(Meth) acrylated melamine formaldehyde resins

13 Pages·2013·1.82 MB·English

US008415437B2
(12) United States Patent (10) Patent N0.2 US 8,415,437 B2
Schwalm et a]. (45) Date of Patent: Apr. 9, 2013
(54) (METH)ACRYLATED MELAMINE 4,357,219 A * 11/1982 Sattler ........................... .. 522/92
FORMALDEHYDE RESINS 4,409,077 A * 10/1983 Sakiyama et a1. . 522/167
5,288,523 A * 2/1994 Klaiber et al. 427/385.5
. . _ 5,866,259 A * 2/1999 Harris et a1. 428/424.4
(75) Inventors: Reinhold SchWalm, Wachenhe1m (DE), 5,888,655 A * 3/1999 Harris et a1‘ 428/4231
Chrlstlne Roesch, Oppenhelm (DE) 6,777,458 B1* 8/2004 JaWorek et a1. ................. .. 522/1
7,164,037 B2 1/2007 Dietsche et a1.
(73) Assignee: BASF SE, LudWigshafen (DE) 7,517,474 B2 4/2009 Wagner et a1~
8,198,387 B2 * 6/2012 Kawada et a1. ............. .. 526/261
( * ) Notice: Subject to any disclaimer, the term of this l Z; 311'
patent is extended or adjusted under 35 '
U.S.C. 154(b) by 0 days. FOREIGN PATENT DOCUMENTS
DE 19618 720 11/1996
(21) Appl. No.: 13/131,995 DE 196 51350 6/1998
DE 199 57 900 6/2001
(22) PCT Filed: Aug. 2, 2010 EP 0 007 508 2/1980
EP 0 057 474 8/1982
. EP 0 263 749 4/1988
(86) PCT No.. PCT/EP2010/061169 EP 0495 751 7/1992
§ 371 (0X1) EP 0 615 980 9/1994
’_ EP 0 675 141 10/1995
(2), (4) Date- May 31’ 2011 EP 0 738 740 10/1996
EP 198 26 712 12/1999
(87) PCT Pub. No.: W02011/015539 EP 199 13 353 9/2()()()
JP 63 286426 ll/l988
PCT Pub. Date: Feb. 10, 2011 JP 2004122456 A * 4/2004
W0 98 33761 8/1998
(65) Prior Publication Data WO 2004 050888 6/2004
WC 2008 022922 2/2008
US 22, W0 2010 130608 11/2010
(30) Foreign Application Priority Data OTHER PUBLICATIONS
Aug. 5, 2009 (EP) ................................... .. 09167273 Giacobbe, T1» et 91» “Syntheses Of Monomers from Hydmxyethyl
Acrylate and Methylolmelamine Which PolymeriZe by Low Doses of
(51) Int_ CL Radiation,” Macromolecules, vol. 4, No. 5, pp. 630-632, (Sep.-Oct.
C08F 283/00 (2006.01) 1971)~ _ _ _
C08F 277/00 (200601) Internatlonal Search Report lssued Dec. 6, 2010 1n PCT/EP10/
C08F 271/02 (200601) 061169 ?led Aug. 2, 2010.
C08F 271/00 (2006.01) * . .
(52) U 5 Cl cited by examiner
USPC ......... .. 525/518; 525/509; 525/519; 522/134; _ _ 1 d
522/135; 522/136; 522/144; 522/149; 522/151; Pr’mry Examl’qer * Sam‘ MCC ‘in on _
522/162; 522/166; 522/167; 522/173; 522/178 (74) Alwmey] _ 486"’! 0? Flrm * 0121011, SPWak,
(58) Field of Classi?cation Search ................ .. 522/134, Mcclenand, Male/r & Neustad" L-L-P
522/135,136,144,149,151,162,166,167,
522/173, 178, 182; 525/50, 509, 518, 519 (57) ABSTRACT
See apphcanon ?le for Complete Search hlstory' The present invention relates to melamine-formaldehyde res
(56) References Cited ins bearing (meth)acrylic groups, to processes for preparing
them, to their use, and to coating compositions comprising
them.
U.S. PATENT DOCUMENTS
3,464,938 A * 9/1969 Nordstrom .................. .. 525/159
4,266,053 A 5/1981 Imanakaetal. 9 Claims, No Drawings
US 8,415,437 B2
1 2
(METH)ACRYLATED MELAMINE molar melamine:formaldehyde:alcohol incorporation ratio of
FORMALDEHYDE RESINS 1:3 to 5.4:2 to 4.3, is distinguished by a thermal reactivity
Which is signi?cantly increased in comparison to the ?rst
The present invention relates to melamine-formaldehyde group, Without acid catalysis. The production of these
resins bearing (meth)acrylic groups, to processes for prepar crosslinkers is accompanied by self-condensation, leading to
ing them, to their use, and to coating compositions compris a higher viscosity (loWer high-solids behavior) and making
ing them. the removal of the free formaldehyde during distillation more
Pigmented paints and transparent varnishes comprising or dif?cult as a result. For these products a free formaldehyde
based on melamine-formaldehyde resins have been knoWn content of 0.5% to 1.5% is standard, though there are also
for a number of decades. products having a free formaldehyde content of 0.3% to 3%
UnplasticiZed melamine-formaldehyde resins serve, either by Weight. Here again, methylated and butylated commercial
on their oWn or in combination With further, chemically dif products, and also grades With mixed etheri?cation, are Wide
ferent crosslinkers, examples being blocked polyisocyanates, spread. Etheri?cation With other alkylating compounds is
trisalkylcarbamoyltriaZines (TACT) or epoxides, as a described in the literature, and the corresponding products are
crosslinking component in binder mixtures. Curing of the available as specialty products.
?lm-forming constituents produces a coating Which is resis High-imino grades and methylol grades, each as a sub
tant to chemical, mechanical, and Weathering-induced in?u group, both feature incomplete methylolation, i.e., molar
ences. PlasticiZed melamine-formaldehyde resins may fea formaldehyde incorporation ratios of less than 1:5.5. The
ture modi?cations With carbamate structures, blends With high-imino grades differ from the methylol grades, hoWever,
polyesters or alkyd resins, and/ or precondensations With the 20 in a high degree of alkylation, i.e., in the proportion of the
latter. When used on ?exible coating substrates lacking etheri?ed methylol groups as a fraction of the incorporated
dimensional stability, unplasticiZed melamine-formaldehyde formaldehyde equivalents, Which is usually up to 80%,
resins require external elasti?cation in order for the coating Whereas for the methylol grades it is generally <70%.
not to tear; as a sole formulating constituent, the crosslinker Applications for the partly methylolated melamine-form
forms only brittle netWorks. 25 aldehyde resins extend across all ?elds of use, including
Melamine-formaldehyde resins can be characterized combinations With HMMM grades, for adaptation of reactiv
according to application (molding compounds, glues, ity, Where curing temperatures of 100 to 1500 C. are required.
impregnating resins, coating materials), alkylating com Additional catalysis using Weak acids is possible and is com
pounds (etheri?cation With butanol, methanol, mixed etheri mon practice.
?cation) or, as set out here, by the ratio of triaZine to formal 30 Besides the reaction of the amino resin With the binder
dehyde to etherifying alcohol: there is a substantially increased proportion of self-crosslink
1. fully to highly methylolated and fully alkylated to highly ing on the part of the crosslinker. The consequence is reduced
alkylated resins (HMMM grades) elasticity in the system as a Whole, and this reduction must be
2.1 partly methylolated and highly alkylated resins (high compensated by an appropriate selection of the co-compo
imino grades) 35 nent. Set against this is the advantage of reduced total form
2.2. partly methylolated and partly alkylated resins (methylol aldehyde emission from the coatings produced from the sys
grades)
tem.
