CA2132106C - Graft copolymers, process for preparing the same, aqueous coating masses and their use for coating packages - Google Patents

Abstract

The invention relates to graft copolymers a) which are obtainable from A) epoxy resins having an epoxide equivalent weight of at least 500, preferably at least 700, and/or phenoxy resins, B) carboxylic anhydrides containing at least one polymerizable, ethylenically unsaturated double bond per molecule, and from C) further ethylenically unsaturated monomers, at least some of which may, if desired, contain a carboxyl group, where the ratio between the weight of A) and the total weight of monomer components B) and C) is in the range from 90:10 to 10:90. The invention also relates to coating compositions based on the graft copolymers a), and to their use for coating packaging containers.

Description

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2 1 ~ ~ 1 () f) 70.01.1993/f~
PAT 92 322 i~
FILE ~tdlN ~,-J~ !!iL D
T~T TRANSL~iI iJil FEC659 , ~, - . ~, .~ .
5 BASF Lacke + Farben AG, Mun~ter Graft copolymer~, ~LC28~ for their preparat~on, ~ ~' a~. 90_~ coat~ng compo~ttion~, and their u~e for coat~ng ~ ( ;
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The present invention relates to graft copoly-mers made from epoxy or phen~Yy resins, ethylen;~Ally unsaturated monomers contAining acid anhydride yLUUp8 and further ethylen;cAIly unsaturated monomers. The invention furthermore relates to a process for the preparation of the graft copolymers, to aqueous coating compositions which contain the graft copolymers, to a process for the preparation of the aqueous coating compositions, and to their use for coating packaging containers.
High-moleclllAr-weight epoxy resins and ph~nQYy resins are suitable for the preparation of coating materials for sheet metal pAckAging containers, in particular coating materials for the internal protec-tion of sheet metal pa~kAging containers. Examples ofthe crossl;nking agents used are phPnolic resins, -1 r ; ne resins and urea resins. Solvent-based coating cr -sitions of thi~ type contain, due to the specified application viscosity, a solvent content of between 60 and 70% by weight. If, as i~ the case in the surface coating of two-part beverage cans, the coating i8 applied pre~ ;n~ntly by spraying, a further increase in the solvent content usually results, which has the consequence of Gonqiderable pollution due to solvent emissions.
~ he advantages of aqueous coating systems by cc ~rison are a significantly re~nce~ solvent emission. In coating material~ for the internal protec-tion of cans, it must also be taken into consideration that these coating materials must meet strict foodstu~f '-regulations. Coatings on the inside of cans must be i stable on storage in contact with foodstuffs as the contents. Coating materials for the internal protection of cans in the foodstuffs and beverages sector must therefore ensure adequate contents resistance, adequate pasteurization stability and sterilization stability.
Solvent-cont~;n;ng coating materials for the internal protection of cans which have good properties J~,,>~I
and are based on combinations of epoxy re~ins and phenol-formaldehyde resin~ or ~m; no resins have been known for some time. In particular, epoxy resins ba~ed on bisphenol A having a mean molecular weight of greater than 3,000 give very resistant coating~
For use of such systems in aqueous -'; , the epoxy resin must be modified by the introduction of solubilizing y~OUp8 in such a way that a water-~oluble or water-dispersible system is formed. Since resins cont~;n;ng amino groups give stability we~knesses on 2 1 ~ 2 1 0 6 contact with the contents, which are predominantly acidic, high-molecular-weight and thus predominantly hydrophobic epoxy resins are rendered water-soluble or water-dispersible by modification by means of carboxyl groups. Thus, for ~Yr le, EP-A-6334 and EP-A-6336 disclose aqueous coating materials for the internal protection of cans which are based on products of a reaction of epoxy resins with acrylate copolymers containing COOH groups. The epoxy esters formed are converted into a water-dispersible form by neutraliza-tion of the CArhOYyl yLOUp~ present in the acrylate chain. The b-hydLG~y esters disclosed in the publi-cations can be cured with the aid cro881 i nki n~ agents.
WO 89/1498 relates to aqueous dispersions which are suitable as coating compositions for metal containers for storing foodstuffs and beverages. The coating c~ -~itions contain b;n~r mixtures prepared by addition polymerization of relatively ;n~Yren~ive monomers, such as, for example, styrene, in a reaction medium cont~;n;ng modified epoxy resins. These are obtA;ne~ by reaction of some of the epoY;~ groups with ethyle~; CA 11y unsaturated monomers containing groups which are reactive with epoY;Ae groups, such as, for example, unsaturated carboxylic acids, and reaction of further epox;~e groups with tertiary amines and with a preaddition polymer which contains carboxyl groups and contributes to the water-dispersibility.
However, the water-dispersibility of the modified epoxy resins disclosed in said publications is i771t~7qlo~
ii' _ 4 -in need of improvement. This may be attributable to the fact that the modification nece6sary to provide water-dispersibility takes place only at the epoxide groups.
US Patent 4,212,781 and US Patent 4,308,185 disclose aqueous coating c. ~~sition~ for pAck~g;ng containers, whose b;n~ers are prepared by free-rA~;c~
graft polymerization of ethylenically unsaturated monomers, some of which contain carboxyl groups, in the presence of an epoxy re~in, using at least 3% by v~
weight, based on the total weight of the monomers, of perox;~;c initiators. Use of the relatively large amounts of initiator cleaves C-H bonds in the epoxy resin chain, and acrylate side chA;n~ are grafted onto the epoxy re~in main chain at these points, carbon-lS carbon l;n~eo being formed. A disadvantage here isthe unavoitable relatively high initiator concentration.
DE-C-27 47 818 discloses water-~;~persible epoxy resins which are prepared by a process in which an epoxy resin cont~;n;ng on average more than one epoY;~e group per molecule is, if desired, chain-exten~e~ by means of a ~;~h~nol and subsequently reacted with a saturated carboxylic anhydride to the desired acid number of from 5 to 200 mg of RO~/g. The chain exte~io~ is carried out by reacting all the epoY; ~e groups. However, the water-dispersibility of the b;n~rs disclosed in this publication is in need of improvement.

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Finally, DE-A 2~ 08 880, 26 08 828, 26 08 839, .
26 08 869, 26 08 901, 26 08 931, 26 08 941 and 26 08 942 disclose graft copolymers prepared by react~
ing liquid epoxide c. _ n~c having epoY;~e equivalent 5 weights of from 120 to 450 with ethylen;cAlly unsatura-ted carboxylic acids and/or unsaturated acid anhydrides having 3 to S carbon atoms, esters of acrylic acid, and acrylonitrile and/or methacrylonitrile. In the working examples, only unsaturated carboxylic acids are used, but no unsaturated carboxylic anhydrides, which are reacted with the epoxide groups of the epoxy resin. The graft copolymers are used in solvent-free and low-solvent coating and molding z~ itions. No aqueous coating compositions are described.
lS The object of the present invention wa~ to provide water-dispersible epoxy resin bin~rs which are ea~y and simple to prepare and have excellent water-di~persibility. The water-dispersible epoxy resins sho~ be suitable for use in aqueou~ coating materials for pA~A~ing containers, in particular in agueou~
coating material~ for the internal protection of cans.
The aqueous coating compositions prepared on the basis of the water-dispersible b; n~r~ shoul~ be suitable for .~
coating cans made from aluminum, t;nplAte and steel which has been specially surface-pretreated in another way. In addition, they ~o~ be suitable for coating preserved-food cans, which must be resistant to a broad range of contents, even under sterilization and pasteurization condition~. The aqueous dispersions ~ .. !. c'~

should have a long shelf life, and they ~ho~ be suit- ~
able for application without flaws, in particular by -;
spray coating. The coating films resulting from the aqueous coating - -~ition~ ~houl~ achieve at lea~t the property level of conventional coating materials for the internal protection of can~ with respect to freedom from pores, contents resistance, adhesion to metal sheeting, hardness, elasticity and flavor neutrality, or even surpass this level. In order to ~. ~
~; 10 a~sess the contents resistance, the pasteurization or sterilization stability of baked coating film~ with respect to various test solutions should be used.
The object of the present invention is achieved by graft copolymer~ of the type mentione~ at the outset, which are characterized in that the graft copolymers (a) are obtainable from ~-A) epoxy re~ins having an epoY;~e equivalent weight ~ ;
of at least 500, preferably at least 700, and/or phenoYy resins, ;~
B) carboxylic anhydrides cont~;n;ng at least one polymerizable, ethylen;c~lly unsaturated double bond per molecule, and from . :- . .. . .
C) further ethylen;cAlly unsaturated -n~ -rs, at least some of which may, if desired, contain a ~ -carboxyl group, where the ratio be~een the weight of A) and the total weight of -r~ -r _ ~rents B) and C) i~ in the range ;~ ~-f-om 90:10 to 10:90. ~ ~

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_ 7 -If component C) i8 not a monomer contA;n;ng cArhoYyl groups, the graft copolymers (a) obtained are not water-dispersible and can thus only be used in nonaqueous coating compositions. For use in water-5 thi nnAhle coating materials, in particular can-coating materials, adequate water-dispersibility of the graft copolymers (a) is necessary. The present invention therefore relates, in particular, to graft copolymers (a) which are obtainable from A) from 30 to 80% by weight, preferably from 50 to 75% by weight, of epoxy resins having an epoxide eguivalent weight of at least 700, preferably at least 1500, and/or ~h~n~Yy resins, and from 70 to 20% by weight, preferably from 50 to 25% by weight, of the sum of B) carboxylic anhydrides cont~;n;ng at least one polymerizable, ethylsnicAlly unsaturated double bond per molecule, and C) further ethyleni~Ally unsaturated monomers, at least some of which contain a carboxyl group, where the sum of the proportions by weight of components A), B) and C) is in each case 100~ by weight, from 0.02 to 0.5 mol of component ~) are used per mole of c - ~~t A), and the acid number of the graft copolymer (a) i9 in the range from 40 to 250 mg of KOH/g.
Component A) can be epoxy resins and/or p~noYy resins. Examples of suitable epoxy resins are those ~'J,i~"j"~""

2 1 ~J ,~
.: - 8 -ba~ed on bisphenols, preferably bisphenol A, it being necessary for these to have an epoY;~e equivalent weight of at least 500 or of at least 700. The suitable epoxy resins contain secondary hydroxyl ~LOUp8 in addition to the epoxide groups. According to the present invention, these secondary hydroxyl groups are reacted with the carboxylic anhydride component ~). It is therefore preferred to employ according to the present invention epoxy resins having a relatively high epQY;de equivalent weight, since the epoxy resin component should contain as many hydroxyl groups as pos~ible. Preference is therefore given to epoxy resins having an epoY;de equivalent weight of at least 700, and particular preference i3 gi~en to those having an epox~e equivalent weight of at lea~t 1,500. Suitable epoxy resins are aromatic polyglycidyl ethers, which are marketed, for example, under the tradenames Epikote 1001, Epikote 1004, Epikote 1007, Epikote 1008, Epikote 1055 and Epikote 1009.
According to the present invention, component A) may also be phe~Yy resins, if desired mixet with the epoxy resins described above. Suitable phenQYy resins can be prepared from ~;phenols~ such as bisphenol A, and epichlorohydrin, the phe~oYy resins having a higher mean molecular weight. They are hydroxyl yLOU~ contA;n;ng polyethers without terminal glycidyl y-OUp8-Examples of suitable carboxylic anhydrides contA;n;ng at least one polymerizable, ethyle~;cAlly ' f : ~ 2 ' ~i ' - ~13~1n~
9 , ~
unsaturated double bond (component ~) are acrylic anhydride, methacrylic anhydride, ~o~cenylsuccinic anhydride, tetrahydrophthalic anhydride and maleic anhydride. For the ~ppl;cAtion of internal coating~ of beverage and preserved-food cans, preference i8 given to acrylic anhydride and methacrylic anhydride. The amount of unsaturated carboxylic anhydride employed is varied ~epen~;n~ on the degree of grafting desired.
Examples of suitable ethylen;~lly unsaturated ,~.,.,;, monomers of c' -ne~t C) are styrene, a-methylstyrene, vinyltoluene, esters of acrylic and methacrylic acid, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, i8ep~0~yl acrylate, iisoyLopyl meth-acrylate, butyl acrylate, butyl methacrylate, amylacrylate, amyl methacrylate, i~obutyl acrylate, isobutyl methacrylate, hexyl acrylate, hexyl methacrylate, t-butyl acrylate, t-butyl methacrylate, decyl acrylate, decyl methacrylate, lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobo---yl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, octyl acrylate, octyl methacrylate, nonyl acrylate, nonyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 4-hy~LoAyLu~yl acrylate, 4-hydLoxy~tyl methacrylate, 5-hyd~oxyamyl acrylate, 5-hydroxyamyl methacrylate, 6-hyd oxyhexyl acrylate, 6-hydroxyhexyl methacrylate, 8-hydro~yocLyl acrylate, 8-hydroxyoctyl methacrylate, 2-hy-droxypropyl acrylate, 2 ~
,, .

2-hydroxypropyl methacrylate, 2-hydro~ybu~yl acrylate, 2-1lydLo~yL~tyl methacrylate, 3-hyd~oxyLu~yl acrylate and 3-hydro~ybu~yl methacrylate.
C~ --nt C) may also be ethylenlc~lly unsaturated monomers cont~;ning a carboxyl group. The use of these ethylsnicAlly unsaturated carboxylic acids i9 necessary if the graft copolymers (a) are required to have adequate water-dispersibility. Examples of suitable monomers cont~;ning a carboxyl group are acrylic acid, methacrylic acid and crotonic acid.
Monomer components B) and C) are preferably methacrylic anhydride and/or acrylic anhydride, and ethyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate and styrene respectively, and the acid monomers are preferably acrylic acid and/or methacrylic :. ,.::.,, i acid. Particular preference is given, in the area of ; ~-internal coating of beverage and prese~ved food cans~
to c~ ~inAtions of ethyl acrylate, styrene and ~- -methacrylic acid, or ethyl acrylate, methyl methacrylate, styrene and methacrylic acid, or . ~ . .: ~ .
alternatively 2-ethylhexyl acrylate, methyl -methacrylate and acrylic acid as ~ t C.
The graft copolymers (a) preferably have an ~ .
acid number of from 60 to 150 mg of XO~/g.
The graft copolymers according to the invention can be prepared by various methods. In general, com-ponent A) i8 reacted with the carboxylic anhydride -CC~,-nPnt B) in an organic solvent at temperatures of from 60~C to 160~C, preferably at from 100~C to 120~C, ~ -~
' '~

~1 ~t~1 ~ 6 .,., - 1 1 -a reaction taking place between the secondary OH group3 of the epoxy or phenoxy resin and the anhydride group of B). This reaction can be carried out, even when high-molecular-weight epoxy or phen~yy resins are used, at a high solids content, i.e. at ~olids contents of from 80 to 95%. Suitable solvents are those which are inert toward anhydride yLGu~s- Suitable solvents are ketones, ethers, possibly esters and hydrocarbons.
Examples are methyl n-propyl ketone, methyl isobutyl ketone, diisobutyl ether, n-propyl acetate, n-butyl acetate, isobutyl acetate, n-propyl propionate, ethyl butyrate and xylene.
In the reaction with the carboxylic anhydride, it should be ensured that anhydrou~ condition~ exist.
If desired, a cataly~t is used in the reaction of A) and B). However, the use of a catalyst is generally unnecessary.
After the reaction of A) and B), the ethy-leni~Ally unsaturated monomers of c~ _rent C) are polymerized, in a ~econd step in the presence of the product of the reaction of A) and B), in an organic solvent at temperatures of from 60~C to 200~C, preferably at from 120~C to 140~C, using at least 0.5%
by weight, based on the total weight of components B) and C), of initiators which form free r~;c~l~. At least 2.0% by weight, based on the total weight of B) and C), of initiators are preferably used.
Examples of suitable initiator~ are dibenzoyl peroxide, t-butylbenzoyl peroxide, tert-butyl 2 1 .3 ~

peroctanoate, cumene hydroperoxide and methyl ethyl ketone peroxide, t-butyl perbenzoate, di-tert-butyl peroxide, tert-butyl peroxy-2-ethy~h~xAnoAte, tert-butyl peroxyiso~on~no~te, tert-butyl peroxyisobutyrate, tert-amyl peroxy-2-ethylheY~noAte, peroxyketals, such ao 2,2-di-(tert-amylperoxy)propane and ethyl 3,3-di-(tert-amylperoxy)butyrate, azo compounds, such as azobiscyclohPYAnPn;trile and azobisisovaleriate- The initiator, dis~olved in some of the solvent employed for the polymerization, is grA~uAlly metered in during the polymerization reaction. The initiator feed preferably takes from about 1 to 2 hours longer than the monomer feed, in order in this way also to achieve a good action during the post-polymerization phase. If initiators having only a low decomposition rate under the prevA;l;ng reaction conditions are employed, it is also possible to initially introduce all or some of the initiator.
The reaction is preferably carried out in the presence of polymerization regulators in order to be able better to control the molecular weights or the molecular weight distribution. Suitable regulators are preferably mercapto compounds, particular preference being given to mercaptoethanol. Examples of other possible regulators are alkyl mercaptans, such a3, for example t-dodecyl mercaptan, octyl mercaptan, phenyl mercaptan, octyldecyl mercaptan and butyl mercaptan, and thiocarboxylic acids, such as, for eY~ le, thioacetic acid or thiolactic acid. In the case of 2 1 3 2 1 3 ~
~; - 13 -anhydride-functional comonomers, it must be en~ured that the regulator cannot react with the cyclic anhydride groups, or can only do 80 to a small extent.
In this case, preference is given to t-dodecyl 5 mercaptan.
These regulators are employed in an amount of up to 2% by weight, based on the amount of ~ r to be processed. They are preferably dissolved in one of the monomer feed~ and added with the monomers. For 010 initiation of the polymerization, at least 2.0% by weight, ba~ed on B) + C) of initiators are preferably employed.
Suitable organic solvent~ for the free-r~;cAl graft copolymeriz~t;on are - oAlcoholq having 3 to 18 15 carbon atoms, such as, for example, butanol, isobutanol, propA~ol~ i~opropanol, pentanol and isopentanol; and glycolethers, ~uch as, for example, butyl glycol, butyl diglycol, hexyl glycol and p~vpy lene glycol.
In the copolymerization carried out in the second step, any desired solvent can be used or added.
In order to p~ven~ the b;~er gell;ng during the preparation proces~ described at a high degree of grafting, i.e. at high amounts of -c ~ ), either the dilution with a suitable solvent must be selQcted appropriately during the free-rA~icAl copolymerization, either the product of the reaction of A) and B) being initially intro~uce~ in an organic solvent and the monomers and the initiator being metered in, or the 2 1 3 ~ S
1~' product of the reaction of A) and B) being metered in -~
with the monomers C) and the pero~i~;C initiator.
Furthermore, the graft copolymers according to :::
the application can be prepared by first polymerizing monomer component~ B) and C) in an organic solvent at temperatures of from 60~ to 200~C, preferably at from ,- .
120~C to 140~C, using at least 0.5$ by weight, based on the total weight of B) and C), of initiators which form ; -free rAA;~A1s, and subsequently reacting the copolymer 10 contA;n;ng acid anhydride groups which has formed with ~ '' . .;.. ~.
A) in the temperature range from 60~C to 160~C, preferably from 100~ to 120~C, catalysts being used if desired. In this preparation process, it must be ensured that organic solvents which are inert toward acid anhydride groups are selected both in the prepara-tion of the copolymer and in its reaction with the epoxy and/or ph~nQYy resin. This preparation process is not ~uitablo if --t -r ~ ent C) i8 OH-cont~in;ng monomers.
In this preparation process, the cho;ce of ~olvent is thu~ limited both in the copolymerization carried out first and in the subsequent reaction of the anhydride groups of the copolymer formed with the seco~Ary OH yLO~p8 from A), since the solvents used must be inert toward acid anhydride groups. ~t.._ver, the last-described preparation process is less sensi-tive to the risk of gelling.
The first-described preparation process is more advantageous for economic reasons, since, in an appro-r~.

