US 3850852 A
Description (OCR text may contain errors)
United States Patent M US. Cl. 252-536 12 Claims ABSTRACT OF THE DISCLOSURE A detergent composition with an anionic, nonionic, amphoteric or zwitterionic detergent active compound and an alkali metal carbonate detergency builder includes a calcium sequestrant and a calcium carbonate anti-deposition agent to inhibit the formation of inorganic deposits on washed fabrics. Lower amounts of the sequestrant and anti-deposition agent are required together, than is necessary if the additives are used alone to inhibit deposition.
The invention relates to detergent compositions, and in particular to detergent compositions adapted for fabric washing.
Detergent compositions commonly incorporate as major ingredients detergent active compounds together with detergency builders. Conventional detergency builders are commonly inorganic materials, particularly the condensed phosphates, for example sodium tripolyphosphate. It has, however, been suggested that the use of phosphate detergency builders can contribute to eutrophication problems. Alternative detergency builders which have been proposed, for example sodium nitrilotriacetate (NTA) and synthetic polyelectrolyte materials, tend to be more expensive or less efficient than the phosphate detergency builders, or otherwise unsatisfactory for one reason or another.
It is known that sodium carbonate can function as a detergency builder by removing the calcium from hard Water in the form of precipitated calcium carbonate. But the calcium carbonate tends to accumulate on washed fabrics, which can lead to fabric harshness.
We have now found that a detergent composition with an alkali metal carbonate detergency builder is improved by incorporating therein a calcium sequestering agent and a calcium carbonate anti-deposition agent. The new compositions tend to form less inorganic deposits on washed fabrics, and hence give decreased fabric harshening. The
sequestering agent and the calcium carbonate anti-deposition agent appear to interact in decreasing inorganic deposition, which enables the effective use of lower levels of both additives than would otherwise be required, to decrease inorganic deposition, giving economic benefit and increased freedom in formulation whilst retaining detergent properties. Moreover, the use of lower levels of the sequestrant and the anti-deposition agent may be more acceptable for ecological reasons.
The alkali metal carbonate used is preferably sodium or potassium carbonate or a mixture thereof, for reasons of cost and efficiency. The carbonate salt may be wholly or partially neutralised, for example a sesquicarbonate may be used in partial replacement of the carbonate salt. The amount of the alkali metal carbonate in the detergent composition can be varied widely but the amount is desirably at least about 30%. by Weight, generally from about 40 to 60%, preferably from about 40 to 50% by weight. The amount of the carbonate detergency builder can approach about 80% by weight, whilst still leaving room for the calcium sequestrant, the anti-deposition agent 3,850,852 Patented Nov. 26, 1974 and detergent active compound or compounds, but normally other ingredients would be present which puts a practical limit of about 70% on the amount of the carbonate which can be used. It should be mentioned that within this range the higher levels tend to be required under conditions of use at low product concentrations, as is usually the practice in North America, and the converse applies at higher product concentrations as tend to be used in Europe. It may also be desirable to limit the carbonate content to a lower figure to decrease the risk of internal damage following any accidental oral ingestion.
The sequestering agent used is preferably an organic monomeric polycarboxylic sequestering agent, which should have a calcium ion sequestering capacity sufficient to decrease the concentration of free calcium ions in a solution containing 1.2x l0" M of calcium ions to a com centration of not more than about 2.0 10- M, generally from about 2.0 10 M to about l l0- M, when the sequestering agent is employed in an amount of 0.1% by weight of the solution. The level of calcium ions in an aqueous solution can be determined using a calcium specific electrode which develops a potential across a thin layer of a water-insoluble ion-exchange liquid which is held rigidly by an inert porous membrane disc. The liquid is a calcium salt of an organic phosphoric acid which exhibits very high specificity for calcium ions. An internal solution of calcium chloride contacts the inside surface of the membrane disc to provide a stable potential between the internal reference electrode and the ion-exchange liquid layer. In use, the calcium-specific electrode is immersed in a solution containing l.2X10- M of calcium ions and a solution of the sequestering agent under test is added in increments over 1 hour at 25 C. The potential generated is determined and related to that of standard solutions to find the calcium ion concentration in the presence of 0.1% of the sequestrant under test.
