BACK INJECTION MOLDING PROCESS

Abstract: A process is provided for forming a molded cosmetic product by back injection molding, in which a molding is formed from a slurry of a powder and a non-volatile solvent.

Description: BACK INJECTION MOLDING PROCESS This application claims priority of U.S. Provisional Patent Application Serial No. 60/035,212, filed January 10, 1997. BACKGROUND OF THE INVENTION I. FIELD OF THE INVENTION The present invention relates generally to a back injection molding process. More particularly, the invention relates to a back injection molding process that does not use volatile organic compounds (VOCs). Specifically, the process does not use volatile hydrocarbons or alcohols as solvents for forming the slurry from which the molded item is formed. Most particularly, the invention is directed to a method of molding cosmetic compositions into suitable shapes using a back injection molding process in which a solvent, preferably water, is used to form a slurry with powdered cosmetic ingredients. The slurry is then molded in a pan to the desired shape using the back injection molding process. II. DESCRIPTION OF THE PRIOR ART Back injection molding processes and apparatus for conducting same are known in the art. Specifically, back injection molding machinery is available in the United States from the Nanyo Company of Japan. In such a back injection molding process, powdered components are mixed and pulverized to form a powdered mixture, which is then combined with a solvent to form a slurry. The slurry is fed into the back injection molding apparatus, which injects the slurry into a mold of the desired shape, to form a molded cosmetic product. Current process technology uses volatile hydrocarbons (i.e. alcohols, kerosene, etc.) to "wet" out the mixture of powdered components and form the slurry. These materials are classified as volatile organic compounds (VOCs) . VOCs are strictly regulated with regard to the release of volatile vapors into the atmosphere. Due to these regulations, areas in which organic solvents are used must be segregated from the remainder of the manufacturing facility and special procedures must be observed for the disposal of waste products containing the volatile materials. Since additional handling costs are needed to comply with these regulations, the cost of the process as a whole is increased. In addition, when using organic solvents, it is desired that no solvent remains in the finished product. It would, therefore, be advantageous to provide a substitute solvent for use in conjunction with a back injection molding process that does not contain any VOCs. The present process contains no VOCs. Therefore, it provides a simplified processing environment or area, namely there is no need for special air handling equipment and techniques. SUMMARY OF THE INVENTION Against the foregoing background, it is a primary object of the present invention to provide a back injection molding process for forming a molded body from a slurry of powdered components in a solvent, preferably water. It is another object of the present invention to provide a molded cosmetic composition formed using a back injection molding process with a solvent that simulates the aesthetic properties achieved using the prior art volatile organic compounds, but does not contain a volatile organic compound. To accomplish the forgoing objects and advantages, the present invention, in brief summary, is a back injection molding process in which a slurry to be molded is formed by combining powdered components and a solvent. The solvent is preferably either a solution of water and a surface active agent, or an emulsion of (1) at least one oil, ester or silicone and (2) water. A preferred use of the back injection molding process is to form molded cosmetic products such as a blush, eyeshadow, foundation, lipstick, eyebrow liner, mascara, or the like, that simulate the aesthetic properties of cosmetics formed using the prior art volatile organic compounds, but does not contain a volatile organic compound, and can be produced using currently available back injection molding machinery. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram of a first embodiment of the inventive process, in which a solution of water and surface active agent is used as a solvent; and Fig. 2 is a block diagram of a second embodiment of the invention in which the solvent is an oil in water emulsion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention provides a novel back injection molding process in which one or more powdered components are combined with a solvent that is not a volatile organic compound to form a slurry. Such a solvent is non-volatile for purposes of this invention. Preferably, such a solvent is or includes water. It is preferred that the water used in the present invention be demineralized, having no ionic character. The formed slurry is injected into a pan or other container (collectively referred to as a pan herein) and dried to form a molded body in the pan. In the present process, the solvent used to form the slurry contains no volatile organic compounds (VOCs), thereby alleviating environmental and consumer safety concerns. In addition, the costs associated with the process are lowered. As stated above, while it is envisioned that this process can be used to form a variety of molded compositions, it is particularly useful in the formation of molded cosmetic compositions, such as a blush, eyeshadow, foundation, lipstick, eyebrow liner, mascara, or the like. To this end, a solvent must be selected that will provide a molded cosmetic composition that will simulate the aesthetic properties of cosmetics formed with the previously used volatile solvents . Equipment for conducting back injection molding processes is known. Such machinery is available, for example, from the Nanyo Company of Japan. The process of the invention can be conducted on such presently available equipment without the need for modification. The back injection molding (BIM) process can best be understood with reference to Fig. 1. In one embodiment of the inventive back injection molding process, powdered component ingredients are, in a first stage, blended and pulverized 1. Pearls are then added and the powdered components are blended a second time 2. A liquid binder is then sprayed 3 onto the mixed powder. The mixed powder with binder is then blended and pulverized 4 again. In a second stage, the mixed powder with binder is combined with a solvent 5, and mixed, for example, in a planetary mixer, to form a slurry. In this instance, the solvent is water and a surfactant. In a third stage, the slurry is injected 6 via pressure using the back injection molding machine into a pan while optionally applying vacuum and then drying to remove excess solvent. The application of vacuum can be used to draw excess solvent from the slurry. Drying is preferably achieved by ambient temperature air drying, but other methods of drying, such as heating, can also be used. In addition, any combination of the foregoing solvent removal methods can be used. The pan is formed with holes in the bottom thereof through which the slurry composition can be injected. An item, such as a molded body in the pan, is formed. Fig. 2 illustrates a second embodiment of the invention, with similar steps bearing the same reference numbers as in Fig. 1. In a first stage of the process shown in Fig. 2, powdered components are blended and pulverized 1. Pearls are then added, and the powdered components are blended a second time 2. In a second stage, the mixed powder is combined with a solvent 5, and mixed, for example, in a planetary mixer, to form a slurry. In this case, the solvent is an oil in water emulsion. In a third stage, the slurry is injected 6 via pressure using the back injection molding machine into a pan, while optionally applying vacuum and then drying to remove excess solvent, to form an item, such as a molded body in the pan. As a second alternative, the pan is formed without a bottom. Nonetheless, the slurry is injected through the open bottom. The pan is removed from the machine, and the molded body, while in the pan, is allowed to dry. In all embodiments, the molded body in the pan is placed in a suitable container, such as a cosmetic compact . As a solvent for preparing the slurry, the present process employs either (1) a solution of a surface active agent (surfactant) in water, or (2) an oil in water emulsion comprised of water and at least one ester, oil and/or silicone. It is known that anionic, nonionic and amphoteric surfactants or surface active agents (or mixtures thereof) can be used. The surfactant can be mixed with the water, or incorporated onto the powdered components prior to wetting. The