Document DVEvg8REzL5jNL2kxvBMQpYO

cc : hT. K. ^ERDTVISJT0HAL TRANSFER OF R. M. TECHNOLOGICAL DEVELOPMENTS SIT. V/. F. B. D. T. Dr. J. H. Lum M. C. Director, R&D J. S. Organic- Chemicals Division FROM IH FUES OF THt AROCLOR 1242 V/ITH IHPROVEQygk laboratory DIELECTRIC PROPERTIES PLEASE PFXljfftf: 1'iom s Glue sen-: Zienuy Mo wry Throdahl Hayes '\ DESCRIPTION OF PROJECT TR-25, R&E, 1959* October 15, 1959 oy te ^ ^ /- r'V ' \UU ^ '. A study of a market survey report by John S. Harris of Organic Division Development (Ref. l) and our own preliminary investigations led us to the conclusion that an attempt should be made to Improve the following properties of Aroclor 1242: (a) Dielectric constant (Dk) (5**825) (b) Pour point (-19C) (c) High temperature stability . We have had gratifying success in improving property (a) and our results constitute the subject of this report. " Result: . A dielectric material, Aroclor 1242' with a Dk of .6.7-7.2, and a practical procedure for its preparation believed subject to patent coverage. . HISTORICAL BACKGROUND nWe have very few products of which we are the only manufacturer, and the Aroclor family is a prime examples It has had a long and profitable history and last year (1955) some 55 million pounds were sold for over $5 million - two-thirds of this for electrical use. Notwithstanding its low price, it gives us a very good return on investment. But with our protective patents gone, and a half dozen other chemical manufacturers looking at the Aroclors, v/e stand a good chance of losing our hold on these products at any time. With the electrical sales alone estimated in 195ifrom 50 to 55 million pounds, this would be quite a loss." This quote from Ref. 1 explains v/hy we are carrying out a research program in this area. ___________________ ._ *Thls report was written by Harold Weingarten; Van R. Gaertner, Group Leader. ______ ___ _ l * ... . 1 DSW440S31 STLCOPCB4102545 2 The process described in this report was developed as a direct result of a three-phase fundamental study carried out during the last two years. ". Phase one, the study of the Gonberg reaction, permitted the labor atory preparation of high Dk chlorinated biphenyls leading to the discovery that an increase of one or two units in the Dk of chlorinated biphenyl mixtures did not adversely influence the power factor or resistivity. Phase two, the study of biphenyl chlorination, revealed 2,4*1-2d*lc4hloroblphenyl as the precursor of most of the high Dk trichloroblonenyls. A summary of-this work Is given in Table I. And Phase three, the study of the distri bution of isomers in Aroclors, revealed Aroclor 12^2 to be an excellent source of 2,4'-dlchloroblphenyl (see Table III). Figure 1 summarizes the isomer distribution study made on Aroclor 1242. The vapor phase chromatogram of A.roclor 1242' is included for comparison. Also included in Figure 1 are the estimated Dk's of the trichlorobiphenyls arising from the 2,4'-isomer. . - This project was begun in February of 1957 and the total expense through June, 1959* was $89,965* C H AR AC TERIZATION Process Method (a) , 1. Aroclor 12^2, made by direct chlorination of biphenyl (not by blending 1221 and 1242), is fractionally dis tilled* (see Figure 2) and the fraction rich in 2,4'dlchloroblphenyl (85 to 1005&)** is used in the next step. 2. The fraction rich in 2,41-dlchloroblphenyl is chlorinated to the trichloro level according to the standard Aroclor processing conditions. Purification is also carried out by the standard Aroclor method. .' 5. The low boiling fractions can be recycled through the chlorlnators or used as Aroclor 1221. 