Method for improving interface bonding strength of ultra-smooth semiconductor shielding layer

Abstract

This invention discloses a method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer. The method involves grafting and modifying the surface of conductive carbon black with an acid ester, then dividing it into two portions. The two portions of modified conductive carbon black are separately mixed with EVA resin and polyimide, and then separately vulcanized in a flat vulcanizing machine. The vulcanized materials are then added to a Banbury mixer along with vinylpyrrolidone, NN'-ethylene bis-stearamide, polyethyleneimine, and sodium polyacrylate for compounding. The compounded material is immediately impregnated with peroxide and then rapidly fed into an extruder. After extrusion, it is vulcanized again to obtain an ultra-smooth semiconductor shielding layer with improved interfacial bonding strength. This invention modifies the surface of conductive carbon black, strengthening the interaction between the macromolecular chains and the carbon black. Batch mixing with different esters enhances its internal anisotropy, forming attractive clusters, reducing the dispersion of conductive carbon black within the shielding layer, decreasing the number of branches, reducing repulsion, and ultimately strengthening the interfacial bonding strength, resulting in a better overall shielding layer.

Description

Technical Field

[0001] This invention relates to the field of semiconductor shielding technology, and more specifically, to a method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer. Background Technology

[0002] Semiconducting shielding is a crucial component of medium- and high-voltage cable structures. It ensures a more uniform electric field distribution within the cable, reducing stress concentration and its impact on cable insulation. The quality of the semiconducting shielding material directly affects the cable's safety and service life.

[0003] For example, application number 202510572520.8 discloses a melt blending preparation process for semi-conductive shielding material for ultra-high voltage cross-linked polyethylene cables. By synergistic compounding of plasma surface-modified carbon black and carbon nanotubes, combined with a staged feeding process, the conductive filler is directionally dispersed to form a three-dimensional interpenetrating conductive network, which significantly improves the local electric field homogenization capability of ultra-high voltage cables.

[0004] However, this process only improves the local electric field homogenization capability of the cable. Although it achieves the directional dispersion of conductive fillers and the volume resistivity is not significantly reduced, the modification and dispersion of carbon black leads to a decrease in the interfacial bonding strength of the original semiconductor shielding layer. This results in a decrease in the overall structural strength of the high-voltage cable, making it more prone to disintegration and reducing the surface smoothness. The mechanical properties are significantly reduced, only near the qualified line standard. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for improving the interface bonding strength of an ultra-smooth semiconductor shielding layer, thereby solving one or more of the above-mentioned problems.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer involves grafting and modifying the surface of conductive carbon black with an acid ester and then dividing it into two parts. Two portions of modified conductive carbon black were mixed evenly with EVA resin and polyimide, respectively, and then sent to a flat vulcanizing machine for vulcanization. The vulcanized material, along with vinylpyrrolidone, NN'-ethylene bis-stearamide, polyethyleneimine, and sodium polyacrylate, is added to a mixer and mixed. The mixed material is immediately wetted with peroxide and then quickly fed into an extruder. After extrusion, it is vulcanized again to obtain an ultra-smooth semiconductor shielding layer with improved interfacial bonding strength.

[0007] Furthermore, the ester used for modifying conductive carbon black is maleic anhydride. After washing the conductive carbon black with alkali, nitric acid and maleic anhydride are added. Cerium nitrate ammonium is added under nitrogen protection and the mixture is heated to react. After the reaction is completed, the carbon black is washed with water and filtered to obtain the surface-grafted ester modified conductive carbon black.

[0008] Furthermore, the modified conductive carbon black was divided into two parts in a 7:3 ratio, with 70% of the modified conductive carbon black being mixed with EVA resin and 30% of the modified conductive carbon black being mixed with polyimide.

[0009] Further, the stirred modified conductive carbon black and EVA resin were added to the dispersant and silane coupling agent, and evenly spread in the mold cavity. The mixture was then hot-pressed at 160°C and 10MPa for 15 minutes. The stirred modified conductive carbon black and polyimide were added to the lubricant and antioxidant, and spread evenly in the cavity. The mixture was then hot-pressed at 160℃ and 10MPa for 10 minutes. After vulcanization, the two batches of material were kept under pressure and cooled to room temperature before being removed.

