Preparation method and application of PVC-based granular material for cable sheath

Abstract

The invention provides a preparation method and application of a PVC-based granular material for a cable sheath. The preparation method comprises the following steps: premixing 30 to 50 weight percent of regenerated PVC crushed material and 50 to 70 weight percent of raw PVC powder at the temperature of between 60 and 80 DEG C to form PVC resin; the preparation method comprises the following steps: blending a mixed material containing 100 parts by mass of PVC resin, 20-40 parts by mass of a plasticizer, 10-15 parts by mass of a stabilizer, 20-25 parts by mass of a filler, 1.0-1.8 parts by mass of a lubricant and 50-60 parts by mass of optional other auxiliaries, and then extruding and granulating to prepare the PVC-based granular material for the cable sheath. The PVC-based granular material for the cable sheath prepared by the preparation method provided by the invention has good flowability and formability in the processing process, also has good mechanical properties and chemical stability, and also can reduce the cost of raw materials for preparing the cable sheath.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cable sheath preparation, and particularly relates to a preparation method of PVC-based granular material for cable sheath and application thereof. BACKGROUND

[0002] As the outer protective structure of the cable, the cable sheath has important functions such as mechanical protection, corrosion resistance, flame resistance, and temperature resistance. Its technical evolution is closely related to the overall development of the cable industry. In recent years, the market size of domestic PVC cable sheath material has continued to expand, reaching 15 million tons in 2023, and the compound growth rate is expected to reach 8% in the next five years. This growth is mainly due to the expansion of power infrastructure, the increasing demand for new energy (such as wind power and photovoltaic) supporting needs, and the urgent need for high-reliability cables in the construction of smart grids. These factors have collectively driven the cable sheath industry to continue to develop. However, the granular material used to prepare the cable sheath in the prior art has the problems of insufficient mechanical properties, poor processing fluidity, and poor thermal stability.

[0003] PVC mulch is widely used in farmland in China, but the recycling rate of waste PVC mulch is low. A large amount of discarded PVC mulch cannot be effectively collected and is randomly discarded in the field or simple landfill, not only long-term polluting the soil and water environment, but also causing a huge loss of material resources. Even the recycled part is mostly downcycled and reused, such as making low-end building materials, which does not fully utilize the inherent performance value of PVC, and the overall recycling rate is much lower than the potential demand. Therefore, it is of great significance to develop a method for preparing PVC-based granular material for cable sheath based on waste PVC mulch to simultaneously solve the problems of high production cost, poor performance of cable sheath granular material, and low recycling rate of waste PVC mulch. SUMMARY

[0004] To solve all or part of the above technical problems, the application provides the following technical solutions:

[0005] The first aspect of the application provides a preparation method of PVC-based granular material for cable sheath, which comprises:

[0006] Pre-mixing 30-50 wt% of recycled PVC broken material and 50-70 wt% of virgin PVC powder at 60-80℃ to form a PVC resin;

[0007] Blending a mixture containing 100 parts by mass of the PVC resin, 20-40 parts by mass of a plasticizer, 10-15 parts by mass of a stabilizer, 20-25 parts by mass of a filler, and 1.0-1.8 parts by mass of a lubricant, and then extruding and granulating to obtain the PVC-based granular material for cable sheath.

[0008] The cable sheath PVC-based granular material prepared by the method has good fluidity and forming property in the processing process, and also has good mechanical property and chemical stability, and can also reduce the raw material cost of preparing the cable sheath. The PVC is melted by heat and changes from solid to fluid to realize the uniform mixing of the virgin PVC powder and the recycled PVC crushed material under the temperature condition of 60-80℃. If the virgin PVC powder and the recycled PVC crushed material are not uniformly mixed, the performance of the granular material will be poor, which is not conducive to the downstream application.

[0009] In some embodiments, the average polymerization degree of the virgin PVC powder is 1250-1350.

[0010] In some embodiments, the particle size of the PVC resin is 3-5mm.

[0011] In some embodiments, the plasticizer includes at least one of a general-purpose plasticizer, a heat-stable and / or flame-retardant plasticizer. By adding the plasticizer, the melting temperature of the PVC resin can be reduced, and the fluidity and softness of the PVC resin in the molten state can be improved. The "heat-stable and / or flame-retardant plasticizer" includes two types of heat-stable plasticizer and flame-retardant plasticizer, and also represents a plasticizer with both heat stability and flame retardancy.

