Insulating material as well as preparation method and application thereof

Abstract

The invention relates to an insulating material as well as a preparation method and application thereof. The insulating material is prepared from the following raw materials in parts by mass: 30 to 50 parts of co-polypropylene, 5 to 25 parts of heat-resistant polypropylene, 30 to 50 parts of polyolefin thermoplastic elastomer and 0.2 to 0.4 part of antioxidant. According to the invention, copolymerized polypropylene, heat-resistant polypropylene, polyolefin thermoplastic elastomer and antioxidant interact and synergistically interact under specific components and proportions, so that the technical problem that toughness and heat resistance are difficult to consider when polypropylene is used in the field of insulating materials for high-voltage cables is solved; the prepared insulating material has high heat resistance, high mechanical toughness and excellent electrical strength, avoids the phenomena of softening, deformation or cracking of the insulating layer due to heating, and meets the material requirements of high-voltage cables.

Description

Technical Field

[0001] The present application relates to the technical field of composite materials, and in particular to an insulating material and a preparation method and application thereof. Background Art

[0002] In the field of power transmission, the performance of cables directly affects the operating efficiency, safety and reliability of the power system. Among traditional cables, cross-linked polyethylene (XLPE) insulated high-voltage cables are widely used in long-distance and large-span transmission lines due to their excellent electrical properties and durability. They are also the preferred material for high-voltage power transmission systems due to their high capacity, high reliability and maintenance-free advantages. However, cross-linked polyethylene produces by-products during the cross-linking process, which not only increases production costs but also prolongs the production cycle. In addition, these by-products produced during the cross-linking process may affect the electrical insulation properties of the cable, thereby limiting the transmission capacity of the cable. Moreover, the recycling of cross-linked polyethylene materials is difficult, which poses a challenge to environmental protection and the sustainable use of resources.

[0003] In contrast, polypropylene (PP), as a non-polar polymer material, exhibits many advantages that cross-linked polyethylene does not have. First, polypropylene material has good recyclability, which helps to reduce environmental pollution and resource waste, and is low in cost. In addition, polypropylene also has excellent insulation properties and high heat resistance, which is suitable for high-voltage cable insulation materials. Therefore, polypropylene high-voltage cable insulation materials are regarded as a potential alternative material that can effectively overcome the defects of cross-linked polyethylene cables and provide a more environmentally friendly and economical solution for future power transmission systems. However, the use of polypropylene in the field of high-voltage cable insulation materials has technical difficulties in balancing toughness and heat resistance, because in order to improve the toughness of the insulation material, a large amount of elastic material needs to be introduced, which will reduce the heat resistance of the insulation material, and then cause the high-voltage cable insulation layer to soften, deform or crack. Summary of the invention

[0004] Based on this, it is necessary to provide an insulating material having both high heat resistance and high toughness, and a preparation method and application thereof.

[0005] In the first aspect of the present application, an insulating material is provided, wherein the raw materials for preparing the insulating material include the following components in parts by weight: 30 to 50 parts of copolymerized polypropylene, 5 to 25 parts of heat-resistant polypropylene, 30 to 50 parts of polyolefin thermoplastic elastomer and 0.2 to 0.4 parts of antioxidant.

[0006] The raw materials for preparing the insulating material of the present application introduce heat-resistant polypropylene on the basis of copolymer polypropylene base material, and are compounded with polyolefin thermoplastic elastomer at the same time. The heat-resistant polypropylene provides a heat-resistant crystal skeleton, and then forms a complete crystal structure with other components in the insulating material. The crystal structure effectively terminates the expansion of silver streaks and shear bands at the interface of the insulating material, improves the heat resistance and gives the insulating material excellent mechanical toughness. The copolymer polypropylene, heat-resistant polypropylene, polyolefin thermoplastic elastomer and antioxidant interact with each other and synergize under specific components and ratios, which solves the technical problem that it is difficult to balance toughness and heat resistance when using polypropylene in the field of high-voltage cable insulation materials. The obtained insulating material has high heat resistance, high mechanical toughness and excellent electrical strength, which meets the material requirements of high-voltage cables.

[0007] The insulating material of the present application adopts a polyolefin thermoplastic elastomer. The longer olefin chain segments in the polyolefin thermoplastic elastomer increase the free volume of the chain segment movement, thereby enhancing the toughness of the insulating material. In addition, the polyolefin thermoplastic elastomer has good compatibility with the copolymerized polypropylene base material, further improving the stability and toughness of the insulating material in terms of mechanical properties.

[0008] During the actual use of high-voltage cables, even if the insulating material of the present application is operated under load for a long time and the cable is affected by heat and the temperature is too high, the thermal deformation of the insulating material is small, thus avoiding the softening, deformation or cracking of the insulating layer due to heat, thereby greatly extending the service life of the cable.

[0009] In some embodiments, the copolymerized polypropylene is 35 to 45 parts, the heat-resistant polypropylene is 15 to 25 parts, the polyolefin thermoplastic elastomer is 35 to 45 parts, and the antioxidant is 0.2 to 0.4 parts.

[0010] In some embodiments, the polyolefin thermoplastic elastomer is a copolymer of ethylene and propylene, the weight content of ethylene in the polyolefin thermoplastic elastomer is 10% to 13%, and the polyolefin thermoplastic elastomer is an isotactic polymer.

[0011] In some embodiments, the polyolefin thermoplastic elastomer has a melt flow rate of 1.0 g / 10 min to 2.8 g / 10 min at a temperature of 230° C. and a load of 2.16 kg.

[0012] In some embodiments, the heat-resistant polypropylene has a melt flow rate of 2.8 g / 10 min to 3.8 g / 10 min at a temperature of 230° C. and a load of 2.16 kg.

[0013] In some embodiments, the molecular chain stereoregularity of the heat-resistant polypropylene is ≥96%.

[0014] In some embodiments, the copolymerized polypropylene has a melt flow rate of 1.0 g / 10 min to 2.0 g / 10 min at a temperature of 230° C. and a load of 2.16 kg, and a weight average molecular weight of 2.5×10 5 g / mol~5.4×10 5 g / mol.

[0015] In some embodiments, the copolymerized polypropylene includes a polypropylene phase and a rubber phase, the polypropylene phase is a continuous phase, and the rubber phase is an ethylene-propylene random copolymer;

[0016] Wherein, the weight content of the rubber phase in the copolymerized polypropylene is 30% to 40%, and / or the particle size distribution range of the rubber phase is 0.4 μm to 1 μm.

[0017] In some embodiments, the molecular chain stereoregularity of the copolymerized polypropylene is 50% to 70%.

[0018] The second aspect of the present application provides a method for preparing the insulating material as described in the first aspect, wherein the copolymerized polypropylene, the heat-resistant polypropylene, the polyolefin thermoplastic elastomer and the antioxidant are melt-blended according to the composition of the preparation raw materials to obtain the insulating material.

[0019] In some embodiments, the melt blending temperature is 180°C to 220°C.

[0020] The third aspect of the present application provides an insulating product, comprising the insulating material as described in the first aspect and the insulating material prepared by the preparation method as described in the second aspect.

[0021] A fourth aspect of the present application provides a high-voltage cable, comprising the insulating material as described in the first aspect and the insulating material prepared by the preparation method as described in the second aspect.

[0022] A fifth aspect of the present application provides an electrical device comprising the high voltage cable as described in the fourth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a bar graph of the tensile strength test results of Examples 1-4 and Comparative Examples 1-2.

[0024] Figure 2 It is a bar graph of the elongation at break test results of Examples 1-4 and Comparative Examples 1-2.

[0025] Figure 3 The figure is a bar graph showing the bending modulus test results of Examples 1 to 4 and Comparative Examples 1 to 2.

