significantly lower than 2.0. Such “lower ratio” silicatesfor example, sodium metasilicate-can provide necessary hydroxyl ion to hydrolyze Na3P30s.
source of sodium tripolyphosphate in practical detergent manufacturing processes, and even to eliminate the spray dryer now widely used in manufacturing light density detergents.
Discussion
Measurements on the hydrolysis rates of sodium trimetaphosphate to tripolyphosphate in detergent slurries containing less than 60Y0 solids show that the rate constants are essentially the same as the values estimated, assuming that the conversion takes place in the aqueous phase. This indicates that for most detergent slurries the rate-controlling step is the chemical reaction. O n the basis of this work, it appears that at 100’ C., the conversion of trimetaphosphate to tripolyphosphate is 97y0 completed in about 5 minutes. O n the basis of the kinetic rate data (of relatively dilute solutions) reported heretofore, this high conversion rate was not expected. The alkaline hydrolysis reaction of trimetaphosphate to tripolyphosphate hexahydrate is highly exothermic. The enthalpy change was measured to be -21.46 kcal. per mole. For a detergent slurry containing about 60 to 70% by weight of solids and at a temperature of about 60’ to 100’ C., the amount of water evaporated from the slurry due to the heat of reaction of a large amount of trimetaphosphate with 5oY0 NaOH, coupled with an additional large amount of water immobilized by the formation of Na6P3010.6 H20 (77) makes it possible to convert a pumpable detergent slurry directly into a solid built detergent having a relatively low density. Thus, contrary to what one might expect as the result of data available in the sodium trimetaphosphate chemical literature, sodium trimetaphosphate can be advantageously used as a
Acknowledgment
The author expresses his appreciation to C. F. Callis for supporting this investigation and to J. S. Metcalf for helpful discussions. literature Cited
(1) Bell, R. N., Znd. Eng. Chem. 39, 136 (1947). ( 2 ) Bjerrum, J., Schwarzenbach, G., Sillen, L. G., “Stability of Metal Complexes,” Part 11, p. 63, Chemical Society, London, 1958. (3) Brovkina, I. A., Zh. Obshch. Khim. 22, 1917 (1952). (4) Hatch, G. B., U. S. Patent 2,365,190 (Dec. 19, 1944). (5) Healy, R. M., Kilpatrick, M. L., J . Am. Chem. SOC.77, 5258 (1955); 79, 6575 (1957). ( 6 ) Indelli, A., Ann. Chim. 46, 367 (1956). ( 7 ) Kiehl, S. J., Coats, M., J . Am. Chem. SOC.49, 2190 (1927). (8) Kolloff, R. H., A . S. T. M . Bull. 237,74 (1959). (9) Quimby, 0.T., J . Phys. Chem. 58, 603 (1954). (10) Shen, C. Y., Dyroff, D. R., IND.ENG. CHEM.PROD.RES. DEVELOP. 5,97 (1966). (11) Shen, C. Y.,Metcalf, J. S., O’Grady, E. V., Znd. Ens. Chcm. 51. 717 (1959). (12) ’Van Waze;, J. R., “Phosphorus and Its Compounds,” Vol. I, Interscience, New York, 1958. (13) Van Wazer, J. R., Campanella, D. A., J . Am. Chem. SOC.72, 655 (1950). (14) Wieker, V. W., Thilo, E., 2.Anorg. Allgem. Chem. 306, 48 (1960).
RECEIVED for review February 16, 1966 ACCEPTEDJune 20, 1966
STARCH-D ERIVED GLYCOL GLYCOSIDE POLYETHERS FOR URETHANE FOAMS. PROCESS SCALE-UP, PERFORMANCE IN FOAMS, AND COST ESTIMATES R. H. L E I T H E I S E R , C. N . I M P O L A , A N D R . J . Archer Daniels Midland Co., Minneapolis, Minn. F. H. O T E Y Northern Regional Research Laboratory, Peoria, Ill.
R E I D
In a pilot-plant study of the preparation of polyethers from glycol glycosides obtained directly from starch, scale-up from a laboratory procedure was readily achieved to 1000 pounds of polyether per batch. Extensive evaluation of the polyethers for use in rigid urethane foams was made by appropriate formulation with PAPI or Nacconate 4040 isocyanates, with and without flame retardants, and with machine foaming. “Plant gate cost” of the polyethers was estimated to be around 15 cents per pound, based on current raw material and plant operating costs. Fixed capital investment was estimated at $375,000 for construction of a unit designed to produce 10,000,000 pounds of polyether per year. The low production cost of the new polyethers is expected to make them competitive with polyethers currently in use.
urethane foams are made by cross-linking~. polyethers R ’ T t h various isocyanates in the presence of a catalyst, surfactant, blowing agent, and, if desired, fire retardant agents. Polyethers now used by the industry are prepared by reaction of propylene oxide with such poly01 initiators as sorbitol, methyl glucoside, sucrose, and pentaerythritol until a liquid with the desired viscosity and hydroxyl number is ob276
I&EC PRODUCT RESEARCH A N D DEVELOPMENT
tained. (Manufacturers of propylene oxide should be consulted for safe handling procedures) The feasibility of producing polyethers from corn starch, by transglycosylation with ethylene glycol or glycerol followed by propoxylation, was demonstrated on a laboratory level (2-4). These studies established preferential conditions for preparing the intermediate glycosides: a 4 to 1 molar ratio of ethylene
glycol to starch, 248' to 266' F. reaction temperature, continuous reduced pressure throughout transglycosylation, and neutralization of the acid catalyst with alkaline earth compounds such as barium hydroxide. T h e reactants and catalyst were mixed at room temperature, heated to 248' to 266' F. at reduced pressure, and maintained in this temperature range for 30 to 40 minutes before removal of unreacted glycol. During the heating stage a gel or thick paste formed at about 220' F. that remained for 10 minutes and then become fluid. Initially, pilot-plant scale-up of the laboratory procedure proved difficult because the thick reaction mixture could not be agitated adequately to give good heat transfer. However, experimentation showed that gelation could be avoided by adding starch gradually to the glycol-sulfuric acid preheated to 248' to 266' F. Scale-up of the modified process was readily accomplished and several 100- and 1000-pound batches of polyethers were prepared. From the data obtained in the large-scale runs, a plant was designed and a preliminary cost analysis was made of the polyether process based on 10,000,000 pounds per year of production. The polyethers were evaluated for use in rigid urethane foam production by appropriate formulation with isocyanates and machine foaming. Characterization of the experimental foams suggested a preferred polyether hydroxyl number in the respective ranges of 380 to 420 and 420 to 440 for use with PAP1 and Nacconate 4040 isocyanates. Scaled-Up Polyether Preparations
A conventional 150-gallon stainless steel resin kettle, fitted with condenser, stirrer, and heating and cooling coils and capable of being pressurized to 50 p.s.i.g., was charged with 510 pounds of technical grade ethylene glycol, 4l/4 pounds of sulfuric acid, and 41/4 pounds of phosphoric acid. After the kettle was sealed, the charge was heated to 250' F. and the system was evacuated to 5 inches of H g pressure absolute. Pearl cornstarch weighing 403 pounds (352 pounds, dry basis) was then drawn into the kettle through a bottom valve over a period of 40 minutes while a temperature of 250' F. and a reduced pressure of 5 to 10 inches of H g absolute were maintained. Pressure was further reduced to 30 mm. of H g and the charge stirred at 250' F. for an additional 45 minutes to complete transglycosylation. Eight pounds of calcium carbonate were then added, under reduced pressure, to neutralize the acid catalyst. The etherification catalyst, 10.5 pounds of potassium hydroxide dissolved in 24 pounds of ethylene glycol, were added next in the same manner. Excess ethylene glycol was then removed over a period of 4 to 5 hours at 4 mm. of H g pressure as the temperature was increased to about 330' F. Total amount of unreacted glycol and starch moisture distilled from the reacting mixture was 462 pounds. After samples had been removed for analysis, the reactor contained about 490 pounds of the glycoside mixture. The
Table 1.
