MXPA98004006A - Polyurethane catalyst compositions parametering performance of esp - Google Patents

Abstract

The present invention relates to a method for preparing a flexible polyurethane foam by reacting an organic polyisocyanate and a polyol in the presence of a blowing agent, a cell stabilizer and a catalyst composition, the improvement to control the latitude of processing the foam composition comprising using a catalyst composition which essentially consists of > 0 a < 100% mol of 3-dimethylaminopropyl urea and of > 0 a < 100% mol of N, N'-bis (3-dimethylaminopropyl) ur

Description

POLYURETHANE CATALYTIC COMPOSITIONS TO IMPROVE FOAM PERFORMANCE BACKGROUND OF THE INVENTION The present invention relates to tertiary amine catalysts, for producing polyurethane foam. Polyurethane foams are widely known and used in the automotive, home construction and other industries. These foams are produced by reaction of a polyisocyanate with a polyol, in the presence of various additives. Such an additive is a chlorofluorocarbon blowing agent (CFC) which evaporates as a result of the reaction exotherm, causing the polymerization mass to foam. The discovery that CFCs deplete the ozone layer in the stratosphere has produced regulations that reduce the use of CFCs. The production of water-blown foams, where blowing is carried out with C02 generated by the reaction of water with the polyisocyanate, has consequently become increasingly important. Tertiary amine catalysts are typically used to accelerate blowing (the reaction of water with isocyanate to generate C02) and gelation (the reaction of polyol with isocyanate). The ability of the tertiary amine catalyst to selectively promote either blowing or gelling is an important consideration in selecting a catalyst for the production of a particular polyurethane foam. If a catalyst promotes the blowing reaction to a very high degree, much of the C02 will be released before sufficient isocyanate reaction with polyol has occurred and the C02 will bubble away from the formulation, causing collapse of the foam. Poor quality foam will be produced. In contrast, if a catalyst promotes the gelation reaction too strongly, a substantial portion of CO 2 will be released after a significant degree of polymerization has occurred. Again, poor quality foam will be produced, this time characterized by high density cells, broken or poorly defined, or other undesirable characteristics. Tertiary amine catalysts generally have a bad odor and are offensive and many have high volatility due to low molecular weight. The release of tertiary amines during the foaming process can present significant safety and toxicity problems, and the release of residual amines from consumer products is generally undesirable. Amine catalysts containing urea functionality (e.g., RNHCONHR ^) have an increase in molecular weight and hydrogen bonds with reduced volatility and odor, when compared to related structures lacking this functionality. In addition, the catalysts containing urea functionality are chemically bound to the urethane during the reaction and do not detach from the finished product. The catalyst structures that incorporate this concept are typically of low to moderate activity and promote both blowing (isocyanate-water) and gelation (isocyanate-polyol) reactions in varying proportions. The patent of the U.S.A. No. 4,644,017 discloses the use of certain diffusion-stable amino alkyl ureas having tertiary amino groups in the production of a polyisocyanate addition product that does not discolor or change the constitution of the surrounding materials. Specifically illustrated are Catalyst A and catalyst D which are reaction products of dimethylaminopropylamine and urea. The patent of the U.S.A. No. 4,007,140 discloses the use of N, N'-bis (3-dimethylaminopropyl) urea as a low odor catalyst for the manufacture of polyurethanes. The patent of the U.S.A. No. 4,194,069 discloses the use of N- (3-dimethylaminopropyl) -N 1 - (3-morpholino-propyl) urea, N, N'-bis (3-dimethylaminopropyl) urea and N, N'-bis. { 3-morpholinopropyl) urea, as catalysts for producing polyurethanes. The