Thermoplastic semiconductive shielding material as well as preparation method and application thereof

Abstract

The invention discloses a propenyl copolymer resin matrix, the propenyl copolymer resin matrix is prepared from hydroxylated propenyl copolymer resin, polyisocyanate, a polyol oligomer and a chain extender, and the hydroxyl content in the hydroxylated propenyl copolymer resin is 0.2-3 mol%. The propenyl copolymer resin matrix structure prepared by the invention comprises a polar chain segment and a flexible chain segment, has excellent mechanical properties, compatibility, dispersion performance and processability, especially has an ultra-dispersion effect on conductive filler particles, reduces the accumulation of the conductive filler particles, improves the performance of a semiconductive shielding material, and has a good application prospect. The polypropylene insulating material has good compatibility with polypropylene insulating materials, can be better matched with a polypropylene insulating layer, reduces injection and accumulation of space charges, has good hot working performance, can be recycled, and can be widely applied to polypropylene insulating cables.

Description

Technical Field

[0001] The present invention relates to the technical field of cable materials, and particularly relates to a thermoplastic semiconductive shielding material, a preparation method thereof, and an application thereof. Background Art

[0002] A power cable consists of multiple layers such as a metal conductor, inner and outer semiconductive shielding layers, an insulating layer, and a sheath. The main function of the semiconductive shielding layer is to eliminate the air gap between the insulating layer and the conductor or the metal shielding layer during the installation and operation of the cable, evenly distribute the electric field strength on the conductor surface, slow down the multi-filament effect, and improve the partial discharge phenomenon. The performance of the semiconductive shielding layer will greatly affect the service life of the cable. Currently, the base resins of the semiconductive shielding layer materials used in widely used cross-linked polyethylene (XLPE) cables include ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-butyl acrylate copolymer (EBA), etc. A semiconductive shielding material can be made by mixing different amounts of carbon black and cross-linking agent with the base resin. However, its application scenarios have limitations. For example, in thermoplastic insulated cables represented by polypropylene (PP) insulation, the semiconductive shielding materials of cross-linked polyethylene cables cannot be applied to PP insulated cables because the processing temperature of PP insulation is above 170°C. At this temperature, the initiator will initiate a cross-linking reaction, making it impossible for the shielding material to be extruded smoothly. Currently, there are few studies and reports on semiconductive shielding materials suitable for PP insulation. Therefore, it is necessary to develop a cross-linking agent-free semiconductive shielding material suitable for the manufacture of PP insulated power cables, which is expected to break through the development bottleneck of ultra-high voltage cable insulation technology and is an important direction for the development of power cable technology. Summary of the Invention

[0003] Based on this, it is necessary to provide a propylene-based copolymer resin matrix with good mechanical properties, compatibility, and dispersibility, and its application in thermoplastic semiconductive shielding materials.

[0004] In a first aspect, the present invention provides a propylene-based copolymer resin matrix, which is prepared by a hydroxylated propylene-based copolymer resin, a polyisocyanate, a polyol oligomer, and a chain extender. The hydroxyl content in the hydroxylated propylene-based copolymer resin is 0.2 - 3 mol%.

[0005] In some embodiments, the propylene-based copolymer resin matrix satisfies at least one of the following (1) - (9):

[0006] (1) In the preparation process, the mass ratio of the hydroxylated propylene-based copolymer resin to the sum of the three components including the polyisocyanate, the polyol oligomer, and the chain extender is (40 - 100) : (20 - 70);

[0007] (2) The molar ratio of the hydroxyl group content in the hydroxylated allyl copolymer resin in the preparation process to the isocyanate group in the polyisocyanate is (0.1 - 2) : (0.5 - 3);

[0008] (3) The mass ratio of the polyisocyanate, polyol oligomer, and chain extender in the preparation process is (0.5 - 5) : (0.2 - 4) : (0.2 - 4);

[0009] (4) The hydroxylated allyl copolymer resin in the preparation process is selected from one or more of ZKKY PP200, GI - 2000, Krasol LBH - 2000, SCR STANDARD SCPP - 80517, and BASF P188;

[0010] (5) The polyisocyanate in the preparation process is selected from one or more of 4,4'-methylenebis(phenyl isocyanate), 4,4 - diisocyanatodicyclohexylmethane, isophorone diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate;

[0011] (6) The polyol oligomer in the preparation process is selected from one or more of polycaprolactone diol, polytetrahydrofuran, polycarbonate diol, and polypropylene oxide diol;

[0012] (7) The chain extender in the preparation process is selected from one or more of 1,4 - butanediol, ethylenediamine, ethylene glycol, and hydroquinone bis(β - hydroxyethyl) ether;

[0013] (8) The number - average molecular weight of the allyl copolymer resin matrix is 80,000 - 100,000;

[0014] (9) The melt flow rate of the allyl copolymer resin matrix is 0.1 - 3 g / 10 min.

[0015] In some embodiments, the general structural formula of the allyl copolymer resin matrix is:

[0016]

[0017] In the formula: the x - segment is a structure derived from the hydroxylated allyl copolymer resin or the polyol oligomer, or a structure obtained by polymerization of the hydroxylated allyl copolymer resin and the polyol oligomer; the y - segment is a structure derived from the polymerization of the polyisocyanate and the chain extender; x is 3 - 40, and y is 100 - 240.

[0018] Second, the present invention also provides a preparation method of an allyl copolymer resin matrix, comprising the following steps:

[0019] Mix a polyol oligomer with a hydroxylated propenyl copolymer resin. Under a nitrogen atmosphere, add a polyisocyanate and a catalyst, and conduct a prepolymerization reaction to obtain a prepolymer material. Add a chain extender to the prepolymer material to conduct a chain extension reaction to obtain a propenyl copolymer resin matrix.

[0020] In a third aspect, the present invention also provides a semiconductive shielding material, which comprises a propenyl copolymer resin matrix, or includes a propenyl copolymer resin matrix prepared according to the preparation method of the propenyl copolymer resin matrix.

[0021] The semiconductive shielding material contains a conductive filler, and the mass ratio of the propenyl copolymer resin matrix to the conductive filler is (50-100):(15-50).

[0022] Optionally, the semiconductive shielding material may further contain an additive, and the mass ratio of the propenyl copolymer resin matrix to the additive in the semiconductive shielding material is 100:(0.01-5);

[0023] The additive includes at least one of the following (1) to (4):

[0024] (1) The additive is an antioxidant selected from one or more of antioxidant 1010, antioxidant 1035, and antioxidant 300;

[0025] (2) The additive is an anti-copper agent selected from one or more of anti-copper agent 1024, Irgafos 168, Chimassorb 944, and Tinuvin770;

[0026] (3) The additive is a lubricant selected from one or more of silicone masterbatch, stearic acid, pentaerythritol stearate, polyethylene wax, and oxidized polyethylene wax;

[0027] (4) The mass ratio of the propenyl copolymer resin matrix to the additive in the semiconductive shielding material is 100:(0.01-5).

[0028] In a fourth aspect, the present invention also provides a shielding layer comprising the semiconductive shielding material.

[0029] In a fifth aspect, the present invention also provides a cable, which includes a conductor, and the shielding layer, an insulating layer, and a protective sheath sequentially coated on the surface of the conductor.

[0030] Optionally, the insulating layer is a polypropylene insulating layer;

[0031] Optionally, the cable is a high-voltage DC cable with a voltage reaching 220 kV or above.

[0032] Compared with the prior art, the beneficial effects of the present invention include:

[0033] The present invention provides an allyl copolymer resin matrix with a specific molecular structure prepared from a hydroxylated allyl copolymer resin, a polyisocyanate, a polyol oligomer, and a chain extender. Flexible segments and polar segments are introduced into the molecular structure, reducing the hardness of the non-polar polypropylene material, enhancing the toughness and elasticity of the polypropylene material, and reducing the use of elastomers. Secondly, due to the introduction of flexible segments and polar segments in the allyl copolymer resin matrix of the present invention, the molecular chains have a certain relative slipperiness, and the structure has a certain dynamic adjustable performance. Therefore, it has excellent dispersion performance and can uniformly disperse conductive filler particles in the semi-conductive shielding material of the cable, reducing the problem of selective dispersion of conductive filler particles and the phase separation phenomenon caused by the accumulation of conductive filler particles. At the same time, it can also optimize the proportion of the conductive channels and percolation structures formed by the conductive filler particles, improving the performance of the semi-conductive shielding material. In addition, the allyl copolymer resin matrix of the present invention has a high melt viscosity, thereby improving its processing performance and the anti-eccentric ability after the cable is extruded, and the surface of the extruded product is smooth. It has good compatibility with the polypropylene insulating material, can better cooperate with the polypropylene insulating layer, and reduce the problem of injection and accumulation of space charges. The allyl copolymer resin matrix material of the present invention can be recycled, meeting the requirements of environmentally friendly cables. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments and descriptions thereof of this application are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0035] Figure 1 It is the GPC curve (molecular weight distribution test result) of the vinyl copolymer resin matrix A1 prepared in the first part provided by the present invention.

[0036] Figure 2 It is the SEM image of the semi-conductive shielding material prepared in Example 1 provided by the present invention.

[0037] Figure 3 It is the SEM image of the semi-conductive shielding material prepared in Example 2 provided by the present invention.

[0038] Figure 4 It is the SEM image of the semi-conductive shielding material of Comparative Example 1 provided by the present invention.

[0039] Figure 5 It is the SEM image of the semi-conductive shielding material prepared in Comparative Example 2 provided by the present invention.

[0040] Figure 6 It is the stress-strain curve graph of the semi-conductive shielding materials prepared in Examples 1-5 and Comparative Examples 1-2 provided by the present invention. Detailed implementation manners

[0041] To facilitate the understanding of the present invention, the following provides a more comprehensive description of the technical solution of the present invention with reference to the preferred embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0042] It should be noted that the experimental methods without specific conditions in the following embodiments of the present invention are generally carried out under conventional conditions or according to the conditions recommended by the manufacturers. All kinds of commonly used chemical reagents used in the embodiments are commercially available products.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used 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.

[0044] To better understand the technical solution in the invention, the following explanations and descriptions are made for related terms:

[0045] Copolymerization: It refers to the reaction of polymerizing two or more compounds under certain conditions into one substance. According to the number of types of monomers, it can be divided into binary and ternary copolymerizations. According to the different molecular structures of the polymers, it can be divided into random copolymerization, block copolymerization, alternating copolymerization, and graft copolymerization.

[0046] Polar chain segment: It can also be called a rigid chain segment, with a relatively fixed structure and no ability to expand or contract.

[0047] Flexible chain segment: It has a large ability to expand and contract.

[0048] In a first aspect, the present invention provides a propylene-based copolymer resin matrix, which is prepared from a hydroxylated propylene-based copolymer resin, a polyisocyanate, a polyol oligomer, and a chain extender, and the hydroxyl content in the hydroxylated propylene-based copolymer resin is 0.2 mol% - 3 mol%.

[0049] The structure of the propylene-based copolymer resin matrix prepared by the present invention includes polar segments and flexible segments, and is prepared from a hydroxylated propylene-based copolymer resin, a polyisocyanate, a polyol oligomer, and a chain extender. Among them, the polar segments are structures obtained by polymerizing the hydroxylated propylene-based copolymer resin and / or the polyol oligomer, and the flexible segments are structures obtained by polymerizing the polyisocyanate and the chain extender. The polar segments and the flexible segments are connected by a copolymerization method. Among them, the polar segments containing the hydroxylated propylene-based copolymer resin and / or the polyol oligomer can regulate the order of molecules in the matrix structure, provide structural stability, and improve the hardness and strength of the matrix; the flexible segments containing the polyisocyanate and the chain extender have a certain deformation ability, can regulate the plasticity and toughness of the matrix, avoid reducing the material hardness in the way of physically blending elastomers, and can regulate the processing and molding performance of the matrix.

[0050] In some embodiments, the mass ratio of the hydroxylated propylene-based copolymer resin to the three components including the polyisocyanate, the polyol oligomer, and the chain extender in the preparation process is (40-100):(20-70); including but not limited to mass ratios of 40:20, 40:30, 40:40, 40:50, 40:60, 40:70, 50:20, 50:30, 50:40, 50:50, 50:60, 50:70, 60:20, 60:30, 60:40, 60:50, 60:60, 60:70, 70:20, 70:30, 70:40, 70:50, 70:60, 70:70, 80:20, 80:30, 80:40, 80:50, 80:60, 80:70, 90:20, 90:30, 90:40, 90:50, 90:60, 90:70, 100:20, 100:30, 100:40, 100:50, 100:60, 100:70, or any ratio within the range formed by any two of the foregoing and any ratio within that range.

[0051] In some embodiments, the molar ratio of the hydroxyl group content in the hydroxylated propylene-based copolymer resin to the isocyanate group in the polyisocyanate in the preparation process is (0.1-2):(0.5-3), including but not limited to molar ratios of 0.1:0.5, 0.1:1, 0.1:1.5, 0.1:2, 0.1:2.5, 0.1:3, 0.5:0.5, 0.5:1, 0.5:1.2, 0.5:2, 0.5:1.5, 0.5:3, 1:0.5, 1:0.8, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1.5:0.5, 1.5:1, 1.5:2, 1.5:2.5, 1.5:3, 2:0.5, 2:0.8, 2:1, 2:1.5, 2:2, 2:2.5, 2:3, or any ratio within the range formed by any two of the foregoing and any ratio within that range.

[0052] In some embodiments, the mass ratio of polyisocyanate, polyol oligomer, and chain extender in the preparation process is (0.5 - 5):(0.2 - 4):(0.2 - 4), including but not limited to mass ratios of 0.5:0.2:0.2, 0.5:0.2:0.5, 0.5:0.2:1, 0.5:0.2:2, 0.5:0.2:3, 0.5:0.2:4, 1:0.2:0.2, 1:2:4, 1:4:0.2, 1:4:4, 2:0.2:0.2, 5:0.2:0.2, 2:4:4, 2:4:0.2, 2:0.2:4, 5:0.2:0.2, 5:0.2:4, 5:4:0.2, or any range formed by any two of the foregoing and any ratio within the range.

