Semi-conductive PVC cable material and preparation method thereof

Abstract

The invention discloses a semi-conductive PVC (polyvinyl chloride) cable material and a preparation method thereof. The cable material is prepared from the following raw materials: 66 to 85 parts of PVC resin with the polymerization degree of 1300, 38 to 45 parts of di (2-propylheptyl) phthalate, 3 to 4 parts of dioctyl sebacate, 3 to 4 parts of epoxidized soybean oil, 9.5 to 23.5 parts of conductive agent, 5.4 to 6.2 parts of calcium-zinc heat stabilizer, 0.2 to 0.35 part of antioxidant, 0.35 to 0.5 part of lubricant, 1.4 to 1.7 parts of processing modifier P551J and 3 to 4 parts of chlorinated polyethylene CPE. The cable material disclosed by the invention not only has excellent conductivity and can meet basic requirements of high-voltage cables, but also can keep a stable physical state in a low-temperature environment without embrittlement or performance reduction, shows excellent mechanical strength under the action of external force, and ensures the integrity of a cable structure and the reliability of long-term operation.

Description

Technical Field

[0001] The invention relates to the field of cable materials, and in particular to a semi-conductive PVC cable material and a preparation method thereof. Background Art

[0002] In the power transmission and distribution system, high-voltage cables play a vital role, and their performance directly affects the stability and safety of the power system. However, traditional semi-conductive polyvinyl chloride (PVC) cable materials face a major challenge in the field of materials science: due to the introduction of a large amount of conductive materials in the formula, although the necessary conductivity is achieved, its low-temperature resistance and mechanical strength are inevitably sacrificed. This defect is like a shackle that tightly constrains the further development of high-voltage cable technology and limits their application potential under extreme environmental conditions, especially in cold regions or in situations where they need to withstand high-intensity mechanical stress.

[0003] Faced with this technical bottleneck, researchers and material engineers are in urgent need of exploring an innovative solution to break the limitations of traditional materials and promote the innovation of high-voltage cable technology. Through in-depth research and practice, the rational optimization of the formula structure of cable materials has become a breakthrough. The core of this effort is how to maintain the low volume resistivity of the material, that is, maintain good electrical conductivity, while significantly improving its low temperature resistance and mechanical properties, achieving a perfect balance between the three.

[0004] Therefore, a new type of semi-conductive PVC cable material is developed, which not only has excellent conductivity to meet the basic needs of high-voltage cables, but also can maintain a stable physical state in low-temperature environments without embrittlement or performance degradation, and at the same time exhibits excellent mechanical strength when subjected to external forces, ensuring the integrity of the cable structure and long-term reliability. The realization of this goal will not only inject new vitality into the high-voltage cable industry, but will also promote the entire power industry to develop in a more efficient, safer and more environmentally friendly direction, which has far-reaching practical significance and social value. Summary of the invention

[0005] The purpose of the present invention is to provide a semi-conductive PVC cable material and a preparation method thereof.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A semi-conductive PVC cable material, the raw materials of which include the following components in parts by weight:

[0008]

[0009]

[0010] In the above scheme, PVC resin with a degree of polymerization of 1300, di(2-propylheptyl)phthalate, dioctyl sebacate, calcium zinc heat stabilizer, and conductive agent are core components.

[0011] Type 1300 PVC resin powder is the base material of semi-conductive PVC cable material. Di(2-propylheptyl)phthalate and dioctyl sebacate plasticizers give PVC resin good flexibility and low temperature resistance. Calcium zinc heat stabilizer ensures the stability of PVC under heat and shear force, avoiding product deterioration due to PVC degradation. When the conductive agent reaches a certain concentration, a conductive network will be formed inside the material, greatly reducing the volume resistivity and giving the thermoplastic PVC mixture good conductive properties.

[0012] According to a further technical solution, the lubricant is selected from at least one of stearic acid, polyethylene wax, calcium stearate and zinc stearate.

[0013] In a further technical solution, the antioxidant is selected from at least one of tris[2,4-di-tert-butylphenyl]phosphite, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid octadecanoate.

[0014] In a further technical solution, the conductive agent is one or a mixture of conductive carbon black type B, conductive carbon black 3650, and carbon nanotubes.

[0015] The present invention further discloses a method for preparing a semi-conductive PVC cable material, comprising:

[0016] Step 1, under the condition that the kneading machine speed is 700-780rpm, 66-85 parts of PVC resin powder with a polymerization degree of 1300 are added; under the condition that the kneading machine speed is 720-780rpm, 38-45 parts of di(2-propylheptyl)phthalate, 3-4 parts of dioctyl sebacate, 3-4 parts of epoxy soybean oil, and 5.4-6.2 parts of calcium zinc heat stabilizer are added, and kneading is carried out for 4-6 minutes, and the kneading temperature is controlled at 80-90°C;

[0017] Step 2: Under the condition that the kneading machine speed is 720-780 rpm, 0.35-0.5 parts of lubricant, 0.2-0.35 parts of antioxidant, 1.4-1.7 parts of processing modifier P551J, 3-4 parts of chlorinated polyethylene CPE, and 9.5-23.5 parts of conductive agent are added, and then kneading is continued for 3-5 minutes, and the kneading temperature is controlled at 120-130°C;

[0018] Step 3: Stir at a high speed at a kneading machine speed of 1450-1500 rpm, then reduce the speed to 700-780 rpm, knead for 3-5 minutes, the material temperature is 125-135°C, mix thoroughly and evenly, and then discharge;

[0019] Step 4: Use a co-rotating twin-screw extruder unit for extrusion mixing and plasticization, the setting temperature range of the twin-screw extruder is 155-175°C, and the frequency is 18-40Hz; the setting temperature range of the single-screw extruder is 150-165°C, and the frequency is 16-35Hz;

[0022] Step 5: Cool and sieve to obtain the semi-conductive PVC cable material.

[0023] In a further technical solution, the co-rotating twin-screw extruder is a SDJ 75-180-two-stage co-rotating twin-screw extruder. The twin screws efficiently shear and plasticize the material, which is conducive to the good dispersion of the conductive agent; the single screw has low speed and low shear, and the granulation process avoids overheating and degradation of the PVC material.

[0024] The terms “include,” “including,” “have,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0025] The terms used herein generally have the ordinary meanings of each term used in the art, in the context of the present invention, and in the specific context, unless otherwise noted. Certain terms used to describe the present invention will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art regarding the description of the present invention.

[0026] The working principle and advantages of the present invention are as follows:

[0027] 1. The present invention forms a conductive network structure inside the thermoplastic PVC mixture by adding a conductive agent (such as conductive carbon black and / or carbon nanotubes) when the local conductive fillers are in direct contact or the spacing is very small (<1nm). Under the action of an external electric field, electrons move through the conductive network inside the PVC to form a channel current. Tests show that the volume resistivity of the material is less than 100Ω·cm, with a typical value of 39Ω·cm. It has excellent conductive properties and can replace graphite coatings for high-voltage cables, with broad application prospects.

[0028] 2. The dioctyl sebacate added in the present invention belongs to aliphatic dibasic acid plasticizers, and its molecular structure has a relatively long fat chain. Even at low temperatures, it can still maintain the movement between polymer molecular chains, thereby maintaining the flexibility of the material. Adding a proper amount can make the cold resistance level of PVC products reach -26 to 40°C; chlorinated polyethylene itself is rubber, which can provide better elasticity for PVC materials, thereby also playing a toughening role and achieving a certain cold resistance effect.

[0029] 3. The present invention has excellent processing performance, simple process, high production efficiency and can be industrialized on a large scale. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with embodiments:

[0031] The present invention will be described in detail below. After understanding the embodiments of the present invention, any person skilled in the art can make changes and modifications based on the techniques taught by the present invention without departing from the spirit and scope of the present invention.

[0032] The terms used herein are only for describing specific embodiments and are not intended to be limiting of the present invention. Singular forms such as "a", "this", "here", "this" and "the" as used herein also include plural forms.

