WO1999064087A9

WO1999064087A9 - Degradable container

Info

Publication number: WO1999064087A9
Application number: PCT/US1999/013298
Authority: WO
Inventors: Baosheng Lee; Feng Qin; Nigel J Flynn; Travis W Honeycutt; Robert S Woody
Original assignee: Isolyser Co; Baosheng Lee; Feng Qin; Nigel J Flynn; Travis W Honeycutt; Robert S Woody
Priority date: 1998-06-12
Filing date: 1999-06-11
Publication date: 2000-10-05
Also published as: WO1999064087A1; AU4439499A

Abstract

A method of disposing of a sealed container and its contents comprising contacting the container with a disposal liquid at a temperature and for a time sufficient to lessen the structural integrity of the container, and to cause the container to release the contents. Also provided are a degradable suction container comprising a polymer that softens sufficiently when immersed in a liquid below 100 °C to lessen the structural integrity of the container, and to cause the container to release its contents, and a degradable suction container comprised of a material that dissolves or disperses in a disposal liquid sufficiently to cause the container to release its contents.

Description

DEGRADABLE CONTAINER

FIELD OF THE INVENTION

The present invention relates to degradable containers In particular, the present invention provides containers that can be disposed of, along with their contents, by contacting them with an appropπate disposal liquid

BACKGROUND OF THE INVENTION Management of infectious wastes is a persistent problem at medical facilities, and many attempts have been made to reduce or eliminate the πsk of human infection from such wastes In one example, the infectious waste is placed in a container, and the mateπal within the container is treated to kill or deactivate substances capable of causing infection The deactivated mateπal is then disposed and the container sterilized using commonly known methods. Alternatively, the entire container can be disposed after one use However, these methods pose πsks to the workers who manage the waste, and also increase disposal costs through landfilhng or incineration

SUMMARY OF THE INVENTION The invention provides a container that is specially designed to manage infectious wastes safely and efficiently The container is constructed of a mateπal that loses its structural mtegπty when immersed in a disposal liquid, causing the contents of the container to be released into the disposal liquid The container can lose its structural integrity by dissolving, dispersing, or simply softening enough to allow release of the container's contents The container, or what remains of it, can then be retπeved from the disposal liquid and separately disposed

Thus, in one aspect, the invention provides a method of disposing of a sealed container and its contents compπsing contacting the container with a disposal liquid at a temperature and for a time sufficient to lessen the structural mtegπty of the container, and to cause the container to release the contents

In another embodiment the invention provides a degradable suction container compπsing a polymer that softens sufficiently when immersed in a liquid below 100 °C to lessen the structural mtegnty of the container, and to cause the container to release its contents. In still another embodiment the invention provides a degradable suction container comprised of a material that is dissolvable or dispersible in a disposal liquid.

Additional advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. DESCRIPTION OF THE FIGURES

The accompanying drawing, which is incorporated in and constitutes a part of this specification, illustrates an embodiment of the invention and, together with the description, serves to explain the principles of the invention.

Figure 1 is a container constructed in accordance with one aspect of the invention.

Figure 2 is a disposable suction container of the design disclosed in U.S. Patent No. 5,672,162, in accordance with another aspect of the invention.

DETAILED DESCRIPTION OF THE INVENTION The present invention may be understood more readily by reference to the following detailed description of the preferred embodiments of the invention. Definitions and Use of Terms

Before the present articles and methods are disclosed and described, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. It must be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

Ranges are often expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value is another embodiment.

References in the specification and the concluding claims to parts by weight of a particular element or component in a composition or article, denote the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, for example, in a compound containing 80 parts by weight of components X and/or Y and

20 parts by weight component Z, X and/or Y will be present at a weight ratio of 80 and

Z will be present at a weight ratio of 20, and are present in such ratio regardless of whether additional components are contained in the compound.

