Automotive silicone tube production process

1. Rubber processing
At present, it is generally used directly to mix silica gel, and crosslinking agent and heat stabilizer or colorant are added before use. Generally added in the open mill, but control the roller temperature below 50℃, it is best to use appropriate tooling for its thin pass, in order to promote the compatibility and uniformity between various compounding agents and silica gel.
A, in order to increase the coordination between the color powder (colorant) and silica gel, generally before mixing, the color powder and 110 silica gel (methyl vinyl silica gel, currently domestic 110-2) are mixed and processed into color master glue.
B. Vulcanizing agents commonly used now include:
①DCBP, commonly known as "double 2,4", peroxide double (2, 4-dichlorobenzoyl), paste DCBP is a dispersion of DCBP and silicone oil.
②BP(benzoyl peroxide). Paste BP is BP and 110-2 silicone rubber (1/1) master glue.
③DBPH, is the domestic peroxide vulcanizing agent -- 2, 5-dimethyl-2, 5-bis (tert-butyl peroxyl) hexane -- commonly known as' bis 2, 5 '.
④DCP, diisopropyl peroxide, paste DCP is DCP and 110-2 silicone rubber (1/1) master glue.
C, in order to neutralize the insoluble acid products produced by the high temperature vulcanizing decomposition of peroxide vulcanizing agent, to solve the problem of spraying frost after the silicone tube is parked, the silicone antifrost agent can be appropriately added in the rubber mixing, its main components are: dimethylsiloxane polymer, silicone oil and metal oxide.

2, silicone rubber and fiber fabric calendering processing:
In order to meet the requirements of different performance such as strength and heat resistance of silicone tube to adapt to different use environments and conditions, and ensure the adhesion and compactness between silicone and cloth layer, it is necessary to wipe and paste the fabric and silicone rubber before the tube is formed.
At present, the equipment used for glue hanging is generally four-roller or three-roller calendering machine, and there are relatively backward points to use the processing method of directly bonding the fabric and silicone rubber on the open mill. Sometimes in order to ensure sufficient bond strength between fabric and silicone rubber, it is also necessary to dip the fabric with special adhesive before calendering and then calendering.
Currently used fabrics are generally aramid cloth, vinylon cloth, polyester cloth, glass fiber and so on.

Brief description of calendering operation process:
(1) Start the calender;
(2) Put the fabric and plastic film into the corresponding bench, set the main body of the calender to turn forward, pass the fabric through the whole process of the machine into each guide position to the winding stop machine, and the plastic film through the film coated guide roller reverse through the calender guide roller to stop the calender;
(3) The temperature of the drying roller should be strictly controlled (115±5℃ for no. 1 roller, 115±5℃ for No. 2 roller, 110±5℃ for No. 3 roller and 110±5℃ for No. 4 roller) to ensure that the moisture content of the cord cloth before rolling meets the specified requirements (1%). In case of intermittent operation, the cord should not be parked for more than 4 hours after drying, so as not to absorb water;
(4) Adjust the roll distance of the calender according to the products produced.
(5) Appropriate control of glue supply. The amount of glue supply should be small (each roll ≤10㎏), in order to maintain a certain amount of stacking glue between the roller spacing, reduce the thickness fluctuation;
(6) calendering roller temperature: silicone rubber adhesion cold roller, calendering process in the roller temperature should be lower than the upper and lower roller, when the surface of the rubber corrugated or stick roller, roller temperature should be increased;
(7) The calendering speed should be properly controlled to reduce the stress relaxation of the compound and maintain the uniformity of the thickness;
(8) The cord expansion is controlled by the tension roller to ensure the width of the cord.