MXPA96003589A

MXPA96003589A - Method to improve the absorption of the ultraviolet radiation of a composite

Info

Publication number: MXPA96003589A
Application number: MXPA/A/1996/003589A
Authority: MX
Inventors: Michael Fasano David; Elwood Jones Charles; Vogel Martin; Gonzalez Aviles Rafael
Original assignee: Rohm And Haas Company
Priority date: 1995-08-24
Filing date: 1996-08-22
Publication date: 1997-06-01

Abstract

The present invention provides a method for improving the absorption of ultraviolet (UV) radiation of a composition that contains an agent that absorbs this UV radiation, adding approximately 0.1 to 50 weight percent latex particles, based on the total weight of the non-volatile products. The latex particles contain a gap and have a particle size of approximately 100 nm to 380

Description

METHOD TO IMPROVE THE ABSORPTION OF THE ULTRAVIOLET RADIATION OF A COMPOSITION FIELD OF THE INVENTION The invention relates to a method for improving the absorption of ultraviolet radiation, in which hollow latex particles are added to a composition containing at least one agent that absorbs this ultraviolet radiation. BACKGROUND OF THE INVENTION Six percent of the solar energy that reaches the earth's surface is in the form of ultraviolet (UV) radiation, with a wavelength of 290 to 400 nanometers (nm). This radiation has two components: (1) 5.5% of UVA that has a wavelength of 320 to 400 nm and (2) 0.5% of UVB, which has a wavelength of 290-320 nm. While the portion of UV radiation from solar energy is relatively small, it induces about 99% of all the side effects of sunlight. UVB radiation, for example, is responsible for the production of sunburn, aging and cancer of the skin. UVA radiation, for example, causes direct tanning and erythema (abnormal reddish color) and contributes to the aging of the skin. By avoiding exposure to sunlight, people can avoid the serious effects caused by UV radiation. However, many people, due to the nature of their work, can not avoid exposure to the sun. In addition, others voluntarily expose their skin to the sun for their tan, sometimes excessively. Therefore, protection against the damaging effects of the sun is important. Protection from these detrimental effects of exposure to UV radiation is available in the form of topically applied formulations, which contain at least one physical blocker, or at least one chemical absorbent, or its combinations. Physical blockers include active ingredients, such as red petrolatum, titanium dioxide and zinc oxide. Chemical absorbers include active ingredients, such as para-a-benzoic acid (more commonly known as PABA), which is generally transparent when applied and acts by absorbing UV radiation and offering selective protection against certain UV wavebands, depending of the absorption spectrum of the particular active ingredient incorporated in the formulation. The effectiveness of a formulation that protects against the sun is generally assessed by how well it protects the skin in terms of a Sun Protection Factor (SPF), which is defined as the ratio of the amount of energy required to produce an erythema. minimum on the skin protected against the sun, to the amount of energy required to produce the same level of erythema on unprotected skin. A number of chemical absorbers and physical blockers, also referred to herein as "UV absorbing agents", typically used in sun-protecting formulations, have adverse toxicological effects. Therefore, it is convenient to reduce the level of agents that absorb UV radiation, present in a sunscreen formulation, without reducing the level of protection. An attempt to reduce the level of agents that absorb UV radiation in a sunscreen formulation is disclosed in U.A. Patent No. 4,804,531 to Grollier, hereinafter referred to as "Grollier". Glollier discloses adding to the protective cosmetic composition, an aqueous dispersion of polymer particles, insoluble in water, where these polymer particles comprise: a) an ionic polymer, which forms a core capable of being swollen and (b) a polymer that it forms an envelope, which encapsulates, at least partially, the core. Water-insoluble polymer particles will be developed to form a film, and have a glass transition temperature of the shell below 50 ° C and an average particle size, before swelling, of 70 nanometers (nm) up to 4,500 nm. Grollier states that, when polymer particles, insoluble in water, are added to a cosmetic sun protection composition, at a level of 0.1 to 10 percent by weight, based on the total weight of the protective cosmetic composition, the absorption of UV radiation is increased by this protective cosmetic composition. Improving the teachings of Grollier, we have unexpectedly found that hollow latex particles, which have certain particle sizes, increase the absorbance of UV radiation in a composition containing one or more agents that absorb UV radiation: BRIEF DESCRIPTION OF THE INVENTION We have discovered a method for improving the UV absorption of a composition, this method comprises: adding to said composition about 0.1 to 50 weight percent latex particles, based on the total weight of non-volatile products, wherein this composition comprises at least one agent that absorbs UV radiation and where the latex particles contain are hollow and have a size of about 100 to 380 nm.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: Figure 1 is a spectrum of the absorbance of UV radiation of a wavelength of 280 to 440 nm, for compositions containing no additives, solid latex particles and hollow latex particles they are at a coating level of 0.775 microliters per square centimeter (μl / cm2). The active ingredients in the compositions are 2-ethylhexyl para-methoxycinnamate and menthyl anthraneyate. The additives are incorporated at a level of 5% by weight, based on the total weight of non-volatile products.

