MXPA00010310A - Rigid polyurethane foams and method to form said foams using low molecular weight diols and triols - Google Patents

Abstract

The present invention is a polyurethane foam comprising the reaction product of a first reactant comprised of a polyisocyanate having an average isocyanate functionality of at least 2 and a second reactant comprised of a low molecular weight compound that has at least two to, at most, three groups containing an active hydrogen and water, wherein the reaction product is formed essentially in the absence of a cross-linking polyol and the polyurethane foam is substantially rigid. The invention is also a method of forming the polyurethanefoam by contacting the first and second reactant for a time and temperature sufficient to form the foam.

Description

RIGID RETAINED POLY U MATERIALS AND METHOD OF FORMING THESE UTI LIZAN SPUTS OF DIOLES AND WEIGHT TRIOLS MOLEC ULAR LOW.

FIELD OF THE INVENTION The invention relates to rigid polyurethane foams and methods for making rigid polyurethane foams.

BACKGROUND OF THE INVENTION Polyurethane foams are formed by the reaction of a polyisocyanate compound, such as toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI) with a polyhydroxyl compound, such as a polyol. Generally, the equal volume streams of the polyol (ie, the part of the polyol) and polyisocyanate (isocyanate) are intermixed in a mixing head and then injected into a mold where they react to form the polyurethane foam. Generally, the polyol part also contains water, surfactant, catalysts and aggregate blowing agents. Generally, there are two types of polyurethane foams: flexible and rigid. In general, flexible foams have open cell structures and a flexible polyurethane (for example, it uses a low functionality, high molecular weight polyol that allows them to deform elastically.) Generally, when a flexible polyurethane foam is made, water is used in the Part of the polyol as a blowing agent Water reacts with the isocyanate producing carbon dioxide that forms the polyurethane as the isocyanate and polyol react On the other hand, rigid foams generally have a substantially closed cell structure so essentially they are elastically deformed (ie, when a rigid foam is deformed, it is permanently deformed.) To provide stiffness, rigid polyurethane foams are typically formed using a lower molecular weight polyol than that used to make a flexible foam and also a flexible foam. degradation polyol Generally, the degradation polyol n has (1) a hydroxyl functionality greater than 3 to 8 (ie, typically greater than 3 to 8 hydroxyl groups / molecules that can react with the isocyanate), (2) an average molecular weight of 300 to 800 and viscosity elevated from 3000 to 20,000 centipoises. The degradation polyols are typically added to increase the degradation density to form a rigid foam of suitable strength and stiffness. Unfortunately, the use of high viscosity degradation polyols substantially increases the viscosity of the polyol portion. The increased viscosity of the polyol part typically makes it difficult to achieve effective mixing with the isocyanate portion of low viscosity, resulting in non-homogeneous rigid foams. Historically, liquid, low viscosity volatile organic compounds (ie, liquid aggregate blowing agents) have been used to reduce viscosity. However, this results in volatile organic compound (VOC) emissions when the foam is made. The degradation polyols also make it difficult to balance the volumes of the isocyanate portion and the polyol portion due to the high equivalent weight of the degradation polyol. This is especially true when the polyol part contains water due to its low equivalent weight of 9. Again, the volatile organic compounds are generally added to balance the volume of the polyol and isocyanate part and to blow the foam in the absence of water. In addition, the degradation polyols cause the foam to reach the "gel point" sooner than a foam formed without them. The point of gelation occurs when the viscosity of the foamed mass begins to increase exponentially due to the assembly of the polymer domains. Accordingly, rigid foams made with degradation polyols tend to split when made with water due to the internal gas pressure derived from the continuous evolution of CO2 after the foam has gelled. Consequently, the blowing agent for a rigid foam is generally either (1) a liquid volatile organic compound, such as chloromethane (eg, CFM-1 1), which volatilizes during the formation of the polyurethane causing foaming of the polyurethane or ( 2) a gaseous organic compound, such as chloromethane (eg, CFM-12), which is injected into the streams causing the streams to foam and consequently form the rigid foam. These blowing agents have generally been used to avoid one or more of the problems described above. However, they raise environmental and safety concerns.

