CA1238826A

CA1238826A - Flexible basecoat/clearcoat coating compositions

Info

Publication number: CA1238826A
Application number: CA000464871A
Authority: CA
Inventors: Delores J. Alexander; Kenneth R. Kurple; Panagiotis I. Kordomenos
Original assignee: Ford Motor Company of Canada Ltd
Current assignee: Ford Motor Company of Canada Ltd
Priority date: 1983-10-13
Filing date: 1984-10-05
Publication date: 1988-07-05
Also published as: EP0138587A2; EP0138587B1; DE3464628D1; EP0138587A3; US4533704A

Abstract

Abstract of the Disclosure This invention is directed to flexible basecoat/clearcoat coating systems which have excellent adherence to metal and plastic substrates and possess superior weathering properties. The clearcoat composition comprises hydroxy-containing urethane modified polyester, made by reacting a urethane modified diol with polyol and diacid component, crosslinkable with amine-aldehydes. The basecoat composition comprises hydroxy-containing urethane modified polyesters, made by reacting hydroxy functional polyester with diisocyanate, crosslinkable with amine-aldehyde and pigment. Optionally, either or both compositions may comprise a high molecular weight linear polyurethane.

Description

~Z3~326 FLEXI~LE BASECOAT/CLEARCOAT COATING COMPOSITIONS

This invention relates to flexible basecoat/clearcoat coating systems which have excellent adherence to metal and plastic substrates and posse~a superior wea~hering propertieR. Basecoat/clearcoat sy~teme comprise a finish of a clearcoat top layer in film adherence to a basecoat that i~ in adherence to ~ubstr~te. More particularly, the invention relates to basecoat/clearcoat coating composition~ which comprise 10 hydroxy-containing urethane modified polyester, amine-aldehyde crosslinker, and, optionally, a high molecular weight linear polyure~hane. The hydroxy-containing urethane modified polyesters of the pigmented basecoat are made by reacting polyester polyol resins with isocyanate, while the novel hydroxy-containing urethane modified polyesters of the clearcoat are made fro~
urethane modified diols reacted with polyol and dlacid co~ponent.
Recently, there has been interest in the use of rubbery resilient materials for areas which are subject to mechanical shock such as automobile bumpers, moldings and front ends. The use of such materials aids in providing protection from permanent structural damage but, in order to attain the desired appearance, a protective coating must have unique properties, such as a high degree of extensibility, impact resistance, resistance to cracking under severe environmental conditions, such as exposure to low temperature and low humidLty. Conventional coatings, including those employed on rubber and slmilar extensible objects heretofore, do not have the required combination of properties. Generally compositions that are flexlble enough to be applied over both metal and plastic subetrate~
have rather poor weatherability and overall durability.
U.S. Patent 3,8~2,189 and U.S. Patent 3,962,522 are exemplary of numerous patents which describe flexible coating compositions wherein the resin comprises polyurethane modified polyesters formed by reacting polyisocyanate with polyester polyols. These resins are cured with amine aldehyde crosslinkers. It is taught therein, that the presence of the urethane group~ in the polymer significantly contributes to the flexibility as well as improved weathering properties, gloss, and abrasion resistance of the coating. However, while it is thus desirable to employ a substantial number of urethane groups ln these res1ns, the amount which may be included in these types of re~ins is limited. When hydroxy polyester re~in is re~cted w1th polyisocyanate it has a tendency to foem a gelled mass and thus the amount of polyl~ocyanate that may be employed must be restricted in order to avoid gelation.
Still further, these urethane linkages are added in a latter modification of the polyester polyol reaction product, rather than being incorporated into the backbone of the resin.
This invention ia directed to flexible basecoat/clearcoat coating compositions which are suitable for use over various sub~trates. The compositions may be used over rubbery, resilient materials as well as ovec metal. The basecoat/clearcoat coating composition of this invention is characterized in that:

~;~3~38;2~, I the clearcoat composition co~priRes:
(A) hydroxy-containing urethane modified polye~ter (i) having a number average molecular weight (Mn) of between about 1000 and about 10,000, (ii) having a S hydroxyl number of between about 30 and about 200, and (iii) containing between about 1 and about 10 urethane groups per molecule, and being made from reactant~
comprieing:

~1) urethane modified diol made by reacting:
(a) diol, and ~b) dii socyana te, wherein the diol and diisocyanate are reacted in a molar ratio of from about 4:1 to about 4:3;

(2) polyol comprising at least about 5 weight percent triol; and ~3) acid component selected from dicarboxylic acids and anhydrldes thereof~ and (B) amine-aldehyde cros~linking agent; and II the basecoat composition comprises:

(A) hydroxyl-containing urethane modified polye~ter ( i~ having a number average molecular weight (Mn) of between about 1000 and about 10,000, (ii) having a hydroxyl number of between about 50 and about 250, and (iii) containing between about 1 and about 7 urethane groups per molecule, and being made from reactants comprising:

(1) hydroxy functional polyester prepared from a mixture oE (a) polyhydroxy material~ comprising diols and triols with (b) acid component selected feom dicarboxylic acids and anhydride~ thereof;
and 1~3~

(2) dii~ocyanate;
wherein in focming the hydroxyl functional polye4ter, the proportion of reactants (a) and (b) are selected so that the O~/COOH ratio is from about 6:2 to about 6:5; and wherein in forming the rnodified polyeRter~ the proportion of hydroxy functional polyester (1) and the diisocyanate (2) are selected ~o as to provide from about 4:1 to about 10:1 hydroxyl/isocyanate groups;

(B) amine-aldehyde crosslinking agent; and (C) pigment.

Preferably, the polyhydroxy materials (a) comprl~e the diols and triol~ in a hydroxyl equivalent ratio of from about 4:1 to about 1:4, more preferably ttlis ratlo is from about 3:1 to about 3:2.5.
The basecoat compoaition and ~he clearcoat composition may optionally individually comprise up to about 60 weight percent, based on the total welght of (A~
and (B) of each composition, of a linear polyurethane having a number average molecular weight of between about lS,000 and about 40,000, preferably of between about 20,000 and about 30,000.
Advantageously, the flexible ba~ecoat/clearcoat coating co~position4 of the inYention of thia application possess superior weathering properties as well as excellent adhesion to metal and plastic, thus making them well r~uited for use as coatings on variou~ car componer)t~. Most particularly, these improved weathering properties are a result of the clearcoat composi.tions of the 30 basecoat/clearcoat coating composi~ion of thia application.
In forming the hydroxy-containing urethane modified polyester of the clearcoat, the urethane linkages are advantageously incorporated into the backbone of the modified polyester, since they are formed in an initial reaction of diisocyanate with the diol, rather than being incorporated into the polyester in a later reaction step as i8 done when forming prior art urethane polyester resins.
It has now been found that the initial incorporation of the urethane linkage into the backbone of the modified polyester allows the formation of more flexible coating~
with improved weathering properties, particularly suitable to form automotive basecoat/clearcoat coatings.
Still further, the ability to use of the same coating compositions on metal and plastic components in car production offe~s di~tinct commerc~al advantage~, 15 partlculacly ln terms of productlon efficiency.
Addltionally, because these coating~ can be employed on metal aB well a8 plastlc components, the problem of color matching, which must be resolved when u~lng a different coatlng on the metal and pla~tic, is eliminated.
This invention is directed to flexible basecoat/clearcoat coating compositions which comprise hydroxy-containing urethane modified polyester cros~linkable with amine-aldehyde crosslinking agent. The hydroxy-containing urethane modified polyesters of the ba8ecoat are made by reacting polyester polyol resins with with isocyanate, while the hydroxy-containing urethane modified polyesters of the clearcoat are made from urethane modified diols reacted with polyol and diacid component.
~ither or both of the basecoat and clearcoat compo~ition 30 may optionally include a high molecular weight linear polyurethane. The various components of the basecoat co~po~itlon and the clearcoat composition will be discussed in detail.

38;26 The hydroxy-containing urethane modified polyester of the clearcoat coating composition of this invention has a number average molecular weight (Prn) of between about 1000 and about 10,000, preferably between about 2000 and about 4000. This modified polyester has a hydroxy number of between about 30 and about 200, preferably between about 50 and about 120. It also contains between about 1 and about 10 urethane groups per molecule. One of the reactant~ used to form the hydroxy-containing urethane modified clearcoat polyester is a urethane modified diol which i8 made by reacting diol and diisocyanate. In forming this urethane modified diol, the dlol and th~
dlisocyanate are reacted in a molar ratio of from about 4:1 to about 4:3, preferably in a molar ratio of from about 2:0.8 to about 2:1.2, most preEerably in about a 2:1 molar ratio. The diols employed in making the urethane modified diol include, but are not limited to, alkylene glycols, such as butylene glycol, neopentyl glycol, 1,5,pentene glycol, 3-cyclohexene~ dimethynol, and other glycols such as hydrogenated bisphenol A, caprolactone diol (i.e., the reaction product of caprolactone and ethylene glycol3, hydroxy alkylated bisphenols, polyether glycols, e.g., poly~oxytetramethylene) glycol, polyester diols, e.g., 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxy-propionate, and the like. Preferred diols are neopentylglycol and 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-

3-hydroxy-propionate, the latter material being commercially available as Esterdiol 204 ~a trademark of and available from Union Carbide Corp., New York, N.Y.). While a number of types of diols have been mentioned above a~
~uitable for use as the diol component in making the urethane modified diol of this invention, their disclosure is not meant to be limiting. A great many diols are known in the art. Selection of other diol~ which would be ~2;~ 6 -- 7 ~

suitable for use in forming the urethane modified diol would be well within the skill of those in the art.
Mixtures of diols may also be employed in making the urethane modified diol.
The diisocyante employed in making the urethane modified diol may be essentially any diisocyanate. Many such otganic diisocyanates are known in the art. Suitable diisocyanates include hydrocarbon dilsocyanate or substituted hydrocarbon diisocyanate, such as 1,6-hexamethylene dilsocyanate, lsophorone dii~ocyanate, p phenylene diisocyanate, biphenyl dii~ocyanate, toluenc diisocyanate, and 3,3-dimethyl-4,4-biphenylene diisocyanate. While the diiqocyanate may be any of a number of aliphatic, cycloaliphatic, and aromatic diisocyanates, it is preferred that the diisocyanate be an aliphatic diisocyanate, such as 4,4-dicyclohexylmethane-diisocyanate. As would be apparent to those skilled in the a~t, mixtures of variou~ diisocyanates may al~o be employed at the dlisocyanate component used in forming the urethane-modifying diol.
The polyol component used in forming the hydroxy-containing urethane modified polyester of the clearcoat comprises at least about 5 weight percent ttiol (based on the weight of the polyol component). Preferred triol~ are conventional low molecular triol~ such as 1,2,6-hexene triol, l,l,l-trimet~lylol propane, pentaerythritol, 3-~2-hydroxy-propoxy)-1,2-propanediol and polycaprolactone triols, which are commercially available as, for example,PCP-301 (trademark, Union Carbide Corp., New York, N.Y.). This polyol component may also comprise, ~23B82~

