US2965516A - Method for the preservation of wooden structures - Google Patents

Description

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15?.31 as i is alt-restate ,5 p f a heated Dec. 20, 1960 a pole with creosote and pentachlorophenol does not aid in the protection of the pole from fire since the cracks, 2 965 516 crevices and pole surface essentially remain exposed and METHOD FOR THE PRESERVATION OF WOODEN STRUCTURES Clarence E. Wilkinson, Port Neches, Tex., assignor to Texaco Inc., a corporation of Delaware No Drawing.

This in ention is concerned with a novel method employing a novel composition for protecting and preserving wooden structures such as marine pier piles and utility poles from the action of bacteria and fungi and from the effects of fire, moisture and weathering.

The novel composition of this invention has a combination of properties which makes it an economical and effective wooden structure preservative, viz.

(1) Low cost.

(2) Ready penetration of wood fiber on the surface, for example, where original creosote has been leached out.

(3) Excellent adhesives to wood surfaces.

' (4) Arresting wood decay, if started, and prevention of same if wood is fresh.

(5) Fire resistance, and

(6) A composition consistency so balanced that it can be rapidly forced into checks, pockets and cracks of wooden structures by ordinary spray gun techniques and then stay put without substantial sagging to provide a usefully heavy coat.

The novel method of this invention provides a simple, efiectiye and low cost means for substantially extending the life of wooden structures, particularly utility poles. More specifically, it has been found through the use of rny-novel method the maintenance and replacement of wooden structures can be reduced to a minimum without jeopardizing the operation of such structures. The method permits wooden surfaces areas whether large or small to be rapidly treated (e.g. by painting or spraying) using a small labor crew and provides an adherent protective coating which substantially prevents atmospheric weathering, decay and damage by fire.

This application is a continuation-impart of co-pending application, SerialNo. 430,401, filed May 17, 1954, now abandoned.

Wooden polesare commonly treated with creosote for the purpose of preserving the wood and in addition to the creosote, the'polcs are often painted with some fungitoxic material such as pen-tachlorophenol. Such protection means for the poles is generally satisfactory in protecting the wood from the effects of weathering except at about the earth surface level and below. At this point the decay of the wood has presented a serious problem. It appears that the ground water and/or earth surface water leaches the creosote and the pentachlorophenol from the wood; the bacteria and fungi in the soil and/or I water then attack the wood. Such decay has been found in many instances to more than halve the life expectancy of wooden poles.

In addition to the problem of decay, wooden poles are prone to damage by fire. This is accentuated by th; numerous cracks and crevices generally extending from the pole surface deep into the interior. These cracks and crevices when located in the area of the pole above the earth surface level .act as chimneys for fire and form excellent beds for the lodging of sparks from neighboring fires, e.g. grass fires. The end result of the lodging of these sparks is often a damaging pole fire. Coating furthermore, creosote, being a good combustible material, aids rather than hinders the propagation of fire.

In accordance with the invention, it has been discovered that by the application of my novel asphalt base composition containing a particular fungitoxic agent which is readily dispcrsible and capable of retention in the asphalt base under weathering and in the presence of moisture, the attack on the wood by bacteria and fungi can be effectively prevented. In addition, my novel composition upon application to the poles and with curing forms an efiective fire resistant coating. The ignition of the pole by sparks or flames from neighboring fires is discouraged for all the cracks and crevices are plugged and the pole surface is insulated by an adherent fire resistant asphaltic coating which forms an essentially smooth continuous surface.

The fungitoxic agent employed in my novel composition is copper-S-quinolinolate. It has been discovered that this compound is readily dispersible in the asphaltic composition and has a dispersion coetficient as between asphalt and water that is favorable to its retention in the former. In addition, copper-S-quinolinolate has been found to be stable at the relatively high temperatures needed to compound the asphaltic composition most economically.

The novel composition includes a suitable asphalt base cut back with a relatively light hydrocarbon distillate such as naphtha or kerosene. The composition also contains a quantity of asbestos filler. It has been found asbestos is an excellent material for arting the desired body and strength as well as fire resistant properties to the composition.

