Method for improving the flame, smoke and/or toxicity retardancy in polyisocyanurate / polyurethane (PIR/PUR) comprising materials

A method comprising at least combining and mixing following ingredients to form a polyisocyanurate and/or polyurethane (PIR/PUR) comprising material comprising:

• a polyisocyanate composition comprising one or more polyisocyanate compounds;
• and
• an isocyanate-reactive composition comprising one or more isocyanate-reactive compounds;
• and
• at least one catalyst compound selected from a trimerization (PIR) catalyst and/or polyurethane (PUR) forming catalyst, and
• at least one compound having at least one ethylenically unsaturated moiety and having a number average equivalent weight<160 g/mol, and
• optionally one or more radical initiator compound, and
• optionally a blowing agent;
• and
• optionally one or more surfactants, one or more flame retardants, one or more antioxidants, or combinations thereof;
• and
• characterized in that the amount of compounds having at least one ethylenically unsaturated moiety is at least 2 wt % based on the total weight of all ingredients used to make the PIR/PUR comprising material and the onset temperature for radical polymerization (Tonset) of the combination of the ethylenically unsaturated compound and the radical initiator (if present) is 2° C. up to 40° C. lower than the maximum reaction temperature achieved during the process for making the PIR/PUR comprising material (reaction exotherm (Treaction)), and
• wherein, after forming the PIR/PUR comprising material, the PIR/PUR comprising material comprises 0.2 wt % up to 27 wt % of un-reacted compounds of the at least one compound having at least one ethylenically unsaturated moiety based on the total weight of the PIR/PUR comprising material.