Document ybYmQdooodRjMdM4n10vgo8yV

SNDEXED" Mr 9 53 ce G. ft Seidel, !xp* $ta, Wilm* B. a. Brills Hfcwport, D3l j. B* Bullitt, Wilra* B-T016 j Da %mmm 51 p-tois J. Da Boa, " D-8033 R* B* Thos, Newburgh JT* D* Pickens, Flint 0. B, Bullitt, isu, Exp. sta., Wilma j. w* niff, mb,* Russell Morgan^ Dab, R* B. Davis, lab* O, R, B. Merkle, lab Paul Robinson^ Dab* P. B. Evans, lab* k Co impart, Bab* So D* Gcdahalk, Bab* R. L. Selby, Bab S Bochberg, Lab* J. Ho Lowell, Lab D. L. Herndon, Lab* L, P, Hubbueh, lab* Files 1810 Marshall Laboratory March % 1953 MBMORAHDPM REPORT H0 M-555 prepared by; L, P Sermattei tefiaii mn PIC4IBM DEPARIMEM? 9S TlTHALSOPROPfL TOANASB (TFPl imODUQTlOI Messrs* So a* Seidel, J. H Haslam, and H, C. Brill of Pigments Department visited Marshall Laboratory on March a to bring us up to date on the use of tetraisopropyi titanate (OT) for im proving the adhesion of paints to metals, wood, glass .and old painted surfaces* Present at the meeting with the visitors were; P* B Evans 8 L* dodshalk K* C Lamport 0. H, Bullitt, a? B, L* Selby S* Hochberg Co L Evans R. Sm Sheppard P. W* LaBerge S* Graves Miss A Willard H G, Stauffer . <J. P Sermattel N35468 s u mmar y Dr. H. 0* Brill presented the new information on TPT that, has been developed since Pigments5 previous visit last October 2* Dr* Brill stated that their original recommendations for using TPT as a ^ solution in anhydrous isopropanol had not proven satisfactory for practical use. Two percent TPT in isopropanol hydrolyzes too rapidly at relative humidities above %0$, and this results in powdery, non-adherent films that are of no value for improving the adhesion of the coating applied over them. A controlled hydrolysis, despite varying humidity and temperature conditions. Is the key to the successful use of TFT as an adhesion promoting interlayer* fa?* Brill has now established that TPT is effective In Improving adhesion only when; (1) the solvent is evaporated and the TPT film is formed before any hydrolysis occurs, and (2) subsequent hydrolysis of the formed TPT film occurs before the topcoat is applied* The problem has been to devise a TFT composition that complies with' these conditions over a practical range of temperatures and relative humidities* The best composition developed thus far is a solution of 1*8$ TPT and 0,2$ naphthalene in hexane* The naphthalene acts as a hydrolysis suppressor at high humidities while still permitting hydrolysis to occur at low humidities after evaporation of the hexane. The hexane is a very fast evaporating solvent that leaves the film quickly before hydrolysis starts* This composition is effective from 20$ R H. at room temperature to 92$ R* H, at 85P* However, at 20$ R H,, 16 hours at ordinary temperatures are required for hydrolysis to occur to a sufficient extent to produce good adhesion* The procedure for using the TPT/naphthalene solution Is simply to brush or wipe on a thin film of the 2$ solution in hexanes allow to air dry 16 hours, and then apply the topcoat paint. Where baking Is permissible, as In some industrial applications, a bake of thirty minutes at 250R* can be substituted with advantage for the overnight dry* When a latex paint Is applied over the TPT, one to two hours air drying of the TPT is sufficient even under low relative humidities* 7 ACTION . X* K, C, Lampert will run preliminary tests on TPT/ naphthalene for Improving adhesion of trade sales paints to glossy, contaminated paint surfaces*. 2* Stuart Craves will test for improving adhesion to wood of new emulsion paints* 3* R. J* Sheppard will re-examine for improving adhesion of OA to undercoats* DUP030003494 4. R. w. LaBerge will spot check for improving adhesion of outside house paints to wood. 5. P. B Evans will seek clearance for disclosing our QA adhesion problem to Pigments, so as to obtain maximum assistance on the use of TFT, DISSU8SI0H Other.mterials than naphthalene' can be used to protect the TFT from premature hydrolysis, but many* of these fall be cause they stop hydrolysis too completely and thus fail to develop good adhesion. Some hydrolysis of the TPT after :the film is formed is essential. A slight clouding of the TFT film may some times occur on hydrolysis under high humidity conditions and this is not harmful as long as the resulting film Is adherent. Besides providing the proper degree of control on the hydrolysis of TPT, naphthalene dissolves in TFT and solutions of 10$ naphthalene and 90$ TFT are stable. However, with a film former such as OA, it may be &dvan~ tageous to substitute the OA for the naphthalene and us toluene as the solvent for a 2$ TFT/OA solution. In this case, baking the TPT/QA film thirty minutes at 250P* may overcome the erratic results previously obtained under air drying conditions. In this connection, the'Pigments* representatives felt they could be of greater service to us on the OA adhesion problem if we told them what OA was. Most of Dr. Brill *s work has been done over metal and glass and relatively little over wood and old paint. However, he recommended fPT/naphthalene for use over Id paint to improve the adhesion of both latex and oiltype paints, we were cautioned to avoid spillage of the TPT solution on white trim areas as this would cause yellowing. Dr. Brill did not know whether TPT would be effective over gre.ase contaminated surfaces. To be of interest to Trade Sales, TFT should b effective over old paint without sanding or washing? otherwise, there would be no real incentive for using it. Dr. Brill stated that Blchem had successfully used TFT to bond a ceramic coating to aluminum. The TFT bonded ceramic coating withstood a bend around a 1/8" mandrel without cracking. MABSHAX& MBOHATORI j, j. p, s e r ma t t b i JPSsaig 3/4/53 DUP03000: