The excipients that can be added to the EVA formula are very miscellaneous. Just talk about the main categories.

      1. Leftovers

      Leftovers are the excess tails and edge strips after making products. They are all foamed. This kind of thing is a cost killer. Using it can greatly reduce production costs. Of course, it will also have an impact on physical performance. This type is used by almost everyone who makes EVA, so I won't go into details.

      2. Antistatic agent

      Some products are required to have antistatic function, and EVA foam products themselves have strong static electricity, so some antistatic agents need to be added to the formula. Generally, the antistatic agent used in EVA is a mixture, and the specific composition MS is very complicated. I can't tell clearly at the moment, and the dosage is 3%-5%.

      3. Flame retardant

      EVA foam products used as some packaging materials may need to be flame retardant. Flame retardants can be properly added to the formula to achieve the effect of flame retardancy. Mg (OH) 2 and Al (OH) 3, commonly used flame retardants for plastics, also have certain effects on EVA foam products, but the dosage is relatively large, we all use 12%-20%, but for products with high flame retardant requirements , they also don't work very well. There is a product in Japan that has a very good flame retardant effect, but it does not comply with the ROHS directive.

      4. Quick curing agent

      The EVA foaming process takes time. If you want to increase the daily output and reduce the energy consumption of the product, you can add a quick-cooking agent to shorten the time required for foaming. The most common quick-curing agent on the market now is TAIC, which should be a bridging aid to be precise. Adding an appropriate amount of TAIC can indeed shorten the time, but with its addition, the size of the product will be reduced accordingly, and the time-shortening effect is not very ideal. I don’t know about Fujian, but there are several places in Guangdong that use another fast-cooking agent with a small amount of addition, and the time-shortening effect is quite considerable.

      5. Colorant

      Foaming products are generally colored, so coloring agents need to be added to the formula to adjust the color. EVA foam products can be colored with toner, color glue, and of course it is best to use color masterbatch. MS products cannot be matched by computer, probably because the color changes too much before and after foaming, and the computer can’t match it.

      EVA foam generally has three processes. Large foaming in traditional flat panel, small foaming and injection in mold. (Taiwan name)

      1. Traditional flat foaming

      Now small factories generally use this. The cost of machinery and equipment is relatively low. This process produces plates, which are then made into products through processes such as punching and edging. The foaming conditions are relatively fixed, the temperature is 160-170, the time is determined by the thickness of the mold, generally 90-110s/mm, and the pressure is 150KG/cm2.

      2. Small foaming in the mold

      This process is mainly used in shoe materials. Sports shoes do the first foaming of the secondary midsole. The material trained according to the formula is granulated, weighed and put into the opened mold, and the general shape of the shoe is formed after foaming. The difficulty of this process is the symmetry of the mold and formula, otherwise it is difficult to control the magnification and hardness at the same time. Often the size is qualified, but the hardness is not enough. The hardness is enough and the size is too small. The foaming conditions of this process are relatively flexible, depending on the shape and structure of the product, of course, mainly due to the change of time. The temperature does not vary much. Not to mention stressful conditions. Speaking of the secondary midsole, let’s introduce the second molding here. Grind off the skin of the previously foamed rough embryo, press it into the finished product mold, and form the product through two steps of heating and cooling. The heating temperature is more suitable at 125-135, the pressure is 50KG/cm2, and the water is cooled after heating for a certain period of time. Take it out to be the second midsole. The bottom size of this kind of compression is relatively stable, and the physical properties are relatively better.

      3. Injection

      Injection technology should be the mainstream in the future. A process is done to become a product. It's just that the precision of the mold is higher. The principle is similar to injection molding in the plastics industry. It's just that injection molding is to open the mold immediately, and the mold temperature is different. That is to say, the injection of EVA is nothing more than adjusting the mold temperature and opening time of plastic injection molding. It seems that a friend from Shanghai called me last time, and later let his injection molding machine be used to make foam baby car wheels. Most of the models of well-known sports shoes are made in this way. Compared with other methods, the efficiency is really poor.

      Explain in detail how to add auxiliary materials in the EVA foaming formula, and tell the readers about EVA knowledge through the explanation. Chfine has been cultivating in the field of EVA luggage for many years and has rich professional knowledge. If you have any questions, please feel free to consult.