CA1230055A - Solid powder preparation and process for preparing same - Google Patents

Abstract

Abstract of the Disclosure Solid powder preparations containing one or several fil-ler(s), one or several fatty and waxy component(s), one or sever-al cosmetically or medically active ingredient(s) and or colorant(s), one or several evaporable non-toxic hydrophobic solvents and, optionally, further conventional additives may be prepared by casting, if non-hygroscopic flowable organic or inorganic solids having a particle size of from 5 to 50 µm in diameter are used as the filler(s).

Description

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The present invention relates to solid powder preparations for cosme-tlc and medical purposes which contain one or several filler(s), one or several fatty and waxy component(s), one or several active ingredient(s) and or colorant(s), one or several evaporable non-toxic hydrophobic solvents and, optionally, further additives, as well as processes for the preparation thereof.
Pigment-dyed powder compositions have been used for cosmetic purposes, namely for improving the complexion and emphasizing the beauty ideal, for centuries. Said powders were originally produced in the form of loose powders, later also in the form of crayons or compacts. The powder bases were mostly fillers such as talc, kaolin, chalks of different fineness, alkaline earth carbonates, uncolored oxides of aluminium, titanium, zinc, metal soaps such as the stearates or myristates of aluminium, magnesium and zinc. The most various kinds of starches, but also silk powder and celluloses served as the binders.
Powder stones were prepared by stirring the colored pig-ments and fillers with a binder such as calcium sulfate inwater, pouring the mixture in shallow pans and allowing it to dry in the air. The thus obtained powders were applied by means of a moist sponge. Those stones do by no means meet the standard requirements for today's makeup preparations and, thus, the production thereof has been stopped long ago.
For about thirty years there have been exclusively used so-called compact powders which are obtained by compression of flowable powder materials :in metal pans (also called tablets) at pressures between about 20 and about 50 bar. The pressure to be applied for the compression will individually depend on the specific recipe ox the powder composition to be compressed, for example on the hydrocolloids or low-viscous carboxymethyl -- 1 -- , . I,.

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celluloses used ln -the binder and the degree of moisture there-of and the portion and compressive behavior of the colorant and filler pigments.
In the preparation of said compact powders there is required a minimum pressure to be applied in order to obtain powder tablets that will resist breakage. However, a too high compression will result in the formation of products that are too hard and too compact so that they will hardly release any powder. On the other handr if the pressure applied to effect the compression is too low, then the properties of conveying and handling the tablets is reduced to the end of complete use lessness. The compression step must be followed by a process step of sterilization. The pressed pans must be carefully wrapped and packaged for conveyance so that they may be inserted by hand into the final package boxed without mechanically damaging the sensitive surface. From the aforementioned pacts there will be apparent that the preparation of materials meet ing high quality standards involves high reject rates and, hence eventually very high production costs.
From the Canadian Patent No. 1,125,659 there has been known a process or preparing solid powder compositions by stirring fatty alcohols having from 12 to 20 carbon atoms, a finely divided filler and an evaporable siloxane at an elevated temperature to give a fluid composition, casting said com- ;
position into the desired molds, and subsequently evaporating the excess of the siloxane. The products thus obtained, although they exhibit some advantages over conventional wax pro-ducts were easier to produce, showed an appearance which was by no means acceptable for present-day requirements. Namely, ln the course of the evaporation of the solvent said products underwent unsightly cracking and scaling off which the con-sumer would never Dave been ready to accept.

