CN117157001A

CN117157001A - Wet laid disposable absorbent structure with high wet strength and method of making same

Info

Publication number: CN117157001A
Application number: CN202180091306.0A
Authority: CN
Inventors: 詹姆斯·E·西利二世; 凯文·布伦南; 伯德·泰勒·米勒四世; 詹姆斯·E·布拉德伯里; 贾斯丁·S·彭斯
Original assignee: First Quality Tissue LLC
Current assignee: First Quality Tissue LLC
Priority date: 2020-12-17
Filing date: 2021-12-17
Publication date: 2023-12-01

Abstract

A method of making an absorbent structure comprising mixing ultra high molecular weight ("UHMW") glyoxalated polyvinylamide adduct ("GPVM") and/or high molecular weight ("HMW") glyoxalated polyacrylamide and/or high cationic charge glyoxalated polyacrylamide ("GPAM") copolymer and high molecular weight ("HMW") anionic polyacrylamide ("APAM") with furnish during the stock preparation of a wet laid papermaking process.

Description

Wet laid disposable absorbent structure with high wet strength and method of making same

RELATED APPLICATIONS

The present application claims the priority and benefit of U.S. provisional application Ser. Nos. 63/199275 and 19/2021, filed on 12/17/2020, and entitled "Wet-laid disposable absorbent Structure with high Wet Strength and method of making same", the disclosure of which is incorporated herein by reference in its entirety.

Technical Field

The present application relates to a method of producing a wet laid disposable absorbent structure having high wet strength that is not prepared with a polyaminoamide-epihalohydrin (PAE) or polyamine-epichlorohydrin resin, and to a wet laid disposable absorbent structure having very low doses of PAE resin.

Background

Disposable tissues, napkins and tissues are absorbent structures that require strength to be maintained when wet. For example, paper towels need to maintain their strength when absorbing liquid spills, cleaning windows and mirrors, scrubbing countertops and floors, scrubbing and drying tableware, washing/cleaning bathroom sinks and toilets, and even drying/cleaning hands and faces. Disposable paper towels that perform these demanding tasks while being flexible are of competitive advantage because such towels are versatile and can be used as napkins and tissues. The same is true for napkins or tissues which can be a versatile product if the correct combination of quality attributes (where strength, absorbency and softness upon wetting are key attributes) can be obtained.

There are a number of industrial processes or techniques for producing these absorbent structures. A technique for forming a web of cellulose (or other natural or synthetic fiber type) including paper towels or wet wipes using Water is known as the Water-laid technique (Water-Laid Technologies). These techniques include through-air drying (TAD), uncreped through-air drying (uccad), conventional Wet Creping (CWC), conventional Dry Creping (CDC), ATMOS, NTT, QRT, and ETAD. A technique of forming a web including a tissue or a wet tissue using Air is called an airlaid technique (Air-Laid Technologies). To enhance the strength and absorbency of these tissues and wet tissues, more than one layer of web (or layer) may be laminated together using strictly mechanical processes or mechanical processes preferably using adhesives.

The absorbent structure may be produced using hydroentanglement techniques or airlaid techniques. Conventional dry-creping and conventional wet-creping water-laid web technologies are the primary methods of making these structures. These methods include forming a nascent web as the structure is formed, transferring the web to a dewatering felt, pressing the web there to remove moisture, and adhering the web to a Yankee Dryer (Yankee Dryer). The web is then dried and creped from the yankee dryer and then reeled. When creped at a solids content of less than 90%, the process is referred to as conventional wet creping. When creped at solids contents greater than 90%, the process is referred to as conventional dry creping. These processes may be further understood by reference to Yankee Dryer and Drying, A TAPPI PRESS analog, pages 215-219, the contents of which are incorporated herein by reference in their entirety. These processes are well understood and easy to operate at high speeds and productivity. The energy consumption per metric ton is low because almost half of the water is removed from the web by drainage and mechanical pressing. Unfortunately, sheet pressing also compacts the web, which reduces web thickness and causes reduced absorbency.

Through-air drying (TAD) and uncreped through-air drying (uccad) processes are wet-laid techniques that avoid compacting the web during drying, as compared to structures with similar basis weight and material input produced using CWC or CDC processes, resulting in absorbent structures with excellent caliper and absorbency. Patents describing creped through-air dried products include U.S. patent nos. 3994771, 4102737, 4191609, 4529480 and 5510002, while U.S. patent No. 5607551 describes uncreped through-air dried products. The contents of these patents are incorporated herein by reference in their entirety.

The remaining wet-laid processes, known as ATMOS, ETAD, NTT, STT and QRT, can also be used to produce absorbent structures. Each process/method utilizes some pressing to dewater the web or a portion of the web, resulting in an absorbent structure having absorbent capacity that, when all other variables are the same, is related to the amount of pressing used. ATMOS processes and products are recorded in U.S. Pat. Nos. 7744726, 6821391, 7387706, 7351307, 7951269, 8118979, 8440055, 7951269, or 8118979, 8440055, 8196314, 8402673, 8435384, 8544184, 8382956, 8580083, 7476293, 7510631, 7686923, 7931781, 8075739, 8092652, 7905989, 7582187, and 7691230, the contents of which are incorporated herein by reference in their entirety. The ETAD process and products are disclosed in U.S. patent nos. 7339378, 7442278, and 7494563, the contents of which are incorporated herein by reference in their entirety. NTT processes and products are disclosed in international patent application WO 2009/061079Al and U.S. patent application publication nos. US 2011/0180223Al and US 2010/0065234Al, the contents of which are incorporated herein by reference in their entirety. QRT processes are disclosed in U.S. patent application publication No. 2008/0156450Al and U.S. patent No. 7811418, the entire contents of which are incorporated herein by reference in their entirety. The STT method is disclosed in U.S. patent No. 7887673, the contents of which are incorporated herein by reference in their entirety.

All of the above wet laid techniques can produce single or multi-layered webs of absorbent structures. To form a multi-layer web, a two-layer or three-layer headbox is used, where each layer of the headbox can receive a different furnish flow.

In order to impart wet strength to absorbent structures in a wet laid process, cationic strength components are typically added to the furnish during the raw material preparation. The cationic strength component may comprise any polyethylenimine (polyethylenimine), polyaminoamide-epihalohydrin (preferably epichlorohydrin), polyamine-epichlorohydrin, polyamide, polyvinylamine, or polyvinylamide wet strength resin. Useful cationic thermosetting polyaminoamide-epihalohydrin ("PAE") and polyamine-epichlorohydrin resins are disclosed in U.S. patent nos. 5239047, 2926154, 3049469, 3058873, 3066066, 3125552, 3186900, 3197427, 3224986, 3224990, 3227615, 3240664, 3813362, 3778339, 3733290, 3227671, 3239491, 3240761, 3248280, 3250664, 3311594, 3329657, 3332834, 3332901, 3352833, 3248280, 3442754, 3459697, 3483077, 3609126, 4714736, 3058873, 2926154, 3877510, 4515657, 4537657, 4501862, 4147586, 4129528, 3855158, 5017642, 6908983, 5171795 and 5714552, the contents of which are incorporated herein by reference in their entirety. Cationic thermosetting PAE resins are the most widely used wet strength resins in wet laid absorbent structures such as tissues, napkins and tissues due to their chemical ability to produce high amounts of wet strength at affordable levels. Unfortunately, during the synthesis of these PAE resins, undesirable byproducts are produced. These byproducts are known as adsorbable organic halogens ("AOX"), including 1, 3-dichloro-2-propanol ("DCP") and 3-chloro-1, 2-propanediol ("CPD"). Known techniques for reducing the level of byproducts in PAE resins are disclosed in U.S. patent nos. 5470742, 5843763, 5871616, 6056855, 6057420, 6342580, 6554961, 7303652, 7175740, 7081512, 7932349, 8101710, 5516885, 6376578, 6429267, and 9719212, the contents of which are incorporated herein by reference in their entirety. See also Crisp, mark T.and Riehle, richard J, regulatory and sustainability initiatives lead to improved polyaminopolyamide-epichlorohydrin (PAE) wet-strength resins and paper products, TAPPI Journal, vol.17, no.9, september 2018.

Techniques have been developed to reduce AOX in PAE resins. Those skilled in the art are familiar with industrial terms such as G1 (first generation PAE with high AOX), G2 and G2.5 resins featuring reduced AOX (e.g., kymene ^TM 9 25NA wet strength resin and Kymene ^TM 217LX wet strength resin, available from Solenis 2475 Pinnacle Drive,Wilmington,DE 19803USA, telephone: +1-866-337-1533) and G3 resins (e.g. Kymene ^TM GHP20 wet strength resin, also available from Solenis). G2 technology is taught, for example, in U.S. patent nos. 5017642, 6908983, 5171795, and 5714552, the contents of which are incorporated herein by reference. The G2 resin typically has less than 1000ppm by weight DCP, while the G3 resin typically contains less than 10ppm by weight DCP. Those skilled in the art also note that in an attempt to reduce AOX, the efficiency and the resin ofFunctionality is compromised. A higher application amount is required to achieve the stretching objective.

As discussed, in order to impart wet strength to the absorbent structure in a wet-laid process, a cationic strength component may be added to the furnish during the raw material preparation. To impart the ability of a cationic strength resin, the addition of water-soluble carboxyl-containing polymers to the furnish along with the cationic resin is well known in the art. Suitable carboxyl-containing polymers include carboxymethyl cellulose ("CMC"), as disclosed in U.S. patent nos. 3058873, 3049469, and 3998690, the contents of which are incorporated herein by reference in their entirety.

Absorbent structures are also made using air-laid processes. The process spreads cellulose or other natural or synthetic fibers in an air stream directed onto a moving belt. The fibers are gathered together to form a web that can be thermally bonded with a resin or spray bonded and cured. The web is thicker, softer, more absorbent and stronger than wet laid. It is known to have textile-like surfaces and folds. Spin-laying is a variant of the air-laying process which produces a web in a continuous process in which plastic fibers (polyester or polypropylene) are spun (melted, extruded and blown) and then spread directly into the web in a continuous process. This technique is popular because it can produce faster tape speeds and reduce costs.

To further increase the strength of the absorbent structure, more than one layer of web (or layer) may be laminated together using strictly mechanical processes or mechanical processes preferably using adhesives. It will be generally understood that the absorbent capacity of a multi-layer structure may be greater than the sum of the absorbent capacities of the individual single layers. It is believed that this difference is due to the interlayer storage space created by the addition of additional layers. When producing a multi-layer absorbent structure, it is critical that the layers are bonded together in a manner that can withstand the forces encountered when the structure is used by a consumer. Scrubbing tasks such as cleaning countertops, dishware, and windows all exert forces on the structure, which can cause the structure to break and tear. When the interlayer adhesion fails, the layers move relative to each other, creating friction at the interface between the layers. Such frictional forces at the interface between the layers can cause structural failure (cracking or tearing), thereby reducing the overall effectiveness of the product in performing scrubbing and cleaning tasks.

