Abstract:
A multiple layered bag comprising such materials that one surface of the bag degrades when it comes in contact with water, for example polyvinyl alcohol, while the other surface is water resistant, such that the bag can be used to collect moist materials, for example pet excrement, without exposing the bag handler to those moist materials, yet when the everted bag is subjected to an aqueous environment, with the liquid degradable surface exposed to the aqueous environment, all the components of the bag degrade. The bag degrades such that the remaining components of the bag and the contents thereof are easily flushed down the toilet.

Description:
This application claims the benefit of provisional application Serial No. 60/165,912, filed Nov. 17, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     Responsible pet ownership has come to constitute more than just feeding and walking one&#39;s dog. Pet excrement deposited in public places is not only aesthetically unappealing, but poses numerous health risks and can adversely effect the environment. Exposure to pet excrement can result in  E. coli  ( Escherichia coli ) bacteria or roundworm infestation; and  E. coli  bacteria and roundworms can survive in tainted soil long after the excrement has degraded. Further, improperly disposed of pet excrement can be transferred into our waterways by storm water, potentially leading to water pollution that can reach hazardous levels and threaten aquatic life. 
     What was once considered to be exclusively an urban concern is no longer isolated to that context, as greater public awareness of the health concerns created by publicly deposited pet excrement, and laws and ordinances created in response thereto, have resulted in increased numbers of pet owners who responsibly “clean up” after their pets. Unfortunately, “cleaning up” after one&#39;s pet is inconvenient and requires special considerations. Specifically, the actual process of collecting pet excrement can be discomforting and unsanitary; the excrement itself cannot be discarded in just any trash receptacle, due to the obvious differences between excrement and typical garbage items; and the materials used to collect pet excrement, such as slow or non-degrading plastic bags, often introduce other environmental issues. The present invention resolves the aforementioned issues by minimizing the personal discomfort and unsanitary circumstances associated with collecting pet excrement, while allowing for convenient and environmentally conscious disposal of the excrement in an ordinary toilet. 
     The present invention relates to: Biodegradable bags that will degrade when immersed in an aqueous environment but will resist degradation when only the exterior surface of the bag comes in contact with liquid; A process for manufacturing biodegradable bags that will degrade when immersed in an aqueous environment but will resist degradation when only the exterior surface of the bag comes in contact with liquid; and A method for using biodegradable bags that will degrade when immersed in an aqueous environment but will resist degradation when only the exterior surface of the bag comes in contact with liquid to pick up pet excrement and dispose of such excrement in an ordinary toilet. 
     U.S. Pat. No. 5,679,421 describes a biodegradable bag of two ply construction, comprising an inner layer of specific thermoplastic materials and an outer paper layer. The materials are all biodegradable and the thermoplastic materials selected are purportedly resistant to the passage of liquid there through. Of the thermoplastic materials described, those that successfully resist the passage of water there through do not degrade in an aqueous environment and those that are degradable in an aqueous environment do not resist the passage of water there through and are hence inappropriate for using to pick up pet excrement. 
     U.S. Pat. No. 4,902,283 describes an absorbable cleaning mitt for wiping babies that allows the user to clean a baby with the absorbing cotton exterior, while completely protecting the user&#39;s hand from that which is being cleaned off of the baby. However, the described mitt is not biodegradable. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a multiple layered bag of such materials that one surface of the bag degrades when it comes in contact with water, while the other surface is water resistant, such that the bag can be used to collect moist materials, for example pet excrement, without exposing the bag handler to those moist materials, yet when the everted bag is subjected to an aqueous environment, with the liquid degradable surface exposed to the aqueous environment, all the components of the bag degrade. The bag degrades such that the remaining components of the bag and the contents thereof are easily flushed down the toilet. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     By way of further explanation of the invention, exemplary embodiments of the invention will now be described with reference to the accompanying drawings, in which: 
     FIG. 1 is a cross-section of a multiple layered bag, which embodies the invention; 
     FIG. 2 is a pictorial view of a multiple layered bag with a hand inserted therein; and 
     FIG. 3 is a pictorial view of an everted multiple layered bag containing pet excrement. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The apparatuses shown in the accompanying drawing and described below are examples that embody the invention. It should be noted that the scope of the invention is defined by the accompanying claims, and not necessarily by specific features of exemplary embodiments. 
     FIG. 1 shows a multiple layered bag  10 , having an interior layer  13  made of water-soluble plastic material, like polyvinyl alcohol, an intermediary layer  12  made of water retardant material, like silicone, and an exterior layer  11  made of biodegradable paper, like kraft paper. 
