Note: Descriptions are shown in the official language in which they were submitted.
~ WO94125189 2i 6~68~ PCT~Sg4/04761
METHOD OF DISPOSAL OF
HOT WATER SOLUBLE GARMENTS AND LIKE FABRICS
TECHNICAL FIELD OF THE I~v~ ON
The present invention involves a method of disposing
S of garments after use. Specifically, the garments are composed
of non-woven, woven, knitted or otherwise formed film or
fabric of thermoplastic polymer or fiber which are water
soluble at temperatures only above approximately normal human
body temperature (37C).
BACKGROUND OF THE lN V ~ N~l~loN
Hospital patient care generates considerable
~uantities of infectious medical waste in primary and acute
care facilities. There has been a general conversion from
reusable, cleanable items, to disposable items over the last
three decades. These conversions were made to promote
antiseptic t~chniques in patient care and to decrease the
potential for cross-infections between patients, staff and the
general public. Recent federal and state government
regulations such as the Medical Waste Tracking Act of 1988 and
OSHA Medical Facility rules have resulted in a substantial
increase in medical waste that must be classified as
"infectious."
When a patient is admitted to a hospital, the patient
produces approximately 55 pounds of medical waste per day.
Approximately 20~ of this waste is infectious. The current
stated objective of the American Hospital Association and the
Centers for Disease Control is to treat medical waste as soon
as it is generated. Both organizations recognize that medical
waste is primarily an occupational hazard for health care
workers and not an environmental problem. The best way to
deal with infectious medical waste is to disinfect it at the
point of generation and dispose of the treated medical waste
with minimum handling and storage on premises.
The need for an effective way to dispose of medical
waste has been highlighted by the amendment made to 29 C.F.R.
1910.1030 which provides for the federal regulation under the
Occupational Safety And Health Act, 29 U.S.C. 655, 657 to
WO94/25189 21~ ~ ~ 8 2 PCT~S94/04761
control bloodborne pathogens. Specifically, the Act calls for
the establishment of an exposure control plan, the containment
of specimens of blood or other potentially infectious
materials and the general tightening of precautionary measures
to minimize the spread of disease. A safe and effective way
to dispose of hospital waste in the form of soiled garments
and apparel would greatly facilitate ~compliance with the
above-referenced Act. -
~
As a result, consumption of me~ical disposable woven
lo or non-woven products has been growing at a rate of
approximately~10% a year. In 1988, sales totaled approximately
1.155 Billion Dollars. It is projected that by 1992, sales of
medical disposable non-woven products will reach 1.54 Billion
Dollars.
Disposable medical fabrics are generally currently
composed of thermoplastic fibers such as polyethylene,
polypropylene, polyesters, polyamides and acrylics. These
fabrics can also include mixtures of thermoset fibers such as
polyamides, polyarimids and cellulosics. They are typically
10-100 grams per square yard in weight and can be woven,
knitted or otherwise formed by methods well known to those in
the textile arts while the non-wovens can be thermobonded,
hydroentangled, wet laid or needle punched and films can be
formed by blow or cast extrusion or by solution casting.
Although there is clearly a benefit in the use of
disposables in the medical arts by avoiding the necessity of
human contact with medical waste which is necessary in the
cleaning of comparable reusables, non-biodegradable
disposables are posing a problem which is only now being
recognized. Landfill sites are becoming increasingly burdened
with disposables which do not biodegrade for hundreds of
years, if ever. As landfill sites become fully exploited, new
sites must be found which are rightfully opposed by residents
located proximate to proposed site locations.
It is clear that others have produced useful articles
which at least break down or are caused to change their
physical confirmation when subjected to hot aqueous solutions.
For example, U.S. Patent No. 3,314,809 teaches the production
of transparent flexible films from hydroxypropyl cellulose
~ W094/25189 21 6 a6S2 PCT~S94/04761
which is taught to be "insoluble in water until the water
reaches a temperature of about 60 C." However, hydroxypropyl
cellulose, unlike polyvinyl alcohol, does not solubilize in
water but simply breaks down forming a cellulose derivative
t 5 residue.
