WO1999039838A1

WO1999039838A1 - A method for enhancing with latex the anti-skid properties of paper

Info

Publication number: WO1999039838A1
Application number: PCT/US1998/002371
Authority: WO
Inventors: Jorge F. Miranda; Eric Tillirson
Original assignee: Vinings Industries, Inc.
Priority date: 1998-02-10
Filing date: 1998-02-10
Publication date: 1999-08-12
Also published as: CA2320321A1

Abstract

The invention relates to a method for enhancing the anti-skid properties of a paper product by contacting the paper product with an aqueous composition comprising a colloidal silica; a latex; and an alcohol. The invention further relates to the products produced by the present invention. The invention further relates to an aqueous composition for enhancing the anti-skid properties of a paper product.

Description

A METHOD FOR ENHANCING WITH LATEX THE ANTI SKID PROPERTIES

OF PAPER

FIELD OF THE INVENTION

The present invention relates to a method and composition for enhancing with latex the anti-skid properties of paper.

BACKGROUND OF THE INVENTION

Certain compounds present in wood have a deleterious effect on the anti-skid or friction properties of paper. Resinous and fatty acids such as oleic, linoleic, linolenic, palmitic and/or stearic acid are liberated from wood species during the pulping process. Due to their relatively low surface energies, these materials reduce the anti-skid or friction properties of paper.

The need for enhanced anti-skid or friction properties of paper products is based on handling requirements of the paper reels in the paper mill as well as functional performance of the paper product. Paper products with reduced anti-skid or friction properties experience reel telescoping issues in the mill, which makes it difficult to transport finished rolls of paper in the mill. Another issue is crepe wrinkles, where the sheet will slip upon itself after having been wound into a tight reel. As the sheet slips, ridges or wrinkles form in the paper web. Once wrinkled, the paper web is unsuitable for printing and converting into the end product. A paper product with diminished anti-skid properties also exhibits slipperiness in the converting process by misregistering on the printing papers press and running ahead during printing papers press stops or slow downs. The run ahead in the pressroom can result in damage to the print plates as well as break out on the printing papers press. Colloidal silica has been used for many years in the art to increase the anti-skid properties of paper products. The prior art discloses the coating of the surface of a paper sheet with colloidal silica to enhance sheet friction. U.S. Patent No. 2,872,094 to Leptien; U.S. Patent Nos. 4,452,723 and 4,418,111 to Carstens; U.S. Patent No. 3,916,058 to Vossos; U.S. Patent Nos. 3,901,987; 3,754,984 and 3,860,431 to Payne et al; U.S. Patent No. 5,466,493 to Mefford et al; U.S. Patent No. 5,569,318 to Jarrand; and Japanese Patent Application No. 05172989 to Yoshihiko et al. disclose the coating of a paper product with silica in order to enhance anti-skid properties.

There are some problems associated with the surface application of colloidal silica to paper. Silica deposits often occur in undesirable places such as in the application equipment. Moreover, stripping problems are often observed in the finished paper. In the case of spraying applications, the narrow tips can easily get plugged, causing disruption or interruption of the spraying pattern or over-spraying of certain areas. In many cases a significant loss of friction is observed between the reel and the rewinder.

In an attempt to overcome these application problems, the prior art discloses the combination of a glycol with colloidal silica. U.S. Patent No. 5,569,318 to Jarrand; U.S. Patent No.5,466,493 to Mefford et al; and U.S. Patent Nos. 3,860,431 and 3,901,987 to Payne et al. disclose the application of a composition composed of silica and a glycol on the surface of paper in order to increase the anti-skid or friction properties of paper. These references, however, do not teach one of ordinary skill in the art to use a latex in combination with colloidal silica and an alcohol to enhance the anti-skid properties of paper.

The use of a latex in the treatment of paper is also disclosed in the art. U.S. Patent No. 4,258,104 to Lee βt al. and U.S. Patent No. 5,460,874 to Rao disclose the application of a composition composed of a latex on the surface of paper in order to enhance or increase the printability properties of paper. These references, however, do not disclose the use of the latex in combination with colloidal silica and an alcohol in order to enhance the anti-skid or friction properties of paper. Moreover, the prior art does not teach the use of a latex to increase the anti-skid or friction properties of paper.

