DE3614435A1 - Process for the preparation of cationic epoxy resin esters - Google Patents

Abstract

The invention relates to a process for the preparation of cationic paint binders which crosslink on their own or otherwise, preferably for the formulation of cathodic electrodeposition coatings (paints, enamels, lacquers, varnishes), based on epoxy resin ester/amine adducts. The products contain substituted urea configurations bonded to the epoxy resin/amine adduct via ester bonds. The products have, in particular, advantages with respect to the mechanical properties and the adhesion properties of the coatings produced therefrom.

Description

Process for the production of cationic epoxy resin esters

Process for making cationic epoxy resin esters The invention relates to a process for the production of externally and self-crosslinking lacquer binders based on cationic epoxy ester resins. The products exhibit as characteristic Groups substituted urea structures, through which the adhesion properties of the crosslinked films both in terms of the substrate and in relation to one Follow-up layer is improved. In addition, by selecting the substituents, the minimum film formation temperature and the elasticity of the films in cheaper and easier Way to be influenced.

The chain extension of epoxy resins to influence the adhesive strength and the elasticity of the crosslinked films without affecting the corrosion resistance, is used in the manufacture of cationic resins, especially binders for cathodic electrocoating (KETL), tried in a variety of ways.

Attempts to extend the chain with diphenols, which lead to a Molecular elongation in low molecular weight epoxy resins are among others in US-PSS 4,339,368, 4,339,369 or DE-OSS 23 39 398 or 25 31 960. In this way, however, apart from an increase in the size of the molecule, there is no significant influence the adhesion property or the film formation temperature.

By partial esterification with long-chain monocarboxylic acids and / or Di- b polycarboxylic acids, e.g.

B. maleinized oils or maleinized polybutadienes, acidic alkyd resins or copolymers should according to the DE-AS 19 30 949 both the adhesive strength and elasticity can be improved.

According to US Pat. No. 4,104,147 or US Pat. No. 4,148,772, chain elongation takes place in the case of cationically modified epoxy resins by reacting with polyols with at least 2 primary hydroxyl groups, which increases the breakdown voltage and the film-forming temperature or the elasticity of the films can be improved.

Recently it has been shown that these modifications are no longer sufficient to meet the increased demands, especially in the automotive industry sufficient to satisfy.

According to more recent findings, the adhesive strength can be more cathodically applied Films are improved if the cationic binders used are amide structures exhibit. However, the type of installation is essential because, for example Aminoamide compounds from maleinized fatty acids and polyamines, as described in U.S. Patent 4,274,989 or U.S. Patent 4,036,795 are not related Show improvements.

Another possibility of incorporating amide and / or urea groups is described in the recently published EP-A2-0 137 459, with a chain extension in the case of epoxy resins by diamines, which have the groups mentioned. The basic groups responsible for the cationic character of the binders are introduced through additional amine additions.

In an application that does not belong to the state of the art (AT 713/84 / 2450) carboxamide structures are introduced via special secondary amines, which at the same time proportionately or entirely to the molecule for the water dilutability give the necessary cationic character.

It has now been found that cationic binders based on Bisphenol or phenol novolak epoxy resins are advantageous in terms of adhesion and Elasticity properties, but also with regard to the film formation temperature can be modified if substituted urea groups are used as the modifying element load-bearing molecular building blocks are used, which are esterified with part of the Epoxy groups of the epoxy resins are incorporated into the molecule.

The invention accordingly relates to a process for the production of externally crosslinking or self-crosslinking cationic lacquer binders based on epoxy ester resins containing substituted urea groups, which is characterized in that 1 epoxy val of an epoxy resin or a mixture of several epoxy resins, preferably based on diphenols, with an epoxy equivalent from 160 to 2000 with 0.1 to 0.6 eq of a reaction product of at least 1 mole, preferably 2 moles, of at least one acid anhydride group-containing di- or polycarboxylic acid and a hydroxyl-containing substituted urea compound obtained by reaction of secondary alkanolamines and diisocyanates general formula where R represents an aliphatic, cycloaliphatic or aromatic hydrocarbon radical and the radicals R1, the radicals of the secondary amines having optionally further substituted urea configurations R1 - N - CO - NH - R - NH - CO - N - R1, and with 0.4 to 0 , 9 val of one or more primary and / or secondary amines and / or optionally further carboxylic acids in a known manner to an epoxy resin ester-amine adduct which has an amine number of at least 40 mg KOH / g.

