CA1063275A - Polytetrafluorethylene-polytriketoimidazolidine-solvent coating composition - Google Patents

Abstract

ABSTRACT
The invention provides a high temperature resistant anti-adhesion and slide lacquer composed sub-stantially of finely distributed low molecular polytetra-fluorethylene, a polytriketo-imidazolidine resin and a solvent or solvent mixture. The solvent is an aprotic organic solvent having a surface tension of more than 30 dyn/cm and the solvent is present in an amount by weight of from 0.43 to 100 times that of the resin. The coatings obtained from the coating composition of the invention possess excellent anti-adhesion, smoothing and anti-tack properties comparable with those of pure, also high molecular weight polytetrafluorethylene, high abrasion resistance and resistance to mechanical strain and are still surprisingly tenacious and resistant to deep-drawing.
At the same time, the adhesion of the coating to the substrate is not only equal but superior to that of known polytetra-fluorethylene coatings requiring an adhesive. In addition, no roughening pre-treatment of the substrate is required.

Description

1063275 ~OE 74/~ 907 The present invention provides a ~igh temperature resis-tant anti-adllesion and slide lacquer ("slide lacquer" meai~ing that it has smoothing and anti--tack properties), substantial]y composed of finely distributed lo~ molecl~lar weight polytetra-~luorethylene, a polytriketo~imidaæolidine resin (hereinaftercalled trion resin) and a solvent or solvent mixture.
Coatings of high mole~ular weight polytetra~luoreth.ylene (P~E) are generall,y obt;ained from aqueou~ PT~E dispersions.
Since these coatin~s, because o. the ~own ~ntiadhe~i~e pro-perties o~ PTFE, do not adhere su~icientl~ to the substrate, this substrate has to be pretreated in a suitable manner, for example by sandblasting, and furthermore, adhesi~e substances the ohoice of which depends on the kind of the substrate in question have to be added to the PT~E dispersion. Ho~vever1 this results in a deterioration of the required properties of P'~FE such as æntiadhesive behavior, low coeffici.ent ol vis~
cosity etc. In order to maintain these properties at the sur~-face of tne coatiIlg, a top layer of pure PTl~ containin~
an~, only ver~ small amounts o~ usual additives is coat~d over the a~o~re primer coatin~ Thus, in order to obtain a coating having the desired prope.rties 9 tnese s~rste1ns require three di~ferent oper~tions:
1) pretreatment of` the substrate (~or example sandblasting) ~) coating witl.l a pri~er containin~ a small amount o~ PT~'E and adhesi~Te substances 3) coa~ing ~ith a top l~;er of essential~y p~!re PT~E, ~ urther~iore t aqueo;ls ~Tl~ disper~ ns ilave the lis~d-varltat~eolls ter.denc~ to irre~ersi1~1e coagulation, especiall~r 29 on prolon~ed stor~ge. Such co~.~ulati~n ~ay for ex~2lpie ~ ~ 2 ~

HOE 74/~ 907 already occur by simply agitating a dispersion ~hich ha~ di~
integrated, by mec}lanical strain or b~ storage at elevated temperatures or ten~peratures below the freezing point. Such irreversible coagulation makes the dispersion unserviceable.
In order to o~Tercome these dis~dYanta~es, PT~E cont~ining coatin~s have been alread,y d~veloped which ~void the expensive pretreatment o~ thé substrate and its repeated treatment with primer and top coatin~. It ha~ been tried to o~tain PTFE
ooatings fro~ stable dispersions o~ PTF~ in or~anic solventQ
~laving no tendency to coagulation. Since the properties of the coatings obtained when using this material, especially the adhesion on ~he substrate, are insuf~icient for most appli-cations, these dispersions are mixad with film-for~ing or binder resins, whi~h mixture, however, causes the loss or at least a serious deterioratioll of the excellent allti-adhesion, a.Ati-tack and smoothing properties proper to P~F~ coatings.
It i~ therefore the object o~ the present invention to pro~ide a P~'E containing coa-ting composition in the ~orm of a single-coating s,ystem (i.e. in the for~ of a sy~tem being app-lied to the substrate in one operation only) ~hich is equi-valent or superior to tlle usual double-layer PTFE coatings with respect to anti~adl1esive, smoothing and anti-t,ack behav;for, as ~rell as adhesion to the substrate, aI~d which further~ore has an excellent hardness and abrasiorl resista~lce.
In accordance ~ith the ~resent invention, there is pro ~ided a coating compositioIl s1~bstantial'y ccmlfosed of a) from 10 to 9~ parts by wei~ht of a lo~v molecular weight polyt~tra~luore-th~Jlene ~aving a melt viscosit~r of from 29 10 to l3 poise~ (mea3ured at 3~0C b~r nleans o~ the hig~

