Flame-retardant high-voltage-resistant insulating rubber material for connector and preparation method thereof

Abstract

The invention provides a flame-retardant and high-pressure-resistant insulating rubber material for a connector and a preparation method thereof, and relates to the technical field of rubber materials, the flame-retardant and high-pressure-resistant insulating rubber material is prepared by mixing and vulcanizing raw materials comprising the following components: raw rubber, an active agent, an antioxidant, an anti-scorching acid acceptor, a surfactant, a processing aid, a flame retardant, a reinforcing agent, a vulcanizing agent and a vulcanization accelerator; the method comprises the following steps: S2, plastifying: plastifying raw rubber on an open mill until the raw rubber is softened and the surface is smooth, and then covering a roller; s3, preliminary mixing: adding an active agent, an antioxidant, an anti-scorching acid-absorbing agent and a processing aid, and uniformly mixing; s4, final mixing and batch-off: adding the surfactant, the flame retardant, the color master batch and the reinforcing agent, and uniformly mixing; according to the invention, the comprehensive performance of high elasticity, V-0-level flame retardance, high insulation, aging resistance, antistatic property and good sealing performance is essentially realized through the formula design material; and the theoretical performance is ensured to be stable and reliably reflected in a final product through an optimized preparation process.

Description

Technical Field

[0001] This invention relates to the field of rubber materials technology, and in particular to a flame-retardant, high-voltage resistant insulating rubber material for connectors and its preparation method. Background Technology

[0002] Currently, the insulating components of domestic electronic connectors are mainly made of plastics (such as PA, PBT, etc.). These materials have many drawbacks: poor elasticity, making them prone to brittleness under insertion, removal, and vibration conditions; poor low-temperature resistance, easily hardening and failing at low temperatures; as insulators, they easily generate static electricity due to friction, attracting dust and dirt, affecting contact reliability; poor aging resistance, prone to cracking and powdering after long-term use; and susceptible to stress fatigue and damage under continuous stress. In addition, their sealing performance is also poor, making it difficult to meet the requirements of high protection levels. Therefore, designing a connector material that combines good elasticity, excellent flame-retardant insulation properties, environmental aging resistance, and reliable sealing is of great practical significance. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a flame-retardant and high-voltage resistant insulating rubber material for connectors and its preparation method; This material uses neoprene rubber as a base and, through a specific formulation system and process, it simultaneously possesses high elasticity, excellent flame retardant properties (reaching UL94 V-0 rating), high volume resistivity, and the ability to withstand high voltage. It is also resistant to aging, fatigue, and has good sealing properties, making it particularly suitable for electrical connectors with high safety and reliability requirements.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A flame-retardant and high-voltage resistant insulating rubber material for connectors is obtained by mixing and vulcanizing raw materials containing the following components: raw rubber, activator, antioxidant, scorch inhibitor and acid absorber, surfactant, processing aid, flame retardant, reinforcing agent, color masterbatch, vulcanizing agent and vulcanization accelerator. Based on the total weight of the raw materials, the weight percentage of each component is as follows: Raw rubber: 40%-44%; Surfactant: 0.3%-0.6%; Antioxidant: 0.6%-1.0%; Scorch inhibitor and acid absorber: 1.2%-2.0%; Surfactant: 0.2%-0.6%; Processing aids: 1.8%-2.6%; Flame retardant: 10%-14%; Reinforcing agent: 32%-36%; Masterbatch: 2.5%-3.5%; Vulcanizing agent: 2.2%-3.0%; Vulcanization accelerator: 0.8%-1.2%.

[0005] Furthermore, the raw rubber is chloroprene rubber.

[0006] Furthermore, the activator is stearic acid; the scorch absorbing agent is active magnesium oxide.

[0007] Furthermore, the surfactant is bis-(γ-triethoxysilylpropyl)tetrasulfide.

[0008] Furthermore, the flame retardant is melamine cyanurate.