[0026] Figure 4 It is the AC breakdown Weibull distribution diagram of the breakdown field strength of Examples 1 to 4 and Comparative Examples 1 to 2. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0029] The quality of cable performance directly affects the safety, reliability and operating efficiency of the power system. Cross-linked polyethylene insulation materials are often used as insulation materials for traditional high-voltage cables, but the cross-linking by-products in the production process can easily affect the performance of the cable and increase production costs. In addition, cross-linked polyethylene insulation materials are difficult to recycle, which is not conducive to environmental protection and sustainable utilization of resources. Polypropylene not only has excellent insulation properties and high heat resistance, but also has low production costs and good recyclability. Therefore, researchers have tried to replace cross-linked polyethylene with polypropylene to overcome the defects of cross-linked polyethylene cables. However, in this process, in order to ensure the toughness of the insulating material, polypropylene needs to be mixed with a large amount of elastomers. The introduction of a large amount of elastomers has led to a decrease in the heat resistance of the insulating material, and there is a technical problem that it is difficult to balance heat resistance and toughness.

[0030] Based on this, in the first aspect of the present application, one embodiment provides an insulating material, the raw materials for preparing the insulating material include the following components in parts by mass: 30 to 50 parts of copolymerized polypropylene, 5 to 25 parts of heat-resistant polypropylene, 30 to 50 parts of polyolefin thermoplastic elastomer and 0.2 to 0.4 parts of antioxidant.

[0031] The raw materials for preparing the insulating material of the present application introduce heat-resistant polypropylene on the basis of copolymer polypropylene base material, and are compounded with polyolefin thermoplastic elastomer to form a perfect crystal structure in the insulating material. The crystal structure effectively terminates the expansion of silver streaks and shear bands at the interface of the insulating material, improves the heat resistance and gives the insulating material excellent mechanical toughness; copolymer polypropylene, heat-resistant polypropylene, polyolefin thermoplastic elastomer and antioxidant interact and synergize under specific components and ratios, solving the technical problem that it is difficult to balance toughness and heat resistance when using polypropylene in the field of high-voltage cable insulation materials. The obtained insulating material has high heat resistance, high mechanical toughness and excellent electrical strength, meeting the material requirements of high-voltage cables.

[0032] The insulating material of the present application adopts a polyolefin thermoplastic elastomer. The longer olefin chain segments in the polyolefin thermoplastic elastomer increase the free volume of the chain segment movement, thereby enhancing the toughness of the insulating material. In addition, the polyolefin thermoplastic elastomer has good compatibility with the copolymerized polypropylene base material, further improving the stability and toughness of the insulating material in terms of mechanical properties.

[0033] During the actual use of high-voltage cables, even if the insulating material of the present application is operated under load for a long time and the cable is affected by heat and the temperature is too high, the thermal deformation of the insulating material is small, thus avoiding the softening, deformation or cracking of the insulating layer due to heat, thereby greatly extending the service life of the cable.

[0034] As an example, the copolymerized polypropylene can be 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 37.5 parts, 38 parts, 39 parts, 40 parts, 41 parts, 42 parts, 42.5 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 47.5 parts, 48 ​​parts, 49 parts and 50 parts, or it can be within the range consisting of any two of the above point values ​​as end values, preferably 35 parts to 45 parts, and further can be 37 parts to 43 parts.

[0035] As an example, the heat-resistant polypropylene can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts and 25 parts, or it can be within the range consisting of any two of the above point values ​​as end values, preferably 15 parts to 25 parts.

[0036] As an example, the polyolefin thermoplastic elastomer can be 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 37.5 parts, 38 parts, 39 parts, 40 parts, 41 parts, 42 parts, 42.5 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 47.5 parts, 48 ​​parts, 49 parts and 50 parts, or it can be within the range consisting of any two of the above point values ​​as end values, preferably 35 to 45 parts, and more preferably 37 to 43 parts.

[0037] As an example, the antioxidant may be 0.2 parts, 0.25 parts, 0.3 parts, 0.3 parts and 0.4 parts, or may be within a range consisting of any two of the above points as end values, preferably 0.2 parts to 0.3 parts.

