GB2233338A

GB2233338A - Detergent composition

Info

Publication number: GB2233338A
Application number: GB8914461A
Authority: GB
Inventors: Prabudhha Ganguli; Ayodhya Nath Bhat; Subroto Das
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1989-06-23
Filing date: 1989-06-23
Publication date: 1991-01-09
Also published as: GB8914461D0

Abstract

A detergent composition, preferably in granular or powder form, comprises at least one detergent-active material and and at least one water-soluble builder salt in sodium salt form, and further comprises at least 0.1 wt% of a alkali metal polymer phosphate salt having the formula M2O-(MPO3)n wherein M is an alkali metal and n is an integer of at least 4, preferably at least 30; the alkali metal polymer phosphate salt being crystalline and at least partially in potassium salt form.

Description

DETERGENT COMPOSITIONS TECHNICAL FIELD The present invention relates to detergent compositions containing certain alkali metal polymer phosphate salts. Incorporation of these salts, especially in detergent compositions built with sodium tripolyphosphate or sodium carbonate or both, has been found to give detergency and antiredeposition benefits.

BACKGROUND AND PRIOR ART The inclusion of certain alkali metal polymer phosphate salts in detergent compositions has already been proposed. Polymer phosphates may generally be represented by the formula M20-(MPO3)n wherein M is an alkali metal, and n is an integer of at least 4, and may be as high as 400. Thus this formula encompasses all condensed phosphates higher than pyrophosphate (n=2) and tripolyphosphate (n=3).

Terminology in this area is somewhat confusing.

Historically the higher condensed phosphates have been given different names depending on the n-value, materials of relatively low n-value (molecular weight 500-2000) being known as Graham's salt, materials of medium n-value (molecular weight 2000-250 000) being known as Kurrol's salt, and materials of high n-value (molecular weight > 250 000) being known as Maddrell's salt. The term "hexametaphosphate", which strictly speaking refers to the material of n=12, is also sometimes used generically to refer to the lower-molecular-weight materials. It should be appreciated that the chemical structures of the polymer phosphates are not precisely defined, and some degree of ring foramtion or branching may be present in the otherwise normally linear polymer structure.

The inclusion of polymer phosphates in detergent compositions as builders, as antiredeposition agents and as antideposition (antiashing) agents, is known in the art.

EP 9954B (Unilever Case C.1035) discloses the incorporation of polymer phosphates of n-value 6-50, especiall about 18, in detergent compositions containing orthophosphate, in order to obtain reduced levels of inorganic deposits on washed fabrics. The materials used are referred to as Graham's salt or glassy phosphate; they are the water-soluble sodium salts.

The compositions preferably contain less than 10 wt% of other phosphates, and especially less than 5 wt% of sodium tripolyphosphate.

EP 28 143B (Unilever Case C.1052) discloses detergent compositions built with ortho- or pyrophosphate and containing the alkali metal polymer phosphate of EP 9954B, in delayed release form. The compositions preferably contain less than 10 wt% of other phosphate builders, and especially less than 5 wt% of sodium tripolyphosphate.

GB 2 040 981B (Procter & Gamble) discloses detergent compositions containing surfactant, zeolite builder, 1-3 wtZ of a water-soluble polyphosphate builder salt, and a water-soluble maleic copolymer. The polyphosphate builder salt may be sodium tripolyphosphate or a higher polyphosphate, for example, a glassy metaphosphate (Graham's salt) containing 12-14 P atoms in the molecule.

US 4 101 455 (Procter & Gamble/Carson) discloses low phosphate detergent compositions built with a mixture of ortho- and pyrophosphate (10-15 wt%) and tripolyphosphate (7-17 wit), and comprising 0.5-2.5 t of glassy phosphate (n=14-24) which gives improved antiredeposition properties.

The sodium polymer phosphates specifically disclosed in the prior art are water-soluble and in the form of glassy non-crystalline solids; indeed, the term "glassy phosphate" is also frequently used as a generic term for the (sodium) higher condensed phosphates, and as a synonym for Graham's salt. The glassy sodium salts are hygroscopic and are therefore not ideally suited for incorporation in detergent compositions, because of lack of storage stability under damp conditions. Higher sodium salts are obtainable in crystalline form but those are too water-insoluble for detergents use. The potassium salts are crystalline and non-hygroscopic but insoluble in water and have not, therefore, been hitherto been seriously considered as possible useful ingredients for detergent compositions.

