44 1
Ind. Eng. Chem. Prw! Res. Dev. 1904, 23,441-445 Masuda, Y.; Sato, H.; Kobayashi, T.; Teroda, Y. US. Patent 3826712, 1974. Ucci, P. A.; Anderson, N. T. U.S. Patent 3047456, 1962. Wllllams, J. C. I n “Industrial and Speclatty Papers”, Mosher, R. H.; Davls, D. S., Ed.; Chemical Publishlng Co.: New York, 1970; Vol. I V, Chapter 7. Zokosky, P.; Nadel, I. 0.;Hall, J. R. “Fibrillation of Commercial Acrylic Flber for use In Combustible Cartridge Case”, Contractor Report ARLCDCR82045, Armtec Defense Products, Inc., 85-901 Avenue 53, P.O. Box 848,
Coachella, CA 92236. Published by U S . Army Armament Research and Development Command, Large Caliber Weapon Systems Laboratory, Dover, NJ. Approved for public release.
Received f o r review February 6 , 1984 Accepted February 15, 1984
Flame Retardant THP-Prepolymer Application for Shingles Galoust M. Elgal’ and George L. Drake, Jr. Southern Regional Research Center, U.S. Department of Agriculture, Agricultural Research Service, New Orleans, Louisiana 70 179
One of the most prominent flame retardant chemicals used successfully for a decade on fabrics has been THPS, which is tetrakis(hydroxymethy1)phosphonium sulfate. When cured/polymerized with the incorporation of ammonia it forms a durable water resistant product. A study has been conducted to extend the use of THP-prepolymer previously prepared for fabrics to the application for shingles. This investlgatlon resulted from attention drawn to the need for fire protection of property using wood Shingles.
Introduction In a previous publication (Elgal et al., 1977a, and patent no. 4246031, Elgal et al., 1977b), a process was described for applying flame retardant to fabrics which could also be applied to wood. In this current study the process has been applied specifically to wood shingles. The information available at the Southern Regional Research Center for flame retardance testing was augmented by information from the Forest Products Laboratory (White, 1979; LeVan, 1982). Two test apparatus adapted to these tests were the Oxygen Index Tester and the 2-Foot Tunnel Furnace (61 cm) (Yeadon et al., 1965; Vandersall, 1964). The performance measurements with this test equipment have verified that flame retardance (not flame proof) can be achieved when wood shingles are treated with THP-prepolymer. Information on the industry requirements was provided by Western Red Cedar Shake Manufacturers Association (Knight, 1982) and International Conference of Building Officials (Ramani, 1982). Shingles were provided by Silver Tree Treating Company (Carey, 1982). The scope of this test effort was limited to flame testing. Prepolymer Chemistry 1. General. The flame retardent tetrakis(hydroxymethy1)phosphonium sulfate (THPS) was modified to a prepolymer for application to fabrics (Elgal, 1977). Subsequently, when the versatility of the process was noticed the application was also extended to wood (patent no. 4 246031, Elgal et al., 1977). For application to shingles three prepolymer compositions were evaluated, prepolymer P5, P7, and P8. However the prepolymers, reported in the previous publication noted above, may be used also. The figure and table from these references have been reproduced and modified to include addtional formulations (Table I). When ammonia gas is used, phosphoric acid is added to the THPS solution to acidify it to approximately pH 1. Gaseous ammonia, ammonium salts, or a combination of the two is then added to the acidified THPS. The
Table I
PI materials
prepolymer preparation P2 P4 P5 P6 P7
P8
ingredients, g
THPS(75%) 100 100 100 100 100 100 100 15 a H3P0, (85%) 24.4 24.4 (NH,),HPO, 14.8 25 14.8 u NH,H,PO, 10 60 a 14.8 u (NH4 )ZS04 X x x x a NH3 gas NaOH (12%) b a Use any one of the prepolymer formulations of P1 to P7. Add slowly while stirring vigorously to 80% weight of precipitation point.
ammonia reacts with the THP salt; a precipitate is formed which immediately dissolves into the solution forming what we refer to as the prepolymer (eq 1).
Polymer re-precipitation is effected by the addition of base. When ammonia gas is used the solution can be preheated with external heat to approximately 60 OC. Alternatively, the reaction may be started from ambient temperature and allowed for the exothermic reaction with ammonia to heat the solution. When ammonium salts are used alone, the mixture must be heated with external heat. The mixture may be heated to approximately 70 to 75 OC, held for 2 min, and then cooled down, or it may be heated to 85 to 90 “ C (near the boiling point) and then immediately cooled down. When the preparation of prepolymer is complete, and while it is still hot, it may quickly be tested by adding 2 mL of 25% sodium hydroxide solution to 2 mL of prepolymer. Stirring this mixture should produce a solid precipitate. The hot prepolymer should be cooled to a cold-water jacket to ambient temperature as quickly as possible to minimize deterioration.
This article not subject to U.S. Copyright. Published 1984 by the American Chemical Society
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I
Iri*
30 - 1
/ I
1
1
I
1
I
1
1
I
tube was outside the liquid to prevent liquid rising up into the tube and forming solid polymer. The stirrer speed was increased sufficiently to cause the ammonia gas bubbles to swirl in the liquid and react completely rather than to have a chance to effervesce from the liquid. A thermometer was suspended near the surface of the liquid and the temperature was monitored. When the temperature reached 85 " C the glass tube was removed, ammonia gas was shut off, and the flask was placed in an ice bath. The ice bath and the flask were both placed on the magnetic stirrer and allowed to cool down to 75 "C. The flask was removed from the ice bath and ammonia gas injection was resumed until the temperature rose to 80 "C. The cycle of ammonia gas injection and cooling was continued for a total of 4 cycles (Figure 1). During the ammonia gas injection the white polymer precipitate formation could be observed which dissolved into the liquid. At process completion the quality of the liquid prepolymer was immediately tested by adding 2 mL of 25% sodium hydroxide solution to a 2-mL sample of the prepolymer liquid. If a solid mass of white precipitate did not form the reaction flask was returned for another cycle of ammonia gas injection and cooling. Excess cycles of ammonia gas injection, e.g., 8 or 9 cycles, will increase the pH and cause the formation of an undesirable gel. 2.2. Prepolymer P7. To prepare prepolymer P7, a 500-mL Erlnmeyer flask was used as a reactor. Ingredients added into the flask were: 300 g of THPS (75%) and 200 g of ammonium phosphate monobasic (pulverized to remove lumps). A magnetic stirring bar was placed in the flask and the flask was placed on a magnetic heater/stirrer under a ventilated exhaust hood. A thermometer was suspended near the surface of the liquid and the temperature was monitored. The heating and stirring was continued to 85 " C (near boil). A flask was placed in an ice bath and both were placed on a magnetic stirrer to rapidly cool the liquid prepolymer. A 2-mL sample of the prepolymer was tested with 2 mL of caustic to verify that the product was satisfactory.
Test Equipment and Methods 1. Oxygen Index Test. Oxygen Index Flammability Tester, MKM Company, Model JD-14 was utilized to measure the minimum oxygen concentration in nitrogen that would support combustion. This equipment was constructed to ASTM Standard D-2863-76 (1977). This equipment contains oxygen and nitrogen pressure regulators and pressure gauges. These regulators and gauges permit the individual setting of the pressures of oxygen and nitrogen and thereby allow the selection of oxygen concentration in the combustion chamber. The combustion chamber is a vertical glass tube 8 cm in diameter and 38 cm in height. The sample of wood 1 X 1 X 7 cm was clamped in the chamber. A candle size natural gas ignition flame was applied to the wood for 10 s. This duration was used in all the tests and the flame testing was applied to the ends as well as to the sides of the wood. The combustion characteristics were thus observed. If the flame went out the oxygen concentration was raised and the test was repeated with a new wood surface or sample. When a sustained combustion was observed, the test was repeated with a new wood surface or sample at a slightly lower oxygen concentration. This test procedure was used to determine the concentration of oxygen (Oxygen Index) at which combustion is just sustained. 2. Flame Test Tunnel. A pilot plant scale Flame Test Tunnel was utilized to test fire-retardant performance. The construction of this Flame Test Tunnel is described by Vandersall (1964). Information on the utilization of this
Ind. Eng. Chem. Prod. Res. Dev., Vol. 23, No. 3, 1984 443 Table I1 New Shingle Oxygen Index Flammability Tests oxygen treatment index untreated 0.259 prepolymer P8 0.384 prepolymer P5 dilute 0.401 prepolymer P5 concentrated 0.404 Table 111. Old Shingle Oxygen Index Flammability Tests oxygen index treatment 0.276 untreated 0.385 prepolymer P8 0.400 prepolymer P5 dilute (pre-treat NaOH) 0.402 prepolymer P5 concentrated 0.405 prepolymer P5 dilute 0.410 prepolymer P5 concentrated (pre-treat NaOH)
equipment was obtained from Yeadon et al. (1965). The wood specimen 61 cm (24 in.) long and 10 cm (4 in.) was placed in the equipment at a 45O angle. A Bunsen burner was positioned at the base of the wood so that the blue flame impinged on the wood. Natural gas supplied to the Bunsen burner was regulated for consistency and uniformity of gas pressure for all tests. The flame was applied for 5 min. All specimens were stored at uniform temperature and humidity prior to the tests. The weight loss (determined by weighing before and after the flame test) was recorded. Experimental Results 1. Penetration of Prepolymer in the Cedar Wood. Sections of shingle were cut and treated with prepolymer to test the depth of penetration. A dye used for similar tests on fabrics (Vitrolan blue) was added to the prepolymer to observe the penetration of liquid. Four tests were made: shingle wood dipped in concentrated prepolymer under atmospheric pressure; shingle wood kept under vacuum (21 in. Hg) for 2 h, then concentrated prepolymer poured on the wood while still under vacuum; above two tests repeated but instead diluted prepolymer (one part prepolymer and 0.5 part water by volume) was used. The penetration depth was approximately 1 mm with the penetration for the dilute prepolymer being a fraction of a millimeter greater than for concentrated prepolymer. When vacuum conditions were used it was observed that the prepolymer pentrated deeply only at various minute veins in the wood lengthwise at the ends where the wood is ragged and porous. 2. Oxygen Index Tests. Wood specimens 1 X 1 X 7 cm were tested in the Oxygen Index Tester. The tests of untreated new and old wood shingles produced sustained combustion at approximately 26% oxygen; however, sustained combustion was retarded to 40% oxygen for wood treated with prepolymer (Tables I1 and 111). 3. New Long Shingles: 61 cm Long, 10 cm Wide, 2.5 cm Thick (24 X 4 X 1 in.). A series of 15 tests were made with conventional long shingles. Of these samples, 14 were treated in various combination of applications and 1 was untreated. The shingles were weighed before and after the tunnel flame tests and their weight loss was recorded (Table IV). The weight losses were between 5 and 8.5 g for treated shingles as compared to weight loss of 18.5 g for the untreated one. It was observed that (a) the easier one-coat prepolymer P8 provided equivalent results to the two-step process; in fact, the weight loss was on the top of the list and recorded 5.0 g as compared to 8.5 g for concentrated prepolymer P5; (b) in general no distinct advantage was gained by dipping the shingles in solution as compared to brushing; (c) the prepolymers P5, P7, and
Table IV. Weight Loss in Flame Test Tunnel [New Long Shingles: 61 cm Long, 10 cm Wide, 2.5 cm Thick (24 X 4 X 1 inJl wt scorch treatment loss, g length, cm prepolymer P8, dipped, two coats 5.0 18 5.5 19 prepolymer P8, brushed, one coat 1. 25% NaOH, 2. prepolymer P5 5.6 15 concentrated 5.6 16 1. prepolymer P5 conc., 2. 25% NaOH; dipped 6.0 15 prepolymer P8, dipped 6.1 15 1. 25% NaOH, 2. prepolymer P5 dilute; dipped 6.2 15 1. 12% NaOH, 2. prepolymer P5 conc.; dipped 6.2 15 1. 12% NaOH, 2. prepolymer P5 conc.; dipped 6.2 16 1. 12% NaOH, 2. prepolymer P5 dilute; dipped 6.2 15 1. prepolymer P7 conc., 2. 25% NaOH; dipped 7.5 17 1. prepolymer P7 conc., 2. 25% NaOH; dipped 8.0 17 1. prepolymer P5 dilute, 2. 25% NaOH; brushed 8.2 17 1. prepolymer P5 dilute, 2. 25% NaOH; dipped 8.5 19 1. prepolymer P5 conc., 2. 25% NaOH; brushed 18.5 61+ untreated Table V. Weight Loss in Flame Test Tunnel [New Short Shingles: 40 cm Long, 9 om Wide, 1 cm Thick (16 X 3.5 X 0.375 in.)] wt scorch treatment loss, g length, cm 6.5 19 prepolymer P8, brushed prepolymer P8, two coats, brushed 7.0 18 1. prepolymer P5 dilute, 2. 25% NaOH, 11.0 19 brushed 1. prepolymer P5 conc., 2. 25% NaOH, 14.0 17 brushed untreated 32.0 40+
P8 provided equivalent results for wood applications; (d) the differences in weight loss for many of the items on the list were very close to each other and the effect of wood porosity could easily move the items in the order of the listing; (e) combustion of the untreated shingle continued after removal from the test tunnel while the treated shingles did not sustain combustion. Table IV also lists the scorch length for each of the applications. These lengths were 15 to 19 cm and essentially the same for all treatments. In comparison the scorch length extended the full dimension of the untreated shingle or 61 cm. This indicates that had the test tunnel accommodated longer shingles and if longer shingles were available the scorch length would have been considerably longer. 4. New short Shingles: 40 cm Long, 90 cm Wide, 1 cm Thick (16 X 3.5 X 0.375 in.). A few short thin shingles were available for testing. Because of their thin dimension the total heat capacity was lower, causing over-heating and the tendency to crack under the intense heat of the blue flame. Five shingles were tested, four treated with flame retardant and one untreated. The shingles were weighed before and after the tunnel flame tests and their weight loss was recorded (Table V). The weight losses were between 6.5 and 14 g for the treated and 32 g for the untreated. The lowest weight loss was for the one-coat prepolymer P8 (6.5 g) and the highest weight loss was for concentrated prepolymer (14 8). The observation was that the concentrated solution did not penetrate into
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Table VI. Weight Loss in Flame Test Tunnel [Old Long Shingles 61 cm Long, 10 cm Wide, 2.5 cm Thick (24 X 4 X 1 in.)] wt scorch treatment loss, g length, cm prepolymer P8, two applications, brushed 4.5 18 6.5 18 prepolymer P8,brushed 1. prepolymer P5 dilute, 2. 25% NaOH; 9.0 20 brushed 1. prepolymer P5 conc., 2. 25% NaOH, 10.5 20 brushed untreated 22.0 61+
the cedar wood as well as the dilute. The observation was that the concentrated solution did not penetrate into the cedar wood as well as the dilute. Table V also lists the scorch lengths for each of the applications. These lengths were 17 to 19 cm and essentially the same for all the treatments. In comparison, the scorch length extended the full dimension of the untreated shingle or 40 cm. This indicates that had the shingle been longer the scorch length would have been considerably longer. 5. Old Shingles: 61 cm Long, 10 cm Wide, 2.5 cm Thick (24 X 4 X 1 in.). From a local building renovation project several old shingles which had weathered for 5 years were obtained and treated with prepolymer to simulate application to existing roofs. The shingles were weighed before and after the tunnel flame tests and their weight loss was recorded. Five shingles were tested, four treated and one untreated (Table VI). The weight losses were between 4.5 and 10.5 g for the treated and 22.0 g for the untreated shingles. The lowest weight loss was 4.5 g for two coats of prepolymer P8 and highest weight loss was 10.5 g for concentrated prepolymer P5. The observation was that the concentrated solution did not penetrate into the cedar wood as well as the dilute one. Table VI also lists the scorch length for each of the applications. There were 18 to 20 cm or essentially the same for all the treatments. In comparison the scorch length extended the full dimension of the untreated shingle or 61 cm. This indicates that had the test tunnel accommodated longer shingles and if longer shingles were available the scorch length would have been considerable longer. 6. Application of THPS to Internal Roof Structure. The structural wood supporting the roof may also be treated with flame retardant. Since this structure is not exposed to rain it does not need to be water resistant. Therefore, unmodified commercial THPS may be applied to the wood directly. Through experimentation it was determined that THPS (75%) diluted with water (THPS 1 part to water 0.5 part by volume) provided better absorption into the wood, easier drying, and greater economy than the undiluted material. Flame tunnel tests were performed with construction pine wood (commonly known as 2 by 4) treated and untreated wood. The retardance of combustion for wood treated with dilute THPS resulted in a weight loss of 11 g as compared to 18 g for untreated wood (Table VII). The charring lengths were 29 cm for treated and 61 cm for the untreated woods.
Discussion 1. General. Two modes of application on shingles were used, i.e., dipping and brushing. Spraying should give the same results as the other two methods; it was not considered because spraying is in general suitable for large surface areas in the absence of air drafts and wind conditions. New shingles come in bundles and would not be adaptable to
Table VII. Weight Loss in Flame Test Tunnel [Construction Pine Studs (2 X 4 in.)] w t loss, scorch Treatment g length, cm THPS dilute, brushed 11.0 30 untreated 18.0 61+
spraying. Old shingles on roofs would pose air draft and wind conditions and would cause the spray of prepolymer and caustic to move into the surroundings. No weathering tests involving ultraviolet radiation and simulated rain were conducted in this test series. The THP-prepolymer was previously tested for application to fabrics and subjected to wash and dry cycles successfully. Weathering condition simulations, such as exposure to ult7,aviolet light, would require further investigation. Both resistance to rain simulation and ultraviolet light are required to conform to ICBO Codes. With respect to these requirements, the ultimate and realistic tests would be achieved in actual usage over the years where industrial pollutants (e.g., acid rain) and unusual environmental conditions (e.g., volcanic erruptions) may be encountered. It is concluded that it is more practical to interpret code requirements for flame retardance in the same category as house painting or termite treatment where a regularly scheduled application is planned and inspected. 2. Effect of Heat on Prepolymer. Small quantities of prepolymer, such as 1 or 2 L, are more sensitive to ambient temperature variations and should be kept in a cool place. It should be noted that approximately 4 L of the prepolymer has been stored in a refrigerator for 5 years and is still in fresh condition. Maintaining a temperature below 20 OC is advisable to retain stability. 3. Test Method for Prepolymer. To test the quality of the prepolymer either after the manufacture or after aging, use 2 mL in a small beaker. Add 2 mL of sodium hydroxide (25 to 50% concentration). Caution: the mixture gets hot and can splatter. Stir with a spatula or glass rod for a few seconds. It should form a precipitate that looks like “cottage cheese”. This is the flame retardant polymer. If it forms a milky solution or foams, add an additional portion of sodium hydroxide to confirm that the prepolymer is not satisfactory. The prepolymer is also a flame retardant whether the test produces a satisfactory test or not; it becomes an insoluble flame retardant when satisfactorily polymerized.
Summary and Conclusions The method of flame retardant application presented here has been surface application with aqueous solution. This is the least costly method and is in contrast to two alternate methods, that is, application and penetration under high pressure and by surface application with special solvents. Surface application with aqueous solution is the more practical considering cost and effectivity; the others tend to be cost prohibitive even though likely to be somewhat more effective. The commercially available THPS can be used directly as a flame retardant on interior structures where weathering is not encountered. At least 60% improvement in flame retardance was measured with pine wood based on Flame Tunnel tests. The THP-prepolymer used as a flame retardant on cedar wood shingles provided flame retardance on both new and old existing shingles. At least a 50% improvement in flame retardance was measured by utilizing the Oxygen Index Tester and Flame 2-Foot Flame Tunnel furnance. The ideal goals for the development of flame retardant treatment for shingles are that (1)cost is to be negligible;
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(2) it meets ICBO codes and ita equivalents; (3) it be flame proof; (4) it be durable under all expected conditions indefinitely. At the time of this writing, property owners and the wood industry are waiting for a flame retardant to meet the above requirements before treating wood shingles. This study is addressed to those who may like to do something instead of nothing. It is not always that a full grown burning tree falls on a roof accompanied by 100 mph wind. Frequently it is a branch or a fire cracker. The cost of raw materials for THP-prepolymer flame retardant at current prices is $2 to $6 per square meter of surface depending on quantity of purchase and one-side or both-side treatment. Additional research could be performed for durability to environmental conditions. Registry No. THPS, 55566-30-8; (THPS).(homopolymer), 65257-05-8.
Literature Cited Amerlcan Society for Testing and Materials, 1977. ASTM D2863-76, Phiiadelphia, PA.
