WO1998027132A1

WO1998027132A1 - The use of butylene oxide (bo) based polyols to improve the compatibility of pentane and cyclopentane in rigid polyurethane foams

Info

Publication number: WO1998027132A1
Application number: PCT/US1997/023803
Authority: WO
Inventors: Debkumar Bhattacharjee; Dwight David Latham; Gilbert L. Nelson; C. R. Leigon
Original assignee: The Dow Chemical Company
Priority date: 1996-12-19
Filing date: 1997-12-19
Publication date: 1998-06-25
Also published as: BR9714225A; TR199901335T2; CA2274652A1; KR20000057648A; AR010844A1; JP2001505941A; HUP9904649A3; PL333975A1; CO4890879A1; HUP9904649A2; EP0946620A1

Abstract

The present invention is a formulated polyether or polyester polyol blend that is useful for preparing polyurethane and polyisocyanurate foams. The formulated polyol blend of the present invention includes: a polyol that is derived from butylene oxide; and a hydrocarbon blowing agent such as pentane or cyclopentane, for example. Use of butylene oxide polyols of the present invention allow inclusion of a sufficient amount of a hydrocarbon blowing agent to produce foams having low density, without incorporating a higher concentration of water into a polyurethane foam formulation.

Description

THE USE OF BUTYLENE OXIDE (BO) BASED POLYOLS TO IMPROVE THE COMPATIBILITY OF PENTANE AND CYCLOPENTANE IN RIGID POLYURETHANE FOAMS

Polyether polyols can be used in the preparation of polyurethane and 5 polyisocyanurate foams (foams), and are typically prepared from propylene oxide and/or ethylene oxide, using initiators such as sucrose, sorbitol, or glycerol, for example. Polyurethane foams prepared from polyether polyols are used in a variety of applications, including construction, appliance, automotive, and carpet applications. Rigid foams, in particular, are used in appliance and construction applications, for

10 example. A polyol blend used to prepare polyurethane foam formulations can include a blowing agent, in addition to other components. Blowing agents can be used to create cellular structures within a foam. Some conventional blowing agents, such as halogenated hydrocarbons, for example, can be perceived as harmful to the environment.

15

Polyester polyols can be used in the preparation of polyurethane and polyisocyanurate foams (foams), and can be typically prepared from ethylene glycol derivatives and/or propylene glycol derivatives, for example, and carboxylic acid and/or carboxylic acid derivatives (hereinafter carboxyl components) such as phthalic

20 anhydride, dimethyl terephthalate, and adipic acid. Polyurethane foams prepared with polyester polyols are used in a variety of applications, including construction, appliance, shielding, and pour-in-place applications. A formulated polyester polyol blend used to prepare polyurethane foam formulations can include a blowing agent, in addition to other components. A blowing agent can be used to create cellular structures

25 within a foam. Some conventional blowing agents, such as halogenated hydrocarbons, for example, can be perceived as harmful to the environment, and replacement of such halogenated hydrocarbons is desirable in certain circumstances.

Non-halogenated hydrocarbon blowing agents, that is, hydrocarbon blowing 30 agents (HCBAs) are important alternatives to traditional halogenated hydrocarbon blowing agents. Hydrocarbons such as pentane and cyclopentane have been used successfully as blowing agents in polyurethane systems, and are not believed to harm the ozone layer of the atmosphere. The use of hydrocarbons as blowing agents is demonstrated in, for example, U.S. Patent No. 3,072,582. The use of hydrocarbon blowing agents can present problems, however.

Insolubility of hydrocarbon blowing agents in polymer formulations can lead to processing problems, particularly in producing polyurethane and polyisocyanurate foam products, for example. Hereinafter, it is to be understood that for the purposes of the present invention, "polyurethane" can refer to both polyurethane polymers as well as to polyisocyanurate polymers. Solubility of HCBAs can be poor in polyol blends, particularly those which incorporate aromatic polyester polyols. The possibility of phase separation of HCBAs from a foam formulation makes it necessary to take measures to maintain a homogeneous mixture or dispersion when HCBAs are used. One way of using HCBAs in conventional polyol blends can be to limit the amount of HCBA included in a polyol blend to a low concentration, in order to avoid separation of the HCBA from the mixture. While separation of the HCBA can be avoided, the amount of blowing agent actually included in a polyurethane foam formulation can be an important factor in determining the quality of a polyurethane foam product. Having too low a concentration of blowing agent in a foam formulation can detrimentally affect the quality of a foam. For example, using too little blowing agent can cause the density of the foam to be too high. To prepare a low density foam, that is, a foam having a density of less than 2.5 lbs per cubic foot (pcf), it can be necessary to include more water than would otherwise be desirable when using conventional blowing agents. Increasing the amount of water in a foam formulation can detrimentally affect the dimensional stability and long-term thermal conductivity of a foam due to the relatively fast rate of diffusion of carbon dioxide from a foam, compared with a hydrocarbon or halogenated hydrocarbon blowing agent. HCBAs such as pentane and cyclopentane can be particularly incompatible with polyols substantially prepared using ethylene oxide and/or propylene oxide. Aromatic polyester polyols can incorporate only a limited amount of HCBAs. Surfactants can aid in making the components of a polyol blend compatible, but are not completely helpful in making HCBAs compatible in a polyol blend.

