CA1085079A - Cathodically depositable compositions for electrodeposition - Google Patents
Cathodically depositable compositions for electrodepositionInfo
- Publication number
- CA1085079A CA1085079A CA291,630A CA291630A CA1085079A CA 1085079 A CA1085079 A CA 1085079A CA 291630 A CA291630 A CA 291630A CA 1085079 A CA1085079 A CA 1085079A
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- Prior art keywords
- unsaturated
- weight
- acrylate
- meth
- optionally
- Prior art date
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-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F299/00—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers
- C08F299/02—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers from unsaturated polycondensates
- C08F299/026—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers from unsaturated polycondensates from the reaction products of polyepoxides and unsaturated monocarboxylic acids, their anhydrides, halogenides or esters with low molecular weight
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
- C09D5/4419—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications with polymers obtained otherwise than by polymerisation reactions only involving carbon-to-carbon unsaturated bonds
- C09D5/443—Polyepoxides
- C09D5/4457—Polyepoxides containing special additives, e.g. pigments, polymeric particles
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Polymers & Plastics (AREA)
- Molecular Biology (AREA)
- Medicinal Chemistry (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Paints Or Removers (AREA)
- Polyurethanes Or Polyureas (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Epoxy Compounds (AREA)
- Epoxy Resins (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Heat curable, cathodically depositable, aqueous coating com-positions comprising an aqueous emulsion of 98 to 50 percent by weight, preferably 95 to 70 percent by weight, of one or more self-crosslinking cationic binders based on modified epoxy compounds, water-soluble upon partial or total neutralization with an inorganic or organic acid, and 2 to 50 percent by weight, preferably 5 to 30 percent by weight, of a di- and/or triurethane having the formula - wherein R represents an aromatic, cycloaliphatic, or aliphatic hydrocarbon radical; R1 stands for a hydroxyethyl(meth)acrylate or a hydroxypropyl-(meth)acrylate radical; R2 is the radical of a saturated and/or unsaturated aliphatic monoalcohol with at least 6 carbon atoms and/or an alkyl or alkylene radical with at least 6 carbon atoms, and n is an integer of 1 or 2.
The coating compositions cure at low temperatures and short curing times to provide films having excellent resistance to water, chemicals, and cor-rosion; and have good leveling characteristics and good adherence to di-verse substrates.
Heat curable, cathodically depositable, aqueous coating com-positions comprising an aqueous emulsion of 98 to 50 percent by weight, preferably 95 to 70 percent by weight, of one or more self-crosslinking cationic binders based on modified epoxy compounds, water-soluble upon partial or total neutralization with an inorganic or organic acid, and 2 to 50 percent by weight, preferably 5 to 30 percent by weight, of a di- and/or triurethane having the formula - wherein R represents an aromatic, cycloaliphatic, or aliphatic hydrocarbon radical; R1 stands for a hydroxyethyl(meth)acrylate or a hydroxypropyl-(meth)acrylate radical; R2 is the radical of a saturated and/or unsaturated aliphatic monoalcohol with at least 6 carbon atoms and/or an alkyl or alkylene radical with at least 6 carbon atoms, and n is an integer of 1 or 2.
The coating compositions cure at low temperatures and short curing times to provide films having excellent resistance to water, chemicals, and cor-rosion; and have good leveling characteristics and good adherence to di-verse substrates.
Description
-~ 122`7/1310 !
FIELD OF INVENTION A~D BACKGROU~D
.
The present invention is directed to the preparation ofJ and coat-ing compositions which are water-dilutable upon neutralization with acids, The coating compositions are electrically depositable at the cathode of an electrodeposition system and will crosslink through thermal polymerization, Electrodeposition of synthetic resins and plastics, although known for quite some time, has gained technical importance as a coating proces3 in only recent years. The coating compositions or binders primarily used commercially for electrodeposition contain polycarboxylic acid resins neu-tralized with bases. The products deposit at the anode of an electrodeposition system. Owing to the acidic character of the resins, they are sensitive to corroding influences exerted by salts and particularly by alkalis. Further-more, coatings of the aforesaid compositions tend to undergo spot discolor-ation or undergo other chemical changes as a result of the metal ions anodically dissolved from the anode~ Accordingly, there is a desire to use coating compositions which will deposit at the cathode of an electrodeposition system.
There are a substantial number of binders disclosed in the liter-ature carrying groupings neutralizable with acid9 which can be deposited on cathodically wired objects of an electrodeposition system, Many have dis-advantages prirnarily due to the need to have crosslinking additives in the coating compositions which adversely affect film characteristics. Recently, however, coating compositions have been provided which are self-cross-linking through thermal polymerization. These selE-crosslinking binders include bmders comprising -.
- .. . . . ............ . - . .
~, ' , . . ' , . ' : ,. . . .
~A) the reaction products of diepoxy compounds with alpha, beta-unsaturated acids and, optionally, long chain fatty acids, and basic monoisocyanates;
(B) reaction products of diepoxy compounds with monoamines and, optionally, fatty acids, and unsaturated monoisocyanates; and ~C) two ~oles of a diepoxy compound plus one mole of a primary-tertiary or secondary~secondary diamine plus two moles of an alpha,beta-unsaturated monocarboxylic acid and, optionally, an unsaturated fatty acid, plus an unsaturatet monoisocyanate.
