Wear-resistant cable for shield tunneling machine and preparation method of wear-resistant cable

Abstract

The invention relates to the technical field of underground cables, and provides a wear-resistant cable for a shield tunneling machine and a preparation method of the wear-resistant cable. The wear-resistant cable for the shield tunneling machine comprises a conductor, an insulating layer, an armor layer and a sheath layer which are sequentially arranged from inside to outside, and the sheath layer is prepared from the following raw materials in parts by weight: 90-100 parts of polyvinyl chloride, 8-14 parts of chlorinated polyethylene, 8-10 parts of a plasticizer, 9-16 parts of filler, 1-4 parts of a stabilizer, 1-2 parts of an antioxidant, 1-3 parts of a lubricant, 1-3 parts of a compatilizer and 1-2 parts of a vulcanizing agent; the chlorinated polyethylene comprises first chlorinated polyethylene and second chlorinated polyethylene; the Mooney viscosity of the first chlorinated polyethylene is 40-60 under the conditions of ML1 + 4 and 121 DEG C; and the Mooney viscosity of the second chlorinated polyethylene is 70-90 under the conditions of ML1 + 4 and 121 DEG C. According to the technical scheme, the problem of poor impact strength of the wear-resistant cable for the shield tunneling machine in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of underground cables, and in particular to a wear-resistant cable for a shield machine and a preparation method thereof. Background Art

[0002] As the core equipment of modern tunnel construction, the shield machine operates in an extremely complex and harsh environment. The irregular distribution of underground rock strata, high-frequency vibrations during construction, and continuous friction of mechanical components place extremely high demands on the wear resistance of the matching cable sheath layer. However, existing wear-resistant materials are often too rigid, resulting in rapid expansion of surface microcracks during friction, which in turn causes brittle fracture under impact loads, resulting in a contradiction between wear resistance and impact strength, which has become a key bottleneck restricting cable reliability.

[0003] During the tunneling process of a shield machine, cables are constantly moving with the equipment and subject to alternating stresses. Sudden impacts from rock or accidental knocks from mechanical components can cause transient shock loads on the cables. While traditional PVC cable sheathing materials offer some wear resistance, they are susceptible to crack propagation and even breakage under impact loads. This is due to the limited flexibility of the molecular chains in such materials and the lack of effective energy dissipation mechanisms. When impacted, stress cannot be quickly dissipated, leading to localized stress concentrations and subsequent sheath failure. This makes the material's impact resistance insufficient to meet the requirements of long-term, stable operation.

[0004] Therefore, it is of vital importance to develop a wear-resistant cable for shield machines with improved impact strength. Summary of the Invention

[0005] The present invention provides a wear-resistant cable for a shield machine and a preparation method thereof, which solves the problem of poor impact strength of the wear-resistant cable for a shield machine in the related art.

[0006] The technical solutions of the present invention are as follows: The present invention provides a wear-resistant cable for a shield machine, comprising a conductor, an insulation layer, an armor layer, and a sheath layer arranged in sequence from the inside to the outside. The sheath layer comprises the following component raw materials in parts by weight: 90-100 parts of polyvinyl chloride, 8-14 parts of chlorinated polyethylene, 8-10 parts of a plasticizer, 9-16 parts of a filler, 1-4 parts of a stabilizer, 1-2 parts of an antioxidant, 1-3 parts of a lubricant, 1-3 parts of a compatibilizer, and 1-2 parts of a vulcanizing agent. The chlorinated polyethylene includes a first chlorinated polyethylene and a second chlorinated polyethylene; The Mooney viscosity of the first chlorinated polyethylene at ML1+4 and 121° C. is 40-60; The Mooney viscosity of the second chlorinated polyethylene at ML1+4 and 121° C. is 70-90.

[0007] In the wear-resistant cable for a shield machine of the present invention, when a plasticizer is added to the raw material of the sheath layer, the plasticizer can be inserted between the polyvinyl chloride molecular chains, weakening the interaction force between the molecular chains, increasing the flexibility and mobility of the molecular chains, and lowering the glass transition temperature of the polyvinyl chloride, so that the polyvinyl chloride can still maintain good flexibility and plasticity at a lower temperature, facilitating processing and molding, and at the same time enabling the sheath layer to better adapt to the bending and twisting of the cable in actual use.

[0008] In the wear-resistant cable for a shield machine of the present invention, since the raw material polyvinyl chloride of the sheath layer will undergo degradation reactions such as molecular chain breakage due to the action of heat and oxygen during high-temperature processing or long-term use, a stabilizer is added to the raw material of the sheath layer. The stabilizer can capture free radicals, neutralize hydrogen chloride, etc., inhibit the thermal degradation and oxidative degradation of polyvinyl chloride during processing and use, and maintain the stability of material properties.

[0009] In the wear-resistant cable for a shield machine of the present invention, when an antioxidant is added to the raw materials of the sheath layer, the antioxidant can inhibit the oxidation reaction of polyvinyl chloride during processing and use by providing hydrogen atoms, decomposing hydrogen peroxides, etc. When polyvinyl chloride is exposed to oxygen, heat, light, etc. to produce free radicals, the antioxidant can terminate the free radical chain reaction, prevent further oxidation degradation of the molecular chain, and extend the service life of the material.

[0010] In the wear-resistant cable for shield machines of the present invention, when a lubricant is added to the raw materials of the sheath layer, the lubricant can reduce the internal friction between polymer molecules during the polyvinyl chloride processing, improving the material's fluidity. Simultaneously, a lubricating film is formed between the material and the surface of the processing equipment, reducing adhesion between the material and the equipment, making the processing process smoother, improving processing efficiency, and ensuring product quality stability.

[0011] In the wear-resistant cable for a shield machine of the present invention, when a compatibilizer is added to the raw materials of the sheath layer, the compatibilizer can improve the compatibility between polyvinyl chloride and other additives, so that each component is more evenly dispersed in the system, thereby improving the comprehensive performance of the material.

[0012] In the wear-resistant cable for a shield machine of the present invention, when a vulcanizing agent is added to the raw materials of the sheath layer, the vulcanizing agent plays a cross-linking role in the sheath layer, thereby ensuring the strength, hardness, wear resistance and chemical corrosion resistance of the sheath layer.

[0013] As a further technical solution, the mass ratio of the first chlorinated polyethylene to the second chlorinated polyethylene is 7:2-3.

[0014] In the present invention, the mass ratio of the first chlorinated polyethylene to the second chlorinated polyethylene may be 7:2, 7:2.1, 7:2.2, 7:2.3, 7:2.4, 7:2.5, 7:2.6, 7:2.7, 7:2.8, 7:2.9, or 7:3, preferably 7:2 or 7:3.

[0015] In the sheath of the wear-resistant cable for shield machines of this invention, the first chlorinated polyethylene improves the system's flexibility and processing fluidity, while the second chlorinated polyethylene enhances the material's strength and hardness. When the mass ratio is between 7:2 and 3, the two complement each other. The first chlorinated polyethylene imparts a degree of flexibility to the sheath, allowing it to adapt to the bending and twisting of the cable during shield machine operation; the high strength and hardness provided by the second chlorinated polyethylene ensures that the sheath is resistant to deformation and damage caused by external friction and compression. This complementary performance achieves an optimal balance of flexibility, strength, and hardness in the sheath, comprehensively enhancing the cable's adaptability to complex and harsh operating environments. Therefore, a mass ratio of 7:2 to 3 between the first and second chlorinated polyethylenes further improves the impact strength of the wear-resistant cable for shield machines.

[0016] As a further technical solution, the filler includes layered silicate minerals; The layered silicate minerals include one or both of montmorillonite and kaolin.

[0017] In the wear-resistant cable for shield machines of the present invention, when fillers are added to the raw materials of the sheath layer, the barrier effect of the layered structure of the fillers effectively blocks the invasion of corrosive substances, ensuring the stability of the sheath layer in harsh chemical environments. The fillers also enable the cable to maintain stable performance when generating heat during long-term operation, avoiding degradation of material performance due to excessively high temperatures.

