CA2007934A1 - Heat-curable coating composition for cathodic electrocoating - Google Patents
Heat-curable coating composition for cathodic electrocoatingInfo
- Publication number
- CA2007934A1 CA2007934A1 CA002007934A CA2007934A CA2007934A1 CA 2007934 A1 CA2007934 A1 CA 2007934A1 CA 002007934 A CA002007934 A CA 002007934A CA 2007934 A CA2007934 A CA 2007934A CA 2007934 A1 CA2007934 A1 CA 2007934A1
- Authority
- CA
- Canada
- Prior art keywords
- coating composition
- groups
- crosslinking agent
- water
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- 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
- C09D5/4488—Cathodic paints
Abstract
- 19 - O.Z. 0062/02081 Abstract of the Disclosure: A heat-curable, cathodically depositable aqueous electrocoating composition contains (A) from 50 to 95% by weight of a polymerization or polycondensation or polyaddition product which has an average molecular weight of from 200 to 20,000 and primary and/or secondary hydroxyl groups and primary, secondary and/or tertiary amino groups and is water-thinnable on protonation with an acid, and (B) from 5 to 50% by weight of a water-thinnable cross-linking agent having cationic groups or group which are convertible into cationic groups by protonation with an acid.
Description
2(~)793~
O.Z. 0062/02081 Heat-curable coating composition for cathodic electrocoating ~ = .
The present invention relates to a cathodic elec-S trocoating composition which contains an organicsynthetic resin component which becomes water-thinnable on protona-tion with an acid, a water-thinnable crosslinking agent, optional pigments, fillers and coating auxiiiaries, and in an amount of up to 20% by weight, based on the total weight of the coating composition, an organic solvent.
Most ~f the present-day electrocoating composi-tions of high throwing power and good corrosion protec-tion comprise amino-epoxy resins as described for example in DE-A-3,422,457, ~E-A-3,325,061 and DE-A-3,444,110.
This epoxy re~in is usually admixed with a crosslinking agent in organic solution, and the mixture is then protonated and dispersed in water. After deposition on metal the binder i8 thermally crosslinked by baking at from 160 to 200C.
A disadvantage of this technique of preparing an electrocoating composition lies in the strictnes~ of con-ditions which must be adhered to. The binder is custo-marily prepared at elevated temperature, in general at up to 120C, and i8 mixed immediately thereafter, as it c0018 down but while still hot, with the crosslinking agent before being disper~ed in water. Consequently, there is a danger of a premature reaction between the binder and the crosslinking agent, in particular if, owing to produc-tion difficulties, the mixture is kept in the reactor at for example 50 - 70C for a prolonged period. For this rea~on, the binder is cooled down to such an extent that such a reaction takes place only to a minor extent.
However, this means a very long cooling-down period in practice. Furtharmore, the time between the mixing and the dispersing i8 kept to a minimum, but again this i~
not always pos~ible for production reasons, 80 that in practice there may be variations from batch to batch.
:
2(~93~
; . .
- 2 - o.Z. 0062/02081 A further disadvantage of the abovementioned technique is the limited ~cope for varying the electro-coating compo~ition. The amount of crosslinking agent has a bearing for example on such important properties of the film as crosslinking den~ity, hardness and brittleness of the baked coat, solvent resistance and corrosion resis-tance, to name but a few. Similarly, the nature of the crosslinking agent has a bearing on many properties.
However, the addition of a crosslinking agent to the binder prior to dispersing fixes the mixing ratio and the nature of the crosslinking agent from the ~tart. If any ingredient or mixing ratio i8 to be changed, it is necessary to start again from scratch.
A further constraint on the abovementioned procedure concerns the baking temperatures. Baking temperatures within the range from 160 to 200C are unfavorable in principle. For a start, the energy requirements are very high at such high temperature~, since the entire car body must be heated to this tempera-ture. In addition, most crosslinking agents based onaromatic isocyanates, in particular on toluylene diiso-cyanate, are very prone to yellowing at such tempera-tures, and the danger i~ that this yellowing will also be visible in the topcoat. Furthermore, car bodies increas-ingly incorporate plastics components whose dimensionalstability is no longer ensured at such high temperatures.
There has therefore been no shortage of attempts to lower the baking temperature of electrocoatings.
EP-A-208,867 and EP-A-220,440 propose for this purpose isocyanate type crosslinking agents whose isocyanate groups are blocked via malonic ester groups. ~alonic ester groups are known blocking groups of low-bake characteristics, baking temperatures down to 120~C being obtainable therewith. In US 4,659,770, an acrylate binder which contains primary amino groups is mixed in organic solution with a crosslinking agent comprising an alipha-tic isocyanate whose isocyanate groups are blocked with :;
, 2(~ 33~
O.Z. 0062/02081 Heat-curable coating composition for cathodic electrocoating ~ = .
The present invention relates to a cathodic elec-S trocoating composition which contains an organicsynthetic resin component which becomes water-thinnable on protona-tion with an acid, a water-thinnable crosslinking agent, optional pigments, fillers and coating auxiiiaries, and in an amount of up to 20% by weight, based on the total weight of the coating composition, an organic solvent.
Most ~f the present-day electrocoating composi-tions of high throwing power and good corrosion protec-tion comprise amino-epoxy resins as described for example in DE-A-3,422,457, ~E-A-3,325,061 and DE-A-3,444,110.
This epoxy re~in is usually admixed with a crosslinking agent in organic solution, and the mixture is then protonated and dispersed in water. After deposition on metal the binder i8 thermally crosslinked by baking at from 160 to 200C.
A disadvantage of this technique of preparing an electrocoating composition lies in the strictnes~ of con-ditions which must be adhered to. The binder is custo-marily prepared at elevated temperature, in general at up to 120C, and i8 mixed immediately thereafter, as it c0018 down but while still hot, with the crosslinking agent before being disper~ed in water. Consequently, there is a danger of a premature reaction between the binder and the crosslinking agent, in particular if, owing to produc-tion difficulties, the mixture is kept in the reactor at for example 50 - 70C for a prolonged period. For this rea~on, the binder is cooled down to such an extent that such a reaction takes place only to a minor extent.
However, this means a very long cooling-down period in practice. Furtharmore, the time between the mixing and the dispersing i8 kept to a minimum, but again this i~
not always pos~ible for production reasons, 80 that in practice there may be variations from batch to batch.
:
2(~93~
; . .
- 2 - o.Z. 0062/02081 A further disadvantage of the abovementioned technique is the limited ~cope for varying the electro-coating compo~ition. The amount of crosslinking agent has a bearing for example on such important properties of the film as crosslinking den~ity, hardness and brittleness of the baked coat, solvent resistance and corrosion resis-tance, to name but a few. Similarly, the nature of the crosslinking agent has a bearing on many properties.
However, the addition of a crosslinking agent to the binder prior to dispersing fixes the mixing ratio and the nature of the crosslinking agent from the ~tart. If any ingredient or mixing ratio i8 to be changed, it is necessary to start again from scratch.
A further constraint on the abovementioned procedure concerns the baking temperatures. Baking temperatures within the range from 160 to 200C are unfavorable in principle. For a start, the energy requirements are very high at such high temperature~, since the entire car body must be heated to this tempera-ture. In addition, most crosslinking agents based onaromatic isocyanates, in particular on toluylene diiso-cyanate, are very prone to yellowing at such tempera-tures, and the danger i~ that this yellowing will also be visible in the topcoat. Furthermore, car bodies increas-ingly incorporate plastics components whose dimensionalstability is no longer ensured at such high temperatures.
There has therefore been no shortage of attempts to lower the baking temperature of electrocoatings.
EP-A-208,867 and EP-A-220,440 propose for this purpose isocyanate type crosslinking agents whose isocyanate groups are blocked via malonic ester groups. ~alonic ester groups are known blocking groups of low-bake characteristics, baking temperatures down to 120~C being obtainable therewith. In US 4,659,770, an acrylate binder which contains primary amino groups is mixed in organic solution with a crosslinking agent comprising an alipha-tic isocyanate whose isocyanate groups are blocked with :;
, 2(~ 33~
- 3 - O.Z. 0062/02081 ketoxime or malonic e~ter. Curing take~ place at 60 -90C. It i~ true that all these ~y~tem~ ~how low-bake characteri~tic~, but their storage life is limited. It is especially in electrocoating, where the aqueous di~per-~ion i~ ~tirred at about 30C for weeks during which no premature reaction must take place, that such combina~
tion~ are unusable.
DE-A-3,630,667 describes a process which avoids the abovementioned disadvantage In this process, first a binder i~ applied by electrocoating and then a free isocyanate is applied from organic solution as a ~eparate crosslinking agant. This proces~ i~ uneconomical and Lmpracticable. For a ~tart, large amounts of solvent are required for applying the crosslinking agent, for another an advantage of electrocoating is precisely that cavities and other areas not reachable by conventional application techniques can be covered. However, the crosslinking agent is unable to penetrate into these areas, 80 that curing cannot take place there.
