• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    FABRIC SHEETS WITH REINFORCED CROSS PROPERTIES. The present description presents continuous sheets with greater durability, produced by rewetting a continuous sheet, pressing it and drying it a second time. This improved durability is manifested by a high transverse inclination of the machine (CD).
    公开号:BR112014015393B1
    申请号:R112014015393-0
    申请日:2012-11-27
    公开日:2021-02-02
    发明作者:Michael Alan Hermans；Rachel Allison Graff；Samuel August Nelson
    申请人:Kimberly-Clark Worldwide, Inc；
    IPC主号:
    专利说明:

    HISTORIC
    [1] In general, paper manufacturers, especially manufacturers of low-weight fabric wefts, have attempted to reduce machine and transverse slopes at a given tensile strength. For example, U.S. Patent No. 7,972,474 for Underhill discloses fabrics with reinforced properties of transversal direction to the machine, including a relatively high peak stretch capacity, relatively low slope and energy absorbed in the traction. Underhill reported that fabric products with these properties have a relatively low stiffness with greater extensibility at relatively high levels of strength. In general, products manufactured in Underhill had an inclination in the transverse direction of the machine (inclination CD) of about 2,000 to 3,000 grams per 3 inches. Underhill formulated the hypothesis that the CD inclination correlates with low flexural stiffness, producing a soft tissue.
    [2] In addition to Underhill's teachings, paper manufacturers have attempted to reduce CD skew by reducing CD tensile strength, or by increasing CD stretch in CD traction. However, as the increase in CD stretch levels became practical due to advances in fabric technology, the CD slope values became even lower, and at some point, a low CD slope can be interpreted indicative of a fabric. weak or "fragile". Thus, in some cases, it may be desirable for the paper manufacturer to increase the CD slope.
    [3] An example of increasing the CD slope of a fabric web is provided in U.S. Patent No. 7,300,543 for Mullally. To increase the CD inclination of the fabric weave, Mullally used papermaking fabrics with deep, discontinuous pockets in a non-curled, direct-drying fabric process. While Mullally's fabric wefts increased the CD slope, these CD slope values may not be sufficient to provide a fabric with desired levels of attributes such as substance in hand at the appropriate CD traction level. In addition, a product with discontinuous pockets cannot be desired by consumers. Therefore, there remains a need in the art for fabric weaves with increased CD slope, as well as methods of fabricating them. ABSTRACT
    [4] It has been found that fabric weaves with greater durability and smoothness can be produced by rewetting a dry fabric weave, pressing the fabric again wet and drying it a second time. This improved durability / smoothness ratio is manifested by a greater inclination in the transverse direction (inclination CD), which is the load inclination of the machine's transverse direction in relation to the fabric elongation curve. The high CD slope, particularly at a given level of CD traction and CD stretch, gives rise to products that tend to be perceived by the consumer as durable. In addition, a high CD slope means that the beneficial CD stretch is not easily removed from the fabric when the product is used by the consumer. Therefore, fabric products with a high CD pitch will resist removal of the CD stretch when subjected to a transverse tensile load. The CD properties are particularly important, as the fabric wefts are, in general, relatively weak and fail in this direction due to the orientation of the fibers, mainly in the direction of the machine (MD). And so, increasing the CD slope is highly desirable to provide an exceptionally durable fabric. Although the inclination of the CD can only be increased by increasing the tensile strength of the CD, this is not preferred, as it tends to make the fabric more rigid and, consequently, less soft in the eyes of the consumer. Therefore, an appropriate combination of CD tensile strength and CD tilt has been determined to be highly desirable to provide consumer-preferred fabric products.
    [5] Thus, in one aspect, the present description provides a fabric weave with a CD pull of less than about 1,500 grams by 3 inches, a CD stretch greater than about 12 percent, and a CD slope greater than about 9,000 grams by 3 inches.
    [6] In other respects, the present description features a fabric weave with a CD to CD slope ratio greater than about 10 and a CD stretch greater than about 10 percent.
    [7] In another aspect, the present description provides a method of making a woven fabric, comprising: (a) molding a direct drying fabric weave, with a moisture content of less than about 5 percent, (b) rewetting the weft, (c) pressing the rewetted weft, and (d) drying the pressed weft, so that the weft has a moisture content of less than about 5 percent. DESCRIPTION OF THE DRAWINGS
    [8] FIG. 1 is an illustration of an embodiment for the rewetting, pressing and drying of a fabric web according to the present invention;
    [9] FIG. 2a is a top view of the press plate used to press the wefts, as described in the Examples and FIG. 2b is a detailed profile view of it; and
    [10] FIG. 3 is a photograph of the t-1205-2 TAD fabric provided by Voith Fabrics (Appleton, WI). DEFINITIONS
    [11] The terms "tensile strength", "MD traction" and "CD traction" generally refer to the maximum stress that a material can withstand when being stretched or pulled in any orientation, as measured using a crosshead speed. 254 millimeters per minute, a full-scale load of 4,540 grams, a jaw extension (length) of 50.8 millimeters and a sample width of 762 millimeters. MD tensile strength is the peak load per 3 inches of sample width when a sample is pulled towards the machine until it breaks. Similarly, the tensile strength CD represents the peak load per 3 inches of sample width, when a sample is pulled across the machine until it breaks. For products with 1 layer, each measurement of tensile strength is made in 1 layer. For products with multiple layers, the tensile test is made from the expected number of layers in the finished product. For example, products with 2 layers are tested two layers at a time, where the tensile strengths MD and CD recorded are the strengths of both layers.
