US2956908A - Oil resistant coated gasket material - Google Patents

Description

Oct. 18, 1960 H, L. BRowNBAcK 2,956,908

OIL RESISTANT COATED GASKET MATERIAL Filed April 25, 1956 OIL RESISTANT COATED GASKET MATERIAL Henry Lowe Brownback, Deer Isle, Maine Filed Apr. 25, 1956, Ser. No. 580,661

1 Claim. (Cl. 117-167) This invention relates to oil resistant compositions suitable for making gaskets, or coating, or touching surfaces to be sealed, or for spraying to serve as adherent coverings, and is herein illustrated in considerable detail as embodied in gasketing material and grafting material, and also as a material suitable to be sprayed either on metal surfaces or to be sprayed on exposed cambium cells of growing trees to protect them, so that the exposed part may regrow the needed bark.

The present application is a continuation-impart of my prior application Ser. No. 260,580, filed December 7, 1951, and now abandoned.

In a prior patent has been disclosed a blown oil, such as castor oil, which is stabilized by the addition of a stabilizing material and then used as a gasketing material which has proved extremely satisfactory because the castor oil is oil resistant and withstands fairly high temperatures.

It has been found to be almost the only satisfactory gasketing material for sealing outlet joints in bottled gas containers commercially where the bottled gas is stored indoors under high pressure for domestic or similar use.

`It has now been discovered that blown castor oil which is the residue left after blowing heated castor oil at such a heat and such speed that large proportions of acrolein comes off possesses additional advantages and that these advantages are enhanced when mixed with a small but effective proportion of a silicone material.

According to this invention the castor oil is blown preferably while giving oif acrolein until it attains a viscosity of 2000 poises or more or becomes a tacky gel, which, when properly stabilized, remains elastic over a long period, is insoluble in a large variety of organic solvents, especially petroleum products, is practically unaffected by water and steam, and remains unchanged over a period of years.

A detailed description of producing a satisfactory blown castor oil is describedl below.

To obtain all the advantages of the present invention, the blown castor oil, which may be this type, is combined with a silicone which may be a dimethyl silicone of at least 30,000 centistokes viscosity, or a polymethyl silicone of a viscosity of from 1,000,000 to 5,000,000 centistokes at 25 C. In even very small proportions the added silicone increases the lubricating properties of the castor oil used especially at extremes of temperature.

It is found that the amount of the added silicone may vary widely but need not be great, and that both the silicone and the blown castor oil are soluble in toluene and some other volatile solvents, especially aromatic solvents, so that they may be thin enough to form a sprayable material or may be liquid into which gaskets or other structures may be dipped, taking up the solution and drying out to carry a tough, exible covering or saturation, resistant to a very large number of ordinary dissolving and chemical agents. Other thinners are ite States Patent carbon tetrachloride, ethyl alcohol, and a propyl alcohol.

The castor oil blown as described, is on the market, as a by-product of the French perfumery industry in which it is obtained when the castor oil is blown to yield volatile substances used in perfumery, and the residue is useless for that end although valuable in the present invention.

The polymethyl silicone may be one of the empirical formulas, such as which is commercially available material in liquid form having the necessary resistance to most solvents, to heat, and to chemical agents.

The named polymethyl silicone has freezing point of 416 C. to -50 C., a boiling point of 200 C. anda ash point of 315 C.

The polymethyl silicone can be combined with the blown castor oil above described, by dissolving the polymethyl silicone in toluene and then dissolving the blown castor oil in the toluene so that the final material may contain toluene, 18% castor oil and 2% polymethyl silicone. This mixture or solution is capable of being sprayed in commercially available sprayers and is taken up by suitable gaskets as for dipping, painting, although they may be fully saturated when partly or largely porous instead of merely coated. The blown castor oil described can be mixed with some properly chosen polymethyl silicones by mechanical mixing, or the polymethyl silicone may be dissolved in the raw castor oil by mechanical mixing, and the mixture of polymethyl silicone and raw castor oil then blown while hot just below the boiling point of the polymethyl silicone until the desired 2000 poises viscosity is attained. At this point suitable inhibitors to arrest further oxidation of the castor oil may be added to the amount of say 1/2 of :1% to 11/2 Suitable inhibitors are phenyl-alpha-naphthyl-amine, hydro-qunone and iodine.