The prior art has recognized uses for polyvinyl
alcohol compositions in the manufacture of water soluble
useful articles. For example, U.S. Patent No. 3,413,229
teaches the production of water soluble bags or pouches from
10 which packets or the like are produced containing such
materials as detergents, bleaches, insecticides, medicinals,
chemicals, dyes, pigments, industrial additives and other
materials. It is taught that the contents of the packets are
dispersed merely by dropping the packets into water whereupon
15 the bags dissolve and release their contents into aqueous
dispersions. However, the referenced patent teaches the
production of such films which are both hot and cold water
soluble.
Additional references, such as U.S. Patent No.
3,859,125 teach the production of layered articles which
include coatings of polyvinyl alcohol. The subject reference
teaches coating polyvinyl alcohol on a paper membrane whereby
it is taught that the coated paper is soluble in either high
or low temperature water. Again, it is incorrect to believe
that a cellulose sheet material would be "soluble" in an
aqueous solution. At best, cellulose merely disperses.
Similarly, U.S. Patent No. 4,343,133 teaches the coating of
polyvinyl alcohol onto a non-woven fiber sheet impregnated
with latices of polyvinyl acetate in the manufacture of a
premoistened towelette which can be disposed of by flushing
in plain water without danger of clogging a plumbing system.
There has been the teaching of various medical
related products which are generally in the form of articles
coated with polyvinyl alcohol employed to enhance disposal.
For example, European Patent Application No. 87310534.0
(Publication No. 0272816) teaches the production of an ostomy
pouch which can be disposed of in a toilet bowel. The pouch
is constructed from laminants of water swellable cold water
insoluble films and water-resistant tissue paper. Similarly,
WO94125189 i 216 0 6 ~ 2 PCT~S94/04761
U.K. Patent Application No. 2211088 teaches the production of
a liner for a bed pan or urine bottle made of polyvinyl
alcohol. It is taught that the liner may be disposed of by
treatment with water at a temperature above that which it
dissolves.
Both U.K. Patent No. 1,187,690 and Japanese Patent
No. 72041741 teach the production of stand alone polyvinyl
alcohol films which are water soluble. The U.K. patent teaches
the production of hospital bags~and packing material for such
products as detergents and agricultural chemicals while the
Japanese patent teaches the use of polyvinyl alcohol films to
make laundry bags which dissolve releasing soiled garments
contained therein. However, neither reference teaches the
unique films of the present invention which can be configured
into useful garments and like materials and which are soluble
in aqueous solutions only above a threshold value.
It is a desire in the creation of the present
invention to provide a method of disposing of garments,
linens, drapes, towels and other useful articles after use
while avoiding additional burdens being placed upon landfill
disposal sites.
It is yet a further desire to provide a method of
disposing of garments, linens, drapes, towels and other useful
articles after use such that the garment can be solubilized
and medical waste substantially sterilized in a single
operation.
These and further desires will be more readily
appreciated while considering the following disclosure and
appended claims.
SUMMARY OF THE INVENTION
The present invention involves a method of disposing
of garments after use which comprises providing the garments
as sheets or as woven, non-woven, knitted or otherwise formed
fabric of thermoplastic polymer or fiber. The polymer or
fabric garments are water soluble only at temperatures above
approximately the normal body temperature (37C). The
garments, linens, drapes, towels and other useful articles
composed of said polymer formulation are subjected to water
PCT~S94/04761
~ WO94/25189 2 1 6 ~ 6 8 2
at a sufficient temperature to substantially dissolve the
garments whereupon the water and dissolved polymer are
subjected to disposal.
DETAILED DESCRIPTION OF THE INVENTION
The present invention deals with the disposal of film
or fabric configured into such garments and articles as
drapes, towels, covers, overwraps, gowns, head coverings, face
masks, shoe coverings, CSR wraps, sponges, dressings, tapes,
underpads, diapers, wash cloths, sheets, pillow covers,
napkins and woven, non-woven, or otherwise formed fabric. Such
products are generally employed in the medical industry both
in hospitals, outpatient facilities and home environments.
Many of these products generally come into contact
with human bodily fluids and their disposal and disinfection
has become a matter of major concern in light of the lack of
biodegradability of prior products and the potential spread
of human fluid-born diseases such as hepatitis B and AIDS.
