US20120018109A1

US20120018109A1 - White Tinting File Folder

Info

Publication number: US20120018109A1
Application number: US13/188,507
Authority: US
Inventors: Kapil M. Singh; Michael F. Koenig; Larry Hollmaier
Original assignee: International Paper Co
Current assignee: International Paper Co
Priority date: 2010-07-23
Filing date: 2011-07-22
Publication date: 2012-01-26

Abstract

A paper having thereon a coating composition including at least one pigment and at least one starch is provided. The pigment and the starch may be added to the surface of the paper at a size press during the formation of the paper in a ratio of at least 1:1. Papers coated with the coating composition have an enhanced surface ink density in a subsequent printing or tinting process at an ink usage that is equal or substantially equal to that used to tint conventional, uncoated papers. Accordingly, a paper coated with the coating composition requires the utilization of a lesser amount of ink than that required for conventional file folders to achieve the desired end color. In addition, the coating composition permits for an enhancement in print and/or tint quality if a reduction in ink use is not utilized. A method of forming a file folder is also provided.

Description

TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION

The present invention relates generally to paper products, and more particularly, to heavy weight paper products having thereon a size press application of a coating composition containing a pigment and a starch. A method of making such paper products is also provided.

BACKGROUND OF THE INVENTION

Contemporary businesses use a myriad of paper products while conducting everyday commerce. For example, copy paper, note pads, and file folders to organize and store paperwork. The file folders are typically made using paper material that is relatively stiff and durable so that that contents stored within the file folder are adequately protected and/or so that the folder is able to remain upright independent of any holding device. In addition, these folders may be labeled or tabbed for further organization and identification of the contents stored therein.
To further assist in the organization and identification of stored materials, individual file folders may be color coded. Any number of colors may be utilized to identify or designate a particular category of documents or client. Color coding the file folders permits categories of documents to be quickly identified without the need to read and search for specific folder identifying information. However, the ink required to color the file folders is typically expensive and thus drives the cost of manufacturing colored file folders over that of conventional, uncolored file folders.
Accordingly, there exists a need in the art for a file folder that maintains the physical properties of conventional file folders but utilizes less ink to achieve the desired end color.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a file folder that includes (1) a paper web containing cellulosic fibers and (2) a size-press applied coating composition that at least substantially covers a first surface of the paper web. The coating composition includes a starch and a pigment in a weight ratio of at least 1:4. The paper web treated with the coating composition provides for a reduction of ink in a subsequent flexographic printing process in an amount up to about 13% compared to paper webs not treated with the coating composition. Additionally, the coating composition provides for up to a 7% enhancement in print density when it is applied at a size press. A surface size and/or calcium chloride may also be included in the coating composition. In exemplary embodiments, the pigment is ground calcium carbonate and the starch is an ethylated starch. The paper web may have a density from about 5 lb/3000 ft²/ml to about 15 lb/3000 ft²/ml and a caliper after calendaring from 3 to about 30 mils.
It is another object of the present invention to provide a paperboard that includes (1) cellulosic fibers forming a web and (2) a coating composition at least substantially covering the first major surface of the web. The coating composition includes a pigment and a starch in a 1:1 weight ratio. The coating composition provides for up to a 7% enhancement in print density when applied at a size press. In addition, the web treated with the coating provides for a reduction of ink in a subsequent flexographic printing process in an amount up to about 13% compared to cellulosic webs not treated with the coating composition. In at least one exemplary embodiment, the pigment:starch weight ratio ranges from 4:1 to 1:4.
It is yet another object of the present invention to provide a method of forming a file folder that includes (1) providing a papermaking furnish that includes cellulosic fibers, (2) forming a fibrous web from the papermaking furnish, (3) drying the fibrous web, (4) treating at least a first surface of the fibrous web with a coating composition, and (5) cutting the coated web into a desired shape to form a file folder. The coating composition includes a pigment and a starch in a 1:1 weight ratio. Additionally, the coating composition may include a surface size and/or calcium chloride. The coating composition provides for up to a 7% enhancement in print density when applied at a size press. In addition, the web treated with the coating composition provides for a reduction of ink in a subsequent flexographic printing process in an amount up to about 13% compared to cellulosic webs not treated with the coating composition. The coating composition may also include a surface size and/or calcium chloride.
It is an advantage of the present invention that file folders formed from paper coated with the coating composition have an enhanced surface ink density in a subsequent flexographic printing or tinting process at an ink usage that is equal or substantially equal to that used to tint conventional file folders.
It is another advantage of the present invention that papers coated with the inventive coating composition require the use of a lesser amount of ink than that which is required for conventional file folders to achieve the desired end color.
It is yet another advantage of the present invention that the overall manufacturing costs for a tinted file folder formed from a paper coated with the coating composition is reduced as a result of the reduction in the amount of ink used to tint the file folder.
It is a further advantage of the present invention that a paper web treated with the coating composition provides for a reduction of ink in a subsequent flexographic printing process in an amount up to about 13% compared to paper webs not treated with the coating composition.
It is an additional advantage of the present invention that the inventive coating composition provides for up to a 7% enhancement in print density when applied at a size press.
The foregoing and other objects, features, and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description that follows. It is to be expressly understood, however, that the drawings are for illustrative purposes and are not to be construed as defining the limits of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a graphical illustration of the print density on a Flexiproofer of a base sheet sized with a Chromaset® 700 surface size at a size press; and

