FR3092502A1 - Formulation of microcapsules with reinforced aminoplast membrane - Google Patents

Abstract

Formulation of microcapsules containing a liquid or solid active ingredient protected by an aminoplast membrane modified by the introduction of tannic acid and / or polyphenols in order to increase the stability of these microcapsules. Said formulation comprises the following steps: - Dispersion or emulsion of a solid or liquid active principle in an aqueous phase containing - an amino resin, crosslinkable by condensation, of the aminoplast family - a protective colloid of preferably anionic polymer type - optionally of a surfactant - in situ polymerization of this resin in the presence of tannic acid or of phenolic compounds resulting from tannins such as flavonoids, protoanthocyanidin, or resulting from the reaction between gallic acid and glucose, or resulting from lignins . The formulation according to the invention reinforces the strength of the wall of the microcapsules and gives them better preservation during storage in media rich in surfactants and promotes adhesion of the capsule to the textile.

Description

Formulation of microcapsules with reinforced aminoplast membrane

Object of the invention

The invention relates to the improvement of a process for the preparation of microcapsules by aminoplast resins in order to increase their stability in media rich in surfactants such as detergents and softeners.

State of the art

The invention relates to the field of the encapsulation of active ingredients for prolonged use in detergent media and in particular for the formulation of fabric softeners.

It is well known that one can prolong the action of an active substance by a process of microencapsulation, that is to say that the active principle is emulsified to obtain fine droplets whose dimensions are governed by the emulsion. On these droplets, one or more polymer films are deposited which protect the active principle from its immediate environment, ensure fixation on a support (textile for example) and also allow control of the release of the active principle. This release is done by two main phenomena diffusion or extraction through the polymer film or by rupture or abrasion of this film. It is therefore necessary for this protective film to have properties which can be difficult to combine for the same material: good mechanical resistance, suitable permeability taking into account the properties of the active ingredient but also those of the ambient environment, and adhesive properties. adapted to the support. We can see that the protective film will be, depending on the intended application, prepared using several polymer materials and various additives.

Microencapsulation corresponds to all the technologies allowing the preparation of individualized microparticles, consisting of a coating material containing an active ingredient. The synthesis or development of microcapsules or microparticles has become over the years an interesting way for the protection and controlled release of various products such as perfumes, cosmetic agents, biocides, etc. Its field of application continues to progress in the fields of food processing, pharmacology, cosmetology, detergents and the textile industry.

There are many processes which are generally classified according to their nature:

• The so-called physico-chemical processes
• Mechanical processes
• Chemical processes

In physico-chemical processes, there are processes based on the precipitation of a polymer in solution by the use of a non-solvent or by variation of the ionic strength, pH or temperature (coacervation).

Mechanical processes are based on spraying, drop forming and extrusion techniques. The most commonly used processes are spray-drying, drop freezing (spray chilling/prilling), coating in a fluidized air bed or even spheronization/extrusion.

Finally, the chemical processes allow the formation of the coating material by in situ synthesis using monomers or oligomers unlike the previous processes which use preformed polymers or waxes. Polymerization techniques such as radical polymerization, or polycondensation techniques are used.

The majority of industrial perfume encapsulation techniques initially involve so-called in situ polycondensation processes of melamine (or urea) and formaldehyde historically described for transfer paper applications in patents from BASF US4406816 and from Printex FR2501059A1. Improvements have been made to address the problems posed by the properties of detergents and are taught in patents FR316303, EP1797946A2, EP099404B1, WO2013092375A1 and EP2111214B1.

Interfacial polymerizations or polycondensations are also described, especially those involving isocyanate monomers. This process was initially claimed by Bayer, US4193889, US4428978, US4874832 for transfer or phytosanitary paper applications. It was then applied for perfume encapsulation (WO2007004166A1).

