CA2038786A1 - Process for the preparation of cationic binders for coatings and their use - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Binders for cathodic electrodeposition coatings based on epoxy resin-amine adducts are obtained by incor-poration of oxazolidone structures in combination with diamine bridges built up in a specific manner. The modi-fied epoxy resin-amine adducts are used in electro-dipping coatings together with crosslinking components. The stoved coating films have excellent corrosion protection, espe-cially at the edges of workpieces.

Description

2502/US-3480/fdl 2~3~3786 PROCESS FOR THE PREPARATION OF CATIONIC ~INDERS
FOR COATING5, THE BINDERS PRODUCED, AND THEIR USE
., This invention relates to a process for the prep-aration of cationic binders for coatings based on modified epoxy resin-amine adducts; to the binders prepared by such process, and use of the binders in combination with cross-linking components in cathodic electrodeposition coatings.

BACKGROUND OF INVENTION
Stringent requirements are imposed on binders for electrodeposition coatings. Not only is it necessary to prepare the electrodeposition bath and the ultimate electro-deposited coating without difficulty, but a very high pro-file of properties is also required in the binder such as throwing power during the electrodeposition and surface characteristics of the films produced, including corrosion resistance and stone-chip resistance in connection with good adhesion to the substrate being coated and to subsequent coats of paint. To achieve favorable dilution properties o~
the coating~ in an electro-dipping plant, the binders should have a low viscosity. on the other hand, a high molecular weight is one of the preconditions for achieving good resis-tance properties in the final crosslinked ~ilms, which is usually associated with a high viscosity of the binder~

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Similar contradictory requirements exist in respect to the development of a high electrical film resistance during deposition in order to achieve a good throwing power, and the simultaneous desire for a high ~ilm thickness with ex-cellent surface quality.
A compromise between an optimum in deposition characteristics and the propertiPs of the crosslinked coat-ing films is obtained in di~ferent ways by di~ferent types of modification of bisphenol A-epoxy resin-amine adducts or phenol novolak-epoxy resin-amine adducts as disclosed in the literature. Thus, EP-A2-0,355,654, corresponding to U.S. Patent No. 4,992,516, describes a high molecular weight structural unit which contains oxirane functional groups and has a low glass transition temperature, with a polvhydroxy-diamine as a modifier, which enables the properties such as solubility properties, throwing power, layer build-up, and film flow to be optimized. It is also known that prod-ucts carrying urethane or urea groups such as described in EP-A2-0,218,812, corresponding to U.S. Patent No. 4,845,171, or in EP-B1-0,209,857, corresponding to U.S. Patent No.
4,711,934, produce particularly good results in respect to their corrosion protective properties. The incorporation of these urethane or urea groups in general has the e~fect o~
increasing the glass transition temperatures of the blnders.
However, the consequence of this is a deterioration in the :

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' film flow and a reduction in the maximum layer thicknesses which can be achieved . To achieve high film layers and excellent surface qualities, modifications must be made to such binder systems to render the polymer structure flex-ible, which in most cases again causes a reduction in the : resistance properties of the stoved films, especially at the edge~ of the workpieces, and a reduction in the adhesion of subsequent coats. The positive properties of these binders, that is to say their excellent corrosion resistance and : stone-chip resistance in connection with the good adhesion to subsequent coats, can therefore only be partly utilized.
Many methods for plasticizing primers which can be deposited cathodically are known from the literature as disclosed, for example, in Austrian Patent No. 381,115, corresponding to U.S. Patent No. ~,659,800; U.S. Patent No.
4,104,147, and EP-A2-074,634, corresponding to U.S. Patent No. 4,419,467. However, such modifications, providing an increasing degree of plasticizing, result in further disad-vantages such as a decrease in tha wet film resistance and a deterioration in the throwing power of tKe coating.
: SUMMARY OF INVENTION
It has now been found that binders based on epoxy resin-amine adducts can be modified to enhance the binder characteristics by incorporation of oxazolidone structures in combination with diamine bridges built up in a specific .

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'',.'! manner. Thus, the formation o~ oxazolidone structures dur~
ing reaction of isocyanates with epoxide compounds is known from M. E. Dyer and D. swern, Chem. Rev. 67, 197 (1967); or J. E. Herweh and W. J. Kaufmann, Tetrahedron Letters No. 12, pages 809-812, Pergamon Press, GB (1971), and takes place in accordance with the equation -H H
R-NCo + R'CH - CH2 ~ R' - C - C
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! 0 0 N - R
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~ N~substituted 2-oxazolidone :
As described by P. I. Kordomenos, K. C. Frisch and J. E.
Kresta, J~_Coatinqs Tech., Vol. 55, No. 700, pages 49-61 (1983), polyoxazolidones having terminal epoxide groups can also be used in combination with customary epoxy resin har-deners as coating agents. The reaction also provides for - the preparation of polyoxazolidone isocyanates and corres-ponding prep~lymers, which can be crosslinked in the custom-ary manner. The coatings exhibit a good hardness as well as good resistance to solvents and heat.
The present invention, accordingly, relates to a ; process for the preparation of cationic binders, primarily for electrodeposition coatings based on modified epoxy resin-amine adducts, characterized in that -~- 4 '`''`

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:~ (A) 60 to 80% by weight, preferably 65 to 75% by weight, of an epoxy resin component consisting of (Aa) 60 to 98% by weight, preferably 80 to 97% by weight, of at least one aromatic and/or aliphatic diepoxy resin having an epoxide equivalent weight of between l90 and 500, and (Ab~ 2 to 40~ by weight, preferably 3 to 20~ by weight, of at least one epoxide compound which is modified by N-substituted mono- and/or bis-2-oxazolidone groupings, such as are obtained by reaction of ' glycidyl groups with isocyanate groups, and has the general formula -R3-CH2-CH - fH2~H2 - fH-CH2-R2 : l N - R1 ~
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C C (I) -: O O
~ or R3-CH2-fH - fH2 \ /
C (I~) . O
wherein R1 represents the remaining radical or moiety of a ~cycl~)aliphatic or an aromatic diisocyanate, R2 represents the remaining radical or moiety of an .i .. ~

