INDUSTRIAL A X D EAVGINEERING CHEMISTRY
November, 1930
1177
Phenol Resinoids in Oil Varnishes' V. H. Turkington, R. C. Shuey, and W. H. Butler BAKELITECORPORATION RESEARCH LABORATORIES, BLOOMFIELD, N. J.
H E S the varnish industry began turning to synthetic raw materials in the never-ending search for improved quality, it mas only natural that the phenol resinoids should be among the first to receive active consideration. It has long been recognized that the unique combination of properties possessed by these materialssuch as their hardness, waterproofness, and resistance to weathering, acids, weak alkalies, solvents. and many other destructive influencrs-~vhich has made them so valuable in the fields of molded plastics, electrical insulation, and numerous other applications, should also make them of very 9
has given good result's, with the suggestion that the same or similar methods of study niay also be applied with suit'able variations to a very wide variety of varnish and paint problems. The method suggested is not claimed to he the ideal one for making any one product or class of products, but is designed primarily for plotting in a graphic Tvay the effects which may be obt,ained by substituting varying percentages of pure phenol resinoid in place of other resins in any given standard varnish or paint formula. Khen this preliminary work is completed and curves showing the general trend are obtained, it will doubtless be desirable to concentrate further experimental v,-ork 011 the particular points diicli appear most interesting and work out further improvements in compounding technic.
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Useful Properties of Phenol Resins 7
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The general effects of phenol resins are already familiar to most varnish technologists. but it may be well t o recount them briefly here, DCRABILITY-T~~ outstanding ability of varnishes containing phenol condensation products to ~vithstandsevere weather conditions has been well proved over a period of years. RAPIDDmIsG-L-nlike any other known resin. the phenol resinoids have been found to exert a pon-erful accelerating effect on drying of varnishes and have made possible the preparation of rapid drying varnishes and eiianiels without using excessive quantit'ies of metallic driers and without sacrificing toughness and durability. Although it appears that the effect of the phenol resinoid is to accelerate polymerization rather than oxidation, no satisfactory explanation for this phenomenon has yet been offered, and it is not the
Time and Hardness
great value in coating materials. Unfortunately, however, their use in oil varnishes has long been hampered because none of the c.ommonly known forms of phenol resinoids were soluble in drying oils unless used in conjunction with relatively large proportions of rosin or other similar natural resins. Only recently have distinctly new types of phenol condensation products been developed which are soluble in drying oils m-ithout' the necessity of using rosin or any inactive ingredients to promote solubility. These new resins are available in several different grades, ranging from soft, semi-liquid materials to very hard, high-melting resins. Their color ranges from dark brown up to practically colorless resins. suitable for use in light-colored enamels. All of them, however, are soluble in China wood oil and most of them in linseed oil. The advantage of t,his improvement is apparent as it' makes possible for the first time a quantitative study of the unusual effects exerted by phenol resinoids upon drying oils, without the interfering effects of unkno1Y.n or inactire ingredients. It was thought' that these effects and a discussion of methods of studying and evaluating them would be of interest to those concerned with varnish technology. As the subject is a n extremely broad one, this paper will be limited t o a discussion of one method which Received July 2 6 , 1930. Presented by V. H. Turkington before t h e Division of Paint and Varnish Chemistry a t t h e 79th Meeting of t h e American Chemical Society, Atlanta, Ga., April 7 t o 11, 1930.
Figure 2-Elasticity
(Kauri Reduction Values)
purpose of this paper to attempt to explain it. This is, hoTverer, one of the most important questions before the varnish technologist today and one that is worthy of much thought and work. TocGHsEss--.%khough the phenol resinoids produce varnishes that are quite hard and difficult to scratch or mar, they are also unusually tough and flexible, as shown by
INDUSTRIAL AND ENGINEERING CHEMISTRY
1178
kauri reduction determinations and measurements of film characteristics, such as tensile strength and elasticity. ALKALIRESISTANCE-Even when used in small proportions with drying oils, and particularly with China wood oil, the phenol resinoids have been found to produce coatings which have greatly improved resistance to weak alkalies, soaps, etc. Wherever the coating in service is subjected to frequent or overly enthusiastic cleaning, this property is of great value, as it is claimed on good authority that many coatings are washed away, not worn away.
