Insulating material composition, insulating material and method of preparation and use

Abstract

The application relates to the technical field of insulating materials, and discloses an insulating material composition, an insulating material, a preparation method and application.The composition comprises a base polypropylene, an elastomer fiber and an antioxidant; the elastomer fiber is selected from styrene-ethylene-butylene-styrene block copolymer and / or polyurethane copolymer; the tensile strength of the elastomer fiber is greater than or equal to 10 MPa, the elongation at break is greater than or equal to 400%, and the embrittlement temperature is less than or equal to -40 DEG C.The non-crosslinked polypropylene insulating cable material prepared by using the composition has good mechanical properties and electrical properties, high breakdown strength and small electric field distortion rate.

Description

Technical Field

[0001] This invention relates to the field of insulating materials technology, specifically to an insulating material composition, an insulating material, a preparation method thereon, and its applications. Background Technology

[0002] Currently, cross-linked polyethylene (XLPE) insulated cables are the main type of power transmission and distribution cables used in China. Compared with traditional thermosetting cross-linked polyethylene insulated cables, thermoplastic polypropylene insulated cables have advantages such as no cross-linking required in the production process, short production cycle, high transmission capacity, and recyclability. They can not only solve the environmental problem of difficult recycling of XLPE cable materials, but also reduce energy consumption and emissions in the cable production process and improve cable production efficiency.

[0003] Currently, domestic research institutions and cable manufacturers have also conducted basic research on thermoplastic cables. For example, CN117106258A discloses a polypropylene insulation material for high-voltage cables, its preparation method, and its application. The raw materials of the polypropylene insulation material for high-voltage cables, by weight, include 30-60 parts of polypropylene autoclave resin, 40-70 parts of thermoplastic polyolefin elastomer, and 0.3-1 parts of antioxidant. The thermoplastic polyolefin elastomer includes one or more of ethylene-octene copolymer, polyethylene, ethylene and vinyl acetate copolymer, polypropylene, and ethylene propylene rubber, which enables the polypropylene insulation cable material for high-voltage cables to have both excellent heat resistance and toughness.

[0004] However, the breakdown strength of existing non-crosslinked cable insulation materials decreases after being modified by elastomer blending, and electric field distortion is also caused. Summary of the Invention

[0005] This invention addresses the problems of decreased breakdown strength and increased electric field distortion rate in existing non-crosslinked polypropylene cable insulation materials after elastomer modification, by providing an insulation material composition, an insulation material, a preparation method, and its application.

[0006] To achieve the above objectives, a first aspect of the present invention provides an insulating material composition comprising: a matrix polypropylene, elastomer fibers, and an antioxidant; The elastomer fiber is selected from styrene-ethylene-butene-styrene block copolymers and / or polyurethane copolymers; The elastomer fiber has a tensile strength ≥10MPa, an elongation at break ≥400%, and an embrittlement temperature ≤-40℃.

[0007] A second aspect of the present invention provides a method for preparing an insulating material, the method comprising: melting and mixing the insulating material composition described in the first aspect, followed by extrusion, filtration and granulation to obtain the insulating material.

[0008] A third aspect of the present invention provides an insulating material prepared by the preparation method described in the second aspect above.

[0009] The fourth aspect of the present invention provides the application of the insulating material composition described in the first aspect or the insulating material described in the third aspect in a cable.

[0010] The insulating material composition provided by the present invention includes a matrix polypropylene, specific elastomer fibers and antioxidants, which can realize the blending modification of polypropylene with specific elastomer fibers. The non-crosslinked polypropylene insulated cable material prepared by the composition has good mechanical and electrical properties, high breakdown strength and low electric field distortion rate. Detailed Implementation

[0011] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0012] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0013] The first aspect of the present invention provides an insulating material composition comprising: a matrix polypropylene, elastomer fibers, and an antioxidant; The elastomer fiber is selected from styrene-ethylene-butene-styrene block copolymers and / or polyurethane copolymers; The elastomer fiber has a tensile strength ≥10MPa, an elongation at break ≥400%, and an embrittlement temperature ≤-40℃.

[0014] According to the present invention, in the insulating material composition, the matrix polypropylene is preferably an impact-resistant polypropylene with excellent impact resistance, which can bring excellent impact resistance and toughness to the insulating material.

[0015] According to the present invention, in the insulating material composition, preferably, the matrix polypropylene has a flexural modulus of 500-1000 MPa at 23°C, which can bring good flexibility to the insulating material.

[0016] According to the present invention, in the insulating material composition, preferably, the matrix polypropylene has a melt index of 1-3 g / 10 min at 230°C and 2.16 kg load, which helps to reduce the dimensional changes and deformation of the insulating material during processing, thereby maintaining the stability of the cable structure.

