Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
7Z~19
~ 1 ~
.
T~01~ 8~/1? 2~:L Dr.K].)./Intl
l~lrdelldbl.e_cation.~c modlEicatl.oll pro_Jl-ctc o~
e~oxy_resi_~s, ~rc~cess _ fo _ pr~dr.~ hem
c~nd their use
rrhe invention rekltes to hardenable cationic
modification products of epoxy resins ~hich contain
as cross-linking princil?les ~-hydroxyallcylcarbarnide
esters and, if appropriate, in addition tertiary
amine ~roups, can be made water-soluble and can
a].so be used in cataphoreti.c electrodeposition
It is Icnown to cross-link epoxy resins ~ith
amines, polyarnino-amides, carboxylic acids~ melamlne
resins, phenol resins, urea resins, the reaction
products of carbamides with carboxylic acids or
dicarboxylic acids and the li~e. Cationic epoxy
resin derivatives usually contain amine groups
whicn, after protonation allow conversion into
an ~queous phase. Such resins can be precipitated
from the aqueous solutions, during cataphoretic
electr~ eæosi.tion by applying direct-current
to electrically conductive substrates. Although
amines and free carboxylic acids cannot be used
to cross-link them, ne~7ertheless it is possible
to use specific ~lyfunctio~al esters of carboxyli.c aci.ds ~or
this purpose. Melamine resins, phenols resins
and urea resins can possibly be used, but these
are usually employed are precondensates. Although
- this e ~ in.~lt el.i~inates disadvantages of the ~roperties
25 - . of t~.e coatings, it never~eless res~llts in
high molecular masses and consequently an increase
in viscocity which is often not desirable.
Self-cross-linking epoxy resin derivatives
are also produced by adding polyisocyanates to ..
3n the hy`droxyl groups or reactive amine groups of
the epo~y resin modification products to a partial
~247;2~3
exkellt: and l~y ,ubs(?qllellt capE)ing. Alcohols Ol
subs~ances wi~l~ amil)e cJroupc; us~ ly serve as clppin-3
ayents It: ;s also possi~)1e to rec-lc~ amine-re~:?
epoxy resil1s or tl1eil deri~ati~t-s wi~ pol~isoc~clllclteG
and/or adc1 Cclt;OniC cJro~pc;l seLv:ing at the same
time as cap}?ing a~ents, to isocyal1ate yroups, f~r
example those re~ainil1g.
In this process carried out on an industr;al
scale, disadval1tages arisc- because the isoeyanates
are difficult to hallc1]e. Tl~ese compounc1s are very
toxic and are sensitive to water and to compounds
containing hydloxyl groups. In the presence of
strong baseg, the isocyanate groups also tend towards
polymerisation. The main d;sadvantage o~ the resins
prepared in tl1is way is, howevel, the high uncapping
temperature; however, cross-linking under practice
conditions is, as a rule, possible from 170C,
but usually only at even higher temperatures.
q~o avoid unclesirable molecular enlaLgemel1t during
the addition of the isocyanate to the epoxy resin,
thosediisocyanates, for example tolylene diisocyanate,
the isocyanate groups of which have different reactivities,
are usually used. The more reactive isocyanate
group reacts with epoxy resin, whilst the ~ore
inert remains, so that molecular enlargement is
avoided in t:his way. This results, in turn, in
- an increase in the disadvan~age of too high stoving
te~nperatures, since the urethanes or substituted
ureas produced from the isocyanate group more inert
in reactive terms are naturally uncapped at even
higher temperatures, so that yet higher cross-linking
temperatures have to be used during the hardening
of the paint. Moreover, during the reaction of
the epoxy resins with diisocyal~ates, hvdroxyl groups
35 of the epo~y resin àre consumed, and these are
therefore no lGnger available for the cross-linking
reaction.
.