patent of the U.S.A. No. 4No. 094,827 discloses the use of certain alkyl substituted ureas, including N, N'-bis (3-dimethylaminopropyl) urea which provide less odor and a delay in the foaming reaction, which contribute to the production of polyurethane foam. The patent of the U.S.A. No. 4,330,656 describes the use of N-alkyl ureas as catalysts for the reaction of 1,5-naphthylene diisocyanate with polyols or for the chain extension of prepolymers based on 1,5-naphthylene diisocyanates without accelerating atmospheric oxidation. DE 30 27 796 A1 discloses the use of dialkyl aminoalkyl ureas of higher molecular weight, as reduced odor catalysts, for the production of polyurethane foam. COMPENDIUM OF THE INVENTION The present invention provides a catalyst composition for producing flexible polyurethane foam. The catalyst composition comprises 3-dimethylaminopropyl urea and N, N'-bis (3-dimethylaminopropyl) urea, ie the mono- and bis-ureas of 3-dimethylaminopropylamine, respectively. By using these catalyst compositions, which comprise a mixture of the mono and bis alkyl substituted ureas in amounts from >; 0 a < 100% mole of mono urea and > 0 a < 100% mol of bis-urea, the physical properties of the polyurethane foam are improved. The proportion of the two urea compounds can be varied to systematically control the physical properties of fluidity, air flow, and force-to-crush so that the flexible foams improve their processability. Increasing the ratio of N, N'-bis (3-dimethylaminopropyl) urea to 3-dimethylaminopropyl urea increases the air flow and decreases the force-to-crush values of the foam, while reducing the N-ratio. , N'-bis (3-dimethylaminopropyl) urea to 3-dimethylaminopropyl urea improves the fluidity of the foam composition. An additional advantage of these catalysts is that they contain a ureido group which will react with isocyanate and chemically bind to the urethane during the reaction; therefore, the catalyst does not come off the finished foam product. DETAILED DESCRIPTION OF THE INVENTION The catalyst compositions according to the invention catalyze the reaction between an isocyanate functionality and an active hydrogen-containing compound, i.e. an alcohol, a polyol, an amine or water, especially the reaction of urethane (gelling) of polyol hydroxyl with isocyanate to produce polyurethanes and the reaction of blowing water with isocyanate, to release carbon dioxide to produce foamed polyurethanes. The flexible, plate and molded polyurethane foam products are prepared using any suitable organic polyisocyanates well known in the art, including for example, hexamethylene diisocyanate, phenylene diisocyanate, toluene diisocyanate ("TDI") and 4,4'-diphenyl methane diisocyanate ("MDI"). 2,4- and 2,6-TDI are particularly convenient individually or together as their commercially available mixtures. Other suitable isocyanates are mixtures of diisocyanates commercially known as "crude MDI", commercially available as PAPI from Dow Chemical, containing about 60% of 4,4'-diphenylmethane diisocyanate together with other isomeric polyisocyanates and higher analogues. Also suitable are "prepolymers" of these polyisocyanates comprising a partially pre-reacted mixture of a polyisocyanate and a polyether or polyester polyol. Illustrative of suitable polyols as components of the polyurethane composition are polyalkylene ether and polyester polyols. Polyalkylene ether polyols include poly (alkylene oxide) polymers such as polymers and copolymers of poly (ethylene oxide) and poly (propylene oxide) with terminal hydroxyl groups derived from polyhydric compounds, including diols and triols; for example, among others, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, pentaerythritol, glycerol, diglycerol, trimethylol propane and polyols of low molecular weight similar. In the practice of this invention, a single high molecular weight polyether polyol can be used. Also, mixtures of high molecular weight polyether polyols such as mixtures of di- and trifunctional materials and / or materials of different molecular weight or different chemical composition can be used. Useful