CA1093740A - Coating materials and compositions - Google Patents

Abstract

A B S T R A C T

Process for the preparation Or resinous compounds, suitable for making water-dilutable coating compositions, which resinous compounds have an acid value of at least 35 mg KOH/g and having at least 200 milli-equivalents aliphatic hydroxyl per 100 g, by reacting at temperatures from 100 to 150°C a cyclic dicarboxylic acid anhydride with an epoxy resin ester having at least 260 milli-equivalents aliphatic hydroxyl per 100 g.

Description

-2- ~3~

The invention relates to coating materials and com-positions, their preparation, and their use on metal substrates.
~poxy resins are well-known binder materials in the coating industry; they can be applied in combination with hardeners (cross-linking agents) of various types, such as amines~ carboxylic compounds,or amino- or phenol-formal-dehyde resins, or t~ley can be converted first to soluble, ~usible derivatives such as esters, for specific applications, such as in primers on steel. For application in aqueous systems it is preferred to use a resinous material having a certain amount of carboxyl groups which are at least partly neutralized with an alkaline compound, such as an alkali metal hydroxide, ammonia~ or an amine,to make it water-dilutable; examples of such epoxy resin-based binders and their use can be found in British patent specifications 962,974 and 972,169, according to which epoxy resins are esterified with fatty acids and the esters reacted with certain dicarboxylic acids or anhydrides thereof to introduce a sufficient number o~ free carboxyl groups in the ester molecule For good salt-spray resistance (a requirement for automotive primers) the steel has to be phosphatized, ; before application of these or similar epoxy resin-based primers.
It has now been found that good salt-spray resistance can also be obtained on non-phosphatized steel, with epoxy resin-based primers.

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The invention provides a process for the preparation of resinous compounds, suitable for making water-dilutable coating compositions a~ter neutralization, wherein (a) a component (I) having the formula:

Q t CH2-CH-CH2-M ~ CH2-CH-CH2-Q
dH n~ OH

wherein n1 is a number which is on average from 3 to 7, Q stands ~or R"~C-O- , with R" being a hydroxyalkyl group when n is on average from 3 to 5, and R" being an alkyl or hydroxyalkyl group when nl is on average greater t~a~ 5, M is a ~O-Ph-C ~ ---Ph-O group when nl is on average from 3 to 5, and wherein for values of n greater than 5, M has the same meaning with the proviso that at leas.t one M in the above formula is represented by a -O-C-(CH2)m-C-O- group, wherein m is a number ~rom 2 to 10, 0 ~0 and Q is the same as Q, or hydroxyl, component (I) having at least 260, and pre~erably at least 320 milli-equivalents aliphatic hydroxyl per 100 g, is reacted with (b) a component (II) reacting as a cyclic carboxylic acid anhydride with a hydroxy compound in the temperature range of from 100 to - 4- ~

150C, in an amount sufficient to obtain a product (III) having an acid value of at least 35 mg KOH/g and having at least 200, and preferably at least 250 milli-equivalents aliphatic hydroxyl per 100 g.
The carboxyl-contai.ning reaction product (LII) can then, if desired, be reacted with a monoepoxide, in such an amount that the aci~ value is reduced to a value corre-sponding with about 2 carbo~yl groups per molecule; or prodllct (III) can be used as such~ if desired after partial or complete neutralization, in coating compositions~
One group of starting materia~ for the preparation of component (I) is formed by polyglycidyl ethers of 2,2-bis(4-hydroxyphenyl)propane. Such glycidyl ethers may be represented by the general formula:

. /o\ I OH l ~\
CH2-cH-cH2 _ - O-R-O C~2~CH-CH2- -o-R-o-c~2-cH-cH2 .~ _ n in which R represents the dival.ent group:

_ ~ ~ C9 ~

and n has an average value of from O to~ preferably, 5.
Theoretically polyglycidyI ethers ~rom a dihydric phenol have two epoxy groups per molecule but during the preparation some of the kerminal glycidyl groups may be hydrated to CH2-CH-CH2- groups by reaction with water.
OH OH

