Nonwoven cellulose fiber fabric, method and device for manufacturing the same, method of using the same, and product comprising the same

Abstract

A nonwoven cellulose fiber fabric (102) directly manufactured from a lyocell spinning solution (104), wherein the fabric (102) comprises a network of substantially endless fibers (108) of varying fiber diameters such that the ratio between the largest and smallest fiber diameters is greater than 1.5.

Description

[Technical Field] This invention relates to nonwoven cellulose fiber fabrics, methods for manufacturing nonwoven cellulose fiber fabrics, apparatus for manufacturing nonwoven cellulose fiber fabrics, products or compounds, and methods of use. [Previous Technology] Lyocell technology relates to the direct dissolution of cellulose pulp or other cellulose-based raw materials in polar solvents (such as N-methylmorpholine N-oxide, also referred to as "amine oxide" or "AO") to produce viscous, high-shear-thinning solutions. These solutions can be transformed into a wide range of useful cellulose-based materials. Commercially, this technology is used to produce a range of short cellulose fibers widely used in the textile industry (marketed by Lenzing AG, Lenzing, Austria under the trademark TENCEL®). Other cellulose products derived from Lyocell technology have also been used. Cellulose staple fibers have long been used as a component for transforming into nonwoven webs. However, adapting lyocell technology to directly produce nonwoven webs would yield properties and effects impossible with current cellulose web products. This can be considered a cellulose version of the meltblown and spinning bonding technologies widely used in the synthetic fiber industry, although significant technological differences make it impossible to directly adapt synthetic polymer technology to lyocell. Numerous studies have been conducted to develop techniques for the direct formation of cellulose networks from lyocell solutions (especially WO 98 / 26122, WO 99 / 47733, WO 98 / 07911, US 6,197,230, WO 99 / 64649, WO 05 / 106085, EP 1 358 369, EP 2 013 390). Further techniques are disclosed in WO 07 / 124521 A1 and WO 07 / 124522 A1. [Summary of the Invention] The purpose of this invention is to provide a cellulose-based fabric with appropriately adjustable functional properties. To achieve the above-defined objectives, nonwoven cellulose fiber fabrics, methods for manufacturing nonwoven cellulose fiber fabrics, apparatus for manufacturing nonwoven cellulose fiber fabrics, products, and methods of use are provided according to the independent claims of the patent application. According to an exemplary embodiment of the invention, a nonwoven cellulose fiber fabric (especially one manufactured directly from a lyocell spinning solution, particularly in an in-situ method or in a continuous process that can be performed in a continuous production line) is provided (especially by solution blowing), wherein the fabric comprises a network of substantially endless fibers of varying diameters such that the ratio between the largest and smallest fiber diameters is greater than 1.5. According to another specific example, a method is provided for directly manufacturing (especially solution blown) nonwoven cellulose fiber fabrics from a lyocell spinning solution, wherein the method comprises extruding the lyocell spinning solution through a jet (which may be embodied in or form part of a spinning nozzle or extrusion unit) under the aid of an airflow into a condensing fluid environment (especially a dispersed condensing fluid environment) to thereby form substantially endless fibers; collecting the fibers on a fiber support unit to thereby form the fabric; and adjusting process parameters such that the ratio between the maximum fiber diameter and the minimum fiber diameter is greater than 1.5. According to a further illustrative example, an apparatus for manufacturing (especially solution blown) nonwoven cellulose fiber fabrics directly from a lyocell spinning solution includes a nozzle with spinnerets configured to extrude the lyocell spinning solution by means of an airflow; a coagulation unit configured to provide a coagulating fluid environment to the extruded lyocell spinning solution to form substantially endless fibers; a fiber support unit configured to collect the fibers to form the fabric; and a control unit (such as a processor configured to execute program code for manufacturing the nonwoven cellulose fiber fabric directly from the lyocell spinning solution), configured to adjust process parameters such that the ratio between the maximum fiber diameter and the minimum fiber diameter is greater than 1.5. According to another specific example, nonwoven cellulose fiber fabrics having the above properties are used in at least one of the following groups: wipes, dryer sheets, filters, absorbent hygiene products, medical products, geotextiles, agrotextiles, clothing, building technology products, automotive products, furnishings, industrial products, products related to beauty, leisure, sports or travel, and products related to schools or offices. According to another specific example, a product or compound comprising a fabric having the above-described properties is provided. In this application, the term "nonwoven cellulose fiber fabric" (which may also be specified as nonwoven cellulose filament