Low-smoke halogen-free cable material for flexible locomotive cable and preparation method of low-smoke halogen-free cable material

Abstract

The invention discloses a low-smoke halogen-free cable material for a flexible locomotive cable and a preparation method of the low-smoke halogen-free cable material. The cable material comprises the following raw materials: 100 parts of a resin material; 130 to 160 parts of a flame retardant; 3-5 parts of an antioxidant; 2-4 parts of a lubricant; 3 parts of a silane coupling agent; 1-3 parts of a crosslinking sensitizer; 3-6 parts of other auxiliary agents; the preparation method comprises the following steps: weighing the raw materials according to the formula proportion, banburying at the banburying temperature of 155 DEG C, fully and uniformly mixing, discharging to a double-screw extruder for mixing, and then feeding into a single-screw extruder for granulating; wherein the temperature of twin-screw extrusion is 120-150 DEG C, the rotating speed frequency of screws is 25 Hz, and the temperature of single-screw extrusion is 80-140 DEG C; and after extrusion, cooling, sieving and drying to obtain the cable material. The cable material provided by the invention has the advantages of environment-friendly and halogen-free formula system, excellent flame retardant property, low material hardness, soft hand feeling, favorable processability and excellent mechanical property, and can meet the EN50264 standard requirement.

Description

Technical Field

[0001] The invention relates to the technical field of cable materials, and in particular to a low-smoke halogen-free cable material for soft locomotive cables and a preparation method thereof. Background Art

[0002] Locomotive cables are an important part of railway locomotives, mainly responsible for transmitting signals, communications, control signals and supplying power; the design and manufacturing technology of locomotive cables are directly related to the safety, reliability and operating efficiency of locomotives. With the development of railway technology, the technology of locomotive cables is also constantly improving to adapt to the operation requirements of higher speeds, longer distances and more complex environments.

[0003] In view of the complex working conditions of locomotive lines, relevant standards have been promulgated at home and abroad to regulate related cable products: such as Europe's EN50264, EN50306 and EN50382 series, China's GB / T12528, TB / T1484, etc. The relevant standards have made requirements on the material's oil resistance, insulation moisture resistance, toxicity index and other indicators, which also put forward strict assessment requirements for the materials; usually, according to the principle of like compatibility, in order to improve the oil resistance of the material, material manufacturers will use EVM rubber with high VA content as the main base material to prepare locomotive cable materials, but there is a problem that when making large-section cables, it is easy to cause adhesion after irradiation, which affects the appearance of the cable.

[0004] Therefore, how to solve the above-mentioned deficiencies in the prior art has become a subject to be studied and solved by the present invention. Summary of the invention

[0005] The object of the present invention is to provide a low-smoke halogen-free cable material for soft locomotive cables and a preparation method thereof.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A low-smoke halogen-free cable material for soft locomotive cables, the raw materials of which include the following components in parts by mass:

[0008] 100 parts of resin material;

[0009] 130-160 parts of flame retardant;

[0010] 3-5 parts of antioxidant;

[0011] 2 to 4 parts of lubricant;

[0012] 1 to 3 parts of silane coupling agent;

[0013] 1 to 3 parts of cross-linking sensitizer;

[0014] 3 to 6 parts of other additives;

[0015] Wherein, the resin material is a combination of one or more of ethylene-vinyl acetate copolymer, polyethylene grafted with maleic anhydride, ethylene-vinyl acetate copolymer grafted with maleic anhydride, ethylene-butyl acrylate copolymer, and polyethylene;

[0016] The antioxidant comprises a primary antioxidant and a secondary antioxidant, wherein the primary antioxidant is a phenolic antioxidant, and the amount of the primary antioxidant is greater than or equal to 50wt% of the total amount of the antioxidant.

