Anti-aging flame-retardant cable sheath and preparation method thereof

Abstract

The invention relates to an anti-aging flame-retardant cable sheath and a preparation method thereof. The sheath is one of components of the cable, is mainly made of a high polymer material, and can play a role in insulation and protection. The existing sheath material neglects the problem of degradation of a high polymer material caused by permeation of water, oxygen and other gases into the sheath under natural conditions. The invention discloses a preparation method of a cable sheath. An inner layer of the sheath is mainly composed of crosslinked polyethylene; the outer layer of the cable protection sleeve is a silica gel / graphite skin layer containing molybdenum trioxide. The preparation method comprises the following steps: melting, extruding and forming the crosslinked polyethylene mixed additive to obtain the inner layer; and silicone oil and other additives are mixed and coated on the inner layer. And the inner-layer protective sleeve and the outer-layer protective sleeve are crosslinked together through irradiation to obtain the protective sleeve. Wherein the silica gel has strong hydrophobicity, and can prevent water, oxygen and other gases from permeating into the inner layer of the sheath when being combined with the flake graphite material; molybdenum trioxide can effectively absorb ultraviolet rays. The sheath can be used for protecting outdoor cables.

Description

Technical Field

[0001] The present application relates to the technical field of cable materials, and more specifically, to an aging-resistant and flame-retardant cable protective cover and a preparation method thereof. Background Art

[0002] Cable is a general term for optical cables, electrical cables and other items, which are widely used in power transmission, signal transmission and other occasions. The main components of cables are the wire core and the insulating protective sheath, which is generally made of organic polymer materials such as rubber and polyethylene.

[0003] When cables are used outdoors for a long time, the polymer material in the protective sheath is prone to aging under ultraviolet light, and the water and oxygen in the air that penetrate into the cable sheath will intensify the degradation reaction of the polymer.

[0004] Some existing technologies, such as CN 116589778 B, emphasize the anti-ultraviolet light capability of cables, but ignore the fact that gases such as water and oxygen penetrate into the cable sheath under natural conditions, thereby causing degradation and aging of the sheath.

[0005] In view of the above-mentioned related technologies, the applicant has found that the use of hydrophobic silicone rubber filled with layered graphite material can effectively prevent water and oxygen from penetrating into the polymer material of the sheath, thereby delaying the aging of the sheath; molybdenum trioxide can produce a fluorescent effect when irradiated by ultraviolet rays, and at the same time, carrier recombination can effectively absorb ultraviolet rays and reduce the damage of ultraviolet rays to the polymer material of the sheath. At the same time, silicone rubber and graphite have good flame retardancy and can prevent flames from spreading to the inner layer of the sheath. Molybdenum trioxide can be used as a smoke suppressant to prevent flames from producing thick smoke that is harmful to the human body.

[0006] However, the strength of silicone rubber itself is relatively low, and the cable sheath still needs cross-linked polyethylene as the main force-bearing part. At the same time, silicone rubber with double bonds can undergo a cross-linking reaction with the polyethylene inner sheath layer under the action of radiation, so that the inner and outer sheath layers are tightly combined. Through the combination of the inner and outer sheath layers, the inner layer of cross-linked polyethylene can provide good mechanical strength for the cable, and the outer layer of silicone rubber mixture can effectively block the damage of water, oxygen and ultraviolet rays to the cross-linked polyethylene, thus forming an excellent performance aging-resistant flame-retardant cable. Summary of the invention

[0007] In order to enhance the aging resistance and flame retardancy of cables, the present application provides an aging resistant and flame retardant cable protective cover and a preparation method thereof.

[0008] On the one hand, the present application provides an aging-resistant cable protective cover, which adopts the following technical solution: An aging-resistant and flame-retardant cable sheath, characterized in that: the inner layer of the cable protective sheath is mainly composed of cross-linked polyethylene; the outer layer of the cable protective sheath is a silica gel / graphite cortex, comprising the following raw materials: 100 parts of vinyl silicone oil, 10 parts of hydrogenated silicone oil, 0.2 parts of platinum catalyst, 30-50 parts of expandable graphite, 10 parts of antioxidant, and 2-10 parts of molybdenum trioxide particles.

[0009] The antioxidant is a hindered phenol antioxidant, and the auxiliary material is a phosphite.

[0010] The molybdenum trioxide particles are industrial grade, and the particle size is about 3000 meshes.

