US2438135A - Method of handling coated articles during drying - Google Patents

Description

M. D. SWARTZ ET AL March 23, 1948.

METHOD OF HANDLING COATED ARTICLES DURING DRYING Filed March 26, 1942 Patented 23, 1948 METHOD OF HANDLING COATED ARTICLES DURING DRYING Milton D. Swartz, Baltimore, and Kinloch N. Yellott, Cockeysville, Md.. assignors to Farboil Paint Company. Inc., Baltimore, Md., a corpo ration of Maryland Application March 26, 1942, Serial No. 436,344 2 Claims. (01. 117-403) 1 The present invention relates to the coating of articles adapted to travel at relatively high speeds. More specifically, th present invention relates to the manufacture of insulated electrical conductors, tapes, gimps, cords, and the like, said articles being provided with a finishing coat.

In the production of articles of the character set forth and similar articles, the final coating composition is applied while the article is traveling through a coating apparatus at a relatively high speed, said coating apparatus including in its usual form a sheave or wheel member over which the article is guided.

One of the difficulties involved in the coating of the article is the picking up or collection of particles of the coating composition, as for example, the paint or lacquer, on the sheaves or guide wheels if, for any reason, the coating com-- position is not thoroughly dry when the article being coated touches the sheave during the coating operation. When this condition is encountered, and small particles of the coating composi tion adhere to the sheave or guide wheel, these particles, as the sheave revolves, pick up or collect more and more of the coating in a manner similar to a snowball rolling down a hill, with the result that progressively larger portions of the coating composition are irregularly removed from the articles being coated, the article is damaged in appearance, and its utility lessened.

It has been discovered that this condition can be eliminated and that a coated article free from so-caused irregularities can be produced provided the contact surface of the sheave is coated with a composition adapted to prevent the picking up of particles of the finishing coating as the article passes over the sheave during the finishing operation.

In order that the present invention may be clearly understood, reference will be made to the following drawing, in which:

Figure 1 is a plan view of a jacketed electrical conductor;

Figure 2 is a prospective elevation of a suitable coating and drying device for coating the electrical conductor;

Figure 3 is a cross sectional view of an applicator pot taken'on line 3- -3 of Fig. 2;

Figure 4 is a side view partly in section showing means for applying the dressing to the sheave member.

Figure 5 is a side view of the apparatus shown in Fig. 4; and I Figure 6 is a detail of the wiping gasket.

The coating and drying apparatus shown in the drawing comprises an applicator pot l sultably located in a tower M, said applicator pot being provided with a partition 2 whereby there is formed a compartment 3 adapted to contain a color coating composition 5, and a Wax coating compartment adapted to contain a waxing material 6. Suitable upper and lower rolls 1 and 8 are provided, the wire which is to be color coated passing from the pay-ofi reel it] under guide roll II and through the coating composition 5 contained in the applicator compartment 3. The wire 9 passes through the coating composition 5, through the wiping gasket I2, around the upper roll I, then back down and around the lower roll 8, then through the coating composition 5 a second time, and, if necessary, through the coating composition a third time. Thereafter, the coated and dried wire passes through the waxing compartment 4 and then to the rewind reel I3. The tower M is preferably, although not necessarily, an air conditioned chamber; that is, the chamber may be controlled from the standpoint of temperature and from the standpoint of humidity.

There is rovided immediately below the sheave 1 a vessel l5 having a series of rotating wheels ll, said vessel containing a dressing medium l6 of the character hereinafter more fully set forth.

The rotating wheels I! pick up the dressing medium in the vessel l5 and apply it, preferably in a continuous thin film, to the guide grooves la during the coating process. The rotating wheels I! may be driven by a suitable mechanism, or

caused to rotate by frictional contact with the sheave roll 1.

Referring to Fig. 1, there is diagrammatically set forth an electrical conductor which may be provided with a final finishing coat. In Fig. 1, the metal conductor is identified by the letter A. This metal conductor may be copper or any equivalent material. The conductor may carry a sheathing B which is preferably rubber or other equivalent material, over which there is braided, woven, knitted or wound a fibrous jacket C which is coated or impregnated with a saturating compound D,-which may be asphalt or equivalent materials. To the so-treated wire there is usually applied an intermediate coating E which may be stearine pitch or the equivalent thereof. It is quite customary to cover the coating E with a color coating or finishing composition F. It is this final color coating or finishing composition which is applied by the method herein set forth and to which the present invention is primarily 3 directed so that the picking up of particles of said finishing coat as the article passes over the sheave during the finishing operation is substantially prevented or inhibited.