[0017] According to the present invention, in the insulating material composition, preferably, the matrix polypropylene has a volume resistivity ≥1×10⁻⁶ at 90°C. 14 Ω·cm can bring excellent electrical insulation properties to insulating materials.

[0018] According to the present invention, in the insulating material composition, preferably, the matrix polypropylene has a melting point of 140-167°C, which can bring excellent heat resistance to the insulating material.

[0019] According to the present invention, in the insulating material composition, preferably, the matrix polypropylene has a density of 0.9-0.93 g / cm³ at 23°C. 3 .

[0020] According to the present invention, in the insulating material composition, the matrix polypropylene can satisfy at least one of the above-mentioned flexural modulus, melt index, volume resistivity, melting point, and density indicators. Preferably, the matrix polypropylene simultaneously satisfies the above indicators, which enables the insulating material to possess excellent toughness, heat resistance, and electrical insulation properties.

[0021] In this invention, the flexural modulus of the matrix polypropylene is determined according to the method specified in GB / T 9341-2000.

[0022] In this invention, the melt index of the matrix polypropylene is determined according to the method specified in GB / T 3682.1-2018.

[0023] In this invention, the volume resistivity of the matrix polypropylene is determined according to the method specified in GB / T 31838.3-2019.

[0024] In this invention, the melting point of the matrix polypropylene is determined according to the method specified in GB / T 19466.3-2004.

[0025] In this invention, the density of the matrix polypropylene refers to the weight (g) of the non-permeable portion of the material per cubic centimeter at 23°C, and is determined using the method specified in GB / T 1033.1-2008.

[0026] According to the present invention, in the insulating material composition, the elastomeric fiber satisfies the following requirements: tensile strength ≥10MPa, elongation at break ≥400%, and embrittlement temperature ≤-40℃. By using this specific elastomeric fiber to blend and modify the matrix polypropylene, the problem of phase separation caused by the incompatibility of the two-phase interface between the matrix phase and the elastomeric phase can be improved, thereby enabling the prepared insulating material to have higher breakdown strength and lower electric field distortion rate.

[0027] According to the present invention, in the insulating material composition, the elastomer fiber is selected from styrene-ethylene-butene-styrene block copolymer and / or polyurethane copolymer, preferably styrene-ethylene-butene-styrene block copolymer, which enables the insulating material to have higher breakdown strength and lower electric field distortion rate, while also enabling the insulating material to have better low-temperature toughness.

[0028] According to the present invention, in the insulating material composition, for the styrene-ethylene-butene-styrene block copolymer, it is preferable that the embrittlement temperature of the styrene-ethylene-butene-styrene block copolymer is ≤-60°C, which is beneficial to improving the low-temperature toughness of the modified matrix polypropylene. More preferably, the embrittlement temperature of the styrene-ethylene-butene-styrene block copolymer is -70 to -60°C.

[0029] According to the present invention, in the insulating material composition, the styrene-ethylene-butene-styrene block copolymer is preferably used at a temperature ≤155°C, which is beneficial for the modified matrix polypropylene to maintain excellent heat resistance while possessing good processability. More preferably, the styrene-ethylene-butene-styrene block copolymer is used at a temperature of 140-150°C.

[0030] According to the present invention, in the insulating material composition, the styrene-ethylene-butene-styrene block copolymer preferably has a decomposition temperature ≥270°C in an oxygen atmosphere, which is beneficial for the modified matrix polypropylene to have excellent high-temperature resistance and long-term stability. More preferably, the styrene-ethylene-butene-styrene block copolymer has a decomposition temperature of 270-350°C in an oxygen atmosphere.

[0031] According to the present invention, in the insulating material composition, the content of styrene structural units in the styrene-ethylene-butene-styrene block copolymer is preferably 10-30% by weight, and the content of (ethylene structural units + butene structural units) is 70-90% by weight, which is beneficial to improving the low-temperature toughness of the modified matrix polypropylene.

[0032] According to the present invention, more preferably, the styrene-ethylene-butene-styrene block copolymer contains 10-20% by weight of styrene structural units and 80-90% by weight of (ethylene structural units + butene structural units).

[0033] According to the present invention, the styrene-ethylene-butene-styrene block copolymer can satisfy at least one of the above-mentioned embrittlement temperature, service temperature, and decomposition temperature in an oxygen atmosphere. Preferably, the styrene-ethylene-butene-styrene block copolymer simultaneously satisfies the above-mentioned indicators, thereby enabling the insulating material to have high breakdown strength, low electric field distortion rate, better low-temperature toughness, and good processability.

[0034] In this invention, the embrittlement temperature of the styrene-ethylene-butene-styrene block copolymer is determined according to the method specified in GB / T 5470-2008.

[0035] In this invention, the service temperature of the styrene-ethylene-butene-styrene block copolymer refers to the highest temperature that the material can continuously and stably withstand under the service conditions, as determined by the method specified in ASTM E831-2019.

