DE3246812C2 - - Google Patents

Description

The invention relates to curable, cationic modification products of epoxy resins which, as a crosslinking principle, contain β- hydroxyalkyl carbamide esters and optionally also tertiary amine groups, are made water-soluble and can also be used in cataphoretic dip coating.

It is known to use epoxy resins with amines, carboxylic acids, melamine resins, Phenolic resins, urea resins and others to network. Cationic epoxy resin derivatives contained in usually amine groups, which after protonization become a transfer allow in an aqueous phase. Such resins can from the aqueous solutions in cataphoretic dip painting by applying direct current to electrical conductive substrates are deposited. For your networking can not, but amines and free carboxylic acids but certain polyfunctional carboxylic acid esters are used will. Also melamine resins, phenolic resins and urea resins are useful, but are usually used as precondensates applied. This preferred embodiment does eliminate paint disadvantages, but leads to high molecular weights and thus to a viscosity increase that is often undesirable.

This also provides self-crosslinking epoxy resin derivatives forth that polyisocyanates to the hydroxyl groups or reactive amine groups of the epoxy resin modification product partially added and then capped. As a capping agent usually serve with alcohols or substances Amine groups. It is also possible to use amine free epoxy resins or to implement their descendants with polyisocyanates and / or cationic groups, which also act as capping agents serve on isocyanate groups, e.g. B. the leftover, to add.  

In this technically carried out process, Disadvantages due to the poor manageability of the isocyanates. These compounds are highly toxic and against water and compounds containing hydroxyl groups are sensitive. In the presence of strong bases, the isocyanate groups tend also for polymerization. The main disadvantage of that Resins produced is in the high Decapping temperature; Networking under practical conditions are usually above 170 ° C, but usually at even higher Temperatures possible. In order to add the isocyanate undesirable molecular enlargements to the epoxy resin to avoid using such diisocyanates, e.g. B. tolylene diisocyanate, their isocyanate groups have different levels of reactivity. The more reactive isocyanate group reacts with the epoxy resin sluggish remains, so that way Molecular enlargements can be avoided. This results again an increase in the disadvantage of the too high Baking temperatures, because those from the less reactive Isocyanate group produced or substituted urethanes Of course, ureas decap at even higher ones Temperatures, so that even higher Crosslinking temperatures when curing the paint must be applied. In addition, the reaction of epoxy resins with diisocyanates hydroxyl groups Epoxy resin consumed, which then for the Crosslinking reaction are no longer available.

It has now surprisingly been found that these disadvantages are avoided by the invention. The invention relates to curable, cationic modification products of epoxy resins, optionally in a mixture with customary additives, obtainable by partially reacting polyamines with at least two primary and / or secondary amino groups with cyclic alkylene carbonates to give β- hydroxyalkyl carbamide esters in bulk, in organic or aqueous solution, that at least one primary or secondary amino group is retained, subsequent addition of the remaining amine functions to epoxy resins or reaction of amino-functional derivatives of epoxy resins which contain primary and / or secondary amine functions with cyclic alkenyl carbonates to give β- hydroxyalkyl carbamate ester groups, at least 70% of the epoxy groups are implemented, and wherein the reaction takes place at temperatures from room temperature to 120 ° C.

The invention also relates to a process for the preparation of such modification products, which is characterized in that polyamines having at least two primary and / or secondary amino groups in bulk, in organic or aqueous solution are partially reacted with cyclic alkylene carbonates to give β- hydroxyalkyl carbamide esters in such a way that at least one primary or secondary amino group is retained, and then the remaining amine functions are added to epoxy resins or that amine-functional derivatives of epoxy resins which contain primary and / or secondary amine functions are reacted with cyclic alkylene carbonates to give β- hydroxyalkyl carbamate ester groups, with at least 70% of the Epoxy groups are brought to reaction and the reaction takes place at temperatures from room temperature to 120 ° C, and the epoxy groups optionally also before, during or after their reaction with polyamines, ie ie contain a tertiary and also contain at least one primary and / or secondary amino group.

The invention finally relates to the use of aforementioned modification products, in particular those which are either tertiary amino groups and / or Containing 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, which are derivatives of 1,2-glycols, add ammonia, primary or secondary amines to the corresponding β- hydroxyalkyl carbamide esters. If polyamines are used, preferably those which contain at least two primary and / or secondary amine functions, but preferably at least one primary, and the proportions are chosen so that at least one amine function, usually a secondary one, remains, these adducts can be added add the epoxy groups of epoxy resins. It is Z. However, it is also possible, for example, first to form synthetic resins which contain at least secondary and optionally primary amine functions by reacting epoxy resins with the above-mentioned polyamines, and then to add them, in principle giving the same reaction products with cyclic alkylene carbonates.

All epoxy resins can be used as epoxy resins, which contain at least one epoxy group per molecule. Epoxy resins made from diphenylolalkanes or higher polyphenylolalkanes such as novolaks and epihalohydrins or dihalohydrins, preferably epichlorohydrin getting produced. Other suitable epoxy resins are those by reacting the same hydrines with polyvalent ones Alcohols or polyglycol ethers or by epoxidation of Double bonds, e.g. B. by epoxidation of unsaturated fatty oils or unsaturated hydrocarbons will.

For the preparation of the β- hydroxyalkyl carbamide esters, e.g. B. polyamines with hydrocarbon radicals of 2 to 8 carbon atoms such as ethylene, propylene, butylene and hexylenediamine, also dipropylenetriamine, tripropylenetetramine, dibutylenetriamine, dihexylenetriamine, aromatic amines with aliphatically bound NH₂ groups, such as xylylenediamine and its hydrogenation products, the various Cyclohexylenediamines, but preferably dialkylenetriamines and / or trialkylenetetramines, the alkylene radical of which each contains 2 to 6 carbon atoms, in particular diethylenetriamine and / or triethylenetetramine or mixtures of these amines. It is possible to mask part of the primary amine functions. This is conveniently done by reaction with ketones to Schiff bases.

The epoxy resin- β- hydroxyalkyl-carbamide ester adducts thus produced are already cationic resins and can be converted into a water-soluble form using acids. However, the base strength of the amine groups contained in these resins is generally weak. In order to reinforce the cationic character, however, it may therefore be advisable to incorporate stronger amine functions. For this purpose, it is advantageous not to react all of the epoxy groups with the alkylene carbonate adducts, but to reserve a portion for further reaction with those amines and / or alkanolamines which, in addition to the primary and / or secondary amine function, contain a tertiary amine function. These are, for example, dialkylaminoalkylamines, especially dimethylaminopropylamine; N, N-dialkylamino (N'-alkyl) alkylamines or N, N-dialkylamino (N'-alkanol) 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. is the case with N, N-dimethylamino (N'-methylamino) 2-hydroxypropylamine. In this way, modification products are obtained which additionally contain tertiary amino groups, two of whose nitrogen bonds are occupied by hydrocarbon radicals.

Another possibility for increasing the cationic properties is to react the β- hydroxyalkyl carbamide ester groups with those compounds which, in addition to at least one tertiary amino group, contain at least one primary and / or secondary amino group and / or hydroxyl group. in this way, urea and / or urethane groups are obtained from the carbamide ester groups. The polyamines listed above are suitable for this. However, it is also possible to use compounds which, in addition to at least one tertiary amino group, contain only hydroxyl groups as functional groups. Examples of such compounds are N, N-dialkylamino- (N ′, N′-dialkanol) alkylamines or polyethers which are obtained by reaction of amines which contain at least one primary and / or secondary amino group in addition to at least one tertiary amino group with alkylene oxides, preferably propylene oxides are produced.

To change the release properties and to control the correct degree of hydrophilicity or hydrophobicity can such amine adducts of monofunctional epoxy compound in the resin, at least still contain a primary or secondary amino group. Such Amine adducts can be obtained by reacting polyamines that at least two non-tertiary, preferably two primary Contain amino groups in the molecule, with a) glycidyl esters of saturated and / or olefinically unsaturated fatty acids or b) optionally substituted alkylene oxides, such as Aryl or alkyl glycidyl ethers can be prepared.

Polyaminoamides can be incorporated into the resin for the same purpose be built that have at least one primary and / or second contain amine function. These polyaminoamides can be used be made by 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 bulk or in organic or aqueous solution respectively. It runs off at room temperature, needs but then several days. It is preferable to increase Temperature, preferably at 40 to 120 ° C and especially to work between 60 and 100 ° C. At the higher tem temperatures, the reaction is usually after half to about Completed 5 hours; the same applies to the reaction of the reaction products obtained with the epoxy resins and the possible implementation with additional aminic and / or epoxidic compounds. The latter can be carried out in solvents. Can be used as a solvent monohydric or polyhydric alcohols are used, Ketones, esters, ethers, partial or full glycol ether, acetale.  

To increase the cationic properties of the Invention According to the resins, it is possible to add amino groups to the Introduce resin by first stage polyamines that are at least contain two amino groups, at least of which one is tertiary and the others are primary or secondary, or those compounds other than at least one primary or secondary or tertiary amine another or contain several hydroxyl groups, some with polyisocyanates implemented and the remaining isocyanate groups in second stage with the OH groups or possibly still existing primary or secondary amino groups of the modified Epoxy resin to be reacted further.

Suitable polyisocyanates are e.g. B. 2,4- or 2,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, Triphenylmethane-4,4 ′, 4 ″ -triisocyanate, polyphenyl- polymethyl isocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 2,2,4 (2,4,4) trimethylhexamethylene diisocyanate, Methylcyclohexyl diisocyanate, dicyclohexyl methyl diisocyanate, Diethyl fumarhexyl isocyanate, bis (3-methyl-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, the triisocyanate from 3 moles Hexamethylene diisocyanate and 1 mole of water with 16% NCO content and another at least two NCO groups per molecule containing compounds.

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

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

In order to be converted into a water-soluble form, those according to the invention must be used Resins are protonized. The selection of the acid used is generally indifferent; it is however preferred, low molecular weight organic mono- or To use polycarboxylic acids, if necessary Contain hydroxyl groups. Are called z. B. formic acid, Acetic acid, propionic acid, lactic acid, gluconic acid, oxalic acid. Phosphoric acids, especially orthophosphoric acid and its acid Esters can also be used. The acids can NEN be added before, during or after resin formation.

The cationic resins according to the invention are in principle self-networking. They are cross-linked at temperatures of at least 110 ° C, preferably from 120 ° C, if these resins are strongly basic, as is especially the case after Incorporation of tertiary amino groups is the case. The network The rate of application of these resins can be increased by using accelerated by catalysts. Are particularly suitable Metal salts such as the salts of lead, tin, iron, manganese, Cobalt, calcium or barium with monocarboxylic acids, e.g. B. Octoate, Neodecanoate, Laurate, Oleate, Stearate and Naphthenates. The weaker basic ones according to the invention Resins only crosslink at higher temperatures, for example from 180 ° C, and require networking at lower Temperatures, e.g. B. from 110 ° C or from 120 ° C, mandatory the addition of catalysts, e.g. B. the above. Be the resins are preferably used in the form that they either tertiary amino groups and / or curing cata analyzers included.  

The resins of the invention are usually solid, sometimes but viscous. You can in substance, the solid z. B. in powder mixtures, or from organic solvents Manufacture of moldings, especially sheet-like Bonding and coating, but also for impregnation are used and are highly elastic after crosslinking and chemically resistant. The special one The advantage of the resins is that after the addition of Acids converted into a water-soluble form and as aqueous or organic-aqueous colloidal systems applied can be. The application can be used in the paint technology usual methods by spreading, rolling, knife coating, Spraying take place. The aqueous or aqueous-organic Resin solutions can also be used for cataphoretic dip coating applied and by electrical current are separated.

For the use of the resins according to the invention as lacquer, that is for the production of coatings, the substance, as Solutions, aqueous colloidal solutions or dispersions are present Resins with pigments, fillers or others usual additives. Among additives are especially such organic substances and synthetic resins understand that in paint technology to improve paint technology Properties are used. These are e.g. B. Epoxy resins, epoxy resin dispersions, ester resins, polyglycol ethers, non-volatile or non-volatile solvents. These Substances themselves can have cationic properties, however, this is not mandatory.

The resins of the invention are used in the manufacture of Coatings used on any substrates, provided that these have thermal stability above the cross-linking temperature lies. When used for cataphoretic Dip painting must make the substrates electrically conductive be.  

In the following examples, T means parts by weight and% Weight percent. The viscosity is in the accumulating Shape determined at 20 ° C according to DIN 53015.

Examples

1. 332.4 T one from diphenylolpropane and epichlorohydrin built-up epoxy resin with an epoxy equivalent of 475 were dissolved in 221.6 T methyl ethyl ketone. In another The reaction vessel was 77.3 T diethylenetriamine in 225 T. Dissolved ethyl acetate and the solution at 40 ° C Given 76.5 T propylene carbonate. The approach warmed up due to the exothermic reaction to about 80 ° C. This temperature was held for three hours. Then the Reaction solution from this second reaction vessel into the added the first reaction vessel and the mixture for three hours stirred at 80 ° C. 933 parts of a 60% resin solution fell 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 containing 27% lead mixed and this varnish with a wet film thickness of 100 µm on five glass plates raised. After airing for 30 minutes, these were each 30 min heated at 130, 140, 150, 160 or 170 ° C in the drying cabinet. All paint films proved to be the cut with the knife as tough elastic and were solvent resistant. They held 100 double wipes with one with acetone soaked cotton ball.

100 T of the lacquer solution mixed with lead octoate were mixed with Diluted methyl ethyl ketone to a viscosity of 15 DIN-s and galvanized iron sheets with it dip-coated. The 20 min Films heated in a drying cabinet at 130 ° C were tough elastic, endured an impact depression of 80.5 cm · kg and withstood parallel tests at 80 ° C for 30 min hot 2% sodium hydroxide solution and 100 ° C hot 2% Acetic acid.  

2. 380 parts of an epoxy resin based on diphenylpropane and epichlorohydrin with an epoxy equivalent of 950 and an average molecular weight of 1900 were in 253.2 T of ethyl acetate dissolved. In another reaction tube 20.6 T diethylenetriamine were dissolved in 40.8 T ethyl acetate and 40.7 T to the mixture at room temperature Given propylene carbonate. Taking advantage of the exothermic The reaction was heated to 80 ° C and this temperature was three Held for hours. Then the reaction mixture from the added the second reaction vessel into the first reaction vessel and the mixture was stirred at 80 ° C for three hours. Then cooled one from 40 ° C and 16.8 T N, N-dimethylamino (N'-hydroxyethyl) Propylamine and stirred at 60 ° C until the batch had reached a viscosity of 130,000 mPa · s. This takes a while four hours. The solution was treated with 150 T methyl ethyl ketone diluted to 50%. This solution had a viscosity of 13,000 mPa · s.

200 T of the 50% solution were mixed with 5 g of 50% acetic acid added and diluted with 240 T of water. It sent one colloidal solution, which had a viscosity of 230 mPa · s. This paint solution was applied to the degreased, tinned steel sheet applied and 20 minutes at 130 ° C networked. The thickness of the baked lacquer film was 8 µm.

The test specimens had an impact depth of 80.5 cm · kg undamaged and withstood parallel tests in two Hours of a 2% acetic acid at 100 ° C and two hours 2% sodium hydroxide solution at 80 ° C.

3. In a reaction vessel equipped with a stirrer and thermometer were 206 T diethylenetriamine in 409 T diethylene glycol dimethyl ether dissolved and at 50 ° C 408 T propylene carbonate admitted. The temperature rose to 80 ° C and became kept at 80 ° C for three hours. Then there was the implementation  completed. There were 1023 T of a solution I, the one Solids content of 60% (1 h / 135 ° C).

396 T of the glycidyl ester of isononanoic acid were in 60 T Diethylene glycol dimethyl ether dissolved, 140 T hexamethylene diamine added and in a provided with a thermometer and stirrer The reaction vessel was heated to 140 ° C. for two hours. Then it was cooled. 596 T of a 90% solution fell II on (residue: 1 h / 135 ° C).

760 T of an epoxy resin based on diphenylpropane and epichlorohydrin with an epoxy equivalent weight of 475 were in a equipped with stirrer and thermometer Reaction vessel in a mixture of equal parts 1,2- Dissolved propylene glycol, methyl isoamyl ketone and diethylbenzene and brought to 80 ° C. Then 272 T of solution I and 159 T of solution II added and the mixture for three hours stirred at 80 ° C. Then you gave 334 tons of methyl isoamyl ketone, 15.4 T acetic acid and 24.5 T dimethylaminopropylamine to and stirred for a further two hours at 80 ° C. After cooling at 20 ° C a 60% solution III of a water-dilutable was obtained Resin with a viscosity of 22,000 mPa · s.

To prepare a cataphoresis bath, dilute under Stir 200 T of solution III with 800 T of deionized water. The aqueous colloidal solution had a pH of 8.8 and one Conductivity of 463 µS (microsiemens) (both values at 20 ° C measured). By adding 1.3 T acetic acid the bath to a conductivity of 1200 µS and a pH from 7.9 a. In a cataphoresis cell were used as an anode degreased sheet steel and a phosphated as cathode Sheet steel attached. The cataphoretic coating was performed at 25 ° C with a voltage of 280 volts and took 1.5 minutes. The sheet metal connected as cathode was removed from the cell and rinsed with water. To The sheet was dried with an air jet  Coating at 130 ° C for 20 minutes in a forced air drying cabinet branded. A hard, shiny, tough-elastic coating with a layer thickness of 21 µm on the front and back. The branded film was resistant to organic solvents and resistant to it Acetone test.