in addition to the triols, other polyol materials such as diols or tetrols. Preferably, however, these other polyols, when employed, consist of diols. Examples of suitable diols which may be included in the polyol S component are those whlch have been disclosed above as ~uitable for forming the urethane modified diol of the clearcoat. Preferred diols for use in the polyol component are linear aliphatic type dlols. Whlle the polyol component may comprise materials such as diol~ in ~dditlon to the triol~, ~he polyol component may consist essentially of triols. By employing diols in the polyol component in addition to the triols the flexibility of the coating composition is generally increased. ~hus selection of the polyol component to be used in forming the hydroxy-contalning urethane modified polyester of the clearcoat will be dependent on the particular desired properties and application of the coating compor;ition.
- When diols are employed in the polyol component, the polyol preferably comprises from about 10 to about ~0 weight percent triols and from ahout 90 to about 20 weight percent diols.
The acid component which i8 used to form the modified polyeriter of the clearcoat comprises aliphatic, aromatic, cycloaliphalic dicarboxylic acids or anhydrides thereof. Preferred dicarboxylic acids are the C6 - C12 acids, which include adipic, azelaic, sebasic, or dodecane dicarboxylic acid, or cyclohexanedicarboxylic acid More preferably, the dicarboxylic acids employed are aliphatic dicarboxylic acids, most preferably additionally being linear. Mixtures of suitable acids and/or their anhydride~
may also be used as the acid component in this invention.

~ ~3~826 g _ In forming the clearcoat coating compositions of this invention, the diol (a) and the diisocyanate (b) described above are combined and ceacted, generally at an elevated temperature, so as to form the urethane modified diol. The ratio of the diol to diisocyanate (i.e., a molar excess of diol) ha~ been chosen so that at the completion of this reactlon no free isocyanates are present, having been incorpoeated into a hydroxy functional m~terial. This urethane modified diol is then combined and reacted with the polyol and acid components,generally in the presence of a catalyst and at elevated temperatures, 80 as to effect formation of a hydroxy-containing urethane modified polyester. Suitable cataly~ts for the carboxy/hydroxy condensation reaction include such catalysts a~
tetraisopropyl titanate, strong acids such as p-toluene sulfonic acid, phosphoric acid, sulfuc1c acid and materials ~uch aa zinc oxide, antimony oxide (Sb203) and sodium acetate. Other catalysts will be apparent to those ~killed in the art.
The hydroxy-containing urethane modified polye~ter of the basecoat coating composition has a number average molecular weight (Mn) of between about l,OOO and about lO,OOO, preferably between about 2000 and about 4000. This modified polyester has a hydroxy number of between about 50 and about 250. It al~o contains between about 1 and about 7 urethane groups per molecule. This modified polyester 18 made from hydroxy functional polyester and diisocyanate reacted in such propoetions so as to provide from about 4 to about lO hydroxyl groups per isocyanate group. The hydroxy functional polyester i~ made from a mixture of ~a) polyhydroxy materials comprising diols and triols with (b) acid component selected from dicarboxylic acid~ and anhydrides thereof. The proportion of reactants (a) and (b) ate selected so that the OH/COOH ratio is from about 6:2 to about 6:5. Preferably, t~e polyhydroxy materials comprise diols and triols in a hydroxyl equivalent ratio from about 4:1 to about 1:4, more preferably from about 3:1 to about 3:2.5. By hydroxyl eguivalent ratio ia meant the r~tio of the hydroxyl equivalent6 of the diol to the hydroxyl equivalents of the triol.
The diols, triols, acid components and diigocyanateS which are employed in forming the hydroxy-containing urethane modified polyestee of the ba ecoat may be selected from ~uch materials described above for making the hydroxy-containing urethane modified polyester of the clearcoat. In forming the lS hydroxy-containing urethane modified polyestee of the basecoat, the polyhydroxy materials (i.e., diols, triols and optionally tetrols, etc.) and acid component reactants are combined and reacted, generally at elevated temperatures and in the presence of a catalyst, ~o a~ to effect foemation of the hydroxy functional polyester.
Catalysts for the carboxyl/hydroxy condensation reaction are well known in the art. Exemplary of such carboxyl/hydroxy catalysts are those which have been disclosed above for use in the clearcoa~ formulation. This hydroxy functional polyester is then modified by reaction with the diisocyanate, whereby urethane groups are incorporated into the polyester.
The reactions, whereby the hydroxy-containing urethane modified polyester of the ba~ecoat or clearcoat are formed, are generally carried out in the presence of solvents commonly employed for coating formulations such a~
toluene, xylene, methyl amyl ketone, etc.