There are many methods for joining or laminating multiple layers of absorbent structures to produce a multi-layer absorbent structure. One common method is embossing. Embossing is typically performed by one of three processes: tip-to-tip (or bump-to-bump), nested, or rubber-to-steel ("DEKO") embossing. Tip-to-tip embossing is described in commonly assigned U.S. patent No. 3414459, and a nested embossing process is described in U.S. patent No. 3556907, the entire contents of which are incorporated herein by reference in their entirety. Rubber to steel DEKO embossing comprises a steel roll having an embossing tip opposite a pressure roll (sometimes referred to as a back embossing roll) with elastomeric roll surfaces with the two roll axes being parallel and juxtaposed to form a nip in which the embossing tip of the embossing roll engages the elastomeric roll surface of the opposing roll, one sheet is passed through the nip using a joining roll clamped to the steel embossing roll, and a second unembossed sheet is laminated to the embossed sheet. In an exemplary rubber-to-steel embossing process, the adhesive application roller may be aligned with the patterned embossing roller in an axially parallel arrangement such that the adhesive application roller is upstream of the nip formed between the embossing and pressure rollers. The adhesive application roller transfers the adhesive onto the embossed web on the embossing roller at the top of the embossing bumps. The tops of the embossing bumps typically do not contact the periphery of the opposing idler rollers at the nip formed therebetween, so that an engagement roller needs to be added to apply pressure for lamination.

Other attempts to laminate absorbent structure webs include joining layers at bond lines, where the bond lines include individual pressure point bonds. As described in us patent No. 4770920, the spot bonds are formed by using a thermoplastic low viscosity liquid such as melted wax, paraffin wax, or hot melt adhesive. Another approach is to laminate the webs of absorbent structure by thermally bonding the webs together using polypropylene meltblown fibers as described in us patent 4885202. As described in U.S. patent nos. 3911173, 4098632, 4949688, 4891249, 4996091, and 5143776, other methods use a meltblown adhesive that is applied to one surface of an absorbent structure web in a spiral pattern, a stripe pattern, or a random pattern prior to pressing the one surface of the absorbent structure web against the web of the opposite surface of the second absorbent structure, the contents of which are incorporated herein by reference in their entirety.

There is a continuing need for absorbent products having high wet strength, absorbency and softness which are produced without producing any unwanted by-products.

Disclosure of Invention

It is an object of the present invention to provide a method for producing single or multi-ply cellulose-based wet laid disposable absorbent structures having high wet strength, absorbency and softness without or with very low doses of PAE wet strength resins containing or producing AOX by-products.

A retail tissue product according to an exemplary embodiment of the present invention comprises a bi-layer cellulosic sheet or web having a cross-directional wet strength of 80N/m to 200N/m and a bi-layer thickness of 600 microns to 1500 microns, wherein the retail tissue product contains 0 to 550ppb chlorohydrin and 0 to 0.09 weight percent polyaminoamide-epichlorohydrin.

In an exemplary embodiment, the tissue product has a transverse wet strength of 80N/m to 150N/m, a bilayer thickness of 700 microns to 1300 microns, and a tissue product having 38g/m ² To 50g/m ² Wherein the retail tissue product contains 50ppb to 550ppb of chloropropanediol and 0.01% to 0.04% by weight of a polyaminoamide-epihalohydrin.

A tissue or tissue product according to an exemplary embodiment of the present invention comprises: 95 to 99% by weight of cellulosic fibers; and 0.25 to 1.5 weight percent of an ultra-high molecular weight glyoxalated polyvinylamide adduct and a high molecular weight anionic polyacrylamide complex.

A tissue or tissue product according to an exemplary embodiment of the present invention comprises: 95 to 99% by weight of cellulosic fibers; 0.25 to 1.5 weight percent of an ultra-high molecular weight glyoxalated polyethylene amide adduct and a high molecular weight anionic polyacrylamide complex; and 0.03 to 0.5 wt% of a polyvinylamine.

A method of making an absorbent structure according to an exemplary embodiment of the present invention comprises: forming a feedstock mixture comprising cellulosic fibers, a high molecular weight anionic polyacrylamide, and an ultra high molecular weight glyoxalated polyvinylamide adduct; and at least partially drying the raw mixture using a wet-laid process to form a web, wherein no polyaminoamide-epihalohydrin is added to the raw mixture.

In an exemplary embodiment, the dichloropropanol concentration of the absorbent structure is less than 50ppb, and the chloropropanol concentration of the absorbent structure is less than 300ppb.

In an exemplary embodiment, the feedstock mixture further comprises an additive selected from lignin, laccase polymerized lignin, hemicellulose, polymerized hemicellulose, hemp stalk core, pectin, hydroxyethyl cellulose, carboxymethyl cellulose, guar gum, soy protein, chitin, polyvinylamine, polyethyleneimine, and combinations thereof.

An absorbent product according to an exemplary embodiment of the present invention comprises cellulosic fibers, dichloropropanol at a concentration of less than 50ppb and chloropropanol at a concentration of less than 300ppb, and has a wet transverse strength of from 80N/m to 200N/m, measured using the "Adipate test", which product is free of polyaminoamide-epihalohydrin.

In an exemplary embodiment, the absorbent product is a through-air dried tissue, napkin, or towel.

A tissue product according to one exemplary embodiment of the present invention comprises a double-layer creped through-air dried retail tissue having a transverse wet strength of 80N/m to 150N/m, a dry thickness of 700 microns to 1200 microns, 50 to 400 parts per billion of chloropropanol measured in the paper comprising the product, and 30 to 200 parts per billion of dichloropropanol measured in the paper, wherein a polyvinylamine is added to the wet end of a paper machine used to manufacture the tissue product.

The tissue product according to one exemplary embodiment of the present invention comprises a double-ply creped through-air dried retail tissue having a transverse wet strength of from 80N/m to 150N/m; a dry thickness of 700 microns to 1200 microns; 50 to 300 parts per billion of chloropropanol measured in paper making up the product; and 5 to 50 parts per billion of dichloropropanol measured in the paper, wherein no PAE resin is added to the wet end of a paper machine used to manufacture the tissue product.

Drawings

Various exemplary embodiments of the present invention will be described in detail with reference to the following drawings, in which:

FIG. 1 illustrates a pattern formed on an absorbent structure according to an exemplary embodiment of the present invention;

FIG. 2 is an exploded view of the apparatus used during a wet scrubbing test;

FIG. 3 illustrates the apparatus used during a wet scrubbing test;

FIG. 4 is an exploded view of the apparatus used during the wet scrubbing test;

FIG. 5 is a top view of a textured polymeric film used in the wet scrubbing test;

FIG. 6 is a flow chart illustrating a method of manufacturing an absorbent structure according to an exemplary embodiment of the present invention;

FIG. 7 illustrates a chemical reaction to produce a novel wet strength agent according to an exemplary embodiment of the present invention;

FIG. 8 illustrates a chemical reaction that produces a novel wet strength agent self-crosslinking and forms a large complex between GPAM and APAM according to an exemplary embodiment of the invention; and

FIG. 9 provides a table of measurement results for DCP, CDP and PAE for commercial tissue samples.

Detailed Description

For the purposes of the description provided herein, the term "low dose PAE resin" or "very low dose PAE resin" refers to absorbent structures containing less than 2.5kg PAE per diaphyseal metric ton of absorbent structure.

In an exemplary embodiment, the absorbent product is prepared without PAE, and thus, analysis by using adipic acid and/or glutaric acid specific methods, shows no presence of PAE (reaching the detectable limit of the measurement method), and furthermore, the product contains DCP and CPD down to undetectable levels of environmental background.

According to an exemplary embodiment, the method involves the use of ultra high molecular weight ("UHMW") glyoxalated polyvinylamide adducts ("GPVM") and/or high molecular weight ("HMW") glyoxalated polyacrylamides and/or high cationic charge glyoxalated polyacrylamide ("GPAM") copolymers and high molecular weight ("HMW") anionic polyacrylamides ("APAM") which are mixed with furnish during the raw material preparation of a wet laid papermaking process. HMW APAM is defined as having a molecular weight greater than 500000 daltons and may be an inverse emulsion product or a solution product, with the solution product being preferred. Methods of producing UHMW GPVM are described in U.S. patent No. 7875676B2 and U.S. patent No. 9879381B2, the contents of which are incorporated herein by reference in their entirety. These patents also characterize polymers and prepolymers, including molecular weights. Methods of preparing high cationic charge HMW GPAM copolymers are described in U.S. patent No. 9644320, the contents of which are incorporated herein by reference in their entirety. The patent also characterizes polymers and prepolymers, including molecular weights. The standard viscosity of the GPAM copolymer (measured from a 0.1 wt% solution of the polymer in 1M NaCl at 25 ℃ using a Brookfield viscometer with UL adapter at 60 rpm) can be less than 1.5 or less than 1.6 or less than 1.7 or less than 1.8. The combination of these two or three or more chemicals (referred to herein as wet strength agents) provides a wet tensile strength of at least 15% (e.g., 20% or 25% or 30%) of the dry tensile strength value of the absorbent product measured in the transverse or longitudinal direction of the absorbent product. In embodiments, polyvinylamine (PVAM) chemicals can also greatly enhance the effectiveness of wet strength systems without adding PAE or chlorinated organics to the mixture.

In exemplary embodiments, the method may further comprise adding various combinations of biopolymers to the furnish, including, but not limited to lignin, polymeric lignin, lignin polymerized with laccase, hemicellulose, polymeric hemicellulose, guar gum, cationic guar gum, CMC, chitin, chitosan, microfibrillated cellulose ("MFC"), pectin, hemp stalk core, and soy protein (or any protein source with increased protein MW or chemically linked to the biopolymers or pulp fibers listed above). The method may also involve using market pulp that has been coated with microfibrillated cellulose during or prior to the drying stage of the production market pulp sheet process. Microfibrillated cellulose and other biopolymers provide a large number of carboxyl and hydroxyl groups which can provide hydrogen bonds to both the cellulose fibers of the furnish and the wet strength agent to further improve the bonding network, thereby providing improved wet and dry strength. As the dry strength increases, refining of the cellulosic fibers may be minimized to increase the softness of the product. Furthermore, due to the high surface area of MFC, the absorption capacity of the final absorbent structure is improved. After mixing the wet strength agent, which may comprise additives and commercially available pulp coated with MFC, with the ingredients, the remaining steps of the wet-laid process are completed to produce the absorbent structure. An unexpected aspect of the present invention is the use of conventional dry strength additives to increase wet strength.

In another exemplary embodiment, the above process may be further enhanced or facilitated during the feedstock preparation step using a high shear mixing device, such as a medium consistency ("MC") pump (about 5 to 20% consistency). Further examples of this aspect include fiber furnish homogenizers primarily used for low consistency slurry mixing (about 0.1 to 5% consistency).

In another exemplary embodiment, rather than using UHMW GPVM, the method can include synthesizing and using a novel wet strength agent by reacting a vinylamide or CPAM polymer with glyoxal, oxidized lignin, and laccase. This reaction produces a cationic polymer similar to the ultra-high molecular weight glyoxalated polyvinylamide adduct but made more rigid and branched by incorporating lignin into the polymer. During synthesis, the incorporation of laccase aids in the polymerization of oxidized lignin. Polyvinylpyrrolidone (PVP), polyvinylamine (PVAm) and/or Anionic Polyacrylamide (APAM) may be reacted with the above polymers to enhance the rigidity of the network. Fig. 7 illustrates a chemical reaction that produces a novel wet strength agent according to an exemplary embodiment of the present invention.

