Smooth and bulky rolled tissue products.

ROLLED, SMOOTH AND ROLLED TISSUE PAPER PRODUCTS

BACKGROUND OF THE DESCRIPTION

In the manufacture of tissue paper products such as toilet paper, attention must be paid to a wide variety of product characteristics to provide a final product with the appropriate mix of attributes suitable for the intended purposes of the product. Improving the surface properties of the tissue paper product, such as surface softness, while maintaining the volume of the sheet, is an ongoing goal in the manufacture of tissue paper, especially for premium products. These goals must be further balanced with operational efficiency. One way to balance these properties has been to manufacture the wefts using a through-air drying process. Through air drying provides a relatively uncompressed method of removing water from the weft by passing hot air through the weft until it dries. More specifically, a wet laid weft is transferred from the forming fabric to a thick, highly permeable through air dried fabric and is retained on the through air dried fabric until it is at least almost completely dry. The resulting dry weft is softer and bulkier than a wet-pressed sheet because fewer papermaking bonds are formed and due to

Rsf. 280332 that 1.a. plot is less dense. Squeezing removes water from the wet weft, although subsequent transfer of the weft to a Yankee creping dryer is still often used for final drying and / or softening of the resulting tissue paper.

However, when single sheet tissue paper products are formed into a rolled product, the base sheets tend to lose an appreciable amount of volume due to the compressive forces exerted on the base web during rolling and conversion. As such, there is currently a need for a process to produce a single sheet tissue paper product that has both softness and bulk when spirally wound onto a roll. More particularly, there is a need for a spiral wound product that can maintain a significant amount of roll volume and sheet smoothness even when the product is wound under tension to produce a roll that has the firmness desired by the consumer.

SUMMARY OF THE INVENTION

The present inventors have now discovered an alternative to conventional calendering that results in less loss of sheet volume, while producing a smoother, less stiff tissue paper product that can be converted into a rolled product that has improved firmness in a volume of roll given. Unlike conventional calendering, which employs a pair of substantially smooth stamped opposing rollers, the current invention employs a calender roll comprising male elements and placement areas. Male elements, which can generally be of any shape, have a surface area greater than about 300 mm², such as from about 300 to about 3,000 mm² and more preferably from about 1,750 to about 3,000 mm² and they cover from about 60 to about 98 percent of the roll surface and more preferably from about 70 to 95 percent of the roll surface. Tissue paper products produced through the use of stamping calender rolls have improved properties compared to products produced by conventional calendering.

Accordingly, in one embodiment the present invention provides a wound tissue paper product comprising a calendered tissue paper web wound spirally onto a roll, the product having a roll volume greater than about 15 cc / g, a firmness of the roll of about 5.0 to about 7.0 and a roll structure greater than about 1.80.

In another embodiment the present invention provides a rolled tissue paper product comprising a weft of

<img file="MX369449B_D0001.tif" />

Calendered tissue paper spirally wound on a roll, the product having a roll structure of about 1.80 to about 2.50, the weft having a basis weight of about 35 to about 45 g / m², a surface smoothness less than about 0.260 and a geometric mean tensile (GMT) of about 1,500 to about 3,000 g / 3 (G / 7.62 cm).

In yet another embodiment the present invention provides a smooth, bulky, calendered tissue paper web having a sheet volume greater than about 15 cc / g and surface smoothness less than about 0.260.

In yet another embodiment the present invention provides a stamping calender roll comprising a cylindrical roll having a roll surface comprising placement areas having a first lift and male members having a second lift, where the distance between the first and second elevations (H) is from about 0.30 to about 2.0 mm and the male elements comprise from about 60 to about 95 percent of the total roll surface area.

In another embodiment the present invention provides a method of making a smooth, bulky tissue paper web comprising the steps of providing a tissue paper web, providing a stamping calender roll comprising a cylindrical roll having a roll surface that it includes laying areas that have a first elevation and the male elements that have a second elevation, where the distance between the first and second elevations (H) is from about 0.30 to about 2.0 mm and the male members comprise from about 60 to about 95 percent of the total knee surface area, providing an elastic roll as opposed to the stamp calender and create a calender grip point therebetween, and pass the tissue paper weft through the calender grip point.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a schematic illustration of a useful conversion process for preparing tissue paper products in accordance with an embodiment of the present invention;

Figure 2 is a perspective view of a stamping calender roll in accordance with an embodiment of the present invention; and

Figure 3 is a cross-sectional view through line 2-2 of Figure 2.

DEFINITIONS

As used in the present description, the term gauge is the representative thickness of a single sheet (the gauge of tissue paper products comprising two or more sheets is the thickness of a single sheet of tissue paper product comprising all sheets ) measured according to TAPPI's T402 test method using an automatic Miorogage EMVECO 200-A micrometer (EMVECO, Inc., Newberg, OR). The micrometer has an anvil diameter of 2.22 inches (56.4 mm) and an anvil pressure of 132 grams per square inch (per 6.45 square centimeters) (2.0 kPa). A total of ten sheets of tissue paper product are measured and the total is divided by ten to arrive at the single sheet gauge.

As used herein, the term CD stretching refers to stretching a sample in the cross-machine direction and is an output of the tensile test described in the Test Methods section below.

As used herein, the term basis weight generally refers to the totally dry weight per unit area of ​​tissue paper and is generally expressed in grams per square meter (g / m²). Basis weight is measured using the TAPPI 7-220 test method.

As used herein, the term "firmness" generally refers to Kershaw firmness, which is measured by using the Kershaw test as described in detail in US Patent No. 6,077,590, which is incorporated herein by reference in a manner consistent with the present disclosure. The apparatus is marketed by Kershaw Instrumentation, Inc. (Swedesboro, NJ) and is known as a Model RDT-2GQ2 Roll Density Meter. Firmness generally has units of mm or cm.

