QUATERNARY AMMONIUM BORATES AS POLYURETHANE CATALYSTS

Abstract: A method of manufacturing a polyurethane foam that comprises blending an isocyanate with a polyol and a catalyst. The catalyst adds to the hydroxyl content of the blend and thereby permits a reduction in the amount of polyol required to produce a given amount of the foam.

Description: QUATERNARY AMMONIUM BORATES AS POLYURETHANE CATALYSTS BACKGROUND OF THE INVENTION This invention relates to the field of polyurethane chemistry. More specifically, the invention relates to a method of manufacturing a polyurethane foam using a catalyst as a co-polyol. Polyurethane foams may be rigid, semi-rigid, or flexible and have densities ranging from less than one pound to greater than fifty pounds"*per cubic foot. These foams have excellent strength, durability, light color, uniform cell size, and good heat-insulating properties and can be used in cushions, bedding, and fabric backing. The manufacture of polyurethane foams is well- known in the art, and different embodiments are disclosed in several U.S. Patents, including U.S. Patent Nos. 3,661,809; 3,726,816; and 4,256,802. Urethanes or polyurethanes can be formed by a reaction of di- or polyfunctional hydroxyl compounds, for example, hydroxyl-terminated polyesters or polyethers with di- or polyfunctional isocyanates. The repeating unit of a linear polyurethane derived from a dihydroxy compound, HOROH, and a diisocyanate, OCNR'NCO, can be represented by the general formula: 0 II (R - O - C - NH - R'.n In the specific method for the manufacture of polyurethane or a polyisocyanurate foam as set forth in U.S. Patent No. 4,256,802, issued to Koehler et al on March 17, 1981, two components are blended with one another, stirred, and then allowed to rise in an open container so as to form the desired foam. These components are known as the "A" and "B" components, with the "A" component comprising the isocyanate and the "B" component comprising a blend of polyol, catalyst, surfactant, and blowing agent. The isocyanates disclosed in the several above-listed patents may be selected from a broad group of compounds, including toluene- 2,4-diisocyanate, 2,4-dimethyl-1,3-phenylene iisocyanate, 2,6- diisocyanate-benzofuran, and 2,4,6-toluenetri- isocyanate. Typical polyols may include pentaerythitol, ethoxylated trimeth lolpropane, or diethanolamine. Suitable surfactants include silicone glycol copolymers, and the blowing agent is often trifluorochloro ethane or dichloro- methane. Catalysts are selected from a group including quaternary ammonium bases, alkali metal salts, and organic quaternary ammonium salts. However, the methods of polyurethane foam ' manuf cture disclosed in the above patents all require that both a conventional polyol and a conventional catalyst be used, and the catalyst does not act as a polyol in the reaction. SUMMARY OF THE INVENTION This invention comprises a novel method for the manufacture of a polyurethane foam, comprising blending the isocyanate with a polyol and a catalyst, the catalyst acting as a co-polyol in the reaction and being of the general formula: wherein x is an integer between 1 and 10, R4 is either -H, C 6 H 5® -CH2O-C6H5CH3, or an unsubstituted or halogen substituted C1-C4 alkyl group, and wherein Rj, R2, and R3 are selected from the group including -(CH2CHR4θ) x H, and aliphatic radicals having between 1 and 22 carbon atoms, and wherein Y^ is an anion. The term "aliphatic radical" means alkyl and alkenyl groups having from 1 to 22 carbon atoms inclusive. Representative of alkyl groups are methyl, propyl, pentyl, octyl, decyl, tridecyl, octadecyl, and isomeric forms (for the longer groups) thereof. Representative of alkenyl are pentenyl, heptenyl, nonenyl, dodecenyl, hexadecenyl, octadecenyl, and isomeric forms thereof. This invention is based on the discovery that the polyurethane foams may be manufactured with smaller amounts of the polyol than- is otherwise required by using a novel catalyst that has as a substituent one or more of the radicals selected from the group including propoxy, ethoxy, or styrene oxide. Further, the "B" component mix is a iscible blend having a relatively long shelf life. An object of the present invention is thus a method of manufacturing a polyurethane foam using a catalyst that is novel in that it initiates the reaction and also reduces the amount of polyol required for the formation of a given amount of foam. DESCRIPTIO OF THE PREFERRED EMBODIMENTS This invention concerns rigid polyurethane foams and particularly rigid polyurethane foams which are generally made by reacting. an isocyanate and a hydroxy- terminated or polyhydric compound, i.e., a polyol, in the presence of a surfactant, catalyst and blowing agent. "Rigid" polyurethane foams are in contrast to "flexible" foams and "semi-rigid" foams. A good measure of rigidity is not generally available or definable, but the differences between the foams of various rigidities are recognized in the art. The polyurethane foams in accordance with the present invention are prepared simply by mixing together, in proportions and ranges specified below, the "A" and "B" components. The "B" component comprises a polyhydric alcohol, or a hydroxy-ter inated or polyhydric compound, the catalyst, surfactant, and blowing agent, which is reacted with the "A" component comprising the isocyanate or -NCO containing compound. The polyol may thus be selected from a group including, for example: polyalkylene ether glycols, triols, and so forth having up to eight hydroxyl groups; branched-chain polyols of hydroxyl terminated condensation products of propylene oxide or of mixed ethylene and propylene oxides or other alkylene oxides with polyhydric alcohols of 2 to 8 hydroxyl groups such as ethylene glycol, glycerol, pentaerythritol, sorbitol, sucrose, and methyl glucoside; linear polyols such as dipropylene glycol, tripropylene glycol, or polypropylene ether glycol. The surfactant may be selected from the group including silicone glycol copolymers with direct silicone-carbon bonds such as surfactants DC-195 or DC-193, sold by the Dow Corning Corporation. Minor amounts of such conventional surfactants, including silicone oils and soaps and siloxaneoxyalkylene block copolymers, in quantities up to about 2 parts by weight of the surfactant per 100 parts of the polyol, are usef l in improving the cell structure of the polyurethane foam in that they stabilize the cell structure during foam rise and prevent slumping, collapsing, and ripping of the cells. The blowing agent, also known as the foaming agent, may include many of those known in the art, including fluorocarbons which can be used for blowing polymer mixtures into cellular polymers. Generally speaking, such blowing agents are low-boiling (less than 110°C) liquids which vaporize under the influence of the exothermal polymerization reaction and which are inert towards the isocyanate. Examples of such preferably used liquids are halogenated hydrocarbons such as ethylene chloride, trichlorofluoromethane, dichlorodifluoromethane, dichloromono- fluoromethane, dichlorotetrafluoroethane, ethyl chloride, methylene chloride, chloroform, carbon tetrachloride, and 1,1,2-trichloro-l,2,2-trifluoroethane. Mixtures of these low- boiling liquids and/or mixtures of these liquids with other substituted or unsubstituted hydrocarbons can also be used. The appropriate amount of low-boiling, liquid blowing agent for the manufacture of foamed polyurethane materials is a function of the desired foam density. Generally, quantities of 5 to 40 percent by weight relative to 100 parts by weight of isocyanate provide satisfactory results. ^ O PI Suitable catalysts include compounds having the formula: wherein x is an integer between 1 and 10, R4 is either -H, C5H5©, -CH2O-C6-H5CH3, or an unsubstituted or halogen substituted C1-C4 alkyl group, and wherein R]_, R2, and R3 are selected from the group including -(CH2CHR4θ) x H, and aliphatic radicals having between 1 and 22 carbon atoms, and wherein Y® is an anion. Suitable anions for example, may include the borate (H2BO3"-), phosphate (H2P04-), and acetate (CH3COO—) anions. Suitable catalysts therefore include the quaternary ammonium compounds: polyoxyethylene (5) cocoammonium borate, which may be obtained from the Ar ak Company (300 South acker Drive, Chicago, Illinois 60606) as Ethoquad® CD/15 Borate; tetraethanol ammonium borate, also known as Armak's Ethoquad® TEA/11 Borate; polyoxyethylene (4) ditallow- ammonium borate, also known as Armak's Ethoquad® 2T/14 Borate; polyoxyethylene (15) cocoammonium borate, available as Armak's Ethoquad® C/25 Borate; methylpolyoxyethylene (15) octadecyl-ammonium borate, available as Armak's Ethoquad® " 18/25 Borate; polyoxyethylene (4) cocoammonium borate, available as Armak's Ethoquad® CD/14 Borate; polyoxyethylene (4) cocoammonium phosphate, available as Armak's Ethoquad® CD/14 