LOW DENSITY CO2-BLOWN POLYURETHANE FOAMS AND A PROCESS OF PREPARING SAME

Abstract: Disclosed is a method of preparing a low density CO2-blown foam that has a high closed cell content. Foams prepared by the method of the present invention are useful in pour-in-place applications such as garage doors, doors, walk-in coolers, portable coolers, refrigerators, and water heaters, for example. Use of the method described herein reduces foam leakage from a mold during pour-in-place operations, and thus reduces waste and the cost associated with producing foam-filled articles made using a pour-in-place procedure.

Description: LOW DENSITY C0 2 -BLOWN POLYURETHANE FOAMS AND A PROCESS OF PREPARING SAME This invention relates to C0 2 -blown polyurethane foams. This invention particularly relates to low density C0 2 -blown polyureth.ane foams and a method of making same. Polyurethane and polyisocyanurate fo.ams (hereinafter foams) can be used in a variety of applications. As used herein, the term "foams" will be understood to include polyurethane-modified polyisocy-anurate foams and polyisocyanurate foams. Rigid polyurethane foams, for example, can provide support in applications where rigid support is desirable. Such applications include: construction materials for roofing, sheathing, building panels, pipe insulation, and vessel insulation; flotation; floral and craft foams; and lightweight structural parts for marine, aerospace and other industries, for example. Rigid foams can be prepared by various methods, including block-foam, double-band lamination, discontinuous panel, and pour-in-place processes. The double- band lamination, discontinuous panel, and pour-in-place processes can each be used to prepare a rigid foam in situ in a single step. A pour-in-place (PIP) process is a process wherein a polyurethane foam formulation is poured into an empty shell, mold or casing (hereinafter mold) and the foam fills the mold to form a foam-filled article. The PIP process and its useful applications are well known in the .art of preparing polyurethane foams (see, for example, Reaction Polymers: Gum, W. F., Riese, W., and Ulrich, H., Eds. Hanser: New York 1992; pg. 575). Articles made by the PIP method include, for example, garage doors, walk-in coolers, portable coolers, refrigerators, doors, and water heaters. The foams described herein include rigid foams, molded foams and slabstock foams. When used in a PIP process, a polyurethane foam formulation can escape or leak from a mold if foaming does not occur during, or soon after, pouring. Leakage from a mold can result in higher costs associated with production of a foam product, due to loss of product and increased maintenance costs. In current practice leakage is typically reduced by adding a low-boiling compound at ambient temperature into a foaming system to enhance pre-expansion of the foaming system, or frothing, of the foaming system at the start of the polyurethane reaction. This practice, however, normally requires modification of conventional equipment. Pre-expansion, as used herein, refers to an increase in the volume of a foaming system, that is a polyurethane- forming reaction mixture, prior to the start of the polyurethane reaction. Typically polyurethane foams utilize blowing agents, such as halogenated alkanes, to produce the cellular structure found in a polyurethane foam. C0 2 can be a useful blowing agent. C0 2 can be produced as a result of a reaction between an isocyanate and water, when water is included in a polyurethane foam formulation. The use of water and C0 2 can help reduce the amount of halogenated alkanes used in making a polyurethane foam. This can result in reducing the amount of halogenated alkanes released into the atmosphere, which can be desirable. Polyurethane foams can be made using water or a combination thereof C0 2 exclusively as the blowing agent. Such foams (hereinafter C0 2 -blown foams) are described in U.S. Patent No. 5,013J66, for example. C0 2 -blown foams can typically be high density foams, that is foams having an overall density greater than about 2.3 pounds per cubic foot (pcf). C0 2 -blown foams having low density can be obtained by conventional methods, but such foams can have low closed cell content. In certain applications where a low density polyurethane foam having high closed cell content is desirable, typical C0 2 -blown foams can be undesirable. In the art of preparing rigid polyurethane foams it would be desirable to prepare a low density C0 2 -blown foam having a high closed cell content. It would also be desirable in the art of preparing rigid foams to reduce leakage in a PIP procedure. In one aspect, the present invention is a polyurethane foam formulation