Image-transmitting synthetic resin rod and process for producing the same

Claim 2

An image-transmitting synthetic resin rod comprising a reaction product of an acrylic resin ① containing epoxy groups with a material ② having a refractive index 0.15 - 0.35 lower than that of said acrylic resin ①, and distributed in said rod so as to satisfy equation (1) : wherein r is the radial distance from the center axis of the rod (0 ≦ r ≦ r 0 ) , r 0 is the radius of the rod, n r is the refractive index at point r, n is the refractive index at the center of the a rod, g is the distribution constant of the refractive index, and h 4 and h 6 are high order coefficients.

Claim 3

An image-transmitting synthetic resin rod according to claim 1, wherein the acrylic resin ① has a glass transition temperature of at least 70°C.

Claim 4

An image-transmitting synthetic resin rod according to claim 1 or 2, wherein the acrylic resin basically comprises β-methylglycidyl methacrylate.

Claim 5

An image-transmitting synthetic resin rod according to claim 3, wherein the content of S-methylglycidyl methacrylate unit is at least 10 mole %.

Claim 6

An image-transmitting synthetic resin rod according to claim 3, wherein the content of β-methylglycidyl methacrylate unit is at least 40 mole %.

Claim 7

An image-transmitting synthetic resin rod according to claim 1 or 2, wherein the material ② having a lower refractive index is a compound containing fluoroalkyl radicals.

Claim 8

An image-transmitting synthetic resin rod according to claim 6, wherein said fluoroalkyl groups consist of one or more types selected from the group consisting of wherein n is an integer from 1 to 8 and m is an integer from 1 to 4.

Claim 9

A process for producing an image-transmitting synthetic resin rod having a refractive index distribution that satisfies equation (1) wherein r is the radial distance from the center axis of the rod (0 ≦ r ≦ r 0 ), r 0 is the radius of the rod, n r is the refractive index at point r, n is the refractive index at the center of the a rod, g is the distribution constant of the refractive index, and h 4 and h 6 are high order coefficients in a cross section taken perpendicular to the center axis of the acrylic resin rod, which comprises the steps of swelling a rod made of an acrylic resin ① containing epoxy groups with a swelling agent so as to satisfy equation (2) wherein V is the volume of the rod before immersion in o the swelling agent, and V is the volume of the rod after immersion and swelling in said swelling agent until the volume has substantially stabilized and immersing the swollen acrylic resin rod in a reaction solution containing a material ② having a refractive index 0.15 - 0.35 lower than that of said acrylic resin ① and a reactivity to said epoxy groups so as to satisfies equation (3) wherein V' is the volume of the rod after immersion in the reactive solution containing material ② at a constant temperature for a predetermined period of time followed by drying.

Claim 10

A process for producing an image-transmitting synthetic resin rod having a refractive index distribution that satisfies equation (1) wherein r is the radial distance from the center axis of the rod (0 ≦ r ≦ r 0 ), r 0 is the radius of the rod, n r is the refractive index at point r, n is the refractive index at the center of the a rod, g is the distribution constant of the refractive index, and h 4 and h 6 are high order coefficients in a cross section taken perpendicular to the center axis of the acrylic resin rod, which comprises the steps of swelling a rod made of an acrylic resin ① containing epoxy groups with a swelling agent so as to satisfy equation (2) wherein V is the volume of the rod before immersion in o the swelling agent, and V is the volume of the rod after immersion and swelling in said swelling agent until the volume has substantially stabilized and immersing the swollen acrylic resin rod in a reaction solution containing a material ② having a refractive index 0.15 - 0.35 lower than that of said acrylic resin ① and a reactivity to said epoxy groups so as to satisfies equation (3) wherein V' is the volume of the rod after immersion in the reactive solution containing material ② at a constant temperature for a predetermined period of time followed by drying.

Claim 11

A process for producing an image-transmitting synthetic resin structure according to claim 8, wherein said material ② having the lower refractive index has a molecular weight of from 80 to 900.

Claim 12

10 A process for producing an image-transmitting synthetic resin structure according to claim 8, wherein said acrylic resin ① containing epoxy groups is prepared by a bulk polymerization process.

Claim 13

A process for producing an image-transmitting synthetic resin structure according to claim 9, wherein said material ② having the lower refractive index comprises at least one compound selected from the group consisting of compounds represented by formulae [I] through [XII]: (werein n is an integer from 1 to 8 and m is an integer from 1 to 4).

Claim 14

A process for producing an image-transmitting synthetic resin structure according to claim 8, wherein the swelling agent comprises at least one compound selected from the group consisting of methanol, ethanol, 1,1-dimethoxypropane, 2,2-dimethoxypropane, ethylene glycol diethyl ether, 1,1-diethoxyethane, and 1,1-dimethoxycyclohexane, or is a mixture of ethylene glycol dimethyl ether and isopropyl ether.

Claim 15

A process for producing an image-transmitting synthetic resin structure according to claim 8, wherein the reactive solution is prepared by dissolving said material ② having the lower refractive index in at least one compound selected from the group consisting of methanol, ethanol, 1,1-diethoxypropane, 2,2-dimethoxypropane, ethylene glycol diethyl ether, 1,1-diethoxyethane and 1,1-dimethoxycyclohexane, or in a mixture of ethylene glycol dimethyl ether and isopropyl ether.