Microencapsulation of biocides and antifouling agents
The present invention relates to microencapsulated compositions of isothiazolone derivatives and other water insoluble biocides or antifouling agents. In particular, the present invention relates to microencapsulated 4,5 dichloro 2 n-octyl-3(2H)-isothiazolone(DCOIT), useful in marine antifouling coatings and paints.
1. A microencapsulated biocide comprising an isothiazolone biocide or antifouling agent as a core material encapsulated in a wall material that has a xylene impermeability such that less than 10% of the biocide or antifouling agent is released from the capsule at room temperature to 45° C. over 90 days and from which water or saltwater can leach the biocide from the wall material, wherein the wall material contains a dopant to enhance the diffusion of isothiazolone from the capsule and is a reaction product of polyvinyl alcohol, urea, resorcinol, and formaldehyde resin.
2. The microencapsulated biocide of claim 1 wherein the isothiazolone includes 4,5-dichloro-2-n-octyl-3(2H)-isothiazolone.
3. The microencapsulated biocide of claim 2 wherein the isothiazolone is present in the core dissolved in a partially water soluble solvent.
4. The microencapsulated biocide of claim 1 wherein the dopant is polyvinyl alcohol.
5. The microencapsulated biocide of claim 3 wherein the partially water soluble solvent dissolves in water in an amount of about 0.5 to about 5% and is incorporated into the core in an amount of about 5 to about 25%.
6. The microencapsulated biocide of claim 5 wherein the solvent is an ester or an ether or mixtures thereof.
7. The microencapsulated biocide of claim 1 wherein the wall material is a dual wall microcapsule including a melamine-formaldehyde inner wall.
8. The microencapsulated biocide of claim 1 wherein the dopant is selected from the group consisting of polyvinyl alcohol, hydroxylethylcellulose, hydroxypropylcellulose, methylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, hyroxybutylmethylcellulose, ethylhydroxyethylcellulose, and polyethylene glycols.
9. The microencapsulated biocide of claim 1 wherein the wall material is a dual wall having an inner wall and an outer wall.
10. The microencapsulated biocide 9 wherein the inner wall includes is an acrylic polymer and the outer wall is a PVA-urea-resorcinol-formaldehyde(URF) polymer.
11. The microencapsulated biocide of claim 9 wherein the inner wall is an interfacial reaction product of an aromatic polyisocyanate and the outer wall is a PVA-urea-resorcinol-formaldehye(URF) condensation polymer.
12. The microencapsulated biocide of claim 9 wherein the inner wall is a melamine-formaldehyde and the outer wall is a PVA-urea-resorcinol-formaldehye(URF) polymer.