MXPA06004934A - Rigid polyurethane foam based on toluene diamine-initiated polyols - Google Patents

Abstract

Rigid polyurethane foams are made using a polyol component that includes toluene diamine-initiated polyols containing specified levels of oxyethylene groups. Foams made from these polyols have low k-factors and excellent demold expansion values.

Description

RIGID POLYURETHANE FOAM, BASED ON PQLIQLES INITIATED WITH TOLUENODYAMINE The present invention relates to formulations and methods for the formation of rigid polyurethane foams, particularly foams poured on the site, which are used as thermal insulation in appliances and other applications. Rigid polyurethane foams are commonly used as thermal insulating materials in appliances such as refrigerators, freezers or chillers, or as insulation for ceilings and walls, and in other applications. An advantage of polyurethane foams in these applications is the possibility that they are formed in situ by reacting and foaming a polyurethane reaction mixture in the space in which the insulation is desired. The resulting rigid foam exhibits good thermal properties and frequently also provides certain structural benefits. Pouring the polyurethane foam formulations on site must meet several demands. The reactive formulation must be able to completely fill the available space, before the polymerization reaction is completed, using small amounts of raw materials; but provide a foam with good thermal insulation properties. Additionally, it is convenient that the formulation cures rapidly to form a dimensionally stable foam. Rapid curing to a dimensionally stable state allows manufacturing times and costs to be reduced. Additionally, the thermal insulation properties, commonly referred to as "factor k", correlate to some extent with the rapid initial reaction (gel time) of the foam formulation. Foam formulations of this type generally include a polyisocyanate component, a polyol component that is reactive with the polyisocyanate, a blowing agent, one or more surfactants and, usually, a catalyst. In general, the polyol component is a material or a mixture of materials having an average hydroxyl number of 300 to 600, and an average of three or more hydroxyl groups per molecule. Occasionally an amino alcohol, having both hydroxyl groups and primary or secondary amine groups, can form the entire polyol component, or a part thereof. Polyols initiated with toluene diamine (TDA) have been studied for use in these polyurethane applications. Propylene oxide has been added to the toluene diamine to form a polyol with hydroxyl number 300 to 600. It has been found that these polyols are extremely viscous, so much so, that they are very difficult to process consistently and reliably, on commercial scale equipment. In addition, the high pressures required to process these polyols in foam forming equipment reduces equipment life and increases maintenance costs. As a result there have been various attempts to produce a product of lower viscosity by reacting TDA with mixtures of ethylene oxide and propylene oxide. The polyol products initiated with TDA, which have viscosity below 5,000 MPa-S have been satisfactorily produced in that manner. In recent years, when concern for damage to the ozone layer has increased, preference has been given to alternative blowing agents instead of the traditional chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) blowing agents; having the alternative blowing agents lower potential for damage to the ozone layer and, in many cases, lower global warming potentials. Carbon dioxide (generated in a reaction of water with an isocyanate), various hydrofluorocarbons, with various hydrocarbons, and mixtures thereof, are now the replacement blowing agents that are selected. However, these are not thermal insulators as efficient as CFC and HCFC materials. As an example, CFC-11 and HFC-141b have thermal conductivities of 0.00377 cal / sec-2.54 cm-0.55 ° C (0.054 and 0.066 BTU / hr-in- F) in 77, respectively, while HFC-134a has 0.0074 cal / sec-2.54 cm-0.55 ° C (0.106 BTU / hr-in- F) and HFC245fa has 0.0067 cal / sec-2.54 cm-0.55 ° C (0.096 BTU / hr) -in- ° F). Despite this fact, governmental and / or industrial regulations frequently require that the devices containing these foams meet the same standards for thermal insulation that existed before. This means that the foam formulations need to be optimized to provide the required thermal insulation, despite the use of less efficient blowing agents. The problem is further complicated by the fact that alternative blowing agents are rarely complete replacements of CFCs and HCFCs. Due to the variations in their molecular weights, their boiling temperatures, their solubilities and other properties, the substitution with the most recent blowing agents almost always requires other adjustments in the formulation. Accordingly, it is desirable to provide a polyurethane foam formulation that can be easily processed to rigid, thermally insulating, high quality foam utilizing certain hydrofluorocarbon and / or hydrocarbon blowing agents. In one aspect, this invention is a method for forming a polyurethane foam, comprising: (1) forming a reaction mixture, by mixing, under reaction conditions: (a) an isocyanate-reactive component containing a polyol or a mixture of them, which has an average hydroxyl number of 300 to 600, an average of at least 3 hydroxyl groups per molecule; with (b) an isocyanate component containing a polyisocyanate that is reactive with the polyol, or a mixture thereof; in the presence of an effective amount of a physical blowing agent, selected from the group consisting of hydrofluorocarbons having from 2 to 4 carbon atoms; aléanos having 3 to 6 carbon atoms, and cycloalkanes having 5 or 6 carbon atoms; or a mixture of any two or more of the above physical blowing agents; and from 0.1 to 4 parts by weight of water per 100 parts by weight of the polyol or its mixtures; and (2) subjecting the reaction mixture to such conditions, that it reacts, expands and cures within a closed space, to form a rigid polyurethane foam within said closed space; wherein at least 10 weight percent of the polyol or a mixture thereof is one or more polyethers initiated with toluene diamine containing a hydroxyl group; where the polyether or the polyethers initiated with toluene diamine have an average hydroxyl number of 300 to 600; and further, wherein the oxyethylene groups (-CH2-CH2-O-) constitute from 2 to 25 percent, preferably from 2 to 20 percent, of the total weight of the polyether or the polyethers initiated with toluene diamine. In a second aspect, this invention is an isocyanate-reactive composition, comprising: (a) an isocyanate-reactive component containing a polyol, or a mixture thereof, having an average hydroxyl number of 300 to 600, and an average of at least three hydroxyl groups per molecule; (b) an effective amount of a physical blowing agent, selected from the group consisting of hydrofluorocarbons having from 2 to 4 carbon atoms; aléanos having 3 to 6 carbon atoms, and cycloalkanes having 5 or 6 carbon atoms; or a mixture of any two or more of the above physical blowing agents; and (c) from 0.1 to 4 parts by weight of water per 100 parts by weight of the polyol or mixture thereof; wherein at least 10 weight percent of the polyol or mixture thereof is one or more polyethers initiated with toluene diamine, which contain a hydroxyl group; polyether or polyethers initiated with toluene diamine have an average hydroxyl number of 300 to 600; and the oxyethylene groups constitute from 2 to 25 percent, preferably from 2 to 20 percent of the total weight of the polyether or the initiated polyethers with toluene diamine. The isocyanate reactive component includes one or more polyols which, taken together, have an average hydroxyl number of from 300 to 600, preferably from 400 to 600. The polyether or polyethers initiated with toluene-diamine (TDA) may constitute only a minor portion (10 to 49 percent of the total weight of the polyols) However, the benefits of this invention are more clearly seen when the polyether or polyethers initiated with TDA constitute at least 50 percent of the total weight of the polyols Polyether or polyethers initiated with TDA preferably constitute at least 70 percent, more preferably at least 75 percent, still more preferable, at least 80 percent of the total weight Polyether or initiated polyether (s) with TDA can constitute up to 90 percent, 95 percent, 98 percent, or 100 percent of the total weight of the polyols. the initiated polyethers (s) ) with TDA contains (n) oxyethylene groups, which constitute 2, preferably 3, more preferable, 5, more preferable, 6, up to 25, preferably up to 20, more preferable up to 17, more preferable still, up to 15; and in some applications up to 12 percent of the total weight of polyethers initiated with TDA. When the oxyethylene groups appear at the end of a polyether chain, they form primary hydroxyl groups. In these applications it is preferred that the terminal hydroxyl groups are mainly secondary hydroxyl. The secondary hydroxyl groups can be formed by "crowning" the polyether with an oxide of 1, 2-higher alkylene, such as propylene oxide or butylene oxide. Thus, the polyethers initiated with TDA used here are preferably polyethers having internal blocks of poly (oxyethylene), or internal blocks of EO / OP (ethylene oxide / propylene oxide) randomly copolymerized, which are crowned with a block of OP, to provide secondary hydroxyl groups, mainly terminals. It is preferred that at least 50 percent, more preferably, at least 80 percent, still more preferable, at least 90 percent, especially at least 95 percent, of the hydroxyl groups be secondary. The proportions of ethylene oxide to propylene oxide are such that the oxyethylene content and the hydroxyl number are both within the ranges mentioned above.