In carrying out the coating process, it has always been desirable that the wire 9 become dried during the period of its travel from the applicator pot I to the top sheave or roll 1. Further, height of the tower M and the rate of dry of the coating composition determine the time of this period of travel which is necessary and therefore limit the speed at which the wire can travel. In commercial practice, the wire travels at a maximum speed compatible with operating conditions. If the finishing coat which has been applied to the insulated wire is not dry by the time it touches the top roll 1, then the coating will be marred or portions of the coating will be removed by the sheave as hereinbefore set forth. Previous to the present invention, despite the precautions that have been taken to have the correct period of travel, in many cases a substantial amount of wire was so disfigured because of the failure to properly dry that the wire was not commercially salable. This marred or disfigured wire had to be again carried through the-coating process.

It has been discovered that marring or disfiguration of the final finishing coating applied to the wire or other article being coated can be totally eliminated or greatly inhibited by applying to the sheave over which the article is being guided a dressing medium which functions to prevent the removal of small quantities of the coating composition from the article being coated, and the picking up of the removed particles by the sheave wheel or roll over which the article that is being coated passes.

It has also been discovered that using a finishing composition having a given rate of drying in a particular tower in which the wire is being processed, the rate of travel of the wire through the tower per unit of time may be increased from what has hitherto been thought to be a' maximum under a given set of operating conditions, and this increase in speed can be effected without the production of marred or disfigured wire. For example, in processing an electrical conductor such as shown in Fig. l, the final finished coating is applied and the conductor is dried while traveling at a speed of 125 feet per minute, and under such conditions there is a minimum of unsalable wire produced. However, utilizing the present invention whereby the sheave surface, which may be a metallic surface such as hardened steel or equivalent materials, or a vitreous enamel surface including porcelain enamel, has applied thereto the herein disclosed dressing, the speed of travel of the electrical conductor to which there has been applied the same final coating composition may be increased to at least 200 feet per minute, and, further, the speed of travel of the electrical conductor through the tower may be increased to as much as 600 feet per minute provided the coating and drying apparatus is suitably adjusted. Similarly, if the electrical conductor is coated by the usual process utilizing the usual predetermined finishing coating composition, said conductor may travel at a normal, predetermined rate of speed which may be about 300 feet per minute, and there will be a minimum amount of wire which is marred or disfigured. The present invention enables an increase in production without plant expansion because the speed of travel of the conductor through the tower utilizing the identically same final finishing composition may be increased from about 300 feet per minute to 600 feet per minute, and the percentage of marred or disfigured wire will be greatly reduced over the amount of disfigured or marred wire produced at the lower speed of travel. In fact, when doubling the speed of travel, marring or disfiguring of the final finishing coating is substantially prevented. or inhibited.

It is further desired to point out that the present invention enables the use of finishing coating compositions which normally could not .be used in a given apparatus wherein the wire would normally travel at a given predetermined rate. For example, a given finishing composition prior to the present invention could not be used when the electrical conductor-was traveling at a rate of speed of 300 feet per minute because the coating composition, under the conditions of processing, would not dry sufficiently during the time of travel of the wire from the application pot to the upper sheave to prevent very substantial disfiguring or marring of the finishing composition. When the sheave has a dressing applied thereto, as herein set forth, this same coating composition may be utilized in the same tower to coat wire traveling at a rate of 300 feet per minute, and the wire will not be disfigured or marred. In other words, utilizing the present invention, the same coating composition may be used and the same speed of travel may be used in the same tower and there will be no disfigurement of the resultant Wire.

