IMPROVEMENTS RELATING TO HARD SURFACE CLEANING COMPOSITION

Abstract: The invention relates to use, in a plastics cleaning composition comprising nonionic surfactant, of a water soluble anionic polymer as an agent to retard the propagation of surface cracks and provides a method for cleaning plastics surfaces which comprises the step of treating the surface with a cleaning composition of pH 2-10, comprising: a) 1-30 wt.% nonionic surfactant, b) 0.005-5 wt.% of a water soluble, anionic polymer having an average molecular weight less than 1,000,000, wherein, the ratio of polymer:nonionic is 0.1:1 or less.

Description: IMPROVEMENTS RELATING TO HARD SURFACE CLEANING COMPOSITION Technical Field The present invention relates to general purpose, hard surface, liguid cleaning compositions comprising nonionic surfactants and polymeric components. In use, these compositions may come into contact with plastic surfaces such as the surfaces of baths, worktops and the like. Background of the Invention Compositions for cleaning hard surfaces generally comprise one or more nonionic surfactants as cleaning agents involved in the removal of soil from the surface. A broad range of nonionic surfactants are known and used in cleaning compositions. For example, these surfactants typically comprise alkoxylated alcohols described as compounds produced by the condensation of alkylene oxide groups, which are hydrophilic in nature, with an organic hydrophobic compound which may be aliphatic or alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield a water-soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements. Particular examples include the condensation product of aliphatic alcohols having from 8 to 22 carbon atoms in either straight or branched chain configuration with ethylene oxide, such as a coconut oil ethylene oxide condensate having from 2 to 15 moles of ethylene oxide per mole of coconut alcohol; condensates of alkylphenols whose alkyl group contains from 6 to 12 carbon atoms with 5 to 25 moles of ethylene oxide per mole of alkylphenol. It is known to incorporate components into a nonionic surfactant-based composition with the intention that deposition of such components onto surfaces will provide a protective layer against soiling in a one step cleaning operation. Our Patent Application WO 94/26858 discloses how certain anionic polymers can be used, together with nonionic surfactants, both to improve initial cleaning and to prevent soil redeposition on hard surfaces which have been cleaned with compositions comprising these polymers.. Nonionic-based cleaning compositions can also contain perfumes to promote user acceptance and mask malodours and solvents to assist in cleaning. It is believed that the presence of nonionic surfactants, particularly in combination with solvents, promotes surface damage in plastics materials which have been stressed during use or manufacture. This surface damage can cause a loss of shine and/or structural failure of the materials. The present invention is concerned with, overcoming at least in part, the problem of surface damage due to nonionic-surfactant containing compositions both in the presence or absence of solvents. Brief Description of the Invention We have now determined that anionic polymers have a protective effect against surface damage on plastics materials which occurs in the presence of nonionic surfactants. Accordingly the invention provides for the use, in a plastics cleaning composition comprising nonionic surfactant, of a water soluble anionic polymer as an agent to retard propagation of surface cracks. A further aspect of the present invention relates to a method for cleaning plastics surfaces which comprises the step of treating the surface with a cleaning composition of pH 2-10, comprising: a) l-30%wt nonionic surfactant, b) 0.005-5%wt of a water soluble, anionic polymer having an average molecular weight less than 1,000,000, wherein, the ratio of polymer:nonionic is 0.1:1 or less. It is believed that an advantage of the compositions of the invention and the method of the invention is that surface damage resulting in either structural weakness or a lack of shine is reduced. Moreover, the compositions of the present invention enable the cleaning effect of the nonionic surfactants to be decoupled from the surface- damaging effects i.e. whereas compositions which clean well have previously been aggressive towards surfaces and compositions which clean poorly less aggressive, the compositions of the invention are both effective cleaners and far less aggressive towards surfaces. Detailed Description of the invention Without wishing to be limited by any theory of operation, it is believed that damage to the plastic surface requires the plastic to be stressed in use or manufacture and the presence of a plasticising agent to weaken the plastic material such that the cracks formed by the stress