High-strength composite silicon core pipe and preparation method thereof

Abstract

The invention relates to the technical field of silicon core pipes, and discloses a high-strength composite silicon core pipe and a preparation method thereof.The silicon core pipe comprises an inner layer and an outer layer, and the inner layer comprises 70-80 parts of high-density polyethylene, 15-25 parts of polyurethane, 3-5 parts of filler, 6-10 parts of flame retardant, 6-12 parts of polydimethylsiloxane, 1-2 parts of antioxidant, 1-2 parts of silicon dioxide powder and 2-4 parts of polyisoprene; the outer layer is prepared from 70 to 80 parts of high-density polyethylene, 20 to 30 parts of polyurethane, 10 to 20 parts of filler, 3 to 5 parts of flame retardant, 2 to 4 parts of antioxidant, 2 to 4 parts of silicon dioxide powder and 4 to 8 parts of polyisoprene; the preparation method comprises the following steps: heating and melting an inner-layer raw material to obtain an inner-layer molten liquid; heating and melting the outer-layer raw material to obtain an outer-layer molten liquid; and then synchronously extruding and compounding the inner-layer molten liquid and the outer-layer molten liquid, and molding. According to the scheme of adding the silicon dioxide powder and the polyisoprene into the raw materials, the compressive strength of the silicon core pipe is improved through the synergistic effect, and the cost is lower.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon core tubes, and in particular relates to a high-strength composite silicon core tube and a preparation method thereof. Background Art

[0002] Silicone-core pipe is a composite pipe material with a silicone lubricant applied to the inner wall. Produced by simultaneous extrusion and compounding in a plastic extruder, the pipe features a high-density polyethylene outer layer and a silicone plastic inner layer. Silicone-core pipe is primarily used for protecting and laying cables in communications and power systems. The smooth inner layer reduces friction during cable insertion and is widely used in long-distance fiber optic cable laying and oilfield pipelines.

[0003] Compared with metal pipes (such as steel pipes), although silicon-core pipes have anti-corrosion functions, their compressive resistance is relatively weak. If the backfill soil is not compacted properly or is squeezed by external forces when buried, they are prone to deformation or even rupture. In order to improve the compressive strength of silicon-core pipes, the commonly used method is generally to modify the raw material of silicon-core pipes, high-density polyethylene, to improve the compressive strength of its main raw material, thereby improving the compressive strength of the entire silicon-core pipe. Although the compressive strength of silicon-core pipes can be improved by modifying the raw materials to meet the use under certain special conditions; however, the current silicon-core pipes are expensive because they require the use of more expensive silicone materials and multi-layer co-extrusion technology. If the compressive strength is further improved by modifying the raw materials, the cost of the silicon-core pipe will further increase. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a high-strength composite silicon core tube and a preparation method thereof. By adding silica powder and polyisoprene to the raw materials, the compressive strength of the silicon core tube is synergistically improved, avoiding the problem of increased costs caused by the use of polymer modification.

[0005] The present invention solves the above technical problems through the following technical means:

[0006] In a first aspect, the present invention discloses a high-strength composite silicon core tube, comprising an inner layer and an outer layer formed by double-layer synchronous co-extrusion,

[0007] The inner layer comprises the following raw materials in parts by mass: 70-80 parts of high-density polyethylene, 15-25 parts of polyurethane, 3-5 parts of filler, 6-10 parts of flame retardant, 6-12 parts of polydimethylsiloxane, 1-2 parts of antioxidant, 1-2 parts of silicon dioxide powder, and 2-4 parts of polyisoprene;

[0008] The outer layer comprises the following raw materials in parts by mass: 70-80 parts of high-density polyethylene, 20-30 parts of polyurethane, 10-20 parts of filler, 3-5 parts of flame retardant, 2-4 parts of antioxidant, 2-4 parts of silicon dioxide powder, and 4-8 parts of polyisoprene.

[0009] Furthermore, the raw materials of the inner layer are, by mass, 75 parts of high-density polyethylene, 20 parts of polyurethane, 4 parts of filler, 8 parts of flame retardant, 9 parts of polydimethylsiloxane, 1.5 parts of antioxidant, 1.5 parts of silica powder, and 3 parts of polyisoprene.

