Environment-friendly semi-conductive shielding material and preparation method and application thereof

Abstract

The invention belongs to the technical field of polymers, and discloses an environment-friendly semi-conductive shielding material and a preparation method and application thereof, the semi-conductive shielding material contains a propylene polymer, a conductive filler and an antioxidant; the propylene polymer contains a functional monomer graft modified or unmodified first propylene polymer and an optional functional monomer graft modified second propylene polymer, the tensile strength of the first propylene polymer is less than 20 MPa, and the tensile strength of the second propylene polymer is greater than 20 MPa; the semi-conductive shielding material comprises the following components in percentage by weight: 10-80% of a grafted modified or unmodified first propylene polymer, 0-60% of a grafted modified second propylene polymer, 15-45% of a conductive filler and 1-10% of a grafted functional monomer structural unit in the semi-conductive shielding material. The semi-conductive shielding material has good mechanical performance and conductive performance, and when the semi-conductive shielding material is used as a shielding layer, the electric field distortion rate of an insulating layer is low.

Description

Technical Field

[0001] This invention belongs to the field of polymer technology, specifically relating to an environmentally friendly semiconductive shielding material, a method for preparing the environmentally friendly semiconductive shielding material, and the application of the environmentally friendly semiconductive shielding material. Background Technology

[0002] Solving the problem of power transmission channels, and delivering large-capacity electrical energy to users, is one of the major issues that urgently need to be addressed in the development of the power industry. To address this problem, my country has established the basic development direction of constructing and developing ultra-high voltage and large-capacity AC / DC transmission systems.

[0003] Traditional extruded DC cables typically use cross-linked polyethylene (XLPE) as the cable insulation material. However, many problems have been exposed during production and operation: the maximum operating temperature of the cable can reach 90℃, but the maximum operating temperature of existing XLPE cables is only 70℃; the cross-linking process produces byproducts, exacerbating charge accumulation and electric field distortion.

[0004] Power cables are mainly composed of a metallic conductor, a conductor shielding layer, an insulation layer, an insulation shielding layer, and protective materials. To meet the requirements of environmental protection and sustainable development, research on novel recyclable non-crosslinked polyolefin cable insulation materials has become a hot topic in insulation materials. Polypropylene, with its excellent motor performance and low price, has become the most popular research direction. Researching environmentally friendly semi-conductive shielding materials compatible with polypropylene insulation materials is also of great significance. Furthermore, to adapt to the application trends of high current carrying capacity and extreme environments in cables, developing a green and environmentally friendly semi-conductive shielding material with good mechanical properties, stable conductivity, and resistance to space charge injection has high practical value. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, the purpose of this invention is to provide an environmentally friendly semiconductive shielding material, its preparation method, and its applications. This environmentally friendly semiconductive shielding material possesses good mechanical properties, excellent electrical conductivity, and, when used as a shielding layer, is resistant to charge injection, while exhibiting low electric field distortion of the insulating layer.

[0006] The first aspect of the present invention provides an environmentally friendly semiconductive shielding material comprising a propylene polymer, a conductive filler, and an antioxidant; wherein the propylene polymer comprises a first propylene polymer grafted with functional monomers or unmodified and a second propylene polymer grafted with functional monomers, wherein the tensile strength of the first propylene polymer is less than 20 MPa and the tensile strength of the second propylene polymer is greater than 20 MPa.

[0007] Based on the total weight of the propylene polymer and the conductive filler, the content of the first propylene polymer, which is grafted or unmodified with the functional monomer, is 10-80 wt%, the content of the second propylene polymer, which is grafted with the functional monomer, is 0-60 wt%, the content of the conductive filler is 15-45 wt%, and the content of the functional monomer structural unit in the grafted state in the semi-conductive shielding material is 1-10 wt%.

[0008] A second aspect of the present invention provides a method for preparing the above-mentioned environmentally friendly semiconductive shielding material, the method comprising the following steps:

[0009] S1: Optionally, prepare a first propylene polymer grafted with a functional monomer by subjecting a reaction mixture including the first propylene polymer and the functional monomer to a grafting reaction in the presence of an inert gas to obtain the first propylene polymer grafted with a functional monomer.

[0010] Optionally, a second propylene polymer modified by grafting functional monomers is prepared by subjecting a reaction mixture including the second propylene polymer and the functional monomers to a grafting reaction in the presence of an inert gas to obtain the second propylene polymer modified by grafting functional monomers.

[0011] S2: Mix the materials containing a first propylene polymer grafted with functional monomers or unmodified, a second propylene polymer grafted with optional functional monomers, conductive fillers, and antioxidants, and melt-extrude and granulate to obtain the semi-conductive shielding material.

[0012] A third aspect of the present invention provides the application of the above-mentioned environmentally friendly semiconductive shielding material in the field of cable semiconductive shielding.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The semiconductive shielding material of the present invention has good mechanical properties, excellent and stable conductivity, and when used as a shielding layer, the insulation layer has a low electric field distortion rate. The semiconductive shielding material of the present invention is non-crosslinked, green and environmentally friendly, and can be used in conjunction with polypropylene-based insulation materials, which meets the application trend of high current carrying capacity and extreme environment of cables.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0016] 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.

[0017] According to a first aspect of the present invention, the present invention provides an environmentally friendly semiconductive shielding material comprising a propylene polymer, a conductive filler, and an antioxidant; wherein the propylene polymer comprises a first propylene polymer grafted with functional monomers or unmodified and a second propylene polymer grafted with functional monomers, wherein the tensile strength of the first propylene polymer is less than 20 MPa and the tensile strength of the second propylene polymer is greater than 20 MPa.

[0018] Based on the total weight of the propylene polymer and the conductive filler, the content of the first propylene polymer, which is grafted or unmodified with the functional monomer, is 10-80 wt%, the content of the second propylene polymer, which is grafted with the functional monomer, is 0-60 wt%, the content of the conductive filler is 15-45 wt%, and the content of the functional monomer structural unit in the grafted state in the semi-conductive shielding material is 1-10 wt%.

[0019] In a preferred embodiment, based on the total weight of the propylene polymer and the conductive filler, the content of the first propylene polymer, which is grafted or unmodified with the functional monomer, is 15-65 wt%, preferably 18-55 wt%; the content of the second propylene polymer, which is grafted with the functional monomer, is 10-55 wt%, preferably 12-40 wt%; the content of the conductive filler is 18-35 wt%; and the content of the functional monomer structural units in the grafted state in the semiconductive shielding material is 2-5 wt%.

[0020] In this invention, the semiconductive shielding material has at least one of the following characteristics: a melt flow rate of 0.01-3 g / 10 min, more preferably 0.01-1 g / 10 min, at 230°C and a load of 2.16 kg; and a melting temperature Tm of 110-180°C, more preferably 120-170°C.

[0021] According to the present invention, the semiconductive shielding material has a volume resistivity of no more than 35 Ω·cm, preferably no more than 25 Ω·cm, at 20°C; a volume resistivity of no more than 240 Ω·cm, preferably no more than 160 Ω·cm, at 105°C; and a temperature coefficient of resistance (TCR) of no more than 0.06°C at 105°C. -1 The electric field distortion rate is not greater than 10%, preferably not greater than 5%; the tensile strength of the semiconductive shielding material is 5-28 MPa, preferably 10-25 MPa; the elongation at break is 50-800%, preferably 100-600%.

[0022] The functional monomers of the present invention contain alkenyl groups, which can be grafted onto propylene polymers. Therefore, any alkenyl-containing functional monomers with alkenyl groups located in reactive positions are applicable to the present invention.

[0023] Specifically, the functional monomer may be selected from at least one of the monomers having the structure shown in formula (1).

[0024]

[0025] In equation (1), R b R c R d Each is independently selected from H, substituted or unsubstituted alkyl groups; R a It is selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, substituted or unsubstituted ester, substituted or unsubstituted carboxyl, substituted or unsubstituted cycloalkyl or heterocyclic, cyano, substituted or unsubstituted silyl.

