The present invention relates to a process for the deparaffination of crude 2,6,10,15,19,23- hexamethyltetracosane or squalane by cooling and low- temperature separation and to the purified squalane thus obtained.

2,6,10,15,19,23-hexamethyltetracosane or squalane and its various isomers are derivatives of 2,6,10,15,19,23- hexamethyl-2,6,10,14,18,22-tetracosahexene or squalene (spinacene) , an isoprenoid hydrocarbon of the terpene series, precursor of sterols and occurring in shark liver oil and in the unsaponifiable matter of certain vegetable oils, like olive oil.

It has been proposed in European Patent Specification EP-B-0,228,980 (Hispano Quimica S.A.) to isolate squalene from vegetable oil and to convert this into squalane by a rather complicated process involving four process steps. In the last stage the squalane, obtained by hydrogenation of squalene, is deparaffinated, but then still needs to be deodorized.

The deparaffination may be a two-stage process. First a low temperature filtration is applied to remove the higher paraffines, followed by a treatment with urea to form paraffin-urea complexes, which are then separated off. This is a curnbersome procedure. In the first step a solvent is used and temperatures between 0°C and -50°C, preferably between 10°C and -20°C, and the filtration is effected at the crystallization temperature.

Similar deparaffination techniques have been described in Spanish Patent Specifications ES-A-555,113 (8706592) (Tadeval S.A.) and ES-A-550,146 (8701701) (Tadeval S.A). Finally, in French Patent Specification FR-A-2,576,303 (S.A. Derivan) a complicated crystallization process has been proposed for the separation of hydrogenated fatty

acids and squalane. In Japanese patent application JP 06/306387 yet another process is disclosed for purification of squalane. According to this reference, squalane from vegetable matters is, after hydrogenation, subjected to a process in which an organic solvent (ketone and ester type solvents are preferred) is added to the squalane fraction, whereafter the mixture is cooled to -20°C or even down to - 30°C, followed by filtration. The amount of solvents to be used is between one and 20 times as much as the volume of the squalane fraction (5-10 times being preferred) . This huge amount of solvent is disadvantageous from an economical and environmental perspective as well as from a process point of view, as is the low cooling temperature involved.

Thus, it was an object of the invention to provide a process in which paraffins are removed from an oily fraction from vegetable origin, rich in squalane, which process does not involve complicated processing, which process does not involve the addition of huge amounts of organic solvents (in an amount of more than the amount of squalane to be purified) and which does still yield a squalane which is substantially free from paraffins. Substantially free from paraffins is herein to be understood to mean a content of less than 3%, preferably less than 1%, more preferably less than 0.5%, but most preferably less than 0.1% by weight of paraffins, calculated on the total amount of squalane. A further object was that the purified squalane would remain clear upon cooling to temperatures lower than 0°C, preferably lower than -5°C, more preferably lower than -10°C. A further object was that in case the purification would be obtained by filtration, the specific cake resistance would not be unduly high. Yet a further object was that the purified squalane would not contain substantial amounts (or even traces) of organic compounds which are undesirable in

the processing of the squalane in cosmetics.

It has now been found that these objectives can be met by a process for the deparaffination of crude squalane by cooling and low-temperature separation, which is characterized in that the cooling and separation are carried out in the presence of a crystallization modifier, in an amount less than the volume of the crude squalane to be purified.

Preferably, the crystallisation modifier should at least to some extend be soluble in an apolair medium. More preferably, the crystallisation modifier comprises a compound which is obtainable by polymerisation of triglycerides, in which at least part of the fatty acids present in said triglycerides contains either a hydroxyl group or an unsaturated bond which can be oxidised (or both) . Said polymerisation is herein to be understood to comprise polymerisation by linkage through the fatty acid moieties as well as through polymerisation of the glycerol backbone. Dimers, trimers, etcetera are also included. A most preferred crystallisation modifier comprises oxystearin or partial esters of polyglycerol with linearly interesterified castor oil fatty acids (including ricinolate) , the polyglycerol moiety predominantly being a di-, tri- and/or tetraglycerol. In the latter case, a preferred polyglycerol ester is Admul OL 1403, as available from Quest International, the Netherlands, or similar preparations. Oxystearin is known in the art to be a mixture of the glycerides of partially oxidised stearic and other fatty acids obtainable by heating partially hydrogenated cottonseed or soybean oil under controlled conditions, in the presence of air and a suitable catalyst. Oxystearin is commercially known as e.g. Chillox 100 and Durkex 25, as marketed by Vanden Bergh Foods Company, USA.

The crude squalane mixture which is deparaffinated according to the present invention may be obtained by hydrogenation of crude squalene as obtained from vegetable oils, such as olive oil, rice bran oil, but also yeast fat. Preferably, crude squalene is used as the starting material which has been obtained from the acid oils and deodorization condensates obtained in the refining of olive oil. The preferred method is "dry" fractionation, i.e. without the use of solvents, zeolites or urea solutions, in which the crude squalane is cooled down to a value just above or just below the desired cloud point and the solid phase that is formed during this cooling is removed by filtration at the low temperature to which the crude squalane is cooled down.