The aforesaid binders are highly desirable due to their ability to self-cross-link through the presence of alpha,beta-unsaturation; their being water-soluble in the presence of acids due to the basic nitrogen atoms, and their ability to provide excellent films with good performance characteristics, particularly regarding resistance to corroding influences. At times, how-ever, these binders provide films having certain deficiencies as a result of poor lev01ing of the coating composition on certain substrates and a gen-erally reduced adhesion on certain substrates, particularly untreated steel.
OBJECTS OF THE INVENTION AND GENER~L DESCRIPTION
'I It has now been found that the above-noted disadvantages with
FIELD OF INVENTION A~D BACKGROU~D
.
The present invention is directed to the preparation ofJ and coat-ing compositions which are water-dilutable upon neutralization with acids, The coating compositions are electrically depositable at the cathode of an electrodeposition system and will crosslink through thermal polymerization, Electrodeposition of synthetic resins and plastics, although known for quite some time, has gained technical importance as a coating proces3 in only recent years. The coating compositions or binders primarily used commercially for electrodeposition contain polycarboxylic acid resins neu-tralized with bases. The products deposit at the anode of an electrodeposition system. Owing to the acidic character of the resins, they are sensitive to corroding influences exerted by salts and particularly by alkalis. Further-more, coatings of the aforesaid compositions tend to undergo spot discolor-ation or undergo other chemical changes as a result of the metal ions anodically dissolved from the anode~ Accordingly, there is a desire to use coating compositions which will deposit at the cathode of an electrodeposition system.
There are a substantial number of binders disclosed in the liter-ature carrying groupings neutralizable with acid9 which can be deposited on cathodically wired objects of an electrodeposition system, Many have dis-advantages prirnarily due to the need to have crosslinking additives in the coating compositions which adversely affect film characteristics. Recently, however, coating compositions have been provided which are self-cross-linking through thermal polymerization. These selE-crosslinking binders include bmders comprising -.
- .. . . . ............ . - . .
~, ' , . . ' , . ' : ,. . . .
~A) the reaction products of diepoxy compounds with alpha, beta-unsaturated acids and, optionally, long chain fatty acids, and basic monoisocyanates;
(B) reaction products of diepoxy compounds with monoamines and, optionally, fatty acids, and unsaturated monoisocyanates; and ~C) two ~oles of a diepoxy compound plus one mole of a primary-tertiary or secondary~secondary diamine plus two moles of an alpha,beta-unsaturated monocarboxylic acid and, optionally, an unsaturated fatty acid, plus an unsaturatet monoisocyanate.
The aforesaid binders are highly desirable due to their ability to self-cross-link through the presence of alpha,beta-unsaturation; their being water-soluble in the presence of acids due to the basic nitrogen atoms, and their ability to provide excellent films with good performance characteristics, particularly regarding resistance to corroding influences. At times, how-ever, these binders provide films having certain deficiencies as a result of poor lev01ing of the coating composition on certain substrates and a gen-erally reduced adhesion on certain substrates, particularly untreated steel.
OBJECTS OF THE INVENTION AND GENER~L DESCRIPTION
'I It has now been found that the above-noted disadvantages with
2- respect to leveling and lack of adhesion can be eliminated by emulsifying the water-soluble cationic binders with select di- and/or triurethanes. It has been found that not only is the leveling and adhesion characteristics of the binders improved by emulsification with the select di- or triurethanes, but surprisingly the emulsions obtained, without use of additional emulsifiers, i have excellent stability even when water diluted for use in coating composi-', tions to be applied at the cathode of an electrodeposition process. The added select di- or triurethanes, however, exert a favorable influence on the viseosity of the coating compositions and on the curing characteristics of films deposited from the coating compositions, namely, enhanced corrosion re-; 30 sistance, in addition to the improved leveling characteristic and adhesion of the film to diverse substrates. Furthermore, the addition of the non-- ' :
~`~
water-soluble, fatty acid modified polyester resins permits regulation of the deposition equivalent which in turn influences the formation of the film on deposition.
The present inv0ntion provides a coating composition which is ::
; cathodically deposited when used in an electrodeposition process comprising ;
as the coating binder an aqueous emulsion of (I) 98 - 50 % by weight of at least one selfcrosslinking cationic binder based on a modified epoxy compound from the group comprising: ~ :
(A) the reaction products of diepoxy compounds with alpha,beta- :
; 10 unsaturated acids and, optionally, long chain fatty acids, and : basic monoisocyanates;
(B) reaction products of diepoxy compounds with monoamines and, -optionally, fatty acids, and unsaturated monoisocyanates;
(C) two moles of a diepoxy compound plus one mole of a primary-tertiary :
or secondary-secondary diamine plus two moles of an alpha,beta-unsaturated monocarboxylic acid and, optionally, an unsaturated fatty acid, plus an unsaturated monoisocyanate and ; (II) 2 - 50 % by weight of a urethane obtained by reacting one isocyanate group of a di- or triisocyanate with a hydroxy ethyl(meth)acrylate or a hydroxypropyl(~eth)acrylate, and the remaining isocyanate groups with a saturated or unsaturated aliphatic monohydric alcohol with at least 6 carbon atoms or a monohydroxyalkoxy(meth)acrylate or a saturated or unsaturated aliphatic monocarboxylic acid with at least 6 carbon atoms.
i! The present invention also provides a process of preparation of . cathodically electrodepositable coating compositions which comprises emulsifying :~
.. (I) 98 - 50 % by weight of at least one selfcrosslinking cationic ~: binder based on a modified epoxy compound from the group comprising:
(A) the reaction products of diepoxy compounds with alpha,beta-:~' 30 unsaturated acids and, optionally, long chain fatty acids, and basic -I monoisocyanates;
:'`
. ~
' ~Uii .
