Self-polishing type antifouling coating composition containing film-formable metal soap compound

An antifouling coating composition includes a binder copolymer which contains one or more copolymerizable ethylenically unsaturated monomers or oligomers wherein at least one of said monomers or oligomers has a hydroxy group, a copolymerizable silicone monomer or oligomer, and a film formable metal soap compound which is prepared by reacting a metal compound containing a metal having a valency of at least 2 with an unsaturated fatty acid or alcohol.

FIELD OF THE INVENTION 
The present invention relates to an antifouling coating composition, and 
particularly to a self-polishing type antifouling coating comprising a 
hydrolyzable resinous binder composition which contains a film-formable 
metal soap compound. 
BACKGROUND OF THE RELATED PRIOR ART 
Antifouling paints are well known for use in coating the surface of the 
submarine parts of a ship's hull in order to protect them from fouling 
resulting from the growth of marine organisms on the surface. Typically, 
an antifouling paint contains an antifouling agent which can be freed from 
the surface of the paint to the marine organisms accumulated on the hull 
surface by concentration gradient. Self-polishing type antifouling paints 
are gradually dissolvable in seawater to continuously reveal, over a 
period, a fresh anti-fouling paint surface which permits release of the 
antifouling agent. Such self-polishing type antifouling paints contain a 
film-forming resin which is hydrolyzable by seawater. 
Metal soaps prepared by reacting high hydrophobic saturated fatty acids 
such as naphthenic acid with a compound of a multi-valent metal such as 
Co, Mn, Zn, Cu or Ca are commercial products well known as driers and 
catalysts for paints. The metal soaps produced from such saturated fatty 
acids do not function as a film-forming binder. 
U.S. Pat. No. 2,423,044 discloses a hydrolyzable resin composition which 
comprises an acrylic resin having at least one side chain bearing at least 
one metal ester containing terminal group. The patent suggests use of 
monovalent organic acids to react with a metal compound for the formation 
of the metal ester containing terminal group. The monovalent organic acids 
as disclosed are saturated organic acids including saturated fatty acids. 
The basic U.S. application of this application discloses a self-polishing 
type antifouling coating composition which comprises a metallic soap 
compound prepared by reacting a metal compound containing a metal having a 
valency of at least 2 with at least an unsaturated fatty acid or alcohol. 
The metallic soap compound formed thereby is used as a film-forming binder 
for the coating position. 
SUMMARY OF THE INVENTION 
An object of the invention is to provide a self-polishing antifouling 
coating composition comprising a film formable metal-soap resin modified 
by a silicone resin which is of low surface tension thereby reducing 
accumulation of microorganisms on the surface of a ship hull. 
According to the invention, a self-polishing type antifouling coating 
composition containing a copolymer formed of a film-forming binder 
composition comprises: 
one or more copolymerizable ethylenically unsaturated monomers or oligomers 
wherein at least one of said monomers or oligomers has a hydroxy group; 
a copolymerizable silicone monomer or oligomer; and 
a film formable metal soap compound which is prepared by reacting a metal 
compound containing a metal having a valency of at least 2 with an 
unsaturated fatty acid or alcohol: 
wherein said copolymer contains a group having a general formula 
EQU --(A1).sub.n --M--(A2--R1).sub.m 
wherein R1 is a alkenyl group derived from an unsaturated fatty acid or 
alcohol, M is a metal having a valency of at least 2, A1 and A2 are 
independently a functional group of a carboxylic acid, a sulfonic acid or 
a phosphoric acid, and each of n and m=1 or 2, and n+m =2 or 3. 
According to one aspect of the invention, the hydrolyzable antifouling 
coating composition further comprises an effective amount of an 
antifouling agent which is a metallic compound other than said metal soap 
compound. 
The film formable metal soap compound used in the present invention may be 
prepared by reacting a metal compound with an unsaturated fatty acid, a 
mixture of unsaturated fatty acid or a mixture containing at least one 
unsaturated fatty acid. 
The unsaturated fatty acids useful for the invention comprises oleic acid, 
linoleic acid, linolenic acid, eleostearic acid, lincanic acid, ricinoleic 
acid, erucic acid and may be obtained from castor oil, soybean oil, corn 
oil, cotton seed oil, linseed oil, oiticica oil, perilla oil, poppyseed 
oil, rapeseed soil, safflower oil, sunflower oil, tall oil, tung oil, 
walnut oil, herring oil, menhaden oil and sardine oil. The above 
unsaturated acids may be converted into a fatty alcohol which can be used 
to prepare a phosphoric or sulfonic acid obtaining an unsaturated 
aliphatic group. 