[0026] Preferably, R b R c R d Each is independently selected from H, substituted or unsubstituted C1-C6 alkyl groups; R a Selected from substituted or unsubstituted C1-C 20 Alkyl, substituted or unsubstituted C1-C 20 Alkoxy, substituted or unsubstituted C6-C 20 aryl, substituted or unsubstituted C1-C 20 Ester group, substituted or unsubstituted C1-C 20 Carboxyl, substituted or unsubstituted C3-C 20 Cycloalkyl or heterocyclic, cyano, substituted or unsubstituted C3-C 20 Silyl group; the substituted group is halogen, hydroxyl, amino, C1-C 12 Alkyl, C3-C6 cycloalkyl, C1-C 12 alkoxy groups, C1-C 12 Acyloxy group.

[0027] More preferably, R b R c R d Each is independently selected from H, substituted or unsubstituted C1-C6 alkyl groups; R a Selected from the group shown in formula (2), the group shown in formula (3), the group shown in formula (4), the group shown in formula (5), the group shown in formula (6), a combination of the group shown in formula (6) and the group shown in formula (7), and heterocyclic groups.

[0028]

[0029] In equation (2), R 4 -R 8 Each is independently selected from H, halogen, hydroxyl, amino, phosphate group, sulfonic acid group, substituted or unsubstituted C1-C.12 Alkyl, substituted or unsubstituted C3-C 12 cycloalkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 ester group, substituted or unsubstituted C1-C 12 The substituted amino group, wherein the substituted group is selected from halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C 12 Alkyl, C3-C 12 cycloalkyl, C1-C 12 alkoxy groups, C1-C 12 ester group, C1-C 12 The amino group; preferably, R 4 -R 8 Each is independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy.

[0030]

[0031] In equation (3), R4-R 10 Each is independently selected from H, halogen, hydroxyl, amino, phosphate group, sulfonic acid group, substituted or unsubstituted C1-C. 12 Alkyl, substituted or unsubstituted C3-C 12 cycloalkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 ester group, substituted or unsubstituted C1-C 12 The substituted amino group, wherein the substituted group is selected from halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C 12 Alkyl, C3-C 12 cycloalkyl, C1-C 12 alkoxy groups, C1-C 12 ester group, C1-C 12 The amino group; preferably, R4-R 10 Each of the groups is independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, wherein the substituted group is selected from halogen, hydroxyl, amino, C1-C6 alkyl, C1-C6 alkoxy.

[0032]

[0033] In equation (4), R4'-R 10 Each group is independently selected from H, halogen, hydroxyl, amino, phosphate, sulfonic acid, substituted or unsubstituted C1-C. 12 Alkyl, substituted or unsubstituted C3-C12 cycloalkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 ester group, substituted or unsubstituted C1-C 12 The substituted amino group, wherein the substituted group is selected from halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C 12 Alkyl, C3-C 12 cycloalkyl, C1-C 12 alkoxy groups, C1-C 12 ester group, C1-C 12 The amino group; preferably, R4'-R 10 Each of the groups is independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, wherein the substituted group is selected from halogen, hydroxyl, amino, C1-C6 alkyl, C1-C6 alkoxy.

[0034]

[0035] In equation (5), R', R”, and R”' are each independently selected from substituted or unsubstituted C1-C. 12 Straight-chain alkyl, substituted or unsubstituted C3-C 12 Branched alkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 The acyloxy group; preferably, R', R'', R''' are each independently selected from substituted or unsubstituted C1-C6 straight-chain alkyl groups, substituted or unsubstituted C3-C6 branched alkyl groups, substituted or unsubstituted C1-C6 alkoxy groups, and substituted or unsubstituted C1-C6 acyloxy groups.

[0036]

[0037] In equation (6), R m Selected from the following groups, substituted or unsubstituted: C1-C 20 Straight-chain alkyl, C3-C 20 Branched alkyl, C3-C 12 cycloalkyl, C3-C 12 Epoxyalkyl, C3-C 12 Epoxyalkyl alkyl, wherein the substituted group is selected from at least one of halogen, amino, and hydroxyl groups. Wherein C3-C 12 Epoxyalkyl refers to an alkyl group that has 3-12 carbon atoms and is substituted with an epoxyalkyl group, such as ethylene oxide methyl.

[0038] The heterocyclic group can be selected from imidazole, pyrazol, carbazole, pyrrolidone, pyridinyl, piperidinyl, caprolactam, pyrazinyl, thiazolyl, purine, morpholino, and oxazolino.

[0039] In a preferred embodiment, the functional monomer is selected from aromatic olefin monomers, alkenyl-containing silane monomers, acrylate monomers, and optionally acrylic monomers.

[0040] Specifically, the aromatic olefin monomer may be selected from at least one of styrene, α-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, monosubstituted or polysubstituted styrene, monosubstituted or polysubstituted α-methylstyrene, monosubstituted or polysubstituted 1-vinylnaphthalene, and monosubstituted or polysubstituted 2-vinylnaphthalene. The substituted group is preferably selected from at least one of halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C8 straight-chain alkyl, C3-C8 branched alkyl or cycloalkyl, C1-C6 straight-chain alkoxy, C3-C8 branched alkoxy or cyclic alkoxy, C1-C8 straight-chain ester, C3-C8 branched ester or cyclic ester, C1-C8 straight-chain amino, and C3-C8 branched amino or cyclic amino; more preferably, the aromatic olefin monomer is selected from at least one of styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, and 4-methylstyrene.

[0041] The alkenyl-containing silane monomer may be selected from at least one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriisopropoxysilane, vinyltritert-butoxysilane, vinyltriacetoxysilane, methylvinyldimethoxysilane, ethylvinyldiethoxysilane, allyltriethoxysilane, allyltrimethoxysilane, allyltriisopropoxysilane, vinyltri(β-methoxyethoxy)silane, allyltri(β-methoxyethoxy)silane, allyltritert-butoxysilane, allyltriacetoxysilane, methylallyldimethoxysilane, and ethylallyldiethoxysilane.

[0042] The acrylate monomers may be selected from at least one of methyl methacrylate, sec-butyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, coconut oil ester methacrylate, octadecyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminopropyl methacrylate, and glycidyl methacrylate.

[0043] The acrylic monomer may be selected from at least one of acrylic acid, methacrylic acid and 2-ethylacrylic acid.

[0044] In this invention, the structural units derived from acrylic monomers may be absent or may coexist with the structural units derived from acrylate monomers. When the functional monomer is an acrylate monomer or optionally an acrylic monomer, the molar ratio of the structural units derived from acrylate monomers to the structural units derived from acrylic monomers may be 1:0-2, preferably 1:0.125-1.

[0045] According to the present invention, the functional monomer can be an alkenyl-containing heterocyclic compound, which can be any alkenyl-containing heterocyclic compound capable of free radical polymerization, and can be selected from at least one of alkenyl-substituted imidazole, alkenyl-substituted pyrazole, alkenyl-substituted carbazole, alkenyl-substituted pyrrolidone, alkenyl-substituted pyridine or pyridine salt, alkenyl-substituted piperidine, alkenyl-substituted caprolactam, alkenyl-substituted pyrazine, alkenyl-substituted thiazole, alkenyl-substituted purine, alkenyl-substituted morpholine, and alkenyl-substituted oxazoline; preferably, the alkenyl-containing heterocyclic monomer is a monoalkenyl-containing heterocyclic monomer.

[0046] Specifically, the alkenyl-containing heterocyclic monomer may be selected from at least one of the following: 1-vinylimidazolium, 2-methyl-1-vinylimidazolium, N-allylimidazolium, 1-vinylpyrazole, 3-methyl-1-vinylpyrazole, vinylcarbazole, N-vinylpyrrolidone, 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, vinylpyridine N-oxide, vinylpyridine salt, vinylpiperidine, N-vinylcaprolactam, 2-vinylpyrazine, N-vinylpiperazine, 4-methyl-5-vinylthiazole, N-vinylpurine, vinylmorpholine, and vinyloxazoline.

[0047] In this invention, the term "structural unit" refers to a part of a propylene polymer grafted with a functional monomer, and its form is not limited. Specifically, "functional monomer structural unit" and "structural unit derived from functional monomer" refer to products formed from functional monomers, which include products in the form of "groups," "monomers," and "polymers"; "structural unit derived from propylene polymer" refers to products formed from propylene polymers, which include products in the form of "groups" and "polymers." The "structural unit" can be a repeating unit or a non-repeating independent unit.

[0048] According to the present invention, the first propylene polymer and the second propylene polymer modified by functional monomer grafting include structural units derived from the first propylene polymer or the second propylene polymer and structural units derived from the functional monomer; based on the weight of the first propylene polymer or the second propylene polymer modified by functional monomer grafting, the content of structural units derived from the functional monomer and in the grafted state in the first propylene polymer or the second propylene polymer modified by functional monomer grafting is 2-35 wt%, preferably 5-30 wt%.

[0049] According to the present invention, the first propylene polymer can be impact-resistant polypropylene, the concept of which is well known to those skilled in the art. The first propylene polymer is preferably an ethylene-propylene copolymer with a tensile strength of less than 20 MPa. Specifically, the ethylene-propylene copolymer contains a propylene homopolymer or propylene random copolymer matrix component (1) as the matrix phase, and another propylene copolymer component (2) dispersed therein as the dispersed phase. The propylene copolymer component contains one or more ethylene or higher α-olefin comonomers. In the propylene random copolymer, the comonomers are randomly distributed on the main chain of the propylene polymer. Preferably, the propylene copolymer (2) dispersed in the homopolymer or copolymer matrix (1) of the ethylene-propylene copolymer is substantially amorphous. The term "substantially amorphous" here means that the propylene copolymer (2) has a lower crystallinity than the homopolymer or copolymer matrix (1).

[0050] The ethylene-propylene copolymer can have an island structure or a bicontinuous structure. Preferably, the ethylene-propylene copolymer of the present invention is a multiphase propylene copolymer prepared in situ in a reactor using existing processes.

[0051] According to the present invention, preferably, the ethylene-propylene copolymer has at least one of the following characteristics: a comonomer content of 8-25 wt%, preferably 10-22 wt%; a xylene-soluble content of 15-75 wt%, preferably 25-70 wt%; a melt flow rate of 0.01-15 g / 10 min at 230°C and 2.16 kg load, preferably 0.1-7 g / 10 min; a melt temperature Tm of 120-165°C, more preferably 125-150°C; a tensile strength of less than 20 MPa; and a xylene-soluble comonomer content of 10-50 wt%, preferably 15-35 wt%.

[0052] The ethylene-propylene copolymers described in this invention include, but are not limited to, any commercially available polypropylene powders and granules suitable for this invention, and can also be produced by the polymerization processes described in patent documents CN1081683, CN1108315, CN1228096, CN1281380, CN1132865C, and CN102020733A. Commonly used polymerization processes include Basell's Spheripo1 process, Mitsui Chemicals' Hypol process, Borealis' Borstar PP process, Dow Chemical's Unipol process, and INEOSCO's (formerly BP-Amoco) Innovene gas-phase process, etc.

[0053] In this invention, the second propylene polymer can be homopolymer or copolymer polypropylene, and the second propylene polymer has at least one of the following characteristics: a comonomer content of 0-15 mol%, preferably 0-12 mol%, more preferably 0-8 mol%; a melt flow rate of 0.01-10 g / 10 min at 230°C and 2.16 kg load, preferably 0.1-5 g / 10 min; a melt temperature Tm of 110-180°C, more preferably 120-170°C; and a weight-average molecular weight of 20 × 10⁻⁶. 4 -50×10 4 g / mol; tensile strength greater than 20 MPa.

[0054] According to the present invention, the comonomer of the copolymerized polypropylene may be selected from at least one of C2-C8 α-olefins other than propylene. Preferably, the comonomer of the copolymerized polypropylene is selected from at least one of ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, and 1-octene. More preferably, the comonomer of the copolymerized polypropylene is ethylene and / or 1-butene. The copolymerized polypropylene of the present invention is preferably a porous granular or powdered resin.

[0055] The homopolymer or copolymer polypropylene described in this invention can be any commercially available polypropylene powder suitable for this invention, or it can be produced by the polymerization process described in patent documents CN102453180B, CN101490096B, CN102816269B, CN102816270B, etc.

[0056] In this invention, the conductive filler may be selected from one or more of conductive carbon black, carbon nanotubes, graphene, and MXene, preferably conductive carbon black, and more preferably acetylene black.

[0057] Preferably, the acetylene black has an oil absorption value of not less than 120cc / 100g, an iodine absorption value of not less than 70mg / g, and a residue of not more than 25ppm on a 325-mesh sieve.

[0058] According to a second aspect of the present invention, the present invention provides a method for preparing the above-mentioned environmentally friendly semiconductive shielding material, the method comprising the following steps:

[0059] S1: Optionally, prepare a first propylene polymer grafted with a functional monomer by subjecting a reaction mixture including the first propylene polymer and the functional monomer to a grafting reaction in the presence of an inert gas to obtain the first propylene polymer grafted with a functional monomer.

[0060] Optionally, a second propylene polymer modified by grafting functional monomers is prepared by subjecting a reaction mixture including the second propylene polymer and the functional monomers to a grafting reaction in the presence of an inert gas to obtain the second propylene polymer modified by grafting functional monomers.

[0061] S2: Mix the materials containing a first propylene polymer grafted with functional monomers or unmodified, a second propylene polymer grafted with optional functional monomers, conductive fillers, and antioxidants, and melt-extrude and granulate to obtain the semi-conductive shielding material.

[0062] In this invention, the first propylene polymer and the second propylene polymer modified by functional monomer grafting can be prepared by similar methods, and the functional monomers and other materials used can be the same.

[0063] According to one specific embodiment, the preparation method of the semiconductive shielding material includes the following steps:

[0064] a. Place the first propylene polymer or the second propylene polymer in a closed reactor and replace it with an inert gas;

[0065] b. Add the free radical initiator and functional monomer to the closed reactor and stir to mix;

[0066] c. Optionally add an interfacial agent and optionally swell the reaction system;

[0067] d. Optionally add a dispersant to raise the temperature of the reaction system to the grafting reaction temperature and carry out the grafting reaction;

[0068] e. Optionally, filter the product and place it in a vacuum or inert gas environment to heat and devolatilize it to obtain a first propylene polymer or a second propylene polymer grafted with functional monomers.

[0069] The first propylene polymer and the second propylene polymer modified with functional monomers were optionally prepared by the ae step.

[0070] f. The first propylene polymer, grafted with functional monomers or unmodified, and the second propylene polymer, optionally grafted with functional monomers, conductive filler, antioxidant, and optional other additives are granulated by melt screw extrusion through a reciprocating single-screw compounding extruder or a twin-screw extruder to obtain the semi-conductive shielding material.

[0071] In this invention, the reaction mixture contains a free radical initiator, which may be selected from peroxide-based free radical initiators and / or azo-based free radical initiators. Preferably, the grafting site is initiated by a peroxide-based free radical initiator, and the grafting reaction is further carried out.

[0072] According to the present invention, the mass ratio of the free radical initiator to the functional monomer can be 0.01-10:100, preferably 0.5-5:100.

[0073] Specifically, the peroxide-based free radical initiator may be selected from at least one of benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, dodecyl peroxide, tert-butyl peroxide, diisopropyl peroxide, tert-butyl peroxide (2-ethylhexanoate), and dicyclohexyl peroxide.

