US3287207A - Method of distributing siliceous fillers uniformly throughout a water-laid web while the web is on the fourdrinier wire - Google Patents

Description

R. O. TREAT METHOD OF DISTRIBUTING SILICE Nov. 22, 1966 3,287,207

ous FILLERS UNIFORMLY THROUGHOUT A WATER-LAID WEB WHILE THE WEB IS ON THE FOURDRINIER WIRE Filed April 17, 1964 2 sheets-sheet 1 INVENTOR RALPH O. TREAT Nov. 22, 1966 7 2 OT mw ,wEm 7HRS 8mm 20 t ,RRe mmm MT &- 4% o ww Z Um B .V N M N @N RW B O Wow 0 R. m 9m LAID WEB WHILE THE vL nzw METHOD OF DISTRIBUTING SILICE A WATER- Filed April 1.7; 1964 United States Patent METHOD OF DISTRIBUTING SILICEOUS FILLERS UNIFOI-ZMLY THROUGHOUT A WATER-LAID WEB WHILE THE WEB IS ON THE FOURDRIN- IER WIRE Ralph 0. Treat, Havre de Grace, Md., asslgnor to J. M. Huber Corporation, Locust, N.J., a corporation of New Jerse y Filed Apr. 17, 1964, Ser. No. 360,582

3 Claims. (Cl. 162-186) This invention relates to a novel method of adding inorganic fillers to paper.

Paper is formed in modern paper mills by depositing fibers on paper machine wire. This is accomplished by forming a furnish of cellulosic fibers in water with retention aids, pigments, flocculating agents, binders and other additives used in papermaking.

The furnish is initially about 95 to 99% water. After treating the furnish to achieve the proper formulation it is contacted with the paper machine wire. The cellulosic fibers are deposited on the wire as a result of gravity and applied vacuum which pulls the water through the wire and deposits the fibers uniformly on its surface.

Fourdrinier machines utilize table rolls, suction boxes, and suction couch rolls to aid in water removal. If the suction is increased at any of these points, an increase in drainage occurs with a resultant compact sheet.

Fibers are deposited by gravity or suction on cylinder machines with the head caused by the difference in liquid levels inside and outside the cylinder mold.

Generally, filled or pigmented papers are made on the Fourdrinier machine.

There is a short interval, at the beginning of the run on the Fourdrinier, during which the finely divided matter such as fillers, fibers and additives, passes practically unhindered through the wire. Soon thereafter, a mat starts to form on the wire and drainage of the water has to take place through this mat.

The efliciency 'of the mat as a filter depends among other things upon its thickness, the nature of the fibers, and the speed of the wire. Too much suction or vacuum on the table roll, the suction boxes, and suction couch roll may be responsible for sucking loose some of the fine particles of filler and fiber which have been deposited in the sheet, resulting in a condition known as two sided ness.

The retention of the fine colloidal or near colloidal matter such as inorganic fillers presents a problem because they are finer than the pores in the wet fiber mat. This is a problem of economic importance because for the most part the pigments and fillers constitute the most expensive part of the paper furnish.

As a rule, inorganic fillers are added to the furnish in the beater or fan pump and travel from there to the head box along with the furnish. From the head box, the furnish is flowed onto the wire to form the web. This type of paper making process destroys functional aggregates in low refractive index pigments, thus reducing efiiciency for developing optical properties and creates problems of filler retention as well as fiber fines retention, two sidedness or unequal brightness between the wire and felt sides of the sheet. This process also requires considerable time for the system to equilibrate, resulting in filler losses at the start and finish of a run.

Another process by which attempts have been made to eliminate these problems is that in which fillers have been added directly to the web.

This is accomplished by spraying the filler onto the :lip of the headbox or slice, or further downstream on a deflector with a lip. By this process, the filler contacts the web and generally deposits on the surface thereof.

The water is removed from the web beneath the surface on the wire side leaving the filler undisturbed. This, of course, results in extreme two sidedness caused by unequal distribution of the filler.

The primary object of this invention is to provide a method for economically and efliciently filling paper with inorganic filler pigments.

Another object of this invention is to provide a method of producing filled paper with a minimal two sided effect.

A further object of this invention is to provide a method of filling paper that results in an even distribution of the filler throughout the finished paper.

A still further object of this invention is to provide a method of filling paper with inorganic filler pigments whereby the optimum aggregate size in the fine particle low refractive index pigments is retained.

