US2236397A - Method of drying finishes - Google Patents

Description

March 25, 1941. F. E. DRuMMoND METHOD 0F DRYING FINISHES rled'Aprn 17. 1959 1NvENToR.

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March 25, 1941. F. EDRUMMOND 2,236,397

METHOD 0F DRYING FINISHES Filed April 17, 1939 2 Sheets-Sheet 2 f Z iz-Lf f ,l l, 27 n zy/ n /q l if,

OXYGEN` OR ENRICHED RIR OXYGEN OR ENRICHED FUR W|TH OXIDATION CATALYST l FAN [IUUU [IU'UU uuuuuu HEATING ELEMENT INVENTOR.

Bywwm/ ATTORNEYS Prasad Mu. 2s, 194i UNITED STATES PATENT OFFICE l 2,236,391 'e Y Marnon or prima Fmsnas renom a; Drummond, Damn, ohio, miglior, by mesnc'asaignmentl, to New Wrinkle, Inc.,- Wilmington, Del., a corporation of Delaware Application Api-ii 17, 1939, serial No. assen s claim. (or 34-24) e My invention relates to a method for drying" coating compositions, and more particularly to the method of Iproducing wrinkle finishes.. The invention, however, is adapted for accelerating the drying of various types of coating compositions whi'ch dry to a hard flexible lm by oxidation, polymerization, evaporation of solvents or a combination of these actions.

It `is one object of this invention to produce wrinkle finishes comprising conventional nonwrinkling oil vehicles such asv linseed, perilla, soya bean oil, poppy seed, ish oils andthe like, which oils ordinarily dry to a smooth, glossy, non-wrinkling film.

Another object is to provide a method for producing articles having wrinkle iinishes from compositions comprising blends of non-wrinkling and wrinkling oils, which wrinkling oils include Chinawood, oiticica, and poyok in blown, .unblown` or 0 raw state.

Another object is to provide an Vimproved method of drying coated'compositions of the drying oil or oleoresinous type which ordinarily dry toa smooth surface so that they will dry to a wrinkle inish.

Another object is to provide an improved method of accelerating the surface drying of coating compositions in order to produce a wrinkle or irregular surface film.

Another: object oi' this invention is to provide a controllable atmosphere for baking coated articles to cause the coating-to'dry to a hard, smooth finish or irregular wrinkle surface as desired.

Another object is to provide an enclosure for force air drying coated articles by means of oxygenr orA ozone enriched heated air which also carries small amounts of an oxidation promoting catalyst for 'increasing the oxidation activity on the lm surface so as to produce a wrinkle finish.

Another object is to provide an improved method of accelerating the oxidation and polymerization of coating compositions applied toarticles in' a thin iilm soV as to lessen the time for dry' ing coating illms to a dust-fre'e-nish.

In general the wrinkling of coated lms is brought 'about by unequal "drying of the film producing surface volume changes which develop'- introvertedfolds in the surface skin ofthe filmi producingi' a' wrinkle finish. In the case-of dry- I ing oil coating 'films comprising wrinkling oils; for 'example'ichina-wood or oiticica, it has been found-that v4'folds or wrinkling of the illm surface may be brought about by excess oxidation and polymerization `at the surface of the lm. This invention provides an improved method of effecting this to produce a wrinkle coating on articles. Y Y v In the accompanying drawings:

Figure l is avertical sectional view of anarticle having a smooth surface coating;

Figure 2 is a vertical sectional view through an oven-showing the manner of exposing the material to heat and ultra-violet ray lamps for drying coated articles;

Figure 3 is a similar sectional view illustrating the arrangement for baking nishes which arey applied to both sides of panels or sheets;

Figure 4 is a similar view in section taken through a circular oven having heat and ultraviolet ray lamps mounted around the interior wall to concentrate the heat and light on irregular shaped articles which are to be dried to a wrinkle finish;

Figure 5 isa similar view of an oven as in Figure 1, illustrating the utilization of heat lampsvalone with means for admitting oxygen to enrich the atmosphere in contact with the coated article;

Figure. 6`is an elevation view, partly in section, of an oven showing the arrangement for admitting heated air which has been enriched with oxygen and having an oxidation catalyst incorporated therewith for drying' coated articles to produce a wrinkle nish.

Referring to the drawings in detail, Figure l shows a panel or article A having a smooth surface coating B. In Figures 2, 3 and 4 an Aoven generally designated I0 is illustrated for drying coated articles, according to my invention, to accelerate-the drying of the coating to a hard smooth illm or wrinkle surface-finish.

'I'he ovens are constructed in the forml of tunnels or rectangular enclosures having suitable means for lsupporting and lconveying coated articles into and out of the drying oven. Heat is supplied by banks of reflector equipped incandescent lamps i I which are arranged within the enclosure so -as to concentrate the rays onto 4 the surface of the coated articles. Preferably laments are used for this purpose.

Interposed between the heat lamps il are u1- tra-violet irradiating means I2. Any suitable source of ultra-violet ray producing -means can be employed, the quartz mercury arc. lamp of the Cooper-Hewitt type being readily applicable. Ultraviolet irradiation from a carbon arc may also be used if desired. 'I'he heat lamps and Ainfra-red radiating electric lamps having carbon ultra-violet lamps maybe arranged in alternate relatio` ship so as to provide even distribution of hea and ultra-violet irradiation of the atmosphere adjacent the articles being dried. In general the lamps should be placed between ten and thirty inches from the coated article. The light drying venclosures are not hermetically sealed so as to permit the ready exit of products of oxidation during drying of, the coated articles.

In the modification illustrated in Figure 4 the oven l! is of circular construction and the heat and ultra-violet lamps are maintained in spaced relationship around the walls so as to effectively direct the rays against all sides of an irregular shaped article. The lamps may, if desired, be

made adjustable so that their position can be changed relative to each other. It will also be understood that the number of heat lamps or ultra-violet lamps may be varied as required to increase or decrease the temperature of the enclosure and the ultra-violet irradiation of the atmosphere.

Ultra-violet irradiation provides means for ionizing the air in contact with the coating film forming ozone which accelerates the surface drying by auto-oxidation. This oxidation of the coating is enhanced by the heat lamps resulting in rapid surface drying of the film which expands laterally due to the oxidation and increased volume to produce folds or creases over the entire llm surface. By this method of accelerating the surface drying rate of films, coating compositions particularly of the drying oil type, which under the ordinary drying and baking temperatures do not produce a wrinkle finish, are made to dry to a satisfactory wrinkle finish. Heretofore in the compounding of wrinkle finishes, the use of substantial amountsof tung oil, oiticica oil or synthetic wrinkle resins of the drying oil acid modiiled type has been required for the production of wrinkle finish coating compositions. By the improved method of accelerating the surface drying rate of coating compositions according to this invention, the use of large amounts of these expensive drying oils is unnecessary and in general may be substituted by linseed oil, soya bean oil and the like non-wrinkling oils.

In Figure 5 the baking oven I4 comprises an endless conveyor l5 which is arranged for conveniently moving the coated articles into and out of the light drying enclosure. In this instance ultra-violet lamps are omitted and the heat lamps Il alone used. Oxygen or ozone enriched air is introduced into the drying oven as at I6; Where drying oil compositions used in coating the articles comprise raw China wood oil or similar drying oils which have not been heat .treated to a suiliciently high temperature to eliminate crystallization or gaschecking, the nitrogen dioxide content of the atmosphere may be maintained above 4 to 5 parts per million parts of air which brings about crystallization or gas checking of the nlm. Ordinarily, however, gas checking will not be produced even with articles coated with raw drying oils due to the comparatively short period of time between the evaporation of the solvents and the beginning of oxidation.

The usual drying oil coating compositions comprise metallic oxidation catalysts such as cobalt, manganese, lead in the form of linoleate or acetate, alone or mixtures of these. 'I'hese driers enhance the wrinkling and materially speed up the drying yof the lm especially when dried by the use of heat lamps as in'this invention.V T0

accentuate surface oxidation atomized organic solutions of metallic driers such as cobalt or manganese in the form of oleates, stearates. naphthenates. etc. may be introduced into the drying ovens to form a part of the atmosphere in contact with the coating illm. Metal driers colloidally dispersed in an oil soluble solvent such as butyl alcohol or petroleum spirits may be utilized.

