Surface protective film laminate, surface protective film and producing method thereof

A method of producing a surface protective film comprising:

• laminating three layers comprising a protective layer made of a thermosetting polyurethane obtained by curing a polyether polyol, an aliphatic isocyanate, and an alcohol-based curing agent in the presence of a non-amine catalyst, a transparent substrate film, and a pressure-sensitive adhesive layer in that order;
• sending a material component containing a polyether polyol, an aliphatic isocyanate, an alcohol-based curing agent, and a non-amine catalyst to a gap between first and second gap maintaining members that are conveyed by a pair of rollers which are disposed apart from each other;
• thermally curing the material component that is held between the first and second gap maintaining members to form the protective layer;
• and forming one of the first and second gap maintaining members as the transparent substrate film,
• wherein the protective layer is a single layer and has a thickness of 100 μm or more and 300 μm or less, the pressure-sensitive adhesive layer is a silicone adhesive, and a ratio of a number of moles of hydroxyl groups included in the alcohol-based curing agent to a number of moles of isocyanate groups of the aliphatic isocyanate or a prepolymer is 1.05 or more and 1.2 or less,
• a mold release film is adhered to surfaces on the side of the protective layer of the surface protective film, the mold release film is a PET film with a thickness of 125 μm on which a silicon treatment was performed, an irregular transfer PET with a thickness of 100 μm, an Ra of 0.186 μm, an Rz of 1.541 μm, and an RSm of 35.61 μm on which a silicon treatment was performed, or an irregular transfer PET with a thickness of 125 μm, an Ra of 0.081 μm, an Rz of 0.586 μm and an RSm of 20.336 μm on which a silicon treatment was performed, wherein a haze value of the surface protective film is 0.1% or more and 40% or less.