~2~7;~:~38
-- 3 ~-
I~ has now been ~ollnd, surpLi.sirlgly, that:
these discldvailtclg~s al.e avoidec1 by tl1e
invention. The subject oE the inverltion i.s harder-lahle
cationic moc1if;.ccltion proc1ucts oE ep.o~y resins
which aLe charact:erised by a content oE ~-h~droxyal~syl
carbamic~e esteL groups, their am~.ide group being
deri~ed frc~m a po1.yamine with at least two primary
and/or secondary amino groups, anc1, op~ioncl~ly,
additionally tc-rtiary alnino groups, of the ni~rogen
bonds of which two are occupied by hydroearbc)n
raclicals, the resins being present as such or in
a form protonated by acid and dissolved in water
or aqueous-organie systems and, if appropriate,
containing conventional additives, and at least
70% of the epoxy groups being reacted.
The subjeet of the invention is also a process
for preparing such modification products, whi.ch
is charaeterised i.n that ~olyami.nes witl1 at least
two primary and/or seeondary amino groups are partially
~0 reacted with eyclie alkylene carbonates to form
~-hydro.~r.yal~yl carbamide ~sters, such ~1at at leas~
one primary or s~condary arnino group remains, and
subsequently the remaining amine functions are
added to epo~y resins, or amine--functional derivatives
of epoxy resins eontaining primary and/or secondary
amine functions are reacted with eyclic alkylene
carbonates to form synthetic resins containing
~-hydroxyal'~ylcar.bamide ester qroups, the epoxy
groups optionally also being reaeted additionally,
- 30 before, during or after their reaetions, with polyamines
eontaining a tertiary and also at least one primary
or secondary amino group.
E`inally, the subject of the invention is
the use of the above-mentioned modi~ication products,
especially those containing either tertiary amino
groups and/or hardenil1g catal~stsr f~r the procluction
VL moulding~, especial.ly surfaee eoatings.
.
:1247Z~38
-- 4 --
Il: is kno~ t:h;1t eycl.;.c al.k~:lerl~? c~r.horlates,
for ex~lnpl.e e~ y].e~l~e ccJrl)ollate, propylelle carbollat:e
or bu~ylelle c~lrbonate, which al e derivatives Oe
l,2-gl.yco:l.s, add themselves to ammonia, ~ri.rnary
amine.:; or secol1dal-y amines ~n~olJ~].y form the
correspondin~ ~ hydroxyal.kyl carbamic1e es~ers.
If polyamines are used, pre~erably t:hose containin~
at least two prlmary al1d/or secolldary ami.ne ~uncticJns~
but preferabl.y at least one pri.mary amine function,
and if the qualltity ratios are chosen so that at
least one amine f~nct.ion, usually a secondary one,
remains, thece adducts can be addecl to the epoxy
groups o~ epoxy resins. Eithex, it is also possible,
for example, to form fi.rst by reacting epoxy resins
with the above-~nentioned polyamines synthetic resins
which contain at least secon~ary and, o.~tionally,
primary amine funetions, and then add the cyclic
alkylene carbonatesO
All epoxy resins containil1g at least one
epoxy group per moleeule can be used as epoxy
resins. The most suitable are polyethers with
epoxy c3ro~lps, es~ecially those with a molecular
weight of 25~-2,500, such as are obtained by etherif~
ication of a bivalent alcohol or diphenol with
epihalohydrins or dihalohydrins, for example
with dichlorohydrin and preferably with epichlorohydrin
in the presence of alkali. rrhese eompoul1ds will
be prepared from glycols~ slleh as ethylene glycol,
diethylene glycol, triethylene glycol, propylene
3 glycol-1~ 2, pro~anediol-1,3, buta~ediol-
- 1,4, pentane~iol-1,5, h~anediol-1,6, and especially
diphenols, such as resoreinol, eateehol, hydroquinor.e,
l,4-dihydroxynàphthalene. Espeelally preferred
are epoxy resins prepared from diphenylo] alkanes,
such as bis ~4-hydroxypherlyl)-methyl--phenylmethane,
bis-(4-hydroxyphenyl!-tolylmethane, 4,4' dil1ydroxydi--
phenyi and especially 2,2-bis~4-hydroxyp`l-lenyl)-
propane and/o. bis(4 hydroxyphenyl)-methane, or
l~d~7;~8Y~
h iCJ Ile t` lX~l;yp~lC'II~ k ~ e S S IIC' II ct S nC)V a l. (.l k '~ )e l~
sl.litclb~? ~ xy le~ ; ar~ r~l?~ y c~ .Yi.~ t:i.or
o~ ~1Oub:l.e bc)nc1s, ~OI~ exalnple, by epoxi(1clti.c~ll o~
~l~sat:uL.1~ed fat:t:y oil.s or ul1saturatec1 hydrc)Garbonc3.
Used for preparing ~--hyc1roxy allcyl carba~ll;.de
esters are, for example, polyamines ~ith hydrocarbon
rac1i.ca~s of 2 to ~ Cal-bOIl atOlllS, suc'h as ethyl.c~l1e-,
I?.].C~py~ tvl(?ne ~m('l l~ s~ d:Lc~n:irl~, cljlg '1'11?'-C'i,'"~l"'''C'-
triamine, tripropy].ene--tet:ramirle, dibu~yle~e~-t:~:ialnil1e,
dihexylene-triami.l1er aromatic amines wlth alipl1atically
bound Nl12 giio~ips, SUCll as xylylel1e~diaJnine and
its hyclration productsr the various cyclollexylenediarnil~es,
but preEerably dialkylene-tri.amines and/or trialkylene-
tetraminer the alkylene radical o~ which contai.r1s
in each case 2 to 6 carbon atoms, especially diethylel1e-
triamine anc1/or tri~thylene~tetramine or mixtureC;
of tlese amines. It is possib].e to maslc son~e of
the ~rimary amine functions. This is efected
appropriately by reaction ~7ith ketones to ~orm Schi.ff's
bases.
The epoxy--resil1 ~-hyclroxyalkylcarbamide es~er
aaducts pre~pared in this way are~alreacly cationic
resins and can be converted wi~h acids into
a water~soluble form. However, the base strength
of the amine grouping contained in~these r~sins
is usua].ly weak. To reinforce the cat;.onic character,
it can therefore be appropriate to incorporate
stronger ami.ne ~unct.ions. For this pu~po.se, it
is advantageous not to react all the epoxy groups
with the all;ylene carbonate adduc:ts, but to reserve
some for further reaction with those ami.nes and/or
alkanol amines which contain, in a~dition to the
primary and/or second amine functions, a tertiary
amine funct.ion.. These are,~for example, dialkylamino-
all;ylamines, especialy dimethyla,ninopropylamine,
N,N-dialkylamil)o-(N'-alkyl)alkylamir1es or N,~--c1ialkyl-
amino~ '-alkallol) alkylarnines, ~or example, N,l~-
dimethylamino-~N'-hydroxyethyl)propy:lamille~ These
.
7~8
G
~mir~ can c~ 3~ l.t~lt~ .i.r~ ~lla
as i.~3 ~ .3(~ Jli (?~.LI~ ll M,t~ L~ ?t~ cllllL
met:hyl.lrnillo)-;~ h~-.lro~yl?l opyl.:"~ le. :In this way,
mc~d;.ricat:ioll p)o(luct:s contc~ lincJ aclclition;l:l.l.y terti.iry
am:irlo group..;, of the ni~rogel~ l~onds o~ ~1hicll two
are occupied by hyclLocaLhorl radi.<1als, are obt.a:irled.
Anotller possibill.t~ of incLecls:irlg the catic~ni.c
proper t:ie9 .i.,S t:o reacl: ~he 13-1-1yclLoxya:l.lcy:l.cclrbarr~ 1e
ester c~roup~3 witll ~hose co~npourlds which collt:aill,
in addition to at l.east one tertiary ami.no group,
at ~east one primary ancl/or secondary ami.no group
alld/or hydro~yl groupO IJrea and/or urethalle groups
are obtained in th~.s way frorn the ~-hydroxyalkylcarbcllnide
ester groups, with molecular enlargement and splitting
Off of glycols~ Among othersr the polyamines listed
above are suitable for this purpose. ~Iowe~er,
it is also possible to use those compounds which
- contain, in addit.ion to at. least one tertiary amlno
grollp~ only hydroxyl groups as functional groups.
Examples oE such compounds are N,N-dialkyl.amino--
(N',l~'-dialkallol)~alky].clmines or po].yethers which
are produced by reacting amines, containing, in
additlon t-o at least one tertiary amino grQup, at least
one prin~y a.nd/or seconda~c~n~lo groupl wit.h alkylene ox.ides,
preferably propylene oxide.
