GB2116040A - Passive dosing dispenser containing selected calcium hypochlorite cake compositions with swelling control - Google Patents

Abstract

An article for sanitizing toilets comprising a dosing dispenser having a calcium hypochlorite cake composition housed within a reservoir, characterized in that the cake comprises an effective amount of a selected water-soluble salt. The cake is formulated such that upon contact with water it exhibits controlled swelling, i.e., it will swell less than a calcium hypochlorite cake made without said selected salt.

Description

SPECIFICATION Passive dosing dispenser containing selected calcium hypochlorite cake compositions with swelling control Technical field The most specific technology to which this invention relates is that of disinfecting devices adapted to dispense disinfectant solutions to the tank of a conventional toilet when it is flushed.

Background art Dispensers which are adapted to deliver disinfecting or aesthetic ingredients to a toilet tank to condition water in the toiler tank and bowl are known.

The following commonly-owned references will serve as background art for dosing dispensers and cakes of active ingredients used in combination therewith, and are incorporated herein by reference: U.S. Pat. No.4,171,546, Dirksing, issued Oct.23, 1979; U.S. Pat. No.4,208,747, Dirksing, issued June 24, 1980; U.S. Pat. No.4,186,856, Dirksing, issued Feb. 5, 1980; U.S. Pat. No.4,216,027, Wages, issued August 5, 1980; U.S. Pat. No.4,200,606, Kitko, issued April 29, 1980; U.S. Pat. No.4,248,827, Kitko, issued Feb. 3, 1981; U.S. Pat. No.4,253,951, McCune, issued March 3, 1981; U.S.Pat. No.4,246,129, Kacher, issued Jan.20, 1981; U.S. Pat. No.4,251,012, Williams, issued Feb. 17, 1981; U.S. Pat. No.4,247,070, Dirksing, issued Jan.27, 1981; U.S. Pat. No. 4,302,350, Callicott, issued Nov.24, 1981; U.S. Pat. No. 4,281,421,Nyquist et et al, issued Aug 4, 1981; U.S. Pat. No.4,283,300, Kurtz, issued Aug. 11, 1981; and European Pat. Appln. 0,005,286, Nyquist, published Nov. 14, 1979.

U.S. Pat. No. 4,208,747, Dirksing, issued June 1980, discloses highly effective toilet tank dispensers which receive a dose volume of water from a toilet tank in which such a dispenser is placed every time the toilet is flushed. This patent teaches that cleaning and disinfecting cakes can be used in such dispensers, but fails to address the specific problems posed by certain types of cakes, particularly when hypochlorite cakes are placed inside the reservoir of such a toilet tank dispenser. One of these problems is that a cake of calcium hypochlorite material immersed completely in the dosing liquid tends to deliver excessively high levels of chlorine. Thus, the chlorine is used up too fast.Figures 9-14 and 18 of U.S. Pat. 4,208,747, Dirksing, disclose "top-feed" dispensers in which such cakes are completely immersed in the dosing liquid. The solution is drawn from above the cake. Such cake/dispenser combinatins do not deliver a consistent amount of available chlorine over the life of the cake. Dirksing also discloses a dosing dispenser of the "bottom-feed" type illustrated in Figures 1-8 and 15-17. Symmetrical rectangular-shaped cakes are used therein. In such dispensers the bleach cake is only partially immersed in dosing liquid in the reservoir.

A second problem noted where the cake is completely immersed in water is that the pourable fluid capacity of the dispenser resevoir increases over the life cycle of the product. As a result of this, a dispenser which has been in use for some time contains a larger mass of hypochlorite solution, compared to the quantity contained in the reservoir during the early usage life of the dispenser when the cake itself occupies a larger portion of the reservoir volume.

Another problem with dissolving prior art calcium hypochlorite cakes in bottom-feed dispensers is excess swelling. Excess swelling of a cake can break the plastic dispenser case. Excess swelling can cause a cake to hang up and not gravity feed into the dispenser reservoir resulting in waste of chemicals. On the one hand, a swelling cake sized so small to avoid the hang up problem, results in an under utilization of dispenser space and a shorter life for the dispenser. On the other hand, if the dispenser is oversized to accommodate a larger cake size, the dispenser will be too bulky to fit in many toilet tanks.

A partially dissolving cake is disclosed in commonly owned U.S. Pat. No.4,281,421, Nyquist, Kitko and Stradling, issued August 4, 1981. The Nyquist et al. patent is directed to a partially insoluble metasilicate cake. It has been discovered that a drawback to the metasilicate cake in a bottom-feed dispenser is that much of the hypochlorite is wasted. All of the cake is not immersed in liquid and "leaching" will not dissolve the active located in the top part of the cake. Another drawback is nonuniform delivery of the active.

An object of the present invention is to provide a dispenser and cake combination which delivers all of the available chlorine in the cake at a substantially uniform rate, over a long period of time, throughout the life of the dispenser.

Other objects of the present invention will be apparent in the light of the following disclosure.

Summary of the invention The present invention comprises a passive dosing dispenser, having a reservoir with a compartment housing a calcium hypochlorite cake which is gradually depleted as doses of water are routed through the dispenser reservoir. Each dose of water contacts a lower portion of the cake, dissolving a portion of the hypochlorite to form a hypochlorite solution for release at a later time. The invention is characterized in a selection of the water-soluble calcium hypochlorite cake composition in combination with said dispenser.

The cake comprises a water-soluble calcium hypochlorite material and a selcted salt which controls the swelling of the calcium hypochlorite material. Preferred salts are selected from the group consisting of: lithium chloride, lithium hypochlorite, lithium sulfate, lithium sulfate hydrate, lithium hydroxide and equivalent calcium hypochlorite swelling control salts. The term "cake" as used therein means a calcium hypochlorite based cake, unless otherwise specified. The term "swelling control" as used herein means reducing the tendency of a cake to swell upon contact with water. The cake of this invention will swell less than one without said effective amount of said salt.The reservoir compartment housing the cake, and the cake are so sized so that free space between the corresponding cake surfaces and dispenser walls will allow the cake to swell some while allowing the cake to gradually dissolve and gravity feed into the dose volumes of water which are routed through the reservoir until the cake eventually disappears. The practice of this invention saves chemicals and increases the effective life of the dispenser as compared to dispensers which contain calcium hypochlorite cakes which do not dissolve completely due either to their compositions or to excessive swelling.