[0017] According to a further technical solution, the flame retardant is a combination of one or more of aluminum hydroxide, magnesium hydroxide, and a silicon-based carbon-forming agent, wherein both aluminum hydroxide and magnesium hydroxide have a surface coating agent, and the coating agent is a silane coupling agent, stearic acid, or a water-resistant surface coating agent that the manufacturer is unwilling to disclose.

[0018] In a further technical solution, the main antioxidant is a combination of one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1010), 4,4'-thiobis(6-tert-butyl-3-methylphenol) (antioxidant 300), and 2,2'-thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (antioxidant 1035).

[0019] In a further technical solution, the secondary antioxidant is a combination of one or more of dilauryl thiodipropionate, distearyl thiodipropionate, and high-temperature phosphite.

[0020] According to a further technical solution, the melt index of the ethylene-vinyl acetate copolymer is 1 to 7 g / 10 min, wherein the content of vinyl acetate is 28 to 70 wt %.

[0021] In a further technical solution, the polyethylene has a melt index of 1 to 5 g / 10 min;

[0022] The melt index of the ethylene-butyl acrylate copolymer is 1-5 g / 10 min, wherein the butyl acrylate content is 20-40 wt %.

[0023] According to a further technical solution, in the ethylene-vinyl acetate copolymer grafted with maleic anhydride, the content of vinyl acetate is greater than or equal to 28%.

[0024] In a further technical solution, the cross-linking sensitizer is one or a combination of trimethylolpropane trimethacrylate (TMPTMA) and triallyl isocyanurate (TAIC).

[0025] According to a further technical solution, the other auxiliary agents are a combination of one or more of silicone masterbatch, silane coupling agent and polyethylene wax, methyl silicone oil, zinc stearate and erucamide.

[0026] In a further technical solution, the silane coupling agent is a combination of one or more of vinyl (β-methoxyethoxy) silane, γ-aminopropyl triethoxy silane, and γ-methacryloxypropyl trimethoxy silane.

[0027] Furthermore, the present invention also discloses a method for preparing a low-smoke halogen-free cable material for a soft locomotive cable, comprising:

[0028] Step 1: weigh the resin material, flame retardant, antioxidant, lubricant, silane coupling agent, cross-linking sensitizer and other additives according to the formula ratio, put them into a banbury mixer for mixing at a temperature of 155°C, mix them thoroughly and evenly, and then discharge the materials;

[0029] Step 2: Add the discharge material of step 1 into a twin-screw extruder for mixing, and then send it into a single-screw extruder for granulation; wherein the extrusion temperature of the twin-screw is 120-150° C., the screw speed frequency is 25 Hz, and the extrusion temperature of the single screw is 80-135° C.;

[0030] After extrusion, the material is cooled, sieved and dried to obtain a soft low-smoke halogen-free cable material for locomotive cables.

[0031] The terms “include,” “including,” “have,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0032] The terms used herein generally have the ordinary meanings of each term used in the art, in the context of the present invention, and in the specific context, unless otherwise noted. Certain terms used to describe the present invention will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art regarding the description of the present invention.

[0033] The working principle and advantages of the present invention are as follows:

[0034] 1. The low-smoke halogen-free cable material prepared by the present invention through specific component formula requirements has an environmentally friendly halogen-free formula system and excellent flame retardant performance. When matched with an inner layer of insulating material, it can meet the requirements of EN50264 standard. The material has low hardness and soft feel, which is superior to most similar products.

[0035] 2. The low-smoke halogen-free cable material provided by the present invention has excellent physical and mechanical properties. After 15M electron beam irradiation, the prepared material has a tensile strength of ≥10MPa and an elongation at break of ≥150%. The product has good processing performance and excellent mechanical properties. Its extruded surface is smoother and has no scorching phenomenon.

[0036] 3. The low-smoke halogen-free cable material provided by the present invention meets the requirements of EN50264 standard for cable materials and has excellent oil resistance.

