FIELD OF THE DISCLOSURE

The disclosure relates to capsules and methods of making capsules for the transfer and triggered release of benefit agents.

BACKGROUND

Microencapsulation is a process where droplets of liquids, particles of solids or gasses are enclosed inside a solid shell and are generally in the micro-size range. The core material is then mechanically separated from the surrounding environment (Jyothi et al.,Journal of Microencapsulation,2010, 27, 187-197). Microencapsulation technology is attracting attention from various fields of science and has a wide range of commercial applications for different industries. Overall, capsules are capable of one or more of (i) providing stability of a formulation or material via the mechanical separation of incompatible components, (ii) protecting the core material from the surrounding environment, (iii) masking or hiding an undesirable attribute of an active ingredient and (iv) controlling or triggering the release of the active ingredient to a specific time or location. All of these attributes can lead to an increase of the shelf-life of several products and a stabilization of the active ingredient in liquid formulations.

Encapsulation can be found in areas such as pharmaceuticals, personal care, textiles, food, coatings and agriculture. In addition, the main challenge faced by microencapsulation technologies in real-world commercial applications is that a complete retention of the encapsulated active within the capsule is required throughout the whole supply chain, until a controlled or triggered release of the core material is applied (Thompson et al.,Journal of Colloid and Interface Science,2015, 447, 217-228). There are significantly limited microencapsulation technologies that are safe for both the environment and human health with a long-term retention and active protection capability that can fulfill the needs of the industry nowadays, especially when it comes to encapsulation of small molecules.

Over the past several years, consumer goods manufacturers have used core-shell encapsulation techniques to preserve actives, such as benefit agents, in harsh environments and to release them at the desired time, which may be during or after use of the consumer goods. Among the several mechanisms that can be used for release of benefit agent, the one commonly relied upon is mechanical rupture of the capsule shell. Selection of mechanical rupture as the release mechanism constitutes another challenge to the manufacturer, as rupture must occur at specific desired times, even if the capsules are subject to mechanical stress prior to the desired release time.

Industrial interest for encapsulation technology has led to the development of several polymeric capsules chemistries which attempt to meet the requirements of low shell permeability, high deposition, targeted mechanical properties and rupture profile. Increased environmental concerns have put the polymeric capsules under scrutiny, therefore manufacturers have started investigating sustainable solutions for the encapsulation of benefit agents. There is ample literature on sustainable capsules based on metal oxide or semi-metal oxides, mainly silica capsules; however, none of the capsules described in the literature provides the right balance of low shell permeability, mechanical properties, deposition, and rupture profile.

Capsules made with silane monomers only are known in the art. Multiple patent applications and academic publications disclose the use of monomers such as tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS). The advantage of using such monomers is that they react faster than prepolymers made from similar monomers, and as such have been the favored option for years. This fast reaction time is due to their higher water solubility once partially hydrolyzed compared to larger precursors, due to the fact that the former have lower molecular weights, which accelerate further the overall hydrolysis kinetics as they are in an excess of water once dispersed in said phase. However, these types of disclosures often use cationic surfactants such as cetyltrimethylammonium chloride (CTAC) or cetyltrimethylammonium bromide (CTAB), supposedly to drive the negatively charged hydrolyzed intermediate reaction species that are dispersed in the water phase towards the oil/water interface.

Without wishing to be bound by theory, what is often the case is that the partially hydrolyzed monomers that are in an excess of water start condensing and forming ever larger particulate sols that are drawn to oil/water interfaces. Ultimately, the system desires to reduce surface energies of dispersed particulate sols by virtue of thermodynamic laws, which favors having the sols at the oil/water interfaces, especially when they grow large. The formation of such particulate sols can eventually lead to a shell around oil droplets and in some cases even shells that are strong enough towards mechanical self-integrity. However, by virtue of the geometrical properties (size, fractal dimensions, shapes etc.) of particulate sols, they are not able to form shells with a dense non-porous network that would provide low shell permeability.

