Antioxidant and wear-resistant support fabric based on modified PP and its preparation process

Abstract

This invention relates to the field of polymer materials, specifically an antioxidant and wear-resistant support fabric based on modified PP and its preparation process. The fabric includes a PP fiber matrix and a core-shell bifunctional modifier uniformly dispersed in the PP fiber matrix. The core-shell bifunctional modifier has a core-shell-shell sandwich structure, sequentially comprising a core, an inner shell covering the surface of the core, and an outer shell covering the surface of the inner shell. The core is a polymeric hindered amine light stabilizer polymer segment. The inner shell is a coupling transition layer composed of the hydrolysis and condensation product of γ-methacryloyloxypropyltrimethoxysilane. The outer shell is a nano-wear-resistant ceramic shell. The total particle size of the core-shell bifunctional modifier is 50-200 nm, and its mass fraction in the PP fiber matrix is ​​3-5 wt%. This invention solves the technical problems of easy migration of antioxidants, uneven dispersion of wear-resistant fillers, and phase separation caused by the compounding of the two in traditional technologies, achieving enhanced antioxidant and wear-resistant properties.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, specifically to an antioxidant and wear-resistant support fabric based on modified PP and its preparation process. Background Technology

[0002] Polypropylene (PP) is widely used in filtration, geotechnical engineering, building materials, and industrial linings due to its advantages such as readily available raw materials, excellent processability, balanced mechanical properties, chemical resistance, and low cost. However, under harsh service environments such as outdoor conditions, high temperatures, and high friction, PP support fabrics are prone to simultaneous thermo-oxidative aging and wear failure, leading to rapid degradation of mechanical properties, structural damage, and a significantly shortened service life, making it difficult to meet the requirements of long-term, high-reliability applications.

[0003] CN116043414B discloses a wear-resistant nonwoven fabric and its production process. The wear-resistant nonwoven fabric of this application comprises the following raw materials in parts by weight: 40-80 parts modified polypropylene, 20-30 parts graphene oxide-grafted sisal fiber, 6-9 parts antioxidant, 3-7 parts plasticizer, and 1-5 parts binder. The above formula is simple and the proportions are precise, resulting in a nonwoven fabric with significant wear resistance and tensile properties. The production process of the wear-resistant nonwoven fabric of this application involves mixing modified polypropylene, antioxidant, plasticizer, and binder, followed by melt spinning to obtain composite fibers; the composite fibers are then carded with graphene oxide-grafted sisal fibers and laid into a web, subsequently needle-punched, hot-rolled, wound, and dried to obtain the wear-resistant nonwoven fabric. The above production process is simple, low-cost, and suitable for industrial production. However, antioxidants are small molecule systems that are prone to migration and volatilization during high-temperature processing and long-term use, resulting in poor long-term antioxidant performance. Graphene oxide and inorganic fillers are prone to agglomeration, resulting in insufficient dispersion uniformity and stress concentration. The technical problems of antioxidant migration and filler dispersion cannot be solved, making it difficult to simultaneously and effectively improve wear resistance and antioxidant performance.

[0004] CN116622159A discloses a polypropylene composition, its preparation method, and its application. The polypropylene composition, by weight, comprises the following components: 90-95 parts polypropylene; 1-2 parts hypophosphite; 0.5-2 parts brominated flame retardant; 0.2-0.5 parts flame retardant synergist; 0.1-0.4 parts primary antioxidant; 0.1-0.4 parts secondary antioxidant; and 0.2-0.4 parts hindered amine light stabilizer (excluding N-substituted alkoxy hindered amines). The flame retardant synergist is one or more of N-substituted alkoxy hindered amines. The polypropylene composition provided by this prior art has advantages such as resistance to high-temperature failure, long powdering time, and minimal discoloration during processing. However, it is still a simple physical blending system. The hindered amine has poor compatibility with the PP matrix, and the migration and precipitation problems are prominent. The wear-resistant nanoparticles have high surface energy and are prone to forming large-sized agglomerates, resulting in limited dispersion effect. The antioxidant and wear-resistant filler have no interfacial bond, and the complex phases are obviously separated, which cannot achieve the enhancement of antioxidant and wear-resistant properties, and can easily cause processing problems such as spinning breakage and spinneret blockage.

[0005] CN102558428B discloses a hindered amine light stabilizer with toughening effect and its preparation method. It consists of a rubbery soft core with a glass transition temperature ≤0℃ and an outer glassy hard shell with a glass transition temperature ≥60℃. Its initial thermal decomposition temperature is ≥240℃. By weight, the rubbery soft core is formed by emulsion polymerization of 100 parts of a first monomer and 1-5 parts of a crosslinking agent, while the glassy hard shell is formed by emulsion polymerization of 40-80 parts of a second monomer and 40-80 parts of a polymerizable hindered amine. This prior art introduces the hindered amine light stabilizer into the shell layer of elastomeric particles with a core-shell structure. This not only achieves high molecular weight of the hindered amine light stabilizer in a novel way, enabling long-lasting and effective light stabilization, but also provides toughening to the polymer substrate through the encapsulated rubbery soft core, offering a new bifunctional modifier for polymer substrate modification.

[0006] In summary, existing technologies struggle to produce modified PP support fabrics that combine long-lasting antioxidant properties, high wear resistance, mechanical stability, and excellent process adaptability. Therefore, developing antioxidant and wear-resistant support fabrics based on modified PP and their preparation processes has become a pressing technical challenge in this field. Summary of the Invention

[0007] To address the shortcomings of the existing technologies, an antioxidant and wear-resistant support fabric based on modified PP and its preparation process are provided. This solves the technical problems of easy migration of antioxidants, uneven dispersion of wear-resistant fillers, and phase separation caused by the compounding of the two in traditional technologies, thereby achieving enhanced antioxidant and wear-resistant properties.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is an antioxidant and wear-resistant support fabric based on modified PP, comprising a PP fiber matrix and a core-shell bifunctional modifier uniformly dispersed in the PP fiber matrix; the core-shell bifunctional modifier has a core-shell-shell sandwich structure, comprising a core, an inner shell covering the surface of the core, and an outer shell covering the surface of the inner shell; the core is a polymeric hindered amine light stabilizer polymer segment; the inner shell is a coupling transition layer composed of γ-methacryloyloxypropyltrimethoxysilane hydrolysis condensation product; the outer shell is a nano-wear-resistant ceramic shell layer; the total particle size of the core-shell bifunctional modifier is 50-200 nm, and the mass fraction in the PP fiber matrix is ​​3-5 wt%.

[0009] The aforementioned modified PP-based antioxidant and wear-resistant support fabric has a core particle size of 30-80 nm and a weight-average molecular weight of 3000-8000. The polymerizable hindered amine light stabilizer is selected from the polymerized product of bis(2,2,6,6-tetramethyl-4-piperidine) sebacate or the condensation product of 2,2,6,6-tetramethyl-4-piperidine alcohol and a diacid. The inner shell thickness is 5-15 nm.

[0010] The aforementioned antioxidant and wear-resistant support fabric based on modified PP has a nano-wear-resistant ceramic shell layer with a thickness of 15-50 nm, composed of nano-Al2O3@SiO2 composite particles or nano-SiC dispersions; the nanoparticles have a particle size of 10-50 nm and a specific surface area of ​​50-200 m². 2 / g, Mohs hardness ≥9.

[0011] The aforementioned antioxidant and wear-resistant support fabric based on modified PP has a PP fiber matrix melt index of 20-35 g / 10 min, a support fabric surface density of 80-300 g / m², and a thickness of 1-10 mm. The support fabric surface is provided with an embossed structure with a depth of 0.1-0.5 mm.

[0012] The above-mentioned preparation process of the antioxidant and wear-resistant support fabric based on modified PP includes the following steps:

[0013] S1. Preparation of W / O type reverse microemulsion;

[0014] S2. In-situ polymerization to prepare core-shell bifunctional modifier powder;

[0015] S3. Melt extrusion preparation of functional masterbatch;

[0016] S4. After blending and dilution, the support fabric is obtained by melt spinning, needle punching reinforcement, and hot rolling.

[0017] The above-mentioned preparation process of the antioxidant and wear-resistant support fabric based on modified PP is characterized in that, in step S1, the oil phase contains a surfactant compounded with Span-80 and Tween-80, with a mass ratio of 4:6 to 6:4 and a composite HLB value of 4.5-5.5; the surfactant accounts for 15-25 wt% of the oil phase mass, and the aqueous phase accounts for 10-20 wt% of the total mass of the microemulsion; the aqueous phase contains 30-50 wt% HALS monomer and 0.5-1.0 wt% potassium persulfate initiator; the microemulsion conditions are: stirring speed 10000-15000 rpm, ultrasonic power 200-400 W, ultrasonic time 10-20 min, aqueous phase droplet speed 0.5 mL / min, and microemulsion droplet size 10-50 nm.

[0018] In the above-mentioned preparation process of the antioxidant and wear-resistant support fabric based on modified PP, in step S2, the polymerization temperature is 70-80℃, the reaction is carried out under nitrogen protection and stirring at 300-500rpm for 4-6h, and the HALS monomer conversion rate is >95%; ethanol is used for demulsification, centrifugation at 8000rpm for 10min is performed, ethanol and deionized water are washed sequentially, and vacuum drying at 60℃ for 24h is performed to obtain the modifier powder.

[0019] In the above-mentioned preparation process of the antioxidant and wear-resistant support fabric based on modified PP, in step S3, the mass ratio of modifier powder to PP powder is 15-25:100, and they are mixed at 1000-1500 rpm for 3-5 min; the length-to-diameter ratio of the twin-screw extruder is ≥48:1, the screw adopts an alternating arrangement of kneading blocks and reverse conveying elements, the extrusion temperature is 180-220℃, and the screw speed is 300-400 rpm; the resulting masterbatch has a modifier content of 15-25 wt% and a melt index of 8-15 g / 10 min.

[0020] In the above-mentioned preparation process of the antioxidant and wear-resistant support fabric based on modified PP, in step S4, the mass ratio of functional masterbatch to raw PP chips is 1:4 to 1:6; the melt spinning temperature is 240-260℃, the spinneret orifice diameter is 0.3-0.5mm, the spinning speed is 800-1500m / min, the draw ratio is 2.5-3.5, the fiber fineness is 1.5-6dex, and the needle punching density is 30-80 needles / cm. 2 The needle type is 15×18×32×3, the needle punching frequency is 600-800 times / min; the hot rolling temperature is 130-150℃, and the linear pressure is 5-20kN / m.

[0021] The above-mentioned preparation process of the antioxidant and wear-resistant support cloth based on modified PP also includes low-temperature plasma surface treatment of the support cloth. The low-temperature plasma treatment uses a mixture of oxygen and argon in a ratio of 1:1 to 1:3, with a treatment power of 500-800W and a treatment time of 30-60s, in order to improve the surface wettability and coating adhesion of the support cloth.

[0022] The beneficial effects of this invention, based on modified PP antioxidant and wear-resistant support fabric and its preparation process, are that a core-shell sandwich structure bifunctional modifier is precisely constructed at the nanoscale through reverse microemulsion polymerization. The polymerizable hindered amine light stabilizer is encapsulated in a nano-wear-resistant ceramic shell, and the chemical bonding between the core and the shell is achieved through a coupling transition layer. This effectively solves the technical problems of easy migration and precipitation of antioxidants, uneven dispersion of wear-resistant fillers, and phase separation caused by the compounding of the two in traditional technologies, thereby achieving enhanced antioxidant and wear-resistant properties.

[0023] The core-shell structure encapsulates a high molecular weight hindered amine light stabilizer within a polymer shell, with a coupling agent layer providing chemical bonding, effectively preventing the hindered amine molecules from migrating to the material surface and precipitating into the external medium. Traditional small molecule antioxidants exhibit significant migration under specific conditions, while the core-shell modifier of this invention shows extremely low migration, resulting in significantly improved anti-migration stability.

[0024] The nano-ceramic shell forms a uniform hard protective layer on the fiber surface, which can effectively resist the micro-cutting of abrasive particles, and the high dispersion avoids stress concentration; the wear resistance of the support cloth of the present invention is greatly improved, and the wear resistance enhancement effect is significant.

[0025] The hindered amine core continuously releases stable free radicals into the PP matrix through a permeation diffusion mechanism, achieving real-time capture of oxidative free radicals. The reaction site density of the polymeric hindered amine light stabilizer is higher than that of small molecule antioxidants. The antioxidant induction period of traditional PP support fabric is limited, while the antioxidant induction period of the support fabric of this invention is significantly extended, and the long-term antioxidant effect is significantly improved.

[0026] The reverse microemulsion polymerization method enables the precise assembly of functional agents at the nanoscale, and the twin-screw high-shear dispersion in the preparation of masterbatch ensures the uniform distribution of functional agents in the final product. The functional agent agglomerates of the traditional blending method are large in size, while the functional agent agglomerates of the present invention are significantly reduced in size and the dispersion uniformity is significantly improved.

[0027] The functional masterbatch of the present invention is directly compatible with conventional PP spinning processes without requiring major modifications to existing equipment. It is applicable to various PP nonwoven fabric production processes such as melt spinning, meltblowing, and spunbonding, exhibiting good process compatibility and facilitating industrial promotion. Attached Figure Description

[0028] Figure 1 This is a flowchart of the preparation process of the present invention. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0030] Example 1

[0031] This embodiment relates to an antioxidant and wear-resistant support fabric based on modified PP and its preparation process. The core of this process lies in constructing a core-shell-shell sandwich structure bifunctional modifier at the nanoscale using reverse microemulsion polymerization, and uniformly dispersing this modifier within a PP fiber matrix, thereby achieving synergistic enhancement of antioxidant and wear-resistant properties. The support fabric's structure comprises a PP fiber matrix and a core-shell bifunctional modifier uniformly dispersed within it. The core-shell bifunctional modifier sequentially comprises three structural layers: a core, an inner shell, and an outer shell, forming a complete core-shell-shell sandwich structure. The core is a polymeric hindered amine light stabilizer polymer segment with a particle size controlled within the range of 30-80 nm and a weight-average molecular weight (Mw) of 3000-8000. Specifically, it can be a polymer of bis(2,2,6,6-tetramethyl-4-piperidin) sebacate (such as Tinuvin 622, GA-80) or a condensation product of 2,2,6,6-tetramethyl-4-piperidinol and a diacid. The inner shell is a coupling transition layer covering the surface of the core, with a thickness controlled in the range of 5-15 nm, and is composed of a hydrolytic condensation polymer of γ-methacryloyloxypropyltrimethoxysilane (KH-570). The outer shell is a nano-wear-resistant ceramic shell layer covering the surface of the inner shell, with a thickness controlled in the range of 15-50 nm, and is composed of nano-Al2O3@SiO2 composite particles or nano-SiC dispersions, wherein the particle size of the nano-Al2O3 particles or nano-SiC particles is 10-50 nm and the specific surface area is 50-200 m². 2 / g, with a Mohs hardness of not less than 9. The total particle size of the core-shell bifunctional modifier is controlled within the range of 50-200nm, and its mass fraction in the PP fiber matrix is ​​3-5wt%.

[0032] This embodiment also relates to the preparation process of the antioxidant and wear-resistant PP support fabric, including four main steps: preparation of reverse microemulsion, in-situ polymerization of core-shell bifunctional modifier, preparation of functional masterbatch, and preparation of PP support fabric. Each step is described in detail below.

[0033] Step S1 is the preparation of the reverse microemulsion, which includes three sub-steps: oil phase preparation, aqueous phase preparation, and microemulsification. In the oil phase preparation sub-step S1.1, liquid paraffin is mixed with a compound surfactant, wherein the compound surfactant is a mixture of Span-80 (HLB=4.3) and Tween-80 (HLB=15.0) in a mass ratio of 4:6 to 6:4, controlling the composite HLB value to be 4.5-5.5; the total mass of the surfactant accounts for 15-25 wt% of the oil phase mass. Specifically, 100 parts (by mass) of liquid paraffin are taken, and 20 parts of the compound surfactant of Span-80 and Tween-80 are added, wherein the mass ratio of Span-80 to Tween-80 is 5:5, at which point the composite HLB value is exactly 5.0. The mixture is placed in a 60°C water bath and stirred to dissolve until a transparent and homogeneous oil phase is formed. This oil phase system provides a stable oil phase environment for subsequent microemulsification and polymerization reactions.

[0034] In the aqueous phase preparation sub-step S1.2, the polymerizable HALS monomer is dissolved in deionized water to prepare a HALS monomer solution with a monomer concentration of 30-50 wt%. A pre-dispersed nano-ceramic particle dispersion and potassium persulfate (KPS) initiator are added to the HALS monomer solution, with the initiator having a mass fraction of 0.5-1.0 wt% relative to the HALS monomer. Specifically, 30 parts of the bis(2,2,6,6-tetramethyl-4-piperidine) sebacate polymerization product (GA-80, molecular weight approximately 3500) are dissolved in 70 parts of deionized water, resulting in a HALS monomer concentration of 30 wt%. Nano-Al2O3@SiO2 composite particles (30 nm particle size, specific surface area 120 m²) pretreated with coupling agent KH-570 are then added to this solution. 2 Eight parts of HALS monomer ( / g) and 0.3 parts of initiator KPS (approximately 1.0 wt% relative to the mass fraction of HALS monomer) were then ultrasonically dispersed for 30 min to obtain a uniformly dispersed aqueous phase. Under the action of KH-570 coupling agent, the surface of the nano-ceramic particles was grafted with acryloyloxy functional groups, enhancing their compatibility and chemical bonding ability with subsequent polymerization products.

[0035] In the microemulsification sub-step S1.3, the aqueous phase is added dropwise to the oil phase under high-speed stirring (10000-15000 rpm) and ultrasonic treatment (power 200-400 W, time 10-20 min) to prepare a W / O type reverse microemulsion. The aqueous phase accounts for 10-20 wt% of the total mass of the microemulsion, and the microemulsion droplet size is 10-50 nm. Specifically, under nitrogen protection, the aqueous phase is added dropwise to the oil phase under high-speed stirring (12000 rpm) while simultaneously undergoing ultrasonic treatment (power 300 W). After the addition is complete, stirring continues for 30 min, ultimately obtaining a W / O type reverse microemulsion with a particle size of approximately 30 nm. In this microemulsion system, the distribution of the microemulsion droplet size D can be monitored in real time using L dynamic light scattering technology, and its average particle size can be obtained using the formula... Theoretical estimation is performed, among which Where is Boltzmann's constant, and T is the absolute temperature. ν is the viscosity of the continuous phase, and v is the kinematic viscosity of the microemulsion droplets. Actual tests show that the droplet size of this microemulsion is stable in the range of 10-50 nm, which meets the reaction space requirements of the subsequent polymerization reaction.

[0036] Step S2 is the in-situ polymerization preparation of the core-shell bifunctional modifier, which includes two sub-steps: polymerization reaction and post-treatment. In the polymerization reaction sub-step S2.1, the reverse microemulsion is heated to 70-80℃, preferably 75℃, and reacted for 4-6 hours, preferably 5 hours, under nitrogen protection and mechanical stirring at 400 rpm. The specific reaction mechanism is as follows: 1) The KPS initiator decomposes upon heating to generate sulfate radical ions, which attack the double bond positions of the HALS monomer (bis(2,2,6,6-tetramethyl-4-piperidine) sebacate), initiating a free radical polymerization reaction. During chain growth, the molecular chains entangle and aggregate to form a polymeric HALS core; 2) The silanyl methoxy group (-Si(OCH3)3) in the KH-570 coupling agent molecule hydrolyzes in an aqueous environment at 75℃ to generate silanyl hydroxyl groups (-Si(OH)3). Subsequently, condensation polymerization occurs between the silanyl hydroxyl groups to form a -Si-O-Si- network structure, which is chemically bonded to the surface of the polymeric HALS core, forming a coupling transition layer; 3) The KH-570 modified layer (acryloyloxy functional group) on the surface of the nano-ceramic particles undergoes a condensation reaction with the silanyl hydroxyl groups on the surface of the coupling transition layer, achieving chemical bonding and forming a nano-ceramic shell. Finally, a core-shell-shell sandwich structure is formed. Under the action of KH-570 coupling agent, nano-ceramic particles are chemically bonded to the surface of the coupling transition layer, forming a continuous and complete nano-wear-resistant ceramic shell layer. Specifically: 1) Acryloyloxy functional groups are grafted onto the surface of nano-Al2O3@SiO2 composite particles or nano-SiC particles after KH-570 pretreatment; 2) During the polymerization reaction, these functional groups undergo condensation reaction (covalent bonding) with the silanol groups on the surface of the coupling transition layer, achieving firm fixation of the nanoparticles on the surface of the coupling transition layer; 3) Multiple nanoparticles are stacked and spread on the surface of the coupling transition layer, forming a continuous ceramic shell layer with a thickness of 15-50 nm and a coverage of over 95%. In specific operation, the reverse microemulsion is heated to 75℃ and reacted for 5 hours under nitrogen protection and stirring at 400 rpm. During this reaction, the HALS monomers inside the microemulsion droplets undergo free radical polymerization under the action of KPS initiator, and the molecular chains continuously grow and entangle, forming a polymeric HALS core with a particle size of approximately 55 nm. In the KH-570 coupling agent molecule, the silanyl methoxy group (-Si(OCH3)3) undergoes hydrolysis in an aqueous environment to generate silanyl hydroxyl groups (-Si(OH)3). Subsequently, these silanyl hydroxyl groups undergo a condensation reaction to form a siloxane network structure (-Si-O-Si-), which is chemically bonded to the surface of the polymerized HALS core, forming a coupling transition layer with a thickness of approximately 10 nm. Simultaneously, the KH-570 modified layer on the surface of the nano-Al2O3@SiO2 composite particles covalently bonds with the coupling transition layer, achieving the fixation of the nano-ceramic particles on the surface of the coupling transition layer. Ultimately, a core-shell bifunctional modifier with a total particle size of approximately 120 nm is formed.

[0037] In post-processing sub-step S2.2, after the reaction is complete, ethanol is added to demulsify, followed by centrifugation. Residual surfactants are removed by washing with ethanol and deionized water sequentially. The mixture is then dried in a vacuum drying oven at 60°C for 24 hours to obtain a core-shell bifunctional modifier powder. Specifically, after the reaction, ethanol is added to the reaction system for demulsification. The demulsified mixture is then separated into solid and liquid phases using a high-speed centrifuge at 8000 rpm for 10 minutes. After collecting the solid product, it is washed three times with ethanol to remove residual oil phase and surfactants, and then twice with deionized water to remove water-soluble impurities. Finally, the washed product is placed in a vacuum drying oven and dried at 60°C for 24 hours to obtain a free-flowing core-shell bifunctional modifier powder. Laser particle size analysis shows that the average particle size of the modifier powder is 120 nm, and the polydispersity index (PDI) is 0.18, meeting the design requirements (50-200 nm range).

[0038] Step S3 is the preparation of the functional masterbatch, which includes three sub-steps: premixing, melt extrusion, and masterbatch performance testing. In the premixing sub-step S3.1, the core-shell bifunctional modifier powder and PP powder are mixed at a mass ratio of 15-25:100 in a high-speed mixer for 3-5 minutes at a speed of 1000-1500 rpm. Specifically, 20 parts of the core-shell bifunctional modifier powder and 80 parts of PP powder (MFR=25g / 10min) are added together to the high-speed mixer, and the mixing time is set to 4 minutes and the speed to 1200 rpm to ensure that the core-shell bifunctional modifier powder and PP powder are thoroughly and uniformly mixed. This premixing process ensures the initial dispersion of the core-shell bifunctional modifier in the PP matrix, laying the foundation for uniform dispersion in the subsequent melt extrusion process.

[0039] In the melt extrusion step S3.2, the mixture is added to a twin-screw extruder for melt granulation. The length-to-diameter ratio (L / D) of the twin-screw extruder is not less than 48:1, and the zone temperature is set to 180℃-190℃-200℃-210℃-220℃ (from the feed section to the die head), with a screw speed of 300-400 rpm. The screw assembly includes alternating arrangements of kneading blocks and reverse conveying elements to enhance the dispersion effect. In specific operation, the mixture is added to the twin-screw extruder (L / D = 52:1), and the zone temperature is set to 180℃-190℃-200℃-210℃-215℃-220℃ (a total of 6 temperature zones, with sequential temperature increases from the feed section to the die head), the screw speed is set to 350 rpm, and the feeding rate is 15 kg / h. The screw assembly employs an alternating arrangement of kneading blocks and reverse conveying elements. The kneading blocks are responsible for strong shearing and dispersing of the material, while the reverse conveying elements impede material flow and promote mixing. This screw assembly design can generate speeds up to 1000-1500 seconds. -1The shear rate effectively breaks down the soft aggregates of the core-shell bifunctional modifier, achieving nanoscale dispersion in the PP matrix. During extrusion, the residence time distribution of the material in each section can be characterized by a residence time distribution function, ensuring uniform heating and consistent dispersion of the material.

[0040] In the masterbatch performance testing sub-step S3.3, the content of the core-shell bifunctional modifier in the prepared functional masterbatch is 15-25 wt%, and the melt index (230℃ / 2.16kg) is 8-15 g / 10min. The following methods are used to verify the uniformity of the functional agent dispersion: 1) Initial screening with an optical microscope (400x) shows no agglomerated particles larger than 3μm; 2) Verification with a transmission electron microscope (TEM) by taking an ultrathin section of the masterbatch (thickness 60-80nm) and observing it at 50,000-100,000x magnification, the core-shell bifunctional modifier particle size distribution is uniform, with an average particle size of 80-150nm and no obvious agglomerates; 3) Verification of the fiber cross section with a scanning electron microscope (SEM) shows that the modifier is uniformly dispersed inside the PP fiber, and the maximum agglomerate size is ≤200nm; 4) Dynamic light scattering (DLS) test of the masterbatch dispersion shows that PDI ≤0.25. In practice, the prepared masterbatch underwent performance testing. The results showed a melt index of 11.2 g / 10 min, and no obvious agglomerates were observed under an optical microscope (400x), with the largest agglomerate size less than 1 μm, and the dispersion grade was A. The measured content of the core-shell bifunctional modifier in the masterbatch was 20 wt%, consistent with the design value. The melt index test was conducted using a standard capillary rheometer at a test temperature of 230℃ and a load of 2.16 kg, and the test results met the requirements for spinning processing.

[0041] Step S4 is the preparation of the PP support fabric, which includes five sub-steps: blending and dilution, melt spinning, needle punching reinforcement, hot rolling and setting, and finished product cutting. In the blending and dilution sub-step S4.1, the functional masterbatch and raw PP chips are mixed at a mass ratio of 1:4 to 1:6, and then extruded and granulated to obtain the final blend. Specifically, 25 parts of the functional masterbatch are mixed with 75 parts of the raw PP chips (MFR=30g / 10min) to control the mass fraction of the core-shell bifunctional modifier in the final blend to about 4wt%. The mixture is then added to a twin-screw extruder for re-granulation, with extrusion parameters similar to those in step S3.2, to ensure uniform distribution of the components in the blend. The melt index of the final blend is 28g / 10min, which is suitable for subsequent melt spinning processing.

[0042] In melt spinning step S4.2, the blend is melted in a screw extruder at a temperature of 240-260℃, with a spinneret orifice diameter of 0.3-0.5 mm and a spinning speed of 800-1500 m / min, to produce modified PP fibers with a fiber fineness of 1.5-6 dtex. Specifically, the blend is melted in a screw extruder with a temperature gradient of 250℃-255℃-260℃-258℃ (heating sequentially from the feed section to the spinneret), a spinneret orifice diameter of 0.4 mm, and a spinning speed of 1200 m / min. Under these conditions, after the blend melt is extruded through the spinneret, it undergoes side-blowing cooling (air temperature 20-25℃, air velocity 0.3-0.5 m / s) and winding and drawing (draw ratio 2.5-3.5), ultimately producing modified PP fibers with a fineness of 2.0 dtex. The flow behavior of the melt within the spinneret channel can be described by a power-law model, where the relationship between the melt viscosity η and the shear rate γ satisfies... Where K is the consistency coefficient and n is the non-Newtonian exponent (approximately 0.4-0.5). During the spinning process, the relationship between the fiber diameter d and the spinneret aperture D, winding speed V, and extrusion speed v can be expressed by the continuity equation. An estimation was performed. Scanning electron microscopy revealed that the core-shell bifunctional modifier was uniformly distributed within the fiber, with no obvious agglomeration observed.

[0043] In step S4.3 of the needle-punching reinforcement process, the modified PP fibers are carded into a web and then reinforced using a needle-punching process with a needle-punching density of 30-80 needles / cm. 2 The needles are selected from the 15×18×32×3 type. In specific operation, the fibers are carded into a web using a carding machine with a working width of 2.5m and a carding speed of 30-50m / min. The resulting fiber web has a surface density of 80g / m². 2 The fiber web was then fed into a needle punching machine for reinforcement, with a needle punching density set to 50 needles / cm. 2 The needles used are 15×18×32×3 type (needle handle diameter 0.7mm, needle body length 18mm, needle tip length 32mm, insertion depth 3mm), and the needling frequency is 600-800 times / min. During the needling process, the needles carry the fiber web up and down, causing the fibers to entangle and form a three-dimensional network structure. After needling reinforcement, the surface density of the nonwoven fabric increases to approximately 120g / m². 2 It has a thickness of approximately 4mm and a longitudinal breaking strength of over 50N.

[0044] In the hot rolling and setting sub-step S4.4, the needle-punched fabric is hot-rolled and set at 130-150℃ and a linear pressure of 5-20kN / m to impart a three-dimensional structure and surface embossing. The pressure roller can be a mesh roller or a dot matrix roller to form a surface embossed structure with a depth of 0.1-0.5mm. Specifically, the needle-punched fabric is fed into a hot rolling mill for setting. The hot rolling temperature is set to 140℃, the linear pressure is set to 10kN / m, and the hot rolling roller is a mesh roller (mesh diameter 0.8mm, mesh spacing 2mm). During the hot rolling process, the needle-punched fabric softens and sets under the combined action of heat and pressure, fixing the entanglement structure between fibers. Simultaneously, the raised portion of the mesh roller forms a regularly arranged embossed structure on the fabric surface, with an embossing depth of approximately 0.3mm, effectively increasing the specific surface area and surface roughness of the fabric, and improving the adhesion during subsequent coating or composite processing. After hot rolling and shaping, the thickness of the support fabric is stabilized at around 3mm, the longitudinal breaking strength is increased to over 80N, and the transverse breaking strength is increased to over 60N.

[0045] In the finished product cutting sub-step S4.5, the hot-rolled and shaped support fabric is cut to obtain the required specifications of anti-oxidation and wear-resistant PP support fabric. Specifically, a CNC cutting machine is used to precisely cut the hot-rolled and shaped support fabric. The cutting dimensions are determined according to customer requirements, with standard specifications being a width of 1.0-2.0m and a length of 10-50m / roll. After cutting, the finished product undergoes quality inspection, including appearance quality (no obvious surface defects, complete embossing), dimensional deviations (width deviation ±2cm, thickness deviation ±0.2mm), and physicochemical properties (area density, tensile strength, abrasion resistance cycles, oxidation induction period, etc.). The final product has an area density of 150g / m³. 2 Antioxidant and wear-resistant PP support fabric with a thickness of 3mm.

[0046] Optionally, this embodiment also includes a surface treatment step S5: subjecting the hot-rolled and shaped support fabric to low-temperature plasma treatment (using an O2 / Ar mixture in a ratio of 1:1 to 1:3) to further improve surface wettability and coating adhesion. Specifically, the support fabric is fed into a low-temperature plasma treatment device, using an O2 / Ar mixture (2:1 ratio) as the treatment gas, with a treatment power of 500-800W and a treatment time of 30-60 seconds. The plasma contains active particles (O atoms, Ar atoms, etc.). + The surface of the support cloth is bombarded and etched by ions, etc., while oxygen-containing functional groups (carboxyl groups, hydroxyl groups, etc.) are introduced, which reduces the contact angle of the support cloth surface from 110° to below 40°, significantly improving surface wettability and adhesion during subsequent coating processing.

[0047] To verify the technical effectiveness of this embodiment, a systematic performance test was conducted on the prepared antioxidant and abrasion-resistant PP support fabric. The abrasion resistance test was performed using a Taber abrasion tester under the following conditions: CS-10 wheel, 1000g load, 500r / min, yielding 8250 cycles. The antioxidant induction period test was conducted using a 200℃ oven aging method, with a 5% weight loss as the endpoint, yielding a result of 215 hours. The antioxidant migration test was performed using a 60℃ / 24h hexane extraction method, with the HALS content in the extract determined by high-performance liquid chromatography (HPLC), calculating a migration amount of 0.3%. The tensile strength test was conducted using a universal testing machine, yielding a longitudinal tensile strength of 125N and a transverse tensile strength of 95N. The compression resilience test was performed according to GB / T18941 standard, with a result of 92% under 30% compression.

[0048] Example 2

[0049] This embodiment relates to a preparation process of an antioxidant and wear-resistant support cloth based on modified PP. It adopts the same PP support cloth preparation step S4 as in Example 1, but the parameters are optimized in the preparation of the core-shell bifunctional modifier. Specifically, the polymerization reaction conditions and the core-shell structure ratio are adjusted in step S2.

[0050] In the preparation of core-shell bifunctional modifiers, core-shell bifunctional modifiers with different core-shell structure ratios were prepared by adjusting the concentration of HALS monomer and the amount of nano-ceramic particles added in the aqueous phase. Specifically, keeping the oil phase composition and microemulsification conditions constant, the concentration of HALS monomer (40wt%) and the amount of nano-ceramic particles added (12 parts) were changed, and the polymerization reaction conditions (reaction temperature 78℃, reaction time 6h) were adjusted accordingly to prepare a core-shell bifunctional modifier with a core particle size of approximately 95nm, a coupling transition layer thickness of approximately 12nm, a ceramic shell thickness of approximately 45nm, and a total particle size of approximately 180nm. The average particle size of the modifier powder was 180nm, and the polydispersity index (PDI) was 0.22.

[0051] The above-mentioned core-shell bifunctional modifier was used to prepare functional masterbatch according to the same step S3 as in Example 1, wherein the mass ratio of modifier powder to PP powder was 22:100, the melt extrusion temperature was slightly adjusted (the section temperature was set to 185℃-195℃-205℃-215℃-220℃-225℃), and the resulting functional masterbatch had a melt index of 10.5 g / 10 min, a functional agent content of 22 wt%, and a maximum agglomeration size of less than 1.2 μm under an optical microscope.

[0052] Subsequently, the PP support fabric was prepared following the same step S4 as in Example 1, wherein the mass ratio of functional masterbatch to raw PP chips during blending and dilution was 1:5, the melt spinning temperature was adjusted to 245℃-252℃-258℃-260℃, the spinning speed was 1100m / min, and the resulting fiber fineness was 2.5dtex. The needle-punching reinforcement parameters were adjusted to a needle-punching density of 60 needles / cm. 2 The hot rolling and setting temperature was adjusted to 145℃, the linear pressure was adjusted to 12kN / m, and the hot rolling rolls adopted dot matrix rolls (dot matrix spacing 1.5mm) to form a surface embossing structure with an embossing depth of 0.4mm. Finally, an antioxidant and wear-resistant PP support fabric with an areal density of 180g / m² and a thickness of 4mm was obtained.

[0053] Performance tests were conducted on the support fabric. The results showed that it could withstand 7500 abrasion cycles, had an antioxidant induction period of 195 hours, an antioxidant migration rate of 0.4%, longitudinal and transverse tensile strengths of 135 N and 105 N, respectively, and a compression rebound rate of 89%. This example demonstrates that by adjusting the core-shell structure ratio, abrasion resistance and antioxidant performance can be balanced to some extent. However, when the total particle size exceeds 180 nm, the dispersion uniformity decreases slightly, resulting in some performance indicators being inferior to those of Example 1.

[0054] Example 3

[0055] This embodiment relates to a preparation process of an antioxidant and wear-resistant support fabric based on modified PP, focusing on verifying the influence of the composition of the nano-ceramic shell in the core-shell structure on the performance of the final product. Compared with Example 1, this embodiment uses nano-SiC dispersion instead of nano-Al2O3@SiO2 composite particles as the shell material, while keeping the other process parameters unchanged.

[0056] In the preparation of the core-shell bifunctional modifier, nano-SiC dispersions (particle size 40 nm, specific surface area 100 m²) pretreated with KH-570 coupling agent were used. 2 The nano-Al2O3@SiO2 composite particles in Example 1 were replaced with those in Example 1 (with a Mohs hardness of 9.5). Specifically, in preparing the aqueous phase, 28 parts of the bis(2,2,6,6-tetramethyl-4-piperidine) sebacic acid ester polymerization product (GA-80) were dissolved in 72 parts of deionized water to prepare a HALS monomer concentration of 28 wt%. 10 parts of nano-SiC dispersion pretreated with KH-570 and 0.28 parts of initiator KPS were added to this solution, and the mixture was ultrasonically dispersed for 35 min to obtain the aqueous phase. The microemulsification and polymerization reaction conditions were the same as in Example 1, yielding a core-shell bifunctional modifier with a core particle size of approximately 50 nm, a coupling transition layer thickness of approximately 8 nm, a ceramic shell thickness of approximately 38 nm, and a total particle size of approximately 105 nm. The average particle size of the modifier powder was 105 nm, and the polydispersity index (PDI) was 0.16.

[0057] The above-mentioned core-shell bifunctional modifier was used to prepare functional masterbatch and PP support fabric according to the same steps S3 and S4 as in Example 1, wherein the modifier content in the functional masterbatch was 21 wt% and the melt index was 12.0 g / 10 min. After blending and dilution, the modified PP fibers with a fiber fineness of 1.8 dtex were spun and then needle-punched for reinforcement (needle punching density 45 needles / cm). 2 After hot rolling and setting (temperature 138℃, linear pressure 9kN / m, mesh roller), a surface density of 140g / m² is obtained. 2 Antioxidant and wear-resistant PP support fabric with a thickness of 2.8mm.

[0058] Performance tests were conducted on the support fabric. The results showed an abrasion resistance of 8100 cycles, an oxidation induction period of 210 hours, an antioxidant migration of 0.35%, longitudinal and transverse tensile strengths of 118 N and 88 N, respectively, and a compression rebound rate of 91%. This example demonstrates that using nano-SiC dispersion as the shell material can also achieve excellent abrasion resistance and oxidation resistance, with its abrasion resistance slightly superior to Example 1 (nano-Al2O3@SiO2 composite particles). This is attributed to the higher Mohs hardness of nano-SiC (9.5 vs. 9.0). The choice between the two nano-ceramic materials can be flexibly adjusted according to the cost and performance requirements of specific application scenarios.

[0059] Example 4

[0060] The similarities between this embodiment and Example 1 will not be repeated here. The difference lies in the following: In step S2.1, the correspondence between the polymerization reaction conditions and the core-shell structure size is as follows: When the HALS monomer concentration is 30wt% and the nano-ceramic particles are 8 parts, the polymerization temperature is 75℃ and the reaction time is 5h, the resulting core particle size is 30-80nm (preferably 55nm), the inner shell thickness is 5-15nm (preferably 10nm), the outer shell thickness is 15-30nm (preferably 25nm), and the total particle size is 50-100nm; When the HALS monomer concentration is 40wt% and the nano-ceramic particles are 12 parts, the polymerization temperature is 78℃ and the reaction time is 6h, the resulting core particle size is 80-95nm, the inner shell thickness is 10-15nm, the outer shell thickness is 30-50nm, and the total particle size is 150-200nm. By adjusting the HALS monomer concentration and the amount of nano-ceramic particles added, the core-shell structure size can be precisely controlled.

[0061] Example 5

[0062] The similarities between this embodiment and Embodiment 1 will not be repeated here. The differences are as follows: the melt flow index of the PP fiber matrix is ​​20-35 g / 10 min; and the surface density of the supporting fabric is 80-300 g / m². 2 The thickness is 1-10mm; the surface of the support fabric has an embossed structure with a depth of 0.1-0.5mm.

[0063] The support fabric of this invention is applicable to the following specific application scenarios: 1) Geosynthetics: As a support layer for geogrids, it is connected to the geogrid through mechanical interlocking of the embossed structure, used to enhance slope protection, retaining walls, and other projects; 2) Filter materials: As a supporting skeleton for filter bags, it is fixed to the filter bag fabric by thermal bonding or sewing, used for industrial dust removal and liquid filtration; 3) Building waterproofing: As a reinforcing layer for waterproof membranes, it is bonded to the waterproof membrane by adhesive, used for roofing and underground waterproofing. The preferred depth of the embossed structure is 0.3mm, and the embossed shape can be diamond, dot matrix, or grid, with an embossed spacing of 2-5mm.

[0064] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An antioxidant and wear-resistant support fabric based on modified PP, characterized in that, The product comprises a PP fiber matrix and a core-shell bifunctional modifier uniformly dispersed in the PP fiber matrix. The core-shell bifunctional modifier has a core-shell-shell sandwich structure, comprising a core, an inner shell covering the surface of the core, and an outer shell covering the surface of the inner shell. The core is a polymer segment of a polymeric hindered amine light stabilizer. The inner shell is a coupling transition layer composed of the hydrolysis and condensation product of γ-methacryloyloxypropyltrimethoxysilane. The outer shell is a nano-wear-resistant ceramic shell. The total particle size of the core-shell bifunctional modifier is 50-200 nm, and its mass fraction in the PP fiber matrix is ​​3-5 wt%.

2. The antioxidant and wear-resistant support fabric based on modified PP according to claim 1, characterized in that, The core particle size is 30-80 nm, the weight-average molecular weight is 3000-8000, and the polymerizable hindered amine light stabilizer is selected from the polymer product of sebacate bis(2,2,6,6-tetramethyl-4-piperidine) ester or the condensation product of 2,2,6,6-tetramethyl-4-piperidine alcohol and diacid; the inner shell thickness is 5-15 nm.

3. The antioxidant and wear-resistant support fabric based on modified PP according to claim 2, characterized in that, The nano-wear-resistant ceramic shell has a thickness of 15-50 nm and is composed of nano-Al2O3@SiO2 composite particles or nano-SiC dispersions; the nanoparticles have a particle size of 10-50 nm and a specific surface area of ​​50-200 m². 2 / g, Mohs hardness ≥9.

4. The antioxidant and wear-resistant support fabric based on modified PP according to claim 3, characterized in that, The PP fiber matrix has a melt flow index of 20-35 g / 10 min; the supporting fabric has a surface density of 80-300 g / m³. 2 The thickness is 1-10mm; the surface of the support fabric has an embossed structure with a depth of 0.1-0.5mm.

5. The preparation process of the antioxidant and wear-resistant support fabric based on modified PP according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Preparation of W / O type reverse microemulsion; S2. In-situ polymerization to prepare core-shell bifunctional modifier powder; S3. Melt extrusion preparation of functional masterbatch; S4. After blending and dilution, the support fabric is obtained by melt spinning, needle punching reinforcement, and hot rolling.

6. The preparation process of the antioxidant and wear-resistant support fabric based on modified PP according to claim 5, characterized in that, step... In S1, the oil phase contains a combination of Span-80 and Tween-80 surfactants in a mass ratio of 4:6 to 6:4, with a combined HLB value of 4.5-5.

5. The surfactant accounts for 15-25 wt% of the oil phase, and the aqueous phase accounts for 10-20 wt% of the total microemulsion mass. The aqueous phase contains 30-50 wt% HALS monomer and 0.5-1.0 wt% potassium persulfate initiator. The microemulsion conditions are: stirring speed 10000-15000 rpm, ultrasonic power 200-400 W, ultrasonic time 10-20 min, aqueous phase droplet rate 0.5 mL / min, and microemulsion droplet size 10-50 nm.

7. The preparation process of the antioxidant and wear-resistant support fabric based on modified PP according to claim 5, characterized in that, In step S2, the polymerization temperature is 70-80℃, and the reaction is carried out under nitrogen protection and stirring at 300-500 rpm for 4-6 hours, with a HALS monomer conversion rate of >95%. Ethanol is used for demulsification, followed by centrifugation at 8000 rpm for 10 minutes, washing with ethanol and deionized water in sequence, and vacuum drying at 60℃ for 24 hours to obtain the modifier powder.

8. The preparation process of the antioxidant and wear-resistant support fabric based on modified PP according to claim 5, characterized in that, In step S3, the modifier powder and PP powder are mixed at a mass ratio of 15-25:100 at 1000-1500 rpm for 3-5 min; the twin-screw extruder has an L / D ratio ≥ 48:1, the screws are arranged with alternating kneading blocks and reverse conveying elements, the extrusion temperature is 180-220℃, and the screw speed is 300-400 rpm; the resulting masterbatch has a modifier content of 15-25 wt% and a melt index of 8-15 g / 10 min.

9. The preparation process of the antioxidant and wear-resistant support fabric based on modified PP according to claim 5, characterized in that, In step S4, the mass ratio of functional masterbatch to raw PP chips is 1:4 to 1:6; the melt spinning temperature is 240-260℃, the spinneret orifice diameter is 0.3-0.5mm, the spinning speed is 800-1500m / min, the draw ratio is 2.5-3.5, the fiber fineness is 1.5-6dex, and the needle punching density is 30-80 needles / cm. 2 The needle type is 15×18×32×3, the needle punching frequency is 600-800 times / min; the hot rolling temperature is 130-150℃, and the linear pressure is 5-20kN / m.

10. The preparation process of the antioxidant and wear-resistant support fabric based on modified PP according to claim 9, characterized in that, It also includes low-temperature plasma surface treatment of the support fabric. The low-temperature plasma treatment uses a mixture of oxygen and argon in a ratio of 1:1 to 1:3, with a treatment power of 500-800W and a treatment time of 30-60s, to improve the surface wettability of the support fabric and the adhesion of the coating.

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