US 3370015 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
United States Patent Ofitlce Patented Feb. 20, 1968 3,370,015 PROCESS FOR PREPARING DETERGENT CUB/[POSITIONS Daniel Marten van Kampen and Frederick Johan Kerkhoven, Vlaardingen, and Willem van der Star, Rotterdam, Netherlands, assignors to Lever Brothers Company, New York, N.Y., a corporation of Maine No Drawing. Filed Jan. 30, 1964, Ser. No. 341,419
9 Claims. (Cl. 252137) ABSTRACT OF THE DISCLOSURE This disclosure is concerned with forming a strong, fast-dissolving detergent tablet. In this disclosure, a hydrated condensed phosphate is added to a detergent prior to compression into a tablet.
Detergent tablets are already known, but the production of such tablets requires very special measures as regards selecting the components of the tablet and working up these components into the final detergent tablet. Consequently, the production of detergent tablets is a complex matter. It involves even more than the mere selection of the components or the compression of a particulate detergent composition into a tablet: the tablet must be capable of withstanding the shocks of packing, handling and distribution without crumbling. In other words, the tablet must be strong. Besides, the tablet must have a satisfactory rate of disintegration when put in water. The tablets known so far have generally shown too long a disintegration time, in favour of their strength, or they have had a very low strength, in favour of their disintegration time.
It is therefore the object of the present invention to provide detergent tablets which do not have the abovementioned disadvantages, but which on the contrary are strong and yet disintegrate quickly when put in water.
It is another object of the invention to provide a simple and cheap process for producing detergent tablets having the aforesaid highly desirable properties.
It has surprisingly been found that detergent tablets which are strong and yet disintegrate quickly in water can be. prepared by simply incorporating one or more partially or completely hydrated condensed phosphates in particulate form into a mixture of detergent components which is in the dry, particulate state, after which the particulate mass obtained is compressed into tablets.
Preferably, completely hydrated condensed phosphates are used, but good results are also obtained with partially hydrated condensed phosphates. It has even appeared to be possible to obtain satisfactory results by using partially hydrated condensed phosphates having a degree of hydration as low as 30%. However, when partially hydrated condensed phosphates are used, optimal results are achieved with condensed phosphates that have been bydrated for at least 60%.
The present invention must therefore be seen in that by using one or more partially (preferably for at least 60%) or completely hydrated condensed phosphates detergent tablets are obtained which are strong and yet disintegrate quickly in water.
Examples of such hydratable condensed phosphates are penta-sodium tripolyphosphate, which may form a hexahydrate, and tetra-sodium pyrophosphate, which may form a decahydrate. As already stated above, if partially hydrated condensed phosphates are used, they must preferably have been hydrated for at least 60%. This means that if penta-sodium tripolyphosphate is used, 60% of this salt should be in the hexahydrate form, and in the case of tetra-sodium pyrophosphate 60% of this salt should be in the decahydrate form. It is the very advantage of the process according to the present invention that in this way any commercially available hydratable condensed phosphate can be used for the preparation of satisfactory detergent tablets, Whereas according to the prior art satisfactory detergent tablets could only be obtained so far with very special and rather expensive condensed phosphates. These known phosphates are completely anhydrous, i.e. they contain less than 1% moisture.
According to the present invention the particulate state of the hydrated condensed phosphates does not in principle affect the favourable properties of the detergent tablet with respect to strength and disintegration time. Optimal results, however, are obtained by using fine phosphates. In that case the fineness of the phosphates is pref erably smaller than 200 The amount of hydrated condensed phosphates necessary for imparting the desired properties to the detergent tablets is empirically established. In general the tablet should have a content of hydrated condensed phosphates of at least 15% based on the total weight of the tablet; preferably this content should vary between 40-60% by Weight of the tablet.
The partially or completely hydrated condensed phosphates may be prepared in any conventional manner. A simply and highly satisfactory method is to spray the predetermined quantity of water by means of any suitable fine spray producing device onto the surface of a given bulk of an anhydrous commercially available hydratable condensed phosphate, while the latter is being kept in agitation in a mixture. The hydrated condensed phosphate may also be formed previously by spraying on the anhydrous salt an aqueous solution of a component of the detergent composition, such as e.g. the active detergent or a silicate. Care should of course be taken that the amount of water present in the solution is such that the resulting hydrate is in a dry, particulate state, which hydrate is then mixed with the bulk of the detergent composition, which is also in a dry, particulate state.
The detergent composition in particulate form, in which the partially or completely hydrated condensed phosphates are incorporated, may be of any kind commonly used in practice. They may contain in any suitable proportion one or more organic synthetic surface-active agents, such as anionics and/or nonionics- Also soaps may be used. They may further contain builders, fillers and normal adjuvant material, such as soil-suspending agents, perfumes, foaming agents, foam stabilizers, whiteners, etc., as well as bleaching agents. Examples of the anionics are alkylaryl sulphonates, alkyl sulphates, condensation products of fatty acids with isethionates or methyl taurine; examples of nonionics are fatty alcohols condensed with ethylene oxides, alkyl phenols condensed with ethylene oxide, etc. As builders may be used silicates and/or sodium salts of ethylene diamine tetraacetic acid. As a filler sodium sulphate may be chosen, while eg sodium perborate may be used as a bleaching agent.
