US2447374A - Method of applying coating materials - Google Patents

Description

I- 1948' JQS. SMYSVER 2,447,374

METHOD OF APrLYIgc; Comma uumnns Original Filed April 25, 1954 3 Sheets-Sheet 2 yjl.

I NVEN TUR Aug. 17, 1948. .LS. SMYS ER IETHOD OF APPLYING comma u'rnanns Original Filed April 25, 1934 3 Sheets-Shut 3 INVEN run Jmzs 62 3017550, Br 604M115 7kw'r (m/0; firm/m.

* Patented Aug. 17, 1948 UNITED STATES PATENT OFFICE METHOD OF APPLYING COATING MATERIALS Continuation of application Serial No. 722,288, April 25, 1934. This application October 25, 1939, Serial No. 301,294

2 Claims. 1

This invention relates to a method of applying particles and various forms of comminuted materials to a base member, and to the resultin! product.

This application is a continuation of the copending application of James S. Smyser, Serial No. 722,288, filed April 25, 1934.

The principal objects of the invention are to provide a novel method for applying particles and finely divided materials, such, for example, as flock, linters, and the like fibrous material, abrasive particles, etc., to one or more surfaces of a base member, such as a piece of sheet material; to provide means for controlling the manner and rate of application or disposition of the particles so as to obtain a uniformly coated product having predetermined characteristics; and to provide means whereby unlimited lengths of sheet material may be coated efliciently and progressively, on either or both sides, more uickly, densely, uniformly and cheaply than by any apparatus and/or method heretofore used.

Other objects of the invention are to provide a strong and flexible product having a dense, homogeneous, villous finish simulating the appearance of either suede or a pile fabric; and to provide a finish of any desired density wherein the major portion of the fibers are disposed at substantially the same angle relative to the surface of the base sheet with their ends firmly embedded in an adhesive coating carried thereby.

Further objects relate to the mode of operation of the method, and will be apparent from a consideration of the following description and accompanying drawings which exemplify different embodiments of the invention.

In accordance with the present invention the surface (or surfaces) of the base member, or article to be coated is first rendered adhesive, as for example by the application of a suitable cementitious material, such as rubber cement, wax, paramn, glue, or the like adhesive. When thus coated the base member is passed through an electrostatic field set up between one or more pairs of oppositely charged electrodes, and during its passage through the electrostatic field the par-' ticles to be applied are carried in a uniformly dispersed formation into the field either by gravity, a current of air, or in any other suitable manner.

Preferably the particles being conveyed to the field are charged in any suitable manner with the same charge as that of the electrode projecting them against the base member, and to this end they may be passed through a metallic screen or the like member which is connected in the circuit of the projecting electrode. When thus charged, the particles, upon entering the electrostatic field are projected against the adhesive surface of the base member more uniformly and efiiciently, and with much greater force than would otherwise be possible. Furthermore, the individual particles are more effectively aligned in the direction of the lines of force of the electrostatic field and, due to the increased force with which they are projected against the surface of the base member, are more deeply and firmly embedded in the adhesive surface of the base member. Moreover, movement of the charged particles toward the adjacent or projecting electrode is greatly minimized, if not substantially eliminated, and consequently considerable waste is eliminated and the eiiiciency of the method and apparatus is appreciably increased.

The construction and arrangement of the electrodes is such as to provide an electrostatic field of uniform flux density which extends across the path of the surface of the article to be coated and at an angle to its path of travel. The position of the individual particles relative to the surface of the base member may be controlled and/or varied by adjusting the relative position of the electrodes so as to attain the desired direction of the lines of, force of the electrostatic field relative to the surface of the base member. To this end one or both of the electrodes may be adjustably mounted so that their position relative to each other may be varied.

The electrostatic field may be produced by a suitable source of potential such as aKenotron or the like alternating current rectifier, a static machine, meohanical rectifier, or any other source which may be susceptible to control. The potential impressed upon or across the electrodes may vary within wide ranges, depending upon the character of the material to be deposited, the desired rate of deposition, etc., and the usual types of control instrumentalities maybe employed to provide an electrostatic field of the desired characteristics.

The rate 'of deposition or application may be so controlled as to produce a coated product of any desired density by varying the quantity of particles supplied, the rate of travel of the base member through the field, and/or the electrical characteristics of the field, i. e., the flux density, voltage across the electrodes, etc. To this end suitable means may be employed to control the rate of delivery of the particles and the rate of electrical circuits or circuit to provide for the adjustments necessary to attain an electrostatic having a series of pointed members or prongs secured thereto and arranged as shown in Fig. 2.

The electrodes are arranged in pairs -lll, 4| and l2, l3 and may be connected to any suitable source of potential as hereinafter described. The

elements of each pair are disposed on opposite field suitable for the application or deposition of the particular type of material to be applied.

In the drawings:

Fig. 1 is a diagrammatic side elevation, in section, showing a suitable apparatus;

Fig. 2 is a diagrammatic plan view of the apparatus shown in Fig. 1, the means for feeding the particles to be applied being omitted;

Fig. 3 is a schematic diagram illustrating one arrangement of the electrical connections;

Fig. 4 is a graphic representation of a pulsating current used in connection with certain forms.-

of apparatus herein shown Fig. 5 is a fragmentary section showing a piece Fig. 11 is an enlarged fragmentary section 1 showing a specimen of sheet material after being coated in accordance with the present invention.

The embodiment shown in Figs. 1 and 2 comprises a coating apparatus ID, a deposition apparatus designated by the numeral II, and a winding mechanism l2. The coating apparatus may be of any type suitable for applying a coating of adhesive such as rubber cement, wax, glue, paraflln, or the like cementitious material to one or both surfaces of a base member or sheet material S, and as here shown comprises atank or trough l9 having guide rolls l5, I1, 20, 2| and 22 to conduct the sheet material through a fluid bath 23 of suitable adhesive, and squeeze rolls 24 and 25 to remove excess adhesive and distribute the coating uniformly over the surfaces of the sheet S. The temperature and fluidity of the bath 23 may be controlled in any suitable manner as by steam coils 26. The winding apparatus l2 may be of any conventional form and is here shown as comprising a. guide roll [3, a winding drum l4, and a reel 15, upon which the coated sheet material is wound. Suitable means (not shown) may be provided to regulate the speed of the winding drum l4 and thus control the rate of travel of the sheet material S.

The deposition apparatus H comprises a boxlike structure or housing preferably having uprights or walls of suitable electrical non-conducting material which define the deposition zone metallic bar secured to a suitable support and sides of the path of travel of the sheet S and are preferably inclined at an angle to its line of travel so as to provide an electrostatic field which extends diagonally across the path of movement of the sheet S. The purpose of this inclined arrangement is to insure a more even coating when the comminuted material is fed to the electro static field from the top.

Suitable means are provided to conduct the material to be deposited on the sheet S into the electrostatic fields set up between each pair of electrodes and to this end hoppers 5|! and 51 may be arranged directly above electrodes 40, I and 42, 43, respectively. If it be desired to coat one side of the sheet S only, the hoppers may be arranged to discharge the coating material into a zone between the projecting electrode and surfaceof the sheet to which the material is to be applied. Where both sides of the sheet S are to be coated, the hoppers may be arranged to discharge the particles on'both sides of the sheet 8 or, if desired, one hopper may be arranged to discharge the material on one side of the sheet and the other hopper on the opposite side, the particular arrangement depending upon the connections of the electrodes for the most effective results. I

At some convenient location between the hoppers 50, SI and the electrostatic fields, there may be provided means for imparting an electrostatic charge to the particles to be applied and to this end metallic screens 52 and 53, or the like, may be mounted beneath the discharge openings of the hoppers and 5|, as shown in Fig. 1, or, if desired, these screens may be integral with the hoppers. Each of the screens are connected to the negative electrode or to the negative terminal of a suitable source of potential so that the particles as they emerge from the screens have the same negative charge as that of the negative or projecting electrode. Suitable means (not shown) may be employed to control the rate of delivery of the particles from the hopper so that the density of the coating applied to the sheet material may be varied as desired.

Fig. 3 shows how the electrodes maybe connected for use with a pulsating current (graphically represented in Fig. 4) such as may be'derived from a two-tube Kenotron rectifier,'or a continuous (non-pulsating) current such as may be derived from a static machine, mechanical rectifier with a suitable condenser, a high voltage generator, or the like.

In the arrangement shown in Fig. 3, the electrodes 40 and 43 are connected to each other by a conductor and by a conductor" to a suitable source of potential, here shown as a Kenotron rectifier designated generally by' the numeral 60. The electrodes 4| and 42 are connected to each other by a conductor 51 and to the ground by a conductor 58. With this arrangement the conductors 55 and 5-6 are preferably connected to the negative terminal of the Kenotron or other source of potential and its positive terminal may be grounded by means of conductor II. the ground and conductor 68, at which point the main circuit branches into two circuits, one of which comprises electrodes 42 and 43 and the conductor 55, the second branch circuit comprising the conductor 51 and electrodes 4| and 40. The conductor 58 connects the branch circuits to the negative terminal of the Kenotron and thus completes the main circuit from the Kenotron to the'electrodes.

This arrangement is particularly suitable for use when both sides of the sheet S are to be coated as it will be noted that the negativ or projecting electrodes 40 and 43 are on opposite sides of the sheet S and the intensity of the electrostatic fields established between each pair of electrodes is always the same. When this arrangement is used in conjunction with the apparatus shown in Figs. 1 and 2, the screens 52 and 53 may be connected to the electrodes 60 and 43, respectively, so that the particles discharged into the electrostatic field are first given a negative charge. The hoppers 50 and 5| and the screens '52 and 53 are preferably positioned so that the charged particles are delivered into that portion of the electrostatic field between the projecting electrode and the adjacent surface of the sheet to be coated.

In using the apparatus shown in Figs. 1 and 2 to carry out the process, the sheet material S,

such as a piece of fabric (Fig. 5), is drawn from the supply roll l8, through the bath 23 where a coating H (Fig. 6) of adhesive such as glue, paraflin, rubber cement, wax or the like is applied to both surfaces. While the adhesive coating is still tacky the sheet is guided between each pair of electrodes, as indicated in Figs. 1 to 3. The electrical connections are adjusted to produce the desired potential across the electrodes and thus establish an electrostatic field of the desired strength and intensity. After having made these adjustments the material to be applied is fed from the hoppers 50 and 5| at a predetermined rate and after passing through the screens 52 and 53 where the individual particles receive a negative charge, they are then carried by gravity into the electrostatic field. When material such as fiock, linters and the like fibers, as well as the various forms of abrasive material such as Carborundum, pumice, tripoli, etc., constitute the coating material being applied, the individual particles upon entering the electrostatic field, due to their elongate nature, become aligned in the direction of the electrostatic lines of force and are uniformly projected or bombarded against the adhesive surface of the sheet S so that their ends are deeply and firmly embedded in the adhesive coating at substantially the same angle and their projecting portions are disposed in substantial parallelism relative to each other. Due to the initial charge imparted to the particles, they tend to repel each other and become dispersed so that upon being projected against the adhesive surface of the sheet S the individual particles are spaced relatively to each other. As the individual particles align themselves with their major axes coinciding with the direction of the electrostatic lines of force, they may be applied to the sheet S so that their major axes are disposed at any desired angle relative to the surface of the sheet and consequently a greater number of particles per unit area may be applied to the sheet and with greater uniformity than is otherwise possible. When thus applied, their embedded ends are held in spaced relation to each other on the sheet S and by reason of capillary action and the removal of the iilm of air surrounding the particles the adhesive creep! up or rises along their sides forming a mensicus about the embedded ends of each individual P rticle.

After having received a coating of particles on one or both surfaces, sheet 8 is guided out of the deposition zone and passed between a pair of ultra-violet lights L and L' or other suitable means operative to discharge or neutralize the static charge carried by the coated surface without causing sparking. After removing the static charge on the sheet, it is then wound up on the reel I5. During both the coating and deposition operations the sheet 8 is held under slight tension bythe pull" of the winding drum and reel. The density of the coating may be varied, as desired, by varying either the rate of travel of the sheet 8, the rate of delivery of the particles from the hoppers 50 and BI, or both, and the stren th of the electrostatic field may be varied accordingly.

When applying fibrous material at a relatively low rate, a potential of the order of 15,000 to 25,000 volts may be used, although I prefer to use potentials from 100,000 to 500,000 volts, particularly where heavier particles are being applied or where the rate of application is to be greatly increased, the particular voltage depending upon the character of the particles, the rate of travel of the sheet, and various other operating conditions.

Figs. 7 to 10 show a form of deposition apparatus particularly suitable for the application of flock, linters, asbestos fiber. wood pulp fibers, fine abrasives and the like materials, to an adhesive coated surface of a base member. In the embodiment shown in Figs. 7 and 8 the sheet material S is drawn from the supply roll over a spreader roll 8| provided with a spreader blade 82 which is operative to distribute a fluid or plastic adhesive 83, such as rubber cement or the like, uniformly over the suriace of the sheet S. After having received a coating of adhesive of suitable thickness, the sheet is drawn over or about a guide member which constitutes a part of the deposition apparatus. Thereafter the sheet is drawn downwardly between a pair of discharging electrodes 84, 84 connected to a suitable sourceof high potential alternating current, then over a guide roll 86 and wound on a reel 81, as in the previously described apparatus.

The guide member preferably comprises a plate electrode interposed between two sheets of electrical non-conducting material such as Bakelite, the upper sheet or layer 80 having a smooth surface and being provided with a rounded or beveled edge as shown in Fig. '7. The negative electrode 90 is disposed opposite the end of the electrode 85 and is arranged so as to establish a field whose lines of force intersect the path of travel of the sheets at any desired angle. Preferably the length of each electrode is willcient to provide an electrostatic field having a width corresponding to that of the sheet S.

Asupply hopper 91 is disposed above the electrostatic field and is constructed and arranged to deliver the fibrous material onto a screen 92 or the like device interposed between the field and the hopper. -The electrical connections are shown schematically in Fig. 7 wherein a conductor 95 connects the screen 92 and the electrode 90 to the negative terminal of a suitable source of potential designated by the numeral 96, the positive terminal being grounded by a conductor 91 or connected to the electrode 85, as desired.

The electrode ll may be grounded by a conductor II or otherwise connected to the conductor 01, and suitable means such as a controller 99 and rheostat I may be provided to control the potential and flow of current in the circuit. If desired, a voltmeter IOI may be connected in the circuit in the usual manner. The electrodes 04, 00 when connected as shown in Fig. '7, establish an alternating electrostatic field across the path of the coated sheet and are thus eilective to discharge or neutralize any static charge carried by the sheet. The operation of the apparatus is substantially the same as that of the previously described apparatus, it being understood that the present arrangement is designed to coat only one surface of the sheet 8 at one time.

In the embodiment shown in Fig. 9, the cementitious material is applied to the sheet S in the same manner as in the embodiment shown in Figs. 7 and 8. In place of the guide member and plate electrode shown in Figs. 7 and 8, a roller electrode I is used. The roller electrode provides a guide roll about which the sheet S is drawn on its way to the winding drum or reel (not shown) and may be connected to the ground or otherwise, as in the previously described apparatus. The negative electrode I01 comprises a metallic screen member which is shaped to provide a substantially horizontal portion I08 through which the particles discharged from the hopper I 09 may pass, and a depending portion IIO disposed opposite but parallel to the roller electrode I05. The supply hopper I09 is disposed above the horizontal portion I 00 of the negative electrode so as to discharge the particles onto its horizontal portion. The negative electrode is connected to the negative terminal of the source of potential and the usual control devices may be provided as in the previously described apparatus.

The embodiment shown in Fig. 10 is somewhat similar to that shown in Figs. 7 and 9 but is particularly designed for use in applying particles to a sheet having an adhesive coating which comprises a thermoplastic cementitious material,

such as wax, parafiin, etc., which must be maintained in a relatively fluid or tacky condition during the deposition operation in order that the ends of the particles may be firmly embedded therein. The apparatus embodies all the essential elements shown in Figs. 7 to 9 but in place of the electrodes shown therein, a metallic block I I4 and rotor II5 are used. The block I I4 constitutes the positive electrode and preferably comprises a metallic casting having a series of longitudinally extending ducts or channels IIB which may be connected to a steam or hot water supply (not shown). The outer walls of the block I I 4 which contact with the sheet material are smooth'and the adjacent corner is preferably rounded or beveled to provide a suitable guiding surface over which the sheet S is drawn. The rotor II5 constitutes the negative or projecting electrode and preferably comprises a. cylindrical screen or grating supported on a circular plate which is rotatably mounted on a stationary tubular shaft Ill. The tubular shaft II! is provided with a radially disposed axially extending slot coextensive with the longitudinal extent of the screen and facing away from the electrode H4. A conduit II! having an elongate, horizontally extending, flaring mouth or entrance I disposed in radial alignment with the slot H8, is disposed closely adjacent to the electrode 5, as shown, and may be connected to a suitable suction fan or'the like (not shown).

' for discharging the static charge from the coated sheet may be employed. During the deposition operation the electrode II! is continuously rotated, compressed air being introduced into the shaft I I1 and discharged through the slot III, and the electrode H4 is maintained at a predetermined temperature by the fiow of steam or hot water through the ducts H0. The force of the air striking against the screen or grating of the electrode H5 is sumcient to remove any accumulations of oriented fibrous material or other particles and carry them into the conduit I20, thus keeping the negative or projecting electrode relatively free of oriented material.

Fig. 11 shows a coated sheet material produced in accordance with the present invention. The backing sheet consists of a sheet of heavy paper I28 and the fibers of the coating I21 are adhered thereto by a layer of adhesive I26 and are disposed at an angle of 45 to 60 relative to the backing sheet I28, thus presenting an appearance resembling suede.

The products are greatly superior to those made in accordance with the prior practices wherein the fibrous material is deposited on an adhesive surface of a, backing sheet by means of a current of air or by gravity. In such products the individual fibers are heterogeneously disposed on the surface of the adhesive and hence do not assume any definite position relative to each other. Consequently, such products do not possess the dense and uniform characteristics nor the attractive appearance or finish of those made in accordance with the present invention. Moreover, the wearing qualities of such products are greatly inferior to those made in accordance with the present invention due to the fact that the individual particles are not embedded to a sufilcient extent, if at all, in the, adhesive, and as the body portions and the ends of the individual fibers provide the surface of the product, the individual fibers are soon worn away or are easily dislodged from the adhesive and hence expose uncoated areas of the binder. In the products made in accordance with the present invention the individual fibers, being firmly embedded in the adhesive, are not easily dislodged and as their ends constitute the major portion of the surface of the product, they effectively resist wearing. Furthermore, due to the fact that a much denser coating may be applied to the adhesive surface of the backing sheet, there is a greater number of fibers per unit area to resist wearing and abrasion, and consequently the product of this invention will outwear those made in accordance with the prior practices.

While different desirable embodiments of the present invention have been shown, it is to be understood that this disclosure is for the purpose of illustration only and that various changes and modifications may be made without departing from the spirit and scope of the invention as set forth in the appended claims..

Certain phases of the invention are disclosed and claimed in the co-pending application Serial No. 375,432, filed January 22, 1941, which issued to Patent No. 2,287,837 on June 30, 1942.

What is claimed is:

1. The process of coating to provide a suedelike surface which includes as steps thereof feeding a carrier or backing and applying an adhesive layer to a surface thereof, and depositing on said adhesive layer particles of finely divided fibrous material under the influence of an electrical field whose lines of force are directed so as to orient the particles with their major axes at an angle of from about 45 to 60 with respect to the backing, attaching the ends of said particles to said adhesive layer and leaving the opposite ends free, thereby forming the suede-like surface for said carrier or backing.

2. The process of forming suede-like surfaces which includes as steps thereof feeding a carrier or backing and applying an adhesive layerto a surface thereof, and depositing on said adhesive layer particles of flock under the influence of an electrical field whose lines of force are directed so as to orient the 'particles with their major axes at an angle of from about 45 to 60 with respect to the backing, attaching the ends of said particles to said adhesive layer and leavin: the opposite ends free, thereby forming the suede-like surface for said carrier or backing.

GRANITE TRUST COMPANY, By IRVING L. SHAW,

Vice President, Executor of the Last Will and Testament of James S. Smyser, Deceased.

10 REFERENCES crrm The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 209,805 Goodall Nov. 12, 1878 1,194,874 Peterson Aug. 15, 1916 1,575,165 Hopkinson Mar. 2, 1926 1,710,747 Smith Apr. 30, 1929 1,788,600 Smyser Jan. 13, 1931 1,855,869 Pugh Apr. 26, 1932 1,886,234 Meissner Nov. 1, 1932 15 1,902,921 Underwood Mar. 28, 1933 27,3 7 Schacht Jan. 7, 1936 2,027,308 Schacht Jan. 7, 1936 2,047,525 'Ihode July 14, 1936 2,173,032 Wintermute Sept. 12, 1939 a 2,173,078 Heston S pt- 1939 FOREIGN PATENTS Number Country Date a 339,913 Great Britain Dec. 18, 1930 396,385 7 Great Britain AM. 1, 1933

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