Laminate film and magnetic recording medium using the same

A laminate film comprising:

• (A) a base layer comprising a thermoplastic resin;
• and
• (B) a first film layer which is present on at least one side of the base layer and comprises core-shell particles, each consisting of a core and a shell, and a hydrophilic resin,
• the shell of the core-shell particle having a lower secondary transition point than the core, the core-shell particles having an average particle diameter of 5 to 100 nm, satisfying the following expressions (1) and (2) at the same time,
• 1.01.ltoreq.d.sub.B /dc.sub.B .ltoreq.3.0 (1)
• wherein d.sub.B is an average particle diameter (nm) of the core-shell particles and dc.sub.B is an average diameter (nm) of the cores of the core-shell particles, and
• 0.05.ltoreq.t.sub.B /dc.sub.B .ltoreq.0.8 (2)
• wherein t.sub.B is a thickness (nm) of the first film layer and dc.sub.B is defined as above,
• and producing surface protrusions at a density of 1.times.10.sup.6 to 1.times.10.sup.8 /mm.sup.2 on the surface of the first film layer, and the number of protrusions having a height of not smaller than 0.5 .mu.m being not more than 0.5/mm.sup.2.