[0012] In some embodiments, the general-purpose plasticizer includes one or a combination of dioctyl phthalate, dinonyl phthalate, dioctyl terephthalate, and trioctyl trimellitate.

[0013] In some embodiments, the heat-stable and / or flame-retardant plasticizer includes one or a combination of an epoxy compound, a phosphate compound, and a halogenated hydrocarbon compound. The epoxy compound belongs to a heat-stable plasticizer, the halogenated hydrocarbon compound belongs to a flame-retardant plasticizer, and the phosphate compound belongs to both a heat-stable plasticizer and a flame-retardant plasticizer.

[0014] In some preferred embodiments, the plasticizer includes a general-purpose plasticizer and a heat-stable and / or flame-retardant plasticizer, and the mass ratio of the general-purpose plasticizer to the heat-stable and / or flame-retardant plasticizer is 1:0.1-0.2.

[0015] In some embodiments, the stabilizer includes at least one of organic tin, calcium-zinc stabilizer, and calcium stearate.

[0016] In some preferred embodiments, the stabilizer comprises organic tin and calcium stearate in a mass ratio of 1:0.1-0.2, or the stabilizer comprises calcium-zinc stabilizer and calcium stearate in a mass ratio of 1:0.1-0.2. The two kinds of combined stabilizers can effectively prevent thermal decomposition and light aging of the PVC resin during processing and use.

[0017] In some embodiments, the filler comprises calcium carbonate, but is not limited thereto. The inorganic filler mainly comprising calcium carbonate or other calcium powder can fill the pores in the PVC matrix through the filler, thereby increasing the material density and hardness, enhancing the rigidity, strength and wear resistance, improving the thermal stability and anti-aging performance, reducing the burning speed and smoke density, and improving the flame retardation performance and safety. In some embodiments, the calcium carbonate has a mesh number of 800-3000 mesh.

[0018] In some embodiments, the lubricant comprises polyethylene wax and / or chlorinated paraffin, oxidized polyethylene and lipid substance in a mass ratio of 1:0.1-0.3:1-3. The combined lubricant can improve the processing fluidity of the PVC resin, and reduce the energy consumption and wear during processing. The lipid substance comprises one or more of epoxy soybean oil, glycerol or monoglyceride.

[0019] In some embodiments, the mixture further comprises 50-60 parts by mass of an auxiliary agent. The auxiliary agent can be used to adjust the forming appearance and special performance of the granular material to meet different application requirements, and thus appropriate auxiliary agent such as flame retardant and / or colorant can be added as needed.

[0020] In some embodiments, the auxiliary agent comprises flame retardant and colorant in a mass ratio of 1:0.03-0.04.

[0021] In some embodiments, the source of the recycled PVC broken material comprises: sequentially performing cleaning, crushing and rubbing and dehydration treatment on the collected waste PVC mulch to obtain the recycled PVC broken material.

[0022] Further, the cleaning is mechanical cleaning, which comprises cutting and dividing the collected waste PVC mulch, and then dry cleaning the waste PVC mulch.

[0023] Further, the crushing and rubbing comprises: crushing the waste PVC mulch after the cleaning, and then performing high-speed rubbing treatment on the crushed waste PVC mulch at 1500-2200 rpm.

[0024] In some embodiments, the dehydration treatment comprises rinsing the waste PVC mulch after the crushing and rubbing, and then dehydrating the waste PVC mulch, wherein the mixture is prepared after the dehydration rate reaches 98% or more.

[0025] In some embodiments, the blending comprises: firstly, hot mixing at a temperature of 150-180℃ for 10-15 minutes, and then cold mixing at a temperature of 40-50℃ for 5-10 minutes. The purpose of the first hot mixing is to make the PVC and other additives into a fluid, and to realize the uniform distribution of the additives in the PVC in a flowing state. At a temperature of 150-180℃, part of the additives can be coupled with the molecular chains of the PVC, thereby improving the structure and performance of the granules. After the additives enter the PVC fluid in the hot mixing, the additives and the PVC form a whole and firm structure by means of cooling (cold mixing).

[0026] For example, the blending specifically comprises: placing the mixed materials in a feeding station, pre-mixing and buffering in a pre-mixing bin, blowing to a metering tank by air, and then entering a hot mixing unit under the action of gravity after metering. The rotation speed of the main shaft of the hot mixing unit is controlled to be 600-650 rpm, and the temperature is controlled to be 150-180℃. After the hot mixing, the materials flow to a cold mixing unit by themselves. The rotation speed of the main shaft of the cold mixing unit is 65 rpm, and the temperature is 40-50℃. The materials are stirred for 10-15 minutes under the hot mixing condition, and are stirred for 5-10 minutes under the cold mixing condition.

