Europäisches Patentamt *EP001479737A1* (19) European Patent Office Office européen des brevets (11) EP 1 479 737 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int Cl.7: C09D 5/16 24.11.2004 Bulletin 2004/48 (21) Application number: 04291279.0 (22) Date of filing: 19.05.2004 (84) Designated Contracting States: • Abrams, Michael B. AT BE BG CH CY CZ DE DK EE ES FI FR GB GR Philadelphia, Pennsylvania 19128 (US) HU IE IT LI LU MC NL PL PT RO SE SI SK TR • Silverman, Gary S. Designated Extension States: Chadds Ford, Pennsylvania 19317 (US) AL HR LT LV MK • Mountz, David A. King of Prussia, Pennsylvania 19406 (US) (30) Priority: 21.05.2003 US 442461 • Obiols, Jérome 10.11.2003 US 705693 69003 Lyon (FR) (71) Applicant: Atofina Chemicals, Inc. (74) Representative: Treuil, Claude Philadelphia, PA 19103-3222 (US) Atofina Département Propriété Industrielle (72) Inventors: 4-8 cours Michelet • Aubart, Mark A. La Défense 10 Malvern, Pennsylvania 19355 (US) 92091 Paris La Défense Cedex (FR) • Kuo-Shu Tseng, Kenneth Lawrenceville, New Jersey 08648 (US) (54) Triarylsilyl(meth)acryloyl-containing polymers for marine coating compositions (57) Polymers containing triarylsilyl(meth)acryloyl units are erodible in seawater and can be used to formulate antifouling marine paints. The polymers are characterized by low levels of triarylsilyl(meth) acrylate units and an erosion rate in seawater of 2 to about 15 µm per month. EP 1 479 737 A1 Printed by Jouve, 75001 PARIS (FR) EP 1 479 737 A1 Description FIELD OF THE INVENTION 5 [0001] This invention relates to polymers for self-polishing marine antifouling paints. More particularly, the invention relates to polymer binders, which provide an erosion rate in seawater that is suitable for use in marine antifouling paints. These polymer binders contain pendant triarylsilyl(meth)acryloyl group at lower levels than previously believed nec- essary to achieve an erosion rate in seawater that is suitable for use in marine antifouling paints. The polymers are characterized by an erosion rate in seawater of about 2 to about 15 µm/month. 10 BACKGROUND OF THE INVENTION [0002] The polymers widely used at present to fabricate self-polishing marine antifouling paints are polymers that contain pendant organotin ester (e.g., acrylate) groups. Indeed, marine antifouling paints based on organotin acrylate 15 polymers have dominated the market for over 20 years. The organotin acrylate-containing polymers, when formulated into a paint and applied to the bottom (i.e., hull) of a marine vessel, hydrolyze in seawater to release an organotin compound (usually tributyltin oxide) that is an active antifoulant preventing marine plants and other organisms from adhering to the vessel bottom. This fouling (i.e., undesirable attachment of organisms to a marine surface) results in increased drag which can significantly increase fuel consumption and, therefore, operating costs. In addition, movement 20 of the vessel through water erodes the paint surface to constantly expose a fresh polymer surface to the hydrolytic effect of seawater. This constant erosion of the paint surface results in the development and maintenance of a smooth surface on the immersed exterior of the marine vessel, which also contributes to reduced drag and greater efficiency. [0003] Further, these paints, properly formulated and applied, have the ability to remain effective for 5 years. This is important because large vessels (e.g., oil tankers and container ships) are dry-docked at 5-year intervals for routine 25 maintenance and inspection; it is most convenient to repaint the hull exterior during these periodic maintenance epi- sodes. [0004] Although effective, the use of organotin-containing polymers in antifouling marine paints has come under attack due to the adverse effect that organotin compounds are believed to have upon the marine environment. The U. S. Environmental Protection Agency (EPA) has significantly restricted the continued use of organotin compounds and 30 the Marine Environmental Protection Committee (MEPC) of the International Maritime Organization (IMO), a unit of the United Nations, has recently approved a resolution to phase out and eventually prohibit the use of organotin- containing materials in antifouling paints. [0005] As a result, there is a need in the art for improved erodible antifouling paint compositions comprising film- forming polymers that are free of tin, while retaining the good antifouling and self-polishing properties as well as the 35 longevity of the organotin-containing antifouling paints. [0006] U.S. Patent 4,593,055 discloses that silylacrylate copolymers of formula 40 45 50 where X is H or CH3 R is selected from the group consisting of -SiR'nR"3-n or -Si(OR'nR"3-n)3 wherein R' and R" are independently straight or branched chain alkyl C1-C10 or phenyl and n = 0-3 are useful to formulate marine antifoulant coatings. The organosilylacrylate component is present in the Examples in amounts ranging from 20 to 40 mole percent. 