US2681637A - Coating apparatus for applying a resin in particulate form - Google Patents

Description

G. G. SIMPSON COATING APPARATUS FOR APPLYING June 22, 1954 A RESIN IN PARTICULATE FORM 2 Sheets-Sheet 1 Filed Dec. 4, 1950 INVENTOR GEORGE G. SIMPSON ATTQRNEY June 1954 e. G. SIMPSON 2,681,637

COATING APPARATUS FOR APPLYING A RESIN IN PARTICULATE FORM 2 Sheets-Sheet 2 Filed Dec. 4, 1950 INVENTOR GEORGE G. S/MPSON B & M)

ATTORNEY Patented June 22, 1954 COATING APPARATUS FOR APPLYING A RESIN IN PARTICULATE FORM George G. Simpson, Laurel, Miss., assignor to Masonite Corporation, Laurel, Miss., a corporation of Delaware Application December 4, 1950, Serial No. 199,048

2 Claims. (Cl. 118-308) This invention relates to the application of materials to surfaces, and more particularly to a coating apparatus for uniformly applying discrete solid particles, e. g. resins and the like, to the surface of sheet materials.

An object of this invention is an apparatus for applying discrete solid particles to surfaces. A further object is a coating apparatus for uniformly applying discrete solid particles, e. g. resins, to the surface of sheet materials. Yet a further object is an apparatus for applying these particles to the surface of sheet material and fusing them into a uniform film for coating the surfaces of sheet material such as hardboard and the like. Other objects will be apparent from the following description.

The above and other objects are accomplished according to this invention broadly by providing and employing an apparatus comprising a cylindrical casing with its axis horizontally disposed and the chamber within the casing closed at both ends and opened at the top and bottom, a feed supply means attached to the casing over the top opening, a feed diffuser means fed through the bottom opening, a shaft axially journaled in the ends of the casing, bristles which radiate from said shaft to the walls of said chamber and to the feed diffuser so as to provide a rotary brush for expelling theparticles which will make up the coating, means for driving said brush and means for conveying the material to be coated. Preferably the coating apparatus includes means, e. g. an air hammer, for vibrating the casing containing the brush. If the coating material applied is to be heated or fused, means for supplying heat is also provided.

A preferred embodiment of this invention will now be described in more detail with reference to the accompanying drawings which form a part of this application. Like reference numerals are used to indicate like parts.

Referring to the drawings generally:

Fig. 1 isa side elevation. in. partial section showing an apparatus embodying the general aspects of the invention. I j Fig. 2 is a cross section view along the line 22 of Fig. 1 showing the cylindrical casing, the rotary brush therein, the feed diffuser screen beneath the chamber, and the sheet material in position for being coated.

Fig. 3 is a cross section view along the line 3-3 of Fig. 1 showing the burners for fusing the coating material and the sheet material, and indicating the coating which has been. applied and fused on the sheet, and also showing the means for conveying the sheet material, and

Fig. 4 is a cross section of a modified form of support for the diffuser screen. i

The cylindrical casing l of sheet metal or the like is arranged with its axis horizontal, and is preferably of length substantially equal to the width of the surface to be coated and extends transversely thereof. The chamber la in the casing is closed at its ends 2. The casing is provided with a top inlet opening 3 and a. bottom outlet opening 4. These openings are of about the same length as the casing. An air hammer or hammers 5 vibrates the casing l and prevents caking or bridging of the resin particles. A feed hopper 6 supplies coating material to the chamber l a through opening 3 and has an adjustable feed regulating shutter I in its throat. A feed diffuser screen 8 is disposed across the opening 4 and the particles of coating material are delivered through the openings of the screen on to the sheet being coated. The delivery thereof is effected and controlled by a rotary brush comprising the shaft 9 and bristles I0 whose points contact and engage the screen 8. The rotary brush will have drive means (not shown), e. g. an electric motor preferably with speed control. A chute l5 conveys any spillage of the particles of coating material to the col lecting receptacle I6.

The heating means H, e. g. a bank of gas burners, beneath which the sheet with particles of coating material thereon is passed fuses the originally discrete particles l2 on to the surface of the sheet material I 3, forming an adherent film or coat [3a thereon. Conduit I1, header l8 and aspirators l9 supply gaseous fuel for heating the radiants 20. Conduit 2| supplies compressed air to the air hammers 5.

The coating apparatus is supported by the table 22 having legs 23. Conveying means, e. g. driven table rolls I 4, convey the sheet material I3 to be coated beneath and beyond the feed diffuser 8 as indicated by arrow on Fig. 1. After leaving the conveyor comprising the rolls II, the sheet material carrying the resin particles is passed beneath the radiants 20 or other heat source by means of a metal heat-resisting conveyor comprising sprockets 24 and chain 25 from which the coated sheets are delivered. Both conveyors are flat and level to prevent the boards or sheets getting out of level.

As shown in Fig. 4 the screen 8 may be attached removably and replaceably to casing I as by securing it to a framepiece 8a and attaching such part Ba to the casing by screws 8b. When the particle size of resin is changed the feed screen with corresponding. size openings can thus be used. To support the screen from beneath, cross bars 80 can be provided at suitably spaced intervals. The framepiece 8a consists of parallel angle-shaped members which extend across the width of the cylindrical casing I, The opposed faces of the angle-shaped members extend downwardly from the feed diffuser 8 and serve to guide or restrict the flow of the discrete resin particles and to direct them over a limited area of the sheet material to becoated.

