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Description  |
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FIELD OF THE INVENTION
The present invention relates to hygienic articles, in particular, toilet
seat covers.
REFERENCES
"Triboelectric Charging of Common Objects", Thomas B. Jones, University of
Rochester,
http://www.ee.rochester.edu:8080/.about.jones/demos/charging.htm1,
December, 1999.
"TRIBOELECTRIC SERIES", William Beaty,
http://www.eskimo.com/.about.billb/emotor/tribo.txt, 1995.
BACKGROUND OF THE INVENTION
The problems associated with toilet seat sanitation have long been
recognized. Toilet seats contaminated with human waste, bacteria, and/or
viruses create various health risks. It has been reported that by touching
a toilet seat just one time, it takes at least five consecutive hand
washings to get rid of most of the germs and bacteria. Thus, it is not
unusual that one might catch a cold or influenza as a result of touching a
toilet. Elderly persons, immunocompromised people, chemotherapy patients,
pregnant women, young children, and people with diabetes are particularly
susceptible to toilet germs and bacteria.
Public places, such as bus stations, airports, restaurants, movie-houses,
and office buildings generally provide facilities used by large numbers of
people. It is often not practicable, nor is it practiced, to adequately
clean the toilet seat between uses. Consequently, such facilities, on the
whole, are not clean and not esthetic.
The problem of toilet seat sanitation has been addressed several ways. One
approach has been to provide a toilet seat cover that minimizes contact
between the toilet seat and a user. Such a cover can take the form of a
layer of protective material between the user and the toilet seat.
Usually, such covers define an eliptical ring which have an outer
dimension like that of the toilet seat and an inner dimension which
permits uninterrupted bowel movement and urination.
Known toilet seat covers of the above-mentioned type suffer from the
considerable disadvantage that they tend to slide off the toilet seat;
e.g., either into the toilet bowl itself, or onto the floor area near the
toilet. Obviously, this creates waste of raw materials, as a user must
utilize a fresh cover, and potentially contributes to further filth in
cases where the cover falls on the floor and is left there.
Clearly, further advancements in the art of toilet hygiene are needed.
SUMMARY OF THE INVENTION
An aspect of the present invention provides a method for improved toilet
hygiene. In an embodiment of the invention, the method comprises: (i)
treating a toilet seat cover to provide the cover with a non-neutral
surface charge; and (ii) overlaying the cover on a toilet seat, such that
the cover clings to the seat due to the non-neutral surface charge.
The method further comprises, in one embodiment, treating the toilet seat
to provide a surface of the seat with a non-neutral surface charge. In one
embodiment, the seat charge is formed by way of induced polarization.
According to an embodiment of the invention, at least 20%, at least 30%, at
least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at
least 90%, and/or at least 95% of the surface area of one side of the
cover is in intimate clinging contact with the seat. Such surface-area
percentages are considered herein to comprise a substantial portion of the
cover. In some embodiments, about 25%, or about 50%, or about 75% of the
surface area of one side of the cover can be caused to cling to the
surface of the seat for a period of time (e.g., greater than 20 seconds).
In one embodiment, the treating of the toilet seat cover comprises
tribocharging (also known as "triboelectric charging," "contact charging"
or "electrification by contact"). In another embodiment, the treating
includes passing the cover through an electric field.
Another aspect of the present invention provides a method for improved
toilet hygiene, comprising: (i) establishing a charge differential between
a toilet seat cover and a toilet seat; and (ii) overlaying the cover on
the toilet seat, such that the cover clings to the seat (due to the charge
differential).
The establishing step can be selected from the group consisting of
triboelectric charging, inducing polarization, and passage through an
electric field, among others.
In various embodiments, the charge differential is at least 50V, at least
75V, at least 100V, at least 150V, at least 200V, at least 250V, at least
300V, at least 500V, at least 750V, at least 1,000V, at least 2,500V, at
least 5,000V, and/or at least 10,000V, or higher. In an embodiment of the
invention, the charge differential is maximized.
