October 1951
INDUSTRIAL AND ENGINEERING CHEMISTRY
(183) Shur, Ya. S.,and Vlasov, K. B., J. Inst. Metals & Metall. Abs., 18,Part 2,98 (1950). (184)Simpson, R. T., and Sawyer, W. T., Mech. Eng., 72, No. 9, 712-16 (1950). (185) Skinner, E. N.,and Kozlik, R. A,, Combustion, 22, No. 6, (1950). (188)Soap, Perfumery, & Cosmetics, 23,No.4,383-8 (1950). (187) Spencer, L.E., Iron A g e , 167,No.9,105-9 (1951). (188)Stanworth, J. E.,J. Sci.Instruments, 27,282-4 (1950). (189) Steel, 128,No.10,86 (1951). (190) Ibid., NO.14,pp. 81-3. (191) Stocker, W. M., Machinist, 94,711-26(1950). (192)Street, R.,and Woolley, J. C., Proc. Phys. Soc., 68, Sect. B, 509-19 (1950). (193) Sully, A.H., Nature, 167,No.4244,385-8(1951). (194)Sussman, H.,and Ehrlich, S. L., J. Acoustical SOC.Am., 22, 499-506 (1960). (196) Swenson, 0. E.,Welding S., 29,No.12,1053-8 (1950). (196) Taglang, P., Compt. rend., 229,No.15,704-8 (1949). (197) Taylor, A.,J . Inst. Metuls, 77,Part 6 , 585-94 (1950). (198) Teeple, H.O.,Chem. Eng., 57,No.9,212,214-17(1950). (199) Teeple, H.O.,IND.ENO.CHEM.,42, 1900-2001 (1950). (200) Teeple, H.O.,Paper Trade J . , 131,No.19,28,30-2(1950). (201) Thien-Chi, N’G,Ann. RadioelectricitB,5,339-53 (1950). (202)Thien-Chi, N’G,and Michel, B., Ibid., 6,No. 23,3-19 (1951). (203) Thurnauer, H.,Eler. Mfg., 47,No.3,82-5,230,232 (1951). (204) Thurston, R. T., and ‘CT’ulff,J., Welding J., 29, No. 7, 313s19s (1950). (205) Trans. Inst. Welding, 13, No. 4,79r-80r (1950). (208) Treat, R. M., as told to Chase, H., Stesl, 127, No. 17, 88-70 (1 950). (207) Unckel, A. H., sheet Metal Ind., 27,No.279,654-8 (1950).
(_______--
(208)U.8. Air Force, Air Mat. Command, Tech. Rept. 3712 (1948). (209) Veeder, M.N.,Fasteners, 7,No. 1, 7-10 (1951). (210) Vidal, G.,and Lescop, P., Rev. gBn. mbcanipe, 34,170 (1950). (211) Vuilleumier, C., Von Roll Mitteilungen, 9,65-96 (1950). (212)Wache, X.,MBtauz et Corrosion, 25,267-76 (1950). (213)Watson, T. T., and Rothermel, R. R., Welding J., 30, No. 3, 118-122 (1951). (214) Weisert,E.D.,Chem. Eng., 58,No.4,218 (1951). (215) Welding J.,29,No.9,808(1950). (216) Wernick, S., Metallurgia, 42,No.253,339-44 (1950). (217) Wheeler, H.L.,Jr., and Duwez, P., Automotive Ind., 103, No. 2,40,110,112 (1950). (218)Whitaker, G.C.,Corrosion, 6,No. 9,283-5 (1950). (219)Whitaker. M., Sheet MetaZInd., 27,No.281,815-24 (1950). (220) Wilkes, G. B., Jr., A m . SOC.Testing Materials, Spec. Tech. Pub. 108,ll(1950). (221) Wilson, H.W., Phys. Rev.,79,1032-3 (1950). (222)Wilson, R.M., Jr., Welding J.,30,No. 3,247-56 (1951). (223)Wolfe, K. J. B., and Spear, P., Aircraft Production, 13,No. 149, 80-83; NO.150,117-20(1951). (224) Woodard, P. H., J. FrankZin Inst., 249,493-4 (1950). (225) Wylie, T. S.,J. Roy. Tech. College, Glasgow, 5,6-25 (1950). (226) Yamamoto, M., and Iwata, T., Phys, Rev., 81,887-8 (1951). (227) Yang, L.,J. Electrochem. Soc., 97,No.8,241-4 (1950). (228) Young, L. J., and Bauld, R. H., BIOS Final Report, 1003 (1947). (229)Zimmerman, E.N., Welding Enpr., 36,No. 4,34-5,39 (1951). (230) Zimmerman, J., Bull. Am. Phys. Soc., 26,No. 2, 13 (1951). (231)2.Metalllcunde, 41,2834 (1950). RF.CEIVED August 22, 1951.
