Cationic silicone polymer-containing fibrous structures

FIELD OF THE INVENTION

[0001] The present invention relates to a fibrous structure comprising a cationic silicone polymer comprising one or more polysiloxane units and one or more non-pendant quaternary nitrogen moieties, a process for making such a fibrous structure and a sanitary tissue product incorporating such a fibrous structure.

BACKGROUND OF THE INVENTION

[0002] It is well known in the art that the softness of a structured sanitary tissue product is inversely proportional to the total tensile strength of the structured sanitary tissue product. Further, it is well known in the art that the smoothness of a structured sanitary tissue product is inversely proportional to the caliper of the structured sanitary tissue product.

[0003] Attempts by formulators to overcome the inverse relationships, especially the softness to total tensile strength have included adding cationic silicones to sanitary tissue products and/or fibrous structures making up such products. See for example U.S. Pat. No. 5,059,282 to Ampulski et al.

[0004] However, such prior art sanitary tissue products and references fail to teach fibrous structures that incorporate a cationic silicone polymer comprising one or more polysiloxane units, one or more non-pendant quaternary nitrogen moieties and one or more of the following: alkylene oxide units; ring-opened epoxide units and alternating units of a quaternary nitrogen-containing divalent organic moiety.

[0005] Even further, the prior art fails to teach a fibrous structure wherein the fibrous structure comprises a fiber furnish layer and a cationic silicone polymer layer discrete from the fiber furnish layer, wherein the cationic silicone polymer comprises one or more polysiloxane units, one or more non-pendant quaternary nitrogen moieties and one or more of the following: alkylene oxide units; ring-opened epoxide units and alternating units of a quaternary nitrogen-containing divalent organic moiety.

SUMMARY OF THE INVENTION

[0006] The present invention overcomes the deficiencies associated with the prior art by providing a novel fibrous structure that incorporates a cationic silicone polymer.

[0007] In one aspect of the present invention, a fibrous structure comprising a fiber furnish layer and a cationic silicone layer discrete from the fiber furnish layer, wherein the cationic silicone polymer comprises one or more polysiloxane units and one or more non-pendant quaternary nitrogen moieties, is provided.

[0008] In another aspect of the present invention, a fibrous structure comprising:

[0009] a. a fiber furnish; and

[0010] b. a cationic silicone polymer selected from the group consisting of:

[0011] i. a cationic silicone polymer comprising one or more polysiloxane units, one or more non-pendant quaternary nitrogen moieties and one or more alkylene oxide units;

[0012] ii. a cationic silicone polymer comprising one or more polysiloxane units, one or more non-pendant quaternary nitrogen moieties and one or more ring-opened epoxide units;

[0013] iii. a cationic silicone polymer comprising alternating units of: a) a polysiloxane comprising one or more polysiloxane units and one or more non-pendant quaternary nitrogen moieties; and b) a quaternary nitrogen-containing divalent organic moiety; and

[0014] iv. mixtures thereof, is provided.

[0015] In yet another aspect of the present invention, a process for making a fibrous structure comprising the steps of:

[0016] a. providing a fibrous furnish;

[0017] b. depositing the fibrous furnish on a foraminous forming surface to form an embryonic fibrous web;

[0018] c. drying the embryonic fibrous web such that the fibrous structure is formed; and

[0019] d. applying a cationic silicone polymer comprising one or more polysiloxane units and one or more non-pendant quaternary nitrogen moieties to the embryonic fibrous web and/or the fibrous structure, is provided.

[0020] In still another aspect of the present invention, a single- or multi-ply sanitary tissue product comprising a fibrous structure according to the present invention is provided.

DETAILED DESCRIPTION OF THE INVENTION

[0021] “Fiber” as used herein means an elongate particulate having an apparent length greatly exceeding its apparent width, i.e. a length to diameter ratio of at least about 10. More specifically, as used herein, “fiber” refers to papermaking fibers. The present invention contemplates the use of a variety of papermaking fibers, such as, for example, natural fibers or synthetic fibers, or any other suitable fibers, and any combination thereof. Papermaking fibers useful in the present invention include cellulosic fibers commonly known as wood pulp fibers. Applicable wood pulps include chemical pulps, such as Kraft, especially Northern Softwood Kraft (“NSK”), sulfite, and sulfate pulps, as well as mechanical pulps including, for example, groundwood, thermomechanical pulp and chemically modified thermomechanical pulp. Nonlimiting examples of wood pulps include fibers derived from a fiber source selected from the group consisting of Acacia, Eucalyptus, Maple, Oak, Aspen, Birch, Cottonwood, Alder, Ash, Cherry, Elm, Hickory, Poplar, Gum, Walnut, Locust, Sycamore, Beech, Catalpa, Sassafras, Gmelina, Albizia, Anthocephalus, Magnolia, Bagasse, Flax, Hemp, Kenaf and mixtures thereof. Chemical pulps, however, may be preferred since they impart a superior tactile sense of softness to tissue sheets made therefrom. Pulps derived from both deciduous trees (hereinafter, also referred to as “hardwood”), especially tropical hardwood, and coniferous trees (hereinafter, also referred to as “softwood”) may be utilized. The hardwood and softwood fibers can be blended, or alternatively, can be deposited in layers to provide a stratified web. U.S. Pat. No. 4,300,981 and U.S. Pat. No. 3,994,771 are incorporated herein by reference for the purpose of disclosing layering of hardwood and softwood fibers. Also applicable to the present invention are fibers derived from recycled paper, which may contain any or all of the above categories as well as other non-fibrous materials such as fillers and adhesives used to facilitate the original papermaking.

[0022] In addition to the various wood pulp fibers, other cellulosic fibers such as cotton linters, rayon, and bagasse can be used in this invention. Synthetic fibers, such as polymeric fibers, can also be used. Elastomeric polymers, polypropylene, polyethylene, polyester, polyolefin, and nylon, can be used. The polymeric fibers can be produced by spunbond processes, meltblown processes, and other suitable methods known in the art. One exemplary polyethylene fiber that can be utilized is Pulpex®, available from Hercules, Inc. (Wilmington, Del.).

[0023] An embryonic fibrous web can be typically prepared from an aqueous dispersion of papermaking fibers, though dispersions in liquids other than water can be used. The fibers can be dispersed in the carrier liquid to have a consistency of from about 0.1% to about 0.3%. It is believed that the present invention can also be applicable to moist forming operations where the fibers are dispersed in a carrier liquid to have a consistency less than about 50%, more preferably less than about 10%.

[0024] “Sanitary tissue product” as used herein means a soft, low density (i.e., <about 0.15 g/cm3) web useful as a wiping implement for post-urinary and post-bowel movement cleaning (toilet tissue), for otorhinolaryngolical discharges (facial tissue and/or hankies), and multi-functional absorbent and cleaning uses (absorbent towels).

[0025] “Weight average molecular weight” as used herein means the weight average molecular weight as determined using gel permeation chromatography according to the protocol found in Colloids and Surfaces A. Physico Chemical & Engineering Aspects, Vol. 162, 2000, pg. 107-121.