In another of its aspects, the present invention provides a device for use
with a toilet seat, comprising a laminar (multi-layer) sheet-like material
configured to fit upon a toilet seat, and having a first outer layer on
one side and a second outer layer on an opposite side. In one embodiment,
the first and second layers are comprised of first and second materials,
with the first and second materials having unlike triboelectric properties
such that when surfaces of the first and second materials are brought into
intimate contact with one another and then separated each acquires a
non-neutral surface charge.
In its operative condition, the cover can be utilized in a sheet-like
configuration, or it can be configured into a sleeve-like arrangement
adapted to slidably fit over a toilet seat.
In one embodiment, the toilet seat cover is comprised, at least in part, of
an insulating (substantially non-conducting) material.
In one embodiment, a plurality of such sheet-like materials are releasably
connected to one another end-to-end, and are wound so as to define a roll
configuration.
In another embodiment, a plurality of such sheet-like materials are
arranged in a stack, with each sheet-like material of the stack disposed
in intimate contact with its nearest neighbors (or neighbor, in the case
of the first and last sheets). Further in this embodiment, the first layer
of each sheet-like material of the stack is disposed facing in a first
direction and the second layer of each sheet-like material of the stack is
disposed facing in a second direction, wherein the second direction is
opposite of the first direction.
One of the layers can be comprised, for example, of a paper material (e.g.,
tissue). The other of the layers can optionally be provided with adhesive
properties (e.g., a slight degree of stickiness or tackiness).
In one embodiment, one of the layers comprises an electret.
A further aspect of the present invention provides a dispensing device for
dispensing toilet seat covers. In an embodiment of the invention, the
dispensing device comprises: a compartment adapted to hold a plurality of
toilet seat covers; an orifice defined by a wall of the compartment
permitting one of the covers to be pulled therethrough for removal from
the compartment; and a charge-imparting member positioned such that a
cover pulled through the orifice must pass closely by (e.g., rub against)
the charge-imparting member. In use, a cover removed from the dispenser
via the orifice gains a non-neutral surface charge.
In one embodiment, the charge-imparting member and the covers have unlike
triboelectric properties. For example, the covers can be a paper material
and the charge-imparting member can comprise a vinyl surface.
In another embodiment, the charge-imparting member is an electrostatic
generator.
These and other features and advantages of the present invention will
become better understood with reference to the following description,
drawings, and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The structure and manner of operation of the invention, together with the
further objects and advantages thereof, may best be understood by
reference to the following description taken in conjunction with the
accompanying drawings, in which identical reference numerals identify
similar elements, and in which:
FIG. 1 is a perspective view of a toilet, suitable for practicing the
present invention, and illustrating placement of a toilet seat cover upon
the toilet seat, according to the present invention;
FIG. 2 is a perspective view that illustrates tribocharging during
unwinding of a toilet seat cover from a roll, according to the present
invention;
FIG. 3 is a partially schematic, perspective view illustrating
triboelectric charging upon peeling a toilet seat cover from a stack,
where each cover has front and back surfaces of first and second
respective materials having disparate triboelectric properties; and
FIG. 4 is a perspective view of a dispenser for toilet seat covers, having
a charge-imparting member mounted near an orifice through which individual
seat covers can be pulled, according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The following discussion of the preferred embodiments of the present
invention is merely exemplary in nature. Accordingly, this discussion is
in no way intended to limit the scope of the invention, application of the
invention, or the uses of the invention.
The present invention provides a device and method for improved toilet
hygiene. Certain aspects of the present invention provide toilet seat
covers having an affinity for toilet seats. Other aspects of the present
invention provide methods for rendering toilet seat covers in a state
wherein the covers possess an affinity for toilet seats. Related aspects
of the present invention provide toilet seats having an affinity for
toilet seat covers. Further related aspects of the present invention
provide methods for rendering toilet seats in a state wherein the seats
possess an affinity for toilet seat covers.
