Plurality of microcapsules and polymer dispersions comprising the same

Abstract

The invention concerns a plurality of microcapsules comprising an active ingredient encapsulated in a cross-linked polymeric shell, wherein the crosslinked polymeric shell comprises a dispersant. A homogeneous dispersion comprising (a) a polymer matrix and (b) 0.1-15 % by weight, preferably 1-10% by weight relative to the total weight of the homogeneous dispersion of the plurality of microcapsules is also disclosed.

Description

Plurality of microcapsules and polymer dispersions comprising the same

[0001] The present invention concerns a plurality of microcapsules. The invention also concerns a dispersion comprising a polymer matrix and microcapsules comprising an active ingredient encapsulated in a crosslinked polymeric shell. The invention also concerns a process for making the plurality of microcapsules and a process for making the dispersion and a process for producing a polymeric article

[0002] The encapsulation of active ingredients has been developed as a technical option to protect such active ingredients from undesired and premature interactions with other components of formulations or reaction mixtures. The encapsulation is useful in particular to provide reaction mixtures, for example polymerization mixtures or polymer processing mixtures, which allow for improved processes and final products due to a better controlled use of active ingredients such as catalysts.

[0003] WO-A-2018 / 172431 in the name of the applicant discloses a series of microcapsules having a polymeric shell with a pore size less than 1 nm which are generally suitable for such purpose. US6831116 concerns novel modifying agents containing a sharply-melting crystalline polymer ingredient, preferably a side chain crystalline (SCC) ingredient, and an active chemical ingredient. Such modifying agents, especially when in the form of particles, can be placed in contact with a matrix, will not modify the matrix below the crystalline melting point Tp, but will rapidly modify the matrix above Tp. The active chemical ingredient can react with the matrix, catalyze a reaction of the matrix, or inhibit a reaction of the matrix. The reference does not seem to disclose encapsulation with cross-linked shells

[0004] In order to ensure desired product quality of the final polymer product, it appears advantageous to provide homogeneous dispersions of microcapsules in the polymer matrix. US9771478 discloses compositions and methods for increasing microcapsule dispersion in self-healing paint and coating applications, and more particularly for non-covalent functionalization of polymeric microcapsule shell walls for improved dispersion in polymeric material formulations. This reference teaches modification of the microcapsule shell through adding one or more ethoxy-functionalized dispersants to the material before formation of the plurality of microcapsules is complete.

[0005] The invention now makes available microcapsules suitable for the encapsulation and delivery of an active, in particular to polymer production and processing processes and allowing to obtain homogeneous dispersions of microcapsules in a polymer matrix, notably an epoxy matrix..

[0006] The invention consequently concerns a plurality of microcapsules comprising an active ingredient encapsulated in a cross-linked polymeric shell, wherein the crosslinked polymeric shell comprises a dispersant.

[0007] The plurality of microcapsules according to the invention generally displays a particularly good compatibility with polymer matrices, in particular an epoxy matrix, including for solid active ingredients. The plurality of microcapsules according to the invention allows for effective encapsulation and delivery of active ingredients, in particular solid active ingredients. If appropriate, the presence of the dispersant, which may suitably be added as a component of the starting monomer composition (e.g. a composition C2 as described below) throughout the polymerization process allows for a particularly precise and reproducible particle size distribution in the plurality of microcapsules.

[0008] In the plurality of microcapsules according to the invention, the cross-linked polymeric shell further comprises a dispersant.

[0009] A first group of suitable dispersants is selected from amphiphilic copolymers bearing functional groups that adsorb onto pigment surfaces such as in particular :

[0010] - Styrene-maleic anhydride copolymers (e.g. modified with polyether chains);

[0011] - Poly(meth)acrylic acid copolymers modified with grafted polyethylene glycol (PEG) or

[0012] polypropylene glycol (PPG);

[0013] - Polyester-polyurethane copolymers;

[0014] - Polyurethanes with anchor groups (e.g., hydroxyl, phosphate, sulfonate, carboxyl);

[0015] - Block copolymers (e.g., poly(styrene-beta-ethylene oxide));

[0016] - Polyvinylpyrrolidone-co-vinyl acetate;

[0017] - Hyperbranched polyester-amides or dendritic polymers with pigment-affine end

[0018] groups (carboxylic acids, phosphonates, etc.).

[0019] A second group of suitable dispersants is selected from cationic polymers such as e.g; quaternary ammonium polymers and cationic polyacrylates.

[0020] A third group of suitable dispersants is selected from lignosulphonates such as e.g. sodium lignosulphonates and / or potassium lignosulphonates.

[0021] A fourth group of suitable dispersants is selected from acidic polyethers having a number-average molecular weight (Mn) between 500 and 20,000 g / mol, said polyethers comprising at least one terminal or pendant group selected from carboxylic acid, sulfonic acid, phosphoric acid, or salts thereof. Suitably the polyether backbone comprises ethylene oxide, propylene oxide, or butylene oxide units.

[0022] A fifth group of suitable dispersants is selected from aqueous or non-aqueous solutions of salts of unsaturated polyamineamides and acidic polyesters, wherein said polyamineamides are derived from condensation of unsaturated dicarboxylic acids and polyamines such as diethylenetriamine or triethylenetetramine. Said acidic polyesters suitably comprise repeating units derived from dicarboxylic acids selected from maleic acid, fumaric acid, and itaconic acid, and diols selected from ethylene glycol, diethylene glycol, or 1,4-butanediol.

[0023] A sixth group of suitable dispersants is selected from salt forms of polyester- or polyamide-based dispersants. Such salt forms can be obtained in particular by neutralization with a base selected from ammonia, sodium hydroxide, potassium hydroxide, or alkanolamines.

[0024] The dispersant is suitably selected from the group consisting of dispersants having a polar end- group in particular those capable of binding to pigments, lignosulphonates and cationic polyacrylates. A particular suitable dispersant is DISPERBYK (R) 2030.

[0025] The content of dispersant is generally from 1 wt. % to 5 wt. %, preferably from 2 wt. % to 4 wt. % relative to the total weight of the cross-linked polymeric shell.

[0026] In a preferred aspect, the dispersant is covalently bonded to the crosslinked polymeric shell. This can be achieved, for example, by selecting a dispersant which can form a copolymer with at least one other components of the crosslinked polymeric shell. For example, an acrylate group containing dispersant, for example a polyacrylate dispersant, can be copolymerized with (meth)acrylate monomers and / or oligomers as described herein below, to form the cross-linked polymeric shell.