[0074] Furthermore, the grafting reaction of the present invention can also be carried out by the methods described in CN106543369A, CN104499281A, CN102108112A, CN109251270A, CN1884326A and CN101492517B.

[0075] The present invention does not particularly limit the process conditions for the grafting reaction. Preferably, the grafting reaction is a solid-phase grafting reaction or a suspension grafting reaction. Specifically, the temperature of the grafting reaction is 30-130℃, preferably 60-120℃; the time is 0.5-10 hours, preferably 1-6 hours.

[0076] In this invention, the "reaction mixture" includes all materials added to the grafting reaction system. The materials can be added all at once or at different stages of the reaction.

[0077] The reaction mixture of the present invention includes a dispersant, preferably an aqueous solution of water or sodium chloride. The mass amount of the dispersant is preferably 50-300% of the mass of the propylene polymer.

[0078] The reaction mixture of the present invention includes an interface agent, which is an organic solvent that has a swelling effect on polyolefins. Preferably, it is at least one of the following organic solvents that have a swelling effect on propylene polymers: ether solvents, ketone solvents, aromatic solvents, and alkane solvents. More preferably, it is at least one of the following organic solvents: chlorobenzene, polychlorinated benzene, alkanes or cycloalkanes with more than 6 carbon atoms, benzene, C1-C4 alkyl-substituted benzene, C2-C6 aliphatic ethers, C3-C6 aliphatic ketones, and decahydronaphthalene. Further preferably, it is at least one of the following organic solvents: benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, diethyl ether, acetone, hexane, cyclohexane, decahydronaphthalene, and heptane. The mass content of the interface agent is preferably 1-30% of the mass of the propylene polymer, and more preferably 10-25%.

[0079] The reaction mixture of the present invention may each independently include an organic solvent as a solvent for dissolving the solid free radical initiator. The organic solvent preferably includes at least one of C2-C5 alcohols, C2-C4 ethers, and C3-C5 ketones; more preferably, it includes at least one of C2-C4 alcohols, C2-C3 ethers, and C3-C5 ketones; and most preferably, it includes at least one of ethanol, diethyl ether, and acetone. The mass content of the organic solvent is preferably 1-35% of the mass of the propylene polymer.

[0080] According to the present invention, if volatile components are present in the system after the reaction, the method of the present invention preferably includes a step of removing the volatiles, which can be carried out by any conventional method, including vacuum extraction or the use of a stripping agent at the end of the grafting process. Suitable stripping agents include, but are not limited to, inert gases.

[0081] As described above, the "functional monomer graft-modified first propylene polymer or second propylene polymer" of the present invention includes both the product (crude product) directly obtained from the first propylene polymer or second propylene polymer and the functional monomer through a grafting reaction, and the pure graft-modified first propylene polymer or second propylene polymer obtained by further purification of the product. Therefore, the preparation method of the present invention may optionally include a step of purifying the crude product. The purification can be carried out using various methods conventional in the art, such as extraction.

[0082] This invention does not impose a particular limitation on the grafting efficiency of the grafting reaction, but a higher grafting efficiency is more advantageous for obtaining functional monomer-grafted modified propylene polymer materials with the desired properties through a one-step grafting reaction. Therefore, it is preferable to control the grafting efficiency of the grafting reaction to be 20-100%, and more preferably 25-90%. The concept of grafting efficiency is well known to those skilled in the art, referring to the amount of functional monomer grafted onto the polymer and the total amount of functional monomers added to the reaction feed.

[0083] The inert gas described in this invention can be any of the inert gases commonly used in the art, including but not limited to nitrogen and argon.

[0084] The antioxidants of the present invention are selected from one or more of hindered phenols, hindered amines, phosphites, and thiocyanates, preferably from pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2′-methylenebis(4-methyl-6-tert-butylphenol), 2,4,6-tris(3′,5′-di-tert-butyl-4′-hydroxybenzyl)trimethylbenzene, 2,2′-thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2 One or more of the following: ',2-oxamido-bis-[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 4,4'-thiobis(6-tert-butyl-3-methylphenol), triphenyl phosphite, tris[2,4-di-tert-butylphenyl]phosphite, and dilauryl thiodipropionate.

[0085] In this invention, the antioxidant content in the resin and conductive filler mixture is greater than 2000 ppm, preferably 3000-15000 ppm.

[0086] According to the present invention, the other additives may be any one or more of the following: voltage stabilizers, antioxidants, copper inhibitors, processing aids, etc. The types and amounts of additives used are conventional and known to those skilled in the art.

[0087] The processing aids are fluorinated compounds, polypropylene wax, polyethylene wax, fatty acid esters, mineral oil, etc., preferably polypropylene wax, fatty acid esters and mineral oil.

[0088] The copper-resistant agent is preferably one or more of N,N′-bis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, 2,2-oxamido-bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionic acid, and N-salicylamidophthalimide.

[0089] In this invention, the amount of additive added can be 0.1-8% of the mass of the mixture of resin and conductive filler, preferably 0.2-5%.

[0090] According to the present invention, the melt extrusion temperature is 170-250°C, preferably 180-230°C, and more preferably 190-220°C.

[0091] According to a third aspect of the present invention, the present invention provides the application of the above-mentioned environmentally friendly semiconductive shielding material in the field of cable semiconductive shielding.

[0092] The substances and process parameters not limited in this invention can be selected according to existing technology, which are conventional technical means in this field.

[0093] The present invention will be further described below with reference to embodiments. However, the invention is not limited to these embodiments.

[0094] In the following embodiments and comparative examples, the data were obtained using the following methods:

[0095] 1. Determination of comonomer content in propylene polymers:

[0096] The content of comonomers was determined by quantitative Fourier transform infrared (FTIR) spectroscopy. The correlation of the determined comonomer content was calibrated by quantitative nuclear magnetic resonance (NMR) spectroscopy. Based on quantitative... 13 The calibration method for the C-NMR spectrometer results was performed according to conventional methods in the art.

[0097] 2. Determination of melt flow rate (melt index, MFR):

[0098] The test was performed using a CEAST 7026 melt flow indexer at 230°C and a load of 2.16 kg, according to the method specified in GB / T 3682-2018.

[0099] 3. Determination of melting temperature (melting point, Tm):

[0100] Differential scanning calorimetry (DSC) was used to analyze the melting and crystallization processes of the material. Specifically, under nitrogen protection, 5-10 mg of sample was heated from 20°C to 200°C using a three-stage temperature rise and fall measurement method. The change in heat flow reflected the melting and crystallization processes, and the melting temperature Tm was calculated.

[0101] 4. Determination of xylene-soluble content (XS):

[0102] The test shall be conducted according to the method specified in GB / T 24282-2009.

[0103] 5. Content X of functional monomer structural units in the grafted state in the semiconductive shielding material (based on the total weight of propylene polymer and conductive filler):

[0104] 2-4g of the grafted polypropylene product was placed in a Soxhlet extractor and extracted for 12 hours with an organic solvent (ethyl acetate for aromatic olefin monomers, acrylate monomers, and acid anhydrides; acetone for silane monomers) to remove unreacted monomers and their homopolymers, yielding a pure grafted product. The product was dried, weighed, and the content X of functional monomer structural units in the grafted state was calculated. In this invention, X is calculated using the following formula:

[0105]

[0106] In the above formula, W0 is the mass of the propylene-based polymer; W1 is the mass of the grafted product before extraction; W2 is the mass of the grafted product after extraction; m is the mass percentage of one of the propylene polymers in the total mass of the propylene polymer and the conductive filler, where A represents the first propylene polymer and B represents the second propylene polymer.

[0107] 6. Determination of DC volume resistivity:

[0108] The determination shall be carried out in accordance with the method specified in GB / T 1410-2006.

