RIGID POLYURETHANE FOAMS COMPRISING A SILOXANE RICH NUCLEATING AGENT
The present technology provides a method of manufacturing a polyurethane foam having a low thermal conductivity from a foam formulation comprising a polyol, an isocyanate, a polyurethane catalyst, a surfactant, water, and a siloxane rich composition. The siloxane rich composition may act as a nucleating agent to reduce the cell size of the foams and may reduce its thermal conductivity.
1 . A composition for use as an additive in a polyurethane foam formulation, the composition comprising a siloxane rich compound of the formula
M 3 a D 3 b D 4 c T d Q e (II)
where
M 3 is a trialkyl end-cap unit R 3 R 4 R 5 SiO 1/2 —;
D 3 is a dialkyl unit —O 1/2 R 6 R 7 SiO 1/2 —;
D 4 is a alkyl unit —O 1/2 R 8 R 9 SiO 1/2 —; T is —O 1/2 Si(O 1/2 —) 2 R 10 ;
Q is Si(O 1/2 —) 4 ;
R 3 , R 4 , R 6 , R 7 , R 8 , and R 10 are independently fluorine, phenyl, or C1 to C10 alkyl groups, eventually fluorine or phenyl partially or fully substituted;
R 5 is fluorine; phenyl; or C1 to C10 alkyl groups optionally partially or fully substituted with fluorine or phenyl; or —R 11 —O m —(CH 2 —CH 2 —O) q (CH 2 —CH(CH 3 )—O) p —R 12 ;
R 9 is —R 11 —O m —(CH 2 —CH 2 —O) q (CH 2 —CH(CH 3 )—O) p —R 12 ;
R 11 is C1 to C10 hydrocarbon group;
R 12 is hydrogen, phenyl, fluorine, or a C1-C8 hydrocarbon group, in embodiments fluorine or phenyl partially or fully substituted and optionally interrupted by urethane, urea or carbonyl groups;
a and b are independently from 0 to 30;
c, d, and e are independently from 0 to 5;
m is 0 or 1;
q and p are independently from 0 to 10;
with the condition that is at least 1;
with the proviso that the siloxane rich compound has a silicon content by weight of at least 25%.
2 . The composition of claim 1 where the siloxane rich compound or mixture of has a number average molecular weight between 200 and 3000 dalton.
3 . The composition of claim 1 where the siloxane rich compound or mixture of has a number average molecular weight between 300 and 2500 dalton.
4 . The composition of claim 1 where the siloxane rich compound or mixture of has a number average molecular weight between 450 and 2000 dalton.
5 . The composition of claim 1 where the siloxane rich compound or mixture of has a silicon content by weight above 28%.
6 . The composition of claim 1 , wherein the siloxane rich compound or mixture of has a silicon content by weight above 28% up to 32%.
7 . The composition of claim 1 where the siloxane rich compound or mixture of has on average 2 or less reactive groups per molecule that can react with isocyanate.
8 . The composition of claim 1 where the siloxane rich compound or mixture of has on average less than 2 or no reactive groups that can react with isocyanate.
9 . The composition of claim 1 where subscript a of the siloxane rich compound is at least equal to 1.
10 . The composition of claim 1 , wherein the siloxane rich composition is based on a distribution of molecular weight that contains 2.5% or less by weight of siloxane based species having a molecular weight below 400.
11 . The composition of claim 1 , wherein the siloxane rich composition contains about 5% or less by weight of cyclic siloxane species having 3 to 6 siloxane groups selected from hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6).
12 . A process for producing a polyurethane foam by reacting the different components of a formulation comprising:
a polyol;
an isocyanate;
a catalyst;
a surfactant;
a physical blowing agent; and
a siloxane rich composition of claim 1 .
13 . The process of claim 12 comprising the siloxane rich composition or mixture in an amount of at least 0.02% by weight over the total formulation components weight excluding physical blowing agents.
14 . The process of claim 12 comprising the siloxane rich composition or mixture in an amount of at least 0.03% by weight over the total formulation components weight excluding physical blowing agents.
15 . The process of claim 12 comprising the siloxane rich composition or mixture in an amount of at least 0.05% by weight over the total formulation components weight excluding physical blowing agents.
16 . The process of claim 12 comprising the siloxane rich composition or mixture in an amount of 3% by weight or lower over the total formulation components weight excluding physical blowing agents.
17 . The process of claim 12 comprising the siloxane rich compound or mixture in an amount of about 0.05% by weight to about 3% by weight over the total formulation components weight excluding physical blowing agents.
18 . The process of claim 12 where the siloxane rich composition or mixture of is added in a formulated pre-blend to be mixed with a isocyanate component to produce a polyurethane foam used as thermal insulation material.
19 . The process of claim 12 , where the siloxane rich composition or mixture of is added as a separate component on a foam dispensing unit to produce a polyurethane foam used as thermal insulation material.
20 . The process of claim 12 where the siloxane rich composition or mixture of is added to an isocyanate component to be mixed with isocyanate reactive ingredients to produce a polyurethane foam used as thermal insulation material.
21 . The process of claim 12 where the siloxane rich composition or mixture of is added in the polyurethane foam formulation in addition to a surfactant, optionally siloxane containing, with the siloxane containing portion of such surfactant if present having a silicon content lower than 25% and a number average molecular weight above 2000 dalton.
22 . The process of claim 12 , wherein the process forms a rigid or semi-rigid polyurethane foam.
23 . The process of claim 22 , wherein the rigid or semi-rigid polyurethane foam has a density between 10 and 100 kg/m 3 and at an isocyanate index between 100 and 500.
24 . A polyurethane foam formed from the composition of claim 1 .
25 . The polyurethane foam of claim 23 , where the foam is a rigid or semi-rigid polyurethane foam has a density between 10 and 100 kg/m 3 and at an isocyanate index between 100 and 500.
26 . The polyurethane foam of claim 24 , where the foam has an initial thermal conductivity of about 23 mW/m·K or less at a mean temperature of 0 to 30° C.
27 . A thermal insulation material comprising the polyurethane foam of claim 25 .
28 . An article comprising the polyurethane foam of claim 24 .