US2276487A - Coating method - Google Patents

Description

March 17, 194 N. P. HARSHBERGER COATING METHOD Original Filed April 29, 1939 'INYENTOR, MmmZA mskzqzr 044 AT T o R N E Y Hm. I )IIIIIIIIIIIIIIII I III lllllll Patented Mar. 17, 1942 COATING'METHOD Norman P. Harshberger, Old Greenwich, Conn., assignor to Carbide and Carbon Chemicals Corporation, New York, N. Y., a corporation of New York Original application .April 29, 1939, Serial No. 270,730. Divided and this application May 27, 1941, Serial No. 395,372

14 Claims.

This invention relates to methods for coating particulate materials, for instance, roofing granules, and to methods for producing continuous coatings comprising particulate materials and a binder. The methods are particularly applicable to making cement coated roofing and siding, for instance, of the type disclosed in my prior Patent No. 1,913,667, granted June 13, 1933, wherein, for example, a felted fibrousbase is saturated and coated with a bitumen such as asphalt, then surfaced with a layer of granular particles, and subsequently surfaced on the granule sid with a cement composition.

The present invention is a continuation-inpart of my co-pending application Serial No. 26,770, filed June 15, 1935, now Patent No. 2,156,286 and is a division of my co-pending application Serial No. 270,730, filed April 29, 1939.

Prior particulate coating methods have generally required large batch mixing and tumbling operations. Batch mixing has also been the case where it has been desired to provide coatings with aggregate material to furnish coloring and filler properties. These methods require much apparatus, many operations, and much handling of the materials.

The present invention aims to provide simple, efiicient and readily controlled methods for the purposes described.

An object of the invention is to provide a method for coating individual pieces of particulate material with coating compositions; in particular, compositions of a sludgy or plastic consistency.

Another object is to provide a method for producing fully coated individual particles, for instance, coated roofing granules.

A further object is to provide a method for extending composition coatings with aggregate material and in measured quantities.

Another object is to provide a method for bringing together measured quantities of coating materials and aggregate particles, and to continuously form one or more layers comprising said materials on a suitable base.

'A further object is to provide a method for Fig. 1, and

producing a structure of composition material,

measured quantity of particulate material to the point of coating removal or in advance thereof, so that the same will be discharged by the distributor bristles with the coating material, and in a manner such that the individual particles of particulate material receive a coating thereof before being discharged.

These and other objects of the invention will in part be understood and in part be more particularly pointed out in the following description and in the claims taken in conjunction with the accompanying drawing, wherein Fig. 1 is a side elevation of apparatus embodying the invention;

Fig. 2 is a plan .view of the apparatus shown in Fig. 3 is an enlarged sectional view of the particulate feeding and coating apparatus shown in Fig. 1.

Referring to Figs. 1 to 3 inclusive, Fig. 1 shows a coating machine such as disclosed in my aforesaid copending application, now Patent No. 2,156,286, and which comprises a plurality of coating units l0 and H, each comprising a hopper I2, a driven rotatable roll I4 to feed a measured layer of coating composition and forming the bottom of the hopper, and a distributing member, for instance, a rotatable bristle impeller l6 operating on the fed composition and discharging a particle stream thereof on a receiving surface below. The units are suitably supported in a frame l8 by suitable brackets or other supporting means, more particularly illustrated in said prior application. An endless conveyor 20 is positioned below the coatingunits, preferably in close proximity to but out of contact with the distributor {l6 and serves to convey suitable base materialjli which may be a web of mineral surfaced composition roofing material or in-,, dividual shingle elements thereof, which have been made into blanks by a cutting roll 24, for

coating, by the. discharging coating streams] Where a web of material is fed, such may be sub-w sequently delivered in coated condition to a pull roll assembly 26, whereby the web may be passed into contact with a cutting roll 28 and severed into sections of desired size, and these delivered to a conveyor belt 30 for further operations.

