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.
EPOXY R E S I N S The proportion of fatty acid and diepoxide charged in the adduct preparation was significant in determining molecular weight of the polymer. The optimum formulation was derived from a carboxyl-epoxide ratio ranging between 0.40 and 0.55. Lower proportions of
Table 1.
EP-201 Varnishes Have Good Resistance to Caustic, Boiling Water, and Ultraviolet
% Acid On Solids
Flexibility; In. Lb. Impact
45 45 45 45 53
108 80 100 88 108
Exc. Exc. Exc. Exc. Exc.
Exc. Good Good Exc. Exc.
87 90 90 85 66
40 40 45
108 108 108
Exc. Exc. Exc.
Exc.
69 73 87
i.
Fatty Acid
x
fatty acid tended to give gelled products, whereas higher proportions led to polymers which had unnecessarily low molecular weights. A small quantity of water added to the product decreased solution viscosity significantly. Where a semigelled poly-
D Ca Linseed Soya bean Soya beanb Tung
them. Resistance M'ater Caustic
Hardness; U.V. Sward Resistance
Formulation Conventional epoxided Alkyds EP-20la
x
Exc.
Poor Good Good
Dehydrated castor. Varnish contained 10% of butylated melamine resin (American Cyanamid Co., Cyme1 Resin 448-8. 0 Varnish prepared from 0.55 adduct and final viscosity was 1070 cp. at 50% solids. Care was necessary t o avoid premature gelation. d Epoxide equivalent weight of about 1000 plus dehydrated castor oil acid. e From American Cyanamid Co., Rezyl Resin 330-5.
C. W. McGARY, Jr., C. T. PATRICK, Jr., and RALPH STICKLE, Jr.
An Epoxy Resin from Phenolphthalein
designed. Phenolphthalein and epichlorohydrin were allowed to react with 2 or 3 moles of sodium hydroxide in the presence of a limited amount of water. The resin was isolated without being washed with water or dilute acid. A large ash content would have indicated the presence of an organic acid salt. The low ash content found experimentally eliminates structure VII. Comparing the theoretical epoxy equivalents of mono-, di-, and triglycidyl phenolphthaleins with the experimental values, it appears that the glycidyl product of phenolphthalein has approximately two epoxy groups per molecule. The saponification value indicates that the second
Dmiw
+
Poor
mer formed, 1% of water based on solids, converted the gel to a mobile solution. One explanation for this is that the inorganic initiator entered into the polymer chain by forming inorganic ether linkages, e.g., if boron trifluoride were used, the borate should have been easily hydrolyzed. Adding water to the polymer mixtures could also reduce viscosity by reducing interpolymer hydrogen bonding. The polymerization reaction was carried out in enough solvent, usually xylene, to give a polymer concentration of about 50 to 55%. The varnishes also had a high tolerance for aliphatic solvents. Film properties were determined using conventional dip-coating and testing methods. T o obtain optimum properties by air-drying or baking at 160' C., dryers such as cobalt and lead naphthenate were used (Table I). The coatings had excellent resistance to caustic (20% sodium hydroxide for 24 hours), boiling water (1 hour), and ultraviolet light (2 weeks at 60' C.).
THE PAST 20 years a considerable quantity of literature has appeared on epoxy resins related to their synthesis, formulation, and application. The major portion of this literature is concerned with the resinous materials prepared from epichlorohydrin and bis-(4hydroxyphenyl)-dimethylmethane (bisphenol A). These resins also make up the bulk of the commercial market. Recently more interest has been shown in the synthesis of new epoxy resins, including glycidyl derivatives of other phenols and epoxides from the peroxide epoxidation of olefins. The purpose of the research reported here is to synthesize a new epoxy resin with higher heat distortion temperature and better solvent resistance than that obtainable from resins based on bisphenol A.
The condensation with 2 moles of epichlorohydrin could conceivably give any or all of the three structures V, VI, or VII. Of these three possibilities, V would be formed from I, V I from 111, or VI1 from either I1 or IV. If 3 moles of epichlorohydrin condense then only structure VI11 is possible, and could be formed from either I1 or IV. To determine which of these four structures is predominant in the resin, the experiments shown in Table I were
Table 1.
The epoxy resin of phenolphthalein can be prepared by condensing phenolphthalein with epichlorohydrin in the presence of alkali at 105' to 115' C. for 2 or 3 hours. According to the literature (7) the reaction between an alkali and phenolphthalein is shown by the equation on the following page.
Epoxy Resin of Phenolphthalein Prepared by Using Different Amounts of Sodium Hydroxide No.
69-1 16-1 84-1 91-1 110-1
Structure Study
a
Research Department, Union Carbide Chemicals Co., South Charleston, W. Va.
Monoglycidylb Diglycidylb Triglycidyla Per mole of phenolphthalein.
Moles NaOHa
Epoxy Equiv./ 100 G.
3 3
0.36 0.40 0.42 0.35 0.38
2 2 2
Sapon. Value
... 135
Ash,
%
132 128
0.04 0.06 0.00 0.00 0.02
150 130 111
0 0 0
..I
Theor. Value 0.267 0.465 0.595
Phenolphthalein. ~~~~~
VOL. 52, NO. 4
APRIL 1960
31 9
