What are the brown paper sack kraft paper made of?

Kraft paper, the composition is conifer wood fiber, after chemical pulping, beating in the pulper, again add rubber, dyes, etc. , the last copy into paper in paper machine. Kraft paper ( 牛皮纸) , used as packaging materials. The intensity is high. Usually brown. Half bleached or fully bleached kraft pulp was light brown, cream or white. Quantitative 80 ~ 120 g/m2. Breaking length is in commonly 6000 m or more. Tensile strength, rupture work and dynamic strength is high. A roll of paper, and a tablet of paper. Is made of sulfate coniferous wood pulp as raw material, after beating, in the long nets manufacture paper with pulp and paper machine. Can be used as cement bag paper, envelope paper, glue sealing paper, tar paper, cable protection paper, insulating paper, etc.