Foam-forming fiber web constructed from microfibers

Abstract

Nonwoven materials containing cellulose pulp fibers combined with microfibers are disclosed. The microfibers also have a relatively long length. By utilizing a foam forming process, the fibers can be uniformly mixed together to produce a fiber web with significantly high strength properties. By using microfibers, the fiber number / area can be greatly increased, thereby creating a fiber network within the nonwoven structure.

Description

[0001] Cross-references to related applications

[0002] This application relates to and has priority with U.S. Provisional Patent Application No. 63 / 594,090, filed October 30, 2023, which is incorporated herein by reference in its entirety for all purposes. Background Technology

[0003] Household and industrial wipes are typically used to pick up and absorb both polar and non-polar liquids. Wipes should be constructed with sufficient absorbency to retain the liquid within the wipe's structure. Furthermore, wipes should possess good physical strength and abrasion resistance to withstand the tearing, tensile, and abrasive forces frequently applied during use.

[0004] Conventional wiping products are made of woven and knitted fabrics. These wiping materials have been used in all different types of industries, such as industrial applications, food service applications, health and medical applications, and for general consumer use.

[0005] In the past, nonwoven wipes were also constructed from sizing fibers alone or in combination with synthetic fibers. For example, spunbond webs made of continuous filaments were historically hydroentangled with sizing fibers to produce resilient wipes. In many cases, these webs were used for single-use applications and then discarded. Although these wipes had good levels of strength and absorbency, they generally did not possess the same cleaning properties as woven and knitted fabrics, especially when wiping away oils and greases.

[0006] In view of the above, there is a need for a disposable nonwoven wiping material that possesses increased strength properties while having a much lower basis weight than conventional textile wipes. In one aspect, there is a need for a disposable wiping product with a very high fiber-to-basis-weight ratio, not only to increase strength but also to improve many other properties and characteristics of the product. Summary of the Invention

[0007] Generally speaking, this disclosure relates to nonwoven fiber webs containing microfibers. In one aspect, the nonwoven fiber web is formed by a foam forming process that not only processes microfibers but also combines microfibers with other fibers, such as pulp fibers, to produce nonwoven fiber webs with a surprisingly better balance of properties at a lower basis weight. Previously, such nonwoven fiber webs could not be formed using conventional wet-laid papermaking processes.

[0008] In one aspect, for example, this disclosure relates to a nonwoven product comprising a nonwoven fiber web containing microfibers blended with cellulose pulp fibers. The microfibers may have an average length greater than about 8 mm, such as greater than about 10 mm, such as greater than about 11 mm and less than about 50 mm, such as less than about 20 mm. The microfibers may have fiber sizes less than about 1.8 denier, such as less than about 1.4 denier, such as less than about 1.2 denier, such as less than about 1 denier, such as less than about 0.8 denier, such as less than about 0.7 denier, such as less than about 0.6 denier and greater than about 0.25 denier, such as greater than about 0.3 denier. The microfibers may comprise synthetic polymer fibers or regenerated cellulose fibers. The fiber web may have a basis weight less than about 100 gsm, such as less than about 80 gsm, such as less than about 70 gsm and greater than about 25 gsm, such as greater than about 40 gsm, such as greater than about 50 gsm. In one respect, nonwoven fiber webs can have a basis weight of about 52 gsm to about 68 gsm.

[0009] According to this disclosure, a nonwoven fiber web may contain more than about 2,800,000 fibers / m. 2 Such as greater than approximately 5,000,000 fibers / m 2 Such as greater than approximately 10,000,000 fibers / m 2 Such as greater than approximately 20,000,000 fibers / m 2 Such as greater than approximately 30,000,000 fibers / m 2 Such as greater than approximately 40,000,000 fibers / m 2 Such as greater than approximately 50,000,000 fibers / m 2、 Such as greater than approximately 60,000,000 fibers / m 2 The amount of microfibers. The amount of microfibers contained in nonwoven fiber webs can also be greater than about 50,000 linear meters / m. 2 Such as greater than approximately 100,000 linear meters / m 2 Such as greater than approximately 150,000 linear meters / m 2 Such as greater than approximately 200,000 linear meters / m 2 Such as greater than approximately 300,000 linear meters / m 2 Such as greater than approximately 400,000 linear meters / m 2 Such as greater than approximately 500,000 linear meters / m 2 And typically less than about 1,500,000 linear meters / m 2 .

[0010] Nonwoven fiber webs can exhibit a value greater than approximately 0.07 g / cm³. 3Such as greater than approximately 0.09 g / cm³ 3 Such as greater than about 0.1 g / cm 3 Such as greater than approximately 0.11 g / cm³ 3 And less than approximately 0.2 g / cm³ 3 The density.

[0011] As described above, in one aspect, the nonwoven fiber web may include a foam-formed fiber web. The nonwoven fiber web may also undergo at least one hydroentangling step. For example, in one aspect, the foam-formed fiber web may include a first surface and an opposing second surface, wherein the first surface has been hydroentangled, and the second surface has been hydroentangled. The foam-formed fiber web may include a non-layered, single-layer sheet fiber web. The resulting fiber web may contain a residual amount of foaming agent. Foaming agents may include, for example, lauryl sulfate, glycosides, sodium lauryl sulfate, ammonium lauryl sulfate, fatty acid amines, amides, amine oxides, or fatty acid quaternary compounds.

[0012] Depending on the fiber size, microfibers can be present in the nonwoven fiber web in an amount typically from about 10% to about 50% by weight. In one embodiment, the microfibers may comprise polymeric synthetic fibers, such as polyester or polyolefin fibers. Alternatively, the microfibers may comprise regenerated cellulose fibers, such as viscose, lyocell, etc. In one aspect, the microfibers may comprise crimped fibers. For example, the fiber may contain more than about 2 crimps / cm.

[0013] The nonwoven fiber web manufactured according to the present invention exhibits an excellent balance of physical properties. For example, the nonwoven fiber web can exhibit longitudinal tensile strength greater than about 5,000 gf, such as greater than about 6,000 gf, such as greater than about 7,000 gf, such as greater than about 8,000 gf, such as greater than about 9,000 gf and less than about 20,000 gf. The nonwoven fiber web can exhibit transverse tensile strength 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 and less than about 10,000 gf. Nonwoven fiber webs can exhibit longitudinal tensile strengths greater than about 2,500 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, such as greater than about 5,500 gf and less than about 12,000 gf. Nonwoven fiber webs can exhibit transverse tensile strengths 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 3,200 gf and less than about 10,000 gf.

[0014] Nonwoven fiber webs may also exhibit longitudinal trapezoidal tear strength 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 2,200 gf and less than about 6,000 gf. Nonwoven fiber webs may exhibit transverse trapezoidal tear strength greater than about 500 gf, such as greater than about 1,000 gf, such as greater than about 1,500 gf and less than about 5,000 gf.

[0015] The nonwoven fiber web manufactured according to the present invention has numerous and different applications and uses. In one specific embodiment, the nonwoven fiber web can be an industrial wiping material. The wiping material may comprise multiple individual sheets stacked together, or it may comprise a spirally wound product. In one aspect, the nonwoven product may be pre-saturated with a cleaning solvent.

[0016] This disclosure also relates to a nonwoven fiber web comprising ultrafine synthetic polymer fibers blended with cellulose pulp fibers. The ultrafine synthetic fibers may have an average length greater than about 8 mm and a fiber size less than about 0.8 denier. The ultrafine synthetic polymer fibers may be present in the nonwoven fiber web in an amount from about 10% to about 50% by weight. In one aspect, the ultrafine synthetic polymer fibers may include crimped fibers.

[0017] This disclosure also relates to a nonwoven product comprising a nonwoven fiber web containing ultrafine synthetic fibers blended with cellulose pulp fibers. The ultrafine synthetic fibers may have an average length greater than about 8 mm and a fiber size less than about 0.8 denier. The nonwoven fiber web may exhibit a longitudinal tensile strength greater than about 7000 gf, a transverse tensile strength greater than about 3500 gf, a longitudinal wet tensile strength greater than about 4000 gf, a transverse wet tensile strength greater than about 2500 gf, a longitudinal trapezoidal tear strength greater than about 2000 gf, a transverse trapezoidal tear strength greater than about 1500 gf, and a basis weight of about 45 gsm to about 70 gsm.

[0018] Other features and aspects of this disclosure are discussed in more detail below. Attached Figure Description

[0019] The full and practical disclosure of this invention is set forth in more detail in the remainder of the specification, including with reference to the accompanying drawings, in which:

[0020] Figure 1 This is a diagram of one embodiment of the process for producing a substrate according to this disclosure;

[0021] Figure 2 yes Figure 1A diagram of a magnified portion of the illustrated process;

[0022] Figure 3 This is a perspective view of a wiping product manufactured according to this disclosure;

[0023] Figure 4 This is a perspective view of another embodiment of the wiping product manufactured according to this disclosure; and

[0024] Figure 5 This is a diagram used to explain the bonded and unbonded fibers for the purpose of manufacturing nonwoven materials according to this disclosure.

[0025] The repeated use of reference numerals in this specification and drawings is intended to indicate the same or similar features or elements of the invention.

[0026] definition

[0027] As used herein, the term "longitudinal" refers to the direction of travel of the shaped surface on which the fibers are deposited during the formation of the nonwoven fiber web.

[0028] As used in this article, the term "lateral" refers to a direction perpendicular to the longitudinal direction as defined above.

[0029] As used herein, the term "cellulose pulp fiber" refers to fibers derived from natural sources such as woody and non-woody plants. Woody plants include, for example, deciduous and coniferous trees. Non-woody plants include, for example, cotton, flax, fine-stemmed needlegrass, milkweed, rice straw, jute, hemp, and bagasse. "Pulp fiber" refers to delignified cellulose fibers and may include hardwood fibers, softwood fibers, and mixtures thereof.

[0030] As used herein, the term "average fiber length" refers to the average length of fibers, fiber bundles, and / or fibrous materials determined by measurement using microscopic techniques. A sample of at least 20 randomly selected fibers was isolated from a fiber liquid suspension. The fibers were placed on a microscope slide prepared to suspend the fibers in water. A staining dye was added to the suspended fibers to color the cellulose-containing fibers, thereby distinguishing or separating them from synthetic fibers. The slide was placed under a Fisher Stereomaster II microscope—S 19642 / S 19643 series. Measurements were taken of the 20 fibers in the sample using a 0–20 mil scale at 20X linear magnification, and the average length, minimum and maximum length, and deviation or coefficient of variation were calculated. In some cases, the average fiber length is calculated as a weighted average length of the fibers (e.g., fibers, fiber bundles, fibrous materials), determined by a device such as the Kajaani Oy Electronics FS-200 Kajaani Fiber Analyzer, available for purchase from Kajaani, Finland. According to standard testing procedures, the sample is treated with an impregnation solution to ensure the absence of fiber bundles or debris. Each sample is decomposed in hot water and diluted to a suspension of approximately 0.001%. When testing using the standard Kajaani fiber analysis test procedure, each test sample is drawn from the diluted suspension in portions of approximately 50 ml to 100 ml. The weighted average fiber length can be an arithmetic mean, a length-weighted mean, or a weight-weighted mean, and can be expressed by the following equation:

[0031]

[0032] in

[0033] k = maximum fiber length

[0034] x i =Fiber length

[0035] n i = The number of fibers with length xi

[0036] n = the total number of fibers measured.

[0037] One characteristic of the average fiber length data measured by the Cajani fiber analyzer is that it does not distinguish between different types of fibers. Therefore, the average length represents the average length of all different types (if any) of fibers in the sample.

[0038] As used herein, the term "short fiber" refers to a discontinuous fiber made from synthetic polymers (such as polypropylene, polyester, post-consumer recycled (PCR) fibers, polyester, nylon, etc.) or cellulosic fibers (such as cotton fibers, bast fibers, regenerated cellulose fibers (e.g., viscose, rayon, etc.)). Short fibers can be diced fibers, etc. Short fibers can have cross-sections that are round, bicomponent, multicomponent, molded, hollow, etc.

[0039] As used herein, the term "nonwoven fiber web or material" refers to a fiber web having a single-fiber structure in which the fibers are interwoven, but not in a identifiable manner as in knitted or woven fabrics. Nonwoven materials include, for example, carded fiber webs, wet-laid fiber webs, air-laid fiber webs, foam-molded fiber webs, etc.

[0040] As used herein, the term "thickness" refers to the representative thickness of a single sheet measured using an EMVECO 200-A Microgage automated micrometer (EMVECO, Inc., Newberg, Oreg.) according to TAPPI test method T402. (The thickness of a sheet product comprising two or more layers is the thickness of a single sheet product comprising all layers.) The micrometer has an anvil diameter of 2.22 inches (56.4 mm) and an anvil pressure of 132 g / cm² (2.0 kPa) per 6.45 cm².

[0041] As used in this article, the term "sheet volume" refers to the quotient of thickness (usually in μm) divided by oven-dry basis weight (usually in gsm).

[0042] As used herein, the “tensile test” is performed according to TAPPI test method T-576 “Tensive properties of towel and tissue products (with constant elongation)”, wherein the test is performed on a tensile testing machine that maintains constant elongation, and each test specimen is 3 inches wide. More specifically, specimens for dry tensile strength testing are prepared by cutting strips 3 inches ± 0.05 inches (76.2 mm ± 1.3 mm) wide in the longitudinal (MD) or transverse (CD) orientation using a JDC precision sample cutter (Thwing-Albert Instrument Company, Philadelphia, PA, model JDC 3-10, serial number 37333) or equivalent. The instrument used to measure tensile strength is an MTS Systems Sintech 11S, serial number 6233. The data acquisition software is MTS TestWorks for Windows Ver. 3.10. ®(MTS Systems Corp., Research Triangle Park, NC). A force sensor was selected from a maximum value of 50 N or 100 N, depending on the strength of the sample being tested, such that most of the peak load values ​​fell between 10% and 90% of the force sensor's full-scale value. For cosmetic paper and towels, the gauge length between the jaws was 4 inches ± 0.04 inches (101.6 mm ± 1 mm), and for toilet paper, the gauge length between the jaws was 2 inches ± 0.02 inches (50.8 mm ± 0.5 mm). The jaw speed was 10 inches / min ± 0.4 inches / min (254 mm / min ± 1 mm / min), and the breaking sensitivity was set to 65%. The sample was placed in the instrument's jaws, vertically and horizontally centered. The test was then started and ended when the sample broke. Depending on the orientation of the sample being tested, the peak load was recorded as the sample's "MD tensile strength" or "CD tensile strength". For each product or sheet, ten representative specimens are tested, and the arithmetic mean of all individual specimen tests is recorded as the appropriate MD or CD tensile strength of the product or sheet, in grams of force per 3-inch sample. The geometric mean tensile (GMT) strength is calculated and expressed in grams of force per 3-inch sample width. Tensile energy absorption (TEA) and slope are also calculated using a tensile testing machine. TEA is expressed in gm·cm / cm. 2 Reported in units. Slope is recorded in kg. Both TEA and slope are direction-dependent, and therefore MD and CD directions are measured independently. The geometric mean TEA and geometric mean slope are defined as the square root of the product of the representative MD and CD values ​​for a given property.

[0043] As used herein, “wet tensile strength” measurements are performed on a tensile testing machine that maintains a constant elongation, and each test specimen is one (1) inch wide. Typically, the product is tested in its product form. The tensile testing machine is the same as described above, with the following parameters:

[0044] Chuck speed 304.8±10 mm / min (12±0.4 inches / minute) Spacing 76±1mm (3±0.04 inches) Load unit K-Force Full scale load Use an appropriate load cell for the material being tested, so that the value falls between 5% and 95% of the full-scale load. fracture sensitivity 70% Slope preset point 70 grams and 157 grams

[0045] Wet tensile strength measurements can be performed on a pre-wetted swab or on a dry substrate. When testing a dry substrate, the sample is soaked in tap water at room temperature before testing. In this case, five dry samples are weighed and mixed with water at 220% of the sheet weight. Water is added to the sheet until it is saturated. Water can be applied to each side of the dry sheet using a syringe. The saturated sheet is then placed in a ZYPLOK bag and stored for one week. After one week, the samples are removed, cut into 1-inch strips, and tested immediately.

[0046] The trapezoidal, or "loop-tear," test is a tension test applicable to nonwoven fiber webs. The entire width of the specimen is clamped between fixtures, so the test primarily measures the bond or interlocking strength of individual fibers directly under tensile load, rather than the overall strength of the composite structure of the fabric. The test measures the fabric's resistance to tear propagation at a constant elongation rate. A piece of fabric cut at one edge is clamped and pulled along the non-parallel side of the trapezoidal specimen, thus inducing tear propagation perpendicular to the load within the specimen. The test can be performed along the MD or CD direction. For the loop-tear test, a trapezoidal outline is drawn on a 3-inch × 6-inch (75 mm × 152 mm) specimen, with the longer dimension in the test direction, and the specimen is cut into a trapezoidal shape. The trapezoid has a 4-inch (102 mm) side and a 1-inch (25 mm) side, which are parallel and 3 inches (76 mm) apart. A small initial cut of ⅝ inches (15 mm) is made in the middle of the shorter parallel side. Clamp the sample in, for example, an Instron Model available from Instron Corporation, 2500 Washington St., Canton, Mass. ™ (Constant elongation rate tester) or the Thwing-Albert Model INTELLECT II, ​​available from Thwing-Albert Instrument Co., 10960 Dutton Rd., Phila., Pa. 19154, features 3-inch (76 mm) long parallel clamps. The specimen is clamped along the non-parallel sides of the trapezoid, such that the fabric is loose along the longer side and taut along the shorter side, with a cut made in the middle between the clamps. A continuous load is applied to the specimen, causing the tear to propagate across the specimen width. Note that the longer direction is the direction of the test, even if the tear is perpendicular to the length of the specimen. The force required to completely tear the specimen is recorded in pounds, with higher values ​​indicating greater tear resistance. The test method used conforms to ASTM standard test D1117-14, except that the tear load is calculated as the average of the first and highest recorded peaks, rather than the average of the lowest and highest recorded peaks. Typically, five specimens are tested for each sample. The data presented includes the first peak and the highest peak.

