Room-temperature self-crosslinking flame-retardant insulating material and preparation method thereof

Abstract

The invention relates to the technical field of wire and cable insulating materials, and provides a room-temperature self-crosslinking flame-retardant insulating material and a preparation method thereof.The preparation method comprises the steps that a magnetic metal hydroxide flame retardant is prepared through a sol-gel method, and modified vinyl silane is prepared through a ring-opening polymerization reaction; the preparation method comprises the following steps: performing ordered grafting granulation on polyolefin resin, a magnetic metal hydroxide flame retardant and modified vinyl silane to prepare matrix granules; and blending the matrix granules with the catalytic granules, carrying out extrusion molding on the blended granules, and standing at room temperature to obtain the room-temperature self-crosslinking flame-retardant insulating material. According to the room-temperature self-crosslinking flame-retardant insulated cable and the preparation method thereof, the flame retardant property can be improved, the crosslinking efficiency and cost can be optimized, and the mechanical property and the insulating property can be optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of wire and cable insulation materials, and in particular to a room temperature self-crosslinking flame retardant insulation material and a preparation method thereof. Background Art

[0002] In recent years, cross-linked polyolefin insulated cables have begun to be widely used in the field of building electrical systems. In practical applications, cross-linked polyolefin insulated cables have the following shortcomings: 1. In order to improve the flame retardancy of the insulation, flame retardants are added to the insulating polymer matrix material. In order to overcome the local failure of the flame retardant performance caused by the uneven distribution of the flame retardant, it is necessary to excessively compound the flame retardant in the polymer matrix, which not only increases the material cost but also leads to waste of resources. 2. The addition of flame retardants will have an adverse effect on the insulating electrical properties and mechanical properties of the matrix polymer material, affecting the overall performance and service life of the cable. 3. The existing cross-linking methods are divided into chemical cross-linking and physical cross-linking. Chemical cross-linking includes silane warm water cross-linking and silane vapor cross-linking. Physical cross-linking includes electron irradiation cross-linking and ultraviolet light cross-linking. The chemical cross-linking method has a long process cycle and high energy consumption, and the temperature and time need to be strictly controlled during the cross-linking process to prevent incomplete or excessive cross-linking. The physical cross-linking method requires special equipment, has high requirements for the operating environment and personnel protection, and is costly.

[0003] Chinese patent publication number CN11775757176A discloses a B1-class silane self-crosslinking low-smoke halogen-free insulating material, its preparation method and application, and Chinese patent publication number CN118165401A discloses a flame-retardant silane self-crosslinking insulating material, its preparation method and application. In actual applications, these two schemes adopt the traditional silane self-crosslinking method, which requires water molecules in the air to enter the material to generate -Si-OH, and then -Si-OH and -Si-OH undergo dehydration condensation to form a crosslinked network. This method requires long-term storage and has high requirements for environmental humidity.

[0004] Therefore, how to improve the uniformity of the distribution of flame retardants in the polymer matrix, reduce the proportion of flame retardants and their adverse effects on the polymer matrix while ensuring flame retardant properties, improve cross-linking efficiency and reduce cross-linking costs, is a technical problem that needs to be urgently solved in the current cross-linked polyolefin insulated cables. Summary of the Invention

[0005] In view of this, in order to overcome the deficiencies of the prior art, the present invention aims to provide a room temperature self-crosslinking flame retardant insulating material and a preparation method thereof.

[0006] According to a first aspect of the present invention, a method for preparing a room-temperature self-crosslinking flame-retardant insulating material is provided, the method comprising: preparing a magnetic metal hydroxide flame retardant by a sol-gel method, preparing a modified vinyl silane by a ring-opening polymerization reaction; orderly grafting and granulating a polyolefin resin, a magnetic metal hydroxide flame retardant and a modified vinyl silane to obtain a base pellet; blending the base pellet with a catalytic pellet, extruding the blended pellets, and allowing the blended pellets to stand at room temperature to obtain a room-temperature self-crosslinking flame-retardant insulating material.

[0007] Optionally, in the preparation method of the room temperature self-crosslinking flame-retardant insulating material of the present application, a magnetic metal hydroxide flame retardant is prepared by a sol-gel method, including: dispersing magnetic metal oxide nanoparticles into a hexahydrate magnesium nitrate solution to form a mixed solution, hydrolyzing the mixed solution under alkaline conditions to form a mixed gel, washing, drying and ball milling the mixed gel to obtain a magnetic metal hydroxide flame retardant.

[0008] Optionally, in the preparation method of the room-temperature self-crosslinking flame-retardant insulating material of the present application, a magnetic metal hydroxide flame retardant is prepared by a sol-gel method, including: preparing 0.5 mol / L of magnesium nitrate hexahydrate solution and 0.02 mol / L of ferroferric oxide nanoparticle dispersion respectively, mixing the ferroferric oxide nanoparticle dispersion into the magnesium nitrate hexahydrate solution at a volume ratio of 1:2 to form a mixed solution, adjusting the pH value of the mixed solution to 5, adding ammonia solution with a mass fraction of 25% to the mixed solution, adjusting the pH value of the solution system to 9, and obtaining a mixed gel after standing for 20 hours, washing the mixed gel and drying it at 85°C for 3 hours, and ball milling the dried gel powder at 400 rpm to obtain a magnetic magnesium hydroxide flame retardant.

[0009] Optionally, in the preparation method of the room-temperature self-crosslinking flame-retardant insulating material of the present application, modified vinyl silane is prepared by ring-opening polymerization, including: adding 30 parts by weight of dimethylsiloxane ring, 2 parts by weight of potassium hydroxide and 20 parts by weight of ethanol to a reactor, heating to 80°C and stirring for 30 minutes, adding 5 parts by weight of vinyl silane to the reactor, heating to 110°C and stirring for 3 hours, and distilling the stirred reaction product under reduced pressure to obtain modified vinyl silane.