It would be desirable in the art of preparing polyurethane foams to utilize hydrocarbon blowing agents in a polyurethane foam formulation. It would be desirable in the art of preparing polyurethane foams to utilize a hydrocarbon blowing agent in a polyurethane foam formulation that includes polyester polyols. It would also be desirable in the art of preparing polyurethane foams to make a low density foam from a polyurethane foam formulation that includes hydrocarbon blowing agents but does not require additional water in the formulation. Finally, it would be desirable in the art of preparing polyurethane foams to include hydrocarbon blowing agents in a foam formulation at a concentration that will yield a low density foam, wherein the hydrocarbon blowing agent does not phase separate from the formulation.

In one aspect, the present invention is a polyether polyol blend comprising: a polyol substantially derived from butylene oxide, and at least one HCBA, wherein solubility of the HCBA in the polyol is increased by at least 30% over HCBA solubility in a polyol not substantially derived from butylene oxide.

In another aspect, the present invention is a foam prepared from a polyether polyol blend wherein the polyether polyol blend comprises: a polyol substantially derived from butylene oxide, and at least one HCBA, wherein solubility of the HCBA in the polyol is increased by at least 30% over HCBA solubility in a polyol not substantially derived from butylene oxide.

In still another aspect, the present invention is a process for preparing a foam comprising the steps: (1) forming a reactive mixture by admixing a polyisocyanate with a polyether polyol blend, wherein the polyether polyol blend comprises: a polyol derived substantially from butylene oxide; a catalyst; a surfactant, and at least one HCBA, wherein solubility of the HCBA in the polyol is increased by at least 30% over HCBA solubility in a polyol not substantially derived from butylene oxide; (2) pouring the reactive mixture into a mold; (3) allowing the reactive mixture to cure to a tack-free foam; and (4) optionally removing the foam from the mold.

In another aspect, the present invention is a formulated polyol blend comprising: a polyester polyol which comprises a carboxyl portion and a oxyalkylene portion wherein: (a) the oxyalkylene portion of the polyol is derived substantially from butylene oxide; and (b) the hydrocarbon blowing agent is present at least 1 part per 100 parts by weight of the composition.

In another aspect, the present invention is a polyurethane rigid foam prepared using as one component a formulated polyol blend comprising: a polyester polyol which comprises a carboxyl portion and a oxyalkylene portion wherein: (a) the oxyalkylene portion of the polyol is derived substantially from butylene oxide; and (b) the hydrocarbon blowing agent is present at least 1 part per 100 parts by weight of the composition.

In still another aspect, the present invention is a process for preparing a foam comprising the steps: (1) forming a reactive mixture by admixing a polyisocyanate with a formulated polyol blend, wherein the polyol blend comprises: a polyester polyol which comprises a carboxyl portion and a oxyalkylene portion wherein: (a) the oxyalkylene portion of the polyol is derived substantially from butylene oxide; and (b) the hydrocarbon blowing agent is present at least 1 part per 100 parts by weight of the composition; (2) pouring the reactive mixture; and (3) allowing the reactive mixture to cure to a tack-free foam. In one embodiment, the present invention is a formulated polyether polyol blend (polyether polyol) useful for preparing polyurethane and polyisocyanurate foams. A polyether polyol of the present invention includes a polyol and at least one HCBA, together with optional components. Polyols useful in the practice of the present invention are polyether polyols substantially derived from 1 ,2-butylene oxide (butylene oxide), including aliphatic and aromatic polyether polyols. For example, Bisphenol-A can be modified to obtain a polyol that is useful in the practice of the present invention. Polyols of the present invention can be prepared exclusively from butylene oxide monomer, or from mixtures of butylene oxide with other oxide monomers. For example, polyether polyols of the present invention can be prepared from a combination of butylene oxide and alkylene oxides having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, and 2,3-butylene oxide. A polyol of the present invention is substantially derived from butylene oxide if it includes at least 25 percent by weight butylene oxide. Preferably, a polyol of the present invention is substantially derived from butylene oxide if it includes at least 50 percent, more preferably at least 70 percent, and most preferably at least 80 percent by weight of the polyol is derived from butylene oxide. Polyols substantially derived from butylene oxide (BO polyols) can be reacted with isocyanate groups under conditions suitable for preparing a polyurethane.