[0038] In some embodiments, the copolymerized polypropylene is 35 to 45 parts, the heat-resistant polypropylene is 15 to 25 parts, the polyolefin thermoplastic elastomer is 35 to 45 parts, and the antioxidant is 0.2 to 0.4 parts. Under this mass ratio of the components of the insulating material, the synergistic optimization of heat resistance, mechanical toughness and electrical properties is achieved, meeting the actual use requirements of polypropylene high-voltage cables, and the insulating layer will not soften, deform or crack under high temperature conditions.

[0039] In some embodiments, the polyolefin thermoplastic elastomer is a copolymer of ethylene and propylene, the weight content of ethylene in the polyolefin thermoplastic elastomer is 10% to 13%, and the polyolefin thermoplastic elastomer is an isotactic polymer. The longer olefin chain segments in the polyolefin thermoplastic elastomer formed by the copolymerization of ethylene and propylene increase the free volume of the chain segment movement, and the polyolefin thermoplastic elastomer with isotactic characteristics enhances the toughness of the insulating material; and the polyolefin thermoplastic elastomer has good compatibility with the copolymerized polypropylene base material, which further improves the stability and toughness of the insulating material in terms of mechanical properties, thereby reducing the amount of elastomer used and improving the heat resistance of the insulating material.

[0040] It is understood that the polyolefin thermoplastic elastomer is a single-phase structure.

[0041] As an example, the weight content of ethylene in the polyolefin thermoplastic elastomer can be 10%, 11%, 12%, and 13%, or can be in a range consisting of any two of the above point values ​​as end values, preferably 11% to 13%. When the weight content of ethylene in the polyolefin thermoplastic elastomer is 11% to 13%, the toughness and heat resistance of the insulating material are unexpectedly balanced, greatly improving the comprehensive performance of the insulating material.

[0042] In some embodiments, the polyolefin thermoplastic elastomer has a melt flow rate of 1.0 g / 10 min to 2.8 g / 10 min at a temperature of 230° C. and a load of 2.16 kg. The polyolefin thermoplastic elastomer at this melt flow rate enables the insulating material to have good processability and consistency, and further improves the toughness of the insulating material.

[0043] As an example, the melt flow rate of the polyolefin thermoplastic elastomer at a temperature of 230° C. and a load of 2.16 kg can be 1.0 g / 10 min, 1.1 g / 10 min, 1.2 g / 10 min, 1.3 g / 10 min, 1.4 g / 10 min, 1.5 g / 10 min, 1.6 g / 10 min, 1.7 g / 10 min, 1.8 g / 10 min, 1.9 g / 10 min, 2.0 g / 10 min, 2.1 g / 10 min, 2.2 g / 10 min, 2.3 g / 10 min, 2.4 g / 10 min, 2.5 g / 10 min, 2.6 g / 10 min, 2.7 g / 10 min, and 2.8 g / 10 min, or it can be within the range consisting of any two of the above point values ​​as end values, preferably 1.0 g / 10 min to 1.6 g / 10 min.

[0044] In some embodiments, the melt flow rate of the heat-resistant polypropylene at a temperature of 230°C and a load of 2.16 kg is 2.8 g / 10 min to 3.8 g / 10 min. The heat-resistant polypropylene used in the present application has good heat resistance itself, and its introduction into the insulating material can improve the heat resistance of the insulating material; in addition, the heat-resistant polypropylene is conducive to promoting the formation of a perfect crystal structure of the insulating material, thereby significantly improving the heat resistance of the insulating material. Furthermore, the structural similarity between the heat-resistant polypropylene and the copolymer polypropylene improves the compatibility between the material components, making the interior of the insulating material uniform and stable, thereby improving the toughness of the insulating material.

[0045] As an example, the melt flow rate of the heat-resistant polypropylene at a temperature of 230°C and a load of 2.16Kg is 2.8 g / 10min, 2.9 g / 10min, 3.0 g / 10min, 3.1 g / 10min, 3.2 g / 10min, 3.3 g / 10min, 3.4 g / 10min, 3.5 g / 10min, 3.6 g / 10min, 3.7 g / 10min, and 3.8 g / 10min, and can also be within the range consisting of any two of the above point values ​​as end values, preferably 3.0 g / 10min to 3.5 g / 10min.

[0046] In some embodiments, the molecular chain stereoregularity of the heat-resistant polypropylene is ≥ 96%. The highly regular molecular chain structure of the heat-resistant polypropylene is conducive to forming a perfect crystal structure, thereby improving the heat resistance of the insulation material.

[0047] As an example, the molecular chain stereoregularity of the heat-resistant polypropylene may be 96%, 97%, 98%, and 99%, or may be within a range consisting of any two of the above point values ​​as end values.

[0048] Furthermore, the molecular chain stereoregularity of the heat-resistant polypropylene is 96% to 98%.

[0049] In some embodiments, the copolymerized polypropylene has a melt flow rate of 1.0 g / 10 min to 2.0 g / 10 min at a temperature of 230° C. and a load of 2.16 kg, and a weight average molecular weight of 2.5×10 5 g / mol~5.4×10 5 When the copolymerized polypropylene at the melt flow rate is compounded with heat-resistant polypropylene and polyolefin thermoplastic elastomer, the insulating material can obtain better comprehensive properties such as heat resistance, toughness and electrical properties.

[0050] In some embodiments, the copolymerized polypropylene includes a polypropylene phase and a rubber phase, the polypropylene phase is a continuous phase, and the rubber phase is an ethylene-propylene random copolymer;

[0051] Wherein, the weight content of the rubber phase in the copolymerized polypropylene is 30% to 50%, and / or the particle size distribution range of the rubber phase is 0.4 μm to 1 μm.

[0052] It is understood that the copolymerized polypropylene has a two-phase structure.

[0053] As an example, the weight content of the rubber phase in the copolymerized polypropylene can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49% and 50%, or it can be within the range of any two of the above points as end values, preferably 30% to 40%, and more preferably 33% to 40%. When the weight content of the rubber phase in the copolymerized polypropylene is 30% to 40%, the crystal structure formed by the copolymerized polypropylene, the heat-resistant polypropylene and the polyolefin thermoplastic elastomer is more perfect, and the synergistic effect of improving the toughness and heat resistance of the material is more obvious.

[0054] In some embodiments, the polypropylene is a copolymerized polypropylene including a polypropylene phase and a rubber phase, the polypropylene phase is a continuous phase, and the rubber phase is an ethylene-propylene random copolymer;

[0055] Wherein, the weight content of the rubber phase in the copolymerized polypropylene is 30% to 40%, and / or the particle size distribution range of the rubber phase is 0.4μm to 1μm. When the copolymerized polypropylene with a rubber weight content of 30% to 40% and a rubber phase size of 0.4μm to 1μm is compounded with heat-resistant polypropylene and polyolefin thermoplastic elastomer, the insulating material can obtain better comprehensive properties such as heat resistance, toughness and electrical properties.

[0056] In some embodiments, the molecular chain stereoregularity of the copolymerized polypropylene is less than 90%.

[0057] In some embodiments, the molecular chain stereoregularity of the copolymerized polypropylene is 50% to 70%.

[0058] In some embodiments, the antioxidant includes one or more of antioxidant 1010 , antioxidant 168 , antioxidant 1076 , and antioxidant 626 .

[0059] The second aspect of the present application provides a method for preparing the insulating material as described in the first aspect, wherein the copolymerized polypropylene, the heat-resistant polypropylene, the polyolefin thermoplastic elastomer and the antioxidant are melt-blended according to the composition of the preparation raw materials to obtain the insulating material.

[0060] Furthermore, the mixing method of the melt blending is internal mixing or extrusion.

[0061] Furthermore, 30 to 50 parts of copolymerized polypropylene, 5 to 25 parts of heat-resistant polypropylene, 30 to 50 parts of polyolefin thermoplastic elastomer, and 0.2 to 0.4 parts of antioxidant are weighed as raw materials, placed in an internal mixer or an extruder for melt blending to obtain a polypropylene insulation material.

[0062] In some embodiments, the melt blending temperature is 180°C to 220°C, preferably 190°C to 200°C.

[0063] In some embodiments, the melt blending time is 5 min to 10 min.

[0064] In some of the embodiments, the rotation speed of the melt blending equipment is 80 r / min ~150 r / min.

[0065] The third aspect of the present application provides an insulating product, comprising the insulating material as described in the first aspect and the insulating material prepared by the preparation method as described in the second aspect.

[0066] A fourth aspect of the present application provides a high-voltage cable, comprising the insulating material as described in the first aspect and the insulating material prepared by the preparation method as described in the second aspect.

[0067] A fifth aspect of the present application provides an electrical device comprising the high voltage cable as described in the first aspect.

[0068] The following are specific embodiments.

[0069] Example 1

[0070] 47.5 parts of copolymerized polypropylene, 5 parts of heat-resistant polypropylene, 47.5 parts of polyolefin thermoplastic elastomer, and 0.2 parts of antioxidant were weighed as raw materials, placed in an internal mixer for melt blending, and a polypropylene-based insulating material was obtained.

[0071] The melt blending process is as follows: temperature 190°C, time 5 minutes, rotation speed 80 r / min;

[0072] The copolymerized polypropylene comprises a polypropylene phase and a rubber phase, wherein the polypropylene phase is a continuous phase, the rubber phase is an ethylene-propylene random copolymer, the weight content of the rubber phase in the copolymerized polypropylene is 33%, and the particle size distribution range of the rubber phase is 0.4 μm to 1 μm; the melt flow rate of the copolymerized polypropylene at a temperature of 230°C and a load of 2.16 kg is 1.6 g / 10 min, and the weight average molecular weight is 4.1×10 5 g / mol.

[0073] Heat-resistant polypropylene: Its molecular chain stereoregularity is 97.2%;

[0074] Polyolefin thermoplastic elastomer: it is a copolymer of ethylene and propylene, the weight content of ethylene in the polyolefin thermoplastic elastomer is 11%, and the polyolefin thermoplastic elastomer is an isotactic polymer; the melt flow rate of the polyolefin thermoplastic elastomer at a temperature of 230° C. and a load of 2.16 kg is 1.1 g / 10 min;

[0075] The antioxidant is antioxidant 1010.

[0076] Example 2

[0077] Example 2 is basically the same as Example 1, except that the raw materials for preparing the insulating material are 45 parts of copolymerized polypropylene, 10 parts of heat-resistant polypropylene, 45 parts of polyolefin thermoplastic elastomer, and 0.3 parts of antioxidant.

[0078] Example 3

[0079] Example 3 is basically the same as Example 1, except that the raw materials for preparing the insulating material are 42.5 parts of copolymerized polypropylene, 15 parts of heat-resistant polypropylene, 42.5 parts of polyolefin-based thermoplastic elastomer, and 0.3 parts of antioxidant.

[0080] Example 4

[0081] Example 4 is basically the same as Example 1, except that the raw materials for preparing the insulating material are 37.5 parts of copolymerized polypropylene, 25 parts of heat-resistant polypropylene, 37.5 parts of polyolefin thermoplastic elastomer, and 0.3 parts of antioxidant.

[0082] Example 5

[0083] Example 5 is substantially the same as Example 1, except that the weight content of ethylene in the polyolefin thermoplastic elastomer is 13%.

[0084] Example 6

[0085] Example 6 is basically the same as Example 1, except that the weight content of the rubber phase in the copolymerized polypropylene is 40%.

[0086] Comparative Example 1

[0087] Comparative Example 1 is substantially the same as Example 1, except that 50 parts of copolymerized polypropylene, 50 parts of polyolefin thermoplastic elastomer and 0.2 parts of antioxidant are used as raw materials.

[0088] Comparative Example 2

[0089] Comparative Example 2 is substantially the same as Example 1, except that 56 parts of copolymerized polypropylene, 20 parts of heat-resistant polypropylene, 24 parts of polyolefin thermoplastic elastomer, and 0.2 parts of antioxidant are used as raw materials.

