US2581993A - Process of making acoustical tile - Google Patents

Description

Jan- 8, 1952 l G. s. wlLLr-:Y ErAL 2,581,993

PRCESS OF MAKING ACOUSTICAL TILE original Filed sept'. 17, 1943 ,In venian; Gra-772251 MZIJZZ@ I Orca Patented Jan. 8, 1952 PROCESS OF MAKING ACOUSTICAL TILE Grant S. Willey, Chicago, Ill., and Orcutt W. Frost, Gaston, Oreg., assignors to United States Gypsum Company, Chicago, Ill., a corporation f Illinois Original application September 17, 1943, Serial No. 502,728. lDivided and this application December 6, 1948, Serial No. 63,718

2 Claims. 1

This invention pertains to an acoustical construction. More particularly it is directed to a fibrous acoustical base having a decorative coating receptive surface and the process of making the same.

This is a division of the application for Letters Patent, Serial Number 502,728, filed September 17, 1943, and issued as Patent Number 2,459,121 on January ll, 1949.

Though the principles underlying this invention yare adapted to the preferred type of an acoustical base comprising brillated lignocellulosic materials felted in a sheet form in accordance with conventional' methods of formation, it is not the intention to limit the same to the preferred embodiment, since obviously, with slight embodiment the depth to which the grooves are cut in the acoustical tile body. y

Figure 3 is taken along lines 3--3 of Figure l, partly broken away to show a section through one of the grooves and indicate but one type of periphery or are impressed within the acoustical base.

Figure 4 shows in a partly broken away section another type of arc of a semicircular nature, that may be also impressed depending on other relative conditions inherently present in the acoustical base.

Figure y5 illustrates ina transverse section another modication of this invention.

An acoustical base I0, preferably comprising felted lignocellulose fibrous materials, such as used in conventional insulation board is treated to the simultaneous application of heat and pressure to develop in the surface thereof an autogenously formed thermoplastic resin that not only binds the fibrous material on the surface I2 to form a more dense and decorative medium receptive plane but also maintains the contiguous area I2a at a greater density in comparison with interior I2b. The development and formation of this autogenously created thermoplastic lignocellulosic resin is highly desirable, since it provides a smooth surface for the subsequent application of paint, lacquer and other decorative finishes without undue difficulty. A surface of this nature though it is somewhat impervious to sound, it is, however, more protective, resistant to sculiing and denting, and more easily adapted to use under erection conditions.

To form this surface it is desirable that the lignocellulosic blanks be placed in contact with a heated surface maintained under very slight pressure to prevent undue compression in the interior I2b of the acoustical base I 0. If great pressure is applied the interior I2b has a tendency to densify as the heat from the surface penetrates the depth of the acoustical base Ill. In practice it was found desirable to use a temperature of about 485 F. to catalyse and aid in the formation of the autogenously created lignocellulosic resins on the surface I2, and the surface contiguously underlying area I 2a. The length of heat and pressure application will vary withv the nature of the base. Though it is desirable to pre-dry the acoustical blanks, it is not essential since the open, cellular structure permits the ready escape of gases and water generated during the autogenous formation of the thermoplastic ligno-cellulosic resin.

A series ISa, b, c, d, etc. of parallel slots or grooves I6 are impressed upon and through the surface I2 into the interior I2b of the acoustical' base I0. In order to obtain the maximum benefit, it is desirable to form the grooves I6 as deeply as possible to provide the maximum surfacearea capable of absorbing sound. In any event it is desirable that the depth of the cut or groove I6 be at least one half of the thickness of the acoustical base I0.

In practice the parallel grooves are formed in the acoustical base I0, and extend approximately one third of the Way across the face I2 of the acoustical base I0. At this point 24, another series Ia, b, c, d, etc. set off or staggered in relationship to the previous series ISa, b, c, d,etc. is started across another approximate third of the way of the face to the point 26. The ends of theV series I8, a, b, c, d, etc. is slightly overlapped but not joined by endsof the series IGa, b, c, d, etc. at point 24, and by the ends of the series 20, a, b, c, d, etc. at point 26. This type of construction provides for more acoustical base material between the grooves I6 and I8 and prevents a transverse plane of cleavage or weakness along successive grooves at this junction. Obviously other patterns employing these principles can also be made.

To aid and reinforce this junction as well as for other reasons given below, the end sides30 of the grooves IIS near the points 24 and 26, as Well as at Vthe edges of the acoustical base II), gradually slope 32 in aforrn of an arc to the bottom 23 of the groove. The substantially elliptical type arc of the groove (as shown in Figure 3) is obtained by impressing the cutting means (not shown) into the interior |25 and thn o'fig the cutting means longitudinally the desired distance. This particular type of groove 'construction is particularly useful in 'slottiii'g acoustical bases having a thickness of less than one inch.

Obviously another type is the circular arc yas shown in Figure 4. If relatively small diarileter cutting saws are used, the proper depth can be readily reached without cutting longitudinally.

To nish the tile a bevel I!! can be formed on all edges either during the pressing operations or at subsequent stages of operation before the application of coatingV compositions to the formed surface.

A 's1ot'22 is also'ferned in at least two of the sides of the acoustical base Iii to provide a means for insertion of a bridge clip (not shovvn) or other suitable retaining means, to'at'tachV the tile rne-V chanically to the surface, such "as a Wall or a ceiling. in praetice, it 'frequently isdesirable to use an adhesive vbacking on the tile, vWhich is then 'erected and retained in place by the adnsive. f

The slope v32 curves gradually to the bottom 28 of the groove `i'hc'iugh the interior i215 of the acoustical b'ase El is generally darker in color, it is; however, not noticeable at the distance normally encountered bet'tveen the eyes and the ceiling or Wall upon'vvhich ,it is installed; ln the course of applyiigthe (paint, there is a tendency for the excess amount to gradually ow down the slope and come to the surface i2 at points 24 and 26. It should be noted that an acoustical iteni when in use as for instance` on a ceiling is inverted and theslots or grooves I6 face the source of sound. Under those conditions, as Well as when it is used Aon the Wall, the excess of the coating composition"Willobviously under inuence of gravity flow down thevs'lope 32 lto the surface I2. This 'flow 'not only decorates the visible part of the groove and therebyblending it into the fore'groiindto decrease its visibility, but also prevents Vexcessive accumulation oi; the coating composition Within the groove itself and thereby destroy or impair Vits sound absorbing characteristics'. y Y u w At tinies'it may be desirable to increase still further the s'd absorption and decrease the eiect of the depth shadow of the groove. This can be readily accomplished by 'slotting the grooves ls, jdisgonauy from the surface lf2, into the body I2b as shown in` Figure 5. Of'course, when this, particular rnodi'cation isvderectedvon the wan it isdesi'rabl that the grooves point .downwardly to eliminate collection vof dirt and facilitate future redecoration.

assises fgrsbveis In making acoustical tile according to the prin;y ciples underlying this invention, the surface of a brous base such as lignocellulosic felted sheets isA simultaneously treated With heat and pressure under conditions mentioned previously. In practice it is preferred to mold simultaneously the bevel I4 While heat and pressure are applied to This process provides a smooth, suitable lcoating receptive surface. In the preferred iiiodebfoperatiom the Whole series of 4 aneously cut by means of the desired nu'nit'ier of high speed saws. Each series of saws is mounted on a common shaft or spindle which in turn is driven by a high speed electric motor, The slotted or grooved acoustical tile is then'decoratediiithe customary manner, allowed to dry Vand packaged for further disposition.

Though the above description describes in considerable detail the otstanding features and characteristics of the principles underlying this invention, it is obvious that many adaptations, extensions, modications and uses can readily be discerned by a person skilled in this art, and it is not intended to be limited to the speciiic leinbodirnents described herein but only Aby the spirit of principles of this 'inveti'n'as indicated ini the attached claims.

1. In thev process of making a slotted acoustical tile, the steps of dnsiying the surface o'f Va brous base by the application of heat and pressure to form a skin coat tl'1`re ')ri, penetr'atinsr the said vskin coat by'neans of a seriesfof parallel, cutting'r'neai'is to Vthe desired depth. p

2. The proc'ssbf making` a slotted acoustical tile comprising the vsteps f applying a heated platen inaintained at a temperature of riot less v than 350 F. to the surface of a fibrous ligncellulosic base board, simultaneously ei'i'ertirig* thereon a slight pressure to'cornp'ress said surface, ymaintaining said 'heat and said pressure on said surface for a suiicient length of tine to coalesce the fibers in 'said Vsurface until d ensifled, coolingrtlie said den'sified 'surface and penetrating Vto the desired depth the Ysaid surface by nas of a series of parallel cuttingrneans.

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