polyester polyols include those produced by reacting a dicarboxylic acid with an excess of a diol, for example, adipic acid with ethylene glycol or butanediol, or reacting a lactone with an excess of a diol such as caprolactone with propylene glycol. In addition to polyether and polyester polyols, master batches or premix compositions often contain a polyol polymer. Polymer polyols are used in polyurethane foam to increase the foam deformation resistance, i.e. Increase the foam's load-bearing properties. Currently, two different types of polymer polyols are used to achieve load bearing improvement. The first type, described as a graft polyol, consists of a triol, wherein the vinyl monomers are graft copolymerized. Styrene and acrylonitrile are the usual monomers of choice. The second type, a polyurea modified by polyurea, is a polyol containing a polyurea dispersion formed by the reaction of a diamine and TDI. Since TDI is used in excess, some of the TDI can react with both the polyol and the polyurea. This second type of polyol polymer has a variant called polyol PIPA, which is formed by the in situ polymerization of TDI and alkanolamine in the polyol. Depending on the load bearing requirements, the polymer polyols may comprise 20 to 80% of the polyol portion of the masterbatch. Other typical agents found in polyurethane foam formulations include chain extenders such as ethylene glycol and butanediol; crosslinkers such as diethanolamine, diisopropanolamine, triethanolamine and tripropanolamine; blowing agents such as water, CFCs, HCFCs, HFCs, pentane and the like; and cell stabilizers such as silicones. A general formulation of polyurethane-based flexible foam having a density of 16 to 48 kg / m3 (1 to 3 lb / ft3) (eg, for automotive seats) contains a catalyst such as the catalyst composition according to the invention, will comprise the following components in parts by weight (pbw = parts by weight): Formulation of Flexible Foam pbw Polyol 20-100 Polyol Polyol 80-0 Silicone Surfactant 1 -2.5 Blowing Agent 2-4.5 Interleaver 0.5-2 Catalyst 0.2-2 Isocyanate Index 70-115 Reactive catalyst compositions comprise the compounds represented by the following formulas I and II, in any molar ratio, preferably 50 to 95% mol, of mono-urea (I), to control process latitude in a effective way in cost. % In mol is based on moles of mono-urea (I) and bis-urea (II). In order to improve the flowability of the foam composition, the catalyst composition should contain 80 to 95% mol of mono-urea (I) and 5 to 20% mol of bis-urea (II). To increase the air flow and decrease the force-to-crush values of the flexible foam, the catalyst composition should be 5 to 20% mol of mono-urea (I) and 80 to 95% mol of bis-urea (II). In addition, as a result of the preparation process, the catalyst composition may contain up to 20% by weight of unreacted urea (III), based on the weight of the compounds (I) and (II). 3-Dimethylaminopropyl urea N, N'-bis (3-dimethylaminopropyl) urea III Urea Compounds I and II are prepared by reacting urea and N, N-dimethylamino-propylamine in the appropriate molar proportions under an inert atmosphere at elevated temperatures. Compounds I and II can be isolated individually by chromatography techniques known in the art of synthesis.

A catalytically effective amount of the catalyst composition is employed in the polyurethane formulation. More specifically, convenient amounts of the catalyst composition may be in the range from about 0.01 to 10 parts by weight per 100 parts of polyol (pphp) in the polyurethane formulation, preferably 0.05 to 1 pphp. The catalyst composition can be used in combination with, or also comprise, other tertiary amine, organotin or urethane carboxylate catalysts well known in the urethane art. EXAMPLE 1 Synthesis of 3-Dimethylaminopropyl Urea (I) A molar ratio 94: 6 of catalyst mixture of 3-dimethylaminopropyl urea (I) and N, N'-bis (3-dimethylaminopropyl) urea (II) is prepared using a flask of round bottom with 3 necks and a liter capacity, adapted with the following: mechanical agitator, reflux condenser, nitrogen sparger, and temperature-controlled