Preparation of flame-resistant soft polyurethane foams of reduced smoke density, and melamine/expandable graphite/polyether-polyol dispersions for this purpose

A melamine/expandable graphite/polyether-polyol dispersion comprising:

• from 5 to 100 parts by weight of melamine,
• from 0.1 to 35 parts by weight of expandable graphite,
• from 0.5 to 15 parts by weight of a modified or unmodified ammonium polyphosphate, and
• 100 parts by weight of a polyol component consisting essentially of one or more polyether-glycols, polymer modified polyols selected from the group consisting of graft polyether-polyols and polyurethane/polyether polyol dispersions, or a mixture thereof, having a functionality of from 2 to 3 and a molecular weight of from 3600 to 6500.

A process for the preparation of a flame-resistant, soft polyurethane foam having reduced smoke density, comprising reacting

• a) an isocyanate component comprising an organic polyisocyanate and/or a modified organic polyisocyanate with
• b) a polyol component comprising a high-molecular-weight compound containing at least two reactive hydrogen atoms, and
• c) optionally, a low-molecular-weight chain extender, in the presence of
• d) a flameproofing agent,
• e) a blowing agent
• f) a catalyst and, optionally
• g) assistants and/or additives,
• wherein the flameproofing agent (d) comprises, per 100 parts by weight of the polyol component (b):
• di) from 5 to 100 parts by weight of melamine,
• dii) from 0.1 to 35 parts by weight of expandable graphite, and
• diii) from 0.5 to 15 parts by weight of a modified or unmodified ammonium polyphosphate.

A process for the preparation of a flame-resistant, soft polyurethane foam having reduced smoke density, comprising reacting

• a) an isocyanate component comprising an organic polyisocyanate and/or a modified organic polyisocyanate with
• b) a polyol component selected from the group consisting of a high-molecular-weight polyether polyol containing at least two reactive hydrogen atoms, polyurethane/polyether-polyol dispersions, graft polyether-polyols, and mixtures thereof, and
• c) optionally, a low-molecular-weight chain extender, in the presence of
• d) a flameproofing agent,
• e) a blowing agent,
• f) a catalyst and, optionally
• g) assistants and/or additives,
• wherein the flameproofing agent (d) comprises, based on 100 parts by weight of the polyol component (b):
• di) from 5 to 100 parts by weight of melamine,
• dii) from 0.1 to 35 parts by weight of expandable graphite, and
• diii) from 0.5 to 15 parts by weight of a modified or unmodified ammonium polyphosphate.