MXPA96002357A - Polyurethane elastomeros that exhibit improved properties of decommunity, resistance in raw and absorption of water, and polyols that do not present turbidity and are adequate for the preparation of estoselastome - Google Patents

Abstract

Polyurethane elastomers are prepared which exhibit improved green strength while maintaining short stripping times, the preparation is made from ultra low unsaturation polyoxypropylene polyols containing up to 20 weight percent of internal and random oxyethylene entities. The elastomers absorb less than 10 weight percent water at 0 ° C. The polyoxyethylene polyols containing the internal polyoxyethylene entity can be used to prepare polyols of ultra low unsaturation polyoxyethylene which are free of turbidity and which can be used to prepare turbidity-free 4,4'-MDI prepolymers. Multi-dispersed mixtures of polyoxypropylene polyols, which contain monodisperse oxyethylene internal entities with ultra-low unsaturation, provide even more improvements in elastomer processing

Description

POLYURETHANE ELASTOMERS THAT EXHIBIT IMPROVED PROPERTIES OF DECOMMUNITY, RESISTANCE IN RAW AND ABSORPTION OF WATER, AND POLYOLS THAT DO NOT PRESENT TURBIDITY AND ARE SUITABLE FOR THE PREPARATION OF THESE ELASTOMERS TECHNICAL FIELD This invention relates to polyurethane elastomers and polyoxypropylene / polyoxyethylene polyols of ultralow unsaturation and which do not develop turbidity and are suitable for the preparation of these elastomers. More particularly, the invention relates to polyurethane elastomers having improved demold and green strength properties while exhibiting low water absorption, and in addition, to polyoxypropylene polyols having internal and random oxyethylene entities, and they are suitable for preparing these elastomers. Surprisingly, the random oxyethylene entities containing polyoxypropylene polyoxyethylene-capped polyols do not develop turbidity during storage, nor do the isocyanate terminated prepolymers made of 4,4'-methylenediphenylene isocyanate which are prepared from these.

PREVIOUS TECHNIQUE The processing characteristics are critical l'l 1 ') 1 / 9í > MX to determine the commercial viability of polyurethane elastomers. Examples of these processing characteristics are: the shelf life in the container, the gelling time, the demolding time and the green strength, among others. A commercially acceptable container life is necessary to allow, when necessary, a sufficient working time for the mixing and degassing of the components forming the reactive polyurethane. The gelling time is critical since it allows the complete filling of the molds before the gelation occurs, particularly when using large and complex molds, and the demolding time is important to maximize the production of parts. A too long demoulding time requires a greater number of molds, which are relatively expensive, for the manufacture of a given part. Release time is especially critical for glycol-extended elastomers that tend to cure slowly. These requirements usually rival. For example, a decrease in the level of the catalyst will in general give a longer pot life and increase the gelling time, but will very often give an unsatisfactory demoulding time, and vice versa. Crude resistance is also important. The Pl lr __ / 9ßMX green strength is a partially subjective measure of the durability of a polyurethane part immediately after demolding. The characteristics of the polyurethane-forming reaction are such that the complete strength of the polyurethane parts does not develop for a considerable time after casting. However, the "raw" or partially cured piece must be demolded within a reasonable time. The polyurethane pieces typically show two types of "poor" green strength. One of these types is that in which the piece is gelled and rigid but is brittle and can easily tear. Those of ordinary skill in this field of polyurethane elastomers refer to this type of poor raw strength as "chemistry" in relation to its consistency similar to that of cheese. The other type of "poor" raw resistance is when the piece is soft and foldable, and permanently distorts during the demoulding process. In contrast, the pieces that when demolding show durability and that can be twisted or bent, without permanent damage, are said to have an "excellent" raw resistance. While demold time limits production, poor raw strength increases the proportion of wasted material. Several methods to increase the green strength and decrease the demoulding time have been examined.

I'l 1 .1 / I.MX For example, increasing the level of catalyst has a desirable influence on these properties. However, as already mentioned, the higher levels of catalyst also decrease the pot life and the gelling time. In addition, when microcellular elastomers are going to be produced, some of these catalysts increase the reaction between the isocyanate and the water to a greater degree than the reaction between the isocyanate and the polyol, and thus the processability can be affected. It is well known in the art that polyurea and polyurethane / urea elastomers are much easier to process than urethane elastomers. The polyurea and polyurethane / urea elastomers are prepared using amine terminated polyols and / or diamine chain extenders. The most common urethane / urea elastomeric systems use a toluene diisocyanate prepolymer that is reacted with the diamine extender, methylene-bis- (2-chloroaniline), better known as MOCO or MBOCA. This system is known to have a long shelf-life in the vessel (10 to 20 minutes) with commercially acceptable demoulding times of less than 60 minutes and excellent green strength. In addition to this, there is minimal sensitivity to changes in processing conditions in this system. However, some of the physical properties of the elastomers which contain urea bonds are lower in comparison to all urethane elastomers (ie, in softness, tear strength, resilience and strength). hydrolysis). Water absorption is critical in many applications of polyurethane elastomers. For example, polyurethane elastomer seals that are exposed to aqueous environments may experience fairly degraded physical properties due to plasticization by water effect or by interruption of the hydrogen bonds between the polar groups of the elastomeric polymer. The elastomers used in highway expansion belts can swell and extrude from the pavement and require frequent replacement. Shoe soles, particularly those of cellular and microcell type, typical for athletic footwear, can absorb considerable amounts of water, particularly at low temperatures. For these reasons, when an exposure to water is contemplated, elastomers made from homopolyxypropylene polyols or polytetramethylene ether glycols (PTMEG) have been used. In these applications the water absorption is only about 2% by weight at 0 ° C and lower at higher temperatures. However, PETMEG used in PTMEG-based elastomers is a starting material with a much higher cost IM /'lí.MX, and elastomers based on homopolioxypropylene polyols generally have longer demold times and lower optimum raw strength. The addition of larger amounts of catalyst, for example of tin octoate, can decrease the demolding time and increase the green strength, but at the expense of having a shorter pot life and shorter gelling times, as already stated. he argued. In U.S. Patent No. 5,106,874, the use of polyoxypropylene polyols having unsaturations in the range of 0.02 meq / g of polyol to 0.04 meq / g of polyol is said to have shorter demolding times. However, as shown in our United States Coherent Patent Application, filed on the same date as this one, even at 0.010 meq / g unsaturations, the release time of the elastomers extended with glycol is quite long, and it can be improved. only through the use of polyoxypropylene polyols having exceptionally low unsaturation in the range of 0.007 meq / g. These extremely low unsaturation polyols are preferably prepared by the use of an essentially amorphous catalyst of dimethyl cyanide • tertiary butyl alcohol (DMC »TBA). With these polyols it is possible to have a greater than double improvement in the demolding time, however the crude resistance is still not optimal.

