CA1329291C - Process for the preparation of binder dispersions capable of being cathodically deposited using crosslinking agents based on polyisocyanates blocked by amino groups - Google Patents
Process for the preparation of binder dispersions capable of being cathodically deposited using crosslinking agents based on polyisocyanates blocked by amino groupsInfo
- Publication number
- CA1329291C CA1329291C CA000582703A CA582703A CA1329291C CA 1329291 C CA1329291 C CA 1329291C CA 000582703 A CA000582703 A CA 000582703A CA 582703 A CA582703 A CA 582703A CA 1329291 C CA1329291 C CA 1329291C
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- Prior art keywords
- epoxide
- temperature
- mixture
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
- C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
- C08J3/07—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media from polymer solutions
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/40—High-molecular-weight compounds
- C08G18/64—Macromolecular compounds not provided for by groups C08G18/42 - C08G18/63
- C08G18/6407—Reaction products of epoxy resins with at least equivalent amounts of compounds containing active hydrogen
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
- C08G18/72—Polyisocyanates or polyisothiocyanates
- C08G18/80—Masked polyisocyanates
- C08G18/8061—Masked polyisocyanates masked with compounds having only one group containing active hydrogen
- C08G18/807—Masked polyisocyanates masked with compounds having only one group containing active hydrogen with nitrogen containing compounds
- C08G18/808—Monoamines
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
- C09D5/4419—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications with polymers obtained otherwise than by polymerisation reactions only involving carbon-to-carbon unsaturated bonds
- C09D5/443—Polyepoxides
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
- C09D5/4419—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications with polymers obtained otherwise than by polymerisation reactions only involving carbon-to-carbon unsaturated bonds
- C09D5/443—Polyepoxides
- C09D5/4434—Polyepoxides characterised by the nature of the epoxy binder
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2363/00—Characterised by the use of epoxy resins; Derivatives of epoxy resins
Abstract
Abstract Process for the preparation of binder dispersions capable of being cathodically deposited using crosslinking agents based on polyisocyanates blocked by amino groups The invention relates to a process for the prepara-tion of aqueous dispersions to be further processed to electrocoating paints with baking temperatures below 160°C
and baking times of ? 30 minutes, which dispersions contain modified epoxide-amine adducts as binders and polyiso-cyanates blocked by amino groups as crosslinking agents.
In this process, polyepoxides and compounds which contain one or more, preferably 2, hydroxyl groups per molecule are converted at higher temperatures and in the presence of catalysts to epoxide-containing intermediates.
A solvent or a mixture of solvents is then added with external cooling and the solution is then caused to boil under reflux, if necessary by application of a vacuum, until the temperature of the solution drops to 95°C to 20°C.
Amines are then added onto the epoxide groups which are still present in a free state in the epoxide resin and either a dispersion is prepared after the addition of the crosslinking agent by adding a water-acid mixture or the products are first dispersed and the crosslinking agent is added subsequently.
and baking times of ? 30 minutes, which dispersions contain modified epoxide-amine adducts as binders and polyiso-cyanates blocked by amino groups as crosslinking agents.
In this process, polyepoxides and compounds which contain one or more, preferably 2, hydroxyl groups per molecule are converted at higher temperatures and in the presence of catalysts to epoxide-containing intermediates.
A solvent or a mixture of solvents is then added with external cooling and the solution is then caused to boil under reflux, if necessary by application of a vacuum, until the temperature of the solution drops to 95°C to 20°C.
Amines are then added onto the epoxide groups which are still present in a free state in the epoxide resin and either a dispersion is prepared after the addition of the crosslinking agent by adding a water-acid mixture or the products are first dispersed and the crosslinking agent is added subsequently.
Description
~ 27293-32 The invention relates to a process for the prepara-tion of aqueous dispersions that contain modified epoxide-amine adducts as binders and polyisocyanates blocked by amino groups as crosslinking agents. The aqueous dispersions can be further processed to electro-coating paints with baking temperatures below 160C and baking times not greater than 30 minutes.
Cathodic electro-coating is a painting process fre-quently used particularly for priming, in which water-thinnable synthetic resins carrying cationic groups are deposited on electri-i, 10 cally conducting objects with the aid of direct current. Binders which are suitable for the cathodic deposition contain predomin-antly amino groups which are neutralized with acids in order to render the binders soluble in water.
A particularly preferred group of binders is repre-sented by the group of binders which are based on modified epoxy resins. Binders of this type are disclosed, for example, in the following patent documents: US-PS 4,031,050, US-PS
3,799,854, US-PS 3,984,299, US-PS 4,252,703, US-PS 4,332,711 and DE-PS 3,108,073.
, ;
,-'' ' ' " ' ' - ~
~" - 2 - 1329291 They are crossLinkable by virtue of admixed poly-isocyanates blocked by amino groups. These crosslinking agents thus contain at room temperature urea groups (=
blocked isocyanate groups). The blocking components are then split off at elevated temperatures and the isocyanate groups are regenerated. Subsequently, these isocyanate groups may effect the crosslinking of the binders via the hydroxyl groups and/or the primary and/or secondary amino groups contained therein. Such non-selfcrosslinking binder systems represent the present state of the art. Their structure and preparation are described, for example, in DE-PS 3,108,073, particularly in Examples 1 to S, or in EP
; 74,634 A2, Example A.
The crosslinking agents used therein react, because of the structure of their blocking components, only at tem-- peratures above 160C. The method described in the examples can therefore be followed without any difficulties.
However, in recent years the demand has steadily - grown for crosslinking agents which become active at con-siderably lower baking temperatures. This is due in the automotive industry, for example, to the joint use of ,~
- plastic components in the construction of automobile ~ :, bodies.
Attempts have therefore been made to prepare suit-able blocked polyisocyanates as crosslinking agents for re-duced baking temperatures. A blocking component particularly suitable for this purpose is the secondary amino group.
Such crosslinking agents based on aliphatic and aromatic polyisocyanates having secondary dialkylamines as blocking components are described, for example, in DE-OS
3,311,516. However, if these crosslinking agents are used instead of the crosslinking agents described above, the resultant paint surface lacks reproducible properties and exhibits breakdown phenomena and poor flow-out.
It is thus the object of the invention to make available a process which would make it possible, even when using crosslinking agents with low baking temper-atures and modified epoxide-amine adducts as binders, to obtain aqueous dispersions which give rise, after being further processed to electrocoating paints, to reproduc-ible surfaces formed by cathodic electrocoating with very ~: good mechanical properties.
This object is achieved according to the inven-. 15 tion by a process for the preparation of aqueous binder/
crosslinking agent dispersions, wherein t1) (A) polyepoxides and (B) compounds which contain one or more, preferably . 2, hydroxyl groups attached to aromatic and/
or (cyclo)aliphatic molecular fragments per molecule, are reacted in the presence of catalysts at elevated temperatures, preferably at from 100 to 180C, to furnish Z5 (C) epoxide-containing intermediates;
Cathodic electro-coating is a painting process fre-quently used particularly for priming, in which water-thinnable synthetic resins carrying cationic groups are deposited on electri-i, 10 cally conducting objects with the aid of direct current. Binders which are suitable for the cathodic deposition contain predomin-antly amino groups which are neutralized with acids in order to render the binders soluble in water.
