WO2010009189A1

WO2010009189A1 - Hydrogenation of aromatic polyols

Info

Publication number: WO2010009189A1
Application number: PCT/US2009/050625
Authority: WO
Inventors: Adrian Birch; Phillip Athey; Zenon Lysenko; Alan Schrock
Original assignee: Dow Global Technologies Inc.
Priority date: 2008-07-16
Filing date: 2009-07-15
Publication date: 2010-01-21

Abstract

The present invention describes a composition comprising at least one aromatic amine alkoxylate and at least one corresponding cycloaliphatic amine alkoxylate. The present invention also describes a process comprising the steps of alkoxylating at least one aromatic amine initiator with at least one alkene oxide to form at least one aromatic amine alkoxylate, and subsequently hydrogenating the at least one aromatic amine alkoxylate to form a composition comprising aromatic amine alkoxylates and corresponding cycloaliphatic amine alkoxylates.

Description

HYDROGENATION OF AROMATIC POLYOLS

FIELD OF INVENTION

The invention relates to a composition comprising aromatic amine alkoxylates and corresponding cycloaliphatic amine alkoxylates, the process for making them, and polyurethane products made therefrom.

BACKGROUND OF THE INVENTION

Polyols are compounds that have at least one group containing an active hydrogen atom capable of undergoing reaction with an isocyanate. Preferred among such compounds are materials having at least two hydroxyls, primary or secondary, or at least two amines, primary or secondary, carboxylic acid, or thiol groups per molecule. Compounds having at least two hydroxyl groups or at least two amine groups per molecule are especially preferred due to their desirable reactivity with polyisocyanates.

Difficulty exists in attempting to create polyols from certain aromatic amine initiators. When some aromatic amines such as aromatic diamines, especially ortho diamines such as o-toluenediamine (o-TDA) and o-phenyldiamine (o-PDA), are hydrogenated, hydrogenation catalyst poisoning has been reported in the prior art. This poisoning occurs because at least one amine on the aromatic amine attacks the hydrogenation catalyst. Due to the relative expense of the hydrogenation catalyst and the regeneration, if possible, of such, processes for making cycloaliphatic polyols from aromatic amine initiators are not desirable. U.S. Patent No. 6,429,338 (Burdeniuc, et al.) describes the problem generally and attempts to provide a solution by using a metal alkali in a solvent process to control the interaction between aromatic diamines and the hydrogenation catalyst during hydrogenation and before polyol functional group addition.

Another problem that is reported in prior art involves the use of an additional purification step for processing such compositions. In between hydrogenation and alkoxylation steps, a purification step is required to not only remove the hydrogenated product from the non-hydrogenated starting and intermediate materials (partially and fully aromatic initiator) but also to remove the hydrogenation catalyst. Removal of the hydrogenation catalyst is required as it may be poisoned by reaction with alkene oxides. U.S. Patent No. 6,437,194 (Inoue, et al.) describes distillation steps for recovering hydrogenation products of phenolic adducts before further reaction.

SUMMARY OF THE INVENTION

An embodiment of the invention includes a composition comprising at least one aromatic amine alkoxylate and at least one corresponding cycloaliphatic amine alkoxylate. In some embodiments, the ratio of the at least one corresponding cycloaliphatic amine alkoxylate to the at least one aromatic amine alkoxylates is in a range of about 1:99 to about 99:1. In other embodiments, the at least one corresponding cycloaliphatic amine alkoxylates comprises at least 60% of the mixture. In some embodiments, the at least one aromatic amine alkoxylate is an adduct of at least one aromatic amine initiator and at least one alkene oxide. In some such embodiments, the at least one aromatic amine initiator is selected from the group comprising toluenediamine (TDA), methylene diphenyl diamine (MDA), aniline, phenylenediamine (PDA), xylenediamine (XDA), naphthalene diamine, polymeric methylenedianiline, tetramethyl xylene diamine, and mixtures thereof. In specific embodiments, the at least one aromatic amine initiator is an ortho aromatic diamine. In other specific embodiments, the at least one alkene oxide is selected from the group comprising ethylene oxide, propylene oxide, butylene oxide, and mixtures thereof. In some embodiments, the composition further comprises at least one non-aromatic alkoxylated polyol. In other embodiments, the composition further comprises at least one non-aromatic polyol. In other embodiments, the composition further comprises a cycloaliphatic amine.

An embodiment of the invention includes a composition comprising the hydrogenation product of an adduct of at least one aromatic amine initiator and at least one alkene oxide. In some embodiments, the at least one aromatic amine initiator is selected from the group comprising toluenediamine (TDA), methylene diphenyl diamine (MDA), aniline, phenylenediamine (PDA), xylenediamine (XDA), naphthalene diamine, polymeric methylenedianiline, tetramethyl xylene diamine, and mixtures thereof. In specific embodiments, the at least one aromatic amine initiator is an ortho aromatic diamine. In some embodiments, the adduct is hydrogenated to at least 60% saturation. In some embodiments, the at least one alkene oxide is selected from the group comprising ethylene oxide, propylene oxide, butylene oxide, and mixtures thereof.

An embodiment of the invention includes a process of alkoxylating at least one aromatic amine initiator with at least one alkene oxide to form at least one aromatic amine alkoxylate, and then subsequently hydrogenating the at least one aromatic amine alkoxylate to form a composition comprising aromatic amine alkoxylates and corresponding cycloaliphatic amine alkoxylates. In some embodiments, the at least one aromatic amine alkoxylate is hydrogenated to at least 60% saturation. In some embodiments, the at least one aromatic amine initiator is selected from the group comprising toluenediamine (TDA), methylene diphenyl diamine (MDA), aniline, phenylenediamine (PDA), xylenediamine (XDA), naphthalene diamine, polymeric methylenedianiline, tetramethyl xylene diamine, and mixtures thereof. In specific embodiments, the at least one aromatic amine initiator is an ortho aromatic diamine. In some embodiments, the at least one alkene oxide is selected from the group comprising ethylene oxide, propylene oxide, butylene oxide, and mixtures thereof. In some embodiments, at least one non-aromatic amine is alkoxylated to form at least one non-aromatic amine alkoxylate polyol during the alkoxylating step.