123~82~

Another eqsential component of the coatlng compositions (basecoat and clearcoat) of this invention i8 an amlne-aldehyde croqslinklng agent. ~nlne-aldehyde crosslinking agents suitable for crosslinking hydroxy functional bearing material~ are well known in the art.
Typically, the~e crosslinklng materlals are product of reactions of melamlneJ or urea with formaldehyde and VaeiGu~ alcohols containing up to and including 4 carbon atoms. Preferably, the amine-aldehyde crosslinking agents useful in this invention are amine-aldehyde re6ins ~uch as the condensation products of formaldehyde with melamine, ~ubstituted melamine, urea, benzoguanamine or substituted benzoguanamine. Preferred members of this class are methylated melamine-formaldehyde resins such as hexamethoxymethylmelamine. The particularly preferred croeslinkers are the high solids melamine resins which have substantially 100 percent nonvolatile content as measured by the foil method at 45C for 45 minutes. For the purposes of the preferred composition of thia invention it should be recognized that it is important not to introduce extraneous diluents that lower the final solids content of the coating. Other suitable amine-aldehyde crosslinking agents will be apparent to one skilled in the art. The amine-aldehyde materials function as a crosslinking agent in the compositions of the invention by reacting with the hydroxy functionality of the hydroxy-containing urethane modified polyester (A) and by reaction with the hydroxy functionality on the linear polyurethane, if such materials are included in the compo~itions. The amine-aldehyde crosslinking agent i8 generally included in the coating composition in an amount of between about 5 and about 60, more preferably between about 20 and about 40 weight percent based on the weight of the hydroxy-containing urethane modified polyester present in the composition. Selection of the particular ~23~38~

amount of amine-aldehyde crosslinking agent to be employed in each composition is dependent on the desired properties o~ the coating compositions as well a~ its intended u~e as would be apparent to one skilled in the art. q~he amounts of crosslinking agent to be employed in the basecoat compo~ition and in the clearcoat composition are selected individually, i.e., the weight percent amounts of crosslinker employed in the basecoat compo~ition and in the clearcoat composition of a particular basecoat/clearcoat system may be different or be similar.
Particular preferred croRslinking agent~ are the amino crosslinking agents sold by American Cyanamid Company, Wayne, N.J. under the trademark ~Cymel~. In particular, Cymel 301, 303,325, 1130, 1156, which are alkalated melamine aldehyde resins are useful in the compositions of this invention. The crosslinking reactions ate catalytically accelerated by acids. One such catalyst for example which may be so employed is p-toluene sulfonic acid which when employed, is generally added to the composition in about .5~ by weight ba~ed on the total weight of the amine-aldehyde crosslinker and the hydroxy-containing urethane modified polyester of the composition.
The basecoat coating composition of the invention also includes pigments, as noted above. A wide variety of pigments are available and known for use in coating c4mpositions by those ~killed in the art. The amount of pigment in the basecoat coating compositions may vary.
Selection of the optimal amount of pigment to be included in the basecoat compositions would be dependent on, e.g., desired color, hiding requirements of the coating, etc., and would be within the skill of those in the art.

1~3~ 6 Addltional materials which may be employed in the coating compositions of this invention include a high molecular weight linear polyurethane which has a number average molecular weight of between about 15,000 and about 40,000, preferably between about 20,000 and about 30,000.
It may be made by reacting one of the above mentioned diisocyanates ~ and diols, 9UC h as oligoe~ter diol, polycaprolactone diol, polyoxypropylene diol, polyether dlols, etc. Suitable hlgh molecular weight linear polyurethane materials are commercially available, for examplet as Spenlite L06-30S, tavailable from and a trademark of Spencer-Kellogg, Buffalo, New York). ffl e high molecular weight linear polyurethane may be employed in the compositions in amounts up to about 60 weight percent based on the total weight of the hydroxy-containing urethane modified polyestcr ~nd crosslinking agent. When employed, it is preferred that they be included in the composition in amounts of between about 10~-60~, more preferably in amounta of about 30~-50 by weight a8 described. It has been found that by including these linear polyurethanes in the basecoat of these basecoat/clearcoat systems, the depth of color and metallic glamour of the system is improved. While thls linear polyurethane, when employed, is generally preferably only included in the basecoat composition, lt may be employed in either or both coats and the amoun~s employed are independently selected.
In addition to the above discussed components, other materials may be included in the coating compositions of this invention. These include materials such as catalysts, antioxldants, U.V. absorber~, solvents, surface modifiers and whitening agents. Solvents used in - 14 - ~ 2 ~ 8 8 2 6 the coating compoqition of this invention are tho~e whlch are commonly used, e.g., t~ facilitate spray application at high solids content and include toluene, xylene, methylethyl ketone, acetone, 2-ethoxy-1-ethanol, diacetone s alcohol, tetrahydrofuran, ethyl acetate, dimethylsuccinate, dimethylglutarate, dimethyladipate or mixtures thereof. ~he solvent in which the hydroxy-cont~ining urethane modified polyester 1~ prepared may be employed as a solvent for the compo~ition thus eliminating the need for drying the resin after preparation, if such is desired.
~ ypical of the ultr3violet light -~tabilizers that are useful in this invention are benzophenones such as dodecyl oxibenzophenone, 2,4-d~hydroxybenzophenone, hydroxybenzophenone~ containing sulfonic groups, 2-4-dihydroxy-3'5'-ditertiarybutylbenzophenone, 2,2',4'-trihydroxybenzophenone esters of dicarboxylic acids, 2-hydroxy-4-acryloxyethoxybenzophenone, aliphatic monoesters of 2,2',4-trihydroxy-4'-alkoxybenzophenone; 2-hydroxy-4-methoxy-2-carboxybenzophenone; triazoles such as 2-phenyl-

