Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS TO PRODUCE HYGIENICALLY CLEAN TEXTILE
BACKGROUND OF THE INVENTION
[0001] Hygienic cleanliness of textiles has become an increasingly
important aspect of the
laundering process. Presently, much of the United States and European Union
rely on thermal
disinfection as the means to verify that textiles have been properly washed
and are hygienically clean.
In the US, the CDC guidelines state that one way to help achieve hygienic
disinfection for hot-water
washing is to wash at 160 F for a minimum of 25 minutes. The CDC also states
that several studies have
demonstrated that lower water temperatures of 71 F-77 F can reduce microbial
contamination when
the cycling of the washer, wash chemistry are controlled.
[0002] Due to production demands, textiles processed through continuous
batch washers (CBW's)
do not typically meet the CDC thermal disinfection requirements of 160 F for
25 minutes. In addition,
although washing machines are programmed to reach 160 F, many lack a mechanism
to verify that
160 F is reached and maintained.
[0003] Thermal disinfection has been shown to be insufficient in killing
spore forming bacteria, such
as C. diff. C. diff. can survive extended heating at 160 F. Temperatures of
145-160 F may actually
enhance spore germination of some aged spores.
[0004] EPA registered sanitizers/disinfectants are sometimes used in
healthcare laundries. When
used properly, these sanitizers/disinfectants have kill claims on certain
organisms. The deficiency in
using these sanitizers/disinfectants is that they do not have kill claims on
many organisms present in the
healthcare environment. One such sanitizer/disinfectant has kill claims for
Staphylococcus aureus,
Klebsiella pneumonia, Pseudomonas aeruginosa, methicillin resistant
Staphylococcus aureus (M RSA),
Acinetobacter baumannii, Listeria monocytogenes, Ecsherichia coli, and
Salmonella enterica. This
sanitizer/disinfectant does not address other significant problematic
organisms, such as C. diff, Giardia,
Legionella, fungi, and molds.
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[0005] In commercial laundries, textiles are typically laundered at
elevated temperatures, such as
150 F under alkaline conditions. There are certain detergents on the market
which permit the textiles
to be laundered at lower temperatures.
[0006] Certain textiles require a bleaching step. This is particularly
required for white textiles such
as white linen. Chlorine-based bleaches, such as sodium hypochlorite, are
typically used. Generally the
commercial laundries bleach such textiles at temperatures about 150 F, similar
to the laundering
temperature, and at relatively high pHs, around 10.2 to 10.8. If the chlorine
bleaches are used at lower
pHs, the textiles are damaged by the bleach.
[0007] Also, once a textile is laundered at a high temperature, it must be
brought down to room
temperature gradually or wrinkles will set in. Generally, the temperature of
the textiles is lowered by
going through a series of rinsing steps wherein in each step the temperature
of the rinse water is slightly
lower than the previous temperature. This allows the temperature of the
textile to be lowered to room
temperature without setting in wrinkles.
[0008] This operation is relatively expensive, requiring a significant
amount of energy to raise the
temperature of the textiles to the effective laundering temperature. It also
requires a great deal of time
for step down rinsing.
SUMMARY OF THE INVENTION
[0009] The present invention is premised on the realization that one can
effectively launder and
bleach textiles by initially washing the textile at a low temperature,
generally 140 F or lower, and
subsequently bleaching the textiles, again at a low temperature of less than
140 F, at a pH less than 9.5,
generally from about 7 to 9. This effectively launders and bleaches the
textile without causing any
damage to the textile, which typically would be expected when bleaching at
such a low pH.
[0010] In one embodiment of the present invention, particularly suitable
for laundering hospital
linens, the linens are cleaned in a four zone process, the first zone designed
to remove chlorhexidine
also referred to as Hibiclens, wherein a concentrated high-performance
detergent is used, along with a
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Hibiclens remover, such as Hibiclear, to remove any chlorhexidine from the
fabric, preventing it from
setting in subsequent zones. In the second zone, the linens are washed, again
at a low temperature,
generally 140 F or less, such as 100 F, down to 85 F. In this zone, a high
performance laundry
detergent, along with a concentrated alkali, is added. This zone helps to
reduce microorganism
contamination. In the third zone, the textiles become hygienically clean by
treating the textiles with
sodium hypochlorite, a bleach activator, at a pH of less than 9.5, generally 7
to 9, more particularly 7-8,
again at a temperature less than 140 F, generally 100 F or less. Finally, in
the fourth zone, the linens are
rinsed and the pH adjusted to about 7. At this stage, softeners can be added
if required.
[0011] The objects and advantages of present invention will be further
appreciated in light of the
following detailed description and brief description of the Figures, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a graph showing tensile strength of a cotton fabric after
repeated washes; and
[0013] FIG. 2 is a graph showing tensile strength of a 65/35
polyester/cotton blend after repeated
washes.
DETAILED DESCRIPTION OF THE INVENTION
[0014] According to the present invention, textiles are laundered in a
manner that ensures
destruction of bacteria and other pathogens to provide hygienically clean
textiles. The washing process
will be conducted in typical commercial laundry facilities. Generally, any
commercial laundry equipment
can be used in the process of the present invention. One such typical
apparatus is a tunnel washing
apparatus, generally one having at least four zones.
[0015] The textiles are initially subjected to a low temperature, low pH
laundering. In this first
zone, the textiles are treated in a manner, well-known to remove
chlorhexidine, an antimicrobial agent
typically used in hospitals, also referred us to as Hibiclens. In this
process, the textiles are subjected to a
wash at an acid pH to prevent the chlorhexidine from setting. The wash washing
solution can include
Hibiclear, a commercially available product which is designed to facilitate
removal of chlorhexidine.
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[0016] This initial zone washing is conducted generally at a lower
temperature, preferably at 140 F
or less, such as 130, 120, 110 and generally about 100 F. The initial wash is
conducted for a time
effective to remove any chlorhexidine present and generally from about 2 to
about 8 minutes and
generally about 8 minutes. This step is unnecessary for textiles that do not
include chlorhexidine.
[0017] Once the textiles are treated in the initial zone, they pass to a
wash zone, where they are
washed using a high-performance, low temperature laundry detergent, generally
a nonionic surfactant-
based detergent at an alkaline pH. This washing step is conducted at a
temperature of 140 to 85 F,
generally 130 F to 95 F, 120 F or less, 110 F or less and preferably at about
100 F. The time during
which the textiles are treated in the wash zone may vary, depending upon the
materials being
laundered. In most applications, the time is from 6 to about 15 and generally
about 12.
[0018] After the laundry passes through the wash zone, the washing liquid
is separated from the
textiles. The textiles are then passed to a third zone, which is a pathogen
removal zone or a bleaching
zone. In this zone, the textiles are treated with a bleach solution, typically
sodium hypochlorite at a pH
of 6.5 to 9.5, generally 8 to 6.5 and, in particular, a pH of 7. The pH is
adjusted as needed by the
addition of an appropriate water soluble buffer, such as urea sulfate.
[0019] The concentration of the bleach will be about 5 ounces to 30 ounces
per hundred weight
textile or 25 to 500 ppm. In addition to the sodium hypochlorite, a bleach
activator is added, such as
Pathfree. This will effectively established the pH within the desired range.
The temperature in this zone
will be maintained at 140 F or less, generally 130 F or less, 120 F or less, 1
10 F or less and typically at
about 100 F. In addition to sodium hypochlorite, other suitable bleaches
include powdered bleaches
such as lithium hypochlorite, trichloroisocyanuric acid and hypochlorous acid.
[0020] The washing solution in zone three should have a minimum oxygen
reduction potential of
665MV, which is achieved by establishing sufficient sodium hypochlorite and an
effective pH. The
clothing is subjected to the hypochlorite solution for about 4 to about 30
minutes, which is more than
adequate to destroy potential pathogens on the textile.
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[0021] Once the textile has passed through the third zone, it is rinsed in
a fourth zone or a finishing
zone. In this zone, which is optional, any remaining wash chemicals are
removed from the textiles and
the pH is adjusted to a proper finish pH of 6-7. Softener may be added as
required by the end-user.
[0022] The present invention has many different advantages. In particular,
all the zones are
operated at lower temperatures, generally around 100 F. This eliminates the
need for either adding or
removing energy from the textiles during the laundry procedure. In addition to
effectively cleaning the
textiles, they are disinfected, destroying pathogens utilizing the third zone
which effectively kills the
pathogens with the hypochlorite at a relatively low pH and low temperature.
Again, the low
temperature reduces costs because the temperature of the textile does not have
to be adjusted in going
from the wash zone to the pathogen destruction zone.
[0023] Finally, the present invention reduces the damage to the textiles,
as compared to current
bleach parameters which operate at a higher temperature and higher pHs. As
shown in FIG. 1, the
tensile strength of cotton is measured after repeated washes, either under
current bleach parameters or
the low temperature bleach parameters as discussed above for zone three.
Particularly after 10 or 25
launderings or washes, the tensile strengths of the textiles bleached with the
bleach parameters of the
present invention are substantially higher than those bleached using current
bleach parameters (i.e.
higher temperatures and pHs). Likewise with the 65/35 polyester cotton blend,
similar improved results
are achieved, as shown in FIG. 2.
[0024] In Examples 1 and 2 below, the effectiveness of these wash
parameters reduce known
amounts of microorganisms was studied.
