US2450681A - Apparatus for coating fiber insulation board - Google Patents

Description

c. s. MUENCH 2,450,681

APPARATUS FOR COATING FIBER INSULATION BOARD- Get. 5, 1948.

Filed Oct. 4, 1943 a Q72 (/2 y I M I .flffarvzeq Patented Oct. 5, 1948 APPARATUS FOR COATING FIBER INSULATION BOARD bar-l G. Muench: Glenview, 11]., assignor to The Celotex Corporation, Chicago, 111., a corporation of Delaware Application October 4, 1943, Serial No. 504,849

1 Claim. 1

. generally around 16 pounds per cu. ft. or a density of about .25. These fiber insulation boards are relatively soft and being composed of relatively coarse fibers their surfaces as they are produced are not smooth.

The inventions of this application relate in particular to the application of a finishing coating applied to the surface of a fiber insulation board as above mentioned, which surface coating is in the nature of a paint coat or finish and which provides a substantially smooth finished surface which may be colored substantially as desired.

Very briefly the inventions hereof involve the application of a coating to a surface of a fiber insulation board followed by the drying of the coating and the subsequent application of a second coat applied over thefirst coat, which second coat is then dried, ismoistened to a limited extent and is then hot rolled, that is, smoothed, ironed, and burnished under a hot roll. The various features of the general method of providing the desired surface finish on the fiber insulation board co-act one with another to result in a finished product which has a surface finish which scribed as applied in two coats, could of course be applied in a single coat, but it has been found is an improvement over previous more or less ering coat is applied after which it has been.

dried provides an improved base or surface for the application of the second coat of paint applied thereover. The second coat of paint when applied over the first coat results in a smoother and more uniform second coat, which when subsequently hot ironed provides the desired improved surface coating-or finish on the fiberinsulation board.

The coating material which has been just dethat such application does not provide as satisfactory a final finish as does the application of the same amount of coating or paint applied as separate coats. Apparently when a heavy coat of paint is applied as a single coat, the outer surface of such layer of paint tends to follow the contours of the surface over which it is applied much more than does the outer surface of the same amount of coating material but which has been applied as two separate coats. Such condition itis believed results from the fact that when the coating material is spread as a single heavy coating the-entire body thereof tends to follow the contour of. the surface to which it is applied to about the same extent as does a first thin coat, and the'outer surface of the thick coat tends to have the same contour as does the back surface or the'surface which is in contact with the face of the boardto which the coating is applied. A thin first coat however, while it follows the contour of the surface to which it isapplied, tends 'to somewhat smooth up or level off such surface, since the bulk of the material of the thin coat tends to fillup depressions in the surface to which it is applied, and then when the second coat is applied over such first coat there is a still further leveling effect which results in a substantially smooth surface or face on the coating.

Also, whereas a heavy coating might originally be applied to the surface of the fiber insulation board, it is quite difficult to dry a heavy thick coat of the surface finish as compared to the drying of two relatively thin coats, andwhile, of course, it is possible to'dry the coating and apply it as a single coat the time required therefor causes such application to be anything but an economical production operation.

In connection with the above set out process for providing a surface finish on a fiber insulation board or the like, there are several mat ters which it is thought should be pointed out as variations which should not be made from the process as it has been described. It might be thought that to hot iron the first coat would provide a smoother surface on which to apply the second coat, but this is impractical since when such isdone, even after the second coat has been applied and dried, it tends to slide on the undercoat when the second coat is hot ironed.

It is possible under some circumstances to hot iron the second coat, without first fully drying this coating and then remoisten it just before it 3 is subjected to the hot ironing. Attempts to hot iron the second coating without the intervening drying step has not been at all satisfactory since such coating when so hot ironed must be hot ironed relatively slowly in order that it may be completely dried and the results obtained are not entirely satisfactory since there is apparently some slippage of this second coat while it is being hot ironed, which results in a surface finish which is not nearly so satisfactory as the surface finish which results from the preferred method of appli. cation as has been above particularly pointed out.

