High-strength fireproof sheath material for cable and preparation process thereof
By treating and dispersing modified aluminum hydroxide and glass fiber, combined with the transitional effect of enzymatic hydrolysis of lignin, the modulus mismatch problem of cable sheath material was solved, and the preparation of high-strength fireproof sheath was achieved, improving tensile strength and resistance to bending fatigue.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGSU HONGFENG CABLE GROUP
- Filing Date
- 2026-03-26
- Publication Date
- 2026-05-29
AI Technical Summary
The addition of flame-retardant fillers to existing cable sheath materials results in a mismatch between the modulus of the inorganic filler and the polymer matrix, leading to a decrease in tensile strength and resistance to bending fatigue, making it difficult to meet the requirements of high-reliability engineering materials.
Aluminum hydroxide and glass fiber were treated with GPTS hydrolysate to prepare modified microparticles, which were then uniformly dispersed in a polymer matrix composed of a polyurethane network and EVA. Through the transitional effect of enzymatic hydrolysis of lignin, the interfacial bonding and stress distribution were improved, forming a dense carbon layer to enhance fire resistance and flame retardancy.
This technology enables cable sheath materials to maintain excellent fire-retardant properties while significantly improving tensile strength and resistance to bending fatigue, effectively alleviating the modulus mismatch problem between inorganic fillers and polymer matrix.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer composite material preparation technology, and particularly relates to a high-strength fireproof sheath material for cables and its preparation process. Background Technology
[0002] As functional polymers, flame-retardant composite materials play a crucial role in cable sheathing materials where stringent requirements for flame retardancy and mechanical reliability are necessary. In existing technologies, polyolefins or thermoplastic elastomers are commonly used as the polymer matrix for sheathing materials. While these materials possess excellent flexibility and melt processing properties, they lack flame-retardant elements in their molecular chains. When heated and burning, they are prone to melting and dripping, releasing flammable gases. Their intrinsic flame-retardant properties are insufficient, making it difficult to meet the high-safety-level fire-resistant sheathing requirements of modern cables.
[0003] To improve the fire resistance and flame retardant properties of the sheath, a large amount of flame retardant filler is usually added to the sheath material. For example, the low-smoke halogen-free flame retardant cable sheath disclosed in Chinese patent application CN116543965A has the following raw material composition by weight: 14-16 parts SBS, 9-12 parts metallocene polyethylene, 8-10 parts aromatic oil, 8-10 parts diethylenetriamine, 48-52 parts magnesium hydroxide, 20-28 parts aluminum hydroxide, 6-8 parts charring agent, 5-8 parts smoke suppressant, 0.4-0.6 parts antioxidant, 0.8-1.2 parts silicone oil, and 1.2-1.6 parts carbon black. This scheme prepares a sheath material by adding a large amount of magnesium hydroxide and aluminum hydroxide to the polymer matrix. Although it improves the fire retardant properties of the sheath, the large difference in elastic modulus between magnesium hydroxide and aluminum hydroxide as inorganic fillers and the polymer matrix results in a significant mechanical property mismatch. Stress is difficult to be effectively transferred and evenly distributed at the interface, leading to a significant decrease in the tensile strength and bending fatigue resistance of the sheath made from this material, making it difficult to use as a high-reliability engineering material. Summary of the Invention
[0004] This invention provides a high-strength fire-resistant sheath material for cables and its preparation process, which alleviates stress concentration caused by modulus mismatch between inorganic fillers and polymer matrix, so that the sheath made of the material has high tensile strength and excellent resistance to bending fatigue while achieving excellent fire-retardant properties.
[0005] To solve the above problems, the present invention adopts the following technical solution:
[0006] A high-strength fire-resistant sheath material for cables and its preparation process, comprising the following steps:
[0007] S1. Modified aluminum hydroxide is obtained by treating aluminum hydroxide with GPTS hydrolysate and enzymatic hydrolysis of lignin; modified glass fiber is obtained by treating glass fiber with GPTS hydrolysate; modified aluminum hydroxide and modified glass fiber are dispersed in DMF, reacted with nucleophilic catalyst, reacted with MEA, and after washing and drying, microparticles are obtained.
[0008] S2. Disperse the microparticles in polycaprolactone diol, add MDI to react, add BDO to react, let stand to solidify, pulverize and granulate to obtain masterbatch;
[0009] S3. Mix the masterbatch, EVA, EVA-g-MAH, antioxidant, and lubricant to obtain a high-strength fireproof sheath material for cables.
[0010] In this invention, microparticles composed of modified aluminum hydroxide and modified glass fiber are uniformly dispersed in a polyurethane network composed of polycaprolactone diol, MDI (4,4'-diphenylmethane diisocyanate), and BDO (1,4-butanediol). After curing, pulverizing, and granulation, a masterbatch is prepared. The masterbatch is mixed with EVA (ethylene-vinyl acetate copolymer) and the microparticles are uniformly dispersed in a polymer matrix composed of polyurethane network and EVA to obtain a high-strength fire-resistant sheath material for cables. Through the transitional effect of enzymatic hydrolysis of lignin, the sheath made of the material not only has good fire resistance but also effectively improves its tensile strength and resistance to bending fatigue.