[0036] In this invention, the decomposition temperature of the styrene-ethylene-butene-styrene block copolymer under an oxygen atmosphere was determined according to the method specified in ASTM E1131-20.

[0037] According to the present invention, in the insulating material composition, the polyurethane copolymer preferably contains polyether soft segments and diisocyanate hard segments, which can give the polyurethane copolymer better flexibility and low-temperature performance.

[0038] In this invention, preferably, the polyether soft segment content in the polyurethane copolymer is 30-50% by weight.

[0039] According to the present invention, in the insulating material composition, the softening temperature of the polyurethane copolymer is preferably ≥150°C, which can provide the insulating material with good heat resistance and maintain good insulation performance even at high ambient temperatures. More preferably, the softening temperature of the polyurethane copolymer is 150-180°C.

[0040] According to the present invention, in the insulating material composition, the polyurethane copolymer preferably has a tensile strength of 10-30 MPa, which can bring good mechanical strength to the insulating material. More preferably, the tensile strength of the polyurethane copolymer is 20-30 MPa.

[0041] According to the present invention, in the insulating material composition, the elongation at break of the polyurethane copolymer is preferably ≥400%, which is beneficial to improving the toughness of the modified matrix polypropylene. More preferably, the elongation at break of the polyurethane copolymer is preferably 400-600%.

[0042] According to the present invention, the polyurethane copolymer can satisfy at least one of the above-mentioned softening temperature, tensile strength, and elongation at break. Preferably, the polyurethane copolymer simultaneously satisfies the above-mentioned indicators, thereby enabling the insulating material to have high breakdown strength, low electric field distortion rate, and also better toughness and heat resistance.

[0043] In this invention, the softening temperature of the polyurethane copolymer is determined according to the method specified in ASTM E831-2019.

[0044] In this invention, the tensile strength of the polyurethane copolymer was determined according to the method specified in GB / T 1040.3-2006.

[0045] In this invention, the elongation at break of the polyurethane copolymer was determined according to the method specified in GB / T 1040.3-2006.

[0046] According to the present invention, in the insulating material composition, the elastomer is in the form of fibers, which can significantly improve the phase interface separation problem between the matrix and the elastomer phases. Compared with elastomers using conventional morphologies (non-fiber forms), it can significantly improve the problems of decreased breakdown strength and increased electric field distortion rate of the insulating material after blending modification.

[0047] According to the present invention, preferably, the elastomeric fiber has an average diameter of 80-120 μm and an average length of 20-50 mm.

[0048] More preferably, the average diameter of the elastomer fiber is 80-100 μm and the average length is 30-50 mm.

[0049] According to the present invention, the antioxidant in the insulating material composition is broadly defined, and conventional antioxidants used in the field of cable insulation materials can be selected. Preferably, the antioxidant is a compound antioxidant, including a primary antioxidant and a secondary antioxidant; wherein, preferably, the weight ratio of the primary antioxidant to the secondary antioxidant is 1:(1-4).

[0050] According to the present invention, in the insulating material composition, preferably, the main antioxidant is a thiobisphenol antioxidant.

[0051] According to the present invention, preferably, the melting point of the primary antioxidant is 161-164°C.

[0052] According to the present invention, preferably, the bulk density of the primary antioxidant is 1.06-1.12 g / cm³. 3 .

[0053] According to the present invention, preferably, the ash content of the main antioxidant is ≤0.5%.

[0054] According to some preferred embodiments of the present invention, the primary antioxidant may be 4,4'-thiobis(3-methyl-6-tert-butylphenol).

[0055] According to the present invention, in the insulating material composition, preferably, the auxiliary antioxidant is a phosphite antioxidant.

[0056] According to the present invention, preferably, the melting point of the auxiliary antioxidant is 183-187°C.

[0057] According to the present invention, preferably, the bulk density of the auxiliary antioxidant is 0.48-0.57 g / cm³. 3 .

[0058] According to the present invention, preferably, the ash content of the auxiliary antioxidant is ≤0.5%.

[0059] According to some preferred embodiments of the present invention, the co-antioxidant may be tris[2,4-di-tert-butylphenyl] phosphite.

[0060] According to the present invention, in the insulating material composition, in addition to satisfying the above-mentioned material selection, the elastomer fiber is 5-40 parts by weight relative to 60-95 parts by weight of the matrix polypropylene, and the antioxidant is 0.2-0.4 parts by weight, which is more conducive to obtaining an insulating material with higher breakdown strength and lower electric field distortion rate.

[0061] According to the present invention, preferably, in the insulating material composition, the elastomer fiber is 5-20 parts by weight relative to 60-95 parts by weight of the matrix polypropylene, and the antioxidant is 0.2-0.3 parts by weight.

