合成樹脂を應用する木船虫害防除方策に就て(第1報)

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During the last five years the authors have supervised 11 series of exposure tests, ranging from 6 to 25 months, of Japanese cedar samples tested in various ways to prevent attack by marine borers. Some of the new methods were applied to more than 20 ships sailing to the southern seas, but unfortunately most of them were lost or destroyed before adequate Tests could be completed. Protective methods generally in use for saving wooden ships from borers are either chemical or mechanical. The chemical method kills the borers by painting or injecting preservatives or toxicants into the wood. The mechan cal method prevents borers from reaching the timber by sheathing it with sheet metal or specially treated fabric. Observation of exposure tests on materials treated by these two methods have given the following results : 1) Painting the exposed surface with a chemical substance harmful or disagreeable to marine borers such as copper paint, is commonly practiced as the most effective and practical method in use at present. This method is not permanent because the protective substance either gradually leaches out, or the coating itself is destroyed by abrasion in a very short time. Subsequently frequent docking and renewal are necessary. 2) Sheathing the bottom with an outer board with an intervening layer of tar paper has been considered resistant, but their experiments show it quite ineffective against both shipworms and boring crustaceans over a two year period. 3) Impregnating the wood with pre ervatives and toxicants is cons dered better than coating, but the large amounts of impregnants necessary, and the increase of weight to the ship are undesirable. 4) So far as the weight i concerned, sheathing the bottom of a ship with thin wood impregnated with creosote or copper hydroxide is better than injecting the hull itself. But the impregnated boards lengthen the life of the ship only until the injected tox cants leach out of the thin wood, which is usually within a year. No chemical method depending on tox city lasts over one or two years. Next they tested various methods of applying soluble urine resin compounds, which may be so treated as to make a hard, unsoluble outside layer, giving mechanical as well as chemical protection. Results were obtained as follows : 1) Test pieces pa nted with urine resine compounds were not attacked by the borers after one and one half years. and after two years the test pieces were attacked slightly only at one corner where the coating abraded. The method is more effective than painting with copper. 2) The two year tests of an intervening layer of urine resin compounds give complete protection against the borers. Veneer plates with two or three protective layers of urine resin compounds may be applicable for the outer protective boards of ship. 3) Samples sheathed with thin boards injected with urine resin compounds lasted two years against borers. 4) Another important result of this method is the waterproof quality imparted to the woodtself. The weight of samples after two years test in the sea showed only 10-20% increase remakably lower than that of the other methods which allow sometimes up to 120% increase in weight.
社団法人日本船舶海洋工学会の論文

合成樹脂を應用する木船虫害防除方策に就て(第1報)

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