High strength hydroentangled sheet containing non-wood fibers

Abstract

The present disclosure is generally directed to dry or pre-moistened wiper with high tensile strength characteristics. The sheet products can be made from a combination of non-wood fibers, wood pulp fibers, and regenerated cellulose fibers. In one aspect, the sheet products can be formed through a foam-forming process and hydroentangled.

Description

[0001] HIGH STRENGTH HYDROENTANGLED SHEET CONTAINING NON-WOOD FIBERS

[0002] BACKGROUND

[0003] Domestic and industrial wipers are often used to absorb liquids and pick up debris. In some applications, the wipers are formed into a premoistened wiping product for the purposes of cleaning and / or disinfecting. In the past, many attempts have been made in order to produce non-cloth wiping products made from nonwoven fibers that are designed generally to be used and discarded. Such wipers should possess a good balance of properties, including good physical strength and abrasion resistance, to withstand the tearing, stretching, and abrading forces often applied during use.

[0004] In the past, many nonwoven wipers have been constructed from wood pulp fibers in combination with synthetic thermoplastic fibers, such as polyester fibers. For example, in the past, wood pulp fibers, such as softwood fibers, have been hydroentangled with synthetic thermoplastic fibers in order to produce a resilient wiping product.

[0005] For example, in one embodiment, the wood pulp fibers have been combined with synthetic thermoplastic fibers, such as polyester fibers, polypropylene fibers, and the like for increasing the strength of the web. Synthetic thermoplastic fibers, however, are naturally hydrophobic and have poor absorbency. The wipers also require significant amounts of polymer, particularly fossil-based polymers, for constructing the wipers.

[0006] In an alternative embodiment, wood pulp fibers have been combined and hydroentangled with regenerated cellulose fibers, such as rayon fibers. Regenerated cellulose fibers are formed from wood pulps that have been purified and then spun into fibers. Regenerated cellulose fibers have good absorbency and strength properties and provide softness to the web. Regenerated cellulose fibers, however, have an exorbitant cost and still create environmental concerns.

[0007] In view of the above, a need currently exists for nonwoven webs that can be produced with high strength properties while minimizing the amount of synthetic thermoplastic fibers and regenerated cellulose fibers.

[0008] SUMMARY

[0009] The present disclosure is generally directed to nonwoven webs, particularly hydroentangled nonwoven webs that contain non-wood fibers. The non-wood fibers, for instance, can be longer than wood pulp fibers while having relatively low coarseness properties. The non-wood plant fibers are combined with wood pulp fibers and synthetic cellulose fibers, namely regenerated cellulose staple fibers in producing base sheets having excellent strength properties when either dry or wet. In accordance with the present disclosure, the amount of regenerated cellulose fibers can be maintained at relatively low amounts while still providing desired physical properties.

[0010] For example, in one embodiment, the present disclosure is directed to a sheet product comprising a base sheet having a machine direction and a cross direction. The base sheet comprises non-wood pulp fibers in an amount of greater than about 5% by weight, such as in an amount from about 5% by weight to about 55% by weight, such as in an amount of from about 5% by weight to about 30% by weight.

[0011] The non-wood pulp fibers can have a coarseness of less than about 10 mg / 100 m (1 .0 dTex), such as less than about 8 mg / 100 m (0.8 dTex), such as less than about 6 mg / 100 m (0.6 dTex), such as less than about 5 mg / 100 m (0.5 dTex), and can have an average fiber length of from about 1 .5 mm to about 2.5 mm. In one aspect, the non-wood fibers can be derived from one or more plants of the genus Hesperaloe. The fibers, for instance, can be derived from one or more of the following plants: Hesperaloe funifera, Hesperaloe parviflora, Hesperaloe noctuma, Hesperaloe chiangic, Hesperaloe tenuifolia, Hesperaloe engelmannii, Hesperaloe malacophylla, or mixtures thereof. In one particular aspect, the Hesperaloe fibers comprise Hesperaloe funifera fibers. The non-wood pulp fibers can also be bleached.

[0012] In addition to the non-wood pulp fibers, the base sheet further comprises wood pulp fibers and regenerated cellulose fibers. The regenerated cellulose fibers can comprise staple fibers. In one aspect, the regenerated cellulose fibers can comprise lyocell fibers. In accordance with the present disclosure, the regenerated cellulose fibers are present in an amount no greater than about 40% by weight. For instance, the regenerated cellulose fibers can be present in an amount from about 5% by weight to about 30% by weight, such as in an amount from about 10% by weight to about 20% by weight. In one aspect, the regenerated cellulose fibers can have an average fiber length of from about 4 mm to about 20 mm, such as from about 5 mm to about 15 mm. The regenerated cellulose fibers can have a size of from about 0.7 dtex to about 2 dtex. In one aspect, the regenerated cellulose fibers can be crimped.

[0013] The wood pulp fibers can comprise softwood fibers, hardwood fibers, or combinations thereof In one aspect, the wood pulp fibers comprise softwood fibers, such as Southern softwood kraft fibers or Northern softwood kraft fibers. The wood pulp fibers can be present in the base sheet in an amount of at least about 40% by weight, such as in an amount from about 60% by weight to about 90% by weight. In one aspect, the base sheet is formed through a foam forming process. The base sheet, in one embodiment, can comprise a single ply web that is non-layered. The base sheet can have a basis weight of from about 30 gsm to about 100 gsm, such as from about 55 gsm to about 70 gsm.

[0014] In accordance with the present disclosure, the base sheet can display excellent physical properties. For instance, the base sheet can display a wet tensile strength in the cross direction of greater than about 200 gf, such as greater than about 300 gf, such as greater than about 400 gf, such as greater than about 500 gf, such as greater than about 600 gf (based upon a 3-inch wide sample). The base sheet can display a dry tensile strength in the machine direction of greater than about 800 gf, such as greater than about 1 ,000 gf, such as greater than about 1,500 gf, such as greater than about 2,000 gf. For example, in one particular embodiment, the base sheet can have a basis weight of from about 55 gsm to about 70 gsm and can display a wet tensile strength in the cross direction of greater than about 500 gf, such as greater than about 600 gf, such as greater than about 700 gf, such as greater than about 800 gf, and can display a dry tensile strength in the machine direction of greater than about 2,000 gf, such as greater than about 2,500 gf, such as greater than about 3,000 gf, such as greater than about 3,500 gf.

[0015] In one aspect, the base sheet can be substantially free of synthetic thermoplastic fibers. For instance, the base sheet can contain synthetic thermoplastic fibers in an amount less than about 5% by weight, such as in an amount less than about 2% by weight and, in one embodiment, does not contain any synthetic thermoplastic fibers.

[0016] The sheet product of the present disclosure can be packaged and provided to consumers either in a dry form or in a wet form. For instance, in one embodiment, the sheet product can further comprise a wetting solution for producing a pre-moistened wiper.

[0017] In one aspect, the sheet product can comprise a plurality of individual sheets that are arranged in a stacked arrangement. The sheet product can comprise, for instance, dry industrial wipers, premoistened wipers for general use, medical use, or for applying a disinfectant. Alternatively, the sheet product can be packaged in a spirally wound roll including periodic lines of perforation for accessing an individual sheet.

[0018] The present disclosure is also directed to a method of producing a sheet product. The method includes forming a fibrous suspension. The fibrous suspension contains non-wood pulp fibers, wood pulp fibers, and regenerated cellulose fibers as described above. The fibers are suspended within a foam.

[0019] The fibrous suspension is deposited onto a forming surface to form a base sheet. The base sheet is subjected to a plurality of liquid jets in order to hydroentangle the fibers. The base sheet can then be dried. Optionally, a wetting solution can be incorporated into the base sheet for forming a moist wipe. In one aspect, the non-wood fibers comprise Hesperaloe funifera pulp fibers.

[0020] Other features and aspects of the present disclosure are discussed in greater detail below.

[0021] BRIEF DESCRIPTION OF THE DRAWINGS

[0022] A full and enabling disclosure of the present disclosure is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:

[0023] Figure 1 is a diagram of one embodiment of a process for producing base sheets in accordance with the present disclosure; and

[0024] Figure 2 is a diagram of an enlarged portion of the process illustrated in Figure 1 .

[0025] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.

[0026] DEFINITIONS

[0027] The term "machine direction" as used herein refers to the direction of travel of the forming surface onto which fibers are deposited during formation of a nonwoven web.

[0028] The term "cross-machine direction" as used herein refers to the direction which is perpendicular to the machine direction defined above.

[0029] As used herein, the term “nonwoven web or material" refers to a web having a structure of individual fibers that are interlaid, but not in an identifiable manner as in a knitted or woven fabric. Nonwoven materials include, for example, carded webs, wet-laid webs, airlaid webs, foam-formed webs, and the like.

[0030] As used herein, the term “biomass” generally refers to organic matter derived from a non- woody plant and includes both whole plants and plant organs (i.e., leaves, stems, flowers, roots, etc.).

[0031] As used herein, the term “bagasse” generally refers to biomass that has been subjected to a processing step such as, for example, pressing, milling, compression, or maceration, to remove a portion of the biomass water soluble solids. In certain embodiments, bagasse is prepared by subjecting the biomass to compression and maceration using a plug screw, or other form of compression screw, to extract a portion of the biomass water soluble solids.

[0032] As used herein, the term “pulp” generally refers to a plurality of cellulose fibers that have undergone a pulping process such that the fibers have been individualized and wherein the fibers have an elongate shape in which the apparent length exceeds the apparent width. Pulp fibers can be fibrillated and can have a measurable freeness. As used herein, the term “fines” generally refers to fibrous water insoluble cellulosic material having a length to width aspect ratio of from about 1 to about 100 and wherein the length of the fibrous water insoluble material is less than about 0.2 mm. In certain embodiments, the amount of fines present in pulp prepared according to the present invention may be about 5.0% or less, such as about 2% or less, such as about 1% or less, such as from about 0.5 to about 2.0%. The fines content of pulp, on a length weighted basis, may be measured using an OpTest Fiber Quality Analyzer-360 (OpTest Equipment, Inc., Hawkesbury, ON) as described in the Test Methods section below. Generally, the percentage of fines on a length weighted basis is the sum of the fines length divided by the total length of fibers and fines in the sample.

[0033] As used herein, the term “brightness” generally refers to the optical brightness of a pulp sample measured in accordance with ISO 2470-1 :2016. Brightness is commonly expressed as a percentage (%).

[0034] As used herein, the term “debris” generally refers to the weight percentage of solids retained on a MasterScreen™ apparatus fitted with a screen having a slot size of 100 m (0.004 inches). The amount of debris in a given pulp sample is generally measured as set forth in the Test Methods section below.

[0035] As used herein, the term “caliper” is the representative thickness of a pulp sheet and is generally measured as described in the Test Methods section below. Caliper commonly has units of millimeters or microns.

[0036] As used herein, the term “Freeness” refers to the Canadian Standard Freeness (CSF) determined in accordance with TAPPI Standard T 227 OM-94. Freeness commonly has units of milliliters (mL).

[0037] As used herein, the term “fiber length” generally refers to the length weighted average fiber length (LWAFL) of fibers measured using an OpTest Fiber Quality Analyzer, model FQA-360 (OpTest Equipment, Inc., Hawkesbury, ON) as described in the Test Methods section below. Fiber length commonly has units of millimeters.

[0038] As used herein, the term “coarseness" generally refers to the weight per unit length of fiber measured using an OpTest Fiber Quality Analyzer-360 (OpTest Equipment, Inc., Hawkesbury, ON) as described in the Test Methods section below. Coarseness commonly has units of mass per unit length, such as milligrams per 100 meters (mg / 100 meters).

[0039] As used herein, the term “Hesperaloe fiber” refers to a fiber derived from a plant of the genus Hesperaloe of the family Asparagaceae including, for example, H. funifera, H. parviflora, H. nocturna, H. chiangii, H. tenuifolia, H. engelmannii, and H. malacophylla. The fibers are generally processed into a pulp for use in the manufacture of tissue products according to the present invention. Preferably the pulping process is a high yield pulping process, such as a pulping process having a yield greater than about 60 percent, such as from about 60 to about 90 percent and more preferably from about 65 to about 90 percent. The foregoing yields generally refer to the yield of unbleached hesperaloe fiber.

[0040] As used herein the term “synthetic thermoplastic fiber” means a non- cellulosic, thermoplastic fiber.

[0041] As used herein the term “thermoplastic” means a plastic or polymer which becomes pliable or moldable above a specific temperature and returns to a solid state upon cooling.

[0042] Exemplary thermoplastic fibers suitable for the present embodiments include polyesters (e.g., polyalkylene terephthalates such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and the like), polyalkylenes (e.g., polyethylenes, polypropylenes and the like), polyacrylonitriles (PAN), and polyamides (nylons, for example, nylon-6, nylon 6,6, nylon-6, 12, and the like). Preferred are PET fibers.

[0043] As used herein, the term “substantially free” means less than 3 wt%, alternatively less than 2 wt%, alternatively less than 1 wt%, alternatively less than 0.5 wt%, alternatively less than 0.25 wt%, alternatively less than 0.1 wt%, alternatively less than 0.05 wt%, alternatively less than 0.01 wt%, and / or alternatively free of. As used herein, “free of' means 0 wt%.

[0044] TEST METHODS

[0045] Fiber Properties

[0046] Fiber properties such as length, coarseness, percentage of fines, and fraction of very long fiber, are generally determined using an OpTest Fiber Quality Analyzer-360 (OpTest Equipment, Inc., Hawkesbury, ON) in accordance with the manufacturer's instructions. Samples are generally prepared by first accurately weighing a pulp sample. The sample mass may range from about 10 to about 50 mg (bone dry) and may be taken from a handsheet or pulp sheet. The weighed sample is diluted to a known consistency (between about 2 and about 10 mg / l). An aliquot of the diluted sample (usually 200 ml) is further diluted to a final volume of 600 ml and placed in the analyzer. The sample is then analyzed according to the manufacturer’s instructions and the output of the analyzer, such as the length weighted average fiber length, coarseness, length weighted fines, and a histogram illustrating the distribution of various fiber properties for a given sample are recorded. Generally, each reported fiber property is the average of three replicates. The output of the fiber quality analyzer is used to calculate the Very Long Fiber (VLF) fraction, which is the sum of fiber count from 6 to 14.95 mm divided by the total fiber count. Generally, the bin data output by the instrument, which provides the number of individual fibers counted within a given fiber length range, is used to determine VLF. The total number of individual fibers counted (N) and the total number of individual fibers counted having a length of 6 mm or greater (n) are determined from the bin data. The %VLF = n / N*100.

[0047] The output of the fiber quality analyzer is also used to calculate the ratio of the length weighted average fiber length (Lw) to the number average fiber length (Ln). Lw and Lnare calculated by the FQA software using the following equations:

[0048] Where n and L are determined by the instrument in the course of analyzing a sample. The ratio of the length weighted average fiber length (Lw) to the number average fiber length (Ln) indicates the fiber length distribution of the sample. A higher ratio is indicative of a broader fiber length distribution. A value of 1 indicates that all of the fibers in the sample have the same length.

[0049] Fiber coarseness is measured using the FQA instrument and is measured “as-is” without removal of fines. Consistency of the pulp sample is determined using TAPPI methods T-240 or the equivalent and the consistency (%) is recorded to the nearest 0.01 %. Based upon the measured consistency, the amount of undried sample required to yield approximately 0.015 grams of oven dried pulp is calculated and weighed out and the weight recorded to the nearest 0.0001 g. The weighed undried pulp is transferred to a British pulp disintegrator or equivalent pulp disintegrator and the total volume of the sample is diluted to 2 liters with deionized water and disintegrated 15,000 revolutions according to the manufacturer's instructions The disintegrated sample is further diluted with deionized water to a total volume of 5 liters ± 50 mL and the volume is recorded to the nearest 10 mL. The diluted sample is agitated by stirring and approximately 600 grams are weighted out into a clean beaker. The mass of the sample weighed out to the beaker is recorded to the nearest 0.1 g. The oven dried weight of the pulp sample to be analyzed is then calculated as shown in the equation below, and fiber analysis is carried out according to the manufacturer's instructions.

[0050] Caliper

[0051] Generally, sheets (e.g. webs) are dried and prepared for testing as set forth in TAPPI T 205 sp-02. Pulp sheets may be tested as is. Caliper is measured using an L & W Model code SE 050 Micrometer or equivalent. The micrometer has a circular pressure foot having an area of 2.0 cm2, a lowering speed of 1 .0 mm / second and a pressure of 50 kPa. Generally, caliper is reported as the average of five samples.

[0052] Basis Weight

[0053] Generally, sheets are dried and prepared for testing as set forth in TAPPI T 205 sp-02. Pulp sheets may be tested as is. The bone dry basis weight is generally measured by first cutting the samples to a specimen size of approximately 19.05 x 19.05 cm using an appropriate cutting tool. The cut sample is then placed on a balance in an oven preheated to 105 ± 2°C. Once the weight of the sample has stabilized, the weight is recorded to the nearest 0.01 gram. The bone dry basis weight equals the measured weight (W) multiplied by 27.56. Tensile Strength

[0054] Generally Tensile is measured by forming a sheet of a particular pulp, as described herein, and then testing the resulting sheet. Generally, sheets, such as nonwoven webs, are dried and prepared for testing as set forth in TAPPI T 205 sp-02. Samples are preconditioned and tested under TAPPI conditions (50 ± 2% relative humidity and 72 ± 1 ,8°F) as set forth in TAPPI T 402. Tensile testing is carried out substantially as described in TAPPI T 494 om-01 using an MTS Systems Sintech 11 S, Serial No. 6233 tensile testing instrument. The data acquisition software was an MTS TestWorks® for Windows Ver. 3.10 (MTS Systems Corp., Research Triangle Park, NC). During the test, stretch can also be measured, which is the stretch in percent prior to breaking. Generally, the tensile strengths of five samples are measured and averaged. Tensile strength generally has units of grams force (per unit sample width, such as g / 25.4 mm or g / 76.2mm (as used herein unless otherwise designated, the sample width is 76.2 mm)).

[0055] Wet Tensile Strength

[0056] Tensile testing of wet tissue samples, such as laminates of the present invention, is conducted on a tensile testing machine maintaining a constant rate of elongation and the width of each specimen tested is 1 inch or 3 inches. Generally products are tested in their product forms without separating into individual plies. For example, a 2-ply product is tested as two plies and recorded as such. The tensile tester, which is the same as described above, parameters are as follows: performed on dry base sheets. When testing dry base sheets, prior to testing, samples are soaked in tap water at room temperature. In such instances, 5 dry sheets of a sample are weighed and combined with 220% of water based on the weight of the sheets. The water is added to the sheets so that the sheets are saturated. The water can be applied to each side of the dry sheets using a syringe. The saturated sheets are then placed in a ZYPLOK bag and stored for a week. After a week, the samples are removed, cut into 1 inch or 3 inch strips, and tested immediately.

[0057] Five representative specimens are tested, and the arithmetic average of all individual specimen tests is recorded as the appropriate MD or CD tensile strength having units of grams force (per unit sample width, such as g / 25.4 mm or g / 76.2mm (as used herein unless otherwise designated, the sample width is 76.2 mm)). Stretch in percent can also be measured during the test. Debris

[0058] Debris is generally measured using a MasterScreen™ from Pulmac Systems International (Williston, VT). The MasterScreen™ is a low consistency screening device designed to mechanically separate fibers from contaminants. The MasterScreen™ is fitted with a screen (part no. 3390P) having a slot size of 100 m (0.004 inches). Screening of pulps using a MasterScreen type instrument is generally described in T-274.

[0059] Approximately 5 0 bone dry grams of fiber are used for the analysis. The sample may be taken from a handsheet, a pulpsheet or from wet lap pulp. The 5.0 g sample is mixed with 2 L of water and disintegrate using a benchtop disintegrator at 15,000 Revolution prior to testing. The sample is screened according to the manufacturer’s instructions and the rejects are collected in a collection cup fitted with a 150 mesh stainless steel screen. A wash cycle is run after the initial cycle to ensure that all of the debris retained by the screen is captured. Finally, the collection cup is rinsed with water and the rinse fluid is collected in a beaker. The rejects and wash fluid collected in the beaker is filtered under vacuum using a pre-weighed filter pad. Debris is collected on the filter pad, which is dried in an oven preheated to 105 °C overnight. The dried filter pad is weighed to the nearest 0.01 g and the weight percentage of debris is calculated. Generally, debris is reported as wt% and is the average of three samples.

[0060] DETAILED DESCRIPTION

[0061] It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only and is not intended as limiting the broader aspects of the present disclosure.

[0062] In general, the present disclosure is directed to hydroentangled nonwoven webs having excellent strength properties. In accordance with the present disclosure, the nonwoven webs contain non-wood fibers that can be used to displace synthetic thermoplastic fibers and / or synthetic cellulose fibers, such as regenerated cellulose fibers, and / or wood pulp fibers, such as softwood fibers. In one embodiment, the nonwoven web is substantially free or completely free of synthetic thermoplastic fibers. The hydroentangled nonwoven webs or sheet materials made according to the present disclosure have all different types of uses and applications and are particularly well suited for use as wipers. The product can be used as a dry product or can be premoistened and marketed as a moist wipe.

[0063] In one aspect, hydroentangled base sheets can be made in accordance with the present disclosure that contain non-wood pulp fibers such as Hesperaloe pulp fibers in combination with wood pulp fibers and regenerated cellulose fibers. The non-wood pulp fibers are more sustainable and less expensive than the other fibers. The non-wood pulp fibers can be used to replace a portion of the regenerated cellulose fibers and / or a portion of the wood pulp fibers while still producing a nonwoven web or base sheet having excellent physical properties. For example, hydroentangled base sheets made according to the present disclosure can display a wet tensile strength in the cross direction of greater than about 200 gf, such as greater than about 400 gf, such as greater than about 500 gf, such as greater than about 600 gf, such as greater than about 700 gf, such as greater than about 800 gf, and even greater than about 900 gf. The above results can be obtained at basis weights of less than about 70 gsm, such as less than about 65 gsm, such as from about 50 gsm to about 65 gsm.

[0064] The hydroentangled base sheets can also display an MD dry tensile strength of greater than about 800 gf, such as greater than about 1 ,000 gf, such as greater than about 1 ,500 gf, such as greater than about 2,000 gf, such as greater than about 2,500 gf, such as greater than about 3,000 gf, such as greater than about 3,500 gf, such as greater than about 4,000 gf, such as greater than about 4,500 gf, such as greater than about 5,000 gf. The above MD dry tensile strengths can be achieved on base sheets having a basis weight of less than about 70 gsm, such as less than about 65 gsm.

