PVC Plasticizers from Turpentine B.
H.
Check list for PVC plastics plasticized
SUMMERS and G. W. HEDRICK
Industrial Crops Laboratory, Naval Stores Research Station, Olustee, Fla.
with alkyl pinonate esters
F. C. MAGNE and
good thermal stability
4 4
resistance to fungus attack
/'
stability to u/travio/et light
R. Y.
MAYNE
Industrial Crops Laboratory, Southern Utilization Research and Development Division, U. S. Department of Agriculture, New Orleans, La.
good plasticizing action
OXIDATION
of a-pinene with ozone or permanganate yields pinonic acid, which can be readily converted by hypohalite to pinic acid. -4number of dialkyl pinates have been evaluated as plasticizers for poly(viny1 chloride) ( 5 , Q), and plasticizing and fungi-resisting properties of certain esters of pinonic acid in cellulose acetate (6, 7) examined. Neither resistance to fungal attack on poly(viny1 chloride) plasticized with higher alkyl pinonates nor plasticizing properties of these esters in poly(viny1 chloride) have been reported. Experimental Procedure
Pinonate esters were made by a method not previously used on pinonic acid (6>8 ) . Crude acid (184 grams) was dissolved in 600 ml. of toluene containing 200 grams of tridecyl alcohol and 10 grams of p-toluenesulfonic acid. This was heated to reflux and water was removed as an azeotrope. Esterification was complete (95 to 1007,) in about 2 hours, and after being washed with water and 5y0 sodium carbonate solution, the product was distilled twice through an 18-inch Vigreux column
Distillation of the glycerol and pentaerythritol esters was not possible, and these were decolorized and stripped of solvent a t 200' C. in a vacuum (0.5 mm. of mercury). Acid number, refractive index, molecular refraction, and density were determined. Crude ester yield was 90 to 95y0 of theory. Benzene, p-cymene, carbon tetrachloride, and chloroform were satisfactory replacements for toluene. With lower boiling solvents, the reactions were slower and required reflux for about 24 hours. There was an improvement in color with these solvents, particularly with chloroform. The colors ranged from colorless to a light amber. .411 the pinonate esters in Table I have been screened as plasticizers for Vinylite VYDR copolymer and the best evaluated in Geon 101. T h e formulation used (weight per cent) is: polymer or copolymer 63.5; plasticizer 35.0; stearic acid 0.5; and basic lead carbonate 1.0. These formulations were milled and molded at 310' F. T h e procedures followed in these operations, in preparing the test specimens and various tests, except for volatility, have been described (70). Volatilities were
determined by the activated carbon method (ASTM D 1203-521'). I n the case of the lauryl and tridecyl pinonateplasticized Vinylite VYDR stocks. the volatility loss was carried through a second cycle to ascertain if there was a change in volatility rate.
Volatility Loss over Two Heating Cycles %> Loss" Plasticizer L a u r y l pinonate T r i d e c y l pinonate D i o c t y l phthalate a
First cycle
Second cycle
1.40 2.10
1.0 1.8 0.9
0.90
M i l l e d sheet 18 t o 20 mils t h i c k .
Samples of Vinylite VYDR copolymer plasticized with lauryl and tridecyl pinonates, di-2-ethplhexyl phthalate (DOP), and unplasticized material were sterilized. inoculated with Aspergillus ni~cer and Aspergillus oryzae, and incubated at 28" to 30°, 80 to 90% relative humidity, for 21 days (13). Little growth was observed on any specimens. A second test, somewhat similar to one already described (4, demonstrated
A
B
C
Figure 1. Little growth was observed on specimens where plasticizers were sole carbon source
Figure 2. Growth was not inhibited b y plasticizers in a complete medium
A. Lauryl pinanate, slight growth. 6. C. Di-2-ethylhexyl phthalate, no growth.
Tridecyl pinanate, no growth. Basal medium. E . Dextrose
A. l a u r y l pinonale. B. Tridecyl pinonote. C. Di-2-ethylhexyl phthalate. D. Complete medium only. E. Calcium propionate
Left plate o f each set inoculated with Aspergillus oryzae, and right set
l e f t plate o f each set was inoculated with A. oryrae, and right plate with A. niger
with Aspergillus niger
D.
