A silane cross-linked polyethylene material and preparation method thereof

Abstract

The present application belongs to the technical field of functional cable masterbatch, and specifically discloses a silane cross-linked polyethylene material. A silane cross-linked polyethylene material of the present application is mainly prepared by the following components in parts by weight: 240-300 parts of polyethylene composite resin, 20-28 parts of modified silane cross-linking agent, 12-16 parts of stabilizer, 10-16 parts of initiator, 12-14 parts of antioxidant, 20-24 parts of catalyst, 50-70 parts of reinforcing agent, 26-30 parts of elastomer, 6-8 parts of water absorbent and 60-70 parts of auxiliary agent carrier. The present application improves the cross-linking transition strength of the cable material by adding a modified silane cross-linking agent, and simultaneously adds a stabilizer to improve the electrical properties of the cable material.

Description

Technical Field

[0001] The present application relates to the technical field of functional cable masterbatches, and in particular to a silane cross-linked polyethylene material and a preparation method thereof. Background Art

[0002] With the continuous development of modern power systems, cross-linked polyethylene materials are widely used in power cables, overhead cables and various control cables due to their good heat resistance, excellent electrical insulation properties and easy laying after being made into cables. They have gradually become the dominant material in the field of medium and low voltage cables.

[0003] In the prior art, polyethylene material is usually used as the main body, and then other additives are mixed into it through physical and chemical methods to enhance the comprehensive performance of the finished polyethylene material. At the same time, various types of cross-linked polyethylene cable materials are made through relevant cross-linking technologies (such as radiation cross-linking, ultraviolet light cross-linking, peroxide cross-linking and silane cross-linking, etc.) to improve other physical and chemical properties, such as elasticity, hardness, toughness, durability and chemical stability; however, semi-finished cross-linked polyethylene cable materials usually need to be boiled in a warm water pool with a water temperature of about 90°C or a high-temperature steam room (temperature above 80°C) for about 8-10 hours to complete the cross-linking transformation of the molecules from linear structure to network structure.

[0004] In view of the above technology, the inventor believes that the existing cross-linked polyethylene cable material is not only easy to introduce water into the conductor layer during the subsequent warm water processing step to oxidize it, resulting in a decrease in the conductivity of the conductor; but also has high requirements for the warm water processing site conditions and consumes more energy. Therefore, it is very necessary to develop a polyethylene cable material that can quickly complete the cross-linking transformation. Summary of the invention

[0005] In order to quickly complete the cross-linking transformation of polyethylene materials, the present application provides a silane cross-linked polyethylene material and a preparation method thereof.

[0006] In the first aspect, the present application provides a silane cross-linked polyethylene material, comprising the following components in parts by weight: 240-300 parts of a polyethylene composite resin, 20-28 parts of a modified silane cross-linking agent, 12-16 parts of a stabilizer, 10-16 parts of an initiator, 12-14 parts of an antioxidant, 20-24 parts of a catalyst, 50-70 parts of a reinforcing agent, 26-30 parts of an elastomer, 6-8 parts of a water absorbent, and 60-70 parts of an auxiliary agent carrier.

[0007] By adopting the above technical scheme, polyethylene composite resin is used as the main body, and a modified silane cross-linking agent is added to quickly graft silane chains on the long chain of the polyethylene main body to improve its physical properties and stability, while improving the cross-linking compounding degree for other additives; other additives are compounded through an additive carrier and mixed into the polyethylene main body to enhance the comprehensive performance of the cable material, such as adding a stabilizer to inhibit the generation of space charge, thereby stabilizing the cable voltage; adding an initiator to improve the reaction efficiency and reaction yield; adding an antioxidant to enhance the durability of the cable material and avoid aging; adding a catalyst to also promote the reaction efficiency of the cross-linking condensation reaction; adding a reinforcing agent and an elastomer to jointly improve the physical and mechanical properties of the cable material, such as strength, elasticity, toughness, etc.; adding a water absorbent to absorb and dry the moisture introduced into the inside of the sheath in the molding process step.

[0008] Preferably, the modified silane crosslinking agent comprises the following components in parts by weight: 40-56 parts of dimethylchlorosilane, 18-24 parts of boron trifluoride, 46-50 parts of 1,7-octadiene, 30-40 parts of divinylbenzene, and 20-28 parts of Karstedt catalyst.