Figure 2 is an absorbance spectrum of UV radiation of a wavelength of 280 to 440 nm, for compositions containing no additives and the hollow latex particles are at a coating level of 1.55 μl / cm2. The active ingredients in the compositions are 2-ethylhexyl para-methoxycinnamate and menthyl anthranilate. The additives are incorporated at a level of 5% by weight, based on the total weight of the non-volatile products. Figure 3 is a spectrum of UV absorbance for a wavelength of 280 to 440 nm, for compositions containing no additives and the solid latex particles and hollow latex particles are at a coating level of 3.10 μl / cm2. The active ingredients in the compositions are 2-ethylhexyl para-methoxycinnamate and menthyl anthranilate. The additives are incorporated at a level of 5% by weight, based on the total weight of non-volatile products. Figure 4 is a spectrum of UV radiation absorbance of a wavelength of 280 to 440 nm, for compositions containing no additives and the solid latex particles and hollow latex particles are at a coating level of 6.20 μl / cm2. The active ingredients in the compositions are 2-ethylhexyl para-methoxycinnamate and menthyl anthranilate. The additives are incorporated at a level of 5% by weight, based on the total weight of non-volatile products.

Figure 5 is a graph showing for 6 the compositions that absorb UV radiation, the ratio of the Sun Protection Factor (SPF) for the compositions (Y axis) versus the particle size, in nm, of the particles of hollow latexes contained in the compositions (X axis). These hollow latex particles (as solids) are incorporated into the compositions at a level of 10 percent by weight, based on the total weight of the non-volatile products. In addition to the hollow latex particles, the compositions also contain phenylbenzyl idazole sulfonic acid, an agent that absorbs UV radiation.

DETAILED DESCRIPTION OF THE INVENTION The method of the invention improves the absorption of UV radiation of a composition containing at least one agent that absorbs this UV radiation. The method of the present invention includes incorporation of about 0.1 to 50 weight percent, and preferably about 1 to 20 weight percent, based on the total weight of non-volatile, hollow latex particles, to a composition that contains at least one agent that absorbs this ultraviolet radiation. As used herein, the term "UV radiation" includes both UVA and UVB radiation.The latex particles, useful in the method of this invention, have a size of about 100 to 380 nanometers (nm), preferably about 150 at 375 nm, more preferably from about 190 to about 350 nm, and especially preferred from about 251 to 325 nm, as measured by the photon correlation spectrometer, Brookhaven BI-90.

For a given particle size, it is convenient to produce latex particles with a maximum void fraction, such as current process techniques, and to allow the integrity of the particles. Preferably, the latex particles contain voids with a fraction of these voids of about 0.1 to 50% and more preferably 5 to 50%. The void fractions are determined by comparing the volume occupied by the latex particles, after they have been compacted from a dispersion diluted in a centrifugal apparatus, to the volume of non-hollow particles of the same composition. The hollow latex particles, useful in the method of this invention, are formed of multi-stage particles, comprising at least one core polymer and at least one shell polymer. The core polymer and the shell polymer can be obtained in a single polymerization step or in a sequence of these polymerization steps. The hollow latex particles are prepared by conventional polymerization techniques, such as sequence emulsion polymerization, which includes the processes disclosed in U.S. Patents Nos. 4,427,836, 4,469,825, 4,594,363, 4,677,003, 4,920,160 and 4,970,241, the descriptions of which are incorporated herein by reference. incorporate here as a reference. The hollow latex particles can also be prepared, for example, by the polymerization techniques disclosed in European Patent Application 0,267,726, European Patent Application 0,331,421, U.A. Patent A., 4,910,229 or U.A. Patent A., 5,157,084.