FIG. 2 is a graphical illustration of ink density vs. ink volume for ink applied to white tinting file folder paper with a Flexigraphic printing press.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described herein. All references cited herein, including published or corresponding U.S. or foreign patent applications, issued U.S. or foreign patents, or any other references, are each incorporated by reference in their entireties, including all data, tables, figures, and text presented in the cited references. The terms “tinting” and “printing” may be used interchangeably herein. In addition, “coating”, and “coating composition” may be interchangeably used herein.
The present invention is directed to papers or paperboards that enhance the surface ink density in a subsequent printing or tinting process at an ink usage that is equal or substantially equal to that used in conventional printing and tinting processes for untreated paper (i.e., paper not treated with the inventive coating composition). Such improved ink density may be achieved by the application of a coating composition containing at least one pigment and at least one starch at the size press during the formation of the paper. The pigment and the starch may be added to the surface of the paper in a weight ratio of at least 1:1. In at least one exemplary embodiment, the coating composition partially penetrates the paper surface as it is pressed into the web of fibers. The coated paper may advantageously be used to form colored or tinted file folders. As used herein, the term “paper” refers to and includes both paper and paperboard unless otherwise noted.
The paper is provided as a web containing cellulosic pulp fibers such as fibers derived from hardwood trees, softwood trees, or a combination of hardwood and softwood trees. The fibers may be prepared for use in a papermaking furnish by any known suitable digestion, refining, and bleaching operations. The paper may optionally contain recycled fibers and/or virgin fibers. It is to be appreciated that recycled fibers differ from virgin fibers in that the recycled fibers have gone through a drying process at least once. In certain embodiments, at least a portion of the fibers may be provided from non-woody herbaceous plants including, but not limited to, kenaf, hemp, jute, flax, sisal, or abaca, although legal restrictions and other considerations may make the utilization of hemp and other fiber sources impractical or even impossible. Additionally, the paper may include conventional additives such as, for example, starch, mineral fillers, sizing agents, retention aids, and strengthening polymers. Among the fillers that may be used are organic and inorganic pigments such as, for example, polymeric particles such as polystyrene latexes and polymethylmethacrylate, and minerals such as calcium carbonate, kaolin, and talc. In some embodiments, the paper may also include hollow microspheres.
Additionally, the softwood and/or hardwood fibers forming the web may be physically and/or chemically modified. Examples of physical modification include, but are not limited to, electromagnetic and mechanical modification. One non-limiting example of electrical modification includes methods involving contacting the fibers with an electromagnetic energy source such as light and/or an electrical current. Suitable methods for mechanical modification of the fibers include methods that involve contacting an inanimate object with the fibers. Examples of such inanimate objects include objects having sharp and/or dull edges. Mechanical methods may also involve, for example, cutting, kneading, pounding, and/or impaling the fibers.
Examples of chemical modification methods include conventional chemical fiber modification methods such as crosslinking and precipitation of complexes thereon. Non-limiting examples of such chemical modification of fibers may include those found in the following patents: U.S. Pat. Nos. 6,592,717; 6,592,712; 6,582,557; 6,579,415; 6,579,414; 6,506,282; 6,471,824; 6,361,651; 6,146,494; H1,704; U.S. Pat. Nos. 5,731,080; 5,698,688; 5,698,074; 5,667,637; 5,662,773; 5,531,728; 5,443,899; 5,360,420; 5,266,250; 5,209,953; 5,160,789; 5,049,235; 4,986,882; 4,496,427; 4,431,481; 4,174,417; 4,166,894; 4,075,136; and 4,022,965, each of which is expressly incorporated by reference in its entirety.