The objects of the inventions hereof in particular are the provision of a new and improved method of applying'a surface finish to the surface of a, fiber insulation board or the like, and the production of the product'comprising afiber insulation board having on a surface thereof a smooth and substantially level surface finish, which if desired may have a high light reflection or may be colored or tinted to substantially any desired color, dependent only upon, the availability of pigment therefor.

The drawings are a schematic representation of the preferred apparatus, and of which Figure 1 is a. longitudinal cross section, and Figure 2 a plan' view.

In the drawing there is shown diagrammatically the arrangement of co-operating apparatus, the various sections of which will be designated generally by letters A, B, etc., which respectively designate,

A. A coater;

B. Rotating reciprocating brush rolls for smoothing the applied coating;

C. A dryer;

D. A second coater;

E. A second set of reciprocating rotating brush rolls;

F. The second dryer, and

G. The hot roll or hot ironing apparatus.

While the coating applyin equipment items A and D may be substantially any type of apparatus for applyin a more or less uniform coat of coating material, the type which is illustrated is that which has been found generally to be preferable. The coating apparatus as illustrated is a very simple type comprising merely a trough or reservoir III in which rotates a pick-up roll II and which as a consequence carried a film of the coating material on its surface. From the pickup roll II the coating is transferred to a rotating transfer roll i2 against which in turn bears against a doctor blade l3 that serves to transfer the coating material to the surface of the sheet to be coated. The coating material which is picked up by roll I l and then transferred to roll I! and scraped therefrom by doctor blade I3 runs down the inclined doctor blade and drips from the bottom thereof onto the surface of the sheet. The bottom of the doctor blade preferably is serrated or provided with a saw tooth like edge with teeth spaced in the order of inch apart along the edge and having the edges of the individual izeth or serrations inclined at an angle of about The coating of paint like material which is applied to the surface of the fiber insulation board I overcome any irregularities or variations in the application of the coating to the surface of the sheet there is provided to act on the sheet, Just after the coating has been applied, a reciproeating rotating brush unit B which serves to uniformly distribute the coating material over the surface and across the surface of the sheet. This -brushing unit B preferably comprises three rotating brushes H, which extend entirely across the width of the sheet and which as well as rotating at relatively high speed have an endwise reciprocating motion so that the actual effect thereof is that of brushing the coating both in the direction of the sheet and across the sheet. These three reciprocating rotating brushes are slightly spaced apart and preferably they reciprocate one out of phase with another so that a uniform distribution of the surface coating is obtained. Since rotating reciprocating brushes of the type which are used in unit B are relatively well known and are in more or less common usage, no details of the unit will be herein set out, but for a detailed descriptionv thereof such may be found in a co-pending application, the property of theasslgnee of this application, such being the application of Fergus A. Irvine, Ser. No. 377,412; Filed: February 5, 1941, now Patent No. 2,369,342, granted Feb. 13, 1945.

Following the application of the surface coating and the smoothing or distribution of such over the surface of the sheet, the sheet then passes into a dryer unit 0 in which the surface coating is dried. This dryer unit may be of suitable length for drying the surface coating and in practice it has been found that a length of feet for the dryer is about the proper length. In such a dryer the applied surface coating has been dried with the sheet progressing at a speed of about 65 feet per minute and with temperatures in the dryer of around 500 to 600 at the front or entry end, dropping to about 350 at the rear or exit end. The dryer, of course, may be heated in any suitable manner and it is of course to be understood that the speed and temperatures mentioned are merely preferred figures and that other speeds and temperatures may be utilized. For example, dryer speeds of from 50 to 80 feet per minute have been used at various times and dryer temperatureshave ranged from about 600 maximum at the entry end to around 300 minimum at the exit end. The dryer length of course can be varied so that for example if an apparatus is designed for operation at a speed of feet per minute it is probably that the dryer would have to be about 100 feet long using the preferred dryer temperatures as above set out since such greater length of dryer would be required in order that the sheet being dried would be subjected to the drying for the same period as would be the slower moving sheet in a shorter dryer. 4

Following the first drying of the coating sheet in dryer unit C the sheet passes under a second coating unit D which to all intents and purposes is the same as coating unit A and then after the application of the second coat over the first coat the sheet passes under a second set of reciprocating and rotating rolls E, which are preferably of the same construction as the set of reciprocating and rotating rolls B. After the second coat of material is smoothed and evenly distributed by brush unit E, the sheet with its two coat finish passes into a second dryer F in which the second coat of finishing material is in turn dried down to substantially bone dryness.