can propagate. As the cracks lengthen and/or widen the material become structurally weak and the presence of the cracks causes a loss of surface finish. It is believed that, the presence of the polymer either retards the activity of the surfactant as a plasticiser or physically masks the surface to as to reduce access to the cracks. Various preferred and essential features of the invention are described in further detail below. Polymers The water soluble polymer is an essential component of the compositions according to the present invention. Surprisingly, the preferred polymers in embodiments of the present invention are those which are readily available in the marketplace. These are polymers of acrylic or methacrylic acid or maleic anhydride, or a co-polymer of one or more of the same either together or with other monomers. Particularly suitable polymers include polyacrylic acid, polymaleic anhydride and copolymers of either of the aforementioned with ethylene, styrene and methyl vinyl ether. The most preferred polymers are maleic anhydride co¬ polymers, preferably those formed with styrene, acrylic acid, methyl vinyl ether and ethylene. Preferably, the molecular weight of the polymer is at least, 5000, more preferably at least 50,000 and most preferably in excess of 100,000. Typically, the surfactant based cleaning compositions comprise at least 0.01wt% polymer, on product. Unexpectedly, it has been found that the positive benefit of the presence of polymer can be identified even when very low levels of polymer and surfactant are present. This property of a low concentration threshold is particularly advantageous in applications of the invention where considerable dilution is expected. Preferably the level of polymer is 0.05-5.0wt% at which level the anti-resoiling benefits become particularly significant. More preferably 0.2-2.0wt% of polymer is present. We have determined that higher levels of polymer do not give significant further cleaning advantages with common dilution factors, while increasing the cost of compositions. It is believed that high levels of polymer increase the viscosity of the product and hinder product wetting and penetration of the soil. However, for concentrated products which are diluted prior to use, the initial polymer level can be as high as 5%wt. In the context of the present invention, anionic polymers are those which carry a negative charge or similar polymers in protonated form. Mixtures of polymers can be employed. As mentioned above, the molecular weight of the polymer is preferably below 1 000 000 Dalton. It is believed that as the molecular weight increases the cleaning benefit of the polymer is reduced. Surfactants It is essential that compositions according to the present invention comprise at least one nonionic surfactant. The composition according to the invention comprise detergent actives which can be chosen from nonionic detergent actives. Suitable nonionic detergent active compounds can be broadly described as compounds produced by the condensation of alkylene oxide groups, which are hydrophilic in nature, with an organic hydrophobic compound which may be aliphatic or alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield a water-soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements. Particular examples include the condensation product of aliphatic alcohols having from 8 to 22 carbon atoms in either straight or branched chain configuration with 2-15 moles of ethylene oxide. Examples of such materials include a coconut oil ethylene oxide condensate having from 2 to 15 moles of ethylene oxide per mole of coconut alcohol; condensates of alkylphenols whose alkyl group contains from 6 to 12 carbon atoms with 5 to 25 moles of ethylene oxide per mole of alkylphenol; condensates of the reaction product of ethylenediamine and propylene oxide with ethylene oxide, the condensates containing from 40 to 80% of polyoxyethylene radicals by weight and having a molecular weight of from 5,000 to 11,000; tertiary amine oxides of structure R 3 N0, where one group R is an alkyl group of 8 to 18 carbon atoms and the others are each methyl, ethyl or hydroxy-ethyl groups, for instance dimethyldodecylamine oxide; tertiary phosphine oxides of structure R 3 P0, where one group R is an alkyl group of from 10 to 18 carbon atoms, and the others are each alkyl or hydroxyalkyl groups of 1 to 3 carbon atoms, for instance dimethyldodecylphosphine oxide; and dialkyl sulphoxides of structure R 2 S0 where the group R is an alkyl group of from 10 to 18 carbon atoms and the other is methyl or ethyl, for instance methyltetradecyl sulphoxide; fatty acid alkylolamides; alkylene oxide condensates of fatty acid alkylolamides and alkyl mercaptans. The preferred nonionic surfactants are the condensation products of 9-15 carbon alcohols with 3-10 moles of ethylene oxide. The amount of nonionic detergent active to be