It has now been discovered that the crystalline, water-insoluble potassium salts are sufficiently solubilised by the presence of sodium ions to be useful detergent ingredients; provided that the remaining ingredients of the composition can supply sufficient sodium ions in the wash liquor, the potassium salts will dissolve and give useful detergency and antiredeposition benefits. Because of their crystallinitv and non-hygroscopicity they do not impart poor storage properties to a detergent composition. Benefits are particularly observed in detergent compositions built with substantial levels of sodium tripolyphosphate and/or sodium carbonate.

DEFINITION OF THE INVENTION The present invention accordingly provides a detergent composition comprising at least one deterent-active material and and at least one water-soluble builder salt in sodium salt form, and further comprising at least 0.1 wt% of a alkali metal polymer phosphate salt having the formula M2O (MPO3) n wherein M is an alkali metal and n is an integer of at least 4, the alkali metal polymer phosphate salt being crystalline and at least partially in potassium salt form.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to detergent compositions which comprise three specified ingredients - detergent-active materials, water-soluble detergency builders, and alkali metal polymer phosphates - and which may additionally contain any other conventional detergent components. The invention is especially, but not exclusively, applicable to detergent compositions in powder or granular form.

The alkali metal polymer phosphate salt The alkali metal polymer phosphate salt is preferably present in an amount of from 0.1 to 50 wt% of the composition, more preferably from 0.1 to 25 wt%.

The lower levels are effective to improve antiredeposition properties, and are appropriate when substantial amounts of other detergency builders are present; while the higher levels are appropriate if the polymer phosphate itself is intended to make a substantial contribution to detergency building.

The alkali metal polymer phosphate salt suitably has an n-value within the range of from 4 to 400.

Especially preferred are materials having n-values above 30, and more especially from 30 to 150. Materials having n-values of 37, 90, 115, 212 and 362 have all been successfully prepared and tested for their kaolin soil suspension properties.

The salts are conveniently in 100% potassium salt form. Potassium polymer phosphates may readily be synthesised in a range of molecular weights by heating potassium hydrogen phosphate, doped with small amounts of dipotassium hydrogen phosphate to increase the K:P ratio 0 above 1, at temperatures of about 400 C. The K:P ratio is preferably about 1.001 to 1.65. The salts may be characterised by X-ray diffraction (D E C Cambridge and J Lowe, J Chem Soc 493 4555 (1954)) and by FTIR (D E C Cambridge and J Lowe, J Anal Chem 1383 (1955)).

The n-value may be determined by end-point titration (J R Van Wazer, E J Griffith and J F McCullough, Analytical Chemistrv 26, 1555 (1954)).

Also of interest are the crystalline mixed sodium/potassium polymer phosphates, having a repeating unit of the formula 3NaPO3.KPO3, but the all-potassium salts are preferred.

The builder salt The detergent compositions of the invention also contain one or more water-soluble builder salts in sodium salt form. Detergency builder salts are well known to the skilled worker. Inorganic water-soluble builders include sodium ortho-, pyro- and tripolyphosphate and sodium carbonate; while organic water-soluble builders include the salts of nitrilotriacetic acid, carboxymethyloxysuccinic acid, citric acid, and oxydisuccinic acid.

Other water-soluble salts not strictly to be regarded as builders, for example, sodium sulphate, sodium silicate, may also be present.

If desired, the detergent compositions of the invention may also contain a water-insoluble builder, for example, crystalline or amorphous sodium aluminosilicate.

This list is not intended to be exhaustive.

Builders and inorganic salts are well-known to the skilled detergent formulator, and many more examples are listed in the literature and in standard textbooks, for example, "The Manufacture of Soaps, Other Detergents and Glycerine" by Edgar Woolhaft, John Wiley, 1985.

The water-soluble builder salt may suitably be present in an amount of from 1 to 80 wt% of the composition. The total amount of builder in the composition preferably amounts to 20 to 80 wt%.