- 1063Z75 H0~ 74/' 937 pressure capillary viscometer), a speoi~ic sur~ace of l~om 1 to 40 m2/g (measured accordin~ to the BET method), and a mean particle diameter of fron 0.1 to 50 micron~;
b) from 90 to 10 parts by weight of a pol~mer containi-.~g tri-ketoimidazolidine rings and ~epeatea units Or the formula . O-C =O O-C C=O
` I `I I I .
~ \ / N ---R'- - ~ / N - n where R i~ a mono- to trinuclear, bi- to tetravalent aromatic radical, the arom~tic radicals optionally ~eing al~o quinones, and in pol~nuclear s~stems the aromatic radic~ls optionally being linked b~ aliphatic radicals or hetero atomsS furthermore the aromatic radicals optionall~ being mono- or polysubstituted b~ alkyl, cycloalkyl, alkox~, aryl or ~ono~alent ~unctional radicals, R' is as de~ined for R or an aliphatic or cycloaliphatic hydrocarbon radical, R' optionall~ being interrupted b~
one or ~ore of the following groups:
b1) amide, imide and/or amidoimide groups, obtained ~
introduction of polycarboxylic acids, the ratio of the ~olar equivalents pol~carbox~lic acid : pol~isow cyar.ate being q : (q + 1), and q being fro~ 1 to 40, preferabl~ from 2 to 40;
b21) chelate forming azo or azomethine groups;
b22) metal chelates of such azo or azomethine groups;
the ratio of the molar equivalents o~ the oxamide a.cid ester, used for the preparation of the t~iketo-imidazoli--~ H0~ 74/F 907 dine rings to che'ate-forming agents and/or m~tal chelate3 ~eing (2 to 94) : (0.~ vo 50), and the sum of oxamide acid ester, chelate-forming agent or chelate and possibl~ present polycarboxylic acids always bein~ 100 mol %, n is an integer of ~ro~ o 70, preferabl~ from 1 to 40;
and ! ) an aprot~c ~rganic sol~ent having a surface tension o~ more than 30 dyn/cm, in an a~ount by wei~ht of from 0.43 to 100 times that of com~onent b); up to 80 % of the amount b~
weight of this aprotlc solvent havin~ a surface tension of more than 30 d.yn/cm optionally being replaced b~ another organic solvent not meeting at least one of the two cited requirements, but necessarily h~ving a lower boiling point than the aprotic sol~rent.
The low molecular ~eight P~F~ having a melt vi.sco~it~ of from 101 to 108 poises used as co~ponent a) o~ the coating composition of the invention is a prodv.ct selected from the so-called *luoro-carbon wax series. Such flurocarbon waxes m~y be prepared by thermal degradation of high nolecular PTFE
according to preparation methods known fro~ Ger~an Patent ~o.
1,049,099, U.S. Patent ~o. 2,496,978 and especially fro~
German Of~enlegungsschri~t No. 2,031,046. The latter process is especiælly advantageous, because a su~tal)le adjustment of the pressure allows to direct the p~rolysis to the obtention of products having the desired melt vlsc03i.ty (or the cor~
res~orldin~ rnolecular ~eight range). Also proaucts obtained by means o~ X or gamma ray irradiation according to k~own proce~
ses ma~ ~e useat Such PTFE degradation wa-xes obtained b~ pyro-29 lysis or irradiatioll generally must be ground to a mean ~ H0~ 74/~ 90i particle size of from 1 to 25 microns, pre~erably from 5 to 10 microns before use in the coating ccmposition of the in-vention, since they are often obtained in the form of ~ore or less bulky lumps, which grinding ma~ ~e carried Ollt in a hammer or jet mill.
As component a) of the coatin~ composition according`to the invention, there may be used also a synthetic ~E ~vax obtained according to a known proeess descr~bed in German Of~enelgungsschrift No. 2,235,885, by telomcri~ation of tetra-fluorethylene with a suitable tel.ogene. ~he àqueous dispersions of low molecular PT~E obtained according to this process ~a~
be easily coagulated by means of mechanical forces or electro-lytes to ~orm finely distributed white powders, and they ma~
then be used directly without further pretreatment i~n the coating compositions of the invention.
~y low molecular weight pol~tetrafluoreth~lene being employed as component a) of the coating composition of the invention, there is to be understood a P~E having an apparent melt viscosity of from 101 to 1 o8 ~ pre~erably from 102 to 106 poises at 3~0~ (dete:rmined by means of the high pressure capillar.y viscometer as described below).
Such a lo~;~,nolecular P~ must have furthermore a speci-fic surface o~ Irom 1 to 40, preferably from 4 to 40 m2/g, especially froln 5 to 26 m2/g (measured according to the so-called BET method, see ~runauer, Emmet and Teller, J. Am.
~hem. Soc. 60, 1938, p. 309), and a meal1 particle size of from 0.1 to 50 microns, prefera~ly from G.5 to 20 microns, especiall.y from 1 to 12 microns. ~n the case of a synthetic 29 P~E wax coagul.-lted from the dispers;on , ~ mean partic1e size there is to be under3tood the mean si~e of the primar;y particles.
Component b) of the coatin~ composition of the inventior.
is a so-called "trion resin". By trion resin, therc is to be understood a polymer containin~ triketo-imida~olidine ring~
and repeated units of ~he formula O~ C , r o (~--C-- C=O
I I J I .
~ `-R --~N N ~ T N~
\C/ \ C/
. _ ~ O ,~ _ n _ where R, R' and n`are as defined above.
-Preferabl~, in these trion resin~, the cited s~mbol~ re-present the ~ollowing:
R a bi- or triv~lent phenyl radical ~that is, havin~ tVJo or three radicals capable of bein~ condensed or add~d, see formula IV below), or a binuclear Pxomatic radical. These radicals may bc optionally substituted, ~referably once or twice, by alkyl having preferabl.y fro~ 1 to 6 carbon atom~
(for example methyl, alk~rl? 5 c~rclo~lk.yl or alkylc~Jcloal~rl havin~ preferabl~ fro~n 6 to 12 carbon atoms, ar~rl. prefer-ably phenyl, halo-alkyl, esp~ciall~ fluoroal'.{.yl l~aving preferably from 1 to 5 carbo~ ator.s (for e~ample tr-lfluo~o-met~-~rl), alkoxy ~lavi~lg pr~ferably from 1 to 5 carbon atoms (for exainp1e ~1ethox~r5 etho~.~r), ar~rlox~ ha-~ring pr~ferably frcm 6 ~o 10 carbon atoms, ke'~o&lk~l having preferabJ~ up to 5 carbon ato~s (for exa~ple CX~-CO-) 9 ketoaryl ~aving preferab~ up ~o 1;` carbon at;o~.s, carbox~alkyl having pre~
ferably up to 6 ca-bo~ cato~ , carboxyaryl havin~ preferabl~

H0' 74/~` 307 up to 10 carbon atoms, ester groups h~vin~ p~e~erably up to ~
carbon atoms (~or example ~H~C00- or C2H5-C~0-), al~ylsul~on~l groups ha~ring preferably from 1 to 5 ca~bon ato~ or example C~I3~03-), dialkylamino grouos naving preferabiy up to 6 carbon atoms, diarylamino, pre~erably diphenyla~ino, alkylarylamino havill~ preferabl~ up to 10 carbon atoms, per-~luorinated alkoxy, car~oxyalk~l or acyl havin~ preferably the abovementioned number of carbon atoms, nitro, c~ano or halo~en, especially ~lurlne, chlorine or bromine.
In the case o~ binuclear aromatic radicàls, the phenyl nuclei may be directly condensed one to the ot~ler, that is, form a naph-thyl radical, or they ~ay be linked with each other via a C-~ bridge, such as biphenyl, or they ~ay be linked u~ith each other b~ an aliphatic radical prefe~ab].y having from 1 to 3 carbon atoms, or by hetero atoms 3uGh as oxygen, .sulfur, or b~ hetero atom containing groups such a~
C0, ~2 or NR (R being alkyl having preferably from 1 to 6 carbon atoms, cycloalk~l ha~ing preferably up to 10 carbon ato~s, alkylcycloalkyl ha~Ting pre~erably up to 10 carbon atoms, or aryl ha~-ing preferably from 6 to 10 carbon ~toms, especially ~henyl).
The mono- or binuclear aromatic radicals may also con~
tain hetero-atoms, ~or e~ample they may be thiophene, ben~o-thiophene, benzothlazole, p~ridine, quinoline etc.
Especially preferred for R a.re bivalent aromatic radi~
cals of the ~ormula ~ - ~ X - ~, ) (II) where R" ! iS H or C~-~3, X is 0, S, CH2, S02 or zero, pref~rably 0 or CH2, ls 1 or 2ero, preferably 1, Z i3 fron~ 1 to 3, prefera~ly 1, or - ~ (III) R' of formula (I) is preferably R as cited abo~e or a bivalent aliphatic or cycloaliphatic radical, especially alkylene or cycloalkylene having up to 20, preferably up to 15, espe-cially from 6 to 12 carbon atoms. Examples are methylene, alkylene, propylene, 2,2'-dimethylpropylene, 3-methyl-propyleneg butylene 5 cyclohex,ylene or cyclohexylene sub-s~ituted by lower alkyl ~1 to 6 carbon atom~). Optionally;
these aliphatic or cycloaliphatic radicals may also be substituted by one or more monovalent functional groups, as they are cited abov~ under R, especiall~ trifluoro methyl or nitro or c~rano or halo~en such as fluorine~ chlo-rine or bro~ine.
n of` f'ormula (I) is preferab1y from 1 to 40.
The preparation of such trion resins is described in Ger~lan O~fer.le~lngsschriften `;~os. 1,~20~5 ~nd 2jO30,23 -~OF, 74/~ 907 and it is carried out by reaction of oxamide acid esters o~
the formula R - (N~ - CO - COOR")r (IV) and polyisocyanat,es o~ the formula R~ - (N = C = )s (V).

