Comparison of our results with those of Schenck (1953) showed that the two processes gave substantially identical products in similar yields. This also was true when 6-pinene was oxidized. Elimination of the solvent in the oxidation step in the new process not only reduced the size of the reaction vessels and avoided the need for recovering 20-40 lb of solvent for each pound of product but also increased the rate of oxidation. K i t h two 280-W lamps, dilute solution runs (Schenck, 1953) required 60 hr (16,800 15' hr) t o get 0.5 mol of 02 absorption, compared t o 3 h r with one 500-W lamp (1500 W-hr) in run 4. Since Coxon, et al. (1970), stressed the fact that their method could be applied to New Zealand turpentine, we investigated whether pinocarveol could be produced by applying the photosensitized oxidation t o American turpentine. No difficulty was experienced. But, in contrast t o the selenium dioxide oxidation, the photosensitized oxidation was nonselective. Because the myrtenol, formed from P-pinene, could be separated from the pinocarveol with a simple fractionating column, both products were obtained in good purity and reasonable yield. Similar oxidation of 6-pinene gave a good yield of myrtenol. Usually the wholesale prices of turpentine and a-pinene are such that there would be no economic advantage to using turpentine; but for small laboratory-scale preparation, it is easier and cheaper to use gum turpentine than to order a-
pinene. Even from turpentine the yield (based on pinene consumed) of pinocarveol was better by neat photosensitized oxidation than by selenium dioxide-hydrogen peroxide oxidation, but the conversion per pass was lower. Coxon's method offers the more direct route to d-transpinocarveol of 90+% optical purity because @-pinene of this optical purity is readily available but I-a-pinene of this purity must be prepared by isomerization of p-pinene. However, his method cannot be used to get 1- or dl-pinocarveol because only 2-6-pinene is available. V i t h a-pinene as the raw material, d-, d-, and 1-trans-pinocarveol can all be prepared. X o s t commercial d-a-pinene is less than 50% optically pure, but several foreign turpentines contain d-a-pinene of 90% optical purity. literature Cited
Coxon, J. M., Dansted, E., Hartshorn, M. P., J . Chem. Eng. Data, 15, 336 (1970).
Kenney, R. L., Fisher, G. S., J . Amer. Chem. SOC.,81, 4288 (1959).
Kenney, R.L., Fisher, G. S., J . Org. Chem., 28, 3509 (1963). Kenney, R. L., Singleton, T. C., Fisher, G. S.,Anal. Cheni., 31, 1676 (1959).
Schenck, G. O., Eggert, H., Denk, W., Juslus Lzebigs Ann. Chem., 584, 177 (1953).
Wheeler, D. H., Oil Soup (Chicago),9 , 8 9 (1932). RECEIVED for review June 4, 1973 ACCEPTED July 18, 1973
Flammability Characteristics of Rosin Polyol Derived Rigid Polyurethane Foams Glen W. Hedrick" and Acy J. Green Naval Slmes Laboratory, Southern Region-Floridaldntilles
ilrea, Olustee, Fla. St072
Rigid polyurethane foams made from ethoxylated hydroxymethylated resin acids, obtained from the reaction of rosin and formaldehyde, were found to be slightly less flammable than foams derived from some conventional type glycols used by industry. Other evidence to substantiate this conclusion was that less fire retardant-about half as much-was required to reduce flammability of rosin polyol derived foams than required for foams made from the conventional glycols investigated. Polyol blends prepared from rosin-derived glycols containing 65-70y0 of resinyl material, more than previously reported, were fluid and readily mixed with isocyanates for preparation of foams.
P r i o r work has shown that rosin-derived polyols have utility in rigid polyurethane foams (Hedrick, 1973). Darr and Backus (1967) reported that an ethoxylated wood resin (Hercules ethoxylated Vinsol, EOV) gave self-extinguishing (SE) foams using a minimum of added fire retardant. EOV contains a high proportion of hydroxylated polynuclear compounds and resin acid derivatives and is similar in some respects to ethoxylated rosin-derived polyols. Accordingly, it was of interest to determine if the resinyl glycols affected the burning rates of foams containing the rosin derivatives. Ethoxylated
* To whom correspondence should be addressed 2921 Inglewood Avenue, Lake City, Fla. 32055.
acids obtained from the reaction of rosin and formaldehyde, rosin polyol A, and ethoxylated acids obtained from the methanol extract of the formaldehyde-modified rosin, rosin polyol B, were used as part of the glycol mixtures. In this paper, these resinyl mixtures have been called rosin polyols and rosin-derived glycols. Burning rates of foams containing these ethoxylated rosin derivatives were compared with foams made from a mixture of glycols consisting of DOWVoranol RS 450 and Wyandotte Pluracol PeP 450. Burning properties were determined by ASTM D1692-67T tests. Many compounds containing bromine or phosphorus or both are available for use as fire retardants for polyurethane Ind. Eng. Cham. Prod. Rer. Develop., Vol. 12,
No. 4, 1973
319
Table 1. Foam Formulations Materials for 1 equiv of polyol blend
B
A
RS 450, g TP 440, g PeP 450, g Fyrol6, g, %
C
D
E
62.71
G
F
I
H
64.22
K
J
1
65.93
65.00
64.00
30.42 23.10, 7.5
37.34 42.96 47.0 31.31 37.73 44.30 49.10 15.42, 9.17, 4.58, 25.06, 17.76, 10.45, 5.17, 5.04 3.01 1.51 7.13 5.09 3.02 1.5 103.90 102.3 101.06 100.02
40.70, 13.4 0.32, 0.10 0.50, 0.16 1.59, 0.52
40.34, 13.2 0.31, 0.10 0.49, 0.16 1.57, 0.50
40.30, 40.30, 42.90, 42.24, 41.73, 41.30, 13.25 13.28 12.20 12.12 12.06 12.01 0.31, 0.31, 0.22, 0.22, 0.22, 0.21, 0.10 0.10 0.06 0.06 0.06 0.06 0.49, 0.49, 0.56, 0.55, 0.54, 0.54, 0.16 0.16 0.16 0.16 0.16 0.16 1.55, 1.55, 2.51, 2.50, 2.47, 2.44, 0.51 0.51 0.72 0.72 0.71 0.71
307.7
305.7
304.2
55.52 51.47
53.47
50.00
129.45 99.30 Rosin polyol A, g Rosin polyol B, g 93.53 Blowing agent, 47.53, 45.90, 41.54, 40.54, 15.40 12.10 12.10 12.14 g, % 0.23, 0.21, 0.39, Tin compd, g, % 0.30, 0 10 0.06 0.06 0.12 Dabco R-8020, g, 0.47, 0.58, 0.53, 0.57, % 0.15 0.15 0.15 0.17 Surfactant 195, 1.51, 4.06, 2.42, g, % 0.49 0.80 0.71 Surfactant Q-23.73, 5022, g, % 1.11 Total foam 309.2 379.9 342.7 334.6 ingredients,. g a After addition of 145.2 g of Mondur MR, 1.1 eqniv. ~~~
~
~~
~
303.4
351.7
~~~~~~
~
~~~
348.5
346.0
344.0
~~~~~
Table 11. Foam Properties Foam formulations from Table I Propertie,
A
Bd
Cd
Dd
E
Compressive 39.8 33.4 39.4 46.5 33.9 strength (parallel),5 psi 2.04 2.10 2.05 2.13 1.84 Density,* lb/ft3 0.16 0.16 0.17 0.15 0.31 Cell size, mm Flam3 . 9 in./ SE; 1.0, mabi1ity;c min 34 in., sec a ASTM D 1621; at yield. * ASTM D 1667. ASTM D A and are reported in the experimental part of this report'.
F
G
H
I
J
K
42.0
48.8
47.5
33.9
41.9
42.9
36.6
1.97
2.20
2.15
1.93
2.00
2.06
2.07
0.28
0.21
0.25
0.16
0.16
0.17
0.16
SE; 1.0, SE; 1.75, 4 . 1 in./ 33 1692-67T.
