Note: Descriptions are shown in the official language in which they were submitted.
Ed
AYE
METHOD AND TABLET FOR SANITIZING TOILETS
. _ _
FIELD OF THE INVENTION
-
This invention relates to sanitizing and
disinfecting flush toilets. More particularly, this
invention relates to automatic toilet bowl cleaners.
BACKGROUND
A number of different compositions and
methods for disinfecting flush -toilets have been
proposed. These include various hypochlorite and
chloramine compounds, that can be dispensed from a
single-compartment dispenser, such as is described
in US. Patent 4,318,891, or from a two-compartment
dispenser such as is described in US. Patent
3,618,143 or 4,208,746. The disinfecting composition
can be employed as granules, but is more commonly
employed as a tablet.
In order to act effectively in automatic
toilet bowl cleaners, the disinfectant tablet must
have a number of properties. The tablet should
- 20 produce a disinfectant concentration from about 2 to
about 30 parts per million, preferably from about 5
to about 20 parts per million, per flush. The tablet
must not produce objectionable chloramine or other
objectionable odors. The tablets must retain their
integrity throughout the useful life of the toilet
bowl cleaner and must not crumble or disintegrate so
as to plug the various holes and passages in the
dispenser, through which water is circulated as the
toilet tank fills and drains.
.,. . .
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The most commonly used disinfectant tablet
materials are calcium hypochlorite and trichloroiso-
cyan uric acid. Each of these substances has major
drawbacks. Calcium hypochlorite contains insoluble
components that can plug the holes in the dispenser, and
also contributes to water hardness and scale formation
by adding calcium ions to the water. Trichloroiso-
cyan uric acid is a strong acid and can produce objection-
able chloramine odors under some circumstances.
A disinfectant tablet that produces an
appropriate concentration of disinfectant, with the
requisite lifetime and tablet integrity, and without the
negative properties discussed above would be an advance-
mint in the art.
SUMMARY OF THE INVENTION
. .
This invention provides a tablet suitable for
disinfecting a flush -toilet, comprising an alkali metal
salt of dichloroisocyanuric acid, preferably sodium
dlchlorolsocyanuric cold dehydrate, and a chloride salt
selected from the group consisting of calcium chloride
and barium chloride, preferably calcium chloride
dehydrate and barium chloride dehydrate, in which the
molar ratio of alkali metal dichloroisocyanuric acid
to chloride salt is no greater than 4:1, preferably
no greater than 3:1, and most preferably substantially
stolchlometric. The tablet preferably contains at
least about 40% alkali metal dlchloroisocyanuric acid
more, preferably at least about 50%, and most prefer-
ably at least 60%. The table-t also preferably contains
a mold release agent, such as boric acid or moo-
glycerol Stewart. This invention also provides a
method for disinfecting a flush toilet comprising
contacting a tablet as described above with the water
provided to flush the toilet, particularly where the
water provided to flush the toilet is contained in a
tank that is part of the toilet.
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DESCRIPTION OF THE INVENTION
Jo
The use of alkali metal salts of dlchloro-
isocyanuric acid in tabulated toilet bowl disinfects has
a major drawback in that their volubility in water is
large enough so that the tablets do not have sufficient
lifetime. The tablets of this invention reduce the
volubility of the alkali metal salt of dichloroiso-
cyan uric acid by providing barium and calcium ions that
can react with the dichloroisocyanuric acid to form
either barium di(dichloroisocyanuric acid) or calcium
di(dichloroisocyanuric acid). These diva lent metal
salts are less soluble than the alkali metal-salts, and
the tablet exhibits this lower volubility. In short,
the tablet behaves as though it were made, at least in
part, of barium di(dichloroisocyanuric acid or calcium
di(dichloroisocyanuric acid), instead of the more
common, and less costly, alkali metal salts of dichloro-
isocyanuric acid.
In theory, this same approach ought to work
with a variety of diva lent metal salts. However, the
formulation must be tablet table in order to be useful
with the dispensers that are commonly used with toilet
bowl cleaners. The dispenser normally includes a con-
trainer for the disinfectant tablet with openings or
passages through which water flows during the flushing
cycle In this way, the tablet becomes partially or
fully immersed in water, and dissolves to release the
disinfectant. This solution is dispensed to the
toilet during flushing. This type of dispenser is disk
closed in US. Patent 3,618,143 and US. Patent
4,208,747.
In this type of dispenser, and other dispensing systems,
it is necessary that the tablet maintain its integrity,
so that water can flow around the tablet to get the
appropriate dissolution of disinfectant, and so that
the openings and passages do not get clogged. The
I
I AYE
formulations of this invention form tablets that do not
disintegrate in water as do many other formulations
containing other diva lent metal compounds. This tablet
integrity is central to the operation of this invention.
The tablets of this invention are particularly
suited to use in dispensers of the type discussed above,
but can also be used with other disinfecting systems
where tablet integrity is either necessary or desirable,
such as "under the rim" toilet bowl cleaners, in which
lo flushing water washes over a tablet hung under the
toilet bowl rim.
The alkali metal salt of dichloroisocyanuric
acid that can be used with this invention can be either
potassium or sodium, with sodium being preferred. It
is also preferred that the alkali metal salt of
- dichloroisocyanuric acid be fully hydrated. Sodium
dichloroisocyanuric acid dehydrate is the most preferred
species It is preferred that the tablet be at least
about 40% by weight, more preferably at least about 50%
and most preferably at least about 60% by weight
alkali metal salt of dichloroisocyanuric acid.