[0009] Preferably, the preparation method of the modified silane crosslinking agent comprises the following steps:

[0010] S1. Under nitrogen protection, 1,7-octadiene, boron trifluoride and Karstedt catalyst are mixed, the temperature is raised to 45-55° C., and the mixture is stirred and activated for 40-60 minutes to obtain a reaction base material;

[0011] S2. Dimethylchlorosilane is added dropwise to the reaction base material in step S1 at a rate of 10-20 mL / min. After the addition is complete, divinylbenzene is added and mixed evenly. After the reaction is carried out at a constant temperature for 10-12 hours, the mixture is distilled under reduced pressure to obtain a modified silane crosslinking agent.

[0012] By adopting the above technical method, dimethylchlorosilane and 1,7-octadiene are used as main raw materials, and a functional end-capping reactant is prepared through a hydrosilylation reaction; a Karstedt catalyst is then used to reduce the activation energy required for the reaction to promote the speed and progress of the reaction; and at the same time, free radical copolymerization is carried out in combination with acidic boron trifluoride to make the main chain molecule have a highly electron-deficient characteristic, thereby improving the cross-linking activity of the reaction intermediate, and boron trifluoride also has a catalytic effect, which helps the reaction intermediate to be compounded with divinylbenzene which also has a cross-linking effect, so that the prepared modified silane cross-linking agent has a higher cross-linking strength, can promote the mutual combination of the polyethylene main body and other additives and quickly complete the cross-linking transformation, thereby improving the industrial production efficiency.

[0013] Preferably, the stabilizer comprises 4-aminobenzophenone and 9,10-bis(4-methoxyphenyl)anthracene, and the mass ratio of the 4-aminobenzophenone to the 9,10-bis(4-methoxyphenyl)anthracene is 1:(0.30-0.50).

[0014] By adopting the above technical method and selecting benzophenone derivatives as stabilizers, the space charge generated when the polyethylene material is molded and sleeved with DC cables can be suppressed, and high-energy electrons in the insulating material under strong electric fields can be captured, and the breakdown strength of the material can be improved, thereby improving its electrical properties and further stabilizing the voltage. It is mainly to prevent the ionization of mobile charges injected by external electrodes, carriers captured by traps, and organic or inorganic impurities, so as to delay the aging of polyethylene materials and avoid the risk of partial discharge causing the polymer sheath to be broken down, which seriously affects the reliability and service life of polyethylene cable materials.

[0015] Preferably, the polyethylene composite resin comprises high-density polyethylene, linear low-density polyethylene and medium-density polyethylene, and the mass ratio of the high-density polyethylene, the linear low-density polyethylene and the medium-density polyethylene is 1:(0.50-1.20):(0.30-0.40).

[0016] By adopting the above technical scheme, three polyethylene materials with different physical properties are blended, which can not only give full play to the dense molecular structure of high-density polyethylene to improve the density and strength of the blended material, but also give full play to the relatively loose molecular structure of linear low-density polyethylene to improve the flexibility of the blended material; through many experiments, it was found that the blending ratio of mass ratio of 1: (0.50-1.20): (0.30-0.40) can effectively adjust the physical properties of the mixture, such as hardness, strength, flexibility, etc., while also reducing production costs and making the production process more flexible to meet different production needs.

[0017] Preferably, the initiator is dibenzoyl peroxide.

[0018] By adopting the above technical solution, dibenzoyl peroxide is selected as a free radical polymerization initiator, which can be thermally decomposed at a relatively low temperature to generate a large number of free radicals to promote the polymerization reaction between polyethylene and other additives. In addition, dibenzoyl peroxide can also adjust the molecular weight of the polymerization reaction in the system and control the condensation reaction time, reduce the probability of cracking and rearrangement reaction between silicon-silicon bonds, so as to generate a silane grafted material with a larger molecular weight, and further improve the weight average molecular weight and yield of the polyethylene material.

[0019] Preferably, the catalyst is one or more of isopropyl octyl triacyloxy titanate and isopropyl tristearate titanate.

[0020] By adopting the above technical solution, titanate derivatives are selected as catalysts, which show good controllability in the reaction system and can effectively adjust the reaction rate and reaction selectivity; they have high reaction activity and catalytic efficiency, can play a good catalytic effect under mild reaction conditions, and have high raw material utilization rate for modified silane crosslinking agents. At the same time, compared with traditional catalysts, titanate derivative catalysts not only have higher stability and can be recycled repeatedly, but also have less toxicity to the environment and human body, and have higher application prospects.

