US 3895164 A
A process for imparting friction properties to a base material such as paper, and the resultant product, wherein the base material has applied to its surface a mixed alumina compositions comprising positively charged colloidal aqueous dispersions whose solids content comprises 25 to 75% of a first alumina component having an ultimate dispersed particle size no more than about one-fifth as great as a second alumina composition comprising 75 - 25% of the solids content.
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Description (OCR text may contain errors)
United States Patent [1 1 Carstens et a1.
1 1 PROCESS FOR IMPARTING FRICTION PROPERTIES TO A BASE MATERIAL AND THE RESULTANT PRODUCT  Inventors: Ronald A. Carstens, Anacortes; William .I. Butcher, Vancouver,
both of Wash.
 Assignee: Key Chemicals, lnc., Anacortes,
 Filed: Dec. 19, 1973 211 Appl. No; 426,219
Related U.S. Application Data  Division of Ser. No. 201,899, Nov, 24, 1971, Pat.
 U.S. Cl 428/329; 427/372  Int. Cl. B44d 5/08; D21h 1/16  Field of Search 117/127, 130 R, 139.5 CF, 117/169,126 OF, 126 GM,152,138.8 R; 252/313 R, 317; 162/181  References Cited UNlTED STATES PATENTS 2,734,835 2/1956 Florio et a1. 1. 117/1395 CF July 15, 1975 2,786,787 3/1957 Flon'o 117/169 2,909,451 10/1959 Lawler et a1. 117/1395 CF 2,931,779 4/1960 White 252/313 R 3,013,903 12/1961 Bugosh 117/169 R 3,219,479 11/1965 Le Clercq 117/169 R Primary Examiner-William D. Martin Assistant Examiner-Sadie L. Childs Attorney, Agent, or FirmHolman 8L Stern  ABSTRACT 2 Claims, 2 Drawing Figures 1 PROCESS FOR IMPAR'ITNG FRICTION PROPERTIES TO A BASE MATERIAL AND THE RESULTANT PRODUCT This is a divisional of application Ser. No. l,899, filed Nov. 24, l97l, now US. Pat. No. 3,8l2,055, issued May 2l, I974.
BACKGROUND OF THE INVENTION l. Field of the Invention:
This invention relates to mixed alumina compositions. More particularly, this invention relates to mixed alumina compositions of different particle sizes and to their use in paper manufacturing.
2. Description of the Prior Art:
Methods for economically controlling pitch in paper mill systems have been intensely studied for many years. While only a small portion of available pitch actually recirculates in the white water, this is often present in amounts great enough to agglomerate at various locations, necessitating frequent shutdowns for cleaning purposes. Dispersants alone are generally ineffective for this purpose, since they merely function to keep the ptich in suspension while its concentration builds By maintaining the concentration of pitch in the white water below critical levels, the formation of deposits can be substantially reduced. The addition of flocculating agents such as talc, diatomaceous earth and the like has met with limited success, since the excessive use of such materials tends to weaken and discolor the sheet.
Recently several investigators have reported on the use of colloidal aluminas as paper pitch control agents. While offering significant advantages over other methods, the cost effectiveness of these materials has not been sufficient to induce widespread acceptance in the industry.
In addition to their use as pitch control agents, colloidal aluminas have been used as anti-slip agents for frictionizing paper surfaces. Due to the positive electostatic charge of colloidal aluminas, they are strongly attracted to negatively charged surfaces such as pitch particles and paper surfaces. Since the aluminas are water compatible, handling and cleanup problems encountered with silicate colloids are minimized.
In dealing with non-skid paper surfaces, the friction properties of the surface are commonly measured by determining the slip angle, a measure of the angle at which two contacting non-skid surfaces will begin to slide under controlled conditions. Differences of only a few degrees or so, as determined by accurate testing, may have significant effects on the ultimate suitability of the papers for various applications.
SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide a composition and method for controlling pitch in paper mills.
Another object of this invention is to provide a composition and method for imparting anti-slip properties to smooth surfaces.
A further object of this invention is to provide a composition of mixed aluminas having a higher electrostatic charge than either component alone.