[0109] 7. Determination of electric field distortion rate:

[0110] Sample preparation method: Semiconductor shielding material was prepared into 1 mm thick sheets 1# and 2#. A 1 mm thick polypropylene insulating sheet was prepared. The semiconducting shielding material sample was placed on both sides of the polypropylene insulating sheet and hot-pressed at 200℃ and 5 MPa to form the test sample. The space charge distribution was characterized using the electroacoustic pulse method to test the electric field distortion rate. At 25℃, a DC electric field of 5 kV / mm was first applied to both sides of the test sample for 5 s to obtain the space charge distribution of the polypropylene insulating sample. Then, the voltage was increased to 40 kV / mm (DC electric field) and held for 60 min, and the injection and accumulation of charge in the polypropylene insulating sheet during this process were recorded. Subsequently, the sample was short-circuited to obtain the charge decay change during this process.

[0111] 8. Temperature resistivity (TCR)

[0112] In this invention, TCR (T) The calculation formula is as follows:

[0113] TCR (T) =(ρ T -ρ T0 ) / ρ T0 *(T-T0)

[0114] In the above formula, T0 is the ambient temperature (20℃); T is the test temperature; ρ T It is the volume resistivity of the material at the test temperature, ρ T0 Volume resistivity of a material at room temperature.

[0115] 9. Determination of tensile strength:

[0116] The determination shall be carried out in accordance with the method specified in GB / T 1040.2-2006.

[0117] 10. Determination of elongation at break:

[0118] The determination shall be carried out in accordance with the method specified in GB / T 1040.2-2006.

[0119] The sources and properties of the raw materials used in the examples and comparative examples are described in Table 1.

[0120] Table 1

[0121]

[0122]

[0123] Example 1

[0124] Weigh 2.0 kg of PP1 powder (after sieving to remove fine powder smaller than 40 mesh) and add it to a 10 L reactor equipped with a mechanical stirrer. Seal the reaction system and purge with nitrogen to remove oxygen. Add 3.5 g of benzoyl peroxide and 236.2 g of glycidyl methacrylate, stir and mix for 30 minutes, then add 2 kg of water as a dispersant. The mixture swells at 60 °C for 2 hours, then the temperature is raised to 90 °C and reacted for 4 hours. After the reaction is complete, cool the mixture, filter to remove the water dispersant, and vacuum dry at 70 °C for 10 hours to obtain the grafted polypropylene powder.

[0125] Polypropylene grafted powder, bPP, carbon black VXC500, 3000ppm antioxidant 1010 / 168 (mass ratio 1:1), 0.15% copper inhibitor 1024, and 0.3% processing aid 2602 were weighed according to a mass ratio of 35:37:28 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of polypropylene grafted powder, bPP, and carbon black VXC500). Granulation was performed using a reciprocating single-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 300rpm to obtain semi-conductive shielding material C1. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0126] Example 2

[0127] 2.0 kg of PPH-F03D powder (after sieving to remove fine powder smaller than 40 mesh) was weighed and added to a 10 L reactor equipped with a mechanical stirrer. The reaction system was sealed, and nitrogen was used for purging to remove oxygen. 7.4 g of benzoyl peroxide and 492.8 g of methyl methacrylate were added, and the mixture was stirred and mixed for 30 minutes. The mixture was then swollen at 45 °C for 1 hour, and the temperature was raised to 95 °C, and the reaction was continued for 3 hours. After the reaction was completed, the mixture was cooled and dried under vacuum at 70 °C for 10 hours to obtain the polypropylene grafted powder.

[0128] Polypropylene grafted powder, aPP, carbon black VXC500, 3000ppm antioxidant 1010 / 168 (mass ratio 1:1), 0.15% copper inhibitor 1024, and 0.3% processing aid 5920 were weighed according to a mass ratio of 20:50:30 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of polypropylene grafted powder, aPP, and carbon black VXC500). Granulation was performed using a reciprocating single-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 300rpm to obtain composite material C2. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0129] Example 3

[0130] Weigh 2.0 kg of 1801 powder (after sieving to remove fine powder smaller than 40 mesh) and add it to a 10 L reactor equipped with a mechanical stirrer. Seal the reaction system and purge with nitrogen to remove oxygen. Add 7.0 g of benzoyl peroxide and 464.3 g of trivinylsiloxane, stir and mix for 30 minutes, then add 4 kg of water as a dispersant. The mixture swells at 40°C for 2 hours, then the temperature is raised to 85°C and reacted for 6 hours. After the reaction is complete, cool the mixture, filter to remove the water dispersant, and vacuum dry at 70°C for 10 hours to obtain the polypropylene grafted powder.

[0131] Polypropylene grafted powder, bPP, carbon black VXC500, 3000ppm antioxidant 1010 / 168 / 1076 (mass ratio 1:1:1), 0.15% copper inhibitor 1024, and 0.3% processing aid 2602 were weighed according to a mass ratio of 18:52:30 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of polypropylene grafted powder, bPP, and carbon black VXC500). Granulation was performed using a reciprocating single-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 300rpm to obtain semi-conductive shielding material C3. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0132] Example 4

[0133] 2.0 kg of PP2 powder (after sieving to remove fine powder smaller than 40 mesh) was weighed and added to a 10 L reactor equipped with a mechanical stirrer. The reaction system was sealed, and nitrogen was used for purging to remove oxygen. 1.8 g of tert-butyl peroxide (2-ethylhexanoate) and 116.7 g of acrylic acid were added, and the mixture was stirred and mixed for 30 minutes. 2 kg of water (dispersant) was added, and the mixture was allowed to swell at 40 °C for 2 hours. The temperature was then raised to 90 °C, and the reaction was continued for 4 hours. After the reaction was completed, the mixture was cooled, filtered to remove the water (dispersant), and vacuum dried at 70 °C for 10 hours to obtain polypropylene grafted powder 1.

[0134] 2.0 kg of aPP powder, after sieving to remove fine powder smaller than 40 mesh, was weighed and added to a 10 L reactor equipped with a mechanical stirrer. The reaction system was sealed, and nitrogen was used for purging to remove oxygen. 1.9 g of tert-butyl peroxide (2-ethylhexanoate) and 123.5 g of acrylic acid were added, and the mixture was stirred and mixed for 30 minutes. 2 kg of water was added as a dispersant, and the mixture was allowed to swell at 40 °C for 2 hours. The temperature was then raised to 90 °C, and the reaction was continued for 4 hours. After the reaction was completed, the mixture was cooled, filtered to remove the water dispersant, and vacuum dried at 70 °C for 10 hours to obtain polypropylene grafted powder 2.

[0135] Polypropylene grafted powder 1, polypropylene grafted powder 2, carbon black VXC500, and 4000ppm antioxidant 1035, 0.15% copper inhibitor 1024, and 0.3% processing aid 2602 were weighed according to a mass ratio of 25:47:28 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of polypropylene grafted powder 1, polypropylene grafted powder 2, and carbon black VXC500). Granulation was performed using a reciprocating single-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 300rpm to obtain semi-conductive shielding material C4. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0136] Example 5

[0137] Weigh 2.0 kg of CPP powder (after sieving to remove fine powder smaller than 40 mesh) and add it to a 10 L reactor equipped with a mechanical stirrer. Seal the reaction system and purge with nitrogen to remove oxygen. Add 1.6 g of tert-butyl peroxide (2-ethylhexanoate) and 106.0 g of styrene, stir and mix for 50 minutes, add 2 kg of water as a dispersant, and allow to swell at 60 °C for 2 hours. Then raise the temperature to 90 °C and react for 4 hours. After the reaction is complete, cool the mixture, filter to remove the water dispersant, and vacuum dry at 70 °C for 10 hours to obtain the grafted polypropylene powder.