employed in the composition of the invention will generally be from 1 to 30%wt, preferably from 5 to 20%wt, and most preferably from 12 to 20%wt. Levels of around 15% active are particularly preferred as little increase in neat-use cleaning performance is found at higher levels, although such higher levels can be employed in products intended to be considerably diluted prior to use. Optionally, anionic surfactant can be present in relatively small proportions. Suitable anionic detergent active compounds are water- soluble salts of organic sulphuric reaction products having in the molecular structure an alkyl radical containing from 8 to 22 carbon atoms, and a radical chosen from sulphonic acid or sulphur acid ester radicals and mixtures thereof. Examples of anionic detergents are sodium and potassium alcohol sulphates, especially those obtained by sulphating the higher alcohols produced by reducing the glycerides of tallow or coconut oil; sodium and potassium alkyl benzene sulphonates such as those in which the alkyl group contains from 9 to 15 carbon atoms; sodium and potassium secondary alkanesulphonates; sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid monoglyceride sulphates; sodium and potassium salts of sulphuric acid esters of the reaction product of one mole of a higher fatty alcohol and from 1 to 6 moles of ethylene oxide; sodium and potassium salts of alkyl phenol ethylene oxide ether sulphate with from 1 to 8 units of ethylene oxide molecule and in which the alkyl radicals contain from 4 to 14 carbon atoms; the reaction product of fatty acids esterified with isethionic acid and neutralised with sodium hydroxide where, for example, the fatty acids are derived from coconut oil and mixtures thereof. The preferred water-soluble synthetic anionic detergent active compounds are the ammonium and substituted ammonium (such as mono, di and triethanolamine), alkali metal (such as sodium and potassium) and alkaline earth metal (such as calcium and magnesium) salts of higher alkyl benzene sulphonates and mixtures with olefinsulphonates and higher alkyl sulphates, and the higher fatty acid monoglyceride sulphates. The most preferred anionic detergent active compounds are higher alkyl aromatic sulphonates such as higher alkyl benzene sulphonates containing from 6 to 20 carbon atoms in the alkyl group in a straight or branched chain, particular examples of which are sodium salts of higher alkyl benzene sulphonates or of higher-alkyl toluene, xylene or phenol sulphonates, alkyl naphthalene sulphonates, ammonium diamyl naphthalene sulphonate, and sodium dinonyl naphthalene sulphonate. The amount of synthetic anionic detergent active to be employed in the detergent composition of this invention will generally be from 0.5 to 50%wt (on total active), preferably less than 33%wt (on total active) . For products containing around 15%wt of surfactant, the level of anionic surfactant should preferably not exceed 5%wt on product. It is also possible optionally to include amphoteric, cationic or zwitterionic detergent actives in the compositions according to the invention. Suitable amphoteric detergent-active compounds that optionally can be employed are derivatives of aliphatic secondary and tertiary amines containing an alkyl group of 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water-solubilising group, for instance sodium 3-dodecylamino-propionate, sodium 3-dodecylaminopropane sulphonate and sodium N-2-hydroxydodecyl-N-methyltaurate. Suitable cationic detergent-active compounds are quaternary ammonium salts having an aliphatic radical of from 8 to 18 carbon atoms, for instance cetyltrimethyl ammonium bromide. Suitable zwitterionic detergent-active compounds that optionally can be employed are derivatives of aliphatic quaternary ammonium, sulphonium and phosphonium compounds having an aliphatic radical of from 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water- solubilising group, for instance 3- (N,N-dimethyl-N- hexadecylammonium)propane-1-sulphonate betaine, 3- (dodecyImethyl sulphonium) propane-1-sulphonate betaine and 3- (cetylmethylphosphonium) ethane sulphonate betaine. Further examples of suitable detergent-active compounds are compounds commonly used as surface-active agents given in the well-known textbooks "Surface Active Agents", Volume I by Schwartz and Perry and "Surface Active Agents and Detergents", Volume II by Schwartz, Perry and Berch. The total amount of detergent active compound to be employed in the detergent composition of the invention will generally be from 1.5 to 30%, preferably from 2 to 20% by weight, most preferably from 5-20wt%. solvents It is preferred that the compositions of the present invention comprise not more than 2%wt of solvents of the general formula: R 1 -0-(E0) m -(PO) n -R 2 , wherein R. and R 2 are independently C2-6 alkyl or H, but not both hydrogen, m and n are independently 