Flame-resistant polyethylene wire cable and production method thereof

Abstract

The invention relates to the technical field of cables, and discloses a flame-resistant polyethylene wire and cable and a production method thereof.The wire and cable comprises a metal conductor and a polyethylene cable material wrapping the outer side of the metal conductor, and the polyethylene cable material takes high-density polyethylene and low-density polyethylene as main raw materials; according to the preparation method, a polyethylene matrix is used as a main material, an organic-inorganic composite flame retardant and other additives are used as auxiliary materials, mixing and extrusion processes are performed, the prepared organic-inorganic composite flame retardant is palygorskite of which the surface is coated with a phosphorus-containing polymeric macromolecular substance, and the organic phosphorus-containing polymeric macromolecular substance can form a'transition 'connection structure between the palygorskite and the polyethylene matrix; the transition structure can greatly improve the compatibility between the palygorskite and a polyethylene matrix, so that a mutual uniform dispersion effect can be generated between the palygorskite and the polyethylene matrix, and further the reinforcing effect of the organic-inorganic composite flame retardant can be utilized to improve the mechanical strength and flame resistance of the polyethylene.

Description

Technical Field

[0001] The invention relates to the technical field of cables, and in particular to a flame-resistant polyethylene electric wire and cable and a production method thereof. Background Art

[0002] As an indispensable basic material in modern power and communication networks, the quality and performance of wires and cables are directly related to the safe and stable operation of the entire system. Polyethylene (PE) is a lightweight, non-toxic thermoplastic with excellent electrical insulation and chemical corrosion resistance. Therefore, it is often used as a sheath material for wires and cables and has been widely used in the wire and cable industry. However, the flammability of polyethylene is a significant disadvantage. Especially under conditions of high voltage, heating, and discharge, polyethylene wires and cables are easy to burn, causing fires, threatening people's lives and property safety, and posing a great safety hazard. Therefore, it is particularly important to perform flame retardant modification on polyethylene wires and cables.

[0003] At present, the methods for flame retardant modification of polyethylene mainly include the following: first, by adding inorganic flame retardants, such as magnesium hydroxide, etc., because of the limited flame retardant modification effect of this type of flame retardant, it generally requires a larger addition amount to play a certain role, but the increase in the addition amount will also affect the mechanical strength and other properties of polyethylene. Secondly, by adding halogen or phosphorus flame retardants, the flame retardancy of polyethylene can also be improved, but halogen flame retardants are not environmentally friendly, and will generate toxic gases when burned, which poses a greater hidden danger. Conventional phosphorus flame retardants are easy to volatilize and migrate, and it is difficult to ensure the long-term flame retardancy of polyethylene. In summary, the existing technology for the flame retardant modification of polyethylene has certain defects. Based on this, the present invention provides a flame resistant polyethylene that can be used as a sheath material for wires and cables and can exhibit excellent flame retardant properties. Summary of the invention

[0004] 1. Technical issues to be solved

[0005] In view of the deficiencies in the prior art, the present invention provides a flame resistant polyethylene wire and cable and a production method thereof.

[0006] (II) Technical solution

[0007] A flame-resistant polyethylene wire and cable, comprising a metal conductor and a polyethylene cable material coated on the outside of the metal conductor; the polyethylene cable material comprises the following raw materials in parts by weight:

[0008]

[0009] The organic-inorganic composite flame retardant is palygorskite with phosphorus-containing polymer macromolecular substances coated on the surface.

[0010] As a further embodiment of the present invention, the compatibilizer is maleic anhydride grafted polyethylene or maleic anhydride grafted polypropylene.

[0011] As a further embodiment of the present invention, the preparation method of the organic-inorganic composite flame retardant comprises the following steps:

[0012] Step 1: using an epoxy silane coupling agent to modify the surface of palygorskite to obtain modified palygorskite;

[0013] Step 2: Using toluene as a dispersion medium, a phase transfer catalyst is used to catalyze the phosphorus-containing polymer macromolecular substance to further graft-modify the modified palygorskite, thereby obtaining an organic-inorganic composite flame retardant.

[0014] As a further embodiment of the present invention, in step 1, the epoxy silane coupling agent is γ-glycidyloxypropyltrimethoxysilane or γ-glycidyloxypropyltriethoxysilane.

[0015] As a further embodiment of the present invention, in step 2, the phase transfer catalyst is any one of tetrabutylammonium hydrogen sulfate, tetrabutylammonium bromide, tetramethylammonium bromide or tetrabutylammonium chloride.

[0016] As a further solution of the present invention, in step 2, the specific preparation method of the phosphorus-containing polymeric macromolecular substance comprises the following steps:

[0017] Step S1, nitrogen is charged into the reaction kettle, and then malic acid, 2-chloro-2-oxo-1,3,2-dioxaphospholane and tetrahydrofuran solvent are added into the reaction kettle, stirring is started, and after a uniform reaction liquid is formed, a basic catalyst is added into the reaction liquid, and after the addition is completed, heating is started, and the temperature is raised to 60-65° C., and the temperature is kept and stirred for 4-8 hours under this temperature condition, the solvent is evaporated and removed, and the product is collected by cooling to obtain a malic acid derivative;

[0018] Step S2, add malic acid derivatives and NN-dimethylformamide to the polymerization kettle, stir and mix, then add 2,6-pyridine dimethanol to the polymerization kettle, introduce nitrogen protection, and add p-toluenesulfonic acid at the same time. After the addition is completed, control the heating rate to 2-4°C / min, increase the temperature to 120-150°C, keep warm for 12-24h, cool and discharge, and obtain the phosphorus-containing polymer macromolecular substance.

[0019] As a further embodiment of the present invention, in step S1, the alkaline catalyst is triethylamine or pyridine.

[0020] As a further embodiment of the present invention, in step S2, the molar ratio of the malic acid derivative to 2,6-pyridine dimethanol is 1:0.8-1.

[0021] In the above technical scheme, malic acid and 2-chloro-2-oxo-1,3,2-dioxaphospholane are first used as reactants, and the active hydroxyl substituents and P-Cl between them are reacted under the catalysis of an alkaline catalyst to obtain a malic acid derivative containing a phosphorus flame retardant in its structure. Since its structure contains two equivalents of active carboxyl substituents, it can undergo continuous condensation reactions with the active hydroxyl substituents in the 2,6-pyridine dimethanol structure under the action of high temperature and p-toluenesulfonic acid to form a macromolecular alternating polymer connected by ester bonds, that is, a phosphorus-containing polymeric macromolecular substance.

[0022] Next, under the action of a phase transfer catalyst, the surface of the epoxidized palygorskite is further modified by using a phosphorus-containing polymer macromolecular substance to form a palygorskite with the surface coated with the phosphorus-containing polymer macromolecular substance, namely, an organic-inorganic composite flame retardant.

[0023] As a further embodiment of the present invention, the rubber-type additive is at least one of EPDM rubber, nitrile rubber or polybutadiene rubber; the antioxidant is antioxidant 1010 or antioxidant 168; the lubricant is at least one of polyethylene wax, stearic acid or paraffin; the inorganic filler is at least one of titanium dioxide, calcium titanate, talc or fumed silica.

[0024] A method for producing a flame-resistant polyethylene wire and cable comprises the following steps:

[0025] The first step: Preparation of polyethylene cable material

[0026] The raw materials are weighed and mixed according to the weight proportions, and then added into a mixer, mechanically stirred evenly at a temperature of 80-100°C, and then fed into a twin-screw extruder for melt extrusion to form a polyethylene cable material;

[0027] Step 2: Preparation of polyethylene wires and cables

[0028] Polyethylene cable is produced by extruding and coating the polyethylene cable material on the surface of the metal conductor, followed by cooling, winding and packaging.

[0029] (III) Beneficial technical effects

[0030] The organic-inorganic composite flame retardant prepared by the present invention is palygorskite with phosphorus-containing polymer macromolecules coated on the surface. First, the presence of organic phosphorus-containing polymer macromolecules is equivalent to forming a "transition" connection structure between palygorskite and polyethylene matrix. This transition structure can greatly improve the compatibility between palygorskite and polyethylene matrix, so that they can produce a mutually uniform dispersion effect, and then the reinforcing effect of palygorskite as an inorganic modifier can be used to improve the mechanical strength of polyethylene. Secondly, the structure of phosphorus-containing polymer macromolecules contains a large amount of nitrogen-phosphorus alternating flame retardant elements. These flame retardant elements can quickly form an expanded carbon layer during combustion to isolate oxygen and heat, thereby effectively improving the flame retardancy of polyethylene. In addition, palygorskite itself, as a magnesium-aluminum-rich mineral, can produce oxide isolation layers such as magnesium oxide and aluminum oxide in a high temperature environment. These oxides have a high melting point, good thermal stability, and a certain flame retardant effect, so that they can produce a synergistic effect with phosphorus-containing polymer macromolecules to jointly improve the flame retardancy of polyethylene. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below. 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 creative work.