[0011] By adopting the above technical solution, the hydrophobic silicone rubber can prevent moisture from gathering on the surface of the material, and the layered graphite stacked together can effectively prevent water and oxygen from penetrating into the polymer material of the sheath, thereby delaying the aging of the sheath; molybdenum trioxide can produce a fluorescent effect when irradiated by ultraviolet rays, and at the same time, carrier recombination can effectively absorb ultraviolet rays and reduce the damage of ultraviolet rays to the polymer material of the sheath. At the same time, silicone rubber and graphite have good flame retardancy and can prevent flames from spreading to the inner layer of the sheath. Molybdenum trioxide can be used as a smoke suppressant to prevent flames from producing thick smoke that harms the human body.

[0012] When the sheath is ignited, the expandable graphite will arch and deform, isolating the flame from the internal polymer material and preventing the flame from spreading further. Silicone rubber itself is not easy to burn. Molybdenum trioxide can inhibit the generation of smoke and prevent the smoke from the flame from causing harm to the human body.

[0013] Preferably, the molybdenum trioxide is a modified molybdenum trioxide that has been surface treated with a vinyl siloxane coupling agent. This can effectively improve the dispersibility of the molybdenum trioxide in the silicone rubber matrix. The vinyl group in the vinyl siloxane coupling agent can undergo an addition reaction with hydrogenated silicone oil under irradiation, thereby anchoring the molybdenum trioxide in the silicone rubber matrix to prevent migration degradation.

[0014] On the other hand, the present application provides a method for preparing an aging-resistant flame-retardant cable sheath, which adopts the following technical solution: A method for preparing an aging-resistant cable protective cover, characterized in that it comprises the following steps: S1. The cross-linked polyethylene material is melt extruded to obtain the inner layer of the sheath; S2. The vinyl silicone oil, expandable graphite, antioxidant, molybdenum trioxide were mixed and ground by a planetary ball mill for 24 hours to obtain a mixture A; S3. Stirring the mixture A obtained by hydrogenated silicone oil, platinum catalyst and S2 to obtain a mixture B; S4. Apply the mixture B obtained in S3 onto the inner layer of the sheath obtained in S1, and cross-link and cure it through radiation to obtain a sheath.

[0015] By adopting the above scheme, the protective sheath is divided into two layers, the inner layer and the outer layer. Using cross-linked polyethylene as the inner layer of the sheath can effectively improve the overall strength of the sheath. At the same time, the silicone rubber with double bonds can undergo a cross-linking reaction with the polyethylene inner sheath layer under the action of radiation, so that the inner and outer sheath layers are tightly combined. Through the combination of the inner and outer sheath layers, the inner layer of cross-linked polyethylene can provide good mechanical strength for the cable, and the outer layer of silicone rubber mixture can effectively block the damage of water, oxygen and ultraviolet rays to the cross-linked polyethylene, thereby jointly forming an excellent performance anti-aging flame-retardant cable sheath. Specific implementation plan

[0016] The present application is further described in detail below with reference to the embodiments.

[0017] raw material The raw materials in the examples of this application can be obtained from commercial sources: The polymer base material of the inner layer is high-density polyethylene with a melt flow rate of 7.25% and a tensile strength of 25MP; Vinyl silicone oil, vinyl mass fraction 0.4%, viscosity 500mPa·s; Hydrogenated silicone oil, active hydrogen mass fraction 0.18%, viscosity 80mPa·s; Platinum catalyst, platinum content 0.5%; Expandable graphite, particle size 250-300μm, expansion rate 150ml / g; Anti-aging agent, a mixture of hindered phenol and phosphite; Molybdenum trioxide, industrial pure, particle size is about 3000 mesh.

[0018] Example Example

[0019] An aging-resistant flame-retardant cable is composed of a wire core wrapped with a sheath. The preparation method of the sheath is as follows: S1. The cross-linked polyethylene material is melt extruded to obtain the inner layer of the sheath; S2. Vinyl silicone oil, expandable graphite, antioxidant, and molybdenum trioxide are mixed according to the raw material ratio in Table 1, and mixed and ground by a planetary ball mill for 24 hours to obtain a mixture A. The particle size of the molybdenum trioxide is about 3000 mesh; S3. Stir the mixture A obtained by mixing the hydrogenated silicone oil and the platinum catalyst according to the raw material ratio in Table 1 with S2 to obtain a mixture B; S4. Apply the mixture B obtained in S3 onto the inner layer of the sheath obtained in S1, and cross-link and cure it through radiation to obtain a sheath.

[0020] Embodiment 2-5 The difference from Example 1 is that the raw material ratio of the aging-resistant cable sheath is different, see Table 1 for details.