heating mantle. The flask was charged with 176.3 g of urea [CH4N20] and 300 g of N, N-dimethylaminopropylamine [(CH3) 2NHC2CH2CH2NH2]. The mixture is stirred at constant speed while slowly heating to 120 ° C. The reaction is monitored at 120 ° C until all signs of NH 3 evolution have ceased (as evidenced by bubbling in the N 2 pressure relief device). The pale yellow liquid is cooled to 80 ° C and the flask containing the liquid is evacuated by a vacuum pump and replenished with N2 three times, to remove any volatiles still present. Quantitative 13 C NMR showed that the product is 86% in mol of 3-dimethylaminopropyl urea (I), 5% in mol of N, N'-bis (3-dimethylaminopropyl) urea (II) and 9% in mol of unreacted urea . The molar ratio mono to bis is 17.2 to 1, or the 94: 6 ratio of mono urea to bis urea. EXAMPLE 2 Synthesis of N, N'-bis (3-dimethylaminopropyl) Urea (II) A round bottom flask with 3 necks and a liter capacity, was adapted with the following: mechanical stirrer, reflux condenser, nitrogen sparger, and controlled temperature heating mantle. The flask was charged with 83.96 g of urea [CH4N20] and 300 g of N, N-dimethylaminopropylamine [(CH3) 2NHC2CH2CH2NH2]. The mixture is stirred at constant speed while slowly heating to 120 ° C. The reaction is controlled at 120 ° C for 1.5 hours and then the reaction temperature is increased to 140 ° C, 160 ° C and finally 180 ° C. The temperature increases each time the release of ammonia is stopped. The excess of N, N-dimethylaminopropylamine was removed by distillation. Quantitative 13 C NMR showed that the product is 98% in mol of N, N'-bis (3-dimethylaminopropyl) urea (II) and 2% in mol of 3-dimethylaminopropyl urea (I). EXAMPLE 3 Synthesis in 53:47 molar ratio of 3-Dimethylaminopropyl Urea (I) and N mixture, N'-bis (3-dimethylaminopropyl) Urea (II) A mixture of 21.6 g of catalyst of Example 1 and 15.9 g of catalyst of Example 2, produces a mixture containing 51 mol% of I and 44 mol% of II and 5% in mol of unreacted urea. EXAMPLE 4 A flexible polyurethane foam is prepared in a conventional fashion in a 30.5 x 30.5 x 7.6 cm (12"xl2" x3") test block mold heated to 71 ° C (160 ° F) .The polyurethane formulation in parts by weight was: COMPONENT pbw E-648 60 E-519 40 DC-5043 0.6 Dietanolamine 0.2 Water 3.5 TDI 80 index 105 E-648 - a polyether polyol with a conventional ethylene oxide tip, marketed by Arco Chemical Co.

E-519 - a polyether polyol filled with styrene-acrylonitrile copolymer sold by Arco Chemical Co. DABCOE DC-5169 - silicone surfactant sold by Air Products and Chemicals, Inc. TDI 80 - a mixture of 80% by weight of 2 , 4-TDI and 20% by weight of 2,6-TDI. Table I lists the physical properties obtained using the catalysts of Examples 1 to 3. The foam tested met the standard specifications listed by ASTM D 3453-91 and the tests were performed using the designation ASTM D 3574-95. Strength-to-crush results were obtained by using a mechanical device equipped with a 454 kg (1000 lb.) pressure transducer mounted between the 323 cm2 (50 square inch) circular plate and the impulse shaft. The Dayton engine specifications, model 4Z528, include 1/6 horsepower (124 J / S) with F / L rpm of 1800 and torque F / L of 6.36xl04 Nm (5.63 in-lb). The current pressure is displayed on a digital display. The cushion is compressed to 50% of its original thickness and the force required to achieve compression is recorded. A cycle takes 24 seconds to complete and the current crush of the foam occurs in 7-8 seconds. This device mimics the "Indentation Forcé Deflection Test" test (ASTM D-3574) and provides a numerical value for 1 minute of initial hardness or softness of foam subsequent to demolding. Table I Catalyst Catalyst Catalyst of Example 1 of Example 2 of Example 3 Proportion Mono / Bis 94: 6 0: 100 53:47 pphpa 1.17 1.17 1.17 Density (lb / ft3; kg / m3) 1.95; 31.2 1.91; 30.6 1.9; 30.4 Air Flow (SCFM; L / min) 3.3; 93.4 3.71; 105.1 3.62; 102.5 Force-to-crush11 (lbf; N) 108; 479 65; 289 97; 431 % ILD (lbf; N) 23; 102 22; 98 23; 102 65% ILD (lbf; N) 61; 271 62; 275 62; 275 25% R ILD (lbf; N) 19; 84 18; 80 19; 84 Ball Rebound 51 55 52 50% Adjust Comp. (%) 26 33 31 50% Adjust Comp. HE HAS. 39 40 39 Japanese wet adjustment ± _ ___. 