Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-11-02
2001-01-23
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S292100, C526S295000, C526S318400, C526S318440, C526S328500, C526S329400
Reexamination Certificate
active
06177530
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an antifouling paint composition. More particularly, it relates to an antifouling paint composition which is capable of inhibiting attachment and accumulation of marine organisms and seaweeds on the underwater structures, fishing nets and the ship bottom.
BACKGROUND ART
The submerged portions of the ships and marine structures are provided with an antifouling coating containing rosin or organic tin for the purpose of preventing corrosion or the drop of cruising speed of the ships due to attachment of marine creatures such as barnacles, teredos, and algae. Such an antifouling coating is also provided on the nets used at the nurseries of fishes or marine products for the purpose of preventing fatal effect on the reared fishes and shellfishes by the attachment of marine organisms on the nets.
The antifouling effect of these antifouling coatings is demonstrated as the rosin and antifouling substance(s) contained in the coating are eluted into seawater. Therefore, when the coating is left immersed in seawater for a long period of time, the eluting substance is gradually decreased while the non-eluting matter is left in the coating, and at the same time the coating surface becomes jagged, which tends to excessively reduce the effect of the coating to prevent attachment and accumulation of marine organisms. In the case of organotin-containing self polishing type paint, the coating surface is gradually dissolved away to constantly renew the surface so that the antifouling substance will be always kept exposed on the coating surface to allow long-time retention of its antifouling effect. This type of antifouling paint, however, has a possibility to give baneful influence to fishes and shellfishes because of strong toxicity of organic tin contained therein. Thus, request is intensifying in the industry for the development of a self polishing type antifouling paint composition which is low in toxicity and capable of exhibiting its antifouling effect in the sea for a prolonged period of time. Many studies have been made on the self polishing type paints free of organic tin. For example, JP-A-62-57464 and JP-A-62-84168 describe the antifouling paint compositions using the copolymers having a metal-containing group at the end of the side chain. Also, JP-A-5-171066 discloses an antifouling paint composition containing a copolymer comprising a metal-containing monomer having 2 to 3 double bonds, as a vehicle.
However, the antifouling paints using metal-containing copolymers such as described in JP-A-62-57464 and JP-A-62-84168 mentioned above are reduced in their self polishing action with time, so that their antifouling effect can hardly last for a long period of time. If the metal content per polymer molecular weight is increased for improving the self polishing characteristics of these antifouling paints, the formed coating becomes hard and frail and tends to develop cracks or exfoliate.
On the other hand, the antifouling paint using a copolymer such as described in JP-A-5-171066, although capable of maintaining its self polishing action for a long period of time tends to have an insufficient rate of consumption of the coating, hence is not necessarily satisfactory in long-time antifouling effect of coating. Also, the foamed coating tends to become hard and fragil with the lapse of time, and further this type of paint is unsatisfactory in its recoatability on the old coating formed from an organotin-based paint and so on, so that the recoating film tends to crack or exfoliate.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a self polishing type antifouling paint composition which is capable of displaying an excellent antifouling effect in seawater for a prolonged period of time and also shows excellent crack resistance and recoating properties on the old coating formed from an organotin-based paint and so on.
As a result of extensive studies on the subject matter, the present inventors found that an antifouling paint containing as vehicle a metal-containing copolymer consisting of specific polymerizable monomers is capable of maintianing an excellent antifouling effect in seawater for a long period of time and also has excellent recoatability on the old coating formed from an organotin-based paint and so on.
The present invention provides an antifouling paint composition containing as vehicle a copolymer from a mixture of (a
1
) a metal-containing polymerizable monomer having two unsaturated groups and (a
2
) a metal-containing monomer represented by the following formula (I):
wherein R
1
represents a hydrogen atom or a methyl group; M represents Mg, Zn or Cu; and R
2
represents an organic acid residue.
The present invention also provide an antifouling paint composition containing as vehicle a copolymer from a mixture of (a) a metal-containing polymerizable monomer and (b) a polymerizable monomer represented by the following formula (II):
wherein R
3
represents a hydrogen atom or a methyl group; R
4
represents an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group or a phenyl group; and R
5
represents an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group or a phenyl group.
BEST MODE FOR CARRYING OUT THE INVENTION
The metal-containing polymerizable monomer (a) used as a constituent of the copolymer serving as a vehicle in the present invention is a substance which can afford a long-lasting high self polishing characteristics to the formed coating and also shows an excellent antifouling effect. Preferably, it is selected from the metal-containing polymerizable monomers (a
1
) having two unsatuated groups or the metal-containing polymerizable monomers (a
2
) represented by the formula (I) shown above.
Examples of the metal-containing polymerizable monomers (a
1
) having two unsaturated groups usable in the present invention include magnesium acrylate [(CH
2
═CHCOO)
2
Mg], magnesium methacrylate [CH
2
═C(CH
3
)COO]
2
Mg], zinc acrylate [(CH
2
═CHCOO)
2
Zn], zinc methacrylate [(CH
2
═C(CH
3
)COO)
2
Zn], copper acrylate [(CH
2
═CHCOO)
2
Cu], and copper methacrylate [(CH
2
═C(CH)COO
2
Cu]. These metal-containing polymerizable monomers (a
1
) may be used either singly or as a mixture of two or more of them as required. Zinc (meth)acrylate is especially preferred. When the term “(meth)acrylate” is used in the present specification, it means “acrylate or methacrylate”.
The metal-containing polymerizable monomers (a
2
) usable in the present invention are those represented by the above-shown formula (I). In the formula (I), R
1
represents a hydrogen atom or a methyl group; M represents Mg, Zn or Cu as a metal; and R
2
represents an organic acid residue. The organic acid residues include, for instance, those derived from monovalent organic acids such as monochloroacetic acid, monofluoroacetic acid, propionic acid, octylic acid, versatic acid, isostearic acid, palmitic acid, cresotinic acid, &agr;-naphthoic acid, &bgr;-naphthoic acid, benzoic acid, 2,4,5-trichlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, quinolinecarboxylic acid, nitrobenzoic acid, nitronaphthalenecarboxylic acid and pulvinic acid. Of these organic acid residues, the fatty acid type is especially preferred for the antifouling paints and can provide a coating which can stay free of cracks or exfoliation for a long period of time.
Examples of the metal-containing polymerizable monomers (a
2
) represented by the above formula (I) include, for example, magnesium monochloroacetate (meth)acrylate ((meth)acrylate meaning acrylate or methacrylate in the specification) zinc monochloroacetate (meth)acrylate, copper monochloroacetate (meth)acrylate, magnesium monofluoroacetate (meth)acrylate, zinc monofluoroacetate (meth)acrylate, copper monofluoroacetate (meth)acrylate, magnesium propionate (meth)acrylate, zinc propionate (meth)acrylate, copper propionate (meth)acrylate, magnesium octylate (meth)acrylate, zinc octylate (meth)acrylate, cop
Hotta Kazuhiko
Ito Masamitsu
Sugihara Mitsunori
Mitsubishi Rayon Co. Ltd.
Pezzuto Helen L.
Pillsbury Madison & Sutro LLP
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