foams (Papa, 1970, 1972) and the effects of retardant on the flammability of foams containing rosin polyols were tested. For this study, a reactive glycol-Fyrol 6 (12.4% phosphorus)-was added in varying amounts as part of the glycol mixture. Experimental Section
Following are abbreviations and descriptions of materials except those reported previously such as OH equiv, glycols, isocyanates, and other terms and chemicals (Hedrick, 1973). Fyrol 6, 0,O-diethyl-N,N-bis(2-hydroxyethy1)aminoethylphosphonate, was obtained from Stauffer Chemical Co., S e w York, N. Y. 10017. Silicone surfactant 195 and surfactant Q2-5022 were from Dow Corning Corp., Midland, Mich. Rosin polyol A, OH equiv 214, and rosin polyol B, OH equiv 187, are glycols corresponding to rosin VIb and VIc, respectively, reported previously (Hedrick, 1973). Stocks of poly01 blends A-L, Table I, were prepared in sufficient quantity to make 3-4 gal of foams of each blend (800-900 g of blend). Ingredients were mixed in a closed container and heated to 80-85" when required to dissolve materials. The mixtures were stored at 20-23". 320
Ind. Eng. Chem. Prod. Res. Develop., Vol. 12,
No. 4, 1973
47 d
min
1
SE; 0.6, SE; 0.8, SE; 0.8, SE; 1.4, 34 36 33 31
Burning properties for foams B-1) were unlike those of foam
For foams, enough poly01 blend and isocyanate to give 210 g of polymer mixture were weighed into 1-qt paper ice cream cartons, mixed for 10-20 sec and poured into gallon ice cream cartons for foaming. The time of mixing depended upon the reactivity of the particular mixtures. The blends were only slightly viscous and were readily mixed when added to the isocyanate. Foam properties are tabulated in Table 11. Burning data for foams B-D were as follows: 50% of the specimens of foam B were self-extinguishing and those t h a t burned had a burning rate of 4.9 in./min; similarly, the data for C and D were 3001, and 5.0 in./min and 40% and 3.9 in./min, respectively. See Table 11, footnote d. The ASTM D1692-67T method used for flammability tests covers a small-scale laboratory screening procedure for comparing relative flammability of plastic sheeting and cellular plastics. This test was designed to be used solely to establish relative burning characteristics and should not be used for fire hazard classifications. I n reporting results, the term self-extinguishing (SE) at present is being eliminated from ASTM terminology. This term is used in this report because it gives meaning to the results not espressed in figures normally used to describe burning rates. The term should not be considered out of con-
text and results reported should be qualified by the test method used to obtain them. Discussion of Results
The objective of this work is to study the flammability of foams to determine if the resinyl moiety of resin acids influenced the burning character of rosin poly01 derived foams. Accordingly, foams were made with and without rosinderived polyols and with and without Fyrol 6, a reactive fire retardant containing phosphorus. Foam formulations are tabulated in Table I and most of the results are tabulated in Table 11. All of the formulations are new. KO difference was observed between silicone surfactant 193 used in previous work and silicone surfactant 195. The descriptive literature for surfactant 195 states that it “promotes the miscibility of fluorocarbon blowing agents and their retention by foam” and presumably was better in these respects than surfactant 193. Accordingly, surfactant 195 was used in all the formulations except that for foam D. I n prior work, foams with good cell structure were not obtained with some of the rosin polyols including blends containing rosin polyol B. I n the present work, surfactants 193 and 195 when used with polyol B gave poor foams having large cells. Surfactant Q2-5022-a new material-however dispersed the ingredients used in foam D and good foams were obtained. The cell size on foams A-D were small and quite uniform. Large quantities of Fyrol 6 in foams E , F, and I gave more fluid polyol blends, slightly larger cells, and less dense foams than obtained when small amounts or no Fyrol 6 were used. Foams I-L also had small, fairly uniform cell structures. The formulation of foam C was similar to foam formulation H (Table I11 of Hedrick, 1973). However, to reduce the flammability characteristics expected because of the resinyl group, the rosin polyol concentration in the glycol mixture was increased from 55 to 65% in polyol blends C, D, and I-L. Foam B was made from a glycol mixture consisting of 70% rosin polyol A, in order to increase the concentration of the rosin derivative even more, and T P 440 which was considerably less viscous than PeP 450. This mixture gave a more fluid blend than obtainable from PeP 450. Poly01 blends with these increased concentrations were easily mixed and higher concentrations could be used in mechanical foaming machines. Rosin poly01 B was made by