IT202000020212A1 - QUATERNARY AMMONIUM SALT FOR USE AS A CATIONIC SURFACANT - Google Patents

Description

TITLE: ?Quaternary ammonium salt for use as a cationic surfactant?

DESCRIPTION

FIELD OF THE INVENTION

The field of the present invention relates to a quaternary ammonium salt which can be used as a green alternative to common cationic surfactants.

STATE OF ART

According to IUPAC, the International Union of Pure and Applied Chemistry, green chemistry means ?the invention, design and use of chemicals and processes to reduce or eliminate the use and production of hazardous substances?. The main objectives of green chemistry include: prevention in the production of waste, rather than treating it after it has been produced; minimization of toxicity? of the chemicals used; the use of renewable raw materials whenever possible.

Quaternary ammonium salts are widely used as cationic surfactants for fabric softeners, anti-electrostatics, corrosion inhibitors, hair conditioners, dispersants, germicides, biocides.

Among said quaternary ammonium salts, cetrimonium chloride or behentrimonium chloride are known, mainly used as cationic surfactants in products for the cosmetic and/or household fields. Other types of quaternary ammonium salts that act as cationic surfactants and biocides are the polymers of quaternary ammonium salts such as, for example, silicone cocoamido quat or silicone dimeramido quat.

Products potentially containing quaternary ammonium salts as cationic surfactants are usually used daily and/or at high frequency by the consumer. Furthermore, they come into direct contact with the skin layer of the consumer and/or sometimes inhaled in the form of vapours.

Problem of the prior art

The common quaternary ammonium salts used as cationic surfactants are associated with some drawbacks, such as:

- they are difficult or non-biodegradable and therefore constitute a potential toxic waste, together with their chemical derivatives, if released into the environment;

- they are generally characterized by an unpleasant odor which makes them difficult to use. There? it becomes particularly relevant when included in cosmetic and/or personal cleansing products. For example, quaternary ammonium salts of chloride are often distinguished by a rotten fishy odor.

Also, one of the common synthetic processes of quaternary ammonium salts ? based on the Menshutkin reaction (or quaternization reaction); the latter provides for the use of polar solvents (for example methanol, ethanol) and an alkyl halide for the alkylation of the tertiary amino group; are these alkyl halides commonly synthesized in the laboratory with the use of solvents and/or toxic reagents (for example in the presence of pyridine)? factor that contributes negatively to eco-sustainability? of these salts.

Furthermore, when used in products for personal hygiene and cosmetics, they tend to accumulate in the skin (mainly cetrimonium chloride or CTAC) and to induce damage to the skin layer more? superficial promoting the onset of skin irritation and/or sensitization phenomena, especially if used at high frequency; they are sometimes responsible for inducing dehydration phenomena in the skin layer.

SUMMARY OF THE INVENTION

The Applicant has elaborated a quaternary ammonium salt which solves the problems of the prior art. Object of the present invention ? a quaternary ammonium salt of formula (I)

formula (I)

in which the substituent R1 ? selected from the group consisting of: hydrogen, methyl, isopropyl, sec-butyl, isobutyl, ethylenemethylthio, benzyl, para-hydroxybenzyl and 3-methylene-1Hindole, substituents R2, R3, R4 are independently selected from the group consisting of: methyl, ethyl , n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, the counter-anion X<- >? chosen from the group consisting of: acetate, tartrate and citrate, and n ? between 2 and 20.

A further object of the present invention are cosmetic compositions comprising the quaternary ammonium salt of formula (I) as cationic surfactant.

Advantages of the invention

The quaternary ammonium salt of formula (I) developed by the Applicant ? advantageous compared to common quaternary ammonium salts (quats) because:

- ? biodegradable and non-toxic, and therefore constitutes a green alternative to common quats;

- ? synthesizable without the use of toxic reagents and/or solvents, heavy metals, petrochemical derivatives or genetically modified organisms (or GMOs);

- ? available in liquid form for a pi? easy solubilization/dispersion in commercial product compositions;

- ? characterized by a more pleasant when compared to that of the common quaternary ammonium salts, whose counteranion is? commonly a halide, predominantly chloride. Specifically, the use of an organic counter-anion X<- > allows to obtain a salt of formula (I) characterized by a pleasant smell;

- the organic counter-anion (X-), plays a double role: on the one hand it acts as a neutralizing counter-anion of the quaternary ammonium salt of formula (I); on the other, it acts as an acid catalyst during the synthesis of the quaternary ammonium salt of formula (I), for the esterification reaction and the obtainment of the desired product. In this sense, the salt of the invention is made without the aid of heavy metal-based catalysts which can create toxicity problems. in the final product.

The quaternary ammonium salt of formula (I) can? be advantageously used as a cationic surfactant for cosmetic and personal cleansing use. For these purposes? advantageous because:

- ? able to moisturize the skin layer;

- not ? toxic, irritant n? sensitizer for the skin layer;

- does not accumulate at the level of the skin layer;

- ? suitable for palm-free cosmetic formulations/compositions;

- when used in hair cosmetics products, it facilitates combing wet hair and detangling dry hair while reducing the electrostatic phenomenon of hair fly-away;

- can? be used as the only cationic surfactant in cosmetic compositions for the hair, showing comparable or more? advantageous compared to common surfactants (see the Examples section); on the other hand, can? be used in association with common cationic surfactants; - acts as a stabilizer of emulsions/solutions and ? also compatible with other non-ionic and/or negatively charged ingredients;

- the use of the cosmetic product comprising the salt of formula (I) does not require a hot process.

DESCRIPTION OF THE FIGURES

Figure 1 ? Synthesis scheme of the salt of formula (I)

Figure 2 ? Tensiometer instrument (INSTRON Mod.5543)

Figure 3 ? Comparison between locks of hair treated according to example 2.1. Left strand: to the touch the hair is more? smooth and hydrated; to the eye more healthy. AND? also visible is a reduction of the frizz effect and the fly away effect; right lock: the hair is more? frizzy and ? instead, the occurrence of the fly away effect is visible.

Figure 4 ? Measurement of dry hair detangling.

Figure 5 ? Capacitance measurement? detangling on damaged Caucasian and Chinese hair treated with a 5% formula salt aqueous solution (IA1) and an equal amount? of a 5% aqueous solution of a 50:50 combination of CTAC/BTAC.

Figure 6 ? Thickness measurement evaluated on five strands of hair after 20 brush strokes.

Figure 7 ? Measurement of hair breakage after 10 brush strokes

Figure 8 ? Electrostatic charge measurement method.

DETAILED DESCRIPTION OF THE INVENTION

With reference to formula (I), the invention will described below in greater detail, with reference, where necessary, to the preferred embodiments thereof.

How already? indicated above, the quaternary ammonium salt of formula (I) provides that the substituent R1 is selected from the group consisting of: hydrogen, methyl, isopropyl, sec-butyl, isobutyl, ethylenemethylthio, benzyl, para-hydroxybenzyl and 3-methylen- 1H-indole. Table 1 below shows the structural formulas of the various preferred embodiments of the salt of formula (I) for each substituent R1.

Preferably, R1 ? hydrogen; in other words, the preferred embodiment of the salt of formula (I)? (IA).

For each of the embodiments indicated in Table 1 (IA-II), the substituents R2, R3, R4 are independently selected from the group consisting of: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

According to a preferred embodiment, at least two of the substituents selected from R2, R3, R4 are equal to each other and preferably selected from the group consisting of methyl, ethyl, n-propyl, n-butyl (for example, R2, R4) and the remaining substituent ? preferably selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

According to a preferred embodiment, at least two of the substituents selected from R2, R3, R4 are equal to each other and preferably methyl (for example, R2, R4) and the remaining substituent ? preferably selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

The substituents R2, R3 and R4 of the salt of formula (I) are preferably equal to each other and are selected from the linear substituents: methyl, ethyl, n-propyl, n-butyl.

The substituents R2, R3 and R4 of the salt of formula (I) are preferably equal to each other and constituted by the linear substituent methyl.

According to a preferred embodiment, the substituents R2, R3 and R4 of the salt of formula (IA) are equal to each other and constituted by the linear substituent methyl.

