CA2080144A1

CA2080144A1 - Synthetic resins

Info

Publication number: CA2080144A1
Application number: CA002080144A
Authority: CA
Inventors: Klaus Huemke; Gerhard Hoffmann; Dieter Faul; Ulrich Heimann; Dieter Ruehl
Original assignee: Individual
Current assignee: BASF Farben und Fasern AG
Priority date: 1991-10-12
Filing date: 1992-10-08
Publication date: 1993-04-13
Also published as: JP3327957B2; CN1072703A; KR930008077A; DE4133853A1; CN1035011C; ES2074785T3; KR100240903B1; JPH05279625A; DE59202149D1; ZA927773B; CN1065892C; EP0546269B1; EP0546269A1; DK0546269T3; CN1156163A; ATE122374T1

Abstract

- 20 - O.Z. 0062/02110 Abstract of the Disclosure: Synthetic resins contain, as essential components, A) an epoxide-carrying resin based on a1) a polyepoxide based on a polyhydric phenol, a2) a p o l y o x y a l k y l e n e p o l y o l , a polyoxyalkylenepolyepoxide or a mixture of these compounds, a3) a polyhydric phenol and a4) a phenolic compound which reacts monofunctionally toward epoxides and B) a sulfide.

Description

2~0~

O.Z. 0062/02110 Synthetic resins The present invention relates to plgment for-mulations which contaill, as essential components, I) A synthetic resin obtainable by reacting A) an epoxide-carrying resin based on al) a polyepoxide based on a polyhydric phenol, a2 ) a polyoxyalkylenepolyol, a polyoxy-alkylenepolyepoxide or a mixture of these compounds, a3) a polyhydric phenol, a4) a phenolic compound which reacts mono-functionally toward epoxides and B~ a sulfide and II) a pigment powder.
The present invention furthermore relates to a process for the preparation of these pigment formulations and to the use of the pigment formulations in electrocoa-ting baths.
For the cathodic electrocoating process, resin mixtures comprising a binder resin, a crosslinking component and a pigment formulation prepared from a resin having surfactant properties, a yrinding resin, and a pigment powder, are usually used.
Ammonium- and/or phosphonium-carrying binder resins which are based on polyepoxides based on polyhydric phenols, polyoxyalkylenepolyols a~d phenolic compounds which react monofunctionally toward epoxides are disclosed in EP-Bl-241 476~ It is recommended that these binder resins also be used as grinding resins in pigment formulations.
However, either these binder resins coagulate when they are milled with the pigment powder or the pigment formulations comprising these resins form a sediment in the electrocoating bath. Moreover, coatings which contain such pigment formulations have an unsatisfactory property spectrum.

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2~80~9~
- 2 - o.z. 0062/02110 It is an object of the present in~ention to provide pigment paste~ which have a low solvent content and a good overall spectrum of propertiPs, in particular little tendency to yellow and good processability.
We have found that this object i5 achieved by the pigment fo~mulations defined at the outset, which contain synthetic resin~ as essential component (I) and a pigment powder as essential component ~II). The synthetic resins (I) are obtainable by reacting an epoxide-carrying resin (component (A)) with a sulfide (component ~B)) in the presence of an acid.
Suitable components (A) are epoxide-carrying - resins, which may be present in the synthetic resins in amounts of from about 60 to absut 95, in particular from about 75 to ~5/ % by weight, based on the total weight of the synthetic resins. Their average mol~cular weights ~
may be from about 20Q to about 20,000, prefexably from about 500 to about 5,000. In general, the epoxide-carrying resins have an epoxide equivalent weight EEW of from 800 to 2,500, especially from 1,000 to 1,500.
The epoxide-carrying resins are polyepoxides based on polyhydric phenols, these basic building blocks being mixed or reacted with polyoxyalkylenepolyols, ~; polyoxyalkylenepolyepoxides or mixtures thereof. To obtain the desired epoxide equivalent weights, the mixtures or reaction products of the basic building blocks and the polyoxyalkylene components are reacted with polyhydric phenols and with phenolic compounds which react monofunctionally toward epoxides.
The polyepoxides based on polyhydric phenols (component (a1)) are generally present in the epoxide-carrying resin in amounts of from lO to 70f preferably from 30 to 7 0~ % by weight, based on the total weight of component (A). These basic building blocks generally have epoxide equivalent weights of from about 175 to about 1,000, preferably from about 180 to about 600. They can be obtained, for example, by reacting polyhydric phenols 208~
_ 3 ~ o.z. 0062/0~110 with an epihalohydrin, preferably epichlorohydrin.
Examples of polyhydric phenols are resorcinol, hydroquinone, 2/2-bi~-(4-hydroxyphenyl)-propane (bisphenol A), isomer mixtures of dihydroxydiphenylmethane (bisphenol F), 4,4'-dihydroxy-diphenylcyclohexane, 4,4' dihydroxy-3,3'-dimethyldi-phenylpropane, 4,4~-dihydroxydiphenyl, 4,4'-dihydroxy-benzophenone,l,1-bis-(4-hydroxyphenyl) ethane,l,1'-bis-(4-hydroxyphenyl)-isobutane, 2,2-b:is-(4-hydroxy-tert-butylphenyl)-propane, his-(2-hydroxynaphthyl)-methane, 1,5-dihydroxynaphthalene, tris-(4-hydroxyphenyl)-methane, and l,l'-bis-(4-hydroxyphenyl) ether. Of these bisphenol A is the preferred polyhydric phénol.
The suitable polyoxyalkylenepolyols and poly-oxyalkylenepolyepoxides may be linear or ~ranched. Bothpolyoxyalkylenepolyols and polyoxyalkylerlepolyepoxides which are composed of the same oxyalkylene groups and those which contain different oxyalkylene groups are suitable~ Polyoxyalkylenepolyols and polyoxyalkylenepoly-epoxides which caxry on average two terminal hydroxyl orepoxy groups per molecule are preferred. Polyoxyalkylene-polyepoxides can ba obtained, for example, by reacting a polyoxyalkylenol with an epihalohydrin. Examples of suitable polyoxyalkylenols are polyoxyethylene glycol, polyoxypropylene glycol, polyoxybutylene glycol, polyoxy-hexamethylene glycol, polyoxynonamethylene glycol, polyoxydecamethylene glycol and polyoxyethylene propylene glycol. Polyoxyalkylenepolyepoxides are preferably used as component (a2). The polyoxyalkylenepolyepoxides preferably used for the preparation of the novel pigment formulations are the diglycidyl ethers of polyoxyethylene glycol, polyoxypropylene glycol and polyoxybutylene glycol. However, mixtures of diferent polyoxyalkylenepolyol and polyoxyalkylenepolyepoxides may also be used.
The average molecular weights M~ of these polyoxy-alkylenepolyols and polyoxyalkylenepolyepoxides are, as 21~8~1~4 - 4 ~ O.Z. 0062/02110 a rule, from 200 to 20,000r preferably from 250 to 5,000, the particular hydroxyl or epoxide equivalent weight~
beiny in general from 150 to 5,000, preferably from 200 to 2,5Q0. As a rule, component (A) contains from 5 to 50, preferably from 10 to 30, ~ by weight, based on the total weight of the epoxide-carrying resin, of a polyoxy-alkylenepolyol, a polyoxyalkylenepolyepoxide or a mixture of these compounds.
In principle, all of the abovementioned polyhydric phenols are suitable for obtaining the epoxide equivalent weight, but hydroquinone, resorcinol, 1~5-dihydroxynaphthalene and ln particular hisphenol A are preferably used. These polyhydric phenols are present in component (A) preferably in amounts of from 10 to 30 ~ by weight, but also (component (a3)) in larger amounts, and in general in an amount of not more than 50 % by weight ox in a smaller amount d~wn to about 5 % by weight, based Oll the total weight of the epoxide-carrying resin.
The phenolic compound (component (a4~) which reacts monofunctionally towards epoxids~3 may be phenol which carries at least one nucleus substituent selected from the group consisting of the Cl-C20-alkoxy and C1-C20-alkyl radicals, where the alkyl radicals may be interrupted by one or more oxygen atoms. The nucleus substituents may be branched or linear, the latter being preferred. Compounds of the general formula I
(CE~2) nCH3 HO ~) \~J ( I ) R

where R = H, CH3 or CH2CH3 and independently thereof n is from 1 to 20, are particularly preferred.
Phenols in which R is H and n is from ~ to 18 have proven particularly advantageous. Particular examples amony these monoalkylphenols, whose alkyl substituents are preferably para to the OH group, are octylphenol, nonylphenol, decylphenol, undecylphenol, 2~801~