Various embodiments of the present invention provide for the treatment of a
toilet seat cover such that the cover acquires a non-neutral surface
charge. In addition, or in the alternative, a toilet seat upon which the
cover is to be placed can be treated to have a non-neutral surface charge.
The charging is such that the two objects experience an attractive force.
Force acts between two objects with charge, attractively between objects
with opposite charges, repulsively between objects with similar charges.
The magnitude of the force depends on the product of the two charges (in
coulombs, C) divided by the square of the distance between the centers of
charges.
F.sub.6 =kq.sup.1 q.sup.2 r.sup.2
Charles Augustin de Coulomb (1736-1806), French physicist, determined the
Coulomb constant, k=8.988.times.10.sup.9 Nm.sup.2 /C.sup.2.
Induced polarization allows a charged body to attract an initially neutral
body.
Various embodiments of the present invention exploit the phenomenon known
as "triboelectric charging," or "tribocharging" for short. This phenomenon
is also referred to as "contact charging" or "electrification by contact."
Some general principles of tribocharging will now be discussed.
When two materials with neutrally charged surfaces come into contact
(within 8 .ANG., and preferably 4 .ANG., or less) and then separate, the
materials will have undergone triboelectric charging and now be at a
non-neutral surface charge level. The level and polarity this newly
acquired surface charge is at is dependent on several factors, but can be
relatively answered by reference to a triboelectric series chart (i.e., a
ranking of a material's polarity when triboelectrically charged with a
given material), such as shown in Table 1.
TABLE 1
TRIBOELECTRIC SERIES
Human Hands <---- Most Positive (acquires a more positive
Asbestos charge; Lower work function)
Rabbit Fur
Acetate
Glass
Mica
Human Hair
Nylon
Wool
Fur
Lead
Silk
Aluminum
Paper
Cotton ------ ZERO
Steel
Wood
Amber
Sealing Wax
Hard Rubber
MYLAR
Nickel, Copper
Silver
UV Resist
Brass, SS
Gold, Platinum
Sulfur
Acetate, Rayon
Polyester
Celluloid
Styrene (Styrofoam)
Orlon
Acrylic
SARAN
Polyurethane
Polyethylene
Polypropylene
Vinyl (PVC)
KEL F
Silicon
Teflon
Silicone Rubber <----- Most Negative (acquires a more negative
charge; Higher work function)
For example, a material such as glass that comes into contact with a vinyl
material will acquire a more positive charge because it is near the `more
positive` position in the triboelectric series chart relative to the
position of vinyl. Alternately, the vinyl will acquire a more negative
charge following the same logic. The fact that these two materials are far
apart from each other in the series may result in a larger charge level
generated than if the glass came into contact with, for example, aluminum.
It should be appreciated that the terms "triboelectric charging" (or
"tribocharging"), "contact charging" and "electrification by contact" are
particularly apt, as they avoid giving the idea that the mechanism for the
electrification is caused by friction. In this regard, it is noted that
the term "frictional electrification" is misleading. Separation of charges
is not accomplished by friction per se. When surfaces come together
chemical bonds can form. When surfaces in contact are separated, the bonds
can rupture, and any asymmetrical bonds (such as ionic bonds) will tend to
leave imbalanced charges behind.
There are several mechanisms that contribute to the resulting charge that
is generated by the triboelectric process. There appear to be four major
factors that have the greatest influence on the triboelectric charging
process, and they are: surface contact effects; work function; charge back
flow; and gas breakdown.
Surface contact effects include the surfaces roughness, contact force, and
frictional heating (caused by rubbing), all of which influence the amount
of surface area that is in contact with the other material during
tribocharging. The greater the surface contact, the greater the resulting
net charge may be when two surfaces are separated after contact.
