CA1113630A - Cathodically depositable coating compositions - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Binders for cathodically depositable aqueous coating compositions comprising a basic binder system which is a blend or partial reaction product of a basic macromolecular component and an acidic macromolecular component, the ratio between acid and basic binders as expressed by amine value and acid value ranges between 97:3 and 65:35, and included in the coating compo-sition is at least one resin component modified with a compound of the general formula -OCN - R ?NH - CO - R']n wherein n is 1-3; R is an aliphatic hydrocarbon radical, or an aromatic or cycloaliphatic nucleus, preferably substituted with alkyl groups, and R' is the moiety of a saturated or unsaturated alcohol; a phenol optionally sub-stituted with alkyl radicals; a cyclic lactam; an aldoxime, a ketoxime; an acetoacetic acid ester, or a hydroxamic acid ester. The coating compositions, in addition to providing excellent cross-linking at normal curing tempera-tures and providing films with enhanced resistance to corrosion, have improved throwing power.

Description

The present invention is directed ~o improved coating composi-tions based on heat-hardenable binder systems which are water dilwtable on partial or total neutrali7ation of their basic groups with acids. These coating compositions are particularly suited for cathodic deposition in an electrodeposition coating process~
Canadian application Serial No. 297,182 filed February 17, 1978 discloses cathodically depositable water-dilutable coating compositions wherein a basic binder system is utilized which includes acid groups, the ratio between the basic and acid groups as reflected by the ratio of amine value to acid value, in mg KOH/g, ranges between 97 : 3 and 65 : 35. The acid and basic groups are either attached to the same macromolecule or to separate macromolecules in the basic binder system. The coating composi-tions optionally includes pigments, dyestuffs, extenders, solvents, paint additives, and additional crosslinkers. The advantages provided by the acid groups in the basic coating compositions include better crosslinking density of the cured film and reduced curing temperatures of the coating in relation to basic binders without acid groups.
It has now been found that the properties of the coating compositions of application Serial No. 297,182 can be further improved provided at least one of the components of the basic binder system is modiied by a partially blocked polyisocyanate. Accordingly, the present invention is specifically directed to cathodically depositable water dilutable coating compositions based on binder systems containing basic nitrogen groups and, in addition to the basic nitrogen groups, acid groups in a ratio as expressed by the ratio of .

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amine valuc to acid valu~, in mg K~ll/g, ranging between 97 : 3 and 65 : 35, and wherein ther0 is present in ~he coating composition at least one resin component which is modified with a compouncl of th~ general formula -OCN - R j NH - CO - R']
wherein:
n is 1 - 3;
R is an aliphatic hydrocarbon radical, or an aromatic or cycloaliphatic nucleus, preferably substituted with alkyl groups, and R' is the moiety of a saturated or unsaturated alcohol; a phenol optionally substituted with alkyl radicals; a cyclic lactam; an aldoxime, a ketoxime; an acetoacetic acid ester, or a hydroxamic acid ester.
The coatings can optionally include pigments, dyestuffs, extenders, solvents, paint additives, and additional cross-linking components. The coatings of the present invention have better throwing power, which means that the deposi-tion of th~ paint is greatly enhanced on areas remote or shielded from the anode with respect to the coating systems of Serial No. 297,182. Further-more, sensitivity to still clinging aqueous paint or rinse water, or impuri-ties of the deposited dry film is considerably reduced, which in turn leads to excellent cured films. Another advantage of the same coating is enhance-ment of the corrosion resistance of the coatings.
Binder systems particularly suitable for the modification according to the present invention are those which include more than one macromolecular component with at least one component carrying basic groups. Preferably, however, all of the main components will carry basic groups. At least one of the components will carry acid groups. A variety o raw materials are ": .

