FIBROUS STRUCTURES EXHIBITING IMPROVED WET COMPRESSION PROPERTIES AND METHODS FOR MAKING SAME

Abstract

Fibrous structures that exhibit improved wet compression properties, and more particularly to wet compression-enhancing agent-containing fibrous structures that provide superior wet compression properties compared to the same fibrous structures without the wet compression-enhancing agent, are provided.

Description

FIELD OF THE INVENTION

The present invention relates to fibrous structures that exhibit improved wet compression properties, and more particularly to wet compression-enhancing agent-containing fibrous structures that provide superior wet compression properties compared to the same fibrous structures without the wet compression-enhancing agent.

BACKGROUND OF THE INVENTION

Fibrous structures comprising polymers such as polyacrylamide and/or polyacrylamide containing polymers and such as absorbent gel materials, for example crosslinked acrylic acid particles, are known in the art.

In light of the foregoing, it is clear that there has existed a long felt, unmet need for a fibrous structure, more particularly a dry fibrous structure that exhibits superior wet compression properties compared to the same fibrous structure without the wet compression-enhancing agent.

Accordingly, there is a need for a fibrous structure comprising a wet compression-enhancing agent such that the fibrous structure exhibits superior wet compression properties compared to the same fibrous structure without the wet compression-enhancing agent.

SUMMARY OF THE INVENTION

The present invention fulfills the needs described above by providing a fibrous structure, for example a dry paper towel that exhibits superior wet compression properties compared to the same fibrous structure without the wet compression-enhancing agent.

In one example of the present invention, a fibrous structure comprising a wet compression-enhancing agent such that the fibrous structure exhibits at least one of the following properties:

a. at least one Wet Compression value in a load value range of from 100 g to 300 g during the Compression Portion of the Wet Compression Test Method that is statistically greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent as measured according to the Wet Compression Test Method; and

b. at least one Wet Compression value in a load value range of from 50 g to 300 g during the Relaxation Portion of the Wet Compression Test Method that is statistically greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent as measured according to the Wet Compression Test Method.

Accordingly, the present invention provides wet compression-enhancing agent containing fibrous structures that exhibit superior wet compression properties compared to known fibrous structures void of such wet compression-enhancing agent(s) and methods for making such fibrous structures.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

“Fibrous structure” as used herein means a structure that comprises one or more fibrous filaments and/or fibers. In one example, a fibrous structure according to the present invention means an orderly arrangement of filaments and/or fibers within a structure in order to perform a function. Non-limiting examples of fibrous structures of the present invention include paper, fabrics (including woven, knitted, and non-woven), and absorbent pads (for example for diapers or feminine hygiene products).

Non-limiting examples of processes for making fibrous structures include known wet-laid processes, such as wet-laid papermaking processes, and air-laid processes, such as air-laid papermaking processes. Wet-laid and/or air-laid papermaking processes and/or air-laid papermaking processes typically include a step of preparing a composition comprising a plurality of fibers that are suspended in a medium, either wet, more specifically aqueous medium, or dry, more specifically gaseous medium, such as air. The aqueous medium used for wet-laid processes is oftentimes referred to as a fiber slurry. The fiber composition is then used to deposit a plurality of fibers onto a forming wire or belt such that an embryonic fibrous structure is formed, after which drying and/or bonding the fibers together results in a fibrous structure. Further processing the fibrous structure may be carried out such that a finished fibrous structure is formed. For example, in typical papermaking processes, the finished fibrous structure is the fibrous structure that is wound on the reel at the end of papermaking, and may subsequently be converted into a finished product, e.g. a sanitary tissue product.

Another process that can be used to produce the fibrous structures is a melt-blowing and/or spunbonding process where a polymer composition is spun into filaments and collected on a belt to produce a fibrous structure. In one example, a plurality of fibers may be mixed with the filaments prior to collecting on the belt and/or a plurality of fibers may be deposited on a prior produced fibrous structure comprising filaments.

The fibrous structures of the present invention may be homogeneous or may be layered in the direction normal to the machine direction. If layered, the fibrous structures may comprise at least two and/or at least three and/or at least four and/or at least five layers.

The fibrous structures of the present invention may be co-formed fibrous structures. “Co-formed” as used herein means that the fibrous structure comprises a mixture of at least two different components wherein at least one of the components comprises a filament, such as a polypropylene filament, and at least one other component, different from the first component, comprises a solid additive, such as a fiber and/or a particulate. In one example, a co-formed fibrous structure comprises solid additives, such as fibers, such as wood pulp fibers and/or absorbent gel articles of manufacture and/or filler particles and/or particulate spot bonding powders and/or clays, and filaments, such as polypropylene filaments.

“Solid additive” as used herein means a fiber and/or a particulate.

“Particulate” as used herein means a granular substance or powder.

“Fiber” and/or “Filament” 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. In one example, a “fiber” is an elongate particulate as described above that exhibits a length of less than 5.08 cm (2 in.) and a “filament” is an elongate particulate as described above that exhibits a length of greater than or equal to 5.08 cm (2 in.).

Fibers are typically considered discontinuous in nature. Non-limiting examples of fibers include wood pulp fibers and synthetic staple fibers such as polyester fibers.

Filaments are typically considered continuous or substantially continuous in nature. Filaments are relatively longer than fibers. Non-limiting examples of filaments include meltblown and/or spunbond filaments. Non-limiting examples of articles of manufacture that can be spun into filaments include natural polymers, such as starch, starch derivatives, cellulose and cellulose derivatives, hemicellulose, hemicellulose derivatives, and synthetic polymers including, but not limited to polyvinyl alcohol filaments and/or polyvinyl alcohol derivative filaments, and thermoplastic polymer filaments, such as polyesters, nylons, polyolefins such as polypropylene filaments, polyethylene filaments, and biodegradable or compostable thermoplastic fibers such as polylactic acid filaments, polyhydroxyalkanoate filaments and polycaprolactone filaments. The filaments may be monocomponent or multicomponent, such as bicomponent filaments.

In one example of the present invention, “fiber” refers to papermaking fibers. 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, sulfite, and sulfate pulps, as well as mechanical pulps including, for example, groundwood, thermomechanical pulp and chemically modified thermomechanical pulp. 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”) 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. 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 articles of manufacture such as fillers and adhesives used to facilitate the original papermaking.

In addition to the various wood pulp fibers, other cellulosic fibers such as cotton linters, rayon, lyocell and bagasse can be used in this invention. Other sources of cellulose in the form of fibers or capable of being spun into fibers include grasses and grain sources.

“Dry fibrous structure” as used herein means a fibrous structure that comprises less than 30% and/or less than 20% and/or less than 15% and/or less than 10% and/or less than 7% and/or less than 5% and/or less than 3% and/or less than 2% and/or less than 1% and/or less than 0.5% by weight of moisture based on the fibrous structure as measured according to the Moisture Content Test Method described herein.

“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 otorhinolaryngological discharges (facial tissue), multi-functional absorbent and cleaning uses (absorbent towels), and folded sanitary tissue products such as napkins and/or facial tissues including folded sanitary tissue products dispensed from a container, such as a box. The sanitary tissue product may be convolutedly wound upon itself about a core or without a core to form a sanitary tissue product roll.

In one example, the sanitary tissue product of the present invention comprises a fibrous structure according to the present invention.

The sanitary tissue products of the present invention may exhibit a basis weight between about 10 g/m² to about 120 g/m² and/or from about 15 g/m² to about 110 g/m² and/or from about 20 g/m² to about 100 g/m² and/or from about 30 to 90 g/m². In addition, the sanitary tissue product of the present invention may exhibit a basis weight between about 40 g/m² to about 120 g/m² and/or from about 50 g/m² to about 110 g/m² and/or from about 55 g/m² to about 105 g/m² and/or from about 60 to 100 g/m².

The sanitary tissue products of the present invention may exhibit a total dry tensile strength of at least 59 g/cm (150 g/in) and/or from about 78 g/cm (200 g/in) to about 394 g/cm (1000 g/in) and/or from about 98 g/cm (250 g/in) to about 335 g/cm (850 g/in). In addition, the sanitary tissue product of the present invention may exhibit a total dry tensile strength of at least 196 g/cm (500 g/in) and/or from about 196 g/cm (500 g/in) to about 394 g/cm (1000 g/in) and/or from about 216 g/cm (550 g/in) to about 335 g/cm (850 g/in) and/or from about 236 g/cm (600 g/in) to about 315 g/cm (800 g/in). In one example, the sanitary tissue product exhibits a total dry tensile strength of less than about 394 g/cm (1000 g/in) and/or less than about 335 g/cm (850 g/in). In another example, the sanitary tissue products of the present invention may exhibit a total dry tensile strength of at least 196 g/cm (500 g/in) and/or at least 236 g/cm (600 g/in) and/or at least 276 g/cm (700 g/in) and/or at least 315 g/cm (800 g/in) and/or at least 354 g/cm (900 g/in) and/or at least 394 g/cm (1000 g/in) and/or from about 315 g/cm (800 g/in) to about 1968 g/cm (5000 g/in) and/or from about 354 g/cm (900 g/in) to about 1181 g/cm (3000 g/in) and/or from about 354 g/cm (900 g/in) to about 984 g/cm (2500 g/in) and/or from about 394 g/cm (1000 g/in) to about 787 g/cm (2000 g/in).

The sanitary tissue products of the present invention may exhibit an initial total wet tensile strength of at least 118 g/cm (300 g/in) and/or at least 157 g/cm (400 g/in) and/or at least 196 g/cm (500 g/in) and/or at least 236 g/cm (600 g/in) and/or at least 276 g/cm (700 g/in) and/or at least 315 g/cm (800 g/in) and/or at least 354 g/cm (900 g/in) and/or at least 394 g/cm (1000 g/in) and/or from about 118 g/cm (300 g/in) to about 1968 g/cm (5000 g/in) and/or from about 157 g/cm (400 g/in) to about 1181 g/cm (3000 g/in) and/or from about 196 g/cm (500 g/in) to about 984 g/cm (2500 g/in) and/or from about 196 g/cm (500 g/in) to about 787 g/cm (2000 g/in) and/or from about 196 g/cm (500 g/in) to about 591 g/cm (1500 g/in).

In another example, the sanitary tissue products of the present invention may exhibit an initial total wet tensile strength of less than about 78 g/cm (200 g/in) and/or less than about 59 g/cm (150 g/in) and/or less than about 39 g/cm (100 g/in) and/or less than about 29 g/cm (75 g/in).

The sanitary tissue products of the present invention may exhibit a density (measured at 95 g/in²) of less than about 0.60 g/cm³ and/or less than about 0.30 g/cm³ and/or less than about 0.20 g/cm³ and/or less than about 0.10 g/cm³ and/or less than about 0.07 g/cm³ and/or less than about 0.05 g/cm³ and/or from about 0.01 g/cm³ to about 0.20 g/cm³ and/or from about 0.02 g/cm³ to about 0.10 g/cm³.

The sanitary tissue products of the present invention may be in the form of sanitary tissue product rolls. Such sanitary tissue product rolls may comprise a plurality of connected, but perforated sheets of fibrous structure, that are separably dispensable from adjacent sheets. In one example, one or more ends of the roll of sanitary tissue product may comprise an adhesive and/or dry strength agent to mitigate the loss of fibers, especially wood pulp fibers from the ends of the roll of sanitary tissue product.

The sanitary tissue products of the present invention may comprises additives such as softening agents, temporary wet strength agents, permanent wet strength agents, bulk softening agents, lotions, silicones, wetting agents, latexes, especially surface-pattern-applied latexes, dry strength agents such as carboxymethylcellulose and starch, and other types of additives suitable for inclusion in and/or on sanitary tissue products.

“Weight average molecular weight” as used herein means the weight average molecular weight M_w (in units of g/mol) 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.

“Number average molecular weight” as used herein means the number average molecular weight M_n (in units of g/mol) 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.

“Basis Weight” as used herein is the weight per unit area of a sample reported in lbs/3000 ft² or g/m² and is measured according to the Basis Weight Test Method described herein.

“By weight of moisture” or “moisture content” means the amount of moisture present in a fibrous structure measured according to the Moisture Content Test Method described herein immediately after the fibrous structure has been conditioned in a conditioned room at a temperature of 73° F.±4° F. (about 23° C.±2.2° C.) and a relative humidity of 50%±10% for 2 hours.

“Machine Direction” or “MD” as used herein means the direction parallel to the flow of The fibrous structure through The fibrous structure making machine and/or sanitary tissue product manufacturing equipment.

“Cross Machine Direction” or “CD” as used herein means the direction parallel to the width of The fibrous structure making machine and/or sanitary tissue product manufacturing equipment and perpendicular to the machine direction.

“Ply” as used herein means an individual, integral fibrous structure.

“Plies” as used herein means two or more individual, integral fibrous structures disposed in a substantially contiguous, face-to-face relationship with one another, forming a multi-ply fibrous structure and/or multi-ply sanitary tissue product. It is also contemplated that an individual, integral fibrous structure can effectively form a multi-ply fibrous structure, for example, by being folded on itself.

“Water-soluble material” as used herein means a material that is miscible in water. In other words, a material that is capable of forming a stable (does not separate for greater than 5 minutes after forming the homogeneous solution) homogeneous solution with water at ambient conditions.

“Retained” as used herein with respect to a wet compression-enhancing agent being retained by a fibrous structure means that the wet compression-enhancing agent does not become disassociated from a fibrous structure comprising the wet compression-enhancing agent under normal use conditions. In one example, the wet compression-enhancing agent does not become disassociated from a fibrous structure comprising the wet compression-enhancing agent containing the wet compression-enhancing agent under normal use conditions after the fibrous structure is saturated with distilled water.

Fibrous Structure

A non-limiting example of a fibrous structure of the present invention may be a dry fibrous structure, such as a dry paper towel.

In one example, the fibrous structure comprises two or more wet compression-enhancing agents. In another example, the fibrous structure comprises a blend (mixture) of two or more wet compression-enhancing agents. In another example, the two or more wet compression-enhancing agents are different wet compression-enhancing agents.

In one example, the fibrous structure comprises a web. In another example, the fibrous structure comprises a particle.

The fibrous structure of the present invention may comprise a plurality of pulp fibers. Further, the fibrous structure of the present invention may comprise a single-ply or multi-ply sanitary tissue product, such as a paper towel.

The fibrous structure of the present invention may comprise a wet compression-enhancing agent. When present, the wet compression-enhancing agent(s) may be present in and/or on the fibrous structure at a level of greater than 0.005% and/or greater than 0.01% and/or greater than 0.05% and/or greater than 0.1% and/or greater than 0.15% and/or greater than 0.2% and/or less than 5% and/or less than 3% and/or less than 2% and/or less than 1% by weight of the fibrous structure. In one example, the wet compression-enhancing agent is present in and/or on the fibrous structure at a level of from about 0.005% to about 1% by weight of the fibrous structure.

In another example of the present invention, a fibrous structure may comprise a wet compression-enhancing agent at a level of from greater than 0 pounds/ton (#/ton) and/or greater than 0.1#/ton and/or greater than 0.5#/ton and/or greater than 1#/ton and/or greater than 2#/ton and/or greater than 3 #/ton and/or to less than 20 #/ton and/or to less than 15 #/ton and/or to less than 10 #/ton and/or to less than 6 #/ton and/or to 5 #/ton or less and/or to 4 #/ton or less by weight of the fibrous structure. The level of wet compression-enhancing agent present in and/or on a fibrous structure as used herein according to the present invention is in terms of active solids basis of the wet compression-enhancing agent.

The fibrous structure may comprise other ingredients in addition to the wet compression-enhancing agent, for example a surfactant. The surfactant may be present in the fibrous structure at a level of from about 0.01% to about 0.5% by weight of the fibrous structure. Non-limiting examples of a suitable surfactant include C_8-16 alkyl polyglucoside, cocoamido propyl sulfobetaine or mixtures thereof.

In another example, the wet compression-enhancing agent may be present in and/or on a fibrous structure in a pattern, such as a non-random repeating pattern composing lines and or letters/words, and/or present in and/or on regions of different density, different basis weight, different elevation and/or different texture of the fibrous structure. In one example, the wet compression-enhancing agent may be present in and/or on a fibrous structure in a pattern such that is it phased registered with embossments on the fibrous structure, perforations in the fibrous structure, wet molded texture in the fibrous structure, and/or printing on the fibrous structure.

In another example, the fibrous structure of the present invention exhibits at least one Wet Compression value in a load value range of from 100 g to 300 g during the Compression Portion of the Wet Compression Test Method that is statistically greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent as measured according to the Wet Compression Test Method. In another example, the fibrous structure of the present invention exhibits at least one Wet Compression value in the load value range of from 100 g to 300 g during the Compression Portion of the Wet Compression Test Method that is greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent by at least 0.010 mm as measured according to the Wet Compression Test Method. In still another example, the fibrous structure of the present invention exhibits at least one Wet Compression value in the load value range of from 100 g to 300 g during the Compression Portion of the Wet Compression Test Method that is greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent by at least 0.012 mm as measured according to the Wet Compression Test Method. In even another example, the fibrous structure of the present invention exhibits at least one Wet Compression value in the load value range of from 100 g to 300 g during the Compression Portion of the Wet Compression Test Method that is greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent by at least 0.014 mm as measured according to the Wet Compression Test Method described herein.

In another example, the fibrous structure of the present invention exhibits a Wet Compression value of greater than 0.446 mm at a load value of 300 g during the Compression Portion of the Wet Compression Test Method and/or a Wet Compression value of greater than 0.543 mm at a load value of 200 g during the Compression Portion of the Wet Compression Test Method and/or a Wet Compression value of greater than 0.622 mm at a load value of 150 g during the Compression Portion of the Wet Compression Test Method and/or a Wet Compression value of greater than 0.676 mm at a load value of 125 g during the Compression Portion of the Wet Compression Test Method and/or a Wet Compression value of greater than 0.742 mm at a load value of 100 g during the Compression Portion of the Wet Compression Test Method and/or a Wet Compression value of greater than 0.824 mm at a load value of 75 g during the Compression Portion of the Wet Compression Test Method and/or a Wet Compression value of greater than 0.923 mm at a load value of 50 g during the Compression Portion of the Wet Compression Test Method as measured according to the Wet Compression Test Method described herein.

In yet another example of the present invention, a fibrous structure of the present invention exhibits at least one Wet Compression value in a load value range of from 50 g to 300 g during the Relaxation Portion of the Wet Compression Test Method that is statistically greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent as measured according to the Wet Compression Test Method. In another example, a fibrous structure of the present invention exhibits at least one Wet Compression value in a load value range of from 50 g to 300 g during the Relaxation Portion of the Wet Compression Test Method that is greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent as measured according to the Wet Compression Test Method. In even another example of the present invention, a fibrous structure exhibits at least one Wet Compression value in the load value range of from 50 g to 300 g during the Relaxation Portion of the Wet Compression Test Method that is greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent by at least 0.010 mm as measured according to the Wet Compression Test Method described herein.

In still another example of the present invention, a fibrous structure of the present invention exhibits at least one Wet Compression value in the load value range of from 50 g to 300 g during the Relaxation Portion of the Wet Compression Test Method that is greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent by at least 0.012 mm as measured according to the Wet Compression Test Method. In another example, a fibrous structure exhibits at least one Wet Compression value in the load value range of from 50 g to 300 g during the Relaxation Portion of the Wet Compression Test Method that is greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent by at least 0.014 mm as measured according to the Wet Compression Test Method described herein.

In one example, a fibrous structure of the present invention exhibits a Wet Compression value of greater than 0.444 mm at a load value of 300 g during the Relaxation Portion of the Wet Compression Test Method and/or a Wet Compression value of greater than 0.452 mm at a load value of 200 g during the Relaxation Portion of the Wet Compression Test Method and/or a Wet Compression value of greater than 0.463 mm at a load value of 150 g during the Relaxation Portion of the Wet Compression Test Method and/or a Wet Compression value of greater than 0.471 mm at a load value of 125 g during the Relaxation Portion of the Wet Compression Test Method and/or a Wet Compression value of greater than 0.484 mm at a load value of 100 g during the Relaxation Portion of the Wet Compression Test Method and/or a Wet Compression value of greater than 0.503 mm at a load value of 75 g during the Relaxation Portion of the Wet Compression Test Method and/or a Wet Compression value of greater than 0.536 mm at a load value of 50 g during the Relaxation Portion of the Wet Compression Test Method as measured according to the Wet Compression Test Method described herein.

In one example, the fibrous structure of the present invention comprises a multi-ply fibrous structure, for example a two-ply fibrous structure, wherein the wet compression-enhancing agent is contained on/in one or both plies.

Wet Compression-Enhancing Agents

The wet compression-enhancing agents of the present invention may be any suitable material, such as a polymer, for example a water-soluble polymer, that when applied to and/or present within a fibrous structure provides the fibrous structure at least one of the following properties:

a. at least one Wet Compression value in a load value range of from 100 g to 300 g during the Compression Portion of the Wet Compression Test Method that is statistically greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent as measured according to the Wet Compression Test Method described herein; and

b. at least one Wet Compression value in a load value range of from 50 g to 300 g during the Relaxation Portion of the Wet Compression Test Method that is statistically greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent as measured according to the Wet Compression Test Method described herein. In one example the fibrous structure exhibits both (a) and (b) properties described above.

The wet compression-enhancing agents do not include permanent and/or temporary wet strength agents that form amidol and/or hemiacetal bonds with each other and/or with pulp fibers within a fibrous structure, such as polyamide-epichlorohydrin crosslinking agents, for example Kymene® and polyacrylamide-based crosslinking agents, for example Hercobond® both commercially available from Ashland Inc. In other words, the scope of the present invention explicitly excludes materials that increase the wet tensile strength of a fibrous structure by crosslinking with each other and/or with pulp fibers within a fibrous structure.

The wet compression-enhancing agents of the present invention may be homopolymers, such as homopolymer of the acrylamide monomer (i.e., polyacrylamide), and/or a copolymer or terpolymer or other polymer derived from four or more monomers. In one example, the wet compression-enhancing agent comprises a homopolymer of acrylamide monomers; namely, polyacrylamide.

In one example, the charge and charge density of the wet compression-enhancing agent may be altered/adjusted by including charged monomers, such as anionically charged monomers and/or cationically charged monomers. For example, an anionic polyacrylamide may be prepared by copolymerization of acrylamide monomers and anionic acrylic acid monomers with charge density impacted by the ratio of monomers utilized. Anionic formulas utilize AE (anionic emulsion) or AD (anionic dewatered emulsion) nomenclature. Whereas cationic polyacrylamide may be prepared by copolymerization of acrylamide monomers and a cationic ester monomer such as chloromethylated acrylic monomer with charge density impacted by the ratio of monomers utilized. Cationic formulas utilize CE (cationic emulsion) or CD (cationic dewatered emulsion) nomenclature. In addition, amphoteric polyacrylamide may be prepared by copolymeration of acrylamide monomers, anionic acrylic acid monomers and a cationic ester monomer.

In one example, the wet compression-enhancing agent comprises an anionic polyacrylamide having a weight average molecular weight of from about 7,000,000 g/mol to about 30,000,000 g/mol.

In another example, the wet compression-enhancing agent comprises a cationic polyacrylamide having a weight average molecular weight of from about 2,000,000 g/mol to about 12,000,000 g/mol.

In one example, the wet compression-enhancing agent exhibits a weight average molecular weight of greater than 750,000 and/or greater than 1,500,000 and/or greater than 4,000,000 and/or to about 40,000,000 and/or to about 20,000,000 and/or to about 10,000,000 g/mol.

In another example, the wet compression-enhancing agent exhibits a number average molecular weight of greater than 200,000 g/mol and/or greater than 500,000 g/mol and/or greater than 750,000 g/mol and/or greater than 900,000 g/mol to less than 2,000,000 g/mol and/or less than 1,750,000 g/mol and/or less than 1,500,000 g/mol. In one example, the wet compression-enhancing agent exhibits a number average molecular weight of from about 500,000 g/mol to about 2,000,000 g/mol and/or from about 900,000 g/mol to about 1,700,000 g/mol.

In one example, the wet compression-enhancing agent of the present invention exhibits an average particle size distribution of less than 5000 d·nm and/or less than 3000 d·nm and/or less than 2000 d·nm and/or greater than 10 d·nm and/or greater than 100 d·nm and/or greater than 500 d·nm and/or greater than 1000 d·nm.

In one example, the wet compression-enhancing agent comprises a polymer comprising monomeric units derived from acrylic acid and/or quaternary ammonium compounds and/or acrylamide. In one example, polyethyleneimines, such as Lupasol®, which is commercially available from BASF Corporation, are not suitable as wet compression-enhancing agents within the present invention.

In one example, the wet compression-enhancing agent comprises a flocculating agent as compared to a coagulating agent.

A flocculating agent is a chemical that results in colloids and other suspended particles, especially in liquids, to aggregate. An example of a flocculating agent according to the present invention is Rhodia's Mirapol®.

A coagulating agent on the other hand, for purposes of the present invention is a chemical that results in a liquid changing into a thickened solid. An example of a coagulating agent according to the present invention is BASF Corporation's Lupasol®.

In one example, the wet compression-enhancing agent comprises a homopolymer of polyacrylamide, such as Hyperfloc®, which is commercially available from Hychem, Inc. The wet compression-enhancing agent may comprise an anionic polyacrylamide, a nonionic polyacrylamide and/or a cationic polyacrylamide. In one example, the wet compression-enhancing agent comprises a cationic polyacrylamide.

In one example, the wet compression-enhancing agent may be used as a highly concentrated inverse emulsion (for example a water-in-oil emulsion), containing greater than 10% and/or greater than 15% and/or greater than 20% and/or greater than 25% and/or greater than 30% and/or greater than 35% and/or to about 60% and/or to about 55% and/or to about 50% and/or to about 45% active. The oil phase may consist of high quality mineral oil with boiling point range of 468-529° F. or a heavy mineral oil with boiling point range of 608-968° F. In another example the wet compression-enhancing agents may be used as a highly concentrated dewatered emulsion for example dry particles suspended in a continuous oil phase, containing greater than 10% and/or greater than 15% and/or greater than 20% and/or greater than 25% and/or greater than 30% and/or greater than 35% and/or to about 60% and/or to about 55% and/or to about 50% and/or to about 45% active. The oil phase may consist of high quality mineral oil with boiling point range of 468-529° F. or a heavy mineral oil with boiling point range of 608-968° F. In one example, the oil phase of the dewatered emulsion comprises a hydrocarbon fluid, such as white mineral oil, that exhibits a VOC content of less than 60% as measured according to the VOC Test Method and an emulsifying surfactant and/or inverting surfactant. In addition, the soil adsorbing agent of the dewatered emulsion may exhibit a net charge density of greater than −5 meq/g to less than 5 meq/g and/or from greater than −5 to about −0.1 meq/g as measured according to the Charge Density Test Method, described herein. In still another example, the soil adsorbing agent may exhibit a UL Viscosity of from about 1 to about 6 cP as measured according to the UL Viscosity Test Method described herein.

In one example, the wet compression-enhancing agent may be used as a highly concentrated inverse emulsion wherein the continuous phase of the inverse emulsion comprises mineral oil, such as white mineral oil.

In still another example, the wet compression-enhancing agent may be used as a dewatered inverse emulsion, such as Hyperfloc® ND823, AD589, and CD864, which are commercially available from SNF Floerger and/or Hychem, Inc., which consist of micron size particles of highly coiled polymer in a continuous oil phase.

The inverse emulsions of the present invention may be directly applied to a surface of a fibrous structure, such as a surface of a dry fibrous structure, a surface of a wet fibrous structure and/or added to the wet-end of a papermaking process.

In one example, the wet compression-enhancing agent comprises a blend of two or more wet compression-enhancing agents. In one example, the wet compression-enhancing agent comprises a blend of a polyacrylamide water-in-oil emulsion (such as Hyperfloc® NE823F) and a polyacrylamide dewatered inverse emulsion (such as Hyperfloc® ND823). In one example, the blend comprises 50% by volume or greater and/or 60% or greater by volume and/or 75% or greater by volume and/or 80% by volume or greater.

In one example of the present invention, the soil adsorbing agent present in the article of manufacture exhibits a volatile organic content (VOC) of less than 20% and/or less than 15% and/or less than 10% and/or less than 5% as measured according to the VOC Test Method described herein. In another example, an article of manufacture of the present invention comprises a first soil adsorbing agent that exhibits a Volatile Organic Carbon content (VOC) of greater than 20% and a second soil adsorbing agent that exhibits a Volatile Organic Carbon content (VOC) of less than 20% and/or less than 15% and/or less than 10% and/or less than 5% as measured according to the VOC Test Method described herein.

In another example of the present invention, the soil adsorbing agent present in the article of manufacture exhibits a Total Volatiles content of less than 55% and/or less than and/or less than 50% and/or less than 45% and/or less 40% and/or less than 40% and/or less than 35% and/or less than 25% and/or less than 15% as measured according to the VOC Test Method described herein.

In another example of the present invention, the soil adsorbing agent present in the article of manufacture exhibits a Moisture content of less than 30% and/or less than 25% and/or less than 20% and/or less than 15% as measured according to the VOC Test Method described herein.

Table 1 below illustrates Total Volatiles content, Moisture content, and Volatile Organic Carbon content (as measured according to the VOC Test Method described herein) of examples of wet compression-enhancing agents, in this case nonionic polyacrylamides; namely, Hyperfloc® NE823E, Hyperfloc® NE823F, and Hyperfloc® ND823 (commercially available from SNF Floerger and/or Hychem, Inc.) alone and in blends with each other prepared from commercially available materials.

	TABLE 1
		Total
		Volatiles	Moisture	VOC
	Hyperfloc Material	(%)	(%)	(%)
	NE823E	60.1	37.4	22.7
	NE823F lot RA07/1310	57.3	35.7	21.6
	NE823F lot RA10/1276	57.6	35.0	22.6
	NE823F lot RA10/1216	57.1	36.9	20.2
	NE823F lot RA07/1307	57.2	36.4	20.9
	NE823F lot RA06/1309	56.9	35.4	21.5
	Average NE823F	57.2	35.9	21.4
	Std. Dev.	0.24	0.75	0.87
	ND823 lot DA06/1216	14.04	5.31	8.73
	Calculated
	25/75 Blend of	24.83	12.93	11.90
	NE823F/ND823
	50/50 Blend of	35.62	28.25	15.01
	NE823F/ND823
	75/25 Blend of	46.41	28.25	18.22
	NE823F/ND823
	Measured
	25/75 Blend of	14.2	10.5	3.7
	NE823F/ND823
	50/50 Blend of	29.9	17.6	12.3
	NE823F/ND823
	75/25 Blend of	44.0	23.3	20.7
	NE823F/ND823

Table 2 below illustrates the impact of incorporating a wet compression-enhancing agent, in this case an anionic polyacrylamide wet compression-enhancing agent, into a fibrous structure, a paper towel, such as a wet-laid, through-air dried (TAD), wet microcontracted, 2-ply paper towel. The Wet Compression Values for loads C5 to C75 and R5 to R25 are statistically different.

	TABLE 2
		Control Fibrous	Invention A
		Structure	2-ply Fibrous
		(No wet	Structure
		compression-	NE823F
		enhancing agent)	(1.3 #/ton)
	Load (g)	(mm)	(mm)
	C5	1.208	1.308
	C10	1.139	1.198
	C25	1.025	1.058
	C50	0.905	0.926
	C75	0.810	0.828
	C100	0.733	0.746
	C125	0.670	0.681
	C150	0.619	0.628
	C200	0.543	0.549
	C300	0.451	0.453
	R5	0.697	0.773
	R10	0.657	0.710
	R25	0.586	0.611
	R50	0.531	0.541
	R75	0.503	0.509
	R100	0.486	0.490
	R125	0.475	0.478
	R150	0.467	0.470
	R200	0.457	0.459
	R300	0.449	0.451

Table 3 below illustrates the impact of incorporating a 50/50 mixture (blend) of two wet compression-enhancing agent, in this case an anionic polyacrylamide wet compression-enhancing agent and a nonionic polyacrylamide wet compression-enhancing agent, into a fibrous structure, a paper towel, such as a wet-laid, through-air dried (TAD), wet microcontracted, 2-ply paper towel. The Wet Compression Values for loads C25 to C75 and C300 and R5 to R300 are statistically different.

	TABLE 3
		Control Fibrous	Invention B
		Structure	2-ply Fibrous
		(No wet	Structure
		compression-	50/50 NE823F/ND823
		enhancing agent)	(1.3 #/ton)
	Load (g)	(mm)	(mm)
	C5	1.258	1.287
	C10	1.154	1.179
	C25	1.014	1.037
	C50	0.884	0.906
	C75	0.789	0.808
	C100	0.713	0.729
	C125	0.651	0.666
	C150	0.601	0.614
	C200	0.526	0.539
	C300	0.435	0.446
	R5	0.751	0.766
	R10	0.685	0.701
	R25	0.587	0.601
	R50	0.521	0.533
	R75	0.489	0.502
	R100	0.471	0.483
	R125	0.460	0.471
	R150	0.451	0.463
	R200	0.441	0.452
	R300	0.433	0.444

Table 4 below illustrates the impact of incorporating a wet compression-enhancing agent, in this case a nonionic polyacrylamide wet compression-enhancing agent, into a fibrous structure, a paper towel, such as a wet-laid, through-air dried (TAD), wet microcontracted, 2-ply paper towel. The Wet Compression Values for loads C50 to C300 and R50 to R300 are statistically different.

	TABLE 4
		Control Fibrous
		Structure	Invention C
		(No wet	2-ply Fibrous Structure
		compression-	ND823
		enhancing agent)	(1.3 #/ton)
	Load (g)	(mm)	(mm)
	C5	1.305	1.292
	C10	1.193	1.199
	C25	1.052	1.067
	C50	0.922	0.937
	C75	0.823	0.838
	C100	0.741	0.758
	C125	0.675	0.691
	C150	0.621	0.637
	C200	0.542	0.557
	C300	0.445	0.458
	R5	0.776	0.776
	R10	0.710	0.714
	R25	0.607	0.617
	R50	0.535	0.548
	R75	0.502	0.515
	R100	0.483	0.496
	R125	0.470	0.483
	R150	0.462	0.475
	R200	0.451	0.464
	R300	0.443	0.456

In one example, the wet compression-enhancing agent of the present invention is water-soluble.

In another example, the wet compression-enhancing agent of the present invention comprises a linear polymer. In still another example, the wet compression-enhancing agent comprises a branched polymer. In yet another example, the wet compression-enhancing agent comprises a crosslinked polymer.

Processes for Making Fibrous Structure

The fibrous structure of the present invention may be made by any suitable process known in the art. For example, if the fibrous structure is a web, any suitable web making process can be used.

In one example, the fibrous structure may be made by a process comprising the step of contacting a surface of the fibrous structure with a wet compression-enhancing agent according to the present invention. We have surprisingly found that direct application of the high active content water in oil emulsion to the dry sheet can be accomplished without significantly disrupting the sheet structure and providing for improved VFS absorbent capacity in much the same way as superabsorbent polymers without the negative consumer response associated with release of visible super absorbent gel particles contaminating the surface being cleaned or the consumers hands.

In another example of a process for making a fibrous structure, comprises the steps of:

• • a. providing a fiber slurry;
  • b. depositing the fiber slurry onto a foraminous wire to form an embryonic web;
  • c. drying the embryonic web to produce a fibrous structure; and
  • d. contacting the fibrous structure with a wet compression-enhancing agent to produce a fibrous structure (for example a dry fibrous structure) in accordance with the present invention.

In yet another example of a process for making a fibrous structure, comprises the steps of:

• • a. providing a fiber slurry comprising a wet compression-enhancing agent;
  • b. depositing the fiber slurry onto a foraminous wire to form an embryonic web; and
  • c. drying the embryonic web to produce a fibrous structure (for example a dry fibrous structure) in accordance with the present invention; and
  • d. optionally, contacting the fibrous structure with a wet compression-enhancing agent.

The fiber slurry may comprise permanent and/or temporary wet strength agents such as Kymene® (permanent wet strength) and Hercobond® (temporary wet strength) both available from Ashland Inc.

In still yet another example of a process for making an air-laid fibrous structure comprises the steps of:

• • a. providing pulp fibers;
  • b. producing an air-laid fibrous structure from the pulp fibers; and
  • c. contacting a surface of the air-laid fibrous structure with a wet compression-enhancing agent according to the present invention.

In one example, the wet compression-enhancing agent may be added to a fibrous structure of the present invention during papermaking, between the Yankee dryer and the reel, and/or during converting by applying it to one or more surfaces of the fibrous structure. In one example, a single-ply paper towel comprises the wet compression-enhancing agent on one surface of the paper towel. In another example, a single-ply paper towel comprises the wet compression-enhancing agent on both surfaces of the paper towel. In still another example, a two-ply paper towel comprises the wet compression-enhancing agent on one or both exterior surfaces of the two-ply paper towel. In still another example, a two-ply paper towel comprises the wet compression-enhancing agent on one or more interior surfaces of the two-ply paper towel. In yet another example, a two-ply paper towel comprises the wet compression-enhancing agent on one or more exterior surfaces and one or more interior surfaces of the two-ply paper towel. One of ordinary skill would understand that exterior surfaces and various interior surfaces of a three or more ply paper towel could comprise the wet compression-enhancing agent.

In one example, the fibrous structure may be made by adding a wet compression-enhancing agent into the wet end of a wet laid papermaking process. In other words, the wet compression-enhancing agent may be added to a fiber slurry comprising hardwood and/or softwood fibers prior to depositing the slurry onto a foraminous wire.

In another example, the fibrous structure of the present invention may be made by printing a wet compression-enhancing agent onto a surface of a fibrous structure, for example in a converting operation. The printing operation may occur by any suitable printing equipment, for example by way of a gravure roll.

In still another example, an fibrous structure of the present invention may be made by extruding a wet compression-enhancing agent onto a surface of a fibrous structure during one or more converting operations.

In even another example, a fibrous structure of the present invention may be made by spraying a wet compression-enhancing agent onto a surface of a fibrous structure.

In yet another example, a fibrous structure of the present invention may be made by spraying a wet compression-enhancing agent onto a wet fibrous structure during papermaking after the vacuum dewatering step, but before the predryers and/or after the predryers, but before the Yankee.

In one example, one or more wet compression-enhancing agents may be added to a fibrous structure in the wet-end, in the fibers prior to inclusion into a fiber slurry, and/or during papermaking and/or during converting of the fibrous structure and/or to a finished fibrous structure, such as a paper towel. For example, a first wet compression-enhancing agent may be added to a fibrous structure in the wet-end and second wet compression-enhancing agent, the same or different as the first, may be added to the fibrous structure during papermaking and/or converting.

A wet compression-enhancing agent comprising Hyperfloc® NE823F represents an APE free, non-ionic water-in-oil emulsion (about 30% active-about 30% polyacrylamide, 30% water, 30% high boiling oil, and 10% surfactants) available from Hychem, Inc. under the trade name NE823F. A wet compression-enhancing agent comprising Hyperfloc® ND823 represents a dewatered emulsion consisting of (about 50% active-about 50% polyacrylamide, 40% high boiling oil and 10% surfactants). A blend (mixture) of the Hyperfloc® NE823F and ND823, for example via low shear mixing, result in a stable emulsion with no obvious settling. Formulations ranging from 100% NE823F to 100% ND823 were found to be stable with minimal short duration low shear mixing as is typically recommend with water in oil emulsion products. A 50/50 volume blend is prepared. Other blends such as 25/75 and/or 75/25 by volume of NE823F and ND823 may be utilized. The Hyperfloc® 50/50 volume blend emulsion of NE823F/ND823 is applied directly to an embossed surface of a fibrous structure via an extruder in converting utilizing an S-wrap configuration such that the extruder is positioned below the sheet with full wrap over the extruder head. Alternatively, dual side extrusion may be utilized.

In even yet another example, a fibrous structure of the present invention may be made by depositing a plurality of fibers mixed with a wet compression-enhancing agent in an air-laid and/or coform process.

In still another example, a fibrous structure may be made that contains wet compression-enhancing agents by including the wet compression-enhancing agents at acceptable locations within spunbonding, meltblowing, carding, and/or hydroentangling processes.

The wet compression-enhancing agent may be applied to and/or included in a fibrous structure in a pattern, such as a non-random, repeating pattern. In one example, the wet compression-enhancing agent may be phase registered with embossments in the fibrous structure, wet molded texture in the fibrous structure, perforations in the fibrous structure, and/or printing on the fibrous structure.

Non-Limiting Examples

Example 1

Articles of manufacture, in particular fibrous structures; namely, paper towels are produced utilizing a cellulose furnish consisting of a Northern Softwood Kraft (NSK) and Eucalyptus Hardwood (EUC) at a ratio of approximately 65/35. The NSK is refined as needed to maintain target wet burst at the reel. Any furnish preparation and refining methodology common to the papermaking industry can be utilized.

A 3% active solution Kymene 1142 is added to the refined NSK line prior to an in-line static mixer and 1% active solution of Wickit 1285, an ethoxylated fatty alcohol defoamer available from Ashland Inc. is added to the EUC furnish. The addition levels are 20 and 1 lbs active/ton of paper, respectively.

The NSK and EUC thick stocks are then blended into a single thick stock line followed by addition of 1% active carboxymethylcellulose (CMC) solution at 7 lbs active/ton of paper towel, and optionally, a softening agent may be added.

The thick stock is then diluted with white water at the inlet of a fan pump to a consistency of about 0.15% based on total weight of NSK and EUC fiber. The diluted fiber slurry is directed to a non-layered configuration headbox such that a wet web produced from the fiber slurry is formed onto a Fourdrinier wire (foraminous wire).

Dewatering occurs through the Fourdrinier wire and is assisted by deflector and vacuum boxes. The Fourdrinier wire is of a 5-shed, satin weave configuration having 84 machine-direction and 78 cross-direction monofilaments per inch, respectively. The speed of the Fourdrinier wire is about 675 fpm (feet per minute).

The embryonic wet web is transferred from the Fourdrinier wire at a fiber consistency of about 22% at the point of transfer to a patterned belt through-air-drying resin carrying fabric. To provide fibrous structure products of the present invention, the speed of the patterned through-air-drying fabric is about 18% slower than the speed of the Fourdrinier wire (for example a wet molding process). In another example, the embryonic wet web may be transferred to a patterned belt and/or fabric where the speed of the patterned through-air-drying fabric is approximately the same as the speed of the Fourdrinier wire.

Further de-watering is accomplished by vacuum assisted drainage until the web has a fiber consistency of about 26-28%.

While remaining in contact with the patterned drying fabric, the web is pre-dried by air blow-through pre-dryers to a fiber consistency of about 65% by weight.

After the pre-dryers, the semi-dry web is transferred to a Yankee dryer and adhered to the surface of the Yankee dryer with a sprayed creping adhesive. The creping adhesive is an aqueous dispersion with the actives consisting of about 2#/ton polyvinyl alcohol, and 0.5#/ton of release aid (CREPETROL® R6390). Crepe aids such as CREPETROL® A3025 may also be utilized. CREPETROL® A3025 and CREPETROL® R6390 are commercially available from Ashland Inc. (formerly Hercules Inc.). The creping adhesive is delivered to the Yankee surface at a rate of about 0.15% adhesive solids based on the dry weight of the web. The fiber consistency is increased to about 97% before the web is dry creped from the Yankee with a doctor blade.

The doctor blade has a bevel angle of about 45° and is positioned with respect to the Yankee dryer to provide an impact angle of about 101°. The Yankee dryer is operated at a temperature of about 177° C. and a speed of about 550 fpm. The fibrous structure is wound in a roll using a surface driven reel drum having a surface speed of about 610 fpm. In another example, the doctor blade may have a bevel angle of about 25° and is positioned with respect to the Yankee dryer to provide an impact angle of about 81° and the reel is run about 10% slower than the speed of the Yankee.

A first wet compression-enhancing agent comprising a dewatered (dehydrated) Hyperfloc® emulsion of micron size polymer particles dispersed in oil (about 50% active-about 50% polyacrylamide, 40% high boiling oil, and 10% surfactants) available from Hychem, Inc. under the trade name ND823 is applied directly to a surface of a fibrous structure in the converting operation via an extruder to the embossed side of a two ply product. Additionally, a second extruder can be utilized to apply soil attracting polymer to the un-embossed side of the sheet.

A second wet compression-enhancing agent comprising a Hyperfloc® water-in-oil emulsion (about 30% active-about 30% polyacrylamide, 30% water, 30% high boiling oil, and 10% surfactants) with the active polymer consisting of highly coiled polymer dissolved in micron size water droplets available from Hychem, Inc. under the trade name NE823F, which is the non-dewatered (non-dehyrdated) form of Hyperfloc® ND823, is applied directly to a surface of a fibrous structure via a spray application in papermaking onto the fabric side and/or the wire side of the dry fibrous structure between the calender and the reel. Alternatively extruder application in converting can be utilized.

The fibrous structure may be embossed prior to and/or subsequent to the application of one or both of the wet compression-enhancing agents. It may then be subsequently converted into a two-ply paper towel product having a basis weight of about 28-33 lbs/3000 ft² with fabric side out and/or wire side out.

Example 2

Articles of manufacture, in particular fibrous structures; namely, paper towels are produced utilizing a cellulose furnish consisting of a Northern Softwood Kraft (NSK) and Eucalyptus Hardwood (EUC) at a ratio of approximately 70/30. The NSK is refined as needed to maintain target wet burst at the reel. Any furnish preparation and refining methodology common to the papermaking industry can be utilized.

A 3% active solution Kymene 1142 is added to the refined NSK line prior to an in-line static mixer and 1% active solution of Wickit 1285, an ethoxylated fatty alcohol defoamer available from Ashland Inc. is added to the EUC furnish. The addition levels are 20 and 1 lbs active/ton of paper, respectively.

The NSK and EUC thick stocks are then blended into a single thick stock line followed by addition of 1% active carboxymethylcellulose (CMC) solution at 7 lbs active/ton of paper towel, and optionally, a softening agent may be added.

The thick stock is then diluted with white water at the inlet of a fan pump to a consistency of about 0.15% based on total weight of NSK and EUC fiber. The diluted fiber slurry is directed to a non-layered configuration headbox such that a wet web produced from the fiber slurry is formed onto a Fourdrinier wire (foraminous wire).

Dewatering occurs through the Fourdrinier wire and is assisted by deflector and vacuum boxes. The Fourdrinier wire is of a 5-shed, satin weave configuration having 84 machine-direction and 78 cross-direction monofilaments per inch, respectively. The speed of the Fourdrinier wire is about 675 fpm (feet per minute).

The embryonic wet web is transferred from the Fourdrinier wire at a fiber consistency of about 22% at the point of transfer to a patterned belt through-air-drying resin carrying fabric. To provide fibrous structure products of the present invention, the speed of the patterned through-air-drying fabric is about 18% slower than the speed of the Fourdrinier wire (for example a wet molding process). In another example, the embryonic wet web may be transferred to a patterned belt and/or fabric where the speed of the patterned through-air-drying fabric is approximately the same as the speed of the Fourdrinier wire.

Further de-watering is accomplished by vacuum assisted drainage until the web has a fiber consistency of about 26-28%.

While remaining in contact with the patterned drying fabric, the web is pre-dried by air blow-through pre-dryers to a fiber consistency of about 65% by weight.

After the pre-dryers, the semi-dry web is transferred to a Yankee dryer and adhered to the surface of the Yankee dryer with a sprayed creping adhesive. The creping adhesive is an aqueous dispersion with the actives consisting of about 2#/ton polyvinyl alcohol, and 0.5#/ton of release aid (CREPETROL® R6390). Crepe aids such as CREPETROL® A3025 may also be utilized. CREPETROL® A3025 and CREPETROL® R6390 are commercially available from Ashland Inc. (formerly Hercules Inc.). The creping adhesive is delivered to the Yankee surface at a rate of about 0.15% adhesive solids based on the dry weight of the web. The fiber consistency is increased to about 97% before the web is dry creped from the Yankee with a doctor blade.

The doctor blade has a bevel angle of about 45° and is positioned with respect to the Yankee dryer to provide an impact angle of about 101°. The Yankee dryer is operated at a temperature of about 177° C. and a speed of about 550 fpm. The fibrous structure is wound in a roll using a surface driven reel drum having a surface speed of about 610 fpm. In another example, the doctor blade may have a bevel angle of about 25° and is positioned with respect to the Yankee dryer to provide an impact angle of about 81° and the reel is run about 10% slower than the speed of the Yankee.

A wet compression-enhancing agent comprising Hyperfloc® NE823F represents an APE free, non-ionic water-in-oil emulsion (about 30% active-about 30% polyacrylamide, 30% water, 30% high boiling oil, and 10% surfactants) available from Hychem, Inc. under the trade name NE823F. A wet compression-enhancing agent comprising Hyperfloc® ND823 represents a dewatered emulsion consisting of (about 50% active-about 50% polyacrylamide, 40% high boiling oil and 10% surfactants). A blend (mixture) of the Hyperfloc® NE823F and ND823, for example via low shear mixing, result in a stable emulsion with no obvious settling. Formulations ranging from 100% NE823F to 100% ND823 were found to be stable. A 50/50 volume blend is prepared. The Hyperfloc® 50/50 volume blend emulsion of NE823F/ND823 is applied directly to an embossed surface of a fibrous structure via an extruder in converting utilizing an S-wrap configuration such that the extruder is positioned below the sheet with full wrap over the extruder head. Alternatively, dual side extrusion may be utilized.

The fibrous structure may be subsequently converted into an embossed, two-ply paper towel product having a basis weight of about 28-33 lbs/3000 ft² with fabric side out and/or wire side out.

Test Methods

Unless otherwise specified, all tests described herein including those described under the Definitions section and the following test methods are conducted on samples that have been conditioned in a conditioned room at a temperature of 23° C.±1.0° C. and a relative humidity of 50%±2% for a minimum of 2 hours prior to the test. All plastic and paper board packaging articles of manufacture must be carefully removed from the paper samples prior to testing. The samples tested are “usable units.” “Usable units” as used herein means sheets, flats from roll stock, pre-converted flats, and/or single or multi-ply products. Except where noted all tests are conducted in such conditioned room, all tests are conducted under the same environmental conditions and in such conditioned room. Discard any damaged product. Do not test samples that have defects such as wrinkles, tears, holes, and like. Samples conditioned as described herein are considered dry samples (such as “dry filaments”) for testing purposes. All instruments are calibrated according to manufacturer's specifications.

Basis Weight Test Method

Basis weight of a fibrous structure is measured on stacks of twelve usable units using a top loading analytical balance with a resolution of ±0.001 g. The balance is protected from air drafts and other disturbances using a draft shield. A precision cutting die, measuring 3.500 in ±0.0035 in by 3.500 in ±0.0035 in is used to prepare all samples.

With a precision cutting die, cut the samples into squares. Combine the cut squares to form a stack twelve samples thick. Measure the mass of the sample stack and record the result to the nearest 0.001 g.

The Basis Weight is calculated in lbs/3000 ft² or g/m² as follows:

Basis Weight=(Mass of stack)/[(Area of 1 square in stack)×(No. of squares in stack)]

For example,

Basis Weight (lbs/3000 ft²)=[[Mass of stack (g)/453.6 (g/lbs)]/[12.25 (in²)/144 (in²/ft²)×12]]×3000

or,

Basis Weight (g/m²)=Mass of stack (g)/[79.032 (cm²)/10,000 (cm²/m²)×12]

Report result to the nearest 0.1 lbs/3000 ft² or 0.1 g/m². Sample dimensions can be changed or varied using a similar precision cutter as mentioned above, so as at least 100 square inches of sample area in stack.

Moisture Content Test Method

The moisture content present in a fibrous structure, such as a fibrous structure is measured using the following Moisture Content Test Method. A fibrous structure or portion thereof (“sample”) is placed in a conditioned room at a temperature of 23° C.±1.0° C. and a relative humidity of 50%±2% for at least 24 hours prior to testing. Each fibrous structure sample has an area of at least 4 square inches, but small enough in size to fit appropriately on the balance weighing plate. Under the temperature and humidity conditions mentioned above, using a balance with at least four decimal places, the weight of the sample is recorded every five minutes until a change of less than 0.5% of previous weight is detected during a 10 minute period. The final weight is recorded as the “equilibrium weight”. Within 10 minutes, the sample is placed into a forced air oven on top of foil for 24 hours at 70° C.±2° C. at a relative humidity of 4%±□2% for drying. After the 24 hours of drying, the sample is removed and weighed within 15 seconds. This weight is designated as the “dry weight” of the sample.

The moisture content of the sample is calculated as follows:

$\%\mathrm{Moisture}\mathrm{in}\mathrm{sample}=100\%\times \frac{\left(\begin{array}{c}\mathrm{Equilibrium}\mathrm{weight}\mathrm{of}\mathrm{sample}-\\ \mathrm{Dry}\mathrm{weight}\mathrm{of}\mathrm{sample}\end{array}\right)}{\mathrm{Dry}\mathrm{weight}\mathrm{of}\mathrm{sample}}$

The % Moisture in sample for 3 replicates is averaged to give the reported % Moisture in sample. Report results to the nearest 0.1%.

Wet Compression Test Method

The Wet Compression Value of a fibrous structure and/or sanitary tissue product is measured by as follows. Caliper versus load data are obtained using a Thwing-Albert Model EJA Materials Tester, equipped with a 2000 g load cell and compression fixture including a compression table (compression platen). The compression fixture consists of the following: a load cell adaptor plate, 2000 gram overload protected load cell, load cell adaptor/foot mount 1.128 inch diameter presser foot, #89-14 anvil, 89-157 leveling plate, anvil mount, and a grip pin, all available from Thwing-Albert Instrument Company, Philadelphia, Pa. The compression foot has an area is 1 in². The instrument is run under the control of Thwing-Albert Motion Analysis Presentation Software (MAP V1,1,6,9). A test sample in the shape of a circle having a diameter of approximately 2 inches is cut from a usable unit to be tested (the test sample must be less than 2.5 inches in diameter (the diameter of the anvil) to prevent interference of the compression fixture with the test sample being tested). Care should be taken to avoid damage to the center portion of the test sample, which will be under test. Scissors or other suitable cutting tools may be used. Just before the test execution, the test sample is saturated with 4.5 g water/g fiber to produce a wet test sample. For the test, the wet test sample is centered on the compression table under the compression foot. The Tester is turned on. The compression-relaxation procedure is repeated 3 times on the same wet test sample. The compression and relaxation portion data are obtained using a crosshead speed of 0.1 inches/minute. The deflection of the load cell is obtained by running the test without a test sample being present on the compression table. This is generally known as the Steel-to-Steel data. The Steel-to-Steel data are obtained at a crosshead speed of 0.005 inch/minute. Crosshead position and load cell data are recorded between the load cell range of 5 grams and 300 grams for both the compression and relaxation portions of the test. Since the compression foot area is 1 in² this corresponded to a range of 5 g/in² to 300 g/in². The maximum pressure exerted on the wet test sample is 300 g/in². At 300 g/in² the crosshead reverses its travel direction. Crosshead position values are collected at selected load values during the test. These correspond to pressure values of 5, 10, 25, 50, 75, 100, 125, 150, 200, 300, 200, 150, 125, 100, 75, 50, 25, 10, 5 g/in² for the compression and the relaxation direction. During the compression portion of the test, crosshead position values are collected by the MAP software, by defining 10 traps (Trap 1 to Trap 10) at load settings of 5 (C5), 10 (C10), 25 (C25), 50 (C50), 75 (C75), 100 (C100), 125 (C125), 150 (C150), 200 (C200), 300 (C300) g/in². During the relaxation (return) portion of the test, crosshead position values are collected by the MAP software, by defining ten return traps (Return Trap 1 to Return Trap 10) at load settings of 300 (R300), 200 (R200), 150 (R150), 125 (R125), 100 (R100), 75 (R75), 50 (R50), 25 (R25), 10 (R10), 5 (R5) g/in². This cycle of compressions to 300 g/in² and return to 5 g/in² is repeated 3 times on the same wet test sample without removing the wet test sample. The 3 cycle compression-relaxation test is replicated 5 times for a given fibrous structure and/or sanitary tissue product using a fresh usable unit each time. The result (wet caliper of the wet test sample) is reported as an average of the 5 replicates for a given load. Again the caliper values are obtained for both the Steel-to-Steel and the wet test sample. Steel-to-Steel values are obtained for each batch of testing. If multiple days are involved in the testing, the values are checked daily. The Steel-to-Steel values and the wet test sample values are an average of 5 replicates at a given load.

Caliper values for a fibrous structure and/or sanitary tissue product are obtained by subtracting the average Steel-to-Steel crosshead trap value for a given load from the wet test sample crosshead trap value for a given load (for example at each trap point). For example, the caliper values from five individual replicates at a given load on each wet test sample are averaged and used to obtain the Wet Compression Value at a given load. Wet Compression Values are reported in millimeters (mm).

Charge Density Test Method

If one has identified or knows the soil adsorbing agent in and/or on an article of manufacture, then the charge density of the soil adsorbing agent can be determined by using a Mutek PCD-04 Particle Charge Detector available from BTG, or equivalent instrument. The following guidelines provided by BTG are used. Clearly, manufacturers of articles of manufacture comprising soil adsorbing agents know what soil adsorbing agent(s) are being included in their articles of manufacture. Therefore, such manufacturers and/or suppliers of the soil adsorbing agents used in the articles of manufacture can determine the charge density of the soil adsorbing agent.

1. Start with a 0.1% solution (0.1 g soil adsorbing agent +99.9 g deionized water). Preparation of dilute aqueous solutions in deionized water from inverse or dewatered inverse emulsions are performed as instructed by the supplier of the emulsions and is well known to one of ordinary skill in the art. Depending on the titrant consumption increase or decrease soil adsorbing agent content. Solution pH is adjusted prior to final dilution as charge density of many additives is dependent upon solution pH. A pH of 4.5 is used here for cationic polymers and between 6-7 for anionic polymers. No pH adjustment was necessary for the anionic polymers included in this study.

2. Place 20 mL of sample in the PCD measuring cell and insert piston.

3. Put the measuring cell with piston and sample in the PCD, the electrodes are facing the rear. Slide the cell along the guide until it touches the rear.

4. Pull piston upwards and turn it counter-clock-wise to lock the piston in place.

5. Switch on the motor. The streaming potential is shown on the touch panel. Wait 2 minutes until the signal is stable.

6. Use an oppositely charged titrant (for example for a cationic sample having a positive streaming potential: use an anionic titrant). Titrants are available from BTG consisting of 0.001N PVSK or 0.001N PolyDADMAC.

7. An automatic titrator available from BTG is utilized. After selecting the proper titrant, set the titrator to rinse the tubing by dispensing 10 mL insuring that all air bubbles have been purged.

8. Place tubing tip below the surface of the sample and start titration. The automatic titrator is set to stop automatically when the potential reaches 0 mV.

9. Record consumption of titrant, ideally, the consumption of titrant should be 0.2 mL to 10 mL; otherwise decrease or increase soil adsorbing agent content.

