MXPA99011312A - Concentrated fluid aqueous-alcoholic compositions of hydrogenated coconut or palm kernel oil alkylamidopropylbetaines - Google Patents

Abstract

Aqueous-alcoholic solutions of hydrogenated coconut or palm kernel oil alkylamidopropylbetaines with a betaine content of greater than 50%, which are fluid, stable and pumpable are described as occupying a well-defined zone of their betaine/water/ethanol ternary diagram. They are prepared by synthesis and quaternization of the amidoamine directly in the solvent medium in which they are defined.

Description

HYDRO-ALCOHOLIC CONCENTRATED HYDRO-ALCOHOLIC COMPOSITIONS OF HYDROGENATED COCONUT OR PALM OIL ALKYLAIDOPROPYLBETAINS COMPOUND Field of the Invention The invention relates to low viscosity, transparent and relatively colorless concentrated hydroalcoholic solutions which are stable in a temperature range between 5 and 50 ° C and containing at least 50% by weight of an alkylamidopropylbetaine corresponding to the general formula (I): CH3 R-CONH- (CH2) 3 -N + -CH2-COO- CH3 (I) wherein R represents the alkyl radical of a fatty acid fraction of the coconut oil or hydrogenated palm oil type, with an iodine number not greater than 1 (in grams of iodine per 100 g). The approximate composition of said fraction is, in percentages by weight: 50-65% lauric acid 15-26% myristic acid 8-14% palmitic acid 7- 15% stearic acid, the unsaturated fraction responsible for the low iodine value being represented by less of 1% oleic acid. In the following description, these alkylamidopropyl betaines will be referred to, for simplicity, as "betaines". Their solutions exhibit these qualities only if their composition is chosen accurately in a region of the betaine / ethanol / water diagram normalized to 100 by weight after correction of the NaCl present. STATE OF THE ART The betaines corresponding to the general formula (I) are amphoteric surfactants which are very well tolerated by the skin, exhibit excellent cleaning and foaming properties and are fully suitable for the preparation of a whole range of surfactant compositions, such as washing agents, cleaning agents (liquid products for hand cleaning), hair care compositions (shampoos) and body care compositions (shower gels and bubble baths). The preparation of this type of betaine is described in many documents and those skilled in the art are aware of such preparation processes, for example see US Pat. No. 3,225,074 (American Cyanamid). Such preparation consists in reacting a fatty acid or a fatty acid fraction with N, N-dimethyl-1,3-propanediamine (DMAP A) at temperatures between 140 and 200 ° C, and then quaternize the obtained tertiary amidoamine of general formula (II): CH3 R, -CONH- (CH2) 3-N CH3 (II) with monochloroacetic acid in the presence of an alkaline salt or of the corresponding salt of this acid, the quaternization reaction usually taking place in an aqueous medium. The alkaline chloride, which is usually sodium chloride, obtained as a by-product in the reaction, is generally left in this aqueous solution of betaine. These aqueous betaines are sold in a concentration of the order of 30% by weight. Attempts have frequently been made to industrially prepare betaine solutions that are as concentrated and fluid as possible, for the quite understandable reason of reducing transport and storage costs without sacrificing, however, the ease of handling. The person skilled in the art knows that when the concentration of an aqueous surfactant solution increases, its viscosity also increases. However, certain authors have tried to concentrate, by evaporation under reduced pressure, the solutions of betaines obtained according to the usual processes, but their viscosity increases rapidly and they become pasty at a concentration of around 40% by weight of betaine, continuing then the solidification as water is separated from such solutions: it is not possible to obtain concentrated solutions by means of this route. However, it has been reported in EP 0,302,329 (Th.Goldschmidt) that this difficulty could be partially overcome by adjusting the pH of the solution to a value between 1 and 4.5 with an inorganic acid (hydrochloric, sulfuric or phosphoric). In this way, said authors obtained solutions containing 43 to 44% by weight of betaine (or 53 to 54% solids) with a viscosity of the order of 1000 mPa.s at 25 ° C., corrosion problems that arise during storage and transport, together with the atypical pH of these betaine solutions, limit their use and, in addition, they gel at temperatures below 16 ° C. Another way is to obtain betaine in the form of powder through the spraying of fluid solutions at concentrations lower than 30%. Attempts have been made to redissolve these powders in suitable solvents, but the redissolution of such powders is impeded by the formation, when the powder comes into contact with the solvent, of lumps or gelled pastes which are practically impossible to redissolve or at least not within reasonable times that are compatible with industrial activity. The international patent application WO 97/12856 (Henkel) describes and claims a process for the preparation of surfactants of the betaine type with a low salt content (0.98 to 1.01% residual NaCl) by quaternization of tertiary amines and or tertiary amidoamines with sodium monochloroacetate in a hydroalcoholic mixture composed of 5 to 10% by weight of water and 35 to 50% by weight of ethanol and / or isopropanol, this reaction being followed by the separation of the fraction of precipitated salt, separation total solvent and readjusting the water content in the reaction medium in order to bring the solution to the desired concentration of active material, in this case 30%. The water / ethanol weight ratio claimed by the authors is typical for a process designed to remove the NaCl formed during the reaction. A composition of this type was the subject of patent US 4,705,893 (KAO), represented by a pentagonal zone of the betaine / water / ethanol ternary diagram defined by the triangular coordinates (80/10/10), (80/15 / 5), (40/55/5), (40 / 27.5 / 32.5) and (52.5 / 10 / 37.5). Both cases involve processes whose essential purpose is to obtain solutions of non-concentrated amphoteric surfactants, totally aqueous, with low salt content. The idea of the possible existence of fluid phase domains in an amphoteric / water / solvent surfactant system is familiar to the person skilled in the art. This idea is maintained in WO 95/14076 (Albright and Wilson), in reality without any specific description other than that of the individual examples offered in said publication, which are those that most closely approximate the conditions of the present problem, namely compositions of coconut- or lauryl-amidopropylbetaine-salt dissolved in a mixed solvent of the water / glycol type. The problem that still exists is to obtain solutions of alkylbetaines from hydrogenated coconut or palm oils that are as concentrated as possible, ie at least 50% by weight, transparent and relatively colorless, fluid and pumpable (viscosity less than 1000 mPa .s), stable at temperatures between 5 and 50 ° C for prolonged periods, in order to reduce the costs of packaging, transport and storage, easily manipulated and that can be formulated in the state in which they are with other surfactants, for Examples are alkyl ether sulphates, alkanolamides or other starting materials that are part, in particular, of the formulations for liquid soaps, shampoos, shower gels and other cosmetic preparations. The use of hydrogenated coconut oil is a limitation imposed by