3. resins With a loW degree of methylolation (melamine Finishes based on melamine-formaldehyde condensation
formaldehyde condensates) resins are used in the automotive segment, for industrial coat
The ?rst major group of the fully etheri?ed melamine 40 ings generally, but also for Wood and plastic. The coating
formaldehyde resins, in Which the molar melamine:formal systems feature particular hardness, gloss, resistance to
dehyde:alcohol incorporation ratio is theoretically 1:6:6, in chemicals and to yelloWing, and Weather resistance.
practice generally 1:>5.5:>5.0, and usually 1:>5.5:>4.0, is The reaction of melamine-formaldehyde resins With poly
distinguished by extremely good high-solids behavior (rela mers containing carbamate groups is knoWn, as from EP
tively loW viscosity at high solids content). In this group of 738740 or EP 675141, for example.
crosslinkers the free formaldehyde is readily reducible. At the The copolymers described therein are obtained by free
present time it is possible to achieve a free formaldehyde radical polymeriZation of acrylates and comonomers Which
content<0.3% by Weight. The commercial products usually comprise a carbamate group and a (meth)acrylic group and
comprise methanol as the alcohol, although grades With can then be reacted in conventional manner With amino res
mixed etheri?cation, and fully butylated grades, are also 50 ins, for example, to form crosslinked ?lm-forming resins.
knoWn. The preparation of comonomers of this kind Which bear a
The fully etheri?ed melamine-formaldehyde resins are carbamate group and a (meth)acrylic group is knoWn from
employed in practice preferably in can coating and coil coat WO 2004/050888 (corresponding to Us. Pat. No. 7,164,
ing and for all coats of the automobile ?nish. 037), for example.
The loW thermal reactivity under baking conditions, such 55 Their structural ?exibility makes melamine-formaldehyde
as 20 minutes at 1400 C., necessitates catalysis With strong resins interesting starting compounds for radiation-curable
acids for these fully etheri?ed melamine-formaldehyde res compounds.
ins. This results in very rapid curing, and a homogeneous Reaction products of etheri?ed melamines With hydroxyl
co-netWork as a result of transetheri?cation With the binder, acrylates are knoWn for application in radiation-curable coat
accompanied by the release of the etherifying alcohols. With 60 ing compositions; see, for example, T. J. Giacobbe et al.,
this strong-acid catalysis, very short cure times are possible, Macromolecules, 4, 1971, 630 ff. or JP63286426.
as in the case of partly methylolated melamine-formaldehyde The presence of acid-labile formals or N,O-acetals, hoW
resins. Crosslinking may be accompanied by formaldehyde ever, makes such structures unstable in the acidic pH range,
emission Which goes Well beyond the free formaldehyde and and this is manifested, for example, in lability under moisture
is due to the re-cleavage of methylol groups. 65 exposure (see beloW).
The second major group of the partly etheri?ed melamine U.S. Pat. No. 4,266,053 describes (meth)acrylates com
formaldehyde resins, Which in practice generally feature a prising melamine rings, prepared as reaction products of
US 8,415,437 B2
3 4
melamine-based polyols With (meth)acrylic acid, for use in incorporated by reference to become part of the present
UV-curing coatings oniamong othersiplastics parts. description, or in the German patent application With the
Although they feature better moisture resistance than the application number 1020090030352 and the ?ling date of
compounds described by T. J. Giacobbe et al. (see compara May 12, 2009 (corresponding to the international patent
tive example 1 in table 1 of Us. Pat. No. 4,266,053), their application With the application number PCT/EP2010/
preparation is necessarily complicated, on the basis of cya 056079 and the application date of May 5, 2010, and also to
the Us. patent application Ser. No. 12/ 776,670 and the appli
nuric chloride.
cation date of May 10, 2010).
It Was an object of the present invention to provide neW,
Following compounds of the formula (I) are preferred:
radiation-curable compounds based on melamine-formalde
Y is preferably 1,2-ethylene, 1,2-propylene, 1,3-propy
hyde resins that are stable to re-cleavage over a broad pH
lene, more preferably 1,2-ethylene and 1,2-propylene, and
range, and are simple to prepare.
very preferably 1,2-propylene.
This object has been achieved by means of radiation-cur
Examples of R3 and/or R4 are hydrogen, methyl, ethyl,
able compounds obtainable by reacting at least one
isopropyl, n-propyl, n-butyl, isobutyl, sec-butyl, tert-butyl,
melamine-formaldehyde resin With at least one compound of
n-hexyl, n-heptyl, n-octyl, n-decyl, n-dodecyl, n-tetradecyl,
the formula (I),
n-hexadecyl, n-octadecyl, n-eicosyl, 2-ethylhexyl, cyclopen
tyl, cyclohexyl, cyclooctyl, cyclododecyl, 2-hydroxyethyl,
2-hydroxypropyl, 1 -hydroxypropyl, 5 -hydroxy-3 -oxa-pen
O O
tyl, 8-hydroxy-3,6-dioxaoctyl or 1 1-hydroxy-3,6,9-trioxaun
R3\ III 1 O/ Y \O)KK decyl.
20
R3 and/or R4 is preferably hydrogen, methyl, ethyl, isopro
pyl, n-butyl, tent-butyl, and cyclohexyl, more preferably
hydrogen, methyl, ethyl, n-butyl, and tert-butyl, very prefer
ably hydrogen, methyl or ethyl, more particularly hydrogen
in Which
R3 and R4 independently of one another are hydrogen, 25 or methyl, and especially both radicals are hydrogen.
Preferably the alcohols (C) are selected from the group
Cl-Cl8 alkyl, C6-Cl2 aryl or C5-Cl2 cycloalkyl,
consisting of 2-hydroxyethyl carbamate, 2-hydroxy-1-propyl
Y is selected from 1,2-ethylene, 1,2-propylene, 1,1-dim
ethyl-1,2-ethylene, 1-hydroxymethyl-1,2-ethylene, 2-hy carbamate and 3-hydroxy-2-propyl carbamate. The latter are
droxy-1,3-propylene, 1,3-propylene, 1,4-butylene, 1,6-hexy used preferably in the form of an isomer mixture.
lene, 2-methyl-1,3-propylene, 2-ethyl-1,3-propylene, 2,2 30 A melamine-formaldehyde resin in the context of the
present speci?cation is the reaction product of melamine,
dimethyl-1,3-propylene, and 2,2-dimethyl-1,4-butylene, or
formaldehyde, and, if desired, at least one alcohol, preferably
of melamine, formaldehyde, and one or tWo alkanols, more
preferably melamine, formaldehyde, and an alkanol. With
35 very particular preference the alkanols are selected from the
group consisting of methanol, ethanol, n-butanol, isobutanol,
and secondary-butanol, preferably selected from the group
consisting of methanol, n-butanol, and isobutanol; more pref
or 1,2-, 1,3- or 1,4-cyclohexylene, erably they are methanol and/or n-butanol, and very prefer
R1 is hydrogen or methyl, preferably hydrogen, 40 ably methanol or n-butanol.
With the proviso that at least one of the radicals R3 and R4 The melamine-formaldehyde resin is preferably a com
is hydrogen. pound of the formula
The compounds of the formula (I) can be prepared prefer
ably by esterifying alcohols (C) containing urethane groups
45 in Which
Mel-N3 is a melamine radical formed by imaginary
(C) abstraction of the six hydrogen atoms attached to the amino
o groups in melamine,
R3 i Y H PA is a group 4CH24Oi,
\III 0/ \O/
50 R5 is a Cl-C8 alkyl group.
R5 in accordance With the invention is one or more different
R4
Cl-C8 alkyl groups, preferably a Cl-C4 alkyl group, prefer
ably a methyl, ethyl or butyl group, very preferably a methyl
With (meth)acrylic acid or With a (meth)acrylic ester, pref group or an n-butyl group, more particularly a methyl group.
erably a (meth)acrylic acid alkyl ester, more preferably a 55 Cl-C8 alkyl groups are for example methyl, ethyl, n-pro
(meth)acrylic acid alkyl ester Whose alkyl radical contains 1 pyl, isopropyl, n-butyl, isobutyl, 2-butyl, tert-butyl, 1-pentyl,
to 8 carbon atoms. 2-pentyl, isoamyl, n-hexyl, n-octyl or 2-ethylhexyl.
One possible preferred preparation of such alcohols (C) C 1 -C4 alkyl for the purposes of this speci?cation is methyl,
containing urethane groups is described in WO 2004/ 050888, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, 2-butyl or tert
page 3 line 26 to page 7 line 23 (corresponding to Us. Pat. 60 butyl.
No. 7,164,037, column 2 line 56 to column 5 line 33), Which Butanol for the purposes of this speci?cation refers collec
is hereby incorporated by reference to become part of the tively to n-butanol, isobutanol, sec-butanol, and mixtures
present description. thereof, preferably n-butanol or isobutanol, and more prefer
One possibility for the preparation of the compounds of the ably n-butanol.
formula (I) is described in WO 2004/050888, page 8 line 7 to 65 fA can adopt any desired values from 3.6 to a maximum of
page 11 line 38 (corresponding to Us. Pat. No. 7,164,037, 6.0. Preferably fA is at least 4.1, more preferably at least 4.2,
column 5 line 57 to column 8 line 34), Which is hereby and very preferably at least 5.0.
US 8,415,437 B2
5 6
Generally speaking, fA adopts values of preferably a maxi The free formaldehyde content is more particularly not
mum of 6.0, more preferably not more than 5.8, very prefer more than 0.2% and especially not more than 0.15% by
ably not more than 5.6, and more particularly not more than Weight, and in individual cases is not more than 0.1% by
5.4. Weight.
On the basis of a consideration of the fundamentals, mA The free formaldehyde content is determined in accor
cannot be greater than fA . dance With EN ISO 11402.
For example, mA adopts values of at least 2.0, preferably at Information on the resin distribution according to polymer
least 2.4, more preferably at least 2.9, and very preferably at de?nition is provided by gel permeation chromatography
least 3.4. (GPC) and by GPC/MS coupling. The resins may comprise
Generally speaking, mA is not greater than 5.0, preferably dimers and trimers and also higher oligomers, up to a mass
not greater than 4 .9, more preferably not greater than 4 .8, and fraction of 90%.
very preferably not greater than 4.7. The compounds of the invention are obtainable by a reac
The formula Mel-N3 FAfA RSMA H67“ is considered a tion of melamine-formaldehyde resins With (meth)acrylates
description in general form and is calculated from the resin bearing carbamate groups, Which proceeds preferably at
analyses Without taking account of any bridges formed by acidic pH:
condensation. Starting from total nitrogen, determined by The reaction takes place at a pH of not more than 6.0,
means of elemental analysis, the melamine content in the preferably not more than 5.0, more preferably not more than
resin structure is calculated and is standardized as Mel-N3:1. 4.5, very preferably betWeen 1 and 4, and more particularly
The incorporated formaldehyde is calculated as total formal 20 betWeen 1 and 3.
dehyde (determined folloWing acid digestion) minus the free Suitable acidic catalysts are sulfuric acid, nitric acid, phos
formaldehyde (DIN 16746-A, sul?te method), on a molar phoric acid, hydrochloric acid, para-toluenesulfonic acid,
basis based on melamine. This is the number fA . The incor benZenesulfonic acid, dodecylbenZenesulfonic acid, meth
porated alcohol is determined from the difference betWeen anesulfonic acid or mixtures thereof; acidic ion exchangers
the total alcohol content, according to gas chromatography 25 are also conceivable. Preference is given to sulfonic acids,
after acid digestion, and the free alcohol content according to particular preference to para-toluenesulfonic acid, benZene
gas chromatography, on a molar basis based on melamine. sulfonic acid, dodecylbenZenesulfonic acid, methanesulfonic
In one preferred embodiment of the present invention, in acid or mixtures thereof.
the melamine-formaldehyde resin employed, of the methylol The acidic catalyst Will be added generally in amounts of
groups that are present in the molecule, introduced by form 30 0.1% to 10%, preferably 0.5% to 7.5%, more preferably 1%
aldehyde, Whose number is given by fA , there are generally at to 6%, and very preferably 3% to 5%, by Weight. It may be
least 50% that are etheri?ed by groups R5, and so mA§0.5><fA, sensible to introduce the catalyst in tWo or more portions.
preferably at least 55%, more preferably at least 60%, and The molar stoichiometric ratio betWeen the compound of
more preferably at least 65%. the formula (I) and melamine-formaldehyde resin employed
35
Generally speaking, not more than 99% are etheri?ed by (based on melamine units in the melamine-formaldehyde
groups R5, and so mA§0.99><fA, preferably not more than resin) in the reaction is generally from 10:1 to 1:1, preferably
95%, more preferably not more than 90%, and very prefer from 8:1 to 1.5:1, more preferably from 6:1 to 2:1. If the
ably not more than 87%. intention is that some of the compound of the formula (I)
For the above-mentioned HMMM grades, hoWever, it is should not react during the reaction, it may remain unreacted
40
entirely possible for all methylol groups to be etherifed, and and Without separation in the reaction mixture, and may func
so for these resins it is the case that mAIfA. tion as a reactive diluent.
The solids content of the melamine-formaldehyde resin In accordance With the invention it is unimportant Whether
employed has no part to play in accordance With the inven the compound of the formula (I) is introduced ?rst and the
tion. The solids content may be, for example, at least 50%, 45 melamine-formaldehyde resin added, or the melamine-form
preferably at least 60%, more preferably at least 70%, and aldehyde resin is introduced ?rst in a part of the compound of
very preferably at least 75%, by Weight. the formula (I), and the remainder of the compound of the
In general the solids content Will not exceed 98%, and With formula (I) is added continuously or in portions, or the
preference Will not exceed 97%. melamine-formaldehyde resin is introduced ?rst and then the
The solids content is determined in accordance With ISO 50 compound of the formula (I) is added.
3251, by spreading out 2 g of the sample material and 2 ml of The temperature in the reaction ranges generally from
n-butanol in a Well-ventilated drying cabinet for a duration of room temperature to 1500 C., preferably from 50 to 1300 C.,
2 hours With heating at 125° C. For the calculation, the sample more preferably from 60 to 120° C., and very preferably from
is Weighed before and after, and the ratio provides the solids 70 to 100° C.
55
content. The reaction time during the transetheri?cation is from 10
The melamine-formaldehyde resin employed may com minutes to 6 hours.
prise at least one solvent, examples being Water, C l-C4 alkyl The number-average molar weight M” of the resultant,
alcohols, such as methanol, ethanol, isopropanol, n-propanol, inventively modi?ed melamine-formaldehyde resins is gen
n-butanol, isobutanol, sec-butanol or tert-butanol, for erally less than 2000 g/mol, preferably less than 1500 g/mol,
60
example, or aromatic hydrocarbons, such as toluene or else and more preferably less than 1300 (determined by gel per
xylene isomer mixtures, for example. meation chromatography With tetrahydrofuran and polysty
The free formaldehyde content of the melamine-formalde rene as standard, DIN 55672, Part 1).
hyde resin employed is generally not more than 1.5% by In one preferred embodiment the acid number of the result
Weight; for example, it may be not more than 1.0%, prefer 65 ant melamine-formaldehyde resins is less than 20, more pref
ably not more than 0.6%, more preferably not more than erably less than 15, and very preferably less than 10 mg
0.5%, and very preferably not more than 0.3%, by Weight. KOH/ g, determined in accordance With ISO 3682.
US 8,415,437 B2
7 8
In one preferred embodiment the color number of the (Cyclo)aliphatic hydrocarbons are for example decalin,
resultant melamine-formaldehyde resins is less than 200, alkylated decalin, and isomer mixtures of linear or branched
more preferably less than 1 50, determined in accordance With alkanes and/or cycloalkanes.
DIN EN 1557. Of further preference are n-butyl acetate, ethyl acetate,
The free formaldehyde content as per EN ISO 1 1402 in the 1-methoxyprop-2-yl acetate, 2-methoxyethyl acetate, and
resultant melamine-formaldehyde resins is generally not also mixtures thereof, especially With the aromatic hydrocar
bon mixtures set out above.
more than 0.5%, preferably not more than 0.3%, more pref
Mixtures of this kind may be produced in a volume ratio of
erably not more than 0.1%, and very preferably not more than
0.05% by Weight. 10:1 to 1:10, preferably in a volume ratio of 5:1 to 1:5, and
more preferably in a volume ratio of 1:1, not counting any
The modi?ed melamine-formaldehyde resin obtained in
solvents still present in the reaction mixture from the
accordance With the invention may subsequently be mixed
transetheri?cation, and more particularly the alcohols RSOH
With commonplace solvents.
and R6OH.
