GB2445938A

GB2445938A - Detergent granule

Info

Publication number: GB2445938A
Application number: GB0701560A
Authority: GB
Inventors: William John Wilson
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 2007-01-27
Filing date: 2007-01-27
Publication date: 2008-07-30
Also published as: GB0701560D0

Abstract

A detergent granule comprises: <SL> <LI>(i) a LAS/Nonionic surfactant blend at LAS:nonionic ratios of 11:1 to 2:1, preferably 4:1 where the total wt% of LAS and nonionic in the granule is from 40 to 55 wt%, <LI>(ii) a high surface area carrier at a level of from 10 to 40 wt% of the granule, and <LI>(iii) a particulate inorganic alkaline material at a level of from 5 to 30 wt% of the granule. </SL> Preferable the carrier is zeolite A ad the alkaline material sodium carbonate. Also disclosed is a process for manufacturing the granule by: <SL> <LI>a) mixing LAS acid and non-ionic to form a pre-blen; <LI>b) dosing the pre-blend formed in step (a) to a VRV reactor containing a source of particulate inorganic alkaline material and particulate carrier material. </SL>

Description

Granulation of LAS nonionic blends using a VRV

Technical field

This invention relates to the dry neutralisation of LAS acid in the presence of nonionic surfactant in a VRV flash reactor.

Background

It is known to use a horizontal Flash Drier system such as a VRV flash dryer, from VRV SpA Implant! Industriali, as a flash reactor for the dry neutralisation and granulation of anionic surfactant. The drying zone of the VRV reactor may have a heat transfer area of at least 10 m2. The cooling zone of the reactor desirably has a heat transfer area of at least 5 m2.

Use of calcium tolerant surfactant, or calcium tolerant blends of surfactants, is of interest to detergent formulators because it allows use of lower levels of builder. This frees up formulation space and saves chemical usage. One such calcium tolerant blend is a mixture of LAS with nonionic surfactant, especially a nonionic surfactant having a relatively high degree of ethoxylation; for instance and average of 30E0.

It is desirable to make a high active granule containing at least 4Owt% of the calcium tolerant blend. The optimum ratio of LAS to Nonionic 30E0 has been found to be about 4 to 1. Ideally, the manufacturing process should take place in a high throughput equipment like a VRV flash reactor/drier (VRV).

It has been proposed to use such High active granules as a major part of a detergent product, without the need for high levels of builders. This should give cost, energy and environmental savings.

High act ve granules consisting of single anionic surfactants (LAS, PAS, soap) have previously been made using a VRV.

There have been proposals to combine such anionic granules with nonionic granules made on different equipment. The VRV has been thought to be unsuitable for processing of high active nonionic granules.

In W02005/054422, a VRV flash dryer is used together with exemplified LAS acid neutralisation. It is stated that the anionic surfactant can be any of the known anionic surfactants. However, there is a preference for the salts of LAS and PAS surfactants: LAS being long chain alkyl benzene suiphonates and PAS being primary alkyl suiphates.

The claims cover a process where all of the necessary ingredients for a composition may be introduced into the VRV. In particular, this publication discloses a powdered detergent composition obtained by a thin layer drying process, the composition comprising inter alia: anionic surfactant and optionally fatty acid soap together with a support material and a sequestrant and/or anti oxidant. The preferred anionic surfactants are LAS and/or PAS. The composition may also comprise up to 20 wt % of other surfactants, in particular up to 20 wt% of nonionic and/or cationic surfactants. The composition may be made by a process wherein the ingredients of the detergent composition, comprising at least part of the total amount present in the whole composition of at least one of the ingredients selected from the group consisting of support material, anti-oxidant and sequestrant are introduced in a mixer at a first point of introduction and homogenised at a temperature between 10 and 160 C while the remainder of anti-oxidant and/or sequestrant and/or support material is introduced in the mixer at a second point of introduction downstream from the first point of introduction, while the mixture obtained can be sprayed dried by spraying it on the support material. A VRV mixer is preferred. There are no examples where nonionic is introduced to the VRV.

Compositions comprising anionic and nonionic surfactants may also be made by spray drying. The total surfactant level in such compositions is typically about 20 to 30% and high levels of nonionic usually need to be post dosed, which requires an extra process step.

A single stage process to produce high active anionic nonionic granules is still sought.

Summary of the Invention

According to a first aspect of the invention there is provided a detergent granule comprising three components: (i) a LAS/Nonjonjc surfactant blend at LAS:NI ratios of 11/1 to 2/1 where the total weight% of LAS and nonionic in the granule is from 40 to 55 wt, (ii) a high surface area carrier at a level of from 10 to 40 wt% of the granule, and (iii) an inorganic electrolyte at a level of from 5 to wt% of the granule.

Preferably the LAS (linear alkylbenzene sulphonate) is a sodium salt of an alkylbenzene suiphonic acid having an alkyl chain length of 12 to 14.

The preferred nonionic surfactants have a melting point greater than 30 C and most preferred are C12-15 alcohols ethoxylated with an average of 30 ethylene oxide units.

The preferred carrier is Zeolite, particularly Zeolite A, but Zeolite MAP may alternatively be used.

The preferred inorganic electrolyte is sodium carbonate, particularly excess sodium carbonate of the same type as was used for the neutralisation of the LAS acid.

According to a second aspect of the invention there is provided a process to manufacture the granule according to the first aspect of the invention, the process comprising the steps of: (i) mixing the LAS acid and the nonionic to form a pre-blend, (ii) dosing the pre-blend formed in step Ci) to a VRV containing a source of particulate inorganic alkaline material and particulate carrier material(s) and optionally other solid particulate materials.

Advantageously the maximum process temperature is less than 100 C.

Lowering the jacket temperature and reducing the rotor speed relative to that used for 100% LAS surfactant facilitates an increase in the level of mixed active back to nearer to the maximum possible for the LAS granule.

Lowering the temperature of both jackets 1 and 2 is desirable as it enables higher AD granules to be produced; however, it is also advantageous if only the second jacket temperature is lowered.

It is advantageous to use lowered jacket temperatures and reduced rotor speed in order to increase the throughput of the process to make the LAS nonionic blend back to the levels normally encountered for LAS granules.

Pre-blending the nonionic into the LAS acid ensures perfect mixing. Because the presence of the nonionic speeds up the neutralisation reaction by lowering viscosity, it is possible and desirable to run the VRV at lower than usual temperatures e.g. less than 100 C.

This process enables the production of granules having high surfactant levels and reduces the need to formulate with otherwise unnecessary chemicals. The process also eliminates the need to blend the anionic and nonionic granules together after their manufacture, as is done in the adjunct process.

The invention will now be further described with reference to the following non limiting examples.

Examples

Examples 1 to 9

To investigate the effect of the ratio of anionic to nonionic and the type of nonionic on the maximum surfactant level that could be obtained in the granule a series of tests where carried out. The results are shown in Table 1.

Table 1

I Maximum AID possible (maintaining a good ______________ powder) for specified EO type Las/NI Ratio 7 EO 11EO 30E0 / 5 57.7 (E.g. 53.4 (E.g. 59.7 (E.g.

_______________ 1) 4) 7) / 10 48.0 (E.g. 49.5 (E.g. 55.3 (E.g.

_______________ 2) 5) 8) / 20 41.1 (E.g. 42.0 (E.g. 50.3 (E.g.

_______________ 3) 6) 9) If the AD becomes too high then the product turns into a paste which results in machine blockage. It can be seen that use of 30E0 nonionic gives the most consistent product with over 50% AD across a range of ratios.

