Resin composition and film using same
The present invention is a resin composition characterized by being able to undergo elastic deformation, having little residual strain rate and exhibiting stress relaxation properties. More specifically, the present invention relates to a resin composition wherein the stress relaxation rate (R) and the residual strain rate α, as measured in a prescribed extension-restoration test, are as follows: 20%≤R≤95% and 0%≤α≤3%.
1. 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 (F A0 ), then the amount of strain being maintained for 5 minutes under the extension/holding conditions, after which the tensile force is measured to determine F A (t 5 ), 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.
2. The resin composition according to claim 1 , wherein when the extension is 15 to 20% in the extension-restoration test, the slope of the change in tensile force relative to the amount of strain during restoration and that during extension satisfy the following formula: slope during restoration/slope during extension ≤0.95.
3. The resin composition according to claim 1 , wherein
a stress value measured at 25% extension is a maximum stress value in the extension-restoration test, and
in cases where measurements are started at the point where the extension process is complete in the stress relaxation properties test described below, the tensile force (F B0 ) immediately after completion of the extension process and the tensile force (F B (t 30 )) 30 minutes after completion of the extension process satisfy the following formula:
0.1≤ F B ( t 30 )/ F B0 ≤0.7
wherein a stress relaxation properties test is as follows:
a piece of resin composition having a thickness of 50 μm, a sample shape of a 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 under the conditions described below using a tensile-compression tester in accordance with ISO 3384, and at the point where the extension is complete, the tensile force being measured and defined as the initial tensile force (F B0 ), and 30 minutes thereafter, the tensile force (F B (t 30 )) being measured,
wherein extension process conditions are as follows:
deflection correction being carried out at a force of 0.05 N or lower to eliminate deflection generated when the test piece is attached to a clamp,
speed of testing of 25 mm/min to a 50% extension;
temperature conditions: 23° C.; and
extension/holding conditions: holding for 30 minutes at 50% extension.
4. The resin composition according to claim 1 , wherein even when the tests are repeated two or more times, the resin composition behaves in such a way that the following formulae are satisfied:
20%≤R ≤95%;
0%≤α≤3%; and
R
=
F
AO
-
F
A
(
t
5
)
F
AO
×
100.
5. A film prepared by using the resin composition according to claim 1 .
6. The resin composition according to claim 1 ,
wherein the polyrotaxane is an axial molecule having terminal functional groups, and the polyrotaxane is enclathrated by a cyclic molecular, and
wherein the cyclic molecule is a ringshaped molecule able to be penetrated by a polymer molecule, and the cyclic molecule has one reactive group able to react with a crosslinking agent.