Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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WATER- REPELLANT INSECTICIDE FOR TENT FABRIC
SPECIFICATION
This invention relates to the fini~hing of fabric and more specifically to the fini~hing of fabric in a
manner to provide the fabric with effective water-repellant and insecticidal properties.
It is known to treat fabrics with protective coatings of water repellants, flarne retardant chemicals,
mildewcide, and insecticides or combinations thereof. The applications of these products have
undergone extensive use in exterior applications such as tent fabrics, awnigs, clothing, etc. U.S.
Pat. Nos. 4,833,006 and 5,198,287 and 5,252,387.
A synthetic pyrethroid permethrin is known for its repellant as well as knockdown and kill
activity. Permethrin effectively controls a variety of pests, such as ticks, cockroaches, houseflies,
mosquitoes, and other insects/arthropods. Permethrin has had very limited use in weathered
applications due to its decomposition into a nonactive, non-insecticidal product in the presence of
oxygen and ultraviolet light.
EVERCIDE~Permethrin m~m1f~ctllred by McT ~lghlin Gormley King Company contains
perrnethrin combined with other pyrethroids or natural pyrethrins and synergists. This
co"~bh~alion provides fast knockdown and sure kill. All products used in this insecticide are of
low hazard to man and domestic ~nim~1~7 and are virtually odorless and pleasant to use.
Various attempts have been made to stabilize the permethrin in the presence of degrading
elements by using encapsulation methods or various coating techniques.
U.S. Pat. No. 4,056,610 (11/1997) to Barber, Jr. et al. discloses a microcapsule insecticide
composition with a polyurea shell having U.V. absorbing compounds, in which a pyrethroid
permeates a porous shell wall and m~int~in~ an effective level of the pyrethroid upon the outer
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surface of the shell wall to control insects up to four days. Control is achieved by killing insects
which contact the pyrethroid released through the capsule wall. For this purpose the capsules are
spread out in various ways and are incorporated into sheet materials such as tapes.
U.S.Pat. No. 4,765,982 (8/1988) to Ronning and Gregg discloses an insect control device
comprising a plurality of rough-surfaced cellulosic fibers, made from a graft copolymer cellulose
and an etylenically unsaturated material copolymerizable with cellulose. Wherein a liquid
insecticide composition microencapsulated in a capsule, whose shell is perrneable to the liquid
insecticide is self-adhered to the surface ofthe fibers. The plerelled microencapsulated insect
control agents for use in Ronning's invention are those disclosed in U S. Pat. No. 4,056,610 to
Barber.
Ronning's insecticide treated, rough surfaced cellulosic fibers are formed into webs, tapes, sheets,
pads, and various other relatively flat shapes to maximize the surface area of the device. These
devices are made suitable for use in particular locations, such as a circular sheet for the top of a
silo or a ribbon-like tape for placement along the base of a building or door.
Ronning teaches that smooth-surfaced synthetic fiber-forming materials such as polyester and
nylon do not act as good sites for adhesion of microencapsulated insect control agents. Ronning' s
rough-surfaced cellulosic fibers treated with an insecticide are not suitable for a tent fabric. The
texture of the rough surfaced fibers is not s~ti~f~ctory and they are neither water repellant or flame
retardant.
U.S. Pat No. 4,833,006 (5/1989) to Mc. Kinney discloses a flame resistant and water-repellant
coating for fabric that contains a polyfunctional isocyanate as an adhesion promoter and binder to
adhere the coating to the substrate in a flake proof manner. For this purpose, the coating
compositions are preferably applied in a liquid state to the fabric and then processed at a
temperature of 190~C (375~F) to fuse the coating composition to the fabric substrate
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U.S. Pat No. 5,198,287 (3/1993) to Samson disGloses a tent fabric which is coated in a sandwich
structure. The fabric is coated on the outside with a water-repellant flame resistant coating, and
the inside is coated with a di~l enl water-repellant flame resistant coating in which permethrin is
incorporated at a concentration of 2.58 g/m2 active. It is prerelled that the outside coating be the
described and claimed coating in U. S. Pat. No. 4,833,006
U.S. Pat No. 5,252,387 (10/1993) to Samson is an improvement to U.S.Pat. No. 5,198,287 by
using external barriers to prevent migration of the permethrin to the outside surface. These
barriers include polymeric coatings, films, foils, fabrics, and surface treatments which are resistant
to plasticizer migration.
Samson' s sandwich type coatings mentioned in U. S. Pat No. 5,198,287 and U. S. Pat No.
5,252,387 are Im~ui~l le for small nylon type hiking tents. In small hiking tents, people may be
more frequently in contact with the tent fabric then in large tents where people can roam freely in
an upright position. Because of this, the concentrations of permethrin should be closer to 1.25
g/m2, which is the accepted limit by the environm~nt~l Protection Agency (E.P.A) for use on
commercially treated clothing. On light-weight hiking tents this coating will affect the feel and the
breathability of the fabric, thus the fabric will appear stiffer and will not permit moisture to
permeate through the fabric to the outside of the tent. Because of the confined space within the
tent, in cool weather con~çn~tion will form on the inner walls and may wet other items, for
example sleeping bags, which touch the outer wall.
U.S. Pat No. 5,503,918 (4/1996) to Samson combines permethrin with polyvinylacetate and U.S.
Pat No. 5,089,298 (2/1992) to McNally combines permethrin with amylopectine, both of these
treatments require a two step process in order to treat clothing such as battle dress uniforms
(BDU). Neither of these processes is suitable for lightweight hiking tents since neither provides; a
one-step application or water-repllancy.
Fn~lling on the issuance ofthe above mentioned patents, research has continued for effective use
of permethrin in repelling mosquitoes and other insects, which may carry diseases.
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In the Past According to the Navy medical guide of 1984, the US Army suffered over 50,000
casualties due to malaria during the Vietnam conflict. (US Pat 5,503,918)
Nowadays, because backpacking is becoming even more popular in areas where malaria is present,
a search for a safe, efficient, inexpensive easy to apply water-repellant insecticide for use by
individuals on small lightweight hiking tents is needed.
It is the primary purpose of this invention to treat light-weight hiking tent fabric homogeneously in
a one-step application, with a water-repellant and insecticide finish, that will not affect the fabric
properties, and will have a duration of at least 60% of the fabric life. This invention provides a
safe, efficient, inexpensive, easy to apply water-repellant insecticide for use by individuals on small
lightweight hiking tents or other substrates that may require these features.
Figure 1. is a perspective view of the tent
Figure 2. is a sectional view taken substantially along the line A-A in figure 1.
Figure 3 . is a chart illustrating the durability of the product by demonstrating the percentage of
mosquitoes dead or unable to fly with respect to the bright-s-ln~hine hours of exposure and the
fabric life/strength r~m~inin3~
The fabric or substrate suitable for this invention can be any light weight fabric suitable for the
m~mlf~cture oftents or structures of limited size.
Applicants treat the light-weight hiking tent fabric or substrate with a low concentration of the
insecticide EVERCIDE~Perrnethrin combined in solution with an air-drying, air-curing silicone
fabric finish which serves as a water-repellant. This solution impregnates the fabric in a
homogeneous manner, and provides water-repellancy and insecticidal properties without affecting
the breathability or the feel of the fabric. This treatment will cure at room temperature and can be
applied using a hand pumpspray, aerosol or paintbrush to the tent, or during normal commercial
finish operations on the m~mlf~ctured fabrics.
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The following composition is exemplary of the solution that can be used in practice.
EXAMPLE 1
Water-repellant with insecticide for treating light-weight tent fabric.
COMPONENT PERCENTAGE FUNCTION
Polysiloxane in solvent 7.00 Water-repellant
(Dow Corning C2-0563 Repellant)
Permethrin 0.63 Insecticide
(Evercide 80% conc.)
Odorless Mineral Spirits 92.37 Solvent
100.00 %
Ultra violet radiation along with Oxygen (~2) are the major components associated ~,vith
weathering degradation. A water-repellant coating, must repel water, it therefore helps prevent
oxygen in moisture to come in contact with and diffuse into fibers or coating, thus redllçing the
rate of degradation. If this coating also has natural U.V. absorbing properties, which can further
be enhanced by additives, it may be possible to reduce the degradation rate of the fabric or coated
products. The application method, water-repellant coating durability, and U.V. properties ofthe
water-repellant are also a concern.
The silicone finish is very stable in the presence of U.V. radiation and in addition to serving as a
water-repellant, the silicone finish acts as a plasticizer by coating the permethrin and creating a
permeable shell around the permethrin. The silicone finish prevents the permethrin from degrading
rapidly while providing a sustained release of the insecticide to the fabric.
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The water-repellant insecticide solution will be applied to the outside of the tent illustrated in
figure 1. The solution can be applied to a tent using a hand pulllpspl~y, aerosol or paintbrush.
Application of the solution would be hazardous inside the tent due to the restricted space and wall
inclination. Unfini~hed tent fabric/substrate can be commercially treated during normal industrial
finish operations. The solution should be applied in a fashion that completely saturates the fabric as
illustrated in figure 2. Such a homogeneous application will deposit approximately 0.25 g/m2 of
permethrin within a light-weight tent fabric. This amount corresponds to 10.3 times less
permethrin then applied to tents treated by Samson U.S. Pat. No.5,198,287 and 5 times less then
accepted level allowed on clothing by the E.P.A.
