The Ryuwon Footwear Factory has improved the quality of vinyl chloride shoe soles by developing the recycling technology, which also contributes to increased production.
The factory has put efforts into research into recycling EVA waste. It is generally impossible to recycle used EVA due to crosslinking and blowing.
In 2013, it made some progress in research into recycling plastic waste, but the finding did not conform to its specific conditions.
Kim Kyong Hui (pictured) at its laboratory carried out in-depth research to suit its actual situation and in the direction of profitability, thereby succeeding in it within one year. She received her first state patent for the finding which realized the recycling of shoe soles.
She proceeded to research and develop printing ink based on domestic materials. She originally developed it with locally-available vinyl perchloride, but its flexibility was unsatisfactory for trainers. To solve this problem, she chose the other material which is cheaper and can ensure flexibility.
Her material- and labour-saving development costs half the previous one and makes it possible to reduce the number of screen plate process from two to one. It also prevents the chapping of the printed part while ensuring the flexibility of shoes. In addition, the application of the laminating printing method has made it possible to print different kinds of patterns in relief while preventing ink from permeating through cloth and to lighten the products as well.
In the course of painstaking efforts, Kim came up with three inventions and two technical findings of national significance and over 30 other inventions and original plans.
She is now working on a new technical innovation with an eye to contributing to shoe production relying on domestic materials.