TECHNICAL FIELD

The present invention relates to a lavatory cleansing block and a method of manufacturing a lavatory cleansing block. More specifically, the invention is also concerned with lavatory cleansing blocks that are particularly suitable for intermittent contact with the flush water of a lavatory or urinal.

BACKGROUND

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.

Lavatory cleansing blocks are currently known in the market. These cleansing blocks are typically provided to be brought into contact with water (during flushing) to release active constituents for cleaning the lavatory or urinal. These cleansing blocks are utilised by immersing the block in the water cistern of a lavatory or urinal, either as a free-standing block or by placing the block in a dispensing device positioned in a lavatory bowl.

Lavatory cleansing blocks are typically provided for performing a cleansing function and for optionally addressing the issue with the buildup of microorganism in the lavatory or urinal. In order to simultaneously perform the function of cleansing and reducing the buildup of microorganism, some lavatory blocks known in the prior art also constitute bleaching agents in combination with biocidal agents. Halogen release agents are a desirable component for lavatory cleansing block and the inclusion of halogen release agents in cleansing blocks is known. A halogen release agent is a compound which upon contact with water forms an oxyacid of the halogen such as a hypohalous acid (for example hypofluorous acid; hypochlorous acid; hypobromous acid). Alternatively or additionally halogen release agents may also form oxyacid ions containing a halogen such as hypohalite ions (for example hypobromite; hypochlorite; hypofluorite) in the water. As a result of such properties, halogen release agents are suitable to function as powerful sanitising and cleansing agents. However, halogen release components are highly reactive and hence it may be difficult or even dangerous to incorporate halogen release agents in comparatively higher levels (such as greater than 20% by weight) in the lavatory cleansing blocks.

One of the problems associated with inclusion of relatively higher levels of halogen releasing agent is the strong smell that is associated with relatively higher levels (greater than 20% by weight) of halogen releasing agents in lavatory cleansing blocks. As a result, the use of high levels of halogen release agents in lavatory cleansing blocks is not favourable.

Another problem associated with the inclusion of relatively higher levels of halogen releasing agents in the cleansing blocks is the danger associated with the highly reactive by-products that may be formed during the use of such cleansing blocks which could possibly cause burns. Halogen release agents are, by their nature, powerful chemically reactive species, serving as halogenating or oxidising agents. Thus, halogen release agents (i) tend to react with surface active materials and/or (ii) tend, when moistened, to evolve gas thereby losing their activity and, in many cases, destroying the physical integrity of the cleansing block. Further, halogen release agents may attack component parts of lavatories, urinals or their cisterns.

Accordingly, there is a need for an improved lavatory cleansing block that at least addresses some of the problems associated with the prior art.

SUMMARY OF THE INVENTION

The present invention in at least some embodiments provides a cleansing block for insertion in a tank of a flushing toilet in which the use of certain surface active agents together with certain halogen release agents makes possible the preparation of lavatory cleansing compositions with improved properties to address at least some of the problems associated with the prior art.

In one aspect, the invention provides a cleansing block for insertion in a tank of a flushing toilet, the block comprising (all percentages being by weight and based upon the total composition weight):

(a) 10 to 50% of a surface active component comprising one or more surface active agents including at least one alkyl sulfonate, sodium salt or at least one alkyl sulfate, sodium salt;

(b) 20 to 60% of at least one water-soluble inorganic salt;

(b) 0 to 10% colouring agent; and

(c) 0.5 to 5% of a halogen release agent comprising one or more of the following: 2, 2-dibromo-3nitrilopropionamide, N-(4-chlorophenyl)-N'- (3, 4-dichlorophenyl)-Urea; 2,4,4'-Trichlorine-2'-Hydroxyl Diphenyl Ether and 2,2-Dibromo-2-Nitroethanol.

In another aspect, the invention provides a cleansing block for insertion in a tank of a flushing toilet, the block comprising (all percentages being by weight and based upon the total composition weight):

(a) 10 to 50% of a surface active component comprising one or more surface active agents including at least one alkyl benzene sulfonate, sodium salt;

(b) 20 to 60% of at least one water-soluble inorganic salt;

(b) 0.5 to 5% colouring agent; and

(c) 0.5 to 10% of a halogen release agent comprising a non- oxidizable microbial agent comprising at least 2, 2-dibromo- 3nitrilopropionamide.