the need for these compositions intended for cosmetic use to have a better oxidation stability than would be expected for non-hydrogenated natural fractions. SUMMARY OF THE INVENTION The present invention offers a solution to this technical problem, which consists of preparing the alkylbetaine by quaternizing the reaction product of dimethylaminopropylamine with a fatty acid of coconut oil or hydrogenated palm in the presence of small amounts of ethanol, with the condition that, however, the system remains limited to a very precise and narrow region of the phase diagram as it will now be defined. Description of the Invention The calculation is determined in ternary compositions of betaine / water / ethanol, represented in the ternary diagram in reduced coordinates: B * = [betaine / (betaine + water + ethanol)] • 102 W * = [water / (betaine + water + ethanol)] • 102 E * = [ethanol / (betaine + water + ethanol)] • 102 where betaine has the sense of, and is measured as, betaine = solids - NaCl, where the ratio of 100% roughage is applied to the composition B * + W * + E * = 100 and where all the magnitudes with respect to betaine, solids, water, ethanol and NaCl are expressed on a weight basis, appearing the reduced magnitudes B *, W * and E * as percentage by weight. With this definition, the betaine considered is a crude betaine, ie a betaine consisting of an alkylamidobetaine as corresponding to formula I, with a few residues of reactants and a few reaction by-products not exceeding 3% by weight ( see Example 1). The compositions of the invention are those that obey the following relationships: 52% <; B * < 57% E * > 21% W * > 20% W * / W * + E * < 54% In the compositions of the invention, the NaCl is present at a maximum level of 6% by weight, beyond whose value these compositions become uncontrollable, even if only by the precipitation of the salt. The compositions according to the invention are capable of being stored for prolonged periods of at least three months, in the course of which no gelling, demixing, precipitation of salts or appreciable change in color or clarity in the temperature range between 5 and 50 ° C. These solutions also have the advantage of being relatively non-foaming in the concentrated state, which facilitates their handling. Another advantage resides in the fact that these concentrated solutions are sufficiently resistant to microbial invasion, so that it is unnecessary to add preservatives. These characteristics make these solutions particularly suitable for the preparation of cosmetic compositions. Another object of the present invention relates to the process for the preparation of these concentrated solutions, which consists in preparing the dimethylamidopropylamides of hydrogenated coconut or palm oils, intermediates, and quaternizing such intermediates with monochloroacetic acid in the presence of sodium hydroxide or monochloroacetate. Sodium directly in the chosen solvent medium, that is, adapting to the compositional standard: E * > 21% W * < 20% W * / W * + E * < 54% defined above. The following examples and counter-examples will allow a better understanding of the present invention. Example 1: Preparation of a hydrogenated coconut betaine containing about 52.4% by weight of betaine, ie 57.4% solids, whose reduced coordinates B * / W * / E * in the phase diagram are 55 / 22.5 / 22.5 (in percentage by weight). 1 / a- Preparation of coconut aminoamide (Mw = 309 g) In a reactor, 731 kg of coconut fatty acid with an iodine value of < 1, melted at 50 ° C. The reactor and its contents are bubbled with nitrogen and set at a temperature of 190 ° C. By means of a dip tube, 347 kg of dimethylaminopropylamine (DMAP A) are added over 4 hours. , the distillation waters are separated continuously. The mixture is maintained at 190 ° C under a nitrogen stream until the reaction product shows an acid number below 4.5 mg KOH / g. The mixture is cooled to 150 ° C, 100 kg of water is injected, by means of a dip tube, for 1 hour, and the resulting mixture is dried at 150 ° C while nitrogen is bubbled through it, to a Water content less than 0.1%. The system is cooled to 60 ° C, nitrogen bubbling is stopped and the reactor is emptied. The usual characteristics of the tertiary amidoamine thus obtained are as follows: 1 / b- Preparation of the concentrated solution of coconut betaine In another reactor, 233.7 kg of ethanol and 127.4 kg of water are charged at room temperature, followed by 169 kg of monochloroacetic acid. The mixture is set at 25 ° C and 473 kg of the amidoamine prepared in 1 / a are then slowly added, while the exothermicity is controlled so that the temperature does not exceed 40 ° C. They are then added, for 1 hour approximately 153 kg of 50% sodium hydroxide, while maintaining the temperature at 40 ° C, after which it rises slowly to 80 ° C. The mixture is maintained at this temperature until the amidoamine content reaches a stable value of 1%, taking the necessary precautions to ensure that the pH of a test sample, prediluted at 5% in water, is still between 10 and 10.5. After one hour, the mixture is cooled to 40 ° C and the pH is adjusted to 6.5 with 1% HCl solution. The precipitated NaCl fraction is separated by decantation, filtration or centrifugation. In this way, a concentrated solution of betaine having the following main compositions is obtained: a: 20 minutes at 105 ° C b: active material of betaine = solids - NaCl (including glycolate, free fatty acid and free amidoamine) c: values B *, W * and E * in the ternary diagram, after correcting the content in NaCl and subsequent normalization to 100 by weight and the following associated characteristics: d: maturation at 45 ° C. It is a fluid, transparent, easily pumpable solution and is stable at temperatures between 5 and 50 ° C. Counter-example 1: The operating conditions of stage 1 / b of Example 1, except as regards the loads of starting materials, which are adjusted to obtain a hydrogenated coconut betaine at a concentration of about 55.6% betaine, ie 60.5% solids, for which the corrected triangular coordinates B * W * / E * of NaCl in the phase diagram are 58.5 / 20.0 / 21.5 (in percentage by weight). A viscous, non-Newtonian, birefringent gel of the liquid crystal type is obtained which is difficult to handle and formulate at temperatures between 5 and 50 ° C. Counter-example 2: The operating conditions of step 1 / b of Example 1 are repeated , except as regards the loads of starting materials, which were adjusted to obtain a coconut betaine with an approximate concentration of 49.35% crude betaine, that is to say 63.75% solids, for the which the corrected triangular coordinates B *? V * / E * of NaCl in the phase diagram are 51.5 / 27.0 / 21.5 (in percentage by weight). A clear, fluid solution is obtained, consisting of a single phase in the region of room temperature (20-25 ° C) but which, at temperatures between 5 and 15 ° C, undergoes a rapid change to a mixture of two phases with a birefringent viscous gel phase and with a liquid supernatant phase. This heterogeneous product is difficult to use in this state. Counter-example 3: The same operating conditions are repeated as in step 1 / b of Example 1, except for the charges of starting materials, which were adjusted to obtain a coconut betaine with an approximate concentration of 53.95% betaine, ie 58.75% solids, for which the corrected triangular coordinates B * / W * / E * of NaCl in the phase diagram are 65.5 / 17.75 / 25, 75 (in percentage by weight). A solution is obtained that becomes heterogeneous after storage at 5 ° C.

Claims (1)

NOVELTY OF THE INVENTION Having described the present invention is considered as a novelty and, therefore, claimed as property contained in the following claims: 1. Compositions containing an alkylamidopropylbetaine corresponding to the general formula (I): CH3 I R- CONH- (CH2) 3 -N + -CH2-COO- CH3 salt, water and ethanol, in the form of fluid solutions that are easy to pump, transparent, relatively colorless, stable at temperatures between 5 and 50 ° C and having a viscosity less than 1000 mPa.s, the alkyl radical R of said alkylamidopropylbetaine being that of a fatty acid fraction or of coconut oil or hydrogenated palm oil with an iodine value of at most equal to 1, characterized in that the betaine components , water and ethanol, indicated as compositions reduced by B * = [betaine / (betaine + water + ethanol)] • 102 W * = [water / (betaine + water + ethanol)] • 102 E * = [ethanol / (betaine + water + ethanol)] • 102 where betaine has the sense of, and is measured as, betaine = solids - NaCl, are bound by the following ratios: 52% < B * < 57% E * > 21% W * > 20% W * / W * + E * < 54% that define their field of existence of the compositions as long as their salt content is less than 6% by weight. 2. Process for obtaining the compositions as described in claim 1, characterized in that it comprises preparing dimethylaminopropylamides of coconut oil or hydrogenated palm, as intermediates, and quaternizing the latter with monochloroacetic acid in the presence of sodium hydroxide or with monochloroacetate. Sodium directly in the water / ethanol solvent medium constituted to obey the following compositional standard E * = 21% W * < 20% W * / W * + E * < 54% having the reduced compositions E * and W * the meanings indicated in claim

1.