SOFT, LOW LINT, THROUGH AIR DRIED TISSUE AND METHOD OF FORMING THE SAME

A multi-ply through air dried tissue having a softness value of 91.0 or greater and a lint value of 5.0 or less. Each ply of the tissue has a first exterior layer that includes a wet end temporary wet strength additive in an amount of approximately 0.25 kg/ton and a wet end dry strength additive in an amount of approximately 0.25 kg/ton, an interior layer that includes a first wet end additive comprising an ionic surfactant, and a second wet end additive comprising a non-ionic surfactant, and a second exterior layer.

Skip to: Description  ·  Claims  · Patent History  ·  Patent History
Description
RELATED APPLICATION

This U.S. non-provisional patent application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 62/328,350, entitled Soft, Low Lint, Through Air Dried Tissue and Method of Forming the Same and filed on Apr. 27, 2016, the contents of which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention is directed to tissue, and in particular to a multilayer tissue including wet end additives.

BACKGROUND

Across the globe there is great demand for disposable paper products such as sanitary tissue and facial tissue. In the North American market, the demand is increasing for higher quality products offered at a reasonable price point. The quality attributes most important for consumers of disposable sanitary tissue is softness and strength. Another attribute desired by consumers is low lint, which refers to the amount of fibers that are liberated from the product during use.

Fabric crepe is the process of using speed differential between a forming and structured fabric to facilitate filling the valleys of the structured fabric with fiber, and folding the web in the Z-direction to create thickness and influence surface topography. Conventional creping is the use of a doctor blade to remove a web that is adhered to a steam heated cylinder (yankee dryer), coated with an adhesive chemistry, in conjunction with speed differential between the yankee dryer and reel drum to fold the web in the Z-direction to create thickness, drape, and to influence the surface topography of the web. The process of calendering, pressing the web between cylinders, will also affect surface topography. The surface topography can also be influenced by the coarseness and stiffness of the fibers used in the web, degree of fiber refining, as well as embossing in the converting process. Added chemical softeners and lotions can also affect the perception of smoothness by creating a lubricious surface coating that reduces friction between the web and the skin of the consumer.

Lint, or the amount of fibers liberated from the web during use can be affected by many things such as the overall strength of the web, the incorporation of natural or synthetic binders (especially in outer surface of the web which is exposed to direct contact with the consumer), the smoothness of the outer surface of the web, the size of the fibers or stratification of the fibers throughout the web, and the geometry of the creping doctor used to crepe the sheet from the yankee dryer.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a tissue manufacturing method that uses through air drying to produce a tissue with exceptional softness and low lint.

A multi-layer through air dried tissue according to an exemplary embodiment of the present invention comprises a first exterior layer, an interior layer and a second exterior layer. The interior layer includes a first wet end additive comprising an ionic surfactant and a second wet end additive comprising a non-ionic surfactant.

A multi-layer through air dried tissue according to another exemplary embodiment of the present invention comprises a first exterior layer comprised substantially of hardwood fibers, an interior layer comprised substantially of softwood fibers, and a second exterior layer comprised substantially of hardwood fibers. The interior layer includes a first wet end additive comprising an ionic surfactant and a second wet end additive comprising a non-ionic surfactant.

In at least one exemplary embodiment, the first exterior layer further comprises a wet end temporary wet strength additive.

In at least one exemplary embodiment, the first exterior layer further comprises a wet end dry strength additive.

In at least one exemplary embodiment, the second exterior layer further comprises a wet end dry strength additive.

In at least one exemplary embodiment, the second wet end additive comprises an ethoxylated vegetable oil.

In at least one exemplary embodiment, the second wet end additive comprises a combination of ethoxylated vegetable oils.

In at least one exemplary embodiment, the ratio by weight of the second wet end additive to the first wet end additive in the tissue is at least eight to one.

In at least one exemplary embodiment, the ratio by weight of the second wet end additive to the first wet end additive in the first interior layer is at most ninety to one.

In at least one exemplary embodiment, the ionic surfactant comprises a debonder.

In at least one exemplary embodiment, a 2-ply laminate of the tissue web has a softness (hand feel) of at least 91.

In at least one exemplary embodiment, a 2-ply laminate of the tissue web has a bulk softness of less than 10 TS7. j

In at least one exemplary embodiment, the wet end temporary wet strength additive comprises glyoxalated polyacrylamide.

In at least one exemplary embodiment, the wet end dry strength additive comprises amphoteric starch.

In at least one exemplary embodiment, the first exterior layer further comprises a dry strength additive.

In at least one exemplary embodiment, the first and second exterior layers are substantially free of any surface deposited softener agents or lotions.

In at least one exemplary embodiment, at least one of the first or second exterior layers comprises a surface deposited softener agent or lotion.

In at least one exemplary embodiment, the non-ionic surfactant has a hydrophilic-lipophilic balance of less than 10, and preferably less than 8.5.

In at least one exemplary embodiment, the first exterior layer is comprised of at least 20% by weight of softwood fibers.

In at least one exemplary embodiment, the interior layer is comprised of at least 75% by weight of softwood fibers.

Other features and advantages of embodiments of the invention will become readily apparent from the following detailed description, the accompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be described with references to the accompanying figures, wherein:

FIG. 1 is a schematic diagram of a three layer tissue in accordance with an exemplary embodiment of the present invention;

FIG. 2 is a block diagram of a system for manufacturing a single ply of the multi-ply tissue according to an exemplary embodiment of the present invention;

FIG. 3 is a block diagram of a system for manufacturing a multi-ply tissue from the single plies of tissue according to an exemplary embodiment of the present invention;

FIG. 4 illustrates a conventional creping blade;

FIG. 5 illustrates an example of a creping blade according to an exemplary embodiment of the present invention; and

FIG. 6 illustrates an example of a creping blade according to another exemplary embodiment of the present invention.

 DETAILED DESCRIPTION

Manufacturers of disposable paper products have long recognized a strong consumer demand for tissues, such as bath tissues and facial tissues, that are both soft and strong. Softness refers to the tactile sensation or “hand feel” that a consumer perceives when using the tissue. The strength is the ability of a paper web to retain its physical integrity during use. In making a tissue that is both soft and strong, there is typically a tradeoff between strength and softness. For example, manufacturers may make a tissue softer by adding more hardwood, which tends to be softer due to shorter fibers in the wood, but this reduces sheet strength.

While consumers tend to prefer the softer tissues, consumers are sensitive to the lint that is commonly liberated (released) from the soft tissues during use and left behind as residue on the user's skin or clothing. Conventional techniques used to reduce lint also make the tissue considerably less soft. For example, adding dry strength additive or temporary wet strength additive to the tissue or increasing the amount of long fiber softwood used to make the tissue, reduces lint but causes the tissue to be less soft. For this reason, it is desirable to further reduce the amount of lint released from a soft and strong tissue.

The reduction in lint is achieved in the present invention by controlling the surface fiber bonding to prevent the surface fibers from breaking away when the tissue is used. As described in further detail herein, the surface fiber bonding is controlled, for example, by supplying additives at the multi-layer headbox or by polymer/fiber migration during sheet formation. The resulting tissue satisfies consumers who prefer a soft but strong tissue with very low levels of lint.

The present invention is directed to a soft tissue made with a combination of a wet end added ionic surfactant and a wet end added nonionic surfactant. The tissue may be made up of a number of layers, including exterior layers and an interior layer. In at least one exemplary embodiment, pulp mixes for each tissue layer are prepared individually.

