Document MM6Zypn9MMvvbkjnekLa3bdqL

E. I. DU PONT DE NEMOURS & COMPANY KREBS PIGMENTS DEPARTMENT 256 VANDERPOOL STREET NEWARK, NEW JERSEY Copy No. KH-44-21 / l ibr ar y c o py Period Covered: NEWARK PLANT PIGMENT COLOR RESEARCH REPORT Progress Report By-Product Medluia Chrome Yellow from Zlac Yellow Backwater - K-1980 Laboratory sod Devolopment Studies January 15 - February 29, 1944 FILE: DATE. 211 a 4/11/44 N39988 Copy to* #1 - Numerical File 2 - Research Office (211.1) 3 - Library Pile (211.1) 4 - #10 Building File 5-#6 6*7 -. Imperial Chewmical Indusntries. Ltd. g_ B B 9 - Mr* C. B. Rupprecht/I,CI. File Serial No. 0-44-21 Copy Bo. i SEWARK PLANT PIGMENT COLOR RESEARCH REPORT Progress Report Titles By-Product Medium Chrome Yellow from Zinc Yellow Backwater - K-1980 Laboratory and Development Studies Period Covered: January 15 - February 29 1944 SUBMITTED BE: APPROVED BY: E. C. Botti -c. r3dri4t. C. Chalupski DATE SUBMITTED: 3/13/44 . /y, /fY. DATE ISSUED: 4/11/44 N39988.01 DUP050150334 -2 ira(mmoa fh soluble chromate present in zinc yellow backwater has been utilized in the preparation of a by-product medium chrome yellow* The original K-1967 formula, as set up by the Development Laboratory, made use of I-539-D backwaters con taining approximately 0*039 lbs. of CrOj per gallon. Color obtained with this process was darker, duller, weaker and very poor in lightfastness against 7-469*0. -1930, which Is & replacement for -1967, introduces alum in the formula to lighten the masstone and improve the lightfastness. Color so produced is being consumed in standard mixes of 7-424-0* There is very little that can be done to improve the strength because of the large quantities of soluble salts in the backwater, especially chlorides. Since the quality of a by-product chrome yellow depends on having the proper proportions of ingredients, it is absolutely essential that a representative sample of the zinc yellow back waters be obtained and carefully analyzed for SaaCroOv.aSoO. Then for every 100 lbs, of Sa2Cr207*2&2 tiie strike vat, the following quantities of raw materials are used; Lead Nitrate Alum "L* Liquor Soda Ash 208# 25.3 as is 2.04 3a. 00 Development Laboratory studies showed that adjusting the pB after strike to 6.1, without further treatment, gave dark, dull products of distinctly inferior lightfastness. Beat development to 150F resulted in a lighter, redder, more intense masstone, weaker and redder tint and a small Improvement in lightfastness. A marked improvement in lightfastness was obtained with an "L* Liquor (l) treatment after the heat development period. Further Improvement was made possible by an alum addition before the *L" Liquor. This latter treatment also resulted in a lighter, more intense masstone and increased strength. Sodium silicate (8-91), in addition to alum and "Lfl Liquor, had no effect on tinctorial properties. A 60 minute stir after heat development gave slightly weaker material of improved lightfastness. Sub stitution of alum for *L* Liquor was also tried but the masstone and lightfastness suffered, especially the latter. Attempts to effect savings in steam consumption, by allowing the color to settle after the strike, drawing approximately 2/3 of the supernatant liquid and then heat developing etc} resulted in a dark and green masstone. DUP050150335 -3- Precipitation of th excess chromate after heat develop ment by lead nitrate solution, resulted in a redder, more Intense and weaker color. If Instead, the lead nitrate was added after a 60 minute stir (following the heat development) them, there were no tinctorial differences. Increased yields were obtained In both oases. In the plant, care must be taken by the operator in measuring the number of Inches of sine yellow backwater In the strike vat* This measurement is very important since sub sequent Ingredient calculations are based on the total amount of BaoCr2O7.2820 present in the vat. The strike solutions are not adjusted to definite pH*s or temperatures. The pH of the back water has varied from 6.3 to 7.0-and the lead nitrate from 2.2 to . 3.2; these large differences in pH affect the pH after strike considerably, l.e., 3.2 to 6.0. The present plant formula has a calculated 6$ chrome excess, but eves with such a safety factor, several batches have ended up with a lead excess after strike. When this happens, sodium chromate should be added immediately to a slight chrome excess, otherwise, dirty material results. Plant batches were neither vat washed nor press washed and this may account for the poor lithographic bleed observed In Ink tests. Press washing of plant slurry in the laboratory has always given darker and duller masstones. A batch which was stirred for 60 minutes after heat development "flopped" to a very red shade and was very weak. This variable had been tried successfully in the laboratory with a resultant improvement in lightfastness of the product. The yields have been high, 102 to 105# of theoretical, and may be due to the presenoe of soluble salts In the color. The aotual filtrate volume per batch of T-539-D Is approximately 1650 gallons and contains from 0.033 to 0.039 lbs./ gallon Cr03 which is equivalent to 81-96 lbs. of available sodium chromate per batch. Actual performance with makeshift press room equipment for collecting backwaters has given approximately 75-85# recovery of the chromate. Steps have already been taken to Insure a more efficient recovery of back water in the future. BXPERIM1BTAL DBTAIX.8: tm - 44-2 KS-43-11 DUP050150336