A residue of a chemical species, as used in the specification and concluding claims, refers to the moiety that is the resulting product of the chemical species in a particular reaction scheme or subsequent formulation or chemical product, regardless of whether the moiety is actually obtained from the chemical species. Thus, for example, an acrylic acid residue in an ethylene-acrylic acid copolymer refers to one or more CH₂

CHCOO units in the copolymer, regardless of whether acrylic acid was used to prepare the copolymer.

As used herein, the term "disposal liquid" is the liquid in which the container is contacted or immersed prior to disposal. Preferably, the disposal liquid is comprised primarily of a material that may be released into a drain, sewer or septic tank, such as, water. The disposal liquid may also contain pH adjusting agents that help disinfect the container's contents, help to degrade the container, or prevent the container from adhering to a disposal vessel.

As used herein, the term "degradable" refers to a material that, upon contact with a disposal liquid under appropriate conditions, loses structural integrity or shrinks in volume. The degradation can occur by softening the material, or dispersing or dissolving the material.

As used herein, the term "degradable container" is defined as a vessel used to collect waste material obtained, for example, in a medical procedure. The container must be made of a degradable material, or must contain one or more parts made from a degradable material, to cause the container to degrade and release its contents under appropriate disposal conditions. The container will typically comprise a vessel for receiving wastes, and a lid, and either the vessel or the lid, or both, can be degradable.

As used herein, the term "degradable suction container" is a species of "degradable containers," and is defined as a vessel used to collect aspirated material obtained by suctioning in conjunction with, for example, a medical procedure. Preferably, the degradable suction container will fit into a rigid outer casing, and comprise a liner and a lid and/or closure means whereby the contents of the suction container may be sealably fixed. Even more preferably, the suction container will contain a liner bounding a contained volume for receiving materials from a source external to the liner, an inlet port through the lid for introducing the materials into the contained volume and a means for generating suction at the inlet port. Non-limiting examples of suction containers are provided in U.S. Patent Nos. 5,584,825 and 5,672,162, the disclosures of which are incorporated in their entireties by this reference. As used herein, the term "hot" refers, in separate embodiments, to temperatures above 40 °C, 50 °C, 60 °C, 75 °C, 90 °C, 100 °C, 1 10 °C, and 125 °C.

As used herein, the term "alkaline" refers, in separate embodiments, to pH values above 7.0, 8.0, 9.0, 10.0, and 11.0.

As used herein the term "sealed" is relative, and means sufficiently sealed to prevent a material release from the contents of a sealed container. The degree to which a container must be sealed to prevent "material" release of the container's contents will depend on how the container is handled, and the degree to which the contents are hazardous.

As used herein, the term "ethylene-(meth)acrylic acid copolymer" means a copolymer of ethylene and acrylic acid, a copolymer of ethylene and methacrylic acid, a mixture of copolymers of acrylic and methacrylic acids or teφolymers of acrylic acid, methacrylic acid and ethylene. As further used herein, the term "(meth)acrylic acid" means acrylic acid, methacrylic acid or mixtures thereof.

As used herein, the term "ionomer" means a copolymer of ethylene and (meth)acrylic acid, wherein the copolymer has been neutralized with a metal cation. Ethylene-(meth)acrylic acid ionomers are typically obtained by partially reacting an ethylene-(meth)acrylic acid copolymer with a metallic salt to form ionic crosslinks between the (meth)acrylic acid moiety residues within a copolymer chain or between neighboring chains. The cationic charge of the metallic salt partially neutralizes the acid residues of the copolymer. Preferably, about 50 to 60% of the residues of acidic moieties are neutralized; more preferably, about 55% of the acidic moiety residues are neutralized. Suitable cations for neutralizing the acidic moieties are Na⁺, K⁺, Li⁺, Cs^τ, Rb⁺, Hg⁺, Cu⁺, Be²⁺, Mg²⁺, Ca²⁺, SΛ Ba²⁺, Cu²⁺, Cd²⁺, Hg²⁺, Sn²⁺, Pb²⁺, Fe²⁺, Co^2τ, Ni²⁺, Zn²⁺, Al³⁺, Sc³⁺, Fe³⁺ and Y³⁺. Preferred cations include sodium, lithium and potassium ions.

As used herein, the term "dissolvable" refers to a material that, upon contact with a disposal liquid under appropriate conditions, dissolves partially or completely into the liquid to form a solution. As used herein, the term "dispersible" refers to a material that is subject to structural weakening and breakup when contacted with a disposal liquid under appropriate conditions. The appropriate conditions for dissolution or dispersal may consist of one or more of temperature, pH, liquid type and composition or any other parameter that may be disclosed herein. Discussion

In one embodiment the invention provides a method of disposing of a sealed container and its contents comprising contacting the container with a disposal liquid at a temperature and for a time sufficient to lessen the structural integrity of the container, and to cause the container to release the contents. In another aspect the invention provides a container comprising a polymer that softens sufficiently when immersed in a liquid below 100 °C to lessen the structural integrity of the container, and to cause the container to release its contents. In a further embodiment the invention provides a degradable suction container comprised of a material that is dissolvable or dispersible in a disposal liquid. In another aspect, the invention provides a method of disposing of a suction container comprising contacting the container with a disposal liquid for a time sufficient to dissolve or disperse the container.

In one embodiment, the disposal liquid is a hot aqueous solution, with hot as described above. In another embodiment the disposal liquid is an alkaline liquid, with alkaline as described above. In still another embodiment the disposal liquid is hot and alkaline. The methods can be practiced at elevated pressures, for example, pressures above 1 atmosphere, 2 atmosphere, and even 5 atmosphere, depending upon the degradation characteristics of the container, and the other processing conditions. The disposal liquid is preferably of a temperature sufficient to deactivate or kill any potentially infectious materials present in the container.

In one example, the degradable container to be disposed of is introduced into the disposal liquid at a suitable temperature or pH. The mixture is preferably agitated for greater than 2 or 5 minutes, and preferably less than 30 or 200 minutes. For example, disposal of containers of the compositions disclosed herein could be accomplished in a hot water bath, such as a washing machine dedicated solely to degrading articles by the process of this invention. If the container completely dissolves or disperses, then the dissolved or dispersed material can be discharged with the disposal liquid. If anything remains of the container, then it can be retrieved and either reused or separately disposed. Thus, in another embodiment of the invention, the method of disposing of a degradable container further comprises retrieving the degraded container, and releasing the contents into a drain, sewer, or septic tank.

The container can take many forms. For example, the container can be constructed entirely of the degradable material, or only part of the container can be constructed of the degradable material, as long as the structural integrity of the container is compromised sufficiently during contact with the disposal liquid to cause the container to release its contents.

Thus, in one embodiment the invention provides a sealed container that comprises a lid that preferably seals an opening of the container, wherein the lid loses its structural integrity when contacted with a disposal liquid at a sufficient temperature and for a sufficient time, and allows the contents of the container to be released through the opening.

In another embodiment, the container comprises a degradable liner that degrades in an appropriate disposal liquid. The liner material can be rigid or soft. The liner may be sealably attached to a closure such as a lid. The liner and/or lid may be degradable. The liner-lid combination may be inserted into a rigid outer casing, and later removed from the casing and immersed in an appropriate disposal liquid, so that the container and its contents are simultaneously disposed. The rigid outer casing may optionally be re-used or disposed of using conventional methods. Thus, in another embodiment the sealed container comprises a liner and a lid, the lid preferably seals an opening of the liner, and the liner loses its structural integrity when contacted with a disposal liquid at a sufficient temperature and for a sufficient time, and allows the contents of the container to be released.

A prefeπed degradable material is poly( vinyl alcohol), which is preferably post- drawn and heat annealed. The polyvinyl alcohol is preferably highly crystallized in order to increase the temperature at which it becomes soluble in an aqueous solution. The polyvinyl alcohol preferably has a degree of crystallinity above 15 or 30%, and more preferably above 50%. Moreover, the polyvinyl alcohol is preferably is at least 95%) hydrolyzed or saponified, and more preferably greater than 98%.