P1151 / 96 X Polyoxypropylene polyols having an oxyethylene cap of 10 to 40 percent are known to decrease the stripping time in polyurethane elastomers, sometimes sacrificing pot life and gel time. The improvement in reactivity is due to the primary hydroxyl termination of these polyols. However, the elastomers prepared from these polyols are notoriously sensitive to water, sometimes adsorb 200 weight percent water at lower temperatures. In U.S. Patent 5,106,874 the use of polyoxyethylene-capped polyoxypropylene polyols having low unsaturation, ie from 0.02 to 0.04 meq / g is said to reduce the amount of oxyethylene cap required to provide the required primary hydroxyl content and thus decrease the sensitivity to water. However, water absorption was not measured. In addition, the exemplified systems are all rigid, are expanded polyurethane elastomers with diamine / urea and do not refer to polyurethane elastomers. A similar disclosure in relation to polyols having low unsaturation but high degree of oxyethylene cap can be found in U.S. Patent 5,185,420. Polyoxypropylene polyols, either homopolymers or copolymers with other alkylene oxides, are generally prepared by basic catalytic oxyalkylation Pl 151 / 6MX of propylene oxide on a suitable water initiator molecule. During polymerization, the competition rearrangement of propylene oxide in allyl alcohol, as discussed in Block and Graft Polymerization. Vol. 2 Ceresa, Ed. John Wiley & Sons, pp. 17-21, introduces monofunctional species at an increasing rate as oxypropylation proceeds. The unsaturation, measured with the ASTM method D2849-69, generally corresponds to the amount of the monofunctional species present, ie polyoxypropylene monols. At equivalent weights of 2000, the mole percent of the monol can be so high that it ranges from 45 to 50 molar or more, thus creating a practical upper limit for the molecular weight of the polyoxypropylene polyol. It has been found that the use of lower temperatures and lower levels of catalyst reduces the level of unsaturation, but only marginally, and at the expense of greatly increasing the processing time. The use of special catalysts, for example alkaline earth metal hydroxides and combinations of metal naphthenates and tertiary amines, has been used to decrease the unsaturation. However, these alternative catalysts only give marginal improvements in the unsaturation content in the range of 0.02 to 0.04 meq / g from the normal levels of 0.06 to 1.0 meq / g characteristic of basic catalysis. A significant improvement in content has been achieved P1151 / 9bMX of monol of the polyoxypropylene polyols using "double glime" metal cyanide complex catalysts, for example the non-stoichiometric catalysts of zinc glyoxal hexacyanocobaltate disclosed in U.S. Patent 5,158,922. By using these catalysts, polyoxypropylene polyols of a molecular weight much greater than those previously prepared could be prepared, for example, 10,000 Da polyoxypropylene triols with unsaturations of 0.017 meq / g, J.W. Reish et al., "Polyurethane Sealants and Cast Elastomers With Superior Physical Properties", 33RD ANNUAL POLYURETHANE MARKETING CONFERENCE, September 30 - October 3, 1990 pp. 368-374. Many of the patents have been directed to the use of higher molecular weight polyols to prepare polyurethanes. In these cases, it is said that the resulting improvements relate only to the ability to provide polyols of higher molecular weights with useful functionality, or additionally, with a lower content of monol, it is believed that the monol reacts as a "chain jammer" during the polyurethane addition polymerization. Illustrative examples of these patents are U.S. Patent 5,124,425 (sealants that cure at room temperature from high molecular weight polyols having less than 0.07 meq / g unsaturation); United States Patent no. 5,100,997 Pl_ 51 / 96MX (extended polyurethane elastomers with diamine / urea from high molecular weight polyols having less than 0. 06 meq / g); United States Patent 5,116,931 (thermoset elastomers from polyols catalyzed with dimethyl cyanide having less than 0.04 meq / g); and U.S. Patent No. 4,239,879 (elastomers based on polyols of higher equivalent weight). However, none of these patents addresses the processing characteristics that are of exceptional importance in the elastomer molding industry. C.P. Smith et al., In their work "Thermoplastic Polyurethane Elastomers Made from High Molecular Weight Poly-L ™ Polyols", POLYURETHANES WORLD CONGRESS 1991, September 24-26, 1991, pp. 313-318, exposes thermoplastic elastomers (TPU) prepared from polyoxypropylene diols topped with polyoxyethylene, with unsaturation in the range of 0.014 to 0.018 meq / g. The polyols used were prepared using dimetic cyanide • glime catalysts, and the elastomers showed an increase in physical properties compared to the elastomers prepared from diols catalyzed in conventional manner with 0.08 meq / g unsaturation. The processability was not discussed. It has been found that polyols of low unsaturation sometimes produce polyurethanes with anomalous properties. For example, the substitution of a P1151 / 96MX molecular weight triol of 10,000 Da catalyzed with DMC * glime by a conventional catalyzed triol of 6000 Da molecular weight, produced elastomer with a higher Shore A hardness where a softer elastomer would be expected, while substitution of a triol with molecular weight of 6000 Da and catalyzed with DMC'glime by a conventional triol of 6000 Da of molecular weight did not increase the hardness. However, elastomers extended with butanediol prepared from the polyols catalyzed with DMC * glime exhibited demold times of 150 minutes or more, which are not commercially acceptable in elastomer molding applications. In copending US Application No. 08 / 152,614 which is incorporated herein by reference, novel and complex catalysts of dimetic cyanide and terbutanol prepared by the intimate mixing of the catalyst reagents are exposed. These catalysts lack the crystallinity of the DMC'glime catalysts observed in X-ray diffraction studies, and also exhibit an activity greater than three to ten times in the polymerization of propylene oxide. It is especially surprising that the unsaturation decreases to an extremely low and unprecedented value by the use of these catalysts, with measured unsaturations ranging from 0.003 meq / g to 0.007 meq / g, and which are achieved routinely. P1151 / 96MX While the measurable unsaturation implies a finite but exceptionally low monol content, it is especially surprising that the analysis of the product polyols by gel permeation chromatography showed no detectable low molecular weight fractions. The polyols are essentially monodisperse. The almost total absence of any low molecular weight monol species makes the polyols have a different class of ultra-low unsaturations compared to those prepared with DMC * glime catalysts. The preparation of polyoxypropylene polyols topped with polyoxyethylene using dimethalic cyanide catalysts has so far proved unsuccessful. If the polymerization in a polyoxypropylene polyol catalyzed with dimethyl cyanide is attempted without changing the dimetic cyanide catalyst with a conventional basic catalyst, a complex mixture of top-finished polyoxypropylene polyols and unfinished polyoxypropylene polyols is obtained. Although it is not desired to be limited to a particular theory, it is believed that oxethylation occurs at an essentially higher rate than the catalyst / substrate transfer, for these cases. However, even when the polyoxypropylene polyols topped with polyoxyethylene obtained from the P1151 / 96MX conventional basic catalysis oxyalkylation of the polyoxypropylene polyols catalyzed by dimethyl cyanide unfortunately generates turbidity during storage, which is generally undesirable. However, the isocyanate-terminated prepolymers prepared from these polyols and the excess 4,4'-methylenediphenyl diisocyanate (4,4'-MDI) also develop turbidity, even if it is a crystalline 4,4'-MDI . While the effect of polyol turbidity on polymers prepared from these polyols can be difficult to quantify, the MDI crystals in the MID prepolymers can settle and thus artificially create a prepolymer with an NCO content that varies with time, the temperature and the agitation in the storage tank.

OBJECTS OF THE INVENTION It is an object of the present invention to provide polyurethane elastomers having improved demolding and green strength properties. It is a further object of the present invention to provide polyurethane elastomers with low water absorption while maintaining processing parameters that are commercially feasible. Still an additional object of this P1151 / 96MX invention is to provide polyoxypropylene polyols with ultra low unsaturation, topped with polyoxyethylene and which are free of turbidity. Still another object of the present invention is to provide 4,4'-MDI prepolymers free of precipitates and polyoxypropylene / polyoxyethylene polyols of ultralow unsaturation.

SUMMARY OF THE INVENTION It has surprisingly been found that polyurethane elastomers having a short stripping time and improved green strength properties can be prepared using ultra low unsaturation polyoxypropylene polyols having from 1 to about 20 weight percent of internal entities of oxyethylene. The elastomers prepared in this manner exhibit surprisingly low water absorption. It has also surprisingly been found that a further improvement in the green strength and demold time is possible by using polyol blends having a multimodal distribution in molecular weight together with an ultra-low unsaturation, and that these same polyols can be used to prepare, based on the same, both polyols topped with turbidity-free polyoxyethylene and 4.4-MDI prepolymers free of precipitates. Pl 1? L / .bMX BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a bar graph of water absorption at 0 ° C, 23 ° C and 50 ° C of a series of elastomers prepared from polyoxypropylene polyols having ultralow unsaturation (< 0.007 meq / g) containing 0% to 40% by weight of internal oxyethylene entities; Figure 2 is a graph of the resilience that is created over time for polyurethane elastomers prepared from 4000 Da polyols with ultra low unsaturation: a monodisperse polyoxypropylene homopolymer diol, - and a monodisperse polyoxypropylene diol containing % by weight of internal oxyethylene entities; and Figure 3 is a plot of hardness generated over time for the same elastomers as those of Figure 2.