There is therefore a demand for a process for preparing electrocoating compositions which are stable to storage at 30C but are curable at relatively low tem-perature~, for example at 120 - 140~C.
Water-soluble or water-dispersible blocked isocyanate~ are known. For instance, US 4,098,933 des-cribes water-soluble or water-dispersible blocked i~o-cyanates obtained by reaction of isocyanates with com-pounds containing carboxyl groups, sulfonic acid groups, tertiary amines, quaternary ammonium groups or polyalkyl-ene oxidQs. These watar-soluble or water-dispersible blocked isocyanate~ are used in aqueous solution together with organic compounds having at least two hydrogen atoms reactive towards isocyanate for manufacturing sheetlike materials. There is no mention here that thes~ isocyan-ates would be suitable for use as crosslinking agents for the binders in cathodic electrocoating compositions.
It i8 an ob~ect of the present invention to 2~ia793~
tion~ are unusable.
DE-A-3,630,667 describes a process which avoids the abovementioned disadvantage In this process, first a binder i~ applied by electrocoating and then a free isocyanate is applied from organic solution as a ~eparate crosslinking agant. This proces~ i~ uneconomical and Lmpracticable. For a ~tart, large amounts of solvent are required for applying the crosslinking agent, for another an advantage of electrocoating is precisely that cavities and other areas not reachable by conventional application techniques can be covered. However, the crosslinking agent is unable to penetrate into these areas, 80 that curing cannot take place there.
There is therefore a demand for a process for preparing electrocoating compositions which are stable to storage at 30C but are curable at relatively low tem-perature~, for example at 120 - 140~C.
Water-soluble or water-dispersible blocked isocyanate~ are known. For instance, US 4,098,933 des-cribes water-soluble or water-dispersible blocked i~o-cyanates obtained by reaction of isocyanates with com-pounds containing carboxyl groups, sulfonic acid groups, tertiary amines, quaternary ammonium groups or polyalkyl-ene oxidQs. These watar-soluble or water-dispersible blocked isocyanate~ are used in aqueous solution together with organic compounds having at least two hydrogen atoms reactive towards isocyanate for manufacturing sheetlike materials. There is no mention here that thes~ isocyan-ates would be suitable for use as crosslinking agents for the binders in cathodic electrocoating compositions.
It i8 an ob~ect of the present invention to 2~ia793~
- 4 - O.Z. 0062/02081 develop electrocoating baths which are stable to ~torage over weeks but which, after deposition, are capable of curing at low temperatures within a short time. It is another object of the present invention to develop a process which is more reliable than exi~ting proces~e~
and help~ to avoid faulty batche~. It is a further ob~ect of the present invention to provide a process which permit~ variation~ in the makeup of the electrocoating compo~ition in the ready-produced bath.
We have found that these ob~ect~ are achieved by a heat-curable, cathodically depo~itable aqueous electro-coating compo~ition containing (A) from 50 to 95~ by weight of a polymerization or polycondensation or polyaddition product which has an average molecular weight of from 200 to 20,000 and primary and/or secondary hydroxyl groups and primary, secondary and~or tertiary amino groups and is water-thinnable on protonation with an acid, and (B) from S to 50% by weight of a water-thinnable cro~-linking agent having cationic groups or groups which are convertible into cationic groups by protonation with an acid.
There now follow detailed observations concerning the formative components of the coating composition:
Component (A) can be any art recognized ~ynthetic resin binder which contains primary and/or secondary hydroxyl groups and primary, secondary and/or tertiary amino groups and has an average molecular weight of from 200 to 20,000, such as an aminoepoxy resin, aminopoly-(meth)acrylate resin or aminopolyurethane re~in having an amine number of from 30 to 150. The u~e of aminoepoxy re~ins is preferred for basecoats intended to confer a high level of corrosion protection. The synthetic resin binder contains at least one amino group per molecule.
The lower l~mit of the amine number hould be 45, prefer-ably 70, and the upper limit should be 120, preferably 100. Example4 of aminoepoxy resins are reaction products - : . Z0~793~
and help~ to avoid faulty batche~. It is a further ob~ect of the present invention to provide a process which permit~ variation~ in the makeup of the electrocoating compo~ition in the ready-produced bath.
We have found that these ob~ect~ are achieved by a heat-curable, cathodically depo~itable aqueous electro-coating compo~ition containing (A) from 50 to 95~ by weight of a polymerization or polycondensation or polyaddition product which has an average molecular weight of from 200 to 20,000 and primary and/or secondary hydroxyl groups and primary, secondary and~or tertiary amino groups and is water-thinnable on protonation with an acid, and (B) from S to 50% by weight of a water-thinnable cro~-linking agent having cationic groups or groups which are convertible into cationic groups by protonation with an acid.
There now follow detailed observations concerning the formative components of the coating composition:
Component (A) can be any art recognized ~ynthetic resin binder which contains primary and/or secondary hydroxyl groups and primary, secondary and/or tertiary amino groups and has an average molecular weight of from 200 to 20,000, such as an aminoepoxy resin, aminopoly-(meth)acrylate resin or aminopolyurethane re~in having an amine number of from 30 to 150. The u~e of aminoepoxy re~ins is preferred for basecoats intended to confer a high level of corrosion protection. The synthetic resin binder contains at least one amino group per molecule.
The lower l~mit of the amine number hould be 45, prefer-ably 70, and the upper limit should be 120, preferably 100. Example4 of aminoepoxy resins are reaction products - : . Z0~793~
- 5 - O.Z. 0062/02081 of epoxy-containing resins having preferably terminal epoxy groups with saturated and~or unsaturated secondary and/or primary amines or aminoalcohols. These reaction products can be modified at the alkyl moiety by at least one primary and/or secondary hydroxyl group, by a mono-or dialkylamino group and/or by a primary amino group which i9 at least temporarily protected by ketiminiza-tion.
The epoxy re~ins used can be any desiredmaterials provided they have an average molecular weight of from 300 to 6000 and contain on average from 1.0 to 3.0 epoxy groups per molecule, preferably compounds having two epoxy group~ per molecule. Preference is given to epoxy resins having average molecular weights of from 350 to 5000, in particular from 350 to 2000. Particularly preferred epoxy resins are for example glycidyl ethers of polyphenols which on average contain at least twophenolic hydroxyl groups in the molecule and which are preparable ~ in a conventional manner by etherification with an epihalohydrin in the presence of alkali. Aromatic poly-epoxies having a higher epoxy equivalent weight can be prepared from tho~e having a lower epoxy equivalent weight and polyphenols.
The amino groups can be introduced in a conven-tional reaction as known to those skilled in the art andas described for example in EP 134,983, EP 165,556 and EP 166,314.
Component (A) i8 used in an amount of from 50 to 95% by weight, preferably from 60 to 80~ by weight, based on the total amount of components (A) and (B).
Suitable starting compounds for preparing the crosslinking agent (B) are for example amino resins such as urea-formaldehyde resins, melamine resins or benzo-guanamine resins, blocked isocyanate type cros~linking agents, cros~linkin~ agents which cure by esteraminolysis and/or transesterification, eg. ~-hydroxyalkyl ester type crosslinking agents as described in EP 40,867 and -. - "
..
. , Z(~1~1793~
The epoxy re~ins used can be any desiredmaterials provided they have an average molecular weight of from 300 to 6000 and contain on average from 1.0 to 3.0 epoxy groups per molecule, preferably compounds having two epoxy group~ per molecule. Preference is given to epoxy resins having average molecular weights of from 350 to 5000, in particular from 350 to 2000. Particularly preferred epoxy resins are for example glycidyl ethers of polyphenols which on average contain at least twophenolic hydroxyl groups in the molecule and which are preparable ~ in a conventional manner by etherification with an epihalohydrin in the presence of alkali. Aromatic poly-epoxies having a higher epoxy equivalent weight can be prepared from tho~e having a lower epoxy equivalent weight and polyphenols.
The amino groups can be introduced in a conven-tional reaction as known to those skilled in the art andas described for example in EP 134,983, EP 165,556 and EP 166,314.
Component (A) i8 used in an amount of from 50 to 95% by weight, preferably from 60 to 80~ by weight, based on the total amount of components (A) and (B).
Suitable starting compounds for preparing the crosslinking agent (B) are for example amino resins such as urea-formaldehyde resins, melamine resins or benzo-guanamine resins, blocked isocyanate type cros~linking agents, cros~linkin~ agents which cure by esteraminolysis and/or transesterification, eg. ~-hydroxyalkyl ester type crosslinking agents as described in EP 40,867 and -. - "
..
. , Z(~1~1793~
- 6 - O.Z. 0062/02081 carbalkoxymethyl ester type crosslinking agents as described in DE 3,233,139. Further possible crosslinking agent~ are phenolic Mannich base~ a~ de~cribed for example in DE 3,422,457.
These crosslinking agent~, however, cannot be uqed unmodified, since they are not di~persible them-~elves. For thi~ reason, suitable modifying group~ mu~t be incorporated to en~ure disper~ibility. Such groups are for example tertiary amino groups via which, following protonation with an acid, a crosslinking agent becomes water-dispersible. It is also possible to u3e quaternary ammonium groups to ensure di~persibility.
Further pos~ible groups are compounds having quaternary phosphonium groups and tertiary sulfonium groups.
The tertiary amino group~ or quaternary ammonium group~ can be incorporated in various ways. It is poscible to ~tart for example from polyols which contain tertiary amino groups, and react these polyols with half-blocked diisocyanate~. Equally, the conversQ procedure i~ pos-sible, namely to react a diisocyanate with a polyol which contains tertiary amino groups by essentially reacting only one isocyanate group per molecule and subsequently blocking the ~econd isocyanatQ group. Suitable polyols having tertiary amino groups are for example:trishydroxy-alkylamines such as triethanolamine, reaction products of amines with epoxie~ or alkyl halides. A further pos~lbility i8 the partial replacement of the isocyanate type blocking agent for compounds which contain tertiary amino group~. For instance, in a commercial crosslinking agent formed from a polyol and diisocyanate, from 50 to 90% of the free isocyanate groups can be blocke~. The remaining isocyanate groups are then reacted with an alcohol or amine which contains tertiary amino groups.
Suitable for this purposQ are for example dimethylamino-propylam$ne and dimethylaminopropanol. Diisocyanate~
which have been half-reacted with dL~ethylaminopropylamine 2 ~ 3 - - 7 - ~.Z. 0062/02081 or dimethylaminopropanol are also suitable for modifying OH-containing crosslinking agents such as, for example, phenolic Mannich bases in which some of the phenol groups can be converted by these isocyanates. Quaternary ammo-nium groups can be prepared by reacting tertiary amineswith alkyl halides or with epoxies. For instance, Epikote-828 (~rom SHELL) can be reacted with two moles of methyl-diethanolamine to obtain a hydroxyl-containing polyol suitable for the conversion of isocyanates.-I~ is also possible to block polyisocyanate~ with epoxide-containing compound~ and to quaternize the remaining epoxy groups with free tertiary amines.
To incorporate phosphonium structures, it is possible to start from phosphine-containing isocyanates which are converted to phr ~honium groups in a conven-tional manner. The preference here is for the reaction with monoepoxieY. This reaction can be carried out by first reacting a hydroxyl-containing phosphine with isocyanates and then quaternizing with monoepoxy; it is preferable, however, to react the i30cyanate with an epoxy-containing compound and then with free phosphine.
Suitable phosphines are for examplQ trialkylphosphines such as triethylphosphine, tributylpho~phine and tri-octylphosphine, triarylphosphines, for example triphenyl-phosphine, alkylarylphosphlnes and the like. Suitablehydroxyl-containing phosphine is for example tri~hydroxy-ethylphosphinQ.
The preparation of sulfonium-containing isocyan-ates can be carried out in a similar manner. Hydroxyl-containing sulfides can be reacted with isocyanates and then converted into the sulfonium salt in a conventional manner as described for example in Heuben-Weyl, vol. Ell (part 1), pp. 341 - 502. Furthermore, epoxy-containing isocyanates can be reacted with free sulfides. Suitable sulfides are dialkyl sulfides such as diethyl sulfide, dibutyl sulfide and higher sulfides, diaryl ~ulfides such as diph0nyl sulfidQ, hydroxyl-containing sulfides such as - : ,:: . :
. .:
':~ ., 2(~93~
- - 8 - O.Z. 0062/02081 ethylmercaptoethanol or thiodiglycol, etc.
In general, it is sufficient to modify only 10 -50%, preferably only 20 - 45%, of all cros~linking agent molecules to ensure adequate dispersibility.
Although the use of the novel cro~slinking aqents according to the present invention in the form of a di~persion is preferred, they can also be use~ in a conventional form. Thu~, the crosslinking aqent~ accord-ing to the present invention can be mixed with the binder in organic solution, partly neutralized and then dis-persed. Here too the crosslinking agents according to the present invention offer some advantages. Dispersions containing aromatic crosslinking agent tend to form a sediment of particles separated from the bath. Use of the crosslinking agents according to the present invention ubstantially reduces or completely eliminates any ~edimentation tendency. Furthermore, less solvent is nece~sary in general to obtain the desired flow proper-ties and the necessary layer thickness.
AR well as the abovementioned components it is possible to add further substances such a~ pigments, auxiliaries, solvents and curing catalysts. The coating compositions thus prepared can also be applied to sub-strates such as wood, plastic or metal by conventional methods. For use in cathodic electrocoating,the synthetic resin is converted in the presence of additives mentioned into a water-soluble form by protonation with an acid.
The acid usod is preferably a carboxylic acid such as formic acid, acetic acid or lactic acid, although an inorganic acid, for example a phosphoric acid, can also be used.
This di~persion is then mixed with a dispersion of the crosslinking agent added Ln the desired ratio. It i~ of course also possible to add the additives mentioned to the crosslinking agent and then to disperse the mixture.
For cathodic electrocoating, the solids content of the electrocoating bath is in general set to S - 30 by weight.
2(~ 3~
- 9 - O.Z. 0062/02081 Deposition customarily takes place at from 15 to 40C in the course of from 0.5 to 5 minutes and at a pH
of from 4.0 to 8.5, preferably a neutral pH, at a voltage of 50 to 500 V. In cathodic electrocoating, the electri-cally conducting object to be coated i~ connected as thecathode. The deposited film i~ cured at above 100C in the course of about 20 minutes.
EXAMPLES
Synthetic resin binder disper~ion In a vessel equipped with a water separator and a packed column, 12,440 g of hexamethylenediamine, 18,660 g of dimeric fatty acid (Pripol- 1013, from Uni-chema), 3,000 g of linseed oil fatty acid and 2,566 g of xylene were made to react. 1,150 g of water and 1,750 g of xylene were distilled off in the course of 3 - 4 hour3. The product had an amine number of 233 mg of ROH/g.
In a reaction ve~sel, 815 g of a diglycidyl ether of bi~(4-hydroxyphenyl)-2,2-propane (bisphenol A) and epichlorohydrin having an equivalent weight of 188, 214.4 g of bisphenol A and 53.6 g of propylene glycol monophenyl ether were madQ to react by mean3 of 0.26 g of triphenylphosphine. 3 hours' reaction at 130C gave a product having an epoxy equivalent weight of 4~9. It wa~
diluted with 302 g of i~obutanol and 212.4 g of toluene and cooled to 60C. 70.8 g of methylethanolamine and 351.6 g of the abovementioned intermediate were then added, the mixture was heated to 80C. 2 hours later, epoxy was no longer detectable. The synthetic resin had an amine numbor of 105 mg of ROH/g, a solid~ content of 70~ by weight and a plate/cone viscosity of 4,000 mPa~ at 75C.
137 g of the abovementioned synthe~ic re~in binder were treated with 3.1 g of acetic acid. Deionized water was then added with ~tirring to obtain a 353 strength by weight dispersion.
:~ :
2(~93~
- 10 - O.Z. 0062tO2081 Pigment pa~te 640 g of a diglycidyl ether based on bisphenol A
and epichlorohydrin having an epoxy equivalent weight of 485 and 160 g of such a diglycidyl ether having an epoxy equivalent weight of 189 were mixed at 100C. A further vessel was charged with 452 g of hexamethylenediamine, the contentY heated to 100C, and 720 g of the abDve hot epoxy resin mixture were added in the course of an hour during which slight cooling had to be applied in order to keep the temperature at 100C. After a further 30 min-utes, the excess hexamethylenediamine wa~ taken off by increasing the temperature and reducing the pressure, the final temperature being 205C and the final pressure 30 mbar. 57.6 g of stearic acid, 172.7 g of dimeric fatty acid and llS g of xylene were then added. The water formed was distilled off azeotropically at 175 - 180C in the course of 90 minutes. 58 g of butylglycol and 322 g of i~obutanol were then added. The product had a olid~
content of 70% by weight and a vi~co~ity, measured at 75C u~ing a plate/cone viscometer, of 2,240 mPas.
110 g of the synthetic resin thus obtained were ball-milled together with 36 g of ethylene glycol mono-butyl ether, 3 g of acetic acid, 170 g of titanium dioxide, 18 g of lead silicate, 4.5 g of carbon black and 170 g of water until the particle size was ~ 7 ~m.
