CZ289422B6 - Method for reducing dehydrating properties of soap, soap-based cleaning composition exhibiting weak dehydrating properties and use of talc for these purposes - Google Patents

Abstract

In the present invention there is described a method for reducing the dehydrating properties of a fatty acid salt soap. In use, the method includes adding to said soap, in order to produce on the skin a film replacing the natural lipid film destroyed or damaged by the soap, talc having the following combined properties: a compacted apparent density substantially lower than 0.70 g/cme3, and a grain size distribution such that the mean diameter Di50 of the grains is substantially lower than 6 microns, and the diameter Di95 is substantially lower than 20 microns.

Description

A method for reducing the dehydration properties of a soap and a soap-based cleaning composition with poor dehydration properties and the use of talc for these purposes

Technical field

The invention relates to a process which makes it possible to reduce the dehydration properties of soaps based on fatty acid salts. It is also within the scope of the invention to use novel cleaning compositions made using this process and to use a type of talc for these purposes.

BACKGROUND OF THE INVENTION

It is known from the prior art that fatty acid toilet soaps have the disadvantage of having a strong dehydrating effect on the skin. This effect is manifested by an unpleasant feeling of dry skin, accompanied by a feeling of tension that occurs several minutes after use when all the water used evaporates and the freshness obtained disappears. In order to reduce the cost of the products and sometimes to increase the sensation of gentleness during washing, standard type talc was used as a soap filler; however, the refinement achieved in use (given by the layered nature of talc) is not associated with a feeling of drying after use, so that these known products also exhibit dehydration properties once the water used has evaporated.

SUMMARY OF THE INVENTION

It is an object of the present invention to reduce the dehydration properties of soaps based on fatty acid salts so as to suppress the discomfort of drying caused by soap after the water used has evaporated.

The process of the invention aims to form a film on the skin during use of the soap, replacing the natural fat film which has been destroyed or damaged by the soap. Indeed, it has been shown that the drying sensation is caused by the destruction or damage of the fat film which protects the epidermis and constitutes a barrier limiting the surface dehydration of the skin. During the use of soap, the fat film is dissolved by the action of tensioactive fatty acids. In the absence of this film until it is re-formed by the epidermis, abnormal dehydration occurs on the epidermis, accompanied by the above-mentioned discomfort (dryness, tension) and the risk of skin damage. The present invention provides a method of forming a stable skin protective film during use of soap, which film replaces the natural fat film in order to limit the surface dehydration of the epidermis until the natural fat film is formed. The process according to the invention consists in adding talc having the following characteristics to the soap produced:

- a bulk density of less than 0,70 g / m ³ ,

- particle size distribution such that the mean grain diameter D ₅₀ is substantially less than 6 µm and the diameter D ₉₅ is substantially less than 20 µm.

The term 'talc' means a mineral hydrated magnesium silicate, a mineral chlorite (hydrated magnesium aluminum silicate) or a mixture of the two, possibly combined with other minerals (dolomite, etc.), or a talc-like substance having analogous properties.

The term "mean diameter D ₅₀ " means a diameter where 50% by weight of the grains have a size smaller than that diameter; "diameter D ₉₅ " means a value where 95% by weight of the grains are less than this size.

-1GB 289422 B6

Powder bulk density defined by AFNOR NFT30-042. In the case of talc, this value provides information on the grain form: with an equivalent particle size distribution, the talc species having the lamellar grains in a very elongated form has a bulk density less than the talc species having the grains in a less elongated form (more spheroid). Thus, at equivalent granulometry 5, this parameter can be considered for talc as a coefficient to assess the form of its particles.

The present invention is based on the following observation observed during a series of comparative trials: a significant reduction in the drying properties of the soap was surprisingly achieved by incorporating talc having grain in a relatively spheroid, less elongated form (i.e. 10 basal / sheath ratio not too high) ), within the limits where the grain size does not exceed the above values.

Preferably, a microcrystalline talc having grains of a more spheroid form is used, wherein each grain is comprised of elementary particles which are bound between each other and these elementary particles of less than or equal to 1 µm have no preferential orientation.

It is also possible to use a lamellar type talc that has been subjected to crushing in order to at least partially break its layers (impact crushing, etc.).

