A light and thin polytetrafluoroethylene-based cloth material and a preparation method thereof

Abstract

The present application relates to a kind of light and thin polytetrafluoroethylene base cloth material and its preparation method.The base cloth is made by film split flat yarn weaving forming, the film split flat yarn is formed by polytetrafluoroethylene, Nafion type perfluorosulfonic acid resin, polyetherimide, melamine-glycolate condensate and tri (2,2,2-trifluoroethyl) phosphate blend after melt extrusion and two-way stretching, with specific linear density, width and thickness.The base cloth adopts the double-layer structure of outer layer twill and inner layer plain, and sets up interlayer binding line to enhance structural stability.Its preparation method includes component pretreatment and blending, two-way stretching and film splitting, double-layer weaving, tension winding and heat setting and the like steps, realizes the controllability and stability of fabric in porosity, thickness and morphology.The obtained base cloth has excellent dimensional stability, delamination resistance and thermal stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polytetrafluoroethylene cloth, and particularly relates to a light and thin polytetrafluoroethylene base cloth material and a preparation method thereof. BACKGROUND

[0002] Polytetrafluoroethylene (PTFE) is widely used in industrial fabrics, filter materials, electrical insulation layers and protective equipment due to its excellent chemical inertness, high temperature resistance, electrical insulation and weather resistance. In practical applications, PTFE fabric is often used in high temperature corrosion environment as a functional material to play the role of heat insulation, protection and structural support. Traditional PTFE spinning methods mainly include paste extrusion method and dispersion emulsion spinning method. However, due to the high melting point, high melt viscosity and strong crystallinity of PTFE itself, the processing difficulty is relatively large, and problems such as fracture, uneven dispersion or insufficient strength are prone to occur when forming fiber or film crack structure.

[0003] In order to improve the processing performance of PTFE and improve its processability in fiber form, some studies propose to use a blending modification method, that is, blending PTFE with other thermoplastic polymers, and then performing bidirectional stretching after melt extrusion to form a film crack flat silk with longitudinal and transverse orientation structure. This kind of film crack flat silk can be used for woven fabric to improve the overall mechanical properties and forming stability. However, in the actual preparation process, the compatibility between the multiple components in the blending system is poor, and macroscopic phase separation phenomenon is prone to occur in the high temperature melt state, which limits the structural uniformity of the extruded sheet. In addition, in the film cracking process, different stretching ratios, stretching temperatures and cooling methods and other process parameters have a significant impact on the width, thickness and mechanical properties of the flat silk, and lack of effective control methods may lead to large fluctuations in product performance.

[0004] In terms of fabric structure design, the existing woven fabric based on PTFE film crack flat silk mostly adopts single-layer plain or twill structure, which has certain mechanical properties and flexibility, but in complex service environment, it is easy to cause structure deformation, interlayer slip or local fracture, affecting the service reliability. Some studies attempt to use multi-layer fabric structure or change the weaving path to improve the overall stability of the fabric, but due to the limited interlayer connection method, the fabric may still have problems such as peeling and delamination under stress or thermal load.

[0005] In addition, heat treatment is an indispensable step in the preparation process of film split flat yarn and base fabric, which aims to stabilize the size, release internal stress and improve the fabric morphology. However, different heat setting temperatures, treatment atmospheres and tension control parameters have great differences on the performance of the base fabric. For example, the heat setting treatment in air as usual can cause surface oxidative degradation of the material, thereby affecting the heat resistance and appearance consistency. If the heat treatment process is not precisely controlled, the fabric is prone to uneven shrinkage, warping or tension fracture, which seriously affects its processing adaptability and final use performance. SUMMARY

[0006] In view of the deficiencies in the prior art, the purpose of the present application is to provide a light and thin polytetrafluoroethylene base fabric material and a preparation method thereof.

[0007] A light and thin polytetrafluoroethylene base fabric material, which is woven into shape by film split flat yarn, the film split flat yarn is formed by melt blending extrusion and bidirectional stretching of the following components in parts by weight: 60-75 parts of polytetrafluoroethylene; 10-25 parts of perfluorosulfonic acid resin, the perfluorosulfonic acid resin is Nafion type resin; 5-15 parts of polyetherimide; 1-4 parts of melamine-glycolate condensate; 0.5-3 parts by mass of tris(2,2,2-trifluoroethyl) phosphate.

[0008] The linear density of the film split flat yarn is 80-150 dtex, the thickness is 16-24 μm, and the width is 0.20-0.28 mm.

[0009] The base fabric adopts a double-layer weaving structure, which includes: an outer layer of a twill weaving layer, the warp density is 65-75 roots / 10 cm, the weft density is 55-65 roots / 10 cm, and the unit area mass is 18-22 g / m 2 .

[0010] The inner layer is a plain weaving layer, the warp density is 50-60 roots / 10 cm, the weft density is 45-55 roots / 10 cm, and the unit area mass is 15-19 g / m 2 .

[0011] Preferably, the polytetrafluoroethylene and the perfluorosulfonic acid resin are respectively subjected to high-speed pre-dispersion treatment at a shear rate of 800-1200 rpm before blending, and the treatment time is 5-10 min.

[0012] Preferably, the melamine-glycolate condensate is added in batches during the melt blending process, the batch number is 2-4, and the interval time of each batch is 3-8 min.

[0013] Preferably, the tri(2,2,2-trifluoroethyl) phosphate is added in the blend at a linear rate, the feeding rate is 0.05-0.15 g / min, and uniform stirring is maintained at a temperature of 280-320℃ for 10-30 min.

[0014] Preferably, 1-3 binding lines formed by the film split filaments are arranged between the outer diagonal weave layer and the inner plain weave layer, the binding lines are arranged in a spiral path across the layers, and the pitch is 0.5-2.0 cm.

[0015] Preferably, the porosity of the outer weave layer is 8-12%, the porosity of the inner weave layer is 14-20%, and the total thickness of the base cloth is 180-240 μm.

[0016] Preferably, the film split filaments are subjected to ultrasonic waves with a frequency of 18-25 kHz in a cooling medium after melt extrusion, the ultrasonic wave treatment time is 5-20 s, and the cooling medium is water or a fluorinated liquid coolant.

[0017] A method for preparing a light and thin polytetrafluoroethylene base cloth material, comprising the following steps: S1: raw material blending and extrusion: melt blending and extruding the following components to form a film split sheet: 60-75 parts of polytetrafluoroethylene; 10-25 parts of perfluorosulfonic acid resin; 5-15 parts of polyetherimide; 1-4 parts of melamine-glycolate condensate; and 0.5-3 parts of tri(2,2,2-trifluoroethyl) phosphate.

[0018] S2: biaxial stretching and film splitting treatment: stretching the sheet in the longitudinal and transverse directions to a thickness of 16-24 μm, to form film split filaments with a width of 0.20-0.28 mm and a linear density of 80-150 dtex.

[0019] S3: base cloth weaving: using the film split filaments to weave a double-layered cloth, including: an outer diagonal weave layer with a warp density of 65-75 threads / 10 cm and a weft density of 55-65 threads / 10 cm; and an inner plain weave layer with a warp density of 50-60 threads / 10 cm and a weft density of 45-55 threads / 10 cm.

[0020] S4: tension winding and heat setting: using a winding device with a micro-particle ceramic roller surface during winding, controlling the tension to be 1.4-1.8 N / cm, and heat setting at 190-210℃ for 45-65 min after winding.

[0021] Preferably, during the heat setting process in step S4, the heat setting treatment is carried out in an inert atmosphere, the inert gas is nitrogen or argon, and the atmosphere flow rate is controlled to be 10-30 L / min.

[0022] Compared with the prior art, the beneficial effects of the present application mainly manifest in the following aspects: 1. By synergistic blending design of polytetrafluoroethylene, Nafion type perfluorosulfonic acid resin and polyetherimide, and combining with bidirectional stretching to form a structure uniform film split flat yarn, the base cloth still has good mechanical strength and weaving adaptability under the premise of maintaining a relatively thin thickness, and exhibits certain comprehensive advantages in lightweight and durability.

[0023] 2. Melamine-glycolate condensate and tris(2,2,2-trifluoroethyl) phosphate are introduced, and their distribution is controlled by multi-stage feeding and linear feeding mode, and the microphase separation is enhanced by ultrasonic treatment, which is helpful to build a more stable interface structure, and may play a positive role in improving the dimensional stability and chemical inertness at high temperature.

[0024] 3. The spiral combination line formed by introducing the film split flat yarn between the twill weave layer and the plain weave layer constructs a cross-layer connection path, which can inhibit the interlayer slip and warping phenomenon of the double-layer structure to a certain extent during use, thereby improving the overall form retention ability and long-term service stability of the base cloth. DETAILED DESCRIPTION

[0025] The present application will be described in detail below in conjunction with examples.

[0026] Example 1: The present example provides a preparation method of a lightweight polytetrafluoroethylene base cloth material, and the specific steps are as follows: S1: raw material blending extrusion: the raw materials are weighed according to the following ratio (by mass fraction): polytetrafluoroethylene: 67 parts; a suspension polymerization type PTFE powder with an average particle size of about 400 μm is selected, and the brand is Chemours Teflon TM PTFE 7C, the melting point is about 327℃.

[0027] Perfluorosulfonic acid resin (Nafion type): 18 parts; dry Nafion resin particles with an equivalent weight of 1100 and an ion exchange capacity of about 0.91 meq / g are selected, and the model is Nafion TM NR50 (supplied by Sigma-Aldrich), the particle size distribution is 20-80 μm, and the moisture content is <1% after drying treatment.

[0028] Polyetherimide (PEI): 10 parts; PEI resin particles with the trade name Ultem TM 1000 (provided by SABIC company), the glass transition temperature is about 217℃, and the melt index is 10 g / 10 min (measured at 337℃ / 6.6 kg).

[0029] Melamine-glycolate condensate: 2.5 parts; white low molecular weight thermally stable powder formed by condensation of melamine with glycolate in molar ratio 1 :3 under acid catalysis, solid content > 98%, particle size 10-50 μm.

[0030] Tris(2,2,2-trifluoroethyl)phosphate: 1.5 parts. A transparent liquid additive of chemical purity grade was selected, with molecular formula (CF3CH2O)3PO, CAS number 15647-14-8, and viscosity of about 30 mPa-s (25°C), purchased from Alfa Aesar.

[0031] In which: the polytetrafluoroethylene powder and the perfluorosulfonic acid resin were separately pre-dispersed in a high-speed disperser with a shear rate of 1000 rpm for 7 minutes to ensure uniform dispersion and no obvious agglomeration.

[0032] PEI and melamine-glycolate condensate were pre-mixed under heating and melting conditions to improve their compatibility with PTFE / Nafion.

[0033] The above components were sequentially added to a twin-screw extruder, with the main heating zone temperature set to 335°C (divided into four sections 310 / 325 / 335 / 345°C), and nitrogen protection throughout to prevent degradation.

[0034] During the blending process, the melamine-glycolate condensate was added in batches, with three batches each with a 5-minute interval; the tris(2,2,2-trifluoroethyl)phosphate was slowly added at a linear rate of 0.1 g / min, and the blended material was uniformly stirred at an extrusion zone temperature of 300°C for 25 minutes, and finally extruded into a film split material.

[0035] S2: biaxial stretching and split film treatment: the above material was first stretched in the longitudinal direction at a stretch ratio of 3.5, and then stretched in the transverse direction at a stretch ratio of 3.0, with the temperature controlled at 280°C during stretching, finally obtaining a film split flat yarn with a thickness of 20 μm, a width of 0.24 mm, and a linear density of 106 dtex.

[0036] To improve the uniformity of the internal microvoids and mechanical strength of the flat yarn structure, after the stretching was completed, the flat yarn passed through a cooling tank containing a fluorinated liquid coolant (trade name Fluorinert FC-770), and a ultrasonic source with a frequency of 22 kHz and a power of 120 W was introduced into the liquid, with an ultrasonic action time of 12 seconds.

[0037] S3: Base fabric weaving: Take the film split filament as the warp and weft material, and weave using a double-layer structure: outer layer twill weave layer: warp density: 70 roots / 10 cm; weft density: 60 roots / 10 cm; unit area mass: 20 g / m2; fabric porosity is controlled at 10% (controlled by warp and weft tightness and organizational structure).

[0038] Inner layer plain weave layer: warp density: 55 roots / 10 cm; weft density: 50 roots / 10 cm; unit area mass: 17 g / m2; fabric porosity is controlled at 17%.

[0039] In order to improve the bonding strength and interface stability of the double-layer structure, two film split filaments are introduced as bonding lines during weaving, and the bonding lines are arranged in a spiral path with a pitch of 1.0 cm.

[0040] S4: Tension winding and heat setting: The woven double-layer base fabric is wound by a winding device, and the surface of the winding device is covered with a ceramic particle spray layer to increase the friction and prevent slipping.

[0041] During winding: the tension is controlled at 1.6 N / cm; the winding rate is set at 12 m / min.

[0042] Subsequently, the wound base fabric is placed in a heat setting oven for heat setting treatment at a temperature of 200℃ for 60 minutes. During the setting process, a nitrogen protective atmosphere is maintained, and the gas flow rate is set at 20 L / min to prevent thermal oxidative aging.

[0043] Example 2: This example provides a preparation method of a light and thin polytetrafluoroethylene base fabric material, and the specific steps are as follows: S1: raw material blending extrusion: the raw materials are weighed according to the following ratio (by mass fraction): polytetrafluoroethylene: 72 parts; select a suspension polymerization type PTFE powder with an average particle size of about 400 μm, brand: Chemours Teflon TM PTFE 7C, melting point about 327℃.

[0044] Perfluorosulfonic acid resin (Nafion type): 15 parts; select dry Nafion resin particles with an equivalent weight of 1100 and an ion exchange capacity of about 0.91 meq / g, model: Nafion TM NR50 (supplied by Sigma-Aldrich), particle size distribution of 20-80 μm, dried to a moisture content of <1%.

[0045] Polyetherimide (PEI): 6 parts; select PEI resin particles with trade name Ultem TM 1000 (provided by SABIC company), glass transition temperature about 217℃, melt index 10 g / 10 min (measured at 337℃ / 6.6 kg).

[0046] Melamine-glycolate condensate: 3 parts; white low molecular weight thermally stable powder formed by condensation of melamine with glycolate in molar ratio 1 :3 under acid catalysis, solid content > 98%, particle size 10-50 pm.

[0047] Tris(2,2,2-trifluoroethyl)phosphate: 2 parts. A transparent liquid additive of chemical purity grade with molecular formula (CF3CH20)3PO and CAS number 15647-14-8 was selected, having a viscosity of about 30 mPa-s (25°C) and purchased from Alfa Aesar.

[0048] wherein: the polytetrafluoroethylene powder and the perfluorosulfonic acid resin were separately pre-dispersed in a high-speed disperser with a shear rate of 1000 rpm for 7 minutes to ensure uniform dispersion without significant agglomeration.

[0049] PEI was pre-mixed with melamine-glycolate condensate under heat and melt conditions to improve its compatibility with PTFE / Nafion.

[0050] The above components were sequentially added to a twin-screw extruder, with the main heating zone temperature set to 335°C (divided into four sections 310 / 325 / 335 / 345°C), and nitrogen was used for protection throughout the process to prevent degradation.

[0051] During the blending process, the melamine-glycolate condensate was added in batches, with three batches and a 6-minute interval between each batch; the tris(2,2,2-trifluoroethyl)phosphate was slowly added at a linear rate of 0.12 g / min, and the blending material was processed in the 310-340°C section, with a total heat residence time < 5 min, and finally extruded into a film split material.

[0052] S2: biaxial stretching and split film processing: the above material was first stretched in the longitudinal direction at a stretching ratio of 3.8 times, and then stretched in the transverse direction at a stretching ratio of 3.2 times, with the temperature controlled at 270°C during the stretching process, finally obtaining a film split flat yarn with a thickness of 18 pm, a width of 0.22 mm, and a linear density of 87 dtex.

[0053] To improve the uniformity of the internal microvoids and mechanical strength of the flat yarn structure, after the stretching was completed, the flat yarn passed through a cooling tank containing a fluorinated liquid coolant (trade name Fluorinert FC-770), and a ultrasonic source with a frequency of 22 kHz and a power of 120 W was introduced into the liquid, with an ultrasonic action time of 12 seconds.

[0054] S3: Base fabric weaving: The film split filament is used as the warp and weft material, and a double-layer structure is woven: outer layer twill weave layer: warp density: 68 strands / 10 cm; weft density: 58 strands / 10 cm; unit area mass: 19 g / m2; fabric porosity is controlled at 11% (controlled by warp and weft tightness and organizational structure).

[0055] Inner layer plain weave layer: warp density: 52 strands / 10 cm; weft density: 48 strands / 10 cm; unit area mass: 16 g / m2; fabric porosity is controlled at 15%.

[0056] In order to improve the bonding strength and interface stability of the double-layer structure, two film split filaments are introduced as bonding lines during weaving, and the bonding lines are arranged in a spiral path with a pitch of 1.5 cm.

[0057] S4: Tension winding and heat setting: The woven double-layer base fabric is wound by a winding device, and the surface of the winding device is covered with a ceramic particle spray layer to increase the friction and prevent slipping.

[0058] During winding: the tension is controlled at 1.5 N / cm; the winding rate is set at 10 m / min.

[0059] Then the wound base fabric is placed in a heat setting oven for heat setting treatment at a temperature of 195℃ for 50 minutes. During the setting process, a nitrogen protective atmosphere is maintained, and the gas flow rate is set at 15 L / min to prevent thermal oxidative aging.

[0060] Example 3: This example provides a preparation method of a light and thin polytetrafluoroethylene base fabric material, and the specific steps are as follows: S1: raw material blending extrusion: the raw materials are weighed according to the following ratio (by mass fraction): polytetrafluoroethylene: 62 parts; a suspension polymerization type PTFE powder with an average particle size of about 400 μm is selected, and the brand is Chemours Teflon TM PTFE 7C, melting point about 327℃.

[0061] Perfluorosulfonic acid resin (Nafion type): 22 parts; dry Nafion resin particles with an equivalent weight of 1100 and an ion exchange capacity of about 0.91 meq / g are selected, and the model is Nafion TM NR50 (supplied by Sigma-Aldrich), particle size distribution is 20-80 μm, and the moisture content is <1% after drying treatment.

[0062] Polyetherimide (PEI): 14 parts; PEI resin particles with trade name Ultem TM 1000 (provided by SABIC company), glass transition temperature about 217℃, melt index 10 g / 10 min (measured at 337℃ / 6.6 kg).

[0063] Melamine-glycolate condensate: 1.2 parts; white low molecular weight thermally stable powder formed by condensation of melamine with glycolate in molar ratio 1 :3 under acid catalysis, solid content > 98%, particle size 10-50 μιη.

[0064] Tris(2,2,2-trifluoroethyl)phosphate: 0.8 parts. A transparent liquid additive of chemical purity grade with molecular formula (CF3CH20)3PO, CAS number 15647-14-8, and viscosity of about 30 mPa-s (25 °C) was purchased from Alfa Aesar.

[0065] Wherein: the polytetrafluoroethylene powder and the perfluorosulfonic acid resin were separately placed in a high-speed disperser with a shear rate of 1200 rpm for pre-dispersion treatment, and the treatment time was 10 minutes to ensure that the two were uniformly dispersed without obvious agglomeration.

[0066] The PEI and the melamine-glycolate condensate were premixed under heating and melting conditions to improve their compatibility with the PTFE / Nafion.

[0067] The above components were sequentially added to a twin-screw extruder, and the temperature of the main heating zone was set to 335 °C (divided into four sections 310 / 325 / 335 / 345 °C), and nitrogen was used for protection throughout the process to prevent degradation.

[0068] During the blending process, the melamine-glycolate condensate was added in batches, and each batch was separated by 8 minutes; the tris(2,2,2-trifluoroethyl)phosphate was slowly added at a linear rate of 0.08 g / min, and the blended material was uniformly stirred at an extrusion zone temperature of 300 °C for 20 minutes, and finally extruded to form a film split material.

[0069] S2: biaxial stretching and film splitting treatment: the above material was first stretched in the longitudinal direction at a stretching ratio of 3.0, and then stretched in the transverse direction at a stretching ratio of 2.8, and the temperature during stretching was controlled at 260 °C, and finally a film split flat yarn with a thickness of 24 μιη and a width of 0.28 mm was obtained.

[0070] To improve the uniformity of the internal microvoids and the mechanical strength of the flat yarn structure, after the stretching was completed, the flat yarn passed through a cooling tank containing a fluorinated liquid coolant (trade name Fluorinert FC-770), and a ultrasonic source with a frequency of 22 kHz and a power of 120 W was introduced into the liquid, and the ultrasonic action time was 12 seconds.

[0071] S3: Woven fabric: The film split filament is used as the warp and weft material, and a double-layer structure is woven: the outer layer is a twill weave layer: warp density: 75 strands / 10 cm; weft density: 65 strands / 10 cm; unit area mass: 22 g / m2; the fabric porosity is controlled at 9% (controlled by the tightness and structure of the warp and weft).

[0072] The inner layer is a plain weave layer: warp density: 60 strands / 10 cm; weft density: 55 strands / 10 cm; unit area mass: 19 g / m2; the fabric porosity is controlled at 20%.

[0073] To improve the bonding strength and interface stability of the double-layer structure, two film split filaments are introduced as bonding lines during weaving, and the bonding lines are arranged in a spiral path with a pitch of 0.5 cm.

[0074] S4: Tension winding and heat setting: The woven double-layer fabric is wound by a winding device, and the surface of the winding device is covered with a ceramic particle spray layer to increase the friction and prevent slipping.

[0075] During winding: the tension is controlled at 1.8 N / cm; the winding speed is set at 15 m / min.

[0076] Then the wound fabric is placed in a heat setting oven for heat setting treatment at a temperature of 210°C for 65 minutes. During the setting process, a nitrogen protective atmosphere is maintained, and the gas flow rate is set at 30 L / min to prevent thermal oxidative aging.

[0077] Comparative Example 1: This comparative example discloses a method for preparing a fabric material, comprising the following steps: S1: raw material blending extrusion: the raw materials are weighed according to the following ratio (by mass parts): polytetrafluoroethylene: 85 parts; a suspension polymerization type PTFE powder with an average particle size of about 400 μm is selected, the brand is Chemours Teflon TM PTFE 7C, melting point about 327°C.

[0078] Polyetherimide (PEI): 10 parts; model Ultem TM 1000 (provided by SABIC), glass transition temperature about 217°C.

[0079] Melamine-glycolate condensate: 3 parts; a melamine-glycolate condensate powder with a solid content of ≥98% and a particle size of 10-50 μm.

[0080] Tris (2, 2, 2-trifluoroethyl) phosphate: 2 parts; a transparent liquid additive, CAS No. 15647-14-8, viscosity 30 mPa·s, purchased from Alfa Aesar.

[0081] The mixing process is as follows: PTFE and PEI are pre-dispersed at 1000 rpm high shear for 7 minutes, respectively.

[0082] PEI and melamine condensate are pre-mixed in a molten state (180°C).

[0083] All components are added to a twin-screw extruder, and the temperature of the main heating zone is set to 335°C (in four sections: 310 / 325 / 335 / 345°C), with nitrogen protection.

[0084] Melamine-glycolate condensate is added in three batches, with an interval of 5 minutes between each batch.

[0085] Tris(2,2,2-trifluoroethyl)phosphate is added dropwise at a linear rate of 0.1 g / min.

[0086] Keep stirring evenly for 25 minutes, and extrude into a sheet.

[0087] S2: Biaxial stretching and film splitting treatment: first stretch the film sheet longitudinally (3.5x), then stretch it transversely (3.0x), with temperature control at 270°C; the final film split filament thickness is 20μm, and the width is 0.24mm; after stretching, introduce 22kHz ultrasonic wave treatment in a Fluorinert FC-770 cooling tank for 12 seconds, with power of 120W.

[0088] S3: Base fabric weaving: use the above film split filament for double-layer weaving: outer diagonal woven layer: warp density: 70 strands / 10cm; weft density: 60 strands / 10cm; unit area mass: 20g / m 2 ; porosity is 10%.

[0089] Inner plain woven layer: warp density: 55 strands / 10cm; weft density: 50 strands / 10cm; unit area mass: 17g / m 2 ; porosity is 17%; use 2 film split filament binding threads, with a pitch of 1.0cm, and spiral cross-layer arrangement.

[0090] S4: Tension winding and heat setting: the winding device is a ceramic particle roller surface, with tension set to 1.6N / cm, and winding rate of 12m / min; use infrared edge detection and lever mechanism for coordinated control of the fabric edge; heat setting is carried out at 200°C for 60 minutes, using nitrogen atmosphere, with flow rate of 20L / min.

[0091] Comparative Example 2: This comparative example discloses a method for preparing a base fabric material, including the following steps: S1: raw material blending extrusion: weigh the raw materials (in mass parts) according to the following ratio: polytetrafluoroethylene: 67 parts.

[0092] Perfluorosulfonic acid resin: 18 parts.

[0093] Polyetherimide: 10 parts.

[0094] Melamine-glycolate condensate: 2.5 parts.

[0095] Tris(2,2,2-trifluoroethyl)phosphate: 1.5 parts.

[0096] The materials are selected in accordance with Example 1. The processing procedure is as follows: PTFE and Nafion are pre-dispersed at 1000 rpm for 7 minutes.

[0097] PEI and melamine condensate are pre-mixed in a molten state.

[0098] All components are sequentially added to a twin-screw extruder, and the temperature of the main heating zone is set to 300°C under nitrogen protection.

[0099] The difference from the example is that the melamine-glycolate condensate is added all at once at the beginning of blending, and the batch method is not used.

[0100] Tris(2,2,2-trifluoroethyl)phosphate is still added at a linear rate of 0.1 g / min.

[0101] Stirring is maintained for 25 minutes, and extrusion is performed to form a sheet.

[0102] S2-S4 are the same as Example 1.

[0103] Comparative Example 3: This comparative example discloses a preparation method of a base fabric material, comprising the following steps: S1: raw material blending and extrusion: the raw materials (in mass parts) are weighed according to the following ratio: polytetrafluoroethylene: 67 parts.

[0104] Perfluorosulfonic acid resin: 18 parts.

[0105] Polyetherimide: 10 parts.

[0106] Melamine-glycolate condensate: 2.5 parts.

[0107] Tris(2,2,2-trifluoroethyl)phosphate: 1.5 parts.

[0108] The raw materials are selected in accordance with Example 1, and the processing procedure is as follows: PTFE and Nafion are pre-dispersed at 1000 rpm for 7 minutes.

[0109] PEI and melamine condensate are pre-mixed in a molten state at 180°C.

[0110] All the above components are sequentially added to a twin-screw extruder, and the temperature of the main heating zone is set to 300°C under nitrogen protection.

[0111] The differences between the example and the present application are as follows: the melamine-glycolate condensate is added in three batches, with an interval of 5 minutes between each batch; the tris (2, 2, 2-trifluoroethyl) phosphate is added all at once at the beginning of the feeding, and after mixing for 10 minutes, it is directly fed into the extrusion stage.

[0112] This method is prone to cause local excessive enrichment or migration of low-volatility phosphates at high temperatures, affecting the stability of the final structure.

[0113] The final blended system is extruded after blending at a temperature of 300°C for 10 minutes to form a film.

[0114] S2-S4: The subsequent processing procedures are consistent with Example 1.

[0115] Comparative Example 4: This comparative example discloses a method for preparing a base fabric material, including the following steps: S1 and S2 are the same as the operation of the example.

[0116] S3: Base fabric weaving (difference): The difference between the present application and the example is that no film split flat filament binding line is set, as follows: outer layer twill weave layer: warp density: 70 ends / 10 cm; weft density: 60 ends / 10 cm; unit area mass: 20 g / m²; porosity: 10%.

[0117] Inner layer plain weave layer: warp density: 55 ends / 10 cm; weft density: 50 ends / 10 cm; unit area mass: 17 g / m²; porosity: 17%; the film split flat filament binding line structure design is cancelled, and no cross-layer structure connection is performed during weaving, only relying on the weaving density to form a sandwich fit.

[0118] S4 is consistent with Example 1.

[0119] Performance testing: 1. Tensile strength test method.

[0120] Method: Cut samples with a width of 5 cm and a length of 30 cm; use a universal material testing machine; the tensile speed is 100 mm / min, and the maximum breaking load is recorded; test 5 groups in the warp and weft directions, and take the average value.

[0121] 2. High temperature dimensional change rate test method.

[0122] Method: Cut 10 cm x 10 cm samples; place in a 200°C air drying oven for 30 minutes; measure the length and width after natural cooling; dimensional change rate = |pre-treatment size - post-treatment size| / original size x 100%.

[0123] 3. Oxygen index (LOI) test method.

[0124] Method: Refer to GB / T2406.2-2009 standard.

[0125] Using an oxygen index tester; cutting a sample with a size of 120 mm x 10 mm x thickness; igniting in a prescribed oxygen / nitrogen mixed gas stream, and recording the minimum oxygen concentration required to maintain combustion.

[0126] 4. Heat shrinkage test method (200°C).

[0127] Method: cut a sample 10 cm long; again placed in a 200°C environment for 15 minutes; after cooling, measure the length change; heat shrinkage = (original length - length after heating) / original length x 100%.

[0128] The test results are shown in Table 1 below.

[0129] Table 1:

[0130] The above only describes the preferred embodiments of the present application, and the protection scope of the present application is not limited to the above-described embodiments only, and any technical solutions falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the present application shall also be considered as the protection scope of the present application.

Claims

1. A lightweight polytetrafluoroethylene (PTFE) vinyl fabric material, characterized in that, The base fabric is woven from split-sheet flat yarns, which are formed by melt blending, extrusion, and biaxial stretching of the following components in parts by weight: 60-75 parts polytetrafluoroethylene; 10-25 parts perfluorosulfonic acid resin, wherein the perfluorosulfonic acid resin is a Nafion type resin; 5-15 parts polyetherimide; 1-4 parts melamine-glycolate condensate; and 0.5-3 parts by weight of tris(2,2,2-trifluoroethyl) phosphate. The linear density of the split-sheet flat yarns is 80-150 dtex, the thickness is 16-24 μm, and the width is 0.20-0.28 mm. The base fabric adopts a double-layer woven structure, including: an outer twill weave layer with a warp density of 65-75 threads / 10cm, a weft density of 55-65 threads / 10cm, and a unit area mass of 18-22 g / m². 2 The inner layer is a plain weave, with a warp density of 50–60 threads / 10cm and a weft density of 45–55 threads / 10cm, and a unit area mass of 15–19 g / m². 2 .

2. The lightweight polytetrafluoroethylene vinyl fabric material according to claim 1, characterized in that, The polytetrafluoroethylene and perfluorosulfonic acid resin are subjected to high-speed pre-dispersion treatment at a shear rate of 800-1200 rpm before blending, and the treatment time is 5-10 min.

3. The lightweight polytetrafluoroethylene vinyl fabric material according to claim 2, characterized in that, The melamine-glycolate condensate is added in batches during the melt blending process, with 2 to 4 batches and an interval of 3 to 8 minutes between each batch.

4. The lightweight polytetrafluoroethylene vinyl fabric material according to claim 3, characterized in that, The tris(2,2,2-trifluoroethyl) phosphate ester is added to the blend at a linear rate of 0.05–0.15 g / min, and is stirred uniformly at a temperature of 280–320 °C for 10–30 min.

5. The lightweight polytetrafluoroethylene vinyl fabric material according to claim 4, characterized in that, One to three bonding lines formed by membrane-split flat filaments are provided between the outer twill weave layer and the inner plain weave layer. The bonding lines are arranged across layers in a spiral path with a pitch of 0.5 to 2.0 cm.

6. The lightweight polytetrafluoroethylene vinyl fabric material according to claim 1, characterized in that, The outer layer has a porosity of 8–12%, the inner layer has a porosity of 14–20%, and the total thickness of the base fabric is 180–240 μm.

7. The lightweight polytetrafluoroethylene vinyl fabric material according to claim 6, characterized in that, After melt extrusion, the membrane-split flat filament is transmitted with ultrasonic waves at a frequency of 18-25 kHz through a cooling medium. The ultrasonic wave action time is 5-20 seconds, and the cooling medium is water or fluorinated liquid coolant.

8. A method for preparing a thin polytetrafluoroethylene vinyl fabric material according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1: Raw material co-extrusion: The following components are melt-blended and extruded to form a film-splitting sheet: 60-75 parts of polytetrafluoroethylene; 10-25 parts of perfluorosulfonic acid resin; 5-15 parts of polyetherimide; 1-4 parts of melamine-glycolate condensate; 0.5-3 parts of tris(2,2,2-trifluoroethyl) phosphate; S2: Biaxial stretching and film splitting treatment: The sheet is stretched longitudinally and transversely to a thickness of 16-24 μm to form a film-splitting flat filament with a width of 0.20-0.28 mm and a linear density of 80-150 dtex; S3: Base fabric weaving: Double-layer weaving is carried out using the aforementioned split flat yarn, including: an outer layer of twill weave with a warp density of 65-75 threads / 10cm and a weft density of 55-65 threads / 10cm; and an inner layer of plain weave with a warp density of 50-60 threads / 10cm and a weft density of 45-55 threads / 10cm; S4: Tension winding and heat setting: During the winding process, a winding device with a micro-particle ceramic roller surface is used to control the tension at 1.4-1.8 N / cm. After winding, the fabric is heat-set at 190-210℃ for 45-65 minutes.

9. The method for preparing a thin and lightweight polytetrafluoroethylene vinyl fabric according to claim 8, characterized in that, In the heat setting process of step S4, the heat setting treatment is carried out in an inert atmosphere, wherein the inert gas is nitrogen or argon, and the atmosphere flow rate is controlled at 10-30 L / min.

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