PAINT
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I . -
JOHN C. MOORE,
2251
National Paint, Varnish,
and Lacquer Association, Inc., Washington, D. C.
producing the advantage of thicker coats, saving of solvents, and absence of fire hazard. Polyvinyl chloride dispersions are recommended for this purpose (66). Polyvinyl chloride films plasticized with dibutyl sebacate and dioctyl phthalate were very susceptible to mold attack, whereas those plasticized with dioctyl phthalate or butadiene-acrylonitrile were inert to fungus or mold growth. The changes in tensile strength and percentage elongation may be used as a criterion for measuring the degradation of films containing mold-susceptible plasticizers (IO). It iR sometimes difficult to determine whether the dkoloration of certain paints is caused by mildew or dirt. A survey of houses in need of repainting diaclosed that 6301, were discolored by mildew, 37% by dirt. It was necessary to use high magnification and culture tests to produce this technical information. Evaluation by the naked eye was insufficient (8%). The painting of breweries presents a n unusual combination of high humidity, high and low temperatures, marring and abrasion, and action of yeast, beer, soaps, detergents, and mildew. A styrene-butadiene copolymer is used to produce a satisfactory paint for breweries. Mildew does not seem to grow on this type of paint under the conditions existing in a brewery (31). The effect of various types of chemical fumes on the selection of the proper protective coatings has received consideration for many years. Laboratory-accelerated tests permit screening of large numbers of paints, but field tests on moderate-size panels and on equipment are etlsential to final evaluation. Laboratory tests can be used for evaluating the integrity of the film itself, but field tests are needed to determine the protection given by the
‘rechdcal progress in the paiiit industry is accelerating. Many new raw materials have become available during the past year, and these have made possible production of improved paints in general. This article briefly describes each new product as well as some new testing procedures.
T
HE ingenuity of the paint formulator, the availability of new raw materials, and the knowledge that the paint industry is a large potential purchaser of such products have stimulated additional research which produces paints of increasingly high quality. New uses for paints, and the desire for improving the utility, place a demand on the formulator to produce new and better products. Radioactive contamination has resulted in a systematic attempt to develop simple tests permitting the comparison among various coated surfaces, decontamination reagents, and contaminating conditions. The term “decontamination reagents” L defined as: D.I. = log (activity on surface before decontamination/activity on surface after decontamination). This is proposed m a measure of the degree of removal of air-dried radioisotopes as contamination from surfaces (64). The susceptibility of various paints, plastics, and floor materials to contamination and their subsequent ease of decontamination have been determined by simple empirical tests. The degree of decontamination possible on many surfaces is reduced to numerical terms and the efficiency of approximately twenty commercial detergents in decontaminating Lucite and various selected resins is tabulated (86). Certain resins disperard in ~1 liquid may form a gel a t elevated temperatures. Dispersion of a resin in a plasticizer may be heated, causing the absorption of the plasticizer by the resin, and
2252
INDUSTRIAL AND ENGINEERING CHEMISTRY
