Method for producing FRP precursor
Provided is a production method of an FRP precursor. The method includes: a pre-coating step of applying a resin varnish having a filler content of 5 vol % or less in a solid content thereof, to a sheet-shaped aggregate, and a melt-pasting step of melt-pasting a pair of resin films, each having a filler content of 30 vol % or more, to both surfaces of the aggregate, after the pre-coating step.
1 . A method of producing an FRP precursor, the method comprising:
pre-coating a resin varnish having a filler content of 5 vol % or less in a solid content thereof, to a sheet-shaped aggregate;
providing a pair of resin films, each having a filler content of 30 vol % or more; and
melt-pasting the pair of resin films, each having a filler content of 30 vol % or more, to respective sides of the aggregate, after the pre-coating,
wherein in the pre-coating, an volume of solids in the resin varnish to be used is determined by the following formula (1):
0.05
≤
Volume
of
solid
content
of
applied
resin
varnish
(
cm
3
/
cm
2
)
Bulk
volume
of
aggregate
(
cm
3
/
cm
2
)
-
True
volume
of
aggregate
(
cm
3
/
cm
2
)
≤
0.6
.
(
1
)
2 . The method according to claim 1 , wherein the melt-pasting includes a film pressure-welding, and
the film pressure-welding comprises:
a first pressure welding one resin film of the pair of resin films to side of the aggregate; and
a second pressure-welding one surface of the other of the pair of resin films to the other side of the aggregate.
3 . The method according to claim 2 , further comprising preheating the one surface to be subjected to the first pressure-welding of the one resin film and one surface to be subjected to the second pressure-welding of the other resin film, prior to the film pressure-welding.
4 . The method according to claim 2 , further comprising preheating both sides of the aggregate, prior to the film pressure-welding.
5 . The method according to claim 1 , wherein a bulk thickness of the aggregate is 30 μm or more.
6 . The method according to claim 1 , wherein an average particle size of a filler contained in the resin varnish is 0.1 to 10 μm.
7 . The method according to claim 1 , wherein the resin film is a thermosetting resin film.
8 . The method according to claim 1 , wherein the resin varnish has a filler content of 3 vol % or less in a solid content thereof.
9 . The method according to claim 1 , wherein the resin varnish has a filler content of 2.5 vol % or less in a solid content thereof.
10 . The method according to claim 1 , wherein the resin varnish has a filler content of 2.0 vol % or less in a solid content thereof.
11 . The method according to claim 1 , wherein the resin varnish has a filler content of 0.2 vol % or more and 5 vol % or less in a solid content thereof.
12 . The method according to claim 1 , wherein the resin varnish has a filler content of 0.5 vol % or more and 5 vol % or less in a solid content thereof.
13 . The method according to claim 1 , wherein the resin varnish has a filler content of 1.0 vol % or more and 5 vol % or less in a solid content thereof.
14 . The method according to claim 1 , wherein the resin varnish has a filler content of 1.3 vol % or more and 5 vol % or less in a solid content thereof.
15 . The method according to claim 1 , wherein the resin varnish has a filler content of 0.2 vol % or more and 3 vol % or less in a solid content thereof.
16 . The method according to claim 1 , wherein the resin varnish has a filler content of 0.2 vol % or more and 2.5 vol % or less in a solid content thereof.
17 . The method according to claim 1 , wherein the resin varnish has a filler content of 0.2 vol % or more and 2.0 vol % or less in a solid content thereof.
18 . The method according to claim 1 , wherein an average particle size of a filler contained in the resin varnish is 0.3 to 7 μm.
19 . The method according to claim 1 , wherein an average particle size of a filler contained in the resin varnish is 0.5 to 5 μm.