As already mentioned, the products produced according to the invention have improved adhesion properties. Especially can with these materials a particularly critical problem for the automotive industry, namely adhesion of underbody protection compounds, sealing compounds and the like on polyvinyl chloride or other polymer-based coatings are dissolved.

Usually these show z. T. directly onto the K-ETL primer applied layers only have moderate adhesion to the primer. Through the through the process according to the invention is achieved at the same time as the chain extension The elasticity of the stoved films is improved. Through the possible modifications it is also possible to influence the minimum film-forming temperature, as a result of which the flow during film formation can be improved even with thicker layers can.

The epoxy resins as used in accordance with the process according to the invention are described in large numbers in the literature and in Pirmenschriften. The books by A.M. PAQUIN "epoxy compounds and Epoxy resins ", Springer-Verlag, 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. Preferably the diglycidyl ethers of diphenols, especially the corresponding compounds of bisphenol A are used.

The products prepared according to the invention contain substituted urea compounds of the general formula which carry hydroxyl groups as an essential component where R and R1 have the meaning given in the main claim. These compounds are reacted with dicarboxylic or polycarboxylic acids which have at least one anhydride group to form half-esters and are linked to the epoxy resins via the carboxyl groups that are formed or are also present.

If these reaction products have two or more carboxyl groups, there is a chain extension between two epoxy resin molecules, which in particular a flexibilization of the entire molecule is brought about; when using monocarboxylic acids the molecule is lengthened at the end. This is also an effective way Influence of the film formation temperature is possible.

The compounds of the formula (I) are made by reacting diisocyanates obtained with secondary alkanol mono- and / or diamines. By the preferred reaction the Isocyanate groups with the amino hydrogen become the desired ones Urea groups obtained.

Diethanolamine and its homologues can be used as secondary alkanolamines as well as reaction products of primary monoamines or primary alkanolamines with Monoepoxides or reaction products of primary alkanolamines with acrylates are used will.

Secondary diamines, which are suitable for the implementation, are for example by reacting an N-alkoxy-alkylenediamine (N-alkylaminoalkanolamine) z.

B. N-ethoxyethylenediamine and its homologues with a monoepoxide compound according to the scheme HO - X - NH - Y - NH - CH2 - CH (OH) - Z where X, Y and Z are identical or different alkyl or

Represent alkylene radicals. As monoepoxide compounds are preferably monoglycidyl compounds of fatty acids, especially the glycidyl ester the VERSATIC acid, a saturated C9 - C 11 monocarboxylic acid, whose carboxyl group predominantly bonded to a tertiary carbon atom is used.

Other monoepoxide compounds are, for example, styrene oxide and dodecene oxide or alkyl or aryl glycidyl ethers, such as 2-ethylhexyl glycidyl ether or phenyl glycidyl ether.

Other secondary diamines can be obtained by reacting primary diamines, such as the alkylenediamines and monoepoxide compounds at a molar ratio of 1 : 2 or primary-secondary diamines, such as N-alkylalkylene diamines or cyclic triamines, such as 1- (2-aminoethyl) piperazine with, based on the primary Amino groups, equimolar amounts of monoepoxide are obtained.

Likewise, reaction products from 2 moles of a primary monoalkylamine, z. B. butylamine or 2-ethylhexylamine with a diepoxide compound, preferably a diglycidyl ether of a polyalkylene glycol can be used. Another representation method consists in the reaction of one mole of a diacrylate with 2 moles of a primary alkanol monoamine, such as monoethanolamine or 2-amino-2-ethyl-propanediol-13.

Of course, secondary diamines other than compounds described here are used. The ways of making such Connections are not claimed in this application.

The urea derivatives used according to the invention are obtained by reaction with a diisocyanate: By changing the molar ratios between the secondary diamine and the diisocyanate, compounds with more than one structural unit being constructed.

Products of this type can be used, for example, through the formula image where n can be 1 to 4, can be represented. Compounds of this type in which n is either 1 or 2 are preferred.

Aliphatic, cycloaliphatic or aromatic diisocyanates can be used Diisocyanates are used.

The individual representatives of this class of compounds can refer to the relevant Literature. The commercial products such as Tolylene diisocyanate, tetramethylene or hexamethylene or 2,2,4-trimethylhexamethylene diisocyanate, Isophorone diisocyanate and the like can also be used aliphatic diols with diisocyanates, e.g.

B. from 1,6-hexanediol and toluene diisocyanate, which have two free isocyanate groups have, are used. The implementation of the diisocyanates with the disecondary 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 the solvent are in the reaction vessel submitted and the diisocyanate at 30 to 500C was added slowly and evenly. the Reaction is usually with the end the addition is complete, d. H. all isocyanate groups have reacted.

The urea derivatives bearing hydroxyl groups obtained in this way (formula I) to introduce the necessary for the implementation with the epoxy resins Carboxyl groups with di- or polycarboxylic acids containing at least one anhydride group have implemented with half-ester formation.

The reaction products have 1 to 5 carboxyl groups. Preferred become compounds with 2 carboxyl groups. With a higher carboxyl functionality is the resulting risk of gelation when reacting with the epoxy resins to be observed.

Dicarboxylic acid anhydrides are preferably used as di- or polycarboxylic acid anhydrides, such as the anhydrides of o-phthalic acid, tetra- or hexahydrophthalic acid or the Endomethylenetetrahydrophthalic acid used.

Other acid anhydrides are the anhydrides of aliphatic dicarboxylic acids such as succinic anhydride or maleic anhydride or tricarboxylic acid anhydrides, such as trimellitic anhydride or dianhydrides, such as pyromellitic acid.

The implementation of the hydroxyl group-bearing urea derivatives with the carboxylic anhydrides takes place in the presence of inert solvents at 90 to 1200C.

The reaction of the carboxyl compounds obtained in this way with the epoxy resins takes place at 90 to 15,000 up to an acid number of practical 0.

Per epoxy val of the epoxy resin 0.1 to 0.6 val, based on the carboxyl groups of the component are used. Preferably, each Val is epoxy resin 0.1 to 0.4 eq carboxyl compound is used.

The remaining epoxy groups are at least as far with primary or secondary amines implemented, that the reaction product a Has amine number of at least 40 mg KOH / g. As a practically epoxide group-free End product is sought, provided that the calculation A = Val epoxy groups - Val carboxyl groups - Val amino functions for A give a value above 0, the rest Epoxy functions before the amine reaction z. B. defunctionalized with monocarboxylic acids.

As primary and secondary amines, which lead to the introduction of the cationic Serving groups, alkanolamines such as diethanolamine, diisopropanolamine, Methylethanolamine or primary amines such as dimethylaminopropylamine or diethylaminopropylamine used.

The binders produced according to the invention are according to partial Neutralization of the basic groups - can be diluted with water and form after Dilute stable clear to opaque solutions. You will be using it prior to processing Crosslinking components and, if appropriate, pigments, fillers, catalysts and other paint additives. The manufacture of such water-thinnable Lacquers are known to those skilled in the art and must, like the processing technologies, cannot be described. The preventive application method for the paints on the basis the binder produced according to the invention is the electrodeposition coating, wherein the products deposited on the cathode due to their cationic character will.

The hardening of the products can be externally cross-linked both by transesterification with the help of malonic acid oligoesters and similar components, as well as blocked Polyisocyanates or amino resins take place. Self-crosslinking products can be used in well-known Way by incorporating semi-blocked diisocyanates or one sufficient Number of polymerizable groups can be achieved. Of course, too Combinations of different networking systems possible. The corresponding systems are known from the literature.

The following examples serve to explain the invention in more detail, without limiting their scope.

All data in parts or percentages relate unless nothing otherwise stated, based on weight units.