In exemplary embodiments, the source of the cellulosic pulp fibers is from softwood and/or hardwood trees. The cellulosic fibers in the paper may include from about 0% to about 100% or from about 20% to about 80% by weight dry basis softwood fibers and from about 0% to about 100% or from about 20% to about 80% by weight dry basis hardwood fibers.
In addition, the paper includes a coating composition that includes at least one pigment and at least one starch. The pigment may be selected from natural and synthetic calcium carbonate, calcium sulfate hemihydrate, calcium sulfate dehydrate, silica-treated calcium carbonate, clays such as kaolin, hydrous kaolin, calcined clays, bentonite, calcium sulphate (gypsum), barium sulfate, silicas, silicates, titania, titanium dioxide, alumina, hydrated ammonium silicates, aluminum trihydrate, satin white, talc, barium sulphate, zinc oxide, mica, dolomite, and mixtures thereof. In some embodiments, the pigments are ground to a particle size from 0.0001 to about 0.005 mm, or from about 0.0005 mm to about 0.0025 mm. In any event, the pigment has a size that is non-obtrusive and does not protrude a distance from the paper to be problematic in subsequent processing. In addition to assisting in the enhancement of the print quality on the paper, the pigment contained in the coating composition may fill in irregularities in the paper surface to provide a smooth or substantially smooth surface for the paper and the end product produced from the paper.
The starch utilized in the coating composition may be derived from any native or modified starch, and includes starches such as cereal starches, root or tuber starches, fruit starches, and waxy or high amylase variants thereof. In some embodiments, the starch may be derived from plant sources such as legumes, maize, corn, waxy corn, sugar cane, milo, white milo, potatoes, sweet potatoes, tapioca, rice, waxy rice, peas, sago, wheat, oat, barley, rye, and/or cassava, as well as other plants that have a high starch content. As used herein, the term “modified starch” is meant to denote a starch whose structure has been altered by chemical, enzymatic, or heat treatment. For example, the starch may be esterified, etherified, ethylated, crosslinked, oxidized, or acid modified. It is desirable, however, that the starch not be strongly degraded. In exemplary embodiments, the starch has a viscosity higher than 10 cP at 10% solids and 150° F., or a viscosity higher than 30 cP at 10% solids and 150° F.
The pigment and the starch may be mixed in a weight ratio of at least 1:4 (pigment:starch) and used to treat the surface of the cellulosic web. In some embodiments, the weight ratio may be from 1:2 to 2:1 (pigment:starch). A preferred pigment:starch ratio is 1:1. In exemplary embodiments, and as described in detail below, the coating composition is applied to the fibrous web at the size press during the formation of the paper. It has been surprisingly discovered that, when the inventive coating composition is applied to the paper, there is an increase in the optical density with a set (or predetermined) amount of ink. With the inventive coating composition, a reduction in the amount of tinting material (e.g., ink) that is loaded onto the surface of the paper to obtain a set optical density for the tinted paper is achieved. Additionally, the coating composition surprisingly enhances the ink density in a subsequent tinting process at equal or substantial ink usage. Thus, for example, a file folder formed from such a coated paper requires the utilization of a lesser amount of ink than that which is required for conventional file folders to achieve the desired end color. In essence, the inventive coating composition forces the applied ink to remain on the surface of the paper during (and after) the printing process. As a result, the same level of color (e.g., optical density) can be achieved with less ink. A reduction in the amount of ink utilized to color the file folder correlates to a reduction in overall manufacturing costs. Additionally, the coating composition permits for an enhancement in print and/or tint quality of the formed file folders if a reduction in ink use is not utilized.
