March 1950
INDUSTRIAL AND ENGINEERING CHEMISTRY
7.8 6.6
3 x
5.4
6‘ 3.0 3
\
1.8 x
0.6 -20
Figure 6. X = TCP
-10
1
0 10 Temperature,
20 C.
30
40
60
Comparison of Plasticizers at Various Temperatures by 1000-Second Compliance 45% plasticizer 0 = Butadeo A = Hexadec 0 = Octadec 0 = Caprahex W = Butahex A = Hexahex
=
TOP
those diphosphate esters which are superior or comparable to TOP in creep, are, nevertheless, somewhat poorer than anticipated, on the basis of their dimeric structure. The greater plasticizing effectiveness of the decamethylene glycol derivatives as compared to the hexamethylene derivatives is probably due to the former being better solvents for Geon 101 (9). Furthermore, as noted previously, the butylene glycol derivatives exhibit limited compatibility wjth the base resin. Presumably, increasing the glycol linkage from 4 to 6 to 10 results
491
in the formation of products which are superior solvents for Geon 101. Whether or not ten carbons is the optimum length for the glycol bridge has not been specified. Table I1 shows that the diphosphate ester plasticized films exhibit a somewhat greater elongation a t break than the standards. The tensile strengths of both the standard and diphosphate ester plasticized films, on the other hand, are fairly uniform and appear unaffected by plasticizer type. This result is quite different from results on tensile strength measurements (3) for the liquid polymer plasticized films, where limited increased softening action was reached a t 25% plasticizer content. Although no measurements of volatility loss of plasticizer from the resin were made, it is reasonable to assume that the compatible diphosphates will be more permanent than conventional monophosphate plasticizers. The increased molecular weight and consequent lower vapor pressure of the diphosphate esters should enhance the performance of these materials in this respect. LITERATURE CITED
(1) Aiken, Alfrey, Janssen, and Mark, J . Polymer Sci., 3, 178 (1947). (2) Alfrey, Wiederhorn, Stein, and Tobolsky, J . Colloid Sci., 4, 211 (1949). (3) Ali, Mark, and Mesrobian, IND. ENQ.CHEM.,42,484 (1950). (4) Atherton, Openshaw, and Todd, J . Chem. SOC.,1945, p. 382; 1948,p. 1106. ( 5 ) Clash and Berg, Modern Plastics, 21, 119 (1944). (6) Cook, McCombie, and Saunders, J.Chem. Soc., 1945,p. 873. (7) Gerrard, Ibid., 1940,p. 1464. (8) Reed, IND.ENG.CHEM., 35,896 (1943). RECEIVED October 28, 1949. Presented before the Division of Paint, Varnish, and Plastics Chemistry at the 116th Meeting of the AnmRIcAN CHEMICAL SOCIETY. Atlantio City, N. J. Portion of thesis submitted t o the Polytechnic Institute of Brooklyn by R. H. Oliver in partial fulfillment of the requirements for the degree of master of science in chemistry.
Use of Amine Additives to Prevent Drying Loss on Aging A. C. ZETTLEMOYER AND DONALD M. NACE National Printing Ink Research Institute, Lehigh University, Bethlehem, Pa.
To prevent loss of drying on aging of printing inks pigmented with alumina hydrate lakes, the investigation of hemin, o-phenanthroline complexes of the drier metals, and many other nitrogen-containing additives has been undertaken. The compound DMP-30[2,4,6-tri(dimethylaminomethyl)phenol] has been found to be the most effective and at the same time the most practical agent of those tested. Excess DMP-30 tends to inhibit drying and to accelerate livering; therefore, it should be used only when needed and then only’in amounts of 1 to 2% of the pigment. The mechanism of the activity of DMP-30 has been investigated. The DMP-30 is almost completely adsorbed by the pigment and the amount of cobalt adsorbed is not reduced by its presence. The conclusion is reached that DMP-30 is effective because it changes the acidic nature of the pigment surface.
