PVC is widely used in shoes because of its high cost performance. However, the white soles often appear the phenomenon of color change and yellowing, especially in summer high temperature weather. In order to prevent the soles from yellowing, we should first make clear the reasons for the change of color and yellowness. Then the right medicine can be given.
First, precipitate. Because there is a large amount of plasticizer (60 ~ 100PHR) added in shoes, and the compatibility of liquid plasticizer (especially chlorinated paraffin, liquid paraffin, white oil) with PVC is not very good, when the temperature increases, it is easy to precipitate to the shoe material surface, resulting in the shoe sole yellowing.
Solution: use high molecular weight and PVC compatibility plasticizer, such as polyester plasticizer, use high visual calcium powder, increase dispersity and oil absorption value, reduce the use of stearic soap and stearic acid lubricant, use polyol ester lubricant, use part of 2,3 tree fat powder, increase the oil absorption value; add ACR resin, improve plastic The uniformity of the surface makes the surface compact and exudate.
Second, lead pollution. When the temperature is high in summer, lead salt stabilizer, especially powder trisalt and dichroic salt, and so on, when the temperature is high, lead pollution or sulfur pollution will occur in the case of sulfur element (such as packaging carton), which will cause yellow and discoloration.
Solution: replace PVC shoe material with lead salt stabilizer or replace sole calcium zinc stabilizer; reduce contact with sulfur; reduce storage temperature.
Third, the lack of stability of PVC will change from white to yellow to red to brown to black. The stability can be divided into light stability, thermal stability and oxygen stability.
Solutions: replace high-quality stabilizers or increase the amount of stabilizers; add appropriate UV absorbent; add antioxidants, etc.
PVC foaming sole reference formula
Formula 1: PVC 100 dop 80-85, light calcium 60-65 AC-0.5-0.6, foaming regulator 2.0, lead salt compound stabilizer TG-38A) 3.8 PE wax 0.6, stearic acid 1.0, titanium dioxide 2.5.
Formulation II , PVC 100 , DOP 90 , light calcium 70 , AC 0.8 , foaming regulator 2.0 , lead salt stabilizer ( TG - 38A ) 4.0 , PE wax 0.5 , stearic acid 1.2 , titanium pigment or toner .
Formula 3: PVC 100 DIBP85, light calcium 60 AAC TG-75) 0.5, foaming regulator 2.0, calcium zinc compound stabilizer 4.0 Pe wax 0.3, stearic acid 0.5, titanium white or color appropriate.