In yet another aspect, the invention provides a cleansing block for insertion in a tank of a flushing toilet, the block comprising (all percentages being by weight and based upon the total composition weight):

(a) 10 to 30% of a surface active component comprising one or more surface active agents including at least one mono- C12-14 - alkyl sulfate, sodium salt;

(b) 20 to 60% of at least one water-soluble inorganic salt;

(b) 0 to 5% colouring agent; and

(c) 0.5 to 10% of a halogen release agent comprising at least N-(4- chlorophenyl)-N'-(3, 4-dichlorophenyl)-Urea. In an embodiment, the cleansing block further comprises: (D) from 1 -65% by weight of one or more organic acids.

In an embodimdent, the surface active component further comprises one or more anionic surface active agents and/or nonionic surface active agents.

In an embodiment, the one or more organic acids are selected from a group comprising: Formic Acid, Acetic Acid, Boric Acid, Citric Acid, Oxalic Acid, Glycolic Acid, Gluconic Acid, Lactic Acid, Adipic Acid, Maleic Acid, Tartaric Acid and Succinic Acid as well as their mixtures.

In an embodiment, the surface active component is selected from one or more of the following: alkali metal paraffin sulphonates, alkali metal alkyl sulphates and alkali metal alkyl aryl sulphonates.

In an embodiment, the block further comprises: 5-20% of a binding agent. Preferably, the binding agent comprises alkyl cellulose or hydroxyl alkyl cellulose.

In an embodiment, the block further comprises: from 15 to 65% by weight of an inert filler agent.

In an embodiment, the cleansing block further comprises: from 0.5 to 20% by weight of one or more water-softening agents. In an embodiment, the block further comprises: acids, bases, salts, thickeners, preservatives, complexing agents, dyes, fragrance , perfume boosters, fillers, builders, bleaching agents, corrosion inhibitors, flush regulators, enzymes, active ingredients for inhibiting timescale deposits, active ingredients for reducing adhesion and mixtures thereof.

In an embodiment, the block comprises a defined mass having a solid, semi solid, or gel form. In another aspect, the invention provides a method of manufacturing a cleansing block, the method comprising the steps of: mixing components (a), (b), (c) and (d) to form a mixture wherein (a) comprises 10 to 30% of a surface active component comprising one or more surface active agents including at least one alkyl sulfonate, sodium salt or at least one alkyl sulfate, sodium salt; (b) comprises 20 to 60% of at least one water-soluble inorganic salt; (c) comprises 0.5 to 5% colouring agent; and (d) comprises 0.5 to 5% of a halogen release agent comprising one or more of the following: 2, 2-dibromo-3nitrilopropionamide, , N-(4-chlorophenyl)-N'- (3, 4-dichlorophenyl)-Urea; 2,4,4'-Trichlorine-2'-Hydroxyl Diphenyl Ether and 2,2-Dibromo-2-Nitroethanol;

extruding the mixture to form an extruded mass; and cutting the extruded mass to form one or more of the cleansing blocks. DETAILED DESCRIPTION

The present invention affords a cleaning block which achieves better overall properties through a combination of special active ingredients in certain critically selected quantitative ratios, although the majority of these active ingredients have already been proposed for or used in products of the type in question.

The cleaning blocks according to embodiments of the present are distinguished above all by a particularly effective rate of killing germs. The inventors have found that the specific combination of surface active components including an alky! sulfonate, sodium salt in combination with specific halogen release agents selected from the group of: 2, 2-dibromo-3nitrilopropionamide, N-(4- chlorophenyl)-N'-(3, 4-dichlorophenyl)-Urea; 2,4,4'-Trichlorine-2'-Hydroxyl Diphenyl Ether and 2,2-Dibromo-2-Nitroethanol, in specific quantitive ratios provides a dramatic improvement in reducing effective microbial concentration. Such an improvement is particularly significant for cleansing blocks containing colouring pigments which are usually prone to bleaching. The present embodiment addresses a long felt need by providing cleansing blocks that can be inserted in a tank of a flushing toilet that not only provides effective reduction in microbial concentration but also prevents de-colouring of the pigment in the cleansing block even upon dissolving in the water from the cistern by reducing the possibility of excessive bleaching.

Some of the constituents for the cleansing block from the preferred embodiments of the present invention will be described in the following passages. (a) Surfactants

The toilet cleaner block in at least some embodiments comprises at least one non-ionic surfactant, at least one alkyl sulfonate, sodium salt. Preferably, sodium dodecylbenzene sulphonate is used as a surfactant. In addition, the toilet cleaner block may comprise other additional anionic surfactants such as sodium lauryl sulfate. However, a wide variety of surfactants (anionic, nonionic, cationic, zwitterionic) may also be suitable for use in toilet cleansing blocks.

The toilet cleaner block according to the invention comprises preferably 10 to 50wt %, preferably 10 to 40 wt % alkyl sulfonate, sodium salt.

(b) Water-soluble inorganic alkali salt

Alkali salts are an important component of the cleaning blocks of at least some embodiments of the present invention. Their function is inter alia to enhance the cleaning power and to increase the specific gravity of the blocks. It is preferred to use one or more mildly acidic or alkaline or neutral alkali salts, for example sodium carbonate, sodium bicarbonate, borax, sodium sulfate and sodium chloride. Particular significance is attributed to the sodium salts and, above ail, to sodium sulfate. The content of alkali salts in the cleaning blocks of at least some embodiments is 15 to 80%, preferably 20 to 55% by weight. The salts used may contain water of crystallization to a certain extent, but are preferably used in anhydrous form, as are all the other components. (c) Water-soluble dye

Water soluble dyes may be present in the cleaning blocks in quantities of up to 10% by weight. The function of the dye is above all to provide a visual indication of the effectiveness of the blocks to the user. Dyes which do not diffuse prematurely from the cleaning blocks by virtue of their solubility are preferred. The dyes are preferably incorporated in quantities of 0.5 to 5% by weight. Suitable examples include inorganic pigments of mixed-phase types, consisting exclusively of metal oxides such as Co/AI oxide (blue) and Co/Ti/Ni/Zn oxides (Green). These pigments can be conveniently incorporated in the blocks of the invention by dispersing in the powder mixture.

(d) Halogen Release Agent

The applicants have found that the use of halogen release agents selected from one or more of: 2, 2-dibromo-3nitrilopropionamide, N-(4-chlorophenyl)-N'-(3, 4- dichlorophenyl)-Urea; 2,4,4'-Trichlorine-2'-Hydroxyl Diphenyl Ether and 2,2- Dibromo-2-Nitroethanol is particularly effective in achieving high levels of germ kill when used in combination with some specific types of surfactants as described above. The halogen release agents selected from one or more of the above chemicals also function as non-oxidizable anti-microbial agents. It is hypothesized by the inventors that one or more of these halogen release agents in combination with specific types of surfactants in some quantitative ratios provides a surprising and synergistic effect in achieving high levels of germ kill without the disadvantages associated with using halogen release agents such as bleaching, corrosion or emitting strong and undesirable odour. (d) Water-soluble organic acids

The cleaning blocks according to some embodiments may also contain solid, water-soluble, low molecular weight organic acids such as carboxylic acids for use as complexing agents. Organic acids such as citric acid and boric acid may be used as complexing agents in at least some embodiments. It has been discovered that the addition of such organic acids increase longetivity of the cleaning block to achieve a uniform release of active halogen over a commercially feasible term, for example, upto one to two months. Organic acids may be provided in quantities in the range of 10-65wt%.

(e) Perfume oil

The cleaning blocks may contain up to 15%, preferably 3 to 8% by weight of any conventional and chemically compatible perfume oil.

(f) Other ingredients In addition to components (a) to (e), the cleaning blocks according to the invention may contain at least one other auxiliary and/or additive, provided they do not adversely affect the properties of the blocks. Ingredients such as these include binding agents, plasticizing aids, dissolution regulators, cleaning enhancers and auxiliaries which make the cleaning blocks easier to produce (production facilitator). Coating compositions may also be subsequently applied to the blocks to make them easier to handle and store before use are also included in this category. The auxiliaries may be present in the blocks in quantities of up to 10%, preferably 0.1 % to 5% by weight; in particular, however, they may also be absent altogether.

Reference to the individual components in the foregoing description may describe the contribution made by the particular component to the properties of the cleaning blocks. However, such references are only meant to be interpreted as an indication of a special effect. Overall every one of the components appear to contribute to a degree to each individual property of the blocks, particularly their effectiveness in killing germs without any of the disadvantages associated with using halogen releasing agents. Thus, only the cooperation of the individual components in specified quantitative ratios in the inventive composition results in the improved properties of the cleaning blocks in accordance with embodiments of the present invention.

The lavatory cleansing block may be suitably formed by an extrusion or tabletting process in accordance with a method embodiment of the present invention. For carrying out the extrusion process, the process may comprise the steps of forming a mixture of the components of the cleansing block, as described above and extruding this mixture into a desired shape (preferably elongate such as in the shape of a rod or a bar) and then cutting the extruded rod or bar into appropriately sized pieces or blocks. Alternatively, the cleansing blocks may also be prepared by a melting and casting process. By way of example, e.g. one or more of the fusible components of the block are fuse melted which causes the non-fusible components adhere to the melt, and the resultant mixture can be cast into moulds having various shapes. The hard surface cleansing block of the invention may be further adapted for gradually releasing active constituents. By way of example, the cleansing block may be adapted for releasing the microbial agent (in particular biocide) to the surface. This effect may be achieved by providing a block that gradually erodes or dissolves when contacted or flushed with water.