In the operation disclosed in Fig. 1, the base material to be coated will receive one or two applications of coating composition, depending on whether one or both of the coating units are in operation. Thus, for example, upon passing under the first coating unit I 0, the base material will receive a base coating of the composition in the hopper of this unit, and on subsequently passing beneath the coating unit II, will receive a second coating. It will be understood that further of these hoppers may be positioned along the path of the conveyor 20, and additional coatings be applied to the base material. Likewise, instead of using tl.e composition as a coating, layers of suitable thickness may be formed of the composition upon the conveyor 20, and such layers removed to form various products, for example, where the composition is one of cement, suitable shingle slabs or wallboard might be produced.

-In these coating operations, it is sometimes desired to include certain aggregate or particulate material with the coating material or composition, and it is a feature of the invention to provide a method that will enable such material to be added to the coating composition from a separatesource of supply so that it becomes well mingled therewith, and such that substantially each particle of the aggregate becomes well treated with the composition. Moreover, the procedure to be described enables me to obtain a uniform distribution of the aggregate and provides all portions of the fed coating composition with their proper amounts of aggregate material. Examples of aggregate material that may be handled in accordance with this invention are, for example, comminuted fibrous, flocculent or granular materials such as asbestos, ground cork, mica flakes, graphite, powdered coloring pigments, crushed slate, tile or silica. One or more of these may be brought together with various coating compositions, for example, an argillaceous cement such as a hydraulic cement like portland or aluminate, water emulsions such as of bitumen, or phenolic resins, resinous molding compounds wetted with suitable solvents, casein compositions, rubber or latex in suitable solvents, and silicate coatings, for instance, soluble sodium silicate. Preferably, these compositions will be in a plastic or sludgycondition such that they may be fed by the character of hopper and feed roll apparatus disclosed in the drawing. ever, it will be understood that where these coat ings are of a more liquid character that suitable feed mechanism, for example, of the character disclosed in my application filed of even date herewith, may be substituted in lieu of the hopper l2.

In order-to feed the aggregate extending or particle core (hereinafter referred to as aggregate material) material, a suitable hopper 32 may be provided having a feed roll 34 forming the some instances, a guide such as a. chute 38 may be employed to control the point of application of the aggregate material. Also, sometimes it is preferred that the material from the hopper 32 reach the coating layer l8 somewhat in advance,

for instance, a short distance before contact by The latter is found desirable the distributor l6. where the operation is one to fully coat particles, such as when coated roofing granules are being made; also, when the aggregate material being fed is of a light character, so as to keep the Howsame out of the influence of the air stream of the impeller. Upon reaching the coating layer I8, the particles of the stream 36 come into the influence of the brush l8 and are beaten and well mingled with the coating and then discharged as by impelling against the base material 22 or conveyor 20, as the case may be. The described procedure assures an intimate co tact between the particles of the aggregate and the coating composition, so that the particles of commlnuted material are substantially individually coated with the coating composition before dis charging.

The guide 38 may be in the form of. a sheet metal plate supported by rocker arm 39 and secured thereto by bolts 40. The arm 39 may be clamped to a stationary support such as a rod 4|, by set screws 42. Obviously, in this manner the chute or guideway 38 may be adjusted to any suitable radial position. The plate 38 may also be provided with elongated slots 44 so that the discharge end of the guide may be somewhat adjusted in this manner. The guide plate may further be provided with one or more partition plates 46, where two or more different aggregates are being fed. The partition 48 is provided at its outer edges with flat under-fingers 48 carrying clamp screws 50. When the member 46 is used, it will generally be in the same relative position as the partition member or members 52 of the hopper 32 and the partition plate 54 of the coating composition hopper I2. The feed mechanism may also be provided with one or more baflie 'plates 56 supported between the side frames l8. These may be positioned to further guide the particle stream or to prevent outside influence on such stream of particles. Also, the impellers 5 may be covered by a suitable shield 58 to prevent throwing of the coating composition by this member.