According to a preferred embodiment of the invention, the composition comprises as water-soluble builder salt at least 1 wt% of sodium tripolyphosphate and/or at least 1 wt of sodium carbonate.

One class of preferred compositions according to the invention comprises from 1 to 40 wt%, and more preferably from 20 to 30 wt%, of sodium tripolyphosphate.

Another class of preferred compositions according to the invention comprises from 1 to 70 wt%, more preferably from 5 to 50 wt%, of sodium carbonate.

When sodium carbonate is present as a detergency builder, the composition may advantageously also include a crystallisation seed for calcium carbonate, for example, calcite, suitably in an amount of from 0.1 to 0.5 parts of calcite per part of sodium carbonate.

Compositions according to the invention may also comprise both sodium tripolyphosphate and sodium carbonate, suitably in a total amount within the range of from 10 to 80 wt%, more preferably from 20 to 50 wt%.

The detergent-active material The compositions of the invention may suitably comprise from 2 to 50 wt%, preferably from 5 to 40 wt%, of one or more anionic, nonionic, cationic, amphoteric or zwitterionic detergent-active materials.

Detergent-active materials are well-known to the skilled detergent formulator, and many examples are listed in the literature and in standard textbooks, for example Woolhaft (mentioned above), and "Surface-Active Agents and Detergents" by Schwartz, Perry and Berch.

The preferred detergent-active compounds that can be used are soaps and synthetic non-soap anionic surfactants and nonionic surfactants.

Synthetic anionic surfactants are well known to those skilled in the art. Examples include alkylbenzene sulphonates, especially linear alkylbenzene sulphonates having an alkyl chain length of C8-C15; primary and secondary alkyl sulphates, particularly sodium C12-C15 primary alcohol sulphates; alpha-olefin sulphonates and internal olefin sulphonates; alkane sulphonates; dialkyl sulphosuccinates; and fatty acid ester sulphonates.

Suitable non ionic detergent compounds which may be used include in particular the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example, aliphatic alcohols, acids, amides or alkyl phenols with alkylene oxides, especially ethylene oxide either alone or with propylene oxide.

Specific nonionic detergent compounds are ethoxylated alkyl (cog 22) phenols, ethoxylated linear or branched aliphatic Cog~20 primary or secondary alcohols.

Especially preferred are the primary and secondary alcohol ethoxylates, especially the C12 15 primary and secondary alcohols ethoxylated with an average of from 5 to 20 moles of ethylene oxide per mole of alcohol.

It may also be desirable to include one or more soaps of fatty acids. These are preferably sodium soaps derived from naturally occurring fatty acids, for example, the fatty acids from coconut oil, beef tallow, sunflower or hardened rape seed oil.

Optional ingredients As well as the ingredients already discussed, the compositions of the invention may contain any other non-interfering components known to be suitable for incorporation into detergent compositions. Such components are well-known to the skilled detergent formulator, and are fully described in the literature, for example, the Woolhaft textbook mentioned previously.

Examples of such components include, for example, water-insoluble builders; peroxy bleaches such as sodium perborate or percarbonate, bleach activators such as tetraacetylethylenediamine, bleach stabilisers; lather suppressors or lather boosters as appropriate; antiredeposition agents, for example, sodium carboxymethyl cellulose; anti-incrustation agents; fluorescers; fillers such as clays; sodium silicate; other inorganic salts; enzymes; perfumes; pigments; preservatives; abrasives. This list is not intended to be exhaustive.

According to one preferred embodiment of the invention, the compositions contain a polycarboxylate polymer, preferably a homopolymer or copolymer of acrylic acid and/or maleic acid, or a sodium salt thereof.

Especially preferred polymers are polyacrylic acid and polyacrylates, for example, the Narlex (Trade Mark) series ex National Adhesives and Resins; acrylic phosphinates such as DKW (Trade Mark) 125 ex National Adhesives and Resins; and acrylic/maleic copolymers for example, Sokalan (Trade Mark) CP4 and CP5 ex BASF.