Though surface contact may seem rather intuitive, there are some subtleties
that should be elaborated on; one being surface friction, the other
surface roughness. When the coefficient of friction between two surfaces
increases, this indicates that the surface roughness between the two
surfaces may be greater, which results in decreased surface contact. As an
illustration, when two surfaces are brought together, e.g., over about 1.0
square inch, the actual or physical contact may only be about 0.2 square
inches because of surface roughness. Upon pressing the surfaces together,
the contact area may increase to about 0.4 square inches, depending on the
force of pressing and, again, the surface roughness of both surfaces. If
both surfaces were polished to an extremely smooth and flat area
(micro-polished), the contact area may be further increased to about 0.8
square inches. The smoother either surface is, the more contact both
surfaces will make with each other resulting in possible increase of the
exchange of charges.
Surface charge imbalance is related to friction in that both are dependent
on the adhesion between two surfaces on the molecular level. Two surfaces
may stick together because chemical bonds form on the surface. When
surfaces in contact are separated, some bonds may rupture, and any
asymmetrical bonds will tend to leave imbalanced charges behind. Which
surface bonds rupture is dependent on their work function. The work
function is the property of a material's ability to hold onto its free
electrons (the electrons orbiting the outer most shell of the material).
The greater the material's work function, the less likely it is to give up
its free electrons during contact (triboelectric generation). The weaker
the work function is, the more likely the material will acquire a more
positive charge by giving up or loosing some of its free electrons. In
general, materials with higher work functions tend to appropriate
electrons from materials with lower work functions.
Charge backflow occurs when two materials have been charged, e.g., from the
above mechanisms, and are then separated from intimate contact. The
backflow of some of this charge imbalance may flow back to the original
material reducing to some degree the net charge (charge imbalance) on
either surface from tribocharging.
Gas breakdown can occur between two surfaces during separation. The
microscopic surface topology of a surface has many peaks and valleys. It
is one of these peaks that may have substantial charge that yields a large
electric field in a very small area causing corona discharge or the
breaking down of the air molecules which were acting as a dielectric
(insulator between the two separating surfaces). During this breakdown,
charge can be transferred from one surface to the other via the path of
the electrified air (plasma). The amount of charge transferred is
dependent on the distance of separation and the gas(ses) pressure(s).
In embodiments of the present invention, conditions leading to charge
backflow and/or gas breakdown are to be minimized or avoided.
Standard cellulose tape is a good example of a material that has a strong
surface adhesion and consequential large surface area contact typically
resulting in large charge imbalance during unwind or removal. During
unwind, the contact and separation of the tape to itself results in
triboelectric charging. An important contribution to the large imbalance
of the tape during unwind is the difference in materials comprising the
tape. Typical tape films are cellulose, and the adhesives are often rubber
based. The two are spaced far enough apart in the Triboelectric Series to
result in defined polarities, see Table 1. The rubber adhesive will
acquire a more positive charge and the cellulose will acquire a more
negative charge due to the difference in their work functions. Voltages
well over 20 kV are easily measured from this type of tape.
In accordance with various embodiments of the present invention, a toilet
seat cover ("cover") is tribocharged before it is finally placed on a
toilet seat ("seat") and sat upon. The charge established on the cover
provides a "cling" characteristic that assists in maintaining the cover in
place once situated on the seat.
The present invention can be practiced in connection with a wide variety of
toilet seats, provided that the material comprising the toilet seat top is
such that a charge separation can be maintained, at least until such time
that a user becomes situated on the cover and, preferably, throughout at
least most of the period of use. In various embodiments of the invention,
the affinity between the toilet seat cover and toilet seat is sufficient
to maintain the cover in intimate clinging contact with the seat for at
least 10 seconds, at least 15 seconds, at least 20 seconds, at least 30
seconds, at least 45 seconds, and/or at least one minute.
