HK1056568A - Polyurethane elastomers having improved physical properties and a process for the production thereof - Google Patents
Polyurethane elastomers having improved physical properties and a process for the production thereof Download PDFInfo
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Description
Technical Field
The present invention relates to a polyurethane elastomer and a production method thereof. More particularly, the present invention relates to polyurethane elastomers having improved physical properties, polyol components and isocyanate-terminated prepolymers or quasi-prepolymers useful in the preparation of such elastomers, and to a one-shot process for preparing polyurethane elastomers from these materials. Preferably, such elastomers are obtained by chain extending an isocyanate-terminated prepolymer or quasi-prepolymer prepared with a polyol component having a number average molecular weight of from about 1000 to about 3000 daltons. The polyol component includes a low molecular weight, high polydispersity index polyol and a low monol (low monol) polypropylene glycol.
Background
Polyurethane elastomers are widely used in different applications such as gaskets and sealing materials, medical devices, ski boots, shock absorbers and conveyor rollers, to name a few. Elastomers prepared based on isocyanate-terminated prepolymers or quasi-prepolymers in combination with polytetramethylene ether glycol (PTMEG), polycaprolactone, and polyester polyols have the strength, hardness, and other properties that are essential for demanding applications.
However, PTMEG, polycaprolactone, and polyester polyols are expensive starting materials. Therefore, these polyol components also produce product polyurethane elastomers at a higher price.
It has been proposed to use polyoxypropylene glycols as a possible alternative to PTMEG in the formulation of elastomeric prepolymers, however the properties of the elastomers so obtained are comparable to those obtained using PTMEG.
The patent literature teaches the benefits of using polyoxypropylene diols of low unsaturation, but at the same time recognizes that elastomeric products prepared from such polyols produce products that exhibit low modulus values, low hardness values, low compression set and abrasion resistance, and present processing problems.
Methods have been undertaken to improve these physical properties using polyol mixtures and to reduce or eliminate the process problems encountered with the use of these low unsaturation polyols. For example, U.S. patent 5,648,447 discloses polyurethane elastomers obtained by chain extending a prepolymer with an aliphatic diol or aromatic amine with a polyol component comprising PTMEG and a low monol polyoxypropylene polyol having an equivalent percent of 5 to 35. However, the patent also teaches that if more than 35 equivalent percent of a low monol polyoxypropylene diol is used, the tensile strength of the elastomer decreases rapidly and the elongation value is inferior to that of an elastomer prepared with only the low monol polyoxypropylene diol. Since the equivalent percentage of such diols is required to be less than 35 to maintain the tensile strength and elongation values, the use of polyoxypropylene glycols having low monol content is not sufficiently economical.
As disclosed in U.S.5,648,447, it has been found that it is necessary to have more than about 20% isocyanate (specifically, MDI) in the system to achieve hardness levels achievable using similar PTMEG systems. In addition, the conditions for obtaining optimum mechanical properties are such that only sufficient chain extension of the prepolymer is catalyzed, so that the pot life of the system is about 2 minutes or less. Thus, elastomers with processing times exceeding 2 minutes cannot be produced with this system if one does not want to lose the mechanical properties of the elastomeric product.
Among the known processes for preparing polyurethane elastomers, the one-shot process is considered particularly advantageous. For example, U.S. patents 5,668,239 and 5,739,253 both disclose a one-shot process for preparing polyurethane/urea elastomers from isocyanate-terminated prepolymers, polyether polyols, and chain extenders.
It would therefore be of interest to develop an elastomer-forming composition in which the majority of the polyol component used is a low monol polyoxypropylene diol, which produces an elastomer having hardness, modulus, compression set, abrasion resistance and processability comparable to elastomers currently produced only with conventional high performance polyols.
Disclosure of Invention
It is an object of the present invention to provide a polyol component for producing a polyurethane elastomer having good processing characteristics and physical properties even if the processing time is longer than 2 minutes, which contains a large amount of a low-cost, low monool content polyoxypropylene polyol.
It is another object of the present invention to provide an NCO-terminated prepolymer or quasi-prepolymer with which polyurethane elastomers can be prepared having properties comparable to elastomers prepared with high performance polyols alone, such as PTMEG, polycaprolactone and polyester.
It is a further object of the present invention to provide polyurethane elastomers characterized by good hardness, modulus, elongation, abrasion resistance and compression properties.
It is a further object of the present invention to provide an economical process for preparing polyurethane elastomers having good mechanical properties, which does not require unacceptably short reaction times during processing of the elastomer-forming material.
These and other objects which will be apparent to those skilled in the art are achieved by the use of a polyol component which is a mixture or blend having a number average molecular weight of from about 1000 to 3000 daltons. Such polyol components must contain: (1) a major amount (i.e., greater than 60 weight percent of the total weight of the polyol component) of a low monol content polyoxypropylene polyol having a number average molecular weight of about 2000 to 12,000 daltons, an unsaturation of less than or equal to 0.02meq/g and (2) a minor amount (i.e., less than 40 weight percent of the total weight of the polyol component) of a low molecular weight polyol having a high polydispersity index (i.e., a polydispersity index greater than 1.1). This polyol component is reacted with an isocyanate, an isocyanate-terminated prepolymer or an isocyanate-terminated quasi-prepolymer. The elastomers prepared according to the present invention are most preferably synthesized by chain extension of an isocyanate-terminated prepolymer or quasi-prepolymer prepared by reacting a chemical excess of one or more di-or polyisocyanates with at least one polyol of a polyol component or a polyol component to give a prepolymer or quasi-prepolymer.
Description of the preferred embodiments
The polyurethane elastomers prepared according to the present invention are preferably prepared by chain extension of isocyanate-terminated prepolymers or quasi-prepolymers using one or more conventional chain extenders. The isocyanate-terminated prepolymer may be prepared by reacting one or more di-or polyisocyanates with a polyol component having a number average molecular weight of from about 1000 to 3000 daltons. This polyol component contains: (1) a low monol polyoxypropylene polyol, and (2) a low molecular weight polyol having a polydispersity index greater than 1.1. According to the present invention, the isocyanate is first reacted with a small amount (e.g., 10 equivalent percent) of the total polyol component to produce a quasi-prepolymer, which is then reacted with the resin portion (part B) of the elastomer formulation, which contains the remaining polyol component and a chain extender, to produce the elastomer. The elastomers of the present invention may be prepared by any method known to those skilled in the art, including a one-shot process.
The isocyanates of the present invention include any of the known aromatic, aliphatic and cycloaliphatic di-or polyisocyanates which are themselves useful in the production of elastomers and which prepare isocyanate-terminated prepolymers or quasi-prepolymers for use in the production of elastomers. Examples of suitable isocyanates include: 2, 4-and 2, 6-tolylene diisocyanate and isomer mixtures thereof, in particular 80: 20 mixtures of the 2, 4-and 2, 6-isomers; 2, 2 ', 2, 4 ' -and especially 4, 4 ' -methylenediphenylene diisocyanate and isomer mixtures thereof; polyphenylene polymethylene polyisocyanate (poly-MDI, PMDI); homologs of saturated cycloaliphatic PMDI such as 2, 4-and 2, 6-methylcyclohexane diisocyanate and 2, 2 ', 2, 4 ' -and 4, 4 ' -methylenedicyclohexylene diisocyanate and other isomers thereof; isophorone diisocyanate; 1, 4-butane diisocyanate; 1, 5-pentane diisocyanate; 1, 6-hexane diisocyanate; 1, 4-cyclohexane diisocyanate, and the like.
Modified diisocyanates and polyisocyanates may also be used in the present invention. Suitable modified isocyanates include: urea-modified isocyanates; a biuret modified isocyanate; a urethane-modified isocyanate; isocyanurate-modified isocyanates; allophanate-modified isocyanates; carbodiimide-modified isocyanate; uretdione modified isocyanates; ureidoimine modified isocyanates, and the like. These modified isocyanates are commercially available and can be prepared by reacting the isocyanates with less than a stoichiometric amount of isocyanate-reactive compounds or with themselves. For example, urea-modified isocyanates and urethane-modified isocyanates can be prepared by reacting di-or polyisocyanates with small amounts of water or diamines, respectively, or with ethylene glycol. Carbodiimide, uretonimine and isocyanurate modified isocyanates are prepared by the interaction of an isocyanate with itself in the presence of a suitable catalyst.
Of the isocyanates listed above, Toluene Diisocyanate (TDI), methylene diphenylene diisocyanate (preferably 4, 4' -MDI), carbodiimide-modified MDI and aliphatic and cycloaliphatic isocyanates (particularly 1, 6-hexane diisocyanate and isophorone diisocyanate) are particularly preferred; various methylcyclohexylene diisocyanates; and various methylenedicyclohexylene diisocyanates. Mixtures of isocyanates are also suitable, in particular mixtures of TDI with MDI and mixtures of MDI with carbodiimide-modified MDI.
The low molecular weight polyols useful in the present invention have a polydispersity index greater than 1.1 and include any known polyol that meets the following criteria: (1) a number average molecular weight of about 400 to 1000 daltons; and (2) the ratio of weight average molecular weight to number average molecular weight (polydispersity index) is greater than 1.1, preferably greater than 1.2, most preferably greater than 1.3. Suitable polyols include polyether polyols and polyester polyols meeting the above criteria. These low molecular weight, high dispersion polyols are typically difunctional. Lesser amounts of higher functionality polyols (e.g., less than about 20% by weight, preferably less than about 10% by weight, most preferably less than about 5% by weight, relative to the total polydispersity index of greater than 1.1) and meeting the above criteria are also included.
Polyols having a polydispersity index greater than 1.1 have a number average molecular weight of from about 400 to 1000 daltons, preferably from about 500 to 1000 daltons, and most preferably from about 600 to 1000 daltons. Unless otherwise stated, the molecular weights and equivalent weights in daltons stated herein are the index average molecular weight and the number average equivalent weight.
The high polydispersity index low molecular weight polyols of the present invention are generally present in the polyol component in an amount of from 5 to 40 weight percent, preferably from 10 to 30 weight percent, and most preferably from 15 to 25 weight percent.
Specific examples of low molecular weight, high polydispersity index polyols suitable for use in the present invention include polytetramethylene ether glycol and polyester polyols meeting the above criteria. Preferred are polytetramethylene ether glycols having a molecular weight of from about 400 to 1000 daltons and a polydispersity index of at least 1.3.
Polytetramethylene ether glycol (PTMEG) meeting the above criteria is commercially available. PTMEG is typically prepared by ring opening polymerization of tetrahydrofuran, typically in the presence of a Lewis acid as a catalyst. PTMEG polyols have a relatively high ratio of methylene groups to oxygen and provide low water absorption and good hydrolytic stability. Particularly useful PTMEG has a molecular weight of about 400 to 1000 daltons, preferably about 500 to 1000 daltons, and a polydispersity index equal to or greater than 1.3.
Polyester polyols are also commercially available. These polyester polyols can be broadly classified as homo-, co-and ter-polymers, although some of these terms are used interchangeably. Homopolyesters are prepared by polymerizing monomers containing both hydroxyl and carboxylic acid functional groups or their chemical equivalents. The most common homopolyester is polycaprolactone, which is prepared by the ring-opening polymerization of epsilon-caprolactone by interesterification. The polycaprolactone polyester has a uniform head/tail structure, which can improve crystallinity. Other lactones and molecules containing both hydroxyl and carboxylic acid functionality are also suitable for preparing polycaprolactone polyols. The addition of other di-or higher functionality molecules with hydroxyl functionality or carboxylic acid functionality can adjust the functionality or structure of the polycaprolactone polyol.
Co-and ter-copolyester polyols are also commercially available as the reaction product of a chemical excess of a diol and a dicarboxylic acid or esterifiable derivative thereof. When a single diol and a single dicarboxylic acid are reacted, the resulting product is a binary copolyester, commonly referred to simply as a "polyester". Examples of such copolyesters are: polyethylene adipate of 1, 2-ethylene glycol and adipic acid; polybutylene adipate of 1, 4-butanediol and adipic acid; 1, 2-ethylene glycol and terephthalic acid or their derivatives which can undergo esterification or transesterification, such as polyethylene terephthalate formed from dimethyl terephthalate, and the like. When two or more diols and/or two or more dicarboxylic acids are used in the polyester reaction, the product is a terpolymer. An example of such a terpolymer is poly (ethylene butylene adipate) prepared from a mixture of 1, 2-ethylene glycol, 1, 4-butanediol, and adipic acid. It is also possible to add generally minor amounts of tri-or higher functionality polyols and tri-or higher functionality carboxylic acids to prepare polyester polyols having an average functionality of greater than 2.
Both homopolyester polyols, such as polycaprolactone, and copolyester polyols formed from only one diol and one dicarboxylic acid are suitable for use in the present invention.
The polyol component composition of the present invention is primarily characterized by the use of a low monol polyoxypropylene polyol in combination with a low molecular weight polyol having a polydispersity index greater than 1.1. Polyoxypropylene polyols have traditionally been prepared by base-catalyzed oxypropylation of a suitable hydroxyl-containing oxyalkylatable initiator molecule in the presence of a base oxypropylation catalyst such as sodium or potassium hydroxide or the corresponding alkoxide. Under basic alkoxylation conditions, certain propylene oxides rearrange to form an unsaturated monohydroxy functional compound, allyl alcohol, which then itself serves as another oxyalkylatable initiator molecule. Rearrangement continues during alkoxylation, while changes in the functionality and molecular weight distribution of the product are measured.
Continued incorporation of monofunctional species reduces the overall functionality so that 2000 daltons equivalents, the diol initiated polyol may contain 40 to 50 mole% or more monofunctional species. As a result, the "nominal" or "theoretical" functionality 2 of the diol initiator is reduced from about 1.6 to 1.7 or less. The relative amount of monol present is generally determined by determining the unsaturation of the polyol, expressed as milliequivalents of unsaturation per gram of polyol (meq), hereinafter "meq/g". The degree of unsaturation was determined according to ASTM D-2849-69, "Testing Urethane foam polyol Raw Materials". Typically, the base-catalyzed equivalent range of polyoxypropylene diol is within 2000 daltons and the measured unsaturation is in the range of 0.07 to 0.12 meq/g. Conventional base-catalyzed processes limit the practical equivalent weight of polyoxypropylene glycols to about 2000 daltons due to the high degree of unsaturation and the high content of monofunctional species reflecting unsaturation.
Several methods have been proposed to reduce the degree of unsaturation and the content of monofunctional species. Cesium hydroxide and rubidium hydroxide are used to replace the less expensive sodium and potassium hydroxides to reduce the degree of unsaturation. (see, e.g., U.S. patent 3,393,243.) barium hydroxide and strontium hydroxide are also used. (see, e.g., U.S. Pat. Nos. 5,010,187 and 5,114,619.) U.S. Pat. No. 4,282,387 discloses the use of metal carboxylate catalysts, such as calcium naphthenate, with or without tertiary amines as co-catalysts. The patent states that this catalyst reduces the degree of unsaturation of the polyol to the range of 0.04 meq/g. However, the limited improvement in the price and degree of unsaturation after use of such catalysts has made their commercial use unattractive.
Double metal cyanide complex catalysts as disclosed in U.S. Pat. No. 5,158,922 make it possible to produce polyether polyols having unsaturation in the range of 0.015 to 0.018 meq/g. Such double metal cyanide complex catalysts have been improved to the extent that particularly low unsaturation polyols, such as 0.002 to 0.007meq/g of polyol, can be prepared (see U.S. Pat. Nos. 5,470,813 and 5,482,908). Although measurable unsaturation suggests at least some monol content, the low molecular weight species that it is desired to produce are difficult to detect by gel permeation chromatography. Moreover, the polydispersity of the product is so low that the polyol can be considered to be practically monodisperse.
The polyoxypropylene polyol used in the present invention is limited to a low monol content. In particular, the monol content, which is related to the degree of unsaturation of the polyol, must be less than about 0.02meq/g, preferably less than 0.010meq/g, and most preferably about 0.007meq/g or less. The polyoxyalkylene polyol is preferably difunctional, and small amounts of higher functionality polyols may also be used. The term "polyoxypropylene polyol" as used herein includes polyoxypropylene diols containing up to about 20% by weight of tri-or higher functionality polyoxypropylene-based compounds. The polyoxypropylene diol is preferably a homopolypropylene glycol. However, it is also possible to use random, block or block/random copolyols which contain up to 30% by weight of ethylene oxide moieties, preferably not more than 20% by weight of ethylene oxide moieties. Polyoxypropylene polyols contain relatively small amounts of higher alkylene oxide derived moieties, and in particular may contain small amounts (i.e., less than 10% by weight) of 1, 2-and 2, 3-butylene oxide derived moieties. The term "polyoxypropylene polyol" also includes these primary propylene oxide-derived polyoxyalkylene copolymers. Preferably, the polyoxypropylene polyol is substantially all propylene oxide derived, most preferably substantially difunctional. The low monol polyoxypropylene polyol may have a molecular weight of from about 2000 daltons to 12,000 daltons, preferably from about 3000 daltons to 8000 daltons, and most preferably from about 3000 daltons to 4500 daltons.
The polyol component used in the present invention has an average molecular weight of from about 1000 to 3000 daltons, preferably from 1000 to 2500 daltons, and most preferably from about 1000 to 2000 daltons. The average unsaturation of the polyol component is generally less than 0.02meq/g, preferably less than 0.01meq/g, most preferably less than 0.007 meq/g. The amount of low molecular weight polyol having a polydispersity index of greater than 1.1 and low monol content polyoxypropylene polyol and all other isocyanate-reactive materials in the polyol component is such that the average molecular weight and average unsaturation of the total polyol component are within these specified ranges. Furthermore, the low monol polyoxypropylene polyol must comprise at least 60 weight percent, preferably at least 70 weight percent, and most preferably at least 75 weight percent of the total polyol component.
The isocyanate-terminated prepolymers or quasi-prepolymers of the present invention typically contain isocyanate groups in an amount expressed as a weight percent (% NCO) of from 3 to 20% NCO, preferably from 4 to 14% NCO, and most preferably from 4 to 10% NCO. The prepolymer may be prepared by conventional techniques. For example, one suitable isocyanate-terminated prepolymer may be prepared by reacting a mixture of a low molecular weight polyol having a polydispersity index greater than 1.1 and a low monol content polyoxypropylene polyol with an isocyanate in sufficient chemical excess to provide the desired content of isocyanate groups. Mixtures of prepolymers can also be used, for example, by reacting the isocyanate only with a chemical excess of a low molecular weight polyol having a polydispersity index greater than 1.1 to form a first prepolymer, reacting the excess isocyanate with a low monol polyoxypropylene polyol to form a second prepolymer, and then mixing the two prepolymers. The prepolymer reaction components are preferably reacted under nitrogen without impurities at temperatures ranging from room temperature to about 100 c, preferably from 40 c to 80 c. Urethane group promoting catalysts such as tin catalysts may be added if desired, but are generally not required. Methods for the preparation of prepolymers are well known, for example as editable in G.OertelPolyurethane HandbookHanser Publication, Munich, 1985 or a paper in j.h. saunders and k.c. frischPolyurethanes：Chemistry and TechnologyThis was found in Interscience Publishers, New York, 1963.