comprising a polyisocyanate composition, .and a polyol composition, wherein the polyol composition includes: (a) at least one aromatic amine-initiated polyol; (b) at least one alkylene carbonate; and (c) water. In another aspect, the present invention is a low density C0 2 -blown foam prepared from a polyurethane foam formulation comprising a polyisocyanate composition and a polyol composition wherein the polyol composition includes: (a) at least one aromatic amine-initiated polyol; (b) at least one alkylene carbonate; and (c) water. In still another aspect, the present invention is A process for preparing a polyurethane-filled article comprising the steps: (i) pouring a polyurethane foam formulation into a mold; (ii) allowing the foam to fill the mold; and (iii) demolding the foam after the foam attains cure to obtain the polyurethane-filled article, wherein the polyurethane foam formulation comprises a polyisocyanate composition and a polyol composition and wherein the polyol composition includes: (a) at least one aromatic amine-initiated polyol; (b) at least one alkylene carbonate; and (c) water. Using the process of the present invention, the problem of leakage from a mold can be reduced when using a PIP procedure to prepare a foam. A C0 2 -blown foam obtained using the process of the present invention is a low density foam which can have a 15 percent to 30 percent reduction in overall density relative to foams produced by conventional practice. In one embodiment, the present invention is a foam formulation useful for preparing a C0 2 -blown foam. A foam formulation of the present invention includes a polyisocyanate composition and a polyol composition. When the polyisocyanate and polyol compositions are combined under suitable reaction conditions, a low density polyurethane foam of the present invention is obtained. A polyol composition of the present invention includes isocyanate reactive material, an alkylene carbonate, and water. In addition, optional components can be included in either or both components of the foam formulation. Isocyanate-reactive materials suitable for use in the practice of the present invention include aromatic amine-initiated polyols (AAPs). AAPs suitable for use in the practice of the present invention can be obtained commercially. For example, Voranol ® 391 ( ® Trade Designation of the Dow Chemical Co.) is a commercially available polyol suitable for the practice of the present invention. Voranol ® 391 is an aromatic amine initiated polyol prepared from o-toluene diamine, ethylene oxide and propylene oxide. Generally, AAPs can be obtained by reaction of an aromatic amine with an alkylene oxide under suitable reaction conditions of, for example, temperature, pH, and catalyst. For example, a suitable temperature range for preparing an AAP of the present invention can be from 100°C to 135°C. Preferably the temperature is in the range of from 110°C to 130°C. More preferably, the temperature is the range of from 120°C to 130°C, most preferably from 125°C to 130°C. An AAP of the present invention can be obtained at a pH in the range of from 7.5 to 12. Preferably, the pH is from 8 to 11.5. More preferably, the pH is from 8.5 to 11 , most preferably from 9 to 11. A catalyst can be included to obtain an AAP of the present invention. Catalysts suitable for preparing polyols of the present invention include, for example, dimethylcyclohexlamine, dimethylethanolamine, and diethylethanolamine, like compounds, and mixtures thereof; Group I and Group II metal hydroxides such as sodium hydroxide, calcium hydroxide, barium hydroxide, lithium hydroxide, like compounds and mixtures thereof. An AAP suitable for the practice of the present invention can have a molecular weight of from 425 to 900. Preferably, the molecular weight of an AAP is from 520 to 825. More preferably, the molecular weight of an AAP is from 560 to 640. Most preferably, the molecular weight of an AAP is from 560 to 590. The hydroxyl number of an AAP of the present invention can range from 250 to 530. Preferably the hydroxyl number is in the range of from 325 to 465. More preferably the hydroxyl number is in the range of from 350 to 450, most preferably from 380 to 430. The average functionality of an AAP of the present invention is preferably not less than 2. More preferably, the average functionality of an AAP is from 3 to 5. Most preferably, the average functionality is from 3.2 to 4.1. Polyols of the present invention are prepared from alkylene oxides and an aromatic amine initiator. Aromatic amines suitable for preparing an AAP of the present invention can include any di-, or poly-functional aromatic amine. Suitable aromatic amines include: the isomers of toluene diamine (TDA), which include 2,6-TDA, and 2,4-TDA, for example; isomers of methylene diamine (MDA) which include, for example, 2,2'-MDA, 2,4'-MDA, and 4,4'-MDA; oligomers of MDA which include, for example, mixtures of isomeric compounds having from 3 to 6 aromatic rings; alkyl derivatives of aromatic amines such as 4-methyl-2,6-TDA and isomers of dimethyl- MDA; halogenated derivatives of TDA such as 3-chloro-2,4-TDA; like compounds and mixtures of .any of these. Alkylene oxides suitable for use in the present invention include oxides having from 2 to 8 carbon atoms, preferably from 2 to 4 carbon atoms. For example suitable alkylene oxides can be ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3- butylene oxide, styrene oxide, epichlorohydrin, 3 -methyl- 1,2-butylene oxide, like compounds .and mixtures thereof. In the present invention, polymers and copolymers of propylene oxide are preferred. In a foam formulation of the present invention, an AAP can be present as the only polyol component in a polyol composition or, optionally, other polyols can be included in the composition. If included, other polyols can be present in an amount of from 1 to 50 percent, by weight, of total polyol. Preferably from 0 to 10 percent, by weight, of another polyol is included. Water is included in a polyol composition of the present invention in an amount of from 1 to 12 parts per 100 parts of AAP, by weight. Preferably, water is included in an amount of from 3 to 9 parts. More preferably, water is included in an amount of from 5 to 8, most preferably water is included in an amount of from 6.5 to 7.5 parts per 100 parts of AAP, by weight. An alkylene carbonate is included in a foam formulation of the present invention. An alkylene carbonate useful in the practice of the present invention is described by either of structures I or II: I II wherein R,, R 2 , R 3 , .and R, .are each independently hydrogen or a combination thereof alkyl substituents of I, and wherein R 5 and R^ are each independently alkyl substituents of II. Alkyl substituents of I or II can be alkyl groups having from 1 to 8 carbon atoms. Suitable alkyl substituents can be aliphatic, aromatic, cyclic or acyclic, substituted or unsubstituted. Examples of suitable alkyl substituents include: methyl, ethyl , n-propyl, iso-propyl, n-butyl, isobutyl, pentyl, hexyl, cyclohexyl, phenyl, hydroxyphenyl, phenylmethyl, methylphenyl, bromophenyl, chloromethyl, like compounds, .and mixtures thereof. For example, suitable alkylene carbonates can include: ethylene carbonate; propylene carbonate; butylene carbonate; styrene carbonate (or 1- phenylethylene carbonate); isobutylene carbonate; dimethyl carbonate; diethyl carbonate; di-t-butyl carbonate; dibenzyl carbonate; diphenyl carbonate; phenyl, ethyl carbonate; like compounds, and mixtures thereof. Alkylene carbonates suitable for use in the practice of the present invention are known and can be obtained commercially. The purity of an alkylene carbonate is not believed to be critical to the practice of the present invention. For example, propylene carbonate is commercially available as Arconate 1000™ from the Arco Chemical Co. at 99 percent minimum purity, but lower purity is not believed to interfere with the practice of the present invention. An alkylene carbonate of the present invention can be included in an amount of from 1 to 20 parts per 100 parts of AAP, by weight. Preferably, an alkylene oxide is included in an amount of from 3 to 15 parts of alkylene carbonate per 100 parts of AAP, by weight. More preferably, an alkylene carbonate is included in an amount of from 5 to 12 parts of alkylene carbonate per 100 parts of AAP, by weight. Most preferably, an alkylene carbonate is include in an amount of from 7 to 10 parts of alkylene carbonate per 100 parts of AAP, by weight. In the practice of the present invention, an alkylene carbonate can be included with either the polyol composition or the isocyanate composition. Optionally, the alkylene carbonate can be included as part of both the polyol and isocyanate compositions. Preferably, the alkylene carbonate is included in the polyol composition. Optional components can be included in a polyol composition of the present invention. For example, a polyol composition can optionally include copolymer polyols, polyester polyols, catalysts, fillers, crosslinkers, surfactants, cell openers, mold release agents, and flame retardants, for example. Examples of polyurethane catalysts suitable for preparing a polyurethane foam of the present invention are tertiary amine catalysts such as: triethylenediamine; N- methyl morpholine; dimethylethanolamine; pentamethyldimethylenetriamine; N-ethyl morpholine; diethylethanolamine; N-coco