[0010] Furthermore, the raw materials of the outer layer are, by mass, 75 parts of high-density polyethylene, 25 parts of polyurethane, 15 parts of filler, 4 parts of flame retardant, 3 parts of antioxidant, 3 parts of silicon dioxide powder, and 6 parts of polyisoprene.

[0011] Furthermore, the filler comprises one or more of glass fiber, carbon fiber, basalt fiber and nano calcium carbonate in any proportion. In this technical solution, the addition of these fillers can improve the compressive and tensile strength of the silicon core tube and inhibit deformation of the silicon core tube after being buried underground.

[0012] Furthermore, the flame retardant includes red phosphorus and melamine, with the mass ratio of red phosphorus to melamine being (1-2):(8:9). In this flame retardant, red phosphorus generates P2O5 upon heating, promoting carbonization and isolating oxygen; melamine decomposes at high temperatures, absorbing heat and releasing nitrogen to dilute oxygen. Therefore, red phosphorus and melamine can synergistically enhance the flame retardancy of the silicon-core tube.

[0013] Furthermore, the antioxidant includes one of antioxidant 1076 and antioxidant 168 or a combination of the two in any proportion.

[0014] Furthermore, the particle size of the silicon dioxide powder is 100-500 nm.

[0015] In a second aspect, the present invention further discloses a method for preparing a high-strength composite silicon core tube, comprising the following steps:

[0016] The inner layer raw material is heated and melted to obtain an inner layer molten liquid; the outer layer raw material is heated and melted to obtain an outer layer molten liquid; then the inner layer molten liquid and the outer layer molten liquid are extruded and compounded synchronously to form a silicon core tube.

[0017] Furthermore, after heating and melting the inner layer raw materials to obtain an inner layer melt, the steps include: heating polyurethane and high-density polyethylene to 180-200° C., completely melting and mixing them uniformly, adding filler, flame retardant, polydimethylsiloxane, antioxidant, silicon dioxide powder and polyisoprene to the mixed melt under stirring, stirring uniformly, and then dispersing them by ultrasonic vibration at 180-190° C. for 10-20 minutes;

[0018] The outer layer raw materials are heated and melted to obtain an outer layer melt, and the steps include: heating polyurethane and high-density polyethylene to 180-200° C., completely melting and mixing them evenly, adding filler, flame retardant, antioxidant, silicon dioxide powder and polyisoprene to the mixed melt under stirring, stirring evenly, and then dispersing them by ultrasonic vibration at 180-190° C. for 10-20 minutes.

[0019] Furthermore, the temperature of the head during the synchronous extrusion of the two layers is 180-190° C., and the frequency during the ultrasonic oscillation dispersion is 80-100 KHz.

[0020] In summary, this application has the following beneficial effects:

[0021] 1. The silicon core tube of the present invention includes an inner layer and an outer layer, and its main raw materials include high-density polyethylene and polyurethane. The addition of flame retardant can effectively resist external combustion when the cable in the silicon core tube burns; the addition of antioxidant can effectively prevent the silicon core tube from being rapidly oxidized during production and use, thereby improving the service life of the silicon core tube; the addition of fillers such as glass fiber, carbon fiber, basalt fiber and nano-calcium carbonate can improve the mechanical properties of the silicon core tube, such as compressive strength, tensile strength, etc.

[0022] 2. The addition of silica powder and polyisoprene to the raw materials of the silicon-core tube of the present invention can make the silica powder and polyisoprene produce a synergistic effect to form a three-dimensional network structure, which can make the molecular chains of high-density polyethylene, polyurethane and other polymer materials interspersed with the three-dimensional network structure formed by silica powder and polyisoprene, thereby improving the rigidity of high-density polyethylene, polyurethane and other polymer materials, and then improving the compressive strength of the silicon-core tube; in this way, the problem of increased cost caused by polymer modification is avoided.

[0023] 3. When preparing the silicon core tube of the present invention, the inner layer raw material melt and the outer layer raw material melt are ultrasonically dispersed respectively. Such operation can further improve the interpenetration rate of the molecular chain and three-dimensional network structure of high-density polyethylene, polyurethane and other polymer materials, and can further improve the compressive strength of the silicon core tube. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] In the following examples, the high-density polyethylene is HDPE 5000S produced by Yanshan Petrochemical, the polyurethane is TPUR 90A produced by Wanhua Chemical, the polydimethylsiloxane is DJ-501 produced by Dongjue Group, and the polyisoprene is Yanshan IP201 produced by Yanshan Petrochemical.