!~ ;s ' ~ t S
,.;

priately desiqned reactor, the manufacturing process can be carried out continuously from a possible epoxy upgrade to a dispersion step in water without it being necessary to handle inte ~ tes formed in between.~In addition, this process offers greater latitude in the choice of organic solvents. This proves to be particularly advantageous in the preparation of aqueous dispersions. In the first-described process, a lower solvent requirement is only necessary, if at all, for the first process step, which contain~ the reaction of A) with B). Even in the case of relatively high- and high-molecular-weight epoxy resins and ph~nsYy resins, a solids content of from 80 to 95% can be used in this first step.
A further preparation process, but one which is not preferred, comprises reacting component A) with a mixture of ~) and C) in a one-step process. In this preparation process, which is preferably used in the case of phsnnyy resins as component A), the free-r~cAl copolymerization and the reaction of seco~Ary OH y GUp~ of A) with the cyclic anhydride ~.vu~8 of ~) proceed substantially simult~neo~l~ly. Natur_lly, only solvents which are inert toward anhydride yLoups may be used in this preparation process.
It is possible, and in some cases also desired, for some or all of the epoY;~e group~ of the epoxy resin which can be employed as component A) to have been reacted with a compound which i3 reactive toward epoxide groups. In this way, the properties of the ~ ?i', ~''', ~ ~'. ~,; i ~ : . , 2 1 3 " ~

graft copolymer can be controlled. Suitable compound~
which are reactive toward glycidyl g~oups are, for example, saturated - oc~boxylic acids andlor ~henol;c compounds, ~uch as, for example, acetic acid, benzo;c acid, saturated fatty acids having 6 to 18 c~rhon atoms, such as, for example, palmitic acid, lauric acid, myristic acid and stearic acid, bisphenol A, bisphenol F, phenol, nonylphenol, dodecylph~nol, cre~ols, xylenols and t-butylphenol. Al~o ~uitable are alcohols, such as, for example, octanol, and primary and seco~Ary amines, in particular hydroxylAmines, ~uch as ethanolamine and diethanol; ;ne. In the reaction of the epoxy resin (A) with phenols and saturated carboxylic acids, basic catalysts are generally used; a suitable catalyst for the defunc~
tionalization with alcohols is, for example, boron trifluoride. If the compounds which are reactive toward epoY;~e groups ar~ alcohols or phenols, the blocking of the epoY;~ function iB preferably carried out before reaction with the cArbo~ylic anhydrides (B). If the block;ng agents employed are CArboyylic acids, the defunctionalization sho~ suitably take place before or after the reaction with B), but preferably before the reaction with C). If r ;nes are used as the block;ng agents, the substantial reaction of the epoY;~e groups of (A) can be carried out before or after the reaction with (B) and before or after the reaction with (C), but the reaction i~ preferably carried out before the reaction with component (C).

21~21~
....
.. . .
~ - 17 -The present invention also relates to a process for the preparation of the graft copolymers described above, which is characterized in that the epoxy resin and/or phenoxy resin A) is reacted with the carboxylic anhydrides contA;n;ng at least one ethylen;c~lly unsaturated double bond per molecule B) in an organic solvent at from 60~C to 160~C, preferably at from 100~
to 120~C, if desired u~ing catalysts, and the ethy-le~; CA lly unsaturated ~ 8 C) are subsequently polymerized in the presence of the resultant reaction product in an organic ~olvlent at temperatures of from 60~C to 200~C, preferably at from 120~C to 140~C, using at least 0.5~ by weight, based on the total weight of the monomers B) and C), of initiators which form free rAA;~Als~ it being possible, if desired, for at least some of the epnY;~e groups from component A) to be reacted with compounds which are reactive toward epoxide groups.
The present invention furthermore relates to a process for the preparation of the graft copolymers described above, which is characterized in that the carboxylic anhydrides B) and the ethylenicAlly unsaturated - nr er8 C ) are polymerized in an organic solvent at temperatures of from 60~C to 200~C, preferably at from 120~C to 140~C, using at least 0.5%
by weight, based on the total weight of the -~ B) and C), of initiators which form free rA~;cAl 8, and the copolymer formed i8 subsequently reacted with the epoxy resin and/or pheno~y resin in an organic solvent at i ~, ~ 'r~r ~ -q.~

2 1 3 .~
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- 18 - ~
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from 60~C to 160~C, preferably at from 100~C to 120~C, if desired using catalysts, it being possible, if desired, for at least some of the epo~i~e groups from ' ~
component A) to be reacted with c- _unds which are ~ ;
reactive toward epo~;~e groups.
If all the epn~;~e groups of the graft copoly-mer are reacted, it is necessary to add an external ~:
crossl;nk;ng agent to effect curing.
If the above-described graft copolymers a) have an acid number in the range from 40 to 250 mg of K0~/g, they are readily dispersible in water, and they are suitable for use in aqueous coating compositions.
Howe~e~, they are also highly suitable for use in non-aqueous, solvent-contA;ning coating c -sitions. The present invention therefore likewise relate~ to aqueous coating c~ -sitions which contain water-dispersed binder solutions which contain a) from 30 to 70% by weight, preferably from 35 to 65~ by weight, of the above-described graft copolymers according to the invention, b) from 0 to 30% by weight, preferably from 5 to 16%
by weight, of at least one phenolic and/or amino resin as crosslink;~g agent, c) from 1 to 7% by weight, preferably from 1 to 5% by weight, of ammonia and/or an amine as neutralizer, and :: .
d) from 5 to 60% by weight of organic solvents, where the sum of the proportions by weight of components a) to d) in each case is 100% by weight. If :-~,',.,''".,'i'',~':, ~ . .' 2 ~ '3 desired, further water-dispersible b;n~ers, preferably epoxy resins, can be used in addition to the graft copolymers (a) in the aqueous coating composition~.
Suitable crossl; nk; ng agents b) are any deslred phenolic resins, as long a~ they have the methylol functionality necessary for the reactivity. Preferred phenolic resins are products, prepared under ~lkAl;ne condition~, of the reaction of phenol, sub~tituted phenols and blsphenol A with f~ ehyde. Under such conditions, the methylol group is 1i nk~ to the aromatic ring either in the ortho-position or in the para-position. Preference i8 given to phenolic resins of the resol type which are based on bisphenol A and contain more than one methylol group per phenyl ring.
Typical suitable amino resin~ (component b) are mel~ ;ne, benzoguanamine and urea-fs -l~Phyde resins.
These are preferably used in the form which has been etherified by means of lower Alcohsls, u~ually methanol and/or butanol. FYr, les of suitable amino resins are commercially available under the tr~enr -a Cymel, Luwipal, Maprénal and Beetle. An example of a suitable amino resin is hexamethoxymethylmelamine.
In addition to the con~enC~tion products with formaldehyde, it is of course also possible to u~e those with other aldehydes.
If the graft copolymer a) contains epoYi~
groups, it is not necessary for the coating compo~ition to contain a crossl ink;ng agent b) to effect curing.
The composition i8 thus in this case self-croBsl ink; ng.

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In the case of epo~i~e y-OU~ free graft copolymers a), the use of a crosslinking agent is necessary.
The neutralizers (component c) employed are from 1 to 7% by weight, preferably from 1 to 5%-by weight, in each case based on the total weight of components a to d, of ammonia and/or amines.
Preferred neutralizers c) are triethylamine and/or dimethylethanolamine.
Organic solvents which are suitable as component d) are, for example, monoAlcohols having 3 to 18 carbon atoms, such as, for example, butanol, isobutanol, propanol and isopropanol, pentanol and isopentanol; and glycol ethers, such as, for example, butyl glycol, butyl diglycol, hexyl glycol and 15 propylene glycol. ;~
The solvents used are preferably, at least in part, solvents which are also suitable as cosolvents ;
for the aqueous dispersion, e.g. butanol, butyl glycol ~ ~;
and butyl diglycol. The solvents are usually used in 20 amounts of from 5 to 60% by weight. ; -~
In addition to the h; n~9r solution described, which is usually employed in amounts of from 5 to 60% -by weight, preferably from 15 to 50% by weight, in each case based on the total weight of the coating compo~
25 sition, the coating - ~_sitions may al~o, if de~ired, contain pigments and/or fillers, further assistants and additives, if desired further solvents and water, in each case in conventional amounts.

