Embossed multi-layer tissue paper products

Abstract

The present invention provides an embossed multi-ply tissue paper product that is visually pleasing and has improved physical properties. For example, the multi-ply tissue paper product of the present invention has reduced stiffness, such as GM flexural rigidity less than about 600 mg*cm, improved absorbency, such as residual water (W 残留 ) value is less than about 0.15 g, and improved wet resilience, for example, a wet elastic strain ratio greater than about 32%.

Description

Background Art

[0001] In the manufacture of paper products, especially tissue products such as facial tissue, toilet tissue, paper towels, napkins, etc., a wide variety of product properties must be considered in order to provide a final product having an appropriate blend of properties suitable for the intended purpose of the product. Among these various properties, improving strength, absorbency, thickness, and wet resilience have been the main goals.

[0002] Traditionally, many of these paper products have been made using a wet-pressing process in which a large amount of water is removed from a wet-laid web by pressing or squeezing the water out of the web prior to final drying. Specifically, when supported by an absorbent papermaking felt, a pressure roll is used to press the web between the felt and the surface of a rotating heated cylinder (Yankee dryer) as the web is conveyed to the surface of a Yankee dryer. The web is then removed from the Yankee dryer (creped) with a doctor blade that partially debonds the web by breaking many of the bonds previously formed during the wet-pressing stage of the process. The web may be dry-creped or wet-creped. Creping generally improves the softness of the web, but at the expense of a significant loss of strength.

[0003] Recently, through-air drying has become a more common method of drying webs. Through-air drying provides a relatively non-compressive method of removing water from a web by passing hot air through the web until it is dry. More specifically, a wet-laid web is transferred from a forming fabric to a coarse, high-permeability through-air drying fabric and remains on the through-air drying fabric until it is dry. The resulting dry web is softer and more bulky than a conventionally dried, uncreped sheet because fewer bonds are formed and because the web is less compressed. Although pressure rolls may still be used to subsequently transfer the web to a Yankee dryer for creping, squeezing water from the wet web is eliminated.

[0004] While through-air drying can improve the softness and bulk of a web, it is often necessary to subsequently convert the web to further increase bulk and impart aesthetic qualities to the web. To this end, single-ply and multi-ply webs are embossed. In a typical embossing process, a web substrate is fed through a nip formed between juxtaposed, generally parallel rollers. Embossing elements on the rollers compress and / or deform the web. If a multi-ply product is formed, two or more plies are fed through the nip, and areas of each ply are brought into contacting relationship with an opposing ply. The embossed areas of the plies can produce an aesthetically pleasing pattern, provide a means for joining and holding the plies in face-to-face contact, and can increase the bulk of the product.

[0005] Consumers generally desire embossed products with relatively high bulk and aesthetically pleasing decorative patterns with a cloth-like appearance. These attributes must be balanced with other product properties such as softness, which can be measured in terms of stiffness, wet resilience and absorbency.

[0006]

[0006] Therefore, there remains a need in the art for an embossed tissue product that is more aesthetically pleasing while providing important product properties such as reduced stiffness, improved wet resiliency, and increased absorbency. Summary of the invention

[0007] The inventors have now discovered that various tissue manufacturing techniques, such as embossing and wet molding, can be used to produce multi-ply tissue products that are both aesthetically pleasing and have improved physical properties. For example, the present invention provides a tissue product that is made by a process such as through-air drying, which provides a web with a first pattern, and is combined with another web and embossed to provide a second pattern. The tissue product of the present invention has reduced stiffness, such as a GM flexural rigidity of less than about 600 mg*cm, improved absorbency, such as residual water (W 残留 ) value is less than about 0.15 g, and improved wet resilience, for example, a wet elastic strain ratio greater than about 32%.

[0008] Thus, in one embodiment, the present invention provides an embossed multi-ply tissue paper product comprising a first outer surface, an opposing second outer surface, and a plurality of embossments disposed on at least the first outer surface, wherein the product has a drip time (DT) greater than about 30 seconds, more preferably greater than about 40 seconds, still more preferably greater than about 45 seconds, and even more preferably greater than 60 seconds.

[0009] In another embodiment, the present invention provides a drip-free tissue paper product comprising a first tissue paper ply and a second tissue paper ply, wherein the first tissue paper ply has a first upper surface and a plurality of embossments disposed thereon, the tissue paper product having a fluid discharge weight (WD) of less than 0.15 g.

[0010] In another embodiment, the present invention provides an embossed multi-ply tissue product having a first outer surface and an opposing second outer surface, the product comprising a first through-air dried tissue ply and a second through-air dried tissue ply, the first through-air dried tissue ply having a first surface, the first surface forming a first outer surface of the product and comprising a background pattern and a first embossed pattern, the first embossed pattern comprising discrete non-linear line elements, wherein the embossed pattern covers from about 5.0% to about 10.0% of the first outer surface of the tissue product, the product having a basis weight of from about 50 gsm to about 60 gsm, a GMT of from about 3,000 g / 3" to about 4,000 g / 3", and a drip time (DT) greater than about 30 seconds.

[0011] In another embodiment of the present invention, an embossed multi-ply tissue product is provided, comprising two or more plies bonded together in a face-to-face manner, wherein at least one of the plies comprises a plurality of line embossments arranged in an embossing pattern, wherein the embossing pattern covers less than about 10% of the surface area of ​​the ply. In certain preferred embodiments, the embossing pattern comprises discrete nonlinear line elements. In other embodiments, at least about 90%, more preferably at least about 95%, of the embossed area is composed of line elements having a length greater than about 20.0 mm, such as from about 20.0 to about 60.0 mm. In other embodiments, only one of the tissue plies comprises embossing, and in other embodiments, the embossed tissue ply is substantially free of point embossing.

[0012] In another embodiment, the present invention provides a method of making an embossed multi-ply fibrous structure, the method comprising the steps of: (a) providing a first tissue ply; (b) embossing a first embossing pattern on the first ply by passing the first ply through an embossing nip, wherein the embossing area is less than about 10%; (c) providing a second tissue ply; (d) applying an adhesive to at least one of the tissue plies; and (e) bonding the first tissue ply and the second tissue ply together in a face-to-face relationship. In certain embodiments, the embossing pattern comprises discrete nonlinear line elements having a diameter greater than about 20.0 mm, such as about 20.0 to about 50.0 mm, for example about 25.0 to about 40.0 mm. In other embodiments, the second ply is unembossed. In other embodiments, the first and second tissue plies are through-air dried and may be creped or uncreped and may have a background pattern consisting essentially of thread elements that are the result of wet molding of the tissue plies. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1A is a schematic diagram of an embossing method for preparing a product according to the present invention, and Figure 1B An embossed tissue paper product produced by the method is shown;

[0014] Figure 2 An embossing pattern that can be used in the present invention is shown;

[0015] Figure 3 is a perspective view of a tissue paper product;

[0016] Figure 4 is a top plan view of a tissue paper product;

[0017] Figure 5A and 5Bis a 3-D image and cross-sectional profile of a tissue paper product obtained using a Keyence microscope and imaging software as described herein

[0018] Figure 5C shows a cross section of a tissue paper product;

[0019] Figure 6 An embossing pattern useful in making a tissue paper product according to the present invention is shown; and

[0020] Figure 7 Another embossing pattern useful in making a tissue paper product according to the present invention is shown.

[0021] definition

[0022] As used herein, "tissue paper products" generally refer to various paper products, such as facial tissue, toilet tissue, paper towels, napkins, etc. Typically, the basis weight of the tissue paper products of the present invention is greater than about 40 grams per square meter (gsm), more preferably greater than about 45 gsm, and even more preferably greater than about 50 gsm, for example, from about 45 gsm to about 65 gsm, and more preferably from about 50 gsm to about 60 gsm.

[0023] As used herein, the term "basis weight" generally refers to the water-free dry weight per unit area of ​​tissue paper and is generally expressed in grams per square meter (gsm). Basis weight is measured using TAPPI Test Method T-220.

[0024] The term "ply" refers to a discrete product element. Individual plies may be arranged juxtaposed to one another. The term may refer to a plurality of web-like components, such as in a multi-ply facial tissue, multi-ply toilet tissue, multi-ply paper towel, multi-ply wipes or multi-ply napkins, which may include two, three, four or more single plies arranged juxtaposed to one another, wherein one or more plies may be attached to one another, such as by mechanical or chemical methods.

[0025] As used herein, the term "layer" refers to the multiple fiber layerings, chemical treatment layerings, etc. within a ply.

[0026] As used herein, the terms "layered tissue web", "multi-layer tissue web", "multi-layer web" and "multi-layer paper sheet" generally refer to a paper sheet prepared from two or more layers of aqueous papermaking furnish, preferably comprising different fiber types. The layers are preferably deposited from separate streams of dilute fiber slurry on one or more endless porous screens. If the individual layers are initially formed on separate porous screens, the layers are subsequently combined (while wet) to form a stratified composite web.

[0027] As used herein, the term "machine direction" (MD) generally refers to the direction in which a tissue web or product is produced. The term "cross direction" CD refers to the direction perpendicular to the machine direction.

