CN115947895A - Thermoplastic polypropylene direct-current cable insulating material and preparation method thereof - Google Patents

Abstract

The application discloses a thermoplastic polypropylene direct current cable insulating material and a preparation method thereof, wherein the preparation raw materials of the thermoplastic polypropylene direct current cable insulating material comprise the following components: 100 parts of copolymerization modified polypropylene, 0.1-2 parts of additive with grafting group, anti-aging group and polar group, 0.1-1 part of initiator and 0.5-1 part of copper inhibitor. The additive containing polar groups is added into polypropylene, and is grafted to a polypropylene macromolecular chain through double bond groups in a molten state under the action of an initiator. The additive exists on a molecular chain, and cannot migrate, consume and the like to lose efficacy in the using process of the cable. Meanwhile, polar groups on the additive are uniformly dispersed in a polypropylene matrix, so that the distribution characteristics such as trap density and energy level of a polypropylene material can be effectively regulated and controlled, accumulation of space charges can be effectively inhibited under a direct-current electric field, and distortion of the electric field is prevented.

Description

Thermoplastic polypropylene direct-current cable insulating material and preparation method thereof

Technical Field

The application relates to the field of novel power transmission and distribution equipment, in particular to a thermoplastic polypropylene direct-current cable insulating material and a preparation method thereof.

Background

Crosslinked polyethylene (XLPE) has excellent mechanical and electrical properties and is the main insulating material for current extruded cables. However, in the production process of the XLPE cable, the energy consumption is high in the cross-linking and degassing process, the production efficiency is low, the decommissioned insulating material is difficult to recycle, and the environment pollution is caused by burning or landfill, so that the XLPE cable does not accord with the existing concept of energy conservation and environmental protection and the aim of double carbon. The non-crosslinked polypropylene material is selected as the cable insulation material, which is the trend towards green cables in the future. However, polypropylene is a thermoplastic material, and the molecular chain of polypropylene has tertiary carbon atoms which are easily oxidized, so that thermal oxidation aging is easily caused, and the mechanical property, the thermal stability and the electrical property of the material are influenced. Antioxidants 1010, 300, 1076, 1035 and the like used in general cable insulation materials are liable to migrate, precipitate, and lose in the thermoplastic polypropylene macromolecular chains, and the content thereof in the resin is reduced, resulting in a reduction in the antioxidant effect thereof. In addition, under the action of a direct current electric field, a large amount of space charges formed by electrode injection and ionization of additives or impurities such as antioxidants in the material can be accumulated in the material, so that the electric field in the material is distorted, the breakdown performance of the insulating material is obviously influenced, and the long-term reliability and the service life of the material are further influenced.

Disclosure of Invention

The application provides a thermoplastic polypropylene direct current cable insulation material and a preparation method thereof, which can effectively solve the problem that in the prior art, an antioxidant is gathered in an amorphous area and is easy to migrate and precipitate, so that the polypropylene insulation material is aged in an electric-thermal field, and the service life of a cable is influenced.

The following technical scheme is adopted in the application:

the application provides a thermoplastic polypropylene direct current cable insulating material, which comprises the following components in parts by weight: 100 parts of copolymerization modified polypropylene, 0.1-2 parts of additive with grafting group, anti-aging group and polar group, 0.1-1 part of initiator and 0.5-1 part of copper inhibitor.

Further, the grafting group comprises a double bond group, and the double bond group comprises one or a combination of several of vinyl, maleimide group and acryloyl group.

Further, the anti-aging group includes a hindered phenolic group and/or a hindered amine group.

Further, the polar group comprises one or a combination of more of hydroxyl, amido, carbonyl, benzene ring, ester group and amido.

Further, the additive comprises one or more of 2- (2-hydroxy-3-tert-butyl-5-methylbenzyl) -4-methyl-6-tert-butylphenyl acrylate, N- (4-anilinophenyl) methacrylamide, N- (4-anilinophenyl) maleimide, N- (3-methacryloyloxy-2-hydroxymethyl) -N' -phenyl-p-phenylenediamine, 2,4, 6-triallylphenol and 3, 5-di-tert-butyl-4-hydroxybenzyl acrylate.

Further, the copolymerization modified polypropylene comprises ethylene propylene copolymerization modified polypropylene, wherein the polypropylene is isotactic polypropylene or atactic polypropylene, the content of ethylene and propylene is 10-20%, and the melt index of the ethylene propylene copolymerization modified polypropylene is 2 +/-0.5 g/10min.

Further, the initiator comprises one or more of dicumyl peroxide, azobisisobutyronitrile and benzoyl peroxide.

Further, the copper-resistant agent includes N-salicylamidophthalimide.

The application also provides a preparation method of the thermoplastic polypropylene direct current cable insulating material, which comprises the following steps: adding the copolymerization modified polypropylene, the additive, the initiator and the copper resisting agent into a screw extruder for mixing and extrusion molding, and then carrying out water cooling and granulation to obtain the thermoplastic polypropylene direct current cable insulating material.

Furthermore, in the screw extruder, the temperature of each zone of the screw is 180-220 ℃, the rotating speed of a feed inlet is 10-16 rpm, and the rotating speed of the screw is 150-300 rpm.

Compared with the prior art, the method has the following beneficial effects:

the additive containing polar groups is added into polypropylene, and is grafted to a polypropylene macromolecular chain through double bond groups in a molten state under the action of an initiator. Compared with the prior art that the antioxidant exists in an amorphous area, can migrate under the action of an electric field and a temperature field, and the like, the additive exists on a molecular chain, and cannot migrate, consume and the like in the use process of the cable so as to lose efficacy. Meanwhile, polar groups on the additive are uniformly dispersed in a polypropylene matrix, so that the distribution characteristics such as trap density and energy level of a polypropylene material can be effectively regulated and controlled, the accumulation of space charges can be effectively inhibited under a direct-current electric field, and the distortion of the electric field is prevented.

Detailed Description

The technical method in the embodiments of the present application will be clearly and completely described below. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The application provides a thermoplastic polypropylene direct current cable insulating material, which comprises the following components in parts by weight: 100 parts by weight of copolymerization modified polypropylene, 0.1-2 parts by weight (such as 0.1 part by weight, 1 part by weight, 2 parts by weight) of additive with grafting group, anti-aging group and polar group, 0.1-1 part by weight (such as 0.1 part by weight, 0.5 part by weight, 1 part by weight) of initiator, and 0.5-1 part by weight (such as 0.5 part by weight, 0.8 part by weight, 1 part by weight) of copper-resistant agent.

The grafting group comprises a double bond group, the double bond group comprises one or a combination of several of vinyl, maleimide group and acryloyl group, for example, the grafting group is vinyl, and the grafting group is maleimide group and acryloyl group.

The anti-aging group comprises a hindered phenol group and/or a hindered amine group, for example, the anti-aging group is a hindered phenol group, and the anti-aging group is a hindered phenol group and a hindered amine group.

The polar group comprises one or more of hydroxyl, amido, carbonyl, benzene ring, ester group and amido, for example, the polar group is hydroxyl, and the polar group is amido and carbonyl.

The additive comprises one or more of 2- (2-hydroxy-3-tert-butyl-5-methylbenzyl) -4-methyl-6-tert-butylphenyl acrylate, N- (4-anilinophenyl) methacrylamide, N- (4-anilinophenyl) maleimide, N- (3-methacryloyloxy-2-hydroxymethyl) -N' -phenyl-p-phenylenediamine, 2,4, 6-triallylphenol and 3, 5-di-tert-butyl-4-hydroxybenzyl acrylate, for example, the additive is 2- (2-hydroxy-3-tert-butyl-5-methylbenzyl) -4-methyl-6-tert-butylphenyl acrylate, and the additive is 2,4, 6-triallylphenol and 3, 5-di-tert-butyl-4-hydroxybenzyl acrylate.

The copolymerization modified polypropylene comprises ethylene propylene copolymerization modified polypropylene, wherein the polypropylene is isotactic polypropylene or atactic polypropylene, the content of ethylene and propylene is 10-20 percent, such as 10 percent, 15 percent and 20 percent, and the melt index of the ethylene propylene copolymerization modified polypropylene is 2 +/-0.5 g/10min, such as 1.5g/10min, 2g/10min and 2.5g/10min.

The initiator comprises one or more of dicumyl peroxide, azobisisobutyronitrile and benzoyl peroxide. If the initiator is dicumyl peroxide, the initiator is azobisisobutyronitrile and benzoyl peroxide.

The copper-resistant agent comprises N-salicylamido phthalimide.

The application also provides a preparation method of the thermoplastic polypropylene direct current cable insulating material, which comprises the following steps: adding the copolymerization modified polypropylene, the additive, the initiator and the copper resisting agent into a double-screw extruder for mixing and extrusion molding, and then performing water cooling and granulation by a water tank to obtain the thermoplastic polypropylene direct current cable insulating material.

In the screw extruder, the temperature of each area of the screw is 180-220 ℃, the rotating speed of the feeding port is 10-16 rpm, and the rotating speed of the screw is 150-300 rpm.

The following is a detailed description with reference to specific examples:

example 1

The polypropylene is prepared from ethylene-propylene copolymerization modified polypropylene, wherein the content of ethylene-propylene is 17%, the melt index is 1.9g/10min, an initiator is dicumyl peroxide, an antioxidant is 2- (2-hydroxy-3-tert-butyl-5-methylbenzyl) -4-methyl-6-tert-butylphenyl acrylate, and a copper-resistant agent is N-salicylamido phthalimide.

Feeding 100 parts of ethylene-propylene copolymerization modified polypropylene into a double-screw extruder according to 1kg per part, mixing and extruding for molding, feeding 0.3 part of dicumyl peroxide, 0.2 part of 2- (2-hydroxy-3-tert-butyl-5-methylbenzyl) -4-methyl-6-tert-butylphenyl acrylate and 0.5 part of N-salicylamido-phthalimide into the double-screw extruder, wherein the heating temperature of the double-screw extruder is 195 ℃, the rotating speed of a screw is 300rpm, the rotating speed of a feeding port is 12rpm, and the molded granules are cooled by a water tank and then sent for granulation to obtain the thermoplastic polypropylene direct current cable insulating material.

Example 2

The content of ethylene and propylene in the ethylene-propylene copolymerization modified polypropylene is 15%, the melt index is 2.1g/10min, the initiator is azodiisobutyronitrile, the antioxidant is N- (4-anilinophenyl) methacrylamide, and the copper resisting agent is N-salicylamido phthalimide.

Feeding 100 parts of ethylene-propylene copolymerization modified polypropylene into a double-screw extruder according to 1kg per part, mixing and extruding for molding, feeding 0.5 part of azodiisobutyronitrile, 0.7 part of N- (4-anilinophenyl) methacrylamide and 0.7 part of N-salicylamido phthalimide into the double-screw extruder, wherein the heating temperature of the double-screw extruder is 180 ℃, the rotating speed of a screw is 200rpm, the rotating speed of a feeding port is 10rpm, and the molded granules are cooled by a water tank and then are fed for granulation to obtain the thermoplastic polypropylene direct current cable insulating material.

Example 3

The content of ethylene and propylene in the selected ethylene-propylene copolymerization modified polypropylene is 12 percent, the melt index is 2.4g/10min, the initiator is benzoyl peroxide, the antioxidant is N- (4-anilinophenyl) maleimide, and the copper resisting agent is N-salicylamido phthalimide.

Feeding 100 parts of ethylene-propylene copolymerization modified polypropylene into a double-screw extruder according to 1kg per part, mixing and extruding for molding, feeding 0.15 part of dicumyl peroxide, 0.6 part of N- (4-anilinophenyl) maleimide and 0.9 part of N-salicylamido phthalimide into the double-screw extruder, wherein the heating temperature of the double-screw extruder is 200 ℃, the rotating speed of a screw is 150rpm, the rotating speed of a feeding port is 12rpm, and the molded granules are cooled by a water tank and then sent for granulation to obtain the thermoplastic polypropylene direct-current cable insulating material.

Example 4

The content of ethylene and propylene in the selected ethylene-propylene copolymerization modified polypropylene is 10%, the melt index is 2.5g/10min, the initiator is dicumyl peroxide, the antioxidant is N- (3-methacryloyloxy-2-hydroxymethyl) -N' -phenyl-p-phenylenediamine, and the copper resisting agent is N-salicylamido phthalimide.

100 parts of ethylene propylene copolymerization modified polypropylene is fed into a double-screw extruder for mixing and extrusion molding according to 100g of each part, 0.8 part of dicumyl peroxide, 1.5 parts of N- (3-methacryloyloxy-2-hydroxymethyl) -N' -phenyl p-phenylenediamine and 0.6 part of N-salicylamido phthalimide are fed into the double-screw extruder, the heating temperature of the double-screw extruder is 220 ℃, the rotating speed of the screw is 240rpm, and granules formed by 15rpm of the rotating speed of a feed inlet are cooled by a water tank and then sent for granulation to obtain the thermoplastic polypropylene direct current cable insulating material.