A particularly preferred group of binders is repre-sented by the group of binders which are based on modified epoxy resins. Binders of this type are disclosed, for example, in the following patent documents: US-PS 4,031,050, US-PS
3,799,854, US-PS 3,984,299, US-PS 4,252,703, US-PS 4,332,711 and DE-PS 3,108,073.
, ;
,-'' ' ' " ' ' - ~
~" - 2 - 1329291 They are crossLinkable by virtue of admixed poly-isocyanates blocked by amino groups. These crosslinking agents thus contain at room temperature urea groups (=
blocked isocyanate groups). The blocking components are then split off at elevated temperatures and the isocyanate groups are regenerated. Subsequently, these isocyanate groups may effect the crosslinking of the binders via the hydroxyl groups and/or the primary and/or secondary amino groups contained therein. Such non-selfcrosslinking binder systems represent the present state of the art. Their structure and preparation are described, for example, in DE-PS 3,108,073, particularly in Examples 1 to S, or in EP
; 74,634 A2, Example A.
The crosslinking agents used therein react, because of the structure of their blocking components, only at tem-- peratures above 160C. The method described in the examples can therefore be followed without any difficulties.
However, in recent years the demand has steadily - grown for crosslinking agents which become active at con-siderably lower baking temperatures. This is due in the automotive industry, for example, to the joint use of ,~
- plastic components in the construction of automobile ~ :, bodies.
Attempts have therefore been made to prepare suit-able blocked polyisocyanates as crosslinking agents for re-duced baking temperatures. A blocking component particularly suitable for this purpose is the secondary amino group.
Such crosslinking agents based on aliphatic and aromatic polyisocyanates having secondary dialkylamines as blocking components are described, for example, in DE-OS
3,311,516. However, if these crosslinking agents are used instead of the crosslinking agents described above, the resultant paint surface lacks reproducible properties and exhibits breakdown phenomena and poor flow-out.
It is thus the object of the invention to make available a process which would make it possible, even when using crosslinking agents with low baking temper-atures and modified epoxide-amine adducts as binders, to obtain aqueous dispersions which give rise, after being further processed to electrocoating paints, to reproduc-ible surfaces formed by cathodic electrocoating with very ~: good mechanical properties.
This object is achieved according to the inven-. 15 tion by a process for the preparation of aqueous binder/
crosslinking agent dispersions, wherein t1) (A) polyepoxides and (B) compounds which contain one or more, preferably . 2, hydroxyl groups attached to aromatic and/
or (cyclo)aliphatic molecular fragments per molecule, are reacted in the presence of catalysts at elevated temperatures, preferably at from 100 to 180C, to furnish Z5 (C) epoxide-containing intermediates;
(2) (D) a solvent or a mixture of solvents is added with cooling by a secondary circuit (for ex-ample cooling via cooling coils filled with heat transfer oil or water) and the resultant .
~ 4 ~ I3 29 29 ~
resin solution is caused to boil under reflux, if necessary by application of a vacuum, until the temperature of the solution drops to 95C to 20C;
~ 4 ~ I3 29 29 ~
resin solution is caused to boil under reflux, if necessary by application of a vacuum, until the temperature of the solution drops to 95C to 20C;
(3) (E) amines are added onto the epoxide groups which are still present in a free state in the epoxide resin and either (4a) these reaction products are dispersed in a water-acid mixture and the crosslinking agent (F) is ad-mixed, or (4b) the crosslinking agent (F) is mixed with these pro-ducts and this mixture is dispersed in a water-acid mixture.
In the first stage of the process according to the invention epoxide-containing intermediates are first prepared from the components (A) and (8) in the presence of catalysts.
Any compound whose molecule contains on average more than 1 epoxide group, may be used as the component (A). Preferred compounds are those which contain 2 epoxlde groups in the molecule and have a relatively low molecular weight of not more than 750, preferably 350 to 5ûO.
Particularly preferred epoxide compounds are poly-glycidyl ethers of polyphenols prepared from polyphenols and epihalohydrins. 8isphenol A may preferably be used as the polyphenol.
Polyglycidyl esters of polycarboxylic acids may also be used. Glycidyl adipate and glycidyl phthalate are typical examples.
- s 1329291 Hydantoin epoxides, epoxidized polybutadiene and polyepoxicle compounds which are obtained by epoxidation of an olefinically unsaturated alicyclic compound, are furthermore suitable.
; 5 Compounds which contain one or more, preferably 2, hydroxyl groups attached to aromatic and/or (cycLo)-aliphatic molecular fragments per molecule, are used as the component (8).
Compounds which are suitable as the component (~), include both low-molecular and high-molecular compounds.
Suitable low-molecular components (a) are phen-olic, aliphatic and/or polyfunctional alcohols of a molecular weight below 350.
Examples of these are:
diols, such as ethylene glycol, dipropylene glycol, triglycol, 1,2-propanediol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propaned;ol, 1,2-butanediol, 1,4-butanediol, 2-ethyl-1,4-butanediol, 2-.~ ~
butene-1,4-diol, 1,2-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2-hydroxyethyl hydroxyacetate, 2,2-dimethyl-3-hydroxypropyl 2,2-dimethyl-hydroxypropionate, 4,4'-methylenebiscyclohexanol and 4,4'-isopropylidenebiscyclohexanol. 2,2-Dimethyl-1,3-propanediol and 3-methyl-1,5-pentanediol are some of the preferred diols.
Examples of higher molecular components (~) are polyester polyols, polyether polyols or polycaprolac-tone polyols of various functionality and molecular weight.
- 6 _ 1329291 Polyalkylene ether polyols suitable as the com-ponent (B) correspond to the general formula:
r H ~ o -(CHR)n ¦ OH
in which R = hydrogen or a lower alkyl radical which may carry various substituents, n = 2 to 6 and m = 3 to 50 or even higher. Examples are poly(oxytetramethylene) glycols and poly(oxyethylene) glycols.
The preferred polyalkylene ether polyols are poly(oxytetramethylene) glycols of a molecular weight in the range from 350 to 1,000.
Polyester polyols may also be used as the com-ponent (8). The polyester polyols may be prepared by polyesterification of organic polycarboxylic acids or their anhydrides with organic polyols containing primary hydroxyl groups. The polycarboxylic acids and the poly-ols are usually aliphatic or aromatic dicarboxylic acids and diols.
The diols used for the preparation of the poly-esters include alkylene glycols such as ethylene glycol, butylene glycol, neopentyl glycol or other glycols such as cyclohexanedimethanol.
The acid component of the polyester consists pri-marily of low-molecular carboxylic acids or their anhyd-rides of 2 to 18 carbon atoms in the molecule. Suitable ~ _ 7 _ 1329291 acids are, for example, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydro-phthalic acid, adipic acid, azelaic acid, sebacic acid and glutaric acid. The anhydrides of these acids may also S be used, insofar that they exist.
Furthermore, it is also possible to employ poly-ester polyols derived from lactones, as the component (a)~
These products are obtained by the reaction of an e-capro-lactone with a polyol. Such products are described in US-PS 3,169,945.
The polylactone polyols obtained by the react;on, are distinguished by the presence of a terminal hydroxyl group and recurring polyester moieties, derived from the lactone. These recurring molecular moieties may corres-pond to the formula - C )n CH2 . .
in which n is at least 4, preferably 4 to 6, and the sub-stituent is hydrogen, an alkyl radical, a cycloalkyl ; radical or an alkoxy radical.
Compounds containing, for example, one or more basic nitrogen atoms may be employed as the catalyst.
Tertiary amines, such as, for example, N,N-di-methylbenzylamine, tributylamine, dimethylcyclohexylamineand dimethyl-C12/C14-amine (C12/C14 represents an aliphatic chain containing 12 to 14 carbon atoms) are preferably used.
The catalyst is usually used in an amount from 0.1 to 2% by weight, based on the intermediate produced from ,,, ~
the components (A) and (B).
The reaction between the components (A) and (B) is car-ried out at temperatures between 100 and 190C, preferably between 100 and 180C.
In the second stage of the process according to the invention a solvent or a mixture of solvents is added to the resin solution with cooling by a secondary circuit (for example cooling via cooling coils filled with heat transfer oil or water). Sol-vents preferably to be added are those which cannot react with the epoxide groups still present and/or which can in any case be later added as solvents to the electrocoating paint. Particularly preferred solvents are ketones such as, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, mesityl oxide; acet-,i ates such as, for example, propyl acetate, butyl acetate; ethers such as, for example, dioxane, dibutyl ether; aromatic compounds such as, for example, toluene, xylene, ethylbenzene or mixtures of the solvents. The resin solution is caused to boil by careful application of a vacuum. Any foaming is brought under control by an appropriate lowering of the vacuum. As the temperature decreases, ~ 20 the pressure is gradually lowered further to achieve uniform boil-- ing. If desired, further solvent may be added while the mixture cools, either continuously or in portions. The cooling is to reduce the temperature of the resin solution to a value in the range 95C`to 20C, preferably not less than 50C.
In stage (3), primary and/or secondary amines may be employed as the component (E), the secondary amines being parti-cularly preferred components (E).
The amine should preferably be a water-soluble ~ 9 - 1329291 compound. Examples of such amines are monoalkylamines and dialkylamines such as methylamine, ethylamine, pro-pylamine, butylamine, dimethylamine, diethyLamine, dipro-pylamine, methylbutylamine and the like. AlkanoLamines, such as, for example, methylethanolamine, diethanolamine and the like, are also suitable. Dialkylaminoalkylamines such as, for example, dimethylaminoethylamine, diethyl-aminopropylamine, dimethylaminopropylamine and the like, are likewise suitable. Low-molecular amines are used in the majority of cases, but it is also possible to employ higher-molecular monoamines.
Polyamines with primary and secondary amino groups may react with the epoxide groups in the form of their ketimines. The ketimines are prepared from the poly-amines in a known manner.
The amines may also contain other groups, but these must not interfere with the reaction of the amine with the epoxide group nor must they induce gelling of the reaction mixture.
The reaction between the amines and the compounds containing epoxide groups often commences just by mix;ng the coreactants. Depending on the desired course of the reaction - particularly to ensure that the reaction runs to completion - it is recommended to raise the reaction : 25 temperature to 50 to 150C in the course of the reaction.
The crosslinking agent tF) for reduced baking temperatures added to the last stage of the process ac-cording to the invention is a polyisocyanate blocked with amino groups. These crosslinking agents are prepared by ~"
"
- 10 - 132929~
reacting a polyisocyanate with the corresponding secon-dary amine. The isocyanates may be aliphatic or aromatic, aromatic isocyanates being preferred for crosslinking agents for reduced baking temperatures.
S Alkylene isocyanates such as, for example, tri-methylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, ethylidene diisocyanate and butylidene diisocyanate as ~ well as cycloalkylene isocyanates such as, for example, - 1,3-cyclopentane diisocyanate, 1,4-cyclohexane d;iso-i.l cyanate, 1,2-cyclohexane diisocyanate and isophorone di-isocyanate are typical examples of aliphatic polyiso-cyanates.
Arylene isocyanates such as, for example, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate and 1,4-naphthalene diisocyanate as well as alkarylene isocyanates such as, for example, 4,4'-diphenylmethane diisocyanate, 2,4-toluylene diisocyanate or 2,6-toluylene diisocyanate or a mixture of 2,4- and 2,6-toluylene di-isocyanates, 4,4'-toluidine diisocyanate and 1,4-xylylene - diisocyanate as well as substituted aromatic systems such as, for example, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate or chlorodiphenylene diisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene and 4,4'-diphenyldimethylmethane 2,2',5,5'-tetraisocyanate as well as polymerized isocyanates are typical examples '` '' :' . '~ .
.
11 - 13292~1 of aromatic polyisocyanates.
For crosslinking agents for reduced baking tem-peratures, secondary amines are preferably used for block-ing the isocyanate group.
Examples of suitable monoam;nes are particularly secondary aliphatic, cycloaliphatic or araliphatic amines with a boiling point below 200C, those with a boiling point between 100 and 200C being preferred. Examples of suitable secondary aliphatic amines are dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine and isomers thereof, such as, for example, diisopropylamine, as well as asymmetrical compounds, such as N-ethyl-1-propanamine. Examples of suitable cyclo-aliphatic and araliphatic amines are dicyclohexylamine and N-methylaniline.
The reaction is carried out under conditions custo-mary for isocyanate reactions; the reaction temperature may be from room temperature to about 150C. If the starting materials and the reaction product are liquids at reaction temperature, it is possible to carry out the reaction with-out solvent; however, the reaction is generally carried ?~ out in an inert solvent such as ether, ester, ketone or hydrocarbon.
The crosslinking agent described above may be added directly at the end of stage (3) of the process according to the invention and the resultant mixture then dispersed in a water/acid mixture; however, first dispersing the reaction products from stage (3) in a water/acid mixture and only then adding the crosslinking agent is preferred.
., , :, , ~ ' ~, ' .
Organic acids, such as, ~or example, formic acid, acetic acid or lactic acid, are employed for the preparation of the water/acid mixtures.
After preparation of the aqueous dispersion the sol-vent is preferably removed in vacuo at a temperature below 65C.
The procedure of the process according to the invention for the preparation of aqueous dispersions to be further processed to electro-coating paints with low baking temperatures is elucidat-ed in greater detail by the examples below. The percentages given are percentages by weight, unless indicated otherwise.
Example 1 The example below describes the synthesis of an epoxide-amine resin modified with a monophenol compound, the addi-tion of a crosslinking agent and the preparation of an aqueous dispersion of this mixture.
The crosslinking agent (I) is first prepared as follows: 2440 g of triisocyanurated hexamethylene diisocyanate are placed in a suitable reaction vessel in an atmosphere of nitro-gen. 850 g of methyl isobutyl ketone (MIBK) are added and the mixture is heated to 50C. 1560 g of di-n-butylamine are then added. The rate of the addition is controlled in such a manner that the temperature is kept to 60-70C. At the end of the addi-tion the temperature is raised to 75C, and maintained at this level for one hour; 150 g of n-butanol are then added. The product has a solids content of 80% (130C, 1 h). Both the NCO-and the amine equivalent are above 20,000.
' ' - 12a - 27293-32 To synthesize the epoxy resin, 1884 g of an epoxy resin based on bisphenol A with an epoxide equivalent weight (EEW) of 188, 286 g of bisphenol A, 623 g of dodecylphenol . .
, .:
~ . , "., . . ~ ~ .
and 147 9 of xyLene are placed in a double-walled reaction vessel which can be heated by means of heat transfer oil and is provided with a stirrer, a reflux condenser, a water sep-arator, an inlet tube for inert gas and a vacuum connection, S and the mixture is heated to 110C. Traces of water are removed by distillation via a water separator in a continu-ous cycle by application of a slight vacuum. The reaction mixture is then heated to 130C and 11 9 of N,N-dimethyl-benzylamine are added, when the temperature briefly rises 1û to 150C. The mixture is then cooled to 130C and this temperature is maintained until an EEW of 1240 is reached (about S hours). To terminate the reaction, the reaction mixture is cooled via a secondary circuit and 225 9 of xylene and 52 9 of butylglycol are added in rapid succes-sion. The solution of the resin is caused to boil underreflux by careful application of a vacuum; any foaming is brought under control by an appropriate lowering of the vacuum. When a little later 95C is reached, the vacuum is released and 783 9 of a 70% solution of a reaction product obtained from 1 mole of diethylenetriamine and 2 mole of methyl isobutyl ketone (MIBK) in MIBK are added.
After the exothermic reaction has subsided, the reaction mixture is heated to 120C in the course of 30 minutes and ; this temperature is maintained for a further 2 hours. A
sample of the resin has the following characteristics:
Solids content (30 min, 180C): 80%
Base content: 1.47 meq/g of resin solids 910 9 of this resin solution are mixed with 390 9 of the crosslinking agent (I) and 19 9 of glacial acetic acid are added. 850 9 of water are then added in portions , . , . :, :
`
!' with stirring. The mixture is homogenized for a brief ; period and diluted with 960 9 of water added in small ~ portions to the final solids content.
; The dispersion is freed by subsequent vacuum dis-S tillation from volatile solvents, the solvent removed by distillation being replaced by equal amounts of water.
The dispersion is then filtered tsolids content 33.2%
(1 h, 130C)).
Example 2 The example below describes the synthesis of an epoxide-amine resin modified with a monophenol compound, the addition of a crosslinking agent and the preparation of an aqueous dispersion of this mixture.
The crosslinking agent (II) is first prepared as follows: 2088 9 of toluylene diisocyanate and 1746 9 of MIBK are placed in a reaction vessel in an atmosphere of - nitrogen and heated to 50C. 536 9 of trimethylolpropane are then added in portions. The temperature is maintained at SS-60C. At the end of the addition the reaction mix-ture is maintained at this temperature for 1 hour, is then cooled to 60C and 1450 9 of di-n-butylamine are added at such a rate that the temperature is maintained at 70-75C. The reaction is allowed to proceed for a further 1 hour after the end of the addition. The product has a solids content of 70%. The amine equivalent and the isocyanate equivalent are both above 20,000.
To synthesize the epoxy resin, the procedure of Example 1 is followed.
910 9 of the resin solution and 390 9 of the .
~''' ' ~. -'. ` , . ~
- 15 _ I 3 2 92 9I
cross-linking agent (II) are mixed and Z1 9 of glacial acetic ac;d are added. 850 9 of water are then added in portions with stirring. The reaction mixture is homogenized for a brief period and then diluted with 960 9 of water added in small portions to the final solids content.
The dispersions are freed by subsequent vacuum dis-tillation from volatile solvents, the solvent removed by distillation being replaced by equal amounts of water.
The dispersion is then filtered (solids content 33.4%
(1 h, 130C)).
Comparison example The procedure of Example 1 is followed until the - EE~ of 1240 is reached. 1785 9 of the crosslinking agent (I) and 783 9 of a 70% solution of a reaction product obtained from diethylenetriamine and methyl isobutyl ketone in methyl isobutyl ketone are added. The reaction mixture is adjusted to a temperature of 112C and this temperature is maintained for 1 hour.
19 9 of glacial acetic acid are added to 1200 9 of this resin solution and 850 9 of water are added in por-tions with stirring. The mixture is homogenized for a brief period and diluted with 960 9 of water added in small portions to the final solids content.
The dispersion is freed in subsequent vacuum dis-tillation from volatile solvents, the solvent removed bydistillation being replaced by equal amounts of water.
The dispersion is then filtered (solids content 35.1% (1 h, 130C)).
Electrocoating baths are prepared from the binder , :
:
. ~ .
~ - 16 - 1329291 dispersions described in Examples 1 and 2 and in the com-parison example with a gray pigment paste.
To prepare a gray pigment paste, 800 parts of butyl-glycol are added to 953 parts of a commercially available S epoxy resin based on bisphenol A (epoxide equivalent weight of 890) and the mixture is heated to 80C. 221 parts of a reaction product obtained from 101 parts of diethanolamine and 120 parts of 80% aqueous lactic acid are then added to the resin solution. The reaction is carried out at 80C
until the acid value has dropped below 1.
1800 parts of this product are mixed with 2447 parts of deionized water and this mixture is treated with 2460 parts of TiO2, 590 parts of an extender based on alu-minum silicate, 135 parts of lead silicate and 37 parts of carbon black. This mixture is ground in a millbase to a Hegman fineness of 5 to 7. 1255 parts of deionized water are then added in order to reach the desired paste con-sistency.
The electrocoating baths are obtained by mixing:
2280 parts of deionized water 25 parts of 10% acetic acid 1920 parts of aqueous crosslinking agent/epoxide-amine adduct dispersion 775 parts of pigment paste.
The deposition of the paint films is carried out at a bath temperature of 26C for 120 seconds. Zinc phosphated panels are connected as cathode for this purpose and coated.
The curing of the deposited films is carried out for 20 minutes in a circulating air oven at temperatures indicated in the ~ - 17 - 1 3 2 9 2 9 1 table together with deposition data.
The deposition results are summarized in the tables below:
Deposition data:
Deposition data Example 1 Example 2 Comparison example -Deposit;on voltage (V) 300 320 330 Film thickness t~m) 23 21 19 Baking temperature (C) 145 130 145 FORD throwing power (cm) 20.5 22 20 Mechanical properties:
Test method Example 1 Example 2 Comparison example . 15 Erichsen indentation (mm) 8 4 6 . Crosshatch O 0 (O best, 5 worst) -, Bending test pass pass pass . 20 Impact test : (m kg) 0.920.69 0.69 Flow-out 0.5 1.5 4.5 (O best, 5 worst) ,, - , . . .
In the first stage of the process according to the invention epoxide-containing intermediates are first prepared from the components (A) and (8) in the presence of catalysts.
Any compound whose molecule contains on average more than 1 epoxide group, may be used as the component (A). Preferred compounds are those which contain 2 epoxlde groups in the molecule and have a relatively low molecular weight of not more than 750, preferably 350 to 5ûO.
Particularly preferred epoxide compounds are poly-glycidyl ethers of polyphenols prepared from polyphenols and epihalohydrins. 8isphenol A may preferably be used as the polyphenol.
Polyglycidyl esters of polycarboxylic acids may also be used. Glycidyl adipate and glycidyl phthalate are typical examples.
- s 1329291 Hydantoin epoxides, epoxidized polybutadiene and polyepoxicle compounds which are obtained by epoxidation of an olefinically unsaturated alicyclic compound, are furthermore suitable.
; 5 Compounds which contain one or more, preferably 2, hydroxyl groups attached to aromatic and/or (cycLo)-aliphatic molecular fragments per molecule, are used as the component (8).
Compounds which are suitable as the component (~), include both low-molecular and high-molecular compounds.
Suitable low-molecular components (a) are phen-olic, aliphatic and/or polyfunctional alcohols of a molecular weight below 350.
Examples of these are:
diols, such as ethylene glycol, dipropylene glycol, triglycol, 1,2-propanediol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propaned;ol, 1,2-butanediol, 1,4-butanediol, 2-ethyl-1,4-butanediol, 2-.~ ~
butene-1,4-diol, 1,2-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2-hydroxyethyl hydroxyacetate, 2,2-dimethyl-3-hydroxypropyl 2,2-dimethyl-hydroxypropionate, 4,4'-methylenebiscyclohexanol and 4,4'-isopropylidenebiscyclohexanol. 2,2-Dimethyl-1,3-propanediol and 3-methyl-1,5-pentanediol are some of the preferred diols.
Examples of higher molecular components (~) are polyester polyols, polyether polyols or polycaprolac-tone polyols of various functionality and molecular weight.
- 6 _ 1329291 Polyalkylene ether polyols suitable as the com-ponent (B) correspond to the general formula:
r H ~ o -(CHR)n ¦ OH
in which R = hydrogen or a lower alkyl radical which may carry various substituents, n = 2 to 6 and m = 3 to 50 or even higher. Examples are poly(oxytetramethylene) glycols and poly(oxyethylene) glycols.
The preferred polyalkylene ether polyols are poly(oxytetramethylene) glycols of a molecular weight in the range from 350 to 1,000.
Polyester polyols may also be used as the com-ponent (8). The polyester polyols may be prepared by polyesterification of organic polycarboxylic acids or their anhydrides with organic polyols containing primary hydroxyl groups. The polycarboxylic acids and the poly-ols are usually aliphatic or aromatic dicarboxylic acids and diols.
The diols used for the preparation of the poly-esters include alkylene glycols such as ethylene glycol, butylene glycol, neopentyl glycol or other glycols such as cyclohexanedimethanol.
The acid component of the polyester consists pri-marily of low-molecular carboxylic acids or their anhyd-rides of 2 to 18 carbon atoms in the molecule. Suitable ~ _ 7 _ 1329291 acids are, for example, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydro-phthalic acid, adipic acid, azelaic acid, sebacic acid and glutaric acid. The anhydrides of these acids may also S be used, insofar that they exist.
Furthermore, it is also possible to employ poly-ester polyols derived from lactones, as the component (a)~
These products are obtained by the reaction of an e-capro-lactone with a polyol. Such products are described in US-PS 3,169,945.
The polylactone polyols obtained by the react;on, are distinguished by the presence of a terminal hydroxyl group and recurring polyester moieties, derived from the lactone. These recurring molecular moieties may corres-pond to the formula - C )n CH2 . .
in which n is at least 4, preferably 4 to 6, and the sub-stituent is hydrogen, an alkyl radical, a cycloalkyl ; radical or an alkoxy radical.
Compounds containing, for example, one or more basic nitrogen atoms may be employed as the catalyst.
Tertiary amines, such as, for example, N,N-di-methylbenzylamine, tributylamine, dimethylcyclohexylamineand dimethyl-C12/C14-amine (C12/C14 represents an aliphatic chain containing 12 to 14 carbon atoms) are preferably used.
The catalyst is usually used in an amount from 0.1 to 2% by weight, based on the intermediate produced from ,,, ~
the components (A) and (B).
The reaction between the components (A) and (B) is car-ried out at temperatures between 100 and 190C, preferably between 100 and 180C.
In the second stage of the process according to the invention a solvent or a mixture of solvents is added to the resin solution with cooling by a secondary circuit (for example cooling via cooling coils filled with heat transfer oil or water). Sol-vents preferably to be added are those which cannot react with the epoxide groups still present and/or which can in any case be later added as solvents to the electrocoating paint. Particularly preferred solvents are ketones such as, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, mesityl oxide; acet-,i ates such as, for example, propyl acetate, butyl acetate; ethers such as, for example, dioxane, dibutyl ether; aromatic compounds such as, for example, toluene, xylene, ethylbenzene or mixtures of the solvents. The resin solution is caused to boil by careful application of a vacuum. Any foaming is brought under control by an appropriate lowering of the vacuum. As the temperature decreases, ~ 20 the pressure is gradually lowered further to achieve uniform boil-- ing. If desired, further solvent may be added while the mixture cools, either continuously or in portions. The cooling is to reduce the temperature of the resin solution to a value in the range 95C`to 20C, preferably not less than 50C.
In stage (3), primary and/or secondary amines may be employed as the component (E), the secondary amines being parti-cularly preferred components (E).
The amine should preferably be a water-soluble ~ 9 - 1329291 compound. Examples of such amines are monoalkylamines and dialkylamines such as methylamine, ethylamine, pro-pylamine, butylamine, dimethylamine, diethyLamine, dipro-pylamine, methylbutylamine and the like. AlkanoLamines, such as, for example, methylethanolamine, diethanolamine and the like, are also suitable. Dialkylaminoalkylamines such as, for example, dimethylaminoethylamine, diethyl-aminopropylamine, dimethylaminopropylamine and the like, are likewise suitable. Low-molecular amines are used in the majority of cases, but it is also possible to employ higher-molecular monoamines.
Polyamines with primary and secondary amino groups may react with the epoxide groups in the form of their ketimines. The ketimines are prepared from the poly-amines in a known manner.
The amines may also contain other groups, but these must not interfere with the reaction of the amine with the epoxide group nor must they induce gelling of the reaction mixture.
The reaction between the amines and the compounds containing epoxide groups often commences just by mix;ng the coreactants. Depending on the desired course of the reaction - particularly to ensure that the reaction runs to completion - it is recommended to raise the reaction : 25 temperature to 50 to 150C in the course of the reaction.
The crosslinking agent tF) for reduced baking temperatures added to the last stage of the process ac-cording to the invention is a polyisocyanate blocked with amino groups. These crosslinking agents are prepared by ~"
"
- 10 - 132929~
reacting a polyisocyanate with the corresponding secon-dary amine. The isocyanates may be aliphatic or aromatic, aromatic isocyanates being preferred for crosslinking agents for reduced baking temperatures.
S Alkylene isocyanates such as, for example, tri-methylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, ethylidene diisocyanate and butylidene diisocyanate as ~ well as cycloalkylene isocyanates such as, for example, - 1,3-cyclopentane diisocyanate, 1,4-cyclohexane d;iso-i.l cyanate, 1,2-cyclohexane diisocyanate and isophorone di-isocyanate are typical examples of aliphatic polyiso-cyanates.
Arylene isocyanates such as, for example, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate and 1,4-naphthalene diisocyanate as well as alkarylene isocyanates such as, for example, 4,4'-diphenylmethane diisocyanate, 2,4-toluylene diisocyanate or 2,6-toluylene diisocyanate or a mixture of 2,4- and 2,6-toluylene di-isocyanates, 4,4'-toluidine diisocyanate and 1,4-xylylene - diisocyanate as well as substituted aromatic systems such as, for example, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate or chlorodiphenylene diisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene and 4,4'-diphenyldimethylmethane 2,2',5,5'-tetraisocyanate as well as polymerized isocyanates are typical examples '` '' :' . '~ .
.
11 - 13292~1 of aromatic polyisocyanates.
For crosslinking agents for reduced baking tem-peratures, secondary amines are preferably used for block-ing the isocyanate group.
Examples of suitable monoam;nes are particularly secondary aliphatic, cycloaliphatic or araliphatic amines with a boiling point below 200C, those with a boiling point between 100 and 200C being preferred. Examples of suitable secondary aliphatic amines are dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine and isomers thereof, such as, for example, diisopropylamine, as well as asymmetrical compounds, such as N-ethyl-1-propanamine. Examples of suitable cyclo-aliphatic and araliphatic amines are dicyclohexylamine and N-methylaniline.
The reaction is carried out under conditions custo-mary for isocyanate reactions; the reaction temperature may be from room temperature to about 150C. If the starting materials and the reaction product are liquids at reaction temperature, it is possible to carry out the reaction with-out solvent; however, the reaction is generally carried ?~ out in an inert solvent such as ether, ester, ketone or hydrocarbon.
The crosslinking agent described above may be added directly at the end of stage (3) of the process according to the invention and the resultant mixture then dispersed in a water/acid mixture; however, first dispersing the reaction products from stage (3) in a water/acid mixture and only then adding the crosslinking agent is preferred.
., , :, , ~ ' ~, ' .
Organic acids, such as, ~or example, formic acid, acetic acid or lactic acid, are employed for the preparation of the water/acid mixtures.
After preparation of the aqueous dispersion the sol-vent is preferably removed in vacuo at a temperature below 65C.
The procedure of the process according to the invention for the preparation of aqueous dispersions to be further processed to electro-coating paints with low baking temperatures is elucidat-ed in greater detail by the examples below. The percentages given are percentages by weight, unless indicated otherwise.
Example 1 The example below describes the synthesis of an epoxide-amine resin modified with a monophenol compound, the addi-tion of a crosslinking agent and the preparation of an aqueous dispersion of this mixture.
The crosslinking agent (I) is first prepared as follows: 2440 g of triisocyanurated hexamethylene diisocyanate are placed in a suitable reaction vessel in an atmosphere of nitro-gen. 850 g of methyl isobutyl ketone (MIBK) are added and the mixture is heated to 50C. 1560 g of di-n-butylamine are then added. The rate of the addition is controlled in such a manner that the temperature is kept to 60-70C. At the end of the addi-tion the temperature is raised to 75C, and maintained at this level for one hour; 150 g of n-butanol are then added. The product has a solids content of 80% (130C, 1 h). Both the NCO-and the amine equivalent are above 20,000.
' ' - 12a - 27293-32 To synthesize the epoxy resin, 1884 g of an epoxy resin based on bisphenol A with an epoxide equivalent weight (EEW) of 188, 286 g of bisphenol A, 623 g of dodecylphenol . .
, .:
~ . , "., . . ~ ~ .
and 147 9 of xyLene are placed in a double-walled reaction vessel which can be heated by means of heat transfer oil and is provided with a stirrer, a reflux condenser, a water sep-arator, an inlet tube for inert gas and a vacuum connection, S and the mixture is heated to 110C. Traces of water are removed by distillation via a water separator in a continu-ous cycle by application of a slight vacuum. The reaction mixture is then heated to 130C and 11 9 of N,N-dimethyl-benzylamine are added, when the temperature briefly rises 1û to 150C. The mixture is then cooled to 130C and this temperature is maintained until an EEW of 1240 is reached (about S hours). To terminate the reaction, the reaction mixture is cooled via a secondary circuit and 225 9 of xylene and 52 9 of butylglycol are added in rapid succes-sion. The solution of the resin is caused to boil underreflux by careful application of a vacuum; any foaming is brought under control by an appropriate lowering of the vacuum. When a little later 95C is reached, the vacuum is released and 783 9 of a 70% solution of a reaction product obtained from 1 mole of diethylenetriamine and 2 mole of methyl isobutyl ketone (MIBK) in MIBK are added.
After the exothermic reaction has subsided, the reaction mixture is heated to 120C in the course of 30 minutes and ; this temperature is maintained for a further 2 hours. A
sample of the resin has the following characteristics:
Solids content (30 min, 180C): 80%
Base content: 1.47 meq/g of resin solids 910 9 of this resin solution are mixed with 390 9 of the crosslinking agent (I) and 19 9 of glacial acetic acid are added. 850 9 of water are then added in portions , . , . :, :
`
!' with stirring. The mixture is homogenized for a brief ; period and diluted with 960 9 of water added in small ~ portions to the final solids content.
; The dispersion is freed by subsequent vacuum dis-S tillation from volatile solvents, the solvent removed by distillation being replaced by equal amounts of water.
The dispersion is then filtered tsolids content 33.2%
(1 h, 130C)).
Example 2 The example below describes the synthesis of an epoxide-amine resin modified with a monophenol compound, the addition of a crosslinking agent and the preparation of an aqueous dispersion of this mixture.
The crosslinking agent (II) is first prepared as follows: 2088 9 of toluylene diisocyanate and 1746 9 of MIBK are placed in a reaction vessel in an atmosphere of - nitrogen and heated to 50C. 536 9 of trimethylolpropane are then added in portions. The temperature is maintained at SS-60C. At the end of the addition the reaction mix-ture is maintained at this temperature for 1 hour, is then cooled to 60C and 1450 9 of di-n-butylamine are added at such a rate that the temperature is maintained at 70-75C. The reaction is allowed to proceed for a further 1 hour after the end of the addition. The product has a solids content of 70%. The amine equivalent and the isocyanate equivalent are both above 20,000.
