| abstract |
The present invention is to provide an isocyanate-based adhesive exhibiting excellent adhesiveness, water-resistant adhesiveness, and heat-resistant adhesiveness. An embodiment of the present invention is an isocyanate-based adhesive used for a surface-treated crystalline thermoplastic resin base material, the isocyanate-based adhesive having a value represented by Formula (A) of 2.0 to 70 after being cured by being allowed to stand still under a condition at 23°C and 50%RH for 3 days, and the crystalline thermoplastic resin base material having a value represented by Formula (B) of 2.0 to 30.0. Formula A = JIS − A hardness / strength at break MPa × elongation at break % / 100 Formula B = δ d / δ p + δ p Note that δ p = γ p - γ p0 and δ d = |γ d - γ d0 |, γ p0 is a polar term of surface free energy before the surface treatment, γ p is a polar term of surface free energy after the surface treatment, γ d0 is a dispersion term of the surface free energy before the surface treatment, and γ d is a dispersion term of the surface free energy after the surface treatment. |