D
ECREASE of drying rate on aging is a phenomenon re-
stricted to certain paints and printing inks which dry by oxidation and polymerization upon exposure to air in thin films. When certain pigments are used, the paint or printing ink may dry satisfaetorily soon after it is made up, but after storage for
several weeks or months it may dry slowly or not a t all. Apparently, the pigment adsorbs or reacts chemically with the drier metal, and thus the drier is removed from the vehicle and ita activity lost. Among the offending pigments are titanium dioxide, alumina hydrate lakes, and long carbon blacks. In an earlier report (8) it was shown that drier loss could be counteracted by the use of a feeder drier consisting of an insoluble cobalt compound feeding drier metal into the vehicle to replace that lost to the pigment. The present report contains the results obtained by the use of nitrogen-containing compounds. These studies have been concentrated on the alumina hydrate lakes because of their wide use in printing inks and the intensity of the drier loss frequently encountered with them. The long carbon blacks seem to present a distinct problem not solved by the remedies discussed here. This study of the use of amine additives to attempt to prevent drier loss was prompted by the interesting work of Nicholson (3) on o-phenanthroline-drier metal complexes. The present authors’ consideration of the problem led to the conclusion that hemin, obtained from hemoglobin of the blood, might serve as a suitable drier catalyst which also would not be adsorbed by pigments. This idea of the use of hemin as a drier was supported
492
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 42, No. 3,
These drying tests on hemin compounds were made b j measuring “drop time” on a Gardner drying time recorder (a). Drop time is the time at which drops cease to fall back onto the film from the sprocketted wheel. Investigation of the films after drying showed considerable after-tack. This deficiency plus its high cost makes hemin a drier of only academic intcrest
30 (0
n 3 0
1
20
I I-
OTHER NITROGEN-COKTAINING COMPOUNDS
o
In order to direct the studies toward compounds of practical interest, attention was next turned to the o-phenanthroline complexes of Nicholson ( 3 ) ,and later to simpler amine additives. 0-PHENASTHROLIXE C,OMPLEXES.Contrary to the findings of Xicholson, the cobalt, complex compound gave unsatisfactorv results both in varnish and in inks whereas the manganese complex gave excellent results. Typical results are listed in Table I. .Is in all the authors’ drying tests, films 0.001-inch thick m r e prepared on glass slides and measured on the Gardner recorder. The addition of uncomplexed o-phenanthroline to the inks vias found to give the same results. Lack of solubility of the cobalt o-phenanthroline complex compound was thought t o be respocsible for the poor results, but this was nox definitely proved. used to attempt Results obtained with 5-nitro-o-phenanthroIine, to increase solubility, and with the dipyridyl complex compound were similar.
zt 10
LT
n
0 20
40 AGE
63 IN DAYS
30
Figure 1. Hemin Oleate as Drier in Tartrazine Yellow Lake Ink by the work of biochemists such as Robinson ( 6 ) Fvho first showed that hemoglobin and its derivatives could oxidize drying oils in aqueous emulsions. In addition, the literature revealed that biochemists a t the University of Chicago had reported in 1941 ( 4 ) that the iron-o-phenanthroline complex greatly increased the rate of oxygen absorption of brain tissue. The step from thr naturally occurring hemin to the synthetic complex had bee11 taken. This work of the biochemists was generally overlooked by oil chemists and apparently did not influence Xicholson (3) who found that o-phenanthroline complexes of cobalt, manganese, and lead were efficient driers which prevented loss of drying 011 aging. After some successful experiments with hemiii compounds, these studies were directed toward simpler synt,hetic nitrogencontaining compounds. Early in t’his phase of the work it was learned that the amine could be added directly to the printing inks and did not have to be complexed first with the drier metal. This finding is in agreement with the recent work cf Wheeler
TABLE I.
DRYING Trms
FOR
0-PHEYASTHROLISE COMI’LEXER Time, Hours
-----Drying
Varnish
Ago i n days
0
-----
Yellow Lake Ink 7 43
Drier
0.05% Co as linoleate 0 . Oa% Co as complex 0.06% Bln as linoleate 0.038% LIn as linoleate 0.012% bln as complex
5
13
1
1
18
J
6.0 15 3.5 2.0
18
..