[0065] As described above, the hydroentangled base sheets of the present disclosure contain nonwood fibers in combination with regenerated cellulose fibers and wood pulp fibers.

[0066] It was discovered that base sheets made according to the present disclosure containing nonwood pulp fibers, such as Hesperaloe pulp fibers, can have a much higher tensile strength and wet tensile strength in relation to similar base sheets made with conventional wood pulp fibers, particularly Northern softwood kraft fibers or Southern softwood kraft fibers.

[0067] Although the base sheets can be formed using any suitable process, such as a conventional wetlaid process, in one embodiment, the hydroentangled base sheets of the present disclosure are produced according to a foam forming process. The foam forming process, for instance, in certain embodiments, is well suited to processing longer fibers.

[0068] The non-wood fibers can be derived from one or more plants of the genus Hesperaloe. The Hesperaloe fibers, for instance, can be obtained from Hesperaloe funifera, Hesperaloe parviflora, Hesperaloe noctuma, Hesperaloe chiangic, Hesperaloe tenuifolia, Hesperaloe engelmannii, Hesperaloe malacophylla, or mixtures thereof. In one particular aspect, the Hesperaloe fibers comprise Hesperaloe funifera fibers.

[0069] Of particular advantage, the non-wood fibers can be pulped without using the same pulping process for wood fibers. The pulping process for the non-wood fibers in comparison can be more environmentally friendly and requires less energy. The pulping process for the non-wood fibers, for instance, can comprise a mechanical pulping process alone or in combination with chemical treatments.

[0070] In one aspect, the pulping process for the non-wood fibers or Hesperaloe fibers can include harvesting biomass and cutting the biomass to an optimum size, such as having a nominal size of less than about 20 mm, such as less than about 10 mm. The cut biomass can then be passed through a press that compresses and mechanically treats the biomass in order to remove water-soluble components. The extracted and cut biomass can then be subjected to a second compression, optionally with maceration, using a screw press while impregnating the biomass with a first alkaline peroxide solution. The impregnated bagasse can then be fed to a refiner and combined with a second alkaline peroxide solution to form a primary pulp. During refining, the biomass can be fibrillated into pulp. After refining, the primary pulp can be diluted and subjected to cleaning and / or screening to further remove debris prior to an optional bleaching process. During cleaning, epidermal debris can be removed for producing a pulp having very low debris amount. For instance, the resulting pulp can contain debris in an amount less than about 5% by weight, such as in an amount less than about 2% by weight, such as in an amount less than about 1 .5% by weight, such as in an amount less than about 1% by weight. One embodiment of a process for pulping non-wood pulp is described in PCT Publication No. WO 2022 / 098963, which is incorporated herein by reference.

[0071] As described above, in producing the non-wood pulp fibers, the biomass is first cut to a desired size. The biomass may be cut to size at the time of harvesting using a forage harvester. The forage harvester, for instance, can use reciprocating knives, disc or rotary mowers, or large saw-like blades. The plant can be cut above the crown such as from about 10 to about 30 cm above the ground. The nominal chop length can be from about 5 to about 50 mm, such as from about 5 to about 30 mm, such as from about 5 to about 20 mm.

[0072] Cutting the biomass before the biomass is pulped or bleached can reduce the fraction of long fibers in the pulp. Further, the reduction in long fiber fraction may be achieved without a significant reduction in the fiber length. The resulting pulp, for instance, can have a length weighted average fiber length of greater than about 1 .5 mm, such as greater than about 1 .75 mm, such as greater than about 1 .8 mm, such as greater than about 2 mm, such as greater than about 2.2 mm, and less than about 3 mm.

[0073] After the biomass is harvested and cut, the biomass can be treated prior to pulping to remove at least a portion of the biomass epidermis and at least a portion of the water-soluble solids. Removal of the epidermis and water-soluble solids can be carried out simultaneously. The biomass epidermis originates from the cuticle of biomass leaves and is desirably removed for improving the efficiency of pulping and bleaching. In addition, removal of the epidermis reduces debris in the final product and may improve the physical properties of the resulting fibers. Removing the epidermis, for instance, can improve hand feel and softness and reduced lint in products made from the fibers.

[0074] Water-soluble solids and biomass epidermis can be removed, for instance, by subjecting the biomass to screw devices designed to compress and mechanically treat the biomass. The screw device can be a plug screw or other form of compression screw. In one aspect, the device is capable of a compression ratio of at least 2:1 , such as at least about 2.5:1 , such as at least about 3:1 , such as from about 2:1 to about 5:1.

[0075] During compression, the biomass can also be subjected to maceration for softening and separating the biomass into fibers and removing the epidermis and water-soluble solids. Compression can take place under a pressure of at least about 0.2 bars, such as at least about 0.5 bars, such as at least about 1 bar, such as from about 0.5 bars to about 1 .5 bars. The extracted and macerated bagasse is then converted to pulp by mechanical refining with, or without, the addition of chemicals, such as alkaline-based chemicals.

[0076] In certain preferred instances, non-wood pulps useful in preparing the products of the present invention are produced by a high yield pulping process. High yield pulping processes useful for the manufacture of high yield hesperaloe pulps include, for example, mechanical pulp (MP), refiner mechanical pulp (RMP), pressurized refiner mechanical pulp (PRMP), thermomechanical pulp (TMP), high temperature TMP (HT-TMP), RTS-TMP, thermopulp, groundwood pulp (GW), stone groundwood pulp (SGW), pressure groundwood pulp (PGW), super pressure groundwood pulp (PGW-S), thermo groundwood pulp (TGW), thermo stone groundwood pulp (TSGW) or any modifications and combinations thereof. Preferably the high yield pulping process has a yield greater than about 60 percent, such as from about 60 to about 90 percent and more preferably from about 65 to about 90 percent. The foregoing yields generally refer to the yield of unbleached hesperaloe pulp fiber. In certain instances, high yield hesperaloe pulps may be prepared as described in mechanical pulping process where the hesperaloe biomass or bagasse is treated with an alkaline phosphate prior to or during mechanical refining, such as described in PCT Application No. PCT / US2021 / 058196, the contents of which are incorporated herein in a manner consistent with the present invention.

[0077] In other instances, high yield hesperaloe pulps may be produced using a two-stage mechanical pulping process where fibrillation of the hesperaloe biomass or bagasse is carried out in first mechanical pulping stage without the addition of chemicals, such as alkaline peroxide chemicals, and / or other chemicals known in the art to bleach or otherwise process lignocellulosic material into pulp or precursors of pulp. Once the hesperaloe biomass or bagasse has been refined to a freeness of about 400 mL or greater, chemicals may be introduced, such as after a first mechanical pulping stage and prior to a second stage of mechanical refining. The foregoing process not only simplifies the pulping process and reduces costs, but it also improves pulp yields and the physical properties of the resulting pulp. For example, the foregoing process may be used to produce hesperaloe pulps at yields of about 80% or greater, such as about 85% or greater, such as about 90% or greater, such as yields from about 80% to about 95%.

[0078] In still other instances, high yield hesperaloe pulps may be produced without the addition of chemicals, such as alkaline peroxide chemicals, and / or other chemicals known in the art to bleach or otherwise process lignocellulosic material into pulp or precursors of pulp during mechanical refining of the pulp. The hesperaloe pulp may be produced using a process comprising the steps of: (a) providing a hesperaloe biomass; (b) cutting the biomass to a nominal length; (c) extracting water soluble solids from the cut biomass to produce a bagasse; (d) mechanically refining the bagasse at a first consistency and at a pH ranging from 6.5 to 7.5 without the addition of chemicals to yield a refined bagasse; (e) mechanically refining the refined bagasse at a pH ranging from 6.5 to 7.5 without the addition of chemicals at a second consistency, wherein the second consistency is less than the first consistency, to yield a high yield hesperaloe pulp useful in the manufacture of nonwoven products of the present invention.