VOL. 51, NO. 4
APRIL 1959
549
that the plasticizer could be used as the sole carbon source for the fungi. T h e plasticizers were mixed with a basal medium of salts in a n amount equal to 0.870 carbon, inoculated with A . niger and A . oryrae, and incubated for 14 days. They were compared with dextrose as a carbon source and the basal medium alone (Figure 1). The lack of fungistasis of the two pinonates and D O P with a good carbon source was compared with calcium propionate, which is a moderately strong inhibitor for A . niger and retards early growth of .4. oiyroe (Figure 2). Discussion
Fairly large scale preparations of pinonic Pcid 3-acetyl-2,2-dimethylcyclobutaneacetic acid have been reported ( 9 ) . An improvement in this procedure results in a purer product (74). Crude pinonic acid made from a commercial a-pinene CYD+~O,consists of cisand trans-d.l- and cis- and tram-d-pinonic acid. Addition of acetone results in precipitation of pure cis-d,l-pinonic acid, melting point 103.5" C. Freeing the filtrate of acetone after removal of the solid isomer gave a liquid which was slo~v to crystallize. There was no difference in physical properties of the tridecyl esters of pure cis-d,l-pinonic acid. the liquid, and crude acid mixture.
These similar physical properties can be explained by the presence of about 5% of enol in pure methyl d,l-pinonate ( 8 ) and the tautomeric equilibrium of the geometric isomers of pinonic acid (7, 2). Consequently, regardless of whether the pinonic acid was pure cis or a mixture of cis and trans isomers. the ester represented an equilibrium mixture of constant composition. .As pinonic acid and its esters are particularly unstable in acid medium and undergo rearrangement to form homoterpenyl methyl ketone (1. 77; 72). it is surprising that yields are almost quantitative. T h e plasticizer screening indicates that iso-octyl. decyl? lauryl. and tridecyl esters are good plasticizers for Vinylite VYDR resins, and except for high volatility, nearly as good as DOP-especially the lauryl ester. T h e lauryl and tridecyl esters when used to plasticize Geon 101 are compatible and give about the same results as obtained with the copolymer. T h e volatility loss of Vinylite VYDR plasticized jvith 1aur)-1 and tridecyl pinonates Lvhen redetermined was less for the second heating cycle; this indicates the presence of some volatile impurity in the plasticizer. On this basis the true volatility loss of lauryl pinonateplasticized stock approaches more closely D O P than is indicated by Table 11. T h e hydronopyl and ethylene glycol
I. Physical Properties of Esters of Pinonic Acid Boiling Point Density, Refractive Molecular Refraction O C. Mm. Hg dz04 Index, n%O Found Calcd.
Table
Alcohol Iso-octyP Decyl" Hydronopolh Tridecyl" Octadecyl' LaurylC Ethylene glycol' Glycerol' Pentaerythritol" a
165-172 147-8 170-5 165-171 218-227 172-192 220-225
... ...
Enjay alcohols.
Table
0.9495 0.9388 1.0101 0.9313 0.8947 0.9223 1.0726 1.1029 1.1131
0.9 0.4 0.5 0.2 0.6 0.4 0.3
... ...
Glidden (3).
1.458 1.459 1.4872 1.4522 1.4565 1.4601 1.4781 1.4865 1.4948
85.07 94.49 95.134 108.08 132.59 104.55 103.25 153.69 209.50
85.52 94.83 95.41 108.77 132.01 104.13 103.33 154.11 209.24
Eastrnan Organic Chemicals.
II.
The Pinonate Esters W e r e Screened as Plasticizers Tensile Brittle Strength, 100% Elongation, Point, Volatility Plasticizer, 35% P.S.I. Modulus % O C. Loss %"
Vinylite VYDR Copolymer Lauryl ester Tridecyl ester Iso-octgl ester Decyl ester Hydronopyl ester Ethylene glycol ester D O P controlb Glycerol ester, D O P 1-1 Pentaerythritol ester, D O P 1-1 Octadecyl ester, DOP 1-1 Octadecyl ester, T C P 1-1 T C P control"
2730 2870 2770 2780 3120 3230 3030 3290 3380 2900 3190 3510
1430 1490 1240 1260 2090 2050 1630 2380 2830 1990 2300 2420
320 350 340 340 330 300 300 300 280 340 340 280
- 41 - 29
- 27 -31 + 1 - 1 - 33 - 1 + 5
-31 -31 0
0.73 0.90 3.00 1.80 0.50 0.33 0.35
... ... ... ...