FIG. 1 shows a three layer tissue, generally designated by reference number 1, according to an exemplary embodiment of the present invention. The general structure and manufacturing process of the tissue 1 are as described in U.S. Pat. No. 8,968,517 (assigned to applicant), the contents of which are incorporated herein by reference in their entirety. The tissue 1 has external layers 2 and 4 as well as an internal, core layer 3. External layer 2 is composed primarily of hardwood fibers 20 whereas external layer 4 and core layer 3 are composed of a combination of hardwood fibers 20 and softwood fibers 21. The internal core layer 3 includes an ionic surfactant functioning as a debonder 5 and a non-ionic surfactant functioning as a softener 6. As explained in further detail below, external layers 2 and 4 also include non-ionic surfactant that migrated from the internal core layer 3 during formation of the tissue 1. External layer 2 further includes a dry strength additive 7. External layer 4 further includes both a dry strength additive 7 and a temporary wet strength additive 8.

Pulp mixes for exterior layers of the tissue are prepared with a blend of primarily hardwood fibers. For example, the pulp mix for at least one exterior layer is a blend containing about 70 percent or greater hardwood fibers relative to the total percentage of fibers that make up the blend. As a further example, the pulp mix for at least one exterior layer is a blend containing about 80 percent hardwood fibers relative to the total percentage of fibers that make up the blend.

Pulp mixes for the interior layer of the tissue are prepared with a blend of primarily softwood fibers. For example, the pulp mix for the interior layer is a blend containing about 70 percent or greater softwood fibers relative to the total percentage of fibers that make up the blend. As a further example, the pulp mix for the interior layer is a blend containing about 90-100 percent softwood fibers relative to the total percentage of fibers that make up the blend.

As known in the art, pulp mixes are subjected to a dilution stage in which water is added to the mixes so as to form a slurry. After the dilution stage but prior to reaching the headbox, each of the pulp mixes are dewatered to obtain a thick stock of about 95% water. In an exemplary embodiment of the invention, wet end additives are introduced into the thick stock pulp mixes of at least the interior layer. In an exemplary embodiment, a non-ionic surfactant and an ionic surfactant are added to the pulp mix for the interior layer. Suitable non-ionic surfactants have a hydrophilic-lipophilic balance of less than 10, and preferably less than or equal to 8.5. An exemplary non-ionic surfactant is an ethoxylated vegetable oil or a combination of two or more ethoxylated vegetable oils. Other exemplary non-ionic surfactants include ethylene oxide, propylene oxide adducts of fatty alcohols, alkylglycoside esters, and alkylethoxylated esters.

Suitable ionic surfactants include but are not limited to quaternary amines and cationic phospholipids. An exemplary ionic surfactant is 1,2-di(heptadecyl)-3-methyl-4,5-dihydroimidazol-3-ium methyl sulfate. Other exemplary ionic surfactants include (2-hydroxyethyl)methylbis[2-[(1-oxooctadecyl)oxy]ethyl]ammonium methyl sulfate, fatty dialkyl amine quaternary salts, mono fatty alkyl tertiary amine salts, unsaturated fatty alkyl amine salts, linear alkyl sulfonates, alkyl-benzene sulfonates and trimethyl-3-[(1-oxooctadecyl)amino]propylammonium methyl sulfate.

In an exemplary embodiment, the ionic surfactant may function as a debonder while the non-ionic surfactant functions as a softener. Typically, the debonder operates by breaking bonds between fibers to provide flexibility, however an unwanted side effect is that the overall strength of the tissue can be reduced by excessive exposure to debonder. Typical debonders are quaternary amine compounds such as trimethyl cocoammonium chloride, trymethyloleylammonium chloride, dimethyldi(hydrogenated-tallow)ammonium chloride and trimethylstearylammonium chloride.

After being added to the interior layer, the non-ionic surfactant (functioning as a softener) migrates through the other layers of the tissue while the ionic surfactant (functioning as a debonder) stays relatively fixed within the interior layer. Since the debonder remains substantially within the interior layer of the tissue, softer hardwood fibers (that may have lacked sufficient tensile strength if treated with a debonder) can be used for the exterior layers. Further, because only the interior of the tissue is treated, less debonder is required as compared to when the whole tissue is treated with debonder.

In an exemplary embodiment, the ratio of ionic surfactant to non-ionic surfactant added to the pulp mix for the interior layer of the tissue is between 1:4 and 1:90 parts by weight and preferably about 1:8 parts by weight. In particular, when the ionic surfactant is a quaternary amine debonder, reducing the concentration relative to the amount of non-ionic surfactant can lead to an improved tissue. Excess debonder, particularly when introduced as a wet end additive, can weaken the tissue, while an insufficient amount of debonder may not provide the tissue with sufficient flexibility. Because of the migration of the non-ionic surfactant to the exterior layers of the tissue, the ratio of ionic surfactant to non-ionic surfactant in the core layer may be significantly lower in the actual tissue compared to the pulp mix.

In an exemplary embodiment, a dry strength additive is added to the thick stock mix for at least one of the exterior layers. The dry strength additive may be, for example, amphoteric starch, added in a range of about 1 to 40 kg/ton. In another exemplary embodiment, a wet strength additive is added to the thick stock mix for at least one of the exterior layers. The wet strength additive may be, for example, glyoxalated polyacrylamide, commonly known as GPAM, added in a range of about 0.25 to 5 kg/ton. In a further exemplary embodiment, both a dry strength additive, preferably amphoteric starch and a wet strength additive, preferably GPAM are added to one of the exterior layers. Without being bound by theory, it is believed that the combination of both amphoteric starch and GPAM in a single layer when added as wet end additives provides a synergistic effect with regard to strength of the finished tissue to reduce linting. Other exemplary temporary wet-strength agents include aldehyde functionalized cationic starch, aldehyde functionalized polyacrylamides, acrolein co-polymers and cis-hydroxyl polysachharide (guar gum and locust bean gum) used in combination with any of the above mentioned compounds.

In addition to amphoteric starch, suitable dry strength additives may include but are not limited to glyoxalated polyacrylamide, cationic starch, carboxy methyl cellulose, guar gum, locust bean gum, cationic polyacrylamide, polyvinyl alcohol, anionic polyacrylamide or a combination thereof.

FIG. 2 is a block diagram of a system for manufacturing tissue, generally designated by reference number 100, according to an exemplary embodiment of the present invention. The system 100 includes an first exterior layer fan pump 102, a core layer fan pump 104, a second exterior layer fan pump 106, a headbox 108, a forming section 110, a drying section 112 and a calendar section 114. The first and second exterior layer fan pumps 102, 106 deliver the pulp mixes of the first and second external layers 2, 4 to the headbox 108, and the core layer fan pump 104 delivers the pulp mix of the core layer 3 to the headbox 108. As is known in the art, the headbox delivers a wet web of pulp onto a forming wire within the forming section 110. The wet web is laid on the forming wire with the core layer 3 disposed between the first and second external layers 2, 4.

After formation in the forming section 110, the partially dewatered web is transferred to the drying section 112, Within the drying the section 112, the tissue of the present invention may be dried using conventional through air drying processes. In an exemplary embodiment, the tissue of the present invention is dried to a humidity of about 7 to 20% using a through air drier manufactured by Metso Corporation, of Helsinki, Finland. In another exemplary embodiment of the invention, two or more through air drying stages are used in series. Without being bound by theory, it is believed that the use of multiple drying stages improves uniformity in the tissue, thus reducing tears.

In an exemplary embodiment, the tissue of the present invention is patterned during the through air drying process. Such patterning can be achieved through the use of a TAD fabric, such as a G-weave (Prolux 003) or M-weave (Prolux 005) TAD fabric.