morpholine; l-methyl-4-dimethylaminoethyl piperazine; bis(N,N-dimethylaminoethyl)ether; similar compounds, and mixtures of any of these. Suitable catalysts for use with the present invention also include those which catalyze the formation of isocyanurates such as those mentioned in Saunders and Frisch, Polyurethanes. Chemistry and Technology in High Polymers Vol. XVI, pp. 94- 97 (1962). Such catalysts are referred to as trimerization catalysts. Examples of these catalysts include aliphatic and aromatic tertiary amine compounds, organometallic compounds, alkali metal salts of carboxylic acids, phenols and symmetrical triazine derivatives. Preferred catalysts are potassium salts of carboxylic acids such as potassium octoate and the potassium salt of 2-ethylhexanoic acid and tertiary amines such as, for instance, 2,4,6-tris(dimethyl aminomethyl) phenol. Amine catalysts are usually used in an amount of from 0.1 to 5, preferably from 0.2 to 3 parts per 100 parts of polyol composition, by weight. Organometallic catalysts are also suitable, and examples include organolead, organoiron, organomercury, organobismuth, and preferably organotin compounds. Most preferred are organotin compounds such as dibutyltin dilaurate, dimethyltin dilaurate, stannous octoate, stannous chloride and similar compounds. Organometallic compounds are usually used in an amount from 0.05 to 0.2 parts per 100 parts, by weight, of polyol composition. Examples of surfactants that can be optionally included are silicone surfactants, most of which are block copolymers containing at least one polyoxyalkylene segment and one poly(dimethylsiloxane) segment. Other surfactants include polyethylene glycol ethers of long chain alcohols, tertiary amine or alkanolamine salts of long chain alkyl sulfate esters, alkyl sulfonic esters and alkylaryl sulfonic acids. When used, 0.1 to 3, preferably 0.3 to about 1 part by weight of surfactant to 100 parts of polyol by weight is normally adequate. Surfact.ants prep.ared from ethylene oxide .and butylene oxide, as described in U.S. Appl. Ser. No. 08/342,299 (allowed July 23, 1996), are also useful in the practice of the present invention. Examples of crosslinkers are diethanolamine and methylene bis(o-chloroaniline) and similar compounds. The use of cell openers, mold release agents, flame retardants, fillers, and other additives are known in the art to modify the properties and aid in the processability of the foam, and can be desirable depending on the end-use application. A polyisocyanate composition includes a polyisocyanate. Any polyisocyanate or polyisocyanate mixture known in the art is suitable for the practice of the present invention. Useful polyisocyanates are described in U.S. Patent No. 4,785,027, for example. The polyisocyanate can be aliphatic or aromatic. Aromatic polyisocyanates suitable for use herein include: phenyl diisocyanate; 2,4-toluene diisocyanate; 2,6- toluene diisocyanate; ditoluene diisocyanate; naphthalene 1,4-diisocyanate; 2,4'- or a combination thereof 4,4'-diphenylmethane diisocyanate (MDI); polymethylene polyphenylenepolyisocyanates (polymeric MDI); like compounds, .and mixtures thereof. Suitable aliphatic polyisocyanates include: 1 ,6-hexamethylene diisocyanate; isophorone diisocyanate; 1,4-cyclohexyl diisocyanate; like compounds and mixtures thereof. Prepolymers prepared by reacting a polyol or chain extender with a polyisocyanate are suitable, as well. The polyisocyanate can be used in an amount suitable to prepare a polyurethane-forming composition with an isocyanate index of from 90 to 500. Preferably, the index is from 100 to 130. More preferably the isocyanate index is from 105 to 115. Most preferably, the isocyanate index is from 105 to 110. The isocyanate index is determined by dividing the number of equivalents of isocyanate by the number of equivalents of isocyanate-reactive material, and multiplying the ratio obtained by 100. A polyisocyanate of the present invention can have an average functionality of from 2.0 to 3.5. Preferably, the average functionality is from 2.5 to 3.3. More preferably, the average functionality is from 2.6 to 3.2. Most preferably, the average functionality is from 2.6 to 3.0. In another embodiment, the present invention is a method for preparing a polyurethane-filled .article by the PIP procedure, using a foam formulation described herein. Generally, in a PIP operation, foaming is typically delayed until the start of the reaction inside of a mold cavity. In the process of the present invention, a pre- expansion occurs as a foam formulation is initially poured into a mold, due to the presence of the alkylene carbonate. The alkylene carbonate present in a foam formulation of the present invention