The automotive turbocharging system is constantly exposed to harsh conditions of high-temperature fluctuations and oil and gas erosion. The material of the turbo pipe must not only withstand the continuous high temperatures of the engine, resist the penetration and swelling of fuel and lubricating oil, but also need to firmly bond the inner fluorosilicone layer and the outer methyl silicone rubber during the production of the composite hose. Traditional fluorosilicone materials often have problems such as poor co-sulfidation bonding, insufficient peel strength, and production defects such as hose layer separation and detachment. These are long-term material selection challenges faced by domestic hose manufacturing enterprises. IOTA F5361 is a special fluorosilicone compound for automotive turbocharging hoses. Based on a customized fluorosilicone elastomer formula, it takes into account high-temperature resistance and fuel performance, and realizes direct co-sulfidation bonding with methyl silicone rubber, significantly simplifying the production process of composite hoses.


IOTA F5361 is a fluorosilicone compound material. After adding a vulcanizing agent, it can be molded through hot vulcanization. Its core function is to provide the oil-resistant layer on the inner layer of the turbocharger hose. Many common fluorosilicone gels on the market are resistant to oil and high temperatures, but when combined with ordinary methyl vinyl silicone rubber, they require additional priming and surface activation treatments, which are cumbersome and increase labor costs. Moreover, the bonding interface stability is poor, and they are prone to layer separation and peeling failure under long-term high-temperature cycling. IOTA F5361 is designed with a unique formula, which can directly be co-sulfidated with methyl silicone rubber through pressing without additional surface pretreatment, ensuring stable interface bonding and a peel strength of up to 2.2N/mm, perfectly matching the production process of the wound-type turbocharger hose.


The product appearance is a light yellow semi-transparent rubber material with a density of 1.43g/cm³ and a hardness of 60 Shore A. It is a commonly used hardness specification for the inner layer of the turbocharger hose. The basic mechanical properties are balanced and stable: tensile strength 9MPa, tear elongation 265%, and tear strength 18KN/m. The hose has good toughness during assembly and vibration deformation, and is not prone to cracking or damage, meeting the continuous vibration working conditions of the vehicle.


Under the heat aging test at 225℃ for 72 hours, the hardness only increases by 3 Shore A, the tensile strength change rate -23%, and the elongation rate -15%. The mechanical properties after high-temperature aging are controllable, suitable for the continuous high-temperature environment of the turbo housing. The fuel resistance test: when immersed in Fuel C at 25℃ for 72 hours, the hardness decreases by 11 Shore A, the tensile strength change rate -33%, the elongation rate -21%, and the volume change rate +23%. It maintains the elastic body structure intact in the standard aviation fuel immersion environment, resisting oil and gas penetration swelling, and preventing the inner layer of the hose from bulging or failure.


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Note: All the performance data in the table are typical reference values and are not regarded as the factory acceptance standards. If the product requires higher long-term heat resistance indicators, heat-resistant additives need to be added to the formula to enhance the heat resistance stability.


## Recommended Processing Scheme


Recommended vulcanization system: Add 1.0 part of bis(2,4-dichlorophenylacetyl) peroxide vulcanizing agent (DCBP)
One-stage vulcanization (hot air): 180℃ × 30 minutes
Two-stage vulcanization (hot air): 200℃ × 2 hours


This vulcanization process is suitable for both manual winding and mechanical winding of rubber tubes. Typical rubber tube structure: Inner layer is single-layer fluorosilicone rubber, with the pressing thickness controlled at 0.5 to 1mm, and the outer layer is a multi-layer fabric sandwich of methyl silicone rubber.
If the production line needs to adjust the vulcanization temperature window, the corresponding vulcanization system must be replaced, and the temperature parameters cannot be directly modified. Otherwise, problems such as insufficient crosslinking, product bubbles or scorching may occur.
The two-stage vulcanization is a key process, which can remove small molecules of vulcanization by-products and stabilize the oil and heat resistance of the rubber tube as well as the bonding strength of the composite layer. Omitting the two-stage vulcanization will result in large rubber tube odors, poor compression permanent deformation, and decreased bonding strength at the composite interface. During actual production, the process parameters can be slightly adjusted based on the wall thickness of the rubber tube and the line speed of the production line through small-scale trials.


## Main Application Fields


1. Automotive field: Inner layer of automotive turbocharger hoses with oil-resistant fluorosilicone, intake system hoses, and rubber parts in contact with engine oil and fuel vapor;
2. General mechanical equipment: Industrial equipment with oil-resistant and high-temperature composite rubber hoses, flexible pipeline for oil transportation;
3. Special composite hoses: Multi-layer structure rubber products that require fluorosilicone and methyl silicone rubber to be vulcanized together.


## Processing Practical Considerations


1. Mixing operation: Mix evenly in the open mill and then add the DCBP vulcanizing agent. Thoroughly thin and ensure the uniform dispersion of the vulcanizing agent. Local enrichment of the vulcanizing agent is prone to cause bubbles and early scorching in the product;
2. Co-vulcanization control: Control the temperature matching of the two layers of rubber during the pressing and bonding stage to ensure synchronous crosslinking of the fluorosilicone layer and the methyl silicone rubber, maximizing the peel strength;
3. Thickness control: The recommended pressing thickness for the fluorosilicone layer is 0.5 to 1mm. Excessive thickness may affect heat transfer during vulcanization, resulting in incomplete crosslinking inside;
4. Storage requirements: Store the fluorosilicone mixed rubber in a cool, dark place, away from heat sources, to prevent premature crosslinking. Use the rubber material as soon as it is opened to avoid contamination by impurities that affect the surface quality of the pressing;
5. Small sample verification: Before formal production, it is necessary to conduct small-scale samples for testing the composite peel strength and oil aging performance to confirm the stability of the process before mass production.


## Industry Common Questions


Q: Can IOTA F5361 only be used for winding turbo tubes?
A: The formula development is mainly for manual/ mechanical winding composite rubber tube scenarios. It can also be used for other rubber parts that require fluorosilicone and methyl silicone rubber to be co-vulcanized; other molding methods require prior small sample verification.


Q: What does co-vulcanization mean and why is this rubber not pre-coated?
A: Co-vulcanization is the synchronous crosslinking reaction of two rubbers, with their molecular chains intertwining to form a bonding surface. The IOTA F5361 formula has been specially designed to match the vulcanization activity of methyl vinyl silicone rubber, and after pressing and bonding, they can vulcanize together to form a high-strength interface, eliminating the need for a base coating process, reducing production costs.


Q: What does Fuel C volume change + 23% represent in terms of performance?
A: This is the normal expansion level of fluorosilicone rubber under standard fuel immersion. This brand offers a balance of co-vulcanization capability and oil resistance performance. If the fuel concentration in the working conditions is higher, it is recommended to conduct medium immersion tests in advance to evaluate the performance. 


As domestic automotive components become more domesticated, the demand for substituting turbo tube materials continues to grow. Traditional imported fluorosilicone compound has long delivery time and high procurement cost. Moreover, many domestic fluorosilicone compounds cannot achieve stable co-sulfidation with methyl silicone rubber, which limits the cost reduction of downstream rubber hose manufacturers. IOTA F5361 focuses on the specialized scenario of turbocharger tubes, integrating the advantages of high-temperature resistance, fuel resistance and co-sulfidation technology. It simplifies the manufacturing process of composite rubber hoses and helps rubber product enterprises reduce the difficulty of process debugging. When downstream manufacturers select materials, they need to conduct small sample tests based on actual working temperature, medium type and hose structure, determine the final production process and ensure the stability of large-scale products.