WO2004074417A1

WO2004074417A1 - Antimicrobial cleaning compositions

Info

Publication number: WO2004074417A1
Application number: PCT/EP2004/001014
Authority: WO
Inventors: Stefano Giolito; Gianluca Lucchini
Original assignee: Unilever Plc; Unilever Nv; Hindustan Lever Limited
Priority date: 2003-02-24
Filing date: 2004-02-03
Publication date: 2004-09-02

Abstract

The invention provides an aqueous acidic antimicrobial cleaning composition suitable for the hygienic cleaning of surfaces, which composition comprises an acid, an amine oxide surfactant, and an N-alkylpyrrolidone derivative. Compositions of the invention are designed in particular for the hygienic cleaning of hard surfaces, and are preferably supplied in the form of wipes, in which a disposable substrate (such as a porous or absorbant sheet or cloth) has been pre-treated with the composition into or onto the substrate prior to its use by the consumer.

Description

ANTIMICROBIAL CLEANING COMPOSITIONS

Technical Field

The present invention relates to an aqueous antimicrobial cleaning composition which is designed in particular for the hygienic cleaning of surfaces, such as hard surfaces in the household. The composition contains an antimicrobially active mixture of acid, amine oxide surfactant and N- alkylpyrrolidone derivative.

Background to the Invention and Prior Art

Hard surfaces in the household, are often contaminated with bacteria and other micro-organisms, which present a risk to human health, especially when they are present near food.

Antimicrobial compositions based o quaternary ammonium cationic surfactants such as benzalkonium chloride are widely used. However, a disadvantage of such compositions is that they tend to leave residues behind after use. This necessitates a rinsing step which is undesirable for the consumer .

EP 0 948 892 describes a liquid disinfectant for hard surfaces in which reduced filming or streaking is observed due, it is said, to the presence of a poly (alkylene glycol) alkyl ether. Organic solvents such as ethanol , butyl carbitol and n-butoxypropanol are also included to enhance cleaning. W098/55569 and O98/55570 relate to aqueous hard surface cleaners with improved residue removal and reduced filming/streaking. The compositions comprise a mixture of anionic surfactants, an organic solvent such as an alkylene glycol ether, and preferably include a 1-alkyl-2 -pyrrolidone for dispersal of fragrance oils and other insoluble organic materials in the compositions. The compositions are buffered to pH greater than 6.5 with a nitrogenous buffer.

A problem with the above proposals is that the formulations are required to contain a significant amount of volatile organic compounds as solvents. Environmental and flammability concerns have prompted research into reducing the level of volatile organic compounds in consumer products. The problem then arises that adding other ingredients to compensate for the reduced alcohol content is associated with a "streak" effect on the surface once the liquid dries due to residues left behind. Antimicrobial performance may also be compromised.

The present inventors have found that cleaning compositions comprising acid, amine oxide surfactant and N- alkylpyrrolidone derivative show not only excellent cleaning but also superior "end-results" (i.e. no significant residues, streaks or spotting left behind after use) .

Surprisingly, these properties are apparent even at low levels of active ingredient and with little or no organic solvent present .

Compositions of this invention also possess antimicrobial activity and are particularly suited for the hygienic cleaning of surfaces such as hard surfaces in the household. The compositions provide the requisite level of bacterial kill for this type of application without requiring the addition of any further antibacterial actives. This is surprising since none of the individual components in themselves possess any significant biocidal activity when used singly.

Summary of the Invention

The present invention provides an aqueous acidic antimicrobial cleaning composition suitable for the hygienic cleaning of surfaces, which composition comprises an acid, an amine oxide surfactant, and an N-alkylpyrrolidone derivative.

Detailed Description of the Invention

Acid

Compositions of the invention contain an acid which is preferably organic in nature.

Suitable organic acids for use herein include organic carboxylic acids and mixtures thereof.

The organic carboxylic acids and mixtures thereof may suitably be selected from aliphatic, cycloaliphatic or aromatic mono-, di- , tri- or polycarboxylic acids which generally contain 2 to 10 carbon atoms, preferably 3 to 6 carbon atoms in the molecule. Hydroxycarboxylic acids may also be used.

Examples of suitable organic carboxylic acids include citric acid, picolinic acid, caprylic acid, propionic acid, azelaic acid, caproic acid, hydroxybenzoic acid, salicylic acid, malic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, tartaric acid and mixtures thereof .

Citric acid is especially preferred.

The level of acid in compositions of the invention suitably ranges from 0.05 to 2%, preferably from 0.1 to 1%, more preferably from 0.3 to 0.8% by total weight of acid based on total weight of the composition.