4-(2'4'-dihydroxybenzoyl)triazoles substituted benzotri-azoles such as hydroxy-phenyltriazoles such as 2-(2'hy-droxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxyphenyl) benzotriazole, 2-(2'-hydroxy-5'-octylphenyl) naphthiotria-zole.
Another type of ultraviolet light stabilizer andone that is particularly preferred for use in the coatings of this invention is that taught in U.S. Patent No. 4,480,084 entitled "Polymeric Light Stabilizers" to Kordomenos et al. These stabilizers contain the sterically hindered polyalkylpiperidine radical and at least two primary hydroxyl groups available for crosslinking with the amine-aldehyde component of the coating composition.
Typical of the antioxidants which may be em-ployed in the coating composition are tetrakis alkylene(di-alkyl hydroxy aryl) alkyl ester alkanes such as tetra-kis methylene 3-(3',5'-dibutyl-4'-hydroxyphenyl) proprion--- l 5ate methane, reaction product of p-amino diphenylamine and glycidyl methacrylate reaction product of n-hexyl-N'-phen-yl-p-phenylene diamine and glycidyl methacrylate, pentaery-thritol tetrakis (thioglycolate), trimethylol propane tris

5 (thioglycolate), trimethylol ethane tris(thioglycolate), N-(4-anilinophenyl) acrylamide, N-(4-anilinophenyl) mal-eamic acid, N-(4-anilinophenyl) maleimide, alkylhydroxy-phenyl groups bonded through carboalkoxy linkages to nitrogen atom of a heterocylic nucleus containing an imidodicarbonyl group or an inidodithiocarbonyl group 3,3-ditertbutyl-4-hydroxy cinnamonitrile, ethyl 3,5-ditert-hexyl-4-hydroxycinnamate, substituted benzyl esters of beta-substituted hydroxyphenyl) propionic acids, bis-(hy-droxyphenylalkylene) alkyl isocyanurate compounds, tetra-kis hydroxy benzyl phosphonium halides alone or in combina-tion with a dialkylthiodialkanoate, thiodimethylidyne tetrakisphenols alone or in combination with a dialkyl thiodialkanoate or phosphite or phosphonate, dihydrocar-byl-hydroxy phenyl aryl or alkyl phosphonites or phosphon-ates or phosphates or phosphites or phosphinates or phos-phinites or phosphorothionates or phosphinothionates diphenyl bis(3,5-ditertbutyl-4-hydroxyphenoxy) silane, hydrocarbylhydroxyphenyl-dihydrocarbyldithiocarbamates such as 3,5-ditertbutyl-4-hydroxyphenyl dimethyldithio carbamate and amino benzyl thioether.
In one preferred embodiment of basecoat/clearcoat compositions, the basecoat would preferably contain only a benzotriazole U,V. stabilizer such as Tinuvin 32~ (a trademark of and commercially available from Ciba Geigy, Ardsley, N.Y.) and the clea~coat would contain a lZ3~1326 benzotriazole U.V. stabilizer, e.g., Tinu~in 328, the polymeric hindered amine light stabilizer of the aforementioned concurrently filed application to Kordomeno~
et al, and an antioxidant, e.g., Irganox-1010 ~available f~om and a trademark of Ciba-Gelgy). While preferred combination~ of stabilizers and antioxidants have been described, these teachings are not meant to be limiting.
Selection of the optimal type of stabilizer and antioxidant which may be employed would be within the skill of one in the art.
Surface modifiers or wetting agents are common additives ~or liquid paint compositions. Exact mode of operation of these ~urface modifiers is not known but it i8 thought that their ptesence contributes to better adheslon of coating compositions to the surface being coated and helps formation of thin coatings, particularly on metal surfaces. The choice of surface modifiers or wetting agents is dependent upon the type of ~urface to be coated.
Selectlon of appropriate surface modifiecs will be well within the skill of the artesian. Typical of theqe surface modifierg are polybutyl acrylate and a wide variety of sllicon wetting agents which are commercially available.
For many applications of the coating composition~
of the invention, particularly high solids compositions, it may be desirable to employ flow control additives to provide sag free coatings. Among numerous such materials are NAD's such a~ described by Porter (S. Porter, Jr., and B.N. McBanè, U.S. Patent 4,025,474, May 24, 1977). These particle dispersions may be included generally in an amount up to 15~ by weight of the total composition. Other types o~ NAD's such as described by D.L. Maker and S.C. Peng (U.S. Patent 3,814,721, June 4, 1974) also may be included in the Co a ting compositions.

~2388~6 The coating composition can be applied by conventional methods known to those in the art. These method~ include roll coating, spray coating, dipping or brushing and of course the particular application S technique chosen with the particular substrate to be coating and the environment in which coating operation takes place.
Particular preferred techniques for applying these coating compositions, particularly when applying the ~ame to automobiles, is spray coating through the nozzle of the spray gun.
It will be apparent from the foregoing that th~s inventlon has industrial applicablllty to automotive applications and provldes a flexible durable coating for metal and plastic substrates.
The invention will be further understood by referring to the following detailed examples. It should be under stood that the specific examples are presented by way of illustration and not by way of limitation. Unless otherwise specified, all references to ~parts~ is intended to mean pact~ by weight.

