|Publication number||US3209977 A|
|Publication date||Oct 5, 1965|
|Filing date||Apr 15, 1963|
|Priority date||Apr 15, 1963|
|Publication number||US 3209977 A, US 3209977A, US-A-3209977, US3209977 A, US3209977A|
|Inventors||Nathaniel A Lewis, Jr Thomas E Kirby|
|Original Assignee||Reynolds Metals Co|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (3), Referenced by (13), Classifications (12)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Oct. 5, 1965 N. A. LEWIS ETAL CONTAINER Filed April l5, 1963 INVENTOR. NATHANIEL A. LEWIS BY THOMAS E. K|RBY,JR.
United States Patent O 3,209,977 CONTAINER Nathaniel A. Lewis, Henrico County, and riliomas E.
Kirby, Ir., Chesterfield County, Va., assignors to Reynolds Metals Company, Richmond, Va., a corporation of Delaware Filed Apr. 15, 1963, Ser. No. 273,049 9 Claims. (Cl. 229-35) The invention relates to a novel improved water soluble container adapted to release its contents when immersed in water. More particularly, the invention concerns a water soluble plastic bag having at least one seam through which it is adapted to release its contents, said seam being interiorly resistant to the action ot wet contents of the bag.
Water soluble exible containers adapted to release their contents when immersed in water having a temperature up to about 100 F. and which are substantially soluble in hot water have been described in copending application of Gnittin Serial No. 219,833, tiled August 28, 1962, entitled Flexible Packaging System. Such containers are especially suitable for use as hospital laundry bags, diaper bags, and the like. lt is known that the soiled laundry for which these types of bags are used, including hospital bed linens, garments, towels, and similar articles, is contaminated with pathogenic organisms. Prevailing practice in hospitals and homes involves placing soiled laundry in cloth bags, which are porous and permit the escape of bacteria through the bag Walls. During the handling of cloth bags via laundry chutes and other means of transportation, pathogenic bacteria are disseminated by currents of moving air, finding their way into clean linen supplies, food utensils, personnel uniforms, buildings and equipment, and creating serious problems of infection spread and control. Proposals to reduce these hazards by employing bags made of impervious and insoluble bags made of plastic films such as polyethylene, have been ineffective because bacteria are spread when the contents are dumped out into the washing machines, and because the disposal of the bags by incineration itself presents problems.
One form of water soluble flexible container which has been proposed comprises oppo-sing panels of hot water soluble flexible plastic material, with a layer of cold water sensitive plastic material interposed between said panels in position to be contacted by water when the container lis immersed in the water, the panels and the interposed plastic layer being bonded .to form a seam portion of the container, and the plastic layer being readily softened by water at a temperature up to about 100 F. to eiiect release of the seam. Thus, for example, two sheets of hot water soluble flexible plastic materials may be superimposed .to define a hollow body portion of the container when the container is distended, with a tape of cold water sensitive plastic interposed between the sheets adjacent a longitudinal edge, the sheets and the interposed tape being bonded to form a seam. The top margins of the sheets are left separable to provide an opening for filling the container, while the sheets are bonded directly at their remaining edge margins, as by heat sealing.
A bag of the type described is well suited for holding dry soiled linens, as well as damp or wet linens. The latter may be at body .temperature or colder. Hospital laundry practice employs initial rinsing steps which are carried out with water at body temperature or colder in order to loo-sen and flush away stains from blood and body discharges. This is followed by a hot water wash involving sudsing cycles with detergents and bleaches at temperatures customarily above about 145 F., and Water lCe rinses. The Water soluble laundry bag is dissolved completely by the hot Water and passes into the waste disposal system.
During periods of heavy flow of soiled articles, which may be damp or wet, circumstances may necessitate the storage of soluble bags of the type described containing wet linens for extended times until the laundering facilities and equipment become available. Under these conditions it is desirable to provide a container structure whereby the cold-water releasable portions of the bag seam or seams are protected from contact with any moisture emanating from the contents during peri-ods of storage, so that the contents may not be prematurely released.
In accordance with the invention, a water soluble laundry bag is provided which will hold wet linens indeiinitely at body temperature or colder, and permit these linens to be contacted almost immediately by the cold Water flush when the bag and its contents are placed in a washing machine, by release through at least one cold-water separable seam thereof, said seam being interiorly resistant to the action of wet contents of the bag. The release seam is protected against the action of moisture emanating from the wet contents so that premature release of the contents, such as upon prolonged storage of the bag and contents, does not occur. When the bag and contents are exposed to a cold water flush in the washing machine, .the contents are exposed through the released seam or seams to the action of blood and stain removing cold water ushes in the machine; subsequently when hot water containing detergents, soaps, bleaches and the like is added, the laundry bag will dissolve entirely and be disposed `of in the Waste waters from the machine.
