Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1999-09-22
2001-09-18
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S380000, C510S192000
Reexamination Certificate
active
06291411
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for cleaning toilet bowls and to a composition, having bleaching and lime scale removal properties, which is particularly suitable for use in the method.
BACKGROUND ART
Compositions based on hypochlorite bleach are well-known for use in cleaning hard surfaces which are subject to staining and in particular they are known for use as toilet cleaners. The bowls of flushable toilets are subject to deposition of lime scale in hard water areas. This lime scale is predominantly calcium carbonate but may become discoloured by incorporation of coloured metal ions such as ions of Fe, Mn and by bacterial films and human waste deposits on the lime scale or on the surface of the toilet bowl. Aqueous solutions of sodium hypochlorite, usually containing a thickener to increase viscosity, are widely used in treating toilet bowls. The hypochlorite bleaches the lime scale so that it is less noticeable but does not remove it. The hypochlorite also acts as a disinfectant and users often rely on the odour of chlorine released by hypochlorite bleaches as confirmation that disinfection is taking place.
It is possible to remove lime scale by the action of acids but there is a risk of the release of excessive quantities of toxic chlorine gas if such acidic cleaners are inadvertently mixed with sodium hypochiorite bleach. When used alone such acidic cleaners do not produce the slight chlorine odour which reassures users that the toilet bowl is being disinfected. However, there has been no consideration of the possibility of providing some ability to remove lime scale in a hypochlorite bleach.
Sodium salts are generally the cheapest of the alkali and alkali metal salts (with the exception of such insoluble materials as calcium and magnesium carbonates) and in general sodium salts are used whenever a water soluble alkali metal or alkaline earth metal salt is required unless there is some known reason for using another salt. The case of hypochlorite bleaches is no exception and the commercially available toilet cleaners based on hypochlorite bleach use sodium hypochlorite.
Derwent WPI abstract accession number 87-032288/05 of JP-A-61-287995 discloses a two -pack cleaning composition for a flush toilet. One pack comprises bleaching agent and the other pack comprises non-ionic surfactant, water-soluble inorganic salt and water-insoluble inorganic salt. The bleaching agent may be NaClO, KClO, LiClO, Ca hypochlorite, or Na or K dichloroisocyanurate. The use of a two pack composition will be inconvenient. The abstract does not suggest that the use of hypochlorites other than NaOCl has any advantages which would justify the increased cost.
Derwent WPI abstract accession number 87-032283/05 of JP-A-61-287990 discloses a cleaning composition which may be used in flushing toilets, and may be in the form of a liquid, solid, paste, or granules. It comprises a chlorine bleach and and an alkali metal alkyl succinate. The chlorine bleach may be calcium hypochlorite, or sodium or potassium dichloroisocyanurate.
The chlorine bleaches disclosed in this abstract have low solubility in water and are generally supplied commercially as solids. However an important market for chlorine bleaches is as pourable liquids which are poured by the user into the toilet bowl. For this purpose chlorine bleaches having high solubility in water are desirable, namely the water soluble hypochlorite bleaches. The abstract contains nothing which suggests that the use of potassium as opposed to sodium dichloroisocyanurate gives any advantage in lime scale removal. As the first chlorine bleach mentioned is calcium hypochlorite the abstract does not appear to be concerned with the problems caused by the presence of calcium ions.
It is known that various compounds will sequester metal ions, including calcium ions. However, sequestering agents are usually employed to prevent metal ions, such as calcium, precipitating from aqueous solution. In a conventional liquid toilet cleaner poured by the user from a container into the bowl of a flushing toilet the only water affected by the contents of the liquid cleaner is the water initially held in the toilet bowl and the first flush of water used to remove the toilet cleaner. Most of the water passing through the toilet bowl will be unaffected by the contents of the liquid cleaner. There would thus appear to be no advantage in introducing sequestering agents into conventional liquid hypochlorite bleach.
We have now found that the bowls of flushing toilets can be more effectively cleaned by treating them with a liquid hypochlorite bleach with a defined additive.
DISCLOSURE OF INVENTION
According to one aspect of the present invention there is provided a method of cleaning a flushable toilet bowl which comprises
a) pouring into the interior of the toilet bowl from a container an aqueous liquid composition comprising a hypochlorite bleach and a bleach-resistant organic sequestering agent having a molecular weight below 1500 which sequesters calcium, and
b) subsequently flushing the toilet.
The process makes use of a single pack pourable liquid composition. If it contains more than one phase then the phases should be so dispersed that they are stable on storage. Preferably the composition is a homogeneous liquid phase, which may have a high viscosity.
According to a further aspect of the invention there is provided a single pack pourable aqueous liquid hypochlorite bleach cleaning composition wherein at least 50% by weight of the hypochlorite comprises potassium hypochlorite and which liquid contains a bleach-resistant organic sequestering agent having a molecular weight below 1500 which sequesters calcium.
The hypochlorite bleach used in the process of the present invention may be a sodium hypochlorite or potassium hypochlorite.
The hypochlorite bleach preferably includes potassium hypochlorite. As the composition is an aqueous solution the potassium ions are not directly associated with the hypochlorite ions in solution. Where other metal cations are present in solution the quantity of potassium hypochlorite is taken to be that corresponding to matching all the available potassium with all the available hypochlorite. If there is an excess of potassium ions then the amount of hypochlorite will determine the amount of potassium hypochlorite considered to be present. If there is an excess of hypochlorite then the amount of potassium ions will determine the amount of potassium hypochlorite considered to be present. Preferably at least 50% by weight of the hypochlorite present is present as potassium hypochlorite, more preferably at least 60%, yet more preferably at least 80% of the hypochlorite is present as potassium hypochlorite. Preferably all the hypochlorite is present as potassium hypochlorite and hypochlorite is the only chlorine bleaching agent present. Potassium hypochlorite may be the sole hypochlorite used to manufacture the toilet cleaner composition for use in the invention.
The composition contains a sequestering agent to sequester metal cations especially calcium ions but also iron and manganese ions. The sequestering agent is bleach-resistant i.e. it must of course be sufficiently stable in the presence of chlorine bleach to retain a useful level of sequestering activity after storage.
Certain polymers containing carboxylic acid groups have activity as crystal growth modifiers, i.e. they modify the growth of crystals which could lead to scale formation so that the crystals are retained in suspension and are not deposited. Such polymers are, however, not satisfactory for removing scale which has already formed. The sequestering agents of the present invention have molecular weights (weight average molecular weight) of below 1500, preferably below 1000, more preferably below 500.
The sequestering agents will preferably contain a hetero-atom, i.e. an atom other than carbon, which atom is bonded to at least two other atoms, preferably carbon atoms. Examples of hetero-atoms are N, P, S, O, B, Si. The preferred hetero-atoms are N, P, and S.
A
Avery Richard W.
Callaghan Ian C.
Moodycliffe Timothy I.
Gupta Yogendra N.
Petruncio John M
S. C. Johnson & Son Inc.
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