US 2708170 A
Description (OCR text may contain errors)
United States Patent ROOFING CEMENT Ray Russell Hampton, Savannah, Ga., assignor to Southport Paint Company, Inc., Savannah, Ga., a corporation of Delaware No Drawing. Application December 6, 1949,
Serial No. 131,488
6 Claims. (Cl. 106280) coating, hereinafter called the cement, which is applied Over the usual felt base that is bonded to the roof deck.
The following description, except for my improved cement composition, is applicable to roofs of well known construction.
A base sheet, comprising one or more layers, of
asphaltor tar-saturated felt, is nailed or bonded to the roof deck and coated with cement of the composition hereinafter described. A layer of flexible aluminum foil is rolled into the coating. The aluminum foil is then coated with the specified cement. Into this upper coating is then poured, spread or rolled granite chips.
Of the above elements, the base sheet may be of standard type. It may be of different weights, both lb. and lb. weight being customarily used.
For the granite chips may be substituted marble chips. Both are standard surface coatings. Granite chips are of A to A size and specifications usually require a minimum of 125 lbs. per 100 sq. ft. of roof surface. If chips of pumice, slag or coral rock are used, the minimum coverage should be 125 lbs. per 100 sq. ft. of roof surface. Where marble chips are specified, they are usually minimum and A maximum and specifications usually require 225 pounds per 100 sq. ft. of roof surface.
It will be understood that the above elements, except for the special cement, are conventional. So far as permitted by specifications, any felt body, impregnated with asphalt, or with tar or any other equivalent, may be utilized as the base sheet. Any light weight thin metal sheet, such as copper or zinc foil, may be considered an equivalent for the aluminum foil, but the latter can be relied upon to give the most entirely satisfactory results, and in aluminum life roof specifications, aluminum foil and white or pink marble chips are usually required. Marble chips and any other mineral chips, such as slag, coral rock or pumice, that may be permitted by specifications are equivalents of the granite chips.
The novel element of the above construction is the composition of the roofing seal or cement. A preferred composition comprises cotton seed oil gum 30.3%, petroleum distillate 36.5% and mineral filler 33.2%.
For the cotton seed oil gum may be substituted gums from soya bean, linseed, peanut and any other gumbearing vegetable oils or mixtures thereof, but a ee- 2,708,170 Patented May 10, 1955 ice ment comprising cotton seed oil gum, alone or in greatly predominating proportion, gives the best results. While, as above stated, a mixture of two or more of such gums is permissible, it is safer to utilize a single gum, since some combinations of gum-bearing vegetable oils have a tendency, under some temperatures and physical conditions, to separate, volatilize or 'saponify.
Any suitable mineral filler may be employed, but asbestos fibre, magnesium silicate and, carbon (black) are the only metal fillers that give entirely satisfactory results so far as concerns bonding or sealing, brush or spray consistency and freedom from gas bubbles and color effect.
The gums may be thinned with anyv volatile thinner, such as mineral or vegetable oils, or a mixture of two or more such oils. Preferred thinners are mineral spirits, kerosene, gasoline, spirit turpentine, Wood turpentine and pine oil. If a petroleum or other hydrocarbon distillate is employed, it is preferred to use a petroleum distillate having an end point approximating 200 C.
Adherence to the precise specified proportions of the components of the cement is of course not necessary. The proportions may vary from those given within plus or minus ten per cent and even beyond that range with,
however, some sacrifice of certain of the advantages hereinafter enumerated. It is, in fact, undesirable for the variation to exceed plus or minus five per cent. Thus the ranges of the constituents should not much exceed the following: cotton seed oil gum, from about 28 to 33%; mineral filler, from about 28 to 35%; and hydrocarbon distillate, from about 32 to 42%.
The advantages of the above described roofing may be enumerated as follows:
Lightness in weight.
A fewer number of layers of felt.
Greater binding strength.
Less tendency to creep.
Absence of mineral or animal tars or fats. Non-bleeding into white oil paints applied over it.
