A high-toughness cable composite material and a preparation method and application thereof

Abstract

The application belongs to the technical field of polymer materials and electric wire and cable, and discloses a high-toughness cable composite material and a preparation method and application thereof. The preparation method comprises the following steps: (1) adding silane-terminated liquid polybutadiene, hydroxyl silicone oil and organic tin catalyst into anhydrous solvent, uniformly mixing, heating to 80-100 DEG C to carry out dealcoholization condensation reaction, evaporating the solvent after the reaction is completed, and obtaining a silicone-modified polybutadiene crosslinking agent; (2) adding the obtained silicone-modified polybutadiene crosslinking agent, PE, EVA, reinforcing filler and initiator into an extruder under an oxygen-free atmosphere to carry out melt blending crosslinking reaction, and extruding to form a high-toughness cable composite material. Compared with a conventional vinyl silane crosslinking agent, the silicone-modified polybutadiene crosslinking agent can significantly improve the mechanical strength, flexibility and weather resistance of the obtained crosslinked polyethylene composite material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polymer materials and electric wires and cables, and particularly relates to a high-toughness cable composite material and a preparation method and application thereof. BACKGROUND

[0002] The insulating materials for cables mainly include polyvinyl chloride (PVC), polyethylene (PE), cross-linked polyethylene (XLPE), rubber, silicone rubber and the like. Among them, XLPE is increasingly widely applied due to its good comprehensive performance. Compared with conventional PE materials, XLPE after cross-linking not only significantly improves the mechanical properties, environmental stress cracking resistance, chemical corrosion resistance, creep resistance and electrical properties and other comprehensive properties of PE, but also very obviously improves the temperature resistance.

[0003] The production methods of XLPE include physical cross-linking (radiation cross-linking) and chemical cross-linking. The chemical cross-linking is divided into silane cross-linking and peroxide cross-linking. Among them, silane cross-linked polyethylene insulating material is widely applied as the insulating material of low-voltage power cables in the wire and cable industry. Compared with peroxide cross-linking and radiation cross-linking, the silane cross-linking method has the advantages of simple required manufacturing equipment, convenient operation and low comprehensive cost, and has become the leading material for the insulation of low-voltage cross-linked cables.

[0004] The production method of the existing silane cross-linked polyethylene generally adopts small molecular vinyl silane coupling agents (such as vinyl trimethoxysilane or vinyl triethoxysilane) to cross-link under the conditions of peroxide initiators and dealcoholization condensation catalysts, and the cross-linking mechanism mainly includes: 1. The peroxide initiator initiates a dehydrogenation reaction to generate free radicals on the PE main chain; 2. The free radicals attack the double bond of the vinyl silane coupling agent to realize the grafting of the silane coupling agent; 3. The grafted silane coupling agent is hydrolyzed and dealcoholized to form a cross-linked structure (for details, see Zhang Jianyao et al. Development of Silane Cross-linked Polyethylene Cable Insulating Material. Synthetic Resin and Plastic, 2005, 22(6): 4; Yang Wei et al. Production Process of Silane Cross-linked Polyethylene Cable Insulating Material. Shanghai Chemical Industry, 2003, 12; Xiang Jian et al. Silane Cross-linked Polyethylene Cable Insulating Material. Wire and Cable, 2007, 12).

[0005] However, the existing production method of silane cross-linked polyethylene has the following problems: 1. The small molecule vinyl silane coupling agent has high volatility under the temperature condition of extrusion grafting and poor compatibility with the PE melt, resulting in high loss rate and low grafting rate; 2. In the extrusion process of PE melt grafting silane, in addition to the grafting of PE and silane, there is also C-C cross-linking on the PE molecular chain, which is a competitive reaction with silane grafting. The low content of double bonds in the small molecule vinyl silane coupling agent leads to low silane grafting rate and increased C-C cross-linking reaction of the PE main chain, making the processing performance and toughness of the composite material poor, or by strictly controlling the content ratio of the initiator and the antioxidant to promote grafting, the process control is more complex; 3. The cross-linking process mainly relies on the hydrolysis and alcoholysis of the silane coupling agent, which needs to use a complex high-temperature water vapor cross-linking process, and the silane coupling agent also has a strong coupling reaction with inorganic fillers, resulting in poor controllability of the PE polymer material cross-linking; 4. The polysiloxane chain introduced by the small molecule silane coupling agent cross-linking is short, and the improvement effect on toughness and weather resistance is very limited. SUMMARY

[0006] In view of the shortcomings and deficiencies of the prior art, the primary purpose of the present application is to provide a preparation method of a high-strength and high-toughness cable composite material.