36 _____ to catalyst mixtures are diluted to 75% by weight in dipropylene glycol Lower force-to-crush values mean that the foam is more easily compressed. Example 4 demonstrates that increasing the levels of N, N'-bis (3-dimethylaminopropyl) urea (II) increases the air flow and decreases the physical strength-to-crush properties of the foam. This improves the latitude of processing and decreases shrinkage of the foam. EXAMPLE 5 A polyurethane foam is prepared in a conventional manner using the same formulation listed in Example 4. The catalyst (Table II) was added to 202 g of the premix in a paper cup of 951 ml (32 oz) and the formulation was mixed for 20 seconds at 5000 RPM using a top agitator adapted with a stirring blade with a diameter of 5.1 cm (2 in). TDI 80 was added to make a foam with index 105 [index (mol of NCO / mol of active hydrogen) x 100] and the formulation was mixed well for 5 seconds using the same top agitator. The 951 ml (32 oz.) Paper cup was dropped through a hole in the bottom of a 3,804 ml (128 oz.) Paper cup placed on a shelf. The hole was sized to trap the lip of the 951 ml (32 oz.) Paper cup. The total volume of the foam container was 4755 ml (160 oz.). The foams approached this volume at the end of the foaming process. Strength-to-crush data were obtained in Table II using a test block mold heated to 160 ° F (71 ° C) and crushing the foam 1 minute after mold release. Table II Catalipphp TOC 1 TOC 2 Gel Strength-to-cord-borne elevation Complete crush (s) (S) (S) (s) (lbf, N) Ex. 1 1.17 14.0 44.7 74.2 166.1 109; 484 Ex. 2 1.17 12.4 40.7 77.1 153.0 65; 289 Ei- 2 1.29 11.7 38.9 72.8 139.81 73; 324 The times mentioned were from mixing the polyol with isocyanate. The top of the cup 1 (TOC 1) represents the time required for the foam formulation to fill a 951 ml (32 oz.) Beaker and is an indication of the start of the reaction. The top of the beaker (TOC 2) represents the time required for the foam formulation to fill a 3.8 L 951 ml (128 oz.) Cuvette in addition to the aforementioned 951 ml (32 oz.) Beaker and is an indication of progress of the reaction. The Gel of the cord and complete elevation are additional measures of reaction advance and provide some indication of magnitude of cure. In Example 5, levels of catalyst use were chosen to adjust bead gel times. The gel times of the catalyst bead (II) of Example 2 at different use levels span the bead gel time of the catalyst (I) of Example 1 and are within the experimental error of the gel bead times of the catalyst ( I) of Example 1. The data in Table 2 indicate that the catalyst (I) of Example (I) provides an initial delay at the start of the reaction (longer TOC 1) while providing cure within the same time as the catalyst ( II) of Example 2. This initial delay allows greater foam fluidity and improves processing latitude. Table 3 of the U.S. patent No. 4,644,017 indicates that catalyst A and catalyst D provide equivalent performance for semi-rigid foam with thin-sheet PVC backing. Therefore, a person skilled in the art would not expect improvements in performance of the flexible foam using the mixtures of the catalysts (I) and (II). Unexpectedly, mixtures of the catalysts (I) and (II) provide performance improvements in flexible foam. The patent of the U.S.A. No. 4,007,140 Example 6 demonstrates that N, N'-bis (3-dimethylaminopropyl) urea (II) produces foam of superior resilience than the control. In addition, the patent of the U.S.A. No. 4,194,069 indicates that N, N'-bis (3-dimethylaminopropyl) urea (II) produces slight foam shrinkage and thick cells compared to N- (3-dimethylaminopropyl) -N '- (3-morpholinopropyl) urea. Thus, one would not be motivated to add (II) to reduce force-to-crush values. The advantage is that catalyst ratios can be used to systematically control fluidity, air flow and force-to-crush, and thereby providing more latitude for flexible foam processing. DECLARATION OF INDUSTRIAL APPLICATION The invention provides catalyst compositions for producing flexible polyurethane foam.

