Absorbent paper product having unique physical strength properties

Abstract

To provide an absorbent towel paper product having vertical lines and horizontal lines perpendicular to the vertical lines.SOLUTION: The absorbent towel paper product comprises two plies of absorbent towel paper web, wherein each paper web comprises from about 20% to about 90% by weight on a dry fiber basis of the towel paper web of a refined long fiber softwood pulp fiber mixture comprising from about 18.5% to about 88.5% by weight on a dry fiber basis of the towel paper web of long fiber softwood pulp fibers, wherein the long fiber softwood pulp fibers are optionally refined prior to being added to the mixture; from about 0.25% to about 5.0% by weight on a dry fiber basis of the tissue paper web of a cationic strength polymer; From about 10% to about 55% of a hardwood pulp fiber mixture, by weight of the dry fiber basis of the tissue paper web; SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 62 / 396,812, filed September 19, 2016.

[0002] Field of Disclosure This disclosure relates to two-ply paper products. More particularly, this disclosure relates to two-ply absorbent paper products with unique physical strength properties. Even more particularly, this disclosure relates to two-ply absorbent paper products with high dry tensile strength and a high ratio of cross-grain wet tensile strength to cross-grain dry tensile strength. [Background technology]

[0003] Tissue products, such as facial tissue, paper towels, bath tissue, napkins, and other similar products, are designed to include several important properties. For example, the products should have good bulk, good absorbency, a soft feel, and good strength and durability. Unfortunately, when steps are taken to increase one property of the product, other properties of the product are often adversely affected.

[0004] Inventors have long attempted to balance the level of softwood fiber in their paper structures to ensure sufficient strength of their structures, while at the same time minimizing the adverse effects from higher levels of softwood fiber.

[0005] One example of the problem is demonstrated by the efforts that paper toweling product formulators have made and are working to develop new products with higher in-use wet strength while maintaining or reducing dry strength. However, as formulators use typical paper machine process variables to increase the in-use wet strength of the product, other consumer-desired attributes, such as absorbency and / or softness, typically decrease. The problem formulators address to improve paper toweling is how to increase the in-use wet strength of the towel while maintaining or improving softness and / or absorbency, and / or decrease the softwood content while maintaining or reducing the total product dry strength and increasing sheet softness. All of the standard paper machine process variables that papermakers can use to increase strength typically can adversely affect sheet hand and can negatively impact product absorbency.

[0006] Therefore, there remains a need for novel fibrous paper structures that further optimize the physical product performance of towel products, increasing wet strength without sacrificing softness, absorbency, and papermaking reliability. In particular, there is a need for novel fibrous paper structures that increase wet strength while maintaining or reducing dry strength. Such structures are particularly beneficial for multi-density papermaking structures, non-limiting examples of which are those produced by Through-Air Dried, Fabric Crepe, NTT, ATMOS, and UCTAD machine processes. Summary of the Invention

[0007] A development of the present disclosure is an absorbent towel paper product having a length of grain and a cross grain perpendicular to the direction of the paper machine on which the towel paper web is produced, wherein the absorbent towel paper product comprises two plies of absorbent towel paper webs, each web comprising: (a) from about 20% to about 90% by weight of the dry fiber basis of the towel paper web, of: i.) from about 18.5% to about 88.5% by weight of the dry fiber basis of the towel paper web (the softwood pulp fibers are optionally refined before being added to the mixture); ii.) a towel (b) a refined softwood pulp fiber blend comprising from about 0.25% to about 5.0% by weight of a cationic strengthening polymer based on the dry fiber content of the paper web; (b) from about 10% to about 55% by weight of a hardwood pulp fiber blend based on the dry fiber content of the tissue paper web; and (c) a moisture content of about 10% by weight or less, wherein the paper towel web has a mean square tensile strength in the range of from about 10 Nm / g to about 18 Nm / g; and wherein the paper web has a cross-grain wet tensile strength to cross-grain dry tensile strength ratio value in the range of from about 0.20 to about 0.50. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of a process for producing multi-density absorbent paper towels on a through-air drying paper machine for use in the present disclosure. [Figure 2] FIG. 1 is a schematic diagram of another "New Tissue Technology" ("NTT") process for producing a multi-density absorbent towel web product for use in the present disclosure. [Figure 3] FIG. 1 is a schematic diagram of the Advanced Tissue Molding System "ATMOS" process for producing multi-density absorbent towel web products for use in the present disclosure. [Figure 4] FIG. 1 is a schematic diagram of a no-creping through-air drying technology "UCTAD" process for producing a multi-density absorbent towel web product for use in the present disclosure. [Figure 5] 1 is a schematic diagram of an example embodiment of an apparatus for printing and embossing absorbent paper products. [Figure 6]FIG. 1 is a schematic diagram of an example of an infeed nip and outfeed nip embossing / printing process unit. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present disclosure relates to an absorbent towel paper product having a high wet tensile strength to dry tensile strength ratio while maintaining a dry tensile despite having a lower refining energy input to the softwood stream and while maintaining a cationic resin addition constant. The absorbent towel paper product includes two plies of an absorbent towel paper web.

[0010] Each of the paper towel webs comprises about 20% to about 90% by weight of a refined softwood pulp fiber mixture, based on the dry fiber basis of the towel paper web. The refined softwood pulp fiber mixture comprises about 18.5% to about 88.5% by weight of softwood pulp fibers, based on the dry fiber basis of the towel paper web. The softwood pulp fibers are optionally refined before being added to the mixture. The softwood pulp fiber mixture also comprises about 0.25% to about 5.0% by weight of a cationic strengthening polymer, based on the dry fiber basis of the towel paper web. The paper towel webs also comprise about 10% to about 55% by weight of a hardwood pulp fiber mixture, based on the dry fiber basis of the towel paper web. The paper towel webs contain less than about 10% by weight of moisture.

[0011] The two-ply paper towel product maintains dry strength as measured by having a mean square tensile index in the range of about 10 Nm / g to about 18 Nm / g, or a dry tensile strength in the range of about 500 N / m to about 1000 N / m. The paper towel web has improved wet strength relative to the web's dry strength as measured by having a cross-grain wet tensile strength to cross-grain dry tensile strength ratio value in the range of about 0.20 to about 0.50, preferably about 0.295 to about 0.35.

[0012] As used herein, "paper product" refers to any formed, fibrous structural product that traditionally, but not necessarily, comprises cellulose fibers. In one embodiment, the paper product of the present disclosure comprises an absorbent towel product ("paper towel product"). In other embodiments, the paper product of the present disclosure may comprise a soft sanitary tissue product.

[0013] "Absorbent towel products," as used herein, are a class of paper products designed and manufactured to meet consumer demands for liquid absorption and wet cleaning with a soft hand. Absorbent towel paper webs are manufactured using the same papermaking techniques as sanitary and decorative paper webs, but the raw materials, papermaking process settings, basis weight, and other ingredients are optimized to provide the desired consumer attributes.

[0014] The paper products of the present disclosure refer to paper products including paper tissue products or paper towel products. The disclosed paper technologies generally include, but are not limited to, conventional felt-pressed or conventional wet-pressed tissue paper, pattern-densified tissue paper, wet-creped tissue paper products, and through-air-drying tissue paper products, whether creped or uncreped. For example, the papermaking process of the present disclosure can utilize adhesive creping, wet-creping, double creping, embossing, wet-pressing, air-pressing, through-air-drying, through-air-drying with creping, through-air-drying without creping, and other steps in forming a paper web. Some examples of such techniques are disclosed in U.S. Patent Nos. 4,529,480, 5,048,589, 5,399,412, 5,129,988, 5,494,554, 5,607,551, 6,398,916, 7,744,726 and 8,388,803.

[0015] When forming a multi-layer towel product such as the product of the present disclosure, the separate plies can be manufactured from the same process or from different processes as desired. For example, in one embodiment, the towel web can be a creped through-air drying web formed using processes known in the art.

[0016] To form such a web, an endlessly moving forming fabric, suitably supported and driven by rolls, receives the layered or non-layered papermaking stock flowing from a headbox. A vacuum box is positioned directly below the forming fabric and adapted to remove water from the fibrous furnish to assist in the formation of the web. From the forming wire / fabric, the formed web is transferred by vacuum assistance or mechanical means to a second fabric, which may be wire, felt, or woven, so long as the desired topography is created in the template's structure. The use of a sheet-forming template produces a papermaking structure having multiple fiber-reinforced regions of high local basis weight interconnected with multiple local low basis weight regions. The fabric is supported for movement around a continuous path by multiple guide rolls. A pickup roll designed to facilitate transfer of the web from fabric to fabric may be included to transfer the web.

[0017] The formed web is then dried to a moisture level of less than about 10% by weight moisture, preferably less than about 6% by weight moisture, and more preferably less than about 4% by weight moisture. Preferably, the formed web is dried by blowing heated air through the formed web and then transferring it to the surface of a rotatable heated dryer drum, such as a Yankee dryer. The drying cylinder is optionally provided with a resinous protective coating layer beneath the resinous adhesive coating composition. The resinous adhesive coating composition is preferably rewettable. The process is operated so that the adhesive coating provides sufficient wet tack strength upon transfer of the web to the drying cycle to secure the web during drying. The adhesive resin coating composition also maintains flexibility when dried so that the web can be removed from the drying cylinder without significant sheet damage once dryness is achieved. The web may be transferred directly from the through-drying fabric to the Yankee if the drying fabric has a topography, or preferably, transferred to an impression fabric, which is then used to transfer the web to the Yankee dryer. The web is then removed from the dryer drum by a creping blade. Creping the web further reduces internal bonding within the web, increasing softness and absorbency.

[0018] In other embodiments, the base web is formed by a non-creping through-air drying process. Related non-creping through-air drying tissue processes are described, for example, in U.S. Patent Nos. 5,656,132 and 6,017,417.

[0019] Fibrous structures according to the present disclosure may be in the form of through-air dried fibrous structures, differential density fibrous structures, differential basis weight fibrous structures, wet-laid fibrous structures, air-laid fibrous structures, creped or uncreped fibrous structures, pattern-densified or non-pattern-densified fibrous structures, compressed or uncompressed fibrous structures, double recreped fibrous structures (well known in the art and exemplified in U.S. Pat. Nos. 3,301,746, 3,974,025, 4,191,609 and 4,637,859, 6,398,906 and 8,388,803).

[0020] The absorbent towel paper web of the present disclosure has a longitudinal grain and a cross grain perpendicular to the longitudinal grain. "Mach-de-sieve" (MD) and "cross-de-sieve" (CD) are defined herein as follows: The "longitudinal grain" of a paper web is the direction in the plane of the paper web that is parallel to the length of the paper machine. The "cross-de-sieve" of a paper web is the direction in the plane of the paper web that is perpendicular to the length of the paper machine and is therefore perpendicular to the longitudinal grain. The total dry tensile is the sum of the longitudinal and cross-de-sieve tensiles.