The finishing coating composition which is adapted to form the coating F shown in Fig. 1 of the drawing may be any of the prior art coating compositions including any of the well known cellulose lacquers, natural or synthetic gum or resin compositions, or ordinary paints and enamels. Compositions of this type are well known to those skilled in the art and the above are broadly set forth for the purpose of illustration and not by way of limitation. As an example of the so-called normal drying cellulose lacquer compositions, the following is set forth:

The following is an example of a finishing composition having as -its basic ingredient an alcohol soluble gum:

Table 2 Per cent Manila gum 24.0 Denatured alcohol 27.0 Castor oil 1;4 Metallic red oxide 32.0 Asbestine 1516 Following is an example of a composition based on a synthetic resin:

Table 3 Per cent Titanium pigment 49 Zinc nxirle 9 Tinting color 2 Castor oil 3 Alkyd resin 22 Mineral spir 5 Hydrogenated naphtha Suitable coating compositions may also be compounded as follows:

Table 4 Per cent Metallic red oxide 33.33 Filmscrap or cellulose nitrate 7.82 Shellac .78 Acetone 56.97 Methyl alcohol .94 Beta naphthol .16

Table 5 Per cent Chrome green 5.5 Yellow iron oxide 8.5 Titanium dioxide 3.6 Lamp black .93 Prussia blue .93

Filmscrap 8.8 Camphor .28 Shellac 3.42 Methyl alcohol 2.97 Beta naphthol .14 Acetone 64.98

Table 6 Per cent Metallic red oxide 27.5 Filmscrap or cellulose nitrate 8.7 Shellac 1.2 Acetone 61.03 Methyl alcohol 1.41 Beta naphthol .16

Table 7 Per cent American Whiting 9.65 Asbestine 5.60 Red iron oxide 15.30 Filmscrap 7.15 Alkyd res 3.28 Aluminum stearate 0.87 Beta naphthol 0.005 Hydrogenated petroleum fraction 7.95 Acetone 50.195

Table 8 Per cent Titanium dioxide 37.0 Ferric oxide yellow 1.88 Lead chromate 7.08 Red iron oxide 1.25 Filmscrap 5.16 Alkyd re 3.96 Maleic anhydride resin 2.475 Blown castor oil 1.88 Methyl acetate 33.40 Methyl alcohol 5.91 Beta naphthol 0.005

It is desired to point out that the cellulose compound may be film scrap, cellulose nitrate, cellulose acetate, ethyl cellulose, cellulose formate, cellulose propionate, cellulose butyrate, any of the higher fatty acid cellulose compounds, or any 6 of the cellulose materials commonly used in the manufacturing of lacquers.

Examples of natural gums or natural or synthetic resins which may be used as a basic binder constituent of the coating composition are pontianac, Manila gum, kauri, Congo, sandarac, shellac dammar, ester gum. rosin, lime hardened rosin, and the like. Among the synthetic resins which may be used as the basic binder constituent of the final coating composition adapted to form the coating F shown in Fig. 1 may be mentioned the phenol aldehyde condensation products, including phenol formaldehyde condensation products, furfural condensation resins, urea and thiourea aldehyde condensation products includin urea and thiourea formaldehyde products, alkyd resins including the glyptals, chlorinated rubber compounds including those known under the trade name of Pliofilm, synthetic rubber compositions, and the like. These coating compositions may, when necessary, have incorporated therein a plasticizing agent, as for example, esters of phosphoric acid or esters of phthalic acid. Any of the prior art plasticizing compositions may be used.

The basic requirement of the dressing medium is that it shall prevent the removal of small quantities of the coating composition from the article being coated and the adherence of the removed coating material to the sheaves. There are numerous known compositions which may be used and, therefore, broadly, protection is desired upon the .basic discovery of the desirability of applying to the sheaves a dressing material for the specific purpose set forth. It is desired to point out that it has been further ascertained that most lubricating mediums serve admirably as a dressing medium functioning to prevent the removal of particles of the coating medium from the article being coated and thesubsequent picking up of the removed particles by the sheave over which the article being coated passes. However, it is recognized that the present invention is not limited to the use of lubricating materials as the medium functioning to prevent the removal of the coating composition from the wire as it passes at relatively high speeds varying from to 800 feet per minute over the sheaves, and the subsequent picking up of the removed particles on the sheave.