Many suitable sequestering agents are known and are commercially available. Examples of suitable sequestering agents include the water-soluble salts of aliphatic hydroxypolycarboxylic acid sequestrants such as citric acid, cyclic aliphatic and aromatic polycarboxylic acids such as cyclopentane tetracarboxylic acid and mellitic acid, and salts of polycarboxylic acids containing ether links, such as oxydiacetic acid, oxydisuccinic acid and carboxymethyloxysuccinic acid, and homologues and analogues of these compounds, and sodium nitrilotriacetate. Mixtures of two or more of these suitable sequestering agents may be used if desired, for example because of supply or biological problems. It will be appreciated that these compounds are usually used in water-soluble or dispersible salt form, particularly as the alkali metal, for example sodium, salts or as the ammonium or substituted ammonium salts, but it may be possible to use the sequestrants in acid form for neutralisation in solution. The sequestering agent is conveniently sodium citrate which is commercially available and biologically acceptable. The amount of the sequestering agent which is used should be at least about 1%, preferably from about 3% to 15%, for example from about 5 to 10%, by weight of the composition. The maximum level of the sequestering agent is about 30% and is dictated by practical considerations, particularly the cost of the sequestering agent in relation to other ingredients.
Suitable calcium carbonate anti-deposition agents are known compounds which are commercially available; they appear to act by interfering with the orderly pattern of deposition of calcium carbonate molecules at the crystal face. Some calcium carbonate anti-deposition agents are of course more eflicient than others, and the amount of an anti-deposition agent used depends on its effectiveness. Generally speaking the amount used is of the order of from about 0.5 to 5% by weight but some compounds are effective under good conditions at very low levels of as little as about 0.05% by weight, whilst others can usefully be used under adverse conditions at levels of up to about or even higher up to say about by weight. It will be appreciated that, if desired, more antideposition agent may be used than is necessary for effective anti-deposition properties. However, if the antideposition agents contain phosphorus, as for example in the case of sodium ethane-l-hydroxy-l,l-diphosphonate and sodium tripolyphosphate, it may be desirable to limit their content in the compositions to amounts of for example not more than about 10%, preferably 5% by weight of the compositions.
All calcium carbonate anti-deposition agents appear to have some calcium sequestering properties and they inhibit the growth of calcium carbonate crystals, but all calcium sequestrants are not effective anti-deposition agents, for example NTA, sodium carboxymethyloxysuccinate and sodium oxydiacetate. The presence of antideposition agents will tend to decrease the calcium ion activity in solution by sequestration; this apparently contributes to but does not wholly account for the decrease in deposition of calcium carbonate onto fabrics during washing with compositions according to the invention. A calcium sequestrant which is also an anti-deposition agent should normally be employed in the latter function in the compositions of the present invention as less anti-deposition agent than sequestrant is generally required. The same material will not of course be used as both the calcium sequestrant and the anti-deposition agent in a single composition.
A test to determine whether or not a compound is a calcium carbonate anti-deposition agent in a composition in accordance with the present invention is accomplished using a Terg-O-Tometer as follows: 5 mls. of a detergent solution is prepared with a concentration of 15 gram/ litre in Demineralite water at 50 C. and added to a Terg-O-Tometer test tube, and mls. of water of 18 French hardness (H) (Ca++:Mg++=2:1) also at C. is added to form 50 mls. of a solution containing the ,product in water of 18 H at a concentration of 0.15% by weight. The detergent composition used to prepare the solution contains by weight of sodium carbonate, 12%. by weight of anonionic detergent active compound a condensation product of a sec-linear (C -C alcohol with 9 moles of ethylene oxide, obtained as Tergitol 15-S 9 and from 1 to '15 by weight of the compound under test, with the balance being water.
A clean 3" x 1" microscope glass slide is fitted in a vertical position to a stirrer and washed in the solution for 5 minutes at 50 C. whilst being agitated at 30 oscillations per minute. In the case of compounds having no anti-deposition properties, a white deposit is apparent on the glass slide, particularly when viewed against a matt black background. If there is no significant inorganic deposit on the glass slide after I wash cycle, the procedure is repeated 4 times and after the fifth wash cycle the glass slide is examined again. If there is still no inorganic deposit or only a very slight trace of deposit, the compound under test is considered to be an effective anti-deposition agent at the concentration used.