[0062] According to a preferred embodiment of the present invention, in the composition, the matrix polypropylene has a flexural modulus of 500-1000 MPa at 23°C, a melt index of 2.5-3 g / 10 min at 230°C and a load of 2.16 kg, and a volume resistivity ≥1×10⁻⁶ at 90°C. 14 Ω·cm, melting point 150-167℃, density 0.9-0.93 g / cm³ 3The elastomer fiber is a styrene-ethylene-butene-styrene block copolymer fiber with an embrittlement temperature of -65 to -60°C, a service temperature of 145-150°C, and a decomposition temperature of 270-300°C in an oxygen atmosphere. The styrene structural unit content is 10-20% by weight, and the (ethylene structural unit + butene structural unit) content is 80-90% by weight. The average diameter of the elastomer fiber is 80-100 μm, and the average fiber length is 40-50 mm. The antioxidant is 4,4'-thiobis(3-methyl-6-tert-butylphenol) and tris[2,4-di-tert-butylphenyl]phosphite (4,4'-thiobis(3-methyl-6-tert-butylphenol):tris[2, The weight ratio of 4-di-tert-butylphenyl]phosphite is 1:1-2); the elastomer fiber is 5-20 parts by weight relative to 60-95 parts by weight of the matrix polypropylene, and the antioxidant is 0.2-0.3 parts by weight.

[0063] A second aspect of the present invention provides a method for preparing an insulating material, the method comprising: melting and mixing the insulating material composition described in the first aspect, followed by extrusion, filtration and granulation to obtain the insulating material.

[0064] According to the present invention, the method for preparing the insulating material has a relatively broad definition regarding the melt mixing process, and conventional equipment and melt mixing conditions in the art can be used. For example, the melt mixing can be carried out in a twin-screw extruder. Preferably, the melt mixing temperature is 160-200°C. Preferably, the melt mixing speed is 40-60 rpm.

[0065] According to the present invention, there is no particular limitation on the order of feeding the components in the insulating material composition for melt mixing, and any feeding order can be used. According to a preferred embodiment of the present invention, the primary antioxidant and the secondary antioxidant can be premixed to obtain a uniform compound antioxidant, and the matrix polypropylene, elastomer fiber and compound antioxidant can be mixed and melt-mixed, followed by extrusion granulation to obtain the insulating material.

[0066] According to the present invention, in the above preparation process, preferably, the premixing conditions include: being carried out at 25-40°C and a stirring rate of 80-100 rpm.

[0067] According to the present invention, in the method for preparing the insulating material, preferably, the filtration can be performed using a filter screen. Preferably, a filter screen with a pore size of 28-75 μm is used.

[0068] According to the present invention, the granulation method in the preparation method of the insulating material has a wide range of limitations, and conventional granulation methods can be used, preferably water-stretched pelletizing.

[0069] The method for preparing insulating materials provided by the present invention uses the insulating material composition provided by the present invention as raw material, and utilizes the specific elastomer fibers in the composition to blend and modify the matrix polypropylene, so that the prepared insulating material has good mechanical and electrical properties, high breakdown strength, and low electric field distortion rate.

[0070] A third aspect of the present invention provides an insulating material prepared by the preparation method described in the second aspect above.

[0071] According to the present invention, the insulating material has good mechanical properties and can improve the shortcomings of conventional polypropylene insulating materials, such as high rigidity and poor toughness.

[0072] According to the present invention, preferably, the tensile strength of the insulating material is 25-35 MPa.

[0073] In this invention, the tensile strength of the insulating material is determined according to the method specified in GB / T 1040.3-2006.

[0074] According to the present invention, preferably, the elongation at break of the insulating material is 325-620%.

[0075] In this invention, the elongation at break of the insulating material is determined according to the method specified in GB / T 1040.3-2006.

[0076] According to the present invention, the insulating material has good electrical properties.

[0077] According to the present invention, preferably, the volume resistivity of the insulating material is (3.6-10.5)×10⁻⁶. 14 Ω·m.

[0078] In this invention, the volume resistivity of the insulating material is determined according to the method specified in GB / T31838.3-2019, the test temperature is (25±2)℃, the test field strength is 20kV / mm, and the thickness of the test piece is (0.2±0.01)mm.

[0079] According to the present invention, preferably, the DC breakdown strength of the insulating material is 285-410 kV / mm; In this invention, the DC breakdown strength of the insulating material is determined according to the method specified in GB / T 1408.2-2016, with a test temperature of (25±2)℃ and a test piece thickness of (0.2±0.01)mm.

[0080] According to the present invention, preferably, the electric field distortion rate of the insulating material is 0.2-1.7%.

[0081] In this invention, the electric field distortion rate is determined according to the method specified in GB / T 1408.2-2016.

[0082] The insulating material provided by this invention is a non-crosslinked polypropylene insulating material, which has good mechanical and electrical properties, especially high breakdown strength and low electric field distortion rate, and can better meet the performance requirements of power transmission cables and distribution cables for insulating materials.

