Synthetic fiber first processing agent, synthetic fiber processing agent, aqueous solution preparation method, synthetic fiber processing method, synthetic fibers, short fibers, spun yard and non-woven fabric

A first component of a two component synthetic fiber treatment agent system, the first component comprising a phosphate compound (A), a solvent(S), and optionally a nonionic surfactant (C), wherein

• the first component has a mass ratio of the content of the phosphate compound (A) and the content of the nonionic surfactant (C) such that phosphate compound (A)/nonionic surfactant (C) is 95/5 to 100/0,
• the phosphate compound (A) contains as organic phosphate ester compounds a phosphate ester P1 represented by Formula (1) shown below, a phosphate ester P2 represented by Formula (2) shown below, and optionally a phosphate ester P3 represented by Formula (3) shown below,
• when in a P nucleus NMR measurement made upon performing an alkali over neutralization pretreatment, the total of P nucleus NMR integral ratios attributed to the phosphate ester P1, the phosphate ester P2, the phosphate ester P3, and an inorganic phosphate compound is taken as 100%, the P nucleus NMR integral ratio attributed to the inorganic phosphate compound is more than 0% but not more than 20%,
• in Formula (1), R1 is an alkyl group or an alkenyl group with 15 to 20 carbon atoms and M1 and M2 are each a hydrogen atom or potassium,
• in Formula (2), R2 and R3 are each an alkyl group or an alkenyl group with 15 to 20 carbon atoms and M3 is a hydrogen atom or potassium,
• in Formula (3), R4 and R5 are each an alkyl group or an alkenyl group with 15 to 20 carbon atoms and Q1 and Q2 are each a hydrogen atom or potassium,
• the solvent (S) has a boiling point at atmospheric pressure of not more than 105° C.,
• the nonionic surfactant (C) has a (poly)oxyalkylene structure in the molecule, and
• the first component has a nonvolatile concentration of not less than 20% by mass and not more than 60% by mass.