Example 5

The content of ethylene and propylene in the ethylene-propylene copolymerization modified polypropylene is 20%, the melt index is 1.7g/10min, the initiator is azobisisobutyronitrile, the antioxidant is 2,4, 6-triallylphenol, and the copper resisting agent is N-salicylamido phthalimide.

100 parts of ethylene propylene copolymerization modified polypropylene is fed into a double-screw extruder for mixing and extrusion molding according to 100g of each part, 0.15 part of dicumyl peroxide, 0.2 part of 2,4, 6-triallyl phenol and 0.75 part of N-salicylamido phthalimide are fed into the double-screw extruder, the heating temperature of the double-screw extruder is 200 ℃, the rotating speed of the screw is 230rpm, the rotating speed of a feeding port is 14rpm, and molded granules are cooled by a water tank and then sent for granulation to obtain the thermoplastic polypropylene direct current cable insulating material.

Example 6

The content of ethylene and propylene in the selected ethylene-propylene copolymerization modified polypropylene is 16 percent, the melt index is 2.1g/10min, the initiator is benzoyl peroxide, the antioxidant is 3, 5-di-tert-butyl-4-hydroxybenzyl acrylate, and the copper resisting agent is N-salicylamido phthalimide.

100 parts of ethylene propylene copolymerization modified polypropylene is fed into a double-screw extruder for mixing and extrusion molding according to 100g of each part, 0.9 part of dicumyl peroxide, 2 parts of 2- (2-hydroxy-3-tert-butyl-5-methylbenzyl) -4-methyl-6-tert-butylphenyl acrylate and 1 part of N-salicylamido phthalimide are fed into the double-screw extruder, the heating temperature of the double-screw extruder is 215 ℃, the rotating speed of a screw is 270rpm, the rotating speed of a feeding port is 15rpm, and molded granules are cooled by a water tank and then are fed for granulation to obtain the thermoplastic polypropylene direct current cable insulating material.

Comparative example 1

Ethylene-propylene copolymerization modified polypropylene is selected, the content of ethylene and propylene is 16%, the melt index is 2.1g/10min, the antioxidant is 1010, and the copper-resistant agent is N-salicylamido phthalimide.

100g of each part of ethylene-propylene copolymerization modified polypropylene is fed into a double-screw extruder for mixing and extrusion molding, 0.5 part of antioxidant 1010 and 1 part of N-salicylamido phthalimide are fed into the double-screw extruder, the heating temperature of the double-screw extruder is 210 ℃, the rotating speed of a screw is 250rpm, the rotating speed of a feed inlet is 14rpm, and molded granules are cooled by a water tank and then are fed for granulation to obtain the thermoplastic polypropylene direct current cable insulating material.

Comparative example 2

Ethylene-propylene copolymerization modified polypropylene is selected, the content of ethylene and propylene is 15%, the melt index is 2.0g/10min, the antioxidant is 300, and the copper resisting agent is N-salicylamido phthalimide.

100g of each part of ethylene-propylene copolymerization modified polypropylene is fed into a double-screw extruder for mixing and extrusion molding, 0.6 part of antioxidant 300 and 0.8 part of N-salicylamido phthalimide are fed into the double-screw extruder, the heating temperature of the double-screw extruder is 195 ℃, the rotating speed of a screw is 220rpm, the rotating speed of a feed inlet is 12rpm, and molded granules are cooled by a water tank and then are fed for granulation to obtain the thermoplastic polypropylene direct-current cable insulating material.

The breakdown properties and thermal decomposition temperatures of the thermoplastic polypropylene direct current cable insulation of examples 1-6 and comparative examples 1-2 were examined and the results are shown in the following table:

semi-crystalline polymers are interpenetrating network structures consisting of entangled amorphous and crystalline phase structures. The antioxidant used by the cable material in the prior art exists in an amorphous area of a non-crosslinked polypropylene material, and is easy to migrate and consume under the action of an external electric field and a temperature field, so that the exertion effect of the antioxidant is weakened, the aging resistance and the insulating property of cable insulation are influenced, and the long-term service life of the cable is further influenced. According to the preparation method, the additive is adopted, and the antioxidant molecules containing polar groups are grafted to a polypropylene molecular chain through the initiator, so that on one hand, the internal current carriers of the material are effectively reduced, the trap density and energy level distribution of the material are improved, the direct current breakdown strength is improved, and the accumulation of space charges is reduced. On the other hand, the antioxidant molecules grafted on the molecular chain are not easy to migrate and separate out, so that the polypropylene insulating material has good heat resistance and aging resistance.