720 T solution III were mixed with 108 T titanium dioxide and 8.6 T Lead silicate rubbed on a three-roller and with 3000 T deionized water. The aqueous colloidal solution had a pH of 8.9 and a conductivity of 830 µS (both values measured at 20 ° C). By adding 0.9 T Acetic acid had a pH of 7.5 and a conductivity of 1250 µS set. The pigmented resin solution was in a cataphoresis cell at 25 ° C in the same way as above deposited at a voltage of 230 volts. After rinsing of the cataphoretically coated sheet and drying with Compressed air was placed in a forced-air drying cabinet for 20 minutes Branded at 135 ° C. The layer thickness on the front and Back was 19 µm.

The Erichsen cupping according to DIN 53156 resulted in a value of 5.8 mm and the impact depression according to ASTM-D-2794 a value of 28.8 cmkg. Salt spray test according to ASTM-B-117-64 / The test panels showed 5% saline at 35 ° C after 500 and 1000 hours of exposure, neither on the edge signs of rusting on the cross cut. The degree of blistering the test plates according to DIN 53209 showed the best possible Value M O G O.

Claims (11)

1. Curable, cationic modification products of epoxy resins, optionally in a mixture with customary additives, obtainable by partially reacting polyamines with at least two primary and / or secondary amino groups with cyclic alkylene carbonates to give β- hydroxyalkyl carbamide esters in bulk, in organic or aqueous solution to the extent that at least a primary or secondary amino group is retained, subsequent addition of the remaining amine functions to epoxy resins or reaction of amine-functional derivatives of epoxy resins which contain primary and / or secondary amine functions with cyclic alkenyl carbonates to give synthetic resins containing β- hydroxyalkylcarbamate ester groups, at least 70% of the epoxy groups being used for the reaction are brought, and wherein the reaction takes place at temperatures from room temperature to 120 ° C. 2. Modification products according to claim 1, characterized characterized in that the resin has additional amino groups exhibits and has been obtained through partial turnover the epoxy groups before, during or after their turnover with the alkylene carbonate adducts with polyamines, the one tertiary and also at least one primary and / or contain secondary amino group. 3. Modification products according to claim 1, characterized characterized in that the resin has additional amino groups exhibits and has been obtained through partial turnover with polyamine adducts containing at least two Contain amino groups, at least one of which is tertiary and the others are primary and / or secondary, or from such connections that except at least one Amine function one or more hydroxyl groups  contain, and polyisocyanates, these adducts still have free isocyanate groups with the OH groups and / or with any primary or secondary still present Amino groups of the modified epoxy resin react. 4. Modification products according to claim 1, characterized characterized in that they still contain units which a) by reacting polyaminoamides which have at least one contain primary and / or secondary amine function, with Epoxy groups have been formed or b) by reaction of polyamines of the type mentioned in claim 1 with monofunctional epoxy compounds formed in the manner have been that at least one primary or secondary amino group is retained. 5. Modification products according to one or more of the Claims 1 to 4, characterized in that they Compounds other than at least one tertiary Amino group at least one primary and / or secondary Contain amino group and / or hydroxyl groups or have been implemented with these. 6. Modification products according to one or more of claims 1 to 5, characterized in that the amide group of the β- hydroxyalkyl carbamate ester groups is derived from dialkylenetriamine and / or trialkylenetetramine, the alkylene radical each containing 2 to 6 carbon atoms. 7. Modification products according to one or more of the Claims 1 to 6, characterized in that the Hydroxyl groups or primary and / or still present secondary amino groups by polyisocyanates and / or Epoxy compounds have been modified.   8. Modification products according to one or more of the Claims 1 to 7, characterized in that at least 90 to 95% of the epoxy groups have been reacted are. 9. A 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 polyamines with at least two primary and / or secondary amino groups in bulk, in organic or aqueous solution, to some extent with cyclic alkylene carbonates β- hydroxyalkyl carbamide esters are reacted in such a way that at least one primary or secondary amino group is retained, and then the remaining amino functions are added to epoxy resins or that amine-functional derivatives of epoxy resins which contain primary and / or secondary amine functions are reacted with cyclic alkylene carbonates to form β- hydroxyalkyl carbamide ester groups are, wherein at least 70% of the epoxy groups have been reacted and the reaction takes place at temperatures from room temperature to 120 ° C., and wherein the epoxy groups may also be before, during or n After their reactions, they are additionally reacted with polyamines which contain a tertiary and also at least one primary and / or secondary amino group. 10. Use of the modification products according to one or several of claims 1 to 8 for the production of Molded articles. 11. Use of the modification products according to one or several of claims 1 to 8 for the production of Surface coatings.