Geon 101 Homopolymer Lauryl ester Tridecyl ester D O P controlb a Molded stock 70 mils thick. stock 1s to 20 mils thick.
550
2820 3050 3090
1480 1580 1740
Di-2-ethylhexyl phthalate.
INDUSTRIAL AND ENGINEERING CHEMISTRY
1.6d - 39 1.7d - 31 - 35 1.0d Tricresyl phosphate. Milled
330 350 330
esters are not so good as DOP. The glycerol and pentaerythritol esters, although compatible, resulted in stocks too stiff to test. Blends of these esters with D O P are not effective plasticizers and give poor flexibility. The blended plasticized stocks exhibited physical characteristics which, except for flexibility, are about the same as for tricresyl phosphate (TCP)-plasticized stock. Octadecyl pinonate and its blends with D O P or T C P were incompatible. T h e initial thermal stability of stocks plasticized with lauryl or tridecyl pinonate is somewhat poorer than D O P stocks during the first hour of exposure, but better than the control after this initial exposure. Copol\-mer specimens plasticized with lauryl pinonate seemed to show better ultraviolet stability than samples plasticized with D O P . Many plasticizers are attacked by numerous fungi and bacteria; others resist attack by microorganisms ( 4 ) . '4preliminary study shows lauryl pinonate and tridecyl pinonate-plasticized \'inylite VYDR stocks to be as resistant to the growth of two test organisms as a D O P plasticized specimen and a n unplasticized sample. Little growth was observed on any specimens. I n a test to show lack of growth support by the plasticizers, tridecyl pinonate \vas not utilized in 2 weeks as the sole source of carbon by the two fungi, and lauryl pinonate was used very sparingly in that time. Neither chemical acted as a fungistat in amounts equal to 0.87c carbon. literature Cited (1) Arcus, C. L., Bennett, C. J., J . Chem. SOC.1955, p. 2627. (2) Baeyer, Ber. 29, 326 (1896). (3) Bain, J. P., J . Am. Chem. Soc. 68, 638 (1 946). , ~ .- , .
(4j Berk, S., Ebert, H., Teitell, L., IND. ENG.CHEM.49, 1115 (1957). (5, Conyne, R . F., Yehle, E. A., Ibid., 47, 853 (1955). (6) Hasselstrom. T..U. S. Patent 2.679,461, , . . 2,679,509 (1954).' 17) Hasselstrom. T.. Balmer. C. E.. Kennedy, N.'E., Coles, H. 'W., Tappi 77. -538 - - (1950). I
\ - - - - ,
(8jLe-Van-Thoi, Ann. chim. 10, 35 (1935). (9) Loeblich, V. h?., Magne, F. C., M o d , R . R., IND.ENG.CHEM.47, 855 (1955). (10) Magne, F. C., Mod, R. R., Ibid., 45, 1546 (1953). (11) Parkin, B. A , , Hedrick, G. W., J Am. Chem. Sor. 80, 2899 (1958). (12) Simonsen, J., Owen, L. N., "The Terpenes," 2nd ed., vol. 11, p. 147, University Press, Cambridge, 1949. (13) Vicklund, R. E., Manowitz, M., Engineer Research and Development Laboratories, Fort Belvoir, Va., Rept. 1118, Pt. 1 (April 1949). (14) Wielicki, E. A,, Boone, C. J . , Evans, R. D., Lytton, M. R., Summers, H. B., Jr., Hedrick, G. IV., J . Polymer Sci., in press. RECEIVED for review July 18, 1958 ACCEPTED November 3, 1958 Trade names are not to be considered a recommendation for the use of the materials by the U. S. Department of Agriculture.