Other objects and advantages of this invention will become apparent from the following specification taken in the light of the drawings in which:

FIGURE 1 is a schematic drawing of a typical spray distribution system used in this invention,

FIGURE 2 is a view of the spray nozzles in relation to the paper machine,

FIGURE 3 is a view of the spray system, and

FIGURE 4 is the cutaway view of the spray line.

I have discovered that an aqueous slurry of a paper filler pigment can be sprayed into the moving Web at a particular location on the equipment and under special conditions to insure an even distribution of the pigment throughout the paper. This accomplishes the desirable result of minimal two sidedness and immediate high pigment retention.

Referring now to the drawings in detail wherein like reference characters indicate like parts throughout the several figures, the reference numeral 1 indicates a filler storage tank in a paper making system in which an aqueous slurry of paper filler is stored. A slurry feed line 2 extends from the tank 1 through a valve 3 to a spray feed pump 4. Filler slurry is pumped by the spray feed pump 4 through its discharge feed line 5 into a screen strainer 6. The outlet from the screen strainer 6 is controlled by a valve 7 and the filler slurry passes from the valve 7 through a line 8 to a concentric reducer 9. A horizontal spray distribution pipe 10 is positioned above the wire of a paper making machine and extends perpendicular to the direction of travel of the wire in the machine.

The spray distribution pipe 10 has a pressure gauge 11 mounted thereon and is further provided with a plurality of depending spray nozzles 12 communicating therewith. An eccentric reducer 13 is secured to the end of the pipe 10 opposite the concentric reducer 9 and has a recycle line 14 extending therefrom to a throttle valve 15. A drain hose 16 extends from the throttle valve 15 and is arranged to discharge into the tank 1 or selectively into the sewer. A flush Water line 17 extends from a source of water under pressure through a valve 18 into the line 2 between the valve 3 and the pump 4. Flushing water provided through the flush Water line 17 is used when the paper making run has been completed and it is necessary to flush the filler slurry from the lines.

As can be seen clearly in FIGURE 2, the filler slurry spray from the spray nozzles 12 is directed at the moving web 20 from a distance of from 6 inches to 4 feet above the web 20 depending upon the speed of the wire 21 and the pressure of spray. The spray can be a hollow cone as is shown in FIGURE 1 at 19 and is representative of the type of spray pattern which is obtained when using low pressures of about 3 to 20 p.s.i.g. The spray nozzles 12 are spaced apart on the spray distribution pipe 10 such that the sprays from each of the nozzles 12 intersect adjacent sprays to form the spray pattern 3 19 which can be described as a first series of circles in tangential relationship upon which a second series of tangential circles of the same size are superimposed with the centers of these circles at the point of tangency of the circles in the first series.

The spray nozzles 12 are arranged so that they extend completely across the width of the wire 21.. The spray is directed to the web 20. as shown in FIGURE 2 at a point from 3 to 12 feet upstream from the first vacuum box 22. On conventionally used machines this is usually the fourth to sixteenth table roll 23 depending on the speed of the wire 21 as Well as the point at which the web consistency is such that optimum filler retention and optical proper-ties are obtained. in the paper.

By means of this process the filler strikes and is drawn into the web where it contacts the fibers and fibrils of the paper and becomes attached thereto by physical and/or chemical means.

The filler particles used in this invention are much smaller in size than the space between the paper fibers and would normally be expected to be drawn completely through the web by a process such as that contemplated by the present invention. Since this does not occur when following the process as described it is theorized that a surface attraction between the filler and cellulosic fibers and fibrils occurs. I

To avoid extreme two sidedness and excess filler losses it is necessary that the filler contact the web when the solids content of the web is such that the filler is able to be drawn into it by suction and be evenly distributed. If the filler contacts the web too near the headbox, it is drawn completely through the web with large filler losses. If the filler is sprayed onto the web too far downstream, the web is too dry and the filler only coats the top surface of the web. Some of this filler from the top surface is lost due to dusting after the paper has dried.

At spray heights of from 6 inches to 4 feet and spray pressures of from 3 p.s.i.g. to 20 p.s.i.g. good results are obtained at from 3 to 12 feet upstream from the first vacuum box. The concentration of the filler slurry should be such that it can be atomized by the spray nozzle. The mos-t effective filler concentrations are from 0.5 lb./gal. to 2 lbs./ gal. or about to 20% solids. The speed of the wire determines the specific heights and spray pressures of the nozzles as well as their location. Within the limits defined, machine speeds of from 1000 to 3000 feet per minute are operable.

