CA2062272A1 - Dibutyltin oxide preparations and their use in catalysing the crosslinking reactions of cationic paint binders - Google Patents
Dibutyltin oxide preparations and their use in catalysing the crosslinking reactions of cationic paint bindersInfo
- Publication number
- CA2062272A1 CA2062272A1 CA002062272A CA2062272A CA2062272A1 CA 2062272 A1 CA2062272 A1 CA 2062272A1 CA 002062272 A CA002062272 A CA 002062272A CA 2062272 A CA2062272 A CA 2062272A CA 2062272 A1 CA2062272 A1 CA 2062272A1
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- Prior art keywords
- dibutyltin oxide
- parts
- cationic
- weight
- compositions
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Classifications
-
- 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
- C08G18/08—Processes
- C08G18/16—Catalysts
- C08G18/22—Catalysts containing metal compounds
- C08G18/24—Catalysts containing metal compounds of tin
- C08G18/242—Catalysts containing metal compounds of tin organometallic compounds containing tin-carbon bonds
-
- 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
-
- 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
- C09D5/4492—Cathodic paints containing special additives, e.g. grinding agents
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Molecular Biology (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Paints Or Removers (AREA)
- Polyurethanes Or Polyureas (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention relates to dibutyltin oxide compo-sitions, to a process for their production, and to their use in catalyzing the crosslinking reactions of cationic paint binders crosslinkable by transesterification and/or trans-urethanization. The dibutyltin oxide compositions are pre-pared by dispersion of dibutyltin oxide in a dispersion medium comprising at least one of a blocked polyisocyanate or a curing agent containing activated ester groups and, if appropriate, water-tolerant organic solvents inert to the dibutyltin oxide. The dibutyltin oxide compositions in com-bination with cationic modified epoxy resin binders or cati-onic acrylate copolymers are especially suitable for the formulation of cathodically depositable, corrosion-resistant primers, or of pastel-colored one coat or top coat paints.
The invention relates to dibutyltin oxide compo-sitions, to a process for their production, and to their use in catalyzing the crosslinking reactions of cationic paint binders crosslinkable by transesterification and/or trans-urethanization. The dibutyltin oxide compositions are pre-pared by dispersion of dibutyltin oxide in a dispersion medium comprising at least one of a blocked polyisocyanate or a curing agent containing activated ester groups and, if appropriate, water-tolerant organic solvents inert to the dibutyltin oxide. The dibutyltin oxide compositions in com-bination with cationic modified epoxy resin binders or cati-onic acrylate copolymers are especially suitable for the formulation of cathodically depositable, corrosion-resistant primers, or of pastel-colored one coat or top coat paints.
Description
2697~us360~ 2 FIELD OF INVENTION
The present invention relates to dibutyltin oxide compositions, to a process for their production, and to their use in catalyzing the crosslinking reactions of cationic paint binders.
BACKGROUND OF INVENTION
Cationic paint binders of the type which can be employed according to the present invention, especially for the formulation of cathodically depositable electrocoating paints, crosslink to a significant extent at elevated tem-perature by transurethanization, transesterification, or by the reaction of terminal double bonds. It is known that cr~sslinking reactions of this type are catalyzed by metal compounds. In the curing of cathodically deposited paint films, such a catalysis is necessary virtually in all cases in order to attain the spectrum of properties required by industrial users.
The most important catalysts presently used in industry are organic compounds of tetravalent tin which are employed, for example, as dibutyltin oxide ~C4H9)2SnO, as dibutyltin dilaurate (C4H9)2Sn(OcOc12H2s]z~ or as re~ction products of dibutyltin oxide with alcohols or phenols. How-ever, all the catalysts cited have disadvantages.
The present invention relates to dibutyltin oxide compositions, to a process for their production, and to their use in catalyzing the crosslinking reactions of cationic paint binders.
BACKGROUND OF INVENTION
Cationic paint binders of the type which can be employed according to the present invention, especially for the formulation of cathodically depositable electrocoating paints, crosslink to a significant extent at elevated tem-perature by transurethanization, transesterification, or by the reaction of terminal double bonds. It is known that cr~sslinking reactions of this type are catalyzed by metal compounds. In the curing of cathodically deposited paint films, such a catalysis is necessary virtually in all cases in order to attain the spectrum of properties required by industrial users.
The most important catalysts presently used in industry are organic compounds of tetravalent tin which are employed, for example, as dibutyltin oxide ~C4H9)2SnO, as dibutyltin dilaurate (C4H9)2Sn(OcOc12H2s]z~ or as re~ction products of dibutyltin oxide with alcohols or phenols. How-ever, all the catalysts cited have disadvantages.
