Addition of antimicrobial/antimold feature and antistatic treatment by electron beam

A plastic which has a high insulation resistance and is apt to build up static causes an electrostatic problem during the process or other problem like an attraction of dust or small particle. Bacteria and fungus are suspended in the air by sticking to the dust/small particle/waterdrop or in the form of spore, and are apt to stick to the substance bearing the static electricity, which may lead to a microbial problem. In order to avoid these problems, an antistatic agent is mixed in a plastic so that the insulation resistance is decreased to prevent the static electricity. Also for the addition of antimicrobial/antimold feature to a plastic, a mixing-in of antimicrobial/antimold agent is adopted. However, problems still remain in the antistatic treatment, such as that an antistatic effect finally becomes invalid due to the loss of the antistatic agent after some time or the surface of the substance becomes viscous and consequently can not maintain the hardness. As to the antimicrobial/antimold treatment, a difficulty remains in selecting a suitable antimicrobial/antimold agent which must be resistant to high temperature during a mixing-in of the agent. In our test, an electron beam-induced technology (EB) by which a non-solvent resin can be hardened at room temperature and provided with a surface hardening is evaluated. An antimicrobial effect was tested by using Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. No live bacteria was observed in a bacteria solution which had been kept overnight in contact with the test film, and the result was proved to successful. As to the antimold effect, a drop of a suspension of 5 different spores including Aspergillus niger was applied to a culture medium, and it was kept in contact with the test film for culturing. On the untreated sample, a growth of the mold was observed approx. 2 weeks later, but on the test film, a growth of the mold was not observed, and the result was proved to be successful. (J.P.N.)