US20080216975A1

US20080216975A1 - Deeply embossed roll paper products having reduced gapping on the machine direction edges

Info

Publication number: US20080216975A1
Application number: US11/713,930
Authority: US
Inventors: James Paul Farwig; Nicholas Jerome Wilke
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 2007-03-05
Filing date: 2007-03-05
Publication date: 2008-09-11
Also published as: MX2009009297A; WO2008107845A3; CA2679861A1; WO2008107845A2

Abstract

A roll paper product having 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 has 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.

Description

FIELD OF THE INVENTION

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.

BACKGROUND OF THE INVENTION

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.

SUMMARY OF THE INVENTION

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.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view of one embodiment of an apparatus that can be used to perform the deep-nested embossing of the present invention.

FIG. 2 is an enlarged side view of the nip formed between the embossing rolls of the apparatus shown in FIG. 1.

FIG. 3 is a schematic side view of one embodiment of an apparatus that can be used to perform the deep-nested embossing of the present invention.

FIG. 4 is a schematic side view of an alternative apparatus that can be used to perform the deep-nested embossing of the present invention.

FIG. 5 is a side view of the gap between two engaged emboss cylinders of the apparatus for deep-nested embossing of the present invention.

FIG. 6 is a side view of an embodiment of the embossed paper product of the present invention.

FIG. 7 is a plan view of an embodiment of one section of an emboss pattern that may be applied to the surface of the embossed paper product of the present invention.

FIG. 8A is a plan view of an embodiment of one section of an emboss pattern that may be applied to the surface of the embossed paper product produced of the present invention.

FIG. 8B is a plan view of an embodiment of one section of an emboss pattern that may be applied to the surface of the embossed paper product produced by the process of the present invention.

FIG. 9A is a plan view of an embodiment of a paper log that may be used by the process of the present invention.

FIG. 9B is a front view of an embodiment of a paper log that may be used by the process of the present invention.

FIG. 10A is a plan view of an embodiment of a paper roll that has been cut from the paper log of FIGS. 9A-B along lines 550-550 and 560-560.

FIG. 10B is a plan view of an embodiment of a paper roll that has been cut from the paper log of FIGS. 9A-B along lines 550-550 and 560-560.

FIG. 11A is a photograph of an embodiment of an edge of a roll of paper product that has been cut by the process of the present invention.

FIG. 11B is a photograph of an embodiment of an edge of a roll of paper product that has been cut by the process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

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.

Embossing

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.).
FIG. 1 shows one embodiment of the apparatus 10 of the present invention. The apparatus 10 includes a pair of rolls, first embossing roll 20 and second embossing roll 30. (It should be noted that the embodiments shown in the figures are just exemplary embodiments and other embodiments are certainly contemplated. For example, the embossing rolls 20 and 30 of the embodiment shown in FIG. 1 could be replaced with any other embossing members such as, for example, plates, cylinders or other equipment suitable for embossing webs. Further, additional equipment and steps that are not specifically described herein may be added to the apparatus and/or process of the present invention.) The embossing rolls 20 and 30 are disposed adjacent each other to provide a nip 40. The rolls 20 and 30 are generally configured so as to be rotatable on an axis, the axes 22 and 32, respectively, of the rolls 20 and 30 are typically generally parallel to one another. The apparatus 10 may be contained within a typical embossing device housing. Each roll has an outer surface 25 and 35 comprising a plurality of first embossing protrusions 50 and second embossing protrusions 60 (shown in more detail in FIG. 2) which are generally arranged in a non-random pattern. The embossing rolls 20 and 30, including the respective surfaces 25 and 35 of the rolls 20 and 30 as well as the embossing protrusions 50 and 60, may be made out of any material suitable for the desired embossing process. Such materials include, without limitation, steel and other metals, ebonite, and hard rubber or a combination thereof. As shown in FIG. 1, the first and second embossing rolls 20 and 30 provide a nip 40 through which a web 100 can pass. In the embodiment shown, a web 100 is made up of a single ply 80 and is shown passing through the nip 40 in the machine direction MD where it is embossed.
FIG. 2 is an enlarged view of the portion of the apparatus 10 (identified by callout 2 in FIG. 1.) The figure shows a more detailed view of the web 100 passing through the nip 40 between the first embossing roll 20 and the second embossing roll 30. As can be seen in FIG. 2, the first embossing roll 20 includes a plurality of first embossing protrusions 50 extending from the outer surface 25 of the first embossing roll 20. The second embossing roll also includes a plurality of second embossing protrusions 60 extending outwardly from the outer surface 35 of the second embossing roll 30. (It should be noted that when the embossing protrusions 50 and/or 60 are described as extending from a surface of an embossing member, the embossing protrusions may be integral with the surface of the embossing member or may be separate protrusions that are joined to the surface of the embossing member.) As the ply of the unconverted web 80 is passed through the nip 40, it is nested and macroscopically deformed by the intermeshing of the first embossing protrusions 50 and the second embossing protrusions 60. The embossing shown is deep-nested embossing, as described herein, because the first embossing protrusions 50 and the second embossing protrusions 60 intermesh with each other, for example like the teeth of gears. Thus, the resulting embossed web 100 is deeply embossed and nested, as will be described in more detail below, and includes plurality of undulations that can add bulk and caliper to the web 100.
While the apparatus shown in FIG. 1 may be used for webs having one ply, the apparatus may be used to make multi-ply products as well. FIG. 3 shows an embodiment to the process of the present invention where a two ply product is produced where both plies are embossed. The first ply 80 and second ply 90 and resulting web 100 are first joined together between marrying roll 70 and the first embossing roll 20. The plies 80 and 90 can be joined together by any known means, but typically an adhesive application system is used to apply adhesive to one or both of the plies 80 and 90 prior to the plies being passed between the nip 75 formed between the marrying roll 70 and the first embossing roll 20. The combined web 100 is then passed through the nip 40 formed between the first embossing roll 20 and the second embossing roll 30 where it is embossed.
In yet another possible embodiment of the present invention to produce multi-ply products, as shown in FIG. 4, the plies 80 and 90 are passed through the nip 40 formed between the first embossing roll 20 and the second embossing roll 30 where the plies are placed into contact with each other and embossed. At this stage, it is also common to join the webs together using conventional joining methods such as an adhesive application system, but, as noted above; other joining methods can be used. The combined web 100 is then passed through the nip 75 between the first embossing roll 20 and the marrying roll 70. This step is often used to ensure that the plies 80 and 90 of the web 100 are securely joined together before the web 100 is directed to further processing steps or winding.
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 FIG. 5, the embossing protrusions 50 and 60 of the embossing members (in this case embossing plates 21 and 31) engage such that the distal end 110 of the first embossing protrusions 50 extend into the space 220 between the second embossing protrusions 60 of the second embossing roll 30 beyond the distal end 210 of the second embossing protrusions 60. Accordingly, the distal ends 210 of the second embossing protrusions 60 should also extend into the space 120 between the first embossing protrusions 50 of the first embossing roll 20 beyond the distal end 110 of the first embossing protrusions 50. The depth of the engagement E may vary depending on the level of embossing desired on the final product and can be any distance greater than zero. Typical deep-nested embodiments have a engagement E greater than about 0.01 mm (0.000394 inches), greater than about 0.05 mm (0.001969 inches), greater than about 1.0 mm (0.03937 inches), greater than about 1.25 mm (0.049213 inches), greater than about 1.5 mm (0.059055), greater than about 2.0 mm (0.07874 inches), greater than about 3.0 mm (0.11811 inches), greater than about 4.0 mm (0.15748 inches), greater than about 5.0 mm (0.19685 inches), between about 0.01 mm (0.000394 inches) and about 5.0 mm (0.19685 inches) or any number within this range. It should be noted that although the description in this paragraph describes certain relationships between the embossing protrusions 50 and 60 disposed on embossing members that are embossing plates 21 and 31, the same engagement characteristics are applicable to embossing protrusions 50 and 60 that are disposed on embossing members that are not plates, but rather take on a different form, such as, for example, the embossing rolls 20 and 30 shown in FIG. 1.
In certain embodiments, as shown, for example, in FIG. 5, at least some of the first embossing protrusions 50 and/or the second embossing protrusions 60, whether they are linear or discrete, may have at least one transition region 130 between the face and the sidewalls of the protrusion that has a radius of curvature of curvature r. When a transition region is employed, the transition region 130 is disposed between the distal end of the embossing element and the sidewall of the embossing element. (As can be seen in FIG. 5, the distal end of the first embossing element is labeled 110, while the sidewall of the first embossing element is labeled 115. Similarly, the distal end of the second embossing element is labeled 210, while one of the sidewalls of the second embossing element is labeled 215.) The radius of curvature of curvature r is typically greater than about 0.075 mm (0.002953 inches). Other embodiments have radii of greater than 0.1 mm (0.003937 inches), greater than 0.25 mm (0.009843 inches), greater than about 0.5 mm (0.019685 inches), between about 0.075 mm (0.002953 inches) and about 0.5 mm (0.019685 inches) or any number within this range. The radius of curvature of curvature r of any particular transition region is typically less than about 1.8 mm (0.070866 inches). Other embodiments may have embossing protrusions with transition regions 130 having radii of less than about 1.5 mm (0.059055 inches), less than about 1.0 mm (0.03937 inches), between about 1.0 mm (0.03937 inches) and about 1.8 mm (0.070866 inches) or any number within the range. (Although FIG. 5 shows an example of two intermeshing embossing plates 21 and 31, the information set forth herein with respect to the embossing protrusions 50 and 60 is applicable to any type of embossing platform or mechanism from which the embossing protrusions can extend, such as rolls, cylinders, plates and the like.)
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 FIG. 5. Although not wishing to be bound by theory, it is believed that rounding the transition regions 130 or any portion of the distal ends of the embossing protrusions can provide the resulting paper with embossments that are more blunt with fewer rough edges. Thus, the resulting paper may be provided with a smoother and/or softer look and feel.
One example of an embossed paper product is shown in FIG. 6. The embossed fibrous structure 100 comprises one or more plies, wherein at least one of the plies comprises a plurality of discrete embossments 310 and a plurality of linear embossments 315 wherein the difference in elevation between the apex of the discrete embossments 310 and linear embossments 315 comprises an embossment height 320. (Generally, the embossments take on a shape that is similar to the embossing protrusions used to form the embossments, thus, for the purposes of this application, the shapes and sizes of the embossing protrusions described herein can also be used to describe suitable embossments. However, it should be noted that the shape of the embossments may not correspond exactly to the shape of any particular embossing element or pattern of embossing protrusions and thus, embossments of shapes and sizes different than those described herein with regard to the embossing protrusions are contemplated.) In some embodiments, the ply or plies which are embossed are embossed in a deep-nested embossing process such that the embossments exhibit an embossment height h of at least about 650 μm, at least about 800 μm, at least about 900 μm, at least about 1300 μm, at least about 1550 μm, and at least about 1800 μm. In one embodiment, the embossment height is from about 650 μm to about 4000 μm. In another embodiment, the embossment height is from about 800 μm to about 3000 μm. In another embodiment, the embossment height is from about 900 μm to about 1800 μm. In another embodiment, the embossment height is from about 1300 μm to about 1550 μm. The embossment height h of the fibrous structure 100 is measured by the Embossment Height Test method set forth below.