The chain extender used in the preparation of the elastomer of the present invention includes conventional glycol chain extenders such as 1, 2-ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1, 4-butanediol, 1, 6-hexanediol, neopentyl glycol, O' -bis (2-hydroxyethyl) -hydroquinone, 1, 4-cyclohexanedimethanol, 1, 4-dihydroxycyclohexane, and the like. 1, 2-ethylene glycol, propylene glycol, 1, 4-butanediol, 1, 6-hexanediol are preferred, and 1, 4-butanediol is particularly preferred.
Small amounts of crosslinking agents such as glycerol, trimethylolpropane, diethanolamine and triethanolamine can be used in combination with the glycol chain extender, but are not preferred.
Aromatic amine chain extenders are also suitable for use in the present invention. Preferred amine chain extenders are aromatic amines such as the various toluenediamines and methylenedianiline, especially substituted aromatic amines, which slow down the reaction due to their electronic and steric effects, examples of which are MOCA (4, 4 '-methylene-bis-O-chloroaniline), M-CDEA (4, 4' -methylenebis (3-chloro-2, 6-diethylaniline), and various aralkylated toluenediamines and methylenedianiline.
The isocyanate-terminated prepolymer is reacted with a chain extender and optionally a cross-linker, and has an isocyanate index of from 70 to 130, preferably from 90 to 110, most preferably from 95 to 105. The reaction forms elastomers having a hardness preferably in the range of shore a 50 to shore D60, preferably shore a 60 to shore a 95. Harder and softer elastomers may also be prepared. Such prepolymers can be cured by heating with the aid of catalysts, such as dibutyltin diacetate, stannous octoate or dibutyltin dilaurate, amine catalysts or mixtures thereof. If microcellular elastomers are desired, small amounts of physical or chemical blowing agents, in particular water, may be added; or by reaction with air, nitrogen or CO2Thoroughly mixing to foam the cured elastomer; or mixing liquid CO2Is mixed into the curable elastomer reaction mixture. Water is the preferred blowing agent, preferably used in an amount to provide a microcellular elastomer having a density in the range of from 0.15 to 0.8g/cm3Preferably 0.2 to 0.5g/cm3。
The reaction mixture of isocyanate-terminated prepolymer, chain extender, optional blowing agent, pigment, thermal and UV stabilizer, filler, reinforcing agent, cross-linking agent, and other additives and adjuvants may be thoroughly mixed and then injected into a suitable die for extrusion or deposition on a moving conveyor. If all of the reaction components are substantially difunctional, the extruded or deposited elastomer can continue to be pelletized and remelted (i.e., the elastomer is a Thermoplastic Polyurethane (TPU)). The TPU may be fed into an extruder or other equipment, remelted, then injection molded, blow molded, etc., to form a number of different products.
In the quasi-prepolymer technique, quasi-prepolymers are prepared by preparing an excess of isocyanate and only a small part of the polyol component or a small part of at least one polyol in the polyol component in the same manner as the isocyanate-terminated prepolymers described above. However, due to the smaller amount of polyol component reacted with the isocyanate, the% NCO content of the quasi-prepolymer is higher than the% NCO content of the prepolymer. Such quasi-prepolymers typically have an isocyanate group content of 14 to 20% NCO. When a quasi-prepolymer is used, the remaining polyol component is mixed with the glycol chain extender or separately dosed into the previous mixture.
One particularly useful quasi-prepolymer technique is to use all or substantially all of the low monol polyoxyalkylene glycol in the preparation of the quasi-prepolymer, without or substantially without the use of low molecular weight polyols having a polydispersity index greater than 1.1. The quasi-prepolymer thus prepared is then chain extended with two components, a low molecular weight polyol having a polydispersity index of greater than 1.1 in part B of the formulation and a chain extender. The relative amounts of low molecular weight polyol having a polydispersity index of greater than 1.1 and low monol content polyoxyalkylene glycol are adjusted between the quasi-prepolymer and part B such that the elastomeric product contains relatively 60 to 95 weight percent low monol content polyoxyalkylene polyol and about 5 to 40 weight percent low molecular weight polyol having a polydispersity index of greater than 1.1.
The present invention may also use a one-step technique. In the one-step technique, the isocyanate component is not pre-reacted with any substantial portion of the polyol component, and all or substantially all of the polyol component and chain extender are separated from the isocyanate component in one or more streams for mixing. Using a one-shot process, if prolonged demolding and curing is not permitted, it is desirable that a portion of the polyol component be a low monol content polyoxyethylene capped polyoxypropylene diol, or a minor proportion of a conventional poly-primary hydroxyl polyoxypropylene diol in the formulation.
Having generally described the invention, a more complete understanding can be obtained by reference to the specific examples provided herein, which are intended to be illustrative only and are not intended to be limiting unless otherwise specified.
Examples
The materials used in the examples are as follows:
polyol A Polytetramethylene ether glycol having a number average molecular weight of 2,000
Polyol B having a number average molecular weight of 4,000 and a ring unsaturation of 0.005meq/g
Oxopropane type diols
Polyol C number average molecular weight 4,000, 15% internal ethylene oxide, not
Propylene oxide type diol having a degree of saturation of 0.005meq/g
Polyol D has a number average molecular weight of 4,000, contains 30% internal ethylene oxide, and does not
Propylene oxide type diol having a degree of saturation of 0.005meq/g
Polyol E number average molecular weight 4,000, 40% internal ethylene oxide, none
Propylene oxide type diol having a degree of saturation of 0.005meq/g
Polyol F contained 10% random internal ethylene oxide, had a number average molecular weight of 3,000,
propylene oxide type diol having unsaturation degree of 0.005meq/g
Polyol G Poly (ester) having number average molecular weight of 8,000 and unsaturation degree of 0.005meq/G
Propylene oxide type diol
Polyethylene glycol with polyol H number average molecular weight of 600 and polydispersity index of 1.01
Polytetramethylene having a polyol I number average molecular weight of 650 and a polydispersity index of 1.6
Ether glycols
Polypropylene glycol having polyol J number average molecular weight of 650 and polydispersity index of 1.1,
by mixing 21.6 wt.% of a polypropylene glycol having a molecular weight of 425 and
74.8 wt.% polypropylene glycol with molecular weight 760 obtained
Polypropylene glycol having a polyol K number average molecular weight of 650 and a polydispersity index of 1.65,
prepared by mixing 5 wt.% of low unsaturation having a molecular weight of 4000
And polypropylene glycol (commercially available from Bayer Corporation under the name
Designated Acclaim 4200), 15 wt.% molecular weight 2000
Low unsaturated polypropylene glycol (available from Bayer Corporation)
Commercially available, designation Acclaim 2200), 30 wt.% of molecules
An amount of 1000 of a low unsaturated polypropylene glycol (available from Bayer)
Available from Corporation under the name PPG-1000), 25wt. -%)
Low unsaturated polypropylene glycol of molecular weight 760 (available from Bayer)
Available from Corporation under the name PPG-725), 17wt. -%
Low unsaturated polypropylene glycol of molecular weight 425 (available from Bayer)
Available from Corporation under the name PPG-425), and 8wt. -%
Tripropylene glycol.