When applying the composition to utility poles in service, the soil is removed from about the pole for a depth of say l-2 feet or more. The pole is cleaned of any loose or decayed wood. If desired, a fungitoxic material such as pentachlorophenol or tetrachlorophenol solution may be first applied to the pole. The asphalt cutback composition of the invention containing copper-S-quinolinolate and asbestos is then applied with a brush or preferably sprayed on the pole with a spray gun so as to cover it for a distance of from about one foot or more below to well above the earth surface level. A good thick coating is applied such as /s-Mi inch in thickness. The treated section of the pole, may, if desired, be covered with an asphalt saturated felt. This gives additional pro tection although adequate protection has been obtained without this extra precaution. In applying the composition to poles prior to being installed, the pole is coated in the above manner over that section of the pole for which protection is desired.

The asphalt component of the protective composition consists of a good coating asphalt such as an asphalt prepared from parafiinic-asphaltic or asphaltic-cyclic crude petroleum residuum by steam or a vacuum distillation and/or air blowing. A suitable asphalt will have a softening point of about -180 ball and ring, a penetration at 77 F. of about 30-60 and a solubility in carbon tetrachloride of at least about 99.5 weight percent (wt. percent). The asphalt is mixed with a light distillate such as naphtha and kerosene. The proportions of the asphalt cutback in the totalmixture will be about 65-85 wt. percent. The amount of asphalt and volatilizable diluent comprising the cut-back will vary depending upon the consistency of the cutback desired but ordinarily the proportions will approximate 50-70 volume percent (vol. percent) of asphalt and 50-30 vol. percent ofdistillate. The volume percent is based on the total volume of the cutback.

I f i The cutback is mixed with asbestos fibers in proportions to yield a good plastic mixture capable of being applied to the wood. The asbestos content will ordinarily be within a range of 15-30 wt. percent of the total mixture. In using asbestos as the tiller, it is considered best to use fine asbestos in the mixture, e.g. substantially passing a 12 mesh U.S. standard screen, although it may be advantageous to use a small proportion of coarse asbestos, eg. substantially all retained on a 12 mesh U.S.-standard screen. These grades of asbestos are well known in the market, thus, for example, .lohns-Manville Corp. markets a fine asbestos as grade 7M and a coarse asbestos as grade 7D. Asbestos Corp. markets a fine asbestos as grade 7R.

The fungitoxic agent, copper-8-quinolinolate, is preferably added to the cutback prior to incorporating the asbestos. The copper-8-quinolinolate is available as a fine powder and it is advantageous to disperse it in a small amount of hydrocarbon such as kerosene and then add the dispersion to the cutback. Very small proportions of this fungitoxic agent are required. Surprisingly, it has been discovered that copper-S-quinolinolate is even more toxic at low concentrations than at higher concentrations in my composition. For example, in some cases 1 wt. percent concentration was found to be more effective than a wt. percent concentration. More particularly, concentrations of between about .05 to 5 wt. percent have been found effective with concentra-' tions between about 0.09 and 1 wt. percent being preferable. The wt. percent of copper-8-quinolinolate is based on the total mixture.

In an example of the invention, a composition was prepared consisting of 75 wt. percent cutback, 22.5 wt. percent fine asbestos and 2.5 wt. percent coarse asbestos. The cutback consists of 56.7 vol. percent asphalt, 43.3 vol. percent kerosene and had a viscosity of 164 at 122 F. Saybolt Furol. Copper-S-quinolinolatc was added in an amount of 0.2 wt. percent of the cutback. After removal of the soil for a distance about each of several utility poles in service and removing any loose or decayed wood therefrom, the asphalt composition was sprayed on a section of each pole to a thickness of about Vs-l inch beginning at a pole about 2% feet below ground level and extending about 1% feet above. The coating was allowed to set, after which the dirt around the hole was replaced. After a considerable period of time, the coating was stripped OE and no evidence of bacterial, fungal or moisture attack of the coated area of the poles was found. There was definite evidence of such attack on an uncoated pole used as a control. In some cases where it was necessary to back-fill around a pole immediately after the coating was applied, an asphalt saturated felt was wrapped around the coated pole. The coating, both with and without the asphalt felt, has proved highly satisfactory in protecting the poles.