[0090] Comparative Example 3

[0091] Comparative Example 3 is substantially the same as Example 1, except that the polyolefin thermoplastic elastomer is replaced by an equal mass fraction of styrene-based thermoplastic elastomer.

[0092] Comparative Example 4

[0093] Comparative Example 4 is substantially the same as Example 1, except that the amount of the polyolefin thermoplastic elastomer is 55 parts.

[0094] The insulating materials prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were tested for room temperature flexural modulus, breakdown field strength, elongation at break, tensile strength, elongation under load and permanent deformation. The test results of room temperature flexural modulus, breakdown field strength, elongation at break and tensile strength are shown in Table 1; the test results of elongation under load and permanent deformation (i.e., heat deformation resistance) of the insulating materials prepared in Examples 1 to 6 and Comparative Examples 1 to 4 are shown in Table 2.

[0095] The tensile strength test results of Examples 1 to 4 and Comparative Examples 1 to 2 are as follows: Figure 1 The elongation at break test results of Examples 1 to 4 and Comparative Examples 1 to 2 are shown in Figure 2 The bending modulus test results of Examples 1 to 4 and Comparative Examples 1 to 2 are shown in Figure 3 As shown; AC breakdown Weibull distribution diagram of breakdown field strength of Examples 1 to 4 and Comparative Examples 1 to 2 is shown Figure 4 shown.

[0096] Among them, the bending modulus and tensile properties are tested based on GB / T9341-2008 and GB / T 1040.1-2018 as standard requirements.

[0097] Thermal deformation resistance test: In order to evaluate whether the insulating material can maintain the necessary mechanical strength under the expected overload temperature, the sample is prepared according to the tensile performance test method. Based on the standard requirements of GB / T 2951.21-2008, the standard test method of thermal elongation test is adopted. One end of the sample is hung in an oven, the oven temperature is set to 150 ℃, and the other end is subjected to a weight converted to mass by applying a tensile force of 0.2 MPa according to the cross section of the sample. After the set time of 15 minutes, the elongation of the sample is measured, which is defined as the elongation under load. The elongation after cooling is defined as the permanent deformation rate.

[0098] Table 1

[0099]

[0100] Table 2

[0101]

[0102] As shown in Table 1 above, the tensile strength of the insulating material prepared in Comparative Example 1 is slightly more than 20MPa, and the elongation at break is close to 800%, but the permanent deformation rate under thermal extension is 14%, which does not meet the requirements of GB / T 11017.2-2014. In Example 1, after adding 5wt% of heat-resistant polypropylene, the permanent deformation rate under thermal extension is reduced to 4.00%, and the addition of heat-resistant polypropylene has a significant improvement effect on the high-temperature heat deformation performance; although Comparative Example 2 shows relatively excellent heat resistance, the bending modulus is 595.1MPa, the stiffness is relatively high, and the elongation at break is 483.7% (GB / T 11017.2-2014 requires <500%), which is difficult to meet the mechanical performance requirements of polypropylene cables. With the increase of the content of heat-resistant polypropylene, the bending modulus of Examples 1 to 4 gradually increases, the elongation at break gradually decreases, and the tensile strength is greatly improved compared with Comparative Example 1, and the three properties all meet the mechanical performance requirements of polypropylene cables. The ability of Examples 1 to 4 to resist thermal deformation has been greatly improved, especially Example 4 has almost no change after the thermal deformation test, and the heat resistance has been greatly improved, which can avoid the problems of cable heating, mechanical performance degradation, and shortened service life caused by high-voltage power transmission in actual use. Examples 5 and 6 increase the weight content of ethylene in the polyolefin thermoplastic elastomer and the weight content of the rubber phase in the copolymerized polypropylene, respectively, which can improve the mechanical toughness to a certain extent (the bending modulus decreases and the elongation at break increases), and the breakdown performance can still maintain a good level. However, the addition of the styrene-based thermoplastic elastomer in Comparative Example 3 has poor interfacial compatibility with the copolymerized polypropylene, thereby significantly reducing the mechanical properties. The content of the polyolefin thermoplastic elastomer in Comparative Example 4 is too high, which significantly changes the phase structure of the multiphase system, thereby greatly reducing the heat resistance of the system.

