The sponge midsole (sponge insole) of rubber shoes has good softness, elasticity and compression set resistance, plays a cushioning role in rubber shoes, and is an important part of rubber shoes, and its performance directly affects the wearing experience of rubber shoes. With the improvement of environmental awareness and the demand for resource recycling, the application of reclaimed rubber in the midsole of rubber shoe sponge is becoming more and more extensive. Reasonable design of rubber shoe sponge midsole formula containing reclaimed rubber can further improve product quality while reducing costs.
1. Rubber shoe sponge midsole with reclaimed rubber selection skills
The glue content of the midsole formula of rubber shoes sponge is 5%-10%, and low-grade natural rubber is mostly used or used in combination with styrene-butadiene rubber and butadiene rubber. When a large amount of reclaimed rubber is mixed, the reclaimed rubber E4LYY318 is required to have a certain strength and elongation performance and good softness to meet the elasticity and flexibility needs of the sponge midsole. The commonly used reclaimed rubber in the insole of the rubber shoe sponge is tire reclaimed rubber and rubber shoe reclaimed rubber, and some high-end sports shoes can use white natural latex reclaimed rubber in the light-colored sponge midsole, which is easy to match colors and environmentally friendly and does not migrate.
2. The midsole of the rubber shoe sponge is heavily mixed with reclaimed rubber vulcanization system design
The vulcanization system directly affects the performance of the sponge insoles, and a suitable vulcanization system can ensure the vulcanization effect of the midsole of the rubber shoes, thereby improving the durability and stability of the product. The selection of vulcanization accelerator needs to take into account the matching of the foaming rate of the sponge midsole with the vulcanization rate.
When a large number of reclaimed rubber is used to produce the midsole of rubber shoe sponge, sulfur vulcanization should be selected and the amount of sulfur should be increased appropriately, and the after-acting accelerator system with a long induction period should be used, such as accelerator M, accelerator DM and accelerator D, where M:D=1:1, or accelerator DM and accelerator M and accelerator TMTD should be used together. Reclaimed rubber contains a certain amount of zinc oxide, so zinc oxide can be used less or no in the midsole formula of rubber sponge that uses a large amount of reclaimed rubber
3. The midsole of the rubber shoe sponge is heavily mixed with reclaimed rubber foam system design
The foaming system is the key to the elasticity and cushioning performance of the sponge midsole. It is recommended to use inorganic and organic foaming agents in the foaming system, such as the foaming agent H, baking soda and alum, or ammonium bicarbonate and urea as foaming agents. The foaming rate of the rubber in the midsole of the primary vulcanized sponge should be matched with the vulcanization rate of the midsole itself and the vulcanization rate of the outsole, and the vulcanization rate of the outsole should be faster than the foaming rate of the sponge to avoid the problem of convex bottom.
4. The midsole of the rubber shoe sponge is heavily mixed with reclaimed rubber to soften the plasticization system design
When reclaimed rubber is used to prepare rubber material for the midsole of the rubber shoe sponge, liquid coumerone, industrial grease, engine oil, etc. are generally used as softening plasticizers to improve the elasticity and initiation of the sponge insoles.
5. The midsole of the rubber shoe sponge is heavily mixed with reclaimed rubber filling system design
When a large amount of reclaimed rubber is used in the inner sole of the rubber shoe sponge, the filling system mostly uses clay and calcium carbonate, among which the clay can improve the tensile performance and give the sponge good softness, and the calcium carbonate can improve the compression deformation resistance. It should be noted that clay has the effect of delaying vulcanization, so when the amount of clay is large, the amount of vulcanizing agent and accelerator in the formula should be increased appropriately.
6. The midsole of the rubber shoe sponge is heavily mixed with reclaimed rubber anti-aging system design
The commonly used antioxidants in the midsole of the rubber shoe sponge are antioxidants A and RD, and it is recommended to use antioxidant SP in light-colored sponges.
When using a large number of reclaimed rubber to produce rubber shoe sponge midsoles, we must reasonably design the formula, integrate the raw rubber system, foaming system, vulcanization system, softening and plasticizing system, protection system and filler system and other aspects to ensure that the product has good softness, lasting elasticity, compression deformation resistance and aging resistance, so as to provide a strong guarantee for the production of high-quality rubber shoe sponge midsole, reduce more costs, meet different market needs, and improve economic benefits.
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