After the through air drying stage, the tissue of the present invention may be further dried in a second phase using a Yankee drying drum. In an exemplary embodiment, a creping adhesive is applied to the drum prior to the tissue contacting the drum. The tissue adheres to the drum and is removed using a wear resistant coated creping blade with a creping shelf of 0.5 mm or less. The creping doctor set up angle is preferably 10 to 35 degrees, while the blade bevel is preferably 55 to 80 degrees.

To further illustrate the creping process, FIG. 4 shows a conventional creping blade application wherein a creping blade 401 is pressed against a steam heated drum 403 in order to crepe a tissue web 402. The blade 401 may be provided with a wear resistant material 404 at the blade tip. The available distance on the blade available for contact with the paper web is called the distance of the creping shelf or creping shelf distance. In FIG. 4 showing a conventional creping blade application, the distance of the creping shelf 415 is the same as the thickness of the creping blade 414.

In the creping process used in accordance with an exemplary embodiment of the present invention, as shown in FIG. 5, the distance of the creping shelf 515 has been reduced to 0.5 mm or less by beveling the non-contacting face of the blade 512. The angle of the bevel b is selected to obtain the desired creping shelf distance. It has been discovered that the distance of the creping shelf 515 can influence the web properties including tensile, bulk, and lint since the distance of the creping shelf directly influences the contact time between the blade 512 and web 502 and thus the forces imparted to the web by the blade. For example, it has been observed that as the creping shelf distance is decreased, there is a less tensile destruction at the blade and also a higher bulk generation.

In another exemplary embodiment, as shown in FIG. 6, a 25 degree blade set up angle c, which is measured from a normal line at the contact point between the blade tip and the drum to the face of the creping blade 605, a wear resistant coated tip blade with an 80 degree blade bevel d, and a 0.5 mm creping shelf distance 615 is utilized.

The wear resistant material is suitably a ceramic material, a cermet material, or a carbide material. For example, the wear resistant material may be selected from metal oxides, ceramic materials, silicates, carbides, borides, nitrides, and mixtures thereof. Particular examples of suitable wear resistant materials are alumina, chromia, zirconia, tungsten carbide, chromium carbide, zirconium carbide, tantalum carbide, titanium carbide, and mixtures thereof. The wear-resistant material is applied by thermal spraying, physical vapor deposition, or chemical vapor deposition.

The tissue may then be calendered in a subsequent stage within the calendar section 114. According to an exemplary embodiment, calendaring may be accomplished using a number of calendar rolls (not shown) that deliver a calendering pressure in the range of 0-100 pounds per linear inch (PLI). In general, increased calendering pressure is associated with reduced caliper and a smoother tissue surface.

According to an exemplary embodiment of the invention, a ceramic coated creping blade is used to remove the tissue from the Yankee drying drum. Ceramic coated creping blades result in reduced adhesive build up and aid in achieving higher run speeds. Without being bound by theory, it is believed that the ceramic coating of the creping blades provides a less adhesive surface than metal creping blades and is more resistant to edge wear that can lead to localized spots of adhesive accumulation. The ceramic creping blades allow for a greater amount of creping adhesive to be used which in turn provides improved sheet integrity and faster run speeds.

In addition to the use of wet end additives, the tissue of the present invention may also be treated with topical or surface deposited additives. Examples of surface deposited additives include softeners for increasing fiber softness and skin lotions. Examples of topical softeners include but are not limited to quaternary ammonium compounds, including, but not limited to, the dialkyldimethylammonium salts (e.g. ditallowdimethylammonium chloride, ditallowdimethylammonium methyl sulfate, di(hydrogenated tallow)dimethyl ammonium chloride, etc.). Another class of chemical softening agents include the well-known organo-reactive polydimethyl siloxane ingredients, including amino functional polydimethyl siloxane. zinc stearate, aluminum stearate, sodium stearate, calcium stearate, magnesium stearate, spermaceti, and steryl oil.

After the tissue basesheet is produced a laminate, composed of two webs/plies are laminated together in a face-to face relationship using an aqueous adhesive. The adhesives used to laminate the plies of absorbent structure can be water soluble of the group consisting of polyvinyl alcohol, polyvinyl acetate, starch based or mixtures thereof. The mixture is comprised of 1% to 10% by weight of the adhesives. Additionally; the mixture can contain up 10% by weight of a water soluble cationic resin selected from the group consisting of polyamide-epichlorohydrin resins, glyoxalated polyacrylamide resins, polyethyleneimine resins, polyethylenimine resins, or mixtures thereof. The remainder of the mixture is composed of water. This mixture is heated and maintained to a temperature between 90 deg F. to 150 deg F., preferably to 120 F.

The adhesive is heated and maintained at temperature utilizing an insulated stainless steel tank with heating elements uniformly distributed throughout the interior heating surface. The large amount of surface area heated provides uniform heating controlled by an adjustable thermostat. The tank is designed with an agitator that to ensure proper mixing and heat transfer.

The adhesive is applied using an applicator roll, aligned in an axially parallel arrangement with one of the two embossing rolls forming a nip therewith, such that the adhesive applicator roll is upstream of the nip formed between the two embossing rolls. The adhesive applicator roll transfers adhesive to the embossed webs on the embossing roll at the crests of the embossing knobs. The crests of the embossing knobs typically do not touch the perimeter of the opposing roll at the nip formed therebetween necessitating the addition of a marrying roll to apply pressure for lamination. The marrying roll forms a nip with the same embossing roll forming the nip with the adhesive applicator roll, downstream of the nip formed between the two embossing rolls.

According to an exemplary embodiment of the invention, the paper web on the converting lines may be treated with corona discharge before the embossing section. This treatment may be applied to the top ply and/or bottom ply. Nano cellulose fibers (NCF), nano crystalline cellulose (NCC), micro-fibrillated cellulose (MCF) and other shaped natural and synthetic fibers may be blown on to the paper web using a blower system immediately after corona treatment. This enables the nano-fibers to adsorb on to the paper web through electro-static interactions

As discussed, according to an exemplary embodiment of the invention, a debonder is added to at least the interior layer as a wet end additive. The debonder provides flexibility to the finished tissue product. However, the debonder also reduces the strength of the tissue web, which at times may result in sheet breaks during the manufacturing process. The relative softness of the tissue web results in inefficiencies in the rewind process that must be performed in order to correct a sheet break. Accordingly, as shown in FIG. 2, in an exemplary embodiment of the present invention, a switching valve 120 is used to control delivery of the debonder as a wet-end additive to the interior layer. In particular, when a sheet break is detected using, for example, conventional sheet break detection sensors, the switching valve 120 may be controlled to prevent further delivery of the debonder. This results in less flexibility and increased strength at the portion of the tissue web to be rewound, thereby allowing for a more efficient rewind process. Once the rewind process is completed, the switching valve may be opened to continue delivery of the debonder.

In addition to the use of a sheet break detection sensor, the switching valve 120 may also be controlled during turn up, the process whereby the tissue web is one transferred from on roll to another. The turn up process can result in higher stresses on the tissue web that normal operation, thus increasing the chance of sheet breaks. The switching valve 120 is turned off prior to turn up, thus increasing the strength of the tissue web. After the tissue web has begun winding on a new roll, the switching valve 120 is turned on again. The resulting roll of basesheet material thus has a section of higher strength tissue web at the center of the roll and may have a section of higher strength tissue on the outside of the roll. During finishing, the exterior section of higher strength tissue is removed and recycled. The interior section of higher strength tissue is not used to make a finished tissue. Thus, only the portion of the roll of basesheet tissue containing debonder is used to make finished tissue.

