Resin composition and film using same

A resin composition

• wherein a cured product of the resin composition is characterized by being able to undergo elastic deformation, having little residual strain rate and exhibiting stress relaxation properties,
• wherein the stress relaxation rate (R) and the residual strain rate (α), as measured in an extension-restoration test, satisfy the following relationships:
• 20%≤R≤95%
• and
• 0%≤α≤3%;
• wherein in the extension-restoration test, a piece of a cured product of the resin composition having a thickness of 50 μm and a shape of No. 6 dumbbell having a width of measured portion of 4 mm and a length of linear portion of 25 mm being subjected to an extension process and then a restoration process under extension process conditions using a tensile-compression tester in accordance with ISO 3384, and the stress relaxation rate (R) and the residual strain rate (α) being calculated using the calculation methods described below,
• wherein extension process conditions are as follows:
• deflection correction is carried out at a force of 0.05 N or lower,
• speed of testing is 25 mm/min from 0 to 25% extension;
• and
• temperature is 23° C.;
• wherein extension/holding conditions holding for 5 minutes at 25% extension;
• wherein restoration process conditions are as follows:
• a speed of testing is 0.1 mm/min until the tensile force reaches 0±0.05 N;
• and
• temperature is 23° C.;
• and
• a stress relaxation rate calculation method of measuring the tensile force when the extension process is complete to determine an initial tensile force (FA0), then the amount of strain being maintained for 5 minutes under the extension/holding conditions, after which the tensile force is measured to determine FA(t5), with the stress relaxation rate (R) being calculated using the following formula:
• R
• =
• F
• AO
• -
• F
• A
• ⁡
• (
• t
• ⁢
• ⁢
• 5
• )
• F
• AO
• ×
• 100
• ;
• wherein the residual strain rate is calculated as the amount of strain being measured at the point where the tensile force in the restoration process reaches 0±0.05 N, and this being defined as the residual strain rate (α);
• wherein the resin composition contains at least (A) a polyrotaxane, (B) an epoxy resin that contains 2 or more epoxy groups and 3 methyl groups per molecule and that has a molecular weight of 500 or higher, and (C) a curing agent, and
• where the proportion of epoxy resin is 30 to 50 parts by mass with respect to 100 parts by mass of polyrotaxane, epoxy resin, and curing agent.