1562
INDUSTRIAL AND ENGINEERING CHEMISTRY
caused permanent damage to the catalyst surface, resulting in the very short life, apparent in Figure 8, during the second reaction cycle. It is to be noted, however, that catalyst activity was a t least temporarily restored to its original level upon completion of the reactivation, only the life having been impaired by the excessive temperatures to which it was exposed. The above constitutes only one set of data, and is, therefore, an insufficient basis from which to draw accurate conclusions, particularly concerning so complex a problem as catalyst regeneration. However, further investigation should very shortly complete the data on this phase of the process, and will be presented in a later paper concerning the kinetics and mechanism of the reaction. The presence of a slow stream of nitrogen v a s essential to the successful production of a \\bite grade of diphenylamine. In the absence of nitrogen, a low yield of a very dark product was obtained, indicating considerable oxidation and decomposition had occurred.
Vol. 42, No. 8
version increases 7vit.h decreasing space velocity, BS might be expect'ed. Based on only one set of data, it seems that the catalyst life is approximately 10 hours. Assuming that regenerat,ion is possible with close control of the process temperature, by limiting either the amount or concentration of air in t'he regeneration gas mixture, t'his life should not be too short for industrial purposes. 110 generation of t'his type of catalyst is accomplished in virtually every other type of installation in which it is used, and there is no apparent, reason why regeneration should prove to be impossible in this process. If it is possible, then with several chambers, one in production while the others are on the regeneration cycle, the process should offer many advantages over the present liquid phase batch process, depending upon the scale of production. ACKNOWLEDGMENT
The authors wish t o express their appreciation for the information and advice furnished by F.'. M. Stowe of the Aluminum Company of America, and to I,. h.Burrows of E. I. du Pont de Keinours 6 Company, Inc.
RESULTS AND CONCLUSIONS
LITERATURE CITED
Activated alumina will catalyze the vapor phase condensation of aniline to diphenylamine, resulting in a rate of reaction which permits the process t o be of commercial interest, and producing no side reactions in detectable quantities. I n operation, the process is such that a partial rondensatiori system, involving continuous removal of the diphenylamine as a liquid and recycle of the aniline-nitrogen vapor, should be feasible. This should result in virtually complete reaction of the aniline fed. The diphenylamine produced has a melting point of 51' to 53" C., comparing favorably x i t h the literature value for the pure substance, 52.9" C. Kitrogen carrier gas is used both to m e e p the reactant and products along the chamber and also to provide the inert atmosphere necessary to prevent oxidation and decomposition of the materials involved. Couversion of the aniline to diphenylamine increases with increasing temperature at constant space velocity, first becoming appreciable a t temperatures around 400 C. Since decomposition of both aniline and diphenylamine begins a t a p p r o ~ i m a t e l y 4 7 0 C., ~ this sets an upper limit on the process temperature; 460' C. appears to be the most satisfactory point of operation. Con-
Acken, M. F., U. S. I'aterit 2,082,815 (June 5, 1937). I b i d . , 2,120,969 (June 21, 1938). D o b r a t z , C . J., IND. ENG.CREW,33, 759 (1941). Flurscheim, B. J . , U. EL P a t e n t 1,212,928 ( J a n . 16, 1917). (5) Frei, J., Ibid., 1,840,576 ( J a n . 12, 1932). (6) Glasstone, S., "Textbook of Physical C h e m i s t r y , " p. 1092, S e w York, D. Van N o s t r a n d Publishing Co., 1940. (7) H o u g e n , 0. A,, a n d Watson, X. >I., "Chemical Process Principles," P a r t I, p. 70, New York, J o h n Wilcy & Sons. I n c . , 1943. ( 8 ) H o u g e n , 0. A , a n d TTatson, K. M., "Industrial Chemical Calculations," p. 113, Xew York, J o h n Wiley & Sons, Inc., 1936. (9) Loeb, 1,. B., "The K i n e t i c T h e o r y of Gases," 2nd rd., chap. 111, New Tork, McCraw-Hill Book U o . , 1934. (10) Pauling, L., "The N a t u r e of t h e Chemical Ibnd,'. p. 50. Ithaca. N. Y . ,Cornell C n i v e r s i t y Press, 1540, (11) T e s t e r , A. B., Burrows, L. A , , and Johnson K. R.. 1'. S. I'atcnt 2,447,044 (Aug. 17, 1948).