The commercial product Vinex^® 1003 (Air Products Company, Allentown, PA), a polyvinyl alcohol that has been highly crystallized by post-drawing and that has been plasticized with polyethylene glycol and/or glycerine, is particularly useful for practicing this invention. It may be molded, formed, or extruded at about 210 °C without disintegration to produce a container that solubilizes only at temperature of 37 °C or greater in water.

In one embodiment, polyvinyl acetate homopolymer may be blended with polyvinyl alcohol in the weight range of from about 1 :99 to about 1 :9 (parts polyvinyl acetate by weight: parts polyvinyl alcohol) to produce a thermoplastic material that typically can be plasticized with polyethylene glycol and then molded, formed or extruded at 200 to 220 °C without disintegration. The polyvinyl alcohol and polyvinyl acetate blend may preferably contain from about 0.001 to 5.0% by weight of a plasticizer. In yet another embodiment, the plasticizer is polyethylene glycol or glycerine.

Another preferred degradable material is one which is alkaline dissolvable or dispersible, such as an ethlyene-(meth)acrylic acid copolymer. Preferably, the copolymer is comprised of 10-30 % by weight (meth)acrylic acid residues, and, even more preferably, the copolymer is comprised of 15-25 % by weight (meth)acrylic acid residues. Examples of ethylene-(meth)acrylic acid copolymers that are particularly useful in practicing this invention are the Primacor^® Resins (Primacor 1430, Primacor 3414 and Primacor 5981, Dow Chemical Company, Midland, MI) which contain 10, 15, and 25 weight % acrylic acid residues in the copolymer, respectively. Another example of an ethylene-(meth)acrylic acid copolymer useful for practicing the invention is Nucrel^® 925 (DuPont, Wilmington, DE) which contains 15 %> by weight of (meth)acrylic acid residues.

Ionomer is another preferred alkaline soluble degradable material. Preferably, the ionomer is comprised of 10-30 % by weight (meth)acrylic acid residues, and, even more preferably, the ionomer is comprised of 15-25 % by weight (meth)acrylic acid residues. An ionomer product that is particularly suited for practicing the invention is Surlyn^® 8220 (DuPont, Wilmington, DE).

Still another prefeπed alkaline soluble degradable material is a blend of the above referenced ionomer and ethlyene-(meth)acrylic acid copolymer. In alternative embodiments, the ratio of ionomer to copolymer present in the blend is less than about 6:1, 4:1, 3:1, 2:1 or 1 :1. In still even other embodiments, the ratio of copolymer to ionomer is less than about 6:1, 4:1, 3:1, 2:1 or 1 :1.

In still other embodiments, especially those in which the container softens to release its contents, the degradable material comprises ethylene (meth)acrylic acid, ionomer, ethylene vinyl acetate, ethylene olefin copolymer, low density polyethylene, polycapryl lactone, poly(lactic acid), poly(glycolic acid), polypropylene, polystyrene, other polyolefins, copolymers thereof, or blends thereof. Types and grades of the foregoing materials can be selected, based upon known physical properties, to achieve the particular softening characteristics desired for particular applications. Such materials may be blended with degradable materials discussed above to enhance the softening properties of the polymer. Methods of preparing articles from such polymers, and the other degradable materials of this invention, are known generally in the art and, therefore, are not repeated herein.

In another embodiment, the degradable material comprises one or more fillers, which can alter the physical characteristics of the degradable container so formed. Particularly preferred fillers include materials known generally in the art, such as BaSO₄, CaSiO₃, CaCO₃, clay, glass fiber, or mixtures thereof. Other suitable fillers include talc, titanium dioxide, aluminum silicate (clay), kaolin, silica, magnesium carbonate, barium carbonate, calcium sulfate, diatomaceous earth, alumina, aluminum hydroxide, magnesium hydroxide, magnesium sulfate, magnesium oxide, zinc oxide, mica, zeolite, acid clay, calcium metasilicate, calcium oxide, ceramic, borosilicate glass and pulp/organic materials. For example, one of skill in the art would recognize that the use of fillers as set forth above can enhance the rigidity of articles made from the various degradable materials of this invention. The degradable material may, in separate embodiments, comprise greater than 5, 10, 20, 30, or 40 wt.% filler, and/or less than 40, 30, 20, 10, or 5 wt.% filler. Moreover, additional polymers may be added to the degradable material to provide for further desirable characteristics in the containers claimed herein. In a particularly suitable embodiment, polymers having a high modulus are added to improve the strength and rigidity of the material. Polyester, polypropylene, polym ethyl (meth)acrylic acid, high density polyethylene, polycarbonates, ABS or MBS ((meth)acrylonitrile butadiene styrene), polystyrene or nylon may be used to lower the cost of the article and to reduce the quantity of blend needed to obtain the desired properties. For instance, polyester may be used because, like polystyrene, it possesses a high modulus and thus can be used to both lower the cost of the degradable container as well as to increase the modulus of the article. Types and grades of the foregoing materials can be selected, based upon known physical properties, to achieve the particular characteristics desired for particular applications.

In addition to the materials set out above, the degradable material can also contain other ingredients, such as plasticizers, antifoaming agents and surfactants, lubricants, parting agents, stabilizers, pigments, dyes, brighteners, antioxidants, waxes, foaming agents, blowing agents, antistatic agents, antiblocking and other processing aids generally known in the polymer art. However, it is desirable that such additional ingredients not materially interfere with the degradability of the material used to form the degradable container or interfere with the discharge of the disposal liquid into which the degradable container is immersed. The amount and type of degradable material, as well as the presence or absence of any filler material or other additional ingredients, can be used to alter the physical characteristics of the resulting container. For example, when a container is formed from a blend of ethylene-(meth)acrylic acid copolymer, it has been found that increasing the proportion of ionomer to copolymer results in more rigid articles. Such compositions have been found to be suitable for forming suction containers with a rigid outer container which can satisfactorily serve as an intermediate source of suction. One of skill in the art would readily recognize the manner in which the ratios of ingredients may be varied to result in desired properties for the containers herein.

Blends of polymers may be formed by combining the polymers using any conventional technique that results in the formation of an intimate and uniform mixture of ingredients. Such suitable techniques include, for example, extrusion, compounding, and melt mixing.

Furthermore, one of skill in the art will recognize that the methods used to form the containers of the present invention will affect the materials chosen to construct the containers. For example, when a container is constructed with a blow molding technique using a composition comprising ionomer, the melt index of the ionomer utilized is preferably about 1 to 5. In contrast, when a container is formed from ionomer and constructed using an injection molding technique, the melt index of the ionomer is preferably about 10 to 20.

Figure 1 shows a degradable infectious waste container 100 for the collection of materials collected such as body fluids. Container 100 is degradable without causing significant risk to hospital personnel. Container 100 is, of course, just one embodiment of the broad class of containers included within this invention. Container 100 comprises a rigid vessel 102 made from the materials disclosed for receiving bodily fluids, such as those created during surgical procedures. The container has a con- nector/inlet portion 104 that also serves as a closure/lid that keeps the suction container sealed prior to disposal. After use, this container may be disposed of using the methods described herein.

The following examples illustrate two embodiments of the present invention. It will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed therein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

EXAMPLES

Blow Molded Container

Exact 4033 ' 50 parts Surlyn 8220² 50 parts

Injection Molded Container

Surlyn 8150³ 35 parts Primacor 5980⁴ 25 parts

'Ethylene copolymer manufactured by Exxon Chemical Company ²Ionomer manufactured by DuPont Chemical Company ³Ionomer manufactured by DuPont Chemical Company ⁴Primacor 5980 is manufactured by Dow Chemical.

