CA1042753A - Detergent compositions - Google Patents

Abstract

ABSTRACT
An additive comprising a soluble aluminate and an organo phosphonic acid for automatic dishwasher detergent compositions is disclosed. Overglaze pattern corrosion is reduced employing such additives.

Description

This invention relates to detergent compositions having improved properties and to additives to detergents to improve the properties thereofO
It particularly relates to detergent compositions which may be used in auto-matic dishwashing machines.
The use of automatic dishwashing machines particularly those used in canteens rather than domestically, places demanding requirements on the detergent. Thus, the detergent, be it solid or liquid must be capable of being automatically dosed, must have as high as possible detergent strength in order that it may be economical in operation and be quick acting so that 10 it may meet the requirement of being useful in the very short wash cycle which is now common in commercial automatic dishwashing machines, that i9 of the order of 45 seconds.
In view of the above objectives development in detergents of the type referred to has been towards detergents containing as high a level of deter-gency as possible which detergency is aggressive in action. Such requirements are for example met to a certain extent by alkali metal hydroxides and alkali materials of similar aggressiveness, such as alkali metal carbonates and s ilicate s .
` The use of such detergents lead to a number of problems. One of 20 the major problems is corrosion of on-glaze colours on pottery. An increasing quantity of crockery is patterned after initially firing the base glaze at a high temperature and then firing on the pattern at a much lower temperature. This type of decoration is employed because a greater spectrum of colour can be used in the designO However on-glaze decoration is very susceptible to attack by alkaline solutions. Corrosion of the glaze, or even complete break-up and removal of the pattern is naturally very undesirable and contra indicates the use of detergents of the type referred to for washing such crockery.
A study of the corrosiveness of various individual components of 30 machine dishwashing compositions has been made by C. E. L. Franklin and V.A. Tindall, British Ceramic Research Association (B. C.R.A. )O Research ~' ~: . .. . .
'- . , : , -104'~7S3 Paper No. 265, 1954. A test has been devised by the B.C.R.A. for measuring the degree of glaze attack and colour removal and this is re-ferred to later. The usefulness of chemicals designed to inhibit the mechanism of corrosion which these workers postulated was also investigated by them. They found that soluble aluminates were very useful as corrosion inhibitors. United States Patent 2,241,984 describes the use of aluminates in preventing the corrosion of glass bottles when washing them with aluminates.
The use of zinc and beryllium compounds for the same purpose has also been mentioned.
The incorporation of a soluble aluminate in a detergent of the type referred to leads to difficulties. Firstly if the detergent is in powder form and a soluble aluminate is added to it, a flocculant precipitate results when this powder is dissolved in water to form the solution which is dosed in the machine. This precipitate may block feed lines, valves, coat conductivity probes and produce associated difficulties which makes the use of such detergents impracticable. As regards liquid detergents, soluble aluminates do not in general have a high enough solubility to be completely dissolved ` at the strength at which they have to be used to be effective.
If the ratio of soluble aluminate to alkaline hydroxide or salt is 20 raised to a level which is non-corrosive to on-glaze colours, then the compo-sition is found to have poor detergent properties.
We have found that these disadvantages may be reduced or overcome by adding to the alkaline detergent a material which acts synergistically with the aluminate to reduce the corrosiveness of the composition towards glazed pottery and glass and also enhances the hard water tolerance of the compo-s ition .
In experiments which we have carried out and which are detailed later we have determined that the addition of an amino-alkylene phosphonic acid to a detergent containing sodium hydroxide and sodium aluminate has 30 the effect of reducing the overglaze colour attack and reduces the precipita-~..

tion of insoluble salts from hard water on addition of the alkaline composition.

104~753 Also by the use of this composition it is pc)ssible effectively to replace apart of the sodium aluminate with an aminoalkylene phosphonic acid whilst producing these enhanced effectsO Therefore the disadvantage attendant on the use of a high concentration of sodium aluminate is reduced. Also the deleterious effect of a high concentration of sodium aluminate on the detergency of the composition as a whole is reduced.
The invention therefore provides a mixture for addition to a detergent to reduce ceramic overglaze pattern corrosion which comprise9 a soluble aluminate and an organo phosphonic acid or phosphonate.
The invention also provides a detergent composition of a high level of alkalinity including a mixture according to the invention.
Reference to a high level of alkalinity means that the detergent is one which contains an alkali metal hydroxide and/or alkali metal salts of similar levels of aggressiveness such as alkali metal carbonates and silicates.
The invention also provides a method of reducing the overglaze pattern corrosion of an aqueous system having a high level of alkalinity in which comprises providing for the presence in said system of an alkali metal aluminate and an organo phosphonic acid in concentrations effective to reduce overglaze pattern corrosion in said system.
- 20 The soluble aluminate is preferably an alkali metal aluminate, in particular sodium aluminate. The organo phosphonic acid is preferably an aminoalkylene phosphonic acid which may be defined by the formula:

A
` /N - R
A~
in which A represents /OH
CH2 - P ~
OH
30 and Rl represents the group A or the group -(CH2)X - ¦rN-(CH2)xl -N-A

~R2 ~y R3 : -- . .

10427s3 wherein R2 and R3 which may be the same or different, represent hydrogen or the group A; x is 2 or 3, and y is 0, or an integer frorn 1 to 4 or the group.
/A
-(CH2)z -CH-CH-N
, R4 Rs R6 in which R4 represents hydrogen and R5 represents an alkyl group or R4 and R5 together represent an alkylene group and R6 represents hydrogen or the group A and z represents 0 or 1.
Preferred aminoalkylene phosphonic acids are amino trialkylene 10 phosphonic acids; a particularly preferred phosphonic acid is amino tri-(methylene phosphonic) acid.
The aminoalkylene phosphonic acids may be used in the form of their salts, in particular as alkali-metal, preferably sodium, salts.
Other phosphonic acids may also be used in place of the amino-alkylene phosphonic acids. For example aceto-diphosphonic acid (A) and ethylene - 1, 1- dipho sphonic acid ( B ) (A) HO\O CH2OH O/OH (B) HO\O CH2 O/OH
P - CH - P ~P - C - P\
HO \OH HO \OH
may also be used.
The invention also extends to concentrates when made from deter-gents according to the invention by dilution with water.
The detergent composition may be in solid or liquid form and repre-sentative examples of such compositions are given in the Examples.
In the compositions according to the invention it is possible to have a very high proportion of alkali as indicated above. The detergent when in ~; powder form may in addition to the alkali contain sequestrants e. g. sodium tripolyphosphate, sodium hexametaphosphate and, tetrasodiumethylenedi-aminetetraacetate, metal corrosion inhibitors e. g. sodium metasilicate, 30 bleaches, e. g. chlorinated tri-sodium phosphate, sodium perborate and sodium sulphate and surfactants, e.g., ethoxylated alkyl phenols and sulphonated alkylated aromatics and other components such as suspending lO~ S3 agents, perfumes, fillers and alkaline salts. When in liquid form they may contain similar additional components suited to liquid formulations and thus may contain sequestrants, e.g. tetrapotassium pyrophosphate, alkaline salts, e.g., sodium silicates, ~urfactants, e.g. co-condensates of ethylene oxide and propylene oxide, bleaches, e.g. sodium hypochlorite and other minor components, e.g. hypochlorite stabili7ers, suspending agents, dyes, perfumes and viscosity modifiers.
The effective ratio of the aluminate to the organo phosphonic acid may be determined by experiment according to the test procedure described later herein. Suitable ratios are, however, generally within the range of 1:5 to 10:1 preferably 1:3 to 7:1 and particularly 1:1 to 3:1.
The detergent compositions of the invention represent detergents particularly suitable for machine dishwashing having a wash cycle of the order of 45 seconds having a very high level of alkaline detergency combined with a very low level of corrosion of ceramic gla7e.
In order that the invention may be more fully understood details of experimental work which has been carried out will now be described.
Various combinations of inhibitors were tested for inhibition of attack of alkaline hydroxides and alkaline salts upon overglaze patterns.
`` 20 The test procedure which follows the line of the Standard Test Procedure recommended by B. C.R.A. was as follows:
Standard test plates, (TOPIC pattern G & J Meakin Ltd., Stoke on Trent) after cleaning and degreasing in mild detergent solution, were immersed in a 0. 5% solution of the material under test at 170F for 32 hours, the solution being recirculated to maintain even temperature and concentra-tion. Not more than 20 square inches of ware surface should be exposed per litre of solution. At the end of this time, the plates were rinsed in tap water, rubbed dry with a clean linen cloth, and visually examined in good daylight. A group classification was awarded on the basis of the effect of the test solution on the colours and gla~e.

