PURPOSE: To obtain the subject new resin exhibiting excellent water-dispersibility and long-term storage stability and having an acid value comparable to that of conventional solvent-type resin without adding a dispersing agent by preliminarily emulsifying water and an alkyd resin and emulsifying the preliminarily emulsified mixture using a specific apparatus.

CONSTITUTION: The emulsifying apparatus to be used in the subject process has the function to introduce a preliminarily emulsified mixture into a flow channel in a chamber and allow the mixture to collide against a flat plane part in the channel or allow the streams of the mixture to collide with each other in the channel to effect the emulsification of the mixture. The objective resin is produced by emulsifying the preliminarily emulsified mixture of water and an alkyd resin using the above apparatus. Concretely, a preliminarily emulsified mixture is supplied under pressure of 5-30kg/cm2 to the clamping part 1 of an apparatus provided with a chamber consisting of clamping parts 1, 2 and disks 3, 4 durable to ultrahigh pressure and the flow of the mixture is divided into two, introduced into the disk 3 and allowed to collide against the plane parts 5, 6 of the disk 4. The pressure of the liquid at the collision is preferably 200-3,000kg/cm2.