[0009] Furthermore, the reinforcing agent is calcined kaolin.

[0010] Furthermore, the processing aid is low molecular weight polyethylene wax; the antioxidant is 4-octyldiphenylamine; the vulcanizing agent is zinc oxide; and the vulcanization accelerator is diethylthiourea.

[0011] A method for preparing a flame-retardant, high-voltage resistant insulating rubber material for connectors includes the following steps: S1. Weigh each raw material component according to the stated weight percentage; S2, Plasticizing: Place the raw rubber on a rolling mill and plasticize it until it softens and the surface is smooth, then wrap it around the rollers; S3. Preliminary mixing: Add activators, antioxidants, scorch inhibitors and acid absorbers, and processing aids, and mix well; S4. Final mixing and flaking: Add surfactants, flame retardants, color masterbatches and reinforcing agents, and mix well; Then add vulcanizing agent and vulcanization accelerator, mix well, and then pass through a thin sheet to obtain the compound rubber base material. S5. Vulcanization molding: The compounded rubber substrate is subjected to compression molding and vulcanization at a vulcanization temperature of 140-160℃, a vulcanization pressure of 70-90MPa, and a vulcanization time of 350-450 seconds to obtain the finished product.

[0012] Furthermore, in step S2, the gap between the mill rollers is adjusted to 1mm, and the raw rubber is softened by passing through the rollers 5-7 times. After wrapping the rollers, the left and right sides are alternately cut to plasticize until the surface is smooth. During plasticizing, the temperature of the mill rollers is controlled not to exceed 50℃. In step S4, after adding the vulcanizing agent and vulcanization accelerator and mixing them evenly, the triangular wrapping and thin-passing operations are performed, and the flat-winding operation is performed before the film is unwound to drive out air bubbles.

[0013] Furthermore, in step S4, the compounded rubber substrate after sheeting needs to be left to stand at 20-25℃ for 6-10 hours before proceeding to step S5 for vulcanization molding.

[0014] The flame-retardant, high-voltage resistant insulating rubber material for connectors and its preparation method provided by this invention, by using neoprene rubber as a matrix and designing a specific synergistic formulation system and key processes, specifically overcomes the inherent defects of the plastic materials described in the background art, and achieves the following significant effects: 1. Addressing issues of poor elasticity, brittleness, and insufficient fatigue resistance: The solution's corresponding effects: Using chloroprene rubber as the base raw rubber (accounting for 40%-44%), which itself has excellent elasticity and flexibility, this solution fundamentally replaces rigid plastics, enabling the final material to effectively buffer insertion and vibration stress through elastic deformation, avoiding brittle fracture and significantly improving mechanical fatigue resistance.

[0015] 2. For products that are not resistant to low temperatures, are prone to aging, and have poor sealing performance: Formula and its corresponding effects: The chloroprene rubber matrix provides a good foundation for low-temperature resistance. The addition of antioxidant 4-octyldiphenylamine and scorch scavenger and acid absorber activated magnesium oxide constitutes a highly efficient and stable system. This synergistically inhibits the aging and degradation of the material under thermal and oxygen conditions, ensuring the retention of elasticity and the stability of physical properties over long-term use. This solves the problems of low-temperature hardening and cracking / powdering after long-term use. Simultaneously, the inherent high elasticity and compressibility of rubber materials allow for a tighter fit that plastics cannot achieve, giving the product excellent sealing performance.

[0016] The method and its corresponding effects: After vulcanization, the compound is required to be left to stand at 20-25℃ for 6-10 hours, which helps stress relaxation and further uniform diffusion of compounding agents, reduces internal defects, and improves the dimensional stability and durability of the final product.

[0017] 3. For items that easily generate static electricity and attract dust: The solution's corresponding effects: Chloroprene rubber itself has a better antistatic tendency than plastics, and the addition of the surfactant bis-(γ-triethoxysilylpropyl)tetrasulfide to the formulation not only improves the dispersion of fillers, but may also affect surface properties to a certain extent, thus reducing the generation and accumulation of tribostatic static electricity and lowering the risk of poor contact caused by electrostatic adsorption of contaminants.

