US2351271A - Method of and apparatus for depositing films - Google Patents

Description

`Fune 13, 1944.

c..w. LEGUILLON 2,351,271

METHOD OF AND APPARATUS FOR DEPOSITING FILMS Filed NOV. 27, 1940 s@ @11% t 74 imma HM Patented June 13, 1944 UNITED STATES PATENT OFFICE METHOD F AND APPARATUS F03 DEPOSITING FILMS Charles W. Leguillon, Akron, Ohio, assigner to The B. F. Goodrich Company, New York, N. Y., .a corporation of New Yorky Application November 27, 1940, Serial No. 367,436

dry a lm of the material upon the drum. Such' a procedure has not been successful in producing a uniform film of material especially where the liquid dispersion has been sensitive to temperature or to humidity or other atmospheric conditions. Such liquids often have been found to scum over or coagulate in the presence of the atmosphere,.so that coagulated scum particles, or foreign particles such as dust settling in the tank have been present in the deposited film.

The present invention aims to overcome or avoid the difllculties encountered and in the prior procedure to provide a novel method and apparatus for depositing uniform lrns or coatings upon a movable surface. The term film as-used herein is intended to embrace both independent films and coatings or strip or sheet material, unless otherwise stated.

The principal objects of the invention are to provide uniformity of product, to avoid or elimi- I nate waste, to provide for continuous manufacture of film material, to provide simplicity of equipment, and to provide convenience of operation.

A further object is to provide for avoiding or reducing to a large extent the depositing of objectionable particles on the film as it is formed.

Of the drawing Fig. 1 is a cross-sectional elevation of the apparatus constructed according to and embodying the invention, parts being broken away.

Fig. 2 is a detail plan view of the spreading roll of the apparatus.

Fig. 3 is a detail view of the drum, parts being broken away.

In accordance with the invention there is provided an upwardly directed constantly owing stream of dispersed composition and a constantly moving depositing surface moving through the flowing material so that a constantly uniform and fresh supply of clean material is always at the position of deposit, and the deposited film is free from dirt and scum particles by reason of such constant flow of fresh material.

The invention is best illustrated lby referring (ci. 1x3-15) to the drawing which shows the apparatus as provided for the formation of a wide sheet of thin material, although, if desired, strip or sheet material may be coated, ora lm may be deposited Y upon a narrow traveling surface such as a wire.

The .numeral Il designates a rotatable drum having hollow trunnions Il, I2 bywhich it is rotatably supported in bearings I3 by a suitable stationary frame I4. For convenience 'of controlling the temperature the drum is provided with a cylindrical wall l5 closely spaced below its outer wall I5 to provide a thin space l1 thereabetween through which a heating or cooling fluid may be circulated at a relatively high'rate of travel. An inlet pipev Il communicates with the space through a swivel pipe connection I9 and a pipe extending through one of the hollow trunnions. An outlet pipe 2l'is similarly connected with the space through a swivel conne9tion\22 and a pipe 23 extending through the other trunnion. By making the space I1 relatively thin, rapid circulation of uid therethrough is accomplished and accurate heat control is therefore possible. A sprocket 24 is fixed to one of the trunnions and is driven by a chain 25 from any convenient source of power (not shown).

For supplying a constant ow of the dispersed material to be deposited on the face of the drum, a stationary frame is mounted below the drum and is provided with vertical bearings 3l, 32, 33, 34 in which vertically disposed shafts 35, 36 are rotatably mounted. The shafts are screw threaded between their bearings, as at 31, 38.

Collars 39, 40 are ixed to the upper ends of the shafts and sprockets 4|, 42 to their lower ends for retaining the shafts in their bearings. Sprockets 4I, 42 are connected by a chain 43 so as to op'- erate in unison. A bevel gear fixed to shaft 36 meshes with a bevel gear 45 ixed to a crank shaft 46 having a bearing in the frame 3B. A crank 41 is fixed to shaft 46 for the purpose of rotating both shafts 35, 36. A jacketed sump 48 has threaded ears 49, 50 adapted to engage the threads 31, 38 of the shafts. The arrangement is such that the sump may be raised or lowered at will by means of crank 41 with relation to the drum I0.

Located within the sump 48 but spaced from its inner wall 5I is a trough shaped manifold 52. A nozzle 53 is provided therefor and terminates at its apex in an orifice 54 extending parallel'to the axis of the drum.

The liquid dispersion to be deposited on the drum is drawn from 'a supply `container (not shown) by a rotary pump B0 through a pipe 8| and is dischargedthrough avertical pipe 62 to the manifold I2. a HD ioint being formed in the pipe I2 to permit vertical adjustment of the manifold l2. Overflow from the nome' 53 is collected by the sump 48 and after passing a lter Mc. is drawn therefrom through a drain pipe 6l by a rotary pinnp 6I which returns it to the supply container for further use so that the filtered dispersion is circulated over and over. A slip joint 68 is provided in the drain pipe to permit vertical adjustment of manifold 52.