DESCRIPTION OF THE PREFERRED MODALITIES The polyurethane elastomers of the present invention are prepared by reacting a di or polyisocyanate, preferably a diisocyanate, with a polyoxyalkylene polyether polyol mixture by any of the techniques of: prepolymer formation, formation in a single operation, or others, using the diols as chain extenders. While the process to prepare elastomers from Pl 151 / 96MX polyurethane and the starting materials that have been used in the past are known to experts in this field, reference will be made to the following materials in order to establish basic issues. The term "polyurethane" means a polymer whose structure contains predominantly urethane bonds between repeating units. These bonds are formed by the addition reaction between an organic isocyanate group R- [-NCO] and an organic hydroxyl group [HO-] R. In order to form a polymer, the compounds containing the hydroxyl group and the organic isocyanate must be at least difunctional. However, according to what is understood in modern times, the term "polyurethane" is not limited to polymers containing only urethane linkages, but includes polymers containing minor amounts of allophanate, biuret, carbodiimide, oxazolinyl, isocyanurate, uretidinedione, and urea bonds in addition to those of urethane. The isocyanate reactions leading to these types of bonds are summarized in POLYURETHANE HANDBOOK, Guter Oertel, Ed., Hanser Publishers, Munich, ® 1985, Chapter 2, page 7-41; and in POLYURETHANES: CHEMISTRY AND TECHNOLOGY, J.H. Saunders and K.C. Frisch, Interscience P1151 / 96MX Publishers, New York, 1963, Chapter III, pages 63-118. The reaction for the formation of urethane in general is made with a catalyst. Useful catalysts are well known to those skilled in the art and many examples can be found in POLYURETHANE HANDBOOK, Chapter 3, section 3.4.1 pages 90-95, and in POLYURETHANES: CHEMISTRY AND TECHNOLOGY, in Chapter IV, pages 129-217. The most commonly used catalysts are tertiary amines and organotin compounds, particularly dibutyltin diacetate and dibutyltin dilaurate. Combinations of the catalysts are also often useful. In the preparation of polyurethanes, the isocyanate is reacted with the active hydrogen-containing compound (s) at a ratio of isocyanate to active hydrogen ranging from 0.5 to 1 to 10 to 1. The "index" of the composition is defined as the ratio of -NCO / active hydrogen multiplied by 100. While the extremely broad range described above can be used, most polyurethane processes have rates ranging from 70 to approximately 120 or 130, preferably from 95 to about 110, and more preferably between about 100 to 105. In the case of polyurethanes which also contain considerable amounts of isocyanurate groups, the indexes exceed 200 and preferably PU51 / 96MX greater than 300 can be used together with a trimerization catalyst in addition to the useful polyurethane catalysts. To calculate the amount of active hydrogens present, in general, all compounds containing active hydrogen that are not undissolved solids are taken into account. In this way, the total includes polyols, chain extenders, functional plasticizers, etc. The hydroxyl group-containing compounds (polyols) which are useful in the preparation of polyurethanes are described in POLYURETHANE HANDBOOK, Chapter 3, Section 3.1, pages 42-61; and in POLYURETHANES: CHEMIST'RY AND TECHNOLOGY, Chapter II Sections III and IV, pages 32-47. Many hydroxyl group containing compounds can be used, including simple aliphatic glycols, aromatic dihydroxy compounds, particularly bisphenols, hydroxyl terminated polyethers, polyesters and polyacetals, among others. Exhaustive lists of suitable polyols are found in the references already mentioned and in many patents, for example in columns 2 and 3 of U.S. Patent No. 3,652,639; columns 2 to 6 in the U.S. Patent. No. 4,421,872 and in columns 4 to 6 of the U.S. Patent. A. No. 4,310,632; These patents are incorporated herein by reference. Preferably, polyester and polyoxyalkylene polyols terminated with hydroxyl are used. The first P1151 / 96MX are generally prepared by well-known methods, for example by the base-catalyzed addition of an alkylene oxide, preferably ethylene oxide (oxirane), propylene oxide (methyloxirane) or butylene oxide (ethyloxy) on an initiator molecule that contains on average two or more active hydrogens. Examples of preferred initiator molecules are dihydric initiators such as ethylene glycol, 1,6-hexanediol, hydroquinone, resorsinol, bisphenols, aniline and other aromatic monoamines, aliphatic monoamines and glycerin monoesters.; trihydric initiators such as glycerin, trimethylolpropane, trimethylolethane, N-alkylphenylenediamines, mono-, di- and trialkanolamines, tetrahydric initiators such as ethylenediamine, propylene diamine 2,4'-, 2,2'-, and 4,4'-methylenedianiline, toluenediamine and pentaerythritol; the pentahydric initiators such as diethylene triamine and -methyl glucoside; and hexahydric and octahydric initiators such as sorbitol and sucrose. The addition of the alkylene oxide to the initiator molecules can be carried out simultaneously or sequentially when more than one alkylene oxide is used, resulting in block, random and block-random polyoxyalkylene polyethers. The number of hydroxyl groups will generally be equal to the number of active hydrogens in the initiator molecule. The processes for preparing these polyethers are described in POLYURETHANE HANDBOOK P1151 / 96MX and POLYURETHANES: CHEMISTRY AND TECHNOLOGY, as well as in many patents, for example U.S. Patents 1,922,451; 2,674,619; 1,922,459; 3,190,927; and 3,346,557. Polyether polyols having exceptionally low levels of unsaturation are preferred, and are prepared using complex dimethalic cyanide catalysts as described below. Polyester polyols also represent preferred polyurethane-forming reagents. These polyethers are well known in the art and are prepared simply by the polymerization of carboxylic acids or their derivatives, for example their acid chlorides or acid anhydrides, with a polyol. polycarboxylic acids different suitable, for example malonic acid, citric acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, cebásico acid, maleic acid, fumaric acid, terephthalic acid and phthalic acid. Suitable polyols, for example the various aliphatic glycols, are trimethylolpropane and trimethylolethane, α-methylglucoside and sorbitol. Also suitable are low molecular weight polyoxyalkylene glycols such as polyoxyethylene glycol, polyoxypropylene glycol and polyoxyethylene polyoxypropylene glycols and heteromeric polyoxyethylene glycols. This list of dicarboxylic acids and polyols is illustrative only and not limiting. An excess of the polyol must be used to P1151 / 96MX ensure hydroxyl termination, although carboxy groups are also reactive with isocyanates. The methods of preparation of these polyester polyols are given in the book POLYURETHANE HANDBOOK, and POLYURETHANES: CHEMISTRY AND TECHNOLOGY. Polyols modified with vinyl polymer are also suitable for polyols. These polymer polyols are well known in the art and are prepared by the in situ polymerization of one or more vinyl monomers, acrylonitrile preference and / or styrene, in the presence of a polyether or polyester polyol, particularly polyols containing a minor amount of natural or induced unsaturation. Methods for preparing these polymer polyols can be found in columns 1 to 5 and in the examples of U.S. Patent No. 3,652,639; in columns 1 to 6 and in the examples of U.S. Patent 3,823,201; particularly in columns 2 to 8 and in the examples of U.S. Patents 4,690,956, and in U.S. Patents 4,524,157; 3,304,273; 3,383,351; 3,523,093; 3,953,393; 3,655,553; and 4,119,586, all of which are incorporated herein by reference. Polyols modified with non-vinyl polymers are also preferred, for example those that are prepared by the reaction of polyisocyanate with an alkanolamine in the presence of a polyol, as shown by the Patent of i'i i c. i /. CMX United States No. 4,293,470; 4,296,213; and 4,374,209; Dispersions of polyisocyanurates containing pendant urea groups as shown in U.S. Patent 4,386,167; and the polyisocyanurate dispersions which also contain biuret linkages as shown in Patent 4,359,541. Other polymer modified polyols can be prepared by reducing the in situ size of the polymers to a particle size of less than 20 μm, preferably less than 10 μm. Many isocyanates are useful in the preparation of urethanes. Examples of these isocyanates can be found in columns 8 and 9 of U.S. Patent 4,690,956, which is incorporated herein by reference and in POLYURETHANE HANDBOOK, Chapter 3, Section 3.2 pages 62-73; and in POLYURETHANES: CHEMISTRY AND TECHNOLOGY, J.H. Chapter II Section II, pages 17-31. Modified isocyanates, such as those containing urethane, biuret, urea, allophanate, uretonimine, carbodiimide or isocyanurate, as bonds, are also useful. Chain extenders may be useful in the preparation of polyurethanes. Chain extenders are generally considered to be very low molecular weight polyfunctional compounds or oligomers reactive with the isocyanate group. The aliphatic glycol chain extenders that are commonly used include ethylene glycol, P1151 / 90MX propylene glycol, 1,4-butanediol and 1,6-hexanediol, and the like. Other additives and auxiliaries are commonly used in polyurethanes. These additives include plasticizers, flow control agents, fillers, antioxidants, flame retardants, pigments, dyes, mold releasing agents and the like. Many of these additives and auxiliary materials are discussed in POLYURETHANE HANDBOOK, Chapter 3, Section 3.4, pages 90-109; and in POLYURETHANES: CHEMISTRY AND TECHNOLOGY, Part II, Technology. The microcellular polyurethane elastomers contain an amount of blowing agent that is inversely proportional to the desired foam density. The blowing agents can be physical (inert) or reactive (chemical) blowing agents. Physical blowing agents are well known to those skilled in the art and include a variety of saturated and unsaturated hydrocarbons having relatively low molecular weights and relatively low boiling points. Examples are butane, isobutane, pentane, isopentane, hexane and heptane. In general, the boiling point is selected so that the heat of the polyurethane-forming reaction promotes volatilization. Until recently, the physical blowing agents that were most commonly used were halocarbons, particularly chlorofluorocarbons. The examples are l'l I M / '> ?, MX methyl chloride, methylene chloride, trichlorofluoromethane, dichlorodifluoromethane, chlorotrifluoromethane, chlorodifluoromethane, chlorinated and fluorinated ethanes, and the like. Brominated hydrocarbons can also be useful. Blowing agents are listed in POLYURETHANE HANDBOOK, page 101. Current research is aimed at reducing or eliminating the use of chlorofluorocarbons, and according to the Montreal Protocol, great efforts have been made to reduce or eliminate the use of agents completely of chlorofluorocarbon (CFC) blowing that exhibit a high potential for ozone depletion (ODP) and a high potential for global warming (GWP). As a result, many new halogenated blowing agents have been commercially offered. A preferred group is, for example, that of alkanes and cycloalkanes with high degree of fluorination (HFCs) and perfluorinated alkanes and cycloalkanes (PFCs). Chemical blowing agents are generally low molecular weight species that react with isocyanates to generate carbon dioxide. Water is the only practical chemical blowing agent that produces carbon dioxide in a proportion of 1 mol to 1 mol, based on the water added to the foam formulation. Unfortunately, water-only blowing systems have not been successful in some applications such as rigid insulation, and therefore it is still common to use TI 1M / 'I MX water together with a blowing agent, for some cases. The high-resilience polyurethane microcellular elastomers are typical blowing foams made purely with water in the blowing step. Blowing agents that are solid or liquid and that decompose to produce gaseous byproducts at elevated temperatures may in theory be useful, but have not been commercially successful. Air, nitrogen, argon and carbon dioxide under pressure can be used in theory, but have not proven to be commercially viable. Research in these areas continues and in particular in view of the tendency to eliminate cluorofluorocarbons. Polyurethane microcellular elastomers generally require a surfactant to promote uniform sizes of the cells and prevent the collapse or crushing of the foam. These surfactants are well known to those skilled in the art and are generally polysiloxane or polyoxyalkylene polysiloxanes. Surfactants are described, for example in OLYURETHANE HANDBOOK, on pages 98 to 101. Commercial surfactants for these purposes are available from a number of sources, for example from Wacker Chemie, Union Carbide Corporation, and Down-Corning Corporation. The processes for the preparation of elastomers P1151 / 96MX polyurethane microcells and the equipment used for this are known to those skilled in the art and are described, for example in POLYURETHANE HANDBOOK, Chapter 4, pages 117-160; and POLYURETHANES: CHEMISTRY AND TECHNOLOGY, Part II, Technology, Chapter VIII, Sections III and IV pages 7-116 and Chapter VIII, Sections III and IV pages 201-238. Having already described the polyurethane starting materials in general form, the polyoxypropylene polyols of the present invention containing internal and random oxyethylene entities have unsaturations less than 0.015 meq / g preferably less than 0.010 meq / g and more preferably 0.001 at 0.007 meq / g. The polyols are preferably prepared using complex dimethalic cyanide catalysts. Traditional basic catalysis using the alkali metal or alkaline earth metal hydroxides or the alkoxides thereof will not produce polyols with these low levels of unsaturation. Suitable catalysts for dimethyl-cyanide cyanide are set forth in U.S. Patent 5,158,922 which is incorporated herein by reference. Preferably, the DMC'TBA catalysts such as those set forth in copending US Patent Application No. 08 / 156,534 are those used. Examples of suitable catalysts are presented below. The use of the preferred catalysts shows P1151 / 96MX a distinctive improvement over DMC'glime catalysts and others. Not only in terms of reduced unsaturation to dramatically decrease the values, but also despite having an unsaturation that can be measured, gel permeation chromatographic analyzes show no detectable low molecular weight components. The ultra low unsaturation polyols are truly monodispersed and are different in class from the DMC'glime catalyzed polyols containing from 5 to 10 molar of the low molecular weight components, presumably the monol. The polymerization is generally carried out from an "initiator" molecule, very often a polyoxypropylene polyol with a relatively low molecular weight, ie 200-700 Da. These initiator polyols can be prepared by the traditional polymerization of propylene oxide with basic catalysis, since at these relatively low molecular weights the unsaturation produced is relatively low and will be diluted as appropriate polymerization. The starting or starting polyols that are in the lower molecular weight range are those that are preferred. After the addition of the dimethalic cyanide catalyst to the starting polyol, the propylene oxide is added at a pressure of about 4 psig (0.27 bar). A rapid drop in pressure indicates that the characteristic P1151 / 96MX called the "induction period" of the dimethalic cyanide catalysts have been terminated and that the additional alkylene oxide can now be added safely at higher pressures, for example about 40 psig (2.72 bar). The added alkylene oxide may initially be propylene oxide in its entirety, or it may be the desired weight ratio of propylene oxide and ethylene oxide. It is important that the ethylene oxide is added together with the propylene oxide since under these conditions the ethylene oxide will be randomly copolymerized to the same degree as with conventional basic catalysis. The resulting polyoxypropylene / polyoxyethylene polyol will have a random distribution of oxyethylene in that part of the polymer formed during the copolymerization. the amount of ethylene oxide that is randomly copolymerized will be between about 1 and 20% by weight based on the weight of the polyol. If the ethylene oxide content is greater than about 20% by weight then the elastomers will exhibit considerable water absorption. Preferably, from 1 to about 15%, more preferably between 5 and about 12% of internal oxyethylene entities are contained in the polyoxypropylene polyols in question. If desired, the polyoxypropylene polyols containing internal oxyethylene random entities of the P1151 / 96MX in question, can be capped with ethylene oxide to provide considerable amounts of the primary hydroxyl groups. When the polyoxypropylene homopolymers prepared using the dimethalic cyanide catalysts are capped with ethylene oxide, the resulting capped polyols rapidly develop a turbidity during storage, for example in a period of 3 to 14 days. It has surprisingly been found that oxyethylene-capped polyoxypropylene copolymers containing internal oxyethylene entities are free of turbidity even after prolonged periods of storage. The amount of the internal oxyethylene content must be an effective amount to produce this characteristic of lack of turbidity. It has been found that this amount depends on the percent by weight of the oxyethylene cap on the finished polyols, with 2.5% by weight of internal oxyethylene entities being sufficient for 14% of oxyethylene-capped polyol, while a larger amount of about 6%. -8% or more, it is required for a polyol with an 18% oxyethylene top. The amount of internal oxyethylene entities that is effective to produce a turbidity-free polyol can be easily determined by preparing a series of internal and random polyoxypropylene / polyoxyethylene copolymers by varying the internal oxyethylene content, and finishing off with the P1151 / 96MX desired amount of ethylene oxide. The product is stored at room temperature for a period of 20 days. The minimum effective amount of the internal oxyethylene entities will be that of the polyol with the lowest content of internal oxyethylene that remains transparent. In preparing the polyurethane elastomers it has been unexpectedly discovered that the use of polyoxypropylene polyols containing about 20% by weight of internal oxyethylene entities improves the green strength, as compared to the polyoxypropylene homopolymers of the same molecular weight. The generation of hardness and resilience in general also increases more rapidly. These effects are surprising since the internal oxyethylene entities do not provide substantially greater amounts of the termination of the primary hydroxyl group than would be expected from the oxyethylene-capped polyols. The latter are expected to react faster. A further improvement in demolding properties and raw strength can be achieved using a multimodal mixture of polyols of different average molecular weights. The polyols are prepared by catalysis of dimethyl cyanide, in particular DMC'TBA, having narrow distributions in molecular weight. The polydispersity of a polymer or polymer mixture can P1151 / 96MX defined by the ratio Mw / Mn where Mw is the weighted molecular weight, Mn is the average numerical molecular weight. The weight-weighted molecular weight is defined as? ICOÍMÍ where M_ is fractional molecular weight i and? Is the weight fraction in the total of the molecular weight component of the fraction i. The average numerical molecular weight is defined as? J.n-¡Mj where, it is defined as above and neither is the numerical fraction of the total molecular weight component of the fraction i. For a theoretically perfect monodisperse polymer where all polymeric species have a single molecular weight, Mw = Mn and the polydispersity Mw / Mn = 1. In practice, true monodispersity is never achieved, and in the application in question, the polymers described as monodisperse have polydispersities of less than 2, and usually of 1.20 or less. The molecular weights reported here are molecular weights of numerical average. The term "multidisperse" as used herein indicates a bis or trimodal distribution, etc., of the molecular weights, each of the individual distributions being essentially monodisperse. These multidisciplinary mixtures are advantageously prepared by mixing two or more essentially monodisperse polyols, or by introducing a second portion of the same initiator molecule or a different starter molecule in the polymerization, in the presence of a suitable catalyst for preparing a polyol.