The aggregate feed roll 34 may be driven by any suitable means, such as by a belt 63 and pulleys 62 and 64 secured respectively to the shafts of the rolls l4 and"'34. Power may be applied for rotating the coating composition feed rolls l4 and the distributing or discharge elements l6 by any suitable means, for example, a belt (not shown) engaging a pulley 68 carried upon the feed roll shaft'ltl of the coating unit I0. The impeller l6 of this unit may be driven by a set of gears 12 mounted on the shaft 10 of the coating feed roll and shaft I4 of the impeller IS. The impeller I6 and feed roll H of the coating unit H may be driven from the shaft 14 by means of cooperating gears I6. It is to be noted that the gears 12 and 15 are so arranged that the distributors l6 are driven at a higher speed than the feed rolls Hi. It is obvious that the specific type of driving mechanism for the various rolls may be varied as desired. A specific embodiment has been shown for purposes of illustration only. The impellers and also the feed rolls of both hoppers i 2 and 32,

may be driven by separate motors, if desired,.in

provided as there are coating units.

order to obtain any desired speed differential between these members.

It will be understood that while the aggregate feed unit 32 has been shown in the drawing only in connection with the coating unit II, a similar unit may be provided for the coating unit Ill. Moreover, it will be understood that as many of these aggregate feed mechanisms may be It may be seen that by properly controlling the speed of rotation of the roll 34, the rate of delivery of aggregat' imaterial to the coating carrying roll I4, may be] controlled. Likewise, the speed of the roll" l 4will control the rate of delivery of coating material. These speeds will be selected for the type of result that is desired, that is, whether the combined materials are to be formed, for instance, into a coating layer or into individually coated particles. It will be understood that the aggregate materials may be readily combined with the coating composition and in any density, and will be thoroughly beaten and mingled with the coating material before delivery by the impeller or other distributing device.

The described arrangement .is particularly useful for coating granules or other particles which it may be desired to provide with an encasing film or layer of coating material. For examplefit may be desired to coat individual roofing granules of a size between 8 and 12 mesh, such as are customarily used for surfacing asphalt roofing materials. To accomplish this, base granules or cores are placed in the hopper 32.and a suitable coating composition, for instance, a colored hydraulic cement composition, is placed in the hopper l2 of the coating unit' II. The rate of feed of the roll 34 will be controlled so that a proper proportion of base granules are fed to the layer 31 of coating material carried by the feed roll l4. In the operation, the granules will be brought into contact with the coating material and then discharged by the distributor or impeller 16 in a coated condition. The impeller IE will be of the bristle or spring filament type. During contact by the impeller, the base granules receive what is believed to be a rotary or spinning action whereby they are fully coated. By adjusting the viscosity of the coating composition, the speed of the bristle impeller 16 and the rolls l4 and 34, the point of application of the granules, as well as the amount of wipe of the brush bristles, the granules may be projected in a fully coated condition and coated to any desired extent and with coatings of desired characteristics. The coated granules may be deposited by the distributor [6 upon the moving conveyor 28, which may be in the nature of a screen or rubber belt of sufiicient length, and may be collected at a. subsequent point, for instance, by dropping into the collection tray 88.

Obviously, the distance to be traveled by the coated granules from the point of deposit to their point.of collection will depend upon the nature of the coating and any further operations which it may be desired to perform on the coated pieces before reaching the collection point. In certain cases it may be desired to apply the coated granules directly to a base material, for instance, the web 22 carried by the conveyor to provide an ornamental or weather surfacing therefor. Where the base material has received a prior coating layer from the coating unit III, the freshly coated granules may be de-- posited on such coating and be bonded thereto.