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l~nown which can be used lo synthesir~e ~he rnacromc)lecule,s carrying the basic groups. The Eollowing includes a deseription of various methods of synthesiz;ng the macromolecules which is exemplary and not complete:
-1~ preferred group of macromolecules wLth basic nitrogen atoms is formecl by adclition reaction oF epoxy compounds with secondary amines.
lllustrative epoxy group containing raw materials having in eommon the gen-eral formula - CE~ - CE~ ~ R, wherein R is H or alkyl are glyeidyl ethers of phenols, particularly of 4,4'-bis(hydroxyphenyl)pro-pane (Bisphenol A); glycidyl ethers oE phenol formaldehyde condensates of the Novolak type; glyeidyl esters of aliphatic, aromatic, or eyeloaliphatie mono- or polyearboxylic acids; glycidyl ethers of aIiphatic or cycloaliphatic diols or polyols; eopolymers of glycidyl~meth)acrylate, and epoxidation .
products of aliphatic or cyeloaliphatie di- or polyolefinesO A more eomplete survey of epoxy group eontaining raw materials is found in A. M. Paquin "Epoxidverbindungen und Epoxyharze, " Springer 1958. Seeondary amines suitable for addition to the epoxy group containing raw materials inelude dimethylamine, diethylamine or higher homologues or isomers thereof.
Secondary alkanol amines are particularly suited, ineluding diethanolamine9 diisopropanolamine, or higher homologues or isomers thereoe. Cyclic secondary amines sueh as ethylene imine, morpholine, ancl piperidine can also be employed. The reaction of the epoxides with primary/tertiary or secondary/secondary diamines leads to compounds with cationic character.
It is evident that the epoxy eompounds can be modified with other eompounds such as mono~ or diearboxylie aeids. It is essential that the produets earry .
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a sut`ficierlt number Or ba~sic gro~lps to cnabLe acccptable dilution with waterupon partial neutralization with acids.
- Macromolecules with basic nitrogen atoms are also obtained through copolymerization of suitable basic monomers with hydroY~yalkyl-(meth)acrylates, pre~erably in the presence Oe other copolymeriY,able com-pounds. Such basic monomers inc:lude the (meth)acrylates, such as N,:~-dimethylaminoethyl(meth)acrylate; vinyl piridine; N-vinylirnidazoL, and N-vinylcarbazol. The basic group containing monomers can be copoly-merized with other monomers including hydroxyalkyl(meth~acrylates; other (meth)acrylates, i. e., those not containing basic nitrogen groups; (meth)-acrylamides; vinyl aromatics such as styrene9 vinyltoluol, and alpha-methyl styrene .
- A further group of macromolecules with basic nitrogen atoms are the substituted oxazolines including those obtained by the cyclizing con-densation of amine alcohols, such as trishydroxymethyl aminomethane or

2 -amino-2 -hydroxymethyl-1, 3-propanediol, with aliphatic carboxylic acids or carboxy group containing macromolecules. A comprehensive survey of useful oxazolines is set forth by J. A. Frump, Chemical Review, 1971~ Vol.
71, No. 5, pp. a~83 - 505. Polyesters with the substituted o~azoline groups are disclosed in U.S. Patent No~. 3, 882,188 and in British Patent No.
1,411,568.
- A further group of macromolecules with basic nitrogen atoms is obtained by addition reaction of anhydride group containing compounds with alkanol amines, particularly with dialkylalkanolamines, e. g. 9 dimethyl-or diethylethanolamine. The addition reaction is carried out at from 50 to 150 C., preferably 90 - 120C., with semi-ester formation. Suitable ~.~Li363(:~

stL~ting materials a~e succinic anhydride derivatives or Diels~Alder ad-ducts as c:an, Eor e~ample, be obtained by addition oE maleic arlhydride to compo~u;lcls with isolated or corljugated double bonds. ~mong this group are, for example, adducts of maleic culhydricle to unsaturated oils and fatty acids, and rosin acids to diene polymers, unsaturated hyclrocarbon resins, and the like~ E~urthermore, copolymers carrying anhydride structures, such as styrene-maleic anhydride copolymers, can be employed, Nitrogen groups can also be introduced into the macromolecule by the reaction of acid anhydride groups or semiesters thereof with diamines carrying one primary and one tertiary nitrogen atom and is a particularly favorable method where one of the components includes a macromolecule into which the basic groups are introduced through condensation of dicarboxylic acid anhydrides with primary/tertiary diamines, with the formation of water.
Suitable starting materials are the succinic anhydride derivatives above noted or Diels-Alder adducts or copolymers. Oligomeric liquid polymers of dienes are particularly preferred for adduct formation, especially of 1, 3-butadiene. The quantity of added dicarboxylic anhydride usually lies between 10 to 25 percent by weight. The adduct anhydrides are as men-tioned partially reac$ed with primary/tertiary diamines with water being formed and thereby introducing tertiary basic nitrogen atoms in addition to amide and imide groups. The quantity of diamine compound is chosen in order that for one mole of anhydride group about 0. 3 - 0. 8 moles of diamine are used. A residual quantity of carbo~y groups is provided as a precaution, which subsequently is set free from the latent form of the residual anhydride groups through reaction with water or monoalcohols.
Examples of suitable diamines are dimethylaminoethylamine, diethylamino-ethylamine~ dimethylaminopropylamine, diethylaminoprop~lamine and ~363~