Where the mixture is not to be sprayed it is often desirable, especially for gasketing, to add by mixing in a suitable quantity of an extender or ne ller, such as a short fibred line asbestor, powdered cork, or even saw dust, or possibly wood flour. Flake graphite is especially useful yas Ea ller in gaskets likely to be heated so hot as to char the oil, since the graphite continues to function as -a lubricant even in threaded joints, enabling the threaded-on part to turn even if the gasket has charred. As little as 25% and as much as 50% of added filler has proved useful.

The inhibitor is preferably added to all of the compounds mentioned above which carry the blown castor oil and the ller will be added only to such compounds as are benefited by extending them with a filler such as rubbed on gaskets `or graft coverings.

For some purposes it is possible to substitute some semi-drying oils such as cottonseed oil, and corn oil, or drying oils such as linseed oil and tung oil or rape seed oil or mixtures of any of these for the castor oil, but these substitute glyceride oils are not as resistant to as many solvents and chemicals even when blown as is the castor oil, and the amount of'blowing required will vary with the constitution of the oil.

The sprayed on oil mixture of the present invention wil be found to replace or supplement many forms of gaskets in some types of construction, such as automobile engines, and is resistant to gasoline in a way that few other materials are resistant to it, so that it will make a metal joining of two surfaces gasoline-tight if 3 the material of the present invention is sprayed thereon before the surfaces are brought together.

It has also been found possible to apply the mixture carrying a suitable thinnerby a roller typeapplying device. Fo'r this purpose a less volatile thinner, s'uch as diethylene glycol, may be more satisfactory. Sueh a `procedure works because the material of the v f vriesentinvention remains tacky instead of becoming hard as the Vbrittle in the'mold as when'thefengineis left standing'for along vtimeexposed to the Jwinter weather. While many blownoils may b'e satisfactory for `so`rne purposes, the'be'st'seerr'is 'tobea blown castor oil product as described below. Such an oil' has a characteristic tackiness which is found a suitable test for other blown oils 'when 'anal'agous compositions are produced for other utilities.

In the accompanying drawing is"`shown a 'device found ysuitable for producing lthe most satisfactory blown'oil for incorporating into the present invention. 'In that "drawing `Fig. lis a ldiagrar'rrniatic sectional side view of the blowing apparatus.

Fig. 2 is an enlarged Vsectional view on the'li'ne 2"-#2 of Fig.' 1.

Fig. 3'is`a similar v iew on the line 3-3 of'Fig. 1

'The deviceshown includes 'notonly the containerand means for blowingtheoil, 'but'al's'oshowsa v'isconieter "embodied therein.

'Inthe formshown a' mixture of 120 liters of raw castor oil with 130 liters of castor oil blown to'a viscosity of 30 centipoises, as measured on a standard viscositynleas'uring machine, is placed in the container 10 having a height from bottom to inside of cover rim 11 about y900 millimeters and `a radius of about 750 millimeters, and air is blown in at a temperature of 205 C; on a volume of 90 cubic meters per h our at a pressure of 1.4 kilograms 'per square centimeter at the entrance to the kettle.

The oil lills' the kettle to aheight of'about '670millimeters and the air enters through'a vertical pipe'12 extending downto an 'annular distributor passage`13 clearing the bottom by about 100 millimeters.

`From this manifold or distributor 13 extend radially six equally spaced round distribution pipes 14 about '2 0 millimeters internal diameter and perforated around their bottom holes with closely set 2 'millimeter openings v'15 to the air is directed principally downward.

