Iksan is, among other things, a major rail junction in South Korea, and marks one of the places where, more than 500 years ago, the country stopped being a predominantly Buddhist nation and moved to Confucianism. It is also, in polyurethane terms, a site of catalyst development. Simon Robinson visited Sehotech to find out more.
Sehotech is developing a new range of bismuth catalysts for the polyurethane industry and is in the process of getting them approved, said Min-Gyu Kim, director at the company.
The business, which started operation in Ulsan in Korea’s south-east corner, opened a facility in in Iksan, in the west of the country, because it wanted to expand with new products, Kim explained.
‘It was difficult to do this on the existing cramped site in Ulsan,’ Kim explained. The Iksan site now handles higher volume polyester polyol production.
There are 30 people employed in Iksan on a 15,000 m2 site, and a further 15 work on the 12,000 m2 site in Ulsan.
Sehotech chose Iksan as the location for the new plant because it has good transport links, is a Korean rail hub, and is still largely rural with rice a widespread crop. The area is unusual in Korea because it is very flat.
The company converts diethylene glycol into polyester polyols at Iksan. It uses 10 suppliers, and distils all the materials into 16 fractions which are then processed further in eight batch reactors with capacities ranging between 3 and 15 tonnes.
While Iksan is the firm’s high-volume production business, the polyurethane catalyst business is still based in Ulsan.
Move for room
Initially, the company’s product slate included both tin and bismuth catalysts, but it moved out of tin once these chemicals became more tightly regulated. Now concentrating firmly on bismuth, it has developed several catalysts for PU, but it is taking a little while to get these approved, Kim said.
However, if all goes to plan, a number of new products should be launched at the start of 2018. This launch is likely to see polyols for the rigid insulation market for boards, pipes and spray foam. These products are being developed by an eight-person team in Iksan, all of whom are Korean nationals. The company invests about 20% of its sales in research and development, Kim said. He added that his company bolsters its research efforts with help from Chonbuk National University.
Additionally, Sehotech is involved in polyurethane recycling, and has had a process for this for a number of years, said Lee.
‘The polyols could be used in flexible foam, but this is difficult as the Sehotech process is for rigid products,’ Kim said. It is hard to use recycled polyols from flexible foam because of the complexity of the formulations.
‘The formulation for flexible foam has more components,’ he said. ‘These can become impurities in polyols. Sehotech finds that parts made with the polyols can be used more easily in construction applications.’
The company developed this technology 17 years ago, and started selling it in 2000. ‘We have been developing it as the time has passed,’ Kim added.
Recycled polyols as raw materials for rigid applications would be environmentally sound products, he added. Compared to using virgin polyols, Kim said that these materials can save customers money, give good quality products and improve the environment.
Closing the circle
Sehotech processes 100 tonne/year rigid foam from scrapped domestic refrigerators in Korea. This is done in conjunction with other recycling partners who are commercially interested in the metal components. ‘To save transportation costs, Sehotech takes the foam as compacted pellets,’ said Kim.
The finished polyol can give polyurethanes with the same properties as foam made with virgin polyol, Kim said. After the recycling process is complete, the 100 tonne/year scrap becomes 200 tonne/year polyol, he added, and recycled polyol made this way sells for the same price as virgin polyol.
The company’s rigid polyester polyols business exports to more than 40 countries. Technology developments in the process have continued over the past 17 years, and have led to a process time for the conversion that can be around 30% shorter than other methods.
This makes it cheaper to produce polyester polyols by this method than using alternative approaches, Kim added. The company has chosen not to patent the process, because it would give the competition an idea of how to do the same.
Recycled polyols are only one component of the firm’s polyols offering. Kim said that Sehotech turns over about $20m/year and sells roughly 800 tonne/year product. The company is also looking to get into the polyurethanes systems business, Kim said. He suggested that this could concentrate on product areas such as building insulation, including panel, board and spray foam, he said. ‘We make many products and want to become a systems house.’
‘We started 10 years ago, but it was in very small quantities. Three years ago, we started selling product into the panel, board and spray markets, and have a number of customers,’ said Kim. He expects the business to grow strongly in the next few years. ‘They make up less than 10% of sales, but could be 30% in a few years. Flame retardant products will grow very fast,’ he added.
‘The big refrigerator makers could use our foam. It is good enough, I believe, but engineers are very hard to change,’ Kim concluded.
