Advances to suppliers

12 Months Ended

Dec. 31, 2018

Prepaid Expense, Current [Abstract]

Advance To Suppliers [Text Block]

6. Advances to suppliers

Balances of advances to suppliers were $2,292,843 and $6,050,531 as of December 31, 2018 and 2017, respectively, which represented prepayments to suppliers for raw materials.