If 大陸公司 is a separate legal entity to your Hong Kong company, then it is not the assets of the Hong Kong company even the Hong Kong company is holding the shares of this大陸公司. The payment of this machinery is only a payment on behalf of the company in mainland. In this case, Dr. Current Account with 大陸公司, Cr. Bank.
Unless the title of the machinery still remained with the company, then Dr. Plant and Machinery or Office Equipment Cr. Bank