Document grkK2yXX8Bqz4gvDma8oJ1gq

E. 1. DU PONT DE NEMOURS & COMPANY KREBS PIGMENTS DEPARTMENT 256 YANDERPOOL STREET NEWARK, NEW JERSEY Serial No. KK-52-13 Copy No. 1 ^Numerical Pile NEWARK PLANT PIGMENT COLOR RESEARCH REPORT PROGRESS REPORT HP MILLING OP PHTHA1QCIANINE PIGMENTS - I STUDIES IN ACETONE i Period Covered JUNE, 19^9 - DECEMBER, 1950. 223 A FILE: i" PATE: August 22, 1952 NJT 8747 Copy to: #i.- Sumerical File Research Offlee (223.4} 1:: Library File (223.4) B. F. Kleake Jr., 1 J. H. Tully/A. Siegel I:: Xn. A. Perkinsf m Jaeckson Lab. 2:: J. Olein, Chambers Works I9- 14 Building File .~10 Extra .-11 Extra Serial Ho, KN-52-13 Copy Ho# 1 f NEWARK PLANT PIGMENT COLOR RESEARCH REPORT PROGRESS REPORT TITLE: HF MILLING OF PHTHALOCTAHINB PIGMENTS * I STUDIES IN ACETONE PERIOD COVERED: JUNE 1949 - DEC. 1950 CHARGE: A-II-C-261 s'? ,;T^ BATE SUBMITTED: July 16, 195 b a t e is s u e d : a w s t 22/52, DUP050069018 the summer of 1949* confidential information was received from the Fabrics and Finishes Department that a nas method of dispersing pigments in liquids had been developed, and it was suggested that the meihod might have application in the Pigments Department, particularly in the particle site reduction of phthalocyanine pigments. Two visits were made to the Philadelphia Laboratories of FtF and full information was supplied to the Pigments Department, including sketches and actual inspection of plant equipment and the privilege of reading several reports. Equipment similar to their laboratory equipment was set up at Newark and an extensive program of restarch has resulted* The objectives have been to affect more efficient particle else reduction of phthalocyanine pigments and/or to do it at a lower coat than is possible in the present ball mill operation* \l When this work was undertaken, it waa considered highly confidential and the terminology, *EP Milling", was adopted to distinguish it from any F & F terminology. The issuance of U.S. Patent 2,531,414 (Hockberg to DuPont} has removed any further reason for special secrecy. This report will be largely confined to operations using acetone as the liquid medium* A subsequent report in the.series will cover operations wherein water is the liquid in which the pigment is dispersed* mmjstAjmpromce.ss, considerably mo^dified f#rom that origina,,lly g*iven to us, has been developed fer grinding Phthalocyanine Blue LB and Polychloro phthalocyanine Green in acetone in the laboratory in a cycle of about 1 hour and with a power consumption in the order of 1-1*5 horsepower hour per pound of pigment, which is about 1/3 to 1/2 the power consumption of the Newport ball mills. Partiols else reduction was also obtained with Blue BG, hut a much longer time was required for change to the desired beta phase and this process was not worked out in detail. The process was applied in a limited manner with fair sueeess to certain vat dyea under consideration as pigments. Semi-works studies were also conducted on Blue LB with similar sueeess, as well as limited studies on CPC Green* In spite of the succeseful reduction to practice in the semi works, cost studies did not show s marked having over the ball .mill. process, and it was not possible to justify replacing the ball mills already in operation* The process offered some quality, advantages, but did not eliminate the hasard inherent in the operations with acetone; rather, this hasard would probably be greater, due to a sbmewhat greater difficulty in preventing the escape ofvapors from the mill* The possibility of continuous operation was explored very briefly and is believed to be quite promising, subject to the hasarde inherent in the operations with acetone* DUP050069019 U'.S'f' 2,561,414 (Hockberg to DuPont) cover* the original f & F process, However, the claim* are quite restricted and are limited to a process using Ottawa testing sand* Renee, they do not cover the process as contemplated *t Newark. No other patents are known which will restrict our use of the process. It is believed that there are patentable aspects of the process, both as described in this report and when water is tied as the liquid as will be described in a subsequent report, the following art is known to be pertinent to thie process. Loukomaky (U.S. 2,436,304} obtains bsta phase CPC by subjecting the alpha phase pigment to intensive miking and Shearing attrition in the form of a shSarable magma of pigment and crystallis ing liquid. Although dough miners are specifically dieeloaed, the claims are not eo limited. It might be difficult to write a broad claim around this patent. TJ.S. 2,574,597 and the similar B*nt. Pat, 