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1~)4Z753 Group 1 No noticeable affect on gloss or shade Group 2 Chiefly loss of gloss, but slight fading of colour may be noticeable.
Group 3 Gloss removed, and noticeable fading of colours.
Group 4 Considerable attack with a resultant removal of some colour.
Group 5 Very severe attack resulting in considerable, if not total, loss of colour.
Using this test method the effect of adding sodium aluminate and sodium amino-tri (methylene phosphonic acid) to a solution of sodium 10 hydroxide separately and in combination was studied. The results are set out in Table 1, 2 and 3 from which it can be clearly seen that the combina-tion of the two compounds is much more effective in reducing overglaze pattern corrosion than either compound aloneO

BY SODIUM HYDROXIDE WITH SODIUM ALUMINATE

Percentage Sodium Percentage Sodium Water Hydroxide Solution Aluminate in Hardness Corrosion -in Detergent. Detergent p.p.m. Grade CaC03 __________ ____ ______________ ____ _ ___ ______________ _ ____ ____ ` 20 7. 5 - 300 5 (Etching) 7.5 5.0 300 3 - 4 705 7.5 300 3 - 4 7.5 10.0 300 3 - 4 7. 5 5. 0 DISTILLED 3 - 4 7. 5 7. 5 DISTILLED 2 - 3 ' 7.5 15. 0 DISTILLED 2 _______ ______ ________________ _____________________ __________ ___ . ' ' 1~)42753 BY SODIUM HYDROXID:E WITH SODIUM AMINO
TRI(METHYLENEPHOSPHONATE) _ _ _ _ _ _ _ _ _ _ _ _ _ Percentage Sodium Percentage of Water Hydroxide in Sodium Amino Hardness Detergent . Tri(Methylene p. p. m.Corrosion Phosphonate) CaC03 Grade _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 7.5 0.5 300 2 - 3 7.5 1.0 300 3 10 7.5 2.0 300 3 7.5 3.0 300 3 - 4 7.5 0.5 DISTILLED 5 ;~ 7.5 2.5 DISTILLED 5 7.5 5.0 DISTILLED 5 ______________ __ _ ____ _ _ __ _______ ____ _ ______ ____ _________ ' -OF PATTERN OVERGLAZE USING SODIUM ALUMINATE
AND SODIUM AMINO TRI(METHYLENE PHOSPHONATE) ____________ :
Percentage Sodium Percentage Percentage Water Corrosion Hydroxide in Sodium Sodium Amino Hardness Grade 20 Detergent Aluminate in Tri (methylene p.. p. m.
:. Detergent Phosphonate) CaCO3 in Detergent _______________ ______________________________ _______ ___________ __ 7.5 - - 300 5 7.5 7.5 0.5 300 2 7.5 7.5 1.0 300 7.5 7.5 3.0 300 7.5 7.5 4.0 300 2 7.5 7.5 5.0 300 7.5 7.5 0.5 DISTILLED 5 7.5 7.5 2.5 DISTILLED 1 - 2 7.5 7.5 5O0 DISTILLED 1 - 2 ;~
_________________________________ _________ _________ ______________ :., - . : ~
.. . .

~!~)4;~753 Compositions as described in Table 3 are useful for washing dishes in automatic dishwashing machines. The composition given in Example 1 below is an illustration of a composition which was found to be a grade I
(non-corrosive) stable liquid which can be automatically dispensed and controlled in the dishwashing process, and was also effective in deterging general food soil from ceramics and in removing tea and coffee stains from ceramic cups:

Machine: Hobart XM with prewash Wash Temp: 145 - 150F
Rinse Temp: 155 - 182F
Water Hardness: 50 p.p.m.