[0010] Furthermore, the dispersant is polyacrylic acid or polycarboxylate; The lubricant is perfluoropolyether oil or silica mineral oil; The antioxidant is 2,6-di-tert-butyl-4-methylphenol or 4,4'-thiobis(6-tert-butyl-3-methylphenol).

[0011] Furthermore, the mixing temperature in the internal mixer is 90~120℃, and the mixing time is 8~15min.

[0012] Furthermore, the selected peroxide is dicumyl peroxide or di-tert-butyl peroxide; The soaking time should be controlled within 12 seconds.

[0013] Furthermore, the extruder is set with four temperature zones of 120, 135, 140 and 150°C in sequence, and the extrusion speed is 100~120 r / min.

[0014] Furthermore, the extruded material is dried after being cooled with water and then sent back to the vulcanizing machine for vulcanization, where it is hot-pressed for 15 minutes at 180°C and 10MPa pressure.

[0015] Furthermore, the treatment of the mixed material before it is fed into the extruder is achieved by replacing the wetting method with atomization contact, with the atomization temperature maintained at 65℃ and the atomization time not exceeding 45s.

[0016] In summary, the present invention has the following beneficial effects: by modifying conductive carbon black and grafting esters onto its surface, the compatibility with other formulations is improved, and the covalent bond between it and the two esters is deepened, which is beneficial to strengthening the interfacial bonding strength and improving the surface smoothness of the composite shielding layer; mixing with different esters in batches is to enhance anisotropy, forming attractive clusters between the two batches of materials, avoiding severe phase separation of a single object, while actually increasing the content of conductive carbon black, strengthening the interaction between macromolecular chains and carbon black, and making the interfacial bonding tighter; selecting appropriate initiators improves the dispersibility of conductive carbon black in different aggregates, reduces the number of branches formed overall, improves the repulsion phenomenon, and endows the shielding layer with microscopic dynamic rheological properties, taking into account both texture and stability. Attached Figure Description

[0017] Figure 1 This is a complete process flow diagram of one embodiment provided by the present invention. Detailed Implementation Example

[0018] A method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer, such as Figure 1 As shown, the conductive carbon black surface is first grafted and modified using an acid ester, preferably maleic anhydride. Specifically, the conductive carbon black is washed with a solvent prepared with baking soda. The amount of baking soda is not critical; its purpose is to remove unnecessary impurities and activate the functional groups within the conductive carbon black. The sulfur content of the conductive carbon black must be less than 0.02%, and the residue on a 325-mesh sieve must be less than 2 ppm. This method yields nanoscale conductive carbon black with excellent dispersion stability and facilitates rapid activation of functional groups. Using 10a as the mass fraction of the conductive carbon black, the alkaline-washed conductive carbon black is fed into a reaction vessel, and 2a of nitric acid and 1.8a of maleic anhydride are added. The mixture is stirred at 50 rpm, and nitrogen is introduced as a protective gas. 1.5a of cerium ammonia nitrate is added, and the temperature is raised to 70°C to initiate the polymer reaction. The reaction is allowed to proceed for at least 2 hours until the internal temperature stabilizes, completing the grafting modification of the conductive carbon black. The modified conductive carbon black corresponding to the initial 10a is then divided into two batches in a 7:3 ratio. The modified conductive carbon black exhibits a uniform particle size distribution, ensuring that the final product possesses superior electrical and mechanical properties, such as better volume resistivity, tensile strength, and elongation at break. This effectively mitigates the risk of high-voltage breakdown, and this step is a prerequisite for reducing branched chains. Consequently, the number of protrusions on the surface of the modified conductive carbon black is also significantly reduced. Batch A, comprising 70% of the total, and batch B, comprising 30%, are designated as Batch B. Batch A's conductive carbon black is mixed with EVA resin, while batch B's is mixed with polyimide. The materials from both batches are fed into separate flat vulcanizing machines. In addition to the original EVA resin, batch A's conductive carbon black requires the addition of 0.7a of polyacrylic acid or polycarboxylate as a dispersant and 0.3a of silane coupling agent, evenly spread on an 80×80×1mm sheet. 3 In the mold cavity, it is hot-pressed at 160℃ and 10MPa for 15 minutes. In addition to the original polyimide, the conductive carbon black in batch B also requires the addition of 0.5a of perfluoropolyether oil or silica mineral oil as a lubricant and 0.5a of 2,6-di-tert-butyl-4-methylphenol or 4,4'-thiobis(6-tert-butyl-3-methylphenol) as an antioxidant, which is also evenly spread on an 80×80×1mm surface. 3 In the mold cavity, the material was hot-pressed at 160℃ and 10MPa for 10 minutes. After vulcanization, batches A and B of the material were held under pressure and cooled to room temperature before being removed. The material treated in this way did not exhibit significant phase separation; the interparticle distance was appropriate, and there was a tendency for them to gradually aggregate, demonstrating high clustering properties. This highly interconnected structure can provide greater charge transport and optimize the electrical properties of the shielding material. The folded crystallinity of the treated chain segments was significantly reduced, inhibiting the formation of large crystals. This further reduces the number of protrusions to ensure surface smoothness and also disrupts internal integrity, facilitating the strengthening of anisotropy and mutual attraction between different batches of essentially the same material.

