NO139964B - COATING AGENT FOR COUNTERFEIT OF MARINE GROWTH, CONTAINING A TRIAL COOLTIN PHENOXIDE - Google Patents

Description

The present invention relates to improved antifouling coatings, where the active poison is an organotin compound which does not interfere with the vulcanization of the liquid hydrocarbon rubber which forms the film-forming component of the coating.

Numerous triorganotin compounds have been incorporated into both natural and synthetic rubbers in an attempt to achieve a gradual release of the organotin compound into the surrounding water over long periods of time for the purpose of killing or repelling fouling organisms and disease-carrying organisms in or immediately around the area the rubber. US-PS 3,417,181 describes a number of tripropyl and tributyltin derivatives which are effective for such use, including chlorides, oxides, fluorides, carboxylates and resinates. The oxides are particularly preferred. All of these compounds can be useful when incorporated into compositions containing solid gums, but many of them, including bis-(tri-n-butyltin)oxide are unsuitable for use with recently developed synthetic gums which are low molecular weight and liquid by - supply temperature. It is e.g. demonstrated that bis(tri-n-butyltin) oxide interferes with the vulcanization or curing, i.e. the cross-linking of the rubber, which is necessary to obtain the desired properties of the finished product. The liquid gums have significant advantages over their solid homologues with a higher molecular weight. They can be more easily incorporated into relatively low-viscosity coatings that Jean is applied using common techniques, including brush application and spraying. The solid rubbers, which are usually used in the form of sheets, are attached by means of adhesive to the surface to be protected, e.g. a boat's hull or piers. The problems that arise when such a product is to be applied to large or irregular surfaces can be quite enormous.

Particularly preferred liquid gums are those copolymers of isobutene with small amounts of isoprene which have an average molecular weight of approx. 32,000 and on average contains approx. 7 carbon-carbon double bonds per molecule.

It has surprisingly been found that certain organotin compounds effectively kill and/or repel weevils and other organisms responsible for fouling, without interfering with the vulcanization of liquid gums as is the case with other compounds. spésiéft bis (triorganotin)-

The object of the present invention is thus a liquid stain-<ldél'''iB'6m'' '-'which binder contains a vulcanizable hydrocarbon rubber with an average of at least one carbon-carbon double bond per molecule, a vulcanization catalyst for the rubber and a triorganotin compound, characterized in that it contains a liquid isobutene/iso<p>reh copolymer (butyl rubber) bg 5-15 weight percent, calculated on the total weight of the coating agent, of at least one liquid triorganotin compound with the general formula

where each R is an alkyl radical with 1-8 carbon atoms, X is any substituent selected from the group consisting of halogen and phenyl/and n' is an entire number from 0' to 5.

The coating agents according to the present invention can be vulcanized (hereinafter sometimes called "cured" or "cross-linked") to solid products using a wide variety of catalysts. The nature and concentration of the selected catalyst is determined at least in part by the desired vulcanization sering temperature bg -velocity One preferred catalyst for use at ambient temperatures is p-quinone dibxime, which is used in combination with a suitable oxidizing agent such as lead dioxide, manganese dioxide or organic peroxides, for example t-butylperbehzoate and kdboltirapthenate. The particle size of the oxidase inhibitor is shown to have an effect on the vulcanization rate.

As the liquid rubber will begin to vulcanize in the presence of a combination of catalyst and oxidizing agent, it may be desirable to add the oxidizing agent just before the coating agent is applied. When lead oxide is used as an oxidising agent, it has been found to be appropriate to incorporate this material into a paste which also contains one fatty acid such as e.g. stearic acid and a phthalate ester which: is used as a plasticizer.

The correct concentrations of catalyst and oxidizing agent are determined by the desired vulcanization rate. Generally, the concentration of catalyst will lie between 1 and 10%, calculated on the weight of the liquid rubber, because the lead dioxide oxidizing agent will be present in an amount of between 2 and 5 times the weight of the catalyst.

In addition to the liquid rubber, the trialkyltin compound and the catalyst, the coating agent may also contain other ingredients to facilitate the application of the coating agent or to modify one or more of the properties of the final product. The optional ingredients include organic solvents, fillers, dyes and pigments. t -.s

Some preferred coating agents are described in the following examples., All;:parts. are parts by weight unless otherwise stated.