[0028] As used herein, the term "caliper" is the representative thickness of a single sheet (the thickness of a tissue product including one or more plies is the thickness of a single sheet of tissue product including all plies) measured in accordance with TAPPI Test Method T402 using a ProGage 500 Thickness Tester (Thwing-Albert Instrument Company, West Berlin, NJ). The micrometer has an anvil diameter of 2.22 inches (56.4 mm) and an anvil pressure of 132 grams per square inch (6.45 grams per square centimeter) (2.0 kPa).

[0029] As used herein, the term "sheet bulk" refers to the quotient of thickness (μm) divided by the water-free dry basis weight (usually expressed in grams per square meter (gsm)). The resulting sheet bulk is expressed in cubic centimeters per gram (cc / g). In certain embodiments, the tissue paper products prepared according to the present invention can have a sheet bulk of greater than about 12cc / g, more preferably greater than about 15cc / g, and even more preferably greater than about 17cc / g, such as from about 12 to about 20cc / g.

[0030] As used herein, the term "slope" refers to the slope of a line obtained by plotting stretch versus stretch and is the slope of the MTS TestWorks TM Output in the process of determining tensile strength as described in the Test Methods section of this document. The slope is reported in grams (g) per unit sample width (inch) and is measured as the gradient of the least squares line fit to the load-corrected strain points falling between 70 grams and 157 grams (0.687N to 1.540N) of the sample generated force divided by the sample width.

[0031] As used herein, the term "geometric mean slope" (GM slope) generally refers to the root mean square of the product of the machine direction slope and the cross direction slope. Although the GM slope may vary between tissue products prepared according to the present disclosure, in certain embodiments, the tissue product has a GM slope of less than about 14,000 g, more preferably less than about 13,500 g, and even more preferably less than about 13,000 g, such as from about 9,000 to about 14,000 g.

[0032] As used herein, the term "geometric mean tensile" (GMT) refers to the square root of the product of the machine direction tensile strength and the cross direction tensile strength of the web. Although the GMT may vary, in certain embodiments, tissue products prepared according to the present disclosure may have a GMT greater than about 1,500 g / 3", and more preferably greater than about 1,750 g / 3", and even more preferably greater than about 2,000 g / 3", such as from about 1,500 to about 4,000 g / 3", such as from about 2,000 to about 3,500 g / 3".

[0033] As used herein, the term "Stiffness Index" refers to the quotient of the geometric mean tensile slope, which is defined as the square root of the product of the MD and CD slopes (usually in kg), divided by the geometric mean tensile strength (usually in grams per three inches).

[0034]

[0035] Although the Stiffness Index may vary, in certain embodiments, tissue paper products prepared according to the present disclosure can have a Stiffness Index of less than about 6.00, more preferably less than about 5.00, and still more preferably less than about 4.00, such as from about 3.00 to about 6.00, such as from about 3.50 to about 4.50.

[0036] As used herein, the term "stretch ratio" generally refers to the ratio of machine direction (MD) stretch (in g / 3") to cross direction (CD) stretch (in g / 3"). Although the stretch ratio may vary, in certain embodiments, tissue products prepared according to the present disclosure may have a stretch ratio of less than about 2.0, such as from about 1.0 to about 2.0, such as from about 1.2 to about 1.5.

[0037] As used herein, the term "wet elastic strain ratio" is the elastic strain ratio when a wet sheet is compressed to 300 g / in 2 (4569Pa), measured according to the Wet Resilience Test Method described in the Test Methods section below, to the ratio of the elastic strain to the applied strain. The Wet Elastic Strain Ratio is equal to:

[0038]

[0039] C15 is 5g / in before the first compression cycle 2 In the case of a sheet thickness of 0.1 mm (also referred to herein as initial wet thickness), C1 300 300 g / in in the first compression cycle 2 (4569Pa) load, and C25 is 5g / in in the second compression cycle 2 The sheet thickness (just loaded to 300g / in in the first cycle) 2 After that). When measuring the elastic strain ratio, the thickness usually has units of millimeters (mm). The range of the wet elastic strain ratio will be between the wet elastic strain ratio of a perfectly elastic solid with no plastic deformation and the wet elastic strain ratio of zero for a perfectly plastic solid with no elastic recovery.

[0040] As used herein, the term "geometric mean flexural stiffness" (GM flexural stiffness) generally refers to the relative stiffness of a tissue product or web and is measured in accordance with ASTM D1388, as described in the Test Methods section below. GM flexural stiffness is generally measured in mg*cm2 The unit is / cm.

[0041] The term "residual water" (W 残留 ) refers to the mass of water not initially absorbed by the tissue paper sample, as measured according to the Drip Test described in the Test Methods section below. Residual Water generally has units of grams (g).

[0042] As used herein, the term "drip time" (DT) refers to the time required for a wetted tissue paper sample to drip, and is measured according to the Drip Test described in the Test Methods section below. Drip time is typically measured in seconds (s).

[0043] As used herein, the term "water retention" (Wretention) refers to the mass of water retained by a sample at the end of a drip test as described in the Test Methods section below. The water retained typically has units of grams (g).

[0044] As used herein, the term "line element" refers to an element in the shape of a line, such as an embossed element, which can be continuous, discrete, discontinuous and / or partial lines relative to the tissue paper product in which it is located. The line element can have any suitable shape, such as straight, bent, kinked, curled, curved, meandering, sinusoidal, and mixtures thereof, which can form a regular or irregular, periodic or non-periodic lattice configuration of the structure, wherein the line element presents a length of at least 20 mm along its path. In one example, the line element may include a plurality of discrete elements, such as dots and / or dashed lines, which are oriented together to form the line element.

[0045] As used herein, the term "non-linear element" refers to a multi-directional, uninterrupted portion of an element having a length (L). In some cases, the length may be about 20.0 mm or greater. The length (L) of an element is typically measured along an uninterrupted portion of the element, such as from Figure 2 From point A to point B. In one example, for example Figure 2 As shown, the nonlinear element 80 may include a first unidirectional uninterrupted linear element segment 84 and a second unidirectional uninterrupted linear element segment 86. The nonlinear element is generally disposed on the surface of a tissue paper product and may be produced by embossing the product. In certain preferred embodiments, for example Figure 3 As shown, the tissue product 60 may include substantially identical, discrete, non-linear embossed elements 80 that form a pattern 94 to form a pattern 90 having a primary axis 92 of orientation of the pattern.

[0046] As used herein, the term "multi-directional" when referring to an element such as a non-linear embossed element means that the element has at least a first directional vector and a second directional vector. Figure 2, the nonlinear element 80 has a first segment 84 having a first direction vector 85 extending in a first direction, and a second segment 86 having a second direction vector 87 extending in a second direction different from the direction of the first direction vector 85 .

[0047] As used herein, the term "discrete" when referring to an element such as a nonlinear embossed element means that the nonlinear element has at least one immediately adjacent region of the tissue product that is different from the nonlinear element. Figure 3 , the embossed pattern 90 includes a plurality of embossed non-linear elements, such as elements 80a and 80b, which are separated from each other by unembossed areas 89 of the tissue product 60.

[0048] As used herein, the term "uninterrupted" when referring to an element, such as a nonlinear embossed element, means that along the length of a given nonlinear element, the nonlinear element does not intersect with regions other than the nonlinear element. Variations in the plies of tissue within a given nonlinear element, such as variations produced by manufacturing processes such as forming, molding, or creping, are not considered to produce regions other than the nonlinear element and, therefore, do not interrupt the nonlinear element along its length.

[0049] As used herein, the term "substantially machine directionally oriented" when referring to elements, such as non-linear elements, embossed patterns, or background patterns, disposed on the surface of a tissue paper layer or product generally means that the primary orientation axis of the element is positioned at an angle greater than about 45 degrees to the cross-machine direction (CD) axis.

[0050] As used herein, the term "pattern" generally refers to an arrangement of one or more design elements. Within a given pattern, the design elements may be the same or may be different, and further, the design elements may have the same relative size or may have different sizes. For example, in one embodiment, a single design element may be repeated in a pattern, but the size of the design element may vary from one design element to the next within the pattern.

[0051] As used herein, the term "pattern" generally refers to the non-random recurrence of one or more embossed elements within an embossed pattern. The recurrence of an element does not necessarily occur within a given sheet, for example, in certain embodiments, a design element may be a continuous element extending across two adjacent sheets separated from each other by a perforation line. Figure 2 The embossed pattern 90 includes a pattern 94 composed of three discrete non-linear units 80a, 80b, 80c.

[0052] As used herein, the term "background pattern" refers to a pattern that substantially covers the surface of a tissue paper product. Those skilled in the art will appreciate that a background pattern can be distinguished from a repeating pattern because a repeating pattern can include multiple segment patterns, segment axes, and units, while in some embodiments, a background pattern can include only a single feature that repeats at any frequency and / or interval. In other embodiments, a background pattern includes multiple features that may form a repeating unit. A repeating unit may be described as a design that includes multiples of one or more base patterns.

