Vol. 20, KO. 7
INDUSTRIAL AND ENGINEERING CHEMISTRY
674
Manufacture and Use of Amberol-Type Resin Varnish’ A. E. Stauderman and H. L. Beakes PEASLEE-GAULBERT Co., LOUISVILLE, KY.
URING the past two or three years the perfection and production of quick-drying varnishes, enamels, and paints has claimed the attention of more paint and varnish manufacturers and technicians than any other single thing in the history of the industry, with the possible exception of nitrocellulose lacquers. The trade demands speed; yet speed must be coupled with safety to insure protection as well as satisfaction to the ultimate user. The quick-drying type of varnish and enamel is especially suited for this purpose, being fast in drying, easy to apply, and durable. Choice of Oil
D
When the first synthetic resin was submitted to this laboratory, little or nothing was known of its character or qualifications. On melting the gum with linseed oil, while resin melted easily in the hot oil and retained a light color, it did not respond very well to ordinary driers and the resulting varnish was slow-drying. It made very little difference in color whether the resin was cooked with the oil and carried all the way, or the resin was dropped into the cooked oil which was cooling. There was a slight color advantage in favor of the second method. The resin was next melted in wood oil, and it soon became evident that it did not retard the polymerization of China wood oil; however, when melted in wood oil a t about 450’ F. (232” C.), using a small amount of cobalt linoleate, excellent drying resulted. With this in mind, the problem of cooking the resin in all wood oil presented itself. There was little difficulty in holding the wood oil a t the low temperature of 450” F. (232’ C.), and when combined with suitable driers (cobalt linoleate was used in this instance) a fast-drying varnish resulted. The body of the varnish was quite thin-viscosity “C”-and not gas-proof. As the writers were determined to make a varnish of all wood oil and without adulterants of any kind, if possible, they did not wish to incorporate rosin into the manufacture. This they knew would eliminate a lot of danger in the manufacture of the varnish in the factory, but the resultant film was poor. From indications thus far, the resin seemed full of possibilities if the correct manipulation and combinations could be effected. Specifications for Varnish A definite basis for work was then outlined. The formula in this case was for a general interior and exterior varnish as follows: 100 pounds of Amberol (B. S. l), 30 gallons of China wood oil, and 51 gallons of thinner (approximately 50 per cent). The color was to be as light as possible and body wanted was “G” viscosity (Gardner-Holt). Drying time was to be as quick as possible; it was hoped to attain a speed of drying of 4 to 6 hours. Driers The question of the most effective driers to use was now considered, Tests were made on all available driers. It Presented under the title “Research, Manufacture, and Use of the Amberol-Type of Synthetic Resin Varnish” before the Division of Paint and Varnish Chemistry a t the 75th Meeting 01 the American Chemical Society, St. Louis, Mo., April 16 to 19. 1928. 1
was found that litharge was too slow; overnight drying was the best that could be obtained. Lead resinate required 18 hours; lead acetate, 18 hours; manganese resinate, 22 hours; manganese borate, 24 hours; cobalt linoleate, fair drying, 6 hours, but tending to skin-dry; cobalt acetate, 4 hours, but tending to skin-dry; cobalt resinate, slow, 8 hours. Litharge in any combination had a tendency to darken and cloud the varnish. Lead could not be used alone in any form as the drying time was much too slow. Manganese compounds, while light in color, did not accelerate the drying time when used alone. Cobalt compounds naturally darken the varnish, but had better drying qualities than either lead or manganese, although the tendency was to skin-dry. I n 2 hours the varnish had apparently dried, the surface being as smooth as glass, but the film was cheesy. The best possible combinations of driers were then studied and the results are given in Table I. Table I-Drying DRIER
Tests on C o m b i n a t i o n s of Driers METAL^ VISCOSITYDRYING TIME Per cent Hours 0 . 4 8 Pb 6 0.01 M n ] 0 . 2 5 Pb S 0.05co D 0 . 5 Pb 8 (tacky) 0.02 M n ) E
Litharge Manganese resinate Litharge Cobalt acetate Litharge Manganese borate Lead acetate 0 . 3 Pb Manganese resinate 0.15Mnj Lead acetate 0.4 Pb Cobalt acetate 0.05co Manganese resinate Cobalt acetate Lead reqinate 0 . 5 Pb Manganese resinate 0.2 M n ] 0 . 5 Pb Lead resinate Manganese resinate 0.03 M n Cobalt resinate 0.02 c o a Metallic drier figured on total weight of varnish.