These and other objects, advantages and details Will become apparent as the description proceeds, and from the accompanying drawings, in which FIGURE 1 is a perspective view of one embodiment of a laundry bag constructed in accordance with the invention;
FIGURE 2 is a section taken on the line 7-7 of FIG- URE l, showing a detail of the side seam;
FIGURE 3 is a perspective view of another embodiment of the invention;
FIGURE 4 is a section taken on the line S- of FIG- URE 3, showing a detail of the side seam;
The container 1 is formed from a pair of superimposed hot Water soluble plastic sheets 2 of generally rectangular configuration. In the embodiment illustrated in FIG- URE l, the bag is provided with at least one releasable seam 3. The seam structure corresponding to the ernbodirnent of FIGURE l is shown in more detail in FIG- URE 2, which illustrates the overlapping junction of panels 2 and an externally disposed cold water sensitive plastic layer or tape 4. The bag contains at least one releasable seam of the type shown in FIGURE 2, although both longitudinal edges may be so constructed. The panels or sheets 2 are bonded along their lower edges to form a bottom seam 5, as, for example by heat sealing. The upper margins 6 of the panels are separable to provide an opening for lling the container. The embodiment depicted in FIGURE 3 has similar configuration, but the seam structure is different and is shown in more detail in FIGURE 4. While the bags shown in FIGURES l and 3 are depicted as rectangular in shape, it will be understood n that they may be made in any desired shape. It Will be understood further that a generally tubular body may be provided with at least one seam of the types shown in FIG- URES 2 and 4, and that such seam may be transverse as well as longitudinal, and that the seam need not extend completely to the bottom edge of the bag.
In the embodiment shown in FIGURES 1 and 2, the bag is formed by bending or reversely folding a single continuous panel 7 of hot water soluble plastic film so that the folded longitudinal edge 8 thereof will enclose the longitudinal edge portion 9 of the opposing panel 10 of the bag. A strip or tape 4 of cold Water sensitive plastic material is applied so as to overlie the longitudinal edge of panel 7 and the adjacent portion of panel 10 thus forming a seam, the tape 4 adhering to and bridging the exterior of folded edge 8 and the portion of panel 10 adjacent the enclosed edge 9 thereof, The externally disposed tape portion 4 is thus protected from contact with moisture or water which may be present inside the bag, by virtue of the lap joint between the reversely folded edge 8 of sheet 7 and the edge 9 of sheet 10 received therein. If it is desired to further protect the tape portion 4 against any possible seepage of moisture from the interior of the bag, the overlapping fold S and the panel edge 9 may have therebetween a thin layer of a suitable sealing compound 11, such as, for example, petroleum jelly. The enclosed longitudinal edge portion 9 of panel 10 is substantially planar.
In the embodiment of FIGURES 3 and 4, the bag is formed by bending or reversely folding both panels 12 and 14 of the bag so that the folded longitudinal edge 13 of panel 12 will lap and enclose the oppositely directed folded longitudinal edge 1S of panel 14, as shown in FIG- URE 4. This construction provides a particularly moisture and water-tight seam. Here also a strip or tape 16 of cold water sensitive plastic material is applied so as to overlie the longitudinal edge of the panel 12 and the adjacent portion of panel 14, forming a seam therewith, the tape 16 overlapping the panel edge 13 and adhering to said edge and to the body portion of panel 14 adjacent to the enclosed edge 15. The tape 16 is thus also fully protected against access thereto of moisture or water inside the bag by virtue of the double reverse lapped folds at 13 and 1S. If desired a sealing compound as at 11 FIG. 2 may be applied, as mentioned previously, between edge 13 and panel 14, or between edge and panel 12, or both.
In the embodiments shown in FIGURES l and 3, the bags are provided with two cold-water releasable longitudinal seams, but it will be understood that where only a single releasable seam is desired, the bags may each be formed by bending a single panel of hot water soluble film back upon itself and then joining the free edges along one margin in seams of the type shown in either FIGURE 2 or 4, While the bottom bag margin is heat sealed at S.
