NITRILO (TRIS) POLYOXYALKYLENEAMINES IN A REACTION INJECTION MOLDING PROCESS

Abstract: The invention is an amine terminated polyether of the formula: N-[(CH₂CH(CH₃)O) x -CH₂CH(CH₃)NH₂]₃ of 3000 to 7000 molecular weight. The polyamines are particularly suited for reaction with isocyanates to manufacture articles such as automobile body panels by reaction injection molding (RIM).

Description: The invention relates to a compound of the formula: N-[(CH₂CH(R₁)O) x -(AO) y -CH₂CH(R₂)NH₂]₃ wherein: R₁ is a methyl or ethyl radical, R₂ is hydrogen or R₁, A is an alkylene radical, x is 1 or greater, and x + y ranges from 2 to 40. These polyamines are particularly suited for reaction with isocyanates to manufacture articles by a Reaction Injection Molding (RIM) process. Reaction Injection Molding (RIM) is a technique for the rapid mixing and molding of large, fast curing urethane parts. RIM polyurethane parts are used in a variety of exterior body applications on automobiles where their light weight contributes to energy conservation. RIM parts are generally made by rapidly mixing active hydrogen-containing materials with polyisocyanate and placing the mixture into a mold where reaction proceeds. After reaction and demolding, the parts may be subjected to an additional curing step which comprises placing the parts in an oven, held at 121°C (250°F) or higher. The amination of long alkoxylated alkyl chains terminated by hydroxyl groups is well known in the art. US-A-3 654 370 teaches the amination of polyoxyalkylene polyols to form the corresponding amines by means of ammonia and hydrogen over a catalyst-prepared by the reduction of a mixture of the oxides of nickel, copper and chromium. The amination is carried out at a temperature of 150° to 275°C and 3.55 to 34.6 MPa (500 to 5000 psig). US-A-4 409 399 teaches a catalyst for aminating aliphatic alcohols and aldehydes. The unsupported catalyst comprises (1) copper oxide or copper hydroxide and (2) nickel oxide or nickel hydroxide, and optionally (3) an oxide or hydroxide of a Group IIA, e.g. magnesium, barium. The reaction is carried out at a temperature of 150° to 250°C and 0.1 to 10.1 MPa (1 to 100 atm) with continuous water removal. US-A-3 390 184 teaches a process for converting a secondary alcohol to a high molecular weight primary amine by means of a hydrogenation-dehydrogenation catalyst comprising at least one member selected from the group consisting of the metals and oxides of nickel and cobalt, together with copper and a metal oxide selected from the group consisting of chromium oxide, molybdenum oxide, manganese oxide and thorium oxide. The reaction is carried out at a temperature of 225° to 260°C and pressure of 13.9 to 27.7 MPa (2000 to 4000 psig), with ammonia as the aminating agent. US-A-3 373 204 teaches a catalytic process for producing secondary amines from derivatives of phenols, alcohols and amines containing 5 to 40 moles of ethylene oxide and propylene oxide. The catalyst is Raney nickel and ammonia or primary alkylamines as the aminating agent. The reaction is carried out at 200° to 275°C with the evolution of water. Amines include lauryl amine, hexadecyl amine, octadecyl amine, rosin amine and fatty acid amines. US-A-3 347 926 teaches a catalytic process for aminating primary and secondary aliphatic alcohols. The catalyst comprises a chromium promoted Raney nickel. The reaction is carried out at 150°C to 275°C with ammonia, primary amines or secondary amines of 1 to 6 carbon atoms. US-A-2 923 696 teaches resinous compositions formed by the reaction of an epoxy resin with a high boiling amine product. The patent further teaches hydrogenation catalysts employing copper, nickel, cobalt and oxides thereof. US-A-4 130 590 teaches the production of long chain unsaturated amines such as N-(alkadienyl)amines and saturated or hydrated derivatives thereof. The invention provides a compound of the formula: N-[(CH₂CH(R₁)O) x -(AO) y -CH₂CH(R₂)NH₂]₃ wherein: R₁ is a methyl or ethyl radical, R₂ is a hydrogen, methyl or ethyl radical, A is an alkylene