For the purpose of maintaining the temperature of the dispersion at the temperature desired for reuse, the sump extends closely about the manifold B2 and is jacketed, as at Bl, the jacket the pump and motor shafts. The pump 65 is adapted to be driven at slightly faster speed than pump to prevent any overflow of the sump IB.

As the rotating drum l0 has its surface close to the orifice 54, the dispersed material flowing from the orice It is continuously flowing under a uniform head, in contact with the drum surface and is deposited thereon. 'I'he deposited material is dried as the drum rotates and for the purpose of removing all solvent vapors and of' protecting the deposited film from dust and currents, a hood Ill is provided. 'I'his hood encloses the greater part of the drum surface and has an outlet pipe Il for carrying away the vapors. The hood assists in reducing heat radiation from the drum.

For removing the deposited nlm of dried material a pair of driven rolls 82, 83 are rotatably mounted in spaced apart relation on the frame il. A sprocket Il fixed to roll 83 is driven from a sprocket U5 fixed to the drum I'Ilthrough a chain 86, and roll I3 drives roll 82 through gears 81, 88 xed to the rolls respectively. The arrangement is such that rolls B2 and 83 are driven at the same surface speed as drum I0. A windun roll IS is rotatably mounted on a swing frame 9| pivoted on the frame i4, as at 9|, in a position to contact with roll 83. As the leading end of the film is wrapped about roll 89 it builds up by accumulation of film and its arm 9|! swings away from roll I3. The pivotal axis 9| is to the left of a vertical `plane through'the axis of roll -89 in Fig. 1 so that the weight of the roll causes it to bear against roll A counter-balance 92 is provided to adjust the pressure of the rolls against each other.` The shaft 9| which acts as a pivot for arm l.. to which it is xed, has a v grooved pulley Il fixed thereto. A rope-94 extends through the groove and has a swing treadle $5- flxed thereto at one end and a weightv 96 fixed to the other end. The treadle is pivotally mounted on the frame il as at 91. 'Ihe arrangement is such that the weight counterbalances i the treadle and that depressingv the treadle lifts is provided between rolls- 8l and 8B and located above a plane drawn tangent to the rolls with the convex side of the'spreader facing toward roll 89. 'I'he arrangement is such that a sligh tentering of the illm occurs.

The operation of the apparatus is as follows: The liquid material isrforced by pump 80 to the oriilce 54 rwhere it is forced up in a projected flow normally taking a convex meniscus form extending substantially tangent to the curved surface of the drum when not disturbed by the drum. By manipulating the crank 41 the orifice may be raised with respect to the drum so that the drum surface intersects the, crest of the ow. 'Ihe drumis rotated and material is deposited on the face thereof.

The superior results of the invention apparently are explained, at least in part, by the action wherein the liquid copiously flowing from the orifice and overflowing it both forwardly and rearwardly, aSjshown in Fig. l, is in uniform and constant contact with the surface of the drum, the surfacetension of the liquid is never broken and the newr material is supplied beneath the tension surface which extends over the material previouslyl deposited and downwardly along the overflow lstream thereby avoiding any breaking ofsurface tension. The material is therefore deposited in the "direction of its natural ow with the least tendency for eddy currents or waves to form,and any scum or deposit is naturally carried-bythe overflow away from the drum. At the'same time the travel of the deposited material is in a generally upward direction so that no ow wrinkles are formed in the sheet. By use of the invention the use of a static liquid surface is eliminated and deposit from a flowing-liquid is provided.

The' deposited film rotates around the drum and its solvent evaporates and passes from the hood while the dried material is wound from the drum onto the roller 89.' The apparatus may be adjusted by means of crank 41 so as to cause the convex surface of the drum to contact with the liquid over -a greater or lesser arc to change the time and area of `contact with the liquid at the slot providing adjustment of the deposit.

Due to excessive flow from pump 80, the liquid flows from the orifice and in to the sump, providing a constant supply of fresh liquid and preventing deposit of dried material or of dust particles. The jacketed Asump prevents cooling of the liquid and by its close confinement of the orifice prevents cooling ofthe nozzle and rapid evaporation of solvents, sov that the material is always ready for furtheruse.

The ow of the pumps t0, 6l may be regulated to means of `a well known variable speed drive, such as the ."Reeves between the motor 'I0 and the pumps, or by use ofgalvariable speed motor.

The apparatusv is particularly useful in forming films of material such as polymerized vinyl halides from solutions' or dispersions thereof or of other materials which Vare particularly sensitive to atmospheric conditions or change .of temperature in the liquid state.

