Document kmyYd2aEqJO61OQ9kQpb9GwNn

Eeperfc MOc R-5T-91 Indexed GGt C W W D, SSseofeald, Lawson# Mil, f 8 ;'))' la Tuna P. B. Cochran, D SCeBuriae^, 8 ')) In Irn E B Davis, J. M Hester, 3 S Allen, m 8m 8? n R E taaa8, lewtrargfe III 1 Mffl&UL. He Wise Esp Station Jo Do Pickens, Flint File s 1665 WOEXED" jm "7 1958 E. lo 611 Pont d Nemours & Compsny, Ine f, & P., Research Division larsliall LahoratesEF r ef er ence copy Research Report / PBE?o%RJITX01 A 8M1L1ZA1101 OF VITOXIMIR CELQBXSB OCTO ACBYL&gB BWB&SI08 COPCagMEBS Data Issued g Period Covered s Project Ho, ; Previous Exportss Notebook Has s 12. 3/37 to .9/5? P-2155 time) lf20, 56-40, 57-23, 5T~33 64-20 Prepares Approved XfiBLE OF ocmsxm / Psg I o Introduction Objectives Smmmrj and Conclusions Action Taken Patent States Discussion A. Selection f Qopol^mr Bo Stabilization of the TOXg/S-BHii (74/26) 'Latex against Maeoloration 0. Stabilization of Xn/2BEA Folyiaes? Fill against on Bzpstxr@e Table 1, List of Stabilizes? Evaluates wltts . WCIq /^SEM (74/86) Table II. Smbrittlessent of TClg/S-SBA. (74/26) Paints s tbs Weatberossetei? Bibliogmpbir 1 1 I. 2 2 3 3 4 7 8 9 DUP030008812 1 PREPARATION & STABILIZATtaW OF H1IYLIBE1E CHLORIDE - OCTfL ACHHATB EMfJLSJQH COPOLYMERS IMEODUCflON: The desirability f obtaining vehicles for emulsion house paints whose properties wer l@ss temperature dependent has been outlined in a previous report (1). Dr. S. if. Fitch (2) has reported the preparation of a epXyser of vinylldeiae ehlride with 2-ethylh$xyl acrylate, containing a. controlled amount f crystallinity, which had excellent initial film properties. Experimental paint made from this copolymer showed early failures by loss ofKintercoat adhesion and extensive flaking. . Clear fils derived from this copolymer, VCXg/S-EEA (74/26), stated an almost complete loss f low temperature elongation, m well, a extensive discoloration, after two weeks exposure on the westheroiieter (3) This. behavior indicated a lack. of stability of tills copolymer towards esgfoswre to ultra-violet light. CBJBCTlfEgs The objectives of this investigation were three in miffibars 1) To determine the feast vinylidene chloride acrylate copolymer based on flexibility - cost eonsideMtions. 2) To obtain adjusts Initial latex color and stability towards pigmentation. 3) To stabilise the latex towards embrittlement on exposure. SUMMARY ASP CCBCLOaiCWS< 1) k cationic emulsion copolymer f vinylidea chloride/ 2-@tS^lhxyXerylt (74/26) was found to have the best balance of properties based on flexibility - cost considerations. 2) Discoloration of tfeeMICio/s-EEft ClV^S) latex prior to pi@a@ntatlx mrom from two'different sources; (a) excessive temperatures during polymerization and monomer stripping and (to) the use of cationic surfactants containing Min nitrogen during synthesis and to stabilise the latex towards pigmentation. For all practical purpose the discoloration aay be eliminated by holding polymerisation and Hsmemer^etrippinsg temperatures' below %0C and by using a non-ionic surfactant" smell as Triton X-100 to stabilise the latex toward pigmentation. DUP03000881 3 3) H staMI.1z t system ms found which would protect p-alists mad from the TCI2/2-KBA {T%/26) latex against loss of elongation on exposure. ACTim TMSMs Slime all f tte attempts to stabilise tills latex, and paints made from it, from severe embrittlement on exposure failed,no. further worle Is contemplated with this system. PA STATUS t Ho patent proposals have been Initiated in reference to the vinylidene chloride copolymer latex paint formulations reported herein. There Is considerable patent art relating to vlnyliden chloride copolymers of wlaiefe many of the