[0026] Example 1

[0027] This embodiment is a first method for preparing a high-strength composite silicon core tube, comprising the following steps:

[0028] The inner layer raw material is heated and melted to obtain an inner layer molten liquid; the outer layer raw material is heated and melted to obtain an outer layer molten liquid; the inner layer molten liquid and the outer layer molten liquid are then extruded and compounded simultaneously, and the temperature of the head during the simultaneous extrusion of the two layers is 180°C, and the silicon core tube is formed.

[0029] Among them, after the inner layer raw materials are heated and melted, an inner layer melt is obtained, and the steps include: heating 15kg of polyurethane and 70kg of high-density polyethylene to 180°C, completely melting and mixing them evenly, adding 3kg of filler, 6kg of flame retardant, 6kg of polydimethylsiloxane, 1kg of antioxidant, 1kg of silica powder and 2kg of polyisoprene to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 180°C for 10 minutes, and the frequency of ultrasonic oscillation dispersion is 80KHz; after the outer layer raw materials are heated and melted, an outer layer melt is obtained, and the steps include: heating 20kg of polyurethane and 70kg of high-density polyethylene to 180°C, completely melting and mixing them evenly, and adding 10kg of filler, 3kg of flame retardant, 2kg of antioxidant, 2kg of silica powder and 4kg of polyisoprene to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 180°C for 10 minutes; the frequency of ultrasonic oscillation dispersion is 80KHz.

[0030] In this embodiment, the filler is glass fiber. The flame retardant includes red phosphorus and melamine, with the mass ratio of red phosphorus to melamine being 1:9. The antioxidant is antioxidant 1076. The particle size of the silicon dioxide powder is approximately 100 nm.

[0031] Example 2

[0032] This embodiment is a second method for preparing a high-strength composite silicon core tube, comprising the following steps:

[0033] The inner layer raw material is heated and melted to obtain an inner layer molten liquid; the outer layer raw material is heated and melted to obtain an outer layer molten liquid; then the inner layer molten liquid and the outer layer molten liquid are extruded and compounded simultaneously, and the temperature of the head during the simultaneous extrusion of the two layers is 185°C, and the silicon core tube is formed.

[0034] Among them, after the inner layer raw materials are heated and melted, the inner layer melt is obtained, and the steps include: heating 20kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, adding 4kg of filler, 8kg of flame retardant, 9kg of polydimethylsiloxane, 1.5kg of antioxidant, 1.5kg of silica powder and 3kg of polyisoprene to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 185°C for 15 minutes, and the frequency of ultrasonic oscillation dispersion is 90KHz; after the outer layer raw materials are heated and melted, the outer layer melt is obtained, and the steps include: heating 25kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, and adding 15kg of filler, 4kg of flame retardant, 3kg of antioxidant, 3kg of silica powder and 6kg of polyisoprene to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 185°C for 15 minutes; the frequency of ultrasonic oscillation dispersion is 90KHz.

[0035] In this embodiment, the filler is carbon fiber. The flame retardant includes red phosphorus and melamine, with the mass ratio of red phosphorus to melamine being 2:9. The antioxidant is antioxidant 168. The particle size of the silica powder is approximately 300 nm.

[0036] Example 3

[0037] This embodiment is a third method for preparing a high-strength composite silicon core tube, comprising the following steps:

[0038] The inner layer raw material is heated and melted to obtain an inner layer molten liquid; the outer layer raw material is heated and melted to obtain an outer layer molten liquid; then the inner layer molten liquid and the outer layer molten liquid are extruded and compounded simultaneously, and the temperature of the head during the simultaneous extrusion of the two layers is 190°C, and the silicon core tube is formed.