The below discussed values for basis weights, ball burst, MD and CD stretch and tensile strength, caliper, lint and softness of the inventive tissue were determined using the following test procedures:

Softness Testing

Softness of a 2-ply tissue web was determined using a Tissue Softness Analyzer (TSA), available from EMTECH Electronic GmbH of Leipzig, Germany. A punch was used to cut out three 100 cm2 round samples from the web. One of the samples was loaded into the TSA, clamped into place, and the TPII algorithm was selected from the list of available softness testing algorithms displayed by the TSA. After inputting parameters for the sample, the TSA measurement program was run. The test process was repeated for the remaining samples and the results for all the samples were averaged.

Ball Burst Testing

Ball Burst of a 2-ply tissue web was determined using a Tissue Softness Analyzer (TSA), available from EMTECH Electronic GmbH of Leipzig, Germany using a ball burst head and holder. A punch was used to cut out five 100 cm2 round samples from the web. One of the samples was loaded into the TSA, with the embossed surface facing down, over the holder and held into place using the ring. The ball burst algorithm was selected from the list of available softness testing algorithms displayed by the TSA. The ball burst head was then pushed by the EMTECH through the sample until the web ruptured and the grams force required for the rupture to occur was calculated. The test process was repeated for the remaining samples and the results for all the samples were averaged.

Stretch & MD, CD, and Wet CD Tensile Strength Testing

An Instron 3343 tensile tester, manufactured by Instron of Norwood, Mass., USA, with a 100N load cell and 25.4 mm rubber coated jaw faces was used for tensile strength measurement. Prior to measurement, the Instron 3343 tensile tester was calibrated. After calibration, 8 strips of 2-ply product, each one inch by four inches, were provided as samples for each test. When testing MD, the strips were cut in the MD direction and in the CD direction when testing CD. One of the sample strips was placed in between the upper jaw faces and clamp, and then between the lower jaw faces and clamp with a gap of 2 inches between the clamps. A test was run on the sample strip to obtain tensile and stretch. The test procedure was repeated until all the samples were tested. The values obtained for the eight sample strips were averaged to determine the tensile strength of the tissue. When testing CD wet tensile, the strips were placed in an oven at 105 deg Celsius for 5 minutes and saturated with 75 microliters of deionized water immediately prior to pulling the sample.

Lint Testing

Yankee side lint testing was performed in accordance with the procedure described in U.S. Pat. No. 5,611,890 to Vinson et al. (Cols. 25:55-31:2), which is incorporated herein by reference. The amount of lint generated from a tissue product was determined using a Sutherland Rub Tester, which may be obtained from Testing Machines, Inc. (Amityville, N.Y. 11701). The Sutherland Rub Tester uses a motor to rub a weighted felt 5 times over the stationary toilet tissue. The Hunter Color L value was measured before and after the rub test. The difference between these two Hunter Color L values was calculated as a lint value.

(a) Sample Preparation

Prior to the lint rub testing, the paper samples to be tested were conditioned according to Tappi Method #T4020M-88. Here, samples were preconditioned for 24 hours at a relative humidity level of 10 to 35% and within a temperature range of 22° to 40° C. After this preconditioning step, samples were conditioned for 24 hours at a relative humidity of 48 to 52% and within a temperature range of 22° to 24° C. This rub testing took place within the confines of the constant temperature and humidity room.

The tissue was first prepared by removing and discarding any product which might have been abraded in handling, e.g., on the outside of the roll. For multi-ply finished product, three sections with each containing two sheets of multi-ply product may be removed and set on the bench-top. For single-ply product, six sections with each containing two sheets of single-ply product may be removed and set on the bench-top. Each sample was then folded in half such that the crease was running along the cross direction (CD) of the tissue sample. For the multi-ply product, it was made sure that one of the sides facing out was the same side facing out after the sample was folded. In other words, the plies were not torn apart from one another to rub test the sides facing one another on the inside of the product. For the single-ply product, 3 samples with the off-Yankee side out were made up and 3 with the Yankee side out were made up. Which samples were Yankee side out and which were off-Yankee side out were kept track.

A 30″×40″ piece of Crescent #300 cardboard from Cordage Inc. (800 E. Ross Road, Cincinnati, Ohio, 45217) was obtained and cut out by a paper cutter into six pieces of cardboard of dimensions of 2.5″×6″. Each of the six cards was punctured with two holes by forcing the cardboard onto the hold down pins of the Sutherland Rub tester.

For single-ply finished product samples, each of the 2.5″×6″ cardboard pieces was centered and carefully placed on top of the six previously folded samples. It was made sure that the 6″ dimension of the cardboard was running parallel to the machine direction (MD) of each of the tissue samples.

For multi-ply finished product samples, three pieces of the 2.5″×6″ cardboard were used. Each of the cardboard pieces was centered and carefully placed on top of the three previously folded samples. Once again, it was made sure that the 6″ dimension of the cardboard was running parallel to the machine direction (MD) of each of the tissue samples.

One edge of the exposed portion of tissue sample was folded onto the back of the cardboard. This edge was secured to the cardboard with adhesive tape obtained from 3M Inc. (¾″ wide Scotch Brand, St. Paul, Minn.). The other over-hanging tissue edge was snugly folded over onto the back of the cardboard. While maintaining a snug fit of the paper onto the board, this second edge was taped to the back of the cardboard. This procedure was repeated for each sample.

Each sample was turned over and the cross direction edge of the tissue paper was taped to the cardboard. One half of the adhesive tape was in contact with the tissue paper while the other half adhered to the cardboard. This procedure was repeated for each of the samples. If the tissue sample breaks, tears, or becomes frayed at any time during the course of this sample preparation procedure, the sample was discarded and a new sample with a new tissue sample strip was used.

As for multi-ply converted product, 3 samples were placed on the cardboard. For single-ply finished product, 3 off-Yankee side out samples and 3 Yankee side out samples were placed on cardboard.

(b) Felt Preparation

A 30″×40″ piece of Crescent #300 cardboard was obtained from Cordage Inc. (800 E. Ross Road, Cincinnati, Ohio, 45217) and cut out by a paper cutter into six pieces of cardboard of dimensions of 2.25″×7.25″. Two lines were drawn parallel to the short dimension and down 1.125″ from the top and bottom most edges on the white side of the cardboard. The length of the line was carefully scored with a razor blade using a straight edge as a guide to a depth about half way through the thickness of the sheet. This scoring allowed the cardboard/felt combination to fit tightly around the weight of the Sutherland Rub tester. An arrow was drawn running parallel to the long dimension of the cardboard on this scored side of the cardboard.

Six pieces of black felt (e.g., F-55 or equivalent from New England Gasket, 550 Broad Street, Bristol, Conn. 06010) were cut to the dimensions of 2.25″×8.5″×0.0625″. The felt was placed on top of the unscored, green side of the cardboard such that the long edges of both the felt and cardboard were parallel and in alignment. It was made sure that the fluffy side of the felt was facing up. Also about 0.5″ was allowed to overhang the top and bottom most edges of the cardboard. Both overhanging felt edges were snuggly folded over onto the backside of the cardboard with Scotch brand tape. A total of six of these felt/cardboard combinations were prepared.

For best reproducibility, all samples were run with the same lot of felt. If a single lot of felt became completely depleted and a new lot of felt needed to be obtained, a correction factor was determined for the new lot of felt. To determine the correction factor, a representative single tissue sample of interest, and enough felt to make up 24 cardboard/felt samples for the new and old lots were obtained.

As described below and before any rubbing has taken place, Hunter L readings for each of the 24 cardboard/felt samples of the new and old lots of felt were obtained. The averages for both the 24 cardboard/felt samples of the old lot and the 24 cardboard/felt samples of the new lot were calculated.

Next, the 24 cardboard/felt boards of the new lot and the 24 cardboard/felt boards of the old lot were rub tested as described below. It was made sure that the same tissue lot number was used for each of the 24 samples for the old and new lots. In addition, sampling of the paper in the preparation of the cardboard/tissue samples was done so the new lot of felt and the old lot of felt were exposed to as representative as possible of a tissue sample. For the case of 1-ply tissue product, any product which might have been damaged or abraded was discarded. Next, 48 strips of tissue each two usable units (also termed sheets) long were obtained. The first two usable unit strip on the far left of the lab bench and the last of the 48 samples on the far right of the bench were placed. The sample to the far left was marked with the number “1” in a 1 cm by 1 cm area of the corner of the sample. The samples were continued to be marked consecutively up to 48 such that the last sample to the far right is numbered 48.

The 24 odd numbered samples for the new felt and the 24 even numbered samples for the old felt were used. The odd number samples were ordered from lowest to highest, and the even numbered samples were similarly ordered from lowest to highest. Now, the lowest number for each set was marked with a letter “Y.” The next highest number was marked with the letter “O.” Marking the samples continued in this alternating “Y”/“O” pattern. The “Y” samples were used for yankee side out lint analyses and the “O” samples were used for off-Yankee side lint analyses. For 1-ply product, there were a total of 24 samples for the new lot of felt and the old lot of felt. Of this 24, twelve were for yankee side out lint analysis and 12 were for off-yankee side lint analysis.

All 24 samples of the old felt were rubbed and their Hunter Color L values were measured as described below. The 12 yankee side Hunter Color L values for the old felt were recorded and averaged. The 12 off-yankee side Hunter Color L values for the old felt were also recorded and averaged. The average initial un-rubbed Hunter Color L felt reading was subtracted from the average Hunter Color L reading for the yankee side rubbed samples. This was the delta average difference for the yankee side samples. The average initial un-rubbed Hunter Color L felt reading was subtracted from the average Hunter Color L reading for the off-yankee side rubbed samples. This was the delta average difference for the off-yankee side samples. The sum of the delta average difference for the yankee-side and the delta average difference for the off-yankee side was calculated and this sum was divided by 2. This was the uncorrected lint value for the old felt. If there was a current felt correction factor for the old felt, it was added to the uncorrected lint value for the old felt. This value was the corrected Lint Value for the old felt.

All 24 samples of the new felt were rubbed and their Hunter Color L values were measured as described below. The 12 yankee side Hunter Color L values for the new felt were recorded and averaged. The 12 off-yankee side Hunter Color L values for the new felt were also recorded and averaged. The average initial un-rubbed Hunter Color L felt reading was subtracted from the average Hunter Color L reading for the yankee side rubbed samples. This was the delta average difference for the yankee side samples. The average initial un-rubbed Hunter Color L felt reading was subtracted from the average Hunter Color L reading for the off-yankee side rubbed samples. This was the delta average difference for the off-yankee side samples. The sum of the delta average difference for the yankee-side and the delta average difference for the off-yankee side was calculated and this sum was divided by 2. This was the uncorrected lint value for the new felt.

The difference between the corrected Lint Value from the old felt and the uncorrected lint value for the new felt was the felt correction factor for the new lot of felt. Adding this felt correction factor to the uncorrected lint value for the new felt was identical to the corrected Lint Value for the old felt.

The same type procedure was applied to two-ply tissue product with 24 samples run for the old felt and 24 run for the new felt. But, only the consumer used outside layers of the plies were rub tested. As noted above, it was made sure that the samples were prepared such that a representative sample was obtained for the old and new felts.

(c) Care of 4 Pound Weight

The four pound weight has four square inches of effective contact area providing a contact pressure of one pound per square inch. Since the contact pressure can be changed by alteration of the rubber pads mounted on the face of the weight, it is important to use only the rubber pads supplied by the manufacturer (e.g., Brown Inc., Mechanical Services Department, Kalamazoo, Mich.). These pads must be replaced if they become hard, abraded or chipped off.

When not in use, the weight must be positioned such that the pads are not supporting the full weight of the weight. It is best to store the weight on its side.

(d) Rub Tester Instrument Calibration

The Sutherland Rub Tester was first calibrated prior to use. First, the Sutherland Rub Tester was turned on by moving the tester switch to the “cont” position. When the tester arm is in its position closest to the user, the tester's switch was turned to the “auto” position. The tester was set to run 5 strokes by moving the pointer arm on the large dial to the “five” position setting. One stroke is a single and complete forward and reverse motion of the weight. The end of the rubbing block was in the position closest to the operator at the beginning and at the end of each test.

A tissue paper was prepared on cardboard sample as described above. In addition, a felt was prepared on cardboard sample as described above. Both of these samples were used for calibration of the instrument and were not used in the acquisition of data for the actual samples.

This calibration tissue sample was placed on the base plate of the tester by slipping the holes in the board over the hold-down pins. The hold-down pins prevent the sample from moving during the test. The calibration felt/cardboard sample was clipped onto the four pound weight with the cardboard side contacting the pads of the weight. It was made sure that the cardboard/felt combination was resting flat against the weight. This weight was hooked onto the tester arm and the tissue sample was gently placed underneath the weight/felt combination. The end of the weight closest to the operator was over the cardboard of the tissue sample and not the tissue sample itself. The felt rested flat on the tissue sample and was in 100% contact with the tissue surface. The tester was activated by depressing the “push” button.

A count of the number of strokes was kept and the starting and stopping position of the felt covered weight in relationship to the sample was observed and noted. If the total number of strokes was five and if the end of the felt covered weight closest to the operator was over the cardboard of the tissue sample at the beginning and end of this test, the tester was calibrated and ready to use. If the total number of strokes was not five or if the end of the felt covered weight closest to the operator was over the actual paper tissue sample either at the beginning or end of the test, this calibration procedure was repeated until 5 strokes are counted the end of the felt covered weight closest to the operator was situated over the cardboard at the both the start and end of the test.

During the actual testing of samples, the stroke count and the starting and stopping point of the felt covered weight were monitored and observed. Recalibration was made when necessary.

(e) Hunter Color Meter Calibration

The Hunter Color Difference Meter for the black and white standard plates was adjusted according to the procedures outlined in the operation manual of the instrument. Also the stability check for standardization as well as the daily color stability check was performed if this has not been done during the past eight hours. In addition, the zero reflectance must be checked and readjusted if necessary.

The white standard plate was placed on the sample stage under the instrument port. The sample stage was released and the sample plate was allowed to be raised beneath the sample port.

The “L-Y”, “a-X”, and “b-Z” standardizing knobs were used to adjust the instrument to read the Standard White Plate Values of “L”, “a”, and “b” when the “L”, “a”, and “b” push buttons were depressed in turn.

(f) Measurement of Samples

The first step in the measurement of lint was to measure the Hunter color values of the black felt/cardboard samples prior to being rubbed on the toilet tissue. The first step in this measurement was to lower the standard white plate from under the instrument port of the Hunter color instrument. A felt covered cardboard was centered, with the arrow pointing to the back of the color meter, on top of the standard plate. The sample stage was released, allowing the felt covered cardboard to be raised under the sample port.

Since the felt width was only slightly larger than the viewing area diameter, it was made sure that the felt completely covered the viewing area. After confirming complete coverage, the L push button was depressed. After waiting for the reading to stabilize, this L value was read and recorded to the nearest 0.1 unit.