-5~ 7~

Polyglycidyl means that the ether has on average more than one epoxy group per nolecule.
The component (I) can be prepared in various ways, by reacting a polyglycidyl ether of 2,2 bis(4-hydroxyphenyl)-propane with other compounds capable to build up the re--quired molecular structure~ which is essential linear, while avoiding cross~linking reactions which would raise the viscosity too much, and could give rise to gelatinous materials.
One type of preferred component (I) can be prepared by reacting (A) one epoxy equivalent of a polyglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane having a molecular weight in the range of from 700 to 2000 and an epoxy equivalent weight in the range of from 400 to 1200, and in particular a molecular weight in the range of from 1000 to 2000 and an epoxy equivalent weight in the range of from 700 to 1200, with (B) from o.8 to 1.0 molar amounts of a hydroxy alkane monocarboxylic acid, at a temperature below 150C.
In the above formula of component (I)~ n has then a value of on average from 3 to 5;Q is then the same as Q1, and both are residues o~ hydroxy alkane monocarboxylic acids.
Examples of hydroxy alkane monocarboxylic acids are:
hydroxy acetic acid, lactic acid, hydroxy butyric acid, hydroxy valeric acid3 hydroxycaprylic acid, 12-hydroxy stearic acid, and dimethy~ol propionic acid.

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Another preferred component (I) can be prepared by reacting a~ a temperature below 150C (1) 4 epoxy equivalents of a polyglycidyl ether of 2,2-bis(4-hydroxy-phenyl)propane having an epoxy equivalent weight of from 400 to 500 with (2) from 1.8 to 2.2 acid equivalents of an aliphatic dicarboxylic acid, and (3) from 1.6 to 2.2 acid equivalents of a hydroxyalkane monocarboxylic acid.
Other preferred components (I) can be prepared by reacting at a temperature below 150C (1) from 5 to 7 epoxy equivalents of a polyglycidyl ether of 2,2-bis-(4-hydroxyphenyl)propane having an epoxy equivalent weight of from 170 to 250 with (2) from 3 to 5 carboxy equi-valents of an aliphatic dicarboxylic acid, (3) from 3 to 5 phenolic equival.en~s of a dihydric phenol, and (4) from lo9 to 2.1 epoxy equivalents of a glycidyl ester of a monocarboxylic acid.
; All these types of component (I) are prepared at temperatures below 150C, to avoid reaction of aliphatic hydroxy groups with epoxy groups or carboxy groups, and to promote reaction o~ epoxy groups with carboxy and with phenolic hydroxy groups. Preferably a catalyst is used, examples of which are quaternary ammonium salts, quaternary phosphonium salts, quaternary ammonium hydroxide~ tertiary amines or phosphines or salts thereof, al~ali metal hydroxides, lithium halides, and stannous salts of monocarboxylic acids, such catalysts may be used in amountsof preferably from 0.1 7 ~3t7,,~g3 to 5 per cent by weight, based upon the total weight of reactants. Volatile solvents may be used to keep the viscosity low.
In the ranges of reackants indicated, the mean of each range is preferred.
The pre-'erred dihydric phenol (2) is 2,2-bis-~-hydr~xyphenyl)propane, a commercial product also known under the name "Bisphenol A'l.
The dlcarboxylic acids can be identified with the formula:
H2C`- ~ CH2 ) nïC2~1' wherein m is from 2 to 10.
They are well-known saturated aliphatic dicarboxylic acids. Preferred is adipic acid.
Glycidyl esters to be used in the above reaction scheme for preparation of component (I) are preferably glycidyl esters of saturated aliphatic monocarboxylic acids in which the carboxyl group is attached to a tertiary or quaternary carbon atom, and which carboxylic acids have preferably 9 to 11 carbon atoms per molecule; such acids will later be named 'lalpha-branchedl acids.
The reaction or reactions to obtain the intermediate component (I~ may be per~ormed by mixing the components and heating the mixture to the required reaction temper-ature3 or by heating one component to be used in excess to the reaction temperature and adding the other component -8- ~ t~

or components gradually, in one or more stages.
The last two processes for making a component ~I) have the advantage that the incorporation of saturated aliphatic dicarboxylic acid provides an improved flexibility to the ultimate eoating, The last process has the additional advantage that all the base materials are readily available commercial products of reasonable price.
The eomponent (I) is then reacted in a separate step (b) with a compound (II) which reacts as a cyclic carboxylic acid anhydride with a hydroxy compound in the temperature range of ~'rom 100 to 150C in an amount sufficient to obtain a half-ester product having an acid value of at least 35. Acid value is the r.umber of mg KOH for titration o~ 1 gram of product. The reactiGn conditions in step (b) are so chosen that reaction of anhydride groups with hydroxyl groups predominates, the reaction temperature is preferably kept below 150C, for example at 100-140C.
Cyclic earboxyli.c acid anhydrides for the purpose of this invention are defined as compounds having one carboxylic acid anhydride ring:

