Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1982-04-05
1983-10-18
Jacobs, Lewis T.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
523512, C08L 6706
Patent
active
044106424
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to coating compositions for marine structures, to such structures and to methods of making them.
BACKGROUND OF THE INVENTION
The use of certain heavy metals, especially copper and copper alloys in antifouling coatings for ships and other marine structures is well known.
The use of gelcoats based on unsaturated polyester resins for GRP marine structures such as boats is also well known. However it is also well known that copper and its compounds are efficient inhibitors for unsaturated polyester resins, the effect first having been noticed when attempts were made to embed electrical windings in polyesters, and also having been noticed when GRP tubes were wound on brass mandrels and their inner surface was found to be discoloured and undercured.
This inhibiting effect was put to practical use by the use of small quantities (0.25-10 ppm Cu) of oil-soluble copper salts, such as the naphthenate, to improve the storage stability of liquid unsaturated polyester resins (G.B. Pat. No. 834,286).
Attempts to overcome the problem of preventing inhibition of cure in the presence of copper are illustrated by G.B. Pat. No. 967,921 which covers the addition of oxalic acid, by the use of hydroxy polycarboxylic acids such as tartaric acid to prevent inhibition in contact with copper (U.S. Pat. No. 2,566,739), and by G.B. Pat. No. 1,526,597 which covers the addition of benzotriazole to the resin to get a good bond between copper foil and glass-reinforced polyester in the manufacture of copper clad laminates for electrical purposes.
SUMMARY OF THE INVENTION
According to the invention, polyester and similarly curable resins are stable in the presence of 20-80% by weight of copper or copper alloy powder if they have an acid value below about 10 mg KOH/g, preferably not greater than 5.
In fact such compositions cure with a tack-free air surface. Such a tack-free surface is extremely surprising in view of the expected inhibiting effect of copper and in view of the fact that acid values of the order of 20-30 are much more normal. It is furthermore remarkable that when such normal resins are mixed with copper powder (which is suggested in U.S. Pat. No. 3,219,505), they prove to be unstable and lumpy once the peroxide is added to the system after storage. The similarly curable resins usable in the invention are those cured by a free-radical-initiated cross-linking mechanism such as vinyl esters and urethane acrylates. The compositions according to this invention can be used as fouling-resistant coatings on structures for use in marine environments e.g. boats, buoys, platforms, pontoons, etc. Abrasion of the surface to expose copper particles is not necessary when high levels of copper are used although it is preferable to do so when lower levels of copper powder or copper alloy (below around 30% by weight) are employed.
DETAILED EXPLANATION OF THE INVENTION
The resins are most commonly unsaturated polyester resins which are manufactured by the combination of an .alpha., .beta.-unsaturated dicarboxylic acid or anhydride, with or without the addition of a saturated dicarboxylic acid or anhydride and one or more glycols. The resultant condensate is dissolved in an unsaturated vinyl compound so that the liquid resin is 100% reactive and can be converted to a rigid crosslinked structure at room temperature by the addition of an organic peroxide in the presence of a promoter.
Typical examples of the various groups of compounds that can be used are: acid. terephthalic acid, tetrahydrophthalic anhydride, tetrahalophthalic anhydrides, chlorendic acid/anhydride, adipic acid, sebacic acid. diethylene glycol, dipropylene glycol, neopentyl glycol, dibromoneopentyl glycol, Dianol 33.RTM., Dianol 22.RTM.. bromostyrene, methyl methacrylate, ethylene glycol dimethacrylate. peroxide+cobalt soaps, acetylacetone peroxide+cobalt soaps, benzoyl peroxide+NN dialkyl arylamines.
Other resins that can be used are the so-called vinyl esters and urethane acrylates. Both of these have low acid values and a
REFERENCES:
patent: 3033809 (1962-05-01), Saroyan et al.
patent: 3219505 (1965-11-01), Hilding
patent: 3274137 (1966-09-01), Saroyan et al.
patent: 4081423 (1978-03-01), Hardenfelt
patent: 4197233 (1980-04-01), Marshall
patent: 4270953 (1981-06-01), Nakagawa et al.
patent: 4314850 (1982-02-01), Watanabe et al.
"Synthetic Addition Products," Polymers & Resins, B. Golding (Van Nostrand 1959), p. 403.
Encyclopedia of Polymer Science and Technology, vol. 12, (John Wiley & Sons, Inc., 1970), "Resin and Resin Derivatives", pp. 141-142.
Jacobs Lewis T.
Scott Bader Company Limited
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