[0033] Embodiments 1 to 5: A semi-conductive PVC cable material, the components in parts by weight are shown in Table 1:

[0034] Table 1

[0035] Components Example 1 Example 2 Example 3 Example 4 Example 5 PVC resin with a degree of polymerization of 1300 66 copies 75 servings 75 servings 75 servings 85 copies Di(2-propylheptyl)phthalate 38 servings 41.5 servings 41.5 servings 41.5 servings 45 servings Dioctyl Sebacate 3 servings 3.5 servings 3.5 servings 3.5 servings 4 servings Epoxidized soybean oil 3 servings 3.5 servings 3.5 servings 3.5 servings 4 servings Calcium zinc heat stabilizer 5.4 servings 6 servings 6 servings 6 servings 6.2 servings Lubricants 0.35 0.4 parts 0.4 parts 0.4 parts 0.5 serving Processing modifier P551J 1.4 servings 1.5 servings 1.5 servings 1.5 servings 1.7 servings Antioxidants 0.2 parts 0.3 parts 0.3 parts 0.3 parts 0.35 Chlorinated Polyethylene CPE 3 servings 3.5 servings 3.5 servings 3.5 servings 4 servings Conductive carbon black type B 0 copies 0 copies 5 servings 10 servings 11.5 servings Conductive carbon black 3650 0 copies 0 copies 7 servings 12 servings 12 servings Carbon Nanotubes 9.5 servings 11.5 servings 5 servings 0 copies 0 copies

[0036] The lubricant of Example 1 is calcium stearate, the lubricant of Example 2 is stearic acid, the lubricant of Example 3 is a mixture of polyethylene wax and zinc stearate in a mass ratio of 1:1, the lubricant of Example 4 is a mixture of polyethylene wax and calcium stearate in a mass ratio of 1:1, and the lubricant of Example 5 is a mixture of stearic acid and zinc stearate in a mass ratio of 1:1.

[0037] The antioxidant of Example 1 is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], the antioxidant of Example 2 is tris[2,4-di-tert-butylphenyl]phosphite, the antioxidant of Example 3 is β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecanoate, the antioxidant of Example 4 is a mixture of tris[2,4-di-tert-butylphenyl]phosphite and β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecanoate, the mass ratio of which is 2:1, and the antioxidant of Example 5 is a mixture of tris[2,4-di-tert-butylphenyl]phosphite and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], the mass ratio of which is 3:4.

[0038] The calcium zinc heat stabilizer used in Examples 1 and 2 is the German Bear brand environmentally friendly calcium zinc composite stabilizer MC 9700KA / 1; the calcium zinc heat stabilizer used in Examples 3 and 4 is the Austrian Kemissen PKD 1930 environmentally friendly calcium zinc stabilizer; the calcium zinc heat stabilizer used in Example 5 is a mixture of MC 9700KA / 1 and PKD 1930, with a mass ratio of 1:1.

[0039] The above-mentioned processing modifier P551J is produced by Mitsubishi Corporation of Japan.

[0040] A method for preparing a semi-conductive PVC cable material comprises the following steps:

[0041] Step 1, under the condition that the kneading machine speed is 700-780rpm, 66-85 parts of PVC resin powder with a polymerization degree of 1300 are added; under the condition that the kneading machine speed is 720-780rpm, 38-45 parts of di(2-propylheptyl)phthalate, 3-4 parts of dioctyl sebacate, 3-4 parts of epoxy soybean oil, and 5.4-6.2 parts of calcium zinc heat stabilizer are added, and kneading is carried out for 4-6 minutes, and the kneading temperature is controlled at 80-90°C;

[0042] Step 2: Under the condition that the kneading machine speed is 720-780 rpm, 0.35-0.5 parts of lubricant, 0.2-0.35 parts of antioxidant, 1.4-1.7 parts of processing modifier P551J, 3-4 parts of chlorinated polyethylene CPE, and 9.5-23.5 parts of conductive agent are added, and then kneading is continued for 3-5 minutes, and the kneading temperature is controlled at 120-130°C;

[0043] Step 3: Stir at a high speed at a kneading machine speed of 1450-1500 rpm, then reduce the speed to 700-780 rpm, knead for 3-5 minutes, the material temperature is 125-135°C, mix thoroughly and evenly, and then discharge;

[0044] Step 4: Use SDJ 75-180-two-stage co-rotating twin-screw extruder unit for extrusion mixing and plasticization. The setting temperature range of the twin-screw extruder is 155-175°C and the frequency is 18-40Hz; the setting temperature range of the single-screw extruder is 150-165°C and the frequency is 16-35Hz;

[0045] Step 5: Cool and sieve to obtain the semi-conductive PVC cable material.