The manufacture of the containers of the invention may be carried out in several ways. Thus, to make the embodiment shown in FIGURE 1, a sheet of hot water soluble plastic film 7, of sufficient width to provide two reversely folded edges 8 is positioned beneath a somewhat narrower sheet 10 and fed into a suitable apparatus of conventional type whereby the longitudinal edges 8 of sheet 7 are folded over to enclose the longitudinal edges 9 of sheet 10. A sealing compound 11 may be applied to edge portion 9 at the same time, if desired. The portions 8 and 9 are lightly pressed together at relatively low temperatures between about 200 and about 300 F., preferably about 25 0 F., and the cold-water soluble tape 4 is applied simultaneously by being moistened on its under surface very slightly. The temperature and pressure of adhesion are just suliicient to bond the body portions and the overlying tape, but insufficient to create a heat seal, or to bond the body panel portions together. In accordance with another method of manufacture, a mandrel is inserted between the panel portions to keep them separated and to avoid sealing the body portions together; a heat seal is applied to bond the tape portion to the exterior edges.
It will be understood that in either embodiment, the bottoms of the bags may be heat sealed in accordance with conventional practice, or they may be sealed with a suitable adhesive.
The containers of the invention, particularly laundry bags, have been tested in hospital applications and have been found to possess numerous advantages not previously obtainable using known types of containers. Among these advantages are a significant reduction in the incidence of airborne bacteria and other organisms. The filled bags can be dropped through multistoried laundry chutes without damage or loss of contents. The invention permits the use of a single type of bag for dry, damp, wet or soiled hospital linens, and reduces labor costs in the laundry by eliminating the unpacking steps previously required, and by speeding loading time of the washing machines. At the same time the new bags do not interfere with the use of the cold flush in the washing machines to eliminate setting of blood stains and the like, in accordance with standard hospital procedure.
The laundry bags lof the invention may readily be filled by suspending them from a ring stand or even over the back of a chair. Wet or dry hospital linens may be in serted up to the normal capacity of the bag. The bag is then closed by gathering the throat and tying it with a cold water soluble plastic tape. The bag is transported to the laundry room on a cart or via a laundry chute. In the laundry r-oom the filled bag is thrown directly into the washing machine without being opened or loosened. In the wash wheel of the machine, the first flush of water at body temperature or colder is introduced to avoid the setting of stains from blood and other body discharges. This iirst hush acts upon the cold water soluble tape at the throat of the bag and upon the seam tapes or layers 4 of cold water sensitive plastic. The weakened tape and side seams rupture under the impact of the wash load and the front and rear panels fall apart, allowing the soiled linen contents to spill out into the water. After several cold rinses, the hot water sudsing and rinsing cycles are performed, during which the entire laundry bag dissolves, including both the hot water soluble panel sheets and the cold water soluble tapes, and is removed in the discharge from the washing machine.
The water sensitive flexible plastic material employed for the fabrication of containers in accordance with the presently preferred practice of the invention is polyvinyl alcohol sheet or film, of varying thickness, and of varying types, depending upon the water sensitivity or solubility characteristics desired.
For the container panels, there are two film characteristics of importance: (a) hot water solubility, and (b) damp stability. The criterion of hot water solubility which has proven desirable is that the panel must dissolve completely in 170 F. water within a period of 5 minutes, with agitation. At the same time, the panel material must be substantially insoluble in supply water. Accordingly, the expression hot water soluble is used herein to designate materials which are soluble in water at higher temperature but are substantially insoluble in water at about F. or lower. Damp stability is deiined as the ability of the film to maintain its integrity as a iilm while in contact with damp linens.
It has been found advantageous to prepare the hot water soluble panel material from polyvinyl alcohol formulations which have a relatively low glycerol content in order to reduce sensitivity to moisture. Generally, between about 10 and about 18 pounds of glycerol, and preferably between about 13 and about 16 pounds of glycerol, per 100 pounds of resin, are dcsirably included in the formulation. Thus, there may be employed for the bag panel material, polyvinyl alcohol film material having the general range of hot water solubility desired, but with their damp stability controlled by the glycerol coutent.
The polyvinyl alcohol film to be used for the hot water soluble panels preferably has the following characteristics:
Thickness 0.5- mils. Average yield 21,600 sq. in./lb./mil. Specific gravity lll-1.31. Tensile strength 6,000 p.s.i. (minimum). 100% modulus (force required to double the length) 2,500 p.s.i. (minimum). Elongation SOO-600%. Internal tear resistance 500 gm./mil (minimum). Heat sealing 260 F., 510 sec. Flammability Slow burning.
The cold water sensitive polyvinyl alcohol which is used for tying tape and for side seam sealing at 4 in accordance with the invention is one which tends to soften in cold water, although not necessarily to dissolve completely. By cold water is meant water at a temperature up to about 100 F. Thus, for practical purposes a suitable cold water sensitive tape or layer is one which will release the contents of the bag in cold Water in less than 2 minutes, preferably less than l minute. A suitable commercially available cold-water sensitive tape is Reynolon PVA/WS-13.