The pigment fillers useful in this process are inorganic siliceous pigments of fine particle size, usually within the 0.01 to 0.6 micron range. The siliceous pigments with silanol groups on the surface thereof are those most advantageously used since they have a tendency to attach chemically as well as physically to the cellulosic fibers, assuring even distribution throughout the paper with high retention.

These pigments can be characterized as those amorphous siliceous pigments containing at least 50% SiO and at least 3.5% bound water. They can be made by precipitating Si0 from sodium silicate by means of acids or in the' manner described in US. Patents 3,034,913 and 3,034,914 wherein sodium silicate is partially neutralized with acid and silica is thereafter precipitated therefrom with an acid salt such as calcium chloride or alum.

Other suitable siliceous fillers are made by precipitating silica from calcium silicate with acid in the the manner described in US. Patent 3,110,606.

Another suitable siliceous filler is calcium silicate prepared by a hydrothermal pressure reaction of lime and Other conventionally used fillers for newsprint and other. lightweight papers can be used in this invention; for ex-.

ample clay or calcium carbonate. Combinations of siliceous fillers are also suitable, for example, mixtures of silica and sodium alumino silicate.

The pH of the reaction medium,,as well as the pre-. cipitating pH, and the type of silicate used are among the factors which determine the specific sodium alumino silicate produced. A variation in these factors determines.

the molar ratios of the oxides of sodium, aluminum,

and silicon, as well as the particle size, specific gravity,

and surface area of the pigment. Pigments with molar ratios of above 0.8 mole of Na O per mole of A1 03 and 1 over 4 moles of Si0 per mole of Na O with a particle size of less than 0.14 micron in diameter, a specific'gravity I v of 2.10 to 2.26 and a surface area greater than 20 square meters per gram are useful in the practice of this invention.

The following examples and tables illustrate the prac:

tice of this invention and are not intended to limit the invention.

Example 1 A Fourdrinier paper machine with a speed of 2,000

ment was sprayed on the moving web at a pressure of 7 Sufficient pigment was One point of application was at the first fiatbox. A second point was at the sixth table roll and the third point was at the 16th table roll. The results are shown in Table I.

ExampleZ Using the same speed machine sodium alumino silicate filler was applied under 10 p.s.i.g. at the first table roll and under 15 p.s.i.g. at the 2nd, 4th, 6th, and 12th table rolls. The results are shown in Table II.

Example 3 spray was 18 inches. applied was varied on the different runs. It was applied at the 4th, 6th and 8th table rolls during successive runs. The results are in Table III.

TABLE I.-32-LB. STANDARD NEWSPRINT Percent Laroc ue Percent Polnt Applied Pressure, Percent Percent Percent smoothness, Brightness, Percent Strike Through, Printap.s.i.g. Applied Retained Retention W/F W/F Opacity at 2.0 gJm. ink bility pick up Unfilled- /92 58. 2/58. 0 90. 7 12 1st flatbox. 7 3. 26 1. 88 57. 7 61. 0/58. 5 91. 5 9. 7 S 6th table roll 7 3. 26 2. 52 77. 2 92/85 61. 6/59. 4 92. 8 8. 5 84. 5 16th table roll 7 3. 26 3. 15 96. 6 87/79 62. 5/59. 6 92. 9 7. 7 84. 3

TABLE lI.33-LB. OFFSET NEWSPRINT Pressure, Percent Percent Percent Brightness, Percent Percent Percent Point Applied p.s.i.g. Applied Retained Retention W/F Opacity Larocque Printability Strike Through U fi 58/58. 3 90. 5 12. 84. 1st table roll. 2. 38 2. 30 96. 5 61. 8/59. 1 92. 3 9. 8 85. 0 2nd table roll 3. 08 2. 39 77. 5 62. 0/59. 4 92. 1 8. 6 84. 5 4th table roll 15 3. 08 3. 03 98. 5 62. 2/59. 2 91. 8 9. 0 84. 2 6th table roll 15 3. 08 2. 74 89. 0 61. 9/59. 2 92. 0 9. 8 84. 7 12th table roll.. 15 3. 08 2. 22 72. 2 62/59. 5 91. 6 8. 5 84. 5

The data in Tables I and 11 indicate that when the filler pigments are sprayed onto the moving web, they effectively fill the paper and the optimum positions for spraying 3 p.s.i.g. to about p.s.i.g. from spray nozzles positioned above the moving web and intermediate the headbox and the first vacuum box of the papermaking machine wherein on the machines used is from the sixth to the sixteenth 15 the solids content of the moving web is such that the filler table roll for Example 1 and at the fourth to the sixth is uniformly drawn substantially completely therethrough table roll for Example 2. It is possible to determine the and is substantially completely retained therein, thereby optimum point of contact for any machine used in a distributing said filler pigment uniformly throughout said similar manner. moving web.

