| 摘要 |
PROBLEM TO BE SOLVED: To improve ink followability at writing and ink backflow preventiveness in an erected state by adding a thickener and an atactic polypropylene to a volatile retardant liquid and preparing an ink backflow preventive composition. SOLUTION: The ink backflow preventive composition to be filled in an ink end face at an open side of an ink containing tube of a ballpoint pen is prepared by adding a thickener and an atactic polypropylene to a volatile retardant liquid. Its adding amount of the polypropylene is set to 0.2 to 30 wt.% of the total composition. As the polypropylene, a molecular weight of 1,000 to 5,000 is used. As the retardant liquid, a polybutene or α-olefin-cooligomer or their mixture. As the thickener, that selected from a bentonite, a swelling synthetic mica introduced with a quaternary ammonium ion, a metal soap, a mineral fine particles is used. |