radical selected from the group consisting of ethylene, propylene, butylene and mixtures thereof, x is 1 or greater and x + y ranges from 2 to 40. These amine terminated polyethers are particularly useful when reacted with a polyisocyanate in a reaction injection molding (RIM) process. The invention therefore also provides a RIM process in which ingredients comprising the amine terminated polyether, a diamine chain extender and a polyisocyanate are reacted in a closed mold to produce articles such as automobile body panels. An object of this invention is to produce RIM polyurethane parts with superior properties. It was surprisingly discovered that the polyamines defined above could be prepared by aminating hydroxyl terminated polyether initiators in a process which yielded higher conversion of hydroxyl to amino groups than the glycerine initiated analog. RIM elastomers are typically made by reacting a polyamine, a chain extender and a polyisocyanate together in a mold. Optional additives include catalysts, filler materials, mold release agents and the like. In this case, the polyamine component of the RIM elastomer is the nitrilo(tris) polyoxyalkyleneamine defined above. The amine terminated polyethers useful in a RIM process have a molecular weight of at least 500, and preferably at least 3000. Those polyether amines based on the instant nitrilo(tris) polyoxyalkyleneamine of 3000 to 7000 molecular weight are especially preferred. The polyethers may be prepared from ethylene oxide, propylene oxide, butylene oxide or mixtures of propylene oxide, butylene oxide and/or ethylene oxide. The polyethers are aminated as described in US-A-3 654 370 which describes the amination of polyoxyalkylene polyols to form the corresponding amines. The amination is catalyzed by a catalyst prepared from a mixture of the oxides of nickel, copper and chromium in the presence of ammonia and hydrogen at 150° to 275°C and 3.5 to 34.6 MPa (500 to 5000 psig). It has been discovered that polyether polyols can be reductively aminated provided the amine is sterically hindered. Hindrance of the tertiary amine stabilises the molecule, preventing cleavage of the hindered tertiary amine by the metallic catalyst. In the instant invention, the tertiary amine is hindered by surrounding it with sterically bulky alkyl groups attached to alkylene oxide molecules. If the tertiary amine were not hindered, the polyether chains are cleaved at the nitrogen atom, yielding a variety of decomposition products rather than the triamine. The chain-extenders useful in the process of this invention are preferably difunctional. Mixtures of difunctional and trifunctional chain-extenders are also useful in this invention. The chain-extenders useful in this invention include diols, amino alcohols, diamines or mixtures thereof. Low molecular weight linear diols such as 1,4-butanediol and ethylene glycol have been found suitable for use in this invention. Ethylene glycol is especially preferred. These chain-extenders produce a polymer having a high glass transition temperature and/or high melting points when reacted with a suitable diisocyanate. It has been discovered that the polyurethane polymers produced according to this invention which have a high glass transition temperature and a high melting point also show the improved properties in the process of this invention. Other chain-extenders including cyclic diols such as 1,4-cyclohexane diol and ring containing diols such as bis-hydroxyethylhydroquinone, amide or ester containing diols or amino alcohols, aromatic diamines and aliphatic amines are also suitable as chain-extenders in the practice of this invention. The polyisocyanate used to react with the nitrilo(tris) polyoxyalkylene amine initiators may be aromatic or aliphatic polyisocyanate. Typical aromatic polyisocyanates include p-phenylene diisocyanate, polymethylene polyphenylisocyanate, 2,6-toluene diisocyanate, dianisidine diisocyanate, bitolylene diisocyanate, napthalene-1,4-diisocyanate, bis(4-isocyanatophenyl)methane, bis(3-methyl-3-isocyantophenyl)methane, bis(3-methyl-4-isocyanatophenyl)methane, and 