Multilayer body and method for producing multilayer body

A multilayer body comprising:

• a metal base comprising a metal base side;
• and a cured layer 1 on the metal base side of the metal base,
• the cured layer 1 having an internal curing ratio of 70 to 90% on the metal base side, and the cured layer 1 having a surface curing ratio of 50 to 65.2% on a side opposite to the metal base side,
• wherein the cured layer 1 is obtained by irradiating a curable composition with an ultraviolet light emitting diode (LED), the curable composition comprising a curable compound comprising an ethylenically unsaturated double bond (C═C) and a polymerization initiator that can initiate polymerization upon irradiation with the ultraviolet LED,
• wherein the curable compound is a bisphenol A-type epoxy(meth)acrylate and the polymerization initiator is an acylphosphine oxide photopolymerization initiator;
• wherein a thickness of the cured layer 1 is 5 to 10 microns (μm);
• wherein the curing ratios are calculated from the equation:
• Curing
• ⁢
• ratio
• [
• %
• ]
• =
• (
• 1
• -
• (
• (
• B
• ′
• /
• A
• ′
• )
• /
• (
• B
• /
• A
• )
• )
• ×
• 100
• wherein in an FT-IR spectrum of the curable composition, peak intensity of a peak assignable to a benzene ring at 1510 cm−1 is peak intensity A and peak intensity of a peak assignable to the ethylenically unsaturated double bond (C═C) at 1410 cm−1 is peak intensity B, and
• wherein in an FT-IR spectrum of the cured layer 1, peak intensity of a peak assignable to the benzene ring at 1510 cm−1 is peak intensity A′ and the peak intensity of the peak assignable to the ethylenically unsaturated double bond (C═C) at 1410 cm−1 is peak intensity B′,
• wherein the internal curing ratio on the metal base side is measured at 0.1× a thickness of the cured layer 1 away from a surface of the cured layer 1 adjoining to the metal base side of the metal base, assuming that a level of the surface of the cured layer 1 adjoining to the metal base side of the metal base is 0 μm, and
• wherein the surface curing ratio is measured at 0.9× a thickness of the cured layer 1 away from a surface adjoining to the metal base side of the metal base, assuming that a level of the surface of the cured layer 1 adjoining to the metal base side of the metal base is 0 μm.