Document B81Jy5xwgVKa0aLBomD6V6BDX

. I. DU PONT DE NEMOURS & COMPANY KREBS PIGMENTS DEPARTMENT 256 VANDERPOOL STREET NEWARK, NEW JERSEY Serial Mo. KN-52-3 Copy No. 1. Humeri cal File K if'S J -3 .. .. NEWARK PLANT PIGMENT COLOR RESEARCH REPORT Final Report ' BEHAVIOR OF COPPER PHTHALOCYANINE PIGMENTS IN PAINT SYSTEMS } IT, ACID PASTED LB AMD SEMICHLOR -FLOCCULATION AND CRYSTAL GROWTH OF THE ALUMINUM BENZOATE LAKES IN LACQUER, Period Covered NOVEMBER 1949 TO DECEMBER 1950 FILE: DATE: 223.4 2-1B-52 Hi 0747 \ DUP050068902 J U S -'/ Copy to: #1 - Numerical File 2 - Research Office (223.4) 3 * Library File (223.4) 4 -J. N. fully t- W. F. Spengeman -A. R. Hanke 7 - Extra S- it Serial Ho. KN-52-3 Copy No* 1. Numerical File NEWARK PUNT PIGMENT COLOR RESEARCH REPORT Final Report BEHAVIOR OF COPPER PHTHALGCTAHISE PIGMENTS IN PAINT SYSTEMS IV. ACID PASTED LB AND 8BMICHLOR -FLOCCULATION AND CRYSTAL GROWTH OF THE ALUMINUM BENZOATE LAKES IN LACQUER* NQVHS8SR 1949 TO DECEMBER 1950 Charge: 1101-11-20 SUBMITTED BY APPROVED BY DATE SUBMITTED: 2-15-52 DATE ISSUE! 2-1S-52 DUP050068903 X. iPPCTIOH In a previous report (KN-51-40), spectrophotonsetric reflectance curves and electron micrographs were used to show that considerable crystal growth of an acid pasted chlorine-free CPC occurred in a lacquer system and that this crystal growth resulted in considerable lose of pigment strength* It has also been previously observed (KN-50-16) that taro other acid pasted CPC pigments containing some chlorine can also become crystalline tinder similar conditions, but the tendency toward crystal growth is less* Previous attempts to associate the Small amount of crystal growth of these pigments with loss in pigment strength have failed because strength changes due to changes in degree of flocculation were always more pronounced and tended to overshadow the strength changes produced by crystal growth alone. This report deals with the attempt to assess the loss in pigment strength, due to crystal growth alone, of an acid pasted semichlor CPC of Orchem manufacture containing 3*30m 01 and a so-called acid fasted LB/CPC of Orchem manufacture containing 3*41$ Cl. In order to accomplish , this, the effect of changes in degree of flocculation is minimised by working with the aluminum benzoate lakes, in which form the flocculation is slight. It should be pointed out that the sample of Orchem*s LB/CPC chosen for this work does not contain as much chlorine as the LB type pigment of Newark manufacture. The Newark type contains around 44$ chlorine* It should also be pointed out that this sample of Orchems semi-chlor CPC contains more chlorine than the average semi-chlor product which runs about 2.9$ 01. This brings the two samples quite close chlorine content and it can be expected that the crystal growing charac teristics of the two pigments will be similar which indeed they are. II. SUMMARY AND CONCLUSIONS 1. Lacquers of aluminum bsnsoate lakes of the acid pasted LS/CPC (3.41$ Cl) and semi-chlor CPC (3*30$ Cl) used for this experiment when stored at 50*0 show a small amount of rapid crystal growth within the first few weeks. 2. The loss in strength brought about by this rapid growth is balanced by a gain in strength brought about by a rapid decrease in flocculation, which tends to keep the strength about the same* If degree of flocculation had remained constant, the crystal growth observed within the first few weeks would have caused a decrease in pigment strength. 3. After the initial rapid crystal growth, there is a slight decrease in pigment strength which is not due to a change in flocculation. The electron micrographe do not clearly show this change as due to crystal growth. It is possible that pigment aggregation is occurring due to changes in the resin solids of the vehicle. To support this contention, it mas observed that as aging progressed, it was increasingly difficult to prepare adequate dispersions for the electron micrographs. 