:
` 1085079 ~B) reaction products of diepoxy compounds with monoamines and, .
optionally, fatty acids, and unsaturated monoisocyanates;
~C) two moles of a diepoxy compound plus one mole of a primary-tertiary or seconda~y-secondary diamine plus two moles of an alpha,beta-unsaturated monocarboxylic acid and, optionally, an unsaturated fatty acid, plus an unsaturated monoisocyanate and ~ II) 2 - 50 % by weight of a urethane obtained by reacting one isocyanate group of a di- or triisocyanate with a hydroxy ethyl~meth)acrylate or a hydroxypropyl(meth)acrylate, and the remaining isocyanate groups with a saturated or unsaturated aliphatic monohydric alcohol with at least 6 carbon atoms or a monohydroxyalkoxy(meth)acrylate or a saturated or unsaturated aliphatic monocarboxylic acid with at least 6 carbon atoms.
The cathodically depositable binders for coating compositions which can be emulsified with the non-water-soluble, di- or triurethanes are self-crosslinking binders based on modified epoxy compounds~ and particularly binders comprising -(A) the reaction products of diepoxy compounds with alpha,beta-unsaturated acids and, optionally, long chain fatty acids, ant basic monoisocyanates;
(B) reaction products of diepoxy compounds with mono-amines and, optionally, fatty acids, and unsaturated monoisocyanates; and (C) two moles of a diepoxy compound plus one mole of a primary-tertiary or secondary-secondary diamine plus two moles of an alpha,beta-unsaturated monocarboxylic acid and, optionally, an unsaturated fatty acid, plus an unsaturated monoisocyanate.
The di- or triurethanes emulsified in or with the water-soluble cationic resins as hereinbefore described have the general formula -Rl - C - MH - R - (NH - C ~ ~ )n wherein R represents an aromatic (preferably phenyl ornaphthyl),cycloaliphatic, or aliphatic (preferably of 2 to 10 carbon atoms) hydrocarbon radical;
Rl stands for a hydroxyethyl(meth)acrylate or a hydroxypropyl-, --~ 1227/1310 1085079 (meth)acrylate radical; ~2 is the radical of a saturated and/or unsaturated aliphatic monoalcohol with at least 6 carbon atoms and/or an alkyl or aLkylene radical with at least 6 carbon atoms, and n is an integer of 1 or 2.
The compounds are prepared by stepwise or simultaneous reaction of 1 mole of a corresponding di- or triisocyanate with 1 mole of hydroxyethyl acrylate or hydroxypropyl acrylate or of the corresponding methacrylates and 1 or 2 moles of the longer chain saturated or unsaturated monoalcohol or a cor-responding monocarboxylic acid at 20 to 80 C., optionally in the presence of an isocyanate inert solvent. Suitable di- or triisocyanates are, e.g., aromatic isocyanates, such as 2, 4- or 2, 6-toluene diisocyanate; 4, 4'-diphenylmethane diisocyanate; or cycloaliphatic isocyanates such as iso-phorone diisocyanate and cyclohexane-1,4-diisocyanate as well as aliphatic isocyanates such as trimethyl -hexamethylene-1, 6-diisocyanate and trishexa-methylene-triisocyanate. As used herein, the di- and triisocyanates~are at , 15 times referred to as polyisocyanates. Any long chain monoalcohol with at least 6 carbon atoms in the chain is suitable. Saturated alcohols in this ' group include the n-alcanols, particularly saturated fatty alcohols. Suitable unsaturated alcohols include, on the one hand, those with an alpha,beta-ethylenic double bond, such as esters of acrylic and methacrylic acid with a di- or triol or a polyglycol, and, on the other hand, unsaturated fatty alcohols. Furthermore, saturated or unsaturated fatty acids with at least 6 carbon atoms are suitable, such as pelargonic acid, lauric acid, stearic acid, oleic acid, linolenic acid, as well as mixtures of these acids as are obtained from the natural olls. During the reaction of fatty acids with the isocyanate, as is known, CO2 is set free.
The basic groups (amine groups) of the cationic components are ~~ - 1227 / 1310 partially or totally neutralized with organic and/or inorganic acids, e.g., formic acid, acetic acid, lactic acid, phosphoric acid, etc. The degree of neutralization depends upon the properties of the binder employed in each individual case. In general, sufficient acid is added to provide dispersion or dilution with water of the coating composition at a pH-value of from 4 to 9, preferably from 6 to 8.
The combination, admixing, or emulsifying of the components advantageously is carried out in order that the binders are homogenized thoroughly, optionally at elevated temperature, prior to the addition of water. Subsequently, the neutralizing agent is stirred in and the batch is ; diluted with water to application viscosity, usually after milling the resin blend together with pigments and extenders.
The concentration of the binder in water depends upon the para-meters of the electrodeposition process and may range fror~ 3 to 30 percent by weight, preferably from 5 to 15 percent by weight. Upon electrodeposi-tion, the binder of the invention as a vehicle of the aqueous coating composi-tion is wired to a conductive anode and cathode, the surface of the cathode being coated with the coating composition. The conductive substrates to be !
coated may be any of a variety of materials, and particularly metals such as steel, alu~nnurn, copper, or the like. Other metalized materials or materials rendered conductive through a conductive coating can be employed.
After deposition, the coating is cured at a stoving temperature of from about 130 to 200 C., preferably 150 to 180 C~ ~ for from about 5 to 30 minutes, preferab`ly 10 to 25 minutes.
The following examples illustrate the invention without limiting its scope.
~ 1 227 / 1 3 10 i 1085079 Water-Dilutable Cationic Resins I - III
The composition of the water-dilutable cationic resins are tabu-lated in Table 1 wherein all quantities are parts by weight. The resins were prepared as follows:
S A reaction vessel is equipped with stirrer, addition funnel, thermometer, and reflux condensor. The epoxy compound listed in Table 1, solubilized in an isocyanate inert solvent such as monoethylene glycol mono-ethylether acetate (ethylglycol acetate), is charged to the vessel; and, upon addition of hydroquinone as an inhibitor, if desired, the monocarboxylic acid 10 is added at elevated temperature. The reaction is carried to an acid value of below 5 mg KOH/g at 100 to 110C. Epoxy resins with low melting points can be reacted without addition of solvents. The reaction product is mixed with the basic monoisocyanate intermediate designated in the table and is ;
reacted at 60 to 70 C. to an NCO-value of 0. Access of moixture is avoided 15 during the reaction.
.
-~- 1227/1310 . , TA BLE
Epoxy Resin, Solvent, Monocarbo~ylic Basic Inhibitor __ Acids Monoisocyanates 1000 EPH B 224 TFS 832 B (iso) 560 AEGLLAC 86. 5 ACS
0.2 HY
II 1000 EPH B -144 ACS 705 B ~iso) 0.2 HY
III 520 EPH C 564 HE 750 A (iso) 0.3 HY
.. . .
,~ EPH B - a solid epoxy resin based on Bisphenol A having a melting range of 65 to 75C., an epoxy-equivalent of 485 - 510, and a molecular weight of about 1000.
. .
EPH C - a highly viscous epoxy resin based on Bisphènol A having an epoxy-equivalent of about 260.
A (iso) - reaction product of 1 mole toluene diisocyanate and 1 mole ;;
dimethyl ethanolamine, 70 percent, dissolved in ethyl-acetate.
B (iso) - -reaction product of 1 mole toluene diisocyanate and 1 mole diethylethanolarnine, 70 percent, dissolved in ethyl-acetate.
HY - hydroquinone (an inhibitor).
TFS - tall oil fatty acids (with about 2 percent rosin acids).
', ~ ACS - acrylic acid.
'~
HE _ semi-ester of tetrahydrophthalic acid and hydroxyethyl methacrylate.
AEGLAC - ethylene glycol monoethylether acetate.
., :-. j .
~ 1227/1310 Non-Water-Soluble Urethane Compounds Compound A: 174 g (1 mole) toluene diisocyanate is charged to a reaction vessel and reacted at 25 to 40 C. with 130 g hydroxyethyl-methacrylate and 350 g tetrapropylene glycol monomethacrylate, the latter being added dropwise and simultaneously. The batch is finally heated to 70 C. and reacted to an NCO-value of 0.
Cornpound B: Analogous to Compound A, 174 g of toluene di-isocyanate are reacted with 130 g of hydroxypropylacrylate and 266 g of linoleyl alcohol.
Compound C: Analogous to Compound A, 504 g of tris-hexa-methylene triisocyanate are reacted with 130 g of hydroxypropylacrylate and 532 g of oleyl alcohol.
Compound D: To 174 g (1 mole) of toluene diisocyanateJ 280 g linseed oil fatty acids are added at 80C., and, after cooling the batch to 40~C., 130 g of hydroxyethylmethacrylate are added dropwise. The batch is reheated to 70C. and reacted to an NCO-value of 0.
, .
E:xamples 1 - 4 In accordance with Table 2, homogeneous blends of the above-described water-soluble cationic resins and non-water-soluble urethanes 20 were prepared. Each ioo parts (resin solids) of the resin blends were ; thereafter milled on a triple roll mill together with 22 parts aluminum silicate pigment, 2 parts carbon black, and 1 part lead chromate. The paint pastes were mixed with the listed neutralizing agents and diluted with deionized water to a solids content of 12.5 percent by weight. Electro-25 deposition of the blends was carried out in a plastic tank with a bath tem-perature of 30C. and a deposition time of 60 C. The anode was a carbon ' . . : . .
' .. . . :
plate. The cathodically wired suhstrate was untreated steel panels or iron phosphated steel plates as designated in Table 3. The deposited films were cured at 180 C. for 30 minutes in an air circulation oven.
Cationic Resin Polyester Resin Neutralizing Agent Example I II III A B C D ES MS
- - 30 - - - 0. 08 2 - 95 - - 5 - - - 0. 08
~`~
water-soluble, fatty acid modified polyester resins permits regulation of the deposition equivalent which in turn influences the formation of the film on deposition.
The present inv0ntion provides a coating composition which is ::
; cathodically deposited when used in an electrodeposition process comprising ;
as the coating binder an aqueous emulsion of (I) 98 - 50 % by weight of at least one selfcrosslinking cationic binder based on a modified epoxy compound from the group comprising: ~ :
(A) the reaction products of diepoxy compounds with alpha,beta- :
; 10 unsaturated acids and, optionally, long chain fatty acids, and : basic monoisocyanates;
(B) reaction products of diepoxy compounds with monoamines and, -optionally, fatty acids, and unsaturated monoisocyanates;
(C) two moles of a diepoxy compound plus one mole of a primary-tertiary :
or secondary-secondary diamine plus two moles of an alpha,beta-unsaturated monocarboxylic acid and, optionally, an unsaturated fatty acid, plus an unsaturated monoisocyanate and ; (II) 2 - 50 % by weight of a urethane obtained by reacting one isocyanate group of a di- or triisocyanate with a hydroxy ethyl(meth)acrylate or a hydroxypropyl(~eth)acrylate, and the remaining isocyanate groups with a saturated or unsaturated aliphatic monohydric alcohol with at least 6 carbon atoms or a monohydroxyalkoxy(meth)acrylate or a saturated or unsaturated aliphatic monocarboxylic acid with at least 6 carbon atoms.