20
6.7 3.2
20 4.0
..
(6).
Particular success in preventing drying loss on aging !vas obtained with 2,4,6-tri(dimethylamiiiomethyl)phenol (trade name DMP-30). Later work was concentrated on the test,iiig of the behavior of DMP-30 in inks pigmented ~ i t h17 study of the mechanism of its action. HEMIN COMPOUNDS
Hemin, which is a part of the protein hemoglobin, makes ul-1 about 1% of whole bleod. A complex porphyrin structure containing iron, hemin is responsible for carrying oxygen in the blood. Since Robinson showed ( 5 ) that hemin compounds were effective in catalyzing the oxidation of drying oils in vitro, it was to be expected that these compounds might’ be effe,ctive driers in printing inks and paints. Furthermore, their comp1:u structure might be expected to inhibit drier loss on aging. The insolubility of hemin mas overcome by preparing the oleate which could be put into a varnish by the use of a mutual solvent which mas then evaporated. Drying tests on a variety of lake inks showed very rapid drying and a dccrease rather than an increase of drying time on aging. Figure 1 indicates the coinparison for the tartrazine yello~vlake ink used in a previous study ( 8 ) . Here the comparison is made with a common drier, cobalt linoleate. The only drier added to obtain the lower curve was 0.05% iron as hemin oleate. Iron driers are not very effective at room temperature so that this amount is exceptionally low. Figure 1 also demonstrates that hemin oleate is effective in preventing drying loss in inks pigmented with other lakes. Recent tests have indicated that the n-hexyl ester of hemin has even more desirable solubility properties than the oleate; drying resulte with it are equally good.
Figure 2. Effect of Variation of Additive-to-Cobalt Ratio on Drying Rate in Varnish A. B. C. D. E. F.
Dieth, larnine Dimethylbenzylamine 2-Aminopyridine Aniline
DbIP-30 o-Phonantliroliue
Arrows indicate scales t o he used with
each
curve
The experiments with such complexes were repeated several times, but the reason for this discrepancy with the work of Sicholson is not apparent. I t is of possible importance that different vehicles were used: Nicholson (3) used alkali refined linseed oil whereas a S o . 1 lithographic .ramiuh was used in this work. [The importance of the acid number of the varnish is indicated by some recently published work by Yicholson ( 7 ) . ] If oxidation and reduction of the drier metal are necessary for drying action, however, it is noten-orthy that the complex cobalt compound would be expected to be stable in the cobaltic state. That is to say, the electron configuration of the cobaltic complex
March 1950
INDUSTRIAL AND ENGINEERING CHEMISTRY
2.5b
I
I
I
I
493
35
I
8- DMP-IO (3EQUIV)
30
C- DMP-IO(6ECIUIV) 0- DMP-IO (IZEQUIV) E- DMP-IO ( 2 4 E Q U I V ) F- DMP-I4 (3EQUIVl G- DMP-I4 C6EWIV)
VI
K 25 2 0 20
=W
I
Q
1.0
0
F
A-6 EQUIV. ORTHOPHENANTHROLINE B-6 E QUIV. S TEARY LDI ME THYLAMI NE
15
0
f
I O
a 0
0.5 0.0
0.01
0.02 0.03 0.04 PERCENT COBALT
5
0.05
Figure 3. Drying Rate a t Different Cobalt Concentrations in Varnish at Constant Additive-toCobalt Ratio
0
IO
20
30
40 50 60 A G E I N DAYS
80
90
100
Figure 5. Effect of DMP-10 and DMP-14 on Drying Rate of Tartrazine Yellow Lake Ink (0.3% Co) 4
C- DICYCLOHEXYLAMINE (6
70
!
I
,
I
*
A-BLANK 6 - D M P - I 8 (3 EQUIV.) C - D M P - 1 8 (6 EQUIV.) D - D M P - 3 0 (4 EQUIV.) E - D M P - 3 0 (I EQUIV.) F - D M P - 3 0 (2EQUIV.) G - D M P - 3 0 (3 EQUIV.)