[0019] After vulcanization and cooling, batches A and B of materials were first kept at 80°C for 3 minutes to eliminate thermal history. Then, they were added to an internal mixer along with 0.2a vinylpyrrolidone, 0.3a N.N'-ethylene bis-stearamide, 0.2a polyethyleneimine, and 1.3a sodium polyacrylate and mixed at 110°C for 10 minutes.

[0020] Immediately immerse or atomize the mixed material with a peroxide, such as dicumyl peroxide or di-tert-butyldicumyl peroxide, before rapidly feeding it into the extruder to avoid over-oxidation. For immersion, the wetting time should be controlled within 12 seconds; for atomization, the atomization temperature should be maintained at 65℃, and the atomization time should not exceed 45 seconds. The effects of these two methods are similar, and the choice mainly depends on the process preference. If output is prioritized, immersion is chosen; if quality is prioritized, atomization is chosen. There is no option to combine both, as even a compromise would involve two processes, doubling the time spent on preparation and completion. Regardless of the method chosen, the minimum time limit for this step depends on the degree of peroxide adsorption by the material. Set the extruder to four temperature zones: 120, 135, 140, and 150℃, with an extrusion speed of 110 r / min. The extruded material is dried after being cooled with water and then fed back into the vulcanizing machine. The vulcanizing machine is kept at a temperature of 180℃ and a pressure of 10MPa. After hot pressing for 15 minutes, an ultra-smooth semiconductor shielding layer with improved interfacial bonding strength is obtained. Example

[0021] A method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer involves first grafting conductive carbon black onto its surface using an acid ester, preferably maleic anhydride. Specifically, the conductive carbon black is washed with a solvent prepared with baking soda. The amount of baking soda is not critical; its purpose is to remove unnecessary impurities and activate the functional groups within the conductive carbon black. The sulfur content of the conductive carbon black must be less than 0.02%, and the residue on a 325-mesh sieve must be less than 2 ppm. Using 10a as the mass fraction of the conductive carbon black, the washed conductive carbon black is fed into a reaction vessel, and 2a of nitric acid and 1.8a of maleic anhydride are added. The mixture is stirred at 50 rpm, and nitrogen is introduced as a protective gas. 1.5a of cerium ammonia nitrate is added, and the temperature is raised to 70°C to initiate the polymer reaction. The reaction is allowed to proceed for at least 2 hours until the internal temperature stabilizes, completing the grafting modification of the conductive carbon black. The modified conductive carbon black corresponding to the initial 10a is then divided into two batches in a 7:3 ratio.

[0022] Batch A, comprising 70% of the total, and batch B, comprising 30%, are designated as Batch B. Batch A's conductive carbon black is mixed with EVA resin, while batch B's is mixed with polyimide. The materials from both batches are fed into separate flat vulcanizing machines. In addition to the original EVA resin, batch A's conductive carbon black requires the addition of 0.7a of polyacrylic acid or polycarboxylate as a dispersant and 0.3a of silane coupling agent, evenly spread on an 80×80×1mm sheet. 3In the mold cavity, it is hot-pressed at 160℃ and 10MPa for 15 minutes. In addition to the original polyimide, the conductive carbon black in batch B also requires the addition of 0.5a of perfluoropolyether oil or silica mineral oil as a lubricant and 0.5a of 2,6-di-tert-butyl-4-methylphenol or 4,4'-thiobis(6-tert-butyl-3-methylphenol) as an antioxidant, which is also evenly spread on an 80×80×1mm surface. 3 The materials were hot-pressed in the mold cavity at 160℃ and 10MPa for 10 minutes. After vulcanization, batches A and B of the materials were held under pressure and cooled to room temperature before being removed.

