Search

EP-4739739-A1 - ANTIFOULING PAINT COMPOSITION

EP4739739A1EP 4739739 A1EP4739739 A1EP 4739739A1EP-4739739-A1

Abstract

An antifouling coating composition comprising: (A) a binder comprising (i) a (meth)acrylic copolymer comprising 0.5 to 10 wt% (meth)acrylic acid monomers relative to the total weight of monomers in the (meth)acrylic copolymer; and/or (ii) a metal containing (meth)acrylic copolymer wherein the metal is selected from Zn or Cu; (B) 1.0 to 25 % solids volume cuprous oxide; and (C) 1.0 to 65 % solids volume hollow spheres.

Inventors

  • LANGSETH, Eirin
  • JOHNSEN, HENNING
  • Jackson, Seamus Michael

Assignees

  • Jotun A/S

Dates

Publication Date
20260513
Application Date
20240702

Claims (17)

  1. 1. An antifouling coating composition comprising: (A) a binder comprising (i) a (meth)acrylic copolymer comprising 0.5 to 10 wt% (meth)acrylic acid monomers relative to the total weight of monomers in the (meth)acrylic copolymer; and/or (ii) a metal containing (meth)acrylic copolymer wherein the metal is selected from Zn or Cu; (B) 1.0 to 25 % solids volume cuprous oxide; and (C) 1.0 to 65 % solids volume hollow spheres.
  2. 2. An antifouling coating composition as claimed in any preceding claim wherein the binder (A) further comprises a monocarboxylic acid or metal salt thereof (iii), preferably rosin, hydrogenated rosin or a metal salt thereof.
  3. 3. An antifouling coating composition as claimed in any preceding claim wherein the hollow spheres comprise ceramic or glass.
  4. 4. An antifouling coating composition as claimed in any preceding claim wherein the total amount of cuprous oxide and hollow spheres combined is in the range 8.0 to 70 SV%, such as 15 to 70 % solids volume based on the antifouling coating composition as a whole, such as 15 to 60 % solids volume.
  5. 5. An antifouling coating composition as claimed in any preceding claim wherein the hollow spheres are hollow microspheres and preferably have a d50 between 10 and 100 pm.
  6. 6. An antifouling coating composition as claimed in any preceding claim comprising (B) 1.5 to 15 % solids volume cuprous oxide; and (C) 5.0 to 60 % solids volume hollow spheres.
  7. 7. An antifouling coating composition as claimed in any preceding claim wherein the binder (A) further comprises a (meth)acrylic polymer (iv).
  8. 8. An antifouling coating composition as claimed in claim 7 wherein the (meth)acrylic polymer (iv) comprises as monomers: i. at least one, such as at least two, (meth)acrylate of Formula (I): wherein R 1 is H or CH3, and R 2 is a C1-C20 hydrocarbyl substituent, preferably a Cl-10 alkyl substituent, such as a Cl-8 alkyl.
  9. 9. An antifouling coating composition as claimed in claim 8 wherein the (meth)acrylic polymer (iv) comprises at least one monomer of formula (V) wherein R 7 is H or CH3, and R 8 is a C3-40 substituent, such as C3-C20 substituent, containing at least one oxygen or nitrogen atom.
  10. 10. An antifouling coating composition as claimed in any preceding claim wherein the (meth)acrylic copolymer (i) is present and comprises as monomers at least one, such as at least two, (meth)acrylate of Formula (I): wherein R 1 is H or CH3, and R 2 is a C1-C20 hydrocarbyl substituent, preferably a Cl-10 alkyl substituent, such as a Cl -8 alkyl; and (meth)acrylic acid.
  11. 11. An antifouling coating composition as claimed in claim 1 to 10 comprising: (A) a binder comprising a (meth)acrylic copolymer (i) wherein the (meth)acrylic copolymer (i) is present in an amount of 1.0 to 12 wt%, preferably 2.0 to 7.0 wt%, relative to the total weight of the coating composition as a whole; (B) 1.0 to 25% solids volume cuprous oxide; and (C) 1.0 to 65 % solids volume hollow spheres. wherein the total amount of cuprous oxide and hollow spheres combined is in the range of 15 to 70 % solids volume.
  12. 12. An antifouling coating composition as claimed in any preceding claim wherein the metal containing (meth)acrylic copolymer comprising a monomer which is a (meth)acrylate monomer comprising side chains of formula (II) -COO-M-O-COR 3 (II) wherein M represents zinc or copper and R 3 represents an organic group.
  13. 13. An antifouling coating composition as claimed in any preceding claim further comprising at least one additional biocide such as copper pyrithione, zinc pyrithione, zineb and 4,5-dichloro-2-octyl-4-isothiazolin-3-one, preferably copper pyrithione.
  14. 14. An antifouling coating composition as claimed in any preceding claim which contains less than 1.0 wt% of a liquid, acyclic, saturated C12-24 monocarboxylic acid or salt thereof or liquid, acyclic branched Cl 2-24 monocarboxylic acid or salt thereof, such as contains no such material.
  15. 15. An antifouling coating composition as claimed in any preceding claim where if the coating composition is based on binder component (i), the coating composition contains 10 to 30.0 wt% cuprous oxide, such as 10 to 28 wt% cuprous oxide; or where the coating composition is based on binder component (ii), the coating composition contains 10 to 40 wt%, such as 10 to 35 wt%, preferably 10 to 30 wt% cuprous oxide.
  16. 16. A process for protecting an object from fouling, said process comprising coating at least a part of said object which is subject to fouling with an antifouling coating composition as claimed in any of claims 1 to 15.
  17. 17. A substrate coated with an antifouling coating composition as claimed in any of claims 1 to 15.