[0021] As used herein, the phrase "papermaking furnish" refers to an aqueous mixture of either cellulosic or non-cellulosic fibers, papermaking performance aids (strength, absorbency, or softness improvement), fillers, and other papermaking process materials used to form a papermaking web. Cellulosic fibers contemplated are standard "commercially available" materials sold as softwood pulp fibers, e.g., bleached softwood kraft, hardwood pulp fibers, e.g., bleached hardwood kraft, non-wood fibers, recycled fibers, synthetic polymer fibers, and / or eucalyptus bleached kraft pulp, and do not include fibrous materials modified to enhance surface bonding properties, such as enhanced carboxylated fibers as taught in Patent 6,379,494 or similar methods of fiber modification.

[0022] The absorbent towel paper web of the present disclosure comprises from about 20% to about 90%, preferably from about 30% to about 80%, more preferably from about 40% to about 70%, and even more preferably from about 50% to about 60% of a refined softwood pulp fiber blend comprising softwood pulp fibers and a cationic strengthening polymer.

[0023] As used herein, the phrase "weight percent (%) on a dry fiber basis" refers to the percentage of the referenced material component, including any carrier and / or delivery vehicle, to the dry final fiber web once all water and other volatile materials have been removed from the papermaking web.

[0024] "Fiber," as used herein, refers to an elongated physical structure whose apparent length significantly exceeds its apparent diameter, i.e., having a length-to-diameter ratio of at least about 10 and less than 200. Fibers having non-circular cross-sections and / or tubular shapes are common; the "diameter" in this case can be considered to be the diameter of a circle having a cross-sectional area equal to the cross-sectional area of ​​the fiber. More specifically, as used herein, "fiber" refers to fibers that make up fibrous structures. The present disclosure contemplates the use of fibers that make up various fibrous structures, such as, by way of example, natural fibers, e.g., cellulose nanofilaments and / or wood pulp fibers, non-wood fibers, or any suitable fibers and any combination thereof.

[0025] Fibers that make up the natural fibrous structures useful in the present disclosure include animal fibers, mineral fibers, plant fibers, man-made spun fibers, and engineered fibrous elements, such as cellulose nanofilaments. Animal fibers can be selected from the group consisting of, for example, wool, silk, and mixtures thereof. Plant fibers can be derived from plants selected from the group consisting of, for example, wood, cotton, cotton linters, flax, sisal, abaca, hemp, hesperaloe, jute, bamboo, bagasse, espera grass, straw, jute, hemp, milkweed fluff, kudzu, corn, sorghum, gourd, agave, trichomes, loofah, and mixtures thereof.

[0026] Wood fibers, often referred to as wood pulp, are liberated from their source by any one of a number of chemical pulping processes well known to those skilled in the art, including kraft (sulfate), sulfite, polysulfide, soda pulping, etc. Additionally, fibers may be liberated from their source using mechanical and semi-chemical processes, including, for example, logwood, thermomechanical pulp, chemomechanical pulp (CMP), chemi-thermomechanical pulp (CTMP), alkaline peroxide mechanical pulp (APMP), and neutral semi-chemical sulfite pulp (NSCS), which are also contemplated. Pulp may be whitened, if desired, by any one or combination of processes well known to those skilled in the art, including the use of chlorine dioxide, oxygen, alkaline peroxides, etc. However, chemical pulps may be preferred because they impart superior hand and / or desirable tissue sheet properties. Pulp derived from both deciduous trees (hereinafter referred to as "hardwood") and coniferous trees (hereinafter also referred to as "softwood") may be used, and / or fibers derived from non-woody plants may be used together with artificial fibers. Hardwood, softwood, and / or non-woody fibers may be blended, or alternatively, deposited in layers to provide a layered and / or stratified web. U.S. Patent Nos. 4,300,981 and 3,994,771 disclose the layering of softwood and hardwood fibers. Fibers derived from recycled paper, as well as other non-fibrous materials, such as adhesives used to facilitate the original papermaking and paper processing, are also applicable to the present disclosure. Wood pulp fibers may be short (typical of hardwood fibers) or long (typical of softwood fibers and some non-woody fibers).

[0027] Examples of softwood fibers that can be used in the paper towel web of the present disclosure include, but are not limited to, fibers derived from pine, spruce, fir, larch, hemlock, cypress, and cedar. Softwood fibers derived from the Kraft process and resulting from more northern climates may be preferred. These are often referred to as Northern Bleached Softwood Kraft (NBSK) pulp.

[0028] The softwood pulp fiber mixture of the absorbent towel paper web of the present disclosure comprises from about 18.5% to about 88.5% by weight, preferably from about 25% to about 75% by weight, more preferably from about 35% to about 65% by weight, and even more preferably from about 45% to about 55% by weight softwood pulp fibers, based on the dry fiber basis of the towel paper web.

[0029] The softwood pulp fibers may optionally be treated to enhance bonding prior to addition to the softwood pulp fiber mixture. This fiber preparation may include a mechanical refining treatment, whereby the fibers are compressed and / or subjected to high shear to make the fibers softer and produce increased fiber-to-fiber bonding area due to fiber fibrillation, fiber swelling, and increased fiber flexibility. Refining may be carried out by any means known to those skilled in the papermaking art. It has been unexpectedly found that mechanical refining may be less than about 20 kilowatt-hours per bone dry ton (kWh / bdt), preferably less than about 10 kWh / bdt, and more preferably, the fibers may be unrefined and still provide enhanced wet strength, maintain constant chemical loading, and maintain paper web dry strength.

[0030] Optional treatment to enhance fiber bonding is accomplished by chemical treatment or "chemical refining" as known in the pulp and papermaking arts to increase fiber-to-fiber bonding area through fiber fibrillation, fiber swelling, and thereby also increasing fiber flexibility.

[0031] Non-limiting examples of short hardwood fibers include fibers from a fiber source selected from the group consisting of acacia, eucalyptus, maple, oak, aspen, birch, cottonwood, alder, ash, cherry, elm, hickory, poplar, rubber, walnut, black locust, sycamore, beech, catalpa, sassafras, gmelin, albizia, and magnolia.

[0032] The absorbent towel paper web comprises a hardwood pulp fiber blend comprising from about 10% to about 55%, preferably from 20% to about 45%, and more preferably from about 30% to about 40% hardwood pulp.

[0033] Different embodiments of the absorbent towel paper web of the present disclosure may also include additional pulp fibers, so long as their individual surfaces are not altered.

[0034] Recycled fibers can be added to the furnish in any amount. Any suitable recycled fiber can be used, although recycled fibers having relatively low levels of groundwood pulp are often preferred, for example, recycled fibers having a lignin content of less than 15% by weight, or less than 10% by weight, may be preferred depending on the furnish mixture and application used.

[0035] "Synthetic polymer fiber" and similar terms refer to fibers produced from synthetic polymers, such as polyesters, nylons, and polyolefins. Polyesters are generally obtained from aliphatic or aromatic dicarboxylic acids and saturated aliphatic or aromatic diols by known polymerization techniques. Preferred aromatic diacid monomers are lower alkyl esters, such as the dimethyl esters of terephthalic or isophthalic acid. Typical aliphatic dicarboxylic acids include adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, or 1,4-cyclohexanedicarboxylic acid. Preferred aromatic dicarboxylic acids, or their esters or anhydrides, are esterified or transesterified and polycondensed with saturated aliphatic or aromatic diols. Typical saturated aliphatic diols include preferably lower alkane-diols, such as ethylene glycol. Typical alicyclic diols include 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol. Typical aromatic diols include aromatic diols such as hydroquinone, resorcinol, and naphthalenediol isomers (1,5-; 2,6-; and 2,7-). Various mixtures of aliphatic and aromatic dicarboxylic acids and saturated aliphatic and aromatic diols can also be used. Most typically, aromatic dicarboxylic acids are polymerized with aliphatic diols to produce polyesters, such as polyethylene terephthalate (terephthalic acid + ethylene glycol). In addition, aromatic dicarboxylic acids can be polymerized with aromatic diols to produce wholly aromatic polyesters, such as polyphenylene terephthalate (terephthalic acid + hydroquinone).Examples of polyesters include polyethylene terephthalate; poly(1,4-butylene) terephthalate; and 1,4-cyclohexylene dimethylene terephthalate / isophthalate copolymers, and aromatic dicarboxylic acids such as isophthalic acid, bibenzoic acid, naphthalene dicarboxylic acids such as 1,5-, 2,6-, and 2,7-naphthalene dicarboxylic acids; 4,4-diphenylene dicarboxylic acid; bis(p-carboxyphenyl)methanoic acid; ethylene bis-p-benzoic acid; 1,4-tetramethylene bis(p-oxybenzoic acid); ethylene bis(p-tetramethylene acid); 1,3-trimethylene bis(p-oxybenzoic acid); and 1,4-tetramethylene bis(p-oxybenzoic acid), as well as 2,2-dimethyl-1,3-propanediol; cyclohexanedimethanol and compounds of the general formula HO(CH). n aliphatic glycols of OH (where n is an integer from 2 to 10), such as diols selected from the group consisting of ethylene glycol; 1,4-tetramethylene glycol; 1,6-hexamethylene glycol; 1,8-octamethylene glycol; 1,10-decamethylene glycol; and 1,3-propylene glycol; and diols of the general formula HO(CHCHO) n Polyethylene glycols of H (where n is an integer from 2 to 10,000), and other linear homopolymer esters derived from aromatic diols such as hydroquinone, resorcinol, and the isomers of naphthalenediol (1,5-; 2,6-; and 2,7). One or more aliphatic dicarboxylic acids, such as adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, or 1,4-cyclohexanedicarboxylic acid, may also be present.

[0036] Suitable polyolefin resins include materials produced by conventionally polymerizing olefins such as ethylene, propylene, butene-1, and pentene-1,4-methylpent-1-ene. Useful polyolefins for fibers are high-density polyethylene (HDPE) and polypropylene. Other polyolefin homopolymers and copolymers of ethylene may be used in the practice of this disclosure. Such other polyolefins include low-density polyethylene (LDPE), very low-density polyethylene (VLDPE), linear low-density polyethylene (LLDPE), and polybutylene (PB). However, these other polyolefins may be blended with other polyolefins, such as polypropylene or high-density polyethylene (HDPE).

[0037] Nylon or polyamide resins useful in the practice of the disclosure are well known in the art and include semi-crystalline and amorphous resins, which may be produced, for example, by the condensation polymerization of equimolar amounts of diamines and saturated dicarboxylic acids containing 4 to 12 carbon atoms, by ring-opening polymerization of lactams, or by copolymerization of polyamides with other components to form, for example, polyether-polyamide block copolymers. Examples of polyamides include polyhexamethylene adipamide (nylon 66), polyhexamethylene azelamide (nylon 69), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecanoamide (nylon 612), polydodecamethylene dodecanoamide (nylon 1212), polycaprolactam (nylon 6), polylaurinlactam, poly-11-aminoundecanoic acid, and copolymers of adipic acid, isophthalic acid, and hexamethylenediamine.

[0038] Synthetic polymer fibers are generally hydrophobic compared to cellulose and lack anionic sites for bonding to wet strength resins or sufficient hydroxyl groups to effectively hydrogen bond to pulp-derived fibers. Suitable fibers for use in connection with this disclosure include melt-spun fibers, melt-blown fibers, splittable fibers having multiple segments, and splittable bicomponent fibers, among others, that can be split into their segments by refining in a disc refiner. One suitable fiber available from Fiber Innovation Technology is a 16-segment, 2-denier nylon / polyester bicomponent fiber having a characteristic fineness of 0.125 denier, described below.