As used in the present description, the term geometric mean tensile (GMT) refers to the square root of the product of the machine direction tensile and machine transverse direction of the weft, which are determined as described in the Test Methods section.

As used in the present description, the term layer refers to an element of the discrete product. The individual sheets can be arranged in juxtaposition with each other. The term can refer to a plurality of weft-like components such as on multi-layered facial tissue, toilet tissue, paper towel, wipe, or napkin.

As used in the present description, the term roll volume refers to the volume of the paper divided by its mass in the rolled roll. The volume of the roll is calculated by multiplying pi (3,142) by the amount obtained by calculating the difference in the diameter of the roll squared (which has units of centimeters squared) and the diameter of the outer core squared (which has units of centimeters squared) divided by 4, divided by the amount of the sheet length (which has units of centimeters) multiplied by the sheet count multiplied by the totally dry basis weight of the sheet (which has units of grams per square meter).

As used in the present description, the term roll structure generally refers to the overall appearance and quality of a rolled tissue paper product and is the product of the volume of the roll (having cc / g units) and the gauge ( having units of cm) divided by firmness (having units of cm). In the present description, the structure of the roll is generally mentioned without reference to the units.

As used in the present description, the term "sheet volume" refers to the quotient of the gauge (pm) divided by the totally dry basis weight (g / m²). The volume of the resulting sheet is expressed in cubic centimeters per gram (cc / g).

As used in the present description, the term slope refers to the slope of the line that results from plotting the tensile versus the stretch and is a result of MTS Tesdosrks ™ in the course of determining the tensile strength as described in the Test Methods section. The slope is indicated in units of kilograms (kg) per unit width of the sample (inches) and is measured as the gradient of the least squares line adjusted to the points of deformation corrected for the load that falls between a generated force times the specimen from 70 to 157 grams (0.6 87 to 1.54 0 N) divided by the width of the specimen. Slopes are generally reported in this description as having units of kilograms (kg).

As used in the present description, the term geometric mean slope (GM slope) generally refers to the square root of the product of the slope in the machine direction and the slope in the cross-machine direction. The GM slope is generally expressed in units of kilograms (kg) or grams (g).

As used in the present description, the term stiffness index refers to the quotient of the slope of GM (which has units of grams) divided by the GMT (which has units of g / 3).

As used in this description, the term surface smoothness refers to the average smoothness of the top and bottom surfaces of the tissue paper product and is calculated by averaging the square root of the MIU-CD and MIU-MD product for the surfaces upper and lower. MIU-CD and MIU-MD refers to surface friction in the cross machine direction (CD) and machine direction (MD) or for the bottom or top surface of the tissue paper product measured by using of a KES surface meter (Model KE-SE, Kato Tech Co., Ltd., Kyoto, Japan) as described in the Test Methods section below.

As used herein, the term "tissue paper product" refers to products made from tissue paper wefts and includes, bathroom tissue papers, facial tissue papers, paper towels, industrial wipes, food service cleaners , napkins, medical pads, and other similar products.

As used herein, the terms "tissue paper weft" and "tissue paper sheet" refer to a fibrous sheet-like material suitable for forming a tissue paper product.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a novel tissue paper product that has foil volume and improved surface smoothness that when wound onto a rolled tissue paper product has good roll volume and roll structure. The novel tissue paper products of the present invention are generally produced by calendering tissue paper base sheets through the use of at least one embossing roll. In one embodiment the embossing roll replaces the flat steel roll commonly used in calendering. The elements in the embossing roll provide a means to provide a grip point that has variable loading so that Z-direction variability in the weft is reduced, resulting in a smoother weft, but without subjecting the weft to forces of excessive compression and prevent excessive loss of caliber. Therefore, converted screens according to the present invention tend to retain a higher percentage of their caliber and volume when converted compared to converted screens using conventional calendering means.

Referring to Figure 1, an offline conversion operation 10 is illustrated for converting a tissue paper web 20. Those skilled in the art will appreciate, although the conversion operation 10 is illustrated as offline, it can be applied online. a similar unit operation. The tissue paper weft 20 is unwound from the die roll 40 and transported in sequence to a calendering unit 60. The calendered tissue paper web 26 can then be wound in a rewind unit (not shown). For example, the calendered tissue paper web 26 may be wound onto the cores of tissue paper rolls to form logs, which are subsequently cut to appropriate widths and the resulting tissue paper rolls can then be packed.

The calendering unit 60 includes a pair of calendering rollers 100 and 102 which together define a calendering gripping point 104 therebetween. A separator roll 90 is shown preceding the calendering grip point 104, although other details of the calendering unit 60 are not shown for clarity. In a particularly preferred embodiment the calender unit 60 comprises an embossing roll 100 having elements 110 raised above the surface of the roll 105 and defining a pattern. Embossing roller 100 is shown in opposition to an elastic roller 102 that creates a grip point 104 therebetween. Screen 20, having upper 22 and lower 24 surfaces, passes through grip point 104 and emerges as a calendered screen 26. As illustrated, the bottom surface 24 contacts the embossing roll 100, however, one skilled in the art will appreciate that other configurations are possible. In addition to calendering rollers having different surface patterns, the calendering gripping point can be a soft gripping point where the calendering rollers have different surface hardness.