Examples of such solvents are aromatic and/or (cyclo)
Preferred examples are butyl acetate/xylene, 1:1 methox
aliphatic hydrocarbons and mixtures thereof, halogenated
ypropyl acetate/xylene, 1:1 butyl acetate/ solvent naphtha
hydrocarbons, esters, ethers, and alcohols. 100, 1:2 butyl acetate/Solvesso® 100, and 3:1 Kristalloel
Preference is given to aromatic hydrocarbons, (cyclo)ali
30/Shellsol® A.
phatic hydrocarbons, alkanoic acid alkyl esters, alkoxylated
Alcohols are for example methanol, ethanol, n-propanol,
alkanoic acid alkyl esters, and mixtures thereof. isopropanol, n-butanol, sec-butanol, isobutanol, pentanol iso
Particular preference is given to mono- or polyalkylated 20 mer mixtures, hexanol isomer mixtures, 2-ethylhexanol or
benZenes and naphthalenes, alkanoic acid alkyl esters and octanol.
alkoxylated alkanoic acid alkyl esters, and mixtures thereof. Also conceivable, though less preferred, is Water, espe
Preferred aromatic hydrocarbon mixtures are those com cially When used With other organic solvents as solubiliZers in
prising predominantly aromatic C7 to C14 hydrocarbons and a mixture.
being able to encompass a boiling range from 1 10 to 300° C.; 25 The amount of the resultant melamine-formaldehyde res
particular preference is given to toluene, o-, m- or p-xylene, ins in the solvents after mixing can be in general up to 98% by
trimethylbenZene isomers, tetramethylbenZene isomers, eth Weight, based on the sum of melamine-formaldehyde resin
ylbenZene, cumene, tetrahydronaphthalene, and mixtures and solvent, preferably up to 95%, more preferably up to
comprising them. 90%, very preferably up to 86%, and more particularly up to
80%, by Weight.
Examples thereof are the Solvesso® grades from Exxon 30
In one preferred embodiment of the present invention the
Mobil Chemical, especially Solvesso® 100 (CAS No. 64742
modi?ed melamine-formaldehyde resins obtainable in accor
95-6, predominantly C9 and C10 aromatics, boiling range
dance With the invention are prepared in a reactive diluent
about 154-178° C.), 150 (boiling range about 182-207° C.),
and/ or mixed With such diluents after their preparation.
and 200 (CAS No. 64742-94-5), and also the Shellsol®
35 Reactive diluents of this kind are at least one, for example
grades from Shell. Hydrocarbon mixtures of para?ins, cyclo
one to three, preferably one to tWo, and more preferably just
paraf?ns, and aromatics are also available commercially
one compound Which contains at least one, preferably at least
under the Kristalloel names (for example, Kristalloel 30, tWo, free-radically polymeriZable, preferably radiation-cur
boiling range about 158-198° C. or Kristalloel 60: CAS No. able groups, for example tWo to six, preferably tWo to four,
64742-82-1), White spirit (for example likeWise CAS No. 40 and more preferably tWo to three.
64742-82-1) or solvent naphtha (light: boiling range about The reactive diluents preferably have a loW viscosity of,
155-180° C., heavy: boiling range about 225-300° C.). The preferably, less than 15 000 mPas (at 25° C. in accordance
aromatics content of hydrocarbon mixtures of this type is With DIN EN ISO 3219/A.3).
generally more than 90%, preferably more than 95%, more The reactive diluents have an average molecular Weight of
preferably more than 98%, and very preferably more than up to 1000, preferably up to 750 g/mol. The compounds in
99%, by Weight. It may be sensible to use hydrocarbon mix question are preferably polyether (meth)acrylate or a (meth)
tures having a particularly reduced naphthalene content. acrylate of a diol, triol or tetraol, or a urethane di(meth)
The density at 20° C. to DIN 51757 of the hydrocarbons acrylate based on a diisocyanate.
can be less than 1 g/cm3, preferably less than 0.95 and more Particularly preferred reactive diluents have a boiling point
preferably less than 0.9 g/cm3 . 50 of more than 200° C. under atmospheric pressure.
The aliphatic hydrocarbons content is generally less than The reactive diluents may for example be reactive diluents
5%, preferably less than 2.5%, and more preferably less than of the kind described generally in P.K.T. Oldring (editor),
1%, by Weight. Chemistry & Technology of UV & EB Formulations for
Halogenated hydrocarbons are for example chlorobenZene Coatings, Inks & Paints, Vol. II, Chapter III: Reactive Dilu
and dichlorobenZene or its isomer mixtures. 55 ents for UV & EB Curable Formulations, Wiley and SITA
Esters are for example n-butyl acetate, ethyl acetate, Technology, London 1997.
1-methoxyprop-2-yl acetate, and 2-methoxyethyl acetate, Examples of reactive diluents With a free-radically poly
and also the monoacetyl and diacetyl esters of ethylene gly meriZable group are methyl acrylate and methyl methacry
col, diethylene glycol, triethylene glycol, propylene glycol, late.
dipropylene glycol or tripropylene glycol, such as, for Preferred reactive diluents are the diesters and polyesters
example, butylglycol acetate. Further examples are also car of (meth)acrylic acid With diols or polyols. Particularly pre
bonates, such as preferably 1,2-ethylene carbonate, 1,2-pro ferred are hexanediol diacrylate, hexanediol dimethacrylate,
pylene carbonate or 1,3-propylene carbonate. octanediol diacrylate, octanediol dimethacrylate, nonanediol
Ethers are for example tetrahydrofuran (THF), dioxane, diacrylate, nonanediol dimethacrylate, decanediol diacrylate,
and also the dimethyl, diethyl or di-n-butyl ethers of ethylene 65 decanediol dimethacrylate, pentaerythrityl tetraacrylate,
glycol, diethylene glycol, triethylene glycol, propylene gly dipentaerythrityl tetraacrylate, dipentaerythrityl triacrylate,
col, dipropylene glycol or tripropylene glycol. pentaerythrityl tetraacrylate, etc. Also preferred are the esters
US 8,415,437 B2
9 10
of alkoxylated polyols, With 0t,[3-ethylenically unsaturated The present invention further provides coating composi
monocarboxylic and/or dicarboxylic acids, such as, for tions Which comprise
example, the polyacrylates or polymethacrylates oftrimethy at least one radiation-curable compound according to the
lolpropane, glycerol or pentaerythritol With on average three present invention,
fold to 20-fold, preferably three fold to 15-fold, more prefer if desired, at least one reactive diluent,
ably three fold to nine fold alkoxylation, especially ethoxy if desired, at least one solvent,
lation, and also of diethylene glycol, triethylene glycol, dipro if desired, further, typical coatings additives, and
pylene glycol or tripropylene glycol. Suitability is also at least one photoinitiator.
Examples of further, typical coatings additives Which can
possessed by the esters of alicyclic diols, such as cyclohex
be used include antioxidants, stabiliZers, activators (acceler
anediol di(meth)acrylate and bis(hydroxymethyl)cyclohex
ants), ?llers, pigments, dyes, antistats, ?ame retardants,
ane di(meth)acrylate.
thickeners, thixotropic agents, surface-active agents, viscos
With particular preference the reactive diluent is selected
ity modi?ers, plasticiZers or chelating agents.
from the group consisting of ethylene glycol di(meth)acry
Suitable thickeners, in addition to free-radically (co)poly
late, diethyleneglycol di(meth)acrylate, triethylene glycol
meriZed (co)polymers, include customary organic and inor
di(meth)acrylate, butanediol di(meth)acrylate, hexanediol
ganic thickeners such as hydroxylmethylcellulose or bento
di(meth)acrylate, trimethylolpropane mono-, di- or tri (meth) nite.
acrylate, pentaerythrityl mono-, di-, tri- or tetra(meth)acry Examples of chelating agents Which can be used include
late, and 2,2-bis-4-(2-hydroxy-3-methacryloyloxy)phenyl ethylene diamine acetic acid and salts thereof, and also
propane. 20 [3-diketones.