[0039] Splittable fiber preparation to produce splittable fibers is generally known in the context of thermoplastic fibers, where the fiber has segments formed of different polymers. See, for example, U.S. Patent No. 5,759,926 to Pike et al., U.S. Patent No. 5,895,710 to Sasse et al., and U.S. Patent Application Publication No. 2003 / 0203695 (U.S. Patent Application No. 10 / 135,650) to Polanco et al.

[0040] Splittable fibers produced and utilized in connection with this disclosure may have a split pie shape, an islands-in-the-sea configuration, a side-by-side configuration, a hollow configuration, etc. See U.S. Patent No. 4,735,849 to Murakami et al., Figures 6A-6D, and U.S. Patent Application Publication No. US 2002 / 0168912 (U.S. Patent Application Serial No. 09 / 852,888), Figures 2-9. Splittable fibers are suitably disintegrated prior to incorporation into the furnish as described below.

[0041] Artificial fibers also contemplated in this disclosure are formed by using a cellulose dope prepared through multiple solvents known to those skilled in the art. The dope can be spun into fibers that can be used or further fibrillated and incorporated into absorbent sheets. Without being limited by theory, synthetic celluloses such as lyocell are contemplated, along with modified lyocells that have been reduced in size through purification and other methods to create smaller fibers and fiber segments. U.S. Patent No. 7,718,036 discloses various possible solvents and the inclusion of fibrillated roselle in tissue and towel structures.

[0042] During fiber preparation for papermaking operations, long-fiber and some short-fiber pulp undergo mechanical or chemical processing, whereby the fibers are compressed, subjected to high shear, and / or chemically treated to make them softer and to produce increased fiber-to-fiber bonding area due to fiber fibrillation, fiber swelling, and increased fiber flexibility. Those skilled in the art will recognize that the three main products of refining pulp fibers are: 1) a percentage of fibers that are completely unaffected by refining intensity and consistency; 2) a significant percentage of fibers are fibrillated, which delaminates the fiber cell walls and exposes microfibrils that remain attached to the original fiber; and 3) a percentage of fibers and microfibrils are cut or mechanically broken into very small pieces (less than 200 microns in length); this fraction is referred to as the ultrafine fiber fraction. These ultrafine fibers can be primary (those present in natural wood sources) or secondary (those created during the refining process). What was discovered was that by varying the refining intensity, concentration and other processing conditions, new fiber components called cellulose nanofilaments could be created, and by optimizing the processing steps and unit operations, a final pulp fiber stream containing more than 40% individualized cellulose nanofilaments could be produced.

[0043] These "cellulose nanofilaments" may be used in embodiments of the present disclosure. They may be derived from either softwood and / or hardwood and, as such, may contain fibrous elements of softwood or hardwood. The cellulose nanofilament size and high aspect ratio distinguish this material as a unique fiber class and are not characterized as either softwood or hardwood materials. By high aspect ratio, we mean that the fiber length divided by the fiber width is at least 200 to about 5,000, preferably greater than about 600 to about 1,000. Cellulose nanofilaments have an average width in the nanometer range, e.g., about 30 nm to about 500 nm, and an average length in the micrometer range or greater, e.g., greater than about 10 μm, preferably about 100 μm to about 2 mm, more preferably about 200 μm to about 1 mm, and even more preferably about 300 μm to about 500 μm. Such cellulose nanofilaments can be obtained, for example, from processes that use only mechanical means, such as the method disclosed in U.S. Patent Application Publication No. 2013 / 0017394, filed January 19, 2012. Additionally, cellulose nanofilaments can be produced from a variety of processes, so long as a specific geometric shape is maintained. Processes used to make cellulose nanofilaments include, but are not limited to, modified refining equipment, homogenizers, ultrasonic fiber treatment, and chemical fiber treatment, including enzyme fiber modification.

[0044] In the article "Nanocellulose Patent Trends: A Comprehensive Review on Patents on Cellulose Nanocrystals, Microfibrillated, and Bacterial Cellulose," Charreau et al., Nanotechnology, 2013, 7, 56-80, the authors review the various terms that have been used to refer to microfibrillated cellulose (MFC) over the years, and "cellulose nanofilament" can apply to these general terms. The "cellulose nanofilament" material of the present disclosure is specifically the result of the process disclosed in publication US20130017394A1 to Hua, X. et al., entitled "High aspect ratio cellulose nanofilaments and method for their production." The material produced by this process is unique in that the disclosed process produces cellulose nanofilaments with a significantly higher aspect ratio (length / width) than previously disclosed materials.

[0045] Cellulose nanofilaments are structurally very different from other cellulose fibers, such as microfibrillated cellulose (MFC) or nanofibrillated cellulose (NFC), prepared using other methods for mechanical degradation of wood pulp fibers, in that they contain at least 40%, preferably 75%, and more preferably 90% by weight of fibrillated cellulose material filaments with a maximum filament length of 300-350 μm and a diameter of approximately 100-500 nm. The fibrillated cellulose material in NFC typically has a length of less than 100 μm, while the fibrillated cellulose material in NFC typically has a length of less than 1 μm. However, it should be recognized by those skilled in the art that similar fibrillated cellulose materials produced using mechanical means are not homogeneous materials with a single dimensional value in the production of cellulose nanofilament materials. The preferred blends of cellulose nanofilament materials and purified pulp streams containing >50% cellulose nanofilaments within the purified pulp stream described above are the basis of this disclosure.

[0046] Another anticipated application of cellulose nanofilaments possible with embodiments contemplated in this disclosure is the inclusion of a small percentage of either pure cellulose nanofilaments and / or a mixture of cellulose nanofilaments and other refined products into virgin or recycled pulp streams before transport to the papermaking site. In this way, a virgin fiber source can be augmented with cellulose nanofilaments, and the cellulose nanofilaments can then be added to the papermaking process without introducing a new fiber dosing stream. Dosing cellulose nanofilaments with cellulose at the pulp production facility could produce what has been called a "superpulp" with properties only possible through cellulose nanofilament inclusion. Therefore, many different methods for cellulose monofilament inclusion are contemplated in this disclosure, including, but not limited to, direct pure cellulose nanofilament inclusion with a mixture of cellulose nanofilaments and other refinery by-products (with a preferred nanocellulose content greater than 50%), or cellulose nanofilaments added by inclusion in virgin or recycled fibers prior to inclusion at the paper mill.

[0047] The phrase "fibrillated cellulose fibers," as used herein, refers to cellulose fibers that have undergone a mechanical or chemical treatment during which individual cellulose filaments or bundles thereof are liberated from the fiber body but remain attached to the fiber at one end, creating a larger bonding area and increased fiber-to-fiber contact. The extent of the treatment determines the number of cellulose nanofilaments released from the fiber.

[0048] As used herein, the phrase "non-cellulosic fibers" refers to a group of papermaking fibers composed of either natural or artificial fibers composed of materials other than cellulose. Non-cellulosic fibers include, but are not limited to, man-made spun fibers, fibers of animal origin, and / or microalgae. Additionally, the fibers forming the products of the present disclosure may be spun from a polymer melt composition via a suitable spinning operation, such as meltblowing and / or spinbonding, and / or they may be obtained from natural sources. Such fibers may be monocomponent and / or multicomponent. For example, the fibrous elements may include bicomponent fibers and / or filaments. The bicomponent fibers and / or filaments may be in any form, such as side-by-side, sheath-core, islands-in-sea, etc. Non-limiting examples of filaments include meltblown and / or spunbonded filaments. Non-limiting examples of polymers that can be spun into filaments include natural polymers such as starch, starch derivatives, celluloses such as rayon and / or lyocell, and cellulose derivatives, hemicellulose, hemicellulose derivatives, and synthetic polymers, including, but not limited to, thermoplastic polymer filaments such as polyester, nylon, polyolefins such as polypropylene filaments, polyethylene filaments, and biodegradable thermoplastic fibers such as polylactic acid filaments, polyhydroxyalkanoate filaments, polyesteramide filaments, and polycaprolactone filaments. Non-limiting examples of fibers include pulp fibers, such as wood pulp fibers, and synthetic staple fibers such as polypropylene, polyethylene, polyester, their copolymers, rayon, glass fiber, and polyvinyl alcohol fibers. Staple fibers can be produced by spinning a filament tow and then chopping two of the tows into segments less than 5.08 cm (2 in.) long to produce fibers.

[0049] As used herein, the phrase "cellulose microfiber" refers to a class of fibrous materials having a length of less than 200 microns. These materials may include primary materials in trees, or materials of natural origin, or they may be classified as secondary, produced either by pulping and / or handling of pulp fibers, and therefore may contain fiber sections and / or cellulose nanofilament sections. Microfiber is not a homogeneous material, but is merely used to describe a class of materials with a defined length limit.

[0050] Preferred embodiments of the absorbent towel paper web of the present disclosure comprise from about 0.05 to about 20.0%, preferably from about 1.0% to about 10.0%, and more preferably from about 1.0% to about 3.0% cellulose nanofilaments.

[0051] Cationic reinforcing polymers useful in this disclosure include, but are not limited to, cationic water-soluble resins. These resins impart wet strength to paper sheets and are well known in the papermaking art. Such resins include polyamide epichlorohydrin (PAE), urea-formaldehyde resins, melamine formaldehyde resins, polyacrylamide resins, dialdehyde starch, and mixtures thereof.

[0052] In some embodiments, other strength agents can be used to further enhance the strength of the tissue product. As used herein, a "wet strength agent" is any material that, when added to pulp fibers, can provide the resulting web or sheet with a wet geometric tensile strength to dry geometric tensile strength ratio greater than about 0.1. Typically, these are referred to as "permanent" or "temporary" wet strength agents. As is well known in the art, temporary and permanent wet strength agents can sometimes also function as dry strength agents, enhancing the strength of the tissue product when dry. The list of optional chemical ingredients is intended to be largely exemplary in nature and is not meant to limit the scope of the present disclosure. Other materials may also be included as long as they do not interfere with or diminish the benefits of the present disclosure.

[0053] Wet strength agents can be applied in various amounts depending on the desired properties of the web. For example, in some embodiments, the total wet strength agent added can be about 0.5 to 50 kg / T, in some embodiments, 2 to about 15 kg / T, and in some embodiments, about 3 to about 5 kg / T of strength agent can be incorporated into any layer of a multi-layer tissue web. Cationic wet strength resins useful in this disclosure include, but are not limited to, cationic water-soluble resins. These resins impart wet strength to paper sheets and are well known in the papermaking art. These resins can impart either temporary or permanent wet strength to fibrous sheets. Such resins include polyamide epichlorohydrin (PAE), urea-formaldehyde resins, melamine formaldehyde resins, polyacrylamide resins, dialdehyde starch, and mixtures thereof.