[0032] Figure 1 This is the infrared analysis test diagram of phosphorus-containing polymeric macromolecules. DETAILED DESCRIPTION

[0033] In order to facilitate the understanding of the present invention, the present invention will be described more fully below. Preferred embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0034] Preparation Example

[0035] Preparation of organic-inorganic composite flame retardant:

[0036] Step 1, ultrasonically disperse 3.5 g of palygorskite in a 70% volume fraction ethanol solution, then add 5 g of γ-glycidyloxypropyltrimethoxysilane to the formed dispersion, after the addition, raise the temperature to 70° C., keep warm for 8 hours, separate the solid material, and obtain modified palygorskite;

[0037] Step 2: Add 2.6 g of modified palygorskite to toluene solvent and disperse for 40 minutes to form a uniform dispersion. Then, add 1.5 g of phosphorus-containing polymer macromolecular substance and 0.1 g of tetrabutylammonium bromide to the dispersion. After mechanical stirring, keep warm and stir at 75°C for 9 hours. Separate the solid material to obtain an organic-inorganic composite flame retardant.

[0038] The preparation method of the phosphorus-containing polymeric macromolecular substance comprises the following steps:

[0039] Step S1, nitrogen is charged into the reaction kettle, and then 0.8 g of malic acid, 0.85 g of 2-chloro-2-oxo-1,3,2-dioxaphospholane and tetrahydrofuran solvent are added into the reaction kettle, stirring is started, and after a uniform reaction liquid is formed, 0.1 g of triethylamine is added into the reaction liquid, and after the addition is completed, heating is started, and the temperature is raised to 65° C., and the temperature is kept and stirred for 6 hours under this temperature condition, the solvent is evaporated and removed, and the product is collected by cooling to obtain a malic acid derivative;

[0040] Step S2, add 1.2g of malic acid derivative and NN-dimethylformamide to the polymerization kettle, stir and mix, then add 0.6g of 2,6-pyridine dimethanol to the polymerization kettle, pass nitrogen protection, and add p-toluenesulfonic acid at the same time. After the addition, control the heating rate to 3°C / min, increase the temperature to 150°C, keep warm for 18h, cool and discharge, and the phosphorus-containing polymer macromolecular substance can be obtained.

[0041] Figure 1 This is the infrared analysis test chart of the phosphorus-containing polymer macromolecular substance, where 3000-3100cm -1 The characteristic absorption peak at 1700-1800 cm -1 The characteristic absorption peaks at 1264 cm -1 The characteristic absorption peak that appears at is the PO characteristic absorption peak.

[0042] Example 1

[0043] Preparation of polyethylene cable materials

[0044] According to weight proportions, 55 parts of high-density polyethylene, 15 parts of low-density polyethylene, 5 parts of maleic anhydride grafted polyethylene, 2 parts of organic-inorganic composite flame retardant, 5 parts of EPDM rubber, 0.5 parts of antioxidant 1010, 1 part of lubricant polyethylene wax, and 3 parts of inorganic filler titanium dioxide are weighed and mixed, then added into a mixer, mechanically stirred evenly at a temperature of 80°C, and then fed into a twin-screw extruder, the temperature is controlled at 240°C, the screw speed is controlled at 50rpm, and polyethylene cable material is formed through a melt extrusion process.

[0045] The preparation method of the organic-inorganic composite flame retardant is shown in the preparation example, and the same is true for the following.

[0046] Example 2

[0047] Preparation of polyethylene cable materials

[0048] According to weight proportions, 58 parts of high-density polyethylene, 18 parts of low-density polyethylene, 5 parts of maleic anhydride grafted polypropylene, 5 parts of organic-inorganic composite flame retardant, 10 parts of nitrile rubber, 0.6 parts of antioxidant 168, 1.5 parts of lubricant paraffin, and 5 parts of inorganic filler talc are weighed and mixed, then added into a mixer, mechanically stirred evenly at a temperature of 100°C, and then fed into a twin-screw extruder, the temperature is controlled at 240°C, the screw speed is 50rpm, and the polyethylene cable material is formed through a melt extrusion process.