The monomers used in the emulsion polymerization of the shell polymer of the hollow latex particles preferably comprise one or more ethylenically unsaturated, nonionic monomers. Optionally, one or more monoethylenically unsaturated monomers containing at least one carboxylic acid group can be polymerized in the shell. The monomers comprising the shell are selected to provide a glass transition temperature (Tg) in at least one shell, which is high enough to support the gap within the latex particle. Preferably, the Tg of at least one cover is greater than 502C, more preferably greater than 602C and especially preferred greater than 70ac, as measured by differential scanning calorimetry.

The monomers used in the emulsion polymerization of the core polymer of the hollow latex particles, preferably comprise one or more monoethylenically unsaturated monomers, containing at least one carboxylic acid group. Preferably, this core comprises at least 5 weight percent of the monoethylenically unsaturated monomers, containing at least one carboxylic acid, based on the total weight of the core onomer. The core polymer can be obtained, for example, by the emulsion homopolymerization of the monoethylenically unsaturated monomer, which contains at least one carboxylic acid group or by the copolymerization of two or more monoethylenically unsaturated monomers, containing at least one acid group carboxylic Preferably, the monoethylenically unsaturated monomer, which contains at least one carboxylic acid group, is copolymerized with one or more non-ionic, ethylenically unsaturated monomers (ie, having no ionizable groups).

The core polymer or shell polymer may optionally contain about 0.1 to 20 weight percent, preferably 0.1 to 3 weight percent, based on the total weight of the core monomer, of the polyethylenically unsaturated monomer, such as ethylene glycol di (meth) acrylate, allyl (et) acrylate, 1,3-butanediol di (meth) acrylate, di-ethylene glycol di (meth) acrylate, tri (meth) acrylate trimethylolpropane or divinylbenzene. Alternatively, the core polymer or shell polymer may optionally contain about 0.1 to 60 weight percent, based on the total weight of the core monomer, butadiene.

Suitable monoethylenically unsaturated monomers containing at least one carboxylic acid group include, for example, acrylic acid and methacrylic acid, acryloxypropionic acid, (meth) acryloxy-propionic acid, itaconic acid, aconitic acid, acid or maleic anhydride, fumaric acid, crotonic acid, monomethyl maleate, monomethyl fumarate and mono-methyl itaconate. Acrylic acid and methacrylic acid are preferred.

Suitable ethylenically unsaturated, nonionic monomers include, for example, styrene, vinyltoluene, ethylene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, (meth) acrylamide, alkyl (C1-C20) alkenyl esters (C3-C20) of (meth) acrylic acid, such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) acrylate benzyl, lauryl (meth) acrylate, oleyl (meth) acrylate, palyltyl (meth) acrylate and stearyl (meth) acrylate. As used herein, the term "(meth) acrylic" is intended to serve as the generic term encompassing both acrylic and methacrylic.