Pll 51 / .f. X for ultra-low unsaturation, but at a later time. The ultralow unsaturation polyols can be described as truly monodisperse, since they contain a relatively narrow modal molecular weight distribution. Polydispersity, Mw / Mn is usually less than 1.10, for example. By mixing two or more polyoxypropylene polyols of different molecular weights, each contains from 1 to about 20% by weight of internal oxyethylene entities and is essentially monodisperse as characterized by an unsaturation of less than 0.010 meq / g of polyol, or by mixing one of these polyoxypropylene polyols containing 1 to 20% internal oxyethylene entities with a polyoxypropylene homopolymer polyol having an unsaturation of less than 0.010 meq / g, the polyurethane elastomers can be prepared from improved exhibiting mixtures properties of time of demolding and resistance in crude. The polydispersity of the polyol blends is preferably 1.4 or greater. Polydispersities greater than 2.0 are also adequate. The polydispersities of a mixture of two polyols can be calculated using the following equations: Mwmezc? A = MVI1C 1 + Mw2a2, Mnmezc? A = Mn1Mn2 / (Mn1a2 + Mn2ax), PolydispersityMix = Mwmezcla / Mnmezcla P1151 / 96MX wherein Mwx and Mw2 are the weighted molecular weights and Mna and Mn2 are the molecular weights of the numerical average, and a1 and a2 are the weight fractions of the polyols 1 and 2, respectively. The isocyanates useful in the preparation of the elastomers in question can generally be di or organic polyisocyanates, whether aliphatic or aromatic. However, the preferred isocyanates are the commercially available isocyanates of toluene diisocyanate (TDI) and methylene diphenylene diisocyanate (MDI). Toluene diisocyanate is generally used as an 80:20 mixture of 2,4- and 2,6-TDI, although other mixtures are also useful as the commercially available 65:35 mixture as well as the pure isomers. Methylenediphenylene diisocyanate can also be used as a mixture of 2,4'- and 2,2'- and 4,4'-MDI isomers. A wide variety of isomeric mixtures are commercially available. However, 4,4 '-MDI or this isomer which contains only minor amounts of the 2,4'- and 2,2'- isomers is generally preferred, since the latter usually affect the physical properties in a form undesirable for a particular product. Modified isocyanates based on TDI and MDI are also useful, and many are commercially available. To increase the storage stability of the MDI, small amounts, for example, can be reacted in P1151 / 96MX generally less than one mole, of an aliphatic glycol or a polyoxyalkylene glycol of modest molecular weight, or of a triol, with 2 moles of isocyanate to form the urethane-modified isocyanate. Also suitable are the well-known carbodiimide, allophanate, uretonimine, biuret and isocyanates modified with urea based on MDI or TDI. Mixtures of isocyanates and modified diisocyanates can also be used. Also suitable are aliphatic and cycloaliphatic isocyanates such as 1,6-hexanediisocyanate, isophorone diisocyanate, 2,4- and 2,6-methylcyclohexyl diisocyanate and 4,4-dicyclohexylmethane diisocyanate and its isomers, 1,4-bis (2 - (2-isocyanato) propyl) benzene and mixtures of these and other isocyanates. In general, the isocyanate index of the overall formulation is adjusted to be between 70 and 130, preferably between 90 and 110 and more preferably is about 100. Indices between 100 and 105 are particularly suitable. Lower indices will generally result in milder products of lower tensile strength and other physical properties, while higher rates generally result in harder elastomers that require oven curing or curing for extended periods at ambient temperatures for develop their final physical properties. The use of P1151 / 96MX isocyanate rates considerably higher than 130, for example from 200 to 300, generally requires the addition of a trimerization catalyst and results in a less extensible, crosslinked elastomer having considerable polyisocyanurate linkages. The chain extenders for the elastomers of the present invention are preferably aliphatic glycols and polyoxyalkylene glycols with molecular weights of up to about 500 Da, preferably less than 300 Da. Aromatic dihydroxy compounds such as hydroquinone, hydroquinone bis (2-hydroxyethyl) ether (HQEE), bisphenols and 4,4'-dihydroxybiphenyl can also be used. Chain extenders can also be a single chain extender or mixtures. Preference is given to ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, butylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-dihydroxycyclohexane, 1, 4-cyclohexanedimethanol, and the like. Ethylene glycol and, in particular, 1,4-butanediol and 1,6-hexanediol are more preferred. The extendedoiO. Amine chain can also be used but preferably in a very small amount. The resulting elastomers should be characterized as polyurethane elastomers and not as polyurethane / urea elastomers which have acquired a different status in the P1151 / 96MX field of the invention. op ojomplop are ol i 1 pid ami na and t, C > -hexanodiamine, and diethylenetriamine among the aliphatic amine chain extenders. Preferred and preferred aromatic diamine chain extenders are the different isomers of toluenediamine and mixtures thereof, the various methylene diphenyldiamines and mixtures thereof, and preferably the aromatic diamines which react more slowly, such as 4,4'-methylene bis (2). -chloroaniline) (MOCA) and the alkyl substituted and sterically hindered methylenediphenylenediamines and toluenediamines. The polyether polyol component is critical in the elastomers of the present invention. Polyoxyalkylene polyether blends containing polyoxypropylene polyols having from 1 to less than 20% by weight of internal oxyethylene entities exhibiting exceptionally low unsaturation should be used. The measured unsaturation (ASTM test method D-2849-69) is preferably much less than 0.010 meq / g for the polyol mixture. In addition, the individual polyols regardless of the unsaturation of the overall mixture must have individual unsaturations less than 0.015 meq / g. Preferred are polyol mixtures wherein the overall unsaturation is less than 0.007 meq / g and no single polyol has an unsaturation greater than 0.010 meq / g. The use of individual polyols in the mixture is highly preferred, where each polyol has a measured unsaturation Pll 51 / 96MX less than about 0.007 meq / g. In this way, the main portion of the polyol mixture, in order to have an overall setting of less than 0.010 meq / g, must be an essentially monodisperse polyoxypropylene polyol containing from 1 to less than 20% by weight of internal oxyethylene entities which can be prepared by polymerization of a mixture of propylene oxide and ethylene oxide on a starter molecule of suitable functionality, in the presence of a catalyst capable of producing this ultralow level of unsaturation, for example an essentially amorphous cyanide catalyst dimethyl acetate, such as that prepared by the disclosure of the copending United States Patent Application No. 08 / 156,534 which is incorporated herein by reference. An example of the preparation of the catalyst is given in Example 1, and an example of the preparation of the polyol in Example 2. It is noteworthy that the ultralow unsaturation polyols are generally monodisperse, ie there is no detectable low molecular weight component. The polyoxypropylene polyols containing internal oxyethylene entities may also contain other oxyalkylene entities derived from the C3.4 alkylene oxides such as oxetane, 1,2-butylene oxide, and 2,3-butylene oxide, as well as minor amounts of higher alkylene oxides. However, it is preferred that P1151 / 96MX the C3.4 alkylene oxide that predominates is the propylene oxide, and it is still preferred more than the propylene oxide. By the term "polyoxypropylene" as used herein, is meant a polymer whose non-oxyethylene entities are predominantly derived from propylene oxide. The internal oxyethylene random entities are introduced by copolymerization of the ethylene oxide and the propylene oxide (optionally together with any other alkylene oxide) in the presence of a catalyst suitable for the preparation of polyoxyalkylene polyols of ultra-low unsaturation, preferably a dimethalic cyanide, and more preferably and a DMC'TBA catalyst as set forth in copending Patent Application Serial No. 08 / 156,534. The amount of internal oxyethylene entities should be between 1% by weight and less than 20% by weight, preferably between 3% by weight and 15% by weight, and more preferably between 5% and 12% by weight, still with more preferred between 5 and 10% by weight. The use of the catalysts exposed in Aforementioned US Application 08 / 156,534, it is particularly preferred, it is possible to have an extremely low unsaturation in the order of 0.003 to 0.005 meq / g. Furthermore, despite the measurable unsaturation, the gel permeation chromatography of the polyols prepared with these P1151 / 96MX catalysts surprisingly show less detectable molecular weight species, ie the polyols are essentially monodisperse, have a polydispersity of less than 1.20, and typically of about 1.06. Polyoxypropylene polyols topped with polyoxyethylene and free of turbidity contain less than 20% by weight of internal oxyethylene random entities and in general can not be prepared by finishing the addition of propylene oxide and continuing the addition of ethylene oxide, since under these circumstances the polymerization of ethylene oxide, for reasons that are not clearly understood, is not uniform. Polyols resulting from attempts in these polymerizations tend to be mixtures containing essential quantities of unfinished polyoxypropylene polyols containing internal oxyethylene entities and essential quantities of polyols largely oxyethylene-capped. In this way, polyoxyethylene-capped polyols should be prepared by polymerizing the top-off derived from ethylene oxide in the presence of other catalysts, for example traditional alkoxide or alkali metal hydroxide catalysts. For example, between about 0.1 and 2.0% by weight of sodium or potassium methoxide, preferably 0.1 to 0.5% by weight, can be added to the reaction mixture after preparation of the structural polymer. The DMC catalyst does not need Pl 1 'il / .í.MX removed before the addition of the basic catalyst. The mixture is then purified under vacuum to remove the water and / or methanol or other alkanol, after which the ethylene oxide can then be added under conventional conditions. Other methods for the preparation of the polyol are also suitable, providing ultralow unsaturation and obtaining other required properties. The polydispersed polyol blends useful in the invention are advantageously prepared by mixing or more ultra low unsaturation polyols individually, having low polydispersity but different molecular weights, to form a polydispersed polyol blend with a polydispersity greater than 1.4. gel permeation chromatography of these mixtures demonstrates a bi-or trimodal molecular weight distribution, etc., with each of the original polyols representing a relatively narrow peak. Polyol blends may comprise or more polyoxypropylene polyols containing internal oxyethylene entities, an essentially homopolymer polyoxypropylene polyol and one or more polyoxypropylene polyols containing internal oxyethylene entities; an essentially homopolymer polyoxypropylene polyol and one or more polyoxypropylene polyoxypropylene polyols capped with turbidity-free polyoxyethylene containing internal oxyethylene entities; or other l'l 1 M /'If.MX suitable combinations. Preferably, the elastomers are prepared by the prepolymer process, however the one-step process is also useful. In the prepolymer process, the polyoxyalkylene polyol mixture is reacted with an excess of di or polyoxyisocyanate to form a finished isocyanate prepolymer containing between about 1% and 25% of NCO groups, preferably between about 3% and 12% NCO, more preferably about 4 to 10% NCO, and even more preferably about 6% NCO. The preparation of the prepolymer can be catalyzed, preferably by tin catalysts such as dibutyl tin diacetate and dibutyl tin dilaurate, in amounts ranging from about 0.001 to 5% and more preferably from 0.001 to 1%, by weight. The manufacture of the prepolymers is within the skill level of the expert. If desired, the polyol component of the prepolymer can be augmented with functional hydroxyl polyols other than polyoxyalkylene polyols, for example polyester polyols, polycaprolactone polyols, polytetramethylene ether glycols and the like. After the formation of the prepolymer, it is mixed with a proportion of one or more chain extenders so that the isocyanate index is in the range Pl 151/9 M / desired. The prepolymer and the chain extender are mixed vigorously, degassed if necessary and introduced into the appropriate mold. If thermoplastic polyurethanes are desired, the reaction is extruded and granulated or deposited on a traveling band and subsequently granulated. Preferred chain extenders are the aliphatic and cycloaliphatic glycols and the oligomeric polyoxyalkylene diols. Examples of the aliphatic glycol chain extenders are ethylene glycol, diethylene glycol, 1,2- and 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2- and 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydroquinone-bis (2, -hydroxyethyl) ether and polyoxyalkylene diols, such as, for example, polyoxyethylene diols, polyoxypropylene diols, polyoxyethylene / polyoxypropylene, heteric and block diols, polytetramethylene ether glycols, and the like, with molecular weights up to about 300 Da. Ethylene glycol, diethylene glycol, 1-6-hexanediol and 1,4-butanediol are preferred, the latter being particularly preferred. The elastomers in question are quite desirable for microcellular elastomers, for example those suitable for the manufacture of shoe soles. The formulation of these elastomers contains a lower amount of the reactive or volatile blowing agent, P1151 / 96MX proForonain ol first. For example, a high molecular weight can contain between 0.1 and 1.0 percent by weight, preferably between 0.2 and 0.4 percent of water, and have a density of less than 0.8 g / cm 3, preferably between 0.15 and 0.5 g / cm3, and more preferably between 0.2 and 0.4 g / cm, approximately. The isocyanate-terminated prepolymers are generally used in these formulations and have an NCO content higher, in general, than the prepolymers that are used to form non-cellular elastomers. The isocyanate group contents of between 8 and 25 weight percent, more preferably between 10 and 22 weight percent and still more preferably between 13 and 15 weight percent, are suitable. The formulations are generally crosslinked and extended with diol, the crosslinking agent is provided using, in addition to the glycol chain extender, a polyol of low trifunctional unsaturation or higher functionality on the B side, optionally also with a low molecular weight crosslinking agent as diethanolamine (DEOA). Alternatively, the isocyanate terminated prepolymer can be prepared from a polyol of low trifunctional unsaturation or higher functionality, or a mixture of difunctional low unsaturation polyols and higher functionality. The polyols used in considerable amount in the formulation, either incorporated into the prepolymer or on the side Pl 1.1 / 96MX B, must have unsaturations of 0.015 meq / g or less, preferably 0.010 meq / g and the average total unsaturation of all polyol components must also be less than 0.010 meq / g. Having described the invention, this may be understood in greater depth by reference to some specific examples which are given below in order to illustrate the same and which are not intended to be limiting, unless otherwise specified.