4, The high boilers are chlorinated to higher levels for . non-capacitor uses. A sample of Aroclor 12601 was pre pared in this way and sent to Organic Division for comparison with standard Aroclor 1260. Its physical . properties and Dk were found to be essentially identical to the standard Aroclor 1260. Table II described.the comparison (Ref. 4). Minor instability was apparent ; but can presumably be corrected by proper treatment. *For details see. references 2 and J>. **Vapor phase chromatography is used to follow the distillation and determine the purity of the desired fractions, --- ' DSW 440832 % STLCOPCB4102546 2 26^ 4 74 - 3I TABLE I BIPHENYL CHLORINATION STUDY 2 HoAC :CC14 <'Cl2 R.T. Ci2 40 ^ TM Benzene or CCI4 4 57 32 68 4- * 45 55 22 78 > 46 54 No reaction in 40 day3 \ Must give all six isomers in about the same order of magnitude DSW 440833 STLCOPCB4102547 Figure 1 -4Aroclor Component Study tCoDt fc> j>r -- w p 4 P CD 3 o H- o M p P- Ps fj p ps w cl- o H- i-o M l-1 ct S' Ct P P to 3P cpt p ct o: H* CO < H- P(g 3 P 3 ct CO aM o_rvA-o Vz/ wa M / \ DSW 440834 STLCOPCB4102548 Pye Argon Chrom atogram s (Condensed) 5 MATERIAL FLOW FOR PRODUCING 15 TT LB /Y R OF MODIFIED AR0CL0R 1242 FROM AR0CL0R 1252 H*s <D ro Mro $y>y--i >< a\ \jj *' 119l ,b51/ y4Xr 10 lybJ V/UyArJ L v | M VJ1 O* VJ1 *-- \0<; D-^ M o VjJ ro M n* VO -P 'vNf X M o VoJ w >oo1 1--1 M O' O N. *i Co ro -fr ro _ o z->r - 3 -* D p c-*t zos __ u >1 Vt STLC0PCB4102549 6- - TABLE II Aroclor 1260 ~, Property______________ Lot T-656 ' 'Aroclor 1260 Specifications Color, APHA 45 150, max. Condition Clear Clear Sp. Gr. at 90/15.5C 1.555 . 1.555-1.566 Acidity, mg ROH/gm. . 0.002 0.014, max. : Moisture, ppm 20 35* max. Viscosity at 210C, SUS 72.4 72 - 78 Refractive Index at 25C 1.6459 1.6455 - 1.6470 Inorganic Chlorides NDA . No detectable amount Pour Point, C . 28 - 25 - 54 Distillation Range ` ASTM D-20 ' *1 -' 10^ Distilled by wt. 392C 585-598C 50$ Disti-lled by wt. 595 390-404 90$ Distilled by wt. 411 400-420 Corrosion Test (6 hrs. at 210C-with bright Change in wt. of Al. Color Condition . Acidity Inorganic Chlorides Aluminum foil) None 45 Clear 0.005 0.1 ppm None 150, max. Clear 0.014, max. NDA Dielectric Constant, 100C, Ike Power Factor, 100C, lkc Resistivity, 100C Dielectric Strength at 25C * Monsanto Stability Test " (16 hrs. .at 210C) 5.8 0 21/o 825 x 10y 55 KV 0.8 ppm 3-6 - 3.8 -------- . 500, min. 30 KV, min. 0.7 ppm, max. Method (b) 1. Aroclor 1232-S Is prepared by chlorinating biphenyl In the presence of FeCl^ and sulfur as catalyst. '_ Typical experimental conditions; Melt 4 kg of biphenyl In convenient size 4-neck flask fitted with stirrer, thermometer, gas inlet and outlet apparatus. Add 20 g FeClj (anhyd. sublimed)* and 11 g of sulfur (flowers)*. I * *A ten-fold excess of catalyst was used here as a precaution against losses due to atmospheric moisture. _ . DSW 440836 STLCOPCB4102550 -7 - Pass in chlorine gas as rapidly as possible maintaining temperature at 100C. Continue chlorination until liquid density reaches 1-280 (25C). ' Pass dry nitrogen through the crude maintaining temper ature at 80 to 90C until HC1 is removed. Add JO g Ca(0H)2 (powdered) and distill through a 6 to 8" dis tilling head, talcing all that comes over. The boiling range is about 1JO to 215/10 mm. ' 2. The Aroclor 12J2-S is then put through a fractional distillation exactly as described in method (a). Method (b) provides us with three advantages as a result of the difference in isomer distribution (Table III). ' TABLE III TYPICAL ISOMER DISTRIBUTION: AROCLOR 12^2 STANDARD 2-ChIoro 4-ChIoro 18$ ' 8$ 2,2'14$ 2,46$ 2,4'- 4,4Trichloro 13$ 9$ TYPICAL ISOMER DISTRIBUTION: 1$ 0 12$ . 1$ AROCLOR 1232-S 44/ 31$ 13f$ The first advantage is flexibility. For example, we can remove essentially all monochlors without greatly increasing trichlors thus eliminating the recycle process. The second advantage is an increase in 2,4'-lsomer con centration. And third, the 2,4-isomer is greatly reduced thus simplifying the fractionation since the 2,4-isomer is the most difficult contaminant to remove. ESTIMATED COST Based on a production volume for Aroclor 1242' of 15 million lbs. per year R. C. Binning has estimated the new distillation facilities would cost $600,000. He has further estimated that for an incre mental sales price of 4.0/ per lb. for Aroclor 1242' a 38$ return on this investment (after taxes) could be realized. J. 0. Bright of Organic Division Research Dept, has also preoared an economic evaluation of the Aroclor 1242r process (Ref. 5") -` The estimate above does not cover the use of FeClj + S catalyst, which should be more favorable. OSW 440837 STLCOPCB4102551 8- - RELATIONSHIP TO EXISTING PROCESS One of the most favorable aspects of the process under discussion is the