    [12] The samples for the tensile strength test are prepared by cutting a strip of 3 inches (76.2 millimeters) x 5 inches (127 millimeters) in length either in the machine direction (MD) or transverse machine direction (CD ), using a JDC Precision precision sample cutter (Thwing-Albert Instrument Company, Philadelphia, PA, Model No. 3-10 JDC, No. 37333). The instrument used to measure the tensile strength is an MTS Systems Sintech 11S, N °. series 6233. The data acquisition software is MTS TestWorks TM for Windows Ver. 3.10 (MTS Systems Corp, Research Triangle Park, NC). The load cell is selected from either 50 Newton or 100 Newton maximum, depending on the resistance of the sample to be tested, so that most peak load values fall between 10 and 90 percent of the scale value load cell. The length between the jaws is 2 ± 0.04 inches (50.8 ± 1 mm). The jaws are operated using pneumatic action and coated in rubber. The minimum width of the clamping face is 3 inches (76.2 mm), and the approximate height of a clamp is 0.5 inches (12.7 mm). The crosshead speed is 10 ± 0.4 inches / min (254 ± 1 mm / min), and the burst sensitivity has been fixed at 65 percent. The sample is placed on the instrument's jaws, centered both vertically and horizontally. The test starts and ends when the sample breaks. The peak load is recorded as "tensile strength MD" or "tensile strength CD" of the sample, depending on the sample being tested. At least six (6) representative specimens are tested for each product, taken "as is", and the arithmetic mean of all individual sample tests is the MD or CD tensile strength of the product.
    [13] The term "energy absorbed in traction" (abbreviated "TEA") generally refers to the area under the stress-strain curve during the same tensile test, as described above. The area is based on the strain value achieved when the fabric is forced to rupture and the load placed on the fabric has dropped to 65 percent of the peak stress load. Since the thickness of a paper tissue is generally unknown and varies during testing, it is common practice to ignore the cross-sectional area of the tissue and report the "tension" on the tissue as a charge per unit length or, typically, in grams units by 3 inches wide. For the TEA calculation, the tension is converted to grams per centimeter and the area is calculated by integration. The deformation units are centimeter by centimeter, so that the final TEA units become g-cm / cm2.
    [14] The terms "stretch", "MD stretch" and "CD stretch" generally refer to the ratio between the elongation corrected by the gap in a sample, at the point where it generates its peak load, divided by the length corrected by the gap in any orientation. Stretching is an output of MTS TestWorks ™ in determining tensile strength, as described above. The stretch is presented as a percentage (%).
    [15] The term "CD slope" generally refers to the slope of the line resulting from the graphical representation of CD traction versus CD stretching slope of the line resulting from CD traction versus CD stretching and is an output of MTS TestWorks ™ in determining resistance to traction as described above. The slope is reported in units of grams (g) per unit width of the sample (inches), and is measured as the slope of the least squares line adjusted to the stretch points rectified by the load, falling between a force generated by the sample of 70 at 157 grams (0.687 to 1.540 N) divided by the width of the sample.
    [16] As used herein, the "gauge" of the fabric is the representative thickness of a single fabric measured according to TAPPI T402 test methods "Standard Conditioning and Testing Atmosphere For Paper, Board, Pulp Handsheets and Related Products" and T411 om-89 "Thickness (caliper) of Paper, Paperboard, and Combined Board" with note 3 for stacked fabrics. The micrometer used for the T411 tests om-89 is an Emveco 200-A fabric gauge tester (Emveco , Inc., Newberg, OR) .The micrometer has a load of 2 kilos-pascals, a foot pressure area of 2500 square mm and a pressure pedal diameter of 56.42 mm, a pause time of 3 seconds and a reduction rate of 0.8 millimeter per second.
    [17] As used herein, the "volume" of tissues is calculated as the quotient between the "caliber", expressed in microns, divided by the dry basic weight, expressed in grams per square meter. The resulting tissue volume is expressed in cubic centimeters per gram.
