an appropriate amount of particles with the binder resin combination and heating and pressing the treated material alternatively the process can be carried out in a continuous manner by feeding treated particles in the form of a continuous web or mat through a heating and pressing zone defined by upper and lower continuous steel belts to which and through which the necessary heat and pressure are applied whether the process of the invention is carried out in a batchwise or continous manner it is found that the particle board produced using the polyisocyanate and release agent combination of the invention is released readily from the metal plates of the press used in its formation and shows no tendency to stick or adhere to said plates this is in direct contrast to previous experience with the use of polyisocyanates alone as binder resins as discussed above while any of the phosphate release agents defined hereinbefore can be used either along or in combination in the process of the invention it is preferred to use compounds of type str9 in which r is alkyl having at least 3 carbon atoms or aryl substituted by alkyl as hereinbefore defined r 1 is chlorine lower alkoxy mono lower alkyl amino di lower alkyl amino aryloxy or an enol residue of the formula ii and n is an integer from 1 to 2 it is believed that the compounds of formula i act as release agents in accordance with the process of the invention by reason of the ready hydrolysis of.