An additional object of this invention is to provide a composition of mixed aluminas having synergistic properties as compared to the individual components.
Other additional uses such as for paper mill retention aids and anti-static agents for rugs or similar surfaces will be obvious to those skilled in the art.
Briefly, these and other objects, features, and advantages of the present invention are provided by mixed alumina compositions comprising positively charged colloidal aqueous dispersions whose solids content comprises 25 of a first alumina composition having an ultimate dispersed particle size no more than about one-fifth as great as a second alumina composition forming the remainder of the solids content. The dispersions preferably contain 1 to 15% solids content and have a pH of 0 to 6. These compositions have par ticular utility in controlling paper mill pitch, and in providing anti-slip properties to smooth surfaces such as highly calendered paper surfaces.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 graphically illustrates the slip angles realized by using an anti-slip agent comprising a mixture of aluminas of generally the same ultimate dispersed particle sizes; and
FIG. 2 illustrates the slip angles realized by using an anti-slip agent comprising a mixture of aluminas of significantly different ultimate dispersed particles sizes according to this invention.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS In accordance with the present invention, the preferred mixtures comprise about 25 757r ofa first alumina composition having a particle size of about 4 6 mp, a surface area of about 300 m /gm, and a purity of at least about 99% dry weight alpha alumina with a second alumina composition having a particle size of about 20 3O mu, a surface area of about I00 m /gm, and a purity of at least about 97% dry weight alumina. The ultimate dispersion is prepared by adding I to 15%, preferably 3 to 6% and especially about 4%, of the alumina mixture to an acidified aqueous system having a pH of O to 6, preferably 3 to 4.
Conventional additives such as anti-foam agents, cationic or non-ionic surfactants, corrosion inhibitors, freeze-thaw stabilizers, and the like may be added in customary proportions. Since the aqueous colloidal dispersion carries a positive charge, the use of anionic surfactants or other additives is generally to be avoided because such additives tend to result in poor or broken emulsions.
The critical feature of the instant invention resides in the mixture of aluminas having vastly different ultimate dispersed particle sizes, that is, at least one of the aluminas having an ultimate dispersed particle size no more than about one-fifth of the other, with about a 25 75% ratio of the first in the mixture. The individual particle sizes, specific surface areas, purities, percent total solids content in the dispersion, and pH of the dispersion as discussed above and hereinafter provide optimum properties, but as will be seen from the attached graphs, it is the use of a mixed particle size that provides unexpected results.
In FIG. 1 the solid lines graphically illustrate the straight-line average slip angle in degrees to be anticipated from a mixture of two materials having generally the same ultimate particle sizes while the broken lines illustrate the actual average slip angles in degrees obtained from such mixtures. It will be seen that, in every instance, the mixed compositions provide a result sub stantially below that to be anticipated.
In contrast, by reference to FIG. 2 it will be seen that by mixing aluminas having substantially different ultimate dispersed particle sizes, on the order of 5:1, the resultant anti-slip agent, for the most part, provides average slip angles substantially above that to be anticipated. Such a phenomenon is quite unexpected.
Again, while the specific materials described below are not to be limiting on the instant inventive concept, the following properties are set forth as preferred.
Alpha alumina compositions are preferably used as the first alumina component of the present invention and such materials are commercially available. For example, the material identified as DISPAL M is quite satisfactory. Preferably the first alumina has an ultimate dispersed particle size (the particle sizes are always referred to herein in a dispersion since upon drying these materials tend to agglomerate) of 2 to mp diameter, preferably about 4 to 6 mp.
The second alumina component of the present invention may be of any form but preferably is of other than the alpha form. Particularly suitable are gamma and delta fumed aluminas. Commercially available materials identified as ALON C and Aluminium oxide C are quite suitable, the ALON C providing even better slip angles as seen in FIG. Particle sizes of 10 to 100 mp. diameter, preferably of to mu, are preferred.
