NOVEMBER, 1935
INDUSTRIAL AND ENGINEERING CHEMISTRY
Mechanism of Isobutane Formation The first product of the polymerization of ethylene must be 1- or 2-butylene, which on hydrogenation should give nbutane. Undoubtedly, under the experimental conditions, a n isomerization of 1- or 2-butene into isobutene ( 2 ) occurs, and the latter, on hydrogenation, gives isobutane. Experiments in connection with this reaction have shown that nbutane does not isomerize into isobutane in the presence of phosphoric acid. The possibility for 1-butene to isomerize into isobutene was shown in the following experiment: Pure 1-butene was heated to 330" C. with phosphoric acid in the presence of hydrogen, the initial pressure of the latter being 100 atmospheres. After heating for 12 hours, a liquid polymer and a gas were obtained, and the latter was subjected to an analysis according to Podbielniak. This gas which was condensable a t -78" C. consisted of 50 per cent isobutane, a small quantity
1369
of n-butane and the unreacted n-butene. The amount of isobutane formed represented 6 per cent of the reacted butene.
Acknowledgment The authors wish to express their thanks to R. C. Wackher for making the carbon and hydrogen analyses and determinations of density and molecular weight.
Literature Cited (1) Francis, A. W., IND. ENQ.CHEM.,18, 621 (1920). (2) Ipatieff, V. N., Ber., 36, 2003 (1903); Ipatieff and H u h n , W., Ibid., 36, 2014 (1903); Ipatieff a n d Sdaitovecky, Ibid., 40 1827 (1907). (3) Ipatieff, V. N., Ibid., 44, 2978 (1911). (4) Podbielniak, W., IND.EKG.CHEM.,Anal. Ed., 5, 172 (1933). (5) Zelinsky, N. D., and Borissoff, P . , Ber., 57, 2060 (1924). RECEIVED January 21, 1935
Natural Resins for the Varnish Industry of its satisfactory performance, is said to have delayed the development of porcelain. C. L. MANTELL, C. H. ALLEN, AND K. R.I. SPRINKEL
Source of Supply and Origin
American Gum Importers' Association, Inc., New York, N. Y.
HE use of the natural resins, either b y themselves or a s a constituent of coating materials for decorative and protective purposes, has been practiced from very early times. It is believed that the Egyptians used natural resins of the balsam type to varnish their mummy cases. It is probable that the natural resin was smeared on. Evidence exists that the Incas of South America employed natural resins for embalming. The properties of resins were known to the Carthaginians, the Phoenicians, and the earliest Greeks. Evidence exists in the form of varnished objects several thousand years old and in excellent condition, that natural resins skillfully applied can yield finishes of outstanding durability. The natural lacquers, which are tree exudations, on Chinese and Japanese carriages, armor, bridges, and temples have withstood long periods of weathering in severe climates. Lacquered tableware, because
T
GUMTREE,SHOWING METHOD OF TAPPING AND TYPEOF NATIVE WITH GUM SPE.4R TAKEN NEAR LENKEON LAKE TOWOETI, CELEBES
I n our present chemical age with its emphasis on synthetic products, there is a tendency to deride raw materials from natural sources. There is a feeling that natural varnish resins are collected by ignorant savages from the ground and limbs of trees in tropical forests, and brought to the market by wily traders operating in an unorganized manner. The actual facts certainlydo not bear out or substantiate any of these impressions. The natural resin business is world wide in its organization; it is conducted in a systematic and organized manner as far as the collection, grading, sorting, preparation for market, and distribution of the product are concerned. It is fully as well set up as a going business as the collection of rubber, the development of naval stores, the production of coconut and palm oils, or the preparation of sugar. The natural resin business is stable and ready to meet any demands made on it. It is not subject to decreasing supplies o r v a n i s h i n g sources of material. I t s art in varnish making is old, well established, and free from patent restrictions and the attendant difficulties of such influences. The natural resins are forest products rather than synthetic materials prepared from
1370
mineral resources. 4 s forest products they are capable of indefinite renewal and for that reason mill probably find continued use in the industry for a much longer period than their present synthetic competitors. The use of the natural resins was developed _almost entirely in connection with the older varnish making -art. Varnish making for nearly a century was hedged in by restrictions, secretiveness, and close guarding of manufactying practices. The influence of such an attitude is reflected id the relatively small amount of published information on natural resins and natural resin varnishes. Some excellent texts succeeded in breaking through this veil of mystery ( 4 , 6 ) . I n tlie last decade or so this viewpoint has undergone a complete change but the natural resins still suffer from an insufficient literature. Recent publications tend to fill the gap ( 2 , 3 ) . The varnish trade usually refers to the natural resins a- gums. I n strict terminology, however, the gums