[0021] Preferably, the reinforcing agent comprises mica powder and carbon black, and the mass ratio of the mica powder to the carbon black is 1:(1.30-1.50);

[0022] The elastomer is EPDM rubber particles, and the particle size of the EPDM rubber particles is 0.50-0.80 nm.

[0023] By adopting the above technical scheme, mica powder and carbon black materials are used as reinforcing agents, among which mica powder has good insulation performance and high temperature resistance, and can be combined with carbon black to adjust the electrical properties and thermal stability of polyethylene cable materials; carbon black has conductivity and voltage resistance, and can improve the electrical properties of polyethylene cable materials; at the same time, both carbon black and mica powder can absorb ultraviolet rays, thereby reducing the aging speed and loss of polyethylene cable materials and extending the service life; carbon black can also cooperate with mica powder to enhance the material hardness of polyethylene cable materials, thereby improving its wear resistance, cut resistance and heat resistance.

[0024] EPDM rubber particles are used as elastomers, and their particle size is controlled to balance the hardness and strength brought by the reinforcing agent to the polyethylene cable material, so that it can further have considerable elasticity and ductility on this basis, so that the polyethylene cable material can still maintain good recovery performance in high or low temperature environments; by mixing in EPDM rubber particles, it can have good chemical stability and is not corroded by most chemical substances, thereby ensuring the sealing performance of the polymer wrapping sleeve; and EPDM rubber particles combined with polyethylene main material can also improve its molding performance, making the product polyethylene cable material suitable for various processing methods, thereby making it easier to process and produce.

[0025] Preferably, the antioxidant is one or more of antioxidant 1010, antioxidant 168 and antioxidant DLTP;

[0026] The water absorbing agent is one or more of magnesium chloride, calcium chloride and aluminum chloride;

[0027] The auxiliary agent carrier is one or more of ethylene-vinyl acetate copolymer, ethylene vinyl acetate copolymer and ethylene acrylic acid copolymer.

[0028] In the second embodiment, the present application provides a method for preparing a silane cross-linked polyethylene material, comprising the following steps:

[0029] S1. A polyethylene composite resin accounting for 80-85% of the total amount is vacuum dried, heated to 110-130° C., a modified silane crosslinking agent, a catalyst and an initiator are added and mixed, the temperature is raised to 160-220° C., and a reinforcing agent and an elastomer pretreated with a mass fraction of 70-80% ethanol solution are added and mixed and stirred at a speed of 200-500 r / min to obtain a silane grafted material;

[0030] S2. Control the temperature at 70-80°C, add antioxidant, stabilizer, water absorbent and auxiliary agent carrier to the remaining polyethylene composite resin, mix and stir at a speed of 100-300r / min to obtain an auxiliary agent masterbatch, heat to 150-200°C, add the auxiliary agent masterbatch to the silane grafted material, mix and stir at a speed of 500-700r / min, extrude and granulate, and obtain the silane cross-linked polyethylene material.

[0031] By adopting the above technical scheme, a two-step method is used to prepare silane cross-linked polyethylene material, firstly, most of the polyethylene composite resin and the modified silane cross-linking agent, the catalyst and the initiator are mixed and reacted, and the pre-treated reinforcing agent and the elastomer are combined to obtain the silane grafted material body; then a small part of the polyethylene composite resin is combined with the auxiliary agent carrier coated with the antioxidant, the stabilizer and the water absorbent to mix and react, so as to obtain the auxiliary agent masterbatch capable of adjusting the physicochemical properties of the main body; finally, the silane grafted material and the auxiliary agent masterbatch are combined to generate the silane cross-linked polyethylene material, so that the product silane cross-linked polyethylene material can be prepared in a relatively stable and controllable manner, and impurities and impure substances can be removed at any step of the synthesis process to obtain a higher purity precursor, which is helpful to improve the production quality of the finished product.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. In the present application, a polyethylene composite resin is used as the main body, and a modified silane cross-linking agent is added to quickly graft silane chains on the long chain of the polyethylene main body to improve its physical properties and stability, and at the same time improve the cross-linking compounding degree for other additives; other additives are compounded through an additive carrier and mixed into the polyethylene main body to enhance the comprehensive performance of the cable material, such as adding a stabilizer to inhibit the generation of space charge, thereby stabilizing the cable voltage; adding an initiator to improve the reaction efficiency and reaction yield; adding an antioxidant to enhance the durability of the cable material and avoid aging; adding a catalyst to also promote the reaction efficiency of the cross-linking condensation reaction; adding a reinforcing agent and an elastomer to jointly improve the physical and mechanical properties of the cable material, such as strength, elasticity, toughness, etc.; adding a water absorbent to absorb and dry the moisture introduced into the inside of the sheath during the molding process.