[0053] The background pattern can be formed using any method known in the art. For example, in some embodiments, embossing or micro-embossing can be used to introduce the background pattern into the surface of the tissue paper product. For example, exemplary embodiments of micro-embossing are described in U.S. Publication No. 2005 / 0230069. In other embodiments, during the papermaking process, a textured or patterned papermaking fabric, such as described in U.S. Patent No. 7,611,607, can be used to introduce the background pattern into the surface of the tissue paper sheet or product.

[0054] As used herein, the term "embossing" in reference to a tissue paper product means that during the manufacturing process, one or more of the tissue paper plies comprising the product have been subjected to a process that transforms a smooth-surfaced tissue paper web into a decorative surface by replicating an embossing pattern on one or more embossing rolls that form a nip through which the tissue paper web passes. Embossing does not include wet molding, creping, micro-creping, printing or other methods that can impart texture and / or decorative patterns to a tissue paper web.

[0055] As used herein, the term "embossing pattern" generally refers to the arrangement of one or more design elements in at least one dimension of the surface of a tissue product, the design elements being imparted by embossing the tissue product. The pattern may include linear elements, non-linear elements, discrete non-linear elements, or other shapes. The embossing pattern includes a portion of the tissue product that is located outside the surface plane of the tissue product. Typically, the embossing pattern is produced by embossing the tissue product to produce a recessed area having a z-direction height below the surface plane of the tissue product. The recessed area may suitably be one or more linear elements, discrete elements, or other shapes.

[0056] As used herein, the term "embossing plane" generally refers to the plane formed by the upper surface of the recessed portions forming the embossed tissue product. Typically, the embossing element plane is located below the surface plane of the tissue product. In certain embodiments, the tissue products of the present invention may have a single embossing element plane, while in other embodiments, the structure may have multiple embossing element planes. The embossing element plane is generally determined by imaging a cross-section of the tissue product and drawing a line tangent to the uppermost surface of the embossing, wherein the line is generally parallel to the x-axis of the tissue product.

[0057] As used herein, the term "embossed area" generally refers to the percentage of the tissue product surface area covered by embossments as measured using a Keyence VHX-5000 digital microscope (Keyence Corporation, Osaka, Japan) and described in the Test Methods section below. DETAILED DESCRIPTION

[0058] The inventors have successfully balanced the manufacture of molded three-dimensional tissue sheets with embossing and lamination to form a multi-ply tissue product that is visually pleasing and has improved physical properties. For example, the multi-ply tissue product of the present invention has reduced stiffness, such as GM flexural rigidity less than about 600 mg*cm, improved absorbency, such as residual water (W 残留 ) value is less than about 0.15g, and improved wet resilience, such as a wet elastic strain ratio of greater than about 32%. In some cases, the improvement in physical properties is accompanied by an improvement in the aesthetic appeal of the product, such as a multi-ply tissue product having a first pattern and a second pattern, wherein the first pattern is embossed and the second pattern is not embossed. The first embossed pattern may cover a relatively small percentage of the total surface area of ​​the tissue product, such as less than about 15%, more preferably less than about 10%. In addition, the embossed pattern may include discrete non-linear thread elements that are visually attractive to consumers, especially when the thread elements are arranged in a geometric pattern that gives the product a cloth-like appearance.

[0059] Thus, in certain embodiments, the present invention provides an embossed multi-ply tissue product comprising two or more tissue plies having a background pattern imparted by wet molding of the sheet during manufacture and a total embossed area of ​​less than about 15% or less, such as less than about 12%, more preferably less than about 10%, such as from about 5% to about 15%, and having improved stiffness, wet resilience and absorbency compared to the prior art. In some cases, the background pattern may include a plurality of parallel, equally spaced thread elements interrupted by an embossed pattern that also includes non-linear thread elements.

[0060] In other embodiments, the present invention provides an embossed multi-ply tissue product comprising two or more plies bonded together in a face-to-face relationship, wherein at least one of the plies comprises a background pattern and a plurality of line embossments arranged in an embossed pattern. Preferably, the background pattern is not embossed and the embossed area is less than about 15%, more preferably less than about 10%. The resulting tissue product generally has improved stiffness, wet resilience and absorbency over the prior art.

[0061] The multi-ply embossed tissue products of the present invention typically include two, three or four tissue plies made by a known wet papermaking process, such as creped wet pressing, modified wet pressing, creped through air drying (CTAD) or uncreped through air drying (UCTAD). For example, a creped tissue web can be formed using a wet pressing or modified wet pressing process, such as those disclosed in U.S. Pat. Nos. 3,953,638, 5,324,575 and 6,080,279, the disclosures of which are incorporated herein in a manner consistent with the present application. In these processes, the embryonic tissue web is transferred to a Yankee dryer, dried, and then creped from the Yankee dryer surface using a doctor blade or other suitable device.

[0062] In a particularly preferred embodiment, one or more tissue plies may be made by a through-air drying process. In such a process, the embryonic web is dried non-compressively. For example, the tissue plies used in the present invention may be formed by a creped or uncreped through-air drying process. Particularly preferred are uncreped through-air dried webs, such as those described in U.S. Pat. No. 5,779,860, the contents of which are incorporated herein in a manner consistent with the present disclosure.

[0063] In other embodiments, one or more tissue plies may be made by a process comprising the steps of: using pressure, vacuum, or air flow through a wet web (or a combination of these) to conform the wet web to a forming fabric, followed by drying the formed web using a Yankee dryer or a series of steam heated dryers or some other device, including but not limited to tissue made using the ATMOS process developed by Voith or the NTT process developed by Metso; or fabric-creped tissue, which is made using a process comprising the steps of transferring the wet web from a transport surface (belt, fabric, felt, or roll) moving at one speed to a fabric moving at a slower speed (at least 5% slower) and then drying the paper. Those skilled in the art will recognize that these processes are not mutually exclusive, for example, in this process, an uncreped TAD process may include a fabric-creping step.

[0064] The multi-ply tissue product of the present invention may be composed of two or more plies manufactured using the same or different tissue manufacturing techniques. In a particularly preferred embodiment, the multi-ply tissue product comprises two through-air dried tissue plies, wherein each ply has a basis weight greater than about 20 gsm, such as from about 20 to about 50 gsm, such as from about 22 to about 30 gsm, wherein the plies have been attached to each other by a glue lamination and embossing process that provides an embossed pattern on at least one outer surface of the tissue product. Certain aspects of the embossed pattern will be discussed in more detail below.

[0065] In some cases, tissue products are manufactured using papermaking fabrics, such as woven through-air drying fabrics, that have a surface with a three-dimensional topography that facilitates shaping and structuring of a nascent tissue web during manufacturing. Molding and structuring of the web during manufacturing can impart three-dimensionality to the resulting tissue sheet or ply. In some cases, the three-dimensionality imparted to the resulting sheet or ply affects the physical properties of the final tissue product, such as sheet bulk, stretchability, and stretch energy absorption. For example, the finished product can include a plurality of ridges that are substantially oriented in the machine direction (MD) that can be pulled out when the product is subjected to strain in the cross direction (CD), resulting in increased CD stretch and stretch energy absorption.

[0066] Three-dimensional fabrics suitable for the purposes of the present invention are those having an upper surface (also referred to as a web contacting surface) and a lower surface, wherein the upper surface comprises a three-dimensional topography. During wet molding or through-air drying, the wet tissue paper web contacts the top surface and is stretched into a three-dimensional topographical form corresponding to the three-dimensional topography of the top surface.

[0067] In some cases, the three-dimensional fabric may have a textured web contacting surface comprising substantially continuous longitudinal ridges separated by valleys, such as those disclosed in U.S. Pat. No. 6,998,024, the contents of which are incorporated herein in a manner consistent with the present disclosure. In certain preferred cases, the fabric used to make the tissue paper product of the present invention may have a textured web contacting surface comprising substantially continuous longitudinal ridges separated by valleys, the ridges being formed by a plurality of warp strands combined together, wherein the ridge height is 0.5 to about 3.5 mm, the ridge width is about 0.3 cm or greater, and the frequency of the ridges in the cross-machine direction of the fabric is about 0.2 to about 3 per cm.

[0068] In other cases, the three-dimensional fabric may have a textured web contact surface comprising substantially continuous longitudinal ridges separated by valleys, such as those disclosed in U.S. Pat. No. 7,611,607, the contents of which are incorporated herein in a manner consistent with the present disclosure. Such a fabric may have a web contact surface comprising substantially continuous longitudinal ridges separated by valleys, the ridges being formed by a plurality of warp strands grouped together and supported by a plurality of weft strands of two or more diameters; wherein the ridges have a width of about 1 mm to about 5 mm, more specifically about 1.3 mm to 3.0 mm, more specifically about 1.9 to 2.4 mm; and the ridges have a frequency of about 0.5 to 8 per centimeter, more specifically about 3.2 to 7.9 per centimeter, and still more specifically about 4.2 to 5.3 per centimeter in the transverse direction of the fabric.