Example I

In a suitable reactor 720 gms of Esterdiol-204 ~trademark of Union Carbide), 216 gms of trimethylol propane, 2 9~8 Oe dibutyl tin oxide and 504 gms of adipic acid were charged. The temperature was raised up to 149C
and kept at this temperature until the acid number dropped to 10. At this point 150 gms of xylene were added and the temperature was raised to 177C and kept there until the ~38~32 acid number was 2. The batch was then cooled down to 93C
and 255 gms of Desmodur W (diisocyanate, trademark, Mobay Chemical Co., Pittsburgh, PaO) were added in a period of one hour. After the end of the addition, the mixture was kept at 93C until there was no NCD group observed in an infrared spectrum. The batch then thinned to 70% NV with methyl amyl ketone and had a viscosity of Z
Example_II

In a suitable reactor 1020 gms of Esterdiol-204 10 (trademark, Union Carbide), 224 gms of trimethylol propane and 724 of DMCD (dimethyl 1,4-cyclohexanedicarboxylate available from Eastman Chemical Product~ Inc.) were charged. The mixture was heated to 193C and kept at thls temperature until 210 gms of methanol were ~tripped out.
At thi~ point, the mixture was cooled down to 149~C and 165 gms of isophthalic acid and 1.5 gms of dibutyl tin oxide were added. The temperature wa4 raised to 232C and water wa~ steipped out until the acid number dropped to 10.1.
The reaction mixture was cooled down to 149C and 4B0 parts f xylene were added. When the batch temperature dropped to 93C, 320 gms of isophoroic diisocyanate were added in a period of one hour. After the end of the addition, the mixture was kept at 93C until there was no NCO group was observed in an infrared spectrum. The batch was then thinned to tl.3% NV with methyl amyl ketone and had a visco~ity of X+.

Example III

In a suitable reactot 562 gms of Esterdiol-204 ~trademark of Union Carbide) and 360 gms of xylene were charged. The mixture was brought to reflux (149C) and 123~826 any water present was stripped out. The temperature waa loweced to 93C and 360 gms of Desmodur w ( trademark of Mobay Chemical Co.) wa~ added dropwise in a period of one hour. After the end of the addition, the mixture waq postreacted at 93C until no NCO group was obsecved in an IR spectrum. At this point, 240 gms of PCP-0301 (polycaprolactone triol, trademark of Union Carbide, New York, N.Y.) 263 gms of adipic acid, 3 gmq of dibutyl tin oxide, and 215 gm~ of xylene were added. The mixture wa~
heat~d up to 204C and water was di~tilled off until the acid number dropped below 10~ The batch wa~ then thinned with 480 part~ of methyl amyl ketone. The final prod~ct had 23 viscosity at 70.8~ NV and acid number 1.2.

Example III' In a suitable reactor 562 gms of Esterdiol-204 Itrademark of Union Carbide) and 360 gm~ of xylene were charged. The mixture was brought to reflux ~149) and any water present was stripped out. The temperature was lowered to 93C and 360 gms of Desmodur W (trademark of Mobay Chemical Co.) was added dropwise in a period of one hour. After the end of the addition, the mixture was postreacted at 93C until no NC0 group was observed in an IR spectrum. At this point, 240 gms of PCP-0301 (polycaprolactone triol, trademark of Union Carbide, New 25 York, N.Y.) 131 gms of adipic acid and 133 gms of phthalic anhydride, 3 gms of dibutyl tin oxide, and 215 gm~ of xylene were added. The mixture was heated up to 204C and water was distilled off until the acid number dropped below 10. The batch was then thinned with 480 parts of methyl amyl ketone. The final product had Zs visco~ity at 70.1 NV and acid number 3.

'J

8~3~6 Example IV

In a suitable reactor 314 gms of Esterdiol-204 (trademark of Union Carbide) and 175 gms of xylene were charged. The mix~ure wa~ brought to reflux ~149~C) and any water present was stripped out. The temperature was lowered to 93C and 202 gms of Desmodur -w (trade~ark, Mobay Chemical Co.3 were added dropw1se in a perlod of one hour. After the end of the addition, the mixture wa~
postreacted at 93C until no NCO group was observed in an IR spectrum. At this point, 359 gms of Esterdiol-204 (trademark, Union Carbide), 441 parta of PCP-0301 (polycaprolactone triol, trademark, Union Carbide), 482 gm~
Oe adipic acid, 250 gms of xylene, and 3 gms of dlbutyl tin oxide were charged. The mixture wa~ heated up to 204C and lS water was distilled off until the acid number dropped below 10. The batch was then thinned with 478 gms of methyl amyl - ketone. The final product had a viscosity of X~ at 70.1 NV and 0.9 acid number.