U.S. Patent No. 5,244,728 to Bowman et al. and U.S. Patent No. 5,275,846 to Imai et al. disclose compositions composed of silica and latex. These compositions are applied to the surface of paper in order to enhance the printability or print retaining layer of the paper. These references do not disclose the use of an alcohol in the coating composition. Moreover, these references do not teach the application of a composition composed of latex and colloidal silica in order to enhance the anti-skid or friction properties of paper.

U.S. Patent No. 4,094,685 to Lester et al. discloses an expandable coating. The composition is composed of a binder polymer latex, a dispersing agent, polyspheres, a defoamer, a bridge solvent, and a thickener. There is no disclosure in Lester et al. for coating paper to enhance the anti-skid properties of paper. The composition of Lester et al. is used in textiles and paints and not paper products.

U.S. Patent No. 4,980,024 to Payne et al. discloses a method for improving the anti-skid properties of paper by spraying the paper with a composition composed of an acrylamide, glycerine, and an aqueous silica sol. The acrylamide used in Payne et al. is water-soluble and, consequently, not a latex of the present invention.

In light of the above, it would be very desirable to have a method for enhancing the anti-skid properties of paper. In addition, it would be advantageous to maintain or increase other properties of paper such as printability and sizing. Finally, there is a need for enhancing the properties of paper in the absence of application problems. The present invention solves such a need in the art while providing surprising advantages. SUMMARY OF THE INVENTION

In accordance with the purpose(s) of this invention, as embodied and broadly described herein, this invention, in one aspect, relates to a method for enhancing the anti- skid properties of a paper product, comprising contacting the paper product with an aqueous composition, comprising:

(a) a colloidal silica;

(b) a latex; and

(c) an alcohol.

The invention further relates to a method for enhancing the anti-skid properties of a paper product, comprising contacting the paper product with an aqueous composition, consisting essentially of:

(a) a colloidal silica;

(b) a latex; and

(c) an alcohol.

The invention further relates to the products produced by the present invention.

The invention further relates to an aqueous composition for enhancing the anti-skid properties of a paper product, consisting essentially of:

(a) a colloidal silica;

(b) a latex; and (c) an alcohol.

The invention further relates to an aqueous composition for enhancing the anti-skid properties of a paper product, comprising:

(a) a colloidal silica;

(b) a latex; and

(c) an alcohol,

wherein the composition does not include a polysphere.

(a) a colloidal silica;

(b) a latex; and

(c) an alcohol comprising a compound having the structure H[OCH₂CH₂]_mOH, wherein m is an integer of from 2 to 14; a compound having the structure H[OCH(CH₃)(H)CH]_nOH, wherein n is an integer of from 1 to 10; a compound having the structure HOCH₂(CHOH)_pCH₂OH, wherein p is an integer of from 1 to 4; or a combination thereof.

The invention further relates to an article comprising a paper product coated with colloidal silica, a latex, and an alcohol.

Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

DETAILED DESCRIPTION OF THE INVENTION

The present invention may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and the Examples included therein.

Before the present methods and products are disclosed and described, it is to be understood that this invention is not limited to specific synthetic methods or to particular formulations, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings:

The singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise.

"Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

The term "enhance" is defined as an increase in a desired effect and/or an increase in the duration of the desired effect. The term "paper product" is defined as any manufactured paper that is prepared from a paper making process. Paper pulp is not a paper product of the present invention.

In accordance with the purpose(s) of this invention, as embodied and broadly described herein, this invention, in one aspect, relates to a method for enhancing the antiskid properties of a paper product, comprising contacting the paper product with an aqueous composition, comprising:

(a) a colloidal silica;

(b) a latex; and

(c) an alcohol.

(a) a colloidal silica;

(b) a latex; and

(c) an alcohol.

(a) a colloidal silica; (b) a latex; and

(c) an alcohol.

(a) a colloidal silica;

(b) a latex; and

(c) an alcohol,

wherein the composition does not include a polysphere.