[0054] Strength additives may be selected from the group consisting of permanent wet strength resins, temporary wet strength resins, dry strength additives, and mixtures thereof. If permanent wet strength is desired, the chemical papermaking additives may be selected from the following group of chemicals: polyamide epichlorohydrin, polyacrylamide, insolubilized polyvinyl alcohol; ureaormaldehyde; polyethyleneimine; and chitosan polymers. Polyamide epichlorohydrin resins are cationic wet strength resins and have been found to be particularly useful. Suitable types of such resins are described in U.S. Patent Nos. 3,700,623, issued October 24, 1972, and 3,772,076, issued November 13, 1973 (both to Keim). One commercial source of useful polyamide-epichlorohydrin resins is Solenis LLC. of Wilmington, Del., which markets such resins under the trade name KYMENE® 557H.

[0055] Polyacrylamide resins have also found utility as wet strength resins. These resins are described in U.S. Patent No. 3,556,932, issued January 19, 1971, to Coscia et al., and U.S. Patent No. 3,556,933, issued January 19, 1971, to Williams et al. One commercial source of polyacrylamide resins is Kemira Oyj of Helsinki, Finland, which markets one such resin as Fennorez.

[0056] Still other water-soluble cationic resins that find utility in this disclosure are urea-formaldehyde and melamine-formaldehyde resins. The more common functional groups in these multifunctional resins are nitrogen-containing groups, such as amino groups and methylol groups attached to the nitrogen. Polyethyleneimine-type resins may also find utility in this disclosure.

[0057] When temporary wet strength is desired, the chemical papermaking additives can be selected from the following group of chemicals: cationic dialdehyde starch-based resins (e.g., Caldas produced by Japan Carlet, National Starch 78-0080, or Cobond 1000, both produced by National Starch and Chemical Corporation); and dialdehyde starch. Modified starch temporary wet strength resins are also described in U.S. Pat. No. 4,675,394, issued June 23, 1987, to Solarek et al. Preferred temporary wet strength resins include those described in U.S. Pat. No. 4,981,557, issued January 1, 1991, to Bjorkquist. Another example of a preferred temporary wet strength resin is a commercially available modified polyacrylamide resin manufactured by Fennorez, Kemira Oyj, Helsinki, Finland. When dry strength is desired, the chemical papermaking additives can be selected from the following group of chemicals. Polyacrylamide (e.g., a combination of Cypro 514 and ACCOSTRENGTH 711 produced by American Cyanamid of Wayne, NJ); starch (e.g., corn starch or potato starch); polyvinyl alcohol (e.g., AIRVOL 540 produced by Air Products Inc. of Allentown, Pa.); guar or locust bean gum; and / or carboxymethylcellulose (e.g., Calexes from CPKelco, Atlanta, GA). Generally, starches suitable for practicing the present disclosure are characterized by water solubility and hydrophilicity. Exemplary starch materials include corn starch and potato starch, although this is not intended to limit the scope of suitable starch materials; and waxy corn starch, commercially known as amioca starch, is particularly preferred. Amioca starch differs from common corn starch in that it is entirely amylopectin, whereas common corn starch contains both amylopectin and amylose.The various unique properties of Amioca starch are further described in "Amioca - The Starch From Waxy Corn," H.H. Schopmeyer, Food Industries, December 1945, pp. 106-108 (Vol. pp. 1476-1478). The starch may be in granular or dispersed form, with the granular form being preferred. The starch is preferably thoroughly cooked to induce granular swelling. More preferably, the starch granules are swollen by cooking to a certain extent just prior to dispersion of the starch granules. Such highly swellable starch granules are referred to as "fully cooked." Conditions for dispersion generally vary depending on the size of the starch granules, the crystallinity of the granules, and the amount of amylose present. Fully cooked Amioca starch can be prepared, for example, by heating an aqueous slurry of starch granules at about 4% concentration at about 190°F (about 88°C) for about 30 to about 40 minutes. Other exemplary starch materials that can be used include modified cationic starches, such as those available from National Starch and Chemical Company (Bridgewater, NJ), which have been modified to have nitrogen-containing groups, e.g., amino groups and methylol groups attached to the nitrogen. Such modified starch materials have been used primarily as pulp furnish additives to increase wet and / or dry strength. However, when applied to tissue paper webs according to this disclosure, they may have a reduced effect on wet strength compared to wet-end additions of the same modified starch material. Given that such modified starch materials are more expensive than unmodified starch, the latter has generally been preferred. These wet and dry strength resins can be added to the pulp furnish in addition to being added by the processes described in this disclosure. It should be understood that the addition of chemical compounds, such as the wet strength and temporary wet strength resins described above, to the pulp furnish is optional and not required for the practice of the present development.

[0058] In preferred embodiments of the processes of the present disclosure, the cationic reinforcing polymer is added to the furnish in an amount ranging from about 0.25% to about 5.0%, preferably from about 0.5% to about 3.0%, and more preferably from about 1.0% to about 2.0%, by weight of the resulting absorbent towel or sanitary tissue product on a dry fiber basis. Generally, processes for making absorbent towel products add higher levels of polymer, where the polymer is added at up to about 5.0%, preferably up to about 3.0%, and more preferably up to about 1.5%. Conversely, processes for producing sanitary tissue products add slightly lower levels of reinforcing polymer, where the polymer is added at up to about 3.0%, preferably up to about 1.5%.

[0059] It is understood and contemplated in this disclosure that polymers and polymer solutions may be produced now or in the future that have higher concentrations or activity levels than those currently available to paper manufacturers, and which may be embodiments that would be equivalent to absorbent towel paper webs at levels below the lower limits disclosed in this disclosure.

[0060] The fibrous structures of the present disclosure may be homogeneous or layered. If layered, the fibrous structures may comprise at least 2 and / or at least 3 and / or at least 4 and / or at least 5 layers.

[0061] "Weight" is defined herein as lbs / 3000ft 2 or g / m 2 The basis weight is the weight per unit area of ​​the sample reported in swatches. The fibrous towel structures and / or sanitary tissue products of the present disclosure may exhibit a basis weight of from 10 g / m to about 120 g / m and / or from about 14 g / m to about 80 g / m and / or from about 20 g / m to about 60 g / m.

[0062] The weight is calculated based on a certain area (m 2and weighing the sample(s) of fibrous structures and / or paper products comprising such fibrous structures according to the present disclosure on a top-loading balance having a minimum resolution of 0.01 g. The balance is protected from air currents and other hazards with a draft shield.

[0063] The weight is recorded when the balance reading is constant. The average weight (g) and average area (m) of the sample are recorded. 2 ) is calculated. 2 ) is the average weight (g) of the sample and the average area (m 2 ) is calculated by dividing by

[0064] "Sanitary products" as used herein refer to soft, low density (i.e., about 0.15 g / cm) wipes useful as wipes for urination and post-defecation cleaning (toilet paper), ENT delivery (facial tissue), and multi-functional absorbent and cleaning applications (absorbent towels). 3 Sanitary tissue products prepared according to the present disclosure may be subjected to any suitable post-processing, such as, but not limited to, printing, embossing, calendaring, slitting, folding, combining with other fibrous structures and / or winding.

[0065] In a preferred embodiment of the absorbent towel paper web of a towel paper product, the fibrous structure comprises about 20% to 90% (weight percent) of a refined softwood pulp fiber blend. The long-fiber softwood pulp fiber blend comprises about 18.5% to about 88.5% softwood pulp by weight of the towel product's dry fiber basis, where the softwood pulp is optionally refined or unrefined before combining with the cationic strength polymer. The cationic strength polymer is added to the aqueous stream to allow about 0.25% to about 5.0% by weight of the polymer to be added to the papermaking furnish. After combining the softwood pulp and cationic polymer, about 0.05% to about 20% by weight of cellulose nanofilaments by weight of the towel paper web's dry fiber basis are blended into the stream. In this embodiment of the disclosure, the softwood fibers, cellulose nanofilaments, and cationic stream are then blended with a 10% to 55% by weight, dry fiber basis, hardwood pulp fiber mixture of a towel product and formed into a fibrous sheet by any of the processes described above. The two-ply absorbent towel paper has a mean square tensile index of about 11 Nm / g to about 18 Nm / g, a total dry tensile strength value in the range of about 500 N / m to about 1000 N / m, and a cross-grain wet tensile strength to cross-grain dry tensile strength ratio of about 0.20 to about 0.50.

[0066] In another embodiment of the present disclosure, a softwood fiber stream is fed into one or more separate layers of a papermaking system and separated from 10 to 55 weight percent of a hardwood pulp fiber stream. This process embodiment produces a higher strength absorbent towel web product having a mean square tensile index of about 11 Nm / g to about 18 Nm / g and a cross-grain wet tensile strength to cross-grain dry tensile strength ratio of about 0.20 to about 0.50.

[0067] The absorbent paper towel web of the present application also includes a cationic strength polymer. Generally, the cationic strength polymer may be applied in various amounts depending on the desired properties of the web. For example, in some embodiments, the total wet strength agent added may be from about 0.5 to 50 kg / T, in some embodiments, from 2 to about 15 kg / T, and in some embodiments, from about 3 to about 5 kg / T. The strength polymer may be incorporated into any layer of the multi-layer tissue web.

[0068] Optional Ingredients - Chemical Papermaking Additives: If desired, various chemical additive compositions may be optionally added to the absorbent paper towel web to further enhance consumer-desired benefits, such as softness, low lint, absorbency, and / or sheet softness. The chemical additives are selected from the group consisting of debonders, silicon softening additives, non-silicon softening additives, non-cationic strengthening additives, absorbency additives, and aesthetic additives.

[0069] Stripping agent Chemical release agents can also be applied to soften the web. Specifically, chemical release agents can reduce the amount of hydrogen bonding within one or more layers of the web, thereby resulting in a softer product. Depending on the desired properties of the resulting tissue product, the release agent can be applied in an amount of from 0% to about 3.0%, preferably from about 0.1 to about 2.0%, and more preferably from about 0.5 to about 1.0%, by weight of the dry fiber basis of the paper web. The release agent can be incorporated into any layer of a single- or multi-layer tissue web.

[0070] Suitable release agents for use as softener additives in the present disclosure include both cationic and non-cationic surfactants, with cationic surfactants being preferred. Non-cationic surfactants include anionic, nonionic, amphoteric, and zwitterionic surfactants. Preferably, the surfactant is substantially non-migratory in situ after the tissue paper is produced, to substantially eliminate post-production changes in the tissue paper's properties that might otherwise occur due to the inclusion of the surfactant. This can be achieved, for example, by using a surfactant with a melting temperature above temperatures normally encountered during storage, shipping, sale, and use of the disclosed tissue paper product embodiments, e.g., a melting temperature of about 50°C or higher.