[0021] Table 1 Raw material ratio table of Examples 1-5 Example 1 Example 2 Example 3 Example 4 Example 5 Vinyl silicone oil 100 100 100 100 100 Hydrogenated silicone oil 10 10 10 10 10 Platinum catalyst 0.2 0.2 0.2 0.2 0.2 Expandable graphite 40 30 50 40 40 Molybdenum trioxide 6 6 6 2 10 Anti-aging agent 10 10 10 10 10

[0022] Comparative Example

[0023] Comparative Example 1 The difference from Example 1 is that the sheath is only obtained by melt extrusion molding and radiation cross-linking of cross-linked polyethylene.

[0024] Comparative Example 2 Different from Example 1, no expandable graphite is added.

[0025] Comparative Example 3 Different from Example 1, no molybdenum trioxide is added.

[0026] Performance testing Detection method / test method According to the methods described in Examples 1-5 and Comparative Examples 1-3, cables with core wires wrapped in sheaths were manufactured.

[0027] With reference to "General test methods for insulation and sheathing materials for electric and optical cables Part 11: General test methods for thickness and dimensions - Mechanical properties tests" GB / T 2951.11-2008, the tensile strength and elongation at break of the protective sheaths obtained in the examples and comparative examples were tested; With reference to "General test methods for insulation and sheath materials of electrical and optical cables Part 12: General test methods - Thermal aging test methods" GB / T 2951.12-2008, thermal aging tests were performed on the protective covers obtained in the examples and comparative examples.

[0028] The test results are shown in Table 2 Table 2 Performance test results Tensile strength aging retention rate / % Retention rate of breaking strength after aging / % Example 1 97.2 98.1 Example 2 96.3 96.5 Example 3 97.4 98.3 Example 4 95.6 96.1 Example 5 97.3 98.3 Comparative Example 1 81.5 82.4 Comparative Example 2 85.1 87.5 Comparative Example 3 93.4 93.2 Combining Examples 1-5 and Comparative Examples 1-3, it can be seen that the aging resistance of Examples 1-5 is better than that of Comparative Examples 1-3, which indicates that the cable prepared in the present application has better aging resistance.

[0029] Combining Example 1 and Comparative Example 1, it can be seen that the silicone rubber / graphite outer sheath greatly improves the aging resistance of the cable.

[0030] It can be seen from Example 1 and Comparative Example 2 that expandable graphite can effectively prevent water and oxygen from penetrating, and greatly improves the aging resistance of the cable.

[0031] It can be seen from Example 1 and Comparative Example 3 that molybdenum trioxide can effectively absorb and transform ultraviolet light, and greatly improves the aging resistance of the cable.

[0032] It can be seen from Examples 1-3 that the optimum mass fraction of expandable graphite is about 40. When the mass fraction is greater than this, the aging resistance of the cable sheath is slightly improved.

[0033] Combining Example 1 with Examples 4-5, it can be seen that the optimal mass fraction of molybdenum trioxide is about 6. When the mass fraction is greater than this, the aging resistance of the cable sheath is slightly improved.

[0034] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An aging-resistant flame-retardant cable sheath, characterized in that: The inner layer of the cable protective sheath is mainly composed of cross-linked polyethylene; the outer layer of the cable protective sheath is a silicone / graphite cortex, including the following raw materials: 100 parts of vinyl silicone oil, 10 parts of hydrogenated silicone oil, 0.2 parts of platinum catalyst, 30-50 parts of expandable graphite, 10 parts of antioxidant, and 2-10 parts of molybdenum trioxide particles. The antioxidant is a hindered phenol antioxidant, and the auxiliary material is a phosphite. The molybdenum trioxide particles are industrial grade, and the particle size is about 3000 meshes.

2. The aging-resistant cable protective cover according to claim 1, characterized in that: The molybdenum trioxide is modified molybdenum trioxide that has been surface treated with a vinyl siloxane coupling agent.

3. A method for preparing the aging-resistant cable protective cover according to claim 1, characterized in that: The following steps are involved: S1. Melt-extrude the cross-linked polyethylene material to obtain the inner layer of the sheath. S2. Vinyl silicone oil, expandable graphite, antioxidant and molybdenum trioxide are mixed and ground in a planetary ball mill for 24 hours to obtain a mixture A. S3. Stir the hydrogenated silicone oil, the platinum catalyst and the mixture A obtained in S2 to obtain a mixture B. S4. Apply the mixture B obtained in S3 onto the inner layer of the sheath obtained in S1, and cross-link and cure it through radiation to obtain a sheath.