Measuring the Percentage of Unembossed Method

FIGS. 7 and 8 show one embodiment of a portion of an exemplary embossing pattern 400 as it would appear on a paper web comprising a plurality of discrete embossments 310. In one embodiment the diameter of the emboss protrusions used to form the discrete embossments 310 have a diameter D of from about 0.05 inches to about 0.20 inches. In another embodiment, the emboss protrusions used to form the embossments 410 have a diameter D of from about 0.06 inches (1.524 mm) to about 0.15 inches (3.81 mm). In another embodiment, the emboss protrusions used to form the emboss pattern 400 have a cross machine direction pitch P_CDof from about 0.1 inches (2.54 mm) to about 0.25 inches (6.35 mm). In another embodiment, the emboss protrusions used to form the emboss pattern 400 have a P_CDof from about 0.15 inches (3.81 mm) to about 0.2 inches (5.08 mm). In one embodiment, the emboss protrusions used to form the emboss pattern 400 have a machine direction pitch P_MDof from about 0.1 inches (2.54 mm) to about 0.3 inches (7.62 mm). In another embodiment, the emboss protrusions used to form the emboss pattern 410 have a P_MDof from about 0.13 (3.302 mm) inches to about 0.18 inches (4.572 mm).
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 P_MDand/or P_CD. 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.
FIG. 8A shows a nonlimiting example of an emboss pattern 400 that, in one embodiment, may be tessellated with like emboss patterns 400 to form a larger emboss pattern. As stated above, the continuous unembossed areas are any areas having no embossments, although two or more embossments (separated by similar spacing as the surrounding embossments) could have been placed in that space. In the exemplary emboss pattern 400, continuous unembossed areas are hexagons and are delineated by broken lines 430 and referred to as “trace lines.” Tract lines 440 are drawn parallel to the machine direction such that the tract lines 440 touch the outermost edges or points in the cross machine direction of the continuous unembossed areas 430. Each set of parallel tract lines forms a tract. Sketch lines 410 are drawn around the emboss pattern 400 and serve as boundaries for calculating percent unemboss. The area that the embossed and unembossed areas occupy (which is bounded by the sketch lines 410, trace lines 430, and tract lines 440) is measured by calculating the total area for each figure that is bounded by a set of lines sketch lines 410, trace lines 430 and tract lines 440 and has no lines sketch lines 410, trace lines 430, and tract lines 440 running through it.
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 FIG. 8B, the first tracts 441 are any tracts of the pattern which have the lowest percentage unembossed and the second tracts 442 are any tracts of the pattern which have the highest percentage unembossed. In the exemplary embodiment shown in FIG. 8B the first tracts 441 have a percent unembossed of 0 and the second tracts 442 have a percent unembossed of about 23.8%. An ideal cut line 443 is a line in a first tract that is furthest from the adjacent second tracts. In one embodiment an ideal cut line 443 bisects a first tract 441 along the cross machine direction width W_CDof the first tract. In certain embodiments a cut may be made between from about ¼ to about ¾ of the W_CDof the first tract. In another embodiment a cut is made between from about ⅓ to about ⅔ of the W_CDof the first tract. In an embodiment the second tracts 442 have the highest percentage unembossed. In one embodiment, the first tracts 441 have a higher percent unembossed than the second tracts 442. The relationship between the percent unembossed of one first tract and one second tract may be described by a “Unembossed to Emboss factor”, U/E, which is simply the exponential of the percent unembossed of the first tract divided by the percent unembossed of the second tract as described below:
$U / E = Exp [\frac{PU 1}{PU 2}]$