The elastic calendering may be a smooth coated calender roll. For example, in certain embodiments, the outer surface of the elastic calender roll 102 may include natural rubber, synthetic rubber, composites, as well as other compressible surfaces. A preferred material for the outer surface of the elastic calender roll 102 is ethylene propylene diene polymer. This material is compressible and holds well under pressure. Suitable elastic calender rollers should have a Shore superficial surface hardness of between about 65 to about 100 durometer (about 75 &amp;

<td>approximately</td><td> 0</td><td>Pusey &amp;</td><td colspan="3">Jones, respectively),</td>

<td>preferably</td><td>of</td><td>between</td><td>approximately</td><td> 75</td><td>to</td>

<td>sj and x ί «A 23 Ή βά JL ± i lid LaCÁ 11 IsCr 'J&gt; ¿L * Sur</td><td> 100</td><td>durometer</td><td>(approximately</td><td> 55</td><td>to</td>

<td>approximately</td><td colspan="3">0 Pusey &amp; Jones, respectively)</td><td>, and</td><td>plus</td>

<td>preferably</td><td>of</td><td>between</td><td>approximately</td><td> 85</td><td>to</td>

<td>approximately</td><td> 95</td><td>durometer</td><td>(approximately</td><td> 35</td><td>to</td>

<td>approximately</td><td colspan="2">10 Pusey &amp; Jones</td><td>respectively). AND</td><td>use</td><td>of</td>

An elastic calender roll 102 having an outer surface of ethylene propylene diene polymer with a Shore A surface hardness of about 90 durometer (about 25-30 Pusey &amp; Jones) is particularly suited to the present process.

In opposition to the elastic calender roll 102 is an embossing roll 100. The surface 105 of the embossing roll 100 generally comprises two component elements 110, also referred to as. the present description as male elements, and placement areas 112. Male elements 110 preferably comprise at least about 50 percent of the total area 105 of roll 100, such as from about 50 to about 95 percent and more preferably from about 70 to

<img file="MX369449B_D0002.tif" />

about 90 percent, and even more preferably about 75 to about 90 percent. Male elements 110 can be discrete, as illustrated in Figure 2, or they can be continuous or semi-continuous. As used in the present description, the element pattern is considered discrete if any element does not extend substantially along a major direction of the roll surface. Furthermore, as used in the present disclosure, a boss pattern, the male elements, is considered to be semi-continuous if a plurality of the elements extends substantially along one dimension of the apparatus, and each element in the plurality is separates from an adjacent element.

The elements in the semi-continuous pattern can generally be parallel to each other, they can form a wave pattern, or they can form a pattern in which adjacent elements move relative to each other with respect to the phase of the pattern. The semi-continuous element can be aligned in any direction within the plane of the surface of the embossing roll. Therefore, the element can span the entire machine transverse direction of the roll surface, can endlessly encircle the roll surface in the machine direction, or can be moved diagonally relative to machine and cross directions to the machine.

In other embodiments, the male elements can form a continuous pattern. A continuous pattern extends substantially along both the machine direction and the cross-machine direction of the roll surface, although not necessarily in a straight line manner. Alternatively, a pattern can be continuous because the element structure forms at least one essentially continuous network-like pattern.

Referring to Figure 2, a plan view of a portion of the surface of an illustrative embossing roll 100 is shown. Roll 100 may include a first 111 and a second 113 mounting means for rotatably mounting the roll of calender. The surface 105 of the stamping roll 100 includes a plurality of discrete male elements 110 that are separated by the placement areas 112. Male elements 110 generally comprise a plurality of discrete elements that rise above the surface of placement areas 112 thereby defining a height of element H. In the illustrated embodiment, male elements 110 are uniform and have a generally circular shape, however, the shape of the elements is not limited in this way. In certain embodiments, the male elements may be circular, elliptical, rectangular, rectangular with rounded edges, square, square with rounded edges, trapezoidal, or trapezoidal with rounded edges. Furthermore, although the elements 110 are illustrated as being substantially similar in shape, the invention is not limited in this way and the elements may be of different shapes.

Referring further to Figure 2, in the particular embodiments the male elements 110 protrude from the surface 105 of the stamping roller 100 a height (H), which is measured as the distance between the upper surface 120 of the element 110 and the surface 122 from placement area 112. Generally the top surface 120 of element 110 is substantially flat as illustrated in Figure 3; however, in other embodiments the top surface may have a slight curvature so that the element is convex in cross-sectional shape. In those modalities where the upper surface of the element is convex, the height (H) is measured from the uppermost portion of the surface of the element. Height (H) is generally greater than about 0.20 millimeters (mm). In a particularly preferred embodiment the male elements 110 have a height (H) of from about 0.20 to about 1.5 mm, such as from about 0.30 to about 1.25 mm, and even more preferably from about 0.5 to about 1.00 mm.

As noted above while the elements

110 they are illustrated as having a circular shape, the invention is not limited in this way, and elements 110 can take a variety of shapes. Regardless, discrete elements 110, such as those illustrated in Figures 2 and 3, generally have a length dimension (L) that is measured through the largest width dimension of the top surface 120 of element 110 . The length dimension is generally greater than about 20mm, such as from about 20 to about 100mm and more preferably from about 40 to about 80mm. The upper surface 120 of element 110 generally has a surface area greater than about 300 mm², such as from about 3 00 to about 8,000 mm² and more preferably from about 1,750 to about 3,000 mm².

Elements 110 are generally surrounded by placement areas 112, which are out of plane and generally at a lower elevation after the elements. The distance between adjacent elements (D) may vary depending on the spacing and arrangement of the elements and may not be regular along the surface of the roller. In certain embodiments the distance (D) may be less than about 2 0 mm, such as from about 0.5 to about 2G mm, and more preferably from about 5 to about 10 mm.

The angle of the side wall of the elements, measured relative to the drawn plane tangent to the surface 105 of the embossing roll 100 at the base of the element 110 is suitably between about 90 to about 130 degrees.