While the apparatus is shown vas depositing the same apparatus', maybe .used for depositing a film upon a suitablyjfed sheet or strip of material which may if desired be fedA over the surface of the drum. and while the drum is shown as having a plain surface for forming a smooth film, the drum surface may be engraved to form a nlm havinga design. While the drum asshown is for providing a fiat wide sheet or film, by passing a wire or other strip about the drum surface a thread of material may be formed thereon. Where it is desired to provide a lm on a sheet of fabric or other material by the deposit of a plurality of coats, the sheet of fabric or other material may be passed through the apparatus a number of times.

Variations may be made without departing from the scope of the invention as it is dened by the following claims.

I claim: v v

1. Apparatus for progressively depositing a continuous film of material from a liquid dispersion thereof upon a surface, said apparatus comprising means for moving the surface progressively past a station, an upwardly directed nozzle located at said station below the path of said surface and in spaced relation and normal thereto for accommodating a copious fiow of the dispersion against said surface and overflow both forwardly and rearwardly of the nozzle with respect to the direction of surface movement, and means for projecting a copius continuous ow of said dispersion through said nozzle in continuous contact with said surface and in an excess to provide said overflow.

2. Apparatus for progressively depositing a continuous film of material from a liquid dispersion thereof upon a surface, said apparatus comprising means for moving the surface progressively in a curved path past a station to present the surface in a downwardly facing convex position at the station, an upwardly directed nozzle at said ystation below the path of said surface and in spaced relation and normal thereto for accommodating a copius flow of the dispersion against said surface and overow both forwardly and rearwardly of the nozzle with respect to the direction of surface movement, and means for projecting a copius continuous now of said dispersion through said nozzle in continuous contact with said surface and in an excess to provide said overow.

3. Apparatus for progressively depositing a continuous film of material from a liquid dispersion thereof upon a surface, said apparatus comprising means for moving the surface progressively past a station, an upwardly directed nozzle located at said station below the path of said surface, said nozzle having an orifice extending across the path of said surface and in spaced relation and normal thereto for accommodating a copious ow of the dispersion against said surface and overiiow both forwardly and rearwardly of the nozzle with respect to the direction of surface movement, means for providing a copious unbroken flow of said dispersion through said orifice and outwardly and downwardly over said nozzle in both said directions to maintain the nozzle at the temperature of the liquid and prevent solidiflcation of material at the nozzle, and means for adjusting the relation of said surface and said nozzle to immerse said surface at said station in the crest of said flow.

4. Apparatus for progressively depositing a continuous nlm of material from a liquid dispersion thereof upon a surface, said apparatus comprising means for moving the surface progressively past a station, an upwardly directed nozzle located at said station below the path of said surface and in spaced relation and normal thereto for accommodating a -copious ow of the dispersion against said surface and overflow both forwardly and rearwardly of the nozzle with respect to the direction of surface movement, said nozzle having an orifice extending across thev path of said surface, means for providing a copious unbroken iiow of said dispersion through said orifice and outwardly and downwardly over said nozzle in both said directions to maintain the nozzle at the temperature of the liquid and prevent solidification of material at the nozzle, means for adjusting the relation of said surface and said nozzle to immerse said surface at said station in the crest of said flow, and means substantially enclosing the space surrounding the depositing area of said surface and said nozzle to minimize loss by evaporation of solvent from said flow of liquid.

5. Apparatus for progressively depositing a continuous film of material from a liquid dispersion thereof upon a surface, said apparatus comprising* means for moving the surface progressively past a station, an upwardly directed nozzle located at said station below the path of said surface and in spaced relation and normal thereto for accommodating a copious flow of the dispersion against said surface and overflow both forwardly and rearwardly of the nozzle with respect to the direction of surface movement, said nozzle havingan orifice extending across the path of said surface, means for providing a copious unbroken flow of said dispersion through said orificeand outwardly and downwardly over said nozzle in both said directions to maintain the nozzle at the temperature of the liquid and prevent solidification of material at the nozzle, means for adjusting the relation of said surface and said nozzle to immerse said surface at said station in the crest of said flow, and means for heating said surface.

6. Apparatus for progressively depositing a continuous lm of material from a liquid dispersion thereofupon a surface, said apparatus comprising an upwardly directed nozzle normal tosaid surface having an orifice for directing a Aow of said liquid dispersion. means for providing a copious unbroken flow of said liquid through said vorifice and outwardly and downwardly over said nozzle both forwardly and rearwardly of the nozzle with respect to the direction of surface movement to maintain the nozzle at the temperature of the liquid and to prevent solidication of material at the nozzle, a deposit-receiving surface, and means for feeding said surface progressively past said nozzle through the crest of the liquid dispersion flowing therefrom.

7. The method of progressively depositing a continuous film of material from a liquid dispersion thereof which comprises providing an upwardly directed flow of said liquid dispersion from a nozzle in suii'icient volume to overflow said nozzle both forwardly and rearwardly with respect to the direction of surface movement, continuously maintaining such overflow to provide a laterally unsupported flowing pool thereover, and progressively feeding a deposite-receiving surface `through said pool to progressively form a deposit of dispersion thereon.

GHARLES W. LEGUIILON.

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