US2711120A - Method and apparatus for watermarking paper - Google Patents

Description

June 21, 1955 MacLAUR|N 2,711,120;

METHOD AND APPARATUS FOR WATERMARKING PAPER.

Filed Sept. 6, 1947 2 Sheets-Sheet l INVENTOR JAMES D. MacLflURIN BY @14 flaw, m my ATTORNEY June 21, 1955 J MacLAURlN 2,711,120

METHOD AND APPARATUS FOR WATERMARKING PAPER Filed Sept. 6, 1947 2 Sheets-Sheet 2 INVENTQR JAMES/D. MacLAURlN.

ATTORNEY$ METHOD AND APPARATUS FOR WATER., MARKING PAPER I reach ofthe'" belt 'asit leaves the pulley 3, just clears James Donald MacLaurin, East Orange, N. 1.;

Application September 6, 1947, Serial ll Claims. (CL 92-38) This invention relates to method and apparatus for watermarking paper and has for its principalobject the provision of a method and apparatus for watermark ing paper whereby a distinct, definite, sharply defined watermark can be created in a paper web during'its formation in the paper machine while traveling'at a' high rate of speed. 1

A further object of the invention is to provide a meth- 0d and apparatus whereby watermarks in'a plurality of colors can be formed in the paper without retarding the speed of the paper machine or in any way interfering" with its operation.

A further object of the invention is to provide an apparatus for obtaining the abovementioned' results which is of simple and inexpensive construction and which can be readily applied to existing paper machines without change in the machine structure and"w ithoutin any way interfering with their operation. In the accompanying drawings I have illustrated several forms of my improved apparatus designed, fre spectively, to produce watermarks without additional color, watermarks with a single col0r, and watermarks in difierent colors. In the said drawings: v Fig. 1 is a longitudinal vertical section of an attachment to be applied to a paper machine over thetraveling screen to produce Watermarks without the addition of color; Fig.

Fig. 3 is an enlarged perspective view partly in "sec tion of a portion of the traveling belt of the attachment and the underlying paper web and screen-of the-paper machine; i

tion wherein the watermarks are formed -by-the*addition of a single color; i

Fig. 5 is a view similar to Fig. 1, wherein. the water marks are formed in a plurality'of-colors; f

Fig. 6 is a plan view of. the traveling-belt arm proved attachment with the overlying color moved;

Fig. 7 is a horizontal sectional view:on line '7 7.?of 5; .TE1 f.' Fig. 8 is a plan view ofthe paper web showing theprogressive steps in the formation of the watermark; and. Fig. 9 is a detail view of the valve usedtinmegulating the delivery of the several colors making up theiwaterv mark. f Referring to the drawings,- '1 indicates the screen: oh the paper machine upon which the pulp on thebeatersis deposited in the usual manner. The screen 'runs over suction boxes, not shown, and my watermarking attachment may be positionedover the screenwhere the sucftion box is located or at :a' more advancedpositioninthe path of travel of the screen. The layer of wetrpapert pulp carried by the screen is indicated at 2.;-

My -1mproved watermarking. attachment; ,embod two pulleys 3 and 4, respectively, whicharecontinuops 2,711,120 Patented June 21, 1955 w 2 lyidriven 'by gearing, 'not shown, in synchronism with the screen 1 of the paper machine at a speed such that the'belt 5 carried by the pulleys travels at the same speed as 'th'e'sc'reen of the paper machine. The pulleys 3 and 4"arepositioned above the screen so 'that'the lower the layefijof pulp onfthe screen. 7 Due to the slack in the beltitwill throughoutth'e majorportion of its travel from pulley 3 or pulley 4, rest lightly on the layer of pulp] An adjustable idler roller 6 is provided between andfabove the two tension of the belt. p

' The belt5 is preferably a flexible metal belt and openrags ofthe shape of the watermarkto be formed are cut in the belt as indicated at '7; In effect the belt constitutesa traveling stencil for forming the watermark.

Overlying'the lower'reach of the belt between the pulleys 3 and 4 is an air box 8 containing a series of nozzles, shown as four in number, each of which is connected to a source of air pressure 9, not shown, and eachjoffwhich is provided with a discharge slot 10 of a length"' somewhat greater than the width of the stencil opening inthebelt 5.

.j :The bar 8 is also provided with a discharge opening 11 to allowfor the escape of air discharged into the box through the. nozzles, to thereby limitthe degree to which the air pressure will build up in the box.