[0053] Furthermore, an excessive addition amount of polyisocyanate among the three components of polyisocyanate, polyol oligomer, and chain extender can better achieve the technical effects of the present invention. For example, the mass ratio of polyisocyanate, polyol oligomer, and chain extender is (1 - 5):(0.2 - 0.5):(0.2 - 0.5), including but not limited to ranges such as (2 - 5):(0.2 - 1):(0.2 - 1) or (3 - 5):(0.2 - 1.5):(0.2 - 1.5) or (4 - 5):(0.2 - 2):(0.2 - 2), etc.

[0054] In some embodiments, the hydroxylated propylene-based copolymer resin in the preparation process of the propylene-based copolymer resin matrix is 40 - 100 parts by mass, the polyisocyanate is 10 - 60 parts by mass, the polyol oligomer is 5 - 40 parts by mass, and the chain extender is 5 - 40 parts by mass.

[0055] In some embodiments, the hydroxylated propylene-based copolymer resin in the preparation process of the propylene-based copolymer resin matrix is 50 - 75 parts by mass, the polyisocyanate is 20 - 30 parts by mass, the polyol oligomer is 10 - 20 parts by mass, and the chain extender is 10 - 20 parts by mass.

[0056] In some embodiments, the contents of the copolymerized polar segment and flexible segment will affect the mechanical properties, dispersion properties, and processing properties, etc. of the propylene-based copolymer resin matrix. Therefore, the propylene-based copolymer resin matrix provided by the present invention can further control the degree of polymerization and molecular weight of the polar segment and flexible segment by further defining the mass fractions and ratios of the hydroxylated propylene-based copolymer resin, polyisocyanate, polyol oligomer, and chain extender in the raw materials, and can enable the propylene-based copolymer resin matrix to obtain better performance.

[0057] In some embodiments, the hydroxylated propenyl copolymer resin in the preparation process is selected from one or more of ZKKY PP200, GI-2000, Krasol LBH-2000, SCRSTANDARD SCPP-80517, and BASF P188.

[0058] In some embodiments, the polyisocyanate in the preparation process is selected from one or more of 4,4'-methylenebis(phenyl isocyanate), 4,4-diisocyanatodicyclohexylmethane, isophorone diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate; further, the matrix properties of the propenyl copolymer resin prepared from 4,4'-methylenebis(phenyl isocyanate) and 4,4-diisocyanatodicyclohexylmethane are better.

[0059] In some embodiments, the polyol oligomer in the preparation process is selected from one or more of polycaprolactone diol, polytetrahydrofuran, polycarbonate diol, and polypropylene oxide diol; further, the matrix properties of the propenyl copolymer resin prepared from polycaprolactone diol and polytetrahydrofuran are better.

[0060] In some embodiments, the chain extender in the preparation process is selected from one or more of 1,4-butanediol, ethylenediamine, ethylene glycol, and hydroquinone bis(β-hydroxyethyl) ether; further, the matrix properties of the propenyl copolymer resin obtained by the chain extension reaction with 1,4-butanediol are better.

[0061] In some embodiments, the number-average molecular weight of the propenyl copolymer resin matrix is 80,000 to 100,000; further, when the number-average molecular weight of the propenyl copolymer resin matrix is 90,000 to 100,000, better performance can be achieved.

[0062] In some embodiments, the melt flow rate of the propenyl copolymer resin matrix is 0.1 - 3 g / 10 min.

[0063] In some embodiments, the general structural formula of the propenyl copolymer resin matrix is:

[0064]

[0065] In the formula: the x segment is a structure derived from the hydroxylated propenyl copolymer resin or the polyol oligomer, or a structure obtained by polymerization of the hydroxylated propenyl copolymer resin and the polyol oligomer; the y segment is a structure derived from the polymerization of the polyisocyanate and the chain extender; x is 3 to 40, and y is 100 to 240.

[0066] With the above-mentioned raw materials, functional segments of flexible segments and polar segments are introduced in the polymerization stage, and further, the content of the functional segments is adjusted by regulating the types and addition amounts of polyisocyanate, polyol oligomer and chain extender, so as to better control the mechanical properties, dispersion properties, processing properties, etc. of the propylene-based copolymer resin matrix.

[0067] In a second aspect, the present invention also provides a preparation method of a propylene-based copolymer resin matrix, comprising the following steps:

[0068] Mix the polyol oligomer with the hydroxylated propylene-based copolymer resin, and under a nitrogen atmosphere, add polyisocyanate and a catalyst to carry out a prepolymerization reaction to obtain a prepolymerized material, and add a chain extender to the prepolymerized material to carry out a chain extension reaction to obtain a propylene-based copolymer resin matrix.

[0069] In some embodiments, the hydroxylated propylene-based copolymer resin in the preparation process is selected from one or more of ZKKYPP200, GI-2000 and Krasol LBH-2000.

[0070] In some embodiments, the polyisocyanate in the preparation process is selected from one or more of 4,4'-methylenebis(phenyl isocyanate), 4,4-diisocyanatodicyclohexylmethane, isophorone diisocyanate, hexamethylene diisocyanate and toluene diisocyanate; further, the propylene-based copolymer resin matrix prepared from 4,4'-methylenebis(phenyl isocyanate) and 4,4-diisocyanatodicyclohexylmethane has better performance.

[0071] In some embodiments, the polyol oligomer in the preparation process is selected from one or more of polycaprolactone diol, polytetrahydrofuran, polycarbonate diol and polypropylene oxide diol; further, the propylene-based copolymer resin matrix prepared from polycaprolactone diol and polytetrahydrofuran has better performance.

[0072] In some embodiments, the chain extender in the preparation process is selected from one or more of 1,4-butanediol, ethylenediamine, ethylene glycol and hydroquinone bis(β-hydroxyethyl) ether; further, the propylene-based copolymer resin matrix obtained by the chain extension reaction with 1,4-butanediol has better performance.

[0073] In some embodiments, the catalyst is selected from organometallic catalysts;

[0074] Optionally, the organometallic catalyst can be dibutyltin dilaurate.

[0075] In some embodiments, in the propylene-based copolymer resin matrix, the hydroxylated propylene-based copolymer resin is 40-100 parts by mass, and the sum of the three components of polyisocyanate, polyol oligomer and chain extender is 20-70 parts by mass.

[0076] Optionally, the hydroxylated allyl copolymer resin includes, but is not limited to, 40, 42, 45, 48, 50, 52, 55, 58, 60, 62, 65, 68, 70, 72, 75, 78, 80, 82, 85, 88, 90, 92, 95, 98, 100 parts by mass, or a range formed by any two of the foregoing and any value within the range.

[0077] Optionally, the total amount of the polyisocyanate, polyol oligomer, and chain extender includes, but is not limited to, 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, 45, 48, 50, 52, 55, 58, 60, 62, 65, 68, 70 parts by mass, or a range formed by any two of the foregoing and any value within the range.