ilornologl:les tile]~cof. 'L'~-le diarr~ e i,s ackle(l at between 50"C, arld 1~0 C.
The reaction is finished at between 160 and 220~ C., the formation of the preferred acid imide group being traceable ~Nith the quantity of the water formed or with magnelic nuclel:ls resonance spectroscopy. At lower reac-tion temperatures the ~orrnation o:~ an a.cid a.mide group is tra.ceable only bynucleus resonance measur ement. rrhe further component of this particularly favorable method pr eferably are reaction product,s of epoxy group containing compounds, particularly of polyglycidyl ether s of polyvalent phenols, such as Bisphenol ~, or of Novolak resins with secondary amines. Suitable epoxy compounds also are polymers carrying epoxy groups, based on dienes or acrylic copolymers. In acldition to the secondary aliphatic or cycloaliphatic amines generally used, a derivative of diethylene triamine can be used, both primary amino functions of which are masked through ketoimine fo~mation with at least 2 moles of ketone, The addition of the secondary amlne or alkanolamine to the epoxy resin is carried out at a temperature between 30 to 150 C., and is generally an exothermic reaction. In case of the preferred epoxy resins melting at higher temperatures, it is advantageous to coemploy solvents inert to the epoxy groups, secondary amines, and hydroxy groups.
Such solvents include ketones, such as methylethylketone and methyliso-butylketone; esters, such as ethylaceta.te, butylacetate, and ethylglycol acetate; ethers, such as tetrahydrofurane, ethylene glycol diethyl ether, and the like. The quantity of secondary amine or alkanol amine is chosen in order that the reaction pr oduct has an amine number o~ between 35 and 120 mg KOH/g. In general this value is attained, even if not all epoxy groups are consumed~in the reacti.on with the amine compound, In this case it is of advantage to esterify the remaining hydroxy groups with satura.ted ~3630 or unsaturated carbo~ylic acids. In copenc1ing appLication Serial No.
816, 937 deposited July l~l, 1977, methods of introducing basic grc~ups into macromolecules by reacting hydroxy or carhoxy group containing com-pounds with basic monoisocyanates are described.
Various methods are known for introducing acid g~roups into the binder system. It is possible to admix a suitable quantity of a macromole~
cular compound carrying acid groups with a basic resin~ Alternatively7 a chemical combination between the basic and acid components can be effected through reaction of an acidic macromolecular compound, or an intermediate compound, with a basic resin. The acid compounds used according to this method are prepared in a separate reaction step~ A preEerred group of -- macromolecular compounds are the addition compounds obtained through reaction of ~lpha, beta-unsaturated dicarboxylic acids or anhydrides with compounds having isolated or conjugated double bonds (adducts), In case of adduct formation with anhydrides, it is necessary to open the anhydride ring with water or alcohols and to thereby set Eree th0 carboxy groups.- Starting materials for such adducts are unsaturated oil Patty acids, synthetic or natural hydroxy-free esters, mixed esters thereof with rosin acids, as well as diene polymers or hydrocarbon resins.
A still further group of macromolecular compounds with acidic character are the conventional polyesters or alkyd resins selected to carry a sufficient number of free carboxy groups. The required acidic character is achieved either by interrupting the esterieication at the desired acid value or by the formation o partial esters of di- or polycarbogSrlic acids with hydroxy-rich polyesters with low acid values. Furthermore, according to the present invent;on, copolymers can be coemployed which carry free 63~