R and R' o~ t~ese ~ormulae are a~ defined in formula (I);
R'' is a hydrocarbon radical, pre~erably an al~phatic hydro-carbon radical having ~rom 1 to 18 carbon atoms, e~peciall,y from 1 to 6 carbon atoms, a cycloaliphatic or alkyl-cycloaliphatic hydrocarboll radic~ aving from 3 to ~ car~
bon atoms, especiall,y from 6 to 8 carbon atoms, or phen~l, cycloaliphatic/alkylcycloaliphatic hydrocarbon and phenyl optionally being substituted by alkyl radicals each having ~rom 1 to 14, preferably from 1 to 8 carbon atoms;
R" is especia~ly alkyl ha~ring from 1 to 6 carbon atoms1 for example methyl, ethyl, propyl, butyl, i-butyl, n-hex,~Jl;
r is an integer of *rom 2 to 4, pret`erably 2 (bis-oxamide acid ester) and s is an integer of from 2 to 6, preferably from 2 to 4, especially 2 (di-isocyanates).
Suitable pol~isocyanates are for example 2,4,6-tri-isocyanato-t.ol~lene, 4,4',4"-tri-isocyanato-triphenylmethane,

2,454'-tri-isocy`anato-dipllenylmethane, 2,2',5,5' tetraiso-cyanato-diphenyl~ethane, further suitable polyisocyanates (see Ger~an ~ffe~le~ungsschri~t No. 1,920,84.5~
The reaction of the cited oxamide acid esters with the cited polyisocyanates is carried out at temperatu-res of from -10 to ~-280C, preferably f-rom O to 1~0C~ in solutioYl or ~ 10 .- .

106327s HO~ 74/F 907 in the melt, preferably in a so-callea aprotic solvent charac-terized below. ~he reaction may be carried out with or without a catalyst. Suitable catalysts are in principle those normally used also for other reactions of isocyanates ~ith compounds containing reactive hydrogen atoms, such as e~pecially tertiary bases, for example tertiary amines or tertiary phosph~nes, such as triethylamine, tributylamine, ~-isobut~lmorpholine, piperidine, ~-methylpiperidine, N,N-dimethylaniline, trieth~
lenediamine, triphenylphosphine, trimorpholine-p}losphine.
Other cataly~ts are for example lithiu~ methylate or benzoate, sodium ethylate, potaqsium tert.-butylate or organic tin com-pounds such as dibutylstannic oxide, dimethylstannic stearate, dibutylstannic glycolate, dibutylstannic dilaurate, diphenyl-stannic oxide or also ferrocene or metal chelates such as iron acetylacetonate, cobalt complexes; all these cataly~t~ may be _ _.
used individuall~ or in combinations.
The products obtained in these reactions ~hich still con-tain reactive terminal groups are polymerized by further heating to 120 - 550C, preferably to 280 - 450C. By poly-merization there is to be understood in this case a chainlengthening by addition and/or condensation.
~ he molar ratio of oxamide acid ester : polyisocyanate in the reaction is 1 : (0.8 to 2.2), preferably 1 : (0.9 to 1.5) in tha case of equal functionalit.y of both components (r = s). In the case of different functionalit~, this molar ratio has to be varied correspondingl~.
For the exa~ple o~ bis-oxamide acid ester and di-iso-cyanate, the reæction proceeds according to the following 29 general scheD~e:
_ 11 -~IOE 74/F 907 n R"OOC OC ~ R ~H CO COOR" ~ -n OCN ~.' NCO -2~ R"O~
. ~ O=~C=O O-C----C=O
--R ~ ~7, R'-- ~\ N-- (VI) 1 ~ J n ~ he trion resins obtained according to this reaction can be directly employed for the c~ating co~position of the inven-tion with very good results. A ~urther improvement of the advantageous properties is attained when, besideQ the oxamiae a¢id esters and the polyisocyanates, also polyoarboxylic acids are reacted, as described in German Offenlegungsschrift No.
2,030,233, so that polycondensation products are formed which oontain addItior.al amide, imide and/or amidoimide groups.
~ y polycarboxylic acids, there are to be understood carboxylic acids and/or the anh~drides thereof being at least dibasic and no more than hexabasic, preferably no more than tetrabasic, especially di- and tribasic. Advantageously, there are used above all such trion resins the amide,imide or amido-imide group forming components, as described in German Of~en-legungsschrift ~o. 2,303,239, in the form of polycarboxylic acid~ are reacted in a first step with the isocyanate, thus forming a precondensate having free ~CO terminal groups, which precondensate is then reacted with the oxamide acid ester in a second step. The precondensate is formed at temperatures of a maximum of 70C, preferably of from 40 to 60C, and the second step requires temperatures of from 70 to 270C~ pre-ferably from 100 to 220C. A great number of polycarboxylic HOE 74/~ 907 .1063Z75 acids (or their anhydrides) suitable for this reaction are described and proposed in German Offenlegungsschriften ~08.
2,030,233 and 2,303,239, among them ~or example the follo~ing:
isophthalic, trimellitic, pyromellitic, terephthalic, benzo-phenotetracarboxylic, 1,.~,5,8-naphthalenetetracarboxylic, furthermore 2,5-dianilinoterephthalic, 2,5-ditoluodinotereph-thalic, hemimellitic, mellitic, maleic, ~umaric, itaconic, muconic, hexahydroterephthalic, adipic, glutaric, succinic, `sebacic, ~uberic, tetrah~drofuranotetracarboxylic, perylene-tetracarbox~lic acid, the cited acids optionally being sub-st~tuted by chlorine, bromine and/or alkyl groups having up to 6 carbon atoms. SuitabIe are also polycarboxylic acids containing amino groups, for e~ample amide acids optained b~
reaction of maleic anhydride with diamino-diphenylmethane, diamino-dîphenyl ether, diamino-dimethylsulfone, p-phen~lene-diamine or m-phenylenediamine with formation of amide and liberation of a carboxyl group of the maleic anh~dride.
Such dicarbox.ylic acids are preferably used ~or the reaction the carboxyl groups of which are not in ortho-posi-tion and/or such at least trivalent carboxylic acids t~o car~boxyl group~ o~ which at least are in ortho-position, because this ensures the maintenance o~ a high linearit~ of the poly-mer chain.
Suitable polyisocyanates for the precondensation with the polycarboxylic acids are those already mentioned above ~or the reaction with the oxamide acid esters; the di-isoc~anates having radicals R' according to the ~ormulae (IV) and (V) being preferred. Thus, structural anits such as (VII), (VIII), 29 (IX) and (X) (see enclosed formula sheets ), where X, R"', 1063275 ~OE ?4/F_907 and y are as defined in formula (IV), are obtained. Among these structural units, especially suitable are those o~ the for~ulae (IX) and (X), where R"' is H, CH3; X is 0, CH2 and ~ i9 1.
The cited structural units obtained in thi~ manner ma~ be repeated several times within R' (see the reaction product o~
equation VI), in which case they are always linked w'ith each other via amid~, imide or amidoimide group~.
In ¢ase of the same functionalit~ of pol~carbox~ylic acid and polyisocyanate, the ratio of the molar equi~alents should be q : (q + 1), q being at least 1 and at most 40, pre~erably from 2 to 40 and especially frorn 5 to 25. A precondensate is obtained ha~ing isocyanate terminal groups on the one hand, and on the other being of linear structure because of the pre-sence of only one excess isocyanate æroup. In the ca3e of di~ferent functionality of the components the molar ratio~
vary in corresponding and analogous manner.
The properties of the coating composition of the in-vention may be very advantageously improved by incorporating "branching" polycarboxylic acids into the cited precondensate.
Such "branching" polycarboxylic acias may be prepared by con-densation of polycarboxylic acids with other polycarboxylic acids having an amino substituent, that is, for example by condensing trimellitic, trimesic, pyromellitic or benzophenone-tetracarboxylic acid (or the anhydrides therèo~) with 5-amino~
isophthalic or 4-aminoph~halic acid. ~hus, structura1 uni.ts such as (XI), (XII) and (XIII) (see enclosed formula sheet~') are formed, which may be also repeated several times while being linked via amide, imide or amidoimide groups.
29 A ~urther improvement of the properties o~ the coatin~