Phosphate; polyoxyethylene (4) tallow-ammonium borate, available as Armak's Ethoquad® T/14 Borate; and polyoxy¬ ethylene (4) dihydrogenatedtallowammonium borate, sold as Armak's Ethoquad® 2HT/14 Borate. The range of catalyst to polyol is between 1:250 and 70:30 by weight, with the preferred amount from about 11% to 66% and the most preferred being about 25% (1:4). The "A" component comprises the isocyanate (polyisocyanate) to be reacted with the "B" component. Examples of suitable isocyanates or reactive -NCO containing compounds which may be employed in practicing the invention include: 2,4-tolylene diisocyanate; diphenylmethane diisocyanate; butylene-l,4-diisocyanate; octamethylene diisocyanate; benzene triisocyanate; 4-bromo-l,3-phenylene- diisocyanate; 4-ethoxy-l,3-phenylene- diisocyanate; 2,4-diisocyanatostilbene; 2,5-fluorenediisocyanate; 2,6-diisocyanatobenzofuran; 2,4,6-toulenetriisocyanate; and other organic pol isocyanates conventionally and previously employed in the art for this purpose. In the examples listed hereinbelow, Mondur MR is the preferred organic polyisocyanate. Mondur MR is the trade name of Mobay Chemicals for a polycyclic aromatic polyisocyanate corresponding to the formula: wherein n varies from 1 to 10. Mondur MR is a polymeric polyaryl- polyisocyanate prepared by phosgenation of aniline and formaldehyde in a mineral acid. The polyisocyanate has 31.5-32% active -NCO groups and a viscosity of about 200 cps at 25°C. The general procedure is to weigh in a container, such as an unlined paper cup, the compounds of the "B" component. The "B" component will comprise one or more polyols, as for example Voranol® 490, Voranol being the tradename of Dow Chemical Company for polyether polyols; a surfactant, such as Silicone, DC-193, a silicone-glycol copolymer available from Dow Corning; a blowing agent, such as Freon R-ll-A, DuPont's tradename for its trifluorochloro- methane; and the catalyst/co-polyol. In this application, what is meant by a co-polyol is a compound contributing to the hydroxy content of the "B" component. The compounds comprising the "B" component are then blended together using, for example, a high speed air-driven mixer equipped with a stirrer blade. Some of the blowing agent may be lost by evaporation during blending; the mixer is stopped, additional blowing agent is added until the amount of blowing agent in the blend is back to the desired amount, and the mixer is restarted. EXAMPLES 1-3 These examples set forth three foams (A, B, and C) manufactured in accordance with the present invention. The polyurethane foams were prepared using three different catalyst/co-polyols, namely, either Ethoquad® CD/15 Borate, Ethoquad® 2T/14 Borate, or Ethoquad® TEA/11 Borate. The formulations and rise characteristics are set forth in Table 1. The "NCO/OH ratio" is indicative of the number of equivalents of the isocyanate used per equivalent of polyol. The ratio is determined by using the formula: hydroxyl equiv. of isocyanate x weight of isocyanate used NCO/OH ratio = hydroxyl number of polyol x weight of polyol used When the NCO/OH ratio is 1.05, there is a 5% excess of isocyanate over that stoichiometrically required for the given amount of polyol. The "cream time" is also known as the "initiation time", and is the interval between the blending of the "A" and "B" components and the turning of that mixture to a creamy color or to its commencing to rise or expand. The "gel time" is also known as the "string time", and is the interval between the blending of the "A" and "B" components and the point at which it is possible to draw a five to ten inch-long string or whisker when the surface of the foam is touched with a wooden spatula. The "rise time" is the interval between the blending of the "A" and "B" components and the time at which the foam stops rising in an open container. As the last few percent of this rise may be time-consuming and difficult to discern, a "95% rise time" is sometimes quoted. "Tack-free time" is the interval between the blending of the "A" and "B" components and the time a wooden spatula touched to the foam surface no longer sticks to it. TABLE 1 FOAMS B Ingredients : Component A: Mondur MR (hydroxyl 121.6 g 121.6 g 201.5 g equivalent=135 ) Component B: -Voranol 490 (hydroxyl 100 100 100 equivalent 3 =490) Voranol 575 (hydroxyl — — 120 equivalent 3 =604) DC-193 2.0 2.0 2.7 Freon 11-A 40.0 40.0 54.0 Ethoquad® CD/15 Borate 1.1 — — Ethoquad® 2T/14 Borate — 1.0 — Ethoquad® TEA/11 Borate — — 1.3 NCO/OH ratio 1.05 1.05 1.0 Characteristics: Cream time, sec 44 42 32 Gel time, sec 109 02 77 Rise time, sec 154 156 108 Tack-free time, sec 309 446 96 Examples 4-5 Foams D and E were prepared in the same general manner set forth hereinabove and using instead Voranol 575 for all the foams. The results are set forth in Table 2 below: TABLE 2 FOAMS D Ingredients: Component A: Mondur MR (hydroxyl 154 g 154 g equivalent=135) Component B: Voranol 575 (hydroxyl 100 100 number=604) DC-193 2.0 2.0 Freon 11-A 40.0 40.0 Ethoquad® 5D/14 Borate 1.0 — Ethoquad® 2T/14 Borate — 1.0 NCO/OH ratio 1.05 1.05 Characteristics: Cream time, sec 40 43 Gel time, sec 79 92 Rise time, sec 118 147 Tack-free time, sec 136 160 Exampl * ss 6-8 These foams (F-H) were prepared in accordance with the general procedures set forth hereinabove, using Ethoquad® CD/15 Borate as the catalyst/co-polyol. TABLE 3 FOAMS H Ingredients: Component A: Mondur MR (hydroxyl 201.5 g 201.5 g 200.1 g equivalent=135 ) Component B: Voranol 575 (hydroxyl 119.7 106.4 79.8 number=604) DC-193 2.7 2.7 2.7 Freon 11-A 53.2 53.2 53.2 Ethoquad® CD/15 Borate 13.3 26.4 53.2 (hydroxyl number=600) NCO/OH ratio 1.05 1.05 1.05 Characteristics: Cream time, sec 46 25 6 Gel time, sec 79 38 * Rise time, sec 103 44 * Tack-free time, sec 119 48 * *too fast to measure In these examples, the hydroxyl content is maintained by using a fixed weight of polyol and catalyst. Here, the sum of the mass of polyol and catalyst was a constant 132.9 +/- 0.1 g. As more of the novel catalyst was added, the tack-free time dropped significantly. Examples 9-10 These foams (I-J) were prepared in accordance with the general procedures set forth hereinabove, using Ethoquad® CD/14 Borate and Ethoquad® CD/14 Phosphate as the catalyst/co-polyol. TABLE 4 FOAMS Ingredients: Component A: Mondur MR (hydroxyl 201.5 g 201.5 g equivalent=135) Component B: Voranol 575 (hydroxyl 133 133 number=604) DC-193 2.7 2.7 Freon 11-A 53.2 53.2 Ethoquad® CD/14 Borate 1.3 — Ethoquad® CD/14 Phosphate — 1.3 NCO/OH ratio 1.05 1.05 Characteristics: Cream time, sec 39 51 Gel time, sec 70 86 Rise time, sec 99 113 Tack-free time, sec 104 130 Examplesi 11-16 These foams (K-P) were prepared in accordance with the general procedures listed hereinabove, using Ethoquad® T/14 Borate and Ethoquad® 2HT/14 Borate as the catalyst/co-polyol. TABLE 5 FOAMS K M N 0 Ingredients: Component A: Mondur MR (hydroxyl 201.5 g 201.5 g 201.5 g 201.5 g 201.5 g 201.5 g equivalent=135) Component B: Voranol 575 (hydroxyl 133 119.7 106.4 133 119.7 106 number=604) DC-193 2.7 2.7 2.7 2.7 2.7 2.7 Freon 11-A 53.2 53.2 53.2 53.2 53.2 53.2 Ethoquad® T/14 Borate 1.3 13.3 26.6 — — — Ethoquad® 2HT/14 Borate — — — 1.3 13.3 26.6 NCO/OH ratio 1.05 1.05 1.05 1.05 1.05 1.05 Characteristics: Cream time, sec 54 28 16 62 26 6 Gel time, sec 87 43 23 98 40 * Rise time, sec 17 50 27 152 47 * Tack-free time, sec 30 55 30 179 51 * *too fast to measure ■ A Examples 17-18 Two foams (Q and R) were manufactured in accordance with the general procedures set forth herein- above, except that foam Q used a conventional catalyst instead of the present catalyst. Foam R used a reduced amount of the polyol Voranol 575; the reduction was on a one-for-one basis, i.e., for each gram of Ethoquad® T/14 Borate used in Foam R, one gram less of Voranol 575 (as compared with Foam Q) was used. A one-for-one reduction of Voranol 575 was made because the hydroxyl number of Ethoquad® T/14 Borate (600) is virtually identical to that of Voranol 575 (604); hence, a one-for-one substitution retains constant both the hydroxyl content of the blend and the NCO/OH ratio. TABLE 6 FOAMS Q R Ingredients : Component A: Mondur MR ( hydroxyl 201.5 g 201.5 g equivalent=135 ) Component B : Voranol 575 (hydroxyl 133 119 .7 number=604 ) Polycat 8* 1.3 Ethoquad® T/14 Borate — 13.3 DC-193 2. 7 2. 7 Freon 11 -A 54 54 Characteristics : Cream time , sec 33 19 Rise time , sec 85 39 Foam we ight , grams 334 338 *Polycat 8 is a di e thylcyclohexylamine . " Polycat" is a tradename of Abbott Laboratories . As indicated above, the mass of foam formed remains approximately constant when a conventional, prior art catalyst is replaced by the present catalyst and the amount of polyol reduced by the amount of the present catalyst/co-polyol added. The present catalyst therefore replaces a conventional catalyst and reduces the amount of polyol required with no loss in foam production.

Claims: WHAT IS CLAIMED IS: 1. A method of manufacturing a rigid polyurethane foam, comprising blending an isocyanate with a polyol and a catalyst, said catalyst being a co-polyol in said method and being of the general formula: wherein x is an integer between 1 and 10, R4 is either -H, CgH^- 3 , -CH2O-C5H5CH3, or an unsubstituted or halogen substituted C1-C4 alkyl group, and wherein R * ]_, R2, and R3 are selected from the group including -(CH2CHR4θ) x H, and aliphatic radicals having between 1 and 22 carbon atoms, and wherein Y- 5- is an anion. 2. The method as set forth in claim 1, comprising blending with said isocyanate, polyol, and catalyst, a surfactant and a fluorocarbon blowing agent. 3. The method as set forth in claim ' 1, wherein said isocyanate comprises a mixture of polyaryl isocyanates containing methylene diphenyl diisocyante and higher functional isocyanates. 4. The method as set forth in claim 1, wherein ^ is the H2B03 <S ' anion. 5. The method as set forth in claim 1, wherein Y 3 is the H2PO4' 3 anion. 6. The method as set forth in claim 1, wherein H is the acetate anion. 7. A process for the preparation of a cellular, rigid polyurethane, said process comprising blending an "A" component comprising an organic isocyanate in the presence of a "B" component comprising a polyol, a fluorocarbon blowing agent, and a quaternary ammonium catalyst, said catalyst acting as a co-polyol and including either a propoxyl, ethoxyl, or styrene oxide group in the cationic portion thereof. 8. The process as set forth in claim 7, wherein said sufactant is present in quantities up to 2 parts by weight per 100 parts of said polyol. 9. The process as set forth in claim 7, wherein said fluorocarbon blowing agent is present in quantities of from 5 to 40 parts by weight per 100 parts of said organic isocyanate. 10. The process as set forth in claim 7, wherein said catalyst is present in quantities of from about 1 part by weight to 250 parts polyol and 70 parts catalyst to 30 parts polyol. 11. A method of manufacturing a polyurethane foam, comprising blending an isocyanate with a polyol, a fluorocarbon blowing agent, a catalyst, and a surfactant, said catalyst being a co- polyol in said method and being of the general formula: wherein x is an integer between 1 and 10, R4 is either -H, C 6 H 5 Θ ' -CH2O-C6H5CH3, or an unsubstituted or halogen substituted C1-C4 alkyl group, and whereάn Ri, R2, and R3 are selected from the group including -(CH2CHR4θ) x H, and aliphatic radicals having between 1 and 22 carbon atoms, and wherein Y *3 is an anion, said surfactant being present in quantities up to 2 parts by weight per 100 parts of said polyol, said blowing agent being present in quantities from 5 to 40 parts by weight per 100 'parts of said organic isocyanate, and said catalyst being present in quantities of from 1 to 30 parts by weight per 100 parts polyol. 12. The method as set forth in claim 11, wherein said catalyst is polyoxyethylene (5) cocoammonium borate. 13. The method as set forth in claim 12, wherein said blowing agent is trifluorochloromethane. 14. The method as set forth in claim 11, wherein said catalyst is polyoxyethylene (4) tallowammonium borate, 15. The method as set forth in claim 14, wherein said blowing agent is trifluorochloromethane.

Inventors: RICHMOND JAMES MATTHEW, WHITE KENNETH B, RICHMOND, JAMES, MATTHEW, WHITE, KENNETH, B.
Applicants: AKZONA INC, AKZONA INCORPORATED
Application year: 1983
Main classification: C08G18
IPC codes: C08F8, C08G18