MXPA99006612A - Light screening composition containing a polysiloxane type uv-b screening agent and a benzimidazol type uv-b screening agent - Google Patents

Abstract

The invention relates to a cosmetic light screening composition containing in an aqueous phase about 0.5 to 10 wt%of 2-phenylbenzimidazol-sulphonic acid or a salt thereof and at least one fatty phase, comprising about 1 to 30 wt%of a linear or cyclic polysiloxane compound of the general formula Ia or Ib, wherein Xsignifies R or A;Asignifies a group of the formula IIa, IIb or IIc;Rsignifies hydrogen, C1-6 alkyl or phenyl;R1 and R2each independently signify hydrogen, hydroxy, C1-6-alkyl or C1-6-alkoxy;R3signifies C1-6-alkyl;R4signifies hydrogen or C1-6-alkyl;R5 and R6each independently signify hydrogen or C1-6-alkyl;rhas a value of from 0 to 250;shas a value of from 0 to 20;r +shas a value of at least 3;thas a value of from 0 to10;vhas a value of from 0 to10;and v+thas a value of at least 3;nhas a value from 1 to 6;with the proviso that in the case that s is 0 at least one X is A.

Description

LIGHT FILTRATION COMPOSITIONS CONTAINING AN AGENT OF ULTRAVIOLET RAY FILTRATION OF POLYISYLOXANIC TYPE AND A ULTRAVIOLET RAY FILTRATION AGENT OF BENZIMIDAZOLE TYPE Description of the invention: The invention relates to photostable cosmetic light filtration compositions for the protection of the human epidermis against ultraviolet rays of wavelength between 280 and 320 nm (UV-B). In particular, the invention relates to cosmetic light filtering compositions containing a lipophilic polysiloxane type UV-B filtering agent and a hydrophilic benzimidazole type UV-B filtration agent. In European Patent Publication PE-0813857 a sunscreen composition is described having a synergistic UV protection activity comprising an aqueous phase; a first oil phase; a second oil phase; an emollient for the emulsion of the oil-in-water type and another emollient for the water-in-oil emulsion; a hydrophilic 5 UV-A filter such as, for example, benzophenone derivatives or a hydrophilic UV-B filter, such as, for example, benzimidazole derivatives and a lipophilic UV-A filter, such as, for example, 4-tert-butyl-4 '-methoxydibenzoylmethane (PARSOL 1789R) or a lipophilic UV-B filter such as, for example octocrylene (UVINUL N-539R) 0 or an organosiloxane filter as described in WO 93/04665 or an organosiloxane filter of the benzotriazole type as described in WO94 / 06404, said sunscreen composition is characterized in that the first and second oil phases are incompatible. The European publication quoted above only mentions in general that the combined filter substances have a synergistic ultraviolet protection activity without giving any guidance to select a specific filter combination to achieve REF .: 30611 a specific synergistic effect. In addition, the organosiloxanes as described in WO 93/04665 or WO94 / 06404 do not specifically refer to organosiloxanes containing a benzoomalonate-type orthoro residue. It has now been found that a sunscreen composition containing a polysiloxane with a chromophore residue of the benzomalonate type as a lipophilic UV-B filtering agent and a hydrophilic benzimidazole UV-B filtering agent provides protection indices. synergistically improved. More specifically, the present invention relates to a cosmetic light filtration composition containing in an aqueous phase about 0.5 to 10% by weight of 2-phenylbenzimidazole-sulfonic acid or a respective salt, and at least one fatty phase , which comprises about 1 to 30% by weight of a linear or cyclic polysiloxane compound of the general formula Ia or Ib, where X means R or A; A means a group of the formula lia, I Ib or lie; II b R means hydrogen, C] __ 6 alkyl or phenyl; 15 R! and R ^ each independently, hydrogen, hydroxyl, C] __ 6 alkyl or C] __ g alkoxy; R3 signifies alkyl of C] __ g; > R 4 is hydrogen or Cj__g alkyl; R5 and R6 each independently denote hydrogen or Ci-g alkyl; r has a value from 0 to 250; s has a value from 0 to 20; r + s has a value of at least 3; t has a value from 0 to 10; 25 v has a value from 0 to 10; and v + t has a value of at least 3; n has a value of 1 to 6; with the proviso that in case s is 0 at least one X is A.

The term "Cj__5 alkyl" refers to groups such as methyl, ethyl, propyl, isopropyl, butyl, secondary butyl, isobutyl, pentyl and neopentyl. The term "C alkoxy] __ g" refers to the corresponding alkoxy groups. The residues R are preferably methyl. The residues R1 and R ^ are preferably hydrogen, methoxy or ethoxy, more preferably hydrogen, or one of R ^ and R2 is hydrogen and the other is methyl, methoxy or ethoxy. The radicals R ^ are preferably methyl or ethyl, more preferably ethyl. . Preferably R4 is hydrogen or methyl; R ^ and R ^ are hydrogen and n is 1. Appropriate salts of 2-phenylbenzimidazole-sulfonic acid are alkali salts, such as sodium or potassium salts, ammonium salts, morpholine salts, salts of primary, secondary and tertiary amines such as salts of monoethanolamine, diethanolamine salts and the like. The polysiloxane compounds having a group A of the general formula Ia and IIb and their preparation are described in European Patent PE 0538431 Bl. These polysiloxane compounds are preferred. The polysiloxane compounds having a group A of the general formula lie and their preparation are described in European Patent EP 0358584 Bl. In the linear polysiloxane compounds according to the formula, the chromophore comprising the residue A can be connected to the end groups of the polysiloxane (X = A) or they can be distributed statistically. Preferred are linear polysiloxane compounds in which the chromophore comprising residue A is statistically distributed. These preferred polysiloxane compounds have at least one unit that comprises the chromophore residue (s = 1), preferably s has a value of about 2 to about 10, more preferably a statistical average of about 4. The number of r of the other silicon units present in the polysiloxane compounds is preferably about 5 to about 150, more preferably a statistical average of about 60. The polysiloxane compounds wherein 20% or less, preferably less than 10 %, of the total siloxane units are units that carry a chromophore residue are preferred with respect to the cosmetic properties. The ratio of polysiloxane units having a chromophore residue A of the formula Ia to those having a chromophore residue A of the formula IIb is not critical. This ratio can be from about 1: 1 to about 19: 1, preferably about 2: 1 to about 9: 1, more preferably about 4: 1. The concentration of the polysiloxane compound in the cosmetic light filtering composition is preferably 2 to 20% by weight, more preferably about 5% by weight. The concentration of 2-phenylbenzimidazole sulfonic acid or a respective salt is preferably about 0.5 to 5% by weight, more preferably about 1 to 2% by weight.

The ratio of 2-phenylbenzimidazole sulfonic acid or a respective salt to the polysiloxane compound as defined above is not critical. For example, the ratio is from about 1: 1 to about 1:20, preferably about 1: 5. Thus, a preferred cosmetic light filtering composition contains in an aqueous phase about 0.5 to 5% by weight of 2-phenylbenzimidazole-sulfonic acid or a respective salt, and at least one fatty phase, comprising about 2 to 20% by weight of a linear polysiloxane compound of the general formula la, wherein X means methyl; A means a group of the formula lia or Ilb; R means methyl; R1 and R ^ mean hydrogen, methoxy or ethoxy, or one of R! and R2 is hydrogen and the other is methyl, methoxy or ethoxy; R3 means methyl or ethyl; R4 means hydrogen or methyl; R ^ and R6 means hydrogen; r is around 5 to about 150; s is around 2 to about 10; n has a value of 1. A most preferred cosmetic light filtering composition contains in an aqueous phase about 1 to 2% by weight of 2-phenylbenzimidazole-sulfonic acid or a respective salt and at least one fatty phase, comprising about 5% by weight of a linear polysiloxane compound of the general formula la, wherein X means methyl; A means a group of the formula lia or Ilb; R means methyl; R1 and R2 signifies hydrogen, R3 signifies ethyl; R4 means hydrogen; R5 and R ^ means hydrogen; r is a statistical mean of around 4; s is a statistical mean of around 60; n has a value of 1. The polysiloxane compounds Ia or Ib wherein A is a radical of the formula lia or IIb can be prepared as described in EP 0538431 Bl by silylation of the corresponding benzal-malonates according to the following reaction scheme : wherein R1, R2 and R3 are as defined above. Silylation of the 4- (2-propynyloxy) phenyl methylene diethyl ester can be carried out using known methods for the addition of hydrogen atoms bonded to silica to groups containing aliphatic unsaturation. These reactions are generally catalyzed by a metal of the platinum group or a complex of such a metal. Examples of catalysts that can be used are platinum or carbon, chloroplatinic acid, acetyl acetonate of platinum, complexes of platinum compounds with unsaturated compounds, for example olefins and divinyl disiloxanes, complexes of rhodium and palladium compounds and complexes of platinum compounds supported on inorganic substrates. The addition reaction can be carried out under reduced, atmospheric or increased pressure. A solvent, for example toluene or xylene, may be used in the reaction mixture although the presence of the solvent is not essential. It is also preferred to carry out the reaction at elevated reaction temperatures, for example from about 50 ° C to 150 ° C. The production of the new light filtering compositions comprises incorporating a polysiloxane compound as defined above and 2-phenyl-benzimidazole-sulfonic acid or a respective salt optionally in combination with other UV- "A and / or UV- filters. B known, on a cosmetic basis that is usual for light filtering agents Suitable UV B filters, that is, substances having absorption maxima between about 290 and 320 nm, are, for example, the following organic compounds, which they belong to the broadest classes of substance: p-aminobenzoic acid derivatives such as ethyl-, propyl-, butyl-, and isobutyl p-aminobenzoate and the like; Acrylates such as 2-ethylhexyl 2-cyano-3,3-diphenylacrylate ( octocrylene), ethyl-2-cyano-3, 3-diphenylacrylate and the like; aniline derivatives such as methyl aniline methosulfate and the like; anthranilic acid derivatives such as menthyl anthranilate and the like; benzophenone derivatives such as benzophenone-3 , benzophenone-4 and the like. Derivatives of camphor such as methyl benzylidene camphor (PARSOL 5000), 3-benzylidene camphor, camphor benzalkonium methosulfate, polyacrylamidomethyl benzylidene camphor, sulfa benzylidene camphor, sulfomethyl benzylidene camphor, terephthalide dicanfor sulphonic acid and the like; Cinnamate derivatives such as octyl methoxycinnamate (PARSOL MCX) or ethoxyethyl methoxycinnamate and the like, as well as cinnamic acid derivatives bonded to siloxanes; Gallic acid such as digaloyl trioleate and the like; Salicylate derivatives such as isopropylbenzyl salicylate, benzyl salicylate, butyl salicylate, octyl salicylate (Neo Heliopan OS), isooctyl salicylate or homomenthyl salicylate (homosalate, Heliopan) and the like; Triazole derivatives such as hydroxyphenylbenzotriazole, 2,2'-methylene-bis- (6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) -phenol (TINOSORB M) and the like; triazone derivatives thereof such as octyl triazone (Uvinul T-150), dioctyl butamido triazone (Uvasorb HEB) and the like Pigments such as microparticulate TiO2, ZnO and the like The term "microparticulate" refers to a particle size of about 5 nm to about 200 nm, particularly from about 15 nm to about 100 nm The TiO2 particles can also be coated with metal oxides such as, for example, aluminum or zirconium oxides or medianthe organic coatings such as, for example, polyols, methicone, stearate of aluminum, alkyl silane These coatings are well known in the art The formulation may additionally contain UV-A filters such as Dibenzoylmethane derivatives such as 4-tert.butyl-4'-methoxy-dibenzoyl-methane and the like; of triazine as described in Patent publications en European PE 0693483 Al, PE 0704437 A2, PE 0704444 Al and PE 0780382 Al, for example 2,2'- [6- (4-methoxyphenyl) -1,4,5-triazin-2,4-diyl] bis [ 5- [2-ethylhexyl) oxy] -; which is under the TINOSORB S brand of Ciba Specialty Chemicals Holding Switzerland. As usual cosmetic bases for light filtering compositions within the scope of the present invention, any conventional preparation corresponding to the cosmetic requirements may be used, for example creams, lotions, emulsions, ointments, gels, sprays solutions, bars and milks; see also, Sunscreens, Development, Evaluation and Regulatory Aspects, ed. N.Y. Lowe, N.A. Shaath, Marcel Dekker, Inc. New York and Basel, 1990. The following examples explain the invention in more detail.

EXAMPLE 1 Preparation of. { (4- [2-propynyloxy) phenyl] methylene} -diethyl ester propandioic as described in EP 0538431 Bl. To a stirred suspension of 4-hydroxybenzyl aldehyde (425.8 g) and K2CO3 (807.6 g) in acetone (2.96 ml) at reflux temperature of about 60 ° C under a nitrogen atmosphere was added dropwise. 3-bromo-propin (502.4 g) over a period of two hours. The reaction was heated to reflux for more than 3 hours. After cooling to room temperature, the reaction mixture was filtered, the excess K2CO3 was separated and washed several times with acetone. The filtrate was washed with saturated aqueous NaHCOß solution and NaCl. The aqueous phase was extracted with diethyl ether. The combined organic extracts were dried over Na 2 SO 4, filtered and concentrated to a volume of 1 1. The solution was kept in the refrigerator overnight. The crystals were filtered and washed with cold diethyl ether. The filtrate was kept in the refrigerator and some more crystals were developed and separated. This procedure was repeated 3 times resulting in 1.385 g of 4- (2-propy-nyloxy) benzaldehyde in 83% yield. The material was analyzed by gas chromatography and showed to be 99.9% pure. The resulting compound (449.5 g) was added in small amounts to a stirred solution of diethylmalonate (448.5 g), piperidine (23.84 g), toluene (1400 ml) and acetic acid (59 g) to about 50 ° C. The acetic acid had been added in three equal portions after 1, 1,5 and 2 hours respectively. The reaction mixture was heated to reflux. After four hours the mixture was allowed to cool to room temperature and was washed with saturated aqueous solution of NaHCO 3 and NaCl, dried with Na 2 SO 4, filtered and concentrated to give 853.4 g of a dark brown oily product. Diethyl ether (458 ml) and n-hexane (358 ml) were added and the solution was kept in the refrigerator overnight. The solution was filtered, yielding 564.8 g of light brown crystals (yield "of 67%) with. a melting point of 4.5 to 48 ° C. Recrystallization from ethanol and n-hexane gave 543 g of the peygra compound as clear brown crystals. The material was analyzed by gas chromatography and proved to be 99.9% pure. EXAMPLE 2 Preparation of an organosiloxane compound of the general formula wherein R means methyl, s is 0, r is 20, X is A and A is a benzalmalonate residue of the formula lya and IIb where R ^ - and R2 are hydrogen, R3 is ethyl and R4, R ^ and R6 are hydrogen, n is 1 as described in EP 053 431 Bl. 5 g of ether were dissolved. { [4- (2-propynyl-oxy) phenyl] methylene} -diethyl in 20 g of toluene and heated under nitrogen to about 80 ° C. Then, after addition of a complex of platinum-divinyl-tetramethyl-disiloxane, 13.2 g of a hydrosiloxane with a degree of polymerization of SiH groups of 20 and 10 mpc (3.62% SiH) was added dropwise. , giving 10-4 mol of Pt per mol of SiH of the hydrosiloxane. The mixture was heated to reflux and maintained until all the SiH had disappeared from the infrared spectroscopic analysis. Then let it cool down to room temperature. The toluene was then evaporated to give after washing 16.5 g of a slightly brown polymer with the average structure A- [(CH3) 2SiO] 20-A 'wherein A is a radical of the formula IIa] _ and Ubi EXAMPLE 3 Preparation of an organosiloxane compound having the general formula wherein R means methyl, r is 59, s is 4, X is methyl and A is a benzalmalonate residue of the formula lia and IIb wherein R ^ and R2 they are hydrogen, R3 is ethyl, R4, R5 and R6 are hydrogen as described in European publication PE 0709080 Al. 13.28 g of ester were dissolved. { [4- (2-propynyl-oxy) phenyl] methylene} -dietyl in 73 g of toluene and heated under nitrogen to about 70 ° C. It was then added to "drops, after adding also a complex of platinum-divinyl-tetramethyl-disiloxane, 44 g of a hydrosiloxane with a degree of polymerization of SiH groups of 65 and 6 mpc (2.36% SiH), giving 10-4 mol of Pt per mole of SiH of the hydrosiloxane, the mixture was heated to reflux and kept until all the SiH had disappeared from the infrared spectroscopic analysis, then it was allowed to cool to room temperature, then the toluene was evaporated to leave after washing 52 g of a viscous brown polymer with the average structure (CH ^^ SiO- [(CH3) 2SiO] 59- [(CH3) ASiO] 4-Si (013) 3, wherein A has the formula IIa ] _ and IIb_ The ratio of compounds having a residue I1 to compounds having a residue IIb is about 4: 1.

EXAMPLE 4 Suitable Cosmetic Light Filter Compositions A sunscreen oil / water solution comprising 5% by weight of a polysiloxane of the formula I according to Example 3 and 1% by weight of 2-phenylbenzimidazole-sulfonic acid was prepared with The following ingredients: Part% weight / weight ingredient Name CTFA A 2,5 Arlacel 60 Sorbitan stearate sold by ICI 17,5 Witconol APM PPG-3 myristyl ether sold by Witco 1, 0 Stearyl alcohol Stearyl alcohol 5, 0 Polysiloxane 5,0 Silica oil Dimethicone 200/100 B 1/0 PBSA Phenylbenzyl-1-azol sulfonic acid 1/8 10% NaOH Sodium hydroxide 2.5 Tween 60 Polysorbate 60 0.3 Keltrol Xanthan gum sold by Kelco UK 61.4 Water 2.0 Sepigel 305 Polyacrylamid & C13-14 sold by Seppic isoparafin + lauret-7 CTFA: Cosmetic, Toiletry and Fragrance Association. Part A: Added and melted in the reactor. Part B: rocking, neutralizing and heating on hot plate at 85 ° C. Part C: is added at 50 ° C.

EXAMPLE 5 Determination of the Sun Protection Factor The determination of the Sun Protection Factor was carried out in accordance with the COLIPA protocol (the European Cosmetic, Tolletry and Perfumery Association, Sun Protection Factor Test method, October 1994). An SU 2000 solar simulator with a lamp intensity in the range of 5.0 to 5.5 mW / cm2 was used. irradiation area 6 xl cm2; 25% dose progression. The following filter combinations have been formulated using the same cosmetic base as described in Example 4 to give a stable sunscreen lotion with identical distribution characteristics. An application dose of 2 mg / cm2 was used in accordance with the COLIPA protocol for measurements of SPF in vivo in humans, over an application area of 50 cm2. As a comparison, the following sunscreen compositions have been tested: A "solar" filter composition containing a polysiloxane compound according to Example 3 and a second known lipophilic UV-B filter, ie 2-ethylhexyl-p-methoxy; cinnamate (OMC) (available under the trademark PARSOL MCX) A sunscreen composition containing a polysiloxane compound according to example 3 and a second known hydrophilic UV-B filter, ie the diethanolamine salt of p-acid Methoxycinnamic (MC-DEA) (available under the brand name PARSOL Hydro).

The results are shown in the following Table.

UV filter FPS in vivo FPS expected synergy % by weight P3 4.7 2% by weight PBSA 6.8 5% by p. P3 + l% in p.PBSA 8.1 5,8 40 ^ comparative 10% in weight P3 4.7 2% in weight OMC 5.3 5% in p.P3 + l% in p.OMC, 5.8 5.0 16í 10% by weight P3 4.7 2% by weight MC-DEA 4.2 5% in p.P3 + l% in p.MC-DEA 4.8 4/5 7% P3: Polysiloxane according to example 3. PBSA: 2-phenylbenzimidazole-sulphonic acid OMC: 2-ethylhexyl-p-methoxycinnamate MC-DEA: p-methoxycinnamic acid diethanolamine salt. FPS in vivo: Average value of determination on 5 volunteers.

Expected SPF: Value calculated by adding in vivo FPS value from 10% by weight of P3 (4.7) to SPF value in vivo of 2% by weight of the corresponding value for the other filters, divided by 2. Synergy% deviation in vivo of SPF of the expected SPF (calculated). The combination of PBSA and the polysiloxane according to the invention shows a disproportionate increase in FPS.

Usually the FPS of the filter combinations is very close to the value calculated from the provision of the simple filters, so a synergistic effect is shown in this combination.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.

Claims (11)

2. Having described the invention as above, the content of the following claims is claimed as property: 1. Composition of cosmetic light filtrate in an aqueous phase of about 0.5 to 10% by weight of 2-phenylbenzyl-1-azole-sulfonic acid or a respective salt and at least vna fat phase, < "-t« * • »! = * it = rH rpjp mtxtaifle alred? cfcr of 1 to 3Q £ by weight ds a linear or cyclic polysiloxane compound of the general formula Ia or Ib, where X means R or A; A means a group of the formula lia, IIb or líe;
3. II b R stands for hydrogen, C? _g alkyl or phenyl; R1 and R2 each independently denote hydrogen, hydroxyl, Cg alkyl or Cj__g alkoxy; R3 is Cg alkyl; R4 means hydrogen or C? _g alkyl; R5 and R6 each independently denote hydrogen or C? _g alkyl; r has a value from 0 to 250; s has a value from 0 to 20; r + s has a value of at least 3; t has a value from 0 to 10; v has a value from 0 to 10; and v + t has a value of at least 3; n has a value of 1 to 6; with the proviso that in the case that s is 0 at least one X is A. or IIb. 3.- Composition of cosmetic light filtering, of
4. Quifijiiüdad cm the Ticarp? 1 or 2, cis-esterization because the organosiloxane compounds having chromophoric residue of the formula Ia to organosiloxane compounds having a chromophore residue of the formula IIb are from about 1: 1 to about 19: 1, preferably from about 2: 1 to about 9: 1, more preferably about 4: 1. 4.- Cosmetic light filtration composition, according to any of claims 1 to 3, characterized in that R is methyl.
5. 5. - Cosmetic light filtration composition, according to any of claims 1 to 4, characterized in that R - * - and R 2 are hydrogen, rretoxOo or ethoxy, or? Xr > of R - * - and R2 is hydrogen and the other is methyl, methoxy or ethoxy.
6. 6. - Cosmetic light filtration composition, according to any of claims 1 to 5, characterized in that R is methyl or ethyl
7. 7.- Cosmetic light filtering composition, according to any of claims 1 to 6, characterized perqué R is hydrogenTD or methyl, R and R sin hirógepo and n is 1.
8. 8.- Cosmetic light filtration composition, according to any of claims 1 to 7, csa ^ eferizacb perqué ccrrtdene in a fse acucea alr rfedpr of 0.5 to 3 £ by weight of 2-phenylbenzimidazole-sulphonic acid or a respective salt, and at least one fatty phase, comprising about 2 to 20% by weight of a linear polysiloxane compound of the formula general, wherein X means methyl, A represents a group of the formula lia or Ilb, R represents methyl, R1 and R2 signifies hydrogen, methoxy or ethoxy, or one of R and R2 is hydrogen and the other is methyl, methoxy or ethoxy; R3 means methyl or ethyl; R4 means hydrogen or methyl; R5 and R6 signify hydrogen; r is around 5 to about 150; s is around 2 to about 10; n has a value of 1.
9. 9.- Composition of cosmetic light filtering, of iiformity with reiviridication. 8, characterized in that about 1 to 2% by weight of 2-phenylbenzimidazole-sulphonic acid or a respective salt and at least one fatty phase, comprising about 5% by weight of a poly-siloxane compound, is present in three aqueous phases; linear of the general formula la, wherein R1 and R2 signify hydrogen; R3 signifies ethyl; R4 means hydrogen; r is a statistical mean of around 4; s is a statistical average of about 60.
10. 10.- Cosmetic light filtering composition, according to any of claims 1 to 9, characterized in that it dictates crmicosicide in addition to WA filter and / or common UV-B filters. .
11. 11. The use of a cosmetic light filter composition according to any of claims 1 to 10 as an absorber for ultraviolet light. SUMMARY OF THE INVENTION The invention relates to a cosmetic light filtering composition in an aqueous phase of about 0.5 to 10% by weight of 2-phenylbenzimidazole-sulfonic acid or a respective salt and at least one fatty phase, comprising about 1 to 30% by weight of a linear or cyclic polysiloxane compound of the general formula Ia or Ib, where X means R or A; A means a group of the formula lia, IIb or lie; II b 5 R means hydrogen, C? _g alkyl or phenyl; R! and R2 signify each, independently, hydrogen, hydroxyl, C? _g alkyl or C? _g alkoxy; R3 is Cg alkyl; R4 means hydrogen or Cg alkyl; ilO R ^ and R ^ mean each, independently, hydrogen or C? _g alkyl; r has a value from 0 to 250; s has a value from 0 to 20; r + s has a value of at least 3; 15 t has a value from 0 to 10; v has a value from 0 to 10; and v + t has a value of at least 3; n has a value of 1 to 6; with the proviso that in case s is 0 at least 20 * an X is A.