Example V

In a suitable reactor 562 gms of Esterdiol-204 (trademark of Union Carbide) and 360 gms of xylene were charged. The mixture was brough~ to reflux (149C) and any water pre~ent was ~;tripped out. The temperature was lowered to 93C and 300 gms of isophorone diisocyanate was added dropwi~e in a period of one hour. After the end of the addltion, the mixture was postreacted at 93C until no NC0 group was observed in an IR spectrum. At this point, 240 gms of PCP-0~01 (polycaprolactone triol, trademark of Union Carbide) 263 gms of adipic acid, 3 gms of dibutyl tin oxide, and 215 gms of xylene were added. The mixture was 1~3~826 heated up to 204C and water and xylene was distilled off until the acid number dropped below 10. The batch was then thinned with 480 parts of methyl amyl ketone. The final product had Y vi6cosity at 72. ~ NV and acid number 7Ø

s Example VI

In a suitable reactor 286 gms of neopentyl glycol and 360 gms of xylene were charged. The temperature was raised to 93C and 360 gms of Desmodur W (trademark of Mobay Chemical Co.) was added dropwise in a period of one hour. After the end of the addition, the mixture was postreacted at 93C until no NCO group was observed in an IR spectrum. At this polnt, 240 gms of PCP-0301 (polycaprolactone triol, trademark of Union Carbide) 263 gm~ of adipic acid, 3 gms of dibutyl tin oxlde, and 215 gms of xylene were added. The mixture was heated up to 204C
and water and xylene was distilled off until the acid number dropped below 10. The batch was then ~hinned wlth 480 parts of methyl amyl ketone. The final product had Z4 viscosity at 71.~ NV and acid number 0.8.

Example VII

In a suitable reactor 281 gms of Esterdiol-204, 72B gms of PCP-0200 (polycaprolactone diol, trademark of Union Carbide) and 360 gms of xylene were charged. The mixture was brought to reflux (149C) and any water present was stripped out. The temperature was lowered at 93C and 360 gms of Cesmodur W ~trademark of Mobay Chemical Co.) was added dropwise in a period of one hour. After the end of the addition, the mixture was postreacted at 93C until no NCO group was observed in an IR spectrum. ~t this ~23~ 6 point, 108 gms of trimethylol propane, 263 gms of adipic acid, 3 gms of dibutyl tin oxide, and 200 gm~ of xylene wece added. The mixture was heated up to 204C and water and xylene wa distilled off until the acid number dropped below 10. The batch was then thinned with 400 parts of methyl amyl ketone. The final product had Zl vi~cosity at 72.74 NV and acid number 2.Q.

Example VIII

In a suitable reactor 562 gms of E~terdiol-204 (trademark of Union Carbide) and 360 gms of xylene were charged. The mixture was brought to reflux (149C) and any water present was ~tripped out. The temperature w~
lowered to 93C and 360 gms of Desmodur w ~trademark of Mobay Chemical Co.) was added dropwise in a period of one lS hour. After the end of the addition, the mixture was po~treacted at 93C until no NCO group was observed in an IR ~pectrum. At this point, 108 gms of trimethylol propane, 100 gms of dimer acid ~Empol 1016, Emery, IN~.), 3 gms of dibutyl tin oxide, and 200 gms of xylene were added.
The mixture was heated up to 204C and water and xylene was distilled off until the acid number dropped below 10. The batch was then thinned with 400 part~ of methyl amyl ketone. The final product had X+ viscosity at 69.2 NV and acid number 2.9.

Example IX
In a sultable reactor 753 gm~ o~ E~terdiol-204 (trademark of Union Carbide) and 360 gm~ of xylene were charged. The mixture was brought to reflux (149C) and any water present was stripped out. The temperature was ~23~82~

lowered to 93C and 360 gms of Desmodur W (tradema~k of Mobay Chemical Co.) was added dropwise in a period of one hour. After the end of the addition, the mixture was po~treacted at 93C until no ~CO group was observed in an IR 8pectrum. At this point, 474 gms of PCP-0301 (polycaprolactone triol, trademark of Union Carblde), 263 gms of adipic acid, 402 gms of dodeconoic acid, 4 gms of dlbutyl tln oxide, and 200 gm8 of xylene were added. The mixture was heated up to 204C and water and xylene was distilled off until the acid number d~opped below 10. The batch was then thinned with 4~0 parts of methyl amyl ketone. The final product had Zl~ viscosity at 70.0~ NV
and acid number 5.2.

Example X

In a suitable reactor 136 gms of propylene glycol, 172 gms of adipic acid and 66.4 gms of toluene were added.
The mixture was heated up to reflux and 42.6 gms of water were stripped. At this point 321 gms of oligoester ~made according to Example I of U.S. Patent 4,322,508 to Peng et 20 al), 250 gms of toluene, 10 gms Oe dibutyl tin dilaurate were added. In a period of 3 hours, 396 parts of Desmondur W (trademark, Mobay Chemical Co.) were added. During the additlon, the temperature WaQ allowed to rise from 116C to 143C. The mixture was kept at this temperature until no NCO group were observed in an IR spectrum. The batch was thlnned with 860 gms of toluene and 1,260 gms isopropanol.
The final product had a ~ viscosity at 33.1~ NV.

" ~ ., ,. . .