[0049] Example 3

[0050] Preparation of polyethylene cable materials

[0051] According to weight proportions, 65 parts of high-density polyethylene, 25 parts of low-density polyethylene, 10 parts of maleic anhydride grafted polypropylene, 5.5 parts of organic-inorganic composite flame retardant, 15 parts of polybutadiene rubber, 1.5 parts of antioxidant 168, 2 parts of lubricant paraffin, and 6 parts of inorganic filler fumed silica are weighed and mixed, then added into a mixer, mechanically stirred evenly at a temperature of 100°C, and then fed into a twin-screw extruder, the temperature is controlled at 240°C, the screw speed is controlled at 50rpm, and the polyethylene cable material is formed through a melt extrusion process.

[0052] Comparative Example 1

[0053] Preparation of polyethylene cable materials

[0054] According to weight proportions, 58 parts of high-density polyethylene, 18 parts of low-density polyethylene, 5 parts of maleic anhydride grafted polypropylene, 5 parts of palygorskite, 10 parts of nitrile rubber, 0.6 parts of antioxidant 168, 1.5 parts of lubricant paraffin, and 5 parts of inorganic filler talc are weighed and mixed, then added into a mixer, mechanically stirred evenly at a temperature of 100°C, and then fed into a twin-screw extruder, the temperature is controlled at 240°C, the screw speed is controlled at 50rpm, and the polyethylene cable material is formed through a melt extrusion process.

[0055] Comparative Example 2

[0056] Preparation of polyethylene cable materials

[0057] According to weight proportions, 58 parts of high-density polyethylene, 18 parts of low-density polyethylene, 5 parts of maleic anhydride grafted polypropylene, 5 parts of phosphorus-containing polymer macromolecules, 10 parts of nitrile rubber, 0.6 parts of antioxidant 168, 1.5 parts of lubricant paraffin, and 5 parts of inorganic filler talc are weighed and mixed, then added into a mixer, mechanically stirred evenly at a temperature of 100°C, and then fed into a twin-screw extruder, the temperature is controlled at 240°C, the screw speed is controlled at 50rpm, and the polyethylene cable material is formed through a melt extrusion process.

[0058] The preparation method of the phosphorus-containing polymeric macromolecular substance is shown in the preparation example.

[0059] Comparative Example 3

[0060] Preparation of polyethylene cable materials

[0061] According to weight proportions, 58 parts of high-density polyethylene, 18 parts of low-density polyethylene, 5 parts of maleic anhydride grafted polypropylene, 10 parts of nitrile rubber, 0.6 parts of antioxidant 168, 1.5 parts of lubricant paraffin, and 5 parts of inorganic filler talc are weighed and mixed, then added into a mixer, mechanically stirred evenly at a temperature of 100°C, and then fed into a twin-screw extruder, the temperature is controlled at 240°C, the screw speed is controlled at 50rpm, and polyethylene cable material is formed through a melt extrusion process.

[0062] Test Case

[0063] The polyethylene cable materials in the embodiments and comparative examples were made into test samples and subjected to performance tests. The results are recorded in Table 1:

[0064] Table 1 - Performance test results

[0065] Tensile strength / MPa Limiting oxygen index / % Example 1 45.1 31.3 Example 2 45.3 31.6 Example 3 45.1 31.4 Comparative Example 1 39.4 23.9 Comparative Example 2 30.6 29.8 Comparative Example 3 29.8 18.2

[0066] The tensile strength test reference standard is GB / T 1040-2008; the limiting oxygen index test reference standard is GB / T2406-2009.

[0067] Analysis shows that the polyethylene cable material prepared by using the organic-inorganic composite flame retardant in the preparation example of the present invention as an additive has significantly better mechanical strength and excellent flame retardant properties. After the organic-inorganic composite flame retardant is replaced with unsurface-modified palygorskite, due to the interface problem between it and the matrix, it cannot fully exert the enhancement and modification effect, so the mechanical strength decreases. After the organic-inorganic composite flame retardant is replaced with a phosphorus-containing polymeric macromolecular substance, the enhancement and flame retardant effects of palygorskite are lost, resulting in a decrease in both the mechanical properties and flame retardant properties of the polyethylene cable material.