(a) a colloidal silica;

(b) a latex; and

The invention further relates to an article comprising a paper product coated with colloidal silica, a latex, and an alcohol. Any colloidal silica known in the art is useful in the present invention. In one embodiment, the colloidal silica is anionic. Examples of silica compounds useful in the present invention are those disclosed in but not limited to The Chemistry of Silica by Ralph K. Her (John Wiley & Sons, 1979). The size and shape of the colloidal silica can vary depending upon the type of silica used. In one embodiment, the colloidal silica has a particle size of from 5 to 160 nm, preferably from 7 to 150 nm. In another embodiment, the colloidal silica has a particle size of from 60 to 90 nm. In another embodiment, the colloidal silica has a particle size of from 7 to 30 nm. In another embodiment, the colloidal silica is a mixture of colloidal silica having a particle size of from 60 to 90 nm and of from 7 to 30 nm. The amount of colloidal silica used in the present invention can also vary. In one embodiment, the amount of colloidal silica is from 0.5 to 50 %, preferably from 10 to 45 % by weight of the aqueous composition. In another embodiment, the colloidal silica can be used as a sol produced by any technique known in the art.

The colloidal silica used in the present invention can also be modified with aluminum. In one embodiment, aluminum ions can be incoφorated on the surface of the colloidal silica. The aluminate-modified silicas disclosed in The Chemistry of Silica by Ralph K. Her (John Wiley & Sons, 1979) and U.S. Patent No. 2,892,797 to Alexander et al. , which are herein incorporated by this reference, can be used in the present invention. An example of an aluminate-modified silica useful in the present invention includes, but is not limited to, LUDOX TAM^® or LUDOX AM^®, which is manufactured by DuPont, Wilmington, Delaware, U.S.A.

In another embodiment, a metal oxide can be used in combination with the colloidal silica. In one embodiment, the metal oxide is alumina. When the metal oxide is used in the aqueous composition, the metal oxide and colloidal silica are from 3 to 50 %, preferably from 5 to 35 % by weight of the aqueous composition.

Latexes used in the present invention enhance the anti-skid or friction properties of paper. The term "latex" is defined as a water-insoluble polymer composition, typically a colloidal suspension, capable of forming a film on the surface of a paper product. The latex used in the present invention can be any synthetic or natural latex.

Any latex used in the prior art for paper coating can be used in the present invention. In one embodiment, the latex is a styrene butadiene rubber, a vinyl acetate homopolymer, a vinyl acrylic copolymer, an acrylic polymer, a styrene-acrylic polymer, or a combination thereof. The molecular weight of the latex can vary depending upon the polymer selected. In one embodiment, the latex is a styrene-acrylic resin. In another embodiment, the latex is a styrene-acrylic resin comprising 2-ethylhexyl acrylate as a monomeric residue.

Examples of vinyl acetate homopolymers include, but are not limited to, POLYCO 2149 AD^® and POLYCO 2152^®, which are manufactured by Rohm and Haas, Philadelphia, PA, U.S.A. Examples of vinyl acrylic copolymers include, but are not limited to,

POLYCO 3220^®, POLYCO 3103^®, POLYCO 6108^®, and POLYCO 3250^®, which are manufactured by Rohm and Haas, Philadelphia, PA, U.S.A. Examples of styrene-acrylic resins include, but are not limited to, RHOPLEX B-15P^®, RHOPLEX P-554^®, RHOPLEX B-60A^®, and RHOPLEX P-376^®, which are manufactured by Rohm and Haas, Philadelphia, PA, U.S.A., and JONCRYL 74^® and JONCRYL 624^®, which are manufactured by S.C. Johnson, Racine, WI, U.S.A. In another embodiment, the latex is JONCRYL 74^® or RHOPLEX P-376^®.