Sodium hydroxide 2205 %
- ~ Sodium amino tr i (methylene pho sphonate ) 3.0%
Sodium aluminate 7.5~o Water 67.0 %
, 100. 0%

This example shows that compositions according to the invention -~ 20are also useful for washing milk or beverage bottles by an automatic process.
Various formulations details of the composition of each of which are given in Table 4, were tested in the following test:
In the process used in the test, the machine was a Davison Dominant provided with three detergent tanks. The first detergent tank was at a temperature of 55C, the second at a temperature of 66C and the third at a temperature of 49C. The rinse temperature was 21C and was followed by rinsing in untreated mains water: The water hardness was 330 ppm, of which 230 ppm was carbonate and the sodium hydroxide concentration was 0.6%.
Eighteen new one pint milk bottles were washed, dried and weighed.

Six bottles were placed in each of three thermostated water baths and com-pletely submerged in a solution of the composition under test made up in ~)4;~753 hard water (330 ppm CaCO3) to give 0.5% w/w sodium hydroxide. The baths were kept at 80C and, after one week, the bottles were removed, rinsed well in warm water (50C), dried and weighed. The bottles were then rinsed in a dilute solution of hydrochloric acid to remove any hard water scale, dried and weighed for the final time. From these weights (see Table 5) the amount of scale and the amount of glass corrosion was determined.
TABLE 4.
Formulation A B C
NaOH 100 TW 93.63%95.630% 100.00%

Amino -tri(methylene pho sphonic ac id) - 0.350 %
Sodium gluconate 4.55%0.003%
Sodium Aluminate - 0.350 %
Soft water 1.82%3.667%
:
Table 5 set out below demonstrates that a composition such as formulation B has the added advantage for bottle washing that the glass is not so vigorously attacked as with known compositions containing alkali and sequestrants. The results given in the table below were obtained by following 20 the test procedure described above to test three formulations A, B and C, in which A and C are known formulations and B is a composition according to the invention.

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- 10 _ ' .

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10427s3 BottleBottleBottlcBottleBottreBottle

2 3 4 5 6 Formulation A:
Initial wt. (g. ) 339.61340.24338.91340.98339.51338.62 Wt. after 1 week at 80C (g) 337.26337.90336.51338.62337.16336.26 Wt. after acid rinse(g)337.04337.71336.37338.42 336.95 336.07 Amount of scale (g) 0.22 0.19 0.14 0.20 0.21 0.19 10 Corrosion 10SB (g) 2.57 2.53 2.54 2.56 2.56 2.55 Formulation B:
Initial wt. (g) 349.32351.06351.52351.61349.60349.60 Wt. after 1 week at 80C (g) 349.33351.08351.53351.62349.61349.62 Wt. after acid rinse (g)349.32351.07351.523Sl.61 349.60 349.61 Amount of scale (g) 0.01 0.01 0.01 0.01 0.01 0.01 Corrosion loss (g) Nil +0.01 Nil Nil Nil +0.01 Formulation C:
Initial wt. (g) 349.98348.62349.91350.01350.61 349.81 20 Wt. after 1 week at 80C (g) 350.35349.06350.36350.34350.97 350.22 Wt. after acid rinse (g)347.96346.66347.91347.97 348.57 347.80 Amount of scale (g) 2.39 2.40 2.45 2.37 2.40 2.42 Corrosion loss (g) 2.02 1.96 2.00 2.04 2.04 2.01 Thus, it can be seen that under the conditions of test that Formula-tion B of the invention did not cause corrosion of the glass bottles whilst possessing the useful property of hard water scale control essential for such deter gents .