[0046] The semi-conductive PVC cable material obtained in Examples 1, 2, 3, 4 and 5 of the present invention was tested, and the results were compared with those of Comparative Examples 1 to 2, as shown in Table 2:

[0047] Table 2

[0048]

[0049] The components of Comparative Example 1 and Comparative Example 2 are shown in Table 3:

[0050] Table 3

[0051]

[0052] The calcium zinc heat stabilizer of Comparative Example 1 is MC 9700KA / 1, and the lubricant is polyethylene wax.

[0053] In Comparative Example 2, the calcium zinc heat stabilizer is PKD 1930, the lubricant is stearic acid, and the antioxidant is tris[2,4-di-tert-butylphenyl]phosphite.

[0054] Since the amount of conductive filler added is controlled in Examples 1 to 5, a better balance is found between conductive properties, mechanical properties, and cold resistance. Carbon nanotubes or a mixture of carbon nanotubes / conductive carbon black are preferably introduced, so that good mechanical and cold resistance properties are achieved while maintaining a low volume resistivity. However, Comparative Examples 1 and 2 add a large amount of conductive filler, increase the stress concentration points, and do not add toughening materials, resulting in a decrease in mechanical properties and cold resistance. If such materials are used to make finished cables, there are certain risks. In summary, the semi-conductive PVC material produced by the present invention has good mechanical properties and conductivity by adding an appropriate amount of conductive carbon black or carbon nanotubes or a mixture of conductive carbon black and carbon nanotubes, and the added appropriate amount of cold-resistant plasticizer and toughening agent gives the material good cold resistance.

[0055] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A semi-conductive PVC cable material, characterized in that: The raw materials include the following components in parts by weight: 66~85 parts of PVC resin with a degree of polymerization of 1300, 38-45 parts of di(2-propylheptyl)phthalate, 3-4 parts of dioctyl sebacate, Epoxidized soybean oil 3~4 parts, Conductive agent 9.5~23.5 parts, Calcium zinc heat stabilizer 5.4~6.2 parts, Antioxidant 0.2~0.35 parts, Lubricant 0.35~0.5 parts, Processing modifier P551J 1.4~1.7 parts, Chlorinated polyethylene CPE 3~4 parts.

2. A semi-conductive PVC cable material according to claim 1, characterized in that: The lubricant is selected from at least one of stearic acid, polyethylene wax, calcium stearate and zinc stearate.

3. A semi-conductive PVC cable material according to claim 1, characterized in that: The antioxidant is selected from at least one of tris[2,4-di-tert-butylphenyl]phosphite, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

4. A semi-conductive PVC cable material according to claim 1, characterized in that: The conductive agent is one of conductive carbon black type B, conductive carbon black 3650, and carbon nanotubes, or a mixture of several of them.

5. A method for preparing a semi-conductive PVC cable material, characterized in that: Used to prepare the semi-conductive PVC cable material according to any one of claims 1 to 4, the preparation method comprising: Step 1: Under the condition that the kneading machine speed is 700-780rpm, 66-85 parts of PVC resin powder with a polymerization degree of 1300 are added; under the condition that the kneading machine speed is 720-780rpm, 38-45 parts of di(2-propylheptyl)phthalate, 3-4 parts of dioctyl sebacate, 3-4 parts of epoxy soybean oil, and 5.4-6.2 parts of calcium zinc heat stabilizer are added, and kneading is carried out for 4-6 minutes, and the kneading temperature is controlled at 80-90°C; Step 2: Under the condition that the kneading machine speed is 720-780 rpm, add 0.35-0.5 parts of lubricant, 0.2-0.35 parts of antioxidant, 1.4-1.7 parts of processing modifier P551J, 3-4 parts of chlorinated polyethylene CPE, and 9.5-23.5 parts of conductive agent, and then continue kneading for 3-5 minutes, and the kneading temperature is controlled at 120-130°C; Step 3: Stir at a high speed at a kneading machine speed of 1450-1500 rpm, then reduce the speed to 700-780 rpm, knead for 3-5 minutes, the material temperature is 125-135°C, mix thoroughly and evenly before discharging; Step 4: Use a co-rotating twin-screw extruder unit for extrusion mixing and plasticization, the setting temperature range of the twin-screw extruder is 155~175℃, and the frequency is 18~40 Hz; the setting temperature range of the single-screw extruder is 150~165℃, and the frequency is 16~35Hz; Step 5: Cool and sieve to obtain the semi-conductive PVC cable material.

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