According to a preferred method of applying this process, a microcrystalline talc is used having the following characteristics:

- a bulk density in the range 0,20 to 0,60 g / cm ³ ,

a particle size distribution such that the mean diameter D ₅₀ is in the range 2 to 5 µm and the diameter D 95 is in the range 6 to 14 µm.

Better results were obtained using microcrystalline talc, which was subjected to impact crushing to achieve a bulk density in the range of 0.38 to 0.57 g / cm ³ .

The results obtained are currently difficult to explain satisfactorily. It appears that the characteristics of the talc used (bulk density corresponding to grain form, particle size distribution) lead to good grip and retention of talc on the skin surface, while grains of more lamellar form or larger size are not retained by the surface and are removed by rinsing. Thus, according to the invention, a protective hydrophobic film of talc is formed on the skin surface which has sufficient stability to remain on the skin during rinsing and act as a barrier 35 that restricts the passage of water molecules and thus dehydration of the epidermis until restoration fat film that has been destroyed by soap.

In the context of the present invention, it should be noted that the known skin softening effect of using this soap also relates to the above-mentioned talc forms, and this constitutes an additional advantage of the present invention.

It seems that the best results were obtained when soap was added in the range of 5 to 20% by weight of talc. In addition, talc with an iron content of less than about 1.0% was preferably used in this embodiment to avoid the risk of soap degradation over 45 times (wherein the iron content represents the total amount of iron expressed as Fe ₂ O ₃ ).

The present invention encompasses cleaning compositions with poor dehydration properties, which are made by the above process, wherein talc having the characteristics described above is added to the soap.

-2GB 289422 B6

DETAILED DESCRIPTION OF THE INVENTION

The process for reducing the dehydration properties of a soap and a soap-based cleaning composition with poor dehydration properties will be illustrated in the following examples, which, however, are illustrative only and are not intended to limit the scope of the present invention.

Evaluation methodology used in the examples

All soap samples were evaluated by panel tests.

Prior to evaluation, soap samples were conditioned for 24 hours at 20 ° C and 60% RH. During the evaluation, the temperature of the water used was 40 ° C and the flow rate was 1 liter / minute.

The different soap samples were divided in two and subsequently each sample was independently evaluated by 8 persons (panelists) in each case in a different order of use.

Each soap sample was evaluated 24 times.

Evaluation protocol

- wash your hands with comparative soap (simple soap without additive),

- dry your hands thoroughly with a towel,

- immerse hands in water for 5 seconds,

- soak the test soap and apply its defined amount (10 rotations) to the back of the left hand,

- place the palm of the right hand on the back of the left hand and rub the soap 20 times in a rotary motion,

- rinse hands under running water for 10 seconds without rubbing,

- dry your hands with a paper towel,

- after three minutes evaluate the skin touch.

The following skin parameters were evaluated:

- feeling hydrated,

- feeling dry,

- feeling soft.

The results were graded -2 to +8: the higher the value, the better the result:

Importance of individual evaluations:

- Hydration parameter: -2 not hydrated at all, +8 very hydrated,

- Drying parameter: -2 very dry, +8 not dry at all,

- Fine parameter: -2 is not fine at all, +8 is very fine.

-3GB 289422 B6

Definition of the parameters of added talc (1) Bulk density

The method consists in subjecting a known amount of powder to shaking conditions as defined in AFNORNF T 30-042.

The density of the product shaken off shall be calculated from the ratio of the weight used relative to the shake volume, according to the formula:

M-Mn v

in which:

M is the mass, in grams, of the epruvette containing the powder,

M _o is the weight of the empty tube, in grams,

V is the volume shaken off in cm ³ .

(2) Granulometry

Granulometric analysis was performed using a "Sédigraph 5000" (trademark). The method is based on the measurement of the solid phase concentration (by X-ray absorption) in suspension during gravitational sedimentation. This method is used for powders whose grains have a diameter in the range of 0.5 to 100 µm.

The instrument directly determines the distribution curve, expressed as a percentage of the passing ratio, based on the Stockes average:

- D95 corresponds to the diameter at which 95% by weight of the grains have a smaller diameter than this value,

- D ₅₀ corresponds to an average diameter at which 50% by weight of the grains have a diameter smaller than 35.

Formulations used in the examples:

Formula Soap-free comparative soap Soap with talc Base Soap: PRISAVON brand deposited ref: 9242 in Unichema Intemational 98.6% 87.3% Perfume 1.0% 1.0% Titanium oxide 0.4% 0.4% Talc - 10.0% Added water - M *

* The soap base contains water (of the order of 13%), and the water listed in the table, which has been added with talc, allows the total water content of both formulations to be kept constant.

The talc / soap premix was made in a conventional belt mixer. The final stages of soap production after premixing are commonly performed phases (crushing, refining, extrusion, cutting, pressing).

-4GB 289422 B6

Example 1

This example illustrates a decrease in the dehydration properties of the additive soap.

This example presents a comparison of the talc-containing soap (A) of the invention and the soap-free soap.

Talc A parameters:

- a microcrystalline type which has been subjected to impact crushing,

- D ₉₅ = 8.5 µm

- D ₅₀ = 3.4 pm

- bulk density = 0,5 g / cm ³ .

Results:

Parameters Soap-free comparative soap Soap with talc A (according to the invention) Hydration parameter 2.38 3.75 Drying parameter 3.25 4.46 Fineness parameter 4.29 5.71

The results were analyzed statistically by the Student method. It has been noted that the process of the invention provides a significantly better result than talc-free comparative soap.

Example 2

This example illustrates the effect of particle size distribution.

This example presents a comparison of two soaps containing talc (B, C) and a comparative soap without talc. Talc C did not satisfy its granulometry in the process according to the invention.

Talc (lamellar origin) parameters

talc B according to the process of the invention,

D95 - 7 pm

D ₅₀ = 3 µm, bulk density = 0.44 g / cm ³ .

- talc C not suitable for the process according to the invention,

D95 = 44 pm

D ₅₀ = 18 µm, bulk density = 0.74 g / cm ³ .

Results:

Parameters Soap-free comparative soap Soap with talc B (invention) Soap with talc Hydration 3.83 4.88 3.42 Drying 5.62 6.42 5.46 Softness 5.54 6.29 5.54

-5GB 289422 B6

It has been noted that the process of the invention (talc B) provides significantly better results with respect to the comparative soap without talc and the soap containing talc C, which is not within the scope of the process of the invention.

Claims (8)

PATENT CLAIMS 10 1. A method of reducing the dehydrating properties of a fatty acid salt soap by adding talc to the soap to form a film on the skin during use of the soap, replacing the natural fat film destroyed or damaged by soap, characterized in that the talc has the following characteristics: 15 - a bulk density of less than 0,70 g / cm ³ , - particle size distribution such that the mean diameter D _{50 of the} grains is less than 6 micrometers and the diameter D 95 is less than 20 micrometers. The method of claim 1, wherein the soap bar adds a 20 weight percent talc in the range of 5 to 20%. Method according to either of Claims 1 and 2, characterized in that the soap bar adds talc that has been subjected to crushing capable of at least partially breaking its layers. 25 Method according to any one of claims 1, 2 or 3, characterized in that the soap bar adds talc with an iron content of less than 1.0%. Method according to any one of claims 1 to 4, characterized in that the soap bar adds a microcrystalline talc having the following characteristics: - a bulk density in the range 0,20 to 0,60 g / cm ³ , - particle size distribution such that the mean diameter D50 of the grains is in the range of 2 to 5 micrometers and the diameter D95 is in the range of 6 to 14 mirrometers. The method of claim 5, wherein the microcrystalline talc that has been subjected to impact crushing is added to a density in the range of 0.38 to 0.57 g / cm ³ . 7. Cleaning compositions with poor drying properties, which contain a salt-based soap 40 fatty acids, characterized in that they are additive-containing talc as defined in any one of claims 1 to 6, wherein the composition is capable of forming a film on the skin during use that replaces a natural fat film which has been damaged or destroyed soap. 8. Use of talc having the following characteristics: - a bulk density of less than 0,70 g / cm ³ , - a particle size distribution such that the mean diameter D _J0 grains is substantially less than 6 microns, and the diameter D95 is less than 20 microns, in order to reduce the drying properties of soap based on fatty acid salts, by creating a film that skin replaces the natural lipidic film was damaged 50 or destroyed by soap.