product was then heated to about 365' F. and 773 pounds of propylene oxide were metered in over a 4-hour period at a pressure of 46 to 50 p.s.i.g. to obtain a calculated hydroxyl number of 440. For this purpose, a positive displacement pump was used which was activated by a pressure switch to maintain a reaction pressure between 46 and 52 p.s.i.g. After initiation of the reaction, the temperature was slowly reduced to 335' F. Propylene oxide uptake rate increased rapidly until it exceeded the 16.7 gallon-per-hour capacity of the pump. A second glycoside preparation was similarly propoxylated to a calculated hydroxyl number of 41 5 by addition of propylene oxide over a 6-hour period at 315' to 370' F. and a maximum pressure of 50 p.s.i.g. Each polyether was dissolved in water to 60% concentration, 0.5 to 1% Hyflow Supercel filter aid was added, and the slurry was filtered through a Sparkler filter press. The filtrates were deionized by stirring overnight with Dowex 50 W-X-8 resin to a p H of 3.0 to 3.5, followed by agitation with Amberlite IR-45 to a p H of 5 to 6. Water was removed from the polyethers by vacuum concentration at 20 mm. of Hg, followed by azeotropic distillation with benzene. Before the preparation of two 1000-pound batches of glycoside polyethers, 100-pound runs were made in a similar manner. I n these early runs it was learned that phosphoric acid reduced coloration of the technical grade ethylene glycol. Each glycoside mixture was light tan after addition of either calcium carbonate or barium hydroxide. Upon addition of potassium hydroxide, however, the mixture became red to brown, and this color remained throughout propoxylation. Either a less alkaline catalyst or more rigid temperature control should result in light-colored polyethers. The color can be reduced to a Gardner color of 6 to 8 by treatment with activated carbon. Since polyether color did not significantly affect foam color, the preparations were not bleached. Properties of the starch-derived glycosides and polyethers, which are of importance in urethane foam technology, are given in Table I. Based on analysis of the distillates, approximately 0.8 mole of glycol reacted per gram formula weight of anhydroglucose unit. The glycosides contained 0.50 to 1.201, unreacted glycol that did not distill out. Excellent reproducibility was achieved in glycoside hydroxyl numbers, and the calculated hydroxyl numbers of the polyethers closely approximated analytical values. Foam Evaluation
Polyethers from 100-Pound Batches. Two gallons each of 24 experimental foam formulations were prepared from the 100-pound-batch polyethers and foamed in a Martin Sweets Miniature Model foam machine. Two additional foam formulations were prepared from commercially available polyethers as controls. The formulations and foam properties are given in Table 11.
Properties of Glycosides and Polyethers Made in Pilot Plant
Glycosides . Unreacted Hydroxyl glycol No. present, 70
Polvethers
100-POUND LOTS
1130
0.8
1150
1.2
1140
1. o
420
(440
460 360 440 41 7
75,200 195,200 26,140 174,200 95,000 1000-POUND LOTS 117,200 58,000
0.02 0.06 0.04 0.07 0.07
0.11 0.15 0.10 0.12 0.09
5.6 4.7 5.5 3.7 3.7
0.45 1.10 1.39 0.70 0.68
0.50 440 442 0.03 0.95 41 5 41 5 0.04 Karl Fischer moisture determination. * At 5% concentration in 10: 1 methanol and water.
0.00 0.03
5.2 6.4
... ...
1134 1140
a
41 0
VOL. 5
NO. 3
SEPTEMBER 1966
277
stability even in the presence of a fire retardant. Fyrol 6 reduced the humid age stability of foams made from polyethers with hydroxyl numbers lower than 460. Addition of Quadrol allowed the preparation of satisfactory foams from a polyether with hydroxyl number 380 without Fyrol 6 and a hydroxyl number of 440 with Fyrol6. T D I prepolymer foam systems based on a polyether with hydroxyl number of 460 appeared satisfactory without flame retardants, but the addition of Fyrol 6 gave foams with poor humid age stability. I t is evident that starch-derived glycol glycoside polyethers yield foams with properties equivalent to those made with commercially available polyethers. Glycol glycoside polyethers with hydroxyl numbers above 380 are generally adequate, but when used with Nacconate 4040 isocyanate in fireretardant foams, the hydroxyl number should be as high as 440. All B component viscosities (Table 11) were considered acceptable for machine foaming. Polyethers from 1000-Pound Batches. Ten gallons each of seven formulations were prepared from the 1000-pound polyether lots for foaming with a Jennings foam machine. The mix was poured from the machine at a rate of 45 to 50 pounds per minute into a 50 X 30 X 10 inch mold. Nitrogen was introduced into the head at 10 p.s.i.g. to give improved cell structure. Formulations and foam properties for the 1000-pound polyether batches are listed in Table 111. Excellent fine-celled foams with low K factors were obtained with each system. Other properties were comparable to those found for the 100pound polyether batches (Table 11).