[0138] Polypropylene grafted powder, carbon black VXC500, 3000ppm antioxidant 1035, 0.15% copper inhibitor 1024, and 0.3% processing aid 2602 were weighed according to a mass ratio of 72:28 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of polypropylene grafted powder and carbon black VXC500). Granulation was performed using a reciprocating single-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 300rpm to obtain semi-conductive shielding material C5. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0139] Example 6

[0140] Weigh 2.0 kg of PP1 powder (after sieving to remove fine powder smaller than 40 mesh) and add it to a 10 L reactor equipped with a mechanical stirrer. Seal the reaction system and purge with nitrogen to remove oxygen. Add 2.5 g of benzoyl peroxide and 165.5 g of glycidyl methacrylate, stir and mix for 30 minutes, then add 2 kg of water as a dispersant. The mixture swells at 60 °C for 2 hours, then the temperature is raised to 90 °C and reacted for 4 hours. After the reaction is complete, cool the mixture, filter to remove the water dispersant, and vacuum dry at 70 °C for 10 hours to obtain the grafted polypropylene powder.

[0141] Polypropylene grafted powder, bPP, carbon black VXC500, 3000ppm antioxidant 1010 / 168 (mass ratio 1:1), 0.15% copper inhibitor 1024, and 0.3% processing aid 2602 were weighed according to a mass ratio of 42:30:28 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of polypropylene grafted powder, bPP, and carbon black VXC500). Granulation was performed using a reciprocating single-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 300rpm to obtain semi-conductive shielding material C6. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0142] Example 7

[0143] Weigh 2.0 kg of PP1 powder (after sieving to remove fine powder smaller than 40 mesh) and add it to a 10 L reactor equipped with a mechanical stirrer. Seal the reaction system and purge with nitrogen to remove oxygen. Add 8.9 g of benzoyl peroxide and 597.0 g of glycidyl methacrylate, stir and mix for 30 minutes, add 2 kg of water as a dispersant, and allow to swell at 60 °C for 2 hours. Then raise the temperature to 90 °C and react for 4 hours. After the reaction is complete, cool the mixture, filter to remove the water dispersant, and vacuum dry at 70 °C for 10 hours to obtain the grafted polypropylene powder.

[0144] Polypropylene grafted powder, bPP, carbon black VXC500, 3000ppm antioxidant 1010 / 168 (mass ratio 1:1), 0.15% copper inhibitor 1024, and 0.3% processing aid 2602 were weighed according to a mass ratio of 11:59:30 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of polypropylene grafted powder, bPP, and carbon black VXC500). Granulation was performed using a reciprocating single-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 300rpm to obtain semi-conductive shielding material C7. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0145] Example 8

[0146] The polypropylene grafted powder, bPP, carbon black VXC500, 3000ppm antioxidant 1010 / 168 / 1076 (mass ratio 1:1:1), 0.15% copper inhibitor 1024, and 0.3% processing aid 2602 from Example 3 were weighed according to a mass ratio of 18:52:30 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of polypropylene grafted powder, bPP, and carbon black VXC500). Granulation was performed using a twin-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 250rpm to obtain the semi-conductive shielding material C8. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0147] Example 9

[0148] Weigh 2.0 kg of PP1 powder (after sieving to remove fine powder smaller than 40 mesh) and add it to a 10 L reactor equipped with a mechanical stirrer. Seal the reaction system and purge with nitrogen to remove oxygen. Add 9.5 g of benzoyl peroxide and 617.5 g of glycidyl methacrylate, stir and mix for 30 minutes, then add 2 kg of water as a dispersant. The mixture swells at 60 °C for 2 hours, then the temperature is raised to 90 °C and reacted for 4 hours. After the reaction is complete, cool the mixture, filter to remove the water dispersant, and vacuum dry at 70 °C for 10 hours to obtain the grafted polypropylene powder.

[0149] Polypropylene grafted powder, bPP, carbon black VXC500, 3000ppm antioxidant 1010 / 168 (mass ratio 1:1), 0.15% copper inhibitor 1024, and 0.3% processing aid 2602 were weighed according to a mass ratio of 35:37:28 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of polypropylene grafted powder, bPP, and carbon black VXC500). Granulation was performed using a reciprocating single-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 300rpm to obtain semi-conductive shielding material C9. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0150] Comparative Example 1

[0151] PP1, bPP, carbon black VXC500, 3000ppm antioxidant 1010 / 168 (mass ratio 1:1), 0.15% copper inhibitor 1024, and 0.3% processing aid 2602 were weighed according to a mass ratio of 35:37:28 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of PP1, bPP, and carbon black VXC500). Granulation was performed using a reciprocating single-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 300rpm to obtain semi-conductive shielding material D1. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0152] Comparative Example 2

[0153] Weigh 2.0 kg of PPH-F03D powder (after sieving to remove fine powder smaller than 40 mesh) and add it to a 10 L reactor equipped with a mechanical stirrer. Seal the reaction system and purge with nitrogen to remove oxygen. Add 2.5 g of benzoyl peroxide and 172.0 g of methyl methacrylate, stir and mix for 30 minutes, swell at 45 °C for 1 hour, then raise the temperature to 95 °C and react for 3 hours. After the reaction is complete, cool and dry under vacuum at 70 °C for 10 hours to obtain the polypropylene grafted powder.

[0154] Polypropylene grafted powder, aPP, carbon black VXC500, 3000ppm antioxidant 1010 / 168 (mass ratio 1:1), 0.15% copper inhibitor 1024, and 0.3% processing aid 5920 were weighed according to a mass ratio of 20:50:30 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of polypropylene grafted powder, aPP, and carbon black VXC500). The mixture was granulated using a reciprocating single-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 300rpm to obtain composite material D2. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0155] Comparative Example 3

[0156] Weigh 2.0 kg of CPP powder (after sieving to remove fine powder smaller than 40 mesh) and add it to a 10 L reactor equipped with a mechanical stirrer. Seal the reaction system and purge with nitrogen to remove oxygen. Add 0.5 g of tert-butyl peroxide (2-ethylhexanoate) and 28.5 g of styrene, stir and mix for 50 minutes, then add 2 kg of water as a dispersant. The mixture swells at 60 °C for 2 hours, then the temperature is raised to 90 °C and reacted for 4 hours. After the reaction is complete, cool the mixture, filter to remove the water dispersant, and vacuum dry at 70 °C for 10 hours to obtain the grafted polypropylene powder.

[0157] Polypropylene grafted powder, carbon black VXC500, 3000ppm antioxidant 1035, 0.15% copper inhibitor 1024, and 0.3% processing aid 2602 were weighed according to a mass ratio of 72:28 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of polypropylene grafted powder and carbon black VXC500). Granulation was performed using a reciprocating single-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 300rpm to obtain semi-conductive shielding material D3. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0158] Comparative Example 4

[0159] Weigh 2.0 kg of PP1 powder (after sieving to remove fine powder smaller than 40 mesh) and add it to a 10 L reactor equipped with a mechanical stirrer. Seal the reaction system and purge with nitrogen to remove oxygen. Add 3.5 g of benzoyl peroxide and 236.2 g of glycidyl methacrylate, stir and mix for 30 minutes, then add 2 kg of water as a dispersant. The mixture swells at 60 °C for 2 hours, then the temperature is raised to 90 °C and reacted for 4 hours. After the reaction is complete, cool the mixture, filter to remove the water dispersant, and vacuum dry at 70 °C for 10 hours to obtain the grafted polypropylene powder.