To vary the solubility and to
. adjus~ the correct ~te~t oE hydrophilia or hydropl-lobia,
it is also possible to incorpora~e in the resin
those am~ne adducts of mono~ullctional epoxy compounds
which contain at l.east one primary or secondary
amino group. Such amine adducts can be prepared,
for example, by reacting polyarni.nes, containing
at least two non-tertiary, pre~erably two primary
arnino groups in the ~nolecule, with a) glycidyl
esters of saturat.ed and/or olefInica]-lv unsaturated
fatty acids and/or b) optionally substituted al.kylene-
oxides such as aryl or alkylglyci.dylethers~
For the same purpose, it is possible to incorporate
.
~z~728~
_. 7 _.
' LC'.S:i:l Cllellii.C~ .,y 01~ .'3i(.'~ J.y pC)I.yc~ lC~
ami.c1cs ~hi.c!l ~ollt:a~ at least one prllrl;.lr:y allc1/c-r
secolldary arni.lle f~lln('t,i.C.)!I. The~ polyclmino arni.(les can
be plepared l.~y reactil-lg sat:~1ra~e~ o.r olef:~lica].1.
S unsaturated mono- or po~.ycar~oxylic ac;.ds with
polyfunctiollal. amide.c., for exall1E)le those Ineiltlonec
above.
~ 1~ r~ .ol1})et.~ lcycl:i.c al~v~ ccl.r~ clt~ d~lL~!ln(~ c.~n
take p.1.ace:i.l1.s~.~sL-a~!ce/:i..e.:LIl W1e absenca o~ ':.O1Vt'll~, OJ^ :ill C)rCJ~UliC'
or aqueous sol.u~i.ol1. It proceec1s at room teil1pelature,
b~t in this case requi.res seteral. days. It is
pre~erable to work at el.evated temperatures, pre~erabl.y
at 40 to 120C, especi.ally between 60 and 100C.
~t the higher temperaturest the reaction is u.sual:Ly
te.r.m~lated ar~tel- half cln hour to appîoximately 5
hours, the same applie~ to the reaction of the
reaction proc1ucts obtained wlth the epoxy resins
and the Gptional reaction with aaditiorlal amino
and/or epoxy compounds. rrhe 1.atter can be carri.ed
Ollt i.n solvents. Monohydric or polyhydric alcohols,
ketones, esters, ethers, partial or cornplete glycol
e~hers, acetals or mixtures of t.hese can be used
as solvents.
To increase the cationic properties of the
resins according to the invention, it is possible
to introduce amino groups additionally into the
resin by reactiny, in a f.irst stage, polyamines
containing at least two amino qroups, at least
one of which is tertiary and the others primary
30 or secondary, or those compounds containing, in
addition to at least one primary, secondary and/or
tertiary amine function, also one or more hydroxyl
yr OUp5, ~artially with polyisocyana~es
and by further.reacting the remai.ning isocyanate
groups, in a second stage, with the OH groups or
any primary or secondary amino groups
of the mod.ified epoxy resln which .r~rstill!æ ~res~t.
'
..
~2472~8
-- 8 --
~ uitable polyisocyanates are, for exam~le
2,~- or 2,~-tolylenediisocyanate, ~ylylel1edilisocyan~te,
- diphenylmethal1e-~,4'-c1iisocyanate, triphenylmethane-
4,4',4"-triisocyanate, polypl~elly3-polymethyleneis~cyanates,
isopho on diisocyanate, hexamethylel1ediisocyanate,
2,2,4(2,4,4)-trim~thylhe~amethylel1ediisocyanate t
methylcyclohexyldiisocyanate~ dicyclohexylmethyldiiso-
cyanate, bis-(3-methyl-4-isocyanatocyclohexyl)7llethane,
2,2-bis-[4~isocyanatocyclohexyl)-propane, the methyl
ester of ]y~ine diisocyanate, hiuret of he~al7lethylenedi-
isocyanate, diisocyanates of dimeric acid~, l-metr.yl-
benzene-2,4,5-triisocyanate, biphenyl-2,4,4'-triiso
cyanate, the teiisocyanate ~rom 3 mol of hexamethylene-
diisocyanate and l mol of water with a 16% NC0
15 content ar.d further compounds containing at least
two NC0 groups per molecule.