[0047] As used herein, “bubbling resistance” or “Gelbo bubbling value” is determined using counting method C according to INDA standard procedure 160.1.RO (12). This test determines the relative number of particles released from the nonwoven material when the nonwoven material is subjected to flexural and torsional movements.

[0048] As used herein, the Martindale Wear test measures the relative resistance of a sample to wear according to World Strategic Partners (“WSP”) standard test number 20.5 (08). A circular specimen with a diameter of 165 mm ± 6.4 mm and an area of ​​18,258 sq mm is subjected to the required number of cycles (10 or 60) in the presence of an abrasive at a pressure of 9 kPa. The abrasive is a 36-inch × 4-inch × 0.05-thickness silicone rubber wheel reinforced with glass fiber, with a surface hardness of 81A (Shore A 81 ± 9). The specimen is examined for surface fuzzing (fiber porosity), pilling (small accumulations of fibers), streaks, delamination, or porosity, and a numerical rating of 1, 2, 3, 4, or 5 is assigned based on comparison with a set of similarly numbered standard photographs, where “1” indicates maximum wear and “5” indicates minimum wear. The tests were conducted using a Martindale abrasion and wear tester, such as the model 103 or 403 from James H. Heal & Company, Ltd., West Yorkshire, England.

[0049] As used herein, the term "hot spot bonding" generally refers to a process, for example, by passing material between patterned rollers (e.g., burnishing rollers) and another roller (e.g., support rollers), which may or may not be patterned. Typically, one or both of these rollers are heated.

[0050] As used herein, the term "ultrasonic welding" generally refers to a process, for example, by passing material between an ultrasonic welding head and a patterning roller (e.g., a support roller). For example, ultrasonic welding using a fixed welding head and a rotating patterned support roller is described in U.S. Patent No. 3,939,033 to Grgach et al., U.S. Patent No. 3,844,869 to Rust Jr., and U.S. Patent No. 4,259,399 to Hill, all of which are incorporated herein by reference in their entirety for all purposes. Furthermore, ultrasonic welding using a rotating welding head and a rotating patterned support roller is described in U.S. Patent No. 5,096,532 to Neuwirth et al., U.S. Patent No. 5,110,403 to Ehlert, and U.S. Patent No. 5,817,199 to Brennecke et al., all of which are incorporated herein by reference in their entirety for all purposes. Of course, the invention may also employ any other ultrasonic welding technique.

[0051] As used herein, “vertical absorbance” is a measure of the amount of water absorbed by a nonwoven product (single or multiple layers) or sheet, expressed as water or oil per gram of fiber (dry weight). Specifically, vertical absorbance is determined by cutting a sheet of the product to be tested (which may contain one or more layers) into a square measuring 100 mm × 100 mm (±1 mm). The resulting test specimen is weighed to an accuracy of 0.01 g and recorded as “dry weight.” The sample is attached to a 3-point clamping device and suspended from one corner of the device, with the opposite corner lower than the rest of the sample. The sample and clamp are then immersed in a dish of water or oil for 3 minutes (±5 seconds). The water should be distilled or deionized water at 23 ± 3 °C. At the end of the immersion, the sample and clamp are removed from the water or oil. The clamping device should minimize the influence of clamping area and pressure on the test results. Specifically, the clamping area should be only large enough to hold the sample, and the pressure should be only sufficient to hold the sample while minimizing the amount of water removed from the sample during clamping. Allow the sample to drain for 3 minutes (±5 seconds). At the end of the draining, remove the sample by holding the weighing pan below it and releasing it from the clamping device. Then weigh the wet sample to two decimal places in grams (0.01 g) and record this value as “wet weight”. Vertical absorption capacity in grams / gram = [(wet weight - dry weight) / dry weight]. Perform at least five (5) repeated measurements on representative samples from the same roll or box of products to obtain the average value of the vertical absorption capacity. The same test can also be performed horizontally.

[0052] As used herein, the "vertical wicking" test is used to measure the height of water that can be vertically wicked by a sample over a given time period. A reservoir containing purified distilled / deionized water is provided. One end of a 25 mm × 203 mm (1 inch × 8 inch) sample is clamped, and the other end is placed in the fluid such that it extends 2.5 cm therein. The apparatus shown in Figure 7 of U.S. Patent Publication No. 2007 / 0010153 is used. Paper clips or other weights can be used to weigh the lower end of the sample to prevent curling and to ensure easy immersion of the lower end in water. A support block holds the sample at a fixed height. The degree of liquid migration, measured in centimeters, is measured at intervals of 15, 30, 45, and 60 seconds. A ruler or other device can be used to determine the degree of liquid migration of the sample. The test is performed in a laboratory atmosphere at 23 ± ℃ and 50 ± 5% RH. The vertical wicking value of the sample is given as the average of at least three samples. The vertical wicking test can be performed on a sample taken longitudinally or laterally.

[0053] As used herein, the "static and dynamic coefficients of friction" test can be performed according to ASTM D 1894-08 using a high-gloss smooth vinyl tile sliding surface. A slide with the test specimen attached is pulled across the high-gloss smooth vinyl tile surface. The test specimen and the vinyl tile surface are in face-to-face contact. The coefficient of friction value is defined as a measure of the relative difficulty of sliding the test specimen surface across the fixed vinyl tile surface. The "static" coefficient of friction is the highest instantaneous value obtained at the start of movement between the surfaces, and the "dynamic" coefficient of friction is the average of the values ​​obtained during a 60-second test (6-inch travel distance). The testing equipment can be a LAB MASTER sliding and friction model 32-90 and a test slide of model 32.90-06; both are available from Testing Machines, Inc., Islanda, NY, 11722, USA.

[0054] The test board may weigh 200 grams. Testing is conducted in a room with a temperature between approximately 22°C and 24°C and a relative humidity of approximately 50%. The test material is mounted onto a platform (table) approximately 305 mm long and 102 mm to 127 mm wide using double-sided tape. The test specimen has a length of approximately 100 mm and a width of approximately 63 mm. The test board is lowered by the testing equipment before testing, and when the test begins, the board is gently positioned onto the test material to prevent any unnatural adhesion formation. The length of the board is parallel to the length of the mounting surface. The moving platform is then moved at a speed of 6 inches per minute. The instrument acquires readings and continues to do so for approximately 60 seconds (6 inches traveled). The instrument measures and stores the "static" value of the highest instantaneous coefficient of friction obtained during the initial movement between the surfaces within the first inch of the pull. The "dynamic" value is obtained and stored as the average of the values ​​obtained during the 60-second test (6-inch travel distance).

[0055] As used herein, the fiber quantity in linear meters per square meter (m²) and the number of fibers per m² are calculated from the measured basis weight of the nonwoven fiber web and the known weight percentage of the microfibers in the web. The number of fibers per square meter is calculated based on the above and on the average weight of the specific fiber (microfiber). Once the number of fibers per square meter is calculated, the fiber quantity in linear meters per square meter can be calculated (by multiplication) based on the average fiber length. Detailed Implementation

[0056] Those skilled in the art will understand that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of this disclosure.

[0057] In the past, attempts have been made to combine pulp fibers, such as cellulose fibers, with longer short fibers. However, such fiber mixtures are very difficult to handle in conventional wet web forming processes because only relatively short straight fibers can be transported in the aqueous medium during the formation of the fiber web. Longer fibers tend to clump and aggregate when combined with sufficient water to produce a fiber web. However, this disclosure uses a foam forming process to combine cellulose fibers with ultrafine and relatively long synthetic fibers. The foam forming process produces an integrated and entangled fiber matrix, resulting in a nonwoven material with an excellent balance of properties at a relatively low basis weight.

[0058] More specifically, relatively long microfibers have been found to offer numerous benefits and advantages in the production of nonwoven materials when combined with cellulose fibers. Microfibers, such as microfibers, have historically been used to produce yarns for manufacturing woven fabrics, which can then be used to produce garments. However, their use in nonwoven materials has been limited by difficulties encountered in handling and processing the fibers. However, when used in foam-forming processes, microfibers can be combined with cellulose fibers to produce nonwoven materials with uniform and homogeneous properties.

[0059] It has been found that incorporating microfibers into nonwoven materials can produce nonwoven fiber webs containing a greater amount of fiber at the same basis weight.

[0060] When producing nonwoven fiber webs containing synthetic short fibers combined with cellulose pulp fibers, increasing the ratio of short fibers to basis weight can be controlled in three different ways: 1) adding a larger proportion of short fibers to the nonwoven material relative to cellulose pulp fibers; 2) cutting the short fibers to shorter lengths; or 3) reducing the fiber size while maintaining the same ratio of short fibers to cellulose pulp fibers.

[0061] Incorporating a combination of synthetic staple fibers and cellulose fibers into nonwoven materials can improve product properties. However, staple fibers are relatively more expensive, and therefore it is preferable to minimize the total proportion of staple fibers in the fiber web. Thus, adding a larger proportion of staple fibers under (1) above would not only unnecessarily increase costs but also result in a less sustainable nonwoven material that may require a longer time to biodegrade. Cutting staple fibers into shorter lengths to increase fiber weight / basis weight ((2) above) is also not preferred. However, shorter fibers result in fewer bonding points and lower strength and integrity of the fiber web.

