Note: Descriptions are shown in the official language in which they were submitted.
~ --` 1 328888
` HOECHST AKTIENGESELLSCHAFT HOE 87/F 295 Dr.ZR/A~
Description
Curing component, and the use thereof
S The curing of polyol res;ns using polyisocyanates ;s
~; kno~n. Some of these systems have proven very successful,
`~ and some also have so-called cold-curing properties.
For environmental protection and industrial safety rea-
' 10 sons, however, it is des;rable to have available
isocyanate-free surface-coating systems ~hich, taking into
account economic factors, cure as far as possible at room
temperature and give high-quality coating films.
An isocyanate-free surface-coating system, based on the
Michael addition, is known, for example, from German
Patent 835,809. In this, substances which contain at
least two methylene or methine groups activated by
electron-~ithdrawing groups ~inter alia acetoacetates,
acetoacetamides and cyanoacetates) are empLoyed as CH-
active compounds tMichael donors). Compounds which con-
tain at least two double bonds activated by an electron-
~ithdrawing group ~inter a~ia esters or amides of acrylic
acid and/or methacrylic acid) are used as unsaturated
- 25 substances (Michael acceptors). In practice, ho~ever,
relatively high temperatures are necessary for complete
; curing of the above systems.
,, .
The same curing principle is used in EP-OS 161,679, where
malonic ester group-containing oligomers or polymers func-
tion as CH-active substances. At room temperature, how-
ever, the crosslinking reaction aga;n proceeds relatively
slo~ly here; after one day, the films still have inade-
quate chemical resistance and hardness. A similar dis-
advantage is exhibited by the binder system in US Patent~,408,018, uhich is likewise based on the Michael addition.
'r
- 2 - t 32 8 8 8 8
An aLternative curing principle is used in the condensa-
tion of silanols, which form during curing of silicon-
~ containing polymers whose hydrolysis-sensitive groups on
- the silicon atom react with atmospheric moisture; in this
respect, cf., inter alia, EP Offenlegungsschrifte~ 50,249,
159,716 and 182,316. The relatively complex preparation
of the silicone-conta;ning start;ng compounds and the
dependency of the properties of the coating films on the
relative atmospheric humidity are disadvantageous in this
system. In addition, the polycondensation may commence,
under the influence of atmospheric moisture, even before
processing of the surface-coating material, which results
in skin formation or in precipitation in the coating
material.
'. 15
Similar problems are also exhibited by the system of EP
~ Offenlegungsschrift 34,720, which is based on an oxazoli-
- dine group-containing acrylate resin, where water or
atmospheric oxygen are likewise used as curing agents.
Finally, in German Offenlegungsschrift 3,541,140, a curing
product made from olefinically unsaturated compounds as
s binders and hydrogen-active compounds having a methanetri-
monoamide structure as curing agents is described. A
disadvantage is that relatively large amounts of polyiso-
cyanates, which are hazardous to health, are required for
the preparation of the curing agents. In addition, the
carboxamide group-containing curing agents are not in all
cases perfectly soluble in the customary surface-coa~ing
solvents. A further disadvantage is the great scratch
- sensitivity of the films, which is probably attributable
;~ to the fact that, due to the preparation process, the
curing agents still contain relatively large amounts of
unreacted malonic esters, which do not react with the ole-
finically unsaturated binders.
There is therefore a demand for an isocyanate-free, cold-
curing system which does not have the disadvantages above
and which results in cured products the propert;es of
:
-- 1 3 2 8 8 8 8
- 3 - 20731-1122
..
which compare well with the known isocyanates-containing systems.
~, The invention therefore relates to a curing component
(A) containing active CH groups, which contains at least two
groups of the formula (I)
~ X
'~ CH-A- (I)
s
: ,~ Y
..~
or structural units of the formula (I') or (I")
t X' - CH - A' 3 (I') { X' - CH - A'~
. ..
`~` O O Y
; in which: A denotes C or C-O, the latter group being bonded to
x~ 10 the CH group via the carbon atoms; X and Y are identical or
.~, O
different and denote R -C, CO2Rl, CN, NO2, CONH2, CONR H or
.~ CONRlRl, where the Rl radicals may be identical or different and
represent an alkyl radical having 1 to 12 carbon atoms, with the
: . ...
proviso that only one of the two radicals X and Y may represent
~"~, the NO2 group; A' denotes C or C-O, where the latter group is
~i bonded to the CH group via the carbon atom; X' and Y' are iden-
O O l
,~ tical or different and denote C-O or C-N, with the proviso that,
when A' and X' denote -COO- the radical Y' is not -CON-, the CH
. equivalent weight of the curing component (A) being from 100 to
5000 and the mean molecular weight being from 1,000 to 100,000.
; In addition, the invention relates to a process for the
~3
1 3 2 8 8 8 8
-- 4 --
preparation of this curing component (A), to curable mix-
tures which contain this curing component ~A), and to the
use of these curable mixtures as surface-coating prepara-
tions, in particular as automobile repair paints.
. S
The number of groups (I) in the curing agent according to
the invention is preferably 2 to 200 and in particular 2
to 10, the larger numerical value relating to oligomeric
or polymeric products and representing mean values here.