Toilets are typically formed with a bowl having an upper elliptic rim
defining a generally horizontal plane. A seat is usually associated with
the toilet and is supportable on the rim, permitting a user to sit above
the bowl. For example, FIG. 1 shows a toilet 8 having a bowl 10, an upper
rim 12, and an essentially annular toilet seat 14. Seat 14 is configured
for pivotal movement at its rearward end to allow tilting up and down. It
should be noted that the words "essentially annular" are intended to
include any seat shape, such as oval, ring-like, elongated, horse-shoe
shape, or the like, and encompasses both open-front and closed-front
seats. In FIG. 1, seat 14 is an open-front seat.
In certain embodiments, covers of the present invention generally have an
inner and outer radius substantially like that of a seat with which they
are likely to be used. The cover can be incorporated into a square or
rectangular sheet, and adapted to be separated from nonessential pieces or
regions of the sheet just prior to use. For example, perforations or
scoring can allow the cover to be readily torn from the sheet. It should
thus be appreciated that a great variety of shapes are contemplated herein
for a cover of the invention. For example, a cover of the invention can
mimic the design of a large elongated oval toilet seat, a relatively small
slightly elongated oval toilet such as is frequently found in outhouses,
or essentially any other shape of toilet seat.
In one embodiment, a toilet seat cover is treated to provide the cover with
a non-neutral surface charge. As shown in FIG. 1, the cover 20 can then be
laid upon a toilet seat 14, such that the cover clings to the seat.
In certain embodiments, a toilet seat cover, such as 20, according to the
present invention, is macroscopically two-dimensional and planar, although
not necessarily flat. The toilet seat cover 20 may have some thickness in
the third dimension. However, the third dimension is very small compared
to the first two dimensions.
According to certain embodiments, toilet seat covers according to the
present invention are configured to exhibit good drapability. Drapability
is the tendency of the toilet seat cover to conform, normal to its plane,
to a surface, such as a toilet seat upon which the toilet seat cover is
placed. The higher the drapability of the toilet seat cover, the more
accurately it will conform to the surface. More accurate conformation to
the surface can provide greater retention thereon.
The covers of the present invention can be especially advantageous when
used with contoured seats; a situation where prior art toilet-seat covers
often fail. Having a sufficient surface charge, the cover will cling to
the contours of the seat.
In various embodiments of the present invention, a toilet seat cover is
comprised of a material ranking higher in the triboelectric series (i.e.,
closer to the "most positive" end) than the material comprising a toilet
seat in connection with which it is to be used. For example, a toilet seat
cover of the present invention comprised of a paper material, e.g., a soft
tissue-type paper, can be well suited for use with a toilet seat comprised
of polyethylene, polypropylene, Lucite acrylic, ABS plastic, or the like.
Of course, this example is not limiting, as many combinations of materials
can be selected, using the principles provided herein as a guide,
permitting one to realize the benefits of the present invention.
With regard to the selection of cover and seat materials, various
embodiments of the present invention provide that one should choose two
materials that are relatively far apart on the triboelectric series (e.g.,
separated by at least 3, 5, 7, 10, or more entries [with reference, for
example, to Table 1]). In one embodiment, the surfaces of the toilet seat
cover and toilet seat that will be adjacent one another upon placing the
cover on the seat are comprised of different materials, with one of the
materials being located towards the "more positive" side of the "zero"
line in the triboelectric series, and the other material being located
towards the "more negative" side of the "zero" line in the triboelectric
series (See Table 1).
One embodiment provides that the only limitation on the material comprising
the toilet seat is that it not significantly disrupt a surface charge of
the cover. For example, the toilet seat should not be a good electrical
conductor.
It should be noted that the order of materials in the triboelectric series
is not strict or invariable. A material might shift up or down an entry or
two depending upon the conditions of the particular materials involved and
their local environment. Moreover, the present invention is not limited to
those materials set out in Table 1. Rather, the present invention
contemplates a methodology of determining materials suitable for use
herein by testing selected materials with one another for tribocharging
efficiency and efficacy. The materials of Table 1 can be used as a guide,
or yardstick, in selecting types of materials and predicting where such
materials might rank in the series. However, an ultimate decision on the
suitability of any particular material(s) is best made by simply testing
the materials with one another.
A charge differential between the cover and the toilet seat can be
established in a variety of ways. For example, the cover can be placed in
contact with the seat, then removed, thereby tribocharging the cover. Such
charging will be most effective where the topside of the toilet seat is
generally flat (planar) so that good surface contact can be made between
the toilet seat and the cover prior to separation.
In one embodiment, it is preferable that the materials comprising the cover
and seat be capable of attaining intimate contact over a relatively large
area. Thus, materials having a rough surface that hinder surface contact
should be avoided. Good surface contact between the two materials helps to
encourage strong charging when the materials are touched
surface-to-surface and then pulled apart.
FIG. 2 illustrates tribocharging during unwinding of a toilet seat cover
from a roll, according to an embodiment of the present invention. The
toilet seat cover 20, in this embodiment, is provided as a roll, in the
nature of a roll of paper towels or toilet paper, such that a user
partially unwinds the roll, e.g., in the direction of the arrow, to obtain
the next-available cover which is then torn from the roll; e.g., aided by
a perforation line or scoring, as at 26. In one embodiment, to assist in
tribocharging, the cover is a laminate article comprising upper and lower
sides of different materials with a spaced-apart ranking in the
triboelectric series. For example, one side of each cover on the roll can
be a paper-based tissue-type material, and the other side can be a
rubber-based film layer, so that tribocharging occurs upon unrolling in a
fashion analogous to the tape-dispenser example above. In one such
embodiment, the rubber-based film layer has a slight degree of stickiness
or adhesiveness, to enhance surface charging, and avoid out-of-control
unrolling, upon unwinding to remove a cover from the roll. Of course, the
adhesiveness is preferably not so great as to prevent removal of a cover
from the roll, or to cause tearing. A dispenser in the nature of an
elongated rod can be utilized to receive the roll of FIG. 2 thereover, in
a manner permitting unwinding of the roll thereabout.
Similarly, a roll of toilet seat covers of the present invention can be
configured to work with automatic or motorized seat covering devices. For
example, a roll of covers can be provided on a supply roll, with the
covers adapted to pass over the toilet seat for winding on a take-up roll.
The present invention can be configured, for example, for use in devices
such as disclosed in U.S. Pat. Nos. 5,913,609; 5,685,024; 5,561,867;
5,937,448; 6,076,198; 6,212,693; and/or 5,253,372; each of which is
incorporated herein by reference. The present invention can also be used,
for example, in automated devices such as disclosed in PCT patent
application Ser. Nos. WO 99/38427, WO 87/07492, and/or WO 88/10086; each
of which is incorporated herein by reference.
FIG. 3 is a partially schematic illustration of a further embodiment of the
present invention. Here, a plurality of toilet seat covers are arranged in
a stack, denoted generally as 30. Each cover of the stack is disposed in
intimate contact with its nearest neighbors (or neighbor, in the case of
the first and last sheets). In one embodiment, a biasing mechanism is
provided to keep the covers in pressing engagement. Each cover is
comprised of at least two layers. The two layers are comprised of
materials differing from one another with respect to their triboelectric
properties. A first outermost layer of each cover of the stack is disposed
facing in a forward direction and an outermost layer on the opposite side
of each cover is disposed facing in a reverse direction. Triboelectric
charging is effected upon peeling a toilet seat cover 20 from stack 30.
Attention is directed to the plus (+) and minus (-) signs in FIG. 3,
indicating positive and negative surface charges upon peeling.
Conveniently, the covers of the present invention can be provided for use
with a dispenser; e.g., a dispenser of the wall surface-mounted variety.
In one embodiment of the present invention, a dispenser is a bottom-fill
unit, having dimensions 153/4"w..times.11'h..times.2" deep. Such a
dispenser is typically configured to hold, for example, 250 or 500 seat
covers.
