Addition of auxiliary materials in eva foaming formula

Eva foam material has a wide range of applications. On the one hand, it has stronger quality than ordinary foam products. On the other hand, the advantages of safety and reliability make some foam materials can be used in places with high requirements, such as toys suitable for children to play or children's vehicles, including the wheels of strollers. They have many color choices and long service life, and it is also important to play their role. Therefore, we have gained a good reputation and quality evaluation. Next, let's learn about the formula of similar products in Bian Xiao, in addition to the auxiliary products that play a key role.

First, eva foaming formula

EVA foaming formula consists of the following raw materials: main material, filler, foaming agent, bridging agent, foaming accelerator and lubricant.

Obviously, the main material is EVA. Of course, in order to improve the physical properties of the product, some other materials, such as rubber and POE, can be added appropriately. You can even add a little TPR to enhance some physical properties. As for EVA, the main index is VA content, which is directly related to almost all properties of EVA foamed products. Of course. Some can only be foamed with PE. What kind of main ingredients to use depends on the requirements of the product.

At present, calcium carbonate or talcum powder is generally used as filler. Its purpose is to reduce costs and increase the rigidity of products. , but also can play the role of heat conduction. Generally, particle size is used as quality index (of course, water content is also one aspect), such as 120 mesh, 400 mesh, etc. In principle, the finer the better, and of course the price will be higher. The maximum dosage in the formula I have seen is 40Phr (the percentage of the main ingredient). Generally, AC series foaming agents, such as AC-3000H, are used. AC series foaming agent belongs to high temperature foaming agent, and its decomposition temperature is above 220 degrees. There are also low-temperature foaming agents, such as AD-300, whose decomposition temperature is 140 degrees, and medium-temperature foaming agents. Because the price difference is not big, and the high-temperature foaming agent will be relatively stable, so now many old EVA manufacturers have switched to high temperature, and some of them are used together. The amount of AC depends on the specific proportion. DCP is the most widely used bridging agent at present, along with TAIC and PL400. I have used it before. The half-life of DCP is 1 min at 180 and1min at 130. So in general, the temperature should be controlled below 120 degrees. If some products have odor requirements, another bridging agent BIPB can be used, which is usually used in combination with TAIC. The dosage of DCP is generally 0.5-0.6Phr in flat foam and small mold foam, and 0.8- 1.0Phr in injection foam. Of course, there are some appropriate additions and subtractions, and there are also some different usages. At present, there are two kinds of foaming accelerators: zinc oxide powder and zinc stearate powder. We used to use these two combinations here, but now we only use zinc oxide. A single variety can also achieve the effect, 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. We have * * * knowledge here. Generally, the amount of zinc oxide does not exceed 0.2Phr, and the excessive product will shrink a little. Of course, if it is too little, the foaming speed is too slow, and it is best not to be lower than 1.0hr/ lubricant. Generally, stearic acid is used. In fact, it doesn't have much effect, that is, it doesn't stick to the machine when practicing materials. It is not good to use too much, because it can reduce the friction between components and reduce most physical properties. 0.5Phr is recommended, and I will introduce the addition of auxiliary materials in EVA foaming later.

Second, the addition of auxiliary materials in EVA foaming formula

Accessories that can be added to EVA formula are very miscellaneous. Let's just say a few main types.

1, leftover bits and pieces, leftover bits and pieces are just some extra leftover bits and pieces after the product is made. It's all foamed. This kind of thing is a cost killer, which can greatly reduce the production cost and of course affect the physical properties. Almost all of these EVA producers are using it, so I won't go into details.

2, antistatic agent, some products require antistatic function, and EVA foam products have strong static electricity, so it is necessary to add some antistatic agents to the formula. Generally, antistatic agents used in EVA are all mixtures, and the specific composition of MS is very complicated. I don't know for the time being, the dosage is 3%-5%.

3, flame retardant, EVA foam products may need to be flame retardant when used as some packaging materials. Flame retardant can be properly added to the formula to achieve flame retardant effect. The commonly used flame retardants Mg(OH)2 and Al(OH)3 in plastics also have a certain effect on EVA foamed products, but the dosage is relatively large. We all use 12%-20%, but it is of little use for products with high flame retardant requirements. There is a product in Japan that has a good flame retardant effect, but it does not meet the ROHS directive. So, in a word, I don't have any good ideas for those who have high requirements for flame retardant.

4. Fast ripening agent. The foaming process of EVA takes time. If you want to increase the daily output and reduce the energy consumption of products, you can add the quick-ripening agent appropriately to shorten the foaming time. At present, the most common ripening agent in the market is TAIC, to be exact, it should be a bridging agent. Adding a proper amount of TAIC can really shorten the time, but with its addition, the volume of the product will be reduced accordingly, and the time-saving effect is not ideal.

The above example is about the information of eva foaming material formula and the knowledge of adding auxiliary materials, from which we can know that the production of foaming materials involves the selection of raw materials and technical principles, especially the selection of raw materials, which determines the service life and performance characteristics of eva foaming materials, so we should shop around and determine a good plan. Please refer to the above for details. Only by using professional knowledge as much as possible can we ensure satisfactory results and produce various aspects.