WO1998059029A1

WO1998059029A1 - Process for treatment of surfaces

Info

Publication number: WO1998059029A1
Application number: PCT/EP1998/004011
Authority: WO
Inventors: Ana Claudia Marquezano Medeiros; Robert Jan Reinier Uhlhorn
Original assignee: Unilever Plc; Unilever N.V.
Priority date: 1997-06-23
Filing date: 1998-06-16
Publication date: 1998-12-30
Also published as: AU8853598A; GB9713255D0; BR9705010A

Abstract

A process for removing and preventing the regrowth of mold on a hard surface which comprises the step of contacting the surface with a composition comprising: a) 2-10 wt.% of an alkali metal hypohalite, b) 0.25-5 wt.% of an amine oxide, and c) 0.25-5 wt.% of a surfactant selected from the group comprising an disulphonated diphenyl oxide anionic surfactant or a quaternary ammonium cationic surfactant.

Description

PROCESS FOR TREATMENT OF SURFACES

Technical Field

The present invention relates to a process for treating surfaces so as to remove mold and prevent or retard the re- growth of the mold.

Background of the Invention

Molds, such as Penicillium and Aspergillus are common in damp environments such as kitchens and bathrooms. They are particularly prone to grow on the grouting of tiles and around ventilator grilles and ducts. The removal of molds presents two problems, first the mold must be killed and its-regrowth prevented and second the pigments which are produced by the mold, and which are typically dark in colour, must be bleached or removed.

Hypohalites are well-known as hygiene and/or bleaching components in surfactant containing cleaning compositions. Typically, these compositions have an alkaline pH. It is known that hypohalites, particularly alkali metal hypo-chlorites, are effective against molds both in terms of killing the mold and bleaching the mold pigments.

In order to assist in the removal of soils, it is desirable that cleaning compositions should contain surfactant, however, not all surfactants are stable in the presence of hypochlorites . Three groups of surfactants which are known to be stable in the presence of hypochlorites are the nonionic amine oxides, cationic quaternary ammonium salts and the alkylated disulphonated diphenyl oxides. Hypohalites are very reactive hygiene agents and consequently have a short shelf life. It is known that the shelf life of products can be improved by the use of the alkylated disulphonated diphenyl oxides .

While sodium hypochlorite has been used effectively to kill molds and bleach their pigments, a problem which remains outstanding is that antimicrobial properties of hypohalites are rapidly lost after application to a surface. Consequently, there remains a need to deliver a longer-lasting hygiene effect.

Brief Description of the Invention

We have now determined that longer-lasting mold removal by alkaline hypohalite cleaning compositions is obtained if a combination of surfactants is used in said compositions, in particular if a nonionic amine oxide surfactant is used together with an disulphonated diphenyl oxide anionic surfactant or a quaternary ammonium cationic surfactant.

Detailed Description of the Invention

Accordingly a first aspect of the present invention provides a process for treating a mold-infected hard surface which comprises the step of contacting the surface with a composition comprising: a) 2-10%wt of an alkali metal hypohalite b) 0.25-5%wt of an amine oxide, and, c) 0.25-5%wt of a surfactant selected from the group comprising disulphonated diphenyl oxide anionic surfactants and quaternary ammonium cationic surfactants. It is believed that this combination of components not only removes the mold from the surface, but has an unexpected benefit in retarding the re-growth of mold on the treated surface.

Typically, compositions according to the invention comprise 3- 7%wt of an alkali metal hypohalite, preferably hypo-chlorite, more preferably sodium hypochlorite. Preferred embodiments of the invention comprise 4-5%wt of the hypochlorite.

Typically, compositions according to the invention comprise 0.5-2%wt of amine oxide, more preferably about l%wt.

Preferred are tertiary amine oxides of structure R₃N0 , where one group R is an alkyl group of 8-18 carbon atoms and the others are each methyl, ethyl or hydroxy-ethyl groups, for instance dimethyldodecylamine oxide. Amine oxides with a carbon chain length of C8-C14 are particularly preferred.

Where disulphonated diphenyl oxide anionic surfactants are used these are preferably alkylated. Materials with a C12 or longer alkyl group are preferred. A particularly suitable material is DOWFAX 8360 (TM: ex DOW) . Typically compositions according to the invention comprise 0.5-2%wt of the disulphonated diphenyl oxide, more preferably about 0.7-l%wt.

Suitable quaternary ammonium cationic surfactant materials

+ - include materials of the general formula R₁R₂R₃R₄N X , wherein all of the radicals are hydrocarbons with or without hydroxy substitution, at least one of the radicals ₁-R₄ is a C6-C22 alkyl, alkaryl or hydroxyalkyl, at least one of the radicals

R₁-R₄ is a C1-C4 alkyl or hydroxy alkyl and X is a monovalent anion equivalent . Preferably R_± and R₂ are the same or different C1-C4 alkyl or hydroxy alkyl, R₃ is a C6-C22 alkyl, alkaryl or hydroxyalkyl, R₄ is a C1-C22 alkyl, alkaryl or hydroxyalkyl and X is a monovalent anion equivalent.

Preferably X is a halogen, most preferably chloride or bromide .

Preferably R_χ and R₂ are methyl. In embodiments of the invention R₃ is preferably C8-C18 alkyl, more preferably C10-

C16 alkyl. In embodiments of the invention R₄ is preferably methyl, C8-C18 alkyl or benzyl. Thus, the cationic surfactants used can have three 'short chain¹ radicals, such as methyl, and one fatty-soluble Aong chain' radical or two 'short' chains and two fatty-soluble 'long chains', wherein the ' long chains ' can be either linear or branched hydrocarbons or contain aromatic rings.

Particularly suitable cationic detergent-active compounds include cetyltrimethyl ammonium bromide (CTAB) , hardened di- tallow di-methyl ammonium chloride and benzalkonium chloride. The cationic surfactants which comprise one aryl substituent are especially preferred as they are believed to give particularly good antimicrobial effects.

Typically compositions according to the invention comprise 0.5-2%wt of quaternary ammonium cationic surfactant, more preferably about l%wt.

Compositions according to the present invention are preferably strongly alkaline. It is preferred that compositions according to the invention comprise at least 0.5%wt of a strong alkali, such as an alkali metal hydroxide, preferably sodium hydroxide. It is preferable that the pH of the compositions of the invention is above 11 as this improves the stability of the compositions to phase separation. Typical products according to the invention will comprise perfume at levels of less than 0.1%wt.

Minor components include stabilisers for the hypohalites such as periodates and/or silicates. Typical levels of silicate are 0.01-0.1%wt. Other stabilisers for hypochlorite, such as are known in the art, can be included in compositions according to the invention.

Preferred compositions for embodiments of the invention are:

a) Sodium hypochlorite 4-5 %wt b) Sodium hydroxide 0.5-1.5 %wt c) Amine oxide 0.5-2 %wt d) Charged surfactant 0.5-2 %wt e) Sodium silicate 0.01-0.1%wt f) Perfume 0.01-0.1%wt

In order that the invention may be further understood it will be described with reference to the following non-limiting examples .

Examples :

Compositions A and B were made up according to Table 1 below:

Table 1; Compositions

These composition were tested on gypsum plates which had been infected with either Aspergillus niger (ATCC 16404) or Penicillium ci trium (ATCC 9848) .

Cultures were maintained on nutrient agar slopes (ex DIFCO) for at least 7 days prior to inoculation. Spores were resuspended in 10ml sterile NaCl (0.9%) and serially diluted (1:9) to obtain a final spore concentration of around 1000000 spores/ml. Counts were obtained by mixing 1 ml of inoculum in each petri dish used together with 30ml of culture medium.

The same process was used to obtain cultures on agar for the growth experiments described below.

Products were sprayed onto the gypsum plates using a uniform spraying protocol (2g of product) and controls were carrying out a similar process using a commercial mold removing product ^■X-14' (TM: ex Stafford Miller, Brazil) or ' Pato Limpa Li o' (TM: ex Ceras Johnson, Brazil) . Sprayed plates were allowed to dry, laid on inoculated nutrient agar and incubated for 21 days at 26 Celcius.

Results for mold growth after 21 days are shown below (Table 2 ) in terms of the area of the plates which had been covered by the mold.

Table 2; %area growth of mold on gypsum after 21 days

From these results it can be seen that the process according to the present invention is more successful that the controls at retarding the growth of mold. Untreated plates showed full mold coverage after three weeks . The two examples of the invention showed no growth of P. citrium over the time-course of the experiment and the reduction in the regrowth of the A . niger was markedly better than that of the comparative products. It can be seen that the composition 'A' based on the combination of amine oxide and the disulphonated diphenyl oxide anionic surfactant gave slightly better results than 'B' .

Claims

1. A process for treating a mold-infected hard surface which comprises the step of contacting the surface with a composition comprising: a) 2-10%wt of an alkali metal hypohalite, b) 0.25-5%wt of an amine oxide, and, c) 0.25-5%wt of a surfactant selected from the group comprising disulphonated diphenyl oxide anionic surfactants or quaternary ammonium cationic surfactants .

2. Process according to claim 1 wherein the disulphonated diphenyl oxide anionic surfactant is an alkylated disulphonated diphenyl oxide anionic surfactant.

3. Process according to claim 1 wherein the quaternary nitrogen compound is of the general formula R₁R₂R₃R₄N⁺XJ where R_╧ç and R₂ are the same or different C1-C4 alkyl or hydroxy alkyl, R₃ is a C6-C22 alkyl, alkaryl or hydroxyalkyl, R₄ is a C1-C22 alkyl, alkaryl or hydroxyalkyl and X is a monovalent anion equivalent.