A further embodiment of the present invention uses, as Suitable ?llers comprise silicates, examples being silicates
reactive diluents, reaction products, free from NCO groups, obtainable by hydrolysis of silicon tetrachloride, such as
of aliphatic or aromatic diisocyanates and (meth)acrylic Aerosil® from Degussa, siliceous earth, talc, aluminum sili
esters Which carry isocyanate-reactive groups, preferably OH cates, magnesium silicates, calcium carbonates, etc.
groups. Use may be made, for example, of reaction products 25 Suitable stabiliZers comprise typical UV absorbers such as
of aliphatic or aromatic diisocyanates and hydroxyethyl oxanilides, triaZines, and benZotriaZole (the latter available as
(meth)acrylate, hydroxypropyl (meth)acrylate or hydroxybu Tinuvin® grades from Ciba-SpeZialitatenchemie), and ben
tyl (meth)acrylate. Preferred diisocyanates are are 2,4'- and Zophenones. These can be used alone or together With suit
able free-radical scavengers, examples being sterically hin
4,4'-diphenylmethane diisocyanate (MDI), 2,4- or 2,6
tolylene diisocyanate (TDI), tetramethylene diisocyanate, 30 dered amines such as 2,2,6,6-tetramethylpiperidine, 2,6-di
tert-butylpiperidine or derivatives thereof, e.g., bis(2,2,6,6
hexamethylene diisocyanate, 2,4'- and 4,4'-methylenebis(cy
tetramethyl-4-piperidyl)sebacate. Stabilizers are used
clohexyl)diisocyanate, xylylene diisocyanate, tetrameth
typically in amounts of 0. 1 % to 5.0% by Weight, based on the
ylxylylene diisocyanate, dodecyl diisocyanate, lysine alkyl
solid components present in the formulation.
ester diisocyanate, Where alkyl is C1 to C10, 2,2,4- or 2,4,4
trimethyl-1,6-hexamethylene diisocyanate, 1,4-diisocyana 35 Pigments may likeWise be included. Pigments, according
to CD Rompp Chemie LexikoniVersion 1.0, Stuttgart/New
tocyclohexane, 1,3- or 1,4-bis(isocyanatomethyl)cyclohex
York: Georg Thieme Verlag 1995, With reference to DIN
ane, triisocyanatotoluene, isophorone diisocyanate (IPDI),
55943, are particulate “organic or inorganic, chromatic or
2-butyl-2-ethylpentamethylene diisocyanate, 2-isocyanato
achromatic colorants that are virtually insoluble in the appli
propylcyclohexyl isocyanate, 3(4)-isocyanatomethyl-1-me
40 cation medium”.
thylcyclohexyl isocyanate, 1,4-diisocyanato-4-methylpen
Virtually insoluble here means a solubility at 250 C. beloW
tane, or and 2- or 4-methylcyclohexane 1,3-diisocyanate 1 g/ 1000 g of application medium, preferably beloW 0.5,
(H-TDI), or mixtures of the aforementioned isocyanates. more preferably beloW 0.25, very preferably beloW 0.1, and
Particularly preferred are reaction products of aliphatic more particularly beloW 0.05 g/ 1000 g of application
diisocyanates, such as tetramethylene diisocyanate, hexam 45 medium.
ethylene diisocyanate, 2,4'- and 4,4'-methylenebis(cyclo Where a pigment is used, it is necessary to ensure either
hexyl)diisocyanate, xylylene diisocyanate, tetramethylxy that the curing is carried out With electron beams or that a
lylene diisocyanate, dodecyl diisocyanate, lysine alkyl ester photoinitiator is used Which can be activated by the irradiated
radiation in spite of the pigmentation; for example, by the
diisocyanate, Where alkyl is C1 to C10, 2,2,4- or 2,4,4-trim
ethyl-1,6-hexamethylene diisocyanate, 1,4-diisocyanatocy 50 photoinitiator having a signi?cant absorption in a Wavelength
range in Which the pigment is suf?ciently transparent for the
clohexane, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane,
irradiated radiation. One preferred embodiment of the present
isophorone diisocyanate (IPDI), 2-butyl-2-ethylpentameth
ylene diisocyanate, 2-isocyanatopropylcyclohexyl isocyan invention uses no pigment and uses the coating composition
in clearcoat materials.
ate, 3 (4)-isocyanatomethyl- 1 -methylcyclohexyl isocyanate,
55 Examples of pigments comprise any desired systems of
1,4-diisocyanato-4-methylpentane, or and 2- or 4-methylcy absorption pigments and/or effect pigments, preferably
clohexane 1,3-diisocyanate (H-TDI), and hydroxyethyl
absorption pigments. There are no restrictions Whatsoever on
(meth)acrylate, hydroxypropyl (meth)acrylate or hydroxybu
the number or selection of the pigment components. They
tyl (meth)acrylate. Especially preferred are reaction products
may be adapted as desired to the particular requirements, such
of hexamethylene diisocyanate, isophorone diisocyanate,
60 as, for example, to the desired perceived color.
2,2,4- or 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, Effect pigments are all pigments Which exhibit a platelet
and hydroxyethyl methacrylate, hydroxypropyl methacrylate shaped construction and impart speci?c decorative color
or hydroxybutyl methacrylate, and also, especially, the reac effects to a surface coating. The effect pigments comprise, for
tion product of 2,2,4- and/or 2,4,4-trimethyl-1,6-hexameth example, all of the effect-imparting pigments Which can be
ylene diisocyanate and tWo equivalents of hydroxyethyl 65 employed commonly in vehicle ?nishing and industrial coat
methacrylate, as knoWn under the trivial name urethane ing. Examples of effect pigments of these kinds are pure metal
dimethacrylate or UDMA. pigments, such as aluminum, iron or copper pigments; inter
US 8,415,437 B2
11 12
ference pigments, such as titanium dioxide-coated mica, iron Also suitable are nonyelloWing or loW-yelloWing photoini
oxide-coated mica, mixed oxide-coated mica (e. g., With tita tiators of the phenylglyoxalic ester type, as described in
nium dioxide and Fe2O3 or titanium dioxide and Cr2O3), DE-A 198 26 712, DE-A 199 13 353 or WO 98/33761.
metal oxide-coated aluminum, or liquid-crystal pigments. Typical mixtures comprise, for example, 2-hydroxy-2-me
The color-imparting absorption pigments are, for example, thyl-1-phenylpropan-2-one and 1-hydroxycyclohexyl phenyl
ketone, bis(2,6-dimethoxybenZoyl)-2,4,4-trimethyl-pen
customary organic or inorganic absorption pigments Which
tylphosphine oxide and 2-hydroxy-2-methyl-1-phenylpro
can be used in the coatings industry. Examples of organic
pan-1-one, benZophenone and l-hydroxycyclohexyl phenyl
absorption pigments are aZo pigments, phthalocyanine pig
ketone, bis(2,6-dimethoxybenZoyl)-2,4,4-trimethylpen
ments, quinacridone pigments, and pyrrolopyrrole pigments.
tylpho sphine oxide and 1-hydroxycyclohexyl phenyl ketone,
Examples of inorganic absorption pigments are iron oxide
2,4,6-trimethylbenZoyldiphenylphosphine oxide and 2-hy
pigments, titanium dioxide, and carbon black.
droxy-2-methyl-1 -phenylpropan- 1 -one, 2,4, 6-trimethylben
Where the coating compositions are cured not With elec
Zophenone and 4-methylbenZophenone or 2,4,6-trimethyl
tron beams but instead by means of UV radiation, there is benZophenone and 4-methylbenZophenone and 2,4,6
preferably at least one photoinitiator present Which is able to trimethylbenZoyldiphenylphosphine oxide.
initiate the polymerization of ethylenically unsaturated
Preferred among these photoinitiators are 2,4,6-trimethyl
double bonds. benZoyldiphenylphosphine oxide, ethyl 2,4,6-trimethylben
Photoinitiators may be, for example, photoinitiators Zoylphenylphosphinate, bis(2,4,6-trimethylbenZoyl)-phe
knoWn to the skilled Worker, examples being those speci?ed nylphosphine oxide, benZophenone, 1 -benZoylcyclohexan- 1 -
in “Advances in Polymer Science”, Volume 14, Springer Ber 20 ol, 2-hydroxy-2,2-dimethylacetophenone, and 2,2
lin 1974 or in K. K. Dietliker, Chemistry and Technology of dimethoxy-2-phenylacetophenone.