The preferred dressing material should keep the coating composition, as for example, a paint, lacquer, size, or any other coating composition, from being removed from the article being coated and sticking to the sheave or other guide means. Further, when the dressing composition is of such a character that small quantities thereof adhere to the article as it passes over the dress sheave, the dressing material should not prevent adhesion between successively applied coats of the coating composition when it is necessary to apply several coats. Additionally, when several coats of the coating composition are necessary, the dressing material should not prevent the adequate drying of a given coat before another coat is successively applied or, stated differently, slow up the drying rate of successively applied coats of the coating composition. Further, the dressing used in carrying out the present invention should be of such a character that when admixed with a coating composition in such proportions which are carried from the sheave to the coating composition pot during the application of successive coats, the desirable properties of the coating composition will not be destroyed during the time the article iscoated, dried, and after the -ceat'ing composition sets to its final-state. More specifically, the dressing should have no efiect upon the adhesion properties of the coating composition and also preferably not affect its gloss. These are properties of the coating composition that are of importance when the article being coated is an electric conductor carrying acolor coating. When other articles are coated, the dressing material may be compounded so as to not'affect the predetermined desirable properties oi. the coating composition.

The following compositions are set forth as suitable dressing mediums. It is obvious that these are illustrative and not by way of limitation.

Table '9 Percent Tallow 12 Parafi'in 25 Solvent naphtha 21 Kerosene 2 Table 10 Per cent Lanolin 47 Solvent naphtha 14.5 Kerosene 38.5

Table 11 Percent Degras 23 Solvent na htha 21 Kerosene 56 Table 12 Per cent Light petroleum .oil. 62 Kerosene 38 Table 13- Per cent Linseed oil 71 Solvent nanhtha 29 Table 14 Per cent Soya bean oi 74 Low viscosity mineral oil 26 Table 15 Per cent Oiticica oil 64 Coal tar naphtha 36 Table 16 Per cent Carnauba .wax Candelila wax; a

Dipentine 91 Table 17 V Per cent Maleic anhydride resin 1'7 Hydrogenated naphtha 83 Table 18 Per cent Rosin potash soap 29 Solvent naphtha 71 Table 19 Percent Sodium palmitate '22 Water '78 Tablezll .Per cent Aluminumsteatate .21 Kerosene 79 Table 21 The compositions set forth in Tables 22 and '23 are solids at room temperature and. are preferably applied in .a liquid state to the groove 1a of the sheave .1 after the composition has been melted. The remaining examples are all liquid compositions at ordinary temperatures. While it is preferred that the exceedingly thin film of dressing which is applied to the groove la be liquid, it is not necessary that the film have a liquid consistency; it may have a solid consistency. It is desired to point out that the thinner the film of the dressing, the more satisfactory the results from the standpoint of the amount of dressing which is carried by the article being coated from the sheave to the applicator box, and from the standpoint of the amount of the dressing thrown off by the sheave-due to the centrifugal force developed bythe sheave rotating at a relatively high rate of speed, which rateof speed is, of course, increased as the rate of travel of the wire is increased, and by way of illustration, the speed of said sheave may vary between to 1000 revolutions per minute.

It is desired to point out that when the wire travels at a speed of 600 feet per minute, approximately three-fourths of a million feet of wire can-be coated in a 24-hour day in one machine, said wire being 'coated'with a composition set forth in Table 5 and the sheave being coated with a dressing composition set forth in Table 11. The resultant wire is entirely free of mar'and disfigura'tion caused by sticking of the final finishing coat on the sheave. This contrasts with the best previous results wherein 8 to 10% of the wire was usually inadequately coated and was rejected.

While the present invention has been illustrated by its application of a color coat to an electrical conductor, the'basic principles thereof may be applied to any article which is capable of being passed at a relatively high speed through a. coating apparatus, as for example, textile and/or paper filaments, threads, ribbons, cords, tapes, gimps, and the like.

The present-invention also may be used in the production'of tire tape. Ordinary tire tape is impregnatedon both sides with an asphaltic compound and-such tapemay have applied thereto on one sidea cellulosiccoating and the latter may be'dried whilethe tape is traveling through a tire at a speed varying between to 200 feet per minute oy 150th 1000feet per minute.

Ibis not necessary that the final finishing coatinghave a color component. This, in the manufactureof some articles, may be omitted.