generates C0 2 during storage at controlled temperatures. The initial frothing prevents the foam from leaking from an unsealed mold, and the subsequent foaming enhances the mold-filling process. In the present invention, a polyurethane-filled article is obtained according to the steps: mixing a polyisocyanate composition and a polyol composition at a suitable isocyanate index as described herein; pouring the polyurethane-forming mixture into a mold; allowing the foam mixture to fill the mold to obtain a molded rigid foam; and, demolding the foam after the foam attains cure to obtain the polyurethane-filled article. In a process of the present invention, a polyol composition that includes an alkylene carbonate can be stored at a temperature of from 10°C to 60°C. Preferably, an alkylene carbonate-containing composition is stored at a temperature of from 16°C to 32°C, more preferably at a temperature of from 18°C to 27°C, and most preferably at a temperature of from 21°C to 24°C. In still another embodiment, the present invention is a low density C0 2 -blown foam prepared from a foam formulation described herein. A foam of the present invention has properties that are at least equivalent to foams made according conventional processes. One property of a foam that can be improved by using the process of present invention is the overall density of a foam, while maintaining foam dimensional stability. The overall density is the density of the entire molded rigid foam part. A foam made according to the process of the present invention can have an overall density of not greater than 10 pcf. Preferably, a foam of the present invention can have a density not greater than 5.0 pcf, more preferably 3.0 pcf. Most preferably, a foam of the present invention has a density of not greater than about 2.2 pcf. Another property of a foam that can be improved by using the process of present invention is the closed cell content of a foam. A foam obtained using the process of the present invention can have a closed cell content of not less than 80 percent. Preferably a foam of the present invention has a closed cell content of not less than 85 percent. More preferably the closed cell content is not less than 90 percent, most preferably not less than 92 percent. Of particular importance in the present invention is that a foam prepared according to the process of the present invention can have low density, suitable dimensional stability, and high closed cell content. Suitable dimensional stability for a foam of the present invention is from 0 to ± 8 percent volume change, for example. Preferably, the dimensional stability is from 0 to ± 6 percent volume change, most preferably from 0 to ± 4 percent volume change. A foam of the present invention additionally provides excellent adhesion to various substrates, for example plastic liner materials such as high impact polystyrene and high density polyethylene, as well as steel facers. At the same time, a foam of the present invention maintains excellent dimensional stability at a density of not less than 1.80 pcf under cold age, dry age, and humid age conditions. A foam of the present invention exhibits finer and more uniform cell structure than a conventionally prepared foam. Other attributes of the foam attributable to the process of the present invention are: low free rise density of less than about 1.10 pcf, preferably from 0.95 to 1.10, more preferably from 0.95 to 1.07, most preferably from 0.95 to 1.05 pcf; low core foam friability of not greater than about 3.0 percent, preferably from 1.0 percent to 3.0 percent, more preferably from 1.0 percent to 2.5 percent, most preferably from 1.0 percent to 2.0 percent; and fast demold. A foam prepared according to the process of the present invention generally can be demolded in less than about 8 minutes. Preferably, a foam of the present invention is demolded in from 3 minutes to 8 minutes, more preferably in from 3 minutes to 7 minutes. Most preferably, a foam of the present invention is demolded in from 3 minutes to 6.5 minutes. Demold time is dependent on the thickness of the foam obtained, and the ranges described herein are given for a foam thickness of about 1.75 inches. EXAMPLES The following examples and comparative example are meant to be illustrative of the present invention. These examples and comparative example are not intended to limit the scope of the claims of the present invention and they should not be interpreted in that manner. Example 1 A polyol composition was prepared by admixing polyol, propylene carbonate, and water with optional components in the amounts listed in Table 1. Example 2 A polyol composition was prepared by admixing polyol, propylene carbonate, and water with