Polyisocyanurate comprising foams with long cream time and snap-cure behaviour

1. A process for making a polyisocyanurate comprising rigid foam having a density in the range 50-500 kg/m 3 , said process having a cream time >35 seconds and a snap cure behaviour and comprising combining and mixing at an isocyanate index of at least 200 the following components:

a polyisocyanate composition comprising one or more polyisocyanate compounds;

a catalyst composition comprising at least a trimerization catalyst compound in an amount of at least 50 wt % based on the total weight of all catalyst compounds in the catalyst composition;

an isocyanate-reactive composition comprising at least a low molecular weight (MW) polyol having a MW below 200 g/mol in an amount of 0.1 up to 30 wt % based on the total weight of the isocyanate-reactive composition;

one or more blowing agents comprising at least 50 mol % water based on the total molar amount of all blowing agents;

optionally one or more surfactants, one or more flame retardants, one or more antioxidants or combinations thereof;

wherein the wt % of the trimerization catalyst compounds is <0.5 wt % based on the total weight of the trimerization catalyst compounds and the polyisocyanate composition.

2. The process according to claim 1 , wherein the cream time is >45 seconds.

3. The process according to claim 1 , wherein the isocyanate index is higher than 220.

4. The process according to claim 1 , wherein the wt % of the trimerization catalyst compounds is preferably <0.45 wt % based on the total weight of the trimerization catalyst compounds and the polyisocyanate composition.

5. The process according to claim 1 , wherein the wt % of the trimerization catalyst compounds is <0.30 wt % based on the total weight of the trimerization catalyst compounds and the polyisocyanate composition.