[0039] Among them, after the inner layer raw materials are heated and melted, an inner layer melt is obtained, and the steps include: heating 25kg of polyurethane and 80kg of high-density polyethylene to 200°C, completely melting and mixing them evenly, adding 5kg of filler, 10kg of flame retardant, 12kg of polydimethylsiloxane, 2kg of antioxidant, 2kg of silica powder and 4kg of polyisoprene to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 190°C for 20 minutes, and the frequency of ultrasonic oscillation dispersion is 100KHz; after the outer layer raw materials are heated and melted, an outer layer melt is obtained, and the steps include: heating 30kg of polyurethane and 80kg of high-density polyethylene to 200°C, completely melting and mixing them evenly, and adding 20kg of filler, 5kg of flame retardant, 4kg of antioxidant, 4kg of silica powder and 8kg of polyisoprene to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 190°C for 20 minutes; the frequency of ultrasonic oscillation dispersion is 100KHz.

[0040] In this embodiment, the filler is a combination of glass fiber, carbon fiber, basalt fiber, and nano-calcium carbonate in equal weights. The flame retardant is red phosphorus and melamine, with a red phosphorus to melamine ratio of 2:8. The antioxidant is a combination of antioxidant 1076 and antioxidant 168 in equal weights. The silica powder has a particle size of approximately 500 nm.

[0041] Example 4

[0042] This embodiment is a fourth method for preparing a high-strength composite silicon core tube, comprising the following steps:

[0043] The inner layer raw material is heated and melted to obtain an inner layer molten liquid; the outer layer raw material is heated and melted to obtain an outer layer molten liquid; then the inner layer molten liquid and the outer layer molten liquid are extruded and compounded simultaneously, and the temperature of the head during the simultaneous extrusion of the two layers is 185°C, and the silicon core tube is formed.

[0044] Among them, after the inner layer raw materials are heated and melted, the inner layer melt is obtained, and the steps include: heating 20kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, adding 4kg of filler, 8kg of flame retardant, 9kg of polydimethylsiloxane, 1.5kg of antioxidant, 1.5kg of silica powder and 3kg of polyisoprene to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 185°C for 15 minutes, and the frequency of ultrasonic oscillation dispersion is 90KHz; after the outer layer raw materials are heated and melted, the outer layer melt is obtained, and the steps include: heating 25kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, and adding 15kg of filler, 4kg of flame retardant, 3kg of antioxidant, 3kg of silica powder and 6kg of polyisoprene to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 185°C for 15 minutes; the frequency of ultrasonic oscillation dispersion is 90KHz.

[0045] In this embodiment, the filler is basalt fiber. The flame retardant includes red phosphorus and melamine, with the mass ratio of red phosphorus to melamine being 2:9. The antioxidant is antioxidant 168. The particle size of the silica powder is approximately 300 nm.

[0046] Example 5

[0047] This embodiment is a fifth method for preparing a high-strength composite silicon core tube, comprising the following steps:

[0048] The inner layer raw material is heated and melted to obtain an inner layer molten liquid; the outer layer raw material is heated and melted to obtain an outer layer molten liquid; then the inner layer molten liquid and the outer layer molten liquid are extruded and compounded simultaneously, and the temperature of the head during the simultaneous extrusion of the two layers is 185°C, and the silicon core tube is formed.

[0049] Among them, after the inner layer raw materials are heated and melted, the inner layer melt is obtained, and the steps include: heating 20kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, adding 4kg of filler, 8kg of flame retardant, 9kg of polydimethylsiloxane, 1.5kg of antioxidant, 1.5kg of silica powder and 3kg of polyisoprene to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 185°C for 15 minutes, and the frequency of ultrasonic oscillation dispersion is 90KHz; after the outer layer raw materials are heated and melted, the outer layer melt is obtained, and the steps include: heating 25kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, and adding 15kg of filler, 4kg of flame retardant, 3kg of antioxidant, 3kg of silica powder and 6kg of polyisoprene to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 185°C for 15 minutes; the frequency of ultrasonic oscillation dispersion is 90KHz.

[0050] In this embodiment, the filler is nano-calcium carbonate. The flame retardant includes red phosphorus and melamine, with the mass ratio of red phosphorus to melamine being 1:8. The antioxidant is antioxidant 168. The particle size of the silicon dioxide powder is approximately 300 nm.

[0051] Example 6

[0052] The only difference between this embodiment and embodiment 2 is that the inner layer raw material and the outer layer raw material used in this embodiment do not contain silicon dioxide powder.

[0053] The inner layer raw material is heated and melted to obtain an inner layer molten liquid; the outer layer raw material is heated and melted to obtain an outer layer molten liquid; then the inner layer molten liquid and the outer layer molten liquid are extruded and compounded simultaneously, and the temperature of the head during the simultaneous extrusion of the two layers is 185°C, and the silicon core tube is formed.

[0054] Among them, after the inner layer raw materials are heated and melted, an inner layer melt is obtained, and the steps include: heating 20kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, adding 4kg of filler, 8kg of flame retardant, 9kg of polydimethylsiloxane, 1.5kg of antioxidant and 3kg of polyisoprene to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 185°C for 15 minutes, and the frequency of ultrasonic oscillation dispersion is 90KHz; after the outer layer raw materials are heated and melted, an outer layer melt is obtained, and the steps include: heating 25kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, and adding 15kg of filler, 4kg of flame retardant, 3kg of antioxidant and 6kg of polyisoprene to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 185°C for 15 minutes; the frequency of ultrasonic oscillation dispersion is 90KHz.

[0055] In this embodiment, the filler is carbon fiber. The flame retardant includes red phosphorus and melamine, with the mass ratio of red phosphorus to melamine being 2:9. The antioxidant is antioxidant 168.

[0056] Example 7

[0057] The only difference between this embodiment and embodiment 2 is that the inner layer raw material and the outer layer raw material used in this embodiment do not contain polyisoprene. The details are as follows:

[0058] The inner layer raw material is heated and melted to obtain an inner layer molten liquid; the outer layer raw material is heated and melted to obtain an outer layer molten liquid; then the inner layer molten liquid and the outer layer molten liquid are extruded and compounded simultaneously, and the temperature of the head during the simultaneous extrusion of the two layers is 185°C, and the silicon core tube is formed.

[0059] Among them, after the inner layer raw materials are heated and melted, the inner layer melt is obtained, and the steps include: heating 20kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, adding 4kg of filler, 8kg of flame retardant, 9kg of polydimethylsiloxane, 1.5kg of antioxidant, and 1.5kg of silica powder to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 185°C for 15 minutes, and the frequency of ultrasonic oscillation dispersion is 90KHz; after the outer layer raw materials are heated and melted, the outer layer melt is obtained, and the steps include: heating 25kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, and adding 15kg of filler, 4kg of flame retardant, 3kg of antioxidant, and 3kg of silica powder to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 185°C for 15 minutes; the frequency of ultrasonic oscillation dispersion is 90KHz.

[0060] In this embodiment, the filler is carbon fiber. The flame retardant includes red phosphorus and melamine, with the mass ratio of red phosphorus to melamine being 2:9. The antioxidant is antioxidant 168. The particle size of the silica powder is approximately 300 nm.

[0061] Example 8

[0062] The only difference between this embodiment and embodiment 2 is that the inner layer raw material and the outer layer raw material used in this embodiment do not contain polyisoprene and silicon dioxide powder. The details are as follows:

[0063] The inner layer raw material is heated and melted to obtain an inner layer molten liquid; the outer layer raw material is heated and melted to obtain an outer layer molten liquid; then the inner layer molten liquid and the outer layer molten liquid are extruded and compounded simultaneously, and the temperature of the head during the simultaneous extrusion of the two layers is 185°C, and the silicon core tube is formed.

[0064] Among them, after the inner layer raw materials are heated and melted, the inner layer melt is obtained, and the steps include: heating 20kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, adding 4kg of filler, 8kg of flame retardant, 9kg of polydimethylsiloxane, 1.5kg of antioxidant, and 1.5kg of silica powder to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 185°C for 15 minutes, and the frequency of ultrasonic oscillation dispersion is 90KHz; after the outer layer raw materials are heated and melted, the outer layer melt is obtained, and the steps include: heating 25kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, and adding 15kg of filler, 4kg of flame retardant, 3kg of antioxidant, and 3kg of silica powder to the mixed melt under stirring, stirring evenly, and ultrasonically oscillating and dispersing at 185°C for 15 minutes; the frequency of ultrasonic oscillation dispersion is 90KHz.

[0065] In this embodiment, the filler is carbon fiber. The flame retardant includes red phosphorus and melamine, with the mass ratio of red phosphorus to melamine being 2:9. The antioxidant is antioxidant 168.

[0066] Example 9

[0067] The only difference between this embodiment and embodiment 2 is that ultrasonic vibration dispersion is not used in the preparation of the inner layer melt and the outer layer melt.

[0068] The inner layer raw material is heated and melted to obtain an inner layer molten liquid; the outer layer raw material is heated and melted to obtain an outer layer molten liquid; then the inner layer molten liquid and the outer layer molten liquid are extruded and compounded simultaneously, and the temperature of the head during the simultaneous extrusion of the two layers is 185°C, and the silicon core tube is formed.

[0069] Among them, after the inner layer raw materials are heated and melted, an inner layer melt is obtained, and the steps include: heating 20kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, adding 4kg of filler, 8kg of flame retardant, 9kg of polydimethylsiloxane, 1.5kg of antioxidant, 1.5kg of silica powder and 3kg of polyisoprene to the mixed melt under stirring, and stirring them evenly; after the outer layer raw materials are heated and melted, an outer layer melt is obtained, and the steps include: heating 25kg of polyurethane and 75kg of high-density polyethylene to 190°C, completely melting and mixing them evenly, and then adding 15kg of filler, 4kg of flame retardant, 3kg of antioxidant, 3kg of silica powder and 6kg of polyisoprene to the mixed melt under stirring, and stirring them evenly.

[0070] In this embodiment, the filler is carbon fiber. The flame retardant includes red phosphorus and melamine, with the mass ratio of red phosphorus to melamine being 2:9. The antioxidant is antioxidant 168. The particle size of the silica powder is approximately 300 nm.

[0071] The silicon core tubes prepared in Examples 1 to 9 above have the same diameter and the same wall thickness of the outer layer and the inner layer. The silicon core tubes prepared in Examples 1 to 9 are tested for mechanical indicators. The test standards for tensile strength and elongation at break are GB / T 1040.2; the test standard for compressive strength, i.e., ring stiffness, is GB / T 9647; and the test standard for anti-slip performance is GB / T 3694. The results are as follows:

[0072] Example Tensile strength (MPa) Elongation at break (%) <![CDATA[Compressive strength (kN / m 2 )]]> Anti-slip performance Example 1 28.2 615 15.2 0.25 Example 2 29.1 624 15.5 0.24 Example 3 29.2 614 15.6 0.24 Example 4 28.8 606 15.2 0.23 Example 5 28.6 608 15.3 0.25 Example 6 21.8 556 12.6 0.26 Example 7 21.6 568 13.1 0.24 Example 8 20.9 558 12.9 0.26 Example 9 24.5 549 13.9 0.24

[0073] From the comparison between Example 2 and Example 8, it can be seen that after adding silica powder and polyisoprene to the outer layer raw material and the inner layer raw material in the present invention, the tensile strength, elongation at break and compressive strength of the silicon core tube can be greatly improved; and from the comparison between Example 6, Example 7 and Example 8 and Example 2, it can be seen that if only silica powder or polyisoprene is added, the mechanical properties of the silicon core tube cannot be greatly improved, while the combination of silica powder and polyisoprene can greatly improve the mechanical properties of the silicon core tube, indicating that in the preparation of the present silicon core tube, silica powder and polyisoprene produce a synergistic effect, forming a three-dimensional network structure in the silicon core tube, so that the molecular chains of polymer materials such as high-density polyethylene and polyurethane are interspersed with the three-dimensional network structure formed by silica powder and polyisoprene, thereby improving the rigidity of polymer materials such as high-density polyethylene and polyurethane, and then improving the compressive strength of the silicon core tube.

[0074] From the comparison between Example 2 and Example 9, it can be seen that the use of ultrasonic vibration dispersion during the preparation of the inner layer melt and the outer layer melt can further improve the mechanical properties of the silicon-core tube. This shows that when preparing the silicon-core tube of the present invention, ultrasonic vibration dispersion of the inner layer raw material melt and the outer layer raw material melt can further improve the interpenetration rate of the molecular chain and three-dimensional network structure of the polymer material such as high-density polyethylene and polyurethane, and can further improve the compressive strength of the silicon-core tube.