- 2502/~JS-3480 2~3~37~fi aliphatic monoglycidyl ether or an aliphatic monoglycidyl ester or a radical R3, R3 represents the remainin~ radical or moiety of an (aromatic)-aliphatic or aromatic diglycidyl ether, and R4 represents the remaining radical or moiety of a (cyclo)aliphatic or an aromatic monoisocyanate, are reacted with -(B) 20 to 40% by weight, preferably 25 to 35% by weight, of an amine component consisting of -(Ba) 0 to 20% by amine equivalence, preferably o to 15%
by amine equivalence, o~ at least one primary alkylamine and/or alkanolamine, (Bb) 25 to 55% by amine equivalence, preferably 35 to 50% by amine equivalence, of at least one second-ary alkylamine and/or alkanolamine, (Bc) 20 to 50% by amine equivalence, preferably 25 to 45% by amine equivalence, of at least one primary-tertiary alkyldiamine and :~ (Bd) 5 to 25% by amine equivalence, preferably 10 to 20% by amine equivalence, of a disecondary amine compound of 2 mol of a compound which is the reaction product of diprimary di- or polyamines with aliphatic monoglycidyl and/or monoepoxide compounds with one mol of a diepoxide compound, .~ .

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wherein the totals of the percentage ~igures of components A and B or components (Aa) and (Ab) or components (Ba), (Bb), (Bc) and (Bd) must in each case give 100, to provide an adduct which is free from epoxide groups and has a mole-cular weight of from 2000 - 18,000 (weight-average), a glass transition temperature of between ~20C and ~45~C, and a basicity corresponding to an amine number of at Ieast 20 mg KOH/g, with the proviso that the epoxy resin components (Aa) and (Ab) are reacted with the amine components (Ba), (Bb), (Bc) and (Bd) at 60C to ~0C in a 55-75% strength partial solution in glycol ethers, the reaotion with amine component tBc) preferably being carried out last, and that after the end of all the additions, the reaction temperature is in-creased to a maximum of 120C to bring the reaction to com-pletion.
The invention also relates to the cationic binders for coatings prepared by the process of this invention, and to their use in combination with crosslinking components in cathodic electrodeposition coatings.
As a result of the modifications according to the pr~sent invention, on the one hand oxazolidone segments which have high glass transition temperatures, coupled with a low molecular weight, are introduced, and, on the other ' hand, the diamine modifiers (Bd) have a high molecular weight, coupled with a low glass transition temperatuxe.

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Because of this combination, the electro-dipping coatings according to the invention have excellent electrical proper-ties, such as a high wet film resistance, coupled with a good film build-up, and therefore excellent throwing power.
The crosslinked films of the coatings have very good resis-tance properties, and, particularly, excellent corrosion protection on the edges of the workpiPces.
Starting materials for the binders prepared ac-cording to the present invention which are used as component tAa) are aromatic or aliphatic diepoxy resins, for example diepoxy resins based on diphenols or polyalkylene glycols, such as are described in the relevant literature for the preparation of epoxy resin-amine adducts which are used as cationic binders for coatings, and are available from var-ious manufacturers. This group also includes the products modified in various ways by chain lengthening. The di-epoxide compounds employed according to the invention have epoxide equivalent weights of between 190 and 500.
The epoxy resin components (Ab) are mono-or di-epoxide compounds which are modified by N-substituted mono or bis-2-oxazolidone groupings, such as are obtained by reaction of glycidyl groups with isocyanate groups, and can be defined by the followin~ general formulae:
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R3-CH2-1H - fH2 fH2 ~ IH-CH2-R2 0 N - Rl - N 0 C C (I) O O
or R3--CH2--fH - ,I,H2 \ / - R4 C (II) wherein R1 represents the remaining radical or moiety of a (cyclo)aliphatic or an aromatic diisocyanate, R2 represents the remaining radical or moiety of an aliphatic monoglycidyl ether or an aliphatic mono-- glycidyl ester or a radical R3, R3 represents the remaining radical or moiety of an : (aromatic~-aliphatic or aro~atic diglycidyl ether, and R4 represents the remaining radical or moiety of a (cyclo)aliphatic or an aromatic monoisocyanate.

The glycidyl groups which take part in the reac-tion, such a~ are defined in the formulae (I) and (II) by : the radical R3, originate from diepoxide compounds. The products are essentially commercially available products of the bisphenol A or F type, aliphatic diepoxide compounds . ;. . :
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based on polyalkylene glycol, or aromatic-aliphatic diepox-ide compounds, for example based on a bisphenol A modified 1 with polyoxypropylene glycol.
The monoglycidyl compounds characterized by a radical R2 in ~ormula (I), as monofunctional co~pounds, as is the case with the compounds of the formula (II), are pre-: ferably employed only in combination with the corresponding difunctional compounds (formula (I), R2 = R3).
Monoglycidyl compounds which are employed herein are the monoepoxide compounds having an aliphatic radical of 8 to 20 carbon atoms, such as alkyl glycidyl ethers or esters and, in particular, the known glycidyl esters of KOCH
acids.
The known aliphatic, cycloaliphatic, and aromatic .
diisocyanates can be employed as diisocyanates of which the remaining radical is expressed in formula tI) by Rt. Exam ples are hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, toluylane diisocyan-ate (for example as a commercially available isomer mixture with an 80~ ~ontent of the 2,4-isomer), diphenylmethane diisocyanate or meta-tetrame-thylxylylene diisocyanate.
tCyclo)aliphatic monoisocyanates, such as octa-decyl monoisocyanate, or phenyl isocyanates are employed as the monoisocyanatss (radical R4 in the formula (II))~

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2502/US-3480 2~ 86 For the preparation of component (Ab), the epoxy resins are dehydrated before the reaction, for example by aæeotropic distillation with an entraining agent, and are then dissolved in a solvent which is inert towards the reac-tion, and 0.5 to 5 mol ~, based on the isocyanate groups to be reacted, o~ lithium bromide are added as a catalyst. The isocyanate compounds are reacted with tha glycidyl compounds at reaction temperatures of 90 to 160C. The course of the reaction is monitored by the decrease in the content of NCO-groups and the synchronous decrease in the content of oxi-rane groups. The resulting products have an absorption in the IR-spectrum at a wave number of 1720 - 1760 cml which is typical of the carbonyl vibration of the oxazolidone grouping.
Components (Aa) and (Ab) are employed in the further reaction with the amines of component ~B) in a ratio of 60 to 98~ by weight, pre~erably 80 to 97% by weight, of component (Aa) and 2 to 40% by weight, preferahly 3 to 20 by weight, of component (Ab).
Components (A) and (B) are reacted at a ratio of from 60 to 80~ by weight, preferably 65 to 75% by weight, of component ~A3 and 20 to 40% by weight, preferably 25 to 35%
. by weight, of component (B) to give an adduct which is free from epoxide groups.

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The amines of group (Ba) containing 0 to 20~ by amine equivalence, pre~erably 0 to 15~ by amine equivalence, of component (B), as well as the amines of group (Bb) con-taining 25 to 55~ by amine equivalence, preferably 35 to 50%
by amine equivalence, of component (B) and the amines of group (Bd) containing 5 to 25~ by amine equivalence, prefer-ably 10 to 20~ by amine equivalence, of component (B) are reacted with the epoxy resin component A, consisting of (Aa) and (Ab) in a first reaction stage at 60C to 80C in a 55 -75~ strength partial solution in glycol ethers until the NH-functionality has been converted completely. The method of determination of the sum of basic nitrogen atoms and free oxirane groups (EPA-value) is used to monitor the course of the reaction.
The free epoxide groups which remain in this re-action step are advantageously subsequently reacted in a second reaction stage at 60~C with the amines of group (Bc), which are present in component (B) in an amount of 20 to 50 by amine equivalence, preferably 25 to 45% by amine equiva-lence. The reaction is then conducted at 100 - 120C until all the oxirane groups have baen converted completely.
Amines of group (Ba) which are employed are prima-ry alkylamines, such as n-butylamine, n-hexylamine, octyl~
amine, mono-2-ethylhexylamine and C10-C18-alkylamines, fatty amines and/or primary alkanolamines, such as monoethanol-:
.

20~3~3';'86 amine, l-amino-2-propanol, 2-aminobutan-1-ol, 2-amino-2-ethylpropane-1,3-diol and 2-(2-hydroxyethoxy)-1-ethylamine.
Group (Bb) includes secondary alkylamines, such as diethylamine, di-n-propylamine, di-n-butylamine, diiso-propylamine, diisobutylamine, dicyclohexylamine, di-2-ethyl-hexylamine and morpholine, and/or secondary alkanolamines, such as diethanolamine, diisopropanolamine, n-butylethanol-amine, cyclohexylethanolamine, and 2-(N-methylamino)ethanol.
Group (Bc) includes primary-tertiary alkyldi-amines, such as 1-amino-3-dimethylaminopropane ~N,N-di-methylaminopropylamine), l-amino-3-diethylaminopropane ~N,N-diethylaminopropylamine), and l-diethylamino-4-amino-pentane.
The amines of group (Bd) are disecondary amine compounds which are obtained by reaction of diprimary ali-phatic di- or polyamines with aliphatic monoglycidyl and/or monoepoxide compounds. These can be built up to disecondary polyaminopolyols in a further reaction in a ratio of 2 mol of amine compound to 1 mol of a diepoxide compound. Prod-ucts of this type are described in detail in EP~A2-0,355,654, corresponding to U.S. Patent No. 4,992,516. Compound~ which are the reaction product of 1 mol of diethylenetriamine and 3.1 mol of ethylhexyl glycidyl ether are preferably employed for the process according to the invention.

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250~/US-3480 Z~3~7~6 In another preferred ~orm, compounds which are the reaction product of 2 mol o~ a disecondary amine com-pound, consisting of 1 mol of diethylenetriamine and 3.1 mol of ethylhexyl ~lycidyl ether, with 1 mol of a bisphenol A-epichlorohydrin epoxy resin (epoxide e~uivalent weight lso) are employed.
The amines used in component (B) impart to the end product, after protonation, the required water-dilutability and in the reaction with component A lead to the molecular weight distributions characteristic of the end products, while at the same time enlarging the molecule.
The epoxy resin-amine adducts prepared according to the invention have a molecular weight of 2000 to 18,000 (weight-average) or 1500 to 3000 (number-average). Their glass transition temperature is between +20C and +45C.
For good solubility after protonation, a basicity corres-ponding to an amine number of at least 20 mg KOH/g is neces-sary, which should be taken into account when formulating the resin batch.
After the reaction, the organic solvent, if used, can be removed proportionately in vacuo, if desired. This process stage can be carried out only after partial neutral-ization of the batch and after dilution with water. In this process variant, materials wnich have only low contents o~
organic solvents and therefore also comply with strict en-.

