GB1580047A

GB1580047A - Process for preparing detergent compositions

Info

Publication number: GB1580047A
Application number: GB16641/76A
Authority: GB
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1976-04-23
Filing date: 1976-04-23
Publication date: 1980-11-26
Also published as: FR2348965A1; DE2717281A1; AT362482B; NL7704396A; ATA288177A; SE7704690L

Description

(54j PROCESS FOR PREPARING DETERGENT COMPOSITIONS (71) We, UNILEVER LIMITED, a company organised under the laws of Great Britain, of Unilever House, Blackfriars, London E.C.4, England, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a process for making detergent compositions.

Detergent compositions containing nonionic surfactants have been gaining in acceptance over the last few years so that they now generate a great deal of interest and activity. A study of the patent literature and knowledge of the practical situation demonstrates that detergent powders containing nonionic surfactants are extremely difficult to process. The problem occurs largely at the spray-drying stage and is a result of two phenomena. The first is autoxidation and the second volatilisation. Both of these produce undesirable emissions at the top of the spray-drying tower. Autoxidation also constitutes a fire hazard.

We have discovered that so-called "tower-emissions" can be considerably reduced by choosing an ethoxylated alcohol nonionic surfactant which contains at least 15 % by weight of alcohols having 16 or more carbon atoms ethoxylated to a level of from 7 to 20 moles of ethylene oxide per mole of alcohol.

Such a nonionic surfactant is not an especially good detergent in the fabric-washing situation, so in accordance with our invention we combine it with a detergency extender in the form of an alcohol having from 9-15 carbon atoms ethoxylated with an average of from 2-5 moles of ethylene oxide per mole.

Accordingly the present invention provides a process for preparing a powdered detergent composition comprising: (a) spray-drying a slurry comprising nonionic surfactant in the form of an alcohol contain ing at least 15 by weight of alcohols having 16 or more carbon atoms ethoxylated to an average level of from 7 to 20 moles of ethylene oxide per mole, and conventional detergent slurry components to form a spray-dried base powder, and (b) adding a detergency extender to the base powder in the form of an alcohol having 9-15 carbon atoms ethoxylated to an average level of from 2-5 moles of ethylen oxide per mole, the nonionic surfactant comprising from 20-80% by weight of the total weight content of nonionic surfactant and detergency extender.

Step (b) of the process of the invention can be carried out in any way desired but preferred ways are to spray the extender directly onto the base powder, either along or in admixture with other materials such as absorbents or to form an adjunct such as a noodle or granule also with an absorbent.

When the extender is sprayed directly onto the base powder it is preferred that the base powder should not contain soap, since this tends to reduce the absorbency.

The alcohol ethoxylates specified for use in this invention are prepared by condensation of ethylene oxide with a synthetic alcohol prepared either by the 'Oxo' process or by the Ziegler process, both of which are well known to those skilled in the art. Alternatively they may be produced by a condensation reaction involving a natural alcohol.

Ethoxylates referred to above as nonionic surfactants can be derived from primary alcohol material made by the Oxo process and containing about 20%of alpha branched material sold by Shell Chemicals Ltd as Dobanol 56 (registered trade mark) or sold by Shell Chemicals Inc as Neodol 56 (registered trade mark) by ethoxylation with from 7 to 20 moles per mole of ethylene oxide. Other ethoxylates falling into the class can be derived in the same way from tallow alcohol and also from synthetic analogues.

Ethoxylates referred to above as detergency extenders can also be derived from Dobanol or Neodol alcohols or from other alcohols, although in this instance the Cs-Cl l, Cl215 or C14-15 fractions which are sold as Dobanol or Neodol 91, 25 or 45 respectively will need to be used.

The amount of the ethoxylated alcohol mixture in the powdered detergent composition of the invention will be from 5 to 20 % by eight in total, preferably 5 to 18 % and most preferably 7 to 15%. Of this total, the nonionic surfactants will constitute from 20-80%, preferably 20-55% by weight.