The starch may be present in the coating composition in at least one exemplary embodiment in an amount from about 20% to about 80% by weight of the total solids in the coating composition. The pigment may be present in the coating composition in an amount from about 80% to about 20% by weight of the total solids in the coating composition. As used herein, % by weight indicates % by weight of the total solids in the coating composition. In such an embodiment, a formulation that contains 80% starch by weight and 20% pigment by weight implies a weight ratio of starch to pigment of 4:1. However, it is to be appreciated that this pigment:starch ratio may vary from 4:1 to 1:4. The solids content of the formulation (i.e., starch, pigment, and water) may vary from 5% to 30%, with more a typical range from 10% to 20%.
In at least one exemplary embodiment, the coating composition also contains a surface size component such as a styrene acrylic emulsion. Non-limiting examples of suitable surface size components for use in the coating composition include Chromaset® 700, a styrene acrylic emulsion manufactured by Hercules, Inc. and Polygraphix BMP Ultra, a styrene acrylic emulsion manufactured by Kemira. The application of these surface sizes ranges from a pickup rate of 0.25 lb/ton of paper to 5 lb/ton of paper, with typical level at 1 lb/ton to 2 lb/ton of paper.
A variety of papers and paperboards may be provided by a cellulosic web having a wide variety of basis weights and formed from a wide variety of cellulosic fibers. Examples of suitable papers include, but are not limited to, file folders, office papers, form papers, envelope papers, label stock, bristols, and printing and publication papers as well as bleached boards and linerboards. In exemplary embodiments, the cellulosic web is a paperboard web used for making file folders, Bristol-based paper, and other substantially inflexible products for use in an office environment.
Papers formed according to the present invention preferably have a final caliper, after calendaring the paper and any nipping or pressing such as may be associated with subsequent coating, from about 3 to about 30 mils, more preferably from about 7 mils to about 20 mils. In addition, the paper may have basis weights from about 45 lb/3000 ft²to about 300 lb/3000 ft², preferably from about 80 lb/3000 ft²to about 150 lb/3000 ft². The final density of the paper (i.e., basis weight divided by the caliper), may range from about 5 lb/3000 ft²/mil to about 15 lb/3000 ft²/mil, and more preferably from about 7.5 lb/3000 ft²/mil to about 12.5 lb/3000 ft²/mil.
The method of forming the paper of the present invention includes first providing an initial paper furnish. The cellulosic fibers may be in the form of chemically pulped fibers, such as a bleached kraft pulp or sulfite pulps, mechanically treated pulps such as ground wood pulps, and/or other pulp varieties and mixtures thereof, such as chemical-mechanical and thermo-mechanical pulps. In one or more exemplary embodiment, the pulp may be bleached to remove lignins and to achieve a desired pulp brightness according to one or more bleaching treatments known in the art, such as, for example, elemental chlorine-based bleaching sequences, chlorine dioxide-based bleaching sequences, chlorine-free bleaching sequences, elemental chlorine-free bleaching sequences, and combinations or variations of stages of any of the foregoing and other bleaching related sequences and stages.
After bleaching is completed and the pulp is washed and screened, the pulp may be subjected to one or more refining steps. Thereafter, the refined pulp is passed to a blend chest where it is mixed with various additives and fillers typically incorporated into a papermaking furnish, as well as other pulps such as unbleached pulps and/or recycled or post-consumer pulps. The additives may include “internal sizing” agents that are used primarily to increase the contact angle of polar liquids contacting the surface of the paper. Non-limiting examples of these “internal sizing” agents include alkenyl succinic anhydride (ASA), alkyl ketene dimer (AKD), and rosin sizes. In addition, retention aids, including cationic and/or anionic retention aids, may be added at this stage.
