CA1221293A

CA1221293A - Liquid detergent composition

Info

Publication number: CA1221293A
Application number: CA000441991A
Authority: CA
Inventors: Cornelis B. Donker; John R. Samuel
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1982-11-26
Filing date: 1983-11-25
Publication date: 1987-05-05
Also published as: BR8306514A; DE3377140D1; ATE35283T1; AU2162683A; NZ206355A; ZA838713B; EP0110472A3; AU550913B2; EP0110472A2; JPS6119678B2; JPS59140300A; EP0110472B1

Abstract

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 m2/gram. The inclusion of silica provides good non-corrosive properties both in respect to metal and enamel surfaces.

Description

~Z~293 C 816 (R) LIQUID DETERGENT COMPOSITIONS

The present invention relates to liquid detergent com-positions and in particular to aqueous liquid deter-gent compositions having improved non-corrosive properties.

It i5 desirable to include an anti-corrosion agent in detergent compositions in order to inhibit the corro-sive 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 sesquisilicate. Apart from their corrosion inhibiting action, such compounds provide the liquid detergent composition with a highly alkaline environment, which i5 not always a desirable circumstance, especially if in such compositions alka-li-sensitive ingredients are used. Further anti-corrosive agents described in the detergent art include sulphites, nitrites, carbonates, borax or organic com-pounds such as benzoates.

It has now been found that the corrosive action ofaqueous 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.

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2~3 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 concentra-tion of at least 120 ppm by weight and preferably 150 ppm by weight. According to the presen-t 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/l.

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/l product dosage.

The silica to be used in the present invention should have a surface area which is greater than 200 m2 per gram and preferably greater than 350 m2 per gram or even 500 m2 per gram. The upper limi~ of the surface area is not a cri~ical factor, but normally surface areas range to about 1200 m2 per gram.

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C 816 (R) In general such sili.cas have elementary particle sizes of less than about 30 nm, i.n particular less than about 25 nm. Preferably, elementary parti.cle sizes are less than 20 nm or even 10 nm. There is no criti.cal lower li.mit of the elementary particle size; the lower limi.t is governed by other factors such as the manner of manufacture etc. In general, commerci.ally available si.li.cas have elementary parti.cle sizes of 1 nm or more.

Suitable forms of silica include amorphous si.li.ca, such as precipi.tated sili.ca, pyrogeni.c sili.ca and si.l-i.ca gels, such as hydrogels, xerogels and aerogels, or the pure crystal forms quartz, tridymite or crystobal-i.te, but the amorphous forms of sili.ca are preferred.
Suitable sili.cas may readily be obtained commercially.
They are sold, for instance, under the Regi.stered Trade Names of Aerosil 380 (ex Degussa Corp., ~.J., USA), Cab-0-Sil M5 (ex Cabot Corp., Ill, USA), Tixosi.l 38A (ex SI Chi.mie, France) and Gasil 200 tex Crosfi.eld, UK).

The liquid detergent composi.tions of the i.nventi.on further comprise as essenti.al ingredient an active de-tergent material, which may be an alkali metal or al-kanolami.ne soap of ClO-C24 fatty aci.d, including polymeri.zed fatty acids, or an anioni.c, noni.onic, cat-ioni.c, zwi.tteri.oni.c 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 (i.ncluding sodi.um, potassium, ammoni.um and sub-sti.tuted ammonium salts, such as mono-, di- and tri-ethanolamine salts) of Cg-C20 alkyl benzene sulphon-ates, C8-C22 primary or secondary alkane sulphonates, C8-C24 olefi.n sulphonates, sulphonated polycarboxylic aci.ds, prepared by sulphonati.on of the pyrolized product ' ':: , . . .

:,'` ' C 816 (R) - :~L2~2~3 of alkali.ne earth metal ci.trates, e.g. as described in Bri.ti.sh Patent Speci.ficati.on No. 1 082 179, C8-C22 al-kyl sulphates, C~-C24 alkyl polyglycol ethersulphates, (containi.ng up to 10 moles of ethylene oxides), further examples are described in "Surface Acti.ve Agents and Detergents" (Vol. I and II) by Schwartz, Perry and Berch.

