GB2523837A

GB2523837A - Surfactant mixing

Info

Publication number: GB2523837A
Application number: GB1404098.4A
Authority: GB
Inventors: Martin Crossley; Paul Emsley; Mark G Spence
Original assignee: OREAN PERSONAL CARE Ltd
Current assignee: OREAN PERSONAL CARE Ltd
Priority date: 2014-03-07
Filing date: 2014-03-07
Publication date: 2015-09-09
Anticipated expiration: 2034-03-07
Also published as: GB201404098D0; GB2523837B

Abstract

A batch method of diluting a foaming surfactant is carried out in a machine having a mixing vessel 2, an anchor mixer having an anchor paddle 10 in the base of the vessel and upper mixing blades 12 for promoting downward axial mixing with both driven by a first axial shaft 4, and a high shear mixing element 20 mounted in the vessel between the anchor paddle and upper mixing blades and driven by a second axial shaft 6 in the opposite direction to the first shaft wherein the vessel is charged with concentrated surfactant and water, and the anchor mixer started slowly and brought up to speed before the high shear mixing element is started so that the anchor mixer rotates in the opposite direction to the high shear mixer, and the temperature is maintained between 34-45Â°C. The arrangement of contra-rotating mixers suppresses/minimises foam creation.

Description

Surlactant Dilution Method

Technical Field

[0001] The present invention relates to the dilution of concentrated foaming surlactant for use in the cosmetics industry.

Background Art

[0002] When manufacturing a cosmetic formulation from a range of ingredients, a cosmetics manufacturer will typically use sophisticated in-line dilution systems to dilute concentrated surfactants for use. These in-line dilution systems are expensive, and, therefore limited to large scale manufacture.

[0003] There are technical problems in diluting a batch of concentrated surlactant as they suffer from production of excessive foam during mixing.

[0004] While foam suppressants are available, the presence of these chemicals in the diluted surfactant would be prejudicial to its subsequent use in a cosmetic product. This is particularly the case for suppressants containing hydrocarbons or phosphates.

Disclosure of Invention

[0005] The method of the present invention as defined in the claim solves the above technical problem.

Brief Description of Drawings

[0006] In order that the invention may be well understood some examples will be described by way of example only with reference to the accompanying diagrammatic drawing which shows an example of a mixer suitable for carrying out the method of the invention.

Mode(s) for Carrying Out the Invention [0007] A batch method of diluting concentrated surlactant, particularly sodium lauryl ether sulphate (SLES) is carried out in a machine as shown in the Figure. The machine has a mixing vessel 2 with a capacity of, for example, 2000 litres. The machine is equipped with two concentric contra-rotating drive shafts 4, 6 for separate impellers. Each shaft is driven by a respective drive motor. The mixer has controls which allow the motors to be started, accelerated and run for programmable periods. This type of mixer is commercially available and is used for mixing pastes, for example toothpaste.

[0008] The inner shaft 4 carries an anchor type impeller or mixer having a mixing blade or anchor paddle 10 in the base of the vessel 2. The paddle 10 is shaped to stir the mixture and lift the contents of the vessel away from the base. This anchor mixer also supports upper mixing blades 12 on the shaft 4. These blades are inclined for promoting downward axial movement in the contents of the vessel. The shaft 4 can be driven at speeds in the range 40-80 rpm.

[0009] The second outer shaft is connected to a high shear mixing element 20 mounted in the vessel between the base and upper mixing blades 12. This mixer can reach speeds in excess of 2500rpm. It moves in the opposite sense to the inner shaft and its impellers.

[0010] The rating of the motors depends on the size of the mixing vessel. Each motor needs a shaft power of 10 to 20kW per cubic meter capacity of the mixed product.

[0011] In order to carry out the batch method of the invention, using such a mixer, the vessel is first charged with an appropriate quantity of the 70% concentrated surfactant, (typically 35 to 40 vlv%), and demineralised water (65 to 60 v/v%)and the anchor mixer started slowly and brought up to speed over a period of several minutes, preferably at least 2 minutes and typically 5, before the high shear mixing element is started. The high shear mixer is then started and run for a period of 2-3 hours to complete the dilution. If the diluted surlactant is to be preserved, caustic soda solution is used as a preservative to a concentration in the batch in the range 0.01 -0.03 wlv%.

[0012] The contents of the mixing vessel are maintained at a temperature in the range 34-45 °C for the duration of the mixing.

[0013] While this arrangement of contra-rotating impellers was designed to prevent accumulations of dry ingredients being left in the base of the vessel, it has been unexpectedly found that establishing the axial motion, before and during the use of the high shear impeller, has the effect of suppressing the foam creation that would otherwise be expected if the mixture was subjected to high shear mixing alone.

[0014] Driving the shaft 4 at speeds of less than 40 rpm leads to increased foaming. Driving the shaft 4 at speeds in excess of 80 rpm leads to excessive torque in the drive shaft and a potential loss of liquid from the batch, as the surface of the solution becomes excessively concave.

[0015] This diluted SLES can then be incorporated into other batch mixed products such as shampoos and hand wash. In such products the diluted product will typically comprise 14%, 15% or up to 25% of the formulation.

Examples

[0016] A batch of N litres was made up of * 36 v/v% Concentrated SLES * 64 v/v% Demineralised water * 0.02 w/v% Caustic soda [0017] The anchor mixer was started and run up to a speed of 60 rpm over 5 minutes. Then the high shear mixer was run up to 2000rpm and the mixing continued for 2 hours. The vessel was maintained at 45 °C for the duration of the mixing.

Claims

Claims 1. A batch method of diluting a foaming surfactant in a vessel (2) of a machine having an anchor mixer (4,10,12) driven in a first sense and a high shear mixer (6, 20) driven in the opposite sense, the high shear mixer having a mixing element (20) positioned axially between an anchor paddle (10) in a base of the vessel and upper mixing blades for promoting downward axial mixing; by the steps of charging the vessel with the concentrated surfactant and water starting the anchor mixer to establish axial circulation in the contents of the vessel then running the high shear mixer while maintaining the contents at a temperature in the range 34-45 °C for the duration of the mixing.
2. A method as claimed in claim 1, wherein the anchor mixer runs for a period of at least 2 minutes before the high shear mixer is started.
3. A diluted surlactant made by the method of claim 1 or 2, wherein the concentrated surfactant is SLES.
4. A diluted surlactant made by the method of claim 1 or 2, further containing caustic soda at a concentration in the range 0.01 -0.03 wlv%.AMENDMENTS TO CLAIMS HAVE BEEN FILED AS FOLLOWSClaims 1. A batch method of diluting a concentrated foaming surfactant in a vessel (2) of a machine having an anchor mixer (4,10,12) comprising an anchor paddle (10) and upper mixing blades, driven in a first sense, and a high shear mixer (6, 20) driven in the opposite sense, the high shear mixer having a mixing element (20) positioned axially between the anchor paddle (10) in a base of the vessel and the upper mixing blades for promoting downward axial mixing; by the steps of charging the vessel with the concentrated surfactant and water starting the anchor mixer to establish axial circulation in the contents of the vessel then running the high shear mixer during operation of the anchor mixer while maintaining the contents at a temperature in the range 34-45 °C for the duration of the mixing.LI") 2. A method as claimed in claim 1, wherein the anchor mixer runs for a period of at least 2 minutes before the high shear mixer is started. (4 a)