[0025] EXAMPLE 1:
Objective:
The objective was to evaluate the effectiveness of the present invention as a
means of
reducing known amounts of microorganisms.
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Test Parameters:
The effect of the present invention on known quantities of microbes was tested
to examine
how the different wash parameters affect the different organisms. One by one
inch square
swatches of linen were inoculated. After inoculation the swatches were allowed
to dry for
thirty minutes in a sterile petri dish. Upon completion of the dry time, the
swatches were
pinned to a mesh net and subjected to the differing wash parameters.
Preparation of inoculum:
Each organism was grown in trypitic soy broth for approximately 24 hours at
32.5 C in a
sterile baffled flask, while shaking on a Thermo Scientific multipurpose
orbital shaker. After
the incubation period the suspension was diluted with tryptic soy broth, to
yield a specific
absorbance with the Hach DR 2700 spectrophotometer. The adjusted suspension
contains
approximately 5.0 x 108 CFU/mL.
Sample identification ¨ Hospital/Hotel linen 70% cotton 30% polyester 1.0 x
1.0 square
swatches.
Test organisms ¨
= Escherichia coli - ATCC # 8739
= Pseudomonas aeruginosa ¨ ATCC # 9027
= Staphylococcus aureus ¨ ATCC # 6538
= Klebsialla pneumoniae ¨ ATCC # BAA-1144
= Salmonella enterica subspecies typhimurium ¨ ATCC # 13311
Method ¨ Membrane filtration (sterile eluation 45 mL), total aerobic plate
count
Wash and chemistry tested:
Classification: Sheets
Load weight: 100% capacity
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Process 2oz/cwt Bleach-8 minute
contact time
Usage/35
Operation Time Temperature Level Chemical lb
*Bleach-Sub 8/1 100 Low Bleach 22 mL
85% urea 4m1
sulfate
Rinse 2/1 split High
Rinse 2/1 cold High
*Sour-Soft 4/1 cold Low Pinn. A/C 9 mL
Pinn. Sour 0 mL
Total Time: 22 Minutes
Inoculu
CFU/m Calculated
Inoculum m
L CFU/Swatch LoglO/Swatch
Volume
3.0x10
E. coli 40 pi 1.9x108 8.28
9
2.0x10
P. aeruginosa 40 pi 8.1x106 6.91
8
2.0x10
40 pi
8
S. aureus 8.0x106 6.90
2.0x10
40 pi
9
K. pneumoniae 8.2x107 7.90
3.1x10
40 pi
9
S. typhimurium 1.29x108 8.1
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Results:
Log Reduction
Logio
Treatments (3 replicates each) CFU/Swatch (calculated
Survivors
CFU/Swatch)
E.coli 1-1 <10 <1.0 7.28
E.coli 1-2 <10 <1.0 7.28
E.coli 1-3 <10 <1.0 7.28
P.aeruginosa 1-1 <10 <1.0 5.91
P.aeruginosa 1-2 <10 <1.0 5.91
P.aeruginosa 1-3 <10 <1.0 5.91
S aureus 1-1 <10 <LO 5.90
S aureus 1-2 <10 <1.0 5.90
S aureus 1-3 <10 <LO 5.90
K. pneumoniae 1-1 <10 <1.0 6.90
K. pneumoniae 1-2 <10 <1.0 6.90
K. pneumoniae 1-3 <10 <1.0 6.90
S. typhimurium 1-1 <10 <L0 7.1
S. typhimurium 1-2 <10 <1.0 7.1
S. typhimurium 1-3 <10 <1.0 7.1
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[0026] EXAMPLE 2:
Objective:
The objective was to evaluate the effectiveness of resource conservation wash
parameters as a means
of reducing known amounts of microorganisms.
Test Parameters:
The effect of eight separate laundry processes on known quantities of microbes
was tested to examine
how the different wash parameters affect the different organisms. One by one
inch square swatches of
linen were inoculated. After inoculation the swatches were allowed to dry for
thirty minutes in a sterile
petri dish. Upon completion of the dry time, the swatches were pinned to a
mesh net and subjected to
the differing wash parameters.
Preparation of inoculum:
Each organism was grown in trypitic soy broth for approximately 24 hours at
32.5 C in a sterile baffled
flask, while shaking on a Thermo Scientific multipurpose orbital shaker. After
the incubation period the
suspension was diluted with tryptic soy broth, to yield a specific absorbance
with the Hach DR 2700
spectrophotometer. The adjusted suspension contains approximately 5.0 x 108
CFU/mL.