123~826 Examples XI - XIII

~lexible basecoat compositions were formulated according to the following table:

~ ample XI XII XIII

5 ComPosit ~ _ _ _ Resin of Example I 50 Resin of Example II 50 50 Resin of Example X 100 Spenlite L06-30S1 100 100 10 cymel 11302 46 46 46 Tinuvin-32~ 3.6 3.6 3.6 PTSA (40~) 1.5 1.5 1.5 sooo-AR3 50 50 50 Xylene 75 75 75 15 I~opropyl AlcohOl75 75 75 Surfynol-1044 6 6 6 Methyl amyl ketone The above basecoats were reduced to 20 sec. at #4 Fotd Cup with methyl amyl ketone before spraying.

lTrademark, Spencer-Kellogg, Buffalo, N.Y.
2Trademark, American Cyanamid Co., Wayne, N.J.
3Aluminum Paste, purchased Silberline, Lansford, PA.
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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A flexible basecoat/clearcoat coating compostion, useful as automotive finish coats on metal and plastic substrates, which is characterized in that:

I the clearcoat composition comprises:

(A) hydroxy-containing urethane modified polyester (i) having a number average molecular weight (?n) of between about 1000 and about 10,000, (ii) having a hydroxyl number of between about 30 and about 200, and (iii) containing between about 1 and about 10 urethane groups per molecule, and being made from reactants comprising:

(1) urethane modified diol made by reacting:
(a) diol; and (b) diisocyanate , wherein said diol and said diisocyanate are reacted in a molar ration of from about 4:1 to about 4:3;
(2) polyol comprising at least about 5 weight percent triol; and (3) acid component selected from dicarboxylic acids and anhydrides thereof;

(B) amine-aldehyde crosslinking agent; and II the basecoat composition comprises:

(A) hydroxy-containing urethane modified polyester (i) having a number average molecular weight (?n) of between about 100 and about 10,000, (ii) having a hydroxyl number of between about 50 and about 250, and (iii) containing between about 1 and about 7 urethane groups per molecule, and being made from reactants comprising:

(1) hydroxy functional polyester prepared from a mixture of (a) polyhydroxy materials comprising diols and triols and (b) acid component selected from dicarboxylic acids and anhydrides thereof;
and (2) diisocyanate;
wherein in forming the hydroxy functional polyester, the proportion of reactants (a) and (b) are selected so that the OH/COOH ratio is from 6:2 to 6:5;
and wherein in forming the modified polyester the proportion of hydroxy functional polyester (1) and the diisocyanate (2) are selected so as to provide from 4:1 to 10:1 hydroxyl/isocyanate groups; and (B) amine-aldehyde crosslinking agent; and (C) pigment; and wherein either or both of said basecoat composition and said clearcoat composition individually comprises 0-60 weight percent, based on the total weight of (A) and (B) of each said composition, of a linear polyurethane having a number average molecular weight of between about 15,000 and about 40,000.

2. A flexible basecoat/clearcoat coating composition according to claim 1, wherein said hydroxy-containing urethane modified polyester of said clearcoat composition has a number average molecular weight (?n) of between about 2000 and about 4000.

3. A flexible basecoat/clearcoat coating composition according to claim 1, wherein said hydroxy-containing urethane modified polyester of said clearcoat composition has a hydroxyl number of between about 50 and about 120.

4. A flexible basecoat/clearcoat coating composition according to claim 1, wherein, in forming said urethane modified diol of said clearcoat composition, said diol (a) and said diisocyanate (b) are reacted in a molar ratio of from about 2:0.8 to about 2:1.2.

5. A flexible basecoat/clearcoat coating composition according to claim 1, wherein said polyol of said clear-coat composition further comprises diol.

6. A flexible basecoat/clearcoat coating composition according to claim 5, wherein said polyol of said clear-coat comprises about 10-80 weight percent triol and about 90-20 weight percent diol.

7. A flexible basecoat/clearcoat coating composition according to claim 1, wherein said dicarboxylic acids of said clearcoat composition comprise C6 - C12 aliphatic dicarboxylic acids.

8. A flexible basecoat/clearcoat coating composition according to claim 1, wherein said amine-aldehyde cross-linking agent of said clearcoat composition is employed in an amount of from about 5 to about 60 weight percent based on the weight of said hydroxy-containing modified poly-ester present in said clearcoat composition.

9. A flexible basecoat/clearcoat composition according to claim 1, wherein said hydroxy-containing urethane modified polyester of said basecoat composition has a number average molecular weight (?n) of between about 2000 and about 4000.

10. A flexible basecoat/clearcoat coating composition according to claim 1, wherein said hydroxy-containing urethane modified polyester of said basecoat composition has a hydroxyl number of between about 50 and about 250.

11. A flexible basecoat/clearcoat coating composition according to claim 1, wherein said polyhydroxy materials (a) comprise said diols and said triols in a hydroxyl equivalent ratio of from about 4:1 to about 1:4.

12. A flexible basecoat/clearcoat coating composition according to claim 10, wherein said polyhydroxy materials (a) comprise said diols and said triols in a hydroxyl equivalent ratio of from about 3:1 to about 3:2.5.

13. A flexible basecoat/clearcoat coating composition according to claim 1, wherein said poly-hydroxy materials employed in basecoat composition prepara-tion comprise diols which are linear, aliphatic diols.

14. A flexible basecoat/clearcoat coating composition according to claim 1, wherein said dicarboxylic acids employed in basecoat composition preparation are C6 - C12 aliphatic dicarboxylic acid.

15. A flexible basecoat/clearcoat coating composition according to claim 1, wherein said amine-aldehyde crosslinking agent of said basecoat composition is employed in an amount of from about 5 to about 60 weight percent based on the weight of said hydroxy-containing urethane modified polyester present in said basecoat composition.