[0011] In the preparation of microparticles, aluminum hydroxide is treated with GPTS (γ-glycidyl etheroxypropyltrimethoxysilane) and enzymatically hydrolyzed lignin to obtain modified aluminum hydroxide with enzymatically hydrolyzed lignin on its surface. Glass fibers are treated with GPTS hydrolysate to obtain modified glass fibers with epoxy groups on their surface. Under the catalysis of a nucleophilic catalyst, a ring-opening reaction occurs between the hydroxyl groups of the enzymatically hydrolyzed lignin and the epoxy groups on the surface of the modified glass fibers. The modified glass fibers are covalently linked to the modified aluminum hydroxide. Subsequently, the unreacted epoxy groups on the surface of the modified glass fibers undergo a ring-opening reaction with the primary amino groups of MEA (ethanolamine) to generate hydroxyl and secondary amino groups, thus obtaining microparticles. In the preparation of the masterbatch, the hydroxyl groups of the enzymatically hydrolyzed lignin, the hydroxyl groups and secondary amino groups on the surface of the modified glass fibers react with the isocyanate groups of MDI, causing the microparticles to be covalently bonded in the polyurethane network. This significantly improves the interfacial bonding force between the polymer matrix and the microparticles, enhancing the tensile strength of the sheath. Tensile strength: The addition of modified glass fiber helps improve the tensile strength of the sheath. At the same time, the modified glass fiber is covalently linked to the modified aluminum hydroxide, effectively reducing the direct contact area between the high-modulus modified glass fiber and the polymer matrix. Furthermore, enzymatic hydrolyzed lignin, as a gradient modulus component between aluminum hydroxide and the polymer matrix, can dissipate energy through molecular chain movement under stress, mitigate the abrupt change in elastic modulus at the interface between particles and the polymer matrix, suppress stress concentration, and significantly improve the sheath's resistance to bending fatigue. In addition, enzymatic hydrolyzed lignin is rich in phenolic hydroxyl groups and aromatic ring structures, which are prone to dehydration and carbonization under heating conditions, forming a dense and continuous carbon layer. This carbon layer coats the surface of aluminum hydroxide and is supported by modified glass fiber, inhibiting polymer melt flow and droplet formation. Meanwhile, aluminum hydroxide absorbs heat at high temperatures, decomposes, and releases water vapor, reducing the temperature of the surrounding flame and diluting flammable gases, thus improving the fire resistance and flame retardancy of the sheath.
[0012] Furthermore, the GPTS hydrolysate is prepared by mixing GPTS and 90-92wt% ethanol solution, adding acetic acid solution dropwise to adjust the pH to 4-5, and reacting for 1-2 hours to obtain the GPTS hydrolysate.
[0013] Furthermore, the modified aluminum hydroxide is prepared by the following method: aluminum hydroxide is dispersed in GPTS hydrolysate for reaction treatment, filtered, washed and then dispersed in DMSO, enzymatically hydrolyzed lignin is added and mixed, triethylamine is added after heating for reaction treatment, and the modified aluminum hydroxide is obtained after filtration, washing and drying.
[0014] Further, the aluminum hydroxide is dispersed in GPTS hydrolysate, heated to 55-65℃ and reacted for 2-3 hours. After filtration, it is washed with deionized water, anhydrous ethanol, and DMSO, then dispersed in DMSO. Enzymatically hydrolyzed lignin is added and mixed well. The temperature is raised to 78-82℃, triethylamine is added and reacted for 2-3 hours. After filtration and washing with anhydrous ethanol, it is dried in an environment of 50-60℃ and 10-20 kPa for 20-24 hours to obtain modified aluminum hydroxide.
[0015] The metallic hydroxyl groups on the surface of aluminum hydroxide undergo a condensation reaction with the silanols generated by the hydrolysis of GPTS under acidic conditions, resulting in the covalent grafting of epoxy groups onto the surface of aluminum hydroxide. The hydroxyl and epoxy groups in the enzymatically hydrolyzed lignin undergo a ring-opening reaction, thus covalently linking the enzymatically hydrolyzed lignin to the surface of aluminum hydroxide, resulting in modified aluminum hydroxide with enzymatically hydrolyzed lignin on its surface. The residual hydroxyl groups on the enzymatically hydrolyzed lignin still have reactivity, providing a molecular basis for the subsequent ring-opening reaction with the epoxy groups on the surface of modified glass fiber.
[0016] Furthermore, the modified glass fiber is prepared by dispersing glass fiber in GPTS hydrolysate, stirring at 300-400 rpm for 3-4 hours, filtering, washing with anhydrous ethanol, and drying in an environment of 50-60°C and 10-20 kPa for 18-22 hours to obtain the modified glass fiber.
[0017] A condensation reaction occurs between the silanols on the surface of the glass fiber and the silanols generated by the hydrolysis of GPTS, resulting in modified glass fiber with abundant epoxy groups on the surface. This provides abundant active sites for subsequent ring-opening reactions with the hydroxyl groups of enzymatically hydrolyzed lignin, which is beneficial for the fixed attachment of modified aluminum hydroxide to the modified glass fiber.
[0018] Furthermore, in step S1, modified glass fiber and modified aluminum hydroxide are dispersed in DMF, and a nucleophilic catalyst DMAP is added and reacted for 5-6 hours. MEA is added and reacted for 30-50 minutes. After filtration, the mixture is washed with DMF and anhydrous ethanol and then dried in an environment of 50-60°C and 10-15 kPa for 10-12 hours to obtain microparticles.
