Patent Application
20050136080
Field of the Invention
The invention relates to cosmetic solid leads, and in particular to a cosmetic solid lead encased with plastic and having a lipophilic phase that is liquid at room temperature or ambient temperature. The lipophilic phase is intimately mixed with a base material which is solid at ambient temperature.
The liquid phases used are conventionally mineral oils, such as paraffin oil with high contents of unbranched chains and fatty acid esters, such as isopropyl tetradecanoate (isopropyl myristate). The solid phases often form waxes and fatty acid derivatives often form the solid phase. The liquid lipophilic phase, which is often present in large amounts, brings about lead consistency, which allows soft marking on the skin and imparts shine to the areas of skwherein have been made up.
The liquid lipophilic phase, particularly when it is present in large amounts, brings about a reduction in the thermal stability of the cosmetic lead. At elevated temperatures, for example upon storage of the lead in heated rooms, the lead has a tendency to lose oil, i.e., the liquid lipophilic phase that had been previously mixed homogeneously with the solid phase separates out, possibly resulting in the formation of drops on the lead tip which can lead to soilings and interfere with application. This can be remedied to a certain extent by using a lead matrix with increased retention capacity for the liquid lipophilic phase, i.e., for example for oils. Microcrystalline waxes in particular are suitable. The described effects are also counteracted by using lead casings which absorb at least some of the exuded liquid phase. Materials which can do this are those with a microporous structure, for example wood or plastic to which pore formers have been added during preparation. However, liquid can only be absorbed if there is an open-pored structure, i.e., if the micropores open into the inner surface of the lead casing and are joined together. The latter can reduce the impermeability of the casing, which is undesired due to a consequent evaporation of volatile lead constituents. The micropores further hinder the production of clearly transparent casings or make it impossible altogether. A further way of countering the described effect consists in adding fillers with an open-pored structure to the casing. However, such fillers have considerable effects on the optical appearance of the casing and also influence its chemical and mechanical properties.
It is accordingly an object of the invention to provide a solid cosmetic lead, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides for a cosmetic lead encased by plastic and having a high content of a lipophilic phase that is liquid at room temperature wherein loss of oil is avoided in an alternative way.
With the foregoing and other objects in view there is provided, in accordance with the invention, a cosmetic solid lead encased by plastic, comprising:
In other words, the objects of the invention are achieved with the basic concept according to which the lipophilic phase, which is present in a large amount, at least 25%, is formed completely or at least predominantly from a chemical substance which dissolves in the plastic of the casing. This is very generally associated with the advantage that a plastic can be used which has an adequate absorption capacity for the liquid lipophilic phase, but which has to contain neither micropores nor fillers. The former harbors the risk of volatile lead constituents permeating. The latter impairs the transparency, for example, of plastics based on plasticized cellulose esters. For this group of plastics, in particular cellulose propionate (CP), cellulose acetate (CA) and cellulose acetobutyrate (CAB), it has surprisingly been found that fatty alcohols having 16 to 20 carbon atoms, in particular oleyl alcohol and/or isostearyl alcohol are suitable as lipophilic liquid phase or as its main constituent. These substances can be used to produce lead masses with a temperature resistance of up to at least 40° C. They are, moreover, able to dissolve within the cellulose ester, for example like a type of primary plasticizer or—looking at it another way—to dissolve the ester. Provided the lipophilic liquid phase is still mixed homogeneously with the lead matrix, the amount which crosses into the plastic is negligibly small. Only when the lipophilic phase emerges from the lead mass and forms a liquid film on the surface of the lead due to warming does it penetrate into the material layers of the casing close to the lead surface.
Leads with a consistency which is adequately solid at room temperature are obtained if the content of fatty alcohol is in the range from 25% to 65% and a content of wax and/or fatty acid derivative of from 5% to 35% is observed. Such leads withstand temperatures up to about 50° C. The dissolution capacity of, in particular, saturated branched fatty alcohols, specifically of isostearyl alcohol, is increased if adipic esters and/or citric esters (e.g. di-n-butyl adipate=Cetiol B or acetyl tributylcitrate), known as plasticizers for cellulose esters, are added to the lead mass. These substances also improve the thermal stability of the lead mass irrespective of the oil absorption capacity of the casing. Stabilization and improvement of the oil retention ability is, as already mentioned above, achieved by microcrystalline waxes (paraffin waxes), or else by hydrogenated castor oil. The formulations according to the invention are further wherein by low filler contents (organic or inorganic fillers), or fillers may be dispensed with completely. The cellulose ester of the casing preferably has a plasticizer content of from 5 to 25%, in particular from 18 to 22%. This ensures adequate mechanical stability, but at the same time also good sharpenability and an adequate absorption capacity for a lipophilic phase which secretes from the lead mass.
To produce an encased cosmetic lead or a stick having a plastic casing, the lead masses, which are homogenized and molten at 70° C. to 100° C., are poured directly into a tubular plastic casing or, after mixing the raw materials, strands of lead are extruded and introduced into a plastic casing.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a cosmetic solid lead, it is nevertheless not intended to be limited to the specific exemplary details, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific examples that represent embodiments of the invention.
Base Formulation
All of the above percentages are percentages by weight.
The following is a list of raw material suppliers from which the above-mentioned materials are available:
This application claims the priority, under 35 U.S.C. § 119, of German patent application No. 203 19 911.1, filed Dec. 19, 2003; the entire disclosure of the prior application is herewith incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 203 19 911.1 | Dec 2003 | DE | national |