The total amount of one or more active detergents present in the detergent tablet varies from 5 to 30% by weight and is preferably between about 15 and 25% by weight of the tablet.
The ratio between the amounts of phosphate or phosphates and active detergent or detergents is more or less critical in order to obtain detergent tablets that have both a satisfactory strength and a satisfactory disintegration time. If the weight ratio of phosphate or phosphates to active detergent or detergents lies within the range of about 2:1 to 25:1, tablets are obtained which fulfil the aforesaid conditions.
In general, on carrying out the process of the invention, the components of the detergent composition to be preparedi.e. without the phosphates-can be mixed in a dry state in any desired sequence and in such a way that a dry, particulate mass is obtained. To this mixture the required amount of one or more partially or completely hydrated condensed phosphates in dry form is added and thoroughly mixed. The mixture thus obtained is then compressed into a tablet of any suitable form, such as cylindrical, hexagonal, square, cylindrical with truncated faces, etc. Tablets prepared in this Way have a much higher rate of disintegration in water than equally strong tablets containing anhydrous condensed phosphates.
The invention will now be illustrated by means of the following examples:
Example 1 A dry detergent composition was prepared by mixing the following components:
Parts Sodium tetrapropylene benzene sulphonate 5 Nonyl phenol condensed with 11 moles ethylene oxide 2.5 Tallow fatty alcohol condensed with 50 moles ethylene oxide 1.5 Sodium soap (100%) 5 Sodium silicate (Na O:SiO =1:2) 8.7 Sodium sulphate anh. 16.8 Sodium carboxy methylcellulose (100%) 0.5 Brighteners 0.11 Perfume 0.08 Sodium perborate 10 58 parts of this composition were mixed with 42 parts of a specific commercially available anhydrous penta- 30 sodium tripolyphosphate and the mixture thus obtained was compressed into a tablet of cylindrical form with truncated faces having a diameter of 57 mm., a thickness of 24 mm. and a weight of 50 grammes. In this manner three types of tablets were prepared, each containing a commercial anhydrous penta-sodium tripolyphosphate (STPP) originating from a different manufacturer, viz. Marchon, E.N.C.K. and Kuhlmann, respectively.
In the same way and with the same detergent composition another series of three tablets was prepared, which 4 tablets were consequently identical to those mentioned before, except in that the tablets of this second series contained the commercial penta-sodium tripolyphosphate in the completely hydrated form. Each of the dry detergent mixtures was compressed to such an extent that the finally obtained tablets had a fracture strength of 6 kg. This fracture strength was determined in the following way: A tablet was placed on its edge on a plate resting on a scale graduated in kilogrammes. A top plate was gradually forced down onto the tablet until it broke, at which point the number of kilogrammes was read from the scale, this reading being a measure for the fracture strength of the tablets.
For each tablet the disintegration time was determined as follows: A tablet of 50 grammes Was placed in a transparent plastic cage perforated on all sides. The cage was moved up and down with a frequency of 90 times per minute in a bucket containing 15 litres of tap water at a temperature of 50 C. The tablet was observed and the time necessary for complete disintegration measured. The following table gives the data thus obtained regarding the disintegration time of each of the tablets containing a specific penta-sodium tripolyphosphate in the anhydrous form as compared with the disintegration time of each of the tablets containing the specific penta-sodium tripolyphosphate in the completely hydrated form.
[Disintegration times at 50 C. at a fracture strength of 6 kg.]
From this table it will be clearly seen that the use of hydrated condensed phosphates in detergent tablets considerably reduces the disintegration times of these tablets. The content of STPP ex-Kuhlmann in the tablets was 42% by weight. If this content was decreased to 19%, the
disintegration times measured for tablets containing anhydrous and completely hydrated STPP, respectively, were 275 sec. and 130 sec., respectively. The difference between these disintegration times was reduced to nil in case the phosphate content was decreased to 9% by weight of the tablets; for both types of tablets the disintegration time then was 190 seconds.
Example 2 Two series of tablets were prepared based on a formula identical to that according to Example 1, with the exception that instead of penta-sodium tripolyphosphate tetra-sodium pyrophosphate (TSPP) was used. Two series of tablets were prepared, one containing anhydrous tetra- 20 sodium pyrophosphate and the other containing this phosphate in completely hydrated form, by compressing the dry detergent mixture until the tablets had a fracture strength of 6 kg. The disintegration times at 50 C. of these tablets were:
Anhydrous Completely Tablet with- TSPP, sec. hydrated TSPP, sec.
Tetra-sodium pyrophosphate ex ENCK. 600 80 This comparative experiment was repeated by using anhydrous TSPP and TSPP which had been hydrated for 60% respectively. This resulted in disintegration times of 600 sec. and 150 sec., respectively.