[0034] 2. In the present application, dimethylchlorosilane and 1,7-octadiene are used as main raw materials, and a functional end-capping reactant is prepared by a hydrosilylation reaction; a Karstedt catalyst is then used to reduce the activation energy required for the reaction to promote the speed and progress of the reaction; at the same time, free radical copolymerization is carried out with acidic boron trifluoride to make the main chain molecule highly electron-deficient, thereby improving the cross-linking activity of the reaction intermediate, and boron trifluoride also has a catalytic effect, which helps the reaction intermediate to be compounded with divinylbenzene which also has a cross-linking effect, so that the prepared modified silane cross-linking agent has a higher cross-linking strength, which can promote the mutual combination of the polyethylene main body and other additives and quickly complete the cross-linking transformation, thereby improving the industrial production efficiency.

[0035] 3. In this application, benzophenone derivatives are selected as stabilizers, which can suppress the space charge generated when the polyethylene material is molded and sheathed into a DC cable, capture high-energy electrons in the insulating material under a strong electric field, and improve the breakdown strength of the material, thereby improving its electrical properties and further stabilizing the voltage. It is mainly to prevent the ionization of mobile charges injected by external electrodes, carriers captured by traps, and organic or inorganic impurities, so as to delay the aging of polyethylene materials and avoid the risk of partial discharge causing the polymer sheath to be broken down, which seriously affects the reliability and service life of polyethylene cable materials. DETAILED DESCRIPTION

[0036] The present application is further described in detail below with reference to the embodiments.

[0037] The raw materials used in the examples and comparative examples can all be obtained commercially.

[0038] Preparation Example

[0039] Preparation of modified silane crosslinking agent

[0040] Preparation Example 1, a method for preparing a modified silane crosslinking agent, prepared by the following method:

[0041] (1) Under nitrogen protection, 48 g of 1,7-octadiene, 21 g of boron trifluoride and 24 g of Karstedt catalyst were mixed, the temperature was raised to 50° C., and stirred for activation for 50 min to obtain a reaction base material;

[0042] (2) 48 g of dimethylchlorosilane was added dropwise to the reaction base material in step (1) at a rate of 15 mL / min. After the addition was complete, 35 g of divinylbenzene was added and mixed evenly. After the reaction was kept at a constant temperature for 11 hours, the mixture was distilled under reduced pressure to obtain a modified silane crosslinking agent.

[0043] Preparation Example 2, a method for preparing a modified silane crosslinking agent, prepared by the following method:

[0044] (1) Under nitrogen protection, 50 g of 1,7-octadiene, 24 g of boron trifluoride and 28 g of Karstedt catalyst were mixed, the temperature was raised to 55° C., and stirred for activation for 60 min to obtain a reaction base material;

[0045] (2) 56 g of dimethylchlorosilane was added dropwise to the reaction base material in step (1) at a rate of 20 mL / min. After the addition was complete, 40 g of divinylbenzene was added and mixed evenly. After the reaction was kept at a constant temperature for 12 h, the mixture was distilled under reduced pressure to obtain a modified silane crosslinking agent.

[0046] Preparation Example 3, a method for preparing a modified silane crosslinking agent, prepared by the following method:

[0047] (1) Under nitrogen protection, 46 g of 1,7-octadiene, 18 g of boron trifluoride and 20 g of Karstedt catalyst were mixed, the temperature was raised to 45° C., and stirred for activation for 40 min to obtain a reaction base material;

[0048] (2) 40 g of dimethylchlorosilane was added dropwise to the reaction base material in step (1) at a rate of 10 mL / min. After the addition was complete, 30 g of divinylbenzene was added and mixed evenly. After the reaction was kept at a constant temperature for 10 h, the mixture was distilled under reduced pressure to obtain a modified silane crosslinking agent.

[0049] Preparation Example 4, a method for preparing a modified silane crosslinking agent, differs from Preparation Example 1 in that boron trifluoride is not added in step (1).

[0050] Preparation Example 5, a method for preparing a modified silane crosslinking agent, is different from Preparation Example 1 in that no Karstedt catalyst is added in step (1).

[0051] Preparation Example 6, a method for preparing a modified silane crosslinking agent, differs from Preparation Example 1 in that divinylbenzene is not added in step (2).

[0052] Example

[0053] Embodiment 1, a silane cross-linked polyethylene material, the preparation method of the polyethylene material comprises the following steps:

[0054] (1) 230 g of polyethylene composite resin accounting for 85% of the total amount was vacuum dried, heated to 120° C., 24 g of modified silane crosslinking agent, 22 g of catalyst and 13 g of initiator were added and mixed, the temperature was raised to 190° C., and 60 g of reinforcing agent pretreated with 80% by mass ethanol solution and 28 g of elastomer were added and mixed at a speed of 400 r / min to obtain a silane grafted material; (2) The temperature was controlled at 75° C., 13 g of antioxidant, 14 g of stabilizer, 7 g of water absorbent and 65 g of auxiliary agent carrier were added to the remaining 40 g of polyethylene composite resin and mixed at a speed of 200 r / min to obtain an auxiliary agent masterbatch, the temperature was raised to 175° C., the auxiliary agent masterbatch was added to the silane grafted material and mixed at a speed of 600 r / min, and extruded and granulated to obtain the silane crosslinked polyethylene material.

[0055] The modified silane crosslinking agent is derived from Preparation Example 1, and the silane crosslinked polyethylene material prepared in this Example 1 is applied to the insulation layer of power cables of 10 kV and below.

[0056] Embodiment 2, a silane cross-linked polyethylene material, the preparation method of the polyethylene material comprises the following steps:

[0057] (1) 255 g of polyethylene composite resin, accounting for 85% of the total amount, was vacuum dried and heated to 130° C., 28 g of modified silane crosslinking agent, 24 g of catalyst and 16 g of initiator were added and mixed, the temperature was raised to 220° C., and 70 g of reinforcing agent pretreated with 80% by mass ethanol solution and 30 g of elastomer were added and mixed at a speed of 500 r / min to obtain a silane grafted material; (2) The temperature was controlled at 80° C., 14 g of antioxidant, 16 g of stabilizer, 8 g of water absorbent and 70 g of auxiliary agent carrier were added to the remaining 45 g of polyethylene composite resin and mixed at a speed of 300 r / min to obtain an auxiliary agent masterbatch, the temperature was raised to 200° C., the auxiliary agent masterbatch was added to the silane grafted material and mixed at a speed of 700 r / min, and extruded and granulated to obtain the silane crosslinked polyethylene material.

[0058] The modified silane crosslinking agent is derived from Preparation Example 1.

[0059] Embodiment 3, a silane cross-linked polyethylene material, the preparation method of the polyethylene material comprises the following steps:

[0060] (1) 192 g of polyethylene composite resin, accounting for 85% of the total amount, was vacuum dried, heated to 110° C., 20 g of modified silane crosslinking agent, 20 g of catalyst and 10 g of initiator were added and mixed, the mixture was heated to 160° C., and 50 g of reinforcing agent pretreated with 70% by mass ethanol solution and 26 g of elastomer were added and mixed at a speed of 200 r / min to prepare a silane grafted material;

[0061] (2) Controlling the temperature at 70° C., adding 12 g of antioxidant, 12 g of stabilizer, 6 g of water absorbent and 60 g of auxiliary agent carrier to the remaining 48 g of polyethylene composite resin, mixing and stirring at a speed of 100 r / min to obtain an auxiliary agent masterbatch, raising the temperature to 150° C., and then adding the auxiliary agent masterbatch to the silane grafted material, kneading and stirring at a speed of 500 r / min, and extruding and granulating to obtain the silane cross-linked polyethylene material.

[0062] The modified silane crosslinking agent is derived from Preparation Example 1.

[0063] Example 4, a silane cross-linked polyethylene material, is different from Example 1 in that the modified silane cross-linking agent is derived from Preparation Example 2.

[0064] Example 5, a silane cross-linked polyethylene material, is different from Example 1 in that the modified silane cross-linking agent is derived from Preparation Example 3.

[0065] Example 6, a silane cross-linked polyethylene material, is different from Example 1 in that the modified silane cross-linking agent is derived from Preparation Example 4.

[0066] Example 7, a silane cross-linked polyethylene material, is different from Example 1 in that the modified silane cross-linking agent is derived from Preparation Example 5.

[0067] Example 8, a silane cross-linked polyethylene material, is different from Example 1 in that the modified silane cross-linking agent is derived from Preparation Example 6.