[0007] Another purpose of the present application is to provide a high-strength and high-toughness cable composite material prepared by the above method.

[0008] Still another purpose of the present application is to provide the application of the above high-strength and high-toughness cable composite material in the preparation of wire and cable insulation layers.

[0009] The purpose of the present application is achieved by the following technical solutions:

[0010] A preparation method of a high-strength and high-toughness cable composite material, comprising the following preparation steps:

[0011] (1) The silane-terminated liquid polybutadiene, hydroxyl silicone oil and organotin catalyst are added to anhydrous solvent and mixed uniformly, heated to 80-100℃ for alcoholysis condensation reaction, and after the reaction is completed, the solvent is evaporated to obtain an organosilicon modified polybutadiene cross-linking agent;

[0012] (2) The obtained organosilicon modified polybutadiene cross-linking agent, polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), reinforcing filler and initiator are added to an extruder under an oxygen-free atmosphere for melt blending cross-linking reaction, and extruded to obtain a high-strength and high-toughness cable composite material.

[0013] In the above preparation method, the silane-terminated liquid polybutadiene is a commercially available raw material, and its structural general formula is as follows:

[0014]

[0015] wherein R is generally an alkylene group having 2-3 carbon atoms and R' is generally an alkyl group having 1-2 carbon atoms. The average molecular weight of the silane-terminated liquid polybutadiene is generally 2000-3000 g / mol.

[0016] In the preparation method, the hydroxyl silicone oil is a commercially available raw material, and its general structure is as follows:

[0017]

[0018] The average molecular weight of the hydroxyl silicone oil is 1000-6000 g / mol.

[0019] In the above preparation method, the molar ratio of the silane-terminated liquid polybutadiene to the hydroxyl silicone oil is preferably 1.6-2:1. By controlling the molar ratio of the silane-terminated liquid polybutadiene to the hydroxyl silicone oil to be 1.6-2:1, the obtained organosilicon modified polybutadiene crosslinking agent has silane-terminated liquid polybutadiene at both ends, which can improve the compatibility with PE melt (the polybutadiene segment has better compatibility with PE melt than the polysiloxane segment), and the unsaturated double bonds of the polybutadiene at both ends can more efficiently crosslink with the PE main chain, improving the crosslinking effect; on the other hand, more end group silane coupling groups can be reserved, improving the coupling effect with the reinforcing filler and the condensation crosslinking in the natural environment after extrusion, thereby significantly improving the strength and weather resistance of the composite material. The theoretical reaction formula under the condition that the molar ratio of the silane-terminated liquid polybutadiene to the hydroxyl silicone oil is 2:1 is as follows:

[0020]

[0021] The above reaction is a well-known silastic dealcoholization condensation reaction mechanism in the art. The reaction process of the present application needs to be carried out in anhydrous conditions to prevent premature hydrolysis and condensation crosslinking of the coupling groups. The completion of the reaction can be determined by measuring the hydroxyl value content. The product crosslinked in advance will significantly reduce the compatibility with PE melt, resulting in a decrease in the melt blending crosslinking reaction effect.

[0022] In the above preparation method, the anhydrous solvent is benzene, toluene, xylene, carbon tetrachloride or chloroform. The above anhydrous solvent has good solubility for the silane-terminated liquid polybutadiene, the hydroxyl silicone oil and the organotin catalyst, and can promote the completion of the dealcoholization condensation reaction.

[0023] In the above preparation method, the time of the dealcoholization condensation reaction is 1-4 h. The completion of the dealcoholization condensation reaction can be determined by measuring the hydroxyl value content of the product.

[0024] ​​In the preparation method, the polyethylene is a mixture of one or both of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE).

[0025] In the preparation method, the reinforcing filler is one or more of nano calcium carbonate, nano silicon dioxide, and nano kaolin.