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vironmental regulations, for example the low-VOC regulations of the USA, are obtained.
Amounts of acids of 20 to 45 mMol/100 g binder (solid resin) are required for the neutralization for the products prepared by the process according to the invention in order to obtain a stable and sedimentation-free aqueous solution or emulsion which is suitable for electrodeposition coating practice. The products according to the invention have excellent dispersibility because of their build-up.
The processibility and the electrical properties of the binders are advantageously influenced by the low degree of neutralization.
The binders prepared by the process according to the present invention are used in combination with cross-linking components. The products which lead to crosslinking by transesterification reactions are described, for example, - in EP-Bl-0,012,463, corresponding to U.S. Patent No.

4,332,711; DE-Al-3,315,~69; Austrian Patent No. 372,099, corresponding to U.S. Patent No. 4,458,054; and Austrian Patent No. 379,602, corresponding to U.S. Patent No.
4,523,007, can be used in the presant invention. Cross-linking by blocked isocyanates or amino resins, if appro-priate, using corresponding catalysts, can also be used.
Tha stoving temperatures for the deposited films are between 140~C and 190~C, depending on the hardening system employed.

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: The preparation of the bath material for the electrodeposition coating, the pigmentation and the neutral-: i7ation and dilution of the coatings are known to a person skilled in the art and do not require more detailed descrip-tion. This also applies to the coating operation and the hardening of the films deposited.

DETAILED DESCRIPTION AND
PRESENTLY PRE~ERRED EMBODIMENTS
The following examples illustrate the invention without limiting it in its scope. All the data in parts or percentages relate to weight units, unless otherwise stated.
The following abbreviations are used in the exam-ples:

MP........ methoxypropanol EP........ ethoxypropanol CE........ versatic acid glycidyl ester . Cardura~ E (Shell) EEW 475.. epoxy resin based on bisphenol A-diglycidyl ether haviny an epoxy resin e~uivalent weight o~ 475 (Epikote~ 1001, Shell), 75% strength in MP
- EEW 190... epoxy resin based on bisphenol A-diglycidyl ether having an epoxide e~uiva}ent weight of 190 ~Epon~ 828, Shell) EEW 200... epoxy resin based on a diglycidyl ather which - is modified with polyoxypropylene glycol and :: having an epoxide equivalent weight of 200 (DER~ 732, Dow Chemical) .
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~~ 2502/US-3480 2~3~fi EEW 320... epoxy re~in based on a diglycidyl ether which is modified with polyoxypropylene glycol and has an epoxide equivalent weight of 320 (DER~
736, Dow Chemical) EEW 350... epoxy resin based on bisphenol A-diglycidyl ether which is modified with polyoxypropyl glycol and has an epoxide equivalent weight of 350 (BPP 350~, Sanyo Chemical) TDI....... toluylene diisocyanate 80/20 (commercially available isomer mixture) IPDI...... isophorone diisocyanate MDI....... diphenylmethane diisocyanate HMDI...... hexamethylene diisocyanate TMHMDI.... trimethylhexamethylene diisocyanate TT........ dimeric toluylene diisocyanate (Bayer) ODI....... octadecyl mor.oisocyanate MEHA...... mono-2-ethylhexylamine DOLA...... diethanolamine DMAPA..... N,N-dimethylaminopropylamine DEAPA..... N,N-diethylaminopropylamine The following methods are used in the examples for the determination of the NCO-conten~ or the oxirane : content (EPA-Value):
NCO-Value:l About 0.5 - 4 g of resin, corresponding to the NCO-value to be expected, are dissolved in 30 ml of diglycol dimethyl ether, 10 ml of Kappelmeyer's rea~ent are added, and the mixture is homogenized for one minute. After addition of three drops of bromophenol blue indicator solu-tion, the mixture is titrated from blue to yellow using 0.5 .; N a~ueous HCl (value A). ~ blank value is carried out in :;

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parallel, including all the reagents except ~or the amount of resin weighed out (value B).
B - A
-- NCO-Value (%) = x 2.1 amount weig~ed out (g) Kappelmeyer's reagent: 64.6 g pure diisobutylamine 864 g diglycol dimethyl ether ~- Calculation of the amount of resin weighed out in grams based on expected NCO-value:
0.5 - 1.0 g ..... if ..... 10 - 15%
2 - 4 g ....... if ..... below 1%

EPA-Value: Method for determination of the content of oxirane groups. Any amino groups present are al50 deter-mined in milliequivalents per gram of sample by this method.
0.2 - 0.4 g of resin are accurately weighed (to the milligram~ and are ~used in five drops of methoxypro-panol. After cooling, 25 ml of a mixture of methylene chloride and glacial acetic acid (4:1 parts by volume) are added and the resin is dissolved, while heating gently.
- 0.5 g of tetrabutylammonium iodide and three drops of cry-. .
i stal violet solution are then added at room temperature.
The mixture is titrated from blue-violet to grass-green ~no blue tint) using 0.1 N perchloric acid solution in glacial : acetic acid.
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~ A blank value (without resin) is determined in the ,~ . .
`~ same manner.

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(A B) x 0.1 x F
EPA-Value =
amount weighed out tg) A = ml of 0.1 N perchloric acid ~or the sample ' B = ml of 0.1 N perchloric acid for the blank value F = 0.1 N perchloric acid solution factor Determination of 0.1 N Perchloric Acid Factor (F):
About 200 mg of potassium hydrogen phthalate (analytical grade) are accurately weighed to 0.1 mg into a conical flask. After addition of 30 ml of glacial acetic acid and three drops of crystal violet solution, titration is carried ;~ out from blue-violet to grass-green using the approximat,ely 0.1 N perchloric acid solution.

'I amount of potassium hydrogen phthalate weighed out F =
consumption x 20.422 The epoxide equivalent weight (EEW) in grams of solid resin, that is to say the amount of reaction product .' (in grams of solid resin) which contains one epoxide group, is calculated as follows from the EPA-value:
' Epoxide equivalent weight solids content x 10 (grams of solid resin) - EPA
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' . Preparation of Epoxy Resin Component Ab) Emplo~ed Accordinq~to I~vention ~efore reaction with the isocyanate component, ,'.' the epoxide compounds employed are freed from traces of . 19 .
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water by azeotropic distillation, preferably using xylene or toluene as the entraining agent. The entraining agent is then removed by vacuum distillation, and the epoxide com-pound is diluted with the amount of diglycol dimethyl ether needed to achieve the reaction dilution. This solution to which the stated amount of catalyst has been added is heated to the reaction temperature, while stirring. The isocyanate component is added in the course of two hours, and the reac tion is carried out at the stated temperature until complete conversion of the isocyanate group is achieved; that is to say, to an NC0-content of less than 0.1~. The starting substances, reaction conditions, and characteristics of the intermediate products are summarized in Table 1 as follows.

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Preparation of Component (Bd) Employed Accordinq to Invention Com~onent fBd)l: 577 g (3.1 mol) of 2-ethylhexyl gly-cidyl ether are added to a solution of 103 g tl mol) of diethylenetriamine and 170 g of methoxypropanol at 60C in the course of two hours, and the components are reacted to an EPA-value of 3.70 and a refractiYe index n20/d of 1.4600.
A mixture of 190 g (1 epoxide equivalent) of a bisphenol A-epichlorohydrin epoxy resin (EEW 190) and 49 g of methoxy-propanol is then added at 60C in the course of two hours.
The reaction is continued to an EPA-value of 2.70 and a refractive index of 1.4790. A solution of 100 g of the 80%
strength reaction product and 30 g of methoxypropanol has a viscosity (DIN 53211/20C) of 60 - 80 seconds.
Component (Bd)2: 577 g (3.1 mol) of 2-ethylhexyl gly-cidyl ether are added to 103 g tl mol) of diethylenetriamine and 170 g of methoxypropanol at 60C in the course of two hours, and the components are reacted at this temperature to an EPA-value of 3.53. A solution of the 80~ strength resin has a refractive index of n20/d of 1.4580.
Examples 1 to 9 The binders of this invention are prepared in the following manner in accordance with the data summarized in Table 2. In a first reaction stage, the epoxy resin com-ponents (Aa) and (Ab) are dissolved in methoxypropanol or ethoxypropanol in a suitable reaction vessel and are reacted '' . , :

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with the amine components (Ba), (Bb) and (Bd) at 60C until the stated EPA-value 1 is reached.
-~: The product is then reacted w.ith the amine com-ponent (Bc), also at 60C; and a~ter increasing the tempera-ture to 120C, the reaction is ended when the stated EPA-value 2 is reached.
Table 2 is as follows:
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Example Component 1 ~X! 2 ~X) 3 (X~
EEW 475 (75%) 601.3 (0.95) 443 (0.7) 697 (1.1) ` (Aa) EEW 350 -- 525 (1.5) --EEW 190 -- 285 (1.5) 570 t3.0) 129 (0.20) 683 (0.70) 415 (0.3) (Ab) . (Ab)lf70~) (Ab)2f80%) (Ab)3~60%) -- 32.3 (0.5) 32.3 (0.5) (Ba) MEHA MEHA
45.2 (0.43) 189 (1.8) 147 (1.4) (Bb) DOLA DOLA DOLA
~ 119 ~0.28) 652 (0.6) 652 (0.6) .. : (8d) (Bd)2(80~) (Bd~1(80%) (Bd)1(80%) Solvent 140.2 MP 974 MP 960 MP
~ *EPA-Value 1 1.30 _ 1.42 l.S4 : 16.3 (0.32) 78 (1.2) 104 (1.6) (B~) : _ DMAPA . DEAPA DEAPA
,, ~ .
` **EPA-Value 2 1.14 1.30 1.41 '~

.: Solids content. % 65 65 60 ,~
. Viscosity Measurement 100 + 50 MP 100 ~ 40 MP 110 ~ 30 MP DIN 53211/ Solution (XX) . 20C
Flow Time 230 s 80 s 250 s ***GPC, Ultrastyragel Weight-Average Mw 8976 2508 9974 ~ Number-Aver~qe Mn 2295 1542 2586 ,~
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2502/US-3480 2~387~6 T A B L E 2 (Continued) Example Com~onent 4 (X) 5 (X~6 (X~
EEW 475 ~75%) 570 (0.9) 1824 (2.88) 2150 (3.39) (~a) EEW 350 ~ 147 (0.42) EEW 190 _ 570 (3.0) 315 (1.66) --383 (0-5) 253 (0.19) 110 (0.09 (Ab) (Ab)4(60~) (Ab)5(60%~ LAb~6(60%) 48-4 (0.75) 53,5 (0,4~5) __ (Ba) MEHA MEHA
126 (1.2) 189 (1.8) 158 (1.5) (Bb) DOLA DOLA DOLA
380 (0.35) 652 (0.6) 652 (0.6) (Bd) (Bd)1(80%~ ~Bd)l(80%) (Bd)lt80%) ; Solvent 410 MP 460 MP _ 1023 EP
*EPA-Value 1 1.90 1.52 1.20 117 (1.8) 78 (1.2) 97.5 (1-5) ;~ (Bc) DEAPA DEAPA ~EAPA
.

