EP1239026A1

EP1239026A1 - Detergent tablets

Info

Publication number: EP1239026A1
Application number: EP02251321A
Authority: EP
Inventors: Huug c/o Lever Fabergé Europe - Dev.Centre Euser; Alan Digby c/o Lever Fabergé Europe Tomlinson
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2001-03-05
Filing date: 2002-02-26
Publication date: 2002-09-11
Anticipated expiration: 2022-02-26
Also published as: EP1239026B1

Abstract

A detergent tablet comprising:

a) a solid hydrocarbon polyether,

b) a colouring agent and;

c) a hydratable acid or salt thereof,
and the use thereof for cleaning utensils within a mashine dishwasher.

Description

The present invention is in the field of detergent tablets. More specifically, the invention encompasses automatic dishwashing tablets, and a process for preparing them.
Machine dishwashing tablets are popular with the consumer as they have several advantages over powdered products in that they do not require measuring, and they are compact and easy to store.
Aesthetically it is pleasing if a tablet has a glossy coloured appearance. However, we have had difficulties in producing a coloured, glossy tablet as on storage the colour of the tablet fades.
The present invention provides tablets which are aesthetically pleasing, in that they have a glossy appearance and are coloured. The colour of the tablet does not fade on storage.
Thus, according to a first aspect of the invention, there is provided a detergent tablet comprising:
a) a solid hydrocarbon poly ether,
b) a colouring agent and;
c) a hydratable acid or salt thereof.
Also described is the use of a tablet according to the invention for cleaning utensils and kitchenware within a machine dishwasher.
The tablets of the invention may be in any form suitable for addition to a washing or dish washer machine.
The colouring agent is a dye or a pigment; it is preferable if it is a dye.
Tablets of this invention may consist of only one phase, in that they are produced by compaction of a single particulate composition. In such a case the whole tablet is coloured with a glossy surface.
However, this invention is particularly relevant to tablets having two or more phases. The compositions according to the invention can be used for some but not all of the phases, such that different phases have different colours and different textures.
It is particularly preferred if the tablet of the invention is a triple phase tablet, the phases being in the form of layers. It is highly preferable if the centre layer comprises the formulation of the invention, in that it comprises a solid hydrocarbon poly ether, a hydratable salt and a colouring agent.
It is preferred if the tablet has a strength of from 50 to 300 newtons (N) as measured on a MTS Synergie 100 using a loadcell of 500 N maximum capacity, the initial and secondary crosshead speeds being set at 25 mm/min, with a deformation limit of 200%.
The tablets of the invention preferably have a mass of greater than 8g, more preferably from 12g to 30g, most preferably 15g to 27g. Tablets with a mass of 20g, 22g or 25g are particularly useful.
Preferably, the tablets are prepared from dense powder. If the tablet has a plurality of layers, it is preferred if each of the layers are compacted in a mould. When the final layer is added, compaction pressure is applied to the entire tablet.
The solid hydrocarbon ether used in the tablets of the present invention has a softening or melting temperature above 25°C, preferably at least 35°C. Preferably the melting temperature is not greater than 80°C.
It is desirable if the solid hydrocarbon polyether is an alkoxylated alkyl ether; particularly desirable are polyethylene glycols. Polyethylene glycols having a molecular weight from 1500 to 10,000 are preferred, more preferably 3000 to 8000.
The total level of solid hydrocarbon poly ether in the tablet is from 5 wt% to 20 wt% of the total weight of the tablet, more preferably from 7 wt% to 15 wt%. of the total weight of the tablet.
If the solid hydrocarbon is present in a multiphase tablet, it is preferable if at least 60 wt% of the solid hydrocarbon ether is in a single phase, more preferably 75 wt% of the hydrocarbon ether, most preferably at least 90wt% of the hydrocarbon ether. If the tablet is a triple layer tablet, it is preferable if the ratios cited in the preceding sentence apply to the middle layer.
By the term "hydratable salt" it is meant that the salt is in a state in which it may absorb additional water by hydration. That is to say that the salt is present either in its anhydrous form, or in a partially hydrated form.
The hydratable salt is preferably particulate in nature and may, for example, be alkali metal carbonate, bicarbonate, (poly) phosphate, citrate (anhydrous) or sulfate. Mixtures of two or more hydratable compounds may also be used, but preferably sodium tripolyphosphate is used.