Example 1: Preparation of Catalyst Preparation of Zinc Hexacyanocobaltate Catalysts by Homogenization With Terbutyl Alcohol as the Complexing Agent A dimethyl-cyanide catalyst "TBA is prepared by the method set forth in copending application of the United States Serial No. 08 / 156,534. The potassium hexacyanocobaltate (8.0 g) is added to the deionized water (150 mL) in a beaker and the mixture is mixed with a homogenizer until the solids dissolve. In a second beaker, the zinc chloride (20 g) is dissolved in deionized water (30 mL). The aqueous solution of zinc chloride is combined with the cobalt salt solution using a homogenizer to intimately mix the solutions. Immediately after combining the solutions, a mixture of the terbutyl alcohol P1151 / 96MX (100 mL) and deionized water (100 mL) is slowly added to the zinc hexacyanocobaltate suspension, and the mixture is homogenized for 10 minutes. The solids are isolated by centrifugation and then homogenized for 10 minutes with 250 mL of a 70/30 (v: v) mixture of tertiary butyl alcohol and deionized water. The solids are isolated again by centrifugation, and finally they are homogenized for 10 minutes with 250 mL of terbutyl alcohol. The catalyst is isolated by centrifugation and dried in a vacuum oven at 50 ° C and at 30 inches (76.2 cm) of mercury at constant weight.