Cold water sensitive polyvinyl alcohol film or use as a seam material and for binding the bag mouth preferably has the following characteristics:
Thickness About 0.015 in. Average yield 21,600 sq. in./lb./ml. Specific gravity 1.21-1.31. Tensile strength 2,000 p.s.i. (minimum). 100% modulus (force required to double the length) 1,000 p.s.i. (minimum). Elongation Z50-600%. Internal tear resistance 200 gm./ml (minimum). Heat sealing 300 F., l sec. Flammablity Slow burning.
Extensive evaluation of these laundry bags in actual hospital use has demonstrated their suitability in general, pediatrics and nursery wards.
While present preferred embodiments of the invention have been illustrated and described, the invention may be otherwise variously embodied and practiced within the scope of the following claims.
What is claimed is:
1. A water soluble plastic lm laundry bag for holding wet linens at body temperature or colder and which releases its contents when immersed in water having a temperature below about 100 F. and thereafter dissolves completely in hot water, comprising superimposed panels of hot water soluble flexible plastic film having good damp stability, the top margins of the panels being separable to provide. an opening for filling the bag, said panels having at least one releasable side seam portion along one pair of marginal edges thereof comprising a longitudinal edge of one panel reversely folded to enclose a longitudinal edge of the opposing panel and a layer of cold water sensitive plastic material positioned adjacent to said longitudinal edges and overlapping and adhering to the exterior of said folded edge and the body portion of said opposing panel, said plastic layer being readily softened by water at a temperature below about 100 F. to effect release of the seam, said panels being bonded together directly to form seams at their remaining edge margins.
2. The laundry bag of claim 1 in which the hot water soluble plastic film is polyvinyl alcohol.
S. The laundry bag of claim 1 in which the cold water sensitive plastic material is cold water soluble polyvinyl alcohol.
4. A container for effecting self-release of contents therewithin when immersed in water comprising a pair of superimposed panels of flexible material, said panels being connected along a plurality of edge margins t-o define a contents-receiving pocket, one of said connected edge margins including a water releasable seam protected from inadvertent release by moisture internally of said container present in said contents, said releasable seam comprising a reversely-folded longitudinal marginal edge of one of said panels receiving within the fold thereof the adjacent marginal edge of the other of said panels to prevent moisture leakage therepast from interiorly of said container,
and a strip of water-sensitive plastic material disposed exteriorly of said container in bridging overlying bonded relation to the reversely folded marginal edge of said one panel and the adjacent portion of said other panel to secure'said panels together therealong,
said plastic strip having the characteristic of being readily softened by water for easy rupture to effect release of the seam and discharge of the container contents therethrough. 5. A container for effecting self-release of contents therewithin when immersed in relatively cold Water comprising a pair of superimposed panels of flexible plastic material soluble in hot water in excess of about F., said panels being connected along a plurality of edge margins to define a contents-receiving pocket,
one of said connected edge margins including a coldwater-releasable seam protected from inadvertent release by moisture interiorly of said container present in said contents, said releasable seam comprising a reversely-folded longitudinal marginal edge of one of said panels receiving within the fold thereof the adjacent marginal edge of the other of said panels to prevent moisture leakage therepast from interiorly of said container,
and a strip of cold-water-sensitive plastic material disposed exteriorly of said container in bridging overlying bonded relation to the reversely folded marginal edge of said one panel and the adjacent portion of said other panel to secure said panels together therealong,
said plastic strip having the characteristic of being readily softened by water for easy rupture at a temperature below about 100 F. to effect release of the seam and discharge of the container contents therethrough.
6. The container of claim 5 in which the enclosed longitudinal edge portion -of said other panel is substantially planar.
7. The container of claim 5 wherein said connected edge margins of said panels include a plurality of said cold-water releasable seams.
8. The container of claim 5 wherein said other panel marginal edge is reversely folded in a direction opposite to that of said one panel to further insure against moisture leakage therepast to the exterior of the container.
9. The container of claim 5 wherein a sealing compound is provided between the lapping surfaces of said panel edge margins at said releasable seam.
References Cited by the Examiner UNITED STATES PATENTS 2,331,955 10/43 Beebe et al 229-62 2,750,027 6/ 56 Cummings 206-65 FOREIGN PATENTS 1,192,726 4/59 France.
THERON E. CONDON, Primary Examiner.
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|U.S. Classification||383/1, 220/DIG.300, 428/913, 383/107, 229/5.6, 428/192, 229/5.7|
|Cooperative Classification||D06F95/006, Y10S428/913, Y10S220/30|