**EPA-Value 2 1.70 1.30 1.11 .~
Parameters: `~
Solids Content, ~ 70 70 60 Viscosity Measurement 93 ~ 47 MP 81 + 59 EP 95 + 45 EP
DIN 53211/ Solution (XX) 20~
, Flow Time 130 s 110 s 145 s ***GPC, Ultrastyragel ' Weight-Average Mw 5624 5419 6873 Number-Averaqe Mn 1571 1776 2049 . ~

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- 2502/US-3480 2038~7~6 T A B L E 2 (Continued) Example Component _ 7 (X~) 8 (x) 9 (X) EEW 475 (75%) 443 (0.7) 1892 (2.99) 1963 (3.1) (Aa) EEW 350 525 ~1.5)291 (0.83) --EEW 190 285 (1.5 ~ -- --410 (0.7)178 (0.18) 394 (0.~) (Ab) _ (Ab)7(70~)(Ab)8(80%)fAb)9~70%) 38.7 (0.6) -- --(Ba) MEHA
210 (2.0) 168 (1.6) 116 (1.1) (Bb) DOLA DOLA DOLA
: 326 (0.3) 761 (0.7) ~52 (0.6) , (Bd) (Bd!1(80~! (Bd)1(80%)(Bd!1(80~) Solvent 788 EP 1139 EP 613 EP
~` *EPA-Value 1 1.85 1.15 1.26 ,` 78 (1.2) 104 (1.6)117 (1.8) (Bc) - _ DEAPA DEAPA DEAPA
: ' **EPA-Value 2 1.32 1.13 1.24 .~
Parameters:
Solids Content, % 65 60 65 Viscosity Measurement 108 + 32 MP 95 -~ 45 EP 90 + 60 EP
DIN 53211/ Solution ~XX) - 20~C
_Flow T me 95 s 100 s 122 s ***GPC, Ultrastyragel :` Weight-Average Mw 3768 5811 10205 ~ Number-Averaqe Mn 1645 _ 1824 2309 :~ .

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~ 2502/US-3~80 ~038~86 , .................................................................. .
'~' The resulting reac~ion products are characterized by their solid resin content, the viscosity, and the molecu-lar weight distribution as determined by gel permeation - chromatography (GPC).

` (X).... amounts stated in parts by weight, the equivalents of oxirane or NH-groups which react during the synthesis are stated in parentheses.
(XX)... the composition of the measurement solution is stated as (grams of resin solution + grams of solvent).
*...... EPA-Value 1: milliequivalents of oxirane groups and basic nitrogen groups per gram of resin solu-tion.
**..... EPA-Value 2: milliequivalents of basic nitrogen groups per gram of resin solution:
EPA-Value 2 x 560 amine number in mg KOH/g =
solids content in %
` ***.... the gel permeation analysis was carried out using tetrahydrofuran as the eluting agent on a unit . . .
consisting of an LKB-pump 2150, 3 Ultrastyragel columns (Waters) with an exclusion volume of 500, 1000, and 10,000 A and a differential refractom-eter 12401 (Waters~, in comparison with a poly-styrene calibration standard.
' Crossli~kina Component VK 1 - In a reaction vessel with equipment suitable for the azeotropic process and a bubble tray column for removal of the alcohol component formed dur-ing the partial transesterification, 29.7 g (0.9 mol) of 91%
pure paraformaldehyde are added in portions to a mixture of .~ ' .
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- 2502/US-34~0 ~38~86 160 g (1 mol~ of diethyl malonate, 0.34 g (0.004 mol) o*
piperidine and 0.22 g (0.004 mol) of 85% strength formic ; acid at 800C such that a temperature of 95C is not exceeded ` when the exothermic reaction starts. The reaction mixture ; is stirred at 95C until the paraformaldehyde has dissolved completely. The temperature is increased to 110C in the course of two hours. When the temperature reaches 110C, a total of 9 g of water are distilled off together with spe-cial grade petroleum (boiling range 80C - 120C) as the entraining agent. The entraining agent employed is subse-quently removed by applying a vacuum.
; After addition of 22.8 g (0.3 mol) of propylene 1,2-glycol, the batch is heated up to the start of distil-lation (140C - 150C). As the temperature rises, 27 parts tO.6 mol) of ethanol are distilled off. The resulting prod-uct has a solid resin content (120C, 30 minutes) of about 92%, an OH number of less than 5 mg KOH/g, an intrinsic vis-cosity number of about 5.2 ml/g (20c, dimethylformamide) and a refractive index n20/d of 1.4670.
Crosslinkinq Component VK 2 - In accordance with the process described for VK 1, a mixture of 134.4 g (0.84 mol~
of diethyl malonate, 0.286 g ~0.0034 mol) of piperidine and 0.185 g (0.0034 mol) of 85% strength formic acid is reacted with 13.86 g (0.42 mol) of 91% pure paraformaldehyde, a total of 9.24 g (0.51 mol~ of water bein~ distilled off.