Examples of calcium carbonate anti-deposition agents which are effective at the concentrations shown are given below:
Anti-deposition agent Percent Sodium ethane-l-hydroxy-l,l-diphosphonate 0.3
Sodium tripolyphosphate 1 Sodium hexametaphosphate 1 Sodium polyacrylate (MW 2000) 3 .Sodium copolyethylene-maleate (1 1) 2 'Sodium copolyethylene-maleate (1:1) 3 Sodium polyacrylate (MW 27,000) 3 Sodium 2,3-dicarboxylcellulose 3 Sodium copolyvinylmethylether-maleate 3 (1:1) 5
See footnotes at end of table.
TABLEContinued Anti-deposition agent Percent Sodium copolyisobutylene-maleate 4 (1:1) 5 Sodium salts of oxidised starches or cellulose (with 7090% of anhydroglucose rings opened at the 2.3 position to form dicarboxyl units) 5 Tetrasodium cyclopentane-cis 1,2,3,4 tetracarboxylate 10 Tetrasodium tetrahydrofuran tetracarboxylate 10 1 EMA 11 supplied by Monsanto Limited.
2 EMA 1103 supplied by Monsanto Limited.
3 Gantrez AN 119 supplied by GAF.
* Degree of polymerization of about 6.000.
Whilst the anti-deposition agents are effective in preventing calcium carbonate deposition under the test conditions at the levels shown, in practice when washing soiled fabrics it may be necessary to use different, usually higher, levels, of the anti-deposition agents for optimum results. But when the anti-deposition agents are used with the sequestrants in the compositions of the invention, lower amounts of the anti-deposition agents shown may be effective.
It will be appreciated that some calcium carbonate antideposition agents contain phosphorus, which may prevent their use if the detergent compositions are to be phosphorus-free. Sodium ethane-l-hydroxy-l,l-diphosphonate (EHDP) is such an anti-deposition agent which has been found to be particularly effective. In general, of the nonphosphorus-containing anti-deposition agents, the polymeric polycarboxylate compounds such as sodium polyacrylate and maleate copolymers are preferred, as these can confer additional beneficial properties on the compositions which are described in the literature. The antideposition agents can be used alone or in combination with other anti-deposition agents.
In addition to the essential carbonate compound and the calcium sequestering agent, it is possible to include minor amounts of other detergency builders, provided that the total amount of the detergency builders does not exceed about by weight, so as to leave room in the compositions for other essential ingredients. One such optional ingredient which has a detergency building effect is an alkali metal silicate, particularly sodium silicate, for example sodium alkaline or metasilicate. A low level of silicate, for example about 5-10% by weight, is usually advantageous in decreasing the corrosion of metal parts in fabric washing machines and may give process benefits, as well as assisting to control the pH of the composition which should be about 9 to 11, preferably about 10 to 11 for a wash solution at the desired product concentration. If higher levels of silicate are used, there can be a noticeable improvement in detergency, whichmay permit some decrease in the alkali metal carbonate content. However, the presence of a significant amount of silicate can apparently interfere with the action of the calcium carbonate anti-deposition agent so that for effective antideposition more of the latter is needed, for example from about 3 to 10 times more than would otherwise have been sufficient.
Other detergency builders which can be present in minor amounts, include particularly other so-called precipitant builders which form insoluble calcium salts, for example sodium orthophosphate, sodium salts of. long chain alpha-sulphonated monocarboxylic acids and sodium alkyl and alkenyl succinates and malonates and analogous compounds. 'It will be appreciated that some of these materials contain phosphorus which may detract from their usefulness in any compositions specifically intended to have a low level of phosphorus, or none at all.
The detergent active compounds used in the compositions of the invention may be any of the conventional anionic, nonionic, amphoteric orzwitterionic detergent active compounds and mixtures thereof, but preferably they do not form excessively water-insoluble calcium salts in hard water during use. Many such detergent active compounds are commercially available and are fully described in the literature, for example in Surface Active Agents and Detergents, Vols. I and II by Schwartz, Perry & Berch. Preferred suitable detergent active compounds which can be used include nonionic detergent active compounds which cannot of course form calcium salts, and anionic detergent active compounds which form water-soluble calcium salts, as for example alkyl ether sulphates, or which form insoluble calcium salts when used alone but are used in conjunction with additional solubilising compounds, particularly other detergent active compounds, for example mixtures of sodium alkyl benzene sulphonates with nonionic detergent active compounds and some mixed olefin sulphonates, wherein some of the olefin sulphonate constituents appear to act as solubilising agents for the other lesssoluble constituents.