Crosslinking agent 1 A reaction vessel was charged with 263.4 g of toluylene diisocyanate, 85.2 g of toluene, 85.2 g of methyl isobutyl ketone and 0.15 g of dibutyltin dilaurate.
67 g of trimethylolpropane in 57 g of 1:1 toluene/methyl isobutyl ketone were then added dropwise in the course of an hour, the mixture was stirred at 20 - 25C for 1 hour.
Thereafter a mixture of 108.7 g of methyl ethyl ketoxime and 25.6 g of dimethylaminopropylamine was added, and the contents were ~tirred at 30 - 40C.
Crosslinking agent 2 ~he procedure was as for cro~slinking agent 1, 2(~793~
- 11 - O.Z. 0062/02081 except that the stated amount of blocking agent was changed to 117.5 g of methyl ethyl ketoxLme and 15.3 g of dLmethylaminopropylamine.
Crosslinking agent 3 The procedure wa~ a~ for cro~slinking agent 1, except that the methyl ethyl ketoxime was replaced by 143.75 g of methyl isobutyl ketoxLme.
Crosslinking agent 4 A reaction vessel was charged with 333.3 g of i~ophorone diisocyanate, 185 g of toluene, 185 g of methyl ethyl ketone and 0.15 g of dibutyltin dilaurate.
67 g of trimethylolpropane and 64 g of 1 : 1 toluene/
methyl ethyl ~etone were added dropwise in the course of an hour, and the contents were subsequen~ly stirred at 20C for one hour. Thereafter a mixture of 152.8 g of 2,6-dimethylpiperidine and 15.33 g of dimethylaminopro- -pylamine was added, and the contents were subsequently tirred until the isocyanate value had dropped to zero.
Crosslinking agent 5 The procedure was as for cros~linking agent 3, except that the dimethylaminopropylamine wa~ replaced by 25.8 g of dimethylaminopropanol.
Crosslinking agent 6 The procedure was as for crosslinking agent 1, except that the blocking agent used this time was 142.1 g of dibutylamine and 40.9 g of dimethylaminopropylamine.
Crosslinking agent 7 152 g of bisphenol A, 63 g of a diglycidyl ether of bisphenal A having an epoxy equivalent weight of 189 and 0.1 g of tributylphosphine were heated at 160C for 1 hour. Epoxy was then no longer detectable, a chain-advanced diphenol having been formed. It wa admixed with 53.8 g of isopropanol, 129 g of di-n-butylamine, 31.5 g of paraformaldehyde and 17.6 g of isobutanol, the mixture was heated at 80C for 2 hour~. The product had a solids content of B0% by weight.
A reaction vessel was charged with 222.2 g of 20~7~3~
- 12 -- O.Z. 0062/02081 i~ophorone dii30cyanate, 94.1 g of toluene and 40.5 g of methyl i obutyl ketone. 102.2 g of dimethylaminopropyl-amine were added at 20 to 25C, and the contents were sub~equently stirred for 30 minutes.
143 g of this product were added to 509 g of the phenolic Mannich typa cros~linking agent prepared in stage 1. Stirring was continued at 50C until the i80-cyanate value had dropped to zero.
Crosslinking agent 8 A reaction ves~el was charged with 222.2 g of isophorone diisocyanate, 94.1 g of toluene and 40.5 g of methyl isobutyl ketone. 103.2 g of dimetAylaminopropanol were added at 20 - 25C, and the contents were subse-quently ~tirred for 30 minutes.
143 g of this product were added to 509 g of the phenolic Mannich type cros~linking agent prepared in stage 1 of crosslinking agent 8. Stirring was continued at 50C until the isocyanate value had dropped to zero.
Crosslinking agent 9 A reaction vessel was charged with 174 g of toluylene diisocyanate, 94.1 g of toluene and 40.5 g of methyl isobutyl ketone. 103.2 g of dimethylaminopropanol were added at 20 - 25C, and the contents were subse-quently stirred for 30 minutes.
124 g of this product were added to 509 g of the phenolic Nannich type crosslinking agent prepared in stage 1 of crosslinking agent 8. Stirring was continued at 50 9C until the isocyanate value had dropped to zero.
Crosslinking agent 10 A reaction vessel wa8 charged with 375 g of diphenylmethane diisocyanate, 76 g of trimethylolpropane and 465 g of ethylglycol acetate. The content~ ware stirred at 50C until the NC0 content had dropped to the theore-tical value. Thereafter 168 g of dibutylamine and 20.6 g of dimethylaminopropanol were added, and the contents were stirred at 50C for 2 hours. Thereafter a mixture of 9 g of glacial acetic acid, 27 g of water and 12.2 g of ':
2~ 7~3 - 13 - O.Z. 0062/02081 glycide was added, and 60C was maintained for 3 hour3.
Cro~slinking agent 11 A reaction vessel was charged with 375 ~ of diphenylmethane diisocyanate, 76 g of trimethylolpropane S and 300 g of ethylglycol acetate. The contents were stirred at 60C until the NCO content had dropped to the theoretical value. ~hereafter 174.4 g of dibutylamine and 16 g of ethylthioethanol were added at 60C, and the contents were stirred for 2 hour~. After 166 g of butyl-glycol, 6 g of glacial acetic acid, 18 g of water and11.1 g of glycide had been added, the content~ were stirred at 60C for a further 3 hours.
Crosslinking agent 12 A reaction ves~el wa~ charged with 86 g of phenyl glycide ether in 100 g of isopropanol, followed at 70C
by a mixture of 61 g of thiodiglycol, 30 g of glacial acetic acid and 18 g of water. Ths contents were stirred at 70C for 4 hour~. This solution was added to 812 g of a 70% strength by weight solution of a diphenylmethane diisocyanate which had been half-blocked with dibutyl-amine, and the contents were stirred at 60C for 4 hour~.
Crosslinking agent 13 A reaction vessel was charged with 375 g of diphenylmethane diisocyanate, 76 g of trimethylolpropane 2S and 166 g of ethylglycol acetate. Stirring was continued at 50C until the NCO content had dropped to the theo-reti~al value. Thereafter 155 g of dibutylamine were added, and the contents were subsequently stirred for 30 minutes. 22.2 g of glycide were then added, and the contents were stirred at 50C for 3 hours.
This intermQdiate was then mixed with 60.6 g of tributyl phosphine, 18 g of glacial acetic acid and 54 g of water, and the contents were stirred at 50C for 2 hours.
Crosslinking agent 14 The intermediate for crosslinking agent 13 was used, but it was mixed with 30.3 g of triethylamine, 18 Z0~79 - 14 - O.Z. 0062/02081 of glacial acetic acid and 36 g of water.
Crosslinking agent 15 The intermediate for crosslinking agent 13 was used, but it was mixed with 38.3 g of thiodiglycol, 108 g of water and 18 g of glacial acetic acid.
Crosslinking aqent dispersion 1 686.7 g of crosqlinking agent 1, having a -qolid~
content of 60% by weight, were treated with 8.1 g of acetic acid. Thereafter 505.5 g of water were added a little at a time with stirring. A mixture of 300 g of ~olvent/water was then distilled off under reduced pressure at 40 - 50C while 300 g of water were added.
The re~ult obtained wa~ a finely divided, stable disper-sion.
Cro~linking agent dispersion 2 The procedure was as for diQpersion 1, but 6.3 g of acetic acid were used.
Crosslinking agent dispersion 3 The procedure was as for disper~ion 1, again affording a stable, finely divided dispersion.
Cros~linking agent dispersion 4 343.3 g of crosslinking agent 4, having a ~olid~
content of 60% by weight, were treated with 4.74 g of acetic acid. Thereafter 245.2 g of water were added a little at a time with stirring. The result obtained was a finely divided dispersion.
Croaslinking agent dispersion 5 The procedure was a~ for dispersion 4, except that 5.3 g of acetic acid were added.
Crosslinking agent dispersion 6 The procedure was as for dispersion 1, likewi~e affording a stable, finely divided dispersion.
Cro~slinking agent dispersion 7 294 g of crosslinking agent 7, having a solid3 content of 70% by weight, were mixed with 29.4 g of isobutanol. Thereafter 7.4 g of acetic acid were added, and the mixture was dispersed with 265 g of water by 2 ~ ~ 7 ~3 - 15 - O.Z. 0062/02081 Qtirring. Thereafter, while 100 g of water were added, a mixture of ~olvent and wat~r (200 g) wa~ di~tilled off under reduced pres~ure. The result obtained was a finely divided stable, readily filterahle dispersion.
Cro~slinking agent disper~ion 8 The procedure was as for cros31inking agent dispersion 7, except that cro~slinking agent 8 wa used.
Crosslinking agent disp~rsion 9 294 g of crosslinking agent 9, having a solids con-tent of 70% by weight, were mixed with 60 g of isobutanol.