[0071] The level of non-cationic surfactant applied to the tissue paper web to provide the softness / tensile benefits ranges from the minimum effective level required to impart such benefits on a constant tensile basis for the final product to about 2%: preferably, about 0.01% to about 2% of the non-cationic surfactant is retained by the web; more preferably, about 0.05% to about 1.0%; and most preferably, about 0.05% to about 0.3%. The surfactant preferably has an alkyl chain with 8 or more carbon atoms. Exemplary anionic surfactants are linear alkyl sulfonates and alkyl benzene sulfonates. Exemplary nonionic surfactants are alkyl glycosides, including alkyl glycoside esters such as CRODESTA® SL-40 (available from Croda, Inc. (New York, NY)); alkyl glycoside ethers as described in U.S. Pat. No. 4,011,389, issued March 8, 1977, to W.K. Langdon; alkyl polyethoxylated esters such as PEGOSPERSE® 200ML available from Glyco Chemicals, Inc. (Greenwich, Conn.); alkyl polyethoxylated ethers and esters such as NEODOLR25-12 available from Shell Chemical Co; sorbitan esters such as SPAN 60 from ICI America, Inc., ethoxylated sorbitan esters, propoxylated sorbitan esters, mixed ethoxylated propoxylated sorbitan esters, and polyethoxylated sorbitan alcohols such as TWEEN 60 (also from ICI America, Inc.). Alkyl polyglycosides are particularly preferred for use in the present disclosure. The above list of exemplary surfactants is intended to be merely exemplary in nature and is not meant to limit the scope of the present disclosure.

[0072] silicon When a chemical softener that functions primarily by imparting a smooth hand is desired, polysiloxanes or "silicones" can be used. Depending on the desired properties of the resulting tissue product, the silicon can be applied in an amount of 0% to about 3.0% by weight, preferably about 0.1 to about 2.0% by weight, and more preferably about 0.5 to about 1.0% by weight, based on the dry fiber weight of the paper web. The silicon can be incorporated into any layer of a single- or multi-layer tissue web. Silicon compounds suitable for use in the present disclosure are described in detail below.

[0073] The polysiloxane compound preferably has monosiloxane units of the following structure: [ka] where R1 and R2, for each individual siloxane monomer unit, can each independently be hydrogen or any alkyl, aryl, alkenyl, alkaryl, arakyl, cycloalkyl, halogenated hydrocarbon, or other radical. Any such radical can be substituted or unsubstituted. The R1 and R2 radicals of any particular monomer unit can be different from the corresponding functional group of the next adjacent monomer unit. In addition, polysiloxanes can be linear, branched, or cyclic. The R1 and R2 radicals can further independently be other silaceous functional groups, such as, but not limited to, siloxane, polysiloxane, silane, and polysilane. The R1 and R2 radicals can include any of a variety of organic functional groups, including, for example, alcohol, carboxylic acid, aldehyde, ketone, and amine, amide functional groups, with amino-functional silicone compounds being preferred. Exemplary alkyl radicals are methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, octadecyl, and the like. Exemplary alkenyl radicals are vinyl, allyl, and the like. Exemplary aryl radicals are phenyl, diphenyl, naphthyl, and the like. Exemplary alkaryl radicals are toyl, xylyl, ethylphenyl, and the like. Exemplary arakyl radicals are benzyl, α-phenylethyl, β-phenylethyl, α-phenylbutyl, and the like. Exemplary cycloalkyl radicals are cyclobutyl, cyclopentyl, cyclohexyl, and the like. Exemplary halogenated hydrocarbon radicals are chloromethyl, bromoethyl, tetrafluoroethyl, fluoroethyl, trifluoroethyl, trifluorotoyl, hexafluoroxylyl, and the like.References disclosing polysiloxanes include U.S. Pat. No. 2,826,551, issued to Geen on March 11, 1958; U.S. Pat. No. 3,964,500, issued to Drakoff on June 22, 1976; U.S. Pat. No. 4,364,837, issued to Pader on December 21, 1982; U.S. Pat. No. 5,059,282, issued to Ampulski et al. on October 22, 1991; and British Patent No. 849,433, published to Woolston on September 28, 1960. Also, Silicon Compounds, pp. 181-217, distributed by Petrarch Systems, Inc. in 1984, contains an extensive list and description of polysiloxanes in general.

[0074] strength additives The strength additive may be applied to the tissue paper web alone, simultaneously with, before, or after the addition of softening, absorbency, and / or aesthetic additives. At least an effective amount of strength additive, preferably starch, provides lint control and simultaneously increased strength upon drying compared to non-binder treatments, otherwise identical sheets are preferably applied to the sheet. Preferably, about 0.01% to about 2.0% of the strength additive, calculated on a dry fiber weight basis, is retained in the dried sheet; more preferably, about 0.1% to about 1.0% of the strength additive material, preferably starch-based, is retained.

[0075] softening additives Any surfactant other than a chemical papermaking additive emulsifying surfactant material will hereinafter be referred to as a "surfactant," and any surfactant present as an emulsifying component of an emulsified chemical papermaking additive will hereinafter be referred to as an "emulsifier." The surfactant may be applied to the tissue paper alone or simultaneously with, after, or before other chemical papermaking additives. In a typical process, the surfactant is applied to the cellulosic substrate simultaneously with the other additive(s), if other additives are present. It may also be desirable to treat the release agent-containing tissue paper with relatively low levels of binder for lint control and / or to increase tensile strength.

[0076] If a chemical emollient that functions primarily by imparting a smooth feel is desired, it can be selected from the following group of chemicals: organic materials (e.g., mineral oils or waxes, such as paraffin or carnuba, or lanolin); and polysiloxanes (e.g., compounds described in U.S. Pat. No. 5,059,282 issued to Ampulski). Polysiloxane compounds suitable for use in the present disclosure are described in detail below.

[0077] If a chemical emollient that functions primarily by plasticizing the structure is desired, it can be selected from the following group of chemicals: polyethylene glycol (eg, PEG 400); dimethylamine; and / or glycerin.

[0078] If a cationic chemical softener that functions primarily by exfoliating is desired, it can be selected from the following group of chemicals: cationic quaternary ammonium compounds (e.g., dihydrogenated tallow dimethylammonium methyl sulfate (DTDMAMS) or dihydrogenated tallow dimethylammonium chloride (DTDMAC), both produced by Witco Corporation of Greenwich, Conn.; Berocel 579 (manufactured by Eka Nobel of Stennungsund, Sweden); materials described in U.S. Pat. Nos. 4,351,699 and 4,447,294 issued to Osborn; and / or diester derivatives of DTDMAMS or DTDMAC). In particular, quaternary ammonium compounds having the formula: (R1) 4-m -N + -[R2] m X - m is 1 to 3; Each R1 is a C1-C8 alkyl group, a hydroxyalkyl group, a hydrocarbyl or substituted hydrocarbyl group, an alkoxylated group, a benzyl group, or a mixture thereof; each R2 is a C9-C 41an alkyl group, a hydroxyalkyl group, a hydrocarbyl or substituted hydrocarbyl group, an alkoxylated group, a benzyl group, or mixtures thereof; and X - is any softener-compatible anion. Preferably, each R2 is C 16 -C 18 alkyl, and most preferably each R2 is a straight chain C 18 Preferably, each R is methyl and X is alkyl. - is chloride or methyl sulfate. Optionally, the R2 substituent may be derived from a vegetable oil source. Biodegradable ester-functional quaternary ammonium salts having the following formula may also be used in the present disclosure: (R1) 4-m -N + -[(CH2) n -Y-R2] m X - Each Y=-O-(O)C-, or -C(O)-O-; m=1 to 3; preferably, m=2; each n=1 to 4; preferably, n=2; Each R1 substituent is a short chain C1-C6, preferably C1-C3, alkyl group, e.g., methyl (most preferred), ethyl, propyl, etc., hydroxyalkyl group, hydrocarbyl group, benzyl group, or mixtures thereof; each R2 is a long chain, at least partially unsaturated (IV greater than about 5 to less than about 100, preferably about 10 to about 85), C 11 -C 23 a hydrocarbyl or substituted hydrocarbyl substituent, and a counterion, X - is any softener compatible anion, such as acetate, chloride, bromide, methylsulfate, formate, sulfate, nitrate, etc. Preferably, the majority of R2 is at least 90% C 18 -C 24 More preferably, the majority of R2 is at least 90% C 18 , C 22 and mixtures thereof.

[0079] Other types of suitable quaternary ammonium compounds are described in European Patent No. 0688901A2, published December 12, 1995, assigned to Kimberly-Clark Corporation.

[0080] Tertiary amine softening compounds may also be used in the present disclosure. Examples of suitable tertiary amine softening agents are described in U.S. Patent No. 5,399,241, assigned to James River Corporation and issued March 21, 1995.

[0081] Absorbent additives If enhanced absorbency is desired, surfactants may be used to treat the paper web of the present disclosure. Surfactant levels, if used, may be, in one embodiment, from about 0.01% to about 2% by dry fiber weight of the tissue web. In one embodiment, the surfactant has an alkyl chain with 8 or more carbon atoms. Alternatively, cationic softener active ingredients with highly unsaturated (mono- and / or poly) and / or branched alkyl groups can significantly enhance absorbency.

[0082] If an absorbency aid is desired to enhance absorption, it can be selected from the following group of chemicals: polyethoxylates (e.g., PEG400); alkyl ethoxylated esters (e.g., PEGOSPERSE 200ML from Lonza Inc.); alkyl ethoxylated alcohols (e.g., Neodol); alkyl polyethoxylated nonylphenols (e.g., IGEPAL CO, produced by Rhone-Poulenc / GAF), ethoxylated trimethylpentanediol, and / or materials described in U.S. Pat. Nos. 4,959,125 and 4,940,513 issued to Spendel. In cases where the surfactant release agent softener reduces wetting, a wetting agent, such as a second surfactant, can be added to the application solution. For example, sorbitan stearate esters can be mixed with alkyl polyethoxylated alcohols to produce soft, wettable paper.

[0083] Water-soluble polyhydroxy compounds can also be used as absorption aids and / or humectants. Examples of water-soluble polyhydroxy compounds suitable for use in the present disclosure include glycerol, polyglycerols having a weight-average molecular weight of about 150 to about 800, and polyoxyethylenes and polyoxypropylenes having a weight-average molecular weight of about 200 to about 4000, preferably about 200 to about 1000, and most preferably about 200 to about 600. Polyoxyethylenes having a weight-average molecular weight of about 200 to about 600 are particularly preferred. Mixtures of the above polyhydroxy compounds can also be used. For example, mixtures of glycerol and polyglycerol, mixtures of glycerol and polyoxyethylene, and mixtures of polyglycerol and polyoxyethylene are useful in the present disclosure. A particularly preferred polyhydroxy compound is polyoxyethylene having a weight-average molecular weight of about 400. This material is commercially available from Union Carbide Company of Danbury, Conn., under the trade name "PEG-400."

[0084] If an absorption aid is desired to decrease the absorption rate, it can be selected from the following group of chemicals: alkyl ketene dimers (e.g., AQUAPELR 360XC Emulsion manufactured by Hercules Inc., Wilmington, Del.); fluorocarbons (e.g., Scotch Guard by 3M of Minneapolis, Minn.); hydrophobic silicones (e.g., PDMS DC-200 by Dow Coating of Midland, Mich.); fluorotelomers (e.g., ZONYL 7040 by DuPont of Wilmington, Del.); and the like.

