GB2332682A - Lavatory cleansing blocks - Google Patents

Abstract

A lavatory cleansing block comprises an anionic surface active agent and a phosphonate detergency builder. The block formulation is free of additional polyvalent metal ions. Foam formation in hard water environments is improved.

Description

Lavatory Cleansing Blocks The present invention relates to lavatory cleansing blocks. The invention is particularly applicable to in-tank blocks which are immersed in the cistern of a lavatory or urinal, but it is also applicable to rim blocks, which are positioned under the rim of the lavatory bowl and free standing blocks which are placed in a urinal. The blocks come in various forms, they may be dropped into the cistern, held in a container in or on the cistern or under a rim, have a water soluble wrapping, etc.

With the rim blocks, the active ingredients are dispensed when the lavatory is flushed, and subsequently as water on the block drips into the bowl. With in-tank blocks the active ingredients pass into solution gradually, as the block sits in the water. Some mixing occurs during emptying and filling of the cistern.

Lavatory cleansing blocks are generally required to perform one or more of various functions, including physical cleaning of the lavatory bowl, disinfecting, deodorising and the reduction of limescale formation.

A wide range of ingredients are available to meet these requirements.

In selecting the block ingredients it is necessary to ensure that the ingredients themselves do not interact adversely, to provide a composition which can be made safely, and to provide a block with an acceptable lifetime.

In addition, it is desirable to provide an indicator for the user which will give an easily recognised signal that the block is at the end of its life.

For example, the block may incorporate a dye to colour the water. However, suitable dyes may interact adversely with disinfecting agents, typically a bleach, resulting in unacceptable colour quality. A foaming agent will also provide a signal to the user, as well as performing a cleansing function. A chlorine bleaching agent may provide a smell and a perfume may be included to provide a different, or more pleasant smell..

The blocks themselves are typically extruded and cut to size. The pressure and temperature of the extrusion process can adversely affect the block ingredients. Liquid or liquifiable process aids may be provided to aid the extrusion process.

It is important to provide a block with an acceptable lifetime, which will generally be several weeks. To extend the lifetime of the block, low solubility compounds or hydrophobes may be utilised, or the block container may allow limited contact with the water.

Yet another requirement is to provide a block which has an acceptable performance over a wide geographic area. Typically the block composition may be modified to suit different climatic conditions experienced from one country to another, but it is desirable to sell the same block composition over a country wide area. Water hardness or softness is known to have a significant impact on block lifetime.

EP-A-184416 recognises that the in-use life of lavatory cleansing blocks containing anionic surface active agents is longer in hardwater environments. To overcome this variation in life, a water soluble polyvalent metal salt is incorporated in the block. The preferred ion is Mg2+. EP-A184416 speculates that by creating a hard water environment, in the block, the longer lifetime is obtained when the block is immersed in a soft water environment.

Paradoxically, the anionic surface active agents are perceived by the user to perform better in soft water environments because they produce a greater quantity of foam, and a longer foam lifetime.

Thus the present invention stems from the realisation that the in-use performance of the anionic surfactant containing lavatory block can be improved in hard water areas by creating a soft water environment for the block, which is quite opposite to previous thinking. By soft water environment we mean an environment in which the effective or active concentration of water hardness ions, such as Ca2+ and Mg2+ is low.

A first aspect of the invention provides a lavatory cleansing block which is substantially free of added polyvalent metal ions and comprises (i) an anionic surface active agent, and (ii) a phosphonate.

Detergency builders are known in the art of laundry powders and serve to reduce the active concentration of the calcium or magnesium ions.

Preferably the ions are held in solution, and a chelating agent is particularly preferred. We have found that a phosphonate is particularly suitable for achieving a similar effect in a lavatory cleansing block.

The anionic surfactant may be present in an amount from 5 to 85% by weight of the block, preferably 15 to 60% by weight, more preferably 20 to 50% by weight of the block, and particularly about 40% by weight of the block.

The anionic surface active agent used in the blocks of the present invention may be, for example, an alkali metal, typically sodium, paraffin sulphonate; alkali metal alkyl sulphate or alkali metal alkyl aryl sulphonate; especially an alkali metal alkyl benzene sulphonate. In particular, sodium dodecyl benzene sulphonate may be mentioned as it is a readily commercially available anionic surface active agent.

Some commercially available anionic surface active agents contain polyvalent metal salts as process aids or fillers and the use of these surface active agents is within the scope of this invention.

The phosphonate is preferably present in an amount of at least 2% by weight of the block, preferably 2 to 15% and more preferably 3 to 10% by weight.

The block preferably contains an inert filler. Preferably an alkali metal inorganic filler such as sodium sulphate, sodium carbonate, sodium bicarbonate, sodium chloride or borax is used. Organic fillers such as urea may also be used. The filler is preferably present in an amount up to 75% by weight of the block, preferably 5 to 50% and more preferably 30 to 40%.

Preferably the detergency builder and inert filler combined comprise from 30 to 60% by weight of the block, preferably 40 to 50% and more preferably about 45%.

The blocks of the invention will often contain a dyestuff or other colouring agent, such as a pigment, in order to impart a pleasant colouration to the water and also to provide an additional indication to the user when the block has exhausted (i.e. on exhaustion of the block the water becomes colourless), the other indication being the absence of foam.

Accordingly, the block preferably contains water soluble dyestuff, suitably in an amount of up to 20% by weight, preferably in an amount of from 1 to 15% by weight, more preferably from 1 to 10% by weight. Suitable dyestuffs include, for example, Acid Blue 9, Acid Blue 1, Acid Blue 7 and Acid Yellow 23.

The blocks may also contain perfumes to impart an acceptable odour to the flushed water. The perfume may be a solid perfume, which term is intended to include micro-encapsulated perfume (i.e. liquid perfumes contained in a water-soluble microcapsule) or other solid perfume materials such as paradichlorobenzene. Alternatively the perfume may be a liquid and in this case the term liquid perfume is intended to cover not only perfumes order se but solutions or perfumes in solvents therefor. The total amount of perfume should not be more than 35% by weight and is preferably from 2 to 20% by weight. It may be noted that the term "perfume" is intended to refer to any material giving an acceptable odour and thus material giving a "disinfectant" odour such as pine oils, terpinolenes or paradichlorobenzene may be employed. It may be further noted that liquid perfumes are frequently substantially water-insoluble and thus they may serve as a part, or indeed all, of the water-solubility control agent. In other words, a single material, such as pine oil, may serve both as perfume and a solubility control agent.

The blocks in accordance with the invention may also contain germicides. Suitable germicides include, for example, formaldehyde release agents and chlorinated phenols. These compounds may be present in the blocks in amounts of up to 20% by weight, preferably from 0.1 to 15% by weight.

The block may also contain a rheological control agent. Examples of such agents are clay and water soluble or water dispersible organic polymers. Particularly preferred rheological control agents are natural polysaccharide gums, such as guar gum. The gum also serves as a cohesion agent, a water solubility control agent and a processing lubricant aid.

It is particularly preferred that the block contains a halogen release agent. Embodiments include N-chlorosuccinimide, calcium hypochlorite, chloramine T, dichlorodimethyl hydantoin, bromochlorodimethyl hydantoin, and chlorinated isocyanuric acid derivatives such as sodium dichloroisocyanurate and trichloroisocyanuric acid, and chlorinated sodium tripolyphosphate. Preferably the halogen release agent is present in an amount of from 2 to 65% by weight, preferably 10 to 50% by weight and more preferably from 15 to 40% by weight. A mixture of halogen release agents may be used. The halogen release agent may be incorporated by manufacturing a two part block, with the phosphonate in one part and the halogen release agent in the other part.