4.5 g of glacial acetic acid were added, and the mixture was dispersed with 265 g of water while stirring. The re~ult obtained wa~ a finely divided, stable dispersion.
Crosslinking aqent dispersion 10 1,130 g of cros~linking agent 10 were mixed with 56 g of butylglycol and di~per~ed in 894 g of water.
Thereafter 400 g of solvent/water mixture were distilled off under reduced pres~ure.
Electrocoating bath 1 1,061.7 g of the binder dispersion, 775 g of the pigment paste and 926 g of crosslinking agent dispersion 4 were mixed and made up with water to a solids content of 20% by weight. Deposition at 300 V produced a coat 20 ~m in thickness. The coat was crosslinkable at a baking temperaturQ of 140C.
Electrocoating bath 2 The coating bath was made up in the same way as coating bath 1, except that cro3slinking agent dispersion 2 w~ used. Following the addition of 30 g of Napsol' PPH
(from SHELL) and aging for 7 days a deposition voltage of 300 V produced coats from 23 to 25 ~m in thickness. The deposited films were resi~tant to acetone after baking at 120C, showed excellent leveling and conferred outstand-ing corrosion protection.
Electrocoating bath 3 The procedure wa~ as for electrocoating bath 1 using the following ingredientss Z(:~21793~
- 16 - O.Z. 0062/02081 1,061.7 g of synthetic resin binder dispersion 775 g of pigment paste 902 g of cros~linking agent dispersion 1.
30 g/l of Napsol were added to the bath. After S aging for 7 days, deposition at 320 V produced a coat 18 ~m in thickne~s.
After baking at 120C for 20 minutes the film wa3 solvent-resistant, showed good leveling and conferred outstanding corrosion protection. The bath was stable over weeks, even then being free of sediment or coagulum.
Electrocoating bath 4 The procedure was as for coating bath 3, except that cros~linking agent dispersion 2 was used. After aging, deposition at 350 V gave a coat 19 ~m in thick-ness. After curing at 120C the film showed satisfactory leveling and solvent resistance.
Electrocoating bath 5 1,370 g of synthetic resin binder di~per-~ion, 775 g of pigment pa~te and 595 g of crosslinking agent dispersion 8 were used to prepare a bath as described under coating bath 1. Following addition of 20 g of Napsol PPH per 1 and aging for 7 days a deposition voltage of 280 V gave a coat 22 ~m in thickne~s which was solvent-resistant on baking at 140C. The properties of the bath were unchanged after 4 weekq' aging.
Electrocoating bath 6 Crosslinking agent dispersion 9 was used to preparo a bath a~ described under coating bath 5. Follow-ing addition of 25 g/l of Napsol PPH and aging for 7 days a deposition voltage of 300 V gave a coat of 23 ~m thick-ness which become solvent-resistant on baking at 140C.
After a further 4 weeks' aging, the bath was free of sediment or coagulum, and any films deposited therefrom were unchanged compared with the first deposited film.
These crosslinking agent~, however, cannot be uqed unmodified, since they are not di~persible them-~elves. For thi~ reason, suitable modifying group~ mu~t be incorporated to en~ure disper~ibility. Such groups are for example tertiary amino groups via which, following protonation with an acid, a crosslinking agent becomes water-dispersible. It is also possible to u3e quaternary ammonium groups to ensure di~persibility.
Further pos~ible groups are compounds having quaternary phosphonium groups and tertiary sulfonium groups.
The tertiary amino group~ or quaternary ammonium group~ can be incorporated in various ways. It is poscible to ~tart for example from polyols which contain tertiary amino groups, and react these polyols with half-blocked diisocyanate~. Equally, the conversQ procedure i~ pos-sible, namely to react a diisocyanate with a polyol which contains tertiary amino groups by essentially reacting only one isocyanate group per molecule and subsequently blocking the ~econd isocyanatQ group. Suitable polyols having tertiary amino groups are for example:trishydroxy-alkylamines such as triethanolamine, reaction products of amines with epoxie~ or alkyl halides. A further pos~lbility i8 the partial replacement of the isocyanate type blocking agent for compounds which contain tertiary amino group~. For instance, in a commercial crosslinking agent formed from a polyol and diisocyanate, from 50 to 90% of the free isocyanate groups can be blocke~. The remaining isocyanate groups are then reacted with an alcohol or amine which contains tertiary amino groups.
Suitable for this purposQ are for example dimethylamino-propylam$ne and dimethylaminopropanol. Diisocyanate~
which have been half-reacted with dL~ethylaminopropylamine 2 ~ 3 - - 7 - ~.Z. 0062/02081 or dimethylaminopropanol are also suitable for modifying OH-containing crosslinking agents such as, for example, phenolic Mannich bases in which some of the phenol groups can be converted by these isocyanates. Quaternary ammo-nium groups can be prepared by reacting tertiary amineswith alkyl halides or with epoxies. For instance, Epikote-828 (~rom SHELL) can be reacted with two moles of methyl-diethanolamine to obtain a hydroxyl-containing polyol suitable for the conversion of isocyanates.-I~ is also possible to block polyisocyanate~ with epoxide-containing compound~ and to quaternize the remaining epoxy groups with free tertiary amines.
To incorporate phosphonium structures, it is possible to start from phosphine-containing isocyanates which are converted to phr ~honium groups in a conven-tional manner. The preference here is for the reaction with monoepoxieY. This reaction can be carried out by first reacting a hydroxyl-containing phosphine with isocyanates and then quaternizing with monoepoxy; it is preferable, however, to react the i30cyanate with an epoxy-containing compound and then with free phosphine.
Suitable phosphines are for examplQ trialkylphosphines such as triethylphosphine, tributylpho~phine and tri-octylphosphine, triarylphosphines, for example triphenyl-phosphine, alkylarylphosphlnes and the like. Suitablehydroxyl-containing phosphine is for example tri~hydroxy-ethylphosphinQ.
The preparation of sulfonium-containing isocyan-ates can be carried out in a similar manner. Hydroxyl-containing sulfides can be reacted with isocyanates and then converted into the sulfonium salt in a conventional manner as described for example in Heuben-Weyl, vol. Ell (part 1), pp. 341 - 502. Furthermore, epoxy-containing isocyanates can be reacted with free sulfides. Suitable sulfides are dialkyl sulfides such as diethyl sulfide, dibutyl sulfide and higher sulfides, diaryl ~ulfides such as diph0nyl sulfidQ, hydroxyl-containing sulfides such as - : ,:: . :
. .:
':~ ., 2(~93~
- - 8 - O.Z. 0062/02081 ethylmercaptoethanol or thiodiglycol, etc.
In general, it is sufficient to modify only 10 -50%, preferably only 20 - 45%, of all cros~linking agent molecules to ensure adequate dispersibility.
Although the use of the novel cro~slinking aqents according to the present invention in the form of a di~persion is preferred, they can also be use~ in a conventional form. Thu~, the crosslinking aqent~ accord-ing to the present invention can be mixed with the binder in organic solution, partly neutralized and then dis-persed. Here too the crosslinking agents according to the present invention offer some advantages. Dispersions containing aromatic crosslinking agent tend to form a sediment of particles separated from the bath. Use of the crosslinking agents according to the present invention ubstantially reduces or completely eliminates any ~edimentation tendency. Furthermore, less solvent is nece~sary in general to obtain the desired flow proper-ties and the necessary layer thickness.
AR well as the abovementioned components it is possible to add further substances such a~ pigments, auxiliaries, solvents and curing catalysts. The coating compositions thus prepared can also be applied to sub-strates such as wood, plastic or metal by conventional methods. For use in cathodic electrocoating,the synthetic resin is converted in the presence of additives mentioned into a water-soluble form by protonation with an acid.
The acid usod is preferably a carboxylic acid such as formic acid, acetic acid or lactic acid, although an inorganic acid, for example a phosphoric acid, can also be used.
This di~persion is then mixed with a dispersion of the crosslinking agent added Ln the desired ratio. It i~ of course also possible to add the additives mentioned to the crosslinking agent and then to disperse the mixture.
For cathodic electrocoating, the solids content of the electrocoating bath is in general set to S - 30 by weight.
2(~ 3~
- 9 - O.Z. 0062/02081 Deposition customarily takes place at from 15 to 40C in the course of from 0.5 to 5 minutes and at a pH
of from 4.0 to 8.5, preferably a neutral pH, at a voltage of 50 to 500 V. In cathodic electrocoating, the electri-cally conducting object to be coated i~ connected as thecathode. The deposited film i~ cured at above 100C in the course of about 20 minutes.