~' ' ' . 2502/US 3480 Z0~7l~

. .
The product has a solids content of 78~ (120C, 30 minutes).
The refractive index has a value of n20/d = 1.437.
134 g (1 mol) o~ trimethylolpropane are then added and the mixture is heated up to the start of distillation (140 - 150~C). As the temperature rises, 23 ~ (0.5 mol) of ethanol are distilled off. When the stated amount of dis-tillate is obtained, the mixture is diluted with 263 g of diethylene glycol dimethyl ether (DGDME) and cooled to 30C.
800 g ~2.5 mol or NC0-e~uivalents) of a reaction product of 2.5 mol of toluylene diisocyanate (commercially available isomer mixture) and 2.5 mol of Qthylene glycol monohexyl-ether are added at 30C in the course of six hours. The temperature is increase to 100C in the course of a further four hours, and the reaction is carried out at this tPmpera-ture up to an NC0-content of less that 0.01 milliequivalent per gram of sample.
The resulting product having a solid resin content of 80% (120C, 30 minutes) has a refractive index n20/d of 1.507 and a viscosity (10 g of resin solution + 4 g of DGDME) of E - F (Gardn2r~Holdt).
Crossli~kinq Component VK 3 - Reaction product of .
134 g (1 mol) of trimethylolpropane with 851 g (2.8 mol3 `: of a TDI, halfblocked with 2-ethylhexanol, in a 70~ strength ` DGDME solution.
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: Comparison Example 1 tProduct Accordinq to RP-A2-0,355.654) 772 g of MOD 3) (corresponding to 0.6 NH-equi-valents)~ 570 g (3.0 epoxide equivalents) of a bisphenol A
diepoxy resin (EEW 190), 77.4 g (1.2 NH-equivalents of 2~ethylhexylamine and 162 g of methoxypropanol are reacted in a suitable reaction vessel at 60C in a first reaction stage until conversion of the NH-functionality is complete, determined by reaching an EPA-value of 1.99. 1330 g ~2.1 epoxide equivalents) of a 75% strength solution af a bisphe-nol A diepoxy resin (EEW 475) in methoxypropanol and 189 g (1.8 NH-equivalents) of diethanolamine are then added, and the mixture i5 reacted again until the NH-functionality is converted, determined by reaching an EPA-value of 1.63. The remaining oxirane groups are reacted in a third reaction stage with 78 g (1.2 NH-equivalents) of N,N-diethylamino-propylamine at 60C for two hours, at 90C for a further hour, and at 120C for a further three hours, to an.EPA-value of 1.49; and the product is diluted with methoxypro~
panol to a solid resin content of 65% by weight. The vis-cosity (DIN 53211/20C) of a resin solution diluted to a solid resin content of 46% by weight with methoxypropanol is 160 seconds. The weight and number averages determined from gel chromatograms are: Mw = 8452, Mn = 1431.

) MOD 3: 577 g (3.1 mol) o~ 2-ethylhexyl glycidyl ether are added to 103 g (1 mol) of diethylenetriamine : ' : .

:

~ 2502/US-3~80 2~3~

., and 170 g of methoxypropanol at 60 3 C in the course of two hours, and the components are reacted at this tem-perature to an EPA-value of 3.53. A mixture of 87 g o~
methoxypropanol and 350 g (1 epoxide equivalent) of a diepoxy resin based on bisphenol A which is modiied with polyoxypropylene glycol (BPP 350, Sanyo Chemical) is then added at 60C in the course of two hours, and the reaction is continued to an EPA-value of 2.33.
~' .
; A solution of 100 g of the 80% strength resin and 30 g of methoxypropanol has a viscosity (DIN 53211/20C) of 60 - 70 seconds.
80 parts by weight (solid resin) of the product described as Comparison Example 1 are homogenized with 20 parts by weight (solid resin) of the Crosslinking Component VK 2 at 60C for 30 minutes and, after neutralization with 35 mMol of formic acid per 100 g of solid resin, the mixture is further processed to a coating in the manner described.

Comparison Example 2 lProduct Accordinq to Austrian Patent No. 381.115~
1627 g (3.43 equivalents) of epoxy resin EEW 475 are reacted with 226 g (0.24 equivalent) of carboxy-func-tional modifier1) in the presence of the solvent methoxy-propanol at a solid resin content of 85~ in a suitable reaction vessel at 110~C to an acid number of less than 0.5 mg KOH/g. ~fter dilution of the batch to a solids con-tent of 70% with further solvent, 94.5 g (0.9 NH-equiva-lents) of diethanolamine, 67.5 g ~0.9 NH e~uivalents) of ~ 31 ;~
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-~2502/us-3480 20387~

, , N-methylethanolamine and 78 g (1.2 NH-equivalents~ of N,N-diethylaminopropylamine are added at 60C in -the course of two hours. The components are then reacted at 90~C for four hours, 238 g (1.19 equivalents) of epoxy resin EEW 200 are added and the components are reacted at 120~C for six hours, until all the glycidyl groups have been consumed. The re-action product is diluted to a solids content of 65% with MP.
For Comparison Example 2, 70 parts (solid resin) of the reaction product are reacted with 30 parts (solid . resin) of Crosslinking Component VK 1 at 120C for one hour.
After neutralization with 40 mMol of formic acid per 100 g of solid resin, a coating is prepared in the manner described~

1) Carboxy-functional modifier: .Polyester of 3 mol of trimethylolpropane, 2 mol of adipic acid, 1 mol of - isononanoic acid, and 1 mol of tetrahydrophthalic anhy-dride (acid number: 65 mg KOH/g, carboxyl equivalent weight 942 g).

Comparison Example 3 `` (P~oduct Accordinq to EP-A2-0,218,812) 228 parts of bisphenol A (1 mol) are reacted with 260 parts of di~thylaminopropylamine (2 mol) and 66 parts of 91% pure paraformaldehyde (2 mol) in the presence of 131 parts o~ toluen~, as the azeotrope entraining agent, at 90 to 130C in a suitable reaction vessel until 42 parts of ,' '' '"

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2502/US-34~0 Z 0 ~ ~ J~8~

water of reaction have been separated off. After addition of 152 parts of diethylene glycol dimethyl ether and cooling to 30C, 608 parts (2.0 mol) of a toluylene diisocyanate halfblocked with 2-ethylh~xanol are added in the course of 45 minutes.
As soon as all the isocyanate groups have been consumed, 500 parts (2 mol) of the glycidyl ester of a saturated tertiary C9-C1~-monocarboxylic acid which has been dissolved in 300 parts of diethylene glycol dimethyl ether are added to 140Q parts of this solution, and the components are reacted at 95 to 100C to an epoxide value of zero.
After cooling to 80C, 210 parts tl mol) of trimethylhexa-methylene diisocyanate, dissolved in 53 parts of diethylene glycol dimethyl ether, are added in the course of 30 min-utes. After checking that the reaction is complete, 0.6 part/100 g o~ solid resin of dibutyltin dilaurate (calcu-lated as the metal~ is added to the product and the product is converted into the water-dilutable form by addition of 35 millimol of formic acid/lO0 g of solid resin.

Testin~ of Products According to Examples 1 - 9 In Coati~n~s Which Can Be Deposited Cathodically The products prepared according to the invention are subjected to precondensation in the ratios stated in Table 3 with a crosslinking component, as above defined, in 60% strength solution in methoxypropanol or ethoxypropanol .

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in accordance with the conditions stated. coatings are pre-pared in the customary manner from these binder solutions in accordance with the formulation -- 100 ...... parts of binder (solid resin) 36.5 ..... parts of titanium dioxide 3 ........ parts of lead silicate pigment 0.5 ...... part of carbon black and, after protonation with the amount of acid stated in Table 3, are diluted to a solids content of 18% with de-ionized water. Table 3 is as follows:

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~ 2502/US-3480 Z038 ~86 Lead in the form of lead octoate was employed in an amount of 1 part of lead (metal) per 100 parts of binder solid resin as the catalyst for the hardening.
For Compari50n Example 3, tin in the form of dibutyltin dilaurate was employed in an amount of 0.6 part/100 g of solid resin ~calculated as the metal).
The coating is deposited onto zinc-phosphated steel sheets at a bath temperature of 28c over a coating time of two minutes. The sheets coated in this way were then stoved at 160C for 30 minutes. The test results are summarized in Table 4 as follows:

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- 2502/US-3480 203~7~6 The test results of the products according to the present invention in respect to corrosion protection on the edges are particularly significant in direct comparison with the properties of comparison products from patent applica-tions EP-A2-0,355,654, corresponding to U.S. Patent No.
4,992,516; Austrian Patent No. 381,115, and EP-A2-0,218,812, corresponding to U.S. Patent No. 4,845,171; which are consi-dered to be very good and which are built up in a similar manner but without oxazolidone structural units.
As will be apparent to one skilled in the art, various modifications can be made within the scope of the aforesaid description. Such modi~ications being within the ability of one skilled in the art form a part of the present invention and are embraced by the appended claims.

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Claims (9)

1. Process for the preparation of cationic bin-ders based on modified epoxy resin-amine adducts comprising reacting -(A) 60 to 80% by weight of an epoxy resin component con-sisting of (Aa) 60 to 98% by weight of at least one aromatic and/or aliphatic diepoxy resin having an epoxide equivalent weight of between 190 and 500, and (Ab) 2 to 40% by weight of at least one epoxide com-pound which is modified by N-substituted mono-and/or bis-2-oxazolidone groupings, which are ob-tained by reaction of glycidyl groups with iso-cyanate groups, and having the general formula - (I) or (II) wherein R1 represents the moiety of a (cyclo)aliphatic or an aromatic diisocyanate, R2 represents the moiety of an aliphatic monoglycidyl ether or an aliphatic monoglycidyl ester or a radical R3, R3 represents the moiety of an (aromatic)-aliphatic or aromatic diglycidyl ether, and R4 represents the moiety of a (cyclo)aliphatic or an aromatic monoisocyanate, with (B) 20 to 40% by weight of an amine component consisting of (Ba) 0 to 20% by amine equivalence of at least one primary alkylamine and/or alkanolamine, (Bb) 25 to 55% by amine equivalence of at least one secondary alkylamine and/or alkanolamine, (Bc) 20 to 50% by amine equivalence of at least one primary-tertiary alkyldiamine, and (Bd) 5 to 25% by amine equivalence of a disecondary amine compound of 2 mol of a compound resulting from the reaction product of diprimary di- or polyamines with aliphatic monoglycidyl and/or monoepoxide compounds with one mol of a diepoxide compound, wherein the totals of the percentage figures of components A
and B equals 100 to give an adduct which is free from epox-ide groups and has a molecular weight of from about 2000 -18,000 (weight-average), a glass transition temperature of between +20°C and +45°C, and a basicity corresponding to an amine number of at least 20 mg KOH/g, with the proviso that the epoxy resin components (Aa) and (Ab) of component A are reacted with the amine components (Ba), (Bb), (Bc) and (Bd) of component B at 60°C to 80°C in a 55-75% strength partial solution in glycol ethers, and that after the end of all the additions, the reaction temperature is increased to a maxi-mum of 120°C to bring the reaction to completion.

2. The process of claim 1 wherein the resin-amine adduct contains 65 to 75% by weight of the epoxy resin component (A) and 25 to 35% by weight of the amine component (B), and wherein in component (A) (Aa) is present in an amount of from 80 to 97% by weight and (Ab) is present in an amount of from 3 to 20% by weight; and wherein in compo-nent B (Ba) is present in an amount of from 0 to 15% by amine equivalence, (Bb) is present in an amount of from 35 to 50% by amine equivalence, (Bc) is present in an amount of from 25 to 40% by amine equivalence, and (Bd) is present in an amount of from 10 to 20% by amine equivalence.

3. The process of claim 2 wherein the reaction with amine component (Bc) is carried out after reaction with amine components (Ba) and (Bb).

4. The cationic binders of claim 1.

5. The cationic binders of claim 2.

6. The cationic binders of claim 3.

7. Use of the cationic binders of claim 4 in combination with crosslinking components in cathodic elec-trodeposition coatings.

8. Use of the cationic binders of claim 5 in combination with crosslinking components in cathodic elec-trodeposition coatings.

9. Use of the cationic binders of claim 6 in combination with crosslinking components in cathodic elec-trodeposition coatings.