Polyols of the present invention can be prepared by methods known and practiced in the art of preparing polyether polyols. Such methods are described, for example, in U.S. Patent Number 3,153,002. Generally, a polyol of the present invention can be prepared by reacting butylene oxide and an initiator in the presence of a catalyst. The ratio of initiator to alkylene oxide can be any ratio that is effective for making polyols suitable for use in the present invention, and will depend on the targeted molecular weight and functionality of the base polyol. The catalyst can be alkaline or acidic. Polyols of the present invention can be prepared, for example, by combining butylene oxide, with an initiator such as ethylene glycol or propylene glycol, in the presence of a catalyst. Catalysts suitable for use in the practice of the present invention include, for example, amine compounds such as dimethylcyclohexylamine, dimethylethanolamine, and diethylethanolamine, like compounds, and mixtures thereof; Group I and Group II metal hydroxides such as sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, lithium hydroxide, like compounds and mixtures thereof. Particularly preferred are: potassium hydroxide, trimethylamine, and dimethylcyclohexylamine.

The catalyst can be present in an amount from 1 percent to 10 percent, preferably from 2 percent to 8 percent, more preferably from 2 percent to 6 percent based on the weight of the initiator. Elevated temperature can advantageously be employed to effect the polymerization. A suitable temperature can be any temperature above 100 °C. Preferably the temperature range is from 100°C to 135°C. More preferably the temperature range is from 110°C to 130°C. Most preferably the temperature range is from 120°C to 130 °C.

Examples of initiators useful in the practice of the present invention include active hydrogen containing compounds. Active hydrogen containing compounds are compounds having functionality wherein at least one hydrogen atom is bonded to an electronegative atom such as sulfur, nitrogen, or oxygen. Active hydrogen containing compounds useful herein can contain any combination of hydroxyl, amino, and mercaptyl functionality. Examples of such materials include those selected from the following classes of compositions, alone or in admixture: (a) polyhydroxyalkanes; (b) non-reducing sugars and sugar derivatives; (c) polyphenols; and amines. Examples of polyhydroxyalkanes useful herein include ethylene glycol, propylene glycol, 1 ,3- dihydroxypropane, 1 ,4-dihydroxybutane, and 1 ,6-dihydroxyhexane, glycerol, 1,2,4- trihydroxybutane, 1 ,2,6-trihydroxyhexane, 1,1,1-trimethylolethane, 1,1,1- trimethylolpropane, pentaerythritol, polycaprolactone, xylitol, arabitol, sorbitol, manitol, like compounds and mixtures thereof. Examples of sugars and sugar derivatives useful as initiators in the practice of the present invention include sucrose; fructose; mannose; galactose; glucose; like compounds and mixtures thereof. Alkyl and aryl ethers having at least one active hydrogen, and alkylene oxide adducts of sugars are also useful herein. Compounds derived from phenols such as bisphenols such as 2,2-(4,4'-hydroxyphenyl)propane; alkylphenols such as dodecylphenol, octylphenol, decylphenol; and polyphenols derived from condensation of formaldehyde with phenols, like compounds and mixtures thereof are also suitable for forming the polyols useful in the practice of the present invention. Particularly preferred initiators are polyhydroxy compounds such as glycerol, sugars such as sucrose, like compounds and mixtures thereof.

Polyols of the present invention can be prepared from alkylene oxides and an amine initiator or mixture of amine initiators. Aliphatic amines can be suitable for use as an initiators in the practice of the present invention and include, for example, ethylenediamine, ethanolamine, diethylenetriamine, aminoethylethanolamine, like compounds and mixtures thereof. Aromatic amines can also be suitable for preparing a polyol 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; halogentated derivatives of TDA such as 3-chloro-2,4- TDA; like compounds and mixtures of any of these.