Polytetramethylene having a polyol L number average molecular weight of 250 and a polydispersity index of 1.1
Ether glycols
Polyol M contains 20% random internal ethylene oxide, has an average molecular weight of 4000,
propylene oxide type diol having unsaturation degree of 0.005meq/g
BDO 1, 4-butanediol
Isocyanate 4, 4' -diphenylmethane diisocyanate
(ISO)
Examples 1 to 5 and comparative examples C1 to C7
The polyurethane elastomer was prepared by chain extending an NCO terminated prepolymer having an NCO content of 6% with 1, 4-butanediol and having an isocyanate index of 105. The isocyanate index remains the same to ease the comparison between different formulations. Each prepolymer tested was prepared by reacting a stoichiometric excess of 4, 4' -MDI with one or more polyether diols to give an average equivalent weight of the polyol component of 1000 daltons. In a comparative example, the prepolymer was prepared by reacting 4, 4' -MDI with only polyoxypropylene diol (i.e., no PTMEG). Specific polyol components used to prepare the prepolymer and the elastomer are given in table 1A. The reaction mixture was then poured into a mold where the mixture was cured at 105 ℃ for 16 hours. The elastomer was then demolded and left for 4 weeks. The physical properties of the polyurethane elastomer prepared were then measured. The results are reported in table 1B.
TABLE 1A
| Examples | C-1 | C-2 | C-3 | 1 | 2 | 3 | C-4 | 4 | 5 | C-5 | C-6 | C-7 |
| Polyol A, pbw | 100 | --- | 40 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Polyol B, pbw | --- | 100 | 60 | 80.6 | --- | --- | --- | --- | --- | 93.3 | 82.4 | 80.6 |
| Polyol C, pbw | --- | --- | --- | --- | 80.6 | --- | --- | --- | --- | --- | --- | --- |
| Polyol D, pbw | --- | --- | --- | --- | --- | 80.6 | --- | --- | --- | --- | --- | --- |
| Polyol E, pbw | --- | --- | --- | --- | --- | --- | 80.6 | --- | --- | --- | --- | --- |
| Polyol F, pbw | --- | --- | --- | --- | --- | --- | --- | 86.2 | 39.7 | --- | --- | --- |
| Polyol G, pbw | --- | --- | --- | --- | --- | --- | --- | --- | 39.7 | --- | --- | --- |
| Polyol H, pbw | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | 17.6 | --- |
| Polyol I, pbw | --- | --- | --- | 19.4 | 19.4 | 19.4 | 19.4 | 13.8 | 20.7 | --- | --- | --- |
| Polyol J, pbw | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | 19.4 |
| Polyol K, pbw | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Polyol L, pbw | --- | --- | --- | --- | --- | --- | --- | --- | --- | 6.7 | --- | --- |
| M of low molecular weight polyolsw/Mn | --- | --- | --- | 1.6 | 1.6 | 1.6 | 1.6 | 1.6 | 1.6 | 1.1 | 1.01 | 1.1 |
| BDO pbw | 8.4 | 7.9 | 8.1 | 8.4 | 8.4 | 8.4 | 8.4 | 8.4 | 8.4 | 8.4 | 8.4 | 8.4 |
| ISO pbw | 37.0 | 29.3 | 32.4 | 37.0 | 37.0 | 37.0 | 37.0 | 37.0 | 37.0 | 37.0 | 37.0 | 37.0 |
| NCO/OH | 2.96 | 4.70 | 3.70 | 2.96 | 2.96 | 2.96 | 2.96 | 2.96 | 2.96 | 2.96 | 2.96 | 2.96 |
| Average molecular weight of the mixture | 2000 | 4000 | 2000 | 2000 | 2000 | 2000 | 2000 | 2000 | 2000 | 2000 | 2000 | 2000 |
TABLE 1B
1Hardness, Shore A hardness (ASTM D2240)2Pendulum bob rebound,% (ASTM D1054)3Tensile Strength, pounds per square inch (ASTM D412)4Elongation at break,% (ASTM D412)5100% modulus, pounds per square inch (ASTM D412)6200% modulus, pounds per square inch (ASTM D412)7300% modulus, pounds per square inch (ASTM D412)8400% modulus, pounds per square inch (ASTM D412)9Type C tear, pounds per inch (ASTM D624)10Compression set,% (ASTM D395, method B)11Tay abrasion, mg loss/1000 revolutions12Compression deformation: stress @ 5% compression, pounds per square inch (ASTM D575, method A)13Compression deformation: stress @ 10% compression, pounds per square inch (ASTM D575, method A)14Compression deformation: stress @ 15% compression, pounds per square inch (ASTM D575, method A)15Compression deformation: stress @ 25% compression, pounds per square inch (ASTM D575, method A)
| examples/Properties | C-1 | C-2 | C-3 | 1 | 2 | 3 | C-4 | 4 | 5 | C-5 | C-6 | C-7 |
| Hard.，Shore A1 | 84 | 75 | 80 | 79 | 80 | 80 | 76 | 76 | 79 | 83 | 77 | 80 |
| ％Rebound2 | 71 | 69 | 72 | 64 | 63 | 64 | 65.5 | 67 | 60 | 62 | 66 | 58 |
| T.Str.，psi3 | 6320 | 3325 | 3450 | 3661 | 3649 | 3556 | 1880 | 2972 | 3202 | 2215 | 1922 | 2318 |
| ％Elong.4 | 551 | 930 | 760 | 785 | 687 | 642 | 579 | 703 | 816 | 581 | 474 | 687 |
| 100％Mod.，psi5 | 763 | 506 | 610 | 665 | 625 | 636 | 390 | 586 | 612 | 696 | 454 | 573 |
| 200％Mod.，psi6 | 1040 | 729 | 860 | 926 | 893 | 917 | 586 | 834 | 828 | 992 | 705 | 800 |
| 300％Mod.，psi7 | 1430 | 952 | 1120 | 1180 | 1180 | 1237 | 822 | 1098 | 1040 | 1257 | 1015 | 1025 |
| 400％Mod，psi8 | 2096 | 1190 | 1400 | 1463 | 1521 | 1653 | 1119 | 1415 | 1212 | 1552 | 1453 | 1266 |
