Influence of Phenolic Resins on Linseed Oil Films V. H. TURKINGTON, R. C. SHUEY, AND L. SHECHTER Bakelite Corporation, Bloomfield, N. J.
T
I n a previous paper (IO)the authors reported their findings HE study of linseed oil as a film-forming material is alon the film properties of a series of varnishes made from a most as old as the varnishindustryitself. Its behavior pure phenol-aldehyde resin (Bakelite resin BR-254) and a under a multitude of conditions, both alone and in commixture of linseed and China wood oils in varying proporbination with pigments, driers, resins, other oils, and many tions. The present paper is based on a continuation of this other ingredients. has been studied by hundreds of investiwork but is limited to a gstors. This accumumore detailed study of lated knowledge regardsome of the more iming linseed oil has conportant chemical and tinually added to its physical effects produced usefulness; although in Data are presented showing the effect when linseed oil alone recent years it has been of the phenol-aldehyde resin, Bakelite is cooked with varying displaced to a considerresin BR-254,on the course of the heat proportions of the same able extent by China phenolic resin. wood, perilla, and other treatment of linseed oil and on the propThe term “pure drying oils in varnish erties of the film produced therefrom. phenolic resin” covers a making, it still retains Viscosity, density, and refractive index group of materials of the most important changes are accelerated by incorporating widely divergent properposition in such fields as varying proportions of this compound ties (@, thus preventing house paints, linoleum, broad generalization and and oil cloth, as well as into linseed varnishes. The extent of necessitating that indiin many types of baking these changes is greater than can be vidual resins be given as finishes. ascribed to the additive effect of the indicareful a study as the Even though, in comvidual components. individuals of the group parison with China wood The distensibility of linseed oil films is “vegetable oil” are given, oil, linseed oil has certain at least until such time weaknesses, of which beneficially influenced by the presence a s chemical s t r u c t u r e slowdrying and relatively of this resin. For example: (a) The can be defined more acpoor water resistance are elongation per unit of load is increased wrately. perhaps the most outthroughout the investigated life of the The investigation of standing, nevertheless film a t concentrations of this resin up to the chemical composithe authors have felt that tion and behavior of the its good properties, such something over 10 per cent. (b)The elonmore generally used varas ease of handling in a gation a t maximum stress and rupture nish oils has resulted wide range of heat treatcan be enhanced by incorporation of the in the conclusion that ments, good elasticity, proper amount of this resin, in achardening and film forand retention of fleximation in varnishes are cordance with the type of service desired. bility and toughness on due principally t o aging entitle it to further (c) The comparative elongation with simultaneous oxidation investigation. With the aging is improved as aging progresses, in and polymerization, both advent of new synthetic that although elongation of a linseed oil these processes taking resins which are capable film first increases and then decreases, place a t the cherriically of combining with linreactive double bonds. this resin accelerates the rate of increase seed oil to form entirely I n these cases the hardnew chemical products, and retards the rate of decrease ; the final ness and rigidity of the it is reasonable to exresult is a marked improvement in the oil film appear to be pect that these products distensible life of the coating. roughly proportional to should behave differently A progressive increase in alkali resistthe number of double from linseed oil itself bonds capable of enterance properties and boiling-water duraand require some reviing into the polymerizasion of ideas concerning bility of films is induced with increasing tion reaction. the inherent usefulness phenolic resin content. The study of the polyof linseed oil as a raw merization of both natumaterial.