The two aluminas are admixed in a ratio of 25 to 75% by weight of the first alumina with correspondingly 75 to 25% by weight of the second alumina. Optimal proportions can readily be determined for particular application, but will generally contain from to 65% by weight of each alumina. Particularly good results for many applications are obtained with 5O mixtures.
of 2 to 6, preferably 3 to 4, and agitated. Suitable acids include hydrochloric acid, acetic acid, monochloroacetic acid, nitric acid, hydroxyacetic acid, sulfamic acid and the like; halogenated acids are preferred as they tend to result in more stable dispersions. Concentrated stock dispersions may be diluted with water or acidified water for subsequent use.
The dispersions of the present invention have a positive electrostatic charge much stronger than that of dispersions prepared with either component alone. Thus, they are particularly useful in a wide variety of electrostatic charge neutralization techniques used to treat negatively charged materials such as pitch in pulp and paper mills, latex, gums, primary and secondary sewage, and the like. As little as about .03 to .3 lb of alumina per ton of stock is generally effective, preferably at a pH of about 3 to 6.
The compositions of the present invention are useful in imparting anti-slip friction surfaces to material such as papers, particularly highly calendered papers, but including coated and impregnated papers, fiber glass, textiles, some plastics and metals. Dispersions of about 0.8 to 8% by weight can be applied to such surfaces by spray, roller, or sponge coating techniques known in the art, although a preferred method and apparatus for using these materials will be discussed hereinafter with respect to Example 4 and Table 5.
Having now generally described the invention, it is believed that those skilled in the art can utilize it to its fullest extent. The following Examples are accordingly presented as illustrative and not limiting of the remainder of the disclosure.
Table 1 sets forth physical characteristics of the alumina compositions used in the following Examples, together with characteristics of a fumed silica composi tion used as a comparison.
with acid added The greater electrostatic charge and resistant to slip resulting from the admixture of small and large alumina particles will necessarily be somewhat different for different ratios and the optimum effect will have to be determined for each application. Close packing or loose packing of such minute particles of greatly varying shapes may result in varying resistance to slip and electrostatic charge.
The colloidal aqueous dispersions of the present invention are prepared by standard methods, generally to a stock mixture having a high solids content of about ID to 40% by weight which may be diluted with water to a solids content of about I to 15% by weight, preferably about 4 to 9% for subsequent use or the alumina powders may be added to acidified water having a pH Slip angles were determined after non-skid application by the modified Meyer 16 method. The board to be treated is cut into 4 inch wide strips approximately 3 feet long and placed in an oven and pre-heated to about F. to simulate corrugator plant conditions. A 4 inches three-fourth inch X three-fourth inch cellulose sponge is soaked in a 10/1 dilution of solution and then when saturated it is squeezed around in a U shape until the excess liquid runs out. The board is then taken out of the oven, laid flat on a table and held firmly in place by clamps. The wet sponge is placed on the bottom of the board in front of an 8/10 mil Meyer Rod along with a piece of wood to push the sponge into the rod. The board is then coated by running the Meyer Rod and sponge up the board in one quick motion.
while squeezing the sponge so that the nip between the Meyer Rod and board is always flooded. The board is then held upside down to drain any excess liquid, and