In order to cope with these difficulties, it is
proposed that polymer or fabric employed in the manufacture
of such items be composed of polymer films and/or fibers which
are soluble in hot aqueous baths, including water, either
alone or with the addition of surfactants, salts and bleaches
above 37C and preferably above 50C. Such fibers or sheets
would be insoluble in cold to warm baths below 37C, the
average temperature of the human body. Ideally, the polymer
or fabric would be soluble in baths only above 50C, and, most
preferably the polymer or fabric garments would be soluble
only in aqueous media between 80C to 90C.
Garments which are soluble in aqueous media below
37OC are useless as inadvertent secretion of bodily fluids
such as blood and urine would cause the polymer to solubilize.
Working with polymer which dissolves only at higher
temperatures such as above 50C or, ideally between 80C and
90C would prevent inadvertent solubilization yet remain ideal
in practicing the present invention. It is contemplated that
disposal in a hot water bath such as a washing machine at or
near the boiling point of water dedicated solely to
solubilizing garments, linens, drapes, towels and other useful
W094/25189 216 ~ 6 8 2 PCT~S94/04761
articles produced herein would also be an effective
disinfecting media. As such, two objectives would be
accomplished, namely, that the polymer or sheets would be
di~infected and would be solubilized for disposal through the
sewer system. Not only would this lessen the burden now being r
imposed upon current landfill sites but liguid sewer disposal
would prove a comparative low cost technique in ridding the -
user of such used garments.
Polymer or sheet mat~rials useful in practicing the
lo present method comprise p~1yvinyl alcohol with or without
acetyl groups, cross-linked or uncross-linked. The garments
are comprised of polyvinyl alcohol homopolymer that has been
highly crystallized by post drawing or heat annealing. Ideal
for use in the present invention would be a highly
crystallized, at least approximately 98% saponified polyvinyl
acetate. Commercially, polyvinyl alcohol sold under the
trademark Vinex 1003TM and 1002~ by Air Products could be
used herein. Useful fibers are typically 0.5 denier to 5.0
denier and are preferably from 1.0-2.0 denier and most
preferably sized at 1.2-1.5 denier. A commercially available
product for use in the present invention is either type T-B
(VEE 1290) or type T-5 (VPB 101) which are each available from
Kuralon as its PVA fiber. This material is sold in 44mm
lengths. The T-B product is sized at 1.2 denier while the T-5
product is sold in 38mm staple lengths of 1.5 denier.
The fabric useful in practicing the present
invention can be constructed by any well known technique for
making woven, non-woven, knitted or otherwise formed fabric.
Such non-woven tech~iques useful in practicing the present
invention include spun bonding, melt blowing or wet laying,
hydroentangling with cold water and/or thermally bonding with
30-70% of the surface melted to form, for example, a diamond
pattern. When products, such as diapers, are configured of
sheets of suitable thermoplastic material, the sheets are
approximately 1 to 6 mils in thickness and more preferably 1
to 3 mils in thickness and most preferably approximately 1.5
mils in thickness. Suitable non-woven fabric or sheets are
approximately from 15g/yd2 to 200g/yd2 in weight and more
preferably from 20g/yd2 to 70g/2 and most preferably from
~ W09412~189 7 216 0 6 8 2 PCT~S94/04761
25g/yd2 to 80g/yd2. Knitted or woven fabrics are approximately
50% heavier as needed for binding tapes, cuffs and related
appendages.
As noted in U.K. Patent No. l,187,690, it is
desirable to maintain a minimum level of moisture content of
polyvinyl alcohol pellets prior to melt extrusion. The
reference teaches that if moisture content of a film
composition exceedæ two percent by weight, steam evolves
during the melt extrusion leading to the formation of fine
holes or cavities in the film.
However, while the present invention also
contemplates drying to a level of approximately 0.5% (wt.)
water or less the polyvinyl alcohol pellets before extrusion
and, subsequent to the film formation, moisture is
lS reintroduced back into the film to prevent brittleness and
maintain usefulness. It is contemplated that the final PVA
film have between 1.5 to 15% (wt.), preferably 5 to 10% (wt.)
and most preferably approximately 7.5% (wt.) moisture content.
In order to further enhance the usability of sheet
material produced principally of polyvinyl alcohol, it is
contemplated that an anti-blocking agent be employed to reduce
hydrogen bonding between adjacent hydroxyl groups on separate
sheets. Suitable anti--blocking agents are members selected
from the group consisting of silicon dioxide (Sioz) polymer,
talc, calcium carbonate and fumed hydrophilic SiO2. Such
material should be employed between O.l to 5.0% (wt.) and most
preferably between 2 to 3% (wt.) based upon the weight of the
polyvinyl alcohol.
As noted previously, polymer or sheet material
useful in practicing the present invention is comprised of
polyvinyl alcohol with or without acetyl groups, cross-linked
or uncross-linked. It is proposed that the polyvinyl alcohol
be substantially fully hydrolyzed, that is, having 98% or
greater hydrolyzed acetyl groups.
For the sake of adequate mechanical strength,
polyvinyl alcohol-based sheet material should have a degree
of polymerization of at least 700 and no greater than
approximately 1500. Ideally, such materials should have a
degree of polymerization of approximately 900 and be
wo 94~2~189 2 ~ 6 0 ~ ~ 2 ~ PCT~S94/04761
substantially crystallized.
It is also noted that in producing polyvinyl alcohol
resins from the saponification of polyvinyl acetate,
impurities such as sodium acetate and sodium sulfate are found
in the resin. To provide a suitable film material, such
impurities must be kept below 1/2% (wt.) and preferably below
1/4% (wt.) of the polyvinyl alcohol resin. This can be
accomplished with a methanol water rinse or extraction.
To enhance the manufa~cture of suitable polyvinyl
alcohol resin-based film materials, suitable quantities of a
plasticizer are necessary. It is contemplated that up to 15~
(wt.) of a suitable plasticizer such as glycerine or
polyethylene glycol be employed to assist in providing a
smooth melt extrusion from the polyvinyl alcohol-based
pellets.
~ W094/25189 9 PCT~S94/04761
~"" 21~0~82~
As examples the following fabric samples were
manufactured on conventional thermal bonding equipment.
I.D. TL-0079.0 79.1 79.2 080.0 0080.1
Fibre Kuralon T-5 PVA (1.5 denier, 38 mm staple le~gth)
5 Pattern No. 2 2 2
Fabric Wt.
(gms/sq.yd) 27 44 47 35 43
~hickness (mil) 15 12 17 14 16
Tensiles-
10 (Grab-lbs)
Dry MD 8.3 11.7 16.6 13.8 16.1
Wet MD 3.2 4.8 4.6 3.1 6.0
~EY CD 2.0 2.3 4.3 3.8 5.2
Wet CD 1.0 1.5 1.7 1.3 2.3
Elongation(%)
~ry MD 11 10 12 12 11
pry CD 48 30 38 19 22
Mullen Burst
(p8i) Dry 11 15 19 13 16
Wet 10 14 19 13 15
I.D. TL-0079.0 79.1 79.2 080.0 0080.1
Hanle-0-Meter
(gms) 84 244 432 173 244
Trap Tear-MD1.7 2.1 3.5 2.7 2.9
CD 0.4 0.4 0.8 0.6 0.7
SUBSTlll~E SHEET (RULE 2~
1 0 PCT~S94/04761
W094/25189 ~ 21 ~ Q ~ ~ 2
It was found that the above-manufactured fabric
displayed nearly identical physical properties similar to
fabric manufactured from polyester and polypropylene. However,
the fabric manufactured above was unaffected by cool or warm
water (23-37C) but when exposed to hot water (80-90C),
immediately dissolved.
It is oftentimes desirable that the film be colored
with pigments or dyes such as azo or anthraquinone molecules.
U eful dyes include acids, basics, disperse, reactives and
vats. The pigments and dyes should be employed in an amount
between approximately 0.25 to 3.0% (wt.) based upon the weight
of the polymeric polyvinyl alcohol.
Surprisingly, it has been found that the
incorporation of a water repellent within the polyvinyl
alcohol film or fabric is quite a useful adjunct to minimize
surface attack by liquid moisture at a temperature lower than
that at which solubility occurs. It has been found that even
with polyvinyl alcohol films and fabrics which become water
soluble only at elevated temperatures, when exposed to water,
the surface of such material tends to take on a slick "feel"
and the use of water repellents tends to minimize this effect.
Suitable repellents include fluorocarbons offered by the
Minnesota Mining and Manufacturing Co. sold under its
trademarks FC 824 and 808. These materials are useful in the
range of between 0.1 to 2.0% (wt.) based upon the weight of
the polyvinyl alcohol polymer.