[0037] The invention provides a low-smoke halogen-free cable material for soft locomotive cables and a preparation method thereof. The product has excellent oil resistance, and the double oil resistance strength / elongation change rate according to the EN50264 test standard is ≤±20%, and the softness is good: the Shore A hardness is ≤92A, and the other properties meet the standard requirements. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with embodiments:

[0039] The present invention will be described in detail below. After understanding the embodiments of the present invention, any person skilled in the art can make changes and modifications based on the techniques taught by the present invention without departing from the spirit and scope of the present invention.

[0040] The terms used herein are only for describing specific embodiments and are not intended to be limiting of the present invention. Singular forms such as "a", "this", "here", "this" and "the" as used herein also include plural forms.

[0041] A low-smoke halogen-free cable material for a soft locomotive cable and a preparation method thereof. The low-smoke halogen-free cable material for a soft locomotive cable is composed of the following components in parts by weight, as shown in Table 1, which is a component table of Examples 1 and 2, and Comparative Examples 1 and 2:

[0042] Table 1

[0043]

[0044] The method for preparing the low-smoke halogen-free cable material for soft locomotive cables comprises the following steps:

[0045] Step 1: weigh the resin material, flame retardant, antioxidant, lubricant, silane coupling agent, cross-linking sensitizer and other processing aids according to the formula ratio, put them into a banbury mixer for mixing at a mixing temperature of 150°C, mix them thoroughly and evenly, and then discharge the materials;

[0046] Step 2: Add the discharge material of step 1 into a twin-screw extruder for mixing, and then send it into a single-screw extruder for granulation; wherein the extrusion temperature of the twin-screw is 120-150°C, the screw speed frequency is 25Hz, and the extrusion temperature of the single screw is 80-140°C; after extrusion, cool and sieve, and vacuum pack after drying.

[0047] The low-smoke halogen-free cable materials obtained in Examples 1 and 2 of the present invention and Comparative Examples 1 and 2 were subjected to relevant tests according to the standards, including tensile strength and elongation at break according to GB / T 1040, oxygen index test according to GB / T2406, Shore hardness test according to GB / T 2411, and oil resistance test according to EN 60811-2-1. The obtained data are shown in Table 2:

[0048] Table 2

[0049]

[0050] As can be seen from Table 2, the soft low-smoke halogen-free cable material for locomotive cables of the present invention improves the softness and oil resistance of the product by selecting different resin formula systems (such as increasing the amount of EVA resin with high VA content and EBA resin). In order to improve the tensile strength of the material after irradiation, a small amount of mLLDPE is introduced, so that the material can meet the tensile strength ≥10.0MPa and elongation at break ≥150% after 15M irradiation. In contrast, in Comparative Example 1, in order to reduce the hardness, mLLDPE is not added, and the proportion of high VA content EVA in EVA is too high. Therefore, although the initial hardness of the material is the lowest, the strength after irradiation is not high enough and cannot meet the standard requirement of ≥10MPa; in Comparative Example 2, in order to improve the tensile strength of the material, the amount of EVA is reduced and the amount of mLLDPE is increased. Although the strength is improved after irradiation, the initial hardness is too high.

[0051] The present invention mainly combines the preferred resin system and the cross-linking sensitizer, and can achieve the mechanical properties of tensile strength ≥ 10MPa and elongation at break ≥ 150% after electron beam irradiation on the basis of soft hand feeling and good oil resistance. Under normal circumstances, it is necessary to increase the filling amount under the condition of flame retardancy, and the increase in the filling amount will damage the mechanical properties of the material; softness and high strength are in opposite directions, and a soft hand feeling will cause the tensile strength to be far lower than 10MPa. The present invention solves this contradiction very well. The product has excellent oil resistance. According to the EN50264 test standard, the double oil resistance strength / elongation change rate is ≤±20%, and the softness is good: Shore A hardness ≤92A, and the other properties can meet the standard requirements.