paint. Rubber-base paints have found aide utility as fume-resistant coatings (25). Bpplication of protective coatings to a % e tsurface is said to be made possible by adding up to 10% or organic substituted alkylol amine to oleoresinous varnish; this increases the water tolerance of the varnish. These amines must boil between 250” and 500’ F. and have the general structure HOR-N-R’(R’’), where R is an aliphatic hydrocarbon group of 1 to 5 atoms, R’ is a member of the class consisting of hydrogen and alkyl radicals, having up to 8 carbon atoms, and R ” is an alkyl radical having up to 8 carbon atoms. This patent suggests that wet surfaces may be painted with many types of coatings which contain this organic substituted alkylol amine (60). Silicone resim have found use in the manufacture of special paints, particularly those of the heat-resistant type. Some silicone resins are thermosetting polymers. I n the unpigmented form they have found use in coating baking tins so as to eliminate the necessity of greasing them; it is said that a single coat lasts for 200 or more bakes in the bread-making industry ( 5 ) . The combination of paint with cathodic protection of sufficient magnitude materially aids in the prevention of corrosion on marine vessels, and for oil drilling equipment used in the presence of salt water, such as that required for drilling operations on the continental shelf (14). The superstructure of oil drilling platforms over salt water presents a difficult problem for corrosion engineers. Two coats of zinc chromate-phenolic-type paint covered by a black phenolic coating, then covered with a rustinhibitive coating of zinc dust-zinc oxide type paint, are said to give adequate protection (44). Extensive laboratory and field tests mere, of course, necessary to produce the desired information; such tests as water vapor transmission of films, adhesion, 20% salt spray resistance, and flexibility were essential to the selection of proper coatings (4). One method for evaluating the active protection by pigments in paint for marine use was determination of the difference between the electrode potential against sea water of a painted and an unpainted iron plate. The plates were painted in stripes, so that portions of unprotected iron were in contact with the sea water. Microscopic examination of the corroded surfaces and determination of potentials afford a useful supplementary test for the protective value of a paint, but are not reliable as a sole test of such coatings. This is only for laboratory use (29).
ASTIFOULING PAINTS
Improved antifouling paints depend on the leaching quality of the poisons normally included in such paints, and such leaching must be controlled to produce a very slow action. The role of rosin substitutes in antifouling paints has been evaluated. With the advent of tall oil in commercial quantities, tall oil esters of glycerol and pentaerythritol were compared with abietic acid as a rosin diluent. The esters appear to affect antifouling efficiency and physical durability adversely in direct ratio to the extent to which they are substituted. Abietic acid and hydrogenated methyl abietate perceptibly improve the physical properties of the film. Tall oil may be substituted for rosin up to 50% without affecting the performance of the paint. A copper pigment containing essentially 85% copper and 15% cuprous oxide does not equal cuprous oxide as an antifouling pigment (1). It is claimed that a paint using a cement-copper ground to pigment size imparts superior antifouling properties to marine paint. The copper is said to leach from such paint many times faster than similar paint containing all its copper in the form of cuprous oxide ($7). A patent for antifouling paint includes a claim that organometal perthiocyanates are fungicidal and antifouling pigments. Most of the examples cite some form of mercury in the formula, but claims of the patent cover compounds in general, several
Vol. 43, No. 10
alkyl niercury compounds, and antifouling paints containing the compounds (25). A coating of improved weathering properties for metal is formed by mixing an oil-soluble heat-hardening phenol-formaldehyde resin with polymerized styrene and terpene resins in a mixture of aromatic and aliphatic hydrocarbon solvents. This coating ie supposed to protect the metal from the weather (18). Calcium plumbate is stated to be a new paint pigment which will inhibit corrosion. Practical tests of paints using this pigment indicate unusual resistance to blistering and rust creep, when immersed in salt water. Adhesion to galvanized iron is said to be good (62). FIRE-RETARDANT PAINTS