patents are assigned to Dow Chemical. Patents which appear to be dominant in the field have expired within the last several year. D.S. Patent 2,160,9^5 which expired June 6, 1956 embraces copolymers .of vinylidene chloride and an alkyl ester f acrylic or methaeryli acid. DUP030008814 DISCUSS!Ms ho Selection of Copolymer Copolymers containing vimylideme chloride as a major constituent were originally investigated because btsis monomer was the only readily available material which mis easily poly merized by frse-radicals, exhibited crystallinity* and Had a low Tg, The effect of crystallinity on the physical properties of a polymer system is discussed in some detail in an earlier report (2). Pitch (2) reported the preparation of a eopolyiaer of vlaylidene ehloride/2-ethylhexyl acrylate (TV26) which had acceptable initial properties* However, because of the relatively high cost of 2-ethylte^yl acrylate it wa of importance to determine if an equally favorable fealasse f properties eouXd be obtained using a less expensive acrylate oiwaos&er. Ethyl acrylate was the comonomer of choice for this study because of its ranch lower cost (roughly half the oost of 2~ethylhexyl acrylate) and ready comsereial availability. A series of copolymers of vinyiideae chloride with ethyl acrylate were prepared and their film properties determined * Mi of the KJlg/kA copolymers were amorphous and showed extremely poor coalescence at room teiperatmre * The films were all xtr@sly brittle. The initial investigation of the Clg/2Bm edpolyawrs (2) had established the optimum concentration of 2~ethylh@xyl acrylate needed in the copolymer for the best balanoe of properties * Since the copolymers of vinylidene chloride with ethyl acrylate had cone of the desired properties it was concluded that the copolymer originally prepared by Fitch (2), VS2^/2-mA (7V26)* Powm@Bd am optimum balance of propertieso B Stabilisation of the Clg/2Em (7^/26) Latex IglSHsfHBSSccEEo^^ Discoloration of this latex prior to pigmentation, was observed and reported by Fitch (2) and was evidenced by the develop ment of a moderate to deep brown color in the latex The causes of this color formation appeared to he two^fold A moderate amount of discoloration resulted from stripping operations designed to remove excess mm&wBT from the latex. J most severe discoloration, however, resulted from attempt to post-tafeili the latex to pigmentation* In the latter instance, color development was so . severe as to preclude the use of the poet-stabilized latex as vehicle for a white paint. DU P030008815 4 The discoloration observed during the preparation and stripping of the latex mn be, for all practical purposes, eliminated by conducting these operations at temperatures below 50*G. Batches of latex prepared and stripped at a maxUsum temperature of 40C consistently showed very little color development even n standing several months. The original batches of latex wem stabilised toward pigmentation by the addition of $0 Ethomeen S/15 (bn polymer solids'.)* fte addition of this wetting agent caused extensive discoloration of the latex and after standing overnight the latex was chocolate bro^m. The addition of ammonia and aslnea caused this sane ' discoloration. to a result of these observations it seemed reasonable to conclude that the color formation was caused by nitrogen-containing compound which probably catalysed the. decom position of the copolymer-*. Post stabilisation of the latex with Triton S-XOOs in place of the Kfchomeen S/lg previously used, effectively Xinfmted this cause of color formation. The remaining small, amount of discoloration which developed on storage of the copolyaser or paints