The following abbreviations are used in the examples: AEOLA Aminoethylethanolamine BAC butyl acrylate CE technical mixture of glycidyl esters of 1,1-Diemtyh- (c7-Cg) -alkanecarboxylic acids DEAPA Diethylaminopropylamine DIPA Diisopropanolamine DGME diethylene glycol dimethyl ether DMAPA dimethylaminopropylamine DODOX dodecene oxide DOLA Diethanolamine DPA Dipropanolamine EHA 2-Ethylhexylamine EPH I epoxy resin Based on polypropylene glycol 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 HHPA hexahydrophthalic anhydride HMDA hexamethylene diamine IPDI isophorone diisocyanate MIPA Monoisopropanolamine MIBK methyl isobutyl ketone MEOLA N-methylethanolamine OCTO octene oxide PA phthalic anhydride TDI tolylene diisocyanate TEX 2,2,4-trimethylpentane-1,3-diol monoisobutyrate (TEXANOL) THPA tetrahydrophthalic anhydride TMDI 2,2,4-trimethylhexamethylene diisocyanate TPGDA tripropylene glycol diacrylate (A) Production of the urea groups Carboxyl compounds Table 1 shows the compositions and the reaction conditions for the preparation of the carboxyl compounds containing urea groups. The reaction takes place in a with stirrer, adequate cooling, temperature display and addition vessels equipped reaction vessel carried out. In one first stage under the conditions specified in Table 1 from the primary Amines modified secondary amines produced, which then after addition the other secondary amines are reacted with the isocyanate.

When the diisocyanate reacts with the amines, the amines together with the intended solvent placed in the reaction vessel and the diisocyanate with cooling within 30 to 60 minutes (depending on the cooling capacity) at the specified Temperature added.

In the last columns of this table is the molar ratio between the diisocyanate and the di- or monoamine and the resulting OH functionality of the intermediate products (HK).

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

(B) Production of the binders according to the invention (Examples 1 to 6) The diepoxides are mixed in a reaction vessel as described under (A) the carboxyl compounds at 90 to 1200C up to one corresponding to the half-ester Acid number implemented. (A possible defunctionalization of further epoxy groups with other monocarboxylic acids can be carried out simultaneously or in a separate process stage take place before the amine reaction.) The details are summarized in Table 3.

Then the amines provided in accordance with Table 3 are added and the reaction was carried out at 75 to max. 85 "C to an epoxide value of 0.

(C) Testing of the Binders Produced According to the Invention The binders according to Example 1 to 6 were with the hardener component in the table specified in Tab Solids ratio bpi 600C mixed homogeneously and a pigmented one from this mixture Lacquer made. A colored paste is made according to the following recipe 25th Tle binder-hardener mixture (100 k) 0.25 tle carbon black 3 tle basic lead silicate pigment 36.75 parts of titanium dioxide produced on a suitable friction unit, which according to the homogenization with 75 parts (solid resin) of the binder mixture each time will.

The following products were used as crosslinking components: Hardener component X: transesterification hardener based on malonic ester according to AT-PS 372 099, e.g. B. accordingly "Component B 2".

Hardener component Y: transesterification hardener based on modified Malonic esters according to AT-PS 379.602 (A 2531/83), e.g. B. according to Example 1 hardener component Z: Transesterification hardener based on oligomeric β-hydroxyesters according to EP-B1-00 12 463, e.g. B. according to Example II (b).

The paints were neutralized and diluted to the specified Solids content under conditions which a dry film thickness of 20 t 2 pm result, deposited cathodically on zinc-phosphated steel sheet and at the specified Baked in temperature for 30 minutes. In all cases, the salt spray test is used according to ASTM B-117-64, an attack at the cross-cut after a test duration of 700 hours of less than 2 mm was found. In the humidity cabinet test (100% relative humidity at 50 ° C) the coatings are in perfect condition after 500 hours.

For testing the adhesive strength of PVC materials on the cathodic The lacquer deposited became the PVC layer in the form of a strip 2 mm thick and 1 cm wide 30 minutes after the K-ETL primer has been baked in and hardened for 7 minutes at 140-C (object temperature). The liability test was carried out 1 hour after baking.

The peelability of the PVC coating is assessed (grade 5 = easily peelable, grade 1 = not peelable, coating breaks without peeling from the subsoil).

A commercially available underbody protection (Stankiewicz 2252 of the Pa. Stankiewicz GmbH, Celle, Germany) and one in the automotive industry Seam sealing compound used (Dekalin 9003 from Pa. Dekalin, Deutsche Kleiebe-Werke, Hanau, FRG).

Assessment of the results, underbody protection, seam sealant grade Lacquer no. Lacquer no.

1 1, 3, 4, 7, 10 1, 2, 3, 7 2 2, 5, 6, 8, 9 4, 5, 6, 9 3 8, 10 4 - 5 comparative varnish A, comparative varnish A, C 5 comparative varnish B, C comparative varnish B as Comparative varnish A was a back produced in the same way on the basis of a Combination of 30 parts (solid resin) of a binder according to Example 29 of US Pat 4,174,332 and 70 parts (solid resin) according to Example 8 of EP-B1-00 12 463 are used. In the case of comparative varnish B, the ratio of the two components was changed to 50:50. Comparative lacquer C was based on a binder combination according to Example 4 EP-B1-00 49 369. None of these binders has substituted in its structure Urea groups.

Table 1: Manufacture of intermediate products (HK) Preparation of the modified secondary amines A amine monoepoxide diepoxide (di) acrylate reaction Tle (Mol) Tle (Mol) Tle (Mol) Tle (Mol) conditions resulting Amine 1 --- --- -- -- --- 2 146 MIPA (2.0) --- - 252 BAC (2.0) addition: 1h / 30 ° C + 1 h / 75 ° C Monoamine 3 114 HMDA (1.0) 200 OCTO (2.0) - - 2 h / 100 ° C Diamine 4 292 BA (4.0) - 800 EPH I (2.0) - 3 h / 75 ° C Diamine 5 292 MIPA (4.0) 500 CE (2.0) - 296 TPGDA (1.0) addition: 1h / 45 ° C + 2 h / 100 ° C Mono - + diamine 6 208 AEOLA (2.0) 368 DODOX (2.0) - - 2h / 100 ° C Diamine Continuation on next page Continuation of Table 1 Further secondary isocyanate reaction Monoamines Amine. Diisocyanate Solvent max. To- Molver- *) OH func- A Tle (mol) Tle (mol) solid-state input temp. relationship salary% 1 210 DOLA (2.0) 210 TMDI (1.0) 70 DGME 40 ° C 1: 0: 2 4 HK 1 2 - 222 IPDI (1.0) 75 MIBK 45 ° C 1: 0: 2 2 HC 2 3 258 DIPA (2.0) 348 TDI (2.0) 75 MIBK 35 ° C 2: 1: 2 6 HK 3 4 258 DPA (2.0) 630 TMDI (3.0) 70 DGME 35 ° C 3: 2: 2 8 HK 4 5 - 420 TMDI (2.0) 80 MIBK 40 ° C 2: 1: 2 6 HK 5 6 146 MEOLA (2.0) 666 IPDI (3.0) 70 MIBK 45 ° C 3: 2: 2 6 HK 6 *) Diisocyanate: diamine: monoamine Table 2 Carboxyl group-bearing urea derivatives (CS) according to formula (I) CS TEILE HK Dicarboxylic acid ratio partial dissolution COOH equi- reaction (Solid resin) anhydride OH / anhyd% weight temperature Tle tle (mol) three solid content 1 420 HK 1 304 THPA (2.0) 4: 2 70 DGME 362 95 2 620 HK 2 237 PA (1.6) 2: 1.6 70 MIBK 536 100 3 920 HK 3 385 HHPA (2.5) 6: 2.5 75 MIBK 522 110 4 1980 HK 4 304 THPA (2.0) 8: 2 70 DGME 1142 100 5 1508 HK 5 456 THPA (3.0) 6: 3 70 MIBK 655 110 6 1388 HK 6 308 HHPA (2.0) 6: 2 70 MIBK 848 110 Table 3 Preparation of the binders With- EPOXY RESIN CS sec. AMINE PRIM. AMINE SOLVENTS Solid CHARACTERISTICS game Tle (VAL) Tle (VAL) Tle (VAL) Tle total body amine number / solid) content mg KOH / G 1 1425 EPH III (3.0) 290 CS (0.8) 77 DIPA (0.6) 104 DEAPA (1.6) 65 65 77 EHA (1.2) 2 494 EPH II (2.6) 375 CS 2 (0.7) - 36 DMAPA (0.7) 602 MIBK 62 74 190 EPH II (1.0) 3 475 EPH III (1.0) 313 CS 3 (0.6) - 91 DEAPA (1.4) 576 MIBK 65 73 4 950 EPH III (2.0) 571 CS 4 (0.5) - 77 DMAPA (1.5) 899 DGME 64 53 200 EPH I (0.5) 5 197 CS 5 (0.3) 126 DOLA (1.2) 65 DEAPA (1.0) 659 MIBK 70 80 950 EPH III (2.0) 6 418 EPH II (2.2) 339 CS 6 (0.4) 73 MEOLA (1.0) 52 DEAPA (8.0) 415 MIBK 68 114 Table 4: Composition of the test lacquers (all weight data for resins refer to solid resin) LACQUER No. 1 2 3 4 5 4 6 7 8 7 9 10 binder Example 1 80 75 Example 2 75 70 Example 3 80 70 Example 4 85 Example 5 80 Example 6 70 75 Hardener component X 20 30 25 20 20 Y 25 20 15 30 Z 30 Neutralizing agent (mmol / 100 g solids.) Acetic acid 40 40 40 45 Formic acid 40 35 40 45 40 40 Auxiliary solvents 35 TEX 50 TEX 38 TEX deion. Water 692 689 560 750 612 589 590 701 702 662 Solids content of paint (%) 16 16 18 15 20 18 18 16 16 16 Stoving temperature ° C 180 170 170 170 180 160 170 180 160 160

Claims (9)

Claims: 1. Process for the production of externally crosslinking or self-crosslinking cationic lacquer binders based on epoxy ester resins containing substituted urea groups, characterized in that 1 epoxy val of an epoxy resin or a mixture of several epoxy resins, preferably based on diphenols, with an epoxy equivalent of 160 to 2000 with 0.1 to 0.6 eq of a reaction product of at least 1 mole, preferably 2 moles, of a di- or polycarboxylic acid containing at least one acid anhydride group and a substituted urea compound of the general formula containing hydroxyl groups and obtained by reaction of secondary alkanolamines and diisocyanates where R represents an aliphatic, cycloaliphatic or aromatic hydrocarbon radical and the radicals R1, the radicals of the secondary amines having optionally further substituted urea configurations R1 - N - CO - NH - R - NH - CO - N - R1, and with 0.4 to 0 , 9 val of one or more primary and / or secondary amines and / or optionally further carboxylic acids in a known manner to an epoxy resin ester-amine adduct which has an amine number of at least 40 mg KOH / g. 2. The method according to claim 4, characterized in that the carboxylic acid component from reaction products of diisocyanates with alkanolamines by half-ester formation with dicarboxylic acid anhydrides. 3. The method according to claim 2, characterized in that as a secondary Dialkanolamines by reacting a diamine which has at least one primary amino group having, compounds obtained with a monoepoxide compound can be used. 4. The method according to claim 2, characterized in that as a secondary Dialkanolamines by reacting a diacrylate with a primary alkanolamine obtained compounds are used. 5. The method according to claims 1 to 4, characterized in that that compounds of the formula (I) which in the radicals R1 are 1 to 4, preferably 1 to 2 further substituted urea groups by changing the molar ratios between diisocyanate and secondary diamine. 6. The method according to claims 1 to 5, characterized in that that defunctionalization of the epoxy resins by other carboxylic acids before Reaction with the amines takes place. 7. Process for the production of self-crosslinking binders the products produced according to claims 1 to 6, characterized in that one part of the hydroxyl groups of the products with half-blocked diisocyanates and / or polymerizable double bonds having monoisocyanates. 8. Use of the binders prepared according to claims 1 to 7, optionally in combination with crosslinking components to formulate water-soluble ones Lacquers. 9. Use of the binders prepared according to claims 1 to 7, optionally in combination with crosslinking components for the formulation of cathodic separable electrodeposition paints.