    [18] As used herein, the term "fabric moisture" generally refers to the average fabric moisture for a 10-foot fabric segment of fabric. The moisture of the fabric is by weighing the fabric containing moisture and comparing the weight of this fabric with the weight of a fabric after drying it in an oven, until the total moisture is removed. A suitable test method for determining tissue moisture is the T-210 cm 93 TAPPI Test. DETAILED DESCRIPTION
    [19] It was with surprise that it was discovered that a fabric web with reinforced cross-machine properties (CD), such as the CD slope and CD stretch, can be produced by subjecting a fabric web to rewetting, pressing and drying by a second time. For example, in one embodiment, a fabric web may be produced according to methods known in the art, such as those disclosed in U.S. Patent No. 5,772,845, to produce an air-dried non-frizzy fabric web ( "UCTAD") with a basic weight of about 15 to about 60 grams per square meter (gsm) and a moisture content of about 0.5 to about 5 percent. The dry fabric web is then rewetted in such a way that the moisture content is increased by at least about 10 percent, preferably from about 15 to about 50 percent. The rewetted fabric web is then subjected to pressure, preferably to a pressure of at least about 1,000 pounds per square inch (psi), as from 2000 to about 10,000 psi. After pressing, the rewetted and pressed fabric web is dried a second time to obtain a fabric web with a moisture content of about 0.5 to about 5 percent, and more preferably, about 1 to about 3 percent. The resulting fabric web has improved CD properties.
    [20] Therefore, in certain embodiments, the rewetted and pressed fabric web may have a CD stretch greater than about 10 percent, more specifically about 12 to about 25 percent, more specifically about from 12 to about 20 percent, more specifically from about 12 to about 18 percent.
    [21] The CD slope of the fabric threads of this invention, which are indicative of the softness or stiffness of the fabric, can be from about 9,000 to about 18,000 grams per 3 inches, more specifically from about 10,000 to about 16,000 grams per 3 inches, and even more specifically about 12,000 to about 14,000 grams per 3 inches. Preferably, the CD slope is achieved in fabric webs with a CD pull of less than about 1,500 grams per 3 inches, and more preferably, from about 800 to about 1,000 grams per 3 inches. As noted earlier, the CD slope can be increased by increasing the CD traction, but with negative effects on stiffness and smoothness. Consequently, one of the objectives of the present invention is to provide a fabric weave that has a relatively modest CD pull, preserving the smoothness of the fabric, but with a high CD pitch.
    [22] The TEA CD of the fabric weaves of the present description, which is indicative of the overall durability of a fabric weave, can be about 8 grams-centimeter per square centimeter (g-cm / cm2) or greater, more specifically from about 8 to about 16 g-cm / cm2, and more specifically from about 10 to about 14 g-cm / cm2.
    [23] In other embodiments, the fabric wefts of the present description have a new combination of CD stretch and CD inclination in a given CD traction. For example, preferably, fabric wefts have a CD draw less than about 1,500 grams per 3 inches, a CD stretch greater than about 12 percent, and a CD slope greater than about 9,000 grams by 3 inches.
    [24] This increase in CD slope at a particular level of CD traction and CD stretch is an improvement over prior art tissues, which typically attempted to reduce the CD slope in a given CD traction. A comparison of fabric weaves produced in accordance with the present description and fabric weaves of the prior art is provided below. TABLE 1

    [25] The fabric wefts made in accordance with the present description can be made with a homogeneous fiber raw material or can be formed from a stratified fiber raw material, producing layers within the single or multiple layer product. The stratified base webs can be formed using equipment known in the art, such as a multi-layer inbox. Both the strength and softness of the base fabric can be adjusted as desired through layered fabrics, such as those produced by the stratified inboxes.
    [26] For example, different fiber raw materials can be used in each layer, to create a layer with the desired characteristics. For example, layers containing softwood fibers have higher tensile strength than layers containing hardwood fibers. Hardwood fibers, on the other hand, can increase the smoothness of the weave. In one embodiment, the single layer base web of the present description includes a first outer layer, and a second outer layer that contains mainly hardwood fibers. The hardwood fibers can be mixed, if desired, with paper decomposed in an amount up to about 10 weight percent, and / or soft wood fibers in an amount up to about 10 weight percent. The base web further includes an intermediate layer positioned between the first outer layer and the second outer layer. The middle layer may contain mainly softwood fibers. If desired, other fibers, such as high-performance fibers or synthetic fibers, can be mixed with the softwood fibers in an amount of up to about 10 weight percent.
    [27] When building the weft from a stratified fiber raw material, the relative weight of each layer may vary, depending on the particular application. For example, in one embodiment, when building a weave containing three layers, each layer can be from about 15 to about 40 percent of the total weight of the weave, such as from about 25 to about 35 percent of the weft weight.
    [28] Wet strength resins can be added to the raw material as desired to increase the wet strength of the final product. Currently, the most widely used wet strength resins belong to the class of polymers called polyamide-polyamine epichlorohydrin resins. There are many commercial suppliers of these types of resins including Hercules, Inc. (Kymene ™), Henkel Corp. (Fibrabond ™), Borden Chemical (Cascamide ™), Georgia-Pacific Corp. and others. These polymers are characterized by having a polyamide structure containing reactive cross-linking groups distributed throughout the structure. Other useful wet resistance agents are marketed by American Cyanamid, under the trade name Parez ™.