are related to the sugars and carbohydrates; they are soluble in water, forming viscous solutions, and are insoluble in drying oils and organic solvents. On heating they decompose completely without melting. I n contradistinction, the resins are insoluble in water, more or less soluble in organic substances and vegetable oils, and are chemically related to the turpenes or the essential oils, On heating the resins melt with the distillation of volatile oils turpenic in nature. The residue, termed “run” gum or resin by the varnish maker, is soluble in hot vegetable oils. Some of the softer resins are directly soluble in solvents or oils, but in all cases are totally insoluble in water. I n general, the natural resins are divided from the point of use into those which are spirit-soluble (“spirit” originally meant alcohol but now embraces a large variety of solvents) and those which are oil-soluble. The first class is generally soluble directly, while the second needs to be processed by thermal methods. The spirit-soluble resins are in general of the soft variety, while the oil-soluble are usually hard. The resins are known under names which are indicative either of their source of origin, of a distinguishing char-
11
acteristic of the r e h , or of the port a t which they enter commerce. They are further classified into three inajor types: the dammars, the kauris, and the copals. There is a practically continuous series as regards solubility and hardness, from the hardest copals of the fossil type to the softest dammar.; obtained from fresh tappings of living trees. For the purposes of this paper, the natural resins will be understood to include those resins employed primarily in varnishes and finishing materials, but to exclude shellac, rosin, and i t derivatives. The natural resins originate outside of the United States and are therefore all imported. Over the period of 1926 to 1934 the natural resin imports hare been of the order of 38,000,000 pounds annually. For the last qix years the average price has been about 5.7 cents a pound. For the nine-year period the average annual import of copals has been of the order of 23,000,000 pounds, of kauri 3,000,000, and of dammar about 12,000,000. Table I s h o m imports for the past nine years. TABLE I. POUNDS OF RESINS IMPORTED INTO Year
Dammar
Kauri
Copals
THE
U. S.
Total
13,532,100 13,832,100 14,152.900 19,130,914 11,217,100 11,733,593 8,552,535 12,959,928 12,329,000
The natural resins in general originate in the Congo district of Africa (from which the resin is named), S e w Zealand, the Netherlands East Indies, Malaya, the Philippine Islands, and adjacent territory. They are obtained from definite species of trees in a systematic manner, generally under governmental supervision. The major natural resins employed in varnish are given in Table 11.
INDUSTRIAL AND ENGINEERING CHEMISTRY
NOVEMBER, 1935
1371
TABLE 11. SOURCES )F NATCRAL RESINS Class
Boea
Tree
Congo Kauri Manila
Copal-fossil Copal-fossil Copal-fossil Copal
Agathis Alba Copaifera Baathis Australis -4gathiu Alba
Pontianak Batarian
Copal Dammar
Agathis Alba H o p e a , Shorea
Batu Black .Macassar Singapore
Dammar Dammar Dammar Dammar
Shorea Burseraceae Dipterocarpacae Balanocarpus
Major Use
Imported into United States from:
Country of Origin
Oil varnishes Netherlands East Indies Oil varnishes Belgian Congo, Africa Oil varnishes New Zealand Oil and spirit varnishes Netherlands East Indies; Philippine Islands Oil and spirit varnishes Borneo Oil and spirit varnishes Sumatra, Borneo, Java, East Indies Oil varnishes Malaya, East Indies Oil varnishes Malaya, East Indies Spirit varnishes Celebes, East Indies Oil and spirit varnishes Sumatra, Borneo, Malaya, East Indiea
Government Directions Barry ( 2 ) states that in the Xalili district in the Celebes two-hundred thousand trees are tapped under governmental supervision Tvith an annual yield of about 12 kg. per tree. I n Malaya resin collection is directed and controlled by the forestry officials of t'he Federated Malay States. I n S e w Zealand legislative acts passed in 1925 empower the government to control the kauri industry as regards production, export, and grading of the resin. I n t,he Congo the gathering of the resin, its grading, sorting, and marketing is of special concern to the Belgian Ministry of Colonies. Throughout the Ketherlands East Indies the Dutch Government is the directing and controlling authority. All of these organizations are vitally interested in a stabilized, continuing industry with careful plans for the future. The Netherlands East India Government is conducting scientific development in the colonies and has subsidized research programs in Holland and in laborat'ories in the 'C'nited States. The Belgian groups, particularly interest'ed in Congo, are conducting development work in the colony as n-ell as a funded research program at' the University of Louvain. The American importers as a group, under the name of the hmerican Gum Importers' Association, have supported a research and development program in industrial 1aborat)ories in the Unit'ed States for a number of years, and are carrying this work forward as their major activity.