Compositions of the invention preferably comprise a water-soluble phosphate; typically this phosphate is contained at a level of from 1% to 90% by weight, preferably from 10% to 80% by weight, most preferably from 20% to 80% by weight of the composition. Specific examples of water-soluble phosphates are the alkali metal tripolyphosphates, sodium, potassium and ammonium pyrophosphate, sodium and potassium orthophosphate, sodium polymeta/phosphate in which the degree of polymerization ranges from about 6 to 21, and salts of phytic acid. Sodium or potassium tripolyphosphate is most preferred.
In a preferred composition sodium tripolyphosphate with high Phase I Content is used.
Sodium tripolyphosphate with high Phase I can be prepared by heating to above the transition temperature at which phase II anhydrous sodium polyphosphate is transformed into the phase I form. A process for the manufacture of particles containing a high proportion of the phase I form of sodium tripolyphosphate by spray drying below 420°C is given in US-A-4536377.
Suitable material is commercially available. Suppliers include Rhodia, Courbevoie, France and Albright & Wilson, Warley, West Midlands, UK. The sodium tripolyphosphate should be partially hydrated, but the phase I anhydrous form should also be present. Thus, the sodium tripolyphosphate in the particles may incorporate up to 5% (by weight of the sodium tripolyphosphate in these particles) of water of hydration. The extent of hydration is desirably from 1% to 4% or 5% by weight. This degree of hydration in general means that the sodium tripolyphosphate is partially hydrated.
The sodium tripolyphosphate in these particles is preferably hydrated by a process which leads to a homogeneous distribution of the water of hydration within the tripolyphosphate.
The bulk density of the of sodium tripolyphosphate particles is preferably 0.75 kg/litre or less, more preferably from 0.52 to 0.72 kg/litre.
The particles which contain or consist of sodium tripolyphosphate preferably have a small mean particle size, such as not over 300µm, better not over 250µm. Small particle size can if necessary be achieved by grinding.
Uniform prehydration, high phase I content, porosity and small particle size all promote rapid hydration when the tripolyphosphate comes into contact with water. A standard test for the rapidity of hydration is the Olten test. It is desirable that in such a test the tripolyphosphate reaches 90% of the final value (i.e. 90% of complete hydration when exposed to water at 80°C) within 60 seconds.
"Rhodiaphos HPA 3.5" is a grade of sodium tripolyphosphate from Rhodea which has been found to be particularly suitable. It consists of porous particles of small particle size (mean size below 250µm) with 70% phase I and prehydrated with 3.5% water of hydration.
Preferably the said particles containing sodium tripolyphosphate with more than 40% of phase I material.
A further preferred embodiment is a mixture of phase II and phase I sodium tripolyphaspate, preferably in the ratio of 6:4 to 4:6 of phase I to phase II.
It is preferable if the tablet has more than one phase that from 10 wt% to 30 wt% of the total level of phosphate present in the tablet is present in the phase comprising the higher level of solid hydrocarbon ether.
The compositions of the invention may contain a non-hydratable builder in addition to the hydratable salt.
However if the hydratable builder and the hydrable salt are present in a single-phase tablet of in the same phase, it is preferred if the ratio of hydratable salt to non-hydratable builder is at least 2:1, more preferably 3:1.
If the tablet has at least two phases, it is preferable if the non-hydratable builder is present in a separate phase to the solid hydrocarbon polyether, especially if the solid hydrocarbon polyether is a polethylene glycol.
The non-hydrable builder is preferably present from 1% to 50% by weight, more preferably from 5% to 30% by weight of the composition. Suitable examples of non-phosphorus containing inorganic builders include water-soluble alkali metal, borates, and silicates, including layered silicates such as SKS-6 ex. Hoechst, metasilicates, crystalline and amorphous aluminosilicates, and silicates including layered silicates and zeolites.
Organic detergent builders can also be used as nonphosphate builders in the present invention. Examples of organic builders include alkali metal citrates, succinates, malonates, fatty acid sulfonates, fatty acid carboxylates, nitrilotriacetates, oxydisuccinates, alkyl and alkenyl disuccinates, oxydiacetates, carboxymethyloxy succinates, ethylenediamine tetraacetates, tartrate monosuccinates, tartrate disuccinates, tartrate monoacetates, tartrate diacetates, oxidized starches, oxidized heteropolymeric polysaccharides, polyhydroxysulfonates, polycarboxylates such as polyacrylates, polymaleates, polyacetates, polyhydroxyacrylates, polyacrylate/polymaleate and polyacrylate/ polymethacrylate copolymers, acrylate/maleate/vinyl alcohol terpolymers, aminopolycarboxylates and polyacetal carboxylates, and polyaspartates and mixtures thereof. Such carboxylates are described in U.S. Patent Nos. 4,144,226, 4,146,495 and 4,686,062. Alkali metal citrates, nitrilotriacetates, oxydisuccinates, acrylate/maleate copolymers and acrylate/maleate/vinyl alcohol terpolymers are especially preferred nonphosphate builders.
The composition optionally comprises alkali metal silicates.
When silicates are present, the SiO₂ level should be from 1% to 25%, preferably from 2% to 20%, more preferably from 3% to 10%, based on the weight of the ADD. The ratio of SiO₂ to the alkali metal oxide (M₂0, where M = alkali metal)is typically from 1 to 3.5, preferably from 1.6 to 3, more preferably from 2 to 2.8. Preferably, the alkali metal silicate is hydrous, having from 15% to 25% water, more preferably, from 17% to 20%.
The highly alkali metasilicates can in general be employed, although the less alkaline hydrous alkali metal silicates having a SiO₂:M₂0 ratio of from 2.0 to 2.4 are, as noted, greatly preferred. Anhydrous forms of the alkali metal silicates with a SiO₂:M₂0 ratio of 2.0 or more are also less preferred because they tend to be significantly less soluble than the hydrous alkali metal silicates having the same ratio.
Sodium and potassium, and especially sodium, silicates are preferred.
Enzymes may be present in the compositions of the invention. Examples of enzymes suitable for use in the cleaning compositions of this invention include lipases/peptidases, amylases (amylolytic enzymes) and others which degrade, alter or facilitate the degradation or alteration of biochemical soils and stains encountered in cleansing situations so as to remove more easily the soil or stain from the object being washed, or to make the soil or stain more removable in a subsequent cleansing step. Both degradation and alteration can improve soil removal.
Well-known and preferred examples of these enzymes are lipases, amylases and proteases. The enzymes most commonly used in machine dishwashing compositions are amylolytic enzymes. Preferably, the composition of the invention also contains a proteolytic enzyme. Enzymes may be present in a weight percentage amount of from 0.2% to 5% by weight. For amylolytic enzymes, the final composition will have amylolytic activity of from 10² to 10⁶ Maltose units/kg. For proteolytic enzymes the final composition will have proteolytic enzyme activity of from 10⁶ to 10⁹ Glycine Units/kg.
Bleach material may optionally and preferably be incorporated in composition for use in processes according to the present invention. These materials may be incorporated in solid form or in the form of encapsulates, and less preferably in dissolved form.
In general the level of bleach material is preferably greater than 0.5 wt% of a bleaching material. The bleach material may be a chlorine or bromine releasing agent, or a peroxygen compound. Peroxygen based bleach materials are however preferred.
Organic peroxy acids or the precursors therefor are typically utilized as the bleach material. The peroxyacids usable in the present invention are solid and, preferably, substantially water-insoluble compounds. By "substantially water-insoluble" is meant herein a water-solubility of less than about 1% by weight at ambient temperature. In general, peroxyacids containing at least about 7 carbon atoms are sufficiently insoluble in water for use herein.
Inorganic peroxygen-generating compounds are also is typically used as the bleaching material of the present invention. Examples of these materials are salts of monopersulphate, perborate monohydrate, perborate tetrahydrate, and percarbonate.
Monoperoxy acids useful herein include alkyl peroxy acids and aryl peroxyacids such as peroxybenzoic acid, and ring-substituted peroxybenzoic acids (e.g. peroxy-alpha-naphthoic acid); aliphatic and substituted aliphatic monoperoxy acids (e.g. peroxylauric acid and peroxystearic acid); and phthaloyl amido peroxy caproic acid (PAP).
Typical diperoxy acids useful herein include alkyl diperoxy acids and aryldiperoxy acids, such as 1,12-diperoxy-dodecanedioic acid (DPDA); 1,9-diperoxyazelaic acid, diperoxybrassylic acid, diperoxysebacic acid and diperoxy-isophthalic acid; and 2-decyldiperoxybutane-1, 4-dioic acid. Peroxyacid bleach precursors are well known in the art. As non-limiting examples can be named N,N,N',N'-tetraacetyl ethylene diamine (TAED), sodium nonanoyloxybenzene sulphonate (SNOBS), sodium benzoyloxybenzene sulphonate (SBOBS) and the cationic peroxyacid precursor (SPCC) as described in US-A-4,751,015.
If desirably a bleach catalyst, such as the manganese complex, e.g. Mn-Me TACN, as described in EP-A-0458397, or the sulphonimines of US-A-5,041,232 and US-A-5,047,163, is to be incorporated, this may be presented in the form of a second encapsulate separately from the bleach capsule or granule. Cobalt catalysts can also be used.
Among suitable reactive chlorine- or bromine-oxidizing materials are heterocyclic N-bromo and N-chloro imides such as trichloroisocyanuric, tribromoisocyanuric, dibromoisocyanuric and dichloroisocyanuric acids, and salts thereof with water-solubilizing cations such as potassium and sodium. Hydantoin compounds such as 1,3-dichloro-5,5-dimethyl-hydantoin are also quite suitable.
Particulate, water-soluble anhydrous inorganic salts are likewise suitable for use herein such as lithium, sodium or calcium hypochlorite and hypobromite. Chlorinated trisodium phosphate and chloroisocyanurates are also suitable bleaching materials.