I t was not within the scope of this investigation to establish optimum foam formulations. Instead, the experiments were designed to determine if the starch-derived polyethers were suitable for rigid urethane foam production and to find the preferred range of hydroxyl numbers for use with polymeric and crude isocyanates. PAPI formulations reported in Table I1 reacted somewhat slowly for machine foaming. Consequently, the foams obtained were coarse-celled, which apparently accounts for their high K factors. Later, by raising the TMBDA level from 2.0 to 2.7 parts and by adding 0.5 part of DABCO, excellent finecelled foams were produced having acceptable K factors. Other properties were good despite the low level of catalyst used. Excellent flame resistance was observed with PAPIbased foams when 1.1% phosphorus (20 parts of fire-retardant), exclusive of blowing agent, was included in the formulations. Physical strengths and dimensional stability of the foams were good even when polyethers of hydroxyl number as low as 380 were used in the presence or absence of fire retardants. Nacconate 4040-based foams (Table 11) appeared to be excellent with very fine cell structure but exhibited friability early in the cure stage. Friability disappeared, however, after the foam stood for 1 hour at 150' F. or overnight at room temperature. Friability probably resulted from insufficient catalysis since it was also observed with the controls. Foams prepared with Nacconate 4040 isocyanate were superior to those made with PAPI in physical strength and K factor but exhibited poorer flame retardancy and humid age stability. Polyethers with a hydroxyl number of 460 when used with Nacconate 4040 isocyanate gave foams with good humid age
B component Viscosity, cp.
460
460
460
460
440
440
Table II. Formulations and Properties of Foam Polyether, 420 420 380a 380" RS450b G435b
1860
3040
1860
1750
2085
830
1808
836
1060
456
2780
505 REAGENT,
Polyether Fyrol 6 Quadrol TMBDA DMEA: DABCO 3: 1 DC113 RllB
Isocyanate Density, lb./cu. ft. K factor Initial After 1 to 3 weeks
Compressive strength, p.s.i. Parallel PerDendicular Tensiie strength, p.s.i. Parallel Perpendicular Volume change, 7 0 Humid aging, 158 ' F., 100% R.H., days
80
80
20d
20
100
...
...
...
...
...
...
...
...
1.5 38 119
1.5 40 118
1.5 35 106
...
1.85
1.90
... 2.0
o:ii3
2.0
o:i&
...
80
20
...
100
... ...
80
20
100
...
...
...
...
...
2.7
2.7
2.7
2.0
1.5 37 117
1.5 37 112
1.5 36 113
1.5 36 104
1.5 34 105
1.5 33 97
1.90
2.05
1.95
1.80
1.95
1.85
1.95
... o:i43
o:i46
0.139
... ...
2.0
2.0
2.0
...
o:i43
...
80
20
...
... ...
...
... ...
...
2.0
2.0
1.5 34 99
1.5 38 118
1.5 38 118
1.80
2.20
2.0
...
...
FOAM 2.25
o.'i59
... 34.8 25.0
31.5 21.9
44.2 29.6
55.5 43.0
0.142
24.7 14.0
29.6 14.1
18.0 11.8
36.2 23.3
27.6 11.2
19.3 12.1
31.4 14.1
27.4 12.1
17.3 14.0
31.1 21.7
34.0 25.0
32.0 20.9
34.1 28.0
35.8 20.6
33.8 28.1
36.0 28.1
37.2 24.2
38.3 25.0
38.0 24.0
1 7
$7 +7 +7 $7
+8
+11 +8 +15 +15
+I7 +I7 +I4 +14
0
+8 +8
$11 +15 +11 +15
+10
+8
+I5 +15 $15 $11
+7 +7 +15
30
+lo +11 +11 +11
...
14
+7 +I1 +I1
+14 +I1 +I4
0 -3 -3
+3 +7 +7 +7
1
+4
+4 +4
+4 +4
+4 +8
+4 +8
+4 +4
+4 +4
$4 +4
+8
+4
+8
+8
0 -4
+4 0
... ...