[0083] The fourth aspect of the present invention provides the application of the insulating material composition described in the first aspect or the insulating material described in the third aspect in a cable.

[0084] The present invention will be described in detail below through embodiments. In the following embodiments and comparative examples, Impact-resistant polypropylene: Model K8003, purchased from Maoming Petrochemical. This impact-resistant propylene has a flexural modulus of 1000 MPa at 23°C, a melt index of 2.53 g / 10 min at 230°C and a load of 2.16 kg, and a volume resistivity of 4 × 10⁻⁶ at 90°C. 14 It has a density of Ω·cm, a melting point of 165℃, and a density of 0.91 g / cm³ at 23℃. 3 .

[0085] Antioxidant 4,4'-thiobis(3-methyl-6-tert-butylphenol): melting point 162℃, bulk density 1.08 g / cm³ 3 The ash content is 0.1% by weight.

[0086] Antioxidant tris[2,4-di-tert-butylphenyl]phosphite: melting point 183℃, bulk density 0.49 g / cm³ 3 The ash content is 0.15% by weight.

[0087] Unless otherwise specified, all other materials used are common commercially available products.

[0088] Example 1 Insulating material composition (denoted as A1): the above-mentioned impact-resistant polypropylene, elastomer fibers (average diameter 100 μm, average length 40 mm), and antioxidant (4,4'-thiobis(3-methyl-6-tert-butylphenol): tris[2,4-di-tert-butylphenyl]phosphite in a weight ratio of 1:1). The elastomer fiber is a styrene-ethylene-butene-styrene block copolymer (embrittlement temperature -65℃, service temperature 145℃, decomposition temperature in oxygen atmosphere 270℃, the styrene structural unit content in the copolymer is 13% by weight, the sum of the ethylene structural unit and the butene structural unit content is 87% by weight, the manufacturer is Kraton, USA). Impact-resistant polypropylene, elastomer fiber: the weight ratio of compound antioxidant is 95:5:0.3.

[0089] The process for preparing insulating materials using the above-mentioned insulating material composition is as follows: S1: The 4,4'-thiobis(3-methyl-6-tert-butylphenol) and tris[2,4-di-tert-butylphenyl]phosphite in the above composition are stirred and premixed at 25°C and a stirring speed of 80 rpm to obtain a uniform compound antioxidant. S2: The impact-resistant polypropylene, elastomer fiber and compound antioxidant in the above composition are mixed and added to a mixer (the mixer temperature is 200℃). Then it is fed into a single screw extruder and melt-mixed in zones 1 (180℃), 2 (185℃), 3 (190℃), 4 (195℃), 5 (200℃) and 6 (200℃) at a speed of 60 rpm. Then it is filtered through a filter screen with a pore size of 28μm and finally water-stretched into pellets to obtain non-crosslinked polypropylene cable insulation material (denoted as S1).

[0090] Example 2 Insulating material composition (denoted as A2): the above-mentioned impact-resistant polypropylene, elastomer fibers (average diameter 80 μm, average length 50 mm), and antioxidant (4,4'-thiobis(3-methyl-6-tert-butylphenol): tris[2,4-di-tert-butylphenyl]phosphite in a weight ratio of 1:1). The elastomer fiber is a styrene-ethylene-butene-styrene block copolymer (embrittlement temperature -65℃, service temperature 145℃, decomposition temperature in oxygen atmosphere 270℃, the styrene structural unit content in the copolymer is 13% by weight, the sum of the ethylene structural unit and the butene structural unit content is 87% by weight, the manufacturer is Kraton, USA). Impact-resistant polypropylene, elastomer fiber: the weight ratio of compound antioxidant is 90:10:0.3.

[0091] Using the above-mentioned insulating material composition, an insulating material was prepared using the same steps and conditions as in Example 1 to obtain a non-crosslinked polypropylene cable insulating material (denoted as S2).

[0092] Example 3 Insulating material composition (denoted as A3): the above-mentioned impact-resistant polypropylene, elastomer fibers (average diameter 80 μm, average length 50 mm), and antioxidant (4,4'-thiobis(3-methyl-6-tert-butylphenol): tris[2,4-di-tert-butylphenyl]phosphite in a weight ratio of 1:1). The elastomer fiber is a styrene-ethylene-butene-styrene block copolymer (embrittlement temperature -65℃, service temperature 145℃, decomposition temperature in oxygen atmosphere 270℃). The copolymer contains 13% by weight of styrene structural units and 87% by weight of ethylene and butene structural units. The manufacturer is Kraton (USA). Impact-resistant polypropylene, elastomer fiber: the weight ratio of compound antioxidant is 70:30:0.3.