Other suitable polymers are listed in our copending British Patent Application No. 88 21034.9 filed on 7 September 1998 (Case C.3267). These polymers are effective both as builders and as antiredenosition agents, and in combination with the alkali metal polymer phosphate salts used according to the present invention can give synergistic benefits. The polymers are suitably present in amounts within the range of from 0.5 to 5 wt%, preferably from 1 to 3 wt%.

Preparation of detergent compositions Detergent compositions of the invention may be prepared by any suitable method. Detergent powders are suitably prepared by spray-drying a slurry of compatible heat-insensitive components, and then spraying on or postdosing those ingredients unsuitable for processing via the slurry. The skilled detergent formulator will generally have no difficulty in deciding which components should be included in the slurrv and which should be postdosed or sprayed on.

Alkali metal polymer phosphates are preferably not included in the slurry because some decomposition to lower phosphates can occur at slurry-processing and spray-drying temperatures. The preferred method for incorporating these salts is hy dry-mixing.

Thus, spray-dried powders in accordance with the invention are preferably prepared by admixing the alkali metal polymer phosphate, and other heat-sensitive or slurry-incompatible ingredients, to a spray-dried base powder.

Of course, detergent powders in accordance with the invention may also be prepared by wholly non-tower methods, for example, dry mixing. The alkali metal polymer phosphate may be admixed at any suitable stage in the process with some or all of the other ingredients of the composition.

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

EXAMPLES Examples 1 & 2 A detergent powder (Comparative Example A) was prepared by spray-drying and postdosing, and two compositions in accordance with the present invention (Examples 1 and 2), were prepared by addinq respectively 5 wt% and 10 wt% of a potassium polymer phosphate (n = 90, R/P ratio 1.01) to this powder.The percentage compositions of the powders of the three powders were as follows: 1 2 A Linear alkylbenzene sulphonate 19.1 18.2 20.0 Sodium tripolyphosphate 20.9 20.0 22.0 Sodium carbonate 9.5 9.1 10.0 Sodium silicate 9.5 9.1 10.0 Sodium sulphate 10.8 10.3 11.3 Calcite 4.8 4.6 5.0 Sodium carboxymethyl cellulose 1.9 1.8 2.0 Minor ingredients 3.5 3.2 3.7 Moisture 15.2 14.6 16.0 K polymer phosphate 4.8 9.1 100.0 100.0 100.0 Antiredeposition assessment was carried out by means of the following procedure, three replicate experiments being carried out for each detergent composition.Clean desized cotton monitors, together with naturally soiled pieces of the same fahric, in a 1:1 weight ratio, were soaked for 30 minutes in a wash liquor consisting of 0.7 0 wt% of the detergent composition under test in 24 FH water (2:1 Ca:Mg) at ambient temperature, then rinsed four times in water of the same hardness; the wash/rinse cycle was carried out three times, a fresh soiled load being used for each cycle. Reflectance (R460*) of the cotton monitors was measured before the first cycle, and after the third cycle: the reduction in reflectance indicates the amount of redeposition that occurred.The results for Examples A and 1 were as follows, showing the benefit of including the polymer phosphate salt in Example 1: A 1 Reflectance change ( R460*) -6.51 -3.98 after three cycles Detergency was assessed by means of the following procedure, in accordance with Indian Standards 5785 Part V (1976). Clean desized cotton monitors were artificially soiled with a mixed triolein/oleic acid/liquid paraffin/ carbon tetrachloride soil, then washed in the Tergotometer for 15 minutes in a wash liquor consisting of 0.7 wt% of the detergent composition under test in 240FH water (2:1 Ca:Mg) at ambient temperature, then rinsed once in water of the same hardness.Reflectance (R460*) of the cotton monitors was measured before and after the wash/rinse cycle, and percentage detergency was calculated by means of the following equation: % detergency = Rw R R5 x 100 w s R - R c s wherein Rw = detergency of clean cloth, R5 = reflectance of soiled cloth, and Rw = detergency of soiled cloth after washing. Two replicate experiments were carried out for each detergent composition.

The results for Examples A, 1 and 2 were as follows: A 1 2 Detergency (%) first wash 10.0 12.4 13.2 second wash 13.0 14.1 15.1 These results clearly show the detergency benefits of including a polymer phosphate salt in accordance with the invention in a detergent composition built with a substantial level of sodium tripolyphosphate and also containing a moderate level of sodium carbonate.