The latex used in the present invention can be a homopolymer or copolymer prepared from the polymerization of one or more monomeric residues. The monomeric residues disclosed in U.S. Patent No. 4,258,104 to Lee et al, which are herein incoφorated by this reference, are useful for preparing the latexes of the present invention. In one embodiment, the latex is JONCRYL 74^®, which is a polymer prepared from the monomeric residues 2-ethylhexyl acrylate and styrene, which can also include butyl acrylate or methylmethacrylate. The amount of each monomer used for preparing the latex can very depending upon the desired property of the latex. In one embodiment, by decreasing the amount of styrene in the latex, the latex will become softer. In another embodiment, by increasing the amount of styrene in the latex, the latex will become harder. Procedures for polymerizing these monomers to produce latexes of the present invention are known in the art.

In one embodiment, the latex used in the present invention can be in the form of solid, such as a powder. In another embodiment, the latex can be added to water to produce a dispersion prior to the addition of the colloidal silica and alcohol. In one embodiment, the amount of latex in the aqueous composition of the present invention is from 1 to 50 %, preferably from 2 to 30 % by weight, and more preferably from 2 to 12 % by weight of the aqueous composition. In another embodiment of the present invention, the latex is a dispersion comprising 48.5% by weight latex in water.

The aqueous composition of the present invention also comprises an alcohol. The alcohol of the present invention comprises a monohydric alcohol, a glycol, a polyhydric alcohol, or a combination thereof. The term "monohydric alcohol" is defined as any compound having one hydroxyl group. The term "glycol" is defined as any compound having two hydroxyl groups. The term "polyhydric alcohol" is defined as any compound having three or more hydroxyl groups. In one embodiment, the alcohol is soluble in water. In another embodiment, the alcohol is less volatile than water. In another embodiment, the alcohol component is a glycol that is partially or fully esterified.

In one embodiment, the alcohol is a monohydric alcohol comprising methanol, ethanol, 1-propanol, ethylene glycol monobutyl ether, or a combination thereof.

In one embodiment, the alcohol is a glycol or polyhydric alcohol having the structure H[OCH₂CH₂]_mOH, wherein m is an integer of from 2 to 14; a compound having the structure H[OCH(CH₃)(H)CH]_nOH, wherein n is an integer of from 1 to 10; a compound having the structure HOCH₂(CHOH)_pCH₂OH, wherein p is an integer of from 1 to 4; or a combination thereof. In another embodiment, the alcohol comprises a mixture of a compound having the structure H[OCH₂CH₂]_mOH, wherein m is an integer of from 2 to 10, and a compound having the structure H[OCH(CH₃)(H)CH]_nOH, wherein n is an integer of from 1 to 10.

In one embodiment, the alcohol comprises a compound having the structure H[OCH₂CH₂]_mOH, wherein m is an integer of from 2 to 10. Examples of alcohols having the structure H[OCH₂CH₂]_mOH include, but are not limited to, diethylene glycol, triefhylene glycol, or polyethylene glycol. In one embodiment, the polyethylene glycol has a molecular weight of from 200 to 600, preferably from 300 to 600, and preferably from 400 to 600.

In another embodiment, the alcohol comprises a compound having the structure HOCH₂(CHOH)_pCH₂OH, wherein p is an integer of from 1 to 4. Examples of alcohols having the structure HOCH₂(CHOH)_pCH₂OH include, but are not limited to, glycerine or sorbitol.

In another embodiment, the alcohol can be a higher saccharide. Examples of higher saccharides include, but are not limited to, glucose or sucrose.

In another embodiment, the alcohol comprises a compound having the structure H[OCH(CH₃)(H)CH]_nOH, wherein n is an integer of from 1 to 10. Examples of alcohols having the structure H[OCH(CH₃)(H)CH]_nOH include, but are not limited to, propylene glycol, dipropylene glycol, or tripropylene glycol. The alcohol having the structure H[OCH(CH₃)(H)CH]_nOH is prepared by the ring-opening polymerization of propylene oxide. When the epoxide opens, a mixture of isomers is produced. In one embodiment of the present invention, a mixture of isomers having the structure H[OCH(CH₃)(H)CH]_nOH is used. The designation "(CH₃)(H)" refers to the methyl and hydrogen moieties forming isomers by being attached to either of the "OCH" or "CH" moieties. The amount of alcohol present in the aqueous composition can vary depending upon the selection of the alcohol selected. In one embodiment, the alcohol is from 3 to 90 %, preferably from 7 to 17 % by weight of the aqueous composition.

In another embodiment, a tri-alcohol such as triethanolamine can be added to the aqueous composition.

The aqueous composition of the present invention can include additional additives known in the art that are typically used in the paper process and products. Examples of other additives that can be added include, but are not limited to, dyes, filler pigments, retention aids, thickeners, defoamers, and wet and dry strength additives. The amount of the additive that is added to the aqueous composition is known in the art.

In one embodiment, the pH of the aqueous composition is from 7.5 to 10, preferably from 7.8 to 9.9. The pH of the aqueous composition varies depending upon the selection of the colloidal silica.

The colloidal silica, latex, and alcohol can be added in any order to water to produce the aqueous composition of the present invention. In one embodiment, the aqueous composition is from 5 to 90 %, preferably from 40 to 80 % by weight water. In another embodiment, the aqueous composition is a suspension or sol. The weight percents for the silica, latex, alcohol, and water are based on the total weight of the aqueous composition. The aqueous compositions of the present invention can be further diluted with water. The amount of dilution can vary depending upon the technique used to contact the paper product with the aqueous composition. In one embodiment, one part of the aqueous composition is diluted with from 1 to 20 parts water, preferably from 1 to 10 parts water.

In one embodiment, colloidal silica, diethylene glycol, and JONCRYL 74^® are added to water to produce the aqueous composition of the present invention. In another embodiment, colloidal silica, diethylene glycol, and RHOPLEX P-376^® are added to water to produce the aqueous composition of the present invention.

The aqueous composition of the present invention is typically applied to the surface of the paper product. Methods for contacting the surface of the paper product with the aqueous composition are known in the art. Typically, the surface of the paper product is roll coated, sprayed, or applied via size press with the aqueous composition. In one embodiment, the aqueous composition is sprayed onto the surface of the paper product.

In one embodiment, when the paper product is roll coated with the aqueous composition, the latex, colloidal silica, and alcohol forms a film on the surface of the paper upon removal of water. In another embodiment, when the aqueous composition is sprayed onto the surface of the paper product, the latex, colloidal silica and alcohol forms a viscous material on the surface of the paper product upon removal of the water.

Any paper product is suitable for use in the present invention. Examples of paper products include, but are not limited to, newspaper, linerboard, xerographic office paper, magazine paper, or office paper.

One object of the present invention is to enhance the anti-skid or friction properties of paper. The property of paper that predicts the tendency of the paper to slide or slip when in contact with another paper product or other medium is friction. The friction of a paper substrate is defined by a quantitative value, the coefficient of friction. The static coefficient of friction measures the force or energy required to start an object in motion and the kinetic coefficient of friction relates to the force required to keep the body in motion once it has started moving.

One method for quantifying the static and kinetic coefficients of friction is by the horizontal plane method. In this method, a sheet of paper (top sheet) is placed on top of a second sheet of paper (bottom sheet). A sled or weight of known mass is affixed to the top sheet and the bottom sheet, wherein the bottom sheet is affixed to the horizontal plane. The sled is then pulled at a constant speed. The force required to begin movement of the sled (static) is recorded and the force required to maintain the sled in motion (kinetic or dynamic) is also recorded. A force gauge or load cell is applicable to measure this value. The TAPPI Test Method T549 pm-90 is the test method used for uncoated writing and printing paper and the TAPPI Test Method T816 om-92 is used for corrugated and solid fiberboard.

In general, the static coefficient of friction is 10 to 20% higher than the kinetic coefficient of friction. In one embodiment, the paper product has a kinetic coefficient of friction of from 0.35 to 0.66 after the paper product has been contacted with the aqueous composition of this invention.

Another method for quantifying the anti-skid or friction properties of paper is to measure the slide angle. This method determines the coefficient of static friction of a material by measuring the angle at which one test surface begins to slide against another inclined surface as the incline is increased at a constant and prescribed rate. The TAPPI Test Method T548 pm-90 is the test method used for uncoated writing and printing paper and the TAPPI Test Method T815 om-95 is used for packaging materials.

