EPOXY
i
RESINS
The union of bisphenol A and epichlorohydrin spawned a giant. The young, healthy offspring, originally intended as an answer to industrial coating problems now appears headed for bigger and better things. Although epoxides were invented i n the 19th century, they remained laboratory curiosities until Shell Chemical made its epichlorohydrin commercially available. Jones-Dabney i n the U. S. and Ciba in Switzerland introduced experimental expoy resins around 1945; JonesDabney directed its efforts into making surface coating products, Ciba, making nonsurface coatings. In less than a year, Shell entered the picture with a formula based on the bisphenol A-epichlorohydrin condensation process and the future of epoxies was assured. In this day of diversification, it is not surprising that the original combination of chemicals has gone by the board. Epoxy resins are now prepared from a wide variety of chemicals with bisphenol A still b y and large the anchor
compound. A solid vote of confidence that it will remain so can be found in the existing and projected plant capacity for bisphenol A. Shell Chemical, Dow Chemical, and Monsanto can now turn out a combined volume given as 70 million pounds per year. By 1961, they will be able to turn out an additional 45 million pounds per year bisphenol A, with Union Carbide Plastics joining the trio. Epoxy resin capacity is ample. It i s rated at 104 million pounds per year now, with Shell, Ciba, Union Carbide, Borden, DOW, Reichhold, and Jones-Dabney contributing to the total. Estimated production for 1965 runs only around 90 million pounds per year. The price structure of epoxy resins i s as widespread as are their formulations and uses. On the l o w end, prices for the dry forms range from 31 to 33 cents per pound, the highs range from 50 cents to $1.15. liquids or solutions range from a l o w of 323/4cents per pound to a high of $1.40, based on resin content.
Forecasting Epoxy Resin Markets
ANY discussion of epoxies brings out one conclusion-they have been excep-
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P
tional. From the first, the bisphenol A-epichlorohydrin formulations have been growing at a remarkable rate both from the standpoint of changes in base formulation and the range of application. A projection of the possible yearly consumption in 1966 must consider these changes as well as the many new possible, and in some cases probable, uses that have been suggested. One of the most baffling factors in preparing a projected usage is the wide variety of estimates from many sources that can be developed. Double counting by the Tariff Commission, rapid inventory build-ups, and relatively large captive uses have all tended to preclude accurate pinpointing of consumption figures. This is especially true for individual end-use applications. Again, the very definition of the epoxy group has been changed such that an epoxy may no longer be a bisphenol A-epichlorohydrin combination but is now
and probably will be a modified form with either new materials for the polymer itself or with variations of the hardner. Properly, these modifications should be considered in any projection of consumption. Estimating Basis
The past growth of epoxy resins has been rapid. I n analyzing this, it is the total dollar sales which are indicative, not poundage sales. Their relatively high price and relatively high consumption places them in a class with nylon, poly(viny1 butyral), and one or two others. A reasonable approach in evaluating past data is to relate epoxies with industrial-type surface coatings, their prime end use. Here some adjustment to published figures is necessary to translate industrial-type coatings into pounds of epoxies in all surface coating applications. A ratio obtained from this relation can then be used to plot growth rate for future and existing uses. Existing Uses
Paint, Plastics, and Printing Ink Chemistry, Symposium on Epoxy Resins, 136th Meeting, ACS, Atlantic City, N. J., September 13-18, 1959.
A good basis for projecting future consumption of existing uses is to pick up known volumes and using the ratio method, arrive at a figure that is reasonable and can be supported. I n sur-
face coating, it is reasonable to project epoxy growth as industrial-type paints, because volume will grow as over-all industrial activity expands. Where these coatings may lose to other types of coatings in one area they are likely to make it up in other areas. Assuming a normal 2 to 3y0 growth per year for industrial coatings, and using the ratio factor for epoxies in these coatings, a projected volume of about 41 million pounds per year for this type of epoxies consumed in total surface coating applications is reasonable. T o support this figure, a projection of the past year’s epoxy consumption by all surface coating applications indicates a 35 to 45 million pound-per-year volume by 1966. There are five main existing surface coating uses for epoxy resins, either straight or modified: auto primers, appliance primers, containers coating, pipeline coatings, and special maintenance coatings. They represent a large portion of the 25 to 30 million pounds of resin consumed for all surface coating end uses in 1959. And epoxy-based coatings are relatively secure in these markets. There are few if any threatening competing materials in these markets. A straight 3% per year growth would raise the volume needed to 30 to 35 million pounds per year by 1966. VOL. 52,
NO.