4* The rather rapid decrease in flocculation observed during the first week of aging, and which has been previously observed for other CPC lacquers (see XN-50-18), has been ascribed to the "wetting out" of the paint* Another reasonable explanation is DUP050068904 -2 - that the addition of thinning vehicle after the grind, creates a more compatible balance between solvent and resins and that the establishment of this new equilibrium results in a decrease in the pigment flocculation measurement, there is some simil arity between this phenomenon and "Reactivity". mIII. MaiUieiK[AL A. Preparation ,,of Lacquer ! CPp.. M.^quers the semi-chlor OPC was derived from BK Paste Lot 469 (N-493) containing 3*30$ Cl. the aluminum benzoate lake was prepared according to the normal procedure for BL-282-D (C Process) and a 2820 g sample (158 g dry basis) was used, this yielded 320 grams dry lake, the sample was coded 1285-80. the acid pasted LB/CPC was derived from Orchem*s HDD-1156 Ht* this is a sample of Orchem manufacture made by the solvent (tCB) reaction process using phthalic anhydride and contains 3.41% Cl. the aluminum benaoate lake was prepared from 635 g of pulp (86.8 g dry basis), this yielded 158 g dry lake and the sample was coded 1285-82. Both pigments were micropulveriaed and 27-36 lacquers were prepared according to the following outline{ m2=*b 1285-11 Size of mill 1/3 gal, 1/3 gal. Pigment 90 g. 90 g. Grinding vehicle (K7-36-07) 450 g. 450 g. thinning vehicle (KV-36-tV) 210 g. 210 g. Mixed steel balls (3/16" - 5/8") 1 pt, 1 pt. Grind for 72 hrs. 72 hrs. Strain off balls and obtain yield Mill base yield 64? g 617 g Add KV-36-TV 358 g 341 g Mix and store in 1 gal. cans. this gave a pigmentation of 7.73# in each case. 2. ti02 Lacquer the white pigment used for extensions was "ti-Pure" R-610 grade, two 1 gal. grinds were prepared according to the following outline. -J-- Size of mill Pigment (R-610) Grinding vehicle (KV-36-GV) Porox balls (3/8") Grind for Strain off balls and obtain yield Mill base yield Add thinning vehicle (K7-36-tV) 1 gal. 708 g 1350 g 1 qt. 72 hrs. 1 gal. 708 g 1350 g 1 qt. 72 hrs. 4060 g 3700 g Mix and split into 2 equal portions Store in two 1 gal. cans. this gave a pigmentation of 18. WK. DUP050068905 -3 the two, one gel* cane containing each type of CPC were stored in an oven at 50*C (122F) for a period of 1 year. The cans of TiOg lacquer were stored at room temperature* From time to time, the cane were removed from the oven and 10/90 extensions (toner basis) were made using the Ti<>2 lacquer. Since the TiOg lacquer was stored in two cans, one can was always used for semi-chlor extensions and the other can for LB extensions. Before opening, the cans were first shaken for 10 min. to 30 min. in a shaking device manufactured by the Miracle Paint Rejuvenator Co. The cans were then opened and the lacquer inspected for uniformity by manipulation with a spatula. Good uniformity was always found* To make the extensions, a 3S.S gram portion of the CPC lacquer was mixed with a 75 g portion of the white lacquer. This gave a 10/90 toner basis extension (20/90 on lake basis). The mixing was accomplished by first stirring with a "Lightnin" mixer for 15 min. and then shaking for 15 min. on the "Rejuvenator". This assured a uniform lacquer and an unchanging composition of the lacquer In the can, which meant reasonable duplication of the degree of extension. Early experiments had shown the need for such treatment in achieving the necessary uniformity for the kind of teats subsequently made* These extensions were thinned to spraying consistency with T-3601 (Is I by volume). Primed aluminum panels 3" x 7" were sprayed in the conventional manner. An attempt was made to keep spraying conditions reasonably constant throughout the experiment* After the sprayed panel had dried, a portion of the spatula-stirred thinned lacquer was poured over the panel, covering approximately 1/3 to 1/2 of the panel. The panel was then tipped on edge and the excess lacquer allowed to drain off. This is the conventional practice for making the so-called "pour out" test. This surface was then allowed to dry* C. Light Reflectance Curves A Q.E. self-recording spectrophotometer was used. The reflee* tancs was recorded relative to the Rational Bureau of Standard Vitrolite White. All reflectance measurements were made exclusive of the specular beam. On the G.E. instrument, this is accomplished by inserting black velvet cups in the integrating sphere. The complete curve from 400 n\a a to 700 pt* was obtained for all panels but for calculations, only the reflectance at 465 p* and 616 jpu was used. These reflectances were cor rected to a MgO white basis using the conversion factors supplied by the Bureau of Standards. Curves were obtained for both the sprayed portion and the poured portion of the panel. D. Conversion of Reflectance flurves to Flocculation and Crystal SsEIai 1- Measurement, PQiSCSSlft&lon For the measurement of flocculation, the spectrophotometrlc curves of both the sprayed and the poured portions of the panel were used. If no flocculation existed, both surfaces would yield the same curve and DUP050068906 -4- the flocculation index would he aero. If crystal growth had occurred, it would not become a part of the flocculation measurement because the crystal else would be the same for both the sprayed portion and the poured portion. If a flocculation difference existed, the flocculation index 4 b was calculated from the following equation, the development of which is explained in KN-50-15: Ab - 30 A b * a term which increases in magnitude when there is a relative increase in average ITirftliocclecuelaiatieo,ni.n this case an increase 30 estimate of the constant slope of the straight line obtained by plotting *pi, as ordinate and <p 2 as abscissa for a series of extensions. 1 the difference in $1 values derived at a wave-length of 465' 9M between the sprayed and poured surfaces. yp2* the difference in $2 values derived at a wavelength of 616 sjA between the same two colored surfaces. Notes The subtraction of values of the two colored surfaces to obtain A<p was always made poured minus sprayed. where R is the reflectance exclusive of the specular reflectance and corrected to MgO white as the refer ence white. The following is a typical calculation using data derived from the epectrophotometric curves of one of the panels. i PANEL SURFACE Poured Sprayed mbjwmj&wttm. mmm,, msMM,' ... % Rj % R%^Gorr.) fj ..1,6^6,, tR2 ^(Corr 59.6 59.6 52.0 52.0 4.46 10.3 4.46 9.0 0.00 Notes A b 30 A<t>2 * A&1 Ab - 30 (0.032)-0 Ab 0.96 A..large value indicates- considerable flocculation, 'i low value m DUP050068907 Note:(Cont*d) means very little flocculation. In this case 0.96 means a low but significant amount of flocculation. 2. With age of the lacquer, the appearance of the spray##': portion of the $102 extension changed. Both flocculation and crystal growth:can be responsible for this change. With an aluminum benzoate lake, however, the flocculation is small and if crystal growth is large . most of the change with age can be attributed to crystal growth, this is the case with the add pasted chlorine-free CPO described in KN-51-40. In the case of acid pasted LB and semi-chlor UPC, crystal growth is not large, hence if it is shown that flocculation is increasing with time it will be difficult to say whether the change is due to crystal growth or flocculation or both. In other words, an index sensitive to crystal Srowth alone is not possible with measurements described in this report, ince the index measuring crystal growth is also sensitive to flocculation it will be called the crystal growth-flocculation composite index. Such an index is still useful in those cases where it can be shown that floc culation is decreasing and the composite index is increasing. In such a case, the increase cannot be due to flocculation. The composite index uses the same function as the flocculation index but instead of comparing a sprayed with a poured surface as is done in