[0093] Using the above-described insulating material composition, an insulating material was prepared using the same steps and conditions as in Example 1 to obtain a non-crosslinked polypropylene cable insulating material (denoted as S3).

[0094] Example 4 Insulating material composition (denoted as A4): the above-mentioned impact-resistant polypropylene, elastomer fibers (average diameter 120 μm, average length 20 mm) and antioxidant (4,4'-thiobis(3-methyl-6-tert-butylphenol): tris[2,4-di-tert-butylphenyl]phosphite in a weight ratio of 1:1). The elastomer fiber is a styrene-ethylene-butene-styrene block copolymer (embrittlement temperature -65℃, service temperature 145℃, decomposition temperature in oxygen atmosphere 270℃, the styrene structural unit content in the copolymer is 13% by weight, the sum of the ethylene structural unit and the butene structural unit content is 87% by weight, the manufacturer is Kraton, USA). Impact-resistant polypropylene, elastomer fiber: the weight ratio of compound antioxidant is 90:10:0.3.

[0095] Using the above-described insulating material composition, an insulating material was prepared using the same steps and conditions as in Example 1 to obtain a non-crosslinked polypropylene cable insulating material (denoted as S4).

[0096] Example 5 Insulating material composition (denoted as A5): the above-mentioned impact-resistant polypropylene, elastomer fibers (average diameter 80 μm, average length 50 mm), and antioxidant (4,4'-thiobis(3-methyl-6-tert-butylphenol): tris[2,4-di-tert-butylphenyl]phosphite in a weight ratio of 1:1). The elastomer fiber is a styrene-ethylene-butene-styrene block copolymer (embrittlement temperature of -60℃, service temperature of 148℃, decomposition temperature of 290℃ in oxygen atmosphere, the styrene structural unit content in the copolymer is 30% by weight, the sum of the ethylene structural unit and the butene structural unit content is 70% by weight, and the manufacturer is Kraton, USA). Impact-resistant polypropylene, elastomer fiber: the weight ratio of compound antioxidant is 90:10:0.3.

[0097] Using the above-described insulating material composition, an insulating material was prepared using the same steps and conditions as in Example 1 to obtain a non-crosslinked polypropylene cable insulating material (denoted as S5).

[0098] Example 6 Insulating material composition (denoted as A6): the above-mentioned impact-resistant polypropylene, elastomer fibers (average diameter 120 μm, average length 20 mm) and antioxidant (4,4'-thiobis(3-methyl-6-tert-butylphenol): tris[2,4-di-tert-butylphenyl]phosphite in a weight ratio of 1:1). The elastomer fiber is a polyurethane copolymer (brand name PU71DID, manufacturer: Taiwan Hongyi, softening temperature: 150℃, tensile strength: 30MPa, elongation at break: 600%). This copolymer contains polyether soft segments and diisocyanate hard segments, with the content of polyether soft segments being 35% by weight. Impact-resistant polypropylene, elastomer fiber: the weight ratio of compound antioxidant is 90:10:0.3.

[0099] Using the above-described insulating material composition, an insulating material was prepared using the same steps and conditions as in Example 1 to obtain a non-crosslinked polypropylene cable insulating material (denoted as S6).

[0100] Example 7 Insulating material composition (denoted as A7): the above-mentioned impact-resistant polypropylene, elastomer fibers (average diameter 120 μm, average length 20 mm) and antioxidant (4,4'-thiobis(3-methyl-6-tert-butylphenol): tris[2,4-di-tert-butylphenyl]phosphite in a weight ratio of 1:1). The elastomer fiber is a styrene-ethylene-butene-styrene block copolymer (embrittlement temperature -58℃, service temperature 150℃, decomposition temperature in oxygen atmosphere 300℃, the styrene structural unit content in the copolymer is 33% by weight, the sum of the ethylene structural unit and the butene structural unit content is 67% by weight, the manufacturer is Kraton, USA). Impact-resistant polypropylene, elastomer fiber: the weight ratio of compound antioxidant is 90:10:0.3.

[0101] Using the above-described insulating material composition, an insulating material was prepared using the same steps and conditions as in Example 1 to obtain a non-crosslinked polypropylene cable insulating material (denoted as S7).

[0102] Example 8 Insulating material composition (denoted as A8): the above-mentioned impact-resistant polypropylene, elastomer fibers (average diameter 120 μm, average length 20 mm) and antioxidant (4,4'-thiobis(3-methyl-6-tert-butylphenol): tris[2,4-di-tert-butylphenyl]phosphite in a weight ratio of 1:1). The elastomer fiber is a styrene-ethylene-butene-styrene block copolymer (embrittlement temperature -65℃, service temperature 145℃, decomposition temperature in oxygen atmosphere 270℃, the styrene structural unit content in the copolymer is 13% by weight, the sum of the ethylene structural unit and the butene structural unit content is 87% by weight, the manufacturer is Kraton, USA). Impact-resistant polypropylene, elastomer fiber: the weight ratio of compound antioxidant is 55:45:0.3.

[0103] Using the above-mentioned insulating material composition, an insulating material was prepared using the same steps and conditions as in Example 1 to obtain a non-crosslinked polypropylene cable insulating material (denoted as S8).

[0104] Example 9 Insulating material composition (denoted as A9): the above-mentioned impact-resistant polypropylene, elastomer fibers (average diameter 140 μm, average length 80 mm) and antioxidant (4,4'-thiobis(3-methyl-6-tert-butylphenol): tris[2,4-di-tert-butylphenyl]phosphite in a weight ratio of 1:1). The elastomer fiber is a styrene-ethylene-butene-styrene block copolymer (embrittlement temperature -65℃, service temperature 145℃, decomposition temperature in oxygen atmosphere 270℃, styrene structural unit content in the copolymer is 13% by weight, (ethylene structural unit + butene structural unit) content is 87% by weight, manufacturer is Kraton, USA). Impact-resistant polypropylene, elastomer fiber: the weight ratio of compound antioxidant is 90:10:0.3.

[0105] Using the above-described insulating material composition, an insulating material was prepared using the same steps and conditions as in Example 1 to obtain a non-crosslinked polypropylene cable insulating material (denoted as S9).

[0106] Comparative Example 1 Insulating material composition (denoted as DA1): the above-mentioned impact-resistant polypropylene, elastomer (powder) and antioxidant (4,4'-thiobis(3-methyl-6-tert-butylphenol): tris[2,4-di-tert-butylphenyl]phosphite in a weight ratio of 1:1); The elastomer is a styrene-ethylene-butene-styrene block copolymer (embrittlement temperature of -65℃, service temperature of 145℃, decomposition temperature of 270℃ in oxygen atmosphere, the styrene structural unit content in the copolymer is 13% by weight, the sum of the ethylene structural unit and the butene structural unit content is 87% by weight, and the manufacturer is Kraton, USA). Impact-resistant polypropylene, elastomer (powder): the weight ratio of compounded antioxidant is 90:10:0.3.

[0107] Using the above-described insulating material composition, an insulating material was prepared using the same steps and conditions as in Example 1 to obtain a non-crosslinked polypropylene cable insulating material (denoted as DS1).

[0108] Comparative Example 2 The insulating material composition (denoted as DA2) consists of the above-mentioned impact-resistant polypropylene, elastomer fibers (average diameter 120 μm, average length 20 mm), and antioxidant (4,4'-thiobis(3-methyl-6-tert-butylphenol):tris[2,4-di-tert-butylphenyl]phosphite in a weight ratio of 1:1); wherein the elastomer fibers are ethylene-octene copolymers (manufactured by Dow Chemical). Impact-resistant polypropylene, elastomer fiber: the weight ratio of compound antioxidant is 90:10:0.3.

[0109] Using the above-described insulating material composition, an insulating material was prepared using the same steps and conditions as in Example 1 to obtain a non-crosslinked polypropylene cable insulating material (denoted as DS2).

[0110] Test case The non-crosslinked polypropylene cable insulation materials S1-S9 and DS1-DS2 prepared in Examples 1-9 and Comparative Examples 1-2 were hot-pressed using a flat vulcanizing machine (pre-pressed at 200°C for 5 min, and then pressurized at 200°C and 15 MPa for 20 min) to obtain circular sheet samples with a radius of 15 mm and a thickness of 0.2 mm. The mechanical and electrical properties of the samples were tested, and the results are shown in Table 1.

[0111] Tensile strength: determined according to the method specified in GB / T 1040.3-2006.

[0112] Elongation at break: determined according to the method specified in GB / T 1040.3-2006.

[0113] Volume resistivity: determined according to the method specified in GB / T 31838.3-2019, with a test temperature of 25℃, a test field strength of 20kV / mm, and a test piece thickness of 0.2mm.

[0114] DC breakdown strength: determined according to the method specified in GB / T 1408.2-2016, with a test temperature of 25℃ and a test piece thickness of 0.2mm.

[0115] Electric field distortion rate: determined according to the method specified in GB / T 1408.2-2016.

[0116] Table 1

[0117] As can be seen from the test results in Table 1, the specific elastomer fibers in the insulating material composition provided by the present invention are blended and modified with the matrix polypropylene, which can overcome the problems of decreased breakdown strength and increased electric field distortion rate after traditional elastomer blending modification. The DC breakdown strength of the prepared non-crosslinked polypropylene insulated cable material is higher than 290kV / mm, while the electric field distortion rate is lower than 2.3%, which can achieve both good mechanical and electrical properties.

