GB2300643A

GB2300643A - Hard Surface Cleaners

Info

Publication number: GB2300643A
Application number: GB9509519A
Authority: GB
Inventors: Thomas Weibel
Original assignee: Reckitt and Colman Inc
Current assignee: Reckitt Benckiser LLC
Priority date: 1995-05-11
Filing date: 1995-05-11
Publication date: 1996-11-13
Also published as: GB9509519D0; AR001829A1; ZA963733B

Abstract

A thickened stable hard surface cleaner comprises (a) from 10 to 30% abrasive particles, (b) from 0.5 to 2.5% of a chlorine-containing bleach, (c) from 0.5 to 3% of a thickening system comprising from 0.5 to 3%, based on the weight of the composition, of a cross-linked polyacrylate resin having a molecular weight in the range of 1,000,000 to 10,000,000 and from 0 to 1.5% of a synthetic smectite clay resembling natural clays of the hectorite class, (d) from 0.25 to 2.0% of a bleach stable surfactant system comprising mainly anionic surfactants, (e) from 0 to 3% of an electrolyte selected from the group comprising sodium or potassium carbonates or silicates, and (f) sufficient amount of sodium or potassium hydroxide to attain a pH in the range of 11.5 to 13.5. The bleach is based on hypochlorite. The surfactant may be a sulphate or sulphonate.

Description

IMPROVEMENTS IN OR RELATING TO CHEMICAL COMPOUNDS This invention relates to abrasive-containing hard surface scouring cleansers containing hypochlorite bleach which are thickened with polyacrylate acid resins. More particularly, it relates to such compositions which maintain high active chlorine stability over a long period of time.

Polymeric thickeners are often added to liquid products containing hypochlorite bleach in order to enhance their rheological properties so as to make them more suitable for use on non-horizontal surfaces. Among the problems encountered with such compositions is the fact that liquids containing hypochlorite bleach are destructive to most synthetic and natural thickeners. In recent years, there have been developed a number of thickened bleach products incorporating, as thickeners, certain polyacrylates and certain natural or synthetic clays of the smectite type which are somewhat less subject to degradation by the hypochlorite bleach.

However, many of these polymeric substances, particularly the lower molecular weight polyacrylates, do not substantially increase viscosity. Furthermore, even though these compositions may show initial stability, they tend to degrade, with a resultant loss of chlorine activity within a few months. Therefore, in commercial practice, unless these products are used within a relatively short period of time, they lose their effectiveness as cleaning agents.

The B.F. Goodrich Company produces and distributes a series of Carbopol polyacrylate resins which are useful in the formulation of thickened sodium hypochlorite cleaning compositions. These Carbopol resins generally do not promote the degradation of the available chlorine in the solutions but, on the other hand, they do not prevent normal degradation from occurring.

Accordingly, it is an aim of this invention to provide a thickened abrasive-containing bleach cleansing composition with enhanced stability. Further objects include thickened bleach compositions which do not exhibit phase separation or loss of chlorine activity over substantial periods of time.

According to the invention, there is provided an aqueous hard surface scouring cleaner composition comprising (a) from 10 to 30% abrasive particles, (b) from 0.5 to 2.5% of a chlorine-containing bleach, (c) from 0.5 to 3% of a thickening system comprising from 0.5 to 3%, based on the weight of the composition, of a cross-linked polyacrylate resin having a molecular weight in the range of 1,000,000 to 10,000,000 and from 0 to 1.5% of a smectite clay resembling natural clays of the hectorite class, (d) from 0.25 to 2.0% of a bleach-stable surfactant system comprising mainly anionic surfactants, (e) from 0 to 3% of an electrolyte selected from the group comprising sodium or potassium carbonates or silicates, and (f) sufficient amount of sodium or potassium hydroxide to bring pH in the range of 11.5 to 13.5.These compositions will have an apparent viscosity as measured on a Brookfield RVTDV-II with a #4 spindle at 20 rpm of 3-12 Kcps and at 1 rpm of 30-200 Kcps.

The abrasive component of the formulation is necessary for physically scouring the stains from surfaces. The abrasive agent should be present in amounts of from 10 to 30% by weight of the compositions; preferably, the abrasive agent is present in amounts ranging from 15 to 25%. Any suitably base-stable abrasive agent may be used. Preferred abrasives include calcium carbonate but harder abrasives such as a perlite, silica sand and various other insoluble, inorganic particulate abrasives can be used, such as quartz, pumice, feldspar, tripoli and calcium phosphate.