ANTIFOU
(1) (2) (3) (4)
KV;CF:ITLD October 6. I
G PAIN
Tall Oil and Rosin Derivatives in Toxic Paint Vehicles ALLEN L. ALEXANDER, R. L. BENE1\IELLS', .AND S. K. (IRECELTUS' "auk Reseurrh Laboratory, Wushington 2.5, D . C.
As a result of
the huge quantities of rosin consumed in the wartime production of antifouling paints, studies were inaugurated with a Fiew of determining the role of rosin substitutes for use in soluble-matrix antifouling paint. The advent of tall oil in commercial quantities made it ail interesting prospect for this study. In addition tall oil esters of glycerol and pentaerythritol were prepared and studied along with abietic acid and hydrogenated methyl abietate as rosin diluents. The esters appear to affect antifouling efficiency and physical durability adversely in direct ratio to the extent to which they are substituted. Abietic acid and hydrogenated methyl abietate improve perceptibly the phj-sical qualities of the film. Tall oil may be substituted for rosin up to 50% writhout affecting the performance of the paint.
1
Present address, Sinclair and Valentine Company, Ridgevmy, Pa. Prwent address, American Cyanamid Company. Stamford, Conn.
RCVIOUS papers (1-3) discussed the effects of various pigment properties on the quality of antifouling paints. The present study reveals information on the properties of matrix constituents as they affect the performance characteristics of the paint. Several theories relating to the mechanism by vhirh successful antifouling coatings function have been proposed. Among the more popular theories is that of Ketchum, Ferry, and Burns ( 4 ) relating t o matrix solubility. These authors have demonstrated that in the design of soluble-matrix paints in vhic.11 the rate of toxic release is controlled by matrix solubility rosin can play an important role since it possesses an optimum solubility in sea water. Objectionable properties of rosin such as brittleness and poor water resistance require considerable modification before paints of practical durability may be prepared employing rosin as a major matrix ingredient. Since rosin is used extensively as the principal constituent of the matrices of both hot and cold plastic paints, the advent of tall oil in sufficient commercial quantities for such application appeared most interesting as a possible substitute or diluent for rosin in the formulation of soluble-matrix coatings.
August 1950
INDUSTRIAL AND ENGINEERING CHEMISTRY
1563
A CUeO 0 CU PIGMENT
LIL)
ROSIN CONTENT-PER
70
50
60 ROSIN CONTENT-PER
CENT
CENT
Figure 1. Fouling Resistance of RosinPentaerythritol-Tall Oil Ester Blend
Figure 2. Fouling Resistance of RosinGlycerol-Tall Oil Blend
hlthough the performance of rosin has been favorable when compared to most diluents and substitutes previously studied, the search for additional materials likely t o improve the performance of the paint was continued. Tall oil, being of similar origin and in an advantageous economical position, appeared t o warrant study in typical antifouling formulations. It was recognized that this product of natural origin might be lacking in uniform qualities which may be so much more closely controlled in synthetic materials. With this in mind and with a view of broadening the scope of the study, it was considered desirable t o include some reh e d and processed derivatives of rosin-namely, hydrogenated methyl abietate (a neutral ester) and abietic acid (a purified rosin acid), These materials along with the glycerol and pentaerythrito1 esters of tall oil formed the major constituents for all formulations.
