Title:
Coal tar extract with a reduced content of hydrocarbons and dermatological and cosmetic compositions containing the same
Kind Code:
A1


Abstract:
The invention concerns a coal tar extract with reduced polycyclic aromatic hydrocarbon content and a method for obtaining same using two sequentially linked distillation systems. The invention also concerns cosmetic and dermatological preparations containing said resulting coal tar extract.



Inventors:
Navarro, Roger (Pamiers, FR)
Application Number:
09/916560
Publication Date:
12/27/2001
Filing Date:
07/27/2001
Assignee:
NAVARRO ROGER
Primary Class:
Other Classes:
424/401, 424/400
International Classes:
A61K8/96; A61K8/97; A61K35/04; A61Q19/00; B60K15/05; C10C1/16; C10C3/06; A61Q5/00; (IPC1-7): C10G1/00; A61K7/00
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Primary Examiner:
LAMM, MARINA
Attorney, Agent or Firm:
THE FIRM OF HUESCHEN AND SAGE (SEVENTH FLOOR, KALAMAZOO BUILDING 107 WEST MICHIGAN AVENUE, KALAMAZOO, MI, 49007, US)
Claims:
1. Coal tar extract, characterized in that its maximum content of polycyclic aromatic hydrocarbons is about ten parts per million (ppm) and its maximum content of benzo(a)pyrene is about a few ppm.

2. Coal tar extract according to claim 1, characterized in that its content of polycyclic aromatic hydrocarbons is less than about 4 ppm and its content of benzo(a)pyrene is less than about 1 ppm.

3. Process for obtaining a coal tar extract according to claim 1 or 2, from crude coal tar, characterized in that it uses at least two distillation systems connected in series.

4. Process according to claim 3, characterized in that the first system is a thin-film evaporator and/or the second system is a distillation column.

5. Process according to claim 4, characterized in that the distillation on a thin-film evaporator is carried out under a pressure of 5 to 7 mmHg, between 198° C. and 200° C., and at a crude coal tar feed rate equal to 18 to 19 kg/h.

6. Process according to claim 5, characterized in that the distillation on a distillation column following distillation on a thin-film evaporator is carried out at from 260° C. to 320° C.

7. Cosmetic or dermatological compositions containing a coal tar extract according to claim 1 or 2 or obtained by the process according to one of claims 3 to 6.

8. Cosmetic or dermatological compositions according to claim 7, characterized in that they contain 0.1 to 10% by weight of coal tar extract.

Description:
[0001] The present invention relates to a coal tar extract with a reduced content of polycyclic aromatic hydrocarbons, to a process for obtaining it and to dermocosmetic compositions containing it.

[0002] The term “coal tar” means the by-product of the destructive distillation of bituminous coal distilling between at 300 and 370° C. This is a black viscous liquid whose characteristic odor resembles that of naphthalene.

[0003] The term “coal pitch” means the residue from the distillation of coal tar.

[0004] Crude coal tar contains a large proportion of polycyclic aromatic hydrocarbons (PAH) of the order of 100,000 ppm. Among the predominant PAHs which have been identified are fluoranthene, pyrene, anthracene, phenanthrene, fluorene, 1,2-benzofluorene, 2,3-benzofluorene, 1,2-benzanthracene, chrysene, benzo(k)-fluoranthene, benzo(a)fluoranthene, benzo(b)fluoranthene, benzo(e)pyrene, benzo(a)pyrene (BaP), indeno(1,2,3,c,d)pyrene, 1,2,5,6-dibenzanthracene, benzo(6)chrysene and benzo(g,h,i)perylene, the last thirteen compounds having toxic properties.

[0005] Coal tar is commonly used in antidandruff treatment, in the treatment of certain types of dermatitis such as eczema, lichenification and psoriasis. Before being incorporated into dermatological compositions, coal tar undergoes a purification intended to make it colorless, odorless and substantially free of irritant properties.

[0006] Many processes for purifying coal tar are described in the literature.