Once prepared, the furnish is formed into a single or multi-ply web on a papermaking machine, such as a Fourdrinier machine or any other suitable papermaking machine. The basic methodologies involved in making paper on various papermaking machine configurations are well-known to those of ordinary skill in the art and accordingly, such methods will not be described in detail herein. In general, a furnish consisting of a relatively low consistency aqueous slurry of the pulp fibers (typically about 0.1 to about 1.0%) along with various additives and fillers dispersed therein is ejected from a headbox onto a porous, endless moving forming sheet or wire where the liquid is gradually drained through small openings in the wire until a mat of pulp fibers and the other materials in the furnish is formed on the wire. The still-wet mat or web is then transferred from the wire to a wet press where more fiber-to-fiber consolidation occurs and the moisture is further reduced. The web is then passed to an initial dryer section to remove most of the retained moisture and further consolidate the fibers in the web.
After the web has been initially dried, it may be treated with the inventive coating composition at a size press. It is to be appreciated that the coating composition is an aqueous solution or a slurry containing an appropriate ratio of pigment and starch and that the coating composition has a viscosity suitable for application onto the web by a size press. The size press utilized to apply the coating composition is not particularly limited, and includes size presses such as, but not limited to, a rod size press and a puddle size press. The coating composition may be applied to the paper with a solids content from about 5% to about 25%, desirably from about 8% to about 18%. The pickup rate of solid material in size press may vary from 20 lb/ton to 200 lb/ton, preferably from 50 lb/ton to 150 lb/ton. The size press, in some instances, may press the coating composition into the fibrous web, thereby intermixing the coating composition with the fibers forming a surface of the web and incorporating the coating composition into the surface of the fibrous web. In at least one exemplary embodiment, the applied coating composition remains within the top 0.5 mm of the paper, preferably within 1 mm of the surface of the paper. In addition, greater than 50% of the coating composition is located on the surface of the web.
After treatment in the size press and subsequent drying, the paper is preferably calendered to achieve the desired final caliper, as discussed above, to improve the smoothness and other properties of the web. The calendering may be accomplished by steel-steel calendaring at nip pressures sufficient to provide a desired caliper. It will be appreciated that the ultimate caliper of the paper will be largely determined by the selection of the nip pressure.
Paper materials formed according to the invention may be utilized in a variety of office or clerical applications. In particular, the inventive papers are advantageously used to form file folders or jackets for storing and organizing materials in an office workplace. The manufacture of such folders from paper webs is well-known to those in the paper converting arts and generally includes cutting appropriately sized and shaped blanks from the paper web, typically by “reverse” die cutting, and then folding the blanks into the appropriate folder shape, followed by stacking and packaging steps. The blanks may also be scored beforehand if desired to facilitate folding. The scoring, cuffing, folding, stacking, and packaging operations are ordinarily carried out using automated machinery (well-known to those of ordinary skill in the papermaking industry) on a substantially continuous basis from rolls of the web material fed to the machinery from an unwind stand.
In at least one exemplary embodiment, the coated paper is formed into a file folder. The file folder may be tinted, such as by a flexographic printing process, to achieve a desired end color. As discussed in detail above, it has been surprisingly discovered that with papers treated with the disclosed coating composition, less ink is required to achieve the desired color when compared to papers lacking such a coating composition. Utilizing less ink results in a general overall savings in the manufacturing costs of the file folder. In addition, the coating composition acts to hold the ink on the surface of the paper, thus enhancing the ink density at equal or substantially equal ink usage and enhancing the overall print or tint quality of the file folder.
Having generally described this invention, a further understanding can be obtained by reference to certain specific examples illustrated below which are provided for purposes of illustration only and are not intended to be all inclusive or limiting unless otherwise specified.

