IlVDUSTRIAL AND EXGINEERING CHEMISTRY
February, 192i
Table V-Fuel FUEL
RUN
BOILING POIKT RAXGZ O F ~ U E L
c. 150 153 141 148 194 179 175 158 182 201 136 143 193 194
‘
n-Hexane n-Heptane %Octane Benzene To I u en e Xylene Methanol Ethyl alcohol Amyl alcohol Ethyl ether Toluene Toluene Toluene Toluene AVERAGE
67--67.6 98.7-98.9 124-124.3 80.36 (99%) 111 (98%)139 65-6 I 78.4 127-131 35 (99%)111 (99%b)lll (99%)111 (997o)lll
285
C o n s t i t u t i o n a n d R a t e of Rise of Pressure ANALYSES OF PRODUCTS OF COMBUSTION
SpECIFIC
GRAVITY
AV.
I.bs./sq. in. Lbs./sq. in./scc. Lbs./sa. . . in. Sec. 0.6639(*0/15) 675 0.0195 47,500 34,600 61,500 37,400 0.6893(20/20) 655 0.0175 63,700 40,550 0.7123(20/20) 668 0.0165 63,000 43,400 0 . 8 7 9 (20/~0) 665 0.0153 56,500 38,200 0.8598(25/15) 650 0.0170 35,500 47,000 0 . 8 6 0 (25/15) 676 0.0190 52,000 36,100 0.7864(25/15) 705 0.0195 39,500 30,900 0 . 7 8 9 (20/z0) 650 0.021 48,000 33,700 0.815 (15/~0) 676 0.020 48,400 0.719 (15,’~) 665 0 . 0 1 3 7 5 >200,000 58,000 37,500 0.8598(25/15) 675 0.018 57,000 38,800 0.8598(25/15) 660 0.017 56,000 3R,200 0.8598(25/1s) 650 0.017 56,500 38,200 650 0.017 0.8598(25/15) 659 1 56.125 38,175 I
Conclusions
Comparison of the data reported in Table V indicat,es that, a t least with the fuels tested, the rate of rise of pressure in a progressive homogeneous reaction 1-Increases with molecular weight in the paraffin series. 2-Varies inversely with the number of methyl groups added to the benzene ring in the aromatic series. 3-1s approximately t h e same for normal octane and benzene; for normal heptane and toluene; and for normal hexane and xylene. 4-1s about the same for the higher alcohols as for the corresponding paraffin hydrocarbons. 5-1s exceedingly rapid for ether.
CnHzn
OZ
CO
%
70
%
70
70
70
%
17.0 18.9 19.7 21.6 22.0 21.3 18.4 19.0 19.5 18.5
0.0 0.0 0.0
1.5 1.2 1.5 1.4 1.8 1.3 1.6 1.3 2.1 1.3
1.8 1.3 0.2 0.9 1.4 1.3 1.4 0.6 0.2 0.1
2.1 1.2 1.1 0.4 0.9 0.8 1.8 0.7 1.4 0.4
0.1 0.3 0.1 0.0 0.4 0.1 0.0 0.1 0.2 0.0
77.5 77.1 77.4 75.5 73.5 76.0 76.8 78.3 76.6 79.7
..
.
22.3 22.2 22 0
0.2 0.0 0.2 0.0 0.0 0.0 0.0
...
0.0 0.0 0.0
...
1.6 1.9 1.8
...
0.2 1.4 1.4
Hz
...
0.8 1.5 0.9
CHI
Nr
COZ
...
0.2 0.0 0.4
...
74.9 73.0 73.5
It is well known that the aromatic hydrocarbons do not “knock” in internal combustion engines so readily as do the paraffin hydrocarbons. When the data reported in this paper are interpreted with this fact in mind, it is evident that the rate of rise of pressure in a progressive homogeneous explosion cannot be the sole factor determining the tendency of a fuel to knock in an internal combust,ion engine. The same conclusion is suggested by data previously reported on the effect of initial temperature on the rate of rise of pressure.6 A later paper will suggest another factor which, taken into consideration with the rate of rise of pressure, is adequate to explain engine knocking.
Preparation and Properties of Esters of Congo and Manila Resins’ By W. T. Pearce, Robert Carlson, and C. L. Rydstrom SCHOOL OF CHEMISTRY. XORTHD A K O T AGRICULTURAL A COLLEGE, F A R G ON. , D
I
N THE manufacture of enamels, varnishes of low acid
value are required as vehicles for the basic pigments. If varnishes of high acidity are used, changes in consistency will occur, producing “livering.” Inasmuch as the constituent of the varnish possessing high acid value is the resin, i t is necessary to use resins which yield on melting a product of as low acid value as possible. When heated in a varnish kettle until oil-soluble, some resins,2 such as kauri and East India, give products of low acid value. Congo and Manila, on the other hand, are examples of the type which give products of high acid value. Varnishes made from them a r e so acid that their use as vehicles is limited to certain pigments. Brende13 secured a low acid non-livering varnish by esterifying Congo with a quantity of glycerol equal to 10 per cent of the resin taken, using methods similar to those in use for the manufacture of ester-gum (glyceride of rosin). He ground small quantities of zinc oxide and ocher in this varnish, using a mortar and pestle. When these were thinned to painting consistency no thickening was observed for 8 days. I n some experiments with Congo, Manila, and Pontianac, 1 Presented before the Section of Paint and Varnish Chemistry a t the 72nd Meeting of the American Chemical Society, Philadelphia, Pa., September 5 to 11, 1926. Unpublished work b y W. T. Pearce, performed in 1921; Rhodes and Johnson, THISJ O U R N A L , 14, 279 (1922). 3 Farben-Zip., 29, 231 (1923).
Gardner* found that the mixture of glycerol and molten resin changed to a thick gummy mass (polymerized), unless the resin was cooked sufficiently (1.25 to 1.5 hours). He likewise ground zinc oxide with his varnishes, and noted that no thickening took place upon standing 8 months. Object of Investigation
The present work was initiated to study the several factors involved in the manufacture of esters of Congo and Manila resins. These included loss in weight upon heating to prevent solidification, and the procedure required to secure a product, which would make a light-colored varnish. It was also planned to study the changes in consistency of enamels made with these resin-ester varnishes. Methods of Investigation
The work was done on good grades of Congo and Manila resins. Glycerol (85 per cent) was used for the alcohol. The esterification experiments were conducted in Florence flasks, in glass and copper beakers, and in 8-liter copper and monel metal varnish kettles. I n several cases, covers and condensers were used with the beakers. The resin was broken into pieces varying from 0.5 to 1 inch in diameter, depending upon the size of the container. I n order to determine the speed of the reaction, acid values were determined on samples taken a t 30-minute intervals. 4
Paint M f r s . ’ Assoc. U .S.,Tech. Circ. 161.
INDUSTRIAL AND ENGINEERING CHEMISTRY
286
J
Varnishes made from these resins were tested by the usual methods. Enamels were made by grinding zinc oxide, lithopone, ocher, Prussian blue, titanox, and asbestine separately with some of the varnishes. T o determine the rate of thickening, consistency measurements were made a t intervals of 1, 2, 7, 28, and 364 days. MEASUREMENT OF RELATIVECONSISTENCY-The change in consistency was measured by recording the time required for three drops of the enamel to flow a distance of 5 cm. A flat glass plate with two lines drawn on the reverse side, 5 cm. apart, was used. A spatula with a tapering 7.5-cm. blade was dipped into the enamel, which was allowed to drop on the glass plate, just touching one of the lines. The plate was quickly placed in a vertical position, and the time for the enamel to flow to the other line was recorded with a stop-watch. The method is obviously inaccurate, but when performed in the same way by one worker, it gives fairly comparable results for a certain enamel. The writers felt that it recorded the change in consistency of one enamel sufficiently accurately for the tests. Experimental Work SERIES1-The apparatus consisted of a 700-cc. glass beaker, a glass stirrer, and a tin cover, to which a tapering tin tube was soldered. This tube was 12 cm. long and 2 cm. in diameter a t the end soldered to the cover and 1.25 cm. in diameter at the other end. The condenser thus formed was long enough to condense most of the glycerol, and short enough to allow the water formed during the esterification to escape. A 100-gram sample of the resin was heated to 200' C. in this apparatus, and held a t this temperature until melted, when the temperature was allowed to fall t o 178" C. After addition of 10 grams of glycerol the temperature was gradually raised to 325" C. The mass was frequently stirred throughout the process. Solidification took place in 30 minutes, followed by liquefaction after a period of continued heating for 35 minutes. Samples were taken a t this point and after 30 and 60 minutes of further heating. The experiment was repeated several times with catalysts For this purpose, 2 grams of aluminum, nickel, copper, and zinc. and 0.5 gram of the acetates of lead, nickel, and cobalt were used separately SERIES2-A 500-cc. Florence flask and glass stirrer, without cover or condenser, were used in the second series. Experiments were made with 100 grams of Congo with no catalyst and with the same quantity of resin with 2 grams of aluminum. Solidification occurred in 20 minutes, and an SO-minuteperiod of continued heating was required to liquefy the product. To ascertain whether the addition of varnish oil would prevent solidification and give a varnish of low acid value, 100 grams of hot alkali-refined linseed oil were added just before the time for solidification. No solidification took place and the product became homogeneous in 40 minutes. It was then bodied, cooled, and thinned with turpentine. Four varnishes were made in this way, using 2 grams of aluminum as catalyst. On a larger scale, with an 8-liter copper varnish kettle, copper cover, and tin tube condenser, 25 cm. in length, 500 grams of Congo were taken and the oil added just before solidification. The results were comparable with those obtained in the Florence flask, except that the products were somewhat darker and had a little higher acid value (color, 10; acid value, 10). SERIES3-An 8-liter monel metal kettle without cover was used. The Congo was heated until a loss of 25 per cent was obtained, when the glycerol was added and the procedure carried out as in Series 1. No solidification occurred. In many cases the molten ester was made into varnishes. SERIES &-Experiments similar to Series 1and 2 were conducted upon Manila resin. Solidification occurred much more quickly than in the case of Congo, and continued heating for as long as 2 hours failed to produce liquefaction. When experiments similar t o Series 3 were made no solidification was found.
Data Milky Congo (acid value, 106) was used. When heated in the apparatus described in Series 1, it became molten, when it had lost 14 per cent by weight, and gave a product having an acid value of 79.
T a b l e I-Acid CATALYST None Aluminum Nickel Copper
ACID
Vol. 19, s o . 2 Value of Esters, Series 1
VALUE
CATALY5T
ACIDVALUE
Zinc Lead acetate Nickel acetate Cobalt acetate
41 20 19 33
27 20 19 33
Remarks-The esters were somewhat darker than the "run" Congoi. e . , Congo heated until oil-soluble. I n the case where no catalyst was used continued heating gave products having acid values of 38 and 34 for periods of 30 and 60 minutes, respectively, after liquefaction. When catalysts were present, continued heating did not lower the acid value.
I n Series 2, the esters were as light as the "run" Congo. The ester obtained without a catalyst had an acid value of 8; when aluminum was used, the ester had an acid value of 6. T a b l e 11-Constants ACIDVALUE
4 3 6 6
COLOR
9 8 6 5
VISCOSITY
Poises 1.20 1.00 2.00 1.00
of Varnishes. Series 2 OIL
TEMPERATURE
= Linseed Linseed Tung Tung and linseed (1:l)
c.
326 276 226 226
In Series 3, the acid values of the esters secured varied from 8 to 15. The catalysts listed in Series 1 had little effect upon the acid value of the esters. The varnishes had acid values varying from 4 to 6, and color values of 10 or above, being very similar to those listed in Table 11, but somewhat darker in color. In Series 4, the Manila esters, with acid values between 18 and 25, were secured, the catalyst producing negligible effect. They were somewhat darker than Congo esters. Esterification for 90 minutes before addition of the oil gave a varnish with an acid value of 5, a viscosity of 1.00 poise, and a color value of 10. Experiments with Varnishes The varnishes were tested by the water, draft, and kauri reduction methods. They were very similar, and varied chiefly in color and acid value, all passing the 10 or 20 kauri reduction test. Enamels were made from each varnish, with zinc oxide, lithopone, ocher, Prussian blue, titanox, and asbestine, respectively. To 25 grams of the pigment on a 25-cm. circular glass plate, sufficient varnish was added to make a paste. This was ground 150 times with a glass pestle, nearly flat a t bottom. The paste was scraped u p after each 50 grinds, and then ground with the opposite motion. After this, it was placed in a beaker, thinned to the desired consistency. and placed in bottles. Change in Consistency of Enamels The varnishes whose acid values were less than 6, showed some thickening with zinc oxide, lithopone, and Prussian blue, and practically none with the other pigments. For instance, a zinc oxide enamel required 57 seconds to flow 5 cm. when made and 95 seconds after standing one year. Some showed a greater change in consistency, but all of them flowed out within 4 minutes. The varnishes with acid values between 8 and 12 showed considerable thickening with zinc oxide, lithopone, Prussian blue, and ocher. Conclusions These experiments indicate that a procedure can easily be developed to manufacture varnishes of low acid value from Congo and Manila resins, either directly or through the resin ester. It may be that a product lighter in color can be made, which will be suitable for use in white enamels. By building a special kettle, simulating the Florence flask, it would seem possible that light-colored varnishes of low acid number could be made by driving off only 12 per cent of volatile matter before ederification.
