Composite conductive material and molded body

Abstract

The application provides a composite conductive material and a molded body, and a first aspect provides a composite conductive material used for generating an article through a high-temperature sintering process, comprising, based on the total weight of the composite conductive material: 12-35 wt% graphite, 20-40 wt% SiC wear-resistant phase, and 25-45 wt% low-alkali borosilicate glass powder; wherein, in the low-alkali borosilicate glass powder, Na2O+K2O<0.1 wt%. Through compounding a graphite-glass composite system, the weight ratio of 12-35 wt% graphite is conducive to forming an electrically conductive network in the high-temperature sintering process; the 20-40 wt% SiC wear-resistant phase is conducive to forming a high-proportion SiC hard skeleton, enhancing the wear resistance of the article, and the glass powder as a binder phase is additionally conducive to reducing the cost; and the low-alkali glass phase is conducive to eliminating the hidden dangers of resistance drift and dendrite short circuit.

Description

Technical Field

[0001] This invention relates to the field of toner cartridge technology, and in particular to a composite conductive material and a molded body. Background Technology

[0002] Composite rollers such as charging rollers, developing rollers, toner delivery rollers, and transfer rollers are crucial components in office equipment like electrostatic copiers and printers. Their primary function is to provide electrical charge to the photosensitive drum. The performance of these rollers directly impacts print quality and the lifespan of the equipment. Currently, common charging rollers, developing rollers, toner delivery rollers, and transfer rollers on the market mainly consist of a roller core and a conductive layer. The roller core, as the core component of these rollers, has a decisive influence on their overall performance due to its material, structure, and performance. Furthermore, the substrates of magnetic rollers, drum cores, and printer heating rollers also have similar electrical and mechanical performance requirements as the roller core.

[0003] The existing technology uses a composite structure with a non-metallic core wrapped with a conductive metal layer. Due to the mismatch of the inherent properties of the materials and the complexity of the manufacturing process, there are technical problems such as unreliable interface bonding, difficulty in controlling dimensional accuracy, poor resistance uniformity, and high manufacturing cost.

[0004] Therefore, there is an urgent need to develop a roller core with good material system compatibility and simplified manufacturing process. The comprehensive balance of the roller core's conductivity, mechanical strength, wear resistance and manufacturing cost is a problem that needs to be solved in the current roller core technology. Summary of the Invention

[0005] To address the issues of good material system compatibility, simplified manufacturing process, and balanced conductivity, mechanical strength, wear resistance, and manufacturing cost of the shaft core, this invention provides a composite conductive material and a molded body.

[0006] The first aspect of the present invention provides a composite conductive material for producing articles by a high-temperature sintering process, comprising, by weight of the composite conductive material: 12-35 wt% graphite, 20-40 wt% SiC wear-resistant phase, and 25-45 wt% low-alkali borosilicate glass powder; In the low-alkali borosilicate glass powder, Na2O+K2O<0.1 wt%.

[0007] Preferably, the wear-resistant SiC phase comprises α-SiC micro powder and β-SiC whiskers, wherein, based on the total weight of the composite conductive material, the α-SiC micro powder accounts for 15–25 wt% and the β-SiC whiskers account for 5–15 wt%.

[0008] Preferably, the α-SiC micro powder is composed of fine powder with a D50 of 1–3 μm and coarse powder with a D50 of 5–9 μm; more preferably, the α-SiC micro powder is composed of fine powder with a D50 of 1–3 μm and coarse powder with a D50 of 5–8 μm, and the mass ratio of fine powder to coarse powder is 60%-80%:20%-40%; the β-SiC whiskers have a diameter of 0.5-10 μm and an aspect ratio of 10-30; more preferably, the β-SiC whiskers have a diameter of 0.5-5 μm; and even more preferably, the β-SiC whiskers have a diameter of 0.5-51 μm.

[0009] Preferably, the graphite is artificial graphite with a particle size D50 of 3–10 μm.