Where:

- U/E is the Unemboss to Emboss factor
- PU1 is the percent unembossed of one first tract
- PU2 is the percent unembossed of one second tract

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.

Cutting the Paper Logs

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.
FIGS. 9A and 9B show an exemplary embodiment of a paper log 500 having the exemplary embossing pattern 400. In one embodiment the log is wound around a core 510. The log can be cut to smaller rolls of any length. The length of the log that is to be cut may be any length. In one embodiment, the length of the log L_logprior to cutting is from about 80 inches to about 120 inches. In another embodiment, the length of the log to be cut is from about 95 inches to about 105 inches.
FIGS. 10A and 10B show an exemplary embodiment of a paper roll 600 that has been cut from the paper log 500 of FIGS. 9A and 9B having the exemplary embossing pattern 400 along lines 550-550 and 560-560 shown in FIGS. 9A and 9B. The paper roll 600 has a surface 610 on which the embossing pattern 400 is disposed and an edge 620 on each of the axial surfaces. In one embodiment, the paper log 500 has been cut such that an edge 620 of the paper roll 600 is tangential to one or more first tracts 441. In another embodiment, the paper log 500 has been cut such that the edge 620 of the paper roll 600 is tangential from about ¼ to about ¾ of the cross machine direction width W_CDof one or more first tracts 441. In another embodiment, the paper log 500 has been cut such that the machine direction edge 620 of the paper roll 600 is tangential from about ⅓ to about ⅔ of the W_CDof one or more first tracts. In another embodiment, the paper log 500 has been cut such that the machine direction edge 620 of the paper roll 600 is tangential from about the midpoint of the W_CDof one or more first tracts 441. In one embodiment, the machine direction edge of the roll exhibits small spaces or gaps 630. The length of the rolls L_rollthat a paper log may be cut into can be any length that is less than the length of the original paper log. In one embodiment, the rolls are from about 3 inches to about 13 inches long. In another embodiment the rolls are from about 4 inches to about 11 inches long.

Embossment Height Test Method

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:

- A) A DMD projector with 1024×768 direct digital controlled micro-mirrors.
- B) CCD camera with high resolution (1300×1000 pixels).
- C) Projection optics adapted to a measuring area of at least 27×22 mm.
- D) Recording optics adapted to a measuring area of at least 27×22 mm; a table tripod based on a small hard stone plate; a cold-light source; a measuring, control, and evaluation computer; measuring, control, and evaluation software, and adjusting probes for lateral (X-Y) and vertical (Z) calibration.
- E) Schott KL1500 LCD cold light source.
- F) Table and tripod based on a small hard stone plate.
- G) Measuring, control and evaluation computer.
- H) Measuring, control and evaluation software ODSCAD 4.0.
- I) Adjusting probes for lateral (x-y) and vertical (z) calibration.