In one embodiment, a vinyl or Styrofoam member is mounted at an orifice of
a dispenser through which fresh toilet seat covers are pulled. For
example, a vinyl member can include a surface portion disposed such that a
seat cover pulled through the orifice is forced to contact it, thereby
providing a means for contact electrification. The vinyl member can be
bonded to the dispenser by means of a suitable insulating adhesive that
will not adversely affect its electrostatic properties. In another
embodiment, an electrostatic generator is mounted on the dispenser such
that it imparts a persistent electrostatic charge to a cover as the cover
is removed from the dispenser.
FIG. 4, for example, illustrates a dispenser 28 for toilet seat covers,
having a charge-imparting member 32 mounted near an orifice 34 through
which individual seat covers, such as 20, can be pulled.
The above embodiments are to be distinguished from so-called "static-cling
films," which have gained popularity in recent years in the nature of
self-sticking posters, placards, etc. for windows, mirrors, and the like.
Static-cling films are popular substrates because they adhere to smooth
surfaces without adhesives. But because of the "static-cling" moniker,
it's easy to assume that static electricity is what makes these substrates
do what they do best: apply and remove very easily, with no adhesive
residue. The truth is, conventional static-cling films have little or
nothing to do with static electricity. A heavy plasticizer load provides
the physical and chemical properties that enable them to stick to smooth,
non-porous surfaces, such as glass, polished metals, and some plastics. On
porous or irregular surfaces, however, static-cling films adhere poorly,
or not at all.
For a variety of reasons, in certain embodiments of the invention, fibrous
covers (e.g., wood pulp, cellulosic or paper-based materials, such as
tissue-type paper) are generally preferred herein. For example, such
materials are most compatible with existing sewage and treatment
facilities. Paper-based products are typically better in terms of
biodegradability. In one embodiment, a coating, e.g., a wax (preferably, a
water receptive wax) is applied to form one or more layers on a paper
sheet.
Nevertheless, the present invention contemplates that so-called "cling
films" can be used as a toilet seat cover material. Nonlimiting examples
of films include polyvinyl chloride films (whether plasticized or
flexible), polyurethane films, high density polyethylene films,
polypropylene films, tackified linear low density polyethylene films,
acrylonitrile/butadiene/isoprene films, acrylonitrile/butadiene
copolymers, styrene/butadiene copolymers (whether random or block),
styrene/isoprene copolymers (whether random or block),
styrene/ethylene-butylene block copolymers, and combinations thereof, as
well as other films known in the art for making cling films.
A "cling" property can be imparted to plastic film by including a high
content of plasticizer in the plastic. Polyvinyl chloride films with this
property are commercially available from several sources. An example of
film having a cling property is Sure-State Series 9000, which is available
from Tekra Corporation, New Berlin, Wis.
Permacharge Corp., Rio Rancho, N.Mex., provides an electrostatic
polypropylene material called ClingZ. ClingZ gets its adhesive properties
from a permanent electrostatic charge. It sticks to almost any clean
surface, including brick, chalkboards, drywall, wood, paper, carpet,
textiles, and even condensation-heavy windows and beverage coolers. The
film is repositionable like other cling films, but ClingZ contains no
plasticizers. The present invention contemplates the use of such material,
as well, in the make-up of a toilet seat cover herein.
Another embodiment of the present invention contemplates covers comprised
of electrostatically charged nonwoven fabrics.
Electrostatically charged nonwoven webs (electrets) useable in the present
invention can be made by a number of processes. U.S. Pat. Nos. 4,215,682,
and 4,904,174 disclose hot charging methods of charging hot filaments
discharging from dies in meltblowing processes for forming meltblown webs.
PCT Application PCT/US/93/0930 discloses a cold charging method for
electrostatically charging thermoplastic webs. The disclosures of U.S.
Pat. Nos. 4,215,682, 4,904,174, and PCT application Ser. No.