mads fro it could be traced to the ...presence of other nitrogen-oontainlhg cos^omds used in it preparation nd formulation into paints. The only good way to avoid the us of nitrogen-containing emulsifiers and' pigment dispersing agent would be t prepare the copolymer as an anionic latex. C. Stabilisation* of Wl.2/2-Bil (74/g6). Polymer ffilaas .Against Embrittlement on Exposure. --: It is well teem that . heating pelyvinyliden chloride or polyvinyl chloride polymers and copolymers at temperatures of about ?0C find upward will produce a series of selor changes. fee isolation of hydrogen chloride during this reaction suggest that a degradation of the polymer or copolymer has taken place by the removal of chlorine in combination with hydrogen from adjacent carbons yielding a polyene structure, This dehydrochlorlnation could also be catalysed by nitrogen-containing compounds ;suets as ammonia, mine or their derivatives. he presence of the hydrogen chloride appears to favor conjugation of this unsaturation The actual degradation mechanism- is not s clear cut,.-and another type of reaction appear to-take place simultaneously. Absorption speetrn of degraded polyvinyl chloride show strong peak at 2730A which iiis Indicative f the presence of carbonyl groups.. Sties carbonyl groups could very .easily be formed by the oxidation of the polyene structure resulting from the dohydrochlorination of the original polymer. sis oxidation could also promote chain scission and cross-linking. Polyen systems absorb light in the ultra-violet range The energy resulting fro this adsorption will act to r-nf*gis the polymer baits and promote oxidative degradation sn& further DUP030008816 5 del^droohlorlnation Since ultra-violet light is an oxidation catalyst, the oxidation type of degradation is probably predominate during tli light aging life of the vinyl compound* In addition, hydrogen chloride itself definitely catalyses oxidative attack on double bonds under exposure to ultra-violet light (4)* Primary light failure of vinyl chloride or vinylidene chloride type plastics will evidence itself more through embrittle ment; typical of oxidation, with color formation as a secondary failure. From a consideration of the basic chemical reactions Involved In heat and light degradation discussed above, it is possible to postulate the requirements of ah "Ideal" stabiliser5' These requirements are three In numbers 1} Ability to act as a hydrogen chloride acceptor. 2) Ability to act as an antioxidant. 3) Ability to act as an ultra-violet light screen, A ,11st of the materials tested as stabilizers will b found In *le I. Initial screening of the effectiveness of these materials as stabilizer for the TClg/2-EM copolymer latex,under study was aeefispll0!i@d by a modification of a method -described in the recent patent literature (5) Briefly, the.- method e@mi.sts of the pigmentation of the copolymer latex, containing the stabiliser(@) under"test,with ultramarine .blue, and exposure of the pigmented paint (on aluminum panels) fe@ a source ..of ultra-violet light such"'as the Atlas Fadeometer. It has been previously pointed out that ebrittl@ai@jat tmj be associated with the evolution of hydrogen chloride through oxidation f the polyene structures resulting from the dehydrochlorination degradation reaction* t&tramarlne blue is extremely acid sensitive and it is upon this property -that the test depends,, Since the greater the amount of hydrogen chloride liberated during the degradation of the copolymer the greater the degree, of fading observed in the test panel, the method allows the rapid screening of the the efficiency f various stabiliser systems* She panels are