[0010] Optionally, in the preparation method of the room temperature self-crosslinking flame-retardant insulating material of the present application, polyolefin resin, magnetic metal hydroxide flame retardant and modified vinyl silane are orderly grafted and granulated to prepare matrix granules, including: stirring and blending polyolefin resin, magnetic magnesium hydroxide flame retardant, modified vinyl silane, diisopropylbenzene peroxide and ethyl dimethylaminobenzoate in a ratio of parts by weight, electromagnetically stirring the blended material, extruding and granulating the electromagnetically stirred blended material, and setting an ordered magnetic field consistent with the extrusion molding direction on the extrusion molding path, and controlling the distribution of the magnetic metal hydroxide flame retardant in the molding material by the ordered magnetic field.

[0011] Optionally, in the preparation method of the room temperature self-crosslinking flame-retardant insulating material of the present application, 100 parts by weight of polyolefin resin, 18-25 parts by weight of magnetic magnesium hydroxide flame retardant, 2.8 parts by weight of modified vinyl silane, 1.2 parts by weight of diisopropylbenzene peroxide and 0.8 parts by weight of ethyl dimethylaminobenzoate are stirred and blended, the electromagnetic stirring speed is 500 rpm, and the electromagnetic stirring time is 35 minutes.

[0012] Optionally, in the preparation method of the room-temperature self-cross-linking flame-retardant insulating material of the present application, the magnetic field strength of the ordered magnetic field is 1200 mT, and the range of the ordered magnetic field covers the feeding section, compression section, homogenization section and extrusion die section of extrusion molding. The temperature of the feeding section is 135-150°C, the temperature of the compression section is 155-162°C, the temperature of the homogenization section is 145-158°C, and the temperature of the extrusion die section is 135-160°C.

[0013] Optionally, in the method for preparing the room temperature self-crosslinking flame-retardant insulating material of the present application, the catalytic granules are prepared by extrusion melt granulation of 100 parts by weight of polyolefin resin and 0.8 parts by weight of dibutyltin dilaurate.

[0014] Optionally, in the preparation method of the room-temperature self-crosslinking flame-retardant insulating material of the present application, 100 parts by weight of base pellets and 5.5-11 parts by weight of catalytic pellets are uniformly blended in parts by weight, and the blended pellets are extruded and molded. The temperature of the feeding section of the extrusion molding is 120-150°C, the temperature of the compression section is 155-182°C, the temperature of the homogenization section is 145-175°C, the temperature of the extrusion die section is 125-165°C, and the room-temperature self-crosslinking flame-retardant insulating material is obtained after standing at room temperature for 28 hours.

[0015] According to a second aspect of the present invention, a room temperature self-crosslinking flame retardant insulating material is provided. The room temperature self-crosslinking flame retardant insulating material is prepared according to the above method.

[0016] The room temperature self-crosslinking flame-retardant insulating material and the preparation method thereof of the present invention have the following beneficial technical effects: 1. Improve flame retardant properties 1. Uniform distribution of flame retardants: By using magnetic metal hydroxide flame retardants and combining them with an ordered magnetic field to control their distribution in the molding material, a uniform and orderly distribution of the flame retardant in the polymer matrix is ​​achieved. This uniform distribution avoids the problem of local flame retardant failure caused by uneven distribution of flame retardants in the existing technology, thereby significantly improving the overall flame retardant properties of the material.

[0017] 2. Reduce the amount of flame retardant used: On the basis of achieving uniform distribution, the amount of flame retardant used is reduced. Compared with the traditional technology that requires excessive addition of flame retardant to compensate for the lack of uneven distribution, the present invention reduces the proportion of flame retardant while improving the flame retardant performance, thereby reducing the adverse effects on the insulating electrical properties and mechanical properties of the base polymer material.

[0018] 3. Meet high-standard flame retardant requirements: After testing, the room-temperature self-crosslinking flame-retardant insulation material prepared by the present invention has an oxygen index of not less than 32%, and a smoke density of not more than 31 under flame conditions. The prepared cable has passed the "GB / T 18380.12-2022" single insulated wire and cable flame vertical spread test, indicating that its flame retardant performance meets high-standard requirements.

[0019] 2. Optimizing cross-linking efficiency and cost 1. Submit crosslinking quality: This invention utilizes a grafting reaction and condensation reaction between modified vinyl silane and polyolefin to achieve room-temperature self-crosslinking. Compared to traditional chemical crosslinking (such as silane warm water crosslinking and silane steam crosslinking), it does not require high temperatures and steam environments, thus avoiding the problems of incomplete or excessive crosslinking caused by improper temperature and time control. Compared to physical crosslinking (such as electron irradiation crosslinking and UV light crosslinking), it does not require specialized equipment, reduces the requirements for the operating environment and personnel protection, and significantly reduces crosslinking costs.

[0020] 2. Improved cross-linking efficiency: Room temperature self-cross-linking technology allows the material to complete cross-linking even when left at room temperature, significantly shortening the cross-linking time and improving production efficiency. In this invention, cross-linking is completed after just 40 hours of standing at room temperature, whereas traditional cross-linking methods may require longer time and more complex process conditions.

[0021] 3. Improved process adaptability: The cross-linking method of the present invention has low dependence on environmental conditions and can be stably carried out under a wider range of environmental conditions, thereby improving the adaptability and controllability of the production process and being more suitable for large-scale industrial production.

[0022] 3. Optimize mechanical properties and insulation properties 1. Improved Mechanical Properties: By optimizing the distribution and crosslinking of the flame retardant, this invention reduces the amount of flame retardant used while better preserving the original mechanical properties of the polyolefin resin. Furthermore, the grafting of modified vinyl silane further enhances the material's mechanical properties, achieving a tensile strength of no less than 15.6 MPa and an elongation at break of no less than 170%.

[0023] 2. Maintaining insulation electrical properties: While improving flame retardancy and mechanical properties, the material of the present invention still maintains excellent insulation electrical properties with a volume resistivity of not less than 1.1×10 12 Ω·m, volume resistivity at 150℃ is not less than 2.8×10 11 Ω·m, and the dielectric strength is not less than 25MV / m, which meets the high requirements of insulation performance for wire and cable insulation materials.