, 10
The curing component (A) preferably has the formula (II)
( ~ CH- A) R ( I I )
:~ 15
'J'" in which X, Y and A have the above meaning, R2 represents
:,
2 ll
the radical of a polyol R ~OH)ntA = C-0) or the radical
:, O
R2 of a polycarboxylic acid R2(C02H)n(A = C) and n denotes
at least two, preferably 2 to 200, in particular 2 to 10.
In the case of oligomeric or polymeric curing components,
these numerical data are again mean values.
.. ..
. ~,
Furthermore preferred are curing components which are ob-
tained by transesterification of compounds of the formula
~^ (III) or of the formula (IV)
.,. R10 C R10
~' 30 Ch-A-R (III) l ~CH-A-R (IV)
.~ X R 02C
USiR9 polyols R2(0H)n, uhere X, A and R1 have the above
meaning.
The abovementioned polyo~s R2(0H)n may be polyhydric alco-
hols, preferably having 2 to 12, in particular 2 to 6,
carbon atoms. Examples of these are: ethylene glycol,
1,2- and 1,3-propylene glycol, 1,4- and 2,3-butylene
- 5 - 1 3288 88
glycol, di-~-hydroxyethylbutanediol, 1,6-hexanediol, 1,8-
octanediol, neopentyl glycol, 1,6-cyclohexanediol, 1,4-
bis(hydroxymethyl)cyclohexane, 2,2-bis(4-hydroxycyclo-
` hexyl)propane, 2,2-bis(4-(B-hydroxyethoxy)phenyl)propane,
2-methyl-1,3-propanediol, glycerol, trimethylolpropane,
1,2,6-hexanetriol, 1,2,4-butanetriol, tris-(B-hydroxy-
ethyl) isocyanurate, trimethylolethane, pentaerythritol
and the hydroxyalkylation products thereof, furthermore
7,` diethylene glycol, triethylene glycol, tetraethylene gly-
~;; 10 col, polyethylene glycols, dipropylene glycol, tripropy-
lene glycol, polypropylene glycols, dibutylene glycol,
polybutylene glycols and xylylene glycol. It is also
possible to employ polyesters, which are obtained from or
, using lactones, for example E-caprolactone, or hydroxy-
carboxylic acids, such as, for example, hydroxypivalic
acid, ~-hydroxydecanoic acid, ~-hydroxycaproic acid or
thioglycol;c acid. The index n in the above formula (II)
preferably represents 2 to 4 in the case of polyhydric
alcohols of this type.
~; 20
The polyol may alternatively be an oligomeric or polymeric
polyol compound (polyol resin) ~hose molecular ~eight Mw
(weight average, determined by means of gel chromato-
graphy; polystyrene standard), is usually in the range
from about 309 to about 50,00û, preferably about 5,000 to
'~ about 20,000. In special cases, ho~ever, the molecular
~eight ~ay be 100,000 or more. Suitable oligomers/poly-
mers here are polymerization product, polycondensates or
polyaddition compounds~ ~he hydroxyl number is generally
30 to 250r preferably 45 to 200 and in particular 50 to
180, mg of KOH/g. These OH group-containing compounds
may optionally contain further functional groups, such as
carboxyl groups.
; 35 Examples of polyols of this type are polyether polyols,
polyacetal polyols, polyester amide polyols, polyamide
polyols, epoxy resin polyols or the reaction products
thereof uith C02, phenolic resin polyols, Polyurea poly-
ols, polyurethane polyols, cellulose esters and cellulose
- 6 - l 32 8 8 8 8
ether polyoLs, partially hydrolysed homopolymers and co-
polymers of vinyl esters, partially acetalated polyvinyl
alcohols, polycarbonate polyols, polyester polyols or
acrylate res;n polyols. Polyether polyols, polyester
polyols, acrylate resins and polyurethane polyols-are
preferred. Polyols of this type, which may also be em-
ployed in mixtures, are described, for example, in German
Offenlegungsschrift 3,124,784.
Examples of polyurethane polyols are produced from the
reaction of diisocyanates and polyisocyanates ~ith an
excess of diols and/or polyols. Suitable isocyanates are,
for example, hexamethylene diisocyanate, isophorone diiso-
cyanate, toluyl diisocyanate and isocyanates formed from
three moles of a diisocyanate, such as hexamethylene di-
;socyanate or isophorne diisocyanate, and biurets produced
from the reaction of three moles of a diisocyanate with
one mole of water. Suitable polyurea polyols can be ob-
- tained in a similar way by reacting diisocyanates and
po~yisocyanates ~ith ecluimolar amounts of aminoalcohols,
- for example ethanolamine or diethanolamine.
, . ..
. . ,:
Examples of polyester polyols are the kno~n polyconden-
,~ sates made from dicarboxylic acids or polycarboxylic acids
or ~he anhydrides thereof, such as phthalic anhydride,
adipic acid etc., and polyols, such as ethylene glycol,
~' trimethylolpropane, glycerol etc.
Suitable polyamide polyols can be obtained in similar
fashion to the polyesters by replacing the polyols, at
~` least partly, by polyamines, such as isoPhoronediamine,
'J hexamethylenediamine, diethylenetriamine etc.
