DE3246812A1 - CURABLE, CATIONIC MODIFICATION PRODUCTS OF EPOXY RESINS, METHOD FOR THE PRODUCTION THEREOF AND THEIR USE - Google Patents

Abstract

Hardenable and cationic modifying agents for epoxy resins, characterized by a certain content of beta -hydroxyalkylcarbamide esters, of which the amide group originates from a polyamine with at least two primary and/or secondary amino groups, and optionally tertiary amino groups, of which two nitrogen bonds are occupied by hydrocarbon rests, the resins being as such or in an acid protonized form, dissolved in water or in an organo aqueous system and containing optionally conventional additives, at least 70 % of the epoxy groups are caused to react; the production process as well as the utilization of said agents are also disclosed.

Description

Curable, cationic modification products of epoxy

Resins, process for their preparation and their use The invention refers to curable, cationic modification products of epoxy resins, as the crosslinking principle »-hydroxyalkyl carbamide esters and optionally additionally contain tertiary amine groups, made water-soluble and also with the cataphoretic Dip painting can be applied.

It is known to combine epoxy resins with amines, carboxylic acids, melamine resins, To crosslink phenolic resins, urea resins and others. Cationic epoxy derivatives usually contain amine groups which, after protonation, are converted into allow an aqueous phase. Such resins can be made from the aqueous solutions cataphoretic dip painting by applying direct current to electrical conductive substrates are deposited. They cannot be networked Amines and free carboxylic acids, but certain polyfunctional carboxylic acid esters be applied. Melamine resins, phenolic resins and urea resins can also be used, but are usually used as precondensates. This preferred embodiment Although it eliminates the disadvantages of paint technology, it leads to high molecular masses and thus an increase in viscosity that is often undesirable.

Self-crosslinking epoxy resin derivatives are also produced by that polyisocyanates to the hydroxyl groups or reactive amine groups of the epoxy resin modification product partially added and then capped. Serve as a capping agent usually alcohols or substances with amine groups. It is also possible to be amine-free React epoxy resins or their derivatives with polyisocyanates and / or cationic Groups that also serve as capping agents on isocyanate groups, e.g. B. the leftover, add up.

B; This technically carried out process has disadvantages because of the poor handling of the isocyanates. These connections are strong toxic and sensitive to compounds containing water and hydroxyl groups.

The isocyanate groups also tend in the presence of strong bases for polymerization. The main disadvantage of the resins produced in this way, however, lies in the high decapping temperature; As a rule, wounds under practical conditions are common from 1700C, but usually only possible at even higher temperatures. To at the addition of the isocyanate to the epoxy resin to avoid unwanted molecular enlargements, one uses such diisocyanates as a rule, z. B.

oluylene diisocyanate, the isocyanate groups of which have different reactivities exhibit. The more reactive isocyanate group reacts with the epoxy resin, the more sluggish remains, so that molecular enlargements are avoided in this way.

This in turn increases the disadvantage of excessively high Stoving temperatures, because those produced from the less reactive isocyanate group Urethanes or

substituted ureas naturally decap at even higher temperatures, so that even higher crosslinking temperatures are used when curing the lacquer Need to become. In addition, the reaction of the epoxy resins with diisocyanates Hydroxyl groups of the epoxy resin are consumed, which are then used for the crosslinking reaction are no longer available.

It has now been found, surprisingly, that these disadvantages can be overcome the invention avoids. The invention relates to curable, cationic modification products of epoxy resins, which are characterized by a content of -hydroxyalkylcarbamide ester groups are, the amide group of which is derived from a polyamine with at least two primary and / or secondary amino groups, and optionally additionally tertiary Amino groups, two of whose nitrogen bonds are occupied by hydrocarbon radicals are, the resins as such or in an acid protonated, in water or aqueous-organic systems. present in dissolved form and possibly customary Contain additives, and wherein at least 70% of the epoxy groups are brought to implementation are.

