Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1995-01-27
1997-02-11
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
521155, 521163, 521164, 521167, 521170, 521174, C08J 908
Patent
active
056021909
DESCRIPTION:
BRIEF SUMMARY
Owing to their outstanding heat insulation properties, rigid polyurethane foams have been employed for many years for the insulation of appliances for cooling and refrigeration, industrial installations, petrol stations, pipelines, in shipbuilding and for numerous insulating functions in the construction industry.
The thermal conductivity of rigid polyurethane foam, which has to a large extent closed cells, is largely dependent on the type of foaming agent or cell gas used. The per-halogenated chlorofluorocarbons (FCKW) have proved to be particularly suitable for this purpose, especially trichlorofluoromethane (R11), which has a particularly low thermal conductivity. The said materials are chemically inert, non-toxic and non-combustible. Owing to their high stability, however, the perhalogenated chlorofluorocarbons enter the stratosphere, where they are thought to contribute to the breakdown of the ozone present there by reason of their chlorine content (for example, Molina, Rowland Mature 249 (1974) 810; First interim report of the Bundestags-Enquete-Kommission "Vorsorge zum Schutz der Erdatmosph are" [Bundestag Commission of Enquiry, "Provisions for Protection of the Earth's Atmosphere"] dated 02.11.1988, Deutscher Bundestag, Referat Offentlichkeitsarbeit, Bonn).
The use of partly fluorinated hydrocarbons (hydrofluoroalkanes), which retain at least one carbon-hydrogen bond, as foaming agents has already been proposed (see, for example, EP-PS 344 537, U.S. Pat. No. 4,931,482).
Substances of the said class of compounds contain no chlorine atoms and consequently have an ODP value (Ozone Depletion Potential) of zero. (In comparison: R11: ODP=1)
Typical representatives of this class of substances are, for example, 1,1,1,4,4,4-hexafluorobutane (R356) or 1,1,1,2-tetrafluoroethane (R134a).
Furthermore, the use as foaming agents of hydrocarbons such as n- or i-pentane, 2,2-dimethylbutane, cyclopentane or cyclohexane is known.
Owing to their chemical structure, partly fluorinated and pure, that is, unsubstituted, hydrocarbons are highly non-polar and so do not mix well with the polyols conventionally used for producing rigid foam. However, this is an important prerequisite for the conventional technique of production, wherein the polyol and isocyanate components are mechanically mixed with one another.
In addition to the reactive polyether polyol or polyester polyol, the polyol components also contain the foaming agent and the auxiliary substances such as activators, emulsifiers and stabilisers in dissolved form. The polyol component is thus a one-phase mixture.
When the partly fluorinated or pure hydrocarbons are used in the equimolar substitution of conventional foaming agents such as, for example, R11, in commercially available formulations, their low solubility leads to the formation of two phases which cannot be processed further by conventional methods.
The object of the present invention was to employ a polyol component wherein the solubility of the partly fluorinated and pure hydrocarbons is increased, so that they are present as a one-phase mixture in the polyol component.
Surprisingly, it has been found that the solubility of partly fluorinated and pure alkanes is sharply increased in polyols which contain a tertiary nitrogen atom.
The invention provides the use of hydrogen atoms active towards isocyanates and which contain one tertiary nitrogen atom in the molecule, for increasing the solubility of hydrofluoroalkanes and/or pure hydrocarbons in the polyol component during the production of rigid polyurethane foams by reaction with optionally in the presence of
The following are used for the production of the rigid polyurethane foams: isocyanates and a molecule weight as a rule of from 150 to 1500, which contain one tertiary nitrogen atom in the molecule ("polyol component"). These are understood to include, apart from compounds containing amino groups, thiol groups or carboxyl groups, preferably compounds containing hydroxyl groups, particularly compounds containing from 2 to 8 hydroxyl groups, especial
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Eisen Norbert
Lamberts Wilhelm
Thompson-Colon James
Bayer Aktiengesellschaft
Bayer Corporation
Brown N. Denise
Cooney Jr. John M.
Gil Joseph C.
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