Method for carbon dioxide fluid oscillation pressure induced fiber three-dimensional network reconstruction

Abstract

A method for carbon dioxide fluid oscillation pressure induced fiber three-dimensional network reconstruction comprises the steps that firstly, a fiber web is conveyed to pass through an entanglement cavity, then a plurality of nozzles arranged at the top of the entanglement cavity eject a plurality of beams of fluid jet flow to the fiber web passing below the nozzles, the fluid jet flow penetrates through or penetrates into the fiber web to entangle the fiber web, and the reinforced fiber web is obtained; the fluid jet flow is composed of supercritical carbon dioxide or subcritical carbon dioxide, the jet mode of the nozzle is oscillation jet flow, and the jet pressure of the multiple beams of fluid jet flow is a periodically oscillating pressure waveform, so that fibers are induced to perform three-dimensional network reconstruction in the thickness direction of the fiber web. According to the design, periodically oscillating pressure waveforms are adopted for entanglement, so that a three-dimensional entanglement structure can be obtained, the firmness is higher, the bulkiness is better, and the water consumption and the energy consumption are lower.

Description

Technical Field

[0001] This invention relates to an entanglement process for nonwoven fabrics, belonging to the field of nonwoven fabrics, and particularly to a method for reconstructing a three-dimensional fiber network induced by carbon dioxide fluid oscillation pressure. Background Technology

[0002] Currently, the commonly used reinforcement method in the field of nonwoven fabrics is hydroentangling, also known as jet web forming, water entanglement, etc. It is a unique and new fiber web consolidation technology in the field of nonwoven fabrics (that is, to entangle the fibers in the fiber web to reinforce the fiber web).

[0003] The entanglement principle of hydroentangling is similar to that of needle punching, but instead of needles, it uses multiple fine water jets generated by high pressure to spray the fiber web. When the water jets pass through the web, they are rebounded by the support curtain and re-entangle. Thus, under the hydraulic action of the high-speed water jets in different directions, the fibers in the web shift, intertwine, and become entangled, thereby strengthening the web. However, hydroentangling has the following drawbacks: When hydroentanglement is used to entangle fibers, a stable high-pressure water flow is used to continuously compact the fiber web, similar to a road roller compacting a road surface. This can indeed compress the fibers together and achieve entanglement. However, this entanglement flattens the fibers in a two-dimensional plane, and the fiber orientation is mainly two-dimensional. The resulting structure is mainly two-dimensional and cannot form a three-dimensional structure. The appearance is a dense but not fluffy structure.

[0004] The information disclosed in this background section is intended only to enhance understanding of the overall background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects and problems of existing technologies where the winding structure is two-dimensional and has poor bulkiness, and to provide a method for reconstructing a three-dimensional fiber network induced by carbon dioxide fluid oscillation pressure with a three-dimensional winding structure and better bulkiness.

[0006] To achieve the above objectives, the technical solution of the present invention is: a method for reconstructing a three-dimensional fiber network induced by carbon dioxide fluid oscillation pressure, wherein the method for inducing the reconstruction of a three-dimensional fiber network includes the following steps: First, a fiber web is made from the raw materials used to make nonwoven fabric. Then, the fiber web is conveyed through the entanglement chamber. Then, multiple jets of fluid are ejected from multiple nozzles at the top of the entanglement chamber onto the fiber web below. The fluid jets penetrate or enter the fiber web to entangle it, resulting in a reinforced fiber web. The fluid jet is composed of supercritical or subcritical carbon dioxide. The nozzle uses an oscillating jet pattern, and the jet pressure of the multiple fluid jets is a periodically oscillating pressure waveform, thereby inducing the fibers to reconstruct a three-dimensional network in the thickness direction of the fiber web.

[0007] For any given fluid jet, once the process of penetrating or entering the fiber web is complete, the fluid jet vaporizes within the entanglement cavity to generate gaseous carbon dioxide.

[0008] The oscillating jet is any one of the following: The first method involves simultaneously increasing or decreasing the injection pressure of all nozzles. The second method involves all nozzles arranged in a predetermined pattern, divided into Group A and Group B in a predetermined order. When the injection pressure of Group A increases simultaneously, the injection pressure of Group B decreases simultaneously, and vice versa.

[0009] In the second type, all nozzles are arranged in a matrix and divided into odd and even groups according to the order of arrangement. When the injection pressure of the odd group increases simultaneously, the injection pressure of the even group decreases simultaneously, and when the injection pressure of the odd group decreases simultaneously, the injection pressure of the even group increases simultaneously.

