JPS585988B2 - Composition that controls seawater-based fouling organisms and prevents copper corrosion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition containing dithiocarbamates and benzo)IJ azoles as active ingredients, which has both seawater-based fouling organism control and copper corrosion prevention effects.

In recent years, industrial use of seawater has been remarkable, and a large amount of seawater is used as cooling water on a one-time basis.

However, with the use of seawater, problems caused by seawater organisms such as mussels, barnacles, oysters, and water beetles have become a major problem.

On the other hand, the seawater near the coast is polluted1, especially the seawater taken from the bay often contains sulfides (compounds that liberate s'-ions).

In addition, sulfides may be generated in the sludge deposited in waterways due to the action of W salt-reducing bacteria.

Since many copper alloys are used in the main parts of seawater cooling systems, pitting corrosion caused by sulfides is particularly problematic.

Currently, ferrous sulfate is injected as a countermeasure against corrosion caused by these sulfides.

However, there is currently no satisfactory agent that prevents pitting corrosion caused by biological attachment and sulfide.

The inventor of this invention researched various drugs and found that
It has been found that a mixture of dithiocarbamates and pensito□lyazoles is extremely effective.

Among the two active ingredients used in this invention, dithiocarbamates are known to have anticorrosion properties for copper alloys and control effects on seawater-fouling organisms, but when actually added to a seawater cooling system.

The presence of even a small amount of sulfide in the seawater has the disadvantage that the sulfide accelerates pitting corrosion of copper alloys.

On the other hand, benzo)IJ azoles are used as anticorrosive agents and discoloration inhibitors for copper-based metals, but they are all used at high concentrations of 10 to 11,000 pp.

In fact, such concentrations in seawater cooling systems pose practical difficulties in terms of running costs and pollution.

Thus, mixing dithiocarbamates and benzotriazoles can prevent sulfide pitting corrosion on copper alloys at a flow rate of 1 to 2.5 m/sec by adding a very small amount to a seawater cooling system from a ship, and can also be used in sea waterways. It was discovered that biofouling can also be prevented.

That is, when actually using the pot, 0.1 to 0.5 ppm of dithiocarbamates and 0.01 to 0.5 ppm of benzotriazoles are used. By continuously adding O to a seawater cooling system at a low concentration of 5 ppm, it is possible to prevent the adhesion of seawater organisms and suppress pitting corrosion of copper alloys caused by sulfides.

Representative compounds of the dithiocarbamates of the present invention include sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate, sodium di-n-butyldithiocarbamate, sodium ethylphenyldithiocarbamate, and sodium diphenyldithiocarbamate.

Sodium N-piperidine dithiocarbamate.

Sodium N-pyrrolidine dithiocarbamate.

Examples include sodium N-cyclohexyldithiocarbamate, sodium dicyclohexyldithiocarbamate, and their potassium salts or ammonium salts.

Further, representative compounds of the benzotriazoles of this invention include 1,2,3-benzotriazole, 5-methylbenzotriazole, 5-ethylbenzotriazole,
5-n-propylbenzotriazole, 5-isobutylbenzotriazole 4-methylbenzotriazole, 5
Examples include -chlorobenzotriazole, 4-nitrobenzotriazole, 5-methoxybenzotriazole, and 5-hydroxybenzotriazole.

When adding these two types of compounds to seawater, they are appropriately diluted or dissolved or suspended in a suitable solvent such as water, methanol, dimethylformamide, acetone, xylene, etc. so as to be uniformly dispersed in seawater. If necessary, surfactants such as ethylene oxide-propylene oxide copolymer, alkylphenol-ethylene oxide adduct, polyethylene glycol alkyl phenyl ether, and poly-IJ ethylene glycol fatty acid ester can be added to formulate the composition.

Furthermore, if the benzotriazoles are made into basic salts, the two types of compounds can be formulated with water.

Also, one or more types of carbamates and benzo)IJ azoles may be used.

Next, examples of the present invention will be described.

Example: An experimental plant was constructed by connecting a circular waterway with a test net and an Alblack pipe (manufactured by Sumitomo Light Metals) with an inner diameter of 16 m, and seawater was flowed into the Alblack pipe at a flow rate of 2 to 2.5 m/s.
Water was passed through EC.

Then, each mixed drug was continuously injected, and 0.0% of soda sulfide was added from the front of the Alblack tube. Continuously simultaneously inject lppm of sulfide (
The degree of pitting corrosion caused by a compound that liberates S ions was investigated.

That is, a 40-day waterway experiment was conducted especially during the breeding season of mussels.

The effectiveness of controlling sessile organisms and inhibiting pitting corrosion was investigated.

Table 1 shows the degree of adhesion of mussels and Fujitbo and the degree and extent of pitting for the amount of each chemical added.

Note that both the dithiocarbamic acids and benzotriazoles were added continuously.

Claims (1)

[Claims] 1. A composition containing a dithiocarbamate salt and a benzotriazole as active ingredients, which has a seawater-based fouling organism control function and a copper corrosion prevention effect.