    [29] Likewise, resins resistant to the dry state can be added to the raw material as desired to increase the dry state resistance of the final product. These dry-resistant resins include, but are not limited to, carboxymethyl cellulose (CMC), any type of starch, starch derivatives, gums, polyacrylamide resins, and others that are well known. The commercial suppliers of such resins are the same ones that supply the wet-resistant resins discussed above.
    [30] Another resistant chemical that can be added to the raw material is Baystrength 3000 available from Kemira (Atlanta, GA), which is a glyoxalated cationic polyacrylamide used to provide wet and dry tensile strength to fabric wefts .
    [31] As described above, the weft product of the present description can be formed by any variety of papermaking processes known in the art. Preferably, the fabric web is formed by air-drying and can be either curled or non-curled. For example, a papermaking process of the present description can use adhesive curl, wet curl, double curl, embossing, air pressing, air drying, drying and non-curling air, as well as other steps in manufacturing of the paper web. Some examples of such techniques are disclosed in United States Patent No. 5,048,589, 5,399,412, 5,129,988 and 5,494,554, all of which are incorporated herein in a manner consistent with the present description. When manufacturing multi-layered fabric products, the separate layers can be made from the same process or different processes, as desired.
    [32] For example, in one embodiment, the fabric wefts can be air-curled wefts formed by processes known in the art. To form these wefts, a permanent traveling base fabric, properly supported and moved by rollers, receives the paper from the input box. A vacuum box is arranged under the base fabric and is adapted to remove water from the fiber assortment to assist in shaping a weft. From the base weave, a formed weave is transferred to a second weave, which can be a yarn or felt. The fabric is supported for movement around a continuous feature by several guide rollers. A pickup roller designed to facilitate the transfer of the weave from one fabric to another to be included for transferring the weave.
    [33] Preferably, the web formed is dried by transferring to the surface of a heated drying drum, such as a Yankee dryer. The weft can be transferred to the Yankee directly from a dry fabric or, preferably, transferred to a printing fabric, which is used to transfer the weft to the Yankee dryer. According to the present description, the curled composition of the present description can be applied topically to the fabric web, while the web travels over the fabric or can be applied to the surface of the dryer drum for transfer to one side of the web of the dryer. tissue. In this way, the curled composition is used to adhere the fabric web to the drying drum. In this embodiment, as the web is transported through part of the rotation path, heat is transmitted to the web, causing much of the moisture contained in the web to evaporate. The weft is removed from the drum dryer drum by a curling blade. The curling weave that is formed further reduces the internal bond within the weave and increases smoothness. The application of the curled composition to the weft during curling, on the other hand, can increase the weft resistance.
    [34] In another embodiment, the formed web is transferred to the surface of the rotary drum dryer, which can be a Yankee dryer. The pressure rollers may, in one embodiment, comprise a suction pressure cylinder. To adhere the weft to the surface of the dryer drum, a curling adhesive can be applied to the surface of the dryer drum using a sprayer. The sprayer can emit a curling composition made in accordance with the present description or it can emit a conventional curling adhesive. The weft is glued to the surface of the dryer drum and then curled into the drum using the curling blade. If so, the dryer drum can be associated with a hood. The hood can be used to force air against or through the weft. Once curled in the dryer drum, the weft can optionally be fed around a winding drum for cooling and cooled before being wound and a bobbin.
    [35] In addition to applying the crimping composition during molding the fibrous web, the crimping composition can also be used in post-molding processes. For example, in one aspect, the curled composition can be used during a print curling process. Specifically, once applied topically to a fibrous web, the crimped composition was found to be quite suitable for promoting the adhesion of the fibrous web to a crimping surface, such as in a crimping operation by printing.
    [36] For example, once a fiber web is formed and dried, the curl composition can be applied to at least one side of the web and at least one side of the web can then be curled. In general, the curl composition can be applied to only one side of the weft and only one side of the weft can be curled, the curling composition can be applied to both sides of the weft and only one side of the weft is curled, or the curl composition can be applied to each side of the weft and each side of the weft can be curled.
    [37] Once the fabric weave is curled, it can be pulled into a drying station. The drying station can include any form of heating unit, such as an oven powered by infrared heat, microwave energy, hot air or the like. A drying station may be required in some applications to dry the weft and / or cure the curling composition. Depending on the selected curling composition, a drying station may not be necessary.
    [38] In other embodiments, the base web is formed by a non-curled air drying process, described in U.S. Patent No. 5,656,132 and 6,017,417, both of which are incorporated herein by reference in a manner consistent with the present description. A double-screen fabric former with an inbox injects or deposits a raw material from an aqueous suspension of paper-making fibers into various molding fabrics, such as the external forming fabric and the internal forming fabric, and thus forming a weave of damp fabric. The molding process of the present description can be any conventional molding process known in the papermaking industry. Such molding processes include, but are not limited to, Fourdriniers, roof formers, such as suction roll formers, gap formers, such as double wire formers and "crescent" formers.
    [39] The wet fabric web forms on the internal forming screen as it rotates around a molding roll. the internal forming screen serves as a support and carries the newly formed wet fabric web down in the process, as the water is partially removed from the wet fabric web. Additional dehydration of the wet fabric web can be done by known paper-making techniques, such as vacuum suction boxes, while the internal forming fabric supports the wet fabric web. The wet fabric web can be further dehydrated to a consistency of at least about 20 percent, more specifically between about 20 to about 40 percent, and more specifically about 20 to about 30 percent.
    [40] The forming screen can be made of any suitable porous material, such as metal wires or polymeric filaments. For example, some suitable fabrics may include, but are not limited to, Albany 84M and 94M available from Albany International (Albany, NY) Asten 856, 866, 867, 892, 934, 939, 959, or 937; Asten Synweve Model 274, all available from Asten Forming Fabrics, Inc. (Appleton, WI); and Voith 2164 available from Voith Fabrics (Appleton, WI). Molding fabrics or felts comprising non-woven base layers can also be useful, including those from Scapa Corporation made with extruded polyurethane foams, such as the Spectra Series.
    [41] The wet weft is transferred from the forming fabric to a transfer fabric, while it is at a consistency of solids between about 10 to about 35 percent, and especially between about 20 to about 30 percent. As used herein, a "transfer fabric" is a fabric that is positioned between the molding section and the drying section of the weft fabrication process.
    [42] The transfer to the transfer screen can be done with the aid of positive and / or negative pressure. For example, in one embodiment, a vacuum shoe can apply negative pressure, so that the forming screen and the transfer screen converge simultaneously and diverge at the front edge of the vacuum groove. Typically, the vacuum shoe provides pressure at levels between about 10 to about 25 inches of mercury. As stated above, the vacuum transfer shoe (negative pressure) can be supplemented or replaced by using positive pressure on the opposite side of the web to blow the web onto the next web. In some embodiments, other vacuum shoes can also be used to assist in pulling the fibrous web over the transfer screen surface.
    [43] Generally, the transfer screen moves at a slower speed than the molding screen, to increase the CD and MD stretch of the web, which generally refers to the stretching of a web in its transversal or machine direction (expressed as a percentage of elongation in the sample failure). For example, the difference in relative speed between the two screens can be from about 1 to about 30 percent, in some embodiments from about 5 to about 20 percent, and in some embodiments, from about from 10 to about 15 percent. This is commonly referred to as "fast transfer". During the "fast transfer," many of the weave splices break, and thus force the fabric to bend and fold into depressions on the surface of the transfer screen. Molding to the contours of the transfer screen surface can increase the MD and CD stretch of the weft. Quick transfer from one screen to another can follow the principles taught in any of the following patents, US Patent No. 5,667,636, 5,830,321, 4,440,597, 4,551,199, 4,849,054, all of which are incorporated herein by reference, in a manner consistent with the present description.
    [44] The wet fabric web is transferred from the transfer screen to a direct drying fabric. Typically, the transfer web travels at approximately the same speed as the drying web. However, in certain embodiments, a second quick transfer can be carried out as the web is transferred from the transfer screen to a drying screen. This rapid transfer mentioned here occurs in the second position and is achieved by operating the drying screen at a slower speed than the transfer screen. By carrying out the rapid transfer in two different locations, namely the first and the second position, a fabric product with a CD stretch can be produced.
    [45] In addition to rapid transfer of the fabric web from the transfer screen to the drying screen, the wet fabric web can be macroscopically rearranged to conform to the surface of the drying screen with the aid of a vacuum transfer roller or a vacuum transfer shoe like the vacuum shoe. If desired, the drying web can be operated at a slower speed than the speed of the transfer web to further increase the stretch of the resulting fabric product. The transfer can be carried out with the aid of a vacuum to guarantee the conformation of the wet fabric web with the topography of the drying screen.
    [46] In a particularly preferred embodiment, the web is transferred to the drying screen for final drying, preferably with the aid of a vacuum to ensure the macroscopic reorganization of the web in order to obtain the desired volume and appearance . The use of transfer and drying screens can offer several advantages, as it allows two screens to be specifically designed to meet the fundamental requirements of the products independently. For example, transfer screens are generally optimized to allow efficient conversion from high levels of fast transfer to high stretch MD, while drying screens are designed to provide CD stretch and in large volumes. Therefore, it is useful to have moderately thick and moderately three-dimensional transfer screens and drying screens that are very thick and three-dimensional in the optimized configuration. The result is that a relatively smooth fabric leaves the transfer section and is then macroscopically rearranged (with the aid of a vacuum) to provide the high stretch CD surface topology of the drying screen. The topology of the fabric is completely changed from the transfer screen to the drying screen, and the fibers are macroscopically rearranged, including significant movement between the fibers.
    [47] The drying process can be any non-compressible drying method that tends to preserve the volume or thickness of the single web, including, without limitation, direct drying, infrared radiation, microwave drying, etc. Due to its commercial availability and practicality, direct drying is well known and is one of the commonly used means for non-compressive drying of the web for the purposes of this invention. Suitable drying fabrics include, but are not limited to, fabrics with substantially continuous machine directional grooves, where the grooves are composed of several bundled woven yarns, such as those described in U.S. Patent No. 6,998,024. Other suitable drying fabrics include those disclosed in U.S. Patent No. 7,611,607, which is incorporated here in a manner consistent with the present description, in particular the screens indicated as Fred (t1207-7), Jetson (t1207-6) and Jack (t1207-12). The weft is dried to the final dryness through the drying screen, without being pressed against the surface of a Yankee dryer, and without subsequent curling.
    [48] To further increase the CD weft properties, especially the CD slope, the fabric weft can be rewetted, pressed and dried a second time, as illustrated in FIG. 1. As shown in FIG. 1, the dry fabric web 10 (running in the direction indicated by the arrow 15) is re-moistened (also referred to here as hydrated), using one or more hydration baths 20 on one or both (not shown) sides of the web. Hydration baths can consist of water showers (for example, hydraulic showers, atomized air or ultrasonic showers) steam showers or a combination of water showers and steam showers. This weft rehumidification can be carried out by a liquid water emulsion, liquid mixture, dispersion, water spray, steam or other means known in the art, so that the weft moisture content is increased (measured after the device dehumidification 20 and before pressing device 52, 54) at a level of about 10 to 50 percent, more preferably about 15 to about 40 percent. According to this embodiment, the rehumidifying devices 20 are placed, depending on the type of pressing device and the desired application, very close to nip 58 of the pressing device 54,56. The location of the re-humidification device 20 is adjusted in such a way that the soak time after re-humidification under a desired operating speed of nip 58 is less than about 2 seconds. In this description, soaking time is understood as the time for which rehumidification needs to occur before the nip press effect, and in this respect, the soaking time ends when the contact of the compressed surfaces at the ends of the tightening nip, ie , the compression pressure stops acting during the nip effect.
    [49] In a particularly preferred embodiment, the humidification shower consists of a steam shower 20, which has a compartment 22 that defines a front edge 24 and a rear edge 26. Inside the box compartment 22 is a bank of nozzles independently controlled 31 that are spaced at regular intervals in the transverse direction and distribute steam in the steam chamber 30. The steam supply is made by a steam supply manifold 29 and the steam supply from each nozzle 31 is controlled by a computer (not shown), which receives feedback on the humidity level of the moisture detectors (not shown), for example, range indicators, located downstream of the hydration showers and adjust the steam control valve 32 accordingly. The amount of moisture addition is controlled in order to increase the moisture content of the fabric by about 10 to about 50 percent. The addition of moisture will be done in such a way that a uniform moisture level will be applied after profiling. Profiling and adding moisture can be done by a combination of one or more showers. If the steam showers are used in conjunction with water showers, the preferred configuration would have the steam showers after the water showers.
    [50] In a particularly preferred embodiment, shower 20 is designed with a second camera 34, to subsequently cool the fabric with air. Then, after applying steam to the weft, it can be cooled with cold air through a connector 39 and a nozzle 41, controlled by a valve 42, to a cooling chamber 34. Thus, in a preferred embodiment, the apparatus showering increases the humidity level, corrects non-uniformity and then cools the fabric to temperatures below 180 ° F. Cooling the web serves to promote steam condensation and preserve the gripper during pressing. The steam shower is ideally located very close to the nip of the pressing device, so that the time between the application of steam and pressure is minimized. Minimizing this time will preserve a moisture gradient across the thickness of the weft. According to this preferred embodiment, it may be desirable to add a lubricant to the hydration showers prior to pressing. The sprayed lubricants can be commercially known dispersions / emulsions, such as calcium stearate, polyethylene emulsion, polyglycerides and the like. The lubricating solution can be heated to prevent or reduce the cooling of the heated rollers during normal operation.
    [51] After hydration, the rewetted web 50 is passed through a pressing device, such as a pair of spaced rollers 52, 54 that rotate in the direction indicated by the arrow 56. Although the pressing device shown in FIG. 1 comprises a pair of opposing cylinders 52, 54, it should be considered that different types of press can be used to provide a nip tip through which the rewetted web travels and is subjected to pressing. As illustrated in FIG. 1, the pressing device may comprise a pair of rollers 52 and 54 that form a nip 58 between the two. The rollers can be heated or unheated and can have a clamping pressure of about 1,000 to about 10,000 psi, from about 1,500 to about 5,000 psi and, more preferably, from about 2,000 to about 4,000 psi. In the event that the rollers are heated, the inlet to the rollers should be sufficient to maintain a roll surface temperature of about 75 to about 200 ° F during the pressing of the web.
    [52] The surface of the pressing device can be smooth or patterned. In cases where the surface of the press is shaped, the pattern may comprise a series of grooves arranged on each roll, such that the grooves are oriented perpendicular to each other at the printing point (nip). For example, the upper roll 52 may have grooves spaced apart, extending circumferentially on the roll 52, the grooves having substantially parallel sides and a flat top, measuring about 1 to about 3 mm wide and spaced apart. 1 to about 5 mm. The lower roller 54 may have grooves spaced apart, extending circumferentially in the roller 52, the grooves having substantially parallel sides and a flat top, measuring about 1 to about 3 mm wide and spaced from 1 to about 5 mm. When the circumferentially spaced grooves of the upper roll 52 and the axially spaced grooves of the lower roll 54 are brought closer to nip 58 to press the wetted web 50, the grooves are oriented substantially perpendicular to each other.
    [53] After pressing, the web 60 preferably has a moisture content of about 10 to about 50 percent, more preferably, about 20 to about 40 percent, like about 25 to about 35 percent. The rewetted and pressed web 60 is transported to a drying device for the final drying of the web. The drying device can also comprise a first auxiliary drying device. Such auxiliary dryers may include infrared dryers, microwave dryers, radio frequency dryers, sonic dryers, dielectric dryers, ultraviolet dryers and combinations thereof. Using a microwave dryer, this low humidity regime is ideal, as microwave dryers selectively heat the water inside the cell wall, allowing faster removal of water out of the fiber, without significantly affecting the cellulose. Alternatively, a pair of auxiliary dryers, such as a pair of infrared dryers, are used in series to dry the rewetted and pressed weft (It is understood that three, four, or more primary dryers can be used in series.) The dryer auxiliary dries the rewetted and woven fabric web to a final moisture content of about 5 percent or less, such as from about 0.5 to about 3 percent.
    [54] Once dry, re-moistened and again dried, it is possible to curl the fabric web by transferring it to a dryer before winding, or using alternative methods, such as micro-curling.
    [55] The process of the present description is suitable for the formation of multilayered fabric products. Multilayered fabric products can contain two, three or more layers. In a particular embodiment, a product with two laminated layers is formed according to the present description, where both layers are manufactured using the same papermaking process, such as, for example, direct air drying without curling. However, in other embodiments, the layers can be formed by two different processes. Generally, before being rolled into a cylinder, the first layer and the second layer are bonded to each other. Any suitable method for laminating the wefts together can be used. For example, the process includes a crimping device that causes the layers to be mechanically linked through the interlacing of the fibers. In an alternative embodiment, however, an adhesive can be used to join the layers together. EXAMPLES
    [56] Samples of air-dried and unwrinkled tissue were produced as described in U.S. Patent No. 5,772,845, the description of which is incorporated for reference, in a manner consistent with the present description, in a fabric machine that has a forming screen, transfer screen and drying screen. The single layer fabric was produced with a base weight of 40 gsm using a mixed raw material of 50 percent by weight of softwood long fiber and 50 percent of eucalyptus fibers. The raw material was not refined and no chemicals were added.
    [57] The total level of rapid transfer ranged between 28 and 60 percent, that is, the TAD screen was created to be operated at a speed that was between 28 and 60 percent slower than the forming screen. The forming screen was a Voith 2164 screen, the TAD screen was a screen described as "Jack" in U.S. Patent No. 7,611,607, which is incorporated herein in a manner consistent with the present description, or Voith t-1205-2 (Voith Fabrics, Appleton, WI, illustrated in FIG. 3), and the transfer screens were Voith 2164 or the screen described as "Jetson" in U.S. Patent No. 7,611,607. For each code, the particular fast transfer rate and screen combination are shown in Table 2. TABLE 2


    [58] For each sample, the conditions of the machines and chemical additives were kept constant and no effort was made to compensate for the changes caused by the rapid transfer changes. Likewise, unless specified, other variables, such as vacuum levels, TAD and spool configurations, and pulper conditions remained constant.
    [59] Samples to be moistened, pressed, or both were cut to 3-inch by 6-inch sample sizes. The samples were then subjected to pressing, humidification or pressing and humidification, as established in Table 3 below. The samples were moistened by inserting them into two pre-moistened press plates, illustrated in FIG. 2 (available from Kimtech, Neenah, WI, Model # 195X1-M-1163). The press plates were approximately 10 inches in diameter and had a raised grooved surface, as illustrated in FIG. 2, with a diameter of 9 cm. More specifically, about 10 grams of water was added to an 11.5-inch by 11.5-inch paper towel to moisten the towel. The moistened paper towel was then passed between the raised grooves (shown in detail in FIG. 2B, measuring approximately 2 mm in height and spaced about 1 mm) over the press plates. Approximately 0.3 grams of water was applied to the surface of each press plate. The sample was then placed on a lower pressing plate and the upper pressing plate was lowered onto the sample, so that the moist grooves on both the upper and lower plates touched the sample. The samples remained between the moistened press plates for 30 seconds and then were removed and left to air dry under ambient conditions.
    [60] To press the samples, they were placed between the pressing plates (illustrated in FIG. 2) with the upper plate aligned with the lower plate, so that the grooves in the lower plate were perpendicular to the grooves in the upper plate. The press plates were loaded onto a Carver press (available from Carver Inc., Wabash, IN, Model No. 2518, N / S 2518-366) and subjected to 30,000 pounds of pressure by the Carver press for 30 seconds. The load received by the samples was calculated to be about 3,333 psi.