As stated earlier, the detergency extenders 2 are difficult to incorporate into a powdered detergent composition by a spray-drying route, but they can be incorporated into a powdered detergent composition either by a spray-on route or by forming an adjunct. In either case, sprayed powder or the adjunct can be admixed with powdered detergent.

A number of spray-on routes have been disclosed in the patent literature for example in United States patent specification No's 3,838,072 and 3,886,098. In general terms a crutches slurry containing conventional heat-stable ingredients and, in the present invention a nonionic surfactant is spray dried in a counter-current spray-drying tower to form a spray dried powder. The remainder of the process can be operated in a number of modes. In a first mode the spray-dried powder together with an absorbent is fed to a rotating drum and is sprayed with, in this invention, a detergency extender. Alternatively in another mode the absorbent is fed to the drum alone and is sprayed. The resulting dry-mix is then combined with the spray-dried powder. In any mode it may be necessary to post-dose heat-sensitive ingredients to form a complete detergent powder.

The absorbent referred to can be sodium perborate monohydrate, sodium perborate tetrahydrate, silica soda ash or a mixture thereof or any other material which is found to be suitable.

The detergency extenders may be sprayed onto the spray-dried powder and/or absorbent as liquids in neat form, if necessary using heat to convert them to mobile liquids. Alternatively they can be dissolved in water and sprayed as a solution.

We have found that it can be advantageous if an aqueous solution of the nonionic surfactants if gelled. The gel can then be warmed to render it mobile during spraying, and on cooling the gel will reform. so minimizing any tendency of the nonionic surfactant to bleed from the portion of the composition which has been sprayed rather than spray-dried. Gelling can be achieved for example by the addition of finely-divided silica or a cellulose derivative to the solution. Other materials which can be used are citric acid, copolymers of ethylene and maleic anhydride and sodium silicate.

The spray-on route to compositions of the invention will be further illustrated in the examples.

As an alternative to spraying the detergency extender onto the spray dried powder, it can be formed into an adjunct such as a granule or noodle and admixed with spray-dried powder.

The technology of adjunct formation is well known to those skilled in the art. Granules can be formed in apparatus such as Eirich (Registered Trade Mark) inclined pan granulators in which a particulate material is supplied to the top of an inclined rotating pan and sprayed with a solution which assists in the formation of granules, which are removed from the bottom of the pan. In granulation for the detergents industry the particulate material can be practically any of the materials which are commonly incorporated into detergent compositions, such as builders, oxygen bleaches. fillers such as sodium sulphate or minor ingredients such as enzymes or anti-redeposition agents. In the application of granulation to this invention the granulating solution would be an aqueous solution of a detergency extender.

The technology of noodling is also well known to those skilled in the art. The process of noodling generally involves supplying a plastic substance, for example a mixture of one of the common detergent ingredients listed above with a detergency extender to a hopper, plodding the substance to further plasticize it and extruding it through a die to form noodles.

Conventional ingredients in conventional amounts can be incorporated into the slurry which is spray-dried in accordance with the invention.

Thus soap can be incorporated to help to reduce the bulk density of the powder. The term "soaps" is intended to include alkali metal salts such as the sodium and potassium salts as well as ammonium and alkanolaminium salts of fatty acids containing from about 8 to about 26 carbon atoms, preferably 10 to 22 carbon atoms. The most usual soaps for industrial use are the sodium and potassium salts of tallow and coconut fatty acids and mixtures thereof, and these and hardened rape-seed oil soaps are preferred in this invention. Soap may be present in an amount of up to about 3% by weight of the spray-dried powder.

In addition the slurry can and normally will contain detergency builders in an amount up to about 75% by weight of the spray-dried powder, preferably 10-60% and most preferably 30-60%. Any of the builders which have been suggested in the art may be used, for example the water soluble ortho-, pyro- and tripolyphosphates, carbonates, bicarbonates and silicates, especially the sodium salts. The combination of sodium tripolyphosphate with alkaline sodium silicate, that is sodium silicate having an Na2O: SiO2 ratio in the range 1:1.6 to 1:2.0 has been found especially useful, although combinations with silicates having different Na2O: SiO2 ratios are not excluded.

The builders which have been suggested in response to pressure to reduce the phosphorus content of detergents are also suitable for use with the process of this invention. For example the salts, especially sodium salts of ethylene diamine tetraacetic acid, nitrilotriacetic acid, oxydisuccinic acid, citric acid, oxydiacetic acid, alkenyl succinic acid, polyacrylic acid, hydrofuran tetracarboxylic acid, alkylaryl succinic and malonic acids, dipicolinic acid, alkane disulphonic acid, sulphosuccinic acid, and alkyl phthalic acid are all suitable. Other builder materials which can be used include oxidised polysaccharides, especially oxidised starch, carboxymethyloxysuccinates and their hydrates and analogues, sulphonated fatty acid salts, "seed" builders such as the carbonate/calcite combination, and aluminosilicates.

Other components of detergent compositions can be added to the slurry or post-dosed into the spray-dried base powder according to their known suitability for undergoing a spraydrying process.

Examples of such components are oxidising bleaches such as sodium perborate and percarbonate optionally with bleach precursors such as tetra acetyl ethylene diamine, and tetra acetyl glycoluril, suds suppressors such as silicone oils, alkyl phosphates and microcrystalline waxes, soil suspending agents such as sodium carboxymethyl cellulose ethers, and copolymers of maleic anhydride with ethylene or methyl vinyl ether, enzymes such as those sold under the trade names "Alcalase", (Registered Trade Mark). "Esterase" and "SP72" by Novo Industries A/S, Denmark, fluorescers and soil release agents such as cellulose ethers and copolymers of polyoxyethylene glycol and polyethylene terephthalate.

These conventional and optional components of the detergent compositions can be present together in an amount of from 15 to 50% by weight of the finished composition when an oxidising bleach is present or at substantially lower levels in the absence of such bleach.

The invention will be more readily understood by reference to Figures 1 and 2 of the accompanying drawings in which Figure 1 shows an apparatus for operating one mode of the process and Figure 2 shows an apparatus for operating another mode of the process in which base powder is mixed with sprayed absorbent substance after the spraying step.

Referring to figure 1, a conventional spray drying tower (10) produces spray dried base powder from an aqueous slurry of detergent ingredients. The slurry will usually contain all the heat stable ingredients, for example the nonionic surfactant detergency builder and antiredeposition agent. The base powder falls onto a conveyor (11) and is fed via an air lift (12) to a base powder silo (13). From the silo the base powder falls to a conveyor (14) and down a slide (15) into a rotating drum (16). A second slide (17) brings powdered absorbent material into the rotating drum from storage silo (18) via conveyor (19). The absorbent and the base powder are tumbled in the rotating drum together. Whilst being tumbled they are sprayed from nozzles (20) with the detergency extender in liquid form or in aqueous solution. This material is fed from a storage tank (21) through a metering pump (22).

The rotating drum (16) is provided with a weir (23) over which a homogenous mixture of sprayed base powder and or absorbent passes. This spray-mixed powder is then dosed with heat sensitive ingredients from silos (24) (25) and (26), the ingredients being fed to the drum (16) by means of conveyors (27), (28), (29) and (30) and funnel (32). The resulting finished detergent powder is then fed to packaging machines through a shute (31).

Referring now to figure 2, the spray dried phase powder is fed to the rotating drum (16) in the same way as described in relation to figure 1. Similarly the dry dosed ingredients in silos (24), (25) and (26) are fed to the rotating drum (16) in the same way. The description of these parts of figure 2 which also appear in figure 1 will not be repeated.

In the process illustrated in figure 2, powdered absorbent in a silo (33) is allowed to fall onto a conveyor (34) from where it is conveyed to a rotating drum (35) by a slide (36). Here it is sprayed with liquid nonionic surfactant or aqueous nonionic surfactant solution as in the process illustrated in figure 1 supplied by a metering pump (22) as shown in figure 1, from nozzles (37). The sprayed absorbent then passes from the drum (35) through a funnel (38 into a silo (39). It is then fed into the rotating drum (16) via a conveyor (40) and a slide (41 when required.