2 ~J ~; ~J ~"'i r;~
2697tU53600 Thus, dibutyltin oxide is a solid which has to be incorporated in the paint batch in as finely divided a form as possible, since it is fully effective as a catalyst only in solution. Longer homogenization times are, therefore, necessary when this catalyst is employed. If the comminu-tion is effected by grinding in a paint binder, as is fre-quently the custom with pigments and extenders, then the catalytic efect of the dibutyltin oxide can be initiated by the temperature rise occurring in the grinding process, and the reactivity of the binder can be prematurely activated to an undesirable degree. On the other hand, the use of dis-persion media which are inert toward the binders gives rise to non-crosslinked molecular segments in the stoved film and is likewise undesirable. When dibutyltin dilaurate is used, acid is liberated by hydrolysis which can cause interfer-ence, especially in the operation of electrocoating plants.
Dibutyltin oxide and dibutyltin dilaurate are also often not fully compatible with the paint binders used. In many cases this impairs storage stability, especially that of dilute paints used as a topping-up material in electrocoatin~
plants.
Reaction products of dibutyltin oxide ~DBTO~ with alcohols or phenols, as described in European Patent No.
0,261,486 B1, possess in the ready-for-use paint excellent compatibility and stability. However, at the temperatures r~
2697/U536~0 necessary for the crosslinking of the deposited films, de-composition products form during the crosslinking process which cause surface defects in the stoved paint film, such as pinholing and cratering.
It has now been found that an industrially advan-tageous catalysis for the crosslinking reactions of cathodi-cally depositable paint binders for electrocoating paints is possible even using dibutyltin oxide, if the mechanical dis-persion of the dibutyltin oxide is effected in a curing com-ponent bearing crosslinkable groups. As a result of the uniform distribution of the catalyst in the dispersion med-ium, the temperatures necessary for the crosslinking reac-tions can be reduced.
SUMMARY OF INVENTION
Accordingly, the present invention relates to dibutyltin oxide compositions which are characterized in that they comprise dibutyltin oxide, present in a particle size of 0.1 to 5 ~m maximum after mechanical dispersion; and a dispersion medium of a blocked polyisocyanate and/or a curing component bearing activated ~ster groups, the dibu-tyltin oxide compositions having a dibutyltin oxide content of 5 to 30% by weight, preferably of 10 to 20% by weight, based on the tin content and on the solids content of the dispersion medium. If necessary, an organic solvent can be Z697/U536(~0 used in dissolving the blocked polyisocyanate and/or curing component which is inert to dibutyltin oxide.
The invention further relates to a process for the production of the compositions and to the use of the dibu-tyltin oxide compositions in catalyzing the crosslinking re-actions of cationic paint binders crosslinkable by trans-urethanization andlor transesterification for cathodically depositable electrocoating paints and to the cationic paints, especially to cathodically depositable electrocoat-ing paints, catalyzed by the dibutyltin oxide compositions according to the invention.
Any film-forming isocyanate compound can essen-tially be used as the blocked polyisocyanate provided that it contains a blocking agent which does not unblock at tem-peratures of up to 50C which must be maintained in the preparation of the dibutyltin oxide compositions.
Examples of curing components bearing activated ester groups are described, inter alia, in U.S. Patent No.
4,523,007 corresponding to Austrian Patent No. 379,602.
The viscosity of the dibutyltin oxide-containiny compositions can be adjusted to an advantageous value by using solvents which are chemically inert toward dibutyltin oxide and have an adequate water tolerance. 2,2,4-tri-methylpentanediol monoisobutyra~e sold under the brand name Z697/U53bOO 2 ~ & ~ ~ l r~
Texanol or the dialkyl ethers of diethylene or triethylene glycol are particularly suitable.
The dispersion of commercial dibutyltin oxide in the appropriate medium is performed using traditional grind-ing units such as bead mills or triple-roll mills. The ultimate particle size should be below 5 ~m.
The dibutyltin oxide compositions which have a dibutyltin oxide content of 5 to 30% by weight, preferably of 10 to 20% by weight, based on the tin content and on the solids content of the dispersion medium, can be added in concentrated form to the binder, to a pigment grinding resin that may be used, or to the pigment paste; protonization being carried out in conjunction with the binder, if appro-priate. However, provided that the preparations contain protonizable groups, they may also be added during the oper-ation of an electrocoating plant to the dilute paint or to the bath material in neutralized form and after treatment with water and/or auxiliary solvents.
The catalyzed electrocoating paints contain 0.1 to 3.0% by weight, preferably 0.5 to 1.5~ by weight, of tin, based on the binder solids, in the form of the dibutyltin oxids compositions.
The dibutyltin oxide compositions are also per-fectly compatible with the paint binders at low tempera-tures. Because of the organophilic nature of the dispersion ~r~s~
2697~U53600 medium, the dibutyltin oxide remains in the resin phase of the dilute paint and hence also in the film, largely freed from water by the endosmosis taking place during the elec-trocoating process.