suitable anionic surfactants include, but are not limited to, sodium lauryl sarcosinate and sodium laureth sulfate, or mixtures thereof. The suitable nonionic surfactants include, but are not limited to, dimethicone copolyol, Poloxamer 184 and mixtures thereof; while the suitable amphoteric surfactants include, but are not limited to, lauramidopropyl betaine, cocamidopropyl hydroxysultaine and mixtures thereof. It is believed that cationic surfactants may be used. However, it is believed that cationic surfactants are not as suitable due to the pigments used in cosmetics. The powdered components of the cosmetic material are those generally known in the art. They can include, for example, (a) fillers, such as talc, mica, nylon powder, and sericite; (b) preservatives; and (c) colorants, such as pigments and/or pearls. In the case of the process using a water/surface active agent solvent, the powdered components can be precontacted with a liquid binder including at least one oil, ester and/or silicone. The powdered components are thoroughly mixed and pulverized before introduction of the solvent. When the solvent is formed of a surface active agent in water, this solvent comprises: about 25% to about 99.9% water, and an amount of surface active agent of about 0.10% to 25%. Due to color requirements, the mixed powdered components can be about 10% to about 90%, preferably about 35% to about 65%, and most preferably about 50%, of the total slurry weight with the remainder being solvent. The mixed powdered components will comprise about 20% to about 70% fillers, about 0.5% to about 1.0% preservatives, zero to about 50% colorants, and about zero to about 20% of a liquid binder, based on the total weight of the mixed powder component. When the solvent is an oil in water emulsion, the solvent comprises: about 25% to about 90% water, about 0.01% to about 25% of emulsifiers and about 0.01% to about 25% of ester/oil/silicone. Due to color requirements, the mixed powdered components can be about 10% to about 90%, preferably about 35% to about 65%, and most preferably about 50%, of the total slurry weight with the remainder being solvent. The mixed powdered components will comprise: about 30% to about 99% fillers, about 0.5% to about 1.0% preservatives, and zero to about 80% colorants, based on the total weight of the mixed powder component. As shown in the following Examples, test data demonstrate the properties of cosmetics formed using the process described above. Comparative examples are designated throughout as "(comp.)" or "control". Examples The following slurries were injected under various molding conditions into a standard Back Injection Molding Pan: Ingredient Ex. 1 Ex. 2 Ex. 3 Ex. 4 (comp. ) Back Injection B#l 200 200 200 200 Demineralized Water 196 196 196 POE(26M)-POP(29M) Polymer (CTFA: Poloxamer 184) 4 POE(26M)-Glycerol (CTFA: Glycereth-26) 4 POE(20M) Sorbitan Monolaurate (CTFA: Polysorbate 20) 4 Isopropyl Alcohol 200 Back Injection B#l includes: Ingredient Weight Percent Talc and mica 50.240 Other additives 44.713 Pigments 4.521 Preservatives 0.526 100.000 The slurries of Examples 1 through 4 were molded under the following conditions: Injection Time Pressure Paper Advance (seconds) (kg/cm 2 ) (seconds] 1.5, 1.75, 2.5, 2.75, 3.75, 4.5 3.5 1.0 4.5 4.5 0.5 The slurries of Examples 1, 2 and 3 displayed a good consistency, while the slurry of Example 4 (the comparative example, using a standard volatile solvent; was thin. When molded into products, each slurry provided an aesthetically acceptable cosmetic that was powdery and sheer. The slurries of Examples 1 and 2 provided a similar color. The color of the product formed with the slurry of Example 3 was bleached out. The product formed with the slurry of comparative Example 4 felt best. The slurry of Example 1 provided a better product compared to the slurries of Examples 2 and 3. Processing conditions of 3.75 or 4.5 second injection time, in combination with 3.5 kg/cm 2 pressure and 1 second paper advance, were preferred and provided the best results. In determining optimal processing parameters, it was found that the paper was prone to breakage; an advance of 1.0 second provided the best result. With the slurries of Examples 2 and 3 the paper had a tendency to stick. Therefore, it is important to optimize the water level and use a strong and absorbent paper. Slurries were