Particle size will range from average particle size of 10 to 500 microns, preferably from 10 to 100 microns, and more preferably-from 15 to 75 microns. Particle hardness of the abrasives can range from Mohs hardness of 2-8, more preferably 3-6. Abrasives are generally insoluble inorganic materials (although there are some organic abrasives, such as corn cobs, rice hulls, melamine granules, urea formaldehyde etc.). Especially preferred is calcium carbonate, also known as calcite. Calcite is available from numerous commercial sources such as Georgia Marble Company, and has a Mohs hardness of about 3. Typically, a size of U.S. 140 mesh is selected, although others may be appropriate.

The scouring composition of this invention contains a chlorine oxidising bleach derived from a hypochlorite.

Generally, the hypochlorite component may be provided by a variety of sources which include sodium, potassium, lithium and calcium hypochlorites, chlorinated trisodium phosphate dodecylhydrate, potassium and sodium dichloroisocyanurate and trichlorocyanuric acid. The preferred sources are sodium or potassium hypochlorite, particularly sodium hypochlorite. The hypochlorite is present in the composition in an amount equal to 0.5 to 2.5% by weight of the composition. Preferably, the hypochlorite may form 0.75 to 2.0% of the composition.

The hypochlorite component which is preferably present in the composition contains low levels of salts such as chlorides, which would tend to increase instability of the composition. For this reason, the present invention avoids or minimises the use of hypochlorite bleaches formed by methods which common generate salts such as sodium chloride.

Interaction of the cross-linked polyacrylate resin with the hypochlorite component of the composition is particularly important for maintaining the desirable characteristics of thickening and stability. In this regard, certain salts of the hypochlorite components, most notably sodium chloride, have been found to interfere with phase stability of the polymer and its ability to achieve thickening within the composition.

Accordingly, the invention contemplates careful selection of the hypochlorite component in the composition for enhancing both the phase stability and thickening characteristics of the cross-linked polyacrylate resin.

In order to avoid the presence of salts such as sodium chloride within the compositions, the preferred hypochlorite component is preferably selected or formed in a manner avoiding the presence of undesirable salts.

For example, ordinary hypochlorite bleaches are commonly formed by bubbling chlorine gas through liquid sodium hydroxide to result in formation of the corresponding hypochlorite. However, such reactions are undesirable for the present invention since they commonly result in formation of sodium chloride.

The present invention thus contemplates the use of hypochlorites formed in other ways, such as by reaction of hypochlorous acid with sodium hydroxide or other metal hydroxides in order to produce the corresponding hypochlorite with water as the only substantial byproduct. Sodium hypochlorite bleach produced in this manner is available from a number of sources, for example Olin Corporation which produces sodium hypochlorite bleach as a 36% solution in water, and sold under the trademark Hypure.

It is specifically contemplated that the hypochlorite component of the invention either avoid the inclusion of any chloride salt or include such chloride salt only within a range of up to about 5% by weight of the hypochlorite component.

The hypochlorite component and any salt present within the composition are the principal sources of ionic strength for the composition. The ionic strength of the composition has an effect on thickening; if the percentage of salt exceeds 5% of the total composition, it becomes difficult to achieve desirable thickening.

Moreover, ionic strength also has some effect on stability of the composition; however, the effect of ionic strength on stability is minimal relative to the effects of the cross-linked polyacrylate polymers and the polymer stabiliser. In summary, the ionic strength of the compositions of the present invention is maintained preferably less than 5 g-ions/Kg, more preferably less than 3 g-ions/Kg.

In addition to enhancing the phase stability of the composition, provided primarily by the cross-linked polyacrylate polymers, the hypochlorite component also acts as a cleaning agent.

The thickening system for the compositions of this invention include a cross-linked polyacrylate polymer preferably of the type sold by the B. F. Goodrich Company under the trademark Carbopol and by 3V Chemical Company under the trademark Polygel. These polymeric resins should have a molecular weight in the range of from 1,000,000 to 10,000,000 preferably from 1,500,000 to 5,000,000. A particularly suitable polymeric resin is Carbopol 695, which has a molecular weight of about 3,000,000.