Cotton seed oil gum is usually known in the trade as cotton seed oil pitch. The product is a residue of distillation in the recovery of fatty acid contained in the whole. The melting point ranges from 24 to C., with a stretch test of from 4 to 30 inches. However, it is distinctly preferred to use this gum or pitch with a range of 37 to 50 C. melting point, with a stretch of from 8 to 20 inches under standard ASTM method.
If soft, or low melting point, vegetable gum is used alone, the mineral content must be increased to avoid creeping and some separation may result and fire resistance may be lowered.
If hard, or high melting point, vegetable gum is used alone, the mineral content may be lowered, thus lowering the non-volatile content, but adhesion, flexibility and binding quality are reduced.
It is distinctly preferred, therefore, to take hard gum, bring it to solution-mixing stage, and incorporate a solution of soft (low melting point) gum thinned with mineral spirits. The result is a solution to which can be added necessary minerals and solvent, the product retaining the natural stick qualifies, fire resistance and, above all, resistance to complete drying between layers of foil or felt.
While the above statement of advantages is applicable, in greater or less degree, to any of the cement compositions above described, a roofing in which the cement is of a composition that includes cotton seed oil gum has values that are more pronounced as to one or more, or possibly all, of the following characterter and resistant to acid, inexpensiveness, ease of ap plication, adaptation for use on both flat and steep roof surfaces, maximum quantity for a gum area, resistance to displacement after application, and resistance to weather including immunity to heat, cold or abrupt changes in temperature in that cotton seed oil gum expands or contracts with such changes. Cottonseed oil gum is slow-drying, the drying being from the outer face inward until a tough leather-like skin is formed. The percentage of solids in the gum itself is low and the gum is not dependent on oils for plasticity, so that there is less likelihood to crack, peel, chip or blister. Because of its low dye content, no bleeding occurs when it is painted with oil paints, which, on some'gums, would act as solvents. Because of the superior qualities of cotton seed oil gum as compared with other vegetable oil gums, I desire to claim it specifically.
What is claimed is:
1. A roofing cement for use, in one or more layers, in association with a felt base and one or more layers of metal foil, said cement consisting essentially of a mixture of vegetable oil gum, a volatile hydrocarbon distillate adapted to thin the vegetable oil gum, and a mineral filler, the proportions of said constituents not varying over about 5% from the following proportions: vegetableoil gum 30.3%, volatile thinner 36.5% and mineral filler 33.2%.
2. The roofing composition defined in claim 1 in which the vegetable oil gum is a cottonseed oil pitch having a melting point range between 24 to 65 C. and a stretch test of from 4 to 30 inches under standard ASTM method.
3. The roofing composition defined in claim 1 in which the vegetable oil gum is a cottonseed oil pitch having a melting point range between 37 and 50 C., and a stretch test of from 8 to inches under standard ASTM method.
4. The roofing composition defined in claim 1 in which the mineral filler is selected from the group 4 consisting of asbestos fibre, magnesium silicate and carbon (black). 7 a
5. A roofing cement for use, in one or more layers, in association with a felt base and one or more layers of metal foil, said cement consisting essentially of a mixture of vegetable oil gum, a volatile hydrocarbon distillate adapted to thin the vegetable oil gum, and a mineral filler, in which the ingredients are in the following proportions: vegetable oil gum 28 to 33%; hydrocarbon distillate 32 to 40%; and mineral filler 28 to 35%.
6. The herein described process of producing a roofing cement one or more layers of which, together with one or more layers of metal foil, are adapted particularly for application to a felt base to thereby provide a roofing material, which comprises bringinga relatively hard and high melting point vegetable oil gum to a solution-mixing stage and incorporating therewith a solution of a relatively softandlow melting point vegetable oil gum thinned with a volatile thinner, and
mixing the same with a mineral filler in such proportions that the cement will contain from 20 to of the thus produced vegetable oil gum, from 27 to 46% of volatile thinner and 23 to 43% of mineral filler.
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