A non-toxic antifouling coating composition containing 50 to 99% by weight as the resin solid content of (A) a reaction-curable silicone resin composition and 1 to 50% by weight a solid content of (B) a silicone resin having an average molecular weight of 250 to 30,000, a viscosity of 20 to 50,000 centistokes and alkoxy group at its molecular terminal, and represented by the general formula (I): ##EQU1## where R is hydrogen atom, alkyl group having 1-10 carbon atoms, aryl group or aralkyl group, R.sup.1 is bivalent aliphatic hydrocarbon group having 1-10 carbon atoms, which may be bonded directly or through ether group, ester group or --NH--group, R.sup.2 is lower alkyl group having 1-6 carbon atoms, X and Y are represented respectively as 0.01.ltoreq.X<4.0, 0.01.ltoreq.Y<4.0 and 0.02.ltoreq.X+Y<4.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
The present invention relates to a non-toxic antifouling coating 
composition free of a toxic antifouling agent, and more particularly to a 
coating composition which is coated on underwater structures such as 
ships, port facilities, buoys, pipelines, bridges, submarine stations, 
submarine oil field excavation facilities, water conduit raceway tubes in 
the power plant, cultivating fishing nets, stationary fishing nets and the 
like to provide an antifouling film which is formed on the surface of the 
underwater structure and which is suitable for preventing underwater 
living things from adhering and growing on the surface of the underwater 
structure. 
(2) Description of the Prior Art 
A large number of living things such as the barnacle, ascidian, serupulas, 
mussel, fresh-water mussel, polyzoan, green laver, sea lettuce and the 
like live in the waters of the sea, the river, the lake and swamp, etc., 
and of underwater structures including any surface parts of the structure 
that are splashed as well as parts that are submerged and these living 
things cause various types of damage. Adhesion of the living things to a 
ship, for example, increases frictional resistance to water and causes a 
reduction of the ships sailing speed, resulting in an increased fuel 
consumption in order to keep a constant sailing speed which is undesirable 
from an economical point of view. On the other hand, adhesion of the 
living things to stationary structures, which are fixed under water or on 
the surface of the water, for example, port facilities, makes it difficult 
for these facilities to satisfactorily fulfill their proper functions, and 
further results in constant attacks and a resultant wear and tear on the 
base materials of the facilities. Adhesion of the living things to 
cultivating fishing nets and stationary fishing nets may result in a 
blocking of the nets and cause the death of fish. 
In order to prevent the underwater living things from adhering to the 
underwater structures and growing thereon, the antifouling coating 
compositions prepared by incorporating a toxic antifouling agent such as 
an organotin compound, copper suboxide or the like, have been coated on 
the underwater structures. A coating of the above antifouling coating 
composition on the underwater structures could almost prevent the 
underwater living things from adhering thereto and growing thereon. 
However, the use of the toxic antifouling agent is undesirable from the 
standpoints of environmental safety and hygiene during the preparation and 
coating of the above antifouling coating composition, and further the 
gradual leaching of the antifouling agent into the water may result in 
pollution in the water area with adverse effects on fish and shellfish 
over a long period of time. On the other hand, in order to solve the above 
problems, there has been proposed the non-toxic antifouling coating 
compositions, which are free of the above toxic antifouling agents, or 
which are prepared by use of an oligomer-like room temperature curing 
silicone resin alone, its mixture with silicone oil, or a mixture of the 
oligomer-like room temperature curing silicone resin with liquid paraffin 
or petrolatum. The use of the above non-toxic antifouling coating 
compositions all consists in reducing the surface tension of their films 
so as to impart antifouling properties, all resulting in poor antifouling 
properties and antifouling durability which causes problems in practical 
use. 
As a non-toxic antifouling coating composition free of the above problems, 
there is proposed an antifouling coating composition which comprises a 
reaction-curable silicone resin and a silicone resin having a polar group 
such, as a hydroxyl group, amino group, carboxyl group, epoxy group or the 
like as a molecular terminal group (see Japanese Patent Application 
Laid-Open Nos. 252480/87 and 43973/88). 
Exudation of the polar group-containing silicone resin which has poor 
compatibility to the surface due to volume shrinkage caused by the 
reaction-curing of the reaction-curable silicone resin results in breaking 
the base to which the underwater living things adhere to show good 
antifouling properties. Recently, however, further improvement in 
antifouling properties and antifouling durability has been highly 
demanded. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a non-toxic antifouling 
coating composition which has highly improved antifouling properties and 
antifouling durability. 