carboxy groups. I1he ~ crerre(1 c opolymers arc those with acrylic or vinyl~lromatic structur~s> e.g., copolymers oL` acrylates, styrene., acrylic acicl, methacrylic acic1, maleic acid derivati~/es, etc.
The acid components, in adclition to the essential acid grvup.s~may contain other functional groups, suc:h as hydroxyl groups, a-mide groups, imine groups and amine groups. If these aclditional groups are of basic nature, they must be considerecl when calculating the desired ratio in the binder of the basic and acid groups.
The ratio between the basic and acid groups in the binder sS~stem is expressed as the ratio between amine number and acid number (mg KOH/g)~
The coating compositions of the invention are basecl on binders wherein such ratio is between 97: 3 and 65 :35.
The modification of at least one of the components constituting the total binder is carried out by reaction with a compound of the general formula OCN - R ~ NE~ - CO - R~
n wherein n is l - 3;
R is an aliphatic hydrocarbon radical or an aromatic or cycloaliphatic nucleus, preferably substituted with alkyl groupsJ and R' is a radical, reduced by one reactive hydrogen atom, of a saturatedor unsaturated alcohol, or a phenol, an alkyl substituted phenol, or a cyclic lactam or an aldo~ime or ketoxime or an aceto acetic acid ester or a hydroxamic acid ester.
These compounds are partially masked polyisocyanates obtained through ~3t;3S31 reaction o~ polyisocyanates, preeerabLy polyisocyanates c arrying iso-cyanate groups with di~ferent reactivity, with a blockirIg agent. 2,4-toluylene diisocyanate is preferably usecIJ one of the isocyanate groups being blocked with monoalcohols, phenols, o~imes, lactarns, ox acetic acid esters. The blocking agents may also carry polymerizable double bonds, for example the blocking agent can be a mono-hydroxyacrylate. These partially masked polyisocyanates contain an average of one free isocyanate group.
The reaction oE the partially mas~ed polyisocyanate with one of the components of the coating composition is carried out at from 60 to 160 C., optionally in the presence of a solvent inert to isocyanates~ and is carried on until the Eree isocyanate groups are substantially consumed. The highest applicable reaction temperature is governed by the nature of the masking agent.
The progress of the reaction is reflected in the decreasing isocyanate content, optionally also the decreasing acid value, the acid value becoming c/~nstant in a range of from 5 to ~6 mg KOH/g at the end of the reaction. The amine number of the reaction product is from 25 to 7Q rng KOH/g. For easier handlingJ the components subsequent to the reaction with the partially masked polyisocyanate, may be diluted with solvents. Suitable solvents are the low glycol ethers, such as ethylene glycol monoethylether, ethyleneglycolmono-isopropylether, and ethyleneglycolmonobutylether. Other suitable solvents are alcohols such as ethanol, propanol, isopropanolJ butanol, and the like.
Another possibility is the neutralization with acids and dilution with water.
Suitable acids are mainly monobasic low molecular weight organic acids such as formic acid, acetic acid, lactic acid, and the like.
It has been determined that at times it may be advantageous with regard to the corrosion resistance with respect to salt solutions o the coat-.~: , ., ' . .

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illgS to et-lhal-lce the harcle~ g ten(lency ot tlle coatin~ compositions through the introd~lction of an adclitional c rosslinking component, Suitable crosslink-ing agents are urea-melcannine or phenol-formaldehyde condensates particu~
larly of the resol type. They are prepcLred according to known methods by alkaline condensation of ornlaldehyde ancl substances splltking off formalde-hyde to urea, nmelamine7 ben~oguanarrline, acetoguanamine, phenol, cresol, p-tert. butyl phenol, Bisphenol ~, and the like. The methylol compounds rnay optionally be etherified with alcohols. Particularly preferred is the use of a phenol-formaldehyde condensate, the phenolic hydroxy groups of which are etherified with allyl alcohol, The amount of these crosslinking agents em-ployed may range between 3 ancl 20 percent of the tota:L binder. Since the crosslinking agents are in most cases not directly water soluble~ they are co-reacted with at least one of the binder components through careful conclen-sation. The extent of this reaction is carried to an excellent water solubility of the reaction mass upon neutralization with low molecular organic acids, The temperatures required in general for this purpose range Erom 60 to 120 C., and the reaction time ranges from 1 to 6 hours. Additional cross-linking agents are completely masked polyisocyanate compounds. In consti-tution they are equal to the above-described partially masked polyisocyanate compounds, with the exception that they do not carry a free isocyanate group.
The preparation of the binders of the present invention is carried out either by mi~ing the components at temperatures which safeguard excel-lent homogenization or by partial reaction between the various cornponents at temperatures of up to 200 C. g preferably up to 100 C., safeguarding satisfactory dilutability in water of the product. Mixing and reaction is con-veniently effected in water-tolerant solvents such as alcohols7 glycol ethers, ketones7 or ketone alcohols.

1~3~;310 The binder systerrl or the single cornponents may be processecl together with pigments, es~tenclers, anticorrosion pigments, ancl optionally paint additives or crosslinking catalysts to provide coacting compositions suitable for the desirecl industrial application~ Uselul color pigments include titanium dioxide, carbon black, iron oxides, and phthalo-cyanines. Anti-corrosion pigments include leacl silicate, lead oxide, lead chromate, lead silico-chromate, and strontium chromate. Normally used extenders are aluminum silicate, talcum, barium sulfate, highly dispersed diatomaGeous earth, ancl the like.
The basic nitrogen atoms of the binders of the present invention are neutralized partially or totally with organic and/or inorganic acids. The degree of neutralization depends on the individual binder system. In general that much acid is added which gives a coating composition which in its form of application at a pH-value of from 4 to 9, preferably 5 to 7~ is water dilutable or dispersable. The concentration of the binder in water lies in the range of 3 to 30 percent by weight, preferably 5 to 15 percent by weight.
On deposition the aqueous coating composition containing the binder of the invention is wired to an electrically conductive anode and an electrically conductive cathode, the surface of the cathode being coated with the coating composition. A variety of chemically conductive substrates may be coatedl in particular, metallic substrates including steel, aluminum, copper, and the like~ but also metallized plastics or other materials covered with a conductive coat. After deposition, the coating is optionally rinsed with water and cured at elevated temperature. For curing, temperatures of from 130 to 220C~, preferably 150 to 190~C., are employed. The curing time ranges from about 5 to 30 minutes, preferably 10 to 25 minutes.