\~/ \
\o /l \c/
~o per molecule; khey may contain further a carboxylic acid group. Examples are cyclic anhydrides o~ aliphatic, aromatic or allcyclic dicarboxylic acids, such as maleic, succinic, dodecenyl succinic, phthalic~ tetrahydrophthalic, hexahydrophthalic, endomethylene tetrahydrophthalic, and methyl endomethylene tetrahydrophthalic anhydride. Examples of compounds containing one carboxylic acid anhydride ring and further a carboxylic acid group are trimellitic an-hydride and adducts of maleic anhydridé and ethylenically unsaturated fatty acidsj with trimellitic anhydride preferred.
Further, certain combinations and reaction products of trimellitic anhydride with glycidyl esters of alpha-branched saturated aliphatic monocarboxylic acids can be used. These two compounds can be added separately to component (I) in reaction (b). A further possibility is to react first the trimellitic anhydride and the glycidyl esters in a molar ratio of from 0.~:1 to 1:1.2 (for example from 1:1 to 1:1.2) at a temperature below 100C; this type of reaction has been described in British patent specification 9349407. The product lS an acidic polyester, most probably formed by addition of epoxy groups to carboxyl groups, and half-ester formation of the hydroxyl groups with anhydride groups. Although the exact reaction scheme with such a precondensate in reaction (b) has not been investigated, such a precondensate reacts with the hydroxy-rich component (I) as a cyclic carboxylic acid an-hydride. Probab]y the half-es-ter groups in such a pre-condensate decompose above 100C to give anhydride groups and O~-groups (a phenomenon known for half-esters), and the anhydride groups react then preferentially with OH-groups of component (I), which are present in large excess.
An advantage in the use of trimellitic anhydride/
glycidyl ester precondensate as described above is the improved storage stability of the aqueous solutions of the neutralized final resinous compounds.
For the production o~ water-dilutable resinous materials having suitable properties as paint binders the products of step (b) can be neutralized partly or completely.
The acid value of the reaction product of step (b) can, if desired~be reduced by reaction with a monoepoxide in such an amount that the acid value of the product is still at least 35 (an acid value of at least 35 is a practical lower limit for water dilutability of the neutralized product) under conditions at which reaction of carboxyl with epoxy prevails~ that is at temperatures below 150C, and preferably in the presence of catalysts;
the conditions are essentially the same as described above for the preparation of component (I).
The amount of monoepoxide to be used for this modification is preferably such that the acid value of the final resinous product is reduced to a value corre-sponding with about 2 carboxyl groups per molecu]e.
Monoepoxides for use in this modification are exempliI`ied by monoepoxy alkanes, monoepoxy ethers, and mono-epoxy esters of monocarboxylic acids. Examples of mono-epoxy alkanes are ethylene oxide~ propylene oxide, butylene oxide, octylene oxide. Examples of monoepoxy ethers are butyl glycidyl ether, octyl glycidyl ether, phenyl glycidy~ ether5 and cresyl glycidyl ether. Preferred are glycidyl esters of '~alpha~branched' acids as defined above.
The hydroxy-containing resinous materials prepared according to the present invention have preferably an aliphatic hydroxyl content of from 200 to 500, more prefer-ably from 250 to 500, milliequivalent per 100 g.
The range of reactions and conditions to perform them properly has advantages over those used in earlier processes as indicated above: the temperature during the whole series of reactions is rather low, which improves selectivity, reduces side reactions, and improves the colour of the final product.

~3~7~

If desired the reactions may be carried out in the presence of suitable non-reactive solvents, such as hydrocarbons or ketones; volatile solvents are pre~erred.
For preparation of water-dilutable binders, e.g.
for electro-deposition purposes the products may be neutralized partly (e.g., for at least 50%), or com-pletelyj lyotropic ~lvents such as ethylene glycol monobutyl ether may be added as well. An adjustment to a certain pH by partial neutralization may be desirable in connection with proper dispersion of pigrnents.
Pigments, fillers, dispersing agents, and other components known in the art of paint formulation may be added, and also cross~linking resins such as phenol formaldehyde resins~ or a~lino formaldehyde resins. The amount of such cross-linking resins is preferably small~
e.g. 1 to 7 weight per cent of the neutralized product for improved adhesion on bare steel. For use on phosphatized steel a higher amount of cross-linking resin may be used, for example 20 to 30 parts by weight per 80 to 70 parts by weight of the neutralized product.
The water dilutable paints and lacquers can be applied by a variety of methods as known in the art, for example by electro-deposition, by spraying, dipping, roller coating, curtain coating. The coatings can be hardened by stoving.
The invention is illustrated by examples. Parts and percentagestherein are by weight~ unless otherwise indicated.

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"Bare" steel is degreased steel. "Cymel" 301 is hexa-methoxymethyl melamine ("Cymel" is a re~istered trade mark). The glycidyl ester of'alpha-branched"acids had an epoxy equivalent weight of 246. Aliphatic hydroxy content was on non-volatiles.
EXAMPLE I
A polyglycidyl ether of 2,2-bis(4-hydroxy phenyl)-propane having an epoxy equivalent weight of 893 (1786 g;
2 epoxy equivalents) was reacted in a reaction flask with stirrer~ thermometer, and heating mantle with dimethylol propionic acid t268 g; 2 mol.) in the presence of benzyl dimethyl amine as catalys~ (5 g) during 4 hours at 140C
until the acid value was below 4. The aliphatic hydroxyl content was 600 meq./100 g. Then succinic anhydride (400 ~; 4 mol.) was added, and the mixture was kept at 140C during one hour.
Then a commercial glycidyl ester of "alpha-branched"
acids (492 g; 2 mol.) was added~ and the mixture was further reacted at 140C during 12 hours. The acid value was then 38.1 and the aliphatic hydroxyl content 340 meq.
per 100 g.
After cooling to 80C ethylene glycol monobutyl ether was added (20 parts per 80 parts o~ reaction product), and the mixture was neutralized with 90 per cent. of the theoretical amount of triethyl amine. A melamine formaldehyde resin (XM 1116, or "Cymel" 301 of American Cyanamid Company) -l L~ 3 7~

was added (5 parts per 95 parts of reaction product); and the soluticn was diluted with demineralized water to a solids content of 10 per cent.
This solution was electro deposited on bare sceel panels at 150-200 V at 30C. The panels were stoved at 180C during 30 minutes. The coating thickness was 18-22 microns.
In the salt spray test (ASTM B 117) the underrust creep was less than 3 mm after 240 hours. The impact resistance (BS 1391), reverse, was the equivalent of 90 cm.kg.
Similar corrosion resistance was obtained when the solution was applied by spraying or dipping (coatings 20-25 microns thick).
EXAMPLE II
_~, A "liquid" polyglycidyl ether of 2,2-bis(4-hydroxy phenyl)propane having an epoxy equivalent weight of 186 (1118 g; 6 epoxy equivalents) was mixed and heated to 120C with a mixture of adipic acid (292 g; 2 moles), diphenylolpropane (456 g; 2 moles) and glycidyl esters of alpha-branched acids (492 g; 2 moles). Catalyst was added (benzyl dimethylamine; 4.5 g) and the mixture heated /luring 1 hour at 120C, 2 hours at 130C, and 1 hour at 140C.

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The clear yellow product had analytical values as follows:
acid content : < 0.01 meq. C02H/g epoxy content : 0.09 meq./g phenolic 0~l content : o.48 meq./g aliphatic OH content: 340 meq./100 g At 140C succinic anhydride (200 g; 2 moles) was added, and heating was continued during 2 hours at 135C. The aliphatic OH content was 230 rneq/100 g.
l'his mixture was then diluted wi~h ethylene glycol mono-butyl ether to a solids content of 80%, and further cooled ; to ambient temperature.
This binder solution was neutralized with 90% of the theoretical amount of triethylamine, blended with a com- -mercial mela~ine resin ("Cymel" 301 of American Cyanamid Company) at a 95:5 weight ratio and diluted with de-mineralized water to a solids content of 10%w. This solution was used for application of a primer by electro-deposition at 150 V onto bare steel panels. The coatings were 20 25 microns thick, after stoving at 180C during 30 minutes they had an excellent impact resistance (~ 30 cm.kg in the reverse ~S 1391 test) and a rust creep of 5 mm in the ASTM B117 salt spray test (after 240 hours).

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EXAMPLE III
Example II was repeated, with the exception that in the second stage the succinic anhydride was replaced by trime]litic anhydride (576 g; 3 molesj at a temperature of 140C, immediately followed by glycidyl esters of alpha-~,ranched acids (861 g; 3.5 epoxy equivalents).
The reaction mass exothermed to about 150C, and was kept then at 145C during 1.5 hours; the acid value of the product was 35, the aliphatic 0~l content 220 meq./100 g.
The resin was diluted with ethylene glycol monobutyl ether to give a solids content of 70%w, and neutralized and further t~eated as described in Example II.
Bare steel panels, electro-coated with this binder (10% solids; weight ratio of this binder/"Cymel": 95/5, 200 V ED; stoved at 180C during 30 minutes, coating 16-20 microns thick) had in the ASTM B117 salt spray test a rust creep of 5 mm.
E~A~IPLE I~l Example III was repeated with slight modifications.
A condensation product from "liquid" polyglycidyl ether, adipic acid, diphenylol propane, and glycidyl esters of alpha-branched acids as prepared in E~ample II (2360 g) was heated in a 10 l glass reactor to 140-145C. Powdered trimellitic anhydride (4~0 gg 2.5 moles~ was added, and the mlxture was kept with stirring at 140-145C during 15 minutes. Glycidyl ester of alpha-branched acids (640 g, 7 ~3t7~

2.6 moles) was added, and th(~rllix~ure was kept with stirring at 140C during 1.5 hours. The product, a clear, yellow resin (acid value 36 mg KOH/g, aliphatic hydroxyl 230 meq./100 g) was diluted with ethylene glycol monobutyl ether (1492 g), the solution (70~w solids) was cooled to ambient temperature and neutralized with 80/o of the theoretical amount of triethyl amine. This solution was blended with hexamethoxymethyl melamine in a 95:5 solids weight ratio, and thinned with water to lO~w solids. The clear solution hada pH = 7.2.
The storage stability Or this solution was examined by keeping the solution at 40C in a closed container, and taking at regular intervals a sample for electro-deposition (150 V/25C, bare steel anodes). The results are shown in the following Table:

Storage time Film thickness Film weeks at 40C (micron) appearance .... ..
0 18-20 smoothg glossy 1 18-20 smoot~, glossy 2 20-22 smooth

3 20-22 rough, no gloss

4 25-30 film ruptured The Table shows that satis~actory films were obtained for storage ~imes of up to 2 weeks only.
EXAMPLE V
This example demonstrates the improved storage time when using a prereaction product Or trimellitic anhydride and "Cardura" E 10.
A. Prereaction product, preparation __ A mixture o~ trimellitic anhydride (4~0 g, 205 moles), glycidyl ester of alpha-branched acids (640 g, 2.6 moles), methyl ethyl ketone (747 g) and benzyl dimethyl amine (2.3 g) was heated in a 3-litre glass reactor equipped with thermometer, stirrer, and reflux condenser. A slightly exothermic reaction started at about 70C, and brought the temperature to a maximum of 93C with re~lux. The solution was kept at 90-95C during 6 hours, and then cooled. The solution had the following properties:
colour :slightly hazy yellow solids :60%w epoxy :0.03 meq./g (on solids) acid value:127 mg KOH/g (on solids) viscosity (Gardner-Holt): M (25C; solution) B. A condensation product as descrlbed in Example II
(2360 g) was heated in a 10 1 glass reactor equipped with stirrer, thermometer, dropping funnel and distillation head to 145C. Through the dropping funnel a pre-reaction -19~ 7~ ~

product of part A of this Example (1870 g) was added in 30 minutes while the methyl ethyl ketone was distilled off and the batch temperature was kept at 130-135C. Then the batch temperature was raised to 145C, and kept there for 1- hour. The resulting clear yellowish resin has an acid value of 35 mg KQH~g and an aliphatic hydroxyl content of 230 meq./100 g; it was diluted with ethylene glycol mono-butyl ether to 70%w solids and the clear solution was cooled to room temperature.
A 10%w aqueous solution was prepared as described in Example IV and evaluated for storage stability (by the same procedure)~ the results of which ~e shown in the following Table:
15Storage time Film thickness Film weeks at 40C (microns) appearance 0 17-1~ smooth, glossy ; 2 18-20 smooth~
glossy 4 20-22 smooth, glossy It is apparent that the storage stability of the neutralized aqueous solution of this binder is con-siderably better than that of Example IV.
Films from neutralized products of this example, applied by electrodeposition on bare steel panels and baked (3 minutes/180C; thickness about 20 microns) had excellent propertles? as shown in the fol3owing table:

.

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Reverse Impact (British Standard): ~ 90 inch.lb (101 cm.kg) Rust creep (ASTM salt spray 240 hours) < 5 mm Conical mandrel bend : passed 1/8 inch (passed 0.3 cm) Hardness (pencil) : F-H
Eiardness (Konig) : 180 seconds Adhesion (Gitterschnitt) : excellent Solvent resistance : xylene 15 minutes slight softening EXAMPLE VI
A 10-litre reactor equipped with anchor stirrer~ reflux condenser, thermometer, and dropping funnel is provided with a polyglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane having an epoxy equivalent weight of 483 (4 epoxy equivalents, 1(332 g) and toluene (235 g)g and heated to 140-145C.
Adipic acid ~146 g, 1~0 mole), dimethylol propionic acid (268 g, 2.0 moles) and benzyl dimethyl ~mine (5.8 g) ; are added~ and the mixture is stirred at 140-145C until the acid value is below 2 mg KOH/g (on solids); this takes about 4 hours. The aliphatic hydroxyl content is then 340 meq./100 gO
The reflux condenser is then rearranged for distillation, and a resin solution prepared according to Example V A(1870 g) is gradually added through the dropplng funnel while distilling off the volatile matker (mainly methyl ethyl ketone) with stirring, at a batch temperature of about -21~

135C; this takes about 2 hollr. The batch is then further heate~ with stirring (batch ternperature about 135-140C) ~ntil the acid value is 36 mg KOH/g (about 1 hour)~
with preferably a slight stream of inert gas (e.g., nitrogen) passing through to promote removal of solvent. The aliphatic hydr-oxyl content of` the resin was 230 meq./100 g.
EXAMPLE `VI_ Paint and evaluation of product obtained by Example VI.
This product (140 g, 137 g non-volatiles), diethylene glycol moncbutyl ether (35 g) and isophorone (17.5 g) are charged to a 1 litre flask equipped with anchor stirrer, dropping funnel~ re~lux condenser~ and thermometer;
the mixture is heated to about 80C until homogeneous, and then cooled to about 35C; then an oil-soluble phenolic resin ("Setalite" lOO*in 71.2%w solution in monobutyl ether of diethylene glycol~isophorone 2:1 wto ratio) is added and then triethylamine (7.4 g).
When the mixture is homogeneous, demineralized water (424 g) is added slowly and gradually at a temperature of about 30C with stirring. The resulting solukion had a bluish-milky appearance; the solids content was 24.5%w and the degree of neutralization Oo830 200 g of this solution were ballfmilled for 48 hours with titanium dioxide (36 g)~ carbon black (2 g) and clay (2 g). A ~urther 390 g of the aqueous binder solution was added, and the mixture further ballmilled during 30 minutes.

* trademark . . . :

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This mixture was diluted with ~20 g of demineralized water, to a paint with solids content 14.8~w and pl~ 7.1. This paint was electrodeposited on bare steel panels at 150-200 V at 30C. The panels were stoved at 180C
durirlg 30 minutes, The properties of the stoved coating were:
thickness 18-22 microns salt spray (ASTM B 117) underrust creep after 240 hours: 3 mm hardness (Konig) 180 seconds impact (reverse) 90 cm.kg mandrel behd (conical) passed 3 mm

Claims (16)

C L A I M S

1. A process for the preparation of resinous compounds suitable for making water-dilutable coating compositions after neutralization, wherein (a) a component (I) having the formula:
wherein n1 is a number which is on average from 3 to 7, Q stands for a group with R" being a hydroxyalkyl group when n1 is on average from 3 to 5, and R" being an alkyl or hydroxyalkyl group when n1 is on average greater than 5, when n1 is on average from 3 to 5, and wherein for values of n1 greater than 5, M has the same meaning with the proviso that at least one M in the above formula is represented by a group, wherein m is a number from 2 to 10, and Q1 is the same as Q or hydroxyl, component (I) having at least 260 milli-equivalents aliphatic hydroxyl per 100 g, is reacted (b) with a component (II) reacting as a cyclic carboxylic acid anhydride with a hydroxy compound in the temperature range of from 100 to 150°C, in an amount sufficient to obtain a product (III) having an acid value of at least 35 mg KOH/g and having at least 200 milli-equivalents aliphatic hydroxyl per 100 g.

2. A process as claimed in claim 1, wherein component (I) has at least 320 milli-equivalents aliphatic hydroxyl per 100 g.

3. A process as claimed in claim 1, wherein product (III) has at least 250 milli-equivalents aliphatic hydroxyl per 100 g.

4. A process as claimed in claim 1, wherein product (III) is reacted with a monoepoxide in such amount that the acid value is reduced to a value corresponding with about 2 carboxyl groups per molecule.

5. A process as claimed in claim 1, wherein component (I) is a reaction product of (A) one epoxy equivalent of a poly-glycidyl ether of 2,2-bis(4-hydroxyphenyl)propane of the general formula wherein R represents the divalent group with (B) from 0.8 to 1.0 molar amounts of a compound having at least one aliphatic hydroxyl group and one carboxyl group per molecule, at reaction temperature below 150°C.

6. A process as claimed in claim 5, wherein component (I) is a reaction product of (A) one epoxy equivalent of a polyglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane having a molecular weight of from 700 to 2000 and an epoxy equivalent weight of from 400 to 1200 with (B) from 0.8 to 1.0 molar amounts of a hydroxyalkane monocarboxylic acid, at reaction temperature below 150°C.

7. A process as claimed in claim 1, wherein component (I) is a reaction product of (1) 4 epoxy equivalents of a polyglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane having an epoxy equivalent weight of from 400 to 500 with (2) from 1.8 to 2.2 acid equivalents of an aliphatic dicarboxylic acid, and (3) from 1.6 to 2.2 acid equivalents of a hydroxyalkane mono-carboxylic acid, the reaction having been performed below 150°C.

8. A process as claimed in claim 1, wherein component (I) is a reaction product of (1) from 5 to 7 epoxy equivalents of a polyglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane having an epoxy equivalent weight of from 170 to 250 with (2) from 3 to 5 carboxy equivalents of an aliphatic dicarboxylic acid, (3) from 3 to 5 phenolic equivalents of a dihydric phenol, and (4) from 1.9 to 2.1 epoxy equivalents of a glycidyl ester of a mono-carboxylic acid, the reaction having been performed below 150°C.

9. A process as claimed in claim 1, wherein component (II) is a cyclic dicarboxylic acid anhydride.

10. A process as claimed in claim 1, wherein component (II) is trimellitic anhydride.

11. A process as claimed in any of claims 1 or 10, wherein component (II) is a product prepared by reacting trimellitic anhydride with a glycidyl ester of saturated aliphatic monocar-boxylic acids in which the carboxyl group is attached to a tertiary or quaternary carbon atom and which carboxylic acids have 9 to 11 carbon atoms per molecule in a molar ratio of from 0.8:1 to 1:1.2 at temperatures below 100°C.

12. A process according to claim 1 including a further neutralization step wherein at least 50% of the carboxyl groups of a product (III) are neutralized.

13. A process for the preparation of a thermosetting coating composition, wherein an aqueous solution of 100 parts by weight of a neutralized product prepared according to claim 12 is combined with from 1 to 7 weight per cent of a cross-linking resin.

14. Resinous compounds prepared according to claim 1.

15. Water-dilutable binder prepared according to claim 12.

16. Thermosetting coating composition, prepared according to claim 13.