Polyols of the present invention can have a molecular weight in the range of from 200 to 3500. Preferably, the molecular weight of a polyol of the present invention is in the range of from 250 to 2500. More preferably, the molecular weight is from 250 to 2000, most preferably from 250 to 1500. The functionality of the polyols of the present invention can be greater than 2.0. Preferably the functionality is from 2.5 to 7.5. More preferably from 3 to 7.5, most preferably from 3.1 to 7.

In another embodiment, the present invention is a formulated polyester polyol blend useful for preparing polyurethane and polyisocyanurate foams. A formulated polyol blend of the present invention includes at least one polyester polyol and at least one HCBA, along with other optional components. The polyol portion of polyester polyols useful in the practice of the present invention are substantially derived from butylene oxide diols (butylene glycols). Other polyols are useful in the practice of the present invention, as well. Polyester polyols of the present invention can be prepared by reacting carboxylic acids and/or carboxylic acid derivatives (which will hereinafter be referred to collectively as carboxyl components) with polyols substantially derived from butylene oxide.

Carboxyl components suitable for the practice of the present invention include: dicarboxylic acids, such as adipic acid, phthalic acid, isophthalic acid, terephthalic acid, like compounds, and mixtures of any of these; carboxylic acid anhydrides, such as phthalic anhydride, like compounds, and mixtures of any of these; dicarboxylic acid esters such as dimethyl terephthalate, like compounds, and mixtures of any of these.

Alternatively, polyester polyols of the present invention can be prepared by reacting carboxyl components with polyols substantially derived from butylene oxide in combination with: polyols having from 2 to 8 carbon atoms; oligomeric polyols having molecular weight within the range of from 60 to 7500; or any mixtures of these. An oligomeric polyol mixture of the present invention can have a bimodal molecular weight distribution. Preferably, the molecular weights of oligomeric polyols used herein are from 60 to 165 and from 300 to 7500; more preferably from 100 to 165 and from 300 to 7000; most preferably from 100 to 165 and from 300 to 6,800. For example, polyester polyols of the present invention can be prepared from a combination of butylene oxide polyols with: ethylene glycol; propylene glycol; and 1 ,2-cyclohexane diol; 1,6-hexane diol; or mixtures of any of these.

Polyols used to prepare the polyester polyols of the present invention can have functionality of from 2.0 to 3.0. Preferably the functionality is from 2.0 to 2.6, more preferably from 2.0 to 2.4, most preferably from 2.0 to 2.3. Polyols used to prepare polyester polyols of the present invention can include from at least 40 percent to 100 percent by weight butylene glycol monomeric units. Preferably, from 50 to 100 percent, more preferably from 70 percent to 100 percent, and most preferably from 80 percent to 100 percent by weight of the polyol is derived from butylene glycol monomer. Polyols of the present invention can be optionally chain-extended by reacting the polyol with an alkylene oxide, by conventional methods known in the art. Polyols substantially derived from butylene oxide (BO polyols) can be reacted with isocyanate groups under conditions suitable for preparing a polyurethane.

Polyester polyols of the present invention can be prepared using an excess of low molecular weight glycols and/or polyols, which can be advantageous in the process of manufacturing the polyester polyols. Excess of the low molecular weight glycols and polyols can be useful as solvent or diluent in the process of manufacturing the polyester polyols. The excess polyols can also act to lower viscosity in a polyurethane foam formulation, thereby aiding in the process of making a polyurethane foam. Excess glycol and/or polyol can be added at any convenient time in the process of preparing polyols or foams of the present invention. For example, excess glycol or polyol can be added before or after the polyol is obtained in the process described herein.

Polyester polyols of the present invention can be prepared by methods known and practiced in the art of preparing polyols. Such methods are described, for example, in U.S. Patent Number: 5,169,877; 4,439,549; 4,444,918 and 4,469,824. Polyester polyols of the present invention can have a molecular weight in the range of from 200 to 3500. Preferably, the molecular weight of a polyester polyol of the present invention is in the range of from 250 to 2500. More preferably, the molecular weight is from 250 to 2000, most preferably from 250 to 1500.