For each of the embodiments indicated in Table 1 (IA-II), the counteranion X<- >? chosen from the group consisting of: acetate, tartrate and citrate.

For embodiment (IA) of the quaternary ammonium salt of the invention, the counteranion X<- >? chosen from the group consisting of: acetate, tartrate and citrate.

Preferably, the counter-anion X<- >? acetate. The counter-anion acetate ? particularly advantageous for the purposes of the invention? Why? gives the quaternary ammonium salt of formula (I) a pleasant fruity smell.

According to a preferred embodiment of the salt of formula (I), the substituent R1 ? hydrogen, the substituents R2, R3 and R4 are methyl and the counteranion X<- >? the acetate group, cos? as in the following formula:

By polyglycerol-n we mean a polymer made up of an n number of units? structural based on glycerol; Note that commercially available n-polyglycerols are blends of polyglycerols, comprising 60% or more? of the n-polyglycerol of interest in which about 20% of the mixture is consisting of one or more its different counterparts, i.e. from polyglycerols-n with a number n of units? lower or higher repetitive than the one considered.

In particular, an n-polyglycerol in which n is 10 pu? be synthesized using green-type experimental methods, starting from natural vegetable glycerin, following the Cosmos and NaTrue standards.

Conversely, an n-polyglycerol in which n > 10 ? normally obtained with experimental methods known to those skilled in the sector which provide for the use of synthetic (non-vegetable) glycerine.

According to a preferred embodiment of the quaternary ammonium salt of formula (I), n? between 2 and 10, preferably between 2 and 6, preferably equal to 2, 3 or 4.

The salt of formula (I) ? preferably used as a cationic surfactant.

Preferably, the salt of formula (I) is used as a humectant, conditioning/softening agent, emulsifier, detergent, antistatic.

How already? anticipated, further object of the present invention ? a cosmetic composition comprising at least one quaternary ammonium salt formula (I) as cationic surfactant, in combination with optional excipients and/or diluents.

In the claimed cosmetic composition preferably the salt of formula (I) ? in a concentration between about 0.25% and 7% (w/w), preferably between 0.25% and 5%, preferably between about 0.5% and 5% (w/w), preferably between 1% and 5 About % (w/w), preferably equal to about 0.25%, 0.5%, 1%, 2%, 3%, 4%, 5% (w/w) by weight on the total weight of the composition.

In the cosmetic composition comprising the salt of formula (I), the latter can be the only cationic surfactant or can? be in combination with other cationic surfactants.

When used as the sole cationic surfactant in hair cosmetic compositions, the quaternary ammonium salt of formula (I) shows effects comparable or better than those of advantageous compared to common surfactants (see the Examples section).

When used in combination with other cationic surfactants (for example the polymeric cationic ones), at the dosages indicated above, the salt of formula (I) allows to avoid the use of silicone derivatives or to reduce that of other polymeric cations.

Cationic surfactants usable in combination with the salt of formula (I) are for example selected from the group consisting of: cetrimonium chloride (or CTAC), behentrimonium chloride (or BTAC), stearamidopropyl dimethylamine (or SAPDMA) and guar hydroxypropylthrimethylammonium chloride (or GHPTAC ), Dioleylethyl Hydroxyethylmonium Methosulfate (Tetranyl CO-40) and Behenoyl PG-Trimonium Chloride (Quartamine BTC-131).

The cosmetic composition preferably has a pH higher than 3.5 and lower than 6.0; preferably the cosmetic composition has a pH between 3.5 and 5, preferably between 4 and 4.5.

Without wishing to be bound by any theory, the Applicant believes that pH affects the capacity? conditioning agents of a cationic system; in this sense, at the pH values indicated above, the cosmetic composition has shown better capacity? conditioning agents (the hair was easier to comb than at other pH values of the composition).

The pH of the cosmetic composition can be regulated by including in the composition one or more? buffering agents; an average technician in the sector, on the basis of his basic knowledge, would be able to select without any difficulty? one or more buffering agents suitable for the purpose, choosing from those known in the state of the art.

The cosmetic composition? preferably in the form of a skin and hair cleansing product, a hair conditioning product or a skin moisturizing product.