The polyether (or polyether mixture) initiated with TDA advantageously has a viscosity of less than 10,000 cps at 50 ° C, preferably less than 5,000 cps at 50 ° C, and in particular, less than 3,000 cps at 50 ° C. It is within the scope of the invention to use a mixture of polyethers initiated with TDA, in which one or more of the individual components is outside the oxyethylene group content mentioned above, as long as the polymerized ethylene oxide content, on average , of the mixture, is within the previously mentioned oxyethylene and hydroxyl number scales. For example, it is possible to use a mixture of a TDA adduct fully with OP with other polyols initiated with TDA having oxyethylene groups, as long as the oxyethylene content and the hydroxyl number of the mixture are within the scales indicated above. In such cases, one of the polyethers initiated with TDA in the mixture may contain a somewhat higher proportion of oxyethylene groups than indicated above; again with the condition that the average oxyethylene content and the hydroxyl number of the mixture fall within the scales indicated above. For example, an adduct of TDA totally with OP, can be combined with a polyol initiated with TDA having from 21 to 50 percent, preferably from 30 to 40 percent by weight, of oxyethylene groups, as long as the proportions of components such that the total content of oxyethylene groups is between 2 and 25 percent, preferably between 2 and 20 percent by weight of the mixture. It is generally preferred not to use any individual polyol initiated with TDA having an oxyethylene content greater than 50 percent, especially greater than 40 percent, in such mixtures, since this would tend to introduce a significant proportion of hydroxyl groups primary. The polyol or polyols initiated with TDA are conveniently prepared in a known manner, by adding ethylene oxide and another alkylene oxide (preferably propylene oxide) to the toluene diamine, under polymerization conditions. Suitable polymerization methods are described in DE 42 32 970 A1, in U.S. Patent No. 4,562,290 and U.S. Patent No. 4,209,609, all incorporated herein by way of this reference. In general, the polyether initiated with TDA is prepared by first reacting the TDA with ethylene oxide or with a mixture of OE / OP, after which it is further reacted with additional OP. These polymerizations can be catalyzed, if desired; but it is usually not necessary to catalyze OE polymerizations or OE / OP copolymerizations. Suitable polymerization temperatures are from 70 to 150 ° C. Suitable polymerization catalysts include all alkali metal hydroxides, alkaline earth metal hydroxides, so-called double metal cyanide catalysts, and tertiary amines. To produce a polyether initiated with TDA having from 2 to 20 percent OE internally polymerized, and a hydroxyl number from 300 to 600, it is polymerized from 0.18 to 3.4 moles of OE and from 3.1 to 8.1 moles of OP per mole of TDA . The TDA may be 2,3-TDA, 2,4-TDA, other isomers or mixtures of such isomers. The TDA preferably is 2,3-TDA or a mixture containing at least 50 percent, preferably at least 80 percent, more preferable, at least 90 percent, better still, at least 95 percent by weight, of 2,3-TDA, the rest being other isomers of TDA, such as the 2,6- and 2,4-TDA isomers, and / or impurities. The polyols initiated with TDA can be mixed with other polyols, provided that the polyol mixture has an average hydroxyl number of 300 to 600, and the polyol mixture has on average three or more hydroxyl groups per molecule. Such suitable polyols include polyether polyols having from 3 to 8 hydroxyl groups per molecule, and polyester polyols. The polyether polyols can be initiated with amine, such as those initiated with ethylenediamine, or can be initiated with poly (hydroxy) compounds, such as sugars (eg, sucrose), glycerin and trimethylolpropane. The polyether polyols initiated with sucrose / glycerin are particularly interesting. Polyester polyols are typically difunctional; therefore, preferably, they do not constitute more than 25 percent, especially 15 percent of the total weight of all the polyols. The polyisocyanate component includes a polyisocyanate compound or a mixture thereof, which has an average of two or more isocyanate groups per molecule, preferably an average of 2.5 to 4.0 isocyanate groups per molecule. The polyisocyanate compound can be aromatic, aliphatic or cycloaliphatic. Examples of suitable polyisocyanates are: 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,6-hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,4-cyclohexane diisocyanate, hexahydrotolylene diisocyanate. (all isomers), 1, 5-naphthylene diisocyanate, 2,4-1-methoxyphenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-biphenylene diisocyanate , 3,3'-dimethoxy-4,4'-diphenyl diisocyanate, 3,3'-dimethyldiphenylpropane-4,4'-diisocyanate, polymethylene and polyphenyl diisocyanates (commonly known as MDI). Polymeric MDIs are particularly suitable due to their high functionality, ease of obtaining, low volatile content and low cost. In addition to the above polyisocyanates, prepolymers and their quasi-(or semi-) prepolymers are useful. A combination of water and a physical blowing agent is used to form the foam. The water produces carbon dioxide by reacting with the polyisocyanate compound; for that reason, sufficient polyisocyanate compound must be provided to react with the water. 