[0069] In other cases, the three-dimensional fabric may have a textured sheet contact surface that is waffle-shaped in structure, such as those disclosed in U.S. Patent 7,300,543, the contents of which are incorporated herein in a manner consistent with the present disclosure. For example, the three-dimensional fabric may have a deep, discontinuous pit structure having a series of regular, distinct, relatively large depressions surrounded by raised warp strands or raised weft strands. The pits may be of any shape, with relatively flat or uneven upper edges on the sides of the pits, but the lowest points of the individual pits are not connected to the lowest points of the other pits. The most common examples are all waffle-shaped structures, and may be warp-based, weft-based, or coplanar. The pit depth may be from about 250% to about 525% of the diameter of the warp strands.

[0070] In other cases, the three-dimensional fabric may have a textured sheet contact surface formed by a nonwoven material bonded to a woven support structure. For example, the three-dimensional fabric may include a protruding frame, which is connected to a reinforcing structure and extends outward from the reinforcing structure to define a deflection channel between the protrusions, such as disclosed in U.S. Patent No. 5,628,876, the content of which is incorporated herein in a manner consistent with the present disclosure. The protruding frame includes a continuous or semi-continuous pattern, and may have a height of about 0.10 to about 3.00 mm, such as about 0.50 to about 1.00 mm. Alternatively, the fabric may include a plurality of parallel, spaced and substantially rectangular polymer protrusions, such as those disclosed in U.S. Patent No. 9,512,572, the content of which is incorporated herein in a manner consistent with the present disclosure. In this case, the protrusions may have similar sizes, and have substantially straight, parallel sidewalls of substantially equal height and width, and the height and width may be in the range of about 0.5 mm to about 1.00 mm.

[0071] In a particularly preferred embodiment, the tissue paper product of the present invention is produced using a non-compressive drying method that tends to maintain or increase the thickness of the wet web, including but not limited to through-air drying, infrared radiation, microwave drying, and the like. Due to its commercial availability and practicality, through-air drying is well known and is the preferred mode of non-compressive drying of webs for the purposes of the present invention. The through-air drying process and apparatus can be conventional processes and apparatus known in the papermaking industry. In some cases, it is preferred to use a through-air drying fabric having a web contacting surface with the above-mentioned three-dimensional topography. As is well known in the art, after manufacture, the web can subsequently be converted by methods such as calendering, embossing, printing, lotion treatment, cutting, folding, and packaging. Particularly preferred is a method in which a plurality of embossments are applied to at least one surface of the tissue paper web, as will be discussed in more detail below.

[0072] In one embodiment of the present invention, the tissue paper product has a plurality of embossings. In one embodiment, the embossing pattern is applied only to the first ply, so each ply in the two plies is used for different purposes and is visually distinguishable. For example, the embossing pattern on the first ply particularly provides improved aesthetics about thickness and quilted appearance, while the unembossed second ply is designed to enhance functional qualities, such as absorbency, thickness and strength. In another embodiment, the fibrous structure product is a two-ply product, wherein both plies contain a plurality of embossings. Suitable embossing methods include, for example, those disclosed in U.S. Patents 5,096,527, 5,667,619, 6,032,712 and 6,755,928.

[0073] In a particularly preferred embodiment, the multi-ply embossed tissue paper product according to the present invention may be used Figure 1A To produce the embossed tissue product 60, the first tissue ply 20 is conveyed through a series of idler rolls 22 toward a nip 24 between an engraved roll 26 and an embossing roll 28. The engraved roll 26 rotates in a counterclockwise direction, while the embossing roll 28 rotates in a clockwise direction. The first tissue ply 20 forms the top ply in the final embossed multi-ply tissue product 60.

[0074] The engraved roller 26 is typically a hard, non-deformable roller, such as a steel roller. The embossing roller 28 can be a substantially smooth roller, more preferably a smooth roller with a cover layer, or made of a natural or synthetic rubber, such as polybutadiene or a copolymer of ethylene and propylene, etc. In a preferred embodiment, the embossing roller 28 has a hardness greater than about 40 Shore (A), such as from about 40 Shore (A) to about 100 Shore (A), and more preferably from about 40 Shore (A) to about 80 Shore (A). By providing a receiving roller with such a hardness, the design of the engraved roller does not press as deeply into the embossing roller as in conventional equipment.

[0075] The embossing roll 28 and the engraved roll 26 are pressed together to form a nip 24 through which the web 20 passes to impart an embossing pattern to the web. The engraved roll 26 includes a plurality of protrusions 30, also referred to as embossing elements, extending radially therefrom. The protrusions are arranged to form a first embossing pattern. The height of the protrusions 30 may be greater than about 1.30 mm, such as about 1.30 to about 1.50 mm, and more preferably about 1.35 to about 1.45 mm. Typically, the engraved roll will include more than about 1.50 mm of protrusions 30. Figure 1A The protrusions shown are many more protrusions. In addition, the engraved roll may include additional protrusions forming a second embossing pattern or a third embossing pattern.

[0076] Continue to refer Figure 1A, force or pressure is applied to one or both of the rollers 26, 28 so that the rollers 26, 28 are urged toward each other to form the nip 24 therebetween. The pressure will deform the embossing roller 28 around the protrusion 30 so that when the web 20 is pressed around the protrusion 30 onto the rest area 31 (i.e., the outer surface area of ​​the roller around the protrusion), an embossing 65 (e.g., Figure 1B shown).

[0077] To form a two-ply tissue product, the second tissue ply 40 is conveyed around an idler roll 42 and then enters a nip 44 between a substantially smooth roll 46, which may be made of rubber, and an intermeshing roll 48, which may be a steel roll. The second tissue ply 40 is adapted to form the bottom ply in a final multi-ply tissue product 60. As it is conveyed, the second tissue ply 40 passes through a second nip 50 formed between the engraved roll 26 and the intermeshing roll 48, where it contacts the first tissue ply 20, which now bears the embossments 65 as a result of being impressed by the engraved roll 26. The first ply 20 and the second ply 40 are joined together as they pass through the nip 50 to form the multi-ply tissue product 60.

[0078] Continue to refer to Figure 1A In certain embodiments, after the first tissue ply 20 passes through the nip 24 between the engraved roller 26 and the embossing roller 28, the gluing unit 52 applies glue to the embossings 65 (at Figure 1B 4, the embossed first ply 20 is formed on the outer surface of the embossed first tissue ply 20 by embossing by the first protrusions 30. The embossed first tissue ply 20 with the applied glue then advances further to the nip 50 between the engraved roll 26 and the intermeshing roll 48. At this point, the unembossed second ply 40 is attached to the embossed first ply 20 and then conveyed around the intermeshing roll 48 to form a two-ply tissue product 60 which is subsequently wound into a roll (not shown).

[0079] like Figure 1B As shown, the resulting two-ply tissue product 60 includes a first ply 20 and a second ply 40, wherein the first ply 20, which forms the top ply of the tissue product 60, is provided with an embossment 65, but the second ply 40 is not heavily embossed and generally does not have a significant embossment. Thus, in this manner, the first tissue ply 20 is embossed, while the second ply 40 is not embossed. The degree of embossing of the first tissue ply 20 can be achieved in several ways. For example, the embossing roller 28 can be made of materials having different softnesses to allow the first protrusions 30 and the second protrusions 32 to have a higher penetration depth. Alternatively, the pressure at the nip 24 between the engraved roller 26 and the embossing roller 28 can be varied.

[0080] Further references Figure 1B, the product 60 has an upper surface 62 and an opposite lower surface 63, wherein an embossment 65 is generally formed along the upper surface 62. The embossment 65 is generally in the form of a depression below the surface plane 45 of the upper surface 62. The embossment 65 may have a depth 47, which is generally measured between the upper surface 45 of the product 60 and the bottom surface 43 of the embossment 65.

[0081] The tissue webs prepared as described herein can be incorporated into multi-ply tissue products, such as products comprising two, three or four plies. The individual plies can be joined together using known techniques, such as using a laminating adhesive to hold the plies together. In particularly preferred cases, the plies can be combined using an embossing-laminating assembly that uses mechanical and adhesive means to join the plies. For example, the plies can be embossed and joined together using at least one steel embossing roller, at least one rubber-coated embossing counter-roller and at least one roller for dispensing adhesive, which can be applied to the tissue web after the tissue web leaves the pair of embossing rollers.

[0082] After twisting, the tissue product can be further converted by slitting, perforating, cutting and / or winding. For example, the tissue product can be in the form of a roll, wherein the sheets of the embossed tissue product are spirally wound around themselves with or without a core.

[0083] Typically, the tissue paper product of the present invention comprises cellulose fibers. Cellulosic fibers suitable for use in conjunction with the present invention include secondary (recycled) papermaking fibers and virgin papermaking fibers in any proportion. Such fibers include, but are not limited to, hardwood and softwood fibers and non-wood fibers. Non-cellulose synthetic fibers may also be included as part of the fiber furnish. In certain preferred cases, the tissue paper product of the present invention comprises cellulose pulp fibers, such as a blend of hardwood kraft pulp fibers and softwood kraft pulp fibers. However, cellulose pulp fibers derived from other wood and non-wood sources may be present in the tissue paper product of the present invention, such as cereal straw (wheat, rye, barley, oats, etc.), stalks (corn, cotton, sorghum, grass yucca (Hesperaloe funifera), etc.), sugar cane (bamboo, bagasse, etc.) and grass (Spanish grass, lemon, Indian grass (sabai), switchgrass, etc.).

