US2075751A - Method of reclaiming waste material for reuse and products made thereby - Google Patents

Description

Patented Mar. 30,1937

UNITED STATES PATENT OFFICE METHOD OF RECLAIMING WASTE MATE- RIAL FOR REUSE AND PRODUCTS MADE THEREBY No Drawing. Application April 3, 1931, Serial No. 527,612

2 Claims.

This invention relates to improvements in the manufacture of composition building material and is particularly concerned with improvements in the manufacture of asphaltic composition roofing material or the like.

In the manufacture of asphaltic roofing material and particularly in that branch of the industry wherein felted fibrous foundation material is saturated and coated with asphalt or the like, and surfaced with comminuted mineral material for the production of various types of asphalt shingles and shingle strips, large quantities of waste material are accumulated under normal commercial production. This waste is in the form of trimmings, tabs, or cut-out pieces resulting from the severance of the parent sheet into shingles and shingle strips of various shapes and styles; and also in the form of a certain unavoidable quantity of imperfect material or so-called seconds. This Waste material normally amounts to approximately 3% of the total production and considering the fact that hundreds of thousands of tons of roofing material of this character are produced annually, this seemingly small percentage of waste actually represents an enormous loss to the manufacturer in the cost of the felt, asphalt and mineral surfacing of which the waste is constituted, and in addition imposes upon the manufacturer a very troublesome problem in disposing of the waste. Numerous suggestions have been made for the conversion of this waste material into various types of so-called specialty products, but the consumption of the waste for these purposes, has thus far not been sufficient to keep pace with the waste unavoidably produced, and at any rate this-avenue of attack upon the problem has failed to provide for the consumption of the actual waste produced, and only to a very limited extent has it provided any profitable means for converting the waste into other products.

The principal object of the invention is to provide a method for the useful recovery of the waste or scrap material normally produced in the asphalt roofing industry.

According to the present invention this problem ofdisposing of and usefully reclaiming the waste material is solved with a view towards concurrently improving the quality of roofing and siding material as produced in the asphalt roofing industry.

In the manufacture of asphaltic roofing or the like it is customary to saturate or impregnate a sheet of bibulous felt with asphalt or the like in order to make the foundation water resistant and then to provide the weather face of the sheet with a'coating of molten or blown asphalt which serves as a weather protective medium, comminuted surfacing material such.

as crushed slate or the like being usually applied 5 to the coating layer and caused to become partially embedded therein, to mask the coating material from the effect of the solar rays and to provide a decorative finish for the product. The

coating material usually employed for this purpose is an asphalt air-blown or oxidized from a petroleum residuum to a melting point of 200 to 230 F. and a penetration varying from to 25 at 77 F. The weathering properties, pliability at low temperatures and certain other qualities 15 of the coating material have been improved in accordance with practice heretofore-known in the art, by the incorporation therein of suitable quantities of finely divided inert mineral filler.

In accordance with the present invention the waste or scrap material accumulating as aforesaid in plants where prepared asphalt roofing is manufactured, may be advantageously reclaimed for reuse as a filling material for the asphalt going into the manufacture of the asphaltic roofing material as a coating therefor.

Where inert mineral fillers are employed as a filling material for coating asphalt, the beneficial effects thereof are realized when the filler material amounts to from say 10 to of the asphalt 30 by weight. Under normal practice mineral surfaced asphalt roofing may be said to consist of approximately 12 to 15% by weight of fibrous material in the form of the felted foundation;

50 to 60% by weight of the asphalt constituting the saturant and coating therefor; and 25 to 35% by weight of mineral material in the form of a surfacing for the coating. .Of the asphalt contained in the waste, approximately 50% thereof by weight, represents that which is present as coating material upon the felt foundation. Illustrating the foregoingfigures by a specific example, it may be said that for asphalt coated and mineral surfaced roofing material in which the foundation felt comprises say 17 pounds per 108 square feet (a factory square) the asphalt saturation amounts to approximately 32 pounds, the coating asphalt approximately 28 pounds and the mineral surfacing material approximately 28 pounds.