[0010] The frequency of the oscillating jet is a periodic frequency.

[0011] The gaseous carbon dioxide is first collected from the entanglement chamber, then compressed and cooled to re-fluidize it to obtain supercritical or subcritical carbon dioxide, and then formed into a fluid jet through a nozzle for recycling.

[0012] The nozzle's output end is located inside the entanglement chamber, and the nozzle's input end is connected to the output end of the high-pressure pump via a pulse valve, which is also connected to the central controller via a signal connection.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In the method for reconstructing a three-dimensional fiber network induced by carbon dioxide fluid oscillation pressure of the present invention, during the process of conveying the fiber web made of raw material fibers through the entanglement cavity, multiple nozzles set at the top of the entanglement cavity will oscillate and spray multiple fluid jets (the constituent medium is supercritical carbon dioxide or subcritical carbon dioxide) onto the fiber web passing below. The injection pressure of the multiple fluid jets is a periodically oscillating pressure waveform. The ejected fluid jets will penetrate or enter the fiber web to entangle the raw material fibers in the fiber web until the fiber web is conveyed outside the entanglement cavity, thereby obtaining a reinforced fiber web. The advantages of this design include: Firstly, after the fluid jet is ejected, from the moment it contacts the fiber web until it penetrates or enters the fiber web, the mechanical impact force provided by the fluid jet will violently impact the fibers in the fiber web, causing them to shift and bend, thus resulting in initial entanglement. Secondly, when the jet pressure of the fluid jet weakens, the fibers impacted by the previous fluid jet will relax due to elastic recovery and fluid back-suction effect. In this instant of "relaxation", the fibers gain valuable space and time, no longer pressed firmly on the two-dimensional plane, thus having the opportunity to lift and stretch in the thickness direction (Z direction) (this is a process of guiding the fibers to "self-organize", rather than the direct result of external impact force, and is closer to the process of naturally forming a fluffy structure). They re-displace and bend to cause secondary entanglement. This reconstruction process not only enriches the structure of entanglement, but more importantly, it expands new structural changes in the Z direction (such as bridging structure and arch structure), upgrading the entanglement structure from two-dimensional to three-dimensional, breaking the limitation of the traditional spunlace product fiber orientation being mainly two-dimensional, actively constructing a three-dimensional three-dimensional network structure with significant Z-direction fiber orientation, with stronger strength and better product fluffiness; Thirdly: The overall spray pattern of all nozzles is oscillating spray, and the spray pressure of the multi-jet fluid is a periodically oscillating pressure waveform, thereby inducing the fibers to reconstruct a three-dimensional network in the thickness direction of the fiber web. This makes the mechanical impact force that the fiber web bears during the entire entanglement process present a continuous cycle of "pressing - releasing - pressing again". At the same time, the rebound change in the Z direction also presents a continuous cycle. This cycle repeats itself, realizing the dynamic and flexible "forging" of the fiber web, making it entangled under the periodically oscillating pressure waveform, thereby constructing a stable three-dimensional fluffy structure with extremely high fluffiness, excellent compression resilience and better liquid absorption and moisture wicking performance. Therefore, the present invention uses a periodically oscillating pressure waveform for entanglement, which not only obtains a three-dimensional entanglement structure with stronger strength, but also better fluffiness.

[0014] 2. In the method for reconstructing a three-dimensional fiber network induced by carbon dioxide fluid oscillation pressure of the present invention, the oscillation jetting includes two types. The first type refers to the simultaneous increase or decrease of the jetting pressure of all nozzles. The second type refers to all nozzles arranged in a predetermined pattern, divided into group A and group B according to a predetermined order. When the jetting pressure of group A increases simultaneously, the jetting pressure of group B decreases simultaneously, and vice versa. The advantages of this design include: Firstly, when all nozzles simultaneously increase and decrease in strength, the fabrication of the three-dimensional winding structure becomes more uniform, making it easier to ensure consistent strength and fluffiness of the nonwoven fabric, resulting in a better overall fluffiness. Secondly, when all the nozzles do not increase or decrease synchronously, but are set to increase or decrease dynamically, this will generate various dynamic "pressure traveling waves" on the fiber web, making the fiber movement in the Z direction more diverse, and realizing a richer three-dimensional network reconstruction to meet various different needs. Therefore, the present invention is highly adjustable and can realize a variety of three-dimensional winding structures.