- 5 - o.z. ~062/02110 dodecylphenol and octadecylphenol. Mixtures of two or more different phenolic compounds ara preferably used.
Mixtures of two different monoalkylphenols which differ in their alkyl chain lengths n by at least 3 carbon atoms are partiularly preferred. Examples of such mixtures are pentylphenol and decylphenol, hexylphenol and nonyl-phenol, octylphenol and dodecylphenol, nonylphenol and dodecylphenol, and dodecylphenol and eicosylphenol~
mixtures of nonylphenol and doclecylphenol being preferred.
As a rule, component (A) contains from 0.5 to 30, preferably from 0.5 to 20, particularly preferably from 5 to 15, % by weight, based on the total weight of component (A), of the phenolic compound (a4) which reacts monofunctionally toward epoxides.
Compounds such as ethyltriphenylphosphonium bromide, triphenylphosphine, dimethylbenzylamine and triethylamine, which may be added in general in amounts up to 0.5 or preferably up to 0.3, ~ by weight, based on the total weight of component A, catalyze the reaction of components (al) to (a4) to ~ive the epoxide-carrying resins (component (A)).
According to the invention, the epoxide-carrying resins contain, as component ~B)~ a sulfide, which is also understood as being a mixture of different sulfides.
All sulfides which react with epoxy groups and have no groups which interfere in this reaction can be usedO For example, aliphatic sulfides, where the aliphatic radicals may be linear or branched1 mixed aliphatic-aromatic sulfides, aromatic sulfides, aralkyl sulfides or cyclic sulfides may be used. Examples of these sulfides are diethyl sulfide, dipropyl sulfide, dibutyl sulfide, dihexyl sulfide, ethyl phenyl sulfide, diphenyl sulfide, tetramethylene sulfide, pentamethylene sulfide, di-thydroxyethyl) sulfide, di-(hydroxypropyl) sulfide and di-(hydroxybutyl) sulfide. Dialkyl sulfides whose alkyl radicals are of 2 to 12 carbon atoms, in particular 2080~

- 6 - o.z. 0062/02110 di-C2-C5-alkyl sulfides, are preferred. Di~(hydroxyalkyl3 sulfides where each hydroxyalkyl radical is of 2 to 12 carbon atoms, in particular di-(hydroxyethyl) sulfide, are very particularly pre~erred. As a rule, the synthetic resins contain from 5 to 40, preferably from 5 to 30, in particular rom 5 to 15, ~ hy weightt based on the total weight of the synthetic resins, of component ~B). This amount corresponds to 0.5 - 1.5, particularly 0.5 to 1.0, sulfide molecules per epoxy group.
In addition to the essential components, the pisment formulations may also contain additives (component (C)) in amounts of in general not more than 10, in particular not more than 6, % by weight, based on the total weight of the pigment formulations. These include solvents or solvent mixtures which are inert toward epoxy groups, such as qlycol ethers, including propylene glycol phenyl ether and propylene glycol monomethyl ether~ However, the additives also include small amounts of polyuxethanes and polyvinyl ethers, which serve as leveling a~ents.
The sulfides are usually reacted with the epoxide-carrying resins in the presence of acids at from 50 to 150~C, if desired in the presence of additives, to give the synthetic resins (I).
All acids which are capable of forming tertiary sulfonium salts are suitable. Examples of these acids are hydrochloric acid, phosphoric acid and sulfuric acid.
Organic acids, such as formic acid, lactic acid, acetic acid, propionic acid, butyric acid and dimethylol-propionic acid, are preferred. Lactic acid is particularly preferred. In general, the molar ratio of acid to sulfide is from about 0.5:1 to about 1.2:1, in particular from about 0.6:1 to about 1.0:1.
The synthetic resins (I) can be dispersed in water. The aqueous dispersions usually contain from 1 to 60, preferably from 1 to 30, % by weight of synthetic resin.