[0024] 3. Balanced Comprehensive Performance: This invention achieves a good balance between flame retardancy, mechanical properties, and insulation electrical properties. Compared to existing technologies that struggle to balance flame retardancy, mechanical properties, and processing performance, this invention achieves a better balance across multiple performance indicators by optimizing the material formulation and preparation process, making it more suitable for use in the field of wire and cable insulation materials with high performance requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is an example diagram of a technical path for the preparation method of a room temperature self-crosslinking flame-retardant insulating material according to Example 1 of the present application; Figure 2 This is a SEM morphology of the gel powder prepared according to Example 2 of the present application; Figure 3 This is a SEM morphology image of the magnetic magnesium hydroxide flame retardant prepared according to Example 2 of the present application; Figure 4 This is an example diagram of XRD phase attribution of the magnetic magnesium hydroxide flame retardant prepared according to Example 3 of the present application; Figure 5 This is a key peak marker diagram of the magnetic magnesium hydroxide flame retardant prepared according to Example 3 of the present application. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments may be combined with each other; and, based on the embodiments in this disclosure, all other embodiments obtained by persons of ordinary skill in the art without creative work are within the scope of protection of this disclosure.

[0029] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0030] Example 1 Figure 1 This is an example diagram of the technical path of the method for preparing the room temperature self-crosslinking flame retardant insulation material according to Example 1 of the present application.

[0031] like Figure 1 As shown, in this embodiment, the preparation method of the room temperature self-crosslinking flame retardant insulation material is implemented in the following manner: First, this example prepared a magnetic metal hydroxide flame retardant using a sol-gel method. Magnetic metal oxide nanoparticles were dispersed in a magnesium nitrate hexahydrate solution to form a mixed solution. The mixed solution was hydrolyzed under alkaline conditions to form a mixed gel. The mixed gel was then washed, dried, and ball-milled to produce the magnetic metal hydroxide flame retardant.

[0032] As an optional example, in this embodiment, the magnetic metal oxide nanoparticles are ferroferric oxide nanoparticles with an average particle size of 100 nm. The ferroferric oxide nanoparticle dispersion is prepared by dispersing the ferroferric oxide nanoparticles in ethanol, and the magnesium nitrate hexahydrate solution is prepared by dissolving magnesium nitrate hexahydrate in deionized water. The ferroferric oxide nanoparticle dispersion is slowly added to the magnesium nitrate hexahydrate solution to form a mixed solution. The mixed solution generates a magnesium hydroxide precipitate under alkaline conditions, and the ferroferric oxide nanoparticles are uniformly dispersed in the magnesium hydroxide precipitate. A stable mixed gel with a three-dimensional network structure is formed by standing. The mixed gel is washed and dried, and the dried gel powder is ball-milled to obtain a magnetic magnesium hydroxide flame retardant with a reasonable particle size.

[0033] Next, this example prepares modified vinyl silanes via ring-opening polymerization. In this example, dimethylsiloxane rings undergo ring-opening polymerization in the presence of potassium hydroxide to form linear or branched polysiloxane chains. These chains then react with vinyl silane to form modified vinyl silanes with both vinyl double bonds and amino groups.

[0034] As an optional example, in this embodiment, 30 parts by weight of dimethylsiloxane ring, 2 parts by weight of potassium hydroxide and 20 parts by weight of ethanol are added to a reactor, the temperature is raised to 80°C and stirred for 30 minutes, 5 parts by weight of vinyl silane is added to the reactor, the temperature is raised to 110°C and stirred for 3 hours, and the stirred reaction product is distilled under reduced pressure to obtain modified vinyl silane.

[0035] Then, in this embodiment, polyolefin resin, magnetic metal hydroxide flame retardant and modified vinyl silane are subjected to orderly grafting and granulation to prepare base granules.

[0036] As an optional example, in this embodiment, polyolefin resin, magnetic magnesium hydroxide flame retardant, modified vinyl silane, diisopropylbenzene peroxide and ethyl dimethylaminobenzoate are stirred and blended in a ratio of parts by weight, the blended material is electromagnetically stirred, the electromagnetically stirred blended material is extruded and granulated, and an ordered magnetic field consistent with the extrusion direction is set on the extrusion molding path.

[0037] It should be noted that in this embodiment, dicumyl peroxide decomposes during the extrusion process, generating free radicals. These free radicals can attack the polyolefin backbone, breaking it and forming active sites. Ethyl dimethylaminobenzoate can further synergistically increase the number of active sites on the polyolefin backbone. The vinyl double bonds of the modified vinyl silane react with the active sites on the polyolefin backbone to form covalent bonds, grafting the silane groups onto the polyolefin backbone.

[0038] In this embodiment, an ordered magnetic field consistent with the extrusion molding direction is set on the extrusion molding path, and the distribution of the magnetic metal hydroxide flame retardant in the molding material is controlled by the ordered magnetic field, thereby achieving a uniform and orderly distribution of the metal hydroxide flame retardant in the extruded molding material, avoiding the deficiency of the prior art that excessive compounding is required to compensate for the uneven distribution of the flame retardant phase in the polymer matrix, resulting in local failure of the flame retardant performance. While improving the uniformity of the flame retardant phase dispersion and the flame retardant properties of the overall material, this embodiment reduces the proportion of the flame retardant phase, thereby reducing the adverse effects of the flame retardant on the insulating electrical properties and mechanical properties of the matrix polymer material.

[0039] Finally, in this embodiment, the base granules and the catalytic granules are blended, the blended granules are extruded and formed, and the room temperature self-crosslinking flame-retardant insulating material is obtained after standing at room temperature. It should be noted that, in this embodiment, the crosslinking of the polyolefin molecular chains is achieved by the grafting reaction and condensation reaction of the modified vinyl silane and the polyolefin. As an optional example, in this embodiment, the catalytic granules are prepared from polyolefin resin and dibutyltin dilaurate. During the extrusion molding process, the dibutyltin dilaurate in the catalytic granules can enable the silane groups grafted onto the polyolefin main chain in the base granules to combine with the amino groups of the modified vinyl silane in the condensation reaction to form crosslinking points, so that crosslinking occurs between the polyolefin molecular chains to form a three-dimensional network structure.

