The production and application of China's EVA foam
materials started late, but due to the excellent processing performance and wide application, the demand growth in recent years has been very rapid, attracting many manufacturers to enter the industry. Benefiting from the stable development of China's manufacturing industry, the upgrading of downstream industries, and the wider application areas will be developed and other favorable factors, China's EVA foam materials market will maintain rapid growth. Hnarts is China's top eva foam sheets suppliers
and is now briefly introduced on EVA foam technology. EVA foaming formula generally consists of the following raw materials: main material, filler, foaming agent, bridging agent, foaming accelerator, lubricant.
The main ingredient is EVA or PE. Of course, in order to improve the physical properties of the product, it is also possible to add some other materials, such as rubber, POE, etc., and even add a little TPR to enhance certain physical properties. The main indicator of EVA* is the VA content, and its level is directly related to the performance of EVA foam products. of course. The specific material used depends on the requirements of the product.
Fillers, currently commonly used calcium carbonate or talc. Its use is to reduce the cost, increase the rigidity of the product, etc., and can also play a role in heat conduction. Generally, the particle size is used as a quality index (of course, the water content is also one side), for example, 120 mesh, 400 mesh, and the like. In principle, the finer the better, of course, the price will be higher.
Foaming agents are generally used to high temperature foaming agents, and the decomposition temperature is more than 220 degrees. There are also low-temperature foaming agents, decomposition temperature of 140 degrees, and medium temperature foaming agents. Because the price difference is not large, and the high-temperature foaming agent is relatively stable, so many of the EVA are now used in high temperature, and also used in combination. The specific dosage can be based on the specific magnification.
The bridging agent, now used is DCP (di-octyl phthalate). Generally, when the material is used, the temperature should be controlled below 120 degrees. For some products that require odor, another bridging agent BIPB can be used, which is generally used in conjunction with TAIC. The amount of DCP used is generally 0.5-0.6 Phr in flat foaming and in-mold small foaming, and generally 0.8-1.0 Phr in injection foaming. Of course, there are also some additions and subtractions, and there are different usages.
There are two types of foaming accelerators, zinc oxide powder, and zinc stearate powder. A single one can also achieve results, and the stability of the product may be better. Zinc oxide can reduce the decomposition temperature of AC to about 160 degrees, which is convenient for production. In general, excessive zinc oxide will shrink the product relatively large. Of course, if too little, the foaming speed is too slow, so *good is not lower than 1.0hr/
Lubricant, generally stearic acid. In fact, it does not have much effect, mainly for the purpose of training materials, not sticking to the machine. It is not good to use more, because it will reduce the friction between the points and reduce the physical properties of most materials.