It has been found that the use of an alkoxy group-containing silicone resin 
substantially incapable of reacting with the reaction-curable silicone 
resin and having an alkoxy group introduced at its molecular terminal 
through an ethylene oxide group or propylene oxide group between Si and 
the alkoxy group (hereinafter may be referred to simply as an alkoxy 
group-containing silicone resin) makes it possible to achieve the 
objective. 
That is, the present invention provides a non-toxic antifouling coating 
composition containing 50 to 99 percent by weight as the resin solid 
content of (A) a reaction-curable silicone resin composition and 1 to 50 
percent by weight as the solid content of (B) a silicone resin having an 
average molecular weight of 250 to 30,000, a viscosity of 20 to 50,000 
centistokes and an alkoxy group at its molecular terminal, and represented 
by the general formula (I): 
##EQU2## 
where R is a hydrogen atom, an alkyl group having 1-10 carbon atoms, aryl 
group or aralkyl group, R.sup.1 is a bivalent aliphatic hydrocarbon group 
having 1-10 carbon atoms, which may be bonded directly or through an ether 
group, ester group or --NH--group, R.sup.2 is a lower alkyl group having 
1-6 carbon atoms, X and Y are represented respectively as 
0.01.ltoreq.X&lt;4.0, 0.01.ltoreq.Y.ltoreq.4.0 and 0.02.ltoreq.X+Y&lt;4. 
Typical components of the non-toxic antifouling coating composition of the 
present invention are explained more in detail as follows. 
REACTION-CURABLE SILICONE RESIN 
Composition (A) 
The reaction-curable silicone resin composition used in the present 
invention comprises, as the major component, an organopolysiloxane which 
has a siloxane bond and is chemically reacted and cured at a room 
temperature lower than about 80.degree. C., by heating at about 80.degree. 
C. or higher, or by the irradiation of ultraviolet light or electron rays. 
The organopolysiloxane has such a structure that a curably reactive 
functional group and organic group are bonded directly to Si atom. 
Examples of the curably reactive functional group may include an hydroxyl 
group and a alkoxy group having 1 to 5 carbon atoms. Examples of the 
organic group may include a methyl group, ethyl group, vinyl group, 
haloalkyl group, phenyl group, etc. Further, to the organopolysiloxane may 
be added at least one selected from polyfunctional silane compounds which 
have a hydrolyzable group such as an cetoxy group, ketoxime group or the 
like as a crosslinking agent, and at least one selected from a group which 
consists of the octylates and naphthenates of zinc, iron, cobalt, tin 
etc., peroxides, organic amines, etc. as a curing catalyst respectively. 
The above silicone resin composition (A) is cured at room temperature or 
by heating according to hydrolyzation, dealcoholyzation, deacetification, 
dehydroxyamination, etc. The use of the organopolysiloxane having vinyl 
group makes possible curing by irradiation of electron rays or ultraviolet 
light. It is necessary for the irradiation of ultraviolet light to add a 
photosensitizer. Specific examples of a reaction-curable silicone resin 
composition containing organopolysiloxane as a major component include 
KE42, KE44 and KE45S (trade names, all marketed by Shin-Etsu Chemical Co., 
Ltd., a silicone varnish, one-pack type RTV rubber, reaction-curable at 
room temperature), KR2706 (trade name, marketed by Shin-Etsu Chemical Co., 
Ltd., a silicone varnish), SE9140 Dispersion (SE9140: trade name, one-pack 
type cold curing silicone coating composition, marketed by Toray Silicone 
Co., Ltd.), SH237 Dispersion (SH237: trade name, Silicone Release Agent, 
marketed by Toray Silicone Co., Ltd.), Pelgan.RTM. C (trademark, cold 
curing silicone varnish, marketed by Dow Corning K.K.), and FS XR-2622 
(trade name, cold curing elastplastic silicone varnish, marketed by Dow 
Corning K.K.). 
