CN111875806A - Application of Ziegler-Natta catalyst, method for preparing cable plant flexible joint and insulating layer thereof, and cable plant flexible joint - Google Patents
Application of Ziegler-Natta catalyst, method for preparing cable plant flexible joint and insulating layer thereof, and cable plant flexible joint Download PDFInfo
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- CN111875806A CN111875806A CN202010754335.8A CN202010754335A CN111875806A CN 111875806 A CN111875806 A CN 111875806A CN 202010754335 A CN202010754335 A CN 202010754335A CN 111875806 A CN111875806 A CN 111875806A
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G81/00—Macromolecular compounds obtained by interreacting polymers in the absence of monomers, e.g. block polymers
- C08G81/02—Macromolecular compounds obtained by interreacting polymers in the absence of monomers, e.g. block polymers at least one of the polymers being obtained by reactions involving only carbon-to-carbon unsaturated bonds
- C08G81/021—Block or graft polymers containing only sequences of polymers of C08C or C08F
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- H—ELECTRICITY
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- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R43/00—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors
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Abstract
The invention relates to an application of a Ziegler-Natta catalyst in copolymerization of crosslinked polyethylene and polypropylene, a method for preparing a cable plant flexible joint and an insulating layer thereof, and a method for preparing a cable plant flexible joint. The Ziegler-Natta catalyst can initiate the reaction of polyethylene and polypropylene to synthesize high molecular weight PE-b-PP copolymer, and can accurately control the length of the copolymerization block, so that the obtained copolymer has excellent mechanical properties.
Description
Technical Field
The invention relates to the field of power cable accessories, in particular to application of a Ziegler-Natta catalyst, a method for preparing a cable factory soft joint and an insulating layer thereof, and a method for preparing a cable factory soft joint.
Background
An extruded cable using cross-linked polyethylene (XLPE) as a main insulating material is widely used in power systems due to its advantages of simple structure, large transmission capacity, light weight, simple and convenient installation and maintenance, low processing and manufacturing costs, stable operation, etc. Various types of cable accessories are required to make electrical connections between cables and primary electrical equipment to optimize the insulating interface fit between the cables and other components (including other cables) and to dissipate the electric field stress concentration distortions caused by stripping the outer semiconductive shield from the cables. The cable accessories interconnected between the power cables are called cable intermediate joints or cable couplings.
The cable intermediate joint is divided into an integral prefabricated type, a combined prefabricated type and a factory soft joint which is mainly manufactured in a cable factory or on site according to different structural forms of the cable intermediate joint. The main difference between the factory soft joint and the former two is that the factory soft joint mainly adopts the insulating material and the semi-conductive shielding material which are the same as or close to the cable body as the structural material, the manufacturing process is similar to the extrusion process of the cable body, and the external dimension after the manufacturing is nearly the same as the cable body.
In the existing process for manufacturing a factory flexible joint of a crosslinked cable, an insulating layer is mainly manufactured by adopting an injection welding technology for welding, and a melting injection molding extruder, a cladding mold which is almost equal in diameter with a cable core layer (within a cable outer shielding layer) and the like are mainly required on a tool. Because the insulation material of the common extruded cable is a cross-linked polyethylene material, a cross-linking agent is required to be doped in the polyethylene insulation material to complete a cross-linking reaction when the soft joint is used for manufacturing insulation, so that an insulation structure equivalent to cable insulation is finally formed. However, the air inside the mold is coated, and the crosslinking by-products generated during the crosslinking by recovering the insulation are difficult to discharge in the soft joint insulating material, so that the defects of bubbles, impurities and the like are easily formed.
In the traditional chemical materials, similar to the crosslinked polyethylene material, the polypropylene material also has the advantages of high dielectric strength, good insulating property, good heat resistance, equivalent mechanical strength and the like. However, polyethylene and polypropylene, despite having similar hydrocarbon compositions, are incompatible with each other, so that in the case of conventional means, there is always an interface between the cable insulation and the intermediate flexible joint, which are produced using these two materials separately, and finally insulation failure occurs due to interfacial breakdown.
Disclosure of Invention
Therefore, the technical problem to be solved by the present invention is to overcome the defects of the prior art that the interface always exists when the soft joint of the factory is prepared by using polyethylene and polypropylene, thereby providing an application of using the Ziegler-Natta catalyst in the copolymerization of polyethylene and polypropylene.
The invention also provides a method for preparing the soft joint insulating layer in the cable factory.
The invention also provides a method for preparing the soft joint of the cable factory.
The invention also provides a flexible joint for a cable factory.
Therefore, the invention provides an application of the Ziegler-Natta catalyst in the copolymerization of crosslinked polyethylene and polypropylene.
Currently, the vast majority of Polyethylene (PE) and polypropylene (PP) preparations employ heterogeneous chromium and titanium catalysts. Heterogeneous olefin polymerization catalysts have many active sites, each molecule having its own reactivity difference, resulting in polymers of different Molecular Weights (MW), molecular weight distributions and microstructures. In the case of polyethylene and polypropylene, these differences and phase separation inhibit interfacial adhesion and reduce the mechanical properties of the melt blend. In order to solve the problem of the compatibility of polypropylene and polyethylene, a Ziegler-Natta catalyst is found to be used as a polymerization initiator for synthesizing PE-b-PP copolymer with high molecular weight, and the length of a copolymerization block can be accurately controlled. The resulting block amorphous copolymer can act as an additive, thereby increasing the compatibility of the polyethylene and polypropylene.
Further, the catalyst is TiCl4-Al(C2H5)3And/or TiCl4-Al(C2H5)2Cl。
The chemical reaction principle is as follows.
Alkylation:
TiCl4+AlR3→RTiCl3+AlR2Cl
TiCl4+AlR2Cl→RTiCl3+AlRCl2
RTiCl3+AlR3→R2TiCl2+AlR2Cl
homolytic cleavage and reduction of titanium alkyls:
RTiCl3→TiCl3+R·
R2TiCl2→RTiCl2+R·
TiCl4+R·→TiCl3+RCl
termination of free radicals:
2R → end of coupling or disproportionation.
The invention also provides a method for preparing the soft joint insulating layer in the cable factory, which comprises the following steps:
s1, peeling the cross-linked polyethylene insulating layer covering the conductor at the connection position of the factory soft joint into a slope and exposing the inner semi-conductive shielding layer and a section of conductor;
s2, connecting the exposed conductor and recovering the inner semi-conductive shielding layer;
s3, winding a catalyst material belt made of Ziegler-Natta catalyst and polypropylene and/or polyethylene on the insulating layer of the slope;
s4, exhausting all air at the insulating layer wound by the catalyst material strip, and heating the insulating layer;
and S5, extruding polypropylene into the insulating layer wound by the catalyst material tape, melting and copolymerizing the polypropylene and the crosslinked polyethylene, and cooling after the reaction is finished to change the reaction part into a solid state.
Further, the catalyst material belt is prepared by the following method: the ziegler-natta catalyst is mixed with polyethylene or polypropylene and then extruded into a ribbon of catalyst material.
Furthermore, the included angle between the insulating layer of the slope surface and the conductor is 25-40 degrees.
Furthermore, the method also comprises the step of carrying out surface deoxidation and waterproof treatment on the exposed conductor before the conductor is connected.
Further, the inner semiconductive shield layer is recovered with the semiconductive shield tape in step S2.
Further, before winding the catalyst material belt on the insulating layer of the slope surface, the method also comprises the step of grinding the insulating layer of the slope surface into a rough surface.
Further, in step S4, the air is purged with an inert gas or nitrogen, and the temperature is heated to 180 ℃ to 240 ℃.
Further, in step S5, after the reaction part becomes solid, the reaction part is continuously exposed to an inert gas or nitrogen atmosphere for 24 to 36 hours.
The invention also provides a method for preparing the soft joint of the cable factory, which comprises the following steps:
preparing the insulating layer of the flexible joint of the cable factory according to the method;
restoring the outer semiconductive shield layer;
the metal shielding layer, the buffer layer and the outer sheath are recovered.
The invention also provides the cable factory soft joint prepared by the method.
The technical scheme of the invention has the following advantages:
1. the Ziegler-Natta catalyst can initiate the reaction of polyethylene and polypropylene to synthesize PE-b-PP copolymer with high molecular weight, and can accurately control the length of a copolymerization block, so that the obtained copolymer has excellent mechanical properties.
2. According to the method for preparing the insulating layer of the flexible joint in the cable plant, provided by the invention, the polypropylene material and the polyethylene material are copolymerized in a molten state by using the Ziegler-Natta catalyst, so that the interface between the new insulating material and the old insulating material in the manufacturing process of the flexible joint in the plant can be effectively eliminated, the success rate and the reliability of manufacturing the flexible joint in the plant are directly improved, and the purpose of realizing all functions of the flexible joint in the plant without using a crosslinking reaction is achieved. Because the polyethylene main body material does not need to exhaust in the melting recovery process, only a small amount of exhaust or impurity removal forms exist in the copolymerization area of the polyethylene main body material and the polypropylene material, the manufacturing time of the power cable factory soft joint can be greatly shortened, and the reliability of the factory soft joint can be greatly improved.
3. According to the method for preparing the insulating layer of the flexible joint in the cable plant, the catalyst for the copolymerization reaction of the polypropylene and the polyethylene is accurately placed at the position needing the copolymerization reaction by winding the insulating material base band containing the catalyst, the original crosslinked polyethylene is subjected to decrosslinking by heating the whole material, and the copolymerization reaction is completed with the polypropylene under the action of the catalyst, so that the obtained whole joint does not contain an obvious interface of the polyethylene and the polypropylene any more, and the effect of recovering the whole cable body is achieved.
4. According to the method for preparing the insulating layer of the soft joint in the cable factory, the exposed conductor is subjected to surface deoxidation and waterproof treatment before being connected with the conductor, so that impurities can be contained as little as possible when the conductor is recovered, the problem of heating of the conductor joint caused by poor contact of the conductor or reduction of conductivity at the conductor joint is prevented, and the reliability of conductor connection can be effectively ensured; the insulating layer on the slope surface is polished to be a rough surface, so that the contact between the insulating layer and the catalyst material belt can be increased, the fusion between the catalyst material belt and the cross-linked polyethylene in the reaction process is facilitated, and the reaction is promoted.
5. The method for preparing the insulating layer of the soft joint in the cable plant, provided by the invention, comprises the step of heating the temperature in step S4 to 180-240 ℃, wherein the temperature is the suitable melt polymerization reaction temperature of the polypropylene and the crosslinked polyethylene, and the PE-b-PP copolymer with high molecular weight can be generated in the temperature range.
6. According to the method for preparing the insulating layer of the flexible joint in the cable plant, after the reaction part is changed into the solid state, the reaction part is continuously in the inert gas environment for 24-36 hours, so that the impurities generated in the process of melt copolymerization can be discharged.
7. The flexible joint prepared by the method for preparing the flexible joint of the cable factory is applied to various voltage levels and has no relation with the alternating current or direct current property of a power system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a cross-sectional view of a cable in embodiment 1 of the present invention;
FIG. 2 is a schematic structural view of the cable treated in step 3) in example 1 of the present invention;
FIG. 3 is a schematic structural diagram of a cable after conductors are connected in step 5) in example 1 of the present invention;
FIG. 4 is a schematic structural diagram of the cable after the inner semiconductive shielding layer is recovered in step 6) of example 1 of the present invention;
fig. 5 is a schematic view of the cable structure after a new insulating layer is formed in step 13) of example 1 of the present invention.
Reference numerals:
1. a conductor; 2. an inner semiconductor shield layer; 3. a crosslinked polyethylene insulating layer; 4. an outer semiconductor shield layer; 5. a metal shielding layer; 6. a buffer layer; 7. an outer sheath; 8. a semiconductive shield tape; 9. and a polypropylene insulating layer.
Detailed Description
The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.
The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.