    [61] Codes that were "moistened and pressed", were first moistened as described above and then pressed as described above. The wet and pressed samples were left to dry under ambient conditions.
    [62] The physical properties are summarized in Table 3, below. Control codes are indicated with a -C and inventive codes are indicated with a -7. Codes submitted to pressing only are indicated with -3 and codes submitted to humidification only are indicated as -5. TABLE 3


    [63] The effect of treatments on the CD properties of the wefts illustrates the inventive effect. First, the pressing step without humidification reduced CD traction and CD stretching; however, the reduction was slight and caused only a slight change in the CD tilt. For example, for code 616, the CD pull decreased from 752 grams by 3 inches to 658 grams by 3 inches for code 616 when the web was pressed.
    [64] Wetting alone (without pressing), on the other hand, increased both CD stretch and CD tensile strength, but only to a small degree, which reflects the slight increase in CD slope. Again, using code 616 as an example, the tensile strength of CD increased from 752 grams by 3 inches to 819 grams by 3 inches, due to wetting alone.
    [65] However, when the weft was subjected to both wetting and pressing, the increase in CD pitch was much greater than the wetting or pressing alone. For example, the CD slope of code 616 increased from 3,795 grams by 3 inches, for control code 616-C to 9,328 grams by 3 inches for the wet and pressed code sample 616-7, an increase of 145 percent, as a result of wetting and pressing.
    [66] This high slope was achieved by maintaining a significant CD stretch in the tissue, approximately 10 percent or more CD stretch. Although part of the increase in the CD slope was attributable to an increase in the CD traction (note the CD slope in the only moistened sample 616-5 having a greater CD traction than the control, it increased to 4,128 grams by 3 inches compared to 3,795 grams by 3 inches for control code 616-C) the increase cannot be explained just by changing the traction.
    [67] One way to remove the influence of the change in tensile strength from the comparison is to divide the CD slope by the CD traction, to obtain a slope / traction ratio. In this case, the ratio of inclination CD to CD traction for samples that have been humidified and pressed is approximately 100 percent greater than that of the other samples. For example, for code 616, the inclination ratios CD to CD traction are about 5 for the control, samples only pressed and only moistened (designated 616-C, 616-3 and 616-5, respectively). But the ratio of CD slope to CD traction of the inventive sample 616-7, which has been moistened and pressed, is much higher - in fact, about 100 percent higher by 10.75. This demonstrates that the increase in the CD slope is not just due to the increase in CD traction. Furthermore, because the CD stretch of code 616-7 is similar to that of the other pressed code 616-3, the effect of the process on the CD stretch is also not the only cause for the greater CD skew.
    [68] Similar results are evident for all other examples, regardless of the type of fabric and level of stretch for the initial UCTAD base fabric. In all cases, the treatment of the invention involving wetting and pressing the fabric yielded a large increase in CD tilt, maintaining a high level of CD stretch.
    [69] The preceding examples are intended to illustrate the particular embodiments of the present description, without limiting the scope of the appended claims.
    权利要求:
    Claims (4)
    [0001]
    1. Method of fabrication of a fabric web, characterized by comprising: (a) forming a web fabric of direct drying with a moisture content of less than 5 percent, (b) rehumidifying the web of direct drying (c) pressing the fabric. rewetted weft, and (d) drying the pressed weft to a moisture content of less than 5 percent.
    [0002]
    2. Method according to claim 1, characterized by the fact that the moisture content of the re-moistened direct drying web is 10 to 50 percent.
    [0003]
    3. Method according to claim 1 or 2, characterized by the fact that the re-moistened direct drying web is subjected to pressing pressures in the range of 1,000 to 5,000 psi (70 to 253 Kg / cm2).
    [0004]
    Method according to any one of claims 1 to 3, characterized in that the rehumidification step comprises vaporizing the direct drying web, optionally further comprising the step of cooling the direct drying web reheated at a temperature below 180 ° C ° F (82 ° C).
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    同族专利:
    公开号 | 公开日
    AU2012356266A1|2014-06-26|
    BR112014015393A8|2017-07-04|
    CN104024524A|2014-09-03|
    US20130160960A1|2013-06-27|
    EP2794992A1|2014-10-29|
    AU2012356266B2|2014-12-11|
    MX2014007370A|2014-08-27|
    MX345810B|2017-02-15|
    KR20140114811A|2014-09-29|
    EP2794992A4|2015-08-26|
    KR101496111B1|2015-02-25|
    BR112014015393A2|2017-06-13|
    EP2794992B1|2017-04-19|
    US8500955B2|2013-08-06|
    WO2013093676A1|2013-06-27|
    CN104024524B|2016-11-23|
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    法律状态:
    2018-03-27| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2019-08-20| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2020-12-22| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-02-02| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 27/11/2012, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    US13/335,118|2011-12-22|
    US13/335,118|US8500955B2|2011-12-22|2011-12-22|Tissue sheets having enhanced cross-direction properties|
    PCT/IB2012/056771|WO2013093676A1|2011-12-22|2012-11-27|Tissue sheets having enhanced cross-direction properties|
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