230 3 0
25
z
- 20 w
I F
15
0
->z 10 a 0
20
I
I
40
60
I
I
I
80 100 120 AGE IN DAYS
I
140
I
160
I
Figure 4. Effect of Various Nitrogen-Containing Additives on Drying Rate of Tartraeine Yellow Lake Ink (0.3% Co) is stabilized so that an oxidation-reduction mechanism involving &he complex would not be expected to take place. Thus, the cobalt would be ineffective by such a mechanism. No such re-striction is imposed on manganese by complexing it with ophenant hroline o-Phenanthroline complexes of iron, chromium, zinc, magnesium, and nickel were also investigated. Only the iron and .chromium complexes gave improvement over the respective oleates and in these cases the drying times were so long that their use would be impractical. Cost also makes the present use of the manganese o-phenanthroline complex compound prohibitive. AMINEADnrTroN. This investigation next turned to a study of more readily available compounds. Since earlier work had .demonstrated that o-phenanthroline could be added directly to the varnish or printing ink, studies were made by simply adding the uncomplexed compound on the %roll mill after the drier was added. For the remainder of the work drying tests were measured by .determining “paper offset time” on the Gardner recorder using a paper strip on the wheel onto which the ink offsets until the film 0.001-inch thick on glass is dry. Fifty-five nitrogen-containing compounds, mostly amines, were studied in both varnish and yellow lake ink. For the initial work in varnish, six equivalents of each compound per equivalent of cobalt were added to a No. 1 lithographic varnish containing 80.02% cobalt. Some additives were found to accelerate the drying rate, others were found to decrease the drying rete. Further tests showed that the drying time varied considerably when the amount of additive was varied. The curves obtained
.
O
5
180
0 0
I
I
I
I
20
40
60
80
I 100
I
120 AGE I N DAYS
I
I
I
140
160
180
I 200
Figure 6. Effect of DMP-18 and DMP-30 on Drying Rate of Tartrazine Yellow Lake Ink (0.3% C o )
for different additives followed different patterns as illustrated for a few examples in Figure 2. In some cases the additive caused an increase, in others a decrease in drying rate; in some cases also a maximum or minimum was produced a t one concentration. Additional tests showed that the amount of change in drying time caused by a certain equivalent weight ratio of that additive compound to cobalt depended upon the actual amount of cobalt present in the varnish. Figure 3 illustrates such variation for two additives with the concentration of cobalt varied and with the ratio of equivalents of additive per equivalent of cobalt fixed at six. For the additive stearyldimethylamine, the shortest drying time occurred at 0.02% cobalt, but for the additive o-phenanthroline the drying time increased as the ooncentration of cobalt was increased. Work with amine additives is further complicated by the fact that results in varnish bear no relation to those obtained in printing inks. This is illustrated in Figures 4 and 5. Both p toluenesulfonamide and DMP-10 (o-dimethylaminomethplphenol), for example, decrease the drying time of varnish by the same amount (lo%), yet the effects of these agents OD the drying time of the yellow lake ink are quite different: 6 hours a t the start with the sulfonamide and about 3 hours with the DMP-IO. Their effects on drying loss on aging are also markedly different. Similar differences were found in the behavior of many othei compounds tested. Eventually the results with DMP-30 given in Figure 6 were obtained. Good results were also obtained with some of the other DMP’s, but large concentrations were required so that these materials are impractical to use. Whereas DMP-18 (o-dimethylamino-
INDUSTRIAL AND ENGINEERING CHEMISTRY
494
methyl-p-octylphenol) was as effective when six equivalents were added to the 0.3% cobalt in the ink as DMP-14 (o-dimethylaminomethyl-p-butylphenol), Figure 5 shows that DMP-10 was less effective a t this concentration. Higher concentrations of DMP-10 and DMP-14 were even more effective. The compound DMP-30, however, was found to be more effective in reducing loss of drying on aging than any other additive tested; therefore, further work was concentrated on this material.
