Patent ID: 7947792

Claim:
A production method of an optical transmission medium comprising the steps of: (A) putting a polymerization initiator, a first polymerizable compound represented by a general formula shown in a chemical formula 1, and a second polymerizable compound represented by a general formula shown in a chemical formula 2 in a tubular container, said second polymerizable compound is capable of generating a homopolymer having a higher refractive index than a homopolymer generated from said first polymerizable compound, a weight W1 of said first polymerizable compound and a weight W2 of said second polymerizable compound satisfying 1/99≦{W2/(W1+W2)}≦⅔; (B) copolymerizing said first and second polymerizable compounds in said tubular container while said tubular container being rotated around a center of a cross-section circle vertically intersecting a lengthwise direction of said tubular container; (C) alternately repeating said steps (A) and (B) for plural times for concentrically forming plural layers from an inner wall of said tubular container toward said center of said cross-section circle, a value of W2/(W1+W2) in said step (A) for Ith time (I: natural number) being different from a value of W2/(W1+W2) in said step (A) for (I+1)th time; (In a general formula in the chemical formula 1, each of R 1 and R 2 is H or D, R 3 is H, D, CH 3 , CD 3 or a halogen atom, R 4 is an alkyl group having 2 to 8 carbon atoms, and a fluorine atom substitutes for H in said alkyl group), (In a general formula in the chemical formula 2, each of R 1 and R 2 is H or D, R 3 is H, D, CH 3 , CD 3 , or a halogen atom, each of X 1 to X 5 is H, D, a halogen atom, or CF 3 , and at least one of X 1 to X 5 is a halogen atom or CF 3 ), wherein an inner wall of a first layer becomes a gel form when copolymerization of said first and second polymerizable compounds for a second layer starts, removing said tubular container from a rotation polymerization device after said first layer is formed, and thereafter heating said first layer, wherein said tubular container is removably attached to said rotation polymerization device.