[0026] In the preparation method, the initiator is dicumyl peroxide (DCP).

[0027] In the preparation method, the mass ratio of the raw materials in step (2) is as follows: 0.5-3 parts of the silicone-modified polybutadiene crosslinking agent, 65-100 parts of PE, 5-20 parts of EVA, 5-15 parts of the reinforcing filler, and 0.05-0.1 of the initiator.

[0028] In the preparation method, the temperature of the melt blending crosslinking reaction is 160-200°C, and the time is 5-30 min.

[0029] A high-toughness cable composite material is prepared by the method.

[0030] The high-toughness cable composite material is applied to the preparation of an insulation layer of an electric wire or cable.

[0031] Compared with the prior art, the present application has the following advantages:

[0032] (1) The present application uses a silicone-modified polybutadiene crosslinking agent with a higher molecular weight to replace a small-molecule vinyl silane crosslinking agent, which has good compatibility with a PE melt and no volatile loss, can significantly improve the crosslinking effect and reduce the cost of loss.

[0033] (2) The silicone-modified polybutadiene crosslinking agent used in the present application has a high content of unsaturated double bonds, which realizes crosslinking through a large number of double bonds in the polybutadiene molecular chain segment. On the one hand, the crosslinking of C-C on the PE molecular chain is inhibited, which has less effect on the PE molecular backbone, and can ensure good processing performance and toughness. On the other hand, the crosslinking does not need to be realized through the hydrolysis-dealcoholization condensation of a silane coupling agent. The contained silane coupling agent can participate in the coupling reaction of inorganic reinforcing fillers, thereby significantly improving the mechanical strength of the product.

[0034] (3) The silicone-modified polybutadiene crosslinking agent used in the present application introduces long-chain polysiloxane with better softness and weather resistance through crosslinking, which can significantly improve the flexibility and weather resistance of the composite material. DETAILED DESCRIPTION

[0035] The present application will be further described in detail below in conjunction with examples, but the embodiments of the present application are not limited thereto. EXAMPLE

[0036] A method for preparing a high toughness cable composite material, comprising the following preparation steps:

[0037] (1) A silane-terminated liquid polybutadiene (WINCRETE POLYVEST ST-E, average molecular weight 3000 g / mol) and a hydroxyl silicone oil (average molecular weight 5000 g / mol) are mixed with a molar ratio of 2:1 and 0.5 wt% (relative to the amount of polymerization raw material, the same below) dibutyltin dilaurate catalyst in a dry and dehydrated toluene solvent, and then heated to 90°C under nitrogen protection for 2h of dealcoholization condensation reaction. The product hydroxyl value is determined to determine the completion of the reaction, and then the solvent is removed by evaporation under reduced pressure to obtain a silicone-modified polybutadiene crosslinking agent.

[0038] (2) The obtained silicone-modified polybutadiene crosslinking agent is mixed with LDPE, EVA, nano calcium carbonate reinforcing filler and DCP initiator in a nitrogen deoxidized extruder with a mass ratio of n:80:10:10:0.06. The blending crosslinking reaction temperature is controlled at 180-200°C, and the time is controlled at 10 min. Then it is extruded into a mold and cooled to form a high toughness cable composite material.

[0039] The mass ratio n of the silicone-modified polybutadiene crosslinking agent in this embodiment is adjusted to 0, 0.5, 1, 1.5, 2 and 3 respectively to obtain crosslinked polyethylene composite materials under different addition amounts of silicone-modified polybutadiene crosslinking agent.

[0040] The tensile strength, elongation at break (GB / T 528-2009) and heat aging resistance (GB / T 7141-2008, exposure temperature 110°C, time 240h; then test the tensile strength retention rate) of the crosslinked polyethylene composite materials obtained under different addition amounts of silicone-modified polybutadiene crosslinking agent in this embodiment are tested, and the results are shown in Table 1 below.