The pipes 14 terminate about 50 millimeters clefar of the inside of the wall of the container 10, thus allowing oil to circulate freely around them.

The oil is agitated during theadmission of air by a four-bladed variable pitch agitator 16 turning at about 1200 to 1500 r.p.m. carried at the bottom 'of a vertical power driven shaft 17 'so that the blades, about 340 millimeters from tip to tipv keep the oil circulating through the open center of the manifold 13, and clear the tie rods 18 which support the manifold 13 near the periphery.

vThe best results, predictably uniform, were'obtained'by the procedures described'below.

The oil after being placed in the container 10 'was blown by entering air through the pipes 14 and agitated by the agitator at about 1200 r.p.m. until the oil reaches a temperature of 205 C., usually about 45 minutes, -as shown on the thermometer 19 with its bulb immersed in the oil, the oil is tested by being drawn in through the submerged nozzle 20 of a viscometer 21.

This viscometer takes the form of a 20 millimeter long tube 22 xed in the toplof thecontainer 10 and carrying thenozzle 2 0 withacentral 'cylindrical opening 23 three millimetersin diameter, spreading to eight millimeters in twelve lmillimeters and openinginto the tube 22-"at the end of 20 millimeter s r 1 1pr e The tube 2`2'termiuate's at the top in a glass bulb 24 holding one liter'betwen itsindex lines, and the bulb 24 is connected by a passage 25 to a three way cock 26 turnable to open it to a suction line 27, or to a line 28 open into the top of the container 10.

When the blown o i l ha s. re ached the temperature of 205.` 'C..and'thesu'ction isturned on the tube 22, the oilmfillsvthe bulb T4 in about 55 to v5S seconds, the impell'er being st opped'but blowing air continued.

VThe bulb 24 `is then emptied back'into the container byturningthecock 26 and the blowing continued until ythe desired oxidized consistency is reached, usually `four to'four and one-half hours, and the consistency is measured't'o this end by measuring the time to refill the bulb 24, which should b'e'80 to 82 seconds.

It'shouldbenot'ed that the oil gives off acrid vapors zand other volatiles while being blown andthese are Vcar- .ried ofl` by a large vent 29, and may be absorbed by sulfurie.' acid, .preferably carried in broken earthenware through which the gases bubble.

After the 82'secon/d reading is reached the impeller is sto'ppe'd but is blown in until the temperature has dropped to 'C. to 110 C. Then antioxidant is added (rnelted, if need be), any solvent used is added also 'any other additives, s uch'as llers.

'Itis found' that Yworkers in this process s oon learn 'toernpirically test 'an oil by observing its tackiness and f n'ny blown oils they'thus test and approve are at least fairly satisfactory for the present invention to replace the lcastor oil thus blown.

Having thus described certain embodiments of the in- "vention, what is claimed is:

Gasket material having on its outer surface a coating of an adherent sealing composition prepared by combinjing'a blown castor oil forming a tacky gel and having "a "viscosity of at least '2,000`p oises with adin'iethyl silicone having va viscosity lofat least 30,000 centistokes iu "the proportion of approximately 9 to 1 by weight.

'References Cited in the le of this patent UNITED STATES PATENTS 2,054,801 .Bailey Sept. 22, 1936 2,129,281v Lincoln et al. Sept. 6, 1938 .2,317,487 Schuelke Apr. 27, 1943 2,327,450 Parker Aug. 24, 1943 2,442,196 Coggeshall May 25, 1948 V2,466,642 Larsen Apr. 5, 1949l `A2,467,178 Zimmer et al Apr. 12, 1949 2,491,843 wilck Dec. 20, 1949 2,523,065 vSage Sept. 19, 1950 .2,557,928 Atkinson June`26, 1951 2,635,060 Cheronis Apr. 14, 1953 oTHER `luaFEREtsIcns ;McvG'regor: Silicones and Their UsesfiMcGraw-Hill,

1954, pp. 176-177, 201, 207, 217 relies on.

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