Examples of polyacrylate polyols or OH group-conta;ning
poLyvinyl compounds are the kno~n copolymers made from
hydroxyl group-containing (meth)acrylic esters or vinyl
alcohol and other vinyl compounds, such as, for example,
styrene or (meth)dtrylic esters.
1 328888
The polycarboxyl;c acids R2(C~2H)n above where n is pre-
ferably 2 to 4 here may be of an aliphatic, cycloalipha-
t;c, aromatic and/or heterocyclic nature and optionally
substituted, by halogen atoms, and/or saturated. Examples
, 5 ~f such carboxylic acids and der;vatives thereof ~hich
may be mentioned are: succinic acid, adipic acid, suberic
acid, azelaic acid, sebacic acid, phthalic acid, tere-
phthalic acid, isophthalic acid, trimellitic acid, pyro-
mellitic acid, tetrahydrophthalic acid, hexahydrophthalic
acid, di- and tetrachlorophthalic acid, endomethylene-
~ tetrahydrophthalic acid and its hexachloro derivative,
-~ glutaric acid, maleic acid, fumaric acid, dimeric and tri-
-- meric fatty acids, such as oleic acid, optionally mixed
with monomeric fatty acids or cyclic monocarboxylic acids,
such as benzoic acid, p-tert.-butylbenzoic acid or hexa-
i hydrobenzoic acid, and furthermore the products of the
react;on of the abovementioned polyols R2(0H)n ~ith cyclic
carboxylic anhydrides.
- ~a The curing component (A) according to the invention is a
- ~iquid of vary;ng viscosity, depending on the nature of
the Polyol or polycarboxylic acid component, or a solid
~hich is substantially soluble, at least in the customary
surface-activating solvents, and preferably contains less
than 5X by weight, in particular less than 1% by weight,
of crosslinked components. The CH equivalent weight,
which is a measure of the number of groups (I) or struc-
tural units tI')/~II") in ~A), is generally bet~een 100
and 5,000, preferably 200 and 2,000, and the mean molecu-
30 lar weight Mw is generally between 1,000 and 100,000,
preferably between 2,000 and 50,000 ~determined by gel
chromatography; polystyrene standard).
It is also possible to employ mixtures of the above com-
pounds as curing components tA).
uring components ~A) can be prepared by several routes.
Thus, for exa~ple, the synthesis can proceed from com-
Pounds (\~)
.
1 3288~8
-
CH (V)
y~ 2
which are acylated using chlorides of monobasic or poly-
basic carboxylic acids or carboxylated using chlorofor-
mates of monohydric or polyhydric alcohols or nitrated,
and the products thus obtained are if appropriate, trans-
esterified using polyols or transamidated using polyamines.
In the case of nitration, at least one of the two radicals
X and Y must denote the -C02R1 radical, and neither of
these radicals may represent an N02 group.
. ,.,~
,~
., .
Examples of compounds of the formula (V) are: dialkyl
malonates of alcohols having 1 to 12, preferably 1 to 10,
carbon atoms, such as dimethyl malonate, diethyl malonate,
diisopropyl malonate and dioctyl malonate, the correspond-
ing esters of cyanoacetic ac;d, such as, for examPle,
~`~ ethyl cyanoacetate or hexyl cyanoacetate; the correspond-
ing esters of acetoacetic acid, such as ethyl acetoace-
tate; diketones, such as acetylacetone; and malononitrile
or malonic diamides or monoamides.
The compounds (V) are acylated in a known manner using
acid chlorides of monocarboxylic acids having 1-10, pre-
-~¦ ferably 1 to 6 carbon atoms, or using acid chlorides of
~i polycarboxylic acids preferably having 2 to 10 carbon
-~ atoms. Examples of appropriate poLycarboxylic acids are
described above.
For carboxylation, the compounds (V) are reacted with
- chloroformic esters of monohydric or polyhydric alcohols
of the abovementioned type, such as, for example, methyl
chloroformate, ethyl chloroformate or 1,6-hexanediol bis-
chloroformate~
.~-
i For acylation or carboxylation, the compound (V) is
- initially reacted with alkal; ~etal or alkaline earth
aetaL al~ox1des, preter~oly sodiu- al~oxide, potassium
~ `
1 328~88
9 _ _
alkoxides or magnesium alkoxides, such as methoxides or
ethoxides, and the products are reacted with acy~ chlor-
ides (R2tCOCl)m (m ~ 1-200) of monobasic or polybasic
carboxylic acids or with chloroformic esters R (OCOcl)m
of monohydric or polyhydric alcohols. This reaction ex-
pediently proceeds in inert solvents, such as ethers and
; aLiphatic or aromatic hydrocarbons, preferably diethyl
ether, tetrahydrofuran, dioxane, diethylene glycol di-
methyl ether, toluene or xylene, or appropriate mixtures.
In pLace of the above alkoxides, the free metals can, less
preferably, be reacted with (V).
"
The nitration can be carried out, for example, by react;ng
the compounds (V) with fuming nitric ac;d or by ox;dizing
; 15 the correspond;ng nitroso compounds by methods known from
the literature, for example at temperatures from 10 to
25C with or without solvent.
