CN113571237B - A high-performance polypropylene cable - Google Patents

Abstract

The invention belongs to the electrical field and relates to a high-performance polypropylene cable. The cable comprises: at least one conductor and at least one electrical insulation layer surrounding the conductor; wherein, the material of the electrical insulation layer is at least one polypropylene graft containing anhydride groups; The polypropylene graft includes structural units derived from copolymerized polypropylene, structural units derived from anhydride monomers, and structural units derived from polymerized monomers containing ethylenic groups. The cable of the invention has a higher working temperature, and, under the condition of ensuring the same voltage level and insulation level, has the advantages of thinner electrical insulation layer, better heat dissipation and smaller weight.

Description

A high-performance polypropylene cable

technical field

The invention belongs to the electrical field, and in particular relates to a high-performance polypropylene cable.

Background technique

At present, cross-linked polyethylene is generally used as the insulating material for high-voltage DC cables at home and abroad. The working temperature is generally 70 ° C, and the long-term working design field strength is about 12kV/mm. At present, with the further improvement of the operating voltage and transmission capacity of high-voltage DC cables, The operating environment of cable insulation has also become more stringent due to the further increase of temperature and electric field strength, which puts forward higher requirements on the performance of cable insulation materials, that is, it still has higher performance under higher temperature and electric field strength conditions. Strong insulating properties. However, the operating temperature of traditional cross-linked polyethylene has reached its limit and cannot be further improved. Therefore, it is urgent to develop DC cables using new high-temperature and high-field insulating materials to meet the requirements of cable systems working under high-voltage and large-capacity conditions.

The current XLPE insulated DC cables are mostly manufactured using three-layer co-extruded extrusion insulation preparation methods. The extrusion process is mainly divided into three steps: heating and melting of insulating materials, cross-linking (vulcanization), and cooling and forming. Crosslinking initiators are generally used to make polyethylene molecules undergo crosslinking reactions, which makes the production process of cables more complicated, and the introduction of crosslinking initiators inevitably introduces crosslinking by-product impurities into the main insulation. This will have a certain negative impact on the insulation properties of the finished cable. In addition, cross-linked polyethylene is a thermosetting plastic that cannot be recycled, and its pyrolysis products are extremely harmful to the environment. Therefore, in order to simplify the cable production process, improve the final quality of cable insulation, and eliminate its possible harm to the environment, it is necessary to find a new thermoplastic recyclable cable insulation material and its preparation process to replace the traditional polyethylene material. And its cross-linking process realizes the manufacture and engineering application of low-cost, high-performance, recyclable insulated power cables.

Contents of the invention

The purpose of the invention is to overcome the problem that existing cable products cannot meet the requirements of stable operation under high temperature and high field strength, and provide a high-performance polypropylene cable. The cable uses a polypropylene graft containing anhydride groups as the main insulation layer, which can maintain or even have higher volume resistivity and stronger breakdown resistance than existing cables at higher operating temperatures Performance, while its mechanical properties can also meet the requirements of the cable.

The invention provides a high-performance polypropylene cable, which includes:

at least one conductor and at least one electrically insulating layer surrounding said conductor;

Wherein, the material of the electrical insulation layer is at least one polypropylene graft containing anhydride groups;

The polypropylene graft containing acid anhydride groups includes structural units derived from copolymerized polypropylene, structural units derived from acid anhydride monomers and structural units derived from vinyl-containing polymerized monomers; The weight of the propylene graft is based on the weight of the polypropylene graft containing the acid anhydride group, and the content of the structural unit derived from the acid anhydride monomer and the vinyl-containing polymer monomer and in the grafted state is 0.1 to 5 wt%, Preferably it is 0.4-3wt%; and, the content of structural units derived from acid anhydride monomers and in grafted state in the polypropylene graft containing acid anhydride groups is 0.05-2wt%, preferably 0.2-0.7wt% .

According to the invention, preferably, the anhydride is selected from anhydrides having at least one degree of olefinic unsaturation. More preferably, the acid anhydride is selected from maleic anhydride and/or itaconic anhydride. Further preferably, the acid anhydride is maleic anhydride.

According to a preferred embodiment of the present invention, the present invention provides a kind of high-performance polypropylene cable, and this cable comprises:

at least one conductor and at least one electrically insulating layer surrounding said conductor;

Wherein, the material of the electrical insulation layer is at least one polypropylene graft containing anhydride groups;

The polypropylene grafts containing acid anhydride groups include structural units derived from copolymerized polypropylene, structural units derived from maleic anhydride monomers and structural units derived from vinyl-containing polymerized monomers; to contain acid anhydride groups The weight of the polypropylene graft is based on the weight of the polypropylene graft containing the anhydride group, and the content of the structural unit derived from the maleic anhydride monomer and the vinyl-containing polymer monomer and in the grafted state is 0.1 ~5wt%, preferably 0.4~3wt%; and, the content of structural units derived from maleic anhydride monomers and in grafted state in the polypropylene graft containing anhydride groups is 0.05~2wt%, preferably 0.2 to 0.7 wt%.

The core of the present invention is to adopt a kind of new material as the electric insulating layer of cable, therefore, the present invention has no special limitation to the form of cable and concrete structure, can adopt various cable forms (direct current or alternating current, single core or Multi-core) and the corresponding structures. In the cable of the present invention, except that the electrical insulating layer adopts a new type of grafted modified polypropylene material, other layer structures and other layer materials can be conventionally selected in the field.

The cable of the present invention may be a DC cable or an AC cable; preferably a DC cable; more preferably, the cable is a medium-high voltage DC cable or an extra-high voltage DC cable. In the present invention, low voltage (LV) means a voltage lower than 1kV, medium voltage (MV) means a voltage in the range of 1kV to 40kV, high voltage (HV) means a voltage higher than 40kV, preferably higher than 50kV, and extra high voltage (EHV) ) means a voltage of at least 230kV.

According to a preferred embodiment of the present invention, the cable has at least one cable core, and each of the cable cores sequentially includes: a conductor, an optional conductor shielding layer, an electrical insulation layer, and an optional electrical insulation shielding layer from the inside to the outside. layer, optional metal shielding layer. Wherein, the conductor shielding layer, the electric insulation shielding layer and the metal shielding layer can be set as required, and are generally used in cables above 6kV.

In addition to the structures described above, the cable may also include armor and/or jacket layers.

The cable of the present invention may be a single-core cable or a multi-core cable, and for a multi-core cable, the cable may further include a filling layer and/or a tape layer. The filling layer is formed by filling material filled between the wire cores. The tape layer covers the outside of all wire cores to ensure that the wire cores and filling layers are circular, prevent the wire cores from being scratched by the armor, and play a role of flame retardancy.

In the cable of the present invention, said conductor is a conductive element usually made of metallic material, preferably aluminum, copper or other alloys, comprising one or more metallic wires. The DC resistance and the number of single wires of the conductor must meet the requirements of GB/T 3956. The preferred conductor is a tightly stranded circular structure with a nominal cross-sectional area of 800mm ² or less; or a split conductor structure with a nominal cross-sectional area of 1000mm ² or greater and the number of conductors is not less than 170.

In the cable of the present invention, the conductor shielding layer may be a covering layer made of materials such as polypropylene, polyolefin elastomer, and carbon black, and the volume resistivity at 23°C is less than 1.0Ω·m, and the volume resistivity at 90°C is Resistivity <3.5Ω·m, melt flow rate at 230°C under 2.16kg load is usually 0.01-30g/10min, preferably 0.05-20g/10min, more preferably 0.1-10g/10min, more preferably 0.2 ~8g/10min; tensile strength ≥12.5MPa; elongation at break ≥150%. The thickness of the thinnest point of the conductor shielding layer is not less than 0.5mm, and the average thickness is not less than 1.0mm.

In the cable of the present invention, the material of the electrical insulating layer is at least one polypropylene graft containing an acid anhydride group, which means that the base material constituting the electrical insulating layer is the polypropylene graft containing an acid anhydride group, In addition to the polypropylene grafts containing anhydride groups, further components such as polymer components or additives may be included, preferably additives such as antioxidants, stabilizers, processing aids, flame retardants, water tree retarders Any one or more of hysteresis additives, acid or ion scavengers, inorganic fillers, voltage stabilizers and anticopper agents. The types and amounts of additives are conventional and known to those skilled in the art.

The preparation method of the electrical insulation layer of the present invention can also adopt the conventional method in the field of cable preparation, for example, the polypropylene graft containing anhydride group is mixed with optional various additives, pelletized with a twin-screw extruder, The resulting pellets are then extruded through an extruder to produce an electrical insulating layer. Generally, the conductor shielding material can be co-extruded with polypropylene graft pellets containing acid anhydride groups to form a structure of conductor shielding layer + electrical insulation layer, or to form a conductor shielding layer + electrical insulation layer + electrical insulation shielding layer Structure. For specific operations, conventional methods and process conditions in this field can be used.

Due to the use of the polypropylene graft containing acid anhydride groups, the thickness of the electrical insulation layer in the present invention can only be 50% to 95% of the nominal thickness value of the XLPE insulation layer in GB/T 12706. The thickness of the insulating layer is 70% to 90% of the nominal thickness of the XLPE insulating layer in GB/T12706; the eccentricity is not more than 10%.

In the cable of the present invention, the electrical insulating shielding layer may be a covering layer made of materials such as polypropylene, polyolefin elastomer, and carbon black, and the volume resistivity at 23°C is less than 1.0Ω·m, and the volume resistivity at 90°C is Volume resistivity <3.5Ω·m. At 230°C, the melt flow rate under a load of 2.16kg is 0.01-30g/10min, preferably 0.05-20g/10min, more preferably 0.1-10g/10min, more preferably 0.2-8g/10min; tensile strength≥ 12.5MPa; elongation at break ≥ 150%. The thickness of the thinnest point of the electrical insulation shielding layer is not less than 0.5mm, and the average thickness is not less than 1.0mm.

In the cable of the present invention, the metal shielding layer may be a copper tape shielding layer or a copper wire shielding layer.

In the cable of the present invention, the filling layer may be a polymer material, such as PE/PP/PVC or recycled rubber material.

In the cable of the present invention, the cladding layer/armouring layer is usually made of copper wire metal cage, lead or aluminum metal sheath, etc., and wraps the metal covering layer on the outer surface of the electrical insulation shielding layer. Volume resistivity ≤1000Ω·m.

In the cable of the present invention, the material of the sheath layer can be any one of polyvinyl chloride, polyethylene or low-smoke halogen-free materials. The sheath layer includes both an inner sheath layer and an outer sheath layer.

Each layer structure above can be prepared by conventional methods in the art. For example, the conductor shielding layer, electrical insulation layer, and sheathing layer can be formed by extruding through an extruder, and the metal shielding layer and armor can be formed by wrapping.

In the polypropylene graft containing anhydride groups used in the present invention, the "structural unit" means that it is a part of the polypropylene graft containing anhydride groups, and its form is not limited. Specifically, "structural unit derived from copolymerized polypropylene" refers to a product formed from copolymerized polypropylene, which includes both "group" form and "polymer" form. "Structural unit derived from (maleic) anhydride monomer" refers to the product formed from (maleic) anhydride, which includes both "radical" form and "monomer" form, and also includes "polymer "Form. "Structural units derived from polymerized monomers containing ethylenic groups" means products formed from polymerized monomers containing ethylenic groups, which include both "radical" and "monomer" forms, and "polymers" "Form. The "structural unit" may be a repeating unit or a non-repeating independent unit.

In the present invention, the structural unit derived from the (maleic) anhydride monomer "in the grafted state" refers to the structural unit derived from the (maleic) anhydride monomer that forms a covalent connection (graft) with the copolymerized polypropylene . A structural unit derived from an ethylenic group-containing polymerizable monomer "in a grafted state" means a structural unit derived from an ethylenic group-containing polymerizable monomer that forms a covalent linkage (graft) to the copolymerized polypropylene.

In the present invention, the meaning of "comonomer" of copolymerized polypropylene is known to those skilled in the art, and refers to a monomer copolymerized with propylene.

According to the present invention, preferably, the polypropylene graft containing acid anhydride groups is prepared by grafting reaction of copolymerized polypropylene, (maleic) anhydride monomer and vinyl-containing polymerized monomer, preferably through solid phase grafting branch reaction. The grafting reaction in the present invention is a free radical polymerization reaction, therefore, the "in a grafted state" refers to a state in which a reactant forms a connection with another reactant after undergoing free radical polymerization. The connection includes both direct connection and indirect connection.

During the grafting reaction, the (maleic) anhydride monomer and the ethylenically polymerized monomer may polymerize individually or with each other to form a certain amount of ungrafted polymer. The term "polypropylene graft containing acid anhydride groups" of the present invention both includes the product (crude product) directly prepared by grafting reaction of polypropylene copolymer, (maleic) anhydride monomer and vinyl-containing polymerized monomer, It also includes the pure product of grafted modified polypropylene obtained by further purification of the product.

According to the present invention, the polypropylene graft containing acid anhydride groups as the material of the electrical insulation layer preferably has at least one of the following characteristics: at 230°C, the melt flow rate under a load of 2.16kg is 0.01- 30g/10min, preferably 0.05-20g/10min, more preferably 0.1-10g/10min, more preferably 0.2-5g/10min; flexural modulus 20-900MPa, more preferably 50-600MPa; elongation at break≥ 200%, preferably elongation at break ≥ 300%. Preferably, the tensile strength of the polypropylene graft containing anhydride groups is greater than 5 MPa, preferably 10-40 MPa.

In addition, in terms of electrical properties, the polypropylene graft containing anhydride groups has at least one of the following characteristics:

- The working temperature of the polypropylene graft containing anhydride groups is ≥90°C, preferably 90-160°C;

- The breakdown field strength Eg of the polypropylene graft containing acid anhydride groups at 90°C is ≥ 210kV/mm, preferably 210-800kV/mm;

- The difference ΔE between the breakdown field strength E _g of the polypropylene graft containing acid anhydride groups at 90°C and the breakdown field strength E of the copolymerized polypropylene at 90°C divided by the copolymerization The breakdown field strength change rate ΔE/E obtained from the breakdown field strength E of polypropylene at 90°C is greater than 1.8%, preferably 2% to 50%, more preferably 5% to 35%, and even more preferably 8%. ~28%;

- DC volume resistivity ρ _vg ≥ 1.5×10 ¹³ Ω·m, preferably 1.5×10 ¹³ Ω·m～1.0, of the polypropylene graft containing acid anhydride groups at 90°C and 15 kV/mm field strength ×10 ²⁰ Ω·m;

-The DC volume resistivity _ρvg of the polypropylene graft containing acid anhydride groups at 90°C and a field strength of 15kV/mm and the DC volume resistance of the copolymerized polypropylene at 90°C and a field strength of 15kV/mm The ratio ρvg _{/ ρv} of the rate _ρv is greater than 2, preferably 2.1-40, more preferably 2.3-20, and even more preferably 2.5-10;

- The dielectric constant of the polypropylene graft containing acid anhydride groups at 90°C and 50 Hz is greater than 2.0, preferably 2.1-2.5.

According to the present invention, the copolymerized polypropylene (base polypropylene in the present invention) is a propylene copolymer containing ethylene or higher alpha-olefins or a mixture thereof. Specifically, the comonomer of the copolymerized polypropylene is at least one selected from C ₂ -C ₈ α-olefins other than propylene. The C ₂ -C ₈ α-olefins other than propylene include but are not limited to: ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene At least one of ene and 1-octene, preferably ethylene and/or 1-butene, and more preferably, the copolymerized polypropylene consists of propylene and ethylene.

According to the present invention, preferably, the molar ratio of the structural units derived from (maleic) anhydride monomers to the structural units derived from vinyl-containing polymerized monomers in the polypropylene graft containing anhydride groups is 1: 1-20, preferably 1:1-10.

The copolymerized polypropylene of the present invention may be a heterophasic propylene copolymer. The heterophasic propylene copolymer may contain a propylene homopolymer or propylene random copolymer matrix component (1 ), and dispersed therein another propylene copolymer component (2). In propylene random copolymers, the comonomers are randomly distributed on the main chain of the propylene polymer. Preferably the copolymerized polypropylene of the present invention is a heterophasic propylene copolymer produced in situ in the reactor by known processes.

According to a preferred embodiment, the heterophasic propylene copolymer comprises a propylene homopolymer matrix or a random copolymer matrix (1), and dispersed therein one or more ethylene or higher α-olefin comonomers bulk propylene copolymer component (2). The heterophasic propylene copolymer may be an islands-in-the-sea structure or a bicontinuous structure.

Two kinds of heterophasic propylene copolymers are known in the art, heterophasic propylene copolymers comprising propylene random copolymer as matrix phase or heterophasic propylene copolymers comprising propylene homopolymer as matrix phase. The random copolymer matrix (1) is a copolymer formed by randomly distributing comonomer moieties on the polymer chain, in other words, consisting of alternating sequences of two monomer units of random length (including single molecules). Preferably the comonomer in the matrix (1) is selected from ethylene or butene. It is particularly preferred that the comonomer in the matrix (1) is ethylene.

Preferably the propylene copolymer (2) dispersed in the homopolymer or copolymer matrix (1) of the heterophasic propylene copolymer is substantially amorphous. The term "substantially amorphous" here means that the propylene copolymer (2) has a lower degree of crystallinity than the homopolymer or copolymer matrix (1).

According to the present invention, in addition to the above-mentioned compositional features, the copolymerized polypropylene has at least one of the following features: the comonomer content is 0.5-40 mol%, preferably 0.5-30 mol%, preferably 4-25 wt%, more preferably 4-22wt%; xylene soluble content is 2-80wt%, preferably 18-75wt%, more preferably 30-70wt%, more preferably 30-67wt%; soluble comonomer content It is 10-70wt%, preferably 10-50wt%, more preferably 20-35wt%; the intrinsic viscosity ratio of soluble matter to polypropylene is 0.3-5, preferably 0.5-3, more preferably 0.8-1.3.

According to the present invention, preferably, the copolymerized polypropylene also has at least one of the following characteristics: a melt flow rate of 0.01-60 g/10 min, preferably 0.05-35 g/10 min at 230°C under a load of 2.16 kg, More preferably 0.5-15g/10min, more preferably 0.5-8g/10min; melting temperature Tm is above 100°C, preferably 110-180°C, more preferably 110-170°C, still more preferably 120-170°C, more preferably More preferably, it is 120-166 degreeC. The weight average molecular weight is preferably 20×10 ⁴ to 60×10 ⁴ g/mol. The base polypropylene with a high Tm has satisfactory impact strength and flexibility at both low and high temperatures. In addition, when the base polypropylene with a high Tm is used, the graft-modified polypropylene of the present invention has the ability to withstand higher Advantages of working temperature. The copolymerized polypropylene in the present invention is preferably a porous granular or powdery resin.

According to the present invention, preferably, the copolymerized polypropylene also has at least one of the following characteristics: flexural modulus is 10-1000 MPa, preferably 50-600 MPa; elongation at break ≥ 200%, preferably elongation at break ≥ 300%. Preferably, the tensile strength of the copolymerized polypropylene is greater than 5 MPa, preferably 10-40 MPa.

The copolymerized polypropylene of the present invention may include but not limited to NS06 of Sinopec Wuhan Petrochemical, SPF179 of Sinopec Qilu Petrochemical and other commercially available polypropylene powder suitable for the present invention, and may also be obtained through Chinese patents CN1081683, CN1108315, It is produced by the polymerization process recorded in CN1228096, CN1281380, CN1132865C and CN102020733A. Commonly used polymerization processes include Basell's Spheripol process, Mitsui Oil & Chemical's Hypol process, Borealis' Borstar PP process, DOW Chemical's Unipol process, and INEOS (formerly BP-Amoco) company's Innovene gas phase process.

The ethylenic group-containing polymerizable monomer described in the present invention is preferably selected from at least one of the monomers having the structure shown in Formula 1,

In Formula 1, R ₁ , R ₂ , R ₃ are each independently selected from H, substituted or unsubstituted alkyl; R ₄ is selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or Unsubstituted aryl, substituted or unsubstituted ester, substituted or unsubstituted carboxy, substituted or unsubstituted cycloalkyl or heterocyclic, cyano.

Preferably, R ₁ , R ₂ , R ₃ are each independently selected from H, substituted or unsubstituted C ₁ -C ₆ alkyl, more preferably, R ₁ , R ₂ , R ₃ are each independently selected from H, Substituted or unsubstituted C ₁ -C ₃ alkyl; preferably, R ₄ is selected from substituted or unsubstituted C ₁ -C ₂₀ alkyl, substituted or unsubstituted C ₁ -C ₂₀ alkoxy, substituted or unsubstituted Substituted C ₆ -C ₂₀ aryl, substituted or unsubstituted C ₁ -C ₂₀ ester, substituted or unsubstituted C ₁ -C ₂₀ carboxyl, substituted or unsubstituted C ₃ -C ₂₀ cycloalkyl or hetero Cyclic group, cyano group, the substituted group is halogen, hydroxyl, amino, C ₁ -C ₆ alkyl, C ₃ -C ₆ cycloalkyl; further preferably, R ₄ is selected from substituted or unsubstituted C ₁ -C ₁₂ alkyl, substituted or unsubstituted C ₁ -C ₁₈ alkoxy, substituted or unsubstituted C ₆ -C ₁₂ aryl, substituted or unsubstituted C ₁ -C ₁₂ ester, substituted or unsubstituted Substituted C ₁ -C ₁₂ carboxyl, substituted or unsubstituted C ₃ -C ₁₂ cycloalkyl or heterocyclic group, cyano, the substituted group is halogen, C ₁ -C ₆ alkyl, C ₃ - C ₆ cycloalkyl; more preferably, R ₄ is selected from substituted or unsubstituted C ₁ -C ₆ alkyl, substituted or unsubstituted C ₁ -C ₁₂ alkoxy, substituted or unsubstituted C ₆ -C ₈ Aryl, substituted or unsubstituted C ₁ -C ₆ ester group, substituted or unsubstituted C ₁ -C ₆ carboxyl group, substituted or unsubstituted C ₃ -C ₆ cycloalkyl or heterocyclic group, cyano group. Specifically preferably, the heterocyclic group is selected from imidazolyl, pyrazolyl, carbazolyl, pyrrolidinyl, pyridyl, piperidinyl, caprolactam, pyrazinyl, thiazolyl, purinyl, morpholinyl, oxa Azolinyl.

More preferably, each of R ₁ , R ₂ , and R ₃ is independently selected from H, substituted or unsubstituted C ₁ -C ₆ alkyl;

R ₄ is 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 combination of the group shown in formula 5 and the group shown in formula 6, heterocycle group;

In Formula 2, R ⁴ -R ⁸ are each independently selected from H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, substituted or unsubstituted C ₁ -C ₁₂ alkyl, substituted or unsubstituted C ₃ -C ₁₂ cycloalkyl group, substituted or unsubstituted C ₁ -C ₁₂ alkoxy group, substituted or unsubstituted C ₁ -C ₁₂ ester group, substituted or unsubstituted C ₁ -C ₁₂ amino group , the substituted group is selected from halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, C ₁ -C ₁₂ alkyl, C ₃ -C ₁₂ cycloalkyl, C ₁ -C ₁₂ alkoxy , C ₁ -C ₁₂ ester group, C ₁ -C ₁₂ amine group; preferably, R ⁴ -R ⁸ are each independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C ₁ -C ₆ Alkyl, substituted or unsubstituted C ₁ -C ₆ alkoxy;

In Formula 3, R ₄ -R ₁₀ are each independently selected from H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, substituted or unsubstituted C ₁ -C ₁₂ alkyl, substituted or unsubstituted C ₃ -C ₁₂ cycloalkyl group, substituted or unsubstituted C ₁ -C ₁₂ alkoxy group, substituted or unsubstituted C ₁ -C ₁₂ ester group, substituted or unsubstituted C ₁ -C ₁₂ amino group , the substituted group is selected from halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, C ₁ -C ₁₂ alkyl, C ₃ -C ₁₂ cycloalkyl, C ₁ -C ₁₂ alkoxy , C ₁ -C ₁₂ ester group, C ₁ -C ₁₂ amine group; preferably, R ₄ -R ₁₀ are each independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C ₁ -C ₆ Alkyl, substituted or unsubstituted C ₁ -C ₆ alkoxy, the substituted group is selected from halogen, hydroxyl, amino, C ₁ -C ₆ alkyl, C ₁ -C ₆ alkoxy base;

In Formula 4, R ₄ '-R ₁₀ ' are each independently selected from H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, substituted or unsubstituted C ₁ -C ₁₂ alkyl, substituted or unsubstituted C ₃ -C ₁₂ cycloalkyl, substituted or unsubstituted C ₁ -C ₁₂ alkoxy, substituted or unsubstituted C ₁ -C ₁₂ ester, substituted or unsubstituted C ₁ -C ₁₂ Amino group, the substituted group is selected from halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, C ₁ -C ₁₂ alkyl, C ₃ -C ₁₂ cycloalkyl, C ₁ -C ₁₂ alkane Oxygen, C ₁ -C ₁₂ ester group, C ₁ -C ₁₂ amine group; preferably, R ₄ '-R ₁₀ ' are each independently selected from H, halogen, hydroxyl, amino, substituted or unsubstituted C ₁ -C ₆ alkyl, substituted or unsubstituted C ₁ -C ₆ alkoxy, the substituted group is selected from halogen, hydroxyl, amino, C ₁ -C ₆ alkyl, C ₁ -C ₆ alkoxy groups;

In formula 5, R _m is selected from the following substituted or unsubstituted groups: C ₁ -C ₂₀ straight chain alkyl, C ₃ -C ₂₀ branched chain alkyl, C ₃ -C ₁₂ cycloalkyl, C ₃ -C ₁₂ epoxyalkyl groups, C ₃ -C ₁₂ epoxyalkylene alkyl groups, the substituted groups are at least one selected from halogen, amino and hydroxyl groups.

Further preferably, the alkenyl-containing polymerizable monomer is selected from vinyl acetate, styrene, α-methylstyrene, (meth)acrylate, vinyl alkyl ether, vinylpyrrolidone, vinylpyridine, ethylene At least one of imidazole and acrylonitrile; the (meth)acrylate is preferably at least one of methyl (meth)acrylate, ethyl (meth)acrylate and glycidyl (meth)acrylate . Preferably, the vinylic group-containing polymerizable monomer is selected from vinyl acetate, styrene, α-methylstyrene. Further preferably, the ethylenic group-containing polymerizable monomer is styrene.

The polypropylene graft containing anhydride groups of the present invention can be prepared by a method comprising the following steps: in the presence of an inert gas, making The reaction mixture of the body is subjected to a grafting reaction to obtain the polypropylene graft containing an anhydride group.

The grafting reaction of the present invention can be carried out with reference to various conventional methods in the art, preferably a solid-phase grafting reaction. For example, in the presence of grafting (maleic) acid anhydride and vinyl-containing monomers, active grafting points are formed on copolymerized polypropylene, or active grafting points are first formed on copolymerized polypropylene and then used for grafting. body is processed. Grafting sites can be formed by treatment with free radical initiators, or by high energy ionizing radiation or microwave treatment. Free radicals generated in the polymer as a result of chemical or radiation treatment form graft sites on the polymer and initiate monomer polymerization at these sites.

Preferably, the grafting site is initiated by a free radical initiator and the grafting reaction is further carried out. In this case, the reaction mixture further includes a free radical initiator; further preferably, the free radical initiator is selected from peroxide-based free-radical initiators and/or azo-based free-radical initiators.

Wherein, the peroxide free radical initiator is preferably selected from dibenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, lauryl peroxide, peroxide At least one of tert-butyl benzoate, diisopropyl peroxydicarbonate, tert-butyl peroxide (2-ethylhexanoate) and dicyclohexyl peroxydicarbonate; the azos are free The base initiator is preferably azobisisobutyronitrile and/or azobisisoheptanonitrile.

More preferably, the grafting point is initiated by a peroxide-based radical initiator and the grafting reaction is further performed.

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

Under the premise of satisfying the above-mentioned product characteristics, the present invention has no special limitation to the consumption of each component in the grafting reaction, specifically, the quality of the free radical initiator and the described (maleic) anhydride monomer and the described The ratio of the total mass of the alkenyl group-containing polymerizable monomers is 0.1-10:100, preferably 0.5-5:100. The mass ratio of the total mass of the (maleic) anhydride monomer and the vinyl-containing polymerized monomer to the copolymerized polypropylene is 0.1-8:100, preferably 0.3-5:100. The mass usage amount of the (maleic) anhydride monomer may be 5-100 wt%, preferably 10-100 wt%, of the mass usage amount of the ethylenic group-containing polymerizable monomer.

The present invention has no special limitation on the process conditions of the grafting reaction. Specifically, the temperature of the grafting reaction can be 30-130°C, preferably 60-120°C; the time can be 0.5-10h, preferably 1- 5h.

In the present invention, the "reaction mixture" includes all the materials added to the grafting reaction system, and the materials can be added at one time or in different stages of the reaction.

A dispersant may also be included in the reaction mixture of the present invention, and the dispersant is preferably water or an aqueous solution of sodium chloride. The mass dosage of the dispersant is preferably 50-300% of the mass of the copolymerized polypropylene.

In the reaction mixture of the present invention, an interface agent may also be included, and the interface agent is an organic solvent having a swelling effect on polyolefin, preferably at least one of the following organic solvents having a swelling effect on copolymerized polypropylene: ether solvent , ketone solvents, aromatic hydrocarbon solvents, alkane solvents; more preferably at least one of the following organic solvents: chlorinated benzene, polychlorinated benzene, alkane or cycloalkane above C ₆ , benzene, C ₁ -C ₄ alkyl substituted benzene, C ₂ -C ₆ aliphatic ether, C ₃ -C ₆ aliphatic ketone, decahydronaphthalene; more preferably at least one of the following organic solvents: benzene, toluene, xylene, chlorobenzene, tetrahydrofuran , ether, acetone, hexane, cyclohexane, decahydronaphthalene, heptane. The mass content of the interface agent is preferably 1-30% of the mass of the copolymerized polypropylene, more preferably 10-25%.

The reaction mixture of the present invention may also include an organic solvent as a solvent for dissolving the solid free radical initiator, the organic solvent preferably comprising C ₂ -C ₅ alcohols, C ₂ -C ₄ ethers and C ₃ -C ₅ ketones At least one of C ₂ -C ₄ alcohols, C ₂ -C ₃ ethers and C ₃ -C ₅ ketones, more preferably at least one of ethanol, ether and acetone A sort of. The mass content of the organic solvent is preferably 1-35% of the mass of the copolymerized polypropylene.

In the preparation method of the polypropylene graft containing acid anhydride groups of the present invention, the limitations on the polymeric monomers containing ethylenic groups, acid anhydrides and copolymerized polypropylene are the same as those described above, and will not be repeated here.

According to the present invention, the preparation method of the polypropylene graft containing anhydride groups can be selected from one of the following methods:

Mode 1, the preparation method includes the following steps:

a. Place the copolymerized polypropylene in a closed reactor for inert gas replacement;

b. adding the free radical initiator, the acid anhydride monomer and the vinyl-containing polymerized monomer into the closed reactor, stirring and mixing;

c. Optionally add an interface agent, and optionally make the reaction system swell;

d. Optionally add a dispersant to heat up the reaction system to the grafting reaction temperature to carry out the grafting reaction;

e. After the reaction is finished, optionally filter (in the case of using a water phase dispersant) and dry to obtain the polypropylene graft containing an acid anhydride group.

More specifically, the preparation method includes the following steps:

a. Place the copolymerized polypropylene in a closed reactor for inert gas replacement;

b. Dissolving the free radical initiator in the anhydride monomer and the vinyl-containing polymerized monomer is prepared into a solution, added to a closed reactor equipped with polypropylene copolymer, and stirred and mixed;

c. Add 0-30 parts of interface agent, and optionally make the reaction system swell at 20-60°C for 0-24 hours;

d. Add 0-300 parts of dispersant, raise the temperature of the system to the graft polymerization temperature of 30-130°C, and react for 0.5-10 hours;

e. After the reaction is finished, optionally filter (in the case of using a water phase dispersant) and dry to obtain the polypropylene graft containing an acid anhydride group.

Mode 2, the preparation method includes the following steps:

a. Place the copolymerized polypropylene in a closed reactor for inert gas replacement;

B. organic solvent and free radical initiator are mixed, join in described airtight reactor;

c. removing said organic solvent;

d. adding acid anhydride monomers and vinyl-containing polymer monomers, optionally adding interface agents, and optionally allowing the reaction system to swell;

e. Optionally add a dispersant to heat up the reaction system to the grafting reaction temperature to carry out the grafting reaction;

f. After the reaction is finished, optionally filter (in the case of using a water phase dispersant) and dry to obtain the polypropylene graft containing an acid anhydride group.

More specifically, the preparation method includes the following steps:

a. Place the copolymerized polypropylene in a closed reactor for inert gas replacement;

b. the organic solvent and the free radical initiator are mixed, and a solution is added to a closed reactor equipped with polypropylene copolymer;

c. Inert gas purging or removal of said organic solvent by vacuum;

d. Add acid anhydride monomers and ethylenic group-containing polymerizable monomers, add 0-30 parts of interface agent, and optionally make the reaction system swell at 20-60°C for 0-24 hours;

e. Add 0-300 parts of dispersant, raise the temperature of the system to the graft polymerization temperature of 30-130°C, and react for 0.5-10 hours;

f. After the reaction is finished, optionally filter (in the case of using a water phase dispersant) and dry to obtain the polypropylene graft containing an acid anhydride group.

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

As mentioned above, the "polypropylene grafts containing acid anhydride groups" of the present invention both include the products (crude products) directly prepared by grafting reaction of copolymerized polypropylene and acid anhydride monomers and vinyl-containing polymer monomers, as well as The pure product of graft-modified polypropylene obtained by further purification of the product is included. Therefore, the preparation method of the present invention may optionally include a step of purifying the crude product. The purification can adopt various conventional methods in the art, such as extraction.

The present invention has no special limitation on the grafting efficiency of the grafting reaction, but a higher grafting efficiency is more conducive to obtaining the polypropylene graft containing acid anhydride groups with desired properties through one-step grafting reaction. Therefore, it is preferable to control the grafting efficiency of the grafting reaction to be 20-100%, more preferably 25-80%. The concept of the grafting efficiency is well known to those skilled in the art, and refers to the total amount of acid anhydride monomers and vinyl-containing polymerized monomers on the graft/reaction feeding anhydride monomers and the total amount of vinyl-containing polymerized monomers .

The inert gas in the present invention can be various inert gases commonly used in the art, including but not limited to nitrogen and argon.

The cable of the present invention can be produced through various conventional preparation processes in the field, which is not particularly limited in the present invention.

According to a specific embodiment of the present invention, the preparation method of the cable is as follows:

Preparation of conductors: Perform compaction and stranding operations on multiple monofilament conductors (such as aluminum) to obtain the inner core of the conductor; Body core.

Preparation of polypropylene graft particles containing acid anhydride groups: mixing polypropylene grafts containing acid anhydride groups with optional additives, and pelletizing with a twin-screw extruder.

Preparation of conductor shielding layer and electrical insulation layer: Conductor shielding material and the above-mentioned polypropylene graft particles containing acid anhydride groups are co-extruded and coated by an extruder outside the conductor inner core to form a conductor shielding layer + an electrical insulation layer, Or form a conductor shielding layer+electrical insulation layer+electrical insulation shielding layer (outer shielding layer).

Preparation of the metal shielding layer: Wrap copper tape or copper wire outside the electrical insulation layer (electrical insulation shielding layer) to form a metal shielding layer.

Preparation of the inner sheath layer: the sheath layer pellets are extruded outside the metal shielding layer through an extruder to form the inner sheath layer.

Armoring preparation: Use galvanized steel/stainless steel/aluminum alloy to make steel wire or steel tape armor, and wrap the inner sheath by single-layer armor left-hand or double-layer armor with inner layer right-hand and outer layer left-hand On the layer, the steel wire or steel tape armor should be tight, so that the gap between adjacent steel wires/steel tapes is the smallest.

Preparation of the outer sheath layer: the sheath layer pellets are extruded through an extruder outside the armor to form an outer sheath layer.

Finally, the high-performance polypropylene cable is obtained.

Compared with the existing cables, the cables of the present invention can still maintain or even have higher volume resistivity and stronger breakdown resistance performance at higher operating temperatures, and meanwhile, its mechanical properties can also meet the requirements for use of cables. Under the condition of ensuring the same voltage level and insulation level, the electrical insulating layer made of the polypropylene graft containing acid anhydride groups has thinner thickness, better heat dissipation and smaller weight than the electrical insulating layer of conventional cables. advantage. Therefore, the cable has a wider range of applications.

Other features and advantages of the present invention will be described in detail in the detailed description that follows.

Description of drawings

Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

Fig. 1 is a schematic cross-sectional structure diagram of a cable in a specific embodiment of the present invention.

Explanation of reference signs

1-conductor; 2-conductor shielding layer; 3-electrical insulation layer; 4-electrical insulation shielding layer; 5-metal shielding layer; 6-inner sheath layer; 7-armoring; 8-outer sheath layer.

Detailed ways

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

In the following examples and comparative examples:

1. Determination of comonomer content in polypropylene copolymer:

Comonomer content 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. The calibration method based on the results obtained from the quantitative ¹³ C-NMR spectrum is performed according to conventional methods in the art.

2. Determination of xylene soluble content in copolymerized polypropylene, soluble comonomer content and intrinsic viscosity ratio of soluble matter/copolymerized polypropylene:

The test was carried out with the CRYST-EX instrument of Polymer Char Company. Use trichlorobenzene solvent, heat up to 150°C for dissolution, hold the temperature for 90 minutes, take samples for testing, then lower the temperature to 35°C, hold the temperature for 70 minutes, take samples for testing.

3. Determination of weight average molecular weight of copolymerized polypropylene:

Determination by high-temperature GPC, using PL-GPC 220 gel permeation chromatography of Polymer Laboratory Company, the sample is dissolved in 1,2,4-trichlorobenzene, the concentration is 1.0mg/ml. The test temperature is 150°C, and the solution flow rate is 1.0ml/min. The molecular weight of polystyrene was used as an internal reference to establish a standard curve, and the molecular weight and molecular weight distribution of the sample were calculated according to the outflow time.

4. Determination of melt flow rate MFR:

According to the method specified in GB/T 3682-2018, it was measured with CEAST company's 7026 melt indexer at 230°C and under a load of 2.16kg.

5. Determination of melting temperature Tm:

The melting process and crystallization process of the material were analyzed by differential scanning calorimetry. The specific operation is: under the protection of nitrogen, measure 5~10mg samples from 20°C to 200°C using a three-stage heating and cooling measurement method, and use the change of heat flow to reflect the melting and crystallization process of the material, so as to calculate the melting temperature Tm.

6. Determination of grafting efficiency GE, parameter M1 and parameter M2:

Put 2-4g of grafted product into a Soxhlet extractor, extract with ethyl acetate for 24 hours, remove unreacted monomer and its homopolymer, obtain pure grafted product, dry and weigh, and calculate parameters M1, M2 and grafting efficiency GE.

According to the method test described in the literature (Zhang Guangping, polypropylene solid-phase grafting maleic anhydride in the ribbon reactor, China Plastics, the 2nd phase of the 16th volume in February, 2002, 69-71) and calculate the content of maleic anhydride Mass content % _MAH .

Parameter M1 represents the content of structural units derived from maleic anhydride monomers and alkenyl-containing polymerized monomers and in grafted state in the polypropylene graft containing anhydride groups; parameter M2 represents the content of the grafted polypropylene containing anhydride groups The content of structural units derived from maleic anhydride monomer and in grafted state in the polypropylene graft. In the present invention, the calculation formulas of M1, M2 and GE are as follows:

In the above formula, w ₀ is the mass of PP matrix; w ₁ is the mass of grafted product before extraction; w ₂ is the mass of grafted product after extraction; w ₃ is the mass of maleic anhydride monomer and alkenyl-containing polymerized monomer The total mass of the body; % _MAH is the mass content of maleic anhydride.

7. Determination of DC volume resistivity:

Measure according to the method specified in GB/T 1410-2006.

8. Determination of breakdown field strength:

Measure according to the method specified in GB/T 1408-2006.

9. Determination of tensile strength:

Measure according to the method specified in GB/T 1040.2-2006.

10. Determination of flexural modulus:

Measure according to the method specified in GB/T 9341-2008.

11. Determination of elongation at break:

Measure according to the method specified in GB/T 1040-2006.

12. Determination of dielectric constant and dielectric loss factor:

Measure according to the method specified in GB/T 1409-2006.

