Patent Application
20080216975
This invention is directed to a roll paper product having highly defined embossments and wherein the roll paper product is such that it has the appearance of tightly packed, or non-corrugated, edges.
Consumers often make conclusions regarding the quality of a product based on the product's appearance. For example, a consumer may make a judgment about a product based on its appearance while the product is on the shelf. However, many consumers do not stop opining about a product once they take the product home. Many consumers may make a second judgment about the product based on the product's appearance again once the product is being used in that consumer's home. That being said, providing a positive visual experience to the consumer may provide a variety of obstacles for a manufacturer. For instance, increasing the visibility of one positive visual aspect of a product may cause another positive visual aspect of that product to decrease.
Some products have certain qualities associated with certain visual signals. For example, a roll paper towel product that has deep, crisp, and clear embossments tends to convey a product that is highly absorbent, strong, and soft. Similarly, a roll paper towel product in which the surfaces formed from the plies of paper being wound around an axis, or machine direction edges, of the roll do not have many gaps or spaces is perceived by the consumer to provide a good value because it is often thought that a roll paper product having less corrugation has more sheets than a roll paper product having more corrugation. However, when a roll paper product has exceptionally deep embossing, this roll paper product tends to cause the edges of the roll to have a higher level of corrugation than roll paper products with less deep embossing and the same number of sheets.
Thus, there exists the need for roll paper products and methods of cutting rolled paper products to optimize the machine direction edges of the cut rolls such that the consumer will not make any negative conclusions about the product.
The present invention relates to a roll paper product comprising a machine direction, cross machine direction, two machine direction edges, and one or more plies of a fibrous structure having a pattern embossed on the surface thereof, wherein the embossing pattern comprises a plurality of embossments having a height, one or more first tracts having a cross machine direction width, and one or more second tracts having a cross machine direction width, wherein the first tract has the lower percent unembossed than the second tract; and wherein the roll paper product has been cut such that at least one machine direction edge is tangential to a first tract.
In another embodiment, the present invention relates to a method for cutting a paper log into rolls of paper product wherein the method comprises: providing a paper log comprising a machine direction, a cross machine direction, and one or more plies of a fibrous structure; dividing the surface of the embossed paper plies into two or more tracts along the machine direction; measuring the percent of unembossed areas within each tract and identifying one or more first tracts having a cross machine direction width and one or more second tracts having a cross machine direction width wherein the one or more first tracts have a lower percent of unembossed areas than the one or more second tracts; and cutting the paper log to form roll paper products comprising a machine direction, a cross machine direction, one or more plies of an embossed paper product, and 2 machine direction edges; wherein the paper log is cut such that at least one machine direction edge is tangential to a first tract.
In another embodiment, the present invention relates to a roll paper product comprising a machine direction, cross machine direction, two machine direction edges, and one or more plies of a cellulosic fibrous structure having a pattern embossed on the surface thereof: wherein the embossing pattern comprises a plurality of embossments having a height of from about 900 μm to about 1800 μm, one or more first tracts having a cross machine direction width, and one or more second tracts having a cross machine direction width, wherein the first tracts has a lower percent unembossed than the second tracts and wherein a first tract and a second tract comprise an Unemboss to Emboss factor of from about 1 to about 2.3; wherein the roll paper product has been cut such that at least one edge is tangential to from about ⅓ to about ⅔ of the cross machine direction width of a first tract; and wherein the roll paper product has a length of from about 3 inches to about 13 inches.
As used herein, “paper product” refers to any formed, fibrous structure products, traditionally, but not necessarily, comprising cellulose fibers. In one embodiment, the paper products of the present invention may include tissue-towel paper products and toilet tissue products.
As used herein, “roll paper product” refers to any paper product that is wound about an axis. In an embodiment, a roll paper product is provided by winding a paper product around a core.
As used herein, “ply” or “plies”, as used herein, means an individual fibrous structure or sheet of fibrous structure, optionally to be disposed in a substantially contiguous, face-to-face relationship with other plies, forming a multi-ply fibrous structure. It is also contemplated that a single fibrous structure can effectively form two “plies” or multiple “plies”, for example, by being folded on itself. In one embodiment, the ply has an end use as a tissue-towel paper product. A ply may comprise one or more wet-laid layers, air-laid layers, and/or combinations thereof. If more than one layer is used, it is not necessary for each layer to be made from the same fibrous structure. Further, the layers may or may not be homogenous within a layer. The actual makeup of a fibrous structure product ply is generally determined by the desired benefits of the final tissue-towel paper product, as would be known to one of skill in the art. The fibrous structure may comprise one or more plies of non-woven materials in addition to the wet-laid and/or air-laid plies.