1
1
i G
6
8 6 5
41/?
It was soon noted that the liquids containing single metals as drier, while slow in drying, had no tendency to skin over, with the exception of cobalt salts. When combinations of the metals were used, the drying time was greatly improved but skinning became quite pronounced. One might say that this is a natural tendency with a fast-drying varnish, but nevertheless it is objectionable. This m e problem has caused much concern in the manufacture of this grade of varnish. Rosin would serve the purpose well, but the introduction of raw or hardened rosin into the varnish is not desirable, either from a standpoint of durability or speed in drying, notwithstanding the fact that some rosin is used in the manufacture of the synthetic resin mentioned above. Linseed oil, it was noticed, kept the skinning down some, but the amount necessary to use lengthened the drying time. Resinate driers, however, serve a threefold purpose: They prevent skinning to a marked degree with a minimum amount of rosin; they help to keep the wood oil from excessive bodying; and they offer a very efficient way of incorporating driers in wood-oil varnishes. Acetate driers are also very efficient. Volatile Thinners The skinning action was much more noticeable in a halffilled closed can than in a full closed can, or even in an open can. It was therefore decided to investigate the question of volatile thinners. Accordingly, a factory batch was cooked
July, 1928
INDUSTRIAL A S D ENGI*VEERILVGCHEMISTRY
up, using the basic formula previously mentioned, with the most successful drier combination-that is, the last one given in Table I. The highest heat attained was 520" F. (271" C.). Weighed amounts of the hot gum and oil mix were poured into four separate containers and reduced with equal parts by weight, with the following thinners: solvent naphtha, turpentine, benzine, and mineral spirits. The next day samples of each mix were made up as follows: a full can tightly sealed, a half-filled can tightly sealed, and a halffilled can left uncovered. These were examined at regular intervals, and it was found that the half-filled closed can skinned first, in the following order: solvent naphtha, turpentine, benzine, and much later, mineral spirits. The open cans were next to skin and they skinned in the same order. Practically all of the thinner had evaporated from the benzine and mineral spirits cans by this time, leaving only solids. The full can followed in the same order: solvent naphtha, 7 days; turpentine, 12 days; benzine, 20 days; mineral spirits, 25 days. From this it seems that mineral spirits is the best solvent for the varnish, followed by benzine as second choice. Solvent naphtha and turpentine had soft cheesy films, while benzine had a good film, and mineral spirits gave best film as far as drying, hardness, and general appearance are concerned. Adaptation to Factory Operation
Much of the work thus far was carried out in the factory as well as in the laboratory, in order that the factory might keep pace with each new development. Many formulas for varnishes can be successfully made in the laboratory that cannot be duplicated in actual production. This was demonstrated quite early in the development of this varnish. I n the laboratory the temperature can be run up high quickly and cooled off rapidly and excellent results can be obtained; but this is not possible in the factory with normal sized batches of 150 to 200 gallons. One of the first problems encountered was how to keep the wood oil free from globules as well as from polymerizing completely. As the resin has little or no retarding action on polymerization and, as it was desired to avoid the use of rosin, a small amount of semidrying oil was used to retard the action of wood oil. Wood oil can be controlled nicely at high temperatures, with a small amount, say 5 per cent, of a semidrying oil, plus the services of a good varnish maker, without resorting to rosin. This oil does not retard the drying action of the finished product, if used in moderation. This was the first and only radical change in operation in the factory from the methods used in the laboratory. Gas-Proofing
As this varnish was intended for general purposes, inside and outside, the possible effects of gas on the film were considered. Up to this point the varnish was cooked to a maximum temperature of 520" F. (271" C.), but was easily blemished by gas fumes. Therefore in order to avoid trouble due to gas failure, the heat was raised to a gas-proofing temperature. This made the cooking a bit more hazardous, but with careful observation on the part of the varnish maker, little trouble was experienced in holding the varnishes of this type and getting good body. Effect of Temperature on Skinning