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Thus, for the production of cosmetic articles -there was developed a process wherein the Eluid compositions according to the Canadian Patent Jo. 1,125,659 were inversely cast into molds having a lattice at the bottom thereof from which the evaporation of the solvent could take place from the bottom; cf.
U.S. Patent No. 4,337,859. The undesired migration of the fatty alcohols upon evaporation of the solvent resulted in a se undesired hardening of the powder cake on the surface thereof.
In the process according to the U.S. Patent Specification No.
4,337,859 said effect is exploited to more strongly attach the finished composition to the lat-tice at the bottom.
It will be plausible that neither the composition according to the Canadian Patent No. 1,125,659 nor the method of process-ing same according to the U.S. Patent Specification Jo. 4,337,859 were suitable to displace the previously employed tablets pro-duced by powder pressing in the market.
It is an object of the present invention to develop solid powder preparations which are preparable in a manner similar to that ox the cast powder preparations according to the Canadian Patent No. 1,125,659, which, however, are more readily to be processed and directly yield products that with respect to their quality are comparable to conventional compact powders.
Said object, surprisingly, can be attained by a solid powder preparation containing -a) one or several filler(s), b) one or several fatty and waxy component(s), c) one or several active ingredient(s) and or colorant(s), d) one or several evaporable non-toxic hydrophobic solvents and, e) optionally, further additives, ;~, 19~_~
~.~3C3 It~5~i which is ch.~r~cteri~ed in th.~t the fillerts) col~prise~s) ta) non-h~groscopic Elowable orqanic ox inorganic solicl(s) hiving .
particle size of from 5 to 5U in cliameter.
Said results were not foreseeable, since the artisan hod so far assumed that all powders would require the simultaneous use of silicates having a plate-like crystalline structure such as talc, mica etc. in order to provide a pleasant soft powder spreading. There has now been found that hydrophobic flowable organic or inorqanic solids having a particle size of from 5 to 50 em in diameter are also suitable to ensure a pleasant soft feeling of powder spreading and, moreover, will allow the solvent to evaporate without causing the composition to bloat and crumble away at its surface. Thus, the solid powder composition according to the invention can be prepared by stirring the mixture of the components a) through e) with an excess of solventls) at a tem-perature in excess of 40~C to give a fluid composition, casting same into molds of the desired shapes t evaporating the excess of the solvent(s) and, optionally, treating the surfaces of the products thus obtained with a pressure of less than 10 bar.
It is astonishing that the surface of the solid powder preparations having thus been obtained is smooth and uniform.
However, if desired, the surface can be provided with some deco-rative pattern by employing a low elevated pressure which is preferred to be from 3 to 7 bar. Such~decorative patterns allow a simple check of whether or not the powder composition has already been used or is still intact. Said low elevated pressures which are only applied to the surface are also endured by conventional molds without damage. according to the invention, the mold may be subject to nearly any optional variation so that there is no longer a limitation to the standardized tablets.

As the non~hygroscopic flowable organic or inorganic solids, there may basically be used all powders made of polyethylene, !IC:-t'~
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polypropylene, ~o1~vinvl~!rrolidolle, polyamide, jut aL50 hvdrophobic salts such as tricalcium phosphate. said prot1uct~"
more specifically, are flowable when they consist of sph~ical or nearly spherical particles. Particularly suitable ore those powders which have mostly originated from a relatively narrow sieve fraction or which, due to the production process thereof, have a particle size distribution curve that is as narrow as possible. Such powders do not tend to agglomerate and will ensure a particularly good and faultless processability in combination with very good properties of the final product.
Thus, those powders are preferred at least 70 per cent of which have a particle siæe of from 10 to 25 em in diameter.
The amounts of all of the fillers employed aecording to the inverltion is not eritieal. Amounts of from 10 to 80% by weight ean be used. However, the optimum amount will depend on the types and amount of the other components. The same holds for the fatty and waxy components whieh, on the one hand, are to effect a suffieient bonding of the solid powder preparation, whieh, howev-er, are to be selected so khat the powder applied to the skin will slur or migrate as little as possible. The fatty and waxy eomponents should further be chosen so that they can be removed from the skin and underwear at least with the aid oE a detergent.
For a cosmetic preparation it has proven to be advantageous that the active ingredients or colorants are eommimlted with liquid or low-melting waxes or wax esters to give pastes which then may be dispersed in the castable composition without difficulties. The proportion of said components in general is between 1 and 20% by weight, and preferably from 5 to lOQ~ by weight, based on the eastable eomposition.
Glycerol monodioleate and fatty acid monoethanolamides such as stearic acid monoethanolamide have proven to be particularly suitable as further components of said phase since they provide a