Encapsulation techniques are known for both peroxygen and chlorine bleaches, e.g. as described in US-A-4,126,573, US-A-4,327,151, US-A-3,983,254, US-A-4,279,764, US-A-3,036,013, EP-A-0,436,971 and EP-A-0,510,761. However, encapsulation techniques are particularly useful when using halogen based bleaching systems.
If the tablet has more than one phase it is highly desirable if the bleach and the bleach catalyst is in a separate phase to the colouring agent.
A surfactant system comprising a surfactant selected from nonionic, anionic, cationic, ampholytic and zwitterionic surfactants and mixtures thereof is preferably present in the composition.
Typically the surfactant is a low- to non-foaming nonionic surfactant, which includes any alkoxylated nonionic surfactant wherein the alkoxy moiety is selected from ethylene oxide, propylene oxide and mixtures thereof, and is preferably used to improve the detergency without excessive foaming. However, an excessive proportion of nonionic surfactant should be avoided. Normally, an amount of 15% by weight or lower, preferably 10% by weight or lower, more preferably 7% by weight or lower, and preferably 0.1% by weight or higher, more preferably 0.5% by weight or higher, most preferably 1% by weight or higher is used.
Examples of suitable nonionic surfactants for use in the invention are the low- to non-foaming ethoxylated straight-chain alcohols of the Plurafac® RA series, supplied by the Eurane Company; of the Lutensol® LF series, supplied by the BASF Company and of the Triton® DF series, supplied by the Rohm & Haas Company.
Other surfactants such as anionic surfactant may be used, but may require the additional presence of anti-foam to surpress foaming. If an anionic surfactant is used, it is advantageously present at levels of 2 wt% or below.
A water-soluble polymeric polycarboxylic compound is also advantageously present in the dish wash composition. Preferably these compounds are homo- or co-polymers of polycarboxylic compounds, especially co-polymeric compounds in which the acid monomer comprises two or more carboxyl groups separated by not more than two carbon atoms. Salts of these materials can also be used.
Particularly preferred polymeric polycarboxylates are co-polymers derived from monomers of acrylic acid and maleic acid. The average molecular weight of these polymers in the acid form preferably ranges from 4,000 to 70,000.
Another type of polymeric polycarboxylic compounds suitable for use in the composition of the invention are homopolymeric polycarboxylic acid compounds with acrylic acid as the monomeric unit. The average weight of such homopolymers in the acid form preferably ranges from 1,000 to 100,000 particularly from 3,000 to 10,000.
Acrylic sulphonated polymers as described in EP 851 022 (Unilever) are also suitable.
Preferably, this polymeric material is present at a level of at least 0.1%, more preferably at levels from 1 wt% to 7 wt% of the total composition.
A chelating agent may be present in the composition. If present, it is preferable if the level of chelating agent is from 0.5% to 3wt% of the total composition.
Preferred chelating agents include organic phosphonates, amino carboxylates, polyfunctionally-substituted compounds, and mixtures thereof.
Particularly preferred chelating agents are organic phosphonates such as α-hydroxy-2 phenyl ethyl diphosphonate, ethylene diphosphonate, hydroxy 1,1-hexylidene, vinylidene 1,1 diphosphonate, 1,2 dihydroxyethane 1,1 diphosphonate and hydroxy--ethylene 1,1 diphosphonate. Most preferred is hydroxy-ethylene 1,1 diphosphonate (EHDP).
Anti-tarnishing agents such as benzotriazole and those described in EP 723 577 (Unilever) may also be included.
Optional ingredients are, for example, buffering agents, reducing agents, e.g., borates, alkali metal hydroxide and the well-known enzyme stabilisers such as the polyalcohols, e.g. glycerol and borax; anti-scaling agents; crystal-growth inhibitors, threshold agents; thickening agents and perfumes and the like.
Reducing agents may e.g. be used to prevent the appearance of an enzyme-deactivating concentration of oxidant bleach compound. Suitable agents include reducing sulphur-oxy acids and salts thereof. Most preferred for reasons of availability, low cost, and high performance are the alkali metal and ammonium salts of sulphuroxy acids including ammonium sulphite ((NH₄)₂ SO₃), sodium sulphite (Na₂SO₃) sodium bisulphite (NaHSO₃), sodium metabisulphite (Na₂S₂O₃) potassium metabisulphite (K₂S₂O₅), lithium hydrosulphite (Li₂S₂O₄), etc, with sodium sulphite being particularly preferred. Another useful reducing agent, though not particularly preferred for reasons of cost, is ascorbic acid. The amount of reducing agents to be used may vary from case to case depending on the type of bleach and the form it is in, but normally a range of about 0.01% to about 1.0% by weight, preferably from about 0.02% to about 0.5% by weight, will be sufficient.
It is preferable the pH of the wash liquor at ambient temperature is higher than 6.5, more preferably 7.5 or higher, most preferably 8.5 or higher. Preferably the pH is lower than 12, more preferably lower than 11.
The invention will now be illustrated by the following non-limiting Examples.