According to the invention, the coating material may be filled with inert filler in an advanta geous way by using as the source of the filler material, the waste or scrap material that accumulates during the course of manufacture cf 5 the product made from material of this type. The principal object of the invention is thus accomplished with a concomitant improvement in the quality of the finished goods, the normal production of waste material being thus utilized as a filler for fresh asphalt to be used as coating material, to the extent of about ten percent by weight of the asphalt. Since approximately one-half the weight of this waste material is represented by the asphalt contained therein, the net introduction of inert filler in the form of the mineral and fibre components of the waste approximates five percent by weight of the fresh asphalt.

The invention accordingly provides means whereby the manufacturer may profitably and advantageously reclaim the waste and second class material, for use in the process of manufacture of first class material, as fast as the waste is produced in the process.

It will be understood of course that where the amount of filler desired in the coating material is greater than the net amount provided by or derived from the waste incorporated therein, as hereinafter. to be described, the waste material may be supplemented with other inert substances for incorporation into the asphalt coating material. In fact, in the practical operation of the process forming the subject matter of this invention, substantial quantities of other inert mineral fillers are thus combined with the waste material as will more fully hereinafter appear.

In order that the invention in its several aspects may be clearly understood by those skilled in the art, a detailed description thereof will be outlined herein, in the best modes which are now contemplated for applying the principles thereof in practice.

Briefly stated, the invention in one of its embodiments may be carried out by comminuting or pulverizing the waste material whereby it is transformedinto the form of a more or less granular powder which is then mixed with substantial quantities of molten blown asphalt in order to form a coating material carrying the mineral and/or fibrous components of the waste in suspension therein, the asphalt components of the waste readily fiuxing with the molten asphalt, and the whole forming a heat-liquefiable composition, which at temperatures of say 350 to 475 F., depending upon the melting point of the asphalt, and the quantity of filler contained therein can be pumped and fed to the point of application, and otherwise handled in substantially the same way as is possible with asphalt normally used as coating material. By the term liquid at temperatures between 350 and 475 F. as used in the claims, we mean such fluidity within said temperature range as will enable the composition to be pumped and fed through the pipes usually employed for handling molten asphalt of 200 to 240 F. melting point in a roofing plant.

In carrying out the invention, the waste or scrap material in the form of cut-out tabs, trimmings and shingles or shingle strips denoted in the reefing industry as seconds, etc.', may be introduced into a suitable machine which will reduce the waste to the form of a granular powder of an appropriate state of fineness for ready and convenient introduction into molten asphalt. The fineness of the material after this treatment should preferably be such that the bulk thereof will pass a 20 mesh screen, oversized material being separated and recycled if desired. Preferably a hammermill is employed for reducing the waste material to the granular, subdivided or 13121-- verized condition. These hammermills, as well known, consist of a seriesv of hammer heads mounted upon arms extending radially from a central rotatable shaft and operating to strike the material fed to the mill rapidly repeated shattering .blows while the material is suspended in the mill, until it has been reduced to a size sufficient to pass a screen mounted near the bottom of the machine. By selecting a screen of appropriate sizethe mill may be employed by its continued action to reduce waste material of the character herein referredto,'to a size as above specified.

Under the action of the hammermill the fibrous felt component of the waste becomes defibrated, so to speak, and the asphalt and granular components thereof become pulverized or comminuted. the whole forming a granular powder as above described.

With a machine of this character, wherein th attainment of the desired degree of pulverization or sub-division of the waste material is controlled or determined by the use of a screen of suitable mesh, it is desirable to introduce into the machine, along with the waste material to be treated therein, substantial quantities of finelydivided mineral material such'as slate flour, talc, or mica in order to preclude the clogging of the meshes of the screen by the asphaltic constituents of the waste which may become sticky or gummy under the action of the mill.

Powdered non-adhesive material such as talc v or mica, which itself is capable of functioning as a filler for asphalt coating material will accomplish this purpose when employed in quantities say from one-half to equal parts by weight of the scrap or waste material fed to the mill. For this purpose also, there may be used waste mixed granules; such as crushed slates of mixed colors which also accumulate unavoidably in the commercial manufacture of mineral surfaced roofing, the waste mixed granules being pulverized in the hammermill and serving to prevent clogging of the screens. The finely divided material thus employed in conjunction with the scrap for preventing the clogging of the screen in the mill becomes intimately' admixed with the pulverized scrap delivered from the mill .and is altogether desirable .as additional or supplementary filler material in excess of the net amount derived from the scrap.