-4 “puffing” type of resin-phosphate fire-retarding coating is said to form an insulating mat when it is exposed to a hot flame, which stops heat from penetrating to the flammable surface underneath, and a t the same time halts flame spread, as there is no fuel to burn (66). A three-component mixture consisting of a protein, a foamforming ingredient such as monoammonium phosphate, and a resinous binder such as urea-formaldehyde, is claimed to produce a coherent carbonaceous foam of a fine texture. This mixture, when suspended in either an aqueous or nonaqueous paint vehicle, such as one containing dehydrated castor oil, gloss oil, and a drier, is said to produce superior fire-retardant compositions (50)
Certain titanium compounds are said to confer fire-retardant qualities on textiles, paints, ceramics, and building compositions. Addition of antimony oxide seems to confer flame- and glow-retardant properties on titanium compounds. The information developed to date indicates that use in coatings should produce good fire-retardant properties on fabrics (45). Improved heat-resistant coatings are said to be made by including boric acid-lead compounds, mixed with methyl silicone resins; drying oils and various oleoresinous varnishes may be included (71). A coating of anhydrous lead metaborate, organic binder, pigment, and thinner is claimed to produce a superior composition for hot surfaces, such as smoke stacks and exhaust pipes. Lead metaborate is usually present in excess of the amount of binder used (2). A heat-resistant paint consists of a nonleafing aluminum flake pigment, dispersed in a colloidal silica solution, such as alkyl silicate. Improved stability of the dispersion may result if pigment is pretreated with an alkyl partial ester of phosphoric acid, such as methyl phosphoric acid (63). Butyl titanate combined with aluminum powder has shoxn promise as a heat-resistant paint under very severe test conditions-Le., the interior of steel stacks, subject to hot corrosive flue gases, showed no signs of deterioration after 32 weeks of exposure (60). The use of fluorescent and luminous paints has sometimes been held back because of the effect of sunlight and air. A thermohardening composition applied over such paints would improve their life. It has been found that certain plasticizers accelerate the decomposition of certain fluorescent material and must be omitted from contact n-ith the dye or pigment. Patent claims cover plastic materials, but the examples cite thermosetting alcohol-modified urea-formaldehyde (61). Daylight fluorescent pigment has been developed which reflects more light of a given color than is present in the visible light the pigment receives. The preferred way to obtain daylight fluorescence is to dissolve a certain dye in a thermosetting resin, grind the resin to pigment size, and use this material as the pigment in a paint. Best results require that the refractive index of the vehicle be the same as that of the pigment. Paints must exhibit no milkiness and dye must be present in the pigment in cer-
October 1951
INDUSTRIAL AND ENGINEERING CHEMISTRY
tain limited percentages. The patent covers the pigment, in paint, and displays making use of the pigment and paint. The same pigment may be incorporated into plastic compositions for forming into sheets. These products are normally found in displays (daylight) and signs (68). Today the silk screen process for applying color plays an important part in many industries. Improved methods of application use certain machinery to make superior stencils which sometimes look as well as the handpainted articles (11). Among the most promising new paints recently developed axe those based on the copolymers of styrene and butadiene. These paints, although formulated for interior use, are said to give good exterior service. Latex emulsion paints of this type are being more widely used; the nature of such products may be changed by the different percentages of styrene and butadiene in the latex (18). Improved pigments are being produced by the jet-mill method of grind. The size of the pigment is regulated by the rate of feeding the pigment into the mill. Oil absorption may be lowered, wetting and dispersion become easier, and tinting strength is raised. Moisture is often eliminated, and if the pigment is packed in sealed, plastic liners, may be delivered dry to the paint mill. The use of jet-milled pigments promises superior pigments for the paint manufacturer (39). SYNTHETIC RESINS
The use of synthetic resins by the paint industry has been on the increase for many years, but 1950 is additional proof that the paint industry is turning more and more to synthetics. For the first time in many years, phenolics were replaced by vinyls as the largest-volume synthetic. The tremendous increase in the use of synthetics since the end of World War I1 is positive proof that the paint chemist, in his desire to produce superior products, knows where to go for the proper raw materials (13). One of the more prominent new synthetic materials is the styrenated alkyds. Introduced to the industry only two years ago, they are already finding their place in low cost, fast-drying enamels, in baking undercoats, and in air-drying undercoats. The importance of these fast-drying alkyds is realized by the Armed Forces, as some of their new paint specifications are based on the use of styrenated alkyd resins. They prevent delays in the production line (46). A conventional composition for decorating still-wet insulation board is made with starch and pigments. The addition of tributyl phosphate to the composition makes it dry to a uniform appearance (37). One of the objectionable characteristics of many brushing lacquers is the bleeding tendency when the old lacquer finish is recoated. The old application starts to dissolve in the solvent of the applied lacquer and when different colors are used an unsightly streaky appearance results. Incorporation of a resin modified with a fatty acid results in a coating which because of oxidation and polymerization becomes insoluble to successive coats applied later. The ratio of resin to cotton should be more than 1 to 1 (38). LIGHT- FASTN E S S
Dyed aluminum powder resembles ordinary aluminum powder in shape, structure, and particle-size distribution, but differs from it in having a colored surface. This combination of color and metallic luster distinguishes colored aluminum powder both from plain aluminum powder and from the typical colored inorganic pigment and the pigment dyestuffs. The difference is due to the limited stability to sunlight of the dyestuffs available, which normally precludes the use of dyed metal powders in paint intended for outdoor use,and to the fact that dyed metal powders do not leaf (68). Colored metallic powders, even more than
2253
natural copper and gold bronze powders, must be considered as purely decorative pigments. The light-fastness of an azoic pigment from tetrazotized dianisidine and the o-phenetidide of 2,3-hydroxynaphthoic acid, may be increased by heating the pigment in an aqueous medium to a temperature above 100" C., and heating below the deconiposition temperature of the pigment until the pigment has been transformed into a physical form having a greatly enhanced lightfastness and characterized by an x-ray diffraction pattern with lines of greatest and next greatest intensity a t interplanar spacings of 13.3 and 3.34 A., respectively (49). Phthalocyanine pigments are rendered nonflocculating by mixing them with their monosulfonic acid derivatives or alkali earth salts thereof. From 5 to 80% of the sulfonated pigment is used, except in nitrocellulose lacquer where over 40% may tend to gel the lacquer. The patent also claims paints made with the nonflocculating phthalocyanine (80). The light resistance of polyvinyl chlorides is improved by the addition of 0.1 to 10 parts per 1000 parts (by weight) of an alkali metal bichromate (40). A coating composition for flexible surfaces consists of (1)polyvinyl butyral; (2) a copolymer consisting of styrene and the copolymerization product of a secondary alkyl half-ester of an ethylene a,p-dicarboxylic acid such as maleic or fumaric acid, wherein the alkyl radical contains from 