Suitable vibrators 82 may also be provided for keeping the coated granules agitated, where they are directly deposited upon the conveyor 28. The vibrators may be, for instance, of an electro-magnetic type and may be positioned against the under side of the conveyor belt as shown in Fig. 1. A similar vibrator 84 may be provided for the guide plate 38 of the aggregate feed mechanism. It will be noted that the impeller l6 may be provided with a baflle 86 in line with the partition 54 of the coating composition hopper so as to separate compositions of different. character as they are impelled on the web 22. The baflle 86 may also be provided with suitable vibrating means, for instance, that disclosed in my prior copending application, now Patent No. 2,156,286, aforesaid, to dislodge any composition which may adhere thereto. This means may comprise a pair of transverse rods 88, supporting the baflle 86. Springs 90, surrounding the rods 88 and engaging the frame l8, urge the baflies against stops carried by the rods. A pin 93 (Fig. 2) is slidably carried in the frame l8, and at one end bears against the baffle 86 and at the other end against a cam 94 which may be mounted, for example, on the shaft 96 of the impeller l6. As the cam 94 rotates, the pin 93 is caused to reciprocate transversely causing a corresponding movement of the bailie plate 86.

The apparatus of my invention may readily be used to deliver coating compositions containing considerable filler; and produce mastic forms on the conveyor 26 below. In some in.- stances, it may be necessary to heat the distributor IE or even the feed rolls l4, in which case suitable steam piping may be provided for such purpose through the center of the respective members, all as more particularly disclosed, for example, in Fig. 15 of my prior application (now Patent No. 2,156,286) aforesaid. In such an operation the coating may be, for example, a hot bitumen or any other character of congealable coating.

In operating the mechanism of Fig. 1, for instance, to coat a roofing web with a base cementitious composition and with a surface cementitious coating containing a fireproofing and strength provided aggregate, the following takes place: The hopper l2 of the coating unit [8 is provided with a base cement coating composition and the hopper l2 of coating unit "I I, with a coating of similar character but which may include some coloring material. The hopper 32 is provided with a supply of comminuted asbestos with or without further coloring material. The coating compositions in the hoppers l2 will preferably be in a plastic or sludgy condition. Power is supplied for rotating the feed rollsand distributing mechanism, and the rolls l4 each feed a predetermined layer of the cement composition from their respective hoppers to the point of contact of bristle impellers l6, by which the composition is applied in a particle stream to moving web 22 to reform a layer thereon. The secondary coating or surface coating provided by the coating unit II, will immediately followthe first or base coating provided by the coating unit l0, and. the former will carry with it a deposit of aggregate material from the hopper 32, which in this case will be asbestos fiber with or without a coloring aggregate. The aggregate will be dropped upon the secondary coating as it is carried in the roll l4 and slightly in advance of the distributor so that this material will be well coated with the cement composition before being projected against the base web. Essentially, continuous increments of the deposited layer are beaten to commingle the coating and particulate pieces and to coat the latter. In this manner, a structure is provided having a base cementitious coating and a surface colored coating carrying a fireproofing and strength giving aggregate. Where the base web is, for instance, an asphalt coated granule surfaced one, the force may be sufficient to cause the of rotation or motion shown in the drawing for the various moving parts are the preferred directions.

From the above description, it will be seen that I have provided novel methods for combining aggregate particles and coating compositions, and methods for forming individually coated particles. The disclosed embodiment of the invention has been set forth for the purpose of illustration only. It will be understood that many changes may be made and will suggest themselves to those skilled in the art Without departing from the spirit and scope of my invention, which is only to be limited in accordance with the following claims when taken in conjunction with the prior art. 7

I claim:

1. In the method of treating particulate material, the improvement comprising feeding coating material and a particulate substance from separate sources of supply, forming a layer of said coating material including amultiplicity of pieces of said particulate substance, and beating continuous increments of said layer to commingle said coating and particulate pieces and coat the latter.

2. In the method of treating particulate material, the improvement comprising feeding a plastic coating material and particulate substance from separate sources of supply, forming a layer having said coating and a multiplicity of pieces of said particulate substance applied in superposed relation, and beating continuous increments of said layer to commingle said coating and particulate pieces and coat the latter.