Alkoxy group-containing silicone resin (B) 
The alkoxy group-containing silicone resin used in the present invention is 
a silicone resin having an average molecular weight of 250 to 30,000, a 
viscosity of 20 to 50,000 centistokes and an alkoxy group, preferably a 
methoxy group and an ethoxy group at its molecular terminal, and 
represented by the general formula (I): 
##EQU3## 
where R is a hydrogen atom, an alkyl group having 1-10 carbon atoms, an 
aryl group or aralkyl group, R.sup.1 is a bivalent aliphatic hydrocarbon 
group having 1-10 carbon atoms, which may be bonded directly or through an 
ether group, ester group or --NH--group, R.sup.2 is a lower alkyl group 
having 1-6 carbon atoms, X and Y are represented respectively as 
0.01.ltoreq.X&lt;4.0, 0.01.ltoreq.Y&lt;4.0 and 0.02.ltoreq.X+Y&lt;4. 
Examples of the alkoxy group-containing silicone resin include KF351 (trade 
name, marketed by Shin-Etsu Chemical Co., Ltd., polyether modified 
silicone oil, viscosity: 100 cp at 25.degree. C.), KF353 (trade name, 
marketed by Shin-Etsu Chemical Co., Ltd., polyether modified silicone oil, 
viscosity: 400 cp at 25.degree. C.), SH3749 (viscosity: 1300 cp), BX16-034 
(viscosity: 630 cp) and SF8410 (viscosity: 2900), all marketed by Toray 
Silicone Co., Ltd., polyether modified silicone oil, and ISI4452 (trade 
name, marketed by Toshiba Silicone Co., Ltd., silicone-polyether 
copolymer, viscosity: 1,000 cp at 25.degree. C.). 
The alkoxy group-containing silicone resin used in the present invention 
may have a mean molecular weight of 250 to 30,000, preferably 1,000 to 
20,000. When the molecular weight is less than 250, the resulting film 
shows poor drying characteristics, and when the molecular weight is more 
than 30,000, the exudation effect of the alkoxy group-containing silicone 
resin to the surface is not realized, resulting in poor antifouling 
properties. 
When the viscosity of the alkoxy group-containing silicone resin is lower 
than 20 centistokes, it may be exuded to the surface, but could not retain 
itself thereon, thereby making it impossible to obtain the intended 
antifouling performance. On the other hand, when the viscosity is higher 
than 50,000 centistokes, its exudation to the surface becomes impossible, 
thereby making it impossible to obtain the intended antifouling 
performance. 
The alkoxy group-containing silicone resin contains an alkoxy group 
preferably in an amount of 0.1 to 15 percent by weight. 
The alkoxy group-containing silicone resin is formulated in the 
aforementioned proportion, i.e. in an amount of 1 to 50 percent by weight, 
preferably 2 to 30 percent by weight with the reaction-curable silicone 
resin composition (A), and the resulting cured film obtained by curing at 
room temperature, heat curing or irradiation of actinic rays shows 
excellent antifouling properties. When the amount of the alkoxy 
group-containing silicone resin is less than 1 percent by weight, the 
antifouling effect is reduced. On the other hand, when more than 50 
percent by weight, the curing properties of the resulting film becomes 
poor, thereby making it impossible to obtain a coated film which has the 
satisfactory durability required for the antifouling coated film. 
The non-toxic antifouling coating composition may include, when needed, 
chlorinated paraffin, solid paraffin, liquid paraffin, dimethylsiloxane, 
methylphenylsiloxane, etc. in an amount of about 10 parts by weight or 
less per 100 parts by weight of the coating composition, and further may 
include pigments such as extender pigments, color pigments, 
corrosion-resistant pigments and the like, plasticizers, anti-sag agents, 
antifouling agents, etc. depending on the film performance required. 
The present invention makes it possible to provide a non-toxic antifouling 
coating composition capable of forming a coated film which is non-toxic 
and shows excellent antifouling properties over a long period of time. 
The reasons for the above results as provided by the present invention are 
explained more in detail as follows. 
It has been proposed by R.E. Baier that a substance which has a micromosaic 
structure has the effect of inhibiting adsorption of protein, adhesion of 
bacteria, and growth of diatom and large-sized living things on the 
surface of the above substance respectively. 