It is necessary to transesterify the products obtained
above using polyols of the type mentioned above in order
to polyfunctionalize the curing component. This trans-
ester;fication, which can be omitted, for example, in the
; acylation of alcohols, is carried out, for example, by
heating the acylated, carboxylated or nitrated compounds
(V) with the polyols, such as polyhydric alcohols, to
temperatures from B0 to 200C, preferably 100C to 160C,
-. and removing the monofunctional alcohol by d;stillat;on,
if appropriate under reduced pressure. The reaction
usually proceeds without catalysts. However, the known
~; 30 esterification catalysts, such as metal salts of organ;c
acids, for example the acetates, octanoates or naphtha-
nates of tin, zinc, lead, iron, copper, chromium and
cobalt, and dibutyltin oxide, may be added in amounts from
0.1 to 1.0X by weight to provide acceleration. Dibutyltin
dilaurate is particularly preferred. Through a suitable
choice of the weight ratio of the reaction participants
in the transesterification, the formation of crosslinked
esters of polyhydric alcohols can be suppressed in favor
of formation of the straight-chain or branched esters
,,.
- 10 - 1 3 2 8 8 8 8
i
desired. In addition, chain terminators, i.e. compounds
- which react in a monofunctionaL manner under the reaction
conditions, such as monoalcohols, monoamines or mono-
esters, ~h;ch are preferably non-volatile, may be added
to the batch for this purpose, and also to l;mit ~he
" moLecular weight.
. .
; ,,
i~ The transamidation using polyamines or polyamino alcohols
^ can be carried out in the same ~ay. Suitable polyamines
~, 10 are, for example, alkylenediamines, such as ethylenedia-
mine and its homologs, or polyalkylenepolyamines, such as
diethylenetriamine or triethylenetetramine, or cycloali-
phatic polyamines, such as piperazine, or polyoxyalkylene-
polyamines. Suitable polyamino alcohols are, for example,
hydroxyethyldiethylenetriamine or bishydroxyethyldiethy-
lenetriamine, or the products of the reaction of cyclic
carbonates ~ith polyamines.
,
In another me~hod of preparing the curing components
- 20 according to the invention, compounds of the formula (VI)
.s R 02C (VI~
,.,,.,~ CH2
X
in which R1 and X have the above meanings, are, in the
~s~ above-described ~ay, transesterified using polyols or
-~ transamidated using polyamines, and these transesteri-
; fication products are subsequently acylated in the manner
described using chlorides of monobasic and polybasic car-
~ .~
boxylic acids or carboxylated using chloroformic esters
of monohydric or polyhydric alcohols or nitrated using
~,
~ nitric acid.
~ '''',
P In the transesterification or transamidation of the com-
35 pounds (VI) or the acylated, carboxylated or nityrated
compounds (V), the reactants are normally employed in
amounts such that at least one hydroxyl or amino group is
transferred to (VI) or to the acylated, carboxylated or
nitrated comcound (V).
.
1 328888
The curing component (A) according to the invention is
employed in curable mixtures together ~ith compounds (B)
- ~hich contain at least t~o groups which are capable of
Michael addition, i.e. groups which contain double bonds
activated by at least one electron-withdrawing group
(Michael acceptor). Suitable compounds (~) are described,
for example, in German Patent 835,809, in US Patent
4,408,018 and in European Offenlegungsschriften 161,679
and 224,158, to which reference is made here.
The compounds (B) preferably contain at least two groups
of the formuLa (VII)
R3R4C = CR4-~- (VII~
in ~hich:
R3 denotes hydrogen or a hydrocarbon radical, preferably
an alkyl radical, hav;ng 1 to 12, preferably 1 to 4,
carbon atoms, such as the methyl, ethyl, n-propyl, ;so-
propyl, n-butyl or tert.butyl group;
R4 are ;dent;cal or different and denote hydrogen, a
` 20 hydrocarbon radical, preferably an alkyl rad;cal, -
having 1 to 10, preferably 1 to 4, carbon atoms, an
ester group C02R1, or a -CN-, -N02-, -S02-, -CONHR -
~ -CONR1R1 or -COR1 group where R1 has the above
`` mean;ng; and
0 0 0
11 11 11 1
B denotes C, C-O, C-N, ~h~re the t~o latter groups are
; bonded to the CR4 group via the carbon atom.
In the R3R4C group above, R3 and R4 preferably each
represent hydrogen.
."
-~ The groups (VII) above are l;nked indirectly to one
another. A suitable ;ndirect linkage here ;s, for exam-
ple, a hydrocarbon radical, but preferably the rad;cal of
a polyhydric alcohol R1(0H)n or of a polyvalent amine or
am;no alcohol. Th;s ;ndirect l;nkage ~ay also be part of
the cha-in of an oligomer and/or polymer, i.e. the groups
(VII) may be present in the side chains of the oligomer
or polymer or form these side chains.
--- 1 328888
- 12 -
In the specific embodiment, the compound (B~ has the for-
mula ( V I I I )
(R3R4C = CR4-A-)mR2 (VIII)
in ~hich R3, R4 and A have the meaning in the formula
(VII), R2 corresponds to the meaning in the formuta (Il)
and m denotes at least 2, preferably 2 to 200.