These cross-linked polyacrylate polymers are generally characterised as acrylic acid polymers which are non-linear and water-dispersible while being crosslinked with an additional monomer or monomers in order to exhibit a molecular weight in the desired range.

Preferably, the polymers are cross-linked with a polyalkenyl polyether, the cross-linking agents tending to interconnect linear strands of the polymer to form the cross-linked resin. It has been found that, for the purposes of achieving good long term stability, without the loss of chlorine effectiveness, the polymeric crosslinking agent must be carefully chosen within the foregoing parameters.

The thickening system comprises from 0.5% to 3% of the composition, preferably from 1% to 2.5% thereof.

Preferably, the thickening system can comprise, in addition to the cross-linked polyacrylate polymer, up to 50% of its weight of a synthetic smectite-type clay similar to hectorite in structure and composition. A synthetic, rather than a natural clay is preferably used, in order to avoid degradation of the composition owing to small amounts of impurities which may be found in natural products. The preferred synthetic smectite clays for use in this invention are sold under the trademark Laponite by Southern Clay Products, Inc. Particularly useful are Laponite RD and Laponite RDS, with Laponite RD being especially preferred because it contains no phosphates.

In terms of the scouring compositions of this invention, the preferred amount of synthetic smectite clay is from 0.25 to 1.5 weight %, more preferably about 1.0%.

Surfactants are added to the composition for supplemental thickening and/or for non-thickening purposes such as cleaning, improved stability, etc.

Bleach stability in the presence of the hypochlorite component is the basic criterion for selecting the surfactants to be included in the composition.

Generally, a wide variety of surfactants may be sufficiently stable in the presence of hypochlorite bleaches and these include betaines, sarcosinates, taurates, alkyl sulphates, alkyl sulphonates, alkyl acyl sulphonates, alkylphenol ether sulphates, alkyl diphenyl oxide sulphonates, alkyl phosphate esters, etc.

Generally, the surfactant systems will comprise principally anionic surfactants, but they may also include up to 20% of non-ionics and/or amphoterics.

Bleach-stable anionic surfactants useful in the present invention and which are especially stable in the presence of hypochlorite include water soluble alkali metal alkyl sulphates, alkyl sulphonates and alkylbenzene sulphonates, particularly the sodium salts of those having from 8 to 18 carbon atoms in the alkyl group, and sodium alkyl sarcosinate salts in which the alkyl group is a saturated hydrocarbon chain having from 7 to 17 carbon atoms. A preferred sarcosinate is sodium lauryl sarcosinate, sold under the trademark Hamposyl L30. A preferred alkyl sulphonate is the product sold by Dow Chemical Company under the Dowfax 2A-1 which is principally sodium dodecyl diphenyloxide disulphonate.

Examples of other organic anionic non-soap surfactants include sodium C10-C18 alkylsulphates such as sodium dodecylsulphate and sodium tallow alcoholsulphate; sodium C10-Cl8 alkanesulphonates such as sodium hexadecyl,l-sulphonate and sodium C12-Cl8 alkylbenzenesulphonates such as sodium dodecylbenzenesulphonate. The corresponding potassium salts may also be employed. The amount of surfactant in the compositions of this invention range from 0.25% to 2%, preferably from 0.5 to 1.5%.

It is also necessary to employ a stabiliser for the purpose of achieving optimum stability of the solution and for pH adjustment. A sufficient amount of sodium or potassium hydroxide should be added to provide a pH in the range of from 11.5 to 13.5, preferably from 12 to 13.

Optional ingredients in the composition include an electrolyte such as sodium or potassium carbonate or silicate, in amounts ranging up to 3% of the composition.

The hypochlorite composition preferably includes a bleach stable fragrance component and more preferably a bleach stable fragrance component which is relatively more volatile than the oxidants included in the hypochlorite component of the composition which are responsible for bleach odours.

The scouring compositions of the present invention together with the preferred cross-linked polyacrylate polymers for achieving combined thickening and stability may also include other components either for enhancing one or more of these effect or for other purposes. For example, additional adjuncts in the composition may include buffers, builders, colourants, fluorescent whitening agents, pigments, etc. However it is again noted that such adjuncts must be selected to the extent that they do not substantially interfere with the preferred characteristics of the present invention as described above.

The scouring composition of the instant invention can be prepared by admixing the above-described essential and optional components together in the appropriate concentrations in any order by any conventional means normally used to form thickened compositions. Some shear agitation is, of course, necessary to ensure preparation of the compositions of this type.

This invention will be better understood by reference to the following examples which are here included for illustrative purposes and are not intended to be limitations.

EXAMPLES I and II I II weight % weight % Carbopol 695 1.0 0.5 Laponite RDS 0 1.0 Potassium Carbonate 0 0 Potassium Hydroxide 0 0.9 Sodium Silicatel 2.0 0 Sodium Hydroxide 1.1 0 NaOC1 1.1 1.1 CaCO3 20 20 DDPES2 0.55 0.55 TiO2 0.4 0.4 Fragrance 0.15 0.15 Water 73.7 75.4 values given for anhydrous basis (100* actives) for one type which has weight ratio SiO2/Na2O of 3.22. Such products are often added as liquids with solids content of 30 to 50%.

2Dodecyl Diphenyloxide Disulphonate 100% basis is given in the table. Product is commonly added as Dowfax 2A1 which has 45% actives and 55% water. Dowfax 2A1 must be added at 1.2% of total formulation to achieve the level in the table.

Claims

1. An aqueous hard surface scouring cleaner composition having an apparent viscosity as measured on a Brookfield RVTDV-II with a i4 spindle at 20 rpm of 3 12 Kcps and at 1 rpm of 30-200 Kcps, said composition comprising, on a weight basis: (a) from 10 to 30% of abrasive particles; (b) from 0.5 to 2.5% of a chlorine containing bleach; (c) from 0.5 to 3% of a thickening system comprising from 0.5 to 3% based on the weight of the composition of a cross-linked polyacrylate resin having a molecular weight in the range of 1,000,000 to 10,000,000 and from 0 to 1.5% of a smectite clay; (d) from 0.25 to 2% of a bleach stable surfactant system comprising mainly anionic surfactants; (e) from 0 to 3% of a buffer/electrolyte selected from the group consisting of sodium or potassium carbonates or silicates, and mixtures thereof; and (f) sufficient amount of sodium or potassium hydroxide to provide a pH of from

11.5 to 13.5.

2. A composition according to claim 1 in having an ionic strength of less than 5 g-ions/Kg.

3. A composition according to claim 2 in which the ionic strength is less than 3 g-ions/Kg.

4. A composition according to claim 3 in which the ionic strength is less than 1.5 g-ions/Kg.

5. A composition according to any one of the preceding claims in which the chlorine containing bleach is a hypochlorite.

6. A composition according to any one of the preceding claims in which the hypochlorite is sodium hypochlorite.

7. A composition according to any one of the preceding claims comprising from 15 to 25% of abrasive particles.

8. A composition according to any one of the preceding claims in which the average size of the abrasive particles is from 15 to 75 microns.

9. A composition according to any one of the preceding claims in which the cross-linked polyacrylate resin has a molecular weight of from 1,500,000 to 5,000,000.

10. A composition according to claim 9 in which the resin has a molecular weight of about 3,000,000.

11. A composition according to any one of the preceding claims which comprises from 0.25 to 1.5 weight % of synthetic smectite clay.

12. A composition according to claim 11 which comprises

1.0 weight % of synthetic smectite clay.

13. A composition according to any one of the preceding claims which comprises 0.75 to 2.0% of a hypochlorite bleach.

14. A composition according to any one of the preceding claims in which the surfactant system consists of anionic surfactants and is present in an amount of from 0.5 to 1.5 weight % of the composition.

15. A composition according to claim 14 in which the anionic surfactants are selected from the group consisting of sodium C8 to C18 alkyl sulphates, sodium C8 to C18 alkyl sulphonates, sodium C8 to C18 alkylbenzenesulphonates, sodium alkyl sarcosinate salts in which the alkyl is a saturated hydrocarbon chain having from 7 to 17 carbon atoms, and mixtures thereof.

16. A composition according to any one of the preceding claims in which the pH is from 12 to 13.

17. An aqueous hard surface cleaner, substantially as herein described with reference to any one of the Examples.