Claims (16)

1. CLAIMS 1. In a method for preparing a flexible polyurethane foam by reacting an organic polyisocyanate and a polyol in the presence of a blowing agent, a cell stabilizer and a catalyst composition, the improvement to control the processing latitude of the composition of foam comprising using a catalyst composition which essentially consists of > 0 a < 100% mol of 3-dimethylaminopropyl urea and > 0 a < 100% mol N, N'-bis (3-dimethylaminopropyl) urea. The method according to claim 1, wherein the catalyst composition comprises 50 to 95% mol of 3-dimethylaminopropyl urea and 5 to 50% mol of N, N'-bis (3-dimethylaminopropyl) urea. The method according to claim 1, for improving the flowability of the flexible polyurethane foam comprising using a catalyst composition comprising 80 to 95% mol of 3-dimethylaminopropyl urea and 5 to 20% mol of N, N'-bis (3-dimethylaminopropyl) urea. The method according to claim 1, for improving the air flow and decreasing the strength-to-crush of the flexible polystyrene foam, which comprises using a catalyst composition comprising 5 to 20 mol% of 3-dimethylaminopropyl urea and 80 to 95% by mol of N, N'-bis (3-dimethylaminopropyl) urea. 5. The method according to claim 1, wherein the catalyst composition is used in combination with other tertiary amine, organotin or urethane carboxylate catalysts. 6. The method of compliance with the claim 2, wherein the catalyst composition is used in combination with other tertiary amine, organotin or urethane carboxylate catalysts. 7. The method of compliance with the claim 3, wherein the catalyst composition is used in combination with other tertiary amine, organotin or urethane carboxylate catalysts. 8. The method of compliance with the claim 4, wherein the catalyst composition is used in combination with other tertiary amine, organotin or urethane carboxylate catalysts. 9. In a flexible polyurethane foam composition having a density of 16 to 48 kg / m3 (1 to 3 lb / ft3) comprising the following components in parts by weight (pbw = parts by weight): Polyol 20-100 Poliol Polymer 80-0 Silicone Surfactant 1 -2.5 Blowing Agent 2-4.5 Interleaver 0.5-2 Catalyst Composition 0.2-2 Isocyanate index 70-115 the improvement comprising > 0 a < 100% mol of 3-dimethylaminopropyl urea and > 0 a < 100% by mol of N, N'-bis (3-dimethylaminopropyl) urea. The flexible foam composition according to claim 9, wherein the catalyst composition comprises 50 to 95% mol of 3-dimethylaminopropyl urea and 5 to 50% mol of N, N'-bis (3-dimethylaminopropyl) urea. 11. The flexible foam composition according to claim 9, wherein the catalyst composition comprises 80 to 95% mol of 3-dimethylaminopropyl urea and 5 to 20% mol of N, N'-bis (3-dimethylaminopropyl) urea. The flexible foam composition according to claim 9, wherein the catalyst composition comprises 5 to 20% mol of 3-dimethylaminopropyl urea and 80 to 95% mol of N, N'-bis (3-dimethylaminopropyl) urea. 13. The flexible foam composition according to claim 9, wherein the catalyst composition is in combination with other tertiary amine, organotin or urethane carboxylate catalysts. 14. The flexible foam composition according to claim 10, wherein the catalyst composition is in combination with other tertiary amine, organotin or urethane carboxylate catalysts. 15. The flexible foam composition according to claim 11, wherein the catalyst composition is in combination with other tertiary amine, organotin or urethane carboxylate catalysts. 16. The flexible foam composition according to claim 12, wherein the catalyst composition is in combination with other tertiary amine, organotin or urethane carboxylate catalysts.