| Die C Tear，pli9 | 374 | 389 | 400 | 402 | 259 | 269 | 273 | 375 | 419 | 204 | 169 | 417 |
| ％Comp.Set10 | 25.5 | 16.0 | -- | 16.1 | 20.8 | 21.8 | 35.0 | 17.7 | 17.1 | 25.3 | 17.7 | 13.0 |
| Taber Abr.11 | 52.3 | 182.7 | 151.0 | 97.4 | 97.3 | 88.5 | 101.1 | 78.4 | 110.1 | 144.6 | 210.1 | 171.1 |
| Comp.Defl.5％，psi12 | 138 | 68 | -- | 107 | 116 | 96 | 83 | 90 | 102 | 136 | 75 | 103 |
| Comp.Defl.10％，psi13 | 289 | 167 | -- | 221 | 246 | 207 | 177 | 195 | 218 | 278 | 166 | 220 |
| Comp.Defl.15％，psi14 | 441 | 267 | -- | 334 | 375 | 323 | 276 | 303 | 331 | 414 | 261 | 338 |
| Comp.Defl.25％，psj15 | 776 | 493 | -- | 582 | 662 | 586 | 503 | 550 | 583 | 711 | 486 | 606 |
As can be seen from tables 1A and 1B, comparative example C-2 shows that when a low monol polyoxypropylene diol having a molecular weight of 4000 is used as the sole polyol, the elastomer prepared is softer than when PTMEG-2000 alone (example C-1). The properties of the C-2 elastomer are also lower modulus, poor abrasion resistance, low compression set (load). The elastomer prepared from the composition of example C-2 was also found to have poor green strength during the chain extension process.
In order to improve the quality of elastomers prepared from low monol polyoxyalkylene glycols, a mixture of low monol content diols having a molecular weight of 4000 and PTMEG-2000 was used in comparative example C-3. Although the shore a hardness of the elastomers prepared with such mixtures is increased, the abrasion resistance is still unacceptable. PTMEG-2000 used in large quantities in this formulation is expensive and commercial use of this mixture is unattractive.
Mixtures of low monol content polyoxyalkylene glycols and low molecular weight polyols were also tested to determine whether the inclusion of low molecular weight polyols could improve the physical properties of elastomers made from the mixtures. When the polydispersity index (as determined by gel permeation chromatography) of the low molecular weight polyol used is less than 1.1 (see comparative examples C-5, C-6 and C-7), the resulting elastomers have low tensile strength and abrasion resistance. In addition, some of the elastomers (examples C-5 and C-6) had poor tear strength.
When a low molecular weight polyol having a broad molecular weight distribution (i.e., a polydispersity index greater than 1.1) is used with a low monol content polyoxyalkylene diol (see examples 1-5), the resulting elastomer has improved hardness, modulus, compression set, tensile strength, and abrasion resistance. The workability depending on the green strength is also greatly improved.
In examples 1-3 and comparative example C-4, a diol with a low monool content of molecular weight 4000 was used as the high molecular weight polyol. In this high molecular weight polyol, the random internal oxyethylene moieties are present in varying percentages, from 0% (example 1) to 15% (example 2) to 30% (example 3) to 40% (example C-4). Polyol I (polydispersity index about 1.6) was also used in examples 1, 2,3 and C-4 as a low molecular weight polyol. The properties of these elastomers are reported in Table 1B, and it is evident that the use of high molecular weight polyols containing 40% random internal oxyethylene moieties reduces the mechanical properties of the elastomers, such as tensile strength, elongation, modulus and compression set.
In example 4, a diol of 3000 molecular weight, low monol content containing 10% random internal oxyethylene moieties was used in combination with a sufficient amount of polyol I, and the resulting mixture had an average molecular weight of 2000 daltons. In example 5, an 50/50 mixture of a low monol content diol having a molecular weight of 3000, a 10% random internal oxyethylene moiety and a low monol content polyoxypropylene diol having a molecular weight of 8000 daltons was used as the high molecular weight portion of the polyol component. Elastomers prepared from such high molecular weight, low monol content polyols and low molecular weight polyols having a polydispersity index greater than 1.1 have excellent properties and processing characteristics. The abrasion resistance of the elastomers prepared in examples 4 and 5 is particularly good.
Examples 6 to 9 and comparative examples C-8 to C-13
The isocyanate-terminated prepolymer was prepared as in examples 1-5 and C-1-C-7 and then chain extended to form an elastomer. However, the prepolymer used in examples 6-9 and C-8-C-13 had an NCO content of 8%. Some specific materials for preparing these elastomers are listed in table 2A. The properties of the elastomers prepared in these examples are set forth in Table 2B.