[0040] In the prior art, a catalyst and water are used to induce a hydrolysis reaction of silane groups to form a silanol intermediate. This silanol intermediate then undergoes a condensation reaction to form silicon-oxygen bonds, which crosslinks the polymer chains. This embodiment avoids the hydrolysis reaction, thus achieving crosslinking without the need for high temperatures and a steam environment, enabling room-temperature self-crosslinking.

[0041] Example 2 Preparation method of room temperature self-crosslinking flame retardant insulation material of Example 2 of the present application: 1. Preparation of magnetic magnesium hydroxide flame retardant: 0.5 mol / L magnesium nitrate hexahydrate solution and 0.02 mol / L ferrosoferric oxide nanoparticle dispersion were prepared respectively, and the ferrosoferric oxide nanoparticle dispersion was mixed with the magnesium nitrate hexahydrate solution at a volume ratio of 1:2 to form a mixed solution, and the pH value of the mixed solution was adjusted to 5. A 25% by mass ammonia aqueous solution was added to the mixed solution, and the pH value of the solution system was adjusted to 9. After standing for 20 hours, a mixed gel was obtained. The mixed gel was washed and dried at 85°C for 3 hours. The dried gel powder was ball-milled at 400 rpm to obtain a magnetic magnesium hydroxide flame retardant with an average particle size of 150 nm.

[0042] 2. Preparation of modified vinyl silane: 30 parts by weight of dimethylsiloxane ring, 2 parts by weight of potassium hydroxide and 20 parts by weight of ethanol were added to a reactor, heated to 80°C and stirred for 30 minutes, 5 parts by weight of vinyl silane was added to the reactor, heated to 110°C and stirred for 3 hours, and the stirred reaction product was distilled under reduced pressure to obtain modified vinyl silane.

[0043] 3. Preparation of base pellets: 100 parts by weight of polyolefin resin, 18 parts by weight of magnetic magnesium hydroxide flame retardant, 2.8 parts by weight of modified vinyl silane, 1.2 parts by weight of dicumyl peroxide, and 0.8 parts by weight of ethyl dimethylaminobenzoate were stirred and blended. The blended material was electromagnetically stirred at a speed of 500 rpm for 35 minutes. The electromagnetically stirred blended material was extruded and granulated. An ordered magnetic field was set on the extrusion molding path in the same direction as the extrusion molding. The ordered magnetic field controlled the distribution of the magnetic metal hydroxide flame retardant in the molding material. The magnetic field strength of the ordered magnetic field was 1200 mT. The ordered magnetic field covered the feeding section, compression section, homogenization section, and extrusion die section of the extrusion molding. The temperature of the feeding section was 135-150°C, the temperature of the compression section was 155-162°C, the temperature of the homogenization section was 145-158°C, and the temperature of the extrusion die section was 135-160°C.

[0044] 4. Preparation of catalytic pellets: 100 parts by weight of polyolefin resin and 0.8 parts by weight of dibutyltin dilaurate were uniformly mixed, and catalytic pellets were prepared by extrusion melt granulation.

[0045] 5. Preparation of room temperature self-crosslinking flame retardant insulating material: According to the ratio of parts by weight, 100 parts by weight of base pellets and 5.5 parts by weight of catalytic pellets are uniformly blended, and the blended pellets are extruded. The temperature of the feeding section of the extrusion molding is 120-150°C, the temperature of the compression section is 155-182°C, the temperature of the homogenization section is 145-175°C, and the temperature of the extrusion die section is 125-165°C. After standing at room temperature for 28 hours, the room temperature self-crosslinking flame retardant insulating material is obtained.

[0046] Example 3 Preparation method of room temperature self-crosslinking flame retardant insulation material of Example 3 of the present application: 1. Preparation of magnetic magnesium hydroxide flame retardant: 0.5 mol / L magnesium nitrate hexahydrate solution and 0.02 mol / L ferrosoferric oxide nanoparticle dispersion were prepared respectively, and the ferrosoferric oxide nanoparticle dispersion was mixed with the magnesium nitrate hexahydrate solution at a volume ratio of 1:2 to form a mixed solution, and the pH value of the mixed solution was adjusted to 5. A 25% by mass ammonia aqueous solution was added to the mixed solution, and the pH value of the solution system was adjusted to 9. After standing for 20 hours, a mixed gel was obtained. The mixed gel was washed and dried at 85°C for 3 hours. The dried gel powder was ball-milled at 400 rpm to obtain a magnetic magnesium hydroxide flame retardant with an average particle size of 150 nm.

[0047] 2. Preparation of modified vinyl silane: 30 parts by weight of dimethylsiloxane ring, 2 parts by weight of potassium hydroxide and 20 parts by weight of ethanol were added to a reactor, heated to 80°C and stirred for 30 minutes, 5 parts by weight of vinyl silane was added to the reactor, heated to 110°C and stirred for 3 hours, and the stirred reaction product was distilled under reduced pressure to obtain modified vinyl silane.

[0048] 3. Preparation of base pellets: 100 parts by weight of polyolefin resin, 20 parts by weight of magnetic magnesium hydroxide flame retardant, 2.8 parts by weight of modified vinyl silane, 1.2 parts by weight of dicumyl peroxide, and 0.8 parts by weight of ethyl dimethylaminobenzoate were stirred and blended. The blended material was electromagnetically stirred at a speed of 500 rpm for 35 minutes. The electromagnetically stirred blended material was extruded and granulated. An ordered magnetic field was set on the extrusion molding path in the same direction as the extrusion molding. The ordered magnetic field controlled the distribution of the magnetic metal hydroxide flame retardant in the molding material. The magnetic field strength of the ordered magnetic field was 1200 mT. The ordered magnetic field covered the feeding section, compression section, homogenization section, and extrusion die section of the extrusion molding. The temperature of the feeding section was 135-150°C, the temperature of the compression section was 155-162°C, the temperature of the homogenization section was 145-158°C, and the temperature of the extrusion die section was 135-160°C.