Without being bound by any theory, it is believed that the combination of element height, element surface area, and total element coverage area combine to reduce the Z-directional variability of the uncalendered tissue paper weave, making the surface of the tissue paper weave substantially smoother and flatter, while reorienting and reattaching the paper fibers to the surface of the paper weft. All of this is accomplished without a significant reduction in the caliber of tissue paper. As such, the calendering unit of the present invention can be used to make a tissue paper product that is both bulky and smooth. Furthermore, in certain preferred embodiments, preservation of the sheet gauge and smoothness of the sheet surface can be achieved without transmitting a durable image or pattern onto the screen. Therefore, the present invention differs from engraving in that a three-dimensional image or design is not imparted onto the tissue paper web as a result of passing the web through the gripping point created by the opposing calender rolls. Accordingly, in certain embodiments the present invention provides a product of

<img file="MX369449B_D0003.tif" />

Tissue paper has not been etched and has a substantially smooth unprinted surface, most preferably an unengraved through-air-dried tissue paper product and even more preferably an unengraved, un-etched, non-etched, air-dried tissue paper.

The improvement in properties of the finished tissue paper product resulting from the inventive calendering method compared to conventional calendering is illustrated in Table 1, below. A base sheet of single-sheet through-air tissue paper having a basis weight of 38.7 g / m² and a GMT of approximately 2600 g / 3 (G / 7.62 cm) was prepared substantially as described in the Examples, below. The base sheet was subjected to conventional calendering by passing the weft through a fixed gutter calender comprising a smooth steel roll in contact with the air side of the sheet and a 40 P&amp;J polyurethane roll in contact with the side. off the fabric and charged at 40 PLI. The same base sheet was also calendered in accordance with the present disclosure by replacing the smooth steel roll with a calender roll that has male members that cover approximately 75 percent of the surface area of ​​the roll and that has a height of approximately 1.15 tnm .

TABLE 1

<td>Shows</td><td>BW (g / m²)</td><td>Caliber (μπΟ</td><td>Stiffness index</td><td>Foil volume (cc / g)</td><td>Surface smoothness</td><td>Delta surface smoothness (%)</td><td>Delta sheet volume (%)</td><td>Delta stiffness index (%)</td>

<td>Base Sheet</td><td> 38.7</td><td> 1217</td><td> 6.07</td><td> 31.40</td><td> 0.4221</td><td> •</td><td> -</td><td> »</td>

<td>Convinces</td><td> 37.1</td><td> 618</td><td> 5.56</td><td> 16.7</td><td> 0.2882</td><td> -32%</td><td> 47%</td><td> -8%</td>

<td>invention</td><td> 37.3</td><td> 695</td><td> 5.22</td><td> 18.6</td><td> 0.2412</td><td> -43%</td><td> -41%</td><td> -14%</td>

Consequently, the above calendering device can be used to produce tissue paper products that are both bulky and smooth and that have good roll structure when wound on the rolls. Therefore, tissue paper products produced in accordance with the present disclosure have unique properties that represent an improvement over prior art tissue paper rolled products. For example, the present disclosure provides tissue paper products that have comparable or better sheet gauge and sheet volume, while also having good roll volume and roll structure.

TABLE 2

<td>Product</td><td>Prints</td><td>GMT</td><td>Foil volume (cc / g)</td><td>Caliber (um)</td><td>Roll firmness (mtn)</td><td>Roll volume (cc / g)</td><td>Roll structure</td>

<td>Invention</td><td> 1</td><td> 2424</td><td> 18.5</td><td> 695</td><td> 6.2</td><td> 18.5</td><td> 2.08</td>

<td>Scott ™ Towels</td><td> 1</td><td> 2250</td><td> 19.6</td><td> 518</td><td> 6.3</td><td> 17.6</td><td>1.45 I</td>

<td>Scott Naturals ™ Towels</td><td> 1</td><td> 2570</td><td> 20.4</td><td> 536</td><td> 5.9</td><td> 16.8</td><td> 1.53 |</td>

<td>Viva Vantage ™ Towels</td><td> 1</td><td> 2612</td><td> 16.1</td><td> 815</td><td> 5.0</td><td> 13.2</td><td> 2.15 |</td>

<td>Viva ™ Towels</td><td> 1</td><td> 1425</td><td> 12.3</td><td> 650</td><td> 4.6</td><td> 11.3</td><td> 1.60</td>

<td>Bounty Basic ™ Towels</td><td> 1</td><td> 2712</td><td> 19.0</td><td> 706</td><td> 11,9</td><td> 20.4</td><td>L21 j</td>

The tissue paper products of the present invention generally have a basis weight of greater than about 25 g / m.², such as from about 28 to about 50 g / m², more preferably, from about 30 to about 45 g / m², and even more preferably, from about 35 to about 40 g / m². In the above basis weights the products are generally also strong enough to withstand use and therefore preferably have a GMT of greater than about 1,500 g / 3, such as from about 1,500 to about 3,500 g / 3, more preferably of about 1,750 at about 2,750 g / 3, and even more preferably from about 2,000 to about 2,500 g / 3. Accordingly, in certain embodiments, the rolled products manufactured in accordance with the present disclosure may comprise a spirally wound single sheet tissue paper web having a basis weight of from about 30 to about 45 g / m² and a GMT of about 1,750 to about 2,750 g / 3.

Tissue paper products prepared in accordance with the present invention generally retain a larger amount of their gauge after calendering and as such have both improved gauge and sheet volume. As such, in certain embodiments tissue paper products have a gauge greater than about 550 pm, such as from about 550 to about 750 μπι, more preferably from about 600 to about 700 pm, and even more preferably from about 610 to approximately 660 pm. In the above calibers tissue paper products generally have sheet volumes greater than about 16 cc / g, such as from about 16 to about 24 cc / g and more preferably from about 18 to about 22 cc / g.

The spirally wound products preferably have a roll firmness of less than about 8.0 mm, such as from about 4.5 to about 8.0 mm, and more preferably from about 5.0 to about 7.0 mm. At the above levels of firmness the rolled products of the present invention generally have a roll volume of greater than about 15 cc / g, such as from about 15 to about 24 cc / g, more preferably from about 16 to 22 cc / g even more preferably from about 18 to about 20 cc / g. In a particular embodiment, for example, the disclosure provides a rolled tissue paper product comprising a single wound spiral wound sheet paper web having a GMT of from about 1,750 to about 2,750 g / 3, wherein the rolled product it has a roll firmness of about 5.0 to about 7.0 mm and a. volume of

<img file="MX369449B_D0004.tif" />

<td>roll of</td><td>approximately</td><td>16 to 22 cc / g. Inside</td><td>of the</td>

<td>intervals</td><td>previous of</td><td>roll firmness,</td><td>scrolls</td>

<td>manufactured</td><td>in accordance with</td><td>the present description does not</td><td>they look like</td>

<td>be too much</td><td>soft and</td><td>pulpy as it can</td><td>not to be</td>

<td colspan="2">dsSScÜDxG: pd, I? cl ai ^ UHOS Applications.</td><td>consumers during</td><td>some</td>

In the past, at the above roll firmness levels, spiral wound tissue paper products have tended to have low roll volumes and / or poor sheet gauge, resulting in undesirable roll aesthetics. It has now been discovered that a rolled tissue paper product can be produced that retains a greater amount of sheet gauge and volume and is also smooth and not too stiff. As such, rolled tissue paper products prepared in accordance with the present disclosure generally have improved roll structure, such as a roll structure of greater than about 1.5, such as from about 1.5 to about 2.5, more preferably from about 1.8 to about 2.5 and even more preferably from about 2.0 to about 2.5.

In still other embodiments, the present disclosure provides tissue paper wefts that have good tensile properties, are flexible, and not too stiff. As such tissue paper products generally have a CD stretch of greater than about 8.0 percent, such as from about 8.0 to about 12.0 percent, and more preferably from about 10.0 to about 12.0 percent. In other embodiments, tissue paper products have a stiffness index of less than about 8.0, such as from about 4.0 to about 8.0, more preferably from about 4.5 to about 7.0, and even more preferably from about 5.0 to about 6.0.

In addition to the above properties, tissue paper wefts and products produced in accordance with the present invention are generally smoother than wefts and products produced by conventional calendering. As such tissue paper products generally have a surface smoothness less than about 0.260, more preferably less than about 0.240, and even more preferably less than about 0.220, such as from about 0.180 to about 0.260. In other embodiments, in addition to having low surface smoothness, screens and products also have relatively low degrees of HMD, such as an average HMD of less than about 0.020, such as from about 0.014 to about 0.020. The reduction in surface smoothness achieved through the use of the inventive stamping calender roll is typically at least about 5 percent, and more preferably at least about 10 percent, and even more preferably at least about 15 percent, greater compared to conventional calendering of a similar base sheet. Reduction of surface smoothness is generally accomplished without dramatically reducing the volume of the sheet; as such tissue paper wefts and products generally have a sheet volume greater than about 15 cc / g, such as from about 15 to about 20 cc / g and a surface smoothness less than about 0.260 and more preferably less than approximately 0.240.

Screenings useful in the preparation of spiral wound tissue paper products in accordance with the present disclosure may vary depending on the particular application. In general, the wefts can be made from any suitable type of fiber. For example, the base weft can be made from pulp fibers, other natural fibers, synthetic fibers, and the like. Cellulosic fibers suitable for use in connection with this invention include secondary (recycled) papermaking fibers and virgin papermaking fibers in all proportions. Such fibers include, but are not limited to, hardwood and softwood fibers as well as non-woody fibers. Non-cellulosic synthetic fibers can also be included as a portion of the pulp.

Tissue paper webs made in accordance with the present disclosure can be made from a homogeneous fiber pulp or can be formed from a laminated fiber pulp that produces layers within the single sheet product. Layered base frames can be formed by using equipment known in the art, such as a multi-layer input box.

For example, different fiber paper pulps can be used in each layer in order to create a layer with the desired characteristics. For example, layers containing softwood fibers have higher tensile strengths than layers containing hardwood fibers. Hardwood fibers, on the other hand, can increase the softness of the weft. In one embodiment, the single sheet base weft of the present disclosure includes at least one layer containing primarily hardwood fibers. The hardwood fibers can be mixed, if desired, with softwood and / or broken wood fibers in an amount of up to about 40 weight percent and more preferably from about 15 to about 25 weight percent. The base frame further includes an intermediate layer located between the first outer layer and the second outer layer. The intermediate layer may mainly contain softwood fibers. If desired, other fibers, such as high performance fibers or synthetic fibers, can be mixed with the softwood fibers in an amount up to about 10 weight percent.

When a weft is constructed from a layered fiber material, the relative weight of each layer can vary depending on a particular application. For example, in one embodiment, when building a frame containing three layers, each layer may be from about 15 to about 40 percent of the total weight of the frame, such as from about 25 to about 35 percent of the total weight of the plot.

Wet strength resins can be added to the pulp as desired to increase the wet strength of the final product. Currently, the most commonly used wet strength resins belong to the class of polymers called epichlorohydrin polyamide resins. There are many commercial suppliers of these types of resins including Hercules, Inc. (Kymene ™), Henkel Corp. (Fibrabond ™), Borden Chemical (Cascamide ™), Georgia-Pacific Corp., and others. These polymers are characterized by having a polyamide backbone containing reactive crosslinking groups distributed throughout the backbone. Other useful wet strength agents are marketed by American Cyanamid under the tradename Parez ™.

Similarly, dry strength resins can be added to the pulp as desired to increase the dry strength of the final product. Such dry strength resins include, but are not limited to carboxymethyl celluloses (CMCs), any type of starch, starch derivatives, gums, polyacrylamide resins, and others as is well known. Commercial suppliers of such resins are the same as those supplying the wet strength resins discussed above.

Another strength chemical that can be added to pulp is Baystrength 3,000 available from Kemira (Atlanta, GA), which is a glyoxalated cationic polyacrylamide used to impart dry and temporarily wet tensile strength to tissue paper webs.

As described above, the tissue paper products of the present disclosure can generally be formed by any of a variety of papermaking processes known in the art. In one embodiment, the tissue paper weft is formed by a through air drying process without creping. Crepe-free through-air tissue paper processes useful in the practice of the present invention are described, for example, in US Patent Nos. 5,656,132 and 6,017,417, both of which are hereby incorporated by reference in the present disclosure in a manner consistent with the present disclosure.

The forming process of the present disclosure can be any conventional forming process known in the papermaking industry. Forming processes include, but are not limited to, fourdriniers, roof shapers such as suction roll shapers, and gutter shapers such as double tape shapers and croissant shapers. Once formed, the wet tissue paper web is partially dehydrated to a consistency of approximately 10 percent based on the dry weight of the fibers. Further drainage of the wet tissue paper weft can be accomplished by known papermaking techniques, such as vacuum suction boxes, while the interior forming fabric supports the wet tissue paper weft. The wet tissue paper weft can be further dewatered to a consistency of at least about 20 percent, more specifically between about 20 and about 4 0 percent, and more specifically about 20 to about 30 percent.

The forming fabric can generally be made from any suitable porous material, such as metal wires or polymeric filaments. For example, some suitable fabrics may include, but are not limited to, Albany 84M and 94M available from Albany International (Albany, New York); Asten 856, 866, 867, 892, 934, 939, 959, or 937; Asten Synweve Design 274, all of which are marketed by Asten Forming Fabrics, Inc. (Appleton, WI); and Voith 2164 marketed by Voith Fabrics (Appleton, WI). Formation fabrics or felts comprising non-woven base layers may also be useful, including those from Scapa Corporation made from extruded polyurethane foam such as the Spectra Series.

The wet weft is then transferred from the forming fabric to a transfer fabric while having a solids consistency of between about 10 to about 35 percent, and particularly, between about 20 to about 30 percent. As used in the present description, a transfer fabric is a fabric that is placed between the forming section and the drying section of the weft manufacturing process.

Preferably the transfer fabric has a three-dimensional surface topography, which can be provided by substantially continuous machine direction ridges such that the ridges are formed of multiple warp strands grouped together, such as those of U.S. Patent No. . 7,611,607, which is incorporated in the present description consistent with the present description. Particularly preferred fabrics that have a three-dimensional surface topography that may be useful as transfer fabrics include those fabrics described as Fred (tl207 ~ 77), Jetson (t! 207-6) and Jack (tl207-12) in US Patent United no. 7,611,607.

Transfer to the transfer tissue can be carried out with the help of positive and / or negative pressure. For example, in one embodiment, a vacuum shoe can apply negative pressure such that the forming tissue and the transfer tissue simultaneously converge and diverge at the leading edge of the vacuum slot. Typically, the vacuum shoe supplies pressure at levels between about 10 (254 mmHg) to about 25 inches (635 mmHg) of mercury. As indicated above, the vacuum transfer shoe (negative pressure) can be supplied or replaced by the use of positive pressure from the opposite side of the weft to blow the weft onto the next tissue. In some embodiments, other vacuum pads may also be used to aid in stretching the fibrous web over the surface of the transfer tissue.

Typically, the transfer tissue travels at a slower speed than the forming tissue to improve stretch on the MD and CD of the weft, which generally refers to stretching a weft in its cross-machine direction. (CD) or machine direction (MD) (expressed as percentage elongation in the failure of a sample). For example, the relative velocity difference between the two tissues may be approximately JL 0 ex about 35 percent, in some embodiments from about 15 to about 30 percent, and in some embodiments, from about 20 to about 28 percent. This is commonly known as fast transfer. During rapid transfer, many of the weft joints are considered to break, thus forcing the sheet to bend and fold in the depressions on the surface of the transfer fabric 8. Contour molding of the transfer tissue surface can increase the stretch on the MD and CD of the weft. Rapid transfer from one fabric to another can follow the principles taught in any of the following US Patent Nos. 5,667,636, 5,830,321, 4,440,597, 4,551,199, 4,849,054, which incorporate by reference in the present description in a manner consistent with the present description.

The wet tissue paper weft is then transferred from the transfer fabric to a through-air dried fabric. Typically, the transfer fabric travels at approximately the same speed as the through-air dried fabric. The transfer can be carried out with vacuum assistance to ensure the conformation of the wet tissue paper weft to the topography of the through-air dried fabric. While supported by the through-air dried fabric, the wet tissue paper weft is dried to a final consistency of approximately 94 percent or greater by a through dryer. The weft then passes through the winding grip point between the reel drum and reel and is wound onto a roll of tissue paper.

The tissue paper roll is subsequently subjected to calendering as described above. In accordance with the present disclosure, the base weft of the tissue paper product undergoes a calendering process to slightly reduce the gauge of the sheet, increase smoothness, decrease stiffness, while maintaining sufficient tensile strength. The calendering process compresses the weft, effectively breaking some bonds formed between the fibers of the base weft. In this way, calendering can smooth the surface of the sheet and increase the perceived softness of the tissue paper product. Preferably the volume of the tissue paper weft can be largely maintained during calendering. At a minimum, through this process, a greater amount of volume is preserved compared to conventional calendering. This volume of the. Higher foil manifests as higher product roll volume at a fixed firmness while maintaining required foil smoothness.

Surface smoothness

The surface properties of the samples were measured on a KES surface meter (Model KE-SE, Rato Tech Co., Ltd., Kyoto, Japan). For each sample the surface smoothness was measured according to the Kawabata test procedures with the samples tested along the MD and CD and on both sides for five replicates with a sample size of 10 cm x 10 cm. Care was taken to avoid folding, wrinkling, tension, or otherwise handling of the samples in a manner that deforms the sample. Samples were tested using a 10mm x 10mm multi-wire probe consisting of 20 piano wires 0.5mm in diameter each with a contact force of 25 grams. The speed of the test was established at 1 mm / s. The sensor was set to H and FRIC was set to DT. Data was acquired using the KES-FB Measurement Program KES-FB System Ver 7.09 E for Win98 / 2,000 / XP from Kato Tech Co., Ltd., Kyoto, Japan. Selection in the program was KES-SE friction measurement.

The KES surface tester determined the coefficient of friction (MIU) and the mean deviation of MIU (MMD), where

<img file="MX369449B_D0005.tif" />

higher MIU values ​​indicate more friction on the sample surface and higher MMD values ​​indicate more variation or less uniformity on the sample surface.

MIU and MMD values ​​are defined by:

Μΐυ (μ) ^ Υ_χ^ μάχ

MMD = Vi Πμ - 4¿x where ~ friction force divided by compression force ~ mean value of ^x ~ displacement of the probe on the surface of the specimen, cm

X - maximum travel used in the calculation, 2 cm

MIU and MMD values ​​and cross-machine direction (CD) and machine direction (MD) were obtained for both the top and bottom surfaces of each tissue paper product sample. Each sample was tested five times and the results were averaged to arrive at the reported value. For a given area (top or bottom) the valaries of MMD and MIU are reported as the square root of the product of MIU-CD and MIU-MD or MMD-CD and MMD-MD.

To calculate the surface smoothness, the square root of the product of MIÜ-CD and MIU-MD was averaged for the upper and lower surfaces.

Traction

Samples for the tensile strength test are prepared by cutting a 3 (76.2 mm) x 5 (127 mm) long strip in both the machine direction (MD) orientation and the cross-directional direction. machine (CD) by using a JDC Precision Sample Cutter (Thwing-Albert Instrument Company,

Philadelphia, Pennsylvania, Model no. JDC 3-10, no. serial 37333). The instrument used to measure tensile strength is an MTS Systems Sintech 11S, no. 6233 serial. Data collection software is MTS TestWorks ™ for Windows Ver. 4 (MTS Systems Corp., Research Triangle Park, North Carolina). The load cell is selected from 50 Newton or 100 Newton maximum, depending on the resistance of the sample being tested, so that most of the maximum load values ​​fall between 10 and 90 per^- percent of the full scale value of the load cell. The reference length between the clamps is 4 + 0.04 inches (101.6 + 1.01 mm). The clamps are operated through the use of pneumatic action and are rubber coated. The minimum width of the clamping face is 3 (76.2 mm), and the approximate height of a clamp is 0.5 inches (12.7 mm). The crosshead speed is 10 ± 0.4 inches / min (254 + 1 mm / min), and the breaking sensitivity is set to 65 percent. The sample is placed in the instrument clamps, both centered vertically and horizontally. The test then begins and ends when the specimen breaks. The maximum load is recorded as the tensile strength in the MD or the tensile strength in the CD of the specimen depending on the sample to be tested. At least six representative specimens are tested for each product, taken as is, and the arithmetic average of all tests on the individual specimens is the tensile strength in either the MD or CD for the product.

EXAMPLES

The base sheets were manufactured using a through-air drying papermaking process commonly referred to as crepe-free through-air drying (UCTAD) and generally described in U.S. Patent No. 5,607,551, the content of which is incorporated in the present description in a manner consistent with the present invention. Base sheets were produced with a target totally dry basis weight of approximately 38 grams per square meter (g / m²). The base sheets were then converted and spirally folded to produce rolled tissue paper products.

In all cases the base sheets were produced from a pulp comprising Northern Softwood Kraft (NSWK) and Eucalyptus Kraft (EHWK) using a layered inlet box fed by three mixing tanks of so that frames having three layers (two outer layers and one intermediate layer) were formed. The tissue paper weft was formed on a Voith Fabrics TissueForm V forming fabric, vacuum drained to approximately 25 percent consistency, and then subjected to rapid transfer when transferred to the transfer tissue. The layer divisions, by weight of the weft, were 30% by weight of EHWK / 40% by weight of NSWK / 30% by weight of EHWK. Strength was controlled by adding CMC, Kymene and / or by refining the NSWK pulp of the core layer.

The wet tissue paper weft was transferred to a transfer fabric designated as Fred, previously described in US Patent No. 7,611,607 and marketed by Voith Fabrics, Appleton, WI. The weft was then transferred to a through-air dried fabric designated t-1205-2, described above in US Patent No. 8,500,955 and marketed by Voith Fabrics, Appleton, WI. Transfer to the through-air dried fabric was performed using vacuum levels of more than 10 inches of mercury in the transfer. The weft was then dried to approximately 98 percent solids prior to

<img file="MX369449B_D0006.tif" />

curl.

The base sheet wefts were converted into various rolled towels. Specifically, the base sheet was calendered by using both a conventional 5-polyurethane / steel calender comprising a 40 P&amp;J polyurethane roll on the air side of the sheet and a standard steel roll on the fabric side to a 4 0 PLI load, or a stamped polyurethane / steel calender comprising a 40 P&amp;J polyurethane roll on the air side of the sheet and a stamped steel roll on the fabric side at a load of 40 PLI. The process conditions for each sample are provided in Table 3, below. All rolled products comprised a single sheet of base sheet.