[0007] Patent U.S. Pat. No. 3,766,052 (Warner Lambert Co.) published on Oct. 16, 1973 describes a process for purifying commercially available coal tar, which comprises mixing the said coal tar with a C15-C22 fatty acid ester, adding squalane or squalene, and recovering the purified coal tar in the form of the supernatant liquid. The coal tar obtained has a viscosity of between 10 and 50 mPa.s and a density at 25° C. of between 0.88 and 0.95. It is used as an active ingredient in dermatological compositions in a proportion from 1 to 10% by weight.

[0008] Patent U.S. Pat. No. 3,928,579 (Warner Lambert Co.) published on Dec. 23, 1975 describes a process for purifying crude coal tar, which consists:

[0009] 1) of an extraction with a volatile solvent or mixture of solvents whose kauri butanol number is less than 75 and whose boiling point is less than 80° C.,

[0010] 2) of a filtration, and then

[0011] 3) of an evaporation of the volatile solvent(s).

[0012] The solvents used are C3-C6 alkanes or CFCs.

[0013] The purified coal tar is incorporated in the dermatological composition.

[0014] Patent application JP-55 153 710 (Fujunaga Seiyaku) published on Nov. 30, 1980 describes a cosmetic skin composition containing, as active ingredient, purified tar obtained by distillation of mineral, animal or plant tar under reduced pressure, by diazotization and then by hydrolysis or heating. The tars used are coal tar and soybean tar.

[0015] The distillation carried out from 50 to 120° C. under a vacuum of 5-10 mmHg allows the mutagenic properties of the tar to be reduced by a factor of 20. Diazotization with an excess of nitrite followed by an increase in temperature and optionally a hydrolysis makes it possible to reduce the mutagenic properties of the tar by a factor of 90.

[0016] Among the PAHs contained in coal tar whose toxic properties have been recognized, it has been found that BaP exhibits carcinogenic properties in the event of prolonged use.

[0017] Patent application EP-A-465,434 describes tar oil obtained by fractional distillation of naphthalene oil on three rectification columns in series between 230 and 330° C. The naphthalene oil itself is obtained from the distillation of coal pitch.

[0018] At the experimental stage, this extract can contain a BaP percentage of less than 2 ppm (parts per million). However, at the industrial scale, a BaP percentage of about 20 ppm will be selected.

[0019] The present invention relates to a coal tar extract with a reduced content of both PAH and BaP.

[0020] The coal tar extract according to the invention is characterized by a maximum PAH content of about ten ppm and by a maximum BaP content of about a few ppm.

[0021] The coal tar extracted according to the invention is preferably characterized by a PAH content of less than about 4 ppm and a BaP content of less than about 1 ppm.

[0022] The present invention also relates to a process for obtaining the said coal tar extract from crude coal tar which uses at least two distillation systems connected in series.

[0023] A thin-film evaporator is advantageously chosen as the first distillation system, and/or a distillation column as the second system.

[0024] The distillation on a thin-film evaporator is carried out under a pressure of 5 to 7 mmHg, at a temperature of between 198 and 200° C., and at a crude coal tar feed rate equal to 18 to 19 kg/h.

[0025] The column distillation following distillation on a thin-film evaporator is carried out at between 260 and 320° C.

[0026] The distillation yield according to the invention using a thin-film evaporator coupled to a distillation column is between 20 and 25% by weight.

[0027] Crude coal tar is commercially available and corresponds to the definition in the French Pharmacopea and/or in the US Pharmacopea. Its respective contents of PAH and of BaP are about 93,000 and 2000-10,000 ppm.

[0028] The present invention relates to cosmetic or dermatological compositions containing the coal tar extract according to the invention, preferably in a proportion of from 0.1 to 10% by weight.

[0029] A cosmetic or dermatological composition containing 0.5% of coal tar extract with 1 ppm of BaP has respective contents of PAH and BaP of about 15 and 2 ppb (parts per billion).

[0030] The said compositions are proposed under the same therapeutic indications as crude coal tar.