[0062] Therefore, this disclosure relates to the use of finer or lower denier fibers, which, according to this disclosure, can produce a uniform fiber web that reaches a critical fiber mass at a lower weight. Although unknown, it is believed that the ultrafine fibers of this disclosure create a permeable fiber network within a nonwoven material. A fiber permeable network refers to the behavior of randomly distributed fibers within a matrix or medium. In a fiber permeable network, there is a random distribution of fibers within a given space, and the concept of permeation refers to the formation of continuous paths or interconnected clusters of fibers. Although unknown, it is believed that nonwoven materials containing ultrafine fibers manufactured according to this disclosure produce a permeable fiber network that results in extremely high strength and other physical property values ​​due to the fiber density reaching which fibers begin to form a connecting network spanning the entire system. By using ultrafine fibers, a permeable network can be formed without increasing the basis weight of the material by conventional amounts. For example, Figure 5 This shows the differences in fiber critical quality required to generate a fiber-permeable network. For example... Figure 5 As shown, for example, a fiber permeation network 500 is illustrated, in which all fibers are interconnected at multiple bonding points. However, the bottom figure 600 shows a threshold of critical quality or density of the fibers not being reached, resulting in unconnected fiber clusters.

[0063] Because the longer, ultrafine fibers of this disclosure can exist in a large number and / or density of fibers at a lower basis weight in a nonwoven fiber web, it is believed that a permeable fiber network is produced, which produces a material with extremely high strength values. For example, a nonwoven fiber web having a basis weight of less than 100 gsm, such as even less than about 70 gsm, can exhibit longitudinal tensile strengths greater than about 5,000 gf, such as greater than about 6,000 gf, such as greater than about 7,000 gf, such as greater than about 8,000 gf, such as even greater than about 9,000 gf, and can exhibit transverse tensile strengths 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.

[0064] The nonwoven fiber webs described above can exhibit longitudinal wet tensile strengths greater than about 2,500 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, such as even greater than about 5,500 gf. The nonwoven fiber webs can exhibit transverse tensile strengths 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 3,200 gf.

[0065] In one respect, the strength along the longitudinal direction and the strength along the transverse direction can be relatively uniform. For example, the ratio of longitudinal to transverse tensile strength can be about 2.5 or less, such as less than about 2.3, such as less than about 2, and can be about 1 or greater.

[0066] Nonwoven fiber webs also exhibit excellent tear properties. For example, nonwoven fiber webs can exhibit longitudinal trapezoidal tear strength 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 2,200 gf. Nonwoven fiber webs can exhibit transverse trapezoidal tear strength greater than about 500 gf, such as greater than about 1,000 gf, such as greater than about 1,500 gf.

[0067] As described above, the aforementioned properties can be obtained at relatively low basis weights. For example, the basis weight of nonwoven fiber webs can be less than about 100 gsm, such as less than about 90 gsm, such as less than about 80 gsm, such as less than about 70 gsm and greater than about 30 gsm, such as greater than about 40 gsm, such as greater than about 45 gsm. In one aspect, the basis weight of nonwoven materials can be from about 40 gsm to about 70 gsm, such as from about 52 gsm to about 68 gsm.

[0068] Furthermore, by using ultrafine long fibers, the amount of synthetic fibers incorporated into nonwoven materials can be relatively low, while still obtaining an interconnected fiber network that produces significantly enhanced strength properties. For example, the amount of ultrafine fibers contained in the nonwoven material can be less than about 50% by weight, such as less than about 45% by weight, such as less than about 40% by weight, such as less than about 35% by weight, such as less than about 30% by weight, such as less than about 25% by weight, and typically greater than about 10% by weight, such as greater than about 15% by weight. In one aspect, the nonwoven fiber web can contain ultrafine fibers in a content of only about 15% by weight to about 25% by weight.

[0069] The weight percentage or proportion of microfibers contained in a nonwoven fiber web can be kept relatively low because a greater number of fibers or a higher fiber density is achieved by using microfibers. More specifically, the inventors have found that, contrary to examining the weight percentage of fibers present in the fiber web, the number / area of ​​fibers contained in the nonwoven fiber web and the linear length / area of ​​the fibers result in improved properties. For example, a nonwoven fiber web manufactured according to this disclosure may contain more than about 2,800,000 fibers / m. 2 The amount of ultrafine fibers. For example, a nonwoven fiber web can contain more than about 5,000,000 fibers / m. 2 Such as greater than approximately 8,000,000 fibers / m 2 Such as greater than approximately 10,000,000 fibers / m 2Such as greater than approximately 12,000,000 fibers / m 2 Such as greater than approximately 15,000,000 fibers / m 2 Such as greater than approximately 17,000,000 fibers / m 2 Such as greater than approximately 20,000,000 fibers / m 2 Such as greater than approximately 25,000,000 fibers / m 2 Such as greater than approximately 30,000,000 fibers / m 2 Such as greater than approximately 35,000,000 fibers / m 2 Such as greater than approximately 40,000,000 fibers / m 2 Such as greater than approximately 45,000,000 fibers / m 2 Such as greater than approximately 50,000,000 fibers / m 2 Such as greater than approximately 55,000,000 fibers / m 2 Such as greater than approximately 60,000,000 fibers / m 2 And typically less than approximately 3,000,000,000 fibers / m 2 The actual number / area of ​​fibers can depend on the size of the fibers, the length of the fibers, and the product being constructed.

[0070] As described above, microfibers can be combined with shorter cellulose pulp fibers. Suitable cellulose pulp fibers include, but are not limited to, non-wood fibers such as cotton, abaca, kenaf, sabaigrass, flax, esparto grass, straw, jute, bagasse, milkweed fiber, and pineapple leaf fiber; and woody or pulp fibers, such as those obtained from deciduous and coniferous trees, including softwood fibers such as northern and southern softwood kraft paper fibers; and hardwood fibers such as eucalyptus, maple, birch, and aspen. Pulp fibers can be prepared in high-yield or low-yield forms and can be pulped by any known method, including kraft paper pulping, sulfite pulping, high-yield pulping methods, and other known pulping methods. Fibers prepared by organic solvent pulping methods can also be used, including the fibers and methods disclosed in U.S. Patent Nos. 4,793,898, 4,594,130, and 3,585,104. Useful fibers can also be produced by anthraquinone pulping, as illustrated in U.S. Patent No. 5,595,628.

[0071] Chemically treated natural cellulose fibers, such as mercerized sizing, chemically hardened or cross-linked fibers, or sulfonated fibers, can be used. For good mechanical properties, it may be desirable for the fibers to be relatively undamaged and substantially unrefined or only lightly refined. Suitable cellulose sizing fibers may also include regenerated fibers, virgin fibers, or mixtures thereof. In some embodiments that enable high volumetric properties and good compressibility, the fibers may have a Canadian standard freeness of at least 200, more specifically at least 300, even more specifically at least 400, and most specifically at least 500.

[0072] Other cellulosic fibers that can be used in this disclosure include high-yield fibers. High-yield pulp fibers are those papermaking fibers produced by pulping processes that provide a yield of about 65% or higher, more specifically about 75% or higher, and even more specifically about 75% to about 95%. Yield is the amount of processed fiber obtained 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 pulp, and high-yield kraft pulp, all of which result in fibers with a high lignin content. High-yield fibers are well known for their stiffness in both dry and wet conditions relative to typical chemically pulped fibers.

[0073] Cellulose pulp fibers can be present in the nonwoven fiber web in an amount typically from about 50% to about 95% by weight, including all increments of 1% by weight therein. For example, cellulose pulp fibers can be present in the nonwoven fiber web in an amount greater than about 70% by weight, such as in an amount greater than about 75% by weight, such as in an amount greater than about 77% 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 83% by weight.

[0074] According to this disclosure, cellulose pulp fibers are combined with microfibers. In one aspect, the microfibers include synthetic polymer fibers. Alternatively, the microfibers include synthetic cellulose fibers, such as regenerated cellulose fibers. The microfibers can be straight or crimped short fibers.

[0075] The size of microfibers can vary depending on the specific application. Microfibers are typically about 1.8 denier or smaller. For example, microfibers can have sizes such as less than about 1.6 denier, less than about 1.4 denier, less than about 1.2 denier, less than about 1 denier, less than about 0.9 denier, less than about 0.8 denier, less than about 0.7 denier, or less than about 0.6 denier. Microfibers can also have sizes greater than about 0.09 denier, such as greater than about 0.2 denier, or greater than about 0.3 denier. It has been found that reducing fiber size also allows for a reduction in the weight percentage of fibers incorporated into the nonwoven fiber web while still maintaining the desired level of fiber count / area or fiber linear length / area.

[0076] Microfibers can have an average fiber length greater than about 6 mm, such as greater than about 8 mm, such as greater than about 10 mm. The average fiber length can be less than about 100 mm, such as less than about 80 mm, such as less than about 60 mm, such as less than about 40 mm, such as less than about 25 mm, such as less than about 20 mm, such as less than about 15 mm.

[0077] As described above, microfibers can be polymer synthetic fibers, regenerated cellulose fibers, or mixtures thereof. Synthetic polymer fibers include, for example, polyester fibers, such as fibers containing polyethylene terephthalate. Other synthetic polymer fibers include polyolefin fibers, such as polypropylene fibers, polyethylene fibers, and copolymers thereof. Synthetic polymer fibers can comprise monofilament fibers or bicomponent fibers.