[0160] Polypropylene grafted powder, carbon black VXC500, 3000ppm antioxidant 1010 / 168 (mass ratio 1:1), 0.15% copper inhibitor 1024, and 0.3% processing aid 2602 were weighed according to a mass ratio of 72:28 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of polypropylene grafted powder and carbon black VXC500). Granulation was performed using a reciprocating single-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 300rpm to obtain semi-conductive shielding material D4. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0161] Comparative Example 5

[0162] Weigh 2.0 kg of PP1 powder (after sieving to remove fine powder smaller than 40 mesh) and add it to a 10 L reactor equipped with a mechanical stirrer. Seal the reaction system and purge with nitrogen to remove oxygen. Add 13.6 g of benzoyl peroxide and 905.0 g of glycidyl methacrylate, stir and mix for 30 minutes, add 2 kg of water as a dispersant, and allow to swell at 60 °C for 2 hours. Then raise the temperature to 90 °C and react for 4 hours. After the reaction is complete, cool the mixture, filter to remove the water dispersant, and vacuum dry at 70 °C for 10 hours to obtain the grafted polypropylene powder.

[0163] Polypropylene grafted powder, bPP, carbon black VXC500, 3000ppm antioxidant 1010 / 168 (mass ratio 1:1), 0.15% copper inhibitor 1024, and 0.3% processing aid 2602 were weighed according to a mass ratio of 35:37:28 (the amounts of antioxidant, copper inhibitor, and processing aid are based on the total mass of polypropylene grafted powder, bPP, and carbon black VXC500). Granulation was performed using a reciprocating single-screw extruder at zone temperatures of 190-200-210-220-220-220-220-210-200℃ and a screw speed of 300rpm to obtain semi-conductive shielding material D5. The performance parameters of the obtained product were tested, and the results are shown in Table 2.

[0164] Table 2

[0165]

[0166]

[0167] Comparing the data of Example 1 and Comparative Example 1, it can be seen that the semiconductive shielding material without the introduction of functional monomers has a higher volume resistivity and a higher electric field distortion rate of the insulating layer when used as a shielding layer.

[0168] Comparing the data of Example 2 and Comparative Example 2, and Example 5 and Comparative Example 3, it can be seen that the semiconductive shielding material with a low amount of functional monomers has poor electrical performance, and its volume resistivity and the electric field distortion rate of the insulating layer are both high when used as a shielding layer.

[0169] Comparing the data of Example 1 and Comparative Example 4, it can be seen that when the semiconductive shielding material is mainly composed of propylene polymer modified with functional monomers, the mechanical properties of the semiconductive shielding material do not meet the requirements for use.

[0170] Comparing the data of Example 1 and Comparative Example 5, it can be seen that when the grafting content is too high, the electric field distortion rate of the insulation layer is too high when used as a shielding layer.

[0171] In summary, as can be seen from the data in Table 2, the semiconductive shielding material obtained by this invention not only has excellent electrical properties, but also good mechanical properties.

[0172] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An environmentally friendly semiconductive shielding material, characterized in that, This environmentally friendly semi-conductive shielding material contains a propylene polymer, conductive filler, and antioxidant; the propylene polymer contains a first propylene polymer grafted with functional monomers or unmodified and a second propylene polymer grafted with functional monomers, wherein the tensile strength of the first propylene polymer is less than 20 MPa and the tensile strength of the second propylene polymer is greater than 20 MPa. Based on the total weight of the propylene polymer and the conductive filler, the content of the first propylene polymer, which is grafted or unmodified with the functional monomer, is 10-80 wt%, the content of the second propylene polymer, which is grafted with the functional monomer, is 0-60 wt%, the content of the conductive filler is 15-45 wt%, and the content of the functional monomer structural unit in the grafted state in the semi-conductive shielding material is 1-10 wt%.

2. The environmentally friendly semiconductive shielding material according to claim 1, wherein, Based on the total weight of the propylene polymer and the conductive filler, the content of the first propylene polymer, which is grafted or unmodified with the functional monomer, is 15-65 wt%, preferably 18-55 wt%; the content of the second propylene polymer, which is grafted with the functional monomer, is 10-55 wt%, preferably 12-40 wt%; the content of the conductive filler is 18-35 wt%; and the content of the functional monomer structural units in the grafted state in the semi-conductive shielding material is 2-5 wt%. Preferably, the semiconductive shielding material has at least one of the following characteristics: a melt flow rate of 0.01-3 g / 10 min at 230°C and a load of 2.16 kg, more preferably 0.01-1 g / 10 min; and a melting temperature Tm of 110-180°C, more preferably 120-170°C.

3. The environmentally friendly semiconductive shielding material according to claim 1, wherein, The semiconductive shielding material has a volume resistivity of no more than 35 Ω·cm, preferably no more than 25 Ω·cm, at 20°C; a volume resistivity of no more than 240 Ω·cm, preferably no more than 160 Ω·cm, at 105°C; and a temperature coefficient of resistance (TCR) of no more than 0.06°C at 105°C. -1 When used as a shielding layer, the electric field distortion rate of the insulating layer is not greater than 10%, preferably not greater than 5%; the tensile strength of the semiconductive shielding material is 5-28 MPa, preferably 10-25 MPa; the elongation at break is 50-800%, preferably 100-600%.

4. The environmentally friendly semiconductive shielding material according to claim 1, wherein, The functional monomer is selected from at least one monomer having the structure shown in formula (1). In equation (1), R b R c R d Each is independently selected from H, substituted or unsubstituted alkyl groups; R a Selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, substituted or unsubstituted ester, substituted or unsubstituted carboxyl, substituted or unsubstituted cycloalkyl or heterocyclic, cyano, substituted or unsubstituted silyl; Preferably, R b R c R d Each is independently selected from H, substituted or unsubstituted C1-C6 alkyl groups; R a Selected from substituted or unsubstituted C1-C 20 Alkyl, substituted or unsubstituted C1-C 20 Alkoxy, substituted or unsubstituted C6-C 20 aryl, substituted or unsubstituted C1-C 20 Ester group, substituted or unsubstituted C1-C 20 Carboxyl, substituted or unsubstituted C3-C 20 Cycloalkyl or heterocyclic, cyano, substituted or unsubstituted C3-C 20 Silyl group; the substituted group is halogen, hydroxyl, amino, C1-C 12 Alkyl, C3-C6 cycloalkyl, C1-C 12 alkoxy groups, C1-C 12 Acyloxy group; More preferably, R b R c R b Each is independently selected from H, substituted or unsubstituted C1-C6 alkyl groups; R a Selected from the group shown in formula (2), the group shown in formula (3), the group shown in formula (4), the group shown in formula (5), the group shown in formula (6), a combination of the group shown in formula (6) and the group shown in formula (7), and heterocyclic groups; In equation (2), R 4 -R 8 Each is independently selected from H, halogen, hydroxyl, amino, phosphate group, sulfonic acid group, substituted or unsubstituted C1-C. 12 Alkyl, substituted or unsubstituted C3-C 12 cycloalkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 ester group, substituted or unsubstituted C1-C 12 The substituted amino group, wherein the substituted group is selected from halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C 12 Alkyl, C3-C 12 cycloalkyl, C1-C 12 alkoxy groups, C1-C 12 ester group, C1-C 12 The amino group; preferably, R 4 -R 8 Each is independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy; In equation (3), R4-R 10 Each is independently selected from H, halogen, hydroxyl, amino, phosphate group, sulfonic acid group, substituted or unsubstituted C1-C. 12 Alkyl, substituted or unsubstituted C3-C 12 cycloalkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 ester group, substituted or unsubstituted C1-C 12 The substituted amino group, wherein the substituted group is selected from halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C 12 Alkyl, C3-C 12 cycloalkyl, C1-C 12 alkoxy groups, C1-C 12 ester group, C1-C 12 The amino group; preferably, R4-R 10 Each of the groups is independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, wherein the substituted group is selected from halogen, hydroxyl, amino, C1-C6 alkyl, C1-C6 alkoxy; In equation (4), R4'-R 10 Each group is independently selected from H, halogen, hydroxyl, amino, phosphate, sulfonic acid, substituted or unsubstituted C1-C. 12 Alkyl, substituted or unsubstituted C3-C 12 cycloalkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 ester group, substituted or unsubstituted C1-C 12 The substituted amino group, wherein the substituted group is selected from halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C 12 Alkyl, C3-C 12 cycloalkyl, C1-C 12 alkoxy groups, C1-C 12 ester group, C1-C 12 The amino group; preferably, R4'-R 10 Each of the following is independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, wherein the substituted group is selected from halogen, hydroxyl, amino, C1-C6 alkyl, C1-C6 alkoxy; In equation (5), R', R”, and R”' are each independently selected from substituted or unsubstituted C1-C. 12 Straight-chain alkyl, substituted or unsubstituted C3-C 12 Branched alkyl, substituted or unsubstituted C1-C 12 alkoxy, substituted or unsubstituted C1-C 12 The acyloxy group; preferably, R', R"', R"' are each independently selected from substituted or unsubstituted C1-C6 straight-chain alkyl, substituted or unsubstituted C3-C6 branched alkyl, substituted or unsubstituted C1-C6 alkoxy, substituted or unsubstituted C1-C6 acyloxy. In equation (6), R m Selected from the following groups, substituted or unsubstituted: C1-C 20 Straight-chain alkyl, C3-C 20 Branched alkyl, C3-C 12 cycloalkyl, C3-C 12 Epoxyalkyl, C3-C 12 Epoxyalkylalkyl, wherein the substituted group is selected from at least one of halogen, amino and hydroxyl groups; The heterocyclic group is selected from imidazole, pyrazol, carbazole, pyrrolidone, pyridinyl, piperidinyl, caprolactam, pyrazinyl, thiazolyl, purine, morpholino, and oxazolino.