The paint binders whose crosslinking reactions via transurethanization and/or transesterification can be cata-lyzed by the dibutyltin oxide compositions according to the invention are known to one skilled in the art. The dibutyl-tin oxide compositions according to the invention, in com-bination with cationic modified epoxy resins, are suitable especially for the formulation of corrosion-resistant pri-mers for automobiles and, in combination with cationic acrylic resins, for the formulation of pastel-colored one-coat paints or top-coat paints for domestic appliances. The temperatures necessary for the crosslinking reactions can be lowered as a resu~t of the uniform distribution of the cata~
lyst in the dispersion medium.
PRESENTLY PREFER ED EMBODIMENTS_ The examples below illustrate the invention with-out limiting its scope. All parts and percentages are by weight unless stated otherwise.
2697tU53600 ~ 2 7 ,J~
tA) Prep~ration of_the Dispersion Media (Al~ 134 parts (1.0 mole) of trimethylolpropane are reacted at 70C with 851 parts (2.8 moles) of a toluylene diisocyanate semi-blocked with 2-ethylhexanol in the pres-ence of 530 parts of diethylene glycol dimethyl ether, until all isocyanate groups are completely consumed (solids con-tent 65% by weight).
(A2) 696 parts (8.0 moles) of methyl ethyl ketoxime are reacted at 80C with 1554 parts (7.0 moles) of iso-phorone diisocyanate in the presence of 0.2 parts of tri-ethylamine as catalyst until all isocyanate groups are completely consumed. The solids content is 100% by weight.
This curing component is analogous to the curing component of Example 3 of Austrian Patent No. 390,624.
(A3) 149 parts (1.0 mole) of triethanolamine are reacted at 80~C with 1008 parts (3.0 moles) of a toluylene diisocyanate semi-blocked with diethylene glycol monobutyl ether in 500 parts of Texanol, until all isocyanate groups are completely consumed. The solids content is 70% by weight.
(A4) 33 g (1 mole) of 91~ paraformaldehyde are added in 6 portions at 60C to a mixture of 130 g (1 mole) of ethyl acetoacetate, 0.85 g (0.01 mole) of piperidine and 0.54 g (0.01 mole) of 85% formic acid. The paraformaldehyde added in any portion must be completely dissolved before 2697/Us3~00 ~ SV ~
adding additional paraformaldehyde, and the reaction temper-ature must be kept below 90c by cooling. After all of the paraformaldehyde has been added, the reaction mixture is stirred at 9ooc until the paraformaldehyde is completely dissolved. The temperature is raised to 140C over 2 hours, with water commencing to separate. The temperature is main-tained at 140C until a total of 24 g of water is distilled off using petroleum ether, boiling range 80 to 120C, as an entraining agent. The entraining agent used is then dis-tilled off under reduced pressure, and the temperature is kept at 120C until a refractive index n 20/D of 1.4750 is reached. The product has a solids content of about 94~ by weight. This curing agent is analogous to that of Example 2 of U.S. Patent No. 4,523,007 corresponding to Austrian Patent No. 379,602.
(B) Production of the Dibutyltin Oxide Composltions The dispersion medium and dibutyltin oxide (DBTO) are mixed to form a homogeneous mixture in accordance with the proportions stated in Table 1, and the mixture is ground in a suitable device, preferably in a bead mill or a triple-roll mill, to a particle size of about 3 ~m. The tempera-ture of the mill base should not exceed about 50C~ Table 1 is as follows:
Zo97/US3600 2 0 ~ tJ ~ 7 r~
~able l_ Preparation Dispersion Medium DBT0 Sn ~as metal) (Based on 100% Solids) ~ by wt.
X1 150 parts of (A1) 100 parts 19.1 K2 200 parts of (A2) 70 parts 12.4 K3 100 parts of (A3) 80 parts 21.2 K4 200 parts of (A4) 55 parts 10.3 . . .
(C) Preparation of the Binders Used in the Cathodically De~ositable Electrocoatina Paints of Table 2 (B1) 220 parts (1 mole) of nonylphenol are heated in a suitable reaction vessel at 75C with 130 parts (1 mole) of diethylaminopropylamine and 100 parts of toluene, and the mixture is then treated, with gentle cooling, with 33 parts (1 mole) of 91% paraformaldehyde. The temperature is slowly raised until azeotropic distillation occurs. When 21 parts of water of reaction have been separated off, the toluene is distilled off in vacuo and the product is dissolved in 167 parts of diethylene glycol dimethyl ether.
304 parts (1.0 mole) of a toluylene diisocyanate, semi-blocked with 2-ethylhexanol, are added at 30 to 40C
with cooling to the solution obtained in this way and the z6s7/us3600 2 ~ r r~
temperature is kept at 40C for 1.5 hours to an NCO-value of zero. The solids content is 71% by weight.