easily^rated visually gainst an uspsd control It mas .found that 24 hours exposure -a the ...Atlas Padeosaeter was sufficient t give reproducible results* The isateriaXs listed la Table 1 were evaluated at two levels of Ovinul 400, and visual selection sade of those systems worthy of more.complete valuation* The only three stabiliser systems which did not show extensive fading were -those eontsfning Ferro 541-A, Byphos, and manganese hypoptiosphlte These saterlals, with and without 1$ Winul 400, were then evaluated on their ability t prevent ebrlttlnt of a standard test paint DUP030008817 6 ' wade from the TCio/*EH& (?4/26) latex and exposed to accelerated . weathering on the weatheromet?,, A paint identical t the test paints, except that it contained no added stabiliser sy@t, mu used as a control, Th test paints were formulated on a 3$ PG and 30$ SV basis,. Elongation data were obtained -at TTF on the Xnstron tester after 0$ X, 2*' 3* and 4 weeks espo&ur on the weatheromete? In the usual naaner* Tbm elongation data sr recorded in Sabi 11 (6). Detail of the formulation of tfa paints for both initial screening and final evaluation are recorded la .notebook #6420, On the basis of the result recorded in Table II, it can fee concluded that none of the experimental systems even when used in conjunction with UVinul 400 - was successful la preventing the embrittlement of the test paints upon exposure on the wtherometer; All of the test paint containing the experimental stabiliser systems had less 'elongation than the control paint after one month exposure on the watherait3% ffe explanation can fee offered for the apparent increase In elongation observed after two week exposure on the wssthsroisster; . However, this Increase can not he attributed t the stabilise? systems under test sins the control containing a added stabilisers increased is. elongation a like amount during the same period of time * LSC/hCa 12.-11 DUP030008818 & an HP43 < r3 S"f 88 m & aa If 9 oO HSoif o if j o a 3* a a * .1 A & *8 1 JS o tl H Si a< IS 01 JoM & $ 88 s*J 4$ $> 5SS3 If A oo ss 09 15 HI o S3 v8 1 SB r"3 &* S fos3 33 : *S, ts> a V3 l 3'scv" m w is o n o o 3 w % > o is r*5 m O 2 m s 1 m o- is ^ PS H| 8* 3 <s*s si 3 ii h SH Uh o 3 1 s 43 SI f w4 1 s} 03 1 a I Si * 42 H[ <S IS f? 0Sf & 3s & I fts ^ $ 1 DUP03000881 9 TABES I I * OF tS lg /fe -B II f f i/ 2 6 ) FAim s m 33 H&vHmZuAQI $m 0 *>m553 * < *eS*84A a 1r4* s4 -w 5 g Is n 8 O <rJ H SO 8A H sA rJ a U H t VO smft 0 1 k'-Bc3i .cn &* a o <H 01ft CO ft VOft IVft vs 00 SA V VO Sf 01 m o V ov c CM v oH cn 0*3ft 01ft atf-t &n gw CO h H gw Vffl < CO rv n A s;! as* cn sC Iv 0 4*OS43 * vo cn 0 ft A<ft o CM& Ov 1A c% V V <it* CMft VO V SO *# V j sS* .$ m' 5A m VO gw gI * VCS*" 8 HI J5 4ri Wt so& 03 dv a t* V ' vo 3* VO C\ in 0} co L*- VO m in so IA m VO in VO VO & & Si 8 it H O fA S cn 3* 01 $& a El5* IF*# A 4i 8 8 88 &s- S m<"4 In H- *"l 8 4 t 8 c&r So H S Q 8 a a HHITS:cn **$ H: A 8 P> H a SR 3 r* A s 8 a H A a P> H O i m& a H Q 7 8 cr*nS A s 8 H8 &a i"!}j SU 7 pi ft HI A **a 4 $a P* HI & $ r*a4 04 r*1f 0^s !P| 4 A* DUP030008820 9 (X) R M Pitch# du Font Fms Marshall laboratory Research Report R~57-23 (2) a* M0 Fitch, da Pont F, Harsfeall Laboratory Research import R"5T"33'c (3) L 1, Cuim&ngs, da Posit F&F, Marshall laboratory Exposure Study Results $'. Series #15950, 195? (4) lie L. Scarbrough, *. L 'Kellner, and ?, W,, Rlz^, Modem Plastic, 2, 111 (1952). (5) E. S. Patent #2,773,7^6 t Armstrong Cork Co, 1956. (6) L. H* CtiMiag, da Pont FIsF, Marshall Laboratory Exposure Study Supplement - Series #17082, 1957 General References (1) B. Ho . Jelliaek, Degradation of Vinyl Polymers, Academic Press, in.. ) DUP030008821