DE3614435C2 - - Google Patents

Description

The invention relates to a method for manufacturing of externally cross-linking or self-cross-linking cationic paint binders based on having substituted urea groups Epoxy resin ester amine adducts. The products show as characteristic groups of substituted urea structures through which the adhesion properties the cross-linked films both with regard to the substrate, as well as compared to a subsequent shift. Furthermore, by selecting the substituents, the minimum Film formation temperature and the elasticity of the films in be influenced more cheaply and easily.

The chain extension of cationic epoxy resins, as used in particular as a binder for the cathodic Electrocoating (KETL) was used already tried in different ways.

Attempts to extend the chain with diphenols, which to a molecular extension in low molecular weight Lead epoxy resins are, inter alia, in US Pat. No. 4,339,368, 43 39 369 or DE-OS 23 39 398 or 25 31 960 described. This way, however, is beyond molecular enlargement no significant influence on the Adhesion properties or the film formation temperature to reach.

Through partial esterification with long-chain monocarboxylic acids and / or di- or polycarboxylic acids, e.g. B. maleinized Oils or maleinized polybutadienes, acidic alkyd resins or copolymers according to DE-AS 19 30 949 both the adhesive strength as well as the elasticity can be improved.  

According to US-PS 41 04 147 or US-PS 41 48 772 chain extension occurs with cationic modified epoxy resins by reaction with polyols with at least 2 primary hydroxyl groups, whereby the breaking voltage and the film formation temperature or the elasticity of the films can be improved can.

However, it has been shown that these modifications are no longer are sufficient to meet the increased demands in particular Satisfying the automotive industry sufficiently.

According to recent knowledge, the adhesive strength cathodic films are improved, if the cationic binders used amide structures exhibit. However, the type of installation is essential Significance because, for example, aminoamide compounds maleinized fatty acids and polyamines, as in the US-PS 42 74 989 or US-PS 40 36 795 described will not show any improvements in this regard.

Another way of installing amide and / or Urea groups are described in EP-A2 01 37 459, chain extension in epoxy resins Diamines, which have the groups mentioned, takes place. The for the cationic character of the binder responsible basic groups are identified by additional Amine additions introduced.

According to the AT-PS not belonging to the state of the art 3 79 406 carboxylic acid amide structures on special secondary amines are introduced, which are proportionate at the same time or entirely the molecule for water dilutability give necessary cationic character.  

It has now been found that cationic paint binders based on substituted urea groups epoxy resin ester amine adducts, such as bisphenol or phenolic novolak epoxy resins, favorably regarding the adhesion and elasticity properties, but also with regard to the film formation temperature can modify if one as a modifying element substituted molecular building blocks bearing urea groups uses, which by esterification with part of the Epoxy groups of the epoxy resins built into the molecule will.

The inventive method for the production of externally cross-linking or self-cross-linking cationic Paint binders based on substituted Epoxy resin ester amine adducts containing urea groups is characterized in that 1 epoxyval one Epoxy resin or a mixture of several epoxy resins with an epoxy equivalent mixture from 160 to 2000 at 90 to 150 ° C up to an acid number of practically 0 with 0.1 to 0.6 val of a reaction product from at least 1 mole, preferably 2 moles of a di- or Polycarboxylic acid and one by reaction of at least 1 hydroxyl group-containing secondary mono- or di-amines and substituted urea compounds obtained from diisocyanates the general formula

where R is an aliphatic, cycloaliphatic or aromatic diisocyanate or one of these  Diisocyanates and an aliphatic diol obtained The underlying diisocyanate compound and the R₁, which may be the same or different, from the choice of secondary amine if a diamine was used, optionally by the reaction of Diisocyanates further substituted urea groups analogous to formula (1), and with 0.4 to 0.9 Val of one or more primary and / or secondary Amines and / or optionally further monocarboxylic acids, the structure of which is not that of compounds or Formula (1) obtained correspond in a known manner to an epoxy resin ester-amine adduct free of epoxy groups, which has an amine number of at least 40 mg KOH / g, implements, and that one for the production of self-crosslinking Binders optionally part of the hydroxyl groups of the products before protonation and / or addition of Water and / or isocyanate-reactive solvent semi-blocked diisocyanates and / or polymerizable Monoisocyanates having double bonds.

In particular, these materials can be used for Automotive industry particularly critical problem, namely the liability of underbody protection compounds, sealing compounds and the like on polyvinyl chloride or other polymers based coatings can be solved. Usually show this z. T. applied directly to the K-ETL primer Layers only have moderate adhesion to the primer. By the achieved by the inventive method Chain extension becomes elasticity at the same time of the branded films improved. By the possible Modifications are also influencing the minimum Film formation temperature possible, whereby the course of the Film formation also improved with higher layer thicknesses can be.  

The epoxy resins as they are according to the inventive method are used in the literature and in company publications described. Books are the standard works here by A. M. PAQUIN, Berlin (1958) and H. LEE and K. NEVILLE "Handbook of Epoxy Resins", Mc Graw-Hill Book Co. (1967) mentioned.

The epoxy resins suitable for the process according to the invention have an epoxy equivalent weight of 160 to 2000 on. The diglycidyl ethers of diphenols, in particular the corresponding compounds of bisphenol A used.

The essential building block contain the invention Products manufactured substituted hydroxyl groups Urea compounds of the general formula (1), the with di- or polycarboxylic acids, which have at least one Have anhydride group, implemented with half-ester formation and about the emerging or existing ones Carboxyl groups are linked to the epoxy resins.

Unless these reaction products have two or more carboxyl groups have a chain extension between two epoxy resin molecules, which in particular the entire molecule is made more flexible; when using monocarboxylic acids the molecule finally extended. This way is additional an effective influence on the film formation temperature possible.

The compounds of formula (1) are obtained by reaction obtained from diisocyanates with secondary and / or diamines. The preferred reaction of the isocyanate groups with  the desired urea groups are added to the amino hydrogen receive.

Diethanolamine and its can be used as secondary monoamines Homologues and reaction products of primary monoamines or primary alkanolamines with monoepoxides or Reaction products of primary alkanolamines with acrylates be used.

Secondary diamines, which are suitable for the implementation, are, for example, by reaction of an N-alkoxy-alkylene diamines (N-alkylaminoalkanolamines) e.g. B. N-ethoxyethylene diamine and its homologues with a monoepoxide compound the scheme

where X, Y and Z are the same or different alkyl or Represent alkylene residues, obtained. As monoepoxide compounds are preferably monoglycidyl compounds of Fatty acids, especially the glycidyl ester of VERSATIC® acid, a saturated C₉-C₁₁ monocarboxylic acid Carboxyl group mainly on a tertiary carbon atom is bound, used. Other monoepoxide compounds are, for example, styrene oxide, dodecene oxide or alkyl or arylglycidyl ether, such as the 2-ethylhexylglycidyl ether or phenylglycidyl ether.

Other secondary diamines can be reacted by primary diamines such as the alkylene diamines and monoepoxide compounds at a molar ratio of 1: 2 or primary-secondary diamines, such as N-alkylalkylenediamines  or cyclic triamines such as 1- (2-aminoethyl) piperazine with, based on the primary amino groups, equimolar amounts of monoepoxide can be obtained. Likewise, reaction products from 2 moles of one primary monoalkylamines, e.g. B. butylamine or 2-ethylhexylamine with a diepoxide compound, preferably a diglycidyl ether of a polyalkylene glycol, be used. Another display method exists in the reaction of one mole of a diacrylate with 2 moles a primary alkanol monoamine, such as monoethanolamine or 2-amino-2-ethyl-propanediol-1,3.

Of course, secondary diamines can also other than the compounds described here used will. The ways of making such connections are not claimed.

By reaction with a diisocyanate Urea derivatives used according to the invention receive:

By changing the molar ratios between the secondary Diamine and the diisocyanate can contain compounds with more than one Structural unit  

being constructed.

Products of this type can, for example, by the formula picture

where n is 1 to 4. Compounds of this type are preferred in which n is either 1 or 2.