Subsequently, 475 parts of an epichlorohydrin-bisphenol A-based epoxy resin (epoxide equivalent weight 475) are dissolved in 200 parts of propylene glycol mono-methyl ether and 835 parts of the intermediate prepared above are added and the reaction is allowed to proceed at 95 to 100~C to an epoxide value of zero. The solids cont~nt is 71% by weight.
(B2) 1000 parts of an epichlorohydrin-bisphenol A-based epoxy resin tepoxide equivalent weight about 500), contained in a reaction vessel fitted with a stlrrer, ther-mometer and reflux condenser, are dissolved in 492 parts of ethyl glycol acetate at 60 to 70C. 0.2 part of hydro-quinone and 144 parts (2.0 moles) of acrylic acid are added, and the temperature is raised to 100-llOC. The reaction is allowed to proceed at this temperature to an acid value of below 5 mg KOH/g. The reaction product is then treated at 60 to 70C with 652 parts (1.6 mole) o~ a monoisocyanate ob-tained from 1 mole of toluylene diisocyanate and l mole of diethylethanolamine (70% solution in methyl isobutyl ketone), and the reaction is allowed to proceed to an NCO-value of zero. The solids content is 706 by weight.
(B3) 667 parts of propylene glycol monomethyl ether, contained in a reaction vessel suitable for solution poly-r~
merization, are heated to 90C. A mixture of 120 parts ofN,N-dimethylaminoethyl methacrylate, 240 parts of 2-hydroxy-ethyl methacrylate, 420 parts of butyl acrylate, 336 parts of methyl methacrylate, 84 parts of 2-ethylhexyl acrylate, 36 parts of azobisisobutyronitrile, and 3.6 parts of ter-tiary dodecylmercaptan are added at a uniform rate over a period of 3 hours. Two hours after the end of the addition, a further 12 parts of azobisisobutyronitrile are added. The mixture is kept at 90C for a further two hours. The end product has a solids content of 65% by weight, an amine value of 36 mg KOH/g, and a hydroxyl value of 86 mg KOH/g;
in each case based on the 100% resin solids.
123 parts of this basic acrylate copolymer are mixed at 35C for about 2 hours with 20 parts of a curing component corresponding to the dispersion medium (A2).
(D) Preparation of Cathodically Depositable Electro-coating Paints Catalyzed by the Dibutyltin Oxide Compositions and Performance Testinq Thereof Pigmented paints are prepared in a known manner in accordance with the data summarized in Table 2. Table 2 is as follows:
7 rJ
2b97/US3bOO
_~
o In o o o ~ e ~J u) ~
O a~ O ~ rt (U
O
,~
o ~ a) ~1 ~ rl Q. ~a x x ~ x ~ R
o-~ ~ ~ ~ ~ ~o\o 3~ O O o o O
~ ~ I` C~ O ~D O
Q ~ O . . . ~ .
a~ o o ~1 o ~1 ~ 1 o\ ~ ~ O
~I R
E~ o a -,~
o ~-,~ ~
O S~ ~ 1 X--~ X
00XU U~ O
ra~5 ,~
P.
~1 ~'~ U ~
o .a o ~ ,4 ~ ~ _ IJ H H H H H ~ ~J R
. Ul ID 11~ _ _ _r _ _~
-~
o o ~ ~ O O O O
u~
v O
.~
t) ~ ~ ~r o -- a o t) o o o o o o ,~
~ ~ U~ r ..
O H H
~ ~ ' O O
.
O ~ O
r 1 1 Vl U~
~1 m m m m m O ho m Or~
O O ~ ~) r~ Ul ~ ~
Q) a~
, ~ ~
~
a o~ ~
,î
2 ~ ~j r / ~ 7 ;~
2697/U5360û
The paints of Table 2, diluted with deionized water to a solids content of 20% by weight, are sedimenta-tion stable for 3 weeks at room temperature. Stir stability (stirring of the paint in an open vessel at room tempera-ture) is satisfactory for all paints after 8 weeks, i.e., no changes in the stoved paint films are discernible.
The paints of Table 2 are electrically deposited on a degreased steel sheet, the conditions being chosen in order that the film thickness of the stoved films is about 20 + 2 ~m. The stoving temperature required for the cross-linking of the deposited films is set forth in Table 2. All ~rosslinked films obtained are resistant to 200 double strokes with methyl ethyl ketone.
Com~arison Example For comparison, a paint corresponding to Example 5 was catalyzed by the addition of dibutyltin oxide to the binder combination of basic acrylate copolymer and blocked polyisocyanate (A2) instead of the dibutyltin oxide composi-tion according to the invention. The stoving temperature required for the crosslinking of the film is 165C.
As will be apparently to one skilled in the art, various modifications can be made within the scope of the aforesaid description. Such modifications being within the 2 ~ ) ~J7 ~ 7 r ~
ability of one skilled in the art form a part of the present invention and are embraced by the appended claims.
