Document gbkqgKLx2o6kLwR22wQOYB8Q

E. I. DU PONT D NEMOURS 6- COMPANY PIGMENTS DEPARTMENT 256 VANDERPOOL STREET NEWARK, NEW JERSEY Serial No. KN-52-12 Copy No. 1 RETURN TO MeKSON LABORATORY FILE ROOM ^ I \* NEWARK PLANT CHEMICAL DIVISION - COLORS (A)GI-727-D, GREEN PIGMENT (CHROMIUM PHOSPHATE) Period Covered November, 1951 - May, 1952 PILE: DATE-. 10/13/52 NJ 5747 Copy tot #1 - Huaerieal File 2 Research Office (210*7) 3 - library PH* (210*7) 4 -- $U Anaoal 5 - J. B* TaUj/JU Siegel f - Extra 8 - Extra Serial Bo. DJ-52-12 Copy *o* i KBttSE FUST pic s ebt mm mmmsB mem > Progress Report mi#l (A) 01-727-0, GRES8 FK3BST Period Covered: Koveasber, 1951 - l&gr, 1952 Charge: A-IIC-287 DUP050069032 tlie outstanding performance of the "Mesh Primer" developed during World Her II has led to considerable effort to produce a single package counterpart* Among the candidates for single package "Wash Primer" is a product pigmented with chromium phosphate* this formulation has aroused enough interest so that the Chemical Division at Hewark was requested to prepare a large sample of this pigment for sampling and evaluation* HISTORICAL During World War XI the Bakelite Division of Union Carbide and Carbon Corporation developed a "Wash Primer", a new chemical coating designed for the protection of the undersides of Naval vessels* this primer designated, "Metal Conditioner WP-1", conilsts of a dispersion of basic sine chromate in a solution of a polyvinal butyral resin, other modifying ingredients, and phosphoric acid* As a metal pretreatment or conditioner it utilizes the physical properties of the resin (i*e* toughness and adhesion) and the chemical reaction of phosphoric acid with steel surfaces to provide a tight adherent bonding surface for subsequent over-coating with other types of finishing materials. This two package system gives excellent performance when properly used hut is subject to certain objections; 1* The primer can only be applied effeotivaLjfc to clean steel* This limits the usage to new construction or surfaces which can be adequately prepared (s*g* sand blasted*)* 2* The primer must be used within about 8 hours of mixing the two solutions since there is a marked loss in its ability to adhere to the substrate on aging beyond that period* 5* Careful mixing of the phosphoric acid component with the pigmented resin dispersion is necessary if a satisfactory product is to be Obtained. Careless ness in this operation has resulted in difficulty in a number of eases * 4* The phosphoric acid component must be stored and shipped in glass containers. 5* This system necessitates the storage of two packages for each' unit of primer. 6* ibis two package system is not satisfactory as a "dipping primer" because of the already mentioned aging effect* In an effort to overcome some or all of these objections the Bakelite Division of the Union Carbide and Carbon Corporation has done considerable work aimed at the development of a single package wash primer tad improvement of such a product, both in their own laboratories and under fellowships sponsored at Mellon Institute* Ghromirst phosphate became of intermit during this work when it was shown to be the best of many substances used for pigmenting such systems* Bis Chemical Division at Hewark was requested to prepare a large Staple of chromium phosphate for testing by Bakelite at Mellon Institute as well as by other interested people* This report covers the work done in the semi-works end in the plant to satisfy- the above request. DUP050069033 -2- This work was aimed simply at making material for sampling, and to see if the product could be manufactured on a plant scale. Ho attempt ha* been made to flM alternate raw materials or make process economies. If it becomes desirable to make chromium phosphate in the plant certainly such work should be undertaken. .4: ' AQI-727-D, chromium phosphate, was prspared for evaluation in a single package wash priaei*. Material was produced in the laboratory* in the semi-works, and in the plant, Heither process nor product has been standardised thus fur. Approximately 2,000 pounds of material was produced during this work and of this amount about half him already been shipped* So far Bakelite has been the only tester to report on hie evaluation. Mellon Institute reports that our product is the best of the commercial samples tested. Initial semi-works preparation of chromiua phosphate was simply a case of enlarging on a laboratorygooses previously developed by Dr* E. B. Denalow. This produet sod process were chosen because the laboratory product had bean tasted mad found to be the best of a number of chromium phosphates prepared in the laboratory* The procedure consists of simply striking a mixed solution of disodium phosphate and sodium bichromate and sulfuric acid into a solution of sodium bisulfite. The "strike" (a simultaneous reduction and precipitation) is made over a period of 20-25 minutes* The net effect of the reactions involved in the strike is exothermic* However, neither Ha the seal-works nor in the plant has this effect oaused any trouble. After the strike, the slurry is stirred for ten minutes and then flooded* The material has been press washed in the semi-works and in the plant* Semi-works washing has bear accomplished in much less time than was required in the plant. Washing of the semi-works material has also been more complete than plant washing. The specific resistance of the semi-works material is therefore higher than that obtained in the plant* The foUowing table susmarizea the lots produced and their conductivity and also the analyzed total sulfate content. Lot 1434 1451 1470 1471 1472 36868* 36874* Where Produced m SW sw SW SW plant plant w* 21,500 9,200 10,000 8,400 8,200 11,000 so,* m 0.95 1.00 1*16 0.63 1.54** 1.47** *lots 36868 and 36874 were struck, pressed and washed as one lot and split for drying study. *#Avsrngs of several sample which showed non uniformity which is thought the result of poor warfling. DUP050069034 these results suggest the advisability of ease vat washing in theplent prior to pressing should this produet be manufactured in the plant in the future. The settling characteristics of the material are such that vat washing should not present any problem unless the vat is allowed to stand unagitated too long. In that ease sa&e difficulty in restarting the agitator night be expected. After pressing and washing the product is drisd in high velocity driers. 140*F. seems to be satisfactory as a drying temperature. the color of the final product is such affected by the drying temperature. Drying at higher temperature (160* - 180*F.) produces a product which is lighter and acre opaque than material dried at a lower temperature (140* - 160*?.). The color appears to be dependent on the degree of hydration and tide product seams to \i6bite water of hydration quite easily. The lump color is very soft in texture and high speed pulverisation may not be necessary. This point has not been studied at all. Sesd-works batch else was 77 pounds and the plant batch size was 1557 pounds (both dry basis). Pressing and washing cycles in the seed-works were short, in fact in the aend-works it was possible to strike* press, wash and load into the drier in an sight hour shift. The pressing tine in the plant was short ( 1-1/2 houri) but the *faf"g cycle was moh longer (16 hours and over) and still the washing was mm* uniform and incomplete. As stated above, it is felt that this situation could bo helped by trying sows amount of vat washing prior to press washing the product. DSH-52-9 S.B.-3389 (48 etc.) SSB-l5i6 3/28/52 SSR-13-9 6/11/52 ELH-51-24 ______mi go future program is planned at this time. When complete results of the various evaluations are Available mors work may be indicated. PATE8T 3TATPS: In our opinion nothing of a patentable nature has resulted from our work. DUP050069035