     Polyvinyl alcohol resins are available in a number of grades of degree of hydrolysis and molecular weight. The degree of hydrolysis and the molecular weight influence the solubility of polyvinyl alcohol resins, but the degree of hydrolysis is by far the more significant of the two variables. For quick dissolution in cold water, resins having a degree of hydrolysis of up to 88% are typically used. Resins having a degree of hydrolysis of 96% to 99.5% are considered to be hot water-soluble only. Resins having a degree of hydrolysis of 88% to 95% can be considered as intermediate in solubility characteristics or “warm water-soluble”. By using combinations of these resins in a water-soluble plastic material formulation, varying degrees of water solubility at given temperatures can be achieved. Variations in the molecular weights of the resins can also influence the water solubility. As such, the formula of the polyvinyl alcohol resin used for the multiple layered bags is modified or selected so that the molecular weight and/or the degree of hydrolysis of the polyvinyl alcohol resin result in the onset of disintegration following exposure to an aqueous environment being preferably delayed for a period ranging from five minutes to one hour or thirty seconds to two hours. At a minimum, the onset of disintegration should be delayed at least thirty seconds to give user time to dispose of the bag and its contents after picking up a moist substance. At the outside, the delay should be no greater than two hours to assure that disintegration begins within a reasonable time after disposal. 
     The bag sheet material can be made by spraying the water retardant material  12  on one surface of the water-soluble plastic material  13 , then laminating or pressure adhering the biodegradable paper  11  on the water retardant material  12  covered surface of the water-soluble plastic material  13 . Selected areas of two sheets of the multiple layered bag material are joined together, to form a bag construction  10  having an interior layer  13  made of water-soluble plastic material and an exterior layer  11  made of biodegradable paper. Alternatively, selected areas of one sheet of the multiple layered bag material are joined together, to form a bag construction  10  having an interior layer  13  made of water-soluble plastic material and an exterior layer  11  made of biodegradable paper. 
     Alternatively, the bag sheet material can be made by spraying the water retardant material  12  on one surface of the biodegradable paper  11 , then laminating, pressure adhering, or spraying the water-soluble plastic material  13  on the water retardant material  12  covered surface of the biodegradable paper  11 . Selected areas of two sheets of the multiple layered bag material are joined together, to form a bag construction  10  having an interior layer  13  made of water-soluble plastic material and an exterior layer  11  made of biodegradable paper. Alternatively, selected areas of one sheet of the multiple layered bag material are joined together, to form a bag construction  10  having an interior layer  13  made of water-soluble plastic material and an exterior layer  11  made of biodegradable paper. 
     As another alternative, the bag sheet material can be made by creating one layer composing both the water retardant material  12  and the biodegradable paper  11 , by adding the water retardant material  12 , a resinous or starch-like material, during the slurry phase of the biodegradable paper  11  manufacture, then laminating, pressure adhering, or spraying the water-soluble plastic material  13  on the water retardant biodegradable paper  12  and  11 . Selected areas of two sheets of the multiple layered bag material are joined together, to form a bag construction  10  having an interior layer  13  made of water-soluble plastic material and an exterior layer  11  made of biodegradable paper. Alternatively, selected areas of one sheet of the multiple layered bag material are joined together, to form a bag construction  10  having an interior layer  13  made of water-soluble plastic material and an exterior layer  11  made of biodegradable paper. 
     FIG. 2 shows a multiple layered bag  10  with a hand  20  inserted in the multiple layered bag in such a manner that the hand comes in contact with the water-soluble plastic material interior layer  13  and the exterior biodegradable paper layer  11  covers at least a portion of the bag surface that covers the palmar side of the multiple layered bag  10 . The palmar side of the hand  20  is covered by all layers  11 ,  12 , and  13  of the bag  10  so that when the bag  10  covered palmar side of the hand  20  comes in contact with waste materials for disposal  30 , such as pet excrement, the biodegradable paper layer  11  acts to protect the hand  20  from the unpleasant feeling of coming into contact with the waste material  30  and the water retardant layer  12  prevents physical contact between the hand  20  and any components of the waste material  30 , including liquids. Once the palmar side of the bag  10  protected hand  20  is used to collect the waste material, the hand  20  is removed from the bag  10  in such a manner that the bag  10  is everted, leaving the waste material  30  inside the everted bag  10 , with the water-soluble plastic material layer  13  now the exterior layer. 
     FIG. 3 shows a multiple layer bag  10  that has been everted, contains waste material  30 , and is being carried by a hand  20 . As the waste material  30  has only come in contact with the biodegradable paper layer  11  and not the water-soluble plastic layer  13 , the user can safely hold the everted bag  10  by the water-soluble plastic layer  13 , such that the hand does not come in contact with the waste material  30  or the biodegradable paper layer  11 , which has come in contact with the waste material  30 . The user can safely carry the everted bag  10  to an ordinary toilet, where the everted bag  10  can be discarded into the toilet and the aqueous environment degrades the water-soluble plastic layer  13  and the biodegradable paper layer  11 , leaving the water retardant layer  12  with nothing to be attached to, and hence broken into molecular sized particles which can be flushed down the toilet along with the waste material  30  and the other components of the degraded bag  10 . 
     The present invention describes biodegradable bags, processes for making such biodegradable bags, and methods, for using such biodegradable bags to collect waste materials, such as pet excrement, and dispose of such bags containing waste material in an ordinary toilet. However, it will be appreciated by those skilled in the arts pertaining thereto, that the present invention can be practiced in various alternate forms and configurations. Further, the previously detailed descriptions of the preferred embodiments of the present invention are presented for purposes of clarity of understanding only, and no unnecessary limitations should be implied therefrom. All appropriate mechanical and functional equivalents to the above, which may be obvious to those skilled in the arts pertaining thereto, are considered to be encompassed within the claims of the present invention.