Flexible laminate and flexible display provided with same
A flexible laminate for which increased flexibility and improved durability can coexist, and a flexible display provided with same, are disclosed. The flexible laminate has at least one unit of a laminated structure in which two hard layers closely adhere to each other with at least one intermediate layer therebetween. When the flexible laminate is bent, neutral planes are formed inside each of the hard layers that closely adhere to each other with the intermediate layer therebetween. The flexible laminate satisfies the following expression: a×ln(tan δ×E T /0.01)≥100. In the expression, a is any value ranging from 200 to 2,000, tan δ represents a loss factor for a substance configuring the intermediate layer, and E T represents an elastic modulus (MPa) of the substance configuring the intermediate layer.
1. A flexible laminate, which has at least one unit of a laminated structure in which two hard layers closely adhere to each other with at least one intermediate layer therebetween,
wherein when the flexible laminate is bent, neutral planes are formed inside each of the hard layers that closely adhere to each other with the intermediate layer therebetween, and the flexible laminate satisfies the following expression:
a ×ln(tan δ× E T /0.01)≥100
wherein a is a physical property value inherent to the hard layer, tan δ represents a loss factor of a substance configuring the intermediate layer, and E T represents an elastic modulus (MPa) of the substance configuring the intermediate layer, and is defined by an apparent elastic modulus obtained by dividing a true stress by a true strain after a stress/strain curve is converted into a true stress/true strain curve when a tensile tester performs a tensile test under the condition that room temperature is 25° C. and a strain rate is 0.0525 (1/s);
wherein the hard layer is a substrate selected from a polyethylene terephthalate (PET), polyimide (PI), glass, cycloolefine polymer or a polymethyl methacrylate, and when the substrate is the PET, PI, glass, cycloolefine polymer or the polymethyl methacrylate, a is 500, 500, 1200, 900 or 900, respectively; and
wherein the intermediate layer is a cured product formed of a curable silicone composition that includes
(A) a linear or branched organopolysiloxane having at least one alkenyl group in a molecule on average,
(B) an organopolysiloxane resin,
(C) an organohydrogenpolysiloxane having at least two Si—H bonds in a molecule, and
(D) a hydrosilylation reaction catalyst.
2. The flexible laminate according to claim 1 , wherein in the case in which the flexible laminate is bent, a storage elastic modulus G′ of the substance configuring the intermediate layer at 0.1 Hz and 25° C. is in a range of 1.0 kPa to 1 M (1000 k) Pa, and the storage elastic modulus G′ at 10.0 Hz and 25° C. of the substance configuring the intermediate layer is twice or more the storage elastic modulus G′ at 0.01 Hz and at 25° C.
3. The flexible laminate according to claim 1 , wherein the loss factor tan δ at 1 Hz of the substance configuring the intermediate layer included in the flexible laminate is in a range of 0.2 to 5.0 in a range of −40° C. to 100° C.
4. The flexible laminate according to claim 1 , wherein the elastic modulus E T of the substance configuring the intermediate layer included in the flexible laminate is in a range of 0.050 to 0.200 MPa.
5. The flexible laminate according to claim 1 , wherein the hard layer and the intermediate layer are selected so that the value of a is in the range of 200 to 2000, and the storage elastic modulus G′ of the substance configuring the intermediate layer at 1.0 Hz and −20° C. is three times or more the storage elastic modulus G′ at 1.0 Hz and at 25° C.
6. The flexible laminate according to claim 1 , wherein the organopolysiloxane resin (B) is formed of a unit (M unit) of R 3 SiO 1/2 wherein R represents monovalent organic groups independently of each other and a SiO 4/2 unit (Q unit), and has or does not have a hydroxyl group or a hydrolyzable group.
7. The flexible laminate according to claim 1 , wherein the curable silicone composition is a hydrosilylation reaction curing type.
8. The flexible laminate according to claim 1 , wherein at least one of the hard layers closely adhering to each other with the intermediate layer therebetween is a light emitting layer, and the other of the hard layers is selected from a support layer, an optical functional layer, a protective layer, and a transparent electrode layer.
9. A flexible display provided with the flexible laminate according to claim 8 .