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good adhesion on the p:igments to the skin. They are employed in amounts of from 0.1 to 10% by welght, and preferably from O.i to 5% by weight, of the castable composition. However, basically any fat or wax which is suitable to serve other eosmetic or medical purpose may be used for the powder preparation according to the invention.
There may be employed fats and liquid fats, waxes and such similar substances of natural and/or synthetic origin. This group ineludes not only the actual fats, i.e., the triglycerides of the higher fatty acids, but also the various liquid to solid waxes, the various fatty acid esters, the fatty aleohols, the esters and especially the polyvalent alcohols, the polyethylene glycols and their derivatives, the paraffin oils, vaselines and paraffins, silicone oils etc.: substanees which under certain conditions and especially in suitable eoneentrations all have the property of having a skin-caring aetion, like the actual fats that are liquid or solid at room temperature, and also giving at least that the skin, after applieation of such substanees, is greased, without leaving behind on the skin a film that beeomes visible. Sueh sub-stanees are suffieiently well-known and are already deseribed in great detain in generally available handbooks, for example, H.P.
Fiedler, Lexikon der Hilfsstoffe fur Pharmazie, Kosmetik und an-grenzende Gebiete (Lexikon of adjuvants for pharmaey, eosmeties and related fields), Ed. Cantor Verlag, Aulendorf~Wuerttemberg, 1971, page 14 to 16; H. Janistyn, Handbueh der Kosmetika und Riechstoffe, 1. Band: die kosmetischen Grundstoffe (handbook of eosmeties and perfumes. Volume 1: basie eosmetie substanees), Dr.

Alfred Huethig Verlag, lleidelberg, 1969, pages 37a to 399 and G.A. Nowak, die kosmetisehen Praeparate (eosmetie preparations), 1~3~
2nd edition, Verlag l Chem. Industrie, H. Ziolowsky, Augsbury, 1975 pages 192 to 198, 218 etc., 30~ to 312 and 424 to 449.
As the ac-tlve ingredients there may be used cosmetically effective or medically active substances such as deodorant sub-stances, light-protective agents, disinfectants or other sub-stances acting on or in the skin, more specifically those being sensitive to moisture. As the colorants there are preferably used colorant pigments, though basically it will also be possible to use water-soluble or fat-soluble dyes for certain applications.
The amounts of colorant pigments in extreme cases may be between 2 and 80% hy weight of the solid powder composition. Generally there are used amounts between 30 and 60~. In the case of very high proportions of colorant pigments attention is to be paid to that the particle sizes and shapes are not substantially dif-ferent from those of the filler(s).
As the evaporable non-toxic hydrophobic solvent there may basically ye used all such known solvents. Preferably those are used which have a evaporation number smaller of 80, i.e., especially aliphatic hydrocarbons as n-pentane, iso-pentane, n-hexane, n-heptane, isoparaffins, cycloalkanes, hydrocarbons sub-stituted by chlorine and/or fluorine, alcohols as ethanol, n-pro-panol, iso-propanol, n-butanol, ethyleneglycol, ether, ketones, esters as acetic acid ethyl ether and ethyleneglycol/monoacetate.
Silicone oils, more specifically the cyclic silicone oils having a or 5 silicone atoms have proven to be particularly useful. Of said solvents about 2 to 5~ by weight will remain in the solid preparation even after evaporation. In general amounts of from 20 to 60~ by weight of the composition are employed for the prepara-tion of the castable and fluid composi-tion. For the reasons of environment protection and ox lowering costs, the evaporated amounts of solvents are preferably recovered and reused. In the 3C3~

case of the silicone oils this may be very easily effected by passing the drying air, after cooling, through washing bottles filled with the solvents. The presence ox the remaining 2 to 5%
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solid p~der compo-iti~n is actu~ desired since the a~l~ition-ally impart a Good ~preadat~ y bv rubbing to the odor ~n-l render the po~](r spread on the skin Gore resistant to tran~ira-tion and rain.
Cyclic silicone oils such as polydimethylcyclosilo~ane may be conveniently processed at a temperature between 45C and 85C.
As further conventional additives, for example, antioxidants, preservatives and perfumes may be added to the solid powder compositions according to the invention. In as far as perfumes will escape from the composition in the step of evaporation of the solvent, they must be added in a respectively increased amount.
In carrying out the process according to the invention, the individual components are mixed and homogenized at a temperature in excess of 40C, preferably at a temperature between 75C and 90C, in a heatable kettle. The thus obtained fluid composition is cast into the desired molds preferably by using a casting machine comprising an automatically operating portioning system.
In the case that the casting step is to occur at a later time, it is possible to store the composition in closed containers at room temperature and to again convert into a melt prior to further processing.
When casting the castable composition into the molds, atten-tion is to be paid to that the casting composition is not cooled to below 45C while it flows in. Therefore, the molds are to be pre-heated if required, for example by using warm dry air.
The powder compositions according to the invention do not tend to shrink, neither upon being cooled nor upon evaporation of the solvent. Thus, they readily adhere to the casting molds.
However, in order to ensure a particularly strong adhesion, it is ~3~ 5 possible to roughen the rim and ~,ottoln surfaces of lie mold ,r provide them with a teYture.
The filled molds, once the liquid mass has cooled and soli-'-ified (below 40~C), are prefera}~ly stored in drying chambers operated with circulated air at 50C to 60C, whereby the predom-inant part of the excessive solvent is evaporated. The excessive solvent may be recovered in a simple way from the circulating air and re-used. If silicone oil is used, then, for example, subse-quent washing columns filled with silicone oil will be sufficient therefor.
The drying step is completed as soon as the powder prepa-rations have become sufficiently solidified, while, however, the powder on the suxface is still removable and spreadable as softly as silk and very thinly by means of an applicator or the dry 'inger tip. It is preferred that from 2 to 3% of the solvent, however a maximum of 5% of the solvent, are left in the solid preparation. More particularly, in the case of silicone oil this will result in an improved spreadability by rubbing and increased resistance to transpiration and rain of the colorant powder spread on the skin.
If required, the solid preparations in the molds may be visually checked for possible casting defects. However, the reject rate is surprisingly low. If desired, the surface is subsequently texturized or marked by means of a gentle pneumat-ically operated stamp under a pressure of about 5 bar.
The molds may be labelled and coded after having been filled, unless this has been done prior to the filling step.
Typical solid powder preparations according to the invention and processes for preparing same are illustrated by way of the following examples.

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x mple I
A fluid composition for pre[)aring a solid odor reparation ha the composition as follows Oleyl erucate 7.2~ by weiyht Stearic acid monoethanolamide 1.00 by weight Giycervl oleate 2.00 by weight Methyl paraben 0.20 by weight Propvl paraben 0.10 % by weight Butylhydroxytoluene (antioxidant) 0.10 % by weight Nylon-12 powder 12.00 % by weight Cyclomethicone * 48.70 % by weight Methylchloroisithiazolinone + methylisothiazolinone 0.20 % by weight Pigments and pearl pigments 28.50 % by weight 100.00 % by weigh-t The Nylon-12 powder consists of mostly spherical and ellipsoidal particles having a bulk density of from 0.20 to 0.35 g/cm3 and a density of from 1.02 to 1.03 g/cm3. The particle size distribution is as follows:
Proportion of particles larger than 40 ~mless than 0.5 %
40 to 30 ~mless than 6.0 %
30 to 20 ~mless than 10.0 %
20 to 10 ~mmore than 40.0 %
10 to 5 ~mmore than 30.0 %.
In conslderation of the standard deviation of 3.51 em there results an average par-ticle size of the powder of 12.1 em. The powder is hydrophobic and takes up a maximum l moisture from the air.

Part of the wax and fat is used for stirring the pigments such as to give a homogeneous dye paste. The remaining portion is * octamethylcyclotetrasiloxane a ? n I.
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charged into a double-wall,~d ve,sel clipped with a stirror and dispergc.tor, The antio~;idant Lend the presertlatives are further charged into thy vessel, and the contents is heated and melted at 85C. Then the dye pastes comprising the pigmen-ts and part of the way and fat phases are added with stirring to give a homogeneous produçt. The temperature is maintained at 80C to 85C. Now the silicone oil having been left at room temperature together with the preservative methylchloroisithiazolinone + methyliso-thiazolinone which is sensitive towards elevated temperature are added and the mixture is stirred until it is homogeneous. Then the Nylon powder is added as a powder with stirring, followed by the addition of the dry pearl pigment. In the homogenization procedure the temperature will be allowed to drop to 75C. With proper handling it is not necessary to deaerate the casting composition. In the case that air inclusions due to incautious operation are detectable, these ma be removed by applying a slightly reduced pressure of a ~n~ of 0.5 bar. Now,- the casting composition is complete and is allowed to slow into a casting machine comprising an automatically operating portioning system to fill powder boxes at a temperature of 75C. depending on size and dimensions of the boxes it may be required to pre-heat same at about 30C by means of dry hot air so that in the course of inflow of the casting composition the temperature will not drop to below 45C. After about 1 to 2 minutes and cooling to a temperature below 45C the cast mass will solidify to give a semi-solid cream. The filled molds are then put in layers into a drying cabinet at 60C through which a strong stream of air is circulated and kept therein for about 15 hoursO
The permanently flowing air stream entrains the slowly evaporat-ing volatile silicone oil. It is removed from the circulating air by means of subsequently located washing columns kept cool and filled with the same silicone oil and may be re-used.

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The drying step is come tl?d as soft a the (ler cornpcJ~
tion has been com21etely solicliEie~l, wile however, the po:/dcr on the surface is still removable and spre~ldable as softly as silt an verv thinly by means of an applicator or the dry finqer tip. The content of silicone oil amounts to a ma:{imum of 5~, pre-ferablv to from 2 to 3%.
The surface of the cast molds may be marked by means of a stamp with a pressure of about S bar or be decorated with a texture pattern.
When 0.20 to 0.50~ by weight of a perfume are to be added, the amount of silicone oil is correspondingly reduced.
Examples 2 and 3 In a manner analogous to that described in Example 1, the components listed hereafter were processed together to give solid powder preparations.
Example 2 Example 3 % by % by weightweight Oleyl erucate 7.20 7.20 Stearic acid monoethanolamide1.00 1.00 Glyceryl oleate 2.00 2.00 Methyl paraben 0.20 0.20 Propyl paraben 0.10 OolO
Butylhydroxytoluene antioxidant) 0.10 0.10 Tricalcium phosphate 12.00 Polyethylene -.-- 15.00 Cyclomethicone 56.2053.20 Methylchloroisithiazolinone -I methvlisothiazolinone 0.20 0.20 Pigments and pearl pigments21.00 21.00 100.00100.00 l 5r~ a n The avl?ra~e particle dia~leter of the tricalcium phosphate was 6 to em. The aver.l~e diamf?ter ol the polyr~th~lene powdcr was 6 em. when perfume was added, the portion of siliconf? oil was correspondingly reduced.
The obtained products also had a good appearance and were removable and spreadable as softly as silk and very thinly by means of an applicator or the dry finger tip. No bloating and crumbling-away was observed as in the recipes according Canadian Patent No. 1,125,659.

Claims (12)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A solid powder preparation for medical or cosmetic purposes containing a) at least one filler, said filler being a non-hygroscopic flowable organic or inorganic solid having a particle size of from 5 to 50 µm in diameter, b) at least one fatty or waxy component, c) at least one cosmetically effective or medically active ingredient, and d) at least one evaporable, non-toxic, hydrophobic solvent.

2. The preparation according to claim 1, wherein the fill-er is a spherical or ellipsoidal powder of polyethylene, polypropylene, polyvinylpyrrolidone, polyamide or a hydrophobic inorganic salt.

3. The preparation according to claim 2, wherein at least 70% of the filler has a particle size of from 10 to 25 µm.

4. The preparation according to claim 1, wherein the active ingredient is moisture sensitive.

5. The preparation according to claim 1 containing a colorant as a cosmetically effective ingredient.

6. A process for preparing a solid powder preparation for medical or cosmetic purposes containing a) at least one filler, said filler comprising a non-hygroscopic flowable organic or inorganic solid having a particle size of from 5 to 50 µm in diameter b) at least one fatty or waxy component, c) at least one cosmetically effective or medically active ingredient, and d) at least one evaporable, non-toxic, hydrophobic solvent which comprises mixing said components with an excess of the solvent at a temperature in excess of 40°C to give a fluid composition, casting the fluid composition into a mold, and evaporating excess solvent.

7. The process according to claim 6, wherein the solvent is a silicone oil.

8. The process according to claim 7, wherein the evaporated excess of the solvent is trapped and re-used.

9. The process according to claim 6 wherein the composition in the mold is shaped by the application of a pressure less than 10 bar.

10. A solid powder preparation for medical or cosmetic purposes comprising:
a) a non-hygroscopic flowable organic or inorganic solid filler having a particle size of from 5 to 50 µm in diameter, b) a fatty or waxy component, c) a cosmetically effective or medically active ingredient, and d) an evaporable, non-toxic, hydrophobic solvent, said preparation having no tendency to shrink, a smooth and uniform surface, and a pleasant soft powder spreading with no bloating and crumbling away at the surfaces of the preparation.

11. The solid powder preparation of claim 10, compris-ing:
a) a polyamide having a particle size of from 5 to 50 µm in diameter, b) stearic acid monoethanolamide, c) methylparaben, and d) octamethylcyclotetrasiloxane.

12. The solid powder preparation of claim 10 or 11, comprising -10 to 80% by weight of component a), 0.1 to 10% by weight of component b), 30 to 60% by weight of component c), and to 5% by weight of component d).