2.40
3.00
2.65
...
2.05
... ...
2.00
+a 4 .
7
Flame resistance, minutes Bureau of Mines ASTM D1692-59T
278
100 20c
27.4 16.7
Dry aging, 212" F., days
a
100
...
NB
NB
+7
NB
...
NB
Blend of two polyethers, one part with O H No. 458 and four parts with OH No, 362.
l&EC PRODUCT RESEARCH A N D DEVELOPMENT
...
2.14 SE Commercial polyether (see Table ZV).
NB
...
5.30
B
.
. Phosguard C-22-R.
the starch through the reactor bottom facilitates immediate solid-liquid contact to minimize dry solids hangup in the reactor and solids entrainment in the vapors. The water in the cornstarch is distilled o f f in solution with ethylene glycol during starch cleavage, condensed, and collected with the ethylene glycol in a receiver for future ethylene glycol recovery. Instrumentation is provided to prevent loss of vacuum during starch addition. The mixture of ethylene glycol and water distilled during transglycosylation is collected in a receiver that is large enough for two batches. Ninety-nine per cent of the ethylene glycol in these distillates is recovered for re-use as a 98% bottoms product from a rectifier with eight valve trays and feed on the third tray. A feed-bottoms preheater exchanger for improved thermal efficiency and a vertical thermosiphon reboiler are used. When transglycosylation is complete (about 45 minutes), calcium carbonate is added as a dry solid through the bottom of the reactor in the same manner as the starch. The pressure is then further reduced to about 5 mm. of Hg and distillation of unreacted ethylene glycol in the reactor is begun. As this distillation continues, a slurry of potassium hydroxide, the propoxylation catalyst, in ethylene glycol is added. The undiluted ethylene glycol distilled a t this time is condensed, bypasses the receiver, and is pumped directly to storage for future use. The batch temperature is finally raised to about 360' F. until the ethylene glycol distillation is complete. The reactor vacuum source is then shut off. Propylene oxide is introduced at a controlled rate to maintain approximately 50 p.s.i.g. in the reactor and the temperature is held at 360' F. to initiate propoxylation. Once initiated, cooling is required to control the reaction rate. Instrumentation is provided to control both reactor pressure and temperature automatically. The total weight of propylene oxide required for each batch is determined from the weight and hydroxyl number of the glycoside and the final polyether
Test Procedures
Viscosity, per cent ash, acid value, and per cent water in the polyethers were determined as described in ASTM D 16386 l T . Hydroxyl numbers of the polyethers and glycosides were obtained by the acetic anhydride-pyridine method. Per cent free or unreacted glycol in the final glycoside was found by periodate oxidation (2) or gas chromatography (7). Foams aged for 72 hours or longer were cut into suitable test specimens and characterized by standard procedures : density, by ASTM D 1622-63; compressive (ASTM D 162159T) and tensile (ASTM D 1623-59T) strengths, on an Instron Model T T C M ; per cent open cell, on a Beckman air compression pycnometer; K factor, on a modified guarded hot plate, Du Pont Bul BA-3; flame retardancy, by ASTM D 1632-59T and the Bureau of Mines torch test; and dimensional stability, by measuring per cent volume change immediately after removal of specimens from a humid oven kept a t 158' F. and 100% relative humidity and from a dry oven kept at 212' F. Materials
The reagents used in the foam formulations and their source of supply are described in Table IV. Process and Engineering Design
Experience gained from the several pilot-scale polyether preparations allowed preliminary plant and operational designing. Various unit operations suggested for the Flant are detailed in the flowsheet (Figure 1). Ethylene glycol and acid catalysts are charged to the reactor and heated to 250" F. With a reactor pressure of 5 inches of Hg absolute, cornstarch is fed through a rotary lock from a weigh hopper and blown through a continuously grounded pipe into the bottom of the reactor a t a controlled rate. Adding
Made from 100-Pound Lots of Polyethers OH IVO. 460 460 460 460 440
2300
1228
440 440 Nacconate 4040
1840
790
2805
1060
80
60 20 20
... ...
100
80 20
2120
440
440
440
420
460
380
460 S580b Prepolymer
-
2300
850
904
1102
80
60 20 20
60 20 20
...