EXAMPLES

Example 1

A coating composition containing ground calcium carbonate and ethylated starch was applied to the top of a base sheet of paper on a pilot scale puddle press in a 1:1 weight ratio (calcium carbonate:starch). A control sample consisting of the same paper but treated with only with starch at a size press was provided. 4″×7″ samples of the two papers were printed on a lab bench using a Flexiproofer, which simulates the flexographic printing process on a lab scale. Water-based cyan ink, a commonly used ink in flexographic printing processes for envelopes, was used to print the paper. The printed samples were tested for print density using an X-Rite Densitometer. The results are shown in Table 1.

TABLE 1

				Potential
		Enhancement In	Estimated Cost	Overall
	Print	Print Density vs.	Savings On Ink	Savings
Technology	Density	Control	($/ton)	($/ton)

Control:	0.275	0%	0	0
Starch Only,
size press
applied
1:1 ground	0.295	7%	11	16
calcium
carbonate
(GCC) and
starch, size
press applied

As shown in Table 1, the use of the inventive coating composition provided a significant cost savings ($11.00/ton) in terms of the amount of ink required to tint the paper using a flexographic process. Additionally, the inventive coating composition provided a considerable enhancement in print density, namely, up to a 7% improvement over the control sample.

Example 2

Other Methods for Obtaining Improvements in Optical Density
The experimental conditions are set forth in Table 2.

TABLE 2

Experimental Conditions

	Formulation Pick-Up (lb/ton)	80
	Formulation Solids Content (%)	18
	Linear Speed (ft/min)	100
	Base Paper	Riverdale Copy Paper with
		no surface treatment (20 lb/
		1300 ft²)

This experiment was conducted on a pilot scale utilizing a puddle size press, followed by steam heated drying, using the parameters set forth in Table 2. The additives in the size press starch holding tank were adjusted for each of the Samples shown in Table 3. After each adjustment, the mixture was permitted to mix for 2 minutes prior to ramping up the size press to 100 fpm for one minute to make paper for that particular sample. The paper coming off the size press was wrapped on one core, and each sample was identified on the side by marking the Sample with a marker pen. The paper was slabbed off the roll and separated into the various samples. The samples were then tested for flexographic print quality on a Flexiproofer, which simulates flexographic printing on a lab scale. The print density was measured with an X-Rite Densitometer. The results are set forth in Table 3.

TABLE 3

	Optical	% Improvement In
Sample	Density	Optical Density

Starch^(a)Only	0.91	—
Starch^(b)+ CaCl₂(20 lb/	0.94	3.0
ton)
Starch^(c)+ CaCl₂(20 lb/	0.96	5.2
ton)
and Chromaset ® 700
Surface Size Treatment^(d)
(2.5 lb/ton)

^(a)ethylated starch
^(b)ethylated starch
^(c)ethylated starch
^(d)Chromaset ® 700 is a styrene acrylic emulsion manufactured by Hercules, Inc.

This Example demonstrates alternate ways of improving flexographic print density. It can be seen that the addition of calcium chloride and/or a surface sizes helps in the improvement of the flexographic print density. In addition, it can be concluded that compositions of starch+calcium chloride and starch+a surface size+calcium chloride alone did not meet the improvement in print density obtained by the inventive coating composition.

Example 3

Improvement in Print Density with Addition of Surface Size
This experiment was conducted on a pilot scale using puddle size press, followed by steam heated drying, utilizing the parameters set forth above in Table 2. The level of Chromaset® 700 was progressively increased in the size press starch holding tank. After each addition of Chromaset 700, the mixture was allowed to mix for 2 minutes prior to ramping up the size press to 100 fpm for one minute to make paper for that sample. The paper coming off the size press was wrapped on one core, and each sample was identified on the side with a marker pen. The paper was slabbed off the roll and separated into the various samples. The samples were then tested for flexographic print quality on a Flexiproofer. The print density was measured with an X-Rite Densitometer. The results are set forth in Table 4 and depicted graphically in FIG. 1.