[0010] Preferably, the composite conductive material further includes 0.5–5 wt% nano-carbon black or carbon nanotubes; more preferably, the composite conductive material further includes 0.5–2 wt% nano-carbon black or carbon nanotubes.

[0011] Preferably, the composite conductive material further includes <3%wt of an interface wetting agent, wherein the interface wetting agent is TiO2 micro powder (D50≤1μm) or metallic Si micro powder. The low-alkali borosilicate glass powder is an alkali-free aluminoborosilicate glass powder. The alkali-free aluminoborosilicate glass powder, by weight, contains 42–48% SiO2, 16–20% B2O3, 8–12% Al2O3, 6–9% CaO, 3–5% MgO, 1–3% TiO2 and 2–4% ZnO.

[0012] Preferably, the composite conductive material further includes a PTC self-limiting phase, and by weight of the composite conductive material, the composite conductive material includes 12-30 wt% graphite, 20-38 wt% SiC wear-resistant phase, 5-15 wt% PTC self-limiting phase, and 25-40 wt% low-alkali borosilicate glass powder.

[0013] A second aspect of the present invention provides a molded body for a toner cartridge, which is formed by a high-temperature sintering process from the composite conductive material according to claims 1-7.

[0014] A third aspect of the present invention provides a molded body for a toner cartridge, comprising a ceramic core and a coating, wherein the coating is disposed on the surface of the core and the coating is formed by modifying the composite conductive material according to claims 1-7.

[0015] Preferably, a mullite (3Al2O3·2SiO2) interface transition layer is formed between the inner core and the coating.

[0016] The beneficial effects of this invention are as follows: by compounding the graphite-glass composite system, a graphite weight ratio of 12-35 wt% is beneficial to the formation of a conductive network in the high-temperature sintering process; a wear-resistant SiC phase of 20-40 wt% is beneficial to the formation of a high proportion of SiC hard skeleton, which enhances the wear resistance of the product; glass powder as a binder phase is also beneficial to reducing costs; and a low-alkali glass phase is beneficial to eliminating the hidden dangers of resistance drift and dendrite short circuits. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a cross-sectional view of the molded body along the axial direction in one embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the processing flow of the molded body in one embodiment of the present invention.

[0019] Figure label: Core 10 Coating 20 Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The first aspect of the present invention provides a composite conductive material for producing articles by a high-temperature sintering process, comprising, by weight of the composite conductive material: 12-35 wt% graphite, 20-40 wt% SiC wear-resistant phase, and 25-45 wt% low-alkali borosilicate glass powder; In the low-alkali borosilicate glass powder, Na2O+K2O<0.1 wt%.

[0022] By using a graphite-glass composite system with a graphite weight ratio of 12-35 wt%, it is beneficial to form a conductive network during the high-temperature sintering process, resulting in a product with a resistivity between 10⁻⁶ and 10⁻⁶. 2 -10 9 Ω·cm, more preferably, the resistivity of the resulting article is between 10 Ω·cm. 2 -10 6 Ω·cm; most preferably, the resistivity of the resulting product is between 10 Ω·cm. 2 -10 5Ω·cm; 20-40 wt% SiC wear-resistant phase is conducive to forming a high proportion of SiC hard skeleton, which enhances the wear resistance of the product. Glass powder as a binder phase is also conducive to reducing costs. Low alkali glass phase is conducive to eliminating the hidden dangers of resistance drift and dendrite short circuit.

[0023] More preferably, the composite conductive material comprises 15-30 wt% graphite based on the total weight of the composite conductive material, and most preferably, the composite conductive material comprises 18-25 wt% graphite.

[0024] In some embodiments, the wear-resistant SiC phase comprises α-SiC micro powder and β-SiC whiskers, wherein, based on the total weight of the composite conductive material, the α-SiC micro powder accounts for 15–25 wt% and the β-SiC whiskers account for 5–15 wt%.

