Organogels Allowing Reduction And Control Of The Evaporation Of Volatile Organic Liquids

Abstract

The invention relates to chemical compositions in the form of an organogel, comprising a gelled organic liquid, comprising or consisting of a volatile organic liquid, and at least one resin acid. The invention also relates to a method for producing same, and the use of same to reduce and control the evaporation of the contained volatile organic liquid.

Claims

1- Composition in the form of an organogel of an organic liquid comprising at least one resin acid.

2- Composition according to claim 1, characterized in that the organogel is composed of an organic liquid, comprising or consisting in a volatile organic liquid and an organogelator.

3- Composition according to claim 1 or 2, characterized in that the organic liquid, comprising or consisting of a volatile organic liquid, is chosen from among the group made up of essential oils, organic solvents, pheromones with fatty chains, hydrocarbons and mixtures thereof.

4- Composition according to claim 1 or 2, characterized in that the organic liquid is a volatile organic liquid and is chosen from among the group made up of essential oils, volatile organic solvents, pheromones with fatty chains, hydrocarbons and mixtures thereof.

5- Composition according any one of claims 1 to 3, characterized in that the organic liquid comprises a volatile organic liquid and a nonvolatile organic liquid chosen from the group of vegetable oils, mineral oils, oils of cosmetic interest and mixtures thereof.

6- Composition according to any one of claims 1 to 5, characterized in that the organogelator is chosen from among the group made up of vegetable waxes, animal waxes, paraffin waxes, fatty acid derivatives, fatty acid salt derivatives, and more particularly 12-hydroxystearic acid, used alone or in mixture.

7- Composition according to claim 6, characterized in that the vegetable or animal wax is chosen from among the group consisting of candelilla wax, carnauba wax, sunflower seed wax, beeswax, rice bran wax sugar cane wax, grape seed wax, jojoba wax, sorghum seed wax, ouricury wax, pea leaf wax, potato leaf wax, esparto wax, ocotillo wax, Balanophora wax, Annona squamosa wax, sea rye wax, cherry laurel wax, oak wax, mimosa wax, orange blossom wax, jasmine wax, rose wax, hemp wax, apricot wax, tuberose wax, orange wax, sweet almond wax or pine needle wax.

8- Composition according to any one of claims 1 to 7, characterized in that the quantity by weight of organogelator in the organogel is comprised between 1 and 30%.

9- Composition according to any one of the preceding claims, characterized in that the resin acid is chosen from among the group made up of abietic resin acids.

10- Composition according to claim 9, further characterized in that the abietic resin acids are chosen from among the group made up of abietic acid, neoabietic acid, dehydroabietic acid, palustric acid and mixtures thereof.

11- Composition according to any one of the preceding claims, characterized in that the resin acid is in the form of a plant resin or a mixture of plant resins.

12- Composition according to claim 11, characterized in that the plant resin is chosen from among the group made up of pine resin, rosin, Sondarac resin, Dammar resin, mastic gum and mixtures thereof.

13- Composition according to any one of the preceding claims, characterized in that the quantity by weight of resin acid in the organogel is comprised between 0.5 and 10%.

14- Use of a composition according to any one of the preceding claims to reduce the volatility of the organic liquid, comprising or consisting of a volatile organic liquid, contained in the organogel.

15- Use according to claim 14 in which the organic liquid, comprising or consisting of a volatile organic liquid, is an inflammable hydrocarbon in order to limit the risks of explosion.

16- Use according to claim 14, in which the organic liquid, comprising or consisting of a volatile organic liquid, is a pheromone, in particular a fatty chain pheromone or a mixture of pheromones, in particular fatty chain pheromones, for the controlled diffusion of this pheromone or this mixture of pheromones.

17- Use according to claim 14, in which the organic liquid, comprising or consisting of a volatile organic liquid, is chosen in the group of liquid insecticides or insect repellents, anti-fungal, anti-viral or anti-bacterial agents for the controlled diffusion of this organic liquid.

18- Insecticide or insect repellent formulation comprising a composition according to one of claims 1 to 13, in which the organic liquid, comprising or consisting of a volatile organic liquid, is endowed with insecticidal or insect repellent properties.

19- Antibacterial formulation comprising a composition according to one of claims 1 to 13, in which the organic liquid, comprising or consisting of a volatile organic liquid, is endowed with antibacterial properties.

20- Antiviral formulation comprising a composition according to one of claims 1 to 13, in which the organic liquid, comprising or consisting of a volatile organic liquid, is endowed with antiviral properties.

21- Preparation method for a composition according to one of claims 1 to 13 comprising the steps of: a) Preparation of a mixture comprising an organogelator, an organic liquid, comprising or consisting of a volatile organic liquid, and liquid at room temperature, and at least one resin acid. b) heating in order to solubilize all the ingredients, c) cooling of the mixture to room temperature in order to form an organogel.