Specific nonionic detergent active compounds which can be used in the compositions of the invention include ethoxylated fatty alcohols, preferably linear monohydric alcohols with C -C preferably C -C alkyl groups and about 5-15, preferably 7-12, ethylene oxide (EO) units per molecule and ethoxylated alkylphenols with C -C alkyl groups preferably C -C alkyl groups, and from about 4-12 EO units per molecule. The nonionic compounds are often used in admixture with minor amounts of other detergent-active compounds especially anionic compounds, to improve lather characteristics and powder properties. Mixtures of nonionic compounds with amine oxide can also give good results.
The preferred anionic detergent active compounds which form soluble or only slightly insoluble calcium salts are alkyl (C -C sulphates and alkyl ether (1-20 E0) sulphates, particularly those with C -C alkyl groups and 1 to 7 E0, and olefin sulphonate detergent active compounds, which latter term is herein used to mean the mixture of anionic detergent active compounds obtained when the products of the sulphonation of olefins are neutralised and hydrolysed. The olefins used are preferably linear C -C alpha-olefins particular C -C alpha-olefins, produced for example by the crackedwax process, or by the Zeigler process, but localised internal, random or so-called vinylidene olefins may alternatively be used. The anionic detergent active compounds are used in the form of the alkali metal, ammonium or substituted ammonium salts, preferably the sodium salts.
Other detergent active compounds which do not form insoluble calcium'salts, but which are of less commercial interest, include salts of esters of alpha-sulphonated (C -C fatty acids with C -C alcohols, preferably C -C alcohols; salts of 2-acyloxyalkane-l-sulphonic acids, particularly wherein the alkyl group contains from about 10-22, preferably 12-16, carbon atoms, and the ester forming group contains from 1-8 carbon atoms; trialkyl amine oxides having a C -C alkyl group, and two C -C alkyl or C -C hydroxyalkyl groups; and dialkyl sulphoxides having a C -C alkyl group and a C -C alkyl or C C hydroxy alkyl group, together with detergent active betaines and sulphobetaines.
As stated earlier, mixtures of some detergent active compounds can give particularly good results. Specifically, alkyl benzene sulphonates (which when used alone tend to form insoluble calcium salts) can be used with minor amounts of certain solubilising compounds, such as nonionic, alkyl sulphate or alkyl ether sulphate detergent active compounds, to give good detergent properties and be relatively economical. The ratio by weight of such solubilising compounds to the alkyl benzene sulphonate is preferably from about 1:1 to 1:10, especially from about 1:2 to 1:8.
invention can contain any of the conventional fabricwashing detergent composition additives in the amounts in which such additives are normally employed in fabricwashing detergent compositions. Examples of these additives included lather boosters such as alkanolamides, particularly ethanolamides derived from palm kernel fatty acids and coconut fatty acids, lather depressants, antiredeposition agents such as sodium carboxymethylcellulose, oxygen-releasing bleaching agents such as sodium perborate and sodium percarbonate, per-acid bleach precursors, chlorine-releasing bleaching agents such as trichloroisocyanuric acid, inorganic salts such as sodium sulphate, and, usually present in very minor amounts, fluorescent agents, perfumes, enzymes, germicides and colourants.
The detergent compositions of the invention may be produced by any of the techniques commonly employed in the manufacture of fabric-washing detergent compositions, including particularly slurry-making and spraydrying processes, and the compositions may be prepared in any of the common physical forms associated with fabric-washing detergent compositions, such as powders, granules, cakes and liquids.
Compositions according to the invention are further illustrated by the following Examples, in which parts and percentages are by weight, except where otherwise indicated, and water hardness is given in degrees of French hardness (H).
Examples 1 to 5 A series of detergent compositions were prepared with the following formulations:
Percent in each product Ingredient:
N onionic detergent active compound 12 12 12 12 12 Sodium carbonate 40 40 40 40 40 Trisodium citrate 5 10 10 Disodium malate 10 Tristgdium carboxymethyloxysuccina e Sodium copolyethylene-maleate (1:1) 2 2 2 2 2 Alkaline sodium silicate 10 1 Tergitol 15-8-9, a condensation product of linear-secondary (C alcohol with 9 moles of ethylene oxide (E0), from Union Corporation.
1 EMA 11 from Monsanto Chemicals Limited.
These compositions were tested for the levels of inorganic deposits on cotton terry towelling by ashing known weights of fabric at 700 C. after Washing them a varying number of times in Whirlpool washing machines using a product concentration of 0.15% in 18 H water (Ca++:Mg++, 2:1)
at 48 C. The results were as follows:
Number of wash cycles Percent inorganic deposit 7 Example 6 A spray-dried detergent composition was prepared to thefollowing formulation:
Ingredient: Percent Nonionic detergent active compound 1 12 Sodium carbonate 45 'Trisodium citrate Sodium copolyethylene-maleate (1:1) 2 Sodium sulphate 2O Fluorescent agents 0.23
Water to 100.
1 Tergitol -8-7, as in Examples 1 to 5 but with 7 moles of ethylene oxide.
2 EMA 11.
This powder was compared with a commercially available detergent composition based on sodium dodecyl benzene sulphonate and sodium tripolyphosphate by washing domestically soiled halved articles in the different products in Whirlpool washing machines at 0.15% product concentration. The results showed the products to have very similar detergencies as the halved articles washed with both products were equally preferred by the assessors.
The levels of inorganic deposits on the washed fabrics were determined and found to be about 0.2% after 8 wash cycles for both compositions.
Examples 7 and 8 Two powdered detergent compositions were prepared by conventional spray-drying techniques to the following formulations:
Sodium dodecyl benzene sulphate 16 16 Sodium alkyl ether sulphate 4 4 Sodium carbonate 45 45 Sodium citrate 5 Trisodium carboxymethyloxysuccinate. 5 Sodium copolyethylene-maleate (1:1) 2 2 Sodium sulphate 18 18 Water 10 10 Terry towelling Cotton sheeting 5 wash 10 wash 5 Wash 10 wash Composition cycles cycles cycles cycles Example The fabrics washed with both compositions felt soft after 10 wash cycles.
Examples 9 and 10 Two detergent compositions were prepared by conventional mixing techniques to the following formulations:
9 10 Ingredient, percent:
- 'Sodium dodecyl benzene sulphate 16 16 Tergitol 15-S-9 (as in Examplm 1-5) 4 4 Sodium carbonate 45 45 i Sodium citrate 5 5 EMA 11 (as in Examples 1-5) 2 we Gantrez AN119 5 7O Water to 100 100 1 Sodium copolyvinylmethylether-malcate (1:1) from General Aniline and Film Corporation.
sheeting with the following results (after 5 or 10 wash cycles).
Percent inorganic deposit Terry Cotton Composition towelling sheeting Example:
9 (1C wash cycles) 0.2 0:3
10 (5 wash cycles) 0. 1 0.1
Examples 11 and 12 Two detergent compositions were prepared by conventional techniques to the following formulations:
Sodium dodceyl benzene sulphate 16 20 Sodium alkyl ether sulphate 4 Sodium carbonate 45 45 Sodium citrate 5 5 Sodium copolycthylcne-maleate (1:1) 2 2 2 Water to 100 100 l 2 As in Examples 7 and 8.
These compositions, which both had low inorganic deposition properties, were evaluated for their detergent properties in washing a variety of artificially soiled test cloths in a Terg-O-Tometer under standard conditions at 0.15% product concentration in water of 18 H at 50 C. The detergency test results were as follows:
Percent detergency- T estcloth Composition A 1 B 2 C 3 Example 1 65% Dacron polyester/35% cotton test cloth soiled with vacuum cleaner dust.
2 Cotton poplin test cloth soiled with 4 parts of fatty soil and egg albgrpin and 1 part of particulate soil (60% clay, 30% carbon, 10% ferric OX1 6 3 Cotton test cloth soiled with a mixed fatty soil and particulate soil (10%) of indian ink and ferric oxide.
