Expansible mixtures devoid of isocyanates exhibiting improved fire behaviour
Foamable compositions which are free of isocyanates, which exhibit low shrinkage, low propensity toward crack formation, and which display good flammability resistance, are prepared from blowing agent-containing compositions of alkoxysilane-terminated prepolymers derived from a polyol component which contains one or more halogenated polyols.
1. A one component moisture-curable isocyanate-free foamable composition, comprising:
(A) at least one isocyanate-free, alkoxysilane-terminated prepolymer having silane end groups of the formula 3
where
A 1 is an oxygen atom, an N—R 5 group or a sulfur atom,
R 5 is a hydrogen atom, an alkyl, cycloalkyl, alkenyl or aryl radical having 1-10 carbon atoms, or a —CH 2 —SiR 3 z (OR 4 )) 3-z group,
R 3 is an alkyl, cycloalkyl, alkenyl or aryl radical, having 1-10 carbon atoms,
R 4 is an alkyl radical having 1-2 carbon atoms or an ω-oxaalkylalkyl radical having a total of 2-10 carbon atoms and
z is 0 or 1,
wherein said prepolymer incorporates a polyol component comprising at least one halogen-containing polyol, said halogenated polyol containing on average at least four halogen atoms in each halogenated polyol molecule and
(B) at least one blowing agent comprising a mixture of hydrocarbons having 3 to 5 carbon atoms and a polar fluorinated hydrocarbon blowing agent present in 50 weight percent or more based on the weight of the blowing agent, and
wherein a foam prepared from the composition is free of cracks when foamed in a model join which consists of 2 wooden boards having the dimensions 1×15×15 cm and 2 plastic beams having the dimensions 2×2×17 cm.
2. The composition of claim 1 , wherein the A 1 in the formula [3] is part of a urea or urethane unit.
3. The composition of claim 1 , which comprises prepolymers in whose preparation the following components have been used:
a) 10-70 parts of a polyol component containing halogenated polyols, and optionally, further, non-halogenated polyols,
b) 10-70 parts of diisocyanates and/or polyisocyanates, and
c) 10-70 parts of organofunctional alkoxysilanes,
these parts being parts by weight exclusive of other composition components.
4. The composition of claim 3 , wherein component b) consists of tolylene diisocyanate.
5. The composition of claim 3 , wherein the polyol component comprises 20-100% by weight of halogenated polyols.
6. The composition of claim 2 , which comprises prepolymers in whose preparation the following components have been used:
a) 10-70 parts of a polyol component containing halogenated polyols, and optionally, further, non-halogenated polyols,
b) 10-70 parts of diisocyanates and/or polyisocyanates, and
c) 10-70 parts of organofunctional alkoxysilanes,
these parts being parts by weight exclusive of other composition components.
7. The composition of claim 1 , wherein the halogen substituents of the halogenated polyols are selected from the group consisting of bromine, chlorine, and mixtures thereof.
8. The composition of claim 1 , which is free of an effective moisture cure promoting amount of tin-containing condensation catalysts.
9. The composition of claim 8 , which comprises prepolymers in whose preparation the following components have been used:
a) 10-70 parts of a polyol component containing halogenated polyols, and optionally, further, non-halogenated polyols,
b) 10-70 parts of diisocyanates and/or polyisocyanates, and
c) 10-70 parts of organofunctional alkoxysilanes,
these parts being parts by weight exclusive of other composition components.
10. The composition of claim 1 , wherein z is 1.
11. The composition of claim 1 , wherein R 3 and R 4 are methyl.
12. The composition of claim 1 , wherein the prepolymer of the alkoxysilane-terminated prepolymer consists of a polyurethane prepolymer prepared by reacting:
a) one or more polyether polyols, at least one of which is halogenated, with
b) at least one di- or polyisocyanate.
13. The composition of claim 12 , wherein component b) consists of toluene diisocyanate.
14. A process for preparing the foamable composition of claim 1 , wherein the prepolymer is prepared at least partly in a pressure vessel.
15. The process of claim 14 , wherein the prepolymer is prepared completely in the same pressure vessel from which the foamable composition will be exuded.
16. A pressure vessel containing a foamable composition of claim 1 .
17. A pressure vessel containing a foamable composition of claim 8 .
18. A pressure vessel containing a foamable composition of claim 2 .
19. A pressure vessel containing a foamable composition of claim 3 .
20. A pressure vessel containing a foamable composition of claim 5 .