[0027] In a preferred aspect, the dispersant is homogeneously distributed in the cross-linked polymeric shell. Without wishing to be bound by any theory, it is believed that the presence of dispersant across the polymeric shell is advantageous to ensure a particularly efficient encapsulation of active ingredient, in particular a solid active ingredient, while facilitating the release upon application of a stimulus.

[0028] Particle size: The different D50 values can be determined through microscopy and statistical analysis of the results. The microcapsules used in the homogeneous dispersion according to the invention have a mean diameter as defined above, said diameter being measured by methods well known to the skilled person in the art, e.g. by a light scattering technique (for example using a Mastersizer 3000 equipped with a hydro SV measuring cell), or by image analysis of optical microscopy pictures, or by image analysis of electronic microscopy pictures. When the D50 is determined using a light scattering technique, the value is based on volume. When the D50 is determined using an image analysis technique, the value is numerical.

[0029] I

[0030] “Monomer” refers to a molecule which can undergo polymerization thereby contributing constitutional units to the essential structure of a macromolecule.

[0031] “Oligomer” refers to a macromolecule comprising a repetition of monomers, preferably a repetition of less than 10 monomers.

[0032] « Topological polar surface area » is understood to denote the molecular polar surface area , i.ie the surface of a molecule belonging to polar atoms. The topological polar surface area for the purpose of the present invention is calculated using a method presented by Ertlet al.of Novartis Pharma in the Journal of Medical Chemistry (J. Med. Chem. 2000, 43, 3714-3717, https: / pubmed.ncbi.nlm.nih.gov / 11020286 / ), in which the atomic contribution to the PSA is determined through a tabulation based on the chemical structure.

[0033] The topological polar surface area of the plurality of microcapsules according to the invention is often equal to or greater than 60 Ų preferably equal to or greater than 65 Ų. The topological polar surface area is often equal to or lower than 90 Ų preferably equal to or lower than 75 Ų.

[0034] In a particular aspect , the plurality of microcapsules according to the invention generally has an average diameter D50 of from 1 to 80 μm, often from 5 to 50 μm, preferably from 10 to 20 μm.

[0035] In another embodiment, the plurality of microcapsules according to the invention generally has an average diameter D50 of from 20 to 80 μm, often from 31 to 80 μm, preferably from 40 to 50 μm.

[0036] Said D50 values are preferably by volume.

[0037] Theseaspects of the plurality of microcapsules according to the invention allows in particular to enhance the speed of formation of a homogeneous dispersion, for example, in a polymer matrix.

[0038] In another particular aspect of the plurality of microcapsules according to the invention, the cross-linked polymeric shell has a cross-linking density of equal to or greater than 0.5 mmole / g, preferably equal to or greater than 0.7 mmole / g. In this aspect, the cross-linked polymeric shell usually has a cross-linking density of equal to or smaller than 4 mmole / g, preferably equal to or smaller than 1.5 mmole / g and in some aspects smaller than 1.0 mmole / g or equal to or smaller than 0.9 mmole / g.

[0039] The crosslinking density can be determined by dividing the functionality of oligomers or monomers by their average molar masses weighted by the conversion rate, of the reactive groups, including but not limited to cross-linkable precursor group of the cross-linking bond. Functionality is the number of reactive groups in the respective oligomers or monomers composing the shell.

[0040] Preferred crosslinkable groups useful in the present invention are selected from acrylate, methacrylate, and epoxy.

[0041] It has been found that these particular aspects are particularly advantageous in terms of mechanical and release properties of the microcapsules, especially in combination with a polymer matrix.

[0042] In the plurality of microcapsules according to the invention, the shell encapsulates an active ingredient. The active ingredient can be a solid at 25°C. In the absence of indication, the skilled person readily understands that the melting point of a compound is given at atmospheric pressure (1013,25 kPa). When the active ingredient is a solid, it generally has an average diameter D50vol of from 1 to 50 μm, often from 2 to 40 μm, preferably from 3 to 10 μm.

[0043] The active ingredient can also be a liquid at 25°C and 1013,25 kPa pressure. The active ingredient may be a reactive agent, which may be released through a specific external stimulus, including but not limited to a change in pH, exposure to ultra-violet radiation, a change in temperature, exposure to mechanical stress and / or any combination thereof. In order to achieve said release by external stimulus, certain components of the shell may be selected, as disclosed in for instance EP 3548529.

[0044] In that aspect, the active ingredient is often selected from a catalyst, a UV absorber, a lubricant and a flame retardant, a pigment and a liquid crystal material.

[0045] The active ingredient can be suitably selected from, for example: a crosslinking agent, a hardener, an organic or metal catalyst (such as an organometallic or inorganometallic complex of platinum, palladium, titanium, molybdenum, copper, zinc) used for polymerising polymer-, elastomer-, rubber-, paint-, adhesive-, sealant-, mortar-, varnish-, or coating formulations;

[0046] a dye or pigment intended for elastomer-, paint-, coating-, adhesive-, sealant-, mortar-, or paper formulations

[0047] a fragrance (in accordance with the list of molecules established by the International Fragrance Association (IFRA) and available on the website www.ifraorg.org) intended for detersive products such as cleaning / washing products, home care products, cosmetic and personal care products, textiles, paints, coatings;

[0048] an aroma / flavouring agent, a vitamin, an amino acid, a protein, a lipid, a probiotic, an antioxidant, a pH corrector, a preservative for food compounds and animal feed;

[0049] a softener, a conditioning agent for detersive products, cleaning / washing products, cosmetics and personal care products. In this regard, the active agents that may be used are for example as listed in the US patents U.S. Pat. No. 6,335,315 and U.S. Pat. No. 5,877,145;

[0050] an anti-discolouration or anti-fading agent (such as an ammonium derivative), an antifoaming agent (such as an alcohol ethoxylate, an alkylbenzene sulfonate, a polyethylene ethoxylate, an alkylethoxysulfate or alkylsulfate) intended for detersive products and cleaning / washing products and home care products;

[0051] a brightening agent, also referred to as a colour activating agent (such as a stilbene derivative, a coumarin derivative, a pyrazoline derivative, a benzoxazole derivative, or a naphthalimide derivative) intended for detersive products, cleaning / washing products, cosmetics and personal care products;

