High strength pipe and its use as a building scaffold

Abstract

The application provides a high-strength pipe and application thereof as a building scaffold, and raw materials for preparing the pipe include: 30-50 parts of a polymer, 50-70 parts of fibers, 20-40 parts of fillers, 10-20 parts of a dispersing agent, 3-5 parts of a flame retardant, 2-4 parts of an antioxidant, and 15-20 parts of a curing agent by weight; the polymer is epoxy resin, and the fibers are a combination of polyacrylonitrile fibers, glass fibers and plant fibers; through the combined action of the components, the composite material has high tensile strength and bending strength, good material system compatibility, low density, excellent anti-aging performance, and the prepared pipe has excellent bearing performance, light weight and a long service life.

Description

Technical Field

[0001] This invention relates to the field of C08L63 / 00, and more particularly to a high-strength pipe and its application as a building scaffold. Background Technology

[0002] Construction scaffolding refers to various support structures erected on construction sites to facilitate vertical and horizontal transportation. It serves functions such as safety netting and high-altitude component installation, and is generally used for exterior walls, interior decoration, or high-rise buildings where direct construction is not possible. Construction scaffolding is typically made of wood, metal, or composite materials. Metal scaffolding, such as steel scaffolding, is heavy, difficult to move, and prone to electrical conductivity, making it unsafe. Wooden scaffolding is lightweight but lacks strength, is easily corroded, not fireproof, and has a short lifespan. Composite materials, such as plastic scaffolding, are widely used due to their lightweight, low cost, and corrosion resistance; however, plastic scaffolding is prone to aging and cracking after long-term outdoor use, and its strength is also insufficient.

[0003] Chinese patent CN105647115A discloses a carbon fiber composite material for manufacturing scaffolding. This technology involves injection molding carbon fiber, glass fiber, epoxy resin, and fillers to prepare the scaffolding. However, the wettability between the fibers and fillers and the epoxy resin is poor, leading to air bubbles at the interface and reducing the mechanical strength of the scaffolding. Chinese patent CN212478510U discloses a corrosion-resistant scaffolding for bridge and road engineering. To prevent long-term outdoor corrosion, it applies a PVD composite coating, an aluminum-titanium alloy layer, and a thermoplastic polyester composite layer to the outer surface of the scaffolding. However, since the scaffolding is made of metal and is already heavy, the coating further increases its weight, making it inconvenient for movement, installation, and dismantling.

[0004] Based on this, this application provides a high-strength pipe for building scaffolding, starting from the manufacturing materials. The prepared pipe has high tensile and bending strength, excellent load-bearing performance, good material system compatibility, excellent aging resistance, low density, light weight, and long service life. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention first provides a high-strength pipe.

[0006] Furthermore, the raw materials for preparing the pipe include, by weight, 30-50 parts of polymer, 50-70 parts of fiber, 20-40 parts of filler, 10-20 parts of dispersant, 3-5 parts of flame retardant, 2-4 parts of antioxidant, and 15-20 parts of curing agent.

[0007] Furthermore, the polymer is selected from any one or a combination of several of the following: polypropylene, polyethylene, polystyrene-pentadiene-styrene, polyamide resin, polycarbonate, polytetrafluoroethylene, phenolic resin, silicone resin, urea-formaldehyde resin, and epoxy resin.

[0008] Preferably, the polymer is an epoxy resin.

[0009] Furthermore, the epoxy resin includes, but is not limited to, one or more combinations of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, alicyclic epoxy resin, epoxy resin with terminal functional groups such as amino, hydroxy or thiol groups, aliphatic epoxy resin, and halogenated epoxy resin.

[0010] Furthermore, the epoxy resin is selected from any one or a combination of several of the following: bisphenol A type epoxy resin, bisphenol F type epoxy resin, bis(2,3-epoxycyclopentyl) ether, tetraglycidyl ether tetraphenylethane, N,N-diglycidyl aniline, tetrahydrophthalic acid-diglycidyl ether, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexyl carboxylate, dicyclopentadiene dioxide, trimethylolpropane triglycidyl ether, dodecyl glycidyl ether, and tetradecyl glycidyl ether.