2697tU53600 Thus, dibutyltin oxide is a solid which has to be incorporated in the paint batch in as finely divided a form as possible, since it is fully effective as a catalyst only in solution. Longer homogenization times are, therefore, necessary when this catalyst is employed. If the comminu-tion is effected by grinding in a paint binder, as is fre-quently the custom with pigments and extenders, then the catalytic efect of the dibutyltin oxide can be initiated by the temperature rise occurring in the grinding process, and the reactivity of the binder can be prematurely activated to an undesirable degree. On the other hand, the use of dis-persion media which are inert toward the binders gives rise to non-crosslinked molecular segments in the stoved film and is likewise undesirable. When dibutyltin dilaurate is used, acid is liberated by hydrolysis which can cause interfer-ence, especially in the operation of electrocoating plants.
Dibutyltin oxide and dibutyltin dilaurate are also often not fully compatible with the paint binders used. In many cases this impairs storage stability, especially that of dilute paints used as a topping-up material in electrocoatin~
plants.
Reaction products of dibutyltin oxide ~DBTO~ with alcohols or phenols, as described in European Patent No.
0,261,486 B1, possess in the ready-for-use paint excellent compatibility and stability. However, at the temperatures r~
2697/U536~0 necessary for the crosslinking of the deposited films, de-composition products form during the crosslinking process which cause surface defects in the stoved paint film, such as pinholing and cratering.
It has now been found that an industrially advan-tageous catalysis for the crosslinking reactions of cathodi-cally depositable paint binders for electrocoating paints is possible even using dibutyltin oxide, if the mechanical dis-persion of the dibutyltin oxide is effected in a curing com-ponent bearing crosslinkable groups. As a result of the uniform distribution of the catalyst in the dispersion med-ium, the temperatures necessary for the crosslinking reac-tions can be reduced.
SUMMARY OF INVENTION
Accordingly, the present invention relates to dibutyltin oxide compositions which are characterized in that they comprise dibutyltin oxide, present in a particle size of 0.1 to 5 ~m maximum after mechanical dispersion; and a dispersion medium of a blocked polyisocyanate and/or a curing component bearing activated ~ster groups, the dibu-tyltin oxide compositions having a dibutyltin oxide content of 5 to 30% by weight, preferably of 10 to 20% by weight, based on the tin content and on the solids content of the dispersion medium. If necessary, an organic solvent can be Z697/U536(~0 used in dissolving the blocked polyisocyanate and/or curing component which is inert to dibutyltin oxide.
The invention further relates to a process for the production of the compositions and to the use of the dibu-tyltin oxide compositions in catalyzing the crosslinking re-actions of cationic paint binders crosslinkable by trans-urethanization andlor transesterification for cathodically depositable electrocoating paints and to the cationic paints, especially to cathodically depositable electrocoat-ing paints, catalyzed by the dibutyltin oxide compositions according to the invention.
Any film-forming isocyanate compound can essen-tially be used as the blocked polyisocyanate provided that it contains a blocking agent which does not unblock at tem-peratures of up to 50C which must be maintained in the preparation of the dibutyltin oxide compositions.
Examples of curing components bearing activated ester groups are described, inter alia, in U.S. Patent No.
4,523,007 corresponding to Austrian Patent No. 379,602.
The viscosity of the dibutyltin oxide-containiny compositions can be adjusted to an advantageous value by using solvents which are chemically inert toward dibutyltin oxide and have an adequate water tolerance. 2,2,4-tri-methylpentanediol monoisobutyra~e sold under the brand name Z697/U53bOO 2 ~ & ~ ~ l r~
Texanol or the dialkyl ethers of diethylene or triethylene glycol are particularly suitable.
The dispersion of commercial dibutyltin oxide in the appropriate medium is performed using traditional grind-ing units such as bead mills or triple-roll mills. The ultimate particle size should be below 5 ~m.
The dibutyltin oxide compositions which have a dibutyltin oxide content of 5 to 30% by weight, preferably of 10 to 20% by weight, based on the tin content and on the solids content of the dispersion medium, can be added in concentrated form to the binder, to a pigment grinding resin that may be used, or to the pigment paste; protonization being carried out in conjunction with the binder, if appro-priate. However, provided that the preparations contain protonizable groups, they may also be added during the oper-ation of an electrocoating plant to the dilute paint or to the bath material in neutralized form and after treatment with water and/or auxiliary solvents.
The catalyzed electrocoating paints contain 0.1 to 3.0% by weight, preferably 0.5 to 1.5~ by weight, of tin, based on the binder solids, in the form of the dibutyltin oxids compositions.
The dibutyltin oxide compositions are also per-fectly compatible with the paint binders at low tempera-tures. Because of the organophilic nature of the dispersion ~r~s~
2697~U53600 medium, the dibutyltin oxide remains in the resin phase of the dilute paint and hence also in the film, largely freed from water by the endosmosis taking place during the elec-trocoating process.
The paint binders whose crosslinking reactions via transurethanization and/or transesterification can be cata-lyzed by the dibutyltin oxide compositions according to the invention are known to one skilled in the art. The dibutyl-tin oxide compositions according to the invention, in com-bination with cationic modified epoxy resins, are suitable especially for the formulation of corrosion-resistant pri-mers for automobiles and, in combination with cationic acrylic resins, for the formulation of pastel-colored one-coat paints or top-coat paints for domestic appliances. The temperatures necessary for the crosslinking reactions can be lowered as a resu~t of the uniform distribution of the cata~
lyst in the dispersion medium.
PRESENTLY PREFER ED EMBODIMENTS_ The examples below illustrate the invention with-out limiting its scope. All parts and percentages are by weight unless stated otherwise.
2697tU53600 ~ 2 7 ,J~
tA) Prep~ration of_the Dispersion Media (Al~ 134 parts (1.0 mole) of trimethylolpropane are reacted at 70C with 851 parts (2.8 moles) of a toluylene diisocyanate semi-blocked with 2-ethylhexanol in the pres-ence of 530 parts of diethylene glycol dimethyl ether, until all isocyanate groups are completely consumed (solids con-tent 65% by weight).
(A2) 696 parts (8.0 moles) of methyl ethyl ketoxime are reacted at 80C with 1554 parts (7.0 moles) of iso-phorone diisocyanate in the presence of 0.2 parts of tri-ethylamine as catalyst until all isocyanate groups are completely consumed. The solids content is 100% by weight.
This curing component is analogous to the curing component of Example 3 of Austrian Patent No. 390,624.
(A3) 149 parts (1.0 mole) of triethanolamine are reacted at 80~C with 1008 parts (3.0 moles) of a toluylene diisocyanate semi-blocked with diethylene glycol monobutyl ether in 500 parts of Texanol, until all isocyanate groups are completely consumed. The solids content is 70% by weight.
(A4) 33 g (1 mole) of 91~ paraformaldehyde are added in 6 portions at 60C to a mixture of 130 g (1 mole) of ethyl acetoacetate, 0.85 g (0.01 mole) of piperidine and 0.54 g (0.01 mole) of 85% formic acid. The paraformaldehyde added in any portion must be completely dissolved before 2697/Us3~00 ~ SV ~
adding additional paraformaldehyde, and the reaction temper-ature must be kept below 90c by cooling. After all of the paraformaldehyde has been added, the reaction mixture is stirred at 9ooc until the paraformaldehyde is completely dissolved. The temperature is raised to 140C over 2 hours, with water commencing to separate. The temperature is main-tained at 140C until a total of 24 g of water is distilled off using petroleum ether, boiling range 80 to 120C, as an entraining agent. The entraining agent used is then dis-tilled off under reduced pressure, and the temperature is kept at 120C until a refractive index n 20/D of 1.4750 is reached. The product has a solids content of about 94~ by weight. This curing agent is analogous to that of Example 2 of U.S. Patent No. 4,523,007 corresponding to Austrian Patent No. 379,602.
(B) Production of the Dibutyltin Oxide Composltions The dispersion medium and dibutyltin oxide (DBTO) are mixed to form a homogeneous mixture in accordance with the proportions stated in Table 1, and the mixture is ground in a suitable device, preferably in a bead mill or a triple-roll mill, to a particle size of about 3 ~m. The tempera-ture of the mill base should not exceed about 50C~ Table 1 is as follows:
Zo97/US3600 2 0 ~ tJ ~ 7 r~
~able l_ Preparation Dispersion Medium DBT0 Sn ~as metal) (Based on 100% Solids) ~ by wt.
X1 150 parts of (A1) 100 parts 19.1 K2 200 parts of (A2) 70 parts 12.4 K3 100 parts of (A3) 80 parts 21.2 K4 200 parts of (A4) 55 parts 10.3 . . .
(C) Preparation of the Binders Used in the Cathodically De~ositable Electrocoatina Paints of Table 2 (B1) 220 parts (1 mole) of nonylphenol are heated in a suitable reaction vessel at 75C with 130 parts (1 mole) of diethylaminopropylamine and 100 parts of toluene, and the mixture is then treated, with gentle cooling, with 33 parts (1 mole) of 91% paraformaldehyde. The temperature is slowly raised until azeotropic distillation occurs. When 21 parts of water of reaction have been separated off, the toluene is distilled off in vacuo and the product is dissolved in 167 parts of diethylene glycol dimethyl ether.