If a D25D2A head was in use, the felt covered cardboard and plate were lowered, and the felt covered cardboard was rotated 90 degrees so the arrow points to the right side of the meter. Next, the sample stage was released and it was checked once more to make sure that the viewing area is completely covered with felt. The L push button was depressed and the L value was read and recorded to the nearest 0.1 unit. For the D25D2M unit, the recorded value was the Hunter Color L value. For the D25D2A head where a rotated sample reading was also recorded, the Hunter Color L value was the average of the two recorded values.

The Hunter Color L values for all of the felt covered cardboards were measured using this technique. If the Hunter Color L values were all within 0.3 units of one another, the average was taken to obtain the initial L reading. If the Hunter Color L values were not within the 0.3 units, those felt/cardboard combinations outside the limit were discarded. In that case, new samples were prepared and the Hunter Color L measurement was repeated until all samples were within 0.3 units of one another.

For the measurement of the actual tissue paper/cardboard combinations, the tissue sample/cardboard combination was placed on the base plate of the tester by slipping the holes in the board over the hold-down pins. The hold-down pins prevent the sample from moving during the test. The calibration felt/cardboard sample was clipped onto the four pound weight with the cardboard side contacting the pads of the weight. It was made sure that the cardboard/felt combination was resting flat against the weight. This weight was hooked onto the tester arm and the tissue sample was gently placed underneath the weight/felt combination. The end of the weight closest to the operator was over the cardboard of the tissue sample and not the tissue sample itself. The felt rested flat on the tissue sample and was in 100% contact with the tissue surface.

Next, the tester was activated by depressing the “push” button. At the end of the five strokes the tester automatically stopped. The stopping position of the felt covered weight in relation to the sample was noted. If the end of the felt covered weight toward the operator was over cardboard, the tester was operating properly. If the end of the felt covered weight toward the operator was over sample, this measurement was disregarded and recalibration was done as directed above in the Sutherland Rub Tester Calibration section.

The weight with the felt covered cardboard was removed and the tissue sample was inspected. If torn, the felt and tissue were discarded and the procedure was started over. If the tissue sample was intact, the felt covered cardboard was removed from the weight. The Hunter Color L value on the felt covered cardboard was determined as described above for the blank felts. The Hunter Color L readings for the felt after rubbing were recorded. All remaining samples were rubbed and their Hunter Color L values were measured and recorded.

After all tissues have been measured, all felts were removed and discarded. Felts strips were not used again. Cardboards were used until they were bent, torn, limp, or no longer had a smooth surface.

(g) Calculations

The delta L values were determined by subtracting the average initial L reading found for the unused felts from each of the measured values for the off-Yankee and Yankee sides of the sample. Multi-ply-ply product only rub one side of the paper. Thus, three delta L values were obtained for the multi-ply product. The three delta L values were averaged and the felt factor was subtracted from this final average. This final result is termed the lint for the fabric side of the 2-ply product.

For the single-ply product where both Yankee side and off-Yankee side measurements were obtained, the average initial L reading found for the unused felts was subtracted from each of the three Yankee side L readings and each of the three off-Yankee side L readings. The average delta for the three Yankee side values were calculated. The average delta for the three fabric side values were also calculated. The felt factor was then subtracted from each of these averages. The final results are termed a lint for the fabric side and a lint for the Yankee side of the single-ply product. By taking the average of these two values, an ultimate lint was obtained for the entire single-ply product.

Basis Weight

Using a dye and press, six 76.2 mm by 76.2 mm square samples were cut from a 2-ply product being careful to avoid any web perforations. The samples were placed in an oven at 105 deg C. for 5 minutes before being weighed on an analytical balance to the fourth decimal point. The weight of the sample in grams was divided by (0.0762 m)2 to determine the basis weight in grams/m2.

Caliper Testing

A Thwing-Albert ProGage 100 Thickness Tester, manufactured by Thwing Albert of West Berlin, N.J. was used for the caliper test. Eight 100 mm×100 mm square samples were cut from a 2-ply product. The samples were then tested individually and the results were averaged to obtain a caliper result for the base sheet.

The following two Examples illustrate the advantages of the present invention.

EXAMPLE 2-Ply Laminate Tissue with TSA>91.0 and Lint Value<5.0

Two webs of through air dried tissue were laminated to produce a roll of 2-ply sanitary (bath) tissue with 190 sheets each 4.0 inches long and 4.0 inches wide. The laminate was rolled on a roll that was 121 mm in diameter. The 2-ply tissue had the following product attributes: a Basis Weight of 37.8 g/m2, a Caliper of 0.517 mm, an MD tensile of 150 N/m, a CD tensile of 83 N/m, a ball burst of 195 grams force, a lint value of 4.86, an MD stretch of 13.4%, a CD stretch of 6.4%, a CD wet tensile of 9 N/m, a TSA of 91.9 and a TS7 of 8.26.

Each tissue web was multilayered with the fiber and chemistry of each layer selected and prepared individually to maximize product quality attributes of softness and strength. The first exterior layer, which was the layer that contacted the Yankee dryer, was prepared using 80% eucalyptus with 0.25 kg/ton of the amphoteric starch Redibond 2038 (Corn Products, 10 Finderne Avenue, Bridgewater, N.J. 08807) (for lint control) and 0.25 kg/ton of the glyoxylated polyacrylamide Hercobond 1194 (Ashland, 500 Hercules Road, Wilmington Del., 19808) (for strength when wet and for lint control). The remaining 20% of the first exterior layer was northern bleached softwood kraft fibers. The interior layer was composed of 40% northern bleached softwood kraft fibers, 60% eucalyptus fibers, and 1.0 kg/ton of T526, a softener/debonder (EKA Chemicals Inc., 1775 West Oak Commons Court, Marietta, Ga., 30062). The second exterior layer was composed of 20% northern bleached softwood kraft fibers, 80% eucalyptus fibers and 3.0 kg/ton of Redibond 2038 (to limit refining and impart Z-direction strength). The softwood fibers were refined at 115 kwh/ton to impart the necessary tensile strength.

The fiber and chemicals mixtures were diluted to solids of 0.5% consistency and fed to separate fan pumps, which delivered the slurry to a triple layered headbox. The headbox pH was controlled to 7.0 by addition of a caustic to the thick stock that was fed to the fan pumps. The headbox deposited the slurry to a nip formed by a forming roll, an outer forming wire, and inner forming wire. The slurry was drained through the outer wire, of a KT194-P design by Asten Johnson (4399 Corporate Rd, Charleston, S.C. USA), to aid with drainage, fiber support, and web formation. When the fabrics separated, the web followed the inner forming wire and dried to approximately 25% solids using a series of vacuum boxes and a steam box.

The web was then transferred to a structured fabric with the aid of a vacuum box to facilitate fiber penetration into the structured fabric to enhance bulk softness and web imprinting. The structured fabric used was a Prolux 005 design supplied by Albany (216 Airport Drive Rochester, N.H. USA), which has a 5 shed design with a warp pick sequence of 1, 3, 5, 2, 4, a 17.8 by 11.1 yarn/cm Mesh and Count, a 0.35 mm warp monofilament, a 0.50 mm weft monofilament, a 1.02 mm caliper, a permeability value of 640 cubic feet of air per minute (cfm), and a knuckle surface that was sanded to impart a 27% contact area with the Yankee dryer. The web was dried with the aid of two TAD hot air impingement drums to 85% moisture before being transferred to the Yankee dryer.