i! The present invention also provides a process of preparation of . cathodically electrodepositable coating compositions which comprises emulsifying :~
.. (I) 98 - 50 % by weight of at least one selfcrosslinking cationic ~: binder based on a modified epoxy compound from the group comprising:
(A) the reaction products of diepoxy compounds with alpha,beta-:~' 30 unsaturated acids and, optionally, long chain fatty acids, and basic -I monoisocyanates;
:'`
. ~
' ~Uii .
:
` 1085079 ~B) reaction products of diepoxy compounds with monoamines and, .
optionally, fatty acids, and unsaturated monoisocyanates;
~C) two moles of a diepoxy compound plus one mole of a primary-tertiary or seconda~y-secondary diamine plus two moles of an alpha,beta-unsaturated monocarboxylic acid and, optionally, an unsaturated fatty acid, plus an unsaturated monoisocyanate and ~ II) 2 - 50 % by weight of a urethane obtained by reacting one isocyanate group of a di- or triisocyanate with a hydroxy ethyl~meth)acrylate or a hydroxypropyl(meth)acrylate, and the remaining isocyanate groups with a saturated or unsaturated aliphatic monohydric alcohol with at least 6 carbon atoms or a monohydroxyalkoxy(meth)acrylate or a saturated or unsaturated aliphatic monocarboxylic acid with at least 6 carbon atoms.
The cathodically depositable binders for coating compositions which can be emulsified with the non-water-soluble, di- or triurethanes are self-crosslinking binders based on modified epoxy compounds~ and particularly binders comprising -(A) the reaction products of diepoxy compounds with alpha,beta-unsaturated acids and, optionally, long chain fatty acids, ant basic monoisocyanates;
(B) reaction products of diepoxy compounds with mono-amines and, optionally, fatty acids, and unsaturated monoisocyanates; and (C) two moles of a diepoxy compound plus one mole of a primary-tertiary or secondary-secondary diamine plus two moles of an alpha,beta-unsaturated monocarboxylic acid and, optionally, an unsaturated fatty acid, plus an unsaturated monoisocyanate.
The di- or triurethanes emulsified in or with the water-soluble cationic resins as hereinbefore described have the general formula -Rl - C - MH - R - (NH - C ~ ~ )n wherein R represents an aromatic (preferably phenyl ornaphthyl),cycloaliphatic, or aliphatic (preferably of 2 to 10 carbon atoms) hydrocarbon radical;
Rl stands for a hydroxyethyl(meth)acrylate or a hydroxypropyl-, --~ 1227/1310 1085079 (meth)acrylate radical; ~2 is the radical of a saturated and/or unsaturated aliphatic monoalcohol with at least 6 carbon atoms and/or an alkyl or aLkylene radical with at least 6 carbon atoms, and n is an integer of 1 or 2.
The compounds are prepared by stepwise or simultaneous reaction of 1 mole of a corresponding di- or triisocyanate with 1 mole of hydroxyethyl acrylate or hydroxypropyl acrylate or of the corresponding methacrylates and 1 or 2 moles of the longer chain saturated or unsaturated monoalcohol or a cor-responding monocarboxylic acid at 20 to 80 C., optionally in the presence of an isocyanate inert solvent. Suitable di- or triisocyanates are, e.g., aromatic isocyanates, such as 2, 4- or 2, 6-toluene diisocyanate; 4, 4'-diphenylmethane diisocyanate; or cycloaliphatic isocyanates such as iso-phorone diisocyanate and cyclohexane-1,4-diisocyanate as well as aliphatic isocyanates such as trimethyl -hexamethylene-1, 6-diisocyanate and trishexa-methylene-triisocyanate. As used herein, the di- and triisocyanates~are at , 15 times referred to as polyisocyanates. Any long chain monoalcohol with at least 6 carbon atoms in the chain is suitable. Saturated alcohols in this ' group include the n-alcanols, particularly saturated fatty alcohols. Suitable unsaturated alcohols include, on the one hand, those with an alpha,beta-ethylenic double bond, such as esters of acrylic and methacrylic acid with a di- or triol or a polyglycol, and, on the other hand, unsaturated fatty alcohols. Furthermore, saturated or unsaturated fatty acids with at least 6 carbon atoms are suitable, such as pelargonic acid, lauric acid, stearic acid, oleic acid, linolenic acid, as well as mixtures of these acids as are obtained from the natural olls. During the reaction of fatty acids with the isocyanate, as is known, CO2 is set free.
The basic groups (amine groups) of the cationic components are ~~ - 1227 / 1310 partially or totally neutralized with organic and/or inorganic acids, e.g., formic acid, acetic acid, lactic acid, phosphoric acid, etc. The degree of neutralization depends upon the properties of the binder employed in each individual case. In general, sufficient acid is added to provide dispersion or dilution with water of the coating composition at a pH-value of from 4 to 9, preferably from 6 to 8.
The combination, admixing, or emulsifying of the components advantageously is carried out in order that the binders are homogenized thoroughly, optionally at elevated temperature, prior to the addition of water. Subsequently, the neutralizing agent is stirred in and the batch is ; diluted with water to application viscosity, usually after milling the resin blend together with pigments and extenders.