TABLE 2A
| Examples/materials | C-8 | C-9 | 6 | 7 | C-10 | 8 | C-11 | C-12 | C-13 | 9 |
| Polyol A pbw | 100 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Polyol F pbw | --- | --- | --- | --- | --- | 86.62 | --- | --- | --- | 80.2 |
| Polyol B pbw | --- | 100 | 80.76 | --- | --- | --- | 93.52 | 82.4 | 80.6 | --- |
| Polyol M pbw | --- | --- | --- | 80.6 | --- | --- | --- | --- | --- | --- |
| Polyol E pbw | --- | --- | --- | --- | 80.6 | --- | --- | --- | --- | --- |
| Polyol H pbw | --- | --- | --- | --- | --- | --- | --- | 17.6 | --- | --- |
| Polyol I pbw | --- | --- | 19.24 | 19.4 | 19.4 | 13.38 | --- | --- | --- | --- |
| Polyol J pbw | --- | --- | --- | --- | --- | --- | --- | --- | 19.4 | --- |
| Polyol K pbw | --- | --- | --- | --- | --- | --- | --- | --- | --- | 19.8 |
| Polyol L pbw | --- | --- | --- | --- | --- | --- | 6.48 | --- | --- | --- |
| Mw/MnOf low molecular weight polyols | --- | --- | 1.6 | 1.6 | 1.6 | 1.6 | 1.1 | 1.01 | 1.1 | 1.65 |
| BDO，pbw | 12.1 | 11.4 | 12.1 | 12.1 | 12.1 | 12.1 | 12.1 | 12.1 | 12.1 | 12.5 |
| ISO，pbw | 47.7 | 39.5 | 47.7 | 47.7 | 47.7 | 47.7 | 47.7 | 47.7 | 47.7 | 50.0 |
| NCO/OH | 3.87 | 6.22 | 3.87 | 3.83 | 3.83 | 3.87 | 3.83 | 3.83 | 3.83 | 3.50 |
| ％NCO | 8.00 | 8.00 | 8.00 | 8.00 | 8.00 | 8.00 | 8.00 | 8.00 | 8.00 | 8.00 |
| Average molecular weight of the mixture | 2000 | 4000 | 2000 | 2000 | 2000 | 2000 | 2000 | 2000 | 2000 | 1750 |
TABLE 2B
| examples/Properties | C-8 | C-9 | 6 | 7 | C-10 | 8 | C-11 | C-12 | C-13 | 9 |
| Hardness，Shore A1 | 90 | 85 | 89 | 90 | 88 | 86 | 90 | 85 | 89.5 | 88 |
| ％Rebound2 | 64 | 64 | 60 | 58.5 | 59.5 | 61 | 59 | 66 | 53 | 51 |
| Tensile Strength，psi3 | 6921 | 3107 | 3821 | 3986 | 2968 | 3681 | 2813 | 2584 | 3244 | 3959 |
| ％Elong.4 | 581 | 865 | 766 | 674 | 616 | 692 | 579 | 566 | 793 | 600 |
| 100％Mod.，psi5 | 1083 | 777 | 1019 | 958 | 749 | 911 | 991 | 830 | 893 | 962 |
| 200％Mod.，psi6 | 1450 | 1051 | 1331 | 1277 | 1013 | 1224 | 1370 | 1203 | 1186 | 1340 |
| 300％Mod.，psi7 | 1955 | 1296 | 1614 | 1605 | 1308 | 1525 | 1668 | 1576 | 1430 | 1717 |
| 400％Mod.，psi8 | 2820 | 1542 | 1923 | 2001 | 1685 | 1871 | 1980 | 1973 | 1671 | 2181 |
| Die C Tear，pli9 | 414 | 474 | 537 | 404 | 332 | 490 | 234 | 216 | 379 | 362 |
| ％Comp.Set10 | 19 | 16 | 19 | 18.4 | 17.8 | 17 | 25 | 10.0 | 15.1 | ND* |
| Taber Abr11 | 61 | 208.3 | 146 | 101.8 | 109.7 | 109.1 | 204.2 | 203.8 | 194.6 | 91.2 |
| Comp.Defl.5％，psi12 | 212 | 141 | 189 | 225 | 171 | 143 | 237 | 139 | 236 | 166 |
| Comp.Defl.10％，psi13 | 454 | 322 | 392 | 451 | 353 | 327 | 456 | 289 | 448 | 362 |
| Comp.Defl.15％，psi14 | 673 | 483 | 570 | 648 | 520 | 499 | 647 | 433 | 634 | 549 |
| Comp.Defl.25％，psi15 | 1149 | 832 | 935 | 1048 | 865 | 857 | 1053 | 760 | 1027 | 948 |
1-15The meanings are the same as those in Table 1B
*Not determined ND
Higher NCO content prepolymers typically produce harder elastomers. Polyol A produced a prepolymer formed into an elastomer (example C-8) having a Shore A hardness of 90. The prepolymer formed elastomer (example C-9) prepared with polyol B alone (i.e., no PTMEG) was softer than example C-8 and had lower modulus, poor abrasion resistance, and low compression set (load). Although the elastomer prepared in example C-8 was prepared from a prepolymer having a higher NCO content, the tensile strength was still 7% lower than that of the elastomer prepared in example C-2, which demonstrates the disadvantage of using only high molecular weight polyols such as polyol A.
In contrast, elastomers prepared with polyol components containing high molecular weight, low monol content polyoxyalkylene glycols and low molecular weight polyols having a polydispersity index greater than 1.1 have greatly improved mechanical properties and processing characteristics.
In examples 6, 7 and comparative example C-10, a low monol content diol having a molecular weight of 4000 and an internal oxyethylene moiety content of 0% (example 6), 20% (example 7) or 40% (example C-10) was used as the high molecular weight polyol. Polyol I is also used in these examples as a low molecular weight polyol. As is evident from Table 2B, the elastomers prepared in examples 6 and 7 have better hardness, tensile strength, modulus, abrasion resistance and compression set properties than the elastomers prepared in comparative examples C-9. In comparative example C-10, the mechanical properties of the elastomers prepared with the high molecular weight polyols having an internal oxyethylene moiety content of more than 30% are inferior to those of the elastomers of examples 6 and 7, in particular tensile strength, elongation, modulus, tear strength and compression set.
In example 8, the high molecular weight polyol component used was a low monol diol containing 10% random internal oxyethylene moieties and having a molecular weight of 3000. Sufficient polyol I was mixed with this high molecular weight polyol (polyol F) to give an overall average molecular weight of 2000 daltons. Although the molecular weight decreased from 3000 to 2000 daltons after mixing, the resulting elastomer was slightly soft, the elastomer prepared using the polyol component obtained from this mixture had excellent tensile strength, tear strength and abrasion resistance.
Comparative examples C-11, C-12 and C-13 illustrate that the performance and processing characteristics of the elastomers produced using low molecular weight polyols having low dispersion indices (i.e., polydispersity indices of 1.1 or less) are unacceptable. The elastomers prepared in comparative examples C-11, C-12 and C-13 have low tensile strength and poor abrasion resistance.