[0052] a biologically active compound such as an enzyme, a vitamin, a protein, a plant extract, an emollient agent, a disinfecting agent, an antibacterial agent, an anti-UV agent, a medicament intended for cosmetic and personal care products, and textiles. Among these biologically active compounds the following may be mentioned: vitamins A, B, C, D and E, para-aminobenzoic acid, alpha hydroxy acids (such as glycolic acid, lactic acid, malic acid, tartaric acid, or citric acid), camphor, ceramides, polyphenols (such as flavonoids, phenolic acid, ellagic acid, tocopherol, ubiquinol), hydroquinone, hyaluronic acid, isopropyl isostearate, isopropyl palmitate, oxybenzone, panthenol, proline, retinol, retinyl palmitate, salicylic acid, sorbic acid, sorbitol, triclosan, tyrosine;

[0053] a disinfecting agent, an antibacterial agent, an anti-UV agent, intended for paints and coatings;

[0054] a fertiliser, a herbicide, an insecticide, a pesticide, a fungicide, a repellent, or a disinfecting agent intended for agrochemical products;

[0055] a fire resistant agent, also known as a flame retarding agent, (for example a brominated polyol such as tetrabromobisphenol A, a halogenated or non-halogenated organophosphorus compound, a chlorinated compound, an aluminum trihydrate, an antimony oxide, a zinc borate, a red phosphorus, a melamine, or a magnesium dihydroxide) intended for use in plastic materials, coatings, paints, and textiles;

[0056] a photonic crystal or a photochromophore intended for use in paints, coatings, and in polymer materials that form curved and flexible screens;

[0057] a product known to the person skilled in the art under the accepted nomenclature Phase Change Materials (PCMs) that is capable of absorbing or releasing so-called ‘latent’ heat when going through a change in a phase, intended for the storage of energy. Examples of PCMs and the applications thereof are described in “A review on phase change energy storage: materials and applications”, Farid et al., Energy Conversion and Management, 2004, 45(9-10), 1597-1615. By way of examples of PCMs, mention may be made of molten salts of aluminum phosphate, ammonium carbonate, ammonium chloride, cesium carbonate, cesium sulfate, calcium citrate, calcium chloride, calcium hydroxide, calcium oxide, calcium phosphate, calcium saccharate, calcium sulfate, cerium phosphate, iron phosphate, lithium carbonate, lithium sulfate, magnesium chloride, magnesium sulfate, manganese chloride, manganese nitrate, manganese sulfate, potassium acetate, potassium carbonate, potassium chloride, potassium phosphate, rubidium carbonate, rubidium sulfate, disodium tetraborate, sodium acetate, sodium bicarbonate, sodium bisulfate, sodium citrate, sodium chloride, sodium hydroxide, sodium nitrate, sodium percarbonate, sodium persulfate, sodium phosphate, sodium propionate, sodium selenite, sodium silicate, sodium sulfate, sodium tellurate, sodium thiosulfate, strontium hydrophosphate, zinc acetate, zinc chloride, sodium thiosulfate, paraffinic hydrocarbon waxes, polyethylene glycols.

[0058] In a particular embodiment the active ingredient is a lubricant. Examples of suitable lubricants include but are not limited to oils such as mineral oils, polyalphaolefins, polyglycols, synthetic esters, phosphate esters, triglyceride esters, polyol esters, fatty acids, vegetal oils, silicone oils, polyethers, perfluoropolyethers, as well as solid lubricants, such as notably amides, such as erucamide or ethylene bis(stearamide), and synthetic or natural waxes (paraffins).

[0059] In a preferred embodiment of the homogeneous dispersion according to the invention the active ingredient is selected from the group consisting of a catalyst, a curing agent, a latent accelerator of curing of an epoxy resin, and polyurethane catalysts.

[0060] Suitable latent accelerators may be selected, for example, from amine latent accelerators, in particular polyamine latent accelerators. Particular examples are selected from modified polyamines, e.g. Ancamine2014 FG.

[0061] Suitable polyurethane catalysts are selected, for example from amine polyurethane catalysts, for example aliphatic, alicyclic and bicyclic compounds having at least one tertiary amino group. Specific examples include but are not limited to diazabicycloundecene (DBU) 1,6-Bis-(N,N-dimethylamino)-nhexane, (N,N-dimethylamino)cyclohexane, 2-(N,N-dimethylamino)ethanol, N-methylmorpholine, Dimorpholinodiethylether, Dimethylaminoethoxyethanol, Triethylenediamine,  bis(2-dimethylaminoethyl)ether), N-tris-3-(N,N-dimethylamino)propyl1,3,5-triazine and N-N-Dimethyldipropylene triamine.

[0062] In the plurality of microcapsules according to the invention,  the microcapsules are generally monodisperse.

[0063] For the purposes of the present invention, « monodisperse » is understood to denote with reference to a series of droplets or a series of capsules, that the standard deviation of the distribution of the diameter of said droplets or said microcapsules is less than 50%, in particular less than 25%, or less than 1 μm. For the purposes of the present invention, the diameter of said droplets or said capsules is determined by light scattering technique using a Mastersizer 3000 (Malvern Instruments) equipped with a Hydro SV measurement cell.

[0064] In an advantageous aspect of the plurality of microcapsules according to the invention, the standard deviation of the distribution of the diameter D50vol of microcapsules is less than 10%, preferably equal to or less than 5%. Usually the standard deviation of the distribution of the diameter D50vol of microcapsules is greater than 1%, preferably equal to or greater than 3%.

[0065] This advantageous aspect allows in addition for a good control of the release of the active ingredient and more generally the activity of the plurality of microcapsules when applied, notably, in polymer manufacturing and processing applications.

[0066] In one aspect of the plurality of microcapsules according to  the invention, the microcapsules have a wall thickness from 0.1 to 40 μm, preferably from 0.8 to 30 μm.

[0067] In another aspect of the plurality of microcapsules according to  the invention, the microcapsules have an average diameter of from 1 to 30 μm and a wall thickness from 0.1 to 20 μm.

[0068] In another aspect of the plurality of microcapsules according to  the invention the microcapsules may have pores on the shell surface of the microcapsules which have an average diameter smaller than 1 nm, determined by BET surface analysis.

[0069] In still another aspect of the plurality of microcapsules according to  the invention, the crosslinked polymeric shell of the microcapsules may be suitably obtained by photopolymerization of a photopolymerizable composition having reactive groups. In this aspect, the conversion of reactive groups of the photopolymerizable composition is generally at least 80%, preferably at least 90%.