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The ~olLowing c7~rnr)1es are for illustLative purposes ancl are not to be construecl as limiting the scope of tlle invention. Parts ar e by weigSht unless otherwise clesignated.
Preparation Of Partial Compouents A:

, , . _ ~ or abbreviations and quantities, see the keg to, and Table 1.
The unsaturated oil is mixed with inhibitors 6J 7 and heated to-gether with maleic anhydricle to 200 C. while stirring, ancl is reacted at this temperature until no Eree maleic anhydride can be trac:ed. Upon cooling to 150 C., inhibitor 8 ancl the amine are slowly added while reiluxing. The 10 batch is reheated to 200 C., the reaction water being clistilled of. Upon cooling to 120 C., the batch is diluted with AEGLAC (a) and the remaining anhydride structures are opened at 90 to 100 C. with the compounds listecl as 11. After further dilution with A:EGLAC (b~ catalyst 12 is added, and, at 60 to 120 C., the urethane compound (U1 - U4) is added. The reaction is 15 carried on until the listed acid value is reached.
For partial components A6 and A7, an adduct compouncl only is prepared, the anhydride groups of which are opened with water or by esteri-fication with alcohols.

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_T 1~ :B :[, E
Cornposition Ancl Speci~ication Of Partial Components A
A 1 A 2 ~ 3 , ~ 7 Linseed oil 400 - - 200 - - 500 S Polybutadiene (1 ) - 5 oo - - _ _ ~
Polybutacliene ~2) - - 380 Polybutadiene (3) - - - - 400 Polybutadiene (4) - - - - _ 400 Polypentadiene (5) - - - 200 Inhibitor (6) 0.1 0,1 0.1 0.1 0.1 Inhibitor (7) - - - - - 4 5 ~ Maleic anhydride 100 100 100 100 100 100 100 Inhibitor (8)0. 2 0. 25 0,19 0. 2 0. 2 N, N-Diethylamino-propylamine 65 - 78 65 26 N, N-Dimethylamino propylamine - 68 DIAC (9) - - - ~ - 50 AEGLAC (a) (10)62 166 140 62 134 - . _ H2O distilled (11) - - - _ 14 _ 20 Methanol (11)15 10 - 15 - 30 n-Butanol (11) - - 30 AEGI,AC (b) (10)318 183 - 318 224 Isopropanol - - - - - 170 150 Catalyst (12)0.74 0.7 0.65 0.74 0.7 Ul (13)195 - - 195 U2 . ~13) - 253 3~3~

rl1 ~ B~ 1 (cont'd) ~l ~2 ~3 ~4 A5 A6 ~7 .. ~
U3 (13) _ _ 110 - ~ ~ ~
U'L ~1 3) - - - 25 3 Solvent Eor adjustment of solids content (14) - AEGL ~EGL - - - -Amine value mg KOH/g 45 50 53 a~s 16 Acid value mg KOH/g 19.4 15 18 19.4 90 90 150 Solids content Percent by weight 60 60 55 60 60 70 80 Key to Table 1 (1) liquid butadiene homopolymer, viscosity: 900 mPa.s (~L5C.); microstructure: 90% 1,2-vinyl-double bonds;
(2) liquid butadiene homopolymer9 average mblecular weight ca.
1500, viscosity: 700 mPa. s (25 C. ); microstructure: 20%
1, 2-vinyl-, 40% lJ4-trans-~ 40% 1,4-cis-double bonds;
(3) liquid butadiene homopolymer, viscosity: 800 mPa. s (20 C. )9 iodine number: 50; microstructure: 70% 1~4-cis-, 28% 1"4-trans-double bonds~

(4) liquid butadine homopolymer, average molecular weight ca.
1400, microstructure: 75% 1, 4-cis-, 25% 19 4-trans-double bonds;
(5 ) liquid poly- 1, 3 -pentadiene, average molecular weight ca.
1000; ~iscosity: 30, 000 mPa. s (30~ C. ) (6) N" N'-diphenyl-p-phenylenediamine (7) Cu-naphthenate (9% metal content) (8) 29 6-di-tert. butyl-4-methylphenol (9) diacetonealcohol (10) ethyleneglycolmonoethyletheracetate (11) reactants for opening the anhydride structures -(12) stanrlous dibutyLdilaurate (13) urethane compouncl Ul: 17~ g tolylenediisocyanate are reacted at 60 C. with 60 g isopropanol in 156 g AECI.AC until an NCO~value of 18 is reached.

U2: In the presence of 0. 3 g of catalyst (12) and 203 g of water-free AEGLAC, 174 g of tolylenediisocyanate are reactecl at 120 C. with 130 g of ethylacetoacetate until an NCO-value of 16 is reached.
U3 : 174 g of tolylenecliisocyanate are reactecl with 113 g ~.
-caprolactame at 60 C. ~ in l91 g of AEGLAC, until an NCO-value oE 15 is reached.

U4: 174 g oL tolylenediisocyanate are reacted with 130 g of 2-eth~lhexanol in 203 g of A:EGLAC at 60 C., until an NCO-value of 14 is reached.
(14) AEGL: ethyleneglycol monoethylether Determination Of The NCO-Value:
About 2 g of the sample are accurately weighed into a dry Erlen-meyer flask and dissolved in toluol with gentle heating. Exactly 10 ml of 20 reaction solution (prepared through dissolution of 0. 5 moles of diisobutylamine in 940 ml of toluol) is added with a pipette. After 3 minutes of reaction time - at room temperature a few drops of bromophenolblue indicator (methanol solution) are added and the sample is titrated with 0. 5 n alcoholic EI Cl until the color turns yellow. A blank test is made the same way.
B = consumption 0. 5 n E~ Cl for blank test V = consumption 0. 5 n H Cl of sample A = theoretical consumption of 0. 5 n H Cl for neutralization of the basicity of the resin E = weigh-out in g NCO - value = B - V ~ A
.
E

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Partial Com~ollcrlt r~l:
950 g oE a commercially available bisphenolglycidyl ether with an epo~y equivalent weight o~ 950 - 1000 are heated with 192 g ethylglycol ace-tate to 100C., while stirring ancl hel(i, until ahornogeneous solution is formed. Then 98 g taLl oil fatty acids and 1 g Or triethyl amine are added and the batch is heated to 130 C., until the acid value is below 1 mg KOH/g. ~t 100 C., 44 g of diethylamine are slowly added while refluxing. The batch is reheated to 130 C. and stirred for another hour at this temperature. The viscosity of a solution oE 55 g of reaction mass and 45 g of ethylglycol is N, Gardner. The batch is diluted with 45 g of ethyl glycol. At 80a C. 186 g of a bisphenol-resin, 65%, is added which is prepared through alkaline condensa--- tion of 1 mole bisphenol and 4 moles of formaldehyde. Ater 5 hours oE reac-tion time at 80 C. J the batch is cliluted with ethyl glycol to a total solids content of 70 percent. The amine value of the non-volatile portion is 28 mg KOH/g, the viscosity of a solution oE 10 parts by weight of reaction product and 5 parts by weight of ethyl glycol is K, Gardner.
Partial Component B2:
475 g of an available bisphenol glycidylether with an epoxy equiva-lent weight of 450 - 500 are dissolved homogeneously in 96 g of ethylglycol acetate at 100 C., while stirring. Then 22 g of acrylic acidJ 0.022 g of hydroquinone and 1 g oE triethylamine are added and reacted at 130 C., until an acid value of 1 mg KOH/g is reached. At 100 C. 52 g of diethanol amine are added and the batch is held at 130C. for 1 hour. The batch is diluted with ethylglycolacetate to a solids content of 78 percent and is reacted at 80 C.
for 5 hours with 61 g Or methylolphenolallyl ether (viscosity 30 Poise at 25C,). The batch is further diluted to 60 percent solids with ethyl glycol - 18 ;-~1.13~i3~11 acetatc arlc~ aL ~;0~C. 2L7 g Or tl,( ureth.ln~ corrlpound dcscribed be]ow are added~ together with 0. 7'L g of stanllous dibutylclilaurate. The reaction is carried out at $0 C. until an NCO-value of zero is attainecl. The reaction product llas a solicls content of 60 percent and the arnine value is 3~?i mg KOH/g (DIN 53 176) Eor the non-voLatile portion. The urethane compound used in this reaction was prepared lrom 174 g of tolylene diisocyallate (isomer blend) and 87 g methylethylketo~ime and 174 g of ethylglycolacetate, the oxime being aclded at 30'' C. and the reaction being finali%ed at 60 C., until an NCO-value c~f 17 is attained.
Partial Component Bi~
103 g of diethylene triamine ancl 220 g of methylisobutylketone are heated to boiling temperature in a reaction flask equipped with reflux conclen-sor and water separator, until about 36 ml of water have separated. After distillation of the surplus ketone~ about 270 g of the diketimine of diethylene triamine are obtained.
In another reaction vessel equipped with stirrer and thermometer, 475 g of bisphenolglycidyl ether having an epo~y equivalent weight of 450 -500 are dissolved homogeneously at 100 C. in 126 g of ethylglycol acetate.
Then 140 g of dehydrated castor oil fatty acid and 1 g triethyl amine are added and reacted at 120 C., until the acid value has fallen below 1 mg ~OH/g. At 90C~, 123 g of the above-noted ketimine are added and the batch is heated to 130C. A sample of the reaction mass~ with alittle butylglycol and acetic acid, is clearly soluble in water. The viscosity of a solution OI
a, g of reaction mass and 6 g ethylglycol is L, Gardner. The batch is cooled to 90 C. and 32 g water and 100 g of ethylglycol are added. A resin solution with 70 percent solids content is obtained. The amine value of the non-~13~3 vol~ltil~ f)ox L~ i.c, clt~"~ n ~ r~o~
Partial Cornpon~nt B~:
500 g of linseecl oil is reacted with 100 g maleic anhyclride at 200" C. in the p r escnce oF 5 g o~ a copper napllthenate solution with 9 per cent Cu, until tlle content of free maleic anhyc~ric3e ~lag fallen l~elow 1 percent.
The viscosity of a solution of 80 g of adduct and 40 g of ethylene glycol mono-ethyl ether acetate is about 50 seconcls (DIN 53 211) and the acid value is 170 mg KOH/g. At 150C., 130 g of diethylaminopropylamine are added within one hour and the batch is held at 180C., until the total quantity of 10 amine has reacted. After cooling to 120 C., the solids content is ad justed to 80 percent with 175 g of ethylene glycolmonoethyl ether. (Amine number:
80 mg KOH/g) Examples 1 - 7:
The partial components are blended as listed in Table 20 The 15-quantities refer to resin solids.

R ati o Partial Components Amine ValueAcid Value Example 1 50 Al 50 Bl 79 21 Example 2 60 A2 40 B3 89 11 Example 3 40 A3 60 B2 85 15 Example 4 30 A4 70 B3 92 8 Example 5 20 A5 80 B4 79 21 Comparison Example 6 20 A6 80 B4 78 22 Example 7 10 A 7 90 B2 70 30 ~3~:i30 E~;a m ple 8:
~t reflux tempe.rcl.ture, 238 g of clim~thylaminomethylrnethacrylate, 24 g of acrylic acid, ~L10 g oE 2-ethyl-llexylac:rylate, 340 g of styrene are copolymerize-l in 1000 g of ethylglycol acetate in the presence of 20 g of doclecylmerkaptan and 20 g Or azodiisobutyronitrile, ùntil the solids content has reached 48. 4 percent. The amine value of the copolymer, on resin solids, is about 8~ mg ~OH/gJ the a.cid value about 18 mg KO:EI/g.
At 80 C., 124 g of the urethane compound descrlbed below are added and the charge held at 80 C. I;mtil the NCO-value has a.tta.ined æero andthe resin solution has become wa.ter dilutable upon neutralization with acids.
The solids content of the resin solution is 51 percent, the amine value of the resir~ solids is about 75 mg KOH/g, the acid va.lue about 8 mg KOH/g ~base -acid ratio 90: 10 mg KOH/g).
The urethane compound used in this reaction was prepared from 222 g isophorone diisocyanate and 130 g beta-hydroxyethylmethacrylate, in the presence of 1. 3 g of hydroquinone, by reaction at 80 C. until the NCO-value was 12.
Evaluation Of The Binders Each 100 g of the listed binders based on resin solids were mixed with the required quantity of acid and, while stirring, made up to 1000 g with deionized water. From a. 10 percent solution, steel panels wired at the cathode of an electrodeposition system were coated electrophoretically.
. The deposition time was 60 seconds in all cases. The coated substrates were rinsed with deionized water and cured at elevated temperature. The average film thick~ess of the cured films was from 13 to 17l1m . Table 2 gives the compiled results.

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l~ey to l'c-hle 3 ~ _ . . , 1) Quantity Or acid in g :fo:r 10() g resi.rl solids 2) E is acetic acid (80%, aqueous) 1~ is lactic acid (80%, aqueous) A is formic acid (80%~ nqueous) 3) measured on a lO~o a.queous solution ~) Konig pendulum hardness, l~I:N 53 157 (seconds)

5) Erichsen indentation DIN 53 156 (mm)

6) hours of water soak at 40 ~'. until blistering and co:rrosion become visible

7) ASTM-B-117-64 salt spray: 2 mrn of corrosion at the cross incision after the recorded hours l:~or this test degreased non-pretreated steel panels were coated with a pigmented paint containing 100 parts by weight of resin solids, 20 parts by weight of aluminum silicate pigment, and 2 parts by weight of carbon bla.ck.

