The properties and USES of the foamed seal products are largely determined by rubber rubber.
Natural rubber (NR), butadiene rubber (BR) smell is small, often used to make household products;
Styrene butadiene rubber (SBR) has good wear resistance and is used for sole material.
EPDM (EPDM) is commonly used to make automobile seals, sealing rings and insulation products due to its advantages of ozone resistance, heat resistance, weather resistance and soft and soft properties.
NBR (NBR) oil resistant, heat resistant and resilient, mostly used in automobile engine damping materials;
Silicone rubber as can withstand high temperature 300 ℃, used for sealing materials, special environment of expansion connection material and heat insulation, the vibration absorbing material, etc.
Foam sealing strip light quality, excellent elasticity, softness, heat insulation sound-absorbing effect is good, is widely used for sealing, shock absorption, heat insulation, sound insulation, printing and dyeing, etc., in the aviation, automobile, widely used in instruments, meters, household appliances and packaging. The made foaming material as the sole material has the advantage of high slippage.
At present, the research on the formula of foaming seal is mainly concerned with packing, vulcanizing agent and foaming agent.
At present, the research on the process of foaming sealing strip materials mainly involves foaming temperature, foaming time, molding process (mold pressing, extrusion molding) and so on. Foam seal bottom.
Rubber foaming bottom is made from natural or artificial rubber rubber closed or open foaming material made of fabric. Half a century ago, people used this material for sneakers, sneakers, sneakers, liberation shoes, casual shoes, etc. It has good elasticity, good tear resistance, aging resistance, corrosion resistance and electrical insulation.
Solid rubber foam sponge rubber production, its principle is to add people to the selected rubber or add to foaming agent and foaming agent in curing temperature decomposition of foaming agent release gases, surrounded by a rubber foam pore, make form sponge rubber expansion. Decision and the main factors influencing the bubble pore structure are: gas evolution of the foaming agent, gas diffusion velocity in the rubber, rubber viscosity and curing speed, is one of the most critical gas evolution of foaming agent, produce the gas velocity and rubber vulcanization rate matching.
The amount and decomposition rate of the foaming agent.
The hair volume of the foaming agent is the volume of the gas released by the complete decomposition of the foaming agent of the unit mass. The unit is mL/g.
The decomposition rate of the foaming agent is the amount of gas released by the unit time of the foaming agent at a certain temperature.
Since the polymer itself does not change the decomposition mechanism of the foaming agent, it is not possible to measure the amount of foaming agent in the polymer. Usually put a certain temperature of the foaming agent inert dispersant (such as DOP or mineral oil), heating 'collecting gases emitted by a period of time, the drawing gas volume (conversion to a standard under the condition of volume) with the decomposition of foaming agent, heating time down completely after get gas volume divided by the quality of the foaming agent on foaming agent of gas evolution.
Different kinds of foaming agent, different particle size, different temperature, different decomposition rate. In general, the decomposition rate of the foaming agent with low temperature is fast. For the same foaming agent, the particle size is small, the temperature is high, the decomposition rate is fast. The air volume and the decomposition rate of the foaming agent affect the size and structure of the bubble hole, the gas volume is large, the decomposition speed is fast, the bubble hole is large, and the probability of opening the hole is large. The decomposition rate of the foaming agent is matched with the rate of vulcanization.
The matching of the two influences the formation and structure of bubble hole. If the decomposition rate of the foaming agent or the vulcanization speed of the glue material is too different, cannot cooperate, can not foaming. To achieve the matching of the two, to make better rubber products, the choice of foaming agent variety and the rubber vulcanization system is the key. There are two specific methods:
A according to the curing temperature is appropriate to the choice of the decomposition temperature and foaming agent, and then according to the decomposition of foaming agent on the curing temperature speed to adjust the speed of rubber vulcanization, such as using delayed accelerator and other promoters and vulcanization system, adjust the dosage of the promoter can be used to adjust the curing rate;
The second is to select the foaming agent variety and the appropriate particle size according to the curing rate. The particle size of foaming agent is also one of the most important factors to determine the decomposition rate of foaming agent. Particle size decreasing, the increase of specific surface area of the particles, and heat transfer efficiency, the decomposition speed is accelerated, therefore can be adjusted by selecting the appropriate particle size of the foaming agent to the decomposition of foaming agent balance between speed and rubber vulcanization. In addition, strict control of the particle size distribution of the foaming agent is the key to obtain all the bubble holes. The average particle size of the foaming agent AC is between 2 ~ 15fnn and the foaming agent AC of different particle size range.
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