the flocculation index, the surface of an aged lacquer is com pared with the surface of a fresh lacquer. To distinguish the index from the flocculation index, .it will be called A c and the equation becomes Ac 30 Acp - A<p 1 where Afti is derived from the "aged* measurement minus the "initial" measurement at 465 m/A and A$ 2 is derived from the aged measurement minus the initial measurement at 616 ma/A The following is a typical calculation from data derived from spectrophotometric curves of the panels. SPRAYED SURPACE mummj&mmmjmsm A- 1*65 mM %% (Corr.) ^ \ 616 mM jfeg jK^(Gorr. I ^2 3 wks. 59.6 aged lacquer Initial 60.3 lacquer 52.0 52.5 4,40 9.0 kM. --0,10 9.0 7.04 7*04 0.105 0.105 0.000 A c 30 A^2 - A<f>x ..... - Note: Ac - 30(o) + 0.10 Ac * + 0.10 A large positive value indicate# considerable composite crystal growth and flocculation. In this case. + 0.10 is so small that DUP050068908 -6- Note:(Coat'd) it is of doubtful significance and may be within the experimental error* E. .Bate Both the flocculation and the crystal growth-flocculation composite data are recorded in Table 1* TlmelVeeks) 0 1 2 3 zi 52 TABLE 1 fioSoK6' lation Flocculation -late- 2.20 0.81 1.02 0.96 1.23 1.01 1.52 0 0.03 -0.12 0.18 0.03 0.61 1.07 --4-CI0.FA Floccu lation Flocculation .JMag, Composite Index 1.98 1.08 1.20 1.23 1.44 2.13 1.65 Note: By sero time in column 1 is meant the time at which the pigment has been ground into the vehicle. Since the grinding time ie 72 hrs., it is in reality already 3 days old if reckoned from the time the vehicle touched the pigment. At sero time therefore, some crystal growth has already occurred. The composite index has ths numerical value of sero for sero time because the difference is reckoned from the sero time curve. The data of Table 1 are plotted in Figure X. i-lagtroP^Micrograpla At the time the TiO? extensions were made to obtain spectrophotometric curves, electron micrographs were also obtained of the unex tended lacquer. These are illustrated in Figures 2 through 11. They will he discussed in greater detail in the next section* Fig. 2 3 4 5 6 Plate 1189 1192 1202 1340 1424 ACID PASTED LB HASSTONB LACQUER ------------------------------------------- _ 1 week 5 weeks 6 months 1 year DUP050068909 Fig. 7 6 9 10 11 -7- SEMI-CHLOR MASSTOHB LACQUER Plait te t udd 1193 1201 1339 1423 1 week 5 weeks 6 months 1 year IV, GBRSRAL DISCUSSION y tw Two indices have been defined (see Section III-D) based on light reflectance curves. The first index, the flocculation index, is based on the difference between the curve appearance of a sprayed and poured lacquer surface. The seemingly complicated method of expressing the index is justified because when so expressed it is insensitive to small changes in ratio of CPC to TiC^. This makes unnecessary extreme precision in making extensions for comparison purposes. Unfortunately this index is not completely insensitive to factors other than changes in flocculation of the CPC, It is probably somewhat sensitive to changes in flocculation of TiQ2* With regards to flooding, it is reasonably insensitive to changes in ratio of CPC to Ti02 brought about through flooding but if the flooding mechanism causes a separation of fine particles from course particles as well as a cMhgs in pigment ratio, the magnitude of the index will be affected* At best, it must be recognized that the index measures a composite of several factors but these self-same factors are also included in our visual In terpretation of flocculation. In other words, "flocculation* is fairly rigidly defined as "the formation of clusters of particles separable by weak forces" but our visual interpretation of a flocculated system also includes the phenomena of "floating", "flooding", and "pigment separation*. This "flocculation index" takes a step in the direction of achieving some separation of these other phenomena but tha separation ia by no means complete. Recognizing that other factors do have sums effect on the magnitude of the index, for the sake of simplicity,, it Will still be called a "flocculation" index. The second index utilized in this report is the so-called "crystal growth-flocculation composite" index. It is also derived through comparison of two colored surfaces but, in this case, the colored sur faces are an initial and an aged surface. This index ie calculated in the same manner as the "flocculation* index and like it, is relatively insensitive to small changes in the ratio of CPC to Ti02* This index is the closest approach to a separation between the effects of flocculation and crystal growth that can be made with the data of this report. When flocculation is low, this index reflects the effect of crystal growth. For the data of this report, the flocculation is low because we are dealing with aluminum benzoate lakes but it is also true that for the pigments studied, crystal growth is also low and hence both the factor of flocculation and of crystal growth must be considered when dealing with this second index. DUP050068910 -0- B- P^taj:nfcerpretati,.o Fig. 1 shows that the tendency towards flocculation of these aluminum benzoate lakes falls off during the early aging period of the lacquer. After a few weeks, there is a reversal and following that a tendency for the flocculation curve to level off . this is exactly the pattern followed by the toners and reported in KN-50-10. Another observation to make is that as flocculation is decreasing during the early aging period of the first few weeks, the composite measurement of crystal growth and flocculation remains about the same* It has previously been observed for crystal stable CPO (KN-50-10) that a decrease in flocculation would cause a decrease in this composite measurement but it is during this early aging period that crystal growth is occurring* See Figures 2, 3, 4, & 7, o, 9. In fact, the electron micrographs show that in the case of the semi-chlor CPC, crystal growth has occurred during grinding and the crystals are clearly evident in the initial lacquer. This will tend to decrease pigment strength and the actual > c value will be the result of these two opposing conditions. During the later aging portion of the curve, the extent of flocculation is no longer changing rapidly, whereas pigment strength is still falling off to soma extent. This would indicate continued crystal growth but such growth is not clearly evident from the electron micrographs. See Figures 2 through 11. These micrographs show that after an initial period of crystal growth, further growth is extremely slow. That crystal growth is responsible for the loss in strength during the later aging period must be considered with doubt, A form of aggregation may be responsible and it was noted that good dispersions for electron micro graphs were more difficult to obtain with aged lacquers than with fresh lacquers. V. PATENT SITUATION No action is planned. VI. FUTURE PROGRAM This is the final report in the series of four reports and no further work is contemplated. lg DUP050068911 C ry s ta l Growth F lo c c u la tio n Composite In d e x (& c) (0 ) F lo ccu la tio n Index (hb) (X) Figure 1 Change in Flocculation and Crystal Growth Acid Pasted Semi-chlor Acid Pasted LB DUP050068912 Figure 2. Initial Acid Pasted LB Masstone Lacquer DUP050068913 Figure 3 Acid Pasted LB Masstone Lacquer Aged 1 Week at 50 C a* * 3,500 X DUP050068914 Figure 4 * Acid Pasted LB Masstone Lacquer Aged 5 Weeks at 50C DUP050068915 Pasted LB Masstone Lacquer Aged 6 Months at 50C DUP050068916 6. Acid Pasted LB Masstone Lacquer Aged 1 Tear at 50C DUP05Q068917 Figure 7* initial Acid Pasted Semi-chlor Masstone Lacquer Plate 1183 3,500 X DUP050068918 Figure 8. Acid Pasted Semi-chlor Masstone Lacquer Aged 1 Week at 50C Plate 1193 m ^ -ah* * * * #* ?. Twr^ 'W,. 3,500 X DUP050068919 Figure 9. Acid Pasted Semi-chlor Masstone Lacquer Aged 5 Weeks at 500 DUP050068920 Plate 1339 3,500 I DUP050068921 Figure 11. Acid Pasted Semi-chlor Masstone Lacquer Aged 1 Year at 50G DUP050068922