Articles of the character herein set forth may be providecl'With-a final coating material which functionsitoimpartslippery characteristics to the artrcle. For example, "the. electrical conductor shown in Fig. 1 is provided with a wax or waxlike coating G.

Referring to the dressing material set forth in Tables 9 to 23, inclusive, it is to be noted that in a number of cases, the dressing material is prepared by dissolving a greasy component such as lanolin, degras, and tallow and/or paraflin, in a solvent or dispersion agent for these materials. The use of the solvent or dispersion agent facilitates the application of a uniform thin film of the dressing material to the sheave surface. However, it is not necessary that the solvent or dispersion agent be used as results can be obtained by using a solid dressing material. The use of the solvent or the dispersion agent simply represents the preferred and best mode of carrying out the invention, and it is not desired to be limited thereto.

While it has been indicated that light petroleum oil may be used as a constituent of the dressing medium, it is desired to point out that any of the petroleum oils normally used in the lubricating industry may be used and the viscosity thereof may be reduced as desired by the use of a diluting medium with which the petroleum oil is soluble or with which it is miscible.

Linseed oil is set forth in Table 13 as a constituent of the dressing material. Instead of linseed oil, any of the vegetable oils drying or semi-drying, or non-drying, may be used; as for example, Perilla oil, oiticica oil, olive oil, cotton seed oil, soya bean oil, peanut oil. The animal oils also may be used, as exemplified by whale oil or hydrogenated whale oil. The

vegetable and mineral fats function well as con-- stituents of the dressing composition. The vegetable and mineral oil waxes also give good results. The metal salts of the fatty acids such as aluminum stearate, calcium stearate, aluminum palmitate, sodium palmitate, also may be used in carrying out the present invention.

It is desired to state that it is not desired to be limited to any particular dressing composition, and that the protection which is desired is upon the broad and basic idea of applying a dressing composition to a sheave member, said dressing composition performing the functions hereinbefore set forth.

It is recognized that some of the dressing mediums herein set forth give better results than others. For example, the composition set forth in Table 12 is not so satisfactory as those set forth in Tables 9, 10 and 11 because when any appreciable quantity of petroleum oil is carried into the applicator pot during the coating process, it has a damaging effect on the rate of drying of the coating composition with which it then becomes mixed.

While the final finishing coating, typified by coating F, in the conductor set forth in Fig. 1, is applied by passing the conductor through an applicator pot, it is within the province of the present invention to apply the coating in other ways, as by spraying the final coating on the article.

It is desired to point out that the dressing material of the present invention functions to prevent adhesion between the surface of the newly applied coating and the contact surface of the guide means as the article passes over said contact surface during the coating step and before the coating composition has become thoroughly dried. It is desired to point out that the adherable film of dressing medium which is applied to the contact surface of the guide means 10 should satisfy one of two conditions: namely, (a) the cohesive force holding the particles of the dressing material together should be less than the cohesive force holding the particles of the newly applied coating composition together and said cohesive force holding the particles of the dressing material together should be less than the adhesive force holding the coating composition to the article being coated; (b) the adhesive force holding the dressing medium to the contact surface of the guide means should be less than the cohesive force holding the particles of the newly applied coating composition together and less than the adhesive force holding the coating composition to the article being coated. If condition (a) is satisfied, it is impossible for the partially dried film of coating material to be removed from the article being coated or to be partially removed from itself; that is, for a part of the coating film to be pulled away from the remainder of the coating film. By reason of the fact that the cohesive strength of the dressing material is lower than either of the other two forces, the dressing material would be split, a part of it adhering to the sheave and part to the coating composition, with the result that it would be impossible for any of the coating composition to be removed from the article being coated. If condition (1)). is satisfied, it is also impossible for any of the coating composition to'be removed since the adhesive force between the dressing material and the sheave is lower than the above-mentioned two forces, and any sticking between the dressingmaterial and the coating composition would result in the removal of the dressing material from the sheave. It is recognized that under normal operating conditions, there is al-' most always a tendency for the partially driedv coating composition to adhere to whatever surface it comes in contact with. The present invention provides a surface which will not allow the partially dried coating composition to stick to the guide means since the former does not come into direct contact with the guide means but only with the dressing material, which material is of such a character that it either pulls entirely free from the guide means orthe surface layer thereof is divided, part of it adhering to the guide means and part being takenoif by the article being coated. In either .case, there can be no removal of the coating composition from the article being coated.

