FR2792322A1 - Attaching quinone or indole compounds to talc, useful e.g. as ultra-violet absorbers in cosmetics, by reductive solubilization, application to talc and reoxidation - Google Patents

Abstract

Method for attaching quinone- or indole-type compounds (I) to particles of talc to produce stable composites (A) comprises solubilizing (I) in aqueous reducing medium and adding talc particles to a weight ratio (I):talc of 0.05-2% (corresponding to a uniform monolayer of (I) on all particles). (I) is then precipitated by oxidation in the medium and the solid and liquid phases separated.

Description

METHOD OF FIXING ON MINERAL PARTICLES, IN

  SPECIFICALLY TALC, MICA OR PYROPHYLLITE, OF MOLECULES

  QUINONIC OR INDOLIC TYPE ORGANICS, ESPECIALLY

ORGANIC DYE MOLECULES

  The invention relates to a method for fixing on mineral particles (in particular talc, mica or pyrophyllite) of organic molecules of the quinone or indole type. It makes it possible in particular to obtain a coloration of the mineral particles by fixing on them an organic dye of the quinone 1o or indole type. In another type of application, it allows organic molecules of the quinone or indole type to be fixed on the mineral particles, having a protective function for the epidermis against ultraviolet radiation with a view to

  make dermatological or cosmetic products.

  One of the conventional means for coloring an inorganic powder, in particular talc, consists in mixing therewith a dye powder and in making the mixture homogeneous. However, the two compounds remain separate and independent so that the behavior of the particles of one and the other may differ in certain circumstances. Thus in make-up products, there is a migration of dye particles which may be in contact with the mucous membranes.

affect and irritate these mucous membranes.

  It has been proposed in patent EP 0 565 417 to "couple" an indole derivative and a quinone derivative in the presence of an inorganic filler in order to carry out a reaction leading to colored particles which can serve as pigment. However, the proposed process is complex and requires the use of two types of organic molecules reactive with each other: indole derivative

and quinone derivative.

  The present invention proposes to provide a new method for fixing on mineral particles, in particular talc, mica or pyrophyllite, organic molecules of the quinone or indole type. Its objective is to provide a simple process, making it possible to fix on the particles

  mineral only one type of molecule.

  By "talc" is meant hydrated magnesium silicate or any mixture of phyllosilicate containing this compound. By "mica" is meant aluminous micas such as muscovites, magnesian micas such as phlogopites as well as aluminous or magnesian illites derived from the preceding minerals. By "pyrophyllite" is meant hydrated aluminum silicate, sometimes also called "agalmatolite", or any mixture of silicate containing this compound. In all cases,

  these natural species may contain associated minerals.

  The fixing process according to the invention is characterized in that (a) the organic molecules of the quinone or indole type are dissolved in an aqueous reducing medium, (b) the mineral particles are added to the medium, (c) the organic molecules by oxidation of these in said medium and (d) the solid phase is separated from the liquid phase in order to obtain particles

  mineral composites / organic molecules.

  At the end of the process, mineral composite particles / organic molecules are obtained which have great stability and for which the fixation is irreversible (under most of the usual conditions of use of this type of product). Thus, dissociation tests using organic solvents of different polarities (acetone, ethanol, heptane, butyl acetate, etc.) have not made it possible to break the mineral / organic molecules fixation. It should be emphasized that the process does not require the use of couples of reactive molecules with one another, so that its field of application is not

  limited by this requirement of the aforementioned European patent.

  According to an advantageous embodiment, the organic molecules are solubilized in an aqueous medium made reducing by adding a hydrogen sulfite and raising the pH of the medium by adding a base. The temperature is preferably raised to a value between 50 ° and 60 to promote solubilization and increase the kinetics. The mineral particles are advantageously dispersed in the medium by stirring. Precipitation can then be obtained, after having left the mineral particles and molecules in the aqueous medium for a few minutes, by oxidation in particular by the addition of hydrogen peroxide in the medium or by the diffusion of ambient air (or optionally d 'oxygen) in said aqueous medium. The separation of the solid phase and the liquid phase can then be obtained by conventional operations

filtration and drying.

  The method of the invention is thus very simple to implement, comprising only routine operations, inexpensive. It can in particular be applied to color talc, or mica, or pyrophyllite particles, using as organic molecules an organic dye of quinone or indole type, the reduced form of which is soluble in an aqueous medium. Colored talc, mica or pyrophyllite composite particles are obtained, for which there is no risk of dissociation and therefore no risk of migration or diffusion of the organic coloring molecules since these are directly fixed on the mineral particles. In this application, the relative weight proportion of dye dissolved in the aqueous medium relative to talc, mica or pyrophyllite

  added is substantially between 0.05% and 2%.

  The following examples illustrate the process of the invention and

  the characteristics of the products obtained.

  EXAMPLES 1-3: Process for the Preparation of Talc Colored with

  using three different dyes.

  In a 500 cm3 flask with stirring, 250 cm3 of distilled water and 1 g of the dye indicated in the table are introduced, then the mixture is heated to the temperature of 50-60 C. At this temperature, sodium hydroxide (5 cm3) and 0.6 g of sodium hydrogen sulfite, it is left to react until the color changes

  (reduction of the dye) for a period of the order of a few minutes.

  The talc used in this example is a standard talc (98% pure talc) with an average diameter D50 of 15 microns and a cut-off diameter D95 of

microns.

  100 g of talc are added to the medium, the reaction is left to react for ten minutes, then the oxidation reaction is completed by the addition of hydrogen peroxide (2 to 3 cm3 at 30%), the reaction is left to react for a few minutes, we filter the mixture

  final on buchner, then wash with hot water (30/40 C).

  The colored talc thus prepared is dried in an oven (12 h, 120 C).

  The products thus prepared are characterized from a colorimetric point of view according to the Hunter Lab system (L, a, b): - component L: characterizes the whiteness and the light intensity, - component a: negative, characterizes the green color, - positive, characterizes the color red, - component b: - negative, characterizes the color blue, positive, characterizes the color yellow, Results Products L ab Example Talc without dye 94.7 - 0.89 - 0.24 comparative Example 1 Talc Indanthren blue colored 57.8 - 5.05 -21.92 ("Colloisol CLF", BASF) Example 2 Indanthren red colored talc 60.7 32.0 - 0.34 ("Colloisol FBB", BASF) Example 3 Talc colored with yellow Indanthren 91.6 - 4.5 + 35.5 ("Colloisol SGF", BASF) A clear coloration of the talc is observed whatever the

dye used.

  The behavior of the talc dye thus prepared is studied by subjecting it to conventional Kumagawa-type extractions with solvents.

  following: acetone, ethanol, N-heptane, butyl acetate.

  The components L, a, b are measured after these extractions Products L ab Example Talc without dye 94.7 - 0.89 - 0.24 comparative Example 1 Talc stained with Indanthren blue 57.8 -5.05 -21.92 ( "Colloisol CLF", BASF) Example 2 Talc colored with Indanthren red 60.7 32.0 - 0.34 ("Colloisol FBB", BASF) Example 3 Talc colored with Indanthren yellow 91.6 - 4.5 + 35.5 ("Colloisol SGF", BASF) The color values before and after extraction are

  identical. The dyes are perfectly fixed on the talc.

  EXAMPLES 4-8: Demonstration of the influence of

dye concentration.

  The process is carried out in an identical manner to Example 1.

  g of talc are treated and the dye is Indanthren blue ("Colloisol CLF", BASF). The amount of reducing agent (sodium hydrogen sulfite) is adjusted according to the proportion of dye in accordance with the table below: Dye (g) Hydrogen sulfite (g) Example 4 0.05 0.03 Example 5 0.1 0.06 Example 6 0.5 0.3 Example 7 1.0 0.6 Example 8 3.0 1.8 Results Blue ("Colloisol CLF" (), BASF) Colorant (%) L ab Example Talc without 94.7 - 0, 89 - 0.24 comparative dye Example 4 0.05 86.4 - 3.07 - 7.44 Example 5 0.1 81.7 - 4.3 -10.36 Example 6 0.5 65.4 - 7, 7 - 19.4 Example 7 1.0 57.8 - 5.05 -21.92 Example 8 3.0 47.58 - 2.52 - 21.01 The intensity of the coloring is directly related to the proportion

  of dye compared to talc. Above 1%, the variation is greatly reduced.

Claims (7)

  1 / - Method for fixing on organic particles, in particular talc, mica or pyrophyllite, of organic molecules of quinonic or indolic type, characterized in that (a) said organic molecules are solubilized in a reducing aqueous medium, (b) add the mineral particles to said medium, (c) the organic molecules are precipitated by oxidation of these in said medium and (d) the solid phase is separated from the liquid phase in order to obtain particles   mineral composites / organic molecules.   2 / - Process according to claim 1, characterized in that (a) the organic molecules are solubilized in an aqueous medium made reducing by   adding a hydrogen sulfite and raising the pH of the medium by adding a base.   3 / - Method according to one of claims 1 or 2, wherein   (b) adding the mineral particles to the reducing aqueous medium and dispersing   these in the middle by shaking.   4 / - Method according to one of claims 1, 2 or 3,   characterized in that (c) the organic molecules are precipitated by oxidation thanks to   addition of hydrogen peroxide in the medium.   / - Method according to one of claims 1, 2, 3 or 4,   characterized in that (c) the organic molecules are precipitated by oxidation thanks to   air diffusion in the aqueous medium.   6 / - Method according to one of claims 1, 2, 3, 4 or 5,   in which (d) the solid phase is separated from the liquid phase by filtration and drying.   7 / - Method according to one of claims 1 to 6 for the   fixation on talc, mica or pyrophyllite particles of an organic dye   quinonic or indolic type, in order to obtain colored composite particles.   8 / - Process according to claim 7, characterized in that the relative weight proportion of dye dissolved in the aqueous medium relative to the talc, mica or pyrophyllite added is substantially between 0.05% and 2%.