5. The environmentally friendly semiconductive shielding material according to claim 4, wherein, The functional monomers are selected from aromatic olefin monomers, alkenyl-containing silane monomers, acrylate monomers, and optionally acrylic monomers; Preferably, the aromatic olefin monomer is selected from at least one of styrene, α-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, monosubstituted or polysubstituted styrene, monosubstituted or polysubstituted α-methylstyrene, monosubstituted or polysubstituted 1-vinylnaphthalene, and monosubstituted or polysubstituted 2-vinylnaphthalene; the substituted group is preferably selected from at least one of halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, C1-C8 straight-chain alkyl, C3-C8 branched alkyl or cycloalkyl, C1-C6 straight-chain alkoxy, C3-C8 branched alkoxy or cyclic alkoxy, C1-C8 straight-chain ester, C3-C8 branched ester or cyclic ester, C1-C8 straight-chain amino, and C3-C8 branched amino or cyclic amino; more preferably, the aromatic olefin monomer is selected from at least one of styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, and 4-methylstyrene; Preferably, the alkenyl-containing silane monomer is selected from at least one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriisopropoxysilane, vinyltritert-butoxysilane, vinyltriacetoxysilane, methylvinyldimethoxysilane, ethylvinyldiethoxysilane, allyltriethoxysilane, allyltrimethoxysilane, allyltriisopropoxysilane, vinyltris(β-methoxyethoxy)silane, allyltris(β-methoxyethoxy)silane, allyltritert-butoxysilane, allyltriacetoxysilane, methylallyldimethoxysilane, and ethylallyldiethoxysilane. Preferably, the acrylate monomer is selected from at least one of methyl methacrylate, sec-butyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, coconut oleate methacrylate, octadecyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminopropyl methacrylate, and glycidyl methacrylate; preferably, the acrylic monomer is selected from at least one of acrylic acid, methacrylic acid, and 2-ethylacrylic acid; more preferably, the molar ratio of the structural unit derived from the acrylate monomer to the structural unit derived from the acrylic monomer is 1:0-2, more preferably 1:0.125-1.

6. The environmentally friendly semiconductive shielding material according to claim 1, wherein, The first propylene polymer is an ethylene-propylene copolymer; preferably, the ethylene-propylene copolymer contains a propylene homopolymer or propylene random copolymer matrix component (1) and another propylene copolymer component (2) dispersed therein; more preferably, the ethylene-propylene copolymer has an island structure or a bicontinuous structure; even more preferably, the ethylene-propylene copolymer is prepared in situ in a reactor; Preferably, the ethylene-propylene copolymer has at least one of the following characteristics: a comonomer content of 8-25 wt%, preferably 10-22 wt%; a xylene-soluble content of 15-75 wt%, preferably 25-70 wt%; a melt flow rate of 0.01-15 g / 10 min at 230°C and 2.16 kg load, preferably 0.1-7 g / 10 min; a melt temperature Tm of 120-165°C, more preferably 125-150°C; a tensile strength of less than 20 MPa; and a xylene-soluble comonomer content of 10-50 wt%, preferably 15-35 wt%.

7. The environmentally friendly semiconductive shielding material according to claim 1, wherein, The second propylene polymer is a homopolymer or copolymer polypropylene, having at least one of the following characteristics: a comonomer content of 0-15 mol%, preferably 0-12 mol%, more preferably 0-8 mol%; a melt flow rate of 0.01-10 g / 10 min at 230°C and a load of 2.16 kg, preferably 0.1-5 g / 10 min; a melt temperature Tm of 110-180°C, more preferably 120-170°C; and a weight-average molecular weight of 20 × 10⁻⁶. 4 -50×10 4 g / mol; tensile strength greater than 20 MPa; Preferably, the comonomer of the copolymerized polypropylene is selected from at least one of C2-C8 α-olefins other than propylene; more preferably, the comonomer of the copolymerized polypropylene is selected from at least one of ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene; even more preferably, the comonomer of the copolymerized polypropylene is ethylene and / or 1-butene.

8. The environmentally friendly semiconductive shielding material according to claim 1, wherein, The conductive filler is selected from one or more of conductive carbon black, carbon nanotubes, graphene, and MXene, preferably conductive carbon black, and more preferably acetylene black; More preferably, the acetylene black has an oil absorption value of not less than 120cc / 100g, an iodine absorption value of not less than 70mg / g, and a residue of not more than 25ppm on a 325-mesh sieve.

9. A method for preparing the environmentally friendly semiconductive shielding material according to any one of claims 1-8, characterized in that, The preparation method includes the following steps: S1: Optionally, prepare a first propylene polymer grafted with a functional monomer by subjecting a reaction mixture including the first propylene polymer and the functional monomer to a grafting reaction in the presence of an inert gas to obtain the first propylene polymer grafted with a functional monomer. Optionally, a second propylene polymer modified by grafting functional monomers is prepared by subjecting a reaction mixture including the second propylene polymer and the functional monomers to a grafting reaction in the presence of an inert gas to obtain the second propylene polymer modified by grafting functional monomers. S2: Mix the materials containing a first propylene polymer grafted with functional monomers or unmodified, a second propylene polymer grafted with optional functional monomers, conductive fillers, and antioxidants, and melt-extrude and granulate to obtain the semi-conductive shielding material.

10. The method for preparing the environmentally friendly semiconductive shielding material according to claim 9, wherein, The reaction mixture contains a free radical initiator selected from peroxide free radical initiators and / or azo free radical initiators; the mass ratio of the free radical initiator to the functional monomer is 0.01-10:100, preferably 0.5-5:100; The peroxide-based free radical initiator is preferably selected from at least one of benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, dodecyl peroxide, tert-butyl peroxide, diisopropyl peroxide, tert-butyl peroxide, and dicyclohexyl peroxide.

11. The method for preparing the environmentally friendly semiconductive shielding material according to claim 9, wherein, The grafting reaction is carried out at a temperature of 30-130°C, preferably 60-120°C, for a time of 0.5-10 hours, preferably 1-6 hours. The temperature of melt extrusion is 170-250℃, preferably 180-230℃, and more preferably 190-220℃.

12. The application of the environmentally friendly semiconductive shielding material according to any one of claims 1-8 in the field of cable semiconductive shielding.

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