Production process and equipment for viscose-based staple fiber felt with gradient density distribution

Abstract

The present invention provides a production process and equipment for viscose-based staple fiber felt with a gradient density distribution, relating to the technical field of viscose-based fiber material processing. The process includes: using three types of viscose staple fibers with different physical parameters as gradient raw materials, using a mixer assembly to pre-distribute the three gradient raw materials, using a four-curtain laying machine for three-layer stacking, using a five-zone gradient needling machine to independently control the needling parameters of each zone, using a three-stage hot air tunnel for layered heating treatment, then performing differentiated surface treatment, and then using a CNC cutting machine for precise slitting. Through key technologies such as three-level fiber raw material design, layered laying, five-zone gradient needling, and hot-pressing gradient strengthening, a precise and controllable gradient density distribution of the felt material from the surface layer to the core layer is achieved, solving the problem of uneven fiber density transition or poor process repeatability caused by the lack of a systematic gradient construction method.

Description

Technical Field

[0001] The invention relates to the technical field of viscose-based fiber material processing, in particular to a production process and equipment for viscose-based staple fiber felt with gradient density distribution. Background Art

[0002] Viscose-based staple fiber felt is widely used in many fields due to its good hygroscopicity, flexibility and environmental friendliness. The felt prepared by traditional production processes usually has a uniform density structure. Therefore, viscose-based staple fiber felt with a gradient density distribution is needed to meet the demand for gradient changes in material properties in high-end applications.

[0003] In the existing technology, it is difficult to achieve density gradient control during the production of viscose-based staple fiber felt with gradient density distribution through a single fiber raw material and a uniform needling process. Some studies have attempted to change the fiber mixing ratio or needling parameters, but lack a systematic gradient construction method, resulting in uneven fiber density transition or poor process repeatability. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a production process and equipment for viscose-based staple fiber felt with gradient density distribution to solve the problems mentioned in the above background technology.

[0005] To solve the above technical problems, the present invention is achieved through the following technical solutions: The present invention provides a production process and equipment for viscose-based staple fiber felt with gradient density distribution, comprising the following steps:

[0006] First, three raw material storage tanks store three types of viscose staple fibers with different physical parameters as gradient raw materials. The three types of viscose staple fibers with different physical parameters are divided into an upper loose layer fiber, a middle transition layer fiber, and a lower dense layer fiber;

[0007] Second, three mixer components are used to achieve pre-distribution of three types of gradient raw materials. 30%-40% of the upper loose layer fibers are mixed with 5%-10% of the low-melting-point adhesive fibers, 30%-40% of the middle loose layer fibers are mixed with 10%-15% of the functional fillers, and 30%-40% of the lower dense layer fibers are processed separately. The opening degree of fibers of different levels is then controlled by an opener. The speed of the opening roller of the upper loose layer fibers is 800-1000 r / min, and the opening time is 30-40s to maintain a high fluffiness of the upper loose layer fibers. The speed of the opening roller of the lower dense layer fibers is 500-700 r / min, and the opening time is 50-60s.

[0008] Third, a four-curtain laying machine is used to lay three layers of superimposed nets, and a 5-10kV electrostatic field is applied between the upper loose layer fibers, the middle transition layer fibers, and the lower dense layer fibers. The charge difference of the modified fibers is used to enhance the interlayer bonding force and reduce stratification.

[0009] Fourth, a five-zone gradient needling machine is used. Each zone’s needling parameters are independently controlled. The thickness of the felt is monitored online in real time, and the pressure of the five-zone gradient needling machine is adjusted in a coordinated manner to ensure that the density gradient deviation is ≤5%;

[0010] Fifth, a three-stage hot air tunnel is used to perform heating treatment in layers;

[0011] Sixth, use a CNC cutting machine to perform precise cutting according to the density gradient curve of the target product to ensure that the density distribution in the thickness direction meets the design requirements.

[0012] Furthermore, the three raw material storage tanks in step one are arranged horizontally from left to right. The upper loose layer fibers stored in the first raw material storage tank have a linear density of 1.0-1.5dtex, a length of 25-35mm, and a breaking strength ≥2.5cN / dtex. The middle transition layer fibers stored in the second raw material storage tank have a linear density of 1.5-2.5dtex, a length of 35-50mm, and a breaking strength ≥3.0cN / dtex. The lower dense layer fibers stored in the third raw material storage tank have a linear density of 2.5-3.5dtex, a length of 50-65mm, and a breaking strength ≥3.5cN / dtex. A surface modification treatment component is installed below the third raw material storage tank. The surface modification treatment component performs cationic modification treatment on the lower dense layer fibers by dipping them in a polydimethyldiallylammonium chloride solution with a mass fraction of 0.5%-1.0%, thereby increasing the surface charge density of the fibers and enhancing the fiber entanglement force during needle punching.