Blowing agents of the present invention include non-halogenated hydrocarbons having 2 to 8 carbon atoms. Suitable hydrocarbon blowing agents include the saturated isomers and the unsaturated isomers of: ethane; propane; butane; pentane; hexane; heptane; and, octane. For example, n-butane, isobutane, pentane, isopentane, 2-methyl pentane, and 2,2-dimethylpentane, like compounds, and mixtures thereof, are suitable for use herein. Cyclic hydrocarbon blowing agents are useful in the practice of the present invention. For example, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane and cyclooctane, cyclopentene, cyclohexene, cyclohexadiene, cyclopentadiene, methylcyclohexane, like compounds, and mixtures thereof, can be used in the invention described herein. Oxygenated hydrocarbons are also useful as blowing agents, in the practice of the present invention. Examples of oxygenated blowing agents include alkyl ethers having from 2 to 12 carbon atoms. Suitable alkyl ethers include, for example, dimethyl ether; diethyl ether; ethyl, methyl ether; diisopropyl ether; ethyl, isopropyl ether; like compounds, and mixtures thereof. Preferred blowing agents are butane, isobutane, pentane, isopentane, and cyclopentane.

Blowing agents of the present invention can be combined with a polyol in any proportion that can yield a polyol blend having a homogeneous single phase. By "homogeneous single phase mixture", it is meant that the polyol blend does not separate into two distinct phases or layers. The polyol blend is a stable mixture in that the blowing agent does not separate from the polyol within a 2 to 7-day period. A polyol blend of the present invention can include any amount of HCBA that is effective in producing a low density polyurethane foam. A polyether polyol blend of the present invention can include at least 8 parts per hundred parts of polyol. Preferably, a polyether polyol of the present invention can include at least 12 parts, more preferably at least 14 parts, and most preferably at least 15 parts per hundred parts of polyol.

The solubility of a HCBA is increased in a polyol that is substantially derived from butylene oxide relative to the solubility of a HCBA in a comparable polyol that is not substantially derived from butylene oxide. For the purposes of the present invention, comparable polyols are polyols that have similar equivalent weights and functionality. The equivalent weight and functionality of a polyol can be determined by methods known and practiced by those skilled in the art of preparing polyols. In the present invention, the solubility of a HCBA in a polyol substantially derived from butylene oxide can be increased by at least 30%. Preferably the solubility is increased by at least 45%, more preferably by at least 50%. Even more preferably the solubility is increased by at least 75%, and most preferably by at least 100%

Alternatively, a portion of a blowing agent can be included in an isocyanate component of a polyurethane-forming mixture. From 0 percent to 100 percent of the blowing agent can be included in the isocyanate. Preferably, from 0 percent to 75 percent of the blowing agent is included in the isocyanate. More preferably from 0 percent to 50 percent, and most preferably from 0 to 25 percent of the blowing agent is included in the isocyanate.

A formulated polyol blend used in a polyurethane-forming mixture of the present invention can include optional components. The polyol blend of the present invention can include, for example, polyurethane catalysts, surfactants, flame retardants, water, fillers, pigments, and cross-linkers.

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 moφholine; diethylethanolamine; N-coco morpholine; 1 -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. Surfactants prepared 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. A surfactant can be optionally included in the polyol formulation or in a polyisocyanate composition. When used, 0.1 to 3, preferably 0.2 to 2.5 part by weight of surfactant to 100 parts of polyol by weight is normally adequate.

Examples of crosslinkers are diethanolamine and methylene bis(o- chloroaniline), similar compounds and mixtures thereof. 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.

In still another embodiment, the present invention is a polyurethane-forming mixture that is prepared from the combination of an isocyanate mixture and a formulated polyol blend. The terms "isocyanate" and "polyisocyanate" are used interchangeably herein, with the caveat that isocyanate compounds useful in the practice of the present invention contain at least two isocyanate moieties per molecule. Polyisocyanates used in the present invention are not unique. Any isocyanate known and used in the art of preparing polyurethane polymers is suitable for the practice of the present invention.