When this novel wet strength agent is mixed with cellulosic fibers at the wet end of the wet laid process, the pendant aldehyde of the wet strength agent polymer (bonded to the polyamide skeleton via an amide bond) reacts with the hydroxyl groups on the cellulosic fibers to form hemiacetal bonds. The ionic bond between the anionic charge on the cellulose fibers and the cationic charge of the wet strength agent polymer also forms a hydrogen bond between the wet strength agent polymer and the cellulose fibers. Oxidized lignin incorporated into the wet strength agent polymer provides additional carboxyl groups to form hydrogen bonds with hydroxyl groups on the cellulose fibers. In addition, the pendant aldehyde groups of the wet strength agent polymer may react with the amide groups of an adjacent wet strength agent polymer during crosslinking to establish a network of wet strength polymer that is also bonded to the cellulose fibers, wherein the bonding has a significant restoring force to hydrolysis, thereby providing wet strength. The branched structure of the wet strength agent polymer also provides improved accessibility to various cellulosic fibers. Higher molecular weights are also preferred because the wet strength agent polymer increases in size to further improve accessibility. Finally, this novel polymer, which is highly branched in molecular weight, increases the structural rigidity of the absorbent product to maintain the three-dimensional structure of the product when wet, thereby maintaining the absorbency of the product. Fig. 8 illustrates a chemical reaction that produces a novel wet strength agent self-crosslinking and forms a large complex between GPAM and APAM according to an exemplary embodiment of the present invention.

In an exemplary embodiment, the complex of the anionic polyacrylamide resin and the aldehyde-functionalized polymer resin has a net anionic charge (as tested by the Mutek PCD03 test method). The amount of GPAM/APAM complex on or in the tissue or tissue product may be in the range of about 0.25% to 1.5% based on the total weight of the product.

The thickness of the absorbent product according to an exemplary embodiment of the present invention ranges from about 600 microns to about 1500 microns, or 700 microns to 1300 microns, or 725 microns to 1200 microns, or 735 microns to 1100 microns.

In exemplary embodiments, the absorbent product has a CD wet strength in the range of about 75N/m to about 200N/m, or 80N/m to 150N/m, or 85N/m to 145N/m.

In exemplary embodiments, the absorbent product has a wet thickness in the range of about 400 microns to about 800 microns, or 450 microns to 650 microns, or 470 microns to 575 microns.

In exemplary embodiments, the absorbent product has a basis weight of about 35gsm to about 65gsm, or 38gsm to 52gsm, or 38gsm to 50gsm, or 39gsm to 42gsm.

In exemplary embodiments, the absorbent product has a CD dry strength of about 275N/m to about 600N/m, or 325N/m to 525N/m, or 375N/m to 485N/m, or 380N/m to 450N/m.

In exemplary embodiments, the absorbent product has an absorbency of from about 11g/g to about 18g/g or from 12.5g/g to 16.0g/g or from 13.5g/g to 15.5g/g as measured according to the GATS method.

Absorbent products according to exemplary embodiments of the present invention contain from about 95% to about 99% by weight or from about 97% to about 99% by weight cellulosic fibers; from about 0.2 wt% to about 1.5 wt% or from about 0.05 wt% to about 1.5 wt% of a high molecular weight anionic polyacrylamide; and about 0.2 wt% to about 0.8 wt% or about 0.05 wt% to about 0.5 wt% of an ultra-high molecular weight glyoxalated polyethylene amide adduct and/or a high cationic HMW GPAM copolymer. In one embodiment, the GPAM has a cationic charge density of 0.6meq/g or less (tested by the Mutek PCD03 method). In exemplary embodiments, the absorbent product comprises a biopolymer in place of or in combination with the high molecular weight anionic polyacrylamide.

Absorbent products according to exemplary embodiments of the present invention are substantially free of CPD, DCP, and PAE. As used herein, the term "substantially free" is intended to mean that the paper comprises: CPD of less than 550 parts per billion (ppb) or about 50ppb to about 550 ppb; or less than about 200ppb or about 30ppb to about 200ppb DCP, or about 5ppb to 50ppb DCP in paper, and less than about 0.06% by weight PAE in paper or no PAE resin added to the wet-end of the paper machine. The PAE in the paper may be between 0.00 and 0.09%, or between 0.00 and 0.03%, or between 0.01 and 0.04% by weight. Although the invention can be implemented by adding 2.5 kg/ton of PAE resin at the wet end of the paper machine, the paper has the very low PAE or CPD/DCP described above while achieving high wet strength, high bulk and absorbency.

In an exemplary embodiment, the absorbent structure is a two-ply tissue roll product sold as a retail tissue.

Absorbent products according to exemplary embodiments of the present invention have a wet cross direction tensile strength of 75N/m to 200N/m, preferably 80N/m to 150N/m, most preferably 85N/m to 145N/m.

Absorbent structures made by the method according to exemplary embodiments of the present invention include, but are not limited to, disposable tissues, napkins, and facial products. The multiple layers of the absorbent structure may be laminated together using any of the lamination techniques described above to increase the overall absorbent capacity or softness.

Fig. 6 is a flow chart illustrating a method of manufacturing a tissue product according to an exemplary embodiment of the present invention. As shown, the tissue product was made on a wet-laid facility using a through-air drying process with a three-layer headbox. Tissues can be made from 75% northern bleached softwood kraft (NSBK) and 25% eucalyptus (eucalyptus) in all three layers. As shown in step 01, eucalyptus material is transferred from box a to blending tank 1. In step 02, NSBK is transported from box B to blending tank 2 and refined separately before blending into the layer (step 03). Also prior to blending into the layer, in step 04, NSBK is blended with a high cationic HMW GPAM copolymer (e.g., hercobond ^TM Plus 555 dry strength additive, available from Solenis 2475 Pinnacle Drive,Wilmington,DE 19803 USA phone: +1-866-337-1533). In step S06, NSBK mixed with the high cationic HMW GPAM copolymer is added to blending tank 2 to obtain a mixture of 75% NSBK and 25% eucalyptus. In step S07, the mixture is delivered to a headbox while simultaneously delivering HMW APAM (e.g., hercobond ^TM 2800 dry strength additives, available from Solenis) and a polyvinyl amine retention aid (e.g., hercobond ^TM 6950 dry strength additive from Solenis) was added to the mixture.

Test method

All tests were performed on prepared samples that had been conditioned in an air conditioning chamber at a temperature of 23.+ -. 1.0 ℃ and a relative humidity of 50.0%.+ -. 2.0% for at least 2 hours. Except for softness testing, which required 24 hours of conditioning at 23±1.0 degrees celsius and 50.0% ±2.0% relative humidity.

Ball burst test

Ball burst of the double ply tissue or tissue web was determined using a Tissue Softness Analyzer (TSA) available from Emtec Electronic GmbH of lybisin germany using a ball burst head and stand. The instrument is calibrated annually by an external provider according to an instrument manual. The balance on the TSA was verified and/or calibrated prior to burst analysis. Once the burst adapter and test ball (16 mm diameter) are attached to the TSA, the balance is zeroed. The test distance from the test ball to the sample was calibrated. Five round samples were cut from the web using a round punch with a diameter of 112.8 mm. One of the samples was loaded into the TSA with the embossed surface facing up on the stand and secured in place using a ring. The ball burst algorithm "burst Resistance" is selected from a list of available softness test algorithms displayed by the TSA. The TSA then pushes the ball bursting head through the sample until the web breaks and the newtonian force required for the break is calculated. The test procedure was repeated for the remaining samples, the results for all samples were averaged and then converted to gram force.

For more details on TSA operation, measurement ball burst and calibration instructions, please refer to the "handbook" or "operation instructions" handbook provided by Emtec.

Wet bulb burst test

Wet ball burst of the double ply tissue or tissue web was determined using a Tissue Softness Analyzer (TSA) available from Emtec Electronic GmbH of lybisin germany using a ball bursting head and stand. The instrument is calibrated annually by an external provider according to an instrument manual. The balance on the TSA was verified and/or calibrated prior to burst analysis. Once the burst adapter and test ball (16 mm diameter) are attached to the TSA, the balance is zeroed. The test distance from the test ball to the sample was calibrated. Five round samples were cut from the web using a round punch with a diameter of 112.8 mm. One of the samples was loaded into the TSA with the embossed surface facing up on the stand and secured in place using a ring. The ball burst algorithm "burst Resistance" is selected from a list of available softness test algorithms displayed by the TSA. A milliliter of water was placed in the center of the sample using a pipette and measurement was started after 30 seconds passed. The TSA then pushes the ball bursting head through the sample until the web breaks and the newtonian force required for the break is calculated. The test procedure was repeated for the remaining samples, the results for all samples were averaged and then converted to gram force.

Tensile and MD, CD and wet CD tensile Strength test

The Thwing-Albert EJA series tensile tester manufactured by Thwing Albert of Siberian, new Jersey, the Instron 3343 tensile tester manufactured by Instron of Norwood, massachusetts, or other suitable vertical elongation tensile tester configurable in various ways, typically using 1 inch or 3 inch wide paper towels or towel strips, can be used to measure tensile and MD, CD and wet CD tensile strength. The instrument is calibrated annually by an external provider according to an instrument manual. The collet separation speed and the distance between the collets (clamps) were verified before use and the balance was "zeroed". Before starting to measure the elongation, a pretension or relaxation correction of 5N/m has to be satisfied. After calibration, 6 strips of the 2-layer product were cut using a 25.4mm by 120mm die. When testing MD (machine direction) tensile strength, the strips were cut in the MD direction. When testing CD (cross direction) tensile strength, the strips were cut in the CD direction. One of the sample strips was placed between the faces of the upper jaw and clamped, then carefully straightened (without stretching the sample) and clamped between the faces of the lower jaw (freely depending from the upper jaw), with a gap or initial test span of 5.08cm (2 inches). The sample strips were tested using a grip separation speed of 2 inches/min to obtain tensile strength and peak stretch (as defined by TAPPI T-581om-17). The test procedure was repeated until all samples were tested. The values obtained for the six sample bars were averaged to determine the tensile strength and peak stretch in the MD and CD directions. When testing CD wet stretching, the strips were placed in an oven at 105 degrees celsius for 5 minutes and saturated with 75 microliters of deionized water in the center of the strips in the entire lateral direction immediately prior to stretching the sample.

Basis weight

Six 76.2mm by 76.2mm square samples were cut from the bi-layer product using dye and press, taking care to avoid any web perforation. The sample was placed in an oven at 105 degrees celsius for at least 3 minutes and then immediately weighed to the fourth place after the decimal point on an analytical balance. The sample weight in grams was multiplied by 172.223 to determine the weight in grams per square meter (g/m ² ) Basis weight in units. The samples were tested individually and the results averaged. The balance should be validated prior to use and calibrated annually by an external supplier according to an instrument manual.

Thickness test

Thickness testing was performed using a 89-2012 Thwing-Albert ProGage 100 thickness tester manufactured by Thwing Albert of sibirin, new jersey. The instrument is validated prior to use and calibrated annually by an external supplier according to an instrument manual. The thickness tester was used with a 2 inch diameter presser foot with a preset load of 95 grams per square inch, a measurement speed of 0.030 inches per second, a dwell time of 3 seconds, and a dead weight of 298.45g. 6 square samples of 100mm x 100mm were cut from the 2-ply product with the embossed pattern facing upward. The samples were then tested individually and the results averaged to obtain thickness results in microns.