Example 3 The same method was applied as in Example 1, but this time a dry detergent mixture was made of the following composition:
Parts Sodium tetra propylene benzene sulphonate (82% AD.) 19.5 Coconut ethanolamide 4.0 Sodium carboxy methylcellulose (60%) 1.67 Sodium silicate (Na O:SiO =l:2) spray-dried 7.5 Sodium perborate 8.0
Anhydrous Completely Tablets with- STPP, see. hydrated STPP, sec.
Penta-sodium tripolyphosphate ex Marchon 900 7O Penta-sodium tripolyphosphate ex ENCK 900 80 Petite-sodium tripolyphosphate ex Kuhlmann 900 50 Also this table clearly shows the considerable reduction in disintegration time obtained with hydrated condensed phosphates.
Example 4 Two tablets were prepared from a detergent composition identical to that according to Example 1. Both tablets were made by compressing the dry detergent mixture until a fracture strength of 6.3 kg. was obtained. One tablet contained anhydrous penta-sodium tripolyphosphate, the other containing penta-sodium tripolyphosphate which had been hydrated for 60%. The following disintegration times were determined at 50 C.:
Anhyd ous Completely Tablet with- STPP, sec. hydrated STPP, see.
Penta-sodium tripolyphosphate ex ENCK 480 75 This table clearly shows the improvement obtained by using partially, i.e. for at least 60%, hydrated condensed phosphate.
Example 5 The following tables show the comparative disintegration times of tablets prepared according to Example 1, but with different fracture strengths. The detergent composition was the same as in Example 1, but the mixture was compressed until tablets were obtained having a fracture strength of 4 and 8 kg., respectively.
[Disintegration times at 50 C. of 1gatilets having a fracture strength of8 g.
Anhydrous Completely Tablets with- STPP, see. hydrated STPP, sec.
Penta-sodium tri ol hos hate ex Marehon HPHK LHR 900 180 Penta-sodium tripolyphosphate ex ENCK 750 130 Penta-sodium tripolyphosphate ex Kuhl- Example 6 Two series of tablets were prepared based on a formula identical to that according to Example 1, with the exception that instead of STPP a mixture of STPP and TSPP was used. Two series of tablets were prepared, one containing 42% by weight of a mixture of equal quantities of the phosphates in anhydrous form, and the other containing 42% by weight of a mixture of these phosphates, calculated on the anhydrous phosphates, each of which was in the completely hydrated form, by compressing the dry detergent mixture until the tablets had a fracture strength of 6 kg. The disintegration times at 50 C. of these tablets were as follows:
What is claimed is:
1. A process for preparing a detergent tablet which comprises forming a dry, particulate detergent, said detergent being selected from the group consisting of an anionic detergent, nonionic detergent or mixtures thereof; forming separately a dry, particulate phosphate which has been hydrated between about and said phosphate being pentasodium tripolyphosphate, tetrasodium pyrophosphate or mixtures thereof; adding said phosphate to said detergent to obtain a mixture having a weight ratio of phosphate to detergent of about 2:1 to 25: 1; and compressing said dry mixture at a pressure suflicient to provide a detergent tablet which is strong and which disintegrates quickly when placed in water.
2. The process according to claim 1 in which the detergent is an anionic detergent which is selected from the group consisting of an alkyl aryl sulphonate, an alkyl sulphate, a condensation product of a fatty acid with an isethionate and a condensation product of a fatty acid with methyl taurine.
3. The process according to claim 1 in which the detergent is an nonionic detergent which is selected from the group consisting of a fatty alcohol condensed with ethylene oxide and an alkyl phenol condensed with ethylene oxide.
4. The process according to claim 1 in which the dry phosphate has been partially hydrated to about 60%.
5. The process according to claim 1 in which the dry phosphate has been completely hydrated.
6. The process according to claim 1 in which the amount of phosphate is about 15% to 60% and the amount of detergent is about 5% to 30% by weight of the tablet.
7. The process according to claim 1 in which the dry admixture is compressed at a pressure sufficient to provide a fracture strength between about 4 and 8 kg. in the detergent tablet without further hydration.
8. The process according to claim 1 in which the phosphate is pentasodium tripolyphosphate.
9. The process according to claim 1 in which the phosphate is tetrasodium pyrophosphate.
References Cited UNITED STATES PATENTS 2,875,155 2/1959 Miles 252138 3,081,267 3/1963 Laskey 252- 3,172,859 3/1965 Percival et al. 252137 3,240,712 3/1966 Schulerud et al 252138 3,247,122 4/1966 Schaafsma et al. 252138 3,247,123 4/1966 Schrager et al. 252135 LEON D. ROSDOL, Primary Examiner.
A. T. MEYERS, B. BETTIS, Assistant Examiners.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,370,015 February 20, 1968 Daniel Marten Van Kampen et a1.
It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.
Column 5, line 3, for "Completely" read Partially line 54, for "wlth" read with Signed and sealed this 20th day of May 1969.
Edward M. Fletcher, Jr.
Attesting Officer Commissioner of Patents