~063275 H~E 74/F 907 composition of the invention, especially with respect to sto-rage stability and adhesion of the coatings to metal sub-strates, may be attained by introducing chelate-forming azo-methine groups of the formula (HOOC)2 - (Ar) - N = CH - RIV
and/or chelate-forming azo groups of the formula (HOOC)2 - (Ar) - ~ = N _ RV
into the trion resin.
In these iormulae, Ar is an aromatic radical, preferably mono- or binuclear. Furthermore, both carboxyl groups must . .
not be in ortho- or peri-position to each other, and no car-boxyl group should be in ortho-position to the azomethine and/or azo group.
RIV and RV are aromatic or heteroaromatic radicals, pre-ferably mono- or binuclear, and having an OH group in ortho-position to the azomethine or azo group. RI~ and RV may be optionally mono- or polysubstituted~preferably mono- or bi-substituted, by alkyl or monovalent functional radicals ac-cording to the definition gi~en for R.
There are used preferably chelate-forming azo and/or azo-methlne units of the following for~ulae:
COOH COOHand (XI~
Similarly suitable are also the corresponding azomethine and/or azo derivatives of 2-amino- or 3-aminonaphthalenedi-carboxylic acid -(5,7) and of 2-aminonap~thalenedicarboxylic _ 15 , acid -(5,8).
In the above formulae (XIV) and (XV), RIV and RV are a mono- or polynuclear arom~tic or heteroaromatic radical having from 6 to 14 carbon ato~s, preferably from ~ to 10 carbon atoms, containing an O~I group in ortho-position to the azo-methine group, and optionally ~ono- or polysubstituted in the manner indicated under R, ~peciall~ b~ al~yl or cycloalkyl each having up to 6 carbon atoms, furthermore aryl, pre-ferably phenyl, fluroalkyl having prefer~bly from 1 to 6 car-bon atoms, alkox~ h~ving preferabl~ from 1 to 6 carbon atoms, ar~loxy, preferably phenoxy, carboxyalk~l ha~ing preferably from 1 to 6 carbo`n atoms, ketoalkyl having preferably from 1 to 3 carbon atoms, nitro or halogen, preferably fluorine or chlorine; the radicals RIV or RV including all possible ~ubstituents having from 6 to 22, preferably from 6 to 10 carbon atoms.
Suitable azo~ethine compounds are especially the reaction products of 5-aminoisophthalic acid with salicylaldehyde, 1-hydroxy-2-naphthaldehyde, ?-hydroxy-1-naphthaldehyde, 4-methylsalicylaldehyde, 4-carboxyethyl-salicylaldehyde~ 4-methoxy-salicylaldehyde, 3-chloro- or 3-bromQsalicylaldehyde, 4-acetylsalicylaldehyde, 4-hydroxy diphenyl-3-aldehyde, 3-hydroxydiphenyl-4-aldehyde, p-benzylsalicylaldenyde.
Suitable azo compounds are -those obtained by rea.ction of dia~otized 5-aminoisophthalic acid with, for example 9 one of the followin~ co~pounds: p-cresol, 2,4-dimethylphenol~ 2,4-ditert.-butylphenol, p-chlorophenol, 2j4-dichlorophenol, p-hydroxyacetophenone, hydroquinone-monoethyl ether, 1-naphthol, 29 2-naphthol, 4-bromonaphthol, 4-hyaroxyaiphen.yl, 4-h~droxy _ 16 -1063Z75 . HOE 74/F 907 4'-ethoxydiphenyl, 4,4'-dihydroxyaiphenylmethane-monomethyl ether.
The incorporation of such chelate-~or~ine azo and/or azo-methine compounds is described in German Offenlegungsschrift ~o. 2,139,005. These chelate-for~ing compounds may be intro-duced into the chain before or after the reaction with the , oxamide acid ester, optionally in a step~Yise single-vessel reaction. Gen~rally, the components, that is, oxamide`acid ester, chelate-forming agent and, optionally, polycarbox.ylic acid, are dissolved or finely distributed in the solvent, and then the isocyanate in solid, liquid or dissolved form is added at temperature3 of from -20 to 380C, preferabl~ from O to 250~, especially from 50 to 200C. Subsequently, the condensation is carried out at temperatures of from 100 to 250C. In the case of formation of the preconden~ate of poly-carboxylic acid and isocyanate, as proposed in German Offen-legungsschrift No. 2,303,239, the chelate-forming agent may be introduced before or after this ~ormation, advantageously, all three components are reacted together.
The ratio of the molar equivalents of oxamide acid ester to chelate-for~ing azo- or azomethine compounds (or, as de-scribed below, to the chelates thereof) should be (2 to 94) :
(0.1 to 50?, preferably (1 to 80) : { 5 to 20); the sum of oxamide acid ester, chelate-forming agent or chelate and possibly present polycarboxylic acid always being 100 mol ~.
The incorporation o~ the cited structural units, ~hich are dicarboxylic acids capable of forming chelates improves especially the storage stability of the trion resins or trion 29 resin solutions obtained, since these chelate-forming ~roups .

capture traces of metals possibl~ being present.
As also described in German Offenlegungsschrift ~o.
2,1~9,005, it may be advantageous to directl~ incorporate metal chelates of such chelate-forming azo or azomethine groups, which may be carried out b~ reaction with metal compound~. The time of chelate formation may be chosen as desired, that i~, before, during or after the synthesis of the total pol~mer ohain. ~he chelate-forming metal compounds ma~ thus be reacted either together with the chelate-forming azo or azomethine compounds or later. Preformation of the metal chelàtes in a special step i9 also possible, and the chelates may then be introduced into the reaction. The ratio of metal compound~ to chelate-forming agents should be about eq~limolar, preferably slightly less than equirnolar.
Chelate-forming metal compounds ~re for example compounds of metals of the Ist to VIIIth group of the Periodic ~stem capable of forming chelate complexes. Preferabl~, compounds of lithium, sodiuml potassium, zinc, magnesium, barium, aluminum, titanium, lead, chromium, nickel and especially iron, cobalt or copper are used for chelate formation. Especial1~ suitable are the oxides, hydroxides, carbonates, halides, alcoholates, phenolates, acetates, formates or naphthenates. Also complex compounds of such metals, for example of acet~lacetone or of enolized acetoacetic ester are suitable.
~5 The incorporation of such chelate-forming azo or azo-methine compounds into the trion resin as structural u~its is for example shown in formulae (~I) and (XVII~, and that of the chelates in formula (XVIII) (see enclosed forrnula 29 sheets- ).

For the total reaction of oxamide acid ester A', poly-isocyanate ~' and optionally polycarboxylic acid C' and op-tionally chelate-forming agent or chelate D' (when A', ~', C' and D' each represent the number of the moles in question and A' through D' have the same functionality), the ~ollo~ing e~uation is valid:
(A' + ~' ~ D`~ = ~. ~l, where ~ is 0.95 to 1.07, e~pecially 0.98 to 1.02. The poly-i~ocyanate component is preferably used in a sllght excess relative to the three other oomponents. Different functionali-ties of the components have to be taken into consideration correspondingly.
The components of the trion resin, that is oxamide acid ester, polyisocyanate9 polycarboxylic acid, azo or azomethine compound or the ~tal chelate thereof, may be used per se or as a mixture.
Component c) o~ the coating composition of the invention is a solvent in which, on the one hand, the trion resin is readily soluble, and on the other, the low molecular weight PT~E is substantially or completely insoluble. This solvent has to be selected from the group of the so-called aprotic solvents, that is, solvents not containin~ any reactive pro-tons. Furthermores such a solvent should have a surface tension of more than 30 dyn/cm, preferably from 30 to 50 dyn/cm, that is, they should not ~et the low molecular PT~E.
Suitable solvents of this kind are for example N,N'-di-methylformamide, N,N'-dimethylacetamide, dimethylsulfoxide, nitromethane, nitroethane, nitrobenzene, benzonitrile, benzo .
_ 19 -~ ~, . ...

- 1063275 HOE 74/~ 907 phenone, acetophenone~ pyridine, quinoline, methylbenzoate, eth.ylben~oate, 1,1,2,2-tetrabromoethane, 1,1,2,2-tetrachloro-ethane, N,~ hexamethyl-phosphoric acid-trisamide, tetra-methyl urea, tetrameth~lsulfone and, preferably, ~-meth~l-pyrrolidone. It is also possible to use mixtures of suchsolvents.
These aprotic solvents ma~ optionally be replaced b~
other organic solvents in an amount of up to 80 ~, prefera~l.y up to 60 %, especially up to 40 ~p of their total amount, and it is not required that these other organic solvents be apro-tic or have a surface tension of ~ore than 30 d~n/cm at 20C.
However, these other organic solvents must have a lo~Jer boi-ling point than the aprotic solvent used, at least by 10C, preferably by about 30C. Examples of such other organic sol-vents which may be blended with the apr~tic solv-ents used are aromatic h~drocarbons such as benzene, toluene or xylenes, furthermore ketones or esters ~ organic acids such as acetone, methylbutylketone, acetic acid ethyl ester, acetic acid but~l ester and similar solvents. The component c~ solvent, pre-ferably its aprotic a~ount, is advantageo~sly used alreadyfor the preparation of the trion resin, although it is in principle possible to prepare the trion resin in the melt.
Th-~s, the tota; amount of sol~ent, preferably of aprotic sol-vent, may be added alread.y during the preparation of the trion resin, but preferably onl~ a portlon of the solvent is added in an amount which ensures that the trion resin is main-tained in solution. The remaining portiol1 of sol~ent, especi-ally of the other organic solvent, is aaded for dilution pur-29 pQSeS either before the addition of -the fluorocarbon wax . -20 -- 1063275 HOE 74i~ 907 or together with the ~luorocarbon wax, after mixing and homo-genizing, in the form of a paste or suspension; mixing and homogenizing being carried out for example by high-speed ` agitation or on a roll mill. In the ~i.rst case however, the required amount of fluorocarbon wax i~ added in solid form to the solution of the trion resin, in portions and wi~h agitation.
The ratio of fluorocarbon wax component a) to trion resin component b) oP the coating compo~ition of the invention i~
from 90 : 10 to 10 : 90 parts by weight, preferably from 40 : 60 to 70 : 30 parts by weight.
The total amount b.y weight of solvents (comprising the aprotic ~olvent and optionally the other solvent having a lower boiling point), that is, component c),should be 0.43 to 100 times, preferably 1.5 to 10 times, the a~ount of; trion resin contained in the coatin~ composition of the invention (which corresponds to a 70 to 1, preferably 40 to 10 % by weight solution of trion resin).
Additionally, up to 50 weight ~0, preferably from 0.1 to 30 ~veight %, relative to the total amount of low molecular weight PT~E and trion resin a) ~ b), of usual fillers and/or pigments ma.y be addea, such fillers and/or pigments being for example: inorganic oxides such as Al203, TiO2, SiO2, iron oxide, chromium oxide, or sul~ides such as molybdenum sulfide or cadmium sulfide. ~urther examples of such usual fillers and/or pigment3 are ~oot, graphite, cadmium selenide, metal powder or metal alloy powder, for e~ample powdered copper, aluminum or bronze powder. These fillers or pigments may be introduced into the solution of the trion resin in the same 29 manner as described above for the fluorocarbon wax, either 1063Z75 H0~ 74/P ^7 together with the latter or, preferably, separately.
The coating composition of the invention so prepared is ready ~or coating in this form already. Coating may be carried ` out according to known and usual methods, such as dipping, spraying or painting. The coating composition may be applied to surfaces of ~qubstrates having a thermostability dègree which allows them to withstand the subsequent baking process without damage, such as metallic substrates, ~or exa~ple alu-minum or refined steel, or non-metallic substrates, for example ceramic materials (glaæed or unglazed, such às earthenware or china), enamel or glass, but also plastic surfaces.
After being applied to the substrate, the coating layer so obtained is covered automatically by a skin of pure low molecular weight P~E within 8 few minutes only. Subsequently, this coating has to be heated for a short time at a tempera-ture of frcm 320 to 420C, preferably from 340 to 400C, in order to make the low molecular weight P~E on the surface melt to form a film, and to eliminate the solvent. ~his baking optionally causes the polymerization or completion of the polymerization of the trion resin reacted in the first step.
Because of the incorporated trion resins, the coatings obtained f~om the coating composition of the invention possess a number of extraordinarily advantageous properties: excellent antiadhesion, smoothing and antl-tack properties comparable with those of ~ure, also high molecular weight, P~E, high abrasion resistance and resistance to mechanical strain, and still a surprising tenacity and resistance to deep-drawing.
Simultaneously, the adhesion of the coating to the substra~e 29 is not only equal but even superior to that of known P~F-~