Wet thickness

Thickness testing was performed using a 89-2012 Thwing-Albert ProGage 100 thickness tester manufactured by Thwing Albert of sibirin, new jersey. The instrument is validated prior to use and calibrated annually by an external supplier according to an instrument manual. The thickness tester was used with a 2 inch diameter presser foot with a preset load of 95 grams per square inch, a measurement speed of 0.030 inches per second, a dwell time of 3 seconds, and a dead weight of 298.45g. 6 square samples of 100mm x 100mm were cut from the 2 layers of product with the embossed pattern facing upward. Each sample was placed in a container that had been filled to a height of three inches with deionized water. The container is large enough that the sample can be placed on the water surface without having to fold the sample. The sample was placed in the water in the container for 30 seconds, then removed and then tested for thickness using ProGage. The samples were tested individually and the results averaged to obtain wet thickness results in microns.

Softness test

Softness of the double ply tissue or tissue web was determined using a Tissue Softness Analyzer (TSA) available from Emtec Electronic GmbH of lybi, germany. The TSA includes a rotor with vertical blades that rotate on a test piece to apply a defined contact pressure. The contact between the vertical blade and the test piece generates vibrations, which are sensed by the vibration sensor. The sensor then transmits the signal to the PC for processing and display. Frequency analysis in the range of about 200Hz to 1000Hz indicates the surface smoothness or texture of the test piece and is referred to as a TS750 value. Another peak in the frequency range between 6Hz and 7kHz represents the overall softness of the test piece and is referred to as the TS7 value. Both TS7 and TS750 values are in dB V ² rms is indicated. The stiffness of the sample is also calculated when the device measures the deformation of the sample under a specified load. The stiffness value (D) is expressed in mm/N. The device also calculates a Hand (HF) value corresponding to the softness perceived when someone touches the sample with his hand (the higher the HF value, the higher the softness). HF values are a combination of TS750, TS7 and stiffness of the sample measured by TSA and are calculated using an algorithm that also requires the thickness and basis weight of the sample. Different algorithms may be selected for different facial tissue, toilet paper and tissue products. Before testing, calibration checks should be performed using "TSA Leaflet Collection No.9" supplied by emtec. If the calibration check proves that calibration is necessary, "TSA Leaflet Collection No.10" is followed.

Five samples were cut from the web using a circular punch 112.8mm in diameter. One of the samples was loaded into the TSA, clamped in place (either outward or embossed layer up) and the TPII algorithm was selected from the list of available softness test algorithms displayed by the TSA when testing the bath towel, and the Facial II algorithm was selected when testing the towel. After inputting parameters of the sample (including thickness and basis weight), the TSA measurement program is run. The test procedure was repeated for the remaining samples and the results for all samples were averaged and the average HF number was recorded.

For a more detailed description of the procedure TSA, measurement softness and calibration, please refer to the "leaflet set" or "procedure instructions" manual provided by Emtec.

Absorbency test

Absorbency was tested using M/K GATS (weight absorption test System) manufactured by M/K Systems Inc. of Pebordi, mass.) using MK Systems GATS handbook at 29, 6/month 2020. The instrument is calibrated annually by an external provider according to a manual. Absorbency is expressed in grams of water absorbed per gram of absorbent product. The following steps were followed during the absorbency test:

the computer and GATS machine are turned on. The main power switch of the GATS is located on the left side of the front of the machine and when the power is on, the red light will light up. Ensure that the balance is open. The balance was not used to measure mass for at least 15 minutes from opening. Clicking on the "MK GATS" icon opens the computer program and clicking on "connect" after the program is loaded. If there is a connection problem, please ensure that the ports of the GATS and balance are correct. These can be seen in the full mode of operation. The upper reservoir of GATS needs to be filled with deionized water. The Velmex slide level of the wetting station was set at 6.5 cm. If the slide is not at the correct level, its movement can only be completed in the full mode of operation. Clicking the "direct mode" check box located in the upper left corner of the screen causes the system to exit the direct mode and enter the full operational mode. The level of the wetting station is adjusted downwards in a third window on the left side of the software screen. To move the slider 1 cm up or down at a time, the "1 cm up" and "1 cm down" buttons may be used. If a millimeter adjustment is required, press the shift key while switching the "1 cm up" or "1 cm down" icon. This will move the wetting station 1mm at a time. Clicking the "test options" icon ensures that the following set points are entered: 10.0mm selection "start dipping" is entered under "absorption" on the left hand side of the screen, 0.1 selection "total weight change (g)" is entered under "start", 0.05 selection rate (g) every 5 seconds is entered under "end", 1 selection "number of rises" and 10 selection regular rise (mm) are entered under "desorption" on the right hand side of the screen, and-0.03 selection rate (g) every 5 seconds is entered under "end". The water level in the main reservoir needs to be filled to the operating level before any series of tests can be performed. This involved setting the reservoir and the water contained in the reservoir to a total mass of 580 grams. Click on the "set" icon located in the upper left corner of the screen. It is necessary to lift the reservoir to de-tare or zero the balance itself. The feed and withdrawal pipes of the system are located on the sides and extend into the reservoir. Before lifting the reservoir, it is ensured that the top hatch on the balance is opened to prevent damage to the top of the balance or the overhead platform for weighing the sample. The balance side door is opened to lift the reservoir. Once the balance reading is stable, a message will be displayed and the reservoir placed again. Ensuring that the reservoir does not contact the balance wall. The side door of the balance is closed. The reservoir needs to be filled to obtain a mass of 580 grams. Once the reservoir is full, the system is ready for testing. At least four circular samples of 112.8mm diameter were obtained. Three will be tested and one will be available. Relevant sample information is entered in the "input materials i.d." section of the software. The software will automatically date and number the completed samples, with any user entered data in the middle of the file name. Clicking on the "run test" icon. The balance will automatically return to zero. The pre-cut sample is placed on an elevated platform to ensure that the sample does not contact the balance cover. After the balance load is stable, click "weigh". The sample was moved onto an aluminum test plate on a wetting station with the embossed face centered downward. Ensure that the sample does not touch the sides and place a cover over the sample. Click "wet sample". The wetting station will be lowered a preset distance to start the absorption (10 mm). When the absorption rate is less than 0.05 g/5 seconds, the absorption will end. When absorption stops, the wetting floor will rise for desorption. Desorption data for the test samples were not recorded. The saturated sample was removed and the wetting station was dried before the next test. Once the test is complete, the system will automatically refill the reservoir. Data generated for the sample is recorded. The data found for each sample are the dry weight of the sample (in grams), the normalized total absorption of the sample (in grams water/gram product) and the normalized absorption rate (in grams water/second). The procedure was repeated for three samples and the average total absorbency was reported.

Wet scrubbing

Wet scrubbing test was used to measure the durability of wet tissues. The test involved scrubbing the sample wet wipe with a wear tester and recording the number of revolutions required by the tester to break the sample. Multiple samples of the same product were tested and the average durability of the product was determined. The measured durability was then compared to similar durability measurements for other wet wipe samples.

Wet scrubbing tests were performed using a wear tester. The specific wear tester used was the M235 Martindale wear and pilling tester ("M235 tester") of SDL Atlas Textile Testing Solutions. The M235 tester provides a plurality of grind stations on which samples are subjected to grind testing, and a sample holder which grinds the tissue samples to enable simultaneous testing of the plurality of tissue samples. The motion plate is positioned above the polishing platen and moves the sample holder adjacent to the polishing platen for polishing.

During test preparation, eight (8) samples of paper towels were cut with a diameter of about 140mm (about 5.51 inches). In addition, four (4) pieces of samples of about 140mm (about 5.51 inches) in diameter were cut from a non-textured polymeric film having a thickness of about 82.+ -. 1. Mu.m. From Johnson &Johnson' sThe non-textured side of the vacuum sealed bag was used as a non-textured polymeric film. However, any non-textured polymeric film may be used, such as High Density Polyethylene (HDPE), low Density Polyethylene (LDPE), polypropylene (PP), or polyester, or the like. In addition, four (4) circular pieces of 38mm diameter were cut from the textured polymeric film with protruding channels on the surface to provide roughness. Textured polymeric films for this test were from SC Johnson +.>The textured side of the bag is vacuum sealed. Textured film having squareA pattern of shapes (fig. 5). The textured polymeric film used had protruding channels with a thickness of about 213±5pm and the textured film between protruding channels had a valley region with a film thickness of about 131±5 μm. The samples were cut using a cutting die of 140mm and 38mm diameter respectively and a click press.

An example of a polishing table for use with an M235 tester is shown in fig. 2. Fig. 2 shows an exploded view of the attachment of a tissue sample to an abrasive table 202. To insert each sample to be tested into the polishing station, the motion plate of the polishing station is removed from the tester, the clamping ring 214 is unscrewed, a smooth piece of polymer film 210 is placed on the polishing station 202, and then a tissue sample 212 is placed on top of the smooth polymer film 210. As shown in fig. 3, a loading weight 215 is temporarily placed on top of the sample 212 on the grinding table 202 to hold everything in place while a clamping ring 214 is reattached to the grinding table 202 to hold the tissue sample 212 in place.

Referring to FIG. 4, for each polishing station 202 in the M235 tester, there is a corresponding sample holder for performing the wear test. Sample holder insert 218 is assembled by inserting a piece of textured polymeric film 216 into sample holder insert 218, placing sample holder insert 218 under sample holder body 220 and holding it in place under sample holder body 220 with a sample holder nut (not shown). Spindle 222 is mounted to the top center of sample holder body 220. In fig. 5, a top view of the textured polymeric film 216 of fig. 4 is shown.

The M235 tester was then turned on and set to a cycle time of 200 revolutions. 0.5mL of water was placed on each tissue sample. After a wait of 30 seconds, the scrub test is started, thereby rotating sample holder 206 by 200 revolutions. The number of revolutions taken to break each sample (the "web scrub resistance" of the sample) on each grinding table 202 is recorded. The results for the samples of each product were averaged and then the products were rated based on the average.

Test method for PAE detection in product

PAE can be measured by the method taught in "Determination of wet-strength resin in Paper by pyrolysis-gas chromatography" (Paper Properties, month 2 1991, tappi Journal, pages 197-201), which method is incorporated herein by reference in its entirety. PAE is measured indirectly by measuring cyclopentanone. The vertical micro-oven pyrolyzer (Yanagimoto GP-1018) was directly connected to a gas chromatograph equipped with a flame ionization detector and a flame thermionic detector (Shimadzu GC 9A). About 0.5mg of the rolled paper product or towel is pyrolyzed under a stream of nitrogen or helium carrier gas. The pyrolysis temperature was empirically set at 500 ℃. A fused silica capillary column (50 m x 0.25mm id, quadrex) was used, which was coated with a free fatty acid phase (FFAP, 0.25 μm thick) immobilized by chemical crosslinking. The carrier gas flow rate of 50 ml/min at the pyrolyzer was reduced to 1 ml/min at the capillary column through the flow divider. The column temperature was initially set at 40 ℃ and then run at a rate of 4 ℃ per minute to 240 ℃. The pyrolysis chromatographic peaks were identified using a gas chromatograph-mass spectrometer (Shimadzu QP-1000) with an electron impact ionization source. Cyclopentanone standards were prepared and a calibration curve was generated, and then a roll paper commodity or tissue sample was measured against the curve.

The product may be contaminated with PAE in the yankee coating. To eliminate this problem, the above test method was repeated 10 times and the intermittent high level of PAE data was eliminated. Another method of determining whether PAE is caused by surface yankee coating contamination is to use a tape layer purity test to remove yankee layers from two layers of a two-layer tissue, napkin, or facial tissue product. Care must be taken to ensure that the surface contact of the yankee surface is that removed by the tape. Some tissue products may be reverse laminated with the yankee side placed therein or the yankee side laminated with the yankee side. After removal of the yankee layer, the test methods described above were performed on the samples.