[0085] The absorbent additive can be used alone or in combination with a strength additive. Starch-based strength additives have been found to be preferred binders for use in the present disclosure. Preferably, the tissue paper is treated with an aqueous solution of starch. In addition to reducing lint in the finished tissue paper product, low levels of starch also provide a modest improvement in the tensile strength of the tissue paper without imparting boardiness (i.e., stiffness) (which would result from the addition of high levels of starch). This also provides tissue paper with an improved strength / softness relationship compared to tissue paper strengthened by traditional methods of increasing tensile strength, such as by further refining pulp or by the addition of other dry strength additives. This result is particularly surprising because starch has traditionally been used to enhance strength at the expense of softness in applications where softness is not an important feature, such as paperboard. Additionally, starch has been used as a filler for printing and writing papers to improve surface printability.

[0086] aesthetic additives If an aesthetic additive is desired, it can be selected from the following group of chemicals: ink; dye; fragrance; opacifier (e.g., TiO2 or calcium carbonate), optical brightener, and mixtures thereof. Paper aesthetics can also be improved using the processes described in this disclosure. Ink, dye, and / or fragrance are preferably added to an aqueous composition, which is then applied to the tissue paper web. Aesthetic additives can be applied alone or in combination with wetting, softening, and / or strength additives.

[0087] The two-ply paper web of the present disclosure has a high dry tensile strength. The paper web has a mean squared tensile in the range of about 8 Nm / g to about 20 Nm / g. Preferred embodiment paper webs have a mean squared tensile in the range of about 10 Nm / g to about 18 Nm / g. When the dry tensile strengths are measured separately, the two-ply paper web of the present disclosure has a total dry tensile strength in the range of about 500 N / m to about 1000 N / m, preferably about 600 N / m to about 900 N / m, and more preferably about 700 N / m to about 800 N / m.

[0088] The single-ply paper web produced on the paper machine of the present disclosure also has a high cross-grain (CD) wet tensile strength. Single-ply embodiments of the paper web have a CD wet tensile strength in the range of about 25 N / m to about 80 N / m. Preferred embodiment paper webs have a cross-grain wet tensile strength in the range of about 30 Nm / g to about 55 Nm / g. When measured separately, the paper web of the present disclosure has a cross-grain wet tensile strength to cross-grain dry tensile strength ratio in the range of about 0.20 to about 0.50 N / m, with preferred embodiments having a CD wet tensile strength to CD dry tensile strength ratio in the range of about 0.295 to about 0.35.

[0089] Manufacturing Process In Figure 1, a twin-wire former having a papermaking headbox 1 injects or deposits a furnish, an aqueous suspension of papermaking fibers, onto a plurality of forming fabrics, such as an outer forming fabric 5 and an inner forming fabric 3, thereby forming a wet tissue web 6. The forming process of the present disclosure can be any conventional forming process known in the papermaking industry, including, but not limited to, fourdrinier, roof formers, such as suction breast roll formers, and gap formers, such as twin-wire formers and crescent formers.

[0090] As the inner forming fabric 3 rotates around the forming roll 4, a wet tissue web 6 is formed on the inner forming fabric 3. The inner forming fabric 3 functions to support and transport the newly formed wet tissue web 6 downstream in the process as the wet tissue web 6 is partially dewatered to a consistency of about 10 percent based on the dry weight of the fibers. Additional dewatering of the wet tissue web 6 can be accomplished by known papermaking techniques, such as a vacuum suction box, while the inner forming fabric 3 supports the wet tissue web 6. The wet tissue web 6 can be further dewatered to a consistency of at least about 20 percent, more specifically about 20 to about 40 percent, and even more specifically about 20 to about 30 percent.

[0091] Forming fabric 3 can generally be made from a suitable porous material, such as metal wire or polymer filaments. For example, some suitable fabrics include, but are not limited to, Albany 84M and 94M, Asten 856, 866, 867, 892, 934, 939, 959, or 937, available from Albany International (Albany, NY); Asten Synweve Design 274, all available from Asten Forming Fabrics, Inc. (Appleton, Wis.); and Voith 2164, available from Voith Fabrics (Appleton, Wis.). Forming fabrics or felts including a nonwoven base layer can also be useful, including those manufactured using extruded polyurethane foams, such as the Spectra Series from Scapa Corporation.

[0092] The wet web 6 is then transferred from the forming fabric 3 to a transfer fabric 8, during which the solids concentration is about 10 to about 40 percent, specifically about 20 to about 30 percent. As used herein, a "transfer fabric" is a fabric positioned between the forming and drying sections of the web manufacturing process.

[0093] Transfer to the transfer fabric 8 can be accomplished with the aid of positive and / or negative pressure. For example, in one embodiment, a vacuum shoe 9 can apply negative pressure so that the forming fabric 3 and transfer fabric 8 simultaneously meet and diverge at the leading edge of the vacuum slot. Typically, the vacuum shoe 9 provides pressure at a level of about 10 to about 25 inches of mercury. As noted above, the vacuum transfer shoe 9 (negative pressure) can be supplemented or replaced by the use of positive pressure from the opposite side of the web, which blows the web onto the next fabric. In some embodiments, another vacuum shoe can also be used to help draw the fibrous web 6 onto the surface of the transfer fabric 8.

[0094] Typically, the transfer fabric 8 travels at a slower speed than the forming fabric 3 to enhance the web's MD and CD stretch, which generally refers to the web's stretch in its cross-grain (CD) or long-grain (MD) direction (expressed as percent elongation at specimen break). For example, the relative speed difference between the two fabrics may be from about 1 to about 30 percent, in some embodiments from about 5 to about 20 percent, and in some embodiments, from about 10 to about 15 percent. This is commonly referred to as a "rush transfer." During a "rush transfer," many of the web's bonds are believed to be broken, forcing the sheet to flex and fold into the depressions on the surface of the transfer fabric 8. Such molding to the contours of the surface of the transfer fabric 8 can increase the web's MD and CD stretch. Rush transfer from one fabric to another can follow the principles taught in any one of the following patents: U.S. Patent Nos. 5,667,636, 5,830,321, 4,440,597, 4,551,199, and 4,849,054.

[0095] The wet tissue web 6 is then transferred from the transfer fabric 8 to the through-air drying fabric 11. Typically, the transfer fabric 8 travels at approximately the same speed as the through-air drying fabric 11. However, it has now been discovered that a second rush transfer can be performed as the web is transferred from the transfer fabric 8 to the through-air drying fabric 11. This rush transfer is referred to herein as occurring at a second location and is achieved by operating the through-air drying fabric 11 at a slower speed than the transfer fabric 8. By performing rush transfers at two separate locations, i.e., a first and second location, a tissue product with increased CD stretch can be produced.

[0096] In addition to rush transferring the wet tissue web 6 from the transfer fabric 8 to the through-air drying fabric 11, the wet tissue web 6 may be macroscopically reoriented to conform to the surface of the through-air drying fabric 11 with the aid of a vacuum transfer shoe, such as vacuum transfer roll 12 or vacuum shoe 9. If desired, the through-air drying fabric 11 can be moved at a speed slower than that of the transfer fabric 8 to further enhance the MD stretch of the resulting absorbent tissue product. Transfer may also be performed with vacuum assistance to ensure conformance of the wet tissue web 6 to the topography of the through-air drying fabric 11.

[0097] While supported by the through-air drying fabric 11, the wet tissue web 6 is dried by the through-air dryer 13 to a final consistency of about 94 percent or greater. The web 15 then passes through a winding nip between a reel drum 22 and a reel 23 and is wound into a roll 25 of tissue for subsequent processing, such as slitting, folding, and packaging.

[0098] The web is transferred, preferably with the aid of a vacuum, to a through-air drying fabric for final drying, ensuring macroscopic rearrangement of the web to impart the desired bulk and appearance. The use of separate transfer and through-air drying fabrics can provide various advantages because it allows the two fabrics to be specifically designed to independently address key product requirements. For example, the transfer fabric is typically optimized to enable efficient conversion of high-lash transfer levels to high MD stretch, while the through-air drying fabric is designed to deliver bulk and CD stretch. Therefore, it is useful to have a moderately coarse, moderately three-dimensional transfer fabric and a through-air drying fabric (which in the optimized configuration is quite coarse and three-dimensional). The result is a relatively smooth sheet exiting the transfer section, which is then macroscopically rearranged (with vacuum assistance) to impart the high-bulk, high-CD stretch surface topology of the through-air drying fabric. The sheet topology changes completely from the transfer to the through-air drying fabric, and the fibers are macroscopically rearranged, including significant fiber-to-fiber movement.

[0099] The drying process can be any non-compression or compression drying method that tends to preserve the bulk or thickness of the wet web, including, but not limited to, through-air drying, infrared radiation, microwave drying, Valmet NTT, Voith ATMOS, and the like. Due to its commercial availability and practicality, through-air drying is well-known and is one commonly used means for non-compression drying of webs for purposes of this disclosure. Suitable through-air drying fabrics include, but are not limited to, fabrics having substantially continuous longitudinal ridges, whereby the ridges are formed by holding together multiple warp yarns, such as those disclosed in U.S. Pat. No. 6,998,024. Other suitable through-air drying fabrics include those disclosed in U.S. Pat. No. 7,611,607, particularly the fabrics called Fred (t1207-77), Jeston (t1207-6), and Jack (t1207-12). The web is preferably dried to final dryness on the through-air drying fabric, without pressing it against the surface of a Yankee dryer, and without subsequent creping.

[0100] Once the wet tissue web 6 is uncompressed and dried, thereby forming a dry tissue web 15, the dry tissue web 15 can be creped by transferring the dry tissue web 15 to a Yankee dryer before winding, or by using an alternative shortening method, such as microcreping as disclosed in U.S. Pat. No. 4,919,877.

[0101] For wound products, it is often advantageous to wind the product with the softest side facing the consumer, and therefore shear processes that increase the softness of this side are preferred. However, it is also possible to treat the air side of the web rather than the fabric side, and in these embodiments, it may be possible to increase the softness of the air side to a higher level than the fabric side.

[0102] The process of the present disclosure is well suited for forming multi-ply tissue products. The multi-ply tissue product may include two, three, or more plies. In one particular embodiment, a two-ply roll tissue product is formed according to the present disclosure, where both plies are formed using the same papermaking process, such as through-air drying without creping. However, in other embodiments, the plies may be formed by two different processes. Generally, the first and second plies are attached together before being wound into a roll. Any suitable method for laminating the webs together may be used. For example, the process includes a crimping device, which mechanically attaches the plies together by fiber entanglement. However, in other embodiments, an adhesive may be used to attach the plies together.

[0103] Machining and finishing processes The absorbent towel web prepared according to the present disclosure may be subjected to any suitable post-processing, such as, but not limited to, printing, embossing, calendaring, slitting, folding, combining with other fibrous structures, etc., to form the final two-ply absorbent toweling product.