-It is possible moreover, to introduce a~ditionally
- amino qroups in the form of partial or complete
reaction products of polyepoxides, for example
20 diepoxidesr on the one hand, and polyamines onthe o~her
~nd, contain~n~ t~r~iary a~ine functiol1s c~nd also second
an~/or ~r~ c~ine furctions, via primary and/or
secondary amino groups still present in the resin
molecule.
Tne weight ratio between the epoxy resin,
~-h~dro~al~yl car~ide ester ~erivativ2 ana, if
appropriate, the ~oth2r compounds can vary ~ithin
~ wide limits. Preferably, at least B0~ and, especially
advantageouslyr at least 90% or at least 95~ of
30 the epoxy groups ha-~e been reac~ed ir ~e ~roaucts acco~
to the invention.
For conversion into a water-soluble form,
the resins according to the invention have to be
protonated. The choice of acid used is basically
35 unimport~nt; however, it is preferable to use low-
molecular oryanic mono- or polycarboxylic acids
which op'ionally contain also hydroxyl groups.
F~r example, fo~mic aci~, acetic acid, p~opionic
:
~12~7Z~38
acid, lactic aclcl, glucorlic acid and oxalic ~cid
may be mentioned. Phosplloric acids, especially
orthopllosFhoric acid and its acid esters, can àlso
be used. The acids can be added before, during
or after resin ~ormation.
The cationic resins accorcling to the invention
àre basically ~elf-cross-linking. They cross-link
at temperatures of at least llO~C, preferably frorn
120C, in as much as these resins are strongly
basic, as is the case especially after the incor~oration
of tertiary amino groups. The cross-linking rate
can be accelerated in these resins by using catalysts.
Metal salts, such as the salts of lead, tin, ir~n,
manganese, cobaltr calciùm or barium, with monocarboY.ylic
acids, for example octoates, neodecanoatesr lauratesr
oleates, stearates and naphthenates r are especially
suitable. The more weakly cross-link only at higher
temperatures; for example from 18QC, and for cross-
linkinq at lower temperatures, for exa~ple from
110C or From 12QC, necessarily require the addition
of-catalys~sr for example those mentioned. Consequently,
it is preferable to use the resins in the form
in which they contain either tertiary amino groups
and/~r hardening catalysts.
The resins a~cording to the in~ention a e
usually solid, but sometimes viscous. They can
be used in substance, solid ones e.g. in ~owder mixt~-es,o~-
as solutions in or~anic solvents for the preparation
of moulded bcdies, particularly sheet-like ~ou1~.inCJS such as
30 bondings and coatings, but also ~or impregnation, ;~
and after cross-linking are hi~hly elastic and
chemically resistant. The special advanta~e of
the resins is -that after the addition o~ acids
they can be convel-ted into a water-soluble form
and can be used as aqueous or organo-aqueous colloidal
systems. They can ~e used according to the methods
conventi~nal in paintin~ by being coated, rolled
scraped o~ sprayed on. ~owever, the aqueous or
~2~728~3
a~ueous-organic synthetic resin solutions can also
be used in cataphore LiC e:Lectr~1eF~sition an~
can be precipita~ed by means oE an e:Lectrical current
To allow the resins accorcling to the invention
to be used as paint, that is to say for producing
coatings, the resins present in substance, as
solutions, aqueous-colloidal solutions or dispersiorls
can be provided with pigments, fillers or orher
conventiona1 addit~ es. By additives are meant
in particular those organic substal-ces and synthetic
resins which are llsed in painting to impro~7e the
~ro~r~ s o the coatinas. T~ese are, for e~a~ple, e~
resins, epoxy resin dispersions, ester resins~
polygl~col ethers, non~volatile or not easily volatilised
solvents. These substances can tnemselves ha~e
cationic properties~ but this is noL- imperativeO
Th~ resins accor~ir.g to the invention are
used for producing ccat~1gs on substrates,
ha~/ina a thermal stability whlch
~0 is above tl~e cross-linking temperature. When cataphoretic
electro~e~osition is carried out, the s~bstrates
must ~e electrically conductive, e.g. they consist of me;tal.
