still for framstellning of fibreboard with a banks or central part with relatively law density and with ytskal or ytdelar with relatively high density

摘要

A fiberboard is manufactured having relatively high density skins on a relatively low density core by including urea in at least the surface fibers of a consolidated mat, having a density of less than 35 pounds per cubic foot, and then hot-pressing the consolidated mat at a temperature of at least 525 DEG F. to form a board having high density surface skins.