1024
2680
570
100
75 25
PARTS
100
...
... 2.0
.
I
.
1 5
36 97
80 20
...
2.0 ... 1.5 34 96
...
20
... 1.0
... 1.5 ...
80
...
80
...
1.5 34 93
1.5 33 91
1.5 1.5 35 104
1.5 35 104
1.5 1.5 34 103
1.5 34 103
1.5 1.5 34 99
1.65
1.75
1.70
1.75
1.80
1.65
1.80
1.80
1.85
o:ik
o:ii7
o:ii4
1.5 35 109
1.0 1.5 35 108
1.90
1.5
...
...
20
80
20 3.0 1.5 1.5 33 96
...
20
...
... e
...
...
20
...
e
...
...
2.0
...
1.5 38 124'
... 2.0 ...
1.5 37 122,
100,
PROPERTIES
1.65
1.70
o:i4o
... ...
o:ii9
o:iis
0.130 0.141
... ...
32.0 12.7
23.8 18.0
36.0 12.6
30.4 19.1
34.0 18.6
21.0 16.1
37.4 15.0
31.1 15.8
32.8 13.4
32.7 25.2
37.9 17.1
27.4 20.3
37.7 27.6
41.8 28.0
34.4 31.4
28.1 22.2
33.6 27.2
34.2 28.6
36.2 31.8
33.6 31.7
38.8 31.1
+11 $19 $27 $23
4-11
$7 4-22 $30 +48
4-3 $11 $14 $14
$18 +7 +7 -4
+7 $11
$7 $11 $15 $18
$11
4-19 4-19 1-23
+3 4-15 +18 22
$4 $4
0 $4
+4 $4
$4 +4
$4
...
...
Vircol82.
0.21
SE
... ...
0.21
SE
...
...
$15 $15 $4 $4
-4
0.20
0.4% dibutyltin dilaurateplus DMEA.
... f
...
...
0 $4
...
...
+27 $31 $31
1.70
1.90
1.70
o:ii6
o:ii4
o:i42
37.7 18.4
34.8 17.6
32.5 14.2
13.7
33.6 31.3
42.3 34.9
38.8 28.9
38.6 32.0
37.8 31.0
$3 $11
$3 $15 $22 +22
$7 $15 +19
$18 0 -8 -11
+22 +30
0
$4
0
0
0.113 0.126 o:ii9
+
0 0
+4 0
0.25 SE
0.23
SE
+I5 $18 0 $4
...
...
...
...
...
...
$11
... ...
...
+7 +37
-4 $11
+4
0.22
... ...
B
$4
Parts of prepolymer,
VOL. 5
NO. 3 S E P T E M B E R 1 9 6 6
279
Table 111.
Formulations and Properties of Foam Made from 1000-Pound Lots of Polyethers Polyether, OH No. 442
415
415
442
442
PAPZ
B component Viscosity, cp.
1550
980
442
415
Nacconate 4040
420
450
1410
525
705
REAGENTS, PARTS Polyether Quadrol Fyrol 6
31.8
RllB DC113
11.8 0.5 0.9
...
26.2
26.1
...
6.6 10.8 0.5 0.9
6.5 11.1 0.5 0.9
...
...
TMBDA DMEA: DABCO, 3: 1 Isocyanate
32.0
11.5 0.5 0.9
...
...
35.1
...
..
...
33.4
...
34.8
36.3
26.5 6.6
26.5 6.6
10.9 0.5
20.2 6.7 6.7 10.4 0.5
0.5 34.4
0.5 34.6
0.5 33.1
... ...
...
...
10.9 0.5
...
FOAMPROPERTIES Density, Ib./cu. ft. K factor Compressive strength, p.s.i. Parallel Perpendicular Tensile strength, p.s.i. Par allel Perpendicular yoVolume change, days Humid aging, 158" F. and 1 0 0 7 ~R.H.
1.96 0.115
2.05 0.114
2.03 0.125
33.7 20.4
42.0 18.8
40.8 12.3"
34.7 16.9
35.0 26.3
37.6 30.2
41 .O 31.7
36.9 33.4
39.9 30.0
36.0 25.3
38.9 29.5
12 13 13 14
14 16 17 20
13 15 16 18
10 12 14 16
14 19 23 30
10 13 15 18
8 9
Flame resistance, minutes Bureau of Mines ... ... 4.5 ASTM D 1692-59T ... ... NB Closed cell, yo 93 92 94 a No maximum to 20yo compression. T w o samples N B and two samples SE.