[0052] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-smoke halogen-free cable material for soft locomotive cables, characterized by: The raw materials include the following components by mass: 100 parts of resin material; Flame retardant 130~160 parts; 3~5 parts of antioxidant; 2~4 parts of lubricant; Silane coupling agent 1~3 parts; 1~3 parts of cross-linking sensitizer; 3~6 parts of other additives; Wherein, the resin material is a combination of one or more of ethylene-vinyl acetate copolymer, polyethylene grafted with maleic anhydride, ethylene-vinyl acetate copolymer grafted with maleic anhydride, ethylene-butyl acrylate copolymer, and polyethylene; The antioxidant comprises a primary antioxidant and a secondary antioxidant, wherein the primary antioxidant is a phenolic antioxidant, and the amount of the primary antioxidant is greater than or equal to 50 wt % of the total amount of the antioxidant.

2. The low-smoke zero-halogen cable material for a soft locomotive cable according to claim 1, characterized in that: The flame retardant is a combination of one or more of aluminum hydroxide, magnesium hydroxide and silicon-based carbon-forming agents.

3. The low-smoke zero-halogen cable material for a soft locomotive cable according to claim 1, characterized in that: The primary antioxidant is a combination of one or more of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] pentaerythritol ester, 4,4'-thiobis(6-tert-butyl-3-methylphenol), and 2,2'-thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

4. The low-smoke zero-halogen cable material for a soft motorcycle cable according to claim 1, characterized in that: The secondary antioxidant is a combination of one or more of dilauryl thiodipropionate, distearyl thiodipropionate, and high-temperature phosphite.

5. The low-smoke zero-halogen cable material for a soft locomotive cable according to claim 1, characterized in that: The melt index of the ethylene-vinyl acetate copolymer is 1-7 g / 10 min, and the content of vinyl acetate is 28-70 wt %.

6. The low-smoke zero-halogen cable material for a soft motorcycle cable according to claim 1, characterized in that: The polyethylene has a melt index of 1 to 5 g / 10 min; The melt index of the ethylene-butyl acrylate copolymer is 1-5 g / 10 min, wherein the butyl acrylate content is 20-40 wt %.

7. The low-smoke zero-halogen cable material for a soft motorcycle cable according to claim 1, characterized in that: In the ethylene-vinyl acetate copolymer grafted with maleic anhydride, the content of vinyl acetate is greater than or equal to 28 wt %.

8. The low-smoke zero-halogen cable material for a soft motorcycle cable according to claim 1, characterized in that: The cross-linking sensitizer is one of trimethylolpropane trimethacrylate and triallyl isocyanurate or a combination of the two.

9. The low-smoke zero-halogen cable material for a soft motorcycle cable according to claim 1, characterized in that: The other auxiliary agents are a combination of one or more of silicone masterbatch, silane coupling agent, polyethylene wax, methyl silicone oil, zinc stearate, and erucamide.

10. The low-smoke zero-halogen cable material for a soft motorcycle cable according to claim 1, characterized in that: The silane coupling agent is a combination of one or more of vinyl (β-methoxyethoxy) silane, γ-aminopropyl triethoxy silane, and γ-methacryloxypropyl trimethoxy silane.

11. A method for preparing low-smoke halogen-free cable material for soft locomotive cables, characterized in that: Used to prepare a low-smoke halogen-free cable material for a soft locomotive cable according to any one of claims 1 to 10, the preparation method comprising: Step 1: weigh the resin material, flame retardant, antioxidant, lubricant, silane coupling agent, cross-linking sensitizer and other additives according to the formula ratio, put them into a banbury mixer for mixing at a temperature of 155°C, mix them thoroughly and evenly, and then discharge the materials; Step 2: Add the discharge material of step 1 into a twin-screw extruder for mixing, and then send it into a single-screw extruder for granulation; wherein the extrusion temperature of the twin-screw is 120-150°C, the screw speed frequency is 25Hz, and the extrusion temperature of the single screw is 80-135°C; After extrusion, the material is cooled, sieved and dried to obtain a soft low-smoke halogen-free cable material for locomotive cables.

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