Useful isocyanates are described in U.S. Patent No. 4,785,027, for example. Examples of suitable isocyanates include: the isomers of toluene diisocyanate (TDI) such as 2,4-toluene diisocyanate and 2,6-toluene diisocyanate; prepolymers of TDI, wherein prepolymers of TDI are compounds known in the art to be useful in preparing polyurethane foams; oligomeric mixtures of MDI, wherein the mixture includes MDI and oligomers of MDI having 3 or more aromatic rings; bis(4- isocyanatophenyl)methane (MDI); prepolymers of MDI, wherein prepolymers of MDI are compounds known in the art to be useful in preparing polyurethane foams; oligomeric mixtures of MDI; bis(isocyanatoethyl fumerate); dianisidine diisocyanate; toluidine diisocyanate; 1 ,6-hexamethylene diisocyanate; and mixtures of at least any two suitable compounds of this type. Preferred are TDI, MDI, prepolymers of TDI, prepolymers of MDI, oligomeric mixtures of MDI, or such mixtures of any of these. In another embodiment, the present invention is a polyurethane foam prepared using the polyether polyols of the present invention. A polyurethane foam of the present invention can be prepared by conventional methods, the improvement being the use of the BO polyols and a HCBA to prepare the foams. In general, a polyurethane foam of the present invention can be prepared by reacting a polyol formulation with an isocyanate mixture. A polyurethane-forming reactive mixture can be poured into a mold, or alternatively processed either by injection molding or reaction injection molding (RIM). Injection molding and RIM are described, in Macromolecules-2, Hans- Georg Elias ed., (2nd ed., 1984). Foams of the present invention can be prepared by block-foam, double-band lamination, discontinuous panel, or pour-in-place processes. Each process is well known in the art of preparing polyurethane foams. Polyurethane foams prepared according to the present invention can be useful in construction appliance, automotive, and caφet applications.

EXAMPLES

The following examples and comparative example were meant to be illustrative of the present invention. These examples and comparative example were not intended to limit the scope of the claims of the present invention and they should not be inteφreted in that manner.

Example 1

108 pounds of butylene oxide was added, with stirring, at a rate of 0.1 lb/min to a slurry composed of 28.73 lbs of sucrose, 22.5 lbs of glycerol, and 1.2 lbs of dimethylethanolamine. The addition was carried out at 120°C. The polyol mixture was stirred at 120°C for an additional 4 hours after all of the butylene oxide was added. The polyol had a viscosity of 1735 centistokes at 100°F, and a percent hydroxyl (%OH) of 14.95. The hydroxyl equivalent weight (eq. wt.) was 114. Example 2

The solubility of n-pentane and cyclopentane (c-pentane) in a polyol sample was determined by first measuring from between 50 to 100 grams of the polyol into a 4 oz container. The samples were conventional propylene oxide based polyols and their BO-based analogs. The BO-based polyols have the same equivalent weight as the PO- based analog. The hydrocarbon solute was added to the polyol sample. The container was capped to prevent the loss of blowing agent and then slowly heated until a clear solution was obtained. The container was allowed to cool to room temperature, and the appearance of a cloudy mixture was indication that the solubility of the solute was exceeded in that sample. If the solution remains clear, additional solute was added and the procedure repeated until a cloudy mixture was obtained. In this test a cloudy mixture was taken as indication that the polyol will separate into two layers in less than two days. The solubility reported in Table 1 was the highest concentration of solute, in parts per hundred parts (parts) based on the weight of the polyol, that yields a clear solution after the sample cools to room temperature.

Table 1

Not an example of the present invention. "Completely soluble in all proportions

Example 3

A polyol blend was prepared by admixing 85 parts of Terate™ 2541 (available from Cape Industries) and 15 parts of the BO polyol prepared in Example 1, 2.5 parts of EP-250™ (available from Goldschmidt Chemical Corp.), 2.2 parts of DABCO™ K-15 (available from Air Products), 0.6 parts of Pelron™ 9650 (available from Pelron Coφ.), 0.5 parts of Polycat™ 5 (available from Air Products), and 0.5 parts water. To this blend was added 21.6 parts of cyclopentane. The mixture was stirred until a homogeneous blend was obtained. To this blend was added 229.2 parts of PAPI^® 580 (Trademark of The Dow Chemical Co.), and the resulting reactive mixture was immediately mixed for 10 seconds using a high speed mixer. The mixture was poured into a cup and allowed to expand to form a rigid foam.

Example 4

A polyol blend was prepared by mixing: 75 parts of Voranol^® 490 (Trade designation of The Dow Chemical Co., eq. wt. 114); 12.5 parts of Voranol^® 800 (Trade designation of The Dow Chemical Co.); 12.0 parts of methyldiethanolamine; 0.5 parts of aminoethylethanolamine; 1.5 parts of Polycat™ 5; 1.0 part of TMR™ 5 (available from Air Products); 1.0 part of Toyocat™ MR (available from Tosoh, Inc.); 3.0 parts of Dabco™ DC 5357 (available from Air Products); 1.59 parts of water; and 18.5 parts of cyclopentane. To this blend was added 198.8 parts of PAPI^® 27 and the mixture was mixed immediately with a high speed mixer. The mixture was poured into a 9" x 2" x 16" mold which was heated to 50°C, and the mixture allowed to expand to form a rigid foam. A sample of the polyol blend used to make this foam separated on standing within 24 hours.