Example 1 - A three layer for machine dishwashing.

A particulate composition for matte surfaced regions was prepared by mixing the following ingredients

A uncoloured (white) particulate composition was prepared by mixing the following ingredients:

	Wt%
Sodium tripoly-phosphate (partially hydrated)	56
Na-disilicate	9
Nonionic detergent	6
Na-perborate	16
TAED	3
Manganese catalyst	1.1
Sodium polyacrylate	3.7
Enzymes	4.5
Minors	To 100

A particulate composition for making glossy-sufaced coloured regions was made by mixing the following ingredients:

	Example 1	Example A
	Wt%	Wt%
Polyethylene glycol 4000	47.5	47.5
Sodium tripoly-phosphate (partially hydrated)	47.5	0
Sodium citrate hydrate	0	47.5
Heavy metal sequestrant	2.5	2.5
Green dye solution (4% dye)	2.5	2.5

Example A provides a comparative example.

Three layer tablets were made by:
i) introducing 9g of the first composition into a mould of a tabletting press, compacting the composition and opening the mould;
ii) putting 4g of the second composition into the mould on top of the compacted first composition, compacting the contents of the mould and then opening the mould again;
iii) putting a further 9 g of the first composition into the mould, on top of the compacted second composition, then compacting the entire contents of the mould with more force than in the previous two steps, next opening the mould and ejecting the tablet from the mould.
The tablet had identical top and bottom layer of the first composition. Sandwiched between them was a thin middle layer of the second coloured composition.
On storage at ambient temperature for one month the coloured layer in Example A faded, the coloured layer in Example 1 did not.
The tablets handled well on storage and performed well in the wash.

Claims

A detergent tablet comprising:

a) a solid hydrocarbon poly ether,

b) a colouring agent and;

c) a hydratable acid or salt thereof.
A detergent tablet according to claim 1 in which the solid hydrocarbon poly ether is an alkoxylated alkylether.
A detergent tablet according to claim 1 or claim 2 in which the hydrocarbon poly ether is a polyethylene glycol.
A detergent tablet according to any preceding claim in which the polyethylene glycol has a molecular weight from 3000 to 8000.
A detergent tablet according to any preceding claim wherein the hydratable acid or salt is in an anhydrous or partially hydrated form.
A detergent tablet according to any preceding claim wherein the hydratable salt is an alkali metal carbonate, a bicarbonate, a phosphate or polyphosphate or citrate or a sulphate.
A detergent tablet according to any preceding claim comprising a water soluble phosphate.
A detergent tablet according to claim 7 wherein the water soluble phosphate is an alkali metal tripolyphosphate, sodium, potassium or ammonium pyrophosphate, sodium or potassium orthophosphate, sodium polymeta/phosphate in which the degree of polymerisation ranges from 6 to 21, or a salt of phytic acid.
A detergent tablet according to any preceding claim in which the hydratable acid or salt thereof is sodium tripolyphosphate.
A detergent tablet according to any preceding claim having two or more phases.
A detergent tablet according to claim 10, wherein at least 60% of the hydrocarbon ether is in a single phase.
A detergent tablet according to claim 11, wherein at least 90% of the hydrocarbon ether is in a single phase.
A detergent tablet according to any of claims 10 to 12 having three phases in which the phases are in the form of layers.
A detergent tablet according to claim 13, in which the centre layer of the tablet contains the solid hydrocarbon polyether, the colouring agent and the hydratable acid or salt thereof.
A tablet according to any preceding claim having a tablet strength from 50 to 300 newtons (N).
A tablet according to any preceding claim having a mass greater than 8g.
A tablet according to any preceding claim comprising from 0.1 to 5 wt% of a surfactant.
Use of a tablet according to any preceding claim for cleaning utensils within a machine dishwasher.