Example 2: Preparation of Polyoxypropylene Triol with Internal and Random Ethylene Oxide. To a high pressure stainless steel autoclave, 7.6 pounds (3.45 Kg) LHT-240, a polyoxypropyl triol initiated with glycerin of nominal molecular weight of 700 Da and sufficient catalyst prepared according to Example 1 to provide 100 ppm of catalyst in the polyol product. The mixture is stirred and heated at 105 ° C under vacuum to remove traces of water from the triol initiator, and an initial charge of a mixture of propylene oxide and ethylene oxide (990: 10) is added and the reactor pressure It is watched carefully. An accelerated pressure drop indicates that the catalyst has been activated. HE P1151 / 96MX adds more propylene oxide / ethylene oxide within a period of approximately 6.5 hours until a total of approximately 57.5 lbs are added. (26.1 Kg). The reactor is stripped with nitrogen at 117 ° C under vacuum and the product discharged through a cartridge filter to remove the residual catalyst. The resulting polyol is a triol of about 6000 Da containing 10 weight percent of internal oxyethylene entities, and having an unsaturation of about 0.004 meq / g.

Comparative Example 3: Preparation of 6000 Da triol with 1% Polyoxyelie / ene filler. Without Entities Oxyethylene Internals To a stainless steel autoclave of Example 2 are added 7.6 lbs (3.45 Kg) LHT-240 and sufficient sodium catalyst.

Example 1 to provide 100 ppm of catalyst in the polyol product. The reactor was stirred at 105 ° C under vacuum as above, and an initial charge of propylene oxide was added and the pressure recorded. After the catalyst had been activated, a total of 48. 3 lbs. (21.9 Kg) of propylene oxide in a period of . 5 hours. To the polyoxypropylene homopolymer triol obtained in this way was added 332 g of 25 weight percent of sodium methoxide in methanol and 2.8 pounds of hexane. Hexane, methanol and any water present I 11 M / Í.M / removed by depuration at 4 psia (0.27 bar) and 117 ° C for one hour and then for 3 hours more at full vacuum. After debugging, 9.1 lbs (4.1 kg) of ethylene oxide was added at 117 ° C for a period of 1.5 hours. The residual catalysts were then removed by treatment with magnesol and filtration. The resulting product was a polyoxyethylene triol of about 6000 Da having a polyoxyethylene cap of 14 weight percent, without internal oxyethylene entities, and an unsaturation of about 0.006 meq / g. The polyol product developed turbidity after storage at room temperature for a short period.

