Nitrogen-free and low-nitrogen crosslinking additives for cold-cure flexible slabstock foam having improved compression and aging properties

A process for producing cold-cure flexible slabstock PU foams, comprising:

• reacting at least one polyol component and at least one isocyanate component in the presence of water and at least one tin catalyst,
• wherein nitrogen-containing crosslinkers having an expanded OH number above 1000 mg KOH/g are employed in a total amount of less than or equal to 0.5 parts by weight, based on 100 parts by weight of the at least one polyol component, wherein nitrogen-containing crosslinkers in the context of the present invention have a nitrogen content of >0.5% by weight, measured by Kjeldahl analysis, and
• wherein at least two nitrogen-free or low-nitrogen crosslinkers having a nitrogen content of ≤0.5% by weight, measured by Kjeldahl analysis, are employed in a total amount ≥0.1 parts by weight, based on 100 parts by weight of the at least one polyol component,
• wherein not more than 4 parts by weight of water per 100 parts by weight of the at least one polyol component are employed and wherein, based on the total weight of the at least one polyol component, >50% by weight of cold-cure flexible foam ether polyols having molar masses of >1500 g/mol per OH group are employed and wherein all the crosslinkers employed have a functionality of isocyanate-reactive groups of ≥3,
• wherein isocyanates suitable as the least one isocyanate component include all isocyanates containing at least two isocyanate groups, wherein the isocyanate index is >95 and ≤115, wherein less than 2 parts by weight polyester ether having an OH number of 55 to 57 mg KOH/g per 100 parts by weight of the at least one polyol component is employed, and
• wherein the at least two nitrogen-free or low-nitrogen containing crosslinkers having a nitrogen content of ≤0.5% by weight are provided as a mixture comprising a combination of (i) maltitol and (ii) at least one of diglycerol and triglycerol, or a combination of 40 to 60% by weight of sorbitol and/or maltitol and 15 to 30% by weight of diglycerol and/or triglycerol and 15 to 35% by weight water.