Amine oxide surfactant

Suitable amine oxides to be used in the composition of the invention may be generally described as those tertiary amine oxides of the formula R^R'NO, in which each R is a lower alkyl group, for instance an alkyl group having from 1 to 3 carbon atoms, preferably methyl, and R' is a long chain alkyl group, for instance an alkyl group having from 8 to 24 carbon atoms, preferably from 8 to 18 carbon atoms, more preferably from 12 to 18 carbon atoms.

The level of amine oxide in compositions of the invention suitably ranges from 0.05 to 3%, preferably from 0.1 to 1.5%, more preferably from 0.3 to 0.8% by total weight of amine oxide based on total weight of the composition.

N-alkylpyrrolidone derivative

Compositions of this invention contain an N-alkylpyrrolidone derivative .

Suitable N-alkyl pyrrolidone derivatives are N- (n-alkyl) pyrrolidones where the alkyl group has from 6 to 20, preferably from 8 to 14 carbon atoms.

Preferred N-alkyl pyrrolidone derivatives are N- (n-octyl) -2 - pyrrolidone, N- (n-decyl) -2 -pyrrolidone, N- (n-dodecyl) -2- pyrrolidone and N- (n-tetradecyl) -2 -pyrrolidone .

Particularly preferred is N- (n-octyl) -2 -pyrrolidone, available commercially as SURFADONE LP-100 ex International Speciality Products, Inc.

The level of N-alkyl pyrrolidone derivative in compositions of the invention suitably ranges from 0.05 to 2%, preferably from 0.1 to 1%, more preferably from 0.3 to 0.8% by total weight of N-alkyl 'pyrrolidone derivative based on total weight of the composition.

Compositions of the invention will generally have a pH from 2.5 to 5.0., preferably from 3.0 to 4.5. The most preferred pH is around 3.8.

A water soluble base such as an alkali metal hydroxide, (typically sodium hydroxide) is generally used to regulate the pH to the required level .

Optional Ingredients

Compositions according to the invention can contain other optional ingredients which aid in their cleaning performance and maintain the physical and chemical stability of the product .

For example, solvents may be present in the compositions of the invention. Suitable solvents are organic solvents corresponding to the general formula R^-O- (EO) _m- (PO) _n-R₂ , wherein R^ and R₂ are independently C₂-₆ alkyl or hydrogen, but not both hydrogen, m and n are independently 0-5, EO represents an ethyleneoxy group and PO represents a propyleneoxy group.

Suitable materials of this type include di-ethylene glycol mono n-butyl ether, mono-ethylene glycol mono n-butyl ether, propylene glycol n-butyl ether, isopropanol, ethanol , butanol and mixtures thereof.

Preferably m, n are both 0 and R₂ is hydrogen. Preferably the level of solvent, if present, is less than 5%, more - preferably less than 2.5% by total weight of solvent based on total weight of the composition.

Compositions according to the invention can also contain, in addition to the ingredients already mentioned, other optional ingredients such as chelating or sequestering agents, foam-control agents, colorants, viscosity modifying agents, freeze-thaw stabilisers, additional hygiene agents, perfumes and opacifiers.

For example, hydrogen peroxide may be present in compositions of the invention as an optional additional hygiene agent, at a level of from 0 to 1% by weight based on total weight of the composition.

Suitable sequestering agents which may optionally be present in compositions of the invention, at a level of from 0 to 0.5% by weight based on total weight of the composition, include ethylenediamine tetraacetate, organophosphonic acids and their salts, phosphates and a wide variety of other polyfunctional organic acids and salts. Preferred sequestering agents are organophosphonic acids and their salts, such as those in the DEQUEST® range. Examples include hydroxyethylidene diphosphonic acid (DEQUEST® 2010) , ethylenediamine tetra (methylene-phosphonic acid) (DEQUEST® 2040), diethylene-triamine penta (methylene-phosphonic acid) (DEQUEST® 2060) and their salts. Compositions according to the invention are preferably substantially free from quaternary ammonium cationic surfactants (such as benzalkonium chloride) . By this is meant that compositions of the invention contain no more than 1%, preferably no more than 0.1%, most preferably no more than 0% of quaternary ammonium cationic surfactant (by weight based on total weight of the composition) . Advantageously, the compositions of the invention provide the requisite level of microbial kill for hygienic applications without requiring the inclusion of materials such as quaternary ammonium cationic surfactants.

Product Form and Packaging

Compositions of the invention are aqueous compositions which preferably contain relatively low levels of actives. Typically the principal ingredient is water, which is normally present at a level of at least 50%, preferably at least 80%, more preferably at least 90%, by weight based on total weight. The use of distilled or demineralised water is preferred, but not essential to the invention.

Compositions of the invention are designed in particular for the hygienic cleaning of hard surfaces. By "hard surfaces" is meant those surfaces which are typically found in the household and which are prone to microbial contamination. Examples include lavatory fixtures, lavatory appliances (toilets, bidets, shower stalls, bathtubs and bathing appliances) , wall and flooring surfaces and those surfaces associated with kitchen environments and other environments associated with food preparation. Compositions of the invention may suitably be supplied as a ready to use product packaged in a conventional plastics container. Examples of suitable packaging forms include spray dispensers, foam dispensers, toilet cleaner dispensers, and all packaging forms which are adapted to dose the product for use by the consumer.

Most preferably, compositions of the invention may be supplied in the form of wipes. By "wipe" it is meant a disposable substrate (such as a porous or absorbent sheet or cloth) which has been pre-treated with a composition of the invention so as to incorporate the composition of the invention into or onto the substrate prior to its use by the consumer .

This product form is particularly preferred since it allows for safe and convenient one-step hygienic cleaning disinfection of surfaces by the user.

Typically the wipe is formed by absorbing a composition of the present invention onto the substrate to form a moist wipe. A batch of wipes can then be placed in a container which can be opened when needed and when closed, sufficiently seals to prevent evaporation of any components from the composition. The composition of the invention is impregnated at the desired weight onto one or both sides of a substrate which may be formed from any woven or nonwoven fibre, fibre mixture or foam of sufficient wet strength and absorbency to hold an effective amount of the composition. Preferable materials used to form the substrate include in general all nonwoven materials with sufficient liquid absorption capacity to contain the composition of the invention and to deliver it in use.

Illustrative examples of suitable nonwoven materials include fibres from natural sources such as viscose, cellulose, or from synthetic origin such as polypropylene or polyester. Also suitable are mixtures of these materials such as viscose/polyester, viscose/polypropylene, and cellulose/polyester .

The nonwoven materials can be formed into webs using technologies generally known in the nonwovens art such as carding, drylaid, wetlaid, airlaid and extrusion.

Webs can be bonded using technologies known in the nonwovens art such as needlepunch, stitchbond, hydroentangling, chemical bonding, thermal bonding, spunbond, spunlace, airlace and meltblowing.

The substrate may be a single layer structure or a multilayer structure formed from layers of materials of the above general type, which may be the same or different.

Particularly suitable substrates are nonwovens which have at least on one side a textured abrasive surface.

As used herein, the term "textured abrasive surface" refers to a surface texture that enables the wipe to produce a mild scouring or abrading action to effectively break up and remove dirt or other contaminants. Such dirt or contaminants are frequently embedded in a surface.

Most preferably the textured abrasive surface is formed from nodules and/or striations of an abrasive material applied thereon. The abrasive material itself will preferably have a hardness ranging from 40 to 100 Shore D units.

Shore D hardness is measured at 20°C using the procedures explained in ISO R 868. A suitable instrument is the Bareiss HHP 2000 Shore Hardness tester.

Synthetic polymeric abrasive materials are especially useful . Most preferred are those having a hardness ranging from 40 to 100 Shore D units, preferably from 50 to 95 Shore D units, more preferably from 70 to 90 Shore D units.

Suitable synthetic polymeric abrasive materials of the appropriate Shore D hardness range as defined above include polyolefins, polyesters, polyvinyl chlorides, and polyamides . Copolymers or mixtures of any of these may also be suitable. Specific examples include polyethylene, polypropylene, polybutylene, polyethylene terephthalate, poly (ethylene) vinyl acetate, polystyrene, polyamide, polymethyl methacrylate, and polyvinyl chloride.

The nodules and/or striations of abrasive material may be distributed on the wipe substrate in a uniform pattern (such as polka dots) or an irregular distribution (such as speckles or streaks) , depending on the method used to apply the abrasive to the wipe. A uniform pattern is preferred. The abrasive material may be applied to the wipe in a number of different ways known to those skilled in the art.

For example, for melt-blown wipes the abrasive material may be applied directly following extrusion of the fibres used to form the wipe. The abrasive material is then embedded in the molten surface and becomes locked in place as the fibres cool .

For pre-formed wipe webs based on entangled fibres, such as spunlace wipes, the abrasive material is typically held in place on the substrate by means of an adhesive. The adhesive and abrasive material may be applied to the wipe substrate by any suitable method. Roller coating and screen printing both give good results. Alternatively a solution or dispersion of the adhesive containing dispersed abrasive particles may be sprayed onto the wipe substrate and subsequently heat-cured.