EXAMPLES
Synthetic resin binder disper~ion In a vessel equipped with a water separator and a packed column, 12,440 g of hexamethylenediamine, 18,660 g of dimeric fatty acid (Pripol- 1013, from Uni-chema), 3,000 g of linseed oil fatty acid and 2,566 g of xylene were made to react. 1,150 g of water and 1,750 g of xylene were distilled off in the course of 3 - 4 hour3. The product had an amine number of 233 mg of ROH/g.
In a reaction ve~sel, 815 g of a diglycidyl ether of bi~(4-hydroxyphenyl)-2,2-propane (bisphenol A) and epichlorohydrin having an equivalent weight of 188, 214.4 g of bisphenol A and 53.6 g of propylene glycol monophenyl ether were madQ to react by mean3 of 0.26 g of triphenylphosphine. 3 hours' reaction at 130C gave a product having an epoxy equivalent weight of 4~9. It wa~
diluted with 302 g of i~obutanol and 212.4 g of toluene and cooled to 60C. 70.8 g of methylethanolamine and 351.6 g of the abovementioned intermediate were then added, the mixture was heated to 80C. 2 hours later, epoxy was no longer detectable. The synthetic resin had an amine numbor of 105 mg of ROH/g, a solid~ content of 70~ by weight and a plate/cone viscosity of 4,000 mPa~ at 75C.
137 g of the abovementioned synthe~ic re~in binder were treated with 3.1 g of acetic acid. Deionized water was then added with ~tirring to obtain a 353 strength by weight dispersion.
:~ :
2(~93~
- 10 - O.Z. 0062tO2081 Pigment pa~te 640 g of a diglycidyl ether based on bisphenol A
and epichlorohydrin having an epoxy equivalent weight of 485 and 160 g of such a diglycidyl ether having an epoxy equivalent weight of 189 were mixed at 100C. A further vessel was charged with 452 g of hexamethylenediamine, the contentY heated to 100C, and 720 g of the abDve hot epoxy resin mixture were added in the course of an hour during which slight cooling had to be applied in order to keep the temperature at 100C. After a further 30 min-utes, the excess hexamethylenediamine wa~ taken off by increasing the temperature and reducing the pressure, the final temperature being 205C and the final pressure 30 mbar. 57.6 g of stearic acid, 172.7 g of dimeric fatty acid and llS g of xylene were then added. The water formed was distilled off azeotropically at 175 - 180C in the course of 90 minutes. 58 g of butylglycol and 322 g of i~obutanol were then added. The product had a olid~
content of 70% by weight and a vi~co~ity, measured at 75C u~ing a plate/cone viscometer, of 2,240 mPas.
110 g of the synthetic resin thus obtained were ball-milled together with 36 g of ethylene glycol mono-butyl ether, 3 g of acetic acid, 170 g of titanium dioxide, 18 g of lead silicate, 4.5 g of carbon black and 170 g of water until the particle size was ~ 7 ~m.
Crosslinking agent 1 A reaction vessel was charged with 263.4 g of toluylene diisocyanate, 85.2 g of toluene, 85.2 g of methyl isobutyl ketone and 0.15 g of dibutyltin dilaurate.
67 g of trimethylolpropane in 57 g of 1:1 toluene/methyl isobutyl ketone were then added dropwise in the course of an hour, the mixture was stirred at 20 - 25C for 1 hour.
Thereafter a mixture of 108.7 g of methyl ethyl ketoxime and 25.6 g of dimethylaminopropylamine was added, and the contents were ~tirred at 30 - 40C.
Crosslinking agent 2 ~he procedure was as for cro~slinking agent 1, 2(~793~
- 11 - O.Z. 0062/02081 except that the stated amount of blocking agent was changed to 117.5 g of methyl ethyl ketoxLme and 15.3 g of dLmethylaminopropylamine.
Crosslinking agent 3 The procedure wa~ a~ for cro~slinking agent 1, except that the methyl ethyl ketoxime was replaced by 143.75 g of methyl isobutyl ketoxLme.
Crosslinking agent 4 A reaction vessel was charged with 333.3 g of i~ophorone diisocyanate, 185 g of toluene, 185 g of methyl ethyl ketone and 0.15 g of dibutyltin dilaurate.
67 g of trimethylolpropane and 64 g of 1 : 1 toluene/
methyl ethyl ~etone were added dropwise in the course of an hour, and the contents were subsequen~ly stirred at 20C for one hour. Thereafter a mixture of 152.8 g of 2,6-dimethylpiperidine and 15.33 g of dimethylaminopro- -pylamine was added, and the contents were subsequently tirred until the isocyanate value had dropped to zero.
Crosslinking agent 5 The procedure was as for cros~linking agent 3, except that the dimethylaminopropylamine wa~ replaced by 25.8 g of dimethylaminopropanol.
Crosslinking agent 6 The procedure was as for crosslinking agent 1, except that the blocking agent used this time was 142.1 g of dibutylamine and 40.9 g of dimethylaminopropylamine.
Crosslinking agent 7 152 g of bisphenol A, 63 g of a diglycidyl ether of bisphenal A having an epoxy equivalent weight of 189 and 0.1 g of tributylphosphine were heated at 160C for 1 hour. Epoxy was then no longer detectable, a chain-advanced diphenol having been formed. It wa admixed with 53.8 g of isopropanol, 129 g of di-n-butylamine, 31.5 g of paraformaldehyde and 17.6 g of isobutanol, the mixture was heated at 80C for 2 hour~. The product had a solids content of B0% by weight.
A reaction vessel was charged with 222.2 g of 20~7~3~
- 12 -- O.Z. 0062/02081 i~ophorone dii30cyanate, 94.1 g of toluene and 40.5 g of methyl i obutyl ketone. 102.2 g of dimethylaminopropyl-amine were added at 20 to 25C, and the contents were sub~equently stirred for 30 minutes.
143 g of this product were added to 509 g of the phenolic Mannich typa cros~linking agent prepared in stage 1. Stirring was continued at 50C until the i80-cyanate value had dropped to zero.
Crosslinking agent 8 A reaction ves~el was charged with 222.2 g of isophorone diisocyanate, 94.1 g of toluene and 40.5 g of methyl isobutyl ketone. 103.2 g of dimetAylaminopropanol were added at 20 - 25C, and the contents were subse-quently ~tirred for 30 minutes.
143 g of this product were added to 509 g of the phenolic Mannich type cros~linking agent prepared in stage 1 of crosslinking agent 8. Stirring was continued at 50C until the isocyanate value had dropped to zero.
Crosslinking agent 9 A reaction vessel was charged with 174 g of toluylene diisocyanate, 94.1 g of toluene and 40.5 g of methyl isobutyl ketone. 103.2 g of dimethylaminopropanol were added at 20 - 25C, and the contents were subse-quently stirred for 30 minutes.
124 g of this product were added to 509 g of the phenolic Nannich type crosslinking agent prepared in stage 1 of crosslinking agent 8. Stirring was continued at 50 9C until the isocyanate value had dropped to zero.
Crosslinking agent 10 A reaction vessel wa8 charged with 375 g of diphenylmethane diisocyanate, 76 g of trimethylolpropane and 465 g of ethylglycol acetate. The content~ ware stirred at 50C until the NC0 content had dropped to the theore-tical value. Thereafter 168 g of dibutylamine and 20.6 g of dimethylaminopropanol were added, and the contents were stirred at 50C for 2 hours. Thereafter a mixture of 9 g of glacial acetic acid, 27 g of water and 12.2 g of ':
2~ 7~3 - 13 - O.Z. 0062/02081 glycide was added, and 60C was maintained for 3 hour3.
Cro~slinking agent 11 A reaction vessel was charged with 375 ~ of diphenylmethane diisocyanate, 76 g of trimethylolpropane S and 300 g of ethylglycol acetate. The contents were stirred at 60C until the NCO content had dropped to the theoretical value. ~hereafter 174.4 g of dibutylamine and 16 g of ethylthioethanol were added at 60C, and the contents were stirred for 2 hour~. After 166 g of butyl-glycol, 6 g of glacial acetic acid, 18 g of water and11.1 g of glycide had been added, the content~ were stirred at 60C for a further 3 hours.
Crosslinking agent 12 A reaction ves~el wa~ charged with 86 g of phenyl glycide ether in 100 g of isopropanol, followed at 70C
by a mixture of 61 g of thiodiglycol, 30 g of glacial acetic acid and 18 g of water. Ths contents were stirred at 70C for 4 hour~. This solution was added to 812 g of a 70% strength by weight solution of a diphenylmethane diisocyanate which had been half-blocked with dibutyl-amine, and the contents were stirred at 60C for 4 hour~.
Crosslinking agent 13 A reaction vessel was charged with 375 g of diphenylmethane diisocyanate, 76 g of trimethylolpropane 2S and 166 g of ethylglycol acetate. Stirring was continued at 50C until the NCO content had dropped to the theo-reti~al value. Thereafter 155 g of dibutylamine were added, and the contents were subsequently stirred for 30 minutes. 22.2 g of glycide were then added, and the contents were stirred at 50C for 3 hours.