1063Z75 ,OE 74/F gO7 coatings requiring an adhesive, and no roughening pretreat~ent of the sub~trate whatsoever is required. It is very surprising that ~hese properties are obtained in a combination of opti-mum values hitherto unknown.
~he abovementioned melt viscosities of the fluorocar'oon waxes are determined as follows: a melt extrusion by means of a high pressure capillary viscometer of Messr~. Gottfert is carried out under the ~ollowing conditions: 3800, 21 kg/cm2 extrusion pressure, nozzle dimensions: diameter 1mm a~d len~th 10 mm. ~he amount of e~truded melt leaving such a nozzle at the given temperature and pressure within the unit of time i5 determined, from which the apparent melt viscosit.y is cal-culated according to the following equation:
. ' ~ , = ~ ;
8 . l . ~l P = extrusion pressure (dyn/cm2) r = radius of nozzle (cm) l = length of nozzle (cm) q = amount oI d~scharged extrusion product (cm3/sec).
The following examples illustrate the invention. In these examples, the adhesion o~ the coatings was tested according to German Industrial Standard DI~ 53 151, the pendulum hard-ness according to DIN 53 157 and the capability for deep-dra~ling according to DI~ 53 156 (~richsen test). ~he cited surface tension data were obtained by measuring according to the so-called bubble bursting ~ethod (surface tension apparatus according to Cassel).
E X A M P L E 1:
A mixture of 99.6 g (0.6 mol) o~ isophthalic acid, 57.8 g - 23 _ 1063275 H03 ~4/~ 907 (0.3 mol) o~ tri~ellitic anhydride, 252 g (1 mol) of 4,4'-di-isocyanato-diphenylmethane and 1 g o~ ~,N'-tetrame-thylhexa-methylenediamine as catalyst, dissolved in 1360 g of N-~eth~l-pyrrolidone, is stirred for 5 hours at 95C. Subseque~itly, 43 g ~0.1 mol) of 4,4'-bis-(etho~al~lamino)~diphenyl~ethane i9 added in portions within one hour to the precondensate o~-tained, and the temperature is raised to 195G. ~en this temperature is attained, agitation is continued for 6 hours.
112 partY by weight o~ N-methylp~rrolidone are added to 100 parts by weight of the tlion resin solution obtained, and sùbsequently, 37 parts by weight of fluorocarbon wax are added in portions with vigorous agitation. This fluorocarbon wa~ is a low molecular PT~3 prepared by a 30 minutes tempering of high molecular PT~3 at 520C and grinding of the reaction pro-duct after cooling in a hammer classifier ~.ill. The mean par-ticle diameter is 6 microns, the melt viscosit~ 2.9 ~ 102 poises at 380C and the specific surface 9.0 m2/g according to BE~.
~he lacquer so obtained is sprayed on aluminum plates by means of a spray gun, and baked for 15 minutes at 150C and subsequently for a further lO minute~ at 360C. The thickness of the coating so obtained is 30 microns.
The adhesion, tested according to the grate cutting method o~ German Industrial Standard DIN 53 151, is evaluated as being ~1 0, that is, the cut edges are entirel~ smooth and - no fragment of the coating is chipped off. ~urthermora J the coating has a endulum hardness of ~5 seconds and and inden-tation according to Erichsen of 6.5 mm. r,lil~ burnt on the 29 coating until it has beccme blacl~ can be removed by a vlater 1063275 HOE 74 jF 907 jet OI a normal waterpipe without leaving any traces.
_X A ~ P ~ E 2:
A suspension of 150 parts of ~-methylpyrrolidone and 50 ` parts of fluorocarbon wax is prepared by means of a high-speed agitator (10 000 rpm). The fluorocarbon wax was prepared according to German OffenlegungsschI~ift ~o. 2,235,885 b~
telomerization of monomer TFE in the presence OI 4 weight %
of ¢hloroform as telogene in an aqueous dispersion. The melt viscosity of this fluorocarbon wax is 7.4 . 103 poises at 380C, the specific surface according to ~EI~ is 19 m2/g, the mean size of the primary particle is 2.0 microns. Furthermore, a trion resin solution is prepared as follo~,vs: 53 g (0.32 mol) oî isophthalic acid, 55 g (O.28 mol) o~ trimellitic anh~dride, 0.5 g of tributylamine as catal~st, 700 g of N-methylp~yrrol-idone and 196g(0.7 mol) of 3,3'-dimethyl-4,4'-di-isoc,ranato-diphenylmethane are stirred for 6 hours at 80C. ~he precon-densate so obtained is reacted for 6 hours at 200C with 43 g (0.1 mol) of 4,4'-bis-(ethoxalylamino)-diphenylmethane, until the separation of C02 has come to an end. 120 parts by weight of the aboYe flu~rocarbon wax suspension are stirred into 100 parts by weight of the trion resin solution. Cooking pans are coated with the composition obtained and baked first for 15 minutes at 150C and then for a further 10 minutes at 400C.
A non-marring and durable coating is obtained which prevents adhesion of îood ~hile cooking. Aluminum plates coated ac-cording to EY~ample 1 have a grate cutting ~ralue OI G~ O, a pendulum hardness of 95 seconds and an indentation according to Erichsen of 4.3 mm.

HOE 74!F 907 E X A M P L E '3:
53 g (0.~2 mol) of isophthalic a~id, ~3 g (0.27 mol) of trimellitic anhydride, 3 g (Q.01 mol) of an azomethine obtained by reaction of 5-amino-isophthalic acid with salicyl-aldehyde, 0.85 g of tributylamlne as catalyst, 196 g (0.7 mol) Or 3,3~-dimethyl 4,4~-di-isocyanato-diphen~lmethane and 700 ~ of N meth~lpyrrolidone arc stirred ~or 6 hours at 80 C. Subsequently, 43 g (0.1 mol) of 4,4~-bis-(ethoxalyl-amino)-diphenylmethane aro stirred into the above mixture.
The temperature is then raised to 195 C, and agitation is continued for a further 6 hours at this temperature. The fluorocarbon wax suspension as described in Example 2 is added to the trion resin solution so obtained in the same weight ratio.
Disks of disk saws are coatod with the coating composi-tion obtained and baked at 350 C. Bubble-free and durable coating~having a thickness of up to 40 microns are obtained which prevent sticking of resin and impart good sliding properties to the disks. Aluminum plates coated according to Example 1 have a grate cutting test result of GT 0, a pendulum hardness of 97 seconds and an indentation according to Erichsen of 4.3 mm.

