Resin composition for formation of optical waveguide, resin film for formation of optical waveguide which comprises the resin composition, and optical waveguide produced using the resin composition or the resin film

1. A resin composition for forming an optical waveguide, comprising (A) a polymer having a hydroxyl group and/or a carboxyl group, (B) a (meth)acrylate having a urethane bond, (C) a polyfunctional blocked isocyanate compound, and (D) a radical polymerization initiator, but not comprising (E) a (meth)acrylate having no urethane bond, wherein the component (B) contains a (meth)acrylate having a carboxyl group, a urethane bond, and a polyether skeleton, wherein the component (A) contains a (meth)acrylic polymer that has at least one of structural units represented by the following general formulae (1) and (2) and has a structural unit represented by the following general formula (3):

wherein R 1 represents a hydrogen atom or a methyl group, and X 1 represents a single bond or a divalent organic group having from 1 to 20 carbon atoms,

wherein R 2 represents a hydrogen atom or a monovalent organic group having from 1 to 20 carbon atoms, R 3 represents a hydrogen atom or a methyl group, and X 2 represents a single bond or a divalent organic group having from 1 to 20 carbon atoms,

wherein R 4 represents a hydrogen atom or a methyl group, and R 5 represents a monovalent organic group having from 1 to 20 carbon atoms,

wherein the component (A) further has a structural unit represented by the general formula (4):

wherein R 6 represents a hydrogen atom or a monovalent organic group having from 1 to 20 carbon atoms, and

wherein an amount of the component (A) is from 20 to 75% by mass of the total amount of the components (A) to (C),

an amount of the component (B) is from 20 to 75% by mass of the total amount of the components (A) to (C),

an amount of the component (C) is from 5 to 30% by mass of the total amount of the components (A) to (C), and

an amount of the component (D) is from 0.01 to 10 parts by mass per 100 parts by mass of a total of the components (A) to (C).

2. The resin composition for forming an optical waveguide according to claim 1 , wherein the component (B) further contains a compound having at least one selected from the group consisting of an alicyclic structure, an aromatic ring structure and a heterocyclic structure in the molecule thereof.

3. An optical waveguide comprising a core part and/or a cladding layer that contains the resin composition for forming an optical waveguide according to claim 2 .

4. The resin composition for forming an optical waveguide according to claim 1 , wherein the component (C) is a reaction product of a polyfunctional isocyanate compound and a blocking agent, and the polyfunctional isocyanate compound contains a compound having at least one selected from the group consisting of an alicyclic structure and an aliphatic structure in the molecule thereof.

5. The resin composition for forming an optical waveguide according to claim 1 , wherein the component (D) contains a photoradical polymerization initiator.

6. An optical waveguide comprising a core part and/or a cladding layer that contains the resin composition for forming an optical waveguide according to claim 1 .

7. The optical waveguide according to claim 6 , which has an optical transmission loss of 0.3 dB/cm or less with a light source having a wavelength of 850 nm.

8. The resin composition for forming an optical waveguide according to claim 1 , wherein an acid value of component (B) is from 5 to 200 mgKOH/g.

9. The resin composition for forming an optical waveguide according to claim 1 , wherein the component (B) further contains a urethane (meth)acrylate having polypropylene glycol skeleton.

10. A resin film for forming an optical waveguide, comprising a resin composition for forming the optical waveguide, wherein the resin composition comprises (A) a polymer having a hydroxyl group and/or a carboxyl group, (B) a (meth)acrylate having a urethane bond, (C) a polyfunctional blocked isocyanate compound, and (D) a radical polymerization initiator, but not comprising (E) a (meth)acrylate having no urethane bond, wherein the component (B) contains a (meth)acrylate having a carboxyl group, a urethane bond, and a polyether skeleton, wherein the component (A) contains a (meth)acrylic polymer that has at least one of structural units represented by the following general formulae (1) and (2) and has a structural unit represented by the following general formula (3):

wherein R 1 represents a hydrogen atom or a methyl group, and X 1 represents a single bond or a divalent organic group having from 1 to 20 carbon atoms,

wherein R 2 represents a hydrogen atom or a monovalent organic group having from 1 to 20 carbon atoms, R 3 represents a hydrogen atom or a methyl group, and X 2 represents a single bond or a divalent organic group having from 1 to 20 carbon atoms,

wherein R 4 represents a hydrogen atom or a methyl group, and R 5 represents a monovalent organic group having from 1 to 20 carbon atoms,

wherein the component (A) further has a structural unit represented by the general formula (4):

wherein R 6 represents a hydrogen atom or a monovalent organic group having from 1 to 20 carbon atoms, and

wherein an amount of the component (A) is from 20 to 75% by mass of the total amount of the components (A) to (C),

an amount of the component (B) is from 20 to 75% by mass of the total amount of the components (A) to (C),

an amount of the component (C) is from 5 to 30% by mass of the total amount of the components (A) to (C), and

an amount of the component (D) is from 0.01 to 10 parts by mass per 100 parts by mass of a total of the components (A) to (C).

11. The resin film for forming an optical waveguide according to claim 10 , wherein the component (B) further contains a urethane (meth)acrylate having polypropylene glycol skeleton.