The process of the invention will now be further described in the following specific examples, Example 1 Two spray-dried base powders were prepared by spray-drying a slurry of detergent powder ingredients having a moisture content of 48%. The slurry temperature used was 70-80"C and the spray-drying was carried out at atmospheric pressure using an inlet air temperature of about 310"C and an outlet of no greater than 105"C. The resultant base powders A and B had bulk densities of 0.258 and 0.274 respectively and formulations as follows:: % by weight of finished powder A B Nonionic surfactant 2.50 Sodium tripolyphosphate 28.20 28.20 Sodium soap of tallow fatty acid 2.00 2.00 Sodium silicate (1.6 1) 5.00 5.00 Coconut monoethanolamide 1.50 1.50 Minor ingredients 1.82 1.80 Moisture 7.88 7.90 Example 2 A spray-dried base powder prepared by the method described in Example 1 and having formulation A was combined with a dry-mixed adjunct prepared as follows: A charge of 16.25 Kg containing 74.4% by weight of sodium perborate monohydrate and 25.6% buy weight of puffed borax was placed in a 50 litre Lodige mixer. 4.1Kg of a detergency extender 2 was sprayed on to the charge at a pressure of 5 atmospheres.

The resultant combination was then dosed with heat sensitive ingredients to produce a finished powder having the following formulation: % by weight of finished powder Spray-dried base Powder Nonionic surfactant 2.50 Sodium tripolyphosphate 28.20 Sodium soap of tallow fatty acid 2.00 Sodium silicate (1.6 1) 5.00 Coconut monoethanolamide 1.50 Minor ingredients and moisture 9.70 Dry-mixed adjunct Detergency extender 8.20 Puffed borax 8.00 Silica 1.00 Sodium perborate monohydrate 24.50 Dry Dosed Ingredients Enzyme speckles 5.20 Blue sodium tripolyphosphate speckles 2.00 Palm kernel monoethanola mide 2.20 Perfume q.s.

Total 100.00 Example 3 35.25Kg of a charge was placed in a 30 litre Lodige mixer. The charge contained 53.9%by weight of a spray-dried base powder prepared by the method described in Example 1 and having formulation A, 34.8% by weight of sodium perborate monohydrate and 11.3% by weight of puffed borax. This charge was then sprayed at 500C with a gel consisting of 8.20% by weight of the finished powder of a detergency extender, 1.30% of finely-divided silica, 1.00 of sodium carboxymethyl cellulose and 2.30% by weight of water.Other heat sensitive ingredients were then dry-dosed into the resultant powder so that a finished powder having the following formulation was obtained: So by weight of finished powder Spray-mixed powder Nonionic surfactant 2.50 Detergency extender 8.20 Sodium tripolyphosphate 28.20 Sodium soap of tallow fatty acid 2.00 Sodium silicate (1.6:1) 5.00 Coconut monoethanolamide 1.50 Puffed borax 8.00 Sodium carboxymethyl cellulose 1.50 Finely divided silica 1.30 Sodium perborate monohydrate 24.50 Moisture 6.30 Minor ingredients 1.82 Dry-dosed Ingredients Enzyme speckles 5.20 Blue sodium tripolyphosphate speckles 2.00 Palm kernel monoethanolamide 2.20 Perfume, minor ingredients and moisture to 100.00 Example 4 The following three base powders were prepared:: % by weight of finished powder A B C Dobanol 56 E 10*, nonionic surfactant - 6.0 12.0 Dobanol 25 E 3 ,a detergency extender - 6.0

Dobanol25 E 7 Sodium tripolyphosphate 36.0 Alkaline sodium silicate 7.0 Minor ingredients 2.5 Moisture 12.0 *The expression "E 10" and similar expressions used herein means that the molecules are ethoxylated to an average of 10 moles of ethylene oxide per mole of alcohol.

Powders A and C were prepared by a conventional spray-drying process using an air inlet temperature of 3000C with aeration of the crutcher slurry.