The hollow of the latex particles is preferably produced by swelling the core with a swelling agent, which contains one or more volatile components. This swelling agent infiltrates the cover to inflate the core. The volatile components of the swelling agent can then be removed by drying the latex particles, which causes the formation of a gap inside these latex particles. Preferably, the swelling agent is an aqueous base. Aqueous bases useful for swelling the core include, for example, ammonia, ammonium hydroxide, alkali metal hydroxides, such as sodium hydroxide, or a volatile amine, such as trimethylamine or triethylamine. The hollow latex particles can be added to the composition with the swelling agent present in the core. When the latex particles are added to the composition with the swelling agent present in the core, the volatile components of the swelling agent will be removed by drying the composition. The hollow latex particles can also be added to the composition after removing the volatile components of the swelling agent. In addition to the hollow latex particles, the composition improved by the method of the present invention contains at least one agent that absorbs UV radiation. The agent that absorbs UV radiation can be incorporated into the composition at a level to produce a desired sun protection factor. For example, the agent that absorbs UV radiation can be added to the composition at a level generally of 0.1 to 15 weight percent, approximately, based on the total weight of the non-volatile products in the composition. The agents that absorb UV radiation, used in the method of this invention, are conventional materials. Suitable agents that absorb UV radiation include, for example, oxybenzone, dioxybenzone, sulisobenzone, menthyl anthranilate, para-aminobenzoic acid, amyl para-dimethylaminobenzoic acid, octyl para-dimethylaminobenzoate, 4-bis- (hydroxypropyl) -para ethyl aminobenzoate, polyethylene glycol para-aminobenzoate (PEG-25), ethyl 4-bis- (hydroxypropyl) -aminobenzoate, diethanolamine para-methoxy-cinnamate, 2-ethoxy para-methoxycinnamate -ethyl, ethylhexyl para-methoxycinnamate, octyl para-methoxycinnamate, octyl para-methoxycinnamate, isoamyl para-methoxycinnamate, 2-cyano-3, 3-diphenyl-2-ethylhexyl acrylate, 2-ethylhexyl salicylate, salicylate of homomenthyl, glyceryl aminobenzoate, triethanolamine salicylate, digaloyl trioleate, lawsone with di-hydroxyacetone, 2-phenylbenzimidazole-5-sulfonic acid, benzylidine-camphor, avobenzone, titanium dioxide and zinc oxide. The composition improved by the method of this invention may also include other conventional ingredients, used in compositions that absorb UV radiation. For example, if the composition is used as a sunscreen, it may additionally include water, film-forming materials, emulsifiers, emollients, waterproofing agents, oils, stabilizers, thickeners, preservatives, perfumes, dyes, insecticides or humectants, or their combinations. If the composition is used as a cosmetic, it may additionally include, for example, water, film-forming materials, emulsifiers, softeners, emollients, oils, stabilizers, thickeners, preservatives, perfumes, colorants or pigments, or combinations thereof. . The composition improved by the method of this invention can be used in any application where the protection of UV radiation is useful. For example, the improved composition can be used on human skin and head, such as, for example, in personal care products, which include cosmetics, sunscreens and hair care products. In addition, the method of this invention is also useful in improving the absorption of UV radiation and protection for coatings in living plants, plastics, wood, for example in the form of a clear varnish. The method of this invention can be used to improve the absorption of UV radiation in clear or pigmented formulations. The method is particularly useful if a clear formulation, such as a sunscreen formulation, is desired., because the addition of hollow latex particles, having a particle size of less than about 300 nm, does not contribute significantly to whiteness. The method of this invention makes it possible for formulators to increase the absorbance of UV radiation of a given formulation or to reduce the level of the UV absorbing agent present in the formulation, while maintaining a given absorbance of UV radiation.

The compositions improved by the method of this invention can be applied to the skin at coating volumes, for example, from about 0.5 to 4 microliters per square centimeter.

EXAMPLES Some embodiments of the invention will now be described in detail in the following examples. The following abbreviations are used in the Examples: MMA% by weight of methyl methacrylate BMA% by weight of butyl methacrylate MAA% by weight of methacrylic acid Sty% by weight of styrene ALMA% by weight of allyl methacrylate pep parts by weight For Examples 1 and 2, the hollow latex particles, having particle sizes ranging from 150 to 548 nm, were added to the formulations containing at least one agent that absorbs UV radiation, to determine the Effectiveness of hollow latex particles in improving the absorption of UV radiation. The hollow latex particles, in Examples 1 and 2, were prepared in a manner similar to the method described in the U.S. Patent No. 4,427,836. The hollow latex particles tested in Examples 1 and 2 have the following composition, unless stated otherwise: Core: 1 pep (60 MMA / 40 MAA) Coated I: 16 pep (10 BMA / 86 MMA) / 4 MAA) Deck II: 12 pep (99.5 Sty / 0.5 ALMA) Deck III: 9 pep, (100 Sty). To swell the core, excess ammonia (based on total acid equivalents in the monomer) was added to the hot dispersion (80-852C), between the polymerization of cover II and cover III, to inflate the core. The hollow latex particles had a final particle size and the hollow fraction, as shown in Table I.