Brief description of the drawings While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed the present invention will be better understood from the following description in conjunction with the accompanying drawings in which: Figure 1 is a partially torn away perspective view of a bottom-feed passive dosing dispenser containing a solid cake.

Figure 2 is a simplified sectional view which shows a portion of a cycle of the dispenser shown in Figure 1 and which view is taken along section line 2-2 of Figure 1.

Figures 3, 4, 5 and 6 are perspective views of four different geometric forms of solid hypochlorite cakes.

Detailed description of the invention The dosing dispenser of this invention is typically placed into the water tank of a toilet. The dispenser has means for receiving a dose volume of water from the flush tank of the toilet. The received water is routed to a reservoir within the dispenser which contains the calcium hypochlorite cake. The dispenser has means for immersing a lowermost portion of the cake to a predetermined depth in the received water to facilitate dissolving a portion of the hypochlorite for dispensing at a later time. The cake is sized to initially occupy most of the cake compartment space within the dispenser reservoir. The cake and the cake compartment preferably have cake surfaces and vertical compartment walls which are parallel to each other.It is important that there is at least 0.4 cm to 4 cms of free space between the vertical cake surfaces and the cake compartment walls. Some preferred free spaces are from 0.4 cm to 4 cms, 0.5 cm to 1.5 cms, and 0.5 cm to 2 cms.

The dispenser retains the hypochlorite solution in substantial isolation from the body of toilet tank water during quiescent periods in between flushes. The dispenser also has means for releasing the hypochlorite solution from the dispenser into the tank water in the flush tank when the water drains from the tank into the toilet bowl during flushing. Available chlorine typically at a level of from about 2 parts per million (ppm) to about 10 ppm is provided in the toilet bowl water. The hypochlorite solution formed in the dispenser reservoir generally contains from about 0.5% to about 15% available chlorine. The solid cake composition of this invention is formulated to slowly dissolve and "gravity feed" into the water of the reservoir of the dispenser and disappear after the toilet has been flushed a sufficient number of times to exhaust all of the hypochlorite in the cake.

The selected calcium hypochlorite cake of this invention is a tableted solid composition comprising: (I) an effective amount of a water-soluble calcium hypochlorite cake swelling control salt selected from the group consisting of lithium hypochlorite material (Form 2 (g)), lithium hydroxide, lithium sulfate hydrate, lithium chloride and other water-soluble lithium salts, and mixtures thereof; and (II) from about 10% to about 98% of a substantially stable calcium hypochlorite material containing (i) from about 65% to about 78% calcium hypochlorite, and (ii) the balance being a mixture of salts and other by-product materials normal to the manufacture of calcium hypochlorite.

Cake preparation The compacted solid calcium hypochlorite cake compositions ofthis invention may be prepared by conventional compacting procedure. For example, granules of calcium hypochlorite, e.g. HTH Q, and granules of the selected swelling control salts are mixed together, and this mixture is then pressed into a cake with a compacting machine. The granules are generally in a size range of from about 50 microns to about 1,000 microns prior to compacting. The compacted solids can also be formed by tabletting, "slugging", Chilsonating, or otherwise converting the granular hypochlorite mixture into compacted forms.

The compacted solids can be formed, for example, in a conventinal tabletting machine. The granular calcium hypochlorite and granular swelling control salt are initially weighed and then dry mixed to produce a homogeneous mixture. This resulting mixture is then stamped into a tablet, i.e., a compact cake. Compacting may be accomplished at pressures of from about 0.5 tons/square inch to about 200 tons/square inch, preferably from about 1.0 tons/square inch to about 50 tons/square inch, and most preferably from about 1.5 tons/square inch to about 5.0 tons/square inch. The compacting can be done on any conventional compacting apparatus, e.g. a Stokes Model R4 Tablet Press. The compacted cakes generally have a specific gravity of about 1.3 to about 2.3, preferably from about 1.5 to about 2.0.

The cake is formed into shapes with dimensions appropriate to fit the cake compartment of the gravity feed dosing dispenser which holds the cake.

A preferred cake exhibits a geometric form that has nonuniform cross-sectional area, as measured along at least a portion of its vertical height, the area generally increasing with vertical height. Preferred cakes of this type exhibit rounded or wedged tapered bottoms (see Figures 3,4 and 6).

Method of use The dosing dispenser of th is invention is used as a disinfectant chlorine source in flush toilets. The compacted compositions are placed within a dispenser which is used within the flush tank of the toilet. An operable "gravity feed' dispenser is shown in Figures 1 and 2. The compacted cakes should be of a size to fill from about 50% to about 90% of the volume of the cake compartment surrounding the cake. Preferably about 50% to about 70%. Some unoccupied spaced is needed to allow for proper feeding of the cake upon contact with water. Sufficient cross-sectional space between the cake and the cake compartment walls is important to avoid "cake hang-up," which results in chemical waste.

A dose volume of toilet tank water is introduced into the dispenser during a normal water rise in the flush cycle of the toilet, contacting the cake composition in the dispenser. This water remains in the dispenser in contact with the lowerportion of the cake. About 0.5% to 20%, preferably 1 % to 5%, of the total surface area of the cake is initially exposed to the water within the dispenser. During the time between flushes a portion of the hypochlorite dissolves in the water, thereby forming a relatively concentrated solution of hypochlorite.

When the toilet is flushed, a dose of concentrated hypochlorite solution is discharged into the toilet bowl along with substantially all the water in the flush tank.

Cake swelling control is important in the context of a dissolving cake in a bottom-feed dispenser. The degree of swelling that can be tolerated depends on the size of the cake relative to the size of the dispenser cake compartment housing the cake which determines cake life and functionality.

Calcium Hypochlorite The calcium hypochlorite raw material for the purpose of the present invention is preferably a solid, dry calcium hypochlorite granular material containing at least about 65% by weight of calcium hypochiorite and about 5% of water, the balance being materials usually resulting from the process of manufacture, e.g., sodium chloride, calcium hydroxide, chloride and carbonate. In a reported practice of calcium hypochlorite manufacture, the calcium hypochlorite is obtained as a slurry containing crystals of calcium hypochlorite dihydrate [Ca(OCI)2.2H2O] in a mother liquor consisting essentially of an aqueous solution of calcium hypochlorite and sodium chloride.The slurry is filtered on a rotary vacuum filter to produce a "filter cake" that retains sufficient mother liquor to have a moisture content of 45% to 50% by weight. The filter cake, e.g., from an Eimco Filter, when dried directly yields the granular 70% calcium hypochlorite of commerce.