Claims

What is claimed is:

1. A method of disposing of a sealed container and its contents comprising contacting the container with a disposal liquid at a temperature and for a time sufficient to lessen the structural integrity of the container, and to cause the container to release the contents.

2. The method of claim 1, wherein: a. the sealed container comprises a lid, and b. the lid loses its structural integrity when contacted with a disposal liquid at a sufficient temperature and for a sufficient time, and allows the contents of the container to be released through the opening.

3. The method of claim 1 wherein: a. the sealed container comprises a liner and a lid, and b. the liner loses its structural integrity when contacted with a disposal liquid at a sufficient temperature and for a sufficient time, and allows the contents of the container to be released.

4. The method of Claim 1, wherein the disposal liquid is a hot aqueous solution.

5. The method of Claim 1, wherein the disposal liquid is a hot aqueous solution and the container loses its structural integrity in the hot aqueous solution only at a temperature of at least 75 °C.

6. The method of Claim 1, wherein the disposal liquid is a hot aqueous solution and the container loses its structural integrity in the hot aqueous solution only at a temperature of at least 110°C.

7. The method of Claim 1, wherein the disposal liquid is alkaline.

8. The method of Claim 1, wherein the disposal liquid is alkaline, and the container loses its structural integrity in the disposal liquid only when the pH of the disposal liquid is above 8.0.

9. The method of Claim 1 , wherein the disposal liquid is alkaline, and the container loses its structural integrity in the disposal liquid only when the pH of the disposal liquid is above 10.0.

10. The method of Claim 1, wherein the container comprises polyvinyl alcohol.

11. The method of claim 1 wherein the container comprises polyvinyl alcohol, and the polyvinyl alcohol is highly crystallized, and has a degree of hydrolysis greater than 98%>.

12. The method of claim 1, wherein: a. the disposal liquid is alkaline, b. the container comprises an ethylene-(meth)acrylic acid copolymer comprising an acid content, and c. the acid content of the ethylene-(meth)acrylic acid copolymer is from 10 to 30 wt.%) of the ethylene-(meth) acrylic acid copolymer.

13. The method of claim 1 , wherein: a. the disposal liquid is alkaline, b. the container comprises a blend, c. the blend comprises an ethylene-(meth)acrylic acid copolymer having an acid content, and an Ionomer copolymer having a (meth)acrylic acid content, d. the acid content of the ethylene-(meth)acrylic acid copolymer is from 10 to 30 wt. % of the ethylene-(meth) acrylic acid copolymer weight, and e. the (meth)acrylic acid content of the Ionomer is from 10 to 30 wt. % of the Ionomer copolymer weight.

14. The method of claim 1 wherein the container comprises: a. polyvinyl alcohol, and b. polyvinyl, glycerol, glycerine, a filler, polyester, polypropylene, polymethyl (meth)acrylic acid, high density polyethylene, a polycarbonate, (meth)acrylonitrile butadiene styrene, polystyrene or nylon.

15. The method of claim 1 wherein the container comprises a lid or a liner, and the container, lid, or liner comprise: a. from 30 to 90 parts by weight of poly(vinyl alcohol), and b. from 70 to 10 parts by weight of a filler.

16. The method of claim 1 further comprising releasing the disposal liquid into a drain, sewer, or septic tank.

17. The method of claim 1 , wherein the disposal liquid is of a temperature sufficient to deactivate or kill any potentially infectious materials present in the suction container.

18. A degradable suction container comprising a polymer that softens sufficiently when immersed in a liquid below 100 °C to lessen the structural integrity of the container, and to cause the container to release its contents.

19. A degradable suction container comprised of a material that dissolves or disperses in a disposal liquid sufficiently to cause the container to release its contents.

20. The container of claim 19 wherein the material comprises poly(vinyl alcohol) or an ethylene-(meth)acrylic acid copolymer comprising an acid content, wherein the acid content of the ethylene-(meth)acrylic acid copolymer is from 10 to 30 wt.% of the ethylene-(meth) acrylic acid copolymer.