[0078] Regenerated cellulose fibers can include rayon filaments obtained by extrusion or other processing of regenerated or modified cellulose materials from woody or non-woody plants. For example, regenerated cellulose fibers can include lyocell fibers, viscose fibers, rayon fibers, etc. Regenerated cellulose fibers can be produced by dissolving cellulose in a suitable solvent and then extruding the solution through a suitable fiber preparation device (such as a spinneret) to produce filaments, which can then be cut to the desired length.

[0079] As described above, in one aspect, microfibers can include crimped fibers. Creped fibers exhibit a degree of waviness in which the fiber axis deviates from a straight line and follows a simple, complex, or irregular wavy path. In its simplest form, crimp is uniplanar and regular, resembling a sine wave, but is typically much more complex and irregular. An example of three-dimensional crimp is helical crimp. Crepiness can be expressed numerically as the number of crimps per unit length, or as the difference in distance between two points on the fiber when it is relaxed and when it is straightened under appropriate tension.

[0080] Synthetic fibers can be wound or crimped using a variety of different techniques. In one embodiment, for example, the fiber can be a single-component fiber formed from a polymer or mixture of polymers that causes the fiber to be wound or crimped when heat-treated. However, in other embodiments, synthetic fibers can be wound or crimped using chemical or mechanical means. Three-dimensional synthetic fibers may include fibers wound in two dimensions and / or spiral fibers.

[0081] In one embodiment, the crimped fiber may comprise a multicomponent fiber, such as a bicomponent fiber. Bicomponent fibers may contain different polymers in a side-by-side configuration or an island configuration. The presence of two different polymers can cause the fiber to crimp or coil when heat-treated or subjected to mechanical means. For example, the fiber can be heat-treated by passing it under a hot air knife or hot air diffuser. The crimping may be due to differential cooling of the polymer components of the fiber. After the fiber crimps or coils, it may optionally undergo further heat treatment steps to lock it into a three-dimensional conformation. Synthetic fibers can be made from all different types of polymers, including polyolefin polymers such as polyethylene and / or polypropylene, polyester polymers, polyamide polymers, etc. In one embodiment, the synthetic fiber is a bicomponent fiber made of polyethylene and polypropylene. In one embodiment, the polyethylene may have greater crystallinity, which causes the polyethylene chains to recrystallize upon cooling, resulting in shrinkage of the polyethylene polymer and inducing crimping or coiling into fibers.

[0082] Other multicomponent fibers that can be used according to this disclosure include bicomponent fibers having a skin-core configuration, wherein a polyethylene polymer is used to form the skin, and the core is made of a polyester polymer (such as polyethylene terephthalate polymer). Alternatively, a bicomponent fiber may include a first polyester polymer to form the skin, and the core is made of a second polyester polymer. Both polyester polymers may include polyethylene terephthalate polymers. If desired, many of the bicomponent fibers described above can also be used as bonding fibers. For example, when subjected to a certain amount of heat, the skin polymer on one fiber can bond to the skin polymer on an adjacent fiber.

[0083] In another embodiment, the crimped fiber may comprise a bicomponent fiber containing a first polymer composition separate from the second polymer composition. The first polymer composition may contain a crimping-reinforcing additive that causes the fiber to crimp. For example, the crimping-reinforcing additive may comprise a polymer having a rapid crystallization rate. For example, in one embodiment, the crimping-reinforcing additive may comprise a polypropylene homopolymer.

[0084] Synthetic cellulose fibers, such as regenerated cellulose fibers, can be crimped using any suitable mechanical or chemical method. In one respect, for example, regenerated cellulose fibers can be crimped by means of dry steam.

[0085] The crimped fibers according to this disclosure typically contain more than 1.5 crimps / cm, such as about 2 crimps / cm to about 15 crimps / cm. For example, the fibers may contain more than about 2 crimps / cm, such as more than about 2.2 crimps / cm, such as more than about 2.7 crimps / cm, such as more than about 3 crimps / cm, such as more than about 3.2 crimps / cm, such as more than about 3.5 crimps / cm, such as more than about 3.8 crimps / cm, such as more than about 4 crimps / cm, such as more than about 4.2 crimps / cm, such as more than about 4.5 crimps / cm, such as more than about 4.8 crimps / cm, such as more than about 5 crimps / cm, such as more than about 5.2 crimps / cm, such as more than about 5.5 crimps / cm, such as more than about 5.7 crimps / cm, such as more than about 6 crimps / cm. In other embodiments, the crimped fibers may contain greater than about 6.5 crimps / cm, such as greater than about 7 crimps / cm, such as greater than about 7.5 crimps / cm, such as greater than about 8 crimps / cm, such as greater than about 10 crimps / cm, such as greater than about 12 crimps / cm, and typically less than about 20 crimps / cm, such as less than about 15 crimps / cm.

[0086] As described above, the nonwoven fiber web of this disclosure can be manufactured by a foam forming process. It has been found that, for example, foam forming processes can successfully process microfibers, even if the fibers are relatively long and crimped. Optionally, the nonwoven fiber web may also undergo one or more bonding steps during formation, such as one or more hydroentangling steps and / or thermal bonding steps.

[0087] Foam forming processes offer numerous advantages and benefits. During foam forming, water is replaced by foam, which acts as a carrier for the fibers forming the fibrous web. The foam, representing a large amount of air, is blended with cellulose and / or microfibers. Because less water is used to form the fibrous web, less energy is required to dry it. Furthermore, foam forming processes are better suited for producing nonwoven materials containing different types of fibers, especially longer and / or crimped fibers. Additionally, surface morphologies can be incorporated into the nonwoven material, where raised elements have a larger basis weight than the surrounding area of ​​the fibrous web. Moreover, foam forming processes can produce unique fiber orientations. For example, when producing nonwoven materials from a combination of shorter fibers (such as pulp fibers) and longer fibers (such as synthetic microfibers), the shorter fibers tend to accumulate in the raised elements, while the longer fibers can have a greater density along the substrate surface. This structure produces nonwoven materials with greater fiber density and absorbency in the raised elements while exhibiting significant strength between the raised elements.

[0088] In a particular implementation scheme, such as Figure 1 and Figure 2As shown, for illustrative purposes only, the nonwoven materials of this disclosure can be produced using foam forming processes and optionally in combination with a hydroentangling step. For example, the hydroentangling step can occur on a patterned surface that creates a morphology on the nonwoven material. Not shown, in addition to or instead of hydroentangling the material, the nonwoven material can also undergo thermal bonding processes, such as hot spot bonding processes.

[0089] Initially, fiber formulations were selected for the production of nonwoven materials. As described above, fiber formulations may contain cellulose pulp fibers bonded with microfibers. During foam formation, the fiber formulations are combined with foam produced by mixing water with a foaming agent.

[0090] The blowing agent may, for example, contain any suitable surfactant. In one embodiment, the blowing agent may, for example, comprise sodium lauryl sulfate, also known as sodium lauryl polyoxyethylene ether sulfate or sodium lauryl ether sulfate. In one embodiment, the blowing agent is a nonionic surfactant, which may comprise an alkyl polyglycoside. For example, the blowing agent may be a C8 alkyl polyglycoside, a C10 alkyl polyglycoside, or a mixture of C8 and C10 alkyl polyglycosides.

[0091] Other blowing agents include sodium dodecyl sulfate or ammonium lauryl sulfate. In other embodiments, the blowing agent may contain any suitable cationic and / or amphoteric surfactants. For example, other blowing agents include fatty acid amines, amides, amine oxides, fatty acid quaternary compounds, etc.

[0092] The foaming agent is typically mixed with water in an amount greater than about 0.1% by weight, such as greater than about 1% by weight, such as greater than about 2% by weight, such as greater than about 3% by weight. One or more foaming agents are typically present in an amount less than about 50% by weight, such as less than about 10% by weight, such as less than about 8% by weight, such as less than about 4% by weight.

[0093] Once the foaming agent and water are mixed, the mixture is either blended or otherwise subjected to forces capable of forming foam. Foam generally refers to a porous matrix, which is an aggregate of hollow units or bubbles that can interconnect to form channels or capillaries.

[0094] Foam density can vary depending on the specific application and various factors, including the fiber composition used. In one embodiment, for example, the foam density may be greater than about 200 g / L, such as greater than about 250 g / L, such as greater than about 300 g / L. Foam density is typically 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 example, a lower density foam is used, the foam density of which is typically 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 typically have an air content 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 typically less than about 80% by volume, such as less than about 70% by volume, such as less than about 65% by volume.

[0095] To form a nonwoven fiber web, foam is combined with selected fiber ingredients and any auxiliaries. The foamed fiber suspension is then pumped into a tank and fed from the tank into a headbox. For example, Figure 1 and Figure 2 An embodiment of a process for forming a fiber web according to this disclosure is shown. Figure 2 As specifically shown, the foamed fiber suspension can be fed into tank 312 and then into headbox 310. The foamed fiber suspension flows from headbox 310 onto a ring-moving forming fabric 326 supported and driven by rollers 328 to form a fiber web 210. Figure 2 As shown, the forming plate 314 may be located below the fiber web 210, adjacent to the headbox 310. Once formed on the forming fabric 326, the foam forming fiber web may 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 may be less than about 2%, such as less than about 1.8%, such as less than about 1.5%. The forming consistency is typically greater than about 0.5%, such as greater than about 0.8%. The forming consistency indicates the ability to produce a fiber web according to this disclosure while minimizing the amount of water required during forming.

[0096] Once the wet fiber web is formed on the shaped fabric 326, the web is conveyed downstream and dehydrated. The process may optionally include multiple vacuum devices 316, such as vacuum chambers and vacuum rollers. Vacuum chambers help remove moisture from the newly formed fiber web 210.

[0097] like Figure 2As shown, the formed fabric 326 can also be connected to a steam box 318 located above a pair of vacuum rollers 320. For example, the steam box 318 can increase dryness and reduce transverse moisture variation. Steam applied from the steam box 318 heats the moisture in the wet fiber web 210, making it easier for water to drain from the web, especially in conjunction with the vacuum rollers 320. Figure 1 In the illustrated embodiment, the newly formed fiber web 210 is conveyed downstream from the formed fabric 326, optionally undergoes hydroentangling, and is dried on a ventilated dryer.

[0098] After the foam-formed fiber web has been produced, the fiber web is optionally subjected to one or more hydroentangling steps. Figure 2 In the illustrated implementation, for example, the fiber web 210 undergoes two different hydroentangling steps. Specifically, in Figure 2 In this process, the fiber web 210 is hydroentangled on a first surface during a first hydroentangling step, and then hydroentangled on an opposing second surface during a second hydroentangling step. Figure 2 As shown, for example, the process may include a first hydroentangling device 330 and a second hydroentangling device 332. Hydroentangling occurring at each hydroentangling station can be accomplished using conventional hydroentangling equipment. Hydroentangling of the foam-formed fiber web can be performed using any suitable working fluid, such as water. The working fluid flows through a manifold that uniformly distributes the fluid through a series of individual orifices or openings. For example, exemplary orifices or openings may have a diameter of about 0.003 inches to about 0.015 inches. For example, the manifold may include strips of orifices with a diameter of about 0.007 inches. The manifold may contain about 20 to about 40 orifices per inch and may include 1 to 3 rows of orifices. Many other manifold configurations and combinations can be used. For example, in Figure 2 In the illustrated embodiments, the spunlace device 330 includes a plurality of injectors 334, while the spunlace device 332 includes a plurality of injectors 336. The injectors 334 and 336 may be part of a manifold and may be in communication with a source of working fluid.

[0099] During the hydroentangling process, the working fluid can pass through the orifice at pressures ranging from approximately 200 psig to approximately 3,500 psig. Within the upper limit of the described pressure range, it is conceivable that the fiber web can be processed at speeds from approximately 500 ft / min to approximately 2000 ft / min. The fluid impingement can be supported on a porous surface or wire, or on a porous drum surface of material or fiber web. Figure 2 In the illustrated implementation, for example, hydroentanglement occurs on the first rotating drum 338 and the second rotating drum 340.

[0100] During hydroentangling, the fiber web 210 can be placed directly on the surfaces of the rotating drum 338 and the rotating drum 340. Each rotating drum may include multiple openings or vacuum channels for extracting excess water. These openings or vacuum channels may also form patterns in the fiber web 210 during the hydroentangling process. For example, a pattern may be formed on one surface of the fiber web at a first hydroentangling station, and a pattern may be formed on an opposing second surface of the fiber web at a second hydroentangling station.

[0101] In addition to forming the desired morphology and improving the cleanliness of the nonwoven material 210, one or more hydroentangling stations can significantly improve various physical properties of the fiber web 210, such as the integrity of the fiber web. For example, a columnar jet of working fluid directly impacting the surface of the fiber web is used to entangle and wrap the fibers contained within the fiber web. The hydroentangling process ultimately forms a coherent entangled matrix. The hydroentangling step is also used to further produce a substantially homogeneous fiber mixture within the fiber web. For example, the resulting hydroentangled fiber web is "non-layered" and does not contain distinguishable individual fiber layers in terms of web thickness.

[0102] Once the foam-formed fiber web 210 has been hydroentangled once or multiple times, a non-compression drying process can be used to dry the fiber web. For example, as... Figure 1 As shown, a ventilated dryer can be used to dry foam-molded fiber webs.

[0103] refer to Figure 1 The foam-formed and hydroentangled fiber web 210 is transferred from the drum 340 to the penetrating dry fabric 344 by means of a vacuum transfer roller 346 or a vacuum transfer shoe. If desired, the penetrating dry fabric can run at a slower speed than the fiber web 210 to further enhance stretch. The transfer can be performed with vacuum assistance to ensure that the sheet deforms to conform to the penetrating dry fabric, thereby producing the desired volume and appearance (if desired).

[0104] exist Figure 1 In the illustrated embodiment, the foam-formed fiber web 210 is transferred to the penetrating dryer fabric 344. Alternatively, the foam-formed fiber web may be transferred to a porous metal sleeve forming the circumference of the penetrating dryer 348. Using a metal sleeve instead of fabric can provide various advantages. For example, the porous metal sleeve can also create porosity to increase the liquid absorption properties of the fiber web.

[0105] Alternatively, the foam-formed fiber web 210 may be conveyed on a penetrating dry fabric 344 on the circumference of the penetrating dryer 348.

[0106] The vacuum level used for transferring the web can be from about 3 inches to about 15 inches of mercury (75 mm to about 380 mmHg), preferably about 5 inches (125 mm) of mercury. In addition to or as an alternative to using a vacuum to draw the web onto the next fabric, a vacuum shoe or roller (negative pressure) can be supplemented or replaced by using positive pressure from the opposite side of the web to blow the web onto the next fabric.

[0107] Finally, the fiber web is dried to approximately 94% or higher consistency via a penetration dryer 348 and then transferred to carrier fabric 350. The dried substrate 352 is conveyed to a reel 354 using carrier fabric 350 and optionally carrier fabric 356. Optional pressure guide rollers 358 can be used to facilitate the transfer of the fiber web from carrier fabric 350 to fabric 356. Suitable carrier fabrics for this purpose are Albany International 84M or 94M and Asten 959 or 937, all of which are relatively smooth fabrics with fine patterns.

[0108] Nonwoven materials can be thermally bonded, either as an alternative to or in addition to spunlace nonwoven materials. Thermal bonding can be achieved using heat and pressure or by applying ultrasonic energy.

[0109] In one respect, nonwoven materials can undergo hot spot bonding. As an example, hot spot bonding typically involves passing a nonwoven material containing fibers to be bonded through the gap between a pair of heated bonding calendering rollers. One of the bonding rollers is typically (but not always) patterned in a way that the entire material does not bond across its entire surface, and the second roller, or support roller, is typically a smooth surface. Therefore, various patterns have been developed for the calendering rollers for both functional and aesthetic reasons. One example of a pattern has dots and is the Hansen Pennings or “H&P” pattern, which has approximately 30% of the bonded area and approximately 200 bonded portions per square inch, as taught in U.S. Patent 3,855,046 to Hansen and Pennings. The resulting pattern has approximately 29.5% of the bonded area. Another typical dot bonding pattern is the extended Hansen Pennings or “EHP” bonding pattern, which produces 15% of the bonded area. Another common pattern is the C-Star pattern, which has approximately 16.9% of the bonded area. The C-Star pattern features horizontal stripes interrupted by shooting stars or a "corduroy" design. Other common patterns include diamond patterns with repeating and slightly offset rhombuses, having approximately 16% of the bonded area, and yarn-woven patterns with roughly alternating vertical segments, having approximately 19% of the bonded area. Typically, the percentage of bonded area varies between approximately 10% and approximately 30% of the nonwoven material area.

[0110] The method disclosed herein can produce fiber webs with good volumetric properties. For example, the volume is typically greater than about 3 cc / g, such as greater than about 5 cc / g, such as greater than about 8 cc / g, such as greater than about 10 cc / g, such as greater than about 12 cc / g, and typically less than about 20 cc / g, such as less than about 15 cc / g. The nonwoven fiber web can also exhibit an enhanced thickness per basis weight greater than about 0.009 mm / gsm, such as greater than about 0.010 mm / gsm, such as greater than about 0.011 mm / gsm. For example, at a basis weight of about 55 gsm to about 70 gsm, the thickness of the substrate can be greater than about 0.4 mm, such as greater than about 0.5 mm, such as greater than about 0.6 mm and less than about 3 mm.

[0111] exist Figure 2 and Figure 3 In the illustrated embodiments, the foam-formed fiber web can be hydroentangled on a patterned forming surface to form a pattern of raised elements. However, in other embodiments, suction positioned below the forming surface can be used to form the raised elements. These methods produce raised elements with an increased basis weight compared to the base surface of the fiber web. Texture can also be imparted to the fiber web by embossing. However, when the fiber web is embossed, the basis weight of the fiber web remains uniform and no raised elements with increased basis weight are produced.

[0112] Nonwoven fiber webs manufactured according to this disclosure may typically have a smooth surface or may include a pattern of raised elements based on hydroentangling conditions.

[0113] When tested at a pressure of 0.05 psi, the nonwoven material manufactured according to this disclosure typically exhibits a strength greater than about 0.08 g / cm³. 3 The density. For example, the density of a nonwoven fiber web can be greater than about 0.1 g / cm³. 3 And less than approximately 2g / cm 3 Such as less than about 1.8 g / cm³ 3 Such as less than about 0.14 g / cm 3 .

[0114] The basis weight of the nonwoven material manufactured according to this disclosure can be any value from about 20 gsm to about 200 gsm, including all increments of 1 gsm therebetween. In one aspect, the basis weight can be less than about 100 gsm, such as less than about 90 gsm, such as less than about 80 gsm, such as less than about 70 gsm, such as less than about 68 gsm, such as less than about 65 gsm. The basis weight is typically greater than about 40 gsm, such as greater than about 50 gsm, such as greater than about 52 gsm, such as greater than about 55 gsm, such as greater than about 58 gsm.

[0115] As described above, nonwoven fiber webs manufactured according to this disclosure typically comprise cellulose pulp fibers combined with microfibers. In one aspect, the cellulose pulp fibers and microfibers essentially constitute all the fibers contained in the nonwoven fiber web. For example, the cellulose pulp fibers and microfibers may account for more than about 90% by weight, such as more than about 95% by weight, or such as more than about 98% by weight of the fibers contained in the nonwoven fiber web. In this respect, the nonwoven fiber web may be configured not to contain any other synthetic polymer short fibers, such as bonding fibers, etc.

[0116] The nonwoven materials manufactured according to this disclosure can be used in many different products and applications. In one aspect, the nonwoven fiber web can be used as a wiping material, in its stylistically. For example, see reference... Figure 3 The diagram shows a spiral wound product 10 according to the present disclosure. The spiral wound product 10 is composed of individual sheets separated by perforated lines 12.

[0117] Alternatively, the nonwoven materials disclosed herein may be cut into individual sheets and sold in stacks. For example, as Figure 4 As shown, a stack 20 of individual sheets is illustrated. In one embodiment, the individual sheets may be folded in an interlaced manner as shown.

[0118] In other embodiments, the nonwoven materials of this disclosure can be incorporated into products and used as layers within products. For example, nonwoven fiber webs can be incorporated into personal care products, such as absorbent articles, including diapers, pull-ups, incontinence products, feminine hygiene products, etc.

[0119] The present disclosure can be better understood by referring to the following embodiments.

[0120] Example

[0121] The following examples illustrate some of the advantages and benefits of this disclosure.

[0122] According to this disclosure, a foam-formed substrate is produced comprising a combination of cellulose pulp fibers and microfibers. The cellulose pulp fibers include southern cork kraft paper fibers. Two different nonwoven materials are manufactured according to this disclosure. A first nonwoven material contains microfibers with a size of 0.5 denier (sample number 1). A second nonwoven material contains microfibers with a size of 1.5 denier (sample number 2). Each microfiber comprises polyester fibers with an average length of 12 mm. Each nonwoven material contains 80% by weight of cellulose pulp fibers and 20% by weight of microfibers. Each nonwoven material has a basis weight of 60 gsm.

[0123] Nonwoven materials are manufactured using a foam forming process, which includes processes similar to... Figure 1 and Figure 2 The hydroentangling step of the process is illustrated in the figure.

[0124] The nonwoven material was subjected to various tests, and the following results were obtained:

[0125] Table 1

[0126] Sample No. 1 Sample No. 2 Adjusting the basis weight [g / m^2] 62.8 60.7 Oven-dry basis weight [g / m^2] 59.9 57.9 Thickness of one sheet of tissue paper [mm] 0.501 0.670 Density, g / cc 0.122 0.086 Thickness of nonwoven materials [mm] 0.694 0.794 Nonwoven density, g / cc 0.086 0.073 Rupture strength, maximum peak load [gf] 5914 3384 Fracture strength, maximum energy at peak load [g*cm] 5301 2884 Breaking strength, maximum peak elongation [mm] 23.3 21.2 Strip stretching, dry transverse peak load / sheet [gf] 5082 2782 Strip stretching, dry transverse peak elongation [%) 44.36 30.31 Strip stretching, dry transverse tensile strength at 500g [%] 3.003 2.391 Strip tension and fracture dry transverse TEA / sheet [gf*cm / cm^2) 227.7 92.9 Strip stretching, dry transverse slope A / sheet [kgf] 20.1 21.1 Strip stretching, dry longitudinal peak load / sheet [gf] 9574 5170 Strip stretching, dry longitudinal peak elongation [%) 21.81 18.36 Strip stretching, dry longitudinal tensile strength at 500g [%] 0.395 0.517 Strip stretching, dry longitudinal TEA / sheet at fracture [gf*cm / cm^2) 274.1 134.7 Strip stretching, dry longitudinal slope A / sheet [kgf] 69.8 68.5 Strip stretching, wet longitudinal peak load / sheet [gf] 3406 1624 Strip tension, wet transverse peak load / sheet [gf] 5653 2540 GMT, dry peak load 6975 3793 GMT, wet peak load 4388 2031 Trapezoidal tear, dry transverse peak load and first peak average [gf] 1542.2 529.6 Trapezoidal tear, dry longitudinal peak load and average of the first peak [gf] 2262.8 1085.5 Trapezoidal tear, wet transverse peak load, and average value of the first peak [gf] 1103.8 364.3 Trapezoidal tear, wet longitudinal peak load, and average value of the first peak [gf] 1889.8 555.7

[0127] Table 2

[0128] Sample No. 1 Sample No. 2 Abrasion resistance, highest dryness, highest edge [cycle]. 55.93 12.67 Abrasion resistance, highest wet edge [cycle]. 43.80 15.67 For pilling resistance, Gelbo achieves a maximum transverse thickness of 5.0 [μm]. 39.73 27.33 For pilling resistance, Gelbo achieves a maximum transverse thickness of 10.0 [μm]. 16.67 8.40 Resistant to pilling, Gelbo has a maximum transverse thickness of 20.0 [μm]. 4.53 1.80 For pilling resistance, Gelbo achieves a maximum transverse thickness of 50.0 [μm]. 0.93 0.33 For pilling resistance, Gelbo achieves a maximum transverse thickness of 75.0 [μm]. 0.13 0.13 For pilling resistance, Gelbo achieves a maximum transverse thickness of 99.9 [μm]. 0.13 0.20 For pilling resistance, Gelbo has a maximum transverse thickness of ≥5.0 [μm]. 62.13 38.20 Resistant to pilling, Gelbo's transverse thickness is ≥10.0 [μm]. 22.40 10.87 Resistant to pilling, Gelbo's transverse thickness is ≥20.0 [μm]. 5.73 2.47 Resistant to pilling, Gelbo's transverse thickness is ≥50.0 [μm]. 1.20 0.67 For pilling resistance, Gelbo has a maximum transverse thickness of ≥75.0 [μm]. 0.27 0.33 For pilling resistance, Gelbo achieves a maximum transverse thickness of ≥99.9 [μm]. 0.13 0.20 Resistant to pilling, Gelbo achieves a maximum longitudinal thickness of 5.0 [μm]. 44.00 25.47 Resistant to pilling, Gelbo achieves a maximum longitudinal thickness of 10.0 [μm]. 14.87 6.60 Resistant to pilling, Gelbo achieves a maximum longitudinal thickness of 20.0 [μm]. 6.20 1.53 Resistant to pilling, Gelbo longitudinal thickness up to 50.0 [μm] 1.20 0.40 For pilling resistance, Gelbo achieves a maximum longitudinal thickness of 75.0 [μm]. 0.27 0.13 For pilling resistance, Gelbo achieves a maximum longitudinal thickness of 99.9 [μm]. 0.40 0.20 Resistant to pilling, Gelbo longitudinal thickness ≥5.0 [μm] 66.93 34.33 Resistant to pilling, Gelbo longitudinal thickness ≥10.0 [μm] 22.93 8.87 Resistant to pilling, Gelbo longitudinal thickness ≥20.0 [μm] 8.07 2.27 Resistant to pilling, Gelbo longitudinal thickness ≥50.0 [μm] 1.87 0.73 For pilling resistance, Gelbo achieves a maximum longitudinal thickness of ≥75.0 [μm]. 0.67 0.33 For pilling resistance, Gelbo achieves a maximum longitudinal thickness of ≥99.9 [μm]. 0.40 0.20

[0129] As shown above, the nonwoven material exhibits unexpectedly high strength and durability properties when containing only 20% by weight of microfiber. These significantly improved strength properties were demonstrated in both wet and dry conditions. The samples also exhibited excellent tear properties while being virtually fuzz-free.

[0130] Sample No. 1, containing 0.5 denier fibers, contains more than approximately 30,000,000 microfibers / m. 2 Such as more than approximately 35,000,000 microfibers / m 2 Sample number 1 also contained more than approximately 300,000 linear meters of ultrafine fibers / m. 2 Sample number 2 contains more than approximately 3,000,000 microfibers / m. 2 It contains more than approximately 60,000 linear meters of ultrafine fibers per m 2 .