~ 9 ~

2~'321~ 'J

Pigments and/or fillers are preferably employed in amounts of from 25 to 35% by weight, based on the total weight of the coating composition. Examples of suitable pigment~ are titanium dioxide, for example the products obtainable under the tr~en~ -8 Titan Rutil RN 59, RTC 60, R 900 and RDI-S.
Suitable fillers are barium sulfate, such as, for eYA le, the commercial products Blancfix micro and Blancfix F; silicon AioX;~e, for example the commercial ~; lO product Qua ; - hl SF 600; potassium carbonate and talc.
The coating compositions preferably also contain from 0.01 to 5.0% by weight, based on the total .
weight of the coating composition, of further assis-tants and additives, such as, for example, lubricants, lS such as waxes, plasticizers, stabilizers, wetting agents, dispersion aids, catalysts and surface-active additives, individually or as a mixture. ' The aqueous coating compositions according to the invention preferably contain from lO to 25% by weight of organic solvents and preferably from 20 to 40% by weight of water, in each case based on the total weight of the coating c~ -sition.
If the graft copolymer a) still contains sufficient epoYi~s yLOUp3~ the use of a crosslink;ng agent b) is unnecessary, i.e. the coating c~ ~_sition is in this case self-crossl;nk;nq.
The present invention also relates to the ~-process for the preparation of the ab~v_ described aqueous coating compositions, which is characterized in 21.~

that the graft copolymer a), dissolved in an organic solvent d) is at least partially neutralized by means of ammonia and/or amine c), if desired the cro8~l i nki ng agent b) and if desired further solvent d) and if desired further conventional additives, if desired pigments and fillers, are admixed, and the coating composition iQ dispersed in water.
The graft copolymers described dissolved in organic solvents, are at least partially neutralized by addition of ~ -r;~ and/or r ;ne~. The r --;A and/or amines are employed in an amount sufficient to render the coating c sition water-disper~ible. The neutra~
lization of the organic h; n~r solution by means of tertiary amines is preferably carried out in the temperature range of from 60~C to 120~C. If desired crossl;nking agents b), if desired cosolvents d) necessary for producing a film with qood flow-out, and if desired further cohveh~ional additives and if desired pigments and fillers are admixed. The coating composition is subsequently dispersed in water. It is also possible first to p,ecsn~en~e the graft copolymer, dissolved in an organic solvent, by means of the crossl;n~;ng agent b), this being followed by neutralization, if desired further solvent d) and if desired further conventional additives, fillers and if desired p;~ -nts being admixed, and the coating com-position being dispersed in water.
The coating compositions according to the invention cure at an object temperature in the range $ ~

21~2~0G

from 150 to 400~C for a time of from 2 seconds to 10 minutes. They can be applied by rolling, knife coating, spreading, spraying, flooding or dipping by mean~ of conventional eq~ nt, the film subsequently being oured to given an adherent coating. The coating compositions are, in the case of internal coating materials for cans, preferably applied by spray coating. In the case of external coating materials for cans, they are preferably Appl ie~ by roller coating.
The aqueous coating - ~itions according to the invention can also be applied by Ano~
electrodeposition coating. In this case, the parts to be coated are immersed into an aqueous bath based on the above-described coating - ~-sitions according to the invention and co~nected as the anode. ~y mean~ of direct current, a film iB deposited on the cans, the substrate is removed from the bath, and the film is cured by h~k; ng.
The coating compositions are preferably applied '3 20 as a one-coat finish, generally having a dry film ~h; ~kneB8 of from 5 to 25 lm.
The coating c. ~-sitions according to the invention are suitable for coating packaging con-tainers, in particular for the internal coating of cans and the like. However, they can also be used for the external coating of cans and the like. The pAckAq;ng containers can comprise a very wide variety of materials and have a very wide variety of geometries.
Suitable materials are, in particular, tin-free steel, ~?2la6 tinplate, and variou~ iron alloys, which may have been provided with a passivation layer ba~ed on compounds of nickel, chromium and zinc. The packaging containers can be coated in the form of, for example, can halves, i.e.
bodies and lids, as 3-part cans and as 2-part cans which have been drawn and ironed or deep drawn in another -nn~r ~uch as, for example, beverage and preserved-foot cans.
The aqueous coating c~ -6ition~ have a long~; 10 shelf life, and the coating films pro~ e~ from them have an excellent pLopeLLy level with respect to freedom from pores, contents resistance, adhesion to metal sheeting, hardness, elasticity and flavor neutrality. The resultant coatings have very good pasteurization and sterilization stabilities. In addition, the aqueous coating composition dispersions are very stable, even when high-molecular-weight epoxy resins and phenoyy resins are used, which is possibly attributable to the fact that the high-molecular-weight hydLop~ob;c constituents of component A) of the b;n~r used are modified by the graft copolymerization in such a manner that good water-di~persibility results.
The invention i~ de~cribed in greater detail below with reference to working examples.

21~2~ n6 -- ~5 -Example 1: Preparation of an aqueous d~persion of a~ anhyd~ fied epoxg acrylate re~n 1.1 React$on of as epoxy r~in with a~ ethyle~c~lly un~aturated a~hydr~de 1000 g of a ~olid epoxy resin of type 1007 (Epikote 1007 from Shell) having an epo~;~e equivalent weight of 1751 g/mol are dissolved in 111 g of xylene at 120~C in a four-necke~ flask fitted with stirrer, reflux co~e~cer and thermometer. 5.5 g of methacrylic anhydride (0.55~, based on the ~olid epoxy resin) are added to the epoxy resin solution, and the reactor content~ are kept at 120~C for one hour and then diluted with 193 g of butyl glycol, 223 g of butanol and 45 g of pentanol mixture.
1.2 Acrylatlon of th- r-act~on ~Lvd~_L from 1.1 1568 g of the reaction reaction from 1.1 are warmed to 120~C in a four-necke~ flask fitted with stirrer, reflux co~ er, two metering ve~sels and thermometer. A pre-prepared mixture of 179 g of methacrylic acid, 117 g of styrene and 128 g of ethyl acrylate is metered into the reactor content~ at a uniform rate over a period of two hour~ from the first metering vessel. At the same time, a solution of 10 g of tert-butyl perbsnzoate in 30 g of butyl glycol i~
added dropwise at a uniform rate over 2 1/2 hours from the second metering vessel. When the feeds are complete, the reactor contents are kept at 120~C for a further three hours. The resultant product has an acid number of 80.5 mg of K0~/g and a viscosity of 4.8 dPa ~
(30% strength solution in butyl glycol, plate-and-cone ~ ~ ;
' ,'' !C~.~

viscometer at 23~C) at a solids content of 71%.
1.3 Neutralization of the reactio~ product from 1.2 ~
1990 g of the reaction product from 1.2 are warmed to 90~C in a four-necke~ flask fitted with stirrer, reflux co~enC~r~ metering vessel and thermo-meter. 542 g of demineralized water are carefully added to the binder, and the mixture is subsequently neutralized at 90~C u8inq 74 g of dimethylethanolamine.
The degree of neutralization i8 40%.
1-4 Preparation of an 9 ,~ dispersion of tbe rea¢tlon pr~ rbto~--' from 1.3 .
2606 g of the h;n~sr from 1.3 neutralized by the proce~ describsd are run out of the reactor at 80~C into 4561 g of demineralized water and are dispersed over a period of one hour. The resultant dispersion ha~ a ~olids content of 20% and an efflux time (DIN 4 cup, 20~C) of 35 seconds.
20 ~Y~ le 2~ arat1On of an ?~ Y_ ~ d~spersion of an anhydrld--modif~ed epoxy acrylat-.
r-~in with oub~tant~al ~loc~q of the epQx~ functions by means of benzoic acid befor- the acrylation~5 2.1 Chain exten~1On of an epoxy resin hav~ng an spc i~ eguivalent weight of 1700 663 g of a liquid epoxy re~in based on bisphenol A and having an epo~;de equivalent weight of 187 g/mol and 111 g of xylene are weighed out into a . " ~

~ ~ f ~
.' ', "~ :

four-necked flask fitted with stirrer, reflux co~en~er and ~he - -ter and are heated with stirring. At 100~C, 337 g of bi8phe~01 A and 0.3 g of ethyltriphenylphos-phonium iodide (Shell Catalyst 1201) are added. The reaction mixture iB heated to 160-165~C. The supply of heat is regulated so that the exothermicity which occurs does not allow the temperature in the flask to rise above a maximum value of 180~C. The reaction mixture is kept at 160-165~C until a target EEW of 1700 has been reA~heA, and is then cool~d to 140~C.
2.2 Reaction of th- ~poxy re~in prepared as in 2.1 with an unsaturated CaLLG~yl~ C anhydride 1090 g of the epoxy resin solution from 2.1 are heated to 140~C in a four-neckPA flask fitted with stirrer, reflux cQ~Aenqsr and thermometer. 2~5 g of methacrylic anhydride (0.25 g, based on solid epoxy resin) are added, and the reactor contents are kept at 140~C for one hour, then cooled to 130~C and diluted with 68 g of butyl glycol, 68 g of butanol and 14 g of pentanol mixture.
2.3 ~ a¢tion of th- react~on Q~C~ _ L from 2.2 with carboxyllc acid 1243 g of the reaction product from 2.2 are warmed to 130~C in a four-neck~A fla~k fitted with stirrer, reflux co~A~n~er and thermometer. 58 g of benzoic acid and 2 g of dimethylbenzyli~mine are added, and the reaction mixture i8 kept at 130~C until an EEW
of ~ 10000 g has been reA~heA, is then cooled and is ~.. t~ '. .c~

?

? ~ 7 ?~

-' 2~3213;~ :
.. . . -diluted with 275 g of butyl glycol, 306 g of butanol and 61 g of pentanol mixture.
2.4 Acrylat~on of the react~on product from 2.3 1932 g of the reaction product from 2.3 are warmed to 120~C in a four-necke~ flask fitted with stirrer, reflux con~enRer, two metering ves~els and the - -ter. A pre-prepared mixture of 187 g of methacrylic acid, 122 g of styrene and 134 g of ethyl acrylate is metered into the reactor contents at a uniform rate over a period of two hours from the first metering vessel. At the same time, a solution of 10 g of tert-butyl perbenzoate in 31 g of butyl gly~ol is added dropwise at a uniform rate over the course of 2.5 hours from the seco~ metering vessel. When the feeds are complete, the reactor contents are kept at 120~C for a further three hours. The resultant product has an acid number of 79 mg of XO~/g and a vi~co~;ty of 11.6 dPa 8 (30% strength solution in butyl glycol, plate-and-cone viscometer, D-cone at 23~C) at a solids content of 62%.
2.5 Neutralization of the reaction p~o~L from 2.4 1376 g of the reaction product from 2.4 are warmed to 90~C in a four-necked flask fitted with stirrer, reflux co~Pnqer, metering vessel and thermo-meter. A pre-prepared mixture of 33 g of dimethyl-ethanolamine and 150 g of ~ ;npralized water is metered into the reactor contents over a period of 15 minutes, the mixture i~ then kept at 90~C for a ~ ;

~ ~ A~

CA 02l32l06 l998-04-27 further 30 minutes, and then cooled to 80~C. The degree of neutralization is 30%.
2.6 Preparation of an aqueous dispersion from the reaction product from 2.5 1150 g of the binder from 2.5 neutralized by the process described are run out of the reactor at 80~C into 1192 g of demineralized water warmed to 60~C, and are dispersed over a period of one hour. The resultant dispersion has a solids content of 27~6 and an efflux time (DIN 4 CUp, 23~C) of 60 seconds.
2.7 Preparation of various crosslinked varnishes for LUG caps (twist-off caps) using the dispersion from 2.6 The dispersion prepared as in 2.6 iS tested with the following crosslinking agents in two different ratios (95:5 and 85:15):
Cymel 1123 (American Cyanamid) Luwipal B Oli (BASF AG) Desmodur~ BL 3175 (Bayer AG) Tests for flexibility on club cans, sterilization stability (1 hour at 130~C) and stacking adhesive are carried out. The varnishes are assessed as a system with a white paint.
For each intermediate stage in the overall baking process, the flexibility is assessed separately, i.e. without high-bake (baking process for varnishes), with high-bake *Trade-mark - 29a -(ba~lng process for primers) and without or with baking for a compound material. Sterilization is assessed without and with high-bake.