[0026] “Ply” or “Plies” as used herein means an individual fibrous structure optionally to be disposed in a substantially contiguous, face-to-face relationship with other plies, forming a multiple ply fibrous structure. It is also contemplated that a single fibrous structure can effectively form two “plies” or multiple “plies”, for example, by being folded on itself.

[0027] The fibrous structures and/or sanitary tissue products employing the fibrous structures of the present invention may be characterized as being within a multi-parametric domain defined by empirically determined ranges of one or more and/or two or more and/or three or more of the following parameters: 1) Caliper; 2) Smoothness; 3) Slip and Stick Coefficient; 4) Total Tensile Strength; 5) Flexibility; 6) Bending; 7) Absorbency; 8) Compressional Properties; 9) Basis Weight; 10) Wet Burst Strength; 11) Coefficient of Friction; and/or 12) WABY Factor.

[0028] “Caliper” as used herein means the macroscopic thickness of a sample. Caliper of a sample of fibrous structure and/or sanitary tissue product according to the present invention are obtained on a VIR Electronic Thickness Tester Model II available from Thwing-Albert Instrument Company, Philadelphia, Pa. The caliper measurement can be repeated and recorded at least five (5) times so that an average caliper can be calculated. The result is reported in millimeters.

[0029] “Smoothness” and/or “Physiological Surface Smoothness” as used herein is a factor (hereinafter the PSS Factor and/or SMD Factor) derived from scanning machine-direction fibrous structure and/or sanitary tissue product samples with a profilometer having a diamond stylus, the profilometer being installed in a surface test apparatus such as, for example, is described in the 1991 International paper Physics Conference. TAPPI Book 1, article entitled “Methods for the Measurement of the Mechanical Properties of Tissue Paper” by Ampulski et al. found at page 19, and/or in U.S. Pat. No. 5,059,282 issued to Ampulski et al., both of which are incorporated herein by reference. The smoothness and/or the inverse of smoothness (i.e., roughness) can also be measured using a Kato Surface Tester KES-FB4 which is available from Kato Tekko Co., LTD., Karato-Cho, Nishikiyo, Minami-Ku, Koyota, Japan. Alternatively, the smoothness of a fibrous structure and/or sanitary tissue product according to the present invention may be measured using a Primos Optical Profiler/3D Surface Analyzer commercially available from GF Messtechnik, Berlin, Gennany.

[0030] “Slip-and-Stick Coefficient of Friction” (S&S COF) is defined as the mean deviation of the coefficient of friction. Like the coefficient of friction, it is dimensionless. This test is performed on a KES-FB4 Surface Analyzer from Kato Tekko Co. with a modified friction probe. The probe sled is a two centimeter diameter, 40 to 60 micron glass frit obtained from Ace Glass Company. The normal force of the probe was 12.5 grams. The details of the procedure are described in “Methods for the Measurement of the Mechanical Properties of Tissue Paper” by Ampulski, et. al., 1991 International Paper Physics Conference, page 19, incorporated herein by reference.

[0031] “Total Dry Tensile Strength” or “TDT” of a fibrous structure and/or sanitary tissue product comprising such fibrous structure is measured as follows. One (1) inch by five (5) inch (2.5 cm×12.7 cm) strips of fibrous structure and/or paper product comprising such fibrous structure are provided. The strip is placed on an electronic tensile tester Model 1122 commercially available from Instron Corp., Canton, Mass. in a conditioned room at a temperature of 73° F.±4° F. (about 28° C.±2.2° C.) and a relative humidity of 50%±10%. The crosshead speed of the tensile tester is 2.0 inches per minute (about 5.1 cm/minute) and the gauge length is 4.0 inches (about 10.2 cm). The TDT is the arithmetic total of MD and CD tensile strengths of the strips.

[0032] “Absorbency” and/or “Hydrophilicity” as used herein includes two factors: 1) absorbent capacity and 2) absorbent rate. The absorbent capacity is a measure of the ability of a fibrous structure and/or sanitary tissue product comprising a fibrous structure, while supported horizontally, to hold liquid. The absorbent rate is a measure of the rate at which a fibrous structure and/or sanitary tissue product employing a fibrous structure acquires liquid by wicking. Procedures for measuring absorbency are known in the art. For example, a procedure is described in U.S. Pat. No. 5,908,707.

[0033] “Compressional Properties” as used herein means a set of properties describing the behavior of a fibrous structure and/or sanitary tissue product of the present invention under increasing pressure and the subsequent unloading relief. Nonlimiting examples of compressional properties include bulkiness, richness, energy required for compression and springiness (i.e., resiliency) of the fibrous structure and/or sanitary tissue product. Compressional properties are measurable by a KES-FB3 Compressibility Analyzer commercially available from Kato Tekko Co.

[0034] “Wet Burst Strength” as used herein is a measure of the ability of a fibrous structure and/or a paper product incorporating a fibrous structure to absorb energy, when wet and subjected to deformation normal to the plane of the fibrous structure and/or paper product. Wet burst strength may be measured using a Thwing-Albert Burst Tester Cat. No. 177 equipped with a 2000 gload cell commercially available from Thwing-Albert Instrument Company, Philadelphia, Pa.

[0035] “Basis Weight” as used herein is the weight per unit area of a sample reported in lbs/3000 ft2 or g/m2. Basis weight is measured by preparing one or more samples of a certain area (m2) and weighing the sample(s) of a fibrous structure according to the present invention and/or a paper product comprising such fibrous structure on a top loading balance with a minimum resolution of 0.01 g. The balance is protected from air drafts and other disturbances using a draft shield. Weights are recorded when the readings on the balance become constant. The average weight (g) is calculated and the average area of the samples (m2). The basis weight (g/m2) is calculated by dividing the average weight (g) by the average area of the samples (m2).

[0036] “Machine Direction” or “MD” as used herein means the direction parallel to the flow of the fibrous structure through the papermaking machine and/or product manufacturing equipment.

[0037] “Cross Machine Direction” or “CD” as used herein means the direction perpendicular to the machine direction in the same plane of the fibrous structure and/or paper product comprising the fibrous structure.

[0038] “Apparent Density” or “Density”as used herein means the basis weight of a sample divided by the caliper with appropriate conversions incorporated therein. Apparent density used herein has the units g/cm3.

[0039] “Total Tensile Strength” as used herein means the geometric mean of the machine and cross-machine breaking strengths in grams per cm of sample width. Mathematically, this is the square root of the product of the machine and cross-machine direction breaking strengths in grams per cm of sample width.

[0040] “Bending Property” as used herein is determined for a fibrous structure and/or a sanitary tissue product using the KES-FB2 Pure Bending Tester commercially available from Kato Tekko Co.

[0041] “Flexibility” as used herein means the slope of the secant of the graph-curve derived from force vs. stretch % data which secant passes through the origin (0% stretch, 0 force) and through the point on the graph-curve where the force per centimeter of width is 20 grams. For example, for a fibrous structure and/or sanitary tissue product sample of the present invention which stretches 10% (i.e., 0.1 cm/cm of length) with 20 grams of force per cm of sample width, the slope of the secant through (0% stretch, 0 force) and (10% stretch, 20 force) is 2.0 using the formula:

Slope = \frac{Y^{2} - Y^{1}}{X^{2} - X^{1}}

[0042] “Total Flexibility” as used herein means the geometric mean of the machine-direction flexibility and cross-machine-direction flexibility. Mathematically, this is the square root of the product of the machine-direction flexibility and cross-machine-direction flexibility in grams per cm.

[0043] “WABY Factor” as used herein means the ratio of Total Flexibility to Total Tensile Strength. The WABY Factor has been determined to be a factor which characterizes embodiments of the invention as being strong yet having high bulk softness. This ratio is hereby dubbed the WABY Factor. For instance, a sample having a Total Flexibility of 20 g/cm, and a Total Tensile Strength of 154 g/cm has a WABY Factor of 0.13.

[0044] Briefly, tactile perceivable softness of tissue paper is inversely related to its WABY Factor. Also, note that the WABY Factor is dimensionless because both Flexibility and Total Tensile Strength as defined above are in g/cm, their ratio is dimensionless.

[0045] “Lint” as used herein is measured in accordance with the procedure set forth in commonly assigned U.S. Pat. No. 5,814,188 issued Sep. 29, 1998 to Vinson et al., and incorporated herein by reference.

[0046] As used herein, the articles “a” and “an” when used herein, for example, “an anionic surfactant” or “a fiber” is understood to mean one or more of the material that is claimed or described.

[0047] All percentages and ratios are calculated by weight unless otherwise indicated. All percentages and ratios are calculated based on the total composition unless otherwise indicated.

[0048] Unless otherwise noted, all component or composition levels are in reference to the active level of that component or composition, and are exclusive of impurities, for example, residual solvents or by-products, which may be present in commercially available sources.

Fibrous Structure

[0049] The fibrous structures and/or tissue paper of the present invention can be made by different methods. Nonlimiting examples of fibrous structure types and/or tissue paper types include conventionally pressed and/or felt-pressed tissue paper; pattern densified tissue paper either with a patterned forming wire and/or a patterned fabric/resin belt; high-bulk, uncompacted tissue paper and creped or uncreped tissue paper. The tissue paper may be of a homogenous and/or single layered or multilayered construction; and tissue paper products made therefrom may be of a single-ply or multi-ply construction.

[0050] Further, the fibrous structures of the present invention and/or sanitary tissue products incorporating the same may be creped or uncreped.

[0051] Further yet, the sanitary tissue products incorporating the fibrous structures of the present invention may incorporate dry fibers via an air laid process and/or latex binding agents via a wet laid process.

[0052] Conventional converting methods may be used to convert dried rolls of fibrous structure according to the present invention into one-ply and/or multi-ply sanitary tissue products. Nonlimiting examples of such converting methods include embossing including high pressure embossing, dry creping, ply bonding, calendaring and/or other mechanical treatments to the fibrous structures.

[0053] The fibrous structure may be made with a fibrous furnish that produces a single layer embryonic fibrous web or a fibrous furnish that produces a multi-layer embryonic fibrous web.

[0054] The fibrous structures of the present invention and/or sanitary tissue products comprising such fibrous structures may have a basis weight of from about 12 g/m2 to about 120 g/m2 and/or from about 14 g/m2 to about 80 g/m2 and/or from about 17 g/m2 to about 70 g/m2 and/or from about 20 g/m2 to about 60 g/m2. Typically, a single ply of the fibrous structure has a basis weight of from about 12 g/m2 to about 50 g/m2.

[0055] The fibrous structures of the present invention and/or sanitary tissue products comprising such fibrous structures may have a total dry tensile of greater than about 39 g/cm and/or greater than about 59 g/cm and/or from about 63 g/cm to about 1575 g/cm and/or from about 78 g/cm to about 985 g/cm and/or from about 78 g/cm to about 394 g/cm and/or from about 98 g/cm to about 335 g/cm. Typically a single ply of the fibrous structure has a total dry tensile of from about 39 g/cm to about 590 g/cm.

[0056] The fibrous structures of the present invention and/or sanitary tissue products comprising such fibrous structures may have a wet burst strength of greater than about 10 g/cm and/or from about 12 g/cm to about 394 g/cm and/or from about 13 g/cm to about 197 g/cm and/or from about 15 g/cm to about 197 g/cm and/or from about 15 g/cm to about 78 g/cm.

[0057] The fibrous structures of the present invention and/or sanitary tissue products comprising such fibrous structures may have a slip-and-stick coefficient of friction of greater than about 0.007 and/or from about 0.007 to about 0.055 and/or from about 0.008 to about 0.050 and/or from about 0.008 to about 0.035.

[0058] The fibrous structures of the present invention and/or sanitary tissue products comprising such fibrous structures may have a coefficient of friction of greater than about 0.1 and/or from about 0.1 to about 0.65 and/or from about 0.15 to about 0.60.

[0059] The fibrous structures of the present invention and/or sanitary tissue products comprising such fibrous structures may have a bending of greater than about 0.008 gf*cm2/cm and/or from about 0.008 gf*cm2/cm to about 0.15 gf*cm2/cm and/or from about 0.01 gf*cm2/cm to about 0.14 gf*cm2/cm.

[0060] The fibrous structures of the present invention and/or sanitary tissue products comprising such fibrous structures may have a bulkiness (initial—final thickness) of greater than about 0.03 mm and/or from about 0.03 mm to about 0.5 mm and/or from about 0.05 mm to about 0.4 mm.

[0061] The fibrous structures of the present invention and/or sanitary tissue products comprising such fibrous structures may have a richness (linearity of the compression curve) of greater than about 0.5 and/or from about 0.5 to about 1 and/or from about 0.55 to about 0.85.

[0062] The fibrous structures of the present invention and/or sanitary tissue products comprising such fibrous structures may have an energy required for compression of greater than about 0.02 gf*cm/cm2 and/or from about 0.02 gf*cm/cm2 to about 0.13 gf*cm/cm2 and/or from about 0.025 gf*cm/cm2 to about 0.12 gf*cm/cm2.

[0063] The fibrous structures of the present invention and/or sanitary tissue products comprising such fibrous structures may have a springiness (% resilience) of greater than about 35% and/or from about 35% to about 75% and/or from about 40% to about 65%.

[0064] The fibrous structures of the present invention and/or sanitary tissue products comprising such fibrous structures may have a smoothness as measured using a profilometer (PSS) of greater than about 500 and/or from about 500 to about 1200 and/or from about 600 to about 1000 and/or from about 650 to about 850. Alternatively, the fibrous structures of the present invention and/or sanitary tissue products comprising such fibrous structures may have a smoothness as measured using Kato Surface Tester KES-FB4 (SMD) of greater than about 0.5 microns and/or from about 0.5 microns to about 5 microns and/or from about 0.6 microns to about 5 microns and/or from about 0.7 microns to about 4 microns.

[0065] The fibrous structures of the present invention and/or sanitary tissue products comprising such fibrous structures may have a caliper (4-plies) of greater than about 0.02 cm and/or from about 0.02 cm to about 0.15 cm and/or from about 0.0254 cm to about 0.114 cm.

[0066] The properties described herein may be for a single ply of the fibrous structure and/or a single ply sanitary tissue product and/or for a multi-ply sanitary tissue product that incorporates at least one ply comprising the fibrous structure of the present invention.

Fiber Furnish

[0067] The fiber furnish of the present invention comprises one or more fibers and typically one or more optional ingredients.

Cationic Silicone Polymer

[0068] The cationic silicone polymer of the present invention comprises one or more polysiloxane units, preferably polydimethylsiloxane units of formula —{(CH3)2SiO}c— having a degree of polymerization, c, of from 1 to 1000, preferably of from 20 to 500, more preferably of from 50 to 300, most preferably from 100 to 200, and organosilicone-free units comprising at least one diquaternary unit. In a preferred embodiment of the present invention, the selected cationic silicone polymer has from 0.05 to 1.0 mole fraction, more preferably from 0.2 to 0.95 mole fraction, most preferably 0.5 to 0.9 mole fraction of the organosilicone-free units selected from cationic divalent organic moieties. The cationic divalent organic moiety is preferably selected from N,N,N′,N′-tetramethyl-1,6-hexanediammonium units.

[0069] The selected cationic silicone polymer can also contain from 0 to 0.95 mole fraction, preferably from 0.001 to 0.5 mole fraction, more preferably from 0.05 to 0.2 mole fraction of the total of organosilicone-free units, polyalkyleneoxide amines of the following formula:

[—Y—O(—CaH2aO)b—Y—]

[0070] wherein Y is a divalent organic group comprising a secondary or tertiary amine, preferably a C1 to C8 alkylenamine residue; a is from 2 to 4, and b is from 0 to 100. The polyalkyleneoxide blocks may be made up of ethylene oxide (a=2), propylene oxide (a=3), butylene oxide (a=4) and mixtures thereof, in a random or block fashion.

[0071] Such polyalkyleneoxide amine—containing units can be obtained by introducing in the silicone polymer structure, compounds such as those sold under the tradename Jeffamine® from Huntsman Corporation. A preferred Jeffamine is Jeffamine ED-2003.

[0072] The selected cationic silicone polymer can also contain from 0, preferably from 0.001 to 0.2 mole fraction, of the total of organosilicone-free units, of —NR3+ wherein R is alkyl, hydroxyalkyl or phenyl. These units can be thought of as end-caps.

[0073] Moreover the selected cationic silicone polymer generally contains Ianions, selected from inorganic and organic anions, more preferably selected from saturated and unsaturated C1-C20 carboxylates and mixtures thereof, to balance the charge of the quaternary moieties, thus the cationic silicone polymer also comprises such anions in a quaternary charge-balancing proportion.

[0074] Conceptually, the selected cationic silicone polymers herein can helpfully be thought of as non-crosslinked or “linear” block copolymers including non-fabric-substantive but surface energy modifying “loops” made up of the polysiloxane units, and fabric-substantive “hooks”. One preferred class of the selected cationic polymers (illustrated by Structure 1 hereinafter) can be thought of as comprising a single loop and two hooks; another, very highly preferred, comprises two or more, preferably three or more “loops” and two or more, preferably three or more “hooks” (illustrated by Structures 2a and 2b hereinafter), and yet another (illustrated by Structure 3 hereinafter) comprises two “loops” pendant from a single “hook”.

[0075] Of particular interest in the present selection of cationic silicone polymers is that the “hooks” contain no silicone and that each “hook” comprises at least two quaternary nitrogen atoms.

[0076] Also of interest in the present selection of preferred cationic silicone polymers is that the quaternary nitrogen is preferentially located in the “backbone” of the “linear” polymer, in contradistinction from alternate and less preferred structures in which the quaternary nitrogen is incorporated into a moiety or moieties which form a “pendant” or “dangling” structure off the “backbone”.

[0077] The structures are completed by terminal moieties which can be noncharged or charged. Moreover a certain proportion of nonquaternary silicone-free moieties can be present, for example the moiety [—Y—O(—CaH2aO)b—Y—] as described hereinabove.

[0078] Of course the conceptual model presented is not intended to be limiting of other moieties, for example connector moieties, which can be present in the selected cationic silicone polymers provided that they do not substantially disrupt the intended function as tissue benefit agents.

[0079] In more detail, the cationic silicone polymers herein have one or more polysiloxane units and one or more quaternary nitrogen moieties, including polymers wherein the cationic silicone polymer has the formula:

[0080] wherein:

[0081] R1 is independently selected from the group consisting of: C1-22 alkyl, C2-22 alkenyl, C6-22 alkylaryl, aryl, cycloalkyl, and mixtures thereof;

[0082] R2 is independently selected from the group consisting of: divalent organic moieties that may contain one or more oxygen atoms (such moieties preferably consist essentially of C and H or of C, H and O);

[0083] X is independently selected from the group consisting of ring-opened epoxides;

[0084] R3 is independently selected from polyether groups having the formula:

—M1(CaH2aO)b—M2

[0085] wherein M1 is a divalent hydrocarbon residue; M2 is independently selected from the group consisting of H, C1-22 alkyl, C2-22 alkenyl, C6-22 alkylaryl, aryl, cycloalkyl, C1-22 hydroxyalkyl, polyalkyleneoxide, (poly)alkoxy alkyl, and mixtures thereof;

[0086] Z is independently selected from the group consisting of monovalent organic moieties comprising at least one quaternized nitrogen atom;

[0087] a is from 2 to 4; b is from 0 to 100; c is from 1 to 1000, preferably greater than 20, more preferably greater than 50, preferably less than 500, more preferably less than 300, most preferably from 100 to 200;

[0088] d is from 0 to 100; n is the number of positive charges associated with the cationic silicone polymer, which is greater than or equal to 2; and A is a monovalent anion.

[0089] In a preferred embodiment of the Structure 1 cationic silicone polymers, Z is independently selected from the group consisting of:

[0090] (v) monovalent aromatic or aliphatic heterocyclic group, substituted or unsubstituted, containing at least one quaternized nitrogen atom;

[0091] wherein:

[0092] R12, R13, R14 are the same or different, and are selected from the group consisting of: C1-22 alkyl, C2-22 alkenyl, C6-22 alkylaryl, aryl, cycloalkyl, C1-22 hydroxyalkyl, polyalkyleneoxide, (poly)alkoxy alkyl, and mixtures thereof,

[0093] R15 is —O— or NR19;

[0094] R16 is a divalent hydrocarbon residue;

[0095] R17, R18, R19 are the same or different, and are selected from the group consisting of: H, C1-22 alkyl, C2-22 alkenyl, C6-22 alkylaryl, aryl, cycloalkyl, C1-22 hydroxyalkyl, polyalkyleneoxide, (poly)alkoxy alkyl, and mixtures thereof, and e is from 1 to 6.

[0096] In a highly preferred embodiment, the cationic silicone polymers herein have one or more polysiloxane units and one or more quaternary nitrogen moieties, including polymers wherein the cationic silicone polymer has the formula: (Structure 2a)

[0097] STRUCTURE 2a: Cationic silicone polymer composed of alternating units of:

[0098] (i) a polysiloxane of the following formula

[0099] and

[0100] (ii) a divalent organic moiety comprising at least two quaternized nitrogen atoms.

[0101] Note that Structure 2a comprises the alternating combination of both the polysiloxane of the depicted formula and the divalent organic moiety, and that the divalent organic moiety is organosilicone-free corresponding to a preferred “hook” in the above description.

[0102] In this preferred cationic silicone polymer, R1 is independently selected from the group consisting of: C1-22 alkyl, C2-22 alkenyl, C6-22 alkylaryl, aryl, cycloalkyl, and mixtures thereof;

[0103] R2 is independently selected from the group consisting of: divalent organic moieties that may contain one or more oxygen atoms; X is independently selected from the group consisting of ring-opened epoxides; R3 is independently selected from polyether groups having the formula:

—M1(CaH2aO)b—M2

[0104] wherein M1 is a divalent hydrocarbon residue; M2 is independently selected from the group consisting of H, C1-22 alkyl, C2-22 alkenyl, C6-22 alkylaryl, aryl, cycloalkyl, C1-22 hydroxyalkyl polyalkyleneoxide, (poly)alkoxy alkyl, and mixtures thereof; a is from 2 to 4; b is from 0 to 100; c is from 1 to 1000, preferably greater than 20, more preferably greater than 50, preferably less than 500, more preferably less than 300, most preferably from 100 to 200; and d is from 0 to 100.

[0105] In an even more highly preferred embodiment of the Structure 2a cationic silicone polymer, the cationic silicone polymer has the formula Structure 2b wherein the polysiloxane (i) of the formula described above in Structure 2a is present with (ii) a cationic divalent organic moiety is selected from the group consisting of:

[0106] (d) a divalent aromatic or aliphatic heterocyclic group, substituted or unsubstituted, containing at least one quaternized nitrogent atom; and

[0107] (iii) optionally, a polyalkyleneoxide amine of formula:

[—Y—O(—CaH2aO)b—Y—]

[0108] Y is a divalent organic group comprising a secondary or tertiary amine, preferably a C1 to C8 alkylenamine residue; a is from 2 to 4; b is from 0 to 100; the polyalkyleneoxide blocks may be made up of ethylene oxide (a=2), propylene oxide (a=3), butylene oxide (a=4) and mixtures thereof, in a random or block fashion; and

[0109] (iv) optionally, a cationic monovalent organic moiety, to be used as an end-group, selected from the group consisting of:

[0110] (v) monovalent aromatic or aliphatic heterocyclic group, substituted or unsubstituted, containing at least one quaternized nitrogen atom;

[0111] wherein:

[0112] R4, R5, R6, R7, R8, R9, R10, R11 are the same or different, and are selected from the group consisting of: C1-22 alkyl, C2-22 alkenyl, C622 alkylaryl, aryl, cycloalkyl, C1-22 hydroxyalkyl, polyalkyleneoxide, (poly)alkoxy alkyl, and mixtures thereof; or in which R4 and R6, or R5 and R7, or R8 and R10, or R9 and R11 may be components of a bridging alkylene group;

[0113] R12, R13, R14 are the same or different, and are selected from the group consisting of: C1-22 alkyl, C2-22 alkenyl, C6-22 alkylaryl, C1-22 hydroxyalkyl, polyalkyleneoxide, (poly)alkoxy alkyl groups, and mixtures thereof; and

[0114] R‥is —O— or NR19;

[0115] R16 and M1 are the same or different divalent hydrocarbon residues;

[0116] R17, R18, R19 are the same or different, and are selected from the group consisting of: H, C1-22 alkyl, C2-22 alkenyl, C6-22 alkylaryl, aryl, cycloalkyl, C1-22 hydroxyalkyl, polyalkyleneoxide, (poly)alkoxy alkyl, and mixtures thereof; and

[0117] Z1 and Z2 are the same or different divalent hydrocarbon groups with at least 2 carbon atoms, optionally containing a hydroxy group, and which may be interrupted by one or several ether, ester or amide groups;

[0118] wherein, expressed as fractions on the total moles of the organosilicone—free moieties, the cationic divalent organic moiety (ii) is preferably present at of from 0.05 to 1.0 mole fraction, more preferably of from 0.2 to 0.95 mole fraction, and most preferably of from 0.5 to 0.9 mole fraction; the polyalkyleneoxide amine (iii) can be present of from 0.0 to 0.95 mole fraction, preferably of from 0.001 to 0.5, and more preferably of from 0.01 to 0.2 mole fraction; if present, the cationic monovalent organic moiety (iv) is present of from 0 to 0.2 mole fraction, preferably of from 0.001 to 0.2 mole fraction;

[0119] e is from 1 to 6; m is the number of positive charges associated with the cationic divalent organic moiety, which is greater than or equal to 2; and A is an anion.

[0120] Note that Structure 2b comprises the alternating combination of both the polysiloxane of the depicted formula and the divalent organic moiety, and that the divalent organic moiety is organosilicone-free corresponding to a preferred “hook” in the above general description. Structure 2b moreover includes embodiments in which the optional polyalkyleneoxy and/or end group moieties are either present or absent.

[0121] In yet another embodiment, the cationic silicone polymers herein have one or more polysiloxane units and one or more quaternary nitrogen moieties, and including polymers wherein the cationic silicone polymer has the formula: (Structure 3)

[0122] wherein:

[0123] R1 is independently selected from the group consisting of: C1-22 alkyl, C2-22 alkenyl, C6-22 alkylaryl, aryl, cycloalkyl, and mixtures thereof,

[0124] R2 is independently selected from the group consisting of: divalent organic moieties that may contain one or more oxygen atoms;

[0125] X is independently selected from the group consisting of ring-opened epoxides;

[0126] R3 is independently selected from polyether groups having the formula:

—M1(CaH2aO)b—M2

[0127] wherein M1 is a divalent hydrocarbon residue; M2 is independently selected from the group consisting of H, C1-22 alkyl, C2-22 alkenyl, C6-22 alkylaryl, aryl, cycloalkyl, C1-22 hydroxyalkyl polyalkyleneoxide, (poly)alkoxy alkyl, and mixtures thereof;

[0128] X is independently selected from the group consisting of ring-opened epoxides;

[0129] W is independently selected from the group consisting of divalent organic moieties comprising at least one quaternized nitrogen atom;

[0130] a is from 2 to 4; b is from 0 to 100; c is from 1 to 1000, preferably greater than 20, more preferably greater than 50, preferably less than 506, more preferably less than 300, most preferably from 100 to 200; d is from 0 to 100; n is the number of positive charges associated with the cationic silicone polymer, which is greater than or equal to 1; and A is a monovalent anion, in other words, a suitable counterion.

[0131] In preferred cationic silicone polymers of Structure 3, W is selected from the group consisting of:

[0132] (d) a divalent aromatic or aliphatic heterocyclic group, substituted or unsubstituted, containing at least one quaternized nitrogent atom; and

[0133] wherein

[0134] R4, R5, R6, R7, R8, R9, R10, R11 are the same or different, and are selected from the group consisting of: C1-22 alkyl, C2-22 alkenyl, C6-22 alkylaryl, aryl, cycloalkyl, C1-22 hydroxyalkyl, polyalkyleneoxide, (poly)alkoxy alkyl, and mixtures thereof; or in which R4 and R6, or R5 and R7, or R8 and R10, or R9 and R11 may be components of a bridging alkylene group; and

[0135] Z1 and Z2 are the same or different divalent hydrocarbon groups with at least 2 carbon atoms, optionally containing a hydroxy group, and which may be interrupted by one or several ether, ester or amide groups.