An embodiment of the invention includes a process of forming a polyol composition comprising blending at least one aromatic amine alkoxylate with at least one corresponding cycloaliphatic amine alkoxylate.

An embodiment of the invention includes an article comprising a polyurethane adduct of at least one isocyanate and a polyol composition comprising at least one aromatic amine alkoxylate and at least one corresponding cycloaliphatic amine alkoxylate.

An embodiment of the invention includes a process for preparing a rigid foam of forming a reactive mixture containing at least a composition comprising at least one aromatic amine alkoxylate and at least one corresponding cycloaliphatic amine alkoxylate; at least one hydrocarbon, hydrofluorocarbon, hydrochlorofluorocarbon, fluorocarbon, dialkyl ether or fluorine-substituted dialkyl ether physical blowing agent; and at least one polyisocyanate; and then subjecting the reactive mixture to conditions such that the reactive mixture expands and cures to form a rigid polyurethane foam. In some embodiments, the reactive mixture further contains water.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The term "correspond" means to be like, as in the arrangement or relation of parts; to compare closely.

Embodiments of the invention relate to polyol compositions comprised of aromatic amine alkoxylates and their corresponding cycloaliphatic amine alkoxylates. These compositions, when combined with isocyanates under reactive conditions well known in the art, form polyurethane foam products. Depending on the processing of the initiator material - an aromatic amine - the resultant polyol or mixture of polyols can provide a desired level of flexibility or rigidity when used as part of a polyurethane foam system.

Embodiments of the invention relate to the process of creating polyol compositions comprising aromatic amine alkoxylates and their corresponding cycloaliphatic amine alkoxylates via alkoxylating at least one aromatic amine initiator and then hydrogenating the alkoxylated aromatic amine. By using a process where alkoxylation of the aromatic amine initiator occurs before hydrogenation, it has been discovered that the prior art problems of hydrogenation catalyst poisoning are avoided.

Embodiments of the inventive process for making the polyol compositions have the benefit of where the steps and problems related to hydrogenation catalyst poisoning and additional distillation steps are avoided. Although not wanting to be bound by theory, it is believed that by alkoxylating at least one of the amino groups bonded to the aromatic nucleus before hydrogenation, especially diamines, and especially diamines in the ortho position relative to one other, prevents poisoning of the hydrogenation catalyst by stericly hindering the amino groups. The amino groups are stericly hindered from attacking the catalyst by the polyalkene oxide group formed on at least one of the amine groups. Additionally, the general reactivity of hydrogen that is part of the amino group that has the polyalkene oxide group attached (i.e., a secondary amine) is significantly reduced. Therefore, it is believed the hydrogenation step where the amines, especially diamines, and especially o/t/zo-diamines, are hindered by association with a metal solution ion as stated in the prior art should no longer be required. Additionally, the inventive process does not require a refining step to separate out hydrogenation catalyst before alkoxylation or purification of alkoxylated from non-alkoxylated adducts since hydrogenation is the final step and not an intermediary step.

With the ability to control the level and type of alkoxylation and the subsequent level of hydrogenation, embodiment compositions comprising aromatic amine alkoxylates and corresponding cycloaliphatic amine alkoxylates polyols with differing types and amounts of alkoxylation and levels of hydrogenation may be produced.

Embodiment compositions may also include alkoxylated and hydrogenated derivatives of other non-amine and non-aromatic amine initiators. In some embodiment processes, these initiators are alkoxylated and hydrogenated in the same process which forms the inventive polyol composition comprising aromatic amine alkoxylates and corresponding cycloaliphatic amine alkoxylates.

The inventive polyol compositions, especially those compositions formed from ort/zo-diamine aromatic intiators, are useful in formulations for producing rigid polyurethane foam with both demolding and insulation performance equivalent to or better than foams based upon similar aromatic amine polyol counterparts (i.e., similar molecular formula without the hydrogenation process). Additionally, the inventive polyol compositions possess higher reactivity than the similar aromatic amine polyols which may allow for a reduction in catalyst usage. As well, it is known that cycloaliphatic amines have better resistance to light-based degradation than similar aromatic amines. Therefore, products made from the inventive polyol compositions such as polyurethane foams will have improved structural longevity and color control over those products using similar aromatic amine polyol compositions. This makes the inventive polyol composition favorable for use in elastomers, paint additives, and epoxy resin formulations.

The aromatic amine initiator used in forming the inventive polyol compositions has at least one amino group bonded to at least one aromatic group. Examples of the aromatic amine initiators include simple aromatic amines, aromatic diamines, and polynuclear amines initiators. Examples of simple aromatic amine initiators include, but are not limited to, aniline, isomers of toluene amines, phenol amines, phenyldimethyl amines. Examples of aromatic diamine initiators include, but are not limited to, toluenediamine (TDA), phenylenediamine (PDA), xylene diamine (XDA), diethyltoluene diamine, and tetramethylxylylene diamine (TMXDA). Preferred aromatic amine initiators include ortho isomers of aromatic diamine initiators such as ort/zo-toruenediamine (oTDA) and ort/zo-phenyldiamine (oPDA). Aromatic amine initiator may have one or more aromatic nuclei, meaning the initiator may be mononuclear or polynuclear. Additionally, the aromatic nuclei may also be linked by sharing common bonds or via alkyl links, such as by a methyl or ethyl link. Non-limiting examples of polynuclear initiators include napthadiamine (NDA), 4,4'- and 2,4' -methylene diphenyl diamine (MDA), and polymeric MDA (PMDA).

The aromatic amine initiator may have at least one amino group bonded, either directly to or indirectly via an ether or alkyl link, to an aromatic nucleus. A non- limiting example of an indirect link via an alkyl group includes phenylethylamine. The aromatic amine initiator may have a combination on the same aromatic nucleus at least one directly bonded amino group and at least one indirectly bonded amino group.

Each of the bonded amino groups, independently, may be a primary, secondary, or tertiary amine; however, at least one of the bonded amino groups must have at least one liable hydrogen available for alkoxylation.