To learn the effect of this change in temperature on the skinning of the varnish, two batches of varnish were made up by the formula previously described, one cooked a t a low heat and the other a t a high heat. Weighed amounts of the hot gum and oil mix were poured into separate containers and reduced with equal parts by weight of the following
675
thinners : solvent naphtha, turpentine, benzine, mineral spirits, and a mixture of half benzine and half mineral spirits. The next day samples of each mix were made up as before and examined a t regular interrals. The results are given in Table 11. Table 11-Effect of Cooking Temperature on Skinning LOW-HEATVARNISH HIGH-HEATVARNISH Closed Closed Closed Closed half-full Open full half-full Open full can can can THINNER can can can Days Dayr Days Week.? D a y s Months Solvent naphtha 3 2 6 1 1: 2 8 1 Turpentine 8 Benzine 4 20 3 12 l'/n Mineral spirits 6 $ 25 3 12 3 Half 3 13 3 Half benzine mineral spirits "
4-
1
Use of Hydroquinone to Prevent Skinning
It was found that 0.04 t o 0.05 per cent of hydroquinone added to a varnish that would ordinarily skin in 7 hours would prevent skinning for 6 days. However, the use of such materials involves a great risk. A little too much of the hydroquinone will keep the varnish from drying, and the dried film which has the "anti-skin" mixture incorporated in it shows white in water rather quickly. The use of such materials is not recommended. Characteristics of Synthetic Resin Varnish
From the foregoing it mill be noted that oils, driers, thinners, and cooking all have an important bearing on the manufacture of a varnish of this type-one that will dry in 4 t o 5 hours, give little or no trouble as to skinning, have safe working qualitks, give efficient service. and one that can be made with little or no risk to the manufacturer. The drying time of this varnish is 4 to 5 hours, permitting two coats to be applied in one day. The surface can be rubbed to a beautiful finish in 24 hours, it will stand up under exposure equally as well as hard gum varnishes, and is superior to varnishes made with ester gum. The varnish is gasproof, draft-proof, and when immersed in boiling water for 60 minutes will show no whitening, softening, or blistering. It will stand in cold water indefinitely. Panels have been in water for over 60 days and show no defects outside of a slight dulling which disappears in a few minutes after removal from water. Panels immersed in sodium chloride solutions ( 5 , 10, 15, and 20 per cent) for 4 weeks show no defects in any case. which would indicate varnish to be valuable as a vehicle for marine paints and varnish. It is interesting to note that panels in salt water do not dull even a little bit, while panels in distilled or tap water invariably show a slight bloom or dulling on removal from liquid. The varnish shows considerable resistance to strong alkali, as shown by the following tests: Bright tin-plate panels were dipped in this quick-drying synthetic varnish so that the entire surface was covered, and other panels were dipped similarly into a tung-ester varnish, equally long in oil. The panels were allowed to dry for 48 hours and then placed, thin end of film down, into alkali solutions of various strengths. The resistance to alkali as shown by the time before failure is shown in Table 111. Table 111-Comparison of Alkali Resistance of Synthetic and Tung-Ester Varnishes SaOH TUNG-ESTER SYNTHETIC Per cent Hours Hours 61/2 8 2 5 10 15 20 25
4
5'/2
2
4
11/2 11/2 1
4 4
4
INDb-STRIAL A K D ENG1NEERI.VG CHEAWISTRY
676
It is clear that the synthetic varnish has an advantage over ester gum varnishes of the same length in this respect. Effect of Successive Coats
To determine whether or not successive coats have any effect on the film, exposure tests were made on iron panels, which were recoated after intervals varying from 4 to 72 hours. All panels received at least one coat of the same varnish, one panel receiving one coat only to serve as check panel. No cracking, checking, or blistering was noted on any panels. Panels recoated in 4 hours were as good as those coated after 72 hours, and as free from blemish as the panel which had only one coat. This would indicate that a second coat may be applied in 4 hours with safety. Panels have also been recoated in 2 hours and are equally as good in appearance as those recoated after 72 hours. Panels have since been exposed that have been given as many as five coats in a day-30 or 40 minutes elapsing between coats-and no defects have shown up yet, although panels have been exposed for BO days. Use of Synthetic Varnish in Paint-Mixing