The R3R4C = CR4-A- group (VII) may be derived, for exam-
ple, from a mono- or polyunsaturated mono- or dicarboxyl;c
acid having 2 to 20, preferably 3 to 10, carbon atoms.
- Examples of carboxyl;c acids of this type are crotonic
i,.
`~ acid, citraconic acid or the anhydride thereof, sorbic
acid, fumaric acid, mesaconic acid, substituted and unsub-
~' 15 stituted cinnamic acids, dihydrolevulinic acid, malonic
`~ wononitrile, ~-cyanoacrylic acid, alkylidenemalonic acid,
- alkylideneacetoacetic acid, preferably acrylic acid, meth-
acrylic acid and/or maleic acid, or its anhydride. The
possible linking of the Michael acceptor to the connecting
, 20 member, such as a polymeric support, via group A, but
t alternatively via the radica~ R4, can take place via
ester, amide, urethane or urea groups.
-~ Corresponding to the above, the groups of the formula
.~ 25 (VII) may be bonded to the radical of a polyol, a poly-
awine, a polyamide or a polyiminoamide, ~here this radical
~' may also be oligomeric or polymeric.
~; ~
,'~f Suitable polyols here are in principle the same as men-
,:
30 tioned above in connection ~ith the Michael donor, i.e.
polyhydric alcohols or oligomeric or polymeric polyol
compounds, for example Polyether polyols, polyester poly-
ols, acrylate resin polyols and polyurethane polyols.
,
35 SuitabLe amino group-containing supports (polyamines) are,
for example, the abovementioned alkylenediamines and the
oligomers thereof, such as ethylenediamine, propylene-
diamine, butylenediamine, diethylenetriamine, tetramines
and higher homologs of these amines, furthermore amino
alcohols, su~h as diethanolamine or the lik~32 8~ 88
~ The examples of compounds (B) which may be mentioned here
- are: alkylglycol d;(meth)acryLate, such as as ethylene
glycol diacrylates, diethylene glycol d;acrylate, propy-
Lene glycol diacrylate, trimethylene glycol d;acryLate,
neopentyl glycol diacrylate, 1,3-butylene glycol diacry-
late, 1,4-butylene glycol diacrylate, 1,6-hexamethylene
glycol diacrylate, 1,10-decamethylene glycol diacrylate,
trimethylolpropane triacrylate, pentaerythritol tetra-
acrylate, pentaerythritol triacrylate and the correspond-
ing methacrylates.
;::
In addition, the acryloxy group may be bonded to polymers,
for example condensation polymers, uch as polyesters, or
polyaddition polymers, such as polyurethanes, polyethers
or vinyl polymers, such as glycidyl (meth)acrylate copoly-
mers. Examples which may be mentioned here are urethane
; acrylates, obtained by reacting polyisocyanates, such as
- 20 hexamethylene diisocyanate, with hydroxyalkyl acrylates,
such as hydroxyethyl acrylate, or by reacting hydroxyl
group-containing polyesters, polyethers or polyacrylates
with polyisocyanates and hydroxyalkyl acrylates, urethane
acrylates, obtained by reacting caprolactonediol or -triol
~ith polyisocyanates and hydroxya~kyl acrylates, polyether
acrylates, obtained by esterifying hydroxypolyethers using
acrylic acid, polyester acrylates, obtained by esterifying
hydroxypolyesters using acrylic acid, and polyacrylates,
- obtained by reacting acrylic acid with vinyl polymers
containing epoxide groups, for example copolymers with
- glycidyl (meth)acrylate or vinyl glycidyl ether.
Mixtures of the compounds above are also possible as com-
ponent (B).
The C=C equivalent ~eight of component ~B) is generally
bet~een 85 and 1,800, preferably bet~een 180 and 1,200,
and the molecular ~eight M~ is generally between 170 and
50,000, preferably 500 and 30,000.
- 14 - 1 328888
The mixing ratio of the two components (A) and tB) depends
on the number of available C-H-acidic hydrocarbon atoms in
the curing component and on the number of unsaturated
groups in the ~,~-unsaturated compounds. Since the reac-
tive groups can be determined titrimetrically, precisestoichiometric mixing ratios can be produced. In general,
' the donor:acceptor group equivalent ratio is 2:1 to 1:2,
'.,!~ in particular about (0.8-1.2):1 to about 1:(0.8-1.2). In
- this ~ay, an adequate crosslinking density is generally
achieved.
In order to accelerate the curing reaction corresponding-
,
ly, the curable mixtures according to the invention con-
~` tain the catalysts ~hich are kno~n for the Michael
!~, 15 addition, in particular Le~is bases or Bronstedt bases.
Suitable catalysts can be found, for example, in European
. Offenlegungsschrift 224,158, to uhich reference is again
made here.
: ..