[0027] In some embodiments, the temperature for the extrusion granulation is 170-180℃. For example, the extrusion granulation specifically comprises: after the blended PVC fluid is sent to a PVC mixing buffer bin, the PVC fluid is heated by a granulation main machine. The temperature of the granulation main machine is controlled to be 170-180℃, the extrusion output is controlled to be 400-500 kg / h, and the granulation is performed by the granulation main machine. The cutting diameter is controlled to be 3.5 mm. After the granulation, the unqualified products are removed by a cyclone separator and a vibrating screen, and the qualified products enter a PVC mixing material finished product bin.

[0028] The second aspect of the present application provides a PVC-based granule for cable sheath, which is prepared by the preparation method described in any one of the technical solutions.

[0029] The third aspect of the present application provides the application of the PVC-based granule for cable sheath in the preparation of a cable sheath.

[0030] The method for preparing the cable sheath by using the PVC-based granule for cable sheath can comprise: melting, injection molding and forming treatment of the PVC-based granule for cable sheath, so as to obtain the cable sheath.

[0031] Compared with the prior art, the application has at least the following beneficial effects: the waste PVC mulch is recycled, and is treated by mechanical cleaning, crushing and rubbing, cleaning and dewatering, etc., to obtain regenerated PVC crushed material with high purity, and the regenerated PVC crushed material is compounded with virgin PVC powder, and plasticizers, stabilizers, fillers, lubricants, etc., are added, to prepare a PVC-based granular material for cable sheath; the PVC-based granular material for cable sheath prepared based on the compounding of the regenerated PVC material and the virgin PVC powder has good mechanical properties, chemical stability, fluidity and formability. DETAILED DESCRIPTION

[0032] The technical solutions of the application are described in detail below with reference to specific embodiments, so that those skilled in the art can better understand and implement the technical solutions of the application. The specific functional details disclosed herein should not be interpreted as limiting, but only as a basis for the claims and for teaching those skilled in the art to employ the representative basis of the application in different ways in any appropriate detailed embodiment in fact.

[0033] In addition, unless otherwise specified, the various raw materials used in the following examples can be obtained from the market or the like, and the various production and testing equipment used is known in the art, and the testing methods used are also known in the art.

[0034] Example 1

[0035] Example 1 provides a PVC-based granular material for cable sheath and a preparation method thereof, specifically comprising the following steps:

[0036] 1. Collecting waste PVC mulch, and sequentially performing mechanical cleaning, crushing and rubbing, and cleaning and dewatering treatment thereon:

[0037] (1) Mechanical cleaning: the PVC waste mulch containing impurities recovered mechanically is poured into a feed bin, and is sent to a cutting machine for segmentation through a screw feeder, and the segmented PVC mulch is then conveyed to a film dry cleaning machine through a belt conveyor, the PVC waste mulch is separated from large-particle impurities such as branches and soil in the film dry cleaning machine, and then the mechanically cleaned PVC mulch is continuously conveyed to the outside of the equipment through a parallel impurity conveyor inside the film dry cleaning machine.

[0038] (2) Crushing and rubbing: the mechanically cleaned PVC mulch conveyed by the parallel impurity conveyor is sent to a crusher through a belt conveyor for crushing, to obtain regenerated PVC material, and the crushed regenerated PVC material is then sent to a high-speed rubbing machine by a screw feeder, under the action of the blades, the process of manual rubbing is simulated, and preliminary separation of the regenerated PVC material from small particles of soil is realized.

[0039] (3) washing and dewatering: the regenerated PVC material after rubbing by the high-speed rubbing machine is directly put into the rinsing pool, soaked in the rinsing pool, and sent to the spiral feeder under the driving of the rolling brush. The regenerated PVC material is sent to the dewatering machine by the spiral feeder for dewatering, and the dewatered regenerated PVC material is sent to the cyclone bin through the cyclone separator.

[0040] 2, the mixture is prepared by using the regenerated PVC material obtained above, and the composition of the mixture is shown in Table 1 according to mass fraction:

[0041] Table 1

[0042]

[0043]

[0044] All the above raw materials are added to the mixing machine through the feeding station according to the specified weight fraction, uniformly mixed in the mixing machine, and fully dispersed to form the mixture.