optional components in the amounts listed in Table 1. Example 3 - Comparative Example A polyol composition was prepared by admixing polyol and water with optional components in the amounts listed in Table 1. Example 4 - Comparative Example A polyol composition was prepared by admixing polyol and water with optional components in the amounts listed in Table 1. Example 5 - Comparative Example A polyol composition was prepared by admixing polyol and water with optional components in the amounts listed in Table 1. Example 6 - Comparative Example A polyol composition was prepared by admixing polyol and water with optional components in the amounts listed in Table 1. Example 7 The polyol composition of Example 1 was combined with 215 parts of P API ® 27 isocyanate to an isocyanate index of 105. The polyurethane-forming mixture thus produced was poured into a mold heated to a temperature of 130°F. The foam was removed from the mold after 4.5 minutes. Some physical properties of the foam was tabulated in Table 2. The foam reactivity profile was shown in Table 3. Foam physical properties was determined according to the following procedures: a. Foam In-place (overall) density was determined by the formula D = W/V, where D was the density of a foam, W was the weight of the foam, and V was the volume of the foam. b. Core density was determined according to ASTM D-1622. c. k-Factor was determined according to ASTM C-518. d. Compression Strength was determined by according to ASTM D-1621. d. Friability was determined according to ASTM D-421. e. Dimensional stability was determined according to ASTM D-2126. f. Closed cell content was determined according to ASTM D-2856. Example 8 - Comparative Example The polyol composition of Example 3 was combined with 173 parts of PAPI ® 27 isocyanate to an isocyanate index of 110. The polyurethane-forming mixture thus produced was poured into a mold heated to a temperature of 130°F. The foam was removed from the mold after 4.5 minutes. Some physical properties of the foam was tabulated in Table 2. The foam reactivity profile was shown in Table 3. Example 9 - Comparative Example The polyol composition of Example 4 was combined with 214 parts of PAPI ® 27 isocyanate to an isocyanate index of 110. The polyurethane-forming mixture thus produced was poured into a mold heated to a temperature of 130°F. The foam was removed from the mold after 4.5 minutes. Some physical properties of the foam was tabulated in Table 2. The foam reactivity profile was shown in Table 3. Example 10 - Comparative Example The polyol composition of Example 5 was combined with 173 parts of PAPI ® 27 isocyanate to an isocyanate index of 110. The polyurethane-forming mixture thus produced was poured into a mold heated to a temperature of 130°F. The foam was removed from the mold after 4.5 minutes. Some physical properties of the foam was tabulated in Table 2. The fo.am reactivity profile was shown in Table 3. Example 11 - Comparative Example The polyol composition of Example 6 was combined with 214 parts of PAPI ® 27 isocyanate to an isocyanate index of 110. The polyurethane-forming mixture thus produced was poured into a mold heated to a temperature of 130°F. The foam was removed from the mold after 4.5 minutes. Some physical properties of the foam was tabulated in Table 2. The foam reactivity profile was shown in Table 3. Example 12 The polyol composition of Example 1 was combined at 84°F with 215 parts of PAPI ® 27 isocyanate to an isocyanate index of 105. The polyurethane-forming mixture thus produced was poured into a mold heated to a temperature of 130°F. The foam was removed from the mold after 4.5 minutes. Some physical properties of the foam was tabulated in Table 2. The foam reactivity profile was shown in Table 3. Example 13 The polyol composition of Example 3 was combined with 173 parts of PAPI ® 27 isocyanate to an isocyanate index of 110. The polyurethane-forming mixture thus produced was poured into a mold heated to a temperature of 130°F. The foam was removed from the mold after 4.5 minutes. Some physical properties of the foam was tabulated in Table 2. The foam reactivity profile was shown in Table 3. Table 1 *Not an example of the present invention. + Vorasurf ® 504 ( ® Trade Designation of the Dow Chemical Co.) a Dimethylcyclohexylamine b Toyocat™ F94 (Trade Designation of Tosoh Corp.) c Curithane ® 52 (Trade Designation of the Dow Chemical Co.) Available from Akzo Chemical Co. Table 2 *Not an example of the present invention. @ 95 percent Relative Humidity ** No data. Properties not measurable due to collapse of foam. Table 3 Not an example of the present invention. "Hand Pour @ 72°F — No Data. Properties not measurable due to collapse of foam.