3. In the method of treating particulate material, the improvement comprising feeding plastic coating material and particulate substance from separate sources of supply, forming a layer comprising said plastic coating and particulate substance applied in superposed relation and comprising predetermined amounts of said plastic coatingmaterial and particulate substance and beating continuous increments of said composite layer to commingle said coating and particulate substance and coat the pieces of particplicity of pieces of said particulate substance upon said layer and beating continuous increments of said composite layer to commingle' said coating and particulate pieces and coat the lat-.

ter. J g

5. In the method of coating roofing granules with a plastic coating the improvement comprising forming a layer of plastic coating material,

adding a multiplicity of individual granules to a surface of said coating layer, giving the granules of said composite layer a substantially rotary motion whereby to coat them with said 'fiber, and beating continuous increments of said layer to commingle said cement composition and mineral fiber pieces and coat the latter.

7. The method of treating particulate material and surfacing a base therewith comprising feeding plastic coating material and particulate substance from separate sources of supply, forming a layer having said coating and a multiplicity of pieces of said particulate substance applied in superposed relation, beating continuous increments of said layer to commingle said coating and particulate pieces and coat the latter, and projecting a stream of the coated particulate material upon a base having relative motion with respect thereto to form a surfacing thereon.

8. The method of treating particulate material with plastic and forming a layer product therefrom comprising feeding plastic coating material and particulate substance from separate sources of supply, forming a layer having said coating and a multiplicity of pieces of said particulate substance applied in superposed relation, beating continuous increments of said layer to commingle said coating and particulate pieces and coat the latter, projecting a stream of the coated particulate material upon a re ceiving surface having relative motion with respect thereto, and forming a layer of said material of substantial thickness.

9. The method of treating a particulate aggregate with plastic material and applying the same to a receiving surface, comprising withdrawing a measured layer of plastic material from a source of supply, superposing a measured amount of solid particulate aggregate upon said plastic layer, beating continuous increments of said composite layer to commingle said plastic material and pieces of particulate aggregate, and impelling a stream of said commingled material upon a receiving surface. I

10. The method of treating particulate material with a plastic coating material comprising substantially continuously feeding coating material and particulate substance from separate sources of supply, substantially continuously moving a layer of the coating with respect to a stream of said'particulate substance, substantially continuously superposing a multiplicity of pieces of said particulate substance upon said coating layer, substantially continuously beating increasing increments of said composite layer to commingle said coating and particulate pieces,

and distributing coated particulate pieces of said rial comprising feeding a stream of plastic coating to a distributing position, adding solid particulate material to the plastic coating at said distributing position, commingling said coating and particulate material and spinning the pieces of particulate material whereby to provide them with a substantially continuous surfacing of said coating, throwing said coated particulate pieces into space, and collecting the coated material upon a surface having lateral motion with respect thereto. p

12. The method of treating a particulate aggregate with coating composition and applying the same to a receiving surface comprising forming a layer of the plastic coating material, moving said layer to a distributing position feeding a a stream of particulate aggregrate material to said coating layer in advance of said distributing position, commingling said aggregate material and coating, and impelling a particle stream of the commingled material upon .a receiving surface to form a substantially continuous layer thereon.

ous increments of said composite layer to com- 20 mingle said cement and granular material and coat said granular material with said cement. and, before said cement has set, projecting said coated granular material upon a base having relative motion with respect thereto whereby to bond said granular material to said base.

14. The method of treating particulate aggregate material with coating and superimposing a plurality of coatings certain of which include said aggregate comprising feeding a plurality of coating layers, surfacing selective layers with solid particulate aggregate material, l'ieatingcontinu-v ous increments of said surfaced coating material to comminglesaid coating and pieces bf particulate aggregate and coat the latter and beating continuous increments of said unsurfac'ed coat-- ing, impelling particle streams of the beaten nortions of said layers against a surface having relative motion with respect to said streams, and projecting said streams such that-they produce superposed laminations on said surface.

' NORMAN P. HARSHBERGER.

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