When in the form of a cleansing product for the skin and hair, the cosmetic composition? preferably in the form of shampoo, conditioning shampoo (2 in 1), body wash.

According to a preferred embodiment, the cosmetic composition in the form of a detergent for the skin and hair comprises the salt of formula (I) in a concentration ranging from about 1 to 3%.

When in the form of a hair conditioning product, the cosmetic composition? in the form of a conditioner or oil non-oil hair conditioner.

According to a preferred embodiment, the cosmetic composition in the form of a hair conditioning product comprises the salt of formula (I) in a concentration ranging from about 1 to 7%.

When in the form of a skin moisturizing product, the cosmetic composition? preferably in the form of a moisturizer.

According to a preferred embodiment, the cosmetic composition in the form of a skin moisturizing cream comprises the salt of formula (I) in a concentration ranging from about 1 to 3%.

According to a preferred embodiment, the cosmetic composition is in the form of a hair conditioning product and preferably comprises a fatty alcohol with a number of carbon atoms between 14 and 22, preferably between 16 and 18.

Preferably, the fatty alcohol contained in the composition is selected from the group consisting of cetyl alcohol, stearyl alcohol or a combination of the foregoing (cetyl stearyl alcohol). According to a preferred embodiment, the quantity of alcohol ? between 1.10% and 2.20% by weight with respect to the amount of salt of formula (I).

The association with fatty alcohols advantageously favors combing, reducing the force required to comb the hair with greater smoothness of the comb as it passes.

The quaternary ammonium salt of formula (I) can? be advantageously obtained with the use of reactions known in the state of the art: by way of example, Figure 1 shows the synthesis scheme of the quaternary ammonium salt of formula (IA) starting from the acidification reaction of trimethylglycine (reaction I, figure 1), and subsequent organic acid esterification reaction catalyzed with the polyglycerol-n reagent (reaction II, figure 1). Thus, the desired quaternary ammonium salt product of formula (IA) and water are obtained.

It should be noted that, advantageously, water constitutes the only secondary product of the synthesis reaction of the quaternary ammonium salt of formula (I); in this sense, there is no formation and/or potential release of other compounds or chemical derivatives into the environment.

As for the quaternary ammonium salt of formula (IA), the synthesis reaction of the quaternary ammonium salt of formula (I) can be carried out starting from amino acid derivatives, characterized by a quaternary amino group at the carbon ? (N-R2, R3, R4).

Advantageously, the starting amino acid derivative (N-R2, R3, R4), the polyglycerol-n and the organic acid used in said chemical reactions are in turn obtained, as far as possible, with green synthesis methods according to the Cosmos standards and NaTrue and Regulation (EC) no. 1223/2009, thus contributing to sustainability? of the final product.

EXAMPLES

The Applicant reports below some examples for illustrative and non-limiting purposes of cosmetic use of the salt of formula (I).

Example 1 ? Examples of formulations comprising the salt of formula (I).

1.1 ? Conditioning shampoo

1.2 ? Conditioning shampoo (2 in 1)

1.3 ? Conditioning shampoo ?Green? (2 in 1)

1.4 ? Hair conditioner

1.5 ? Hair conditioner ?Oil non oil?

1.6 ? After-bath body cream

Example 2 ? Experimental evidence relating to cosmetic use.

2.1 - Visual evaluation

In the photo of Figure 3 ? It is possible to visually compare how a lock of hair treated with the cosmetic product comprising the salt of formula (IA1) (left) looks after drying and a lock of hair treated with a product comprising common quaternary cationic surfactants (quat) after drying (a right).

2.2 ? How to measure combability?

The Caucasian hair strands of the same origin were washed for 1 minute with a shampoo and then treated for 1 minute with a hair conditioning product formulated with the quaternary ammonium salt of the invention and with conditioning products formulated with various cationic ingredients (control).

The combability measurements? they were then performed with a tensiometer (INSTRON Mod. 5543, speed? 500 mm/min) on both wet and dry hair (Figure 2).

In order to facilitate the interpretation of the results obtained by the Applicant, it should be noted that for combability? means the force that the hair opposes to the sliding of the comb, i.e. the measure of the resistance that the hair exerts to the passage of the comb.

2.3 ? Measurement of dry hair detangling.

The graph of Figure 4 shows the dry detangling values of damaged Caucasian hair, obtained by carrying out the method according to Example 2.2.

In particular, the hair was combed following the treatment with a conditioning shampoo and with the conditioning shampoo of Example 1.1.

2.4 ? Capacitance measurement? detangling on damaged Caucasian and Chinese hair,

The graph of Figure 5 shows the values of dry detangling (ability to comb) of damaged hair of the Caucasian type, obtained by carrying out the method according to Example 2.2.

In particular, the hair was combed following the treatment with a 5% aqueous solution of formula salt (IA1) and an equal quantity of of a 5% aqueous solution of a 50:50 combination of CTAC/BTAC.

The result of the treatment comprising the salt of formula (IA1) shows better and significant benefits in the dry combing operation of the hair (method in Example 2.2), if compared to the result obtained with common quats, such as CTAC or BTAC.

Furthermore, the action of the formula salt (I) guarantees an evident sensation of hydration on damaged hair.

2.5 ? Measurement of hair thickness evaluated on five strands of hair after 20 brush strokes.

The evaluation ? been performed on strands washed with ?Green? of example 1.3, compared with two traditional products, market leaders. The results are shown in the graph in Figure 6, expressed as a percentage increase in hair volume (before and after treatment).

Even if the formulation with the salt of formula (IA1) has simply an exemplifying function, it presents results that are wholly comparable with the complex and sophisticated formulations of products of important multinational companies containing synthetic ingredients.

2.6 ? Measurement of hair breakage after 10 brush strokes

The evaluation ? been performed on strands washed with ?Green? of example 1.3, compared with the two traditional market-leading products (Control 1 and Control 2) previously used.

The results obtained from this comparison are visible in the graph of Figure 7.

2.7 ? Electrostatic charge measurement method (static charge accumulation - Lunn & Evans method).

The same strands of hair used for the combability tests? they were dried and combed 10 times in standard environmental conditions (20?C, relative humidity RH = 30%); subsequently ? Static charge (V) was measured with an appropriate sensor (3M Electrical Specialties Division, Model 709).

The detection ? been performed 10 times and ? the mean of the obtained values was calculated.

From the results shown in the graph of Figure 8, ? it has been found that a cosmetic product comprising the salt of formula (IA1) acts as an effective static charge reducer.

The effect of reducing the electrostatic charge? superior when compared to that obtained with market leading products comprising straight monoalkyl quaternary chains of CTAC and BTAC.

Claims (10)

CLAIMS 1. Quaternary ammonium salt of formula (I) in which the substituent R1 ? selected from the group consisting of: hydrogen, methyl, isopropyl, sec-butyl, isobutyl, ethylenemethylthio, benzyl, para-hydroxybenzyl and 3-methylene-1H-indole, the substituents R2, R3, R4 are independently selected from the group consisting of: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, the counteranion X<- >? selected from the group consisting of: acetate, tartrate and citrate, e n ? between 2 and 20. 2. Salt of formula (I) according to claim 1, wherein the counter-anion X<- >? acetate. 3. Salt of formula (I) according to claim 1 or 2, wherein R1 ? hydrogen. 4. Salt of formula (I) according to claim 1 or 2, wherein n? between 2 and 10. 5. Cosmetic composition comprising at least one salt of formula (I) according to any one of claims 1 to 4, as cationic surfactant. 6. Cosmetic composition according to claim 5, wherein the salt of formula (I) is in a concentration ranging from about 0.25% to 7.00% (w/w) by weight on the total weight of the composition. 7. Cosmetic composition according to claim 5 or 6, comprising the salt of formula (I) as sole cationic surfactant or in combination with other cationic surfactants. 8. Cosmetic composition according to any one of claims 5 to 7, having a pH ? above 3.5 and below 6. 9. Cosmetic composition according to any one of claims 5 to 8, in the form of a skin and hair cleansing product, a hair conditioning product, a skin moisturizing product. The cosmetic composition according to claim 9, wherein the hair conditioning product comprises fatty alcohols having a number of carbon atoms ranging from 14 to 22.