Pencil raw material mainly has the lead penstock needed materials, graphite lead raw material, color lead raw material and the outward appearance decoration needed materials and so on. The lead penstock needed materials mainly include the lumber and the binding agent. The lumber uses in manufacturing the penstock, the requirement texture is honest, the structure is thin and is uniform, nature soft or slightly soft, has brittleness slightly, little contains the resin, the water absorbability is low, the swell-shrink characteristics is small, does not distort. Mainly has the juniperus virginiana (sabina virginiana), the fragrant cedar, the theda wood, the basswood, the alder and so on. The binding agent should have the suitable viscosity, the fluidity and the wettability, after the hardening, the glue line has toughness, is small to the cutting tool damage, has certainly water resistant, heat-resisting, bears the aged performance, under the normal temperature easy to solidify, the firm time is short, non-toxic and so on. Mainly has the animal glue, the polyester sour ethylene emulsion, the thermal melt rubber and so on. Graphite lead raw material and accessory material raw material have the graphite and the clay. The graphite is the coloring agent, uses its creamy and the plasticity, makes the lead to be able to delimit the black trace, the reliable adherency on the paper surface, and can use the rubber to wipe off. Uses the carbon amount high elected, the pellet thin graphite. The clay is the cementing agent, uses its plasticity and cohesiveness, cakes the graphite pellet. The requirement plasticity is good, the iron content is low, agglutination scope wide clay.