ethoxylation of an extract of a rosin-formaldehyde reaction product and contained a higher concentration of hydroxymethylated resinyl derivatives than polyol A. Normally, rosin contains 10-15% of “neutrals” (nonacidic materials). Extraction removed most of the neutrals and some of the unsubstituted resin acids present in poly01 A. The neutrals in foam C undoubtedly would have a plasticizing effect and may contribute to the flammability of the foam. The differences in compressive strengths and p o s sible flammability of foams C and D indicate this to be the case. The low compressive strength of foam B compared with foam C can be attributed to less cross-linking and to a glycol mixture having a considerably higher average OH equivalent than the glycol blend used for foam C (185 and 152, respectively). A slightly higher concentration of neutrals also may have had some effect. Burning tests show that foams B-D are somewhat less flammable than foam A because of the number of specimens of the foams used in the burning tests that were SE. None of the specimens of foam h had this property. Of the three, foam B had the greatest number of SE specimens. This cannot be explained because of the unknown effects due to differences in composition. Foam B contained the greatest amount of neutrals and its concentration
of resinyl materials was higher than that of foam C and lower than that of foam D ; foam B also contained a different commercial glycol, T P 440. Only rosin poly01 A derived foams, such as foam C, Table 11,were used to determine the effectiveness of the retardant in foams. Since Fyrol 6 was so effective in reducing flammability of rosin-derived foams, studies with formulations such as B and D modified with retardant were not considered necessary or of importance a t this point in the development of these materials. The data from burning specimens of foams E-H, which contained Fyrol6, are about as expected and are similar to some published data of foams containing this retardant (Papa, 1972). Burning data of specimens of foams I-L reflect differences in Fyrol 6 concentrations and show that this retardant has a greater effect on the flammability of rosin poly01 derived foams than on foams which do not contain the rosin glycol. Only 1.5% or less of Fyrol 6 was required to obtain 100% SE foams with the rosin polyols but none of the controls, foams E-H, were SE a t this level. About twice as much retardant was required to get comparable performance in the controls. Also, rosin polyol derived foams containing 3y0 retardant were about as fire resistant as the control with 5-7.5% retardant. The mechanism of flame retardancy of polyurethane foams although of importance has been largely neglected. Much work has been done on the use of halogen- and phosphoruscontaining retardants and in the development of heatresistant organic polyols. Approaches to nonflammable foams have been largely empirical and development of an understanding of fundamental principals of fire retardation has been lacking (Papa, 1970). The flammability results reported here also are empirical. To correlate burning with composition is not possible. I t is believed, however, that the resinyl moiety had some beneficial effect on foam flammability and that this property is related to the condensed-ring system of the resin acids present. Conclusions
Rigid polyurethane foams containing high concentrations of a rosin-derived polyol were tested for flammability. The burning of rosin-derived foams, with and without Fyrol 6, was compared with rates of foams also with and without Fyrol6 made from commercial glycols. When examined by the ASTM 1692 test, rosin-derived foams without Fyrol 6 showed indications of being less flammable in that a greater number of foam specimens were self-extinguishing than obtained from specimens from the other type of foam. There were no S E specimens in the latter case. Flame-retarded foams required less Fyrol 6-about half-when made from rosin polyols than when made from commercial glycols. This evidence indicates that the rosin-derived glycols contribute fire retardancy to foams. Foam formulations with adequate fluidity having higher concentrations of rosin polyols than previously reported were prepared. Use of surfactant Q2-5022 solved the large cell structure problem experienced earlier when foams were prepared from a rosin glycol like polyol B. These changes are considered improvements over what had been reported. Literature Cited
Darr, W. C., Backus, J. K., Ind. Eng. Chem., Prod. Res. Develop., 6,167 (1967).
Hedrick, G. W., ibid., 12,246 (1973). Papa, A. J., ibid.,9,479 (1970). Papa, A. J., zbid., 11,379 (1972). RECEIVED for review June 11, 1973 ACCEPTEDSeptember 5 , 1973 Mention of commercial products is for identification only and does not constitute endorsement by the U. S. Department of Agriculture over those of other manufacturers. Ind. Eng. Chem. Prod. Res. Develop., Vol. 12, No. 4, 1973
321