[0018] As a further technical solution, the layered silicate mineral is a composite layered silicate mineral; The raw materials of the composite layered silicate mineral include layered silicate mineral and 3-bromopyruvic acid in a mass ratio of 10 to 12:1.

[0019] In the sheath layer of the wear-resistant cable for a shield machine of the present invention, the mass ratio of the layered silicate mineral to 3-bromopyruvic acid can be 10:1, 10.1:1, 10.2:1, 10.3:1, 10.4:1, 10.5:1, 10.6:1, 10.7:1, 10.8:1, 10.9:1, 11:1, 11.1:1, 11.2:1, 11.3:1, 11.4:1, 11.5:1, 11.6:1, 11.7:1, 11.8:1, 11.9:1, and 12:1.

[0020] In the sheath layer of the wear-resistant cable for a shield machine of the present invention, the polyvinyl chloride molecular chain carries highly electronegative chlorine atoms, which increases the attraction between the molecular chains, making it difficult for the inorganic filler to be evenly dispersed in the polyvinyl chloride system. The present invention uses 3-bromopyruvic acid composite layered silicate minerals in the raw materials of the cable sheath layer. The carboxyl groups of 3-bromopyruvic acid interact with the active sites on the surface of the layered silicate mineral and are fixed on the mineral surface, introducing organic functional groups and bromine atoms to the surface of the layered silicate mineral. After using the 3-bromopyruvic acid composite layered silicate mineral, the bromine atoms have strong polarity and interact with the polyvinyl chloride molecules, thereby improving the compatibility of the filler with the polyvinyl chloride matrix. When the cable is subjected to friction, stress can be effectively transferred and dispersed between the two, avoiding stress concentration and wear. Moreover, the composite layered silicate mineral forms a reinforced structure in the polyvinyl chloride matrix, enhancing the material's ability to resist deformation, thereby improving the wear resistance of the sheath layer.

[0021] As a further technical solution, the preparation method of the composite layered silicate mineral comprises the following steps: The layered silicate mineral is added into ethanol, and then 3-bromopyruvic acid is added, followed by stirring, concentrating, and drying to obtain the composite layered silicate mineral.

[0022] As a further technical solution, the mass volume ratio of the layered silicate mineral to the ethanol is 1 g:7~8 mL.

[0023] As a further technical solution, the conductor is made of copper.

[0024] As a further technical solution, the material of the insulating layer is cross-linked polyethylene.

[0025] In the wear-resistant cable for shield machines of the present invention, the material of the insulation layer is cross-linked polyethylene. Cross-linked polyethylene has excellent insulation performance and heat resistance, which ensures the safe and reliable operation of the cable. It can not only effectively prevent current leakage and avoid safety accidents caused by insulation failure, but also maintain stable insulation performance in high temperature environment, reduce the degradation of insulation performance caused by thermal aging, and extend the service life of the cable.

[0026] As a further technical solution, the material of the armor layer is steel strip.

[0027] In the wear-resistant cable for shield machines of the present invention, the armor layer is made of steel belt, which has high strength and hardness. When the cable is subjected to external mechanical forces such as extrusion and collision, the steel belt can withstand the external force by virtue of its own strength, thereby protecting the integrity of the internal structure of the cable and ensuring the normal performance of the cable.

[0028] As a further technical solution, the plasticizer includes one or more of dinonyl phthalate, dibutyl phthalate, and dioctyl terephthalate.

[0029] As a further technical solution, the stabilizer includes one or both of dibutyltin dilaurate and dibutyltin maleate.

[0030] As a further technical solution, the antioxidant includes one or more of antioxidant 245, antioxidant 3114, and antioxidant 626.

[0031] As a further technical solution, the lubricant includes one or both of zinc stearate and calcium stearate.

[0032] As a further technical solution, the compatibilizer includes one or both of maleic anhydride grafted polyethylene and maleic anhydride-styrene copolymer.

[0033] As a further technical solution, the vulcanizing agent includes one or both of dicumyl peroxide and benzoyl peroxide.

[0034] The present invention also proposes a method for preparing a wear-resistant cable for a shield machine, which is used to prepare the wear-resistant cable for a shield machine, comprising the following steps: S1. Extruding the material of the insulating layer outside the conductor to form an insulating layer, and wrapping the material of the armor layer outside the insulating layer to obtain a semi-finished product; S2. Evenly mix the raw materials of the sheath layer, extrude the raw materials onto the semi-finished product, and vulcanize the semi-finished product to obtain the wear-resistant cable for the shield machine.

[0035] The working principle and beneficial effects of the present invention are: In the present invention, a first chlorinated polyethylene (CP) with a Mooney viscosity of 40-60 at ML 1+4 and 121°C and a second chlorinated polyethylene (CP) with a Mooney viscosity of 70-90 at ML 1+4 and 121°C are combined to improve the impact strength of wear-resistant cables for shield machines. Unlike prior art methods that use CPs with moderate Mooney viscosities to improve cable processing performance, such as extrusion and mixing, the present invention recognizes that the Mooney viscosity of CPs at ML 1+4 and 121°C can also affect the material's impact strength. The first CP, with its excellent fluidity and flexibility, can be evenly distributed among other components, such as polyvinyl chloride. When the cable encounters an impact, it can absorb part of the impact force by virtue of its own deformation, effectively alleviating the direct effect of the impact force on the cable. The second chlorinated polyethylene has excellent strength and rigidity due to its high Mooney viscosity. When an impact occurs, it can withstand a large external force to prevent structural damage caused by excessive deformation of the first chlorinated polyethylene. It cooperates with the first chlorinated polyethylene so that the sheath layer can absorb energy through the flexible part under impact and rely on the rigid part to maintain overall stability. The two chlorinated polyethylenes work synergistically to improve the impact strength of the wear-resistant cable for shield machines. DETAILED DESCRIPTION

[0036] 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 any creative efforts are within the scope of protection of the present invention.

[0037] In the following examples and comparative examples, the polyvinyl chloride is of model SG-2; the first chlorinated polyethylene has a Mooney viscosity of 51 at ML 1+4 and 121° C., and the model is CM674, and the Mooney viscosity test method is ASTM D-1646; the second chlorinated polyethylene has a Mooney viscosity of 80 at ML 1+4 and 121° C., and the model is CM3630E, and the Mooney viscosity test method is ASTM D-1646; the maleic anhydride grafted polyethylene is of model OREVAC 18390; the maleic anhydride-styrene copolymer is of model XIRAN 1000; the montmorillonite particle size is 325 mesh, and the kaolin particle size is 325 mesh.

[0038] Example 1 A wear-resistant cable for a shield machine, comprising a copper conductor, an insulation layer, an armor layer, and a sheath layer arranged in sequence from the inside out. The sheath layer comprises the following component raw materials in parts by weight: 100 parts of polyvinyl chloride, 14 parts of chlorinated polyethylene, 5 parts of dinonyl phthalate, 5 parts of dibutyl phthalate, 8 parts of montmorillonite, 8 parts of kaolin, 2 parts of dibutyltin dilaurate, 2 parts of dibutyltin maleate, 1 part of antioxidant 245, 1 part of antioxidant 3114, 1 part of zinc stearate, 2 parts of calcium stearate, 3 parts of maleic anhydride-styrene copolymer, 1 part of dicumyl peroxide, and 1 part of benzoyl peroxide; The chlorinated polyethylene includes a first chlorinated polyethylene and a second chlorinated polyethylene in a mass ratio of 7:5; The preparation method of the wear-resistant cable for a shield machine comprises the following steps: S1. Extruding cross-linked polyethylene (the material of the insulating layer) onto the outside of the copper conductor to form an insulating layer, and wrapping a steel tape (the material of the armor layer) onto the outside of the insulating layer to obtain a semi-finished product; S2. Mix the raw materials of the sheath layer evenly, extrude it onto the semi-finished product, and vulcanize it to obtain a wear-resistant cable for a shield machine.