In order for the tablets of this invention to
function, there must be sufficient barium chloride or
calcium chloride to convert a substantial portion of the
alkali metal salt to the calcium or barium salt. Good
results are obtained when the mole ratio of dichloro-
isocyanuric acid to barium or calcium is no greater than
4:1, preferably no greater than 3:1, most preferably no
greater than 2:1 (which is the stoichiometric amount).
It is also possible to use an excess of barium chloride
or calcium chloride.
In addition to the ingredients discussed above
the tablets may also contain additional ingredients.
Trichloroisocyanuric acid may be added to increase the
amount of available chlorine in the formulation.
"Available chlorine" is a commonly used term which means
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the amount of active chlorine by weight in a keeps-
lion compared with the amount of active chlorine by
weight in chlorine gas, expressed as a percent. If the
amount of trichloroisocyanuric acid in the composition
is too large, objectionable chloramine odors can be
produced The tablets may contain tabulating aids, such
as lubricants, mold release agents, binders, etc. The
most commonly used mold release agents are boric acid
and monoglyceryl Stewart. It is preferred that the
formulation contain about 2% mold release agent. The
formulation may also include a filler, such as sodium
chloride. The filler can act to reduce volubility,
assist in tabulating, or perform other functions.
It is preferred that all of the components of
the formulation be fully hydrated, so that hydration
does not occur after tabulating, which can be harmful
to tablet integrity.
The tablet of this invention can either be
used alone, to provide disinfection of the toilet bowl,
or, preferably, in combination with another tablet that
provides a detergent or surfactant, a perfume, a dye,
and the like, to provide more complete toilet bowl
cleaning.
The following Examples are intended to thus-
irate this invention, and are not intended in any
limiting sense In the Examples, as well as in the
discussion above, all parts and percentages are by
weight, unless otherwise specified.
EXAMPLES 1 - 8
Tablets were prepared with 1.75 inch (3.8 cm.)
diameter on a press at 9100-9800 psi (62,700 - 67,500
spa) of pressure. The tablets contained 33 g with the
compositions indicated. Sodium dichloroisocyanuric
acid dehydrate (NaC12CYA OWE) was used as the alkali
metal dichloroisocyanuric acid. Additionally, each
tablet contained 1% H3BO3 and 0~5% monoglyceryl
,
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Stewart, to act as mold release agents. The tablets
were placed in a dispenser similar to that described
in US. Patent 4,208,747, and the dispenser was placed
in a container of water To simulate flushing of a
toilet, the dispenser periodically was raised out of
-the water and allowed to drain. The amount of active
chlorine dispensed was determined amperometrically,
and the concentration, in parts per million released
to a toilet was estimated and reported as "Pam
Chlorine". The lifetime, in days, was also estimated.
Many tablets swelled and disintegrated, so these data
were not available.
The results are reported in Table I.
TABLE I
. _
15 Example Est.Life-
Number Composition Pam Chlorine time Days
1. 66% NaC12CYA~2H2O 3 - 4 30
33% Buick
2. 74% NaC12CYA-2H2O 19 -24 30
25% Buick
3. 74% NaC12CYA-2H2O 4 -20 14
25% Cook
JO 74% NalC12CYA-2H2O tablet
25% Cook disintegrated
5. 7 % Nay SUE 2 tablet
25% McCoy OWE disintegrated
6. 66% NaC12CYA~2H2O tablet
26% McCoy OWE disintegrated
7% Nail
7. 74~ NaC12CYA OWE tablet
25% SrC12~2H2O disintegrated
8. 74% NaC12CYA~2H2O tablet
25% Zn(C2H3O2)2~2H2O disintegrated
As can be seen from the data of Table I, mix-
lures of alkali metal dichloroisocyanuric acid and
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diva lent metal compounds are very difficult to tablet.
The only compounds with which tablets could success-
fully be made are barium chloride and calcium chloride.
EXAMPLES 9 - 12
Tablets were made in similar manner, with
similar diameter to those in Examples 1 - 8, except
that 50 g of the composition was used. Tablets were
prepared using barium chloride and calcium chloride,
and sodium dichloroisocyanuric acid at the indicated
percentages along with 1% H3BO3 and 1% monoglyceryl
Stewart. The tablets were placed in a dispenser
similar to that used in Examples 1 - 8, which was
placed in the tank of a standard flush toilet,
adapted -to flush automatically approximately hourly.
Samples of the water were taken periodically and were
analyzed as in Examples 1 - 8 for chlorine concentra-
lion in parts per million reported as "Pam Chlorine",
and the lifetime of the tablets was determined,
assuming approximately 10 flushes per day. The
results, along with the mole ratio of NaC12CYA OWE
to barium or calcium, are shown in Table II.
TABLE II
En, Mole Pam lifetime
No, Composition RatioChlorine(days)
9. 74% NaC12CYA-2H2O 2.94 3 - 20 ~30
24% Buick
10. 66% NaC12CYA OWE 1.98 3 - 6 ~20
24% Buick OWE
11. 74% NaC12CYA OWE 1.77 6 - 34 8
32% Cook
12. 76% NaC12CYA OWE 1.98 - 2
22% Cook
Each of the tablets maintained its integrity
throughout the test. The lifetime of the tablets,
particularly those using calcium chloride was shorter
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than the 30 days sought for most commercial toilet
bowl cleaners This could be remedied by increasing
the size of the tablet, adding a filler to decrease
sealability of the tablet, or both. By making these
fairly minor adjustments, a toilet bowl formulation
could be made to take advantage of the good tabulating
characteristics of these formulations.