6 to 10 carbon atoms, the half-ester and styrene being copolymerized in a molal ratio between l to l and l to 2; and (3) a plasticizer for film-forming materials (3). A new resinous polymeric material is made by reaction of eirconium n-butylate and trihexyl phosphate a t a temperature above 120" C.; thereaction is continued until a t least 40% of the organic radicals in both reactants have been replaced (34). The dimer obtained from butadiene or piperylene is a watery liquid which can be polymerized t o a hard brittle resin of low impact strength, If one of these dimers is heated with about 25% by weight of drying oil, a resin is obtained which yields hard, flexible varnishes. Examples cited include tung, dehydrated castor, linseed, and oiticica oils. The properties of the resin may be varied by changing the oil and by varying the proportion of oil between 5 and 50% (81). Castor oil is continuously dehydrated by flowing in a thin film over a surface heated to 350' C., in a vacuum. Sulfuric acid is used as the catalyst (51). A catalyst made by reducing a mixture of nickel silicate and nickel sulfate is particularly effective for inducing conjugation in nonconjugated oils (59). The composition and uses of temperature-indicating paints are interesting, The pigment Cuz(HgI1) is bright red below 55", deeper red from 55' to 60°, chocolate from 60" to 70", gray between 70" and 91", and black above 91°C. It isprepared by precipitation from mrtrcuric chloride (271 grams), sodium iodide (900 grams), and oopper sulfate (250 grams) in aqueous solution. Agz(Hg14),also prepared by precipitation, is yellow below 45", orange between 45" and 50°, and pale red above 50'. The pigments are best made up into paints with a medium of polystyrene (100 grams), tricresyl phosphate (20 ml.), toluene (40 ml.), and xylene (500 ml.), using 100 grams of pigment to 250 ml. of medium. Aluminum is attacked by the paints (38). Extensive tests conducted to formulate the best paint systems for protecting and decorating the Dow plant a t Freeport, Tex., permit some conclusions to be drawn a t the end of 3 years. In addition t o protecting steel and other materials, maintenance of color (vermilion, blue-green, light gray, black, white) was considered of almost equal importance. A system made of primer A (red lead, zinc yellow, zinc oxide, iron oxide, magnesium silicate, and diatomaceous silica in fast-drying synthetic varnish) and finish M (medium oil butyl phenolic resin varnish appropriately pigmented) is claimed to give the best results. Experiments on suitable pigment combinations for best color retention and eight
2254
INDUSTRIAL A N D ENGINEERING CHEMISTRY
types of exposure condition:: that prevail at. the test location are discussed (67). .\nether new resin tliat, is finding wide usage is Epon---condeiimtion IYilymers ccritainin~units o f epoxide and bisphenol. They are cornpatihle with cik arid other resins, scluble in selrxtetl solveiits, and can be usi4 i ] ~furmulatirig air-drying and h a k d enamels (43). A coniniercial tall oil coritninirig 87% i,osin acids was esterified by glycerol, pentaeryt,liritol, aorbitcl-pentaerythii~l (S0--20), poiyallyl alcohol, and Epon 1004. It is claimed that the Epou ester had the Lest visccsity! color, alkali and Rater resistance, hardnees, d r l i n g rate, a~itf outdoor durability. Bc dying of the other esters a t high v:tr.rii:'h-iii:ikirlR temperatures led to darkening, and except in the cafie of pc~itaerythritclto excessive acidity. Maleic modification imp1 1 tht. properties of the straight Eporl tailate attained, and m:tlcic-iii~rtiifiedpciyallyl tallrite was best in this regard. Esters of t d l oil containing 18% rcsin had the vkcosity, drying rate, anti iiiidness typical of varnishes only iu the case of Epon. Wit1 reasing rosin content ( 5 to 64%) of h c i w e t l a. trend toward faster surfactl tall oil, derived Epon est drying, greater hardness, 1 ~ flexibility, s and poorer resistance to boiling water. Within the rno& comnion range o f rcsin content (37 to 48%), individual diffcrenccs among tall oil esters exceeded general trends related LO r o h content, (63).