- 25 a -E X A M P ~ E 4:
. .
A mixture of 41 g (0.55 mol) of isophthalic acid, 58 g (0.3 mol) of trimellitic anh.ydridel 18 g (0.05 mol) o~ the acid imide formed by reaction of trimellitic anh~dride with 5-aminoisophthalic acid, 250 g (1 mol) of 4,4'-di-i~oc~anato diphenylmethane and 1 g N,~'-tetramethylhe~ameth~lenediamine ! as catalyst, dissolved in 1980 g of N-methylp~rrolidone, is stirred for 5 hours at 95C. Subsequently, 43 g (0.1 mol) of 4,4'-bis-(ethoxalylamino)-diphenylmethane are added in portions within one hour, and the temperature is raised to 195C.
After this temperature is attained, the reaction is carried out by further agitation for 6 hours. 90 parts by weight of a suspension containing 24 weight ~0 of fluorocarbon ~ax, 1 weight ~ of soot and 75 weight ~0 of dimethylformamide are added with agitation to 100 parts by ~veight of this trion resin solution. The fluorocarbon wax used was obtained by telomeri-zation (see Example 2) in the presence of 3.5 weight % of chloroform. Its melt`viscosity is 12.5 . 103 poises at 380C, the specific surface 14 m2/g, the mean size of the primary particles 2.4 microns. An aluminum plate coated according to ~xample 1 has a grate cutting test result of GT 0, a pendulum hardness of 1tO seconds and an Erichsen indentation of 3.8 mm.
X A M P ~ ~ 5:
100 parts by weight of the trion resin solution as de-scribed i~ Example 1 are mixed with 112 parts by weignt of dimethylformamide. 35 parts by weight of fluorocarbon wax and 5 parts by weight of iron oxide brown are added to this solution with hi~h-speed agitation. The fluorocarbon wax has 2~ been obtained b~ degradation of high molecular weight - 26 _ disperse P~FE by means of a dose of 5 Mrad of gamma rays. Its melt viscosity is 104 poises at 380C and its specific surface according to B~T is 5.7 m2/g. This lacquer yields red-bro-m coatings havillg good anti-adhesion properties. The results of a coated aluminum plate are the same as in Example 1.
E X A M P ~ E 6- `
-! 252 g (1 mol) of 4,4'-di-isocyanato-diphen~lrnethane and 398 g (1 mol) of 4,4'-bis-(ethoxalylamino)-diphenylmethane are dissolved in 1510 g of N-methylpyrrolidone. Subsequentl~, 3.5 g of dibutylstannic oxide are added as catalyst, and the solution is heated slowly to 205C with agitation. At this temperature, agitation is continued until no ethanol is formed any more.
Furthermore, a sus~ension of 50 g of fluorocarbon wax, 150 g of N-methylpyrrolidone and 50 g of methylethylketone is prepared by means of high-speed agitation (10 000 rpm).
The fluorocarbon wax corres~onds to that of Example 2.
100 parts by weight of the above trion resin solution are biended with 120 parts by weight of the fluorocarbon wax suspension. Aluminum plates coated with this lacquer according to the conditions given in ~xample 1 have a grate cutting test result of G~ 0, a pendulum hardness of 85 seconds and an Erichsen indentation of 2.1 mm. Milk burnt until it has become black may be removed without traces by means of a water jet from a normal waterpipe.
E X A ~ P ~ E 7:
199 g (0.5 mol) of 4,4'-bis-(ethoxalylamino)-diphenyl-methane, 273 g (0~5 mol) of a bis-imide acid prepared by 29 reaction o~ 2 mols of trimelliti~ anhydride ~ith 1 mol of 1063Z75 H0~ 74/F 907 4,4'-diamino-diphenylmethane, and 252 g (1 mol) of di-iso-cyanato-diphenylmethane ~re dissolved in 1680 g of N-methyl-pyrrolidone. ~ubsequently, the whole is heated to 110C witn agitation, and 3.6 g of 1,4-diazabic~clo-~2,2,2]-octane as catalyst are added. The temperature is slowl~ raised to 190C.
Agitation is continued at this temperature, until no C02 and ethanol are fo~med any more.
100 parts b~ weigbt of the trion resin solution so ob-tained are diluted with 50 parts by weight of N-methylpyrroli-done and 30 p~rts by weight of ethyl acetate, and 20 parts by weight of fluorocarbon wax are added in portions with vigo-rous agitation (10 000 rpm). ~he fluorocarbon wax is identical to that of Example 1. According to Example 1, aluminum plates are coated with the lacquer obtained, and the foliowing re-sults are obtained: grate cutting test GT 0, pendulum hard-ness 83 seconds, Erichsen indentation 2.3 mm. Milk burnt un-til it has become black may be removed without traces by means of a water jet from a normal ~aterpipe.
EX A M P ~ ~ 8:
A mixture of 99.6 g (0.6 mol) of isophthalic acid, 57.8 g (0.3 mol) of trimellitic anhydride, 252 g (1 mol) of 4,4' di-isocyanato-diphenylether and 1 g of N,N'-tetramethylhexa methylenediamine as catalyst, dissolved in 1360 g of ~-methylpyrrolidone, are stirred for 5 hours at 95C. Sub-sequently, 40 g (0.1 mol) of bis-(ethoxalylamino)-diphenyl ether are added in portions within one hour to the precon-densate obtained, and the temperature is raised to 195C.
After having attained this temperature, agitation is continued 29 for 6 hours. 100 par-ts by weight of the trion resin so-ution 1063Z75 ~02 74/~ goi 90 obtained are diluted with 150 parts b~ weight o~ N-meth~l-pyrrolidone, and 37 parts by weight of fluorocarbon wax are added with vigorous agitation. ~he fluorocarbQn wa~ corres-ponds to that of Example 1. ~he lacqu~r obtained is applied to aluminum plates and baked as indicated in Exa~ple 1.
~ he adhesion, testes according to the grate cutting test, has a value o~ GT 0. The coating has a pendulum hardness o~
104 seconds and an Erichsen indentation of 7.8 mm. Milk burnt until it has become black may be removed without traces as in - the preceding Examples.
E X A M P L E 9:
53 g (0.32 mol) of i~ophthalic acid, 53 g (0.27 mol) of trimellitic anhydride, 3.1 g (0.01 mol) of an azo compound ob-tained by coupling p-cresol with 3,5-dicarbox.y-phenyldiazonium chloride, 0.85 g of tribut~lamine as catalyst, 196 g`(0.7 mol) of ~,3'-dimethyl-4,4'-di-isocyanato-diphenylmethane and 700 g of dimethylsulfoxide are stirred for 6 hours at 70C. Sub-sequently, 43 g (0.1 mol) of 4,4'-bis-(ethoxal~lamino)-di-phenylmethane are stirred in. The temperature is raised to 155C, and agitation is continued for a further 6 hours at this temperature. ~he trion resin solution so obtained is blen-ded with the fluorocarbon wax suspension described in Example 2 in a ~Jeight ratio of 1:1.
Aluminum plates coated according to Example 1 have the follo- -wing test results: grate cutting l~umb~rG~ 0~ pendulum hardness 95 seconds and Erichsen indentation 3.8 mm. Milk burnt until it has become black is removed without traces as in the preceding Examples.