In the following Examples, T means parts
by weight and ~ means percentages by weight. Tl1e
~5 viscosit~ is determined, in the form occurring,
at 20C according to DIN 53015.
.
~z~728~
- Examples
i. 332.~ T of an epoxy resill c~erived fl-G~ di~ y]ol
propane arlcl epichloroh~drin, with an epo~y eq-livalellt
wei~ht of ~75, were disso~ved in 221.G T of rnethylethyl
ketone. In another vessel, 77.3 T OL diethy].el-e
triamine were clissolved in 225 T of ethyl acetate
and -~6~5 T of propylene carbonate were added to
tl)e solution maintained at 40C. The prepalation
heated up to approximately 80C as a result oE
tl,e exo.l-ermic reaction. This temperature was
maintained for 3 hours. Subsequently, the reaction
solut;on was transferred from the second reactlon
vessel into the first reaction vessel and the mixture
was stirred for 3 hours at 80C. 933 T of a 60~
resin solution having a viscosity o 15,000 mæa.s
were obtained.
lO0 T of this resin solution were mixed with
2 T of a leacl octoaté solution containin~ 27% leadt
and this paint wi~h a wet-film thic~ness of lO0 ~Im
~as coated on 5 glass plates. After being ventilated
for-30 minutes, these were heated for 30 minutes
each at 130, l40, 150, 160 and 170C in a drying
cup~oard. ~hen cut with a knife, all the paint
films proPed to be tou~h and elastic and~re resistant
25 to solvents~ They passed the acetone tést (double-
wiping a hundre~ times with a s~ab soaked in acetone).
lO0 T of the paint solution mixed with lead
octoate were diluted with methylethylketone to
a viscosity of 15 DI~-s and galvanised iron sheets
30 were ~ip_coate~ with it. The films heated
f~r 20 minutes at 130C in a drying cupboard were tough and
elastic, withstood impact indentation of
70 in~lb and resisted in parallel tests for 30
minutes 2% caus~ic soda at 80C and 2% acetic acid
35 at lOQC.
2. 380 T of an epoxy resin based on diphenylol
propane and epichloro!lydrin, with an epoxy eqllivalent
weight of 95Q, were dissolved in 253.2 T of ethyl
r
~247288
- 12 -
acetate. l:n anotiler reaction~vessel, 20.6 T of
diethy]ene ~riamine we)-e clissolved ln 40.8 T oE
ethylacettte a1ld ~0.7 T o~ propylene carbonate
were added to the mi~ture at room telnpe~ature.
5 It was heated to 80C using the exothermic reaction
and this temperature was maintainecl for 3 hours~
The reaction mixture was then transferrecl from
the second reaction vessel into the flrs~ reaction
vessel and the mi~.ure was stirred for 3 hours
10 at 80~C. It was then cooled to 40C and 16.8 T
of N,~l-dimethylamino-(N'-hydroxy-etl-lyl)propylamine
were added and stiLred at 60C until the preparation
had reache.l the visc~sity of 130,000 mPa.s. q'hls
continued for 4 hours~ The solution was diluted
15 with 150 ~ of methylethyl ketone to 50~. This
solution had a visccsity of 13,000 mPa.s,
- 200 T of thc 50 ~ solution werenuxed with 5 g
of 50~ acetic acid and diluted with 240 T of wateL~
A colloidal solution having a viscosity of 230 mPa.s
20 was obtained. This paint solution ~as coated by
rolling on deg~eased tin-plated sheet steel ancl
cross-linked for 20 minutes at 130C. The thickness
of the stoved paint film was ~ ~tm.
The test pieces wiLhstood impact indentation
25 o~ 70 in/lb without damage and resisted in paralle]
tests for 2 hours a 2% acetic acid at 100C and
2 hours a 2~ ca~tstic soda at 80C.
3. In a reaction vessel provided with a s~irr~r
and a tlermometer 2Q6 T of diethylène triamine
30 were dissolved in 409 T of diethyleneglycoidimethylether
and 408 T o~ propylene carbonate were added at
50C. The temperature rose to 80C and was maintained
at 80C for 3 hours. The reaction w~s then--ten~ated.