[0031] The examples which follow illustrate the invention without limiting its scope. 1

Example 1: SHAMPOO
PURIFIED WATER qs100g
PULVERIZED SALICYCLIC ACID1.50g
UNDECYLENIC DERIVATIVE1 to 3g
QUATERNARY POLYMER0.5 to 1g
ETHOXYLATED SODIUM ALKYL SULFATE9g
POLYSORBATE-205 to 7g
FATTY ACID ETHANOLAMIDE
PEG-6000 DISTEARATE5g
ALKYLAMIDO BETAINE1.5g
COCOAMPHODIACETATE3.5g
DISODIUM EDTA0.2g
20 POE SORBITAN MONOLAURATE5g
FRAGRANCEQS
DYEQS
COAL TAR0.1 →g
2.50
Example 2: SHAMPOO
WATER qs100g
SODIUM LAURETH SULFATE8g
POLYSORBATE7g
PEG-150 DISTEARATE4g
SODIUM UNDECYLENAMIDO
MEA-SULFOSUCCINATE3g
SODIUM COCOAMPHODIACETATE3g
SALICYCLIC ACID1.5g
FRAGRANCE0.5g
T.E.A.-HYDROLYZED COCOYL-COLLAGEN1g
COAL TAR0.1 → 1g
Example 3: LOTION
WATER qs100ml
SD-ALCOHOL 39-C63ml
FRAGRANCE0.20g
VINYL ACETATE/CROTONIC ACID COPOLYMER0.15g
PEG-13 OCTANOATE0.10g
LAURYLPYRIDINIUM CHLORIDE0.05g
COAL TAR0.1 → 1g
Example 4: CREAM
WATER qs100g
PEG-40 SORBITAN LANOLATE7.5g
PARAFFIN5g
PROPYLENE GLYCOL5g
CETYL ALCOHOL3g
POLYSORBATE3g
LANOLIN2g
SALICYCLIC ACID1.5g
FRAGRANCE0.4g
COAL TAR0.1 → 3g
Example 5: OIL
MINERAL OIL qs100g
DIBUTYL ADIPATE15g
CAPRYLIC/CAPRIC TRIGLYCERIDE10g
COAL TAR0.1 → 2g
Example 6: SYNDET
SODIUM HEMISULFOSUCCINATE qs100g
SODIUM ISOTHIONATE20g
WAX OF MINERAL ORIGIN12g
CETYL ALCOHOL13g
WHEAT STARCH20g
PINE TAR0.3g
CADE TAR0.3g
SALICYCLIC ACID2g
ZINC OXIDE5g
COAL TAR0.1 → 2g
Example 7: MOUSSE
DEMINERALIZED WATER qs100g
GUAR GUM0.10g
JOJOBA OIL2g
ETHYLHEXYL P-METHOXYCINNAMATE1g
VINYLPYRROLIDONE/DMAE METHACRYLATE1g
PVP HEXADECENE COPOLYMER2g
DIMETHYL/TRIMETHYL-POLYSILOXANE1g
CETRIMONIUM BROMIDE0.40g
FRAGRANCE0.15g
COAL TAR0.1 → 2g
Example 8: EMOLLIENT SOLUTION
PROPYLENE GLYCOL qs100g
CADE TAR10g
PINE TAR10g
POLYSORBATE20g
POLYETHOXYLATED COCONUT FATTY ESTERS10g
POLYETHOXYLATED ALKYLPHENOL10g
FRAGRANCE1g
COAL TAR0.1 → 5g
Example 9: GELLED BODY OIL
CAPRYLIC/CAPRIC TRIGLYCERIDE20 → 30g
MINERAL OIL36g
PETROLATUM15g
PEG-40 SORBITOL HEXAOLEATE8g
QUATERNIUM-18 HECTORITE5g
HYDROGENATED TALLOWETH-60
MYRISTYL GLYCOL5 g
FRAGRANCE0.5g
BENZOIC ACID0.3g
PROPYL GALLATE0.02g
COAL TAR0.1 → 2g