[0084] The tissue paper webs prepared according to the present invention may be stratified or non-stratified (blended). The stratified sheets may have two, three or more layers. For tissue paper sheets that will be converted into a multi-layer sheet product, it is advantageous to form the product from layers having at least two layers, such that when the layers are arranged facing each other, the outer layers contain primarily hardwood fibers and the inner layers contain primarily softwood fibers. The tissue paper sheets according to the present invention will be suitable for all forms of tissue paper products, including but not limited to toilet paper, kitchen towels, facial tissue and napkins for the consumer and service markets.

[0085] In one example, the present invention provides an embossed tissue product, which includes a through-air dried tissue product that may be creped or uncreped. In one example, the tissue product includes two or more tissue webs that have been wet-laid, through-air dried, and uncreped. After the tissue webs are manufactured, the two separate webs are laminated and embossed such that the resulting tissue product consists essentially of a first ply and a second ply, wherein the first ply forms a first upper surface of the tissue product and has a plurality of embossments disposed thereon.

[0086] The tissue paper product of the present invention is preferably embossed. In one embodiment, Figure 3 and 4 As shown, the tissue paper product 60 includes a plurality of embossments 65, which in the embodiment shown are discrete and non-linear. The embossment area may be about 15% or less, such as 12% or less, such as 10% or less, such as about 4% to about 10% or about 5% to about 8%.

[0087] Continue to refer to Figure 3 and 4 , the embossing pattern 90 includes a plurality of embossments 65 that are completely composed of nonlinear thread elements 80 and are substantially free of point embossments. In this case, the thread elements may constitute 100% of the embossed area. In other cases, at least about 90%, such as at least about 92%, such as at least about 94%, of the embossed area is composed of thread elements, and more preferably, is composed of nonlinear thread elements.

[0088] In addition to the plurality of embossments 65, the tissue product 60 has a first surface 62 that includes a plurality of substantially machine direction (MD) oriented ridges 66 that are spaced apart from one another and define valleys 67 therebetween. The plurality of substantially machine direction oriented ridges 66 are generally linear elements that form a background pattern 70 on which an embossed pattern 90 is applied. The substantially machine direction oriented ridges 66 are periodically interrupted by non-linear embossed elements 80 that comprise the embossed pattern 90. The substantially machine direction oriented ridges 66 may be spaced apart from one another such that the background pattern 70 includes 10 or more ridges per 10 cm, such as from 10 to about 60 ridges per 10 cm, such as from about 30 to about 50 ridges per 10 cm, as measured along a transverse axis.

[0089] Although Figure 3 and 4 The background pattern 70 shown in FIG. 7 is composed of linear, substantially longitudinally oriented ridges 66, but the present invention is not limited thereto. In other cases, the background pattern can be composed of non-linear line elements. For example, the background pattern can be composed of zigzag or curved line elements. In a particularly preferred case, the background pattern includes a plurality of elements, whether linear or non-linear, which are arranged parallel to each other so that the elements do not intersect each other.

[0090] The embossed pattern 90 generally overlies the background pattern 70 of the MD-aligned ridges 66 and has a primary orientation axis 92 oriented at an angle (α) relative to the MD axis 100. In some cases, the embossed pattern may be disposed at an angle (angle α) relative to the MD axis, such as from about 10 to about 40 degrees, such as from about 15 to about 35 degrees.

[0091] In a particularly preferred embodiment, for example Figure 3 and 4 As shown, the embossing 65 can be in the form of discrete nonlinear elements 80 that form a recognizable shape, such as a V-shape. The nonlinear elements 80 can be arranged in a motif 94 that can be further arranged to form a pattern 90, such as the mountain-shaped pattern shown. Although in certain embodiments, the embossing can form a recognizable shape, such as a letter or a geometric shape, such as a triangle, rhombus, trapezoid, parallelogram, diamond, star, pentagon, hexagon, octagon, etc., the present invention is not limited thereto. In other embodiments, the embossing can include nonlinear elements that are arranged but not formed into a recognizable geometric shape.

[0092] Just as the shapes of the embossments may vary, their sizes may also vary. In some cases, the embossments may include a plurality of nonlinear elements having a length (L) of about 20.0 mm or greater, such as about 25.0 mm or greater, such as about 30.0 mm or greater, such as about 20.0 to about 60.0 mm. The width of the nonlinear embossed elements may be less than about 2.0 mm, such as less than about 1.5 mm, such as less than about 1.0 mm, such as about 0.20 to about 2.0 mm, such as about 0.50 to about 1.50 mm. The width of the nonlinear embossed elements may be uniform along their length, or may vary. In those cases where the width varies, it is preferred that the width varies by less than about 1.0 mm. For example, the elements may have a first width of about 0.5 to about 0.75 mm and a second width of about 1.0 to about 1.5 mm.

[0093] The embossed elements may have any suitable height known to those skilled in the art. For example, the embossed elements may exhibit a height of greater than about 0.10 mm and / or greater than about 0.20 mm and / or greater than about 0.30 mm to about 3.60 mm and / or to about 2.75 mm and / or to about 1.50 mm. Typically, the embossing height is measured from the uppermost surface plane of the tissue paper product and the embossing bottom plane using a Keyence microscope and imaging software as described herein. Exemplary measurements of embossing height are shown in the accompanying drawings. Figures 5A-5C .

[0094] Compared to prior art commercial two-ply embossed tissue products, tissue products made according to the present invention have a relatively high basis weight, such as greater than about 45 gsm, more preferably greater than about 47 gsm and more preferably greater than about 50 gsm, for example from about 45 to about 65 gsm, for example from about 50 to about 60 gsm and more preferably from about 50 to about 55 gsm. Table 1 below compares the flexural rigidity of the tissue products of the present invention with the flexural rigidity of prior art multi-ply embossed tissue products.

[0095] Table 1

[0096]

[0097] Therefore, in certain embodiments, the present invention provides a multi-ply embossed tissue product having a basis weight of greater than about 45 gsm, such as from about 45 to about 65 gsm, such as from about 50 to about 60 gsm, more preferably from about 50 to about 55 gsm, and a GM flexural rigidity of less than about 600 mg / cm, more preferably less than about 575 mg / cm, even more preferably less than about 560 mg / cm, such as from about 450 to about 600 mg / cm, even more preferably from about 500 to about 560 mg / cm. Therefore, the multi-ply embossed tissue product of the present invention has sufficient basis weight to have a good hand feel, but has a relatively low stiffness so as to have a good hand feel and is not overly rigid.

[0098] In other embodiments, the present invention provides a multi-ply embossed tissue product having a relatively low CD flexural rigidity, especially in relation to MD flexural rigidity. Thus, in certain embodiments, the tissue product of the present invention has particularly good drape and good hand feel in the cross direction. For example, the tissue product of the present invention can be embossed and comprise two or more plies and can have a CD flexural rigidity of less than about 400 mg*cm, more preferably less than about 380 mg*cm, and even more preferably less than about 375 mg*cm, such as from about 300 to about 400 mg*cm, and more preferably from about 350 to about 375 mg*cm. The above-mentioned tissue product can have an MD flexural rigidity greater than the CD flexural rigidity, such that the ratio of MD flexural rigidity to CD flexural rigidity is greater than about 1.0. In particularly preferred cases, the ratio of MD flexural rigidity to CD flexural rigidity of tissue paper products prepared according to the present invention is greater than about 1.5, more preferably greater than about 2.0, such as from about 1.0 to about 3.0, more preferably from about 1.5 to about 2.5, such as from about 2.0 to about 2.5.

[0099] The tissue product of the present invention may also have improved wet performance, especially wet resilience. Usually, wet resilience is characterized as wet elastic strain ratio in this article, and is the measure of the elastic strain of the applied strain when the tissue product is compressed under a specified load. The scope of the wet elastic strain ratio will be between zero for the wet elastic strain ratio of a completely elastic solid without plastic deformation to the wet elastic strain ratio of a completely plastic solid without elastic recovery. Ideally, the tissue product, particularly the tissue product, will be very elastic when wet, so that when the product is wetted in use and then wrung out, it will rebound to its initial thickness. By rebounding to its initial thickness, the product maintains its void volume, and can be used to absorb another overflow. Therefore, in certain embodiments, the tissue product of the present invention has greater than about 32%, more preferably greater than about 34%, still more preferably greater than about 36%, for example, about 32% to about 40%, for example, about 34% to about 40% wet elastic strain ratio. The wet elastic strain ratios of various prior art tissue products and tissue products of the present invention are provided in Table 2 below.

