Stabilized hydrochlorofluorocarbon blowing agents

Abstract: HCFC blowing agents such as 141b which are stabilized with alpha-pinene oxide, limonene dioxide, or 1,2-hexadecene oxide.

Description: This invention relates to a foam premix formulation comprising a polyol, 1,1-dichloro-1-fluoroethane, and an inhibitor which consists essentially of alpha-pinene oxide, limonene dioxide, or 1,2-hexadecene oxide in an amount effective to stabilize the 1,1-dichloro-1-fluoroethane against decomposition into 1-chloro-1-fluoroethylene. Polyurethane and polyisocyanurate foams are conventionally prepared by reacting an organic polyisocyanate (including diisocyanate) "A-side" component with a "B-side" polyol premix component containing organic polyol, blowing agent, surfactant, catalyst, and possibly other additives such as flame retardants, antioxidants, and U.V. stabilizers. These A-side and B-side components may be purchased by the end-user in separate containers and stored for later use. Since decomposition of the HCFC blowing agents has been observed in the B-side premixes during storage and during the process of making the foam, HCFC compositions inhibited against such decompositions would be highly desirable. 141b blowing agent has been observed to decompose during the foam-making process to up to about 1%, depending on the formulation and reaction conditions, of various decomposition products of which by far the predominant product is 1-chloro-1-fluoroethylene ("1131a"). Inhibition of such decomposition is desired both because of toxicity concerns and because the decomposition is accompanied by the formation of equivalent amounts of acid which in turn causes catalyst deactivation. According to the present invention a foam premix formulation is provided comprising a polyol, 1,1-dichloro-1-fluoroethane, and an inhibitor which consists essentially of alpha-pinene oxide, limonene dioxide, or 1,2-hexadecene oxide in an amount effective to stabilize the 1,1-dichloro-1-fluoroethane against decomposition into 1-chloro-1-fluoroethylene. The foam premix formulation may also optionally contain other ingredients such as surfactants, catalysts and flame retardants. It has now been found that 141b is stabilized against decomposition by the addition of alpha-pinene oxide, limonene dioxide, or 1,2-hexadecene oxide as an inhibitor (boiling points, in degrees C, of 177, 242, and 315, respectively). Low boiling epoxides, such as 1,2-epoxybutane, have been found to be ineffective. The inhibitor is present in an effective amount, typically from about 0.01 to about 2% by weight, based on the weight of the blowing agent(s), preferably 0.05 to 1%. The foam premix formulations include a polyol or a fully formulated B-side formulation containing a polyol, and, optionally a catalyst, a surfactant and other additives. Typical polyols are, for example, Stepanol PS 2502A, an aromatic polyester polyol sold by the Stepan Company; Terate 203, an aromatic polyester polyol sold by Hercules, Inc.; Pluracol Polyol 975, a sucrose-based polyol sold by BASF; Poly-G 71-530, a polyether polyol sold by Olin; and Quadrol, an amine-based polyol supplied by BASF. Typical catalysts include Potassium HEX-CEM, a potassium octoate sold by Mooney Chemicals; Polycat 41, an N,N,N-tri(dimethylaminopropyl)cyclohexatriazine catalyst sold by Air Products; Polycat 8, an N,N-dimethylcyclohexylamine catalyst sold by Air Products; Dabco TMR-30, a 2,4,6-tri(dimethylaminomethyl)phenol supplied by Air Products; and Dabco K-15, a potassium 2-ethylhexoate in diethylene glycol supplied by Air Products. A typical surfactant is Dow Corning 193, a silicone polymer surfactant. A typical A-side component is Mondur E-489, an aromatic diisocyanate supplied by Mobay Chemical Co., or Lupranate M20S, a polymethylene-diisocyanate supplied by BASF. The invention was illustrated by first preparing a polyurethane foam with 141b in the absence of inhibitor by stirring a formulation containing polyol (100g of Stepanol PS 2502A), 141b (25.8g), surfactant (1.51g of Dow Corning 193), catalyst (2.82g of Potassium HEX-CEM and 0.7g of Polycat 41), and diisocyanate (127.2g of Mondur E-489). The contents were poured into a box and the resulting foam was left to cool to room temperature. After curing the foam at 121°C (250°F) for 20 hours, the cell gas was analyzed by crushing a sample and injecting the released gas mixture directly to a gas chromatograph. The gas was found to contain 2180 ppm of 1131a, whereas the 141b starting material contained only 10 ppm of 1131a. Other minor components in the cell gas totalled only about 440 ppm, similar to the levels found in the 141b starting material. When 0.6 weight % of each of 1,2-hexadecene oxide and alpha-pinene oxide were dissolved in 141b, foams prepared as aforesaid contained only 1193 ppm and 510 ppm of 1131a, respectively. The foregoing test was repeated using uninhibited 141b, 141b inhibited with 0.6 weight % of 1,2-hexadecene oxide, and 141b inhibited with 0.6 weight % of limonene dioxide. The prepared foams were found to contain 2590 ppm, 920 ppm, and 470 ppm of 1131a, respectively. In another illustration, polyisocyanurate premixes containing 141b (uninhibited and inhibited with 0.6 weight % alpha-pinene oxide) were aged at 54°C (130 degrees F). The premixes contained a polyol (100g of Stepanol PS-2502A), 141b (37g), surfactant (3g of Dow Corning 193), and catalyst (2.8g of Dabco K-15 and 0.9g of Dabco TMR-30). The uninhibited premix was found to contain 100 ppm of 1131a, while the premix containing alpha-pinene oxide contained only 10 ppm of 1131a.

Claims: A foam premix formulation comprising a polyol, 1,1-dichloro-1-fluoroethane, and an inhibitor which consists essentially of alpha-pinene oxide, limonene dioxide, or 1,2-hexadecene oxide in an amount effective to stabilize the 1,1-dichloro-1-fluoroethane against decomposition into 1-chloro-1-fluoroethylene. A foam premix formulation as in Claim 1 wherein the inhibitor is alpha-pinene oxide. A foam premix formulation as in Claim 1 wherein the inhibitor is limonene dioxide. A foam premix formulation as in Claim 1 further comprising a polyisocyanate.

Inventors: ELSHEIKH MAHER YOUSEF, MCMASTER CROOKER RICHARD, MURPHY JOHN ALAN, ELSHEIKH, MAHER YOUSEF, MCMASTER CROOKER, RICHARD, MURPHY, JOHN ALAN
Applicants: ATOCHEM NORTH AMERICA ELF, ELF ATOCHEM NORTH AMERICA, INC.
Application year: 1992
Main classification: C08J9
IPC codes: C08J9