阅读说明：本技术 自限温伴热带电缆的制备方法 (Preparation method of self-temperature-limiting heat tracing belt cable ) 是由 张忠江 张晓军 赵爱媛 于 2019-08-20 设计创作，主要内容包括：本发明公开了自限温伴热带电缆的制备方法,属于电缆制备领域,自限温伴热带电缆的制备方法,包括以下步骤：步骤一、PTC复合材料的制备；步骤二、充分混合；步骤三、冷却挤出；步骤四、绝缘层包覆；步骤五、辐照交联；步骤六、编织屏蔽层；步骤七、挤包保护套；步骤八、检测、包装。本发明制备自限温伴热带电缆时,使用的PCT复合材料配方合理,由于添加了双组份热塑性聚合物,PCT复合材料之间组成一个稳定体系,在性能上优势互补,具有良好的电阻再现性和稳定性,同时又可大幅降低价格,降低了生产成本,本发明制备的自限温伴热电缆在长时间高温放置后仍具有高的电气性能的稳定特性,延长了自限温伴热电缆的使用寿命。(The invention discloses a preparation method of a self-temperature-limiting heat tracing belt cable, belonging to the field of cable preparation, and the preparation method of the self-temperature-limiting heat tracing belt cable comprises the following steps: step one, preparing a PTC composite material; step two, fully mixing; step three, cooling and extruding; step four, coating an insulating layer; step five, irradiation crosslinking; step six, weaving a shielding layer; step seven, extruding and wrapping a protective sleeve; and step eight, detecting and packaging. When the self-temperature-limiting heat tracing cable is prepared, the formula of the used PCT composite material is reasonable, and due to the addition of the two-component thermoplastic polymer, a stable system is formed among the PCT composite materials, so that the advantages of the performance are complementary, the resistance reproducibility and stability are good, the price can be greatly reduced, the production cost is reduced, the prepared self-temperature-limiting heat tracing cable still has the stable characteristic of high electrical performance after being placed at high temperature for a long time, and the service life of the self-temperature-limiting heat tracing cable is prolonged.)

1. The preparation method of the self-temperature-limiting heat tracing belt cable is characterized by comprising the following steps of: the method comprises the following steps:

step one, preparing a PTC composite material: the PTC composite material is composed of 60-70 parts by weight of thermoplastic polymer, 10-20 parts by weight of fluororubber, 10-20 parts by weight of carbon black, 1-2 parts by weight of zinc oxide and 5-10 parts by weight of auxiliary agent, and all the components are weighed and added into a mixing roll for mixing to obtain a PTC composite material mixture A;

step two, fully mixing: keeping the mixture fluidity of the PTC composite material mixture A obtained in the step one through the friction extrusion effect of double-screw melt extrusion equipment, and fully mixing the mixture A for 20-30 minutes at the temperature of 100-120 ℃ to obtain a PTC composite material mixture B;

step three, cooling and extruding: the double-screw melt extrusion equipment weakens the friction extrusion effect of the double screws by changing the structure of the screw grooves, the PTC composite material mixture B prepared in the step two is gradually cooled to be below the melting temperature through natural cooling of outside air, and then the PTC composite material mixture B is extruded to be wrapped outside two copper core buses which are arranged in parallel, so that the self-temperature-limiting heat tracing cable core belt is obtained;

step four, coating with an insulating layer: coating an insulating layer on the outer layer of the self-temperature-limiting heat tracing cable core belt obtained in the step three;

step five, irradiation crosslinking: performing irradiation crosslinking on the self-temperature-limiting heat tracing cable core belt coated with the insulating layer in the fourth step by using an electron accelerator, and obtaining a usable heat tracing belt with the insulating layer after irradiation treatment;

step six, weaving a shielding layer: a shielding layer is wrapped outside the insulating layer of the heat tracing band of the five insulating layers through metal fiber mixed weaving;

step seven, extruding and wrapping the protective sleeve: extruding a sheath layer outside the shielding layer in the sixth step by using an ethylene propylene rubber material;

step eight, detection and packaging: and after the power-on and power-off stability is detected to be qualified, the cable can be obtained from the temperature-limited heat tracing band cable after being packaged.

2. The method of preparing a self-limiting temperature heat tracing ribbon cable of claim 1, wherein: the detailed steps of the preparation of the PTC composite material are as follows:

a. controlling the temperature of the surface of a front roller of the mixing roll to 185 +/-5 ℃ and the temperature of the surface of a rear roller to 180 +/-5 ℃ for 30 minutes, then sequentially adding the thermoplastic polymer, the fluororubber and the carbon black, and mixing for 10-16 minutes;

b. putting zinc oxide and an auxiliary agent into a stirring machine, and stirring and mixing for 6-10 minutes;

c. and putting the mixture into a mixing roll again, and mixing for 9-16 minutes to obtain the PTC composite material mixture A.