Aliphatic, cycloaliphatic or aromatic diisocyanates can be used. The individual representatives of this connection class can can be found in the relevant literature. Preferably are the commercially available products, such as toluene diisocyanate, tetramethylene or hexamethylene or 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate u. Ä. used. Furthermore, reaction products from aliphatic diols with diisocyanates, e.g. B. from 1,6-hexanediol and tolylene diisocyanate, which have two free isocyanate groups used will. Implementation of the diisocyanates with the secondary ones Amines are preferably carried out in the presence of aprotic solvents such as diethylene glycol dimethyl ether or methyl isobutyl ketone. The amine (mixture) and submitted the solvent in the reaction vessel and the diisocyanate is uniformly slow at 30 to 50 ° C admitted. The reaction is usually over  the addition ended, d. H. all have isocyanate groups responds.

The urea derivatives bearing hydroxyl groups thus obtained (Formula I) will introduce the for the Implementation with the necessary epoxy resins carboxyl groups with di- or polycarboxylic acids, the at least one Have anhydride group, implemented with half-ester formation. The reaction products have 1 to 5 carboxyl groups on. Compounds with 2 carboxyl groups are preferred. With a higher carboxyl functionality that is this creates the risk of gelling during implementation with the epoxy resins.

Preferred di- or polycarboxylic anhydrides are Dicarboxylic anhydrides, such as the anhydrides o-phthalic acid, tetra- or hexahydrophthalic acid or endomethylene tetrahydrophthalic acid. Other acid anhydrides are the more aliphatic anhydrides Dicarboxylic acids such as succinic anhydride or maleic anhydride or tricarboxylic anhydrides, such as trimellitic anhydride or dianhydrides, such as pyromellitic acid.

The implementation of the hydroxyl-bearing urea derivatives with the carboxylic anhydrides takes place in Presence of inert solvents at 90 to 120 ° C.

The reaction of the carboxyl compounds obtained in this way with the epoxy resins at 90 up to 150 ° C up to an acid number of practically 0. For each epoxy val of the epoxy resin, 0.1 to 0.6 val, based on the carboxyl groups of the component, used. Epoxy resin is preferred per Val 0.1 to 0.4 val carboxyl compound used.

The remaining epoxy groups are at least implemented so far with primary or secondary amines,  until the reaction product has an amine number of at least 40 mg KOH / g. Because it is practically free of epoxy groups End product is aimed for, provided the calculation A = Val epoxy groups - Val carboxyl groups - Val amino functions for A a value above 0 results in the remaining epoxy functions before Amine conversion z. B. with monocarboxylic acids nalized.

As primary and secondary amines, which are to be introduced serving the cationic groups are preferred Alkanolamines, such as diethanolamine, diisopropanolamine, Methylethanolamine or primary amines such as dimethyl aminopropylamine or diethylaminopropylamine used.

The binders produced according to the invention are after partial neutralization of the basic groups dilutable with water and form after dilution stable clear to opaque solutions. You will before Processing with networking components as well as if necessary Pigments, fillers, catalysts and others Paint auxiliaries added. The production of such water-thinnable lacquers are known to the person skilled in the art and like the processing technologies, does not have to to be discribed. The preferred order method for the paints based on those produced according to the invention Binder is the electrocoating, whereby the Products due to their cationic character at the Cathode to be deposited.

The curing of the products can be both cross-linking by transesterification with the help of malonic acid oligoesters and similar components, as well as blocked by Polyisocyanates or amino resins are used. Self-networking Products can be obtained in a known manner Installation of semi-blocked diisocyanates or one  sufficient number of polymerizable groups be achieved. Combinations are of course also possible different networking systems possible. The corresponding systems are known from the literature.

The following examples are used for further explanation of the invention without restricting its scope. All details in parts or percentages relate to unless otherwise specified, by weight units.

The following abbreviations are used in the examples uses:

AEOLAAminoethylethanolamine BAn-Butylamine BACButylacrylat CEtechnical mixture of glycidyl esters
the 1,1-dimethyl- (C₇-C₉) -alkanecarboxylic acids DEAPADiethylaminopropylamin DIPADiisopropanolamin DGMEDiethylenglykoldimethylether DMAPADimethylaminopropylamin DODOXDodecenoxid DOLADiethanolamine DPADipropanolamin EHA2-Ethylhexylamin EPH IEpoxidglykol based on polypropylene
Molecular weight approx. 400 EPH II epoxy resin based on bisphenol A
Equivalent weight = 200 EPH III epoxy resin based on bisphenol A
Equivalent weight = 475 HHPAHexahydrophthalsäureanhydrid HMDAHexamethylendiamin IPDIIsophorondiisocyanat MIPAMonoisopropanolamin MIBKMethylisobutylketon MEOLAN-methylethanolamine OCTOOctenoxid PAPhthalsäureanhydrid TDIToluylendiisocyanat TEX2,2,4-trimethylpentane-1,3-diol monoisobutyrate (TEXANOL) THPATetrahydrophthalsäureanhydrid TMDI2,2,4-trimethylhexamethylene TPGDATripropylenglykoldiacrylat

(A) Preparation of the urea groups Carboxyl compounds

In Table 1 the compositions are as well the reaction conditions for manufacture of carboxyl compounds containing urea groups summarized. The reaction is in one with Agitator, sufficient cooling, temperature display and addition vessels equipped reaction vessels carried out. In a first stage under the conditions given in Table 1 secondary ones modified from the primary amines Amines produced, which then after addition the other secondary amines with the isocyanate be implemented.

In the reaction of the diisocyanate with the amines the amines along with the intended Solvent submitted in the reaction vessel and that Diisocyanate with cooling within 30 to 60 Minutes (depending on cooling capacity) at the specified Temperature added.  

That is in the last columns of this table molar ratio between the diisocyanate and the Diamine or monoamine and the resulting OH functionality of intermediate products (HK) specified.

Table 2 contains information on the further implementation of the intermediate products (HK) with the Dicarboxylic acid anhydrides.

(B) Preparation of the binders by the process according to the invention (Examples 1 to 6)

In a reaction vessel as described under (A) become the diepoxides with the carboxyl compounds at 90 to 120 ° C up to one of the half esters corresponding acid number implemented. (A possible Defunctionalization of other epoxy groups with other monocarboxylic acids at the same time or in a separate process stage the amine reaction.) The details are summarized in Table 3.

Then, according to Table 3 provided amines added and the reaction 75 to max. 85 ° C up to an epoxy value of 0 guided.

(C) Testing the bindemem produced according to the invention tel

The binders according to Examples 1 to 6 were used the hardener component in that specified in Table 4 Solid ratio mixed homogeneously at 60 ° C and from this mixture a pigmented lacquer produced. Doing so corresponds to the following Recipe a color paste  

25 parts of binder and hardener (100%) 0.25 Tle color black 3 Tlebasic lead silicate pigment 36.75 parts of titanium dioxide

produced on a suitable friction unit, which after homogenization with 75 parts each (solid resin) the binder mixture is completed.

The following products were used as networking components used:

Hardener component X: transesterification hardener based on malonic ester according to AT-PS 3 72 099, e.g. B. corresponding to "component B 2".
Hardener component Y: transesterification hardener based on modified malonic esters according to AT-PS 3 79 602 (A 2531/83), e.g. B. according to Example 1.
Hardener component Z: transesterification hardener based on oligomeric β -hydroxy esters according to EP-B 1-00 12 463, e.g. B. according to Example II (b).

The paints were on after neutralization and dilution the stated solids content under conditions, which give a dry film thickness of 20 ± 2 µm, Cathodically deposited on zinc-phosphated steel sheet and at the specified baking temperature 30 Minutes burned in. In all cases, the salt spray test according to ASTM B-117-64 after a test period of An attack on the cross cut of less than 700 hours 2 mm determined. In the wet cabinet test (100% relative humidity at 50 ° C) are the coatings after 500 hours in perfect condition.  

