Partition coefficient ester compositions

None

The present invention is directed to ester compositions which result from the trans-esterification of a triglyceride having an iodine value of between 75 and 195 mg KOH/gm with a fatty alcohol having a melting point of between 35° and 75° C., followed by cooling and removal of the polar phase which results. Surprisingly, we have found the composition has unique properties when used in cosmetic applications. The fact that the reaction results in a complex mixture, which settles with time and is separated into a semisolid composition of the present invention and a discarded polar phase, gives a unique partition coefficient matched composition. By partition coefficient matched composition is meant a homogeneous, clear when heated above the melt point composition made up of compounds mutually soluble in each other.

Fatty acid esters have been used in the personal care market for many years. They are made by reacting fatty acids with fatty alcohols. The result is fatty ester and water, which is distilled off.

RC(O)OH+R′OH→RC(O)OR′+H 2 O

The reaction is run with the objective of making the most pure ester possible. The removal of the water using vacuum, drives the reaction and it is not uncommon to see purity of over 95%.

Prior to the present invention, those of ordinary skill in the art of making cosmetic esters were convinced products with little or no remaining reactants resulted in superior formulation performance. We have subsequently found that this assumption teaches away from our finding that specific compositions that are the result of trans-esterification of unsaturated triglycerides in which glycerin, monoglycerides, diglycerides, as well as the desired fatty ester result in a composition which when allowed to settle, yields an insoluble polar liquid phase on the bottom and a soft ester top phase that when used as a cosmetic ester has unique properties.

Without wanting to be bound by a particular theory, the cooling and settling process results in a composition of solid and liquid compounds, comingled in a buttery matrix, having similar enough polarity to allow miscibility, while expelling more polar materials which wind up in the lower phase upon cooling. We have dubbed this type of composition Partition Coefficient Compositions (PCC), since it is that factor which determines what will and will not remain in the mixture. These compositions have unique spreadability, emmoliency and compatibility with the human skin. We believe it is because the oils on the skin are likewise compositions, which are present on the skin because they have similar partition coefficients. This concept of matching partition coefficients of the oils produced using our process with that of the skin results in unique cosmetic products.

Objective of the Invention

It is an object of the present invention to provide a composition of related esters that provide are soluble in each other and have a soft buttery consistency, suitable for use on skin as soft emollient conditioning esters.

The present invention deals with ester compositions made by the trans-esterification reaction of a solid fatty alcohol, (i.e. one that has a melting point of between 35° C. and 75° C.) with a triglyceride having a iodine value of between 75 mg KOH/gm and 195 mg KOH/gm and optionally a catalyst, forming a mixture of unreacted triglyceride, monoglyceride, diglyceride, glycerin and unsaturated ester of the triglyceride reacted with the solid fatty alcohol. The composition is then cooled to 25° C., whereupon the polar components (namely glycerin and monoglyceride) settle to the bottom of the composition. These polar components are removed from the supernatant yielding a lipophillic composition, which is a soft solid.

An additional aspect of the present invention deals with a process for treating skin by applying to the skin an effective conditioning concentration of an ester compositions made by the trans-esterification reaction of a solid fatty alcohol, (i.e. one that has a melting point of between 35° C. and 75° C.) with a triglyceride having a iodine value of between 85 mg KOH/gm and 175 mg KOH/gm and optionally a catalyst, forming a mixture of unreacted triglyceride, monoglyceride, diglyceride, glycerin and unsaturated ester of the triglyceride reacted with the solid fatty alcohol. The composition is then cooled to 25° C., whereupon the polar components (namely glycerin and monoglyceride) settle to the bottom of the composition. These polar components are removed from the supernatant yielding a lipophillic composition, which is a soft solid.

In a preferred embodiment, the effective conditioning concentration ranges from 0.1% to 25% by weight.

In a more preferred embodiment, the effective conditioning concentration ranges from 1% to 15% by weight.

In order to understand the composition of the present invention one must understand the chemistry of the trans-esterification reaction. This reaction is quite different from the esterification in many respects. Firstly, the reactants, the trans-esterification reaction reacts a triglyceride with an alcohol, whilst the esterification reacts a fatty acid with a fatty alcohol, secondly, the reactants, the trans-esterification reaction results in a number of products of differing polarity (partition coefficient), whilst the esterification reaction results in the desired ester only. Thirdly, the reaction temperature for trans-esterification is lower ranging from 150-160 C whilst the esterification ranges from 170-200° C. This has implications on color, odor and performance. Finally, the trans-esterification reaction can be run without catalyst, which results in a sustainable product that can be certified as ECCOCERT, whilst the esterification process requires catalysts, often tin catalysts.

(A) Raw Materials

The concentration of the starting triglyceride in the final composition after removal of the polar phase ranges from 1-5% by weight.

R 1 is at least 50% by weight C18 unsaturated selected from the group consisting of oleyl and linoleyl;

R 2 is saturated alkyl having 13 to 23 carbon atoms.

The concentration of the starting alcohol after removal of the polar phase ranges from 1-10% by weight.

Partially Reacted Products

Monoglyceride

R 1 is at least 50% by weight C18 unsaturated selected from the group consisting of oleyl and linoleyl.

R 2 is saturated alkyl having 13 to 23 carbon atoms.

These are formed in a 1:2 ratio of monoglyceride 1 to monoglyceride 2.

The concentration of this component after removal of the polar phase ranges from 0-5% by weight.

Diglyceride

R 1 is at least 50% by weight C18 unsaturated selected from the group consisting of oleyl and linoleyl.

R 2 is saturated alkyl having 13 to 23 carbon atoms.

The concentration of this component after removal of the polar phase ranges from 5-15% by weight.

Fully Reacted Products

R 2 OC(O)R 1

R 1 is at least 50% by weight C18 unsaturated selected from the group consisting of oleyl and linoleyl.

R 2 is saturated alkyl having 13 to 23 carbon atoms.

This is the predominant product. The concentration of this component after removal of the polar phase ranges from 60-89% by weight.

Co-Product Glycerin.

The concentration of this component after removal of the polar phase ranges from 0-5% by weight.

R 1 is at least 50% by weight C18 unsaturated selected from the group consisting of oleyl and linoleyl.

R 2 is saturated alkyl having 13 to 23 carbon atoms.

It is important to understand that oleyl conforms to the structure CH 3 (CH 2 ) 7 —CH═CH—(CH 2 ) 8 — and linoleyl conforms to the following structure CH 3 (CH 2 ) 4 —CH═CH—CH 2 —CH═CH—(CH 2 ) 8 —, both are C18 unsaturated cis groups, oleyl substituted at 9 position and linoleyl at the 9 and 12 position. It is this critical structure that disrupts the crystallinity of the resulting composition and gives the unique properties. Likewise the solid crystalline nature of the R 2 group is needed for functionality in each of the components of the composition to function.

After the reaction is complete, the reaction mass becomes cloudy, due to the presence of glycerin. The glycerin, generated during the reaction is too polar to be soluble in the diglyceride, triglyceride and desired ester. Consequently upon ceasing mixing, it rapidly separates into a lower layer. As the composition cools, it solidifies, resulting in an easy extraction of the glycerin and polar components soluble in the glycerin. This upper layer solid layer contains the various diglycerides (semisolid), triglycerides (liquid) and the desired product (solid). When heated it exhibits a melt point having a range of about 5° C. and is clear when above its melt point. This clarity of product is indeed verification of the fact that the components contained therein have a compatible partition coefficient as demonstrated by the clarity of the phase and as contrasted with the haze present before separation. The glycerin phase, containing the majority of the monoglycerides is likewise clear when removed, again showing similar partition coefficient of the components of the composition.

The process as defined in the current invention is therefore self cleaning, easy to practice, and results in a unique product composition, as will be disclosed subsequently, the composition contains (a) solid plate like crystals (the fully reacted product), (b) a semisolid amphorus material (the diesters) and a liquid product (triglyceride). Photomicrographs show that the composition has (a) a highly structured solid matrix (b), an amphorous phase distributed therein and (c) a liquid phase dispersed evenly therein. The phases match up the letters above.

Surprisingly, the compositions of the present invention have unique and heretofore unappreciated advantages over more traditional methods, vis-à-vis cosmetic properties, including spread, skin feel and emollient properties.

It is also an important part of the present invention that natural triglycerides be used as raw materials for the preparation of the compositions of the present invention Naturally occurring triglycerides do not have a singly fatty component, but have a distribution of fatty acids selected by nature and evolution of the plant over many years. This natural composition, in part is responsible for unique skin properties observed when one uses the composition of the present invention on skin, in either a serum or an emulsion.

The compositions of the present invention when applied to skin have outstanding spread profiles, absorption rates and conditioning properties offering heretofore unavailable alternative compounds to traditional synthetic non-polar compounds such as Petroleum, silicone and synthetic compounds used in topically applied products in the form of O/W, W/O and anhydrous.

The products produced by the process of the present invention is directly responsible for the, surprising and unexpected, effects including but not limited to spread profiles, absorption rates and conditioning properties to the skin and hair spread profile in combination with the target ester compound, wherein, if just a simple esterification process were utilized the effect would not be observed. For example a simple esterification of stearyl alcohol and oleic acid to form, Stearyl Oleate, would not contain the spread and absorption profile of a Stearyl oleate obtained from the reaction of Stearyl Alcohol and Olive oil that contains the described acid composition in the second paragraph above. Utilizing these natural oils as described in paragraph two above allows for this effect to be noticed, which is driven by the trans-esterification process.

The present invention discloses an ester compositions made by the trans-esterification reaction of

(a) a solid fatty alcohol, having a melting point of between 35° C. and 75° C.;

(b) with a triglyceride having a iodine value of between 75 and 195 mg KOH/gm and

(c) optionally a catalyst,

forming a mixture of unreacted triglyceride, monoglyceride, diglyceride, glycerin and unsaturated ester of the triglyceride reacted with the solid fatty alcohol;

said trans-esterification conducted at as temperature of 150-200° C. for 4 to 10 hours;

said composition is allowed to cool without agitation to 25° C., over a period of at least 30 minutes,

whereupon a top solid layer forms and a bottom liquid layer forms;

finally, the bottom layer is removed from the mixture by resulting in

a lipophillic composition of the present invention.

In a preferred embodiment the fatty alcohol has a melt point of between 40 and 60° C.

In a preferred embodiment the fatty alcohol has a melt point of between 35 and 50° C.

In a preferred embodiment the fatty alcohol has a melt point of between 50 and 75° C.

In a preferred embodiment the iodine value of the triglyceride ranges from 85-95 mg KOH/gm.

In another preferred embodiment the iodine value of the triglyceride ranges from 100-175 mg KOH/gm.

In a preferred embodiment the reaction is conducted with no catalyst.

In a preferred embodiment the reaction is conducted with between around 0.1 and 0.3% by weight stannous oxylate.

In a preferred embodiment said trans-esterification is conducted at as temperature of 150-170° C. for 4 to 10 hours.

In a preferred embodiment said trans-esterification is conducted at as temperature of 150-170° C. for 7 to 10 hours.

In a preferred embodiment the composition is allowed to cool without agitation to 25° C., over a period of at least 60 minutes,

In a preferred embodiment the bottom layer is removed from the mixture by simply opening the valve at the bottom of the vessel.

Additionally, the invention is directed to a trans-ester composition comprising:

(a) between 1-5% by weight of;

(B) between 1-10% by weight of;

R 2 OH

(C) between 0-5% by weight of a mixture of monoglycerides conforming to the following structure:

(D) between 5-15% by weight of a mixture of diglycerides conforming to the following structure:

between 60-89% by weigh an ester conforming to the following structure:

R 2 OC(O)R 1

and

between 0-5% by weight of glycerin conforming to the following structure:

wherein;

R 1 is at least 50% by weight C18 unsaturated selected from the group consisting of oleyl and linoleyl.

R 2 is saturated alkyl having 13 to 23 carbon atoms.

An additional aspect of the present invention deals with a process for treating skin by applying to the skin an effective conditioning concentration of an ester compositions made by the trans-esterification reaction of a solid fatty alcohol, (i.e. one that has a melting point of between 35° C. and 75° C.) with a triglyceride having a iodine value of between 85 mg KOH/gm and 175 mg KOH/gm and optionally a catalyst, forming a mixture of unreacted triglyceride, monoglyceride, diglyceride, glycerin and unsaturated ester of the triglyceride reacted with the solid fatty alcohol. The composition is then cooled to 25° C., whereupon the polar components (namely glycerin and monoglyceride) settle to the bottom of the composition. These polar components are removed from the supernatant yielding a lipophillic composition, which is a soft solid.

In a preferred embodiment, the effective conditioning concentration ranges from 0.1% to 25% by weight.

In a preferred embodiment, the effective conditioning concentration ranges from 1% to 20% by weight.

In a more preferred embodiment, the effective conditioning concentration ranges from 10% to 15% by weight.

In a preferred embodiment the process for conditioning skin is delivered in a serum.

In a preferred embodiment the process for conditioning skin is delivered in a emulsion.

Hair and skin are made up of protein. Protein in turn is composed of amino acids, which are assembled into what is referred to as primary structure. The peptide bond as it is referred to by biochemists is referred to as polyamides by organic chemists. The amino acid structure has a secondary structure which relates to hydrogen bonding, giving each protein a three dimensional structure. There are also disulfide bonds between sulfur bearing amino acids. For the most part, unless you are relaxing or perming hair you do not want to do anything to alter the protein structure.

Additionally, hair and skin contain oils. The build up of which constitutes the major portion of what is commonly called “soils”. Some of these materials are superficial and can be easily removed while others soils are located deeply within the hair and skin and are not easily removed. An understanding of these materials and how they function is critical to understanding healthy hair and skin.

A key article related to this analysis is entitled Hair Lipids and their contribution to perception of hair oiliness. Koch, J. et al, Hair Lipids and their contribution to perception of hair oiliness, J. Soc. Cosmet. Chem. 33, 317-326, November 1982.

The Koch article defines two types of oils, the first referred to as “external oiliness” and the second as “internal oiliness”. The article points out that some of the oil that designated external oil is superficial and needs to be removed in cleaning. The remainder of the oil remains strongly absorbed onto the hair and in the cuticle and can only be removed by strong extraction. It has been shown by consumer testing that the internal oil does not contribute to the consumer perception of oiliness on hair or skin. It does however function as what Koch calls a “storage capacity” for oil. This is important because the internal oil works its way to the surface, replenishing the oils fund in the natural state. This mechanism explains why hair and skin become oily even when washed on a quite regularly basis. Healthy hair and skin have oil present on them.

Koch also points out that the nature of the oil and not only its concentration has a major effect upon the consumer perception of oiliness both on hair and on skin.

We have found that the topical application of the compounds of the present invention to cleaned skin and hair results in a more rapid re-establishment of the natural balance of the internal oils of the hair and skin. When the ester is applied to the hair or skin as taught in our process, effects the speed in which the healthy internal oil composition is achieved on the hair or skin. The oil spreading from the internal oil storage, results in a highly desirable feel on the hair and skin as it is perceived by the consumer.

The oils observed on the hair vary considerably in terms of polarity. If the extraction of oils is not the same based upon this difference in polarity, the extracted oils will not be the same as those removed by shampooing. Koch developed extraction methodologies that both showed the composition of internal and external oils and related directly to those extracted by detergents. This outstanding analytical work has allowed for both structure elucidation and quantification of the components of both internal and external oils. The methodology finds both non-polar oils like triglycerides, and far more polar components like mono acyl glycerides commonly found on the hair and skin. Since these classes of compounds differ appreciably in polarity, an extraction of external oils must pick the polar and non-polar oils from the hair and leave the internal oils in tact. It was determined in the Koch reference that the best extraction solvent for the polar and non-polar oils on the hair as external oils is a mixture of water and chloroform. The presence of water has a profound effect upon cleaning hair. Water swells the hair during shampooing, which is thought to have an impact on the availability of the internal oiliness especially just under the cuticle. The object of the experiment of Koch et al was to identify the external oils extracted from the hair during cleansing.

It was determined that the “average commercial shampoo” removes 40-60% of the total oils in the hair. This quantity matches up well with the extraction method of Koch. The internal oils are extracted using extreme methods, specifically, the extractions conducted by Soxhlet extractions with boiling ether and water for 16 hours.

The composition of the oils removed by detergents is called “external oils”.

The composition of oils are not removed by detergents is the so called “Internal oils”.

Composition of Internal Oils

The fact that the composition of internal oil and external oil is not identical indicates there is some preferential absorption of compounds rich in internal oil but lean in the external oil. In short the hair and skin “dump” the less desirable oils out of the structure.

Comparison of External Oils v. Internal Oil Location

Difference in Oils by Location. Internal to External Ratio

High I:E ratios indicate a component that is held within the hair and does not readily pass to the outside. Cholesterol Esters are strongly retained on the inside by a 4.2:1 ratio. Monoglycerides and Squalene are roughly equal showing little preference for internal or external. Free fatty acids, triglycerides and cholesterol esters favor the external phase.

We have determined that when the esters of the present invention are applied to the hair after cleansing, there is initially a repair of the cuticle. The application of our ester does not effect the trans epidermal water loss, which is the coating is non-occlusive. This allows water to pass from inside to out and allows for a more rapid equilibrium of internal oil to the surface of the hair or skin that has been denuded of external oils. Prior to the present invention, large amounts of oils and quaternary compounds were applied after washing to minimize damage. Our methodology allows the oils that are in the skin and hair to come out making a natural conditioning.

The efficient and expeditious establishment of the equilibrium of oils within the hair and skin and those on the outside results in cosmetically elegant appearance, healthy balance and natural equilibrium.

The traditional treatment methods using fatty quaternaries, fatty alcohols, mineral oils and the like all result in a hair and skin having materials that are not normally present on hair or skin and are in fact materials that need to be removed in the next wash. This is seen as greasiness on skin or build up on hair.

Raw Materials Fatty Alcohol

Examples 1-15

The compounds used as raw materials are available from a variety of sources including Sasssol in Germany. The following are examples

In the above chart, CAS stands for chemical abstract number;

MW stands for molecular weight in grams/mole

OH Val stands for hydroxyl value in mg KOH/gm

MP stands for melting point in degrees C.

and Bp stands for boiling point in degrees C.