relatively small change it will cause in the existing process, requiring little more than the installation of the fractional distillation equipment (see Figure 2). Since the new process involves a fractionation the fate of the chlorinated biphenyl byproduct (low Dk dichlors) is of great importance. We feel certain this problem can be handled by the chlorination of the byproducts to higher Aroclors such as 1248, 1254, 1.200 etc. These higher Aroclors are expected to have essentially the same physical properties as the corresponding standard Aroclors. This is borne out by the properties of Aroclor 1260 prepared from the low Dk dichloro byproduct (see Table II). . Also important is the ratio of high Dk dichlors (to be converted to Aroclor 1242') versus the low Dk dichlor byproduct. Assuming optimistically that all of the Aroclor 1242 to be replaced by Aroclor 1242' and all of the low Dk dichloro byproduct to be converted to higher Aroclors, Table IV was constructed to show that a reasonable product balance is possible. Aroclor TABLE IV Yearly Production M Lbs. /based on Aug. 1958 to Apr. 1959 (Ref. 6)J/ Amount of Dichloro _ Reauired M Lbs. 1242 1248 1254 1260 1262 1268 12.6 4.05^ 6.3 7-45 > 0.42 0.15 J 11.0 -' . - 12.4 Product Balance Example (a) . Aroclor 1242' High Dk Dichlor 12.6 M lbs. 11.0 M lbs. Low Dk Dichlor l6.4 M lbs. Example M. 12.6 11.0 14.0 Example Jcl 12.6 11.0 11.0 I qSW 440838 STLCOPCB4102552 -9- The yearly production data (Ref. 6) is based on monthly averages from August 155.3 to April 1559 for both the Anniston_and Vf.G.K. plants. 12.6 M lbs. of Aroclor 1242' requires 11.0 M lbs. of dichloro precursor while all of the remaining higher Aroclors require 12.4 M lbs. Three examples are given under product balance (Table IV) to describe the limits of high Dk dichlor versus low Dk dichlor distribution. Example (A) was actually calculated by R. C. Binning (see Refs. 1 and 2)-based on the composition of current Aroclor 1252 and shows a surplus of low Dk dichlor byproducts. Example (B) was estimated based on the composition of Aroclor 1252-S (see Table III) and the low_Dk dichlors are found to be much closer to the 'ideal' 12.4 M lbs. Example (C) is an estimated lower limit for the production of dichloro byproducts, assuming a lower degree of chlorination to give negligible trichlors. Both (A) and (B) can then be made to approach (C) more closely by a judicious selection of the degree of chlorination and the conditions of recycle of monochlors to recover more of the 2,4' values. PRODUCT Specifications ' Aroclor 12421 - Dkp50 6.7 to 7-2 ASTM pour point -19C . The other properties should be identical to those of standard Aroclor 1242 which are listed here for reference. Density 25 1.580 Distillation range 525-560 Refractive index D-line 20 1.627-1.629 Outstanding Features Aroclor 1242' has a Dk between 6.7 and 72 compared to a Dk of 5-8 for standard Aroclor 1242. MARKETS (This section supplied by J. K. Craver, R&E Development) . .I Based on estimates made by the Organic Development Department, there appears to be a market of from 5-15 million pounds per year for a high dielectric constant fluid to be used in low voltage power-factor correction capacitors. This is in addition to those markets now served by the regular Aroclors and would have to be developed over the next 5-10 years. In addition to satisfactory physical and electrical properties. Organic feel that any new product should be patentable and that the selling price should not be higher than 30//lb. . -- ... . DSW 440839 STLCOPCB4102553 10 The R&3 Patent Department believe that we will have patent coverage on the processes for producing the high Dk Aroclor. A sales price in the range of 19-20p'/lb. would yield 40/o pre tax return according to calculations made by Organic Research (Ref. 5). This estimate assumes the fractional sparation of a pure 2,4'-dichlorodiphenyl isomer which is then chlorinated to a trichlorodiphenyl of high Dk. The lower-boiling chlorinated diphenyls are recycled and the higher-boiling materials are used to produce the conventional Aroclors. Production rates' of 5-15 million pounds per year are assumed. At this price level, we feel the improved Aroclors -described in this report should be of considerable interest to the electrical industry, particularly in low voltage devices. Y.re are aware that there are a number of other new dielectrics being considered by the trade; tolyl xylyl sulfone, 2,21-2d*ic4 h5 6lorodiphenyl ether and hexachlorobutadiene to name three that seem especially' promising, Ho'.vever, the already established position of the Aroclors and their history of reliability, at low cost should make the job of introducing an improved grade much simpler than that of bringing out an entirely new product such as tolyl xylyl sulfone or hexachlruzobuDadlene.. The picture on 2,2'dichlorodiphenyl ether is somewhat more enigmatic since much depends upon the relative costs of the rat; materials. REFERENCES 1. J. S. Harris, "Liquid Dielectrics and Aroclor: A Market Survey", Development Department Report O.D. 1154, August 15, 1956. 2. R. C. Binning, Report to R. W. Schuler on Relative Volatility of Aroclor 1252 Components, Dayton, April 8, 1959* 5. R. C. Binning, Report to R. W. Schuler on Fractionation Requirements for Separation of 2,4'-Dichlorobiphenyl from Aroclor 1252, Dayton, June 5, 1959* 4. A. M. Ellenburg, memo to Harold Y/eingarten on Aroclor 12o0 from Special Process, St. Louis, September 8, 1959- 5. J. 0. Bright, memo to F. B. Zienty, August 5> 1959^ Economic Evaluation of High Dk Aroclors. 6. -A. M. Ellenburg, memo to M. Kosmin on Aroclor Process, St. Louis, June 8, 1959* 7t H. VJelngarten, memo to G. F. Deebel on Preparation of Aroclor 1242' and 1260', Dayton, July 28, 1959* DSW 440840 STLCOPCB4102554 11 8 . H. Weingarten, memo to A. M. Ellenburg, on Compositions of Aroclor 1232 by Catalytic Variations, August 13, 1959. 9 . H. Welngarten, Progress Report on Dielectrics, Issue 23, June, 1959- '. RECOMMENDATIORSFOR FUTURE WORK At Organic Division We recommend that a study be carried out to determine the optimum level of 'dichlorination' and recycle chlorination. The optimum level will, of course, be related to the desired product balance between high Dk dichlors and low Dk dichloro byproduct. We further recommend that the process details be firmed up and moved into the pilot plant stage as soon as possible since there is likely to be a tvjo-year lag between the time we present our customers with samples and the time they complete their evaluations for acceptance. . At R&E Division The pour point of Aroclor 1242 is another property we are anxious to improve while retaining a high Dk. A study of the viscosity of a series of chlorinated biphenyl isomers and the three lower Aroclors (Ref. 9) convinced us that the viscosity and pour point are related to the degree of chlorination and not related to Isomeric structure. We are, therefore. In the process of testing high Dk Aroclors intermediate between 1232 and 1242. Estimated completion time - 3 months. We also plan to finish our chlorination and component studies and examine the possibilities of improving the Aroclors (pour point and Dk) with ether type additives. Estimated completion time - 12 months. . PATENT SITUATION VJe have filed a patent application (C2167) directed to the dielectric composition of matter, the process of preparing same described above as methods (a) and (b), and electrical capacitors employing the new dielectric composition. To date we have not received the first Office action from the Patent Office. I Additionally we have filed a patent application (C2088) directed to high Dk Gomberg chlorinated biphenyls as dielectric composi tions of matter, the method of preparing same, and electrical capacitors utilizing these Gomberg mixtures. The first Office action has been received from the Patent Office and five claims directed to the electrical capacitors have been held to be allowable. 0s\N a40841 STLCOPCB4102555 12 The acknowledged iteras listed below are to be given by the Organic Chemicals Division via memoranda between General Managers to be attached as addenda to each copy of this report. A. Acceptance, reason and data. B. Requirements for and availability of manpower to initiate and carry on the project. : C. Program and time schedule for. further development of the project. bw DSW 440842 STLCOPCB4102556