As can be seen from the data in the above table, the direct current breakdown strength of example 1 was 277kV/mm, the initial thermal decomposition temperature was 457 ℃, the direct current breakdown strength of example 2 was 268kV/mm, the initial thermal decomposition temperature was 455 ℃, the direct current breakdown strength of example 3 was 263kV/mm, the initial thermal decomposition temperature was 461 ℃, the direct current breakdown strength of example 4 was 270kV/mm, the initial thermal decomposition temperature was 453 ℃, the direct current breakdown strength of example 5 was 281kV/mm, the initial thermal decomposition temperature was 454 ℃, the direct current breakdown strength of example 6 was 274kV/mm, the initial thermal decomposition temperature was 460 ℃, the direct current breakdown strength of comparative example 1 was 227kV/mm, the initial thermal decomposition temperature was 430 ℃, the direct current breakdown strength of comparative example 2 was 223kV/mm, and the initial thermal decomposition temperature was 433 ℃. Compared with the thermoplastic polypropylene direct current cable insulation material in the prior art, the breakdown strength and the initial thermal decomposition temperature of the thermoplastic polypropylene direct current cable insulation material are both high. That is, the thermoplastic polypropylene direct current cable insulation material has high direct current breakdown strength and high thermal decomposition temperature resistance.

The foregoing shows and describes the general principles, essential features, and advantages of the application. It will be understood by those skilled in the art that the present application is not limited to the embodiments described above, which are included to illustrate the principles of the application and that various changes and modifications may be made without departing from the spirit and scope of the application, the scope of which is defined by the appended claims, specification and equivalents thereof.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present application and not for limiting the protection scope of the present application, and although the present application is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present application without departing from the spirit and scope of the technical solutions of the present application.

Claims (10)

1. The thermoplastic polypropylene direct current cable insulation material is characterized in that the preparation raw materials comprise the following components: 100 parts of copolymerization modified polypropylene, 0.1-2 parts of additive with grafting group, anti-aging group and polar group, 0.1-1 part of initiator and 0.5-1 part of copper inhibitor.

2. The thermoplastic polypropylene direct current cable insulation of claim 1,

the grafting group comprises a double bond group, and the double bond group comprises one or a combination of several of vinyl, maleimide group and acryloyl group.

3. The thermoplastic polypropylene direct current cable insulation of claim 1,

the anti-aging group comprises a hindered phenolic group and/or a hindered amine group.

4. The thermoplastic polypropylene direct current cable insulation of claim 1,

the polar group comprises one or a combination of more of hydroxyl, amido, carbonyl, benzene ring, ester group and amide group.

5. The thermoplastic polypropylene direct current cable insulation of claim 1,

the additive comprises one or a combination of more of 2- (2-hydroxy-3-tert-butyl-5-methylbenzyl) -4-methyl-6-tert-butylphenyl acrylate, N- (4-anilinophenyl) methacrylamide, N- (4-anilinophenyl) maleimide, N- (3-methacryloyloxy-2-hydroxymethyl) -N' -phenyl-p-phenylenediamine, 2,4, 6-triallylphenol and 3, 5-di-tert-butyl-4-hydroxybenzyl acrylate.

6. The thermoplastic polypropylene direct current cable insulation of claim 1,

the copolymerization modified polypropylene comprises ethylene propylene copolymerization modified polypropylene, wherein the ethylene propylene copolymerization modified polypropylene is isotactic polypropylene or atactic polypropylene, the content of ethylene propylene is 10-20%, and the melt index of the ethylene propylene copolymerization modified polypropylene is 2 +/-0.5 g/10min.

7. The thermoplastic polypropylene direct current cable insulation of claim 1,

the initiator comprises one or a combination of more of dicumyl peroxide, azobisisobutyronitrile and benzoyl peroxide.

8. The thermoplastic polypropylene direct current cable insulation of claim 1,

the copper resistant agent comprises N-salicylamido phthalimide.

9. A method for preparing the thermoplastic polypropylene direct current cable insulation according to any one of claims 1 to 8, comprising the steps of:

adding the copolymerization modified polypropylene, the additive, the initiator and the copper resisting agent into a screw extruder for mixing and extrusion molding, and then carrying out water cooling and granulation to obtain the thermoplastic polypropylene direct current cable insulating material.

10. The method according to claim 9,

in the screw extruder, the temperature of each area of the screw is 180-220 ℃, the rotating speed of the feeding port is 10-16 rpm, and the rotating speed of the screw is 150-300 rpm.