Classification Van De Koppel of the Museum for Economic Botany, Buitenzorg, Java, has proposed a classification of the natural resins ( 8 ) . He has divided the resins int,o those having low acid numbers, which in turn are subdivided into the dammars and the East India fossil or semi-fossils; resins of high acid number from the East Indies, subdivided into the fossil pontianak type and the Manila resins of the soft, half-hard, and hard or fossil varieties; additional classes of African fossils such as Congo; and S e w Zealand Kauris. The classification is as follows: I. Resins of low-acid-number A . Dammar resins: spirit- and oil-soluble, direct acid number 25-45, melting point 90-110" C. 1. Batavian 2. Padang 3. Pontianak 4. SineaDore 5. SuGatra B . East India fossil or semi-fossil resins: oil-soluble, indirect acid number 25-40, melting point 125180' C. 1. Batu 2. Bold black scraped (Dammar Hitam) 3. East India Singapore 4. Hiroe 5 . Macassar East India
Macassar, Netherlands East Indies iintwerp, Belgium h-ew Zealand
East Indian ports; Manila P. I. Pontianak, Borneo: Singauore Batavia, Java Singapore and East Indian ports East Indian ports (Singapore) Macassar, Netherlands East Indies Singapore, Malaya
6. Rasak (pale East India) 11. Resins of high acid number originating in the East Indies A . Pontianak copal fossil resins: spirit- and oil-soluble, indirect acid number 103-140, melting point 135-145" C. B. Manila resins 1. Melengket or soft resins: spirit-soluble, indirect acid number 135-160, melting point 110-135" C. (Macassar) 2. Loba or half-hard resins: spirit-soluble, indirect acid number 140-150, melting point 115-120" C . (:Lobs) 3. Fossil or hard resins: spirit- and oil-soluble, indirect acid number 110-150, melting point 140-155" C. (BoeaLoewoe-Pontianak) 111. African fossil or semi-fossil oil-soluble resins: indirect. acid number 110-135, melting point 140-220" C. (Congo) IV. New Zealand fossil or semi-fossil resins: spirit,- and oilsoluble, indirect acid numher 55-70, melting point 120-160" C . A . Kauri B. Bush Kauri
Properties The properties of the natural resins of major importance for varnish manufacture are given in Table 111. They range in melting point from as low as about 110" to as high as 220" C. In general, their acid numbers after running are considerably lower than that of the original resin. Their softening points cover a range from a little belolv 80" to a little above 130" C. The commercial gradings of one important group, the Manila resins, are shown in Figure l . The market inaterials are sorted and graded according to softness or hardness, color, size, and impurities, with part'icular reference to bark and foreign matter. These gradings and letter designations are those most commonly and widely used. I n preparation for the market, the natural resins pass N ~ T I YBEO ~ 4TV D
USED ON L 4 K E TonoErI TO T R ~ Y S DISTRICTS TO ConCEUTRATION HORSES, THE\ TO C04STiL S H I P P I ~PORTS G
CREW
PORT GUM FROM ISOL4TED POIVTS FOR TRAVSFER TO
INDUSTRIAL AND ENGINEERING CHEMISTRY
1372
VOL. 27, NO. 11
This process is based on the peculiar fact, comparatively little known, that finely powdered hard copal, when masticated on hot roller mills, increases its solubility considerably. By mastication it becomes soft and plastic a t 200" F., and can be rolled out into thin sheets, which in turn can be rolled together again so that masticating can be repeated several times. The mechanical action of the hot rollers is so severe, especially if high pressure by means of closely spaced rollers and temperature of 250' to 300' F. is applied, that the interior structure of the copal is weakened, and that perhaps even the copal molecule is decomposed to some extent. Ac any event, the copal gum improves its solubility remarkably and becomes soluble, not only in cyclohexanol acetate but also in propyl, butyl, and other higher alcohols, as well as in pine oil. The viscosity of the solutions decreases the longer the copal is masticated; for example, Congo copal which has been passed through the rollers twelve to fifteen times in the run of about 30 minutes at approximately 250' F. gives low-viscosity solutions.
N \TIVE Guu COLLECTORS CARRYING THEIRLOADSFROM MOUNTAINS TO LENKE
THE
Each basket contains about 140 pounds of gum.
through a number of grading and cleaning operations, some of which are done by machine but others by hand. These may involve water-washing, screening, ffoating, winnowing, sandblasting, hand picking and sorting, and hand scraping to remove surface coatings. The different materials, depending upon their origin, are received in American ports in bags, boxes, baskets, or cases. They are on the free list of the Tariff Act and therefore pay no import duty.
TABLErrr.
PROPERTIES
Natural Resin Batu, Black bold bold scraped Beraped (Dammar Hitam) Boea,'medium dark Congo hard dark amber Congo: ivory rescraped Copal, DBB Congo, medium soluble pale chips Dammar, standard Batavia E . I. Singapore, pale bold Kauri Yo. 1 brown Maca& (Manila) MA Manila Loba B Pontianak, genuine bold
Recent work has been directed to the study of the chemistry of the running process, so that run gums of predetermined chemical and physical characteristics may be produced. As a corollary, esterification studies have been made, resulting in the production of neutralized run gums which are soluble in oil, mineral spirits, coal-tar solvents, and other thinners. The neutralizing agent in the case of the copals has usually been glycerol, although other organic alcohols such as glycols have been proposed and found some employment. Attention has been directed to the melting of gums, particularly copals, with the exclusion of air in an atmosphere of carbon dioxide. Lighter colored varnishes with better gum melts are stated to be the result. Low-temperature oxidation of the hard fossils in either dry or moist air has been proposed to increase their solubility in solvents. These oxidation methods have not found wide usage, however.
OF NATURAL RESINS
Per Cent hfoisture
Direct Acid NO.
Direct Acid ho. Indi- Soften- h!eltrect ing i?g after Acid Point Point, RunKO. 0 c.' 0 C. ning
3 1.5
2l8 0
33 36
2.9 0.7 1.8 0.4 2 1.2
126 102 92 139 110 26
149 123
5.4 21. 2 1.5
57 141 140 123
0.7
20
111 132 157 32 37 67 148 157 133
132 125 115 104 91 85 90 S5 128 120 95 75 108
The softening points were determined by the mercury method of Durran, as modified by Rangaswami (7). This method gives definite results that can be closely duplicated.
Pretreatment Methods A number of processes have been proposed for the treatment of natural resins prior to their use in varnish. Purification by solution of the resins in solvents, filtration of the impurities, and distillation of the volatile solvents has encountered difficulty in the case of the copals because of the small number of solvents available for this purpose. Such few as dissolve Congo, for example, give very viscous solutions which cannot be readily treated. The situation is quite different, however, in the case of the dammars and the spirit-soluble Manilas. Solvent methods for refining of kauri are employed. The method involving benzene-alcohol mixtures as well as other types of solvents is applied to untreated or run resin. Lightcolored refined products are obtained. Considerable attention has been given to mastication methods for pretreatment of copals. According t o Krumbhaar (6):
Varnish Formulation
For a number of years the American Gum Importers' Association has financed research and development work on natural resins. This work lSo l5 has involved the preparation of nearly five164 17 148 95 hundred different varnishes made from natural 200 78 144 92 resins, modified phenolic formaldehyde resins, 220 119 97 70 (the modification usually being with ester gum or 108 . 9. rosin), and other commercial synthetic resins. 156 The results of this work have been reported in 152 35 120 111 .. .. some detail (1). The varnishes were subjected 141 95 to all of the usual laboratory tests for drying rates, viscosity, hardness, gloss, cold and boiling water, gas-proofness, kauri reduction, and weather tests on wooden and metal panels on exposure racks in Cincinnati and in Florida. The varnishes were formulated of 75, 90, or 100 per cent China wood oil. The natural-resin varnishes showed higher kauri reduction numbers than those of modified synthetics selling in a price range of two to three times that of the natural resins. They showed equal or better gloss. There was definite proof that the China wood oil was the primary cause of rapid drying. Many values which have been widely credited t o synthetic resins in varnish formulation were shown to be actually due to China wood oil, inasmuch as natural resins could be substituted for the synthetics with the preparation of varnishes of a t least equal and in a number of cases superior qualities. The natural resins deserve more attention than they have been receiving, because they offer definite economic advantages. They are cheap, readily and widely available in a large number of grades, and can be processed by modern formulations employing China wood oil and newer solvents, to give high-quality varnishes of excellent weather resistance.
NOVEMBER, 1935
INDUSTRIAL AND ENGINEERING CHEMISTRY
Literature Cited (1) Allen, C . H., a n d Sprinkel, K. M., Drugs, Oils,Paints,Oct., 1934; IND. ENG. CHEM., News IM.,12, 392 (1934); Federation P a i n t Varnish Production Clubs, Oficizl Digest, 143, 54-65 (1935): Ibid., 144, 111-24 (1935). ( 2 ) Barry, T. H., “ N a t u r a l Varnish Resins.” London, Ernest Benn Ltd., 1932. (3) Barry, T. H., and D u n s t e r , G. W., “Varnish Making,” London, Leonard Hill L t d . . 1934. (4) Coffignier, Ch., “Tarnishes, Their Chemistry a n d Manufacture,” London, Scott, Greenwood a n d Son, 1923.
( 5 ) K r u m b h a a r , Wilhelm, J . Oil Colour Chen. Assoc., 17 (1731, 413-36 (1934).
(6) McIntosh, J. G., “ M a n u f a c t u r e of Varnishes a n d Kindred Industries,’’ 2nd ed., Vol. I1 (1908), Vol. I11 (1911), London, Scott, Greenwood a n d S o n ; Livache, A , a n d McIntosh, J. G., Ibid., 3rd ed., Val. I (1919). (7) Rangaswami, M., J . Oil Colour C h e w dssoc., 13, 287 (1930). (8) T a n D e Koupel, C., “ D e H a n d e l in h e t Nederlandsch-Indische copal (Manila-copal) en h e t gebruik er v a n voor verschillende industrieele doeleinden,” Buitenzorg, J a v a , 1934. RECEIVED June 18, 1935. Presented before the Division of Paint and Varnish Chemistry at the 89th lfeeting of the American Chemical Society, New York, 3 . Y., hpril 22 to 2 6 , 1935.
Volatile Matter of Pennsvlvania J Anthracite H. G. TURNER
AND
1373
The composition of the volatile matter of Pennsylvania anthracite was determined by treatment of thirty-six bed samples selected from points throughout the anthracite region, The proximate and ultimate analyses for the samples used and the proximate analyses for prepared coals from all parts of the region are given. The samples tested were heated slowly a t temperatures from 70’ F. to 1900’ F. (21’ C. to 1036’ C.) in a nichrome tube connected to 12 or 15 liters of space evacuated to less than 1 mm. pressure. Hydrogen sulfide appeared in small quantities in every sample of evolved gas. No illurninants were detected. No tar was emitted by any of the coals. The gas contained 75 to 89 per cent hydrogen (average 83 per cent); the average volume of hydrogen was about 5000 cubic feet per ton of coal under standard conditions.
W. L. KEENE‘
Anthracite Equipment Corporation, New York, N. Y.
HE apparatus consisted essentially of a
ENGINEERS TAKINGSAMPLES IN A PENR’SYLVANIA AKTHRACITE MINE FOR EXPERIMENTATION
0.75-inch nichrome tube mounted in an electric furnace and connected to a Hyvac pump. Provision was made for the control and measurement of temperatures and the collection, measurement, and sampling of gases. The anthracite was sized to 10 X 16 mesh and dried 24 hours a t 110’ C.; 50 cc. were measured into a graduated cylinder and then weighed. The coal was placed on a bed of broken silica so situated in the nichrome tube as to bring the sample into the middle part of the furnace. The upper end of the tube was sealed and the lower end \vas connected to a condenser and buret. Both ends of the tube were protected against heat by mean5 of copper coils through which flowed a stream of cold water. The partially dried gas passed from the condenser through a calcium chloride drying tube, through a flowmeter, t o a 12liter sealed flask which was connected to a mercury nianometer and Hyvac pump. ,111 connections were sealed, and the entire system was evacuated t o the capacity of the Hyvac pump, about 1 mm. of mercury. 1
Present address, Rustles8 Iron Corporation of America, Baltimore, M d .