[0045] 2, the mixture is placed in the feeding station, pre-mixed and buffered in the pre-mixing bin, and then air-blowing to the metering tank for metering. The metered material enters the hot mixing machine under the action of gravity for hot mixing, and the main shaft speed of the hot mixing machine is controlled at 650 rpm and the temperature is controlled at 170℃. The hot-mixed material flows to the cold mixing machine, and the main shaft speed of the cold mixing machine is 65 rpm and the temperature is 45℃. The stirring time under hot mixing condition is 12 min, and the stirring time under cold mixing condition is 8 min.

[0046] 3, the blended PVC fluid after step 2 is sent to the PVC mixing buffer bin, heated by the granulating main machine, the temperature of the granulating main machine is controlled at 175℃, the extrusion output is controlled at 450 kg / h, and the granulating diameter is controlled at 3.5 mm. The granulating material after cutting is removed by the cyclone separator and the vibrating screen, and the qualified products enter the PVC mixing material finished product bin.

[0047] Example 2

[0048] Example 2 is basically the same as Example 1, except that the composition of the mixture of Example 2 is shown in Table 2:

[0049] Table 2

[0050]

[0051] Example 3

[0052] Example 3 is basically the same as Example 1, except that the composition of the mixture of Example 3 is shown in Table 3:

[0053]

[0054] The rest of the same as example 1 implementation, here no longer tedious.

[0055] Comparative Example 1

[0056] Comparative Example 1 and example 1 the difference lies in, Comparative Example 1 for the preparation of cable sheath PVC-based granules of the mixture of material composition as shown in table 4:

[0057] Table 4

[0058]

[0059] The rest of the same as example 1 implementation, here no longer tedious.

[0060] Comparative Example 2

[0061] Comparative Example 2 and example 1 the difference only lies in, Comparative Example 2 for the preparation of cable sheath PVC-based granules of the mixture of material composition as shown in table 5:

[0062] Table 5

[0063]

[0064] The rest of the same as example 1 implementation, here no longer tedious.

[0065] Comparative Example 3

[0066] Comparative Example 3 and example 1 the difference only lies in, Comparative Example 3 for the preparation of cable sheath PVC-based granules of the mixture of material composition as shown in table 6:

[0067] Table 6

[0068]

[0069] The rest of the same as example 1 implementation, here no longer tedious.

[0070] According to GB / T 8815-2008 (soft polyvinyl chloride plastic for wire and cable) standard, the mechanical properties, processing fluidity and thermal stability of the above-mentioned example, comparative example of cable sheath PVC-based granules are tested, and the test results are shown in table 7.

[0071] Table 7

[0072]

[0073] The present application has found through systematic research that the tensile strength of the cable sheath PVC-based granular material prepared by the method of the present application is above 16 MPa, and the elongation at break is above 218%, reaching the standard value for preparing cable sheaths. Compared with the comparative example using 100% virgin PVC powder, the performance of the cable sheath PVC-based granular material prepared by the present application is comparable, and the toughness is improved to some extent, and the cost can be reduced by more than 30%. In addition, the volume resistivity of the cable sheath PVC-based granular material prepared by the preparation method of the present application is 1.0 x 10 13 The above shows that it has good insulation, which benefits from the fact that the recycled PVC used in the present application decomposes part of the chlorides due to pyrolysis and illumination, thereby achieving certain improvement in the insulation and flame retardance of the granular material; at the same time, the content of impurities in the recycled PVC crushing material, mainly soil, is not high during the preparation of the cable granular material, so that the recycled PVC contains part of the soil, and since the soil itself does not have conductivity (similar to the property of the pottery clay in Comparative Example 1), thereby achieving improvement in insulation.

[0074] In summary, the present application provides a method for preparing a cable sheath PVC-based granular material based on waste PVC mulch, which can reduce the raw material cost for preparing cable sheaths by more than 30% through resource utilization of waste PVC, combined with a composite stabilizer and an efficient blending process, and the prepared PVC-based granular material has good mechanical properties and processing fluidity, and the lead-free and environmentally friendly formula meets the requirements of green manufacturing, and has the advantages of high cost performance and low carbon emission.

[0075] In addition, the present inventors have also conducted tests with other raw materials, process operations and process conditions described in the present specification based on the foregoing examples, and all have obtained relatively ideal results.

[0076] The aspects, embodiments, features and examples of the present application should be considered illustrative, for the purpose of explanation, illustration and description, but not for the purpose of limiting the present application, the scope of which is defined only by the claims.

[0077] Although the present application has been described with reference to the illustrative embodiments, it should be understood that various changes, omissions and / or additions can be made without departing from the spirit and scope of the present application, and elements in the embodiments can be substituted with substantially equivalent elements. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present application without departing from the scope thereof. Therefore, the present application is not intended to be limited to the particular embodiments disclosed, but is intended to encompass all embodiments falling within the scope of the appended claims. Furthermore, unless specifically stated, any use of the terms first, second, etc. does not indicate any order or importance, but is used for the purpose of distinguishing one element from another.

Claims

1. A process for the production of PVC-based granules for cable sheaths, characterized in that, The application relates to a PVC-based granular material for cable sheath. The PVC-based granular material is prepared by mixing 30-50wt% of recycled PVC broken material and 50-70wt% of virgin PVC powder at 60-80 DEG C to form a PVC resin, and then blending and extruding and granulating a mixture containing 100 parts by mass of the PVC resin, 20-40 parts by mass of a plasticizer, 10-15 parts by mass of a stabilizer, 20-25 parts by mass of a filler and 1.0-1.8 parts by mass of a lubricant. The average polymerization degree of the virgin PVC powder is 1250-1350; 2. The method of claim 1, wherein: And / or, the particle size of the PVC resin is 3-5mm; And / or, the plasticizer comprises at least one of a general plasticizer, a heat-stable plasticizer and / or a flame-retardant plasticizer; And / or, the stabilizer comprises at least one of organic tin, calcium-zinc stabilizer or calcium stearate; And / or, the filler comprises calcium carbonate. The general plasticizer comprises one or a combination of dioctyl phthalate, dinonyl phthalate, dioctyl terephthalate and trioctyl trimellitate; the heat-stable and / or flame-retardant plasticizer comprises one or a combination of epoxide compounds, phosphate compounds and halogenated hydrocarbon compounds; 3. The method of claim 2, wherein: And / or, the plasticizer comprises the general plasticizer and the heat-stable and / or flame-retardant plasticizer, and the mass ratio of the general plasticizer to the heat-stable and / or flame-retardant plasticizer is 1:0.1-0.2; And / or, the stabilizer comprises organic tin and calcium stearate with a mass ratio of 1:0.1-0.2, or the stabilizer comprises calcium-zinc stabilizer and calcium stearate with a mass ratio of 1:0.1-0.2; And / or, the lubricant comprises polyethylene wax and / or chlorinated paraffin, oxidized polyethylene and a lipid substance, and the lipid substance comprises one or a combination of epoxidized soybean oil, glycerol and monoglyceride, and the mass ratio of the polyethylene wax to the chlorinated paraffin to the oxidized polyethylene to the lipid substance is 1:0.1-0.3:1-3. The mixture further comprises 50-60 parts by mass of an auxiliary agent, and the auxiliary agent comprises a flame retardant and / or a colorant.

4. The method of claim 1, wherein: The auxiliary agent comprises the flame retardant and the colorant with a mass ratio of 1:0.03-0.

04.

5. The method of claim 4, wherein: The source of the recycled PVC broken material comprises: sequentially washing, crushing and rubbing and dehydrating the collected waste PVC mulch to obtain the recycled PVC broken material.

6. The method of claim 1, wherein: The washing is mechanical washing, which comprises cutting and separating the collected waste PVC mulch and then dry cleaning the waste PVC mulch; 7. The method of claim 6, wherein: And / or, the crushing and rubbing comprises crushing the waste PVC mulch after the washing, and then rubbing the crushed waste PVC mulch at a high speed under the condition of 1500-2200 rpm; And / or, the dehydrating comprises rinsing the waste PVC mulch after the crushing and rubbing, and then dehydrating the waste PVC mulch, and the mixture is prepared after the dehydration rate reaches 98% or above. The blending comprises: first hot mixing at 150-180 DEG C for 10-15 min, and then cold mixing at 40-50 DEG C for 5-10 min; 8. The method of claim 1, wherein: And / or, the temperature of the extruding and granulating is 170-180 DEG C. ​ 9. A PVC-based granulate for cable sheaths, characterized in that It is produced by the production process according to any one of claims 1 to 8.

10. Use of the PVC-based granules for cable sheaths according to claim 9 for the production of cable sheaths.

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