As used herein, “fibrous structure” means an arrangement of fibers produced in any papermaking machine known in the art to create a ply of paper. “Fiber” means an elongate particulate having an apparent length greatly exceeding its apparent width. More specifically, and as used herein, fiber refers to such fibers suitable for a papermaking process. The present invention contemplates the use of a variety of paper making fibers, such as, natural fibers, synthetic fibers, as well as any other suitable fibers, starches, and combinations thereof. Paper making fibers useful in the present invention include cellulosic fibers commonly known as wood pulp fibers. Applicable wood pulps include chemical pulps, such as Kraft, sulfite and sulfate pulps; mechanical pulps including groundwood, thermomechanical pulp; chemithermomechanical pulp; chemically modified pulps, and the like. Chemical pulps, are particularly well suited in tissue towel embodiments since they are known to those of skill in the art to impart a superior tactical sense of softness to tissue sheets made therefrom. Pulps derived from deciduous trees (hardwood) and/or coniferous trees (softwood) can be utilized herein. Such hardwood and softwood fibers can be blended or deposited in layers to provide a stratified web. Exemplary layering embodiments and processes of layering are disclosed in U.S. Pat. Nos. 3,994,771 and 4,300,981. Additionally, fibers derived from non-wood pulp such as cotton linters, bagesse, and the like, can be used. Additionally, fibers derived from recycled paper, which may contain any or all of the pulp categories listed above, as well as other non-fibrous materials such as fillers and adhesives used to manufacture the original paper product may be used in the present web. In addition, fibers and/or filaments made from polymers, specifically hydroxyl polymers, may be used in the present invention. Non-limiting examples of suitable hydroxyl polymers include polyvinyl alcohol, starch, starch derivatives, chitosan, chitosan derivatives, cellulose derivatives, gums, arabinans, galactans, and combinations thereof. Additionally, other synthetic fibers such as rayon, lyocel, polyester, polyethylene, and polypropylene fibers can be used within the scope of the present invention. Further, such fibers may be latex bonded. Other materials are also intended to be within the scope of the present invention as long as they do not interfere or counter act any advantage presented by the instant invention.
As used herein, “Machine Direction” or “MD” means the direction parallel to the flow of the fibrous structure through the papermaking machine and/or product manufacturing equipment.
As used herein, “Cross Machine Direction” or “CD” means the direction perpendicular to the machine direction in the same plane of the fibrous structure and/or fibrous structure product comprising the fibrous structure.
As used herein, “Machine Direction pitch” or “MD pitch” means the distance between the centers of two emboss protrusions that are adjacent and collinear in the machine direction.
As used herein, “Cross Machine Direction pitch” or “CD pitch” means the distance between the centers of two emboss protrusions that are adjacent and collinear in the cross machine direction.
As used herein, “Machine Direction edge” or “MD edge” means the surface of a roll paper product parallel to the machine direction that is formed as a result of the sheets of roll paper product being wound about an axis.
As used herein “paper log” or “log” refers to a long roll of paper that has not been cut into smaller rolls that are suitable for sale to consumers. Paper logs may be from about 80 inches to about 120 inches in length and from about 3 inches to about 8 inches in diameter. In one embodiment a paper log may be disposed around an inner core that may be made of any suitable material for supporting the paper log.
As used herein, “tract” refers to one or more bands that divides an emboss pattern. In one embodiment, a tract comprises boundaries that are parallel in the machine direction.
The embossing of webs, such as the paper webs that are used to make paper products, is well known in the art. Embossing of webs can provide improvements to the web such as increased bulk, improved water holding capacity, improved aesthetics and other benefits. Both single ply and multiple ply (or multi-ply) webs are known in the art and can be embossed. Multi-ply paper webs are webs that include at least two plies superimposed in face-to-face relationship to form a laminate.
During a typical embossing process, a web is fed through a nip formed between juxtaposed generally axially parallel rolls or cylinders. Embossing protrusions on the rolls co7 mpress and/or deform the web. If a multi-ply product is being formed, two or more plies are fed through the nip and regions of each ply are brought into a contacting relationship with the opposing ply. The embossed regions of the plies may produce an aesthetic pattern and provide a means for joining and maintaining the plies in face-to-face contacting relationship.
Embossing is typically performed by one of two processes; knob-to-knob embossing or nested embossing. Knob-to-knob embossing typically consists of generally axially parallel rolls juxtaposed to form a nip within which the embossing protrusions, or knobs, on opposing rolls are aligned to press the web between the faces of the aligned protrusions. Nested embossing typically consists of embossing protrusions of one roll meshed in between the embossing protrusions of the other roll. Examples of knob-to-knob embossing and nested embossing are illustrated in the prior art by U.S. Pat. Nos. 3,414,459, 3,547,723, 3,556,907, 3,708,366, 3,738,905, 3,867,225, 4,483,728, 5,468,323, 6,086,715, 6,277,466, 6,395,133, and 6,846,172 B2.
Knob-to-knob embossing generally produces a web comprising very compressed areas and surrounding pillowed regions which can enhance the thickness of the product. However, the pillows have a tendency to collapse under pressure due to lack of support. Consequently, the thickness benefit is typically lost during the balance of the converting operation and subsequent packaging, diminishing the quilted appearance and/or thickness benefit sought by the embossing.
Nested embossing has proven in some cases to be a more desirable process for producing products exhibiting a softer, more quilted appearance that can be maintained throughout the balance of the converting process, including packaging. As the two plies travel through the nip of the embossing rolls, the patterns are meshed together. Nested embossing aligns the knob crests on the male embossing roll with the low areas on the female embossing roll. As a result, the embossed sites produced on one side of the structure provide support for the uncontacted side of the structure and the structure between embossment sites.
Another type of embossing, deep-nested embossing has been developed and used to provide unique characteristics to the embossed web. Deep-nested embossing refers to embossing that utilizes paired emboss rolls, wherein the protrusions from the different emboss rolls are coordinated such that the protrusions of one roll fit into the spaces between the protrusions of the other emboss roll. Exemplary deep-nested embossing techniques are described in U.S. Pat. Nos. 5,686,168 and 5,294,475; U.S. patent application Ser. Nos. 11/059,986 and 10/700,131 and U.S. Patent Provisional Application Ser. No. 60/573,727. Exemplary high definition embossing techniques are described in U.S. patent application Ser. No. 11/516,892 and U.S. Ser. No. 10/952,119.
An exemplary process for embossing a web substrate in accordance with the present invention incorporates the use of a deep-nested embossment technology. By way of a non-limiting example, a tissue ply structure is embossed in a gap between two embossing rolls. The embossing rolls may be made from any material known for making such rolls, including, without limitation, steel, rubber, elastomeric materials, and combinations thereof. As known to those of skill in the art, each embossing roll may be provided with a combination of emboss protrusions and gaps. Each emboss protrusion comprises a base, a face, and one or more sidewalls. Each emboss protrusion also has a height, h. The height of the emboss protrusions may range from about 1.8 mm. (0.070 in.) to about 3.8 mm. (0.150 in.), preferably from about 2.0 mm. (0.080 in.) to about 3.3 mm. (0.130 in.).
While the apparatus shown in
In yet another possible embodiment of the present invention to produce multi-ply products, as shown in
It should be noted that with respect to any of the methods described herein, the number of plies is not critical and can be varied, as desired. Thus, it is within the realm of the present invention to utilize methods and equipment that provide a final roll paper product having a single ply, two plies, three plies, four plies or any other number of plies suitable for the desired end use. In each case, it is understood that one of skill in the art would know to add or remove the equipment necessary to provide and/or combine the different number of plies. Further, it should be noted that the plies of a multi-ply roll paper product need not be the same in make-up or other characteristics. Thus, the different plies can be made from different materials, such as from different fibers, different combinations of fibers, natural and synthetic fibers or any other combination of materials making up the base plies. Further, the resulting web 100 may include one or more plies of a cellulosic web and/or one or more plies of a web made from non-cellulose materials including polymeric materials, starch based materials and any other natural or synthetic materials suitable for forming fibrous webs. In addition, one or more of the plies may include a nonwoven web, a woven web, a scrim, a film a foil or any other generally planar sheet-like material. Further, one or more of the plies can be embossed with a pattern that is different that one or more of the other plies or can have no embossments at all.