[0068] The specific preparation method of a flame-resistant polyethylene wire and cable prepared by using the polyethylene cable material in Example 2 of the present invention is as follows:

[0069] Polyethylene cable is produced by extruding and coating the polyethylene cable material on the surface of the metal conductor, followed by cooling, winding and packaging.

[0070] Based on the ideal embodiment of the present invention, through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A flame resistant polyethylene wire and cable, characterized in that: It comprises a metal conductor and a polyethylene cable material coated on the outside of the metal conductor; the polyethylene cable material comprises the following raw materials in parts by weight: The organic-inorganic composite flame retardant is palygorskite with phosphorus-containing polymer macromolecular substances coated on the surface.

2. A flame-resistant polyethylene wire and cable according to claim 1, characterized in that: The compatibilizer is maleic anhydride grafted polyethylene or maleic anhydride grafted polypropylene.

3. A flame resistant polyethylene wire and cable according to claim 1, characterized in that: The preparation method of the organic-inorganic composite flame retardant comprises the following steps: Step 1: using an epoxy silane coupling agent to modify the surface of palygorskite to obtain modified palygorskite; Step 2: Using toluene as a dispersion medium, a phase transfer catalyst is used to catalyze the phosphorus-containing polymer macromolecular substance to further graft-modify the modified palygorskite, thereby obtaining an organic-inorganic composite flame retardant.

4. A flame-resistant polyethylene wire and cable according to claim 3, characterized in that: In step 1, the epoxy silane coupling agent is γ-glycidyloxypropyltrimethoxysilane or γ-glycidyloxypropyltriethoxysilane.

5. A flame-resistant polyethylene wire and cable according to claim 3, characterized in that: In step 2, the phase transfer catalyst is any one of tetrabutylammonium hydrogen sulfate, tetrabutylammonium bromide, tetramethylammonium bromide or tetrabutylammonium chloride.

6. A flame resistant polyethylene wire and cable according to claim 3, characterized in that: In step 2, the specific preparation method of the phosphorus-containing polymeric macromolecular substance comprises the following steps: Step S1, nitrogen is charged into the reaction kettle, and then malic acid, 2-chloro-2-oxo-1,3,2-dioxaphospholane and tetrahydrofuran solvent are added into the reaction kettle, stirring is started, and after a uniform reaction liquid is formed, a basic catalyst is added into the reaction liquid, and after the addition is completed, heating is started, and the temperature is raised to 60-65° C., and the temperature is kept and stirred for 4-8 hours under this temperature condition, the solvent is evaporated and removed, and the product is collected by cooling to obtain a malic acid derivative; Step S2, add malic acid derivatives and NN-dimethylformamide to the polymerization kettle, stir and mix, then add 2,6-pyridine dimethanol to the polymerization kettle, introduce nitrogen protection, and add p-toluenesulfonic acid at the same time. After the addition is completed, control the heating rate to 2-4°C / min, increase the temperature to 120-150°C, keep warm for 12-24h, cool and discharge, and obtain the phosphorus-containing polymer macromolecular substance.

7. A flame-resistant polyethylene wire and cable according to claim 6, characterized in that: In step S1, the alkaline catalyst is triethylamine or pyridine.

8. A flame resistant polyethylene wire and cable according to claim 6, characterized in that: In step S2, the molar ratio of the malic acid derivative to 2,6-pyridine dimethanol is 1:0.8-1.

9. The flame-resistant polyethylene wire and cable according to claim 1, characterized in that: The rubber-type additive is at least one of EPDM rubber, nitrile rubber or polybutadiene rubber; the antioxidant is antioxidant 1010 or antioxidant 168; the lubricant is at least one of polyethylene wax, stearic acid or paraffin; the inorganic filler is at least one of titanium dioxide, calcium titanate, talc or fumed silica.

10. A method for producing a flame-resistant polyethylene wire and cable as claimed in claim 1, characterized in that: The following steps are involved: The first step: Preparation of polyethylene cable material The raw materials are weighed and mixed according to the weight proportions, and then added into a mixer, mechanically stirred evenly at a temperature of 80-100°C, and then fed into a twin-screw extruder for melt extrusion to form a polyethylene cable material; Step 2: Preparation of polyethylene wires and cables Polyethylene wires and cables can be produced by extruding polyethylene cable material and coating it on the surface of a metal conductor, followed by cooling, winding and packaging.

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