The filtration can be improved by slow agitation, a slow linear cooling profile and the addition of a filter aid (e.g. Dicalite, Trade Mark, a diatometer or perlite based product) prior to the filtration. The use of filtration aids may lead to unacceptable losses of squalane, however. In general, the crude squalane is preferably first heated to about 65°C (at which stage the crystallisation modifier is added) , to ensure that no premature crystallization of the crystallization modifier takes places before cooling. If solid contaminants are present, the heated crude squalane may be filtrated before starting the cooling treatment. The cooling of the crude squalane is effected preferably whilst stirring and preferably the cooling is effected in two steps, viz. a decrease in temperature to about 20°C in about 30 minutes, followed by the final cooling from 20°C to the desired value below the desired cloud point of the squalane in several hours. In general, the second cooling goes down to a temperature in the range from -25°C to

+10°C, preferably from -10°C to 0°C, in a period of 4 to 16

hours .

The slurry obtained on cooling is then subjected to separation which can be effected by filtration, e.g. by using a filter press, a vacuum filter or a continuous (vacuum) belt filter.

The crystallization modifier is used in an amount from 1 wt ppm to 5000 wt ppm, preferably from 5 wt ppm to 500 wt ppm, most preferably from 20 wt ppm to 200 wt ppm of the crude squalane to be treated. The crystallization modifier may be added to the crude squalane in molten form at for example 65°C after which the mixture obtained is cooled.

The present invention also relates to purified squalane, obtained by the process according to the present invention, having a cloud point of at most 0°C, preferably at most - 5°C, more preferably at most -10°C, most preferably at most -15°C. The present invention also relates to cosmetic preparations comprising this purified squalane.

The invention will be illustrated by the following examples, which should not be interpreted as limiting the scope of the invention thereto.

Example 1

1100 grams of crude squalane, obtained by hydrogenation of crude squalene from olive oil, was heated to a temperature of 65 °C in a 1.5 litre jacketed glass vessel, agitated with a gate stirrer rotating at 65 rpm. The system was held at 65 C for 30 minutes. Next, the crude squalane was cooled in two stages. First, with a speed of 1.5 C/minute to a temperature of 20 C and then with a cooling speed of 0.04 C/minute to the desired end temperature T _e , at which it was stabilized for 3 hours.

After crystallisation at the desired temperature, the crystal-slurry is filtered in a thermostated testfilter using a 40 μm filtercloth (Propex) with a filteraid (Dicalite) . The filter is pressurized with nitrogen.

To quantify the filterability of the system, the weight of filtered squalane was measured with a balance as a function of time. Following the method described by L. Svarovsky in ^■ Solid-liquid separation' (Butterworth & Co Publishers Ltd, London, 1979), chapter 9, the specific cake resistance can be calculated, which is a measure for the flow resistance caused by the crystals deposited on the filter.

In order to compare the compressibility of the filtercake and filterability at different temperatures, experiments are done at different temperatures (0 and -10 °C) and different filtration pressures (0.5. and 2.0 bar). The filtration-results thus obtained are plotted in table 1.

Example 2

In order to establish the ideal filtration characteristics, the filtrate obtained from example l was filtered again over the filtercloth with filteraid. The filtration-results thus obtained are plotted in table 1.

Example 3

The same method was followed as described in example 1. At the temperature of 65 °C, oxystearin was added to the crude squalane in an amount of 0.01 % by weight. It is observed by microscopy that the crystals formed in squalane with oxystearin are larger and have another shape that those formed in the crude squalane from example l. The filtration-results thus obtained are plotted in table 1. The cloud points of the filtrates from this example and from example 1 were measured by the ASTM D2500 method (see: •Standard methods for analysis and testing of petroleum and

related products', Institute of Petroleum, London, 1993, vol.l.) and were found to be comparable.

Example 4 The same method was followed as described in example 1. At the temperature of 65 °C, Admul OL was added to the crude squalane in an amount of 0.1 % by weight. It is observed by microscopy that the crystals formed in squalane with Admul WOL are larger and have another shape that those formed in the crude squalane from example 1. The filtration-results thus obtained are plotted in table 1.

Table 1 examp system specific cake resistance (10 ⁹ le m/kg)

0.5 bar 2.0 bar filtration filtration pressure pressure

τ _e = 0 τ _e = " τ _e = 0 ^T e = ^" °C 10 °C °C 10 °C

1 crude 6 55 15 154 squalane

2 purified 0 0 0 0 squalane

3 crude 1 1 1 1 squalane with 0.01 w% oxystearin

4 crude 3 9 4 8 squalane with 0.1 % Admul WOL