fabric) specifically refers to a fabric or web composed of a plurality of substantially endless fibers. The term "substantially endless fibers" particularly refers to filament fibers having a significantly longer length than common short fibers. In an alternative blend, the term "substantially endless fibers" particularly refers to a web formed of filament fibers having a significantly smaller number of fiber ends per volume compared to common short fibers. In particular, the number of fiber ends per volume of the endless fibers in the fabric of the exemplary embodiment of the invention may be less than 10,000 ends / cm³, and especially less than 5,000 ends / cm³. For example, when short fibers are used as a substitute for cotton, the length of these short fibers may be 38 mm (corresponding to the typical natural length of cotton fibers). In contrast, the length of the substantially endless fibers in the nonwoven cellulose fiber fabric may be at least 200 mm, and especially at least 1000 mm. However, those skilled in the art will recognize that even endless fibers can be interrupted, which can be achieved during and / or after fiber formation through various processes. Therefore, nonwoven cellulose fiber fabrics made from substantially endless cellulose fibers have a significantly lower fiber count per mass compared to nonwoven fabrics made from short fibers of the same denier. Nonwoven cellulose fiber fabrics can be manufactured by spinning multiple fibers and by thinning and stretching these fibers toward a more mobile fiber support unit. This forms a three-dimensional network or mesh of cellulose fibers, constituting the nonwoven cellulose fiber fabric. This fabric can be made from cellulose as a major or sole component. In this application, the term "lyocell spinning solution" may specifically refer to a solvent (e.g., a polar solution of substances such as N-methyl-morphofolin, NMMO, "amine oxide," or "AO") in which cellulose (e.g., wood pulp or other cellulose-based raw materials) is dissolved. This lyocell spinning solution is a solution, not a melt. Cellulose filaments can be produced from this lyocell spinning solution by reducing the concentration of the solvent (e.g., by contacting the filament with water). The process of initially producing cellulose fibers from a lyocell spinning solution can be described as coagulation. In this application, the term "airflow" may specifically refer to the flow of gas (such as air) substantially parallel to the direction of movement of the cellulose fiber or its preform (i.e., the lyocell spinning solution) at the time the lyocell spinning solution leaves or has left the spinning nozzle. In this application, the term "condensate fluid" may specifically refer to a non-solvent fluid (i.e., a gas and / or liquid that may include solid particles) capable of diluting the lyocell spinning solution and exchanging with the solvent to the extent that the cellulose fiber is formed from the lyocell filament. For example, such a condensate fluid may be a water mist. In this application, the term "process parameters" may specifically refer to all physical and / or chemical and / or device parameters of the substances and / or apparatus components used in the manufacture of nonwoven cellulose fiber fabrics that can affect the properties of the fibers and / or the fabric (especially the fiber diameter and / or fiber diameter distribution). These process parameters may be properties of the fibers in the nonwoven cellulose fiber fabric that can be automatically adjusted by a control unit and / or manually adjusted by a user. Physical parameters that can affect the properties of the fibers (especially their diameter or diameter distribution) may be the temperature, pressure, and / or density of the different media involved in the process (such as the lyocell spinning solution, the condensing fluid, the airflow, etc.). Chemical parameters may be the concentration, content, and pH value of the involved media (such as the lyocell spinning solution, the condensing fluid, etc.). The device parameters may include the size of the spinneret orifice and / or the distance between the spinneret orifices, the distance between the spinneret orifice and the fiber support unit, the conveying speed of the fiber support unit, the provision of one or more arbitrary in-situ post-processing units, the airflow, etc. The term "fiber" can specifically refer to an elongated portion of a material containing cellulose, for example, whose cross-section is approximately circular or irregular, randomly twisted with other fibers. The aspect ratio of a fiber can be greater than 10, particularly greater than 100, and even more particularly greater than 1000. This aspect ratio is the ratio between the length of the fiber and its diameter. Fibers can be interconnected to form a network by merging (to form an integrated multi-fiber structure) or by friction (so that when the relatively moving fibers are in physical contact with each other, they remain separate but are weakly mechanically coupled by the applied frictional force). Fibers can be substantially cylindrical; however, they can be straight, curved, twisted, or wavy. Fibers can be composed of a single homogeneous material (i.e., cellulose). However, such fibers may also contain one or more additives. Liquid materials such as water or oil can accumulate between the fibers. In this document, the term “jet nozzle with spinnerets” (which may be referred to, for example, as “spinneret arrangement”) can be any structure that includes a linearly arranged spinneret arrangement. In this application, the phrase "the ratio between the maximum fiber diameter and the minimum fiber diameter is greater than 1.5" or its equivalent "regarding a difference of more than 50% between the fiber diameter and the minimum diameter" may specifically indicate that the ratio between the maximum fiber diameter and the minimum fiber diameter is multiplied by 100%, and 100% is subtracted from the result to obtain a value of 50% or more. In other words, the ratio between the maximum fiber diameter and the minimum fiber diameter can be higher than 1.5. According to one specific example, a nonwoven cellulose fiber fabric is provided, which can be manufactured into a network of substantially endless cellulose fibers exhibiting a significant non-uniformity of more than 50% in terms of fiber diameter. It has been demonstrated that the diameter distribution of these fibers in the nonwoven cellulose fiber fabric is a powerful design parameter for adjusting the physical properties (especially mechanical properties) of the resulting fabric. With a suitable variation of at least 50% between the maximum and minimum diameters of the fabric, a mechanically highly robust or stiff fabric can be obtained. Without wishing to be confined to a particular theory, it is now believed that this non-uniform distribution of fiber thickness leads to the self-organization of the fiber network, inhibiting relative movement between individual fibers. Conversely, these fibers tend to clamp together, thereby obtaining a compound with high stiffness. Descriptively speaking, introducing certain non-uniformities in the fiber manufacturing process can be generally translated into non-uniformity in the thickness or diameter distribution of these fibers in the fabric. However, it should be mentioned that by changing the fiber diameter, which is a fabric design parameter, fiber properties can be adjusted in a more general way, thus altering the physical properties of the fabric in a wide range (where reinforcing stiffness is just one option or example). For instance, changing the fiber diameter can also be a powerful measure for adjusting the moisture management of the manufactured fabric. [Simplified Explanation of the Diagram] The present invention will be described in detail below with reference to specific examples, but the present invention is not limited to these specific examples. Figure 1 illustrates an apparatus for manufacturing nonwoven cellulose fiber fabrics, which are formed directly from a lyocell spinning solution condensed by a condensing fluid according to an exemplary embodiment of the invention. Figures 2 to 4 show experimentally captured images of nonwoven cellulose fiber fabrics according to exemplary embodiments of the present invention, wherein the merging of individual fibers has been completed by a specially customized process. Figures 5 and 6 show experimentally captured images of nonwoven cellulose fiber fabrics according to exemplary embodiments of the present invention, wherein fiber expansion has been completed, wherein Figure 5 shows the fiber fabric in a dry, unexpanded state and Figure 6 shows the fiber fabric in a moist, expanded state. Figure 7 shows an experimentally captured image of a nonwoven cellulose fiber fabric according to an exemplary embodiment of the present invention, wherein the formation of two overlapping fiber layers has been accomplished by a specific process performing two rows of nozzles. Figure 8 shows a schematic image of a fiber of a nonwoven cellulose fiber fabric according to an exemplary embodiment of the present invention, wherein the fiber shown has multiple segments with different fiber thicknesses. Figure 9 shows a schematic image of interconnected fibers of a nonwoven cellulose fiber fabric according to another exemplary embodiment of the present invention, wherein the different fibers shown have different fiber thicknesses. Figure 10 shows a schematic image of the fibers of a nonwoven cellulose fiber fabric according to another exemplary embodiment of the present invention, wherein the different fibers of the shown fiber have different fiber thicknesses and two fibers of the shown fiber are integrated and interconnected along a merging line to form a superstructure fiber structure. Figure 11 shows a schematic image of a nonwoven cellulose fiber fabric composed of two stacked and merged interconnected fiber layers with different fiber thicknesses, according to another exemplary embodiment of the present invention. Figure 12 illustrates part of an apparatus for manufacturing a nonwoven cellulose fiber fabric consisting of two stacked layers of endless cellulose fiber webs according to an exemplary embodiment of the present invention. Figures 13 and 14 show experimentally captured images of nonwoven cellulose fiber fabrics according to exemplary embodiments of the present invention, wherein different fibers in different fiber segments have substantially different diameters. Figure 15 shows a schematic image of a nonwoven cellulose fiber fabric composed of three stacked layers with different fiber diameters, according to an exemplary embodiment of the present invention.

