Polypropylene cable production process

Abstract

The invention discloses a polypropylene cable production process. The polypropylene cable production process comprises a raw material pretreatment step, a rotary extrusion molding step and an oil cooling shaping step, the raw material pretreatment step comprises the steps of drying, screening and modification treatment of a polypropylene raw material, and the modification treatment comprises the steps of adding an antioxidant and a nucleating agent into the polypropylene raw material and uniformly mixing; in the rotary extrusion molding step, an extruder with a rotary die head is adopted, the rotation speed of the rotary die head is matched with the melt flow rate of the polypropylene raw material, and the temperature of a machine barrel of the extruder is set in sections; the oil cooling shaping step is arranged at the discharging end of the rotary extrusion forming step, mineral oil is adopted as an oil cooling medium, and the polypropylene cable is directly immersed in the oil cooling medium to be cooled after being extruded. The polypropylene cable production process disclosed by the invention has the beneficial effects that the characteristics of a polypropylene material are adapted to solve the problems of high flowability, easiness in eccentricity and the like.

Description

Technical Field

[0001] This invention belongs to the field of polypropylene cable production, and specifically relates to a polypropylene cable production process. Background Technology

[0002] The patent, with publication number CN103804798A and subject name, is an invention patent for a halogen-free flame-retardant polyethylene sheath material for ultra-high voltage cables and its preparation method and application. Its IPC classification number is C08L23 / 16. Its technical solution discloses "(1) mixing all raw materials evenly; (2) putting the material obtained in step 1 into a twin-screw extruder for extrusion granulation. The temperature of the twin-screw extruder is set as follows: barrel zone 1 150-155℃, barrel zone 2 160-165℃, barrel zone 3 170-175℃, barrel zone 4 180-185℃, barrel zone 5 190-195℃, and die head and mold 170-180℃".

[0003] Therefore, the above-mentioned invention patents have disclosed one technical solution for the preparation of halogen-free flame-retardant polyethylene sheath material for ultra-high voltage cables. However, the technical solutions disclosed in the above-mentioned invention patents focus on the absence of halogen elements and do not further solve the problems of high fluidity and easy eccentricity, which require further improvement. Summary of the Invention

[0004] In view of the current situation of the prior art, this invention overcomes the above-mentioned defects and provides a polypropylene cable production process.

[0005] This invention adopts the following technical solution: a polypropylene cable production process, including a raw material pretreatment step, a rotary extrusion molding step, and an oil cooling and shaping step, wherein: The raw material pretreatment steps include drying, sieving and modification of polypropylene raw materials. The modification process involves adding antioxidants and nucleating agents to the polypropylene raw materials and mixing them evenly. The rotary extrusion molding step uses an extruder with a rotary die head. The rotation speed of the rotary die head is matched with the melt flow rate of the polypropylene raw material, and the barrel temperature of the extruder is set in stages. The oil-cooling and shaping step is set at the discharge end of the rotary extrusion molding step, and mineral oil is used as the oil-cooling medium. After the polypropylene cable is extruded, it is directly immersed in the oil-cooling medium for cooling.

[0006] As a preferred technical solution of the above technical solution, the raw material pretreatment step includes drying, sieving and modification of polypropylene raw material. The modification treatment involves adding 0.5-2wt% antioxidant and 1-3wt% nucleating agent to the polypropylene raw material and mixing them evenly to obtain the pretreated raw material.

[0007] As a preferred technical solution of the above technical solution, the drying temperature is 80-100℃, the drying time is 2-4h, and the relative humidity of the drying environment is ≤30%; the screening process uses a 100-120 mesh screen, and the raw material conveying speed is controlled at 0.5-1m / s during the screening process.

[0008] As a preferred embodiment of the above technical solution, the rotary extrusion molding step uses an extruder with a rotary die head. The rotational speed of the rotary die head is matched with the melt flow rate of the polypropylene raw material. The rotational speed range of the rotary die head is 10-60 r / min, and the barrel temperature of the extruder is set in segments of 160-180℃, 180-200℃, 200-220℃, and 210-230℃.

[0009] As a preferred embodiment of the above technical solutions, the rotating die head includes an inner die and an outer die, with an annular extrusion channel formed between the inner die and the outer die. The inner die can rotate relative to the outer die, and the rotation of the inner die is driven by a servo motor with a rotational speed accuracy of ±1 r / min. The gap of the annular extrusion channel is 0.8-2.5 mm, and the gap size is adaptively adjusted according to the preset thickness of the polypropylene cable.

[0010] As a preferred embodiment of the above technical solutions, the screw speed of the extruder is 20-50 r / min, the screw compression ratio is 2.5-3.5:1, and the feed inlet temperature is 100-120℃.