Example 4: The procedure of Example 3 was followed in the same manner except that the initial oxyalkylation was with 48.3 lbs (21.9 Kg) of a mixture of propylene oxide / ethylene oxide (93: 7) in 6.5 hours at 105 ° C. After the preparation of the polyoxypropylene triol structure containing random ethylene oxide entities, 332 g of 25 weight percent sodium methoxide in methanol was added and the autoclave was cleaned as in Example 3, 9.1 was added. pounds (4.1 Kg) of ethylene oxide at 117 ° C for 1.5 hours. The catalysts were removed using the magnesol treatment and the Pl 1 '.1 /'lí.MX filtration, as in the previous cases. The product was a polyoxypropylene triol containing 5 percent internal and random oxyethylene entities with 14 weight percent polyoxyethylene cap, and an unsaturation of about 0.003 meq / g. The product was free of turbidity even after more than 60 days in storage.

Examples 5 to H: In a manner similar to that presented in Examples 3 and 4, a series of diols and triols topped with polyoxypropylene and polyoxyethylene, and without internal oxyethylene entities, were prepared. The polyols were stored for prolonged periods at room temperature and examined periodically to determine turbidity formation. The results are tabulated in Table 1. Examples 5, 3 and 8 are comparative examples.

I 11 '1 /)? M / TABLE 1 Examples 5.3 and 8 showed turbidity from days 3 to 14 after manufacture. Table 1 shows that an amount as small as 2.5% of internal oxyethylene entities is sufficient to leave polyoxypropylene polyol topped with 14% polyoxyethylene free of turbidity while a similar polyol without internal oxyethylene rapidly showed turbidity. Table 1 also shows that the higher degree of polyoxyethylene topping will require more internal and random oxyethylene entities to make the polyols free of turbidity. Examples 8 with 18% polyoxyethylene capped failed to prevent the generation of turbidity with 5 weight percent of internal oxyethylene entities. In this case, a higher amount of the internal oxyethylene will be required to produce a turbidity-free polyol. ? 11 '.i /' ir M: - Examples 9 to 14 A series of polyoxyethylene diols with 4000 Da molecular weight containing 0, 5, 10, 20, 30 and 40 weight percent of random ethylene oxide entities and internal, was prepared according to Example 2. The diols were reacted with 4,4'-methylenediphenylene diisocyanate to prepare isocyanate-terminated prepolymers containing 6 weight percent NCO, and extended, with 1,4-butanediol for preparing polyurethane elastomers. Dibutyltin dilaurate was used as the polyurethane catalyst, the amount of catalyst was adjusted to give a similar pot life in order that the demoulding times and the green strength could be subjected to a suitable comparison. The mixtures of the polyoxypropylene homopolymer diols with an exceptionally low unsaturation and in which it was found beneficially affected the demolding time and the green strength, as revealed by our co-pending application filed on the same date as the present one, also include for comparison purposes. The results are presented in Table 2. The examples presented in the first column and in the last two columns of Table 2 are comparative examples. il / ') f, MX TABLE 2 Ul As can be seen from the Table, the demolding times, for the polyoxypropylene diols containing 5 weight percent and 10 weight percent of internal and random oxyethylene entities, are similar and in some cases higher than the elastomers prepared from of a monodisperse polyoxypropylene homopolymer diol and multi-dispersed polyoxypropylene homopolymer blends. However, the green strength during the demolding is improved in relation to that of the monodisperse low unsaturation polyoxypropylene homopolymer, and the tensile strengths of the random oxyethylene containing elastomers are considerably higher than for those prepared from the diols of monodisperse or multidispersion polyoxypropylene homopolymer. In addition, the green strength after 60 minutes for the elastomers prepared from polyoxypropylene polyols containing 5 and 10 weight percent internal oxyethylene entities are excellent, while for the elastomers prepared from monodisperse homopolyoxypropylene polyols of 4000 Da be an average. The polyoxypropylene polyols of the present invention, which have up to 20 weight by weight of internal oxyethylene and ultralow unsaturation entities have shown good processing in terms of their time display.

L'U S1 / 96MX demolding and good resistance in crude, commercially useful, as well as have provided elastomers with superior physical properties. However, as already explained above, many elastomers are required to retain their physical properties in humid environments. We have found that polyurethane elastomers prepared from polyoxypropylene polyols with low unsaturation having up to about 20 weight percent of random oxyethylene entities surprisingly show minimal water absorption at room temperature, and elastomers prepared from polyols containing less than 20 weight percent of the random internal oxyethylene content, preferably 5 to 15, exhibit water absorption of less than 10 weight percent, and generally less than 5 weight percent even at 0 ° C , while elastomers prepared with 20 weight percent or more internal oxyethylene entities, as well as polyoxypropylene polyols topped with oxyethylene show absorptions greater than 100 weight percent under these conditions. The absorption of water at 0 ° C, 23 ° C and 50 ° C from elastomers separated from polyols containing various amounts of internal random oxyethylene entities is presented in Figure 1. As can be seen from Figure 1, for elastomers where the problems with respect to the water absorption are expected to be limited to higher temperatures, ie room temperature or higher, up to 20 weight percent of internal oxyethylene entities are suitable for the polyols used to prepare the elastomers. However, when a minimum absorption of water at low temperature is required, for example a low absorption at 0 ° C, the amount of internal oxyethylene entities is preferably less than 15 weight percent, more preferably it is in the range from 5 percent to 10 percent by weight. Under these conditions, at 0 ° C the water absorption is less than 5% by weight, practically the same as that obtained with polyoxypropylene homopolymer polyols and PTMEG polyols but without the problems of processing the first or high costs of the last. The actual water absorption in percent by weight for the elastomers is presented in Table 3 together with a comparative elastomer prepared from a polyoxypropylene diol topped with 20 weight percent ethylene polyoxide and 4000 Da (Example A ), which has an unsaturation of 0.009 meq / g.

Pl 1 '? L / f) i? M / TABLE 3 ABSORPTION OF WATER IN PERCENT IN WEIGHT AS A TEMPERATURE FUNCTION (6% OF PRE-POLYMERS DI / BDO CURED) The development of the * p + 39X resilience hardness generation in relation to time is considerably improved with the polyols in question that contain internal oxyethylene entities compared to the polyoxypropylene homopolymer polyols. Figure 2 shows the resilience generation of the elastomers from a polyoxypropylene homopolymer diol with a molecular weight of 4000 Da (without internal EO) (Graph A), and a monodisperse polyoxypropylene diol of 4000 Da containing 10 percent by weight of oxyethylene random entities (Graph B). To measure the generation of resilience, a series of F'l 1 '? L / 9?, MX identical elastomers prepared from the aforementioned polyols and cured in the oven at 100 ° C. The elastomers were removed at various intervals and the resilience was measured. As can be seen, even though the polyoxypropylene diol containing 10 weight percent internal oxyethylene entities was monodisperse, the resilience generated was considerably higher than that achieved from a polyoxypropylene diol with ultralow unsaturation and monodisperse. In addition, the physical properties of the elastomers prepared from the diol containing internal oxyethylene entities are much greater than those of any of the other two examples. The generation of hardness of the same elastomers is presented in Figure 3. Even though the best way to carry out the invention has been described in detail, those familiar with this technical field to which the invention belongs will recognize that they can be practiced in it. alternative designs and embodiments, as defined in the following claims.