[0104] This invention relates to two-ply paper toweling, and more particularly to the combination of two differential density plies to produce a structure with a uniquely superior CD wet tensile to CD dry tensile ratio. The invention contemplates many previously taught means of joining two piles, including two smooth-outside paper towels, which are known and taught in U.S. Patent No. 1,964,700, for example; the toweling plies used in such structures are webs that are subsequently creped, embossed, and bonded with their rough sides facing to provide spaces or voids between the plies. The smooth sides provide a smooth feel and a large effective surface area against the user's skin, while the internal voids limit the rate of liquid transfer between the plies and prevent the towel from collapsing when wet. The tendency of multi-ply toweling to separate during use or upon cutting, etc., was recognized in U.S. Patent No. 1,961,914, which proposed bonding the plies only locally or at their edges with adhesive. U.S. Patent 1,786,781 teaches the application of adhesive in the toweling, which is water-absorbent, thus avoiding the repulsion of some adhesives that tend to reduce towel drying capacity. The adhesive application between plies can take many forms, such as the adhesive dots of U.S. Patent 1,786,781, or the application used in mass embossing operations, such as those described in U.S. Patent 2,978,006. Alternatively, adhesive can be applied as a size along compression lines in the toweling, thus strengthening the towel around the periphery of the absorbent towel area, as set forth in U.S. Patent 1,033,992 or produced by passing the material through a roll with small pockets, as shown in U.S. Patent 1,900,257. US Patent No. 3,708,366 A teaches us how to perform embossing operations in successive nips, with one ply being subjected to multiple embossings and a second ply being subjected to only one such operation, thereby limiting the mechanical pressing action on one terry ply as desired and thereby controlling its absorbency; also, the mechanical arrangement may be simplified to a single stack of embossing rolls and backup rolls, occupying minimal space.The product itself may include an adhesive that is applied only in a controlled area and amount, and may rely solely on the embossing action for ply adhesion if desired. The adhesive, if used, is preferably applied in a small, discrete amount to avoid hardening of the final product. Any of a number of adhesives are useful, such as polyvinyl acetate emulsions, aqueous solutions of polyvinyl alcohol, and synthetic latexes. Preferably, in this case, they are somewhat viscous and fast-drying, limiting web penetration and ensuring rapid development of the bond.

[0105] U.S. Patent No. 4,276,338 A teaches us that the essence of a towel structure is an absorbent body comprising two adjacent layers intimately joined together in a generally parallel and coextensive alignment, such that the major surface of the first layer is intimately laminated to the major surface of the second layer. The low-density regions of the first layer are aligned with the low-density regions of the second layer, thereby minimizing the percentage of overlap between the low-density regions of the individual layers. In the most preferred embodiment of the invention, the percentage of overlap between the low-density regions of the individual layers is zero. However, it is difficult to achieve a complete lack of overlap between the first and second layers of absorbent material in an operational environment. Therefore, a percentage of overlap greater than zero may be tolerated, albeit at the expense of some loss of performance. The maximum level of overlap within the scope of the present invention is defined by random orientation of the layers, in which the first and second layers are joined without regard to hole alignment and analyzed for overlap percentage. A preferred maximum level of overlap is a percentage of overlap slightly lower than that observed in randomly ordered structures. Obviously, two-layer structures in which substantially all of the low density regions overlap are outside the scope of the present invention.

[0106] Certain characteristics must be present for an absorbent article to fall within the scope of this invention. First, the major surfaces of the individual layers to be joined together must be directly adjacent to one another so that the amount of intermediate material is minimized for the invention to function properly. This does not exclude the possibility that a minimal amount of powdered "super-sorber" or the like (e.g., starch-acrylonitrile copolymer, etc.) may be placed between the layers. Lamination and gluing enable the structure to substantially retain its novel alignment during use. In one (highly preferred) version of the invention, two identical layers of sheet material are laminated to form a "double-sided" sheet, each of whose (outer) opposing major surfaces is a working surface.

[0107] In another mode of practicing the invention, two non-identical layers of material are joined together to form a laminate structure, which may have one or more working surfaces, depending on whether one or more of the outer major surfaces has the required attributes of a working surface.

[0108] Without departing from the present invention, the two-layer structure described herein may have an additional layer adjacent to its outer portion. A first example of such a layer is an additional absorbent layer on the side of the novel structure of the present invention away from its working surface to increase the structure's absorption capacity. A second example of an additional layer is a structure in which two layers of the present invention occupy the inner region of the absorbent body, such that an absorbent layer is found on the outside of each working layer of the absorbent structure of the present invention. The utility of such an arrangement of the structure of the present invention would be to distribute fluid already captured in the absorbent body. (It will be understood that, in relation to the immediately preceding embodiment, the "working surface" as defined herein need not be the outer surface of the final absorbent article.)

[0109] In another embodiment of the invention, a layer may be interposed between the working surface of the structure of the invention and the fluid to be treated with the absorbent, for example, a perforated scrim of abrasive material adjacent the working surface of the structure to increase the life and usefulness of the finished article for scrubbing surfaces.

[0110] Dissimilar materials can be joined as taught herein to provide absorbent structures with particular properties. For example, materials with different hydrophilicity or pore sizes can be joined as taught herein to produce composite materials with desired hydrophilicity or pore size gradients.

[0111] Articles having many shapes and configurations can be produced that incorporate the features of the present invention. As described above, a preferred embodiment of the invention involves two flat, generally parallel, coextensive layers that are bonded together to form a double-sided structure. However, this does not limit the range of possible configurations.

[0112] In one example, the structure of the present invention may comprise a thin sheet of material having a working surface and an opposing major surface, the latter attached to a major surface of a three-dimensional shape defining a surface that meets the layer requirements defined herein. In this case, the three-dimensional shape may be a single layer, only a portion of which (the outer surface) has the attributes of the layer required herein without departing from the scope of the present invention.

[0113] The inventive structures may be attached to a handle or other implement to perform a cleaning or wiping function without departing from the inventive structure requirements. Similarly, the inventive structures may be incorporated into one or more portions of a finished absorbent article, for example, as a series of separate regions of a wipe.

[0114] The bonding requirements of the individual layers are discussed above; the two layers central to this invention must be bonded together sufficiently to maintain most or all of the low-density regions of the structure in the desired alignment. Many bonding schemes can be devised to meet this alignment requirement without substantially reducing the absorption capacity and efficiency of the layers. In a preferred mode of practicing the invention, discontinuous bonding is used, meaning that a number of separate bonds are distributed across the interior surface of the layers, separated by regions (preferably continuous regions) of unbonded material.

[0115] Many techniques for bonding webs together to form absorbent structures are known, and therefore no attempt is made to list all such techniques. Bonding techniques that are particularly useful herein include: point bonding; thermal, ultrasonic, or radiation methods of fusion bonding; stitching, sewing, and other methods of bonding that require the use of mechanical fastening devices; needle punching, and other means. The bonded areas may be randomly (but necessarily uniformly) distributed on the layer, or may form any of the patterns described above in the description of the low-density areas.

[0116] It is important that a significant surface area of ​​the bonded layers be free of bonds to prevent loss of layer alignment. This goal has been found to be met when the following conditions are observed: The bonded area should occupy between about 2% and about 25% of the surface area of ​​the structure. The span between adjacent bond centers should be at least about 1 / 4 inch (6 mm) and not more than about 2 inches (51 mm). The span of a particular bond should be at least about 1 / 64 inch (0.40 mm) and not more than about 1 / 4 inch (6 mm).

[0117] As explained in the Background section above, absorbent structures have many uses, and therefore the present invention is useful in the manufacture of many different types of absorbent articles.

[0118] Preferred embodiments of both aspects of the invention are useful in their own right as towels or wipes that exhibit improved wicking when compared to wipes that are not aligned according to the invention.

[0119] The present invention has utility in connection with bandages and absorbent dressings. The two-layer structure of the present invention can be used as the topsheet in such devices or as a component of the absorbent material of the bandage.

[0120] Feminine products of all kinds, such as tampons, panty shields, sanitary napkins, etc., all require efficient and reliable absorption, and therefore the materials of the present invention may be used as topsheets or absorbent elements in connection with such products.

[0121] Diapers and other incontinence garments require very high absorbency to perform their intended function, but high bulk is undesirable in such garments, especially when they are worn discreetly under outer garments. Thus, the wicking benefits exhibited by the present two-layer material make it well suited for use as a diaper topsheet and as a component of a diaper absorbent core.

[0122] The improvements of the present invention may also be used in surgical drapes, garments, and other articles. Finally, the use of the present structures is not limited to disposable garments, as the techniques described herein may be equally applied to durable garments.

[0123] Figure 5 shows an example process that can be used to combine two paper webs into an embossed, perforated, two-ply finished product. The exact converting process is not critical to the disclosure, but serves as one way in which converting variations can be achieved.

[0124] The apparatus includes an unwinder unit 10 for feeding the continuous paper web to the individual production processes. In the unwinder unit 10, a parent roll 11 is unwound and fed into the individual units in the form of a continuous paper web 12. A parent roll is a large roll of paper that is converted into a plurality of individual sanitary paper products in the form of sheets or rolls. Different parent rolls have different characteristics that affect the transport of the sheets through the apparatus. In the example shown, the continuous web is first transported to a printing unit 13. Before the printing unit, i.e., upstream of the printing unit in the direction of web movement through the apparatus, an infeed nip 14 is arranged in the form of an S-wrap and is composed of two rolls 14a, 14b. Beyond the printing unit 13, i.e., downstream of the printing unit, an outfeed nip 15 is arranged in the form of an S-wrap and also has two rolls 15a and 15b. The printing unit is disposed between infeed nip 14 and outfeed nip 15 and includes four print cylinders 16, 17, 18, and 19 and one backing roll 20 for all four print cylinders. As will be apparent, printing unit 13 is a four-color printing unit and thus includes four print cylinders. However, other conventional printing unit arrangements and different numbers of colors are possible, as will be apparent to those skilled in the art. In the drawing, the continuous web is transported from unwinder unit 10 to printing unit 13; i.e., continuous web 12 moves from left to right as viewed in the drawing. Consequently, as viewed in the direction of movement of continuous web 12, infeed nip 14 is located upstream of the printing unit and outfeed nip 15 is located downstream of the printing unit.

[0125] After leaving the delivery nip 15, the web is transported to an embossing unit 21. The embossing unit 21 includes an embossing roll 22 and a respective backing roll 23. A sensor 24, which is part of a feedback control (not shown), is positioned above one surface of the web. The speed ratios of the drives for the print cylinders 16, 17, 18, 19 and the embossing cylinder 22 are adjusted, if necessary, to correct deviations. Furthermore, the drives for the embossing cylinder 22 and the print cylinders 16, 17, 18, 19 are coupled via a gearbox or a master-slave servo drive.

[0126] As will become apparent, the embossing unit 21 includes a second embossing roll 25 and a second backing roll 26. For example, a second continuous web 27 is fed to the embossing unit to be embossed and then laminated to the first continuous web 12, thus enabling the production of a multi-ply paper product. Of course, other arrangements of embossing units can be used and are well known to those skilled in the art.

[0127] After embossing, the paper web is transported to a perforation unit 28, which includes a perforation roll 29 and a backing roll 30. An additional nip point 31, including two rolls 31a and 31b, may be arranged upstream of the perforation unit 28. After perforation has been performed, the continuous web 12, or the multi-layer web 27, if two webs are stacked, is unwound by a rewinder unit 32. In this way, the final product can be provided in roll form, such as for a toilet paper roll or a kitchen towel roll. Alternatively, a cutting unit could be provided instead of the perforation unit. In this case, the final product has the form of a single sheet, such as, for example, a napkin.