TABLE 3

<td>Shows</td><td>Calender load (fold)</td><td>Male element height (mm)</td><td>Surface area of ​​the male element of the stamping roller (% of surface area of ​​the roll)</td>

<td>Control</td><td> 40</td><td></td><td> ··</td>

<td>Roll 1</td><td> 40</td><td> 1.145</td><td> 90</td>

<td>Roll 2</td><td> 40</td><td> 0.40</td><td> 90</td>

<td>Roll 3</td><td> 40</td><td> 1.145</td><td> 75</td>

<td>Roll 4</td><td> 40</td><td> 0.40</td><td> 75</td>

<img file="MX369449B_D0007.tif" />

TABLE 4

<td>Shows</td><td>Base weight (g / m²)</td><td>Caliber (microns)</td><td>Foil volume (cc / g)</td><td>GMT (g / 3 ")</td><td>Stretch in the CD (%)</td><td>Slope of GM (kg)</td><td>Stiffness index.</td>

<td>Control</td><td> 37.1</td><td> 618</td><td> 16.7 1</td><td> 2251</td><td> 9.6</td><td> 12.51</td><td> 5.56</td>

<td>Roll 1</td><td> 37.5</td><td> 648</td><td>17.3 i</td><td> 2360</td><td> 10.1</td><td> 12.27</td><td> 5.20</td>

<td>Roll 2</td><td> 37.6</td><td> 638</td><td> 16.9 1</td><td> 2362</td><td> 9.7</td><td> 13.07</td><td> 5.53</td>

<td>Roll 3</td><td> 37.3</td><td> 695</td><td> 18.6 |</td><td> 2424</td><td> 9.9</td><td> 12.66</td><td> 5.22</td>

<td>Roll 4</td><td> 37.6</td><td> 666</td><td> 17.7 |</td><td> 2340</td><td> 10.1</td><td> 12.35</td><td> 5.28</td>

TABLE 5

<td>Shows</td><td>Roll firmness (mm)</td><td>Roll volume (cc / g)</td><td>Roll structure</td><td>Upper surface MIU</td><td>Bottom surface MIU</td><td>Surface smoothness</td><td>Average MMD</td>

<td>Control</td><td> 5.7</td><td> 16.4</td><td> 1.77</td><td> 0.3074</td><td> 0.2688</td><td> 0.2882</td><td> 0.0223</td>

<td>Roll 1</td><td> 6.1</td><td> 17.6</td><td> 1.86</td><td> 0.2627</td><td> 0.2330</td><td> 0.2478</td><td> 0.0204</td>

<td>Roll 2</td><td> 5.6</td><td> 16.6</td><td> 1.90</td><td> 0.2372</td><td> 0.2286</td><td> 0.2418</td><td> 0.0196</td>

<td>Roll 3</td><td> 6.2</td><td> 18.5</td><td> 2.08</td><td> 0.2554</td><td> 0.2280</td><td> 0.2412</td><td> 0.0194</td>

<td>Roll 4</td><td> 5.2</td><td> 17.7</td><td> 2.28</td><td> 0.2662</td><td> 0.2161</td><td> 0.2326</td><td> 0.0179</td>

While the invention has been described in detail with respect to the foregoing description and examples, the following embodiments, as well as equivalents thereof, are within the scope of the invention. Accordingly, in a first embodiment the present invention provides a rolled tissue paper product comprising a calendered tissue paper web wound spirally onto a roll, the product having a roll volume greater than about 15 cc / g, a firmness roll stock from about 5.0 to about 7.0 and a roll structure greater than about 1.80.

In a second embodiment the present invention provides the rolled tissue product of the first embodiment having a surface smoothness of less than about 0.260, such as from about 0.200 to about 0.260.

In a third embodiment the present invention provides the first or second embodiment rolled tissue paper product having a sheet volume greater than about 15 cc / g, such as from about 15 to about 20 cc / g.

In the fourth embodiment the present invention provides the rolled tissue paper product of any of the first to the third embodiment having a GMT greater than about 1,750 g / 3 (g / 7.62 cm), such as from about 1,750 to about 3,000 g /3.

In a fifth embodiment, the present invention provides the rolled tissue paper product of any of the first to the fourth modalities having a CD stretch greater than about 8 percent, such as from about 8 to about 12 percent.

In a sixth embodiment the present invention provides the rolled tissue paper product of any of the first to the fifth embodiment having a slope

<img file="MX369449B_D0008.tif" />

GM less than about 15 kg, such as from about 10 to about 15 kg, and a stiffness index of less than about 7, such as from about 5 to about 7.

In a seventh embodiment, the present invention provides the rolled tissue paper product of any of the first to sixth modalities having a gauge greater than about 640 µτη, such as from about 640 to about 700 pm.

In an eighth embodiment the present invention provides a smooth, bulky, calendered tissue paper web having a sheet volume greater than about 15 cc / g and surface smoothness less than about 0.260.

In a ninth embodiment the present invention provides the screen of the eighth embodiment having a sheet volume greater than about 15 cc / g, such as from about 15 to about 20 cc / g.

In a tenth embodiment the present invention provides the eighth or ninth embodiment having a GMT greater than about 1,750 g / 3 (g / 7.62 cm), such as from about 1,750 to about 3,000 g / 3 (g / 7.62 cm).

In an eleventh embodiment the present invention provides the screen of any of the eighth to the tenth modalities having a stretch in the CD greater than about 8 percent, such as from about 8 to about 12 percent.

In a twelfth embodiment the present invention provides the rolled tissue paper product of any of the eighth to the eleventh modalities having a slope of GM less than about 15 kg, such as from about 10 to about 15 kg and a less rigid index. from about 7, such as from about 5 to about 7.

In a thirteenth embodiment the present invention provides the rolled tissue paper product of any of the eighth to the twelfth modalities wherein the tissue paper weft is a through-air dried weft without creping and has not been etched.

It is noted that in relation to this date, the best method known by the applicant to put the aforementioned invention into practice is the one that is clear from the present description of the invention.