[0025] In some embodiments, the α-SiC micro powder is composed of fine powder with a D50 of 1–3 μm and coarse powder with a D50 of 5–9 μm. In more preferred embodiments, the α-SiC micro powder is composed of fine powder with a D50 of 1–3 μm and coarse powder with a D50 of 5–8 μm, and the mass ratio of fine powder to coarse powder is 60%–80%: 20%–40%. The diameter of the β-SiC whiskers is 0.5–10 μm. In more preferred embodiments, the diameter of the β-SiC whiskers is 0.5–5 μm. In even more preferred embodiments, the diameter of the β-SiC whiskers is 0.5–51 μm, and the aspect ratio is 10–30.

[0026] In some embodiments, the graphite is artificial graphite with a particle size D50 of 3–10 μm.

[0027] In some embodiments, the composite conductive material further includes 0.5–5 wt% nano-carbon black or carbon nanotubes, and in more preferred embodiments, the composite conductive material further includes 0.5–2 wt% nano-carbon black or carbon nanotubes.

[0028] In some embodiments, the composite conductive material further includes <3%wt of an interface wetting agent, wherein the interface wetting agent is TiO2 micro powder (D50≤1μm) or metallic Si micro powder. Low-alkali borosilicate glass powder is alkali-free aluminoborosilicate glass powder; In some embodiments, the alkali-free aluminoborosilicate glass powder contains, by weight, 42–48% SiO2, 16–20% B2O3, 8–12% Al2O3, 6–9% CaO, 3–5% MgO, 1–3% TiO2, and 2–4% ZnO. In some other embodiments, the alkali-free aluminoborosilicate glass powder, by weight, comprises 42–48% SiO2, 16–20% B2O3, 8–12% Al2O3, 6–9% CaO, 3–5% MgO, 1–3% TiO2, 1–10% ZrO2 and 2–4% ZnO.

[0029] Graphite has extremely low surface energy (approximately 40–50 mJ / m²) and poor wettability with oxide glass melts (surface energy 200–300 mJ / m²), with contact angles typically >120°. This results in the glass melt failing to spread effectively on the graphite surface, leading to continuous pores around the graphite particles after sintering and low coating density. Introducing TiO2 micropowder, preferably with a D50 ≤ 1 μm and an addition amount of 0.5–2 wt%, allows TiO2 to partially reduce to TiC or TiOx at high temperatures, forming chemical bonds with graphite and resulting in good wetting of its outer layer with the glass melt. Adding B2O3 (15–20 wt%) and a small amount of TiO2 (1–3 wt%) to alkali-free aluminoborosilicate glass powder can reduce the surface tension of the glass. B2O3, as a network former, has a [BO3] triangular structure that can break the silicon-oxygen network connections, reducing melt viscosity and surface tension; TiO2 can form Ti–C bonds with graphite surface defect sites at high temperatures, while also being compatible with glass melt. The glass content in the composite conductive material is set at 25–45 wt%, and the sufficient glass phase can fill the pores between graphite and SiC particles, achieving high density through volume filling even with incomplete wetting.

[0030] In some embodiments, the composite conductive material further includes a PTC self-limiting phase, and by weight of the composite conductive material, the composite conductive material includes 12-30 wt% graphite, 20-38 wt% SiC wear-resistant phase, 5-15 wt% PTC self-limiting phase, and 25-40 wt% low-alkali borosilicate glass powder.

[0031] A second aspect of the present invention provides a molded body for a toner cartridge, formed by a high-temperature sintering process using a composite conductive material according to the first aspect. The molded body is an integral piece made of the same material, for example, a solid shaft used as the core of a charging roller, developing roller, toner feeding roller, or transfer roller; or for example, a hollow tubular integral structure used as a substrate for a magnetic roller, drum core, or printer heating roller.

[0032] A molded body for a toner cartridge includes a ceramic core and a coating. The coating is disposed on the surface of the core and is prepared from a composite conductive material according to a first aspect. The ceramic core and the coating are formed by a high-temperature sintering process. An example is a solid shaft-like structure, used as a roller core for charging rollers, developing rollers, toner feeding rollers, and transfer rollers; another example is a hollow tubular structure, with coatings on both the inner and outer surfaces of the hollow tube, used as a substrate for magnetic rollers, drum cores, and printer heating rollers.