Example 3 A detergent powder (Comparative Example B) was prepared by spray-drying and postdosing, and a composition in accordance with the present invention (Example 3) was prepared by adding 10 wt% of the potassium polymer phosphate used in Examples 1 and 2 to this powder. The percentage compositions of these two powders were as follows: B 3 Linear alkylbenzene sulphonate 17.0 15.5 Sodium tripolyphosphate 2.0 1.8 Sodium carbonate 25.0 22.7 Sodium silicate 8.0 7.3 Sodium sulphate 27.0 24.5 Calcite 6.0 5.5 Sodium carboxymethyl cellulose 1.0 0.9 Minor ingredients 5.0 4.5 Moisture 9.0 8.2 K polymer phosphate - 9.1 100.0 100.0 Detergency was assessed as described above in Examples 1 and 2, and the results were as follows: : B 3 Detergency (z) first wash 8.1 9.9 second wash 10.5 12.0 These results clearly show the detergency benefits of including a polymer phosphate salt in accordance with the invention in a detergent composition containing a substantial level of sodium carbonate and a low level of sodium tripolyphosphate.

Claims

1. A detergent composition comprising at least one detergent-active material and and at least one water-soluble builder salt in sodium salt form, and further comprising at least 0.1 wtt of a alkali metal polymer phosphate salt having the formula M2O-(MPO3)n wherein M is an alkali metal and n is an integer of at least 4, the alkali metal polymer phosphate salt being crystalline and at least partially in potassium salt form.

2. A detergent composition as claimed in claim 1, which comprises from 0.1 to 50 wtZ of the alkali metal polymer phosphate salt.

3. A detergent composition as claimed in claim 2, which comprises from 0.1 to 25 wt% of the alkali metal polymer phosphate salt.

4. A detergent composition as claimed in any preceding claim, wherein the alkali metal polymer phosphate salt has an n-value within the range of from 4 to 400.

5. A detergent composition as claimed in claim 4, wherein the alkali metal polymer phosphate salt has an n-value within the range of from 30 to 150.

6. A detergent composition as claimed in any preceding claim, wherein the alkali metal polymer phosphate salt is wholly in potassium salt form.

7. A detergent composition as claimed in any preceding claim, which comprises from 1 to 80 wt% of one or more detergency builder salts in sodium salt form.

8. A detergent composition as claimed in claim 7, which comprises as water-soluble builder salt at least 1 wt% of sodium tripolyphosphate.

9. A detergent composition as claimed in claim 8, which comprises from 1 to 40 wt% of sodium tripolyphosphate.

10. A detergent composition as claimed in claim 9, which comprises from 20 to 30 wt% of sodium tripolyphosphate.

11. A detergent composition as claimed in any preceding claim, which comprises as water-soluble builder salt at least 1 wt% of sodium carbonate.

12. A detergent composition as claimed in claim 11, which comprises from 1 to 70 wt% of sodium carbonate.

13. A detergent composition as claimed in claim 12, which comprises from 5 to 50 wt% of sodium carbonate.

14. A detergent composition as claimed in any one of claims 8 to 13, which comprises both sodium tripolyphosphate and sodium carbonate in a total amount within the range of from 10 to 80 wt%.

15. A detergent composition as claimed in claim 14, which comprises both sodium tripolyphosphate and sodium carbonate in a total amount within the range of from 20 to 50 wt%.

16. A detergent composition as claimed in any preceding claim, which further comprises a polycarboxylate polymer selected from homopolymers and copolymers of acrylic acid and/or maleic acid, and their sodium salts.

17. A detergent composition as claimed in claim 16, wherein the polycarboxylate polymer comprises polyacrylic acid, a polyacrylate, an acrylic phosphinate, or an acrylic/maleic copolymer.

18. A detergent composition as claimed in claim 16 or claim 17, wherein the polycarboxylate polymer is present in an amount within the range of from 0.5 to 5 wt%.

19. A detergent composition as claimed in any one of claims 16 to 18, wherein the polycarboxylate polymer is present in an amount within the range of from 1 to 3 wt%.