[0023] After vulcanization and cooling, batches A and B of materials were first kept at 80°C for 3 minutes to eliminate thermal history. Then, they were added to an internal mixer along with 0.2a vinylpyrrolidone, 0.3a N.N'-ethylene bis-stearamide, 0.2a polyethyleneimine, and 1.3a sodium polyacrylate and mixed at 90°C for 8 minutes.

[0024] The mixed material is immediately soaked or atomized with a peroxide, such as dicumyl peroxide or di-tert-butyldicumyl peroxide, and then quickly fed into the extruder to avoid over-oxidation. For soaking, the soaking time should be controlled within 12 seconds; for atomization, the atomization temperature should be maintained at 65℃, and the atomization time should not exceed 45 seconds. The minimum time limit depends on the degree of peroxide adsorption by the material. The extruder is set to four temperature zones: 120, 135, 140, and 150℃, with an extrusion speed of 100 r / min. The extruded material is water-cooled and dried, then re-fed into the vulcanizing machine. The vulcanizing machine is maintained at a temperature of 180℃ and a pressure of 10 MPa for 15 minutes to obtain an ultra-smooth semiconductor shielding layer with improved interfacial bonding strength. Example

[0025] A method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer involves first grafting conductive carbon black onto its surface using an acid ester, preferably maleic anhydride. Specifically, the conductive carbon black is washed with a solvent prepared with baking soda. The amount of baking soda is not critical; its purpose is to remove unnecessary impurities and activate the functional groups within the conductive carbon black. The sulfur content of the conductive carbon black must be less than 0.02%, and the residue on a 325-mesh sieve must be less than 2 ppm. Using 10a as the mass fraction of the conductive carbon black, the washed conductive carbon black is fed into a reaction vessel, and 2a of nitric acid and 1.8a of maleic anhydride are added. The mixture is stirred at 50 rpm, and nitrogen is introduced as a protective gas. 1.5a of cerium ammonia nitrate is added, and the temperature is raised to 70°C to initiate the polymer reaction. The reaction is allowed to proceed for at least 2 hours until the internal temperature stabilizes, completing the grafting modification of the conductive carbon black. The modified conductive carbon black corresponding to the initial 10a is then divided into two batches in a 7:3 ratio.

[0026] Batch A, comprising 70% of the total, and batch B, comprising 30%, are designated as Batch B. Batch A's conductive carbon black is mixed with EVA resin, while batch B's is mixed with polyimide. The materials from both batches are fed into separate flat vulcanizing machines. In addition to the original EVA resin, batch A's conductive carbon black requires the addition of 0.7a of polyacrylic acid or polycarboxylate as a dispersant and 0.3a of silane coupling agent, evenly spread on an 80×80×1mm sheet. 3 In the mold cavity, it is hot-pressed at 160℃ and 10MPa for 15 minutes. In addition to the original polyimide, the conductive carbon black in batch B also requires the addition of 0.5a of perfluoropolyether oil or silica mineral oil as a lubricant and 0.5a of 2,6-di-tert-butyl-4-methylphenol or 4,4'-thiobis(6-tert-butyl-3-methylphenol) as an antioxidant, which is also evenly spread on an 80×80×1mm surface. 3 The materials were hot-pressed in the mold cavity at 160℃ and 10MPa for 10 minutes. After vulcanization, batches A and B of the materials were held under pressure and cooled to room temperature before being removed.

[0027] After vulcanization and cooling, batches A and B of materials were first kept at 80°C for 3 minutes to eliminate thermal history. Then, they were added to an internal mixer along with 0.2a vinylpyrrolidone, 0.3a N.N'-ethylene bis-stearamide, 0.2a polyethyleneimine, and 1.3a sodium polyacrylate and mixed at 120°C for 15 minutes.