In the deep-nested emboss process, one example of which is shown in
In certain embodiments, as shown, for example, in
The “rounding” of the transition region 130 typically results in a circular arc rounded transition region 130 from which a radius of curvature of curvature is determined as a traditional radius of curvature of the arc. The present invention, however, also contemplates transition region configurations which approximate an arc rounding by having the edge of the transition region 130 removed by one or more straight line or irregular cut lines. In such cases, the radius of curvature of curvature r is determined by measuring the radius of curvature of a circular arc that includes a portion which approximates the curve of the transition region 130.
In other embodiments, at least a portion of the distal end of one or more of the embossing protrusions other than the transition regions 130 can be generally non-planar, including for example, generally curved or rounded. Thus, the entire surface of the embossing element spanning between the sidewalls 115 or 215 can be non-planar, for example curved or rounded. The non-planar surface can take on any shape, including, but not limited to smooth curves or curves, as described above, that are actually a number of straight line or irregular cuts to provide the non-planar surface. One example of such an embossing element is the embossing element 62 shown in
One example of an embossed paper product is shown in
Because paper logs are normally cut in the machine direction to form roll paper products, the density of embossments and percentage of unembossed areas may be divided into tracts that are segmented in the machine direction. To divide an emboss pattern 400 into one or more tracts, it is first necessary to identify continuous unembossed elements. For the purpose of identifying continuous unembossed elements, a region that comprises embossments having similar spacing between embossments is said to not be a continuous unembossed element, and will have a percent unembossed (defined below) of zero. As used herein, “similar spacing between embossments” means having less than a 30% variation between PMD and/or PCD. In some embodiments, a continuous unembossed element may be identified as any area having no embossments where two or more embossments (having the same spacing in the machine, and cross machine, direction as the embossments around that area) may have been, but are not, located.
For a tract that encompasses both embossed and unembossed areas, the area of the unembossed area is divided by the sum of the embossed and unembossed areas for that tract to provide the percent unembossed. For a tract that has no unembossed areas then the percent unembossed is 0. Repeat this step for each tract. If two adjacent tracts have the same percentage unembossed then these tracts can be merged into one tract. In an embodiment, the tracts with the lowest percent unembossed are the first tracts. In an embodiment, the tracts with the highest percent unembossed are the second tracts. In other words, the second tracts 442 are tracts that have a higher percent unembossed than the first tracts 441. Any tract with an intermediate percent unembossed are neither first nor second tracts. In one embodiment, the first tract has a percent unembossed from about 0% to about 40%. In another embodiment, the first tract has a percent unembossed from about 0% to about 25%. If there is only one tract, then there the log may be cut anywhere along the pattern.
Referring to
In another embodiment U/E is from about 1 to about 2.3. In another embodiment the U/E is from about 1.5 to about 2.
Methods for cutting a paper log are well known in the art. During a typical papermaking process a paper log roll is processed and then cut into smaller rolls for retail sale. An exemplary process for cutting paper logs is shown in U.S. Pat. No. 5,038,647.
When a highly embossed paper web log is cut into smaller rolls for retail sale the top and bottom surfaces of the rolls, or edges, may exhibit spaces or gaps between the plies that result from the embossing process. This spacing effect is referred to herein as “gapping.” Without being limited by theory it is thought that cutting a paper log within tracts that have a low percent embossments (i.e., having a large number of unembossed areas) causes the differences in height between embossments and unembossed areas to become highly visually apparent on the edges of the resultant paper rolls in the form of gapping.