The dressing material may be solid or liquid and of sufficient consistency to maintain a relatively thin film on the contact surface of the guide means. The dressing material should adhere to-the contact surface of the guide means;

that is, it should be capable, when applied to the contact surface, of initially adhering thereto. Thereafter, all or part of the dressing ma-- terial may be removed during the contact of the dressing material with the newly applied coating composition which has not completely dried before it comes in contact with the contact sur-.

face of the guide means. While, as stated, in

normal operations, the dressing medium does adhere or stick to the incompletely dried coat-.

ing composition, under the most favorable operating conditions, it is desired that this tendency of the dressing material to stick to the newly applied coating be substantially inhibited or reduced to a minimum. This is desirable because the less the amount of the dressing material which is carried by the newly applied coating,

arenas-s the less dressing material will be mixed witlr the ceating composition in the applicator box. In other-words. it is desirable; to reduce to a minimum the amount of dressing composition which is admixed: with the coating composition present in the applicator boxso that the predetermined characteristics of the coating composition shall not be; materially varied. and for the further reason. that this characteristic naturally determines the amount of the dressing materialwhich is consumed during a day's: operation. Further, it is highly desirable that the quantity of" dressing material. which. in normal operations, is unavoidably mixed with the coating composition in the-applicator box. shall not affect the drying rates-of successively applied coatings-or films or the adherence oii successively applied'coatings or films one to. the othen'and' to the article being coated. Most, if not substantially all of the adhering dressing is removed from: the surface of the initial coating film carried by the article. as. the latter passes through the applicator box. However; any suitable means may be provided toefiect. such removal of adhering dressing when the same becomes necessary. Such: removal means may be used where successive coats are sprayed on the article being coated. Additionaliy. the dressing medium employed should be relatively chemically inert toward the contact surface of the guide means.

It isrecognized that there are present in some of the dressing mediums herein set forth ingredients which. if carried into the coating composition contained in the coating composition: compartment in appreciable quantities. would damage the coating composition so that it would not form a suitable finishing coat. However, when such ingredients are present. the dressing composition must be of such a nature that'theamounts carried over to the coatingcomposition compartment areso small that the predetermined desirable properties of the coating composition and the resulting film deposited on the article being coated are not materially varied. As a usual rule. all that is necessary is that anexceedingly thin film of the dressingmaterial bemaintained on the contact surface of the guide means. The thinnest film that may be maintained'on' the contact surface of theguide meansis sufficient to carry out the present invention. Usually, a film of dressing materialvarying between lomi to atom of an inch is suflicient. bviously. the thickness of the film may be increased so that the film may vary fI'Om'MOODD of an inch to /3'4 ofan inch, or even more. Thesefigures are set forth by way of illustration and notbyway of limitation.

It is recognized that for different coating compositions, di-fferent dressing mediums may be necessary toobtain the preferred result, but the basic principle in all cases is the same; namely, that the cohesive force holding the particles of the dressing material together is less than thecoh-esive force holding the particles of the newly applied coating-composition together andthat the cohesive force holding the particles of the dressing material together is less than the adhesive force holding the coating composition to the article being coated; or the adhesive force holding the dressing medium to the contact surface of the guide means is less than the cohesiveforce holding the particles of the newly applied coating composition together, and less than the adhesive force holding the coating composition to the article being coated.

The guide members may furnish a contact surface of cast iron, low or high carbon steel, Monel metal, rustproof steel chromium alloys, copper, copper alloys, brass, bronze, vitreous enamel, ceramic materials, wood, or any of the prior art materials commonly used in the manufacture of guide members.

While kerosene, solvent naphtha, coal tar naphtha and water have been set forth as suitable solvents or dispersion mediums for the dressing base, such as degras, lanolin, tallow, and the like, it is obvious that these solvents are set forth by Way of illustration and not by way of limitation. The criterion for the solvent or dispersion medium is that it should be relatively inert toward the contact surface and toward the finishingcoating composition. Obviously the character of the solvent or dispersion medium will therefore, depend on the character of the coating composition. Having once set forth suitable examples, those skilled in the art will be able to compound for any particular purpose a dressing composition having a dressing base together with an appropriate solvent or dispersion medium.

In: some of. the examples, certain percentages of the solvent or dispersion medium are set forth, In Example 9, the solvent constitutes 63% of the composition; in Example 10, 53% of the composition; in Example 11, 77% of the composition; in Example. 12, 38% of the composition; in Example.13-, 29% of the composition; in Example 14, 26% of the composition; and in Example 15, 36% of the composition. Here, again, the percentage of solvent may be greatly varied from the proportions set forth which are by way of illustration and not by way of limitation.

From. the above, it may be gathered that protection is desired upon the basic principles of the invention herein set forth, and said invention is not tobe limited by the character of the dressing composition provided that said composition satisfied the criterion set forth.

While the present invention has been applied toa finishing coating, the principles thereof may be applied to any intermediate coating which passes over a contact surface which, in the absence of the dressing, functions to remove particles of the coating composition from the article, said particles also adhering to the contact surface.

There hasbeen provided, in accordance with the present invention, a method of preventing the removal of a newly applied incompletely dried coating composition from an article traveling at a high linear speed as the article carrying said composition passes over the contact surface of a guide means. The coating composition usually contains a covering constituent together with a solvent, said covering constituent including an agent for causing the coating composition to adhere to the article bein coated. When the article being coated is an electric conductor, a coloring constituent is present, but this is obviously optional as the invention is viewed from its broad standpoint. It is desired to emphasize the fact that the coating composition, as far as the present invention is concerned, is in the prior art and that there are a great many well known coating compositions which have the characteristic of sticking to the guide surface which may be applied to an article being coated. Therefore, the present invention is not limited to the specific coating compositions herein disclosed. In accordance with the present invention, there is maintained on the contact surface a film of a dressing material which substantially prevents the removal of small quantities of the partially dried coating material from the article being coated, said dressing material in one form of the invention being preferentially characterized by the property of avoiding any substantial sticking of the dressing material to the coating composition during the time the coating composition is in contact with the contact surface of the guide means.

In another form of the invention, the dressing material may stick to the coating composition in small quantities and be carried by the article being coated and dried for a portion of its travel in preference to being retained on the contact surface of the guide means and the dressing carried thereby. The dressing material in its preferred form when admixed with the coating composition should not deleteriously affect the properties of the coating composition, as hereinbefore pointed out.

Having thus described the invention, what we claim as new and desire to secure by Letters Patent is:

1. The method of treating an article carrying a newly applied coating having a volatile solvent component as the article passes in a coating and drying apparatus from application means to and around rotary guide means provided with a contact surface comprising passing the article through the apparatus at such a linear speed that the volatile component of the coating is incompletely evaporated and the coating is incompletely dried during the time the article travels from the application means to and around the rotary guide contact means, and inhibiting any substantial disfigurement of the undried coating by maintaining on the guide means a dressing medium selected from the group consisting of a 14 mineral oil base, a vegetable oil base, animal fats, and soaps thereof, said dressing medium being incapable when admixed with the coating composition of affecting the drying rate of the coating and of destroying the predetermined desirable properties of the coating composition during the time the article is coated and dried.

2. The method of treating an electrical conductor carrying a newly applied coating composition having a volatile solvent component as the electrical conductor passes in a coating and drying apparatus from application means to and around rotary guide means provided with a contact surface, comprising passing the electrical conductor through the apparatus at such a linear speed that the volatile component of the coating composition is incompletely evaporated and the coating is incompletely dried during the time the electrical conductor passes from the application means to and around the rotary guide means, and inhibiting any substantial disfigurement of the undried coating by maintaining a wool grease base on the guide means, said wool grease base being incapable when admixed with the coating composition of affecting the drying rate of the coating and of destroying the predetermined desirable properties of the coating composition during the time the electrical conductor is coated and dried.

MILTON D. SWARTZ. KINLOCH N. YELLOTT.

REFERENCES CITED UNITED STATES PATENTS Name Date Hinsky Mar, 26, 1940 Number

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