[0019] Under the catalysis of the nucleophilic catalyst DMAP (4-dimethylaminopyridine), the epoxy groups on the surface of the modified glass fiber can undergo a ring-opening reaction with the hydroxyl groups of the enzymatically hydrolyzed lignin, allowing the modified glass fiber to be covalently linked to the surface of the modified aluminum hydroxide. This reduces the contact area between the modified glass fiber and the polymer matrix, which helps to mitigate the impact of the addition of modified glass fiber on the bending fatigue resistance of the sheath.
[0020] Furthermore, in step S2, the microparticles are dispersed in polycaprolactone diol at 80-85°C, cooled to 50-60°C, and MDI is added under an inert atmosphere and reacted for 1-2 hours. BDO is then added, and the mixture is heated to 78-82°C and reacted for 1-2 hours. The mixture is then allowed to stand for 20-24 hours at 40-50°C and 10-20 kPa. After pulverization, the mixture is fed into an extruder for extrusion at a temperature of 185-190°C and a screw speed of 200-250 rpm. The extrudate is then air-cooled and pelletized to obtain masterbatch.
[0021] The microparticles are pre-dispersed uniformly in polycaprolactone diol, and then MDI and BDO are added to react. The low viscosity of polycaprolactone diol in the early stage of the reaction is used to achieve uniform dispersion and full wetting of the microparticles. As the polyurethane network is formed, the viscosity of the system rises rapidly, and the microparticles are effectively fixed to prevent them from agglomerating in subsequent processing, thereby ensuring that the microparticles are uniformly distributed in the masterbatch.
[0022] A high-strength fire-resistant sheath material for cables comprises the following raw materials in parts by weight: 18-22 parts masterbatch, 58-64 parts EVA, 9-12 parts EVA-g-MAH, 0.4-0.6 parts antioxidant 1010, and 1.3-1.6 parts lubricant polyethylene wax; wherein the masterbatch comprises the following raw materials in parts by weight: 9-12 parts microparticles, 88-93 parts polycaprolactone diol, 14-16 parts MDI, and 2.3-2.9 parts BDO.
[0023] Furthermore, the microparticles comprise the following parts by weight of raw materials: 9-12 parts modified glass fiber, 18-21 parts modified aluminum hydroxide, 0.2-0.3 parts DMAP, and 0.2-0.3 parts MEA; the modified aluminum hydroxide comprises the following parts by weight of raw materials: 17-21 parts aluminum hydroxide, 210-220 parts GPTS hydrolysate, 9-12 parts enzymatically hydrolyzed lignin, and 0.1-0.2 parts triethylamine; the modified glass fiber comprises the following parts by weight of raw materials: 20-23 parts glass fiber and 250-260 parts GPTS hydrolysate.
[0024] Furthermore, the GPTS hydrolysate comprises the following raw materials in parts by weight: 15-18 parts by weight of GPTS and 570-580 parts by weight of 90-92 wt% ethanol solution.
[0025] The present invention has the following beneficial effects:
[0026] This invention obtains a high-strength fire-resistant sheath material for cables by uniformly dispersing microparticles in a polymer matrix composed of a polyurethane network and EVA. Sheaths made from this material have excellent fire-retardant properties, as well as good tensile strength and resistance to bending fatigue. The microparticles consist of modified aluminum hydroxide coated with enzymatically hydrolyzed lignin and modified glass fibers covalently bonded to the modified aluminum hydroxide. The hydroxyl and secondary amino groups in the microparticles can react with the isocyanate groups of MDI, covalently bonding the microparticles to a polyurethane network. Subsequently, a masterbatch is prepared, which is then blended and extruded with EVA and other materials. The microparticles are uniformly dispersed in the polymer matrix formed by polyurethane and EVA, significantly enhancing the interfacial bonding force between the microparticles and the polymer matrix and improving the tensile strength of the sheath. Enzymatically hydrolyzed lignin, as a flexible transition layer with a modulus between aluminum hydroxide and the polymer matrix, effectively mitigates abrupt changes in the interfacial elastic modulus, inhibits stress concentration during bending, and improves the sheath's resistance to bending fatigue. In a fire environment, aluminum hydroxide decomposes endothermally, releasing water vapor to dilute flammable gases, while enzymatically hydrolyzed lignin dehydrates and carbonizes to form a dense, continuous carbon layer that encapsulates the aluminum hydroxide. Glass fibers not only improve the tensile strength of the sheath but also act as a skeleton to support the carbon layer, effectively preventing dripping and heat transfer, and enhancing the fire resistance and flame retardancy of the sheath. Detailed Implementation
[0027] Example 1
[0028] Mix 15g GPTS and 570g 90wt% ethanol solution, adjust the pH to 4.5 by adding 5wt% acetic acid solution dropwise, and stir at 300rpm for 2h to obtain GPTS hydrolysate. Add 20g aluminum hydroxide with a particle size of 1μm to 210g GPTS hydrolysate, stir at 1000rpm for 30min, heat to 60℃, stir at 500rpm for 3h, filter, wash 3 times with deionized water, 2 times with anhydrous ethanol, and 2 times with DMSO (dimethyl sulfoxide), and add to 100g In DMSO, the mixture was stirred at 900 rpm for 15 min, then 10 g of enzymatically hydrolyzed lignin was added, and the mixture was stirred at 500 rpm for 20 min. The temperature was raised to 80 °C, and 0.2 g of triethylamine was added. The mixture was stirred at 350 rpm for 3 h, filtered, washed four times with anhydrous ethanol, and dried at 60 °C and 20 kPa for 24 h to obtain modified aluminum hydroxide. 23 g of glass fibers with a diameter of 10 μm and a length of 0.2 mm were added to 260 g of GPTS hydrolysate, stirred at 1000 rpm for 30 min, and then stirred at 300 rpm for 4 h. The mixture was filtered, washed three times with anhydrous ethanol, and dried at 60 °C and 20 kPa for 20 h to obtain modified glass fibers. 10 g of modified glass fibers and 20 g of modified aluminum hydroxide were added to 450 g of DMF (N,N-dimethylformamide), stirred at 1200 rpm for 30 min, then 0.2 g of DMAP was added, and the mixture was stirred at 150 rpm for 6 h. Finally, 0.2 g of DMAP was added. MEA was stirred at 300 rpm for 50 min, filtered, washed twice with DMF, washed twice with anhydrous ethanol, and dried at 60°C and 15 kPa for 12 h to obtain microparticles.
[0029] Mix 10g of microparticles with 90g of M n 2000 g / mol of polycaprolactone diol was mixed, heated to 80°C, stirred at 1000 rpm for 30 min, cooled to 60°C, and 14 g of MDI was added under nitrogen protection. The mixture was stirred at 300 rpm for 2 h, and then 2.5 g of BDO was added. The mixture was heated to 80°C and stirred at 300 rpm for 2 h. The mixture was poured into a mold and allowed to stand for 24 h at 50°C and 20 kPa. The mixture was then pulverized in a pulverizer, and the fragments were fed into an extruder and extruded at 190°C and a screw speed of 200 rpm. The extrudate was air-cooled and pelletized to obtain masterbatch.
[0030] At 80℃, 20g masterbatch, 60g EVA (MFR=1.8g / 10min), 10g EVA-g-MAH (maleic anhydride grafted ethylene-vinyl acetate copolymer), 0.5g antioxidant 1010 and 1.5g M... n 1500 g / mol polyethylene wax was added to a high-speed mixer and stirred at 1000 rpm for 10 min to obtain a high-strength fireproof sheath material for cables.
[0031] Example 2
[0032] 15g of GPTS and 570g of 90wt% ethanol solution were mixed, and 5wt% acetic acid solution was added dropwise to adjust the pH to 4.5. The mixture was stirred at 300rpm for 2h to obtain GPTS hydrolysate. 17g of aluminum hydroxide with a particle size of 1μm was added to 215g of GPTS hydrolysate, and the mixture was stirred at 1000rpm for 30min. The temperature was raised to 60℃, and the mixture was stirred at 500rpm for 3h. The mixture was filtered, washed 3 times with deionized water, 2 times with anhydrous ethanol, and 2 times with DMSO. The mixture was then added to 106g of DMSO, and stirred at 900rpm for 15min. 9g of enzymatically hydrolyzed lignin was added, and the mixture was stirred at 500rpm for 20min. The temperature was raised to 80℃, and 0.2g of triethylamine was added. The mixture was stirred at 350rpm for 3h, filtered, washed 4 times with anhydrous ethanol, and dried at 60°C and 20kPa for 24h to obtain modified aluminum hydroxide. 23g of glass fibers with a diameter of 10μm and a length of 0.2mm were dispersed in 260g of... In GPTS hydrolysate, the mixture was stirred at 1000 rpm for 30 min, then stirred at 300 rpm for 4 h. After filtration, the mixture was washed three times with anhydrous ethanol and dried at 60°C and 20 kPa for 20 h to obtain modified glass fiber. 9 g of modified glass fiber and 18 g of modified aluminum hydroxide were added to 450 g of DMF, and the mixture was stirred at 1200 rpm for 30 min. Then, 0.2 g of DMAP was added, and the mixture was stirred at 150 rpm for 6 h. Finally, 0.2 g of MEA was added, and the mixture was stirred at 300 rpm for 50 min. After filtration, the mixture was washed twice with DMF and twice with anhydrous ethanol, and dried at 60°C and 15 kPa for 12 h to obtain microparticles.
[0033] 9g of microparticles were mixed with 93g of M n 2000 g / mol of polycaprolactone diol was mixed, heated to 80°C, stirred at 1000 rpm for 30 min, cooled to 60°C, and 15 g of MDI was added under nitrogen protection. The mixture was stirred at 300 rpm for 2 h, and then 2.3 g of BDO was added. The mixture was heated to 80°C and stirred at 300 rpm for 2 h. The mixture was poured into a mold and allowed to stand for 24 h at 50°C and 20 kPa. The mixture was then fed into a pulverizer to be pulverized. The fragments were fed into an extruder and extruded at 190°C and a screw speed of 200 rpm. The extrudate was air-cooled and pelletized to obtain masterbatch.