4,4'-diphenylpropane diisocyanate Other aromatic polyisocyanates used in the practice of the invention are methylene-bridged polyphenyl polyisocyanate mixtures which have a functionality of from 2 to 4. These isocyanate compounds are produced by the phosgenation of corresponding methylene bridged polyphenyl polyamines, which are conventionally produced by the reaction of formaldehyde and primary aromatic amines, such as aniline in the presence of hydrochloric acid and/or other acidic catalysts. Known processes for preparing polyamines and corresponding methylene-bridged polyphenyl polyisocyanates therefrom are described in US-A-2 683 730, -2 950 263, -3 012 008, -3 344 162 and -3 362 979. Usually methylene-bridged polyphenyl polyisocyanate mixtures contain 20 to 100 wt% methylene diphenyldiisocyanate isomers, with the remainder being polymethylene polyphenyl diisocyanates having higher functionalities and higher molecular weights. Typical of these are polyphenyl polyisocyanate mixtures containing 20 to 100 wt% methylene diphenyldiisocyanate isomers, of which 20 to 95 wt% thereof is the 4,4'-isomer with the remainder being polymethylene polyphenyl polyisocyanates of higher molecular weight and functionality that have an average functionality of from 2.1 to 3.5. These isocyanate mixtures are commercially available and can be prepared by the process described in US-A-3 362 979. The most preferred aromatic polyisocyanate is methylene bis(4-phenylisocyanate) or MDI. Pure MDI, quasi- prepolymers of MDI, modified pure MDI, are all useful in the preparation of RIM elastomers. Since pure MDI is a solid and thus, often inconvenient to use, liquid products based on MDI are often used and are included in the scope of the terms MDI or methylene bis(4-phenylisocyanate) used herein. US-A-3 394 164 is an example of a document disclosing a liquid MDI product. More generally uretonimine modified pure MDI is included also. This product is made by heating pure distilled MDI in the presence of a catalyst to give a mixture of pure MDI and modified MDI. Preferably, the amount of isocyanates used is the stoichiometric amount based on all the ingredients in the formulation or greater than the stoichiometric amount. Examples of commercial materials of this type are Upjohn's Isonate® 125M (pure MDI) and Isonate® 143L (liquid MDI). Although not essential for the practice of this invention, additives which enhance the color or properties of the polyurethane elastomer may be used. For example, chopped or milled glass fibers, chopped or milled carbon fibers and/or other mineral fibers are useful. The RIM polyurethane elastomers of this invention are made in the conventional manner in a mold and are then post cured at temperatures of 121 to 218°C (250°F to 425°F) and preferably 154 to 177°C (310°F to 350°F). Another type of additive which may be required as post curing temperatures approach 204°C (400°F) or more is an antioxidant. The materials which are well known to those skilled in the art include hindered phenols. The following examples demonstrate our invention. EXAMPLE 1 Preparation of the 5100 Molecular Weight Propylene Oxide Adduct of Triisopropanolamine (TIPA) To a 40 litre (ten-gallon) kettle were charged 2.27 Kg (5 lb.) of a 657 molecular weight propylene oxide adduct of TIPA and 151.2g of 45% aqueous potassium hydroxide. The reactor was then purged with nitrogen and heated to 100°C. The initiator was then dried, with vacuum and nitrogen to a water content of less than 0.1%. Propylene oxide in an amount of 20.1 Kg (44.3 lb) was then reacted at 105-110°C at 0.44 MPa (50 psig). Approximately 8.4 hours was required for addition of the propylene oxide. The reaction mixture was then digested two hours to equilibrium pressure. The alkaline product was neutralized by stirring two hours with 408g magnesium silicate added as an aqueous slurry. Di-t-butyl p-cresol (22.4g) was then added to stabilize the polyol. The neutralized polyol was vacuum stripped to a minimum pressure, nitrogen