Example 1
A method of making a cable plant flexible joint, comprising the steps of:
1) TiCl Ziegler-Natta catalyst4-Al(C2H5)3The (granular) and polyethylene are fully mixed according to the mass ratio of 1:1, and the catalyst material belt with the width of about 4cm and the thickness of about 2mm is prepared on a plane extruder by using a one-way pultrusion mode.
2) Heating and straightening the connection position of a factory soft joint of an extruded insulated power cable, wherein the cross section of the cable is shown in figure 1 and comprises a conductor 1, an inner semiconductor shielding layer 2, a crosslinked polyethylene insulating layer 3, an outer semiconductor shielding layer 4, a metal shielding layer 5, a buffer layer 6 and an outer sheath 7;
3) removing part of the outer sheath 7, the buffer layer 6, the metal shielding layer 5, the outer semi-conductive shielding layer 4, the crosslinked polyethylene insulating layer 3 and the inner semi-conductive shielding layer 2 of the straightened cable until a section of conductor 1 is exposed, peeling the crosslinked polyethylene insulating layer 3 into a slope surface with an included angle of 35 degrees with the conductor by using a peeling tool, and exposing the inner semi-conductive shielding layer with the thickness of 20mm (commonly called as manufacturing a soft joint pencil head of a cable core), wherein the section of the treated cable is shown in figure 2 (only part of the structure is marked in the figure);
4) polishing the crosslinked polyethylene insulating layer 3 on the slope surface into a rough surface;
5) carrying out surface deoxidation and waterproof treatment on the exposed conductor 1, connecting the exposed conductors 1 in the two cables in a bolt connection mode, and treating the connected conductors 1 until the surfaces are smooth and burr-free, wherein the connected cables are shown in figure 3;
6) restoring the inner semi-conductive shielding layer 2 by using the semi-conductive shielding tape 8 with the same material as the inner semi-conductive shielding layer 2, wherein the cable with the restored inner semi-conductive shielding layer 2 is shown in FIG. 4;
7) winding a catalyst material strip on the cross-linked polyethylene insulating layer 3 with the slope surfaces at two sides, wherein when winding, starting from the bottom of the slope surface, the subsequent catalyst material strip is overlapped with the previous catalyst material strip by half of the width, and winding sequentially until the catalyst material strip is wound to the top end of the slope surface, and at the moment, no residual air gap or air bubble exists on the winding contact surface;
8) fixing a factory soft connector mould on the connected cable, placing the connection position of the factory soft connector in the middle of the factory soft connector mould, closing the factory soft connector mould, connecting a nitrogen closed loop, introducing nitrogen with 2 atmospheric pressures, and ensuring that the connection insulation recovery position of the factory soft connector, namely all air at the insulation layer wound by the catalyst material strip, is exhausted;
9) heating the cable connecting section at the position of the mould to 210 ℃;
10) extruding polypropylene at the temperature of 210 ℃ into a factory soft joint die by using a small extruder until the polypropylene is discharged from a gas outlet of the factory soft joint die, and maintaining the temperature in the factory soft joint die at 210 ℃;
11) waiting for 2 hours until the melt copolymerization reaction of the polypropylene and the crosslinked polyethylene is finished;
12) naturally cooling to normal temperature after the melting reaction is finished, and continuously waiting for 30 hours after the reaction part becomes solid;
13) dismantling a factory soft joint die, processing the surface of the newly extruded insulating material to the required surface cleanliness, wiping the surface of the insulating material clean by using materials such as alcohol cloth, wherein the processed cable is shown in figure 5 (only part of the structure is marked in the figure), and comprises a newly formed polypropylene insulating layer 9, and the contact part of the polypropylene insulating layer 9 and the crosslinked polyethylene insulating layer 3 is a copolymerized polyethylene-polypropylene copolymer;
14) restoring the outer semiconductive shield layer 4 using a semiconductive shield tape;
15) the metal shielding layer 5, the buffer layer 6 and the outer sheath 7 of the recovery cable.
The prepared factory soft joint is planed along the direction vertical to the conductor, the contact part of the original crosslinked polyethylene insulating layer of the cable and the newly formed polypropylene insulating layer is observed to have no oblique line boundary between new and old insulating materials, and the non-interface transition between the crosslinked polyethylene material of the cable body and the polypropylene insulating material of the intermediate joint is completely realized.
