Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-11-18
2001-10-23
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S129000, C521S131000, C521S164000, C521S167000, C521S170000
Reexamination Certificate
active
06306920
ABSTRACT:
On account of their low thermal conductivity, polyurethane rigid foamed materials are employed for the insulation of refrigeration and freezing appliances, of industrial installations, of tank farms and pipelines, and in shipbuilding and in the construction industry. A summarised review of the production of polyurethane rigid foamed materials and their use is given in the Kunststoff-Handbuch, Volume 7 (Polyurethanes), 2nd Edition 1983, edited by Dr. Günter Oertel (Carl Hanser Verlag, Munich).
The thermal conductivity of a substantially closed cell polyurethane rigid foamed material depends to a considerable extent on the type of foaming agent or cell gas used. Fully halogenated chlorofluorocarbons (CFCs) have proved to be particularly suitable for this purpose, particularly trichlorofluoromethane (R11), which has a particularly low thermal conductivity. These substances are chemically inert and nontoxic. On account of their high stability, however, fully halogenated chlorofluorocarbons enter the stratosphere, where they contribute to the destruction of the ozone which is present there due to their chlorine content (Molina, Rowland, Nature 249 (1974) 810).
As a replacement for chlorofluorocarbons, the use of hydrofluoroalkanes such as R141b (dichlorofluoroethane) as foaming agents has been proposed (U.S. Pat. No. 5,272,183).
The use of partially fluorinated hydrocarbons (hydrofluoroalkanes) as foaming agents, which still contain at least one carbon-hydrogen bond, has also been proposed (EP 344 537, U.S. Pat. No. 4,931,482). Substances of this class of compounds contain no chlorine atoms and consequently have an ODP value (ozone depletion potential) of zero (by comparison, R11has an ODP of 1). Typical representatives of this class of substances are, for example, 1,1,1,4,4,4-hexafluorobutane (R356) and 1,1,1,3,3-pentafluoropropane (245fa).
In addition, the use of cyclopentane, or cyclopentane in admixture with other alkanes, such as i-butane, n-butane, n-pentane or isopentane, as foaming agents is known from EP 0 421 269.
Depending on the foaming agent used, the polyol formulation has to be modified in order to obtain polyurethane rigid foamed materials of comparable, low thermal conductivity. Polyol formulations would therefore be desirable which would result in rigid foamed materials of similar thermal conductivity when different foaming agent systems are used, without changes in the formulation or changes in the mechanical equipment parameters for the foaming formulation becoming necessary, which are disadvantageous for reasons of cost.
The object of the present invention was therefore to identify a method of producing closed cell polyurethane rigid foamed materials of low thermal conductivity, with which polyurethane rigid foamed materials having a similar, low thermal conductivity can be obtained even when different foaming agent systems are used.
Surprisingly, polyol formulations have now been found which can be foamed using all the aforementioned replacement substances for chlorofluorocarbons, particularly cyclopentane, cyclopentane/i-butane mixtures, cyclopentane/i-pentane mixtures, R 141b and R 245 fa, and which always result in polyurethane rigid foamed materials which have a similar, low thermal conductivity and an outstanding spectrum of properties, and which are particularly suitable for the insulation of refrigeration and freezing appliances. This is particularly advantageous for the processor of such formulations, since on a possible change of foaming agent, e.g. for legal reasons, no special adaptation of mechanical equipment parameters and no change in stockholding is necessary, and a change of foaming agent can thus be made rapidly and costeffectively.