However, if a higher concentration of calcium hypochlorite is desired, the wet filter cake may be washed with water to remove some of the mother liquor and then filtered or centrifuged or otherwise processed to separate further quantities of liquid and to form a wet filter cake which, on drying, produces granules which contain from about 85% to about 90% by weight of calcium hypochlorite.

The calcium hypochlorite content of the calcium hypochlorite granules used in formulating compositions of this invention is generally at least about 60% and preferably ranges from about 65% to about 75% by weight. The compound calcium hypochlorite contains about 100% available chlorine, thus a composition containing 65% calcium hypochlorite contains about 65% available chlorine. Commercial calcium hypochlorite usually contains at least about 65% available chlorine and, as manufactured, contains 71% to 73% of calcium hypochlorite and about 5% water. A commercial calcium hypochlorite containing about 65% to about 72% available chlorine is marketed underthe name "HTH" by Olin Mathieson Chemical Corporation.Atypical analysis of HTH Q is as follows: Typical Ingredient Weight % Calcium hypochlorite 70 -75 Ca(OC1)2 Sodium chloride 4 - 23 NaCI Calcium hydroxide 1.5- 5 Ca(OH)2 Calcium carbonate 1.0- 5 CaC03 Calcium chlorate 0.4- 4 Ca(C103)2 Calcium chloride 0.5- 3 CaCI2 Water 0.4- 8.5 Processes for preparing calcium hypochlorite material may be found in U.S. Pat. No.3,953,354, Faust, issued April 27, 1976; U.S. Pats. Nos. 3,639,284, Long et al., issued February 1, 1972; and 3,560,396, Robson, issued February 2, 1971. Various calcium hypochlorite compositions contain varying amounts of Ca(OC1)2 as indicated herein.

Swelling control salts The solid cake compositions of this invention contain an effective amount of a swelling control salt.

"Swelling control salts" means water-soluble salts other than calcium hypochlorite which are compatibly incorporated into calcium hypochlorite compositions and provide reduced swelling for the cake compared to cakes made of essentially commercial grade calcium hypochlorite material, such as HTH. Swelling control salts are commercially available. They are selected inorganic salts which are not reactive to calcium hypochlorite and provide reduced swelling control of calcium hypochlorite material. Examples of preferred swelling control salts include lithium hypochlorite, lithium hydroxide, lithium sulfate, lithium sulfate hydrate, lithium chloride, and mixtures thereof.

An effective amount of swelling control salt in a typical calcium hypochlorite cake composition can range from about 1% to about 90% by weight of the cake, preferably a cake composition contains from about 2.5% to about 40% of added swelling control salt.

The choice of swelling control salts will affect the hydration and swelling of the compacted cake on its initial exposure to the aqueous environment within the dispenser. To minimize cake swelling and improve dissolution of the disinfecting composition, preferred calcium hypochlorite cake compositions include "Form 2" and sodium chloride. Lithium hypochlorite, LiOCI, a preferred swelling control salt is preferably obtained in its commercially available form referred to herein as "Form 2", which contains from about 25% to about 35% of pure lithium hypochlorite with the balance being inorganic diluents and moisture. The pure compound lithium hypochlorite contains about 120% available chlorine, thus a composition containing 10% lithium hypochlorite receives about a 12% available chlorine contribution from the lithium hypochlorite component. A commercial granular lithium hypochlorite, marked with U.S. Pat. No.3,171,184, contains about 36% available chlorine and is marketed underthetrade name "Form 2" by the Lithium Corporation of America. Atypical analysis of "Form 2", as reported by the manufacturer, is as follows:: ELEMENTAL ANALYSIS Weight % Ingredient Typical Maximum Minimum Available chlorine 36 38 35 Lithium hypochlorite 30 31 29 Lithium 4.5 5.3 3.5 Sodium 18 22 14 Potassium 3 6 2 Chlorides (total) 45 55 34 Sulfates 11 22 5 Chlorates 2 4 1 Carbonates 1.5 3 0.5 Chlorites 0.1 0.5 0.05 Hydroxides 0.5 1 0.2 Water 7 9 4 TRACE METALS Metal Typical Maximum Iron 7 ppm 20 ppm Copper 1 ppm 2 ppm Nickel 0.1 ppm 0.5 ppm Mercury 0.05 ppm 0.1 ppm Lead 0.5 ppm 1 ppm Arsenic 0.1 ppm 0.5 ppm Zinc 1.5 ppm 3.0 ppm CHEMICAL ANALYSIS Weight % Ingredient Typical Guaranteed Available chlorine 36 35 LiOCI (active ingredient) 30 NaCI 34 Na2SO4 and K2SO4 20 LiCI 3 Lilo3 3 LiOH 1 Li2CO3 2 H20 PHYSICAL PROPERTIES: Bulk Density: Loose, 58 Ibs/cu.ft.

Packed, 65 lbs/cu.ft.

Particle Size, U.S. Standard Sieves: Standard, -10+70 Special, -10+20, -20+50 Processes for preparing lithium hypochlorite compositions are found in U.S. Pats. Nos. 2,590,794, Robson, issued March 25,1952; 2,534,781, MachMahon, issued December 19,1950; and 3,171,814, Orazem petal., issued March 2, 1965. The term "lithium hypochlorite" used in the specification and claims includes commercially available lithium hypochlorite material, such as Form 2. Various lithium hypochlorite compositions contain varying amounts of LiOCI, as indicated herein.

The preferred cake of this invention comprises "HTH" calcium hypochlorite and "FORM 2" at a weight ratio of from 3:2 to 19:1, and most preferably 3:2 to 9:1. Another preferred cake comprises "HTH" and lithium sulfate hvdrate at a weight ratio of from 1:9 to 49:1, most preferably 19:1. Cake compositions of this invention can comprise "HTH" and lithium hydroxide at a ratio of 4:1 to 19:1, preferably 9:1. Sodium chloride can be present in the cakes at levels up to 50%.

Selection of swelling control salts The following salts exhibit cake swelling control: Form 2 is most preferred due to its available chlorine content and exceilent swelling control properties; also preferred are lithium sulfate hydrate; lithium hydroxide; and lithium chloride.