Alternatively, PAE tests can be performed by koolwaterstop straat 1, 6161RA Geleen, intertek Polychemlab b.v. in the netherlands.

Typical sample analysis includes the following: 0.2 g of sample material was added to 10ml of 37% aqueous hydrochloric acid, which contained pimelic acid (CAS 111-16-0) as an internal standard. The mixture was then submitted to a microwave for 2 hours at 150 ℃. The resulting solution was transferred to a 50ml flask and measured by liquid chromatography-mass spectrometry using adipic acid (CAS 124-04-9) and glutaric acid (CAS 110-94-1) as external standards. No internal standard correction was used. All PAE values in this patent application are expressed as weight percent of the sum of adipic acid and glutaric acid values.

Test method for detecting DCP and CPD

The DCP and CPD were measured by the ACOC official method 2000.01, which is incorporated herein by reference in its entirety. A1 mg/ml stock solution of CPD was prepared by weighing 25mg CPD (98% isotopic purity, available from Sigma-Aldrich) into a 25ml volumetric flask and diluting to volume with ethyl acetate. 100 μg/ml of CPD intermediate standard solution was prepared by diluting 1 ml of CPD stock solution with 9 ml of ethyl acetate. A2. Mu.g/ml CPD addition standard solution was prepared by pipetting 2ml of the CPD intermediate standard solution into a 100ml volumetric flask and diluting to volume with ethyl acetate. 25mg of CPD-d ₅ Weigh into a 25ml volumetric flask and dilute to volume with ethyl acetate to prepare 1mg/ml CPD-d ₅ Internal standard stock solution. By diluting 1 ml CPD-d in 100ml ethyl acetate ₅ Preparation of internal standard stock solution 10. Mu.g/ml CPD-d ₅ An internal standard working solution. CPD calibration solutions were prepared by pipetting 0, 12.5, 25, 125, 250 and 500. Mu.l aliquots of 100. Mu.g/ml of the intermediate standard solution into 25ml volumetric flasks and diluting to volume with 2, 4-trimethylpentane to obtain CPD concentrations of 0.00, 0.05. Mu.g/ml, 0.10. Mu.g/ml, 0.50. Mu.g/ml, 1.00. Mu.g/ml and 2.00. Mu.g/ml, respectively.

A5M sodium chloride solution was prepared by dissolving 290g NaCl (Fisher) in 1L water. An ether-hexane solution was prepared by mixing 100ml of ether with 900ml of hexane.

The product was prepared by adding 10g (to the nearest 0.01 g) of the test portion of a roll towel or towel to a beaker. 100 μl of internal standard working solution was added. 5M NaCl solution was added to a total weight of 40g and blended into a uniform mixture by crushing all the pieces using a spatula. The product was placed in an ultrasonic bath for 15 minutes. The bath was covered and the product was soaked for 12 to 15 hours. EXTRELUT ^TM Refill (available through EM Science)Added to 20g of the prepared product and thoroughly mixed with a spatula. The mixture was poured into a 40X 2cm id glass chromatograph tube with sintered disc and tap. The tube was briefly stirred by hand to compact the contents, then covered with a 1cm layer of sodium sulfate (Fisher) and left to stand for 15 to 20 minutes. The nonpolar contents were eluted with 80ml of diethyl ether-hexane. Unrestricted flow is allowed, except for powder soups, which flow is restricted to about 8ml/min to 10ml/min. The tap was closed when the solvent reached the sodium sulfate layer and the collected solvent was discarded. CPD was eluted with 250ml of diethyl ether at a flow rate of about 8 ml/min. 250ml of eluate were collected in a 250ml volumetric flask. 15g of anhydrous sodium sulfate was added, and the flask was left for 10 to 15 minutes.

The eluate was filtered through Whatman No. 4 filter paper into a 250ml round bottom or pear-shaped flask. The extract was concentrated to about 5ml on a rotary evaporator at 35 ℃. The concentrated extract was transferred to a 10ml volumetric flask with diethyl ether and diluted to volume with diethyl ether. A small amount (about the spatula tip) of anhydrous sodium sulfate was added to the flask and shaken, and then allowed to stand for 5 to 10 minutes. Using a 1ml air tight syringe, 1ml of extract was transferred to a 4ml vial. The solution was evaporated to dryness under a nitrogen flow at below 30 ℃. 1ml of 2, 4-trimethylpentane and 0.05ml of heptafluorobutyryl imidazole were immediately added and the vial was sealed. The vials were shaken for a few seconds with a tube shaker and heated in an occlusion heater at 70℃for 20 minutes. The mixture was cooled to <40 ℃ and 1ml distilled water was added. The mixture was shaken with a tube shaker for 30 seconds. The phases were allowed to separate and then shaking was repeated. 2, 4-trimethylpentane was phase shifted into a 2ml vial, anhydrous sodium sulfate at the tip of the spatula was added and shaken, and the vial was allowed to stand for 2 to 5 minutes. The solution was transferred to a new 2ml vial for GC/MS. Parallel method blank tests containing 20g of 5M NaCl solution were performed for each batch.

Calibration samples were prepared by: a set of 4ml vials was charged with 0.1ml of each calibration solution, 10. Mu.l of CPD internal working standard and 0.9ml of 2, 4-trimethylpentane, and then derivatised as described above.

The calibration samples and product samples were analyzed on a gas chromatograph/mass spectrometer. The gas chromatograph is equipped with a split/no split detector. The column was nonpolar, 30m 0.25mm,0.25mm film thickness (J & W Scientific) DB-5ms, or equivalent. The recommended temperature program is an initial temperature of 50 ℃ for 1 minute, increasing the temperature to 90 ℃ at a rate of 2 ℃/minute; raising the temperature to 270 ℃ at a maximum rate; hold for 10 minutes. The operating conditions are as follows: injector temperature, 270 ℃; transmission line temperature, 270 ℃; carrier gas He, flow rate 1mL/min; the injection volume was 1.5mL, no split mode, 40 seconds no split period. Mass spectrometers are multi-ion monitoring or high sensitivity full scans. Provided that the selected ions with m/z 257 (internal standard), 453, 291, 289, 275 and 253 (CPD) monitor positron ionization or a full scan in the range of 100 to 500 amu.

Measurement of 3-CPD-d ₅ Peak areas of (m/z 257) and 3-CPD (m/z 253) derivatives. Calculation of peak area of 3-CPD (m/z 253) derivative and 3-CPD-d ₅ Ratio of peak areas of (m/z 257) derivatives. Calibration plots were constructed for the standards by plotting the peak area ratio of 3-CPD versus weight (micrograms) in each vial. The slope of the calibration line is calculated.

Wherein MCPD = molecular CPD; peak area of a=3-CPD derivative; a' =3-CPD-d ₅ Peak area of the derivative; and c=slope of the calibration line. DCP (which has different retention time peaks and molecular weights on the mass spectrometer) was analyzed using the same sample and standard preparation and analysis techniques.

If CPD or DCP is detected without PAE addition at the wet end of the paper machine, the removal of the Yankee layer from the two layers of the two-layer tissue, napkin or facial tissue product is determined by using a tape layer purity test to determine if these chemicals are from the Yankee coating. Care must be taken to ensure that the surface contact of the yankee surface is that removed by the tape. Some tissue products may be reverse laminated, with the yankee side disposed therein, or with the yankee side laminated. After removal of the yankee layer, the samples were subjected to the test methods described above.

The DCP, CDP and PAE were measured for commercially available tissue samples. The results are shown in table 1 in fig. 9.

Method for testing GPAM/APAM compound content in product

The content of GPAM/APAM complex in the final product was determined using the following test method:

1. the samples were weighed and recorded (paper towel (tolil) 3-4 sheets, paper towel (tissue) 6-7 sheets)

2. The sample was placed in a Soxhlet extractor.

3. About half of the DI water was added to a 250ml flat bottom flask (VWR catalog number 89000-330).

4. The Soxhlet extractor was placed in the neck of a flat bottom flask.

5. The assembled unit was attached to the bottom of the hot water condenser, thus placing the flat bottom flask on the hot plate.

6. The assembled unit is wrapped with two insulating cloths.

7. The hotplate was adjusted to 400 ℃.

8. The condenser is turned on with cold water until you see the water flowing through the hose connected to the condenser and out the overflow tube in the sink. The flow should be stable but not high.

9. Extraction was carried out overnight.

10. The next day the hot plate is turned off and the insulating cloth is removed. The assembled unit is allowed to cool until contact is made.

11. The assembled unit is removed from the condenser. With the assembled units still connected together, the Soxhlet extractor was rinsed with DI water in the DI water bottle. This is to ensure that all the water used in the extraction process flows to the flat bottom flask.

12. The Soxhlet extractor was separated from the flat-bottomed flask, ensuring that any residue in the extractor was able to drain into the flat-bottomed flask.

13. A 250ml beaker was weighed and its weight recorded. And then to a hood (hood).

14. The contents of the flat bottom flask were poured into a beaker.

15. The beaker was placed on a hot plate set to 150 ℃ and the water was evaporated.

16. Once all the water had evaporated, the beaker was cooled to room temperature by closing the hot plate with only the extract remaining in the beaker.

17. The beaker + extract was weighed and recorded.

18. The beaker weight was subtracted from the beaker + extract weight to determine the extract weight. Finally, the weight of the extract is divided by the weight of the original sample and multiplied by 100 to obtain the percentage of the extract. (see table below)

Examples

For the following examples, UHMW GPAM copolymer (Hercobond ^TM Plus 555 dry strength additive), produced by Solenis according to the methods described in U.S. patent No. 7875676B2 and U.S. patent No. 9879381B2 (the contents of which are incorporated herein by reference in their entirety), and transported to the manufacturing site at a solids content of 2% to prevent chemical crosslinking. In order to reduce transportation costs and maintain maximum chemical efficiency, UHMW GPAM is preferably produced on site.

Example 1

Tissues were made using through-air drying on a wet-laid facility with a three-layer headbox. A TAD fabric design was used, named AJ469, supplied by Asten Johnson (4399 Corporate Road,Charleston,SC 29405 USA telephone: + 1.843.747.7800). The flow per layer of the headbox was about 33% of the total sheet. Three layers of finished tissue from top to bottom are labeled as air layer, core layer and dry layer. The air layer is the outer layer placed on the TAD fabric, the drying layer is the outer layer closest to the yankee surface, and the core layer is the central portion of the towel. The towel was produced in all three layers from 75% NBSK (Peare River NBSK, from Mercer, suite 1120, 700West Pender Street Vancouver,BC V6C 1G8 Canada) and 25% eucalyptus (Cenibra pulp, from Itochu International 1251 Avenue of The Americas,New York,NY 10020, telephone: +1-212-818-8244). High cationic HMW GPAM copolymer (hercobb ond ^TM Plus 555 dry strength additive, available from Solenis 2475 Pinnacle Drive,Wilmington,DE 19803 USA phone: +1-866-337-1533) at 11.0 kg/metric ton (dry basis) and HMW APAM (Hercobond ^TM 2800 dry strength additive, available from Solenis) was added to each of the three layers at 3.75 kg/metric ton to create wet strength. NBSK was refined separately on a cone refiner using 70 kwh/metric ton prior to blending into the layer. The speed of Yang Keshi and TAD sections was 1200m/min, running 5% slower than the forming section. The running speed of the spool segments was an additional 3% faster than Yang Keshi. The tissue was then laminated together using the DEKO process described herein using a steel embossing roll with the pattern shown in fig. 1 and a 7% polyvinyl alcohol-based adhesive heated to 120 degrees fahrenheit. A rolled bi-layer product was produced with 156 sheets each having a length of 6.0 inches and a width of 11 inches and a roll having a diameter of 148 mm. The double-layer tissue product has the following product characteristics: basis weight 43.3g/m ² Thickness 0.749mm, MD stretch 497N/m, CD stretch 480N/m, ball burst 1105 g force, MD elongation (stretch) 18.5%, CD elongation (stretch) 11.8%, CD wet stretch 117.2N/m, absorbency 13.25g/g, TSA hand softness 46.2, TS7 of 24.7, TS750 of 36.4. No PAE resin was used in this example.