[0018] 4. For flame retardant and high voltage resistance requirements: Formula and its corresponding effects: By adding 10%-14% melamine cyanurate as a highly efficient flame retardant and selecting calcined kaolin (32%-36%) as a reinforcing agent, the two work synergistically to significantly improve the flame retardancy of the material while ensuring mechanical properties, achieving a UL94 V-0 rating. Kaolin, as a high-performance insulating mineral filler, greatly improves the volume resistivity and breakdown strength of the material when combined with neoprene rubber.

[0019] Method and corresponding effects: In the mixing process, key components such as flame retardants and reinforcing agents are fully mixed before being added to the vulcanization system (step S4). Through subsequent operations such as triangular wrapping, thin-passing, and flat-rolling, the uniform dispersion of these functional fillers in the matrix is ​​ensured, avoiding local insulation weaknesses caused by agglomeration. This is a key process guarantee for achieving stable and excellent insulation and flame retardant performance.

[0020] 5. Regarding processing reliability and final performance consistency: Method and corresponding effects: Strict control of roller temperature (≤50℃) and roller gap (1mm) during plasticizing effectively avoids early scorching of chloroprene rubber, allowing it to soften fully and laying the foundation for subsequent uniform mixing; The vulcanization stage adopts a molding process of 140-160℃ and 70-90MPa. The high temperature and high pressure ensure the fullness and uniformity of the crosslinking reaction, so that the performance of the formula design can be fully realized and the product has good density.

[0021] In summary, this invention not only achieves comprehensive performance in terms of high elasticity, flame retardancy (V-0 rating), high insulation, aging resistance, antistatic properties, and good sealing through formulation design (chloroprene rubber matrix, specific flame retardant / reinforcing / stabilizing system); Furthermore, through optimized manufacturing processes (segmented mixing, low-temperature plasticizing, uniform dispersion operation, and precise vulcanization), these theoretical properties are ensured to be stably and reliably reflected in the final product, fully meeting the stringent requirements of high-safety and high-reliability electrical connectors. Detailed Implementation

[0022] The flame-retardant, high-voltage resistant insulating rubber material for connectors and its preparation method described in the present invention will be described in detail below with reference to specific embodiments. The embodiments of the present invention are for illustrative purposes only and are not intended to limit the invention. Any modifications made under the premise of the inventive concept fall within the protection scope of the present invention. Example

[0023] This embodiment provides a flame-retardant, high-insulation-resistance, and high-voltage-resistant chloroprene rubber connector colored material and its preparation method.

[0024] 1. Raw material composition Based on the total weight of the raw materials, the composition of each group of the rubber material in this embodiment is shown in the table below:

[0025] The functions of each preferred raw material are briefly described below: Thiol-modified chloroprene rubber: As a raw rubber matrix, it achieves better storage stability by adjusting the molecular weight with thiol, and has a moderate crystallization rate, as well as excellent weather resistance, flame resistance, heat resistance, fatigue resistance and ozone aging resistance.

[0026] Stearic acid: As an activator, it improves the activity and cross-linking degree of the vulcanization system, improves dispersibility and flowability, and prevents sticking to the rollers.

[0027] 4-Octylated diphenylamine: As an antioxidant, it has low pollution and strong protective effects against thermo-oxidative aging and ozone aging.

[0028] Highly active magnesium oxide: As an anti-scorching and acid-absorbing agent, it promotes sulfidation, increases cross-linking density, neutralizes acidic substances, enhances flame retardancy, prevents scorching during processing, and improves processing safety and storage stability.

[0029] Bis-(γ-triethoxysilylpropyl)tetrasulfide: As a silane coupling agent surfactant, it promotes the bonding of reinforcing agents, flame retardants and rubber molecular chains, thereby improving physical and mechanical properties.