0-5. It is believed that the use of polymers as in the compositions of the present invention can offset the deleterious effects of any solvent which is present. More preferably, no more than 2%wt of solvent selected from the group comprising di-ethylene glycol mono n-butyl ether, ono-ethylene glycol mono n-butyl ether, propylene glycol n-butyl ether and mixtures thereof is present. Advantageously, effectively no solvent other than water is present . Minors The composition according to the invention can contain other ingredients which aid in their cleaning performance. For example, the composition can contain detergent builders other than the special water-soluble salts, as defined herein, such as nitrilotriacetates, polycarboxylates, citrates, dicarboxylic acids, water-soluble phosphates especially polyphosphates, mixtures of ortho- and pyrophosphate, zeolites and mixtures thereof. Such builders can additionally function as abrasives if present in an amount in excess of their solubility in water as explained herein. In general, the builder, other than the special water-soluble salts when employed, preferably will form from 0.1 to 25% by weight of the composition. Metal ion sequestrants such as ethylenediaminetetraacetates, amino-polyphosphonates (DEQUEST R ) and phosphates and a wide variety of other poly¬ functional organic acids and salts, can also optionally be employed. A further optional ingredient for compositions according to the invention is a suds regulating material, which can be employed in compositions according to the invention which have a tendency to produce excessive suds in use. One example of a suds regulating material is soap. Soaps are salts of fatty acids and include alkali metal soaps such as the sodium, potassium, ammonium and alkanol ammonium salts of higher fatty acids containing from about 8 to about 24 carbon atoms, and preferably from about 10 to about 20 carbon atoms. Particularly useful are the sodium and potassium and mono-, di- and triethanolamine salts of the mixtures of fatty acids derived from coconut oil and ground nut oil. When employed, the amount of soap can form at least 0.005%, preferably 0.5% to 2% by weight of the composition. A further example of a suds regulating material is an organic solvent, hydrophobic silica and a silicone oil or hydrocarbons. Compositions according to the invention can also contain, in addition to the ingredients already mentioned, various other optional ingredients such as pH regulants, colourants, optical brighteners, soil suspending agents, detersive enzymes, compatible bleaching agents, gel-control agents, freeze-thaw stabilisers, bactericides, preservatives, detergent hydrotropes perfumes and opacifiers. It is preferable that the compositions of the present invention are essentially free of abrasive particles. Experiments have shown that the presence of abrasive reduces the cleaning benefit due to the polymer although abrasive would in itself provide a separate cleaning benefit. It is believed that the abrasive, surfactant and polymer form a complex which reduces the effective concentration of the surfactant at the surface being cleaned. As mentioned above, the pH of the compositions according to the present invention is acidic or neutral. We have determined that improved cleaning and/or anti-resoiling benefit is obtained at these pH' s. The preferred pH of the products is 3-7 with a pH in the range 3-6 being more preferred and a pH of 4-6 being particularly preferred so as to provide a balance between the hazards of acid compositions and the advantages of acids for removing limescale. Particularly preferred compositions according to the present invention are mobile aqueous liquids, having a pH of 3-6 which comprise: a) 5-20%wt of a alkoxylated alcohol, nonionic surfactant, b) less than 3%wt of anionic surfactants, c) 0.2-2%wt of a water soluble, anionic polymer having an average molecular weight less than 1,000,000, said polymer being a polymer of at least one of acrylic acid, methacrylic acid or maleic anhydride, with at least one of acrylic acid, methacrylic acid, maleic anhydride, ethylene, styrene and methyl vinyl ether, and , d) not more than 2% of a solvent selected from the group comprising di-ethylene glycol mono n-butyl ether, ono-ethylene glycol mono n-butyl ether, propylene glycol n-butyl ether and mixtures thereof. In order that the present invention may be further understood it will be described hereafter by way of example. EXAMPLES The following examples were obtained using a method which is similar to that of an industry standard in which a 24 hour contact time is used. The shorter (lhr) contact time was used to better distinguish between samples. Strips of clear Perspex (TM) of thickness 3mm, length 127mm and width 12.7mm were cut from a sheet with a bandsaw. Each strip was placed in a bending jig under a flexural strain of 1.75% (equivalent to 40 mega Pascals) . While still in the jig, the strips were contacted with test solutions of nonionic surfactant plus additives as described below for one hour. The liquid under test was placed in a clean 12cm σlass petri dish or other suitable shallow container and the bending jigs inverted over them. The jigs were stably supported 1.5-2cm above bench level, in such a way as the apex of the bent plastic came into good contact with the test medium. Contact time for the 1.75% flexural strain bending jigs (116mm separation between grooves in the jig) is 1 hour at 25°C. After one hour, the strips were rinsed in demineralised water, removed from the jig and carefully wiped dry so as avoid scratching. Care should be taken at this stage as the edges of the perspex are sufficiently sharp to cause shallow cuts if uncovered fingers are slid along their edges and may spring out of the jig. The strips were inspected by placing them on an overhead projector and looking for cracks in the image displayed. The extent of cracking was assessed by a panel of assessors on a scale of 0-20, with 1 representing no damage and 20 representing extreme damage. Damage is assessed on a 20 point scale where: 0 = No damage visible at all 1 = V. slight damage, just resolvable with the naked eye 2 = Slight damage 3 = Significant damage, though some intact surface in contact zone. 4 = Full width of strips with cracks, some small and hard to see. 5 = Full width stress cracks which are clearly visible Scores of 6-20 are assessed by taping 4 strips together and assessing light transmission (eg. on an overhead projector) against a set of pre-defined standards. A panel of assessors were used and results were averaged. In the experiments described, the solvent used was Butyl Digol (TM, ex BDH) which predominantly comprises di¬ ethylene glycol mono-n-butyl ether. The solvent, when present was present at a level of 5%wt on composition. The surfactants used were: Dobanol 91/8: C8-11 alcohol condensed with 8 moles of ethylene oxide. Dobanol 23/6.5 C12-13 alcohol condensed with 6.5 moles of ethylene oxide. Dobanol 91/5 C9-11 alcohol condensed with 5 moles of ethylene oxide. Lial 111/5.5 ClO-11 alcohol condensed with 5.5 moles of ethylene oxide. Dobanol is trademark of Shell. Lial is a trademark of Enichem. The surfactant was present at a level of 10%wt on produc . The perfume used was Opalina (TM ex. Firmenich ) . The polymer used was Versiocol Ell (TM ex. Allied Colloids ) . The polymer, when present, was at a level of 0.5 wt%. Polymer containing samples also contained 2wt% citric acid. Compositions were made up to 100wt% with water. All %'s are given as %wt on product . The results obtained are presented in table 1 below, each composition (base, with solvent and with polymer) being prepared both with and without polymer and with one of four different surfactants. In column (A) for example the four samples with which the strips were treated comprised 10%wt surfactant (identity as indicated), 0.5%wt polymer and 5%wt solvent. The results given in columns B, D and F are those of comparative examples. From Table 1 it can be seen that surface damage is significantly reduced in the presence of the polymer both in the presence (compare column A with column B) and absence (compare column C with column D and column E with column F) of solvent . It can be seen that in the absence of solvent and the presence of polymer (columns C and E) the extent of surface damage was less than that in the control experiment with the nonionic surfactants only (columns D and F) . Examples of the preferred compositions are shown in column C. These comprise nonionic surfactant, perfume and polymer but no solvent . The results of some further experiments are shown below in Table 2. In the experiments represented in table 2 results were obtained by the method given above with (Column B) and without (Column A) the addition of 2% VERSICOL Ell and 2% citric acid. In table 2 the materials used were as noted above, the solvent was BUTYL DIGOL and the perfume was OPALINA. Table 2 Surfactant Additives Damage Damage Score: A Score: B Dobanol 91-5 none 4 1 Dobanol 91-5 5% Digol 17 9.5 Dobanol 91-5 5% Digol + 19.5 16.25 .5%perfume Dobanol 91-5 0.5% perfume 10 2.5 Dobanol 91-8 none 5.5 1 Dobanol 91-8 5% Digol 15 7.5 Dobanol 91-8 5% Digol + 15 8 .5%perfume Dobanol 91-8 0.5% perfume 5 0.5 Dobanol none 0 0 23/6.5 Dobanol 5% Digol 18.25 7.5 23/6.5 Dobanol 5% Digol + 16.5 19.5 23/6.5 .5%perfume Dobanol 0.5% perfume 2 1 23/6.5 Lial 111/5.5 none 7.5 1.25 Lial 111/5.5 5% Digol 20 2.5 Lial 111/5.5 5% Digol + 19.25 13.0 .5%perfume Lial 111/5.5 0.5% perfume 7.5 2.5 From the results in table 2 it can be seen that almost all of the systems tested showed a marked reduction in surface damage when the polymer was added to the composition. Surface damage is seen to be particular bad in the presence of both perfume and solvent.

Claims: CLAIMS 1. The use, in a plastics cleaning composition comprising nonionic surfactant, of a water soluble anionic polymer as an agent to retard the propagation of surface cracks. 2. Use of a water soluble anionic polymer according to claim 1 in a plastics cleaning composition which is essentially free of solvents selected from the group comprising di-ethylene glycol mono n-butyl ether, mono-ethylene glycol mono n-butyl ether, propylene glycol n-butyl ether and mixtures thereof. 3. Use of a water soluble anionic polymer according to claim 1 wherein the water soluble anionic polymer is acrylic or methacrylic acid or maleic anhydride, or a co-polymer of one or more of the same either together or with other monomers. 4. Use of a water soluble anionic polymer according to claim 1 wherein the composition comprises: a) 5-20%wt of a 9-15 carbon 3-10 mole-equivalent alkoxylated alcohol, nonionic surfactant, b) less than 3%wt of anionic surfactants, c) 0.2-2%wt of a water soluble, anionic polymer having an average molecular weight less than 1,000,000, said polymer being a polymer of at least one of acrylic acid, methacrylic acid or maleic anhydride, with at least one of acrylic acid, methacrylic acid, maleic anhydride, ethylene, styrene and methyl vinyl ether, d) not more than 2% of a solvent selected from the group comprising di-ethylene glycol mono n-butyl ether, mono-ethylene glycol mono n-butyl ether, propylene glycol n-butyl ether and mixtures thereof. 5. A method for cleaning plastics surfaces which comprises the step of treating the surface with a cleaning composition of pH 2-10, comprising: a) l-30%wt nonionic surfactant, b) 0.005-5%wt of a water soluble, anionic polymer having an average molecular weight less than 1,000,000, wherein, the ratio of polymer:nonionic is 0.1:1 or less. 6. A method according to claim 5 wherein the anionic polymer comprises acrylic or methacrylic acid or maleic anhydride, or a co-polymer of one or more of the same either together or with other monomers. 7. A method according to claim 5 wherein the nonionic surfactant comprises a 9-15 carbon 3-10 mole- equivalent alkoxylated alcohol, nonionic surfactant. 8. A method for cleaning plastics surfaces which comprises the step of treating the surface with a composition comprising: a) 5-20%wt of a 9-15 carbon 3-10 mole-equivalent alkoxylated alcohol, nonionic surfactant, b) less than 3%wt of anionic surfactants, c) 0.2-2%wt of a water soluble, anionic polymer having an average molecular weight less than 1,000,000, said polymer being a polymer of at least one of acrylic acid, methacrylic acid or maleic anhydride, with at least one of acrylic acid, methacrylic acid, maleic anhydride, ethylene, styrene and methyl vinyl ether, d) not more than 2% of a solvent selected from the group comprising di-ethylene glycol mono n-butyl ether, mono-ethylene glycol mono n-butyl ether, propylene glycol n-butyl ether and mixtures thereof.

Inventors: LEACH MATTHEW JAMES, NEWBOLD GEOFFREY, SHARPLES MARTIN, TURNER JANE ELIZABETH, LEACH, MATTHEW, JAMES, NEWBOLD, GEOFFREY, SHARPLES, MARTIN, TURNER, JANE, ELIZABETH
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1996
Main classification: C11D3
IPC codes: C11D1, C11D3, C11D11