The aromatic amine initiator may have substitutes other than hydrogen on the aromatic nucleus. Examples of such substitutes include alkyl units such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, or tert-butyl groups. Other non-alkyl groups include, but are not limited to, hydroxyl, halogens, aromatics and alkyl-linked aromatics, organic acids, and nitro groups. The aromatic compound with at least one associated amine group can also have other aromatic ring substitutes linked directly or via an alkyl group, such as a methyl or ethyl group. It is preferred that other substitutes on the aromatic ring group do not chemically or stericly hinder all of the amines so that all the free hydrogens on all the associated amine groups are non- reactive.

In some embodiments, the aromatic amine initiators may be highly purified materials; however, commercially available feed grades may contain other amine compounds, including isomers of the desired initiator material, other aromatic amines, or other non-aromatic amines, and mixtures thereof.

Alkene oxides useful for creation of the inventive polyol composition include such oxides as ethylene oxide, propylene oxide, isomers of butylene oxide, and mixtures of two or more different types of oxides. The level and amount of alkoxylation substitution onto each of the bonded amine groups depends on many factors, including reaction temperature, type and concentration of alkoxylates, type and concentration of aromatic amine initiators, number of bonded amine groups, and steric hindrance of potential liable hydrogen reaction sites.

If two liable hydrogens are available for alkoxylation, as would be with a primary amine, in some embodiments a single hydrogen atom on the amino group may be substituted with an alkene oxide and form an oxypolyalkylene group. In other embodiments, both hydrogens, independently, may be substituted each with an alkene oxide to form individual oxypolyalkylene structures. In such embodiments, the respective oxypolyalkene oxide structures may be comprised of different materials and overall lengths. If one liable hydrogen is available, as would be with a secondary amine, in some embodiments the single hydrogen atom may be substituted with an alkene oxide to form an oxypolyalkylene oxide group.

The alkoxylation reaction step is performed mixing at least one alkylene oxide and at least one aromatic amine initiator together and subjecting the mixture to appropriate reaction conditions to form the aromatic amine alkoxylate adduct. It is known to one of ordinary skill in the art the means and methods for safely and efficiently performing the alkoxylation reactions with initiator aromatic amines and alkylene oxides.

For the alkoxylation reaction, a catalyst may be used, particularly if more than one mole of alkylene oxide(s) is to be added per equivalent of liable amino hydrogens on the aromatic amine initiator. Suitable alkoxylation catalysts include strong bases such as alkali metal hydroxides (sodium hydroxide, potassium hydroxide, cesium hydroxide, for example), boron triflouride, as well as the so-called double metal cyanide catalysts (of which zinc hexacyanocobaltate and quaternary phosphazenium complexes are most notable). In some embodiments, the reaction can be performed in two or more stages, in which no catalyst is used in the first stage, and from 1 to 3 moles of alkylene oxide are added per mole of aromatic amine, followed by one or more subsequent stages in which additional alkylene oxide is added in the presence of a catalyst. After the reaction is completed, the catalyst may be deactivated or removed; however, this is not required. Alkali metal hydroxide catalysts may be removed, left in the product, or neutralized with an acid and the residues left in the product. Residues of double metal cyanide catalysts may be left in the product but also may be removed. The reaction substitution may occur with at least one primary or secondary amine associated with the aromatic ring.

The ratios of alkylene oxide and aromatic amine initiator are selected such that the resulting adduct has a hydroxyl number of from about 200 to about 800. In some embodiments, a portion of the amino hydrogens on the aromatic amine often do not become alkoxylated under typical alkoxylation conditions, which would lead to the formation of an adduct having, on average, both hydroxyl groups and primary or secondary amine groups, or both. More specifically, in such embodiments, it is believed that the adduct may contain a significant proportion of molecules that contain one primary amino group and one alkoxylated tertiary amino group. It is to be understood by one skilled in the art that the resultant aromatic amine alkoxylate polyols vary in both level of polyalkoxylation (length of polyoxide chain) and frequency of alkoxylation (number of liable hydrogens remaining on the amino groups of the aromatic amine alkoxylates). The level of saturation (hydrogenation) of the inventive polyol composition depends on a variety of factors, such as the amount of excess hydrogen used to saturate the unsaturated portions of the aromatic amine alkoxylates, the catalyst(s) used in the hydrogenation, and processing conditions. The level of saturation of the inventive polyol composition is determined by comparing the amount of fully saturated corresponding cycloaliphatic amine alkoxylates produced from hydrogenation versus the amount of the aromatic amine alkoxylates supplied. It is understood by those in the art that some of the aromatic amine alkoxylates will not be fully saturated during hydrogenation.

In some embodiments, the mixture will by hydrogenated to a level where it is over 60% saturated. This means that over than 60% of the aromatic amine alkoxylates before saturation will be fully converted to the corresponding cycloaliphatic amine alkoxylates. In some other preferred embodiments, the mixture will be hydrogenated to a level of over 70% saturated. In some other more preferred embodiments, the mixture will be hydrogenated to a level of over 80% saturated. In some other most preferred embodiments, the mixture will be hydrogenated to a level of over 90% saturated.

In some embodiments, the ratio of corresponding cycloaliphatic amine alkoxylates to aromatic amine alkoxylates in the inventive polyol composition is in a range of about 1:99 to about 99:1. In some other embodiments, the ratio is in a range of about 10:90 to about 90:10. In some other preferred embodiments, the ratio is in a range of about 20:80 to about 80:20. In some other more preferred embodiments, the ratio is in a range of about 30:70 to about 70:30. In some other most preferred embodiments, the ratio is in a range of about 40:60 to about 60:40.

The inventive polyol composition will include a portion of material that can be described as "partially saturated" corresponding cycloaliphatic amine alkoxylates, where the aromatic group of the aromatic amine alkoxylates is partially but not completely hydrogenated, leaving one or more unsaturated bonds in the structure.

Catalysts may be used for the hydrogenation step to assist formation of the cycloaliphatic amine alkoxylates and analogous aromatic amine alkoxylates polyol composition from the initiator aromatic amine and alkene oxide adduct. For example, U.S. Patent No. 3,336,241 (Shokal) teaches hydrogenating aromatic compound with a catalyst such as rhodium or ruthenium metal, supported on an inert carrier, such as carbon, at temperatures of 30 ⁰C to 100 ⁰C. Another example includes U.S. Patent No. 5,530,147 (Wettling, et al.), where a ruthenium compound is mixed with an aromatic alkoxylate and then hydrogenated at pressures of 200 bar to 310 bar and temperatures of 40 ⁰C to 70 ⁰C. Other example techniques for hydrogenation are taught in U.S. Patent Nos. 4,045,508 (Cupples, et al.); 4,013,736 (Woo); 3,997,622 (Isa, et al.); 3,997,621 (Brennan); and 3,152,998 (Moss). The example techniques for hydrogenation may be utilized with a number of metal catalysts suitable for hydrogenation, such as nickel, platinum, palladium, copper, and Rainey nickel supported on a variety of porous materials, such as alumina, charcoal, or kieselguhr.

In some embodiments, a cycloaliphatic amine is included in the inventive polyol compositions. In such embodiments, where some of the aromatic amine initiator does not alkoxylate but does hydrogenate, part of the inventive composition further comprises a hydrogenated derivative of the aromatic amine initiator. In such embodiments, it is expected that the levels of saturation of such hydrogenated but not alkoxylated aromatic amine initiators would be similar to the proportions found between the aromatic amine alkoxylates and the corresponding cycloaliphatic amine alkoxylates.

In some embodiments, an additional step of further alkoxylation of the inventive polyol compositions may be performed after hydrogenation to add additional polyol structures to the hydrogenated adduct. In some embodiments, a different alkene oxide or mixture thereof may be used than the mixture used in the prior alkoxylation.

In addition, other initiators may be added to the inventive polyol compositions either before the alkoxylation step or the hydrogenation step to enhance desired overall polyol mixture characteristics, such as reducing viscosity or improving hydroxyl number. In some embodiments, another initiator may be added to the composition before alkoxylation and be alkoxylated and then hydrogenated in situ with the aromatic amine initiator to form part of the inventive polyol composition. This in situ reaction avoids additional process and refining steps and permits intimate blending of the polyols. In some embodiments, the inventive polyol compositions further comprise at least one non-aromatic alkoxylated polyol. In some other embodiments, the inventive polyol compositions further comprise at least one non- aromatic polyol. Examples of such materials may include an amine polyol or a glycerine polyol.

A preferred average hydroxyl functionality for the inventive polyol compositions is from about 3.8 to about 6 hydroxyl groups per molecule. A more preferred average hydroxyl functionality for a polyol mixture is from about 3.8 to about 5 hydroxyl groups/molecule. A preferred average hydroxyl equivalent weight for a polyol mixture is from about 110 to about 130.

Suitable polyols that can be used in conjunction with the inventive polyol compositions include polyether polyols, which are conveniently made by polymerizing an alkylene oxide onto an initiator compound (or mixture of initiator compounds) that has multiple active hydrogen atoms. The initiator compound(s) may include alkylene glycols (e.g., ethylene glycol, propylene glycol, 1,4-butane diol, 1,6- hexanediol and the like), glycol ethers (such as diethylene glycol, Methylene glycol, dipropylene glycol, tripropylene glycol and the like), glycerine, trimethylolpropane, pentaerythritol, sorbitol, sucrose, glucose, fructose or other sugars, and the like. A portion of the initiator compound may be one containing primary and/or secondary amino groups, such as ethylene diamine, diethanolamine, monoethanolamine, piperazine, aminoethylpiperazine, diisopropanolamine, monoisopropanolamine, methanolamine, dimethanolamine and the like. Amine-initiated polyols of these types tend to be somewhat autocatalytic. The alkylene oxide used to make the additional polyol(s) are as described before with respect to the amine-initiated polyol of the invention. The alkylene oxide of choice is propylene oxide, or a mixture of propylene oxide and ethylene oxide.

Polyester polyols may also be used as an additional polyol, but are generally less preferred as they tend to have lower functionalities. The polyester polyols include reaction products of polyols, preferably diols, with polycarboxylic acids or their anhydrides, preferably dicarboxylic acids or dicarboxylic acid anhydrides. The polycarboxylic acids or anhydrides may be aliphatic, cycloaliphatic, aromatic and/or heterocyclic and may be substituted, such as with halogen atoms. The polycarboxylic acids may be unsaturated. Examples of these polycarboxylic acids include succinic acid, adipic acid, terephthalic acid, isophthalic acid, trimellitic anhydride, phthalic anhydride, maleic acid, maleic acid anhydride and fumaric acid. The polyols used in making the polyester polyols include ethylene glycol, 1,2- and 1,3-propylene glycol, 1,4- and 2,3-butane diol, 1,6-hexane diol, 1,8-octane diol, neopentyl glycol, cyclohexane dimethanol, 2-methyl-l,3-propane diol, glycerine, trimethylol propane, 1,2,6-hexane triol, 1,2,4-butane triol, trimethylol ethane, pentaerythritol, quinitol, mannitol, sorbitol, methyl glycoside, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, dibutylene glycol and the like.

In a preferred embodiment, inventive polyol compositions is used as a mixture with at least one other polyether polyol that has an average functionality of from 4.5 to 7 hydroxyl groups per molecule and a hydroxyl equivalent weight of 100 to 175. The other polyether polyol may be, for example, a sorbitol- or sucrose/glycerine- initiated polyether. The inventive polyol compositions may constitute from 10 to 70% of the weight of the mixture in this case. Examples of suitable sorbitol- or sucrose/glycerine-initiated polyethers that can be used include, but are not limited to, VORANOL® 360, VORANOL ® RN411, VORANOL ® RN490, VORANOL ® 370, VORANOL ® 446, VORANOL ® 520, VORANOL ® 550 and VORANOL ® 482 polyether polyols (The Dow Chemical Company; Midland, Mi).

In another preferred embodiment, inventive polyol compositions is used in a polyol mixture that also contains at least one other polyether polyol that has an average functionality of from 4.5 to 7 hydroxyl groups per molecule and a hydroxyl equivalent weight of 100 to 175, and which is not amine-initiated, and at least one other amine-initiated polyol having an average functionality of from 2.0 to 4.0 (preferably 3.0 to 4.0) and a hydroxyl equivalent weight of from 100 to 225. The other amine-initiated polyol may be initiated with, for example, ammonia, ethylene diamine, diethanolamine, monoethanolamine, piperazine, aminoethylpiperazine, diisopropanolamine, monoisopropanolamine, methanolamine, dimethanolamine and the like. Ethylene diamine-initiated polyols are preferred in this case. The polyol mixture may contain from 5 to 50% by weight of the amine-initiated polyol of the invention; from 20 to 70% by weight of the non-amine-initiated polyol and from 2 to 20% by weight of the other amine-initiated polyol. The polyol mixture may contain up to 15% by weight of still another polyol, which is not amine-initiated and which has a hydroxyl functionality of 2.0 to 3.0 and a hydroxyl equivalent weight of from 90 to 500, preferably from 200 to 500. Specific examples of polyol mixtures as just described include a mixture of from 5-50% by weight of the amine-initiated polyol of the invention, from 20 to 70% of a sorbitol or sucrose/glycerine initiated polyether polyol having an average functionality of from 4.5 to 7 hydroxyl groups per molecule and a hydroxyl equivalent weight of 100 to 175, from 2 to 20% by weight of an ethylenediamine-initiated polyol having an equivalent weight of from 100 to 225, and from 0 to 15% by weight of a non-amine-initiated polyol having a functionality of from 2.0 to 3.0 and hydroxyl equivalent weight of from 200 to 500.

The polyurethane-forming composition contains at least one organic polyisocyanate. The organic polyisocyanate or mixture thereof advantageously contains an average of at least 2.5 isocyanate groups per molecule. A preferred isocyanate functionality is from about 2.5 to about 3.6 or from about 2.6 to about 3.3 isocyanate groups/molecule. The polyisocyanate or mixture thereof advantageously has an isocyanate equivalent weight of from about 130 to 200. This is preferably from 130 to 185 and more preferably from 130 to 170. These functionality and equivalent weight values need not apply with respect to any single polyisocyanate in a mixture, provided that the mixture as a whole meets these values.

Suitable polyisocyanates include aromatic, aliphatic and cycloaliphatic polyisocyanates. Aromatic polyisocyanates are generally preferred. Exemplary polyisocyanates include, for example, m-phenylene diisocyanate, 2,4- and/or 2,6- toluene diisocyanate (TDI), the various isomers of diphenylmethanediisocyanate (MDI), hexamethylene-l,6-diisocyanate, tetramethylene-l,4-diisocyanate, cyclohexane-l,4-diisocyanate, hexahydrotoluene diisocyanate, hydrogenated MDI (H12 MDI), naphthylene-l,5-diisocyanate, methoxyphenyl-2,4-diisocyanate, 4,4'- biphenylene diisocyanate, 3,3'-dimethyoxy-4,4'-biphenyl diisocyanate, 3,3'- dimethyldiphenylmethane-4,4' -diisocyanate, 4,4' ,4"-triphenylmethane diisocyanate, polymethylene polyphenylisocyanates, hydrogenated polymethylene polyphenyl polyisocyanates, toluene-2,4,6-triisocyanate and 4,4'-dimethyldiphenylmethane- 2,2',5,5'-tetraisocyanate. Preferred polyisocyanates are the so-called polymeric MDI products, which are a mixture of polymethylene polyphenylene polyisocyanates in monomeric MDI. Especially suitable polymeric MDI products have a free MDI content of from 5 to 50% by weight, more preferably 10 to 40% by weight. Such polymeric MDI products are available from The Dow Chemical Company under the trade names PAPI® and Voranate®.

An especially preferred polyisocyanate is a polymeric MDI product having an average isocyanate functionality of from 2.6 to 3.3 isocyanate groups/molecule and an isocyanate equivalent weight of from 130 to 170. Suitable commercially available products of that type include PAPI® 27, VORANATE™ M229, VORANATE ® 220, VORANATE ® 290, VORANATE ® M595 and VORANATE ® M600 (available from The Dow Chemical Co.; Midland, Mi).

Isocyanate-terminated prepolymers and quasi-prepolymers (mixtures of prepolymers with unreacted polyisocyanate compounds) can also be used. These are prepared by reacting a stoichiometric excess of an organic polyisocyanate with a polyol, such as the polyols described above. Suitable methods for preparing these prepolymers are well known. Such a prepolymer or quasi-prepolymer preferably has an isocyanate functionality of from 2.5 to 3.6 and an isocyanate equivalent weight of from 130 to 200.

The polyisocyanate is used in an amount sufficient to provide an isocyanate index of from 90 to 200. Isocyanate index is calculated as the number of reactive isocyanate groups provided by the polyisocyanate component divided by the number of isocyanate -reactive groups in the polyurethane-forming composition (including those contained by isocyanate-reactive blowing agents such as water) and multiplying by 100. Water is considered to have two isocyanate-reactive groups per molecule for purposes of calculating isocyanate index. A preferred isocyanate index is from 100 to 150.

The polyisocyanate is used in an amount sufficient to provide an isocyanate index of from 80 to 600. Isocyanate index is calculated as the number of reactive isocyanate groups provided by the polyisocyanate component divided by the number of isocyanate-reactive groups in the polyurethane-forming composition (including those contained by isocyanate-reactive blowing agents such as water) and multiplying by 100. Water is considered to have two isocyanate-reactive groups per molecule for purposes of calculating isocyanate index. A preferred isocyanate index is from 90 to 400 and a more preferred isocyanate index is from 100 to 150.

The blowing agent used in the polyurethane-forming composition includes at least one physical blowing agent which is a hydrocarbon, hydrofluorocarbon, hydrochlorofluorocarbon, fluorocarbon, dialkyl ether or fluorine-substituted dialkyl ethers, or a mixture of two or more thereof. Blowing agents of these types include propane, isopentane, n-pentane, n-butane, isobutene, isobutene, cyclopentane, methylcyclopentane, methylcyclohexane, cyclohexane, dimethyl ether, 1,1-dichloro- 1-fluoroethane (HCFC-UIb), chlorodifluoromethane (HCFC-22), l-chloro-1,1- difluoroethane (HCFC-142b), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1,3,3- pentafluorobutane (HFC-365mfc), 1,1-difluoroethane (HFC-152a), 1,1,1,2,3,3,3- heptafluoropropane (HFC-227ea) and 1,1,1,3,3-pentafluoropropane (HFC-245fa). The hydrocarbon and hydrofluorocarbon blowing agents are preferred. It is generally preferred to further include water in the formulation, in addition to the physical blowing agent.

Blowing agent(s) are preferably used in an amount sufficient such that the formulation cures to form a foam having a molded density of from 16 to 160 kg/m3, preferably from 16 to 64 kg/m3 and especially from 20 to 48 kg/m3. To achieve these densities, the hydrocarbon or hydrofluorocarbon blowing agent conveniently is used in an amount ranging from about 10 to about 40, preferably from about 12 to about 35, parts by weight per 100 parts by weight polyol(s). Water reacts with isocyanate groups to produce carbon dioxide, which acts as an expanding gas. Water is suitably used in an amount within the range of 0.5 to 3.5, preferably from 1.5 to 3.0 parts by weight per 100 parts by weight of polyol(s).

The polyurethane-forming composition typically will include at least one catalyst for the reaction of the polyol(s) and/or water with the polyisocyanate. Suitable urethane-forming catalysts include those described by U.S. Patent No. 4,390,645 and in PCT Published Application No. WO 02/079340. Representative catalysts include tertiary amine and phosphine compounds, chelates of various metals, acidic metal salts of strong acids; strong bases, alcoholates and phenolates of various metals, salts of organic acids with a variety of metals, organometallic derivatives of tetravalent tin, trivalent and pentavalent As, Sb and Bi and metal carbonyls of iron and cobalt.

Tertiary amine catalysts are generally preferred. Among the tertiary amine catalysts are dimethylbenzylamine (such as Desmorapid® DB from Rhine Chemie), 1,8-diaza (5,4,0)undecane-7 (such as Polycat® SA-I from Air Products), pentamethyldiethylenetriamine (such as Polycat® 5 from Air Products), dimethylcyclohexylamine (such as Polycat® 8 from Air Products), Methylene diamine (such as Dabco® 33LV from Air Products), dimethyl ethyl amine, n-ethyl morpholine, N-alkyl dimethylamine compounds such as N-ethyl N,N-dimethyl amine and N-cetyl N,N-dimethylamine, N-alkyl morpholine compounds such as N-ethyl morpholine and N-coco morpholine, and the like. Other tertiary amine catalysts that are useful include those sold by Air Products under the trade names DABCO® NE1060, DABCO ® NE1070, DABCO ® NE500, DABCO ® TMR-2, DABCO ® TMR 30, POLYCAT® 1058, POLYCAT ® 11, POLYCAT 15, POLYCAT ® 33 POLYCAT ® 41 and DABCO ® MD45, and those sold by Huntsman under the trade names ZR 50 and ZR 70. In addition, certain amine-initiated polyols can be used herein as catalyst materials, including those described in PCT Published Application No. WO 01/58976 A. Mixtures of two or more of the foregoing may be used.

The catalyst is used in catalytically sufficient amounts. For the preferred tertiary amine catalysts, a suitable amount of the catalysts is from about 1 to about 10 parts, especially from about 2 to about 6 parts, of tertiary amine catalyst(s) per 100 parts by weight of the polyol(s). In preferred embodiments, the amount of catalyst is at least 4 parts per 100 parts by weight of the polyol(s).

Typically, 0.2 to 5 parts of the surfactant per 100 parts by total weight active hydrogen-containing compound(s) present are generally sufficient for this purpose. A preferred amount of surfactant per 100 parts total weight active hydrogen-containing compounds is a range of about 1 to 3 parts. The polyurethane-forming composition also preferably contains at least one surfactant, which helps to stabilize the cells of the composition as gas evolves to form bubbles and expand the foam. Organosilicone surfactants are generally preferred types of surfactants. A wide variety of these organosilicone surfactants are commercially available, including those sold under the TEGOSTAB® name (such as TEGOSTAB® B 8462, B 8427, B 8433 and B 8404 surfactants) (Evonik Goldschmidt GmbH; Essen, Germany), those sold under the NIAX® name (such as NIAX® L6900 and L6988 surfactants) (Momentive Performance Materials; Friendly, WV), as well those sold under the DABCO® name (such as DABCO® DC-193, DC- 198, DC-5000, DC-5043 and DC-5098 surfactants) (Air Products and Chemicals, Allentown, Penn.). Typically, 0.2 to 5 parts of the surfactant per 100 parts by total weight active hydrogen-containing compound(s) present are generally sufficient for this purpose. A preferred amount of surfactant per 100 parts total weight active hydrogen-containing compounds is a range of about 1 to 3 parts.

Examples of suitable surfactants include alkali metal and amine salts of fatty acids, such as sodium oleate, sodium stearate sodium ricinolates, diethanolamine oleate, diethanolamine stearate, diethanolamine ricinoleate, and the like: alkali metal and amine salts of sulfonic acids such as dodecylbenzenesulfonic acid and dinaphthylmethanedisulfonic acid; ricinoleic acid; siloxane-oxalkylene polymers or copolymers and other organopolysiloxanes; oxethylated alkylphenols (such as TERGITOL™ NP-9 nonionic surfactants and TRITON™ X-100 surfactants, available from The Dow Chemical Company); oxyethylated fatty alcohols such as TERGITOL™ 15-S-9 nonionic surfactants (The Dow Chemical Company); paraffin oils; castor oil; ricinoleic acid esters; turkey red oil; peanut oil; paraffins; fatty alcohols; dimethyl polysiloxanes and oligomeric acrylates with polyoxyalkylene and fluoroalkane side groups.

In addition to the foregoing ingredients, the polyurethane-forming composition may include various auxiliary components, such as fillers, colorants, odor masks, flame retardants, biocides, antioxidants, UV stabilizers, antistatic agents, viscosity modifiers, and the like. Examples of suitable flame retardants include phosphorus compounds, halogen-containing compounds and melamine.

Examples of fillers and pigments include calcium carbonate, titanium dioxide, iron oxide, chromium oxide, azo/diazo dyes, phthalocyanines, dioxazines, recycled rigid polyurethane foam and carbon black.

Examples of UV stabilizers include hydroxybenzotriazoles, zinc dibutyl thiocarbamate, 2,6-ditertiarybutyl catechol, hydroxybenzophenones, hindered amines and phosphites.

Except for fillers, the foregoing additives are generally used in small amounts, such as from 0.01 percent to 3 percent each by weight of the polyurethane formulation. Fillers may be used in quantities as high as 50% by weight of the polyurethane formulation.

A polyurethane-forming composition is prepared by bringing the various components together under conditions such that the polyol(s) and isocyanate(s) react, the blowing agent generates a gas, and the composition expands and cures. All components (or any sub-combination thereof) except the polyisocyanate can be pre- blended into a formulated polyol composition, if desired, which is then mixed with the polyisocyanate when the foam is to be prepared. The components may be preheated if desired, but this is usually not necessary, and the components can be brought together at about room temperature (~22°C) to conduct the reaction. It is usually not necessary to apply heat to the composition to drive the cure, but this may be done if desired, too.

In some embodiments, an article is comprised of a polyurethane adduct of at least one isocyanate and a polyol mixture of cycloaliphatic amine alkoxylates and their analogous aromatic amine alkoxylates. The inventive polyol mixture is useful in preparing both rigid and flexible polyurethane foam, depending on the level of alkoxylation polymerization. Rigid polyurethane foam is prepared from a polyurethane-forming composition that contains at least the inventive polyol mixture, at least one organic polyisocyanate, and at least one physical blowing agent. The inventive polyol mixture may be the only group of polyols in a polyurethane-forming composition; however, it is anticipated that in most cases the inventive polyol mixture will be further blended with at least one other polyol. In some embodiments, the other polyols in the polyol mixture will have been alkoxylated or hydrogentated, or both, along with the inventive polyol mixture as previously discussed.

The polyurethane-forming composition is prepared by bringing the various components together under conditions such that the polyol(s) and isocyanate(s) react, the blowing agent generates a gas, and the composition expands and cures. All components (or any sub-combination thereof) except the polyisocyanate, can be pre- blended into a formulated polyol composition, if desired, which is then mixed with the polyisocyanate when the foam is to be prepared. Alternatively, all components can be introduced individually to the mixing zone where the polyisocyanate and the saturated aromatic amine alkoxylate polyol compositions are contacted. It is also possible to prereact all or a portion of the active hydrogen- containing compound(s) with the polyisocyanate to form a prepolymer. The components may be preheated if desired, but this is usually not necessary, and the components can be brought together at about room temperature (~22°C) to conduct the reaction. It is usually not necessary to apply heat to the composition to drive the cure, but this may be done if desired.

In some embodiments, the rigid polyurethane foam application of the inventive polyol mixture is useful in so-called "pour-in-place" applications, in which the polyurethane-forming composition is dispensed into a cavity and foams within the cavity to fill it and provide structural or thermal insulative attributes, or both, to an assembly. The nomenclature "pour-in-place" refers to the fact that the foam is created at the location where it is needed, rather than being created in one step and later assembled into place in a separate manufacturing step. Pour-in-place processes are commonly used to make appliance products such as refrigerators, freezers, and coolers and similar products which have walls that contain thermal insulation foam. The presence of the inventive mixture in the polyurethane-forming composition tends to provide the formulation with good flow and short demold times, while at the same time producing a low k-factor foam. The presence of the inventive mixture also permits the use of less catalysts in molding applications and results in a composition that is more light stable due to the presence of fewer unsaturated aromatic groups in the product.

The walls of appliances such as refrigerators, freezers and coolers are most conveniently insulated in accordance with the invention by first assembling an outer shell and in interior liner together, such that a cavity is formed between the shell and liner. The cavity defines the space to be insulated as well as the dimensions and shape of the foam that is produced. Typically, the shell and liner are bonded together in some way, such as by welding, melt-bonding or through use of some adhesive (or some combination of these) prior to introduction of the foam formulation. In most cases, the shell and liner may be supported or held in the correct relative positions using a jig or other apparatus. One or more inlets to the cavity are provided, through which the foam formulation can be introduced. Usually, one or more outlets are provided to allow air in the cavity to escape as the cavity is filled with the foam formulation and the foam formulation expands.

The materials of construction of the shell and liner are not particularly critical, provided that they can withstand the conditions of the curing and expansion reactions of the foam formulation. In most cases, the materials of construction will be selected with regard to specific performance attributes that are desired in the final product. Metals such as steel are commonly used as the shell, particularly in larger appliances such as freezers or refrigerators. Plastics such as polycarbonates, polypropylene, polyethylene styrene-acrylonitrile resins, acrylonitrile-butadiene-styrene resins or high-impact polystyrene are used more often mailer appliances (such as coolers) or those in which low weight is important. The liner may be a metal, but is more typically a plastic as just described.

The foam formulation is then introduced into the cavity. The various components of the foam formulation are mixed together and the mixture introduced quickly into the cavity, where the components react and expand. It is common to pre- mix the polyol(s) together with the water and blowing agent (and often catalyst and/or surfactant as well) to produce a formulated polyol. The formulated polyol can be stored until it is time to prepare the foam, at which time it is mixed with the polyisocyanate and introduced into the cavity. It is usually not required to heat the components prior to introducing them into the cavity, nor it is usually required to heat the formulation within the cavity to drive the cure, although either or both of these steps may be taken if desired. The shell and liner may act as a heat sink in some cases, and remove heat from the reacting foam formulation. If necessary, the shell or liner, or both, can be heated somewhat (such as up to 50 ⁰C and more typically 35 - 40⁰C) to reduce this heat sink effect, or to drive the cure.

Enough of the foam formulation is introduced such that, after it has expanded, the resulting foam fills those portions of the cavity where foam is desired. Most typically, essentially the entire cavity is filled with foam. It is generally preferred to "overpack" the cavity slightly, by introducing more of the foam formulation than is minimally needed to fill the cavity, thereby increasing the foam density slightly. The overpacking provides benefits such as better dimensional stability of the foam, especially in the period following demold. Generally, the cavity is overpacked by from 4 to 20% by weight. The final foam density for most appliance applications is preferably in the range of from 28 to 40 kg/m3.