To synthesize the epoxy resin, the procedure of Example 1 is followed.
910 9 of the resin solution and 390 9 of the .
~''' ' ~. -'. ` , . ~
- 15 _ I 3 2 92 9I
cross-linking agent (II) are mixed and Z1 9 of glacial acetic ac;d are added. 850 9 of water are then added in portions with stirring. The reaction mixture is homogenized for a brief period and then diluted with 960 9 of water added in small portions to the final solids content.
The dispersions are freed by subsequent vacuum dis-tillation from volatile solvents, the solvent removed by distillation being replaced by equal amounts of water.
The dispersion is then filtered (solids content 33.4%
(1 h, 130C)).
Comparison example The procedure of Example 1 is followed until the - EE~ of 1240 is reached. 1785 9 of the crosslinking agent (I) and 783 9 of a 70% solution of a reaction product obtained from diethylenetriamine and methyl isobutyl ketone in methyl isobutyl ketone are added. The reaction mixture is adjusted to a temperature of 112C and this temperature is maintained for 1 hour.
19 9 of glacial acetic acid are added to 1200 9 of this resin solution and 850 9 of water are added in por-tions with stirring. The mixture is homogenized for a brief period and diluted with 960 9 of water added in small portions to the final solids content.
The dispersion is freed in subsequent vacuum dis-tillation from volatile solvents, the solvent removed bydistillation being replaced by equal amounts of water.
The dispersion is then filtered (solids content 35.1% (1 h, 130C)).
Electrocoating baths are prepared from the binder , :
:
. ~ .
~ - 16 - 1329291 dispersions described in Examples 1 and 2 and in the com-parison example with a gray pigment paste.
To prepare a gray pigment paste, 800 parts of butyl-glycol are added to 953 parts of a commercially available S epoxy resin based on bisphenol A (epoxide equivalent weight of 890) and the mixture is heated to 80C. 221 parts of a reaction product obtained from 101 parts of diethanolamine and 120 parts of 80% aqueous lactic acid are then added to the resin solution. The reaction is carried out at 80C
until the acid value has dropped below 1.
1800 parts of this product are mixed with 2447 parts of deionized water and this mixture is treated with 2460 parts of TiO2, 590 parts of an extender based on alu-minum silicate, 135 parts of lead silicate and 37 parts of carbon black. This mixture is ground in a millbase to a Hegman fineness of 5 to 7. 1255 parts of deionized water are then added in order to reach the desired paste con-sistency.
The electrocoating baths are obtained by mixing:
2280 parts of deionized water 25 parts of 10% acetic acid 1920 parts of aqueous crosslinking agent/epoxide-amine adduct dispersion 775 parts of pigment paste.
The deposition of the paint films is carried out at a bath temperature of 26C for 120 seconds. Zinc phosphated panels are connected as cathode for this purpose and coated.
The curing of the deposited films is carried out for 20 minutes in a circulating air oven at temperatures indicated in the ~ - 17 - 1 3 2 9 2 9 1 table together with deposition data.
The deposition results are summarized in the tables below:
Deposition data:
Deposition data Example 1 Example 2 Comparison example -Deposit;on voltage (V) 300 320 330 Film thickness t~m) 23 21 19 Baking temperature (C) 145 130 145 FORD throwing power (cm) 20.5 22 20 Mechanical properties:
Test method Example 1 Example 2 Comparison example . 15 Erichsen indentation (mm) 8 4 6 . Crosshatch O 0 (O best, 5 worst) -, Bending test pass pass pass . 20 Impact test : (m kg) 0.920.69 0.69 Flow-out 0.5 1.5 4.5 (O best, 5 worst) ,, - , . . .
Claims (11)
1. A process for the preparation of an aqueous dispersion for use in the preparation of aqueous electro-coating paints, which process comprises:
(1) reacting (A) a polyepoxide and (B) a compound which contains one or more, hydroxyl groups attached to aromatic and/or (cyclo)aliphatic molecular fragments per molecule, in the presence of a catalyst at elevated temperature to furnish (C) an epoxide-containing intermediate;
(2) (D) adding a solvent or a mixture of solvents with external cooling and causing the resultant resin solution to boil under reflux, if necessary by application of a vacuum, until the temperature of the solution drops to 95°C to 20°C;
(3) (E) an amine onto the epoxide groups which are still present in a free state in the epoxide resin and either (4a) dispersing these reaction products in a water-acid mixture and admixing a crosslinking agent (F) which is a polyisocyanate blocked by amino groups, or (4b) mixing the crosslinking agent (F) with these reaction products and dispersing this mixture in a water-acid mixture.
(1) reacting (A) a polyepoxide and (B) a compound which contains one or more, hydroxyl groups attached to aromatic and/or (cyclo)aliphatic molecular fragments per molecule, in the presence of a catalyst at elevated temperature to furnish (C) an epoxide-containing intermediate;
(2) (D) adding a solvent or a mixture of solvents with external cooling and causing the resultant resin solution to boil under reflux, if necessary by application of a vacuum, until the temperature of the solution drops to 95°C to 20°C;
(3) (E) an amine onto the epoxide groups which are still present in a free state in the epoxide resin and either (4a) dispersing these reaction products in a water-acid mixture and admixing a crosslinking agent (F) which is a polyisocyanate blocked by amino groups, or (4b) mixing the crosslinking agent (F) with these reaction products and dispersing this mixture in a water-acid mixture.
2. The process as claimed in claim 1, wherein the poly-isocyanate is an aliphatic polyisocyanate.
3. The process as claimed in claim 1, wherein the poly-isocyanate is an aromatic polyisocyanate.
4. The process as claimed in claim 1, 2 or 3, wherein the substance used as solvent in stage (2) is a substance which does not react with the epoxide groups still present in the resin.
5. The process as claimed in claim 1, 2 or 3 wherein the substance used as solvent in stage (2) is a ketone, an acetate ester, an ether or an aromatic compound.
6. The process as claimed in claim 1, 2 or 3 wherein the resin solution in stage (2) is cooled to a temperature ? 50°C.
7. The process as claimed in claim 1, 2 or 3 wherein the solvent is removed in vacuo at a temperature below 65°C after preparation of the aqueous dispersion.
8. The process as claimed in claim 1, 2 or 3 wherein the reaction between the polyepoxide and the compound which contains one or more hydroxyl groups is carried out at a temperature of from 100 to 180°C and in the presence of a compound containing basic nitrogen as catalyst.
9. The process as claimed in claim 1, 2 or 3 wherein the compound reacted with the polyepoxide has two hydroxyl groups.
10. An electro-coating paint capable of being cathodically deposited on an electrically conductive substrate and heat-curable at a temperature below 160°C with a baking time not ex-ceeding 30 minutes, which paint contains an aqueous dispersion obtained by a process as claimed in claim 1.
11. A process of painting an electrically conductive sub-strate which comprises cathodically depositing on the electrically conductive substrate an electro-coating paint as claimed in claim 10 and then subjecting the deposited paint coating to heat-curing at a temperature below 160°C with a baking time not exceeding 30 minutes.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3738220.9 | 1987-11-11 | ||
| DE19873738220 DE3738220A1 (en) | 1987-11-11 | 1987-11-11 | METHOD FOR PRODUCING CATHODICALLY DEPOSITABLE BINDER DISPERSIONS WITH CROSSLINKERS ON THE BASIS OF POLYISOCYANATES CAPACED WITH AMINO GROUPS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1329291C true CA1329291C (en) | 1994-05-03 |
Family
ID=6340237
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000582703A Expired - Lifetime CA1329291C (en) | 1987-11-11 | 1988-11-10 | Process for the preparation of binder dispersions capable of being cathodically deposited using crosslinking agents based on polyisocyanates blocked by amino groups |
Country Status (8)
| Country | Link |
|---|---|
| EP (2) | EP0319703B1 (en) |
| JP (1) | JPH0710961B2 (en) |
| AT (1) | ATE76423T1 (en) |
| BR (1) | BR8807784A (en) |
| CA (1) | CA1329291C (en) |
| DE (2) | DE3738220A1 (en) |
| ES (1) | ES2031571T3 (en) |
| WO (1) | WO1989004352A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6248225B1 (en) | 1998-05-26 | 2001-06-19 | Ppg Industries Ohio, Inc. | Process for forming a two-coat electrodeposited composite coating the composite coating and chip resistant electrodeposited coating composition |
| US6423425B1 (en) | 1998-05-26 | 2002-07-23 | Ppg Industries Ohio, Inc. | Article having a chip-resistant electrodeposited coating and a process for forming an electrodeposited coating |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2128843C (en) * | 1993-07-30 | 1997-10-07 | Susumu Midogohchi | Electrodepositable coating composition |
| DE19703869A1 (en) | 1997-02-03 | 1998-08-06 | Basf Coatings Ag | Aqueous binder dispersion for cationic electrocoating paints |
| DE19835703C1 (en) * | 1998-08-07 | 1999-05-20 | Bayer Ag | N,N'-disubstituted N-(2-hydroxyalkyl)urea |
| DE10236350A1 (en) | 2002-08-08 | 2004-02-19 | Basf Coatings Ag | Bismuth compound-containing electrophoretic coating composition comprises a crosslinking binding agent having (potential) cationic or anionic groups and bismuth sub-salicylate |
| US20060106188A1 (en) * | 2004-11-15 | 2006-05-18 | Ulrich Hermann | Thermally curable coating compositions |
| DE102007038824A1 (en) | 2007-08-16 | 2009-02-19 | Basf Coatings Ag | Use of bismuth subnitrate in electrodeposition paints |
| DE102008016220A1 (en) | 2008-03-27 | 2009-10-01 | Basf Coatings Ag | Electrocoating paints containing polymethyleneurea |
| JP2010254976A (en) * | 2009-03-30 | 2010-11-11 | Sanyo Chem Ind Ltd | Cationic electrodeposition coating composition |
| EP3083850B1 (en) | 2013-12-20 | 2019-02-06 | BASF Coatings GmbH | Formulations containing pigment and filler |
| EP3854831A1 (en) | 2020-01-24 | 2021-07-28 | BASF Coatings GmbH | Compound comprising fully blocked isocyanate and silane groups and its use as crosslinker in electrocoating materials |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU691787A1 (en) * | 1976-06-14 | 1979-10-15 | Украинское Отделение Всесоюзного Государственного Проектно-Изыскательского И Научно-Исследовательского Института Сельэнергопроект | Apparatus for measuring wear of power transformers |
| US4115328A (en) * | 1977-01-07 | 1978-09-19 | Ciba-Geigy Corporation | Process for making stable solvent-free, aqueous epoxy resin dispersions |
| DE3108073C2 (en) * | 1981-03-04 | 1983-10-06 | Basf Farben + Fasern Ag, 2000 Hamburg | Water-dispersible binders for cationic electrodeposition paints |
| JPS5840412A (en) * | 1981-09-04 | 1983-03-09 | Matsushita Electric Ind Co Ltd | Petroleum combustor |
| DE3311516A1 (en) * | 1983-03-30 | 1984-10-04 | Basf Farben + Fasern Ag, 2000 Hamburg | HEAT-CURABLE COATING AGENTS AND THEIR USE |
| DE3331903A1 (en) * | 1983-09-03 | 1985-03-21 | Basf Farben + Fasern Ag, 2000 Hamburg | WATER-DISPERSIBLE BINDING AGENTS FOR CATIONIC ELECTRO-DIP COATINGS AND METHOD FOR THEIR PRODUCTION |
-
1987
- 1987-11-11 DE DE19873738220 patent/DE3738220A1/en not_active Withdrawn
-
1988
- 1988-11-02 DE DE8888118215T patent/DE3871349D1/en not_active Expired - Lifetime
- 1988-11-02 ES ES198888118215T patent/ES2031571T3/en not_active Expired - Lifetime
- 1988-11-02 EP EP19880118215 patent/EP0319703B1/en not_active Expired - Lifetime
- 1988-11-02 WO PCT/EP1988/000994 patent/WO1989004352A1/en not_active Application Discontinuation
- 1988-11-02 AT AT88118215T patent/ATE76423T1/en not_active IP Right Cessation
- 1988-11-02 BR BR888807784A patent/BR8807784A/en not_active IP Right Cessation
- 1988-11-02 JP JP1500715A patent/JPH0710961B2/en not_active Expired - Lifetime
- 1988-11-02 EP EP19890900806 patent/EP0386150A1/en active Pending
- 1988-11-10 CA CA000582703A patent/CA1329291C/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6248225B1 (en) | 1998-05-26 | 2001-06-19 | Ppg Industries Ohio, Inc. | Process for forming a two-coat electrodeposited composite coating the composite coating and chip resistant electrodeposited coating composition |
| US6423425B1 (en) | 1998-05-26 | 2002-07-23 | Ppg Industries Ohio, Inc. | Article having a chip-resistant electrodeposited coating and a process for forming an electrodeposited coating |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0319703A1 (en) | 1989-06-14 |
| EP0319703B1 (en) | 1992-05-20 |
| ATE76423T1 (en) | 1992-06-15 |
| EP0386150A1 (en) | 1990-09-12 |
| ES2031571T3 (en) | 1992-12-16 |
| BR8807784A (en) | 1990-10-16 |
| JPH03500057A (en) | 1991-01-10 |
| JPH0710961B2 (en) | 1995-02-08 |
| DE3871349D1 (en) | 1992-06-25 |
| WO1989004352A1 (en) | 1989-05-18 |
| DE3738220A1 (en) | 1989-05-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |
Effective date: 20110503 |