As might be expected, such a liquid is of immense value to the paint grinder, being neutral t o almost all pigments except zinc and umber. Its use in the paint factory is almost unlimited. Primers, surfacers for wood and metal, undercoaters, and enamels are possible with the same liquid. Satinfinish enamels can also be made with the same form of varnish with slightly different kettle manipulation. A set of panels was prepared on wood and steel as shown in the accompanying table. Panels were prepared so as t o leave exposed about 2 inches of each coat to the weather. Only one coat of each material was applied. Absolutely no failure on any one of the exposed undercoats was noticed. After 9 months of exposure facing south a t an angle of 45 degrees, the lacquered panels, 3 and 4, showed a better state of preservation than the clear
Vol. 20, No. 7
varnish coated panels, 1 and 2, and slightly superior to enameled panels, 5 and 6, although these last two were by no means poor in appearance. PANEL
1 and 2
i1
MATERIAL Primer Surfacer Surfacer Japan Rubbmg enamel Clegywearing
i Primer
1 Surfacer
5 and 6
1
Lacquer enamel Lacquer enamel Primer Surfacer Surfacer Enamel Enamel
NATURE TIMEBETWEEN COATS Synthetic 4 hours Synthetic 4 hours Synthetic Overnight Not synthetic 1 hour Synthetic rubbing Overniaht and rubbed Synthetic Svnthetic Synthetic Synthetic Automobile Automobile Synthetic Synthetic Synthetic Synthetic Synthetic
Exposed after 6 hours 4.~ hours . . . ~
Overnight 4 hours 2 hours Exposed next day 4 hours 4 hours Overnight 4 hours Exposed next day
The undercoaters stood up without showing any signs of deterioration, and lacquer did not lift film or have any damaging effect on the surfacers, which had only dried 4 hours before lacquer was applied. This fact indicates the practicability of fast-drying undercoats of this variety for use under lacquer coatings as well as under varnishes and enamels. Conclusions
Turpentine, the natural solvent for almost anything in the paint and varnish industry, is not conducive of good results in the manufacture of this type of varnish. The use of certain types of driers and thinners has a great effect upon the subsequent manufacture, skinning, and drying of this varnish. The age-old theory of not recoating before the previous coat is entirely dry does not seem to apply with this type of varnish. The adaptability and efficiency of this one type of synthetic resin varnish is an indication of the possibilities that such liquids have when used for straight varnish coatings or as a paint grinding vehicle.
New Indicating Equipment for Industrial pH Measurements’ Henry C. Parker LEEDS & NORTHRUPCOMPANY, PHILADELPHXA, PA
ITHIN the last few Three new potentiometers are described which are required. These impressions suitable for making industrial H-ion measurements. are far from the truth and it years potentiornetTwo of these have scales which are direct-reading in is now possible for an average ric H-ion measureoperator to read over a set of pH. The technic required for making measurements Dents have been 80 far simwith industrial types of quinhydrone and hydrogen directions, make up a calomel plified as to be practical for electrodes is described. The limitations regarding the cell from commercially purimany industrial uses, This use of the quinhydrone electrode and the relative fied chemicals, and make a simplification has r e s u l t e d suitability of H-ion and conductivity measurements H-ion measurement t o a high primarily from the introducdegree of precision in a reare di5cussed. tion of portable direct-readmarkably short time. ing potentiometers, improveIn the following paragraphs there will be described some of ments in the design of electrodes and calomel cells, and from the development of the quinhydrone electrode. The industries the new potentiometers which have been developed, towhich make use of H-ion measurements are only just beginning gether with the simplified technic with which it has been to appreciate the advantage of potentiometric measurements, found possible to obtain H-ion measurements with an ease and it still seems to be the general impression that elaborate and accuracy consistent with industrial requirements. purification of chemicals and complicated calculations are ReIative Suitability of Conductivity and H-Ion 1 Received March -..~~. ~~
~
~
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26. 1928. ~~
Presented under the title “Auulication ..
of New Indicating Equipment in Making Industrial Measurements
Of
€3
Ion Concentration” before the Division of Industrial and Engineering Chemistry a t the 75th Meeting of the American Chemical Society, St. Louis, Mo., April 18 to 19, 1928.
Measurements
The distinction between H-ion and conductivity measureacids Or bases is not for determining clear. In some cases either measurement would prove