~'~ 20 Catalysts which may be mentioned here are, for example,
sterically hindered tertiary amines, such as, for example,
1,4-diazabicyclo(2.2.2)octane (DABCO), cyclic amidines,
such as, for example, 1,8-diazabicyclo(5.4.0)undec-7-ene
~ (DBU), 1,4-diazabicyclo(4.3.0)non-5-ene (DBN) inter alia,
3,:~ 25 guanidines, such as, for example, N,N,N,N-tetramethyl-
guanidine, quarternary ammonium salts, such as alkyl-
-~ aryl- and/or benzylammonium fluorides, if appropriate in
combination ~ith tetraalkoxysilanes; examples of quater-
nary ammonium salts of this type which may be mentioned
here are: benzyltrimethylammonium fluorides and tetra-
butylammonium fluoride; in addition, the corresponding
hydroxides and carbonates of quaternary ammonium salts,
such as, for example, alkylbenzyldimethylammonium hydro-
xide, alkyltrimethylammonium hydroxide (alkyl = C16-Cz2),
benzyltrimethylammonium hydroxide and tetrabutylammonium
hydroxide, may be used. The ammonium salts mentioned
can be used alone or mixed or in combination ~ith tertiary
aliphatic amines, such as, for example, triethylamine,
N-methyldiethanolamine etc. further examples here are
:
1 328888
- 15 -
strong bases from the group comprising the metal alkoxides,
such as, for example, lith;um butoxide, sodium methoxide
and potassium methoxide, which can be employed with or
uithout cro~n ethers.
S
~`~ A further i~portant group of catalysts is tertiary phos-
; phines, such as, for example, tris-2-cyanoethylphosphine,
trisdiethylaminomethylphosphine, trisdimethylaminomethyl-
phosphine and trishydroxymethylphosphine, or trisphenyl-
phosphine, tris-p-tolylphosphine, tris-o-anilylphosphine,
phenyldi-o-anisylphosphine, diphenyl-p-anisylphosphine,
diphenyl-o-anisylphosphine, diphenyl-p-dimethylaminophe-
nylphosphine, methyldiphenylphosphine, methylditolylphos-
phine, ethyldi-p-anisylphosphine, (diethylaminomethyl)di-
phenylphosphine or ~,a-dimethylbenzyliminotris(dimethyl-
amino)phosphorane, ~,~-dimethylbenzyliminomethyldiphenyL-
phosphorane, t-butyliminotriphenylphosphorane, preferably
~ -dimethylbenzylimino-tri-butylphosphorane.
:
20 The amount of catalyst is generally 0.01-5Z by weight,
s preferably 0.2-3~ by weight, relative to the total solids
, -
content of the starting material. It may be varied de-
pending on the reactivity of the curing components and on
the pot time and curing duration or temperature intended.
- The curable 0ixtures according to the invention exhibit
pot times which vary, depending on the choice of compound
-- ~A) and (8~ and on the type and quantity of the catalyst
or catalyst combination, between 5 minutes and about 12
30 horus. High processing reliability is thereby ensured.
The curable mixture according to the invention may, if
appropriate, contain a diluent, such as customary solvents
which do not interfere with the Michael addition. The
35 catalyst may thereby be better distributed or its activity
may be increased. Examples ~hich may be mentioned here
are: halogenated hydrocarbons, ethers, such as diethyl
ether, 1,2-dimethoxyethane, tetrahydrofuran or dioxane;
ketones, such as~ for example, methyl ethyl ketone,
:
'
- 16 - 1 3288~8
acetone cyclohexanone and the like; alcohols, such as
methanol, ethanol, propanol, butanol and benzyl alcohol,
(cyclo)aliphatic and/or aromatic hydrocarbons, such as
hexane, heptane, cyclohexane, benzene, toluene, the vari-
ous xylenes and aromatic solvents in the boiling range
from about 150 to 180C (higher-boiling mineral oil
fractions, such as (R)Solvesso). The solvents may be
employed here individually or mixed.
. :,
~' 10 In addition, customary additives, such as, for example,
the customary paint additives, may be present in the cur-
able mixture according to the invention. Examples which
may be mentioned here are: pigments (iron oxides, lead
oxides, lead silicates, titanium dioxide, barium sulfate,
zinc sxide, zinc sulfide, phthalocyanine complexes etc.),
pigment pastes, antioxidants, (UV) stabilizers, flow-
~` control agents, thickeners, defoamers and/or ~etting
~, agents, reactive thinners, fillers (talc, mica, kaolin,
-' chalk, quartz powder, asbestos powder, slate po~der,
: ;:
various silicas, silicates etc.), additional curing agents
and addition curable compounds, and the like. Addition
of these additives to the mixture may be delayed until
just before processing.
In order to produce the curable mixtures according to the
; invention, components (A) and (B) and, ~here appropriate,
additionally the diluent and the additives, are mixed ~ith
one another. In the case of lo~-viscosity components,
this can take place in the solid phase, with ~he mixture
being heated to elevated temperatures if necessary. Higher-
viscosity products, if the curable mixtures are not to be
^~ employed as po~der paints, are dissolved or dispersed in
the diluents mentioned before mixing.
Curing of the mixtures according to the invention pro-
ceeds very quickly and generally takes place at -10 to
1Q0C, preferably 0 to 80C. for example, products of
good hardness are obtained after 8 to 24 hours at room
temperature or after only 0.5 to 1 hour at 60C.