[0011] In a preferred embodiment, the epoxy resin is a bisphenol A type epoxy resin, which may be selected from any one or more of the grades including but not limited to E-44, E51, ATLAC430, and DM411-350.

[0012] Furthermore, the fiber is selected from at least one of carbon fiber, glass fiber, polymer fiber, polyester fiber, plant fiber, and boron fiber.

[0013] Furthermore, the fiber is selected from at least one of aramid fiber, polyester fiber, polyethylene fiber, polypropylene fiber, polyacrylonitrile fiber, nylon fiber, polyimide fiber, glass fiber, and plant fiber.

[0014] In a preferred embodiment, the fiber is a combination of polyacrylonitrile fiber, glass fiber, and plant fiber in a mass ratio of 1:(1-3):(1-2). Polyacrylonitrile fiber is a type of carbon fiber, possessing good elasticity, chemical resistance, and UV resistance; glass fiber is an excellent inorganic non-metallic material with excellent insulation and corrosion resistance, but it is relatively brittle; plant fiber is environmentally friendly, biodegradable, high-strength, and lightweight. This application uses a compound of polyacrylonitrile fiber, glass fiber, and plant fiber, further limiting their length and diameter to ensure uniform distribution within the composite material system. This effectively buffers or eliminates longitudinal and transverse stresses within the pipe, preventing deformation or cracking, and enhancing the pipe's tensile and flexural strength. By adjusting the relative content of the three components, the composite material maintains excellent mechanical strength while also possessing a lighter weight, facilitating processing and use.

[0015] Furthermore, the polyacrylonitrile fiber has a diameter of 3-10 μm and a length of 0.2-1.5 mm.

[0016] Preferably, the polyacrylonitrile fiber has a diameter of 5-7 μm and a length of 0.2-0.6 mm.

[0017] Furthermore, the glass fiber has a diameter of 6-20 μm and a length of 0.05-0.5 mm.

[0018] Preferably, the glass fiber has a diameter of 14-20 μm and a length of 0.05-0.2 mm.

[0019] Preferably, the plant fiber has a diameter of 8-12 μm and a length of 1-2 mm.

[0020] Furthermore, the plant fiber is selected from any one of bamboo fiber, wood fiber, and hemp fiber.

[0021] In a preferred embodiment, the plant fiber is jute fiber.

[0022] Furthermore, the polyacrylonitrile fibers and glass fibers are modified with siloxanes containing cyclic structures and C6-C18 long chains. This application utilizes the reinforcing effect of composite fibers and fillers to improve the mechanical strength of the material. However, there is a large interfacial energy between the fiber and organic system interface, resulting in low compatibility. The pipes prepared from these composite materials may contain residual foaming, leading to a decrease in mechanical strength. This application uses siloxanes to modify carbon fibers and acrylonitrile fibers. Siloxanes themselves have good lubricating properties, which can improve the impact resistance of the pipes. However, if their activity is too high, it will cause a decrease in the hardness of the pipes. Therefore, it is further specified that the siloxane contains cyclic structures and C6-C18 long chains. The conjugation effect between the cyclic structure and the epoxy bonds of the epoxy resin improves the dispersion and wetting of the fibers in the resin and also plays a certain reinforcing role in the composite material. In addition, the combination of C6-C18 long chains adjusts the activity of the siloxane to improve the degree of crosslinking of the system.

[0023] Furthermore, the siloxane with a cyclic structure and a C6-C18 long chain is selected from any one of [8-(epoxypropyloxy)-n-octyl]trimethoxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-(2,3-epoxypropoxy)propyltrihexyloxysilane, and 3-glycidyl etheroxypropylmethyldiethoxysilane.

[0024] Furthermore, the modification method of the polyacrylonitrile fiber and glass fiber is as follows: disperse carbon fiber and polyacrylonitrile fiber in an aqueous solution, adjust the pH to 7.5-9, add a siloxane solution with cyclic structure and C6-C18 long chain, react at 90-100℃ for 1-2 hours, filter and dry.

[0025] Furthermore, the siloxane with cyclic structure and C6-C18 long chain accounts for 40-60% of the total amount of carbon fiber and polyacrylonitrile fiber.

