Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-12-27
2002-10-01
Sanders, Kriellion A. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C523S122000, C526S279000
Reexamination Certificate
active
06458878
ABSTRACT:
TECHNICAL FIELD
The present invention relates to silyl (meth)acrylate copolymers, processes for preparing the same, antifouling paint compositions containing the silyl (meth)acrylate copolymers, antifouling coating films formed from the antifouling paint compositions, antifouling methods using the antifouling paint compositions, and hulls or underwater structures coated with the coating films.
More particularly, the invention relates to silyl (meth)acrylate copolymers which can produce antifouling paints capable of forming antifouling coating films which hardly suffer from occurrence of cracks, have excellent adhesive strength and thereby hardly suffer from peeling, can be favorably controlled in the hydrolysis rate, and are excellent in antifouling performance (antifouling activities), antifouling properties, particularly antifouling properties in a highly fouling environment, and long-term antifouling properties. The invention also relates to processes for preparing such copolymers, antifouling paint compositions capable of forming antifouling coating films having the above properties, antifouling coating films formed from the antifouling paint compositions, antifouling methods using the antifouling paint compositions, and hulls or underwater structures coated with the coating films.
BACKGROUND ART
Ships' bottoms, underwater structures, fishing nets, etc. sometimes have bad appearances and lose their functions, when they are exposed to water for a long time and various aquatic organisms, for example, animals such as oysters, hard-shell mussels and barnacles, plants such as laver, and aquatic bacteria adhere and propagate thereon.
Especially when such aquatic organisms adhere and propagate on a ship's bottom, the surface roughness of the whole ship may be increased to induce decrease of velocity of the ship or increase of fuel consumption. Further, removal of such aquatic organisms from the ship's bottom needs much labor and a long period of working time. In addition, if bacteria adhere and propagate on an underwater structure and slime (sludge-like substance) further adheres thereto to bring about decomposition of the bacteria, or if large-sized organisms adhere and propagate on an underwater structure such as a steel structure to damage anticorrosive coating films of the underwater structure, the strength or the function of the underwater structure may be lowered to thereby extremely shorten the lifetime of the underwater structure.
In order to prevent such problems, ships' bottoms have been hitherto coated with antifouling paints of excellent antifouling properties, for example, a paint containing a copolymer of tributyltin methacrylate and methyl methacrylate or the like and cuprous oxide (Cu
2
O). The copolymer contained in this antifouling paint is hydrolyzed in seawater to release an organotin compound such as bistributyltin oxide (tributyltin ether, Bu
3
Sn—O—SnBu
3
(Bu: butyl group)) or tributyltin halide (BU
3
SnX (X: halogen atom)) and exerts an antifouling effect, and besides the hydrolyzed copolymer itself becomes water-soluble and is dissolved in seawater. That is, this antifouling paint is a “hydrolyzable self-polishing paint”, so that no resin residue remains on the coated surface of the ship's bottom, and the surface can be always kept active.
Such organotin compounds, however, are strongly toxic, and there are fears of marine pollution, occurrence of malformed fish or malformed shellfish and evil influences on the biosystem due to the food chain. For this reason, development of tin-free antifouling paints substitutable for the conventional paints has been desired.
The tin-free antifouling paints are, for example, silyl ester antifouling paints described in (1) Japanese Japanese Patent Laid-Open Publication No. 264169/1992 and (3) Japanese Patent Laid-Open Publication No. 264168/1992. These antifouling paints, however, have problems of poor antifouling properties and occurrence of cracking or peeling, as taught by (4) Japanese Patent Laid-Open Publication No. 157941/1994 and (5) Japanese Patent Laid-Open Publication No. 157940/1994.
In (6) Japanese Patent Laid-Open Publication No. 196869/1990, an antifouling paint containing a chemically modified acid functional copolymer (A), which is obtained by copolymerizing trimethylsilyl methacrylate, ethyl methacrylate and methoxyethyl acrylate in the presence of an azo polymerization initiator and contains a carboxylic acid group blocked by a trimethylsilyl group, and a compound (B) of a polyvalent cation is taught. This antifouling paint, however, has a problem that a coating film obtained from the antifouling paint is not satisfactory in the crack resistance.
In (7) National Publication No. 500452/1985 of International Patent Application and Japanese Patent Laid-Open Publication No. 215780/1988, a resin for an antifouling paint, which is obtained by copolymerizing a vinyl monomer having an organosilyl group such as a trialkylsilyl ester of (meth)acrylic acid with another vinyl monomer and has a number-average molecular weight of 3,000 to 40,000, is described. It is also described that an organic water binder such as trimethyl orthoformate, an antifouling agent such as cuprous oxide and a pigment such as red iron oxide can be further added. This resin for an antifouling paint, however, has problems that the resin is liable to be gelatinized when stored and a coating film formed from the antifouling paint has poor crack resistance and peel resistance, as described in (5) Japanese Patent Laid-Open Publication No. 157940/1994.
In Japanese Patent Publication No. 32433/1993 corresponding to the above-mentioned publication (7) (National Publication No. 500452/1985 of International Patent Application), an antifouling paint comprising (a) a toxic substance and (b) a polymer binder which has a recurring unit represented by the formula (—CH
2
—CXCOOR)—(B)— (X is H or CH
3
, R is SiR′
3
or Si(OR′)
3
, R′ is an alkyl group or the like, and B is a residual group of an ethylenically unsaturated monomer) and has a specific hydrolysis rate is disclosed. It is also described that a solvent, a water-sensitive pigment component, an inert pigment, a filler and a retarder can be further introduced. The coating film obtained from the antifouling paint described in this publication, however, has a problem of poor crack resistance.
In (8) Japanese Patent Laid-Open Publication No. 18216/1995, there is disclosed a paint composition which contains, as its major components, (A) a polymer of an organosilicon-containing monomer A having an organosilicon triester group represented by the formula (I) —COO—SiR
1
R
2
R
3
(R
1
to R
3
are each an alkyl group of 1 to 18 carbon atoms or the like) in a molecule and (B) copper or a copper compound and further contains, as an essential component other than the components (A) and (B), an alkoxy group-containing silicon compound represented by the following formula (C):
wherein R
4
to R
6
are each a hydrogen atom, an alkoxy group of 1 to 18 carbon atoms, a cycloalkoxy group or the like, R
7
is an alkyl group of 1 to 18 carbon atoms or the like, and n is an integer of 1 to 3.
In the above publication, it is also described that a copolymer AB of the monomer A having a group represented by the formula (I) and a vinyl monomer B copolymerizable with the monomer A may be contained. Further, (meth)acrylic esters such as methyl (meth)acrylate, ethyl (meth)acrylate and dimethylaminoethyl (meth)acrylate are given as examples of the monomer B.
The coating film obtained from the paint composition described in the above publication, however, has a problem that a coating film obtained from the paint composition is poor in the crack resistance and the antifouling properties, particularly antifouling properties in a highly fouling environment. The term “highly fouling environment” indicates, for example, a sea area rich in nutritive such as inland sea or a state where a ship or structure is allowed to stand in such a sea area or a ship frequently repeats running and stoppi
Arimura Hidetaka
Hamazu Fumio
Hikiji Yasuto
Hiyoshi Satoshi
Kozono Yukio
Chuogoku Marine Paints, Ltd.
Sanders Kriellion A.
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