~,~
.~
,
" . ,
-- 1 3288~8
- 17 -
The curing reaction can be carried out in one step, for
example by working ~ith equivalent proportions of compo-
nents ~ and (B). The pot time and the properties of
~- the product depend here on the process conditions, i.e.
on the ~yPe and quantity of the starting materials, the
~etering rate of the catalyst, the temperature program,
etc. ~h~s, the elasticity of the crosslinked product can
be controlled ~ithin a tolerance range, for example by
means of the chain length of the oligomers and/or polymers
employed for (A) and (~). Although curing is generally
carried out batchwise, the scope of the inventionalso
includes carrying out the mixing of the components and
the performanee of the reaction continuously, for example
by means of an automatic painting machine.
; As a consequence of their favorable properties - above
al~ the rapid curing, even at low temperatures and even
at high atmospheric humidity, and the high pendulum hard-
ness, the high gloss and the good chemical resistance of
the coatings - the mixtures according to the invention
have a w;de var;ety of appl;cat;ons in industry, for ex-
ample for the production of moldings (casting resins) for
tool construction or for the production of coatings and/or
intermediate coat;ngs on a ~ide variety of substrates,
for example on those of an organic or inorganic nature,
such as uood, ~ood fiber materials (wood sealing), tex-
tiles of natural or synthetic origin, plastics, glass,
ceramics, building materials, such as concrete, fiberboard,
synthetic stones, but in particular on metal. In addi-
t;on, the mixtures according to the invention can beemployed as components of adhesives, cements, lamination
resins, synthetic resin cements and, in particular, as
co~ponents of pa;nts and surface coatings for coating
industrial objects, househo~d app~iances, furniture and
in the bui~ding industry, such as, for example, refrigera-
tors, ~ashing machines, eleGtrical appliances, ~indo~s
and doors. Application can take place in a kno~n manner,
such as by brushing, spraying, dipping or electrostatically.
:
- 18 - 1 328888
A preferred field of application for the mixtures accord-
- ing to the invention is in the production of automotive
paints (base coats and/or top coats) and in particular of
aùtomobile repair paints. In this case xylene resistance
and thus si~u~taneously good resistance to premium grade
gasoline is important; in addition, automobi~e repair
paints should exhibit gsod curing at room temperature,
and release of environmental pollutants should only be
~ow. These prerequisites are substantially fulfilled
here.
In the examples below, % in each case denotes X by weight
and P ;n each case denotes parts by weight.
.,
Exa-ples
A Preparation of the curing components (A) (M;chael
donor)
~'
` 1) 858.4 P of tr;ethyl methanetricarboxylate and 436.6 P
` 20 of 1,6-hexaned;ol were mixed and heated to 140C under
nitrogen. At this temperature, ethanol was firstly
, `A~ re~oved by d;st;llation under atmospheric pressure
followed by a mixture of ethanol and triethyl methane-
tricarboxylate in vacuo. A total of 362 g were dis-
tilled off. 933 g of a colorless, viscous liquid
having a mean molecular weight (Mw; polystyrene stan-
' dard) of 70,000 and an equivalent weight of 304 g/mol
;~ remained as the residue.
: ~
2) 806.5 9 of diethylmonomethyl methanetricarboxylate and
340.9 9 of 1,4-butanediol were reacted analogously to
Example 1). After removing 259 9 of volatile compo-
nents by distillation, 889 9 of a pale yellow viscous
~; liquid having a mean molecular weight of 20,000 and an
equ;valent weight of 427 g/mol remained.
"
3) 858 9 of triethyl methanetricarboxylate and 440 9 of
trimethylolpropane were reacted at 140C analogously
to Example 1). A total of 600 g of volatile components
.,
~` 1 328888
- 19 -
were removed by distillation. A colorless, viscous
Liquid having a mean molecuLar weight of 4,300 and an
- equivalent weight of 295 g/mol were obtained.
4) 404 9 of diethyL acylmalonate and 231 9 of 1,6-hexane-
dioL were reacted analogously to Example 1). After
101 9 of voltaile components had been removed by dis-
tilLation, 534 9 of a colorless, slightly viscous
Liquid having a mean molecular weight of 1,700 and an
equivaLent weight of 268 g/~ol remained.
5) 404 9 of diethyl acylmalonate and 80 9 of trimethylol-
propane were reacted analogously to Example 1). A
total of 158 9 of volatile components were removed by
distillat;on. 326 9 of a colorless, slightly viscous
- liquid having a mean molecular weight of 3,200 and an
equivalent weight of 209 g/mol remained as the residue.
6) 103.31 9 of methyl diacetoacetate and 26.84 9 of tri-
methylolpropane were reacted at 106C analogously to
Example 1). After 60.2 9 of volatile components had
been removed by distillation, 76.2 9 of a pale yellow,
~; viscous liquid having an equivalent weight of 235
remained.
.