PCT/US/93/09630 are incorporated herein by reference for disclosing
methods, compositions, properties, and specifications of webs capable of
being electrostatically charged.
In one embodiment, a nonwoven web or fibers thereof are passed through an
electric field, preferably a sequential electric field in accordance with
PCT/US/93/09630, to impart a persistent electrostatic charge thereto.
One preferred web is meltblown, but other nonwovens such as spunbonded
fabrics can be used.
The web, prior to or after charging, can be processed through the nip of
counter-rotating rollers to compress the web and condition the surfaces.
The present invention is suitable for charging nonwoven webs prepared from
nonconductive polymeric material such as those selected from the group
consisting of polypropylene (PP), recycled and virgin polyethylene
terephthalate (PET), all types of polyethylene (PE), such as linear low
density polyethylene (LLDPE), polychlorotrifluroethylene (PCTFE),
polycyclohexyldimethylene terephthalate (PCT). In addition, the present
invention is suitable for charging composite webs containing both
conductive and nonconductive fibers such as meltblown/cotton/meltblown
thermally bonded webs or meltblown/cotton hydroentangled or needle-punched
webs, or hydroentangled mixtures of carded polyester staple fibers and
wood tissue, such as SONTARA webs (DuPont).
Another embodiment of the present invention contemplates the use of an
electrostatic generator for imparting a charge to a cover. Any of various
devices, including the electrophorus, the Wimshurst machine, and the Van
de Graaff generator, that generate high voltages by accumulating large
quantities of electric charge can be used.
Charges employed are selected to be sufficient for adherence to a selected
toilet seat, such that at least 20%, at least 30%, at least 40%, at least
50%, at least 60%, at least 70%, at least 80%, and/or at least 90% of the
cover material is in intimate contact with (i.e., appearing to be pressed
against) the surface of the toilet seat. In one embodiment, the magnitude
of the charges are as large as possible to achieve maximum cling. The
cling should last for a sufficient period of time allowing a user to
become fully situated thereupon (e.g., about 10 to 15 seconds, or more).
In one embodiment, a surface charge potential of a cover side that is to
cling to a toilet seat is in excess of 50V, in another embodiment in
excess of 100V, and in yet a further embodiment in excess of 250V. The
potential difference can be, for example, 500V; 1,000V; 2,500V; 7,500V;
10,000V; 15,000V; or greater.
The surface charge potential of a cover of the present invention can be
determined by any suitable means known in the art, e.g., by a Monroe Model
244 Isoprobe Electrostatic Voltmeter with a 1017E Probe (0.07 in. opening)
connected to a Velmex system which allows webs with dimensions up to 20
in..times.38 in. to be scanned. The measurement system can be interfaced
with an IBM-compatible PC computer using DT 3801 (I/O system (Data
Translation Inc., Marlborough, Mass.). The average value of the surface
charge potential can be computed.
Further embodiments of the present invention contemplate treating a toilet
seat cover such that it acquires a non-neutral surface charge on a surface
over which a toilet seat cover is to be placed. A toilet seat cover can
then be placed thereon. In one embodiment, the toilet seat cover is
polarized upon being brought into proximity with the toilet seat, such
that the two objects are then attracted to one another. In another
embodiment, the toilet seat cover is charged prior to being brought into
proximity with the charged toilet seat, such that the two objects are
attracted to one another and the toilet seat cover will, thus, cling to
the seat. The toilet seat can be charged by any suitable means; e.g., the
seat can be tribocharged using a material having a different ranking in
the triboelectric series; or the seat can be treated with an electric
field to establish a surface charge thereon; or the seat can be charged by
induction; etc.
Those skilled in the art can now appreciate from the foregoing description
that the broad teachings of the present invention can be implemented in a
variety of forms. Therefore, while this invention has been described in
connection with particular embodiments and examples thereof, the true
scope of the invention should not be so limited. Various changes and
modification may be made without departing from the scope of the
invention, as defined by the appended claims.
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