The web was held in intimate contact with the Yankee drum surface using an adhesive coating chemistry. The Yankee dryer was provided with steam at 3.0 bar while the installed hot air impingement hood over the Yankee dryer was blowing heated air at up to 450 degrees C. In accordance with an exemplary embodiment of the present invention, the web was creped from the yankee dryer at 10% crepe (speed differential between the yankee dryer and reel drum) using a blade with a wear resistant chromia titania material with a set up angle of 20 degrees, a 0.50 mm creping shelf distance, and an 80 degree blade bevel. In alternative embodiments, the web may be creped from the Yankee at 10% crepe using a ceramic blade at a pocket angle of 90 degrees. The caliper of the web was approximately 375 microns (single ply) before traveling through the calender to reduce the bulk to 275 microns (single ply). The web was cut into two of equal width using a high pressure water stream at 10,000 psi and was reeled into two equally sized parent rolls and transported to the converting process.

In the converting process, the two webs were plied together using mechanical ply bonding, or light embossing of the DEKO configuration (only the top sheet is embossed with glue applied to the inside of the top sheet at the high points derived from the embossments using and adhesive supplied by a cliché roll) with the second exterior layer of each web facing each other. The embossment coverage on the top sheet was 4%. The product was wound into a 190 sheet count roll at 121 mm.

An alternative process was also performed in which the web was not calendered on the paper machine before being converted as described above. In that case, the web was wound into a 176 count product at 121 mm and had approximately the same physical properties as described previously.

Comparative Example 2-Ply Laminate Tissue with TSA>91.0 and Lint Value<6.1

Two webs of through air dried tissue were laminated to produce a roll of 2-ply sanitary (bath) tissue with 190 sheets each 4.0 inches long and 4.0 inches wide. The laminate was rolled on a roll that was 121 mm in diameter. The 2-ply tissue further had the following product attributes: a Basis Weight of 38.2 g/m2, a Caliper of 0.525 mm, an MD tensile of 155 N/m, a CD tensile of 82 N/m, a ball burst of 222 grams force, a lint value of 6.04, an MD stretch of 11.9%, a CD stretch of 7.2%, a CD wet tensile of 8.7 N/m, a TSA of 92.2 and a TS7 of 8.5.

Each tissue web was multilayered with the fiber and chemistry of each layer selected and prepared individually to maximize product quality attributes of softness and strength. The first exterior layer, which contacted the Yankee dryer, was prepared using 95% eucalyptus with 0.25 kg/ton of the amphoteric starch Redibond 2038 (Corn Products, 10 Finderne Avenue, Bridgewater, N.J. 08807) (for lint control) and 0.25 kg/ton of the glyoxylated polyacrylamide Hercobond 1194 (Ashland, 500 Hercules Road, Wilmington Del., 19808) (for strength when wet and for lint control). The remaining 5% of the first exterior layer was northern bleached softwood kraft fibers. The interior layer was composed of 40% northern bleached softwood kraft fibers, 60% eucalyptus fibers, and 1.5 kg/ton of T526, a softener/debonder from EKA Chemicals Inc., 1775 West Oak Commons Court, Marietta, Ga. USA. The second exterior layer was composed of 20% northern bleached softwood kraft fibers, 80% eucalyptus fibers and 3.0kg/ton of Redibond 2038 (to limit refining and impart Z-direction strength). The softwood fibers were refined at 135 kwh/ton to impart the necessary tensile strength.

The fiber and chemicals mixtures were diluted to solids of 0.5% consistency and fed to separate fan pumps which delivered the slurry to a triple layered headbox. The headbox pH was controlled to 7.0 by the addition of a caustic to the thick stock that was fed to the fan pumps. The headbox deposited the slurry to a nip formed by a forming roll, an outer forming wire, and inner forming wire. The slurry was drained through the outer wire, which was a KT194-P design supplied by Asten Johnson (4399 Corporate Rd, Charleston, S.C. USA), to aid with drainage, fiber support, and web formation. When the fabrics were separated, the web followed the inner forming wire and was dried to approximately 25% solids using a series of vacuum boxes and a steam box.

The web was then transferred to a structured fabric which the aid of a vacuum box to facilitate fiber penetration into the structured fabric to enhance bulk softness and web imprinting. The structured fabric was a Prolux 005 design supplied by Albany (216 Airport Drive Rochester, NH USA) with a 5 shed design with a warp pick sequence of 1, 3, 5, 2, 4, a 17.8 by 11.1 yarn/cm Mesh and Count, a 0.35 mm warp monofilament, a 0.50 mm weft monofilament, a 1.02 mm caliper, with a 640 cfm and a knuckle surface that was sanded to impart 27% contact area with the Yankee dryer. The web was dried with the aid of two TAD hot air impingement drums to 85% moisture before being transferred to the Yankee dryer.

The web was held in intimate contact with the Yankee dryer surface using an adhesive coating chemistry. The Yankee dryer was provided with steam at 3.0 bar while the installed hot air impingement hood over the Yankee was blowing heated air up to 450 degrees C. In accordance with an exemplary embodiment of the present invention, the web was creped from the yankee at 10% crepe (speed differential between the yankee dryer and reel drum) using a blue steel material with a set up angle of 20 degrees, a 1.2 mm creping shelf distance, and an 80 degree blade bevel. In alternative embodiments, the web may be creped from the Yankee dryer at 10% crepe using a ceramic blade at a pocket angle of 90 degrees. The caliper of the web was approximately 375 microns (single ply) before traveling through the calender to reduce the bulk to 275 microns (single ply). The web was cut into two webs of equal width using a high pressure water stream at 10,000 psi and reeled into two equally sized parent rolls and transported to the converting process.

In the converting process, the two webs were plied together using mechanical ply bonding, or light embossing of the DEKO configuration (only the top sheet was embossed with glue applied to the inside of the top sheet at the high points derived from the embossments using and adhesive supplied by a cliché roll) with the second exterior layer of each web facing each other. The embossment coverage on the top sheet was 4%. The product was wound into a 190 sheet count product at 121 mm.

An alternative process was also performed in which the web was not calendered on the paper machine before being converted as described above. In that case, the web was wound into a 176 count product at 121 mm and had approximately the same physical properties as described previously.

Comparative Test Results from Commercially Available Products

Table 1 shows comparative test results for similar testing performed on various commercially available products. The test results are shown for basis weight, bulk, Dry MD and CD strength and stretch, Wet CD strength, Performance, Geometric Mean Tensile (GMT) strength, ball burst, TSA and lint value.

The tests confirm that the present invention is advantageous as all of the other tested products do not demonstrate the same levels of high softness and low lint. For example, all of the commercially available products demonstrated lower softness (i.e., lower TSA values) compared to the Example, and in some cases, higher lint values compared to the Example combined with the lower softness.