10. Repeat titration of a second 20 mL aliquot of the soil adsorbing agent sample.

11. Calculate charge demand (solution) or charge demand (solids);

$\mathrm{Charge}\mathrm{demand}\left(\mathrm{eq}\text{/}L\right)=\frac{V\mathrm{titrant}\mathrm{used}\left(L\right)\times \mathrm{Conc}.\mathrm{of}\mathrm{titrant}\mathrm{in}\mathrm{Normality}\left(\mathrm{eq}\text{/}L\right)}{\mathrm{Volume}\mathrm{of}\mathrm{sample}\mathrm{titrated}\left(L\right)}$ $\mathrm{Charge}\mathrm{demand}\left(\mathrm{eq}\text{/}g\right)=\frac{V\mathrm{titrant}\mathrm{used}\left(L\right)\times \mathrm{Conc}.\mathrm{of}\mathrm{titrant}\mathrm{in}\mathrm{Normality}\left(\mathrm{eq}\text{/}L\right)}{\mathrm{Wt}.\mathrm{solids}\mathrm{of}\mathrm{the}\mathrm{sample}\mathrm{or}\mathrm{its}\mathrm{active}\mathrm{substance}\left(g\right)}$

The charge density (charge demand) of a soil adsorbing agent is reported in meq/g units.

UL Viscosity Test Method

1) Reagents and Equipment

• • a) NaC1,
  • b) Deionized water,
  • c) 9 moles Ethoxylated Nonyl Phenol (for example SYNPERONIC NP9 from ICI surfactant),
  • d) Mechanical stirrer fitted with a stainless steel shaft equipped at the end with about 2 cm radius propeller-type blades,
  • e) High tall 600 ml beaker,
  • f) Disposable syringes (5 ml, 2 ml and 10 ml)
  • g) Balance with an accuracy of 0.001 g,
  • h) Thermometer,
  • i) 200 μm stainless steel screen.
    2) Preparation of an initial 0.5% polymer solution in water
  • a) Obtain a clean 600 ml beaker and fill it with 100 g of deionized water,
  • b) Start stirring with the mechanical stirrer at 500 rpm to create a vortex,
  • c) Calculate the weight of pure emulsion (W₀) required to obtain 0.5 g of polymer,

W₀=50/C

• •  C is the percentage of active matter in the emulsion
  • d) Withdraw approximately the weight (W₀) of emulsion into a plastic syringe,
  • e) Weigh accurately the syringe and record the weight filled (W_F),
  • f) Disperse rapidly the contents of the syringe into the vortex of the beaker,
  • g) Let stir 30 minutes,
  • h) Weigh the empty syringe and record the weight empty (W_E),
  • i) Calculate W=W_F−W_E.
    3) Preparation of a 0.1% solution of polymer in 1 M NaCl
  • a) Remove the beaker from the stirrer let the shaft and the blade, drain completely over the beaker,
  • b) Place the beaker on the balance and weigh in accurately:
    • i) 0.2 g of ethoxylated nonyl phenol
    • ii) (Q_E) g of deionized water, where Q_E=W×(9.7949×C−1)−100.2,
  • c) Let it stir again for 5 minutes at 500 rpm,
  • d) Then add the salt Q_s in g: let if stir for 5 minutes, where Q_s=0.585×W×C,
  • e) Resulting in a 0.1% solution of polymer in 1 M NaCl,
  • f) The polymer solution is now ready for measurement after filtration through a 200 μm screen.
    4) In the Case of a High Molecular Weight Emulsion (UL Viscosity greater than 7cP)
  • a) Prepare the solution at 0.5% as in step 2.
  • b) Remove the beaker from the stirrer let the shaft and the blade drain completely over the beaker,
  • c) Place the beaker on the balance and weight accurately:
    • i) 0.2 g of ethoxylated nonyl phenol,
    • ii) (Q_E) g of deionized water where Q_E=W×(9.7949×C−1)−100.2,
  • d) Let it stir again for 5 minutes at 850 rpm,
  • e) Then add the salt Q_s in g; let it stir for 5 minutes at 850 rpm, where Q_s=0.585×W×C
  • f) Resulting in a 0.1% solution of polymer in 1 M NaCl,
  • g) The polymer solution is now ready for viscosity measurement after filtration through a 200 μm screen.

5) Viscosity Measurement of Polymer Solution

• • The viscosity is determined by means of a Brookfield viscometer model LVT with the UL adapter and a spindle speed of 60 rpm
  • a) 16 ml of the solution are placed in the cup, and the temperature is adjusted to 23-25° C. the cup is then attached to the viscometer.
  • b) Let the spindle turn at 60 rpm until the reading is stable on the dial (about 30 seconds);
  • c) Read the value indicated on the dial:

Viscosity (in cP)=(reading−0.4)×0.1

The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”

Every document cited herein, including any cross referenced or related patent or application, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or Claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

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

Claims

1. A fibrous structure comprising a wet compression-enhancing agent such that the fibrous structure exhibits at least one of the following properties:

a. at least one Wet Compression value in a load value range of from 100 g to 300 g during the Compression Portion of the Wet Compression Test Method that is statistically greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent as measured according to the Wet Compression Test Method; and

b. at least one Wet Compression value in a load value range of from 50 g to 300 g during the Relaxation Portion of the Wet Compression Test Method that is statistically greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent as measured according to the Wet Compression Test Method.

2. The fibrous structure according to claim 1 wherein the fibrous structure exhibits at least one Wet Compression value in a load value range of from 100 g to 300 g during the Compression Portion of the Wet Compression Test Method that is statistically greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent as measured according to the Wet Compression Test Method.

3. The fibrous structure according to claim 1 wherein the fibrous structure exhibits a Wet Compression value of greater than 0.446 mm at a load value of 300 g during the Compression Portion of the Wet Compression Test Method as measured according to the Wet Compression Test Method.

4. The fibrous structure according to claim 1 wherein the fibrous structure exhibits a Wet Compression value of greater than 0.543 mm at a load value of 200 g during the Compression Portion of the Wet Compression Test Method as measured according to the Wet Compression Test Method.

5. The fibrous structure according to claim 1 wherein the fibrous structure exhibits a Wet Compression value of greater than 0.622 mm at a load value of 150 g during the Compression Portion of the Wet Compression Test Method as measured according to the Wet Compression Test Method.

6. The fibrous structure according to claim 1 wherein the fibrous structure exhibits a Wet Compression value of greater than 0.676 mm at a load value of 125 g during the Compression Portion of the Wet Compression Test Method as measured according to the Wet Compression Test Method.

7. The fibrous structure according to claim 1 wherein the fibrous structure exhibits a Wet Compression value of greater than 0.742 mm at a load value of 100 g during the Compression Portion of the Wet Compression Test Method as measured according to the Wet Compression Test Method.

8. The fibrous structure according to claim 1 wherein the fibrous structure exhibits a Wet Compression value of greater than 0.824 mm at a load value of 75 g during the Compression Portion of the Wet Compression Test Method as measured according to the Wet Compression Test Method.

9. The fibrous structure according to claim 1 wherein the fibrous structure exhibits a Wet Compression value of greater than 0.923 mm at a load value of 50 g during the Compression Portion of the Wet Compression Test Method as measured according to the Wet Compression Test Method.

10. The fibrous structure according to claim 1 wherein the fibrous structure exhibits at least one Wet Compression value in a load value range of from 50 g to 300 g during the Relaxation Portion of the Wet Compression Test Method that is greater than the corresponding Wet Compression value of the same fibrous structure void of the wet compression-enhancing agent as measured according to the Wet Compression Test Method.

11. The fibrous structure according to claim 1 wherein the fibrous structure exhibits a Wet Compression value of greater than 0.444 mm at a load value of 300 g during the Relaxation Portion of the Wet Compression Test Method as measured according to the Wet Compression Test Method.

12. The fibrous structure according to claim 1 wherein the fibrous structure exhibits a Wet Compression value of greater than 0.452 mm at a load value of 200 g during the Relaxation Portion of the Wet Compression Test Method as measured according to the Wet Compression Test Method.

13. The fibrous structure according to claim 1 wherein the wet compression-enhancing agent comprises a polymer.

14. The fibrous structure according to claim 13 wherein the polymer comprises a water-soluble polymer.

15. The fibrous structure according to claim 13 wherein the polymer comprises a polyacrylamide.

16. The fibrous structure according to claim 1 wherein the fibrous structure comprises a plurality of pulp fibers.

17. The fibrous structure according to claim 1 wherein the fibrous structure comprises a sanitary tissue product.

18. The fibrous structure according to claim 17 wherein the sanitary tissue product comprises a paper towel.

19. The fibrous structure according to claim 1 wherein the fibrous structure exhibits a Moisture content of less than 30% by weight of the fibrous structure.

20. The fibrous structure according to claim 1 wherein the wet compression-enhancing agent is retained by the fibrous structure during normal use when saturated with distilled water.