Claims: What is claimed is: 1. A polyurethane foam formulation comprising: (1) a polyisocyanate composition; and (2) a polyol composition, wherein the polyol composition includes: (a) at least one aromatic amine-initiated polyol; (b) at least one alkylene carbonate; and (c) water. 2. The polyurethane foam formulation of Claim 1 wherein the aromatic amine initiated polyol is prepared using an aromatic amine selected from the group consisting of: isomers of TDA; isomers of MDA; and oligomers of MDA. 3. The polyurethane foam formulation of Claim 2 wherein the aromatic amine is selected from the group consisting of: isomers of TDA; and, isomers of MDA. 4. The polyurethane foam formulation of Claim 3 wherein the aromatic amine is selected from isomers of TDA. 5. The polyurethane foam formulation of Claim 4 wherein the aromatic amine is o-TDA. 6. The polyurethane foam formulation of Claim 1 wherein the alkylene carbonate is selected from the group consisting of: ethylene carbonate; propylene carbonate; butylene carbonate; dimethyl carbonate; diphenyl carbonate; and, diethyl carbonate. 7. The polyurethane formulation of Claim 6 wherein the alkylene carbonate is propylene carbonate. 8. A low density C0 2 -blown polyurethane foam prepared from the polyurethane foam formulation of Claim 1. 9. The low density C0 2 -blown polyurethane foam of Claim 8 wherein the foam overall density is not greater than 5.0 pcf. 10. The low density C0 2 -blown polyurethane foam of Claim 9 wherein the foam overall density is not greater than 3.0 pcf. 11. The low density C0 2 -blown polyurethane foam of Claim 10 wherein the foam overall density is not greater than 2.2 pcf. 12. The low density C0 2 -blown polyurethane foam of Claim 8 wherein the foam has a closed cell content of not less than 85 percent. 13. The low density C0 2 -blown polyurethane foam of Claim 12 wherein the foam has a closed cell content of not less than 90 percent. 14. The low density C0 2 -blown polyurethane foam of Claim 13 wherein the foam has a closed cell content of not less than 92 percent. 15. A process for preparing a polyurethane-filled article_comprising the steps: (i) pouring the polyurethane foam formulation of Claim 1 into a mold; (ii) allowing the foam to fill the mold; and (iii) demolding the foam after the foam attains cure to obtain the polyurethane-filled article. 16. The process of Claim 15 wherein the foam is prepared by a PIP procedure, and wherein leakage from a mold is reduced relative to a PIP procedure in which a formulation of Claim 1 is not used. 17. The process of Claim 15 wherein the polyol composition is stored at a temperature of from 10°C to 60°C prior to combining with the polyisocyanate composition. 18. A polyurethane-filled article prepared by the process of Claim 15. 19. The polyurethane-filled article of Claim 18 wherein the article is a door; refrigerator; portable cooler; walk-in cooler; garage door; or water heater. 20. The polyurethane-filled article of Claim 18 wherein the article is a door.

Inventors: BHATTACHARJEE DEBKUMAR, MIRASOL SOL M, BHATTACHARJEE, DEBKUMAR, MIRASOL, SOL, M.
Applicants: BHATTACHARJEE DEBKUMAR, DOW CHEMICAL CO, MIRASOL SOL M, BHATTACHARJEE, DEBKUMAR, MIRASOL, SOL, M., THE DOW CHEMICAL COMPANY
Application year: 1998
Main classification: C08G18
IPC codes: C08G18, C08G101, C08K5