Method for producing optical fiber having formyl groups on core surface thereof

A method for producing a plastic optical fiber having formyl groups on a core surface thereof, comprising the steps of reacting, at a temperature of 45.degree.-60.degree. C. for 5 to 20 minutes, the core surface of a plastic optical fiber, selected from the group consisting of polystyrene, polyacrylic ester, polyester, polyacrylamide, polyvinyl alcohol, polyethylene terephthalate, polycarbonate and copolymers thereof, with a compound represented by Formula (3):

• ##STR16## wherein R.sup.1 represents a hydrogen atom, a lower alkyl group of C.sub.1 to C.sub.3 or a hydroxyl group;
• R.sup.2 represents --(CH.sub.2).sub.n -- and n represents an integer of 0 to 6;
• and R.sup.3 represents a hydrogen atom or an alkyl group of C.sub.1 to C.sub.6, to introduce on the core surface vic-diol groups represented by Formula (4):
• ##STR17## wherein R.sup.1, R.sup.2 and R.sup.3 are the same as above, and then oxidizing the vic-diol groups to introduce formyl groups on the core surface.

A method for producing a plastic optical fiber having formyl groups on a core surface thereof, comprising the steps of reacting, at a temperature of 45.degree.-60.degree. C. for 5 to 20 minutes, the core surface of a plastic optical fiber, selected from the group consisting of polystyrene, polyacrylic ester, polyester, polyacrylamide, polyvinyl alcohol, polyethylene terephthalate, polycarbonate and copolymers thereof, with a compound represented by Formula (6):

• ##STR19## wherein R.sup.1 represents a hydrogen atom, a lower alkyl group of C.sub.1 to C.sub.3 or a hydroxyl group;
• R.sup.2 represents --(CH.sub.2).sub.n -- and n represents an integer of 0 to 6;
• and R.sup.3 represents a hydrogen atom or an alkyl group of C.sub.1 to C.sub.6, to introduce on the core surface alkenyl groups represented by Formula (7):
• ##STR20## wherein R.sup.1, R.sup.2 and R.sup.3 are the same as above, and then oxidizing the alkenyl groups to introduce formyl groups on the core surface.