BRIEF DESCRIPTION OF THE INVENTION Accordingly, it would be desirable to provide a rigid polyurethane foam that avoids one or more problems of the prior art, such as one or more of those described herein. A first aspect of the present invention is a method for forming a polyurethane foam comprising: contacting a first reactive agent comprised of at least 2 and a second reactive agent comprised of a low molecular weight compound having at least two up to, as maximum, three groups containing an active hydrogen in the presence of water for a sufficient time to form a substantially rigid foam, provided that the foam is formed essentially in the absence of a degradation polyol. A second aspect of the invention is a polyurethane foam comprising the reaction product of a first reactive agent of a polyisocyanate having an average isocyanate functionality of at least 2 and a second reactive agent comprised of a low molecular weight compound which it has at least two up to a maximum of three groups containing an active hydrogen and water, wherein the reaction product is formed essentially in the absence of a degradation polyol and the polyurethane foam is substantially rigid. A substantially rigid foam, herein, is a rigid foam as is understood in the art. For example, the substantially rigid foam generally has a closed cellular structure which essentially fails to deform elastically (i.e., any deformation of the foam tends to be permanent).

DETAILED DESCRIPTION OF THE INVENTION Herein, the degradation polyol has a hydroxyl functionality of greater than 3 (ie, greater than 3 hydroxyl groups / molecules that can react with the isocyanate) and a molecular weight of 300 to 800. Generally , the degradation polyol has a viscosity of 3000 to 20,000 centipoise. The foam formed essentially in the absence of the degradation polyol means that only residual amounts are found in the reaction mixture that forms the foam. Preferably there is no degradation polyol. By using a low molecular weight compound, such as propylene glycol, a substantially rigid polyurethane foam can surprisingly be formed in the absence of a degradation polyol. The foam may also be formed in the absence of a blowing agent other than CO2 produced from the water-polyisocyanate reaction. It is considered that the compound of low molecular weight reduces the rate of degradation and, consequently, the principle of stiffness of the foam that is formed. It is believed that this deceleration provides a sufficient time to essentially complete the evolution of the CO2 from the reaction of the isocyanate water in order to allow the foam to form without splitting, as occurs, for example, when the described degradation polyol is used. before. Furthermore, it is also considered that the use of the low molecular weight compound reacts more completely with the isocyanate groups, resulting in foams having generally higher compression ratios than those made with degradation polyols. In addition, due to the low equivalent weight of the low molecular weight compound, the first aspect of the invention can also advantageously be carried out using volumes of the first and second reactive agents which are similar, even when the second reactive agent contains an auxiliary polyol, such as a The polyether polyol subsequently deciphered although it maintains the isocyanate index close to one. Consequently, the method of the first aspect can be performed using standard polyurethane process equipment. The use of the low molecular weight compound having a low viscosity also results in the second reactive agent (ie, the polyo! Part) to have a viscosity similar to the known polyisocyanates. The similarity of viscosity allows the two reactants to mix and react to form a uniform and homogeneous more uniform foam. The method and foams produced in accordance with the present invention can be used and any suitable application, such as those known in the art, including applications involving, for example, automotive applications that require rigidity, reinforcement, decrease of NVH (noise, vibration and hardness) in a vehicle. The method according to the invention contacts a first reactive agent comprised of a polyisocyanate having a functionality of at least 2 and a second reactive agent, comprised of a low molecular weight compound, having at least two up to a maximum of three groups containing an active hydrogen in the presence of water. The polyisocyanate can be a suitable polyisocyanate for making a polyurethane foam, such as those known in the art. The polyisocyanate can be an aromatic or aliphatic polyisocyanate, polymeric isocyanate, aromatic diisocyanate, and aliphatic diisocyanate. Exemplary polyisocyanates include m-phenylene diisocyanate, tolylene-2-4-diisocyanate, tolylene-2-6-diisocyanate, hexamethylene-1,6-diisocyanate, tetramethylene-1,4-diisocyanate, cyclohexane-1,4-diisocyanate, hexahydrotolylene diisocyanate, naphthylene-1, 5-diisocyanate, methoxyphenyl-2,4-diisocyanate, diphenyl methane-4,4'-diisocyanate, 4,4'biphenyl diisocyanate, 3,3'-dimethoxy-4-diisocyanate, 4'-biphenyl, 3,3'-dimethyl-4,4'-biphenyl diisocyanate, 3,3 '-dimethyldif in 4-ylmetan-4,4'-diisocyanate, 4,4', 4"-triphenylmethane triisocyanate, polyphenylisocyanate polymethylene and tolyIen-2,4,6-triisocyanate, 4,4'-dimethyldiphenylmethane-2,2'5,5'-tetraisoclanate Preferably, the polyisocyanate is diphenylmethane-4,4'-diisocyanate (MDI), tolylene-2 -4-diisocyanate, tolylene-2-6-diisocyanate or mixtures thereof Tolylene-2-4-diisocyanate, tolylene-2-6-diisocyanate and mixtures thereof are referred to generally as TDI. Polyisocyanate is a polyisocy polymeric substance formed from MDI, such as those available from The Dow Chemical Company under the trademark PAPI ™. The polymeric polyisocyanate "PAPI 27" is particularly preferred. Generally, the average isocyanate functionality of the polyisocyanate is at least 2 to 6 at most. Preferably, the average isocyanate functionality of the polyisocyanate is at least 2.5, and more preferably at least 2.7 to preferably 3.5 at most, and most preferably 3.3 at most. As understood in the art, functionality is the average number of isocyanate groups per molecule in the polyisocyanate. To ensure adequate degradation, the low molecular weight compound (LMWC) has a functionality of at least 2 to 3 at most, wherein the functionality is the number of reactive sites of hydrogen equivalent (eg, amine) or hydroxyl per molecule (ie, the compound has at least two groups containing an active hydrogen). Generally, the LMWC groups are an amine, thiol or hydroxyl. The LMWC can be, for example, a diol, dithiol, hydroxyamine, hydroxy thiol, amino thiol or a diamine. The LMWC can be aliphatic or aromatic, preferring aliphatic. It is preferred that at least one of the groups is a primary group and at least one other group is a secondary group. For example, the propylene glycol has a primary hydroxyl and a secondary hydroxyl. It is considered that the presence of a secondary group reduces the speed of the reaction with the isocyanate and consequently, results in a foam that is easier to form without splitting. The LMWC groups are preferably hydroxyl groups. Exemplary LMWCs include propylene glycol, ethylene glycol, 1,4-butanediol, 1-6 hexanediol, resorcinol, hydroquinone, monoethanolamine, glycerin, trimethylolpropane, diethanolamine, triethanoiamine, diethylene glycol, dipropylene glycol, neopentyl glycol, bis (2-hydroxyethyl) hydroquinone or mixtures thereof. Preferably, the LMWC is propylene glycol, ethylene glycol or glycerin. More preferably, the LMWC is propylene glycol. Surprisingly, a substantially rigid foam and suitable degradation can be formed when an LMWC having a functionality of less than 3 (e.g., 2) is used in conjunction with a polyisocyanate having a functionality greater than 2: It is surprising since the degradation polyols are they comprise in the art as being compounds having a functionality greater than 3. The low molecular weight compound must also have a sufficiently low molecular weight to form a substantially rigid polyurethane foam. If the molecular weight is too high, a substantially rigid foam is not formed. Generally, the molecular weight of the LMWC is at most 200, preferably 150 at most, more preferably 100 at most up to at least 45. The amount of LMWC is also important in the formation of the foam. If the quantity is insufficient, the foam that forms can not be rigid. Generally, the amount of LMWC is at least 2.5 weight percent of the polyurethane reaction mixture (ie, all components used to make the foam). Preferably, the amount of the LWMC is at least 3 percent, more preferably at least 5 percent, still more preferably at least 7.5 percent, and most preferably at least 10 percent by weight of the polyurethane reaction mixture (is say, all the components used to make the foam). Generally, these amounts of LMWC correspond to the LMWC comprising at least 2.5 percent, preferably at least 6 percent, more preferably at least 10 percent and most preferably at least 15 percent by weight of the second reactive agent. Although the second reactive agent can be completely composed of the LMWC, it is preferred that the amount be less than 50 percent by weight of the second reactive agent so that the volume of the first reactive agent and the second reactive agent can be similar, as described in the present. Consequently, the second reactive agent can also contain an auxiliary polyol in addition to the LMWC. Herein, the auxiliary polyol can be a polyol, such as those described by U.S. Patent Nos. 3,383,351: 3,823,201; 4, 1 19.586 and 4, 148.840. Exemplary auxiliary polyols include polyhydroxyalkane polyols, polytetrahydrofuran polyols, polyoxyalkylene polyols, alkylene oxide addition products of non-reducing sugars and sugar derivatives, alkylene addition products of phosphorus and polyphosphoric acids, oxide addition products of alkylene of polyphenols and polyols derived from natural oils, such as vinegar oil. Preferably, the polyols are glycols, triols or polyols of higher functionality of poly (oxybutylene), poly (oxyethylene), poly (oxypropylene), poly (oxypropylene-oxyethylene) or mixtures thereof. Generally, these polyols have a molecular weight of at least 300. It is understood that the auxiliary polyols used in the present invention are incapable of forming a substantially rigid foam in the absence of the LMWC (i.e. they are not degradation polyols as described in FIG. I presented). For example, the auxiliary polyol may have an average functionality greater than 2, but the chain length of the auxiliary polyol is of a length and functionality that fails to cause a sufficient amount of degradation to make a substantially rigid foam. The auxiliary polyol may have a hydroxyl number that varies over a wide range depending on the desired properties of the polyurethane foam. In general, the auxiliary polyol can have a hydroxyl number ranging from 20 to 1000. Preferably, the hydroxyl number is at least 25, and more preferably at least 30 to preferably 600 at most, and most preferably 450 at most. The hydroxyl number is defined as the number of milligrams of potassium hydroxide required for the complete hydrolysis of the fully acetylated derivative prepared from 1 gram of polyol. The method can also be carried out in the presence of catalysts such as those described by U.S. Patent No. 4,390,645, in column 10, lines 14 through 27; surfactant agents, such as those described by the U.S. Patent. No. 4,390,645, in column 10, lines 28 to 43; chain extension agents. Such as those described by the Patent of E. U. No. 4, 390, 645, in column 10, lines 59 to 68, and column 10, lines 1 to 5; fillers, such as calcium carbonate and pigments, such as titanium dioxide, iron oxide, chromium oxide, azo / diazo dyes, phthalocyanines, dioxazines and carbon black. The method can also be carried out in the presence of a flame retardant, such as those known in the art, and can include, for example, phosphoric compounds, halogen-containing compounds and melamine. More specifically, representative catalysts include: '(a) tertiary amines, such as trimethylamine, triethylamine, N-N-methylmorpholine. N-ethylmorpholine, N, N-dimethylbenzylamine, NN-dimethylethanolamine, N, N, N ', N'-tetramethyl-1,4-butanediamine, N. N -dimethylpiperazine, 1,4-diazobicyclo [2.2.2] octane, bis (dimethiaminoethyl) ether and triethylenediamine; (b) tertiary phosphines, such as trialkylphosphines and dialkylbenzylphosphines; (c) chelates of various metals, such as those obtainable from acetylacetone, benzoylacetone, trifluoroacetylacetone, ethyl acetoacetate with metals, such as Be, Mg, Zn, Cd, Pd, Ti, Zr, Sn, As, Bi , Cr, Mo, Mn, Fe, Co and Ni; (d) acidic metal salts of strong acids, such as ferric chloride, stannic chloride, stannous chloride, antimony trichloride, bismuth nitrate and bismuth chloride; (e) strong bases, such as hydroxides, alkoxides and metal phenoxides of alkali and alkaline earth; (f) alcoholates and phenolates of various metals, such as Ti (OR) 4, Sn (OR) and AI (OR) 4, wherein R is alkyl or aryl and the reaction products of the alcoholates with carboxylic acids, beta- diketons and 2- (N, N-dialkylamino) alcohols; (g) salts of organic acids with a variety of metals, such as alkali metals, alkaline earth metals, Al, Sn, Pb, Mn, Co, ni and Cu including, for example, sodium acetate, stannous octoate, oleate tin, lead octoate, metal driers, such as manganese and cobalt naphthenate; (h) organometallic derivatives of tetravalent tin, trivalent and pentavalent As, Sb and Bi and iron and cobalt metal carbonyls and (i) mixtures thereof. The catalysts are typically used in small amounts, for example, each catalyst employed from 0.0015 to 1 weight percent of the polyurethane reaction mixture (ie, all components used to make the foam). Particular examples of surfactants include nonionic surfactants and wetting agents, such as those prepared by the sequential addition of propylene oxide and then ethylene oxide to propylene glycol, solid or liquid organosilicones, polyethylene glycol ethers of alcohols. of long chain, tertiary amine or alkylamine salt of long chain alkyl sulfate esters, alkyl sulphonic ester and alkyl arylsulfonic acids. The surfactants prepared by the sequential addition of propylene oxide and then of ethylene oxide to propylene glycol and the liquid or solid organosilicones are preferred. More preferred are liquid organosilicones which are not hydrolysable. Examples of non-hydrolyzable organosilicones include those available under the trademarks DABCO ™ DC 5043, DABCO ™ DC 5169 and DABCO ™ DC 5244, available from Dow Corning Corp., Freeland, Ml and TEGOS ™ B-8404 and TEGOS ™ 8462 available from Th. Goldschmidt Chemical Corp., Hopewell, VA. Surfactants are typically used in small amounts, for example, from 0.0015 to 1 weight percent of the polyurethane reaction mixture (ie, all components used to make the foam). When the foam is formed, it is preferred that only the blowing agent is essentially the CO2 produced by the isocyanate water reaction. Another blowing agent may be present, such as a low-boiling hydrocarbon, such as pentane, hexane, heptane, pentene and heptene, directly added carbon dioxide, an azo compound, such as azohexahydrobenzodnitrile or a halogenated hydrocarbon, such as dichlorodifluoroethane , vinylidene chloride and methylene chloride. Generally, the amount of these blowing agents is small. Preferably, the amount of these blowing agents is at most a residual amount and more preferably none at all (ie, the only blowing agent is CO2 generated in situ from the isocyanate water reaction). The foam can be made by any suitable method, such as those known in the art. The method may include, for example, prepolymer (described in U.S. Patent No. 4,390,645), a shot (described in U.S. Patent No. 2,866,744) or foaming (described in U.S. Patent Nos. 3,755,212; 3,849, 156 and 3,821, 130). The first reactive agent and the second reactant are contacted for a sufficient time to form the substantially rigid polyurethane foam without splitting. Generally, the time is as short as practicable and can be from 1 to 60 minutes. The reaction temperature may be any sufficient to form the foam without splitting but should not be so large as to decompose the polyurethane foam. Usually, the temperature ranges from room temperature to 200 ° C. When the foam is formed, it is preferred that the volumes of the first reactive agent and the second reactive agent be similar so that the typical polyurethane foaming apparatus can be used. Generally, the volume ratio of the first reactive agent to the second reactive agent is at least 0.7, more preferably at least 0.8, and most preferably at least 0.9 to preferably 1.3 at most, more preferably 1.2 at most and most preferably 1. .1 maximum. The second reactive agent, in addition to containing the LMWC and the polyol, may contain, for example, a catalyst, filler, water, flame retardant and surfactant. Because the LMWCs generally have a low viscosity, the present invention allows a more uniform mixture of the ppmer and second reactive agents than the prior art. The improved mixture provides a more uniform foam (ie, more consistent cell size and structure) and homogeneous foam. The viscosity of the second reactive agent containing the LMWC generally has a viscosity that is within 0.5 to 1.5 times the viscosity of the first reactive agent (ie, the polyisocyanate used). Preferably, the viscosity of the second reactive agent is at least 0.7, more preferably at least 0.8, and most preferably at least 0.9 to preferably 1.3 at most, more preferably 1.2 at most and most preferably 1.1 at most, times the viscosity of the first reactive agent (ie, the polyisocyanate). In the absence of an inert diluent, the apparent viscosity of the second reactive agent is preferably within a range of 50 to 300 centipoise. More preferably, the viscosity is 250 centipoise maximum and most preferably 200 centipoise maximum in the absence of an inert diluent. Here, an inert diluent is a liquid that lowers the viscosity of the second reactive agent but fails to affect the urethane reaction or reacts with either hydroxyl or isocyanate groups. Examples of inert diluents may include blowing agents, such as CFCs (chlorofluorocarbons) or plasticizers, such as phthalates. When the foam is formed, the amount of polyisocyanate and, consequently, other reactive agents used in the manufacture of the polyurethane is commonly determined by the isocyanate index. The isocyanate index can be determined by the equation: Current Isocyanate Amount Used Isocyanate Index Theoretical Amount of Isocyanate The theoretical equivalent amount of isocyanate is the stoichiometric amount of isocyanate required to react with the polyol and some other reactive additives, such as water. The socianato index can vary over a range depending on the desired foam characteristics. Generally, a higher index produces a harder foam. In the production of rigid foams of this invention, the isocyanate index typically ranges from 0.7 to 1.4. Preferably, the index is at least 0.75, more preferably at least 0.8, even more preferably at least 0.85, and most preferably at least 0.9 to preferably 1.35 at most, more preferably at 1.3 as a maximum, even more preferably at 1.25. at most, and most preferably 1 .2 at most. If desired, a large excess in the isocyanate can be used to make, for example, an isocyanurate foam.

The substantially rigid foam that is formed can have a large range of properties, depending on the particular application that is desired. For example, the foam may have a density per unit volume of 80 to 800 kilograms per cubic meter. Foam can also have a wide range of compression strengths depending on, of course, the density and particular components used. For example, the foam may have a compressive strength of 7.03 to 351.5 kilograms per square centimeter (689 to 34.474 kilopascals) and a compression ratio of 140.6 to 7030 kilograms per square centimeter (13,790 to 68,948 kilopascals). The following are specific examples within the scope of the invention and comparative examples. The specific examples are found for illustrative purposes only and do not limit in any way the invention described herein.

EXAMPLES Example 1 First, a second reactive agent (ie, the part of the polyol) was made by mixing together the components shown in Table 1. The components were mixed for 15 minutes at 700 rpm using a turbine mixer available from INDCO, New Albany, IN. The second reactive agent had a viscosity of 220 centipoise ("cps") (.220 pascal seconds). Using a Gusmer low pressure shock distributor (Gusmer Corp., Akron, OH), the second reagent was mixed at 35.18 kilograms per square centimeter (3,447 kilopascals) and at 48.9 ° C with 120 parts by weight ("pbw") of PAPI ™ 27 and distributed in an open container where the mixture formed a foam. PAPI 27 is a polymeric polyisocyanate MDI having an average isocyanate functionality average of 2.7, average molecular weight of 360 and a viscosity of 180 cps. PAPI 27 is available from The Dow Chemical Co., Midland, Ml. The foam formed without splitting. The resulting rigid foam had a free-forming density of 86.56 kilograms per cubic meter (149.47 grams per cubic centimeter) and a compressive strength of 8.85 kilograms per square centimeter (868 kilopascals), as determined in accordance with ASTM D-1261 , procedure A. Example 2 The foam of Example 2 was made by the same method described in Example 1 except that the components of the polyol part are different, as shown in Table 1. The amount of PAP1 27 used was 17 pbw and PAPI 27 and the second reagent was mixed by hand for 15 seconds in the foaming vessel using the turbine mixer. The foam formed without cuts. The resulting foam had a free-forming density of 22.44 kilograms per cubic meter (0.022 grams per cubic centimeter) and was dimensionally stable, as determined by measuring the dimensions of a foam sample (2 inches (5.08 cm) * 2 2C). inches (5.08 cm) * 1 inch (2.54 cm)) before and after heating for 1 5 minutes in an oven maintained at 120 ° C. EXAMPLE 3 The foam of Example 3 was made by the same method described in Example 1 except that the components of the polyol part were different, as shown in Table 1, and the amount of PAPl 27 was 1 16 pbw. The foam formed without cuts. The resulting rigid foam had a density of free formation of 107.4 kilograms per cubic meter (0. 1 07 grams per cubic centimeter) and compressive strength of 8.85 kilograms per square centimeter. (868 kilopascals). Comparative Example 1 The foam of Comparative Example 1 was made by the same method described in Example 1 except that the components of the polyol part were different, as shown in Table 2, and the amount of PAPI 27 was 1 15. pbw. The foam broke during the formation. Comparative Example 2 The foam of Comparative Example 1 was made by the same method described in Example 1 except that the components of the polyol part were different, as shown in Table 2, and the amount of PAPI 27 was 1 1 7 pbw. The foam broke during the formation.

Table 1 Part of the Polyol of Examples 1 -3 I N3 VORANOL and DEH 39 available from The Dow Chemical Co., Midland, Ml. The POLYCAT and DABCO products available from Air Products and Chemical Inc., Allentown, PA. TEGOSTAB B-8404 available from Th. Goldshmidt Co., Hopewell, VA.

Table 2 Part of the Polyol of the Comparative Examples N3 N3 VORANOL is available from The Dow Chemical Co., Midland, Ml. The POLYCAT and DABCO products available from Air Products and Chemical Inc., Allentown, PA. TEGOSTAB B-8404 available from Th. Goldshmidt Co.

From Examples 1 and 2 a rigid foam was formed in the absence of a degradation polyol and in the absence of a blowing agent other than CO2 generated in situ. Meanwhile, the foams of Comparative Examples 1 and 2 employing a degradation polyol are split.

Claims (24)

1 . A polyurethane foam comprising the reaction product of a first reactive agent comprised of a polyisocyanate having an average social functionality of at least 2 and a second reactive agent comprised of a low molecular weight compound having at least two such maximum, three groups containing an active hydrogen, and having a molecular weight of 200 at most, an auxiliary polyol having a molecular weight of at least 300, a hydroxyl number of from about 20 to 1000 having a chain length and functionality such that it does not degrade the foam in a manner that does not impact the stiffness of the foam, and water, characterized in that the reaction product is formed essentially in the absence of a degradation polyol having a functionality greater than three and a molecular weight of 300 to 800 where the polyurethane foam is substantially rigid, closed cell and has a density of from 80 to 800 kilograms per cubic meter).

2. The foam according to claim 1, characterized in that the reaction product is formed essentially in the absence of a blowing agent different from the CO2 formed in situ.

3. The foam according to claim 1 or 2, characterized in that the groups of the low molecular weight compound are amine, thiol or hydroxyl. The foam according to any of claims 1 to 3, characterized in that the low molecular weight compound has two groups containing an active hydrogen and the polyisocyanate has a functionality greater than two. The foam according to any of claims 1 to 4, characterized in that the low molecular weight compound is propylene glycol, ethylene glycol, 1 -4-butanediol, 1-6 hexanediol, resorcinol, hydroquinone or monoethanolamine. 6. The foam according to any of claims 1 to 5, characterized in that the low molecular weight compound is propylene glycol, ethylene glycol or glycerin. The foam according to any of claims 1 to 6, characterized in that the first reactive agent and the second reactive agent are contacted in a volume ratio of the first reactive agent to the second reactive agent of from 0.7 to 1.3. 8. The foam according to any of claims 1 to 7 ,. characterized in that at least 10 weight percent of the second reactive agent is the low molecular weight compound. 9. The foam according to any of claims 1 to 8, characterized in that one of the groups in the low molecular weight compound is a primary group and the other is a secondary group. A method for forming a polyurethane foam according to any of claims 1 to 9, characterized in that it comprises: contacting the first reactive agent and the second reactive agent for a sufficient time to form a substantially rigid foam of closed cells provided that the foam is formed essentially in the absence of a degradation polyol having a functionality greater than 3 and a molecular weight of 300 to 800. The method according to claim 1, characterized in that the low molecular weight compound is propylene glycol, ethylene glycol, 1 -4-butanediol, 1 -6 hexanediol, resorcinol, hydroquinone, monoethanolamine, glycerin, trimethylolpropane, diethanolamine, triethanolamine, pentaerythritol or mixtures thereof. The method according to claim 1, characterized in that the low molecular weight compound is propylene glycol, ethylene glycol or glycerin. The method according to claim 12, characterized in that the low molecular weight compound is propylene glycol. The method according to claim 1, characterized in that the first reactive agent and the second reactive agent are contacted in a volume ratio of the first reactive agent to the second reactive agent of from 0.7 to 1.3. 15. The method according to claim 1 1, characterized in that the volume ratio is from 0.8 to 1.2. 16. The method according to claim 1, characterized in that the second reactive agent further comprises an auxiliary polyol. The method according to claim 16, characterized in that at least 10 weight percent of the second reactive agent is the low molecular weight compound. 18. The method according to claim 1, characterized in that the amount is at least 1.5 percent by weight of the second reactive agent. The method according to claim 1, characterized in that the method is carried out essentially in the absence of a blowing agent different from CO2 produced in situ. 20. A polyurethane foam made by the method according to claim 1. twenty-one . A polyurethane foam comprising the reaction product of a first reactive agent comprised of a polyisocyanate having an average isocyanate functionality of at least 2 and a second reactive agent comprised of a low molecular weight compound having at least two up to, at most three groups containing an active hydrogen and water, characterized in that the reaction product is formed essentially in the absence of a degradation polyol and the polyurethane foam is substantially rigid. 22. The foam according to claim 21, characterized in that the reaction product is formed essentially in the absence of a blowing agent different from the CO2 formed in situ. The foam according to claim 21, characterized in that the low molecular weight compound is propylene glycol, ethylene glycol, 1,4-butanediol, 1-6 hexanediol, resorcinol, hydroquinone or monoethanolamine. 2

4. The foam according to claim 23, characterized in that the low molecular weight compound is propylene glycol.