The particle size of the hollow latex particles was measured using a Brookhaven BI-90 photon correlation spectrometer.

The percentage of the hollow fraction of the latex particles was measured by the centrifugation method, described in the Detailed Description of the Invention.

TABLE I: Empty Latex Particles, for Examples 1 and 2 Example 1; A composition containing hollow latex particles, useful in the present invention, was evaluated in its effectiveness in absorbing UV radiation, with various thicknesses of the coating, to simulate different levels of protection of the sun on human skin. The composition containing the hollow latex particles was also compared to a composition containing the solid latex particles, which has a particle size similar to the hollow latex particles. The following procedure was used: Three compositions were prepared for measurements of UV absorbance: Comparative Composition A: does not contain hollow latex particles or solid particles as additives (without additives) Comparative Composition B: contains, as an additive, solid polystyrene particles, which have a size of about 179 nm Composition 1: Contains Polymer B as an additive (hollow latex particles, see Table I) Compositions were prepared by adding the additive at a level of 5% solids, based on total weight, to the Hawaiian Tan Tanic Tanning Lotion Lotion with a Sun Protection Factor of 4, manufactured by Tanning Research Laboratories. The materials that absorb UV radiation in said lotion were 2-ethylhexyl para-methoxycinnamate and menthyl anthranilate.

The prepared compositions were coated at a level of 0.775, 1.55, 3.1 and 5.2 microliters per square centimeter (μl / cm2) on a Transpore® belt, from Minnesota Mining and Manufacturing Company, to simulate different levels of sun protection on human skin . The absorbance spectrum of UV radiation of a wavelength of 280 to 440 nm for each sample was measured using an Optronics Laboratories 752 Spectroradiometer radiometer-spectrum. The spectra at coating levels of 0.775, 1.55, 3.1 and 6.2 microliters per square centimeter (μl / cm2) are shown in Figures 1, 2, 3 and 4, respectively.

Composition 1, which contains both at least one UV absorbing agent and the hollow latex particles, exhibited increased absorbance of UV radiation at each coating level, over the wavelengths tested (280-440 nm), compared to the composition containing only one agent that absorbs UV radiation (Comparative Composition A). Composition 1 also exhibited increased absorbance of UV radiation at each level of coating, compared to Comparative Composition B, which contains an agent that absorbs UV radiation and solid latex particles, of a size similar to that of Polymer B. The results demonstrate that the presence of a gap in the latex particles improves the absorbance of UV radiation of a composition containing a UV absorbance agent.

Example 2; The hollow latex particles, useful in the present invention, were evaluated for their effectiveness in absorbing UV radiation with various particle sizes in a composition containing at least one agent that absorbs UV radiation. The procedure used was as follows: A test composition, containing the hollow latex particles, to be tested, was prepared according to the composition shown in Table II (Test Composition).

TABLE II; Test Composition Ingredients Weight Parts Deionized water 75.10 Aculyn® 22 2.25 99% Triethanolamine 0.61 Neo Heliopan Hydro (30%) 12.00 Kathon® CG 0.04 Hollow Latex Particles 10.00 (as solids) A control composition was also prepared, referred to herein as hereinafter referred to as the "Control", according to the composition shown in Table II, except that hollow latex particles were not added. Aculyn® 22, supplied by Rohm and Haas Company, was added to the composition to provide thickening. Kathon® CG, also supplied by Rohm and Haas Company, was added to the test composition as a biocide. The Neo Heliopan Hydro, an agent that absorbs UV radiation, is supplied by Haarmann & Reimer and is chemically phenylbenzimidazole-sulfonic acid.