Example 2
A method of making a cable plant flexible joint, comprising the steps of:
1) TiCl Ziegler-Natta catalyst4-Al(C2H5)2Cl (granular) and polypropylene are fully mixed according to the proportion of 1:1, and the catalyst material belt with the width of about 4cm and the thickness of about 2mm is prepared on a plane extruder by a unidirectional pultrusion mode.
2) Heating and straightening the connection position of a factory soft joint of the extruded insulated power cable;
3) removing part of the outer sheath, the buffer layer, the metal shielding layer, the outer semi-conductive shielding layer, the crosslinked polyethylene insulating layer and the inner semi-conductive shielding layer of the straightened cable until a section of conductor is exposed, peeling the insulating layer into a slope surface with an included angle of 25 degrees with the conductor by using a peeling tool, and exposing the inner semi-conductive shielding layer with the included angle of 20mm (commonly called to manufacture a soft joint pencil stub of a cable core);
4) polishing the crosslinked polyethylene insulating layer of the slope surface into a rough surface;
5) carrying out surface deoxidation and waterproof treatment on the exposed conductor, connecting the exposed conductors in the two cables in a welding connection mode, and treating the connected conductors until the surfaces are smooth and have no burrs;
6) restoring the inner semiconductive shield layer using semiconductive shield tape conforming to the material of the inner semiconductive shield layer;
7) winding a catalyst material strip on the cross-linked polyethylene insulating layers with the two sides presenting the slope surfaces, wherein when winding, starting from the bottom of the slope surface, the subsequent catalyst material strip is overlapped with the previous material strip by half of the width, and is wound in sequence until the catalyst material strip is wound to the top end of the slope surface, and at the moment, the winding contact surface is kept to have no residual air gaps or air bubbles;
8) fixing a factory soft connector mould on the connected cable, placing the connection position of the factory soft connector in the middle of the factory soft connector mould, closing the factory soft connector mould, connecting a nitrogen closed loop, introducing nitrogen with 2 atmospheric pressures, and ensuring that the connection insulation recovery position of the factory soft connector, namely all air at the insulation layer wound by the catalyst material strip, is exhausted;
9) heating the cable connecting section at the position of the mould to 180 ℃;
10) extruding polypropylene at 180 ℃ into a factory soft joint die by using a small extruder until the polypropylene is discharged from a gas outlet of the factory soft joint die, and maintaining the temperature in the factory soft joint die at 180 ℃;
11) waiting for 2 hours until the melt copolymerization reaction of the polypropylene and the crosslinked polyethylene is finished;
12) naturally cooling to normal temperature after the melting reaction is finished, and continuously waiting for 24 hours after the reaction part becomes solid;
13) removing a factory soft joint mould, treating the surface of the newly extruded insulating material to required surface cleanliness, wiping the surface of the insulating material clean by using materials such as alcohol cloth and the like, wherein the treated cable soft joint comprises a newly formed polypropylene insulating layer, and the contact part of the polypropylene insulating layer and the crosslinked polyethylene insulating layer is a copolymerized polyethylene-polypropylene copolymer;
14) restoring the outer semiconductive shield layer using a semiconductive shield tape;
15) the metal shielding layer, the buffer layer and the outer sheath of the recovery cable.
The prepared factory soft joint is planed along the direction vertical to the conductor, the contact part of the original crosslinked polyethylene insulating layer of the cable and the newly formed polypropylene insulating layer is observed to have no oblique line boundary between new and old insulating materials, and the non-interface transition between the crosslinked polyethylene material of the cable body and the polypropylene insulating material of the intermediate joint is completely realized.
Example 3
A method of making a cable plant flexible joint, comprising the steps of:
1) TiCl Ziegler-Natta catalyst4-Al(C2H5)2Cl (granular) and polypropylene are fully mixed according to the proportion of 1:1, and the catalyst material belt with the width of about 4cm and the thickness of about 2mm is prepared on a plane extruder by a unidirectional pultrusion mode.
2) Heating and straightening the connection position of a factory soft joint of the extruded insulated power cable;
3) removing part of the outer sheath, the buffer layer, the metal shielding layer, the outer semi-conductive shielding layer, the crosslinked polyethylene insulating layer and the semi-conductive shielding layer of the straightened cable until a section of conductor is exposed, peeling the insulating layer into a slope surface with an included angle of 45 degrees with the conductor by using a peeling tool, and exposing an inner semi-conductive shielding layer with the thickness of 20mm (commonly called to manufacture a soft joint pencil stub of a cable core);
4) polishing the crosslinked polyethylene insulating layer of the slope surface into a rough surface;
5) carrying out surface deoxidation and waterproof treatment on the exposed conductor, connecting the exposed conductors in the two cables in a welding connection mode, and treating the connected conductors until the surfaces are smooth and have no burrs;
6) restoring the inner semiconductive shield layer using semiconductive shield tape conforming to the material of the inner semiconductive shield layer;
7) winding a catalyst material strip on the cross-linked polyethylene insulating layers with the two sides presenting the slope surfaces, wherein when winding, starting from the bottom of the slope surface, the subsequent catalyst material strip is overlapped with the previous material strip by half of the width, and is wound in sequence until the catalyst material strip is wound to the top end of the slope surface, and at the moment, the winding contact surface is kept to have no residual air gaps or air bubbles;
8) fixing a factory soft connector mould on the connected cable, placing the connection position of the factory soft connector in the middle of the factory soft connector mould, closing the factory soft connector mould, connecting a nitrogen closed loop, introducing nitrogen with 2 atmospheric pressures, and ensuring that the connection insulation recovery position of the factory soft connector, namely all air at the insulation layer wound by the catalyst material strip, is exhausted;
9) heating the cable connecting section at the position of the mould to 240 ℃;
10) extruding polypropylene at 240 ℃ into a factory soft joint die by using a small extruder until the polypropylene is discharged from a gas outlet of the factory soft joint die, and maintaining the temperature in the factory soft joint die at 240 ℃;
11) waiting for 2 hours until the melt copolymerization reaction of the polypropylene and the crosslinked polyethylene is finished;
12) naturally cooling to normal temperature after the melting reaction is finished, and continuously waiting for 36 hours after the reaction part becomes solid;
13) removing a factory soft joint mould, treating the surface of the newly extruded insulating material to required surface cleanliness, wiping the surface of the insulating material clean by using materials such as alcohol cloth and the like, wherein the treated cable soft joint comprises a newly formed polypropylene insulating layer, and the contact part of the polypropylene insulating layer and the crosslinked polyethylene insulating layer is a copolymerized polyethylene-polypropylene copolymer;
14) restoring the outer semiconductive shield layer using a semiconductive shield tape;
15) the metal shielding layer, the buffer layer and the outer sheath of the recovery cable.
The prepared factory soft joint is planed along the direction vertical to the conductor, the contact part of the original crosslinked polyethylene insulating layer of the cable and the newly formed polypropylene insulating layer is observed to have no oblique line boundary between new and old insulating materials, and the non-interface transition between the crosslinked polyethylene material of the cable body and the polypropylene insulating material of the intermediate joint is completely realized.
Example 4
Preparing a polypropylene film with the thickness of 0.5mm and the diameter of 150mm by using polypropylene particles at 160 ℃;
using polyethylene particles with TiCl4-Al(C2H5)3(granular) mixing according to the mass ratio of 1:1, and preparing a catalyst film with the thickness of 0.5mm and the diameter of 150mm at 170 ℃;
preparing a polyethylene film with the thickness of 0.5mm and the diameter of 150mm by using polyethylene particles at 160 ℃;
the polypropylene film, the polyethylene film and the catalyst film are overlapped together according to the sequence of polyethylene (down) -catalyst (middle) -polypropylene (up), hot-pressed and bonded at 180 ℃, and cooled to room temperature after heat preservation for 2 hours.
Comparative example 1
A polypropylene film and a polyethylene film were produced in the same manner as in example 4, and they were laminated in the order of polyethylene (bottom) -polypropylene (top), heat-pressure bonded at 180 ℃ for 2 hours, and then cooled to room temperature.
Examples of the experiments
The bonded films prepared in example 4 and comparative example 1 were subjected to a tensile test as follows:
the method comprises the following steps of taking a bonded film, slightly cutting a small opening with the length and the depth of 1cm at the edge along a bonding interface by using a sharp slice blade, respectively perforating corresponding positions on the two cut films, respectively using a T-shaped hook to penetrate through the hole from inside to outside, clamping a cross beam of the T-shaped hook on the hole, and fixing the two hooks on an upper clamp and a lower clamp of a tensile tester. The punched position was examined for damage such as cracking.
The two hooks were slowly stretched using a tensile tester, slowly tearing the two films that were bonded. The tensile force was recorded. The test was repeated 3 times.
The experimental results are as follows:
the adhesive film of comparative example 1 had a tear extension of 0.9 to 1.1N.
The adhesive poly film of example 4 was stretched at 5-8N.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (12)
1. Use of a ziegler-natta catalyst in the copolymerisation of crosslinked polyethylene and polypropylene.
2. Use of a ziegler-natta catalyst according to claim 1 for the copolymerization of polyethylene and polypropylene, wherein said catalyst is TiCl4-Al(C2H5)3And/or TiCl4-Al(C2H5)2Cl。
3. A method for preparing a soft joint insulating layer in a cable factory is characterized by comprising the following steps:
s1, peeling the cross-linked polyethylene insulating layer covering the conductor at the connection position of the factory soft joint into a slope and exposing the inner semi-conductive shielding layer and a section of conductor;
s2, connecting the exposed conductor and recovering the inner semi-conductive shielding layer;
s3, winding a catalyst material belt made of Ziegler-Natta catalyst and polypropylene and/or polyethylene on the insulating layer of the slope;
s4, exhausting all air at the insulating layer wound by the catalyst material strip, and heating the insulating layer;
and S5, extruding polypropylene into the insulating layer wound by the catalyst material tape, melting and copolymerizing the polypropylene and the crosslinked polyethylene, and cooling after the reaction is finished to change the reaction part into a solid state.
4. A method for preparing an insulating layer for a flexible joint in a cable plant according to claim 3, characterized in that the catalyst material tape is prepared by: the ziegler-natta catalyst is mixed with polyethylene or polypropylene and then extruded into a ribbon of catalyst material.
5. The method for preparing the insulation layer of the flexible joint in the cable factory as claimed in claim 3 or 4, wherein the angle between the insulation layer of the slope and the conductor is 25-40 °.
6. The method for preparing the insulation layer of the flexible joint in the cable factory according to any one of claims 3 to 5, wherein the step of surface-deoxidizing and waterproofing the bare conductor is further included before the conductor is connected.
7. The method for preparing an insulation layer for a flexible joint in a cable plant according to any one of claims 3 to 6, wherein the inner semiconductive shield layer is restored with a semiconductive shield tape in step S2.
8. The method of making a cable plant flexible joint insulation according to any one of claims 3 to 7, further comprising the step of grinding the insulation layer of the ramp to a matt surface prior to winding the strip of catalyst material on the insulation layer of the ramp.
9. The method for preparing an insulation layer for a flexible joint in a cable plant according to any one of claims 3 to 8, wherein the air is exhausted with inert gas or nitrogen gas and heated to 180 to 240 ℃ in step S4.
10. The method for preparing an insulation layer for a flexible joint in a cable plant according to any one of claims 3 to 9, wherein the reaction part is changed to a solid state and then is continuously exposed to an inert gas or nitrogen atmosphere for 24 to 36 hours in step S5.
11. A method of making a cable plant flexible joint, comprising the steps of:
preparing a cable plant flexible joint insulation according to the method of any one of claims 3-10;
restoring the outer semiconductive shield layer;
the metal shielding layer, the buffer layer and the outer sheath are recovered.
12. A cable plant flexible joint prepared by the method of claim 11.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112234532A (en) * | 2020-11-04 | 2021-01-15 | 广东电网有限责任公司广州供电局 | Polypropylene 220kV molded cable connector and manufacturing method thereof |
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