Examples 10 to 14 -LAS ACID reaction rate Table 2 -Free Acid analysis E.g. Sample % Free ____ ____________________ Las Acid 100% Las 581 11 80:20 Las:NI 25.3 12 80:20 Las:NI + 50% 4A 11.4 13 80:20 Las:NI + 30% 4A 12.3 14 80:20 Las:NI + 10% 4A 15.2 A series of tests was performed to investigate the effect of use of nonionic and Zeolite inorganic carrier material on the rate of neutralisation of LAS acid by sodium carbonate I a VRV. It can be seen from table 2 that the addition of NI speeds up the neutralisation reaction rate, as evidenced by reduction of free LAS acid. Use of Zeolite further improves the conversion in the presence of nonionic.

Examples 15 to 18 Effect of process conditions Further tests were performed in order to determine how much nonionic could be dosed to the VRV before the granulation product had an unacceptably low level of total surfactant, due to the inability to granulate successfully at higher AD levels. The tests started with 100% LAS acid (i.e. no nonionic) and the feed liquid was changed in steps of 5% (w/w) mixtures of the LAS/NI (i.e. 95:5, 90:10 etc) . The formulations details and process conditions are shown in

tables 3 and 4.

Table 3 -Formulation Details _____ Ratio ____ % _____ ____ ____ _____ ____ E.g. NaLas 30E0 Total NaLas 30 Ash Suiph 4A Othe NI AD EO ate Zeoli rs _____ _____ ____ ______ ______ NI te _____ E.g. 100 0 63.00 63. 00 0.00 15.2 1.6 18.9 1.3

______ _____ _______

E.g. 95 5 63.30 60.14 3.17 15 1.6 18.8 1.3 16 ______ _____ E.g. 90 10 63.30 56.97 6.33 15 1.6 18.8 1.3 17 ______ _____ _______ _______ _____ E.g. 90 10 55.60 50.04 5.56 19.7 1.7 21.9 1.3 18 ______ Table 4 -Process Conditions

_________

_______ Temp C __________ rpm m3/Hr ____________ E.g. Jacket 1 Jacket Jacket 3 Rotor AIR Throughput 2 counter E.g. 150 150 5 3000 11.5 83Kg/Hr E.g. 150 150 5 3000 11.0 83Kg/Hr 16 _________ _______ __________ _______ _________ ____________ E.g. 150 150 5 3000 N1A 83Kg/Hr 17 _________ _______ E.g. 150 150 5 3000 12.6 83Kg/Hr 18 _________ _______ Examples 15 and 16 gave acceptable granules, as detailed in table 5. However, it was not possible to form a granule using the mix of E.g. 17: a large wet over granulated mass was produced. It is clear that when processing at the standard LAS conditions of 150 C the addition of between 5 and 10 % by weight of 30E0 NI to the system causes severe processing problems. E.g. 18 was successfully granulated at the 90:10 LAS: NI ratio but the active level had to be reduced to 55.6% to make this possible.

Table 5 -Powder Properties E.g. BD DFR %C UCT Free AD measured Moisture T90 Acid (Las component _____ ____ ____ ____ _____ only) ________ _____ E.g. 673 96 11.2 0 1.38 59 5.1 35 E.g. 713 65 8.8 0.4 0.41 52 (=55 6.1 29.2 16 _____ ____ _____ _____ total) _________ _____ Examples 19 to 21 further optimisation trials.

Further examples were done to investigate the effect on maximum active level of lowering the jacket temperature and varying rotor speed. In particular, it is shown that lowering the temperature of both jackets 1 and 2 enabled higher AD and was the same as lowering only the second jacket temperature.

It was possible to use lowered jacket temperatures and reduced rotor speed in combination to increase the throughput to a typical value for a LAS only process.

The aim of these examples was to find the optimum process conditions to make a granule with the highest AD, at the highest throughput possible.

The formulation and process parameters used for the trial can be found in tables 6 and 7 respectively.