The second dryer unit F is substantially the same as the first dryer unit 0, but in connection with this dryer unit a drying medium circulating system has been shown. Briefly the drying medium comprises air or actually air products of combustion and water vapor which is circulated into one end of the dryer, is taken out of the other end and recirculated. The-drying medium circulating system comprises a hot duct 20 which discharges into the intake or hot end of the dryer and a warm duct 2| which leads from the exit or cooler end of the dryer. the warm duct 2|.

not end of the dryer. -To conserve heat there may be supplied a duct 21 which carried waste heat from the hot ironer unit G to discharge this waste heat into the duct 25, leading to the circulating fan 28. Further there may be provided in warm duct 2|, a damper '28 and vent 29 which as is obvious may serve to regulate the amount of war medium being returned to and circulating in the system or which provides for the intake of cool external air into the circulating system should such be required to maintain the drying medium at the proper temperature.

A sheet of fiber board with its two coats of surface finish which have been dried in accordance with the foregoing description, as it comes from the second dryer unit F preferably passes under a water spray 40, which sprays on the surfaces of the coated sheet a predetermined small amount of water which serves merely to moisten the surfaces of the applied coating. After the sheet has been moistened as described, it then passes to a hot ironing unit G which comprises a rotating smooth surfaced cylinder member 45 which is preferably from about 36 to 60 inches in diameter and which is heated both internally and externally by gas jets 46 and is preferably provided with a heat conserving housing 41, which tends to confine the heat of the gas burners to the surface of the hot roll 45 so as to conserve the heat spread by the gas burners 46.

The effect of the hot iron on the coated sheet, the surface of which has been moistened as mentioned, is to vaporize the moisture in the coating and to raise the temperature of the coating and of the immediately adjacent portions of the fiber board sheet, and this brings about a softening of the surface fibers of the sheet and a softening or plasticizing of the coats which have been applied to the surface of the sheet. The hot roll then as the sheet passes under it presses down the softened surface fibers of the sheet, that is, it exercises an ironing effect which smooths the surface of the board in pressing down the surface fibers thereof to a smooth and level surface. The coating which has been applied to the surface of the sheet is likewise ironed and smoothed and this coating on its back side is forcefully driven into any spaces or crevices between the surface fibers of the sheet so that it acts to adhere or anchor the surface fibers of the sheet in their ironed down condition.

As the coated sheet passes under the hot iron the heating and vaporization of the moisture in the coating soften the surface coating and the adjacent fibers, the continued heating thereof under the iron, due to the limited amount of moisture which has been added causes this moisture to evaporate from the coating and the surface of the sheet and the coating and the surface of the sheet consequently are thoroughly dried out. -The effect of this drying out of the coating and surface fibers of the sheet under the influence of heat and pressur under the hot roll results in a complete ironing or pressing effect wherein the coating and fibers have been softened by the hot vapor, have been smoothed or pressed down into place to a smooth and level surface and finally are dried in such state whereby they retain the effects of the hot ironing or pressing to result in a product having an ironed surfacewhich is smooth and well bonded.

The result which is obtained by the procedure as above described is very different from that which is obtained from a mere coating or painting of the surface of the fiber insulation board sheet. In merely coating the fiber board sheet the coating materials applied tend only to cover over the surface with a more or less uniform coating which generally speaking follows the contour of the surface to whichit is applied, and such a coating while it might appear to have a smooth surface does not actually have a really smooth surface since the particles of filler or pigment therein actually produce a rough surface for the coating which if highly magnified would appear very much as a pebbled surface. By the hot ironing operation which is utilized in connection with this invention, the fibers at the surface of the fiber board sheet are ironed down to a relatively smooth surface and the coating is ironed out over this surface as a relatively uniform and Y smooth coating and finally the effect of the hot ironing is to tend to flatten out and smooth the filler and pigment particles in, the coating so that the surface of the coating is actually relatively smooth, or what might be stated to be a burnished surface.