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the cold finished varnishes are blended, marked improvements are often obtained, though this method is usually considered less reliable. The suggested method may be briefly described in the following steps: (1) Prepare two separate cooks, cook I containing only phenol resinoid as its resin constituent and cook I1 containing no phenol resinoid The resin in cook I1 may be ester gum, rosin, cumar, congo, or almost any well-known varnish gum. I n the specific example on which the data in the present pages is based, the two cooks were made as follows: COOK 1 Pounds Kg. Bakelite XR-254 100 45.4 China wood oil 200 90.7 Lead acetate 6 2.7 Manganese acetate 0.58 0.26
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COOK 11 Pounds Kg. Ester gum 100 45.4 China wood oil 200 90.7 6 2.7 Lead acetate Manganese acetate 0.58 0.26
Cook I was prepared by heating 100 pounds of Bakelite XR-254 with 100 pounds (45.4 kg.) China wood oil to 500" F. (260" C.), adding 100 pounds more of China wood oil and reducing the temperature to 400" F. (204.4" C.). The lead acetate was then added and cooking continued a t 400" F. (204.4" C.) for about 40 to 60 minutes or until the viscosity was almost the same as the normal end point chosen for cook 11. The end point is not particularly critical a t 400" F. (204.4' C.), though cooking should be stopped a little short of the actual end point to allow for some further change during cooling. The
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Figure 3-Durability
WATERPROOFING-The ability of phenol resinoids to resist moisture has always been one of their strong points, and it is not surprising that they impart this quality to oil varnishes to a marked degree. They not only prevent the objectionable whitening characteristic of many natural resins, but also provide films which exert remarkable resistance to the passage of moisture through the film. ACID RESISTAXCE-The phenol resinoids themselves are practically unaffected by most weak acids or their salts, and they impart this quality to drying-oil compositions to a considerable degree, depending, of course, on the relative proportions of resin and oil. M e t h o d of S t u d y i n g Materials
As the practical value of any new material is most clearly determined by comparing it with other materials whose properties and methods of use are already well known, an attempt has been made to evolve a simple and direct method for studying these new resins in comparison with better known materials which would eliminate as much of the cutand-try type of experimentation as possible and enable the varnish technologist to make a few series of simple experiments and obtain a fund of information applicable to many types of products. For convenience this information can best be arranged in the form of curves, similar to those shown herewith, indicating at a glance the effects on any given property of varying percentages of the phenol resinoid. Early in the work on these new oil-soluble phenol resinoids it was discovered that, even when used in relatively small proportions, they exerted an abnormally great effect on the most important qualities of the finished varnish, such as drying time, durability, toughness, and resistance to moisture and alkalies. It was also found that they were well adapted for hot blending with many present standard types of varnish cooks and in many cases capable of imparting improved qualities to such standard materials. Even when
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manganese acetate was added just before the end point was reached. The entire batch was then cooled by water spray on the outside of the kettle. As an alternative, it is possible to check the cook quickly by addition of a little ester gum, rosin or linseed oil, though such additions introduce a variable which is not desirable in this type of comparative experimentation. Cook I1 was prepared by heating 100 pounds of ester gum with 200 pounds of China wood oil rapidly t o 590" F. (310" C.). It was then removed from fire and allowed to cool, driers being added on the way down, first the lead acetate and finally the manganese acetate. The cook should be controlled, by water cooling if necessary, so that time will be available for the blending operation described below. While cook 11 is still hot [400° to 500" F. (204.4' t o ):( C.)] divide it into about ten weighed portions and im260 mediately blend with varying amounts of cook I. Bring each of the blends to approximately the same viscosity, applying further heat where necessary, and then thin with a mixture of 90 parts mineral spirits and 10 parts turpentine. A portion of cook I and cook I1 (unblended) should also be thinned to provide the 100 and 0 per cent samples. Cook I may not be entirely soluble in mineral spirits alone, but may be cleared by addition of a small percentage of solvent naphtha, xylene, or Cellosolve. Small amounts of these thinners may also be required in the blended cooks containing a high percentage of phenol resinoid, though most of the blends will not require any such additions.
