A clamping protective rubber for transmission line spacer rods

Abstract

A clamping protective rubber for transmission line spacers is prepared by mixing and vulcanizing the following components in parts by weight: 80-100 parts of EPDM rubber, 1-10 parts of a plasticizer, 0.1-1 parts of sulfur, 3-7 parts of a peroxide vulcanizer, 1-3 parts of an antioxidant, 0.2-1 parts of a vulcanization accelerator, 4-8 parts of an oxide, 0.5-1.5 parts of stearic acid, 60-90 parts of a carbon black filler mixture, 10-25 parts of a flaky filler mixture, and 1-10 parts of a powdered rubber filler. The carbon black filler mixture is a mixture of high-wear-resistant carbon black and semi-reinforcing carbon black in a ratio of 1.5-2.5 parts by weight: 1, and the flaky filler mixture is a mixture of 300-400 mesh flaky fillers, 800-1300 mesh flaky fillers, and 1800-2200 mesh flaky fillers in a ratio of 1-3 parts by weight: 1-3: 1-3. The clamping protection rubber made of it has high mechanical strength and high temperature aging resistance, and has a high grip on the wires. During long-term use, it can prevent the spacer rods and wires from loosening and wearing, ensuring line safety.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber, and in particular relates to a clamping and protective rubber for transmission line spacer bars. Background Art

[0002] Spacers are electrical fittings used to reduce wind vibration or sub-span oscillation in split conductors of power transmission lines. The spacers, through the rubber gripping protection within the clamp, hold the conductors in a compressed state, preventing them from falling off, loosening, and wearing out, thus extending their life and ensuring safe operation of the line.

[0003] Invention patent application CN103665600A discloses a material for a damping spacer rubber part for ultra-high voltage transmission lines and its preparation method. The material is composed of the following components in the following mass percentages: 50-55% EPDM rubber, 27-32% high-wear-resistant carbon black, 5-10% acetylene black, 5-8% cyclohexane oil, 2.5-3.5% zinc oxide, 0.3-0.7% ultraviolet absorber, 1-1.5% dicumyl peroxide, 0.2-0.5% sulfur, etc. Acetylene black is used to improve the conductivity of the rubber part, prevent corona discharge under high-voltage electric fields, and ensure the safety of the conductor. Invention patent application CN106609004A discloses a damping rubber for spacer rods and its preparation method. Its components, by weight, are: 100 parts EPDM rubber, 10-25 parts high-wear-resistant structural carbon black, 25-50 parts semi-reinforcing carbon black, 10-30 parts conductive carbon black, 5-10 parts paraffin oil, 0.5-2.0 parts sulfur, 1.2-2.5 parts accelerator, 5.0-8.0 parts zinc oxide powder, 0.5-1.5 parts stearic acid, etc. It has the characteristics of resistance to low temperature, ozone and natural aging, and its low volume resistivity prevents static electricity accumulation in the spacer rod during operation. Invention patent application CN115785578A discloses rubber for damping spacer rods, which includes, by weight: 70-90 parts of ethylene propylene rubber, 10-30 parts of chlorinated polyethylene, 55-80 parts of carbon black, 5-10 parts of zinc oxide, 1-2 parts of stearic acid, 1-2 parts of antioxidant, 2-5 parts of paraffin oil, 0.5-1 part of accelerator, 3-5 parts of cross-linking agent, 2.5-4 parts of vulcanizing agent, and 0.2-0.5 part of sulfur. The spacer rod rubber has excellent antistatic properties, dynamic damping properties, and ozone resistance.

[0004] In actual operation, due to factors such as breeze vibration, sub-spacing oscillation, and long-term high and low temperature environments, the gripping force of the spacer rod's clamping protective rubber on the conductor is reduced. When the gripping force drops to a certain level, it will cause the spacer rod and the conductor to loosen, wear the conductor, and even cause accidents such as the conductor falling off, affecting the conductor life and safe operation of the line. There are many reasons for the above problems, such as the initial gripping force of the clamping protective rubber on the conductor is not strong enough, the permanent deformation of the rubber under high temperature increases, resulting in a decrease in gripping force, and high-temperature aging of the rubber. The existing technology for clamping protective rubber for spacers mainly involves anti-static properties, damping properties, and ozone resistance. There is an urgent need to develop a clamping protective rubber with high mechanical strength, high-temperature aging resistance, low permanent compression deformation, weather resistance, and other properties, especially a high gripping force on the conductor. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and invent a clamping protective rubber for transmission line spacer rods, which has the properties of high mechanical strength, high temperature aging resistance, low compression permanent deformation, weather resistance, etc., and especially has the characteristics of high gripping force on the conductors, thereby preventing the spacer rods and conductors from loosening and wearing, extending the life of the conductors and ensuring the safety of the line.

[0006] The present invention provides a clamping protective rubber for transmission line spacer rods, wherein the rubber is prepared by mixing and vulcanizing the following components in parts by weight: 80-100 parts of EPDM rubber, 1-10 parts of plasticizer, 0.1-1 part of sulfur, 3-7 parts of peroxide vulcanizer, 1-3 parts of antioxidant, 0.2-1 part of vulcanization accelerator, 4-8 parts of oxide, 0.5-1.5 parts of stearic acid, 60-90 parts of carbon black filler mixture, 10-25 parts of flaky filler mixture and 1-10 parts of powdered rubber filler.

[0007] Preferably, the plasticizer is one or a mixture of two or more of trioctyl trimellitate, naphthenic oil and paraffin oil.

[0008] Preferably, the peroxide curing agent is 2,4-di-tert-butylcumene peroxide.

[0009] Preferably, the antioxidant is one or a mixture of 2,2,4-trimethyl-1,2-dihydroquinoline polymer (antioxidant RD) and 4,4'-di(phenylisopropyl)diphenylamine (antioxidant 445).

[0010] Preferably, the vulcanization accelerator is tetramethylthiuram disulfide (TMTD).

[0011] Preferably, the oxide is zinc oxide or magnesium oxide, or a mixture of the two.

[0012] The carbon black filler mixture is prepared by mixing high-wear-resistant carbon black and semi-reinforcing carbon black in a weight ratio of 1.5 to 2.5:1; preferably, the high-wear-resistant carbon black is N330 carbon black and the semi-reinforcing carbon black is N774 carbon black.

[0013] The flaky filler mixture is prepared by mixing 300-400 mesh flaky fillers, 800-1300 mesh flaky fillers and 1800-2200 mesh flaky fillers in a weight ratio of 1-3:1-3:1-3; preferably, the flaky filler is one or a mixture of two or more of glass flakes, mica or montmorillonite.

[0014] The powdered rubber filler is a cross-linked powdered rubber, preferably a cross-linked powdered nitrile rubber.

[0015] Principle of the Invention: After vulcanization, EPDM rubber has a saturated hydrocarbon chain structure and excellent weather resistance and ozone aging resistance, but it has disadvantages such as low tear strength and large compression set. This invention uses EPDM rubber as a spacer to clamp and protect the rubber substrate. Through the optimization of the vulcanization system and reinforcing filler system, it achieves excellent comprehensive performance. The main principles of the invention are explained as follows:

[0016] (1) The role of a certain proportion of high wear-resistant and semi-reinforced carbon black filler mixture: After repeated research and verification, it was found that high wear-resistant carbon black (such as N330 carbon black) reinforced filled EPDM rubber has good mechanical strength and semi-conductivity (volume resistivity can be 1O 6 Ω·cm order of magnitude); EPDM rubber reinforced with semi-reinforced carbon black (such as N774 carbon black) has the advantages of good high temperature aging resistance and low compression permanent deformation, but its insulation is high and the volume resistivity is as high as 10 14 Ω·cm, which does not meet the resistivity requirement of the spacer rod for the clamping rubber (China Electricity Council Standard T / CEC447-2021 stipulates that the volume resistivity should be 1.1×10 5 ~2×10 7 Ω·cm); when high wear-resistant carbon black and semi-reinforcing carbon black are mixed in a ratio of 1.5 to 2.5:1 and used in the amounts provided in the invention, the prepared EPDM rubber combines the respective advantages of the two carbon black fillers, while having the advantages of high mechanical strength and elongation at break, high temperature aging resistance, low compression set, and semi-conductivity.

[0017] (2) The effect of a mixture of flaky fillers of a certain proportion and different sizes: The gripping force of rubber on the conductor is affected by the surface roughness and compressive stress of the rubber. Although the clamping rubber is prepared by a mold under high temperature and high pressure, the surface roughness is mainly determined by the surface morphology of the mold. The addition of flaky fillers does not change the surface roughness much, but the addition of flaky fillers increases the compressive stress of the clamping rubber (under the same compression deformation conditions), thereby increasing the gripping force of the clamping rubber on the conductor. In addition, flaky fillers can improve the flexibility of the EPDM molecular chain and improve the deformation resistance generated when the rubber part and the conductor slide relative to each other. Furthermore, flaky fillers can reduce the stress relaxation behavior of rubber and help avoid the phenomenon that the gripping force of rubber on the conductor decreases rapidly over time. The mixing and doping of flaky fillers of different mesh sizes forms a layered structure of different sizes, avoiding the uneven mixing with rubber that may be caused by the use of large-sized fillers alone. While ensuring the improvement of grip, it reduces the adverse effect of large-sized fillers on the rubber breaking length rate.

[0018] (3) The role of powdered rubber filler: using cross-linked powdered rubber as elastic cross-linking point to improve the flexibility and stress relaxation behavior of EPDM rubber molecular chain, reduce the permanent compression deformation of the clamping rubber, and ensure long-term grip on the wire.

[0019] Beneficial effects: The clamping protective rubber for transmission line spacers of the present invention has the properties of high mechanical strength, high temperature aging resistance, low compression permanent deformation and weather resistance, and in particular has the characteristic of high gripping force on the conductors, which prevents the spacers and conductors from loosening and wearing during long-term use, thereby extending the life of the conductors and ensuring the safety of the lines. DETAILED DESCRIPTION

[0020] Example 1

[0021] A clamping protective rubber for transmission line spacers is prepared by mixing and vulcanizing the following components in parts by weight: 100 parts of EPDM rubber, 5 parts of trioctyl trimellitate, 0.6 parts of sulfur, 6 parts of 2,4-di-tert-butyl peroxide isopropyl benzene, 2 parts of antioxidant 445, 0.4 parts of TMTD vulcanization accelerator, 5 parts of zinc oxide, 1 part of stearic acid, 70 parts of a carbon black filler mixture, 16 parts of a flaky filler mixture, and 2 parts of cross-linked powdered nitrile rubber.

[0022] The carbon black filler mixture is formed by mixing 50 parts by weight of N330 carbon black and 20 parts by weight of N774 carbon black; the flaky filler mixture is formed by mixing 400 mesh glass flakes, 1250 mesh mica, and 2000 mesh glass flake fillers in a weight ratio of 2:1:1.

[0023] The clamping protection rubber parts are prepared according to the following mixing and vulcanization steps: Step 1, mixing in an internal mixer: except for peroxide vulcanizer and sulfur, the remaining raw materials are put into an internal mixer and mixed at room temperature for 10 minutes; Step 2, adding peroxide vulcanizer and sulfur in an open mill: the rubber material prepared in step 1 is put into an open mill with a roller spacing of 2 mm, and the rubber material is rolled over twice, and peroxide and sulfur are added to the wrap roller. After the materials are added, the rubber material is thinly passed 5 times to prepare a mixed rubber; Step 3, vulcanization: the vulcanization conditions are 170°C for 15 minutes, and after taking out, it is secondary vulcanized in a 170°C oven for 120 minutes.

[0024] Grip strength test: Two semicircular clamping protection rubber parts are embedded in the spacer bar chuck hardware, and the metal cable conductor is inserted into the hollow space of the rubber part. The rubber part is closed, assembled with a pin and locked. The spacer bar grips the conductor in a compressed state through the clamping protection rubber part in the chuck; then the spacer bar hardware is fixed to the fixture of the tensile testing machine, and the fixture at the other end of the tensile testing machine clamps the conductor, and then stretches it. The maximum tension during the stretching process is recorded and expressed as the grip strength value.

[0025] Example 2

[0026] Disclosed is a clamping protective rubber for transmission line spacers. The rubber is prepared by mixing and vulcanizing the following components in parts by weight: 100 parts of EPDM rubber, 5 parts of paraffin oil, 0.5 parts of sulfur, 6 parts of 2,4-di-tert-butyl peroxide isopropyl benzene, 2 parts of antioxidant RD, 0.4 parts of TMTD vulcanization accelerator, 5 parts of zinc oxide, 1 part of stearic acid, 70 parts of a carbon black filler mixture, 15 parts of a flaky filler mixture, and 3 parts of cross-linked powdered nitrile rubber.

[0027] The carbon black filler mixture is formed by mixing 45 parts by weight of N330 carbon black and 25 parts by weight of N774 carbon black; the flaky filler mixture is formed by mixing 400-mesh mica, 1250-mesh montmorillonite, and 2000-mesh glass flake filler in a weight ratio of 1:1:2.