prepared and back injected under various conditions into conventional back injection molding pans, and into a pan having a frame structure. Ingredient Ex. 5 Ex. 6 (comp, Back Injection B#Q 400 400 Demineralized water 392 POE(26M)-POP(29M) Polymer (CTFA: Poloxamer 184) 8 Isopropyl Alcohol 400 Back Injection B#Q includes: Ingredient Weight Percent Talc and mica 67.990 Other additives 15.039 Pigments 3.190 Preservatives 0.701 Pearls 6.000 Esters and oils 7.080 100.000 The slurries of Examples 5 and 6 were molded under the following conditions: Injection Time Pressure Paper Advance (seconds) (kg/cm 2 ) (seconds) 4.5 4.5 0.5 3.5, 5.5 4.0 0.5 Both slurries were back injection molded into the pans without problems; no paper ripping or sticking. With a 3.5 second injection time, some lifting was noted with the slurry of Example 5. The product of the slurry of Example 5 had more of a yellow color, and was more pearly compared to the product formed with the slurry of Example 6 (the comparative product, using a conventional volatile solvent) . Slurries of powder (lOg powder B#A23) and a combination of water (9.8g) and surface active agent (0.2g) were prepared and poured into a pan to form a product that was evaluated for initial properties and after 4 and 24 hours. Ex. # CTFA Name Type surface active agent Dimethicone Copolyol Non-Ionic Sodium Lauroyl Sarcosinate Anionic Sodium Laureth Sulfate Anionic 10 Lauramidopropyl Betaine Amphoteric 11 Cocamidopropyl Hydroxysultaine Amphoteric 12 Poloxamer 184 Non-Ionic B#A23 includes Ingredient Weight Percent Talc and mica 66.227 Other additives 15.041 Pigments 5.990 Preservatives 0.694 Pearls 6.000 Esters and oils 7.080 100.000 Ex.. - Slurry Flowability Observations 7 OK/thick scooped in (1 color looks same (2 look OK (3 look OK, color good 8 OK/thick can tap down (1 color looks same (2 look OK (3 look OK, color red/brown 9 OK/slightly can tap down (1 color appears reddish thick (2 look OK (3 look OK, color good 10 OK/thick can tap down (1 slight reddish color (2 look OK (3 reddish color 11 OK can tap down (1 reddish color (2 look OK (3 slight reddish color 12 OK/very No/Placed in (1 colors look same thick pan with (2 spatula (3 (1) initial; (2) after 4 hours at 120°F; (3) after 24 hours All the surfactants were soluble in water. To further determine the aesthetic qualities of cosmetics formed in accordance with the invention, slurries were formed as follows and injected into molding pans under various conditions: Ingredient 13 14 15 16 17 18 19 (comp. ) Powder Phase 100 100 100 100 100 100 100 (B#A24) Dimethylsiloxane Glycol 150* Sodium Lauroyl Sarcosinate 140* Sodium Laureth Sulfate 135* Lauramidopropyl Betaine 125* Cocamidopropyl Hydroxysultaine 125* Poloxamer 184 165' Isopropyl Alcohol 90* thin OK OK very good good thin All weights for Examples 13 through 19 are in grams; *Weights given represent solutions of 2% of the listed weight of the specified surface active agent and 98% (the remainder) demineralized water Powder Phase B#A24 includes: Ingredient Weight Percent Talc and mica 65.227 Other additives 16.041 Pigments 5.990 Preservatives 0.694 Pearls 4.968 Esters and oils 7.080 100.000 The slurries of Examples 13 through 19 were molded under the following conditions: Injection Time Pressure Paper Advance (seconds) (MPa) (seconds) 4.5 0.5 1.0 Aesthetic Evaluation Example Drop Payoff Glazing Feel Color (vs. No. (2 samp. ) control) 13 OK OK OK OK slightly reddish 14 OK OK OK OK much redder 15 OK OK OK OK comparable 16 OK OK OK OK comparable 17 OK OK OK OK comparable 18 OK OK OK OK comparable 19 OK OK OK OK control Stability All samples were similar to the comparative example 19 — the control — after one month storage at 110°F and at 40°F. There was no cracking, discoloration or lifting from pan. Samples for Examples 13, 14 and 15 filled well at the listed conditions. Ten samples were filled, one had a hole through the cake (blow through) . Ten samples were prepared for each of Examples 16, 17 and 18. Each filled well under the noted conditions. Some samples initially stuck to the paper, then fell off. The samples were acceptable. Five samples were prepared for Example 19. All filled well under the noted conditions. The invention having been thus described with particular reference to the preferred forms thereof, it will be obvious that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims .

Claims: What is claimed is: 1. A process for forming a powder into a molded product comprising the steps of: mixing said powder with a non-volatile solvent to form a slurry; back-injecting said slurry into a back injection mold; and removing at least a portion of said non-volatile solvent from said slurry to solidify said molded product . 2. The process of claim 1, wherein said nonvolatile solvent comprises water and a surface active agent . 3. The process of claim 1, wherein said nonvolatile solvent comprises an emulsion of water, and at least one substance selected from the group consisting of oils, esters and silicones. 4. The process of claim 1, wherein said molded product is a cosmetic. 5. The process of claim 4, wherein said cosmetic is selected from the group consisting of blush, eyeshadow, foundation, lipstick, eyebrow liner and mascara. 6. The process of claim 1, wherein said powder contains at least one component selected from the group consisting of filler, preservative and colorant. 7. The process of claim 6, wherein said filler is selected from the group consisting of talc, mica, nylon powder, sericite and mixtures thereof. 8. The process of claim 6, wherein said colorant is selected from the group consisting of pigments, pearls and mixtures thereof. 9. The process of claim 2, wherein said powder includes a liquid binder before it is mixed with said non-volatile solvent. 10. The process of claim 2, wherein said surface active agent is selected from the group consisting of anionic surfactant, non-ionic surfactant, amphoteric surfactant and mixtures thereof. 11. The process of claim 10, wherein said anionic surfactant is selected from the group consisting of sodium lauryl sarcosinate, sodium laureth sulfate and mixtures thereof. 12. The process of claim 10, wherein said nonionic surfactant is selected from the group consisting of dimethicone copolyol, Poloxamer 184 and mixtures thereof. 13. The process of claim 10, wherein said amphoteric surfactant is selected from the group consisting of lauramidopropyl betaine, cocamidopropyl hydroxysultaine and mixtures thereof. 14. The process of claim 2, wherein said solvent comprises about 25 wt . % to about 99.9 wt . % water and about 0.1 wt . % to about 25 wt . % of said surface active agent, and said slurry comprises about 10 wt . % to 90 wt.% of said powder components. 15. The process of claim 14, wherein said powder comprises, based on a total weight of said powder, about 20 wt.% to about 70 wt.% fillers, about 0.5 wt.% to about 1.0 wt.% preservatives, about 0 wt.% to about 50 wt.% colorants and about 0 wt.% to about 20 wt.% of a liquid binder. 16. The process of claim 3, wherein said solvent comprises about 25 wt.% to about 90 wt.% water, about 0.01 wt.% to about 25 wt.% emulsifier, and about 0.01 wt.% to about 25 wt.% of said oil, said ester, said silicone or said mixture thereof, and wherein said slurry comprises about 10 wt.% to about 90 wt.% of said powder. 17. The process of claim 16, wherein said powder comprises, based on a total weight of said powder, about 30 wt.% to about 99 wt.% fillers, about 0.5 wt.% to about 1.0 wt.% preservatives, and about 0 wt.% to about 80 wt.% colorants. 18. The process of claim 2, wherein said powder is blended, pulverized, sprayed with a liquid binder and mixed and pulverized again, prior to mixing with said solvent. 19. The process of claim 3, wherein said powder is blended and pulverized, pearls are added and said powder is blended and pulverized again, prior to mixing with said solvents. 20. The process of claim 1, wherein said portion of said non-volatile solvent is removed from said slurry by means selected from the group consisting of ambient temperature air drying, heating, application of vacuum and a combination thereof. 21. The process of claim 20, wherein said slurry is injected into a pan through a bottom access hole, and wherein said non-volatile solvent is removed by applying a vacuum to said solvent through a filter paper provided over a top of said pan. 22. A molded cosmetic product formed by the process of claim 1.

Inventors: SEAGREN GLENN W, SEAGREN, GLENN, W.
Applicants: AVON PROD INC, AVON PRODUCTS, INC.
Application year: 1998
Main classification: A61K7
IPC codes: A61K8, A61Q1, B29C45