[0041] Table 1 Performance of composite materials under different crosslinking agent addition amounts

[0042] Crosslinking agent addition amount 0 0.5 1 1.5 2 3 Tensile strength / MPa 27 34 41 48 53 55 Elongation at break / % 285 350 381 426 367 310 Heat aging strength retention rate / % 72 83 89 94 95 94

[0043] As can be seen from the results of Table 1, the PE material is crosslinked by the silicone-modified polybutadiene crosslinking agent, which can significantly improve the mechanical strength, toughness and aging resistance of the composite material. With the increase of the content of the silicone-modified polybutadiene crosslinking agent, the mechanical strength and aging resistance of the obtained composite material gradually increase, and the elongation at break first increases and then decreases. The reason is that the increase of the crosslinking degree can enhance the strength and aging resistance of the composite material, but will reduce the elongation at break of the material, while the introduction of the high-elasticity polybutadiene segment and the high-softness polysiloxane segment can improve the elongation at break of the material; at the same time, the high-heat-resistant polysiloxane segment can improve the aging resistance of the material, and the reduction of the content of the unsaturated double bond of the crosslinked polybutadiene segment is beneficial to improve the aging resistance of the material. Example

[0044] A preparation method of a high-strength and high-toughness cable composite material, comprising the following preparation steps:

[0045] (1) The silane-terminated liquid polybutadiene (Yingchuang POLYVEST ST-E, average molecular weight 3000 g / mol) and the hydroxyl silicone oil (average molecular weight 3000 g / mol) are mixed with 0.5 wt% dibutyltin dilaurate catalyst in a molar ratio of 1.8:1 and 0.5 wt% dibutyltin dilaurate catalyst in a dry and dehydrated toluene solvent, and then heated to 80°C under nitrogen protection for 4h of de-alcohol condensation reaction. The product hydroxyl value is determined to determine the completion of the reaction, and then the solvent is removed by evaporation under reduced pressure to obtain a silicone-modified polybutadiene crosslinking agent.

[0046] (2) The obtained silicone-modified polybutadiene crosslinking agent, LDPE, LLDPE, EVA, nano-silicon dioxide reinforcing filler and DCP initiator are added to the nitrogen deoxidized extruder in a mass ratio of 1.5:75:15:15:5:0.08 for melt blending crosslinking reaction, the blending crosslinking reaction temperature is controlled at 180-200°C, and the time is controlled at 15min, then extruded into a mold and cooled to form a high-strength and high-toughness cable composite material.

[0047] The composite material obtained in this example has a tensile strength of 42 MPa, an elongation at break of 490%, and a thermal aging strength retention rate of 92% after performance testing. Example

[0048] A preparation method of a high-strength and high-toughness cable composite material, comprising the following preparation steps:

[0049] (1) Silane-terminated liquid polybutadiene (WINCRETE POLYVEST ST-E, average molecular weight of 3000 g / mol) and hydroxyl silicone oil (average molecular weight of 1000 g / mol) were mixed in a molar ratio of 1.6:1 and 0.5 wt% dibutyltin dilaurate catalyst was added to the dry and dehydrated toluene solvent, and the mixture was uniformly mixed, heated to 100°C under nitrogen protection, and subjected to dealcoholization condensation reaction for 1 h. The product hydroxyl value was determined to determine the completion of the reaction, and then the solvent was removed under reduced pressure to obtain a silicone-modified polybutadiene crosslinking agent.

[0050] (2) The obtained silicone-modified polybutadiene crosslinking agent, LDPE, EVA, nano-silicon dioxide reinforcing filler and DCP initiator were added to the nitrogen deoxidized extruder in a mass ratio of 1.5:65:5:5:0.05 for melt blending crosslinking reaction, the blending crosslinking reaction temperature was controlled at 180-200°C, and the time was controlled for 5 min, then extruded into a mold and cooled to form a high-toughness cable composite material.

[0051] The composite material obtained in this example has a tensile strength of 50 MPa, an elongation at break of 385%, and a heat aging strength retention rate of 94%.

[0052] Comparative Example 1

[0053] A method for preparing a silane crosslinked polyethylene cable composite material, comprising the following preparation steps:

[0054] Vinyl triethoxysilane crosslinking agent, LDPE, EVA, nano-calcium carbonate reinforcing filler and DCP initiator were added to the nitrogen deoxidized extruder in a mass ratio of 1.5:80:10:10:0.06 for melt blending to perform the first step grafting reaction, the grafting reaction temperature was controlled at 180-200°C, and the time was controlled for 10 min, then 0.5 wt% dibutyltin dilaurate catalyst was added and a small amount of water vapor was introduced for the second step crosslinking reaction for 5 min, and then the reaction was completed. The extrusion was cooled to form a silane crosslinked polyethylene cable composite material.