[0128] Reference is now made to Figure 6, which shows schematically an arrangement of infeed nips 14 and outfeed nips 15 surrounding a single print nip 33. Print nip 33 is defined by a print roll 33a and a backing roll 33b. The drives of all three nips 14, 15, and 33 are linked, and the web speed at these nip points is the same, so the web passes through the process without any change in its tension or stretch. After exiting outfeed nip 15, the web is relaxed.

[0129] As can be seen from the corresponding speed / tension profiles shown in FIG. 5, for example, a print design having a 200 mm repeat length on a print cylinder can be printed onto a narrow web. The web is stretched between the infeed and outfeed nips, and after exiting the outfeed nip, it is relaxed again. Using a 5% stretch, a 200 mm print design printed on such a stretched web will shrink to approximately 190 mm on the web after exiting the outfeed nip 15. Thus, within the scope of elastic stretch, the system can also be used to correct for fundamental mismatches between print repeat length and any other repeat length, such as in preferred embodiments with embossing and / or perforation. As an example, a range of 0% to 5% for a typical household towel allows for adjustment of the repeat length from 0 mm to 12 mm. The stretch of the web 12 is adjusted by drives at the individual nip points. Arrows 34 indicate the direction of movement of the web 12.

[0130] Example Example 1: Absorbent terry cloth Terry cloth parent rolls obtained from a Valmet Karlstad TAD demonstrator containing cellulose nanofilaments of the present disclosure were processed on a Fabio Perini pilot processing line in Green Bay, Wisconsin. The processing line was set up with the following embossing rolls: Upper D9106pe (Perini DESL (nested) towel pattern) Lower D9235pe (Perini DESL (nested) towel pattern)

[0131] The converting line was run with set rolls to establish consistent embossing and proper adhesive addition to ensure proper lamination and web tension. The rewinder was set to towel parameters of 86 sheet count, 9.0" sheet length, 5" roll diameter, and 11" roll height to simulate laminated premium towels on the market. Testing was performed and the converted product was tested by the Institute of Paper Science Testing Company in Appleton, Wisconsin, with the following results: [Table 1]

[0132] Observations: We were not successful in holding product dry tensiles constant within product families as a result of product variations in the rolls selected for processing. Within process and test method variations, CD tensiles were not constant, ranging from 289-319 N / m for high tensile product parameters and 221-241 N / m for low tensile demonstrations; surprisingly, CD wet tensiles increased from 84.2 to 99.8 N / m and from 60-72.3 N / m, which surprisingly increased the CD wet-to-dry tensile ratio from 0.27 to 0.31. Even more surprising was the fact that wet tensiles increased as refining energy input was reduced, since it is well documented that wet tensiles generally increase with refining over standard refining control limits.

[0133] Analytical Test Methods The following test methods are representative of techniques used to determine the physical properties of the absorbent paper webs involved herein.

[0134] 1. Sample Conditioning and Preparation All samples for testing are generally prepared in a conditioning environment that conforms to accepted standards for paper testing. The conditioning environment for the samples has a constant humidity of approximately 50% and a temperature of approximately 74 degrees Fahrenheit.

[0135] 2. Total dry tensile strength The dry tensile strength properties of absorbent paper web samples of the present disclosure are determined by performing the test methods published by the International Organization for Standardization, ISO 12625-4:2005, Tissue Paper and Tissue Products - Part 4: Determination of Tensile Strength, Stretch at Break, and Tensile Energy Absorption. ISO 12625-4 is used to measure both length-of-grain (MD) and cross-grain (CD) dry tensile strengths. The total dry tensile strength is the mathematical sum of the length-of-grain dry tensile strength and the cross-grain dry tensile strength.

[0136] 3. Mean square dry tensile strength The mean square dry tensile strength index is a calculated parameter derived from ISO 12625-4 results and is equal to the square root of the MD tensile index squared plus the CD tensile index squared. The mean square dry tensile may provide a more representative metric for assessing overall sheet strength per unit mass.

[0137] 4.Wet tensile strength The wet tensile strength properties of absorbent paper web samples of the present disclosure are determined by performing the test method published by the International Organization for Standardization, ISO 12625-5:2005, Tissue Paper and Tissue Products - Part 5: Determination of Wet Tensile Strength. ISO 12625-5 is used to measure both machine-wise (MD) and cross-machine (CD) wet tensile strength.

[0138] 5. CD wet tensile:CD dry tensile ratio The characteristic ratio of grain wet tensile strength to grain dry tensile strength is calculated as the mathematical ratio of two characteristic parameters. ratio= CD wet tensile strength CD dry tensile strength

[0139] As used in this disclosure, the terms "comprises," "comprising," and other derivatives of the root term "comprises" are intended to be open-ended terms specifying the presence of any stated features, elements, integers, steps, or components, and are not intended to exclude the presence or addition of one or more other features, elements, integers, steps, components, or groups thereof.

[0140] The dimensions and values ​​disclosed herein should not be understood to be strictly limited to the exact dimensions and values ​​recited. Instead, unless otherwise specified, each such dimension and / or value is intended to mean both the recited dimension and / or value and a functionally equivalent range surrounding that dimension and / or value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm."

[0141] While particular embodiments of the present disclosure have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the disclosure. Therefore, it is intended in the appended claims to cover all such changes and modifications that are within the scope of this disclosure.

Claims

1. 1. An absorbent towel paper product having a longitudinal grain and a cross grain perpendicular to the longitudinal grain, said absorbent towel paper product comprising two plies of absorbent towel paper web, each paper web having (a) from about 20% to about 90%, by weight of the dry fiber basis of the towel paper web, of a refined softwood pulp fiber mixture comprising: i.) about 18.5% to about 88.5% softwood pulp fibers by weight of the towel paper web, on a dry fiber basis, optionally refined prior to being added to the mixture; ii.) about 0.25% to about 5.0% by weight of the tissue paper web's dry fiber basis of a cationic strength polymer; a softwood pulp fiber mixture comprising: (b) from about 10% to about 55% by weight of the tissue paper web dry fiber basis of a hardwood pulp fiber blend; and (c) less than or equal to about 10% by weight moisture; Including, the two-ply paper product has a mean squared tensile strength in the range of about 10 Nm / g to about 18 Nm / g; and the two-ply paper product has a grain wet tensile strength to grain dry tensile strength ratio value in the range of about 0.295 to about 0.33; Absorbent towel paper products.

2. 10. The absorbent towel paper web of claim 1, wherein the softwood pulp fibers are refined with a delivered energy of less than about 25 kWh / bdt.

3. 10. The absorbent towel paper web of claim 1, wherein the softwood pulp fibers are refined with a delivered energy of less than about 10 kWH / bdt.

4. 10. The absorbent towel paper web of claim 1 produced by a papermaking process that introduces density differences into the fibrous web.

5. 10. The absorbent towel paper web of claim 1, wherein the towel paper web is produced by a through-air drying papermaking process.

6. 10. The absorbent towel paper web of claim 1, wherein the towel paper web is produced by the NTT papermaking process.

7. 10. The absorbent towel paper web of claim 1, wherein the towel paper web is produced by an ATMOS process.

8. 2. The absorbent towel paper web of claim 1, wherein the papermaking process is a UCTAD drying process.

9. 1. An absorbent towel paper product having a longitudinal grain and a cross grain perpendicular to the longitudinal grain, said absorbent towel paper product comprising two plies of absorbent towel paper web, each paper web having (a) from about 20% to about 90%, by weight of the dry fiber basis of the towel paper web, of a refined softwood pulp fiber mixture; i.) about 18.5% to about 88.5% softwood pulp fibers by weight of the towel paper web, on a dry fiber basis, optionally refined prior to being added to the mixture; ii.) about 0.25% to about 5.0% by weight of the dry fiber basis of the towel paper web of a cationic strengthening polymer; a softwood pulp fiber mixture comprising: (b) from about 10% to about 55% by weight of the dry fiber basis of the towel paper web of a hardwood pulp fiber mixture; and (c) less than or equal to about 10% by weight moisture; Including, the paper web has a total dry tensile strength value in the range of about 500 N / m to about 1000 N / m; and the paper web has a cross-grain wet tensile strength to cross-grain dry tensile strength ratio value in the range of about 0.295 to about 0.33; Absorbent towel paper products.

10. 10. The absorbent towel paper web of claim 9, wherein the softwood pulp fibers are refined with a delivered energy of less than about 25 kWh / bdt.

11. 10. The absorbent towel paper web of claim 9, wherein the softwood pulp fibers are refined with a delivered energy of less than about 10 kWh / bdt.

12. 10. The absorbent towel paper web of claim 9, produced by a papermaking process that introduces density differences into the fibrous web.

13. 10. The absorbent towel paper web of claim 9, wherein the towel paper web is produced by a through-air drying papermaking process.

14. 10. The absorbent towel paper web of claim 9, wherein the towel paper web is produced by the NTT papermaking process.

15. 10. The absorbent towel paper web of claim 9, wherein the towel paper web is produced by an ATMOS process.

16. 10. The absorbent towel paper web of claim 9, wherein the papermaking process is a UCTAD drying process.

17. 1. An absorbent towel paper product having a longitudinal grain and a cross grain perpendicular to the longitudinal grain, said absorbent towel paper product comprising two plies of absorbent towel paper web, each paper web having (a) from about 20% to about 90%, by weight of the dry fiber basis of the towel paper web, of a refined softwood pulp fiber mixture; i.) about 18.5% to about 88.5% softwood pulp fibers by weight of the towel paper web, on a dry fiber basis, optionally refined prior to being added to the mixture; ii.) about 0.25% to about 5.0% by weight of the dry fiber basis of the towel paper web of a cationic reinforcement polymer; iii.) about 0.05% to about 20% by weight of the dry fiber basis of said towel paper web of cellulose nanofilaments a softwood pulp fiber mixture comprising: (b) from about 10% to about 55% by weight of the dry fiber basis of the towel paper web of a hardwood pulp fiber blend; and (c) less than or equal to about 10% by weight moisture; Including, the towel paper web has a root mean square tensile strength in the range of about 10 Nm / g to about 18 Nm / g; and the towel paper web has a cross-grain wet tensile strength to cross-grain dry tensile strength ratio value in the range of about 0.20 to about 0.50; Absorbent towel paper products.

18. 20. The absorbent towel paper web of claim 17, wherein the softwood pulp fibers are refined with a delivered energy of less than about 25 kWh / bdt.

19. 20. The absorbent towel paper web of claim 17, wherein the softwood pulp fibers are refined with a delivered energy of less than about 10 kWh / bdt.

20. 20. The absorbent towel paper web of claim 17, produced by a papermaking process that introduces density differences into the fibrous web.

21. 20. The absorbent towel paper web of claim 17, wherein the towel paper web is produced by a through-air drying papermaking process.

22. 20. The absorbent towel paper web of claim 17, wherein the towel paper web is produced by the NTT papermaking process.

23. 20. The absorbent towel paper web of claim 17, wherein the towel paper web is produced by an ATMOS process.

24. 18. The absorbent towel paper web of claim 17, wherein the papermaking process is a UCTAD drying process.

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