[0079] While in certain instances caustic or an oxidizing agent may be introduced to the process to facilitate fiber separation by the mechanical forces, such addition may not be necessary and in certain instances may be undesirable. For example, in certain instances it may be desirable to produce hesperaloe pulp without the addition of caustic to improve yield and moderate the tensile strength of the resulting pulp. Without being bound by any particular theory, it is believed that omitting the addition of caustic during mechanic treatment, particularly mechanical treatment carried out a low consistency, such as consistencies of about 10% or less, particularly from about 3% to about 5%, improves pulp yield and reduces pulp tensile strength.

[0080] Although, in certain instances, a caustic or oxidizing agent may be added during processing, it is generally preferred that the hesperaloe pulp fiber is not pretreated with a sodium sulfite or the like prior to processing. For example, high yield hesperaloe pulps are generally prepared without pretreatment of the fiber with an aqueous solution of sodium sulfite, or the like, which is commonly employed in the manufacture of chemi-mechanical wood pulps.

[0081] The inventors have discovered that mechanical pulping of hesperaloe yields a pulp having a moderate fiber length, such as a fiber length of about 1 .50 mm or greater, such as from about 1 .50 mm to about 2.50 mm, yet a low degree of coarseness, such as less than about 10.0 mg / 100m, such as from about 3.5 to about 10.0 mg / 100 m. At the same time the pulp may have a moderate degree of tensile strength, such as a pulp Tensile Index of about 55 or less, such as from about 30 to about 55. Generally, the hesperaloe pulp fibers useful in the present invention have a relatively long fiber length, such as a fiber length of about 1 .50 mm or greater, such as about 1 .55 mm or greater, such as about 1 .60 mm or greater, such as about 1 .65 mm or greater, such as about 1 .70 mm or greater, such as about 1 .75 mm or greater, such as from about 1 .50 to about 2.50 mm, such as from about 1 .55 to about 2.00 mm. The hesperaloe pulp fibers may also have a fiber coarseness less than about 10.0 mg / 100m, such as less than about 8.0 mg / 100m, such as less than about 6.0 mg / 100m, such as from about 4.0 to about 10.0 mg / 100 m, such as from about 4.0 mg / 100 m to about 8.0 mg / 100m.

[0082] The hesperaloe pulps may also have a relatively modest degree of tensile strength, such as a Tensile Index of about 55 or less, such as about 50 or less, such as about 45 or less, such as about from about 30 to about 55, such as from about 35 to about 50, such as from about 35 to about 45. In other instances, the hesperaloe pulps may have a freeness, where a higher value is indicative of pulps that are more easily dewatered, of about 500 mL or greater, such as about 510 mL or greater, such as about 525 mL or greater, such as about 550 mL or greater, such as from about 500 mL to about 600 mL.

[0083] In other instances, the hesperaloe pulps may have a moderate degree of tensile strength and a low degree of fibers having a fiber length greater than 6.0 mm, which can inhibit dispersion of the pulp in water and cause stringing or clumping when the pulp is used to manufacture wet-laid fibrous products. For example, the inventive pulps may have a Tensile Index of about 55 or less, such as about 50 or less and a Very Long Fiber fraction (VLF) of about 1 .0% or less, such as about 0.75% or less, such as a about 0.50% or less, such as a VLF from about 0.05% to about 1 .0%.

[0084] In still other instances the hesperaloe pulps may have a high degree of brightness and / or low content of epidermis debris. Brightness and reduced debris are particularly important for pulps used in the manufacture of tissue products because of the need for a white, bright appearance and a low degree of linting. Accordingly, hesperaloe pulps useful in the present invention may have a Brightness of at least about 75%, more preferably at least about 78% and still more preferably at least about 80%. In other instances, the hesperaloe pulp may have a debris content of about 1 .0 wt% or less, such as about 0.90 wt% or less, such as about 0.80 wt% or less, such as about 0.60 wt% or less. In certain instances, it may be desirable to remove substantially all of the debris from the pulp such that the pulp is substantially free from, or free from, debris.

[0085] In general, base sheets or nonwoven webs made according to the present disclosure contain the non-wood pulp fibers or Hesperaloe pulp fibers in an amount greater than about 5% by weight. For instance, the base sheet can contain the non-wood pulp fibers or Hesperaloe pulp fibers in an amount greater than about 7% by weight, such as in an amount greater than about 10% by weight, such as in an amount greater than about 12% by weight, such as in an amount greater than about 15% by weight, such as in an amount greater than about 17% by weight, such as in an amount greater than about 20% by weight, such as in an amount greater than about 25% by weight. The non-wood pulp fibers or Hesperaloe fibers can be present in an amount less than about 55% by weight, such as in an amount less than about 50% by weight, such as in an amount less than about 45% by weight, such as in an amount less than about 40% by weight, such as in an amount less than about 35% by weight, such as in an amount less than about 30% by weight.

[0086] In addition to the non-wood fibers, base sheets made according to the present disclosure also contain staple fibers that may comprise regenerated cellulose fibers. The regenerated fibers are manmade filaments obtained by extruding or otherwise treating regenerated or modified cellulosic materials from woody or non-woody plants, as is known in the art. For example, but not by way of limitation, the regenerated fibers may include one or more of lyocell, viscose, or rayon, and the like. In some embodiments, the regenerated fibers have an average fiber length in the range of about 4 to about 20 millimeters, such as from about 5 to about 15 millimeters. Additionally, in some embodiments, the regenerated fibers may have a decitex in the range of about 0.7 g / 10,000 m to about 2 g / 10,000 m. Moreover, the decitex may be in the range of about 0.9 g / 10,000 m to about 1.1 g / 10,000 m. In one aspect, the regenerated cellulose fibers can also be crimped. In one suitable embodiment, the regenerated fibers are not mechanically treated to alter or otherwise affect the shape the fiber. More specifically, the regenerated fibers are not fibrillated.

[0087] The amount of staple fibers, such as regenerated cellulose fibers, contained in base sheets made according to the present disclosure is generally less than about 40% by weight. In one aspect, the amount of staple fibers, such as regenerated cellulose fibers, contained in base sheets made according to the present disclosure can be minimized due to the use of the non-wood pulp fibers. For instance, base sheets can be constructed in accordance with the present disclosure that contain staple fibers, such as regenerated cellulose staple fibers, in an amount no more than about 25% by weight. For instance, the base sheet can contain staple fibers, such as regenerated cellulose fibers, in an amount less than about 20% by weight, such as in an amount less than about 18% by weight, such as in an amount less than about 15% by weight, such as in an amount less than about 12% by weight, such as in an amount less than about 10% by weight, such as less than about 8% by weight, such as less than about 5% by weight, and in an amount greater than about 1 % by weight, such as in an amount greater than about 3% by weight, such as in an amount greater than about 5% by weight, such as in an amount greater than about 10% by weight.

[0088] Hydroentangled base sheets in accordance with the present disclosure can also contain wood pulp fibers. The wood pulp fibers can be obtained from deciduous and coniferous trees, including softwood fibers, such as Southern and Northern softwood kraft fibers, hardwood fibers, such as eucalyptus fibers, maple fibers, birch fibers, or aspen fibers, and mixtures thereof.

[0089] Pulp fibers can be prepared in high-yield or low-yield forms and can be pulped in any known method, including kraft, sulfite, high-yield pulping methods and other known pulping methods. Fibers prepared from organosolv pulping methods can also be used, including the fibers and methods disclosed in U.S. Pat. No. 4,793,898, U.S. Pat. No. 4,594,130, U.S. Pat. No. 3,585,104. Useful fibers can also be produced by anthraquinone pulping, exemplified by U.S. Pat. No. 5,595,628.