3. The method of preparing a self-limiting temperature heat tracing ribbon cable of claim 1, wherein: the thermoplastic polymer consists of a component A and a component B, wherein the component A is polypropylene, and the component B is high-density polyethylene, low-density polyethylene, linear low-density polyethylene or polyvinylidene fluoride; the mass ratio of the component A to the component B is 1: 3.

4. the method of preparing a self-limiting temperature heat tracing ribbon cable of claim 2, wherein: the particle size of the carbon black is less than or equal to 200 nanometers, and the particle size of the zinc oxide is less than or equal to 100 nanometers.

5. The method of preparing a self-limiting temperature heat tracing ribbon cable of claim 1, wherein: the insulating layer is low-smoke halogen-free flame-retardant thermoplastic polyolefin, the low-smoke halogen-free flame-retardant thermoplastic polyolefin is formed by mixing and extruding a first component and a second component according to the mass ratio of 3: 7, the first component is a thermoplastic elastomer for realizing in-situ polymerization of ethylene and octene of a metallocene catalyst, and the second component is an ethylene-vinyl acetate copolymer.

6. The method of preparing a self-limiting temperature heat tracing ribbon cable of claim 1, wherein: and fifthly, respectively taking the irradiation dose of irradiation crosslinking as 0.150 kGy and 380kGy, the energy as 1.2-1.6 MeV, the beam current as 20-30 mA, and the irradiation atmosphere as air.

7. The method of preparing a self-limiting temperature heat tracing ribbon cable of claim 1, wherein: the metal shielding layer is formed by adding a tinned copper wire and an aramid fiber wire to weave shielding after aluminum tape longitudinal wrapping shielding.

8. The method of preparing a self-limiting temperature heat tracing ribbon cable of claim 1, wherein: the auxiliary agent is more than two of an antioxidant, a crosslinking sensitizer, a flame retardant, a stabilizer and a dispersing agent.

9. The method of preparing a self-limiting temperature heat tracing ribbon cable of claim 1, wherein: the two copper-core buses are both tin-plated copper stranded wires or nickel-plated copper stranded wires, and the distance between the two copper-core buses is 6-12 mm.

Technical Field

The invention relates to the technical field of cable preparation, in particular to a preparation method of a self-temperature-limiting heat tracing belt cable.

Background

The self-temperature-limiting heat tracing cable is a flat ribbon cable consisting of a conductive polymer composite material (plastic), two parallel metal wires and an insulating sheath. The conductive polymer composite material has the characteristic of Positive Temperature Coefficient (PTC), is connected in parallel, can automatically adjust output power along with the temperature change of a heated system, and automatically limits the heating temperature, and the PTC characteristic is the positive temperature coefficient effect and is the characteristic that the resistivity of the material increases along with the temperature rise and sharply increases in a certain temperature interval.

The resistivity of the heating element of the self-temperature-limiting heat tracing cable has a very high Positive Temperature Coefficient (PTC) and is connected in parallel, the existing self-temperature-limiting heat tracing cable has poor stability, and when the heat tracing cable generates heat and is self-limited, because of the great difference of the thermal expansion rates of the conductive electrode made of metal and the high molecular base material, when the temperature returns to the normal temperature, the interface resistance between the conductive electrode made of metal and the high molecular base material is increased, finally, the normal use of the self-temperature-limiting heat tracing cable is adversely affected, and the service life of the self-temperature-limiting heat tracing cable is shortened.

Disclosure of Invention

Technical problem to be solved

1. Technical problem to be solved

The invention aims to provide a preparation method of a self-temperature-limiting heat tracing belt cable, which has the advantages of good stability and long service life and solves the problems that the existing self-temperature-limiting heat tracing cable has poor stability, and when the heat tracing cable generates heat and is subjected to self-limiting temperature, because the thermal expansion rates of a conductive electrode made of a metal material and a high polymer base material are greatly different, the interface resistance between the conductive electrode made of the metal material and the high polymer base material is increased when the temperature returns to normal temperature, the normal use of the self-temperature-limiting heat tracing belt cable is finally adversely affected, and the service life of the self-temperature-limiting heat tracing cable is shortened.