[0033] In some embodiments, a mullite (3Al2O3·2SiO2) interface transition layer is formed between the core and the coating.

[0034] The technical solution of the present invention will be described below with reference to specific embodiments: Example

[0035] like Figure 1 A molded body for a toner cartridge includes a ceramic inner core 10 and a coating 20, wherein the coating 20 is disposed on the surface of the inner core 10; Figure 2 Example Figure 1 A schematic diagram of the processing flow of the molded body.

[0036]

[0037] S2, Substrate Pretreatment Ceramic core material: 75%–99% Al2O3 ceramic, roughened by sandblasting, ultrasonic cleaning or mold forming, and then preheated.

[0038] S3, Coating and Molding.

[0039] S4. Drying.

[0040] S5, Nitrogen-protected sintering: Peak temperature: 850-900℃.

[0041] S6. Post-treatment: centerless fine grinding and ultrasonic cleaning.

[0042] After the process is completed and the finished product is obtained, the surface resistivity uniformity is tested: the resistivity at all measuring points is within 1×10⁻⁶. 2 –1×10 4 Within the range of Ω·cm. Furthermore, the fracture toughness of the coating was measured to be between 1.5 and 2.0 MPa·m¹ / ².

[0043] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite conductive material, characterized in that, Used to produce products by high-temperature sintering process, the composite conductive material comprises, by total weight: 12-35 wt% graphite, 20-40 wt% SiC wear-resistant phase, and 25-45 wt% low-alkali borosilicate glass powder; In the low-alkali borosilicate glass powder, Na2O+K2O<0.1 wt%.

2. The composite conductive material as described in claim 1, characterized in that, The wear-resistant SiC phase comprises α-SiC micro powder and β-SiC whiskers, wherein, based on the total weight of the composite conductive material, the mass percentage of α-SiC micro powder is 15–25 wt%, and the mass percentage of β-SiC whiskers is 5–15 wt%.

3. The composite conductive material as described in claim 2, characterized in that, The α-SiC micro powder is composed of fine powder with D50=1–3μm and coarse powder with D50=5–9μm, with a mass ratio of fine powder to coarse powder of 60%-80%:20%-40%; the β-SiC whiskers have a diameter of 0.5-10μm and an aspect ratio of 10-30.

4. The composite conductive material as described in claim 1, characterized in that, The graphite is artificial graphite with a particle size D50 of 3–20 μm.

5. The composite conductive material as described in claim 1, characterized in that, The composite conductive material also includes 0.5–5 wt% nano-carbon black or carbon nanotubes.

6. The composite conductive material as described in claim 1, characterized in that, The composite conductive material also includes <3%wt of an interface wetting agent, which is TiO2 micro powder (D50≤1μm) or metallic Si micro powder. The low-alkali borosilicate glass powder is an alkali-free aluminoborosilicate glass powder. The alkali-free aluminoborosilicate glass powder, by weight, contains 42–48% SiO2, 16–20% B2O3, 8–12% Al2O3, 6–9% CaO, 3–5% MgO, 1–3% TiO2 and 2–4% ZnO.

7. The composite conductive material as described in claim 1, characterized in that, The composite conductive material further includes a PTC self-limiting phase. Based on the total weight of the composite conductive material, the composite conductive material includes 12-30 wt% graphite, 20-38 wt% SiC wear-resistant phase, 5-15 wt% PTC self-limiting phase, and 25-40 wt% low-alkali borosilicate glass powder.

8. A molded body for a toner cartridge, characterized in that, The composite conductive material according to claims 1-7 is formed by a high-temperature sintering process.

9. A molded body for a toner cartridge, characterized in that, It includes a ceramic core and a coating, wherein the coating is disposed on the surface of the core and the coating is prepared by means of the composite conductive material according to claims 1-7.

10. The molded body as claimed in claim 9, wherein a mullite (3Al2O3·2SiO2) interface transition layer is formed between the inner core and the coating.

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