If desired, abrasive particles may be formed in situ on the wipe substrate by spraying or sputtering molten or dissolved polymer onto the substrate. Another suitable method is described in W097/21865, according to which an abrasive nonwoven fibrous web material is produced by firstly forming a nonabrasive precursor web of nonwoven fibrous material. The precursor web carries on one surface a uniform distribution of attenuated meltable thermoplastic fibres, such as polypropylene fibres. The precursor web is then heated sufficiently to cause the attenuated thermoplastic fibres to shrink and form nodulated fibre remnants that impart a roughened abrasive character to the planar surface of the resultant web material . Because the fibres nodulate in situ, after being integrated within the web, this permits the formation of a single layer structure.

A commercially available example of a suitable material used to form the substrate is Tecnofibra T10, from Tecnofibra (Italy) .

In a wipe according to the invention, the weight ratio of composition of the invention to substrate suitably ranges from 1:1 to 6:1, and is preferably from 1:1 to 4:1, more preferably from 2:1 to 3:1.

The invention will now be illustrated by the following non- limiting Examples, in which all percentages are by weight based on total weight, unless otherwise indicated.

EXAMPLES

Examples 1 and 2

Examples 1 and 2 having ingredients as shown in the following Table illustrate formulations according to the invention:

Performance Evaluation

Disinfection

The disinfecting properties of the formulations of Examples

1 and 2 were measured by evaluating their bactericidal activity according to the methodology described in European standard EN 1276. This specifies a test method and requirements for the minimum bactericidal activity of a disinfecting composition. The formulations of Examples 1 and

2 pass this test at high soil with 5 minutes contact time, and at 33% dilution, giving at least log 5 kill against all four test bacterial strains Pseudomonas aeruginosa, Escherichia coli , Staphylococcus aureus and Enterococcus hirae .

Comparative formulations corresponding to the formulation of Example 1, but omitting one or more of the amine oxide, N- (n-octyl) -2 -pyrrolidone and citric acid ingredients were also tested. None of these comparative formulations passed the test described above under the conditions described above .

Cleaning

The formulation of Example 1 was used to form an abrasive wipe by impregnating a substrate having an abrasive surface (Tecnofibra T10, ex Tecnofibra, Italy) with the formulation at a formulation: substrate weight ratio of 2:1. The abrasive wipe so formed was evaluated for its cleaning performance against a variety of typical kitchen and bathroom soils. Its streaks profile (i.e. any residues left behind after treatment of a surface with the wipe) was also measured using black ceramic and stainless steel tiles.

The results showed excellent overall cleaning performance and a significantly improved streaks profile when compared in the same test with existing commercially available premium abrasive wipe products: ST.MARC Degraisse'Nette, ex Reckitt Benckiser; GIF^® Double Action, ex Lever Faberge. In the above comparative products, cationic surfactant and anionic surfactant respectively are used as the primary surfactant component instead of amine oxide .

Claims

1. An aqueous acidic antimicrobial cleaning composition suitable for the hygienic cleaning of surfaces, which composition comprises an acid, an amine oxide surfactant, and an N-alkylpyrrolidone derivative.

2. A composition according to claim 1, in which the acid is an organic carboxylic acid.

3. A composition according to claim 1 or 2 , in which the amine oxide surfactant is a tertiary amine oxide of the formula R₂R'N0, in which each R is a lower alkyl group having from 1 to 3 carbon atoms, and R' is a long chain alkyl group having from 8 to 24 carbon atoms.

4. A composition according to any one of claims 1 to 3 , in which the N-alkyl pyrrolidone derivative is an N- (n-alkyl) pyrrolidone where the alkyl group has from 8 to 14 carbon atoms.

5. A composition according to any one of claims 1 to 4, which has a pH from 3.0 to 4.5.

6. A composition according to any one of claims 1 to 5, which comprises from 0 to 2.5% of an organic solvent corresponding to the general formula R_]_-0- (EO) _m- (PO) _n-R2 , wherein R]_ and R2 are independently C₂-₆ alkyl or hydrogen, but not both hydrogen, m and n are independently 0-5, EO represents an ethyleneoxy group and PO represents a propyleneoxy group, by total weight of organic solvent based on total weight of the composition.

7. A wipe suitable for the hygienic cleaning of surfaces which is formed by absorbing a composition according to any one of claims 1 to 6 onto a disposable substrate.

8. A wipe according to claim 7, in which the substrate is a nonwoven which has at least on one side a textured abrasive surface formed from nodules and/or striations of an abrasive material applied thereon.