US1662816A - Method of surface coating articles - Google Patents

Description

March 20,- 192s.

c. M. BIGELow METHOD OF SURFACE COATING ARTICLES Filed Dec. 8, 1924 ,as 'i Patented Mar. 26, .19218.

UNITED .STATES 'PATENT ifoFFijcE.

i chars n. naamw, or NEWTON, Massacnusnr'rs,

METHOD or sum-Aon coa'rnie Jin'rrcnns..4

Appliization led'De'cember lacquers, when feasible, in placeofvar-I '10 nishes and in producing uniformity of fthickness of coating or filming on 'anarticle or' surface, upon the first application 'of the material or compound thereto, thereby eliminatin the loss of time heretofore reJ quired to preparatory to `receiving subsequent "coats, in order to attain the proper thickness and uniformity thereof. f i It is a further object of the invention to '20, coat articles or surfacesin such manner as to entirely eliminate runs, thin places, .and

so called' fatty edges, and to produce a `film of substantially uniform thickness and at an g appreciablyreduced cost, particularly as to labor, and in less time per given article orlsurface than has been possible in the past. f

Primarily `this invention has ,for one of its objects encouragement in the use of lac- `quers for protective. coating in innumerabl'e ao instances where varnishes or similar compounds are now used and appliedatgreat cost of time, labor and materialand not always in a'satisfactory and durable manner.

It is also an object of this .inventionto suc- 85 cessfull'y and expeditiously coat articles having irregular surfaces or contours, which heretofore was not possible exceptingby the use of hand methods wherein highly skilled labor was necessarily employed, and conse- 40 quently present day requirements as t'o production andcostwere not attained. f

Another important object of the invention is to eliminate wastage of coating material during the application thereof, and to use` the vaporous gases arising from` the volatile coating material, or gases havingylike properties and derived .from other sources if need be, in carrying out a feature of theinvention. l l y,

In the drawing illustrating the preferred apparatus for practicing the present process,

Figure l is a vertical sectional view: of the apparatus; Fig. 2 is aside elevati/Qn of the right hand. .side of :the apparatus ry the article afterS each coating,

s`,1924. serial Nausea?. i

Fig.`1;and Fig. .3 is a cross-section on the line 3 3 of Fig. 1.

.A In pract1ce,the preferred method of covy ering an article with lacquer, for instance,

" :is bydipping it into the compound and al vowing it to 4drain 4thereinto, but it will be understood that in sofar as this invention is ;.concerned, it is immaterial how the coating is applied, whether by dipping, brushing, or VV:SPm-lll f 4 i i It wi l. be further understood that -while `this"`in've'i1tion is intended to be used in coni n ection withy lacquers, its use is not to be limitedthereto' as it might be used in connection lwith paints and varnishesor other materials which may be adaptable to its use.

. In carrying out the invention it is preferred to dip) the article in aftankcontain- 'ing lacquer, y mechanical means, and while the article is. in the lacquer impart motion to it, the mechanical means to be'employed and` the motion to be imparted depending 'upon fthe article to be coated.

I't has been the practice in the past to dip articles into varnish and the4 like and withdraw them into the surrounding atmosphere where-they were permitted to drain into the dipping tank during which process coagula-x tion or settin took place slowl i when varnish. was'- vuse and rapidly w en lacquers were used.

, This method did not include movement of` the article durin the drying processA and consequently a umform'thickness of coating was not obtained as runs occurred, thin places were evident, and the formation of vthin andfatty edges was therule.

. -In the'present instance, and preferablyby the use-o mechanical means, the motion iin-V parted totheA -article-during the dipping i thereof is continued when the article is withdrawn from the dipping tank, and is to be such-'a motion as to' preventruns and thin places, and to prevent excessive 4iiows in any particular direction andV to cause a uniformi'ty of coating to gradually take place after the excess material surrounding the -freshly di ped article has fallen away or dripped -t erefrom regardless of the conytinuedmotion of the aticle. slt is-a'fact that the speed of withdrawal of the article from the tank of coating or -`ilining material to eat extent determines yshown inf the final thickness o the filmk on' an article or surface, inasmuch as an article which has been slowly withdrawn from the tank will have appreciably less material adhering 4thereto than thesame article would have 1f withdrawn from the tank speedily.

In`view of the above it is considered a feature of this invention to control, to a considerable extent, the inal film thickness of an article by the speed or lack of speed of itswithdrawal froml the filming material.

' As is well known, lacquers dry very rapl] idly, and even when the freshly dipped article is kept in motion as above referred to,l

after having been dipped. in lacquer, is suspended or maintained in an area or zdne of vaporous gases which arise froml the lacquer tank, or the vaporous gasesI formed by the evaporation of lacquer or any of the known tliinners or solventsv of lacquer, for even an a extended period of time, surface evaporation is veryv appreciably retarded, which action conveniently serves a very useful adjunct to the present invention by permitting a natural and unretarded diffusion of the sol.

vent below the surface of the coating'.

It has also been discovered that by simple mechanical means, not deemed necessary to show herein, such as an air excluding cover I placed on the lacquer tank, it was possible to retain, confine and concentrate the vaporous gas arising from thelacquer, and; put 1t to use as a moisteningor film surface evapora- Ition retarding agent for lacquer on an arti cle suspended in its zone during the automatic place finding of the said lacquer.

. until the upper limit of the `is reached, where-it is nil. i

Advantage has been taken of this condi-- Yaporous gases are heavier than air and consequently seek a lower level, and 4when confined as just described, its 'density and moistening power areY greatest adjacent ythe surface of the lacquer in the tank, gradually decreasing in moistening power and density gaszone or areation to the end that the fumes or vaporous gases given off `by the lacquerin the tank have been confined and in some instances concentrated and put to valuable use in venient form of clamp surface of the lacquer in the tank to zero at a Y apparatus for practicing the present process,

10 represents a tank or chamber provided withscoveijs 12, 13v hinged and adapted to be opened up to a vertical position between successive operations of the present process, it being understood that the present process operates as' a batch or intermittent process. The lower portion of thetank 10 comprises a dipping tank and into which a plurality 'of articles ierein shown as saw handles are `dip ed during the operation of theprocess, asvill be described, to cover the articles with a coating material.` As herein shown, a plurality of they saw handles'are supported y holding devices 15 comprising any con- A and the latter are mounted to rotate with a shaft 16 journalled in bearings 17 slidable vertically in guide- Ways 18 mounted upon the sides of the tank. V,Provision is made for iotating'the shaft 16, and as herein shown the shaftlG is pro- -videdwith a sprocket 20 which is adapted to mesh with the links of an endless chain 22 passing over a lower sprocket 23 'and'an upper sprocket 24. The lower sprocket 23 is driven from a suitable source lof power through the driving pulley 25 and counter shaft 26, its rotation being controlled by a manually operated'clutcli indicated at 27 and providedwith an operating lever 28.

In practicing the present process the saw 'handles -or other articles to be coated are first dip ed into a bath of coating material by rotating the shaft 16 when the latter is` in a position such yas is illustrated in Fig. 1,'.

closed operating chamber above the level of the liquid coatingbath and within which chamber the vapors of the volatile solvent or solvents ofthe coating material are present due to the evaporation fronitne liquid coating bath and also from the articles being coated. The solvents, as is wellknown, are heavier than air, and consequently the density -or concentration of the solvent in .the

vapor space above the coating bath gradually decreases from the coating bath toward the top of the tank, and in practicing theV present process provi sion is made for slowly Irotating the dipped saw handles or other articles at successive stations or heights above the coating bath t'o `permit the coating material upon thel saw .handles orother articles to dry'i'n contact -With successive portions of the atmosphere :Within the tank containing gradually decreasing proportions of the volatile solvents. In this manner the rate of dryingof the coating material is controlled ,lso as to enablethe rotary movement of the articles at the successive stations to distributethe coating material u pon thev articles into a uniform lilm extending over all parts of the article.