The blocks in accordance with the invention are conveniently produced by a compression process, especially an extrusion process comprising forming a mixture of the component for the block, extruding this mixture into rod or bar form and subsequently cutting the rod or bar into portions or blocks of the desired size. When employing an extrusion process it is most desirable that the starting mixture contains a liquid component or a solid component capable of being liquefied under extrusion conditions, generally in an amount of from 1 to 20% by weight, preferably from 3 to 15% by weight, of the total mixture. Most conveniently such a liquid component comprises a perfume component and/or solubility control agent. Thus, for example, pine oil may serve not only as a perfume and solubility control agent but also as an extrusion processing aid. The blocks of the invention are suitably from 20 to 150 gums in weight preferably from 30 to 70 gms in weight.

The invention further provides a method for cleansing a lavatory or urinal which comprises utilising a block in accordance with the invention.

In order that the invention may be well understood the following Examples are given by way of illustration only. In the Examples all parts are by weight.

Examples Lavatory cleansing blocks were prepared by extruding compositions as detailed in the following Table and cutting the extrudate in blocks weighing 50 g.

A B C D Sodium Dodecylbenzene Sulphonate (80%) 40.0 40.0 40.0 40.0 Sodium Sulphate 44.1 39.1 34.1 29.1 Guar Gum 5.0 5.0 5.0 5.0 Acid Blue 9 3.4 3.4. 3.4 3.4 Pine Oil 5.5 5.5 5.5 5.5 Mineral Oil 1.8 1.8 1.8 1.8 Orthobenzylparachlorophenol 0.2 0.2 0.2 0.2 * Phosphonate - 5 10 15 100 100 100 100 *Where Phosphonate is selected from (a) 1-Hydroxethylidene -1, diphosphonic acid, tetrasodium salt (Dequest49 2016D ex Monsanto) (b) Ethylene diamine tetra (methylene phosphonic acid) (Dequest 2041 ex Monsanto) (c) 2 -Phosphonobutane- 1,2 ,4-tricarb oxylic acid, tetrasodium salt (Bayhibit AM ex Bayer) The compositions B, C and D using 5, 10 or 15% respectively of a listed phosphonate provided improved foaming compared to the control composition A in hard water.

Lavatory cleansing blocks were prepared according to the following formulations E and F.

E F Sodium Dodecylbenzene Sulphonate (80%) 48.0 48.0 Sodium Sulphate 23.4 28.4 Guar Gum 3.0 3.0 Acid Blue 9 3.4 3.4 Pine Oil 7.0 7.0 Arbocell B800 5.0 5.0 Orthobenzyiparachlorophenoi 0.2 0.2 Hostapur SAS93G 5.0 5.0 Dequest 2016D 5.0 Nil 100 100 The blocks were immersed in hard and in soft water to simulate immersion in a lavatory cistern. The water was then sampled and shaken in a measuring cylinder and the height of the foam observed for a period of time, giving the following results: HARD WATER SOFT WATER EXAMPLE Omin. lmin. Smin. Omin. lmin. Smin.

E 32mm 30mm 26mm 68mm 66mm 60mm F 23mm 2lmm 20mm 55mm 53mm 45mm The formulation according to the invention, example E, gave improved foaming in both hard and soft water

Claims (8)

1. CLAIMS: 1. A lavatory cleansing block which is substantially free of added polyvalent metal ions and comprises (i) an anionic surface active agent, and (ii) a phosphonate.
2. 2. A lavatory cleansing block as claimed in claim 1, comprising at least two per cent by weight of the phosphonate.
3. 3. A lavatory cleansing block as claimed in claim 1 or 2, comprising from 2 to 15 percent by weight of the phosphonate.
4. 4. A lavatory cleansing block as claimed in claim 3, comprising from 3 to 10 percent by weight of the phosphonate.
5. 5. A lavatory cleansing block as claimed in any one of claims 1 to 4, wherein the phosphonate is 1-Hydroxethylidene -1, diphosphonic acid, tetrasodium salt.
6. 6. A lavatory cleansing block as claimed in any one of claims 1 to 6, further comprising a halogen release agent.
7. 7. A lavatory cleansing block as claimed in any one of claims 1 to 6, wherein the block is substantially free of polyvalent metal ions.
8. 8. A lavatory cleansing block substantially as hereinbefore described with reference to example B, C, D or E.