But it is becoming increasingly difficult for natural fiber papers to meet the severe standards required of the industrial materials that support modern technology. Take heat resistance for example. Photo 1 shows a friction material used in automobile brakes. It is no exaggeration to say that driving safety depends on this paper. Photo 2 shows the separator inside an alkaline battery.
Paper is essentially a thin layer of overlapping fibers.
The quality of the fiber, characteristics of the surface, and pores between the fibers are all designed to meet a variety of purposes, and the size and distribution of pores can be produced as required. One example is gas-sterilization paper. Scalpels and syringes are placed in a paper bag, and after sterilization with gas, they can be stored in ordinary air. They are maintained in their sterilized state because bacteria cannot pass through the paper. In this case, thorough quality control is required because just one hole larger than a bacterium defeats the bag's germ-free capability.