4
APRIL 1960
317
There Are Five New Uses for Epoxy-Based Materials on the Horizon; Some Are Brand New, Others Developmental Lb. Patching compounds As solder replacement in automobiles and other metal fabricating applications 3-8 million Antislip coatings, depending on evaluations Highway coatings now under study 0-5 million Printed wire finishes Now being used to some extent and likely to expand 0-2 million Currently being explored with some indicaCement block glaze 3-8 million tions of good success M'ill grow with improved methods of applicaFurniture coatings tion 0-3 million Future Uses
The sum of these five areas is 6 to 26 million pounds per year. Added to the 30 to 35 million range for surface coatings a range of 36 to 61 million pounds per year in 1966 is obtained. Similar evaluation of other main uses of epoxies-tooling, laminating, adhe-
sives, encapsulating, and an all-other category-yields a combined requirement of about 45 to 50 million pounds per year. Adding this figure to the coatings applications, considering all categories, a total consumption of epoxies for 1966 of 85 to 95 million pounds per year is obtained. This is almost double the 1959 demand, a growth rate
of over 1Oyo per year. I n comparison, the past growth rate from 1952 to 1959 was slightly under 40% per year. Two additional factors must be considered in support of the projected volume-price of epoxies will continue to decrease as the number of basic producers in the field increases; and new ways of application promise future economies. Assuming lowering prices, changing raw materials and improved applications methods, epoxies will continue to expand. By 1966 about 85 to 95 million pounds, worth slightly less than $50 million, should be consumed. Paint markets will continue to be the large end use.
J. R. WlLLNERl
Roger Williams Technical & Economic Services, Inc., Princeton, N. J. 1 Present address, Oronite Chemical Co., San Francisco, Calif.
Coatings from Cyclohexene Oxide Derivatives
A
NEW TECHNIQUE was developed for preparing drying oil varnishes from diepoxides and unsaturated fatty acidsthe diepoxide, 3,4-epoxy-6-methylcyclohexylmethyl 3,4 - epoxy - 6 - methylcyclohexanecarboxylate (EP-201): was condensed with the fatty acid in such proportions that residual epoxide groups remained. The resulting adduct in the presence of a catalyst was then polymerized in solution. The reaction sequence is
This reaction scheme departs from the conventional means of preparing synthetic drying oil varnishes whereby a polymeric polyhydric alcohol and fatty acid are condensed at elevated temperatures. The EP-201 varnishes combine the excellent ultraviolet light stability of polyesters and the alkali resistance of glycidyl polyethers; also, they have a good combination of hardness and toughness.
0 0
-C-O-CHsCHa CHS EP-201
Fatty Acid 0
OH
I,
Adduct
1 3'18
Polymer
INDUSTRIAL AND ENGINEERING CHEMISTRY
The reaction of EP-201 and fatty acids such as dehydrated castor oil acid proceeds rapidly at temperatures of 160" to 200" C.-eg., a mixture containing an initial carboxyl-epoxide ratio of 0.45 had an acid number of less than one after 1 hour at 180' C. Higher charging ratios required longer reaction periods. The reaction is susceptible to catalysis by certain acids and bases. The ratio of fatty acid to epoxide affected the residual epoxide content in the adducts and subsequently influenced molecular weight of the varnish polymer. Furthermore, greater amounts of epoxide were consumed than can be attributed to esterification. Apparently a significant amount of hydroxyl-epoxide condensation occurred under the influence of catalysis by the fatty acid. Polymerization of the diepoxide-fatty acid adducts (Reaction 2) was greatly accelerated in the presence of certain acidic compounds such as boron trifluoride and stannic chloride. Boron trifluoride etherate initiated the reaction effectively at temperatures of 20" to 40" C. The reaction was exothermic and essentially complete within 1 hour after adding the catalyst, even at dilutions of up to 50% with solvent. Stannic chloride was also very effective but required temperatures of 80' to 110' C. for rapid polymerization. Basic initiators such as amines and sodium hydroxide were relatively ineffective in promoting the condensation of adducts derived from EP-201.