[0078] In some embodiments, the mass ratio of the polyisocyanate, polyol oligomer, and chain extender is (0.5 - 5):(0.2 - 4):(0.2 - 4), including, but not limited to, mass ratios of 0.5:0.2:0.2, 0.5:0.2:0.5, 0.5:0.2:1, 0.5:0.2:2, 0.5:0.2:3, 0.5:0.2:4, 1:0.2:0.2, 1:2:4, 1:4:0.2, 1:4:4, 2:0.2:0.2, 5:0.2:0.2, 2:4:4, 2:4:0.2, 2:0.2:4, 5:0.2:0.2, 5:0.2:4, 5:4:0.2, or a range formed by any two of the foregoing and any ratio within the range.

[0079] In some embodiments, before mixing the polyol oligomer in the preparation method, it can be first melted and dried; optionally, the melting can be carried out in a vacuum oven, the drying temperature of the polyol oligomer can be selected from 80 to 100 °C, and the drying time can be selected from 8 to 24 h.

[0080] In some embodiments, before mixing the hydroxylated allyl copolymer resin in the preparation method, it can be dried; optionally, the drying temperature of the hydroxylated allyl copolymer resin can be selected from 80 to 100 °C, and the drying time can be selected from 8 to 24 h.

[0081] In some embodiments, before adding the chain extender in the preparation method, it can be first heated and melted.

[0082] In some embodiments, the temperature of the prepolymerization reaction can be 100 to 200 °C.

[0083] In some embodiments, before adding the polyisocyanate and the catalyst, the nitrogen atmosphere can be heated to 100 to 200 °C.

[0084] In some embodiments, after the chain extension reaction is completed, the chain-extended product can be poured into a mold and then dried;

[0085] Optionally, the drying can be carried out in a box such as an oven, a vacuum box, a forced-air oven, etc.

[0086] Optionally, the drying temperature can be 80 - 120 °C, and the drying time can be 0.5 - 12 h;

[0087] Optionally, the mold is preheated first;

[0088] Optionally, the drying can be carried out by programmed drying, including but not limited to two-stage, three-stage, four-stage, etc. programmed drying;

[0089] In some embodiments, the drying selects two-stage programmed drying, specifically as follows:

[0090] (1) The first-stage drying program: at 100 - 120 °C, the drying time can be 0.5 - 2 h;

[0091] (2) The second-stage drying program: at 80 - 100 °C, the drying time can be 8 - 12 h.

[0092] The main purpose of the preparation method provided by the present invention is to obtain a propylene-based copolymer resin matrix having a copolymerized polar segment and a flexible segment structure, and to better implement this technical solution by controlling the moisture and mixing addition amount of raw materials, the temperature and time of the prepolymerization reaction, and the temperature and time of the chain extension reaction, the drying process of the chain-extended product, etc.

[0093] In the third aspect, the present invention also provides a semiconductive shielding material, which comprises a propylene-based copolymer resin matrix, or includes a propylene-based copolymer resin matrix prepared by the above-mentioned preparation method of the propylene-based copolymer resin matrix.

[0094] Another object of the propylene-based copolymer resin matrix provided by the present invention is to have excellent compatibility and dispersion ability, and can have good compatibility with other components in the semiconductive shielding material, and no phase separation and other phenomena will occur.

[0095] In some embodiments, the semiconductive shielding material contains conductive fillers, and the mass ratio of the propylene-based copolymer resin matrix to the conductive fillers is (50 - 100):(15 - 50); including but not limited to 50:15, 50:20, 50:30, 50:40, 50:50, 60:15, 60:20, 60:30, 60:40, 60:50, 70:15, 70:20, 70:30, 70:40, 70:50, 80:15, 80:20, 80:30, 80:40, 80:50, 90:15, 90:20, 90:30, 90:40, 90:50, 100:15, 100:20, 100:30, 100:40, 100:50 or any ratio within the range formed by any two of the foregoing and any ratio within that range.

[0096] Since polypropylene is a non-polar material, conductive fillers cannot be evenly dispersed in polypropylene. Another object of the propylene-based copolymer resin matrix provided by the present invention is to have excellent compatibility and dispersibility, especially super-dispersibility for substances such as conductive filler particles, and will not cause phenomena such as agglomeration of conductive filler particles. Therefore, the problem of the dispersibility of conductive filler particles in the semiconductive shielding material is solved.

[0097] Secondly, since the propylene-based copolymer resin matrix provided by the present invention itself has special copolymer polar segments and flexible segments, and has a specific molecular size and polymer, it has very excellent mechanical properties. Therefore, there is no need to add polar substances such as elastomers / elastic resins to regulate the mechanical properties of the matrix, thus avoiding the phenomenon that conductive filler particles are dispersed in the elastomer phase and a large amount of accumulation occurs, which exacerbates the unevenness of the distribution of conductive filler particles and makes the electrical and mechanical properties of the semiconductive shielding material unable to meet the use requirements.

[0098] In addition, due to the special molecular structure of the propylene-based copolymer resin matrix provided by the present invention, the proportion of the conductive channels and percolation structures formed by the conductive filler particles is synergistically optimized, and the conductive performance is excellent. At the same time, there are more branched structures, which increase the melt viscosity of the system, thereby improving the processing performance, thermo-mechanical performance and the anti-eccentric ability after the cable is extruded, and the surface of the extruded product is smooth.

[0099] In some embodiments, the semiconductive shielding material further contains one or more additives such as antioxidants, anti-copper agents and lubricants;

[0100] Optionally, the antioxidant is selected from one or more of antioxidant 1010, antioxidant 1035 and antioxidant 300;

[0101] Optionally, the anti-copper agent is selected from one or more of anti-copper agent 1024, Irgafos 168, Chimassorb 944 and Tinuvin770;

[0102] Optionally, the lubricant is selected from one or more of silicone masterbatch, stearic acid, pentaerythritol stearate, polyethylene wax, and oxidized polyethylene wax;

[0103] In some embodiments, the mass ratio of the propylene-based copolymer resin matrix to the additives in the semiconductive shielding material is 100:(0.01 - 5); including but not limited to 100:0.01, 100:0.05, 100:0.08, 100:0.1, 100:0.2, 100:0.3, 100:0.4, 100:0.5, 100:0.08, 100:1, 100:1.2, 100:1.5, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5, 100:5, or any range formed by any two of the foregoing and any ratio within the range.

[0104] Fourthly, the present invention also provides a shielding layer comprising a semiconductive shielding material.

[0105] Fifthly, the present invention also provides a cable, which includes a conductor, and the shielding layer, insulating layer, and protective sheath sequentially coated on the surface of the conductor.

[0106] Optionally, the insulating layer is a polypropylene insulating layer.

[0107] Optionally, the cable is a polypropylene (PP) insulated cable. The polypropylene insulating material has excellent insulation performance, does not require cross-linking, has a high working temperature, can be melted and reused, etc. Moreover, there are no cross-linking and degassing processes in the production process, which significantly reduces carbon emissions and has an energy-saving advantage. The polypropylene insulating material can be recycled after the cable is retired, which has an environmental protection advantage. The polypropylene insulation has no pores, no gels, and no small molecule chemical impurities, and has high cleanliness and natural water tree resistance. The propylene-based copolymer resin matrix provided by the present invention plays a role of a heat-resistant skeleton in the semiconductive shielding material, has a melting temperature similar to that of the polypropylene material, and can maintain the stability of the insulation structure when the cable exceeds the rated working conditions. At the same time, the semiconductive shielding material containing the propylene-based copolymer resin matrix has high compatibility with the polypropylene insulating material, can better cooperate with the polypropylene insulating layer, reduce the injection and accumulation problems of space charges, effectively reduce the macroscopic resistivity of the semiconductive shielding material, and at the same time has good heat resistance, mechanical properties, and electrical properties. It is expected to break through the bottleneck in the development of ultra-high voltage cable insulation technology when used in polypropylene insulated cables, and is an important direction for the development of power cable technology.

[0108] Optionally, the cable is a high-voltage direct current cable with a voltage reaching 220 kV or above.

[0109] For experimental parameters not specified in the following specific embodiments, reference is made to the instructions given in the present application document, and reference may also be made to experimental manuals in the art or other experimental methods known in the art, or to experimental conditions recommended by manufacturers.

[0110] The raw materials and reagents involved in the following specific examples can be obtained from commercial sources, or can be prepared by those skilled in the art according to known methods.

[0111] The sources of some of the substances involved in the present invention are as follows:

[0112] The hydroxylated propylene copolymer resin is selected from one or more of ZKKY PP200 from Zhongke Keyou, GI-2000 from Japan Soda, Krasol LBH-2000 from Krasol, SCRSTANDARD SCPP-80517 and BASF P188.

[0113] The conductive carbon black is XC72R produced by CABOT, with a particle size of 30nm and a specific surface area of 254m 2 / g.

[0114] In this embodiment, the antioxidant is selected from antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), antioxidant 1035 (2,2'-thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), antioxidant 300 (4,4'-thiobis(6-tert-butyl-3-methylphenol)), and the anti-copper agent is anti-copper agent 1024 (1,2-bis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine). The antioxidant and the anti-copper agent are purchased from BASF; the lubricant is silicone masterbatch.

[0115] Part I: Preparation of Propylene Copolymer Resin Matrix

[0116] (1) Propylene copolymer resin matrix A1 sample

[0117] The method for preparing the propylene copolymer resin matrix (A1) is carried out according to the following steps:

[0118] S1. Melting polycaprolactone diol in a vacuum oven, and vacuum drying at 80° C. for 12 h to obtain molten polycaprolactone diol, and vacuum drying hydroxylated propylene copolymer resin Krasol LBH-2000 at 80° C. for 24 h;

[0119] S2, placing the molten polycaprolactone diol and the dried hydroxylated propylene copolymer resin Krasol LBH-2000 in a glass reactor, mixing and stirring, heating to 100° C. under a nitrogen atmosphere, and then adding 4,4'-methylenebis(phenyl isocyanate) and dibutyltin dilaurate to carry out a prepolymerization reaction to obtain a prepolymer material;

[0120] S3. Heat 1,4 - butanediol to melt it, add it to the prepolymer material, and continue stirring for chain - extension reaction to obtain a chain - extended product. Pour the chain - extended product into a pre - heated mold, place it in a drying oven, heat it at 110 °C for 1 h, and then heat it at 90 °C for 8 h to obtain an allyl copolymer resin matrix, denoted as A1.

[0121] In this example, the molar ratio of 4,4'-methylenebis(phenyl isocyanate), polycaprolactone diol, and 1,4 - butanediol is 2:1:1. The molar ratio of the hydroxyl groups in the hydroxylated allyl copolymer resin Krasol LBH - 2000 to the isocyanate groups in 4,4'-methylenebis(phenyl isocyanate) is 1:1, and the addition amount of dibutyltin dilaurate is 5 ppm of the total mass of the materials.

[0122] The melt flow rate of the allyl copolymer resin matrix A1 is 1.12 g / 10 min.

[0123] (2) Sample of allyl copolymer resin matrix A2

[0124] The preparation method of the allyl copolymer resin matrix (A2) is carried out according to the following steps:

[0125] The preparation method in this example is carried out according to the following steps:

[0126] S1. Place polycaprolactone diol in a vacuum oven to melt it, and then vacuum - dry it at 80 °C for 12 h to obtain molten polycaprolactone diol. Vacuum - dry the hydroxylated allyl copolymer resin Krasol LBH - 2000 at 80 °C for 24 h.

[0127] S2. Mix and stir the molten polycaprolactone diol and the dried hydroxylated allyl copolymer resin Krasol LBH - 2000 in a glass reaction kettle, heat it to 100 °C under a nitrogen atmosphere, and then add 4,4'-methylenebis(phenyl isocyanate) and dibutyltin dilaurate for prepolymerization reaction to obtain a prepolymer material.

[0128] S3. Heat 1,4 - butanediol to melt it, add it to the prepolymer material, and continue stirring for chain - extension reaction to obtain a chain - extended product. Pour the chain - extended product into a pre - heated mold, place it in a drying oven, heat it at 110 °C for 1 h, and then heat it at 90 °C for 8 h to obtain an allyl copolymer resin matrix, denoted as A2.

[0129] In this embodiment, the molar ratio of 4,4'-methylenebis(phenyl isocyanate), polycaprolactone diol, and 1,4-butanediol is 2:1:1. The molar ratio of the hydroxyl groups in the hydroxylated allyl copolymer resin Krasol LBH-2000 to the isocyanate groups in 4,4'-methylenebis(phenyl isocyanate) is 2:0.5, and the content of dibutyltin dilaurate is 5 ppm.

[0130] The melt flow rate of the allyl copolymer resin matrix A2 is 1.35 g / 10 min.

[0131] (3) Allyl copolymer resin matrix A3 sample

[0132] The preparation method of the allyl copolymer resin matrix (A3) is carried out according to the following steps:

[0133] S1. Place polytetrahydrofuran in a vacuum oven to melt it, and then vacuum dry it at 80 °C for 12 h to obtain molten polytetrahydrofuran. Vacuum dry the hydroxylated allyl copolymer resin Krasol LBH-2000 at 80 °C for 24 h.

[0134] S2. Place the molten polytetrahydrofuran and the dried hydroxylated allyl copolymer resin Krasol LBH-2000 in a glass reaction kettle, mix and stir them, heat them to 100 °C under a nitrogen atmosphere, and then add 4,4'-methylenebis(phenyl isocyanate) and dibutyltin dilaurate for a prepolymerization reaction to obtain a prepolymerized material.

[0135] S3. Heat 1,4-butanediol to melt it, add it to the prepolymerized material and continue stirring for a chain extension reaction to obtain a chain-extended product. Pour the chain-extended product into a preheated mold, place it in a drying oven and heat it at 110 °C for 1 h, and then heat it at 90 °C for 8 h to obtain the allyl copolymer resin matrix, denoted as A3.