[0068] Example 9, a silane cross-linked polyethylene material, differs from Example 1 in that no catalyst is added in step (1).

[0069] Example 10, a silane cross-linked polyethylene material, differs from Example 1 in that no initiator is added in step (1).

[0070] Example 11, a silane cross-linked polyethylene material, differs from Example 1 in that no reinforcing agent is added in step (1).

[0071] Example 12, a silane cross-linked polyethylene material, differs from Example 1 in that no elastomer is added in step (1).

[0072] Example 13, a silane cross-linked polyethylene material, differs from Example 1 in that no antioxidant is added in step (2).

[0073] Example 14, a silane cross-linked polyethylene material, differs from Example 1 in that no stabilizer is added in step (2).

[0074] Example 15, a silane cross-linked polyethylene material, differs from Example 1 in that no water absorbent is added in step (2).

[0075] Example 16, a silane cross-linked polyethylene material, differs from Example 1 in that no auxiliary agent carrier is added in step (2).

[0076] Comparative Example

[0077] Comparative Example 1 is a silane cross-linked polyethylene material, which is different from Example 1 in that in the preparation method of the silane cross-linked polyethylene material, the modified silane cross-linking agent is replaced by an equal amount of vinyltrimethoxysilane.

[0078] Comparative Example 2 is a silane cross-linked polyethylene material. The difference from Example 1 is that in the preparation method of the silane cross-linked polyethylene material, an equal amount of aluminum oxide nanoparticles is used as a stabilizer and is added to the polyethylene material by physical blending.

[0079] Comparative Example 3, a silane cross-linked polyethylene material, is different from Example 1 in that in the preparation method of the silane cross-linked polyethylene material, the catalyst is replaced by an equal amount of a tin catalyst (dibutyltin laurate compound). Among them, the tin catalyst can be selected from one or more of dibutyltin dilaurate, di-n-octyltin dilaurate and dibutyltin laurate maleate.

[0080] Comparative Example 4 is a silane cross-linked polyethylene material. The difference from Example 1 is that in the preparation method of the silane cross-linked polyethylene material, the initiator is replaced by an equal amount of diisopropylbenzene peroxide.

[0081] Comparative Example 5 is a silane cross-linked polyethylene material, which is different from Example 1 in that in the preparation method of the silane cross-linked polyethylene material, the antioxidant is replaced by an equal amount of hindered phenol antioxidant.

[0082] Comparative Example 6 is a silane cross-linked polyethylene material, which is different from Example 1 in that in the preparation method of the modified silane cross-linking agent, the Karstedt catalyst is replaced by an equal amount of copper complex.

[0083] Performance testing

[0084] Polyethylene materials were prepared according to the methods in the embodiments and comparative examples, and the polyethylene materials were processed and formed to obtain cable sheath materials. Each sample was tested for crosslinking degree, tensile strength, elongation at break and dielectric strength. Three samples were taken from each embodiment and comparative example for testing, and the test results were averaged and recorded in Table 1. The testing method is as follows:

[0085] 1. Cross-linking degree: Take each sample and test it according to the test method of cross-linking degree of cross-linked polyethylene (PE-X) pipes and fittings in GB / T 18474-2001.

[0086] 2. Tensile strength and elongation at break: Take each sample and test it according to GB / T1040 Determination of tensile properties of plastics.

[0087] 3. Dielectric strength: Take each sample and test it according to GB / T1408.1 insulation material electrical strength test method.

[0088] Table 1

[0089]

[0090]

[0091] In combination with Examples 1-3, Comparative Example 1 and Table 1, the crosslinking degree of the polyethylene materials prepared by Examples 1-3 is better than that of the polyethylene material prepared by Comparative Example 1. The higher the crosslinking degree, the better the crosslinking effect of each component in the polyethylene material (especially the degree of silane grafting). It can be seen from the test results that the crosslinking strength of the modified silane crosslinker is better than that of the conventional unsaturated silane. Among them, the comprehensive performance of the polyethylene material prepared by Example 1 is the best.

[0092] In combination with Examples 1-3, Comparative Example 2 and Table 1, the dielectric strength of the polyethylene material prepared by Examples 1-3 is better than that of the polyethylene material prepared by Comparative Example 2. The higher the dielectric strength, the better the insulation performance of the polyethylene material, and the better the related electrical properties. It can be seen from the test results that although the voltage stability of the polyethylene material can be improved by mixing with inorganic nanofillers, its compatibility with polyolefin insulating materials is poor, and in the absence of an external dispersant, the inorganic nanoparticles are prone to agglomeration and are difficult to disperse, resulting in a further reduction in its voltage stabilization effect.