Examples 13 and 14 Percent detergency- Test cloth Composition A B C The results of Examples 11 to 14 show the benefit of adding the sodium alkyl ether sulphate detergent active compound to decrease the tendency of the alkyl benzene sulphonate to be precipitated in the form of its insoluble calcium salt.
Examples 15 and 16 Four detergent compositions which included two comparative products A and B were prepared by admixture of the ingredients shown below, and the compositions were then used to wash cotton terry towelling as described in Examples 1 to 5 giving the inorganic deposits shown after 10 wash cycles.
It can be seen that neither the sequestrant nor the antideposition agent alone was effective at the levels used in decreasing the inorganic deposition, whereas the mixtures in the Examples gave excellent low ash figures.
Example 17 A detergent composition was prepared with the following ingredients:
Ingredient: Percent Sec-linear alcohol (C C )9 EO 12 Sodium sesqnicarbonate 50 Trisodium citrate Sodium copolyethylene-maleate (1:1) 2
water to 100.
This composition has a pH of 9.6 at a product concentration of 0.15%, as compared with a pH for a comparative composition with sodium carbonate instead of sodium sesquicarbonate of about 10.2.
This composition was tested for inorganic deposition on cotton terry towelling and found to give results of about 0.2% after 5 and wash cycles and in a standard Terg-O-Tometer test using a cotton test cloth soiled with a mixed fatty, proteinaceous and particulate soil, the detergency was similar to that for a commercially available sodium tripolyphosphate-built product.
What is claimed is:
1. A detergent composition comprising from about 5 to 40% of an anionic, nonionic, amphoteric or zwitterionic detergent active compound, from about 30% to 70% of an alkali metal carbonate detergency builder, from about 1% to 30% of an organic monomeric polycarboxylic se questrant for calcium ions and from about 0.05% to of an anti-deposition agent for inhibiting the deposition of calcium carbonate formed by reaction between the alkali metal carbonate detergency builder and calcium ions in hard water during use of the composition, the percentages being expressed by weight of the composition.
2. A detergent composition according to Claim 1 wherein the amount of the organic monomeric polycarboxylate sequestrant is from about 3 to 15% by weight of the composition.
3. A detergent composition according to Claim 2, wherein the organic monomeric polycarboxylate sequestrant is sodium citrate.
4. A detergent composition according to Claim 1, wherein the alkali metal carbonate is sodium carbonate or sodium sesquicarbonate.
5. A detergent composition according to Claim 1, wherein the amount of the alkali metal carbonate is from about 40 to by weight of the composition.
6. A detergent composition according to Claim 1, wherein the amount of the anti-deposition agent is from about 0.5 to 10% by weight of the composition.
7. A detergent composition according to Claim 1, wherein the anti-deposition agent is a polymeric polycarboxylate compound.
8. A detergent composition according to Claim 1, wherein the anti-deposition agent is sodium ethane-l-hydroxy-1,1-diphosphonate, sodium tripolyphosphate or sodium hexametaphosphate.
9. A detergent composition according to Claim 1, wherein the amount of the detergent active compound is from about 10 to 30% by weight. of the composition.
10. A detergent composition according to Claim 1, wherein the detergent active compound is a nonionic compound.
11. A detergent composition according to Claim 1, wherein the detergent active compound is an alkyl sulphate, alkyl ether sulphate or olefin sulphonate detergent active compound.
12. A detergent composition according to Claim 1, wherein the detergent active compound is a mixture of an alkyl benzene sulphonate detergent active compound and a solubilising nonionic, alkyl sulphate or alkyl ether sulphate detergent active compound.
References Cited UNITED STATES PATENTS 3,679,589 7/1972 Schnegelberger et al. 252156 2,575,576 11/1951 Bacon et :al. 252-535 3,728,266 4/1973 Komeda et al. 252534 FOREIGN PATENTS 1,124,186 8/1968 Great Britain 252-156 467,585 2/1971 Japan 252-534 LELAND A. SEBASTIAN, Primary Examiner US. Cl. X.R. 252-456, 531, 532, 533, 534, 535, 539, 540, Dig. 2, Dig. 17