While above there has been particularly described and disclosed apparatus forand a procedure involving the application of a two coat coating to the surface of the fiber board, which two coats are subsequently hot ironed, such constitutes a description of what might be termed theultimate process, that is, this is a process to produce a relatively heavy surface coating or finish on the fiber insulation board and one which will have a high degree of surface smoothness. high light reflectivity and other physical properties of the highest degree.

As a feature of the process of this invention there may be utilized only what might be termed the basic or first phase thereof, that is, the hot ironingof the surface of a fiber insulation board for merely smoothing the surface butnot including the application of a coating to such surface. In the exercise of such phase of the procedure hereof there may be utilized only the hot roll unit thereof of. the apparatus utilized in conjunction with the water spray or distributing head 40. In such case the fiber insulation board, the surface of which is to be hot ironed will with its normal moisture content of about '7 to 9 per cent or thereabouts. be passed under the spray head or distributor 40 for the application of a limited amount 1 of water applied to the surface of the sheet, such amount of water preferably being that amount which will moisten the surface fibers of the sheet without providing any excess of free water on such surface. The such amount of moisture of water applied to the sheet to merely moisten the surface fibers is approximately the amount which would be retained were such surface substantially be smoothed due to the ironing effect of the hot,

roll on the moistened surface fibers thereof to result in a smoothed surface sheet in which the moistened surface fibers, due to the eflect'of the hot r011, softened by the vaporization of the moisture present, have in such softened condition been ironed or pressed down to a smoothed surface and then dried in such condition, whereby the resulting sheet has a smooth ironed surface in which the surface fibers are pressed down to a substantially uniform and smooth surface which tends to maintain such condition due to the fact that the moisture has been dried from the fibers while they are so pressed down and smoothed.

In connection with the application of a two coat coating to the surface of the: fiber board as has heretofore been described, various such surface coatings can be utilized, but preferably such coaters comprise basically a filler or pigment and adhesive and water as the suspending agent or.

carrier. Several formulas involving the such ingredients for utilizing different adhesives and in which certain of the ingredients are identified by their well known trade names are as follows, in pounds per gallon of the coating medium.

In connection with the above formulas it is, of course, to be understood that such results in a white coating or surfacing of the fiber board sheet due to the characteristic of the white color of the lithopone filler or pigment, but however, if some other color for the coating is desired then a suitably colored pigment may be substituted in all or in part for the lithopone to produce a coating of the desired color, and as an example of a coating medium which is colored and which incorporates an amount of very finely divided fibrous filling the following is given.

Titanox it {added to control light reflec- In applying the two coats as has been described herein, it is of course. to be understood it isto be understood are of 8 that the first coat applied to the surface may, if desired, be one of the coats 1 to 4 inclusive as a base coat followed by the color coat, an example of which was above given or, of course, if desired both of the coats applied can be of the same composition.

In addition to the type of coating mixtures which have been above particularly set out, the inventions hereof in a further utilization of a phase thereof may be employed for providing a smooth hard surface on the fiber board sheet, which smooth and hard surface extends to a limited depth into the body of the sheet. In providing such a surface on the sheet the coating materialwhich is used is an ordinary thin varnish having either a gum or resin base and the base gums or resins may be applied to the surface of the sheet in a solvent. In providing such a hardened surface on the sheet the coating -material may be applied either in one or two coats, although preferably as a two coat application since a better and more rapid drying of the coats can be obtained if they are applied as.relativ ely light coats, which individually may be more readily dried than an equal amount of coating material applied as a single heavy coating.

The gums or resins used in this type of coating the type which are either thermo-plastic or thermo-setting, and as an example, the various gums and resins included in an ordinary varnish are of the thermo-plastic type, whereas a synthetic resin such as Bake-olite resin used for the surface coating would be an example of a thermo-setting resin. In applying a coating of this type to the surface of the sheet a varnish of spreadable consistency may be applied to the surface, either by one coat or two coat application as has been mentioned, and applied at the rate of from five gallons to twenty gallons of such varnish pe'r 1000 sq. ft. of surface. The such varnish applied to the surface penetrates into the sheet to a depth of up to about 1%". A fiber board sheet having a surface application of varnish as has been described, which has been dried by being passed through the apparatus disclosed herein, but without the application of moisture to the surface of the coating will when such is passed under the hot roll result in a smooth and hard surface on the fiber board sheet. which hard surface extends more or lessinwardly into the sheet.