DC113 DMEA
Fyrol 6 G435
Nacconate 4040
PAPI Phosguard
Reagents Used in Making Foams Description
Source
Catalyst, triethylenediamine Surfactant Catalyst, dimethylethanolamine Fire retardant Methyl glucoside polyether, OH No. 435 Isocyanate
Houdry Process and Chemical Co. Dow Corning Corp. Union Carbide Chemicals Co. Stauffer Chemical Co. Olin Mathieson Chemical Corp. National Aniline Division, Allied Chemical Corp. Upjohn Co.
Polymethylene polyphenyl isocyanate Fire retardant
C-22R
Quadrol
Amine polyol, OH No.
RllB
Blowing agent, CClaF
RS450
Sucrose polyether, OH No. 450 Arothane 8760A-8764B Sorbitol-based TDI prepolymer system Catalyst, tetramethylbutanediamine Fire retardant
700
S580
TMBDA Vircol 82
280
1.80 0.124
38.6 14.6a
7
Material
1.81 0.123
28.4 14.9"
8
DABCO
1.95 0.108
28.0 14.5"
1 7 14 28
Table IV.
1.99 0.121
Monsanto Chemical co. Wyandotte Chemicals Corp. E. I. du Pont de Nemours & Co. Dow Chemical Co. Archer Daniels Midland Co. Union Carbide Chemicals Co. Virginia-Carolina Chemical Corp.
l&EC PRODUCT RESEARCH A N D DEVELOPMENT
4.0 SE 94
...
... 95
0.3 SE 94
...
... 90
Table V. Estimated Polyether Production Cost Based on Fixed Capital Costs of $375,000 and $470,000 Fixed Capital Znvestment $375,000 $470,000 Item Polyether Cost, CentslLb. Raw materials 12.813 12.813 Labor, direct (typical) 0.613 0.613 Labor, overhead 0.092 0.092 Supervision (typical) 0.070 0.070 Plant overhead 0.368 0.368 Utilities (typical) 0.241 0.241 Maintenance 0.262 0,289 0.112 0.141 Insurance 0.038 0,047 Taxes Depreciation 0.375 0.470 Total 14.984 15.144
hydroxyl number desired. Sampling and analysis of the glycoside are necessary to determine its hydroxyl number. The final polyether is cooled to 160' F., drained to the dilution tank, and dissolved in enough water to make a 66% nonvolatile solution. The polyether solution is filtered to remove inorganic salts and other solids, which amount to about 2y0of the polyether. Filter aid may be added as needed to improve filtration. Some of the polyether retained in the filter cake is recovered in wash water pumped through the filter press and used to dilute the next batch of polyether. The solution is then pumped through both acid and base ion exchange columns in series to obtain a product pH of 4 to 7. An agitated vertical thin-film evaporator is used to remove the water from the solution to a maximum water content of 0.1% in the final processing step. This type of evaporator is most effective a t stripping and handling the final product a t the outlet viscosity of approximately 15,000 cp.
B
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Polyether Production Cost
Preliminary cost calculations were made for a plant designed to produce 10,000,000 pounds per year of polyether from cornstarch based on the procedures described above and the flowsheet as outlined in Figure 1. For the production of two batches of polyether per day for 300 working days per year, a single reactor of 2700-gallon capacity would be adequate. T h e reactor and all necessary auxiliary equipment (such as rectifiers to recover ethylene glycol, dilution tanks, ion exchange columns, and thin-film evaporator) could be housed in a 40 X 40 X 50 foot high steel frame building of explosionproof design and constructed of corrugated Transite siding. Estimated fixed capital investment is $375,000 for design engineering, procurement, and construction of the production unit a t an existing plant site with normal services and facilities available. Accuracy range of the estimate is 10 to +25%, so the actual fixed capital investment is expected to be between $340,000 and $470,000. Plants at present equipped for propoxylation of polyols would require only a nominal conversion cost for adaptation to the new process. Based on currently published prices, the estimated raw material cost for polyethers produced from cornstarch in such a plant is 12.81 cents per pound. Plant operating cost is estimated at 2.17 to 2.33 cents per pound, based on $375,000 and $470,000 fixed capital investments, respectively (Table V). "Out-the-gate" cost of polyethers would be 14.98 to 15.14 cents per pound. Since these polyethers are 60 to 6570 propylene oxide, any reduction in the price of propylene oxide, below the current published price of 14*/2 cents per pound, would significantly reduce the cost of the finished polyether.