In starting the coating apparatus the conveyor table rolls l4 and the. sprocket chain 25 are started, the gas burners H are ignited, the hoping the adjustment stage the resin used passes into the chute i and is recovered in receptacle it: for reuse. After the starting adjustments have been made and the desired temperature has been reached by adjustment'of the gaseous fuel supply, hardboards i3 are placed on the" conveyor table rolls: i l with the ends of the boards abutting each other. These rolls convey the boards beneath the casing i. The bristles force resin particles through the feed diffuser screen 8, and to improve the forcing action the shaft 9 may be made vertically adjustable to compensate for wear of the bristle tips. The particles of resin fall onto the top surface of the boards, forming a remarkably uniform layer over the entire surface area of the boards. The boards with their supernatant layer of resin particles pass under the gas burners i adjacent to the resin applying apparatus. The heat from the burners fuses the resin andcauses its particles to coalesce and adhere to the surface of the boards in, the form of a continuous and very uniform film. Shortly after passing from beneath the burners, the film isnon-tacky.

The thus coated boards may be used as a finished product at this point if only a sing-le'ply having a protective film is desired. If it is desired tc form a laminated product,.the coated boards may be laminated immediately (e. g. in a hot press) or they may be stored any length of time desired before laminating. If both surfaces of. the boards are to be coated, they may be run through the coating apparatus a second time with the uncoated surface up.

A remarkable feature of this invention is the high degree of uniformity of the coating applied. This especially important in coating sheets to be laminated in order to give a uniformly strong bond and to prevent the possibility of uneven moisture content in the sheets resulting from the I 7 heat driving off moisture from thinly coated areas during fusion of the coating material, or from the evaporation or migration of moisture during hot pressing of the coated sheets into a laminated product.

While details of the invention have been disclosed above in showing the preferred construction and operation of the apparatus, modificaregulator 1 renders a single hopper adaptable for use with many types of coating materials. In some coating operations it is not desired to heat the coating material applied. In such case, of course, heating elements are not used. If heat is needed other sources besides gas may be used.

While Tampico bristles (vegetable fiber bristles) have given very good results, animal bristles, metallic bristles, synthetic bristles and other types of fiber bristles are applicable. Although the screen of wire mesh 8 works well as a feed diffuser, any suitable perforated member may be employed.

The circumferential speed of the bristles, the linear speed of the material being coated, the type discrete solid particles used as 'a coating material, the temperature employed in. heating the coating material, the amount of coating material applied, the particular type and mesh size of. the feed diffuser screen, and other variables may be regulated, varied or modified as desired. These and other regulations and modifications are withinthe' skill. of the artisan.

Although this invention been described in detail with reference to coating hardboards, it is applicable to applying coating materials to the surfaces of materials in'general, such as e. g. veneers, lumber, metal sheets, paper.

It is to be understood that the invention is not to be limited to specific embodiments thereof except as defined in the claims.

' I claim:

1. A coating apparatus for applying a resin in the form of discrete solid particles uniformly on the surface. of a sheet material which comprises a horizontally disposed cylindrical casing having a chamber therein closed at both ends and open at the top and bottom, means for vibratin the casing, a hopper for feeding the resin to the-container attached to the casing over the' top openmg, means attached to the throat of the hopper for regulating the feed of resin to the chamber, a feed diffuser screen fitted into the bottom casmg opening and attached to the casing by means of parallelv angle-shaped members with the opposed faces of said angle-shaped members forming downwardly extending guide members for the discrete resin particles, a shaft axially journaled in the chamber, bristles which radiate from said shaft to contact the feed diffuser, the tips of said bristles forming an essentially continuous pethe form of discrete solid particles uniformlyon the surface of a sheet material which comprises a horizontally disposed cylindricalv casinghaving a chamber therein closed at both endsrand open at the top and bottom, an air hammer for vibrating thecasing, a hopper for feeding the resin to the container attached to the casing over the top opening, means attached to the throat of the hopper for regulating the feed of resin to the chamber, a feed diffuser screen fitted into the bottom casin opening and attached to the casing by means of parallel angle shaped members with the opposed faces of said angle-shaped members forming downwardly extending guide members for the discrete resin particles, a shaft axially journaled in the chamber, bristles which radiatefrom said shaft to contact the feed diffuser, the tips of said bristles forming an essentially continuous periphery substantially coex- 15 2'557'561 tensive with the inner surface of said cylindrical casing, means for driving said shaft, and means for conveying the sheet material being coated.

References Cited in the file of this patent UNITED STATES PA'IENTS Number Name Date 465,815 Claus Dec. 22, 1891 841,685 Harris Jan. 22, 1907 1,659,179 Wilson Feb. 14, 1928 1,904,591 Wilson Apr. 18, 1933 2,112,759 Boyer Mar. 29, 1938 2,211,435 Peterson Aug. 13, 1940 Powers June 19, 1951

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