[0034] The mixture consisted of 18g masterbatch, 64g EVA (MFR=1.8g / 10min), 9g EVA-g-MAH, 0.5g antioxidant 1010, and 1.5g M... n 1500 g / mol polyethylene wax was added to a high-speed mixer and stirred at 1000 rpm for 10 min to obtain a high-strength fireproof sheath material for cables.
[0035] Example 3
[0036] 18g of GPTS and 580g of 91wt% ethanol solution were mixed, and 5wt% acetic acid solution was added dropwise to adjust the pH to 4. The mixture was stirred at 350rpm for 1.5h to obtain GPTS hydrolysate. 20g of aluminum hydroxide with a particle size of 1μm was added to 220g of GPTS hydrolysate, and the mixture was stirred at 1000rpm for 30min. The temperature was raised to 55℃, and the mixture was stirred at 600rpm for 2h. The mixture was filtered, washed 3 times with deionized water, 2 times with anhydrous ethanol, and 2 times with DMSO. The mixture was then added to 103g of DMSO, and stirred at 900rpm for 15min. 11g of enzymatically hydrolyzed lignin was added, and the mixture was stirred at 500rpm for 20min. The temperature was raised to 78℃, and 0.15g of triethylamine was added. The mixture was stirred at 450rpm for 2h, and the mixture was filtered, washed 4 times with anhydrous ethanol, and dried at 50°C and 10kPa for 20h to obtain modified aluminum hydroxide. 22g of glass fiber with a diameter of 10μm and a length of 0.2mm was added to 255g of... In GPTS hydrolysate, the mixture was stirred at 1000 rpm for 30 min, then stirred at 350 rpm for 3.5 h. After filtration, the mixture was washed three times with anhydrous ethanol and dried at 50°C and 10 kPa for 22 h to obtain modified glass fiber. 11 g of modified glass fiber and 19 g of modified aluminum hydroxide were added to 400 g of DMF and stirred at 1200 rpm for 30 min. 0.25 g of DMAP was added and the mixture was stirred at 180 rpm for 5 h. 0.25 g of MEA was added and the mixture was stirred at 400 rpm for 30 min. After filtration, the mixture was washed twice with DMF and twice with anhydrous ethanol and dried at 50°C and 10 kPa for 10 h to obtain microparticles.
[0037] Mix 10g of microparticles with 91g of M n 2000 g / mol of polycaprolactone diol was mixed, heated to 82°C, stirred at 1000 rpm for 30 min, cooled to 55°C, and 16 g of MDI was added under nitrogen protection. The mixture was stirred at 350 rpm for 1.5 h, and 2.7 g of BDO was added. The mixture was heated to 78°C and stirred at 350 rpm for 1.5 h. The mixture was poured into a mold and allowed to stand at 40°C and 10 kPa for 20 h. The mixture was then fed into a pulverizer to be pulverized. The fragments were fed into an extruder and extruded at 185°C and a screw speed of 220 rpm. The extrudate was air-cooled and pelletized to obtain masterbatch.
[0038] The mixture consisted of 19g masterbatch, 62g EVA (MFR=1.8g / 10min), 11g EVA-g-MAH, 0.4g antioxidant 1010, and 1.6g M... n 1500 g / mol polyethylene wax was added to a high-speed mixer and stirred at 1000 rpm for 10 min to obtain a high-strength fireproof sheath material for cables.
[0039] Example 4
[0040] 18g of GPTS and 580g of 91wt% ethanol solution were mixed, and 5wt% acetic acid solution was added dropwise to adjust the pH to 4. The mixture was stirred at 350rpm for 1.5h to obtain GPTS hydrolysate. 21g of aluminum hydroxide was added to 210g of GPTS hydrolysate, and the mixture was stirred at 1000rpm for 30min. The temperature was raised to 55℃, and the mixture was stirred at 600rpm for 2h. The mixture was filtered, washed 3 times with deionized water, 2 times with anhydrous ethanol, and 2 times with DMSO. The mixture was then added to 95g of DMSO, and stirred at 900rpm for 15min. 12g of enzymatically hydrolyzed lignin was added, and the mixture was stirred at 500rpm for 20min. The temperature was raised to 78℃, and 0.15g of triethylamine was added. The mixture was stirred at 450rpm for 2h, and the mixture was filtered. The mixture was washed 4 times with anhydrous ethanol and dried at 50°C and 10kPa for 20h to obtain modified aluminum hydroxide. 20g of glass fiber with a diameter of 10μm and a length of 0.2mm was added to 250g of... In GPTS hydrolysate, the mixture was stirred at 1000 rpm for 30 min, then stirred at 350 rpm for 3.5 h. After filtration, the mixture was washed three times with anhydrous ethanol and dried at 50°C and 10 kPa for 22 h to obtain modified glass fiber. 12 g of modified glass fiber and 20 g of modified aluminum hydroxide were added to 425 g of DMF and stirred at 1200 rpm for 30 min. 0.3 g of DMAP was added, and the mixture was stirred at 170 rpm for 5.5 h. 0.3 g of MEA was added, and the mixture was stirred at 350 rpm for 40 min. After filtration, the mixture was washed twice with DMF and twice with anhydrous ethanol and dried at 50°C and 10 kPa for 10 h to obtain microparticles.