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2~8~
- 7 - o.z~ 006~/02110 The ratîo of synthetic resin (I) to pi~nent powder (II) depends essentially on the type of piqment or pigment mixture and on its particle size. Synthetic resin:pigment powder ratios of 0.2:1, preferably rom 0.3~1, are possible. In addition to an aqueous dispersion (~) of the synthetic resin, which dispersion is present in an amount of in general from lO to 90, preferably from 20 to 80, % by weight of the pigment formulation, and the pigment powder, which as a rule is present in the formulation in an amount from lO to 90, preferably from 20 to 80, % by weight, up to lO % by weight of assistants may also be present in the pigment formulation. Examples of assistants ~) are fillers, dispersants, plasticizers and antifo~ms as well as acrylate-based pigment stabilizers.
- Conventional pigments (II) are, for example, iron oxides, lead oxides, strontium carbonate, carbon black, titanium dioxide, talc, barium sulfate, cadmium yellow, cadmium red, chromium yellow, phthalocyanine blue or 2a metallic pigments, such as aluminum flakes.
The pigment formulation is usually prepared by mixing the desired amount of dry piqment powder, which contains a pigment or a mixture of different pi~nents, with the aqueous dispersion of the synthetic resin and, if desired, the assistants and then milling the mixture until the solid particles have the desired particle size.
The solid particles are comminuted, as a rule, in ball mill5~ sand mills, Cowles dissolvers and continuous grinding apparatuses. After the grinding procedure, the particle size of the solid particles should be in the region of lO ~m or smaller. Finenesses of 3 ~m or less can be achieved by milling in the presence of glass, corundum, ceramic or zirconium dioxide beads.
The pigment for~nulations thus obtained can be mixed with surface coating binders. Particularly suitable binders are those which are compatible with the synthetic resins of the pisment pastes. These include in particular .

~08~1~4 - 8 - o.Z. 00~2/02110 water-dispersible epoxy resin based binders which can be used in electrocoating ~aths~ The ratios of pigment formulation to binder are usually from 0.25:1 to 1:1. The mixtures of pigment formulation and binder may contain crosslinking agents and assistants as further components.
The electrocoating is carriecl out in general by a known method, and all electrically conductive substrates, for example metals, such as steel~ copper or aluminum, can be coated. After the coating procedure, the coatings can be cured at elevated temperature~, which in general are dependent on the crosslirlking agent.
The novel pigment formulations have low solvent contents and may even be free of organic solvents. The coating~ which can be produced from the pi~ment 5 formulations exhibit only slight yellowing.
EXAMPLES
Ahbreviations EEW - Epoxide equivalent weight DE = demineralized Preparation of the novel synthetic resins K1 - K4 and of the comparative synthetic resins V3P and V3N

General method ;

The constituents of the epoxide-carrying resin (component ~A1) were initially taken in the stated amounts and heated to 110C until a clear solution had formed. The appropriate amount of catalyst was then added, with the result that the reaction temperature increased to above 150C. After the exothermic reaction had died down, the reaction temperature was kept at 130C
for about 90 minutes, until the desired epoxide equivalent weight had been reached. Thereafter, the mixture was either diluted with the stated amount of the organic solvent and cooled to 80C or cooled immediately to 80C. The stated amount of sulfide, tributylamine or ~o~
- 9 - 0.2. 0062~02110 dimethylethanolamine was then added dropwise in the coursa of 30 minutes. The acid or an acid/water mixture was then added rapidly at the same temperature. The reaction was allowed to continue until the acid number of the mixture h~d fallsn below 1~ The resulting product was processed either immediately or after the addition of further water.

Synthetic resin X1 Initially taken mixture:
103008 g of bisphenol A diglycidyl ether EEW 18a, M~
about 400 826 g of a diglycidyl ether o a polyethylene glycol having an M~ of ahout 400, EEW 200 1140 g of bisphenol A
589.5 g of dodecylphenol 495 g of nonylphenol Catalyst:
6.06g of ethyltriphenylphosphonium bromide EEW measured: 1080 606 g of 2-butoxyethanol 342.3 g of thiodiethanol : 758 g of 60 % strength lactic acid Vi ~C 08 ity at 75C. 2600 mPa.s Solids content: 89.3 %
Content of organic solvents: 7.8 %

Synthetic resin K2 Initially taken mixture:
2369 g of bisphenol A diglycidyl ether EEW 188, Mw of about 400 1115 g of diglycidyl ether of a propylene glycol haviny 20~V~4 - 10 - o.Z. 006~/02110 an MW of about 430, EEW 215 1140 g of bisphenol A
786 g of dodecylphenol 660 g of nonylphenol Catalyst 6.07 g of dimethylbenzylamine EEW measured: 1360 912 g of diethylene glycol 325,8 g of dibutyl sulfide 721 g of 60 ~ strength lactic aci.d 482 g of water Viscosity at 75C: 3280 mPa.s Solids content. 80.1 %
Content o~ organic solvents: 11.3 %

: 15 Synthetic resin X3 Initially taken mixture:
4061 g of bi~phenol A diglycidyl ether EEW 188, M~ of about 400 496 g of diglycidyl ether of a polybutylene glycol having an M~ of about 430, EEW 215 1140 g of bisphenol A
393 g of dodecylphenol 330 g of octylphenol Catalyst:
; 25 6.42 g of triethyla~ine EEW measured: 905 348 g of 1,2-dibutoxyethane 432.8 g of thiodiglycol 2~8Vl~

~ o.z. 006~/02110 958 g of 60 % strength lactic acid Viscosity at 75C~ 1800 mPa.s Solids content: 91.1 %
Content of organic solvents: 4.3 %

Synthetic re~in K4 Initially taken mixture:
1015.2 y of bisphenol A diglycidyl ether EEW 188, M~ of about 400 123.9 g of diglycidyl ether of a polyethylens glycol having an M~ of about 430, EEW 215 222.3 g of bisphenol A
99.2 g of nonylphenol 117.9 g of dodecylphenol Catalyst:
1.58 g of ethyltriphenylphosphonium bromide EEW measured: 558 : 189.4 g of thiodiethanol .:. 418O9 g of 60 % strength lactic acid 1178.6 g of DE Water Viscosity at 75C, 1680 mPa.s Solids content: 60.1 %
Content of organic solvents: 0 %

Comparative synthetic resin V3P
Initially taken mixture:
4061 g of bisphenol A diglycidyl ether E~W 188, MW about 496 g of a diglycidyl ether of a polytetrahydrofuran having an MW of about 400, EEW 215 1140 g of bisphenol A

- 12 - o.~. 0062/02110 393 g of dodecylphenol 330 g of octylphenol Catalyst .
6.42 g of triethylamine EEW measured: 910 348 g of butylglycol 755.6 g of tributylphosphine 958 g of 60 ~ strength lactic acid Viscosity at 75C: > 4000 mPa.~
The resin was further diluted with 710 g of butylglycol Viscosity at 75C: 2200 mPa.s Solids content: 84.3 %
Content of organic solvents: 11.5 %

Comparative synthetic resin V3N

Initially taken mixture~
4061 g of bisphenol A polyglycidylether EEW 188, M~ of about 400 496 g of diglycidyl ether of a polytetrahydrofuran having an M~ of about 400, EEW 215 1140 g of bisphe~ol A
393 g of dodecylphenol 330 g of octylphenol Catalyst:
6~42 g of triethylamine EEW measured: 908 348 g of butylglycol 315.7 g of dimethylethanolamine 958 g of 60 % strength lactic acid 208~4 13 - o.Z. 0062/02110 Viscosity at 75C: > 4000 mPa.s The resin wa.q further diluted with 1250 g of butylglycol Viscosity at 75C: 2160 mPa.s Solids content: 78.7 %
Content of organic solventso 17.2 %

Preparation of the pigment formulations 1 - 6 General method The particular synthetic resin was diluted with DE water to a solids content of from 30 to 35 ~O The stated amount of the pigments was then added. The m.ixture was milled in a stirred ball mill to a ~egman fineness o~ > 7.
Each synthetic resin was formulated with a lead-containing and a lead-free pigment mixture, as shown in Table I below.
Synthetic resins K1 to K4 and comparative ~- synthetic resin V3N could be processed to give the corresponding pigment formulations 1 to 4 and 5O The comparative synthetic resin V3P coagulated during milling : 20 to such an extent that it was not possible to prepare :~ pigment formulations.
,~
Preparation of the binder 246 g of hexamethylenediamine, 307 g of a dimeric fatty acid, 59 g of linoleic acid and 31 g of toluene were heated to 190C and the resulting water of reaction was distilled off azeotropically. The dilution was then effected with 73 g of toluene, and 4,1 g of hexamethylenediamine were added. The amine intermediate thus obkained had an amine number of 249 mg KOH/g. In a se~ond stirred vessel, 3061 g of bisphenol A diglycidyl ether (EEW about 485) were dissolved in 569 g of toluene and 534 g of isobutanol. 135 g of methylethanolamine were added at 55C. After an EEW of 835 had been reached, 2~8~
1~ - O.ZI 0~2/02110 65S g of the amine intermediate and 141 g of toluene were added. The reaction was then continued for 2 hours. The binder thus obtained had a solids content of 70~ and an amine number of 91 mg KOH/g.

Preparation oE the crosslinkiny agent 504 g of trimeri2ed hexamethylene diisocyanate were dissolved in 382 g of methyl isobutyl ketone. 388 g of dibutylamine were added dropwise at 70C while cooling. Stirring was continued until the isocyanate value had decreased to about zero. The crosslinking agent thus obtained had a solids content of about 70%.

Preparation of the binder/crosslinking agent dispersion 695 g of binder, 298 g of crosslinking agent and 16 g of glacial acetic acid were homogenized, after which ~E water was slowly added. The organic solvents present in the binder component and crosslinking component were then substantially distilled off under reduced pressure at 40-50C. A solids content of 35% was obtained by adding DE water~
~;
Preparation of the electrocoating baths E1 - E5 568 g of one of the ab~vementioned picJment formulations were added to 1964 g of the binder/crosslinking agent dispersion and stirring was carried out until the mixture was homogeneous. It was then filtered and made up to 5000 g with DE water. The solids content of the baths were about 20%. Coating of the metal sheets for testing the performance characteristics was carried out after the baths had been stirred for 7 days at room temperature.

208~14~
- 15 - ~.Z. 0062/02110 _ . ~
iq~ant Sy~thoti~ Piq~ant [ g j f orm~- roaln~ ~itaalum Lo~dChalk ~a~d W~or 5lation No . [ g I dioxid~ ~ black _ according to h~ invontion 1 0 . _ _ ~
1~ X~ 65.3 195.0 _ 4a.~ 5.5 251.0 lb ~ 65.3 220.0 23.1 _ 5.5 251.0 ~ X2 72.6 I~S.0 _ 4a.1 S.S 236.5 2b ~2 72.6 220.0 23.1 _ S.S 236.5 3a R3 63.9 lgS.0 _ 48.1 5.5 245.2 3~ R3 63.9 220.0 23.1 _ S .S 245.2 4~ ~4 96.8 l9S.0 _ 4~.1 S.S 212.3 4b ~4 96.8 220.0 ~ 3.1 _ , 212.3 for ccmpariDon with pig~or~t fo~mulation0 3a and 3b ~a ¦ V3N 174-o 1 l9S.0 ¦ _ 43.1 ¦ 5.5 ¦ 242.3 jb ¦ V3~ ¦ 7-,.0 ¦ 220.0 ¦ 23.1 1 _ ¦ S.S I 242.3 The amount of synthetic resin in the pigment formulations was 58.15 g in each case, based on solids.

Testing of performance characteristics Coatings were deposited from the electrocoating ~ baths at a voltage of from 220 to 350 V and at 27C onto : zinc-phosphated steel sheets measuring 190 x 105 ~m in the course of 2 minutes. Thereafter, the test specimens were washed *horoughly with DE water and the coatings : 35 were cured at 165C in the course of 20 minutes. The thickness of the coatings was from 16 to 26 ~m. The : results of the tests for the performance charac-teristics carried out on the coated metal sheets are shown in Table 2.

