Concept for Wood Procurement | Effective Use of Wood
Breakdown of wood raw materials
Use of low-value wood
Trees from forest thinning that facilitate healthy forest growth, trees that are twisted, hollow core or otherwise low in quality, leftover trees from sawmilling or of low-quality trees unfit for sawing, trees of value too low to be used for construction or timber, chips, and used materials to be disposed as waste ------- all these wood materials are useful raw materials for the paper industry (see Fig. 1). Effective utilization of wood materials is sought to the maximum extent in this way so as not to waste the precious forest resources.
Figure1 Composition ratio of pulpwood by source(2022)
Plantation wood
Among these, domestic woods are the low-quality timbers and tinned wood.
Imported woods include forest thinnings, eucalyptus, and acacia planted for pulp production.
Natural wood
Wood from naturally-grown trees. They are harvested systematically according to sustainable forest management plans.
Sawmill residues
The croissant-like flitches that come out of the logs in sawmills to obtain cants for construction purposes are used as raw materials. This is an important source among Japanese raw materials.
Others (forest residue, used wood, etc.)
Branches left by the limbing operation of harvested logs (forest residues) and used wood from torn-down houses and the like.
Use of lumber remnants for woodchips
Traditionally, pulp was made by grinding logs in a machine. Today, the more widely-employed process is the chemical pulping whereby woodchips and chemicals are treated at high temperatures and under high pressures. The use of woodchips has made it possible to use a much wider variety of raw materials. Woodchips are small pieces of wood of sizes around 2 - 4 cm in length and 4 - 5 mm in thickness (Photo 1). Lumber remnants that had traditionally been disposed of or burned can now be used. The effective use of lumber remnants through the increased use of woodchips contributes to the use of precious forest resources without waste.
Column: Can Kenaf replace wood?
One of the raw materials for papermaking is a plant called Kenaf. Some people say that kenaf can replace wood as raw material. But it is difficult to ensure a stable and large supply of kenaf throughout the year, because the harvest is once a year and cultivation of kenaf requires vast land to prevent replant failure, and the annual growth volume of kenaf is almost same as that of eucalyptus. Therefore, it is virtually difficult that kenaf covers much of raw material demand for papermaking. In other words, kenaf is a material suitable for the use according to the purpose, such as enjoying the texture.