[0041] 11g of microparticles were mixed with 88g of M n 2000 g / mol of polycaprolactone diol was mixed, heated to 82°C, stirred at 1000 rpm for 30 min, cooled to 55°C, and 14 g of MDI was added under nitrogen protection. The mixture was stirred at 350 rpm for 1.5 h, and 2.8 g of BDO was added. The mixture was heated to 78°C and stirred at 350 rpm for 1.5 h. The mixture was poured into a mold and allowed to stand at 40°C and 10 kPa for 20 h. The mixture was then fed into a pulverizer to be pulverized. The fragments were fed into an extruder and extruded at 185°C and a screw speed of 220 rpm. The extrudate was air-cooled and pelletized to obtain masterbatch.
[0042] The mixture consisted of 20g masterbatch, 60g EVA (MFR=1.8g / 10min), 12g EVA-g-MAH, 0.4g antioxidant 1010, and 1.6g M... n 1500 g / mol polyethylene wax was added to a high-speed mixer and stirred at 1000 rpm for 10 min to obtain a high-strength fireproof sheath material for cables.
[0043] Example 5
[0044] 17g of GPTS and 575g of 92wt% ethanol solution were mixed, and 5wt% acetic acid solution was added dropwise to adjust the pH to 5. The mixture was stirred at 400rpm for 1h to obtain GPTS hydrolysate. 18g of aluminum hydroxide was added to 215g of GPTS hydrolysate, and the mixture was stirred at 1000rpm for 30min. The temperature was raised to 65℃, and the mixture was stirred at 550rpm for 2.5h. The mixture was filtered, washed three times with deionized water, twice with anhydrous ethanol, and twice with DMSO. The mixture was then added to 98g of DMSO, and stirred at 900rpm for 15min. 9g of enzymatically hydrolyzed lignin was added, and the mixture was stirred at 500rpm for 20min. The temperature was raised to 82℃, and 0.1g of triethylamine was added. The mixture was stirred at 400rpm for 2.5h, filtered, washed four times with anhydrous ethanol, and dried at 55°C and 15kPa for 22h to obtain modified aluminum hydroxide. 20g of glass fiber with a diameter of 10μm and a length of 0.2mm was added to 250g of... In GPTS hydrolysate, the mixture was stirred at 1000 rpm for 30 min, then stirred at 400 rpm for 3 h. After filtration, the mixture was washed three times with anhydrous ethanol and dried at 55°C and 15 kPa for 18 h to obtain modified glass fiber. 9 g of modified glass fiber and 21 g of modified aluminum hydroxide were dispersed in 425 g of DMF and stirred at 1200 rpm for 30 min. 0.3 g of DMAP was added, and the mixture was stirred at 170 rpm for 5.5 h. 0.3 g of MEA was added, and the mixture was stirred at 350 rpm for 40 min. After filtration, the mixture was washed twice with DMF and twice with anhydrous ethanol and dried at 55°C and 12 kPa for 11 h to obtain microparticles.
[0045] Mix 12g of microparticles with 89g of M n 2000 g / mol of polycaprolactone diol was mixed, heated to 85°C, stirred at 1000 rpm for 30 min, cooled to 50°C, and 15 g of MDI was added under nitrogen protection. The mixture was stirred at 400 rpm for 1 h, and 2.9 g of BDO was added. The mixture was heated to 82°C and stirred at 400 rpm for 1 h. The mixture was poured into a mold and allowed to stand at 45°C and 15 kPa for 22 h. The mixture was then fed into a pulverizer to be pulverized. The fragments were fed into an extruder and extruded at 187°C and a screw speed of 250 rpm. The extrudate was air-cooled and pelletized to obtain masterbatch.
[0046] The mixture consisted of 21g masterbatch, 59g EVA (MFR=1.8g / 10min), 10g EVA-g-MAH, 0.6g antioxidant 1010, and 1.3g M... n 1500 g / mol polyethylene wax was added to a high-speed mixer and stirred at 1000 rpm for 10 min to obtain a high-strength fireproof sheath material for cables.
[0047] Example 6
[0048] 17g of GPTS and 575g of 92wt% ethanol solution were mixed, and 5wt% acetic acid solution was added dropwise to adjust the pH to 5. The mixture was stirred at 400rpm for 1h to obtain GPTS hydrolysate. 19g of aluminum hydroxide was added to 220g of GPTS hydrolysate, and the mixture was stirred at 1000rpm for 30min. The temperature was raised to 65℃, and the mixture was stirred at 550rpm for 2.5h. The mixture was filtered, washed three times with deionized water, twice with anhydrous ethanol, and twice with DMSO. The mixture was then added to 102g of DMSO, and stirred at 900rpm for 15min. 11g of enzymatically hydrolyzed lignin was added, and the mixture was stirred at 500rpm for 20min. The temperature was raised to 82℃, and 0.1g of triethylamine was added. The mixture was stirred at 400rpm for 2.5h, filtered, washed four times with anhydrous ethanol, and dried at 55°C and 15kPa for 22h to obtain modified aluminum hydroxide. 22g of glass fiber with a diameter of 10μm and a length of 0.2mm was added to 255g of... In GPTS hydrolysate, the mixture was stirred at 1000 rpm for 30 min, then stirred at 400 rpm for 3 h. After filtration, the mixture was washed three times with anhydrous ethanol and dried at 55°C and 15 kPa for 18 h to obtain modified glass fiber. 10 g of modified glass fiber and 18 g of modified aluminum hydroxide were added to 450 g of DMF and stirred at 1200 rpm for 30 min. 0.25 g of DMAP was added and the mixture was stirred at 180 rpm for 5 h. 0.25 g of MEA was added and the mixture was stirred at 400 rpm for 30 min. After filtration, the mixture was washed twice with DMF and twice with anhydrous ethanol and dried at 55°C and 12 kPa for 11 h to obtain microparticles.