[0075] The above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that the technical solutions of the present invention may be modified or replaced with equivalents without departing from the spirit and scope of the technical solutions of the present invention, and such modifications or equivalents shall be encompassed by the claims of the present invention. Any techniques, shapes, and structures not described in detail herein are well known.

Claims

1. A high-strength composite silicon core tube, comprising an inner layer and an outer layer formed by double-layer synchronous co-extrusion, characterized in that: The inner layer comprises the following raw materials in parts by mass: 70-80 parts of high-density polyethylene, 15-25 parts of polyurethane, 3-5 parts of filler, 6-10 parts of flame retardant, 6-12 parts of polydimethylsiloxane, 1-2 parts of antioxidant, 1-2 parts of silicon dioxide powder, and 2-4 parts of polyisoprene; The outer layer comprises the following raw materials in parts by mass: 70-80 parts of high-density polyethylene, 20-30 parts of polyurethane, 10-20 parts of filler, 3-5 parts of flame retardant, 2-4 parts of antioxidant, 2-4 parts of silicon dioxide powder, and 4-8 parts of polyisoprene.

2. A high-strength composite silicon core tube according to claim 1, characterized in that: In terms of mass, the raw materials of the inner layer are: 75 parts of high-density polyethylene, 20 parts of polyurethane, 4 parts of filler, 8 parts of flame retardant, 9 parts of polydimethylsiloxane, 1.5 parts of antioxidant, 1.5 parts of silicon dioxide powder, and 3 parts of polyisoprene.

3. A high-strength composite silicon core tube according to claim 1 or 2, characterized in that: In terms of mass, the raw materials of the outer layer are: 75 parts of high-density polyethylene, 25 parts of polyurethane, 15 parts of filler, 4 parts of flame retardant, 3 parts of antioxidant, 3 parts of silicon dioxide powder, and 6 parts of polyisoprene.

4. A high-strength composite silicon core tube according to claim 1, characterized in that: The filler includes one or more of glass fiber, carbon fiber, basalt fiber and nano calcium carbonate in any proportion.

5. The high-strength composite silicon core tube according to claim 1, characterized in that: The flame retardant comprises red phosphorus and melamine, and the mass ratio of the red phosphorus to the melamine is (1-2): (8:9).

6. The high-strength composite silicon core tube according to claim 1, characterized in that: The antioxidant includes one of antioxidant 1076 and antioxidant 168 or a combination of the two in any proportion.

7. The high-strength composite silicon core tube according to claim 1, characterized in that: The particle size of the silicon dioxide powder is 100-500 nm.

8. A method for preparing a high-strength composite silicon core tube, characterized in that: The silicon core tube is the silicon core tube according to any one of claims 1 to 7, and the preparation method comprises the following steps: The inner layer raw material is heated and melted to obtain an inner layer molten liquid; the outer layer raw material is heated and melted to obtain an outer layer molten liquid; then the inner layer molten liquid and the outer layer molten liquid are extruded and compounded synchronously to form a silicon core tube.

9. The method for preparing a high-strength composite silicon core tube according to claim 8, characterized in that: The inner layer raw materials are heated and melted to obtain an inner layer melt, comprising the steps of: heating polyurethane and high-density polyethylene to 180-200° C., completely melting and mixing them uniformly, adding filler, flame retardant, polydimethylsiloxane, antioxidant, silicon dioxide powder and polyisoprene to the mixed melt under stirring, stirring uniformly, and then dispersing them by ultrasonic vibration at 180-190° C. for 10-20 minutes; The outer layer raw materials are heated and melted to obtain an outer layer melt, and the steps include: heating polyurethane and high-density polyethylene to 180-200° C., completely melting and mixing them evenly, adding filler, flame retardant, antioxidant, silicon dioxide powder and polyisoprene to the mixed melt under stirring, stirring evenly, and then dispersing them by ultrasonic vibration at 180-190° C. for 10-20 minutes.

10. The method for preparing a high-strength composite silicon core tube according to claim 9, characterized in that: The temperature of the head during the synchronous extrusion of the two layers is 180-190° C., and the frequency during the ultrasonic oscillation dispersion is 80-100 KHz.