will heat seal to the film that is wound in the second mini roll. 
     Cassette 
     In a preferred embodiment the cassette useful for the invention is circular in shape. Preferably it is made by plastic, e.g. polypropylene. 
     It is also possible to be manufactured from other means more friendly to the environment such as paper, biodegradable plastic or non-biodegradable plastic where a percentage of “degrading” additives have been added. 
     Generally, the cassette comprises a tubular core, casing wall (see cassette bottom and lid). The film is stored in an area between tubular core, casing wall and cassette bottom in a compressed configuration. The flexible tubing is dispensed from the cassette. 
     In a further preferred embodiment of the invention the cassette comprises a malodor counteractant useful for absorbing, adsorbing or masking the smell of the waste. 
     In a preferred embodiment of the invention the film inside the cassette the film is in compressed configuration. 
     Seal Apparatus 
     A preferred version of the sealing apparatus of the present invention is an apparatus capable of impulse sealing. An impulse sealer is a jaw sealer backed with resilient silicone rubber. Electric current flows through Nichrome ribbon stretched over one over one or both surfaces and covered with high temperature release film and fabric. 
     Another preferred version of the seal apparatus is wire or knife sealing. According to this method a hot wire or knife seals and cuts the film. 
     Other methods for the seal apparatus that could be used according to the invention include bar sealing, band sealing, ultrasonic sealing, friction sealing, gas sealing, contact sealing, hot melt sealing, pneumatic sealing, dielectric sealing, magnetic sealing, induction sealing, radiant sealing, solvent sealing, etc. For these methods please refer to the Wiley Encyclopedia of packaging technology, edition 1997. 
     In a preferred embodiment of the invention the electric current necessary for the heat sealing and fusion is provided through a rechargeable battery. The voltage of the rechargeable battery is preferably equal or less than 20 V, even more preferably less than 16 V, even more preferably less than 12V. 
     In a preferred version of the invention the temperature for the heat seal is less than 100° C., preferably less than 90° C., preferably less than 80° C. 
     In a further preferred version of the invention, the sealing time is less than 5 seconds, more preferably less than 3 seconds, more preferably less than 1 second. 
     In a further preferred version of the invention, the cutting of each pack to the previous one is done simultaneously with the sealing by the use of a wire/knife configuration. In another version, there is no cutting. In this case all the packs are put together inside the bin in a single line. 
     The use of a rechargeable battery of low voltage assures a safe procedure that is more user friendly than household electricity. 
     Another alternative possibility of the invention is the use of more than one heat seal to make an individual pack. So two, three or four seals are possible. 
     In the case of three or four seals, the film should be in a “single sheet” configuration instead of “flexible tubing”. 
     Movement of the Sealing Jaws 
     The mechanism activates with manual rotation of axis  1 . 
     The activation of axis  1  can take place by a steering wheel, a lever or an electric motor. 
     On the axis  1  which rotates freely with its ends stabilized on the frame  6  two gears ( 2 ) are put on either side. 
     The gears ( 2 ) transfer the movement to the gears ( 3 ) and these to the gears ( 4 ). 
     The gears ( 3 ) and ( 4 ) are put on the frames ( 7 ) and ( 8 ) which rotate freely with their ends firmly adjusted on frame ( 6 ). 
     The sealing bars ( 5 ) are firmly adjusted on frames ( 7 ) and ( 8 ). 
     The anti-clockwise movement of axis ( 1 ) provokes, due to the involvement of gears ( 2 ), ( 3 ) and ( 4 ) a change of position of the sealing bars from the horizontal position (see  FIG. 1 ) to the vertical position(see  FIG. 2 ) where they come in touch to each other. 
     The stiffness of frames ( 7 ) and ( 8 ) and the set of the pairs of gears ensure that the sealing bars ( 5 ) are perfectly parallel during their closing process (sealing). 
     When the sealing bars come in contact a microswitch is energized and electric current (produced by battery) passes through the sealing wires. The sealing time is controlled through a timer. The sealing time is pre-determined. After the passing of the sealing time, the sealing bars return to their original position. 
     Film Characteristics 
     In the prior art, a lot of possible film configurations either monolayer or multilayer have been proposed. The basic characteristics a film should have in order to be used in the particular case are:
         1. Barrier to odors.   2. To have the proper deadfold properties (non-resilient) so that is compressed efficiently in the cassette if a cassette is used as a dispensing apparatus.   3. To have sufficient mechanical properties (e.g. tensile strength at break, elongation).   4. To have sufficient sealing properties as to be sealed with a low voltage rechargeable battery. Also the sealing properties must be sufficient to seal through wrinkles or pleats that are inevitable for this kind of application.       

     LIST OF REFERENCE SIGNS 
     
         
           1  axis 
           2  gear 
           3  gear 
           4  gear 
           5  sealing bar 
           6  frame 
           7  frame 
           8  frame