1023 T of a solution 1 having a solidscontent of
35 60% ~1 h~l35C) were obtained.
396 T o~ the glycidyl ester of isononanic
acid were dissolve~ in 60 T of diethylen~l~7col
dimethylether, 140 T of hexamethylene diamine were
.. ~ ? . ~
7288
- 13 -
added, and the mixtnre was heated to 1~0C for
2 hours in a r~action vessel provided with a tllermometer
and a stirrer. It was then coole~l. 596 T o~
a 9~ solut1on II were obtained (resi~ e~ /135C).
760 T of an epoxy resin based on diphenylo]propane
and epichlororly~rin, with an epo~y equivc-l~en~wei~3ht
of 475, weLe dissolved, in a reaction vessel provided
with a sti~rer and a thermometer, in a mi~ture
of equal parts of 1,2-propy]ene glycol, methylisoamyl
10 ~etone and diethylbenzene alld were brought to 80C.
272 T of the solution I and 15~ T of a solution
II weLe then ad~3e~ and the mixture sYas stirred
for 3 hours at 80C. 334 T or methylisoamyl ketone,
15.4 T of acetic acid and 2~.5 T of dimeth~laminopropyl-
15 amine were added and stirring was carried out for
- a further 2 hours at 80C. After cooling to 20C,
a 60% solution III of a synthetic resin dilutable with
- water, with a viscosity of 22,000 mPa.s, was
obtaine~.
To prepare a cataphoresis bath, 200 T of -
the solution III were diluted, Wit]l stirring, t~ith
800 T of deionised water. The aqueous-colloidal
solution had a pH value of 8.8 ancl a conductivity
of 463 ~S (microsiemens) (both values measured
25 at 20C). By the addition of 1.3 T o~ acetic acid,
the bath was adjusted to a conductivi~y of 1,200 yS
and a p~ value of 7.9. In a cataphoresis cell,
a de~reased steel sheet was used as an anode and
a phosphated steel sl~eet was used as a cathode
30 Cataphoretic elec~rcae~osition~ s carried out at 25C
with a ~oltage o~ 2~0 vo~ts and lasted for 1.5
mins. The sheet connected as a cathode was taken
from the cell and rinsed with t~ater. After the
sheet had been.aried with an air jet, the coating
35 was stoved at 130"C for 20 minutes ;n a circulating-
air drier. ~ h~ oss~ tou~h c~nd ~las-tic coa~in~
t~ith a layer thickness of 21 ~Im formed on the front
and rear sides. The stoved filln was resistant
lZg~7Z88
to orqanic solvents and passed the acetone tes~.
720 T of solution III~ere rubbed ~;th 108
T of titani~lm cl;o~ide ancl 3.~ T o~ lead sillcate
on a ~-ree-Fol]er device and ~ilutecJ ~ith :~ono T
o~ deionised water. The aqueous-colloidal solution
had a p~ val-lQ of 8.9 and a conductivity of 830 ~IS
(both values measured at 20C). By the addition
of 0.9 T of acetic acid, a p~I value of 7.5 and a
conductivity of 1250 ~uS were set. The pig~nted
resin solution was precipitated in a cataphoresis
cell at 25C, in the same way as above, ~ith a
voltage of 23Q volts. ~fter rinsing the cataphoretically
coated sheet and drying with conp-essed air, stovin~
was carried out for 20 minutes at ],5C in a circu]ating-
air drier. The layer thickness on the frontand rear sides was 19 ~Im.
The Erichsen cuppin~ test according DI~ 53156
pro~uced a ~alue o~ 5.8 n~and i~t ~dertation (~ ac-t s~en~
according to ASTM-~-2794 gave the value of 25in/lb.
In the salt-spray test according to ASTM-~3-117-
64~5Q~ common-salt solution at 35C, the test sheets
showed no signs of under-rusting either on the
edge or a~te--cr~cial incision after an ex~osure tim~
o~ 500 and lOOQ hours. The degree of bubbling
of the test shee~ according to DIN 53209 showed
the best possible value M O G O.