The concentration of the binder in water depends upon the para-meters of the electrodeposition process and may range fror~ 3 to 30 percent by weight, preferably from 5 to 15 percent by weight. Upon electrodeposi-tion, the binder of the invention as a vehicle of the aqueous coating composi-tion is wired to a conductive anode and cathode, the surface of the cathode being coated with the coating composition. The conductive substrates to be !
coated may be any of a variety of materials, and particularly metals such as steel, alu~nnurn, copper, or the like. Other metalized materials or materials rendered conductive through a conductive coating can be employed.
After deposition, the coating is cured at a stoving temperature of from about 130 to 200 C., preferably 150 to 180 C~ ~ for from about 5 to 30 minutes, preferab`ly 10 to 25 minutes.
The following examples illustrate the invention without limiting its scope.
~ 1 227 / 1 3 10 i 1085079 Water-Dilutable Cationic Resins I - III
The composition of the water-dilutable cationic resins are tabu-lated in Table 1 wherein all quantities are parts by weight. The resins were prepared as follows:
S A reaction vessel is equipped with stirrer, addition funnel, thermometer, and reflux condensor. The epoxy compound listed in Table 1, solubilized in an isocyanate inert solvent such as monoethylene glycol mono-ethylether acetate (ethylglycol acetate), is charged to the vessel; and, upon addition of hydroquinone as an inhibitor, if desired, the monocarboxylic acid 10 is added at elevated temperature. The reaction is carried to an acid value of below 5 mg KOH/g at 100 to 110C. Epoxy resins with low melting points can be reacted without addition of solvents. The reaction product is mixed with the basic monoisocyanate intermediate designated in the table and is ;
reacted at 60 to 70 C. to an NCO-value of 0. Access of moixture is avoided 15 during the reaction.
.
-~- 1227/1310 . , TA BLE
Epoxy Resin, Solvent, Monocarbo~ylic Basic Inhibitor __ Acids Monoisocyanates 1000 EPH B 224 TFS 832 B (iso) 560 AEGLLAC 86. 5 ACS
0.2 HY
II 1000 EPH B -144 ACS 705 B ~iso) 0.2 HY
III 520 EPH C 564 HE 750 A (iso) 0.3 HY
.. . .
,~ EPH B - a solid epoxy resin based on Bisphenol A having a melting range of 65 to 75C., an epoxy-equivalent of 485 - 510, and a molecular weight of about 1000.
. .
EPH C - a highly viscous epoxy resin based on Bisphènol A having an epoxy-equivalent of about 260.
A (iso) - reaction product of 1 mole toluene diisocyanate and 1 mole ;;
dimethyl ethanolamine, 70 percent, dissolved in ethyl-acetate.
B (iso) - -reaction product of 1 mole toluene diisocyanate and 1 mole diethylethanolarnine, 70 percent, dissolved in ethyl-acetate.
HY - hydroquinone (an inhibitor).
TFS - tall oil fatty acids (with about 2 percent rosin acids).
', ~ ACS - acrylic acid.
'~
HE _ semi-ester of tetrahydrophthalic acid and hydroxyethyl methacrylate.
AEGLAC - ethylene glycol monoethylether acetate.
., :-. j .
~ 1227/1310 Non-Water-Soluble Urethane Compounds Compound A: 174 g (1 mole) toluene diisocyanate is charged to a reaction vessel and reacted at 25 to 40 C. with 130 g hydroxyethyl-methacrylate and 350 g tetrapropylene glycol monomethacrylate, the latter being added dropwise and simultaneously. The batch is finally heated to 70 C. and reacted to an NCO-value of 0.
Cornpound B: Analogous to Compound A, 174 g of toluene di-isocyanate are reacted with 130 g of hydroxypropylacrylate and 266 g of linoleyl alcohol.
Compound C: Analogous to Compound A, 504 g of tris-hexa-methylene triisocyanate are reacted with 130 g of hydroxypropylacrylate and 532 g of oleyl alcohol.
Compound D: To 174 g (1 mole) of toluene diisocyanateJ 280 g linseed oil fatty acids are added at 80C., and, after cooling the batch to 40~C., 130 g of hydroxyethylmethacrylate are added dropwise. The batch is reheated to 70C. and reacted to an NCO-value of 0.
, .
E:xamples 1 - 4 In accordance with Table 2, homogeneous blends of the above-described water-soluble cationic resins and non-water-soluble urethanes 20 were prepared. Each ioo parts (resin solids) of the resin blends were ; thereafter milled on a triple roll mill together with 22 parts aluminum silicate pigment, 2 parts carbon black, and 1 part lead chromate. The paint pastes were mixed with the listed neutralizing agents and diluted with deionized water to a solids content of 12.5 percent by weight. Electro-25 deposition of the blends was carried out in a plastic tank with a bath tem-perature of 30C. and a deposition time of 60 C. The anode was a carbon ' . . : . .
' .. . . :
plate. The cathodically wired suhstrate was untreated steel panels or iron phosphated steel plates as designated in Table 3. The deposited films were cured at 180 C. for 30 minutes in an air circulation oven.
Cationic Resin Polyester Resin Neutralizing Agent Example I II III A B C D ES MS
- - 30 - - - 0. 08 2 - 95 - - 5 - - - 0. 08
3 - - 82 - - 18 - 0. 08
4 - 78 - - - - 22 0~ 08 The resin quantities referred to are based on 100% resin sdids.
The quantity of neutralizing agent is in moles for 100 g resin solids.