[0090] Chemically treated natural cellulosic fibers can be used such as mercerized pulps, chemically stiffened or crosslinked fibers, or sulfonated fibers. For good mechanical properties, it can be desirable that the fibers be relatively undamaged and largely unrefined or only lightly refined. Suitable cellulose pulp fibers can also include recycled fibers, virgin fibers, or mixes thereof. In certain embodiments capable of high bulk and good compressive properties, the fibers can have a Canadian Standard Freeness of at least 200, more specifically at least 300, more specifically still at least 400, and most specifically at least 500.

[0091] Other cellulose fibers that can be used in the present disclosure include high yield fibers. High yield pulp fibers are those papermaking fibers produced by pulping processes providing a yield of about 65% or greater, more specifically about 75% or greater, and still more specifically about 75% to about 95%. Yield is the resulting amount of processed fibers expressed as a percentage of the initial wood mass. Such pulping processes include bleached chemithermomechanical pulp (BCTMP), chemithermomechanical pulp (CTMP), pressure / pressure thermomechanical pulp (PTMP), thermomechanical pulp (TMP), thermomechanical chemical pulp (TMCP), high yield sulfite pulps, and high yield Kraft pulps, all of which leave the resulting fibers with high levels of lignin. High yield fibers are well known for their stiffness in both dry and wet states relative to typical chemically pulped fibers.

[0092] The cellulose pulp fibers can be present in the hydroentangled base sheet or nonwoven web generally in an amount greater than about 30% by weight, such as in an amount greater than about 40% by weight, such as in an amount greater than about 45% by weight, and in an amount less than about 90% by weight, such as in an amount less than about 85% by weight, such as in an amount less than about 80% by weight, such as in an amount less than about 75% by weight, such as in an amount less than about 70% by weight.

[0093] Optionally, the hydroentangled base sheet can contain relatively low amounts of synthetic thermoplastic fibers, such as polyester fibers, or polypropylene fibers. For instance, the base sheet can contain synthetic thermoplastic fibers in an amount less than about 5% by weight, such as in an amount less than about 4% by weight, such as in an amount less than about 3% by weight, such as in an amount less than about 2% by weight, such as in an amount less than about 1% by weight. In one aspect, the base sheet made according to the present disclosure is completely free of synthetic thermoplastic fibers. In fact, in one embodiment, the sheet product of the present disclosure can be completely free of fossil-based polymers. For example, the sheet products of the present disclosure can be free of polyolefin polymers (e.g. fibers) and / or free of polyester polymers (e.g. fibers).

[0094] As described above, base sheets or nonwoven webs made according to the present disclosure can use any suitable process. The process, for instance, can be a wetlaid process incorporating hydroentangling jets or can be a foam forming process incorporating hydroentangling jets. In one aspect, for instance, a foam forming process is used that is particularly well suited to accommodating longer fibers. FIGS. 1 and 2, for instance, represent one embodiment of a foam forming process that may be used to produce base sheets in accordance with the present disclosure. It should be understood, however, that the embodiment illustrated in FIGS. 1 and 2 is merely for exemplary purposes.

[0095] In one aspect, the process includes first selecting a fiber furnish containing non-wood pulp fibers, particularly Hesperaloe pulp fibers, regenerated cellulose fibers, and wood pulp fibers. The fiber furnish is then fed to a web forming process which can be a foam forming process in which the newly formed web is also subjected to a hydroentangling step. After hydroentangling the fibers, the nonwoven web can then be fed to a drying process. The drying process can include through-air dryers, heated drums, or combinations thereof.

[0096] When the base sheet is foam formed, the fiber furnish can be combined with a foam to create a foamed suspension. The fibers, for instance, can be blended with water and a foaming agent.

[0097] The foaming agent, for instance, may comprise any suitable surfactant. In one embodiment, for instance, the foaming agent may comprise sodium lauryl sulfate, which is also known as sodium laureth sulfate or sodium lauryl ether sulfate. In one embodiment, the foaming agent is a nonionic surfactant which may comprise an alkyl polyglycoside. The foaming agent, for instance, can be a C8 alkyl polyglycoside, a C10 alkyl polyglycoside, or a mixture of C8 and C10 alkyl polyglycosides.

[0098] Other foaming agents include sodium dodecyl sulfate or ammonium lauryl sulfate. In other embodiments, the foaming agent may comprise any suitable cationic and / or amphoteric surfactant. For instance, other foaming agents include fatty acid amines, amides, amine oxides, fatty acid quaternary compounds, and the like.

[0099] The foaming agent is combined with water generally in an amount greater than about 0.05% by weight, such as in an amount greater than about 0.07% by weight, such as in an amount greater than about 0.1% by weight. One or more foaming agents are generally present in an amount less than about 50% by weight, such as in an amount less than about 10% by weight, such as in an amount less than about 2% by weight, such as in an amount less than about 0.5% by weight.

[0100] Once the foaming agent and water are combined, the mixture is blended or otherwise subjected to forces capable of forming a foam. A foam generally refers to a porous matrix, which is an aggregate of hollow cells or bubbles which may be interconnected to form channels or capillaries.

[0101] The foam density can vary depending upon the particular application and various factors including the fiber furnish used. In one embodiment, for instance, the foam density of the foam can be greater than about 200 g / L, such as greater than about 250 g / L, such as greater than about 300 g / L. The foam density is generally less than about 600 g / L, such as less than about 500 g / L, such as less than about 400 g / L, such as less than about 350 g / L. In one embodiment, for instance, a lower density foam is used having a foam density of generally less than about 350 g / L, such as less than about 340 g / L, such as less than about 330 g / L. The foam will generally have an air content of greater than about 30%, such as greater than about 40%, such as greater than about 50%, such as greater than about 60%. The air content is generally less than about 80% by volume, such as less than about 70% by volume, such as less than about 65% by volume.

[0102] In order to form the nonwoven web, the foam is combined with a selected fiber furnish in conjunction with any auxiliary agents. The foamed suspension of fibers is then pumped to a tank and from the tank is fed to a headbox. FIGS. 1 and 2, for instance, show one embodiment of a process in accordance with the present disclosure for forming the web. As shown particularly in FIG. 2, the foamed fiber suspension can be fed to a tank 12 and then fed to the headbox 110. From the headbox 110, the foamed fiber suspension is issued onto an endless traveling forming fabric 26 supported and driven by rolls 28 in order to form a web 10. As shown in FIG. 2, a forming board 14 may be positioned below the web 10 adjacent to the headbox 110. Once formed on the forming fabric 26, the foam formed web can have a consistency of less than about 50%, such as less than about 20%, such as less than about 10%, such as less than about 5%. In fact, the forming consistency can be less than about 4, such as less than about 3.5, such as less than about 3. The forming consistency is generally greater than about 0.5, such as greater than about 0 8. The forming consistency indicates the ability to produce webs according to the present disclosure while minimizing the amount of water needed during formation.

[0103] Once the wet web is formed on the forming fabric 26, the web is conveyed downstream and dewatered. For instance, the process can optionally include a plurality of vacuum devices 16, such as vacuum boxes and vacuum rolls. The vacuum boxes assist in removing moisture from the newly formed web 10.

[0104] As shown in FIG. 2, the forming fabric 26 may also be placed in communication with a steambox 18 positioned above a pair of vacuum rolls 20. The steambox 18, for instance, can increase dryness and reduce cross-directional moisture variance. The applied steam from the steambox 18 heats the moisture in the wet web 10 causing the water in the web to drain more readily, especially in conjunction with the vacuum rolls 20. From the forming fabric 26, the newly formed web 10, in the embodiment shown in FIG. 1 , is conveyed downstream, subjected to hydroentangling, and dried on a through-air dryer.