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.

Example 3: Preparat~on of aD aqueous di~per~ion of an anhydride-modified acrylated p~a-~Yy re~in (~y~ EEW 10000) 3.1 Preparatlon of a ~ y re~in having an epo egu~valent we~ght of about 10000 627 g of a liquid epoxy re~in based on bisphenol A and having an epoY; ~e equivalent weight of 187 g/mol and 166 g of xylene are weighed out into a four-n~ke~ flask fitted with stirrer, reflux con~en~er and the ter, and the mixture i~ heated with stirring. 373 g of bisphenol A are added at 80~C, and 0.5 g of ethyltriphenylphosphonium ;o~;~e (Shell Catalyst 1201) are added at 100~C. The reaction mixture is heated to 150-155~C. The supply of heat is regulated 80 that the exothermicity which occurs does not allow the temperature in the flask to rise above a maximum value of 155~C. The reaction mixture is kept at 150-155~C until an E~W of 10000 g/mol has been reA~he~
and is then cooled to 140~C.
3.2 Reactlon of th- epoxy re~in fro~ 3.1 w~th an ethyl- ~c~lly un~aturated anhydr~de 1138 g of the epoxy resin solution from 3.1 are heated to 140~C in a four-necke~ flask fitted with stirrer, reflux co~n~er and thermometer. 5.0 g of methacrylic anhydride (0.50%, ba~ed on solid epoxy resin) are added, and the reactor content~ are kept at 140~C for one hour, then cooled to 120~C and diluted with 528 g of butyl glycol, 556 g of butanol and lll g of pentanol mixture.

. ' ' ~ ' ;~ '' "' ' "" '' ' '. ' ' " . "' . 't' ' '~' ' ' ' 2 1 ~
- 3~ -3.3 Acrylation of the reaction p~odu~ from 3.2 1953 g of the reaction product from 3.2 are warmed to 120~C in a four-necked flask fitted with stirrer, reflux con~nser, two metering vessel~ and thermometer. A pre-prepared mixture of 175 g of methacrylic acid, 115 g of styrene and 115 g of ethyl acrylate is metered into the rsactor contents at a uniform rate over a period of two hour~ from the first metering vessel. At the same time, a solution of 10 g of tert-butyl perbenzoate in 28 g of butyl glycol i8 added dropwiYe at a uniform rate over the course of 2.5 hours from the second metering vessel. When the feeds are cGmplete, the reactor content~ are kept at 120~C for a further three hours and then further diluted with 137 g of butyl glycol, 137 g of butanol and 28 g of pentanol mixture. The re~ultant ~.odu~L ha~
an acid number of 73.6 mS of KOH/g and a vi~cosity of 5.6 dPa ~ (20% strength solution in butyl glycol, plate;and-cone viscometer at 23~C) at a solids content 3.4 N utrallzation and di~persion of the reaction p~od~c~ from 3.3 1474 g of the reaction product from 3.3 are warmed to 90~C in a four-necked fla~k fitted with stirrer, reflux co~e~er, metering vessel and thermo-meter. 27 g of dimethylethanolamine are run into the reactor contents over the course of 10 minutes, the mixture i8 then kept at 90~C for a further 30 minute~, 1816 g of demineralized water held at 60~C are then ~132~0 ï) _ 33 -added over a period of one hour, and the mixture i8 dispersed at 90~C for a further hour. The degree of ;
neutralization is 30%, and the dispersion has an efflux .. . : -:
time (DIN 4 cup, 20~C) of 27 seconds at a solid~
content of 20~
Examplo 4: Copolymerisation of an unsaturated anhydride with ethyl~n1cAIly unsaturated monomer- and o~ Q.--t reactlon wlth an epo~y re~in ' ~ --10 4.1 Preparation of a ~ p~lymer by copolymerilzation of ~ ~;
methacrylic anhydr~do with ethyl~ ~r~l~y un~aturated monomer~
627 g of methG~y~Lo~yl acetate are ~ to 120~C in a four-necke~ flask fitted with stirrer, ~;
reflux co~en~er, two metering ves~els and thermometer.
~. ~ . ~ ... . ..
A pre-prepared mixture of 10 g of methacrylic anhydride ~1.0%, based on ~olid epoxy resin), 265 g of methacrylic acid, 375 g of styrene and 409 g of ethyl acrylate i~ metered in at 120~C at a uniform rate over a period of two hours from the first metering vessel, and a solution of 27 g of tert-butyl perbenzoate in 90 g of metho~y~.opyl acetate i~ metered in over a period of 2.5 hours from the second metering vessel, both feeds being started ~imultAneo~ly. When the feeds are complete, the reactor contents are kept at 120~C
for a further four hours.

' ~ A ' ~ 21~321i~

4.2 Reaction of the prepolymer w~th epoxy re~
1802 g of the prepolymer mixture from 4.1 are warmed to 120~C in a four-necked fla~k fitted with stirrer, reflux condenser and thermometer. 1000 g ~of solid epoxy resin (Epikote lOD7 having an EEW of 1751 g!mol) are dissolved in portion~ in this mixture, and the reactants are allowed to react at 120~C for a further hour and the mixture is then diluted to a solids content of 70% with 168 g of butyl glycol. The binder has an acid number of 85.3 mg of X0~/g and a viscosity of 1.0 dPa 8 (25% strength solution in butyl glycol, plate-and-cone viscometer at 23~C).
Example 5s Preparation of a~ di~persion of an anhydride-mod~fied epoxy acrylate r-~in with sub~tantial blo~ of the epoY~- fu~ction~ by means of aoetic acid ~-for th- acrylat~on 5.1 ~y~ '~ of an epoxy re~Ln hav~ng an equ~val-nt w ight of about 1700 663 g of a liquid epoxy resin based on bisphenol A and having an epox;~ equivalent weight of 187 g/mol and 111 g of xylene are weighed out into a four-necke~ flask fitted with stirrer, reflux con~n~er and ~h9 -ter, and the mixture is heated with stirring. 337 g of bisphenol A and 0.3 g of ethyl-triphenylphosphon; iodide (Shell Catalyst 1201) are added at 100~C. The reaction mixture is heated to 160-165~C. The supply of heat is regulated 80 that the exoth~ icity which occurs does not allow the rr ' ' ' ! ., - _ 35 _ temperature in the flask to rise above a maximum value of 180~C. The reaction mixture is kept at 160-165~C
until an epox;~e equivalent weight of 1700 has been reached, and is then cooled to 140~C.
5.2 ReactJon of th- epoxy re~n from 5.1 wlth an unsaturated anhydr~d-1106 g of the epoxy re~in solution from 5.1 areheated to 140~C in a four-necke~ flask fitted with stirrer, reflux con~en~Pr and thP -ter. 5 g of methacrylic anhydride (0.50~, based on solid epoxy resin) are added, and the reactor contents are kept at 140~C for one hour, then cooled to 130~C and diluted with 63 g of butyl glycol, 63 g of butanol and 13 g of pentanol mixture.~5 5.3 Réactlon of th- reactlon ~,~a~ ~ fro~ 5.2 wlth carboxylic acld 1245 g of the reaction product from 5.2 are warmed to 130~C in a four-necke~ flask fitted with stirrer, reflux con~e~er and thermometer. 29 g of acetic acid and 2 g of dimethylbenzylamine are added, and the reaction mixture i8 kept at 130~C until an EEW
of > 10000 g/mol has been reAche~, is then cooled and is diluted with 255 g of butyl glycol, 284 g of butanol and 57 g of pentanol mixture.~5 5.4 Acrylatlon of th- r-actlon ~.~3 ~ a~ ln 5.3 1797 g of the reaction product from 5.3 are warmed to 120~C in a four-n~cke~ flask fitted with stirrer, reflux co~n~er, two metering vessels and - 2 1 ~ 2 1 ~ ~
- 36 - ;~
thermometer. A pre-prepared mixture of 172 g of methacrylic acid, 113 g of styrene and 124 g of ethyl acrylate is metered into the reactor contentis at a uniform rate over a period of two hours from the fir~t metering vessel. At the same time, a solution of 10 g of tert-butyl perbenzoate in 29 g of butyl glycol are added dropwise at a uniform rate over the course of 2.5 hours from the second metering vessel. When the feeds are complete, the reactor contentR are kept at 120~C for a further three hours. The resultant product has an acid number of 73 mg of KOH/g and a viscosity of 16.5 dPa 8 (30~ strength ~olution in butyl glycol, plate-and-cone viscometer, D-cone at 23~C) at a solids content of 63%. The reaction mixture is adjusted to a 15solid_ content of-55% with 102 g of butyl glycol, 102 g of butanol and 41 g of pentanol mixture.
5.5 Neutralization of th- reaction ~ from 5.4 2488 g of the reaction product from 5.4 are warmed to 95~C in a four-nPckP~ flask fitted with stirrer, reflux co~enRer, metering vessel and thermometer. 53 g of dimethylethanolamine are metered into the reactor contents over a period of 15 minutes, the mixture is then kept at 95~C for a further 20 minutes and then cooled to 80~C. The degree of neutralization is 30~
'"'''' ~

~: '' ~ 'i' ' ', :;,~;, ' ~ ~ ' ' . ' 2 1 ~ 2 ~ i~J~ 6 , - ,, 5.6 Preparation of an a~,s-_s di~per~on of the react~on product from 5.5 2541 g of the hin~r from 5.5 neutralized by the process described are run out of the reactor at 80~C into 2230 g of ~- ;neralized water warmed to 60~C, and are dispersed for one hour. The resultant dispersion has a solid~ content of 28% and an efflux time (DIN 4 cup, 23~C) of 61 3econ~
5.7 Preparatlon of an ~nter~ial spray coatlng mat-rlal for 2-part bev-rage cano u~lng the dl~pers~on propared a~ in 5.6 83.1 part~ of the aqueous dispersion from 5.6 are adju~ted to a solids content of 25% by means of 2.3 part~ of Luwipal 068 (7%, ba~ed on the solids content of the dispersion 5.6) and 1.46 parts of demineralized water. Testing was carried out in 33 cl steel cans. The cans were ~p,a~ed using the spray-bake/spray-bake proces~ at a rate of 2 * 180 ~g of coating material/can. Two different drying procesqe~ at 215 and 225~C are tested for the bAk;ng process. Test~
were carried out for pasteurization and sterilization stability, porosity, croscl;nk;n~ (MEK te~t), fle~?;h;l;ty (impact sample; nominal ~ 7 mm) and contents resistance (CuS04 test).
The above-described b;ndPr shows an extra-ordinarily good result. In particular, the application properties should be ~ hAFiized~ due to prono~ln~e~
thixotropy of the dispersion.

... ..... ....................................................................... ... ~ -, ~? .' ~ . ?' .. ,~'~,;i'.. ,~ ~, '. ~ g -= 213~1~u Results:
Te3t Result : :

Pasteurization1: ~
5 Water absorption7 +
Adhesion (crosshatch)6 GT O .~.

Sterilization2:
Water absorption7 ++
10 Adhesion (crosshatch)6 GT O

Porosity3 0.7 mA
MEK te~t4 50 double strokes Impact 8~ le 5 mm 15 CuS04 test5 OK
pH 6.97 Solids content 24.7%
Vi~cosity 30 8 DIN 4 -:

1 45 minutes at 80~C in ~ ;n~ralized water .
2 60 minutes at 121~C in tap water 3 Cu/Cd solution, 30 8, 4 V
4 l kg weight 10% CuS04, 10% ~~ ing HCl, 80% water, 24 houre 25 6 crosshatch test with peeling off of Tesa film, : -:
best score = GT 0, worst score a GT 5 7 assessment scale from ++ to --~. 2 1 3 2 1 0 S
- 39 - ~ ~;
Example 6: Preparat~on of an agueou~ di~persion of a~ anhydr~de~ fied epoYy acrylat~
re~ln wlth ~ubffta~tial blo~ g of the ~ . , - -epox~e function~ by ~ean~ of acetic acid ~efore the acrylatio~
6.1 U~y~ ~8 of an epoxy re~in having an EEW of 1700 661 g of a liquid epoxy resin based on bi~phenol A and having an epo~;~e equivalent weight of 186 g/mol and 111 g of xylene are weighed out into a ,; 10 four-necked flask fitted with ~tirrer, reflux condenser and thermometer, and are heated with stirring. 339 g of bisphenol A and 0.5 g of ethyltriphenylphosphonil-m ;o~;~e (Shell Catalyst 1201) are added at 100~C. The reaction mixture is heated to 160-165~C. The supply of heat is regulated ~o that the exothermicity which occurs does not allow the temperature in the fla~k to rise above a maximum value of 180~C. The reaction mixture is kept at 160-165~C until a target EEW of 1700 has been reached, and i9 then cooled to 140~C.
6.2 R action of th- ~poxy re~ln from 6.1 with anhydrid-1101 g of the epoxy resin solution from 6.1 areheated to 140~C in a four-nec~e~ flask fitted with ~tirrer, reflux conA~nRer and thermometer. 8.5 g of ~o~ecenylsllGcin;c anhydride (0.86%, ba~ed on solid epoxy resin) are added, and the reactor contents are kept at 140~C for one hour, then cooled to 130~C ant diluted with 66 g of butyl glycol, 66 g of butanol ant 13 g of pentanol mixture.

- .'' 2 ~ 3 ~ S
,. . . .

6.3 Rea~tlon of the react~on ~l~d~L from 6.2 with carboxylic ac~d 1254 g of the reaction product from 6.2 are warmed to 130~C in a four-necked flask fitted with stirrer, reflux co~n~er and ths ~er. 29 g of acetic acid and 2 g of dimethylbenzylamlne are added, and the reaction mixture is kept at 130~C until an EEW
of ~ 12000 g/mol has been re~ch~, then cooled and diluted with 286 g of butyl glycol, 323 g of butanol and 65 g of pentanol mixture.
6.4 Acrylation of th- rea¢tlon ~ from 6.3 1928 g of the reaction product from 6.3 are warmed to 120~C in a four-necke~ flask fitted with stirrer, reflux co~e~qsr, two metering vessels and thermometer. A ~,e ple~ared mixture of 192 g of methacrylic acid, 156 g of ~tyrene and 170 g of ethyl acrylate is metered into the reactor contents at a uniform rate over a period of two hours from the first metering vessel. At the same time, a solution of 12 g of tert-butyl perbenzoate in 37 g of butyl glycol are added dropwise at a uniform rate over the course of 2.5 hours from the second metering vessel. When the feeds are complete, the reactor contents are kept at 120~C for a further three hours. The resultant product has an acid number of 80 mg of KOH/g and a viscosity of 7.3 dPa 8 (30% strength solution in butyl glycol, plate-and-cone visc~ -ter, C-cone at 23~C) at a solid~
content of 63%.

~,~,~'.,, ,,~,~ ,~i"~

2~321i3 ~
: - "

6.5 Neutra1ization of the reaction produ~t from 6.4 1520 g of the reaction product from 6.4 are warmed to 90~C in a four-necked flask fitted with stirrer, reflux Co~n~ter~ metering vessel and thermometer. A mixture of 37 g of dimethylethanol~ ;ne and 79 g of ~ ineralized water is metered into the reactor content~ over a period of 15 minutes, the mixture is then kept at 90~C for a further 20 minutes, and 144 9 of solid epoxy resin ba~ed on bisphenol A and having an ep~Yi~e eguivalent weight of 1700 g/mol are then added to the neutralized h; nA~r and ~tirred in for 80 minutes until a uniform solution has formed. The degree of neutralization i~ 30%.

6.6 Preparat~on of an -,.P~_~ di~iper~i~on of the react~on ~ from 6.5 2187 g of demineralized water are added at 90~C
over a period of 60 minute~ to 1780 g of the binder mixture from 6.5 neutralized by the process de~cribed, and are dispersed with stirring. Dispersal is then cont;nue~ at 90~C for a further hour, and the mixture is then cooled. The re~ultant dispersion has a ~olids content of 27% and an efflux time (DIN 4 cup, 23~C) of 14 secon~c.

2~32~
~., .

Example 7: Preparation of an aqu~ou~ d~sper~ion o$
an anhydride-~odified epoxy acrylate r0~in with sub~tantial bloc~ n~ of the epoYI~ function~ by mean~ of acet~c acid before th~ acrylation 7.1 Upgrade of an epoxy res~n hav~ng an EEW of 1700 661 g of a liquid epoxy re~in based on bisphenol A and having an epoxide equivalent weight of 186 g/mol and 111 g of xylene are weighed out into a four-necke~ flask fitted with stirrer, reflux co~de~er and thermometer, and are heated with stirring. 339 g of bisphenol A and 0.25 g of ethyltriphenylphosphonium iodide (Shell Catalyst 1201) are added at 100~C. The reaction mixture is heated to 160-165~C. The ~upply of heat is regulated 80 that the exothermicity which , ;. .:. . ~. ..
occurs doe~ not allow the temperature in the flask to rise above a maximum value of 180~C. The reaction mixture is kept at 160-165~C until a target EEW of 1700 has been re~he~, and is then cooled to 140~C.
7.2 R a¢tion of th- epoxy resin fro~ 7.1 w~th ,id-1100 g of the epoxy resin solution from 7.1 areheated to 140~C in a four-necke~ flask fitted with stirrer, reflux co~n~er and thermometer. 8.5 g of ~o~cenylsuccinic anhydride (0.86%, based on solid epoxy resin) are added, and the reactor contents ar~
: -kept at 140~C for one hour, then cooled to 130~C and diluted with 66 g of butyl glycol, 66 g of butanol and '~
13 g of pentanol mixture.

~ ,".,,s,~,"".s~

21~2~ 3 s ;i . '.
! ' _ 43 _ 7.3 React~on of the reaction product from 7.2 with car~oxylic acid 1254 g of the reaction product from 7.2 arewarmed to 130~C in a four-necked flask fitted with stirrer, reflux con~n~er and thermometer. 29 g of acetic acid and 2 g of dimethylbenzylamine are added, and the reaction mixture is kept at 130~C until an EEW
of ~ 9000 g/mol has been re~che~ ~ i8 then cooled and is diluted with 287 g of butyl glycol, 324 g of butanol and 65 g of pentanol mixture.
7.4 Acrylat~on o~ the reaction p~.d ~ from 7.3 1935 g of the reaction product from 7.3 are warmed to 120~C in a four-nec~e~ flask fitted with ~ ~ ' stirrer, reflux con~enqer, two metering vessels and lS thermometer. A pre-prepared mixture of 193 g of ~ m methacrylic acid, 157 g of styrene and 171 g of ethyl .
acrylate is metered into the reactor contents at a uniform rate over a period of two hours from the fir~t metering vessel. At the same time, a ~olution of 12 g of tert-butyl perbe~70ate in 37 g of butyl glycol is added dropwise at a uniform rate over the cour~e of 2.5 hours from the second metering vessel. When the feed~ are complete, the reactor contents are kept at 120~C for a further three hour~. The resultant ~LGdu~
has an acid number of 80 mg of K0~/g and a viscosity of 8.0 dPa 8 (30% strength solution in butyl glycol, plate-and-cone viscometer, C-cone at 23~C) at a solids content of 63%.

.5~ , ~ ., . - ., , 2 1 3 ~

7.5 Neutralization of th- react~on p~od~L from 7.4 1416 g of the reaction product from 7.4 are warmed to 90~C in a four-nec~l flask fitted with ~tirrer, reflux condenser, metering vessel and thermometer. A mixture of 34 g of dimethylethanolamine and 73 g of ~ ineralized water is metered into the reactor contents over a period of 15 minutes, the mixture is then kept at 90~C for a further 20 minutes, and 134 g of solid epoxy resin baeed on bisphenol A and having an ep~Y;~ equivalent weight of 1700 g~mol are then added to the neutralized bin~er and stirred in for :. :.. ..
90 minutes until a uniform solution has formed. The degree of neutralization is 30%.
7.6 Preparation of an ~ o tl~ r~ion of the reaction product from 7.5 2038 g of demineralized water are added at 90~C
over a period of 60 minute~ to 1658 g of the ~;n~r mixture from 7.5 neutralized by the procecs described, and are dispersed with stirring. Disper~al is then cont;nued at 90~C for one hour, and the mixture is then cooled. The resultant dispersion has a solids content of 27% and an efflux time (DIN 4 cup, 23~C) of 14 seco~R.

2 1 c3 ~
, ..................................................................... .
. . .

Example 8: Preparation of an aqueous di~per~ion of an anhydr~ ';fied epoxy res~n with part~al hJoc~ of the apoYi d~ fun~tion by mean~ of benzo~c acid before the acrylation ~ ~
8.1 Upgrade of an epoxy re~n havlng an equi~alent :.<.. 0 welght of about 1700 661 g of a liquid epoxy resin based on bisphenol A and having an epo~;~e equivalent weight of 186 g/mol and 111 g of xylene are weighed out into a four-necke~ flask fitted with stirrer, reflux co~d~n~er and thermometer, and are heated with stirring. 339 g of .
bisphenol A and 0.3 g of ethyltriphenylphosrhs~;um iodide (Shell Cataly3t 1201) are added at 115~C. The reaction mixture is heated to 160-165~C. The supply of heat i~ regulated 80 that the exothermicity which occurs does not allow the temperature in the flask to -~.
rise above a maximum value of 180~C. The reaction -mixture is kept at 160-165~C until an epnY;~
equivalent weight of 1700 has been reAche~, and is then cooled to 140~C. -~
8.2 ~eaction of th- epoxy re~in fro~ 8.1 wlth an ~-un~aturated anhydr~d- :~
1100 g of the epoxy resin solution from 8.1 are heated to 140~C in a four-neck~ flask fitted with stirrer, reflux condenser and the ~er. 2.5 g of methacrylic anhydride (0.25%, based on solid epoxy resin) are added, and the reactor contents are kept at 140~C for one hour, then cooled to 130~C and diluted ?l~?~q'~
:

with 68 g of butyl glycol, 68 g of butanol and 14 g of pentanol mixture.
8.3 Reaction of the reactlon ~ixture from 8.2 w~th carboxylic acid using a pho~phorus catalyet 1252 g of the reaction mixture from 8.2 are warmed to 130~C in a four-nec~e~ flask fitted with stirrer, reflux co~nser and the -ter. 46 g of benzoic acid and 0.5 g of ethyltriphenylphosphonium ;o~ (Shell Catalyst 1201) are added, and the reaction mixture i8 kept at 130~C until an EEW of 5000 g/mol has been re~he~, is then cooled and is diluted with 304 g of butyl glycol, 273 g of butanol and 61 g of pentanol mixture.
8.4 Acrrlatilon of th- roactilon ~ ucL pr-pared a- ln 8.3 1899 g of the reaction mixture from 8.3 are warmed to 120~C in a four-neck~ flask fittet with stirrer, reflux con~n~er, two metering ves~els and thermometer. A pre-prepared mixture of 184 g of methacrylic acid, 120 g of styrene and 131 g of ethyl acrylate is metered into the reactor contents at a uniform rate over a period of two hours from the first metering vessel. At the ~ame time, a solution of 10 g of tert-butyl perbenzoate in 31 g of butanol is added dropwise at a uniform rate over the course of 2.5 hour~
from the second metering vessel. When the feeds are complete, the reactor contents are kept at 120~C for a further three hours. The resultant product has an acid n~ '?r of 86 mg of KOH/g and a viscosity of 9.4 dPa 8 ,, , ~ ' ' ;t i ~' -~ ~"~ ".t~

2~213',3 .i _ 47 _ (30% strength) solution in butyl glycol, plate-and-cone viscometer, D-cone at 23~C) at a solids content of 62%.
8.5 Neutralizat~on of the reaction product from 8.4 2274 g of the reaction mixture from 8.4 are warmed to 90~C in a four-neck~ fla~k fitted with stirrer, reflux condenser, metering vessel and thermometer. A solution of 55 g of dimethylethanolamine in 248 g of demineralized water is metered into the reactor contents over a period of 15 minutes, the mixture is then kept at 95~C for a further 30 minutes, and then cooled to 80~C. The degree of neutralization is 30%
8.6 ~e~ration of an ?~ P~ ~ d~p-rslon of the r-actlon p~ 8.5 2577 g of the b;n~sr from 8.5 neutralized by the proces~ described are run out of the reactor at 80~C into 2560 g of demineralized water warmed to 60~C
and are dispersed over a period of one hour. The resultant dispersion has a solids content of 28% and an efflux time ~DIN 4 cup, 20~C) of 30 ~ec 8.7 Preparation of variou~ cro~ n~1 v~r~ for LU~ cap~ (twi~t-off cap~) u~ng th- di~per~ion from 8.6 The dispersion prepared as in 8.6 is tested) with the following crossl ;nking agents in two different ratios (95:5 and 85:15):
Cymel 1123 (American Cyanamid) Luwipal B017 (BASF AG) , ...*
De~ - lr BL 3175 (Bayer AG) 2~32~i~i) ;

Tests were carried out for the fl~yihility on club cans, the sterilization ~tability (1 hour, 130~C) and the gloss in a system with a white paint.
For each inte -';Ate stage of the overall hAk;ng procegs, the fle~;hil;ty is assessed separately, i.e. without high-bake (bAk;ng proce3s for varn;shes)~
with high-bake (bAk;ng process for primers) and without or with bAk;ng for a compound material. Sterilization is assessed without and with high-bake.
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...

Claims (29)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Aqueous coating composition containing a water-dispersed binder solution which contains a) from 30 to 70% by weight of a graft copolymer, b) from 0 to 30% by weight of at least one phenolic and/or amino resin as crosslinking agent, c) from 1 to 7% by weight of ammonia and/or an amine as neutralizer, and d) from 5 to 60% by weight of organic solvents, where the sum of the proportions by weight of components a) to d) in each case is 100% by weight, wherein the graft copolymer a) is obtainable from A) epoxy resins having an epoxide equivalent weight of at least 500, and/or phenoxy resins, B) carboxylic anhydrides containing at least one polymerizable, ethylenically unsaturated double bond per molecule, and from C) further ethylenically unsaturated monomers, where the ratio between the weight of A) and the total weight of monomer components B) and C) is in the range from 90:10 to 10:90.

2. Aqueous coaling composition according to claim 1 wherein the water-dispersed binder solution contains a) the graft copolymer present at 35 to 65% by weight, b) the phenolic and/or amino resin as crosslinking agent present at 5 to 16% by weight, c) ammonia and/or an amine as neutralizer present at 1 to 5% by weight, and the epoxy resins A) have an epoxide equivalent weight of at least 700.

3. Aqueous coating composition according to claim 2 wherein the ethylenically unsaturated monomers C) include a monomer containing a carboxyl group.

4. Aqueous coating composition according to claim 1, 2 or 3 wherein the ethylenically unsaturated monomers C) are selected from a group consisting of ethyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate, styrene, acrylic acid and methacrylic acid and crotonic acid.

5. Aqueous coating composition according to claim 4 wherein the ethylenically unsaturated monomers C) are a mixture of ethyl acrylate, styrene and methacrylic acid, a mixture of ethyl acrylate, methyl methacrylate, styrene and methacrylic acid, or a mixture of 2-ethylhexyl acrylate, methyl methacrylate and acrylic acid.

6. Aqueous coating composition according to any one of claims 1 to 3 and 5, wherein the graft copolymer a) is obtainable from A) from 30 to 80% by weight of epoxy resins having an epoxide equivalent weight of at least 700 and/or phenoxy resins, and from 70 to 20% by weight of the sum of B) carboxylic anhydrides containing at least one polymerizable, ethylenically unsaturated double bond per molecule, and C) further ethylenically unsaturated monomers, at least some of which contain carboxyl groups, where the sum of the proportions by weight of components A), B) and C) is in each case 100% by weight, from 0.02 to 0.5 mol of component B) are used per mole of component A), and the acid number of the graft copolymer a) is in the range from 40 to 250 mg of KOH/g.

7. Aqueous coating composition according to claim 6 wherein the graft copolymer a) is obtainable from A) from 50 to 75% by weight of epoxy resins having an epoxide equivalent weight of at least 1500, and/or phenoxy resins, and 50 to 25% by weight of the sum of B) and C).

8. Aqueous coating composition according to any one of claims 1 to 3, 5 and 7, wherein the acid number of a) is from 60 to 150 mg of KOH/g.

9. Aqueous coating composition according to claim 6, wherein the acid number of a) is from 60 to 150 mg of KOH/g.

10. Aqueous coating composition according to any one of claims 1 to 3, 5, 7 and 9, wherein component B) is methacrylic anhydride and/or acrylic anhydride, and component C) comprises one or more acid monomers selected from acrylic acid and methacrylic acid, and one or more further ethylenically unsaturated monomers selected from ethyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate and styrene.

11. Aqueous coating composition according to any one of claims 1 to 3, 5, 7 and 9, wherein at least some of the epoxide groups of the epoxy resin A) have been reacted with a compound which is reactive toward epoxide groups.

12. Aqueous coating composition according to claim 11 wherein at least some of the epoxide groups of the epoxy resin A) have been reacted with a compound selected from the group consisting of acetic acid, benzoic acid, palmitic acid, lauric acid, myristic acid, stearic acid, bisphenol A, bisphenol F, phenol, nonylphenol, dodecylphenol, cresols, xylenols, t-butylphenol, octanol, ethanolamine and diethanolamine.

13. Aqueous coating composition according to any one of claims 1 to 3, 5, 7 and 9, wherein the graft copolymer a) has been prepared by either 1.) reacting the epoxy resin and/or phenoxy resin A) with the carboxylic anhydrides containing at least one ethylenically unsaturated double bond per molecule B) in an organic solvent at temperatures of from 60°C to 160°C, if required using catalysts, and subsequently polymerizing the ethylenically unsaturated monomers C) in the presence of the resultant reaction product in an organic solvent at temperatures of from 60°C to 200°C using at least 0.5% by weight, based on the total weight of the monomers B) and C), of initiators which form free radicals, it being possible, if required, for at least some of the epoxide groups from component A) to be reacted with compounds which are reactive toward epoxide groups, or 2.) polymerizing the carboxylic anhydrides B) and the ethylenically unsaturated monomers C) in an organic solvent at temperatures of from 60°C to 200°C using at least 0.5% by weight, based on the total weight of the monomers B) and C), of initiators which form free radicals, and subsequently reacting the copolymer formed with the epoxy resin and/or phenoxy resin A) in an organic solvent at from 60°C to 160°C, if required using catalysts, it being possible, if required, for at least some of the epoxide groups from component A) to be reacted with compounds which are reactive toward epoxide groups.

14. Aqueous coating composition according to claim 13 wherein the graft copolymer a) has been prepared by either 1.) reacting the epoxy resin and/or phenoxy resin A) with the carboxylic anhydrides containing at least one ethylenically unsaturated double bond per molecule B) in an organic solvent at temperatures of from 100°C to 120°C, if required using catalysts, and subsequently polymerizing the ethylenically unsaturated monomers C) in the presence of the resultant reaction product in an organic solvent at temperatures of from 120°C to 140°C using at least 0.5% by weight, based on the total weight of the monomers B) and C), of initiators which form free radicals, it being possible, if required, for at least some of the epoxide groups from component A) to be reacted with compounds which are reactive toward epoxide groups, or 2.) polymerizing the carboxylic anhydrides B) and the ethylenically unsaturated monomers C) in an organic solvent at temperatures of from 120°C to 140°C using at least 0.5% by weight, based on the total weight of the monomers B) and C), of initiators which form free radicals, and subsequently reacting the copolymer formed with the epoxy resin and/or phenoxy resin A) in an organic solvent at from 100°C to 120°C, if required using catalysts, it being possible, if required, for at least some of the epoxide groups from component A) to be reacted with compounds selected from the group consisting of acetic acid, benzoic acid, palmitic acid, lauric acid, myristic acid, stearic acid, bisphenol A, bisphenol F, phenol, nonylphenol, dodecylphenol, cresols, xylenols, t-butylphenol, octanol, ethanolamine and diethanolamine, in the presence of a catalyst if required.

15. Process for the preparation of the aqueous coating composition according to any one of claims 1 to 3, 5, 7, 9, 12 and 14 wherein the graft copolymer a), dissolved in an organic solvent d), is at least partially neutralized by means of ammonia and/or amine c), if required the crosslinking agent b) and if required further solvent d) and if required further suitable additives and if required pigments are admixed, and the coating composition is dispersed in water.

16. Process for the preparation of the aqueous coating composition according to any one of claims 1 to 3, 5, 7, 9, 12 and 14 wherein the graft copolymer a) dissolved in an organic solvent d) is first precondensed with the crosslinking agent b) then at least partially neutralized by means of ammonia and/or amine, if required further solvent d) and if required further suitable additives and if required pigments are admixed, and the coating composition is dispersed in water.

17. Use of the aqueous coating composition according to any one of claims 1 to 3, 5, 7, 9, 11 and 14 for coating packaging containers.

18. Use of the aqueous coating composition according to claim 17 for the internal coating of cans.

19. Process for the preparation of graft copolymers (a) from A) epoxy resins having an epoxide equivalent weight of at least 500, and/or phenoxy resins, B) carboxylic anhydrides containing at least one polymerizable, ethylenically unsaturated double bond per molecule, and from C) further ethylenically unsaturated monomers, where the ratio between the weight of A) and the total weight of monomer components B) and C) is in the range from 90:10 to 10:90, wherein either 1.) the epoxy resin and/or phenoxy resin A) is reacted with the carboxylic anhydrides containing at least one ethylenically unsaturated double bond per molecule B) in an organic solvent at temperatures of from 60°C to 160°C, if required using catalysts, and the ethylenically unsaturated monomers C) are subsequently polymerized in the presence of the resultant reaction product in an organic solvent at temperatures of from 60°C to 200°C, using at least 0.5% by weight, based on the total weight of the monomers B) and C), of initiators which form free radicals, it being possible, if required, for at least some of the epoxide groups from component A) to be reacted with compounds which are reactive toward epoxide groups, with the exception of unsaturated monocarboxylic acids, or 2.) the carboxylic anhydrides B) and the ethylenically unsaturated monomers C) are polymerized in an organic solvent at temperatures of from 60°C to 200°C, using at least 0.5% by weight, based on the total weight of the monomers B) and C), of initiators which form free radicals, and the copolymer formed is subsequently reacted with the epoxy resin and/or phenoxy resin A) in an organic solvent at from 60°C to 160°C, if required using catalysts, it being possible, if required, for at least some of the epoxide groups from component A) to be reacted with compounds which are reactive toward epoxide groups.

20. Process according to claim 19 wherein component A) is defined as epoxy resins having an epoxide equivalent weight of at least 700, and/or phenoxy resins wherein either 1.) the epoxy resin and/or phenoxy resin A) is reacted with the carboxylic anhydrides containing at least one ethylenically unsaturated double bond per molecule B) in an organic solvent at temperatures of from 100°C to 120°C, if required using catalysts, and the ethylenically unsaturated monomers C) are subsequently polymerized in the presence of the resultant reaction product in an organic solvent at temperatures of from 120°C to 140°C, using at least 0.5% by weight, based on the total weight of the monomers B) and C), of initiators which form free radicals, it being possible, if required, for at least some of the epoxide groups from component A) to be reacted with compounds which are reactive toward epoxide groups, with the exception of unsaturated monocarboxylic acids, or 2.) the carboxylic anhydrides B) and the ethylenically unsaturated monomers C) are polymerized in an organic solvent at temperatures of from 120°C to 140°C, using at least 0.5% by weight, based on the total weight of the monomers B) and C), of initiators which form free radicals, and the copolymer formed is subsequently reacted with the epoxy resin and/or phenoxy resin A) in an organic solvent at from 100°C to 120°C, if required using catalysts, it being possible, if required, for at least some of the epoxide groups from component A) to be reacted with compounds selected from the group consisting of acetic acid, benzoic acid, palmitic acid, lauric acid, myristic acid, stearic acid, bisphenol A, bisphenol F, phenol, nonylphenol, dodecylphenol, cresols, xylenols, t-butylphenol, octanol, ethanolamine and diethanolamine, in the presence of a catalyst if required.

21. Process according to claim 19 or 20 wherein the graft copolymer a) is prepared from A) from 30 to 80% by weight of epoxy resins having an epoxide equivalent weight of at least 700, and/or phenoxy resins, and from 70 to 20% by weight of the sum of B) carboxylic anhydrides containing at least one polymerizable, ethylenically unsaturated double bond per molecule, and C) further ethylenically unsaturated monomers, at least some of which contain carboxyl groups, where the sum of the proportions by weight of components A), B) and C) is in each case 100% by weight, from 0.02 to 0.5 mol of component B) are used per mole of component A), and the acid number of the graft copolymer a) is in the range from 40 to 250 mg of KOH/g.

22. Process according to claim 21 wherein the graft copolymer is prepared from A) from 50 to 75% by weight of epoxy resins having an epoxide equivalent weight of at least 1500 and/or phenoxy resins, and from 50 to 25% of the sum of B) and C).

23. Process according to any one of claims 19, 20 and 22 wherein the acid number of graft copolymer a) is from 60 to 150 mg of KOH/g.

24. Process according to claim 19 or 20 wherein at least some of the ethylenically unsaturated monomers C) contain a carboxyl group.

25. Process according to any one of claims 19, 20 and 22, wherein component B) is methacrylic anhydride and/or acrylic anhydride, and component C) is composed of an acid monomer selected from acrylic acid and methacrylic acid and a further ethylenically unsaturated monomer selected from ethyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate and styrene.

26. Process according to any one of claims 19, 20 and 22 wherein at least some of the epoxide groups of the epoxy resin A) are reacted with a compound which is reactive toward epoxide resins.

27. Process according to claim 25 wherein at least some of the epoxide groups of the epoxy resin A) are reacted with a compound selected from the group consisting of acetic acid, benzoic acid, palmitic acid, lauric acid, myristic acid, stearic acid, bisphenol A, bisphenol F, phenol, nonylphenol, dodecylphenol, cresols, xylenols, t-butylphenol, octanol, ethanolamine and diethanolamine, in the presence of a catalyst if required.

28. Graft copolymer which has been prepared by a process according to any one of claims 19, 20, 22 and 27.

29. Coating agent, which contains the graft copolymer according to any one of claims 19, 20, 22 and 27.