304 parts (1.0 mole) of a toluylene diisocyanate, semi-blocked with 2-ethylhexanol, are added at 30 to 40C
with cooling to the solution obtained in this way and the z6s7/us3600 2 ~ r r~
temperature is kept at 40C for 1.5 hours to an NCO-value of zero. The solids content is 71% by weight.
Subsequently, 475 parts of an epichlorohydrin-bisphenol A-based epoxy resin (epoxide equivalent weight 475) are dissolved in 200 parts of propylene glycol mono-methyl ether and 835 parts of the intermediate prepared above are added and the reaction is allowed to proceed at 95 to 100~C to an epoxide value of zero. The solids cont~nt is 71% by weight.
(B2) 1000 parts of an epichlorohydrin-bisphenol A-based epoxy resin tepoxide equivalent weight about 500), contained in a reaction vessel fitted with a stlrrer, ther-mometer and reflux condenser, are dissolved in 492 parts of ethyl glycol acetate at 60 to 70C. 0.2 part of hydro-quinone and 144 parts (2.0 moles) of acrylic acid are added, and the temperature is raised to 100-llOC. The reaction is allowed to proceed at this temperature to an acid value of below 5 mg KOH/g. The reaction product is then treated at 60 to 70C with 652 parts (1.6 mole) o~ a monoisocyanate ob-tained from 1 mole of toluylene diisocyanate and l mole of diethylethanolamine (70% solution in methyl isobutyl ketone), and the reaction is allowed to proceed to an NCO-value of zero. The solids content is 706 by weight.
(B3) 667 parts of propylene glycol monomethyl ether, contained in a reaction vessel suitable for solution poly-r~
merization, are heated to 90C. A mixture of 120 parts ofN,N-dimethylaminoethyl methacrylate, 240 parts of 2-hydroxy-ethyl methacrylate, 420 parts of butyl acrylate, 336 parts of methyl methacrylate, 84 parts of 2-ethylhexyl acrylate, 36 parts of azobisisobutyronitrile, and 3.6 parts of ter-tiary dodecylmercaptan are added at a uniform rate over a period of 3 hours. Two hours after the end of the addition, a further 12 parts of azobisisobutyronitrile are added. The mixture is kept at 90C for a further two hours. The end product has a solids content of 65% by weight, an amine value of 36 mg KOH/g, and a hydroxyl value of 86 mg KOH/g;
in each case based on the 100% resin solids.
123 parts of this basic acrylate copolymer are mixed at 35C for about 2 hours with 20 parts of a curing component corresponding to the dispersion medium (A2).
(D) Preparation of Cathodically Depositable Electro-coating Paints Catalyzed by the Dibutyltin Oxide Compositions and Performance Testinq Thereof Pigmented paints are prepared in a known manner in accordance with the data summarized in Table 2. Table 2 is as follows:
7 rJ
2b97/US3bOO
_~
o In o o o ~ e ~J u) ~
O a~ O ~ rt (U
O
,~
o ~ a) ~1 ~ rl Q. ~a x x ~ x ~ R
o-~ ~ ~ ~ ~ ~o\o 3~ O O o o O
~ ~ I` C~ O ~D O
Q ~ O . . . ~ .
a~ o o ~1 o ~1 ~ 1 o\ ~ ~ O
~I R
E~ o a -,~
o ~-,~ ~
O S~ ~ 1 X--~ X
00XU U~ O
ra~5 ,~
P.
~1 ~'~ U ~
o .a o ~ ,4 ~ ~ _ IJ H H H H H ~ ~J R
. Ul ID 11~ _ _ _r _ _~
-~
o o ~ ~ O O O O
u~
v O
.~
t) ~ ~ ~r o -- a o t) o o o o o o ,~
~ ~ U~ r ..
O H H
~ ~ ' O O
.
O ~ O
r 1 1 Vl U~
~1 m m m m m O ho m Or~
O O ~ ~) r~ Ul ~ ~
Q) a~
, ~ ~
~
a o~ ~
,î
2 ~ ~j r / ~ 7 ;~
2697/U5360û
The paints of Table 2, diluted with deionized water to a solids content of 20% by weight, are sedimenta-tion stable for 3 weeks at room temperature. Stir stability (stirring of the paint in an open vessel at room tempera-ture) is satisfactory for all paints after 8 weeks, i.e., no changes in the stoved paint films are discernible.
The paints of Table 2 are electrically deposited on a degreased steel sheet, the conditions being chosen in order that the film thickness of the stoved films is about 20 + 2 ~m. The stoving temperature required for the cross-linking of the deposited films is set forth in Table 2. All ~rosslinked films obtained are resistant to 200 double strokes with methyl ethyl ketone.
Com~arison Example For comparison, a paint corresponding to Example 5 was catalyzed by the addition of dibutyltin oxide to the binder combination of basic acrylate copolymer and blocked polyisocyanate (A2) instead of the dibutyltin oxide composi-tion according to the invention. The stoving temperature required for the crosslinking of the film is 165C.