Example 1 'ov.---;\ mot. >.■ :*^\ tv."*

To 30 parts of a mixture containing 360 parts of

a liquid isobutene/isoprene kbpolymer (butyl rubber, e.g. 4

"LM Butyl 504"), 480 parts of xylene, 2!,'4 parts of p^kihondioxime bg 3 parts of a standard vulcanization accelerator comprising a mixture of N,N-dimethylformamide and glacial acetic acid in a weight ratio of 1:1, was put there 1 ) 3.3 parts of a paste containing 3.25 parts lead dioxide, 0.33 parts stearic acid bg 2.92 parts dibutyl phthalate and 2) 3.3 parts of a fTyténdé brganotin compound.

The resulting coatings were 'thoroughly mixed for a few minutes and then applied as films to glass plates, the coated plates were allowed to stand' for approx. 16-20 hours at ambient temperature, after which the films were examined to determine the degree of vulcanization that had taken place/ The results of the examination are summarized in the following table. 'x'

Example 2

Comparison of the effectiveness of bis(tri-n-butyltin) oxide and tri-n-butyltin-2,4,6-trichlorophenate for curing liquid rubber compositions.

The paste described in Example 1 and 10 parts of either bis(tri-n-butyltin)oxide or tri-n-butyltin-2,4,6-trichlorophenate was added to 90 parts of a mixture of 600 parts of a xylene solution containing 60% by weight of that isobutene/

isoprene copolymer described in Example 1, 240 parts of xylene, 24 parts of p-quinone dioxime and 3 parts of a mixture of N,N-dimethylformamide and acetic acid in a weight ratio of 1:1. A third together-. sentence was prepared without any tin compound. Each of the compositions was applied to steel plates using a paint brush. After approx. After 24 hours of exposure in air at ambient temperature, the compositions containing no tin compound and the trichlorophenate appeared to be properly and evenly cured, being dry and only slightly "tacky" to the touch. The composition containing the bis(tri-n-butyltin)oxide was significantly more "sticky" than the other two samples and had a film

of a brown liquid above the rubber layer, showing that at least a portion of the tin compound had been secreted from the surface of the liquid rubber.

Example 3

Production and evaluation of antifouling coatings containing liquid gums and triorganotin compounds.

A composition was prepared by thorough mixing of

the following components:

1) 100 parts of a 60% by weight liquid isobutene/isoprene copolymer solution in xylene

2) 40 parts xylene

3) 4 parts p-quinone dioxime

90 parts of the resulting mixture was combined with 1) 10 parts of carbon black, 2) 7 parts of a paste containing 3.25

parts lead dioxide, 0.33 parts stearic acid and 2.92 parts dibutyl phthalate and 3) 10 parts tri-n-butyltin pentachlorophenate.

The above-mentioned coating agent was evaluated with regard to antifouling properties by applying two coats (each of between 51 and 64 pm) of the agent to both main rafts of a 15 x 40 cm glass fiber reinforced polyester panel which had previously been sandblasted to obtain a rough surface. After curing the coating, the plates were submerged in Biscayne Bay at Miami Beach in Florida. The conditions in this area contribute particularly to the development of fouling organisms. The panels were attached to a raft in such a way that only the upper third of each panel was above the water line at any time.

The panels were taken up at monthly intervals, inspected/ and the anti-fouling properties assessed by observing the number of tendrils present. At the end of a 5 month period, the most vegetated surface of the panel showed only 7 vine footings. In comparison, a panel coated with a similar composition, except that the organotin compound was — absent, showed 79 tendrils after a stay of 1 month and over 100 after a stay of 3 months.

Claims (2)

1. Liquid coating agent which as a binder contains a vulcanizable hydrocarbon rubber with an average of at least one carbon-carbon double bond per molecule, a vulcanization catalyst for the rubber and a triorganotin compound, characterized in that it contains a liquid isobutene/isoprene copolymer (butyl rubber) and 5-15 percent by weight, calculated on the total weight of the coating agent, of at least one liquid triorganotin compound of the general formula where each R is an alkyl radical with 1-8 carbon atoms, X is a possible substituent selected from the group consisting of halogen and phenyl/ and n is an integer from 0 to 5. 2. Coating agent as stated in claim 1, characterized in that each R is an n-butyl radical and X is chlorine.