[0049] 4. Preparation of catalytic pellets: 100 parts by weight of polyolefin resin and 0.8 parts by weight of dibutyltin dilaurate were uniformly mixed, and catalytic pellets were prepared by extrusion melt granulation.

[0050] 5. Preparation of room temperature self-crosslinking flame retardant insulating material: According to the ratio of parts by weight, 100 parts by weight of base pellets and 6 parts by weight of catalytic pellets are uniformly blended, and the blended pellets are extruded. The temperature of the feeding section of the extrusion molding is 120-150°C, the temperature of the compression section is 155-182°C, the temperature of the homogenization section is 145-175°C, and the temperature of the extrusion die section is 125-165°C. After standing at room temperature for 28 hours, the room temperature self-crosslinking flame retardant insulating material is obtained.

[0051] Example 4 Preparation method of room temperature self-crosslinking flame retardant insulation material of Example 4 of the present application: 1. Preparation of magnetic magnesium hydroxide flame retardant: 0.5 mol / L magnesium nitrate hexahydrate solution and 0.02 mol / L ferrosoferric oxide nanoparticle dispersion were prepared respectively, and the ferrosoferric oxide nanoparticle dispersion was mixed with the magnesium nitrate hexahydrate solution at a volume ratio of 1:2 to form a mixed solution, and the pH value of the mixed solution was adjusted to 5. A 25% by mass ammonia aqueous solution was added to the mixed solution, and the pH value of the solution system was adjusted to 9. After standing for 20 hours, a mixed gel was obtained. The mixed gel was washed and dried at 85°C for 3 hours. The dried gel powder was ball-milled at 400 rpm to obtain a magnetic magnesium hydroxide flame retardant with an average particle size of 150 nm.

[0052] 2. Preparation of modified vinyl silane: 30 parts by weight of dimethylsiloxane ring, 2 parts by weight of potassium hydroxide and 20 parts by weight of ethanol were added to a reactor, heated to 80°C and stirred for 30 minutes, 5 parts by weight of vinyl silane was added to the reactor, heated to 110°C and stirred for 3 hours, and the stirred reaction product was distilled under reduced pressure to obtain modified vinyl silane.

[0053] 3. Preparation of base pellets: 100 parts by weight of polyolefin resin, 21 parts by weight of magnetic magnesium hydroxide flame retardant, 2.8 parts by weight of modified vinyl silane, 1.2 parts by weight of dicumyl peroxide, and 0.8 parts by weight of ethyl dimethylaminobenzoate were stirred and blended. The blended material was electromagnetically stirred at a speed of 500 rpm for 35 minutes. The electromagnetically stirred blended material was extruded and granulated. An ordered magnetic field was set on the extrusion molding path in the same direction as the extrusion molding. The ordered magnetic field controlled the distribution of the magnetic metal hydroxide flame retardant in the molding material. The magnetic field strength of the ordered magnetic field was 1200 mT. The ordered magnetic field covered the feeding section, compression section, homogenization section, and extrusion die section of the extrusion molding. The temperature of the feeding section was 135-150°C, the temperature of the compression section was 155-162°C, the temperature of the homogenization section was 145-158°C, and the temperature of the extrusion die section was 135-160°C.

[0054] 4. Preparation of catalytic pellets: 100 parts by weight of polyolefin resin and 0.8 parts by weight of dibutyltin dilaurate were uniformly mixed, and catalytic pellets were prepared by extrusion melt granulation.

[0055] 5. Preparation of room temperature self-crosslinking flame retardant insulating material: According to the ratio of parts by weight, 100 parts by weight of base pellets and 8 parts by weight of catalytic pellets are uniformly blended, and the blended pellets are extruded. The temperature of the feeding section of the extrusion molding is 120-150°C, the temperature of the compression section is 155-182°C, the temperature of the homogenization section is 145-175°C, and the temperature of the extrusion die section is 125-165°C. After standing at room temperature for 28 hours, the room temperature self-crosslinking flame retardant insulating material is obtained.

[0056] Example 5 Preparation method of room temperature self-crosslinking flame retardant insulation material of Example 5 of the present application: 1. Preparation of magnetic magnesium hydroxide flame retardant: 0.5 mol / L magnesium nitrate hexahydrate solution and 0.02 mol / L ferrosoferric oxide nanoparticle dispersion were prepared respectively, and the ferrosoferric oxide nanoparticle dispersion was mixed with the magnesium nitrate hexahydrate solution at a volume ratio of 1:2 to form a mixed solution, and the pH value of the mixed solution was adjusted to 5. A 25% by mass ammonia aqueous solution was added to the mixed solution, and the pH value of the solution system was adjusted to 9. After standing for 20 hours, a mixed gel was obtained. The mixed gel was washed and dried at 85°C for 3 hours. The dried gel powder was ball-milled at 400 rpm to obtain a magnetic magnesium hydroxide flame retardant with an average particle size of 150 nm.

[0057] 2. Preparation of modified vinyl silane: 30 parts by weight of dimethylsiloxane ring, 2 parts by weight of potassium hydroxide and 20 parts by weight of ethanol were added to a reactor, heated to 80°C and stirred for 30 minutes, 5 parts by weight of vinyl silane was added to the reactor, heated to 110°C and stirred for 3 hours, and the stirred reaction product was distilled under reduced pressure to obtain modified vinyl silane.

[0058] 3. Preparation of base pellets: 100 parts by weight of polyolefin resin, 23 parts by weight of magnetic magnesium hydroxide flame retardant, 2.8 parts by weight of modified vinyl silane, 1.2 parts by weight of dicumyl peroxide, and 0.8 parts by weight of ethyl dimethylaminobenzoate were stirred and blended. The blended material was electromagnetically stirred at a speed of 500 rpm for 35 minutes. The electromagnetically stirred blended material was extruded and granulated. An ordered magnetic field was set on the extrusion molding path in the same direction as the extrusion molding. The ordered magnetic field controlled the distribution of the magnetic metal hydroxide flame retardant in the molding material. The magnetic field strength of the ordered magnetic field was 1200 mT. The ordered magnetic field covered the feeding section, compression section, homogenization section, and extrusion die section of the extrusion molding. The temperature of the feeding section was 135-150°C, the temperature of the compression section was 155-162°C, the temperature of the homogenization section was 145-158°C, and the temperature of the extrusion die section was 135-160°C.

[0059] 4. Preparation of catalytic pellets: 100 parts by weight of polyolefin resin and 0.8 parts by weight of dibutyltin dilaurate were uniformly mixed, and catalytic pellets were prepared by extrusion melt granulation.

[0060] 5. Preparation of room temperature self-crosslinking flame retardant insulating material: According to the ratio of parts by weight, 100 parts by weight of base pellets and 9 parts by weight of catalytic pellets are uniformly blended, and the blended pellets are extruded. The temperature of the feeding section of the extrusion molding is 120-150°C, the temperature of the compression section is 155-182°C, the temperature of the homogenization section is 145-175°C, and the temperature of the extrusion die section is 125-165°C. After standing at room temperature for 28 hours, the room temperature self-crosslinking flame retardant insulating material is obtained.

[0061] Example 6 Preparation method of room temperature self-crosslinking flame retardant insulation material of Example 3 of the present application: 1. Preparation of magnetic magnesium hydroxide flame retardant: 0.5 mol / L magnesium nitrate hexahydrate solution and 0.02 mol / L ferrosoferric oxide nanoparticle dispersion were prepared respectively, and the ferrosoferric oxide nanoparticle dispersion was mixed with the magnesium nitrate hexahydrate solution at a volume ratio of 1:2 to form a mixed solution, and the pH value of the mixed solution was adjusted to 5. A 25% by mass ammonia aqueous solution was added to the mixed solution, and the pH value of the solution system was adjusted to 9. After standing for 20 hours, a mixed gel was obtained. The mixed gel was washed and dried at 85°C for 3 hours. The dried gel powder was ball-milled at 400 rpm to obtain a magnetic magnesium hydroxide flame retardant with an average particle size of 150 nm.

[0062] 2. Preparation of modified vinyl silane: 30 parts by weight of dimethylsiloxane ring, 2 parts by weight of potassium hydroxide and 20 parts by weight of ethanol were added to a reactor, heated to 80°C and stirred for 30 minutes, 5 parts by weight of vinyl silane was added to the reactor, heated to 110°C and stirred for 3 hours, and the stirred reaction product was distilled under reduced pressure to obtain modified vinyl silane.

[0063] 3. Preparation of base pellets: 100 parts by weight of polyolefin resin, 25 parts by weight of magnetic magnesium hydroxide flame retardant, 2.8 parts by weight of modified vinyl silane, 1.2 parts by weight of dicumyl peroxide, and 0.8 parts by weight of ethyl dimethylaminobenzoate were stirred and blended. The blended material was electromagnetically stirred at a speed of 500 rpm for 35 minutes. The electromagnetically stirred blended material was extruded and granulated. An ordered magnetic field was set on the extrusion molding path in the same direction as the extrusion molding direction. The ordered magnetic field controlled the distribution of the magnetic metal hydroxide flame retardant in the molding material. The magnetic field strength of the ordered magnetic field was 1200 mT. The ordered magnetic field covered the feeding section, compression section, homogenization section, and extrusion die section of the extrusion molding. The temperature of the feeding section was 135-150°C, the temperature of the compression section was 155-162°C, the temperature of the homogenization section was 145-158°C, and the temperature of the extrusion die section was 135-160°C.

[0064] 4. Preparation of catalytic pellets: 100 parts by weight of polyolefin resin and 0.8 parts by weight of dibutyltin dilaurate were uniformly mixed, and catalytic pellets were prepared by extrusion melt granulation.

[0065] 5. Preparation of room temperature self-crosslinking flame retardant insulating material: According to the ratio of parts by weight, 100 parts by weight of base pellets and 11 parts by weight of catalytic pellets are uniformly blended, and the blended pellets are extruded. The temperature of the feeding section of the extrusion molding is 120-150°C, the temperature of the compression section is 155-182°C, the temperature of the homogenization section is 145-175°C, and the temperature of the extrusion die section is 125-165°C. After standing at room temperature for 28 hours, the room temperature self-crosslinking flame retardant insulating material is obtained.

[0066] Example 7 The morphology of the gel powder and the magnetic magnesium hydroxide flame retardant prepared in Example 2 of the present application was observed using a Zeiss Ultra Plus scanning electron microscope. The test acceleration voltage was 10 kV-30 kV. Figure 2 This is a SEM morphology of the gel powder prepared according to Example 2 of the present application, as shown in FIG. Figure 2 As shown, the gel powder prepared by the sol-gel method in Example 2 of the present application includes magnesium hydroxide powder and ferroferric oxide nanoparticles dispersed in the magnesium hydroxide powder. Before ball milling, the magnesium hydroxide powder and the ferroferric oxide nanoparticles are clustered to varying degrees. Figure 3 This is an SEM morphology of the magnetic magnesium hydroxide flame retardant prepared according to Example 2 of the present application, as shown in FIG. Figure 3 As shown, in this embodiment, the gel powder is further processed by ball milling. After the ball milling, the magnesium hydroxide and ferrosoferric oxide nanoparticles in the gel powder are more evenly distributed, the clusters disappear, and the average particle size of the magnetic magnesium hydroxide flame retardant is 150 nm.

[0067] The phase of the magnetic magnesium hydroxide flame retardant prepared in Example 3 of the present application was detected using a Bruker D8 Advance X-ray diffractometer with a test detection voltage of 40 kV, a test detection current of 40 mA, a test scanning speed of 5° / min, and a scanning step of 0.02°. Figure 4 This is an example diagram of the XRD phase attribution of the magnetic magnesium hydroxide flame retardant prepared according to Example 3 of the present application. In the figure, is the angle between the incident X-ray and the diffracted X-ray, hkl is the crystal plane index, and d is the interplanar spacing. Figure 5 This is a key peak marker diagram of the magnetic magnesium hydroxide flame retardant prepared according to Example 3 of the present application. Figure 4 and Figure 5As shown in the figure, in the 18.3°-18.5° region, the peaks of Fe3O4(111) and Mg(OH)2(001) overlap, which is a broadened peak. At 35.4°, the relative intensity is 1200, corresponding to the strongest peak of Fe3O4(311). In the 38°-43° region, the peaks of Mg(OH)2 (101) and Fe3O4 (400) are separated. In the 50.8°-53.4° region, the peak positions of the two are close and partially overlap. This indicates that the magnetic magnesium hydroxide flame retardant implemented in this application contains magnesium hydroxide and ferrosoferric oxide, and the ferrosoferric oxide is relatively evenly distributed in the magnesium hydroxide.

[0068] Example 8 According to the performance requirements of halogen-free, low-smoke, flame-retardant cross-linked polyolefin insulation materials in GB / T 32129 Halogen-free, low-smoke, flame-retardant cable materials for wires and cables, the base pellets prepared in Examples 2 to 6 of the present application were tested. The test results are shown in Table 1 below.

[0069] Table 1

[0070] As can be seen from Table 1, the volume resistivity of the base granules prepared in the embodiment of the present application at 20°C is not less than 1.1×10 12 Ω·m, volume resistivity at 150℃ is not less than 2.8×10 11 Ω·m, dielectric strength is not less than 25MV / m, oxygen index is not less than 32%, and smoke density is not greater than 31 under flame conditions, indicating that the material has excellent insulating electrical properties and flame retardant properties.

[0071] According to the non-electrical requirements for halogen-free and low-smoke cross-linked polyolefin insulation in "JB / T 10491-2022 Cross-linked Polyolefin Insulated Wires and Cables with Rated Voltages of 450 / 750V and Below", the room temperature self-cross-linking flame-retardant insulating materials prepared in Examples 2 to 6 of the present application were tested. The test results are shown in Table 2 below.

[0072] Table 2

[0073] As shown in Table 2, the room-temperature self-crosslinking flame-retardant insulation material prepared in the examples of the present application has a tensile strength of no less than 15.6 MPa and an elongation at break of no less than 170%. Its elongation at 200°C and 0.2 MPa load is no more than 25%, and its elongation after cooling from the hot extension is no more than 15%. Its thermal shrinkage at 180°C is less than 1%, it exhibits no cracking in a low-temperature bending test at -20°C, and its elongation at -20°C is no less than 130%. This demonstrates the material's excellent mechanical and physical properties, as well as its environmental performance.

[0074] The base granules prepared in Examples 2 to 6 of this application were blended with catalytic granules, respectively. The blended granules were then coated on the outside of the conductor by extrusion molding. After standing at room temperature for 28 hours, room-temperature self-crosslinking flame-retardant insulated cables were produced, numbered A1 to A5. The resulting room-temperature self-crosslinking flame-retardant insulated cables were subjected to a combustion test in accordance with GB / T 18380.12-2022: Fire tests for electrical and optical cables under flame conditions - Part 12: Single insulated wire and cable vertical flame spread test - 1kW premixed flame test method. All samples A1 to A5 passed the combustion test, demonstrating that the room-temperature self-crosslinking flame-retardant insulation materials prepared in the examples of this application have excellent flame retardant properties.

[0075] The room temperature self-crosslinking flame-retardant insulated cable and its preparation method according to the embodiments of the present application have the following beneficial technical effects: 1. Improve flame retardant properties 1. Uniform distribution of flame retardants: By using magnetic metal hydroxide flame retardants and combining them with an ordered magnetic field to control their distribution in the molding material, a uniform and orderly distribution of the flame retardant in the polymer matrix is ​​achieved. This uniform distribution avoids the problem of local flame retardant failure caused by uneven distribution of flame retardants in the existing technology, thereby significantly improving the overall flame retardant properties of the material.

[0076] 2. Reduce the amount of flame retardant used: On the basis of achieving uniform distribution, the amount of flame retardant used is reduced. Compared with the traditional technology that requires excessive addition of flame retardant to compensate for the lack of uneven distribution, the present invention reduces the proportion of flame retardant while improving the flame retardant performance, thereby reducing the adverse effects on the insulating electrical properties and mechanical properties of the base polymer material.

[0077] 3. Meet high-standard flame retardant requirements: After testing, the room-temperature self-crosslinking flame-retardant insulation material prepared by the present invention has an oxygen index of not less than 32%, and a smoke density of not more than 31 under flame conditions. The prepared cable has passed the "GB / T 18380.12-2022" single insulated wire and cable flame vertical spread test, indicating that its flame retardant performance meets high-standard requirements.

[0078] 2. Optimizing cross-linking efficiency and cost 1. Submit crosslinking quality: This invention utilizes a grafting reaction and condensation reaction between modified vinyl silane and polyolefin to achieve room-temperature self-crosslinking. Compared to traditional chemical crosslinking (such as silane warm water crosslinking and silane steam crosslinking), it does not require high temperatures and steam environments, thus avoiding the problems of incomplete or excessive crosslinking caused by improper temperature and time control. Compared to physical crosslinking (such as electron irradiation crosslinking and UV light crosslinking), it does not require specialized equipment, reduces the requirements for the operating environment and personnel protection, and significantly reduces crosslinking costs.

[0079] 2. Improved cross-linking efficiency: Room temperature self-cross-linking technology allows the material to complete cross-linking even when left at room temperature, significantly shortening the cross-linking time and improving production efficiency. In this invention, cross-linking is completed after just 40 hours of standing at room temperature, whereas traditional cross-linking methods may require longer time and more complex process conditions.

[0080] 3. Improved process adaptability: The cross-linking method of the present invention has low dependence on environmental conditions and can be stably carried out under a wider range of environmental conditions, thereby improving the adaptability and controllability of the production process and being more suitable for large-scale industrial production.

[0081] 3. Optimize mechanical properties and insulation properties 1. Improved Mechanical Properties: By optimizing the distribution and crosslinking of the flame retardant, this invention reduces the amount of flame retardant used while better preserving the original mechanical properties of the polyolefin resin. Furthermore, the grafting of modified vinyl silane further enhances the material's mechanical properties, achieving a tensile strength of no less than 15.6 MPa and an elongation at break of no less than 170%.

