In metalworking, the amount of sulfur supplied is stabilized in wide temperature and pressure ranges and under an external force, such as a shear force. Thus, a stable iron sulfide film can be formed on the metal surface, and lubricity can be maintained for extended periods. Furthermore, a bulky sulfurized fat or oil with a high molecular weight can be used to form a rigid lubricating oil film with a large oil film thickness on the metal surface and thereby prevent metals from approaching each other. A sulfur-based extreme-pressure agent containing a polysulfide (a) and a sulfurized fat or oil (b) at a mass ratio in the range of 1:0.1 to 1:10. A metalworking fluid containing the sulfur-based lubricating oil composition is also related to.

The present invention provides a water-soluble metalworking oil composition, including: 5.0 to 20.0 mass % of a sulfur compound (A) that is one or more kinds selected from the group consisting of a sulfurized fat and oil and a sulfurized ester and has a kinematic viscosity of 10 to 800 mm.sup.2/s at 40° C.; 0.5 to 20.0 mass % of the nonionic surfactant (B) having an HLB of 6 to 18; 7.0 to 30.0 mass % of an unsaturated fatty acid polymer (C); and an amine compound (D) selected from the group consisting of a tertiary amine and a secondary amine.

The invention relates to aqueous composition comprising water-soluble glycerin-based polyalkylene glycols as synthetic base oils as well as the use of the composition and the glycerin-based polyalkylene glycols as or in metalworking fluids, wherein the glycerin was consecutively alkoxylated in the following order: first with propylene oxide, followed by ethylene oxide and finally with propylene oxide.

An alkylene oxide derivative represented by formula (1), wherein a ratio Mz/Mw of a weight average molecular weight (Mw) and z average molecular weight (Mz) calculated from a chromatogram obtained by gel permeation chromatography measurement of the alkylene oxide derivative satisfies formula (2) below: $\begin{array}{cc}{Z-\left[O-{\left(PO\right)}_a-{\left(PO\right)}_b/\left(EO\right)c\right]-H]}_n& \left(1\right)\end{array}$$\begin{array}{cc}5M_z/M_{w}60& \left(2\right)\end{array}$
where Z, n, PO, EO, a, b and c are as defined herein; a+b+c10, and b/c=1/55/1; (PO).sub.b/(EO).sub.c indicates that PO and EO are randomly added; and a random ratio x of PO and EO satisfies 0.1x1.

A composition comprising water and a polyalkylene glycol having an allyl content of less than 20 eq/g, which composition has reduced foaming properties and preferably a biodegradability of at least 60% as determined using OECD 301F. The polyalkylene glycol can be made by forming a first intermediate comprising an oxypropylene block by reacting propylene oxide with a polyol initiator in the presence of a Double Metal Cyanide catalyst, and then reacting the first intermediate with ethylene oxide in the presence of a KOH catalyst.