The applicants have unexpectedly discovered that when a paper product is contacted with an aqueous composition of the present invention, the printability properties of the paper product are also enhanced. One way to quantify the printability of a paper product is by determining the printability index of the paper product. A sample of paper was printed via a semi-automated bench scale print device, and the resulting color density was measured in six different areas with an ink densitometer. The average value of those six measurements is referred to as the printability index.

Not wishing to be bound by theory, the water-insoluble latex of the present invention prevents the ink from spreading out along the surface of the paper product once the ink has been applied to the paper product. Moreover, the colloidal silica also prevents the ink from spreading along the surface of the paper product, which also results in increased printability. The prior art does not teach the use of a latex of the present invention in combination with colloidal silica and an alcohol in order to enhance the friction properties and both the friction and printability properties of paper.

In addition, the sizing properties of a paper product are maintained or increased when a paper product was contacted with the aqueous composition of the present invention. Sizing properties were determined by the Hercules Sizing Tester (HST), which measures the penetration time required for an aqueous dye to pass through the paper sheet that is being tested.

Finally, the presence of the alcohol in the aqueous composition also provides a number of advantages. First, the aqueous compositions of the present invention are stable compared to prior art compositions when the alcohol is not present. Second, the aqueous composition of the present invention is stable to freeze-thaw cycles. Lastly, aqueous compositions composed of silica that do not possess an alcohol of the present invention tend to form deposits at the tips of sprayers, which ultimately plugs the tips of the sprayer. This results in an additional, time-consuming step of scrubbing the tips in order to remove the deposits. When the composition of the present invention is used, no tip plugging was observed.

EXAMPLES

The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the methods and compositions claimed herein are made and evaluated, and are intended to be purely exemplary of the invention and are not intended to limit the scope of what the inventors regard as their invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at room temperature and pressure is at or near atmospheric.

Example 1

The aqueous composition of the present invention was evaluated to determine its ability to impart anti-skid or friction properties to paper. JONCRYL 74^® was used as a 48.5 % dispersion in water. The silica was used as a sol (41% by weight silica in water). The amount of silica used in the formulations is expressed as % by weight dry silica. Formulation (1) is composed of 38 % by weight silica, 14 % by weight glycerine, and 48 % by weight water. Formulation (2) is composed of 37.6 % by weight silica, 8 % by weight diethylene glycol, 0.07 % by weight biocide, and 54.3 % by weight water. Formulation (3) is composed of 30.75 % by weight silica, 14.58 % by weight diethylene glycol, 10 % by weigh JONCRYL 74^®, 0.07 % by weight biocide, and 44.6 % by weight water.

The formulations were diluted with water in order to facilitate the application of the formulations unto the rollers. The formulations were sprayed on the paper roll prior to the reel turnup drum on the papermaking machine. The slide angle of the linerboard was determined by the TAPPI Test Method T815 om-95, and the results are summarized in Table 1.

Table 1 shows that formulation (3), which is an aqueous composition of the present invention, provides the greatest slide angle to the paperboard at the winder. Also, when 42 pound linerboard was tested, the slide angle loss through the winder was only 0.4 degrees when using the present invention versus a degree loss of 3.3 and 1.4 through the winder using formulations (1) and (2), respectively.

Example 2

The impact on print quality was evaluated on the paper products produced in

Example 1 using formulations (l)-(3). Test samples were printed via a semi-automated bench scale print device and the resulting color densities were measured with an ink densitometer. Six measurements were taken in the cross direction on each sample and an average ink density value was computed and is referred to as the printability index in Table 2.

The data in Table 2 indicates a 14 % increase in printability when the linerboard is contacted with formulation (3) compared to linerboard contacted with formulation (1). This data shows that an aqueous composition of the present invention increases the printability of linerboard.

Example 3

In order to compare the propensity to form deposits and the cleanability of the formulations of the present invention with prior art formulations, experiments were carried out in a four tip spray bar with the same tips used in actual mill applications. The spray was directed against an originally transparent plastic screen. The suπounding surfaces were metallic. The four tips were commercial tips made of plastic or of stainless steel.