[0030] Low molecular weight polyethylene wax: as a processing aid, it improves processability and product release properties.

[0031] Melamine cyanurate: As a halogen-free and environmentally friendly flame retardant, it has high flame retardant efficiency and minimal impact on electrical, mechanical, and coloring properties.

[0032] Calcined kaolin: As a reinforcing agent, it significantly improves the electrical insulation and breakdown voltage of rubber, while also enhancing its physical and mechanical properties.

[0033] Zinc oxide: As a vulcanizing agent, it crosslinks rubber molecular chains to form a network structure, and also plays a reinforcing role, improving the strength, elasticity and wear resistance of the product.

[0034] Diethylthiourea: As a vulcanization accelerator, it accelerates the vulcanization reaction and improves crosslinking density and physical and mechanical properties.

[0035] The preparation method of this embodiment includes the following steps: S1. Preparation: Weigh each raw material component according to the above proportions.

[0036] S2. Raw Rubber Plasticizing: Adjust the roller gap of the open mill to 1mm, pass the raw rubber (thiol-modified chloroprene rubber) through the rollers six times to fully soften it, and then coat it onto the front roller; during the plasticizing process, use alternating cutters from left and right until the surface of the rubber compound becomes smooth and flat. Cooling water needs to be turned on during this process to control the roller temperature to not exceed 50℃.

[0037] S3. Adding additives: Add the activator (stearic acid), antioxidant (4-octyldiphenylamine), anti-scorching and acid-absorbing agent (high-activity magnesium oxide) and processing aid (low molecular weight polyethylene wax) to the roll compound in sequence; after all the additives have been "absorbed" by the rubber compound, cut the roll compound three times alternately from left to right to promote initial mixing.

[0038] S4. Mixing and Sheeting: Add the surfactant (bis-(γ-triethoxysilylpropyl)tetrasulfide), flame retardant (melamine cyanurate), color masterbatch (turquoise), and reinforcing agent (calcined kaolin) to the rubber compound in sequence. After it is fully incorporated, cut the rubber compound three times alternately from left to right. Then add the vulcanizing agent (zinc oxide) and vulcanization accelerator (diethylthiourea). After they are fully incorporated, cut the rubber compound three times again alternately from left to right, and make three triangular wraps. Then, the roller gap is adjusted to 0.5mm, and six triangular wraps are made. This operation aims to achieve a highly uniform dispersion of all additives in the rubber compound through high shear. Finally, adjust the roller gap to 3mm and roll it flat five times to remove any air bubbles that may be present inside the rubber compound. Sheet the well-mixed rubber compound and transfer it to a cold storage chamber set at 23℃ for 8 hours to cure, obtaining the mixed rubber base material.

[0039] S5. Vulcanization Molding: Take an appropriate amount of rubber material from the substrate after it has been left to stand, and place it in a preheated mold; under vulcanization conditions of 150℃ and 80MPa, mold and vulcanize for 400 seconds. After vulcanization is completed, demold to obtain the final rubber connector product.

[0040] Product performance testing The performance of the rubber product prepared according to the method of this embodiment was tested, and the results are as follows: Flame retardant performance: The material was tested in a vertical burning test chamber according to relevant standards and its flame retardant rating reached UL94-V0.

[0041] Insulation resistance: The surface resistance of the product is tested using a high resistance meter, and the resistance value can reach the order of 10^12 ohms, indicating excellent insulation performance.

[0042] Withstand voltage performance: The sample was tested with a voltage breakdown tester and held at 1500V for 1 minute without being broken down.

[0043] Low temperature resistance: Tested with a brittle temperature tester, the product did not crack after being placed in a -55℃ low temperature environment for 3 minutes.