[0136] In this embodiment, the molar ratio of 4,4'-methylenebis(phenyl isocyanate), polytetrahydrofuran, and 1,4-butanediol is 2:1:1. The molar ratio of the hydroxyl groups in the hydroxylated allyl copolymer resin Krasol LBH-2000 to the isocyanate groups in 4,4'-methylenebis(phenyl isocyanate) is 1:1, and the content of dibutyltin dilaurate is 5 ppm.

[0137] The melt flow rate of the allyl copolymer resin matrix A3 is 1.12 g / 10 min.

[0138] (4) Allyl copolymer resin matrix A4 sample

[0139] The preparation method of the allyl copolymer resin matrix (A4) is carried out according to the following steps:

[0140] S1. After melting polycaprolactone diol in a vacuum oven, vacuum dry it at 80 °C for 12 h to obtain molten polycaprolactone diol, and vacuum dry hydroxylated propylene-based copolymer resin GI-2000 at 80 °C for 24 h;

[0141] S2. Place the molten polycaprolactone diol and the dried hydroxylated propylene-based copolymer resin GI-2000 in a glass reaction kettle, mix and stir them, heat up to 100 °C under a nitrogen atmosphere, and then add 4,4'-dicyclohexylmethane diisocyanate and dibutyltin dilaurate for prepolymerization reaction to obtain a prepolymerized material;

[0142] S3. Heat 1,4-butanediol to melt it, add it to the prepolymerized material and continue stirring for chain extension reaction to obtain a chain-extended product. Pour the chain-extended product into a preheated mold, place it in a drying oven and heat it at 110 °C for 1 h, and then heat it at 90 °C for 8 h to obtain a propylene-based copolymer resin matrix, denoted as A4.

[0143] In this example, the molar ratio of 4,4'-dicyclohexylmethane diisocyanate, polycaprolactone diol, and 1,4-butanediol is 2:1:1. The molar ratio of the hydroxyl group in the hydroxylated propylene-based copolymer resin GI-2000 to the isocyanate group in 4,4'-dicyclohexylmethane diisocyanate is 1:1, and the content of dibutyltin dilaurate is 5 ppm.

[0144] The melt flow rate of the propylene-based copolymer resin matrix A4 is 1.08 g / 10 min.

[0145] (5) Propylene-based copolymer resin matrix A5 sample

[0146] The preparation method of the propylene-based copolymer resin matrix (A4) is carried out according to the following steps:

[0147] S1. After melting polycaprolactone diol in a vacuum oven, vacuum dry it at 80 °C for 12 h to obtain molten polycaprolactone diol, and vacuum dry hydroxylated propylene-based copolymer resin Krasol LBH-2000 at 80 °C for 24 h;

[0148] S2. Place the molten polycaprolactone diol and the dried hydroxylated propylene-based copolymer resin Krasol LBH-2000 in a glass reaction kettle, mix and stir them, heat up to 100 °C under a nitrogen atmosphere, and then add 4,4'-dicyclohexylmethane diisocyanate and dibutyltin dilaurate for prepolymerization reaction to obtain a prepolymerized material;

[0149] S3. Heat 1,4-butanediol until it melts, add it to the prepolymer material, and continue stirring for chain extension reaction to obtain a chain-extended product. Pour the chain-extended product into a preheated mold, place it in a drying oven, heat it at 110 °C for 1 h, and then heat it at 90 °C for 8 h to obtain an allyl copolymer resin matrix, denoted as A4.

[0150] In this example, the molar ratio of 4,4-diisocyanatodicyclohexylmethane, polycaprolactone diol, and 1,4-butanediol is 0.5:1:1. The molar ratio of the hydroxyl groups in the hydroxylated allyl copolymer resin Krasol LBH-2000 to the isocyanate groups in 4,4-diisocyanatodicyclohexylmethane is 1:1, and the content of dibutyltin dilaurate is 5 ppm.

[0151] The melt flow rate of the allyl copolymer resin matrix A5 is 2.51 g / 10 min.

[0152] During the preparation process of this part, the total mass of the charged materials is the same. The number-average molecular weight of the prepared allyl copolymer resin matrices A1 - A5 is 80,000 - 100,000. Among them, the number-average molecular weight M n = 90148, as shown by the GPC curve (molecular weight distribution test result) in the appendix Figure 1 shown.

[0153] Second part: Preparation of semi-conductive shielding material

[0154] Example 1

[0155] The preparation method in this example is carried out according to the following steps:

[0156] By mass fraction, place 100 parts of the allyl copolymer resin matrix (A1) in a mixer, and add 0.3 part of antioxidant 1010, 0.5 part of copper inhibitor 1024, 30 parts of conductive carbon black (XC72R), and 1 part of silicone masterbatch step by step. Melt and blend them at 180 °C for 10 min, and the mixer speed is 30 rpm to obtain a semi-conductive shielding material.

[0157] Example 2

[0158] The preparation method in this example is carried out according to the following steps:

[0159] By mass fraction, place 100 parts of the allyl copolymer resin matrix (A2) in a mixer, and add 0.3 part of antioxidant 1010, 0.5 part of copper inhibitor 1024, 30 parts of conductive carbon black (XC72R), and 1 part of silicone masterbatch step by step. Melt and blend them at 180 °C for 10 min, and the mixer speed is 30 rpm to obtain a semi-conductive shielding material.

[0160] Example 3

[0161] The preparation method in this embodiment is carried out according to the following steps:

[0162] By mass fraction, 100 parts of an allyl copolymer resin matrix (A1) are placed in a mixer, and 0.3 part of antioxidant 1010, 0.5 part of copper inhibitor 1024, 15 parts of conductive carbon black (XC72R), and 1 part of silicone masterbatch are added step by step. They are melt-blended at 180 °C for 10 min, and the mixer rotates at 30 rpm to obtain a semi-conductive shielding material.

[0163] Example 4

[0164] The preparation method in this embodiment is carried out according to the following steps:

[0165] By mass fraction, 100 parts of an allyl copolymer resin matrix (A3) are placed in a mixer, and 0.3 part of antioxidant 1010, 0.5 part of copper inhibitor 1024, 25 parts of conductive carbon black (XC72R), and 1 part of silicone masterbatch are added step by step. They are melt-blended at 180 °C for 10 min, and the mixer rotates at 30 rpm to obtain a semi-conductive shielding material.

[0166] Example 5

[0167] The preparation method in this embodiment is carried out according to the following steps:

[0168] By mass fraction, 100 parts of an allyl copolymer resin matrix (A4) are placed in a mixer, and 0.3 part of antioxidant 1010, 0.5 part of copper inhibitor 1024, 25 parts of conductive carbon black (XC72R), and 1 part of silicone masterbatch are added step by step. They are melt-blended at 180 °C for 10 min, and the mixer rotates at 30 rpm to obtain a semi-conductive shielding material.

