Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-09-11
2002-06-25
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S122000, C525S360000, C525S376000, C525S420000, C525S437000, C525S453000, C525S454000, C527S312000
Reexamination Certificate
active
06410622
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a process and product for preventing fouling organisms in marine environments, and more particularly to such a process and product which uses polymer-bound nitric oxide
itric oxide-releasing compositions.
Marine fouling on ships, marine and sessile structures has been a problem for countless years. Shells and algae such as barnacles, oysters, mussels, hydroids, tube worms, bryozoans, tunicates, sea weeds and the like settle to and propagate on untreated: ship hulls, fishing nets, in-sea-water facilities (e.g. buoys), in-water structures (e.g. part of dam facilities), feed pipes for cooling water for condensers used in steam power plants or for heat exchangers used in petrochemical plants, etc. (these parts and facilities are in constant contact with water), fishing nets for cultivation or for fixed net fishing, etc. These fouling organisms invite increased resistance of water supply and reduced thermal conductivity, and bring about disadvantages such as reduced function of the facility and the like. In fishing nets, the settlement of the above-mentioned organisms causes stopping-up of meshes, and resultant oxygen shortage, scratching of fish (this reduces the commercial value of fish), and infection of fish with diseases caused by microbes, etc.
Thus, there has been a need to prevent fouling organisms, namely to prevent settlement and propagation of such seawater or pure water fouling organisms to and on ship hulls, fishing nets, in-sea-water facilities (e.g. buoys), in-water structures (e.g. part of dam facilities), feed pipes for cooling water for condensers used in steam power plants or for heat exchangers used in petrochemical plants, etc. A specific fouling organism gaining attention in more recent years has been the zebra mussel.
The marine fouling problem has been recently addressed primarily by the use of certain coatings containing biocides that are toxic to marine organisms. These conventional coatings leached biocides out of the coating when in seawater.
Self-polishing antifouling coatings have been used. These coatings are based on polymers of tributyltin methacrylate, methyl methacrylate, and film softening monomers such as 2-ethylhexyl acrylate. An organotin polymer acts as the paint binder. All such paints also contain a toxicant additive such as cuprous oxide or a triorganotin compound. In addition, the usual paint additives such as pigments, thixotropic agents, etc. may also be present. In normally alkaline seawater, the polymeric organotin binder is gradually hydrolyzed, and the tributyltin is liberated in a form that is an active antifoulant. The hydrolyzed polymer formed is water-soluble or water-swellable and is easily eroded off the surface by moving seawater, exposing a fresh surface of paint.
The major advantage of these systems is that, unlike leaching paints, toxicant release is linear with time, and all of the toxicant present is utilized over the lifetime of the paint. Furthermore, there is no need to remove the residues of an old self-polishing paint system prior to repainting, since the composition of the residue is essentially the same as it was when originally applied, unlike conventional antifouling paints which leave a weak, leached-out matrix of binder on the ships' hull at the end of their lifetime. An additional advantage claimed for such systems is a reduction in hull surface roughness with time as a consequence of erosion of the paint film. This roughness reduction translates to fuel savings for the ship operator.
Sea-going vessels usually have between 2 and 4 coats of antifouling paint, each coat of 100 microns film thickness, applied to the hull. This coating, of 200 to 400 microns total film thickness, is expected to last for about five years.
A marine antifoulant coating should preferably meet some criteria in order to be commercially acceptable, such as the following. The polymer should be preferably soluble in a paint media for easy application. The polymer solution should preferably have good film-forming properties. The film coating preferably should have good adhesion to the ship's surface and be flexible; and the film preferably should undergo hydrolysis only at the coating surface. This permits the controlled release of the metal. The remaining paint surface becomes susceptible to the moving seawater and is eroded. This mechanism is known as “self-polishing,” and a marked improvement in the ship's fuel efficiency is observed. The polymer preferably should also have controlled release characteristics.
U.S. Pat. No. 5,637,745 issued to Silverman et al. discloses various organometallic compounds and polymers made therefrom for antifouling purposes; which patent is incorporated herein by reference in its entirety.
Although antifouling agents containing an organotin compound as described above have been effective, there has recently arisen substantial social concern that the organotin compounds themselves are polluting rivers, lakes, oceans and the like; and further, that the organotin compounds cause harm to human bodies via fish. Hence, a regulation has been established regarding the use of organotin compounds, and the use and production of organotin compounds are under mandatory control.
Meanwhile, organic compounds other than organotin compounds have been studied as antifouling agents. For example, the compound capsaicin (a colorless irritant phenolic amide found in hot peppers), has shown some promise as an antifouling agent. However, preventative agents for fouling organisms containing conventional organic compounds have not provided antifouling properties as effective as desired. U.S. Pat. No. 5,603,755 issued to Okada et al. discloses various non-organotin compounds for antifouling purposes; which patent is incorporated herein by reference in its entirety.
Thus, it is an object of the present invention to provide a process and product for preventing fouling organisms in marine environments. It is a further object of the present invention to provide a preventative agent for fouling organisms, containing as an effective ingredient an organic compound other than organotin compounds, which preventative agent advantageously is acceptably safe for the environment and humans, and exhibits a relatively high antifouling effect at a relatively low dosage. Yet further, it is an object of the present invention to provide such a preventative agent which may be used in combination with known and commonly used toxins such as organotin compounds, thereby advantageously rendering the toxins more effective at lower concentrations, thus minimizing any environmental harm caused by the toxins.
SUMMARY OF THE INVENTION
The present invention addresses and solves the problems/drawbacks enumerated above, and encompasses other features and advantages as well. The present invention comprises a method of preventing fouling organisms in marine environments. The method comprises the step of introducing into the marine environment in a predetermined form and in a sufficient amount an antifouling composition having as its effective ingredient a nitric oxide-releasing functional group of the diazeniumdiolate structure:
whereupon nitric oxide is controllably released into the marine environment to prevent at least one of the fouling organisms' propagation, ability to attach, and ability to function.
An antifouling composition according to the present invention consists essentially of an antifouling-acceptable carrier and a coprecipitation product of a polymer selected from the group consisting of polyolefins, polyethers, polyesters, polyamides, polyurethanes, peptides, and starburst dendrimers, and an organic compound containing the nitric oxide-releasing functional group. The nitric oxide-releasing functional group may be of the formula:
wherein b and d are the same or different and may be zero or one; R
1
, R
2
, R
3
, R
4
and R
5
are the same or different and may be hydrogen, C
3-8
cycloalkyl, C
1-12
straight or branched chain alkyl, benzyl, benzoyl, phthalo
Dierker & Glassmeyer
Szekely Peter
LandOfFree
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