7) 25.04 P of magnesium turnings, 25 ml of dry ethanol
and 1 ml of tetrachloromethane were introduced into a
Z liter four-necked flask equipped with stirrer, reflux
condenser and dropping funnel, and salt formation was
initiated by warming carefully. 160.17 P of diethyl
maLonate, dissolved in 80 ml of ethanol, were added drop-
wise at a rate such that the reaction did not become
too vigorous. During the reaction time, a total of
'~ 300 ml of dry diethyl ether was added in portions.
After all the malonate had been added drop~ise, the
reaction mixture was kept under reflux for 2 hours
, until the magnesium turnings had substantially dis-
solved. 127 P of 1,6-hexanediol bischloroformate,
dissolved in 100 ml of ether, were then added dropwise
` - 20 - l 328 8 88
over the course of 2 hours, and the mixture vas left
to stand overnight at room temperature. The batch was
hydrolysed using 60 ml of acet;c acid, dissolved in
; 300 ml of water, the organ;c phase was washed with
water until neutral and dried over sodium sulfete, the
` organic solvent was removed on a rotary evaporator,
and the cLear, oiLy residue was crystaLLized by rapid
cooLing and trituration. 97.3 P of diethyL 1,6-hexane-
dioLbismethanetricarboxyLate were obtained as a
crystalLine solid of melting point 42C. The acid
number was 230.
8) 287.2 P of diethyl n;tromalonate and 247.9 P of tri-
!~ methyloLpropane were mixed at room temperature under
nitrogen, and the mixture was sLowly heated to a maxi-
mum of 140C, whereupon ethanol began to distil off.
` After S hours, the volatile components were removed at
-~; a temperature of 140C in a water-pump vacuum, and a
-~ total of 37.4 9 of a viscous, yellow oil having an
equivalent weight of 441 9 were obtained; the mean
~; molecular ~eight was 1,646.
-- .
9) 360 P of diethyl maLonate and 50.25 P of trimethyLoL-
.:-
propane were mixed under nitrogen, the mixture was
heated to 160C, 39 P of ethanoL were removed by dis-
tiLlation over the course of 5 hours, aLl the volatile
components were subsequently removed at 120C in a
~ :;
water-pump vacuum, and 179 P of a colorless oil whose
mean molecular weight was 3,600 ~ere obtained. 100 P
of the reaction product obtained, dissolved in 40 P of
dry ethanol, were added dropwise over the course of 2
hours to 12.52 P of magnesium turnings, 12.5 ml of dry
- ethanol and 0.5 ml of tetrachloromethane, and the mix-
; ture was subsequently kept under reflux for a further
3 hours until the nagnesium turnings had substantially
dissolved. 52 9 of e~hyl chloroformate, dissolved in
150 ml of ether, were subsequently added dropwise over
the course of 2 hours, and the mixture ~as left to
react at room temperature for 2 days. After hydrolysis
1 328888
- 21 -
using water and acetic acid (5:1~ until the mixture
~as slightly acidic, the organic phase was separated
off and dried over Na2S04, and the volatile components
were removed in a water-pump vacuum. 202.5 9 of a
carboxethylated product having an equivalent weight of
708 9 ~ere obtained.
1û) 2,090.1 9 of triethyl methanecarboxylate, 709.7 9 of
1,4-butanediol and 45û.0 9 of a polycaprolactonediol
having a molecular weight of 400 g/mol were mixed, the
mixture was heated at 125-135C for 7 hours under
nitrogen. A total of 697.5 9 of ethanol were removed
~ by distillation. 2,552.3 9 of a colorless, viscous
`~ liquid having an equivalent weight of 300 g/mol and a
mean molecular weight ~Mw; polystyrene standard) of
8,300 g/mol remained as the residue.
. .,
11) 85.9 9 of triethyl methanetricarboxylate were heated
- at 135-140C for 2 hours under nitreogen together with
- 20 95.85 q of a polyether polyol (R Pluracol TP 440,
- BASF). During this time, a total of 19.34 9 of etha-
nol distilled off. 162.41 9 of a colorless, highly
viscous liquid having an equivalent weight of 446 g/mol
. _
~- and a mean molecular weight (Mw; polystyrene stan-
~` 25 dard) of 7,400 g/mol remained.
B Preparation of component (B) (Michael acceptor)
~`'
` ~ 1,000 P of a glycidyl group-containing acrylate resin,
prepared from styrene, gLycidyl methacrylate and dimethyl
~, maleate (epoxide equivalent ueight 510), were dissolved in
680 P of xylene at 70C, and 127 P of acryl;c acid and 1 P
, of tetraethylammonium bromide were subsequently added.
u~ ~hile passing air through the mixture, stirring ~as con-
tinued at 80C until the mixture had an acid number < 1.
The pale yellow solution had a solids content of 62.5Z;
C=C equivalent ~eight: 1,022.
:'
- 22 - ~ 1 3 2 8 8 8 8
C Preparation of the curable mixture/coatings
The amounts by weight of components (A) and (B) and of
- the catalyst which are given in the table below were
5 mixed. After a spread time of 2S seconds had bee~ set
using butyl acetate in accordance with 4 DIN 53211/23C,
the coating material obtained was applied to glass plates
.,.
, in a wet~film thickness of 100 ~m by means of an appli-
cation doctor blade and cured at 60C for 30 minutes.
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