EXTENSION OF RIGID URETHANE FOAMS USING ALKOXYLATED WOOD DERIVATIVES W I L L I A M C . D A R R A N D J O H N K. B A C K U S Mobay Chemical Go., Pittsburgh, Pa. 15205
The importance of rigid urethane foams of lower cost but high performance in many applications has led to extensive investigations of low cost polymer extenders which do not adversely affect foam properties. Systems based on crude tall oil, castor oil, and certain wood-based by-products have been reported, but the less than satisfactory physical properties o f such foams have retarded the general acceptance of extender techniques. Recent work has shown alkoxy derivatives of products from the processing of aged pine stumps t o b e particularly valuable in the preparation of rigid urethane foams. Treatment of the parent natural products b y ethylene or propylene oxide has yielded materials more easily handled and, therefore, capable of use at higher concentrations, as much as 3070 in some foam formulations. Such highly extended formulations, processed by standard machines and techniques, have resulted in rigid foams having excellent properties. In addition, the aromatic nature of the wood-derived products has allowed preparation of flame-retardant foams using a minimum concentration of reactive or nonreactive flame retardants without serious loss of other physical properties. Foams containing these extenders are equal to and, in some areas, superior to conventional polyether based rigid urethane products.
HE use of rigid urethane foam in such large-volume appliTcations as construction, thermal insulation, and transportation is increasing rapidly (Siren, 1965), primarily because of concurrent reductions in raw material costs and improvements in both physical properties and application techniques. T h e search for low cost raw materials has includeda variety of natural products. Castor oil, both with and without modification, has long been used as a component of urethane polymers (Saunders and Frisch, 1962). lMore recently, tall oil and its derivatives have been suggested as components of rigid urethane foams (Gemeinhardt et al., 1962; Hudson, 1963) and propylene oxide adducts of starch derivatives, a-methyl glucoside, sorbitol, and sucrose have become commonly used raw materials. Among the most promising recently reported rigid urethane foam extenders is a series of resins obtained from destructive distillation and solvent extraction or pine wood (Coglianese, 1965; Coglianese and McCorkle, 1962). These resins are complex thermoplastic materials having active hydrogen atoms in the form of methylol, phenolic hydroxyl, and carboxyl groups as well as reactive unsaturation. Good foam properties have been reported for formulations in which the pine resins were dissolved in foam raw materials of lower viscosity. Because of the high viscosity of such solutions, however, the concentration of pine resin in foam formulations has been limited practically to approximately 40% by weight of the resin component. More recently, one manufacturer of high melting pine wood resin has made its ethylene oxide and propylene oxide derivatives available in development quantities (Hercules, 1965; Rummelsburg, 1951). Rigid foams containing the alkoxylated resins have been shown to be distinctly superior to the unmodified extenders. Processing qualities of the extended urethane formulations were improved and the rates of reaction between isocyanate and resin made more uniform by conversion of the carboxyl and phenolic hydroxyl groups, in particular, to primary or secondary aliphatic hydroxyl
groups. In addition, resin mixtures containing as much as 60% of the ethylene or propylene oxide adducts were converted to foam without trouble by conventional machinery. Properties of the rigid foams prepared from such highly extended formulations were comparable to those of foams containing no pine wood resin and raw material costs were reduced as much as 20y0. T h e extended foams were easily made self-extinguishing by addition of common flame-retardant additives. Similar experiments were conducted using a liquid pine wood resin (Cabot Corp., 1965). As expected, the lower viscosity of the liquid resin simplified the processing of highly extended formulations. T h e concentration of liquid resin extender was limited, however, to approximately 3ooj, by weight of the resin component by poor high temperature dimensional stability caused by the less reactive, less aromatic resin. Experimental
Rigid urethane foams were prepared from raw materials typical of those currently used commercially. Tables I and I1
Table 1.
Polyols Used in Preparing Extended Rigid Urethane Foams Hydroxyl Propylene Oxide Adduct Nucleus No.
Aliphatic tetrol (560)a Pentaerythritol Aliphatic tetrol (460)b Pentaerythritol Heterocyclic tetrol (440)c Methyl glucoside Heterocyclic octo1 (410)d Sucrose N,N,N',N'-TetrakisEthylenediamine (2-hydroxyprppy1)ethy lenediamines a P e p 450, Wyandotte Chemical Corp. b P e p 550, Wyandotte Chemical Carp. c E-201, Wyandotte Chemical Carp. d RS-410, Daw Chemical Co. e Quadrol, Wyandotte Chemical Cor).
VOL. 6
560 460 440 41 0
768
NO. 3 S E P T E M B E R 1 9 6 7
167
Table II.
Isocyanates Used in Preparing Extended Rigid Urethane Foams Amine Polyisocyanate Type Equivalent
Polymeric isocyanate (132p MDI Polymeric isocyanate (115)* Aromatic Distilled grade, 80% 2,4-/20 yo TDI 2,6-tolylene diisocyanatec Mondur M R , Mobay Chemical Co. Mondur M T - 4 0 , hlobay Chemical Go. c Mondur TD-80, Mobay Chemical Co.
132 115
87
Q
summarize important properties of the polyols and polyisocyanates, respectively. T h e selection covers the major structural types of common polyoxypropylene ether polyols and both diphenylmethane (MDI) and tolylene (TDI) type isocyanates. T h e three flame retardants of Table I11 represent liquid reactive, liquid nonreactive, and solid nonreactive types. T h e flame-retardant poly01 was believed to be a combination of organophosphorus and polyoxypropylene ether structures containing terminal hydroxyl groups which allowed the flame retardant to become a n integral part of the urethane polymer. T h e nonreactive liquid flame retardant contained high concentrations of both phosphorus and chloride. The third product, a water-insoluble inorganic phosphate, contained a very high concentration of phosphorus and was used as a finely divided power. Properties of the pine wood resins evaluated as rigid urethane foam extenders are given in Table IV. Two of the extenders, pine wood resins A and B, were similar products supplied by different manufacturers. Both were complex, high melting mixtures obtained as the hydrocarbon-insoluble fraction of the
Table 111.
Flame Retardants Used in Preparing Extended Rigid Urethane Foams
Wt. Flame Retardant % P Flame-retardant polyola 5 . 6 Nonreactive flame 15 retardant6 Solid flame retardantc 30
wt. yo
... 27
Physical State Liquid Liquid
Hydroxyl NO.
450 Nonreact.
., .
Powdered Nonreact. solid a Experimental Polyol E-204S, Wyandotte Chemical Corp. b Phosgard C-22-R, Monsanto Co. c Phoschck P / 3 0 , Monsanto Co.
Table IV.
Extender Acid No. Hydroxyl No.
Results and Discussion
O u r original intent of lowering the costs of rigid urethane foams without sacrificing physical properties seems to have
Pine Wood Resins and Alkoxylated Derivatives Evaluated as Rigid Urethane Foam Extenders Adducts of Resin A Thermoplastic Resin Aa Resin B* Liquid Resinc EOd PO6 94 94 56 0.1 4,000,000
...
370
>4,000,000
...
410
2,600 370,000 6,200
... ...
456 332 374
~
VOL. 6
...
~~~~
NO. 3
SEPTEMBER
1967
171
through a gear pump. This technique would need modification if the mixture were allowed to stand long enough for settling to take place. The data in Table V I 1 were obtained from foams composed of EO wood resin extender, phosphorus-containing (reactive) polyol, and polymeric isocyanate (132). The purpose of these experiments was to determine if flame-resistant foams couid be produced using a resin composed of only phosphoruscontaining poly01 in conjunction with high concentration of extenders. This was worthwhile, since these polyols were priced the same as normal polyethers; therefore, the final result would be a flame-resistant foam without extra cost. These foams were acceptable except for borderline dimensional stability. This problem was solved by using slightly more crosslinking in the polymer structure. Several low equivalent weight polyhydroxy compounds performed acceptably in this application. The flame resistance of all these foams was good. Several unmodified wood resins were used as extenders in the basic foam systems described earlier. The d a t a in Table V I 1 1 show that these products were acceptable and performed rather well at lower (30 to 40%) concentrations in the poly01 blends. The maximum level of loading was controlled by high viscosity limitations in the case of the solid wood resins and the plasticizer characteristics of the liquid resin extender. The foams produced containing the solid extender were good, with the exception of some unwanted friability. T h e liquid wood resins when used at higher (>30%) concentrations caused dimensional stability problems in otherwise acceptable foams. T h e liquid product could, however, be used with different high viscosity heterocyclic-type polyether polyols, whereas the solid resins could be blended with only a few low viscosity materials. T h e carboxylic acid contained in all of the nonalkoxylated wood resins caused long-term storage problems if the systems
were preformulated for later use as two-component systems. The alkoxylation of the acid groups reduced this problem considerably. T h e data in Table IX point out the processing characteristics that were found for the many different poly01 blends listed herein. The viscosity data show clearly the great variations seen with different poly01 blends and explain the limitations mentioned above. Acknowledgment
The authors appreciate the help of D. F. Morgan and J. R. Carazola in the experimental portion of this project and the advice of J. H. Saunders and P. G. Gemeinhardt during the planning and reporting of the work. The contribution of the Mobay physical testing group is also gratefully acknowledged. literature Cited
Cabot Corp., unpublished data, 1965. Coglianese, F. A., J. Cellular Plastics 1, 42 (1965). Coglianese, F. A,, McCorkle, J. E., Belg. Patent 616,352 (Oct. 12, 1962). Gemeinhardt, P. G., Darr, W. C., Saunders, J. H., IND. ENC. CHEM.PROD.RES.DEVELOP. 1, 92 (1962). Hercules, Inc., unpublished data, 1965. Hudson, G. A,, U S . Patent 3,095,386(June 25, 1963). Rummelsburg, A. L.,U.S. Patent 2,555,901 (June 5, 1951). Saunders, J. H.,Frisch, K. C., “Polyurethanes, Chemishy and Technology,” Part I, pp. 6, 9, 48-54, Interscience, New York, 1962. Siren, R. L., Engineering Summer Conference on Cellular Plastics, Wayne State University, May 1965.
RECEIVED for review January 9, 1967 ACCEPTEDJuly 12, 1967
Division of Organic Coatings and Plastic Chemistry, 151st Meeting, ACS, Pittsburgh, Pa., March 1966.
INFLUENCE OF REACTION PARAMETERS ON DISPROPORTIONATION OF TETRALIN CATALYZED BY HYDROGEN FLUORIDE-BORON TRIFLUORIDE R0NA LD D
,
B U S H I C K , Research and Development Diuision, Sun Oil Go., Marcus Hook,Pa.
The HF-BFs-catalyzed disproportionation of Tetralin was investigated and found to b e extremely sensitive to changes in temperature, contact time, and catalyst concentration. At low temperature 6-(4-phenylbutyl)1,2,3,4-tetrahydronaphthaIenewas formed almost exclusively, whereas at higher temperature the reaction product consisted of benzene and an equilibrium mixture of 1,2,3,4,5,6,7,8-0ctahydroanthracene and 1,2,3,4,5,6,7,8-0ctahydrophenanthrene. Most of the data were obtained with a 10-fold excess of hydrofluoric acid. Cocatalysts other than BFs were also investigated.
u
the disproportionation of alkyl-substituted aromatics to higher and lower homologs (Brown and Smoot, 1956; Lien and McCaulay, 1 9 5 3 ; Nightingale, 1939), the acid-catalyzed disproportionation of alicyclic systems such as Tetralin has received little attention. Schroeter (1924), some 43 years ago, was the first to investigate the action of aluminum chloride on 1,2,3,4-tetrahydronaphthalene (Tetralin). The major NLIKE
172
I&EC PRODUCT RESEARCH A N D DEVELOPMENT
products isolated were benzene, 1,2,3,4,5,6,7,8-octahydroanthracene (OHA, I), 1,2,3,4,5,6,7,8-0ctahydrophenanthrene (OHP, 11), and 6-(4-phenylbutyl)-l,2,3,4-tetrahydronaphthalene (PBT, 111) along with some 6-(1,2,3,4-tetrahydro-2naphthyl)-l,2,3,4-tetrahydronaphthalene and other substances. Both the conversion and yield were low. Barbot (1930) prepared PBT by the self-condensation of Tetralin in the pres-