[0039] Example 2 A wear-resistant cable for a shield machine, comprising a copper conductor, an insulation layer, an armor layer, and a sheath layer arranged in order from the inside out. The sheath layer comprises the following components in parts by weight: 90 parts of polyvinyl chloride, 8 parts of chlorinated polyethylene, 8 parts of dioctyl terephthalate, 9 parts of montmorillonite, 1 part of dibutyltin maleate, 1 part of antioxidant 626, 1 part of calcium stearate, 1 part of maleic anhydride grafted polyethylene, and 1 part of benzoyl peroxide. The chlorinated polyethylene includes a first chlorinated polyethylene and a second chlorinated polyethylene in a mass ratio of 7:1; The preparation method of the wear-resistant cable for a shield machine comprises the following steps: S1. Extruding cross-linked polyethylene (the material of the insulating layer) onto the outside of the copper conductor to form an insulating layer, and wrapping a steel tape (the material of the armor layer) onto the outside of the insulating layer to obtain a semi-finished product; S2. Mix the raw materials of the sheath layer evenly, extrude it onto the semi-finished product, and vulcanize it to obtain a wear-resistant cable for a shield machine.

[0040] Example 3 The only difference between this embodiment and embodiment 2 is that the mass ratio of the first chlorinated polyethylene to the second chlorinated polyethylene in this embodiment is 7:4.

[0041] Example 4 The only difference between this embodiment and embodiment 2 is that the mass ratio of the first chlorinated polyethylene to the second chlorinated polyethylene in this embodiment is 7:2.

[0042] Example 5 The only difference between this embodiment and embodiment 2 is that the mass ratio of the first chlorinated polyethylene to the second chlorinated polyethylene in this embodiment is 7:3.

[0043] Example 6 The only difference between this embodiment and embodiment 5 is that in this embodiment, montmorillonite is replaced by composite montmorillonite of equal mass. The preparation method of the composite montmorillonite includes the following steps: Montmorillonite was added to ethanol, and then 3-bromopyruvic acid was added (the mass ratio of montmorillonite to 3-bromopyruvic acid was 12:1, and the mass volume ratio of montmorillonite to ethanol was 1 g:8 mL), stirred, concentrated, and dried to obtain composite montmorillonite.

[0044] Example 7 The only difference between this embodiment and embodiment 5 is that in this embodiment, montmorillonite is replaced by composite montmorillonite of equal mass. The preparation method of the composite montmorillonite includes the following steps: Montmorillonite was added to ethanol, and then 3-bromopyruvic acid was added (the mass ratio of montmorillonite to 3-bromopyruvic acid was 10:1, and the mass volume ratio of montmorillonite to ethanol was 1 g:7 mL), stirred, concentrated, and dried to obtain composite montmorillonite.

[0045] Comparative Example 1 The only difference between this comparative example and Example 2 is that the chlorinated polyethylene in this comparative example is the first chlorinated polyethylene.

[0046] Comparative Example 2 The only difference between this comparative example and Example 2 is that the chlorinated polyethylene in this comparative example is the second chlorinated polyethylene.

[0047] Comparative Example 3 The only difference between this comparative example and Example 2 is that chlorinated polyethylene is not added in this comparative example.

[0048] Experimental Example 1 The wear-resistant cables for shield machines produced in Examples 1-5 and Comparative Examples 1-3 were tested for notched impact strength according to the test method specified in GB / T 1043.2-2018, "Determination of Impact Properties of Plastics - Part 2: Instrumented Impact Test." Specimen preparation: The cable sheath was cut axially to produce Type 1 specimens, with notch type A and a lateral impact direction at 25°C. The test results are shown in Table 1.

[0049] Table 1 Impact strength test results

[0050] As shown in Table 1, the impact strength of the wear-resistant cables for shield machines prepared in Examples 1 to 5 of the present invention reached 16.2 kJ / m 2 As described above, therefore, in the present invention, the impact strength of the wear-resistant cable for shield machine is improved by adding two types of chlorinated polyethylene with Mooney viscosities.