"The'operation is as follows The belt 5 is, as stated above, given the same rate of speed as the screenof the paper machine so that, there is no relative movement between the'stencil which determines the shape of the watermark and the paper web. .Consequently the operapulleys in order to regulate the tion ofthe apparatus is not aifectedfby the rate of travel sure in the'box against the web 'of pulp and as the sten- ""In Fig. 4

oil; openings advance under the successive nozzles the pulp underlying the stencil openings will be exposed to the'jstr eamsbf air discharged from the slots 10 of the nozzles ,9. "A number of nozzles are provided so that 1 mevaseity of each stream of air can be kept relatively 2 is a horizontal section on line 2-2 of Fig. 1;}

low so as not to" disrupt the fibres forming the layer of pulp. Theimpact of theair streamsserves to compact I rality of nozzles the vnumber in use fmay be varied to give Fig. 4 is a view similar to Fig. l showing'amodifica--- any desiredde greef of compression to the pulp without employing air stream velocities which would adversely ai fc he properformation of the paper. When the appearance as the conventional watermark which bypres-l an panama-storm d by pressing a metal marking member' rthe proper outlineagainst the travelingw'eb' mp ..l,. a a a i v I have illustrated a modification of the appa-Q ratus shown in Fig. 1, for applying the watermark not only air pressure, but by the addition'of a filler which may be either white 'or colored. shown' -in Figf 4- thebelt '5 is supported andd'riven'by'the' pulleys 3}"4' and 6-in the same manner as'idthe' "construction illustrated in Fig. 1, exceptthat-pulleysS and 4 arespaced slightly away from thesurfa'ce ofthe screen and idle pulleys 3 'and 4 are provided between the pulleys"3"*and"4 and the air box to hold the stencil in I contactwiththe pulp on the screen. The advantage of oyerhesdhe lower reach of the belt 5 between the pulleys,

dried' and calendered in the usual manner, the t I watermarks'in the. paper willhave substantially the same In the modification the belt 5 forming the bottom wall of the box. Projecting into the box are two air nozzles 13 each of which is provided with a discharge slot 14, the slots, however, being disposed in the side walls of the pipes instead of; in the bottom wall as in the construction shown in 1. In the apparatus shown in Fig. 4 the air delivered to the pipes 13 carries. a water suspension of pigment, for example, finely ground clay, calcium carbonate 01 any other materials suitable for fillersin thernanufac: ture of paper. The discharge opening 15 of the box, 12 will be regulated to build up inthe box thedesired pres' sure so that as the web and belt travel under the box some of the color in suspension in the boxwill bede, posited in the stencil openings of the belt and will be pressed into the paper pulp by the pressure in the. ,air box.

When the paperis dried and calenderedin the usual manner the watermark will appear in the paper as an opaque and,'if desired, colored design which is in the paper itself as distinguished from printing on the surface of the paper. The paper itself will be no thicker in the watermark areas than elsewhere, but will be denser to the extent of the added filler which forms the watermark.

In Figs. 5 to 9 inclusive I have illustrateda modifica tion of the apparatus whereby watermarks in a plurality of different colors may be obtained. As here shown there is a traveling belt 16 similar to the belt 5, the belt being continuously driven by pulleys 3 and 4 in the manner already described. The stencil openings 17 in belt 16 correspond to the full size of the area to be watermarked and for simplicity of illustration we have shown the watermark in the form of a circle or disc. That is to say, the stencil openings 17 in the belt 16 are round holes extending longitudinally of the belt.

Overlying the lower reach of the belt between the pulleys 3 and 4 is an air box 18 containing a series of air nozzles each of which is composed of two concentric pipes as illustrated in enlarged detail in Fig. 9., The inner pipe 19 of these nozzles is providedv in its lower wall with a longitudinally extending slot 30 oft-a length at least equal to the width or the diameter of the stencil openings. The outer pipe 20 of the nozzle is provided in one wall with a similar slot 21, and this pipe 20 is pro-' vided with a driving gear by means of which it is continuously rotated around the pipe 19 as an axle in timed relation with the passage of the stencil opening 17 be; neath the nozzle. 7 v i The air box 18 in this modification of the invention is provided with a bottom piece 22 in which are cut open ings of less area than the stencil openings 17, but positioned to register with a portion of the stencil opening at one instant during the passage of the stencil opening as the belt and the web of, pulp move in synchronisnr with the screen of the paper machine beneath the box 18. The rotation of the sleeve 20 is so timed with the movement of the stencil belt that at this instant of registration of the openings 23 with the openings ,17 the slot 21 in the pipe or tube-20 will register with the fixed slot in the pipe 19 and a blast of air containing color will be directed through the openings 23 and the registering openings 17 against the underlying web.

To limit the spread of the color beyond the outlines of the openings 23 the box 18 is preferably provided with a suction exhaust whereby the instant the blast .ofairis cut oflf by the rotating sleeves ,20 the color will be .cxhausted from the box.

In the arrangement shown in the drawings the .first the second air nozzle a strip of color of a shape corresponding to the middle portion of the circle is applied through the second opening in the bottom of the box.