After the foam formulation has expanded and cured enough to be dimensionally stable, the resulting assembly can be "demolded" by removing it from the jig or other support that is used to maintain the shell and liner in their correct relative positions. Short demold times are important to the appliance industry, as shorter demold times allow more parts to be made per unit time.

Demold times can be evaluated as follows: A 28-liter "jumbo" Brett mold coated with release agent is conditioned to a temperature of 45 ⁰C. 896 g + 4 g of a foam formulation is injected into the mold in order to obtain a 32 kg/m³ density foam. After a period of 6 minutes, the foam is removed from the mold and the thickness of the foam is measured. After a further 24 hours, the foam thickness is re-measured. The difference between the thickness after 24 hours and the initial thickness is an indication of the post-demold expansion of the foam. The demold time is considered to be sufficiently long if the post-demold expansion is no more than 4 mm on this test. As mentioned, flow is another important attribute of the foam formulation. For purposes of this invention, flow is evaluated using a rectangular "Brett" mold, having dimensions of 200 cm x 20 cm x 5 cm (~6'6" x 8" x 2"). The polyurethane- forming composition is formed, and immediately injected into the Brett mold, which is oriented vertically (i.e., 200 cm direction oriented vertically) and preheated to 45 + 5 ⁰C. The composition is permitted to expand against its own weight and cure inside the mold. The amount of polyurethane-forming composition is selected such that the resulting foam just fills the mold. The density of the resulting foam is then measured and compared with the density of a free-rise foam made from the same formulation (by injecting the formulation into a plastic bag or open cardboard box where it can expand freely vertically and horizontally against atmospheric pressure). The ratio of the Brett mold foam density to the free rise density is considered to represent the "flow index" of the formulation. With this invention, flow index values are typically below 1.8, and are preferably from 1.2 to 1.5.

The polyurethane foam advantageously exhibits a low k-factor. The k-factor of a foam may depend on several variables, of which density is an important one. For many applications, a rigid polyurethane foam having a density of from 28.8 to 40 kg/m3 (1.8 to 2.5 pounds/cubic foot) exhibits a good combination of physical properties, dimensional stability, and cost. Foam in accordance with the invention, having a density within that range, preferably exhibits a 10⁰C k-factor of no greater than 22, preferably no greater than 20, and more preferably no greater than 19.5 mW/m-°K. Higher density foam may exhibit a somewhat higher k-factor.

All applications, publications, patents, test procedures, and other documents cited, including priority documents, are fully incorporated to the extent such disclosure is not inconsistent with this invention and for all jurisdictions in which such incorporation is permitted.

While the illustrative embodiments have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims to be limited to the examples and descriptions set forth but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents by those skilled in the art to which the invention pertains.

When numerical lower limits and numerical upper limits are listed here, ranges from any lower limit to any upper limit are contemplated, inclusive.

In the description, all numbers disclosed are approximate values, regardless whether the word "about" or "approximate" is used. Depending upon the context in which such values are described, and unless specifically stated otherwise, such values may vary by 1 percent, 2 percent, 5 percent, or, sometimes, 10 to 20 percent. Whenever a numerical range with a lower limit, RL and an upper limit, RU, is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=RL+k*(RU- RL), wherein k is a variable ranging from 0.01 to 1 with a 0.01 increment, that is, k is 0.01 or 0.02 to 0.99 or 1. Moreover, any numerical range defined by two R numbers as defined is also specifically disclosed.

Claims

We claim:

1. A composition comprising at least one aromatic amine alkoxylate and at least one corresponding cycloaliphatic amine alkoxylate.

2. The composition of claim 1, where ratio of the at least one corresponding cycloaliphatic amine alkoxylate to the at least one aromatic amine alkoxylates is in a range of about 1:99 to about 99:1.

3. The composition of claim 1, where the at least one corresponding cycloaliphatic amine alkoxylates comprises at least 60% of the mixture.

4. The composition of claim 1, where the at least one aromatic amine alkoxylate is an adduct of at least one aromatic amine initiator and at least one alkene oxide.

5. The composition of claim 4, where at least one aromatic amine initiator is selected from the group comprising toluenediamine (TDA), methylene diphenyl diamine (MDA), aniline, phenylenediamine (PDA), xylenediamine (XDA), naphthalene diamine, polymeric methylenedianiline, tetramethyl xylene diamine, and mixtures thereof.

6. The composition of claim 5, where the at least one aromatic amine initiator is an ortho aromatic diamine.

7. The composition of claim 5, where the at least one alkene oxide is selected from the group comprising ethylene oxide, propylene oxide, butylene oxide, and mixtures thereof.

8. The composition of claim 1, further comprising at least one non-aromatic alkoxylated polyol.

9. The composition of claim 1, further comprising at least one non-aromatic polyol.

10. The composition of claim 1, further comprising a cycloaliphatic amine.

11. A composition comprising the hydrogenation product of an adduct of at least one aromatic amine initiator and at least one alkene oxide.

12. The composition of claim 11, where the at least one aromatic amine initiator is selected from the group comprising toluenediamine (TDA), methylene diphenyl diamine (MDA), aniline, phenylenediamine (PDA), xylenediamine (XDA), naphthalene diamine, polymeric methylenedianiline, tetramethyl xylene diamine, and mixtures thereof.

13. The composition of claim 12, where the at least one aromatic amine initiator is an ortho aromatic diamine.

14. The composition of claim 11, where the adduct is hydrogenated to at least 60% saturation.

15. The composition of claim 11, where the at least one alkene oxide is selected from the group comprising ethylene oxide, propylene oxide, butylene oxide, and mixtures thereof.

16. A process for preparing a rigid foam comprising,

forming a reactive mixture containing at least a composition comprising at least one aromatic amine alkoxylate and at least one corresponding cycloaliphatic amine alkoxylate; at least one hydrocarbon, hydrofluorocarbon, hydrochlorofluorocarbon, fluorocarbon, dialkyl ether or fluorine- substituted dialkyl ether physical blowing agent; and at least one polyisocyanate; and subjecting the reactive mixture to conditions such that the reactive mixture expands and cures to form a rigid polyurethane foam.

17. The process of claim 16, where the reactive mixture further contains water.