UV and EB Formulation for Coatings, Inks and Paints, Vol The coating compositions comprise the photoinitiators
ume 3; Photoinitiators for Free Radical and Cationic Poly preferably in an amount of 0.05% to 10% by Weight, more
meriZation, P. K. T. Oldring (editor), SITA Technology Ltd, preferably 0.1% to 8% by Weight, and more particularly 0.2%
London. 25 to 5% by Weight, based on the total amount of the curable
Suitability is possessed for example by monoacyl- or bisa components.
cylphosphine oxides, as described, for example, in EP-A 7 The coating materials can be employed in particular in
508, EP-A 57 474, DE-A 196 18 720, EP-A 495 751 or EP-A primers, surfacers, pigmented topcoat materials and clearcoat
615 980, examples being 2,4,6-trimethylbenZoyldiphe materials in the ?eld of automotive re?nish, large-vehicle
nylphosphine oxide (Lucirin® TPO from BASF SE), ethyl 30 ?nishing, and aircraft. Coating materials of this kind are
2,4,6-trimethylbenZoylphenylphosphinate (Lucirin® TPO L particularly suitable for applications requiring particularly
from BASF SE), bis(2,4,6-trimethylbenzoyl)phenylphos high levels of application reliability, external Weathering
phine oxide (lrgacure® 819 from Ciba SpeZialitatenchemie), resistance, hardness, and ?exibility, such as in automotive
benZophenones, hydroxyacetophenones, phenylglyoxylic re?nish and large-vehicle ?nishing.
acid and its derivatives, or mixtures of these photoinitiators. 35 Coating compositions, comprising the by the inventively
Examples include benZophenone, acetophenone, acetonaph obtainable mixtures are especially employed as or in automo
thoquinone, methyl ethyl ketone, valerophenone, hexanophe tive clearcoat and topcoat material(s). Further preferred ?elds
none, ot-phenylbutyrophenone, p-morpholinopropiophe of use are can coating and coil coating.
none, dibenZosuberone, 4-morpholinobenZophenone, Coil coating is the continuous coating of metal strips With
4-morpholinodeoxybenZoin, p-diacetylbenZene, 4-ami coating materials, usually liquid coating materials. Rolled
40
nobenZophenone, 4'-methoxyacetophenone, [3-methylan metal strips, after production, are Wound up into rolls (re
thraquinone, tert-butylanthraquinone, anthraquinonecar ferred to as “coils”) for the purposes of storage and transport.
boxylic esters, benZaldehyde, ot-tetralone, These metal strips represent the starting material for the
9-acetylphenanthrene, 2-acetylphenanthrene, 10-thioxan majority of sheetlike metallic Workpieces, examples being
thenone, 3-acetylphenanthrene, 3-acetylindole, 9-?uo 45 automobile parts, bodyWork parts, instrument paneling, exte
renone, 1-indanone, 1,3,4-triacetylbenZene, thioxanthen-9 rior architectural paneling, ceiling paneling or WindoW pro
one, xanthen-9-one, 2,4-dimethylthioxanthone, 2,4 ?les, for example. For this purpose the appropriate metal
diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4 sheets are shaped by means of appropriate techniques such as
dichlorothioxanthone, benZoin, benZoin isobutyl ether, punching, drilling, folding, pro?ling and/or deep draWing.
chloroxanthenone, benZoin tetrahydropyranyl ether, benZoin 50 Larger components, such as automobile bodyWork parts, for
methyl ether, benZoin ethyl ether, benZoin butyl ether, ben example, are assembled optionally by Welding together a
Zoin isopropyl ether, 7H-benZoin methyl ether, benZ[de]an number of individual parts.
thracen-7-one, 1-naphthaldehyde, 4,4'-bis(dimethylamino) For the coating operation, metal strips With a thickness of
benZophenone, 4-phenylbenZophenone, 4-chloro 0.2 to 2 mm and a Width of up to 2 m are transported at a speed
benZophenone, Michler’s ketone, l-acetonaphthone, 55 of up to 200 m/min through a coil coating line, and are coated
2-acetonaphthone, 1 -benZoyl-cyclohexan-1-ol, 2-hydroxy-2, in the process. For this purpose it is possible to use, for
2-dimethylacetophenone, 2,2-dimethoxy-2-phenylacetophe example, cold-rolled strips of soft steels or construction
none, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichlorac grade steels, electrolytically galvanized thin sheet, hot-dip
etophenone, 1 -hydroxy-ac etophenone, ac etophenone galvaniZed steel strip, or strips of aluminum or aluminum
dimethyl ketal, o-methoxybenZophenone, triphenylphos 60 alloys. Typical lines comprise a feed station, a coil store, a
phine, tri-o-tolylphosphine, benZ[a]anthracene-7,12-dione, cleaning and pretreatment Zone, a ?rst coating station along
2,2-diethoxyacetophenone, benZil ketals, such as benZil dim With baking oven and doWnstream cooling Zone, a second
ethyl ketal, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholi coating station With oven, laminating station, and cooling,
nopropan- 1 -one, anthraquinones such as 2-methylan and also a coil store and Winder.
thraquinone, 2-ethylanthraquinone, 2-tert 65 Characteristic of coil coatings are thin ?lms of the coating
butylanthraquinone, 1 -chloroanthraquinone, compositions, With a dry ?lm thickness of usually Well beloW
2-amylanthraquinone, and 2,3-butanedione. 80 um, often beloW 60 um, beloW 50 um, and even beloW 40
US 8,415,437 B2
13 14
um. Furthermore, the metal sheets are processed With a high The method of coating substrates can also be practiced by
throughput, Which necessitates short residence times, i.e., irradiating the applied coating composition of the invention,
necessitates drying at an elevated temperature following or paint formulations, ?rst With electron beams or UV expo
application of the coating, in order that the coating composi sure, under oxygen or, preferably, under inert gas, in order to
tion soon acquires load-bearing qualities. obtain preliminary curing, then carrying out thermal treat
Coating of the substrates With the coating compositions ment at temperatures up to 1600 C., preferably betWeen 60
takes place in accordance With typical processes knoWn to the and 1600 C., and subsequently completely curing With elec
skilled Worker, a coating composition or a paint formulation tron beams or UV exposure under oxygen or, preferably,
comprising it being applied in the desired thickness to the under inert gas.
target substrate and, optionally, dried. This operation may if Optionally, if a plurality of layers of the coating material
desired be repeated one or more times. Application to the are applied one on top of another, drying and/or radiation
substrate may take place in a knoWn Way, as for example by curing may take place after each coating operation.
spraying, troWeling, knifecoating, brushing, rolling, roller Examples of suitable radiation sources for the radiation
coating, pouring, laminating, injection backmolding or coex cure are loW-pressure, medium-pressure, and high-pressure
truding. mercury lamps, and also ?uorescent tubes, pulsed lamps,
Further disclosed is a method of coating substrates Which metal halide lamps, electronic ?ash devices, Which alloW
involves applying to the substrate a coating composition or a radiation curing Without a photoinitiator, or excimer lamps.
paint formulation comprising it, admixed optionally With fur The radiation cure is accomplished by exposure to high
ther, typical coatings additives and thermally, chemically or energy radiation, i.e., UV radiation or daylight, preferably
radiation-curable resins, drying the applied coating option 20 light emitted in the Wavelength range of 7t:200 to 700 nm,
ally, curing it With electron beams or UV exposure under an more preferably 7t:200 to 500 nm, and very preferably 7t:250
oxygen-containing atmosphere or, preferably, under inert to 400 nm, or by irradiation With high-energy electrons (elec
gas, and subjecting it to thermal treatment, optionally, at tron radiation; 150 to 300 keV). Examples of radiation
temperatures up to the level of the drying temperature, and sources used include high-pressure mercury vapor lamps,
thereafter at temperatures up to 160° C., preferably betWeen 25 lasers, pulsed lamps (?ash light), halogen lamps or excimer
60 and 1600 C., more preferably betWeen 100 and 1600 C. lamps. The radiation dose typically su?icient for crosslinking
Radiation curing takes place With high-energy light, UV in the case of UV curing is situated in the range from 80 to
light for example, or electron beams. Radiation curing may 3000 mJ/cm2.
take place at relatively high temperatures. Preference is given It Will be appreciated that it is also possible to use tWo or
in that case to a temperature above the T8 of the radiation 30 more radiation sources for the cure, tWo to four for example.
curable binder. These sources may also each emit in different Wavelength
Radiation curing here means the free-radical polymeriza ranges.
tion of polymeriZable compounds as a result of electromag Drying and/or thermal treatment may also take place, in
netic and/or particulate radiation, preferably UV light in the addition to or instead of the thermal treatment, by means of
Wavelength range of 7t:200 to 700 nm and/ or electron radia 35 NIR radiation, Which here refers to electromagnetic radiation
tion in the range from 150 to 300 keV, and more preferably in the Wavelength range from 760 nm to 2.5 um, preferably
With a radiation dose of at least 80, preferably 80 to 3000 from 900 to 1500 nm.
mJ/cm2. Irradiation can if desired also be carried out in the absence
Besides radiation curing there may also be further curing of oxygen, such as under an inert gas atmosphere. Suitable
mechanisms involved, examples being thermal curing, mois 40 inert gases are preferably nitrogen, noble gases, carbon diox
ture curing, chemical curing and/ or oxidative curing, prefer ide, or combustion gases. Furthermore, irradiation may take
ably thermal and radiation curing, and more preferably radia place With the coating composition being covered With trans
tion curing alone. parent media. Examples of transparent media are polymeric
The coating materials may be applied one or more times by ?lms, glass or liquids, Water for example. Particular prefer
any of a very Wide variety of spraying methods, such as 45 ence is given to irradiation in the manner described in DE-Al
compressed-air, airless or electrostatic spraying methods, 199 57 900.
using one- or tWo-component spraying units, or else by inject Suitable substrates for the coating compositions of the
ing, troWeling, knifecoating, brushing, rolling, roller coating, invention are, for example, thermoplastic polymers, more
pouring, laminating, injection backmolding or coextruding. particularly polymethyl methacrylates, polybutyl methacry
The coating thickness is generally in a range from about 3 50 lates, polyethylene terephthalates, polybutylene terephtha
to 1000 g/m2 and preferably 10 to 200 g/m2. lates, polyvinylidene ?uorides, polyvinyl chlorides, polyes
Drying and curing of the coatings take place generally ters, polyole?ns, acrylonitrile-ethylene-propylene-diene
under standard temperature conditions, i.e., Without the coat styrene copolymers (A-EPDM), polyetherimides,
ing being heated. Alternatively the mixtures of the invention polyetherketones, polyphenylene sul?des, polyphenylene
can be used to produce coatings Which, folloWing application, 55 ethers or mixtures thereof.
are dried and cured at an elevated temperature, e.g., at Mention may additionally be made of polyethylene,
40-250o C., preferably 40-150o C., and more particularly at polypropylene, polystyrene, polybutadiene, polyesters,
40 to 1000 C. This is limited by the thermal stability of the polyamides, polyethers, polycarbonate, polyvinyl acetal,
substrate. polyacrylonitrile, polyacetal, polyvinyl alcohol, polyvinyl
Additionally disclosed is a method of coating substrates 60 acetate, phenolic resins, urea resins, melamine resins, alkyd
Which involves applying the coating composition of the resins, epoxy resins or polyurethanes, their block copolymers
invention or paint formulations comprising it, optionally or graft copolymers, and blends thereof.
admixed With thermally curable resins, to the substrate, dry Mention may be made With preference of ABS, AES,
ing it, and then curing it With electron beams or UV exposure AMMA,ASA, EP, EPS, EVA, EVAL, HDPE, LDPE, MABS,
under an oxygen-containing atmosphere or, preferably, under 65 MBS, MF, PA, PA6, PA66, PAN, PB, PBT, PBTP, PC, PE,
inert gas, optionally at temperatures up to the level of the PEC, PEEK, PEI, PEK, PEP, PES, PET, PETP, PF, PI, FIB,
drying temperature. PMMA, POM, PP, PPS, PS, PSU, PUR, PVAC, PVAL, PVC,
US 8,415,437 B2
15 1 6
PVDC, PVP, SAN, SB, SMS, UF, UP plastics (abbreviations nonvolatiles content (as per ISO 3251) of 93-96% by Weight,
according to DIN 7728), and aliphatic polyketones. With a loW free formaldehyde content of not more than 0.3%
Particularly preferred substrates are polyole?ns, such as, by Weight. The viscosity (ISO 3219 B) is 2.0-6.0 Pas at 23° C.
for example, PP (polypropylene), Which may be alternatively and a shear rate D of41.3 s_l.
isotactic, syndiotactic or atactic and alternatively unoriented HPC acrylate is the formal reaction product of 2-hydrox
or oriented by monoaxial or biaxial stretching, SAN (styrene ypropyl carbamate (isomer mixture of 2-hydroxy-1-propyl
acrylonitrile copolymers), PC (polycarbonates), PVC (poly carbamate and 3-hydroxy-2-propyl carbamate) With acrylic
vinyl chlorides), PMMA (polymethyl methacrylates), PBT acid. The purity of the HPC acrylate Was at least 90% by
(poly(butylene terephthalate)s), PA (polyamides), ASA Weight, the amount of unacrylated 2-hydroxypropyl carbam
(acrylonitrile-styrene-acrylic ester copolymers) and ABS ate being beloW 5% by Weight, and the remainder being
(acrylonitrile-butadiene-styrene copolymers), and also their unreacted acrylates.
physical mixtures (blends). Particular preference is given to Erichsen cupping and scratch resistance.
PP, SAN, ABS, ASA, and also blends of ABS orASA With PA The pendulum damping Was determined in accordance
or PBT or PC. Very particular preference is given to polyole With DIN 53157. The pendulum damping is a measure of the
?ns, PMMA, and PVC. hardness of the coating. High values in this test denote high
Especially preferred is ASA, more particularly in accor hardness.
dance With DE 196 51 350, and the ASA/PC blend. Prefer The Erichsen cupping Was determined in accordance With
ence is likeWise given to polymethyl methacrylate (PMMA) DIN 53156. The Erichsen cupping is a measure of the ?ex
or impact-modi?ed PMMA. ibility and elasticity. It is reported in millimeters (mm). High
A further-preferred substrate for coating With the coating 20 values denote high ?exibility.
compositions of the invention are metals, Which if desired The residual gloss Was determined using the Scotch-Brite
may have been pretreated With a primer. test after storage for 7 days in a controlled-climate chamber.
The nature of the metal is in principle arbitrary. More In the Scotch-Brite test, a ?ber Web modi?ed With silicon
particularly, hoWever, the metal comprises those metals or carbide and measuring 3><3 cm (Scotch Brite SUFN, from
alloys Which are commonly used as metallic materials of 25 3M) is a?ixed as the test element to a cylinder. The cylinder
construction, and Which require protection from corrosion. presses the ?ber Web against the coating With a de?ned
The surfaces in question are more particularly those of applied Weight, and is moved over the coating pneumatically.
iron, steel, Zn, Zn alloys, Al or Al alloys. These may be the The path length of the de?ection is 7 cm.After 10 or 50 double
surfaces of bodies consisting Wholly of said metals/alloys. rubs (DR), the gloss is measured in the middle region of the
HoWever, it is also possible for the bodies to be only coated 30 exposure (eight-fold determination) in a method based on
With these metals and for the bodies themselves to be com DIN 67530 With an incidence angle of 20°. The residual gloss
posed of different kinds of materials, as for example of other value in percent is given by the ratio of gloss after expo sure to
metals, alloys, polymers or composites. The surfaces in ques initial gloss. High residual gloss values, i.e., loW values for the
tion may be surfaces of castings of galvaniZed iron or steel. In loss of gloss, denote high scratch resistance.
one preferred embodiment of the present invention the sur 35
faces are steel surfaces. Example 1
Zn alloys or Al alloys are knoWn to the skilled Worker. The
skilled Worker selects the nature and amount of alloying Preparation of Melamine Carbamate Hydroxypropyl
constituents in accordance With the desired application. Typi Acrylate in Bulk, Atmospheric Pressure
cal constituents of Zinc alloys comprise, in particular, Al, Pb, 40 The thoroughly mixed initial charge of 65.1 g of LuWipal
Si, Mg, Sn, Cu or Cd. Typical constituents of aluminum alloys 66, 173.17 g of HPC acrylate and 0.1732 g of methylhydro
comprise, in particular, Mg, Mn, Si, Zn, Cr, Zr, Cu or Ti. The quinone is admixed at room temperature With 1 .19 g of meth
alloys may also be Al/Zn alloys, in Which Al and Zn are anesulfonic acid. This system is heated to an external tem
present in approximately equal amounts. Steel coated With perature of 90° C., While air is bubbled through it. At an
alloys of this kind is available commercially. The steel may 45 internal temperature of 85° C., methanol distillation is com
comprise the customary alloying components knoWn to the menced. After the end of reaction, a product of high viscosity
skilled Worker. With a double bond density of 4.11 mol/kg is obtained.
Also conceivable is the use of the coating compositions of
the invention for the treatment of tin-plated iron/steel (tin Example 2
plate). 50
The coating compositions and paint formulations of the In Bulk, Reduced Pressure
invention are additionally suitable for coating substrates such The thoroughly mixed initial charge of 65.1 g of LuWipal
as Wood, paper, textile, leather, nonWoven, plastics surfaces, 66, 173.17 g of HPC acrylate and 0.1732 g of methylhydro
glass, ceramic, mineral construction materials, such as quinone is admixed at room temperature With 1 .19 g of meth
cement moldings and ?ber-cement slabs, or coated or 55 anesulfonic acid and 0.012 g of phenothiaZine. Heating takes
uncoated metals, preferably plastics or metals, more particu place at a pressure of about 300 mbar up to an external
larly in the form of ?lms or foils, With particular preference temperature of 90° C. At an internal temperature of 65° C.,
metals. methanol distillation commences. After the end of reaction, a
The examples Which folloW are intended to illustrate the highly viscous product having a double bond density of 4.08
properties of the invention, but Without restricting it. 60 mol/kg is obtained.
EXAMPLES Example 3
Unless indicated otherWise, “parts” in this speci?cation are Dilution With HDDA
to be understood as “parts by Weight”. 65 The thoroughly mixed initial charge of 52.1 g of LuWipal
LuWipal® 066LF from BASF SE is a highly to fully 66, 138.5 g of HPC acrylate and 0.01 g of phenothiaZine is
methyl-etheri?ed melamine-formaldehyde resin having a admixed at room temperature With 1.9 g of methanesulfonic
US 8,415,437 B2
17 1 8
acid. Under a pressure of about 300 mbar, heating takes place 21)
to an external temperature of 90° C. At an internal tempera using a four-path frame-type Wet ?lm applicator With a gap
ture of 690 C., methanol distillation commences. After the end depth of 300 um, Was applied to a glass substrate. After the
of reaction, the batch is diluted to a solids content of 80% by solvent had been ?ashed (1 5 minutes at room temperature, 20
addition of 47.7 g of hexanediol diacrylate. minutes at 800 C.), the ?lm Was exposed With 1900 mJ/cm2
(high-pressure Hg lamp) at room temperature in a nitrogen
Example 4 atmosphere. Cured ?lm:
Pendulum damping: 178 sec
Residual gloss after 10DR With 250 g applied Weight:
Dilution With BuAc
83.2%
The thoroughly mixed initial charge of 52.1 g of LuWipal
Residual gloss after 50DR With 250 g applied Weight:
66, 138.5 g of HPC acrylate and 0.01 g of phenothiaZine is
70.0%
admixed at room temperature With 1.9 g of methanesulfonic
b)
acid. Under a pressure of about 300 mbar, heating takes place
using a four-path frame-type Wet ?lm applicator With a gap
to an external temperature of 900 C. At an internal tempera depth of 400 um, Was applied to a glass substrate. After the
ture of 690 C., methanol distillation commences. After the end solvent had been ?ashed (1 5 minutes at room temperature, 20
of reaction, the batch is diluted to a solids content of 80% by minutes at 800 C.), the ?lm Was exposed With 1900 mJ/cm2
addition of 47.7 g of butyl acetate. (hi gh-pres sure Hg lamp) at room temperature in an air atmo
Use in UV-Curable Coatings sphere. Cured ?lm:
A formulation of 75% by Weight of melamine carbamate Pendulum damping: 135 sec
hydroxypropyl acrylate from example 1, 25% by Weight of 20 Residual gloss after 10DR With 250 g applied Weight:
butyl acetate and 4% of lrgacure® 184 (Ciba SpeZialita 54.3%
tenchemie, l-hydroxycyclohexyl phenyl ketone) Was pre Residual gloss after 50DR With 250 g applied Weight:
pared and 74.0%
21) C)
using a four-path frame-type Wet ?lm applicator With a gap 25 using a four-path frame-type Wet ?lm applicator With a gap
depth of 300 um, Was applied to a glass substrate. After the depth of 150 um, Was applied to a Bonder panel. After the
solvent had been ?ashed (15 minutes at room temperature, 20 solvent had been ?ashed (1 5 minutes at room temperature, 20
minutes at 800 C.), the ?lm Was exposed With 1900 mJ/cm2 minutes at 800 C.), the ?lm Was exposed With 1900 mJ/cm2
(high-pressure Hg lamp) at room temperature in a nitrogen (high-pressure Hg lamp) at room temperature in a nitrogen
atmosphere. Cured ?lm: 30 atmosphere. Cured ?lm:
Pendulum damping: 189 sec Erichsen cupping: 1.4 mm
Residual gloss after 10DR With 250 g applied Weight: (11)
90.9% using a four-path frame-type Wet ?lm applicator With a gap
Residual gloss after 50DR With 250 g applied Weight: depth of 200 um, Was applied to a Bonder panel. After the
82.6% 35 solvent had been ?ashed (1 5 minutes at room temperature, 20
b) minutes at 800 C.), the ?lm Was exposed With 1900 mJ/cm2
using a four-path frame-type Wet ?lm applicator With a gap (hi gh-pres sure Hg lamp) at room temperature in an air atmo
depth of 400 um, Was applied to a glass substrate. After the sphere. Cured ?lm:
solvent had been ?ashed (15 minutes at room temperature, 20 Erichsen cupping: 0.9 mm
minutes at 800 C.), the ?lm Was exposed With 1900 mJ/cm2 A formulation of 70% by Weight of melamine carbamate
(hi gh-pres sure Hg lamp) at room temperature in an air atmo hydroxypropyl acrylate (prepared according to example 1),
sphere. Cured ?lm: 30% by Weight of hexanediol diacrylate and 4% of lrgacure®
Pendulum damping: 138 sec 184 Was prepared and
Residual gloss after 10DR With 250 g applied Weight: 21)
62.3% 45 using a four-path frame-type Wet ?lm applicator With a gap
Residual gloss after 50DR With 250 g applied Weight: depth of 300 um, Was applied to a glass substrate. After the
60.8% solvent had been ?ashed (1 5 minutes at room temperature, 20
C) minutes at 800 C.), the ?lm Was exposed With 1900 mJ/cm2
using a four-path frame-type Wet ?lm applicator With a gap (high-pressure Hg lamp) at room temperature in a nitrogen
depth of 150 um, Was applied to a Bonder panel. After the atmosphere. Cured ?lm:
solvent had been ?ashed (15 minutes at room temperature, 20 Pendulum damping: 174 sec
minutes at 800 C.), the ?lm Was exposed With 1900 mJ/cm2 Residual gloss after 10DR With 250 g applied Weight:
(high-pressure Hg lamp) at room temperature in a nitrogen 93.8%
atmosphere. Cured ?lm: Residual gloss after 50DR With 250 g applied Weight:
Erichsen cupping: 1.1 mm 55 89.6%
d) b)
using a four-path frame-type Wet ?lm applicator With a gap using a four-path frame-type Wet ?lm applicator With a gap
depth of 200 um, Was applied to a Bonder panel. After the depth of 400 um, Was applied to a glass substrate. After the
solvent had been ?ashed (15 minutes at room temperature, 20 solvent had been ?ashed (1 5 minutes at room temperature, 20
minutes at 800 C.), the ?lm Was exposed With 1900 mJ/cm2 minutes at 800 C.), the ?lm Was exposed With 1900 mJ/cm2
(hi gh-pres sure Hg lamp) at room temperature in an air atmo (hi gh-pres sure Hg lamp) at room temperature in an air atmo
sphere. Cured ?lm: sphere. Cured ?lm:
Erichsen cupping: 0.9 mm Pendulum damping: 191 sec
A formulation of 80% by Weight of melamine carbamate Residual gloss after 10DR With 250 g applied Weight:
hydroxypropyl acrylate (prepared according to example 2), 68.3%
20% by Weight of butyl acetate and 4% of lrgacure® 184 Was Residual gloss after 50DR With 250 g applied Weight:
prepared and 32.8%