[0028] The mixing and vulcanization steps are the same as those in Example 1.

[0029] Comparative Example 1

[0030] A clamping rubber for a spacer rod is prepared by mixing and vulcanizing the following components in parts by weight: 100 parts of EPDM rubber, 5 parts of trioctyl trimellitate, 0.6 parts of sulfur, 6 parts of 2,4-di-tert-butyl peroxide isopropyl benzene, 2 parts of antioxidant 445, 0.4 parts of TMTD vulcanization accelerator, 5 parts of zinc oxide, 1 part of stearic acid, and 70 parts of N330 carbon black.

[0031] Comparative Example 2

[0032] A clamping protective rubber for a spacer rod is prepared by mixing and vulcanizing the following components in parts by weight: 100 parts of EPDM rubber, 5 parts of trioctyl trimellitate, 0.6 parts of sulfur, 6 parts of 2,4-di-tert-butyl peroxide isopropyl benzene, 2 parts of antioxidant 445, 0.4 parts of TMTD vulcanization accelerator, 5 parts of zinc oxide, 1 part of stearic acid, and 70 parts of N774 carbon black.

[0033] Comparative Example 3

[0034] A clamping protective rubber for a spacer rod is prepared by mixing and vulcanizing the following components in parts by weight: 100 parts of EPDM rubber, 5 parts of trioctyl trimellitate, 0.6 parts of sulfur, 6 parts of 2,4-di-tert-butyl peroxide isopropyl benzene, 2 parts of antioxidant 445, 0.4 parts of TMTD vulcanization accelerator, 5 parts of zinc oxide, 1 part of stearic acid, 50 parts of N330 carbon black, and 20 parts of N774 carbon black.

[0035] Explanation of the formula differences between the comparative examples and the inventive examples: Compared with the inventive examples, the filler in comparative example 1 uses only high-wear-resistant N330 carbon black, the filler in comparative example 2 uses only semi-reinforcing N774 carbon black, and the filler in comparative example 3 uses both high-wear-resistant carbon black and semi-reinforcing carbon black, without adding flaky fillers and powdered rubber fillers.

[0036] The mixing and vulcanization processes of the comparative example and the inventive example are the same.

[0037] Table 2 Test results of high temperature aging resistance, compression permanent deformation and grip strength of the embodiments of the present invention and the comparative examples

[0038]

[0039] As can be seen from the table, the EPDM rubber reinforced with high wear resistance carbon black (Comparative Example 1) has good mechanical strength and semi-conductivity (volume resistivity 2.4×10 6 Ω·cm); semi-reinforced carbon black reinforced EPDM rubber (Comparative Example 2) has the advantages of high temperature aging resistance and low compression permanent deformation, but the volume resistivity is as high as 3.4×10 14 Ω·cm; when high-wear-resistant carbon black and semi-reinforced carbon black are mixed (Comparative Example 3), although they have the advantages of both, the gripping force of the prepared rubber part on the wire is only 2240N; in the embodiment of the present invention, a carbon black filler mixture, a flaky filler mixture, and a powdered rubber filler are simultaneously used. On the basis of maintaining the volume resistivity, aging resistance, and compression permanent set, the gripping force is 4360-4550N, which is more than 80% higher than that of the comparative example.

Claims

1. A clamping protective rubber for transmission line spacers, prepared by mixing and vulcanizing the following components in parts by weight: 80-100 parts of EPDM rubber, 1-10 parts of plasticizer, 0.1-1 parts of sulfur, 3-7 parts of peroxide vulcanizer, 1-3 parts of antioxidant, 0.2-1 parts of vulcanization accelerator, 4-8 parts of oxide, 0.5-1.5 parts of stearic acid, characterized in that There are also 60-90 parts of a carbon black filler mixture, 10-25 parts of a flaky filler mixture and 1-10 parts of a powdered rubber filler; the carbon black filler mixture is formed by mixing high-wear-resistant carbon black and semi-reinforcing carbon black in a weight ratio of 1.5-2.5:1, the high-wear-resistant carbon black is N330 carbon black, and the semi-reinforcing carbon black is N774 carbon black; the flaky filler mixture is formed by mixing 300-400 mesh flaky fillers, 800-1300 mesh flaky fillers and 1800-2200 mesh flaky fillers in a weight ratio of 1-3:1-3:1-3, the flaky fillers are one or a mixture of two or more of glass flakes, mica or montmorillonite; the powdered rubber filler is a cross-linked powdered nitrile rubber.

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