Description

[0111] FIG. 1: Residue at 5 hours after a TGA experiment at 30 C. of the effect of gelation of a eucalyptus essential oil.

[0112] FIG. 2: Effect of gelation on the volatilization of an EO. Eucalyptus (15% by mass organogelator).

[0113] FIG. 3: effect of the addition of rosin (2 or 5%) on eucalyptus EO gelled by carnauba wax (15% by mass)

[0114] FIG. 4: Effect of gelling (15% HSA or candelilla wax) on a soybean oil/EO mixture. eucalyptus (50-50%).

EXAMPLES

Preparation of the Organogel.

[0115] Fixed concentrations of gels are obtained by adding weighed quantities of organogelator (vegetable wax and/or 12-hydroxystearic acid) with the optional addition of resin acids in the form of plant resin or pure resin acids, to different eucalyptus, thyme or lavender essential oils. The mixture is heated to a temperature above the gel point, generally around 23 to 40 C. This temperature varies according to the nature and quantity of ingredients of the organogel. The solution is cooled to room temperature and a gel is obtained. The state of the gel is confirmed by the inverted vial test.

[0116] Table 1 summarizes the preparation conditions of the various organogels.

TABLE-US-00001 TABLE 1 Tdegel Hdegel Tgel Hgel Code Volatile compound Organogelator ( C.) J g.sup.1 ( C.) J g.sup.1 AH61 Eucalyptus EO 7% HSA 23 1.9 23.8 1.3 AH61 Eucalyptus EO 15% HSA 37.5 7.7 41.6 3.6 AH61 Thyme EO 15% car Not visible 35.9 2 AH61 Thyme EO 15% HSA Several max at 2 max at 31; 37.5 and 27.47 52 C. AH61 Lavender EO 15% car Not visible 2 max at 37.51.4 AH61 Lavender EO 15% HSA 33.6 9.8 2 close 8.4 max 39.5 AH67 Eucalyptol 15% HSA 26.4 3.3 27.2 2.2 AH67 Hent 30.2 2.6 36.2 4 AH67 15% can 28 2.5 33.4 3.3 AH67 Thyme EO 15% can No signal AH67 Lavender EO 15% can No signal LL06 Eucalyptus EO 15% hent 27.4 3.8 2 close 4.1 2% rosin max 33.1 LL06 Eucalyptus EO 2% rosin LL06 Eucalyptus EO LL06 Eucalyptus EO 15% HSA 29.8 2.6 26.8 1.7 2% rosin LL06 Eucalyptus EO 15% can 31 5 32.8 1.8 LL06 Eucalyptus EO 15% car No signal 2 max at 1.8 34.1 0.7 26.2 AH89 Eucalyptus EO 15% hent 30.8 1.8 Broad 2 2% Abietic signal acid 32.6 Hent: Hentriacontane Car: Carnauba wax Can: Candelilla wax

[0117] Other organogels have been prepared in a similar manner with mixtures of essential oil and soybean oil and/or by using other organogelators such as steric acid, sodium stearate, sunflower oil, paraffin wax, pine needle wax or beeswax.

[0118] The gelling agent called organogelator is capable of self-organizing to form filaments or crystallites. These fibers or crystallites intertwine or interconnect to form a three-dimensional organization. This network traps the organic liquid and prevents it from flowing. From the macroscopic viewpoint, the liquid has become solid. Gelling is a reversible means of creating a material from a liquid, but not changing its chemical composition. The self-organization of the organogelator consists of noncovalent interactions such as hydrogen bonds or van der Waals forces.

[0119] Organogelators are able to gel any sort of organic liquid even at relatively low weight concentrations (typically a few percents by weight). 12-hydroxyoctadecanoic (or 12-hydroxystearic acid, HSA) is an organogelator that gels by forming a 3D network of intertwined fibers. Waxes, such as carnauba (car) and candelilla (can) waxes are also organogelators, but which gel by forming an interconnected crystallite network.

[0120] Different essential oils were gelled by three organogelators. The gel points were determined. The volatilization of pure or gelled essential oils was measured by thermogravimetric analysis (TGA) at a fixed temperature. The three essential oils tested were eucalyptus (Eucalyptus globulus, Phytosun aroms), lavender (Lavandula officinalis, Phytosun aroms) and thyme (Thymus vulgaris, Phytosun aroms). The case where an essential oil is diluted/dissolved in a nonvolatile organic liquid was also tested: glyceryl trioctanoate or soybean oil were chosen.