When such a dried sheet is pressed under the hot roll the effect of the heat is to soften the gums or resins, to iron down the surface fibers, and if a thermo-setting resin is used. to cause the conversion thereof to the set condition. However. if a thermo-plastic gum or resin has been used it is, of course, understood that while the action under the hot roll is to soften such and to smooth or iron down the surface of the sheet, that. however such gums or resins will not be set due to the heat of the hot roll, but that such will set after the sheet issues from the hot roll and cools down.

There is one particular fea ure of the application of thesurface coating to the fiber board sheet which has not as yet been mentioned, but which in connection with the application of certain surface coats is of considerable advantage. This feature of the two coat application of the surfacing coating is in connection with the application of surface coats which are caused toreact, one with the other to produce a finished surface coating which has certain characteristics which cannot be otherwise obtained. For example, inutilizing the process hereof there can be applied to the magnesium chloride or urea and formaldehyde or other like combinations. In each of these illustrations just above given it is obvious that the chemical additives react to the conditions of hot rolling to aiiord water resistance to the finished ironed coating and to constitute an additional adhesive binder within the coating itself.

It is, of course, to be understood that the fore-.

going description is directed to those who are skilled in the art to which thi appertains, and that well known details of the operation and procedure have been omitted in the interest of describing the invention hereof rather than obscuring the inventions in a maze of known detail. Of course it will be obvious that suitable conveyors such as indicated by numeral 50 will be provided for carrying the fiber insulation board sheets through the series of apparatus disclosed in the drawing and that suitable connections by belts, gears and the like are made to suitable lplower sources such a shafting, motors or the It is believed that it will be obvious to those skilled in the art that this invention relates particularly to the application of a relatively heavy surface coating applied to the fiber insulation board, which is a coarse fibered product and in connection with which the coating thereof is a matter entirely different from the coating of a fine fibered paper sheet. There is a difficult problem involved in applyingand obtaining a smooth and unifrom coating on a coarse fibered board sheet, which difficulty is complicated by the fact that such sheets are normally about one-half inch thick and are soft and yielding. Such fiber board sheets cannot be hot rolled with the relatively high pressure, which is used in finishing coated paper, without crushing the interior thereof. in particular if such fiber board 50 sheet is moistened to any appreciable extent. The

disclosed inventions hereof et out a process and procedure for applying to the surface of a fiber board sheet a two coat application of a coating material, which procedure of coating affords a smooth and uniform coating on the sheet and which two coat procedure involves the application of a first coat with the subsequent drying, followed by the application of the second coat, and its drying, and finally the moistening of the surface of such coats and the hot ironing thereof.

The inventions having been above described and the methods of application having been set out in detail, what is clamed is:

In an apparatus for applying a surface finish on fiber insulation board the combination comprising means for applying a fluid coating over the surface of a sheet of fiber insulation board, means for drying said fluid coating, means for applying a second fluid coating over the surface of the first fluid coating, means for drying such second fluid coating, means for supplying moisture to the surface of said second coating and heated ironing means for smoothing and ironing said surface coating applied to the fiber insulation board and a conveyor in operative relation with respect to said various means for conveying the fiber insulation board being treated successively through the said plurality of means operating thereon.

CARL G. MUENCH.

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

UNITED STATES PATENTS Number Name Date 615,446 Goldsmith Dec. 6, 1898 693,189 Thomson Feb. 11, 1902 1,218,474 Ross Mar. 6, 1917 1,557,485 Turner Oct. 13, 1925 1,589,537 Lukens et al. June 22, 1928 1,957,369 Swan May 1, 1934 2,230,876 Wysong Feb. 4, 1941 2,304,819 Grupe Dec. 15, 1942 FOREIGN PATENTS Number Country Date 5,191 Great Britain Mar. 20, 1884 288,221 Great Britain Apr. 9, 192'!

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