The effectiveness of the permethrin as an insecticide has been field tested for a duration of 163.1
bright sun~hine hours in the months of July and August. Measurement of bright sunshine hours or
U.V.-B radiation provide a better method for measuring degradation caused by weathering
exposure than months or days of exposure, because they do not take into account the shorter days
of winter, and rainy days when the rate of degradation is reduced.
The water-repellant insecticide was evaluated using mosquitoes to determine:
i ) That the natural behaviour of the mosquitoes to land on the walls of the tent would not be
influenced by the insecticide repellant properties of the permethrin.
ii ) The number of mosquitoes dead or unable to fly (knockdown, KD) inside the tent after an
exposure of three hours.
iii) The duration of insecticide tre~tment when exposed to weathering.
In the case of i) mentioned above, if the permethrin repelled the mosquitoes, the mosquitoes
would try and land on non-treated material such as clothing articles or people inside the tent, thus
increasing the chances of biting.
Two dark brown light-weight hiking tents with a total surface area of 4.81 m2 were erected in an
open field without shade during the months of July and August to obtain the maximum effect of
elevated temperatures and U.V. radiation, both of which increase the rate of degradation. Because
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the sun rises in the east and sets in the west, (northern hemisphere) the tents were oriented with
the door facing due south so as to m~ximi7e the surface area of fabric exposed to solar radiation.
A non-coated light-weight hiking tent fabric was also exposed due south, to determine the life time
of the fabric.
Weekly bioassays were conducted with mosquitoes. Each week mosquitoes were released inside
the tent and left for a period of three hours, during which their behaviour was studied, as well as
the time until the first KD occurred.
We found that the treated fabric showed no insecticide repellant effect but excellent insecticide
properties and that the natural behaviour of the mosquitoes remained unaltered. Once released
inside the tent, the mosquitoes immediately flew and held to the roof and walls of the tent and
remained there without the need to move around. After a period of about fifty mimltes the smaller
mosquitoes began to lose grip, and eventually fall to the floor, while the larger ones began to show
signs of intoxication. After the exposure of three hours the mosquitoes dead or alive were
counted. The untreated tent showed no dead mosquitoes within the three hour time frame. After
the tent had been exposed for 161.3 hours, 243 mosquitoes were let free inside the tent, of which
95% died in the first three hours.
Figure 3 . is a chart illustrating the durability of the product by the percentage of mosquitoes dead
or unable to fly with respect to the bright-sl m~hine hours of exposure and the fabric life/strength
r~nn~ining
It was noticed that after 1 63 .1 hours of bright sunshine hours of exposure the water-repellancy
had dimini~hed slightly, it is therefore suggested that at this point or later, because of the safety
and simplicity of the application, that the tent be retreated to maximize the eff1ciency of both the
water-repellant and insecticide properties. Protection by the water-repellant insecticide coating
may be longer if the tent is exposed in; an intermittent fashion, in the shade, or in cooler times of
the year when temperature and U.V.radiation aren't as high.
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The following composition is exemplary of the solution that can be used in practice to reduce
mildew formation, on tent/substrate that are exposed to high humidity environments.
EXAMPLE 2
Water-repellant with insecticide and mildewcide for treating light-weight tent fabric.
COMPONENT PERCENTAGE FUNCTION
1. 2-n-octyl-4-isothiazolin-3-one 4.0 Mildewcide
(Rohm and Haas, Skane M-8)
2. Butyl Cellosolve .05 Carrier Solvent
3. Polysiloxane in solvent 7.00 Water-repellant
(Dow Corning C2-0563 Repellant)
4. Permethrin 0.63 Insecticide
(Evercide 80% conc.)
5. Odorless Mineral Spirits 87.42 Solvent
6. Zinc Oxide (Ultra fine) 0.9 Mildewcide/U.V. blocking
100.00 %
For best efficiency, the above formulation should be mixed in the given order. This solution can
be used in the same manner as listed in the previous example.
Fabric/substrate treated with this solution offers good mildewcide properties and may prolong
fabric/substrate life due to the natural U.V. absorbing properties of Skane M-8 and zinc-oxide
mildewcide products.
The fabric was exposed to weathering in a damp environment oriented vertically and facing due
north to maximize the growth of mildew on the surface. After three months of exposure, the
control non-treated fabric was covered with mildew, while the treated fabric showed little or no
signs of mildew.
Although specific terms have been employed in describing the invention, they are used in a
descriptive and generic sense only and not for purposes of limitation.