Embossment height is measured using an Optical 3D Measuring System MikroCAD compact for paper measurement instrument (the “GFM MikroCAD optical profiler instrument”) and ODSCAD Version 4.0 software available from GFMesstechnik GmbH, Warthestraβe E21, D14513 Teltow, Berlin, Germany. The GFM MikroCAD optical profiler instrument includes a compact optical measuring sensor based on digital micro-mirror projection, consisting of the following components:
The GFM MikroCAD optical profiler system measures the height of a sample using the digital micro-mirror pattern projection technique. The result of the analysis is a map of surface height (Z) versus X-Y displacement. The system should provide a field of view of 27×22 mm with a resolution of 21 μm. The height resolution is set to between 0.10 μm and 1.00 μm. The height range is 64,000 times the resolution. To measure a fibrous structure sample, the following steps are utilized:
Click on the icon “Draw Cutting Lines.” On the captured image, “draw” six cutting lines (randomly selected) that extend from the center of a positive embossment through the center of a negative embossment to the center of another positive embossment. Click on the icon “Show Sectional Line Diagram.” Make sure active line is set to line 1. Move the cross-hairs to the lowest point on the left side of the computer screen image and click the mouse. Then move the cross-hairs to the lowest point on the right side of the computer screen image on the current line and click the mouse. Click on the “Align” button by marked point's icon. Click the mouse on the lowest point on this line and then click the mouse on the highest point of the line. Click the “Vertical” distance icon. Record the distance measurement. Increase the active line to the next line, and repeat the previous steps until all six lines have been measured. Perform this task for four sheets equally spaced throughout the Finished Product Roll, and four finished product rolls for a total of 16 sheets or 96 recorded height values. Take the average of all recorded numbers and report in mm, or μm, as desired. This number is the embossment height.
One fibrous structure useful in achieving the roll paper product of the present invention is the through-air-dried (TAD), differential density structure described in U.S. Pat. No. 4,528,239. Such a structure may be formed by the following process.
A Fourdrinier, through-air-dried papermaking machine is used in the practice of this invention. A slurry of papermaking fibers is pumped to the headbox at a consistency of about 0.15%. The slurry consists of about 55% Northern Softwood Kraft fibers, about 30% unrefined Eucalyptus fibers and about 15% repulped product broke. The fiber slurry contains a cationic polyamine-epichlorohydrin wet burst strength resin at a concentration of about 10.0 kg per metric ton of dry fiber, and carboxymethyl cellulose at a concentration of about 3.5 kg per metric ton of dry fiber.
Dewatering occurs through the Fourdrinier wire and is assisted by vacuum boxes. The wire is of a configuration having 41.7 machine direction and 42.5 cross machine direction filaments per cm, such as that available from Asten Johnson known as a “786 wire”.
The embryonic wet web is transferred from the Fourdrinier wire to a TAD carrier fabric. The sheet side of the carrier fabric consists of a continuous, patterned network of photopolymer resin, the pattern containing about 90 deflection conduits per inch. The deflection conduits are arranged in an amorphous configuration, and the polymer network covers about 25% of the surface area of the carrier fabric.
The consistency of the web is about 65% after the action of the TAD dryers operating about a 254° C., before transfer onto the Yankee dryer. An aqueous solution of creping adhesive consisting of animal glue and polyvinyl alcohol is applied to the Yankee surface by spray applicators at a rate of about 0.66 kg per metric ton of production. The fiber consistency is increased to an estimated 95.5% before creping the web with a doctor blade. The Yankee dryer is operated at about 157° C., and Yankee hoods are operated at about 120° C.
The dry, creped web is passed between two calendar rolls and rolled on a reel. The resulting paper has a basis weight of about 23 grams per square meter (gsm) and has a MD stretch of about 21% and a CD stretch of about 9%.
The paper described above is then subjected to the deep-nested embossing process of this invention. Two emboss rolls are engraved with complimentary, nesting embossing protrusions shown in
The embossment pattern of the present example invention is that shown in
In another embodiment of the roll paper product, the cutting process of Example 1 is modified such that the paper of Example 1 is cut within a first tract. The resulting paper yields a product with machine direction edges having relatively little gapping as shown in
It is noted that terms like “specifically,” “preferably,” “typically”, “generally”, and “often” are not utilized herein to limit the scope of the claimed invention or to imply that certain features are critical, essential, or even important to the structure or function of the claimed invention. Rather, these terms are merely intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment of the present invention. It is also noted that terms like “substantially” and “about” are utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation.
The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm”.
All documents cited in the Detailed Description of the Invention are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention. To the extent that any meaning or definition of a term in this written document conflicts with any meaning or definition of the term in a document incorporated by reference, the meaning or definition assigned to the term in this written document shall govern.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