Table I shows a list of ranges of HTH/salt ratios that exhibit swelling control.

TABLE I Mostpre- Less pre ferred % Confi ferred % Confi Salt HTHlSalt dence* HTHlSalt dence* Form 2 90:10 to 60:40 99 or more 95:5 to 90:10 90 Li2SO4 H2O 95:5to 10:90 97.5 or more 98:2 to 95:5 95 LiOH 90:10to80:20 99 or more 95:5to90:10 90 *This tells how confident one can be judging from statistical test, i.e., that the ratio of HTH/sait combination is effective in swelling control.

AW + AT Amount of swelling = 2 where AW = change in width due to swelling AT = change in thickness due to swelling Cake swelling test procedure The following cake swelling test procedure was used to collect the data reported in Tables II through IV.

1. The cake ingredients, 100 gms, were weighed in glass jars and capped to keep out moisture.

2. The contents of the glass jars were poured into 77 mm x 42 mm die boxes and stamped using a Stokes Model R4 Tablet Press. The length and width of the cakes were about 77 mm x 42 mm but the cake thicknesses varied from about 17 mm to 21 mm due to the differences in the specific ingredients used.

3. The cakes were then reweighed to assure that each contained about 100 gms of ingredients and the width and thickness of each cake was measured in millimeters using a caliper and recorded.

4. Each cake was then placed into a 250 ml beaker. The cake was propped up at an angle of about 80" with a plastic hanger (The hanger is generally described in U.S. Pat. No.4,247,070, Dirksing, January 27, 1981. The hanger was not used for the purpose described in that patent, but was modified for this test.

The hanger was placed upside-down and the stem cut to the height of the beaker).

5. Then, about 50 mls of distilled water were poured into each beaker containing the cake and a watch glass placed thereover.

6. At the end of 10 days each cake was removed from its beaker and its width and thickness remeasured, just above the waterline, using a caliper, in millimeters.

7. The difference between the sum of a cake's width and thickness initial measurement (3) and the final measurement (6) represents the amount of cake swelling in millimeters.

The data in Table II show the amount of swelling for various HTH/salt cakes at a ratio of 90:10 (screening test). The amount of swelling is the difference between the sums of a cake's width and thickness, measured in millimeters, before and after contact with water according to the Cake Swelling Test Procedure described herein. The salts shown below the line do not exhibit swelling control at the 90/10 level tested.

TABLE II Amount of Swelling*** Number of Salt Mean (mm) SD* (mm) OLservadons LiOH 1.86 .76 7 LiCI 3.37 .81 4 MgSO4** 4.05 .91 3 Form 2 4.99 1.73 9 Li2SO4 5.17 2.21 6 Li2CO3 6.91 2.35 4 Na2SO4 7.47 3.93 4 CaCI2 7.96 2.88 4 Ca3(PO4)2 8.54 .62 2 Ca(OH)2 8.74 1.50 5 K2SO4 9.22 1.79 4 Na2CO3 9.24 3.17 4 Li3PO4 9.76 2.29 4 Na3PO4 10.03 2.85 4 K2CO3 10.25 3.94 3 Mg(OH)2 10.48 1.67 5 CaCO3 10.54 1.82 4 KCI 10.67 3.51 4 CaSO4 11.04 1.40 5 NaCl 11.48 2.30 4 K3PO4 12.16 3.15 4 HTH 7.69 2.49 12 * Standard deviation ** Cakes made with MgS04 were too soft for preferred compositions of this invention.

***Tested at 80 F/80%RH and 80 F and 400F/ambient humidity atmosphere surrounding the test beakers.

Table IIA reflects the percent of confidence.

TABLE IIA Degrees of Salt tcaic t95* this t99 tgg g5 Freedom LiOH 7.53 1.74 2.11 2.57 3.97 17 LiCL 5.24 1.76 2.15 2.62 4.14 14 MgSO4 4.09 1.77 2.16 2.65 4.22 13 Form 2 2.93 1.73 2.09 2.54 3.88 19 Li2SO4 2.18 1.75 2.12 2.58 4.02 16 Li2CO3 .57 1.76 2.15 2.62 4.14 14 *The value oft at 95% confidence; the subscripts show the amount of confidence.

The data shown in Table Ill and Table IIIA reflect the amount of swelling for various HTH/Form 2 ratios and the degree of confidence. Swelling is the difference between the sums of a cake's width and thickness, measured in millimeters, before and after contact with water according to the Cake Swelling Test Procedure as described herein.

TABLE III Amount of swelling** Number HTH/Form 2 Mean (mm) SD* (mm) Observations 100/0 7.69 2.49 12 99.9/.1 8.21 2.12 2 99/1 7.71 .33 2 98/2 9.29 1.30 3 95/5 6.07 1.26 4 90/10 4.99 1.73 9 85/15 4.25 1 80/20 2.93 1.08 6 70/30 2.99 .77 4 60/40 3.06 .92 3 50/50 8.07 3.45 3 40/60 10.0 1 30/70 17.68 2.25 3 10/90 21.08 4.27 3 5/95 24.0 1 0/100 13.32 4.43 6 *Standard deviation **80 F/ambient humidity atmosphere surrounding the test beaker TABLE IIIA HTHIF2 95/5 90/10 80/20 70/30 60/40 tcaic 1.69 2.93 5.64 5.76 5.18 t90 1.35 1.33 1.34 1.35 1.35 t95 1.76 1.73 1.75 1.76 1.77 t97.s 2.15 2.09 2.12 2.15 2.16 t88 2.62 2.54 2.58 2.62 2.65 t99.95 4.14 3.88 4.02 4.14 4.22 Degrees of 14 19 16 14 13 freedom The data shown in Table IV reflect the amount of swelling control for various ratios of HTH/LiOH and HTH/Li2S04.H2O.