[0118] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An insulating material composition, characterized in that, The composition comprises: a matrix polypropylene, elastomer fibers, and an antioxidant; The elastomer fiber is selected from styrene-ethylene-butene-styrene block copolymers and / or polyurethane copolymers; The tensile strength of the elastomer fiber is ≥10MPa, the elongation at break is ≥400%, and the embrittlement temperature is ≤-40℃.

2. The insulating material composition according to claim 1, wherein, The matrix polypropylene has a flexural modulus of 500-1000 MPa at 23°C. And / or, the melt index of the matrix polypropylene at 230°C and 2.16 kg load is 1-3 g / 10 min; And / or, the volume resistivity of the matrix polypropylene at 90°C is ≥1×10⁻⁶. 14 Ω·cm; And / or, the melting point of the matrix polypropylene is 140-167°C; And / or, the density of the matrix polypropylene is 0.9-0.93 g / cm³. 3 .

3. The insulating material composition according to claim 1 or 2, wherein, The embrittlement temperature of the styrene-ethylene-butene-styrene block copolymer is ≤-60℃; And / or, the service temperature of the styrene-ethylene-butene-styrene block copolymer is ≤155°C; And / or, the styrene-ethylene-butene-styrene block copolymer has a decomposition temperature ≥270°C in an oxygen atmosphere; And / or, the styrene-ethylene-butene-styrene block copolymer contains 10-30% by weight of styrene structural units and 70-90% by weight of (ethylene structural units + butene structural units).

4. The insulating material composition according to claim 3, wherein, The embrittlement temperature of the styrene-ethylene-butene-styrene block copolymer is -70 to -60°C; And / or, the styrene-ethylene-butene-styrene block copolymer is used at a temperature of 140-150°C; And / or, the styrene-ethylene-butene-styrene block copolymer has a decomposition temperature of 270-350°C in an oxygen atmosphere; And / or, the styrene-ethylene-butene-styrene block copolymer contains 10-20% by weight of styrene structural units and 80-90% by weight of (ethylene structural units + butene structural units).

5. The insulating material composition according to claim 1 or 2, wherein, The polyurethane copolymer contains polyether soft segments and diisocyanate hard segments; And / or, the softening temperature of the polyurethane copolymer is ≥150°C; And / or, the tensile strength of the polyurethane copolymer is 10-30 MPa; And / or, the elongation at break of the polyurethane copolymer is ≥400%.

6. The insulating material composition according to claim 5, wherein, The polyether soft segment content in the polyurethane copolymer is 30-50% by weight. And / or, the softening temperature of the polyurethane copolymer is 150-180°C; And / or, the tensile strength of the polyurethane copolymer is 20-30 MPa; And / or, the elongation at break of the polyurethane copolymer is 400-600%.

7. The insulating material composition according to claim 1 or 2, wherein, The elastomer fibers have an average diameter of 80-120 μm and an average length of 20-50 mm.

8. The insulating material composition according to claim 1 or 2, wherein, The antioxidant includes a primary antioxidant and a secondary antioxidant; wherein the weight ratio of the primary antioxidant to the secondary antioxidant is 1:(1-4).

9. The insulating material composition according to claim 8, wherein, The primary antioxidant is a thiobisphenol antioxidant. And / or, the melting point of the primary antioxidant is 161-164°C; And / or, the bulk density of the primary antioxidant is 1.06-1.12 g / cm³. 3 ; And / or, the ash content of the primary antioxidant is ≤0.5% by weight; And / or, the auxiliary antioxidant is a phosphite antioxidant; And / or, the melting point of the auxiliary antioxidant is 183-187°C; And / or, the bulk density of the auxiliary antioxidant is 0.48-0.57 g / cm³. 3 ; And / or, the ash content of the auxiliary antioxidant is ≤0.5% by weight.

10. The insulating material composition according to claim 1 or 2, wherein, The elastomer fiber comprises 5-40 parts by weight relative to 60-95 parts by weight of the matrix polypropylene, and the antioxidant comprises 0.2-0.4 parts by weight.

11. A method for preparing an insulating material, characterized in that, The method includes: melting and mixing the insulating material composition according to any one of claims 1-10, followed by extrusion, filtration and granulation to obtain the insulating material.

12. The preparation method according to claim 11, wherein, The temperature for the melt mixing is 160-200℃; And / or, the rotation speed of the melt mixing is 40-60 rpm.

13. An insulating material prepared by the preparation method according to claim 11 or 12.

14. The insulating material according to claim 11, wherein, The volume resistivity of the insulating material is (3.6-10.5)×10. 14 Ω·m; And / or, the tensile strength of the insulating material is 25-35 MPa; And / or, the elongation at break of the insulating material is 325-620%; And / or, the DC breakdown strength of the insulating material is 285-410 kV / mm; And / or, the electric field distortion rate of the insulating material is 0.2-1.7%.

15. The use of the insulating material composition according to any one of claims 1-10 or the insulating material according to claim 13 or 14 in a cable.

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