VoJ. 43, No. 10
The styrenated resins have a drawback in their lack of resistance to petroleum thinncrfl. Interpolymers c l from 50 to 60 weight % cf combined styiene in polymer fcrni, a t o u t 30Oj, of combined acrylonitrile in polymeric fcrm, and from 20 to 10 weight % cf combined butadiene in polyrnciic form produce coatings o f excellent I fsistancc to petroleum naphf ha, hensene, etc. (67). ZIct spray nlleri compared to cold spray effects savings i l l oveispray, thinner, and labcr. One of the major difficulties which has recently been overcome is the devclopmrnt of an efficient, safe, arid practical heating unit (,hicf bugi in this mechanism, now solved, were the bnelling of ( lubrication of the shaft seal, ~ n ad slow speed Field tests claim to horn that one coat et ronvtwtional znir dust paint gives gocct prLtection to galvanized iion rcots if 1cose bcale is ienioved vlith a btiff brush. Conventional Tin, dust paint contains 80 paits of zinc dust and 20 parts of zinc ( xide in a vehicle o f linseed or soybean oil. The paint weighs about 23 pounds per gallon, Extra labor for wiicx hrushing is not rewarded by extra duxability (48). Oil-soluble quaternary ammonium conipounds, such ab alkyl dimethyl benzyl arnnionium naphthenates, are soluble in linseed oil, synthetic rwinu, and the common paint solvents. They may 1x3 used as fungicides and to protect casein paints fioni bartri ial decoinpcsition (42). Urea-formaldehyde resins of ~t high tolerance to naphtha ai e 51'1 I \ S I X 80LVEN1'S formed by condensing 2 moles of formaldehyde with 1 mole of Urie problem in the u~ of \ iuyl iLsiris is finding a suitable solurea in butyl alcohol until water ceases to be evolwd, adding 0.5 vent. The use of cyclohexanc~nc~ is limited by cost; the iibe of ii to 3 moles of aldehyde, and again condensing until no more throe-component solveiit gives a higher solvency value fool the water is evolved (17). Jaiiie cost. The rangts ol each component is 37 to 65% cyclic The difficulty of finding a suitable solvent foi polyacrylonitrile ketone, 10 to 50% aliphtitic kctonc, and 8 to 30% toluene ($4). has limited its use. Solutions of polyacrylonitrile can fie ob. -4 mixture of pigment and 1 ebin is prepared by grinding the tained using a binary mixture of 60 t o 80% by volurne of nitropigment, resin, and a %:iter-inisciblc Holvent for the iesin iii n ball methane and a-hydi oxypropionitrile as a solvent (16). mill, and when solution o l the r(ibiIi is complete, adding water to A wrinklefinish varnish i R essentially a polyester made with precipitate the resin untl the pigment. The precipitate is then carbic anhydride and an alkyd. An important feature is that dried and ground to a ponder. In this state, it niaj be u ~ t (dJ the baking opeiation to produce the wrinkling may he delayed for tint paints. The method avoids the usual hazard of coating 0.5 hour or nicie without affecting the texture. The patent pigiiient with resin (288). claims cover both the method of preparing the varnihh a n d the The heat polymers of 101s rr,olecular weight recoveied from final dry finish (36). petioleum stills when heated to a temperature of above 150' C:. The higher unsaturated fatty acids are capable of combining in the presence of boron t i ifiuoride catalyst are converted to %ith aliphatic dianiides to form diamides with acid radirals. thermoplastic resins suitalilc lor vtu nishes. The resins have it These diamides, pollnir~iize like the drying oils, through either melting p i n t o f 70" to 200" C'. and an iodine number t i f 200 to autoxypclymerization < r t tiermitl polymerization. Jlence, thii 340 (54). group of mateiials can be used as film formerr;. They are wluble The cojoint crystal ( ~ paittfhii f and polyethylene is R w a x with in the commonly used solvcnt6, and the dried films shon excrllent properties siniilar to those of carnauba wax. The cojcint ciystrtl 1 esistarice to alkalies and acids. The ai tick discusses the is formed by heating the p . ~ i n f f i r i WBZI (19 to 91%) slowly to preparation and the propel ties of dimethyl dist~aramide,dilinol320' E., viyoi ously agitating until no t q s t a l s of pclyethyleiie 0 1 rtmide, and diclcostearainide (13) paraffin are ol)c;cived,jxmring into molds, and corling (35) The copolymerization ot 2-rhlo10allyl Iiiiol~atewith styr ene strippable coating picyiai i d fr ~111133 to 67% pols i i i r r i ~ t d was studied, in bulk, using benzoyl peroxide, stannic chlrrid(~,and ethyl niethaciylate, 33 to 4 1% nioiionmic acyl amidt , 8 to 20% potassium persulfate a8 catalyst Self-pol> mv1ization of the lanoliii, and 2 to 10% j h t i c i r t ~ r ,cm be applied in x nieitetf lirioleate did not occui n.heii benzol1 prrrxitle n:is used. Cocondition at about 150"