[0013] Furthermore, the four-curtain laying machine in step three lays the upper loose layer fibers, the middle transition layer fibers and the lower dense layer fibers respectively, the lower dense layer fibers are laid at the bottom, the laying speed of the lower dense layer fibers is 5-10m / min, the surface density is 40-60g / m², and the fiber orientation is ≥60°, and then the middle transition layer fibers are laid, the laying speed of the middle transition layer fibers is 10-15m / min, and the surface density is 30-50g / m 2 , fiber orientation is 40°-50°, the upper loose layer of fibers is laid on the top, the laying speed of the upper loose layer of fibers is 15-20m / min, the fiber web surface density is 20-30g / m², the fiber orientation is ≤30°, and the four-curtain laying machine adopts layered laying combined with electrostatic adsorption technology to achieve a gradient distribution of fiber orientation of 20°-70° and surface density of 20-60g / m².

[0014] Furthermore, the five-zone gradient needling machine in step 4 includes a five-zone independent control system, and the needling density ranges from 80 to 350 needles / cm 2 , the depth changes gradually from 5 to 22 mm.

[0015] Furthermore, the three-stage hot air tunnel in step five processes the upper loose layer fibers, the middle transition layer fibers and the lower dense layer fibers respectively. The upper loose layer fibers are heated to 100-120°C to activate the local bonding of the low-melting point fibers on the surface. The middle transition layer fibers are kept warm at a temperature of 120-140°C to promote the combination of functional fillers and fibers. The lower dense layer fibers are cured and heated to 140-160°C to achieve deep entanglement of the dense layer fibers. A gradient pressure of 0.1-0.5MPa is applied during the shaping process, and the upper layer pressure ≤ middle layer pressure ≤ lower layer pressure to further strengthen the density gradient structure.

[0016] Furthermore, the bottoms of the three raw material storage boxes are installed on the top of the support bracket one; the support bracket two is installed on the bottom of one side of the support bracket one; the bottoms of the three raw material storage boxes are all installed with discharge pipes; the discharge pipes are installed with control valves, and the discharge pipe at the bottom of the third raw material storage box is installed with a surface modification treatment component; and the side of the raw material storage box is installed with a storage box.

[0017] Furthermore, different processing materials are stored inside the storage box, and a guide tube is installed at the bottom of the storage box, wherein a control valve is installed on the guide tube; three mixer assemblies are installed on the inner top of the support bracket one; the tops of the three mixer assemblies are respectively connected to the discharge pipe and the bottom of the guide tube, and connecting support plates are rotatably installed at the upper and lower ends of the mixer assembly.

[0018] Furthermore, a power plate is installed on the side end of the connecting support plate; a groove is provided on the side of the power plate, and the power plate is slidably installed inside the mixer assembly; an air pump is installed on the outside of the mixer assembly, and a main pipe is installed on the output end of the air pump; a collecting pipe is installed on the side end of the main pipe; the side end of the collecting pipe is connected to a diversion pipe; and evenly distributed air intake pipes are installed on the diversion pipe.

[0019] Furthermore, the side end of the air inlet pipe is installed on the inner side of the mixer assembly; a return pipe is also installed on the top of the mixer assembly; the lower end of the return pipe is connected to the input end of the bottom of the air pump outside the mixer assembly; a driving cylinder is installed at the bottom of the mixer assembly, and a traction plate is installed on the output end of the bottom of the driving cylinder; a telescopic sealing cover is installed at the bottom of the mixer assembly; a telescopic tube is installed in the middle position of the bottom of the telescopic sealing cover; the telescopic tube runs through the traction plate.

[0020] Furthermore, three openers are installed on the inner side of the support bracket one; a four-curtain web laying machine, a sliding guide rail, a three-stage hot air tunnel and a surface treatment component are installed on the top of the support bracket two in sequence from back to front; the input end of the opener is connected to the bottom of the telescopic tube, and the output end of the opener is connected to the input end of the four-curtain web laying machine; an electrostatic component is installed on the four-curtain web laying machine, and the output end of the four-curtain web laying machine is connected to the side end of the sliding guide rail; a laser thickness gauge is installed on one side of the five-zone gradient needling machine; the five-zone gradient needling machine, the three-stage hot air tunnel and the surface treatment component are distributed on the sliding guide rail from back to front; a spray pipe is installed inside the surface treatment component; and a CNC cutting machine is also installed on the front end of the sliding guide rail.

[0021] The present invention provides a production process and equipment for viscose-based staple fiber felt with gradient density distribution, which has the following beneficial effects:

[0022] The present invention realizes the precise and controllable gradient of the density distribution of the solid felt material from the surface layer to the core layer through three-level fiber raw material design, layered laying, five-zone gradient needling and hot pressing gradient strengthening, so that the solid felt has excellent functional zoning, enabling it to exhibit specific performance advantages in each area according to the needs of different application scenarios. In the field of high-end filtration, the solid felt material can achieve more efficient and precise filtration effects by virtue of its gradient density structure.

[0023] In addition, an air pump is used to generate air flow, which is introduced into the grooves on the side of the power plate through the reasonable layout of the main pipe, collecting pipe, branch pipe and intake pipe, driving the power plate and the connecting support plate to rotate and mix the fibers. This not only improves the uniformity of the mixing, but also realizes the recycling of the air flow through the return pipe with a filtering structure, reducing energy consumption, improving production efficiency, and also reducing environmental pollution during the production process.

[0024] During the mixing process, by reducing the stirring force, the fiber breakage damage is effectively reduced, ensuring the integrity and performance of the fiber. This is crucial for improving the quality and performance of the final felt material, especially for some applications that have high requirements for fiber strength and length. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments are briefly introduced below.

[0026] The drawings described below only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0027] In the attached figure:

[0028] Figure 1 Shown is a block diagram of the production process of the present invention;

[0029] Figure 2 Shows a schematic diagram of the overall structure of the application equipment in the present invention;

[0030] Figure 3 It shows a schematic diagram of the three-dimensional structure of the raw material storage box of the present invention;

[0031] Figure 4 A schematic diagram of the three-dimensional structure of the mixer assembly of the present invention is shown;

[0032] Figure 5 A schematic diagram of the three-dimensional structure of the telescopic sealing cover of the present invention is shown;

[0033] Figure 6 A schematic cross-sectional view of a mixer assembly according to the present invention is shown;

[0034] Figure 7 A schematic diagram of the three-dimensional structure of the air intake pipe of the present invention is shown;

[0035] Figure 8 A schematic diagram of the three-dimensional structure of the four-curtain web laying machine of the present invention is shown;

[0036] Figure 9 A schematic diagram of the three-section hot air tunnel structure of the present invention is shown.

[0037] Reference Signs List

[0038] 1. Support bracket 1; 101. Support bracket 2; 102. Raw material storage box; 103. Discharge pipe; 104. Surface modification treatment component; 105. Storage box; 106. Diversion pipe;

[0039] 2. Mixer assembly; 201. Connecting support plate; 202. Power plate; 203. Main flow pipe; 204. Collecting pipe; 205. Diverter pipe; 206. Inlet pipe; 207. Return pipe; 208. Traction plate; 209. Telescopic pipe; 2010. Telescopic sealing cover;

[0040] 3. Opening machine; 301. Four-curtain web laying machine; 302. Electrostatic component; 303. Sliding guide rail; 304. Five-zone gradient needling machine; 305. Laser thickness gauge; 306. Three-section hot air tunnel; 307. Surface treatment component; 308. Spray pipe; 309. CNC cutting machine. DETAILED DESCRIPTION

[0041] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Please refer to Figures 1 to 9 :

[0043] Example 1: The present invention proposes a production process and equipment for viscose-based staple fiber felt with gradient density distribution, comprising the following steps:

[0044] 1. Gradient fiber raw material selection: Three raw material storage tanks 102 store three types of viscose staple fibers with different physical parameters as gradient raw materials. The three types of viscose staple fibers with different physical parameters are divided into an upper loose layer fiber, a middle transition layer fiber, and a lower dense layer fiber;

[0045] Second, multi-level fiber pre-distribution: three mixer components 2 are used to achieve three types of gradient raw material pre-distribution respectively. 30%-40% of the upper loose layer fiber is mixed with 5%-10% of the low-melting point adhesive fiber, 30%-40% of the middle loose layer fiber is mixed with 10%-15% of the functional filler, and 30%-40% of the lower dense layer fiber is processed separately. The opening degree of different layers of fibers is then controlled by the opener 3. The speed of the upper fiber opening roller is 800-1000r / min, and the opening time is 30-40s to maintain a high fluffiness of the upper fiber. The speed of the lower fiber opening roller is 500-700r / min, and the opening time is 50-60s to avoid excessive damage to the strength of the lower fiber.

[0046] 3. 3D Gradient Lapping: A four-curtain lapping machine 301 is used to lay three layers of mesh. A 5-10kV electrostatic field is applied between the upper loose layer fibers, the middle transition layer fibers, and the lower dense layer fibers. The charge difference of the modified fibers is used to enhance the interlayer bonding force and reduce stratification.

[0047] Fourth, gradient needling densification treatment, multi-level needling system: adopt five-zone gradient needling machine 304 to independently control the needling parameters of each zone, through online real-time monitoring of the felt thickness, linkage adjustment of the pressure of the five-zone gradient needling machine 304, to ensure that the density gradient deviation is ≤5%; the needling density of the upper loose layer fiber is 80-120 needles / cm², the needling depth is 18-22mm, the needling model adopts three-corrugated needle φ0.8mm, the frequency is 600-800 times / min, the middle transition layer fiber is divided into transition zone 1 and transition zone 2, the needling density of transition zone 1 is 120-180 needles / cm², the needling depth is 15-18mm, the needling model adopts four-corrugated needle φ0.6mm, the frequency is 80 0-1000 times / min, the needling density of the transition zone II is 180-240 needles / cm², the needling depth is 12-15mm, the needling model uses a five-corner needle φ0.5mm, and the frequency is 1000-1200 times / min. The lower dense layer fiber is divided into dense zone I and dense zone II. The needling density of dense zone I is 240-300 needles / cm², the needling depth is 8-12mm, the needling model uses a six-corner needle φ0.4mm, and the frequency is 1200-1400 times / min. The needling density of dense zone II is 300-350 needles / cm², the needling depth is 5-8mm, the needling model uses a barbed needle, and the frequency is 1400-1600 times / min;

[0048] 5. Thermal bonding gradient strengthening treatment, gradient heating and shaping: using a three-stage hot air tunnel 306, heating treatment is carried out in layers;

[0049] 6. Post-processing and performance control, differentiated surface treatment: The upper surface is treated with a softener to improve skin-friendliness and breathability, while the lower surface is treated with a water-repellent spray to enhance resistance to liquid penetration. The product is then precisely cut using a CNC cutting machine 309 according to the density gradient curve of the target product to ensure that the density distribution in the thickness direction meets the design requirements.

[0050] The three raw material storage boxes 102 in step 1 are arranged horizontally from left to right. The first raw material storage box 102 stores the upper loose layer fiber with a linear density of 1.0-1.5 dtex, a length of 25-35 mm, and a breaking strength of ≥2.5 cN / dtex. The second raw material storage box 102 stores the middle transition layer fiber with a linear density of 1.5-2.5 dtex, a length of 35-50 mm, and a breaking strength of ≥3.0 cN / dtex. The third raw material storage box 102 stores the lower dense layer fiber with a linear density of 2.5-3.5 dtex, a length of 50-65 mm, and a breaking strength of ≥3.5 cN / dtex. A surface modification component 104 is installed below the storage box 102; the surface modification component 104 performs cationic modification on the lower dense layer fibers by dipping in a polydimethyldiallyl ammonium chloride solution having a mass fraction of 0.5%-1.0%, thereby increasing the surface charge density of the fibers and enhancing the fiber entanglement force during needle punching; the four-curtain laying machine 301 in step three lays the upper loose layer fibers, the middle transition layer fibers, and the lower dense layer fibers respectively, and the lower dense layer fibers are laid at the bottom, with a laying speed of 5-10 m / min, a surface density of 40-60 g / m², and a fiber orientation of ≥60°, and then lays the middle transition layer fibers. The laying speed of the transition layer fiber and the middle transition layer fiber is 10-15m / min, the surface density is 30-50g / m², and the fiber orientation is 40°-50°. The upper loose layer fiber is laid on the top, and the laying speed of the upper loose layer fiber is 15-20m / min, the fiber web surface density is 20-30g / m², and the fiber orientation is ≤30°. The four-curtain laying machine 301 adopts layered laying combined with electrostatic adsorption technology to achieve a gradient distribution of fiber orientation of 20°-70° and surface density of 20-60g / m²; the five-zone gradient needle loom 304 in step 4 includes a five-zone independent control system, and the needle density ranges from 80-350 needles / c m², with a gradient change of 5-22mm in depth; the three-stage hot air tunnel 306 in step five processes the upper loose layer fibers, the middle transition layer fibers, and the lower dense layer fibers respectively. The upper loose layer fibers are heated to 100-120°C to activate the local bonding of the low-melting-point fibers on the surface. The middle transition layer fibers are kept warm at a temperature of 120-140°C to promote the bonding of functional fillers with the fibers. The lower dense layer fibers are cured and heated to 140-160°C to achieve deep entanglement of the dense layer fibers. A gradient pressure of 0.1-0.5MPa is applied during the shaping process, with the upper layer pressure ≤ middle layer pressure ≤ lower layer pressure, to further strengthen the density gradient structure.

[0051] The bottoms of the three raw material storage tanks 102 are mounted on the top of the support bracket 1; a support bracket 2 101 is mounted on the bottom of one side of the support bracket 1; a discharge pipe 103 is mounted on the bottom of each of the three raw material storage tanks 102; a control valve is mounted on the discharge pipe 103, and a surface modification treatment component 104 is mounted on the discharge pipe 103 at the bottom of the third raw material storage tank 102; a storage box 105 is mounted on the side of the raw material storage tank 102; different processing materials are stored in the storage box 105, and a guide pipe 106 is mounted on the bottom of the storage box 105, wherein a control valve is mounted on the guide pipe 106;

[0052] Three mixer assemblies 2 are installed on the inner top of the support bracket 1; the tops of the three mixer assemblies 2 are respectively connected to the bottom of the discharge pipe 103 and the guide pipe 106, and the upper and lower ends of the mixer assembly 2 are rotatably installed with connecting support plates 201; a power plate 202 is installed on the side end of the connecting support plate 201; a groove is provided on the side of the power plate 202, and the power plate 202 is slidably installed inside the mixer assembly 2; an air pump is installed on the outside of the mixer assembly 2, and a main flow pipe 203 is installed on the output end of the air pump; a collecting pipe 204 is installed on the side end of the main flow pipe 203; the side end of the collecting pipe 204 is connected to There is a diverter pipe 205; the diverter pipe 205 is equipped with evenly distributed air inlet pipes 206; the side ends of the air inlet pipes 206 are installed on the inner side of the mixer assembly 2; a return pipe 207 is also installed on the top of the mixer assembly 2; the lower end of the return pipe 207 is connected to the input end of the bottom of the air pump outside the mixer assembly 2; a drive cylinder is installed at the bottom of the mixer assembly 2, and a traction plate 208 is installed on the output end of the bottom of the drive cylinder; a telescopic sealing cover 2010 is installed at the bottom of the mixer assembly 2; a telescopic pipe 209 is installed in the middle position of the bottom of the telescopic sealing cover 2010; the telescopic pipe 209 passes through the traction plate 208;

[0053] Three openers 3 are also installed on the inner side of the support bracket 1; the top of the support bracket 2 101 is installed with a four-curtain web laying machine 301, a sliding guide rail 303, a three-stage hot air tunnel 306 and a surface treatment component 307 from back to front; the input end of the opener 3 is connected to the bottom of the telescopic tube 209, and the output end of the opener 3 is connected to the input end of the four-curtain web laying machine 301; an electrostatic component 302 is installed on the four-curtain web laying machine 301, and the output end of the four-curtain web laying machine 301 is connected to the side end of the sliding guide rail 303; a laser thickness gauge 305 is installed on one side of the five-zone gradient needling machine 304; the five-zone gradient needling machine 304, the three-stage hot air tunnel 306 and the surface treatment component 307 are distributed on the sliding guide rail 303 from front to back; a spray pipe 308 is installed inside the surface treatment component 307; and a CNC cutting machine 309 is also installed on the front end of the sliding guide rail 303.

[0054] In the embodiment of the present invention, fibers with different material parameters are stored in the three raw material storage boxes 102 on the top of the support bracket 1 respectively. The fibers in the first two raw material storage boxes 102 flow to the corresponding mixer components 2 below through the discharge pipe 103, and the fibers in the third raw material storage box 102 are subjected to cationic modification treatment in the surface modification treatment component 104, and are impregnated with a polydimethyldiallyl ammonium chloride solution with a mass fraction of 0.5%-1.0% to increase the surface charge density of the fibers and enhance the fiber entanglement force during acupuncture, so that the treated fibers fall into the third mixer component 2. The three mixer components 2 correspond to the upper, middle and lower fiber layers respectively, and the air pump on the outside of the mixer component 2 generates air. The air flows through the main pipe 203 to the inside of the collecting pipe 204 and then through the branch pipe 205 to the inside of each air inlet pipe 206. The inner end of the air inlet pipe 206 is on the same curved surface as the inner side wall of the mixer assembly 2. The air flow enters the groove on the side of the power plate 202, driving the power plate 202 and the connecting support plate 201 to rotate and mix the fibers. The excess air flow flows back to the air pump for recycling through the return pipe 207 with a filtering structure. Different materials are stored in the storage box 105. The first storage box 105 stores low-melting point adhesive fibers. The low-melting point adhesive fibers enter the first mixer assembly 2 through the guide pipe 106, making 30%-40% of the upper layer of the first mixer assembly 2 The fiber is mixed with 5%-10% low-melting point adhesive fiber. The functional filler of nano titanium dioxide is stored in the second storage box 105, and flows to the second protective mixer component 2 through the guide pipe 106 for mixing. The fibers in the mixer component 2 reduce the stirring force during mixing, reducing the breakage of the fibers. The driving cylinder at the bottom of the mixer component 2 drives the traction plate 208 to drive the telescopic tube 209 to move downward. The bottom of the telescopic tube 209 is folded together, and the telescopic tube 209 pulls the telescopic sealing cover 2010 to stretch into a conical structure, so that the mixed different fibers enter the interior of the opener 3 for processing. The speed of the fiber opening roller of the upper loose layer is 800-1000r / min, the opening time is 30-40s, and it is maintained The opening rollers for the lower dense layer of fibers rotate at a speed of 500-700 rpm for 50-60 seconds to avoid excessive damage to the fiber strength. The opened fibers then enter the four-curtain web laying machine 301 for layered and stacked laying. The electrostatic component 302 modifies the charge differences between the laid fibers, enhancing interlayer bonding and reducing delamination. The laid fibers then travel along the sliding guide 303 into the five-zone gradient needling machine 304 for needling. The three layers of fibers—the upper loose layer, the middle transition layer, and the lower dense layer—are divided into five zones and needled according to the needlepunching parameters. A laser thickness gauge 305 monitors the felt thickness in real time, adjusting the needlepunch pressure by 0.5-2.0MPa, ensuring a density gradient deviation of ≤5%. The needle-punched fibers then enter a three-stage hot air tunnel 306 for heating. A certain pressure is applied, heating the upper loose layer of fibers to 100-120°C, activating the local bonding of the low-melting-point fibers on the surface. The middle transition layer of fibers is kept warm to 120-140°C, promoting the bonding of functional fillers and fibers. The lower dense layer of fibers is cured at a temperature of 140-160°C to achieve deep entanglement of the dense fibers. A gradient pressure of 0.1-0.5MPa is applied, with the upper layer pressure parameter ≤ the middle layer pressure parameter ≤ the lower layer pressure parameter, further strengthening the density gradient structure. Differentiated surface treatment is then performed by the surface treatment assembly 307 and the spray pipe 308. The fibers are then precisely cut according to requirements using a CNC cutting machine 309, ensuring that the density distribution through the thickness meets the design requirements.

[0055] In the second embodiment, the fibers stored in the three raw material storage boxes 102 are mixed in the first mixer component 2 according to the fiber linear density of the upper loose layer of 1.2dtex / 30mm, 35% viscose fiber and 8% low melting point fiber in the storage box 105. The fiber linear density of the middle transition layer is 2.0dtex / 45mm, 35% viscose fiber and 12% nano titanium dioxide in the storage box 105 are mixed in the second mixer component 2. The fiber linear density of the lower dense layer is 3.0dtex / 60mm. After the modified treatment, it is put into the third mixer component 2 at 30% for processing, and then enters the four-curtain web laying machine 301 after passing through the opener 3. The fiber surface density of the upper loose layer is 25g / m², the fiber surface density of the middle transition layer is 40g / m², and the fiber surface density of the lower dense layer is 50g / m². The fiber then enters the five-zone gradient needling machine 304 and is processed according to the parameters of a needling density of 300 needles / cm² and a depth of 8mm in the lower dense zone. Finally, it passes through the three-stage hot air tunnel 306 with a lower layer temperature of 150°C and a pressure of 0.4MPa for heating to form a gradient density felt for air filtration with a density of 0.15g / cm³ for the upper layer → 0.25g / cm³ for the middle layer → 0.35g / cm³. The felt can filter 5μm particles with a filtration efficiency of 85% and 1μm particles with a filtration efficiency of 70%, which is 50% better than traditional uniform density materials.

[0056] In the third embodiment, the fibers stored in the three raw material storage boxes 102 are mixed in the first mixer component 2 according to the fiber linear density of the upper loose layer of 1.0dtex / 25mm, 40% viscose fiber and 10% chitosan modified fiber in the storage box 105. The fiber linear density of the middle transition layer is 1.8dtex / 40mm, 30% viscose fiber and 15% calcium alginate fiber in the storage box 105 are mixed in the second mixer component 2. The fiber linear density of the lower dense layer is 3.5dtex / 65mm, which is modified and then added to the third mixer component 2 at 25%. After processing, it passes through the opener 3 and then enters the four-curtain web laying machine 301. In the four-curtain web laying machine 301, the interlayer voltage of 8kV is applied through the electrostatic component 302 for 5s. Then it passes through the five-zone gradient needling machine 304 and the three-stage hot air tunnel 306 and enters the surface treatment component 307 for surface treatment. The upper layer softener concentration is 1.5%, and the lower layer waterproofing agent concentration is 0.8% to form a medical dressing with a moisture absorption rate of ≥15g / 100g in 20s for the upper layer, and a liquid permeability of ≤5% in 24h for the lower layer. The tensile strength is ≥8N / cm in the longitudinal direction and ≥5N / cm in the transverse direction to meet the mechanical requirements of different stages of wound healing.

[0057] The working principle of this embodiment is as follows: the insides of the three raw material storage boxes 102 respectively store fibers with different material parameters. The fibers inside the first two raw material storage boxes 102 flow to the corresponding mixer components 2 below through the discharge pipe 103, and the fibers in the third raw material storage box 102 are subjected to cationic modification and fall into the third mixer component 2. The three mixer components 2 correspond to the upper, middle and lower fiber layers respectively. The air flow generated by the air pump on the outside of the mixer component 2 flows into the collecting pipe 204 through the main pipe 203 and then is diverted to each air inlet pipe 206 through the diversion pipe 205 to drive the power plate 202 and the connecting support plate 201 to rotate to perform fiber mixing processing. The low-melting-point adhesive fiber stored in the first storage box 105 enters the first mixer component 2, and the second storage box 105 enters the first mixer component 2. The functional filler of nano titanium dioxide stored in the box 105 flows to the second protective mixer component 2 for mixing, and the driving cylinder drives the traction plate 208 to drive the telescopic tube 209 to move downward, pulling the telescopic sealing cover 2010 to stretch into a conical structure. The mixed different fibers enter the opener 3 for processing, so that the opened fibers enter the four-curtain laying machine 301 for layered and stacked laying. The laid fibers are modified by the electrostatic component 302 to enhance the interlayer bonding force due to the charge difference of the modified fibers. The fibers enter the five-zone gradient needling machine 304 along the sliding guide rail 303 for needling treatment, and the felt thickness is monitored in real time by the laser thickness gauge 305. The fibers then enter the three-section hot air tunnel 306 for heating treatment to form a solid felt, and are then accurately cut according to demand by the CNC cutting machine 309.

[0058] In this article, there are several points to note:

[0059] 1. The drawings of the embodiments of the present invention only relate to the structures related to the embodiments of the present invention. Other structures may refer to conventional designs.

[0060] 2. In the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to form new embodiments.

[0061] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A production process for viscose-based staple fiber felt with gradient density distribution, characterized in that: The following steps are involved: First, three raw material storage tanks (102) respectively store three types of viscose staple fibers with different physical parameters as gradient raw materials, and the three types of viscose staple fibers with different physical parameters are divided into an upper loose layer fiber, a middle transition layer fiber, and a lower dense layer fiber; Second, three mixer components (2) are used to achieve three kinds of gradient raw material pre-distribution respectively, 30%-40% of the upper loose layer fiber is mixed with 5%-10% of the low melting point adhesive fiber, 30%-40% of the middle loose layer fiber is mixed with 10%-15% of the functional filler, and 30%-40% of the lower dense layer fiber is processed separately, and then the opening degree of the different layers of fibers is controlled by the opener (3); Third, a four-curtain laying machine (301) is used to lay a three-layer superimposed web, and a 5-10 kV electrostatic field is applied between the upper loose layer fiber, the middle transition layer fiber, and the lower dense layer fiber to enhance the interlayer bonding force by utilizing the charge difference of the modified fiber; Fourth, a five-zone gradient needling machine (304) is used to independently control the needling parameters of each zone, and the pressure of the five-zone gradient needling machine (304) is adjusted in a coordinated manner by online real-time monitoring of the felt thickness to ensure that the density gradient deviation is ≤5%; Fifth, a three-stage hot air tunnel (306) is used to perform heating treatment in layers; Sixth, using a CNC cutting machine (309), accurately cutting according to the density gradient curve of the target product; The three raw material storage boxes (102) in step 1 are arranged horizontally from left to right. The first raw material storage box (102) stores the upper loose layer fibers with a linear density of 1.0-1.5 dtex, a length of 25-35 mm, and a breaking strength of ≥2.5 cN / dtex. The second raw material storage box (102) stores the middle transition layer fibers with a linear density of 1.5-2.5 dtex, a length of 35-50 mm, and a breaking strength of ≥3.0 cN / dtex. The third raw material storage box (102) stores the lower dense layer fibers with a linear density of 2.5-3.5 dtex, a length of 50-65 mm, and a breaking strength of ≥3.5 cN / dtex. A surface modification treatment component (104) is installed below the third raw material storage box (102). The surface modification treatment component (104) treats the lower dense layer fibers by dipping them in a polydimethyldiallyl ammonium chloride solution with a mass fraction of 0.5%-1.0%. The fibers are subjected to cationic modification treatment; the four-curtain laying machine (301) in step three lays the upper loose layer fibers, the middle transition layer fibers and the lower dense layer fibers respectively, the lower dense layer fibers are laid at the bottom, the laying speed of the lower dense layer fibers is 5-10m / min, the surface density is 40-60g / m², the fiber orientation is ≥60°, and then the middle transition layer fibers are laid, and the laying speed of the middle transition layer fibers is 10-15m / min. min, surface density 30-50g / m², fiber orientation 40°-50°, the upper loose layer of fibers is laid on the top, the laying speed of the upper loose layer of fibers is 15-20m / min, the fiber web surface density 20-30g / m², the fiber orientation ≤30°, the four-curtain laying machine (301) adopts layered laying combined with electrostatic adsorption technology to achieve a gradient distribution of fiber orientation 20°-70° and surface density 20-60g / m².

2. The production process of viscose-based staple fiber felt with gradient density distribution according to claim 1, characterized in that: The five-zone gradient needling machine (304) in step 4 includes a five-zone independent control system, and the needling density ranges from 80 to 350 needles / cm 2 , the depth changes gradually from 5 to 22 mm.

3. The production process of viscose-based staple fiber felt with gradient density distribution according to claim 2, characterized in that: The three-stage hot air tunnel (306) in step five processes the upper loose layer fibers, the middle transition layer fibers and the lower dense layer fibers respectively, the upper loose layer fibers are heated to 100-120°C, the surface low melting point fibers are activated for local bonding, the middle transition layer fibers are kept warm at 120-140°C, and the lower dense layer fibers are cured and heated to 140-160°C, and a gradient pressure of 0.1-0.5 MPa is applied during the shaping process.

4. A production equipment for realizing the production process of viscose-based staple fiber felt with gradient density distribution according to any one of claims 1 to 3, characterized in that: The bottoms of the three raw material storage boxes (102) are mounted on the top of the support bracket one (1); the bottom of one side of the support bracket one (1) is mounted with the support bracket two (101); the bottoms of the three raw material storage boxes (102) are all mounted with discharge pipes (103); the discharge pipes (103) are mounted with control valves, and the discharge pipe (103) at the bottom of the third raw material storage box (102) is mounted with a surface modification treatment component (104); and the side of the raw material storage box (102) is mounted with a storage box (105).

5. The production equipment according to claim 4, characterized in that Different processing materials are stored inside the storage box (105), and a guide tube (106) is installed at the bottom of the storage box (105), wherein a control valve is installed on the guide tube (106); three mixer assemblies (2) are installed on the top of the inner side of the support bracket (1); the tops of the three mixer assemblies (2) are respectively connected to the discharge pipe (103) and the bottom of the guide tube (106), and connecting support plates (201) are rotatably installed at the upper and lower ends of the mixer assembly (2).

6. The production equipment according to claim 5, characterized in that A power plate (202) is mounted on the side end of the connecting support plate (201); a groove is provided on the side of the power plate (202), and the power plate (202) is slidably mounted inside the mixer assembly (2); an air pump is mounted on the outside of the mixer assembly (2), and a main flow pipe (203) is mounted on the output end of the air pump; a collecting pipe (204) is mounted on the side end of the main flow pipe (203); a diverter pipe (205) is connected to the side end of the collecting pipe (204); and evenly distributed air intake pipes (206) are mounted on the diverter pipe (205).

7. The production equipment according to claim 6, characterized in that The side end of the air inlet pipe (206) is mounted on the inner side of the mixer assembly (2); a return pipe (207) is also mounted on the top of the mixer assembly (2); the lower end of the return pipe (207) is connected to the input end of the bottom of the air pump outside the mixer assembly (2); a driving cylinder is mounted on the bottom of the mixer assembly (2), and a traction plate (208) is mounted on the output end of the bottom of the driving cylinder; a telescopic sealing cover (2010) is mounted on the bottom of the mixer assembly (2); a telescopic tube (209) is mounted in the middle of the bottom of the telescopic sealing cover (2010); and the telescopic tube (209) passes through the traction plate (208).

8. The production equipment according to claim 7, characterized in that Three opening machines (3) are also installed on the inner side of the support bracket 1 (1); the top of the support bracket 2 (101) is installed with a four-curtain type net laying machine (301), a sliding guide rail (303), a three-stage hot air tunnel (306) and a surface treatment component (307) in sequence from back to front; the input end of the opening machine (3) is connected to the bottom of the telescopic tube (209), and the output end of the opening machine (3) is connected to the input end of the four-curtain type net laying machine (301); the four-curtain type net laying machine (301) is installed with an electrostatic component (302 ), and the output end of the four-curtain web laying machine (301) is connected to the side end of the sliding guide rail (303); a laser thickness gauge (305) is installed on one side of the five-zone gradient needling machine (304); the five-zone gradient needling machine (304), the three-section hot air tunnel (306) and the surface treatment component (307) are distributed on the sliding guide rail (303) from back to front; a spray pipe (308) is installed inside the surface treatment component (307); and a CNC cutting machine (309) is also installed on the front end of the sliding guide rail (303).

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