[0136] The cationic silicone polymer may be applied to the embryonic fibrous web and/or applied to a dried fibrous structure and/or before and/or concurrently and/or after converting one or more dried fibrous structures into a sanitary tissue product. Nonlimiting examples of suitable processes for applying the cationic silicone polymer to the fibrous structure include spraying, including but not limited to using a spraying disk, onto the embryonic fibrous web and/or dried fibrous structure before it is wound into a roll of paper, extruding, especially via slot extrusion, onto the embryonic web and/or dried fibrous structure, and/or by printing, especially gravure printing, onto the embryonic fibrous web and/or dried fibrous structure and/or sanitary tissue product.

[0137] The cationic silicone polymer may be applied to the embryonic fibrous web and/or dried fibrous structure and/or sanitary tissue product in a homogeneous and/or patterned and/or inhomogeneous fashion.

[0138] The cationic silicone polymer can be applied to the embryonic fibrous web and/or fibrous structure and/or sanitary tissue product of the present invention as it is being made on a papermaking machine or thereafter: either while it is wet (i.e., prior to final drying) or dry (i.e., after final drying).

[0139] In one embodiment, an aqueous mixture containing the cationic silicone polymer is sprayed onto the embryonic fibrous web and/or fibrous structure and/or sanitary tissue product as it courses through the papermaking machine: for example, and not by way of limitation, referring to a papermaking machine of the general configuration disclosed in U.S. Pat. No. 3,301,746, either before the predryer, or after the predryer, or even after the Yankee dryer/creping station although the fibrous structure is preferably creped after the cationic silicone polymer is applied.

[0140] The cationic silicone polymer can be applied to the embryonic fibrous web in an aqueous solution, emulsion, or suspension. The cationic silicone polymer can also be applied in a solution containing a suitable, nonaqueous solvent, in which the cationic silicone polymer dissolves or with which the cationic silicone polymer is miscible: for example, hexane. The cationic silicone polymer may be supplied in neat form or, preferably, emulsified with a suitable surfactant emulsifier. The cationic silicone polymer can be applied after embryonic fibrous web formation has been effected. In a typical process, the embryonic fibrous web is formed and then dewatered prior to cationic silicone polymer application in order to reduce the loss of cationic silicone polymer due to drainage of free water. The cationic silicone polymer can be applied to the wet embryonic fibrous web at a fiber consistency of greater than about 15% in the manufacture of conventionally pressed tissue paper; and to a wet embryonic fibrous web having a fiber consistency of between about 20% and about 35% in the manufacture of tissue paper in papermaking machines wherein the newly formed embryonic fibrous web is transferred from a fine mesh Fourdrinier to a relatively coarse imprinting/carrier fabric and/or belt.

[0141] Methods of applying the cationic silicone polymer to the embryonic fibrous web and/or dried fibrous structure and/or sanitary tissue product include spraying, slot extrusion and gravure printing. Other methods include deposition of the cationic silicone polymer onto a forming wire or fabric or belt which is then contacted by the embryonic fibrous web and/or dried fibrous structure and/or sanitary tissue product. Equipment suitable for spraying cationic silicone polymer-containing liquids onto embryonic fibrous webs and/or dried fibrous structures and/or sanitary tissue products include external mix, air atomizing nozzles such as the 2 mm nozzle available from V.I.B. Systems, Inc., Tucker, Ga. Equipment suitable for printing cationic silicone polymer-containing liquids onto embryonic fibrous webs and/or dried fibrous structures and/or sanitary tissue products includes rotogravure printers.

[0142] The cationic silicone polymer can be applied uniformly to the embryonic fibrous web and/or dried fibrous structure and/or sanitary tissue product. A uniform distribution is desirable so that substantially the entire sheet benefits from the tactile effect of the cationic silicone polymer. Continuous and patterned distributions are both within the scope of the invention and meet the above criteria.

[0143] Application methods described herein for the cationic silicone polymer can be used with dry or wet embryonic fibrous webs and/or fibrous structures and/or sanitary tissue products.

[0144] Exemplary art related to the addition of silicone materials to the fibrous structure during its formation includes U.S. Pat. No. 5,059,282 issued to Ampulski, et. al. on Oct. 22, 1991 incorporated herein by reference. The Ampulski patent discloses a process for adding a polysiloxane compound to a wet tissue web (“fibrous structure”) (preferably at a fiber consistency between about 20% and about 35%). Such a method represents an advance in some respects over the addition of chemicals into the slurry vats supplying the papermaking machine. For example, such means target the application to one of the web surfaces as opposed to distributing the additive onto all of the fibers of the furnish.

[0145] Considerable art has been devised to apply silicones and/or other chemical softeners to already-dried paper webs (“fibrous structures”) either at the so-called dry end of the papermaking machine or in a separate converting operation subsequent to the papermaking step. Exemplary art from this field includes U.S. Pat. No. 5,215,626 issued to Ampulski, et. al. on Jun. 1, 1993; U.S. Pat. No. 5,246,545 issued to Ampulski, et. al. on Sep. 21, 1993; and U.S. Pat. No. 5,525,345 issued to Warner, et. al. on Jun. 11, 1996, all incorporated herein by reference. The U.S. Pat. No. 5,215,626 discloses a method for preparing soft tissue paper by applying a polysiloxane to a dry web (“fibrous structure”). The U.S. Pat. No.5,246,545 Patent discloses a similar method utilizing a heated transfer surface. Finally, the Warner Patent discloses methods of application including roll coating and extrusion for applying particular compositions to the surface of a dry tissue web (“fibrous structure”).

[0146] The cationic silicone may be applied to one or both surfaces of an embryonic web and/or dried fibrous structure and/or sanitary tissue product such that one or both external surfaces of a resulting sanitary tissue product incorporating the fibrous structure has the cationic silicone polymer present thereon.

[0147] In one embodiment, the cationic silicone may be applied to one surface of an embryonic web and/or dried fibrous structure and/or sanitary tissue product such that the cationic silicone passes through the embryonic web and/or dried fibrous structure and/or sanitary tissue product such that both surfaces of an embryonic web and/or fibrous structure and/or sanitary tissue product have cationic silicone present thereon.

[0148] The fibrous structure of the present invention and/or sanitary tissue product incorporating such fibrous structure may comprise from about 0.0001% to about 10% and/or from about 0.001% to about 5% and/or from about 0.005% to about 3% and/or from about 0.005% to about 2% and/or from about 0.005% to about 1.5% by dry weight of the fibrous structure or sanitary tissue product of the cationic silicone polymer.

[0149] Reference is made to the following patents and patent applications which do also disclose cationic silicone polymers suitable for use in the present invention: WO 02/06 403; WO 02/18528, EP 1 199 350; DE OS 100 36 533; WO 00/24853; WO 02/10259; WO 02/10257 and WO 02/10256.

[0150] Synthesis Example—When not otherwise known or available in commerce, the cationic silicone polymers herein can be prepared by conventional techniques as disclosed in WO 02/18528.