The present invention relates to a method of producing closed cell polyurethane rigid foamed materials having a low thermal conductivity from polyols and polyisocyanates and from foaming agents and optionally from foaming aids, characterised in that the polyurethane rigid foamed material is obtained by the reaction of
A. a polyol component containing
(1) 40-80% by weight of a polyethylene oxide/propylene oxide polyether of molecular weight 300-800 which is based on sucrose or sorbitol,
(2) 3-40% by weight of a polyethylene oxide/propylene oxide polyether of molecular weight 300-800 which is based on an aromatic mono-, di- or polyamine,
(3) 3-40% by weight of a polyethylene oxide/propylene oxide polyether of molecular weight 200-800 which is based on an aliphatic mono-, di- or polyamine,
(4) 3-40% by weight of a linear polyethylene oxide/propylene oxide polyether of molecular weight 500-1500,
(5) optionally other compounds of molecular weight 150 to 12,500 g/mole which comprise at least two hydrogen atoms which are reactive towards isocyanates,
(6) catalysts,
(7) water,
(8) foaming agents from the group comprising alkanes, cycloalkanes, hydrochlorofluorocarbons, hydrofluorocarbons, and
(9) optionally adjuvant substances and/or additives with
B. a polyisocyanate which is optionally modified and which has an NCO content of 20 to 48% by weight.
Polyol formulations which are used according to the invention contain a compound of molecular weight 300 to 800 g/mole which comprises at least two hydrogen atoms which are reactive towards isocyanates. They are obtained by the addition polymerisation of alkylene oxides, such as ethylene oxide, propylene oxide, butylene oxide, dodecyl oxide or styrene oxide for example, preferably propylene oxide or ethylene oxides, with starter compounds. Polyhydric alcohols such as sucrose and sorbitol, as well as mixtures of these alcohols with water, glycerol, propylene glycol, ethylene glycol or diethylene glycol, are used as starter compounds. By means of these polyols which are used according to the invention, the mechanical properties of polyurethane rigid foamed materials which are usually required in practice can be obtained.
The polyol formulations which are used according to the invention additionally contain at least one compound which has a molecular weight of 300 to 800 g/mole and which comprises at least two hydrogen atoms which are reactive towards isocyanates. These compounds are obtained by the addition polymerisation of alkylene oxides, such as ethylene oxide, propylene oxide, butylene oxide, dodecyl oxide or styrene oxide for example, preferably propylene oxide or ethylene oxide, with aromatic mono-, di- or polyamines such as aniline, phenylenediamine, diaminotoluenes (2,3-diaminotoluene, 3,4-diaminotoluene, 2,4-diaminotoluene, 2,5-diaminotoluene, 2,6-diaminotoluene or mixtures of said isomers), 2,2′-diamino-diphenylmethane, 2,4′-diamino-diphenylmethane, 4,4′-diaminodiphenylmethane or mixtures of these isomers.
In addition, the polyol formulations which are used according to the invention contain at least one compound which has a molecular weight of 200 to 800 g/mole and which comprises at least two hydrogen atoms which are reactive towards isocyanates, which are obtained by the addition polymerisation of alkylene oxides, such as ethylene oxide, propylene oxide, butylene oxide, dodecyl oxide or styrene oxide for example, preferably propylene oxide or ethylene oxide, with aliphatic mono-, di- or polyamines such as ethylenediamine, oligomers of ethylenediamine (for example diethylenetriamine, triethylenetetramine or pentaethylenehexamine), ethanolamine, diethanolamine, triethanolamine, N-methyl- or N-ethyldiethanolamine, 1,3-propylenediamine, 1,3- or 1,4-butylenediamine, or 1,2-, 1,3-, 1,4-, 1,5- or 1,6-hexamethylenediamine.
The polyol formulations which are used according to the invention also contain a compound which has a molecular weight of 500 to 1500 g/mole and which contains at least two hydrogen atoms which are reactive towards isocyanates. These are obtained by the addition polymerisation of alkylene oxides, such as ethylene oxide, propylene oxide, butylene oxide, dodecyl oxide or styrene oxide for example, preferably propylene oxide or ethylene oxide, with starter compounds such as water, propylene glycol, ethylene glycol or diethylene glycol.
The
Dietrich Werner
Heinemann Torsten
Klan Walter
Bayer Aktiengesellschaft
Cooney Jr. John M.
Gil Joseph C.
Sloane Carolyn M.
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