In example 9, the polyol component contained low molecular weight polypropylene glycol having a polydispersity index of 1.65 (polyol K) and a low unsaturation high molecular weight polyol (polyol F). The polyol component produces elastomers having excellent tensile strength, abrasion resistance and other properties.
The foregoing detailed description of the invention has been presented for purposes of illustration, it being understood that the detailed description is for that purpose only and that variations may be made by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.
Claims (32)
1. A polyol composition having a number average molecular weight of from about 1,000 to 3,000 daltons, comprising:
(1) at least 60% by weight of a polyoxypropylene polyol having a molecular weight of about 2000 to 12,000 daltons, an internal or block/random oxyethylene moiety content of no more than 30% and an unsaturation of less than or equal to 0.02meq/g and
(2) from 5% to 40% by weight of a polyol having a molecular weight of from about 400 to 1,000 daltons and a polydispersity index greater than 1.1.
2. The polyol composition of claim 1, wherein the polydispersity index of the polyol (2) is greater than or equal to 1.3.
3. The polyol composition of claim 1, wherein the polydispersity index of the polyol (2) is greater than or equal to 1.6.
4. The polyol composition of claim 1, wherein the content of the polyol (1) is from 70 to 85% by weight.
5. The polyol composition of claim 1 having an average molecular weight of about 2,000 daltons.
6. The polyol composition of claim 1 wherein the number average molecular weight of polyol (1) is from about 3,000 to about 8000 daltons.
7. The polyol composition of claim 1 wherein the number average molecular weight of polyol (1) is from about 3000 to about 6,000 daltons.
8. The polyol composition of claim 1 wherein the unsaturation of polyol (1) is less than 0.010 meq/g.
9. The polyol composition of claim 1 wherein the polyol (1) has an unsaturation of less than 0.007 meq/g.
10. The polyol composition of claim 1 further comprising up to 20 weight percent of a triol, based on the total weight of the polyol, the triol having a number average molecular weight of from about 250 to 7,000 daltons.
11. The polyol composition of claim 10 wherein the triol is selected from propoxylates of glycerol and trimethylolpropane and ethylene oxide/propylene oxide copolymers of glycerol and trimethylolpropane.
12. An NCO-terminated prepolymer or quasi-prepolymer having an NCO content of about 3 to 20% which is the reaction product of a) and b),
a) di-or polyisocyanates and
b) the polyol composition of claim 1.
13. The prepolymer of claim 12, wherein the diisocyanate or polyisocyanate is 4, 4' -diphenylmethane diisocyanate or an isomeric mixture thereof.
14. The prepolymer of claim 12, wherein the diisocyanate or polyisocyanate is toluene diisocyanate, isophorone diisocyanate, or 1, 4-cyclohexane diisocyanate.
15. The prepolymer of claim 12, wherein the diisocyanate or polyisocyanate is a urea-modified isocyanate, a urethane-modified isocyanate, a carbodiimide-modified isocyanate, an allophanate-modified isocyanate, a biuret-modified isocyanate or an allophanate-modified isocyanate.
16. The prepolymer of claim 12, wherein the number average molecular weight of polyol (1) is from about 3,000 to about 8,000 daltons.
17. The prepolymer of claim 12 wherein the number average molecular weight of polyol (1) is from about 3000 to about 6,000 daltons.
18. The prepolymer of claim 12 wherein the unsaturation of the polyol (1) is less than 0.010 meq/g.
19. The prepolymer of claim 12 wherein the polyol (1) has an unsaturation of less than 0.007 meq/g.
20. The prepolymer of claim 12 wherein the polyol component further comprises up to 20 weight percent of a triol, based on the total weight of the polyol component, the triol having a number average molecular weight of from about 250 to 7,000 daltons.
21. The prepolymer of claim 12 wherein the polyol component further comprises up to 20 weight percent, based on the total weight of the polyol component, of a triol having a number average molecular weight of up to about 7,000 daltons selected from propoxylates of glycerol and trimethylolpropane and ethylene oxide/propylene oxide copolymers of glycerol and trimethylolpropane.
22. The prepolymer of claim 12 wherein the diisocyanate or polyisocyanate is 4, 4' -diphenylmethane diisocyanate and the polyol component comprises 60 to 95 weight percent polyoxypropylene polyol and 5 to 40 weight percent polytetramethylene ether glycol.
23. The prepolymer of claim 22 wherein up to 20 weight percent of the polyol component is a triol having a molecular weight of about 250 to 7,000 daltons.
24. A polyurethane comprising the reaction product of the prepolymer of claim 12 and a chain extender or crosslinker.
25. A polyurethane comprising the reaction product of the prepolymer of claim 22 and a chain extender or crosslinker.
26. A polyurethane comprising the reaction product of the prepolymer of claim 12 and a glycol chain extender.
27. A polyurethane comprising the reaction product of the prepolymer of claim 22 and butanediol.
28. A polyurethane comprising the reaction product of the prepolymer of claim 12 and butanediol.
29. An elastomer prepared by reacting (a), (b) and (c),
(a) an NCO-terminated prepolymer or quasi-prepolymer which is the reaction product of (1) and (2),
(1) di-or polyisocyanates and
(2) a polyoxypropylene polyol having a molecular weight of about 2000 to 12,000 daltons, an internal or block/random oxyethylene moiety content of no more than 30% and an unsaturation of less than or equal to 0.02meq/g and
(b) a polyol having a molecular weight of about 400 to 1,000 daltons, a polydispersity index greater than 1.1 and
(c) chain extender
The respective contents being such that the elastomer contains from 60 to 95% by weight of polyol (2) and from 5 to 40% by weight of polyol (b).
30. A one-step process for preparing a polyurethane elastomer which is the reaction product of a) and b),
a) di-or polyisocyanates and
b) the polyol composition of claim 1
The isocyanate index is from 70 to 130.
31. A one-step process for preparing a polyurethane elastomer which is the reaction product of (a) and (b),
(a) an isocyanate-terminated quasi-prepolymer prepared from a single part of the polyol composition of claim 1 and
(b) the remainder of the polyol composition of claim 1
The isocyanate index is from 70 to 130.
32. A one-step process for preparing a polyurethane elastomer comprising
(1) Introducing (a) and (b) into a vessel
(a) A first stream comprising the polyol composition of claim 1 and a chain extender
(b) Second stream containing di-or polyisocyanates
(2) The contents of the container are allowed to react.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US10/094238 | 2002-03-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| HK1056568A true HK1056568A (en) | 2004-02-20 |
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