[0055] The composite material obtained in this example has a tensile strength of 38 MPa, an elongation at break of 212%, and a heat aging strength retention rate of 85%.

[0056] Through the comparison results of this comparative example and example 1, it can be seen that the silicone-modified polybutadiene crosslinking agent of the present application can significantly improve the mechanical strength, flexibility and weather resistance of the obtained composite material compared with the conventional vinyl silane crosslinking agent.

[0057] Comparative Example 2

[0058] The comparative example is compared with example 1, and a silane-terminated liquid polybutadiene (Yingchuang POLYVEST ST-E, average molecular weight 3000 g / mol) with equal mass ratio n = 1.5 is used to replace the silicone-modified polybutadiene crosslinking agent, and the rest is the same.

[0059] The composite material obtained in the comparative example is tested for performance, and the tensile strength is 41 MPa, the elongation at break is 304%, and the heat aging strength retention rate is 79%.

[0060] It can be seen from the comparison between the comparative example and example 1 that the silicone-modified polybutadiene crosslinking agent of the application can significantly improve the mechanical strength, flexibility and weather resistance of the obtained composite material compared with the unmodified silane-terminated liquid polybutadiene crosslinking agent, and the improvement of flexibility and weather resistance is particularly significant.

[0061] The above examples are preferred embodiments of the application, but the embodiments of the application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the application shall be equivalent replacement methods, and shall be included in the protection scope of the application.

Claims

1. A method of making a high tenacity cable composite material, characterized by, It comprises the following preparation steps: (1) adding silane-terminated liquid polybutadiene, hydroxyl silicone oil and organotin catalyst into anhydrous solvent, mixing uniformly, heating to 80-100℃ to carry out dealcohol condensation reaction, evaporating solvent after reaction is completed, obtaining silicone-modified polybutadiene crosslinking agent; (2) adding the obtained silicone-modified polybutadiene crosslinking agent, PE, EVA, reinforcing filler and initiator into an extruder under oxygen-free atmosphere to carry out melt blending crosslinking reaction, extruding to form, obtaining high-toughness cable composite material; The structure general formula of the silane-terminated liquid polybutadiene in step (1) is as follows: ， In the formula, R is alkylene with carbon atom number of 2-3, and R' is alkyl with carbon atom number of 1-2; The molar ratio of the silane-terminated liquid polybutadiene to hydroxyl silicone oil is 1.6-2:1; The mass ratio of the raw materials added in step (2) is as follows: silicone-modified polybutadiene crosslinking agent 0.5-3 parts, PE 65-100 parts, EVA 5-20 parts, reinforcing filler 5-15 parts, and initiator 0.05-0.1 parts.

2. The method for preparing a high-strength and high-toughness cable composite material according to claim 1, characterized in that, The average molecular weight of the silane-terminated liquid polybutadiene is 2000-3000 g / mol, and the average molecular weight of the hydroxyl silicone oil is 1000-6000 g / mol.

3. The method for preparing a high-strength and high-toughness cable composite material according to claim 1, characterized in that, The anhydrous solvent is benzene, toluene, xylene, carbon tetrachloride or chloroform, and the time of the dealcohol condensation reaction is 1-4 h.

4. The method for preparing a high-strength and high-toughness cable composite material according to claim 1, characterized in that, The PE uses one or a mixture of both of LDPE and LLDPE.

5. The method for preparing a high-strength and high-toughness cable composite material according to claim 1, characterized in that, The reinforcing filler uses one or several of nano calcium carbonate, nano silicon dioxide and nano kaolin, and the initiator uses DCP.

6. The method for preparing a high-strength and high-toughness cable composite material according to claim 1, characterized in that, The temperature of the melt blending crosslinking reaction is 160-200℃, and the time is 5-30 min.

7. A high tenacity cable composite material, characterized by, It is prepared by the method of any one of claims 1-6.

8. Application of the high-toughness cable composite material of claim 7 in the preparation of wire and cable insulation layer.

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