(II) technical scheme

In order to achieve the purpose, the invention provides the following technical scheme: the preparation method of the self-temperature-limiting heat tracing belt cable comprises the following steps:

step one, preparing a PTC composite material: the PTC composite material is composed of 60-70 parts by weight of thermoplastic polymer, 10-20 parts by weight of fluororubber, 10-20 parts by weight of carbon black, 1-2 parts by weight of zinc oxide and 5-10 parts by weight of auxiliary agent, and all the components are weighed and added into a mixing roll for mixing to obtain a PTC composite material mixture A;

step two, fully mixing: keeping the mixture fluidity of the PTC composite material mixture A obtained in the step one through the friction extrusion effect of double-screw melt extrusion equipment, and fully mixing the mixture A for 20-30 minutes at the temperature of 100-120 ℃ to obtain a PTC composite material mixture B;

step three, cooling and extruding: the double-screw melt extrusion equipment weakens the friction extrusion effect of the double screws by changing the structure of the screw grooves, the PTC composite material mixture B prepared in the step two is gradually cooled to be below the melting temperature through natural cooling of outside air, and then the PTC composite material mixture B is extruded to be wrapped outside two copper core buses which are arranged in parallel, so that the self-temperature-limiting heat tracing cable core belt is obtained;

step four, coating with an insulating layer: coating an insulating layer on the outer layer of the self-temperature-limiting heat tracing cable core belt obtained in the step three;

step five, irradiation crosslinking: performing irradiation crosslinking on the self-temperature-limiting heat tracing cable core belt coated with the insulating layer in the fourth step by using an electron accelerator, and obtaining a usable heat tracing belt with the insulating layer after irradiation treatment;

step six, weaving a shielding layer: a shielding layer is wrapped outside the insulating layer of the heat tracing band of the five insulating layers through metal fiber mixed weaving;

step seven, extruding and wrapping the protective sleeve: extruding a sheath layer outside the shielding layer in the sixth step by using an ethylene propylene rubber material;

step eight, detection and packaging: after the power-on and power-off stability is detected to be qualified, the cable can be packaged to obtain the temperature-limited heat tracing band cable

Preferably, the detailed steps of the preparation of the PTC composite are as follows:

a. controlling the temperature of the surface of a front roller of the mixing roll to 185 +/-5 ℃ and the temperature of the surface of a rear roller to 180 +/-5 ℃ for 30 minutes, then sequentially adding the thermoplastic polymer, the fluororubber and the carbon black, and mixing for 10-16 minutes;

b. putting zinc oxide and an auxiliary agent into a stirring machine, and stirring and mixing for 6-10 minutes;

c. and putting the mixture into a mixing roll again, and mixing for 9-16 minutes to obtain the PTC composite material mixture A.

Preferably, the thermoplastic polymer consists of a component A and a component B, wherein the component A is polypropylene, and the component B is high-density polyethylene, low-density polyethylene, linear low-density polyethylene or polyvinylidene fluoride; the mass ratio of the component A to the component B is 1: 3.

preferably, the particle diameter of the carbon black is not more than 200 nm, and the particle diameter of the zinc oxide is not more than 100 nm.

Preferably, the insulating layer is low-smoke halogen-free flame-retardant thermoplastic polyolefin, the low-smoke halogen-free flame-retardant thermoplastic polyolefin is formed by mixing and extruding a first component and a second component according to the mass ratio of 3: 7, the first component is a thermoplastic elastomer for realizing in-situ polymerization of ethylene and octene of a metallocene catalyst, and the second component is an ethylene-vinyl acetate copolymer.

Preferably, the irradiation dose of irradiation crosslinking in the fifth step is 0.150 kGy and 380kGy respectively, the energy is 1.2-1.6 MeV, the beam current is 20-30 mA, and the irradiation atmosphere is air.

Preferably, the metal shielding layer is formed by longitudinally wrapping and shielding an aluminum tape and then adding a tinned copper wire and an aramid fiber wire to weave and shield.

Preferably, the auxiliary agent is more than two of an antioxidant, a crosslinking sensitizer, a flame retardant, a stabilizer and a dispersing agent.

Preferably, the two copper-core buses are both tin-plated copper stranded wires or nickel-plated copper stranded wires, and the distance between the two copper-core buses is 6-12 mm.

(III) advantageous effects

Compared with the prior art, the invention provides a preparation method of a self-temperature-limiting heat tracing belt cable, which has the following beneficial effects:

(1) when the self-temperature-limiting heat tracing belt cable is prepared, the used PCT composite material has a reasonable formula, and due to the addition of the two-component thermoplastic polymer, a stable system is formed among the PCT composite materials, so that the PCT composite material has complementary advantages in performance, good resistance reproducibility and stability, greatly reduced price and reduced production cost.

(2) The self-temperature-limiting heat tracing cable prepared by the invention still has high stability of electrical performance after being placed at high temperature for a long time, and the service life of the self-temperature-limiting heat tracing cable is prolonged.

(3) Adopt aluminium strip to indulge the shielding layer of covering after the shielding with tin-plated copper wire and aramid fiber silk and weaving can play effects such as prevent static, anticreep short circuit, stretch-proofing, improve the practicality of self-limiting temperature companion's hot-line cable.

(4) The integral flame-retardant function of the self-temperature-limiting heat tracing band cable is realized by adopting an insulating layer made of low-smoke halogen-free flame-retardant thermoplastic polyolefin material with specific components.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.