In addition, WO 2011/131644 discloses capsules with a semi-metal organic shell by joining together nanoparticles with the use of an oil soluble semi-metal precursor. However, the reference does not disclose a second shell component. In the present invention it has been found that a selective choice of nanoparticles and precursors coupled with a second shell component provides capsules that have reduced permeability and increased mechanical integrity.

Without wishing to be bound by theory, the applicant has surprisingly found that a careful selection of primary shell components, secondary shell components, nanoparticles, core-shell ratio, and thickness of the shell allows production of metal oxide or semi-metal oxide based capsules which hold their mechanical integrity once left air-drying on a surface and have low shell permeability in surfactant-based matrices. These two properties are the desired results but are also characteristics of a dense and strong shell with low permeability made possible only by the judicious choice of component materials and conditions to assemble them.

SUMMARY

There is a need for an encapsulation technique that is both low toxicity and ecologically safe as an alternative to traditional synthetic chemicals. A methodology to encapsulate benefit agents via a green emulsification technique and sustainable materials in the shell is desired.

In accordance with embodiments, a population of capsules is provided wherein the capsules can include an oil-based core and a shell surrounding the core. In embodiments, the oil-based core can include a benefit agent. In embodiments, the shell can include a first shell component and a second shell component, wherein the second shell component is surrounding the first shell component. In embodiments, the first shell component can include a condensed layer and a nanoparticle layer, wherein the condensed layer is disposed between the core and the nanoparticle layer. In embodiments, the condensed layer can include a condensation product of a precursor. In embodiments, the second shell component can include an inorganic coating, wherein the inorganic coating surrounds the nanoparticle layer. In embodiments, the precursor comprises at least one compound of Formula (I): (MvOzYn)w(Formula I), where M is one or more of silicon, titanium and aluminum, v is the valence number of M and is 3 or 4, z is from 0.5 to 1.6, preferably 0.5 to 1.5, each Y is independently selected from —OH, —OR2, halo,


—NH2, —NHR2, —N(R2)2, and


wherein R2is a C1to C20alkyl, C1to C20alkylene, C6to C22aryl, or a 5-12 membered heteroaryl comprising from 1 to 3 ring heteroatoms selected from O, N, and S, R3is a H, C1to C20alkyl, C1to C20alkylene, C6to C22aryl, or a 5-12 membered heteroaryl comprising from 1 to 3 ring heteroatoms selected from O, N, and S, n is from 0.7 to (v−1), and w is from 2 to 2000.

In accordance with embodiments, a population of capsules is provided wherein the capsules can include an aqueous core and a shell surrounding the core. In embodiments, the aqueous core can include a benefit agent. In embodiments, the shell can include a first shell component. In embodiments, the first shell component can include a condensed layer and a nanoparticle layer. In embodiments, the condensed layer can include a condensation product of a precursor. In embodiments, the precursor comprises at least one compound of Formula (I): (MvOzYn)w(Formula I), where M is one or more of silicon, titanium and aluminum, v is the valence number of M and is 3 or 4, z is from 0.5 to 1.6, preferably 0.5 to 1.5, each Y is independently selected from —OH, —OR2, halo,


—NH2, —NHR2, —N(R2)2, and


wherein R2is a C1to C20alkyl, C1to C20alkylene, C6to C22aryl, or a 5-12 membered heteroaryl comprising from 1 to 3 ring heteroatoms selected from O, N, and S, R3is a H, C1to C20alkyl, C1to C20alkylene, C6to C22aryl, or a 5-12 membered heteroaryl comprising from 1 to 3 ring heteroatoms selected from O, N, and S, n is from 0.7 to (v−1), and w is from 2 to 2000.

In accordance with embodiments, a population of capsules is provided wherein the capsules can include an aqueous core and a shell surrounding the core. In embodiments, the aqueous core can include a benefit agent. In embodiments, the shell can include a first shell component. In embodiments, the first shell component can include a condensed layer and a nanoparticle layer. In embodiments, the condensed layer can include a condensation product of a precursor. In embodiments, the precursor comprises at least one compound of Formula (I) or Formula (II): (MvOzYn)w(Formula I), where M is one or more of silicon, titanium and aluminum, v is the valence number of M and is 3 or 4, z is from 0.5 to 1.6, preferably 0.5 to 1.5, each Y is independently selected from —OH, —OR2, halo,


—NH2, —NHR2, —N(R2)2, and


wherein R2is a C1to C20alkyl, C1to C20alkylene, C6to C22aryl, or a 5-12 membered heteroaryl comprising from 1 to 3 ring heteroatoms selected from O, N, and S, R3is a H, C1to C20alkyl, C1to C20alkylene, C6to C22aryl, or a 5-12 membered heteroaryl comprising from 1 to 3 ring heteroatoms selected from O, N, and S, n is from 0.7 to (v−1), and w is from 2 to 2000; (MvOzYnR1p)w(Formula II), where M is one or more of silicon, titanium and aluminum, v is the valence number of M and is 3 or 4, z is from 0.5 to 1.6, preferably 0.5 to 1.5, each Y is independently selected from —OH, —OR2, halo, —NH2, —NHR2, —N(R2)2, and, wherein R2is a C1to C20alkyl, C1to C20alkylene, C6to C22aryl, or a 5-12 membered heteroaryl comprising from 1 to 3 ring heteroatoms selected from O, N, and S, R3is a H, C1to C20alkyl, C1to C20alkylene, C6to C22aryl, or a 5-12 membered heteroaryl comprising from 1 to 3 ring heteroatoms selected from O, N, and S, n is from 0 to (v−1), each R1is independently selected from a C1to C30alkyl, a C1to C30alkylene, a C1to C30alkyl substituted with one or more of a halogen, —OCF3, —NO2, —CN, —NC, —OH, —OCN, —NCO, alkoxy, epoxy, amino, mercapto, acryloyl, CO2H, CO2alkyl, aryl, and heteroaryl, and a C1to C30alkylene substituted with one or more of a halogen, —OCF3, —NO2, —CN, —NC, —OH, —OCN, —NCO, alkoxy, epoxy, amino, mercapto, acryloyl, CO2H, CO2alkyl, aryl, and heteroaryl, p is present in an amount up to pmax, and w is from 2 to 2000.

In accordance with embodiments, a population of capsules is provided wherein the capsules can include an aqueous core and a shell surrounding the core. In embodiments, the aqueous core can include a benefit agent. In embodiments, the shell can include a first shell component. In embodiments, the first shell component can include a condensed layer and a nanoparticle layer. In embodiments, the condensed layer can include a condensation product of a precursor. In embodiments, the precursor comprises at least one compound of Formula (II): (MvOzYnR1p)w(Formula II), where M is one or more of silicon, titanium and aluminum, v is the valence number of M and is 3 or 4, z is from 0.5 to 1.6, preferably 0.5 to 1.5, each Y is independently selected from —OH, —OR2, halo, —NH2, —NHR2, —N(R2)2, and, wherein R2is a C1to C20alkyl, C1to C20alkylene, C6to C22aryl, or a 5-12 membered heteroaryl comprising from 1 to 3 ring heteroatoms selected from O, N, and S, R3is a H, C1to C20alkyl, C1to C20alkylene, C6to C22aryl, or a 5-12 membered heteroaryl comprising from 1 to 3 ring heteroatoms selected from O, N, and S, n is from 0 to (v−1), each R1is independently selected from a C1to C30alkyl, a C1to C30alkylene, a C1to C30alkyl substituted with one or more of a halogen, —OCF3, —NO2, —CN, —NC, —OH, —OCN, —NCO, alkoxy, epoxy, amino, mercapto, acryloyl, CO2H, CO2alkyl, aryl, and heteroaryl, and a C1to C30alkylene substituted with one or more of a halogen, —OCF3, —NO2, —CN, —NC, —OH, —OCN, —NCO, alkoxy, epoxy, amino, mercapto, acryloyl, CO2H, CO2alkyl, aryl, and heteroaryl, p is present in an amount up to pmax, and w is from 2 to 2000.