It is possible substantially to reduce the corrosiveness to crockery of a composition for use in automatic dishwashing by adding the synergistic inhibition system described. Thus, the following experiments illustrate the lO~Z753 usefulness of the invention in providing corrosion inhibition whilst ensuring good detergency in the product.
A test was devised to assess the ability of the detergent to remove tea stains from tea cups, which was as follows:
A solution of extracted tea was prepared by adding tea (2% w/w) to boiling water, allowing to stand for 5 minutes before filtering through a fine mesh sieve into a series of test cups. The volume of tea used was 120 mls. per cup and to this solution was added 10 mls of milk and 4 g of sugar. This solution was then allowed to stand for 1 hour after which 100 mls. of the volume in each cup was discarded and the remainder allowed to stand overnight. Thus the stained test cup was prepared.
Batches of 10 test cups were then subjected to a washing pro-cedure using a Hobart LE 4C washing machine, at 60C, using 270 p.p.mO
CaCO3 water and a detergent concentration of 1/2 oz. /gallonO
After washing the cups were grouped into the following categories:
Group 1: Perfectly clean Group 2: Slight staining still visible Group 3: Approximately 50% of stain removed.
`~ Group 4: Little stain removed.
' 20 Group 5: No stain removal.
The cups were then scored according to the group into which they were placed as follows:
Group 1: One point to Group 5: Five points Thus, the maximum score for a non-effective detergent was 50 - - points and for a perfect detergent 10 points.
It was found that this procedure could be repeated consistently and that an acceptable detergent had a score of about 30 at 1/2 oz. per gallon concentration.
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~04~5;:~
Thus, a triangular experiment was devised in which the compo-sition of a detergent was varied in three components. The properties of the various compositions, with regard to corrosion of crockery and removal of tea stains by the described method, were measured. The results are illustrated in the accompanying drawing.
FORMULATION COMPONENTS VARIATION

B. Tetra-Sodium-ethylenediamine-tetraacetate (38~o w.w. aqueous solution) 3% to Zl%
A. Sodium hydroxide 12% to 24%

C. Amino-tri(methylenephosphonic acid) (50% aqueous solution) 3% to 12%
Sodium aluminate F ixed at 7 .
Polyacrylic acid Fixed at 20 Balance Water Thus, it can be seen that the presence of the corrosion inhibition system described in this invention allows the formulation of an acceptable detergent with a much reduced tendency to corrode gla~e.

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Claims (16)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A mixture for addition to a detergent which comprises an alkali metal aluminate and a water-soluble organo phosphonic acid sequestering agent or a water-soluble salt thereof.

2. A mixture as claimed in Claim 1 in which the ratio of aluminate to phosphonic acid is from 1:5 to 10:1.

3. A mixture as claimed in Claim 2 in which the ratio of aluminate to phosphonic acid is from 1:3 to 7:1.

4. A mixture as claimed in Claim 3 in which the ratio of aluminate to phosphonic acid is from 1:1 to 3:1.

5. A mixture as claimed in Claim 2, 3 or 4 in which the aluminate is sodium aluminate.

6. A mixture as claimed in Claim 1 in which the phosphonic acid is an aminoalkylene phosphonic acid.

7. A mixture as claimed in Claim 6 in which the aminoalkylene phosphonic acid is a compound of the formula in which A represents the group and R1 represents the group A, the group where R2 and R3, which may be the same or different, represent hydrogen or the group A; x is 2 or 3 and y is 0 or an integer from 1 to 4, or the group in which R4 represents hydrogen and R5 represents an alkyl group or R4 and R5 together represent an alkylene group; R6 represents hydrogen or the group A and z represents 0 or 1.

8. A mixture as claimed in Claim 6 in which the amino alkylene phosphonic acid is an amino trialkylene phosphonic acid.

9. A mixture as claimed in Claim 8 in which the amino trialkylene phosphonic acid is amino tri(methylene phos-phonic) acid.

10. A mixture as claimed in Claim 1 in which the phosphonic acid is present in the form of its alkali metal phosphonate.

11. A mixture as claimed in Claim 10 in which the phosphonic acid is present in the form of its sodium phosphonate.

12. A mixture as claimed in Claim 1 in which the phosphonic acid is aceto-diphosphonic acid or ethylene-1,1-diphosphonic acid.

13. A mixture as claimed in Claim 1 in admixture with a detergent to form a detergent composition in which the mixture of aluminate and phosphonic component is from 0.1 to 99% by weight of the total composition.

14. A detergent composition as claimed in Claim 13 which is in powder form and which contains a sequestrant, metal corrosion inhibitor, bleach, surfactant, suspending agent, perfume, filler, and/or alkaline salt.

15. A detergent composition as claimed in Claims 13 or 14, which is in liquid form and which contains a sequestrant, alkaline salt, surfactant, bleach, hypochlorite stabilisers, suspending agent, dye, perfume and/or viscosity modifier.

16. A detergent composition which comprises an aqueous liquid solution or dilution of a composition as claimed in Claims 13 or 14.