- 2g -H0~ 74/F 907 ~063Z75 E X A ~ P _ 3 10:
A mixture of 91 g (0.55 mol) of isophthalic acid, 58 g ~0.3 mol) o~ trimellitic anh~dride, 3.5 g (0.01 mol) of azo-methine prepared b~ reaction of 5-aminophthalic acid with 1'-hydrox~-2'-naphthaldeh~de, 250 g ~1 mol) of 4,~'-di-isocyanato-diphenylmethane and 1 g of N,N'-~ètramethylhexameth~lenediamine ! as catal~st, dissolved in 1~8C g of diacetamide, is ~tirred ~or 5 hours at 90C. Subsequentl~, 43 g (0.1 mol) of 4,~'-bis-(ethoxalylamino)-diphen~lmethane are added in portions, and the temperature is raised to 160~. After this temperature i~q attained, the reaction is completed b~ continuing the agitation for a further 6 hours. Subsequentl~, the reaction product is allowed to cool to 80C, and 1.3 g (0.005 mol) of cobalt(II)-acetylacetonate are stirred in. Agitation. is then conti.nued for a further 2 hours at this temperature.
90 parts by weight of a suspension of 20 weight % of fluorocarbon wax, 2 weight ~p of soot, 3 weigllt ,~ of molyb-denum(IV) sulfide (microfine), 40 weight ~0 of di~ethylacet-amide, 10 weight ~0 of N-methylpyrrolidone, 10 weight ~ of toluene and 15 weight ~ of x~lene are added to 100 parts by weight of this trion resin solution. The fluorocarbon wax used is described in Example 4.
~he coatings obtained according to Example 1 usi-ng the lacquer so obtained have a grate cuttin~ test result of C-~ 0, a pendulum hardness of 97 seconds and an ~.richsen indentation of 3.8 mm. ~urnt 1nilk is removed without traces as described above.

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o=l,~,b=o =~ = ~-o z\ o=(~ ~=o oc~ --o o=~ o \ ;~/ \z/

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33 `

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A coating composition comprising:
(a) from 10 to 90 parts by weight of a polytetrafluoroethylene wax having a melt viscosity of from 101 to 108 poises (measured at 380°C by means of the high pressure capillary viscometer), a specific surface of from 1 to 40 m2/g (measured according to the BET method), and a mean particle diameter of from 0.1 to 50 microns;
(b) from 90 to 10 parts by weight of a polymer containing triketo-imidazolidine rings in repeated units of the formula which polymer is prepared by the reaction of an oxamide acid ester of the formula R - (NH - CO - COOR")r and a polyisocyanate of the formula R'-(N=C=O)s in a molar ratio of oxamide acid ester: polyisocyanate of 1:(0.8 to 2.2), calculated on identical functionality of r and s, wherein R is a mono- to trinuclear, bi- to tetravalent aromatic radical, and wherein the aromatic radicals can also be quinones, and in polynuclear systems the aromatic radicals can be linked by aliphatic radicals or hetero atoms, and the aromatic radicals can be mono- or polysubstituted by alkyl, cyclo-alkyl, alkoxy, aryl or monovalent functional radicals, R' is as defined for R
or an aliphatic or cycloaliphatic hydrocarbon radical, R" is a hydrocarbon radical, r is an integer from 2 to 4, s is an integer from 2 to 6, n is an integer of from 1 to 70 and (c) an aprotic organic solvent having a surface tension of more than 30 dyn/cm, in an amount by weight of from 0.43 to 100 times that of component (b); wherein up to 80% of the amount by weight of this aprotic solvent having a surface tension of more than 30 dyn/cm can be replaced by another organic solvent having a lower boiling point than the aprotic solvent.

2. A coating composition as claimed in claim 1, wherein R' in component b) is interrupted by one or more of the following groups:
b1) amide, imide and/or amidoimide groups, obtained by reacting polycarboxylic acids with the oxamide acid esters and poly-isocyanates, the ratio of the molar equivalents polycarboxylic acid: polyisocyanate being q : (q + 1), and q being from 1 to 40;
b21)chelate forming azo or azomethine groups;
b22)metal chelates of such azo or azomethine groups;
whereby the ratio of the molar equivalents of the oxamide acid ester to chelate-forming agents, metal chelates or mixtures thereof being (2 to 94) : (0.1 to 50), and the sum of oxamide acid ester, chelate-forming agent or chelate and possibly present polycarboxylic acids to be reacted with the polyisocyanate are 100 mol %.

3. A coating composition as claimed in claim 1 or claim 2 wherein R is a radical of the formula where Rn' is H or CH3, x is 0, S, CH2, SO2 or zero y is 1 or zero z is from 1 to 3, or

4. A coating composition as claimed in claim 1 or claim 2 wherein component (b) is prepared by the reaction of an oxamide acid ester of the formula R - (NH - CO - COOR")r and a polyisocyanate of the formula R' - (N = C = O)s in a molar ratio of oxamide acid ester: polyisocyanate of 1 :
(0.8 to 2.2), calculated on identical functionality or r and s, R, R' and R" being as defined in claim 1 or claim 2 and r and s are 2.

5. A coating composition as claimed in claim 2 in which the chelate-forming structural unit is an azomethine unit of the formula wherein RIV is a mono- or binuclear aromatic radical having from 6 to 14 carbon atoms containing an OH group in ortho-position to the azomethine group.

6. A coating composition as claimed in claim 2 in which the chelate-forming structural unit is an azo unit of the formula wherein RV is a mono- or binuclear aromatic radical having from 6 to 14 carbon atoms containing an OH group in ortho-position to the azomethine group.

7. A coating composition as claimed in claim 1 or claim 2 in which at least one member of the group of fillers and pigments is present in an amount up to 50 weight percent, relative to components (a) and (b).

8. A process for the coating of a surface in which a coating composition as claimed in claim 1 is applied to the surface and the resulting coating is dried.

9. A process as claimed in claim 8 in which the surface is metal, glass or a ceramic material.

10. A process as claimed in claim 8 in which the coating is dried by heating to a temperature of from 320 to 420°C.