8) Determination of Throwing Power:
A plastic cylinder of 400 mm height and 60 mm diameter is filled with 1 liter of paint. At a distance of about 1 mm from the bottom of the cylinder a steel disc having a diameter of 53 mm is mounted as an anode. The cathode is a squa.re hollow bar with dimensions as follows: . 300 mm length a.nd lO mm of clear width, having fixed inside in diagonal posltion a steel strip of 300 x 14 x 3 mm. The cathode is imme.rsed into the paint to a length of 270 mrn. Painttemperature is 25Co During deposition it should not rise by more than 1 or 2 C~ Deposition is carried out with constant voltage during 3 minutes. The deposition voltage is chosen in order that substa.ntially no over-deposition is efi:ected at the - : , . .

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outsicle oI` t~lC cath(-cl~ scluare. l~fter (iepositiorl the steel strip is removecI ~rom the cathode and rinsed with tap water. The film is curecl in an air circulation oven for 30 minutes at 180 C. The visible length of deposition on the strip i,s recorcled.

Various modifications can l)e made in the aEoresaid examples and still fall within the scope of the present invention. tt is only e~ssential that at least one resin component oE the binder system be reactecl with the select monoisocyanate through a reactive group on the resin component in an arnount sufficient to improve the throwing power ~md/or corrosion resistance of a 10 coating composition containing the bincler. The actual amount basetl on the illustrative examples will be selected depending upon the rnaterials employecl and the end application of the coating system.

, . ' , ' :' - -, ' ~ ' ~ ` . . :

Claims (16)

IT IS CLAIMED:

1. Cathodically depositable water dilutable coating compositions comprising a binder system including at least one macromolecular compo-nent, the macromolecular component or components of the binder system containing basic nitrogen groups and acid groups, the ratio of basic groups to acid groups as expressed by the ratio of amine value to acid value, in mg KOH/g, being between 97 :3 and 65: 35, and a macromolecular component of said binder system being reacted with a monoisocyanate compound having the formula -OCN - R ? NH - CO - R'] n wherein:
n is 1 - 3;
R is an aliphatic hydrocarbon radical, or an aromatic or cycloaliphatic nucleus, and R' is the moiety of a saturated or unsaturated alcohol; a phenol optionally substituted with alkyl radicals; a cyclic lactam; an aldoxime, a ketoxime; an acetoacetic acid ester, or a hydroxamic acid ester.

2. The coating composition of claim 1 wherein the binder system includes in admixture at least two macromolecular components with one of said macromolecular components containing basic nitrogen groups and a second macromolecular component containing acid groups.

3. The coating composition of claim 1 wherein the binder system includes a macromolecular component containing both acid and basic groups.

4. The coating composition of claim 1 wherein the binder system includes a reaction product of a basic macromolecular component and an acid macromolecular component.

5. The coating composition of claim 2 wherein the macromolecular component with acid groups contains reactive functional groups in addition to the acid groups.

6. The coating composition of claim 5 wherein said additional functional groups are hydroxyl or amine groups.

7. The coating composition of claim 3 wherein said macromolecular component contains the basic and acid groups in one resin molecule in the stated ratio and is further reacted with said monoisocyanate component.

8. The coating composition of claim 1 wherein said macromolecular component with basic nitrogen groups is the reaction product of an epoxy compound and a secondary amine.

9. The coating composition of claim 1 wherein the macromolecular component containing basic nitrogen atoms is the copolymer of a basic mono-mer containing ethylenically unsaturated units and a hydroxyalkyl(meth)-acrylate.

10. The coating composition of claim 9 wherein the basic monomer is a member of the group consisting of N,N-dimethylaminoethyl(meth)-acrylate; vinyl piridine; N-vinylimidazol, and N-vinylcarbazol.

11. The coating composition of claim 10 wherein the copolymer includes a member of the group consisting of (meth)acrylamide, styrene, vinyltoluol, and alpha-methyl styrene.

12. The coating composition of claim 1 wherein the macromolecular component is the reaction product of an anhydride group containing compound with an alkanolamine.

13. The coating composition of claim 1 wherein the acid groups are on a macromolecular component which is the reaction product of an alpha,beta-unsaturated dicarboxylic acid or anhydride with a compound having isolated or conjugated double bonds.

14. The coating composition of claim 1 wherein the acid groups are on a macromolecular polyester.

15. The coating composition of claim 1 including additional cross-linking agents.

16. The coating composition of claim 15 wherein the additional crosslinking agent is a formaldehyde condensate of a resol-type phenol.