[0011] As a preferred technical solution to the above technical solutions, the polypropylene cable production process further includes subsequent processing steps, which include traction, cutting, inspection and packaging. The traction speed is matched with the extrusion speed of the rotary extrusion molding step, with a traction speed of 0.5-2m / min and a traction tension of 50-200N.

[0012] The polypropylene cable production process disclosed in this invention has the advantage of adapting to the characteristics of polypropylene materials to solve problems such as high fluidity and easy eccentricity. Moreover, the above steps are only applicable to the production of polypropylene cables and cannot be applied to the production of polyethylene cables. Detailed Implementation

[0013] This invention discloses a polypropylene cable manufacturing process. The specific implementation of this invention will be further described below with reference to a preferred embodiment (Example 1).

[0014] Example 1.

[0015] Preferably, the polypropylene cable manufacturing process includes a raw material pretreatment step, a rotary extrusion molding step, and an oil cooling and shaping step, wherein: The raw material pretreatment steps include drying, sieving and modification of polypropylene raw materials. The modification process involves adding antioxidants and nucleating agents to the polypropylene raw materials and mixing them evenly. The rotary extrusion molding step uses an extruder with a rotary die head. The rotation speed of the rotary die head is matched with the melt flow rate of the polypropylene raw material, and the barrel temperature of the extruder is set in stages. The oil cooling and shaping step is set at the discharge end of the rotary extrusion molding step, and mineral oil is used as the oil cooling medium. After the polypropylene cable is extruded, it is directly immersed in the oil cooling medium for cooling. This is equivalent to the rotary extrusion molding step and the oil cooling and shaping step working together to adapt to the characteristics of polypropylene materials and solve problems such as high fluidity and easy eccentricity. Moreover, the above steps are only applicable to the production of polypropylene cables and cannot be applied to the production of polyethylene cables.

[0016] The raw material pretreatment step includes drying, sieving, and modification of polypropylene raw materials. The modification involves adding 0.5-2 wt% antioxidant and 1-3 wt% nucleating agent to the polypropylene raw materials, mixing them evenly to obtain pretreated raw materials. Drying removes moisture from the polypropylene raw materials to prevent air bubbles from forming during extrusion and affecting cable quality. Sieving removes impurities and improves the purity of the raw materials. Adding antioxidants and nucleating agents optimizes the processing and mechanical properties of the polypropylene material, laying a good foundation for subsequent rotary extrusion molding steps.

[0017] The drying process involves a temperature of 80-100℃, a drying time of 2-4 hours, and a relative humidity of ≤30%. The screening process uses a 100-120 mesh screen, with the raw material conveying speed controlled at 0.5-1 m / s. By controlling the drying temperature, time, and humidity, the polypropylene raw material is ensured to be fully dehydrated without thermal degradation. Appropriate selection of screen mesh size and conveying speed effectively removes impurities while avoiding raw material accumulation or inefficiency caused by over-screening.

[0018] The rotary extrusion molding step employs an extruder with a rotary die. The rotational speed of the rotary die is matched to the melt flow rate of the polypropylene raw material. The rotational speed range of the rotary die is 10-60 r / min, and the barrel temperature of the extruder is set in segments of 160-180℃, 180-200℃, 200-220℃, and 210-230℃. By using a rotary die to achieve rotary extrusion, and by matching the rotational speed with the melt flow rate of polypropylene, the uneven melt flow caused by the high fluidity of polypropylene can be effectively offset, reducing eccentricity. The segmented barrel temperature settings are consistent with the melting characteristics of polypropylene material, ensuring that the raw material is fully melted and its performance is stable, thereby improving the extrusion molding quality.

[0019] The rotating die head includes an inner die and an outer die, forming an annular extrusion channel between them. The inner die can rotate relative to the outer die, and its rotation is driven by a servo motor with a speed accuracy of ±1 r / min. The gap of the annular extrusion channel is 0.8-2.5 mm, and the gap size is adaptively adjusted according to the preset thickness of the polypropylene cable. High-precision speed control ensures the stability of rotary extrusion and avoids uneven cable wall thickness caused by speed fluctuations. The adjustable annular extrusion channel gap can adapt to the production needs of polypropylene cables of different specifications, improve the versatility of the process, and accurately control the cable wall thickness to further improve the eccentricity problem.

[0020] The extruder features a screw speed of 20-50 r / min, a screw compression ratio of 2.5-3.5:1, and a feed inlet temperature of 100-120℃ to prevent premature melting and agglomeration of the polypropylene raw material at the feed inlet. Reasonable screw speed and compression ratio settings ensure that the polypropylene melt is fully plasticized and uniformly mixed within the barrel, improving melt quality. Controlling the feed inlet temperature prevents premature melting and agglomeration of the raw material, ensuring smooth feeding, improving production efficiency, and preventing agglomerated raw material from affecting the cable molding quality.

[0021] The polypropylene cable production process also includes subsequent processing steps, including traction, cutting, inspection, and packaging. The traction speed is matched with the extrusion speed of the rotary extrusion molding step, with a traction speed of 0.5-2 m / min and a traction tension of 50-200 N. Matching the traction speed with the extrusion speed avoids cable stretching deformation or accumulation caused by speed mismatch, ensuring continuous cable production. Precise control of the traction tension ensures smooth cable traction while avoiding cable breakage due to excessive tension or cable slack due to insufficient tension, thus improving production stability and product qualification rate.

[0022] The rotational speed range of the rotating die head is based on the melt flow rate of polypropylene. When the melt flow rate of polypropylene is 1-10 g / 10 min, a rotational speed of 10-60 r / min can effectively control the uniformity of melt flow. However, the melt flow rate of polyethylene is even lower. This rotational speed range will cause the polyethylene melt flow rate to be too fast, making it impossible to form a uniform annular melt film, which in turn leads to severe cable eccentricity and uneven wall thickness.

[0023] The rotary die head is equipped with a sealing structure, which employs a double-layer seal. The inner layer is a high-temperature resistant elastic seal adapted to the working temperature of the rotary die head, while the outer layer is a mechanical seal to enhance sealing performance. Simultaneously, a lubrication and cooling channel is provided at the sealing structure, through which a cooling and lubricating medium is introduced to maintain the temperature of the sealing area ≤80℃. This improves the sealing performance of the rotary die head, prevents polypropylene melt leakage, and ensures production safety and environmental hygiene. The lubrication and cooling channel effectively reduces the temperature of the sealing area, extends the service life of the seal, reduces equipment maintenance costs, and improves the continuity and stability of the process.

[0024] It is worth mentioning that the specific components and other technical features of the cooling and lubricating medium involved in this patent application should be regarded as prior art. The specific structure, working principle, and possible control methods and spatial arrangement of these technical features can be conventionally selected in the field and should not be regarded as the inventive point of this patent. This patent will not be further elaborated in detail.

[0025] For those skilled in the art, modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

Claims

1. A polypropylene cable manufacturing process, characterized in that, This includes raw material pretreatment, rotary extrusion molding, and oil cooling and setting steps, among which: The raw material pretreatment steps include drying, sieving and modification of polypropylene raw materials. The modification process involves adding antioxidants and nucleating agents to the polypropylene raw materials and mixing them evenly. The rotary extrusion molding step uses an extruder with a rotary die head. The rotation speed of the rotary die head is matched with the melt flow rate of the polypropylene raw material, and the barrel temperature of the extruder is set in stages. The oil-cooling and shaping step is set at the discharge end of the rotary extrusion molding step, and mineral oil is used as the oil-cooling medium. After the polypropylene cable is extruded, it is directly immersed in the oil-cooling medium for cooling.

2. The polypropylene cable manufacturing process according to claim 1, characterized in that, The raw material pretreatment step includes drying, sieving, and modification of polypropylene raw materials. The modification process involves adding 0.5-2 wt% antioxidant and 1-3 wt% nucleating agent to the polypropylene raw materials and mixing them evenly to obtain the pretreated raw materials.

3. The polypropylene cable manufacturing process according to claim 1, characterized in that, The drying process is carried out at a temperature of 80-100℃ for 2-4 hours, with a relative humidity of ≤30%. The screening process uses a 100-120 mesh screen, and the raw material conveying speed is controlled at 0.5-1m / s during the screening process.

4. The polypropylene cable manufacturing process according to claim 1, characterized in that, The rotary extrusion molding step uses an extruder with a rotary die. The rotational speed of the rotary die is matched with the melt flow rate of the polypropylene raw material. The rotational speed range of the rotary die is 10-60 r / min. The barrel temperature of the extruder is set in segments of 160-180℃, 180-200℃, 200-220℃, and 210-230℃.

5. The polypropylene cable manufacturing process according to claim 1, characterized in that, The rotating die head includes an inner die and an outer die, with an annular extrusion channel formed between the inner die and the outer die. The inner die can rotate relative to the outer die. The rotation of the inner die is driven by a servo motor with a rotational speed accuracy of ±1 r / min. The gap of the annular extrusion channel is 0.8-2.5 mm, and the gap size is adaptively adjusted according to the preset thickness of the polypropylene cable.

6. The polypropylene cable manufacturing process according to claim 1, characterized in that, The screw speed of the extruder is 20-50 r / min, the screw compression ratio is 2.5-3.5:1, and the feed inlet temperature is 100-120℃.

7. The polypropylene cable manufacturing process according to claim 1, characterized in that, The polypropylene cable production process also includes subsequent processing steps, including traction, cutting, inspection and packaging. The traction speed is matched with the extrusion speed of the rotary extrusion molding step, with a traction speed of 0.5-2m / min and a traction tension of 50-200N.