0.1 to 4 parts of water are provided per 100 parts by weight of the polyol mixture. A preferred amount of water is from 1.0 to 3.25 parts. A more preferred amount of water is 1.5 to 5 parts. An especially preferred amount is 1.4 to 2.25 parts. The physical blowing agent is one or more hydrofluorocarbons (HFC) having from 2 to 4 carbon atoms; ally us having 3 to 6 carbon atoms and / or cycloalkanes having 5 to 6 carbon atoms. Mixtures of these can be used. Thus, when an HFC or a mixture of HFCs is the main blowing agent, the HFC may contain one or more hydrocarbons. Conversely, when a hydrocarbon or mixture of hydrocarbons is the main blowing agent, the hydrocarbon may contain one or more HFCs. Among the hydrofluorocarbon blowing agents (HFC) are. HFC-125 (1,1,1,2,2-pentafluoroethane), HFC-134A (1,, 1,2-tetrafluoroethane, HFC-143 (1,1,2-trifluoroethane), HFC 143A (1, 1, 1-trifluoroethane), HFC-152 (1,1-difluoroethane), HFC-227ea (1, 1, 1, 2, 3, 3, 3-heptaf luoropropane), HFC-236ca (1, 1, 2,2, 3,3-hexafluoropropane), HFC 236fa (1,1,1,3,3,3-hexafluoroethane), HFC 245ca (1, 1, 2,2,3-pentafluoropentane), HFC 356mff (1,1,1, 4,4,4-hexafluorobutane) and HFC-365mfc (1,1,1,3,3-pentafluorobutane) They are of particular interest among hydrofluorocarbons: HFC 134A, HFC 245fa, HFC365mfc and mixtures thereof. Useful alkane and cycloalkane include: n-butane, isobutane, n-pentane, isopentane, n-hexane, isohexane, cyclopentane and cyclohexane Cyclopentane, n-pentane and isopentane are preferred among hydrocarbon blowing agents The physical blowing agent is used in such a quantity that, in combination with the carbon dioxide produced in the reaction of the water with the isocyanate, an One of a desired density. In the usual case, the desired density of the foam will be in the range of 20.01 to 96.06 g / L (1.25 to 6 pounds / cubic feet), preferably from 24.01 to 64.04 g / L (1.5 to 4 pounds / cubic feet) , especially from 25.61 to 36.82 g / L (1.6 to 2.3 pounds / cubic foot). In addition, the amount of physical blowing agent is preferably selected so that the physical blowing agent constitutes 40 to 90 molar percent, preferably 50 to 80 molar percent, especially 60 to 80 molar percent, of the combined number of moles of water and physical blowing agent, provided in the foam formulation. To satisfy these parameters, usually 15 to 40 are provided, more typically from 20 to 35 parts by weight of physical blowing agent per 100 parts of polyol blend. The foam formulation may also contain auxiliary additives that promote the formation of a stable, good quality foam. Said additives include, for example: catalysts, surfactants and pigments. Suitable catalysts include the well-known polyurethane catalysts, such as those described in column 6 of U.S. Patent No. 5,817,860, which is incorporated herein by way of this reference. It is preferred to use, in general, a mixture of at least one catalyst that promotes the reaction of the water with a polyisocyanate, and at least one other catalyst that promotes the reaction of the polyol or the polyols with the polyisocyanate. A catalyst that promotes the trimerization reaction of the isocyanates to form isocyanurate groups can also be used, and is preferred when the isocyanate index is greater than 1.2. Such catalysts include the salts and chelates of tin, zinc, bismuth, iron and mercury, as well as tertiary amine compounds. Organotin catalysts, such as stannous octoate, stannous oleate, stannic chloride, dimethyltin dilaurate and dibutyltin dilaurate are the preferred metal catalysts. Suitable tertiary amine catalysts include: triethylenediamine (commercially available as a 33 weight percent solution), trimethylamine, triethylamine, N-methylmorpholine, N-ethylmorpholine, N-co-morpholine, 1-methyl-4- dimethylamino ethyl piperazine, 3-methoxy-N-dimethylpropylamine, N, N-dimethyl-N ', N'-methylisopropyl-propylenediamine, N, N'-diethylamino-propylamine, N, N-dimethylbenzylamine, N, N- dimethylethanolamine, N, N-dimethylpiperazine, 1,4-diazobicyclo [2.2.2] octane, bis- (dimethylaminoethyl) ether, bis (2-dimethylaminoethyl) ether, morpholine, N, N-dimorpholine diethyl ether, N, N-dimethylcyclohexylamine, 4,4 '- (oxydi-2,1-ethanediyl) bis, and pentamethylenediamine. The catalyst is conveniently dissolved or dispersed in the component reactive with the isocyanate or in the isocyanate component. The amount is selected to provide a desired reaction rate. In most applications, it is desirable that there be sufficient catalyst to provide a gelling time (by the test described below) of 15-50 seconds, preferably 25-40 seconds, more preferably, 28-35 seconds. In most cases the foam formulation will include a surfactant. Suitable surfactants include well-known silicone surfactants, as well as non-ionic polyether surfactants. Silicone surfactants include commercially available polysiloxane / polyether copolymers, such as Tegostab (trademark of Goldschmidt Chemical Corp.), B-8462 and B-8404, Niax (trademark of GE Silicones), surfactants L-6900 and L-6910, and the surfactants DC-198 and DC-5043, obtainable from Dow Corning. The surfactant is used to stabilize the cellular structure of the foaming reaction mixture, until it hardens. Nonionic polyether surfactants include: block copolymers of ethylene oxide / propylene oxide and ethylene oxide / butylene oxide. It is less preferred to use anionic or cationic surfactants. Typically, the surfactant is used at levels of 0.5 to 4 parts, especially 1.5 to 3 parts, per 100 parts by weight of the polyol mixture. As with the catalyst, the surfactant may be incorporated in the isocyanate-reactive component or in the isocyanate component, or in both; but very typically it is incorporated in the component reactive with the isocyanate. Other optional components of the foam formulation include fillers, such as talcs, clays, silicas, calcium carbonates, graphites, glass, carbon black and plastic powders, such as ABS; fibers, such as glass or other ceramic fibers, carbon, metals or polymers, such as polyamide (ie, Kevlar), propylene, colorants, biocides and preservatives. The foam of the invention is prepared conveniently by mixing the polyol component and the isocyanate component in the presence of the blowing agents, under conditions such that the polyols and the polyisocyanate or the polyisocyanate reactions and cure; and the blowing agents simultaneously generate gases to expand the reaction mixture. It is usually not necessary to preheat the components or apply heat to the reaction mixture in order to obtain a good reaction and a good cure. However, if desired, heating can be used. The proportions of the components are advantageously selected to provide an isocyanate index (ratio of NCO groups to isocyanate-reactive groups, in polyols and water), of 0.7, preferably 0.9, more preferably, 0.98 to 3.0, preferably 1.5. , more preferable, to 1.25, especially, to 1.1. Since an important application for these foams is in thermal insulation applications, in the usual foam manufacturing processes, the foam formulation will be mixed and placed in a closed space, where thermal insulation is necessary. The formulation then reacts and expands to form the foam in situ. The walls that form the enclosed space can be heated, if desired, to promote healing and / or adhesion of the foam to the walls. The walls that define the closed space are usually held in place mechanically, using a restraining device or other apparatus, until the foam formulation has reacted sufficiently to be dimensionally stable and able to be demolded. In most thermal insulating applications it is convenient to use sufficient foam formulation to form a closed cell foam, of good quality, which cures in a short time to become dimensionally stable. This is often achieved by determining the minimum amount of foam formulation needed to just fill the enclosed space, and using a slightly larger amount, such as 5 to 20 percent more, especially 7 to 15 percent more formulation of foam, to fill the part and form the foam. This "excessive packing" helps to ensure that the enclosed space is completely filled and reduces the time that the formulation needs to be cured, in order to produce a foam that is dimensionally stable, enough to be "unmolded", releasing the walls that enclose it, of its mechanical restrictions. The demolding time is then determined by the time necessary for the foam to be sufficiently stable from the dimensional point of view, and conveniently is from 1 minute to less than 5 minutes, preferably from 2 to 3.5 minutes, especially from 2 minutes. 3 minutes. A common and current method for evaluating the ability to cure from a foam formulation, to a dimensionally stable state, is to measure the amount of expansion exhibited by the foam when it is demolded at a fixed time. A typical test is to mold a foam into a standard mold, commonly called a Brett mold, let it cure for three minutes (or another predetermined time) and then release the restrictions on the mold, so that any further expansion of the foam make the mold open. What the mold opens is a measure of the expansion of the foam subsequent to the demolding. In this test, the demoulding expansion is conveniently less than .2.54 mm (0.1"), preferably less than 1.27 mm (0.05"), still more preferable, 0.762 mm (0.03") or less. The cured foam preferably exhibits a factor k of less than 0.0533 (0.150), more preferably, less than 0.1736 (0.140), still more preferable, of 0.1674 (0.135) or less, especially 0.1636 cal-cm (cm2 x hr x ° C) (0.132 BTU-in /? ie2-hr- ° F). In some cases K factors of just 0.1550 (0.125), more typically, of just 0.1587 cal-cm (cm2 x hr x ° C) (0.128 BTU-in / ft-hr- ° F), can be obtained by optimization . The foam factor k will depend on several factors, including the selection of the agent or blowing agents, the size of the cell and the reactivity of the formulation (expressed as the gel time). Examples of specific applications for the foam formulation of the invention include thermal insulation applications, such as in chillers, freezers, refrigerators, ceilings, walls and floors. The foam formulation can be used to create thermal insulation panels that may or may not contain façade sheets. The foam formulation of the invention can also be used in free lift applications. The following examples are given to illustrate the invention, but are not intended to limit its scope. All parts and percentages are by weight, unless otherwise indicated. The following polyols are used in the following examples and in the comparative examples: Polyol A. A polyol initiated with TDA, formed by first reacting 54 parts of o-TDA with a mixture of 17.5 parts of OE and 79.6 parts of OP at 125 ° C for four hours. Then 2.66 parts of dimethylethylamine are added and 65.7 parts of OP are fed at 125 ° C. After the reactor pressure becomes constant at 3.7 bars, 1.33 parts of additional dimethylethylamine is added and the mixture is digested overnight at 125 ° C. The residual OP is removed by a purge with nitrogen. The resulting polyol contains 8 percent oxyethylene groups and has a hydroxyl number of about 456. Polyol B. A polyol initiated with TDA prepared in the general manner described for polyol A, except that the proportions of OE / OP are changed to producing a polyol containing 17 percent oxyethylene groups and having an approximate hydroxyl number of 430. Polyol C. A polyol initiated with TDA, containing 35 percent oxyethylene groups and having an approximate hydroxyl number of 390. Polyol D A polyol of propylene oxide, initiated with TDA, having no oxyethylene groups and having a hydroxyl number of 430. Polyol E. A polyol of propylene oxide with hydroxyl number of 360, initiated from of a sucrose / glycerin mixture. Polyol F. A difunctional, aromatic polyester polyol having a hydroxyl number of about 300. Polyol G. A trifunctional poly (propylene oxide) polyol, having a hydroxyl number of 170. Polyol H. A polyol of polyol. ! (propylene oxide) initiated with ethylene diamine, tetrafunctional, having a hydroxyl number of 640.

EXAMPLES 1 TO 3 AND COMPARATIVE EXAMPLES C1 AND C2 Rigid polyurethane foam is prepared in Examples 1 to 3 and in Comparative Examples C1 and C2, from the foam formulations indicated in Table 1.

TABLE 1 1 Mixture of pentamethylethylenediamine (Polycat ™ 5, from Air Products and Chemicals), dimethylcyclohexylamine (Polycat ™ 8, from Air Products and Chemicals, and the potassium salt of dimethylcyclohexylamine, in diethylene glycol (Polycat ™ 46, from Air Products and Chemicals). 2 Miax ™ L-6900, silicone surfactant, from GE Silicones.

Polymeric IDI with an approximate functionality of 2.7 and an isocyanate equivalent weight of 134. 4 Weight proportion of isocyanate component to component reactive with the isocyanate. The foams are prepared and tested as follows. The density at free elevation and the gel time are determined by mixing 600-800 grams of the foam formulation, pouring it into a plastic bag and allowing the foam to expand without restriction. The gelation time is determined from the time the reactive components are mixed with the isocyanate and the isocyanate, until threads are formed, when the mixture is touched with a wooden tongued tongue and removed. The free elevation density is measured in a central sample according to ASTM-D-1622, and the k-factor, the minimum filling density, the compressive strength and the demold expansion of a foam made in a Brett mold standard two-piece, hinged, 5 x 20 x 200 cm. The hinge is along one side of 200 cm. The minimum fill density is measured by sufficient foaming of the foam formulation within the mold to fill approximately 95 percent of the mold volume. The weight of the foam formulation, divided by the volume of the foam, is given as the minimum filling density. The k-factor, the compressive strength and the demold expansion, of samples made in the Brett mold, with an excess of 10 percent packing, are measured and are measured according to ASTM C-518 and D-1621, respectively. The demold expansion is measured by releasing the pressure in a Brett mold with a 10% excess packing, three minutes after the reactive components are mixed with the isocyanate and isocyanate, and the amount of mold opening on the side is measured. 200 cm opposite the hinge. The results are indicated in table 2.