[0169] Example 6

[0170] The preparation method in this embodiment is carried out according to the following steps:

[0171] By mass fraction, 100 parts of an allyl copolymer resin matrix (A5) are placed in a mixer, and 0.3 part of antioxidant 1010, 0.5 part of copper inhibitor 1024, 25 parts of conductive carbon black (XC72R), and 1 part of silicone masterbatch are added step by step. They are melt-blended at 180 °C for 10 min, and the mixer rotates at 30 rpm to obtain a semi-conductive shielding material.

[0172] Comparative Example 1

[0173] Semi-conductive shielding material for cross-linked polyethylene insulation purchased on the market.

[0174] Comparative Example 2

[0175] The semiconductive shielding material of this comparative example is basically the same as that of Example 1, except that the resin matrix in the semiconductive shielding material of this comparative example only has a different composition. The resin matrix of this comparative example is prepared by a method similar to that of the propylene-based copolymer resin matrix (A1), except that no hydroxylated propylene-based copolymer resin is fed during the preparation process, and the rest of the preparation method is the same as that of A1.

[0176] The remaining composition, addition ratio and preparation steps of the semiconductive shielding material of this comparative example are the same as those of Example 1.

[0177] Comparative Example 3

[0178] The semiconductive shielding material of this comparative example is basically the same as that of Example 1, except that the propylene-based copolymer resin matrix (A1) is different. In this comparison, a block copolymer polypropylene resin (K8003, Sinopec Maoming) is used to replace the hydroxylated propylene-based copolymer resin Krasol LBH-2000 to prepare the resin matrix B1, which is used in Example 1 to replace an equal amount of the propylene-based copolymer resin matrix (A1).

[0179] The number-average molecular weight of the resin matrix B1 is 80,000 - 150,000, and the melt flow rate is 2.4 g / 10 min.

[0180] The remaining composition, addition ratio and preparation steps are the same as those of Example 1.

[0181] Part Three, Testing Part

[0182] Test Example 1, Characterization of the Microscopic Morphology Characteristics of the Semiconductive Shielding Material

[0183] The semiconductive shielding materials of Examples 1 - 2 and Comparative Example 2 are respectively hot-pressed in a flat vulcanizer at 190°C and 15 MPa for 15 min, and the semiconductive shielding material of Comparative Example 1 is hot-pressed and cross-linked in a flat vulcanizer at 175°C and 15 MPa for 30 min. After making strip specimens with a thickness of 1 mm, low-temperature brittle fracture treatment is carried out, and the cross-section is characterized by a scanning electron microscope (SEM) to characterize the microscopic morphology characteristics of the semiconductive shielding material. The cross-sectional morphology is as Figures 2 to 5 shown.

[0184] From Figure 2 and Figure 3It can be seen that the semi-conductive shielding materials of Example 1 and Example 2 show the same morphological characteristics under the same magnification, and the cross-section is relatively flat. The main difference between the semi-conductive shielding materials of Example 1 and Example 2 lies in the compositional differences of the propylene-based copolymer resin matrices A1 and A2. Although the content of hydroxylated propylene-based copolymer resin in the propylene-based copolymer resin matrix A2 is relatively high and the size of the hydroxylated copolymer phase is relatively large, it is still evenly distributed. The carbon black particles in Example 1 and Example 2 are evenly dispersed, and the combination between the carbon black and the resin matrix is tight without obvious void defects. The particle size is distributed below 0.2 μm, and no selective distribution phenomenon is observed.

[0185] It can be seen from Figure 4 and Figure 5 that in Comparative Example 1, the carbon black particles are not evenly dispersed, there is a cluster structure, the diameter of the agglomerates is in the range of 0.5 μm - 1.5 μm, and there are obvious voids between the carbon black agglomerates and the surrounding matrix of the resin. The resin matrix of Comparative Example 2 does not contain hydroxylated propylene-based copolymer resin. Although the carbon black particles are relatively evenly dispersed and there are no obvious voids between the carbon black particles and the surrounding matrix of the resin, there is a certain cluster structure, and the diameter of the agglomerates is in the range of 0.5 μm to 1 μm.

[0186] In summary, the semi-conductive shielding material prepared from the propylene-based copolymer resin matrix of the present invention has excellent structure and morphology.

[0187] Test Example II: Mechanical Property Test of Semi-Conductive Shielding Material

[0188] The semi-conductive shielding materials of Examples 1 - 2 and Comparative Examples 2 - 3 were respectively hot-pressed in a flat vulcanizer at 190 °C and 15 MPa for 15 min, and the semi-conductive shielding material of Comparative Example 1 was hot-pressed and cross-linked in a flat vulcanizer at 175 °C and 15 MPa for 30 min. After making strip specimens with a thickness of 1 mm, mechanical property tests were carried out on the dumbbell-shaped specimens of the semi-conductive shielding material according to the GB / T2951-2008 standard. The test results are as Figure 6 shown:

[0189] The content of hydroxylated propylene-based copolymer resin in the propylene-based copolymer resin matrix A1 in Example 1 is relatively lower than that in Example 2. The yield phenomenon is less obvious than that in Example 2, and it has a lower modulus. The moduli of Comparative Examples 1 - 3 are significantly increased compared with those of Examples 1 - 2. Among the five semi-conductive shielding materials of Examples 1 - 2 and Comparative Examples 1 - 3, the elongation at break of Example 1 is the highest. The hardness of the two semi-conductive shielding materials of Examples 1 - 2 is moderate and both meet the index requirements of tensile strength ≥ 12 MPa and elongation at break ≥ 180% in the standard.

[0190] Test Example III: Melt Flow Index of Semi-Conductive Shielding Material

[0191] The melt flow indices of the semiconductive shielding materials of Examples 1 to 6 and Comparative Examples 2 to 3 were measured at 230°C and 2.16 kg, and the melt flow rate of the semiconductive shielding material of Comparative Example 1 was measured at 120°C and 2.16 kg. The results are shown in Table 1:

[0192] Table 1: Melt Flow Rate of Semiconductive Shielding Material

[0193] Sample Melt flow rate (g / 10 min) Example 1 0.05 Example 2 0.055 Example 3 0.07 Example 4 0.045 Example 5 0.047 Example 6 0.085 Comparative Example 1 0.01 Comparative Example 2 0.2 Comparative Example 3 0.085

[0194] The melt flow indices of Examples 1 to 6 and Comparative Example 3 do not exceed 0.085 g / 10 min, having a relatively low melt flow rate, which may be related to the components and contents in the semiconductive shielding material, especially possibly related to the matrix component of the propylene-based copolymer resin, the carbon black content and dispersion in the semiconductive shielding material. However, the melt flow velocity of the semiconductive shielding material of Comparative Example 1 is significantly too low, and the melt flow velocity of the semiconductive shielding material of Comparative Example 2 is too high, making it difficult to control the industrial forming process, and the error of the prepared shielding layer is relatively large.

[0195] Test Example 4: Volume Resistivity of Semiconductive Shielding Material

[0196] Specimens of the semiconductive shielding materials of Examples 1 to 6 and Comparative Examples 1 to 3 were prepared according to the standard of GB / T 3048.3—2007, and the volume resistivity of the semiconductive shielding materials was tested at 20°C and 90°C respectively. The test results are shown in Table 2 and Table 3 respectively:

[0197] Table 2: Test Results of Volume Resistivity of Semiconductive Shielding Material at 20°C

[0198] Sample Volume resistivity rate (Ωcm) Example 1 21.2 Example 2 12.5 Example 3 79 Example 4 18.3 Example 5 19.2 Example 6 105 Comparative Example 1 15.2 Comparative Example 2 120 Comparative Example 3 98

[0199] It can be seen from the test results of the volume resistivity of the semiconductive shielding material at 20°C in Table 2 that in the semiconductive shielding materials prepared in Examples 1 to 6 of the present invention, the distribution of the matrix and carbon black particles is homogenized, the carbon black particles no longer agglomerate in large areas, and conduct electricity through a percolation structure among them, forming an approximate network-like conductive network, synergistically optimizing the proportion of the conductive channels formed by the carbon black particles and the percolation structure, and having excellent conductive performance.

[0200] Among them, the carbon black content in Example 3 is relatively low, and the volume resistivity is relatively high; in the semiconductive shielding material prepared in Example 6, the content of the hydroxylated propylene-based copolymer resin of the propylene-based copolymer resin matrix A5 is relatively low, thus having a certain influence on the dispersion of the carbon black particles, and further affecting the conductivity of the material; the material of Comparative Example 2 does not contain the propylene-based copolymer resin matrix of the present invention, and Comparative Example 3 uses a block copolymerized polypropylene resin, and the measured resistivity is relatively large, unable to achieve the technical effect of the present invention.

[0201] Table 3: Test Results of Volume Resistivity of Semiconducting Shielding Material at 90°C

[0202] Sample Volume resistivity (Ω·cm) Example 1 40.2 Example 2 32.4 Example 3 425.7 Example 4 36.2 Example 5 37.8 Example 6 67.1 Comparative Example 1 33.4 Comparative Example 2 2405 Comparative Example 3 875

[0203] As can be seen from the test results of the volume resistivity of the semiconducting shielding material at 90°C in Table 3, due to the expansion effect of the matrix at high temperatures, the distance between the conductive fillers will increase. Therefore, the increase in temperature will have a negative impact on the conductivity of the shielding material. At 90°C, the resistivity temperature sensitivity of the semiconducting shielding materials prepared in Examples 1-6 of the present invention is relatively low, while the resistivity of the semiconducting shielding materials prepared in Comparative Examples 2-3 increases significantly, and the conductivity decreases significantly.

[0204] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0205] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent shall be subject to the appended claims.

Claims

1. An allyl copolymer resin matrix, characterized in that, The propylene-based copolymer resin matrix is prepared from a hydroxylated propylene-based copolymer resin, a polyisocyanate, a polyol oligomer, and a chain extender. The hydroxyl content in the hydroxylated propylene-based copolymer resin is 0.2-3 mol%.

2. The propylene-based copolymer resin matrix according to claim 1, characterized in that, The propylene-based copolymer resin matrix satisfies at least one of the following (1)-(9): (1) In the preparation process, the mass ratio of the hydroxylated propylene-based copolymer resin to the sum of the three components including the polyisocyanate, the polyol oligomer, and the chain extender is (40-100):(20-70); (2) In the preparation process, the molar ratio of the hydroxyl group content in the hydroxylated propylene-based copolymer resin to the isocyanate group in the polyisocyanate is (0.1-2):(0.5-3); (3) In the preparation process, the mass ratio of the polyisocyanate, the polyol oligomer, and the chain extender is (0.5-5):(0.2-4):(0.2-4); (4) The hydroxylated propylene-based copolymer resin in the preparation process is selected from one or more of ZKKY PP200, GI-2000, Krasol LBH-2000, SCRSTANDARD SCPP-80517, and BASF P188; (5) The polyisocyanate in the preparation process is selected from one or more of 4,4'-methylenebis(phenyl isocyanate), 4,4-diisocyanatodicyclohexylmethane, isophorone diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate; (6) The polyol oligomer in the preparation process is selected from one or more of polycaprolactone diol, polytetrahydrofuran, polycarbonate diol, and polypropylene oxide diol; (7) The chain extender in the preparation process is selected from one or more of 1,4-butanediol, ethylenediamine, ethylene glycol, and hydroquinone bis(β-hydroxyethyl) ether; (8) The number average molecular weight of the propylene-based copolymer resin matrix is 80,000-100,000; (9) The melt flow rate of the propylene-based copolymer resin matrix is 0.1 g / 10 min - 3 g / 10 min.

3. The propylene-based copolymer resin matrix according to claim 1 or 2, characterized in that, The structural general formula of the propylene-based copolymer resin matrix is: In the formula: the x segment is a structure derived from the hydroxylated propylene-based copolymer resin or the polyol oligomer, or a structure obtained by polymerization of the hydroxylated propylene-based copolymer resin and the polyol oligomer; the y segment is a structure obtained by polymerization of the polyisocyanate and the chain extender; where x is 3-40 and y is 100-240.

4. A method for preparing the propylene-based copolymer resin matrix according to any one of claims 1-3, comprising the following steps: Mix the polyol oligomer with the hydroxylated propylene-based copolymer resin, add the polyisocyanate and a catalyst under a nitrogen atmosphere, carry out a prepolymerization reaction to obtain a prepolymerized material, and add the chain extender to the prepolymerized material to carry out a chain extension reaction to obtain the propylene-based copolymer resin matrix.

5. A semiconductive shielding material, characterized in that, The semi-conductive shielding material comprises the propylene-based copolymer resin matrix according to any one of claims 1-3, or comprises the propylene-based copolymer resin matrix prepared by the preparation method according to claim 4.

6. The semi-conductive shielding material according to claim 5, characterized in that, The semi-conductive shielding material further contains conductive fillers, and the mass ratio of the propylene-based copolymer resin matrix to the conductive fillers is (50-100):(15-50).

7. The semi-conductive shielding material according to claim 5 or 6, characterized in that, The semi-conductive shielding material further contains additives, and the additives include at least one of the following (1)-(4); (1) The additive is an antioxidant selected from one or more of antioxidant 1010, antioxidant 1035, and antioxidant 300; kinds of antioxidants; (2) The additive is an anti-copper agent selected from one or more of anti-copper agent 1024, Irgafos 168, Chimassorb 944, and Tinuvin 770; (3) The additive is a lubricant selected from one or more of silicone masterbatch, stearic acid, pentaerythritol stearate, polyethylene wax, and oxidized polyethylene wax; (4) The mass ratio of the propylene-based copolymer resin matrix in the semi-conductive shielding material to the additive is 100:(0.01-5).

8. A shielding layer comprising the semi-conductive shielding material according to any one of claims 5 to 7.

9. A cable, characterized in that, It includes a conductor, and the shielding layer, insulating layer, and protective sheath according to claim 8 sequentially coated on the surface of the conductor.

10. The cable according to claim 9, characterized in that, The insulating layer is a polypropylene insulating layer; and / or, the cable is a high-voltage DC cable with a voltage reaching 220 kV or above.

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