[0044] Conclusion: The rubber material prepared in this embodiment, through specific component design and optimized preparation process, successfully achieved excellent comprehensive properties such as flame retardancy (94-V0 grade), high insulation resistance (10^12Ω), high voltage resistance (≥1500V / 1min), and low temperature resistance (-55℃). At the same time, the material also maintains the inherent high elasticity, excellent aging resistance, and fatigue resistance of neoprene rubber, fully meeting the requirements for high-performance connector insulation materials.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A flame-retardant, high-voltage resistant insulating rubber material for connectors, characterized in that, It is produced by mixing and vulcanizing raw materials containing the following components: raw rubber, activator, antioxidant, scorch inhibitor and acid absorber, surfactant, processing aid, flame retardant, reinforcing agent, color masterbatch, vulcanizing agent and vulcanization accelerator; Based on the total weight of the raw materials, the weight percentage of each component is as follows: Raw rubber: 40%-44%; Surfactant: 0.3%-0.6%; Antioxidant: 0.6%-1.0%; Scorch inhibitor and acid absorber: 1.2%-2.0%; Surfactant: 0.2%-0.6%; Processing aids: 1.8%-2.6%; Flame retardant: 10%-14%; Reinforcing agent: 32%-36%; Masterbatch: 2.5%-3.5%; Vulcanizing agent: 2.2%-3.0%; Vulcanization accelerator: 0.8%-1.2%.

2. The flame-retardant, high-voltage resistant insulating rubber material for connectors according to claim 1, characterized in that: The raw rubber is chloroprene rubber.

3. The flame-retardant, high-voltage resistant insulating rubber material for connectors according to claim 1, characterized in that: The activator is stearic acid; The scorch-resistant acid-absorbing agent is active magnesium oxide.

4. The flame-retardant, high-voltage resistant insulating rubber material for connectors according to claim 1, characterized in that: The surfactant is bis-(γ-triethoxysilylpropyl)tetrasulfide.

5. The flame-retardant, high-voltage resistant insulating rubber material for connectors according to claim 1, characterized in that: The flame retardant is melamine cyanurate.

6. The flame-retardant, high-voltage resistant insulating rubber material for connectors according to claim 1, characterized in that: The reinforcing agent is calcined kaolin.

7. The flame-retardant, high-voltage resistant insulating rubber material for connectors according to claim 1, characterized in that: The processing aid is low molecular weight polyethylene wax; The antioxidant is 4-octyldiphenylamine; The sulfiding agent is zinc oxide; The vulcanization accelerator is diethylthiourea.

8. A method for preparing a flame-retardant, high-voltage resistant insulating rubber material for connectors as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Weigh each raw material component according to the stated weight percentage; S2, Plasticizing: Place the raw rubber on a rolling mill and plasticize it until it softens and the surface is smooth, then wrap it around the rollers; S3. Preliminary mixing: Add activators, antioxidants, scorch inhibitors and acid absorbers, and processing aids, and mix well; S4. Final mixing and flaking: Add surfactants, flame retardants, color masterbatches and reinforcing agents, and mix well; Then add vulcanizing agent and vulcanization accelerator, mix well, and then pass through a thin sheet to obtain the compound rubber base material. S5. Vulcanization molding: The compounded rubber substrate is subjected to compression molding and vulcanization at a vulcanization temperature of 140-160℃, a vulcanization pressure of 70-90MPa, and a vulcanization time of 350-450 seconds to obtain the finished product.

9. The method according to claim 8, characterized in that: In step S2, the gap between the mill rollers is adjusted to 1mm, and the raw rubber is softened by passing through the rollers 5-7 times. After wrapping the rollers, the left and right sides are alternately cut to plasticize until the surface is smooth. During plasticizing, the temperature of the mill rollers is controlled not to exceed 50℃. In step S4, after adding the vulcanizing agent and vulcanization accelerator and mixing them evenly, the triangular wrapping and thin-passing operations are performed, and the flat-winding operation is performed before the film is unwound to drive out air bubbles.

10. The method according to claim 8, characterized in that: In step S4, the compounded rubber substrate after sheeting needs to be left at 20-25℃ for 6-10 hours before proceeding to step S5 for vulcanization molding.

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