TABLE 2 The comparative sample C1 is illustrative of the good quality foam that can be obtained using a fully OP polyol, initiated with TDA. The foam has an excellent k-factor of 0.0189 W m "1 K" 1 (0.131) and exhibits very minute expansion by demolding. Generally, the k-factor tends to improve with a reduced gelling time (all other factors remaining the same) at a rate of an improvement of 0.001 units for every three seconds of reduction in gelation time. By increasing the catalyst levels slightly to reduce the gel time for example C1, a k-factor of 0.0187 W m "1 K" 1 (0.130 BTU-in / ft2-hr- ° F) can be expected, with minimal effect about the other properties. However, as is well known, fully OP polyols, initiated with TDA, are too viscous to be processed consistently and reliably in most commercial foaming equipment. The comparative sample C2 illustrates how the foam properties deteriorate, mainly the k factor and the demold expansion, when the fully OP polyol, initiated with TDA, is replaced with a polyol initiated with TDA having a high oxyethylene content. The k factor suffers significantly even when the increased gelling time is taken into account. The demolding expansion increases substantially. Example 1 illustrates how the use of an 8 percent OE polyol, initiated with TDA, produces a foam having a factor k comparable to that of comparative sample C1, with minimally increased demoulding expansion, commercially acceptable. As with comparative sample C1, it would be expected that the optimization of the catalyst packing, to bring the gelling time to 30 seconds, would decrease the k-factor to 0.129 or 0.130. However, contrary to the all-OP polio, initiated with TDA, used in comparative sample C1, this formulation has low viscosity and is processed easily and reproducibly. The proportion of blowing agent HFC-245 is higher in Examples 1 to 3 than in any of the comparative examples. It is expected that a change in the molar ratio of HFC-245 from 60 percent to 70 percent will increase the k factor by about 0.0013 units. A change in the molar ratio of HFC-245 from 60 percent to 80 percent would be expected to increase the k-factor by about 0.0026 units. Examples 2 and 3 illustrate that the low k-factors and low demold expansions provided by the invention can be achieved when a portion of the polyol initiated with TDA is replaced with other non-aromatic polyols that do not contain amine. Example 8 illustrates that this is the case when up to 10 weight percent of the polyol mixture is a difunctional polyol. Some deterioration is observed in the demold expansion in Example 3, but in general this value is acceptable, and is much lower than that of comparative sample C2.

EXAMPLES 4 TO 7 Examples 4 to 7 of rigid polyurethane foam are prepared and evaluated as described with respect to Examples 1 to 3, using foam formulations as indicated in Table 3.

TABLE 3 1-4 see notes 1-4 of table 1. The resulting foams are made and evaluated as described in example 1, with the results that are indicated in table 4.

TABLE 4 Examples 4 to 7 show that a polyol initiated with TDA containing a slightly higher level of oxyethylene groups, still provides a convenient combination of low factor k and low expansion by demolding, in particular when compared to example C2. The comparison between examples 4 and 7 is interesting. A mixture of two polyols initiated with TDA is used in Example 7: one containing 35 percent oxyethylene groups, and the other containing no oxyethylene groups. The mixture contains about 17 percent oxyethylene groups, similar to the content of the polyol used in Example 4. Except for some loss in compressive strength, the mixture of the polyols initiated with TDA performs very similarly to the single polyol initiated with TDA used in example 4. However, polyol D is viscous and must be mixed with polyol C before it can be easily used in commercial foam manufacturing equipment. The additional mixing step increases the costs and makes this option less preferred.

EXAMPLES 8 AND 9 AND COMPARATIVE SAMPLES C3 AND C4 Examples 8 and 9 of rigid polyurethane foam and comparative samples C3 and C4 are prepared and evaluated as described with respect to examples 1 to 3, using foam formulations as indicated in table 5.

TABLE 5 TABLE 5 (continued) 1'4 See notes 1-4, table 1. The resulting foams are prepared and evaluated as described in example 1, with the results indicated in table 6 below. TABLE 6 Examples 8 and 9 demonstrate the use of the polyol initiated with TDA, with blowing agent packages including HFC-134a. These represent non-optimized systems. It is expected that the optimization reduces the minimum filling density and the values of expansion by demolding of Example 8 and the value of expansion by demolding of Example 9. Despite the non-optimized formulation, very low k-factors are obtained. Comparative samples have significantly higher k factors, even after adjusting for differences in blowing agent composition and gel times.

EXAMPLE 10 AND COMPARATIVE SAMPLE C5 The rigid polyurethane foam of the example is prepared and comparative sample C5, and evaluated as described with respect to Examples 1 to 3, using foam formulations that are indicated in Table 7.

TABLE 7 1"4 See notes 1-4, table 1. The resulting foams are prepared and evaluated as described in example 1, with the results indicated in table 8 below.

TABLE 8 Example 10 illustrates the use of the low OE polyols, initiated with TDA, as a minor component of the polyol mixture and in a co-blown formulation with cyclopentane / water. Even when the TDA-initiated polyether of the invention is used as a minor component, a significant improvement in demold expansion is seen.

EXAMPLE 11 The rigid polyurethane foam of Example 11 is prepared, and evaluated as described in relation to Examples 1-2, using the foam formulation which is indicated in Table 9. This example uses 35 weight percent polyol or -TDA with 8 percent OE and an equal amount of polyol or-TDA of 35 percent by weight of EO, for a mixture of polyol or-TDA with 22 percent OE comprising 70 percent of the total polyols that are present.

TABLE 9 1-4 See notes 1-4, table 1 The resulting foam is formed and evaluated as described in Example 1, with the results indicated in Table 10 below.

TABLE 10 Example 11 demonstrates that using a polyol with higher OE content, the demold expansion is larger than that observed for examples 1-3, but still within commercial limits.

Claims (22)

1. - A method for forming a polyurethane foam, characterized in that it comprises: "(1) forming a reaction mixture by mixing, under reaction conditions: (a) an isocyanate-reactive component, which contains a polyol or a mixture thereof, which they have an average hydroxyl number of 300 to 600, and an average of at least 3 hydroxyl groups per molecule, with (b) an isocyanate component containing a polyisocyanate that is reactive with the polyol or with the mixture thereof in the presence of an effective amount of physical blowing agent, selected from the group consisting of hydrofluorocarbons having from 2 to 4 carbon atoms and from 0.1 to 4 parts by weight of water per 100 parts by weight of the polyol or mixture thereof; 2) subjecting the reaction mixture to such conditions, that it reacts, expands and cures within a closed space, to form a rigid polyurethane foam within the enclosed space, where at least 10 weight percent of the po Liol or the mixture thereof is one or more polyethers initiated with toluene diamine, which contain the hydroxyl group; where the polyether or the polyethers initiated with toluene diamine have an average hydroxyl number of from 300 to 600, and in addition, where the oxyethylene groups (-CH2-CH2-0-) constitute from 2 to 25 percent of the total weight of / the polyether (s) initiated (s) with toluene diamine.

2. - The method according to claim 1, further characterized in that the physical blowing agent is selected from HFC 134A, HFC 245fa, HFC 365mfc, and mixtures thereof.

3. A method for forming a polyurethane foam, characterized in that it comprises: (1) forming a reaction mixture by mixing, under reaction conditions: (a) an isocyanate-reactive component containing a polyol or a mixture thereof, which it has an average hydroxyl number of 300 to 600 and an average of at least three hydroxyl groups per molecule; with (b) an isocyanate component containing a polyisocyanate that is reactive with the polyol or with the mixture thereof; in the presence of an effective amount of physical blowing agent, selected from the group consisting of alkanes having from 3 to 6 carbon atoms and cycloalkanes having 5-6 carbon atoms, and from 0.1 to 4 parts by weight of water per 100 parts by weight of the polyol or the mixture thereof; and (2) subjecting the reaction mixture to conditions such that it reacts, expands and cures within a closed space to form a rigid polyurethane foam within the enclosed space; wherein at least 10 weight percent of the polyol or mixture thereof is one or more polyethers initiated with toluene diamine, which contain the hydroxyl group; where the polyether (s) initiated with toluene diamine has (n) an average hydroxyl number of 300 to 600; and further, where the oxyethylene groups (-CH2-CH2-O-) constitute from 2 to 25 percent of the total weight of the polyether (s) initiated with toluene diamine.

4. The method according to claim 1 or 3, further characterized in that the polyether or polyethers initiated with toluene diamine have an average oxyethylene group content of 3 to 20 weight percent.

5. The method according to claim 4, further characterized in that the toluene diamine is the 2-3 isomer by at least 50 weight percent thereof.

6. The method according to claim 1 or 3, further characterized in that the polyether or polyethers initiated with toluene diamine constitute at least 50 percent by weight of the polyol or mixture thereof.