13. Determination of the ratio of the main insulation conductivity (resistivity) of the cable:

Carry out the test according to the method specified in Appendix A of TICW 7.1-2012. The main insulation conductivity ratio is equal to the main insulation conductivity of the cable at 90°C divided by the main insulation conductivity of the cable at 30°C.

14. Cable insulation space charge injection test (determination of electric field distortion rate):

Carry out the cable insulation space charge injection test according to the method specified in Appendix B of TICW 7.1-2012.

15. DC withstand voltage test:

Under normal temperature, use 1.85 times negative polarity rated voltage to continuously pressurize the cable for 2 hours. If there is no breakdown and discharge phenomenon, it is passed, otherwise it is not passed.

16. Load cycle test:

The cable is heated to 90°C at the rated temperature, and 1.85 times the rated voltage is applied for 8 hours, then naturally cooled and the voltage is removed for 16 hours, and the cycle is 12 days. If no breakdown occurs, it is passed.

The starting materials used in the examples are described in Table A below.

Table A

*Copolymerized polypropylene 1: The copolymerized polypropylene used in Example 1.

*Copolymerized polypropylene 2: The copolymerized polypropylene used in Example 2.

*Copolymerized polypropylene 3: The copolymerized polypropylene used in Example 3.

*Copolymerized polypropylene 4: The copolymerized polypropylene used in Example 4.

Example 1

Select the basic copolymerized polypropylene powder with the following characteristics: comonomer ethylene content 18.1wt%, xylene soluble matter content 48.7wt%, soluble comonomer content 31.9wt%, soluble matter/copolymerized polypropylene The intrinsic viscosity ratio is 0.89, the weight average molecular weight is 34.3×10 ⁴ g/mol, the MFR is 1.21g/10min at 230°C under a load of 2.16kg, Tm=143.4°C, and the breakdown field strength (90°C) is 236kV/ mm, the DC volume resistivity (90°C, 15kV/mm) is 1.16E13Ω·m, and the fine powder smaller than 40 mesh is removed by sieving. Weigh 2.0kg of the above-mentioned basic copolymerized polypropylene powder, add it into a 10L reaction kettle with mechanical stirring, seal the reaction system, and replace oxygen with nitrogen. Add a solution of 1.3g of dibenzoyl peroxide, 10g of maleic anhydride and 40g of styrene, stir and mix for 30min, swell at 40°C for 2 hours, heat up to 90°C, and react for 4 hours. After the reaction, the temperature was purged with nitrogen to obtain the polypropylene-g-styrene/maleic anhydride material product C1.

The various performance parameters of the obtained product were tested, and the results are shown in Table 1.

Example 2

Select the basic copolymerized polypropylene powder with the following characteristics: comonomer ethylene content 14.7wt%, xylene soluble matter content 41.7wt%, soluble comonomer content 34.5wt%, soluble matter/copolymerized polypropylene The intrinsic viscosity ratio is 0.91, the weight average molecular weight is 36.6×10 ⁴ g/mol, the MFR is 1.54g/10min at 230°C under a load of 2.16kg, Tm=164.9°C, and the breakdown field strength (90°C) is 248kV/ mm, the DC volume resistivity (90°C, 15kV/mm) is 7.25E12Ω·m, and the fine powder smaller than 40 mesh is removed by sieving. Weigh 2.0kg of the above-mentioned basic copolymerized polypropylene powder, add it into a 10L reaction kettle with mechanical stirring, seal the reaction system, and replace oxygen with nitrogen. Add a solution of 0.6g dibenzoyl peroxide, 5g maleic anhydride and 22g styrene, stir and mix for 30min, swell at 40°C for 3 hours, raise the temperature to 95°C, and react for 4 hours. After the reaction was completed, nitrogen was purged to lower the temperature to obtain the polypropylene-g-styrene/maleic anhydride material product C2.

The various performance parameters of the obtained product were tested, and the results are shown in Table 1.

Example 3

Select the basic copolymerized polypropylene powder with the following characteristics: comonomer ethylene content 20.1wt%, xylene soluble matter content 66.1wt%, soluble comonomer content 29.5wt%, soluble matter/copolymerized polypropylene The intrinsic viscosity ratio is 1.23, the weight average molecular weight is 53.8×10 ⁴ g/mol, the MFR is 0.51g/10min at 230°C under a load of 2.16kg, Tm=142.5°C, and the breakdown field strength (90°C) is 176kV/ mm, DC volume resistivity (90°C, 15kV/mm) is 5.63E12Ω·m, sieved to remove fine powder less than 40 mesh. Weigh 2.0kg of the above-mentioned basic copolymerized polypropylene powder, add it into a 10L reaction kettle with mechanical stirring, seal the reaction system, and replace oxygen with nitrogen. Add a solution of 2.6g of dibenzoyl peroxide, 12g of maleic anhydride and 88g of styrene, stir and mix for 30min, swell at 40°C for 2 hours, heat up to 90°C, and react for 4 hours. After the reaction was completed, nitrogen was purged to lower the temperature to obtain polypropylene-g-styrene/maleic anhydride material product C3.

The various performance parameters of the obtained product were tested, and the results are shown in Table 1.

Example 4

Select the basic copolymerized polypropylene powder with the following characteristics: comonomer ethylene content 4.8wt%, xylene soluble content 19.2wt%, soluble comonomer content 17.6wt%, soluble/copolymerized polypropylene The intrinsic viscosity ratio is 1.04, the weight average molecular weight is 29.2×10 ⁴ g/mol, the MFR is 5.37g/10min at 230°C under a load of 2.16kg, Tm=163.3°C, and the breakdown field strength (90°C) is 322kV/ mm, the DC volume resistivity (90°C, 15kV/mm) is 1.36E13Ω·m, and the fine powder smaller than 40 mesh is removed by sieving. Weigh 2.0kg of the above-mentioned basic copolymerized polypropylene powder, add it into a 10L reaction kettle with mechanical stirring, seal the reaction system, and replace oxygen with nitrogen. Add a solution of 0.6g dibenzoyl peroxide, 10g maleic anhydride, 11g styrene and 50g toluene, stir and mix for 30min, swell at 50°C for 2h, heat up to 100°C, and react for 1 hour. After the reaction was completed, nitrogen was purged to lower the temperature to obtain the polypropylene-g-styrene/maleic anhydride material product C4.

The various performance parameters of the obtained product were tested, and the results are shown in Table 1.

Example 5

Weigh 2.0kg of the basic copolymerized polypropylene powder in Example 1, add it into a 10L reactor with mechanical stirring, close the reaction system, and replace oxygen with nitrogen. Add a solution of 4.0g of dibenzoyl peroxide, 30g of maleic anhydride and 120g of styrene, stir and mix for 30min, swell at 40°C for 2 hours, heat up to 90°C, and react for 4 hours. After the reaction was completed, nitrogen was purged to lower the temperature to obtain the polypropylene-g-styrene/maleic anhydride product C5.

The various performance parameters of the obtained product were tested, and the results are shown in Table 1.

Comparative example 1

Weigh 2.0kg of T30S powder (breakdown field strength (90°C) of 347kV/mm, DC volume resistivity (90°C, 15kV/mm) of 1.18E13Ω m) that has been sieved to remove fine powder less than 40 meshes, and add In a 10L reaction kettle with mechanical stirring, the reaction system is closed, and oxygen is replaced by nitrogen. Add a solution of 1.3g of dibenzoyl peroxide, 10g of maleic anhydride and 40g of styrene, stir and mix for 60min, swell at 40°C for 2 hours, raise the temperature to 90°C, and react for 4 hours. After the reaction, the nitrogen gas was purged to lower the temperature to obtain the polypropylene-g-styrene/maleic anhydride material product D1.

The various performance parameters of the obtained product were tested, and the results are shown in Table 1.

Comparative example 2

Select the basic copolymerized polypropylene powder with the following characteristics: comonomer ethylene content 18.1wt%, xylene soluble matter content 48.7wt%, soluble comonomer content 31.9wt%, soluble matter/copolymerized polypropylene The intrinsic viscosity ratio is 0.89, the weight average molecular weight is 34.3×10 ⁴ g/mol, the MFR is 1.21g/10min at 230°C under a load of 2.16kg, Tm=143.4°C, and the breakdown field strength (90°C) is 236kV/ mm, the DC volume resistivity (90°C, 15kV/mm) is 1.16E13Ω·m, and the fine powder smaller than 40 mesh is removed by sieving. Weigh 2.0kg of the above-mentioned basic copolymerized polypropylene powder, add it into a 10L reaction kettle with mechanical stirring, seal the reaction system, and replace oxygen with nitrogen. Add a solution of 5g dibenzoyl peroxide, 40g maleic anhydride and 160g styrene, stir and mix for 60min, swell at 40°C for 2 hours, heat up to 90°C, and react for 4 hours. After the reaction, the nitrogen gas was purged to lower the temperature to obtain the polypropylene-g-styrene/maleic anhydride material product D2.

The various performance parameters of the obtained product were tested, and the results are shown in Table 1.

Comparative example 3

Select the basic copolymerized polypropylene powder with the following characteristics: comonomer ethylene content 18.1wt%, xylene soluble matter content 48.7wt%, soluble comonomer content 31.9wt%, soluble matter/copolymerized polypropylene The intrinsic viscosity ratio is 0.89, the weight average molecular weight is 34.3×10 ⁴ g/mol, the MFR is 1.21g/10min at 230°C under a load of 2.16kg, Tm=143.4°C, and the breakdown field strength (90°C) is 236kV/ mm, the DC volume resistivity (90°C, 15kV/mm) is 1.16E13Ω·m, and the fine powder smaller than 40 mesh is removed by sieving. Weighed 2000 g of the above-mentioned basic copolymerized polypropylene powder, mixed with 50 g of styrene/maleic anhydride copolymer, and mixed with a screw extruder to obtain blend D3.

The various performance parameters of the obtained product were tested, and the results are shown in Table 1.

Comparing the data of Example 1 and Comparative Example 1, it can be seen that adopting T30S powder as the base powder, the flexural modulus of the gained polypropylene-g-styrene/maleic anhydride material is too high, and the mechanical properties of the material are poor, which cannot satisfy Insulation material processing needs.

Comparing the data of Example 1 and Comparative Example 2, it can be seen that the addition of maleic anhydride monomer/olefin-containing polymerized monomer is too high (M1 value is too high) and will lead to the obtained polypropylene-g-styrene/maleic anhydride The breakdown field strength and volume resistivity of the acid anhydride material decrease, which affects the electrical properties of the product.

Comparing the data of Example 1 and Comparative Example 3, it can be seen that the method of blending styrene/maleic anhydride copolymer leads to a significant decrease in the breakdown field strength and volume resistivity of the material, which greatly affects the electrical properties of the material.

In summary, it can be seen from the data in Table 1 that the sharp decline in flexural modulus makes the polypropylene grafts containing anhydride groups of the present invention have good mechanical properties, and compared with ungrafted maleic anhydride/olefin-containing The breakdown field strength of the grafted product can be improved for the copolymerized polypropylene based polymerized monomer, which shows that the polypropylene grafted product containing acid anhydride group of the present invention has good electrical properties at the same time.

In addition, it can be seen from the dielectric constant and dielectric loss data that the graft modification does not affect the dielectric constant and dielectric loss of the material, and the material of the invention meets the necessary conditions for insulation.

Example A

Preparation of the conductor: 76 aluminum monofilaments with a diameter of 2.5 mm were compressed and stranded to obtain the inner core of the aluminum conductor.

Preparation of polypropylene graft particles containing acid anhydride groups: blending the following components by mass: 100 parts of polypropylene grafts containing acid anhydride groups obtained in Example 2, antioxidant 1010/168/ Calcium stearate (mass ratio 2:2:1) 0.3 part. Use a twin-screw extruder to granulate, the rotation speed is 300r/min, and the granulation temperature is 210-230°C.

Preparation of conductor shielding layer and insulating layer: Conductor shielding material PSD_WMP-00012 (Zhejiang Wanma Co., Ltd.) and the above-mentioned polypropylene graft particles containing anhydride groups are co-extruded through an extruder outside the conductor core. Cover to form a conductor shielding layer + an electrical insulation layer, or form a conductor shielding layer + an electrical insulation layer + an electrical insulation shielding layer (outer shielding layer), and the extrusion temperature is 190-210°C.

Preparation of the metal shielding layer: 25 T1 copper wires with a diameter of 0.3mm are used to wrap the outer electrical insulating layer (electrical insulating shielding layer) with copper wires to form a metal shielding layer.

Preparation of the inner sheath layer: PVC granules of the brand St-2 (Dongguan Haichuang Electronics Co., Ltd.) were extruded through an extruder outside the metal shielding layer to form an inner sheath layer.

Armoring preparation: Use 50 304 stainless steel wires with a diameter of 6.0mm to make a single-layer steel wire armor, wrap the single-layer steel wire armor leftward on the inner sheath layer, and make the armor tight so that the distance between adjacent steel wires Clearance is minimal.

Preparation of the outer sheath layer: PVC granules of the brand St-2 (Dongguan Haichuang Electronics Co., Ltd.) are extruded through an extruder outside the armor to form an outer sheath layer.

Finally, the high-performance polypropylene cable is obtained. The schematic diagram of the cross-sectional structure of the cable is shown in Fig. 1 .

According to the above method based on the materials in Example 2, a cable with an energy level of 10kV is prepared, the cable conductor cross-sectional area is about 400mm ² , the average thickness of the conductor shielding layer is 1.15mm, the average thickness of the electrical insulation layer is 2.60mm, and the average thickness of the electrical insulation shielding layer The thickness is 1.06mm, the average thickness of the metal shielding layer is 1.00mm, the eccentricity of the cable insulation is 5.1%, the average thickness of the armor is 6.02mm, the average thickness of the inner sheath layer is 2.10mm, and the average thickness of the outer sheath layer is 2.35mm.

Test case A

The cable prepared in Example A was tested. The test results of the electrical conductivity of the main insulation of the cables: the electrical conductivity ratio of each cable at 90°C and 30°C is 44.2. Cable insulation space charge injection test results: The electric field distortion of the cable is 15.4%. DC withstand voltage test result: the cable passed without breakdown and discharge. Load cycle test results: the cable passed without breakdown.

Example B

Conductor preparation: multiple aluminum monofilament conductors are bundled, and then the wires are bundled to make the inner core of the conductor.

The preparation of the polypropylene graft particle that contains acid anhydride group: each component blending of following mass parts: embodiment 1 and embodiment 3-5 obtains the polypropylene graft thing that contains acid anhydride group 100 parts, resists Oxygen agent 1010/168/calcium stearate (mass ratio 2:2:1) 0.3 parts. Use a twin-screw extruder to granulate, the rotation speed is 300r/min, and the granulation temperature is 210-230°C.

Preparation of conductor shielding layer and insulating layer: Conductor shielding material PSD_WMP-00012 (Zhejiang Wanma Co., Ltd.) and the above-mentioned polypropylene graft particles containing anhydride groups are co-extruded through an extruder outside the conductor core. Cover to form a conductor shielding layer+electrical insulation layer, or form a conductor shielding layer+electrical insulation layer+electrical insulation shielding layer (outer shielding layer), and the extrusion temperature is 160-210°C.

Preparation of the metal shielding layer: T1 copper is used to wrap copper tape outside the electrical insulation layer (electrical insulation shielding layer) to form a metal shielding layer.

Preparation of the inner sheath layer: PVC granules of the brand St-2 (Dongguan Haichuang Electronics Co., Ltd.) were extruded through an extruder outside the metal shielding layer to form an inner sheath layer.

Preparation of armor: 304 stainless steel is used to make steel wire armor with a nominal diameter of 1.25mm, and the single-layer armor is wrapped leftward on the inner sheath layer. The armor is tight so that the gap between adjacent steel wires is the smallest. .

Preparation of the outer sheath layer: PVC granules of the brand St-2 (Dongguan Haichuang Electronics Co., Ltd.) are extruded through an extruder outside the armor to form an outer sheath layer.

Finally, the high-performance polypropylene cable is obtained. The schematic diagram of the cross-sectional structure of the cable is shown in Fig. 1 .

According to the above method, cables with an energy level in the range of 6-35kV are prepared based on the materials in Example 1 and Examples 3-5 respectively, the cross-sectional area of the cable conductor is 240-400mm ² , the thickness of the conductor shielding layer is 1-3mm, and the thickness of the electrical insulation layer is 2-8mm, the thickness of the electrical insulation shielding layer is 0.5-1.5mm, the thickness of the armor is 0.5-1mm, the thickness of the inner sheath layer is 1-2mm, and the thickness of the outer sheath layer is not less than 1.8mm.

Test case B

The cables prepared in Example B were tested. The test results of the electrical conductivity of the main insulation of the cables: the electrical conductivity ratios of the cables at 90°C and 30°C are all less than 100. Cable insulation space charge injection test results: the electric field distortion of each cable is less than 20%. DC withstand voltage test results: each cable has no breakdown and discharge phenomenon, and passes. Load cycle test results: all cables have no breakdown phenomenon and pass.

It can be seen that the cable of the present invention that uses polypropylene grafts containing acid anhydride groups as the main insulating layer has a higher working temperature than the existing cables, and can still maintain or even have a high working temperature at a higher working temperature. Higher volume resistivity and stronger breakdown resistance. Under the condition of ensuring the same voltage level and insulation level, the electrical insulation layer made of the polypropylene graft containing anhydride groups has thinner thickness, better heat dissipation and smaller weight than the electrical insulation layer of conventional cables The advantages.

Having described various embodiments of the present invention, the foregoing description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and alterations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Neither the endpoints nor any values of the ranges disclosed herein are limited to such precise ranges or values, and these ranges or values are understood to include values approaching these ranges or values. For numerical ranges, between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, these values Ranges should be considered as specifically disclosed herein.

Claims (83)

1. A polypropylene cable, characterized in that the cable comprises:

at least one conductor and at least one electrically insulating layer surrounding the conductor;

wherein the material of the electric insulating layer is at least one polypropylene graft containing an acid anhydride group;

the polypropylene graft containing an acid anhydride group comprises a structural unit derived from copolymerized polypropylene, a structural unit derived from an acid anhydride monomer and a structural unit derived from an alkenyl-containing polymerized monomer; the content of the structural units derived from the acid anhydride monomer and the olefin-containing polymeric monomer in a grafted state in the acid anhydride group-containing polypropylene graft is 0.1 to 5wt% based on the weight of the acid anhydride group-containing polypropylene graft; and the content of the structural unit which is derived from the acid anhydride monomer and is in a grafted state in the polypropylene graft containing the acid anhydride group is 0.05 to 2wt%.

2. The cable according to claim 1, wherein the anhydride group-containing polypropylene graft has a content of structural units derived from an anhydride monomer and an alkenyl-containing polymerizable monomer in a grafted state of 0.4 to 3wt%.

3. The cable according to claim 1, wherein the content of the structural units derived from an acid anhydride monomer and in a grafted state in the polypropylene graft containing an acid anhydride group is 0.2 to 0.7wt%.

4. The cable of claim 1, wherein the cable has at least one core, each core comprising, in order from the inside to the outside: a conductor, an optional conductor shield layer, an electrically insulating layer, an optional electrically insulating shield layer, an optional metal shield layer.

5. A cable according to claim 4, wherein the cable further comprises an armor and/or jacketing layer.

6. The cable according to claim 4, wherein the cable further comprises a filler layer and/or a tape layer.

7. The cable of claim 1, wherein the cable is a direct current cable or an alternating current cable.

8. The cable of claim 7, wherein the cable is a direct current cable.

9. The cable according to any one of claims 1 to 8, wherein the polypropylene graft containing anhydride groups has at least one of the following characteristics: the melt flow rate under the load of 2.16kg at 230 ℃ is 0.01-30 g/10min; the flexural modulus is 20-900 MPa; the elongation at break is more than or equal to 200 percent; the tensile strength is more than 5MPa.

10. The cable according to claim 9, wherein the polypropylene graft containing an acid anhydride group has a melt flow rate of 0.05 to 20g/10min at 230 ℃ under a load of 2.16 kg.

11. The cable according to claim 10, wherein the polypropylene graft containing an acid anhydride group has a melt flow rate of 0.1 to 10g/10min at 230 ℃ under a load of 2.16 kg.

12. The cable according to claim 11, wherein the polypropylene graft containing an acid anhydride group has a melt flow rate of 0.2 to 5g/10min at 230 ℃ under a load of 2.16 kg.

13. Cable according to claim 9, wherein the polypropylene graft containing anhydride groups has a flexural modulus of from 50 to 600MPa.

14. The cable according to claim 9, wherein the polypropylene graft containing an acid anhydride group has an elongation at break of 300% or more.

15. The cable according to claim 9, wherein the tensile strength of the polypropylene graft containing an acid anhydride group is 10 to 40MPa.

16. The cable according to any one of claims 1 to 8, wherein the polypropylene graft containing anhydride groups has at least one of the following characteristics:

the working temperature of the polypropylene graft containing the anhydride group is more than or equal to 90 ℃;

the breakdown field strength E of the polypropylene graft containing anhydride groups at 90 DEG C _g ≥210kV/mm；

The breakdown field strength E of the polypropylene graft containing anhydride groups at 90 ℃ _g The variation rate of breakdown field intensity delta E/E obtained by dividing the difference delta E of the breakdown field intensity E of the copolymerized polypropylene at 90 ℃ by the breakdown field intensity E of the copolymerized polypropylene at 90 ℃ is more than 1.8%;

-the polypropylene graft containing anhydride groups has a direct volume resistivity p at 90 ℃ at a field strength of 15kV/mm _vg ≥1.5×10 ¹³ Ω·m；

-the polypropylene graft containing anhydride groups has a direct volume resistivity p at 90 ℃ at a field strength of 15kV/mm _vg The direct current volume resistivity rho of the polypropylene copolymer at the temperature of 90 ℃ and the field strength of 15kV/mm _v Ratio ρ of _vg/ ρ _v Greater than 2;

-the polypropylene graft containing anhydride groups has a dielectric constant of greater than 2.0 at 90 ℃ at 50 Hz.

17. The cable according to claim 16, wherein the working temperature of the polypropylene grafts comprising anhydride groups is comprised between 90 and 160 ℃.

18. The cable according to claim 16, wherein the polypropylene grafts comprising anhydride groups have a breakdown field strength E at 90 ℃ _g Is 210-800 kV/mm.

19. The cable according to claim 16, wherein the polypropylene graft containing an anhydride group has a breakdown field strength E at 90 ℃ _g The change rate of breakdown field strength delta E/E obtained by dividing the difference delta E of the breakdown field strength E of the copolymerized polypropylene at 90 ℃ by the breakdown field strength E of the copolymerized polypropylene at 90 ℃ is 2-50%.

20. The cable according to claim 19, wherein the polypropylene grafts comprising anhydride groups have a breakdown field strength E at 90 ℃ _g The change rate of breakdown field strength delta E/E obtained by dividing the difference delta E of the breakdown field strength E of the copolymerized polypropylene at 90 ℃ by the breakdown field strength E of the copolymerized polypropylene at 90 ℃ is 5-35%.

21. The cable according to claim 20, wherein the polypropylene grafts comprising anhydride groups have a breakdown field strength E at 90 ℃ _g The change rate of breakdown field strength delta E/E obtained by dividing the difference delta E of the breakdown field strength E of the copolymerized polypropylene at 90 ℃ by the breakdown field strength E of the copolymerized polypropylene at 90 ℃ is 8-28%.

22. The cable according to claim 16, wherein the polypropylene graft containing anhydride groups has a direct volume resistivity p at 90 ℃ at a field strength of 15kV/mm _vg Is 1.5X 10 ¹³ Ω·m～1.0×10 ²⁰ Ω·m。

23. The cable according to claim 16,the polypropylene graft containing the anhydride group has direct-current volume resistivity rho at 90 ℃ and 15kV/mm field strength _vg The direct current volume resistivity rho of the copolymerized polypropylene at 90 ℃ and 15kV/mm field intensity _v Ratio of (p) _vg/ ρ _v Is 2.1 to 40.

24. The cable according to claim 23, wherein the polypropylene grafts comprising anhydride groups have a direct volume resistivity p at 90 ℃ at a field strength of 15kV/mm _vg The direct current volume resistivity rho of the polypropylene copolymer at the temperature of 90 ℃ and the field strength of 15kV/mm _v Ratio of (p) _vg/ ρ _v Is 2.3 to 20.

25. The cable according to claim 24, wherein the polypropylene grafts comprising anhydride groups have a direct volume resistivity p at 90 ℃ at a field strength of 15kV/mm _vg The direct current volume resistivity rho of the copolymerized polypropylene at 90 ℃ and 15kV/mm field intensity _v Ratio ρ of _vg/ ρ _v Is 2.5 to 10.

26. The cable according to claim 16, wherein the polypropylene graft containing an acid anhydride group has a dielectric constant of 2.1 to 2.5 at 90 ℃ and 50 Hz.

27. The cable according to any one of claims 1 to 8, wherein the co-polypropylene has at least one of the following characteristics: the content of the comonomer is 0.5 to 40mol percent; the content of xylene soluble substances is 2 to 80 weight percent; the content of the comonomer in the soluble substance is 10 to 70 weight percent; the ratio of the soluble matter to the polypropylene is 0.3 to 5.

28. The cable according to claim 27, wherein the copolymerized polypropylene has a comonomer content of 0.5 to 30mol%.

29. The cable according to claim 28, wherein the copolymerized polypropylene has a comonomer content of 4 to 25wt%.

30. The cable according to claim 29, wherein the copolymerized polypropylene has a comonomer content of 4 to 22wt%.

31. The cable according to claim 27, wherein the copolypropylene has a xylene solubles content of 18 to 75wt%.

32. The cable according to claim 31, wherein the copolymerized polypropylene has a xylene solubles content of 30 to 70wt%.

33. The cable according to claim 32, wherein the copolypropylene has a xylene solubles content of 30 to 67wt%.

34. The cable according to claim 27, wherein the copolymerized polypropylene has a comonomer content in solubles of 10 to 50wt%.

35. The cable of claim 34 wherein the copolymerized polypropylene has a comonomer content in solubles from 20 to 35wt%.

36. The cable of claim 27, wherein the intrinsic viscosity ratio of polypropylene to solubles of the copolymerized polypropylene is 0.5 to 3.

37. The cable of claim 36, wherein the intrinsic viscosity ratio of polypropylene to solubles of the copolymerized polypropylene is 0.8 to 1.3.

38. The cable according to any one of claims 1 to 8, wherein the co-polypropylene has at least one of the following characteristics: the melt flow rate under the load of 2.16kg at 230 ℃ is 0.01-60 g/10min; the melting temperature Tm is above 100 ℃; weight average molecular weight of 20X 10 ⁴ ～60×10 ⁴ g/mol。

39. The cable according to claim 38, wherein the melt flow rate of the co-polypropylene is 0.05 to 35g/10min at 230 ℃ under a 2.16kg load.

40. The cable according to claim 39, wherein the melt flow rate of the co-polypropylene is 0.5 to 15g/10min at 230 ℃ under a 2.16kg load.

41. The cable according to claim 40, wherein the melt flow rate of the co-polypropylene is 0.5 to 8g/10min at 230 ℃ under a 2.16kg load.

42. The cable according to claim 38, wherein the melting temperature Tm of the co-polypropylene is between 110 and 180 ℃.

43. The cable according to claim 42, wherein the melting temperature Tm of the co-polypropylene is between 110 and 170 ℃.

44. The cable according to claim 43, wherein the melting temperature Tm of the co-polypropylene is between 120 and 170 ℃.

45. The cable according to claim 44, wherein the melting temperature Tm of the co-polypropylene is comprised between 120 and 166 ℃.

46. Cable according to any one of claims 1 to 8, wherein the comonomer of the co-polypropylene is selected from C other than propylene ₂ -C ₈ At least one of alpha-olefins (b) of (a).

47. The cable of claim 46 wherein the comonomer of the co-polypropylene is selected from at least one of ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, and 1-octene.

48. The cable according to claim 47, wherein the comonomer of the co-polypropylene is ethylene and/or 1-butene.

49. The cable according to claim 48, wherein the co-polypropylene consists of propylene and ethylene.

50. The cable according to claim 1, wherein the alkenyl-containing polymeric monomer is at least one selected from monomers having a structure represented by formula 1,

in the formula 1, R ₁ 、R ₂ 、R ₃ Each independently selected from H, substituted or unsubstituted alkyl; r ₄ Selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, substituted or unsubstituted ester group, substituted or unsubstituted carboxyl, substituted or unsubstituted cycloalkyl or heterocyclic group, cyano.

51. The cable of claim 50, wherein R ₁ 、R ₂ 、R ₃ Each independently selected from H, substituted or unsubstituted C ₁ -C ₆ An alkyl group.

52. The cable of claim 51, wherein R ₁ 、R ₂ 、R ₃ Each independently selected from H, substituted or unsubstituted C ₁ -C ₃ An alkyl group.

53. The cable of claim 50, wherein R ₄ Selected from substituted or unsubstituted C ₁ -C ₂₀ Alkyl, substituted or unsubstituted C ₁ -C ₂₀ Alkoxy, substituted or unsubstituted C ₆ -C ₂₀ Aryl, substituted or unsubstituted C ₁ -C ₂₀ Ester group, substituted or unsubstituted C ₁ -C ₂₀ Carboxy, substituted or unsubstituted C ₃ -C ₂₀ Cycloalkyl or heterocyclic radical, cyano radical, the said substituted radicals being halogen, hydroxy, amino, C ₁ -C ₆ Alkyl radical, C ₃ -C ₆ A cycloalkyl group.

54. The cable of claim 53, wherein R ₄ Selected from substituted or unsubstituted C ₁ -C ₁₂ Alkyl, substituted or unsubstituted C ₁ -C ₁₈ Alkoxy, substituted or unsubstituted C ₆ -C ₁₂ Aryl, substituted or unsubstituted C ₁ -C ₁₂ Ester group, substituted or unsubstituted C ₁ -C ₁₂ Carboxy, substituted or unsubstituted C ₃ -C ₁₂ Cycloalkyl or heterocyclyl, cyano, said substituted radicals being halogen, C ₁ -C ₆ Alkyl radical, C ₃ -C ₆ A cycloalkyl group.

55. The cable according to claim 54, wherein R ₄ Selected from substituted or unsubstituted C ₁ -C ₆ Alkyl, substituted or unsubstituted C ₁ -C ₁₂ Alkoxy, substituted or unsubstituted C ₆ -C ₈ Aryl, substituted or unsubstituted C ₁ -C ₆ Ester group, substituted or unsubstituted C ₁ -C ₆ Carboxy, substituted or unsubstituted C ₃ -C ₆ Cycloalkyl or heterocyclyl, cyano.

56. The cable according to claim 50, wherein the heterocyclic group is selected from imidazolyl, pyrazolyl, carbazolyl, pyrrolidinonyl, pyridyl, piperidyl, caprolactanyl, pyrazinyl, thiazolyl, purinyl, morpholinyl, oxazolinyl.

57. The cable of claim 50, wherein R ₁ 、R ₂ 、R ₃ Each independently selected from H, substituted or unsubstituted C ₁ -C ₆ An alkyl group;

R ₄ selected from the group represented by formula 2 and the group represented by formula 3A group, a group represented by formula 4, a group represented by formula 5, a combination of a group represented by formula 5 and a group represented by formula 6, a heterocyclic group;

in the formula 2, R ⁴ -R ⁸ Each independently selected from H, halogen, hydroxyl, amino, phosphate, sulfonic acid, substituted or unsubstituted C ₁ -C ₁₂ Alkyl, substituted or unsubstituted C ₃ -C ₁₂ Cycloalkyl, substituted or unsubstituted C ₁ -C ₁₂ Alkoxy, substituted or unsubstituted C ₁ -C ₁₂ Ester group of (2), substituted or unsubstituted C ₁ -C ₁₂ The substituted group is selected from halogen, hydroxyl, amino, phosphate, sulfonic group, C ₁ -C ₁₂ Alkyl of (C) ₃ -C ₁₂ Cycloalkyl of (C) ₁ -C ₁₂ Alkoxy group of (C) ₁ -C ₁₂ Ester group of (1), C ₁ -C ₁₂ An amine group of (a);

in formula 3, R ₄ -R ₁₀ Each independently selected from H, halogen, hydroxyl, amino, phosphate, sulfonic acid, substituted or unsubstituted C ₁ -C ₁₂ Alkyl, substituted or unsubstituted C ₃ -C ₁₂ Cycloalkyl, substituted or unsubstituted C ₁ -C ₁₂ Alkoxy, substituted or unsubstituted C ₁ -C ₁₂ Ester group of (1), substituted or unsubstituted C ₁ -C ₁₂ The substituted group is selected from halogen, hydroxyl, amino, phosphate, sulfonic group, C ₁ -C ₁₂ Alkyl of (C) ₃ -C ₁₂ Cycloalkyl of (C) ₁ -C ₁₂ Alkoxy group of (1), C ₁ -C ₁₂ Ester group of (1), C ₁ -C ₁₂ An amino group of (a);

in the formula 4, R ₄ ’-R ₁₀ ' Each is independently selected from H, halogen, hydroxyl, amino, phosphate, sulfonate, substituted or unsubstituted C ₁ -C ₁₂ Alkyl, substituted or unsubstituted C ₃ -C ₁₂ Cycloalkyl, substituted or unsubstituted C ₁ -C ₁₂ Alkoxy, substituted or unsubstituted C ₁ -C ₁₂ Ester group of (2), substituted or unsubstituted C ₁ -C ₁₂ The substituted group is selected from halogen, hydroxyl, amino, phosphate, sulfonic group, C ₁ -C ₁₂ Alkyl of (C) ₃ -C ₁₂ Cycloalkyl of (C) ₁ -C ₁₂ Alkoxy group of (C) ₁ -C ₁₂ Ester group of (1), C ₁ -C ₁₂ An amino group of (a);

in the formula 5, R _m Selected from the following substituted or unsubstituted groups: c ₁ -C ₂₀ Straight chain alkyl, C ₃ -C ₂₀ Branched alkyl radical, C ₃ -C ₁₂ Cycloalkyl radical, C ₃ -C ₁₂ Epoxyalkyl, C ₃ -C ₁₂ An alkylene oxide alkyl group, the substituted group being at least one selected from halogen, amino and hydroxyl.

58. The cable of claim 57, wherein R in formula 2 ⁴ -R ⁸ Each independently selected from H, halogen, hydroxy, amino, substituted or unsubstituted C ₁ -C ₆ Alkyl, substituted or unsubstituted C ₁ -C ₆ Alkoxy group of (2).

59. The cable of claim 57, wherein R in formula 3 ₄ -R ₁₀ Each independently selected from H, halogen, hydroxy, amino, substituted or unsubstituted C ₁ -C ₆ Alkyl, substituted or unsubstituted C ₁ -C ₆ The substituted radical is selected from halogen, hydroxyl, amino, C ₁ -C ₆ Alkyl of (C) ₁ -C ₆ Alkoxy group of (2).

60. The cable of claim 57, wherein R in formula 4 ₄ ’-R ₁₀ ' Each is independently selected from H, halogen, hydroxy, amino, substituted or unsubstituted C ₁ -C ₆ Alkyl, substituted or unsubstituted C ₁ -C ₆ The substituted radical is selected from halogen, hydroxyl, amino, C ₁ -C ₆ Alkyl of (C) ₁ -C ₆ Alkoxy group of (2).

61. The cable according to claim 57, wherein the alkenyl-containing polymeric monomer is selected from at least one of vinyl acetate, styrene, alpha-methyl styrene, (meth) acrylate, vinyl alkyl ether, vinyl pyrrolidone, vinyl pyridine, vinyl imidazole, and acrylonitrile.

62. The cable according to claim 61, wherein the (meth) acrylate is at least one of methyl (meth) acrylate, ethyl (meth) acrylate, and glycidyl (meth) acrylate.

63. The cable according to claim 61, wherein the alkenyl-containing polymeric monomer is selected from vinyl acetate, styrene, or alpha-methylstyrene.

64. The cable according to claim 63, wherein the polymerized monomer containing alkenyl groups is styrene.

65. The cable according to any one of claims 1 to 8, wherein the molar ratio of structural units derived from anhydride monomers to structural units derived from alkenyl-containing polymerized monomers in the anhydride group-containing polypropylene graft is 1:1 to 20.

66. The cable according to claim 65, wherein the anhydride group-containing polypropylene graft has a molar ratio of structural units derived from an anhydride monomer to structural units derived from an alkenyl-containing polymerized monomer of 1:1 to 10.

67. Cable according to any one of claims 1 to 8, wherein the anhydride is selected from anhydrides having at least one olefinic unsaturation.

68. The cable according to claim 67, wherein the anhydride is selected from maleic anhydride and/or itaconic anhydride.

69. The cable according to claim 68, wherein the anhydride is maleic anhydride.

70. The cable according to any one of claims 1 to 8, wherein the polypropylene graft containing an acid anhydride group is prepared by graft reaction of a copolymerized polypropylene, an acid anhydride monomer and an alkenyl-containing polymeric monomer.

71. The cable according to claim 70, wherein the preparation process of the polypropylene graft containing an anhydride group comprises: and (2) carrying out grafting reaction on the reaction mixture comprising the polypropylene copolymer, the anhydride monomer and the alkenyl-containing polymerized monomer in the presence of inert gas to obtain the polypropylene graft containing the anhydride group.

72. The cable according to claim 71, wherein the reaction mixture further comprises a free radical initiator.

73. The cable according to claim 72, wherein the free radical initiator is selected from peroxide based free radical initiators and/or azo based free radical initiators.

74. The cable according to claim 73, wherein the peroxide-based free radical initiator is selected from at least one of dibenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, lauroyl peroxide, t-butyl peroxybenzoate, diisopropyl peroxydicarbonate, t-butyl peroxy (2-ethylhexanoate) and dicyclohexyl peroxydicarbonate; the azo free radical initiator is azobisisobutyronitrile and/or azobisisoheptonitrile.

75. The cable according to claim 72, wherein the ratio of the mass of the radical initiator to the total mass of the anhydride monomer and the alkenyl-containing polymerized monomer is from 0.1 to 10.

76. The cable according to claim 75, wherein the ratio of the mass of the radical initiator to the total mass of the anhydride monomer and the alkenyl-containing polymerized monomer is from 0.5 to 5.

77. The cable according to claim 71, wherein the mass ratio of the total mass of the acid anhydride monomer and the alkenyl-containing polymeric monomer to the copolymerized polypropylene is 0.1 to 8.

78. The cable according to claim 77, wherein the mass ratio of the total mass of the acid anhydride monomer and the alkenyl-containing polymeric monomer to the copolymerized polypropylene is from 0.3 to 5.

79. The cable according to claim 71, wherein the temperature of the grafting reaction is between 30 and 130 ℃; the time is 0.5 to 10 hours.

80. The cable according to claim 79, wherein the temperature of the grafting reaction is 60-120 ℃; the time is 1-5 h.

81. The cable according to any one of claims 71-80, wherein the reaction mixture further comprises at least one of the following components: the modified polypropylene composite material comprises a dispersing agent, an interfacial agent and an organic solvent, wherein the mass content of the dispersing agent is 50-300% of the mass of the copolymerized polypropylene, the mass content of the interfacial agent is 1-30% of the mass of the copolymerized polypropylene, and the mass content of the organic solvent is 1-35% of the mass of the copolymerized polypropylene.

82. The cable according to claim 81, wherein the preparation method comprises the steps of:

a. placing the copolymerization polypropylene in a closed reactor for inert gas replacement;

b. adding a free radical initiator, an anhydride monomer and an alkenyl-containing polymerization monomer into the closed reactor, and stirring and mixing;

c. optionally adding an interfacial agent and optionally swelling the reaction system;

d. optionally adding a dispersant, heating the reaction system to the grafting reaction temperature, and carrying out grafting reaction;

e. after the reaction is finished, optionally filtering and drying to obtain the polypropylene graft containing the anhydride group.

83. The cable according to claim 81, wherein the preparation method comprises the steps of:

a. placing the copolymerization polypropylene in a closed reactor for inert gas replacement;

b. mixing an organic solvent and a free radical initiator, and adding the mixture into the closed reactor;

c. removing the organic solvent;

d. adding an anhydride monomer and an alkenyl-containing polymeric monomer, optionally adding an interfacial agent, and optionally swelling the reaction system;

e. optionally adding a dispersant, heating the reaction system to the grafting reaction temperature, and carrying out grafting reaction;

f. after the reaction is finished, optionally filtering and drying to obtain the polypropylene graft containing the anhydride group.

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