This intermQdiate was then mixed with 60.6 g of tributyl phosphine, 18 g of glacial acetic acid and 54 g of water, and the contents were stirred at 50C for 2 hours.
Crosslinking agent 14 The intermediate for crosslinking agent 13 was used, but it was mixed with 30.3 g of triethylamine, 18 Z0~79 - 14 - O.Z. 0062/02081 of glacial acetic acid and 36 g of water.
Crosslinking agent 15 The intermediate for crosslinking agent 13 was used, but it was mixed with 38.3 g of thiodiglycol, 108 g of water and 18 g of glacial acetic acid.
Crosslinking aqent dispersion 1 686.7 g of crosqlinking agent 1, having a -qolid~
content of 60% by weight, were treated with 8.1 g of acetic acid. Thereafter 505.5 g of water were added a little at a time with stirring. A mixture of 300 g of ~olvent/water was then distilled off under reduced pressure at 40 - 50C while 300 g of water were added.
The re~ult obtained wa~ a finely divided, stable disper-sion.
Cro~linking agent dispersion 2 The procedure was as for diQpersion 1, but 6.3 g of acetic acid were used.
Crosslinking agent dispersion 3 The procedure was as for disper~ion 1, again affording a stable, finely divided dispersion.
Cros~linking agent dispersion 4 343.3 g of crosslinking agent 4, having a ~olid~
content of 60% by weight, were treated with 4.74 g of acetic acid. Thereafter 245.2 g of water were added a little at a time with stirring. The result obtained was a finely divided dispersion.
Croaslinking agent dispersion 5 The procedure was a~ for dispersion 4, except that 5.3 g of acetic acid were added.
Crosslinking agent dispersion 6 The procedure was as for dispersion 1, likewi~e affording a stable, finely divided dispersion.
Cro~slinking agent dispersion 7 294 g of crosslinking agent 7, having a solid3 content of 70% by weight, were mixed with 29.4 g of isobutanol. Thereafter 7.4 g of acetic acid were added, and the mixture was dispersed with 265 g of water by 2 ~ ~ 7 ~3 - 15 - O.Z. 0062/02081 Qtirring. Thereafter, while 100 g of water were added, a mixture of ~olvent and wat~r (200 g) wa~ di~tilled off under reduced pres~ure. The result obtained was a finely divided stable, readily filterahle dispersion.
Cro~slinking agent disper~ion 8 The procedure was as for cros31inking agent dispersion 7, except that cro~slinking agent 8 wa used.
Crosslinking agent disp~rsion 9 294 g of crosslinking agent 9, having a solids con-tent of 70% by weight, were mixed with 60 g of isobutanol.
4.5 g of glacial acetic acid were added, and the mixture was dispersed with 265 g of water while stirring. The re~ult obtained wa~ a finely divided, stable dispersion.
Crosslinking aqent dispersion 10 1,130 g of cros~linking agent 10 were mixed with 56 g of butylglycol and di~per~ed in 894 g of water.
Thereafter 400 g of solvent/water mixture were distilled off under reduced pres~ure.
Electrocoating bath 1 1,061.7 g of the binder dispersion, 775 g of the pigment paste and 926 g of crosslinking agent dispersion 4 were mixed and made up with water to a solids content of 20% by weight. Deposition at 300 V produced a coat 20 ~m in thickness. The coat was crosslinkable at a baking temperaturQ of 140C.
Electrocoating bath 2 The coating bath was made up in the same way as coating bath 1, except that cro3slinking agent dispersion 2 w~ used. Following the addition of 30 g of Napsol' PPH
(from SHELL) and aging for 7 days a deposition voltage of 300 V produced coats from 23 to 25 ~m in thickness. The deposited films were resi~tant to acetone after baking at 120C, showed excellent leveling and conferred outstand-ing corrosion protection.
Electrocoating bath 3 The procedure wa~ as for electrocoating bath 1 using the following ingredientss Z(:~21793~
- 16 - O.Z. 0062/02081 1,061.7 g of synthetic resin binder dispersion 775 g of pigment paste 902 g of cros~linking agent dispersion 1.
30 g/l of Napsol were added to the bath. After S aging for 7 days, deposition at 320 V produced a coat 18 ~m in thickne~s.
After baking at 120C for 20 minutes the film wa3 solvent-resistant, showed good leveling and conferred outstanding corrosion protection. The bath was stable over weeks, even then being free of sediment or coagulum.
Electrocoating bath 4 The procedure was as for coating bath 3, except that cros~linking agent dispersion 2 was used. After aging, deposition at 350 V gave a coat 19 ~m in thick-ness. After curing at 120C the film showed satisfactory leveling and solvent resistance.
Electrocoating bath 5 1,370 g of synthetic resin binder di~per-~ion, 775 g of pigment pa~te and 595 g of crosslinking agent dispersion 8 were used to prepare a bath as described under coating bath 1. Following addition of 20 g of Napsol PPH per 1 and aging for 7 days a deposition voltage of 280 V gave a coat 22 ~m in thickne~s which was solvent-resistant on baking at 140C. The properties of the bath were unchanged after 4 weekq' aging.
Electrocoating bath 6 Crosslinking agent dispersion 9 was used to preparo a bath a~ described under coating bath 5. Follow-ing addition of 25 g/l of Napsol PPH and aging for 7 days a deposition voltage of 300 V gave a coat of 23 ~m thick-ness which become solvent-resistant on baking at 140C.
After a further 4 weeks' aging, the bath was free of sediment or coagulum, and any films deposited therefrom were unchanged compared with the first deposited film.
Claims (11)
1. A heat-curable, cathodically depositable aqueous electrocoating composition, containing (A) from 50 to 95% by weight of a polymerization or polycondensation or polyaddition product which has an average molecular weight of from 200 to 20,000 and primary and/or secondary hydroxyl groups and primary, secondary and/or tertiary amino groups and is water-thinnable on protonation with an acid, and (B) from 5 to 50% by weight of a water-thinnable cross-linking agent having cationic groups or groups which are convertible into cationic groups by protonation with an acid.
2. A coating composition as claimed in claim 1, containing an aminoepoxy resin as component (A).
3. A coating composition as claimed in claim 1, containing a blocked polyisocyanate as crosslinking agent (B).
4. A coating composition as claimed in claim 1, containing a phenolic Mannich base as crosslinking agent (B).
5. A coating composition as claimed in claim 1, containing a crosslinking agent having tertiary amino groups or quaternary ammonium groups as component (B).
6. A coating composition as claimed in claim 1, containing a crosslinking agent having phosphonium or sulfonium groups as component (B).
7. A coating composition as claimed in claim 1, containing in addition an organic solvent in an amount of up to 20% by weight based on the total weight of the coating composition.
8. A coating composition as claimed in claim 1, containing in addition pigments, fillers and auxiliaries.
9. A coating composition as claimed in claim 1, obtainable by separate dispersing of components (A) and (B) in water and mixing of these dispersions.
- 18 - O.Z. 0062/02081
- 18 - O.Z. 0062/02081
10. A process for preparing a cathodic electro-coating, which comprises using a coating composition as claimed in claim 1 as electrocoating bath.