[0093] In combination with Examples 1-3, Comparative Example 3 and Table 1, the crosslinking degree of the polyethylene materials prepared by Examples 1-3 is better than that of the polyethylene materials prepared by Comparative Example 3, and the dielectric strength of the polyethylene materials prepared by Examples 1-3 is better than that of the polyethylene materials prepared by Comparative Example 3. It can be seen from the test results that the catalytic effect of the tin catalyst is not good, and the tin catalyst is highly toxic to the environment and the human body.

[0094] Combining Examples 1-3, Comparative Example 4 and Table 1, the crosslinking degree of the polyethylene materials prepared by Examples 1-3 is better than that of the polyethylene material prepared by Comparative Example 4. It can be seen from the test results that dibenzoyl peroxide has a better initiation effect, which may be due to the high decomposition temperature required for dicumyl peroxide, which is not conducive to controlling the possible reactions in the system and thermal decomposition at a lower temperature.

[0095] Combining Examples 1-3, Comparative Example 5 and Table 1, the crosslinking degree of the polyethylene materials prepared by Examples 1-3 is better than that of the polyethylene material prepared by Comparative Example 5. It can be seen from the test results that the compatibility of hindered phenol antioxidants in the reaction system is poor.

[0096] Combining Examples 1-3, Comparative Example 6 and Table 1, the crosslinking degree of the polyethylene materials prepared by Examples 1-3 is better than that of the polyethylene material prepared by Comparative Example 6. It can be seen from the test results that the Karstedt catalyst has a better effect on the catalytic addition reaction of the modified silane crosslinker, and the reaction cost of the Karstedt catalyst is low.

[0097] Combining Example 1, Example 4, Example 5 and Table 1, the comprehensive properties of the polyethylene material prepared by Example 1 are better than those of the polyethylene materials prepared by Example 4 and Example 5. It can be seen from the test results that the addition amount of each raw material and the reaction conditions in the preparation process of the modified silane crosslinking agent have peak values ​​within the set range. After changing the reaction conditions or the addition amount of the material is close to the end value, the yield will be affected.

[0098] Combining Example 1 with Example 6, Example 7, Example 8 and Table 1, the comprehensive performance of the polyethylene material prepared by Example 1 is better than that of the polyethylene material prepared by Example 6, Example 7 and Example 8. It can be seen from the test results that in the preparation process of the modified silane crosslinker, boron trifluoride is used for free radical copolymerization to make the main chain molecule have a highly electron-deficient characteristic, thereby improving the crosslinking activity of the reaction intermediate, promoting the mutual combination of the polyethylene main body and other additives and quickly completing the crosslinking transformation; and then using the Karstedt catalyst to reduce the activation energy required for the reaction to promote the speed and progress of the reaction; at the same time, divinylbenzene also has a crosslinking effect.

[0099] Combining Example 1, Examples 9-10 and Table 1, the crosslinking degree of the polyethylene material prepared by Example 1 is better than that of the polyethylene material prepared by Examples 9-10. It can be seen from the test results that the titanate catalyst and dibenzoyl peroxide initiator have a great influence on the speed and degree of the reaction.

[0100] In combination with Example 1, Example 11, Example 12 and Table 1, the tensile strength and elongation at break of the polyethylene material prepared by Example 1 are better than those of the polyethylene materials prepared by Examples 11 and 12. The higher the tensile strength and elongation at break, the better the physical and mechanical properties (such as elasticity, ductility, etc.) of the polyethylene material. It can be seen from the test results that Example 11 is poor in tensile strength and dielectric strength (because carbon black and mica powder also have certain insulation properties and can increase the resistivity of the polyethylene material) because the reinforcing agent formed by compounding carbon black and mica powder is not added (because carbon black and mica powder also have certain insulation properties and can increase the resistivity of the polyethylene material). Example 12 does not add an elastomer, that is, ethylene propylene diene monomer rubber particles, which leads to a significant reduction in the tensile strength of the prepared polyethylene material. The reason is that the ethylene propylene diene monomer rubber particles can provide material elasticity and ductility in addition to the polyethylene main body.