[0100] Table 2

[0101]

[0102] In addition to having improved stiffness and wet resilience, the tissue paper products of the present invention may also have improved absorbent properties. For example, the tissue paper products of the present invention are able to absorb a greater percentage of liquid spills and better retain the absorbed spills than prior art tissue paper products. Thus, in certain embodiments, the present invention provides a multi-ply embossed tissue paper product having a residual water (W) of less than about 0.15 g, such as less than about 0.12 g, such as less than about 0.10 g, such as from about 0.05 to about 0.15 g, more preferably from about 0.05 to about 0.10 g. 残留 In a particularly preferred embodiment, the present invention provides a two-ply through-air dried embossed tissue product having a basis weight of from about 50 gsm to about 55 gsm, a GMT of from about 2,000 g / 3" to about 4,000 g / 3", and a residual moisture value of from about 0.05 g to about 0.15 g, more preferably from about 0.05 g to about 0.10 g.

[0103] The tissue paper products of the present invention not only absorb more liquid spills initially, but also retain more spills over time compared to other prior art tissue paper products. For example, in one embodiment, the present invention provides a multi-ply embossed tissue paper product having a drip time (DT) of greater than about 20 seconds, such as greater than about 30 seconds, such as greater than about 45 seconds. In certain preferred embodiments, the tissue paper product is substantially non-drip; that is, the tissue paper product does not drip any fluid in the drip test described in the Test Methods section below. In a particularly preferred embodiment, the present invention provides a two-ply through-air dried embossed tissue paper product having a basis weight of about 50 gsm to about 55 gsm, a GMT of about 2,000 g / 3" to about 4,000 g / 3", and a drip time of greater than about 30 seconds, more preferably greater than about 45 seconds.

[0104] The absorbent properties of tissue paper products made according to the present invention as compared to the prior art are further detailed in Table 3 below.

[0105] Table 3

[0106]

[0107]

[0108] In other cases, tissue products prepared according to the present invention initially absorb more liquid spills and then retain more of the absorbed spills over time. For example, the amount of liquid spills absorbed and retained by a tissue product over a period of time is referred to herein as the liquid absorption and retention rate and is calculated as:

[0109]

[0110] It may be greater than about 94%, such as greater than about 95%, such as greater than about 96%, such as from about 95% to about 99%.

[0111] In other cases, the tissue paper products of the present invention retain a greater percentage of absorbed liquid overflow over time and therefore have an improved absorbed liquid retention, calculated as follows:

[0112]

[0113] Greater than about 98%, such as greater than about 99%, such as about 100%. Because the tissue paper products of the present invention retain a greater percentage of absorbed spills, the products typically have a relatively low discharge weight (W D ), for example less than about 0.10 g, for example less than about 0.08 g, for example less than about 0.05 g, for example from about 0.0 to about 0.10 g.

[0114] Each of the above-described absorbency improvements of the tissue paper products of the present invention are measured according to the Drip Test, as described in the Test Methods section below.

[0115] Test Method

[0116] The following test method is to be performed on samples that have been conditioned in a TAPPI conditioning chamber at a temperature of 73.4 ± 3.6 °F (approximately 23 ± 2 °C) and a relative humidity of 50 ± 5% for 4 hours prior to testing.

[0117] Stretch

[0118] Tensile testing was done according to TAPPI Test Method T-576 "Tensile properties of towel and tissue products (using constant extension)", wherein the test was conducted on a tensile testing machine maintained at a constant extension, with each sample tested having a width of 3 inches. More specifically, samples for dry tensile strength testing were prepared by cutting 3 ± 0.05 inch (76.2 mm ± 1.3 mm) wide strips in the machine direction (MD) or cross direction (CD) using a JDC precision sample cutter (Thwing-Albert Instrument Company, Philadelphia, PA, Model JDC 3-10, Serial No. 37333) or equivalent equipment. The instrument used to measure tensile strength was an MTS Systems Sintech 11S, Serial No. 6233. The data acquisition software was MTS Windows 3.10 version (MTS Systems Corp., Research Triangle Park, NC). Depending on the strength of the sample being tested, a dynamometer with a maximum value of 50 Newtons or 100 Newtons is selected so that most of the peak load values ​​fall between 10% and 90% of the full scale value of the dynamometer. The gauge length between the jaws is 4 ± 0.04 inches (101.6 ± 1mm) for facial tissue and paper towels, and 2 ± 0.02 inches (50.8 ± 0.5mm) for toilet paper. The chuck speed is 10 ± 0.4 inches / minute (254 ± 1mm / min), and the fracture sensitivity is set at 65%. The sample is placed in the jaws of the instrument, centered in both the vertical and horizontal directions. Then the test is started, and it ends once the sample breaks. Depending on the direction of the sample being tested, the peak load is recorded as the "MD tensile strength" or "CD tensile strength" of the sample. Ten representative samples are tested for each product or sheet and the arithmetic mean of all the individual test samples is recorded in grams of force per 3 inch sample as the appropriate MD tensile strength or CD tensile strength for the product or sheet. The geometric mean tensile (GMT) strength is calculated and expressed in grams of force per 3 inch sample width. The tensile energy absorption (TEA) and slope are also calculated by the tensile tester. TEA is expressed in gm·cm / 2 The slope is reported in grams (g) or kilograms (kg). Both TEA and slope are directionally constrained and thus measure the MD and CD directions independently. The geometric mean TEA and geometric mean slope are defined as the square root of the product of the representative MD value and the representative CD value for a given property.

[0119] Flexural rigidity

[0120] The test is conducted on a 1 inch by 6 inch (2.54 cm x 15.24 cm) strip of tissue product sample. The tissue product to be tested should be free of creases, bends, folds, perforations and defects. A cantilever bend tester such as described in ASTM Standard D 1388 (Model 5010, Instrument Marketing Services, Fairfield, NJ) is used and operated at a ramp angle of 41.5 + 0.5 degrees and a sample slide speed of 120 mm / minute.

[0121] For each tissue product, this test sequence was performed a total of eight (8) times in each direction (MD and CD) using a new test piece for each measurement. The top surface of the first four strips was tested as the tissue product was cut facing upward. The last four strips were inverted so that the top surface of the tissue product as cut faced downward when the strip was placed on the horizontal platform of the tester. The average overhang length was determined by averaging the sixteen (16) readings obtained on the tissue product.

[0122] Overhang length MD = sum of 8 MD readings

[0123] Overhang length CD = sum of 8 CD readings

[0124] Total overhang length = sum of all 16 readings

[0125] Bending length MD = overhang length MD

[0126] Bending length CD = overhang length CD

[0127] Total bending length = total overhang length

[0128] Flexural rigidity = 0.1629 x W x C 3

[0129] Where W is the basis weight of the tissue product in pounds per 3000 ft 2 ; C is the bending length in cm (MD or CD or total); and the constant 0.1629 is used to convert the basis weight from English to metric units. The result is expressed in mg*cm2 / cm.

[0130]

[0131] Trickle test

[0132] The tissue paper product samples to be tested were cut into 5" x 5" dimensions using a punch cutter to ensure a straight edge from the center of the sheet without touching any perforations. Any damaged or abnormal product, such as crumpled, flipped or crushed, was discarded. A total of five (5) samples to be tested were prepared.

[0133] Two upper dish balances are used with a minimum resolution of 0.01 g. The first upper dish balance is equipped with a Formica patch of at least 7 inches by 7 inches and is tared to offset the weight of the patch. The second upper dish balance is equipped with a device for hanging the sample by a fixture after the sample is wetted, as further described below. The device is arranged so that the sample is suspended above the second upper dish balance by a fixture of twelve (12) inches. In addition, the second upper dish balance is equipped with a plastic square 3.5 inches by 3.5 inches by 1 inch weighing boat. The balance is tared to offset the weight of the boat. The two balances are arranged directly adjacent to each other to eliminate interference when the sample is moved from the first balance to the fixture above the second balance. In all cases, the weight is recorded when the reading on the upper dish balance becomes constant.

[0134] To perform the test, 5 mL of distilled water was measured using a pipette and dispensed onto the center of the Formica patch, being careful to ensure that the dispensed water was circular and no larger than approximately 2 inches (approximately 5.0 cm) in diameter. The weight of the water on the Formica patch was recorded in grams to the nearest hundredth (W I ). The sample is arranged so that the embossed side of the sheet, or the side facing the consumer on the outside of the roller, will face downward when placed on the water. The center of the sample is placed directly on top of the water on the first upper dish balance. As soon as the sample and water come into contact with each other, a timer is started. After 15 seconds, the sample is carefully removed from the balance by peeling the upper right corner toward the tester. As soon as the sample rises from the first balance, a timer is started. The amount of fluid left on the Formica patch that was not absorbed by the sample is recorded to the nearest hundredth of a gram. This value is the residual water (W 残留 ), unit is grams.

[0135] Once the sample is lifted off the first balance, it is transferred to the second balance in the fixture without disturbing the sample. Use a No. 1 Boston fixture with a 1.25 inch fixture opening or the like, and secure by clamping the upper right corner of the sample from 0.25 to 0.5 inches in the fixture. In this way, the sample is suspended above the weigh boat on the second tared upper pan balance. The test is completed 60 seconds from the time the sample is sheared onto the second balance.

[0136] When the sample first drips water onto the tared weigh boat on the second upper balance, record the time. This is the drip time (DT) in seconds. If the sample does not drip during the 60 second test period, its DT is recorded as >60s. After one minute, record the weight of the fluid collected in the weigh boat on the second balance to the nearest hundredth of a gram. This mass is referred to as the drain weight (W D ), unit is grams.

[0137] Based on the aforementioned test method, the following values ​​are reported:

[0138] (1) Residual water (W 残留 ), in grams (g), which is the mass of water on the first upper plate balance that is not absorbed by the sample;

[0139] (2) the drip time (DT), in seconds (s), which is the time on the timer when the sample first drips onto the tared boat; and

[0140] (3) Retained water (W 保留 ), in grams (g), is the amount of water retained by the sample at the end of the test method, calculated as follows:

[0141] Retained water (W 保留 )(g)=(W I (g)–W 残留 (g))–W D (g).

[0142] The above values ​​are the average of 5 replicates for each tissue product sample.

[0143] Wet resilience

[0144] Thickness versus load data were obtained using a Thwing-Albert Model EJA materials tester equipped with a 50N capacity load cell programmed to 45N to prevent overloading. The instrument was run under the control of the Thwing-Albert Motion Analysis Presentation Software (MAP). The instrument settings were as follows:

[0145]

[0146]

[0147] Cut a single conditioned sample piece to approximately two inches in diameter. Care should be taken to avoid damage to the center portion of the sample to be tested. Scissors or other cutting tools may be used. Test under the same temperature and humidity conditions used for conditioning the sample.

[0148] For the test, the sample is centered on the compression table below the compression base. Immediately before the test, the sample is saturated with 4.0g water / g fiber. The compression-relaxation procedure is repeated 3 times on the same sample. Compression and relaxation data are obtained using a clamping head speed of 0.1 inches / minute. The deflection of the load cell is obtained by testing in the absence of the sample. This is generally referred to as steel-to-steel data. Steel-to-steel data is obtained at a clamping head speed of 0.005 inches / minute. For the compression and relaxation part of the test, the clamping head position and the load cell data are recorded between the load cell range of 5 grams and 300 grams. Since the foot area is one square inch, this corresponds to a range of 5 grams / square inch to 300 grams / square inch. The maximum pressure applied to the sample is 300 grams / square inch. At 300 grams / square inch, the clamping head reverses its direction of travel. The clamping head position value is collected at a selected load value during the test. These correspond to pressure values ​​of 5, 10, 25, 50, 75, 100, 125, 150, 200, 300, 200, 150, 125, 100, 75, 50, 25, 10, 5 grams per square inch in both the compression and relaxation directions.

[0149] During the compression portion of the test, the gripper position values ​​were collected by the MAP software by defining 10 traps (Trap 1 to Trap 10) at load settings of C5, C10, C25, C50, C75, C100, C125, C150, C200, C300. During the return portion of the test, the gripper position values ​​were collected by the MAP software by defining ten return traps (Return Trap 1 to Return Trap 10) at load settings of R300, R200, R150, R125, R100, R75, R50, R25, R10, R5. The cycle of compression to 300 g / in2 and return to 5 g / in2 was repeated 3 times on the same sample without removing the sample. For a given product, the 3-cycle compression-relaxation test was repeated 5 times using a fresh sample each time. The results are reported as the average of 5 replicates. The values ​​for steel-steel and sample were obtained again. The steel-to-steel ratio is obtained for each batch tested. If multiple days are involved in the test, the values ​​are checked every day. The steel-steel value and the sample value are the average of four replicates (300 g).

[0150] The thickness value with units of millimeters (mm) was obtained by subtracting the average steel-steel grip catch value from the sample grip catch value for each entrapment point.

[0151] Microscopic examination

[0152] Tissue paper products produced according to the present invention can be analyzed by microscopy as described herein. In particular, three-dimensional surface topography and embossing can be analyzed by generating and analyzing product 3-D surface maps and cross-sections, such as Figure 5A and 5B Those shown in . Images were taken using a VHX-5000 digital microscope manufactured by Keyence Corporation of Osaka, Japan. The microscope was equipped with VHX-5000 communication software Ver 1.5.1.1. The lens was an ultra-compact, high-performance zoom lens VH-Z20R / Z20T.

[0153] The tissue product sample to be analyzed should be undamaged, flat, and include representative embossing. A tissue product sample approximately 4 inches by 4 inches in size works well.

[0154] A 3D image of the sample is obtained as follows:

[0155] 1. Turn on the digital microscope and follow the standard procedure for initializing the XY stage [Auto]

[0156] 2. Change the microscope magnification to x100.

[0157] 3. Place the tissue product sample on the table with the first embossment facing up toward the lens.

[0158] 4. If the tissue product does not lie flat, place weights along the perimeter as needed to keep the tissue lying flat on the table surface.

[0159] 5. Use the focus adjustment to bring the tissue paper into sharp focus.

[0160] 6. Select "Stitching" in the main menu. Select "3D stitching".

[0161] 7. Set the stitching method by selecting "Stitch around the current position".

[0162] 8. Select Z Settings to set the upper and lower composition ranges. The upper limit should be set by becoming above the highest focus that is sharp. The lower limit should be set by becoming below the lowest focus that is sharp. After setting the upper and lower ranges, click OK.

[0163] 9. Select “Start stitching” to start the image acquisition.

[0164] 10. Select "complete" and then "Confirm stitching results" when the desired area has been imaged.

[0165] 11. In the 3D menu, select "Height / Color view" to identify the embossing to be measured.

[0166] 12. In the 3D menu, select "Profile".

[0167] 13. With the "Profile line" tab selected to obtain a cross section of the tissue sample identified in step 11, select "Line" and use the cursor to draw a line on the identified portion of the sample. The line should bisect at least two adjacent embossments. The peaks to the right and left of the first embossment should be relatively flat (less than 10% height difference).

[0168] 14. Use the "Pt-Pt" vertical measurement tool to measure the peak height of the embossing. If the height difference between the peaks is greater than 10%, select another first embossing to measure. The height of the embossing can then be measured using the VHX-5000 Communication Software Ver 1.5.1.1.

[0169] The surface area of ​​the tissue product covered with embossing was measured using the Keyence microscope and image analysis software described above. An image of the tissue was acquired at 20X magnification and the images were stitched as described above to include at least one embossing pattern in the field of view. A 3-D height / color image was created and saved.

[0170] Open the saved 3-D height / color image in "2-D Rendering" mode and measure the embossed area by first selecting "Measure" from the on-screen menu, followed by "Auto" area measurement, then selecting the "Color" option and measuring by clicking inside the colored area of ​​the embossed image.

[0171] Once the measurement is taken, use the "Fill" and "Eliminate Small Grains" features to fill the embossing, which is typically the lowest point in the height map image and below the surface plane of the tissue product, and then select the forming step. If there are embossed areas that need to be filled or edited to produce an accurate 2-D highlight of the embossing, produce an accurate area representation by selecting "Edit", "Fill". Select "Next" for result display, tabulate the results, select "MeasureResult", and display the calculated area ratio percentage. Repeat the measurement for 3 different areas of the tissue product sample and report the arithmetic average area ratio percentage measured as the embossed area.

[0172] Example

[0173] The basesheet was made using a through-air drying papermaking process, which is generally referred to as "uncreped through-air drying" ("UCTAD") and is generally described in U.S. Pat. No. 5,607,551, the contents of which are incorporated herein in a manner consistent with the present disclosure. A basesheet having a target water-free dry basis weight of about 27 grams per square meter (gsm) and a GMT of about 1,800 g / 3" was produced. The basesheet was then converted and spirally wound into a roll-type tissue product product as described in this example.

[0174] In all cases, the basesheet was made from a furnish comprising northern softwood kraft (NSWK) and eucalyptus hardwood kraft (EHWK) using a layered headbox which was caused by three stock pumps to form a web having three layers (two outer layers and one middle layer). The two outer layers comprised EHWK (each comprising 20% ​​by weight of the tissue paper web), and the middle layer comprised NSWK (the middle layer comprising 60% by weight of the tissue paper web). Strength was controlled by adding carboxymethyl cellulose (CMC) and permanent wet strength resins, and / or by refining the furnish.

[0175] The tissue paper web was formed on a Voith Fabrics TissueForm V forming fabric, vacuum dewatered to a consistency of about 25%, and then subjected to a rush transfer rate of 24% when transferred to the transfer fabric. The transfer fabric was Voith T807-5 (commercially available from Voith Paper, Inc., Appleton WI). The web was then transferred to a woven through-air drying fabric having a plurality of substantially machine direction (MD) oriented ridges spaced about 3.5 mm from each other. The MD ridges were substantially continuous in the MD direction of the fabric and were woven in a parallel, spaced arrangement to define valleys therebetween, wherein the depth of the valleys was about 1.5 mm. The transfer to the through-air drying fabric was performed using a vacuum level of greater than 6 inches of mercury during the transfer. The web was then dried to about 98% solids before winding.