Carey, James and Nancy, Sllver Tree Treating Company, Gates, OR 97346. Supply of shingles for testing, 1982. Elgal, G. M.; Perklns, R. M.; Knoepfler, N. B. ACS Symp. Ser. 1977a, No. 58, 249. Elgal, G. M.; Perklns, R. M.; Knoepfler, N. B. U S . Patent 4246031, 1977b. Knight, Clyde, Western Red Cedar Shake Manufacturers Association, Edmonds, WA, 98020, 1982, communication. LeVan, S. L., Forest Products Laboratory, USDA, Madison, WI 53705, 1982, communlcatlon. MKM Company, Jeffersonvllle, IN 47130. Ramani, C. P., Internal Conference of Bullding Offlciais, Whittier, CA 90601, 1982, communication and ICBO Publlcation. Vandersaii, H. L. “Useof a Small Flame Tunnel in the Laboratory Evaluation of the Flame Spread Rating”, Monsanto Special Report No. 6090, May 5, 1964. Whlte, R. H. WoodSci. 1979, 72(2), 113-121. Yeadon, D. A.; Verberg, G. B.; Rayner, E. T.; Doiiear, F. G.; Hopper, L. L., Jr.; Dupuy, H. P. Roc. Annual Tung Ind. Assoc. 1065, 32, 18.
Received for review January 11, 1984 Accepted March 21, 1984 Names of companies or commercial products are given solely for the purpose of providing specific information; their mention does not imply recommendation or endorsement by the U.S.Department of Agriculture over others not mentioned.
Chelating Resin Functionalized with Dithiocarbamate for the Recovery of Uranium from Seawater Iwao Tabushi, Yoohlakl Kobuke, NorHake Nakayama, Takao Aokl, and Atsushl Yoshlzawa Department of Synthetic Chemistry, Faculty of Engineering, Kyoto Universlty, YoshMa, Kyoto 606, Japan
Chelating resins having dithiocarbamate groups were examined for the recovery of uranium directly from seawater. The resins studied adsorbed uranyl ions with sufficiently high rates, 50 pg of uraniumlg of resin per day from natural seawater. The uranyl ion adsorbed on the resin was liberated quantitatively by treatment with a 10% ammonium carbonate solution. Repeated adsorption and desorption did not cause any appreciable deterioration of the resins. The maximum adsorption was estimated to be 5.1 mg/g of adsorbent. This resin was tested with a contact system that utilized sea current directly. Immersion of the resin in the Kuroshlo current gave 40 pg of uranium/g of resin after one day.
Introduction The amount of uranium dissolved in the oceans of the world is estimated to be ca. 4 billion tons. Even a small percentage, e.g., 10% of the total amount, could provide huge energy resources that would be enough to fuel 2.4 million nuclear power plants X years, based on the assumption that a plant of average size requires 170 tons of uranium per year. Thus the discovery of an efficient way of recovering uranium directly from seawater would alter that aspect of the world-wide energy problem dramatically. A recovery program was begun in Great Britain in the early 1960’s. This was followed by projects in various countries in universities and by private companies. Several methods have been proposed coprecipitation, adsorption, flotation, solvent extraction, biological accumulation, and others. Of all of these, the adsorption method has been accepted as the most promising in recent years. The development of the use of hydrous titania opened the way for direct recovery (Davies et al., 1964; Keen, 1968). Its success stimulated the study of various organic chelating resins resulting in the preparation of various new types of useful resins (Tabushi et al., 1979). Even so, the process still needs improvement in many areas, e.g., adsorption rate, equilibrium adsorption ca-
pacity, mechanical as well as chemical stabilities, and so on. We have proposed the use of macrocyclic compounds, which have extraordinarily large stability constants, as well as high selectivity toward uranyl ions (Tabushi et al., 1979, 1980). There are still a variety of approaches remaining for the use of other chelating u n i k Here we have exploited one possibility of using a polymer having dithiocarbamate as a chelating unit. The resin successfully recovered uranyl ion a t a high adsorption rate, 40-50 pg of U/(g of resin day), directly from natural sewater or natural sea current. Experimental Section Adsorbent. Dithiocarbamate resin was donated by Professor Fujio Mashio (see Acknowledgment). The detailed preparation was reported in Tokkyo Koho (in Japanese; Mashio, 1983). The following description is from the English abstract of the original patent: An equimolar mixture of butane-1,2,3,4-tetracarboxylic acid, (meso form, 117 g) and tetraethylenepentamine (94.5 g) was kneaded well with 100 mL of water. The viscous material obtained was heated at 145-155 OC for 2 h. The light-brown transparent resin was then suspended in water and water-soluble material was filtered off. A light-yellow resin (3-A) was obtained as fine particles (solid fraction: 41.3%, yield on the dry resin: 181.7 g). The resin (3-A) was
0196-4321f84f1223-0445$0l.50/0 0 1984 American Chemical Soclety