Pl 1 .1 / 9hM

Claims (26)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, what is claimed as property is contained in the following CLAIMS i 1. A polyol topped with polyoxyethylene that has no turbidity and has a lower unsaturation than about 0.015 meq / g of polyol, characterized in that it comprises: a) a polyol with a di-octafunctional polyoxypropylene structure containing from 1 to about 20 weight percent of random and internal oxyethylene entities; b) about 5 to 25 weight percent of polyoxyethylene entities present as a cap on the structural polyol; wherein the structural polyol is prepared by polymerizing a mixture of propylene oxide and ethylene oxide on a di-octafunctional initiator molecule, in the presence of a dimethalic cyanide catalyst; wherein the polyol topped with polyoxyethylene and having no turbidity has an equivalent weight of between about 500 Da and 15,000 Da; where the amount of internal and random oxyethylene entities is such that the formation of

   P1151 / 96MX turbidity in polyols topped with polyoxyethylene for a period of at least 20 days when stored at 23 ° C; and wherein all the percentages by weight are in relation to the weight of the polyols topped with polyoxyethylene and free of turbidity.
2. 2. A polyol topped with polyoxyethylene and having no turbidity according to claim 1, characterized in that the unsaturation is 0.010 meq / g or less.
3. 3. A polyol topped with polyoxyethylene and having no turbidity according to claim 1, characterized in that the unsaturation is 0.007 meq / g or less.
4. 4. A polyol topped with polyoxyethylene and having no turbidity according to claim 1, characterized in that the polyol is a diol or triol.
5. A polyol topped with polyoxyethylene and having no turbidity according to claim 1, characterized in that the polyoxyethylene cap comprises approximately 5 to 15 weight percent of the polyol and the internal and random oxyethylene entities comprise approximately 2 to 10 percent by weight. weight percent of the polyol.
6. 6. A multidisciplinary polyol blend having an average unsaturation of less than about 0.010 meq / g and a polydispersity of greater than 1.4, comprising: two or more individual polyoxypropylene polyols, each of which is essentially a polyol

   P1151 / 96MX monodisperse having an unsaturation less than 0.015 meq / g and an average molecular weight of between about 1000 Da and 20,000 Da, at least one of the two or more individual polyoxypropylene polyols comprises a polyoxypropylene polyol containing approximately 1 and 20 weight percent of internal and random oxyethylene entities.
7. 7. A multidisciplinary polyol blend according to claim 6, characterized in that each of the individual polyoxypropylene polyols has an unsaturation of 0.010 meq / g or less.
8. 8. A multidisciplinary polyol blend according to claim 6, characterized in that each of the individual polyoxypropylene polyols have an unsaturation of 0.007 meq / g or less.
9. 9. A multidisciplinary polyol blend according to claim 7, characterized in that each of the individual polyoxypropylene polyols comprises a polyoxypropylene polyol containing about 1 to 20 weight percent of random and internal oxyethylene entities.
10. 10. A multidisciplinary polyol mixture according to claim 9, characterized in that the individual polyoxypropylene polyols have an unsaturation of less than about 0.007 meq / g and a content of
11. P1151 / 96MX internal random oxyethylene of between about 5 and 15 weight percent 11. A polyurethane elastomer exhibiting less than 10 weight percent water absorption at 23 ° C, the elastomer is the reaction product of: a ) a di- or polyisocyanate at an index of between about 70 to 130; b) a polyoxypropylene polyol component having an average equivalent weight of between about 1000 Da to 8000 Da, an average unsaturation of less than about 0.010 meq / g and comprising at least one polyoxypropylene polyol containing between about 1 to 20 times one hundred oxyethylene internal and random entities and a nominal functionality of two or three, - and c) an oligomeric polyoxyalkylene diol or aliphatic glycol diol chain extender, having a molecular weight of less than about 300 Da. The elastomer according to claim 11, characterized in that the polyoxypropylene polyol component comprises a single polyoxypropylene diol having an unsaturation of less than about 0.007 meq / g and a random and internal oxyethylene content of between about 1 weight percent and about 15 weight percent.
12. P1151 / 96MX
13. 13. The elastomer according to claim 11, characterized in that the polyoxypropylene polyol component comprises a multidisciplinary polyol component having a polydispersity of at least 1.4 and containing at least two individual and essentially monodisperse polyoxypropylene polyols having a lower unsaturation of 0.010 meq / g, at least one of them contains between about 1 and 20 weight percent of random and internal oxyethylene entities.
14. The elastomer according to claim 11, characterized in that the polyoxypropylene polyol comprises a polyoxypropylene diol or triol having an equivalent weight of between about 1000 Da to 8000 Da, an unsaturation of about 0.007 meq / g or less, and a content of internal oxyethylene of about 5 to 12 weight percent based on the weight of the polyoxypropylene diol or triol.
15. 15. A polyurethane elastomer exhibiting less than 10 weight percent water absorption when measured after immersion in water at 0 ° C, the elastomer comprising the reaction product of: a) an isocyanate-terminated prepolymer that contains about 3 to 25 weight percent of NCO and that has been prepared by the reaction of a di- or
16. P1151 / 96MX polyisocyanate containing mostly 4,4'-methylene diphenylene diisocyanate with a polyoxypropylene polyol component comprising: a) i) at least one polyoxypropylene triol A diol having an unsaturation less than about 0.010 meq. / g and an internal and random oxyethylene content of between about 1 and 12 weight percent; a) ii) optionally one or more polyoxypropylene diols or triols having an unsaturation of less than about 0.010 meq / g and an internal and random oxyethylene content of less than 1 weight percent; wherein the average equivalent weight of a) i) and a) ii) together is from about 1000 Da to 8000 Da; with b) an aliphatic diol chain extender selected from the group consisting of ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol at an isocyanate index of between about 70 130.
17. The elastomer according to claim 15, characterized in that the polyol components a) i) and a) ii) together have a polydispersity of 1.4 or greater.
18. The elastomer according to claim 16, characterized in that each of the polyoxypropylene polyols a) i) and a) ii) are essentially
19. P1151 / 96MX monodispersed, with individual polydispersities of less than about 1.
20. 20. The elastomer according to claim 15, characterized in that it comprises the reaction product of water as a reactive blowing agent in an amount between about 0.1 and 1 weight percent based on the total weight of the reactive composition, so that The resulting elastomer is a microcellular elastomer having a density less than 0.8 g / cm. The elastomer according to claim 18, characterized in that the density of the microcellular elastomer is between about 0.2 g / cm 3 and 0.4 g / cm 3. The elastomer according to claim 19, characterized in that the polyurethane polymer comprises the microcellular elastomer and exhibits a water absorption of less than 5 weight percent at 0 ° C.
21. 21. An isocyanate-terminated prepolymer free of precipitates and prepared by reacting an excess of a di- or polyisocyanate component comprising mostly 4,4'-methylene diphenylene diisocyanate, with a polyoxypropylene polyol containing from about 1 to 20 weight percent of internal oxyethylene entities and having a less than about 0.015 meq / g unsaturation.
22. 22. A prepolymer terminated with free isocyanate

    P1151 / 96MX of precipitates and prepared by reacting an excess of a di- or polyisocyanate component, which mostly comprises 4-diisocyanate., 4 '-methylene diphenylene, with the turbidity-free polyoxyethylene capped polyol of claim 1.
23. 23. A turbidity-free isocyanate-terminated prepolymer and prepared by reacting an excess of a di- or polyisocyanate component, which comprises mostly 4,4'-methylene diphenylene diisocyanate, with the turbidity-free polyoxyethylene-capped polyol of claim 2.
24. 24. A turbidity-free isocyanate-terminated prepolymer and prepared by reacting an excess of a di- or polyisocyanate component comprising mostly 4,4'-methylene diphenylene diisocyanate, with the turbidity-free polyoxyethylene capped polyol of claim 6.
25. 25. A polyurethane elastomer exhibiting less than 5 weight percent water absorption at 0 ° C. , which comprises the reaction product of: a) an isocyanate-terminated prepolymer having an NCO content of between about 3 and 25 percent p that and is prepared by reaction of a diisocyanate component comprising 4,4'-methylenediphenylene diisocyanate for the most part, with one or more diols of

    P1151 / 96MX polyoxypropylene having a molecular weight of between about 500 Da at 20,000 Da, an unsaturation of 0.007 meq / g or less and a random internal oxyethylene content of between about 3 and 12 weight percent; with b) 1,4-butanediol at an index of between 70 to 130; in the presence of c) an effective amount of a urethane promoter catalyst.
26. 26. The elastomer according to claim 25, characterized in that the reaction product is furthermore the reaction product of about 0.1 to 1.0 weight percent of water relative to the amounts of a) and b).

    P1151 / 96MX POLYURETHANE ELASTOMERS THAT EXHIBIT IMPROVED PROPERTIES OF DEMOLDE, RESISTANCE IN RAW AND ABSORPTION OF WATER, AND POLYOLS THAT DO NOT PRESENT TURBIDITY

    AND ARE SUITABLE FOR THE PREPARATION OF THESE ELASTOMERS

    SUMMARY OF THE INVENTION Polyurethane elastomers are prepared which exhibit improved green strength while maintaining short demold times; the preparation is made from ultra low unsaturation polyoxypropylene polyols containing up to 20 weight percent of internal and random oxyethylene entities. The elastomers absorb less than 10 weight percent water at 0 ° C. The polyoxyethylene polyols containing the internal polyoxyethylene entity can be used to prepare polyols of ultra low unsaturation polyoxyethylene which are free of turbidity and which can be used to prepare turbidity-free 4,4 '-MDI prepolymers. The multi-dispersed mixtures of polyoxypropylene polyols, which contain monodisperse oxyethylene internal entities of ultra-low unsaturation, provide still further improvements in the processing of the elastomer.

    P1151 / 96MX