[0176] The basesheet prepared as described above was converted into a two-ply sheet-to-roll tissue product. Specifically, the basesheet was calendered using a patterned steel roll and a 40 P&J polyurethane roll at a load of 30 pli substantially as described in U.S. Patent No. 10,040,265, the contents of which are incorporated herein in a manner consistent with the present invention.

[0177] Then basically Figure 1A The embossing and lamination shown convert the calendered base sheet into a two-ply product. Various engraved rolls were evaluated to assess their effect on the properties of the resulting tissue paper product. The performance of the engraved rolls is summarized in Table 4 below. In the case where the embossing pattern includes elements with more than one thread element, the length of the longest thread element is reported as the maximum thread element length.

[0178] Table 4

[0179]

[0180] The two-ply tissue product was then converted into a rolled towel product and physically tested, the results of which are shown in Tables 5 and 6 below.

[0181] Table 5

[0182]

[0183] Table 6

[0184]

[0185] Implementation

[0186] In a first embodiment, the present invention provides an embossed multi-ply tissue product comprising a first outer surface, an opposing second outer surface, and a plurality of embossments disposed on at least the first outer surface, the product having a drip time (DT) greater than about 30 seconds.

[0187] In a second embodiment, the present invention provides residual water (W 残留 ) value is from about 0.05 to about 0.15g of the tissue paper product of the first embodiment.

[0188] In a third embodiment, the present invention provides a tissue paper product of the first embodiment or the second embodiment having a liquid absorption and retention rate of greater than about 94%.

[0189] In a fourth embodiment, the present invention provides a tissue paper product according to any one of the first to third embodiments having a fluid discharge weight (W) of less than about 0.10 g. D ).

[0190] In a fifth embodiment, the present invention provides a tissue product of any of the first through fourth embodiments having a basis weight of from about 40 to about 60 grams per square meter (gsm) and a geometric mean tensile strength (GMT) of from about 2,000 to about 4,000 g / 3".

[0191] In a sixth embodiment, the present invention provides the tissue product of any one of the first through fifth embodiments, wherein the plurality of embossments are discrete line elements and the embossed area is less than about 10%.

[0192] In a seventh embodiment, the present invention provides a tissue paper product of any one of the first to sixth embodiments, wherein the tissue paper product comprises a first tissue paper layer and a second tissue paper layer, wherein the first tissue paper layer has a first upper surface and the plurality of embossments disposed thereon are discrete line elements and the embossment area is less than about 10%.

[0193] In an eighth embodiment, the present invention provides the tissue paper product of any one of the first through seventh embodiments, wherein the embossments disposed thereon are discrete line elements and are non-linear.

[0194] In a ninth embodiment, the present invention provides a tissue paper product of any one of the first to eighth embodiments, further comprising a background pattern disposed on at least the first outer surface. In certain embodiments, the background pattern comprises a plurality of spaced-apart parallel line elements having a width of from about 2.0 mm to about 6.0 mm.

[0195] In a tenth embodiment, the present invention provides the tissue product of any one of the first through ninth embodiments having a wet elastic strain ratio greater than about 32%.

[0196] In an eleventh embodiment, the present invention provides the tissue paper product of any one of the first through tenth embodiments having a GM flexural rigidity of less than about 600 mg*cm.

[0197] In a twelfth embodiment, the present invention provides the tissue product of any one of the first through eleventh embodiments having a ratio of CD flexural rigidity to MD flexural rigidity greater than one.

Claims

1. An embossed multi-ply tissue paper product comprising a first through-air dried ply and a second through-air dried ply, wherein each of the first through-air dried ply and the second through-air dried ply comprises a permanent wet strength resin, and wherein the first through-air dried ply has a first outer surface, an opposing second outer surface, a plurality of embossments disposed on at least the first outer surface, and a background pattern disposed on at least the first outer surface, wherein the background pattern is unembossed and has an embossed area of ​​less than 15%, wherein the embossed pattern comprises discrete non-linear elements, and the background pattern comprises a plurality of parallel linear elements that are periodically interrupted by the embossed pattern, and wherein the product has a drip time of greater than 30 seconds.

2. The embossed multi-ply tissue paper product according to claim 1, having a residual moisture value of 0.05 g to 0.15 g.

3. The embossed multi-ply tissue paper product of claim 1 having a liquid absorption and retention rate greater than 94%.

4. The embossed multi-ply tissue product of claim 1 having a fluid discharge weight of less than 0.10 g.

5. The embossed multi-ply tissue paper product of claim 1 wherein said product is comprised of a first through-air dried ply and a second through-air dried ply.

6. The embossed multi-ply tissue product of claim 5 wherein said first through-air dried ply and said second through-air dried ply are uncreped.

7. The embossed multi-ply tissue product of claim 1 having a basis weight of 40 to 60 grams per square meter and a geometric mean tensile strength of 2,000 to 4,000 g / 3".

8. The embossed multi-ply tissue product of claim 1, consisting of a first tissue ply and a second tissue ply and having a basis weight of 50 to 55 grams per square meter and a geometric mean tensile strength of 3,000 to 4,000 g / 3".

9. The embossed multi-ply tissue product of claim 1 wherein the plurality of embossments are discrete line elements and the embossed area is less than 10%.

10. The embossed multi-ply tissue product of claim 9, wherein the plurality of discrete line elements embossing is non-linear.

11. The embossed multi-ply tissue product of claim 1 further comprising a background pattern disposed on at least the first outer surface.

12. The embossed multi-ply tissue product of claim 11, wherein the background pattern comprises a plurality of spaced-apart parallel line elements, the line elements having a width of 2.0 mm to 6.0 mm.

13. The embossed multi-ply tissue product of claim 1 having a sheet bulk of 15 cc / g to 20 cc / g.

14. The embossed multi-ply tissue product of claim 1 having a geometric mean tensile strength greater than 3,000 g / 3" and a stiffness index of 3.0 to 6.

0.

15. A non-drip tissue paper product comprising a first tissue paper ply and a second tissue paper ply, wherein the first tissue paper ply and the second tissue paper ply each comprise a permanent wet strength resin, the first tissue paper ply having a first upper surface, a plurality of embossments disposed on the first upper surface, and a background pattern disposed at least on the first upper surface, wherein the background pattern is unembossed and has an embossed area of ​​less than 15%, wherein the embossed pattern comprises discrete non-linear elements and the background pattern comprises a plurality of parallel linear elements that are periodically interrupted by the embossed pattern, the tissue paper product having a fluid discharge weight of less than 0.15 g.

16. The no-drip tissue product of claim 15 having a fluid discharge weight of zero.

17. The no-drip tissue product of claim 15 wherein said first tissue ply and said second tissue ply are through-air dried and said product has a basis weight of 50 to 60 grams per square meter and a geometric mean tensile strength of 3,000 to 4,000 g / 3".

18. The no-drip tissue paper product of claim 15 having a residual moisture value of less than 0.15 g.

19. The no-drip tissue paper product of claim 15 having a liquid absorption and retention rate of 94% to 99%.

20. An embossed multi-ply tissue product having a first outer surface and an opposing second outer surface, the product comprising a first through-air dried tissue ply and a second through-air dried tissue ply, the first through-air dried tissue ply and the second through-air dried tissue ply each comprising a permanent wet strength resin, the first through-air dried tissue ply having a first surface, the first surface forming a first outer surface of the product and comprising a background pattern and a first embossing pattern, the first embossing pattern comprising discrete non-linear linear elements, wherein the background pattern is unembossed, and wherein the first embossing pattern covers 5.0% to 10.0% of the first outer surface of the tissue product, wherein the background pattern comprises a plurality of parallel linear elements that are periodically interrupted by the first embossing pattern, the product having a basis weight of 50 g / m2 to 60 g / m2, a geometric mean tensile strength of 3,000 g / 3" to 4,000 g / 3", and a drip time greater than 30 seconds.

21. The embossed multi-ply tissue product of claim 20 having a drip time greater than 45 seconds.

22. The embossed multi-ply tissue paper product of claim 20 having a residual moisture value of less than 0.15 g.

23. The embossed multi-ply tissue paper product of claim 20 having a liquid absorption and retention greater than 94%.

24. The embossed multi-ply tissue product of claim 20 having a fluid discharge weight of less than 0.15 g.

25. The embossed multi-ply tissue product of claim 20 having a sheet bulk of 15 cc / g to 20 cc / g.

26. The embossed multi-ply tissue product of claim 20 having a Stiffness Index of 3.0 to 6.

0.

27. The embossed multi-ply tissue product of claim 20, wherein the elements of the discrete non-linear linear elements have a length of 20.0 mm to 60.0 mm and a depth of 500 μm to 800 μm.

28. The embossed multi-ply tissue product of claim 20, wherein at least 90% of the embossed area consists of thread element embossing.

29. The embossed multi-ply tissue product of claim 20, wherein said first embossment pattern is free of point embossing.

30. The embossed multi-ply tissue product of claim 20, wherein at least 50% of the discrete non-linear linear elements have a length greater than 20.0 mm.

31. The embossed multi-ply tissue product of claim 20, wherein the embossed area comprises 0.0% to 1.0% point embossments and 5.0% to 10.0% discrete non-linear line elements.

Images