TABLE III Percent Larce- Percent Percent Percent que Strike ANPA Print- Point Applied Percent Ash Loading Brightness, Opacity Mullen, p.s.i. Through at ability, W/F

WI]? 2.0 Jm. Ink Pick Up, W/F

o. 52 57. 5/ s. 0 90. 5 6. 2 13. 0/11. 0 85. 7/84. 5 2. 4s 2. 10 60. 1/ 9. 1 93. 3 7. 1 9. 1 7. 5 85. 5/84. 5 3. 06 2.78 60. 5/59. 5 93. 0 6. 3 9. 2/7. 4 85. 1/84. s 8th table roll 2. 4o 2. 05 59. 1/59. 0 92. 9 s. 6 10. 5/7. 5 85. 5134. 3 Internally Filled (Headbox) 2.50 2. 11 59. 0/59. 4 91. 5 7. 2 8.7/7.0 85. 0/84. 2

The data indicates that beneficial properties are imparted to the paper when the filler pigment is sprayed on the moving web. With the machine used as shown in Example 3, the data indicates that the point of optimum results is at or near the 6th table roll which is about 6 to 7 feet upstream from the first vacuum box. The data illustrates the fact that the optical properties of internally filled paper are somewhat less than the paper filled by the process of this invention while the print properties are equivalent.

The examples indicate the feasibility of the process and the data indicates the beneficial results imparted to the paper in terms of brightness, opacity and printability as well as pigment retention. Since it is obvious that the invention can be practiced on equivalent machines and under different conditions it is not intended that it be limited by the examples but only by the scope of the appended claims.

I claim:

1. A method of distributing siliceous filler pigments of a particle size of from 0.01 to 0.6 micron substantially uniformly throughout a moving web on a Fourdrinier papermaking machine which consists essentially of spraying an aqueous slurry of said filler pigments to said moving 55 web from a height of from about 6 inches to about 4 feet above the moving web at a spray pressure of from about 2. The method of claim 1 wherein said spray is directed toward the moving web from a series of sprays essentially perpendicular to the direction of travel of the web at least about 3 feet upstream from the first vacuum box on the papermaking machine, and wherein the spray pattern is a hollow cone pattern.

3. The method of claim 1 wherein the speed of the moving web is about from 1000 feet per minute to about 3000 feet per minute.

References Cited by the Examiner UNITED STATES PATENTS 2,054,630 9/ 1936 Hurrey 162186 X 2,062,563 12/1936 Fair 162-186 2,112,540 3/ 1938 McAndrews et a1. 162186 2,373,914 4/1945 Quinn 162-l86 X 2,426,043 8/ 1947 Muggleton 162186 2,943,970 7/1960 Allen 162-181 3,034,913 5/ 1962 Lagerstrom 162181 FOREIGN PATENTS 720,006 12/1954 Great Britain.

DONALL H. SYLVESTER, Primary Examiner, EO A HO E. E mi r.

Claims (1)

1. A METHOD OF DISTRIBUTING SILICEOUS FILLER PIGMENTS OF A PARTICLE SIZE OF FROM 0.01 TO 0.6 MICRON SUBSTANTIALLY UNIFORMLY THROUGHTOUT A MOVING WEB ON A FOURDRINIER PAPERMAKING MACHING WHICH CONSISTS ESSENTIALLY OF SPRAYING AN AQUEOUS SLURRY OF SAID FILLER PIGMENTS TO SAID MOVING WEB FROM A HEIGHT OF FROM ABOUT 6 INCHES TO ABOUT 4 FEET ABOVE THE MOVING WEB AT A SPRAY PRESSURE OF FROM ABOUT 3 P.S.I.G. TO ABOUT 20 P.S.I.G. FROM SPARY PRESSURE OF FROM ABOUT ABOVE THE MOVING WEB AND INTERMEDIATE THE HEADBOX AND THE FIRST VACUUM BOX OF THE PAPERMAKING MACHINE WHEREIN THE SOLIDS CONTENT OF THE MOVING WEB IS SUCH THAT THE FILLER IS UNIFORMLY DRAWN SUBSTANTIALLY COMPLETELY THERETHROUGH AND IS SUBSTANTIALLY COMPLETELY RETAINED THEREIN, THEREBY DISTRIBUTING SAID FILLER PIGMENT UNIFORMLY THROUGHOUT SAID MOVING WEB.

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