[0070] The conversion of reactive groups can be determined by the monitoring of the disappearance of one band representative of a functional group under FTIR, the absorption of IR bands being proportional to the amount of the functional group, therefore the reduction of peak height corresponds to the reduction of the amount of the functional group, further indicating successful polymerization. The standard method of doing this is comparison of the FTIR absorption of the polymer before and after cross-linking, in particular by photopolymerization. For the purpose of the present invention this can be done using the method disclosed in Barszczewska-Rybarek,Materials2019, 12(24), 4057. By way of example, the conversion of reactive acrylate groups over the course of radical polymerization can be observed as a function of the reduction in FTIR absorption of the signature spectrum thereof, for instance 1600 cm-1, 1407 cm-1or 810 cm-1.

[0071] In the homogeneous dispersion according to the invention, the polymeric shell of the microcapsules may be suitably obtained by polymerizing monomers and / or oligomers having a plurality of acrylate or methacrylate functionalities, in particular linear and / or branched poly(meth)acrylate monomers.

[0072] Often, the polymeric shell is obtained by polymerizing a composition comprising monomers and / or oligomers comprising at least catenary and / or annular heteroatoms. The heteroatoms are suitably selected from oxygen, nitrogen and sulphur.

[0073] In a particular aspect of the plurality of microcapsules according to the invention, the polymeric shell is obtained by polymerizing monomers and / or oligomers comprising at least an acrylated or methacrylated polyether monomer or oligomer.

[0074] The monomers and / or oligomers have preferably 2, 3, 4, 5 or 6 acrylate and / or methacrylate functionalities.

[0075] The average molecular weight of the monomers or oligomers having a plurality of acrylate or methacrylate functionalities used to produce the polymeric shell is generally from 300 to 1000 g / mole.

[0076] Preferred examples of polymers which can be used to produce the cross-linked shell include aliphatic epoxidized poly acrylates, e.g. soy bean oil acrylates, bisphenol A based epoxy acrylates, for example the product CN104D80 marketed by Sartomer glyceryl propoxy triacrylates, polyester acrylates or methacrylates, for example difunctional polyester acrylate oligomers, for example the product marketed as Photomer 5433 or Pureomer 5433 by IGM Resins, aliphatic polyester based urethane dimethacrylates or diacrylates and amine modified polyether acrylates.

[0077] In a particular aspect, the polymeric shell is obtained by polymerizing a composition further comprising monomers having a single acrylate or methacrylate functionality.

[0078] In that case, the average molecular weight of the monomers having a single acrylate or methacrylate functionality is usually lower than 300 g / mole.

[0079] Examples of monomers having a single acrylate functionality include terminal acrylates of saturated or unsaturated linear alcohols, in particular C8to C14saturated or unsaturated linear alcohols such as, for example, lauryl acrylate.

[0080] In this particular aspect, the weight ratio of the monomers or oligomers having a plurality of acrylate or methacrylate functionalities to the monomers having a single acrylate or methacrylate functionality is from 1 to 4 to 4 to 1 preferably from 1 to 2 to 2 to 1.

[0081] The polymeric shell of the microcapsules is generally obtained by polymerizing a composition further comprising a photoinitiator, preferably a photoinitiator for initiating the radical polymerization of acrylates and / or methacrylates.

[0082] In an advantageous aspect, the crosslinked polymeric shell of the microcapsules comprises at least 25 wt. %, preferably at least 30 wt. % of acrylate and / or methacrylate functionalities relative to the total weight of the crosslinked polymeric shell. In this advantageous aspect, the crosslinked polymeric shell comprises at most 60 wt. %, preferably at most 50 wt. % of acrylate and / or methacrylate functionalities relative to the total weight of the crosslinked polymeric shell.

[0083] The plurality of microcapsules according to the invention is obtainable, for example by a, preferably continuous, process which comprises (a) providing a double emulsion comprising droplets of at least one active ingredient (C1) dispersed in a polymerizable composition C2 comprising monomers and / or oligomers, in particular as described herein before, and a dispersant, said droplets being dispersed in a composition C3, the compositions C2 and C3 being immiscible with each other; (b) inducing a controlled shear rate in said double emulsion to provide a mixed double emulsion (C4) and (c) irradiating the mixed double emulsion (C4) such that the degree of conversion of polymerizable groups is at least 80%, preferably at least 90% to prepare the plurality of microcapsules. In a particular aspect, said polymerizable composition C2 may be photopolymerizable and contain at least 1% wt. preferably equal to or greater than 5% by weight relative to the total weight of composition C2 of a photoinitiator. The procedure for the preparation of the double emulsion is disclosed in particular in EP 3548529, US-A-2020129948 and US-A-2021113984 in the name of the applicant, the contents of which are incorporated by reference into the present patent application.

[0084] The different aspects of the invention described here before can be advantageously combined with each other.

[0085] The invention also concerns a second plurality of microcapsules having an active ingredient encapsulated in a cross-linked polymeric shell, having the same characteristics, as described herein above, as the plurality of microcapsules according to the invention, except that the cross-linked polymeric shell does not comprise a dispersant.

[0086] The invention also concerns a homogeneous dispersion comprising (a) a polymer matrix and (b) 0.1-15 % by weight, preferably 1-10% by weight relative to the total weight of the homogeneous dispersion of microcapsules dispersed therein, said microcapsules comprising an active ingredient encapsulated in a cross-linked polymeric shell.

[0087] Surprisingly , The homogeneous dispersion according to the invention presents a high degree of homogeneity and can be readily homogenized requiring a low mixing time. Dispersions according to the invention allow to obtain a good stability over time. A desirable notably a high concentration of active ingredient can be included in the homogeneous composition while maintaining adequate mechanical properties of the composition thereby allowing for efficient use in polymer production and processing. The polymer dispersions according to the invention allow for flexibility in terms of active ingredients. Both liquid and solid active ingredients can be efficiently encapsulated and dispersed in the polymer matrix. The active ingredient may be efficiently released into the matrix e.g. by heating. In that case a broad range of release temperature can be achieved and the active ingredient may be released over a narrow temperature interval, what is advantageous in terms of process control. The cross-linked microcapsules used in the present homogeneous dispersion remain substantially intact during the preparation of the dispersion.

[0088] For the purpose of the present invention, « homogeneous » is defined with reference to the microcapsules dispersed in the polymer matrix and designates the fact that the ratio of the D50dispmedian particle size of the microcapsules dispersed in the polymer matrix to the D50primarymedian particle size of the primary microcapsules in the absence of the polymer matrix is equal to or smaller than 2, preferably equal to or smaller than 1.5. More preferably this ratio is about 1. For sake of clarity, primary microcapsules refers to a sample consisting of microcapsules suitable for incorporation into the polymer matrix.

[0089] In particular for D50primarydiameter of the microcapsules between 20 and 80 microns, homogeneity may in addition be measured and defined through Hegmann Gauge analysis according to ISO 1524. In that case the homogeneity of the homogeneous dispersion according to the invention can be suitably expressed as normalized Hegmann value, defined as the ratio of the observed Hegmann diameter through the D50primarydiameter of the microcapsules. When this normalized Hegmann value is from 1 to 2, the dispersion is considered to be homogeneous.

[0090] The following general description of the homogeneous dispersion according to the invention applies to each particular aspect and to their combinations.

[0091] Generally, the homogeneous dispersion according to the invention remains stable for at least 2 hours, often for at least 24 hours, in certain aspects for at least 72 hours when stored at room temperature (25°C).

[0092] « Stable » is understood to denote a variation of the microscopy D50 ratio or of the normalized Hegmann value of less than 10 %.

[0093] In the homogeneous dispersion according to the invention, the polymer matrix often comprises or consists of at least one polymer selected from an isocyanate resin, an epoxy resin an acrylic resin, a vinyl resin and a polyester resin.

[0094] In one preferred aspect, the polymer matrix comprises or consists of an epoxy resin.

[0095] In another preferred aspect, the polymer matrix comprises or consists of an isocyanate resin.

[0096] In a particular, advantageous aspect, the homogeneous dispersion according to the invention is a premix for preparing a thermoset resin.

[0097] The homogeneous dispersion according to the invention generally contains from 85 wt. % to 99.9 wt %, preferably from 90 wt. % to 99 wt % relative to the total weight of the homogeneous dispersion of polymer matrix.

[0098] In a particular aspect, the content of microcapsules in the homogeneous dispersion according to the invention is equal to or greater than 2 % by weight, more particularly equal to or greater than about 5 % by weight relative to the total weight of the homogeneous dispersion. In this aspect the content of microcapsules in the homogeneous dispersion according to the invention may be about 10 % by weight, or equal to or smaller than 8 % by weight relative to the total weight of the homogeneous dispersion.

[0099] In one aspect, the homogeneous dispersion according to the invention further contains up to 10 wt. % relative to the total weight of the homogeneous dispersion of a polymer additive. Examples of adequate additives include but are not limited to fillers, pigments and blowing agents. In this aspect the homogeneous dispersion according to the invention generally contains from 75 wt. % to 89.9 wt %, preferably from 80 wt. % to 89 wt % relative to the total weight of the homogeneous dispersion of polymer matrix.

[0100] In a first particular aspect of the homogeneous dispersion according to the invention, the polymer matrix has a first topological polar surface area and the microcapsule shell has a second topological polar surface area as described above.

[0101] In this particular aspect, the first topological polar surface area is often equal to or greater than 30 Ų preferably equal to or greater than 35 Ų. In this particular aspect, the first topological polar surface area is often equal to or lower than 60 Ų preferably equal to or lower than 50 Ų.

[0102] In an advantageous aspect of the homogeneous dispersion according to the invention, the polymer matrix and the microcapsules are selected such that the difference between the first topological polar surface area and the second topological polar surface area is equal to or lower than 40 Ų, preferably equal to or lower than 30 Ų.

[0103] In a second particular aspect of the homogeneous dispersion according to the invention, the ratio of the bulk density of the microcapsules to the bulk density of the matrix is often from 0.8 to 1.2, preferably from 0.9 to 1.1. The bulk density according to this aspect may be determined by gas pycnometry using helium.

[0104] The second aspect of the homogeneous dispersion according to the invention allows in particular to obtain homogeneous dispersions which are stable during storage and / or can be readily redispersed, if necessary.

[0105] Preferably, the homogeneous dispersion according to the invention comprises the microcapsules according to the invention. Other microcapsules having the same characteristics as described above for the plurality of microcapsules according to the invention except for the absence in such other microcapsules of a dispersant can also be used in the homogeneous dispersion according to the invention.

[0106] The invention also concerns a process for producing the homogeneous dispersion according to the invention, which comprises mixing the polymer matrix and 0.1-15 % by weight, preferably 1-10% by weight relative to the total weight of the homogeneous dispersion to be produced of microcapsules for a time sufficient to produce the homogeneous dispersion.

[0107] In the process according to the invention, the homogeneous dispersion is often produced within less than15 minutes, preferably within less than 5 minutes.

[0108] The invention also concerns a process for producing a polymeric article which comprises using the homogeneous dispersion according to the invention.

[0109] The examples here after are intended to illustrate the invention without however limiting it :

[0110] EXAMPLES

[0111] Examples 1 and 2

[0112] Tables 1 and 2 list the starting Materials used in examples 1 and 2. In these examples the active ingredient is a solid at 25°C.

[0113] Example 1: A second plurality of microcapsules (without dispersant in the shell)Ratio in each phaseRatio in D1Ratio in D2Dispersion 1Active ingredient(Composition C1)DYHard UR400, Alzchem100%40%10%Shell (Composition C2)Photomer 5433, IGM Resins55%60%Lauryl acrylate44,50%Ethyl (2,4,6-trimethylbenzoyl) phenyl phosphinate)0,50%Continuous phase (Composition C3)CarboxyMethyl Cellulose8,00%90%Non-newtonian viscosifying agent0,10%Lignosulfonates0,10%Water91,80%

[0114] Example 2: Plurality of microcapsules with 4 % dispersant in the shellRatio in each phaseRatio in D1Ratio in D2D1Active ingredient(Composition C1)DYHard UR400, Alzchem100%40%10%Shell (Composition C2)(Photomer 5433, IGM Resins)53%60%Lauryl acrylate42,70%Ethyl (2,4,6-trimethylbenzoyl) phenyl phosphinate)0,48%Disperbyk 20-30, Byk additives4,00%Continuous phase (Composition C3)CarboxyMethyl Cellulose8,00%90%Non-newtonian viscosifying agent0,10%Lignosulfonates0,10%Water91,80%

[0115] Preparation of the plurality of microcapsules according to examples 1 and 2

[0116] Step a): Composition C1

[0117] In the following example, the core of the capsules is the active ingredient which is a urea derivative latent curing agent for epoxy resins having an average particle size (D50) of 2,9 µm.

[0118] Step b): Preparation of the shell composition Composition C2:

[0119] The shell composition of the capsule is prepared by mixing the starting compounds, as shown in the tables 1 and 2 respectively, and in example 2 a dispersant, in the proportions shown in the tables 1 and 2 respectively at room temperature until the composition is homogeneous, thereby obtaining C2.

[0120] Step c): Preparation of the first dispersion (D1)

[0121] The composition of the core C1 is added at room temperature to the composition of the shell C2 with a mixing rate of 2000 rpm to produce a first dispersion D1. The ratio of the weight of the shell to the weight of the core is 60 / 40.

[0122] Step d): Preparation of the Second dispersion (D2):

[0123] Composition C3, the continuous phase, is produced from cellulose derivative, non-newtonian rheology modifiers and water. The composition C3 is stirred at 3,050 rpm until complete homogenization for concentration between 6 % and 10 %. The first dispersion D1 is then added to the composition C3, which is then stirred at 2,000 rpm for 2 minutes at RT to obtain the second dispersion D2, at a ratio of D1:C3 of 10:90.

[0124] Step d): Reticulation of the Capsule Envelope:

[0125] The second dispersion (D2) obtained in the previous step is irradiated for 2 minutes with the aid of a UV light source at a wavelength of 365 nm.

[0126] The microcapsules were separated from their continuous phase by centrifugation at 2500 G for over 3 cycles for a total of 20 min.Examples 3 & 4

[0127] Tables 3 and 4 list the starting Materials used in examples 3 and 4. In these examples the active ingredient is a solid at 25°C .

[0128] Example 3: Without dispersant in the shellRatio in each phaseRatio in D1Ratio in D2Dispersion 1Active ingredient(Composition C1)Ancamine 2014-FG, Evonik100%40%10%Shell (Composition C2)CN104D80, Sartomer60%60%Isobornyl acrylate35%Ethyl (2,4,6-trimethylbenzoyl) phenyl phosphinate)5 %Continuous phase (Composition C3)CarboxyMethyl Cellulose8,00%90%Non-newtonian viscosifying agent0,10%Lignosulfonates0,10%Water91,80%

[0129] Example 4: With 4 % dispersant in the shellRatio in each phaseRatio in D1Ratio in D2D1Active ingredient(Composition C1)Ancamine 2014-FG, Evonik100%40%10%Shell (Composition C2)CN104D80, Sartomer57,6 %60%Isobornyl acrylate33,6 %Ethyl (2,4,6-trimethylbenzoyl) phenyl phosphinate)4, 8 %Disperbyk 20-30, Byk additives4,00%Continuous phase (Composition C3)CarboxyMethyl Cellulose8,00%90%Non-newtonian viscosifying agent0,10%Lignosulfonates0,10%Water91,80%

[0130] Preparation of the plurality of microcapsules according to examples 3 and 4

[0131] Step a): Composition C1

[0132] In the following example, the core of the capsules is the active ingredient which is a polyamine curing agent for epoxy resins having an average particle size (D50) of 3,2 µm.

[0133] Step b): Preparation of the shell composition Composition C2:

[0134] The shell composition of the capsule is prepared by mixing the starting compounds, as shown in the tables 3 and 4 respectively, and in example 4 a dispersant, in the proportions shown in the tables 3 and 4 respectively at room temperature until the composition is homogeneous, thereby obtaining C2.

[0135] Step c): Preparation of the first dispersion (D1)

[0136] The composition of the core C1 is added at RT to the composition of the shell C2 with a mixing rate of 2000 rpm to produce a first dispersion D1. The ratio of the weight of the shell to the weight of the core is 60 / 40.

[0137] Step d): Preparation of the Second dispersion (D2):

[0138] Composition C3, the continuous phase, is produced from cellulose derivative, non-newtonian rheology modifiers and water. The composition C3 is stirred at 3,050 rpm until complete homogenization for concentration between 6 % and 10 %. The first dispersion D1 is then added to the composition C3, which is then stirred at 2,000 rpm for 2 minutes at RT to obtain the second dispersion D2, at a ratio of D1:C3 of 10:90.

[0139] Step d): Reticulation of the Capsule Envelope:

[0140] The second dispersion (D2) obtained in the previous step is irradiated for 2 minutes with the aid of a UV light source at a wavelength of 365 nm.

[0141] The microcapsules were separated from their continuous phase by centrifugation at 2500 G for over 3 cycles for a total of 20 min.Examples 5 & 6

[0142] Tables 5 and 6 list the starting Materials used in examples 5 and 6. In these examples the actives ingredient is a solid at 25°C

[0143] Example 5: Without dispersant in the shellRatio in each phaseRatio in D1Ratio in D2Dispersion 1Active ingredient(Composition C1)Curezol 2PZ, Evonik100%40%10%Shell (Composition C2)CN104D80, Sartomer75%60%Isobornyl methacrylate20%Ethyl (2,4,6-trimethylbenzoyl) phenyl phosphinate)5%Continuous phase (Composition C3)CarboxyMethyl Cellulose8,00%90%Non-newtonian viscosifying agent0,10%Lignosulfonates0,10%Water91,80%

[0144] Example 6: With 4 % dispersant in the shellRatio in each phaseRatio in D1Ratio in D2D1Active ingredient(Composition C1)Curezol 2PZ, Evonik100%40%10%Shell (Composition C2)CN104D80, Sartomer)77,29%60%Isobornyl methacrylate20,61%Ethyl (2,4,6-trimethylbenzoyl) phenyl phosphinate)0,48%Disperbyk 20-30, Byk additives)2 %Continuous phase (Composition C3)CarboxyMethyl Cellulose8,00%90%Non-newtonian viscosifying agent0,10%Lignosulfonates0,10%Water91,80%

[0145] Preparation of the plurality of microcapsules according to examples 5 and 6

[0146] Step a): Composition C1

[0147] In the following example, the core of the capsules is the active ingredient which is an imidazole curing agent for epoxy resins having an average particle size (D50) of 20,8 µm..

[0148] Step b): Preparation of the shell composition Composition C2:

[0149] The shell composition of the capsule is prepared by mixing the starting compounds, as shown in the tables 5 and 6 respectively, and in example 5 a dispersant, in the proportions shown in the tables 5 and 6 respectively at room temperature until the composition is homogeneous, thereby obtaining C2.

[0150] Step c): Preparation of the first dispersion (D1)

[0151] The composition of the core C1 is added at RT to the composition of the shell C2 with a mixing rate of 2000 rpm to produce a first dispersion D1. To improve the dispersion, the dispersion D1 is further mixed through a three roll mill Exakt E80 from Exakt Technologies. The enter gap between the first and the second rolls is 10 µm whereas the exit gap between the second and the third rolls is 5 µm. The dispersion D1 is mixed three times with Exakt E80, the rolls having a speed of 150 rpm. The ratio of the weight of the shell to the weight of the core is 60 / 40.

[0152] Step d): Preparation of the Second dispersion (D2):

[0153] Composition C3, the continuous phase, is produced from cellulose derivative, non-newtonian rheology modifiers and water. The composition C3 is stirred at 2,000 rpm until complete homogenization for concentration between 6 % and 10 %. The first dispersion D1 is then added to the composition C3, which is then stirred at 2,000 rpm for 2 minutes at RT to obtain the second dispersion D2, at a ratio of D1:C3 of 10:90.

[0154] Step d): Reticulation of the Capsule Envelope:

[0155] The second dispersion (D2) obtained in the previous step is irradiated for 2 minutes with the aid of a UV light at a wavef length of 365 nm.

[0156] The microcapsules were separated from their continuous phase by centrifugation at 2000 G for over 3 cycles for a total of 20 min.

[0157] Evaluation: viscosity of dispersions D1 involved in examples 1 to 6Protocol

[0158] Viscosity of the dispersions D1 is measured with an Anton Paar Rheometer MCR702.

[0159] The measurement is carried out using a flat cone geometry for an air gap of 0.3 mm. The D1 dispersion is, at first, sheared at 100 s-1for 1 min. The measurement is performed by performing a shear scan in shear from 0.1 s-1to 100 s-1at 20 °C.

[0160] Table 7 shows the viscosity values obtained for the dispersion D1 in examples 1 to 4

[0161] Viscosity of D1 at 10 s-1at 20°C (mPa.s)Example 119551.76Example 25334.50Example 388783Example 453519

[0162] In both series of examples, the viscosity of the dispersion D1 is significantly reduced through the addition of a dispersant in the shell.

[0163] Evaluation: particle size distribution of microcapsules in the plurality of microcapsules

[0164] The particle size by volume of the microcapsules is measured with a Mastersizer 3000 equipped with a hydro SV measuring cell. 1 mL of microcapsules slurry is diluted in 200 mL to perform the measurement. Results are shown in Table 8.

[0165] Example‍RepeatDv(10) (µm)Dv(50) (µm)Dv(90) (µm)Example 5 (without dispersant)‍Run 13,8511,1058Run 2‍6,6520,971Example 6- (with 2 % dispersant)‍Run 16,2018,2062,60‍Run 26,491961,10

[0166] In both series of examples, the addition of a dispersant (examples 4 and 6) enabled to improve the repeatability in the microcapsules fabrication by reducing the distribution in size between each repeat.

[0167] Bulk density is determined using the method Gas Pycnometry for Semi-Solid and Solid Density, with the device Anton Paar Ultrapyc 5000, measured at a pressure of 0.69 bar using helium.

[0168] Step a): Composition C1In the following example, the core of the capsules is the active ingredient which is an amine latent curing agent for epoxy resins.

[0169] Step b): Preparation of the shell composition Composition C2: The shell composition of the capsule is prepared by mixing 55 % wt.of an oligomer obtained by reaction of C18 unsaturated fatty acid dimers with acrylic acid and 1,3,5-tris(2-hydroxyethyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, having 4 acrylate functionalities with 44,5 % wt. lauryl acrylate and 0,5 % of photoinitiator at RT until homogeneous, thereby obtaining C2.

[0170] The composition of the core C1 is added at RT to the composition of the shell C2 with a mixing rate of 100 rpm to produce a first emulsion E1. The ratio of the weight of the shell to the weight of the core is 60 / 40.

[0171] Step c): Preparation of the Second Emulsion (E2): Composition C3, the continuous phase, is produced from cellulose derivative, and water. The composition C3 is stirred at 2,000 rpm until complete homogenization for concentration between 6 % and 10 %. The first emulsion E1 is then added to the composition C3, which is then stirred at 2,000 rpm for 2 minutes at RT to obtain the second emulsion E2, at a ratio of E1:C3 of 10:90.

[0172] Step d): Reticulation of the Capsule Envelope: The second emulsion (E2) obtained in the previous step is irradiated for 2 minutes with the aid of UV light at a wave length of 365 nm. The microcapsules were separated from their continuous phase by centrifugation at 2000 G for over 3 cycles for a total of 20 min.

[0173] The properties of the microcapsules were as follows D50 47.2 μmTopological polar surface area 72.08 ŲBulk density 1,1612

[0174] Example 8 – Production and testing of the homogeneous dispersion according to the invention

[0175] a)- Preparation of the microcapsule dispersion: As polymer matrix, the epoxy resin DER 332 CAS 1675-54-3 was used.

[0176] The properties of the matrix were as follows :Topological polar surface area 72.08 ŲBulk density 1,16In a beaker, DER 332, is mixed with microcapsules of example 7, using a mechanical stirrer (Ika Eurostar 20) equipped with a deflocculating stirring propeller for a concentration of microcapsules of 10 wt % at a speed of 2,000 rpm for 5 min.

[0177] b – Homogeneity test with Hegmann gauge: After mixing the dispersion during the appropriate time, two times of 0,5 mL – 1 mL of dispersion are deposited in the two slots of the Hegmann gauge. The normalized Hegmann value was 1.1, indicating a homogeneous dispersion.

[0178] The Hegmann gauge experiment is repeated after 3 days storage of the homogeneous dispersion at room temperature. The normalized Hegmann value is substantially unchanged.

Claims

A plurality of microcapsules comprising an active ingredient encapsulated in a cross-linked polymeric shell, wherein the crosslinked polymeric shell comprises a dispersant.The plurality of microcapsules according to claim 1, wherein the dispersant is selected from the group consisting of dispersants having a polar end- group in particular those capable of binding to pigments, lignosulphonates and cationic polyacrylates.The plurality of microcapsules according to claim 1 or 2, wherein the dispersant is DISPERBYK (R) 2030.The plurality of microcapsules according to anyone of claims 1 to 3, wherein the content of dispersant is from 1 wt.% to 5 wt.%, preferably from 2 wt.% to 4 wt.%relative to the total weight of the cross-linked polymeric shell.The plurality of microcapsules according to anyone of claims 1 to 4, wherein the topological polar surface area of the microcapsule shell is from 60 to 90 Ų, preferably from 65 to 75 Ų.The plurality of microcapsules according to anyone of claims 1 to 5, wherein the D50 of the microcapsules is from 20 to 80 microns.The plurality of microcapsules according to  any of the preceding claims  wherein the cross-linked polymeric shell has a cross-linking density of 0.5 to 4 mmole / g, preferably from 0.7 to 1.5 mmole / g.The plurality of microcapsules according to any of the preceding claims, wherein the active ingredient is selected from a catalyst, a UV absorber, a lubricant and a flame retardant, a pigment, an agrochemical product, a liquid crystal material, a curing agent and a latent accelerator of curing of an epoxy resin.The plurality of microcapsules according to claim 8 wherein the active ingredient is a latent accelerator of curing of an epoxy resin selected from amine latent accelerators, in particular polyamine latent accelerators.The plurality of microcapsules according to any of the preceding claims, wherein the active ingredient is a solid at 25°C.The plurality of microcapsules according to any of the preceding claims, wherein the active ingredient is a liquid at 25°C at a pressure of 1013,25 kPa.The plurality of microcapsules according to any of the preceding claims, wherein the polymeric shell is obtained by polymerizing a composition comprising monomers and / or oligomers comprising monomers or oligomers having a plurality of acrylate or methacrylate functionalities, in particular linear and / or branched poly(meth)acrylate monomers.The plurality of microcapsules according to any of the preceding claims, wherein the polymeric shell is obtained by polymerizing a composition comprising monomers and / or oligomers comprising at least catenary and / or annular heteroatoms.The plurality of microcapsules according to claim 13, wherein the heteroatoms are selected from oxygen, nitrogen and sulphur.The plurality of microcapsules according to claim 13 or 14, wherein the polymeric shell is obtained by polymerizing a composition comprising monomers and / or oligomers comprising at least an acrylated polyether monomer or oligomer.The plurality of microcapsules according to anyone of claims 12 to 15 wherein the monomers and / or oligomers have 2, 3, 4, 5 or 6 acrylate or methacrylate functionalities.The plurality of microcapsules according to anyone of claims 12 to 16 wherein the average molecular weight of the monomers or oligomers having a plurality of acrylate or methacrylate functionalities is from 300 to 1000 g / moleThe plurality of microcapsules to anyone of claims 12 to 17 wherein the polymeric shell is obtained by polymerizing a composition further comprising monomers having a single acrylate or methacrylate functionality.The plurality of microcapsules according to claim 18 wherein the average molecular weight of the monomers having a single acrylate or methacrylate functionality is lower than 300 g / mole.The plurality of microcapsules according to claim 18 or 19 wherein the weight ratio of the monomers or oligomers having a plurality of acrylate or methacrylate functionalities to the monomers having a single acrylate or methacrylate functionality is from 1 to 4 to 4 to 1 preferably from 1 to 2 to 2 to 1.The plurality of microcapsules according to anyone of claims 12 to 20 wherein the polymeric shell is obtained by polymerizing a composition further comprising a photoinitiator, preferably a photoinitiator for initiating the radical polymerization of acrylates and / or methacrylates.The plurality of microcapsules according to any of the preceding claims wherein the crosslinked polymeric shell comprises at least 25 wt. %, preferably at least 30 wt. % of acrylate and / or methacrylate functionalities relative to the total weight of the crosslinked polymeric shell.The plurality of microcapsules according to any of the preceding claims wherein the crosslinked polymeric shell comprises at most 60 wt. %, preferably at most 50 wt. % of acrylate and / or methacrylate functionalities relative to the total weight of the crosslinked polymeric shell.The plurality of microcapsules according to any of the preceding claims wherein the microcapsules are monodisperse.The plurality of microcapsules according to claim 24 wherein the standard deviation of the distribution of the diameter of microcapsules is less than 50%, or less than 1 μm.The plurality of microcapsules according to claim 25 wherein the standard deviation of the distribution of the diameter D50vol of microcapsules is less than 10%, preferably equal to or less than 5%.The plurality of microcapsules according to any of the preceding claims wherein the microcapsules have a wall thickness from 0.1 to 40 μm, preferably from 0.8 to 30 μm.The plurality of microcapsules according to any of the preceding claims wherein the microcapsules have an average diameter of from 1 to 30 μm and a wall thickness from 0.1 to 20 μm.The plurality of microcapsules according to any of the preceding claims wherein the pores on the shell surface of the said microcapsules have an average diameter smaller than 1nm, determined by BET surface analysis. The plurality of microcapsules according to any of the preceding claims, wherein the crosslinked polymeric shell of the microcapsules is obtained by polymerization, in particular photopolymerization of a polymerizable composition C2 comprising at least monomers having reactive groups, a dispersant and, if appropriate a photoinitiator.The plurality of microcapsules according to claim 31, wherein the conversion of reactive groups of the photopolymerizable composition C2 is at least 80%, preferably at least 90%.The plurality of microcapsules according to any of the preceding claims, wherein the dispersant is homogeneously distributed in the cross-linked polymeric shell.The plurality of microcapsules according to any of the preceding claims, wherein the dispersant is covalently bonded to the cross-linked polymeric shell.The plurality of microcapsules according to claim 31, wherein the dispersant can form a copolymer with at least one other components of the crosslinked polymeric shell, and is suitably selected from an acrylate group containing dispersant, for example a polyacrylate dispersant which can be copolymerized with (meth)acrylate monomers and / or oligomers , in particular in accordance with anyone of claims 11 to 23, to form the cross-linked polymeric shell.A homogeneous dispersion comprising (a) a polymer matrix and (b) 0.1-15 % by weight, preferably 1-10% by weight relative to the total weight of the homogeneous dispersion of the plurality of microcapsules according to anyone of the preceding claims dispersed therein.The homogeneous dispersion according to claim 33 wherein the polymer matrix comprises or consists of at least one polymer selected from an isocyanate resin, an epoxy resin an acrylic resin, a vinyl resin and a polyester resin.A process for producing a polymeric article or product, which comprises using the plurality of microcapsules according to any of claims 1 to 34.A process for producing the plurality of microcapsules according to any of claims 1 to 34 which comprises (a) providing a double emulsion comprising droplets of at least one active ingredient (C1) dispersed in a polymerizable composition C2 comprising monomers and / or oligomers, in particular as described herein before, and a dispersant, said droplets being dispersed in a composition C3, the compositions C2 and C3 being immiscible with each other; (b) inducing a controlled shear rate in said double emulsion to provide a mixed double emulsion (C4) and (c) irradiating the mixed double emulsion (C4) such that the degree of conversion of polymerizable groups is at least 80%, preferably at least 90% to prepare the plurality of microcapsules.A plurality of microcapsules which is in accordance with anyone of claims 5 to 31, except that no dispersant is present in the cross-linked polymeric shell.