High-temperature-resistant pps net for wet pulp spreading and preparation method thereof

Abstract

This invention relates to the field of supporting materials for papermaking machinery, and discloses a high-temperature resistant PPS wire mesh for wet pulp spreading and its preparation method. The device includes a support skeleton layer woven from PPS monofilaments, and a hydrophilic functional layer anchored to its surface by hot rolling; the functional layer is composed of PPS ultrafine fibers modified with sodium 1-naphthalenesulfonate. The preparation method includes steps such as modified masterbatch preparation, melt-blown layering, skeleton weaving, and hot rolling composite. This invention reduces interfacial tension, improves dewatering efficiency and paper sheet uniformity, and enables the scrapped wire mesh to possess controlled pulping characteristics, achieving closed-loop utilization of PPS resources.

Description

Technical Field

[0001] This invention belongs to the field of supporting materials for papermaking machinery, specifically relating to a high-temperature resistant PPS mesh for wet pulp spreading and its preparation method. Background Technology

[0002] Existing high-performance PPS wire meshes are typically manufactured using a monofilament weaving process. The high modulus of PPS material maintains the dimensional stability of the wire mesh during long-term, high-speed operation, thus ensuring the continuity of paper sheet laying. However, the molecular chain structure of PPS resin lacks strongly polar functional groups, resulting in high chemical inertness and hydrophobic properties. When wet pulp comes into contact with the PPS wire mesh surface, the pulp's wettability is poor, making it difficult for the liquid phase to form a uniform liquid film on the wire surface.

[0003] This lack of microscopic wettability leads to the non-uniform enrichment of fine fibers and inorganic fillers at the solid-liquid interface, easily causing uneven pulp distribution during the initial formation stage on the wire. Due to poor wettability, water encounters significant surface tension resistance when passing through the mesh, affecting not only dewatering efficiency but also causing differences in physical properties between the front and back of the paper sheet, and even producing persistent wire marks. To improve surface wettability, conventional methods often employ physical coating or chemical grafting processes. However, these surface-modified layers are prone to peeling under the scouring and mechanical wear of high-speed papermaking machines, resulting in rapid failure and the potential for the peeled coating particles to become new contaminants, affecting the purity of the paper.

[0004] Currently, PPS papermaking wire, after reaching its service life or experiencing partial wear and tear, is mostly disposed of as non-degradable industrial solid waste through landfill or simple incineration due to its tight weave structure and relatively simple material composition. This linear production-use-disposal model results in resource waste. Although PPS material itself has recycling potential, its high melting point and the difficulty in easily returning it to a reprocessable state make its resource recycling extremely costly and inefficient. Summary of the Invention

[0005] To address the technical problems of existing PPS paper forming wires and dry wires, such as poor pulp wettability due to strong surface hydrophobicity, uneven distribution of fine fibers and fillers, high dewatering resistance, and low resource utilization rate of scrapped materials, this invention provides a high-temperature resistant PPS wire for wet pulp spreading and its preparation method.

[0006] This invention provides a high-temperature resistant PPS mesh for wet pulp spreading, the overall structure of which is composed of a high-strength support skeleton layer and a surface hydrophilic functional layer. The high-strength support skeleton layer is composed of a mesh fabric formed by weaving PPS monofilaments. The diameter of the PPS monofilaments is set between 0.2 mm and 0.8 mm, its breaking strength is greater than 4.5 cN / dtex, and its heat shrinkage rate at 200℃ is less than 1.5%. The surface hydrophilic functional layer is an ultrafine fiber nonwoven layer prepared by modifying PPS resin. The average fiber diameter distribution within this nonwoven layer is in the range of 1 μm to 5 μm, and its areal density is set at 20 g / m³. 2 Up to 100g / m 2 The surface hydrophilic functional layer is anchored to at least one side of the high-strength support skeleton layer through a thermophysical bonding interface, forming a composite network with a multi-scale porous structure.

[0007] The PPS monofilaments in the high-strength support skeleton layer have a molecular weight distribution index of 2.0 to 3.5 and a melting point of 280°C to 285°C. These monofilaments undergo a multi-stage stretching process before weaving, with the ratio controlled between 3.5 and 5.5 times. The weaving process employs plain weave, twill weave, or multi-warp and weft weave structures, with a warp density of 200 to 500 threads / 10cm and a weft density of 150 to 400 threads / 10cm. The air permeability of the high-strength support skeleton layer is controlled between 100 cfm and 800 cfm to ensure good drainage performance when used as the main support structure.

[0008] The modified PPS resin used in the surface hydrophilic functional layer comprises PPS base chips, a hydrophilic melt index modifier, and an antioxidant stabilizer. The hydrophilic melt index modifier is selected from sodium 1-naphthalenesulfonate, and its mass percentage content in the modified PPS resin is 1.5% to 5.0%. Sodium 1-naphthalenesulfonate has a strong polar characteristic of sulfonic acid groups, which can induce local orientation changes in molecular chains within the PPS matrix through ion-dipole interactions and reduce the viscosity of the PPS melt. The modified PPS resin exhibits a melt index between 100 g / 10 min and 600 g / 10 min at 300°C and a 5 kg load, representing an improvement in melt index compared to the unmodified PPS matrix. This abrupt change in melt index allows the material to form ultrafine fibers with higher aspect ratios during meltblowing or spunbonding processes.

[0009] In a preferred embodiment of the present invention, the surface hydrophilic functional layer possesses controllable pulping characteristics. The introduction of sodium 1-naphthalenesulfonate alters the crystallization kinetics of PPS, resulting in the formation of numerous micro-amorphous regions and grain boundary defects within the ultrafine fibers. When the composite mesh is discarded, under a high-temperature alkaline hydrothermal environment (temperature 130°C to 160°C, pH 10 to 13), the fiber structure of the surface hydrophilic functional layer swells. Combined with a mechanical high-shear pulping process, it can rapidly dissociate into PPS pulp with a length of 0.5 mm to 2.5 mm and a richly branched structure, thereby achieving the resource-based regeneration of waste mesh materials.

[0010] This invention further provides a method for preparing the above-mentioned high-temperature resistant PPS mesh for wet pulp spreading, the method specifically including the following steps: The first step is the preparation of hydrophilic modified PPS masterbatch. First, PPS base chips are dried in a vacuum oven at 140℃ to 160℃ for 4 to 8 hours until their moisture content is below 50 ppm. The dried PPS base chips, along with dehydrated 1-naphthalenesulfonate powder and hindered phenolic antioxidants, are added to a high-speed mixer in a predetermined ratio and mixed at 500 rpm to 800 rpm for 10 to 20 minutes. The mixture is then fed into a co-rotating twin-screw extruder for melt extrusion shearing. The temperatures of zones one through ten of the extruder are set as follows: Zone one 150-180℃, Zone two 240-260℃, Zones three through eight 275-290℃, Zones nine through ten 260-275℃. The screw speed is 300 rpm to 500 rpm, achieving nanoscale dispersion of 1-naphthalenesulfonate in the PPS matrix through high shear force. The extruded strips are cooled with water, air-dried, and pelletized to obtain hydrophilic modified PPS masterbatch.

[0011] The second step involves the preparation of the microfiber nonwoven layer. The hydrophilic modified PPS masterbatch obtained in the first step is blended with ordinary PPS chips at a mass ratio of 1:2 to 1:5 and then dried. Using a melt-blowing forming system, the blend is fed into a single-screw extruder for melting, with the extrusion temperature controlled at 285℃ to 310℃. The melt is extruded through a spinneret equipped with a micro-orifice array, the micro-orifice diameter of which is 0.1mm to 0.3mm. Simultaneously, a high-pressure hot air stream with a pressure of 0.1MPa to 0.4MPa and a temperature of 300℃ to 330℃ is introduced to rapidly draw the melt stream. The drawn microfibers are then randomly deposited onto a receiving curtain under the action of a negative pressure suction device, forming a preliminary hydrophilic functional layer preform with uniform surface density.

[0012] The third step is the preparation of the woven skeleton layer. PPS monofilaments are used as warp and weft threads and woven on a heavy-duty loom according to a pre-set weave structure. The weaving tension is controlled at 50N to 150N per centimeter of fabric width to ensure the regularity of the mesh shape. After weaving, the mesh is preheated and shrunk at 220℃ to 240℃ using a heat-setting machine to stabilize the mesh dimensions.

[0013] Step four: Composite and interface anchoring. The hydrophilic functional layer preform prepared in step two is laid on the surface of the high-strength support skeleton layer prepared in step three. The laminated material is then fed into a multi-roll hot rolling mill. The surface temperature of the hot rolling rolls is set to 265°C to 275°C, which is above the glass transition temperature of PPS and close to its initial melting temperature, causing the microfibers to be in a semi-molten state at the contact points. The hot rolling pressure is set to 1.0 MPa to 5.0 MPa, and the hot rolling speed is 2 m / min to 10 m / min. Under the combined action of hot and pressure, the microfibers are partially embedded in the gaps between the monofilaments of the support skeleton layer, forming a microscopically interlocked structure on the surface of the monofilaments.

[0014] The fifth step is post-processing and winding. The laminated mesh enters a circulating air heat setting chamber and is held at 200℃ for 30 to 60 seconds to eliminate internal stress generated during the lamination process. After cooling by cold rollers, online defect detection and edge trimming are performed, and finally, it is wound into finished products according to specifications.

[0015] In the above preparation process, the treatment of sodium 1-naphthalenesulfonate in the first step must be carried out under vacuum at 100°C until the moisture content is below 100 ppm to prevent hydrolytic degradation of PPS resin due to moisture during high-temperature extrusion. The length-to-diameter ratio of the twin-screw extruder is preferably 40 to 48, and by setting up multiple kneading block combinations, the peeling and coating effect on polar additives is enhanced.

[0016] In the second step of meltblowing, the receiving distance is a core parameter for adjusting the porosity of the microfiber layer. In this invention, the receiving distance is set to 150mm to 350mm. When the receiving distance is short, the fibers still have residual heat when they reach the receiving curtain, which is conducive to the formation of self-adhesive points between fibers and improves the overall strength of the nonwoven layer. When the receiving distance is long, the fibers are fully cooled, and the resulting nonwoven layer is more fluffy, which is beneficial to increasing the dust holding capacity and water absorption buffering capacity of the composite web.

[0017] In the fourth-step composite process, the surface morphology of the hot-rolled rolls has a significant impact on the quality of the finished product. It is preferable to pair steel rolls with micro-pitted textures with flat rubber rolls. The depth of the micro-pitted texture is 0.1mm to 0.3mm, which ensures interfacial bonding strength while avoiding excessive compaction that could reduce the hydrophilic flux of the nonwoven layer. Interfacial bonding strength is controlled by maintaining the peel force between 5N / 25mm and 15N / 25mm, ensuring no delamination under high-speed paper machine washing and providing the possibility of mechanical peeling and recycling after disposal.

[0018] The working principle of the high-temperature resistant PPS mesh for wet pulp spreading of the present invention is as follows: During the wet pulp spreading stage, the surface hydrophilic functional layer contains a large number of sodium sulfonate polar groups, resulting in an excellent hydrophilic-oleophilic balance. When the wet pulp is sprayed onto the mesh surface, the aqueous phase can quickly spread on the surface of the microfibers, reducing the static contact angle from over 90 degrees in ordinary PPS meshes to below 40 degrees. This good wettability eliminates air bubble retention in the pulp and guides the fine fibers and fillers to be uniformly positioned in the micropores formed by the microfiber layer, avoiding excessive loss to the bottom of the mesh or accumulation in dead zones at the interlacing points of the monofilaments. Since the diameter of the microfibers in the surface layer is much smaller than the diameter of the monofilaments supporting the skeleton, the filtration accuracy of the mesh is improved, thereby increasing the uniformity and tensile strength of the paper sheet. During dewatering, the hydrophilic interface reduces the interfacial resistance of water molecules passing through the pores, resulting in an increased dewatering rate of the mesh under the same negative pressure conditions.

[0019] The recycling principle of the composite web described in this invention lies in the fact that, due to the specific modification technology employed in the surface hydrophilic functional layer, its chemical stability threshold is lower than that of the skeleton layer under certain conditions. When the web is scrapped, the hydrophilic functional layer is first separated from the skeleton layer through physical peeling or a combination of solvent swelling and mechanical shearing. The separated hydrophilic functional layer contains a high content of sulfonic acid groups, which exhibit better dispersibility in hot water than ordinary PPS. Pretreatment in a high-concentration alkaline solution allows the solution to rapidly penetrate the fiber interior due to the occupancy effect of sodium 1-naphthalenesulfonate at the crystal edges. Subsequently, after processing in a disc refiner or high-energy hydraulic refiner, the ultrafine fibers peel off axially and radially, forming a large amount of microfibrillated PPS pulp. This pulp has an extremely high specific surface area and can be reused as a functional additive in the production of flame-retardant paper, heat-insulating paper, or special filter membranes, thus achieving a closed-loop utilization of the expensive PPS resource.

[0020] As a further refinement of the present invention, the thickness of the surface hydrophilic functional layer is set to be between 0.05 mm and 0.20 mm. If the thickness is less than 0.05 mm, the interception effect on fine fibers in the slurry is not obvious, and the wear resistance margin is insufficient; if the thickness is greater than 0.20 mm, it may increase the overall thickness of the mesh, resulting in excessive hydraulic impact resistance during return-side cleaning.

[0021] As a further refinement of the present invention, the surface of the monofilaments of the high-strength support skeleton layer can be pre-treated with plasma activation. The treatment power is controlled between 500W and 2000W, and the treatment time is between 1 second and 10 seconds. Through plasma bombardment, a micro-roughened morphology and active free radicals are formed on the surface of the monofilaments, further enhancing the chemical bonding and physical interlocking forces with the surface hydrophilic functional layer during hot rolling, ensuring that the composite interface does not delaminate in a high-temperature and humid environment above 200°C.

[0022] The proportions of each component and the process parameters involved in this invention have all been verified through systematic engineering experiments. By adjusting the amount of sodium 1-naphthalenesulfonate added, the hydrophilicity rate and pulping difficulty of the surface layer can be precisely controlled to meet the different requirements of different paper types (such as aramid paper, glass fiber paper, and electrolytic paper) for the forming wire.

[0023] To address the chemical environment during wet pulp spreading, the PPS base chips used in this invention undergo acid washing treatment, resulting in a total residual metal ion content (such as sodium, calcium, and magnesium ions) of less than 500 ppm. This low metal ion content inhibits polymer degradation caused by ion catalysis under high-temperature hydrothermal conditions, ensuring the composite mesh's tolerance during spreading of strongly alkaline or acidic pulps and extending equipment maintenance cycles.

[0024] Regarding the precise control of the manufacturing process, this invention imposes strict requirements on the cooling rate of the heat-setting section. From the 240°C heat-setting zone to the winding zone, the cooling rate of the wire is controlled at 10°C to 20°C per second. Through this controlled cooling process, the PPS molecular chains can be guided to form fine and uniform spherulites during crystallization, increasing the modulus and hardness of the wire, thereby enhancing its wear resistance on the paper machine's wire section.

[0025] In the meltblown fabrication of the hydrophilic functional layer, the uniformity error of the orifice distribution of the spinneret is less than 1%. To ensure the uniformity of air permeability of the ultrafine fiber layer, a distribution channel is provided inside the spinneret to ensure that the pressure fluctuation of the melt in the entire width direction is less than 0.5%. This high-precision process control ensures that the composite wire prepared by this invention can guarantee the basis weight consistency and quality stability of the entire paper sheet when used on a wide paper machine.

[0026] The specific process for pulping composite mesh after it has been scrapped is as follows: The waste mesh is mechanically crushed into fragments of 10mm × 10mm. The fragments are then added to a reactor, along with a 5% to 10% sodium hydroxide solution. The mixture is heated to 150℃ and maintained under pressure, and stirred for 2 hours. This process maximizes the effect of sodium 1-naphthalenesulfonate, inducing numerous microcracks in the ultrafine fibers. The material is then pumped into a hydraulic fiber separator, where it undergoes high-energy collision and shearing at 3000 to 5000 rpm. At this point, because the supporting skeleton monofilaments are coarse and unmodified, they maintain high chemical stability, with only slight surface erosion; while the ultrafine fibers of the hydrophilic functional layer on the surface rapidly dissociate. Multi-stage vibrating screening separates the coarse monofilament fragments from the ultrafine pulp. The monofilament fragments can be recycled as general-grade PPS raw material for granulation, while the ultrafine pulp is used as a special functional fiber in the pulp mixing system.

[0027] In this invention, the woven structure of the high-strength support skeleton layer is not limited to a single layer; depending on the actual load of the paver, a double-layer or triple-layer woven structure can be adopted. For multi-layer structures, the layers are bound together by interlayer connecting warp threads to ensure overall rigidity. In this case, the surface hydrophilic functional layer is still composited on the top layer that directly contacts the pulp, playing a functional guiding role.

[0028] In the technical solution provided by this invention, the hot rolling temperature is selected between 265℃ and 275℃, based on the results of dynamic thermodynamic analysis of PPS. Within this temperature range, the PPS monofilaments maintain sufficient storage modulus to prevent structural collapse, while the surface-modified microfibers, due to their high melt index and suppressed crystallinity, have entered a viscous or quasi-viscous flow state on their surface layer, thus achieving cross-interface molecular chain entanglement within a very short pressing time. The pressure is selected between 1.0MPa and 5.0MPa to preserve the microporosity within the nonwoven layer while achieving interfacial anchoring, preventing the mirror effect caused by excessive compaction from affecting the slurry's web adhesion.

[0029] To enhance the chemical stability of the surface hydrophilic functional layer under extreme humid and hot environments, the modified masterbatch component may further include 0.2% to 0.8% by mass of a carbodiimide anti-hydrolysis agent. The carbodiimide groups can react with the trace amounts of terminal carboxyl groups or degradation products that may be generated during PPS thermal processing, blocking the degradation chain and ensuring improved strength retention of the composite mesh under saturated steam conditions above 150°C.

[0030] In the implementation of the composite process, to further precisely control the physical properties of the surface functional layer, this invention employs an online infrared thermometer to monitor the surface of the hot rolling roll at multiple points in real time, and combines this with an electromagnetic induction heating system to control the temperature difference of the roll surface within ±1℃. This precise temperature control system is crucial for ensuring the consistency of interfacial bonding during large-scale continuous production.

[0031] The high-temperature resistant PPS wire mesh for wet pulp spreading described in this invention has a final tensile strength of 40kN / m to 100kN / m, meeting the mechanical strength requirements of all high-speed paper machines for forming and drying wires. Due to the presence of a hydrophilic surface layer, its filtration level can reach 10μm to 30μm, far superior to the 100μm precision of traditional woven wire mesh. This multi-scale, graded filtration structure ensures efficient drainage while improving the recovery rate of fine fibers.

[0032] The PPS mesh and its preparation method described in this invention can be fine-tuned according to different slurry characteristics in practical engineering applications. For example, for slurries containing a large amount of synthetic fibers, the pore distribution of the surface functional layer can be made to exhibit a gradient change by fine-tuning the melt-blowing process parameters, i.e., the pore diameter is larger near the skeleton side and smaller near the slurry side. This gradient structure can further optimize the drainage dynamics process and prevent fine fibers from mechanically clogging the mesh.

[0033] In the first step of the preparation method, the vacuum level of the twin-screw extruder should be maintained below -0.09 MPa to force the discharge of volatiles and byproducts that may be generated during the melt mixing process. This ensures the purity of the obtained modified masterbatch and avoids filament breakage or injection holes during the subsequent microfiber forming process.

[0034] In the third weaving step, the PPS monofilaments used can be pre-modified, such as by impregnating them with a coupling agent solution of a specific polarity, to further enhance their compatibility with the surface nonwoven layer. The selected coupling agent should have high-temperature resistance and not decompose at 280°C, thereby forming a transition layer of molecular-level thickness on the monofilament surface.

[0035] After the fourth step of hot rolling composite bonding, in order to verify the quality of the interface bonding, samples are taken every 1000 meters produced for peel force test and circulating water scouring simulation test. Under the simulated high-pressure water jet scouring at a flow rate of 50L / min and a pressure of 0.5MPa, there should be no obvious blistering or peeling of the surface hydrophilic functional layer, which proves the reliability of the interface anchoring process of the present invention.

[0036] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention introduces the polar monomer sodium 1-naphthalenesulfonate into the molecular chain of PPS and combines it with meltblown ultrafine fiberization technology. While maintaining the high temperature resistance and corrosion resistance of PPS, it improves the distribution of wet pulp in the early stage of spreading, enhances the uniformity of the finished paper, and also improves the dewatering efficiency by reducing interfacial tension, thereby reducing the energy load of the drying section of the paper machine. 2. The high-strength support skeleton layer ensures the dimensional stability and service life of the mesh under high temperature, high tension and high shear force conditions; while the surface hydrophilic functional layer specifically solves the problem of interfacial interaction in the slurry-water separation process, avoiding the defects of traditional surface coatings that are easy to peel off and not wear-resistant, and maintaining the stability of the functional layer throughout its entire life cycle. 3. By utilizing the pulping properties of modified PPS resin under specific chemical and mechanical action, the composite mesh provided by this invention can be transformed into high-value PPS pulp after it is scrapped, rather than being treated as industrial waste, thereby improving the use value and economic benefits of PPS materials. Detailed Implementation

[0037] This invention provides a high-temperature resistant PPS mesh for wet pulp spreading and its preparation method. The core of this invention lies in solving the deep-seated contradictions of insufficient wettability, high dewatering resistance, and difficulty in closed-loop utilization of waste resources in PPS materials under extreme humid and hot industrial environments through the coupling of microscopic molecular-level modification and macroscopic multi-scale composite structures. The high-temperature resistant PPS mesh for wet pulp spreading of this invention is based on a two- or multi-layer integrated composite logic, consisting of a high-strength support skeleton layer and a surface hydrophilic functional layer anchored through a precise thermophysical interface. In this architecture, the high-strength support skeleton layer serves as the main load-bearing and structural stability unit, and its physical composition is based on a precision-woven fabric of high-performance PPS monofilaments. These PPS monofilaments undergo rigorous raw material screening before production, with the molecular weight distribution index of the base resin precisely controlled between 2.0 and 3.5. This range ensures that the monofilaments can form highly oriented crystalline regions during subsequent multi-stage drawing processes, thereby improving the tensile strength of the monofilaments.

[0038] The technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples, so as to ensure that those skilled in the art can fully understand and implement the present invention.

[0039] Example 1: By weight percentage, high-strength support skeleton layer (PPS monofilament diameter 0.5mm, breaking strength 5.2cN / dtex, heat shrinkage rate at 200℃ 1.2%, molecular weight distribution index 2.8, subjected to 3.8 times multi-stage stretching; plain weave, warp density 350 threads / 10cm, weft density 280 threads / 10cm, air permeability 450cfm); Surface hydrophilic functional layer (modified PPS microfiber, average diameter 3μm, areal density 60g / m³)2 Thickness 0.12mm; modified PPS resin contains 3.0% sodium 1-naphthalenesulfonate, melt index 350g / 10min at 300℃ / 5kg, and 0.5% carbodiimide anti-hydrolysis agent. Composite parameters (hot rolling temperature 270℃, pressure 3.0MPa, interfacial peel force 10N / 25mm). Preparation steps: S1: Preparation of hydrophilic modified PPS masterbatch: PPS base chips are vacuum dried at 150℃ for 6 hours until the moisture content is 40ppm; mixed with dried sodium 1-naphthalenesulfonate and antioxidant, and fed into a twin-screw extruder with a length-to-diameter ratio of 45:1. The temperature is 165℃ in zone 1, 250℃ in zone 2, 285℃ in zones 3 to 8, and 270℃ in zones 9 to 10. The screw speed is 400rpm and the vacuum extrusion is -0.095MPa. The masterbatch is then pelletized to obtain the modified masterbatch. S2: Preparation of ultrafine fiber nonwoven layer, modified masterbatch and ordinary PPS chips are blended and dried at 1:3; extruded at 295℃ in meltblown forming system, with spinneret micro-orifice diameter of 0.2mm, high-pressure hot air flow pressure of 0.25MPa, temperature of 315℃, receiving distance of 250mm, to deposit and form hydrophilic functional layer preform. S3: Preparation of the braided skeleton layer, PPS monofilament is treated with 800W plasma for 3 seconds, woven on a heavy-duty loom (tension 80N / cm fabric width), and preheated and shrunk at 230℃; S4: Composite and interface anchoring, functional layer blank is laid on the surface of skeleton layer, multi-roll hot rolling composite machine (with micro-pit textured steel roller + flat rubber roller, micro-pit depth 0.2mm), 270℃, 3.0MPa, 5m / min composite; S5: Post-processing and winding, 200℃ circulating hot air setting for 45 seconds, cooling at a rate of 15℃ / s, winding after inspection.

[0040] Example 2: The modified PPS resin contained 1.5% sodium 1-naphthalenesulfonate and had a melt index of 120 g / 10 min. The remaining components and proportions were the same as in Example 1. Preparation steps: Same as in Example 1.

[0041] Example 3: The modified PPS resin contained 5.0% sodium 1-naphthalenesulfonate and had a melt index of 580 g / 10 min. The remaining components and proportions were the same as in Example 1. Preparation steps: Same as in Example 1.

[0042] Example 4: The surface hydrophilic functional layer has an average diameter of 1 μm for the ultrafine fibers, and the remaining components and proportions are the same as in Example 1; Preparation steps: The meltblown receiving distance is 320mm, and the remaining steps are the same as in Example 1.

[0043] Example 5: The surface hydrophilic functional layer has an average microfiber diameter of 5 μm, and the remaining components and proportions are the same as in Example 1; Preparation steps: The meltblown receiving distance is 180mm, and the remaining steps are the same as in Example 1.

[0044] Example 6: Same as Example 1; Preparation steps: hot rolling composite temperature 265℃, the remaining steps are the same as in Example 1.

[0045] Example 7: Same as Example 1; Preparation steps: hot rolling composite temperature 275℃, the remaining steps are the same as in Example 1.

[0046] Example 8: Modified masterbatch and ordinary PPS chips were blended at a ratio of 1:5, with the remaining components and proportions the same as in Example 1; Preparation steps: Same as in Example 1.

[0047] Comparative Example 1: The surface functional layer is made of unmodified PPS microfiber, without sodium 1-naphthalenesulfonate, and the other components are the same as in Example 1; Preparation steps: The preparation of modified masterbatch was cancelled, and the functional layer was prepared directly by melt-blowing ordinary PPS chips. The remaining process parameters and steps were the same as in Example 1.

[0048] Comparative Example 2: Only a PPS monofilament braided skeleton layer, without a surface hydrophilic functional layer, and the other components are the same as in Example 1; Preparation steps: The functional layer preparation and composite steps are omitted, and the remaining process parameters and steps are the same as in Example 1.

[0049] Test method: Hydrophilicity test: Measure the static contact angle of the surface to evaluate the wetting effect; Dewatering efficiency test: Simulate papermaking conditions, measure the dewatering rate per unit time, and calculate the efficiency ratio with ordinary PPS wire. Paper uniformity test: detects the basis weight deviation rate of the paper after it has been laid out; Mechanical property testing: Determine the tensile strength and interfacial peel force of the composite mesh; High temperature resistance test: Hold at 200℃ for 1000 hours and determine the strength retention rate; Pulping test: PPS pulp yield was determined by hydrothermal treatment with sodium hydroxide solution at 150℃ and pH 12 + shearing at 4000 rpm. Filtration performance test: Determine the filtration accuracy of the composite mesh (efficiency in retaining 10μm particles).

[0050] The test data comparisons are shown in Table 1 and Table 2.

[0051] Table 1 Comparison of Static Contact Angle, Dehydration Rate, and Interfacial Peel Force

[0052] Table 2 Comparison of 200℃ Strength Retention Rate, Pulp Yield, Paper Basis Weight Deviation Rate, and Filtration Accuracy

[0053] Examples 1 to 8 utilize sodium 1-naphthalenesulfonate to introduce polar groups to enhance hydrophilicity, ultrafine fibers to construct multi-scale pores to reduce dehydration resistance, and modified resins to impart controlled pulping properties. Comparative Example 1, lacking sodium 1-naphthalenesulfonate modification, exhibits extremely poor hydrophilicity and recyclability; Comparative Example 2, lacking a hydrophilic functional layer, shows decreased dehydration and filtration performance.

[0054] When the sodium 1-naphthalenesulfonate content is 3.0% to 5.0%, the fiber diameter is 3μm to 5μm, and the hot rolling temperature is 270℃ to 275℃, the overall performance is better. Among them, the sodium 1-naphthalenesulfonate content determines the hydrophilicity and pulping efficiency, the fiber diameter affects the filtration accuracy and dewatering rate, and the hot rolling temperature controls the interfacial bonding strength. The three factors work together to ensure the overall performance of PPS mesh.

[0055] Compared to Comparative Example 1 without modification, the static contact angle of the embodiments is reduced by more than 59%, the dewatering rate is increased by more than 102%, and the pulp yield is increased by more than 157%. Compared to Comparative Example 2 without functional layer, the dewatering rate is increased by more than 124%, the basis weight deviation rate of paper is reduced by more than 73%, and the filtration accuracy is increased by more than 26%, meeting the requirements of efficient spreading and green production of specialty paper.

[0056] In summary, this invention achieves simultaneous improvement in hydrophilicity, dewatering efficiency, and recyclability by coupling sodium 1-naphthalenesulfonate modification with ultrafine fiber composite process, solving the core pain points of traditional PPS mesh, and is suitable for efficient wet pulp spreading scenarios, with good potential for industrialization.

[0057] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-temperature resistant PPS mesh for wet pulp spreading, characterized in that, Its overall structure is composed of a high-strength supporting skeleton layer and a surface hydrophilic functional layer through a thermophysical interface; The high-strength support skeleton layer is composed of a mesh fabric formed by weaving PPS monofilaments, the diameter of which is 0.2mm-0.8mm. The surface hydrophilic functional layer is an ultrafine fiber nonwoven layer prepared by modifying PPS resin, and the average diameter of the fibers inside the nonwoven layer is distributed in the range of 1μm-5μm.

2. The high-temperature resistant PPS mesh for wet pulp spreading according to claim 1, characterized in that, The modified PPS resin is composed of PPS base chips, a hydrophilic melt index modifier, and an antioxidant stabilizer. The hydrophilic melt index modifier is sodium 1-naphthalenesulfonate, and its mass percentage content in the modified PPS resin is 1.5%-5.0%.

3. The high-temperature resistant PPS mesh for wet pulp spreading according to claim 1, characterized in that, The PPS monofilaments in the high-strength support skeleton layer undergo a multi-stage stretching process with a magnification ratio of 3.5 to 5.5 times before weaving; the weaving process adopts plain weave, twill weave, or multiple warp and weft weave structures, wherein the warp density is 200 threads / 10cm-500 threads / 10cm, and the weft density is 150 threads / 10cm-400 threads / 10cm.

4. The high-temperature resistant PPS mesh for wet pulp spreading according to claim 1, characterized in that, The thermophysical bonding interface is a semi-molten anchoring structure formed by the ultrafine fibers under hot rolling conditions of 265℃-275℃. The ultrafine fibers are partially embedded in the gaps between the monofilaments of the high-strength support skeleton layer and form a microscopic physical interlocking structure on the surface of the monofilaments. The interfacial bonding strength between the surface hydrophilic functional layer and the high-strength support skeleton layer is characterized by peel force.

5. The high-temperature resistant PPS mesh for wet pulp spreading according to claim 2, characterized in that, The PPS base chips are acid-washed; the modified PPS resin also includes 0.2%-0.8% by mass of a carbodiimide anti-hydrolysis agent.

6. A method for preparing a high-temperature resistant PPS mesh for wet pulp spreading as described in any one of claims 1 to 5, characterized in that, Includes the following steps: The first step is to vacuum dry the PPS base chips. Then, the dried PPS base chips are mixed with dehydrated sodium 1-naphthalenesulfonate powder and antioxidant. The material is fed into a co-rotating twin-screw extruder for melt extrusion and shearing. The extruded strips are water-cooled, air-dried and pelletized to obtain hydrophilic modified PPS masterbatch. The second step involves blending and drying hydrophilic modified PPS masterbatch and ordinary PPS chips at a mass ratio of 1:2 to 1:

5. The melt is then extruded through a spinneret using a meltblown forming system and stretched with a high-pressure hot air stream. The stretched ultrafine fibers are deposited on a receiving device to form a preliminary preform with a surface hydrophilic functional layer. The third step is to use PPS monofilaments as warp and weft threads on a heavy-duty loom, and then perform heat setting and preheating shrinkage treatment after weaving. The fourth step is to lay the initial blank of the surface hydrophilic functional layer on the surface of the high-strength support skeleton layer and send it into a multi-roll hot rolling composite machine for composite, so that the ultrafine fibers form a physical interlocking structure on the surface of the monofilament. The fifth step involves placing the composite mesh into a heat-setting box to relieve internal stress, followed by cooling, testing, and winding.

7. The method for preparing a high-temperature resistant PPS mesh for wet pulp spreading according to claim 6, characterized in that, In the first step, sodium 1-naphthalenesulfonate needs to be dried under vacuum at 100°C until the moisture content is less than 100ppm; the temperature distribution of the twin-screw extruder is set as follows: Zone 1 150-180°C, Zone 2 240-260°C, Zones 3 to 8 275-290°C, Zones 9 to 10 260-275°C, and the screw speed is 300rpm-500rpm; and the vacuum degree inside the extruder is maintained below -0.09MPa to discharge volatiles.

8. The method for preparing a high-temperature resistant PPS mesh for wet pulp spreading according to claim 6, characterized in that, In the second step, the extrusion temperature of meltblown forming is controlled at 285℃-310℃, and the micro-orifice diameter of the spinneret is 0.1mm-0.3mm; the pressure of the high-pressure hot air flow is 0.1MPa-0.4MPa, and the temperature is 300℃-330℃; the receiving distance in the meltblown process is set to 150mm-350mm.

9. The method for preparing a high-temperature resistant PPS mesh for wet pulp spreading according to claim 6, characterized in that, In the third step, the temperature of the heat setting and preheating shrinkage treatment is 220℃-240℃; before weaving, the step of plasma activation treatment on the surface of the PPS monofilament is also included.

10. The method for preparing a high-temperature resistant PPS mesh for wet pulp spreading according to claim 6, characterized in that, In the fourth step, the multi-roll hot rolling composite mill uses steel rolls with micro-pit textures paired with flat rubber rolls, the depth of which is 0.1mm-0.3mm; the hot rolling speed is controlled at 2m / min-10m / min.

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