stripped, and filtered. The finished product had the following properties. Hydroxyl no., mg KOH/g 32.5 Water, wt% 0.02 Unsaturation, meq/g 0.055 pH in 10:6 isopropanol/water 9.3 Viscosity, mm²/s 25°C (77°F) 1051 38°C (100°F) 621 Total amine, meq/g 0.16 Tertiary amine, meq/g 0.16 EXAMPLE 2 Reductive Amination of ∼5000 Molecular Weight Polyol Using A Nickel Catalyst A 1-liter stirred autoclave was charged with 605g of a 5100 mol wt. propylene oxide adduct of triisopropanolamine of Example 1, with 65.001g of a powdered, supported 47 wt% nickel catalyst, and with 74.7g of NH₃ in a hydrogen atmosphere. The pressure in the autoclave was increased to 2.5 MPa (350 psig) with hydrogen (at 28°C). The temperature was raised to 243.1°C at 13.65 MPa (1965 psig) during a 60-minute period. It was maintained at 241.5° to 247.3°C (average ∼245°C) for 30 minutes. It was then cooled rapidly to room temperature 1.17 MPa (155 psig) at 26°C. The contents of the autoclave were filtered, and the filtrate was stripped on a rotary evaporator at 99°C at 667 Pa (5 mm Hg). Analyses indicated: Measured Theoretical 0.583 meq/g total acetylatables 0.58 0.54 meq/g total amines 0.74 0.47 meq/g primary amines 0.58 0.16 meq/g tertiary amines 0.16 The high degree of conversion with complete retention of tertiary amine functionality was noteworthy. EXAMPLE 3 Preparation of a 5000 Molecular Weight Product insing Mo-Promoted Raney Ni Catalyst The procedure of Example 2 was repeated, except the catalyst was 60.02g of anhydrous Raney 3100 (from W. R. Grace & Co.). The quantities of polyol and NH₃ were 695.6 and 52.95g, respectively, initial pressure was 3.93 MPa (555 psig) at 32.0°C, heat up time was 45 minutes, and average temperature was 246°C for 13 minutes. Analyses of the stripped and filtered product was as follows: Total acetylatables = 0.595 meq/g Total amines = 0.62 meq/g Primary amines = 0.45 meq/g Tertiary amines = 0.15 meq/g Again, the nearly complete retention of tertiary amine functionality was noteworthy. EXAMPLE 4 Preparation of Product Using Ni/Cu/Cr Catalyst Example 2 was repeated, except that the catalyst was 75.01g of the powdered Ni/Cu/Cr catalyst of US-A-3 654 370, (Harshaw Ni-2715 catalyst). Initial pressure was 3.36 MPa (473 psi), and average reaction temperature was 248°C. It yielded product with the following analyses: Total acetylatables 0.574 meq/g Total amines 0.41 meq/g Primary amines 0.25 meq/g Tertiary amines 0.16 meq/g EXAMPLE 5 (Comparative) Amination of Polypropoxylated Triethanolamine The procedure of Example 3 was repeated except the polyol was a polypropoxylated triethanolamine with the following analyses: Total acetylatables 0.549 meq/g Total amines 0.16 meq/g Tertiary amines 0.15 meq/g After conducting the reaction as in Example 3 (at 245°C avg. operating temperature and 3.53 MPa (497 psig) initial pressure), the filtered and stripped product had the following analyses: Total acetylatables 0.797 meq/g Total amines 0.75 meq/g Primary amines 0.66 meq/g Tertiary amines 0.04 meq/g The essentially complete destruction of the tertiary amine functionality with concomitant increase in total acetylatable and secondary amine (calculated by difference to be 0.05 meq/g) was noteworthy. EXAMPLE 6 Continuous Preparation of Product Using Cr-promoted Raney Ni Catalyst A 100 cm³ tubular reactor was charged with 1.0-1.23 mm (6 x 8 mesh) chromium-promoted Raney nickel. It was maintained at 13.9 MPa (2000 psig) while NH₃, H₂, and the polyol of Example 1 were simultaneously introduced at four sets of operating conditions. The hydrogen rate was 5 1/h. and the NH₃ concentration (as percent of total liquid weight) was 48-53% in each case. The conditions and results were the following: Run No. °C g/cm³/h Polyol Space Vel. Meq/g Total Acetylatables Total Amine Primary Amine Tertiary Amine 1 205 0.60 0.572 0.60 0.44 0.15 2 215 0.61 0.582 0.66 0.50 0.15 3 225 0.63 0.598 0.69 0.53 0.14 4 215 0.58 0.584 0.66 0.50 0.15 EXAMPLE 7 Continuous Preparation of Product Using Ni/Cu/Cr The procedure of Example 6 was repeated except that