As an alternative method, a dilute solution of sodium silicate or other surface tension reducing material such as soap, may be fed into the hammermill with the scrap. With sodium silicate about 6 percent of diluted material will effectively prevent sticking of the material and enable the desired reduction to take place. The reduced material so obtained must of course be free from moisture before being introduced into the hot asphalt and this can be readily done by employing warm air or other suitable means as a drying medium in connection with the removal of the reduced material from the hammermill.

The material as delivered from the hammermill may then be incorporated into molten blown asphalt to be used as a coating material in the production of further quantities of the asphaltic composition roofing material. For this purpose any suitable and convenient form of mixing equipment may be employed for bringing about a uniform dissemination of the pulverized or comminuted roofing scrap through the asphalt. The asphalt employed may be that which is customarily employed for coating prepared roofing and may be of a melting point of about 210 to 230 F. and a penetration of say 15 to 25, but it is an advantage of the present invention that asphalt of lower melting point, say 160 to 210 F. may be employed, the resistance to flow thereof at temperatures above the melting point of the asphalt being increased by virtue of the presence of the constituents of the waste material incorporated therein. The amount of asphalt that may thus be mixed with the comminuted or pulverized waste material may vary from say two to ten times by weight of the waste. It will be seen therefore that where the waste material is subjected to the 16 action of the hammermill in the presence of equal parts by weight of a material such as tale in order to keep the screen in the mill clean during the operation, and the resultant material mixed with molten asphalt in the proportion of ten times 20 the weight of the scrap, the composition thus produced will consist. substantially of 85 to 90% by weight of asphalt, 10 to 12% by weight of the mineral material and 1 to 2% by weight of fibre. This composition will be fiuid at temperatures of 300 to 475 F. and hence may be conveniently delivered through pumps and feed pipes to the roofing machine where it may be applied as a coating layer to a base or foundation sheet of asphalt impregnated roofing felt or the like. By main- 0 taining the composition for a sufiicient period of time during the incorporation of the comminuted or pulverized waste therein, or subsequently thereto, at or near the higher temperature figures within the range above specified, the fibrous components of the waste may be caused to become carbonized, the resultant carbonaceous matter then acting as additional filler.

Where necessary or desirable, the composition may be passed through a closely confined annular 40 rotating working surface and a static surface, whereby to break up or distribute any small lumps that may be present andto homogenize the composition. An apparatus for this purpose may comprise an ordinary refining engine or Jordan such as employed in refining paper stock, the

machine being steam jacketed so that proper temperature may be maintained to permit the composition to fiow therethrough in 'heat liquefied state. Any other suitable steam jacketed ma- .0 chine capable of homogenizing the composition as aforesaid, however, may be employed in lieu of a Jordan.

The consistency of the filled coating is such that it readily adheres to the sheet of impregnated felt and it is susceptible to imbedment therein of granular material such as crushed slate as a surfacing material for the coating in the customary way.

It will be understood of course that where addisay to of asphalt, 30 to 40% of mineral matter and 1 to, 5% of fibre.

By the terms scrap asphalt treated felt or waste as employed in the claims hereunto appended, we intend to include all manner of waste material including trimmings, cut-o'ut pieces or sections, imperfect finished or unfinished lengths or sections of material and seconds (so-called) such as produced and accumulated in the commercial manufacture of asphalt prepared roofing and like products.

We claim as our invention:

1.- Prepared roofing material comprising a felt fibrous base impregnated with waterproofing material and coated on a surface thereof with a layer of bitumen having a melting point of 200 to 240 F., said coating carrying a filler comprising pulverized scrap asphalt roofing in an amount approximating 1/10 the weight of the bitumen, said filled coating being liquid at temperatures between 350 and 475 F.

2. Roofing material comprising a fibrous base saturated with asphalt and carrying a layer of pliable coating, said coating comprising asphalt of to 230 F. melting point and containing the disintegrated components of asphalt saturated mlneral surfaced roofing scrap, said coating being liquid at temperatures between 350 and 475 F.

RALPH W. B. READE.

HAROLD L. LEVIN.