20. A detergent composition as claimed in any preceding claim, wherein the detergent-active material is selected from anionic, nonionic, cationic, amphoteric or zwitterionic detergent-active materials and mixtures thereof, and is present in an amount of from 5 to 40 wt%.

21. A detergent composition as claimed in any preceding claim, prepared by a process in which the alkali metal polymer phosphate salt is dry-mixed with other components of the composition.

22. A detergent composition substantially as hereinbefore described in any one of Examples 1 to 3.

Amendments to the claims have been filed as follows CLAIMS 1. A detergent composition comprising at least one detergent-active material and and at least one water-soluble builder salt in sodium salt form, and further comprising at least 0.1 wt% of a alkali metal polymer phosphate salt having the formula M2O- (MPO3) n wherein M is an alkali metal and n is an integer of at least 4, the alkali metal polymer phosphate salt being crystalline and at least partially in potassium salt form.

2. A detergent composition as claimed in claim 1, wherein the alkali metal polymer phosphate salt has an n-value within the range of from 4 to 400.

3. A detergent composition as claimed in claim 1 or claim 2, wherein the alkali metal polymer phosphate salt has an n-value of at least 30.

4. A detergent composition as claimed in claim 3, wherein the alkali metal polymer phosphate salt has an n-value within the range of from 30 to 150.

5. A detergent composition as claimed in any preceding claim, which comprises from 0.1 to 50 wt% of the alkali metal polymer phosphate salt.

6. A detergent composition as claimed in claim 5, which comprises from 0.1 to 25 wt% of the alkali metal polymer phosphate salt.

7. A detergent composition as claimed in any preceding claim, wherein the alkali metal polymer phosphate salt is wholly in potassium salt form.

8. A detergent composition as claimed in any preceding claim, which comprises from 1 to 80 wt% of one or more detergency builder salts in sodium salt form.

9. A detergent composition as claimed in claim 8, which comprises as water-soluble builder salt at least 1 wt% of sodium tripolyphosphate.

10. A detergent composition as claimed in claim 9, which comprises from 1 to 40 wt% of sodium tripolyphosphate.

11. A detergent composition as claimed in claim 10, which comprises from 20 to 30 wt% of sodium tripolyphosphate.

12. A detergent composition as claimed in any preceding claim, which comprises as water-soluble builder salt at least 1 wt% of sodium carbonate.

13. A detergent composition as claimed in claim 12, which comprises from 1 to 70 wt% of sodium carbonate.

14. A detergent composition as claimed in claim 13, which comprises from 5 to 50 wt% of sodium carbonate.

15. A detergent composition as claimed in any one of claims 9 to 14, which comprises both sodium tripolyphosphate and sodium carbonate in a total amount within the range of from 10 to 80 wt%.

16. A detergent composition as claimed in claim 15, which comprises both sodium tripolyphosphate and sodium carbonate in a total amount within the range of from 20 to 50 wt%.

17. A detergent composition as claimed in any preceding claim, which further comprises a polycarboxylate polymer selected from homopolymers and copolymers of acrylic acid and/or maleic acid, and their sodium salts.

18. A detergent composition as claimed in claim 17, wherein the polycarboxylate polymer comprises polyacrylic acid, a polyacrylate, an acrylic phosphinate, or an acrylic/maleic copolymer.

19. A detergent composition as claimed in claim 17 or claim 18, wherein the polycarboxylate polymer is present in an amount within-the range of from 0.5 to 5 wt%.

20. A detergent composition as claimed in any one of claims 17 to 19, wherein the polycarboxylate polymer is present in an amount within the range of from 1 to 3 wt%.

21. A detergent composition as claimed in any preceding claim, wherein the detergent-active material is selected from anionic, nonionic, cationic, amphoteric or zwitterionic detergent-active materials and mixtures thereof, and is present in an amount of from 5 to 40 wt%.

22. A detergent composition as claimed in any preceding claim, which is in powder or granular form.

23. A detergent composition as claimed in claim 22, prepared by a process in which the alkali metal polymer phosphate salt is dry-mixed with other components of the composition.

24. A detergent composition substantially as hereinbefore described in any one of Examples 1 to 3.