55 [0007] U.S. Patent 5,436,284 discloses that copolymers containing silylacrylate units are useful to formulate marine antifoulant coating compositions. The Examples (Monomer A4 in Table 3) show arylsilylacrylate copolymers containing 45 and 50 percent by weight of arylsilylacrylate component. [0008] EP 1 127 925 A1 discloses polymeric binders for marine antifoulant paints that contain triarylsilylacrylate 2 EP 1 479 737 A1 groups. The patent teaches that the polymer contains from 20 to 70 percent by weight of triarylsilyl(meth)acrylate, preferably from 30 to 65 percent by weight, and more preferably from 50 to 60 percent by weight. [0009] U.S. Patent 5,795,374 discloses marine antifoulant paints formulated from polymers containing triorganosilyl groups; Monomer M4 is diphenyl-t-butylsilyl acrylate, which is employed in an amount of 10 wt% to make polymer S4. 5 This weight represents about 3 mole%, which, as will be seen from the data, is too low for proper erosion of the polymer film. [0010] U.S. Patent 4,593,055 discloses that marine antifouling paints can be formulated from copolymers containing a hydrolysable triorganosilyl residue, including an arylsilyl residue. The preferred level of triorganosilyl acrylate or methacrylate in the copolymer is from 25 to 40 mole percent. 10 [0011] WO91/14743 discloses erodible marine antifoulant paints with polymeric binders having organosilyl functional groups with the paint having increased storage stability when containing antifouling agents containing copper or zinc. Increased paint storage stability is obtained by using monoamine and quaternary ammonium compounds which inhibit gelation associated with such binders and copper or zinc containing antifouling agents. [0012] Additional patents that concern triorganosilyl containing polymers as binders for marine antifouling paints are: 15 JP 63-057676 which discloses adding a polymethyl silsesquioxane powder for stability when the paint has copper containing antifoulant compounds ; EP 714 957 B1 which discloses a copolymer containing a triorganosilylacrylate and as an essential ingredient a monomer containing an acryloyloxy, a methacryloyloxy, maleinoyloxy or fumaroyloxy group ; EP 802 243 B1 which discloses a marine antifouling paint having an organosilylacrylate based polymeric binder and a rosin compound to improve the erosion rate of the paint; 20 [0013] The following listed patents and applications further disclose terpolymers comprising triorganosily(meth) acry- loyl pendant groups useful as binders in marine antifouling coatings: EP 646 630 B1, EP 775 733 A1, EP 1 016 681 A2, EP 1 127 925 A1, JP 8-269389A, US 4,594,365, US 5,436,284, US 5,795,374, WO 84/02915, WO 91/14743, WO 00/77102A1. 25 BRIEF DESCRIPTION OF THE DRAWINGS [0014] Figure 1 illustrates the relationship between mole percent triphenylsilyl(meth)acrylate residue in a polymer and the erosion rate in seawater of the polymer and compares those erosion rates with that of a triorganotin-based polymer. Each phenyl group can be substituted or un-substituted or a heterocyclic aromatic group and each can be 30 the same or different. [0015] Figures 2 and 3 illustrate the rotor test apparatus used to determine erosion rate. SUMMARY OF THE INVENTION 35 [0016] The present invention relates to the discovery that triarylsilyl(meth)acrylate-containing polymers, where the triarylsilyl(meth)acrylate component is present at surprisingly low levels, are useful to produce marine antifouling paints that have self polishing properties. [0017] In one aspect, the invention relates to seawater-erodible polymers comprising the residue of triarylsilyl(meth) acrylate monomer and the residue of two or more ethylenically unsaturated monomers copolymerizable with said tri- 40 arylsilyl(meth)acrylate monomer, said polymer characterized by an erosion rate in seawater of 2 to 15 µm/month. [0018] As used herein, the term "copolymer" includes polymers comprising two or more different monomeric units, e.g. polymers containing three different monomeric units, also known as terpolymers. Also, in practicing the present invention, mixtures of polymers may be used in antifouling paint compositions with the proviso that the total of the triarylsilyl(meth)acrylate is greater than 9 mole percent and less than 20 mole percent for the mixture of polymers even 45 though each individual polymer may be outside the mole percent range of greater than 9 mole percent and less than 20 mole percent. [0019] In another embodiment, the present invention relates to a self-polishing antifouling marine coating which comprises a triarylsilyl(meth)acrylate-containing polymer and a toxicant, the triarylsilyl(meth)acrylate-containing poly- mer containing from above 9 to about 20 mole percent of triarylsilyl(meth)acryloyl component and characterized by an 50 erosion rate in seawater of from about 2 to about 15 µm/month. [0020] In another embodiment, the invention relates to triarylsilyl(meth)acrylate-containing polymers wherein the mole percentage of the triarylsilyl(meth)acryloyl component is in the range of from above 9 to about 20 mole percent.