. lAs herein shown, provision is made for manually raising the shaft 16 into they successive stations illustrated in dotted line positions in Fig. 1, While enabling theshaft to be rotated at each station.' For this purpose v the bearing blocks 17 are as above stated mounted to slide, in vertical guideways I18 and are connected by suitable cords 3Q to a Windlass 32, thereby permitting the bearing blocks 17'to be raised as the Wi'Idlass is. Wound up. Provision is made for holding the bearing blocks 17 at the different stations, and for this purpose holding dogs 34 'are provided and which are pivoted in levers 35 connected by a link 36, and which holding dogs 34 are yieldinfgl held -into a position to engage the bottom o the block 17, as the latter is raised past the particular dog, by a spring 38. When it is desired to lovverthe shaft when a fresh supply of saw handles or other articlesiare to be coated, the link 36J is depressed, throwing out the holding dogs 34 from the path of the block 17.

It Will therefore be seen that in the present process the article is first dip'pe in the liquid coating material and then dried While being rotated in contact with an atmosphere containing progressively decreasing proportions of the volatile solvent. After having been dried or substantially dried, thetank is opened by lifting the covers andthe article removed, and at thelsame time .opportunity 1s afforded for the vapors containing the solventto escape, thus permitting a fresli supply of air to be introduced into the chamvber or tank to dry the succeeding batches of v saw handles or other articles.

The present process is particularly' designed for producing anabsolutel unifornr film or coating lupon irregular s aped obto Va steady and. approximately constant sie .a

.found somewhere'intermediate the extremes thereof and readily located by easily performed experiments and might be observed through glass forming part of the tank cover,

Vhen`operating under this condition the i article is allowed to remain in the chosen positon untilthe lacquer thereon has found its place and uniformity of thickness thereof has been' attained, whereupon it is` Withdrawn from the vapor and exposed to the atmosphere Where lit rapidly congeals or sets providing this action has not beenaccom- -plished during its exposure to the vapor.

The invention contemplates the applicaion of protective coating of any kind that sol is adaptable to this method, and in any way best suited'for the occasion, ,or desires, and subjecting the article to movement 4of some sort, Whether it be rotary, vibratory or reciprocatry, best suited/to accomplish the results required and subjecting-the coated moving article to vaporous'gases, which method may be modified by omitting the movement of the article during the process, as in many classes of Work it might be prohibitive and even unnecessary. 1

The invention also contemplates the application of coating material in any suitable manner andthe movement of the article during the drying process and omitting the exposure to vaporous gases,. which in most instances may not be successfully dispensed with, but in othersmay not be required to ac eomplish .the desired result.

It Will be understood that, as previously referred to, Lthe invention might be used vin connection with paints and varnishes, or other materials which may be adaptedto lts use itis of especial importance in the rubber industry, particularlyin .the manufacture of thin rubber goods/or hollow articles such vas gloves, nipples, bathing caps, and in fact rubber goods of all kinds made up by dipping orV repeated dipping in a rubber 'or rub-- ber substitute solution, whether made on a form or core, or as a permanent coating to an article. l e Having described the invention I claim:

1.- The process ofsurface-'coating articles4 'with a. liquid coating material,containing a' volatile solvent which consists in dipping the article into a bath ofthe liquid coatingI material contained in the bottom of a chamber, closed during .thecoating operation, lifting the article fro'mthe bath andslowly rotatin vit at' a plurality of stations spaced succee ian ing .distances fromv the bath wherebyfthe slowly 'rotating article'is permitted to dryf 12 while being rotated -in contactv with latinos,- phere containing progressively decreamng proportions of they solvent, and thereafterk opening the receptacle to remove the article,

v 2.5,An intermittent 'process of surface-coatmg articles'witha liquid. coating f containing a volatile solventwhich'consists portions of the solvent, and then 'opening in dipping the article into a bath of the 1iqtile tank and removing the, dried coated aruid coating material containedin the bttlcle.. v

tom of a chamber, closed during thecoating Signed by meat Boston, Mass., this 4th 5 operation, and then removing the article and day of Dec., 1924.

rotating it until subst'antiall dry, inc0ntact with vapor 'containing ecreasing prov CABLE M. BIGELOW.

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