As will be apparently to one skilled in the art, various modifications can be made within the scope of the aforesaid description. Such modifications being within the 2 ~ ) ~J7 ~ 7 r ~
ability of one skilled in the art form a part of the present invention and are embraced by the appended claims.
Claims (8)
1. Dibutyltin oxide compositions comprising dibutyltin oxide present in a particle size of 0.1 to 5 µm maximum and a dispersion medium comprising at least one of a blocked polyisocyanate or a curing component having acti-vated ester groups, said dibutyltin oxide compositions having a dibutyltin oxide content of 5 to 30% by weight based on the tin content and on the solids content of the dispersion medium.
2. The dibutyltin oxide compositions of claim 1 wherein the dibutyltin oxide content is from 10 to 20% by weight.
3. The dibutyltin oxide compositions of claims 1 or 2 wherein the dispersion medium includes an organic solvent inert to said dibutyltin oxide.
4. A process for the production of the dibutyltin oxide compositions of any one of claims 1-3 wherein said dibutyltin oxide is mechanically dispersed in said dispers-ing medium.
5. A catalyzed cationic paint comprising a paint binder and 0.1 to 3.0% by weight of tin, calculated on the binder solids, contributed by a dibutyltin oxide composition of any one of claims 1-3.
6. The catalyzed cationic paint of claim 5 wherein the tin content is from 0.5 to 1.5% by weight of tin, calculated on the binder solids.
7. The catalyzed cationic paints according to claims 5 or 6 wherein the binder includes a cationic modified epoxy resin.
8. The catalyzed cationic paints according to claims 5 or 6 wherein the binder includes a cationic acrylate copolymer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT0045991A AT396372B (en) | 1991-03-05 | 1991-03-05 | DIBUTYLZINNOXIDE PREPARATIONS AND THEIR USE FOR CATALYZING THE CROSSLINKING REACTIONS OF CATIONIC LACQUER BINDERS |
| ATA-459/91 | 1991-03-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2062272A1 true CA2062272A1 (en) | 1992-09-06 |
Family
ID=3491194
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002062272A Abandoned CA2062272A1 (en) | 1991-03-05 | 1992-03-04 | Dibutyltin oxide preparations and their use in catalysing the crosslinking reactions of cationic paint binders |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0507086B1 (en) |
| JP (1) | JPH0565438A (en) |
| KR (1) | KR920018174A (en) |
| AT (1) | AT396372B (en) |
| CA (1) | CA2062272A1 (en) |
| DE (1) | DE59200710D1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6174422B1 (en) | 1996-04-05 | 2001-01-16 | Herberts Gmbh | Acid-free catalyst paste, its production and its use in cathodic electro-dip coating |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4248898B2 (en) | 2003-03-05 | 2009-04-02 | 本田技研工業株式会社 | Lead-free electrodeposition coating composition and paint |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3044106A1 (en) * | 1979-11-30 | 1981-09-03 | Yoshitomi Pharmaceutical Industries, Ltd., Osaka | METHOD FOR PRODUCING POLYURETHANES |
| AT390808B (en) * | 1986-09-19 | 1990-07-10 | Vianova Kunstharz Ag | USE OF TIN CONDENSATION PRODUCTS FOR CATALYZING THE CROSSLINKING REACTIONS OF CATHODICALLY DEPOSITABLE VARNISH BINDERS |
| US4981925A (en) * | 1989-10-20 | 1991-01-01 | Air Products And Chemicals, Inc. | Cationic electrodepositable compositions of partially-blocked polyisocyanates and amine-epoxy resins containing polymeric diorganotin catalysts |
-
1991
- 1991-03-05 AT AT0045991A patent/AT396372B/en not_active IP Right Cessation
-
1992
- 1992-02-29 EP EP92103493A patent/EP0507086B1/en not_active Revoked
- 1992-02-29 DE DE59200710T patent/DE59200710D1/en not_active Revoked
- 1992-03-04 KR KR1019920003520A patent/KR920018174A/en not_active Application Discontinuation
- 1992-03-04 JP JP4046650A patent/JPH0565438A/en not_active Withdrawn
- 1992-03-04 CA CA002062272A patent/CA2062272A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6174422B1 (en) | 1996-04-05 | 2001-01-16 | Herberts Gmbh | Acid-free catalyst paste, its production and its use in cathodic electro-dip coating |
Also Published As
| Publication number | Publication date |
|---|---|
| AT396372B (en) | 1993-08-25 |
| JPH0565438A (en) | 1993-03-19 |
| EP0507086B1 (en) | 1994-11-02 |
| DE59200710D1 (en) | 1994-12-08 |
| KR920018174A (en) | 1992-10-21 |
| EP0507086A1 (en) | 1992-10-07 |
| ATA45991A (en) | 1992-12-15 |
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