Comparative example 1

Tissues were made using through-air drying on a wet-laid facility with a three-layer headbox. A TAD fabric design was used, named AJ469, supplied by Asten Johnson (4399 Corporate Road,Charleston,SC 29405 USA telephone: + 1.843.747.7800). The flow per layer of the headbox was about 33% of the total sheet. Three layers of finished tissue from top to bottom are labeled as air layer, core layer and dry layer. The air layer is the outer layer placed on the TAD fabric, the drying layer is the outer layer closest to the yankee surface, and the core layer is the central portion of the towel. The towel was made up of 75% NBSK (from Peare River NBSK, available from Mercer, suite 1120, 700West Pender Street Vancouver,BC V6C 1G8 Canada) and 25% eucalyptus (Cenibra pulp, available from Itochu International 1251 Avenue of The Americas,New York,NY 10020, telephone: +1-212-818-8244) in all three layersAnd (3) production. Polyamine-polyamide-epichlorohydrin resin (Kymene ^TM 1500LV wet strength resin, available from Solenis 2475 Pinnacle Drive,Wilmington,DE 19803USA telephone: +1-866-337-1533) at 9.0 kg/metric ton (dry basis) and high molecular weight anionic polyacrylamide (Hercobond ^TM 2800 dry strength additive, available from Solenis) was added to each of the three layers at 3.75 kg/metric ton (dry basis) to create wet strength. NBSK was refined separately on a cone refiner using 70 kwh/metric ton prior to blending into the layer. The speed of Yang Keshi and TAD sections was 1200m/min, running 5% slower than the forming section. The running speed of the spool segments was an additional 3% faster than Yang Keshi. The tissue was then laminated together using the DEKO process described herein using a steel embossing roll with the pattern shown in fig. 1 and a 7% polyvinyl alcohol-based adhesive heated to 120 degrees fahrenheit. A rolled bi-layer product was produced with 143 sheets each having a length of 6.0 inches and a width of 11 inches and a roll having a diameter of 148 mm. The double-layer tissue product has the following product characteristics: basis weight 40.0g/m ² Thickness 0.806 mm, MD stretch 334N/m, CD stretch 343N/m, ball burst 827 grams force, MD elongation 18.1%, CD elongation 11.1%, CD wet stretch 99.8N/m, absorbency 15.8g/g, TSA hand softness 47.3, TS7 of 23.1, TS750 of 37.1. The measured concentration of CPD in the product was 900ppb, while the measured concentration of DCP was less than 50ppb. The testing method comprises the following steps: LFMB paragraph 64, method B80.56-2-2002-09, uses GCMS. The aqueous extract was prepared according to DIN EN 645:1994-01, 10g of paper per 250ml of cold water. ISEGA (Zeppelinstra βe3, 63741 Ascheffenburg, germany) is the supplier for the tests. The PAE content was 0.165%. No machine white water or furnish is reused or recycled.

Example 2

Tissues were made using through-air drying on a wet-laid facility with a three-layer headbox. A TAD fabric design was used, named AJ469, supplied by Asten Johnson (4399 Corporate Road,Charleston,SC 29405 USA telephone: + 1.843.747.7800). The flow per layer of the headbox was about 33% of the total sheet. Three layers of finished tissue from top to bottom are labeled as air layer, core layer and dry layer. The air layer is the outer layer placed on the TAD fabric,the drying layer is the outer layer closest to the yankee surface and the core layer is the central part of the towel. The towel was produced in all three layers from 75% NBSK (Grand Prairie NBSK, from International Paper,6400 Poplar Ave,Memphis,TN 38197. Telephone: 1-901-419-6500) and 25% eucalyptus (Cenibra pulp, from Itochu International 1251 Avenue of the Americas,New York,NY 10020, telephone: +l-212-818-8244). High cationic HMW GPAM copolymer (Hercobond ^TM Plus 555 dry strength additive, available from Solenis 2475 Pinnacle Drive,Wilmington,DE 19803 USA phone: +1-866-337-1533) at 9.0 kg/metric ton (dry basis) and HMW APAM (Hercobond ^TM 2800 dry strength additive, available from Solenis) was added to each of the three layers at 5.0 kg/metric ton (dry basis) to create wet strength. In addition, 1.5 kg/metric ton (dry basis) of a polyvinylamine retention aid (Hercobond ^TM 6950 dry strength additive from Solenis). The NBSK was refined separately on a cone refiner using 60 kwh/metric ton prior to blending into the layer. The speed of Yang Keshi and TAD sections was 1200m/min, 6% slower than the forming section. The running speed of the spool segments was an additional 3% faster than Yang Keshi. The tissue was then laminated together using the DEKO process described herein using a steel embossing roll with the pattern shown in fig. 1 and 7% polyvinyl alcohol-based adhesive heated to 120 degrees fahrenheit. A rolled bi-layer product was produced with 164 sheets each having a length of 6.0 inches and a width of 11 inches and a roll having a diameter of 148 mm. The double-layer tissue product has the following product characteristics: basis weight 40.7g/m ² Thickness 0.726mm, MD stretch 476N/m, CD stretch 421N/m, ball burst 1055 gram force, MD elongation 19.5%, CD elongation 11.4%, CD wet stretch 120.9N/m, absorbency 12.58g/g, TSA hand softness 44.6, TS7 of 24.3, TS750 of 47.3, 103 revolutions wet scrub, 504 micron/2 layer wet thickness, 342gf wet ball burst. The measured concentration of CPD in the product is less than 50ppb, and the measured concentration of DCP is less than 50ppb, test method: LFMB paragraph 64, method B80.56-2-2002-09, uses GCMS. The aqueous extract was prepared according to DIN EN 645:1994-01, 10g of paper per 250ml of cold water. ISEGA (Zeppelinstra βe3, 63741 Ascheffenburg, germany) is the supplier for the tests. Paper machine The white water or furnish is reused or recycled. The PAE content was 0.02%. No adipic acid PAE was found in this sample, only a small amount of glutaric acid PAE was detected, which is known to be added to the Yang Keshi coating.

Example 3

Tissues were made using through-air drying on a wet-laid facility with a three-layer headbox. A TAD fabric design was used, named AJ469, supplied by Asten Johnson (4399 Corporate Road,Charleston,SC 29405 USA telephone: + 1.843.747.7800). The flow per layer of the headbox was about 33% of the total sheet. Three layers of finished tissue from top to bottom are labeled as air layer, core layer and dry layer. The air layer is the outer layer placed on the TAD fabric, the drying layer is the outer layer closest to the yankee surface, and the core layer is the central portion of the towel. The towel was produced in all three layers from 75% NBSK (Grand Prairie NBSK, from International Paper,6400 Poplar Ave,Memphis,TN 38197. Telephone: 1-901-419-6500) and 25% eucalyptus (Cenibra pulp, from Itochu International 1251 Avenue of the Americas,New York,NY 10020, telephone: +l-212-818-8244). High cationic HMW GPAM copolymer (Hercobond ^TM Plus 555 dry strength additive, available from Solenis 2475 Pinnacle Drive,Wilmington,DE 19803 USA phone: +1-866-337-1533) at 11.0 kg/metric ton (dry basis) and HMW APAM (Hercobond ^TM 2800 dry strength additive, available from Solenis) was added to each of the three layers at 5.0 kg/metric ton (dry basis) to create wet strength. In addition, 1.5 kg/metric ton (dry basis) of a polyvinylamine retention aid (Hercobond ^TM 6950 dry strength additive from Solenis). The NBSK was refined separately on a cone refiner using 60 kwh/metric ton prior to blending into the layer. The speed of Yang Keshi and TAD sections was 1200m/min, running 5% slower than the forming section. The running speed of the spool segments was an additional 3% faster than Yang Keshi. The tissue was then laminated together using the DEKO process described herein using a steel embossing roll with the pattern shown in fig. 1 and 7% polyvinyl alcohol-based adhesive heated to 120 degrees fahrenheit. Rolled bi-layer product was produced with 162 sheets each having a length of 6.0 inches and a width of 148mm diameter rolls11 inches. The double-layer tissue product has the following product characteristics: basis weight 41.6g/m ² Thickness 0.728mm, MD stretch 538N/m, CD stretch 490N/m, ball burst 1108 g force, MD elongation 20.4%, CD elongation 12.7%, CD wet stretch 125.2N/m, absorbency 12.58g/g, TSA hand softness 42.8, TS7 of 25.2, TS750 of 54.0, wet scrub 114 turn, 533 microns/2 wet thickness and 405gf wet ball burst. No PAE resin was used in this example.

Example 4

Tissues were made using through-air drying on a wet-laid facility with a three-layer headbox. A TAD fabric design was used, named AJ469, supplied by Asten Johnson (4399 Corporate Road,Charleston,SC 29405 USA telephone: + 1.843.747.7800). The flow per layer of the headbox was about 33% of the total sheet. Three layers of finished tissue from top to bottom are labeled as air layer, core layer and dry layer. The air layer is the outer layer placed on the TAD fabric, the drying layer is the outer layer closest to the yankee surface, and the core layer is the central portion of the towel. The towel was produced in all three layers from 75% NBSK (Grand Prairie NBSK, from International Paper,6400 Poplar Ave,Memphis,TN 38197 telephone: 1-901-419-6500) and 25% eucalyptus (Cenibra pulp, from Itochu International 1251 Avenue of the Americas,New York,NY 10020, telephone: +l-212-818-8244). High cationic HMW GPAM copolymer (Hercobond ^TM Plus 555 dry strength additive, available from Solenis 2475 Pinnacle Drive,Wilmington,DE 19803 USA phone: +1-866-337-1533) at 4.5 kg/metric ton (dry basis), polyamine-polyamide-epichlorohydrin resin (Kymene ^TM 1500LV wet strength resin, available from Solenis 2475 Pinnacle Drive,Wilmington,DE 19803 USA telephone: +1-866-337-1533) at 2.5 kg/metric ton (dry basis) and high molecular weight anionic polyacrylamide (Hercobond ^TM 2800 dry strength additive, available from Solenis) was added to each of the three layers at 5.0 kg/metric ton (dry basis) to create wet strength. In addition, 1.5 kg/metric ton (dry basis) of a polyvinylamine retention aid (Hercobond ^TM 6950 dry strength additive from Solenis). NBSK is carried on a cone refiner prior to blending into the layer60 kwh/metric ton of individual refining was used. The speed of Yang Keshi and TAD sections was 1200m/min, 6% slower than the forming section. The running speed of the spool segments was an additional 3% faster than Yang Keshi. The tissue was then laminated together using the DEKO process described herein using a steel embossing roll with the pattern shown in fig. 1 and a 7% polyvinyl alcohol-based adhesive heated to 120 degrees fahrenheit. A rolled bi-layer product was produced with 152 sheets each having a length of 6.0 inches and a width of 11 inches and a roll having a diameter of 148 mm. The double-layer tissue product has the following product characteristics: basis weight 40.6g/m ² Thickness 0.754mm, MD stretch 417N/m, CD stretch 412N/m, ball burst 1058 grams force, MD elongation 18.5%, CD elongation 11.9%, CD wet stretch 112.2N/m, absorbency 14.33g/g, TSA hand softness 45.4, TS7 of 23.7, TS750 of 45.8, wet scrub 95 turns, wet thickness 534 microns/2 layer, wet ball burst 334gf. The measured concentration of CPD in the product was 500ppb, while the measured concentration of DCP was 53ppb, test method: LFMB paragraph 64, method B80.56-2002-09, by GCMS. The aqueous extract was prepared according to DIN EN 645:1994-01, 10g of paper per 250ml of cold water. ISEGA (Zeppelinstra βe3, 63741 Ascheffenburg, germany) is the supplier for the tests. PAE was measured to be 0.054%. The hot water extraction of the compound from the two layers yielded 0.036g with an extract percentage of 0.55%. No machine white water or furnish is reused or recycled.