ES - acetic acid.
MS - lactic acid, ;
Deposition conditions and test results are as listed in Table 3 as follow9:
.
;'. . " -.: . ~ .
.
'~ 1227/1310 _ _ .
u~Untreated Steel Iron-Phosphated Steel 120 201 7.1 250 1-2 ~ 250 2 200 201-2 4.3 275 1 280 i' 1 3 140 221-2 6.6 255 2 250 !
4 180 211-2 5.4 250 1-2 255 , surface evaluation - I = excellent 2 = slightly wavy 10 salt spray evaluation - 1 = no visible attack 2 = slight corrosion underneath Adhesion in all cases is from Gt O B to 1 B according to DIN 53 151, which is excellent.
In the above illustrative examples the cationic water-solubIe 15 resin and non-water-soluble urethane component can be modified and/or the amounts varied within the bounds herein designated with enhanced results being obtainable. Additionally. the cationic water-soluble resin can be replaced with other cationic water-soluble resins which are of the self-crosslinl~ing type and which are based on a modified diepoxide system.
20 These and other modifications being within the ability of one skilled in the art are within the scope OI the present invention.
-, , , . ~ , ~
.
The quantity of neutralizing agent is in moles for 100 g resin solids.
ES - acetic acid.
MS - lactic acid, ;
Deposition conditions and test results are as listed in Table 3 as follow9:
.
;'. . " -.: . ~ .
.
'~ 1227/1310 _ _ .
u~Untreated Steel Iron-Phosphated Steel 120 201 7.1 250 1-2 ~ 250 2 200 201-2 4.3 275 1 280 i' 1 3 140 221-2 6.6 255 2 250 !
4 180 211-2 5.4 250 1-2 255 , surface evaluation - I = excellent 2 = slightly wavy 10 salt spray evaluation - 1 = no visible attack 2 = slight corrosion underneath Adhesion in all cases is from Gt O B to 1 B according to DIN 53 151, which is excellent.
In the above illustrative examples the cationic water-solubIe 15 resin and non-water-soluble urethane component can be modified and/or the amounts varied within the bounds herein designated with enhanced results being obtainable. Additionally. the cationic water-soluble resin can be replaced with other cationic water-soluble resins which are of the self-crosslinl~ing type and which are based on a modified diepoxide system.
20 These and other modifications being within the ability of one skilled in the art are within the scope OI the present invention.
-, , , . ~ , ~
.
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A coating composition which is cathodically deposited when used in an electrodeposition process comprising as the coating binder an aqueous emulsion of (I) 98 - 50 % by weight of at least one selfcrosslinking cationic binder based on a modified epoxy compound from the group comprising:
(A) the reaction products of diepoxy compounds with alpha,beta-unsaturated acids and, optionally, long chain fatty acids, and basic monoisocyanates;
(B) reaction products of diepoxy compounds with mono-amines and, optionally, fatty acids, and unsaturated monoisocyanates;
(C) two moles of a diepoxy compound plus one mole of a primary-tertiary or secondary-secondary diamine plus two moles of an alpha, beta-unsaturated monocarboxylic acid and, optionally, an un-saturated fatty acid, plus an unsaturated monoisocyanate and (II) 2 - 50 % by weight of a urethane obtained by reacting one isocyanate group of a di- or triisocyanate with a hydroxy ethyl(meth) acrylate or a hydroxypropyl(meth)acrylate, and the remaining isocyanate groups with a saturated or unsaturated aliphatic monohydric alcohol with at least 6 carbon atoms or a monohydroxyalkoxy(meth)acrylate or a saturated or unsaturated aliphatic monocarboxylic acid with at least 6 carbon atoms.
(A) the reaction products of diepoxy compounds with alpha,beta-unsaturated acids and, optionally, long chain fatty acids, and basic monoisocyanates;
(B) reaction products of diepoxy compounds with mono-amines and, optionally, fatty acids, and unsaturated monoisocyanates;
(C) two moles of a diepoxy compound plus one mole of a primary-tertiary or secondary-secondary diamine plus two moles of an alpha, beta-unsaturated monocarboxylic acid and, optionally, an un-saturated fatty acid, plus an unsaturated monoisocyanate and (II) 2 - 50 % by weight of a urethane obtained by reacting one isocyanate group of a di- or triisocyanate with a hydroxy ethyl(meth) acrylate or a hydroxypropyl(meth)acrylate, and the remaining isocyanate groups with a saturated or unsaturated aliphatic monohydric alcohol with at least 6 carbon atoms or a monohydroxyalkoxy(meth)acrylate or a saturated or unsaturated aliphatic monocarboxylic acid with at least 6 carbon atoms.
2. The coating composition of claim 1 wherein the aqueous emulsion is from 95 to 70 % by weight of the water-soluble resin (I) and from 5 to 30 %
by weight of the urethane (II).
by weight of the urethane (II).
3. The coating composition of claim 1 including at least one member of the group consisting of pigments, extenders, and hardening components
4. The coating composition of claim 1 wherein the urethane is the reaction product of a diepoxide with alpha,beta-unsaturated acids and a basic monoisocyanate.
5. The coating composition of claim 1 wherein the urethane is the reaction product of a diepoxide with a mono-amine and an unsaturated monoisocyanate.
6. The coating composition of claim 1 wherein the urethane is the reaction product of 2 moles of a diepoxy compound, 1 mole of a primary-tertiary or secondary-secondary diamine, 2 moles of an alpha,beta-unsaturated monocarboxylic acid, and an unsaturated monoisocyanate.