TABLE IV Amount of swelling** Mean HTH/Salt Mean SD* Number of Salt HTH/Salt fmm) Observations LiOH 99.9/.1 8.13 1.12 2 99/1 8.26 .24 2 98/2 7.26 2.06 2 95/5 4.58 2.91 2 90/10 1.86 .76 7 80/20 5.30 1.91 3 70/30 6.81 .15 2 60/40 6.52 .13 2 50/50 6.22 2.33 2 Li2SO4.H2O 99.9A1 7.48 1.86 2 99/1 7.04 1.44 2 98/2 6.14 .35 2 95/5 2.83 .98 2 90/10 5.17 2.21 6 80/20 2.40 .12 2 70/30 1.99 .25 2 60/40 1.93 .29 2 50/50 1.91 .33 2 30/70 1.55 .26 2 10/90 1.24 .30 2 * Standard deviation ** 80 F/ambient humidity atmosphere surrounding the test beaker The data shown in Table IVA reflect the t value with the largest amount of confidence possible less than tcalcg TABLE IVA Degrees of Ratio tcaic too t95 t97.5 t99 f99.95 Freedom Salt: LiOH 98/2 .26 1.36 12 95/5 1.43 1.36* 1.78 12 90/10 7.53 1.33 1.74 2.11 2.57 3.97* 17 80/20 4.14 1.35 1.77 2.16 2.65* 4.22 13 70/30 1.21 1.36 12 60/40 .61 1.36 12 50/50 .82 1.36 12 Salt: Li2SO4.H2O 99.9/.1 .14 1.36 12 99/1 .52 1.36 12 98/2 2.04 1.36 1.78* 2.18 12 95/5 4.87 1.36 1.78 2.18 2.68 4.32* 12 90/10 2.18 1.34 1.75 2.12* 2.58 16 80/20 7.31 1.36 1.78 2.18 2.68 4.32* 12 70/30 7.70 1.36 1.78 2.18 2.68 4.32* 12 60/40 7.71 1.36 1.78 2.18 2.68 4.32* 12 50/50 7.65 1.36 1.78 2.18 2.68 4.32* 12 30/70 8.28 1.36 1.78 2.18 2.68 4.32* 12 10/90 8.61 1.36 1.78 2.18 2.68 4.32* 12 *The t value with the largest amount of confidece possible less than talc.

The data of Table V show that cakes "A" and "B" made of 100% HTH or 87/11% HTH/NaCI swell and hung-up, respectively, after 6 and 21 days, while the "C" cakes made of HTH/Form 2 did not hang-up in the product compartment of the dispenser.

TABLE V Comulative Grams Av. Cl2 (Amount of Av, Cl2 dispensed since day 0) A B C 87% HTH* 100% HTH** 90% HTH*** 11% NaCI 10% Form 2* Cum. Cum. Cum.

Grams Cl2 Grams Cl2 Grams Cl2 Cl2 Dis- Cl2 Dis- Cl2 Dis Days Left pensed Left pensed Left pensed 0 51.4 - =51 - =63.4 1 47.6 3.8 44.8 6.2 60.6 2.8 6 38.0 13.4 44.0 7.0 49.4 14.0 14 38.7 12.7 - - 40.9 22.5 21 35.9 15.5 - - 35.8 27.6 28 - - - - 33.6 29.8 Tablet Dimensions: A: *weight =83 grams; length (height) =7.62cm; width =4.06cm; thickness =1.52cm B: **weight =77 grams; length (height) =7.62cm; width =4.06cm; thickness =1.52cm C: ***weight =100 grams; length (height) =7.62 cm; width =4.06cm; thickness =1.78cm Dispenser/Cake Compartment Dimensions: height =8/13cm; width =5.08cm; thickness =2.18cm The first two types of cakes, A and B, shown in Table V, after 6 days of usage, were visually seen as excessively swollen and hanging up in the compartment. Thus, the 87% HTH/11 % NaCI (A) and the 100% HTH (B) type cakes stopped dispensing significant levels of Av. Cl2 after about 6 days because the cakes stopped gravity feeding in the dispenser.The "C" cakes, although initially thicker, continued to gravity feed because of controlled swelling.

Referring to Table VA, rectangular square cakes containing ratios of HTH Q to Form 2 Q from 95/5 to 50/50 plus added NaCI at levels of from 0% to 50% were tested for swelling control. The cakes were of the type shown in Figure 5 having an overall height of about 76 mm, a thickness of 18.8 mm and a width of 43 mm.

Each cake was placed in 250 ml beakers each containing 50 ml of ambient water. The water level on the cake was initially about 2 cm, which simulates the condition of a cake in use in a "bottom-feed" dispenser. The amount of swelling (mm) after a week for each cake is shown in Table VA. The data show that, in general, the addition of NaCI to HTH/Fo rm 2 compositions improves cake swelling control. In Table VA the amount of swelling (mm) is obtained by subtracting the sum of the initial cake width and thickness from the sum of the final cake width and thickness.

TABLE VA Amount of HTHIF2 Nail added to HTHIF2 mixture Ratio 0% /0% 50%** 95/5 4.5 mm 4.0 mm 90/10 4.5 mm 2.5 mm 3.0 mm 70/30 3.0 mm 2.5 mm 2.0 mm 50/50 8.0 mm 3.5 mm 2.0 mm Swelling = Final (width + thickness) minus Initial (width + thickness).

Referring now to Figures 1 and 2 in which identical features are identically designated, Figure 1 shows a preferred bottom-feed dispenser 20. The dispenser 20 contains a solid state calcium hypochlorite cake 21.

Dispenser 20 comprises a front wall 22, a back wall 23, sidewall segments 25,26,31,50,51 and 90, a top wall 28, bottom wall segments 29,53 and 54, and interior partitions 32, 55,56,57, 58,95 and 96, and cake support members 33. The cake support members 33 are of lesser thickness than the dispenser width to ensure that liquid can wash across part of the tapered lowermost surfaces 21 a and 21 b of cake 21 along its entire length.

The walls and partitions are rigid and define a liquid solution reservoir 65 for a liquid solution, a cake compartment 69, a siphon tube 44 having a second air trap 81 disposed adjacent thereof and having discharge reservoir 85, uppermost vertical passageway 86, a horizontal passageway 87, a vertical passageway 88 connecting with inlet/discharge conduit 80, said inlet/discharge conduit having a first air trap 81 disposed adjacent thereto, and vent means for the reservoir comprising passageways 71 and 72 and air vent 83.The lowermost edge of partition segment 58 is designated 59, the lowermost edge of partition segment 96 is designated 67, the exposed edge of bottom wall segment 29 is designated 61, the lowermost edge of level control partition 32 is designated 62, the uppermost edge of sidewall segment 31 is designated 93, and the lowermost edge of sidewall segment 26, which in conjunction with front and back walls 22 and 23, respectively, and sidewall segment 31 define air vent 83, is designated 64. The inlet/discharge port of dispenser 20 located at the lowermost end of siphon tube 44 is designated 78. The free spaces 68R and'68S around the cake 21 witin cake compartment 69 is designed to accommodate some cake swelling upon initial contact with water 63.If the free space is too small, the cake 21 will hang up on front wall 22, back wall 23, left side wall 25 and level control partition wall 32, and the chemicals will be wasted.