The alkoxy group-containing silicone resin used in the present invention, 
as its constitution, has a polysiloxane bond, has an alkoxy group at its 
molecular terminal through an ethylene oxide group or propylene oxide 
group between Si and the alkoxy group, and has both a hydrophobic group 
and hydrophilic group in the molecule. Previously, the present inventors 
proposed that a combination of a hydroxyl group- or polar group-containing 
silicone resin with a reaction-curable silicone resin makes it possible to 
form the above micromosaic structure, and found that the above micromosaic 
structure was actually formed by use of a phase-contrast microscope and 
showed significant effects on markedly inhibiting adsorption of protein to 
its surface and on inhibiting adhesion of bacteria, diatom and large-sized 
living things to its surface. Now, however, it has been found that the 
non-toxic antifouling coating composition which contains the alkoxy 
group-containing silicone resin in the present invention shows a finer and 
more uniform hydrophilic/hydrophobic or hydrophobic/hydrophobic 
micromosaic structure, and the use of the coating composition of the 
present invention provides such effects as to even further inhibit the 
adsorption of protein to its surface, and makes it possible to inhibit the 
adhesion of the above living things to its surface for a long period of 
time. 
Thus, it is considered that the antifouling coating composition of the 
present invention is capable of maintaining excellent antifouling 
properties for a long period of time without using toxic antifouling 
agents. 
The present invention is explained more in detail by the following Examples 
and Comparative Examples, in which "part" means "part by weight" unless 
otherwise expressed. The Examples are not to be construed as limiting the 
scope of the present invention.

EXAMPLES 1-3 AND COMATIVE EXAMPLES 1-3 
Non-toxic antifouling coating compositions were prepared according to the 
formulation shown in Table 1 respectively. 
TABLE-1 
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Comparative 
Formulation 
Examples Examples 
(parts) 1 2 3 1 2 3 
______________________________________ 
KE42 (*1) 
40 40 
KE44 (*2) 25 35 
SH237 (*3) 35 35 
KF351 (*4) 
10 
BX16-034 25 
(*5) 
ISI4452 (*6) 15 
SF8428 (*7) 10 
ISI4700 (*8) 15 
XI42-411 (*9) 15 
Aerosil .RTM. 
0.5 0.5 0.5 0.5 0.5 0.5 
#200 (*10) 
Xylene 49.5 49.5 49.5 49.5 49.5 49.5 
Total 100.0 100.0 100.0 100.0 100.0 100.0 
______________________________________ 
In Table-1, (*1)-(*3) mean trade names of organopolysiloxane as above 
mentioned respectively, (*4)-(*6) means trade names of alkoxy 
group-containing silicone resins as above mentioned respectively, (*7) 
means a trade name of alcohol-modified silicone oil (viscosity: 130 cp) 
marketed by Toray Silicon Co., Ltd., (*8) means a trade name of 
amino-modified silicone oil (viscosity: 50 cp at 25.degree. C.) marketed 
by Toshiba Silicone Co., Ltd., (*9) means a trade name of carboxyl 
modified silicone oil (viscosity: 100 cp at 25.degree. C.) prepared by way 
of trial, i.e., experimental basis, by Toshiba Silicone Co., Ltd., and 
(*10) means a trademark of an extremely pure amorphous silica marketed by 
Nihon Aerosil Co., Ltd. 
PERFORMANCE TEST RESULTS 
A zinc epoxy shop primer was coated onto a sandblasted steel sheet of 100 
mm.times.300 mm.times.2 mm to a dry film thickness of 15 .mu.m, and an 
epoxy anticorrosive coating composition was coated thereonto to a dry film 
thickness of 200 .mu.m to obtain a coated steel sheet, followed by the 
antifouling coating compositions obtained in the Examples and Comparative 
Examples which were coated onto the coated steel sheet to a dry film 
thickness of 100 .mu.m respectively to obtain coated test sheets. The 
coated test sheets were dried for 7 days at room temperature, followed by 
being dipped into seawater in Toba Bay, Mie-ken, Japan for 24 months to 
evaluate antifouling properties. The results ar shown in Table-2, in which 
"%" means a percentage of an area in which adhesion takes place relative 
to a total area of the coated test sheet. 
TABLE-2 
______________________________________ 
Antifouling properties 
in seawater 
Adhesion of 
Adhesion of 
green laver 
barnacle 
(%) (%) 
______________________________________ 
Examples 1 0 0 
Examples 2 0 0 
Examples 3 0 0 
Comparative 
Examples 
1 10 5 
2 20 15 
3 10 15 
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