Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-09-03
2001-08-28
Cooney, Jr., John M. (Department: 1711)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C544S401000, C564S336000, C564S343000, C564S344000, C564S349000, C568S583000, C568S584000, C568S608000
Reexamination Certificate
active
06281393
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to polyols useful for preparing water blown polyurethane foams. This invention particularly relates to Mannich polyols useful for preparing water blown polyurethane foams.
It has long been known to prepare rigid polyurethane foams by the reaction of a polyisocyanate with a hydroxyl-terminated polyester or poly(oxyalkylene)ether having a hydroxyl number within the range of from about 350 to about 900. One group of polyols useful for preparing such foams includes the nitrogen-containing polyols described in U.S. Pat. Nos. 3,297,597, 4,137,265, and 4,383,102 ('102). The nitrogen containing polyols which are prepared by alkoxylation of the reaction product of a phenol, alkanolamines and formaldehyde, such as those disclosed in '102 above, shall be hereinafter referred to as Mannich polyols. It has been reported in the literature that polyurethane foam prepared from these polyols is characterized by a greater inherent fire retardancy and good dimensional strength when extraneous fire retardants are employed.
One area of use for such polyols has been in spray foams systems used in roof and pipe insulation applications. The equipment normally used for the industrial application of sprayed urethane foam uses “double acting” positive displacement pumps which have the advantage of supplying an accurate component ratio in a continuous stream. A major disadvantage of this metering system is that it will function reliably only if the B-component has a viscosity of less than 1,000 centipoise at ambient temperature. At higher viscosities, cavitation can occur on the B-component side, resulting in a component ratio change which can affect the foam product quality.
Typically, in the past, the formulations used to prepare spray systems have included halocarbon blowing agents. In the present, the use of many of the traditional blowing agents have been discontinued, or phased out, because of the belief that they contribute to the destruction of the ozone layer which limits the amount of ultraviolet radiation which penetrates the atmosphere. This has resulted in a search for alternative blowing agents such as water.
While water is a useful blowing agent in many types of polyurethane foam, it does not have all of the properties of the halocarbon blowing agents which it has replaced. For example, one disadvantage of water as a blowing agent in polyol formulations including Mannich polyols is water does not reduce the viscosity of Mannich polyols as effectively as halocarbon blowing agents. As stated above, attempting to make foams with formulations which are too high in viscosity can cause problems with some kinds of foam making equipment. Therefore, it would be desirable in the art of preparing water blown polyurethane foams from formulations including Mannich polyols to use an ultra low viscosity Mannich polyol of sufficiently low viscosity to avoid handling problems such as cavitation problems with foam forming equipment.
SUMMARY OF THE INVENTION
In one aspect, the present invention is a process for preparing a Mannich polyol having a viscosity of from 300 to 3,500 cps (0.3 to 3.5 Pa*s) at 25° C. comprising the steps of admixing a phenol, an alkanolamine, and formaldehyde to prepare a Mannich base and then alkoxylating the mannich base with an admixture of ethylene oxide and propylene oxide under reaction conditions sufficient to prepare a Mannich polyol.
In another aspect, the present invention is a Mannich polyol having a viscosity of from 300 to 3,500 cps (0.3 to 3.5 Pa*s) at 25° C.
In still another aspect, the present invention is a polyurethane foam formulation comprising a polyisocyanate A side and a B side including a Mannich polyol having a viscosity of from 300 to 3,500 cps (0.3 to 3.5 Pa*s) at 25° C.