Referring to Figure 1, it is important that the total of the free space 68R between vertical rear and front cake surfaces 21 R and front and rear walls 22 and 23, respectively, be at least from 0.4 cm to 2 cms, preferably, from 0.5 cm to 1.5 cm, about half in front and half in rear. It is also important that the total of the free space 68S between vertical side cake surfaces 21S and sidewall 25 and level control partition wall 32 be at least from 0.4 cm to 4 cms, preferably from 0.5 cm to 2 cms. Free spaces 68R and 68S are needed for controlled cake swelling. Insufficient free space will result in the cake 21 hanging up on the vertical walls of the dispenser reservoir. Also, a minimum amount of free space 68T is needed between top cake surface 21T and top wall 28 for controlled cake swelling.Space 68T is preferably at least from 0.1 cm to 1 cm, and more preferably at least from 0.1 cm.

Referring to Table V, it will be noted that the free space for each of the cakes A and B corresponding to 68R, i.e., the total free space between vertical rear and front walls and the corresponding vertical surfaces of each cake was about 0.66 cm. The corresponding free space for cake C of the present invention was only 0.40 cm.

Although less free space was allowed for cake C, it did not "hang up" in the cake compartment.

The free spaces corresponding to 68S and 68Twere the same for the Table IV cakes A, B and C, 2.04 cms ad 0.51 cm, respectively.

The depth of immersion, i.e., water exposed cake surface area of cake 21 is controlled by the vertical distance "H" between the uppermost surface of product support members 33 and lowermost edge 62 of level control partition 32. The amount of interface between the cake and the liquid contained within the dispenser 20 controls the solid hypochlorite cake 21 dissolution rate. With dispenser embodiments of the type generally shown in Figure 1 it has generally been found that the vertical distance "H" should be less than about 1 cm, and most preferably less than about 0.5 cm.

A particularly preferred dispenser embodiment of the present invention (not shown) employs two shelf-like support members 33 such as present in Figure 1 secured to and projecting from back wall 23. A larger reservoir based on reservoir 65 can be made to be centrally positioned under two support members 33 to collect insoluble particles. A vertical distance "H" of about 10 mm between the uppermost surface of the support members and the lowermost edge of the level control partition can be employed.

The solid product in question initially can weigh about 60 grams and have a lowermost surface measuring 5 cm in length by about 1.27 cm in width.

Referring to Figure 2, when the dispenser 20 containing a calcium hypochlorite cake 21 is disposed, for instance, in a toilet tank (not shown) on a bracket or other mounting means (not shown) so that the FULL level of water 63 in the toilet tank is sufficiently high to at lest reach edge 64 of sidewall segment 26, the dispenser will respond as the level of water drops from the FULL position in the toilet tank when the toilet is flushed and thereafter as the level of water in the toilet tank rises to the FULL position after completion of the flush cycle. The flush cycle is fully shown and explained in said U.S. Pat. No. 4,208,747.

Referring to Figure 2 it is apparent that reservoir 65 will retain a portion of the concentrated hypochlorite product solution 103 after the dispensing operation is completed. The hypochlorite solution 103 thus retained will be available to cover rapid multiple flushes of the toilet and preferably is larger than shown, and/or a secondary reservoir (not shown) can be designed in bottom wall 29. Secondary solution reservoirs (not shown) can be designed to collect insoluble cake by-products (e.g., CaCO3) of hypochlorite solution 103 in the lowermost portions of primary solution reservoir 65.

When the level of the toilet tank water 63 is in the FULL position, as illustrated in Figure 2, the dispenser 20 will likewise be restored to the condition illustrated in Figure 2 and will remain in that condition during the ensuing quiescent period awaiting the next flush cycle of the toilet.

The dispenser embodiment 20 illustrated in Figures 1 and 2 can discharge a predetermined quantity or dose-volume of hypochlorite product solution 103 from the dispenser each time the toilet is flushed. The dose-volume of solution is substantially equal to the quantity of solution contained within dispenser 20 between lowermost edge 62 of level control partition 32 and lowermost edge 67 of partition segment 96 in addition to the column of product solution contained within passageway 71.The amount of hypochlorite product solution 103 that can be dispensed during each flush cycle is more easily understood by comparing Figure 2, which illustrates the condition of the dispenser 20 when the toilet tank water level 75 is FULL and air vent 83 has been blocked by the water, with Figure 1, which illustrates the condition of an empty dispenser when the solution level within solution reservoir 65 would be at lowermost edge 67 of partition segment 96 and the dose-volume of solution has been released through inlet/outlet port 78.

The solid, water-soluble calcium hypochlorite cake 21 contained in cake compartment 69 will dissolve in the water introduced during each flush cycle to form the hypochlorite product solution 103 until such time as the solution becomes saturated or the toilet is again flushed. As the lower portions of the cake 21 are consumed by exposure to the liquid, the solid product will feed towards support members 33 and wall 29 within cake compartment 69.Because the volume and exposed surface area of cake 21 below edge 62 of level control partition wall 32 remain essentially constant throughout the life of the cake, the strength or concentration of the hypochlorite solution 103 is particularly controlled throughout the life of the dispenser 20, assuming an adequately long quiescent period for the solution to reach a normal concentration level is provided intermediate te flush cycles, i.e., about 4 hours between flushes. It should be obvious that a shorter quiescent period will result in a hypochlorite solution 103 that will be correspondingly less concentrated with less dissolved cake 21.

While the exemplary embodiment of dispenser 20, may be constructed by adhesively securing sections of relatively rigid Plexiglas (Registered Trademark of Rohm and Haas Company) to one another, other relatively rigid materials which are substantially inert with respect to the intended product and aqueous solutions thereof can be used to construct the dispensers. Furthermore, the dispensers may be constructed or formed at high speed and relatively low cost utilizing various manufacturing techniques well known in the art. For example, the dispensers could be vacuum thermoformed in two sections of a material such as polyvinyl chloride having an initial thickness of about 0.5 mm to 1 mm, the solid, water-soluble product inserted therebetween and the two sections thereafter secured to one another as by heat sealing, adhesives, etc.