[0028] The mixed material is immediately soaked or atomized with a peroxide, such as dicumyl peroxide or di-tert-butyldicumyl peroxide, and then quickly fed into the extruder to avoid over-oxidation. For soaking, the soaking time should be controlled within 12 seconds; for atomization, the atomization temperature should be maintained at 65℃, and the atomization time should not exceed 45 seconds. The minimum time limit depends on the degree of peroxide adsorption by the material. The extruder is set to four temperature zones: 120, 135, 140, and 150℃, with an extrusion speed of 120 r / min. The extruded material is water-cooled and dried, then re-fed into the vulcanizing machine. The vulcanizing machine is maintained at a temperature of 180℃ and a pressure of 10 MPa. After hot pressing for 15 minutes, an ultra-smooth semiconductor shielding layer with improved interfacial bonding strength is obtained.

[0029] The interface strength of Examples 1-3 did not differ significantly, with only reasonable differences in other aspects such as charge transport rate, characterization, thermodynamic properties, and mechanical properties. The overall interface bonding strength was improved by at least 70% compared to the previous generation of products.

[0030] It should be noted that this specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer, characterized in that: The conductive carbon black was grafted onto the surface using an acid ester and then divided into two parts. Two portions of modified conductive carbon black were mixed evenly with EVA resin and polyimide, respectively, and then sent to a flat vulcanizing machine for vulcanization. The vulcanized material, along with vinylpyrrolidone, NN'-ethylene bis-stearamide, polyethyleneimine, and sodium polyacrylate, is added to a mixer and mixed. The mixed material is immediately wetted with peroxide and then quickly fed into an extruder. After extrusion, it is vulcanized again to obtain an ultra-smooth semiconductor shielding layer with improved interfacial bonding strength.

2. The method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer according to claim 1, characterized in that: The ester used for modifying conductive carbon black is maleic anhydride. After washing the conductive carbon black with alkali, nitric acid and maleic anhydride are added. Cerium nitrate is added under nitrogen protection and the mixture is heated to react. After the reaction is completed, the carbon black is washed with water and filtered to obtain the surface-grafted ester modified conductive carbon black.

3. The method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer according to claim 1, characterized in that: The modified conductive carbon black was divided into two parts in a 7:3 ratio. 70% of the modified conductive carbon black was mixed with EVA resin, and 30% of the modified conductive carbon black was mixed with polyimide.

4. The method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer according to claim 3, characterized in that: The stirred modified conductive carbon black and EVA resin were added to the dispersant and silane coupling agent, and evenly spread in the mold cavity. The mixture was then hot-pressed at 160℃ and 10MPa pressure for 15 minutes. The stirred modified conductive carbon black and polyimide were added to the lubricant and antioxidant, and spread evenly in the cavity. The mixture was then hot-pressed at 160℃ and 10MPa for 10 minutes. After vulcanization, the two batches of material were kept under pressure and cooled to room temperature before being removed.

5. The method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer according to claim 4, characterized in that: The dispersant is polyacrylic acid or polycarboxylate; The lubricant is perfluoropolyether oil or silica mineral oil; The antioxidant is 2,6-di-tert-butyl-4-methylphenol or 4,4'-thiobis(6-tert-butyl-3-methylphenol).

6. The method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer according to claim 1, characterized in that: The mixing temperature in the internal mixer is 90~120℃, and the mixing time is 8~15min.

7. The method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer according to claim 1, characterized in that: The selected peroxide is dicumyl peroxide or di-tert-butyl peroxide. The soaking time should be controlled within 12 seconds.

8. The method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer according to claim 7, characterized in that: The extruder is set with four temperature zones of 120, 135, 140 and 150°C, and the extrusion speed is 100~120 r / min.

9. The method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer according to claim 8, characterized in that: The extruded material is dried after being cooled with water and then sent back to the vulcanizing machine for vulcanization. It is then hot-pressed at 180℃ and 10MPa for 15 minutes.

10. The method for improving the interfacial bonding strength of an ultra-smooth semiconductor shielding layer according to claim 1, characterized in that: The treatment of well-mixed materials before they are fed into the extruder is achieved by replacing the wetting method with atomization contact. The atomization temperature is maintained at 65℃ and the atomization time does not exceed 45s.

Images