Comparative example 2

Tissues were made using through-air drying on a wet-laid facility with a three-layer headbox. A TAD fabric design was used, named AJ469, supplied by Asten Johnson (4399 Corporate Road,Charleston,SC 29405 USA telephone: + 1.843.747.7800). The flow per layer of the headbox was about 33% of the total sheet. Three layers of finished tissue from top to bottom are labeled as air layer, core layer and dry layer. The air layer is the outer layer placed on the TAD fabric, the drying layer is the outer layer closest to the yankee surface, and the core layer is the central portion of the towel. The towel was made from 75% NBSK (Grand Prairie NBSK, purchased from International Paper,6400 Poplar Ave,Memphis,TN 38197 telephone: 1-901-419-6500) and 25% eucalyptus stock (Cenibra pulp, purchased from Itochu International 1251 Avenue of the Americas,new York, NY 10020, phone: +l-212-818-8244) are produced in all three layers. Polyamine-polyamide-epichlorohydrin resin (Kymene ^TM 1500LV wet strength resin, available from Solenis 2475Pinnacle Drive,Wilmington,DE 19803USA telephone: +1-866-337-1533 ^TM 2800 dry strength additive, available from Solenis) at 9.0 kg/metric ton (dry basis) and HMW APAM (Hercobond ^TM 2800 dry strength additive, available from Solenis) was added to each of the three layers at 5.0 kg/metric ton (dry basis) to create wet strength. In addition, 1.5 kg/metric ton (dry basis) of a polyvinylamine retention aid (Hercobond ^TM 6950 dry strength additive from Solenis). The NBSK was refined separately on a cone refiner using 60 kwh/metric ton prior to blending into the layer. The speed of Yang Keshi and TAD sections was 1200m/min, 6% slower than the forming section. The running speed of the spool segments was an additional 3% faster than Yang Keshi. The tissue was then laminated together using the DEKO process described herein using a steel embossing roll with the pattern shown in fig. 1 and a 7% polyvinyl alcohol-based adhesive heated to 120 degrees fahrenheit. A rolled bi-layer product was produced with 146 sheets each having a length of 6.0 inches and a width of 11 inches and a roll having a diameter of 148 mm. The double-layer tissue product has the following product characteristics: basis weight 41.4g/m ² Thickness 0.79mm, MD stretch 436N/m, CD stretch 360N/m, ball burst 1031 gram force, MD elongation 18.0%, CD elongation 11.2%, CD wet stretch 105.2N/m, absorbency 14.1g/g, TSA hand softness 49.0, TS7 of 22.8, TS750 of 42.0, wet scrub 95 revolutions, wet burst 310.7 gram force, wet thickness 600 microns/2 layer. The measured concentration of CPD in the product was 2375ppb, while the measured concentration of DCP was 190ppb, test method: LFMB paragraph 64, method B80.56-2002-09, by GCMS. The aqueous extract was prepared according to DIN EN 645:1994-01, 10g of paper per 250ml of cold water. ISEGA (Zeppelinstra βe3, 63741 Ascheffenburg, germany) is the supplier for the tests. No machine white water or furnish is reused or recycled.

Comparative example 3

Tissues were made using through-air drying on a wet-laid facility with a three-layer headbox. The TAD fabric development design was developed using the method of U.S. patent No. 10815620The contents of which are hereby incorporated by reference in their entirety. TAD fabrics are laminated composite fabrics having a web contacting layer made of an extruded thermoplastic polyurethane web with 30 elements/inch in the machine direction and 5 elements/inch in the cross machine direction. The longitudinal element has a width of about 0.26mm and the transverse element has a width of 0.6 mm. The distance between MD elements was about 0.60mm and the spacing between CD elements was 5.5mm. The total bag depth is equal to the web thickness, equal to 0.4mm. The depth from the top surface of the web to the top surface of the CD elements was 0.25mm. The support layer had rectangular MD yarns (or filaments) with a cross section of 0.27 by 0.22mm at 56 yarns/inch and CD yarns with a thickness of 0.35mm at 41 yarns/inch. The weave pattern of the base layer is 5 shed, 1MD yarn over 4 CD yarns, then under 1 CD yarn, and then repeated. The material of the base fabric yarn was 100% pet. The composite fabric has an air permeability of about 450 cfm. The flow per layer of the headbox was about 33% of the total sheet. Three layers of finished tissue from top to bottom are labeled as air layer, core layer and dry layer. The air layer is the outer layer placed on the TAD fabric, the drying layer is the outer layer closest to the yankee surface, and the core layer is the central portion of the towel. The towel was produced in all three layers using 50% NBSK (Grand Prairie NBSK, from International Paper,6400 Poplar Ave,Memphis,TN 38197 telephone: 1-901-419-6500) and 50% eucalyptus (Cenibra pulp, from Itochu International 1251Avenue of the Americas,New York,NY 10020, telephone: +l-212-818-8244). "G3" polyamine-polyamide-epichlorohydrin resin (Kymene ^TM GHP20 wet strength resin, available from Solenis 2475 Pinnacle Drive,Wilmington,DE 19803 USA phone: +1-866-337-1533) at 9.0 kg/metric ton (dry basis) and HMW APAM (Hercobond ^TM 2800 dry strength additive, available from Solenis) was added to each of the three layers at 5.0 kg/metric ton (dry basis) to create wet strength. In addition, 1.5 kg/metric ton (dry basis) of a polyvinylamine retention aid (Hercobond ^TM 6950 dry strength additive from Solenis). The NBSK was refined separately prior to blending into the layer using 71 kwh/metric ton on a cone refiner. BEK was run on a conical refiner with 20 kWh +.Metric tons are refined separately. Yang Keshi and TAD sections were 1000m/min, 3% slower than the forming section. The running speed of the spool segments was another 10% slower than Yang Keshi. The tissue was then laminated together using the DEKO process described herein using a steel embossing roll with the pattern shown in fig. 1 and a 7% polyvinyl alcohol-based adhesive heated to 120 degrees fahrenheit. A rolled bi-layer product was produced with 228 sheets each having a length of 6.0 inches and a width of 11 inches and a roll having a diameter of 148 mm. The double-layer tissue product has the following product characteristics: basis weight 42g/m ² Thickness 0.508mm, MD stretch 407N/m, CD stretch 486N/m, ball burst 944 g force, MD elongation 20.2%, CD elongation 11.0%, CD wet stretch 129.9N/m, absorbency 11.49g/g, TSA hand softness 51.5, TS7 of 21.7, TS750 of 38.7, wet scrub 49 turns, wet burst 336.6 g force, wet thickness 455.7 microns/2 layer. The measured concentration of CPD in the product was 148ppb, while the measured concentration of DCP was less than 50ppb, test method: LFMB paragraph 64, method B80.56-2002-09, uses GCMS. The aqueous extract was prepared according to DIN EN 645:1994-01, 10 g of paper per 250 ml of cold water. ISEGA (Zeppelinstra βe3, 63741 Ascheffenburg, germany) is the supplier for the tests. The PAE percentage was 0.12 wt%. No machine white water or furnish is reused or recycled.

Comparative example 5

Tissues were made using through-air drying on a wet-laid facility with a three-layer headbox. TAD fabric design was used with round weft yarn (0.65 mm) named AJ469 provided by Asten Johnson (4399 Corporate Road,Charleston,SC 29405USA phone: + 1.843.747.7800). The flow per layer of the headbox was about 33% of the total sheet. Three layers of finished tissue from top to bottom are labeled as air layer, core layer and dry layer. The air layer is the outer layer placed on the TAD fabric, the drying layer is the outer layer closest to the yankee surface, and the core layer is the central portion of the towel. The towel was prepared in full using 70% NBSK (Grand Prairie NBSK, from International Paper,6400 Poplar Ave,Memphis,TN 38197 telephone: 1-901-419-6500) and 30% eucalyptus (Cenibra pulp, from Itochu International 1251Avenue of the Americas,New York,NY 10020, telephone: +l-212-818-8244) And (5) producing three layers. GPAM copolymer Fennerez 3000 from Kemira (Energiakatu 4P.O.Box 330 00101 Helsinki,Finland telephone +358 10 8611 fax +358 10 862 1119) was added to each of the three layers at 2.0 kg/metric ton (dry basis) and APAM (Fennobond 85, available from Kemira) at 2.0 kg/metric ton (dry basis) to produce wet strength. For this embodiment, an exemplary polymeric aldehyde-functionalized polymer may be glyoxalated polyacrylamide, such as cationic glyoxalated polyacrylamide or APAM, as described in U.S. patent nos. 3556932, 3556933, 4605702, 7829834 and U.S. patent application No. 2008/0308242, each of which is incorporated herein by reference. Such compounds include FENNOBOND from Kemira Chemicals of Helsinki, finland ^TM Branded polymers. NBSK was refined separately on a cone refiner using 60 kwh/metric ton prior to blending into each layer. The yankee and TAD stages were 1350m/min at a 12% slower speed than the forming stage. In addition, the speed of the spool section is the same as the yankee. The tissue was then laminated together using the DEKO process described herein using a steel embossing roll with the pattern shown in fig. 1 and a 7% polyvinyl alcohol-based adhesive heated to 120 degrees fahrenheit. The rolled 2-ply product was produced with 148 sheets each having a length of 6.0 inches and a width of 11 inches and a roll having a diameter of 148 mm. The double-layer tissue product has the following product characteristics: basis weight 38.4g/m ² Thickness 0.778mm, MD stretch 280N/m, CD stretch 302N/m, ball burst 708 g force, MD elongation 14.6%, CD elongation 8.6%, CD wet stretch 57.3N/m, absorbency 14.15g/g, TSA hand softness 46.8, TS7 of 22.5, TS750 of 52.4, D value of 2.4, wet scrub 35 revolutions, wet thickness 542 μm/2 layer, wet ball burst 140gf. No PAE resin was added.