Powder B was made by spray-drying a slurry containing all of the specified components other than the Dobanol 25 E3. This latter component was sprayed onto the spray-dried base powder using a pressure of 5 atmospheres. The bulk density of the resultant powders was 0.31, 0.38 and 0.28 g/ce respectively.

The gases emerging from the top of the spray-drying tower were analysed for nonionic surfactant content with the following resutls.

mg of nonionic surfactantlm3 300"C 350"C Powder A (17.25ÓDobanol25-E 7) 100 150 Powder B ( 9.4% Dobanol 56-E10) 20 35 Powder C (17.2% Dobanol 56-E10) 30 70 This demonstrates quite conclusively that using the process composition of this invention does reduce the effluent from the spray-drying tower.

Example 5 Three detergent compositions having the following formulation were made by admixture: Parts by weight A B C Dobanol 25 E71 12.0 Dobanol 56 E102 6.00 12.0

Dobanol 25 E33 Sodium tripolyphosphate 36.00 Sodium toluene sulphonate 1.25 Alkaline silicate 7.00 Sodium carboxymethyl cellulose 0.50 Gantrez AN 119 0.40 EDTA 0.10 Fluorescer 0.20 57.45 Test cloths of crimped polyester soiled with a standard soil of synethetic sebum and carbon black were washed in a Tergotometer (registered Trade Mark).Washing conditions were as follows: Product concentration 0.05-1.00% Water hardness 24 H Temperature 55"C Wash duration 10 minutes The reflectance of the washed cloth was then compard with that of an unwashed one using a Zeiss "Elrepho" (registered trade mark) photometer. The results are shown in the following table TABLE TABLE REFLECTANCE CHANGE (AR)

Product conc. % 0.05 0.10 0.20 0.40 0.60 1.00 Composition A 8.9 6.5 8.0 21.4 27.6 27.8 B ~ 5.6 3.8 7.8 19.3 24.5 31.1 C C 4.3 4.5 3.8 7.6 11.5 23.5 It can be seen that by incorporating a detergency extender in accordance with the invention into a nonionic surfactant. in accordance with the invention (composition B). it is possible to achieve detergency substantially equivalent to that obtainable from a conventional nonionic surfactant (composition A).

1,3 Dobanol 25 E7 and Dobanol 25 E3 (registered trade mark) are C12-15 primary Oxo alcohols ethoxylated with an average of 7 and 3 moles of ethylene oxide/mole, respectively.

2 Dobanol 56 E10 (registered trade mark) is a C15/C16 primary Oxo alcohol ethoxylated with an average of 10 moles of ethylene oxide per mole.

WHAT WE CLAIM IS: 1. A process for preparing a powdered detergent composition comprising (a) spray drying a slurry comprising a nonionic surfactant in the form of an alcohol containing at least 15% by weight of alcohols having 16 or more carbon atoms ethoxylated to an average level of from 7 to 20 moles of ethylene oxide per mole, and conventional detergent slurry components to form a spray-dried base powder, and (b) adding a detergency extender to the base powder in the form of an alcohol having 9-15 carbon atoms ethoxylated to an average level of from 2-5 moles of ethylene oxide per mole, the nonionic surfanctant comprising from 20-80% by weight of the total weight content of nonionic surfactant and detergency extender.

2. A process according to claim 1, wherein the detergency extender is sprayed onto the spray-dried base powder.

3. A process according to claim 2, wherein the detergency extender is sprayed onto an absorbent.

4. A process according to any one of claims 1, 2 or 3, wherein the detergency extender is formed into an adjunct.

5. A process according to claim 4, wherein the adjunct is a granule or a noodle.

6. A process according to claim 3, wherein the absorbent comprises sodium perborate monohydrate, sodium perborate tetrahydrate, silica, soda ash or a mixture thereof.

7. A process according to either of claims 2 and 3, wherein an aqueous gel of the detergency extender is formed.

8. A process according to any one of preceding claims 1 to 7. characterised in that the slurry comprising the nonionic surfactant also comprises up to 3 % based on the weight of the spray-dried powder, of a C8-C26 soap.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.