-
984
SEPTEMBER, 1938
INDUSTRIAL AND ENGINEERING CHEMISTRY
ral and synthetic substances has resulted in several generally accepted concepts, notably that polymerization which produces but a simple increase in chain length is accompanied by retention of fusibility and solubility, whereas polymerization through the formation of multiple cross linkages tends to produce insolubility and infusibility. Greater flexibility and extensibility under stress tend to be inherent properties of the first class, whereas cross linkages tend to produce films possessing greater mechanical hardness, strength, and chemical resistance. However, mere existence of cross linkages does not by any means ensure the property of chemical resistance. Obviously the presence or absence of reactive groups in the polymer will in many instances be the deciding factor, for dissolution may result from chemical attack a t these reactive points. Thus, an abundance of cross linkages can hardly be considered a safe criterion of chemical inactivity and resistance to moisture. On the other hand, the straight paraffin hydrocarbons have a fairly good record for moisture resistance and chemical inactivity. This is presumably because of the absence of reactive groups. However, the utility of this substance as a protective film is limited because of poor mechanical properties, resulting probably from the absence of cross linkages. Therefore, the two factors must be viewed simultaneously before any definite conclusions as to physical and chemical properties can be drawn. This study of the film properties of linseed oil films is added to the already voluminous literature on the subject, principally because it is felt that certain data contribute towards a fuller understanding of film behavior. The choice of phenolic resin BR-254 as the modifying agent was made because of the repeated observation in practice that this hard resin, contrary to the general rule, was capable of producing an increase in the strength of the linseed oil film without a corresponding decrease in the flexible life.
Experimental Procedure and Equipment The varnishes studied were prepared by open cooking in a heavy copper pot, the bottom of which had a thickness of about 5 mm. A vessel of this type was employed because it closely approximates the heat transfer conditions commonly present in varnish plant kettle processes. Heat was supplied by a gas hot plate operated by means of a bimetallic thermocouple potentiometer control, which was sufficiently sensitive to maintain the desired temperature within limits of * I" C. TG ensure an equal distribution of heat throughout the batch, continuous agitation was produced by rapidly rotating a stirrer equipped with a smooth metallic disk. This was driven by a small laboratory motor. As an added check on the automatic temperature control a 3-inch immersion thermometer was placed in the kettle. A unit batch of 7000 grams was employed, for this permitted withdrawing samples of sufficient amount to be adequate for subsequelit measurements. These samples (approximately one pint or one-half liter) were rapidly cooled by immediately immersing the containers in cold water. As the heating progressed in the kettle, the time and temperature were frequently recorded. Since a definite amount of change was produced in the oil when it was warmed from room temperature to 560" F. (293" C.) it was thought necessary, for the purpose of consistent graphical representation, to devise some method whereby the extent of this alteration could be estimated. After this evaluation is once made, it is necessary to convert over into a time a t 560" F. which will give an alteration identical with that produced in the warming-up period. As a basis for evaluating the amount of heat treatment given the oil in any period of time a t any temperature, a
985
graph of the observed gelation times of linseed oil a t various temperatures was constructed. By a process of summation the extent of heat effect on warming to temperature can be estimated ; and if the time required to produce a gel a t 560' F.
AF===iIA
Constant-Eriverafure contra/ fir
I
_ -
FIGURE 1
is known, it is a simple matter to convert the estimated heat effect in terms of gelation extent to a time a t 560" F. which will produce an identical change. These are the values shown as time a t 560" F. and not the total time on the fire, which was considerably longer (generally about 45 minutes). The time required for complete gelation is halved by an increase of approximately 21 O C. in temperature or, conversely. doubled by a decrease of 21 " C., so it is only as the temperature approaches 560°F. (293°C.) that the heat treatment producible during warm-up becomes appreciable. A rise to a temperature of 560" F. in 55 minutes would thus be equivalent to 9 minutes a t 560" F. and would be so recorded. For the 450 " F. cooks conducted a t lower temperatures-namely, (232" C.) and 500" F. (260' C.), the correction was so small when compared to total cooking time that it could be entirely neglected. Here zero time was recorded when the batch reached the desired temperature. During the progress of the cook the viscosity a t kettle temperature was periodically determined by a Brookfield viscometer. This instrument consists of a rotating disk driven by a constant-speed motor (Telechron clock type), the power being transmitted through a spring in such a manner that the torque produced by the viscosity of the liquid can be read on a dial graduated to read directly in centipoises. This instrument was checked against the tube viscometer generally used in the laboratory and satisfactory agreement was found. The samples withdrawn were used for determining viscosity a t 25" C., density a t 25O, refractive index a t 25", and iodine number (Hams). The iodine numbers were determined only on the oil, as the presence of resin interferes with the accuracy of this determination and it was felt that either refractive index or density would be equally valuable criteria of the progress of the bodying of the oil. Figure 1 depicts the method used in the laboratory for maintaining both viscometer and refractometer at a definite temperature. Point 11 indicates a 5-pound jar, the bottom of which was
INDUSTRIAL AND ENGINEERING CHEMISTRY
986
VOL. 30, NO. 9
.q$000
minures
at-560~
FIGURE 2
possible t o operate these instruments at temperatures in excess of 100" c.
FIGURE 4
removed. Into the neck of the jar was cemented a large fourhole rubber stopper. Through one aperture was inserted an inlet, 1, for water; through a second, an outlet for the viscometer, 7; through a third, an outlet for circulating water, 2; and through the last, an overflow tube for excess water, 6. Water circulates through the tube 2 and refractometer 3, and on arriving at the second bottle, 12, is lifted by a steady stream of comT e e d air, 4, through tube 5 and thereby returned to the jar. nlet 1 serves only t o fill the container, and upon so doing is immediately cut off. The temperature of the bath is adjusted and maintained at 25' C. * 0.5' by thermoregulator 8, relay 10, and heating unit 9. The designated arrangement is highly recommended because of its great flexibility. By choosing suitable bath liquids it is
As a check against the comparability of the various cooks, 50-gram portions, identical in composition with the larger batches, were made in 125-cc. test tubes. For this correlation a 3-liter oil bath was controlled near 560°F. by a similar regulator, and a 50-gram sample of linseed oil containing a thermometer was immersed in it; care was taken that the level of the oil in the tube was well below that of the oil in the bath. It was found that with the bath a t 570" F. (299" C.) the tube would reach 560" F. (293" C.) in 10.75 minutes and rise no higher. Therefore the regulator was set for 570 F., and when that temperature was reached, the tubes containing the 50-gram cooks were inserted a t 10-minute intervals by stop watch. By employing such an interval, ample time was permitted for withdrawing samples for refractive index readings. All cooks were thus made practically simultaneously and carried through to gelation, as shown by their final inability to drop from the stirring rod when withdrawn from the oil. The changes in refractive index of these cooks are shown in Figure 5, along with the refractive indices of the equivalent kettle cooks. The same graph shows the gelation times of these cooks. Refractive indices a t gelation could not be determined, so the last or g point does not give a valid refractive index value but simply gelation time. The cooks compared in both these series consisted of straight alkali-refined linseed oil, 95 per cent linseed oil plus 5 per cent Bakelite resin BR-254, 90 per cent linseed plus 10 per cent BR-254, 80 per cent linseed plus 20 per cent BR254, and 60 per cent linseed plus 40 per cent BR-254. At some stage in the cook the linseed oil can be considered representative of the bodied oils used in such industries as fabric coating, patent leather finishing, printing ink manufacture, or the painting of wood. The graphical data fur-
INDUSTRIAL AND ENGINEERING CHEMISTRY
SEPTEMBER, 1938
987
#x)
.9a
denslq detei-mned of 25'C. t/mp coffected for WarmyperM
-1 so
i mo
/50
ZDL,
I 250
300
30
minufes FIGURE6
m m h FIGURE5 nished show the modifying influence in properties produced on addition of resin BR-254 to linseed oil cooks commonly employed in the fields mentioned. The highest concentration of resin (40 per cent) because of greater hardness, quick drying, resist,ance to chemical action, and lesser elongation would perhaps find application where rapid production of films is necessary on rigid surfaces subject to rigorous chemical attack.
Graphical Data Figure 2 shows the viscosities a t 25' C. of the four cooks a t various stages of sampling. Figure 3 shows viscosities taken a t the cooking temperature 560 O F. (293 " C.). The method of determining both hot and cold viscosities lends itself to plant practice in that the viscosity of the varnish when cold can be roughly estimated from measurements made on the hot oils. Figure 4 shows hot viscosities for three different cooksnamely, a linseed oil cook a t 500" F. (260' C.), a linseed oil cook a t 450' F. (232' C.), and a 75-gallon linseed oil-BR-254 resin cook a t 450" F. (15 per cent resin). Figure 5 shows the changes in refractive index of the various varnishes with cooking time. Both the kettle and the tube cooks are shown. Almost perfect agreement between the two methods is exhibited by the straight oil; on the other hand, in practically every case of difference in the others, the tube values are higher than the kettle values. At present no conclusive explanation can be forwarded as to the reason for this difference. Refractive index increase perhaps may be accepted as an indication of polymerization; however, the fact should be pointed out that a refractive index rise may well result from other sources, such as a shift in position of the double bonds to a conjugated system. Although most oil-resin combinations show an increase in refractive index with cooking, China wood oil, the most active of all, displays a decrease in this property with heating. In the linseed oil experiments, a normal increase of about 0.0020 unit per hour a t 560" F. was found; with the cooks containing resin the change per
FIGURE7 hour was 0.0020, 0.0038, 0.0052, and 0.0064 a t 5, 10, 20, and 40 per cent resin concentration, respectively. Figure 6 shows that the changes due to the presence of resin are still more marked. The addition of the resin has naturally added to the density of the mixture. However, when the various compositions are cooked, the slope of the density-time curve increases with increase in resin content. This increase in slope cannot be ascribed to the density change
988
INDUSTRIAL AND ENGINEERING CHEMISTRY
of the resin itself, for on heating resin BR-254 alone a t 560" F. for 5.5 hours the density remained practically constant. An original value of 1.201 was found. The final value was 1.208. The explanation of this phenomenon may perhaps come from either of two viewpoints. The resin may alter the course of the normal reaction by catalyzing polymerization and proportionately decreasing oxidation, or it may react with the oil and form a denser complex of a type different from that of straight-oil polymerization. Which viewpoint is correct cannot be conclusively proved a t this time.
VOL. 30, NO. 9
One important distinguishing feature between a good and bad paint lies in how well the tensile strength and distensibility are maintained as the age of the films increases. I n order that data might be available, a series of tensile strength-elongation measurements was made to determine the modifying influence of the phenol-aldehyde resin BR254 on the active distensible life of varnish films. A series of films was made from the following cooks, all taken to the same stage of silky string: straight linseed oil, linseed oil 5 per cent BR-254 resin, linseed oil 10 per cent BR-254 resin, and linseed oil 20 per cent BR-254 resin. Because of lack of time it was necessary to use heat as an accelerator of the aging rate. Inasmuch TABLEI. CHANGES IN CONSTANTS OF LINSEEDOIL DURING as temperatures of 260" F. (127" C.) and 302" F. COOKING AT 560' F. (293' C.) (150' C.) were to be employed in force aging, it was --Time-- -Iodine Value-Refractive Index.---Density--, % of % of % of necessary to provide some method other than the Sample &if Obtotal 0bNo. Min. time served change served nzkd used amalgamated tin f3LUface. 0 Morrell (3) mentions briefly that mercury can be 0 1 4802 0 0 0 183 0 0 923 47 6 1 4809 1 13 4 173 7 15 0 925 5 1 used to remove films by inducing amalgamation after 62 0 1 4828 26 5 2 88 29 170 0 932 25 6 57 170 62 o 1 4852 51 o 3 172 53.8 coating has been formed on a tin. The method o 944 81 0 1 4879 78 6 4 228 76 166 0 954 79.4 5 300 loo 162 loo o 1 4900 100 0 962 100 0 recommended is slow, frequently requiring a day or more. The procedure below has the advantage that films of 2 to 3 square feet in area can be removed in 10 minutes or less. A study of the solubility of the polymerized product reThe various samples were prepared in the following manner: veals no distinct indication of the presence of a subfitance 100 cc. of cooked varnish were thinned with 140 cc. of Solvesso differing in solubility in any way from the original materials No. 2 and filtered, and 2 cc. of a soluble lead-cobalt naphtheor the normal products made by heating them. nate drier were added. This quantity of drier is equivalent to Iodine numbers were determined on the oil at five stages 0.25 gram of cobalt and 2.06 grams of lead to each gallon of during the progress of the cook. The marked decrease in undiluted varnish (0.0069 per cent cobalt and 0.057 per cent this number at the start of the cook was very distinct ( 2 ) . lead by weight). Table I and Figure 7 show how this property fails to follow the course of other properties. Inasmuch as this same type of change has been found with China wood oil, it is worth while to remark that (with the exception of the first few minutes of heating) in every case the change in direction of the iodine number is opposite to the other two. Here is an excellent opportunity for careful study of the course of polymerization.
+
+
+
Tensile Strength of Films Tensile strength, elongation, and adhesion are closely interrelated. A varnish may possess excellent properties on two counts, yet failure may result because of a lack of the third. Therefore, it is the problem of the manufacturer to design or blend his materials in such a manner that they possess all three traits in a degree adequate to meet the requirements of the particular service conditions under which the paints and varnishes are to be employed. It is common knowledge that China wood oil varnishes give excellent films when viewed from the standpoint of strength, hardness, and chemical resistance. Yet excessive strength is of little avail, for failure generally results because of insufficient elasticity accompanied by poor adhesion. Turkington, Moore, Butler, and Shuey (10) investigated this problem and found that, by adding variable proportions of linseed oil and BR-254 resin to China wood oil, the desirable traits of each constituent may be so graduated as to produce a greatly improved material (10, 11, 12). The ability of a paint or varnish to act as a protective coating is dependent on how well the integrity of the protective film is maintained. Since the surfaces coated are always subject to dimensional variation, it is essential that the protective coating placed upon it be capable of expanding and contracting with the undersurface. If the paint film does not possess this property, failure is inevitable as is evidenced by rupture of the film surface. The result is excessive cracking and checking commonly associated with paint and varnish failure.
FIGURE8
The thinned varnish was flowed onto well-cleaned tin plates, placed vertically in an oven, and baked at 260" F. After 7.5 hours the films were removed and stripped from the tin plate in the following manner : A strip about '/s inch in size was cut with a knife along three sides of the rectangular film, mercury was placed in this groove, and amalgamation was allowed to set in. If there were areas in which the mercury was not prone to amalgamate, they were accelerated by being scratched with a knife blade. After 5 minutes the mercury penetrated some distance beneath the film; the narrower portion of the rectangular film was gently pulled up and a glass rod inserted under-
INDUSTRIAL AND ENGINEERING CHEMISTRY
SEPTEMBER. 1938
neath. (This prevents accidental tearing during pulling.) By tilting the tin so that the excess mercury flows in the direction of the stripping, a narrow thread of mercury will be constantly present a t the junction of the plate and unremoved film. I n this manner amalgamation proceeds at a rapid steady pace, and by gently pulling on the glass rod the film is removed. I n the event that the mercury thread diminishes too much i t is a simple matter to pour on a few additional drops.
989
The tensile strength of all films appears to increase with age; the elastic properties, after having first arrived a t a maximum value, tend to decrease. However, there is a characteristic difference between the distensible properties of straight linseed oil and that containing this resin. The introduction of resin has increased the distensible life of the film, for at the last point investigated the oils with resin content possessed a distensibility which was roughly 250 per cent greater than that of the very brittle straight linseed oil. There appears also to be but little change in this ability to stretch as the aging increases from 220 hours onward. The ability of this resin to impart this property means that the active life of coatings will be prolonged, whereas the straight linseed oil would by now have failed, cracked, and checked. Some difference of opinion exists as to whether the maximum elongation measured or the average presents a truer picture of the extensible properties of a film; it is argued that a slight imperfection in the side of the test sample may produce low results (7). On viewing the present data a t a baking time of 100 hours a t 260" F. plus 160 hours a t 302" F., we find that the maximum value for straight linseed oil was 4 per cent, that of 5 per cent resin was 16 per cent, the 10 per cent resin showed 10 per cent, and the 20 per cent resin gave a maximum elongation of 21 per cent. If the maximum measured values are the more reliable, the incorporation of resin presents an even better picture of retention of elasticity than that shown in the graph where averages were used. LINSEED
OIL
7 5 % ELONGATION
I
0
I
50
1
100
1
I
/SO
200
in hour5
1 250
300
FIGURE9 Samples having a thickness of about 0.0020 inch (0.0051 cm.) were taken from the films, placed in a constant-humidity room, and maintained a t a temperature of 20" C. and a relative humidity of 55 per cent for 24 hours to ensure attainment of equilibrium conditions in moisture content. The tensile strengths and elongations were measured by means of a Schopper tensile tester adjusted in such a manner that the load was applied a t a rate of 400 grams per minute. Rectangular test strips were carefully cut with a razor blade; they were 1.27 cm. wide and long enough to permit 50-mm. lengths between jaws. Five samples were run a t each period in the forced aging, and the average breaking load and elongation were taken. After the first 100 hours of baking, the temperature was raised to 302" F. (150" C.) and was kept a t that point for the remaining time. Precautions were taken to standardize the following factors which may produce variable results (4, 6, 6, 8): The moisture content was brought to equilibrium in a constanthumidity room. Samples were cut with a razor blade and inspected for imperfections. Loading conditions were constant for all samples. Identical diluents were used to minimize variable plasticizing effects, and the samples were all of the same average thickness. This last precaution is necessary because of the possibility that there would be a great difference in aging rate of thick and thin films. The results obtained are shown in Figures 8 and 9. The values indicated in Figure 9 are the mean of five elongation measurements on each sample. The elongation for the purpose of this paper is defined as the maximum distension before rupture of the film.
25
I
/ / /
1
/
75HOURS AT 26OoF AVERAGE 36.8% ELONGATION AT 12 6 KG/SQ CM 2 9 2 %/KG
3 2 HOURS AT 260'F AVERAGE 4 8 6 % ELONGATION AT 2 7 8 KG/SQCM I 75 % /KG.
9 5 % LINSEED OIL- 5 % BAKELITE
100 HOURS AT 260°F AVERAGE 41 8% ELONGATION AT 90 3 KG /SQ CM 046%/KG
BR-254
7 5 %ELONGATION
50
/ /,
/
/
/
25
Z5 HOURS AT 260'F AVERAGE 56 % ELONGATION AT I73 KG /SO CM 3 25%/KG
32 HOURS AT 260'F AVERAGE 49.8% ELONGATION AT 26.9 KG /SQ CM 1.85%/KG
100 HOURS AT 26OoF AVERAGE 5 7 6 % ELONGATION AT 870 KG/SQ CM. 0 66 % /KG
FIGURE 10. SPECIMEN DUPLICATE GRAPHSFROM TENSILE FORMOF CURVESAND TYPE AGREEMACHINESHOWING MENT OBTAINED The abscissas (i. e . , tensile strength) are not plotted on an identical scale.
Figure 10 shows copies of actual stress-strain graphs produced on the machine. It illustrates both the change in form of the curves with aging and the agreement between individual tests. As the corrections for slight variations in thickness and change in pendulum weights have not been applied, the tensile strength (horizontal) values may not be exactly commensurate. For the sake of brevity, only oil and 95 per cent oil-5 per cent resin are shown a t the first three periods of aging. The later graphs flatten out until they are almost horizontal lines.
INDUSTRIAL AND ENGINEERING CHEMISTRY
990
On inspecting the stress-strain curves of the various resin lengths, it was found that there was a characteristic outward bend or S-shape of the curves, which indicated that these materials actually became stronger on stretching. Such action is characteristic of high-grade spar varnishes and is a desirable quality in varnishes which are to be used for outdoor exposure (7). At no stage did the straight-oil film show the greatest elongation at rupture or the greatest elongation per unit of load. TABLE11. FILM COMPOSITIONS SHOWING HIGHESTAVERAQE ELONGATION AT DIFFERENT AGES ---Treatmen& Time, Temp., hours O F. 4 260 7.5 260 32 260 100 260 100 25 100 120
;:I
100 160
gig)
% Resin
BR-254 40 20 20 5
lo
Av. Elongation,
%
% ’ of Oil Film Value
... 225
7.4 82.7 71 57.6 31.2
146 137 124
Elongation of StraightOil Film, %
...
36.8 48.6 41.8 25.2
5-20
9.6-9.4
295-289
3.25
5-20
7.4-7.8
221-233
3.35
Table I1 shows the values for elongation a t rupture of the compositions giving the highest values, and of the straight linseed films for comparison. The elongation per unit of load averaged for all ages 161 and 144 per cent of the value of straight-oil films in the 5 and 10 per cent resin films, respectively. This increase in the flexibility of the oil film a t low concentration of this particular resin has been observed under many conditions and in various industries.
Alkali Resistance The various varnish compositions were diluted with Solvesso No. 2 until they all possessed a specific gravity of 0.91. Glass test tubes, 2.5 X 15.2 em., were dipped into the varnishes and were placed bottom up in an oven to dry a t B temperature of 150” F. (66 C.). On being removed from the oven, they were immersed to a depth of 3 inches (7.6 em.) in a solution of sodium hydroxide in distilled water (1). The tests were conducted in a constant-temperature room maintained at 25” C. and 60 per cent relative humidity. Two series of tests were made a t different periods of drying with different concentrations of alkali. The first were con-
VOL. 30, NO. 9
ducted on 90-hour films in 5 per cent alkali. Almost immediate failure resulted with the straight linseed, 5 and 10 per cent phenolic resin, and 20 per cent ester gum. The 20 per cent phenolic resin whitened in 2 hours and was completely removed from the test tube in 168 hours. The 40 per cent phenolic resin showed no trace of failure in 288 hours. A second series was run on 160-hour films in 1 per cent alkali. The straight linseed oil failed completely within 2 hours. At 5 hours the 5 per cent phenolic resin and 20 per cent ester gum had failed. At this time the 10 per cent phenolic resin was cloudy and exhibited complete failure a t 49 hours. The 20 and 40 per cent phenolic resin films showed no perceptible signs of chemical action a t the expiration of 75 hours.
Boiling Water For determining the resistance to boiling water, flow-outs were made on tin plate and dried for 90 hours at 150’ F. The panels were inserted into distilled water, and the temperature was raised to boiling. Failure was taken when the films exhibited a permanent whitening. Straight linseed oil, 20 per cent ester gum, and 5 per cent BR-254 resin all failed within 27 hours. The 10 per cent BR254 resin failed in 40 hours, and the 20 and 40 per cent BR-254 resin within 45 hours.
Literature Cited (1) Am. Soc. Testing Materials, Rept. Comm. D-I, Preprint 67,
p. 24 (1935). (2) Galdwell, B. P., and Mattiello, J. J., IND. ENQ.CHEM.,24, 158 (1932). (3) Morrell, R. S., “Varnishes and Their Components,” p. 272, London, Henry E’rowde and Hodder and Stoughton, 1924. (4) Nelson, H. A., Proc. Am. SOC.Testing Materials, 21, 1111 (1921). ( 5 ) Nelson, H. A.,Ibid.,23, I , 290-9 (1923). (6) Nelson, H. A., and Rundle, G. W., Ibid., 23,11, 356-68 (1923). (7) Nelson, H. A., and Rundle, G. W., New Jersey Zinc Co., Research Bulletin, March, 1930. (8) Rundle, G. W., and Norris, W. C., Proc. Am. SOC.T e s t i n g Materials, 26,Part I1 (1926). (9) Shuey, R. C., Paint Oil Cliem. Rev., 98 (12), 9 (1936). (IO) Turkington, V. H., Moore, R. J., Butler, W. H.. and Shuey, R. C., IND.ENQ. CHEM.,27, 1321 (1935). (11) Turkington, V. H., Shuey, R. C., and Butler, W.H., Ibid., 22, 1177 (1930). (12) Ibid., 23, 791 (1931). RECEIVED September 23, 1937. Presented before t h e Division of P a i n t and Varnish Chemistry at the 94th Meeting of t h e American Chemical Sooiety, Rochester, N. Y., September 6 t o 10, 1937
FOURTO SIX PER CENT CHROME STEELPREFABRICATED HEADER The header diameter is 14 inches. The nozzles are concentric and eccentric types. All ends are fitted with ring type lap joints. The welding elbow is made of the same material as the pipe.
Courtesy Grinnell ~ o m p a l l yInc. ,