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:

- 1. Turn on the cold-light source. The settings on the cold-light source are set to provide a reading of at least 2,800 k on the display.
- 2. Turn on the computer, monitor, and printer, and open the software.
- 3. Select “Start Measurement” icon from the ODSCAD task bar and then click the “Live Image” button.
- 4. Obtain a fibrous structure sample that is larger than the equipment field of view and conditioned at a temperature of 73° F.±2° F. (about 23° C.±1° C.) and a relative humidity of 50%+2% for 2 hours. Place the sample under the projection head. Position the projection head to be normal to the sample surface.
- 5. Adjust the distance between the sample and the projection head for best focus in the following manner. Turn on the “Show Cross” button. A blue cross should appear on the screen. Click the “Pattern” button repeatedly to project one of the several focusing patterns to aid in achieving the best focus. Select a pattern with a cross hair such as the one with the square. Adjust the focus control until the cross hair is aligned with the blue “cross” on the screen.
- 6. Adjust image brightness by changing the aperture on the lens through the hole in the side of the projector head and/or altering the camera gains setting on the screen. When the illumination is optimum, the red circle at the bottom of the screen labeled “I.O.” will turn green.
- 7. Select technical surface/rough measurement type.
- 8. Click on the “Measure” button. When keeping the sample still in order to avoid blurring of the captured image.
- 9. To move the data into the analysis portion of the software, click on the clipboard/man icon.

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.

EXAMPLE

Cut Along a Second Tract

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 FIGS. 1-6. The rolls are mounted in the apparatus with their respective axes being generally parallel to one another. The rolls are engraved such that the protrusions are in a non-random overall pattern having a multiple repeating pattern of the pattern shown in FIG. 8. The discrete embossing protrusions are frustaconical in shape, with a face (top or distal—i.e. away from the roll from which they protrude) diameter of about 2.79 mm and a floor (bottom or proximal—i.e. closest to the surface of the roll from which they protrude) diameter of about 4.12 mm. The linear protrusions have a width similar to that of the discrete embossing protrusions of about 2.79 mm. The height of the embossing protrusions on each roll is from about 2.718 mm to about 2.845 mm. The planar projected area of each embossing pattern single pattern unit is about 25 cm². The paper described above is fed through the engaged gap at a speed between 300 and 400 meters per minute. The resulting paper has an embossment height of greater than about 1000 μm.
The embossment pattern of the present example invention is that shown in FIGS. 8A and 8B. The first tracts have a percentage unembossed of 0. The second tracts have a percentage unembossed of about 23.8%. The paper log is cut along the second tract and yields a product that has machine direction edges that are highly gapped as shown in FIG. 11A.

EXAMPLE

Cut Along a First Tract

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 FIG. 11B.
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.

Claims

1. 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.

2. The roll paper product according to claim 1 wherein the machine direction edges are tangential from about ¼ to about ¾ of the cross machine direction width of one or more first tracts.

3. The roll paper product according to claim 2 wherein the machine direction edges are tangential from about ⅓ to about ⅔ of the cross machine direction width of one or more first tracts.

4. The roll paper product according to claim 3 wherein the machine direction edges are tangential from about a midpoint of the cross machine direction width of one or more first tracts.

5. The roll paper product according to claim 1 wherein the embossments have a height of from about 650 μm to about 4000 μm.

6. The roll paper product according to claim 5 wherein the embossments have a height of from about 900 μm to about 1800 μm.

7. A roll paper product according to claim 1 wherein a first tract and a second tract further comprises an Unemboss to Emboss factor of from about 1 to about 2.3.

8. A roll paper product according to claim 7 wherein the first tract and the second tract comprises an Unemboss to Emboss factor of from about 1.5 to about 2.

9. A roll paper product according to claim 1 wherein the first tracts have a percent unembossed of from about 0% to about 40%.

10. A roll paper product according to claim 9 wherein the first tracts have a percent unembossed of from about 0% to about 25%.

11. A roll paper product according to claim 1 wherein the roll paper product has a length of from about 3 inches to about 13 inches.

12. A roll paper product according to claim 11 wherein the roll paper product has a length of from about 4 inches to about 11 inches.

13. A roll paper product according to claim 1 wherein the roll paper product is a paper towel product.

14. 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.

15. The method according to claim 14 wherein the paper log is cut such that the machine direction edge is tangential to from about ¼ to about ¾ of the cross machine direction width of the first tract.

16. The method according to claim 15 wherein the paper log is cut such that the machine direction edge is tangential to from about a midpoint of the cross machine direction width of the first tract.

17. The method according to claim 14 wherein the embossments have a height of from about 650 μm to about 4000 μm.

18. The method according to claim 17 wherein the embossments have a height of from about 900 μm to about 1800 μm.

19. The method according to claim 14 wherein the paper log is from about 80 inches to about 120 inches in length.

20. The method according to claim 14 wherein the paper towel rolls are from about 3 inches to about 13 inches in length.

21. 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.