Microcapsule comprising a polyester-urethane shell and a hydrophobic core material
Disclosed herein are microcapsules as core-shell-particles, including a polymeric shell, a method of making them, a dispersion of those microcapsules in a liquid medium and use thereof. The microcapsules include a core that contains a hydrophobic component.
1. A microcapsule comprising a capsule core and a polymeric shell, wherein the core comprises only hydrophobic components and the shell comprises in polymerized form:
A) at least one poly(ester-urethane) comprising at least 2 isocyanate groups, obtainable by reacting at least one polyester-polyol comprising at least 2 OH groups with at least one polyisocyanate comprising at least 2 NCO groups, and;
B1) at least one polymeric polyamine selected from the group consisting of polyaminosaccharides, polyamidoamines, polyesteramines, polyaminoacids and combinations thereof, having an average molecular weight of between about 375 g/mol and about 2500 g/mol, and comprising at least 3 amino groups reactive towards NCO groups.
2. The microcapsule according to claim 1 , wherein the poly(ester-urethane) is a reaction product of the polyester-polyol with the polyisocyanate which is selected from the group consisting of hexamethylene diisocyanate, tetramethylene diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, isophoronediisocyanate, 2,4- and 2,6-toluylene diisocyanate and isomer mixtures thereof, 2,4′- and 4,4′-diphenylmethane diisocyanate and isomer mixtures, biurets, allophanates and/or isocyanurates or mixtures thereof.
3. The microcapsule according to claim 1 , wherein the polyester-polyol is a polylactonepolyol which comprises 2 or 3 OH groups.
4. The microcapsule according to claim 1 , wherein the polyester-polyol is a compound of the formulae (2), (5), or mixtures thereof
wherein
R a is selected from linear or branched C 1 -C 10 -alkylene group and C 3 -C 20 -cycloaliphatic radicals having 3 to 10 ring carbon atoms,
R b is a linear or branched C 1 -C 10 -alkantriyl group,
l, m and n are independently an integer of 1 to 100,
with the proviso that
in the formula (2) n+m is an integer of 2 to 100,
in the formula (5) n+m+1 is an integer of 2 to 100.
5. The microcapsule according to claim 1 , wherein the polyester-polyol has a weight-average molecular weight of from 200 to 3000 g/mol.
6. The microcapsule according to claim 1 , wherein the shell comprises in polymerized form a component B1) which comprises at least one polyamidoamine.
7. The microcapsule according to claim 6 , wherein the at least one polyamidoamine is polylysine and wherein the polylysine has an average molecular weight of 375 to 2500 g/mol.
8. The microcapsule according to claim 1 , wherein a core-shell ratio (w/w) of the microcapsule is 20:1 to 1:1.
9. The microcapsule according to claim 1 , wherein a mean particle size of the microcapsule d(0.5) is in the range from 0.5 μm to 50 μm.
10. The microcapsule according to claim 1 , wherein the hydrophobic components comprise a pesticide.
11. The microcapsule according to claim 1 , wherein the hydrophobic components comprise a pesticide and an oil body selected from the group consisting of vegetable oils, modified vegetable oils, synthetic (tri)glycerides, fatty acid alkyl esters, fatty acid alkyl esters based on C6-C22 fatty acids, mineral oils, hydrocarbons, saturated or unsaturated C6-C30-fatty acids, aromatic compounds, esters of linear C6-C22-fatty acids and mixtures thereof.
12. A microcapsule dispersion comprising at least one microcapsule according to claim 1 .
13. A process for the preparation of the microcapsule according to claim 1 , wherein the capsule core is obtainable by
a) providing a premix (Ib) comprising the hydrophobic component(s) to be encapsulated (Cb), and at least one component (A) as defined in claim 1 , and
b) mixing the premix (Ib) provided in step a) with a hydrophilic medium comprising at least one hydrophilic protective colloid, at least one component (B1) as defined in claim 1 , and reacting a resulting mixture to form microcapsules dispersed in the hydrophilic medium.
14. A method of controlling phytopathogenic fungi and/or undesired plant growth and/or undesired insect or mite attack and/or for regulating the growth of plants, wherein the microcapsule according to claim 1 , where the hydrophobic components comprise a pesticide, is allowed to act on the respective pests, their environment or the crop plants to be protected from the respective pest, on the soil and/or on undesired plants and/or on the crop plants and/or on their environment.
15. The microcapsule according to claim 8 , wherein the core-shell ratio (w/w) of the microcapsule is 10:1 to 2:1.
16. The microcapsule according to claim 15 , wherein the core-shell ratio (w/w) of the microcapsule is 6:1 to 3:1.
17. The microcapsule according to claim 9 , wherein the mean particle size of the microcapsule d(0.5) is in the range from 0.7 μm to 30 μm.
18. The microcapsule according to claim 10 , wherein the hydrophobic components further comprise an oil body.
19. The process according to claim 13 , wherein said providing a premix comprises providing the premix further comprising a hydrophobic medium that is liquid at 20° C. and 1023 mbar different from the (Cb).
20. The microcapsule according to claim 1 , wherein the microcapsule further comprises
B2) at least one compound different from B1) which comprises at least 2 terminal groups which are reactive towards isocyanate-groups and which are selected from OH, NHR, or SH, wherein R is selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl.