FROM SUBSTITUTED
PHENOL S
1 0 0
200
FIGURE I CONDENSATES
WITH COMMERCIAL
RESIN S
/ y
/
© //
s *
C
y
FIGU
/ #
R E 2.
/ /
S L L U W
/ POINT OF CONDENSATES
35 PARTS PHENOLIC RESIN 75
length of the molecules, whereas solubility is influenced not only by the size of the polymer but also by the type of groups attached to the phenolic molecule.
C O N D E N SA TE S F R O M S U B S T IT U T E D P H E N O LS Since the commercial resins had been found to vary consider
ably in behavior, resins from several substituted phenols were prepared. Condensation of a large number of substituted phenols with formaldehyde (S) has shown that heat-rcactive resins
are formed when the condensation is carried out in alkaline media. Reactive resins were made by condensing 1 mole of the phenol with 2 moles of 37% formaldehyde for 6.5 hours at 70° C.
using enough 10% sodium hydroxide solution to dissolve the sub
stituted phenol. One half mole of sodium hydroxide was re
quired in the case of phenylphenol, much less with the others.
At the end of the heating period, the batch was cooled to room temperature and made definitely acid (pH 4) with dilute acetic acid. The oil layer which settled out was separated. This still contained water and a resin content of 60-80% which was deter
5 0 PHENOLIC 7 0 RESIN
mined by drying a sample at 110° C. The yield of dry resin was approximately 110% of the weight of the phenol used.
Enough of the oil layer to give 35 parts of resin was added to 100 parts of wood rosin by the method described above. Addi
tion of the resin at 125° C. was slower because of the greater difficulty in volatilizing the water in the resin. Condensates were also made with 75 parts of phenolic resin.
The viscosity of a 60% by weight solution of the condensates in toluene is shown in Figure 3, and the cloud points at 50% solids in white mineral oil (104° C. aniline-point, critical solution tem
perature) are shown in Figure 4. With smaller groups in the ring the condensates are more viscous and less soluble. The phenyl group apparently has less solubilizing effect than the isopropyl group
Co n d e n s a t e s w i t h Ma t e r i a l s Ot h e r Th a n Ro s i n. It appears that rosin has an unusual fluxing action on phenolic resins. Several related materials were used with a reactive resin made from butylphenol. Seventy-five parts of the phenolic resin were condensed with 100 parts of the fluxing agent. The results follow:
Fluxing Agent Rosin
Limed rosin Hydrogenated rosin Polyterpene resin
Viscosity of Condensates (6 0 % in Toluene),
Poises at 25° C.
143 129 3 6
The much lower viscosity obtained with hydrogenated rosin which still contains approximately one double bond instead of two double bonds which are present in abietic or I-pimeric acid is remarkable'. The high viscosity obtained with limed rosin also suggests that the carboxyl group is not involved. Methyl abietate gives viscous condensates. The polyterpene resin is produced from pinene, and the condensates are low in voscosity.
This behavior suggests chemical combination between rosin and the phenolic compound, and subsequent work described in this study provides additional support for this theory. Hultzsch (4) suggested the formation of a chromane derivative from phenol alcohols and unsaturated compounds, and reports the condensation of a substituted saligenin with abietic acid:
+ iio < 0 - ch ’- < 3 oh
1 CH iO II CH jOH
H ,C — C — CH , H
Abietic acid Dialcohol
While the saligenin-type materials may condense with rosin, it appears that the phenolic resin must be further polymerized to give highly viscous condensates, as will be shown below.
Co n d i t i o n sf o r Fo r m a t i o n o f Re a c t i v e Ph e n o l i c Re s i n s. p-ieri-Butylphenol was studied as the starting material for the reactive resin. Several catalysts were tried, but sodium hydrox
ide was found to be generally satisfactory; 0.05 mole per mole of butylphenol was found to be sufficient, but progressively more reaction occurred when 0.1 and 0.2 mole were employed. Two moles of formaldehyde were used per mole of butylphenol, and it was found that 85-90% was usually consumed in the reaction.
With smaller amounts of formaldehyde the condensates with rosin were less viscous. With 1.5 moles of formaldehyde and less, the decrease in viscosity was very pronounced.
Honel (S) showed that when less than 2 moles of formaldehyde is used with 1 mole of butylphenol, the melting point of the con
densate with ester gum (rosin glyceride) decreases. When an excess above 2 moles of formaldehyde is used, no appreciable increase in melting point is noted. An increase in melting point of condensates is accompanied by increase in viscosity in solution.
In the following work 2 moles of formaldehyde were used.
The effect of time and temperature was studied, using 2 moles of 37% formaldehyde per mole of butylphenol with 0.05 mole sodium hydroxide as a catalyst. The reaction was carried out at 25°, 75°, and 100° C., and 35 parts of the resin were added to 100 parts of rosin in the usual manner. The viscosities of the condensates (60% in tolene) are shown in Figure 5).
The resins prepared at 25° C. had not been carried far enough.
One sample run for 50 hours at 25° C. gave a slightly higher vis
cosity. Since the phenol alcohols are believed to be the chief products at this temperature, it appears that a higher stage of condensation in the resin is required for the most viscous conden
sates. At 75° C. the viscosity of the condensate reached a maxi
mum at 6.5 hours. Longer or shorter periods produced conden
sates of a lower viscosity. At 100° C. the 2-hour sample was apparently beyond the maximum, and the 4-hour sample gave a still less viscous condensate.
These results again suggest combination of the phenolic resin with rosin. If the rosin acted only as a solvent, it would be diffi
cult to explain the maximum observed, since the phenolic resin is completely soluble in all cases. It appears that to impart maximum viscosity the phenolic resin must be somewhat poly
merized but must still retain the ability to condense with rosin.
This maximum viscosity has been observed (5) when reactive resins are dispersed in drying oils.
USE O F T R IR E A C T IV E PH E N O LS
Resins from butylphenol give condensates that are somewhat more viscous than those made with the corresponding amount of commercial resins (Figure 1). However, the viscosity still falls short of the desired result. Phenols with three positions which could be condensed with formaldehyde, such as phenol, m-cresol.
and 3,5-xylenol, give reactive resins which cannot be fluxed with rosin since they separate as infusible precipitates. However, mixtures of tri- and direactive phenols were condensed with formaldehyde, and the resulting reactive resins could be con
densed with rosin to give homogeneous soluble resins of ex
tremely high viscosity. Resins whose viscosity in 60% solution in toluene was well over 100,000 poises have been made by this method, and the viscosity of the condensate can be adjusted al
most at will. The catalyst, the ratio of formaldehyde to phenol, and the extent of the reaction all have a definite effect on the phenolic resin produced. The percentage of trireactive phenol used is of even greater influence, and the content of such phenols must be accurately known to determine the type of resin that will be formed. If phenols with but one reactive position are present, such as 2,4-xylenol, the activity of the resin is greatly reduced.
In this study only direactive (p-cresol and butylphenol) and tri
reactive (m-cresol and phenol) materials were used. Bisphenol was also studied and found to behave like a trireactive phenol, since it may be regarded as the first product in forming a resin from phenol.
November, 1944 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
F IG U R E 7.
CLOUD. POtN T CONDENSATES FROM
u-t p£ R E S O L S /
PARTS 3 0 PHENOLIC 40 RESIN 50 F IG U R E 6.
D/-& TRIREACTIVE) PHENOLS
F IG U R E 6.
PH EN O L - BUTVLPHENOL
The conditions for the reactive resins were studied, and the results of the time-temperature study for a mixture of 1 mole of phenol and 3 moles of butylphenol with 8 moles of formal
dehyde are shown in Figure 6. Fifty parts of reactive resin were condensed with 100 parts of rosin. No evidence of a maximum viscosity, such as was noted with butylphenol (Figure 5) was found. The resin heated for 6 hours at 95° C. gelled before it '•ould be dispersed in rosin.
The conditions for preparing the condensates were modified slightly because of the greater reactivity of the phenolic resins.
Because of the much higher viscosity of the condensates, resin was added to rosin at about 90° C., and the temperature gradu
ally raised to remove the water which was present with the resin.
After the water was evolved the temperature was raised, and at about 180° C. a further evolution of water and formaldehyde was accompanied with a sudden increase in viscosity. Vigorous stirring was essential throughout the condensation. The tem
perature was then raised rapidly to 250° C. where the conden
sate was fluid, except in the case of the most viscous condensates which barely flowed at that temperature.
While condensates of considerably higher viscosity are ob
tained if the reaction between phenol and formaldehyde is car
ried well along, it has been found that less advanced resins are more readily separated from water, and their condensation with
rosin is much simpler. Therefore, in most of the work the resin was made by cooking for 6 hours at 75° C. Since various phenols differ greatly (7) in the rate at which they react with formalde
hyde and also in the rate of further condensation, a more ex
tensive study of the time and temperature of reaction may reveal better conditions with individual mixtures.
Mixtures of m- and p-cresol were condensed with formaldehyde and the resulting resins condensed with twice their weight of rosin. These condensates were much less soluble than those pm- pared from commercial resins. The cloud point was determined at 70% concentration in white mineral oil (104° C., critical solu
tion temperature in aniline). The results are shown in Figure 7.
These condensates are much less soluble than the commercial modified phenolic resins, and they are also much more viscous.
It will be noted that the cloud point increases as the content of the trireactive phenol is increased.
Many combinations of di- and trireactive phenols were con
densed with formaldehyde, and the resulting resins were con
densed with various amounts of rosin. Figure 8 summarizes the viscosities of the (60% in toluene) condensates of a large number of such resins with rosin. These resins were made from mixtures of phenol and butylphenol (2 moles of formaldehyde, 1 mole of the blend of phenols, 0.05 mole of soldium hydroxide) and condensed for 6 hours at 75° C. The resin was acidified at FIGU RE 5.
BUTYLPHENOL RESINS
1 0 , 0 0 0
I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 36, No. 11 room temperature and the water layer separated. The resin
layer was not dried but was condensed with rosin as outlined above, alter determining solids at 110° C. to estimate the resin content. The percentages shown on the curves are in mole per cent of trireactive phenol.
It will be readily seen that a wide variety of highly viscous resins can be prepared. If bisphenol or m-cresol is substituted for phenol, the resulting products have approximately the same viscosity, as is the case when p-cresol or amylphenol is substituted for butylphenol. The cloud point is lower when larger side groups are present.
U T IL IZ A T IO N O F C O N D E N SA TE S
The condensates in Figure 8 cannot be esterified with glycerol.
Attempts to form the glyceride led to insoluble gels before the acidity was greatly reduced. Here again is an indication of com
bination of the phenolic resin and the rosin. If the rosin acted only as a solvent, there is no reason to expect gel formation if it is converted to an ester. However, if the rosin acids are combined with the phenolic resin to form dibasic acids, gelation on esteri- fication with glycerol would be expected.
The resins can be dispersed in linseed or soybean oil (<?) without too great difficulty, but because of their high viscosity they do not dissolve quickly. After heating for some time at 250° C.
or higher with the oil, it is possible to add glycerol and neutralize the resin acidity. Acid interchange has occurred with the oil,
and gelation is prevented by the presence of the fatty acids in the ester structure. The viscosity of the resulting varnish is high, as might be expected from the highly viscous rosin that is dis
persed in it.
These highly viscous resins cannot therefore be utilized as the usual modified phenolic resins, but when processed in the manner outlined above hold promise of becoming useful varnish resins,
A CK N O W LEDG.M ENT
The author wishes to thank J. K. Wise, V. A. Navikas, A. R.
Shoff, and A. S. Hussey who carried out the experimental work.
L IT E R A T U R E C IT E D
(1) Albert, K., and Berend, C., German Patent 254,411 (1910).
(2) Gardner, H. A., and Sward, G. G., "Physical and Chemical Examination of Paints, Varnishes, Lacquers and Colors", 9th ed., p. 216, Washington, Inst, of Paint and Varnish Re
search, 1939.
(3 ) Honel, H., J. Oil Colour Chem. Assoc., 21, N o . 218, 247 (1938).
(4) Hultzsch, K., J. prakt. Chem., 158, 275 (1941).
(5 ) Powers, P . 0 . , Ind. En q. Chem., An a l. Ed., 14, 387 (1 9 4 2 ).
(6) Powers, P . O ., U . S. Patent 2,345,357 (1944).
(7) Sprung, M . M „ J. .4m. Chem. Soc., 63, 334 (1941).
(8) Turkington, V. H., and Allen, I., In d. En o. Chem., 33, 966 (1941.)
Pr e s e n t e d before the Division o f Paint, Varnish, and Plastice Chemistry at the 108th Meeting o f the Am e r i c a n Ch e m i c a l So o i e t t, New Y ork, N. Y.