2~801~4 ~ 16 ~ O.Z. 0062/02110 T.ABLE 2 ._ _ ____ ~lact~o- Flgmont 1~ Loval- C~ CC~ Yellowi~g co~ting ~orm~l~tion t~l in~ ~ UH/S/~
cll~p~roior~ No. _ _ .. ~ __ ~caordlng ~o tho invoation 1 0 __ ___ _ . _ ~la la 310 3 20 2.1/1/5 2 ~lb lb 330 2 22 1.4/0/2 2 ~2~ 21 230 ~ 23 2.~/1/4 2 E2b 2~ 300 1 2~ 1.3/0/1 E3a 3~ 330 2 24 l.a/0/3 E3b 3b 350 1 25 1.1/0/2 E4~ 4a 310 2 22 2.0/0/3 : . 4b 4b 340 2 23 1.3/0/2 fo~ co~p~ri~on with ~3~ d i33b BS4l1 V3N ¦ 350 ~ 5 1 ~ ¦ 4 E5b2) V3N ~ _ I _ _ ~ . ~
U: Deposition voltage, measured in [V]
Leveling: Degrees of leveling 1 tvery good) - 5 (poor) CT: Coat thickness, measured in [~m]
CCT: 10 cycles in climatic cycling test according to VDA 621-415 UM: Undermigration at the crack according to DIN 50 021, measured in [mm]
S~ Surface rusting 0 (no rust) ~ 5 ~severely rusted) E: Edge rusting 0 (no rust) - 5 (severely rusted) Yellowing: Yellowness (no yellowing) - 5 (pronounced yellowing) To determine the degree of yellowing, a PVC strip was applied to each coated metal sheet, all the PVC strips being of the same size. The metal sheets thus prepared were sprayed with a white top coat which was then cured. The test sheets were ; 45 exposed to evaporating water for 8 days at 70C, it being possible for yellowing to occur in the region of the PVC strip.

-2 0 8 ~

- 17 - O~Z. 0062/0211~
From this electrocoatin~ dispersion it was possible to deposit on a very thin fllm, which exhibited pronounced yellowing.
2) Since this electrocoating di~persion . coagulated in the bath, rlo film deposition was possible at all.

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Claims

1. A pigment formulation containing, as essential components, I) A synthetic resin obtainable by reacting A) an epoxide-carrying resin based on a1) a polyepoxide based on a polyhydric phenol, a2) a polyoxyalkylenepolyol, a polyoxy-alkylenepolyepoxide or a mixture of these compounds, a3) a polyhydric phenol, a4) a phenolic compound which reacts mono-functionally toward epoxides and B) a sulfide and II) a pigment powder.

2. A pigment formulation as claimed in claim 1, in which the synthetic resins are obtainable from A) from 60 to 95% by weight of an epoxide-carrying resin based on a1) from 10 to 70% by weight of a polyepoxide based on a polyhydric phenol, a2) from 5 to 50% by weight of a polyoxyalkylene-polyol, a polyoxyalkylenepolyepoxide or a mixture of these compounds, a3) from 10 to 50% by weight of a polyhydric phenol, a4) from 0.5 to 30% by weight of a phenolic compound which reacts monofunctionally toward epoxides, B) from 5 to 40% by weight of a sulfide and C) from 0 to 10% by weight of additives.

3. A pigment formulation as claimed in claim 1, in which component (A) is an epoxide-carrying resin based on a) polyepoxides based on bisphenol A, a2) at least one polyoxyalkylenepolyepoxide selected from the group consisting of the polyoxyethylene polyepoxides, polyoxypropylenepolyepoxides and polyoxybutylenepolyepoxides, a3) bisphenol A and - 19 - O.Z. 0062/02110 a4) at least one phenolic compound which reacts monofunctionally toward epoxides and is of the formula I

(I) where R is H, CH3 or CH2CH3 and independently thereof n is from 1 to 20.

4. A pigment formulation as claimed in claim 1, in which the phenolic compound (a4) is nonylphenol, dodecylphenol or a mixture of these compounds.

5. A pigment formulation as claimed in claim 1, in which the sulfide is a di-(hydroxy-C2-C12-alkyl) sulfide.

6. A process for the preparation of a pigment formulation as claimed in claim 1, wherein .alpha.) from 10 to 90% by weight of an aqeuous dispersion containing from 1 to 30% by weight of synthetic resins (I), .beta.) from 10 to 80% by weight of a pigment powder (II) and .gamma.) from a to 10% by weight of assistants, the components (.alpha.) to (.gamma.) summing to 100% by weight, are used.

7. A process for electrocoating articles, wherein a pigment formulation as claimed in claim 1 is used.