The invention also relates to a method for producing such Modification products, which is characterized in that polyamines with at least two primary and / or secondary amino groups partly so far with cyclic Alkylene carbonates are converted to P-Hydroxyalkylcarbadestern that at least a primary or secondary amino group is retained, and then the remaining ones Amine functions added to epoxy resins or that amine-functional derivatives of Epoxy resins containing primary and / or secondary amine functions with cyclic ones Alkylene carbonates to synthetic resins containing p-hydroxyalkylcarbamide ester groups are reacted, the epoxy groups optionally also before, during or after their reactions additionally with polyamines, which have a tertiary and also at least contain a primary or secondary amino group.

The invention finally relates to the use of the aforementioned Modification products, especially those containing either tertiary amino groups and / or contain curing catalysts, for the production of moldings, in particular Surface coatings.

It is known that cyclic alkylene carbonates, e.g. B.

Ethylene carbonate, propylene carbonate or butylene carbonate, the derivatives of 1,2-glycols are, in ammonia, primary or secondary amines smooth to the corresponding »-Hydroxyalkyl carbamide esters add. If you use polyamines, preferably those which contain at least two primary and / or secondary amine functions, preferably but at least one primary, and selects the proportions so that at least an amine function, as a rule, it is a secondary, remains, these adducts can be added to the epoxy groups of epoxy resins. It is Z. B. but also possible, initially by reacting epoxy resins with the above Polyamines to form synthetic resins that are at least secondary and optionally primary Amine functions contain, and then add, taking with cyclic alkylene carbonates basically the same reaction products are formed.

All epoxy resins that can be used as epoxy resins contain at least one epoxy group per molecule.

Epoxy resins made from diphenylolalkanes or higher are preferred Polyphenylene alkanes such as novolaks and epihalohydrins or dihalohydrins, preferably epichlorohydrin can be produced. Other suitable epoxy resins are those that result from the reaction of the same Ilydrine with polyhydric alcohols or polyglycol ethers or by epoxidation of double bonds, e.g. B. by epoxidation of unsaturated fatty oils or unsaturated hydrocarbons.

For the preparation of the ß-hydroxyalkyl carbamide esters, for. B. Polyamines with hydrocarbon radicals of 2 to 8 carbon atoms such as ethylene, propylene, Butylenediamine and hexylenediamine, furthermore dipropylenetriamine, tripropylenetetramine, dibutylenetriamine, Dihexylenetriamine, aromatic HAmines [with aliphatically bonded NII 2 groups, such as Xylylenediamine and its hydrogenation products, the various cyclohexylenediamines, but preferably dialkylenetriamines and / or trialkylenetetramines, their alkylene radicals each contains 2 to 6 carbon atoms, in particular diethylenetriamine and / or triethylenetetramine or mixtures of these amines are used. It is possible to be part of the primary To mask amine functions.

This is expediently done by reaction with ketones to give Schiff's Bases.

The epoxy resin-β-hydroxyalkyl-carbamide ester adducts produced in this way are already cationic resins and can be converted into a water-soluble form with acids be transferred.

The base strength of the amine moieties contained in these resins but is usually weak. To reinforce the cationic character, can but it would therefore be advisable to incorporate stronger amine functions. For this it is advantageous not to implement all epoxide groups with the alkylene carbonate adducts, but part for a further reaction with such amines and / or alkanolamines reserve a tertiary amine function in addition to the primary and / or secondary amine function Contain amine function. These are, for example, dialkylaminoalkylamines, in particular Dimethylaminopropylamine; N, N-dialkylamino- (N'-alkyl-) alkylamines or N, N-dialkylamino- (N'-alkanol-) alkylamines ) Alkylamines, e.g. B.

N, N-dimethylamino (N'-hydroxyethyl) propylamine. These amines can also be substituted in the main chain, such as the z. B for the N, N-dimethylamino- (N'-methylamino-) 2-hydroxypropylamine the case is. In this way one obtains modification products that additionally contain tertiary amino groups, two of whose nitrogen bonds are through hydrocarbon radicals are occupied.

Another way to increase the cationic self is consists in the »-hydroxyalkyl carbamide ester groups with such compounds implement the at least one primary apart from at least one tertiary amino group and / or secondary amino group and / or hydroxyl group. In this way urea and / or urethane groups are obtained from the garbamide ester groups. The polyamines listed above, among others, are suitable for this purpose.

But it is also possible to use compounds that except at least one tertiary amino group as functional groups only hydroxyl groups contain. Examples of such compounds are N, N-dialkylamino (N ', N'-dialkanol) -alkylamines or polyethers, which are produced by the reaction of amines, the except at least a tertiary amino group, at least one primary and / or secondary 'amino group contain, are prepared with alkylene oxides, preferably propylene oxides.

To change the dissolving properties and to control the correct one In addition, such amine adducts of monofunctional ones can have a degree of hydrophilicity or hydrophobicity Epoxy compounds are built into the resin that still have at least one primary or contain secondary amino group. Such amine adducts can by reaction of polyamines containing at least two non-tertiary, preferably two primary amino groups contained in the molecule, with a) glycidyl esters; of saturated and / or olefinic unsaturated fatty acids or b) optionally substituted alkylene oxides, such as Aryl or alkyl glycidyl ethers are produced.

Polyaminoamides can be incorporated into the resin for the same purpose. the at least one drimary and / or second contain the amine function. These Pol95-mide can be prepared by adding saturated or olefinically unsaturated mono- or polycarboxylic acids with polyfunctional amines, e.g. B. the above, are implemented.

The reaction between cyclic alkylene carbonate and amine can be in Substance or in organic or aqueous solution. She's already running at Room temperature falls, but then takes several days. It is preferable at elevated levels Temperature, preferably at 40 to 1200C and especially between 60 and 1000C work. At the higher temperatures, the reaction is usually after half a time completed in about 5 hours; the same applies to the reaction of the obtained Reaction products with die'Epoxidharzen and any implementation carried out with additional amine8 and / or epoxy compounds. The latter can be in Solvents. Solvents that can be used here are or polyhydric alcohols, ketones, esters, ethers, partial or complete glycol ethers, Acetals.

To increase the cationic properties of the invention Resins, it is possible to introduce additional amino groups into the resin by adding in first stage polyamines which contain at least two amino groups, of which at least one is tertiary and the other is primary or secondary, or those compounds those other than at least one primary or secondary or tertiary amine function still contain one or more hydroxyl groups, some with polyisocyanates implemented and the remaining isocyanate groups in the second stage with the OH groups or any primary or secondary amino groups of the modified one still present Epoxy resin are further reacted.

Suitable polyisocyanates are, for. B. 2,4- or 2,6-toluylene- diisocyanate, xylylene diisocyanate, diphenylmethy + -i4, '- diiso- cyanate, triphenylmethyl-4,4 ', 4 "-triisocyanate, polyphenylpolymethyl isocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 2,2,4 (2,4,4) -trimethylhexamethylene diisocyanate, methylcyclohexyl diisocyanate, dicyclohexylmethyl diisocyanate, diethyl fumarhexyl isocyanate (3-methyl isocyanate, bis- 4-isocyanatocyclohexyl-) methane, 2,2-bis- (4-isocyanatocyclohexyl-) propane, the methyl ester of lysine diisocyanate, the biuret of hexamethylene diisocyanate, diisocyanates of dimeric acids, 1-methylbenzene-2,4,5-triisocyanate, biphenyl-2 , 4,4'-triisocyanate, Tr <phenyinothntriisyti, the triisocyanate of 3 moles of hexamethylene diisocyanate and 1 mole of water with 16% NCO content and other compounds containing at least two NCO groups per molecule.

It is also possible to have additional amino groups in the form of partial or complete reaction products of polyepoxides, e.g. B. Diepoxiden, on the one hand and polyamines, on the other hand, which are both tertiary and secondary and / or primary Contain amine functions via primary and / or secondary ones still present in the resin molecule To introduce amino groups.

The weight ratios between epoxy resin, p-hydroxyalkyl carbamide ester derivative and, if applicable, the other compounds can be varied within wide limits. Preferably at least 80% and particularly advantageously at least 90-95% of the epoxy groups are reacted in the products according to the invention.

To be converted into a water-soluble form, the inventive Resins are protonated. The selection of the acid used is basically irrelevant; however, it is preferred low molecular weight organic mono- or polycarboxylic acids to use, which may still contain hydroxyl groups. To be named z. B. formic acid, acetic acid, propionic acid, lactic acid, gluconic acid, oxalic acid.

Phosphoric acids, especially orthophosphoric acid and its acidic esters, can also be used. The acids can be used before, during or after Resin formation can be added.

The cationic resins according to the invention are in principle self-crosslinking. They are crosslinked at temperatures of at least 110 ° C, preferably from 120 ° C, provided these resins are strongly basic, as it is especially after the incorporation of tertiary ones Amino groups is the case. The rate of crosslinking can vary with these resins can be accelerated by using catalysts. Metal salts are particularly suitable like the salts of lead, tin, iron, manganese, cobalt, calcium or barium with monocarboxylic acids, e.g. B.

Octoate /, Neodecanoatet, Laurate, Oleaten, StearateZ and Naphthenatep '. The weaker basic resins according to the invention crosslink only at higher temperatures, from about 1800C, and need to crosslink at lower temperatures, z. B. ab 1100C or from 12000, mandatory the addition of catalysts, e.g. B. the above. The resins are therefore preferably used in the form that they are either tertiary Contain amino groups and / or curing catalysts.

The resins according to the invention are usually solid, but sometimes viscous. You can in substance, the solid z. B.

in powder mixtures or from organic solvents for production of moldings, especially. flat like bonds and coatings, but are and are also used for impregnations. highly elastic after networking and chemically resistant. The particular advantage of the resins is that they are converted into a water-soluble form after the addition of acids and as an aqueous form or organic-aqueous colloidal systems can be used. The application can be done using the methods customary in paint technology by brushing on, rolling on, Applying a doctor blade, spraying on. The aqueous or aqueous organic synthetic resin solutions but can also be used in cataphoretic dip painting and by electrical Electricity can be deposited.

For the use of the resins according to the invention as a lacquer, that is to say for production of coatings, they can be in substance, as solutions, or aqueous-colloidal solutions Dispersions present resins with pigments, fillers or other usual resins Supplements are provided. In particular, such organic substances are included as additives and to understand synthetic resins that are used in paint technology to improve paint technology Properties are used. These are z. B.

Epoxy resins, epoxy resin dispersions, ester resins, polyglycol ethers, non-volatile or non-volatile solvents. These substances can even have cationic properties, but this is not mandatory.

The resins according to the invention are used in the manufacture of coatings used on any substrate as long as it has thermal stability, which is above the crosslinking temperature. When using for cataphoretic With dip coatings, the substrates must be electrically conductive.

In the following examples, T denotes parts by weight and% denotes percentages by weight. The viscosity is determined in the resulting form at 20 ° C according to DIN 53015.

Examples 1,332.4 T of one made from diphenylolpropane and epichlorohydPir.

built-up epoxy resin with an epoxy equivalent of 475 dissolved in 221.6 T methyl ethyl ketone. In another reaction vessel, 77.3 T diethylenetriamine dissolved in 225 T ethyl acetate and added to the solution heated to 4000 76.5 T propylene carbonate given. The approach warmed up slc-h as a result of the exothermic Response to about 8,000. This temperature was held for three hours. Afterward the reaction solution was transferred from this second reaction vessel to the first reaction vessel given and the mixture was stirred at 80 ° C. for three hours. 933 T of a 60% strength fell Resin solution which had a viscosity of 15,000 mPa.s.

100 T of this resin solution were mixed with 2 T of a lead octoate solution, the Containing 27% lead, mixed and this paint with a wet film thickness of 100 / um mounted on five glass plates. After 30 minutes of flashing off, these were each 30 minutes heated at 130, 140, 150, 160 or 1700C in the drying cabinet. All paint films When cut with a knife, they proved to be viscoplastic and solvent-resistant. They endured 100 double wipes with a cotton ball soaked in acetone.

100 parts of the lacquer solution mixed with lead octoate were treated with methyl ethyl ketone Diluted to a viscosity of 15 DIN-s and dip-coated galvanized iron sheets with it. The films heated in a drying cabinet at 130.degree. C. for 20 minutes were viscoplastic and lasted an impact depression of 70 inches and withstood in parallel tests for 30 minutes long 800C hot 2gier caustic soda and 1000C hot 2% acetic acid.

2. 380 T of an epoxy resin based on diphenylolpropane and epichlorohydrin having an epoxy equivalent of 950 and an average molecular weight from 1900 were dissolved in 253.2 T of ethyl acetate. In another reaction vessel were 20.6 T of diethylenetriamine dissolved in 40.8 T of ethyl acetate and added to that at room temperature given mixture 40.7 T propylene carbonate. Taking advantage of the exothermic The reaction was heated to 80 ° C. and this temperature was maintained for three hours. then the reaction mixture was transferred from the second reaction vessel to the first reaction vessel given and the mixture was stirred at 80 ° C. for three hours. Then it was cooled to 400C and gave 16.8 T of N, N-dimethylamino (N'-hydroxyethyl) propylamine and stirred 600C until the batch had a viscosity of 130,000 mPa.s. This takes a while four hours. The solution was diluted to 50% with 150 parts of methyl ethyl ketone. These Solution had a viscosity of 13,000 mPa.s.

200 parts of the 50% solution were mixed with 5 g of 50% acetic acid and diluted with 240 T water. A colloidal solution was created that had a viscosity of 230 mPa.s.

This lacquer solution was roller lacquered onto degreased, tinned Steel sheet applied and crosslinked for 20 minutes at 1300C. The thickness of the 'branded Lacquer film was -8 / µm.

The specimens kept an impact depression of 70 inches undamaged and withstood two hours of 2% acetic acid in parallel experiments at 1000C and two hours of 2% sodium hydroxide solution at 800C.

3. In a reaction vessel equipped with a stirrer and thermometer, 206 T of diethylenetriamine dissolved in 409 T of diethylene glycol dimethyl ether and stored at 50 ° C 408 T propylene carbonate were added. The temperature rose to 80OC and became three Held at 80 ° C. for hours. Then there was the implementation completed. It 1023 T of a solution I were obtained, which had a solids content of 60% (1 h / 1350C) owned.

396 parts of the glycidyl ester of isononanoic acid were dissolved in 60 parts of diethylene glycol dimethyl ether dissolved, 140 T hexamethylenediamine added and in a with thermometer and stirrer The reaction vessel provided is heated to 140 ° C. for two hours.

Then it was cooled down. 596 parts of a 90% strength solution II were obtained (Residue: 1 h / 135 ° C) 760 T of an epoxy resin based on diphenylolpopane and Epichlorohydrin with an epoxy equivalent weight of 475 were in a stirrer and thermometer. equipped reaction vessel in a mixture of equal parts Dissolved 1,2-propylene glycol, methyl isoamyl ketone and diethylbenzene and brought to 80 ° C. Then 272 T of solution 1 and 159 T of solution II were added and the mixture Stirred for three hours at 80.degree. 334 parts of methyl isoamyl ketone and 15.4 parts of acetic acid were then added and 24.5 T dimethylaminopropylamine and stirred for a further two hours at 80.degree. After cooling to 20 ° C., a 60% strength solution III of a water-dilutable was obtained Synthetic resin with a viscosity of 22,000 mPa.s.

To produce a cataphoresis bath, the mixture was diluted with stirring 200 T of solution III with 800 T of deionized water.

The aqueous colloidal solution had a pH of 8.8 and a conductivity of 463 / uS (microsiemens) (both values measured at 200C). By adding 1.3 With acetic acid, the bath was set to a conductivity of 1,200 μS and a pH of 7.9 a. A degreased sheet steel was used as the anode in a cataphoresis cell and a phosphated steel sheet attached as cathode. The cataphoretic coating was carried out at 250C with a voltage of -280 volts and lasted 1.5 minutes. The sheet metal connected as the cathode was removed from the cell and rinsed with water. After drying the sheet with an air jet, the Coating Baked in a circulating air drying cabinet at 1300C for 20 minutes. It formed a hard, glossy, viscoplastic coating with a layer thickness of 21 / um on the front and back. The baked film was resistant to organic Solvent and withstood the acetone test.

720 T of solution III were made with 108 T of titanium dioxide and 8.6 T of lead silicate rubbed on a three roller and diluted with 30,010 T deionized water. -The aqueous colloidal solution had a pH of 8.9 and a conductivity of 830 / uS (both Values measured at 200C). By adding 0.9 T acetic acid, a pH of 7.5 and set a conductivity of 1250 / uS. The pigmented resin solution was in a cataphoresis cell at 250C in the same way as above for a voltage deposited by 230 volts. After rinsing the cataphoretically coated sheet and drying with compressed air was 20 minutes in a circulating air drying cabinet at 135ob burned in. The layer thickness on the front and back was 19 μm.

The Erichsen indentation according to DIN 53156 gave a value of 5.8 mm and the impact depression according to ASTM -} - 2794 has a value of 25 incheslb. In the salt spray test According to ASTM-B-117-64 / 5% saline solution at 35 ° C., the test panels showed after 500 and 1000 hours of exposure, neither on the edge nor on the cross-cut, signs of rust underneath. The degree of blistering of the test panels according to DIN 53209 showed the best possible value M O G 0.

Claims (10)

PATENT CLAIMS: Curable, cationic modification products from Epoxy resins, characterized by a content of »-hydroxyalkylcarbamide ester groups, the amide group of which is derived from a polyamine with at least two primary and / or derived from secondary amino groups, and optionally also tertiary amino groups, two of whose nitrogen bonds are occupied by hydrocarbon radicals, with the resins as such or in a protonated by acid, in water or aqueous-organic Systems are present in dissolved form and may contain customary additives and wherein at least 70% of the epoxy groups are reacted. 2. Modification products according to claim 1, characterized in that that they still contain units that a) by reacting polyaminoamides that contain at least one primary and / or secondary amine function, with epoxy groups are formed or b) by reacting polyamines of those mentioned in claim 1 Kind with monofunctional epoxy compounds are made in such a way that still at least one primary or secondary amino group is retained. 3. Modification products according to claim 1 or 2, characterized in that that they are replaced by compounds which except at least one tertiary amino group at least contain a primary and / or secondary amino group and / or hydroxyl groups, are chemically and / or physically modified. 4. Modification products according to one or more of claims 1 to 3, characterized in that the amide group of the »-Hydroxyalkylcarbamidestergruppen derived from dialkylenetriamine and / or trialkylenetetramine, the alkylene radical each contains 2 to 6 carbon atoms. 5. Modification products according to one or more of claims 1 to 11, characterized in that the hydroxyl groups or primary and / or secondary amino groups by polyisocyanates and / or Epoxy compounds are modified. 6. Modification products according to one or more of claims 1 to 5, characterized in that they also contain curing catalysts. 7. Modification products according to one or more of claims 1 to 6, characterized in that at least 90 to 95% of the epoxy groups for Implementation are brought. 8. Process for the preparation of curable, cationic modification products of epoxy resins according to one or more of claims 1 to 7, characterized in that that some polyamines with at least two primary and / or secondary amino groups as far as reacted with cyclic AlkyAencarbonaten to ß-Hydroxyalkylcarbamidestern that at least one primary or secondary amino group is retained, and then the remaining amine functions on epoxy resins added or that amine-functional derivatives of epoxy resins that have primary and / or secondary amine functions contain, with cyclic alkylene carbonates to »-Hydroxyalkylcarbamidestergruppen containing synthetic resins are implemented, the epoxy groups optionally also before, during or after their reactions in addition with polyamines, the one contain tertiary and also at least one primary or secondary amino group, implemented. 9. The method according to claim 8, characterized in that in addition Amino groups are introduced into the resin by, in the first stage, polyamines, which contain at least two amino groups, of which at least one is tertiary and the others are primary or secondary, or those compounds that except at least an amine function still contain one or more hydroxyl groups, sometimes with Polyisocyanates implemented and the remaining isocyanate groups in further stage with the OH groups or any primary or secondary ones still present Amino groups of the modified epoxy resin are reacted further. 10. Use of the modification products according to one or more of claims 1 to 7, in particular those containing either tertiary amino groups andtor contain curing catalysts, for the production of moldings, in particular Surface coatings.