Hydrophilic liquid encapsulates
A process of forming a population of microcapsules is described comprising a liquid hydrophilic core material and a wall material at least partially surrounding the core material. The liquid hydrophilic core material can be anionic, cationic, or neutral but polar. The microcapsule population is formed by providing liquid hydrophilic core material; providing an oil continuous phase which is low boiling and preferably nonflammable, the oil continuous phase comprising preferably one or more organic oil materials such as esters with chain length up to about 42 carbons. A mixture is formed by dispersing the liquid hydrophilic material in the oil continuous phase. Either an oil soluble or dispersible monofunctional amine acrylate or monofunctional amine methacrylate, along with acid; or alternatively monofunctional acid acrylate or monofunctional acid methacrylate along with base; or alternatively, monofunctional amine acrylate or monofunctional amine methacrylate along with acid acrylate or methacrylate; is added. A multifunctional acrylate or methacrylate monomer or oligomer is provided along with an initiator. Optionally a surfactant is also added to form the mixture. Emulsification is achieved by subjecting the mixture to high shear agitation and heating the mixture for a time sufficient to enable forming a prepolymer which migrates to the liquid hydrophilic material, thereby forming prepolymers adhered to the hydrophilic core materials. Heating is carried out or light exposure or both for a time and temperature sufficient to crosslink the prepolymers.
1. A process for forming a population of microcapsules comprising a liquid hydrophilic core material and a wall material at least partially surrounding the core material, the microcapsule population being formed by:
providing a hydrophilic liquid core material;
providing an oil continuous phase which is low boiling and preferably nonflammable, the oil continuous phase comprising one or more of an organic oil material with chain length up to about 42 carbons;
dividing the oil continuous phase into oil 1 and oil 2;
dispersing into oil 1 an initiator;
dispersing into oil 2 a multifunctional acrylate or methacrylate monomer or oligomer, and an oil soluble or dispersible monofunctional amine acrylate or monofunctional amine methacrylate, and an acid;
combining oil 1 and oil 2;
forming a mixture by dispersing the liquid hydrophilic material into the oil continuous phase;
optionally adding a surfactant;
emulsifying the mixture by subjecting the mixture to high shear agitation;
heating the mixture for a time sufficient to enable the monofunctional amine acrylate or monofunctional amine methacrylate and the multifunctional acrylate or methacrylate to form a cationic prepolymer which migrates to the liquid hydrophilic material, thereby forming prepolymers adhered to and surrounding the hydrophilic core material, wherein the acid and monofunctional amine acrylate or monofunctional amine methacrylate have a molar proportion of from 3:1 to 1:3.
2. The process of forming a population of microcapsules according to claim 1 wherein the acid and monofunctional amine acrylate or monofunctional amine methacrylate have a percent by weight as compared to weight of the wall material of from 0.1 to 20 percent.
3. The process of forming a population of microcapsules according to claim 1 wherein the monofunctional amine is selected from the group consisting of alkyl amino acrylate and alkylaminomethacrylate.
4. The process of forming a population of microcapsules according to claim 1 wherein the monofunctional amine is tertiarybutylaminoethyl methacrylate dimethylaminoethyl methacrylate or diethylaminoethylmethacrylate.
5. The process of forming a population of microcapsules according to claim 1 wherein the acid and monofunctional amine acrylate or monofunctional amine methacrylate have a molar proportion of from 1.25/1 to about 1/1.25.
6. The process of forming a population of microcapsules according to claim 1 wherein the acid is an organic acid which is substantially water insoluble and is selected from the group consisting of monoalkylmaleates, alkyl benzene sulfonic acid, and trialkylbenzene sulfonic acid.
7. The process of forming a population of microcapsules according to claim 1 wherein the acid is selected from the group consisting of a monofunctional acid acrylate and monofunctional acid methacrylate.
8. The process for forming a population of microcapsules according to claim 1 wherein the organic oil material is selected from the group consisting of hydrocarbons, alcohols, arenes, ketones, carboxylates and esters.
9. The process of forming a population of microcapsules according to claim 1 wherein the acid is a Lewis acid electron acceptor.
10. The process of forming a population of microcapsules according to claim 1 wherein the hydrophilic liquid core material is selected from the group consisting of anionic, cationic, or neutral but polar material.
11. A process for forming a population of microcapsules comprising a liquid hydrophilic core material and a wall material at least partially surrounding the core material, the microcapsule population being formed by:
providing a liquid hydrophilic core material;
providing an oil continuous phase which is low boiling and preferably nonflammable, the oil continuous phase comprising one or more organic oil material with chain length up to about 42 carbons;
dividing the oil continuous phase into oil 1 and oil 2;
dispersing into oil 1 an initiator;
dispersing into oil 2 a multifunctional acrylate or methacrylate monomer or oligomer, and an oil soluble or dispersible monofunctional acid acrylate or monofunctional acid methacrylate having a —COOH content by weight of 20% or greater, and a base;
combining oil 1 and oil 2;
forming a mixture by dispersing the liquid hydrophilic material into the oil continuous phase;
optionally adding a surfactant,
emulsifying the liquid hydrophilic liquid material into the oil continuous phase by subjecting the blend to high shear agitation;
heating the emulsion for a time sufficient to enable the acid acrylate or methacrylate and the multifunctional acrylate or methacrylate to form a higher molecular weight prepolymer which migrates to the emulsified liquid hydrophilic material, thereby forming microcapsules comprising the higher molecular weight prepolymers adhered to and surrounding the hydrophilic core material;
heating for a time and temperature sufficient to crosslink the prepolymers.
wherein the base and monofunctional acid acrylate or monofunctional acid methacrylate have a molar proportion of from 3:1 to 1:3.
12. The process of forming a population of microcapsules according to claim 11 wherein the base and monofunctional acid acrylate or monofunctional acid methacrylate have a percent by weight as compared to weight of the wall material of from 0.1 to 20 percent.
13. The process according to claim 11 wherein the organic oil material of the oil continuous phase are esters.
14. The process of forming a population of microcapsules according to claim 11 wherein the monofunctional acid acrylate or monofunctional acid methacrylate is carboxyalkyl acrylate or carboxyalkyl methacrylate.
15. The process for forming a population of microcapsules according to claim 11 wherein the monofunctional carboxyalkyl acrylate is beta-carboxyethylacrylate.
16. The process of forming a population of microcapsules according to claim 11 wherein the base is an alkaline material that can donate electrons or hydroxide ions or accept protons.
17. The process of forming a population of microcapsules according to claim 11 wherein the base is selected from the group consisting of monofunctional amine acrylate or monofunctional amine methacrylate.
18. The process of forming a population of microcapsules according to claim 11 wherein the hydrophilic liquid core material is selected from the group consisting of anionic, cationic, or neutral but polar material.
19. The process of forming a population of microcapsules according to claim 1 , or 11 wherein the oil continuous phase is selected to be
or, triglycerides of C 6 to C 18 fatty acids.
20. The process of forming a population of microcapsules according to claim 1 or 11 wherein crosslinking the prepolymers is accomplished by heating the mixture or exposing the mixture to actinic radiation or both.