Three formulations were tested. Formulation A is composed of 41 % by weight dry silica and 59 % by weight water. Formulation B is composed of 30.75 % by weight dry silica, 25 % by weight JONCRYL 74^®, and 44.25 % by weight water. Formulation C is composed of 30.75 % by weight dry silica, 14.58 % by weight diethylene glycol, 10 % by weight JONCRYL 74^®, 0.07 % by weight biocide, and 44.6 % by weight water.

Formulation A lead to the formation of white deposits within one hour of spraying. Scrubbing was required to remove the deposits. Formulation B produced deposits that even harder to remove from the spray tip when compared to formulation A. By contrast, formulation C, which is an aqueous composition of the present invention, resulted in the formation of a clear, sticky material at the tip. In this case, the tip was readily rinsed off with water. Furthermore, no tip plugging was observed after stopping, air drying the area, and restarting the spraying when the aqueous composition of the present invention was used.

This experiment shows that the aqueous compositions of the present invention avoid the application problems that are typically encountered when using prior art paper coating compositions.

Example 4

Tests were performed in order to determine the appearance and consistency of a resultant deposit formed by the removal of water from various aqueous compositions. A number of aqueous compositions were prepared and placed in aluminum dishes (Table 3). Water makes up the remainder of the composition such that the sum of the components is equal to 100 parts. After three days at room temperature, evaporation of the water produced a deposit. The appearance of the resulting solid was observed and the results are summarized in Table 3.

The formation of a solid deposit suggests it will be difficult to dissolve the solid in water as compared to a paste or film.

The results in Table 3 suggests that the deposit produced by Runs 1-3, which are aqueous composition of the present invention, will dissolve in water. Run 4, which is prior art composition, will be harder to dissolve in water since it is a solid. Run 5 is a control. The translucent paste of Run 2 is even more prefeπed to the white skin or film of Runs 1 and 3, due to potential better water redispersability.

Example 5

Formulation (3) of Example 1 was applied to a 20 pound per 3000 square feet basis weight sheet of xerographic paper in the presence and absence of starch. Starch is a common additive used in size press applications. The starch was also added in the size press run tank. The amounts of formulation (3) used are expressed in pounds per ton (ppt). The static and kinetic coefficient of friction and the sizing properties of the paper were measured, and the results are shown in Table 4.

The data in Table 4 reveals that the static coefficient of friction (SCOF) and kinetic coefficient of friction (KCOF) increases over the base sheet when formulation (3) is used in the presence or absence of starch. Moreover, the sizing properties (HST) are maintained or increased when the paper product is treated with formulation (3) in the absence of starch.

Throughout this application, various publications are referenced. The disclosures of these publications in their entireties are hereby incoφorated by reference into this application in order to more fully describe the state of the art to which this invention pertains. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

What is claimed is:

1. A method for enhancing the anti-skid properties of a paper product, comprising contacting the paper product with an aqueous composition, comprising:

(a) a colloidal silica;

(b) a latex; and

(c) an alcohol.

2. The method of Claim 1, wherein the colloidal silica comprises aluminate modified silica.

3. The method of Claim 1, wherein the colloidal silica has a particle size of from 5 to 160 nm.

4. The method of Claim 1 , wherein the colloidal silica has a particle size of from 60 to 90 nm.

5. The method of Claim 1 , wherein the colloidal silica has a particle size of from 7 to 30 nm.

6. The method of Claim 1, wherein the colloidal silica is a mixture of colloidal silica of from 7 to 30 nm and from 60 to 90 nm.

7. The method of Claim 1, wherein the colloidal silica is from 0.5 to 50 % by weight of the composition.

8. The method of Claim 1, wherein the colloidal silica is from 10 to 45 % by weight of the composition.

9. The method of Claim 1, wherein the latex comprises a styrene butadiene rubber, a vinyl acetate homopolymer, a vinyl acrylic copolymer, an acrylic polymer, a styrene-acrylic polymer, or a combination thereof.