Likewise when the opening 17 comes into registry with the third nozzle in the bottom of the box. 18 which over-.

lies a reversed segment-shaped opening, a third color, will The-fourth opening in the bottom of the box 18 is circular in area and overlying this opening is an air nozzle having afixeddischarge opening through which air withontcolor is discharged against the pulp and its layer" of pigment to thereby press the pigment into the When the paper is dried and calendered it will contain at intervals watermarks of the desired configuration, portions corresponding in shape to the openings in the bottornof the box 18 being in different colors. ,The pigrn ts making up the colors may be chiefly white pigment with just sufficient color to give a different tint (to thedifierent areas of the watermark, or, if de-.

sired, .thepigments may be of pronounced and contrastingshadesto constitute in effect a printed area.

In order to give sharper lines to the different colored areasof the watermark the box 18 may be reciprocated in a plane parallel with the movement of the belt 16, whereby the box 18 moves with the belt 16 during the entire periodthat the valve in the overlying nozzle is opening 23 is in the form of a segment so that there willv be applied to one side of the circular shaped opening 1'! a segment of color, the balance of the area ofitheopen ing 17 being protected by the imperfora-te portions of the bottom of the box 18 from receiving color from this first nozzle. As'the portion of the belt 16 containing the opening 17 through which the color has been' 'discharged from the first air nozzle comes into registry-with open, and is then returned to its initial position before he talvecpen a se m In Fig; 5.1 have shown a cam 24 driven by the shaft of the pulley 4, and a connecting rod 25 for effecting this movement. With such an arrangement the blast of air containing color to be applied can be somewhat pro longed to insure that an ample amount of color will be applied during the passage of the web while at the same a time the outline of the area to which the color will be applied will besharply defined.

vdllVhile ,I have described my improved method and apparatus as a method of watermarking, it will be understood that the method and apparatus may be used for actualjprinting. The stencil openings in the belt need not constitute a repetition of the same pattern but may form any desired legend or design which it is desired to apply to the paper, and the color used may be a pronounced.color contrasting with the color of thepaper itself .59 @Sxto printthe paper with any desired legend or design; .For example, the entire letterpress and designs of a label may be successively printed on the paper by my invention during the manufacture of the paper so that (the paper machine itself will produce a finished label requiring. no additional printing.

It will also be understood that the features of the j marksto beformed, a shield overlying said belt having. openings corresponding to difierent areas of the open-v ings in said belt-means for reciprocating said shield to move thesame insynchronism with said belt during a portion of its reciprocating movement, and means for discharging different colorsthroughsaid openings during the passage of the openings in the belt.

2. Themethod of watermarking paper on the screen ofa paper machine which consists in moving. a shield having stencil openings in synchronism with said screen and subjecting-the pulp exposed through said openings to gaseous fluid pressure.

3. A water-marking attachment for paper machines comprising a belt, means for supporting said belt to travel in a path closely adjacent to the upper surface of the screen of the paper machine and parallel thereto, said belt having designs formed therein corresponding tothe mark to be formed in the paper, a box overlying said belt the bottom of said box being open on its under side with the portions of the box surrounding said opening in close contact with said belt, and means for supplying said box with air under pressure to thereby press the belt against the pulp on the screen and also exert pressure against the pulp underlying said designs, said means comprising pipes connected with a source of compressed air, said pipes having discharge openings directed toward the exposed upper surface of said belt.

4. A water-marking attachment for paper machines comprising a belt, means for supporting said belt to travel in a path closely adjacent to the upper surface of the screen of the paper machine and parallel thereto, said belt having designs formed therein corresponding to the mark to be formed in the paper, a box overlying said belt the bottom of said box being open on its under side with the portions of the box surrounding said opening in close contact with said belt, means for supplying said box with air under pressure to thereby press the belt against the pulp on the screen and also exert pressure against the pulp underlying said designs, said means comprising pipes connected with a source of compressed air, said pipes having discharge openings directed toward the exposed upper surface of said belt, and means for adding coloring matter in vaporized form to the air discharged. 5. The method according to claim 2 wherein the gaseous fluid consists in part of a colored vapor.

References Cited in the file of this patent UNITED STATES PATENTS 507,608 Barnes Oct. 31, 1893 1,211,739 Miser Jan. 9, 1917 1,280,524 Murray et a1 Oct. 1, 1918 1,581,004 Erkens Apr. 13, 1926 1,587,700 Daniels June 8, 1926 1,785,833 Keck Dec. 23, 1930 1,787,218 Trask Dec. 30, 1930 1,864,726 Griffen June 28, 1932 1,881,404 Hadley Oct. 4, 1932 1,910,670 Blaser May 23, 1933 2,133,516 Huebner Oct. 18, 1938 2,270,464 Nash Jan. 20, 1942 FOREIGN PATENTS 221,311 Great Britain Sept. 11, 1924

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