TABLE 4

	Chromaset ® 700
	Surface Size Pick-	Print Density On
Sample	up (lb/ton)	Flexiproofer

1	0	0.987
2	0.25	0.990
3	0.5	0.995
4	0.75	0.990
5	1.0	0.990
6	1.25	0.995
7	1.5	1.000
8	1.75	1.005
9	2.0	1.010

It was concluded that the addition of a surface size to impart a hygroscopic surface on the web kept the water-based flexographic ink on the surface, which enhanced the flexographic print density up to about 2%.

Example 4

Improvement in Print Density
This experiment was conducted on a Flexographic printing press at Western Michigan University, using a 10″ wide, 40″ diameter roll of Georgetown White Tinting File Folder standard product. The ink was applied to the outside of the roll. The speed of printing press was 100 feet per minute. The Cyan Ink used was a water-based flexographic ink with a viscosity of 18 seconds with a #3 Zahn cup. A 2″×2″ square of cyan was repeatedly printed on each 11″ length of paper for one minute.
Three separate points were identified and the ink density was measured. These points are identified in Table 5 and graphically illustrated in FIG. 2.

	TABLE 5

	Ink Volume of
	Anilox^(a)	Cyan Ink
	(BCM)^(b)	Density

	2.77	0.86
	1.98	0.77
	0	0

	^(a)Anilox - a steel roller with tiny dips sculpted into its outer surface. These “cells” contain the ink that is transferred to the rubber “blanket”, which in turn transfers the ink to the paper.
	^(b)BCM—billion cubic microns per square inch

Table 6 depicts values generated from the regression equation of FIG. 2.

	TABLE 6

	Ink Volume of
	Anilox^(a)	Cyan Ink
	(BCM)	Density

	1.8175	0.736
	1.855	0.744
	1.89	0.752
	1.93	0.760
	1.97	0.768
	2.015	0.776
	2.055	0.784
	2.105	0.792
	2.15	0.800
	2.2	0.807
	2.25	0.814

TABLE 7

				Reduction in Ink
Reduction				Cost to
in Ink	Ink	Ink	% Reduction in	Customer,
Density	Density	Volume	Ink Volume/Cost	Dollars per ton

0	0.8	2.15	0	0
1	0.792	2.105	2.09	3.14
2	0.784	2.055	4.42	6.63
3	0.776	2.015	6.28	9.42
4	0.768	1.97	8.37	12.56
5	0.76	1.93	10.23	15.35
6	0.752	1.89	12.09	18.14
7	0.744	1.855	13.72	20.58
8	0.736	1.8175	15.47	23.20

In order to study the effect of ink volume on print density, the only variable in this experiment was the ink volume applied. This Example helped to predict the ink savings associated with an ability to increase the ink density on paper, such as is shown in column 4 of Table 1 in Example 1. In addition, it was concluded that a 7% change in print density afforded by the addition of the coating composition leads to an approximate 13% reduction in ink volume or ink cost per Table 7.
The invention of this application has been described above both generically and with regard to specific embodiments. Although the invention has been set forth in what is believed to be the preferred embodiments, a wide variety of alternatives known to those of skill in the art can be selected within the generic disclosure. The invention is not otherwise limited, except for the recitation of the claims set forth below.

Claims

1. A white tinting file folder comprising:

a paper web including cellulosic fibers, said paper web having a density from about 5 lb/3000 ft²/ml to about 15 lb/3000 ft²/ml and a caliper after calendaring from 3 to about 30 mils; and

a size-press applied coating composition at least substantially covering a first surface of said paper web, said coating composition including:

a starch, and

a pigment,

wherein a weight ratio of said pigment to said starch is at least 1:4, and

wherein said paper web treated with said coating composition provides for a reduction of ink in a subsequent flexographic printing process in an amount up to about 13% compared to paper webs not treated with said coating composition.