The foam was tested for compressive strength (X, Y), core density, dimensional stability (freeze (-30°) and humid age (158°C), and K-factor. Compressive strength was determined according to ASTM D-1621. Dimensional stability was determined according to ASTM D-2126, and the data reported in Table 2 were after 28 days. K- factor was determined according to ASTM C 518-85. Core density was determined according to ASTM D-1622. The foam properties were reported in Table 2.

Example 5 The procedure of Example 4 was repeated. The physical properties of the foam were reported in Table 2.

Example 6

The procedure of Example 4 was repeated. The physical properties of the foam were reported in Table 2.

Example 7

The procedure of Example 4 was repeated, except that 75 parts of the BO polyol described in Example 1 was used. The sample of the polyol blend used to make this foam did not separate on standing within 7 days. The physical properties of the foam were reported in Table 2.

Example 8

The procedure of Example 7 was repeated. The physical properties of the foam were reported in Table 2.

Example 9

Table 2

Example 10

A mixture of dimethyl terephthalate (1 mol), 1,2-butylene glycol (1.44 mol), titanium (IV) isopropoxide (2 mL), and VORASURF^* 504 ('Trademark of The Dow Chemical Company) (0.14 mol) was heated to a temperature of 215°C and held at that temperature for 6 hours. Methanol was distilled as it was formed in the reaction mixture as the transesterification reaction progresses. The transesterification was carried out until nearly complete to obtain a mixture that was composed of approximately 20 wt % of various VORASURF* 504 transesterification products (*Trademark of The Dow Chemical Co.).

Examples 11 - 16

Polyurethane foam formulations were prepared by admixing the components in Table 3 in the proportions indicated by the table. Formulated polyol blends were prepared by mixing polyester polyols, catalysts, fire retardant, surfactant, and water. To the blends were added isopentane. The resulting mixtures were stirred until homogeneous blends were obtained. To the blends were added a mixture of PAPI^® 580 (^®registered Trademark of The Dow Chemical Co.) and isopentane (isopentane was used in Examples 12 - 16, HCFC-141b was used as the blowing in Example 11), and the resulting reactive mixtures were immediately mixed for 8 seconds using a high speed mixer. The mixtures were poured into boxes and allowed to expand to form rigid foams. Physical properties of the foams were reported in Table 4. Test methods used were reported in Table 5. Table 3 Polyurethane Foam Formulations

"The concentrations of the components were in parts per 100 parts of polyol, by weight. ^bNot an example of the present invention.

Trademark of The Dow Chemical Co.

'Phthalic anhydride based polyester polyol, Hydroxyl No. 238, functionality of 2.0; from Stepan Co.

²Dimethyl terephthalate based experimental polyol from Ex. 1 , Hydroxyl No. 378.5, functionality of 2.0.

³Potassium octoate based catalyst, available from the Moody Co.

⁴Catalyst available from Air Products.

⁵Fire retardant available from AKZO Nobel.

⁶Surfactant available from Goldschmidt Chemical Corp.

⁷Fluorocarbon blowing agent available from Elf Altochem.

⁸Polymeric MDI, THAT IS = 139.0

Table 4 Physical Properties

"Not an example of the present invention.

Table 5 Test Methods

Example 17

Experimental polyester polyol D of the present invention were prepared according to the following procedure. A mixture of dimethyl terephthalate (194g, 1.0 mole), 1,2- butylene glycol (137.7g, 1.53 mole) and titanium (IV) isopropoxide (2 mL) as catalyst was slowly heated to 190°C, with continuous removal of methanol. After 6 hours of heating at 190 - 200°C, the reaction mixture was cooled and enough 1,2-butylene glycol was added to bring the OH# to 315 or 235. Experimental polyester polyols E and F were prepared analogously. The solubility of n-pentane and cyclopentane measured as described below.

The solubility of hydrocarbon blowing agent in several polyols was determined according to the following procedure. 75 grams of polyol was added to a clear glass jar. Hydrocarbon was added in 1 gram increments and the sample was vigorously mixed and allowed to set for several hours. As the solubility limit was approached the hydrocarbon additions were decreased to 0.5 grams. After determining to solubility limit, a mixture of polyol and hydrocarbon at the solubility limit was observed for phase separation over a several day period. The results were reported in Table 6.