[0105] After the foam formed web has been produced, the web is subjected to one or more hydroentangling steps. In the embodiment illustrated in FIG. 2, for instance, the web 10 is subjected to two different hydroentangling steps. In particular, in FIG. 2, the web 10 is hydroentangled on a first surface during a first hydroentangling step and then hydroentangled on a second and opposite surface during a second hydroentangling step. As shown in FIG. 2, for example, the process can include a first hydroentangling device 30 and a second hydroentangling device 32. In one aspect, the first hydroentangling device 30 and the second hydroentangling device 32 can include drums on which the nonwoven web is conveyed. Alternatively, the hydroentangling devices can comprise horizontal tables.

[0106] The hydroentangling that occurs at each hydroentangling station may be accomplished utilizing conventional hydroentangling equipment. The hydroentangling of the foam formed web may be carried out with any appropriate working fluid such as, for example, water. The working fluid flows through a manifold which evenly distributes the fluid through a series of individual holes or orifices. Exemplary holes or orifices, for example, can have a diameter of from about 10 microns to about 200 microns. For example, the manifold may include a strip of orifices having a diameter of about 20 microns to about 50 microns. The manifold may contain about 20 to about 40 holes per inch and can include 1 to 3 rows of holes. Many other manifold configurations and combinations may be used. In the embodiment illustrated in FIG. 2, for instance, the hydroentangling device 30 includes a plurality of injectors 34, while the hydroentangling device 32 includes a plurality of injectors 36. The injectors 34 and 36 can be part of the manifold and can be in communication with a working fluid supply. In the embodiment illustrated in FIGS. 1 and 2, the first hydroentangling device 30 includes four banks of waterjets or injectors 34 and the second hydroentangling device 32 also includes four banks of water jets or injectors 36. It should be understood, however, that each hydroentangling device can include a single bank, two banks, three banks, four banks, five banks, six banks, or more of water jets.

[0107] During the hydroentangling process, the working fluid can pass through the orifices at pressures ranging from about 10 bar to about 300 bar, such as from about 20 bar to about 250 bar. Bonds between the fibers of the nonwoven web are created through hydroentangling. Thus, hydroentangling can increase the strength, such as the dray and wet strength of the nonwoven web or base sheet. Increasing the pressure during hydroentangling can increase the strength of the web that is formed.

[0108] The fluid impacts the material or web which can be supported on a foraminous surface or wire or may be supported on a porous drum surface. In the embodiment illustrated in FIG. 2, for instance, hydroentangling occurs on a first drum 38 and a second drum 40.

[0109] When supported on a foraminous surface or wire during hydroentangling, the wire can have a mesh size of from about 40x40 to about 100x100. The wire or surface may also be a multi-ply mesh having a mesh size of from about 50x50 to about 200x200. In one aspect, only one side of the web 10 is hydroentangled.

[0110] As described above, alternatively, the web 10 can be placed directly onto the surface of the drum 38 and on the surface of the drum 40 during hydroentangling. Each drum can include a plurality of openings or vacuum passages for withdrawing excess water. These openings or vacuum passages can also create a pattern into the web 10 during the hydroentangling process. For example, a pattern can be formed into one surface of the web at the first hydroentangling station and a pattern can be formed into the second and opposite surface of the web at the second hydroentangling station. The pattern formed into each surface of the web 10 can be highly distinctive and can increase the aesthetic appeal of nonwoven materials made from the web. In addition, the pattern formed into the web can be three-dimensional including hills and valleys. This three-dimensional topography can further improve various properties of the material.

[0111] Once the foam formed web 10 is hydroentangled one or more times, the web can be dried using a non-compressive drying operation. For example, as shown in FIG. 1, the foam formed web can be dried using a through-air dryer.

[0112] Referring to FIG. 1, the foam formed and hydraulically entangled web 10 is transferred from the drum 40 to a throughdrying fabric 44 with the aid of a vacuum transfer roll 46 or a vacuum transfer shoe. If desired, the throughdrying fabric can be run at a slower speed than the web 10 to further enhance stretch. Transfer can be carried out with vacuum assistance to ensure deformation of the sheet to conform to the throughdrying fabric, thus yielding desired bulk and appearance if desired.

[0113] In the embodiment illustrated in FIG. 1 , the foam formed web 10 is transferred to a throughdrying fabric 44. Alternatively, the foam formed web can be transferred to a metal, porous sleeve that forms the circumference of the throughdryer 48.

[0114] Alternatively, the foam formed web 10 can be conveyed on the throughdrying fabric 44 over the circumference of the throughdryer 48. The throughdrying fabric can contain high and long impression knuckles. For example, the throughdrying fabric can have about from about 5 to about 300 impression knuckles per square inch which are raised at least about 0.005 inches above the plane of the fabric. During drying, the web can be further macroscopically arranged to conform to the surface of the throughdrying fabric. Flat surfaces, however, can also be used in the present disclosure.

[0115] The side of the web contacting the throughdrying fabric is typically referred to as the "fabric side" of the nonwoven web. The fabric side of the nonwoven web, as described above, may have a shape that conforms to the surface of the throughdrying fabric after the fabric is dried in the throughdryer. The opposite side of the nonwoven web, on the other hand, is typically referred to as the "air side". The air side of the web is typically smoother than the fabric side during normal throughdrying processes.

[0116] The level of vacuum used for the web transfers can be from about 3 to about 15 inches of mercury (75 to about 380 millimeters of mercury), preferably about 5 inches (125 millimeters) of mercury. The vacuum shoe or roll (negative pressure) can be supplemented or replaced by the use of positive pressure from the opposite side of the web to blow the web onto the next fabric in addition to or as a replacement for sucking it onto the next fabric with vacuum.

[0117] The web is finally dried to a consistency of about 94 percent or greater by the throughdryer 48 and thereafter transferred to a carrier fabric 50. The dried basesheet 52 is transported to the reel 54 using carrier fabric 50 and an optional carrier fabric 56. An optional pressurized turning roll 58 can be used to facilitate transfer of the web from carrier fabric 50 to fabric 56. Suitable carrier fabrics for this purpose are Albany International 84M or 94M and Asten 959 or 937, all of which are relatively smooth fabrics having a fine pattern. Although not shown, reel calendering or subsequent off-line calendering can be used to improve the smoothness and softness of the basesheet.

[0118] In one embodiment, the resulting foam formed web 52 is a textured web, which has been dried in a three-dimensional state. The texture in the web can be created due to the hydroentangling stations, due to the manner in which the web is dried using the through-dryer 48 or can be a result of both processes. For example, the web 52 can be dried while still including a pattern formed into the web.

[0119] The basis weight of webs made in accordance with the present disclosure can vary depending upon the final product. In general, the basis weight of the products may vary from about 30 gsm to about 100 gsm. The basis weight, for instance, can be greater than about 45 gsm, such as greater than about 50 gsm, such as greater than about 55 gsm, and generally less than about 80 gsm, such as less than about 75 gsm, such as less than about 70 gsm, such as less than about 65 gsm.

[0120] The process of the present disclosure can also produce webs with good bulk characteristics. The dry bulk, for instance, can generally be greater than about 3 cc / g, such as greater than about 5 cc / g, such as greater than about 8 cc / g, and generally less than about 20 cc / g, such as less than about 15 cc / g.