[0131] The ability of nonwoven materials to absorb liquids was also tested, and the following results were obtained:

[0132] Table 3

[0133] Sample No. 1 Sample No. 2 Absorption capacity, water, specific capacity [g / g] 6.75 7.01 Absorption capacity, SAE30, specific capacity [g / g] 7.93 8.29 Absorption capacity, level of saturation and excretion, specific capacity [g / g] 8.58 9.19 Vertical wicking rate at 15 seconds, horizontal rate, deionized water [cm] 4.17 4.37 Vertical wicking rate at 30 seconds, lateral rate, deionized water [cm] 5.31 5.55 Vertical wicking rate at 45 seconds, lateral, deionized water [cm] 6.18 6.43 Vertical wicking rate at 60 seconds, lateral, deionized water [cm] 6.92 7.01 Vertical wicking rate at 15 seconds, longitudinal direction, deionized water [cm] 4.89 5.21 Vertical wicking rate at 30 seconds, longitudinal direction, deionized water [cm] 6.13 6.41 Vertical wicking rate at 45 seconds, longitudinal direction, deionized water [cm] 7.20 7.44 Vertical wicking rate at 60 seconds, longitudinal direction, deionized water [cm] 8.01 8.22

[0134] It is believed that the reduction in the fiber-to-basic weight ratio creates a larger void space within the structure, which explains the aforementioned extremely high wicking rate and absorption capacity.

[0135] The tribological properties of the nonwoven fiber web were also tested, and the following results were obtained:

[0136] Table 4

[0137] Sample No. 1 Sample No. 2 COF: Dry; Lateral; Peak static load [gf] 88.2 91.9 COF: Dry; Lateral; Maximum Average Dynamic Load [gf] 73.2 79.3 COF: Dry: Longitudinal: Peak static load [gf] 100.8 106.2 COF: Dry: Longitudinal: Maximum average dynamic load [gf] 79.9 92.2 COF: Wet: Lateral: Peak static load [gf] 222.7 235.3 COF: Moisture: Lateral: Maximum average dynamic load [gf] 207.8 268.6 COF: Moisture: Longitudinal: Peak static load [gf] 232.5 235.9 COF: Moisture: Longitudinal: Maximum average dynamic load [gf] 241.2 282.0

[0138] These and other modifications and variations of the invention can be practiced by those skilled in the art without departing from the spirit and scope of the invention, which are more specifically set forth in the appended claims. Furthermore, it should be understood that aspects of the various embodiments are interchangeable in whole or in part. Moreover, those skilled in the art will understand that the foregoing description is merely illustrative and is not intended to limit the invention further described in the appended claims.

Claims

1. A nonwoven product, said nonwoven product comprising: A nonwoven fiber web comprising microfibers blended with cellulose pulp fibers, the microfibers having an average length greater than about 8 mm and a fiber size less than about 1.8 denier, the microfibers comprising synthetic polymer fibers or regenerated cellulose fibers; The fiber web has a basis weight of less than 100 gsm; and The nonwoven fiber web contains more than about 2,800,000 fibers / m. 2 The amount of the ultrafine fibers.

2. The nonwoven product according to claim 1, wherein the microfiber has a linear density greater than 50,000 linear meters / m 2 Such as greater than approximately 100,000 linear meters / m 2 Such as greater than approximately 150,000 linear meters / m 2 Such as greater than approximately 200,000 linear meters / m 2、 Such as greater than approximately 300,000 linear meters / m 2 Such as greater than approximately 400,000 linear meters / m 2 Such as greater than approximately 500,000 linear meters / m 2 And less than approximately 1,500,000 linear meters / m 2 The amount is contained in the nonwoven fiber web.

3. The nonwoven product according to any one of the preceding claims, wherein the microfiber has a density of more than about 5,000,000 fibers / m. 2 Such as greater than approximately 10,000,000 fibers / m 2 Such as greater than approximately 20,000,000 fibers / m 2 Such as greater than approximately 30,000,000 fibers / m 2 Such as greater than approximately 40,000,000 fibers / m 2 Such as greater than approximately 50,000,000 fibers / m 2 Such as greater than approximately 60,000,000 fibers / m 2 The amount is contained in the nonwoven fiber web.

4. The nonwoven product according to any one of the preceding claims, wherein the nonwoven fiber web exhibits a value greater than about 0.07 g / cm³. 3 Such as greater than approximately 0.09 g / cm³ 3 Such as greater than about 0.1 g / cm 3 Such as greater than approximately 0.11 g / cm³ 3 The density.

5. The nonwoven product according to any one of the preceding claims, wherein the nonwoven fiber web exhibits a longitudinal tensile strength greater than about 5000 gf, such as greater than about 6000 gf, such as greater than about 7000 gf, such as greater than about 8000 gf, such as greater than about 9000 gf, and less than about 20,000 gf, and exhibits a transverse tensile strength greater than about 2500 gf, such as greater than about 3000 gf, such as greater than about 3500 gf, such as greater than about 4000 gf, such as greater than about 4500 gf, and less than about 10,000 gf.

6. The nonwoven product according to any one of the preceding claims, wherein the nonwoven fiber web exhibits a longitudinal wet tensile strength greater than about 2500 gf, such as greater than about 3500 gf, such as greater than about 4000 gf, such as greater than about 4500 gf, such as greater than about 5000 gf, such as greater than about 5500 gf, and less than about 12,000 gf, and exhibits a transverse wet tensile strength greater than about 1500 gf, such as greater than about 2000 gf, such as greater than about 2500 gf, such as greater than about 3000 gf, such as greater than about 3200 gf, and less than about 10,000 gf.

7. The nonwoven product according to any one of the preceding claims, wherein the nonwoven fiber web exhibits a longitudinal trapezoidal tear strength greater than about 1000 gf, such as greater than about 1500 gf, such as greater than about 2000 gf, such as greater than about 2200 gf, and less than about 6,000 gf, and exhibits a transverse trapezoidal tear strength greater than about 500 gf, such as greater than about 1000 gf, such as greater than about 1500 gf, and less than about 5,000 gf.

8. The nonwoven product according to any one of the preceding claims, wherein the fiber web comprises a foam-formed fiber web.

9. The nonwoven product according to any one of the preceding claims, wherein the fiber web has been hydroentangled and / or thermally bonded.

10. The nonwoven product according to any one of the preceding claims, wherein the microfiber comprises polyester fiber.

11. The nonwoven product according to any one of claims 1 to 9, wherein the microfiber comprises polyolefin fiber.

12. The nonwoven product according to any one of claims 1 to 9, wherein the microfiber comprises regenerated cellulose fiber.

13. The nonwoven product according to any one of the preceding claims, wherein the microfiber comprises crimped fibers.

14. The nonwoven product according to any one of the preceding claims, wherein the microfiber has a fiber size of less than about 1 denier, such as less than about 0.8 denier, such as less than about 0.6 denier and greater than about 0.25 denier.

15. The nonwoven product according to any one of the preceding claims, wherein the microfiber has an average fiber length greater than about 10 mm, such as greater than about 11 mm, and less than about 20 mm.

16. The nonwoven product according to any one of the preceding claims, wherein the microfiber is present in the fiber web in an amount of 10% to about 50% by weight, such as about 15% to about 25% by weight, and wherein the nonwoven fiber web has a basis weight of about 40 gsm to about 70 gsm, such as about 52 gsm to about 68 gsm.

17. The nonwoven product according to any one of the preceding claims, wherein the foam-formed fiber web has a first surface and an opposing second surface, and wherein the first surface has been hydroentangled, and the second surface has been hydroentangled.

18. The nonwoven product according to any one of the preceding claims, wherein the foam-formed fiber web is a single-layer sheet fiber web and is non-layered.

19. The nonwoven product according to any one of the preceding claims, wherein the nonwoven fiber web contains a foaming agent.

20. The nonwoven product according to claim 19, wherein the foaming agent comprises lauryl sulfate, glycoside, sodium lauryl sulfate, ammonium lauryl sulfate, fatty acid amine, amide, amine oxide, or fatty acid quaternary compound.

21. The nonwoven product according to any one of the preceding claims, wherein the nonwoven product includes industrial wipes.

22. The nonwoven product of claim 21, wherein the industrial wipe comprises a plurality of individual sheets stacked together or comprises a spirally wound product.

23. The nonwoven product according to any one of the preceding claims, wherein the nonwoven product is pre-saturated with a clean solvent.

24. A nonwoven product, said nonwoven product comprising: A nonwoven fiber web comprising ultrafine synthetic polymer fibers blended with cellulose pulp fibers, the ultrafine synthetic fibers having an average length greater than about 8 mm and a fiber size less than about 0.8 denier, the ultrafine synthetic polymer fibers being present in the nonwoven fiber web in an amount of about 10% to about 50% by weight.

25. The nonwoven product of claim 24, wherein the ultrafine synthetic polymer fiber comprises crimped fiber.

26. A nonwoven product, said nonwoven product comprising: A nonwoven fiber web comprising ultrafine synthetic fibers blended with cellulose pulp fibers, the ultrafine synthetic fibers having an average length greater than about 8 mm and a fiber size less than about 0.8 denier, and wherein the nonwoven fiber web exhibits a longitudinal tensile strength greater than about 7000 gf, a transverse tensile strength greater than about 3500 gf, a longitudinal wet tensile strength greater than about 4000 gf, a transverse wet tensile strength greater than about 2500 gf, a longitudinal trapezoidal tear strength greater than about 2000 gf, and a transverse trapezoidal tear strength greater than about 1500 gf, and wherein the nonwoven fiber web has a basis weight of about 45 gsm to about 70 gsm.

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