Table 6 Hydrocarbon Solubility in Polyester Polyols

"Not an example of the present invention. ^bAvailable from Hoechst-Celanese. ^cAvailable from Stepan Co.

Example 18

Polyurethane foams were prepared from Polyol B and Polyol F according to the following procedure. Polyurethane foam formulations were prepared by admixing the components in Table 5 in the proportions indicated by the table. Formulated polyol blends were prepared by mixing polyester polyols, catalysts, surfactant, and water. To the blends were added cyclopentane. The resulting mixtures were vigorously stirred. To the resulting blends was added PAPI^® 580 (^®registered Trademark of The Dow Chemical Co.) and the resulting reactive mixtures were immediately mixed for 10 seconds using a high speed mixer. The mixtures were poured into boxes and allowed to expand to form rigid foams. The foam properties were determined and were reported in Table 7. Table 7 Laminate Foams Prepared From Polyester Polyols

"Not an example of the present invention. Trademark of The Dow Chemical Co.

Claims

CLAIMSWhat is claimed is:

1. A polyether polyol blend useful for preparing polyurethane foams comprising:

(a) a polyol substantially derived from butylene oxide; and

(b) at least one hydrocarbon blowing agent (HCBA), wherein the HCBA and the polyol form a homogeneous single-phase mixture.

2. The polyether polyol of Claim 1 wherein the polyol is at least 25 percent, by weight, derived from butylene oxide.

3. The polyether polyol of Claim 1 wherein the solubility of the HCBA in the polyol is increased by at least 30% over HCBA solubility in a polyol not substantially derived from butylene oxide.

4. A process for preparing a polyurethane foam comprising the steps:

(a) forming a reactive mixture by admixing a polyisocyanate with a polyether polyol blend comprising: a polyol derived from butylene oxide; a catalyst; a surfactant; and at least one HCBA, wherein the solubility of the HCBA in the polyol is increased by at least 30% over HCBA solubility in a polyol not substantially derived from butylene oxide;

(b) pouring the reactive mixture into a mold; and (c) allowing the reactive mixture to cure to a tack-free foam; and

(d) optionally removing the foam from the mold.

5. A composition comprising a polyester polyol which comprises a carboxyl portion and a oxyalkylene portion wherein: (a) the oxyalkylene portion of the polyol is derived substantially from butylene oxide; and (b)the hydrocarbon blowing agent is present at least 1 part per 100 parts by weight of the composition.

6. The polyol blend of Claim 5 wherein the oxyalkylene portion of the polyester polyol is at least 25 percent, by weight, derived from butylene oxide.

7. The polyol blend of Claim 5 wherein the blend includes at least 6 parts of HCBA, or blends thereof.

8. The polyol blend of Claim 5 wherein the solubility of the HCBA in the polyol is increased at least 30% over HCBA solubility in a polyol not substantially derived from butylene oxide.

9. A process for preparing a foam comprising the steps: (1) forming a reactive mixture by admixing a polyisocyanate with a formulated polyol blend, wherein the polyol blend comprises: a polyester polyol which comprises a carboxyl portion and a oxyalkylene portion wherein: (a) the oxyalkylene portion of the polyol is derived substantially from butylene oxide; and (b)the hydrocarbon blowing agent is present at least 1 part per 100 parts by weight of the composition; (2) pouring the reactive mixture; and

(3) allowing the reactive mixture to cure to a tack-free foam.

10. The process of Claim 9 wherein the blend includes at least 6 parts of HCBA, or mixtures thereof.

11. A polyurethane rigid foam prepared using as one component a formulated polyol blend comprising: a polyester polyol which comprises a carboxyl portion and a oxyalkylene portion wherein: (a) the oxyalkylene portion of the polyol is derived substantially from butylene oxide; and (b)the hydrocarbon blowing agent is present at least 1 part per 100 parts by weight of the composition.

12. A polyester polyol comprising a carboxyl portion and a oxyalkylene portion wherein: (a) the oxyalkylene portion of the polyol is substantially derived from butylene oxide; and (b) the oxyalkylene portion has a molecular weight in the range of from 60 to 7500.

13. A process for preparing a polyester polyol wherein a dicarboxylic acid and/or a dicarboxylic acid derivative is reacted with an oxyalkylene polyol or oxyalkylene polyol mixture, wherein the oxyalkylene oxide is substantially derived from butylene oxide; and (b) the oxyalkylene oxide or oxyalkylene oxide mixture has a molecular weight in the range of from 60 to 7500.

14. A polyester polyol obtained from the process of Claim 13.