The dispenser 20 in Figure 1 is shown prior to the charging operation, i.e., before it is immersed in toilet tank water 63 as shown in Figure 2. In a flush cycle (not shown) the toilet tank water 63 rises, it enters siphon tube 44 and discharge reservoir 85 through inlet/discharge port 78. Air within the upper reaches of the siphon tube 44 is allowed to vent through discharge reservoir 85, vertical passageway 88, inlet/discharge conduit 80, liquid solution reservoir 65, vent passageways 71 and 72 and air vent 83. As the level of the toilet tank water 63 continues to rise, it begins to enter horizontal passageway 87.Because the difference in elevation of the water in the toilet tank and the water within the siphon tube is relatively small prior to air vent 83 becoming blocked, the water head or water pressure available to force the water in siphon tube 44 around the loop through vertical passageway 88 and into inlet/discharge conduit 80 is likewise quite small.

To minimize the required driving force to initiate water flow through the loop, the dispenser 20 preferably employs a series of passageways 86,87 and 88, each of which is smaller in cross-section than any portion of the one immediately preceding it, thereby providing capillary suction in the direction of flow which tends to draw the water from the siphon tube 44 into the inlet/discharge conduit 80. It is of course recognized that a maximum degree of capillary suction may be provided by employing passageways 86,87 and 88 which are tapered and exhibit a continued reduction in cross-section in the direction of liquid flow during the dispenser charging operation. If desired, the entire length of the siphon tube 44 above the discharge reservoir 85 may be convergent in the direction of water flow during the charging operation.

Once toilet tank water 63 enters inlet/discharge conduit 80 and begins to collect in the solution reservoir 65, air is trapped in air trap 81 disposed adjacent inlet/discharge conduit 80 (not shown). Namely, an air bubble is retained within the confines of the air trap 81 defined by partition segments 55,56,57 and 58, which condition persists as long as toilet tank water 63 continues to enter the dispenser 20.

Referring again to Figure 2, when the level 101 of incoming liquid within cake compartment 69 reaches lowermost edge 62 of level control partition 32, an air-lock is formed in the uppermost reaches of the cake chamber 69, thereby preventing the liquid from rising further within the cake compartment 69. It should be noted that the liquid contacts only a lower surface area of solid product 21 up to a predetermined cake height "H" up to lowermost edge 62.

In the event the FULL level of the toilet tank is below the air vent 83, the level 102 of hypochlorite product solution 103 in passageway 71 will be identical to the level 75 of the toilet tank water 63 surrounding the dispenser, while the level 101 of product solution 103 within cake compartment 69 will be controlled by lowermost edge 62 of level control partition 32.

In the event level control partition 32 is eliminated and the FULL level of the toilet tank is below the air vent 83, the level of product solution 103 within the dispenser 20 will be identical to the level 75 of toilet tank water 63 surrounding the dispenser 20. In all cases, dispenser 20 will function to isolate the resultant hypochlorite solution 103 contained in the upper reaches of cake compartment 69 from the surrounding toilet tank water 63, whether or not air vent 83 is blocked by toilet tank water. In the event air vent 83 is blocked by toilet tank water, isolation is provided by means of an air-lock created in the upper reaches of passageway 72 in conjunction with the air-lock created in horizontal passageway 87. In the event air vent 83 is not blocked by toilet tank water, the vent to atmosphere provides the desired isolation from the toilet tank water 63.

Referring again to Figure 2, which represents the condition of the dispenser 20 when the toilet tank water level 75 is in its FULL position, the bulk of the air bubble retained within air trap 81 during the charging operation has rotated about edge 59 of partition segment 58 so as to substantially fill horizontal passageway 87 as well as the uppermost portions of vertical passageways 86 and 88, thereby isolating the resultant liquid hypochlorite product solution 103 contained within the inlet/discharge conduit 80 from the toilet tank water 63 contained within passageway 86 of siphon tube 44.The resultant hypochlorite product solution 103 contained within passageway 71, cake compartment 69, solution reservoir 65 and inlet/discharge conduit 80 is completely isolated from toilet tank water by means of the air-lock provided in the uppermost sections of passageways 71 and 72 and the air-lock provided in the uppermost sections of vertical passageways 86 and 88 and horizontal passageway 87.

As will be appreciated by those skilled in the art, the toilet tank water 63 brought into contact with cake 21 during the charging operation will continue to dissolve cake 21 at least until such time as the hypochlorite product solution 103 becomes saturated or until such time as the toilet is flushed and a predetermined quantity or dose-volume of the liquid hypochlorite product solution 103 is available for dispensing and is either completely or partially discharged. As will also be appreciated by those skilled in the art, the exterior surfaces of cake 21 are preferably so configured as to permit a uniform delivery of hypochlorite solution 103 over the life of the calcium hypochlorite cake product 21. To this end, the exterior surfaces of the solid cake product 21 is preferably tapered at the bottom to offset the effect of relatively high initial solubility of a fresh cake.Cake 21 and the cakes of Figures 3,4 and 6 all show preferred tapered cakes. Figures 3 and 4 show the more preferred cakes.

Transfer of hypochlorite product solution 103 from the solution reservoir 65 into the discharge reservoir 85 to be discharged through the inlet/discharge port 78 continues until such time as the solution level in solution reservoir 65 reaches edge 67 of partition segment 96 (not shown), thereby venting siphon tube 44 and allowing the product solution 103 contained therein to be released into the toilettankwater 63.

The discharge reservoir 85 preferably comprises an enlarged end of the siphon tube 44. The discharge reservoir 85 and its associated inlet/discharge port or ports 78 can be sized to provide for discharging of the hypochlorite solution 103 at almost any point in the flush cycle and at almost any rate of discharge.

The solid calcium hypochlorite cakes of this invention do not form gels, but do form a small amount of insoluble by-products, e.g., calcium carbonate. So, dispensers having support members 33 are preferred to ensure that insoluble particles are washed away. The support members 33 positioned in the lowermost portion of cake compartment 69 support cake 21 and are a level control means to control the liquid level in contact with the cake 21. Said support members 33 also help to prevent insoluble particles from building up on and around the hypochlorite cake. The support members 33 also serve to control the area of contact between the liquid contained within the dispenser reservoir and cake 21.