In another aspect, the present invention is a polyurethane foam comprising a polyurethane foam prepared with a polyurethane foam formulation including a polyisocyanate A side and a B side including a Mannich polyol having a viscosity of from 300 to 3,500 cps (0.3 to 3.5 Pa*s) at 25° C.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
One embodiment of the present invention is an ultra low viscosity Mannich polyol having a viscosity of from 300 to 3,500 cps (0.3 to 3.5 Pa*s) at 25° C. The Mannich polyols of the present invention are prepared by admixing a phenol, an alkanolamines, and a formaldehyde mixed in molar ratios resulting in an initiator which can be alkoxylated to prepare polyols that have a nominal functionality of from 3 to about 5.5. For purposes of the present invention, the nominal functionality of polyols of the present invention is equal to the theoretical functionality of the initiator. For example, if unsubstituted phenol and diethanolamine are used with formaldehyde to prepare a Mannich initiator of the present invention in a molar ratio of 1:3:3, the nominal functionality of the resulting polyol is 7 because there are three sites on phenol for formaldehyde to bond and each of those sites is subject to bonding with diethanolamine which is itself di-hydroxy functional. Therefore, such a polyol is 7 functional because each of the 3 diethanolamine results in 2 OH groups and the sum of those 6 OH groups and the original phenolic OH group equals 7.
The Mannich initiators of the present invention are alkoxylated using a mixture of ethylene oxide and propylene oxide. Using a mixture of ethylene oxide and propylene oxide to alkoxylate these initiators allows for the production of a Mannich polyol with comparatively very low viscosities (hereinafter ultralow viscosity Mannich polyols). The ultra low viscosity Mannich polyols of the present invention preferably have a viscosity of from 300 to 1500 cps (0.3 to 1.5 Pa*s), and more preferably have a viscosity of from 300 to 1000 cps (0.3 to 1.0 Pa*s).
Care should be used when preparing the Mannich polyol initiators of the present invention to use the appropriate molar ratios of the phenols, alkanolamines, and formaldehyde to achieve the desired nominal functionality. The preferred ratio of phenol and formaldehyde for preparing the Mannich polyols of the present invention is from 1:1 to 1:2.2. More preferably the ratio of phenol to formaldehyde is from 1:1.5 to 1:2.
The preferred molar ratio of formaldehyde to alkanolamine for use with the processes of the present invention is 1:1. Additional quantities of alkanolamines can be used in preparing the initiators of the present invention, but are neither required nor usually desirable. Use of additional alkanolamines promotes the formation of polyols resulting from the alkoxylation of the alkanolamine. For example, wherein the alkanolamine is diethanolamine and it is used in excess of the molar ratios specified above and not removed prior to alkoxylation, it can be alkoxylated to form a triol. The presence of such amine initiated polyols can result in lower viscosities of the resulting polyol mixtures, but can also lower average functionality which is sometimes undesirable. Use of less than a 1:1 molar ratio of alkanolamine to formaldehyde can also result in Mannich polyol initiators having higher nominal functionalities. Preferably, the Mannich polyol initiators of the present invention are prepared using a molar ratio of phenol to alkanolamine to formaldehyde of from 1:1:1 to 1:2.2:2.2, more preferably from 1:1.5:1.5 to 1:2:2, and most preferably 1:2:2.
Phenols which can be used to prepare the present invention include: o-, m-, or p-cresols, ethylphenol, nonylphenol, p-phenylphenol, 2,2-bis(4-hydroxyphenol) propane, beta-naphthol, beta -hydroxyanthracene, p-chlorophenol, o-bromophenol, 2,6-dichlorophenol, p-nitrophenol, 4-nitro-6-phenylphenol, 2-nitro-4-methylphenol, 3,5-dimethylphenol, p-isopropylphenol, 2-bromo-4-cyclohexylphenol, 4-t-butylphenol, 2-methyl-4-bromophenol, 2-(2-hydroxypropyl)phenol, 2-(4-hydroxyphenol) ethanol, 2-carbethoxyphenol, 4-chloro-methylphenol and mixtures thereof. It is especially preferred that the phenols used to prepare the Mannich polyols of the present invention be unsubstituted phenol or a phenol havin
Molina Nelson F.
Moore Stanley E.
Cooney Jr. John M.
The Dow Chemical Company
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