[0015] 3. In the method for reconstructing a three-dimensional fiber network induced by carbon dioxide fluid oscillation pressure of the present invention, for any fluid jet, after the process of penetrating or entering the fiber network is completed, the fluid jet vaporizes in the entanglement cavity to generate gaseous carbon dioxide. This design has the following advantages: This vaporization process is directly generated by the fluid jet as it penetrates or enters the fiber web. It has a relatively high intensity and often occurs on the surface of the fiber web or at the moment of impact. It is beneficial for the local overall oscillation or expansion of the fiber web and can also generate Z-axis impact force, which leads to Z-axis structural reconstruction and enhances the formation of three-dimensional entangled structures. Therefore, the present invention can generate vaporization to enhance the three-dimensional entanglement structure.

[0016] 4. In the method for reconstructing a three-dimensional fiber network induced by carbon dioxide fluid oscillation pressure of the present invention, the constituent medium of the fluid jet is supercritical carbon dioxide or subcritical carbon dioxide. Furthermore, for any given fluid jet, after its penetration or entry into the fiber web, the fluid jet vaporizes within the entanglement cavity to generate gaseous carbon dioxide. This design has the following advantages: Firstly, compared to existing hydroentangling processes, the medium is limited to supercritical or subcritical carbon dioxide, eliminating the use of water entirely and saving significant water resources, thus greatly reducing water consumption. Furthermore, because the jet process is free from water dependence, high-energy-consuming water treatment devices (such as filtration, softening, and purification equipment) can be eliminated from the overall equipment, significantly reducing energy consumption. Additionally, the fluid jet in this design vaporizes within the entanglement chamber after penetrating or entering the fiber web, generating gaseous carbon dioxide. Compared to existing hydroentangling processes, this process eliminates the need for energy-intensive drying equipment, further saving energy. Secondly, the limitation of the fluid jet being composed of supercritical or subcritical carbon dioxide not only ensures that the jet is free of impurities and that the subsequent fluid jet is stable, unlike existing spunlaces which exhibit turbulence, thus facilitating improved entanglement, but also ensures that the vaporization process after spunlaces leaves no residue on the nonwoven fabric, whereas existing spunlaces leave residue. This makes it more suitable for high-end nonwoven products, such as high-end hygiene products. Thirdly, supercritical carbon dioxide is an excellent natural solvent with a strong ability to dissolve oil, grease, and certain additives. Therefore, it can dissolve and remove residual spinning oils (such as those on chemical fibers) and waxes (such as those on natural cellulose fibers like cotton and hemp) in situ while the fibers are entangled during hydroentangling in the fluid jet. This results in a "cleaner" fiber surface, which increases the coefficient of friction and makes it easier for the fibers to form tighter entanglements under mechanical impact, further enhancing the reinforcement effect and increasing the strength of the nonwoven fabric. Fourthly, because the oscillating jet is used and the jet pressure of the multi-jet fluid is a periodically oscillating pressure waveform, it not only avoids the excessive impact of continuous jetting and reduces damage to the fibers, but is especially beneficial to protecting the integrity of brittle or microfibers. Moreover, the energy consumption of this dynamic process is lower than that of the system that maintains constant ultra-high pressure, further reducing energy consumption. Therefore, this invention not only has low water and energy consumption and good entanglement strength, but also leaves no hydroentanglement residue, which is beneficial for producing high-end nonwoven fabrics. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the effect of the fluid jet on the fiber web in this invention.

[0018] Figure 2 This is a top view of the nozzle arrangement in this invention.

[0019] Figure 3 This is a schematic diagram of the three-dimensional entanglement structure in this invention.

[0020] Figure 4 This is a schematic diagram of the interconnected structure between the nozzle, pulse valve, high-pressure pump, and central controller in this invention.

[0021] In the diagram: 1. Fiber web; 2. Entanglement cavity; 3. Fluid jet; 4. Nozzle; 41. Odd number group; 42. Even number group. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] See Figure 1 — Figure 4 A method for reconstructing a three-dimensional fiber network induced by carbon dioxide fluid oscillation pressure, the method comprising the following steps: First, a fiber web is made from the raw materials used to make nonwoven fabric. Then, the fiber web is conveyed through the entanglement chamber. Then, multiple jets of fluid are ejected from multiple nozzles at the top of the entanglement chamber onto the fiber web below. The fluid jets penetrate or enter the fiber web to entangle it, resulting in a reinforced fiber web. The fluid jet is composed of supercritical or subcritical carbon dioxide. The nozzle uses an oscillating jet pattern, and the jet pressure of the multiple fluid jets is a periodically oscillating pressure waveform (such as sine wave, square wave, sawtooth wave, etc.), thereby inducing the fibers to reconstruct a three-dimensional network in the thickness direction of the fiber web.

[0024] For any given fluid jet, once the process of penetrating or entering the fiber web is complete, the fluid jet vaporizes within the entanglement cavity to generate gaseous carbon dioxide.

[0025] The oscillating jet is any one of the following: The first method involves simultaneously increasing or decreasing the injection pressure of all nozzles. The second method involves all nozzles arranged in a predetermined pattern, divided into Group A and Group B in a predetermined order. When the injection pressure of Group A increases simultaneously, the injection pressure of Group B decreases simultaneously, and vice versa.

[0026] In the second type, all nozzles are arranged in a matrix and divided into odd and even groups according to the order of arrangement. When the injection pressure of the odd group increases simultaneously, the injection pressure of the even group decreases simultaneously, and when the injection pressure of the odd group decreases simultaneously, the injection pressure of the even group increases simultaneously.

[0027] The frequency of the oscillating jet is a periodic frequency.

[0028] The gaseous carbon dioxide is first collected from the entanglement chamber, then compressed and cooled to re-fluidize it to obtain supercritical or subcritical carbon dioxide, and then formed into a fluid jet through a nozzle for recycling.

[0029] The nozzle's output end is located inside the entanglement chamber, and the nozzle's input end is connected to the output end of the high-pressure pump via a pulse valve, which is also connected to the central controller via a signal connection.

[0030] The following are supplementary descriptions of the present invention: The fiber web in this invention is made from raw materials used to make nonwoven fabrics, including natural fibers, chemical fibers, and recycled fibers from waste textiles.

[0031] In this invention, the fluid jet is composed of supercritical or subcritical carbon dioxide. The density of such a substance is only 70%-80% of that of water. Although its overall kinetic energy is weaker than that of water when sprayed at the same speed, the fluid jet in this invention still has the ability to penetrate the fiber web because in existing hydroentanglements, not all of the kinetic energy of water is used to penetrate the fiber web.

[0032] Example 1: See Figure 1 — Figure 4 A method for inducing three-dimensional fiber network reconstruction using carbon dioxide fluid oscillation pressure is disclosed. The method includes the following steps: first, a fiber web 1 is made from raw materials used to make nonwoven fabric; then, the fiber web 1 is conveyed through an entanglement cavity 2; then, multiple nozzles 4 located at the top of the entanglement cavity 2 eject multiple fluid jets 3 through the fiber web below it. The fluid jets 3 penetrate or enter the fiber web 1 to entangle the fiber web 1, resulting in a reinforced fiber web; the constituent medium of the fluid jets 3 is supercritical carbon dioxide or subcritical carbon dioxide; the injection mode of the nozzles 4 is oscillating injection, and the injection pressure of the multiple fluid jets is a periodically oscillating pressure waveform, thereby inducing three-dimensional network reconstruction of the fibers in the thickness direction of the fiber web. Preferably, the frequency of the oscillating injection is a periodic frequency.

[0033] Example 2: The basic content is the same as in Example 1, except that: The oscillating jet is any one of the following: The first method involves simultaneously increasing or decreasing the injection pressure of all nozzles 4. The second method involves all nozzles 4 arranged in a predetermined pattern, divided into group A and group B according to a set order. When the injection pressure of group A increases simultaneously, the injection pressure of group B decreases simultaneously, and vice versa. Preferably, all nozzles 4 are arranged in a matrix, divided into odd-numbered groups 41 and even-numbered groups 42 according to the arrangement order. When the injection pressure of odd-numbered groups 41 increases simultaneously, the injection pressure of even-numbered groups 42 decreases simultaneously, and vice versa. Figure 2 As shown: The oscillating jets of the odd-numbered array 41 and the even-numbered array 42 can generate a "pressure traveling wave" that moves forward like a wave on the fiber web 1. This oscillating pressure field can more effectively "rub" the fiber web 1, not only causing the fibers to move up and down, but also prompting the fibers to rearrange and interweave in the plane, thereby achieving a more thorough and uniform three-dimensional network reconstruction.

[0034] Example 3: The basic content is the same as in Example 1, except that: like Figure 4 As shown, the structure between fibers in the reinforced fiber web includes: entanglement structure, bridging structure and arch structure. Among them, the bridging structure and arch structure are particularly unique, which can upgrade the internal structure of the fiber web from two-dimensional to three-dimensional. This breaks the limitation that the fiber orientation of traditional spunlace products is mainly two-dimensional, and actively constructs a three-dimensional mesh structure with a significant Z-direction fiber orientation, which is stronger and the product has better bulkiness.

[0035] Example 4: The basic content is the same as in Example 1, except that: For any fluid jet 1, after it penetrates or enters the fiber web 2, the fluid jet 3 vaporizes within the entanglement cavity 2 to generate gaseous carbon dioxide. This vaporization explosion can further push the already loosened fibers into three-dimensional space, which is beneficial for constructing a three-dimensional entanglement structure.

[0036] Example 5: The basic content is the same as in Example 1, except that: like Figure 4 As shown, the output end of the nozzle 4 is located inside the entanglement cavity, the input end of the nozzle 4 is connected to the output end of the high-pressure pump via a pulse valve, and the pulse valve is connected to the central controller via a signal connection.

[0037] In application, the central controller (such as a PLC) generates a preset electronic signal waveform (such as a sine wave or square wave). This electrical signal drives the pulse valve (a solenoid valve or piezoelectric valve that can switch on and off extremely quickly) to open or close at high speed, so as to "cut" the stable fluid pumped by the high-pressure pump into pulsating jets, thereby realizing the oscillating jet of the nozzle. In addition, by adjusting the frequency and amplitude of the electrical signal, the oscillation frequency and pressure fluctuation range of the output pressure can be precisely controlled to obtain various different oscillation effects, thereby creating a variety of three-dimensional winding structures and achieving a variety of fluffiness.

[0038] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A method of carbon dioxide fluid oscillatory pressure induced fiber three-dimensional network remodeling, characterized by: The method for inducing the three-dimensional network reconstruction of fibers comprises the following steps: First, a web is made from raw fibers for making nonwoven fabrics, and then the web is transported through an entangling chamber, and then a plurality of fluid jets are sprayed from a plurality of nozzles arranged at the top of the entangling chamber to the web passing below, the fluid jets penetrate or enter the web to entangle the web, and a reinforced web is obtained; The fluid jet is composed of supercritical carbon dioxide or subcritical carbon dioxide; The spraying mode of the nozzles is oscillating spraying, and the spraying pressure of the plurality of fluid jets is a periodically oscillating pressure waveform, thereby inducing the three-dimensional network reconstruction of fibers in the thickness direction of the web.

2. The method of carbon dioxide fluid oscillatory pressure induced fiber three- dimensional network reconfiguration of claim 1, wherein: For any fluid jet, when the process of penetrating or entering the web ends, the fluid jet is gasified in the entangling chamber to generate gaseous carbon dioxide.

3. A method of carbon dioxide fluid oscillatory pressure induced fiber three- dimensional network remodeling according to claim 1 or 2, characterized in that: The oscillating spraying is any of the following: The first: the spraying pressure of all nozzles is simultaneously increased or simultaneously decreased; The second: all nozzles are arranged in a set arrangement and divided into group A and group B according to a set order, when the spraying pressure of group A is simultaneously increased, group B is simultaneously decreased, and when the spraying pressure of group A is simultaneously decreased, group B is simultaneously increased.

4. The method of claim 3, wherein the carbon dioxide fluid oscillatory pressure induces remodeling of a three-dimensional network of fibers. In the second, all nozzles are arranged in a matrix and divided into odd-numbered groups and even-numbered groups according to the arrangement order, when the spraying pressure of the odd-numbered groups is simultaneously increased, the even-numbered groups are simultaneously decreased, and when the spraying pressure of the odd-numbered groups is simultaneously decreased, the even-numbered groups are simultaneously increased.

5. The method of claim 1 or 2, wherein the carbon dioxide fluid is a supercritical fluid. The frequency of the oscillating spraying is a periodic frequency.

6. The method of oscillating pressure induced fiber three-dimensional network reconfiguration in carbon dioxide fluid according to claim 1 or 2, characterized in that: The gaseous carbon dioxide is first collected from the entangling chamber, then compressed and cooled to be re-fluidized to obtain supercritical carbon dioxide or subcritical carbon dioxide, and then formed into fluid jets by the nozzles for recycling.

7. The method of claim 1 or 2, wherein the carbon dioxide fluid is a supercritical fluid. The output end of the nozzle is located in the entangling chamber, the input end of the nozzle is connected to the output end of the high-pressure pump through the pulse valve, and the pulse valve is signal-connected to the central controller.

Images