7. The method according to claim 6, further characterized in that the polyether or polyethers initiated with toluene diamine have an average oxyethylene group content of 6 to 15 weight percent.

8. The method according to claim 7, further characterized in that the polyether or polyethers initiated with toluene diamine constitute at least 80 weight percent of the polyol or mixture thereof.

9. The method according to claim 3, further characterized in that the physical blowing agent is selected from alkanes having from 3 to 6 carbon atoms and cycloalkanes having 5-6 carbon atoms, or a mixture of two or more said blowing agents.

10. The method according to claim 1 or 3, further characterized in that the reactive component is mixed with the isocyanate and the isocyanate component in the presence of a surfactant and a catalyst.

11. The method according to claim 1 or 3, further characterized in that the closed space is a wall of a freezer, a refrigerator or a cooler.

12. An isocyanate-reactive composition, characterized in that it comprises: (a) an isocyanate-reactive component containing a polyol or a mixture thereof, having an average hydroxyl number of 300 to 600 and an average of at least three groups hydroxyl per molecule; (b) an effective amount of a physical blowing agent, selected from the group consisting of hydrofluorocarbons having from 2 to 4 carbon atoms; and (c) from 0.1 to 4 parts by weight of water, per 100 parts by weight of the polyol or mixture thereof; wherein at least 10 weight percent of the polyol or mixture thereof is one or more polyethers initiated with toluene diamine, which contain the hydroxyl group; the polyether or polyethers initiated with toluene diamine have an average hydroxyl number of 300 to 600, and the oxyethylene groups constitute 2 to 25 percent of the total weight of the polyether or polyethers initialed with toluene diamine. .

13. The composition according to claim 12, further characterized in that the physical blowing agent is selected from HFC 134A, HFC 245fa, HFC 365mfc and mixtures thereof.

14. An isocyanate-reactive composition, characterized comprising: (a) an isocyanate-reactive component containing a polyol or a mixture thereof, having an average hydroxyl number of 300 to 600 and an average of minus three hydroxyl groups per molecule; (b) an effective amount of a physical blowing agent, selected from the group consisting of alkanes having from 3 to 6 carbon atoms and cycloalkanes having 5-6 carbon atoms, or a mixture of any two or more of the agents previous physical blowers; and (c) from 0.1 to 4 parts by weight of water per 100 parts by weight of the polyol or mixture thereof; wherein at least 10 weight percent of the polyol or mixture thereof is one or more polyethers initiated with toluene diamine containing the hydroxyl group; and the polyether or polyethers initiated with toluene diamine have an average hydroxyl number of from 300 to 600, and the oxyethylene groups constitute from 2 to 25 percent of the total weight of the polyether or polyethers initiated with toluene diamine.

15. The composition according to claim 12 or 14, further characterized in that the polyether or polyether (s) with toluene diamine have an average oxyethylene group content of 3 to 20 weight percent.

16. The composition according to claim 15, further characterized in that the toluene diamine is at least 50 weight percent, the isomer 2-3.

17. The composition according to claim 16, further characterized in that the polyether or the polyethers initiated with toluene diamine constitute at least 50 weight percent of the polyol or mixture thereof.

18.- The composition in accordance with the claim 17, further characterized in that the polyether or polyethers initiated with toluene diamine have an average oxyethylene group content of 6 to 12 weight percent.

19.- The composition in accordance with the claim 18, further characterized in that the polyether or polyethers initiated with toluene diamine constitute at least 80 weight percent of the polyol or mixture thereof.

20. The composition according to claim 14, further characterized in that the physical blowing agent is selected from alkanes having from 3 to 6 carbon atoms, and cycloalkanes having 5-6 carbon atoms, or a mixture of two. or more of said blowing agents.

21. - The composition according to claim 12 or 14, further characterized in that the isocyanate-reactive component and the isocyanate component are mixed in the presence of a surfactant and a catalyst.

22. A method for forming a polyurethane foam, characterized in that it comprises: (1) forming a reaction mixture, by mixing, under reaction conditions: (a) an isocyanate-reactive component containing a polyol or a mixture thereof, having an average hydroxyl number of 300 to 600, and an average of at least three hydroxyl groups per molecule; with (b) an isocyanate component containing a polyisocyanate that is reactive with the polyol or with the mixture thereof; in the presence of an effective amount of the physical blowing agent selected from the group consisting of hydrofluorocarbons having from 2 to 4 carbon atoms, alkanes having from 3 to 6 carbon atoms and cycloalkanes having 5-6 carbon atoms, or mixing of any two or more of the above physical blowing agents, and from 0.1 to 4 parts by weight per 100 parts by weight of the polyol or the mixture thereof; and (2) subjecting the reaction mixture to conditions such that it reacts, expands and cures within a confined space, to form a rigid polyurethane foam within the enclosed space; wherein at least 10 weight percent of the polyol or mixture thereof is one or more polyethers initiated with toluene diamine, which contain the hydroxyl group; where the polyether or the polyethers initiated with toluene diamine have an average hydroxyl number from 300 to 600, and in addition, where the oxyethylene groups (-CH2-CH2-O-) constitute from 2 to 25 percent of the total weight of the polyether or the polyethers initiated with toluene diamine.