Vol. 42, No. 3
One defect of DMP-30 is that in regular varnish formulations and in cases where there is a tendency for livering to occur, this tendency is accentuated by its addition. On the other hand, print,ing ink formulations based on transparent varnishes do not show this tendency in any case when DMP-30 is added. I t should be emphasized that DRIP-30 is most effective when used in amounts of 1 to 2% of the varnish. This corresponds at 0.3% cobalt to roughly 1 molecule of DMP-30 for each cobalt. Too much DMP-30 is just as ineffective as too little. M E c H A N I s i I OF DXP-30 ACTIVITY. Two approaches Tvere taken to investigate the manner in which the DMP-30 operates in preventing drying loss: first, through a study of solutions of cobalt and DMP-30 in hydrocarbon solvents and, secondly, through analysis for DMP-30 and cobalt' in the vehicle portion of a tartraxine yelloiv lake ink as it aged. Spectrophotometric analyses of solutions of cobalt in pentadecane and in cyclohexane furnished good evidence that in these solvents in the absence of a pigment, DMP-30 added as a free
100
1
/
/
- A-0.1551%
~
COBALT
/
~
,
~
1
~
IN PENTADECANE
8-0.0973%
90
AGE
Figure 7.
IN
-C-0.0223%
DAYS
Addition of DMP-30 to Aged Hydrate Lake Inks DMP-30
In some of the aging tests made with this additive, cobalt linoleate was used as a drier, but in the majority of cases Hexagon 6% cobalt drier (ildvance Solvents & Chemical Corporation) was used; no difference in the behavior of the DMP-30 with these driers was encountered. The alumina hydrate lake inks were made up with OK0 8-70 vehicle ( Archer-Daniels-Midland Company), acid number 2.9, so that the livering tendency would be minimized; pigment loading was 50% by weight,. During the aging period, 30 grams of each ink with a wax paper covering Kere stored in 1-ounce tin cans. The results from Figure 2 and Figure 5 indicate that the drying times of varnish, and even of printing inks made with a tartrazine yellow lake pigment, mere increased by the addition of DMP-30, but the drying loss of the inks on aging was greatly reduced. Therefore, the beneficial results of using DMP-30 seem to arise from its influence in preventing the removal of cobalt from solution in the vehicle. Preferent,ial adsorption of DMP-30 over cobalt was regarded at first as a possible mechanism. When DMP-30 was added to inks which showed no drier loss on aging, the drying time was increased but remained constant throughout the aging period. When DMP-30 was added to ink which had already been aged without the additive, the drying time was immediately reduced; these impressive results are illustrated in Figure 7. Drying tests were started 10 minutes after the DMP-30 was milled into the inks after portions were aged for various periods of time. Drying times were reduced to or below the init,ial value, but the recoveries were not permanent with the concentration of 0.7% DhlP-30 used here. Experiments to learn the effect of adsorbing DMP-30 on lake pigments before the inks were made up gave promising results so that more work along these lines is warranted.. Lake pigments agglomerate, however, if the DMP-30 is added directly from water solution. No doubt better results would be obtained if the addition were made during pigment manufacture. Additional studies with printing inks pigmented with peacock blue, Persian orange, and other yellow lakes gave results similar to those obtained with the tartrazine yellow lake ink. Thus, t'he general usefulness of DMP-30 in preventing drying loss in inks cont.aining alumina hydrate lakes was demonstrated.