The metal compound may be an oxide, a hydroxide or a chloride. Most of the 
metals in the Periodic table with a valency of at least 2 can be used in 
the present invention. They may be the metals belonging to Group Ib, IIa, 
IIb, IIIa, IIIb, IVa, IVb, Va, Vb, VIIa and VIII. The type of metal 
contained in the metal compound has a considerable influence on the rate 
of hydrolysis of the metallic soap binder. Soaps of alkali metals are 
readily soluble in water whereas soaps prepared from alkaline earth metals 
are water insoluble but hydrolyzable in water. Different alkaline earth 
metals may result in different hydrolysis rates. For example, an alkaline 
earth metal with higher molecular weight such as barium shows a slower 
hydrolysis rate that other alkaline earth metal having lower molecular 
weight such as magnesium. The rate of hydrolysis also varies when using 
metals of Group III, IV and transition metals such as Al, Co, Zn, Mn, Co, 
etc. 
The ethylenically unsaturated monomers or oligomers suitable for the 
present invention comprises acrylic monomers and unsaturated organic acids 
containing --COO, --OSO.sub.2 --, or --O--PO.sub.3, Examples of such 
unsaturated organic acids and monomers are methacrylic acid, acrylic acid, 
p-styrene sulfonic acid, 2-methyl-2-acrylamide propane sulfonic acid, 
methacryl acid phosphoxy propyl, methacryl acid phosphoxy ethyl, itaconic 
acid and maleic acid. Hydroxyl containing monomers may be hydroxyl 
containing acrylic monomers such as hydroxyethylmethacrylate, 
hydroxymethylmethacrylate, hydroxyethylacrylate, and 
hydroxymethylacrylate. 
Other monomers copolymerizable with the above ethylenically unsaturated 
monomers or oligomers are vinyl acetate, vinyl propionate, monoakyl 
itaconate, monoakyl maleate, methyl acrylate, ethyl acrylate, propyl 
acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, methyl 
methacrylate, acid anhydrides such as maleic anhydride and itaconic 
anhydride, vinyl monomers containing an amide group such as acrylamide and 
vinyl monomers containing an amino group. 
The copolymerizable silicone monomer may be any of silicon compounds having 
one or more hydroxy or alkoxy groups directly bonded to a silicon atom. 
Some examples of such silicon compounds are trimethylmethoxysilane, 
tri(1-methylethyl)ethoxysilane, di(1-methylpropyl)diethoxysilane, and 
ethyltriethoxysilane. The silicone oligomers may be siloxane oligomers 
containing one or more hydroxy or alkoxy groups such as methoxy or ethoxy 
functional groups. Examples of such oligomers are methoxy-functional, low 
molecular weight silicone resins which are manufactured by Dow Corning 
Corporation under the brand names of Dow Corning Q1-3074 and Dow Corning 
3037 and by the Wacker Company under the brand name of Wacker Silicone 
Intermediate SY-231. 
Other polymers may be blended with the copolymer prepared according to the 
present invention. Preferably, such polymers are water soluble. Examples 
of them are rosin, polyacrylamide and other polymers containing 
hydrophilic groups such as polyesters and polyurethanes containing a 
carboxylic acid group, a sulfonic acid group, a phosphoric acid group, an 
amino group or an amide group.

The present invention will be now more fully explained in the following 
examples. 
EXAMPLE 1 
A solution containing 20 parts of hydroxyethylmethacrylate, 80 parts of 
butylacrylate, 30 parts of acrylic acid and 70 parts of methyl 
methacrylate and a solution containing 3 parts of benzoyl peroxide 
dissolved in 60 parts of toluene were added to a reaction kettle which 
contained 48 parts of butanol and 192 parts of xylene within a period of 2 
hours at 120.degree. C. 
The reaction kettle was maintained at 120.degree. C. for another 2 hours to 
complete the polymerization. Then 40 parts of copper hydrate, 117 parts of 
linseed fatty acid and 34 parts of a methoxy functional silicone oligomer 
(manufactured by the Wacker company and sold under the brand name of 
Silicone Intermediate SY231) were added to the reactor and refluxed to 
chase out the low boiling point components until a theoretical amount 
thereof was obtained. A clear solution was obtained. 
EXAMPLE 2 
51 parts of a methoxy functional silicone oligomer (manufactured by the 
Wacker company and sold under the brand name of Silicone Intermediate 
231), 52 parts of copper hydrate, 156 parts of linseed fatty acid, 30 
parts of hydroxyethylmethacrylate, 40 parts of acrylic acid and 200 parts 
of xylene and N-butanol were placed in a reactor. The mixture was refluxed 
to chase out low boiling point components until a theoretical amount 
thereof was obtained. The obtained solution and a solution containing 1.5 
parts of benzoyl peroxide dissolved in 20 parts of toluene and a solution 
containing 30 parts of butylacrylate and 30 parts of 2-ethylhexylacrylate 
were added into a reaction kettle within 1 hour at 120.degree. C. 