[0051] Experimental Example 2 The sheath layers of the wear-resistant cables for shield machines prepared in Examples 5 to 7 were tested for mass wear according to the method specified in GB / T 3960-2016, "Test Methods for Sliding Friction and Wear of Plastics." The test results are shown in Table 2.

[0052] Table 2 Mass wear test results

[0053] As shown in Table 2, the mass wear of the sheath layer of the wear-resistant cables prepared in Examples 6 to 7 of the present invention reached less than 29.5 mg. Therefore, in the present invention, the use of 3-bromopyruvic acid composite layered silicate minerals improves the wear resistance of the sheath layer.

[0054] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A wear-resistant cable for a shield machine, characterized in that: The invention comprises a conductor, an insulating layer, an armor layer and a sheath layer arranged in sequence from the inside to the outside, wherein the sheath layer comprises the following components in parts by weight: 90-100 parts of polyvinyl chloride, 8-14 parts of chlorinated polyethylene, 8-10 parts of plasticizer, 9-16 parts of filler, 1-4 parts of stabilizer, 1-2 parts of antioxidant, 1-3 parts of lubricant, 1-3 parts of compatibilizer and 1-2 parts of vulcanizing agent; The chlorinated polyethylene includes a first chlorinated polyethylene and a second chlorinated polyethylene; The Mooney viscosity of the first chlorinated polyethylene at ML1+4 and 121° C. is 40-60; The Mooney viscosity of the second chlorinated polyethylene at ML1+4 and 121° C. is 70-90.

2. A wear-resistant cable for a shield machine according to claim 1, characterized in that: The mass ratio of the first chlorinated polyethylene to the second chlorinated polyethylene is 7:2-3.

3. The wear-resistant cable for a shield machine according to claim 1, characterized in that: The filler includes layered silicate minerals; The layered silicate minerals include one or both of montmorillonite and kaolin.

4. A wear-resistant cable for a shield machine according to claim 3, characterized in that: The layered silicate mineral is a composite layered silicate mineral; The raw materials of the composite layered silicate mineral include layered silicate mineral and 3-bromopyruvic acid in a mass ratio of 10 to 12:

1.

5. The wear-resistant cable for a shield machine according to claim 4, characterized in that: The preparation method of the composite layered silicate mineral comprises the following steps: The layered silicate mineral is added into ethanol, and then 3-bromopyruvic acid is added, followed by stirring, concentrating, and drying to obtain the composite layered silicate mineral.

6. The wear-resistant cable for a shield machine according to claim 1, characterized in that: The material of the conductor is copper.

7. The wear-resistant cable for a shield machine according to claim 1, characterized in that: The material of the insulating layer is cross-linked polyethylene.

8. The wear-resistant cable for a shield machine according to claim 1, characterized in that: The material of the armor layer is steel strip.

9. The wear-resistant cable for a shield machine according to claim 1, characterized in that: The plasticizer includes one or more of dinonyl phthalate, dibutyl phthalate, and dioctyl terephthalate; The stabilizer includes one or both of dibutyltin dilaurate and dibutyltin maleate; The antioxidant includes one or more of antioxidant 245, antioxidant 3114, and antioxidant 626; The lubricant includes one or both of zinc stearate and calcium stearate; The compatibilizer includes one or two of maleic anhydride grafted polyethylene and maleic anhydride-styrene copolymer; The vulcanizing agent includes one or both of dicumyl peroxide and benzoyl peroxide.

10. A method for preparing a wear-resistant cable for a shield machine, for preparing a wear-resistant cable for a shield machine according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Extruding the material of the insulating layer outside the conductor to form an insulating layer, and wrapping the material of the armor layer outside the insulating layer to obtain a semi-finished product; S2. Evenly mix the raw materials of the sheath layer, extrude the raw materials onto the semi-finished product, and vulcanize the semi-finished product to obtain the wear-resistant cable for the shield machine.

Images