[0101] Combining Example 1, Example 14 and Table 1, the dielectric strength of the polyethylene material prepared in Example 1 is better than that of the polyethylene material prepared in Example 14. The test results show that the use of benzophenone derivatives as stabilizers can suppress the space charge generated when the polyethylene material is molded and sleeved with a DC cable, capture high-energy electrons in the insulating material under a strong electric field, and improve the breakdown strength of the material, thereby stabilizing the voltage.

[0102] 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. A silane cross-linked polyethylene material, characterized in that: The invention comprises the following components in parts by weight: 240-300 parts of polyethylene composite resin, 20-28 parts of modified silane crosslinking agent, 12-16 parts of stabilizer, 10-16 parts of initiator, 12-14 parts of antioxidant, 20-24 parts of catalyst, 50-70 parts of reinforcing agent, 26-30 parts of elastomer, 6-8 parts of water absorbent and 60-70 parts of auxiliary agent carrier; The modified silane crosslinking agent comprises the following components in parts by weight: 40-56 parts of dimethylchlorosilane, 18-24 parts of boron trifluoride, 46-50 parts of 1,7-octadiene, 30-40 parts of divinylbenzene, and 20-28 parts of Karstedt catalyst; The preparation method of the modified silane crosslinking agent comprises the following steps: S1. Under nitrogen protection, 1,7-octadiene, boron trifluoride and Karstedt catalyst are mixed, the temperature is raised to 45-55° C., and the mixture is stirred and activated for 40-60 minutes to obtain a reaction base material; S2. Dimethylchlorosilane is added dropwise to the reaction base material in step S1 at a rate of 10-20 mL / min. After the addition is complete, divinylbenzene is added and mixed evenly. After the reaction is carried out at a constant temperature for 10-12 hours, the mixture is distilled under reduced pressure to obtain a modified silane crosslinking agent.

2. A silane cross-linked polyethylene material according to claim 1, characterized in that: The stabilizer includes 4-aminobenzophenone and 9,10-bis(4-methoxyphenyl)anthracene, and the mass ratio of the 4-aminobenzophenone to the 9,10-bis(4-methoxyphenyl)anthracene is 1:(0.30-0.50).

3. A silane cross-linked polyethylene material according to claim 1, characterized in that: The polyethylene composite resin comprises high-density polyethylene, linear low-density polyethylene and medium-density polyethylene, and the mass ratio of the high-density polyethylene, the linear low-density polyethylene and the medium-density polyethylene is 1:(0.50-1.20):(0.30-0.40).

4. The silane cross-linked polyethylene material according to claim 1, characterized in that: The initiator is dibenzoyl peroxide.

5. The silane cross-linked polyethylene material according to claim 1, characterized in that: The catalyst is one or more of isopropyl octyl triacyloxy titanate and isopropyl tristearate titanate.

6. The silane cross-linked polyethylene material according to claim 1, characterized in that: The reinforcing agent includes mica powder and carbon black, and the mass ratio of the mica powder to the carbon black is 1:(1.30-1.50); The elastomer is EPDM rubber particles, and the particle size of the EPDM rubber particles is 0.50-0.80 nm.

7. The silane cross-linked polyethylene material according to claim 1, characterized in that: The antioxidant is one or more of antioxidant 1010, antioxidant 168 and antioxidant DLTP; The water absorbing agent is one or more of magnesium chloride, calcium chloride and aluminum chloride; The auxiliary agent carrier is one or more of ethylene-vinyl acetate copolymer, ethylene vinyl acetate copolymer and ethylene acrylic acid copolymer.

8. A method for preparing a silane cross-linked polyethylene material according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. A polyethylene composite resin accounting for 80-85% of the total amount is vacuum dried, heated to 110-130° C., a modified silane crosslinking agent, a catalyst and an initiator are added and mixed, the temperature is raised to 160-220° C., and a reinforcing agent and an elastomer pretreated with a mass fraction of 70-80% ethanol solution are added and mixed and stirred at a speed of 200-500 r / min to obtain a silane grafted material; S2. Control the temperature at 70-80°C, add antioxidant, stabilizer, water absorbent and auxiliary agent carrier to the remaining polyethylene composite resin, mix and stir at a speed of 100-300r / min to obtain an auxiliary agent masterbatch, heat to 150-200°C, add the auxiliary agent masterbatch to the silane grafted material, mix and stir at a speed of 500-700r / min, extrude and granulate, and obtain the silane cross-linked polyethylene material.

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