These patents provide a lesson on the improvement of the properties of the membrane of microcapsules by limiting the diffusion of the perfume in these aggressive environments while guaranteeing an ideal dispersion thus allowing a great efficiency. Indeed, the detergent media for which the process of the invention is intended are aqueous media whose physicochemical properties can be very different: pH, ionic strength, hardness (concentration of calcium and magnesium ions), rheological properties, etc. The surfactants used can be nonionic, anionic, cationic. A certain number of additives can be added: Bleaching agent, Enzymes, Brighteners, Complexants, Ion exchangers…

The state of the art as regards the improvements made to the method of encapsulation by in situ polycondensation of aminoplast resins to prevent the diffusion of perfumes, is summarized in the following documents.

Patent WO217186604 claims the addition of diols to reinforce the capsule membrane, but no example showing the effectiveness of this claim is given.

The patent EP2111214B1 close to the previous patent claims the use of an aromatic diol such as resorcinol in order to co-react with the aminoplast resin to reduce the diffusion of the perfume in media such as softeners.

Patents WO2013092375A1 and EP3099404B1 claim that the use of a polyisocyanate introduced into the perfume strengthens the membrane, making it more airtight and makes it possible to reduce the quantity of aminoplast resin to be used. However, several things limit the use of the invention. The perfume concentration seems limited to 30% in the dispersion and the use of a polyisocyanate, introduced into the oil, can lead to the denaturation of the latter with regard to the reactivity of the isocyanate functions with respect to the composition. fragrant. Finally, the use of an isocyanate reagent with a certain toxicity requires its elimination or its total consumption.

Patent EP1797946A2 teaches that increasing the polymerization temperature to temperatures equal to or greater than 100°C (process under pressure) makes it possible to reduce the diffusion of perfume in media such as fabric softeners.

Finally, patent FR3016303 claims a so-called “double encapsulation” process comprising polymerization of (alkoxy)silanes by hydrolysis-condensation (sol-gel) and polycondensation of aminoplast resin.

The previous review of the state of the art with respect to methods for improving the resistance of aminoplast membranes in media rich in surfactants does not reveal the use of tannic acid or its derivatives for reinforcing aminoplast membranes which is the subject of the present invention

Detailed description of the invention

The object of the invention is to obtain core-shell aminoplast microcapsules obtained by a process comprising the following steps:

1. Formulation of an aqueous phase by dispersion in water of an aminoplast resin of the urea-formaldehyde or melamine-formaldehyde type and of a protective colloid, preferably polymeric and anionic
2. Addition of an oily phase (ie perfumed oil or perfume) to this aqueous phase to form an oil-in-water emulsion
   1. Obtaining an emulsion whose diameter of the droplets is between 0 and 100µm
3. Stage of polymerization of the membrane of the capsules by heating and change of pH
   1. Addition of an additive of the tannic acid type or its derivatives
   2. Stage of cross-linking of the membrane of the capsules by heating
   3. Introduction if necessary of a "reducer" of formaldehyde.
4. Cooling
   1. Introduction if necessary of a colloidal stabilizer.

The preferably demineralized water preferably represents between 50 and 99% of the aqueous phase, more preferably between 70 and 95% and even more preferably between 85 and 95%.

The method according to the invention is distinguished by the use of a protective colloid serving to prevent the agglomeration of the particles and also participates in the formation of the membrane of the capsules by associating with the partially cationized aminoplast resin during the polymerization. It is introduced at a mass concentration of between 0.1 and 30%, preferentially between 1 and 10% and even more preferentially between 1 and 5%. This protective colloid is preferably anionic and of the acrylate-acrylamide copolymer type. However, the nature of the copolymer that can be used to stabilize the emulsion and the microcapsules can be extended to all the copolymers known to those skilled in the art for encapsulation by in situ polymerization of aminoplast resin such as synthetic polymers such as maleic anhydride copolymers (ethylene, styrene, isobutylene, etc.), acrylic copolymers bearing sulphonate functions such as lupasol PA140 (formerly BASF), acrylic copolymers, polysulphonates and polycarboxylates. It can also be derived from natural polymers such as cellulose derivatives such as carboxymethyl cellulose or else of the polysaccharide type such as gum arabic.

The amine water-soluble prepolymer used in the invention that can be used can be of the urea formaldehyde, benzoguanamine-formaldehyde, urea-formaldehyde, melamine-formaldehyde type. This resin can be more or less partially methylolated and have a more or less high concentration of alkoxyimine functions. The most commonly used resins are in the form of pre-condensates of methylolated 1,3,5-triamino-2,4,6-triazine (melamine-formaldehyde) marketed under the name LURACOLL (formerly BASF) or Cymel (Allnex). It is also possible to synthesize the resin by reaction between an aldehyde (formaldehyde, acetaldehyde, glyoxal etc.) and an amine or amide compound such as urea, melamine or benzoguanamine. This resin is introduced between 1 and 20% in the aqueous phase, more preferentially between 5 and 15% even more preferentially between 7 and 12%.

By perfumed oil, also referred to as perfume, is meant any compound or composition having the effect of producing a pleasant odor recognizable by those skilled in the art as "perfume". Scented oil is in liquid form and is generally composed of many molecules of very different chemical natures, the list of which is not exhaustive below: aldehyde, ketone, alcohol, ether, ester, terpene, nitrogen molecules, sulfur or still from essential oils. It can be natural or synthetic.

For the implementation of the invention, the perfumed oil generally represents between 1 and 50% _mass of the totality of the mixture, preferentially between 20 and 45% _mass and more preferentially between 35 and 45% _mass of the mixture.

The emulsion is obtained by dispersion using a device capable of generating shear known to those skilled in the art, such as a rotor-stator disperser or a high-pressure homogenizer.

If necessary, in order to allow the condensation reaction of the aminoplast resin to be catalyzed, the pH is lowered to a value between 2 and 5, preferably between 3.5 and 4.5 using a weak acid such as methanoic acid. or ethanoic acid. The application is not limited to the use of these two molecules, other acids known to those skilled in the art can be used in order to catalyze the polycondensation reaction of the resin.

The main object of the invention is the introduction into the reaction medium of tannic acid, a polyphenol, with the IUPAC name beta-D-Glucose pentakis (3,4-dihydroxy-5- ((3,4,5 -trihydroxybenzoyl)oxy)benzoate) in the form of a solution or not and alone or as a mixture. It can be associated or substituted by tannins or constituents of tannins such as flavonoids, protoanthocyanidin, derivatives of the reaction between gallic acid and glucose, and lignins. It can be synthetic or natural in nature. It is introduced at a concentration of between 0.05 and 30%, preferentially between 0.5 and 10% and even more preferentially between 1 and 5%.

As specified in the description (step 3.c), it is possible to add one or more reagents likely to reduce the concentration of free formaldehyde. These formaldehyde “reducers” are compounds capable of reacting with the free formaldehyde present in the reaction medium. They are known to those skilled in the art. To name a few, we find in this category molecules such as urea and its derivatives, melamine, reducing agents such as sodium sulphite, beta-di ketone or diethyl malonate.

Generally (step 3.d), in order to stabilize the particles against sedimentation or creaming leading to the aggregation of the microcapsules, anionic, cationic, zwitterionic or nonionic water-soluble polymers are used. These macromolecules will have the role of stabilizing the particles by bringing electrostatic and steric repulsion between the particles and by increasing the viscosity of the dispersion. The number and nature of the products that can be used is very wide. For example, a wide range of products can be used either from natural macromolecules such as cellulose or starch, polycarbohydrates or polysaccharides such as gum arabic, agar agar or even xanthan, or even macromolecules synthetic such as poly(vinyl alcohol)s or poly(vinyl pyrrolidone), polyalkylene oxide) or polyacrylics. The concentration of the stabilizer in the final mixture can be between 0 and 5%, preferably between 0 and 1.5%

The microcapsules described according to the invention are stable without addition of additive in media composed of cationic species such as fabric softeners, however in the context of the invention it is possible to add a cationic polyelectrolyte to the formulation in order to improve if necessary the fixation of the capsules on the textile. Preference will be given to polyelectrolytes such as cationic acrylamide copolymers such as polyquaternium 7 or even the acrylamide-acrylamido-propyl trimonium chloride copolymer marketed under the trade name Salcare. However, many other types of cationic copolymers or homopolymers can be used such as the other polyquaterniums (polymer contraction and quaternary ammonium). They can be introduced pure or as a mixture at a mass concentration of between 0 and 10% and more preferably between 0 and 5%.

The microcapsules for use in fabric softener-type detergents or in media rich in surfactants are obtained according to the steps below:

1. Dissolution of the protective colloid, preferably of the copolymer type (acrylamide-acrylate) and of the polyamine resin of the melamine-formaldehyde type, in water with moderate agitation
2. Adjustment of the pH of the solution to a pH between 3.5 and 5, preferably between 3.8 and 4.5 using a weak acid solution, preferably methanoic acid.
3. Addition of the perfumed oil under dispersion using a shearing mixer. The size of the droplets must be between 1 and 100 μm, preferably between 5 and 50 and even more preferably for a fabric softener application between 10 and 40 μm. The speed of the mixer and its geometry are chosen by the person skilled in the art in order to obtain the size distribution adapted to the application
4. Adjustment of the temperature of the dispersion to a value comprised between 40 and 60° C. preferentially between 45 and 55° C. for a duration comprised between 10 minutes and 2 hours preferentially between 20 minutes and 1 hour and even more preferentially between 20 minutes and 40 minutes.
5. Addition of tannic acid and/or its derivatives in the form of a solution
6. Increase in the reaction temperature to a temperature of between 70 and 95° C., preferably between 70 and 85° C. for a period of between 30 minutes and 6 hours, preferably between 1 hour and 3 hours.

The following part presents a series of examples illustrating the invention but it is understood that the invention is not limited to these simple applications. Finally, in many examples, isopropyl myristate is added to the perfumed oil in order to be able to be extracted and quantified during the study of the permeability of the membrane of the microcapsules in a fabric softener.

Examples

Example 1 - Preparation of microcapsules containing a mint oil according to the prior art

In a 600cm beaker³, are introduced into 100g of permuted water, at room temperature and with stirring, 12g of acrylic copolymer - acrylamide 131R (SNF Floerger) and 11.5g of melamine-formaldehyde resin (Cymel 385, Allnex). The pH of the solution is adjusted to a value equal to 4.3 using a solution of formic acid (20%). Under mechanical stirring, 75g of Mint Arvensis (Aromafleur) scented oil are added to the solution. The mixture is emulsified with an ultraturrax T50 (IKA) until the desired size distribution is obtained. The reaction medium maintained under mechanical stirring is heated at 50° C. for 30 minutes. The temperature of the dispersion is then increased to 80° C. and maintained for 2 hours. After 60 minutes, the pH is reduced with formic acid to pH 4. The solution is finally cooled to room temperature.

Example 2 - Preparation of microcapsules containing a perfumed oil according to the prior art

In a 600cm beaker³, 12 g of 131R copolymer (SNF Floerger) and 11.5 g of Cymel 385 (Allnex) are introduced into 100 g of deionized water, at room temperature and with stirring. The pH of the solution is adjusted to a value equal to 4.3 using a solution of formic acid (20%). Under mechanical stirring, 75g of a mixture of 50% isopropyl myristate and Kenner perfumed oil (Aromafleur) are introduced into the solution. The mixture is emulsified with an ultraturrax T50 (IKA) until the desired size distribution is obtained. The reaction medium maintained under mechanical stirring is heated at 50° C. for 30 minutes. The temperature of the dispersion is then increased to 80° C. and maintained for 2 hours. After 60 minutes, the pH is reduced with formic acid to pH 4. The solution is finally cooled to room temperature.

Example 3 - Preparation of microcapsules containing a mint oil according to the invention

In a 600cm beaker³, 12 g of 131R copolymer (SNF Floerger) and 11.5 g of Cymel 385 (Allnex) are introduced into 100 g of deionized water, at room temperature and with stirring. The pH of the solution is adjusted to a value equal to 4.3 using a solution of formic acid (20%). Under mechanical stirring, 75g of Mint Arvensis (Aromafleur) scented oil are added to the solution. The mixture is emulsified with an ultraturrax T50 (IKA) until the desired size distribution is obtained. The reaction medium maintained under mechanical stirring is heated at 50° C. for 30 minutes. The pH of the solution is then increased to 5.3 with sodium hydroxide (40%). 15g of a tannic acid solution (40wt%) is added to the mixture. The temperature is increased to 80° C. and maintained for 2 hours. At 70°C, the pH of the mixture is adjusted to pH approximately 4.5 with formic acid (20%). After 60 minutes, the pH is lowered with formic acid (20%) to pH 4. The solution is then cooled to room temperature.

Example 4 - Preparation of microcapsules containing a perfumed oil according to the invention

In a 600cm beaker³, 12 g of 131R copolymer (SNF Floerger) and 11.5 g of Cymel 385 (Allnex) are introduced into 100 g of deionized water, at room temperature and with stirring. The pH of the solution is adjusted to a value equal to 4.3 using a solution of formic acid (20%). Under mechanical stirring, 75g of Kenner perfumed oil (Aromafleur) are introduced into the solution. The mixture is emulsified with an ultraturrax T50 (IKA) until the desired size distribution is obtained. The reaction medium maintained under mechanical stirring is heated at 50° C. for 30 minutes. The pH of the solution is then increased to 5.3 with sodium hydroxide (40%). 15g of a tannic acid solution (40wt%) is added to the mixture. The temperature is increased to 80° C. and maintained for 2 hours. At 70°C, the pH of the mixture is adjusted to approximately pH 4.5 with formic acid (20%). After 60 minutes, the pH is lowered with a formic acid solution (20%) to pH 4. The solution is then cooled to room temperature.

Example 5 - Preparation of microcapsules for dosage containing a perfumed oil prepared with an acrylic-acrylamide copolymer according to the invention (catalysis by formic acid)

In a 600cm beaker³, 12 g of 131R copolymer (SNF Floerger) and 11.5 g of Cymel 385 (Allnex) are introduced into 100 g of deionized water, at room temperature and with stirring. The pH of the solution is adjusted to a value equal to 4.3 using a solution of formic acid (20%). Under mechanical stirring, 75g of a mixture of 50% isopropyl myristate and Kenner perfumed oil (Aromafleur) are introduced into the solution. The mixture is emulsified with an ultraturrax T50 (IKA) until the desired size distribution is obtained. The reaction medium maintained under mechanical stirring is heated at 50° C. for 30 minutes. The pH of the solution is then increased to 5.3 with sodium hydroxide (40%). 15g of a tannic acid solution (40wt%) is added to the mixture. The temperature is increased to 80° C. and maintained for 2 hours. At 70°C, the pH of the mixture is adjusted to pH approximately 4.5 with formic acid (20%). After 60 minutes, the pH is lowered by adding formic acid (20%) to pH 4. The solution is then cooled to room temperature.

Example 6 - Preparation of microcapsules for dosage prepared with an acrylic-acrylamide copolymer containing a perfumed oil according to the invention (catalysis by acetic acid)

In a 600cm beaker³, 12 g of 131R copolymer (SNF Floerger) and 11.5 g of Cymel 385 (Allnex) are introduced into 100 g of deionized water, at room temperature and with stirring. The pH of the solution is adjusted to a value equal to 4.3 using an acetic acid solution (80%). With mechanical stirring, 75g of a 50% isopropyl myristate mixture and Kenner perfumed oil ( Aromafleur) are introduced to the solution. The mixture is emulsified with an ultraturrax T50 (IKA) until the desired size distribution is obtained. The reaction medium maintained under mechanical stirring is heated at 50° C. for 30 minutes. The pH of the solution is then increased to 5.3 with sodium hydroxide (40%). 15g of a tannic acid solution (40wt%) is added to the mixture. The temperature is increased to 80° C. and maintained for 2 hours. At 70°C, the pH of the mixture is adjusted to pH approximately 4.5 with acetic acid (80%). After 60 minutes, the pH is lowered with acetic acid to pH 4. The solution is then cooled to room temperature.

Example 7: Preparation of microcapsules containing a perfumed oil for dosage prepared with a sulfonic acid-acrylamide copolymer according to the prior art

In a 600cm3 beaker are introduced at room temperature and with stirring: 100g of an 8% solution of Lupasol PA 140 (formerly BASF), 50g of deionized water and 15 of methylolated melamine formaldehyde resin (Cymel 385, Allnex) . The pH is adjusted to 4.3 with an acetic acid solution (80%). The stirring speed is increased to 1000 rpm and then 60 g of a 50% mass mixture of isopropyl myristate and Kenner perfumed oil (Aromafleur) are added. The mixture is emulsified using an ultraturrax T50 (IKA) until the desired diameter is obtained. Under mechanical stirring, the temperature of the dispersion is increased and maintained at 50° C. for 30 minutes. The temperature is then increased to 80° C. and maintained for 2 hours. After 60 minutes, the pH is lowered with formic acid to pH 4. The solution is then cooled to room temperature.

Example 8: Preparation of microcapsules for dosage prepared with a sulfonic acid-acrylamide copolymer containing a perfumed oil according to the invention.

In a 600cm beaker³, 100 g of an 8% solution of Lupasol PA 140 (formerly BASF), 50 g of deionized water and 15 g of methylolated melamine-formaldehyde resin (Cymel 385, Allnex) are introduced at room temperature and with stirring. The pH is adjusted to 4.3 with an acetic acid solution (80%). The stirring speed is increased to 1000 rpm and then 60 g of a 50% mass mixture of isopropyl myristate and Kenner perfumed oil (Aromafleur) are added. The mixture is emulsified using an ultraturrax T50 (IKA) until the desired diameter is obtained. Under mechanical stirring, the temperature of the dispersion is increased and maintained at 50°C for 30 minutes. The pH of the solution is then increased to 5.3 by sodium hydroxide (40%) and 15g of a tannic acid solution (40wt%) is added to the mixture. The temperature is increased to 80° C. and maintained for 2 hours. At 70°C, the pH of the mixture is adjusted to pH approximately 4.5 with formic acid (20%). After 60 minutes, the pH is lowered with formic acid to pH 4. The solution is then cooled to room temperature.

Example 9 - Preparation of microcapsules containing a perfumed oil for dosage prepared with an acrylic acid-acrylamide copolymer according to the invention

In a 600cm beaker³, 12 g of acrylate-acrylamide copolymer 150R (SNF Floerger) and 11.5 g of Cymel 385 (Allnex) are introduced into 100 g of deionized water, at room temperature and with stirring. The pH of the solution is adjusted to a value equal to 4.3 using a solution of formic acid (20%). Under mechanical stirring, 75g of a 50% mass mixture of isopropyl myristate and Kenner perfumed oil (Aromafleur) are introduced into the solution. The mixture is emulsified with an ultraturrax T50 (IKA) until the desired size distribution is obtained. The reaction medium maintained under mechanical stirring is heated at 50° C. for 30 minutes. The pH of the solution is then increased to 5.3 by sodium hydroxide (40%), 15 g of a solution of tannic acid are added to the mixture. The temperature is increased to 80° C. and maintained for 2 hours. At 70°C, the pH of the mixture is adjusted to approximately pH 4.5 with formic acid (20%). After 60 minutes, the pH is lowered with formic acid to pH 4. The solution is then cooled to room temperature.

Example 10 - Preparation of microcapsules containing a perfumed oil for dosage prepared with an acrylate-acrylamide copolymer according to the invention

In a 600cm beaker³, 12 g of 131R copolymer (SNF Floerger) and 11.5 g of Cymel 385 (Allnex) are introduced into 100 g of deionized water, at room temperature and with stirring. The pH of the solution is adjusted to a value equal to 4.3 using a solution of formic acid (20%). Under mechanical stirring, 75g of a 50% mass mixture of isopropyl myristate and Kenner perfumed oil (Aromafleur) are introduced into the solution. The mixture is emulsified with an ultraturrax T50 (IKA) until the desired size distribution is obtained. The reaction medium maintained under mechanical stirring is heated at 50° C. for 30 minutes. After thickening The pH of the solution is then increased to 5.3 with sodium hydroxide (40%), 7.5g of a tannic acid solution is added to the mixture. The temperature is increased to 80° C. and maintained for 2 hours. At 70°C, the pH of the mixture is adjusted to pH 4.5 with a formic acid solution (20%). After 60 minutes, the pH is lowered with formic acid to pH 4. The solution is then cooled to room temperature.

Example 11 - Preparation of a fabric softener comprising scented microcapsules

The formulations were prepared with a standard unscented fabric softener base whose composition is not known. 1wt% of microcapsules is introduced with stirring into the softening base. The samples are stored at 40°C.

Example 12 - Stability of microcapsules in a softener

The formulations prepared according to Example 6 are centrifuged at 10,000 rpm for 20 minutes. 1g of subnatant is then taken and diluted in 3g of acetonitrile. After 10 minutes, this mixture is centrifuged and the supernatant is removed. If necessary, the supernatant is filtered by a 0.45 μm syringe filter. The solution is then injected by gas chromatography (Autosystem XL, Perkin Elmer) to determine the concentration.

Stability of microcapsules in a softener base at 40°C (% of perfume released):

Storage time at 40°C '(week(s)) 1 4 8 Example 2 control 11.6% 40% 61% Example 5 6% 8.9% 9.8% Example 6 7.8% 15.6% 16.2% Example 7 54% 67% Example 8 30% 31% Example 9 30% 35% 38% Example 10 6.6% 20% 29%

Example 12 - Olfactory performance of perfumed microcapsules in a softener base

1g of softener containing microcapsules prepared according to the invention is added to 1L of tap water. 100g of fabric are immersed and impregnated for 30 minutes. The fabrics are then wrung out and dried in the open air. The samples are evaluated once dry by a panel of 5 people. The panelists give a score between 0 (no smell) and 5 (strong smell) on the olfactory power of the textile after rubbing.

Olfactory performance of the microcapsules synthesized according to the invention:

test Without friction Immediately after treatment After 4 weeks Test after aging of the softener for 4 weeks at 40°C – immediately after treatment Example 1 control 0 3 2 0 Example 3 0 4 3 4 Example 4 0 4 3 4

Claims (12)

Formulation of microcapsules consisting of a solid or liquid, dispersed or emulsion active substance and a membrane prepared from an aminoplast resin and tannic acid alone and/or polyphenols and/or their respective mixture. A microcapsule formulation prepared according to claim 1, wherein the aminoplast resin is melamine formaldehyde, urea-formaldehyde or any reaction between an aldehyde and melamine or urea. Formulation of microcapsules prepared according to claims 1 and 2, in which a protective colloid and/or a surfactant is added to stabilize the emulsion and the microcapsules A microcapsule formulation prepared according to claim 3, wherein the protective colloid is a copolymer of acrylic acid and acrylamide A microcapsule formulation prepared according to claim 3, wherein the protective colloid is a terpolymer of acrylic acid, an acrylic ester and acrylamide A microcapsule formulation prepared according to claim 3, wherein the protective colloid is a maleic anhydride copolymer A microcapsule formulation prepared according to claim 3, wherein the protective colloid is a preferably anionic cellulose derivative such as carboxymethyl cellulose A microcapsule formulation prepared according to claim 3, wherein the surfactant is anionic of the sulfate, carboxylate or sulfonate type. Formulation of microcapsules prepared according to claims 1 to 8, in which the tannic acid is added neat or in solution Formulation of microcapsules prepared according to claims 1 to 8, in which are added polyphenols such as tannins and lignins or the reaction products between gallic acid, or ellagic acid and glucose. Use of the microcapsules prepared according to claims 1 to 10 in aggressive media such as media rich in surfactants Fabric softener containing microcapsules produced according to claims 1 to 10