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
November, 1930 T a b l e I-Data
1179
on Eight Varnishes, Each C o n t a i n i n g 200 Parts C h i n a W o o d O i l and 100 Parts Total R e s i n , the R e s i n C o n s i s t i n g of Varying P r o p o r t i o n s of B a k e l i t e XR-254 and E s t e r Gum A 1 2 3 5 6 7 8
Sample Bakelite XR-254. per cent Ester gum. per cent Drying time, hours Hardness, 8 hours 24 hours 72 hours Elasticity (kauri reduction) Durability rating" Resistance t o hoiling 5% Ivory soap soln.
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on .. 157
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145 10 Unaffected after 2 hours
Resistance t o 5% N a O H s o h . P r a c t i c a l l y a t 70' F. (21.1' C.) ti n a f f e c t e d after24 hours Resistance t o boiling water: No whiten1 5 minutes i n g ; film hard h ' o whiten1 hour ing; film hard
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19 111 139 70 4 Soft 27 min.; removed 55 min Soft 10 hours; not removed alter 24 hours
No whitening; filmhard No whitening;film hard
Slightly white; Slightly white; White; soft film hard slightly soft White; soft Medium White; soft white; slightly soft
N o whiten- No whitening;filmhard ing; film hard Very slightly Slightly white; white; film slightly soft hard
17 130 152 65 2 Soft 22 min.; removed 44 min. Soft 4 hours: not removed after 24 hours
Discussion of Results The accompanying curves, based on the specific example described above, show the effects of phenol resinoid on drying time and hardness (Figure l), kauri reduction values (Figure 2 ) , durability (Figure 3), and alkali resistance (Figure 4). I n Table I all the data are presented in tabular form, along with results of tests in boiling water. DRYINGTim-The points on the drying-time curve indicate the stage of drying a t which a thin copper foil applied to the surface in strips inch wide and gently rubbed with the finger just fails to adhere. This point is considerably beyond the "set to touch" point as determined by feeling with the finger and corresponds fairly well with the point a t which a second coat could be applied by brush without any difficulty. It is particularly interesting to note the rapid decrease in drying time with relatively small percentages of phenol resinoid, only 10 per cent being sufficient to lower the drying time from 7 l / 2 hours to 3l/2 hours. Beyond this, the drying time decreases a t a slower rate with further increase in the percentage of phenol resinoid, reaching 11/4 hours with 75 per cent and 1 hour with 100 per cent phenol resinoid. HARDNESS-The three hardness curves were obtained by measuring the hardness with the swinging-beam apparatus
18
16 129 159 60 63 1 1 Soft 19 rnin.; Soft 15 min.; removed 35 r e m o v e d 3 0 min. min. S o f t 1 hour: Soft 1 hour; 3 removed 3 removed hours hours
a Figures indicate relative freedom from checks, cracks, o r other signs of failure, 10 being t h e best a n d 1 the poorest. t o November 15 on roof a t 45 degree angle a t Bloomfield, N. J., on maple panels.
We now have a whole series of varnishes differing mainly in the quantities of phenol resinoid and ester gum that each contains. Each one contains the same relative proportions of total resin, oil, and driers. It may be objected that the two cooks are not identical in method of preparation, as the ester gummix mas heated to 590" F. (310" C.) and the phenol resin mix to only 500" F. (260" C.), However, this variation in procedure was considered necessary because of the marked difference in behavior of the two resins on heating with China wood oil. A temperature of 590" F. (310" C.) would have caused jelling of the phenol resin mix, while a temperature of 500' F. (260" C.) would normally be too low to secure a good varnish with the ester gum mix. Before proceeding with tests on the varnishes, it is usually desirable to allow them to stand in completely filled containers for a few days. The varnishes are now ready for whatever practical tests may be desired to show their comparative value for any given use. It is suggested that they be coated out on panels and exposed on the test fence and in accelerated weathering apparatus, where available, to determine durability; also that they be subjected to drying-time, hardness, kauri reduction, water, alkali, and acid tests as well as any other determinations designed to measure their usefulness for any specific purpose.