350 400
4 5 0 500 550 600
650 7 0 0
W A V E L E N G T H IN M I L L I M I C R O N S
A-00057;
Co
8-00186 Go G - 0 0 1 8 6 % Co t O 1 2 4 7 % D \ I P - 3 0 ( 1 N l T I A L ) 3-00186% C o + 0 1 2 4 7 % DUD 3 2 ( 9 D A Y S ) E 4 0 1 8 6 % Co t CUMENE HYDROPEROXIDE
5
WAVELENGTH I N M I L L I M I C R O N S
Figure 8. Comparison of Characteristic Curves of Various Cobalt Solutions in Pentadecane (abooe) and Cyclohexane (below)
,
1
,
INDUSTRIAL AND ENGINEERING CHEMISTRY
March 1950
495
acidic, so it was recognized that they would compete with the cobalt drier for the basic DMP-30. Nevertheless, in view of the TABLE 11. COBALT ABSORPTION FROM PENTEDECANE SOLUTION findings in hydrocarbon solvents, it was surprising to learn that Pigment
Cobalt Remaining in Solution after 48 Hours, % 0.824 0.015 0,212 0.254 0.257 0.247 0.237 0.010
0.156
all of the DMP-30 was taken up by the pigment just after addition. Even more surprising was the fact that the cobalt adsorption was not reduced b the presence of the DMP-30. Of course, during the a ing perioi the drying time did not increase appreciably. Signifcant data are presented in Table 111. It is concluded, therefore, that DMP-30 prevents drying loss on aging simp1 by adsorption on the igment. The suggestion is made that d e reduction of the aci& atmosphere created by the pigment provides a more conducive atmosphere for the drying phenomenon to take place. Perhaps, then, the small amount of cobalt left in solution is effective in catalyzing drying just as in an unpigmented varnish. Certainly it is well known that acidic pigments inhibit drying so that far more cobalt is required in inks than in unpigmented varnishes. Furthermore, the work of Farmer ( I ) indicates that mineral acids decompose the hydrop d e formed first during drying to yield a saturated triol. his reaction would prevent the hydroperoxide from taking part in olymerizations and further oxidations conducive to drying. ft would also be of considerable importance to know what features of the structure of DMP-30 make it active and so much better than the other amines investigated. In an attempt t o clarify this picture the hydroxy group of DMP-30 was replaced by a methox grou and the new compound, 2,4,6-tri(dimethylaminomethyfianisok, was found to have nearly the same activity as DMP-30 itself. Thus, the phenolic group is probably not involved in the mechanism by which DMP-30 operates.
amine coordinates with any cobalt which can be oxidized to the cobaltic form. Cobaltic complexes in which the cobalt possesses a coordination number of six are more stable than the corresponding cobaltous complexes. Characteristic curves of various concentrations of cobalt in pentadecane, as represented in Figure 8, above, show that two minima occurred, one a t 575 mp and one a t about 380 mp. As shown by curves E and F, the addition of either DMP-30 or of the oxidizing agent, cumene hydroperoxide, eliminated the minimum a t 575 my but greatly intensified the 380 mp minimum. The permanence of the low wave length minimum upon the addition of oxidizing or complexing agent indicated that it is due to cobaltic cobalt while the higher wave length minimum is due to cobaltous cobalt. Apparently, in concentrated pentadecane solutions nf cobalt. the ratio of cobaltous to cobaltic cobalt was high but as the concentration of cobalt was diminished, the oxidizers present in TABLE 111. DMP-30 AND COBALTADSORPTION IN TARTRAZINE YELLOW LAKEINK the pentadccane solvent were sufficient Amt. to oxidize practically all of the cobalt Added Blank Ink Ink + DMP-30 to the cobaltic state. However, as shown Vehicle TDay 3Days 5Days 2 Yr. ‘1 Day 3Days 5Days 2 Yr. 2 Nn as DMP-30 0.24 0.047 0.065 0,015 0.027 0.025 0.016 in Figure 8, below, practically all of the % Cobalt, approx. 0.14 0.060a 0.005 0.’005 . . . 0.054n 0.0035 0.004 ,,. cobalt remained in the cobaltous state at pigment % Cobalt ... ... ... 0.130 . . . ... .. . 