In another example of the invention which emphasizes the excellent fire resistance of my novel composition as well as the novel method of protecting wooden poles from damage by neighboring fires, a composition was prepared consisting of 77 wt. percent cutback, 22.9 wt. percent fine asbestos and 0.1 wt. percent copper-8- quinolinolate. The cutback consisted of 62.0 vol. percent asphalt, 38 vol. percent kerosene and had a viscosity of 110 at 122 F. Saybolt Furol. The asphaltic composition was applied on the section of a utility pole to a thickness of V8% inch beginning at a point at the ground level and extending approximately 7 feet thereabove. It was observed the cracks and crevices in the pole were readily filled during the application operation. The coating was allowed to cure for 8 weeks. At the end of that period of time hay was stacked around the coated pole up to a height of 7 feet Strings were tied around the stack of hay to hold it in place. The hay .was then ignited at a point about 2 feet from the top of the stack on the windward side. Wind velocity at that time was about 10-15 miles/hr. The flames spread rapidly around the pole burning the string which permitted the burning hay to slide down the stack to the ground. Then the coated pole was engulfed in a very hot fire which, under the force of the wind, channeled up the pole a distance of 10-12 feet on the leewardside. Flame duration was 6-10 minutes. In a subsequent examination of the section of the pole underneath the asphaltic coating no evidence of charring was found and the coating itself remained substantially whole. The uncoated section of the pole exposed to the flames was severely charred.

The fire protection feature of the invention, of course, does not depend upon the presence of a copper-8-quinolinolate and therefore if fire protection is primarily desired and decay is not a problem, the quinolinolate compound may be omitted from the composition with a corresponding increase in the minimum quantity of asphalt cutback component from about wt. percent to about wt. percent.

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof and therefore only such limitations should be imposed as are indicated in the appended claims.

claim:

1. A method of protecting from moisture, bacteria, fungi and fire a wooden structure containing cracks and crevices therein comprising filling said cracks and crevices and coating the exterior surface of said structure with a compo s itihn consisting essentially of about .05-5 wt. percent oopper-8-qu ip c lip ol ate, about 15-30 wt. percent asbestos, and about 65-85 wt. percent asphalt cutback,

said cutback consisting essentially of 50-70 vol. percent asphalt and 30-50 vol. percent volatilizable diluent.

2. A composition in accordance with claim 1 wherein said copper-S-quinolinolate is present in an amount of about 0.09 to 1 wt. percent.

References Cited in the file of this patent UNITED STATES PATENTS 1,883,683 Gardner ct al. Oct. 18, 1932 2,054,285 Foster Sept. 15, 1936 2,396,910 Zaisser Mar. 19, 1946 2,552,947 Pasold et al. May 15, 1951 2,569,399 Burns et al Sept. 25, 1951 2,580,025 Holmes Dec. 25, 1951 2,608,556 Kalbert Aug. 26, 1952 2,738,286 Greider et a1 Mar. 13, 1956 OTHER REFERENCES Eisenschiml et al.: Ofiicial Digest (December 1948), pp. 953-962.

UNITED STATES PATENT @FHCE CER'llICATlN I ECWN Patent No'-., 2 965516 December 2O 1960 Clarence" E, Wilkinson It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1 line 42 for "surfaces" read surface column 3 line 6 after "substantially insert we all column 4 line 4'1 for composition" read method Signed and sealed this 23rd day of May 1961;,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents

Claims (1)

1. A METHOD OF PROTECTING FROM MOISTURE, BACTERIA, FUNGI AND FIRE A WOODEN STRUCTURE CONTAINING CRACKS AND CREVICES THEREIN COMPRISING FILLING SAID CRACKS AND CREVICES AND COATING THE EXTERIOR SURFACE OF SAID STRUCTURE WITH A COMPOSITION CONSISTING ESSENTIALLY OF ABOUT .05-5 WT. PERCENT COPPER-8-QUINOLINOLATE, ABOUT 15-30 WT. PERCENT ASBESTOS, AND ABOUT 65-85 WT. PERCENT ASPHALT CUTBACK, SAID CUTBACK CONSISTING ESSENTIALLY OF 50-70 VOL. PERCENT ASPHALT AND 30-50 VOL. PERCENT VOLATILIZABLE DILUENT.