Composite materials are formed by photo curing compositions containing one or more cyanoacrylates, substantial amounts of one or more fillers (in particular, opaque and/or fibrous fillers such as carbon fibers) as well as particular photoinitiator systems. The photoinitiator system may comprise, for example, a metallocene compound such as a ferrocene in combination with an acylgermane or other photocleavable compound which generates an acyl radical when exposed to light. Complete, deep curing of such compositions to provide composite materials having improved mechanical properties can be achieved, even though the light used to initiate curing may not be capable of penetrating the entire thickness of the composition due to the presence of the filler.

A resin composition capable of providing a film or the like that can suppress coloration even after heating is provided. Further, a molded product, a film, a conductive film, a film capacitor, a polarized material, an electrostatic induction conversion device, and a touch panel using the resin composition are provided. A resin composition including: a copolymer (A) containing a constitutional unit (a1) derived from 1,1-dicyanoethylene and a constitutional unit (a2) derived from a compound represented by the following general formula (I); and a Bronsted acidic compound (B), in which a content of the Bronsted acidic compound (B) in the resin composition is 0.1 to 95,000 ppm by mass.

Provided are a copolymer capable of suppressing coloration even after heating, and a method for producing the copolymer. A copolymer containing a constitutional unit (A) derived from 1,1-dicyanoethylene and a constitutional unit (B) derived from a compound represented by the following general formula (I):

##STR00001##

in which the copolymer includes the following four kinds of triad structures (U-1) to (U-4) composed of the constitutional unit (A) and the constitutional unit (B),

##STR00002##

and a total content of (U-2) and (U-3) in a total amount of the four kinds of triad structures is 5.5 mol % or less.

Provided is a copolymer capable of suppressing coloration even after heating. A copolymer containing a constitutional unit (A) derived from 11-dicyanoethylene and a constitutional unit (B) derived from a compound represented by the following general formula (I):

##STR00001## in which the copolymer includes the following four kinds of triad structures (U-1) to (U-4) composed of the constitutional unit (A) and the constitutional unit (B),

##STR00002## and a total content of (U-2) and (U-3) in a total amount of the four kinds of triad structures is 9.0 mol % or less.