0,133 . . very dilute solutions of cobalt in cycbhexane. a The vehicle was separated from the pigment by adding petroleum ether and immediately centrifuging. In these cases a small amount of the pigment remained in the extract. DMP-30 did not remove the high wavelength minimum when it was added t o a cobalt solution in cyclohexane in the absence of an oxidizer as in the case of The only remaining important feature of its structure is the cobalt solutions in pentadecane. Over a period of time after large flat molecule with three widely separated basic groups. DMP-30 had been added to cyclohexane solutions of cobalt, Perhaps this molecule is held flat against an acidic surface and however, the cobalt was eventually oxidized,. probably by oxythus has high covering ability. The DMP’s with only one basic gen from the atmosphere, and the cobaltic state was then group ortho to the phenol are much less effective in preventing stabilized by the complexing agent. The addition of cumene drying loss on aging. hydroperoxide to cobalt solutions in either cyclohexane or pentedecane produced the same characteristic curves as those produced by DMP-30. ACKNOWLEDGMENT Adsorption studies were also made using slurries of various igments with pentadecane solutions of cobalt ethylhexoate. The authors are pleased to acknowledge the very helpful dis$en per cent slurries of pigment in solutions of approximately cussions with W. C. Walker. V. B. Fish was particularly helpful 0.3% cobalt were analyzed before and after agitation for various periods of time. The amount of cobalt remaining in solution in designing and conducting some of the analyses and in preafter 48 hours is indicated in Table 11. These analyses were paring the n-hexyl ester of hemin and the methylated derivative made by a new method for cobalt to be published elsewhere. of DMP-30. This method is based on an extraction with concentrated hydrochloric acid to yield solutions having sensitive transmittance curves without the addition of any coupling agent. The large LITERATURE CITED effect of DMP-30 in preventing adsorption of cobalt is evident (1) Farmer, E. H., Bloomfield, G. F., Sundralingam, A,, and Sutton. in these results. There is also evidence that 2% DMP-30 was the most effective concentration. D. A., Trans. Faradau SOC.,38, 348-56 (1942). Inks were also made up with the particular sulfated and (2) Gardner, H. A., and Sward, G. G., “Physical and Chemical phosphated alumina hydrates for which the adsorption results Examination of Paints, Varnishes, Lacquers and Colors,” are tabulated in Table TI. (These results do not mean that the 10th ed., p. 152, Figure 214, Bethesda, Md., Inst. of Paint and sulfated product is always inferior as to drying loss; indeed, with Varnish Research, Henry A. Gardner Laboratory, 1946. some other samples it has been found that results are the reverse (3) Nicholson, D. G., IMD. ENG.CHEM.,31, 1300 (1939); 34, 1175 of those given in Table 11.) The ink containing the sulfated (1942); J. Am. Chem. Soc., 64, 2820 (1942). hydrate caused much more rapid and serious drying loss on aging (4) Panimon, Frieda, Merwitt, M. K., and Gerard, R. W., J . CeZZular than did the phosphated hydrate. There is evidence, therefore, that a drier adsorption study from pentadecane solution could Comp. Phvsiol., 17, 17-29 (1941). be used as a rapid method for predicting the tendency of a pig(5) Robinson, M. E., Biochem. J.,18, 255-64 (1924). ment to cause drier loss in printing inks or paints. (6) Wheeler, G. K., IND. ENG.CHEM.,39, 1115 (1947). These results obtained from solutions in hydrocarbon solvents (7) Worthington, E. A., and Nicholson, D. G., Paint, Oil, Chem. appeared to support the contention that DMP-30 prevented Rev., 112, 20,40-6(1949). drying loss by complexing with the cobalt in the +3 state, and (8) Zettlemoyer, A. C.,Lower, G. W., and Gamble, E., Ibid., 41, that thereby the cobalt was not taken up by the pigment. It 1501 (1949). remained, therefore, to demonstrate that the DMP-30 remained in the vehicle portion of a printing ink during aging. Therefore semimicroanalyses for nitrogen were conducted on inks with and RECEIVED August 27, 1949. Presented before the Division of Paint, Varwithout DMP-30 added. nish, and Plasticschemistry at the 116th Meetingof the AMERICAN CREMICAL Alumina hydrate pigments which cause loss of drying are SOCIETY, Atlantic City, N. J.
.