[0121] The organogelators tested are 12-hydroxystearic acid and vegetable waxes, in particular carnauba and candelilla wax. These two vegetable waxes are used in the cosmetic and agribusiness industries. These vegetable waxes are complex mixtures of natural compounds. Carnauba wax contains mainly fatty acid esters (80-85%), fatty alcohols (10-15%) acids (3-6%) and hydrocarbon chains (1-3%). A particular feature of carnauba wax is the presence of a large amount of diol esters (around 20%), hydroxylated fatty acids (around 6%) and cinnamic acid (around 10%) which is an antioxidant. Carnauba wax has a melting point of 78 to 85 C., which is one of the highest of the waxes of natural origin. Candelilla wax is made up of hydrocarbons (approximately 50%, with a chain length of 29 to 33 carbon atoms), esters, free fatty acid alcohols and resins. Its melting point is 68 to 70 C. The main compound of candelilla wax is a linear alkane with 31 carbon atoms, hentriacontane (hent); this pure compound is also tested as an organogelator.

Measuring Volatilization by Thermogravimetric Analysis TGA.

[0122] A sample of known mass is placed in a crucible under controlled atmosphere and controlled temperature. The variation of the sample mass is measured over 5 hours. The mass of the residue is expressed in percentage of the initial mass. The experiments are conducted at 30 or 40 C. This mass measurement is precise, we believe the experimental error here to be 3%.

Results

[0123] After 5 hours of experimentation the eucalyptus essential oil residue is 7% by mass; 93% of the oil has volatilized. The lavender and thyme essential oils are less volatile at 30 C. since the residues after 5 hours are 53 and 54%, respectively.

[0124] When the essential oil is gelled, we need to do a correction relative to the raw results. We consider the organogelator not to be volatile. To express the proportion of essential oil volatilized relative to the quantity initially introduced, it is necessary to subtract the mass of the organogelator. In FIG. 2, the eucalyptus essential oil is gelled with 15% by mass of HSA; it is volatilized to 79% after 5 hours. If the correction is made, the volatilization rate of the essential oil is calculated at 93%. This value may then be compared to the pure essential oil experiment; in the rest of this disclosure, only the corrected values will be reported. Note that the HSA-based organogel does not change the volatilization properties of the eucalyptus essential oil: 93% volatilization, whether gelled or not. Also, carnauba wax does not reduce the volatilization of eucalyptus essential oil. On the contrary, candelilla wax has a very pronounced effect since no more than 4% of the oil is volatilized. In summary, while nearly all of the eucalyptus essential oil is volatilized after 5 hours at 30 C., once gelled by the candelilla wax, it practically no longer volatilizes.

[0125] The mass percent of candelilla wax used to gel eucalyptus EO has an impact on the gel volatilization. By increasing the percentage of organogelator, the volatilization of the EO is further delayed.

[0126] Two other essential oils (lavender and thyme) were gelled by candelilla wax and tested by TGA.

[0127] Lavender essential oil volatizes to 37% after 5 hours at 30 C. Once gelled with candelilla wax, it only volatizes to 5% under the same conditions. In the case of thyme essential oil, which volatilizes to 43% after 5 hours at 30 C., gelation by candelilla wax reduces these losses to 8%.

[0128] These first volatilization measures have clearly shown that gelling alone does not noticeably reduce the volatility of an essential oil. This singular result obtained during gelling by candelilla wax may initially be explained by its composition.

[0129] Carnauba wax is extracted mechanically from the leaves of a Brazilian wax palm, and HSA a purified synthetic product. In contrast, candelilla wax is obtained artisinally, from a Mexican spurge (Euphorbia antisyphilitica) by a collection of chemical extraction processes. As a result, this wax contains resin residues (around 2% by mass) in addition to cuticular waxes; they are resin acids such as abietic acid.

[0130] The influence of natural resins on the volatility of an essential oil and synergy with organogelation:

[0131] The particularly noteworthy effect of gelling with candelilla wax led to testing the effect of natural resins on reducing volatility. In a first step, crude pine resin (Pinus pinaster), rosin which is the solid resin obtained after distillation of terebenthene), and abietic acid, which is a triterpenoid, the primary component of rosin, were used.

[0132] Gelling by hentriacontane (primary constituent of candelilla wax) or HSA alone did not reduce EO volatilization (93%). A substantial synergy effect of resin is observed when the EO is gelled with hentriacontane (15% by mass) since the volatilization rate is comprised between 27 and 12% depending on the resin tested. In the case of gelling with HSA, the effect is less marked with a volatilization of 78% with rosin.

[0133] In the case of gelling of eucalyptus EO by HSA (15% by mass), the quantity of resin added was tested. Note that the volatilization of EO may be reduced by increasing the amount of resin. In this case, a rate of 2 to 8% reduces volatilization from 78 to 56%.

[0134] All of these results underline the benefit of the invention in the field of controlling the volatility of essential oils or organic liquids. Reducing this latter by adding natural resins, gelling by candelilla wax or the addition of organogel resins allows extending the use of essential oils and reducing the inflammability of certain organic liquids (e.g. kerosene).