Implementation Method

Claims

1. A nonwoven cellulose fiber fabric (102) directly manufactured from a lyocell spinning solution (104), wherein the fabric (102) comprises a network of substantially endless fibers (108) of varying fiber diameters such that the ratio between the largest and smallest fiber diameters is greater than 1.5, wherein the different fiber systems of the fibers (108) are at least partially located in different distinguishable layers (200, 202), wherein at least 80% by mass of the fibers (108) have an average fiber diameter ranging from 3 μm to 40 μm, and wherein at least some of the fibers (108) are aligned side-by-side with each other at least along a portion of their length to form a superordinate fiber structure (206) having a diameter larger than that of the individual fibers (108) of the superordinate fiber structure (206).

2. The fabric (102) of claim 1 includes at least one of the following features: the fiber diameters of different segments of the same fiber (108) are different, such that the ratio between the maximum fiber diameter and the minimum fiber diameter of the fiber (108) is greater than 1.5; the fiber diameters of different fibers (108) are different, such that the ratio between the maximum fiber diameter of one of the fibers (108) and the minimum fiber diameter of the other of the fibers (108) is greater than 1.

5.

3. The fabric (102) of claim 1 or 2 includes at least one of the following features: the fibers (108) of different layers (200, 202) are integrally connected at at least one merging position (204) between the layers (200, 202); the fibers (108) at least partially located in different layers (200, 202) have different fiber diameters; the fibers (108) of different layers (200, 202) have the same fiber diameter; the fibers (108) of different layers (200, 202) provide different functions, wherein the different functions include at least one of the group consisting of different wicking properties, anisotropic behavior, different liquid absorption capacity, different cleanability, different roughness, different smoothness, and different stability.

4. The fabric (102) of claim 1 or 2, wherein at least 80% by mass of the fibers (108) have an average fiber diameter ranging from 3 μm to 15 μm.

5. The fabric (102) of claim 1 or 2, wherein the fibers (108) have a copper content of less than 5 ppm and / or a nickel content of less than 2 ppm.

6. The fabric (102) of the first or second claim of the patent application, wherein the oil absorption capacity of the fabric (102) is at least 500 by mass.

7. The fabric (102) of claim 1 or 2, wherein the fabric (102) comprises fibers (108) of different diameters such that the ratio between the largest fiber diameter and the smallest fiber diameter is greater than 2.

5.

8. A method for directly manufacturing a nonwoven cellulose fiber fabric (102) from a lyocell spinning solution (104), wherein the method comprises extruding the lyocell spinning solution (104) through a plurality of nozzles (122) having spinnerets (126) under the aid of an airflow (146) into a cohesive fluid (106) environment to thereby form substantially endless fibers (108); collecting the fibers (108) on a movable fiber support unit (132) to thereby form the fabric (102); adjusting process parameters to make the fiber diameters of the fibers (108) different, such that the ratio between the largest fiber diameter and the smallest fiber diameter is... Greater than 1.5, the different fiber systems of the fibers (108) are at least partially located in different distinguishable layers (200, 202), at least some of the fibers (108) are aligned side by side with each other at least along a portion of their length to form a super-fiber structure (206), wherein the super-fiber structure (206) has a diameter larger than that of the individual fibers (108) forming the super-fiber structure (206); wherein adjusting the process parameters for adjusting the fiber diameter further includes: sequentially arranging the plurality of nozzles (122) with spinnerets (126) of different properties along the movable fiber support unit (132).

9. The method of claim 8, comprising at least one of the following features: wherein adjusting the process parameters for adjusting the fiber diameter comprises adjusting the coagulation conditions of the fibers (108); wherein the plurality of nozzles (122) having spinnerets (126) have different properties in at least one aspect of a group consisting of different spinneret (126) diameters, different airflow (146) velocities, different airflow (146) volumes and different airflow (146) pressures.

10. The method of claim 8 or 9, wherein the method further comprises, after being collected on the fiber support unit (132), further processing the fibers (108) and / or the fabric (102) in situ by means of at least one of the group consisting of hydro-entanglement, needle punching, impregnation, steam treatment using pressurized steam, gas treatment using pressurized gas, and calendering.

11. An apparatus (100) for directly manufacturing a nonwoven cellulose fiber fabric (102) from a lyocell spinning solution (104), wherein the apparatus (100) comprises: a plurality of nozzles (122) having spinnerets (126) configured for extruding the lyocell spinning solution (104) by means of an airflow (146); a coagulation unit (128) configured to provide a coagulating fluid (106) environment to the extruded lyocell spinning solution (104) to thereby form substantially endless fibers (108); a movable fiber support unit (132) configured to collect the fibers (108) to thereby form the fabric (102); and a control unit (140) configured to... The process parameters are adjusted to make the fibers (108) different in terms of fiber diameter, such that the ratio between the maximum fiber diameter and the minimum fiber diameter is greater than 1.

5. The different fibers of the fibers (108) are located at least partially in different distinguishable layers (200, 202). At least some of the fibers (108) are aligned side by side with each other at least along a portion of their length to form a superfiber structure (206), wherein the superfiber structure (206) has a larger diameter than the individual fibers (108) forming the superfiber structure (206). The plurality of nozzles (122) with spinnerets (126) are arranged sequentially along the movable fiber support unit (132) according to different properties.

12. A method of using a nonwoven cellulose fiber fabric (102) as claimed in any one of claims 1 to 7, for use in at least one of the following: wipes, dryer sheets, filters, hygiene products, medical products, geotextiles, agrotextiles, clothing, building technology products, automotive products, furnishings, industrial products, products related to beauty, leisure, sports or travel, and products related to schools or offices.

13. A product comprising a fabric (102) as described in any one of claims 1 to 7 of the patent application.

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