This modification is illustrated in Figure 6 wherein the required temperature in the oven I1 for baking the coated articles is maintained by the introduction of preheated air, as shown. into which has been introduced oxygen or ozone enriched air together with an oxidation catalyst. It will be understood that heat lamps may be employed together with the circulating heated air .for maintaining the temperature in the baking oven I1 if desired. A fan generally designated I8 may be employed for forcing the circulation of air through the heating element I9 and circulating it through the oven, as shown in Figure 6.

The oxidation catalyst which may be introduced into the oven may comprise atomized organic peroxide such as acetyl or phthalyl or benzoyl peroxide dissolved in benzol or toluol. This solution may be suitably sprayed into the oven chamber or carried into the oven by the oxygen or stream of air being conducted into the oven. In this manner sufficient amount of oxidation catalyst can be placed in contact with the surface of the coating lm on the articles to accelerate the surface oxidation and drying of the coating to produce a satisfactory wrinkle finish. This will be enhanced further by the use of coating compositions comprising metallic driers. Clear varnishes as well as pigmented enamels may be dried to a wrinkle finish.

'Ihe usual temperatures employed in producing wrinkle finishes on metal surfaces are of the order of 150 up to approximately 450 degrees F. For producingwrinkle finishes on Wood, paper and similar materials somewhat lower temperatures, such as to 150 degrees F. may berused. The elevated temperatures produce a more rapid oxidation of the film surface and promote the production of wrinkle finishes and in general accentuate the wrinkle. Lower temperatures of baking 4usually require higher percentages of drying oils having poly-conjugated double bond structure in order to suilciently accelerate the oxidation rate of the film surface during the treatment to produce a wrinkle or irregular surface finish.

As an alternative manner of contacting the surface of the coating nlm with the oxidation catalyst, a thin lm of .the solution carrying the catalyst may be lightly sprayed over the coating just prior to introducing the coated articles into the baking oven. Further in place of the oxidation catalyst mentioned, oxidized turpentine which is high in active peroxide of oxygen may be utilized with or without the addition of metallic drier.

It will be understood that I desire to comprehend within my invention such modifications as come within the scope of the claims and the invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

l. The method of producing a wrinkle finish comprising drying oxidizable coating compositions in the form of a nlm including the steps of heating air, introducing oxygen in said air to increase the oxygen content above that normally assess? s present in ordinary airkadmixing an oxidation catalyst into said air and subjecting the coating film to said air into which the oxygen and catalyst have been introduced. 2. The method of producingwrinkle iinishes comprising drying oxidizable compositions in the formvof a fllm comprising the steps of concentrating infra-red heat rays onto said lm. heating air and Csimultaneously introducing oxygen' thereinto to increase the oxygen content above that normally present in ordinaryair, and subjecting the coating film to said air into which Voxygen has been introduced to eilect drying 'of the coating to a wrinkled surface.

3. The method lof producing wrinkle finishes from oxidizable paints, varnishes. and resinous compositions which comprises the steps of focusing heat rays on to the, iilm surface. heating air.-

incorporating oxygen in said air,to increase the oxygen content above that normally present in air, concurrently addingoxidation lcatalyst into ,said heated air and 'subjecting thecoated articles thereto to produce a wrinkled surface coating.

4. The method'of producing at wrinkle nnish from coating compositions comprising non-wrinkling oils consisting of dryingl the coating in the form of a nlm andaccelerating the surface drying ofthe nlm by heating'the air in which the' 3 coating iilm is to be dried, introducing oxygen into said air to increase the oxygen content of the .heated air above that vnormally present in ordinary air, and spraying the coating iilni with an oxidation catalyst immediately prior to drying said illm toeii'ect accelerated oxidation and drying of -theiilm at its-surface whereby an irregular wrinkled surface isfgproduced.'1

5. The method of producing a wrinkle nish oy treating an varticle having a illm of the coating composition thereon, comprising sprayinga light coating of a solution containing an oxidation catalyst over said coating lm Just' prior to drying said coating nlm, subjecting the film to heated air, introducing oxygenpinto said air and drying the coating lmin said heated air to produce folds or creases in the surface of the tllm and n form an irregular wrinlgled finish.

6. A method of Lproducing 'a wrinkle nish by accelerating the surface drying of the composition in theform of a-illm comprising the steps of concentrating infra red'heat rays onto the l' surface of the ilim and simultaneously subjecting said nlm to air in which oxygen contenthas been substandaliyincreased above that normally 2 a constituent part of air. Y

' Folsom E. DaUsmoNn.

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