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Conclusions
The successful preparation of glycol glycoside polyethers in 1000-pound lots and use of the polyethers in making foams
demonstrate their good potential as a new industrial poly01 for the production of urethane foams. Because of the many objectives of this study, it was impractical to investigate each area in detail. I t is evident that experiments could be designed to cover a wider range of conditions and formulations. Also, more experience with the process and products should lead to smoother operation and better product uniformity. Acknowledgment
We thank H. S. White, H. J. Richards, S. M. Baker, N. D. Farel, C. C. Peloza, and W. J. Luckow of Archer Daniels Midland Co. for their assistance with laboratory synthesis, physical testing, pilot-plant laboratory scale-up, and foam preparation. literature Cited
(1) Otey, F. H., Bennett, F. L., Zagoren, B. L., Mehltretter, C. L., IND.ENC.CHEM.PROD.RES.DEVELOP. 4,228-30 (1965). ( 2 ) Otey, F. H., Mehltretter, C. L., Rist, C. E., J . Am. Oil Chemists' SOC. 40, 76-7 (1963). (3) Otey, F. H., Zagoren, B. L., Bennett, F. L., Mehltretter C. L., IND.ENC.CHEM.PROD.RES.DEVELOP. 4,224-7 (1965). (4) Ote F. H., Zagoren, B. L., Mehltretter, C. L., Zbid., 2, 256-9 (19637: for review March 14, 1966 RECEIVED ACCEPTEDJune 15, 1966
Division of Organic Coatings and Plastics Chemistry, 152nd Meeting, ACS, New York, N. Y., September 1966. A report of work done under contract with the U. S. Department of Agriculture and authorized by the Research and Marketing Act of 1946. The contract was supervised by the Northern Utilization Research and Development Division of the Agricultural Research Service, Peoria, Ill. Mention of names of equipment or specific industrial products does not constitute endorsement by the U. S. Department of Agriculture over similar equipment or products not mentioned.
NOVEL PROCESS FOR P R E P A R A T I O N OF INORGANIC FOAMS M A R C 0 W I S M E R A N D JOSEP..
F.
ss
Coatings and Resins Division, Pittsburgh Plate Glass Co., Springdale, Pa. Alumina and silica refractories possessing densities of less than 30 pounds per cubic foot have been produced using aromatic, unsaturated polyester resins as the foamable polymer system. The polyester system developed can support inorganic fillers over a temperature range of 25' to 1950' C. (77' to 3500' F.). Although foamed shapes undergo considerable shrinkage in that temperature range, this method produces low density refractories without internal cracks and without substantial change in the original foamed shapes. The fact that aromatic, unsaturated polyester foams perform better than other foamable polymer systems can b e explained through the kinetics of the thermal degradation of these polyesters. HE behavior of various polymers at elevated temperatures Thas been investigated, with special attention to the strength of polymeric materials in their carbonized form. This relates to the relationship of flame retardancy and char formation during the exposure of a polymer to heat. During this investigation the possibility of improving the fire retardancy of organic foams by the incorporation of inorganic materials was also explored. This work led into the field of inorganic foams. The insulating properties of a refractory material from 1500' to 1900' C. (2800' to 3400' F.) are improved a t lower densi-
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l & E C PRODUCT RESEARCH A N D DEVELOPMENT
ties. Many approaches for the production of low density, high heat-resistant refractories have been explored. However, refractories in a density range of 20 to 25 pounds per cu. foot have not been easily obtained. One of the methods for preparing refractories is a gradual application of heat u p to temperatures of 1900' C. (3400' F.), which will convert a mixture of organic and inorganic materials into an inorganic refractory. The idea of preparing inorganic refractories starting with organic foams containing inorganic fillers is not entirely new. Patent literature and government reports describe processes