TABLE 3 Continued PROPORTION OF INGREDIENTS AVG. SLIP ANGLE let dry in the air. In this manner a very dilute solution DEGREES of non-skid is applied very evenly and uniform slip 5 I FIGURE ZCURVEC angle results are obtained by a Key slip angle tester. Alumoma A gg B i 40 O 25 75 3910 EXAMPLE I 50 50 393 7 8.9 Comparative tests of pitch neutralization were perg 3- formed by standard method on representative individ- RE 2 CURvE D Alumina A Alumina C ual alumina compositions and mixtures thereof accord- 0 100 35,5 ing to the present invention. ml samples of a 0.1% 75 37.2 pitch dispersion taken from a paper mill were treated with varying volumes of l% alumina solids dispersions lot) 0 37.1 to Hot: the pitch, the resulting mixtures filtered, and the filtrate examined visually for clarity. A clear filtrate indicates complete neutralization of the pitch particles EXAMPLE 3 and resulting floc formation which is filtered out. Re- Using the following formulation, slip angle tests were sults are presented in Table 2. 20 conducted as described above on board and paper TABLE 2 FILTRATE APPEARANCE cc of l% Alumina Solids Alumina A Alumina 8" 37.5% A per 20 cc. l% Pitch 62.5% "3 Dispersion like pretty cloudy clear clear 5cc pretty cloudy v. slightly clear cloudy 2cc pretty cloudy fairly cloudy clear lcc very cloudy fairly cloudy slightly cloudy Expected Neutral Point 10cc lOcc 2cc The above results indicate that alumina mixtures of coated with various dilutions of the basic formulation the present invention have a much higher electrostatic in actual plant tests. charge than either of the component materials alone, COMPOSITION since only 20% as much of the mixture was required to reach an end point, as compared to the most effective Alumina A 5 WW Individual component. Alumina B 3 Wm Monochloroacetic Acid .5 wt% Corrosion inhibitor .1 wt% EXAMPLE 2 IPA (for freeze-thaw 3 M54 stability) This Example illustrates the mproved slip angles ob Dcfuamcr l W talned on corrugated paper using the compositions of w Balance the present invention. All slip angles were measured at sliding pressures of 69 gm/sq in. using the Meyer 16 method to apply the composition, and represent an av- I Typlcal P angles Obtained the above p erage of at East Six applications A" dispersions had a tron from actual corrugatmg plant results are shown in total solids content of 3.92 weight Results are sum- Table marized in Table 3 and graphically illustrated in the TABLE 4 FIGURES.
It can be seen from the following data that improved Pilution Shipping Cartons Bags slip angles are obtained only by mixtures of different Pmed aluminas having the necessary properties such as parti- As is 37 4o 35-40 3940 3740 cle sizes and surface areas as described herein. M 3740 3540:
l13 3540 343 8 TABLE 3 I26 32-37 30-36 l: l() 3034 2832 PROPORTION OF INGREDIENTS AVG. SLIP ANGLE DEGREES 6 A] FIGURE l CURVE A 0 EXAMPLE 4 gg B D 400 Using a l.4 aqueous dilution of the composition of 75 25 38:0 Example 3, 50 lb Kraft liner board was coated using the g2 method described in our copending US. Pat. applica- 0 100 m tion Ser. No. 20| ,900 and now U.S. Pat. No. Alumina B QP CURVE 3 3,812,055, filed of even date with this application and 0 35.5 entitled Method and Apparatus Anti-Slip Applying 25 Anti-sli A ents, the disclosure of which is incor o- 50 so u, i p g 75 25 rated by reference. Briefly, the technique described I00 0 40.0 therein involves spraying onto an applicator roller at an 7 8 angle of 90 to 270 from the nip at the top, and passing alumina composition having an ultimate dispersed the board over the top thereof to apply an even film of articl size no more than about one-fifth as great anti-slip agent to the board. By spraying onto a roller as a s cond alumina composition; and away from the nip, much better results are obtained b. correspondingly 75-25% by weight of said second than by spraying directly into the nip. Table illus- 5 l mina m sition, said second alumina compotrates results obtained by this method. sition having a particle size of about lO-IOO mu.
TABLE 5 Run Spray Angle Top Roller Board Speed Spray Pressure Slip Angle l 270' up 450fpm 30psi 35.5 2 270 down 400fpm 37psi 375 3 270 down 540fpm 30psi 375 4 90 down 450fpm 30psi 37.0 5 into nip down 400fpm 30psi 33.0"
It will be appreciated that while the foregoing Examand drying the coated base. ples are directed to preferred embodiments of this in- 2 P r h vi a Surface coating gompfising a ivention, it is capable of numerous alterations or modifitively charged colloidal mixed alumina comprising: cations as will be apparent to those skilled in the art. a. -75% by weight of the total alumina of a first What is claimed is: alumina composition having an ultimate dispersed l. A process for imparting friction properties to a particle size no more than about one-fifth as great base material which comprises applying to the surface as a second alumina composition; and of said material a positively charged colloidal aqueous b. correspondingly 75-25% by weight of said second dispersion having solid content of l to 15% of mixed 25 alumina composition, said second alumina compoalumina comprising: sition having a particle size of about l0-l00 my a. 25-75% by weight of the total alumina of a first