So long as liquid is routed through the product chamber during each flush cycle of the toilet, the cake insoluble by-products will continue to be dispersed into the liquid solution and which ultimately settles into the solution reservoir 65 located generally beneath the cake compartment 69. Accordingly, the tendency of the insoluble cake by-products to build up on and around the cake is minimized.

With particularly preferred dispenser embodiments of the present invention, the discharge of the bulk of the liquid hypochlorite product solution generally occurs just before the completion of the flush cycle before the toilet tank discharge outlet is closed and before tank refill begins.

The dispenser disclosed herein is particularly well suited for use with other component products particularly if they are isolated from each other prior to use. Each dispenser section of such a plural product dispenser will also maintain such a product component in isolation from the toilet tank water and simultaneously dispense the products when the toilet is flushed. Such plural product dispensing embodiments could be fabricated as a single unit suspended in the toilet tank independently of one another, or interdependently suspended in the toilet tank by means of a common bracket or the like.Because the constant volume of solution dispensed during each flush cycle may readily be determined, it is thus possible to size such plural product dispensers so that each of the product components will be completely consumed at about the same point in time, thereby minimizing waste of any particular component.

Referring now to Figure 3, solid cake 221 illustrates a preferred hypochlorite bleach cake which exhibits symmetrical side tapers 221 a and 221 b. Cake 221 has a total height of 3 inches (7.62 mm) a taper height of 1.2 inches (30.5 mm), a top width of about 1.55 inches (39.4 mm), a bottom width of about 3.8 mm and the taper forms an angle of about 60 from the horizontal. The tapers 221 a and 221 b preferably form angles of from about 30 to about 65 from the horizontal, but is functional over a wider range. Cake thickness 223 is preferably 12 mm to 20 mm; cake width 224 is preferably 35 mm to 50 mm and the cake overall height 225 is preferably abot 70 mm to 85 mm.The cake taper height 226 of tapers 221a and 221 b is preferably about 25% to about 50% of the total cake height 225, but is functional over a wider range.

Referring now to Figure 4, another preferred cake 321 shows a rounded bottom taper 322. This preferred cake 321 has thickness, height and width geometry which is generally the same as that of cake 221, except for the geometry of the taper 322. The rounded bottom taper 322 has an arc length 332a of about 30 mm. In preferred cakes of similar geometry, the arc of the rounded bottom may vary from about 20 mm to about 50 mm.

Figure 5 is a rectangular prism-shaped cake 421 with a square bottom.

Figure 6 is a perspective view of a tapered cake 521 with one tper 522.

While particular embodiments of the present invention have been illustrated and described, it will be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention and it is intended to cover, in the appended claims, all such modifications that are within the scope of this invention.

Claims (14)

1. An article of manufacture comprising: A. a dosing dispenser, and B. A calcium hypochlorite cake, said dosing dispenser comprising a reservoir having a cake compartment, means for allowing a dose volume of water to be routed through said reservoir with each dispensing cycle and means for immersing a lowermost portion of said cake to a predetermined depth in said water to facilitate dissolving a portion of said hypochlorite cake for dispensing at a later time, Characterized in that: Said cake is substantially completely watersoluble and comprises: I. an effective amount of a water-soluble lithium salt selected from the group consisting of:lithium hypochlorite material, lithium hydroxide, lithium sulfate, lithium sulfate hydrate, and lithium chloride, and mixtures thereof; and II. from about 10% to about 98% of a substantially stable calcium hypochlorite material containing (i) from about 65% to about 78% calcium hypochlorite and (ii) a mixture of salts and other by-product materials normal to the manufacture of calcium hypochlorite; and wherein said cake is formulated such that swelling of said cake upon contact with said water is less than the swelling of a cake consisting essentially of said calcium hypochlorite material, said reservoir having vertical walls, said cake having vertical surfaces, said walls and corresponding cake surfaces having free space between them of at least 0.4 cm to 4 cm, and wherein said cake gradually dissolves and gravity feeds into said water with each cycle until the cake disappears.

2. The invention of Claim 1 wherein said cake is a composition comprising said calcium hypochlorite material, and said lithium hypochlorite material at a weight ratio of 3:2 to 19:1.

3. The invention of Claim 2 wherein said ratio is 3:2 to 9:1.

4. The invention of Claim 3 wherein said ratio is 9:1.

5. The invention of Claim 1 wherein said cake is a composition comprising said calcium hypochlorite material, and said lithium sulfate hydrate at a weight ratio of 1:9 to 49:1.

6. The invention of Claim5 wherein said ratio is 1 :9to 19:1.

7. The invention of Claim 1 wherein said cake is a composition comprising said calcium hypochlorite material and said lithium hydroxide at a weight ratio of 4:1 to 19:1.

8. The invention of Claim 7 wherein said ratio of 4:1 to 9:1.

9. The invention of Claims 1,2,3, 4, 5, 6,7 or 8, wherein said cake is a composition comprising sodium chloride at a weight percentage of 1% to 50%.

10. The invention of Claims 1,2,3,4,5,6,7 or 8, wherein said cake comprising sodium chloride at a weight percent of from about 5% to about 20%.

11. The invention of Claims 1,2,3,4 or 5, wherein said calcium hypochlorite material is a composition comprising the following components, expressed in percentages by weight:

60.0 - 75.0 calcium hypochlorite 0.5- 3.0 calcium chloride 0.4- 4.0 calcium chlorate

1.5- 5.0 calcium hydroxide

1.0 - 5.0 calcium carbonate

4.0 - 23.0 sodium chloride 0.4- 8.5 water

12. The invention of Claims 1, 2,3,4 or 5, wherein said calcium hypochlorite material is a composition comprising the following components, expressed in percentages by weight: 65 - 75 calcium hypochlorite

1.4 calcium chloride 0.9 calcium chlorate

2.1 calcium hydroxide

1.3 calcium carbonate

21.3 sodium chloride 4- 6 water 13. The invention of Claims 1,2,3,4 or 5, wherein said lithium hypochlorite material contains the following components, expressed in percentages of weight: 25-35 lithium hypochlorite 34 sodium chloride 20 sodium sulfate and potassium sulfate 3 lithium chloride 1 lithium hydroxide 2 lithium carbonate 7 water

14. The invention of Claim 1 wherein said free space is from 0.5 cm to 2 cm.