NZ206355A - Non-corrosive detergent composition containing silica - Google Patents

Abstract

The invention pertains to aqueous liquid detergent compositions having improved non-corrosive properties which comprise an effective amount of silica having a surface area greater than 200 m<2>/gram. The inclusion of silica provides good non-corrosive properties both in respect to metal and enamel surfaces.

Description

New Zealand Paient Spedficaiion for Paient Number £06355 2 0 C5 s Priority Date(s): .U. .£/?.

Complete Specification Filed: Class: \)4* Publication Date: ...11.1 .1^.? P.O. Journal. No: j9*3p? NEW ZEALAND O (\ ' ^ 1 S ? S/y PATENTS ACT, 1953 I „ 22 NOV f9jJ3 %< yv No.: Date: COMPLETE SPECIFICATION LIQUID DETERGENT COMPOSITIONS i/We, UNILEVER PLC a company organised under the laws of Great Britain, Unilever House, Blackfriars, London E.C.4, England hereby declare the invention for which K/ we pray that a patent may be granted to xa&c/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - - 1 - (followed by page la) C 816 (R) 6 ii * r^y 4-' v> j 5 1Q LIQUID DETBROCWT COHPOGITIOHO The present invention relates to liquid detergent compositions and in particular to aqueous liquid detergent compositions having improved non-corrosive properties.

It is desirable to include an anti-corrosion agent in detergent compositions in order to inhibit the corrosive and discolouring influence of the washing liquid on metal or enamel parts of washing machines and to prevent thereby the malfunctioning of the machines or the discolouring of fabrics which come into contact with such corroded parts.

Aqueous liquid detergent compositions containing corrosion inhibiting agents are known in the art. Generally used are soluble silicates, such as meta-silicate, orthosilicate and sesquisi1icate. Apart from their corrosion inhibiting action, such compounds provide the liquid detergent composition with a highly alkaline environment, which is not always a desirable circumstance, especially if in such compositions alkali-sensitive ingredients are used. Further anti-corrosive agents described in the detergent art include sulphites, nitrites, carbonates, borax or organic compounds such as benzoates.

It has now been found that the corrosive action of aqueous liquid detergent compositions can be reduced to a significant extent by incorporation of silica of such type and in such amount that in the wash liquor a certain threshold concentration of dissolved silica is established.

C 816 (R) 2 063 Accordingly the present invention provides aqueous liquid detergent compositions with improved non-corrosive properties, comprising conventional detergent ingredients and an effective amount of silica of the type to be defined hereafter.

It has been found that in order to achieve optimal anti-corrosion protection the silica must be present in the wash liquor in a dissolved form at a concentration of at least 120 ppm by weight and preferably 150 ppm by weight. According to the present invention therefore, in order to provide the required amount of dissolved silica in the wash liquor to ensure adequate anti-corrosion protection, the silica will in general be incorporated in the liquid detergent composition in an amount which is the equivalent of from about 1% to 10% by weight, preferably from 1.5% to 5% by weight and most preferably from 2% to 4% by weight of the liquid detergent composition which is intended for use at an in-wash product dosage of 10 g/1.

If a liquid detergent composition is formulated having a preferred in-wash product dosage which is different from 10 g/litre, the amount of silica that should be incorporated to achieve adequate anti-corrosion protection must be adjusted accordingly, such that the amount thereof corresponds with the ranges as defined for 10 g/1 product dosage.

The silica to be used in the present invention should have a surface area which is greater than 200 m^ per gram and preferably greater than 350 per gram or even 500 per gram. The upper limit of the surface area is not a critical factor, but normally surface areas range to about 1200 m* per gram.

C 816 (R) 20635; In general such silicas have elementary particle sizes of less than about 30 nm, in particular less than about 25 nm. Preferably, elementary particle sizes are less than 20 nm or even 10 nm. There is no critical lower limit of the elementary particle size; the lower limit is governed by other factors such as the manner of manufacture etc. In general, commercially available silicas have elementary particle sizes of 1 nm or more.

Suitable forms of silica include amorphous silica, such as precipitated silica, pyrogenic silica and silica gels, such as hydrogels, xerogels and aerogels, or the pure crystal forms quartz, tridymite or crystobal-j.te, but the amorphous forms of silica are preferred.

Suitable silicas may readily be obtained commercially. They are sold, for instance, under the Registered Trade Names of Aerosil 380 (ex Degussa Corp., N.J., USA), Cab-O-Sil M5 (ex Cabot Corp., Ill, USA), Tixosil 38A (ex SI Chimie, France) and Gasi.1 200 (ex Crosfield, UK) .

The liquid detergent compositions of the invention further comprise as essential ingredient an active detergent material, which may be an alkali metal or al-kanolamj.ne soap of Cio_c24 fatty acid, including polymerized fatty acids, or an anionic, nonionic, cat-ionic, zwitterionic or amphoteric synthetic detergent material, or a mixture of any of these. The anionic synthetic detergents are synthetic detergents of the sulphate- and sulphonate-types. Examples thereof are salts (including sodium, potassium, ammonium and substituted ammonium salts, such as mono-, di- and tri-ethanolamj.ne salts) of Cg-C2g alkyl benzene sulphon-ates, Cg-C22 primary or secondary alkane sulphonates, <"8~C24 sulphonates, sulphonated polycarboxylic acids, prepared by sulphonation of the pyrolized product C 816 (R) 206355 of alkaline earth metal citrates, e.g. as described j.n British Patent Specifj.cation No. 1 082 179, Cg-C22 al-kyl sulphates, Cg-C24 polyglycol ethersulphates, (containing up to 10 moles of ethylene oxides); further examples are described in "Surface Active Agents and Detergents" (Vol. I and II) by Schwartz, Perry and Berch.

Examples of nonionic synthetic detergents are the condensation products of ethylene oxi.de, propylene oxide and/or butylene oxide with Cg-C^g alkylphenols, Cg-C^g primary or secondary aliphatic alcohols, Cg-C^g fatty acid amides; further examples of nonionics include tertiary amine oxides with one Cq-C18 alkyl chain and two cl~c3 chains. The above reference also describes further examples of nonionics.

The average number of moles of ethylene oxide and/or propylene oxi.de present in the above nonionics varies from 1 to 30; mixtures of various nonionics, including mixtures of nonionics with a higher degree of alkoxyl-ation, may also be used.

Examples of cati.onic detergents are the quaternary ammonium compounds such as alkyl dimethyl ammonium halo-genides .

Examples of amphoteric or zwitterionic detergents are N-alkylamino acids, sulphobetaines and condensation products of fatty acids with protein hydrolysates, but owing to their relatively high cost they are usually used in combination with an anionic or a nonionic detergent. Mixtures of the various types of active detergents may also be used, and preference is given to mixtures of an anionic and a nonionic detergent-active compound. Soaps (in the form of their sodium, potassium, and substituted ammonium salts,such as of poly- C 816 (R) ZQ6355 meri.zed fatty acids, may also be used, preferably j.n conjunction with an anionic and/or a nonionic synthetic detergent.

The amount of the active detergent material varies from 1 to 60%, preferably from 2 to 40% and particularly preferably from 5 to 25% by weight. When a soap is incorporated, the amount thereof is from 1 to 40i by weight.

Although not necessarily, the liquid compositions of the invention preferably also compri.se up to 60% of suitable builder materials, such as sodium, potassium and ammonium or substituted ammonium pyro- and tri-polyphosphates, -ethylenediamine tetraacetates, -ni-trilotriacetates, -ether polycarboxylates, -citrates, -carbonates, -orthophosphates, zeolites, carboxy-methyloxysucci.nates, etc. Particularly preferred are the polyphosphate builder salts, nitrilotriacetates, citrates, zeolites, and mixtures thereof. In general the builders are present in an amount of from 1 to 60%, preferably from 5 to 50% by weight of the final composition.

The amount of water present in the detergent compositions of the invention varies from 10 to 70% by weight.

Other conventional materials may be present in the liquid detergent compositions of the invention, for example sequestering agents, such as ethylenediamine-tetraphosphonic acid? non-builder electrolytes, such as alkalimetal-chlorides, -bromides, -nitrates and -sulphates; soil-suspending agents, such as sodium carboxymethylcellulose, polyvinylpyrrolidone or the maleic anhydri.de/vinylmethylether copolymer; hydro-tropes; dyes; perfumes; alkaline materials, such as silicates; optical brighteners; germicides; anti- C 816 (R) >6 3 ~ 5 tarnishing agents; suds boosters; suds depressants, such as liquid polysiloxane anti-foam compounds; enzymes, particularly proteolytic enzymes, such as the commercially available subtilisins Maxatase (ex Gist-Brocades N.V., Delft, The Netherlands), Alcalase and Esperase (both ex Novo Industri A/s, Copenhagen, Denmark) , amylolytic and cellulolytic enzymes; enzyme stabilizing systems, such as a mixture of a polyol with boric acid or an alkalimetal borate; oxygen liberating bleaches, such as sodium perborate or percarbonate, diperisophthalic anhydride with or without bleach precursors, such as tetraacetyl ethylene diamine; or chlorine liberating bleaches, such as dichlorocyanu-rate; anti-oxi.dants, such as sodi.um sulphites; opaci-fi.ers; fabric softening agents; stabilizers, such as polysaccharide hydrocolloids, e.g. partially acetylated xanthan gum, commercially available as "Kelzan" (ex Kelco Comp., New Jersey, USA); buffers and the like.

The invention is further illustrated by the following Examples, in which parts and percentages are by weight, unless indicated otherwise.

Example I The following composition was prepared: I ngredient; _% Sodium dodecyl benzene sulphonate 5.0 C^3~C^5 linear primary alcohol, condensed wi.th 7 moles of alkylene oxide (a mixture of ethylene- and propylene-oxi.de in a weight ratio of 92:8) 2.0 Anhydrous sodium tripolyphosphate 21.0 Amorphous silica (elem. parti.cle size 10 nm, surface area 700 m^/g) 3.0 Sodi.um carboxymethylcellulose 0.2 Foam depressant 0.3 C 816 (R) ■v •>. 2 063 5 Example I, Ingredients (continued) % Optical brightener 0.1 Stabilizer 0.2 Proteolytic enzyme * Enzyme stabilizer 10.0 Perfume 0.25 Water balance pH 8.0 * The enzyme was added in such an amount that the final product had a proteolytic activity of 9 GU/mg (733 GU/mg = 1 Anson unit/g).

To demonstrate the corrosion inhibiting action of the compositi.ons of the present invention the aforementioned composition was tested comparatively under various temperature conditions and degrees of water hardness.

Al-corroslon test In order to assess the corrosive action of a test wash liquor, circular plates of pure aluminium (99.5% Al) having a surface area of 40 cm' were cleaned to re-25 move surface grime and contaminants. They were rinsed with distilled water, dipped in methanol and air-dried. After being weighed the plates were subjected to the test liquor for a period of 8 hours, during which time the solution was stirred continuously. Sub-30 sequently the plates were cleaned, dried and weighed.

The corrosive action of the test liquor was expressed in weight loss of aluminium per m and per hour. In all tests the liquid detergent composition was dosed to the wash liquor at a concentration of 10 grams/-35 litre, unless stated otherwise.

C 816 (R) 8 Corrosion versus waterhardness t..t 2 0 6 3 5 By means of the corrosion test described above the composition of Example I was compared with a control composition (i.e. the example composition without the silica) at various degrees of water hardness at a temperature of 85°C. The hardness of the water is expressed in degrees of French hardness (one degree French hardness is equivalent to 10 mg CaCO^ per litre).

The following results were obtained: ° FH(Ca:Mg = 3:1) Weight loss of aluminium (g/m2/h) Comp.of Example I Control 0 12.5 25 37.5 50 4.0 2.4 1.1 0.4 .0.1 Corrosion versus temperature test By means of the corrosion test described above the composition of Example I was compared with the control composition at various temperatures using demj.nerali-zed water for the wash liquor.

The following results were obtained: Temperature (°C) Weight loss of aluminium (g/m2/h) Comp.of Example I Control I 0.4 40 I 0.8 50 <0.1 1.2 60 I 1.8 70 I 2.8 85 I 4.0 These results clearly show the corrosion inhibiting effect of the silica.

C 816 (R) ? A ■■O' «j! Example II The following composition was prepared: Ingredient: % Sodium dodecyl benzene sulphonate 7.0 lin. prim, alcohol, condensed with 7 moles of alkylene oxide (a mixture of ethylene oxide and propylene oxide in a weight ratio of 92:8) 2.0 Coconut potassium soap 1.0 Sodi.um tripolyphosphate 23.8 Amorphous silica (elem. particle size 10 nm, surf.area 700 m2/g) 2.0 Enzyme stabilizer 7.0 Proteolytic enzyme 9 GU/mg Sodi.um carboxymethylcellulose 0.1 Opti.cal brightener 0.1 Foam depressant 0.2 Perfume 0.3 Water balance pH 7.8 To illustrate the corrosive acti.on as a function of product dosage (and accordingly as a function of sili ca concentration) the composition of Example II was submitted to the corrosion test and compared with a control composition at different product dosages at a temperature of 85°C, using demineralized water for wash liquor.

The following results were obtained: C 816 (R) -> n 206355 Product dosage Silica Weight loss of aluminium (g/l) (ppm) (in g/m2/h) Comp . of Ex. II Control 200 <r 0.1 4.0 9 180 -*=■ 0.1 4.0 8 160 < 0.1 3.9 7 140 0.5 3.8 6 120 0.8 3.8 These results clearly indicate sion j.nhj.bition is provided if above 6 g/1, whj.ch corresponds silica. that effectj.ve corro-the product dosage is to 120 ppm by weight of Example III The following composition was prepared: Ingredient Sodium dodecylbenzene sulphonate 8.0 Sodium laurylethersulphate 0.5 C^2 lin.-prim. alcohol condensed wj.th 8 moles of ethylene oxide 2.5 Sodium pyrophosphate 11.0 Amorphous silica (elem. part. 10 nm, surface area 700 m2/g) 7.5 Enzyme stabilizer 10.0 Proteolytic enzyme 9 GU/mg Optical brightener 0.2 Water balance pH 8.0 The above composition was submitted to an experiment equivalent to the one carried out in Example II. As the above product should be used at a much lower dosage, the investigated range of product dosages is different.

C 816 (R) 2 06355 The following results were obtained: Product dosage Silica Weight loss of aluminium (g/1) (ppm) (in g/m2/h) Cornp. of Ex. Ill Control 3.0 225 < 0.1 1.7 2.5 188 -=0.1 1.5 2.0 150 0.4 1.3 1.5 113 0.7 1.1 The above test shows that at least 120 ppm and preferably 150 ppm of silica should be present in the wash liquor in order to provide effective corrosion inhibition .

Example IV To illustrate the anti-corrosive action of various types of silica the corrosion test was performed on a 20 set of composition prepared according to the formulation of Example 2 but differing therefrom in the type of silica employed. The amounts of silica incorporated equaled 10% by weight of the composition.

The following results were obtained at 85°C, zero water hardness and 10 g/litre in-wash product dosage. m C 816 (R) Si 1ica Type 12 Elem.part. Surface size area (nm) (m2/g) 2 06 •K C control Durosil 1) precipitated 25 Neosyl ET 2) precipitated 30 Ti xos il 38A 3) hydrogel 20 Gasil WP 1 2) hydrogel 1.5-2.0 Cab-O-Sil M5 4) pyrogenic 14 Aeros il 380 1) pyrogenic 7 Gasil 35 2) xerogel 3-5 Gasil 200 2) xerogel 1.5-2.0 50 250 250 850 200 380 300 700 Weight loss of aluminium (g/m2/h) 4.0 3.1 0.1 0.0 0.0 0.0 0.0 0.0 0.0 1) ex Degussa, Germany 4) ex Cabot Corp.Ill.,USA 2) ex Crosfield, UK 3) ex SI France Example V The composition according to example II was tested on its effectiveness in protecting enamel from corrosion attack.

The silica as specified in example II was included in an amount of 2.5% by weight. This composition at an in-wash dosage of 12 g/litre, zero waterhardness and 90°C, was subjected to an enamel adapted corrosion test similar to the above described Al-corrosion test.

Claims (10)

C 816 (R) 13 2063 As enamel corrosion is a somewhat slower process than metal corrosion, enamel covered steel plates were used having a surface area of 100 cm and the testing time was extended to a period of 24 hours. Results indicate a significant anti-corrosive action: Weight loss of enamel mc g/dm2/24 hours 10 for the control composition 101 for the sample composition 19 14 2.06355 WHAT1/WE CLAIM IS:

1. Aqueous liquid detergent composition with improved non-corrosive properties comprising detergent ingredients and an effective amount of silica having a surface area which is greater than 200 m2/gram.

2. Detergent composition according to claim 1 in which the silica is included in such amount that at the suitable in-wash dosage of the total detergent product a concentration of at least 120 ppm by weight of dissolved silica is established in the wash liquor.

3. Detergent composition according to claim 1 or 2 in which the silica is included in an amount of from 1 to 10% by weight of the total composition.

4. Detergent composition according to any one of the preceding claims in which the silica has an elementary particle size of less than 30 nm.

5. Detergent composition according to any one of the preceding claims in which the silica has a surface area which is greater than 500 m^/gram.

6. Detergent composition according to any one of the preceding claims in which the silica is included in an amount of from 2 to 4% by weight of the total composition.

7. Detergent composition according to any one of the preceding claims in which the silica has an elementary particle size of less than 10 nm. UK-claims C 816 (R) 206355

8. Detergent composition according to any one of the preceding claims which comprises from 5 to 25% by weight of detergent active materials of the anionic, nonionic, cationic and/or zwitterionic type, from 5 to 5 50% by weight of builder materials and from 2 to 4% by weight of the silica.

9. Detergent composition according to claim 1 and substantially as herein-before described with 10 reference to any one of the Examples.

10. Method of preventing corrosion of machine parts during washing, which comprises applying in the washing process a composition according to any one of 15 the preceding claims. ->A I fcD I Hli 22^d uh IVjoiJftrvNiacr A. J. PARK & SON b AGIMTS FOt ntt AffUCAHie, A \ 1 k i vOV ,'983'