654,795 (both Celaneae patents) disclose the preparation of a water dispersible dye by milling a paate of the dye wifchwater, a lignin sulfonate and a neutralofalfcaline water Soluble Salt. The claims also include a mean* of directly drying as by spray drying. There is no limitation as to the type of milling. It is planned to file one or more applications of the process and it is hoped that a basis can be found for novelty in the product when ground with water* the application of an intensive shearing action to a tUknSippesnhSSiion in a liqquuiid of a mixture of the pigment and a finely divided inert solid. The inert solid is separated from the pigment suspension end the pigment isolated by conventional means. The equipment uiSd has been similar to that adopted by F & F. The shearing action has been obtained by essentially amooth discs approaching the diameter of the Vessel end operating at fairly high speeds. In the laboratory, a drill press has Served as the source of power, driving s Shaft on which is mounted two smooth stainless steel discs 1/4* thick by 4* di&m. and 1-1/2* apart. They operate in a stainless steel beaker about 5* in diameter mounted with a full length cooling jacket. Speeds up to 2450 RPH have been used. A similar setup was designed for the semi-works using s larger drill pre**, a jacketed 13 gal. container of 14* diameter and two 9* discs at about 900 RPM. This wsi operated successfully, but a more convenient setup was arranged %m*ing the same container, * but applying power through a single 10* disc driven by a Covie* Diaaolver at considerably higher speeds* A larger container, 2t gals, and 19* diameter, has been used with fair Success. The attached sketches show this equipment in more detail. DUP050069020 in the original development by F A F both batch and continuous operations were contemplated, but all plant develop ment used a continuous process in which the coarse sand employed as the inert solid was retained in the grinding vessel by a fine Screen (80-100 mesh) * through which the pigment dispersion passed freely. Retention tins was controlled by tbs rate of withdrawal from a reservoir surrounding the screen. Since eand did not prove to be e satisfactory inert solid for this work and since screen ing was not an acceptable method of removing the solids used for the pignent suspension, the work at Hewark haa all been conducted as a batch operation. In general the desired charge of pigment, liquid and inert solid has bean added to the grinding unit, agitation contained for an arbitrarily chosen time and the whole charge transferred to another vessel in which the mixture was diluted with the grinding liquid, or with water, until the inert solid would settle more rapidly than the finely ground pigment which was removed by decant ation. Since the preferred Inert solids were water soluble salts, final aeparation was effected by solution of the solid in a normal extraction procedure. Acetone removal and final extractions wars done in the manner already developed for acetone milling. DiSCPSSIOS OP vine RESULTS In a process such as this, there are a great many variables which require study and many of them are interdependent. Some of them are purely mechanical, such as the arrangement of the equipment, the speed of agitation and the like, the nature of the inert solid, the proportion of pignant to inert solid, the viscosity of the mixture* the use of dispersing agents and many others of a like nature also required consideration. All of these will be discussed below in an attempted logical Sequence, not necessarily related to the order in which the work was done. the first experiment wasdone in June, l1 i in the Phila delphia Laboratory,, when Jggeeesser#. Horning and Hoebberg of P A F and Stratton of the Pigments department agitated a mixture of CPC LB crude, acetone and Ottawa sand in a 1 qt . can with 2 glass discs for about 1 hour. The satire mixture was brought to Remark, the pigment separated from the sand by dilution and decantation and extracted by the normal procedure {dilute acid followed by ammonia wash). The resulting product had a strength approximately mid-wav between that of the original crude and standard acetone ground CPC BT-284-D. Tills result was considered encouraging, and equipment wee obtained end arranged fer further work at Newark. In almost the first experiment a pair of glass discs obtained from PAP were cracked. They were considered too hasardous for regular use and were placed with 1/4" stainless 'Steel. These were eroded quite badly with sand. Also, with sand, grinding proceeded rather slowly after an initial rapid pick up in Strength. DUP050069021 "4" Finally, the complete removal of sand proved very difficult, if not impossible, and the problem of residual grit loomed very large, it this Juncture, Dr. F. F. Bhrich suggested that.a crystalline sater soluble salt, such as sodium chloride (NaCi), be tried in place of sand, since the ordinary extraction procedures mould remove it without trouble. This proved to have a marked advantage over sand in strength of.'product after a given grinding cycle, and.it' eliminated completely both the residual grit and the erosion of -the .plates. -Mai of other crystalline salt* indicated that the sins of the crystal had more influence than the nature of the salt . in most cases. Thus NH.Cl, Sa2SO^ (NH. )3 ?% and the libs gave more rapid grinding than Uadi. Eventually, pulverised RaCl became the solid of choice because of availability and low coat, coupled with excellent performance. Subsequently, powdered borax (KaoBi-OylOBoO) . .shown to be equally good and the solubility change9 wltl tePBm*ppWeJrTaI ture offered interesting possibilities of recovery which have never been thoroughly explored in the Case of acetone grinding. Is a subsequent report on aqueous grinding will show, borax became the agent of choice with water as the liquid; A few inorganic salts* notably calcium carbonate and sodium carbonate seemed to give markedly inferior results. One attempt to use barytes ae the Inert solid resulted in the surprising observation that separation of pigment and barytes could not be effected under any conditions of dilution* furthermore* there was little evidence of strength develop ment. on- the other hand a very fine sea sand gave results approach ing these from the powdered inorganic salts# very fine steel shot also showed fair performance as to particle site reduction, but the separation and prevention of corrssion appeared very unattractive# She mechanical conditions within the grinding unit proved to be important, as would be expected, but no critical optimum was discovered in any case, anther* these seemed to be important only as they influenced the efficiency of power usage. In general* particle else reduction has proved to be almost a direct function of power consumed, regardless of the equipment * In the $ inch container, discs of 3, 3-1/2 and 4 inches diameter were used with the advantage always in favor of the largest discs. Varying the distance between the discs and the distance from the bottom of the container had only a minor influence on pigment strength* of rotation influence the rate of particle site reduction very mwseue^c*he:e, be--;vu*wt tarsshews Power ycvosnwapu.swawoytyio--1n 'jpp-aessr* - pound of crwlaasgpmwe'esrenevrt-- af#iane.aiwsMwhsemewspd'W remained about the same, thus* higher speeds gave more rapid grind ing at a higher power consumption in terms of time. Jfueh of the work in the ..lab unit -was done at 2450 IF*. The total charge in the unit and ratio of pigment to inert solid have been varied widely but a clear cut optimum has not been established. The larger pigment charges grind more slowly but, again, the power conwamptionpper unit of. color is a major factor. Nevertheless, there appeare to be some point at which the .rate''.per..' DUP050069022 unit of color Buffers. Thia point was not clearly eatabliahed and say vary with the design of the unit . In s similar manner, tbs ratio of color to solid was varied, and there seems to be a rather indefinite point at which the increased time required more than offsets the increased charge possible. The optimum weight ratio varies with the specific gravity of the solid, but the volume ratio has appeared to be fairly constant in the range of IQ to 12 volumes of inert solid (wt/sp gravity} per volume of pigment . The volume of liquid has always been leapt at the minimum required to insure good flow of the charge under the influence of the agitator. Sense work on thinner slurries seemed unfavorable. The laboratory charge *M finally fairly well standardised at 55-60 gm pigment, 1000 gm pulverised NaCl (or 600 gm powdered borax) end about 500 ce acetone. The semi-works charges were close Volume scale-ups of the laboratory chargee. Various dispersing agents were added to determine their effect in the milling operation. No such agent showed any significant or consistent improvement in the rate of grind in acetone. Among the agents tried, may be mentioned sodium bensoate, Triton X-100, Turkey Red Oil and Amiarox A-200. In considering the recovery end re-use of the inert solid grinding aid, it was quickly shown that neither gravity nor centrifugal settling would effect separation st the grinding consistency. Dilution by a factor of 5 to $ was necessary to bring about such separation. To use this much acetone was undesirable to say the least. On the other hand, to dilute with water to this extent meant the lewis of most of the Nad by solution. With borax, on the other hand, it was possible to recover 60$ or more by decantation or by solution, filtration and recrystallisation. However, the use of recovered borax without drying would Introduce a significant amount of water into the system, so a study of the use of dilute acetone of various concentrations was therefore undertaken. The presence of water in such grinds tended always to reduce the efficiency of the milling, but in the range fro 100% acetone to about 50% acetone the loss in efficiency was small. Below 50% acetone, the efficiency dropped off very markedly, so that unsatisfactory results were the rule. 'Rile work, however, led to attempts at grinding crude press cakes. The first such attempt was a semi-works grind of an unusually low kerosene (2-3%) semi-works press cake, and it-resulted in.; edly high strength and rapid grind. However, subsequent work 'with the dry counterpart of this crude indicated superiority over the press eake. Furthermore, the grinding of press cakes with normal kerosene contents (20-30%) was uniformly unsuccessful, and even dry erodes with high kerosene gave poor results in 100% acetone. Apparent* ly dilute acetone can be used only with quite pure crudes. The behavior of many grinds, particularly those with kerosene present. In dilute acetone was very odd, giving the appearance that the pigment had extracted the organic liquid from the mixture and separated ae a pasty mass from the water borax slurry. After this occurred, there was little, if way, further grinding and the peculiar appearance remained through extraction and drying. DUP050069023 -6 A torque table was arranged for one of the laboratory unite and power consumption measurements were made on this device. As expected, the actual power ueage varied with the speed of agitation, but a surprising amount of power we applied to the 2 qt. can in the lab unit* For instance, at 2450 RPH the power required was approximately 0,2 HP. The power consumption per pound of color includes the factor of time of grinding Which also varied with the speed. In these grinds, the rate leveled off after an initial rapid gain, much as it does in a ball mill* however, the time required to approximate standard strength in laboratory grinds was lass than 2 hours at 1250 BPII and less than 1 hour at 2450 RPM. In one series, for instance, 2 hours at 1250 RPM was very close in results to 1 hour at 2450 RPM giving a very dark HT about 10% strong sad Intense vs BT-304-D. The power consumption per lb, of pigment finished at thie level in this series was 1.2*1.5 HP. hre., which compares with over 3 HP. hr. per lb. in the Newport mills. i v, In view of the HP experience, supported by some work on this process toy Qrchem, continuous grinding by the HP process was considered e distinct possibility. Although no attempts have been made to retain tha inorganic salt la the unit with the pigment Slurry passing through a screen, attempts to screen out the solid as a separate operation have been unsuccessful in the absence of sub* stantial dilution. Continuous operation, therefore, is considered possible only through continuous feeding of all ingredients and with drawal of the whole grinding mass for subsequent processing elsewhere. Such a process has not actually been tried, but was simulated by withdrawal of an aliquot sample and replacement with unground crude blue, borax and acetone at fairly short intervals after an initial standard cyole. There was no significant deterioration in quality of such samples over a succession of cycles and it seems reasonable to conclude that a continuous operation of this type would be success ful. later work on aqueous grinding also supports tha belief that a continuous separation of the borax could be worked out. In short, a completely continuous operation seems to be teehaleelly possible, though the economic soundness is questionable. A few isolated experiments of a miscellaneous nature deserve mention. One attempt to use a draft tube, such as now used on mahy processes in the Newark plant, to obtain the desired intensive sheer gave evidence that it was much less effective than the HP unit. No measure of the efficiency in power usage was made, but the operation lacked many of the attractive features of the HP unit and was not pursued further. It has been suggested, but not tried, that tha Abbe Lenart mixer be used in this work. < One experiment using glycerine as the grinding liquid on the theory that high viscosity would promote particle else reduction was not successful. It was suggested that CPC pigment should grind itself DUP050069024 instead of requiring a grinding aid in the form of an inert salt. A sample ground for 7 hours showed no change in strength after the j first few minutes and the maximum change was only of the magnitude to he expected from an additional extraction. 4i Attempts to use a "Syntron* Vibrator to remora the Salt I or borax from the ground slurry were unsuccessful. Large particles | of solid, such as sand, can ba rumored from a liquid with this devlcs, but very small particles do not migrate beyond the pool of I liquid* One attempt to use the HP mill as a salt milling device for "Dispersion Killing9 (salt and a solvent) was partially success-* ful in that there mas a considerable strength increase and some evidence of partial phase change. However, complete fluidisation of the mass was not obtained and there was serious dusting* so it was not an attractive operation* *---------- --Slice li^^y^cMo^S-fres crude 2PC readily available when this wort was done, was a sulfated type comprising a mixture of alpha and beta phases In an indefinite proportion, some phase change was required to obtain a typical Blue BG product. HP grinding with chlorine-free Blue gave normal strength development, but it required several hours (at least 5*6 hours} to obtain any significant phase change; and products of the desired greenness were never obtained. The addition of Perclene to the grinds seriously reduced the strength obtainable. Grinds in kerosene were also quite weak. It is probable that HP grinds of the "BP*1 type crude now available in acetone would give a beta fora product of desirable properties. \ _ work on green was quite limited, but appeared to follow i the principles elaborated above. Attempts to grind a Newport crudefof known poor quality were no more successful than in a ball mill. Some grinds wars successfully mads without an oxidising agent present, but there is insufficient experience to Justify any conclusion on this. vat dye pigments were ground ' mill results which largely conform to the above principles and to the behavior of these same colors in other solvent pilling procedures* "Ponaol" Red SL is a red oxadlasole vat dye which given variable hue in different methods of finishing. HP grinding in acetone gave a bluer* duller hue than other methods and did not slow much promise. "Llthosol* Violet 4 BN Is a vat dye formerly used lithe DUP050069025 CPC in Poeono Slue BP-243-D. It was ground successfully in the HP unit and aerioue consideration Was given to a plant installation for this purpose. However, the potential sales did not Seen to justify the installation and work on this color was dropped. in the seal-works, table suaaarises the data Crow grinds made following notebooks: SB 1190 HB 1191 5 iltl in this report is recorded in the DUP050069026 C Water In fC-- UBOBATOEY OBIT '/Nr~"^c Water out s vs i * ** 7 iI- RBCOftD OF S B C CHARGES weak -m 8 95 100 100 97 99 104 10*93 95 go 4* t2 t tt I uo 8 8 8 8 8 8 8 \ONOi cnO' l NiANO'Hrlto i * 888 t i-ti-Hm *o mmm * * p ooo O'O' & SIS & 8 5Dmm O'O'O' i ifNrHt aiV ^f!o N n HHH J r-l' HNf\ 1 f4, I } I^HHh 'n I r4H HHH 1$ i rllf * i SS <*\ vf\ mcnm g c<v^r<v^>c^rrK^*^<^<^ ^ mcnm 28 9wo~ o 2? 11}! il3* i ilS-8e * * *8 ii \m* 88 dH i p 8 g" S u\ 88 O a O 88 a 2fg. 9 r4 9) e 8 e 8 8 8 8 8 8 8 8 S' 8 s il Cm^v2CH1 HA Hmmrlrmt rt HHrtriHHHtOJArlrt IHH41 a2 JR g SB A 8 88 mmm a. 8 8- 8 43 Ov M <*\ r8 8 888 I 8 . 8 8 8 R 8 8 8 8 8 8 8. 8 8 8 8 8 88 8 8 8 8 888 8 88 Mu m m min. mmmrn*m*mmm trim* mmm 88 2 % 1 gggtttts ss r* \n3 vnt}o**8 o imA'OmCm^'-n8m"O'nCmVQ48 *n3>-A* 'Ai'O IN N Nt-S |3 t`44444-44 4 444 o am tvi* * 8 8 8 &gj,,&5*5* >>>0 >! >>> >>>>> >>> Vo S$ wr Vi" * * s* Pt jl t -8 m' 1 88g S8S8 r>pF> NO H inSr- ). i<nA rtrlHNrl H * H 5 38 . 5 ,,o 8>8 fe '*8 8 8 8 8 te O 8888 miUSnd>i8 M oHn He H8 *!*1 8 8 8 8 8 88 88 8 8. 8 8 8 8 888888 8 8 8 88888888 8. 8 8 888 8 8. 8 SSI S33SS3HH 8Sg lpSfl|l 333 NNNKNWNNNN NNNN NNNNNNNNNNN NNN DUP050069028 s y* . * $3 >|sS: |i *2* * & I f*" 9 St ? S $$$ & 4S0) I f|| r-f r-t <0 1 1 I Jt N H A N rf ' <*V<V <*>tV A n r\ n t\ <*\ S'si Is i || ilryfo i i i:> *> I e i*! l 2g Q If *' * M aB B 4> 8, I * 8 .B _B .B N iJJV rt Hi\ HK\ <ij5 B 88 I I. OI . . 1 Mm l52l1-<nn *auu*ns nr\ v*#\\ <*v\ nvn mn*tnfv vc\\ mnv I g * d >H H 8* ^*.82 lE< |o h. * P* * B B : B B BO. 8 B B B M}8 8 B II 8 B * UN HM H &B B 3 B 8 .. . H S 3 BB B 08 OB B s 8888 v-iISS IS 5B 3 S i UV i*fv. | NW Ci-Ciw N N N (V N N DUP050069029 f HC DUP050069030