Exa~nples of nonioni.c syntheti.c detergents are the con-densati.on products of ethylene oxi.de, propylene oxi.de and/or butylene oxide with C8-C18 alkylphenols, C8-C18 primary or secondary ali.phatic alcohols, C8-C18 fatty aci.d ami.des; further examples of noni.oni.cs i.nclude ter-tiary ami.ne oxi.des wi.th one C8-C18 alkyl chain and two Cl-C3 alkyl chai.ns. The above reference also describes further examples of nonioni.cs.

The average number of moles of ethylene oxide and/or propylene oxi.de present i.n the above nonioni.cs vari.es from 1 to 30; mixtures of various nonioni.cs, includi.ng mi.xtures of nonioni.cs wi.th a higher degree of alkoxyl-ati.on, may also be used.

Examples of cati.onic detergents are the quaternary am-monium compounds such as alkyl dimethyl ammoni.um halo-genides.

Examples of amphoteric or zwi.tterionic detergents are N-alkylamino acids, sulphobetaines and condensation products of fatty aci.ds with protein hydrolysates, but owing to their relatively hi.gh cost they are usually used in combination wi.th an anionic or a nonionic de-tergent. Mixtures of the various types of active de-tergents may also be used, and preference is given to mixtures of an anioni.c and a nonionic detergent-active compound. Soaps (in the form of thei.r sodium, potas-si.um, and substi.tuted ammoni.um salts,such as of poly-~, :

C 816 (R) `` ~L22~L2~3 merized fatty acids, may also be used, preferably inconjunction with an ani.onic and/or a nonionic synthet-i.c detergent.

The amount of the acti.ve detergent material varies from 1 to 60%, preferably from 2 to 40~ and particu-larly preferably from 5 to 25~ by wei.ght. When a soap i.s i.ncorporated, the amount thereof is from 1 to 40 by weight.
Although not necessarily, the li.qui.d compositions of the invention preferably also comprise up to 60~ of suitable builder materials, such as sodium, potassium and ammonium or substituted ammoni.um pyro- and tri-polyphosphates, -ethylenediamine tetraacetates, -ni.-trilotriacetates, -ether polycarboxylates, -citrates, ~carbonates, -orthophosphates, zeolites, carboxy-methyloxysuccinates, etc. Particularly preferred are the polyphosphate bui.lder salts, nitri.lotriacetates, ci.trates, zeoli.tes, and mixtures thereof. In general the builders are present i.n an amount of from 1 to 60~, preferably from 5 to 50% by weight of the final compositi.on.

The amoun`c of water present in the detergent composi.-tions of the invention varies from 10 to 70~ by wei.ght.

Other conventi.onal materials may be present i.n the liquid detergent composi.tions of the invention, for example sequestering agents, such as ethylenediami.ne-tetraphosphonic aci.d; non-builder electrolytes, such as alkali.metal-chlorides, -bromides, -nitrates and -sulphates; soil-suspending agents, such as sodium carboxymethylcellulose, polyvinylpyrrolidone or the maleic anhydride/vinylmethylether copolymer; hydro-tropes; dyes; perfumes; alkaline materials, such as sili.cates; optical brighteners; germi.cides; anti-.. .~
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-C 816 (R) ~23L2~3 tarnishing agents; suds boosters; suds depressants, such as li.quid polysiloxane anti.-foam compounds; en-zymes, parti.cularly proteolytic enzymes, such as the commerci.ally ava;.lable subti.li.sins Maxatase ~ (ex Gi.st-Brocades N.V., Delft, The Netherlands~, Alcalase ~ andEsperase ~ (both ex Novo Industri A/S, Copenhagen, Den-mark), amylolyti.c and cellulolyti.c enzymes; enzyme sta-bi.li.zi.ng systems, such as a mi.xture of a polyol with bori.c aci.d or an alkali.metal borate; oxygen liberati.ng bleaches, such as sodium perborate or percarbonate, di.peri.sophthali.c anhydride wi.th or wi.thout bleach pre-cursors, such as tetraacetyl ethylene diami.ne; or chlori.ne li.berati.ng bleaches, such as di.chlorocyanu-rate; anti.-oxi.dants, such as sodium sulphi.tes; opaci.-fi.ers; fabri.c so~teni.ng agents; stabi.lizers, such aspolysacchari.de hydrocolloids, e.g. parti.ally acetylated xanthan gum, commerci.ally available as "Kelzan" (ex Kelco Comp., New Jersey, USA); buffers and the like.