Furthermore, a solution containing 35 parts of butylacrylate and 35 parts 
of 2-ethylhexylacrylate and a solution containing 2.5 parts of benzoyl 
peroxide dissolved in 30 parts of toluene were added into the reaction 
kettle with a period of 2 hours at the same temperature. The reaction 
kettle was maintained at 120.degree. C. for another 2 hours to complete 
the polymerization. 
EXAMPLE 3 
A solution containing 20 parts of hydroxyethylmethacrylate, 70 parts of 
butylacrylate, 10 parts of acrylamide, 30 parts of acrylic acid and 70 
parts of methyl methacrylate and a solution containing 3 parts of benzoyl 
peroxide dissolved in 60 parts of toluene were added to a reaction kettle 
which contained 48 parts of butanol and 192 parts of xylene within a 
period of 2 hours at 120.degree. C. 
The reaction kettle was maintained at 120.degree. C. for another 2 hours to 
complete the polymerization. Then 40 parts of copper hydrate, 117 parts of 
linseed fatty acid and 34 parts of a methoxy functional silicone oligomer 
(manufactured by the Wacker company and sold under the brand name of 
Silicone Intermediate 231) were added to the reactor and refluxed to chase 
out the low boiling point components until a theoretical amount thereof 
was obtained. A clear solution was obtained. 
EXAMPLE 4 
51 parts of a methoxy functional silicone oligomer (manufactured by the 
Wacker company and sold under the brand name of Silicone Intermediate 
231), 52 parts of copper hydrate, 156 parts of linseed fatty acid, 30 
parts of hydroxyethylmethacrylate, 40 parts of acrylic acid and 200 parts 
of xylene and N-butanol were placed in a reactor. The mixture was refluxed 
to chase out the low boiling point components until a theoretical amount 
thereof was obtained. The obtained solution and a solution containing 1.5 
parts of benzoyl peroxide dissolved in 20 parts of toluene and a solution 
containing 30 parts of butylacrylate and 30 parts of 2-ethylhexylacrylate 
were added into a reaction kettle within 1 hour at 120.degree. C. 
Furthermore, a solution containing 30 parts of butylacrylate, 30 parts of 
2-ethylhexylacrylate and 10 parts of acrylamide and a solution containing 
2.5 parts of benzoyl peroxide dissolved in 30 parts of toluene were added 
into the reaction kettle with a period of 2 hours at the same temperature. 
The-reaction kettle was maintained at 120.degree. C. for another 2 hours 
to complete the polymerization. 
COMATIVE EXAMPLE 1 
A solution containing 30 parts of acrylic acid, 90 parts of butylacrylate 
and 80 parts of methyl methacrylate and a solution containing 3 parts of 
benzoyl peroxide dissolved in 60 parts of toluene were added to a reaction 
kettle which contained 48 parts of N-butanol and 192 parts of xylene 
within a period of 2 hours at 120.degree. C. 
The reaction kettle was maintained at 120.degree. C. for another 2 hours to 
complete the polymerization. Then 40 parts of copper hydrate and 117 parts 
of linseed fatty acid were added to the reactor and refluxed to chase out 
the low boiling point components until a theoretical amount thereof was 
obtained. A clear solution was obtained. 
EXAMPLES 5-8 
Antifouling paints were prepared from the resins of Examples 1-4 using the 
following formulations: 
______________________________________ 
Component Amount 
______________________________________ 
Resin 25 
Cu.sub.2 O 40 
Bentone #34 1.5 
Talc 10 
CaCO.sub.3 5 
Xylene 10 
______________________________________ 
The physical properties and antifouling properties of the antifouling 
paints are summarized in Table I. Control 1 was prepared from a 
chloro-rubber resin and Control 2 was prepared from a self-polishing 
organotin resin. Control 3 was prepared from the resin of Comparative 
Example 1. From a comparison of Examples 5-8 with Control 3, it can be 
seen that the coating composition containing a silicone resin improves the 
impact resistance and the antifouling effect of the coating as compared to 
the coating which contains no silicone resin. 
TABLE I 
______________________________________ 
Example Con- Con- Con- 
5 6 7 8 trol 1 
trol 2 
trol 3 
______________________________________ 
Hardness H HB H H H H H 
Viscosity (ku) 
87 76 90 90 85 93 95 
Impact Resistance.sup.a 
G G G G G G F 
(500 g .times. 50 cm) 
Antifouling.sup.b (%) 
After one month 
0 0 0 0 0 0 0 
After three months 
20 15 10 10 30 2 25 
After six months 
40 35 30 30 70 20 55 
After nine months 
70 65 60 60 100 60 80 
______________________________________ 
.sup.a : G: good F: fair 
.sup.b : Antifouling tests were performed by dipping the testing plates 
into the sea, and the antifouling ability is expressed by the percentage 
of fouling area.