7. A process of preparation of cathodically electrodepositable coating compositions which comprises emulsifying (I) 98 - 50 % by weight of at least one selfcrosslinking cationic binder based on a modified epoxy compound from the group comprising:
(A) the reaction products of diepoxy compounds with alpha,beta-unsaturated acids and, optionally, long chain fatty acids, and basic monoisocyanates;
(B) reaction products of diepoxy compounds with monoamines and, optionally, fatty acids, and unsaturated monoisocyanates;
(C) two moles of a diepoxy compound plus one mole of a primary-tertiary or secondary-secondary diamine plus two moles of an alpha, beta-unsaturated monocarboxylic acid and, optionally, an un-saturated fatty acid, plus an unsaturated monoisocyanate and (II) 2 - 50 % by weight of a urethane obtained by reacting one isocyanate group of a di- or triisocyanate with a hydroxy ethyl(meth)acrylate or a hydroxypropyl(meth)acrylate, and the remaining isocyanate groups with a saturated or unsaturated aliphatic monohydric alcohol with at least 6 carbon atoms or a monohydroxyalkoxy(meth)acrylate or a saturated or unsaturated aliphatic monocarboxylic acid with at least 6 carbon atoms.
(A) the reaction products of diepoxy compounds with alpha,beta-unsaturated acids and, optionally, long chain fatty acids, and basic monoisocyanates;
(B) reaction products of diepoxy compounds with monoamines and, optionally, fatty acids, and unsaturated monoisocyanates;
(C) two moles of a diepoxy compound plus one mole of a primary-tertiary or secondary-secondary diamine plus two moles of an alpha, beta-unsaturated monocarboxylic acid and, optionally, an un-saturated fatty acid, plus an unsaturated monoisocyanate and (II) 2 - 50 % by weight of a urethane obtained by reacting one isocyanate group of a di- or triisocyanate with a hydroxy ethyl(meth)acrylate or a hydroxypropyl(meth)acrylate, and the remaining isocyanate groups with a saturated or unsaturated aliphatic monohydric alcohol with at least 6 carbon atoms or a monohydroxyalkoxy(meth)acrylate or a saturated or unsaturated aliphatic monocarboxylic acid with at least 6 carbon atoms.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ATA8727/76 | 1976-11-24 | ||
| AT872776A AT345407B (en) | 1976-11-24 | 1976-11-24 | CATHODICALLY SEPARABLE COATING AGENT FOR THE ELECTRIC DIP PAINTING PROCESS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1085079A true CA1085079A (en) | 1980-09-02 |
Family
ID=3608032
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA291,630A Expired CA1085079A (en) | 1976-11-24 | 1977-11-24 | Cathodically depositable compositions for electrodeposition |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5388830A (en) |
| AT (1) | AT345407B (en) |
| CA (1) | CA1085079A (en) |
| DE (1) | DE2752255A1 (en) |
| ES (1) | ES464315A1 (en) |
| FR (1) | FR2372215A1 (en) |
| GB (1) | GB1545390A (en) |
| IT (1) | IT1088891B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5813781A (en) * | 1981-07-14 | 1983-01-26 | 東レ株式会社 | Carbon fiber excellent in anti-friction property |
| DE3311512A1 (en) * | 1983-03-30 | 1984-10-04 | Basf Farben + Fasern Ag, 2000 Hamburg | BINDING AGENT FOR CATHODIC ELECTRIC DIP PAINTING |
| DE3311513A1 (en) * | 1983-03-30 | 1984-10-04 | Basf Farben + Fasern Ag, 2000 Hamburg | HEAT-CURABLE COATING AGENTS AND THEIR USE |
| GB8312770D0 (en) * | 1983-05-10 | 1983-06-15 | Albright & Wilson | Resin deposition |
| US4581111A (en) | 1984-03-28 | 1986-04-08 | Ppg Industries, Inc. | Treatment of ultrafiltrate by electrodialysis |
| JPH0284469A (en) * | 1988-06-10 | 1990-03-26 | Kansai Paint Co Ltd | Cationic electrodeposition coating |
| US8945365B2 (en) | 2012-07-13 | 2015-02-03 | Ppg Industries Ohio, Inc. | Electrodepositable coating compositions exhibiting resistance to cratering |
-
1976
- 1976-11-24 AT AT872776A patent/AT345407B/en not_active IP Right Cessation
-
1977
- 1977-11-21 ES ES464315A patent/ES464315A1/en not_active Expired
- 1977-11-21 IT IT2985377A patent/IT1088891B/en active
- 1977-11-23 DE DE19772752255 patent/DE2752255A1/en active Granted
- 1977-11-23 FR FR7735223A patent/FR2372215A1/en active Granted
- 1977-11-24 JP JP14005277A patent/JPS5388830A/en active Granted
- 1977-11-24 CA CA291,630A patent/CA1085079A/en not_active Expired
- 1977-11-24 GB GB4898277A patent/GB1545390A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| IT1088891B (en) | 1985-06-10 |
| ES464315A1 (en) | 1979-06-16 |
| GB1545390A (en) | 1979-05-10 |
| JPS5523873B2 (en) | 1980-06-25 |
| DE2752255A1 (en) | 1978-06-01 |
| JPS5388830A (en) | 1978-08-04 |
| DE2752255C2 (en) | 1989-01-12 |
| FR2372215A1 (en) | 1978-06-23 |
| ATA872776A (en) | 1978-01-15 |
| AT345407B (en) | 1978-09-11 |
| FR2372215B1 (en) | 1983-04-01 |
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