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Exposure was from June 15
obtained from H. A. Gardner. They shorn the hardness 8 hours, 24 hours, and 72 hours after application. These curves, when considered in relation to the kauri reduction values in Figure 2 , indicate quite clearly that the increased hardness obtained with phenol resinoid is not accompanied by any decrease in flexibility or toughness, quite the contrary being indicated. KAURIREDUCTION VALUES-The kauri reduction values in Figure 2 represent the percentage of standard kauri gum addition which was necessary to produce fine cracks in each of the varnishes on baking 5 hours a t 95' C., cooling to room temperature and bending around a rod 3 mm. in diameter. h'ote the extraordinarily high values obtained with the straight phenol-resinoid varnish as compared with the straight ester-gum sample. I n this case the curve more nearly approximates a straight line, the straight ester gum varnish just failing with a 60 per cent kauri addition while the straight phenol resinoid varnish passed a 125 per cent'addition and just failed with a 145 per cent addition. DURABILITY-The curve showing durability (Figure 3) was obtained by coating the varnishes on maple panels (three coats) and exposing for 5 months (June 15 to November 15) on the roof a t an angle of 45 degrees and facing south a t Bloomfield, N. J. They were then rated by three observers as to general appearance, loss of gloss, and number of checks per square inch, and given arbitrary rating numbers from 1 to 10, 1 being the poorest and 10 the best. The superior durability of the varnishes containing phenol resinoid is clearly indicated. Here again the improvement obtained with small percentages was quite marked. ALKALIREsIsTAm!E-The curves showing alkali resistance (Figure 4) were obtained by coating the varnishes on two sets of tin-plated panels and allowing them to dry a t room temperature 48 hours. One set was then immersed in 5 per cent sodium hydroxide a t 70" F. (21.1" C.) and the second set in boiling 5 per cent Ivory soap solution. The points on the curves show the time in minutes required to soften the film to such an extent that it could be easily removed by rubbing lightly with the back of the finger nail. These curves show clearly that a remarkable improvement in alkali resistance is caused by the substitution of phenol resinoid in a varnish of this type. The varnishes containing 50 per cent or more of phenol resinoid were practically unaffected after 2 hours in boiling 5 per cent Ivory soap solution and after 24 hours in 5 per cent sodium hydroxide a t 70" F. Application to Other Varnishes
It will be realized, of course, that when this method of investigation is applied to other types of varnishes than the
ILYDUXTRIALA N D EiVGINEERILVG CHEMISTRY
1180
one described, the curves obtained will doubtless show different slopes and under some conditions may assume quite different shapes. However, if they provide data indicating the general trend of effects for any given combination in
Vol. 22, No. 11
which phenol resinoid is included as the principal variable, they will hare served the purpose for u-hich the method was designed, and it is hoped may lead to a more complete understanding of the various factors involved.
Physical Characteristics and Commercial Possibilities of Chlorinated Diphenyl'tz Chester H. Penning COMMERCIAL RESEARCH DEPARTMENT, SWANW RESEARCH, INC., AWNISTOW, ALA
The physical properties of 2- and 4-chlorodiphenyl OLLOTT'ISG the anits viscosity is 30 seconds and their eutectic mixture are given, together with the n o u n c e m e n t of the Saybolt a t 210" F. (99" C.) ; physical characteristics of reproducible mixtures of successful production it has a flash point of 127more highly chlorinated isomers, which vary in conof diphenyl in commercial 129" C. and a fire point 50 sistency from that of a light mobile oil through a thick quantities a t a reasonable degrees higher. sirupy stage to a solid resinous or crystalline state. price, the manufacturer of T h e monochlorodiphenyl This is followed by a discussion of the commercial this new chemical mas delmixture first obtained conpossibilities suggested by the properties of the comuged with suggestions for the tains about 19 per cent by pounds, including use in varnish and lacquer, watersynthesis of new compounds weight of chlorine, and is a proofing, flameproofing, electrical insulation, etc. using diphenyl as a base, liquid having practically the and with requests for quoviscosity of water. As chlotations on various diphenyl derivatiyes. Many of these rination proceeds the visible effect of the higher chlorine conshon-ed a lack of understanding of the nature of a true di- tent is an increase in viscosity. This increase is gradual up to phenyl compound, so that it is considered worth while, before 40 per cent chlorine and then very rapid, as shown in Figure 1. discussing these products, to mention briefly the system used A series of products is thus obtained which varies in consistin naming them. Most of the so-called "diphenyl" com- ency from that of a light mobile oil through a thick sirupy stage pounds now on the market do not contain the true diphenyl to a solid resinous or crystalline state. These products are begrouping. This may be illustrated by structural diagrams ing marketed under the trade name "Aroclor." The Xroclors showing, for example, the well-known compound diphenyl- are not in all cases pure chemical compounds; their peculiar amine and the corresponding true diphenyl compound, amino- physical properties are probably due in large part to the fact diphenyl : that they are mixtures of various isomers. By careful control of the chlorination and subsequent operations these mixD - C > H 2 tures can readily be duplicated both physically and chemiDiphenylamine Aminodiphenyl cally. Table I shows how some of the other physical properties The true diphenyl compound contains two phenyl (CsH,) vary d h the degree of chlorination. Aroclors 1219, 1242, groups directly connected to each other, 1%-hilethe di-phenyl 1254, 1262, and 1268, representing increasing percentages of compounds contain two phenyI groups not directly connected. chlorine, are taken for comparison. The color changes from I n designating the positions of various substituted radicals water-white to a light amber, The melting and boiling in true diphenyl compounds, numbering begins at the linkage, points rise, as does, of course, the specific gravity. The flash as shown: point is raised, also the fire point; Aroclors 1262 and 1268 will not take fire below their boiling points. Other physical characteristics, not indicated in Table I, 5 0 6 5' may be described briefly. Aroclor 1219 has a very distincWhen technical diphenyl (98.5 per cent) is chlorinated under tive, though not unpleasant, odor; the other products are certain conditions of control, as previously described by practically odorless, and tasteless as well. They have no Jenkins, McCullough, and Booth ( I ) , a mixture of the 2- and 4- noticeable action upon the skin; the concentrated vapors are monochloro isomers is first obtained. The pure P-chlorodi- irritating to the nasal passages, and cause violent headaches phenyl is a white crystalline product (monoclinic prisms) to certain persons, but aside from this no toxic effects have melting a t 32.2" C. and boiling a t 273.7" C., while the 4- been noted. All the products are stable on prolonged heatchloro derivative crystallizes as flat orthorhombic plates melt- ing at 150" C. The oils may be distilled a t atmospheric ing a t 77.2" C. and boiling a t 291.2" C. A eutectic mixture of pressure without appreciable decomposition and the resins the two, containing 3 parts of 2-chlorodiphenyl and 1 part can be distilled under vacuum. Boiling 10 per cent caustic of 4-chlorodiphenyl, melts at 14" C. and boils a t 278" to soda solution has no effect upon them. The Xroclor oils are non-drying; they undergo no appreci295" C. This mixture, being liquid through a Fide temperature range, exhibits marked solvent properties, and is able oxidation or hardening on exposure to air. Similarly, itself soluble in or miscible with a large number of organic the Aroclor resins are apparently permanently thermoplastic. liquids. It has a specific gravity at 25"/25" C. of 1.1567; They undergo no further condensation or hardening on repeated melting and cooling, so far as experiments have been 1 Received September 1.5, 1930. Presented before t h e Division of carried. They are being produced with softening points Industrial and Engineering Chemistry a t t h e 80th Meeting of t h e American between 70" and 75" C., as measured by the A. S. T. M. test Chemical Society, Cincinnati, Ohio, September S t o 11, 1930. for asphalts and pitches; by certain modifications the soften2 Contribution Pio. 4 f r o m t h e Laboratories of Swann Research, Inc., ing point can be changed considerably. Anniston, Ala.
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