並列摘要
About four decades ago, there were only three main pulping processes used in the pulp and paper industry. These included a pure mechanical grinding process which produced the socalled stone ground wood (SGW), and two chemical processes: acid sulphite and alkaline sulphate (kraft) pulping processes which produced low yield (about 50%) chemical pulps. In the past two decades, there has been a tremendous development in pulping leading to numerous options available today. This is particularly true in the area of sulphate pulping whose development has been accelerated by the environmental and economical restraints. The application of sulphite treatment to mechanical pulping has created pulps with properties between those of mechanical and chemical pulps. This chemical treatment has indeed significantly extended the uses of mechanical pulps (CTMP, CMP) which can be used as the sole furnish of a newsprint or as a replacement for chemical pulps in a paper furnish, depending on the degree of chemical treatment. As a result, the development of very high yield pulps has brought about considerable impact on the Canadian pulp and paper industry. Today, about half of the total Canadian newsprint production contains or is made from very high yield pulps. Although the main use of these pulps is newsprint manufacturing, they find uses in many other products as well, such as printing and writing papers, fluff pulp, tissue, market paper pulp and industrial grades.