Example 5

Tissues were made using through-air drying on a wet-laid facility with a three-layer headbox. TAD fabric design using round weft yarn, named AJ469, provided by Asten Johnson (4399 Corporate Road,Charleston,SC 29405 USA phone: + 1.843.747.7800). The flow per layer of the headbox was about 33% of the total sheet. Three layers of finished tissue from top to bottom are labeled as air layer, core layer and dry layer. Air layerIs the outer layer placed on the TAD fabric, the dryer layer is the outer layer closest to the yankee dryer surface, and the core layer is the central portion of the towel. The towel was produced in all three layers using 70% NBSK (Grand Prairie NBSK, from International Paper,6400Poplar Ave,Memphis,TN 38197 telephone: 1-901-419-6500) and 30% eucalyptus (Cenibra pulp, from Itochu International 1251Avenue of the Americas,New York,NY 10020, telephone: +l-212-818-8244). High cationic HMW GPAM copolymer (Hercobond ^TM Plus 555 dry strength additive, available from Solenis 2475Pinnacle Drive,Wilmington,DE 19803USA phone: +1-866-337-1533) at 6.3 kg/metric ton (dry basis) and HMW APAM (Hercobond ^TM 2800 dry strength additives, available from Solenis) were added to each of the three layers at 2.1 kg/metric ton (dry basis) to create wet strength. In addition, 0.3 kg/metric ton (dry basis) of a polyvinylamine retention aid (Hercobond ^TM 6950 dry strength additive from Solenis). The NBSK was refined separately on a cone refiner using 60 kwh/metric ton prior to blending into the layer. Yang Keshi and TAD stages are 1350m/min operated at a speed 12% slower than the forming stage. The running speed of the spool segments was 2% slower than Yang Keshi. The tissue was then laminated together using the DEKO process described herein using a steel embossing roll with the pattern shown in fig. 1 and a 7% polyvinyl alcohol-based adhesive heated to 120 degrees fahrenheit. A rolled bi-layer product was produced with 143 sheets each having a length of 6.0 inches and a width of 11 inches and a roll having a diameter of 148 mm. The double-layer tissue product has the following product characteristics: basis weight 40.8g/m ² Thickness 0.840mm, MD stretch 398N/m, CD stretch 445N/m, ball burst 1042 g force, MD elongation 18.0%, CD elongation 9.3%, CD wet stretch 105N/m, absorbency 15.16g/g, TSA hand softness 41.9, TS7 of 27.3, TS750 of 54.8, D value 2.2, wet scrub 85 revolutions, wet thickness 594 microns/2 layer, wet ball burst 266gf. The measured concentration of CPD in the product is less than 50ppb, and the measured concentration of DCP is less than 50ppb, test method: LFMB paragraph 64, method B80.56-2002-09, by GCMS. The aqueous extract was prepared according to DIN EN 645:1994-01, 10g of paper per 250ml of cold water. ISEGA (Zeppelinstra. Beta. E3, 63741 Ascheffenburg, germany) Country) is the provider that performed the test. No machine white water or furnish is reused or recycled. The PAE content was less than 0.02% and no adipic acid PAE was detected in the sample. Only glutaric acid PAE was detected, which is known to be added to yankee coatings. Hot water extraction of 0.038 g and 0.57% of the complex was obtained from all three-layer products.

Example 6

Tissues were made using through-air drying on a wet-laid facility with a three-layer headbox. Laminated composite fabrics with polyurethane webs having MD of 16 strands per inch by CD of 14 strands per inch as described in us patent 10815620 were used. The flow per layer of the headbox was about 33% of the total sheet. Three layers of finished tissue from top to bottom are labeled as air layer, core layer and dry layer. The air layer is the outer layer placed on the TAD fabric, the drying layer is the outer layer closest to the yankee surface, and the core layer is the central portion of the towel. The towel was produced in all three layers using 70% NBSK (Grand Prairie NBSK, from International Paper,6400Poplar Ave,Memphis,TN 38197. Telephone: 1-901-419-6500) and 30% eucalyptus (Cenibra pulp, from Itochu International 1251 Avenue of the Americas,New York,NY 10020, telephone: +l-212-818-8244). High cationic HMW GPAM copolymer (Hercobond ^TM Plus 555 dry strength additive, available from Solenis 2475Pinnacle Drive,Wilmington,DE 19803USA phone: +1-866-337-1533) at 9.0 kg/metric ton (dry basis) and HMW APAM (Hercobond ^TM 2800 dry strength additive, available from Solenis) was added to each of the three layers at 5.0 kg/metric ton (dry basis) to create wet strength. In addition, 1.5 kg/metric ton (dry basis) of a polyvinylamine retention aid (Hercobond ^TM 6950 dry strength additive from Solenis). NBSK was refined separately on a cone refiner using 100 kwh/metric ton prior to blending into the layer. Yang Keshi and TAD sections are run at a speed of 1000m/min 6% slower than the former section. The running speed of the spool segments was another 14% slower than Yang Keshi. The tissue was then laminated together using the DEKO process described herein using a steel embossing roll with the pattern shown in fig. 1 and 7% polyvinyl alcohol based adhesive heated to 120 degrees fahrenheit. By 134 sheetsThe sheets and a roll of 148mm diameter produced a rolled bi-layer product, each sheet having a length of 6.0 inches and a width of 11 inches. The double-layer tissue product has the following product characteristics: basis weight 43.2g/m ² Thickness 0.328 mm, MD stretch 407N/m, CD stretch 441N/m, ball burst 1149 gram force, MD elongation 25.4%, CD elongation 13.1%, CD wet stretch 125.6N/m, absorbency 17.60g/g, TSA handle softness 38.3, TS7 of 33.9, TS750 of 33.2, D value 2.2, wet scrub 110 revolutions, wet thickness 610 microns/2 layer. Wet bulb burst was not measurable. The measured concentration of CPD in the product is less than 50ppb, and the measured concentration of DCP is less than 50ppb, test method: LFMB paragraph 64, method B80.56-2002-09, by GCMS. The aqueous extract was prepared according to DIN EN 645:1994-01, 10g of paper per 250ml of cold water. ISEGA (Zeppelinstra βe3, 63741 Ascheffenburg, germany) is the supplier for the tests. No machine white water or furnish is reused or recycled.

As is apparent from the above examples and comparative examples, the method according to the exemplary embodiments of the present invention results in roll retail tissue with very low DCP and MCPD, as well as superior tissue properties (bulk), absorbency, MD/CD dry strength and CD wet strength) with very low doses of PAE. By way of background, G2 or G3 PAE, which is the PAE just distilled (i.e., removal of chlorine material prior to use in a mill), may be used to obtain a level of wet strength. However, distilled PAE produces chlorine compounds and has lower reactivity per molecule and lower wet strength characteristics. In addition, more distilled PAE is required to obtain high levels of wet strength, which is detrimental to absorbency and environment and expensive. Overall, the use of G2/G3-PAE results in a tissue product with low strength, low absorbency and low bulk at a higher cost.

As shown in comparative example 5, if the molecular weight of the GPAM/APAM composite is too low or the radius of gyration (ROG) of the composite (explained further below) is not optimal, the performance required for a tissue product may not be obtained using the GPAM/APAM composite. In contrast, according to an exemplary embodiment of the present invention, a very high molecular weight composite is used to form a "web" around the pulp web, thereby holding the web together. Therefore, GPAM is preferably produced at 2% solids on the milling site. In contrast, most GPAM has a solids content of greater than 5% or nearly 10%.

Without being bound by theory, one important aspect of the present invention relates to the use of high MW GPAM/APAM complexes that retain anions, rather than to conventional techniques that use cationic complexes. The use of anionic retaining GPAM/APAM complexes is believed to create more ionic or covalent bonds between the complex and the pulp fibers. This is contrary to conventional wisdom (cationic complexes need to bond to anionic fibers (e.g., all untreated pulp fibers)). Also, without being bound by theory, it is believed that charge is not the dominant factor, as is or more important the number of connections in the network. The cationic GPAM/APAM complex indicates that the GPAM charge occupies the APAM. The APAM polymer is consumed and may not expand to its maximum size. The use of anionic GPAM/APAM complexes results in larger anionic sizes, which can be expressed as ROG of the polymer. A larger ROG will produce a larger net with the same number of molecules.

Without PVAM retention aid, the large anionic GPAM/APAM complex may not be maintained at sufficient levels. PVAM has a very high cationic character. This high charge forces the GPAM/APAM complex to bond with pulp fibers having uniformly spaced negative charges.

While specific embodiments of the invention have been described in detail in the foregoing description, it will be appreciated by those skilled in the art that numerous specific details may be set forth herein without departing from the spirit and scope of the invention.

Claims

1. A retail roll towel product comprising:

a bi-layer cellulosic sheet or web having a transverse wet strength of 80N/m to 200N/m and a bi-layer thickness of 600 microns to 1500 microns, wherein the retail tissue product contains 0 to 550ppb chloropropanediol and 0 to 0.09 weight percent polyaminoamide-epihalohydrin.

2. According to claim 1Wherein the transverse wet strength is from 80N/m to 150N/m, the bilayer thickness is from 700 micrometers to 1300 micrometers, and the tissue product has 38g/m ² To 50g/m ² Wherein the retail tissue product comprises 50ppb to 550ppb of chloropropanediol and 0.01% to 0.04% by weight of a polyaminoamide-epihalohydrin.

3. A tissue or tissue product comprising:

95 to 99% by weight of cellulosic fibers; and

from 0.25% to 1.5% by weight of an ultra-high molecular weight glyoxalated polyvinylamide adduct and a high molecular weight anionic polyacrylamide complex.

4. A tissue or tissue product comprising:

95 to 99% by weight of cellulosic fibers;

0.25 to 1.5 weight percent of an ultra-high molecular weight glyoxalated polyethylene amide adduct and a high molecular weight anionic polyacrylamide complex; and

0.03 to 0.5% by weight of a polyvinylamine.

5. A method of manufacturing an absorbent structure, comprising:

forming a feedstock mixture comprising cellulosic fibers, a high molecular weight anionic polyacrylamide, and an ultra high molecular weight glyoxalated polyvinylamide adduct; and

the raw material mixture is at least partially dried using a wet-laid process to form a web, wherein no polyaminoamide-epihalohydrin is added to the raw material mixture.

6. The process of claim 5, wherein the absorption structure has a dichloropropanol concentration of less than 50ppb and the absorption structure has a chloropropanol concentration of less than 300ppb.

7. The method of claim 6, wherein the feed mixture further comprises:

an additive selected from lignin, laccase polymerized lignin, hemicellulose, polymerized hemicellulose, hemp stalk core, pectin, hydroxyethyl cellulose, carboxymethyl cellulose, guar gum, soy protein, chitin, polyvinylamine, polyethyleneimine, and combinations thereof.

8. An absorbent product comprising cellulosic fibres comprising dichloropropanol at a concentration of less than 50ppb and chloropropanol at a concentration of less than 300ppb and having a transverse wet strength of from 80N/m to 200N/m, wherein the product is free of polyaminoamide-epihalohydrin, measured using the "adipic acid test".

9. The absorbent product of claim 8, wherein the product is a through-air dried tissue, napkin, or towel.

10. A tissue product comprising:

a double-layer creped through-air dried retail tissue having a transverse wet strength of 80N/m to 150N/m, a dry thickness of 700 microns to 1200 microns, 50ppb to 400ppb of chloropropanol measured in the paper making up the product, and 30ppb to 200ppb of dichloropropanol measured in the paper,

wherein the polyvinylamine is added to the wet end of a paper machine used to make the tissue product.

11. A tissue product comprising:

a double-layer creped through-air dried retail tissue having a transverse wet strength of 80N/m to 150N/m, a dry thickness of 700 microns to 1200 microns, 50ppb to 300ppb of chloropropanol measured in the paper making up the product, and 5ppb to 50ppb of dichloropropanol measured in the paper,

Wherein no PAE resin is added to the wet end of the paper machine used to make the tissue product.