Optional Ingredients

[0151] The fibrous structures of the present invention may, in addition to the cationic silicone polymer, comprise an optional ingredient selected from the group consisting of permanent wet strength resins, chemical softeners other than the cationic silicones described hereinabove, temporary wet strength resins, dry strength resins, wetting agents, lint resisting agents, absorbency-enhancing agents, immobilizing agents, especially in combination with emollient lotion compositions, antiviral agents including organic acids, antibacterial agents, polyol polyesters, antimigration agents, polyhydroxy plasticizers, fillers (clays), humectants and mixtures thereof. Such optional ingredients may be added to the fiber furnish, the embryonic fibrous web and/or the dried fibrous structure. Such optional ingredients may be present in the fibrous structure at any level based on the dry weight of the fibrous structure.

[0152] The optional ingredients may be applied to the fiber furnish and/or the embryonic fibrous web and/or the dried fibrous structure and/or the sanitary tissue product of the present invention. Further, the optional ingredients, such as other chemical softeners, more particularly, lotions, especially, transferable lotions may be applied to the dried fibrous structure and/or sanitary tissue product after the cationic silicone has been applied thereto.

[0153] The optional ingredients may be present in the fibrous structure and/or sanitary tissue product of the present invention at a level of from about 0.001% to about 50% and/or from about 0.001% to about 30% and/or from about 0.001% to about 22% and/or from about 0.01% to about 5% and/or from about 0.03% to about 3% and/or from about 0.05 to about 2% and/or from about 0.1% to about 1% by weight, on a dry fibrous structure or sanitary tissue product basis.

Processes of the Present Invention

[0154] The fibrous structure of the present invention may be made by any suitable papermaking process.

[0155] A nonlimiting example of a suitable papermaking process for making the fibrous structure of the present invention is described as follows.

[0156] In one embodiment, a fiber furnish is prepared by mixing one or more fibers with water. One or more additional optional ingredients may be added to the fiber furnish. The fiber furnish may then be put into a headbox, which may be a layered headbox, of a papermaking machine. The fiber furnish may then be deposited on a foraminous surface to form a single layer or a multi-layer embryonic fibrous web. The cationic silicone polymer and/or optional ingredients may be added to the embryonic fibrous web by spraying and/or extruding and/or printing and/or by any other suitable process known to those of ordinary skill in the art. The embryonic web may then be transferred to a through-air drying belt and/or a Yankee dryer such that the embryonic fibrous web is dried via through-air drying and/or via the Yankee dryer. From the through-air drying belt, if there is one present, the fibrous structure may be transferred to a Yankee dryer. From the Yankee dryer, the fibrous structure may be transferred to a rewinder to form a roll of dried fibrous structure. During this transfer step, the cationic silicone polymer and/or optional ingredients may be applied to the dried fibrous structure. The fibrous structure may be converted into various paper products, particularly sanitary tissue products, both in single-ply forms and/or in multi-ply forms. During the converting step, the cationic silicone polymer may be applied to the fibrous structure. Accordingly, the cationic silicone polymer may be applied before and/or concurrently with and/or after the converting step.

Nonlimiting Examples

[0157] The following examples employ a cationic silicone polymer in accordance with the present invention. The cationic silicone polymer is used typically in the form of an emulsion containing an amine oxide, a nonionic surfactant, ethanol and water. In one embodiment, the emulsion is formed as follows: 24.39 g of cationic silicone solution (80% cationic silicone polymer/20% ethanol) is mixed with 6.05 g C12-15 EO3 (4) with a normal laboratory blade mixer. After 10 minutes, 6.7g of ethanol is added. After another 10 minutes, 8.71 g of C12-14 alkyl dimethyl amineoxide 31% active solution in water (2) is added. After another 10 minutes, 54.2 g of demineralized water are quickly added to the mixture, under continuous stirring. The pH of the emulsion is brought to pH 7.5 with 0.8 g 0.1M HCl. The emulsion can be diluted to about 10-20% cationic silicone polymer concentration. Example 1—An embodiment of a facial tissue in accordance with the present invention is prepared as follows.

[0158] An aqueous slurry of Northern Softwood Kraft (NSK) of about 3% consistency is made up using a conventional pulper and is passed through a stock pipe toward the headbox of the Fourdrinier. A 1% dispersion of Hercules' Kymene 557. LX is prepared and is added to the NSK stock pipe at a rate sufficient to deliver about 0.8% Kymene 557 LX based on the dry weight of the ultimate sanitary tissue paper. The absorption of the permanent wet strength resin is enhanced by passing the treated slurry through an in-line mixer. An aqueous solution of Carboxymethyl cellulose (CMC) dissolved in water and diluted to a solution strength of 1% is added next to the NSK stock pipe after the in-line mixer at a rate of about 0.1% CMC by weight based on the dry weight of the ultimate sanitary tissue paper. The aqueous slurry of NSK fibers passes through a centrifugal stock pump to aid in distributing the CMC. An aqueous dispersion of DiTallow DiMethyl Ammonium Methyl Sulfate (DTDMAMS) (170° F./76.6° C.) at a concentration of 1% by weight is added to the NSK stock pipe at a rate of about 0.1% by weight DTDMAMS based on the dry weight of the ultimate sanitary tissue paper.

[0159] An aqueous slurry of eucalyptus bleached kraft fibrous pulp fibers (from Aracruz—Brazil) of about 1.5% by weight is made up using a conventional repulper and is passed through a stock pipe toward the headbox of the Fourdrinier. This Eucalyptus furnish joins the NSK slurry at the fan pump where both are diluted with white water to about 0.2% consistency.

[0160] An aqueous slurry of eucalyptus bleached kraft fibrous pulp fibers (from Aracruz—Brazil) of about 3% by weight is made up using a conventional repulper. The Eucalyptus slurry passes to the second fan pump where it is diluted with white water to a consistency of about 0.2%.

[0161] The slurries of NSK/eucalyptus and eucalyptus are directed into a multi-channeled headbox suitably equipped with layering leaves to maintain the streams as separate layers until discharged onto a traveling Fourdrinier wire. A three-chambered headbox is used. The eucalyptus slurry containing 48% of the dry weight of the ultimate sanitary tissue paper is directed to the chamber leading to the layer in contact with the wire, while the NSK/eucalyptus slurry comprising 52% (27-35% NSK and 17-25% eucalyptus) of the dry weight of the ultimate paper is directed to the chamber leading to the center and inside layer. The NSK/eucalyptus and eucalyptus slurries are combined at the discharge of the headbox into a composite slurry.

[0162] The composite slurry is discharged onto the traveling Fourdrinier wire and is dewatered assisted by a deflector and vacuum boxes.

[0163] The embryonic wet web is transferred from the Fourdrinier wire, at a fiber consistency of about 17% by weight at the point of transfer, to a patterned drying fabric. The drying fabric is designed to yield a pattern-densified tissue with discontinuous low-density deflected areas arranged within a continuous network of high density (knuckle) areas. This drying fabric is formed by casting an impervious resin surface onto a fiber mesh supporting fabric. The supporting fabric is a 48×52 filament, dual layer mesh. The thickness of the resin cast is about 8 mil above the supporting fabric. The knuckle area is about 35-50% and the open cells remain at a frequency of about 10-87 per cm2.

[0164] Further de-watering is accomplished by vacuum assisted drainage until the web has a fiber consistency of about 23-27%.

[0165] While remaining in contact with the patterned forming fabric, the patterned web is pre-dried by air blown through to a fiber consistency of about 60% by weight.

[0166] The semi-dry web is then adhered to the surface of a Yankee dryer with a sprayed creping adhesive comprising a 0.250% aqueous solution of polyvinyl alcohol. The creping adhesive is delivered to the Yankee surface at a rate of 0.1% adhesive solids based on the dry weight of the web. The fiber consistency is increased to about 98% before the web is dry creped from the Yankee with a doctor blade. After the doctor blade, the web is calendared across all its width with a steel to rubber calendar roll operating at a loading of 2-3.5 MPa.

[0167] The resulting tissue has a basis weight of about 20-25 g/m2; a 1-ply total dry tensile between 98 and 146 g/cm, a 1-ply wet burst between 13 and 26 gr/cm and a 2-ply caliper of about 0.038-0.05 cm. The resulting tissue is then combined with a like sheet to form a two-ply, creped, pattern-densified tissue so that the eucalyptus fibers face the outside and it is subjected to calendaring between two smooth steel calendar rolls. The cationic silicone polymer emulsion is then slot extruded onto both sides in contact with a human's skin, at an add-on amount of approximately 0.8-1.0 g/m2 of emulsion per side, equivalent to a total add-on level of 0.7-1.0% by weight of silicone per ply, based on the total weight of fibers. Product is then ply-bonded using a mechanical plybond wheel to ensure that both plies stay together. The resulting two-ply tissue has a) a total basis weight of about 39-50 g/m2; b) a 2-ply total dry tensile between 177 and 276 gr/cm; c) a 2-ply wet burst between 39 and 51 gr/cm; d) a 4-ply caliper of about 0.05 and 0.09 cm; e) a slip-stick coefficient of friction of about 0.010-0.013; f) a Bending Stiffness (B) of about 0.01-0.04 g.cm2/cm; and g) a lint of about 10-12 lint units.

[0168] The resultant tissue paper is judged softer than an untreated tissue sample by a panel of expert judges. Example 2—An embodiment of a facial tissue in accordance with the present invention is prepared according to Example 1, with the Eucalyptus fibers being replaced with Acacia fibers (from PT Tel—Indonesia). Example 3—An embodiment of a wet pressed, dry creped conventional tissue handkerchief in accordance with the present invention is prepared as follows.

[0169] The paper web has a composition of about 40% Northern Softwood Kraft and 60% Eucalyptus has a basis weight of approximately 15.4 g/m2, a 4-ply caliper of about 0.36 mm, a total dry tensile strength of about 768 g/cm and a wet burst of about 225 g. It contains about 0.9% by weight of the dry fibers of a wet strength resin (Kymene 617™, available from Hercules Incorporated of Wilmington, Del., USA), 0.14% by weight of the dry fibers of dry strength resin (carboxymethyl cellulose, available from available from Hercules Incorporated of Wilmington, Del., USA) and approximately 0.05% by weight of the dry fibers of a wet end softener (di-hard tallow diethylester dimethyl ammonium chloride).

[0170] Following the wet pressed, dry creped conventional papermaking of the paper web, four sheets of paper web are combined together in an off line combining operation. The pre-combined 4-ply parent roll is subsequently converted into a 4-ply tissue product. The 4-ply parent roll is unwound and subjected to calendaring between two smooth steel calendar rolls followed by high pressure embossing to achieve ply bonding. The majority of the tissue paper remains unembossed.

[0171] The cationic silicone polymer emulsion is then printed onto the surface of the 4-ply tissue web using a roto-gravure printing process. About 1.5 g/m2 of the emulsion is transferred to each side of the 4-ply product, equivalent to a total add-on of silicone of 0.5% by weight of the tissue weight.

[0172] The printing station consists of two engraved anilox rolls facing each other in a horizontal arrangement and forming a gap in between through which the 4-ply tissue web is run. The geometry is arranged in a way that the rolls touch the paper web and transfer lotion macroscopically uniformly onto both surfaces of the 4-ply paper web but the web does not wrap any of the two anilox rolls. The anilox rolls are engraved to a cell volume of about 3 ml per square meter, and supplied with lotion from a closed supply chamber designed to fill the engraved volume with lotion. The gap between the two rolls is adjusted to achieve the target add-on level

[0173] The tissue is cut into sheets of approximately 21 cm×21cm and folded.

[0174] The 4-ply paper tissue product obtained by the above described process has a basis weight of approximately 61 g/m2, a thickness of 0.27 mm, an MD strength of 504 g/cm, a CD strength of 240 g/cm, a wet burst of about 200 g. It contains about 0.5% by weight of the tissue weight of the cationic silicone polymer.

[0175] The resulting tissue paper is judged softer than an untreated tissue sample by a panel of expert judges. Example 4—An embodiment of a tissue handkerchief in accordance with the present invention is made according to Example 3 except that 1.5 g/m2 of the cationic silicone polymer emulsion is printed onto each outer side of the tissue, equivalent to a total add on level of 1% by weight of the tissue weight of the cationic silicone polymer. The 4-ply paper tissue product has a basis weight of approximately 62 g/m2, a thickness of 0.27 mm, a MD strength of 469 g/cm, a CD strength of 220 g/cm, and a wet burst of about 200 g.

[0176] The resulting tissue paper is judged softer than the tissue sample treated with 0.5% by weight of the tissue by a panel of expert judges. Example 5—An embodiment of a sanitary tissue product in accordance with the present invention is made according to Example 3 except that the emulsion of the cationic silicone is applied to the web using a different application process.

[0177] The emulsified softener is sprayed on to the tissue using a rotary disk spraying equipment (commercially available from Weitmann & Konrad GmbH & Co KG, Leinfelden, Germany). The equipment is equipped with 5 rotors per applicator, designed to cover a web width of 448 mm. Each rotor consists of two disks stacked on top of each other. Each of the disks is fed with equal amounts of the cationic silicone emulsion. The distance of the center of the rotor to the web is about 154 mm. The disks have a diameter of approximately 80 mm and are operated at a speed of about 3600 rpm. The disks are evenly spaced out at a distance of 11.2 cm to cover a total width of 448 mm. Under the effect of centrifugal forces generated by the spinning rotors the liquid is dispersed into droplets. 72°, equal to 20%, of the spray generated around the disks is deposited onto the web while the rest is recovered and fed back to the applicator through a re-circulation line. The spray of each rotor covers about 224 mm of the web except for the first and the last rotor which covers only about 11.2cm of the web. At any position the spray pattern of two rotors are overlapping.

[0178] The emulsion add on is adjusted to approximately 1.5 g/m2 on each side.

[0179] The resulting 4-ply tissue product has a basis weight of approximately 61 g/m2 and contains approximately 0.5% by weight of the tissue weight of the cationic silicone polymer.

[0180] The resulting tissue paper is judged softer than an untreated tissue sample by a panel of expert judges.

[0181] All documents cited in the Detailed Description of the Invention are, in relevant part, incorporated herein by reference; the citation of any document is not to be considered as an admission that it is prior art with respect to the present invention.

[0182] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Cationic silicone polymer-containing fibrous structures

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