Sample identification ¨ Hospital/Hotel linen 70% cotton 30% polyester 1.0 x
1.0 square swatches
Test organisms ¨
= Escherichia coli - ATCC # 8739
= Pseudomonas aeruginosa ¨ ATCC # 9027
= Staphylococcus aureus ¨ ATCC # 6538
= Klebsialla pneumoniae ¨ ATCC # BAA-1144
= Salmonella enterica subspecies typhimurium ¨ ATCC # 13311
Method ¨ Membrane filtration (sterile eluation 45 mL), total aerobic plate
count
Wash and chemistry tested:
Formula:
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2 oz/cwt Bleach and 100 F
Classification: Casino/Hotel sheet
Load weight: 100% capacity
RC Formula 2oz/cwt Bleach-8 minute
contact time
Operation Time Temperature Level Chemical Usage/Cwt
*Bleach-Sub 10/1 100 Low spectrum 0 mL
Express 0 mL
Bleach pH6 22 mL
Rinse 2/1 split High
Rinse 2/1 cold High
*Sour-Soft 4/1 cold Low Pinn. A/C 9 mL
Pinn. Sour 0 mL
Total Time: 22 Minutes
Inoculum Calculated
Inoculum CFU/mL
Volume CFU/Swatch
LoglO/Swatch
E. coli 3.0x109 40 u.1_ 1.9x108 8.28
P. aeruginosa 2.0x108 40 u.1_ 8.1x106 6.91
S. aureus 2.0x108 40 u.1_ 8.0x106 6.90
K. pneumoniae 2.0x108 40 u.1_ 8.2x107 7.90
S. typhimurium 3.1x108 40 u.1_ 1.29x108 8.1
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Results:
Log Reduction
Logio
Treatments (3 replicates each) CFU/Swatch (calculated
Survivors
CFU/Swatch)
E.coli 1-1 <10 <1,0 7,28
E.coli 1-2 <10 <1,0 7.28
E.coli 1-3 <10 <1,0 7.28
P.aeruginosa 1-1 <10 <1,0 5.91
P.aeruginosa 1-2 <10 <1.0 5.91
P.aeruginosa 1-3 <10 <L0 5.91
S aureus 1-1 <10 <1.0 5.90
S aureus 1-2 <10 <1,0 5.90
S aureus 1-3 <10 <1,0 5,90
K. pneumoniae 1-1 <10 <1.0 6.90
K. pneumoniae 1-2 <10 <1.0 6.90
K. pneumoniae 1-3 <10 <1.0 6.90
S. typhimurium 1-1 <10 <1,0 7.1
S. typhimurium 1-2 <10 <1,0 7.1
S. typhimurium 1-3 <10 <1.0 7.1
_
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RC Formula 4 minute contact time
Operation Time Temperature Level Chemical
Usage/Cwt
*Bleach-Sub 10/1 100 Low
Bleach pH6 22 mL
Rinse 2/1 split High
Rinse 2/1 cold High
*Sour-Soft 4/1 cold Low Pinn. A/C 9 mL
Pinn. Sour 0 mL
Total Time: 22 Minutes
Inoculu
Calculated
Inoculum CFU/mL m
CFU/Swatch LoglO/Swatch
Volume
E. coli 2.4x109 40 u.1_ 9.6x107 7.98
P. aeruginosa 5.6x108 40 u.1_ 2.2x107 6.34
S. aureus 2.4x109 40 u.1_ 9.6x107 7.98
K. pneumoniae 1.1x109 40 u.1_ 4.3x107 7.60
S. typhimurium 2.4x109 40 u.1_ 9.5x109 7.97
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Log Reduction
Logio
Treatments (3 replicates each) CFU/Swatch (calculated
Survivors
CFU/Swatch)
E.coli 1-1 190 2.27 5.71
E.coli 1-2 212 2.32 5.66
E.coli 1-3 199 2.29 5.69
P.aeruginosa 1-1 <10 <1.0 5.34
P.aeruginosa 1-2 <10 <1.0 5.34
P.aeruginosa 1-3 <10 <1.0 5.34
S aureus 1-1 <10 <1.0 6.98
S aureus 1-2 <10 <1.0 6.98
S aureus 1-3 <10 <1.0 6.98
K. pneumoniae 1-1 TNTC N/A N/A
K. pneumoniae 1-2 TNTC N/A N/A
K. pneumoniae 1-3 TNTC N/A N/A
S. typhimurium 1-1 <10 <1.0 6.97
S. typhimurium 1-2 <10 <1.0 6.97
S. typhimurium 1-3 <10 <1.0 6.97
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[0027] These examples demonstrate that the process of the present invention
effectively destroys
pathogens in textiles. Further this is accomplished using a low temperature
wash and a low temperature
bleach which significantly reduces energy costs, as well as time required,
because there is no need to
have the step down cooling to prevent wrinkles. Thus, the present invention
provides not only an
effective method to destroy pathogens and textiles, but at the same time
reduces costs and laundry
time. This has been a description the present invention, however, the
invention itself should only be
defined by the appended claims.