For testing the adhesive strength of PVC materials on the cathodically deposited varnish PVC layer in the form of a strip 2 mm thick and 1 cm wide 30 minutes after baking the K-ETL primer applied and 7 minutes at 140 ° C (Object temperature) hardened. Checking liability was done 1 hour after baking.

The peelability of the PVC coating is assessed (Note 5 = easily removable, Note 1 = not removable, coating breaks without detachment from the underground).

A commercial underbody protection was used as PVC materials (Stankiewicz 2252 from Stankiewicz GmbH, Celle, FRG) and one in the automotive industry used seam sealing compound (Dekalin 9003 der Dekalin, German Adhesive Works, Hanau, Germany) used.

Assessment of results

As comparative varnish A, a varnish produced in the same way and based on a combination of 30 parts (solid resin) of a binder according to Example 29 of US Pat. No. 4,174,332 and 70 parts (solid resin) according to Example 8 of EP-B1-00 12 463 was used . In comparative paint B, the ratio of the two components was changed to 50:50. Comparative paint C was based on a binder combination according to Example 4 of EP-B1-00 49 369. None of these binders has substituted urea groups in its structure.

Table 1

Table 2

Carboxyl group-bearing urea derivatives (CS) according to formula (I)

Claims (9)

1. A process for the preparation of externally crosslinking or self-crosslinking cationic paint binders based on epoxy resin ester amine adducts containing substituted urea groups, characterized in that 1 epoxyvalue of an epoxy resin or a mixture of several epoxy resins with an epoxy equivalent weight of 160 to 2000, at 90 to 150 ° C, C up to an acid number of practically 0 with 0.1 to 0.6 val of a reaction product of at least 1 mol of a di- or polycarboxylic anhydride and a substituted urea compound obtained by reaction of at least 1 hydroxyl-containing secondary mono- or diamines and diisocyanates the general formula where R is an aliphatic, cycloaliphatic or aromatic diisocyanate or that of a residue obtained from these diisocyanates and an aliphatic diol, and the radical R₁, which may be the same or different, result from the choice of the secondary amine and, if a diamine is used was, optionally by reaction of diisocyanates, may contain further substituted urea groups analogous to formula (1), and with 0.4 to 0.9 val of one or more primary and / or secondary amines and / or optionally further monocarboxylic acids which do not have the same structure obtained from compounds or formula (1) correspond, in a known manner, to an epoxy group-free amine ester amine adduct which has an amine number of at least 40 mg KOH / g, and that, if appropriate, part of the hydroxyl groups of the products are prepared for the preparation of self-crosslinking binders a protonation u nd / or addition of water and / or isocyanate-reactive solvents with half-blocked diisocyanates and / or polymerizable double bonds having monoisocyanates. 2. The method according to claim 1, characterized in that that as an epoxy resin on the Base of diglycidyl ethers of diphenols is used. 3. The method according to claim 1 to 2, characterized characterized in that as a carboxylic acid component a reaction product according to formula (1) is used by using half-ester formation Obtained dicarboxylic anhydrides at 90 to 120 ° C. has been. 4. The method according to claim 3, characterized characterized that as secondary Dialkanolamines are used by those Implementation of a diamine that is at least one primary Has amino group with a monoepoxide compound have been obtained.   5. The method according to claim 3, characterized characterized that as secondary Dialkanolamines used are those that by reacting a diacrylate with a primary alkanolmin have been obtained. 6. The method according to claims 1 to 5, characterized characterized that connections of the formula (1), which in the radicals R₁ 1 to 4, preferably 1 to 2 further substituted urea groups have by changing the molar ratios obtained between diisocyanate and secondary diamine have been. 7. The method according to claim 1 to 2, characterized characterized that a partial Defunctionalization of the epoxy resins to achieve this of an end product free of epoxy groups carboxylic acids other than that by reacting Acid anhydrides with compounds of the formula (1) obtained, before implementation with the primary and / or secondary amines. 8. Use of the produced according to claims 1 to 8 Binder, optionally in combination with Crosslinking components, for the formulation of water-soluble Paints. 9. Use of the produced according to claims 1 to 8 Binder, optionally in combination with Crosslinking components, for the formulation of cathodic separable electrodeposition paints.