Description

Antifouling Paint Composition This invention relates to an antifouling paint composition comprising a (meth)acrylic copolymer comprising (meth)acrylic acid monomers and/or a metal containing (meth)acrylic copolymer, cuprous oxide and hollow spheres. The composition may additionally contain a silyl ester copolymer and/or a monocarboxylic acid or metal salt thereof. The invention further relates to a method of protecting objects from fouling by applying the antifouling coating composition of the invention to the object, and to objects coated with the antifouling composition of the invention. Background Copper containing self-polishing paints are the most commonly used antifouling paints. Cuprous oxide is a broad-spectrum biocide active against animal fouling. After release into seawater, the cuprous oxide transforms into less toxic compounds relatively quickly and for this reason it can be used in antifouling paints at high concentration. However, reduction in the overall use of biocides would be beneficial from an environmental perspective as long as the overall performance of the antifouling paint could be maintained. Cuprous oxide is still a preferred biocide in antifouling paints but more efficient use of the added cuprous oxide will provide a more sustainable and economical product. The present inventors therefore sought an antifouling paint in which the levels of cuprous oxide could be reduced. However, reducing the cuprous oxide level is not trivial. If cuprous oxide content in the paint is reduced then there is a corresponding requirement to increase the content of something else to ensure that the other properties of the paint remain the same. For example, cuprous oxide has a relatively low oil absorption compared to many of the typical fillers used in antifouling paints and therefore a 1 : 1 replacement by volume of cuprous oxide with a filler is not a viable solution as such a product will be much more viscous and will consequently require more solvent to keep the viscosity of the paint at an acceptable level for application. More solvent means more volatiles and many countries have strict limits on the volatile content in paints. Simply substituting less of a higher oil absorbing filler is also problematic as the resulting paint composition will have a lower pigment volume concentration negatively affecting the properties of the coating film. Reformulating the antifouling paint to reduce the cuprous oxide content is therefore challenging. The present inventors propose to use hollow spheres, in particular hollow microspheres, as a partial replacement for cuprous oxide. The inventors have surprisingly found that the use of hollow spheres as a partial replacement for cuprous oxide results not only in a functioning antifouling paint but is also associated with several further benefits. The density of copper containing antifouling paints is close to 2 g/mL, meaning that a 20 L paint container supplied to customers weighs close to 40 kg. Replacing parts of the cuprous oxide (specific gravity 5.8 g/cm3) with light weight hollow spheres (specific gravity e.g. 0.2-0.5 g/cm3) can provide antifouling paint with much lower weight. If a 20 L can weigh 30 kg rather than 40 kg, handling during transportation and in the shipyards will be easier, and fuel consumption under transportation will be lowered. In addition, if the same dry film thickness is applied to a substrate, such as a vessel, the reduction of weight of the antifouling coating on the vessel will be significant leading to less fuel consumption when such a vessel is sailing. Lower fuel consumption due to lighter weight will lead to reduced emission of greenhouse gases. Organic solvents such as xylene are needed in solvent borne paints to keep the viscosity at an acceptable level for application e.g. by spray application. Hollow spheres have a low oil absorption and high volume/weight ratio due to low specific gravity. The inventors have found that replacing cuprous oxide (or other conventional fillers) with hollow spheres tends to reduce viscosity, meaning the amount of organic solvent can be reduced while still having a paint suitable for spray application. Reduction in volatile organic content (VOC) is advantageous from an environmental and health and safety point of view. The combination of reduced biocide level, lower VOC and lower density products results in an antifouling product with an improved sustainability profile. In one embodiment, hollow spheres should preferably not be polymeric, due to the non-desirable environmental effect of plastic pollution being released during polishing of the paint on a vessel. The use of hollow glass or ceramic spheres is therefore preferred. Removing some of the cuprous oxide and replacing with hollow spheres will also reduce cost as the price of cuprous oxide is high. If these aims can be achieved without any substantial loss in antifouling performance, such a produce is clearly advantageous. The literatu