The i.nventi.on is further i.llustrated by the following Examples, i.n whi.ch parts and percentages are by wei.ght, unless i.ndi.cated otherwi.se.

Example I
The followi.ng composi.ti.on was prepared:

Ingredient: %
-Sodium dodecyl benzene sulphonate5.0 C13-C15 linear pri.mary alcohol, con-densed wi.th 7 moles of alkylene oxi.de (a mixture o~ ethylene- and propylene-oxide in a weight rati.o of 92:~)2.0 Anhydrous sodi.um tripolyphosphate 21.0 Amorphous si.li.ca (elem. parti.cle size 10 nm, surface area 700 m2/g) 3.0 Sodium carboxymethylcellulose 0.2 Foam depressant 0.3 C 81~ (R) `- ~LZ2~1~93 ~xample I, Ingredi.ents (continued) %
Opti.cal hrightener 0.1 Stabi.lizer 0.2 Proteolyt;.c enzyme *
Enzyme stabilizer 10.0 Perfume 0.25 Water balance pH 8.0 * The enzyme was added i.n such an amount that the fi.nal product had a proteolyti.c activity of 9 GU/mg (733 GU/mg = 1 Anson uni.t/g).

To demonstrate the corrosion inhibi.ting action of the compositi.ons of the present i.nventi.on the aforemen-ti.oned composi.ti.on was tested comparatively under various temperature condi.tions and degrees of water hardness.
Al-corrosion test In order to assess the corrosive acti.on of a test wash li.quor, circular plates of pure alumi.nium (~9.5% Al) having a surface area of 40 cm2 were cleaned to re-move surface grime and contami.nants. They were rinsedwith distilled water, dipped in methanol and air-dried. After being wei.ghed the plates were subjected to the test liquor for a period of 8 hours, during whi.ch time the solution was stirred continuously. Sub-sequently the plates were cleaned, dried and weighed.The corrosive action of the test liquor was expressed in weight loss of aluminium per m2 and per hour. In all tests the liquid detergent composition was dosed to the wash liquor at a concentrati.on of 10 grams/-li.tre, unless stated otherwise.

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-~ 8 Corrosion versus waterhardness test By means of the corrosion test described above the composi.ti.on of Example I was compared wi.th a control composi.tion (i.e. the example compositi.on without the si.li.ca) at various degrees of water hardness at a tem-perature of 85~C. The hardness of the water i.s expres-sed in degrees of French hardness (one degree French hardness is equi.valent to 10 mg CaC03 per li.tre).

The followi.ng results were obtai.ned:
FH(Ca:~g = 3:1)Wei.ght loss of alumini.um (g/m2/h) _Comp.of Example I Control 0 1 4.0 12.5 1 2.4 c 0.1 1.1 37.5 1 0.4 c 0.1 Corrosion versus temperature test By means of the corrosion test described above the composi.ti.on of Example I was compared wi.th the control composi.ti.on at various temperatures usi.ng deminerali~
zed water for the wash li.quor.
The following results were obtained:
Temperature (C)Weight loss of aluminium (g/m2/h) Comp.of Example I Control 1 0.4 1 0.8 ~ 0.1 1.2 1 1.8 1 2.8 1 4.0 These results clearly show the corrosion inhibi.ti.ng ef~ect of the silica.

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C 81~ (R) .2~3 Example II
The following compositi.on was prepared:

Ingredi.ent: %

Sodium dodecyl benzene sulphonate 7.0 C13-Cl5 lin. prim. alcohol, con-densed with 7 moles of alkylene oxi.de ta mixture of ethylene oxide and propyl-ene oxide i.n a wei.ght ratio of 92:8) 2.0 Coconut potassium soap 1.0 Sodium tripolyphosphate 23.8 Amorphous silica (elem. parti.cle size 10 nm, surf.area 700 m2/g) 2.0 Enzyme stabi.lizer 7.0 Proteolyti.c 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 functi.on of product dosage (and accordingly as a function of sili ca concentrati.on) the composi.tion of Example II was submitted to the corrosion test and compared with a control compositi.on at different product dosages at a temperature of 85C, usi.ng demineralized water for the wash liquor.

The following results were obtai.ned:

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C 816 (R) ~2Z~913 Product dosage Si.lica Weight loss of aluminium (g/l) (ppm)(in g/m2/h) Com~. of Ex. II Control .~ .
10 200 G~ 0.1 4.0 9180 c 0.1 4.0 8 160 c 0.1 3.9 7 140 0.5 3.8 6 120 0.8 3.8 These results clearly i.ndicate that effective corro-si.on i.nhi.biti.on is provided if the product dosage is above 6 g/l, whi.ch corresponds to 120 ppm by wei.ght of silica.

E~ample III
The following composi.tion was prepared:

Ingredi.ent %
Sodi.um dodecylbenzene sulphonate 8.0 Sodi.um laurylethersulphate 0.5 C12 li.n.-prim. alcohol condensed wi.th 8 moles of ethylene oxide 2.5 Sodium pyrophosphate 11.0 Amorphous sili.ca (elem. part. 10 nm, 25 surface area 700 m2/g) 7.5 Enzyme stabili.zer 10.0 Proteolytic enzyme 9 GU/mg Opti.cal 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 di.fferent.

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C 816 (R) The following results were obtained:

Product dosage Silica Wei.ght loss of al~inium (g/l) (ppm~ (in g/m2/h) Comp. of Ex. III Control

3.0 225~c 0.1 1.7 2.5 188c 0.1 1.5 2.0 1500.4 1.3 1.5 1130.7 1~1 The above test shows that at least 120 ppm and preer-ably 150 ppm of sili.ca should be present i.n the wash li.quor in order to provide effecti.ve corrosion inhi.b-ition.
Example IV

To illustrate the anti-corrosive acti.on of vari.ous types of si.lica the corrosion test was performed on a set of composi.tion prepared accordi.ng to the formula-ti.on of Example 2 but di.fferi.ng therefrom in the type of sili.ca employed. The amounts of sili.ca incorporated equaled 10% by wei.ght of the composition.

The following results were obtai.ned at 85~C, zero water hardness and 10 g/litre in-wash product dosage.

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, : ' ' C 816 (R) Z~2~3 Silica Type Elem.part. Surface Weight loss size area of (nm) (m2/g) aluminium - -- - ~ (g/m2/h) control - - - 4.0 Durosil 1) precipitated 25 50 3.1 'i~
Neosyl ET
2) precipitated 30 250 0.1 Tixosil 1038A 3) hydrogel 20 250 0.0 Gasil WP
2) hydrogel 1.5-2.0 850 0.0 Cab-O-Sil M5 4) pyrogenic 14 200 0.0 15 Aerosil 380 1) pyrogenic 7 380 0.0 Gasil 35 2) xerogel 3-5 300 0.0 Gasil 200 202) xerogel 1.5-2.0 700 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 30 attack.

The silica as specified in example II was included in an amount of 2.596 by weight. This composition at an in-wash dosage of 12 g/litre, zero waterhardness and 35 90C, was subjected to an enamel adapted corrosion test similar to the above described A1-corrosion test.

.' C 816 (R) -` 12~ 93 As enamel corrosion is a somewhat slower process than metal corrosion, enamel covered steel plates were used having a surface area of 100 cm2 and the testing time was extended to a period of 24 hours.
Results indicate a significant anti-corrosive action:

Weight loss of enarnel mg/dm2/24 hours for the control composition 101 for the sample composition 19 : , ;: .-,;,~ .

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Aqueous liquid detergent composition with improved non-corrosive properties comprising detergent ingredients and an amount of silica of from about 1 to 10% by weight of the total composition, having a surface area which is greater than 200m2/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 in which the silica has an elementary particle size of less than 30 nm.

4. Detergent composition according to claim 1 in which the silica has a surface area which is greater than 500m2/gram.

5. Detergent composition according to claim 1 in which the silica is included in an amount of from 2 to 4% by weight of the total composition.

6. Detergent composition according to claim 3 in which the silica has an elementary particle size of less than 10 nm.

7. Detergent composition according to claim 1 which comprises from 5 to 25% by weight of detergent active materials of the anionic, nonionic, cationic and/or zwitterionic type, from 5 to 50% by weight of builder materials and from 2 to 4% by weight of the silica.

8. Method of preventing corrosion of machine parts during washing, which comprises applying in the washing process a composition according to claim 1.