EXAMPLES

Experiments were conducted to demonstrate the superior effects of non- oxidizable antimicrobial component with/without halogen release componentt for different type of lavatory cleansing blocks.

Example (Table 1 )

The examples in Table 1 illustrate compositions for a cleansing block in accordance with a preferred embodiment for use in a cistern of a flushing toilet. Samples 1 to 6 in table 1 provide a breakdown of the composition (by wt%) for a first type of coloured cleansing block in accordance with an embodiment. For coloured in-cistern lavatory cleaning block, blue dye and green dye are popularly used colours. The coloured flushed into the toilet bowl after flushing the toilet indicates that a pleasing a clean appearance to the water in the toilet bowl. Currently known toilet blocks with blue and green dyes or pigments are not stable over long periods of time due to oxidation of the halogen release agents found in prior art blocks. However, embodiment of the present invention provide a cleansing block which addresses the shortcomings of the prior art and provides a combination of specific constituent chemicals in very specific quantitative ranges that provide a cleansing block which not only achieves stable pigments in water over longer periods of time but also provide high levels of antimicrobial effect.

Samples 1 -3 and 6 use 3-5wt% 2,2-Dibromo-3-Nitrilopropionamide in combination with all the other constituents which is effective in killing 99% germs with at least 7.5ppm concentration of 2,2-Dibromo-3- Nitrilopropionamide in water. By way of example, if a 50g lavatory cleaning block lasts 30 days in cistern as its use life, 2,2-Dibromo-3-Nitrilopropionamide is 5% concentration in lavatory cleaning block and the cistern provides 3litre/6litre water for every flush then the cleaning block in samples 1 -3 and 6 will provide 50/30/6x0.05=13.89ppm, 50/30/3x0.05=27.78ppm of effective antimicrobial agent concentration and kill over than 99% germs without causing significant degradation of the pigments in the blocks.

Example Table 2

Samples 1 -6 in Table 2 illustrate compositions for a cleansing block in accordance with another preferred embodiment for use in a cistern of a flushing toilet. Samples 1 to 6 in table 2 provide a breakdown of the composition (by wt%) for a second type of cleansing block in which pigments are not provided. Coulourless or white coloured cleansing blocks for cisterns are known in the art. However, one of the problems associated with these blocks is the high level of halogen release agents that are used in the prior art blocks. The disadvantages of using halogen release agents have been discussed in previous sections. Samples 1 to 6 from Table 2 provide cleansing blocks with much lower levels of halogen release agents which are still able to achieve high levels of germ killing ability. The germ killing effect provided by the cleaning block in table 2 have undergone preliminary testing. If a 50g lavatory cleaning block lasts for up to 30 days in cistern for its use life, and a modern lavatory cistern provides 3litre/6litre water for each flush then consumption of the 50g cleansing block was found to be in the range of 50/30/6=278mg/L to 50/30/3=556mg/L By considering for maximum usage, the 50g lavatory cleaning block was diluted to be 278mg/L and germ kill testing was carried out. The test reports have indicated over 99.9% germ killing.

Example Table 3

Samples 1 -6 in Table 3 illustrate compositions for a cleansing block in accordance with another preferred embodiment for use as a block positioned in a dispenser placed along the walls of a toilet bowl. Samples 1 to 6 in table 3 provide a breakdown of the composition (by wt%) for a third type of cleansing block. Due to the placement of the cleansing blocks positioned along a rim of the toilet, the components of these blocks are available to be flushed out from dispenser only when water from the cistern is flushing.

Example Table 4

Samples 1 -6 in Table 4 illustrate compositions for a cleansing block in accordance with another preferred embodiment for use as a gel positioned in a dispenser placed along the walls of a toilet bowl. Samples 1 to 6 in table 4 provide a breakdown of the composition (by wt%) for a fourth type of cleansing block.

Example Table 5

Samples 1 -6 in Table 5 illustrate compositions of a dissolving cleansing block in accordance with another preferred embodiment. Samples 1 to 6 in table 5 provide a breakdown of the composition (by wt%) for a fifth type of cleansing block. This fifth type of block is useful for dissolving limescale in toilet bowls. In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term "comprises" and its variations, such as "comprising" and "comprised of" is used throughout in an inclusive sense and not to the exclusion of any additional features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Any embodiment of the invention is meant to be illustrative only and is not meant to be limiting to the invention. Therefore, it should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.