The ability of the test composition to absorb UV radiation was evaluated by measuring the sun protection factor (SPF) of the test composition. The SPF was measured using the SPF 290 Analyzer and the SPF Operating Software, supplied by The Optometrics Group, located in Ayer, Massachusetts. The SPF 290 Analyzer measured the absorbance of UV radiation from a sample over the wavelengths of UV radiation and calculated the SPF value based on this UV absorbance spectrum. The following procedure was used to measure the SPF.

For each test composition, which includes the Control, a Transpore® tape 10.16 cm long by 7.62 cm wide, from Minnesota Mining and Manufacturing Company, was cut and placed in the SPF 290 Analyzer. Using a 1.0 cc graduated syringe, 0.1 cc of the composition to be tested was uniformly applied to the test area of about 50 square centimeters. The composition was dried on the tape for 20 minutes.

While drying the composition to be tested, a tape that does not contain the composition was measured in the absorbance of background UV radiation, using the analyzer. This SPF 290 Analyzer device subtracts the background absorbance of the tape to calculate the SPF for the test composition.

After drying, the test composition was measured in the SPF, using the SPF 290 Analyzer in 6 different locations within the test area of the tape. These 6 measurements were averaged. The above procedure for measuring the SPF was repeated for the same test composition, to obtain 6 additional measurements of the SPF. The 12 measurements of the SPF were averaged to obtain the final SPF.

Table III shows the final SPF values for the compositions that were tested, according to the previous procedure. Table III shows for each test composition, the latex particles that were tested, the particle size of the hollow latex particles, the percentage of the emptying fraction of the latex particles and the final value of the SPF. A higher SPF value for a test composition indicates that a greater amount of UV radiation is absorbed, compared to another test composition having a lower SPF value. The data in Table III is also shown graphically in Figure 5. Table III and Figure 5 show that the UV absorbance of the test composition, which contains at least one agent that absorbs UV radiation, unexpectedly increases , when the latex particles have a particle size of about 100 to 380 nm. The increase is especially larger with a particle size varying from approximately 190 to 350 nm.

TABLE III; Pineapple SPP Values for Test Compositions Containing Latex Vacuum Particles Comparative * Polymers C, D, E, F and G were compositionally similar to Polymer A

Claims

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following is claimed as property:
CLAIMS 1. A method for improving the absorption of ultraviolet radiation of a composition, which comprises adding to this composition about 0.1 to 50 weight percent latex particles, based on the total weight of the non-volatile products, wherein the composition includes at least one agent that absorbs UV radiation, and where the latex particles are hollow and have a particle size of about 100 nm to 380 nm. 2. The method according to claim 1, wherein. the latex particles are added to the composition to provide an approximate level of 1.0 to 20 weight percent of the latex particles in the composition.
3. The method according to claim 1, wherein. The size of the latex particles is approximately 150 to 375 nm.
4. The method according to claim 1, wherein. The size of the latex particles is approximately 190 to 350 nm.
5. The method, according to claim 1, wherein. the latex particles have a gap fraction of approximately 0.1 to 50%.
6. The method, according to claim 1, wherein. the latex particles have a void fraction of approximately 5 l 50%.
7. The method, according to claim 1, wherein. the agent that absorbs UV radiation is a chemical, selected from the group consisting of oxybenzone, dioxybenzone, sulisobenzone, menthyl anthranilate, para-aminobenzoic acid, amyl para-dimethylaminobenzoic acid, octyl para-dimethylaminobenzoate, -bis- (hydroxypropyl) -para ethyl aminobenzoate, polyethylene glycol para-aminobenzoate (PEG-25), ethyl 4-bis- (hydroxypropyl) -aminobenzoate, diethanolamine para-methoxycinnamate, para-methoxycinnamate 2- ethoxyethyl, ethylhexyl para-methoxycinnamate, octyl para-methoxycinnamate, octyl para-methoxycinnamate, isoamyl para-methoxycinnamate, 2-cyano-3,3-diphenyl-2-ethylhexyl acrylate, 2-ethylhexyl salicylate, homomenthyl salicylate, glyceryl aminobenzoate, triethanolamine salicylate, digaloyl trioleate, lawsone with dihydroxyacetone, 2-phenylbenzimidazole-5-sulfonic acid, benzylidine-camphor, avobenzone, titanium dioxide and zinc oxide.