TABLE 1 Competitor Quality Attributes (6 samples tested and averaged for each month when tested) Basis MD MD CD Manufacture Paper Type Wt Bulk Strength Stretch Strength Charmin Sensitive January 2015 Proctor & TAD-2ply 42.17 540.13 124.91 18.40 75.62 Gamble February 2015 March 2015 Proctor & TAD-2 ply 42.45 643.00 116.52 21.88 76.18 Gamble April 2015 May 2015 June 2015 Safeway Home Ultra Soft January 2015 Clearwater TAD 2ply 48.66 540.03 202.50 18.40 105.20 February 2015 Clearwater TAD 2ply 50.24 555.82 168.09 22.63 110.62 March 2015 TAD 2ply April 2015 Clearwater TAD 2ply Tad 49.29 547.42 191.75 22.68 May 2015 TAD 2ply June 2015 Clearwater TAD 2ply Tad 48.70 525.23 194.68 19.35 Scott Extra Soft January 2015 February 2015 March 2015 April 2015 May 2015 June 2015 Kimberly-Clark UCTAD 1 ply 28.24 502.57 122.05 9.70 51.79 Scott-1000 January 2015 February 2015 March 2015 April 2015 May 2015 June 2015 Kimberly-Clark conventional 16.86 143.42 155.01 16.40 63.79 1ply Cottonelle January 2015 Kimberly-Clark UCTAD 1ply 39.30 714.42 107.06 15.31 63.11 February 2015 Kimberly-Clark UCTAD 1ply 40.92 627.43 130.55 18.54 55.79 March 2015 Kimberly-Clark UCTAD 1ply 38.10 634.77 155.52 16.87 74.20 April 2015 Kimberly-Clark UCTAD 1ply 40.35 651.78 134.39 15.44 70.47 May 2015 June 2015 Angel Soft January 2015 Georgia-Pacific conventional 37.28 413.88 181.34 25.57 65.07 2ply February 2015 Georgia-Pacific conventional 36.97 540.30 163.81 19.11 54.96 2ply March 2015 Georgia-Pacific conventional 36.46 494.80 124.45 19.74 49.64 2ply April 2015 Georgia-Pacific conventional 37.50 435.60 169.47 19.72 59.39 2ply May 2015 June 2015 Cottonelle Ultra January 2015 February 2015 Kimberly-Clark UCTAD 2ply 44.44 747.23 184.03 10.66 78.93 March 2015 April 2015 Kimberly-Clark UCTAD 2 ply 44.62 733.88 169.15 11.14 73.78 May 2015 June 2015 Kimberly-Clark UCTAD 2 ply 42.16 536.37 150.98 10.85 64.49 CD CD Ball Lint Stretch Wet Perf. GMT Burst TSA Value Charmin Sensitive January 2015 8.78 9.68 56.25 97.10 265.05 87.57 4.11 February 2015 March 2015 11.19 12.69 57.04 94.12 215.51 86.77 2.74 April 2015 May 2015 June 2015 Safeway Home Ultra Soft January 2015 6.36 10.91 55.78 145.77 182.15 86.88 7.77 February 2015 6.54 14.47 76.81 136.16 248.71 87.40 4.86 March 2015 April 2015 123.89 5.20 14.46 61.15 318.70 86.25 5.21 May 2015 June 2015 104.07 7.20 10.20 85.06 296.71 85.80 6.96 Scott Extra Soft January 2015 February 2015 March 2015 April 2015 May 2015 June 2015 11.55 6.96 76.41 79.44 199.84 81.70 2.96 Scott 1000 January 2015 February 2015 March 2015 April 2015 May 2015 June 2015 6.88 2.36 88.16 99.20 132.95 67.02 0.33 Cottonelle January 2015 10.35 13.23 67.05 82.10 163.95 84.18 5.80 February 2015 9.65 11.44 72.80 85.21 118.62 87.17 7.89 March 2015 13.17 11.42 88.03 107.20 213.83 83.60 5.21 April 2015 9.42 13.40 82.72 97.19 193.78 82.48 6.36 May 2015 June 2015 Angel Soft January 2015 9.50 10.52 62.63 108.53 234.55 78.73 2.05 February 2015 8.66 7.98 63.92 94.74 209.78 76.65 2.86 March 2015 9.58 4.68 60.13 78.34 203.55 79.82 2.14 April 2015 7.62 7.05 62.88 100.19 220.57 83.08 4.34 May 2015 June 2015 Cottonelle Ultra January 2015 February 2015 11.41 12.27 111.24 120.47 338.18 84.95 6.96 March 2015 April 2015 9.84 12.63 110.42 111.34 287.80 84.07 5.36 May 2015 June 2015 10.66 9.20 98.03 98.61 252.92 86.17 6.29

Now that embodiments of the present invention have been shown and described in detail, various modifications and improvements thereon will become readily apparent to those skilled in the art. Accordingly, the spirit and scope of the present invention is to be construed broadly and not limited by the foregoing specification.

Claims

1. A tissue comprising:

a laminate of at least two plies of a multi-layer through air dried tissue, the tissue having a softness value of 91.0 or greater and a lint value of 5.0 or less.

2. The tissue of claim 1, wherein the product has a bulk softness of less than 10 TS7.

3. The tissue of claim 1, wherein each ply of the multi-layer through air dried tissue comprises:

a first exterior layer comprising a wet end temporary wet strength additive in an amount of approximately 0.25 kg/ton and a wet end dry strength additive in an amount of approximately 0.25 kg/ton;
an interior layer comprising a first wet end additive comprising an ionic surfactant, and a second wet end additive comprising a non-ionic surfactant; and
a second exterior layer.

4. The tissue of claim 3, wherein the first exterior layer further comprises at least 75% by weight hardwood fibers.

5. The tissue of claim 4, wherein the first exterior layer further comprises at least 20% by weight of softwood fibers.

6. The tissue of claim 4, where the interior layer further comprises at least 40% by weight softwood fibers.

7. The tissue of claim 3, wherein the second wet end additive comprises one or more ethoxylated vegetable oils.

8. The tissue of claim 3, wherein the ratio by weight of the second wet end additive to the first wet end additive in the interior layer of the tissue is at least eight to one.

9. The tissue of claim 3, wherein the ratio by weight of the second wet end additive to the first wet end additive in the interior layer is at most ninety to one.

10. The tissue of claim 3, wherein the ionic surfactant comprises a debonder.

11. The tissue of claim 3, wherein the wet end temporary wet strength additive comprises glyoxalated polyacrylamide.

12. The tissue of claim 11, wherein the wet end dry strength additive comprises amphoteric starch.

13. The tissue of claim 3, wherein the second exterior layer comprises a wet end dry strength additive.

14. The tissue of claim 13, wherein the wet end dry strength additive comprises amphoteric starch.

15. The tissue of claim 3, wherein the interior layer is comprised of at least 75% by weight of softwood fibers.

16. The tissue of claim 3, wherein the second exterior layer further comprises a wet end dry strength additive.

17. The tissue of claim 3, wherein the second exterior layer further comprises a temporary wet strength additive.

18. The tissue of claim 3, wherein the second exterior layer further comprises a dry strength additive.

19. The tissue of claim 3, wherein the first exterior layer further comprises a dry strength additive.

20. The tissue of claim 3 having an MD tensile strength and a CD tensile strength of at least 35 N/m and having a basis weight of less than 40 gsm.

21. The tissue of claim 3 having an MD tensile strength and a CD tensile strength of at least 35 N/m and a caliper of less than 650 microns.

22. The tissue of claim 3, wherein the first and second exterior layers are substantially free of any surface-deposited softener agents or lotions.

23. The tissue of claim 3, wherein at least one of the first or second exterior layers comprises a surface-deposited softener agent or lotion.

24. The tissue of claim 3, wherein the non-ionic surfactant has a hydrophilic-lipophilic balance of less than 10.

25. The tissue of claim 3, wherein each of the at least two plies comprises an embossed area, wherein the embossed area occupies between approximately 3 to 15% of the total surface area of a surface of the ply.

26. The tissue of claim 1, wherein the tissue is one of a sanitary, bath or facial tissue.

Patent History
Publication number: 20170314206
Type: Application
Filed: Oct 13, 2016
Publication Date: Nov 2, 2017
Inventors: James E. Sealey, II (Belton, SC), Byrd Tyler Miller, IV (Easley, SC)
Application Number: 15/292,956
Classifications
International Classification: D21H 27/00 (20060101); D21H 27/38 (20060101); D21H 27/32 (20060101); D21H 27/00 (20060101); D21H 21/24 (20060101); D21H 21/20 (20060101); D21H 21/18 (20060101); D21H 21/14 (20060101); D21H 17/37 (20060101); D21H 17/28 (20060101); D21H 11/04 (20060101); D21H 27/40 (20060101); D21F 11/14 (20060101);