Solvent-free silicone release composition, release sheet, and method for producing release sheet

A solventless silicone release composition comprising the following components (A), (B), (C) and (E):

• (A) an alkenyl-containing organopolysiloxane containing at least two alkenyl groups per molecule and having a vinyl value of 0.016 mol/100 g to 0.7 mol/100 g and a kinematic viscosity at 25° C. of 80 mm2/s to 500 mm2/s, represented by the general formula (1):
• MαMviβDγDviδTεTviζQη (1)
• wherein M is R3SiO1/2, Mvi is R2PSiO1/2, D is R2SiO2/2, Dvi is RPSiO2/2, T is RSiO3/2, Tvi is PSiO3/2, Q is SiO4/2, R is each independently a C1-C12 substituted or unsubstituted monovalent hydrocarbon group free of aliphatic unsaturation, P is an alkenyl group of the formula:
• —(CH2)a—CH═CH2 wherein a is an integer of 0 to 6, α, β, δ and ζ are each independently an integer of at least 0, not all β, δ and ζ are 0 at the same time, 2≤β+δ+ζ≤50, γ is an integer of 10 to 300, ε is an integer of 0 to 20, and η is an integer of 0 to 10,
• (B) an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms per molecule and having a kinematic viscosity at 25° C. of 2 mm2/s to 500 mm2/s, in an amount to give 1 to 5 moles of silicon-bonded hydrogen atoms per mole of alkenyl groups in component (A),
• (C) an effective amount of a platinum group metal base catalyst, and
• (E) 0.1 to 10 parts by weight per 100 parts by weight of component (A) of an organopolysiloxane containing a crosslinked structure and having fluidity.