[0026] Furthermore, the plant fiber needs to be modified with a quaternary ammonium salt having at least one C12-C24 alkyl long chain. Plant fibers are more environmentally friendly and lightweight, but due to the large number of alcohol hydroxyl groups on their surface, they are prone to water absorption, which significantly affects the service life of composite pipes. This application uses a quaternary ammonium salt having at least one C12-C24 alkyl long chain to passivate the polar groups on the surface of plant fibers, and its alkyl long chain increases the compatibility of plant fibers with epoxy resin and the hydrophobic properties of plant fibers. In the system, through the intermolecular interaction between siloxanes with cyclic structures and C6-C18 long chains, quaternary ammonium salts having at least one C12-C24 alkyl long chains, and epoxy resin, the tensile strength and hydrophobic properties of the composite material are increased, further improving the service life of the material.

[0027] Furthermore, the quaternary ammonium salt having at least one C12-C24 alkyl long chain is selected from at least one of monododecyltrimethylammonium halide, didodecyldimethylammonium halide, monotetradecyltrimethoxyammonium halide, ditetradecyldimethoxyammonium halide, hexadecyltrimethoxyammonium halide, monooctadecyltrimethoxyammonium halide, and dioctadecyldimethylbenzylammonium halide.

[0028] In a preferred embodiment, the quaternary ammonium salt having at least one C12-C24 alkyl long chain is didodecyl dimethyl ammonium halide.

[0029] Further, the modification method of the plant fiber is as follows: disperse the plant fiber in an aqueous solution, add sodium hydroxide to ensure the pH of the system is 8.5-9.5, heat the reaction at 65-85℃ for 2-4 hours, adjust the pH of the system to neutral using an acidic catalyst, add a quaternary ammonium salt with at least one C12-C24 alkyl long chain and stir for 4-6 hours, filter, wash and dry.

[0030] Furthermore, the quaternary ammonium salt having at least one C12-C24 alkyl long chain accounts for 60-80% of the weight of the plant fiber.

[0031] Furthermore, the filler is selected from at least one of calcium carbonate, zinc oxide, magnesium oxide, titanium oxide, aluminum oxide, aluminum hydroxide, silicon dioxide, diatomaceous earth, barium sulfate, bentonite, and talc.

[0032] Preferably, the filler is a combination of calcium carbonate and barium sulfate in a mass ratio of (1-5):1; more preferably (2-3):1.

[0033] Furthermore, the calcium carbonate and barium sulfate have a particle size of 1250-2300 mesh.

[0034] Furthermore, the dispersant is selected from any one of alkylphenol polyoxyethylene ether, fatty acid salt, fatty acid, paraffin, oxidized paraffin, and polyethylene wax.

[0035] Furthermore, the flame retardant is selected from at least one of nitrogen-based flame retardants, phosphorus-based flame retardants, borate flame retardants, amine flame retardants, and antimony-containing flame retardants.

[0036] Furthermore, the flame retardant is selected from one or more combinations of trimethyl phosphate, triethyl phosphate, tricresyl phosphate, triphenyl phosphate, phosphoramide, melamine pyrophosphate, antimony trioxide, antimony pentoxide, ammonium phenylpropionate, ammonium terephthalate, and zinc borate.

[0037] Preferably, the flame retardant is triphenyl phosphate.

[0038] Furthermore, the antioxidant is a combination of thioester antioxidants and hindered phenolic antioxidants in a mass ratio of (0.5-2):1.

[0039] Furthermore, the thioester antioxidant is selected from any one of DLTP, DSTP, and DMTDP.

[0040] Furthermore, the hindered phenolic antioxidant is selected from antioxidant 1010 or antioxidant 1076.

[0041] Furthermore, the curing agent is an acid anhydride-based curing agent.

[0042] Furthermore, the method for preparing the pipe is as follows:

[0043] S1. Preparation of modified fibers;

[0044] S2. After mixing the raw materials evenly, add them to the extruder, melt extrusion, and injection molding.

[0045] Furthermore, the melt extrusion temperature in step S2 is 120-140℃.

[0046] Secondly, this application also provides the application of the pipe material as building scaffolding.

[0047] Beneficial effects

[0048] 1. This application utilizes the combined reinforcing effect of different fibers and further specifies the size and weight ratio of the fibers, so that the composite material of this application not only has high tensile strength and flexural strength, impact resistance, etc., but also good aging resistance.

[0049] 2. This application modifies fibers to improve their compatibility and dispersibility in the resin system, enabling the fibers to be uniformly dispersed within the system and fully eliminating the stress in the longitudinal and transverse directions of the composite material. In addition, by limiting the modifier to siloxanes with cyclic structures and C6-C18 long chains and quaternary ammonium salts with at least one C12-C24 alkyl long chain, the amount of addition is controlled to regulate the degree of crosslinking inside the composite material, thereby further improving the mechanical properties and aging resistance of the pipes prepared from the composite material.

[0050] 3. By controlling the forces within the system, the composite material of this application also has the characteristics of low density and light weight. The prepared pipes are easy to move and disassemble, and can be used in building materials such as building scaffolding.

[0051] 4. The pipes made from the composite materials of this application also have excellent flame retardant properties, and the flame retardant rating can reach UL-94V0 level. Detailed Implementation

[0052] Example

[0053] Example 1

[0054] This embodiment provides a pipe for building scaffolding. The raw materials for preparing the pipe include, by weight, 40 parts of bisphenol A type epoxy resin (E-44), 65 parts of fiber, 30 parts of filler, 15 parts of aluminum stearate, 4 parts of triphenyl phosphate, 3 parts of antioxidant, and 18 parts of phthalic anhydride.

[0055] The fibers are a combination of polyacrylonitrile fibers, glass fibers, and jute fibers in a mass ratio of 1:2:2. The polyacrylonitrile fibers have a diameter of 5 μm and a length of 0.4 mm and were purchased from Shandong Yitai Engineering Materials Co., Ltd.; the glass fibers have a diameter of 17 μm and a length of 0.1 mm and were purchased from Hebei Dengji Metal Products Co., Ltd.; the jute fibers have a diameter of 10 μm and a length of 2 mm and were purchased from Changzhou Fengrun Special Fiber Co., Ltd. The polyacrylonitrile fibers and glass fibers are modified with 3-(2,3-epoxypropoxy)propyltrimethoxysilane, and the jute fibers are modified with didodecyl dimethyl ammonium halide. The specific modification method is described in the pipe preparation method.

[0056] The filler is a combination of calcium carbonate and barium sulfate in a mass ratio of 2:1. The calcium carbonate has a particle size of 1250 mesh and was purchased from Guangzhou Yifeng Chemical Technology Co., Ltd. The barium sulfate has a particle size of 2000 mesh and was purchased from Guizhou Weihang Mining Co., Ltd., WH-BA380. The antioxidant is DLTP and antioxidant 1010 in a mass ratio of 1:1.

[0057] The method for preparing the pipe is as follows:

[0058] S1. Preparation of modified fibers;

[0059] (1) Modification of polyacrylonitrile fiber and glass fiber: Weigh the corresponding weight parts of carbon fiber and polyacrylonitrile fiber and disperse them in the same weight of aqueous solution. Adjust the pH to 8.0, add 50% of the total weight of carbon fiber and polyacrylonitrile fiber of 3-(2,3-epoxypropoxy)propyltrimethoxysilane solution and react at 95℃ for 2h. After filtration, dry.

[0060] (2) Modification of jute fiber: Weigh the corresponding weight parts of jute fiber and disperse them in the same weight of aqueous solution. Add sodium hydroxide to ensure that the pH of the system is 9.0. Heat the reaction at 80°C for 3 hours. Adjust the pH of the system to 7.0 using hydrochloric acid. Add 70% of the weight of jute fiber of didodecyl dimethyl ammonium halide and stir for 4-6 hours. After filtration, wash and dry.

[0061] S2. After mixing the raw materials evenly, add them to the extruder, melt extrude at 130℃, and then injection mold.

[0062] Example 2

[0063] This embodiment provides a pipe for building scaffolding. The raw materials for preparing the pipe include, by weight, 50 parts of bisphenol A epoxy resin (E-44), 70 parts of fiber, 20 parts of filler, 10 parts of aluminum stearate, 3 parts of triphenyl phosphate, 2 parts of antioxidant, and 20 parts of phthalic anhydride.

[0064] The fibers are a combination of polyacrylonitrile fibers, glass fibers, and jute fibers in a mass ratio of 1:1:2. The polyacrylonitrile fibers have a diameter of 7 μm and a length of 0.6 mm and were purchased from Shandong Yitai Engineering Materials Co., Ltd.; the glass fibers have a diameter of 14 μm and a length of 0.05 mm and were purchased from Hebei Dengji Metal Products Co., Ltd.; the jute fibers have a diameter of 8 μm and a length of 1 mm and were purchased from Changzhou Fengrun Special Fiber Co., Ltd. The polyacrylonitrile fibers and glass fibers are modified with 3-(2,3-epoxypropoxy)propyltrimethoxysilane, and the jute fibers are modified with didodecyl dimethyl ammonium halide. The specific modification method is described in the pipe preparation method.

[0065] The filler is a combination of calcium carbonate and barium sulfate in a mass ratio of 3:1. The calcium carbonate has a particle size of 2000 mesh and was purchased from Guangzhou Yifeng Chemical Technology Co., Ltd. The barium sulfate has a particle size of 2000 mesh and was purchased from Guizhou Weihang Mining Co., Ltd., WH-BA380. The antioxidant is DLTP and antioxidant 1010 in a mass ratio of 1:1.

[0066] The method for preparing the pipe is as follows:

[0067] S1. Preparation of modified fibers;

[0068] (1) Modification of polyacrylonitrile fiber and glass fiber: Weigh the corresponding weight parts of carbon fiber and polyacrylonitrile fiber and disperse them in the same weight of aqueous solution. Adjust the pH to 9.0, add 60% of the total weight of carbon fiber and polyacrylonitrile fiber of 3-(2,3-epoxypropoxy)propyltrimethoxysilane solution and react at 100℃ for 2h. After filtration, dry.

[0069] (2) Modification of jute fiber: Weigh the corresponding weight parts of jute fiber and disperse them in the same weight of aqueous solution. Add sodium hydroxide to ensure that the pH of the system is 9.5. Heat the reaction at 65°C for 4 hours. Adjust the pH of the system to 7.0 using hydrochloric acid. Add 60% of the weight of jute fiber of didodecyl dimethyl ammonium halide and stir for 6 hours. After filtration, wash and dry.

[0070] S2. After mixing the raw materials evenly, add them to the extruder, melt extrude at 120℃, and then injection mold.

[0071] Example 3

[0072] This embodiment provides a pipe for building scaffolding. The raw materials for preparing the pipe include, by weight, 30 parts of bisphenol A epoxy resin (E-44), 50 parts of fiber, 40 parts of filler, 20 parts of aluminum stearate, 5 parts of triphenyl phosphate, 4 parts of antioxidant, and 15 parts of phthalic anhydride.

[0073] The fibers are a combination of polyacrylonitrile fibers, glass fibers, and jute fibers in a mass ratio of 1:3:1. The polyacrylonitrile fibers have a diameter of 5 μm and a length of 0.4 mm and were purchased from Shandong Yitai Engineering Materials Co., Ltd.; the glass fibers have a diameter of 20 μm and a length of 0.2 mm and were purchased from Hebei Dengji Metal Products Co., Ltd.; the jute fibers have a diameter of 12 μm and a length of 2 mm and were purchased from Changzhou Fengrun Special Fiber Co., Ltd. The polyacrylonitrile fibers and glass fibers are modified with 3-(2,3-epoxypropoxy)propyltrimethoxysilane, and the jute fibers are modified with didodecyl dimethyl ammonium halide. The specific modification method is described in the pipe preparation method.

[0074] The filler is a combination of calcium carbonate and barium sulfate in a mass ratio of 2.5:1. The calcium carbonate has a particle size of 1500 mesh and was purchased from Guangzhou Yifeng Chemical Technology Co., Ltd., while the barium sulfate has a particle size of 2000 mesh and was purchased from Guizhou Weihang Mining Co., Ltd., WH-BA380. The antioxidant is DLTP and antioxidant 1010 in a mass ratio of 2:1.