the amount of coal tar naphtha necessary for appropriate grinding viscosities. This usually resulted in a total solids content (pigmented) of about 71%. The Pliolite was cold cut into the other harf of the solvent and added to the rosin solution after cooling, forming 4% of the vehicle solids. Each vehicle was pigmented with cuprous oxide and a proprietary copper pigment containing approximately 85% (by weight) metallic copper and 15% cuprous oxide. Diatomaceous silica comprised 15% of the total pigment in each instance. Grinding was accomplished on a labora-
TABLE I. ROSINAND PENTAERYTHRITOL-TALL OIL ESTER BLEND Vehicle
Composition, % _______
PREPARATION OF PAINTS
The esters were prepared by heating glycerol and pentaerythritol with tall oil dissolved in toluol in a three-necked flask a t 200' C. under agitation. When the acid value of the product had decreased sufficiently to indicate the complete reaction of the polyhydric alcohol, carbon dioxide was introduced below the surface of the solution to retard further oxidation. Heating was continued a t 210' C. until the acid value of the product dropped from an average original value of 172 to below 10. The amount of glycerol and pentaerythritol in each case was molecularly equivalent to the original acid value of the tall oil, plus 10% to allow for heating losses and impurities. An acid value below 10 is considered necessary to ensure against excessive reactivity with some pigments. The pentaerythritol ester required considerably longer time for complete esterification and possessed a much heavier final viscosity. These esters along with the other ingredients were blended into modifications of specification 52P61M, the vehicle formula of which follows:
Rosin 80 72 64
48 32 0
Pentaerythritoltall oil ester 16 24 32 48 64 96
Performance Condition a t 10 Months Months above Fouling Physical Fouling Physical resistance, condition, resistance condition % % Cuprous Oxide 10 10 80 80 7 10 55 85 6 10 35 88 0 10 0 85 0 10 0 80 0 2 0 30 Copper Pigment 8 10 6 10 2 10 1 10 0 2 0 2
64 32 4
This vehicle is normally reduced with coal tar naphtha and pigmented a t 25% pigment-volume with & mixture of 85% cuprous oxide and 15% (by weight) diatomaceous silica. For the purpose of these experiments the ratio of rosin t o each diluent varied from 80% maximum to 0%. The ingredients were blended by heating the rosin with each diluent in the proper ratio until they were completely fused (about 150' C.) and then thinning with half
65 0 0 0
0
85 88 80 80 50 30
TABLE11. ROSINAND GLYCERINE-TALL OIL ESTERBLEND Vehicle Composition, %
ClyoerdRosin
Monthsabove 80%
tall oil ester
Fouling resistance
16
10 10
% W. W. rosin Methyl abietate Pliolite 9-1
75
80 72 64 48 32 0 80
72 64
48 32 0
24 32 48 64 96
16
24 32 48 64 96
9
10 0 0
Physical condition
Cuprous Oxide 10 10 10
90 80 75
80 92
10
0 0
0
85 70 70
72 75 0 0 0 0
72 83 85 85 85 75 70
6 2
Copper Pigment 9 7 9 1
1 0 0
Condition a t 10 Months Fouling Physical resis%ance, condition, % %
10
10 10
4
2
__
9.i
Vol. 42, &,
I N D U S T R I A L A N D E N G I N E E R f R G eliSEMISTWY
1564
TABLE 111. ROSIS-TALLOIL BLEND Vehicle Co1nPosition, % Rosin Tall oil
Performance Condition a t 10 Months
Months above 80%
resistance, resistance
%
condition
condition,
tory three-roll mill. Panels were prepared for expdhwe by the application of four coats to plywood. The finished panels were immersed in Riscayne Bay a t Miami Beach, Fla., for a total period of 10 months, and their condition was noted a t monthly intervals.
%
PAINT PERFORMANCE
Cuprous Oxide
Coilper Pigment 80
72
64 48
32 0
TABLE IT'. ROSIN-ABIETIC A4C10 BLEND Performance
Vehicle Composition, 7* Abietic Rosin acid
8
.. . _ _ ~ P bIonths
Months above 80% Fouling Physical iesistance condition
resistance, %
physical condition, %
Cuprous Oxide 80 72
64
48 32 0
hlost methods for the accurate evaluation of pei formance of exposure panels leave something to be desired. The method used earlier ( I - S ) , as developed by the Woods Hole Oceanographic Institution, appears t o be one of the more satisfactory so far presented, At each inspection, the panels are given a critical examination to determine the exact number of fouling organisrns that have attached during the exposure to date. Notes are made describing the variety and types of organisms present. Additional notations are included relating to the physical condition of the paint systems. After studied consideration of each of these factors, a numerical estimation of the fouling resistance and physical stability of the paint is given in per cent; an unaffected panel rates l O O q and one that has fouled completely is rated 0%. Similar figures are used to denote the physical condition of the paint film. In making these observations, conditions attributable to edge effects are discounted and the recorded figures indicate the percentage area of each panel free of fouling attack and physical degradation, The data of Tables I to V were compiled from the monthly reports which present fouling resistance for each eombination by months.
Copper Pigment
80
16
10 10
10
32 48 64 96
10 10 10 10
10
24
72
64 48
32 0
DISCUSSION
91 84 86
7
87
10
88 90
10
10
TABLE I-. ROSIN-HYDROGENATED METHYL
82
ABIET.4TE
BLEND
PPI - ...fnriiiance ~.. . ~~
Vehicle Composition, % H-Methyl Rosin abietate
Condition a t 10 Months Fouling Physical resistance, condition,
Months above 80% Fouling Physical resistance condition
%
70
Cuprous Oxide
Although the principal objectiveof this studywas matrivproperties, some opportunity was presented to observe the relative efficacies of two copper pigmenk From the data it is obvious immediately that any characteristic imposed on the paint att'ributable to the pigment,s is relatively inconsequential when compared to changes in the matrix composition. The curves of Figures 1 to 5 show the efficiency of each pigment at the end of 10 months. In most instances, inferior performance is noted for the copper pigment where the rosin content is higher. Ilowever, the evidence in favor of cuprous oxide is not, overwhelming, though a distinct advantage does exist in favor of this standard pigment. In earlier experiments ( 2 ) the advantage of cuprous oxide a t high pigment-volume over the copper pigment \\-as demonstrated where application is intended for steel. The effect of matrix composition on performance is quite
Copper Pigment
60 80
TO
60
50
40
30
20
10
0
ROSIN CONTENT-PERCENT
Y
Figure 4.
Fouling Resistance of Rosin-..ibietic Acid Blend
Figure 5.
Fouling Resistance of Rosin-Hydrogenated Methyl Abietate Blend
+ 0
I
I
I
I
I
I
I
0 ROSIN CONTENT-PERCEW1
August 1950
INDUSTRIAL AND ENGINEERING CHEMISTRY
marked, as is adequately demonstrated by the data of Tables I and 11. It must be concluded that tall oil esters have no place in the formulation of soluble-matrix paints, cven a t the lowest ester concentration (16%). Antifouling effectiveness is reduced somewhat below the standard with no compensating increase in the physical stability of the film. Formulations containing equal parts of rosin and tall oil ester result in films that possess an effective life of only 1 month and fail completely after 3 to 4 months. This failure is demonstrated further by the curves of Figures 1 and 2. On the theory of Ketchum and co-workers ( 4 ) t h a t matrix solubility accounts for the functioning of this type formulation, an explanation of the data would lie in the fact that the solubility of the matrix is gradually reduced through the addition of insoluble ester to a point where sufficient amounts of copper to prevent fouling are no longer available a t the paintwater interface. Aside from film solubility characteristics, a second factor probably contributes to the observed phenomena: Solutions of rosin produce grinding and wetting media which are relatively poor when compared with more highly regarded vehicles. Good pigment dispersion in rosin alone is difficult, and in such a medium the pigment particles may be conceived as being held in place in somewhat the same manner as bricks are held together with mortar. Thus, there are available comparatively large areas of pigment that may be exposed t o the solvent action of sea water. On the other hand, an esterified rosin, or in this case, esterified tall oil assumes the characteristics of a fairly good grinding medium in which the pigment particles are well covered by envelopes of the matrix. Thus, the matrix must be penetrated or dissolved by the sea water before any copper from the enclosed particles may pass into solution. This concept appears to be justified by the facts as demonstrated by poor performance of the films containing large amounts of ester. Although rosin and presumably tall oil to a similar degree are soluble in sea water, they are fairly stable against rapid deterioration in contact with sea water. Poor physical stability of film high in ester indicates that in the higher concentrations the esters are subject to deterioration, manifested by a rapid physical breakdown which is obvious immediately in the degradation of the film. This is more pronounced in the case of the pentaerythritol ester than for glycerol. I n the formulations in which rosin was diluted with abietic acid and hydrogenated methyl abietate and even with an unesterifiyd
1565
tall oil, performances approximately equal to rosin were obtained. This perhaps was not unexpected in view of structural similarities in each ingredient. The data on both physical properties and antifouling efficiency are somewhat more consistent with abietic acid and hydrogenated methyl abietate than for the tall oil blends which may be the result of their higher degrce of purification and increased uniformity from batch to batch. Tall oil is somewhat less pure and uniform than rosin although its solubility and wetting properties are quite similar. For an exposure period of 10 months it is obvious that hydrogenated methyl abietate and abietic acid do not alter appreciably the performance of a rosin matrix regardless of the ratio of rosin to diluent. With tall oil alone, inferior performance is indicated when its percentage exceeds 7091,. Below this figure paint prepared from tall oil rosin mixtures performed as efficiently as those containing normal amounts of rosin. CONCLUSIONS
The data indicate that tall oil may replace up to 50% of the rosin normally present in a soluble-matrix type antifouling paint without affecting seriously the antifouling efficiency or physical stability of the film. Similarly, hydrogenated methyl abietate and abietic acid may be substituted for rosin up to 1007, with a perceptible improvement in physical properties and equivalent performance as a fouling deterrent. Esters of tall oil, as illustrated by the glycerol and pentaerythritol derivatives, produce a marked adverse effect on soluble-matrix paints in direct proportion to the extent to which they are substituted. A copper pigment containing essentially 85y0 copper and 15% cuprous oxide does not quite equal cuprous oxide as an antifouling pigment in the matrices studied. LITERATURE CITED
Alexander, Allen L., Ballantine, J. B., and Yeiter, M. O., IND. ENG.CHEM.,41, 1737 (1949). (2) Alexander, Allen L., and Benemelis, R. L., Ibid., 39, 1028 (1947).
(1)
(3) Ibid., 41, 1532 (1949). (4) Ketchum, B. H., Ferry, J. D., and (1946).
Burns, A. E., Ibid., 38, 931
RECEIVED October 13, 1949. Presented before the Division of Paint, Varnish, and Plastics Chemistry a t the 116th Meeting of the AVERICAN CHEMICAL SOCIETY, Atlantic City, N. J.
N-Hvdroxvalkvl Amides of Lactic Acid J
J
J
PREPARATION AND PROPERTIES WILLIAM P. RATCHFORD Eastern Regional Research Laboratory, Philadelphia 18, Pa. Seven N-hydroxyalkyl lactamides were readily prepared in high yield by aminolysis of methyl lactate with amino alcohols. These lactamides are water-soluble compounds of low volatility; six liquid lactamides had viscosities ranging from 4000 to 26,000 centipoises at 20" C. They varied widely in hygroscopicity; one, N,N-bis(2-hydroxyethy1)lactamide was more hygroscopic than glycerol. Because they can be considered as polyhydric alcohols, they may be useful chemical intermediates, as well as hygroscopic agents.
A
LTHOUGH it has been reported that N-hydroxyalkyl amides of aliphtic (9, 15, 17), glycolic (19),and hydroxystearic acids (10,29) are of industrial interest as waxes (9, 10, WS), plasticizers (19, 18), emulsifiers ( I O , 15, bS), and as humectants and thickening agents (IS), apparently little attention has been directed to the N-hydroxyalkyl lactamides (91,95). I n general, these lactamides can be prepared easily in high yield by the aminolysis of methyl lactate with amino alcohols; in the work reported here seven lactamides were prepared in this way (Table I). The starting materials are commercially avail-