2. The file folder of claim 1, wherein said coating composition provides for up to a 7% enhancement in print density when applied at a size press.

3. The file folder of claim 1, wherein said coating composition further includes a surface size, calcium chloride or combination thereof.

4. The file folder of claim 1, wherein at least a portion of said coating composition penetrates the surface of said paper web.

5. The file folder of claim 4, wherein said coating composition remains within 0.5 mm from said first surface of said paper web.

6. The file folder of claim 1, wherein said pigment is selected from calcium carbonate, ground calcium carbonate, kaolin, hydrous kaolin, calcined clays, bentonite, calcium sulphate, barium sulfate, silicas, silicates, titania, titanium dioxide, alumina, hydrated ammonium silicates, aluminum trihydrate, satin white, talc, barium sulphate, zinc oxide, mica, dolomite and mixtures thereof.

7. The file folder of claim 6, wherein said starch is selected from cereal starches, root or tuber starches, fruit starches and waxy or high amylase variants thereof.

8. The file folder of claim 1, wherein said pigment is ground calcium carbonate and said starch is an ethylated starch.

9. A paperboard comprising:

cellulosic fibers forming a web, said web having a first major surface and a second major surface; and

a coating composition at least substantially covering said first major surface, said coating composition including:

a starch, and

a pigment,

wherein a weight ratio of said pigment to said starch is at least 1:1,

wherein at least a portion of said coating composition penetrates said first surface of said web, and

wherein said coating composition provides for up to a 7% enhancement in print density when applied at a size press.

10. The paperboard of claim 9, wherein said coating composition further includes a surface size, calcium chloride and combinations thereof.

11. The paperboard of claim 9, wherein said web treated with said coating composition provides for a reduction of ink in a subsequent flexographic printing process in an amount up to about 13% compared to webs not treated with said coating composition.

12. The paperboard of claim 9, wherein said pigment is selected from calcium carbonate, ground calcium carbonate, kaolin, hydrous kaolin, calcined clays, bentonite, calcium sulphate, barium sulfate, silicas, silicates, titania, titanium dioxide, alumina, hydrated ammonium silicates, aluminum trihydrate, satin white, talc, barium sulphate, zinc oxide, mica, dolomite and mixtures thereof.

13. The paperboard of claim 12, wherein said starch is selected from cereal starches, root or tuber starches, fruit starches and waxy or high amylase variants thereof.

14. The paperboard of claim 9, wherein said weight ratio of said pigment to said starch ranges from 4:1 to 1:4.

15. A method of forming a file folder comprising:

providing a papermaking furnish including cellulosic fibers;

forming a fibrous web from said papermaking furnish;

drying said fibrous web;

treating at least a first surface of said fibrous web with a coating composition to form a coated web, said coating composition including:

a starch; and

a pigment,

wherein a weight ratio of said pigment to said starch is at least 1:1, and

wherein said fibrous web treated with said coating composition provides for a reduction of ink in a subsequent flexographic printing process in an amount up to about 13% compared to fibrous webs not treated with said coating composition; and

cutting said coated web into a desired shape for form a file folder.

16. The method of claim 16, wherein greater than 50% of said coating composition is located on said first surface of said fibrous web.

17. The method of claim 15, wherein said coating composition further includes a member selected from a surface size, calcium chloride and mixtures thereof.

18. The method of claim 17, wherein said coating composition provides for up to a 7% enhancement in print density when applied at a size press.

19. The method of claim 17, wherein said pigment is selected from calcium carbonate, ground calcium carbonate, kaolin, hydrous kaolin, calcined clays, bentonite, calcium sulphate, barium sulfate, silicas, silicates, titania, titanium dioxide, alumina, hydrated ammonium silicates, aluminum trihydrate, satin white, talc, barium sulphate, zinc oxide, mica, dolomite and mixtures thereof.

20. The method of claim 19, wherein said starch is selected from cereal starches, root or tuber starches, fruit starches and waxy or high amylase variants thereof.