Document 2RDj5rwNo6ow8xQqDbx41DXE6

Cl) Resins L2) Mis c . Primers b\ VB-3085 4) 475-1520 CCj J&f , J. ??. Iliff, Philadelphia Mr. C, H, S Merkle, Philadelphia Dr. P. Robinson, Philadelphia Dr. P. B. Evans, Philadelphia.,... Tfl mmmi , ! nIwftr-Mn' mmw imm C- / Flint 2, Michigan November 21, 1947 vjytr^ v -. THE POSSIBILITY OF PAINT CRAWLING DOE TO THE USE OF SILICONE FLUID PHiiAOHLPH * IB NOV 281947 ' ms u f e lAft&RATORY i. an Some time ago it -was found that the addition of a very small amount of JDC-200 silicone fluid to.paints would prevent silking in many cases. Silicone fluid is so successful in preventing silking that it will probably prove to be very useful for this.purpose in many products. This memorandum is being written to point, out that silicone doping may also have its disadvantages, one of which has already been uncovered. - ii. .<aaagM m 11 im Xn some cases where silicon fluid DC-200 is added 'H. ft, 4. to a primer and the primer is baked at a high temperature, a paint film flowed over it may crawl due to the presence of the silicone in the primer. Asphaltic top-coats are especially apt to crawl under such.conditions. Baking the primer at elevated temperatures accentuates crawling as do higher con centrations of the fluid (amounts tested ranged from .001 to .01# on total). While crawling was encountered only in top coats over doped, high-bake primers, film irregularities (ripples) occurred in many systems and in one case with a doped primer even when air-dried. In some cases rippling occurred with top-coats other than asphalts* It is possible that DC-200 can be used in some primers to prevent silking without using so much that crawling of the top-coat is encountered, but it will be necessary to test thoroughly each system into which silicone goes, and to keep the amount of doping below the critical limit for the products involved. The crit-lcal limit will probably vary from system to system depending on the composition of the products in volved and the way in which they are used. N 30760 V ,s%. 2 III, DETAILS Tables are attached showing some specific systems' which have been tested. Table I shows results with dopings about ten times (.01% on total) as great as frequently used to correct silking of the primer. Crawling is encountered in some cases. Table II shows results with an amount (.001$ on total) considered adequate to correct silking in many cases. While this latter doping in these laboratory tests did not cause crawling, there is evidence of film distortion of some kind (ealled rippling) which may be a warning of more serious distortion under adverse conditions. One specific result not included in the tables is of interest. Mr. E. R. Taylor found that YB-3Q35 (baked 5 minutes x 45QF) crawled over 475-1520 (baked .25 minutes x 410F) which contained .0008$ of DC-200. Lower dopings were not tested.since this is the lowest amount which satisfactorily prevents silking of the primer. Higher dopings made crawling worse. In such a system YB-3085 cannot be used over 475-1520 which has been doped with DC-200 to prevent silking, or con versely 475-1520 cannot be doped with DC-200 if VB-3085 must be used over it. FLINT LABORATORY LBDspr DUP030002978 <i *+* }$ TABLE I. 475-1520 .01# DC-200 78-3085 ?jEf&-.US.0SZ 25min, .* 400F 25min. x 400F .OK C 475-6199 w .01# DC-200 AD AD OK si. a 681-1491 25mia, at 400F .01# DC-200 25min, x 4Q0F OK si. C 63-108 -- 25noin. x 400F .01# DC-200 25min. x 400F OK OK 764-1522 - 25min. x 400F ,01# DC-200 25min. x 400F OK C 471-1108 AD OK OK 52-1610 93-3390 ismaisssi a d OK OK R OK OK OK OK , B a a. OK --a -- i --- OK a-- Oft a . C e crawling B rippling (a slightly irregular, rippled surface) DUP030002979 IABLB II 475-6199 475-6199 475-1520 475-1520 475-1520 .001# .001# .001# .001# .005# AD AD SO min. x 2009F SO min. x 200F 60 min. x 300F 60 min. x 300F 25 min. x 4Q0F 25 min. x 400F 25 min. x 400F 471-1076 gomia^g.5,oF. s m 52-1610 23M^x3ml. S si . B $S OK si . S r. si. s si. S s s 7, Si. S Si. 6 s S(worse) S'Ctoorse.) S(worse) 253-51252 OK OK OK ' OK OK OK OK OK OK 6 s silking DUP030002980 ISP o# ,*r ::***4. -' # | DUP030002981