Resin-containing sheet, and structure and wiring board using same
Provided are: a resin-containing sheet in which not only the mechanical strength of a cellulose nanofiber nonwoven fabric but also the flexural resistance of a substrate are improved; and a structure and a wiring board which include the same. The resin-containing sheet includes: a specific cellulose nanofiber nonwoven fabric ( 11 ); a fixing agent ( 2 ) which fixes together fibers ( 1 ) in the cellulose nanofiber nonwoven fabric ( 11 ); and a resin ( 3 ) which is in contact with the cellulose nanofiber nonwoven fabric ( 11 ) and the fixing agent ( 2 ), wherein the storage modulus of the fixing agent ( 2 ) is higher than that of the resin ( 3 ). The structure is obtained by tightly adhering the resin-containing sheet to a substrate. The wiring board includes this structure.
1. A resin-containing sheet comprising:
a cellulose nanofiber nonwoven fabric which is constituted by a single layer or not more than three plural layers comprising at least one cellulose fine fiber layer that contains regenerated cellulose fine fibers in an amount of not less than 70% by mass, said cellulose nanofiber nonwoven fabric satisfying all of the following requirements (1) to (3):
(1) fibers constituting said cellulose fine fiber layer has a specific surface area fiber diameter of 0.20 μm to 1.0 μm,
(2) the air permeation resistance is 1 s/100 ml to 40 s/100 ml, and
(3) the film thickness is 8 μm to 22 μm;
a fixing agent which fixes together said fibers in said cellulose nanofiber nonwoven fabric; and
a resin which is in contact with said cellulose nanofiber nonwoven fabric and said fixing agent,
wherein the storage modulus of said fixing agent is higher than that of said resin.
2. The resin-containing sheet according to claim 1 , wherein the glass transition temperature of said fixing agent is higher than the glass transition temperature or the softening temperature of said resin.
3. The resin-containing sheet according to claim 1 , which is obtained by fixing together said fibers of said cellulose nanofiber nonwoven fabric using a fixing agent composition and subsequently impregnating the thus fixed cellulose nanofiber nonwoven fabric with a resin composition.
4. The resin-containing sheet according to claim 3 , wherein said fixing agent composition has a viscosity of 1 Pa·s or less.
5. A structure obtained by tightly adhering the resin-containing sheet according to claim 1 to a substrate.
6. A wiring board comprising the structure according to claim 5 .