-10 -Table 6 -Formulation Details ______ Ratio ____ % _____ _____ ____ _____ _____ _____ E.g. NaLas 30E0 Total NaLas 30 EQ Ash Suipha 4A Others NI AD NI te Zeolit _________ ________ ______ e 029-Eg 80 20 50.80 40.64 10.16 21.5 0.6 26 1.1 19 ______ 029-3 80 20 50.30 40.24 10.06 21.5 0.5 26.6 1.1 029-4 80 20 55.30 44.24 11.06 18.4 0.6 24.5 1.2 Table 7 -Process Conditions Temp C Rpm m3/Hr 100% = ______ ______ ______ _______ ______ _________...83Kg/Hr E.g. Jacket Jacket Jacket 3 Rotor AIR counter Throughput ____ 1 2 E.g. 94 94 5 2560 10.2 66% 19 _______ _______ ________ E.g. 94 94 5 2560 10.3 100%

_______ _______ ________ _______ __________ ______________

E.g. 94 94 5 2100 10 100% 21 _______ The key differences within the trial were the increase in throughput between examples 19 and 20, and an increase in active level at full throughput between examples 20 and 21.

Table 8 gives some of the properties of the granules and from table 9 it can be seen that there is a significant change in the particle size distribution of examples 20 and 21 (but only one example is given???). At the higher active level, the particle size has a slightly less even distribution, a result of higher levels of oversize being present. This effect appears to be caused by the reduction in rotor speed and is also a result of the higher active level. Rotor speed is an important process parameter with -11 -respect to particle size. It is possible to increase the active level but it is likely that the oversize will increase.

Table 8 -Granule Properties E.g. BD DFR %C UCT E.g. 19 672* __________ __________________ E.g. 20 713 118 11.2 0 E.g. 21 659 123 11.2 0 * E.g. 19 was tested after sieving to a cut of 1200 -250jLm.

Physical properties' testing was performed on the sieve cut. RH was 25.9%.

Table 9 Particle Size Distribution Sieve Eg19* Eg20 Eg21 <180 1.5 4.4 3.5 250-180 4.4 4.4 3.5 355-250 16.5 9.6 8.2 500-355 28.6 15.5 13.5 710-500 34.2 23.6 22.6 1000-710 14.9 21.0 20.3 1400-1000 ______ 14.4 14.7 >1400 7.0 13.5

Claims

-12 -Claims: 1. A detergent granule comprising: (1) a LAS/Nonionjc surf

actant blend at LAS: flofliOflic ratios of 11:1 to 2:1, preferably 4:1 where the total wt% of LAS and nonionic in the granule is from 40 to 55 wt%, (ii) a high surface area carrier at a level of from 10 to 40 wt% of the granule, and (iii) a particulate inorganic alkaline material at a level of from 5 to 30 wt% of the granule.
2. A granule as claimed in claim 1 wherein the LAS (linear alkylbenzene suiphonate) is a sodium salt of an alkylbenzene suiphonic acid having an alkyl chain length of 12 to 14.
3. A granule as claimed in claim 1 or claim 2 wherein the nonionic surfactant has a melting point greater than 30 C.
4. A granule as claimed in claim 3 wherein the nonionic surfactant is aCl2-15 alcohol ethoxylated with an average of 30 ethylene oxide units.
5. A granule as claimed in any preceding claim wherein the carrier is a Zeolite, preferably Zeolite A.
6. A granule as claimed in any preceding claim wherein the particulate inorganic alkaline material is sodium carbonate.

-13 -
7. A process to manufacture a granule as claimed in any one of claims 1 to 6, the process comprising the steps of: (1) mixing LAS acid and nonionic to form a pre-blend, (ii) dosing the pre-blend formed in step (i) to a VRV containing a source of particulate inorganic alkaline material and particulate carrier material(s) and optionally other solid particulate materials.
8. A process according to claim 7 wherein the maximum process temperature in the VRV is less than 100 C.
9. A process according to claim 8 wherein the rotor speed is less than 2500 rpm.