[0103] From the data in Table 1 and Figure 4 It can be seen that in the AC breakdown test, the corresponding field strength when the Weibull AC breakdown distribution probability is 63.2% is used as the characteristic breakdown field strength. After adding heat-resistant polypropylene, there is little effect on the AC breakdown field strength, which meets the requirements of polypropylene insulation materials.

[0104] Therefore, this application achieves the synergistic optimization of the heat deformation resistance, mechanical toughness and electrical properties of polypropylene insulation materials through the compound use of copolymerized polypropylene, heat-resistant polypropylene, polyolefin thermoplastic elastomer and antioxidant, meeting the requirements of polypropylene high-voltage cables.

[0105] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0106] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An insulating material, characterized in that: The raw materials for preparing the insulating material include the following components in parts by mass: 30 to 50 parts of copolymerized polypropylene, 5 to 25 parts of heat-resistant polypropylene, 30 to 50 parts of polyolefin thermoplastic elastomer and 0.2 to 0.4 parts of antioxidant.

2. The insulating material according to claim 1, characterized in that The copolymerized polypropylene accounts for 35 to 45 parts, the heat-resistant polypropylene accounts for 15 to 25 parts, the polyolefin thermoplastic elastomer accounts for 35 to 45 parts, and the antioxidant accounts for 0.2 to 0.4 parts.

3. The insulating material according to claim 1, characterized in that The polyolefin thermoplastic elastomer is a copolymer of ethylene and propylene, the weight content of the ethylene in the polyolefin thermoplastic elastomer is 10% to 13%, and the polyolefin thermoplastic elastomer is an isotactic polymer.

4. The insulating material according to claim 1, characterized in that The polyolefin thermoplastic elastomer has a melt flow rate of 1.0 g / 10min to 2.8 g / 10min at a temperature of 230° C. and a load of 2.16 kg.

5. The insulating material according to claim 1, characterized in that The melt flow rate of the heat-resistant polypropylene at a temperature of 230° C. and a load of 2.16 kg is 2.8 g / 10 min to 3.8 g / 10 min.

6. The insulating material according to claim 1, characterized in that The molecular chain stereoregularity of the heat-resistant polypropylene is ≥96%.

7. The insulating material according to any one of claims 1 to 6, characterized in that: The copolymerized polypropylene has a melt flow rate of 1.0 g / 10 min to 2.0 g / 10 min at a temperature of 230° C. and a load of 2.16 kg, and a weight average molecular weight of 2.5×10 5 g / mol~5.4×10 5 g / mol.

8. The insulating material according to any one of claims 1 to 6, characterized in that: The copolymerized polypropylene comprises a polypropylene phase and a rubber phase, wherein the polypropylene phase is a continuous phase and the rubber phase is an ethylene-propylene random copolymer; Wherein, the weight content of the rubber phase in the copolymerized polypropylene is 30% to 40%, and / or the particle size distribution range of the rubber phase is 0.4 μm to 1 μm.

9. The insulating material according to any one of claims 1 to 6, characterized in that: The molecular chain stereoregularity of the copolymerized polypropylene is 50% to 70%.

10. A method for preparing the insulating material according to any one of claims 1 to 9, characterized in that: The copolymerized polypropylene, the heat-resistant polypropylene, the polyolefin thermoplastic elastomer and the antioxidant are melt-blended according to the composition of the raw materials to obtain the insulating material.

11. The method for preparing an insulating material according to claim 10, characterized in that: The temperature of the melt blending is 180°C to 220°C.

12. An insulation product, characterized in that: The invention comprises the insulating material as claimed in any one of claims 1 to 9 and the insulating material obtained by the preparation method as claimed in claim 10 or 11.

13. A high voltage cable, characterized in that: The invention comprises the insulating material as claimed in any one of claims 1 to 9 and the insulating material obtained by the preparation method as claimed in claim 10 or 11.

14. An electrical device, characterized in that: Comprising the high voltage cable as claimed in claim 13.

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