[0082] 2. Maintaining insulation electrical properties: While improving flame retardancy and mechanical properties, the material of the present invention still maintains excellent insulation electrical properties with a volume resistivity of not less than 1.1×10 12 Ω·m, volume resistivity at 150℃ is not less than 2.8×10 11 Ω·m, and the dielectric strength is not less than 25MV / m, which meets the high requirements of insulation performance for wire and cable insulation materials.

[0083] 3. Balanced Comprehensive Performance: This invention achieves a good balance between flame retardancy, mechanical properties, and insulation electrical properties. Compared to existing technologies that struggle to balance flame retardancy, mechanical properties, and processing performance, this invention achieves a better balance across multiple performance indicators by optimizing the material formulation and preparation process, making it more suitable for use in the field of wire and cable insulation materials with high performance requirements.

[0084] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing a room temperature self-crosslinking flame retardant insulating material, characterized in that: The method comprises: preparing a magnetic metal hydroxide flame retardant by a sol-gel method, preparing a modified vinyl silane by a ring-opening polymerization reaction; carrying out orderly grafting and granulation of a polyolefin resin, a magnetic metal hydroxide flame retardant and a modified vinyl silane to prepare a base granule; blending the base granule with a catalytic granule, extruding the blended granule into shape, and allowing the blended granule to stand at room temperature to prepare a room temperature self-crosslinking flame retardant insulating material.

2. The method for preparing a room temperature self-crosslinking flame retardant insulating material according to claim 1, characterized in that: A magnetic metal hydroxide flame retardant is prepared by a sol-gel method, comprising: dispersing magnetic metal oxide nanoparticles in a magnesium nitrate hexahydrate solution to form a mixed solution, hydrolyzing the mixed solution under alkaline conditions to form a mixed gel, and washing, drying and ball-milling the mixed gel to obtain the magnetic metal hydroxide flame retardant.

3. The method for preparing a room temperature self-crosslinking flame retardant insulating material according to claim 2, characterized in that: A magnetic metal hydroxide flame retardant is prepared by a sol-gel method, comprising: separately preparing a 0.5 mol / L magnesium nitrate hexahydrate solution and a 0.02 mol / L ferroferric oxide nanoparticle dispersion, mixing the ferroferric oxide nanoparticle dispersion into the magnesium nitrate hexahydrate solution at a volume ratio of 1:2 to form a mixed solution, adjusting the pH value of the mixed solution to 5, adding a 25% by mass ammonia aqueous solution to the mixed solution, adjusting the pH value of the solution system to 9, standing the solution for 20 hours to obtain a mixed gel, washing the mixed gel and drying it at 85°C for 3 hours, and ball milling the dried gel powder at 400 rpm to prepare the magnetic magnesium hydroxide flame retardant.

4. The method for preparing a room temperature self-crosslinking flame retardant insulating material according to claim 1, characterized in that: The modified vinyl silane is prepared by a ring-opening polymerization reaction, comprising: adding 30 parts by weight of a dimethylsiloxane ring, 2 parts by weight of potassium hydroxide, and 20 parts by weight of ethanol into a reactor, heating the reaction mixture to 80° C. and stirring for 30 minutes, adding 5 parts by weight of vinyl silane into the reactor, heating the reaction mixture to 110° C. and stirring the reaction mixture for 3 hours, and performing reduced pressure distillation on the stirred reaction product to obtain the modified vinyl silane.

5. The method for preparing a room temperature self-crosslinking flame retardant insulating material according to claim 1, characterized in that: Polyolefin resin, magnetic metal hydroxide flame retardant and modified vinyl silane are subjected to orderly grafting and granulation to prepare base granules, comprising: stirring and blending polyolefin resin, magnetic magnesium hydroxide flame retardant, modified vinyl silane, dicumyl peroxide and ethyl dimethylaminobenzoate in parts by weight, subjecting the blended material to electromagnetic stirring, extruding and granulating the electromagnetically stirred blended material, and providing an ordered magnetic field consistent with the extrusion direction on the extrusion molding path to control the distribution of the magnetic metal hydroxide flame retardant in the molding material through the ordered magnetic field.

6. The method for preparing a room temperature self-crosslinking flame retardant insulating material according to claim 5, characterized in that: 100 parts by weight of polyolefin resin, 18-25 parts by weight of magnetic magnesium hydroxide flame retardant, 2.8 parts by weight of modified vinyl silane, 1.2 parts by weight of dicumyl peroxide and 0.8 parts by weight of ethyl dimethylaminobenzoate were stirred and blended at a speed of 500 rpm and a time of 35 min.

7. The method for preparing a room temperature self-crosslinking flame retardant insulating material according to claim 5, characterized in that: The magnetic field strength of the ordered magnetic field is 1200mT. The range of the ordered magnetic field covers the feeding section, compression section, homogenization section and extrusion die section of extrusion molding. The temperature of the feeding section is 135-150℃, the temperature of the compression section is 155-162℃, the temperature of the homogenization section is 145-158℃, and the temperature of the extrusion die section is 135-160℃.

8. The method for preparing a room temperature self-crosslinking flame retardant insulating material according to claim 1, characterized in that: The catalytic pellets are prepared by extrusion melt granulation of 100 parts by weight of polyolefin resin and 0.8 parts by weight of dibutyltin dilaurate.

9. The method for preparing a room temperature self-crosslinking flame retardant insulating material according to claim 8, characterized in that: According to the ratio of parts by weight, 100 parts by weight of base granules and 5.5-11 parts by weight of catalytic granules are uniformly blended, and the blended granules are extruded. The temperature of the feeding section of the extrusion molding is 120-150°C, the temperature of the compression section is 155-182°C, the temperature of the homogenization section is 145-175°C, the temperature of the extrusion die section is 125-165°C, and the room temperature self-crosslinking flame retardant insulating material is obtained after standing at room temperature for 28 hours.

10. A room temperature self-crosslinking flame retardant insulating material, characterized in that: The room temperature self-crosslinking flame retardant insulating material is prepared according to any one of claims 1 to 9.

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