[0075] The method for preparing the pipe is as follows:

[0076] S1. Preparation of modified fibers;

[0077] (1) Modification of polyacrylonitrile fiber and glass fiber: Weigh the corresponding weight parts of carbon fiber and polyacrylonitrile fiber and disperse them in the same weight of aqueous solution. Adjust the pH to 7.5, add 40% of the total weight of carbon fiber and polyacrylonitrile fiber of 3-(2,3-epoxypropoxy)propyltrimethoxysilane solution and react at 95℃ for 1h. After filtration, dry.

[0078] (2) Modification of jute fiber: Weigh the corresponding weight parts of jute fiber and disperse them in the same weight of aqueous solution. Add sodium hydroxide to ensure that the pH of the system is 8.5. Heat the reaction at 85°C for 2 hours. Adjust the pH of the system to 7.0 using hydrochloric acid. Add 80% of the weight of jute fiber of didodecyl dimethyl ammonium halide and stir for 4 hours. After filtration, wash and dry.

[0079] S2. After mixing the raw materials evenly, add them to the extruder, melt extrude at 140℃, and then injection mold.

[0080] Comparative Example 1

[0081] It is basically the same as Example 1, except that the fiber is a combination of polyacrylonitrile fiber, glass fiber and jute fiber in a mass ratio of 1:5:1.

[0082] Comparative Example 2

[0083] It is basically the same as Example 1, except that the glass fiber has a diameter of 35μm and a length of 3mm and was purchased from Hebei Dengji Metal Products Co., Ltd.

[0084] Comparative Example 3

[0085] This is basically the same as Example 1, except that the polyacrylonitrile fiber and glass fiber are modified with 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane; the modification method is the same as in Example 1.

[0086] Comparative Example 4

[0087] It is basically the same as Example 1, except that the jute fiber is used directly without modification.

[0088] Comparative Example 5

[0089] It is basically the same as Example 1, except that the jute fiber is modified with 3-chloro-2-hydroxypropyltrimethylammonium chloride, and the modification method is the same as in Example 1.

[0090] Performance testing methods:

[0091] 1. Tensile strength: Samples were prepared and tested in accordance with the provisions of GB / T1040.2-2006 standard;

[0092] 2. Bending strength: Samples were prepared and tested in accordance with the provisions of GB / T9341-2008 standard;

[0093] 3. Water absorption rate: As specified in ASTM-D-570-98 standard;

[0094] 4. Density: Tested according to the geometric method in GB / T 1463-2005.

[0095] Performance test results:

[0096] The test results are shown in Table 1.

[0097] Table 1

[0098] Sample number <![CDATA[Density g / cm 3 > Tensile strength (MPa) Flexural strength MPa Water absorption rate % Example 1 0.91 82.6 90.5 0.07 Example 2 0.93 78.5 83.2 0.10 Example 3 0.98 75.4 79.0 0.11 Comparative Example 1 1.20 65.1 69.5 0.08 Comparative Example 2 0.92 58.9 61.3 0.10 Comparative Example 3 1.33 53.5 55.2 0.08 Comparative Example 4 1.29 41.4 45.7 0.20 Comparative Example 5 1.22 46.5 52.0 0.18

Claims

1. A high-strength pipe, characterized in that, The raw materials for preparing the pipe include, by weight, 30-50 parts polymer, 50-70 parts fiber, 20-40 parts filler, 10-20 parts dispersant, 3-5 parts flame retardant, 2-4 parts antioxidant, and 15-20 parts curing agent. The fiber is a combination of polyacrylonitrile fiber, glass fiber and plant fiber, and the mass ratio of polyacrylonitrile fiber, glass fiber and plant fiber is 1:(1-3):(1-2). The polyacrylonitrile fibers and glass fibers are modified with siloxanes having cyclic structures and C6-C18 long chains; the plant fibers are modified with quaternary ammonium salts having at least one C12-C24 alkyl long chain. The polymer is epoxy resin.

2. The high-strength pipe according to claim 1, characterized in that, The filler is a combination of calcium carbonate and barium sulfate in a mass ratio of (1-5):

1.

3. The high-strength pipe according to claim 2, characterized in that, The antioxidant is a combination of thioester antioxidants and hindered phenolic antioxidants.

4. The application of high-strength pipes according to any one of claims 1-3 as building scaffolding.