[0121] As described above, nonwoven webs or base sheets made according to the present disclosure also have excellent strength properties especially when tested for dry tensile strength in the machine direction or wet tensile strength in the cross direction. In addition, the base sheet can display a cross direction dry tensile strength of greater than about 1 ,000 gf, such as greater than about 1 ,500 gf, such as greater than about 2,000 gf, such as greater than about 2,300 gf, such as greater than about 2,500 gf. The base sheet can display a machine direction wet tensile strength of greater than about 500 gf, such as greater than about 700 gf, such as greater than about 1 ,000 gf.

[0122] In one embodiment, the nonwoven material can be cut into individual sheets. The wipers may have any suitable size and shape. In one embodiment, the wiper can have a width of from about 8 cm to about 100 cm, such as from about 10 cm to about 50 cm, such as from about 20 cm to about 25 cm. The length of the wiper can be from about 10 cm to about 200 cm, such as from about 20 cm to about 100 cm, such as from about 35 cm to about 45 cm.

[0123] Wipers made according to the present disclosure can be distributed as dry wipers or as moist wipes. In one aspect, the wiper can be pre-moistened with a wetting solution, such as water, a solvent, a waterless hand cleanser, or any other suitable liquid. The liquid may contain antiseptics, surfactants, emollients, humectants, and so forth. Generally, each wiper contains greater than about 100 wt. %, in some embodiments from about 150 to about 1500 wt. %, and in some embodiments, from about 300 to about 1200 wt. % of the liquid based on the dry weight of the wiper.

[0124] The wipers may be packaged in a variety of forms, materials and / or containers, including, but not limited to, rolls, boxes, tubs, flexible packaging materials, and so forth. Some examples of suitable containers include rigid tubs, film pouches, etc.

[0125] The present disclosure may be better understood with reference to the following example.

[0126] Example

[0127] Various foam formed base sheets were produced according to the present disclosure containing Hesperaloe pulp fibers. The Hesperaloe pulp fibers were combined with Southern softwood kraft pulp fibers and regenerated cellulose fibers, namely lyocell fibers. For purposes of comparison, two base sheets were formed that did not contain any Hesperaloe pulp fibers.

[0128] The Hesperaloe pulp fibers used had a length weight average fiber length of from about 1.9 mm to about 2.4 mm. The regenerated cellulose fibers used were TENCEL lyocell fibers commercially available from Lenzing. The lyocell fibers had a size of about 1 .7 dtex, had an average fiber length of 12 mm, and were crimped.

[0129] The base sheets were made using a foam forming process including a hydroentangling step similar to the process illustrated in FIGS. 1 and 2.

[0130] The following base sheets were produced:

[0131] As shown, Sample No. 9 contained Southern softwood kraft fibers in combination with bleached chemi-thermomechanical pulp (BCTMP).

[0132] The base sheets were tested for various mechanical properties when dry and when wet and the following results were obtained:

[0133] As shown above, adding greater amounts of Hesperaloe fibers dramatically and unexpectedly increased the physical properties of the base webs when dry or wet. The above results demonstrate that base sheets can be formed containing a reduced amount of regenerated cellulose fibers and / or a reduced amount of Southern softwood kraft fibers and replaced with non-wood fibers for producing base webs with comparable or actually better properties.

[0134] These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only and is not intended to limit the invention so further described in such appended claims.

Claims

What Is Claimed:1 . A sheet product comprising a base sheet having a machine direction and cross direction, the base sheet comprising: non-wood pulp fibers in an amount of greater than about 5% by weight, the non-wood pulp fibers having a coarseness of less than about 10 mg / 100 m and having an average fiber length of from about 1.5 mm to about 2.5 mm; wood pulp fibers; regenerated cellulose fibers in an amount greater than 0% by weight and in an amount up to about 40% by weight; and wherein the base sheet has been hydroentangled and wherein the base sheet displays a wet tensile strength in the cross direction of greater than about from about 200 gf.

2. A sheet product as defined in claim 1 , wherein the base sheet contains the non-wood fibers in an amount of from about 5% by weight to about 55% by weight, such as from about 5% by weight to about 30% by weight.

3. A sheet product as defined in claim 1 or 2, wherein the base sheet contains the regenerated cellulose fibers in an amount of from about 5% by weight to about 28% by weight, such as from about 10% by weight to about 20% by weight.4 A sheet product as defined in any of the preceding claims, wherein the non-wood fibers are derived from one or more plants of the genus Hesperaloe.

5. A sheet product as defined in claim 5, wherein the non-wood fibers are obtained from Hesperaloe funifera, Hesperaloe parvlflora, Hesperaloe noctuma, Hesperaloe chiangic, Hesperaloe tenuifolia, Hesperaloe engelmannii, Hesperaloe malacophylla, or mixtures thereof.

6. A sheet product as defined in any of the preceding claims, wherein the non-wood fibers comprise Hesperaloe funifera fibers.

7. A sheet product as defined in any of the preceding claims, wherein the base sheet displays a wet tensile strength in the cross direction of greater than about 300 gf, such as greater than about 400 gf, such as greater than about 500 gf, such as greater than about 600 gf.

8. A sheet product as defined in any of the preceding claims, wherein the base sheet displays a tensile strength in the machine direction of greater than about 800 gf, such as greater than about 1000 gf, such as greater than about 1500 gf, such as greater than about 2000 gf.

9. A sheet product as defined in any of the preceding claims, wherein the product further comprises a wetting solution incorporated into the base sheet.

10. A sheet product as defined in any of the preceding claims, wherein the regenerated cellulose fibers have an average fiber length of from about 4 mm to about 20 mm, such as from about 5 mm to about 15 mm, and have a decitex of from about 0.7 g / 10,000 m to about 2 g / 10,000 m.

11. A sheet product as defined in any of the preceding claims, wherein the regenerated cellulose fibers comprise lyocell fibers.

12. A sheet product as defined in any of the preceding claims, wherein the wood pulp fibers comprise softwood pulp fibers, the softwood pulp fibers being present in the base sheet in an amount of at least about 40% by weight.

13. A sheet product as defined in any of the preceding claims, wherein the base sheet comprises a foam formed base sheet.

14. A sheet product as defined in any of the preceding claims, wherein the base sheet comprises a single ply web that is non-layered.

15. A sheet product as defined in any of the preceding claims, wherein the base sheet has a basis weight of from about 30 gsm to about 100 gsm, such as from about 55 gsm to about 70 gsm.

16. A sheet product as defined in any of the preceding claims, comprising a plurality of individual sheets comprising the base sheet, the individual sheets being in a stacked arrangement.

17. A sheet product as defined in any of the preceding claims, wherein the base sheet does not contain any synthetic thermoplastic fibers.

18. A sheet product as defined in any of the preceding claims, wherein the base sheet has a basis weight of from about 55 gsm to about 70 gsm and displays a wet tensile strength in the cross direction of greater than about 500 gf, such as greater than about 600 gf, such as greater than about 700 gf, such as greater than about 800 gf.

19. A sheet product as defined in claim 18, wherein the base sheet displays a tensile strength in the machine direction of greater than about 2000 gf, such as greater than about 2500 gf, such as greater than about 3000 gf, such as greater than about 3500 gf.

20. A wet wipe product comprising: a base sheet comprising non-wood pulp fibers in an amount of greater than about 5% by weight, the non-wood pulp fibers having a coarseness of less than about 10 mg / 100 m and having an average fiber length of from about 1 .5 mm to about 3 mm, the base sheet further comprising wood pulp fibers and regenerated cellulose fibers, the regenerated cellulose fibers being present in the base sheet in an amount greater than 0% by weight and in an amount up to about 30% by weight; a wetting solution incorporated into the base sheet; andwherein the base sheet has been hydroentangled and wherein the base sheet displays a wet tensile strength in the cross direction of greater than about from about 200 gf.

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