[0049] 9g of microparticles were mixed with 88g of M n 2000 g / mol of polycaprolactone diol was mixed, heated to 85°C, stirred at 1000 rpm for 30 min, cooled to 50°C, and 16 g of MDI was added under nitrogen protection. The mixture was stirred at 400 rpm for 1 h, and 2.5 g of BDO was added. The mixture was heated to 82°C and stirred at 400 rpm for 1 h. The mixture was poured into a mold and allowed to stand at 45°C and 15 kPa for 22 h. The mixture was then fed into a pulverizer to be pulverized. The fragments were fed into an extruder and extruded at 187°C and a screw speed of 250 rpm. The extrudate was air-cooled and pelletized to obtain masterbatch.
[0050] The mixture consisted of 22g masterbatch, 58g EVA (MFR=1.8g / 10min), 11g EVA-g-MAH, 0.6g antioxidant 1010, and 1.3g M... n 1500 g / mol polyethylene wax was added to a high-speed mixer and stirred at 1000 rpm for 10 min to obtain a high-strength fireproof sheath material for cables.
[0051] The present invention also includes comparative examples and related experiments.
[0052] Comparative Example 1
[0053] The difference between this comparative example and Example 6 is that the aluminum hydroxide was not treated with GPTS hydrolysate. The remaining operation steps and reaction conditions are the same as in Example 6, resulting in a high-strength fireproof sheath material for cables.
[0054] Comparative Example 2
[0055] The difference between this comparative example and Example 6 is that the glass fiber was not treated with GPTS hydrolysate. The remaining operation steps and reaction conditions are the same as in Example 6, resulting in a high-strength fireproof sheath material for cables.
[0056] Comparative Example 3
[0057] The difference between this comparative example and Example 6 is that MEA was not added during the preparation of the microparticles, while the remaining operation steps and reaction conditions were the same as in Example 6, resulting in a high-strength fireproof sheath material for cables.
[0058] Comparative Example 4
[0059] The difference between this comparative example and Example 6 is that the enzymatic hydrolysis of lignin is replaced with bisphenol A (2,2-bis(4-hydroxyphenyl)propane), while the remaining operation steps and reaction conditions are the same as in Example 6, resulting in a high-strength fireproof sheath material for cables.
[0060] Material property testing
[0061] Experimental preparation
[0062] The high-strength fireproof sheath materials for cables prepared in each embodiment and comparative example were mixed in the corresponding proportions and then fed into a flat vulcanizing machine. They were hot-pressed at 175°C and 10MPa for 10 minutes, cooled to room temperature, and then demolded to obtain a plate with a thickness of 1mm. This plate was used to simulate the material properties of the outer sheath of the cable prepared by the same formula through an extrusion process.
[0063] Flame retardancy test
[0064] According to the IEC 60695-11-10 standard, the flame retardancy rating of each board was tested using a UL94 flammability tester, and the results are shown in Table 1.
[0065] Table 1
[0066]
[0067] Tensile property test
[0068] The tensile strength and elongation at break of each sheet were tested according to the IEC60811-501 standard, and the results are shown in Table 2.
[0069] Table 2
[0070]
[0071] Bending fatigue performance test
[0072] Each sheet was cut into strips 1cm wide and 15cm long. Each strip was fixed on a bending tester. The bending radius was set to 5mm, the bending angle to ±90°, and the frequency to 30 cycles / min. The bending axis was perpendicular to the length of the sample. The machine was stopped every 500 cycles. The bending area was checked for cracks with a magnifying glass. The number of cycles at which a through crack first appeared or the sheet completely broke was recorded as the bending fatigue life of the sheet. The results are shown in Table 3.
[0073] Table 3
[0074]
[0075] As shown in Tables 1, 2, and 3, the flame retardancy, tensile strength, and flexural fatigue life of the board prepared in Example 6 are superior to those of Comparative Example 1. This indicates that treating aluminum hydroxide with GPTS hydrolysate is beneficial for coating the aluminum hydroxide surface with enzymatically hydrolyzed lignin, improving the dispersion of microparticles in the polymer matrix, and forming an effective stress transfer and buffering system. This improves the tensile strength and flexural fatigue resistance while meeting the fire retardancy requirements of the sheath. The flexural fatigue life of the board prepared in Example 6 is greater than that of Comparative Example 2, indicating that treating glass fiber with GPTS hydrolysate helps reduce the direct contact area between the modified glass fiber and the polymer matrix, mitigating the impact of glass fiber addition on the flexural fatigue resistance of the sheath. The tensile strength of the board prepared in Example 6 is superior to that of Comparative Example 3, indicating that the addition of MEA can improve the interfacial bonding strength between microparticles and the polymer matrix, thereby enhancing the tensile strength of the sheath. The flexural fatigue life of the board prepared in Example 6 is superior to that of Comparative Example 4, indicating that enzymatically hydrolyzed lignin can effectively mitigate the modulus abrupt change between microparticles and the polymer matrix, prevent stress concentration, and improve the flexural fatigue resistance of the sheath.
Claims
1. A manufacturing process for a high-strength fire-resistant sheath material for cables, characterized in that, Includes the following steps: S1. Modified aluminum hydroxide was obtained by treating aluminum hydroxide with GPTS hydrolysate and enzymatic hydrolysis of lignin. Glass fibers were treated with GPTS hydrolysate to obtain modified glass fibers; modified aluminum hydroxide and modified glass fibers were dispersed in DMF, a nucleophilic catalyst was added for reaction, MEA was added for reaction, and after washing and drying, microparticles were obtained. Modified aluminum hydroxide is prepared by the following method: aluminum hydroxide is dispersed in GPTS hydrolysate for reaction treatment, filtered, washed and then dispersed in DMSO, enzymatically hydrolyzed lignin is added and mixed, triethylamine is added after heating and reaction treatment is carried out, and modified aluminum hydroxide is obtained after filtration, washing and drying. S2. Disperse the microparticles in polycaprolactone diol, add MDI to react, add BDO to react, let stand to solidify, pulverize and granulate to obtain masterbatch; S3. Mix the masterbatch, EVA, EVA-g-MAH, antioxidant, and lubricant to obtain a high-strength fireproof sheath material for cables.
2. The preparation process of a high-strength fire-resistant sheath material for cables according to claim 1, characterized in that, The GPTS hydrolysate is prepared by mixing GPTS and 90-92 wt% ethanol solution, adding acetic acid solution dropwise to adjust the pH to 4-5, and reacting for 1-2 hours to obtain the GPTS hydrolysate.
3. The preparation process of a high-strength fire-resistant sheath material for cables according to claim 2, characterized in that, The aluminum hydroxide was dispersed in GPTS hydrolysate, heated to 55-65℃ and reacted for 2-3 hours. After filtration, the mixture was washed with deionized water, anhydrous ethanol, and DMSO, then dispersed in DMSO. Enzymatically hydrolyzed lignin was added and mixed well. The mixture was heated to 78-82℃, and triethylamine was added and reacted for 2-3 hours. After filtration and washing with anhydrous ethanol, the mixture was dried in an environment of 50-60℃ and 10-20 kPa for 20-24 hours to obtain modified aluminum hydroxide.
4. The preparation process of a high-strength fire-resistant sheath material for cables according to claim 2, characterized in that, The modified glass fiber is prepared by dispersing glass fiber in GPTS hydrolysate, stirring at 300-400 rpm for 3-4 hours, filtering, washing with anhydrous ethanol, and drying in an environment of 50-60°C and 10-20 kPa for 18-22 hours to obtain the modified glass fiber.
5. The preparation process of a high-strength fire-resistant sheath material for cables according to claim 1, characterized in that, In step S1, modified glass fiber and modified aluminum hydroxide are dispersed in DMF, and the nucleophilic catalyst DMAP is added and reacted for 5-6 hours. MEA is added and reacted for 30-50 minutes. After filtration, the mixture is washed with DMF and anhydrous ethanol and then dried in an environment of 50-60°C and 10-15 kPa for 10-12 hours to obtain microparticles.
6. The preparation process of a high-strength fire-resistant sheath material for cables according to claim 1, characterized in that, In step S2, the microparticles are dispersed in polycaprolactone diol at 80-85℃, cooled to 50-60℃, and MDI is added under an inert atmosphere and reacted for 1-2 hours. BDO is then added, and the mixture is heated to 78-82℃ and reacted for 1-2 hours. The mixture is then allowed to stand for 20-24 hours at 40-50℃ and 10-20 kPa. After pulverization, the mixture is fed into an extruder for extrusion at a temperature of 185-190℃ and a screw speed of 200-250 rpm. The extrudate is then air-cooled and pelletized to obtain masterbatch.
7. A high-strength fire-resistant sheath material for cables, characterized in that, The raw materials include the following parts by weight: 18-22 parts masterbatch, 58-64 parts EVA, 9-12 parts EVA-g-MAH, 0.4-0.6 parts antioxidant 1010, and 1.3-1.6 parts lubricant polyethylene wax; the masterbatch includes the following parts by weight: 9-12 parts microparticles, 88-93 parts polycaprolactone diol, 14-16 parts MDI, and 2.3-2.9 parts BDO; The microparticles comprise the following raw materials in parts by weight: 9-12 parts modified glass fiber, 18-21 parts modified aluminum hydroxide, 0.2-0.3 parts DMAP, and 0.2-0.3 parts MEA; the modified aluminum hydroxide comprises the following raw materials in parts by weight: 17-21 parts aluminum hydroxide, 210-220 parts GPTS hydrolysate, 9-12 parts enzymatically hydrolyzed lignin, and 0.1-0.2 parts triethylamine; the modified glass fiber comprises the following raw materials in parts by weight: 20-23 parts glass fiber and 250-260 parts GPTS hydrolysate.
8. A high-strength fire-resistant sheath material for cables according to claim 7, characterized in that, The GPTS hydrolysate comprises the following raw materials in parts by weight: 15-18 parts by weight of GPTS and 570-580 parts by weight of 90-92 wt% ethanol solution.