Ni/Cu/Cr catalyst of Example 4 was used in the form of tablets. Conditions and results are shown in Table 1. EXAMPLE 8 Use of Product in Polyurea RIM The product made in Example 7 (Product 6222-29-1) was used to produce polyurea RIM. The characteristics of the plastic elastomer made using this product are comparable or superior to those of the standard elastomers made from JEFFAMINE® T-5000, a polypropylene oxide triamine of about 5000 molecular weight. This product yields an elastomer which is characterized by a longer gel time and a higher green strength than the comparative product. Quasi-prepolymer A was prepared by reacting THANOL® SF-5505 a 5000 molecular weight, high reactivity triol (40 wt%) with ISONATE® 143L (60 wt%) EXAMPLE 8A Product 6222-29-1 (66.0 pbw), diethyltoluene diamine (DETDA) (34.0 pbw), and zinc stearate (1.58 pbw) were charged into the B-component working tank of an Accuratio VR-100 two-component RIM machine and heated to 93°C (200°F) for 30 minutes to dissolve the zinc stearate. The B-component tank was then cooled to 56°C (132°F). Quasi-prepolymer A (109.3 pbw) was charged into the A-component tank and the temperature of this component was adjusted to 53°C (127°F). The components were injected into the flat plaque mold measuring 460 x 460 x 3 mm (18-in. x 18-in. x 0.125-in) which had been preheated to 71°C (160°F). The part was removed from the mold in 30 seconds. The resulting elastomer was post cured at 150°C (311°F) for 60 minutes. Physical properties of the elastomer are shown in Table 2. The gel time of this material was determined to be 1.7 seconds. Processing of this formulation was very good. EXAMPLE 8B (Comparative) JEFFAMINE® T-5000 (66.0 pbw), DETDA (34.0 pbw) and zinc stearate (1.58 pbw) were charged into the B-component working tank of an Accuratio VR-100 two-component RIM machine and heated to 93°C (200°F) for 30 minutes to dissolve the zinc stearate. The B-component tank was then cooled to 57°C (135°F). Quasi-prepolymer A (108.0 pbw) was charged into the A-component tank and the temperature of this component was adjusted to 55°C (131°F). The components were injected into the flat plaque mold measuring 460 x 460 x 3 mm (18-in. x 18-in. x 0.125-in). which had been preheated to 71°C (160°F). The part was removed from the mold in 30 seconds. The resulting elastomer was post cured at 150°C (311°F) for 60 minutes. Physical properties of the elastomer are shown in Table 2. The gel time of this material was 1.6 seconds.

Claims: A compound of the formula: N-[(CH₂CH(R₁)O) x -(AO) y -CH₂CH(R₂)NH₂]₃ wherein: R₁ is a methyl or ethyl radical, R₂ is a hydrogen, methyl or ethyl radical, A is an alkylene radical selected from the group consisting of ethylene, propylene, butylene and mixtures thereof, x is 1 or greater and x + y ranges from 2 to 40. The compound of Claim 1 wherein x + y ranges from 20 to 30. A compound of claim 1 having the formula: N-[(CH₂CH(CH₃)O) x -CH₂CH(CH₃)NH₂]₃ wherein: x ranges from 2 to 40. The compound of Claim 3 wherein x ranges from 20 to 30. A reaction injection molding process comprising reacting in a closed mold, ingredients comprising an polyamine, an amine terminated chain extender and a polyisocyanate characterized by using as a polyamine the compound of the formula: N-[(CH₂CH(R₁)O) x -(AO) y -CH₂CH(R₂)NH₂]₃ wherein: R₁ is a methyl or ethyl radical, R₂ is a hydrogen, methyl or ethyl radical, A is an alkylene radical selected from the group consisting of ethylene, propylene, butylene and mixtures thereof, x is at least 1 and x + y selected so that the average molecular weight is at least 500. The process of Claim 5 wherein A is a propylene radical and R₁ and R₂ are both methyl. The process of Claim 5 wherein the molecular weight is at least 3000. The process of Claim 5 wherein the molecular weight is 3000 to 7000.

Inventors: CUSCURIDA, MICHAEL, LARKIN, JOHN MICHAEL
Applicants: TEXACO DEVELOPMENT CORPORATION
Application year: 1988
Main classification: C08G18
IPC codes: C07D303, C07C217, C08G18, C07C67, C08G65, C08G59, B29C45, C07C213, B29C39, B29K75