10. The method of Claim 1, wherein the latex comprises a styrene-acrylic polymer.

11. The method of Claim 1 , wherein the latex is a polymer prepared from a monomeric residue comprising butyl acrylate, 2-ethylhexyl acrylate, methylmethacrylate, or styrene, or a combination thereof.

12. The method of Claim 1, wherein the latex is from 1 to 50 % by weight of the composition.

13. The method of Claim 1, wherein the latex is from 2 to 30 % by weight of the composition.

14. The method of Claim 1, wherein the alcohol comprises a monohydric alcohol, a glycol, a polyhydric alcohol, or a combination thereof.

15. The method of Claim 1, wherein the alcohol comprises methanol, ethanol, 1- propanol, ethylene glycol monobutyl ether, or a combination thereof.

16. The method of Claim 1, wherein the alcohol comprises a compound having the structure H[OCH₂CH₂]_mOH, wherein m is an integer of from 2 to 14; a compound having the structure H[OCH(CH₃)(H)CH]_nOH, wherein n is an integer of from 1 to 10; a compound having the structure HOCH₂(CHOH)_pCH₂OH, wherein p is an integer of from 1 to 4; or a combination thereof.

17. The method of Claim 1 , wherein the alcohol comprises a compound having the structure H[OCH₂CH₂]_mOH, wherein m is an integer of from 2 to 10.

18. The method of Claim 1, wherein the alcohol comprises diethylene glycol, triethylene glycol, polyethylene glycol, or a combination thereof.

19. The method of Claim 1, wherein the alcohol comprises glycerine, sorbitol, or a mixture thereof.

20. The method of Claim 1, wherein the alcohol comprises a compound having the structure H[OCH(CH₃)(H)CH]_nOH, wherein n is an integer of from 1 to 10.

21. The method of Claim 1 , wherein the alcohol comprises propylene glycol, dipropylene glycol, tripropylene glycol, or a combination thereof.

22. The method of Claim 1, wherein the alcohol comprises a compound having the structure H[OCH₂CH₂]_mOH, wherein m is an integer of from 2 to 10, and a compound having the structure H[OCH(CH₃)(H)CH]_nOH, wherein n is an integer of from 1 to 10.

23. The method of Claim 1, wherein the alcohol is from 3 to 90 % by weight of the composition.

24. The method of Claim 1, wherein the alcohol is from 7 to 17 % by weight of the composition.

25. The method of Claim 1, wherein the aqueous composition is from 5 to 90 % by weight water.

26. The method of Claim 1, wherein the aqueous composition is from 40 to 80 % by weight water.

27. The method of Claim 1, wherein the aqueous composition comprises colloidal silica, an acrylic-styrene latex resin, and diethylene glycol.

28. The method of Claim 1 , wherein the aqueous composition has a pH of from 7.5 to 10.

29. The method of Claim 1, wherein the aqueous composition has a pH of from 7.8 to 9.9.

30. The method of Claim 1, wherein the contacting step comprises spraying the aqueous composition on the surface of the paper product.

31. The method of Claim 1 , wherein the paper product comprises newspaper, liner board, xerographic paper, magazine paper, or office paper.

32. The method of Claim 1 , wherein after the contacting step, the paper product has a kinetic coefficient of friction of from 0.35 to 0.66.

33. The product made by the method of Claim 1.

34. A method for enhancing the anti-skid properties of a paper product, comprising contacting the paper product with an aqueous composition, consisting essentially of:

(a) a colloidal silica;

(b) a latex; and

(c) an alcohol.

35. An aqueous composition for enhancing the anti-skid properties of a paper product, consisting essentially of: (a) a colloidal silica;

(b) a latex; and

(c) an alcohol.

36. An aqueous composition for enhancing the anti-skid properties of a paper product, comprising:

(a) a colloidal silica;

(b) a latex; and

(c) an alcohol,

wherein the composition does not include a polysphere.

37. An aqueous composition for enhancing the anti-skid properties of a paper product, consisting essentially of:

(a) a colloidal silica;

(b) a latex; and

38. The product made by the method of Claim 34.

39. An article comprising a paper product coated with colloidal silica, a latex, and an alcohol.

40. The method of Claim 1, wherein the colloidal silica is anionic colloidal silica.