11. A coated object, obtainable using a coating composition as claimed in claim 1.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3902441A DE3902441A1 (en) | 1989-01-27 | 1989-01-27 | HEAT-CURABLE COATING AGENT FOR CATHODICAL ELECTRO-DIP PAINTING |
| DE3902441.5 | 1989-01-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2007934A1 true CA2007934A1 (en) | 1990-07-27 |
Family
ID=6372933
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002007934A Abandoned CA2007934A1 (en) | 1989-01-27 | 1990-01-17 | Heat-curable coating composition for cathodic electrocoating |
Country Status (11)
| Country | Link |
|---|---|
| US (1) | US5096555A (en) |
| EP (1) | EP0380009B1 (en) |
| JP (1) | JPH02233771A (en) |
| CN (1) | CN1033040C (en) |
| AT (1) | ATE120476T1 (en) |
| AU (1) | AU618448B2 (en) |
| BR (1) | BR9000341A (en) |
| CA (1) | CA2007934A1 (en) |
| DE (2) | DE3902441A1 (en) |
| ES (1) | ES2072926T3 (en) |
| ZA (1) | ZA90586B (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5074979B1 (en) * | 1990-06-20 | 1995-02-28 | Ppg Industries Inc | Cationic resin containing blocked isocyanate groups suitable for use in electrodeposition |
| DE4134302A1 (en) * | 1991-10-17 | 1993-04-22 | Basf Lacke & Farben | HEAT-CURABLE COATING AGENTS FOR THE CATHODIC ELECTRO-DIP PAINTING |
| US5461091A (en) * | 1991-10-17 | 1995-10-24 | Basf Aktiengesellschaft | Heat curable cathodic electrocoating composition |
| DE4207653A1 (en) * | 1992-03-11 | 1993-09-16 | Basf Lacke & Farben | SYNTHETIC RESINS |
| US5569733A (en) * | 1994-03-31 | 1996-10-29 | Ppg Industries, Inc. | Tertiary aminourea compositions and their use as catalysts in curable compositions |
| KR0174320B1 (en) * | 1994-07-15 | 1999-03-20 | 사사끼 요시오 | Process for preparing cationically electrodepositable coating composition |
| 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 |
| US6398934B1 (en) | 2000-10-19 | 2002-06-04 | E. I. Du Pont De Nemours And Company | Concentrate suitable for the preparation of cathodic electrodeposition coating compositions |
| US20030054193A1 (en) * | 2001-02-05 | 2003-03-20 | Mccollum Gregory J. | Photodegradation-resistant electrodepositable coating compositions and processes related thereto |
| US6869513B2 (en) * | 2001-11-08 | 2005-03-22 | Ppg Industries Ohio, Inc. | Photodegradation-resistant electrodepositable coating compositions with improved throw power and processes related thereto |
| JP2005173645A (en) * | 2003-12-05 | 2005-06-30 | Ibm Japan Ltd | Device and method for supporting program development, program, and recording medium |
| EP1956056A3 (en) * | 2007-02-09 | 2010-05-12 | E.I. Du Pont De Nemours And Company | Cathodic electrodeposition coating composition |
| CN101161742B (en) * | 2007-06-26 | 2010-12-08 | 广东雅图化工有限公司 | Bicomponent automobile cathode electrophoresis paint and preparation method thereof |
Family Cites Families (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2541801C3 (en) * | 1975-09-19 | 1981-07-02 | Basf Ag, 6700 Ludwigshafen | Process for the production of lacquer binders essentially free of epoxy groups and their use |
| DE2554080C3 (en) * | 1975-12-02 | 1981-02-26 | Basf Ag, 6700 Ludwigshafen | Process for the production of paint binders |
| NL7708567A (en) * | 1977-08-03 | 1979-02-06 | Akzo Nv | WATERY COATING COMPOSITION TO BE APPLIED CATAPHORETICALLY, METHOD FOR PREPARATION THEREOF, AND METHOD FOR APPLYING THE COMPOSITION. |
| US4338235A (en) * | 1979-12-21 | 1982-07-06 | E. I. Du Pont De Nemours And Company | Electrocoating composition with polyhydroxyamine and acrylic or methacrylic polymers |
| AU6133680A (en) * | 1980-06-30 | 1982-01-07 | E.I. Du Pont De Nemours And Company | Electrocoating with water-borne composition of epoxy resin, polymeric acid and tertiary amine |
| EP0054194A3 (en) * | 1980-12-15 | 1982-09-08 | Interox Chemicals Limited | Epoxy resins and emulsions made therefrom |
| DE3311516A1 (en) * | 1983-03-30 | 1984-10-04 | Basf Farben + Fasern Ag, 2000 Hamburg | HEAT-CURABLE COATING AGENTS AND THEIR USE |
| DE3325061A1 (en) * | 1983-07-12 | 1985-01-24 | Basf Farben + Fasern Ag, 2000 Hamburg | NITROGEN-BASED GROUPS CARRYING RESIN, THE PRODUCTION AND USE THEREOF |
| DE3331904A1 (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 |
| DE3422457A1 (en) * | 1984-06-16 | 1985-12-19 | Basf Farben + Fasern Ag, 2000 Hamburg | BINDING AGENTS FOR CATHODICAL ELECTRO DIP PAINTING CONTAINING NON-TERTIAL BASIC AMINO GROUPS IN ADDITION TO PHENOLIC MANNICH BASES |
| CA1304860C (en) * | 1985-04-19 | 1992-07-07 | Ding-Yu Chung | Method of electrodepositing cationic resin compositions without the need for volatile organic coalescent solvents |
| DE3518770A1 (en) * | 1985-05-24 | 1986-11-27 | BASF Lacke + Farben AG, 4400 Münster | WATER-DISCOVERABLE BINDING AGENTS FOR CATIONIC ELECTRO-DIP COATINGS AND METHOD FOR THEIR PRODUCTION |
| DE3518732A1 (en) * | 1985-05-24 | 1986-11-27 | BASF Lacke + Farben AG, 4400 Münster | WATER-DISCOVERABLE BINDING AGENTS FOR CATIONIC ELECTRO-DIP COATINGS AND METHOD FOR THEIR PRODUCTION |
| AT381500B (en) * | 1985-05-29 | 1986-10-27 | Vianova Kunstharz Ag | METHOD FOR PRODUCING CROSSLINKING COMPONENTS AND THE USE THEREOF FOR LACQUER BINDERS |
| MX168203B (en) * | 1985-07-22 | 1993-05-12 | Vianova Kunstharz Ag | PROCEDURE FOR THE PREPARATION OF BINDERS OF CATIONIC SELF-RETICULATING ENAMELS |
| JPH0626708B2 (en) * | 1985-09-10 | 1994-04-13 | 関西ペイント株式会社 | Composite coating formation method |
| AT383820B (en) * | 1985-09-25 | 1987-08-25 | Vianova Kunstharz Ag | METHOD FOR PRODUCING SELF-CROSS-LINKING CATHIONIC LACQUER BINDERS AND THE USE THEREOF |
| US4879013A (en) * | 1986-03-03 | 1989-11-07 | Ppg Industries, Inc. | Method of cationic electrodeposition using dissolution resistant anodes |
| AT385047B (en) * | 1986-05-27 | 1988-02-10 | Vianova Kunstharz Ag | METHOD FOR PRODUCING CATIONIC WATER-DETERMINATABLE BINDING AGENTS AND THE USE THEREOF |
| AT384820B (en) * | 1986-06-19 | 1988-01-11 | Vianova Kunstharz Ag | METHOD FOR THE PRODUCTION OF SELF-CROSS-LINKING CATIONIC LACQUER AND THE USE THEREOF |
| AT388739B (en) * | 1987-05-18 | 1989-08-25 | Vianova Kunstharz Ag | METHOD FOR PRODUCING SELF-CROSS-LINKING CATIONIC LACQUERS ON THE BASIS OF UREIDE-MODIFIED EPOXY RESINS AND THE USE THEREOF |
| DE3741661A1 (en) * | 1987-12-09 | 1989-06-22 | Basf Lacke & Farben | BINDING AGENT FOR CATHODIC ELECTRIC DIP PAINTING |
| DE3824552A1 (en) * | 1988-07-20 | 1990-02-08 | Basf Lacke & Farben | HEAT-CURABLE COATING AGENT WITH LOW BURNING TEMPERATURES |
-
1989
- 1989-01-27 DE DE3902441A patent/DE3902441A1/en not_active Withdrawn
-
1990
- 1990-01-17 CA CA002007934A patent/CA2007934A1/en not_active Abandoned
- 1990-01-20 AT AT90101154T patent/ATE120476T1/en active
- 1990-01-20 ES ES90101154T patent/ES2072926T3/en not_active Expired - Lifetime
- 1990-01-20 EP EP90101154A patent/EP0380009B1/en not_active Revoked
- 1990-01-20 DE DE59008781T patent/DE59008781D1/en not_active Revoked
- 1990-01-25 CN CN90100751A patent/CN1033040C/en not_active Expired - Fee Related
- 1990-01-25 US US07/470,380 patent/US5096555A/en not_active Expired - Fee Related
- 1990-01-26 BR BR909000341A patent/BR9000341A/en not_active Application Discontinuation
- 1990-01-26 JP JP2015131A patent/JPH02233771A/en active Pending
- 1990-01-26 ZA ZA90586A patent/ZA90586B/en unknown
- 1990-01-29 AU AU48789/90A patent/AU618448B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| DE3902441A1 (en) | 1990-08-16 |
| BR9000341A (en) | 1990-11-27 |
| EP0380009A2 (en) | 1990-08-01 |
| AU618448B2 (en) | 1991-12-19 |
| EP0380009A3 (en) | 1992-03-11 |
| AU4878990A (en) | 1990-08-02 |
| US5096555A (en) | 1992-03-17 |
| JPH02233771A (en) | 1990-09-17 |
| ATE120476T1 (en) | 1995-04-15 |
| ES2072926T3 (en) | 1995-08-01 |
| CN1033040C (en) | 1996-10-16 |
| CN1044483A (en) | 1990-08-08 |
| EP0380009B1 (en) | 1995-03-29 |
| DE59008781D1 (en) | 1995-05-04 |
| ZA90586B (en) | 1991-10-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |