U.S. patent application number 14/246229 was filed with the patent office on 2014-08-07 for crosslinkable composition cross-linkable by real michael addition reaction and resins for use in said composition.
This patent application is currently assigned to NUPLEX RESINS B.V.. The applicant listed for this patent is NUPLEX RESINS B.V.. Invention is credited to Richard Hendrikus Gerrit BRINKHUIS, Antonius Johannes Wilhelmus BUSER, Elwin Aloysius Cornelius Adrianus DE WOLF, Petrus Johannes Maria David ELFRINK, Nicole MANGNUS-VERHAGEN, Ferry Ludovicus THYS.
Application Number | 20140221542 14/246229 |
Document ID | / |
Family ID | 47002872 |
Filed Date | 2014-08-07 |
United States Patent
Application |
20140221542 |
Kind Code |
A1 |
BRINKHUIS; Richard Hendrikus Gerrit
; et al. |
August 7, 2014 |
CROSSLINKABLE COMPOSITION CROSS-LINKABLE BY REAL MICHAEL ADDITION
REACTION AND RESINS FOR USE IN SAID COMPOSITION
Abstract
An RMA crosslinkable composition having at least one
crosslinkable component including reactive components A and B each
including at least 2 reactive groups, the at least 2 reactive
groups of component A being acidic protons (C--H) in activated
methylene or methine groups and the at least 2 reactive groups of
component B are activated unsaturated groups (C.dbd.C) and a base
catalyst (C) which reactive components A and B crosslink by Real
Michael Addition (RMA) reaction under action of the base catalyst,
characterised in that the at least one crosslinkable component
including reactive components A and B in the composition have a
total hydroxy number of less than 60, preferably less than 40 and
more preferably less than 20 mg KOH/g solids. Further, specific
resins A and B having a low hydroxy number for use in RMA
cross-linkable compositions and a process for the manufacture
thereof.
Inventors: |
BRINKHUIS; Richard Hendrikus
Gerrit; (ZWOLLE, NL) ; BUSER; Antonius Johannes
Wilhelmus; (WEHL, NL) ; ELFRINK; Petrus Johannes
Maria David; (Boxmeer, NL) ; THYS; Ferry
Ludovicus; (STEVENS-WOLUWE, BE) ; MANGNUS-VERHAGEN;
Nicole; (VOGELWAARDE, NL) ; DE WOLF; Elwin Aloysius
Cornelius Adrianus; (HOOGERHEIDE, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NUPLEX RESINS B.V. |
BERGEN OP ZOOM |
|
NL |
|
|
Assignee: |
NUPLEX RESINS B.V.
BERGEN OP ZOOM
NL
|
Family ID: |
47002872 |
Appl. No.: |
14/246229 |
Filed: |
April 7, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2012/069904 |
Oct 8, 2012 |
|
|
|
14246229 |
|
|
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|
Current U.S.
Class: |
524/389 ;
524/604; 528/308 |
Current CPC
Class: |
B01J 31/0268 20130101;
C08J 2367/00 20130101; C09D 133/14 20130101; C08J 3/24 20130101;
B01J 31/0205 20130101; C09D 167/00 20130101; C09D 175/06 20130101;
C08K 5/0008 20130101; C08J 2369/00 20130101; C08K 3/01 20180101;
C08G 63/12 20130101; C08K 5/21 20130101; C08J 2375/04 20130101;
B01J 2231/341 20130101; B01J 31/0239 20130101 |
Class at
Publication: |
524/389 ;
524/604; 528/308 |
International
Class: |
C09D 167/00 20060101
C09D167/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 7, 2011 |
EP |
11184439.5 |
Claims
1) An RMA crosslinkable composition comprising at least one
crosslinkable component comprising reactive components A and B each
comprising at least 2 reactive groups, wherein the at least 2
reactive groups of component A are C--H acidic protons in activated
methylene or methine groups, and the at least 2 reactive groups of
component B are C.dbd.C activated unsaturated groups and a base
catalyst C, which reactive components A and B crosslink by Real
Michael Addition reaction under action of the base catalyst,
wherein the at least one crosslinkable component comprising
reactive components A and B in the composition has a total hydroxy
number of less than 60 mg KOH/g solids.
2) The RMA crosslinkable composition according to claim 1, wherein
the at least one crosslinkable component comprising reactive
components A and B in the composition has a total hydroxy number
less than 20 mg KOH/g solids.
3) The RMA crosslinkable composition according to claim 1, wherein
the catalyst C is a carbonate salt according to formula
X.sup.+ROCO.sub.2.sup.-, wherein X.sup.+ is a non-acidic cation,
and R is hydrogen or a substituted or unsubstituted alkyl, aryl, or
aralkyl group.
4) The RMA crosslinkable composition according to claim 1, wherein
X.sup.+ is quaternary ammonium or phosphonium.
5) The RMA crosslinkable composition according to claim 1, wherein
the crosslinkable component comprising reactive component A is a
polymer comprising an average of 2 to 20 active C--H functions per
molecule.
6) The RMA cross-linking composition according to claim 1, wherein
more than 50% of the reactive components A in the crosslinkable
component are malonate groups.
7) The RMA crosslinkable composition according to claim 1, wherein
the component B comprises an unsaturated acryloyl or maleate
functional group.
8) The RMA crosslinkable composition according to claim 1,
comprising: a. between 5 and 95 wt % of a crosslinkable component
comprising component A with at least 2 acidic protons C--H in
activated methylene or methine, and b. between 5 and 95 wt % of a
crosslinkable component comprising component B with at least 2
activated unsaturated groups, wt % relative to the total weight of
the crosslinkable composition and c. a catalyst system C that
contains, or is able to generate a basic catalyst capable of
activating the RMA reaction between components A and B, wherein the
sum of the above-mentioned components is 100 weight percent and
wherein the at least one crosslinkable component comprising
reactive components A and B in the composition has a total hydroxy
number of less than 60 mg KOH/g solids.
9) The RMA crosslinkable composition according to claim 8, wherein
the catalyst system C contains or is able to generate a basic
catalyst capable of activating the RMA reaction between components
A and B, at levels of 0.0001 and 0.5 meq/g solid components.
10) The RMA crosslinkable composition according to claim 8, further
comprising an X--H group containing component D that is also a
Michael addition donor reactable with component B under the action
of catalyst C, wherein X is C, N, P, O or S.
11) The RMA crosslinkable composition according to claim 8, wherein
component D is present in quantities of at least 50 mole % relative
to base generated by component C, and less than 30 mole % of C--H
active groups from component A.
12) The RMA crosslinkable composition according to claim 8, further
comprising between 0.1 and 80 wt % of an organic solvent, which
contains at least lwt % of a primary alcohol and at least 0.1-10 wt
% water.
13) The RMA crosslinkable composition according to claim 8, wherein
the at least one crosslinkable component comprising reactive
components A and B in the composition has a total hydroxy number
less than 20 mg KOH/g solids.
14) A kit of parts for the manufacture of the crosslinkable
composition according to claim 1, comprising a part 1 comprising
the cross-linkable components comprising reactive components A
and/or B but no C, and part 2 comprising component C.
15) A polymeric or oligomeric resin A, for use in a RMA
crosslinkable composition according to claim 1, comprising one or
more reactive components A having a structure according to formula
1: ##STR00003## wherein R is hydrogen or an alkyl, aralkyl or aryl
substituent and Y and Y' are same or different alkyl, aralkyl or
aryl (R*), alkoxy (--OR*) groups or a polymer backbone or wherein
the --C(.dbd.O)--Y and/or --C(.dbd.O)--Y' is replaced by CN or
phenyl and which polymeric or oligomeric resin A has a hydroxy
number of less than 60 mg KOH/g solids, wherein the polymeric or
oligomeric resin is a polyester, polyether, polyepoxy, polyurethane
or polycarbonate, comprising reactive component A.
16) The resin A according to claim 15, wherein more than 50% of the
reactive components A in the crosslinkable component are malonate
groups.
17) The resin A according to claim 15, having a number molecular
weight between 100-20000 gr/mol, and an equivalent weight per
reactive component A of 100-2000 gr/mol, and an acid number less
than 4 mg KOH/gr.
18) A polymeric or oligomeric resin B for use in a RMA
cross-linkable composition according to claim 1 comprising one or
more reactive components B comprising C.dbd.C activated unsaturated
groups, and which polymeric or oligomeric resin has a hydroxy
number of less than 60 mg KOH/g solids, wherein the polymeric or
oligomeric resin B is a polyester, polyether, polyepoxy,
polyurethane or polycarbonate comprising reactive component B.
19) The resin B according to claim 18, having a number molecular
weight between 300 and 20000 gr/mol, having a equivalent weight per
reactive component A or B of 100-2000 gr/mol, an acid number less
than 4 mg KOH/gr.
20) Method for preparation of an RMA crosslinkable composition
comprising at least one crosslinkable component comprising reactive
components A and B each comprising at least 2 reactive groups,
wherein the at least 2 reactive groups of component A are C--H
acidic protons in activated methylene or methine groups, and the at
least 2 reactive groups of component B are C.dbd.C activated
unsaturated groups and a base catalyst C, which reactive components
A and B crosslink by Real Michael Addition reaction under action of
the base catalyst, wherein the at least one crosslinkable component
is a resin A, which resin A is a polymeric or oligomeric resin
comprising one or more reactive components A having a structure
according to formula 1: ##STR00004## wherein R is hydrogen or an
alkyl, aralkyl or aryl substituent and Y and Y' are same or
different alkyl, aralkyl or aryl (R*), alkoxy (--OR*) groups or a
polymer backbone or wherein the --C(.dbd.O)--Y and/or
--C(.dbd.O)--Y' is replaced by CN or phenyl and which polymeric or
oligomeric resin A has a hydroxy number of less than 60 mg KOH/g
solids, wherein the polymeric or oligomeric resin is a polyester,
polyether, polyepoxy, polyurethane or polycarbonate; or wherein the
at least one crosslinkable component is a resin B, which resin B is
a polymeric or oligomeric resin comprising one or more reactive
components B comprising C.dbd.C activated unsaturated groups, and
which polymeric or oligomeric resin has a hydroxy number of less
than 60 mg KOH/g solids, wherein the polymeric or oligomeric resin
B is a polyester, polyether, polyepoxy, polyurethane or
polycarbonate, or wherein the at least one crosslinkable component
is a mixture of resin A and resin B.
21) Method for the manufacture of coating compositions, films or
inks comprising: providing the crosslinking composition according
to claim 1.
22) Coating composition comprising the RMA crosslinkable
composition according to claim 1, and further comprising one or
more coating additives such as pigments, co-binders, or solvents.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of PCT application number
PCT/EP2012/069904 filed on 8 Oct. 2012, which claims priority from
European application number 11184439.5 filed on 7 Oct. 2011. Both
applications are hereby incorporated by reference in their
entireties.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a crosslinkable composition
cross-linkable by real Michael addition (RMA) reaction and resins
for use in said composition. Real Michael Addition is a reaction
wherein a reactive component B with at least 2 activated
unsaturated groups (hereafter also referred to as the RMA acceptor)
and a reactive component A with at least 2 acidic protons C--H in
activated methylene or methine groups (hereafter also referred to
as the RMA donor) react in the presence of a strong base
catalyst.
[0004] 2. Description of the Related Art
[0005] RMA chemistry can be tuned to give very fast curing
compositions (also at lower curing temperatures) in coating
compositions at acceptable or good pot lives and good material
properties, which makes this chemistry very attractive as a basis
for coating compositions. Details of RMA cross-linkable
compositions using a latent based cross-linking catalyst are
described by inventors of the present application in WO2011/055463
which is herewith incorporated by reference.
[0006] Real Michael addition is activated by strong bases. In
tuning the reactivity of coating systems in view of achieving a
desirable drying profile, there are various requirements to
balance. The drying profile (also referred to as the reaction
profile or as the curing profile) is the progress of the
cross-linking reaction as a function of time. It is required that
the drying profile allows build-up of mechanical properties as fast
as possible, to help the productivity of the coater. There is also
a desire for crosslinkable compositions that can be simply cured in
ambient conditions, as opposed to for example compositions
comprising photo-latent amine catalysts, known from T. Jung et al
Farbe and Lacke October 2003.
[0007] On the other hand, it is required to have a good appearance
of the resulting coating. This implies the need for sufficient
levelling during the immediate period after application, when the
curing coating composition is present as a liquid and capable of
such levelling. This also implies the need for absence of artefacts
like solvent inclusions or gas inclusions or other surface
irregularities that may occur if curing is very fast, especially if
it is faster at the surface than in deeper layers, which is often
the case if curing occurs at the time scale of solvent evaporation
or surface activation of a catalyst. Also, film hardness build-up
will be affected under conditions in which solvent entrapment
occurs. The described requirements are to some extent opposing each
other. For a fast curing profile high levels of catalyst are
preferred, whereas at the same time such high levels of catalysts
may negatively influence surface appearance and hardness
development.
BRIEF SUMMARY OF THE INVENTION
[0008] The object of the invention is to provide improved
cross-linkable compositions that provide optimum coating properties
in the delicate balance of these apparently counteracting
requirements, in particular in crosslinkable compositions having a
high solid content. In particular, there is a continuous desire to
improve the appearance and hardness of the coatings and the problem
is to provide RMA cross-linkable compositions that result in
coatings having improved appearance and hardness.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 illustrates the conversion of the acryloyl (as
followed by FTIR at 809 cm.sup.-1) in the preferred
acryloyl/malonate system using succinimid as component D.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0010] The following is a description of certain embodiments of the
invention, given by way of example only and with reference to the
FIGURE.
[0011] According to the invention there is provided an RMA
crosslinkable composition comprising at least one crosslinkable
component comprising reactive components A and B, each comprising
at least 2 reactive groups wherein the at least 2 reactive groups
of component A are acidic protons (C--H) in activated methylene or
methine groups and the at least 2 reactive groups of component B
are activated unsaturated groups (C.dbd.C) and a base catalyst (C)
which reactive components A and B crosslink by Real Michael
Addition (RMA) reaction under action of the base catalyst,
characterised in that the at least one crosslinkable component
comprising reactive components A and B in the composition have a
total hydroxy number of less than 60, preferably less than 40 and
more preferably less than 20 mg KOH/g solids. It was surprisingly
found that cross-linkable compositions comprising the special
cross-linkable components with very low hydroxy number show
significantly improved hardness and improved appearance as is
exemplified in the examples.
[0012] In a preferred embodiment the crosslinkable composition the
catalyst C is a carbonate salt according to formula X+ROCO2-,
wherein X+ is a non-acidic cation, preferably quaternary ammonium
or phosphonium, and R is hydrogen or a substituted or unsubstituted
alkyl, aryl, or aralkyl group. Details of this latent base catalyst
are described in WO2011/055463, which is herewith incorporated by
reference.
[0013] The reactive components A and B can be in the form of
separate molecules and each independently in the form of polymers,
oligomers, dimers or monomers. Therefore, a "cross-linkable
component comprising the active component A" is sometimes also
referred to herein as component A. Reactive components A and B can
be combined in a single molecule. Optionally, even catalyst C can
be combined in a single molecule with reactive component A and/or
B. It is preferred that the cross-linkable composition comprises an
oligomeric or polymeric resin A comprising reactive components A.
The invention also relates to oligomeric or polymeric resin A
comprising reactive components A having a hydroxy number of less
than 60, preferably less than 40, more preferably less than 20 and
optionally even less than 10 mg KOH/g solids.
[0014] The invention further relates to oligomeric or polymeric
resin B comprising reactive components B and having a hydroxy
number of less than 60, preferably less than 40 and more preferably
less than 20 mg KOH/g solids. The invention further relates to the
use of resin A or resin B or mixtures of resin A and B for the
preparation of RMA cross-linkable compositions.
Component A
[0015] Suitable examples of components A containing activated
methylene or methine groups are well known in the art. Preferred
are the oligomeric and/or polymeric components such as, for
example, polyesters, polyurethanes, polyacrylates, epoxy resins,
polyamides and polyvinyl resins containing reactive component A in
the main chain, pendant or both. Preferably, the polymer is a
polyester, polyurethane or polycarbonate.
[0016] The crosslinkable component comprising reactive components A
preferably is a polymer comprising one or more reactive components
A having a structure according to formula 2:
##STR00001##
wherein R is hydrogen or an alkyl, aralkyl or aryl substituent and
Y and Y' are same or different substituent groups, preferably
alkyl, aralkyl or aryl (R*), alkoxy (--OR*) or a polymer backbone
or wherein the --C(.dbd.O)--Y and/or --C(.dbd.O)--Y' is replaced by
CN or phenyl and which polymer has a hydroxy number of less than
60, preferably less than 40 and more preferably less than 20 mg
KOH/g solids. In case R is hydrogen, the CH2 is the activated
methylene and in case R is not hydrogen, the C--H is the activated
methine.
[0017] Good results can be obtained when the activated C--H group
containing component A is malonate (in Y and Y' are --OR* in
Formula 1) or acetoacetate (Y is --OR* and Y' is --R* in Formula
1). Preferably more than 50, preferably 60, 70, 80, 90 or 95% of
the reactive components A in the crosslinkable component are
malonate groups. Components containing both malonate and
acetoacetate groups in the same molecule are also suitable.
Additionally, physical mixtures of malonate and acetoacetate
group-containing components are suitable. The cross-linkable
component comprising reactive component A preferably is a polymer
comprising an average of 2 to 20, preferably 4 to 10 active C--H
functions per molecule.
[0018] In a most preferred embodiment of the crosslinkable
composition, component A is a malonate containing compound. It is
preferred that in the crosslinkable composition the majority of the
activated C--H groups are from malonate, that is more than 50%,
preferably more than 60%, more preferably more than 70%, most
preferably more than 80% of all activated C--H groups in the
crosslinkable composition are from malonate. In another embodiment,
the crosslinking composition comprises a component A, for example a
polymer, wherein more than 50%, preferably more than 70%, more
preferably more than 80% and most preferably more than 90% of the
activated C--H groups are from malonate and a separate component,
for example another polymer, oligomer or monomer, comprising
activated C--H groups not from malonate, for example
acetoacetate.
[0019] Especially preferred malonate group-containing components
for use with the present invention are the malonate
group-containing oligomeric or polymeric esters, ethers, urethanes
and epoxy esters containing 1-50, more preferably 2-10, malonate
groups per molecule. In practice polyesters and polyurethanes are
preferred. It is also preferred that such malonate group-containing
components have a number average molecular weight (Mn) in the range
of from about 100 to about 5000, more preferably, 250-2500, and an
acid number of about 2 or less. Also monomalonates can be used as
they have 2 reactive C--H per molecule. Monomeric malonates can, in
addition, be used as reactive diluents.
[0020] The invention also relates to a polymeric or oligomeric
resin A, for use in a RMA cross-linkable composition, comprising
one or more reactive components A having a structure according to
formula 2:
##STR00002##
wherein R is hydrogen or an alkyl, aralkyl or aryl substituent and
Y and Y' are same or different substituent groups, preferably
alkyl, aralkyl or aryl (R*), alkoxy (--OR*) or a polymer backbone
or wherein the --C(.dbd.O)--Y and/or --C(.dbd.O)--Y' is replaced by
CN or phenyl and which polymeric or oligomeric resin A has a
hydroxy number of less than 60, preferably less than 40 and more
preferably less than 20 mg KOH/g solids. Preferably, the polymeric
or oligomeric resin is a polyester, polyether, polyepoxy,
polyurethane or polycarbonate, more preferably a polyether,
polyester or polyurethane, comprising reactive components A,
preferably malonate or acetoacetate and preferably in an amount
that the resin comprises an average of 2 to 20, preferably 4 to 10
active C--H functions per molecule. Preferably, more than 50,
preferably 60, 70, 80, 90 or 95% of the reactive components A in
the crosslinkable component are malonate groups. Malonate
containing resin A is preferred over for example acetoacetate
containing resin A because it provides improved pot life and
coating hardness.
[0021] The resin A typically has a number molecular weight between
100-20000 gr/mol, preferably between 250 and 10000 and in view of
the rheology of the coating composition and the mechanical
properties of the obtained coating more preferably between 300 and
6000 gr/mol and preferably an equivalent weight per reactive
component A of 100-2000 gr/mol. The resin acid number this
preferably less than 4, preferably less than 3, 2 or 1 mg KOH/gr
because a high acid number would result in inactivation of at least
a part of the base catalyst.
Component B
[0022] Components B generally can be ethylenically unsaturated
components in which the carbon-carbon double bond is activated by
an electron-withdrawing group, e.g. a carbonyl group in the
alpha-position. Suitable components B are known in the art, for
example acryloyl esters, acrylamides, alternatively polyesters
based upon maleic, fumaric and/or itaconic acid (and maleic and
itaconic anhydride and polyesters, polyurethanes, polyethers and/or
alkyd resins containing pendant activated unsaturated groups.
Acrylates, fumarates and maleates are preferred. Most preferably,
the component B is an unsaturated acryloyl functional
component.
[0023] It is also especially preferred that the acid number of the
activated unsaturated group-containing components (as of any of
other component used in the composition) is sufficiently low to not
substantially impair activity of the catalyst, so preferably less
than about 2, most preferably less than 1 mg KOH/g. As exemplified
by the previously incorporated references, these and other
activated unsaturated group-containing components, and their
methods of production, are generally known to those skilled in the
art, and need no further explanation here. Preferably the
functionality is 2-20, the equivalent weight (EQW: average
molecular weight per reactive functional group) is 100-2000, and
the number average molecular weight preferably is Mn 200-5000.
[0024] The advantages of the invention are particularly manifest in
critically difficult compositions comprising not only a high solids
content but also aimed at a high crosslinking density, with
relative high concentrations and functionalities of functional
groups, for example in case the component A is a compound, in
particular an oligomer or polymer, comprising an average of 2 to
30, preferably 4 to 20 and more preferably 4-10 activate C--H per
polymer chain.
[0025] Typically, the concentrations of the functional groups in
components A and B, and their relative stoichiometry, are chosen
such that good film properties following cure may be expected, with
efficient use of these functional groups. Typically,
stoichiometries C--H/C.dbd.C are chosen o be from 0.1 to 10,
preferably 0.5 to 3, more preferably 0.7 to 3, most preferably
0.8/1.5.
[0026] The invention also relates to a polymeric or oligomeric
resin B for use in a RMA cross-linkable composition comprising one
or more reactive components B comprising activated unsaturated
groups (C.dbd.C), preferably unsaturated acryloyl or maleate
functional groups (preferably acryloyl) or an acrylamide and which
polymeric or oligomeric resin has a hydroxy number of less than 60,
preferably less than 40 and more preferably less than 20 mg KOH/g
solids. The resin B preferably is a polyester, polyether,
polyepoxy, polyurethane or polycarbonate comprising reactive
component B and preferably has a number molecular weight between
300 and 20000 gr/mol, preferably between 300 and 10000 or 6000
gr/mol. The prior art commonly uses TMPTA which has a molecular
weight of 296. The resin B preferably has a equivalent weight per
reactive component A or B of 100-2000 gr/mol and an acid number
less than 4, preferably less than 3, 2 or 1 mg KOH/gr.
[0027] The invention also relates to a resin mixture of polymeric
or oligomeric resin A and polymeric or oligomeric resin B as
described above for use in a RMA cross-linkable compositions and to
the use use of resin A or resin B or of a resin mixture of resin A
and resin B as cross-linkable components in an RMA cross-linkable
composition. Herein it is preferred that at least one of resin A or
resin B comprise at least 3 reactive cross-linking groups for
forming a three-dimensional cross-linked network and at least one
of resin A or resin B comprises at least two reactive cross-linking
groups and wherein resin A or B or both have an average of 3-30
reactive cross-linking groups per polymer or oligomer molecule.
Process for the Preparation of the RMA Resins A and B According to
the Invention.
[0028] The invention also relates to a process for the preparation
of the RMA resins A and B according to the invention, in
particular, to a process for the preparation of resin A comprising
transesterification of a polyol with reactive component A in the
form of an carboxylic acid ester (Y and Y' are alkoxy (--OR*)) and
to a process for the preparation of resin B comprising
transesterification of a polyol with reactive component B,
preferably an acryloyl, in the form of carboxylic acid ester or by
direct esterification of a polyol with reactive component B in the
form of carboxylic acid.
[0029] What is particularly important is that in the preparation
process of resin A or resin B the relative amounts of the
components in the reaction mixture and the reaction time in
combination with the reaction temperature are chosen such that the
resulting resin A or B has the required low hydroxy number of less
than 60, preferably less than 40 and more preferably less than 20
mg KOH/g solids. In reaction between a polyol and reactive
component A, the hydroxy value will be high in the beginning of the
reaction and will gradually decrease as hydroxy groups of the
polyol react with reactive component A. The skilled person can
calculate the required amounts of components such that the
resulting resin A on completion of the reaction has a very low
hydroxy value and can determine by known techniques, such as
acid-base titration whether the resulting resin has reacted
sufficiently long to reduce the hydroxy value to the required level
to form resin A or B.
[0030] The polyester resin used in the present invention can be
prepared by copolymerisation of one or more polyols, one or more
polyacids, and one ore more esters of malonic acid and/or
etylacetoacetic acid. A preferred way of preparing the polyesters
of present invention is to prepare in a first step a
hydroxylfunctional polyester, and in later step transesterifying
the polyester of the first step with esters of malonic or
ethylacetoacetic acid and a volatile alcohol, prefeably ethanol or
methanol.
[0031] The hydroxyfunctional polyester can also be prepared by
reacting a hydroxyl functional polyester polyol with chain
extenders, preferably lactones such as caprolactone, valerolactone,
and butyrolactone. Alternatively this hydroxypolyester can be
prepared by reacting a polyester bearing both hydroxyl and acid
groups with one or more mono or polyfunctional epoxy compounds.
Suitable mono or polyfunctional epoxy compounds are mono-, di- or
polyglycidyl ethers of (cyclo)aliphatic or aromatic hydroxyl
compounds such as allyl alcohol, butanol, cyclohexanol, phenol,
butyl phenol, decanol, ethylene glycol, glycerol, cyclohexane diol,
mononuclear di- or trifunctional phenols, bisphenols such as
Bisphenol-A or Bisphenol-F, and multinuclear phenols.
[0032] The polyols of the first step can also be prepared by
reacting a hydroxy functional polyester of the first step with a
mono- or polyfunctional isocyanate compound. As suitable at least
trifunctional isocyanates may be mentioned a wide variety of
monomeric and oligomeric polyfunctional isocyanates. The
polycarboxylic acids for the preparation of the polyester polyol
are preferably selected from the group of acyclic or cyclic
polycarboxylic acids, the esters or the anhydrides thereof. Cyclic
polycarboxylic acids include aromatic polycarboxylic acids and
cycloaliphatic polycarboxylic acids. Included in this
polycarboxylic acids are fatty acids, their esters, dimers and
higher oligomers and mixtures thereof. Also included are the esters
or the anhydrides thereof such as dimethyl ester and diethyl ester
of malonic acid, succinic anhydride, octenyl succinic anhydride
(any isomer or mixture of isomers of
4-octenyl-5-hydro-1,3furandione), dodecenyl succinic anhydride (any
isomer or mixture of isomers of
4-dodecenyl-5-hydro-1,3-furandione), and mixtures thereof.
[0033] The optionally co-condensed monocarboxylic acids may be
aliphatic, cycloaliphatic, aromatic or mixtures thereof.
Preferably, the monocarboxylic acid contains 6 to 18 carbon atoms,
most preferably 7 to 14 carbon atoms, such as octanoic acid,
2-ethylhexanoic acid, isononanoic acid, decanoic acid, dodecanoic
acid, benzoic acid, hexahydrobenzoic acid, and mixtures thereof.
Preferably, the polyol is a cycloaliphatic or aliphatic polyol
having 2 to 15 carbon atoms. Also preferred are mixtures of at
least one polyol selected from trimethylol ethane, trimethylol
propane, glycerol, pentaerythritol, and ditrimethylol propane with
at least one diol having 2 to 15 carbon atoms. Preferred diols
include 1,2ethane diol, 1,2-propane diol, 1,3-propane diol,
3-methyl-1,3-propane diol, 2butyl-2-ethyl-1,3-propane diol,
dimethylol propionic acid, and 1,4-cyclohexane dimethanol. Examples
of suitable monofunctional alcohols include alcohols with 6-18
carbon atoms such as 2-ethyl hexanol, dodecanol, cyclohexanol and
trimethyl cyclohexanol. The optionally co-condensed monocarboxylic
acids may be aliphatic, cycloaliphatic, aromatic or mixtures
thereof. Preferably, the monocarboxylic acid contains 6 to 18
carbon atoms, most preferably 7 to 14 carbon atoms, such as
octanoic acid, 2-ethylhexanoic acid, isononanoic acid, decanoic
acid, dodecanoic acid, benzoic acid, hexahydrobenzoic acid, and
mixtures thereof. Typical hydroxy acids that can be used include
dimethylol propionic acid, hydroxypivalic acid, and hydroxystearic
acid. Suitable monofunctional epoxy compounds include the glycidyl
esters of branched Monocarboxylic acids such as Cardura(R) E from
Resolution. Polyurethane, polyether polyols can be prepared in the
known manner using suitable monomers as described above.
[0034] Preferably, in view of the desired mechanical and appearance
properties of a coating prepared from the cross-linkable
composition, the oligomer or polymer constituents of resin A are
chosen such that the glass transition temperature of the resin A is
between -25 and +25.degree. C., more preferably between -20 and
+20.degree. C. and most preferably between -20 and +15.degree. C.
In combination with said resin A the glass transition temperature
of resin B can be chosen between wider ranges, preferably between
-50 and +25.degree. C. The resins can be aliphatic or a mix of
aliphatic and aromatic constituents with an aromatic constituents
percentage chosen in view of the envisaged application. The amount
of aromatic compounds in resin A and in resin B and also in a
mixture of resin A and Resin B is preferably at most 60 wt %
(relative to the total weight of the resin or resin mixture),
preferably at most 40, 20 or 10 wt %. Good results were obtained in
a preferred embodiment wherein resin A and resin B are aliphatic
resins, i.e. comprising substantially no aromatic constituents (at
most 5 wt %). In view of the RMA cross-linking the activity, the
acid number of resin A and B is preferably less than 1 mg KOH/g
solids. In view of the properties of the resulting coating and the
reaction kinetics, the molecular weight is preferably low between
300 and 6000 gr/mol. In view of achieving a good drying and coating
hardness, the hydroxy number is preferably as low as possible; most
preferably less than 20 and optionally even less than 10 mg KOH/g
solids. Even though the molecular weight is relatively low, in view
of the mechanical properties of the resulting coating, the Resins
must have sufficient cross-linking functionality. Preferably, resin
A and resin B have an average functionality of 3-30 reactive
cross-linking groups per polymer or oligomer molecule. For resin A
the functionality is preferably between 5 and 30, more preferably
between 10 and 30. Suitable combinations can be a mixture of resin
A with relatively high functionality and resin B with a relatively
low functionality, in particular resin A with functionality between
10 and 30 and resin B with a functionality of 3-20 or 3-10.
Component C
[0035] The base catalyst C can in principle be any known catalyst
suitable for catalyzing RMA reactions. Preferably, in view of
achieving good pot-life in combination with low temperature curing,
the cross-linking composition comprises a catalyst system C
comprising a strong based blocked by a volatile acid which is
activated by evaporation of this acid. A suitable catalyst system C
comprises a strong base blocked by a carbon dioxide, or the blocked
catalytic species are of formula ROCO2-, R being a optionally
substituted alkyl, preferably C1-C4 radical or hydrogen, preferably
the catalyst comprises a blocked base anion and a non-acidic
cation, preferably a quaternary ammonium or phosphonium cation.
Suitable catalyst C is described in WO2011/055463 herewith
incorporated by reference. It is preferred that the crosslinking
catalyst is utilized in an amount ranging between 0.001 and 0.3
meq/g solids, preferably between 0.01 and 0.2 meq/g solids, more
preferably between 0.02 and 0.1 meq/g solids (meq/g solids defined
as mmoles base relative to the total dry weight of the
crosslinkable composition, not counting particulate fillers or
pigments). Alternatively, the catalyst system C is activated by
reaction of an epoxy component with a tertiary amine, or an
anion.
[0036] For the CO2 deblocking catalyst systems, it was surprisingly
found that significantly better potlife could be achieved in a
composition wherein component A is a malonate, which composition
further comprises 0.1-10 wt %, preferably 0.1-5, more preferably
0.2-3 and most preferably 0.5-2 wt % water (relative to total
weight of the coating composition). Preferably, the amount of water
is chosen in an effective amount to increase gel time with at least
15 minutes, preferably at least 30 min, more preferably at least 1
h, even more preferably at least 5 h, and most preferably at least
24 h, 48 h. or at least 10%, 50% or 100% compared to the same
composition without water.
Component D
[0037] The cross-linkable composition may comprise as an additive
to improve appearance and or hardness of the coating an X--H group
containing component (D) that is also a Michael addition donor
reactable with component B under the action of catalyst C, wherein
X is C, N, P, O or S, preferably C, N or P, preferably present in
quantities of at least 50 mole % relative to base generated by
component C, and less than 30 mole % of C--H active groups from
component A.
[0038] Component D as described in an catalysed RMA crosslinkable
compositioncan create a reactivity profile comprising an initial
induction time of lowered reaction rate directly after application
and activation of the system, followed by a relative increase of
reactivity in later stages. This induction time can be tuned, to
allow a "open time" the period allowing flow and solvent and
entrapped air bubbles to escape. The induction time allows a
significantly higher amount of flow and levelling of the system,
avoiding surface defects that may result from very fast cure
without these additives, and better hardness build-up due to
reduced solvent entrapment, while still benefiting from the full
potential of the catalysts beyond this induction time, thus
creating an acceleration of the reaction at later stages to
complete crosslinking at higher rate than would be found if simply
using lower catalyst levels. Also the high sensitivity of lower
catalyst levels towards accidentally present acid contaminations is
avoided.
[0039] Although the advantages of the invention are apparent in
layers of normal thickness, the crosslinkable composition according
to the invention is particularly suitable for making thick layers.
Thick layers are considered to be layers having a cured dry
thickness of at least 50 or more than 70 micrometers. In thick
layer applications the risk of air and solvent inclusions is
higher. This is particularly pronounced in RMA crosslinkable
compositions that are cured at low temperature in the range from 10
to 60.degree. C. where resins are more viscous and levelling is
difficult.
[0040] The X--H group in component D has a higher acidity than the
C--H groups in component A, preferably being characterized in that
component D has a pKa (defined in aqueous environment) of at least
one unit, preferably two units, less than that of component A.
Preferably the pKa of the X--H group in component D is lower than
13, preferable lower than 12, more preferably lower than 11 most
preferably lower than 10. An excessive acidity may create problems
with components in the catalyst system; therefore hence the pKa is
preferably higher than 7, more preferably higher than 7.5 and
optionally higher than 8. The acidity difference assures that on
application of the coating, component D is activated (deprotonated)
preferentially over component A.
[0041] Preferably component D is selected from one or more
compounds from the group of Compounds D1 comprising C--H acidic
protons (X is C) in activated methylene or methine groups and
Compounds D2 comprising N--H acidic compound (X is N). Suitable
components D2 are an aza-acidic compounds (X is N) preferably
comprising a molecule containing the N--H as part of a group
Ar--NH--(C.dbd.O)--, --(C.dbd.O)--NH--(C.dbd.O)--, or of a group
--NH--(O.dbd.S.dbd.O)-- or a heterocycle in which the nitrogen of
the N--H group is contained in a heterocyclic ring, more preferably
component D2 is an imide derivative, preferably an (optionally
substituted) succinimide or glutarimide. Other suitable components
D2 are hydantoin derivatives, for example 5,5-dimethylhydrantoin,
sulfonamides, for example aromatic sulfonamides as benzene- or
toluenesulfonamide or heterocyclic compounds, for example triazoles
or a pyrazoles, or a uracil derivative.
[0042] In the crosslinkable composition, the X--H groups in
component D are present in an amount corresponding to at least 50
mole %, preferable at least 100 mole %, most preferably at least
150 mole % relative to the amount of base to be generated by
catalyst C. The appropriate amount is very much determined by the
acid base characteristics of component D relative to component A,
and the reactivity of the corresponding anions relative to B, so
may vary for different systems. It is noted that the open time
improving effect can in some cases be obtained at very small
amounts of component D, which is very advantageous because such
small amounts do not or not significantly affect the properties of
the resulting cured composition; for example the chemical and
mechanical properties of a coating. Typically the X--H groups in
component D are present in an amount corresponding to no more than
30 mole %, preferably no more than 20, optionally no more than 10
mole % relative to C--H donor groups from component A. Preferably,
the X--H functionality (number of groups per molecule) of component
D is low, preferably less than 4, more preferably less than 2, most
preferably it is 1.
[0043] The crosslinkable composition may comprise next to one or
more different components D a component D1 comprising acidic
protons (C--H) in activated methylene or methine groups having a
higher acidity than component A and which are also is reactive
towards component B, Such component D1 can also contribute to the
open time improving effect, however in order to have a significant
effect D1 should be typically be present in an amount between 10-40
mol % (relative to total RMA C--H), which is a significantly higher
amount than for component D.
[0044] The difference in acidity of the two C--H acidic components
A and D1 is chosen preferably in that wherein the pKa of component
D1 is between 0.5 and 6, preferably between 1 and 5 and more
preferably between 1.5 and 4 units lower than the pKa of component
A. Preferably, component A is a malonate containing component and
component D1 is an acetoacetate or acetylacetone containing
component, preferably of low C--H functionality (preferably less
than 10, more preferably less than 5, most preferably it is no more
than 2. Suitable components D and A2 are listed below with the pKa
value.
TABLE-US-00001 succinimide 9.5 ethosuximide 9.3
5,5-dimethylhydantoin 10.2 1,2,4-triazole 10.2 1,2,3-triazole 9.4
benzotriazole 8.2 benzenesulfonamide 10.1 nitromethane 10.2 isatine
10.3 uracil 9.9 4-nitro-2-methylimidazole 9.6 phenol 10.0
ethylacetoacetate 10.7 acetylacetone 9.0 diethylmalonate 13.0
[0045] The invention also relates to the use of the component D as
described above as an additive to RMA cross-linkable compositions.
The advantages of improved appearance and improved hardness can be
obtained irrespective of the thickness of the layer but are
particularly apparent in thick coating layers having a dry
thickness of at least 50, preferably at least 60, 75, 100 and more
preferably at least 125 micrometer, for the improvement of the open
time of the crosslinkable composition and for the improvement of
the appearance and hardness of the resulting cured composition, in
particular a coating.
[0046] In the crosslinkable composition the nature and amount of
component D is chosen to yield, under the application and curing
conditions chosen, an increase in time to get to a 30% conversion
level, of at least 3, preferably 5, more preferably 10 minutes,
preferably less than 60, more preferably less than 30 minutes, when
compared to the same composition without component D.
Solvent Component
[0047] The cross-linkable composition can be used without having
any additional solvent. This would typically be the case when the
cross-linkable components in the composition have sufficient low
viscosity and all components together form a solution. A solvent
may be added for example to reduce the viscosity in case of high
solids content of relatively high viscosity components, to mediate
the reaction kinetics or in case the composition contains certain
additives that would require the solvent. The solvent can be water
or can be an organic solvent or mixtures thereof. Most preferred is
to use an organic solvent. The organic solvent may contain
(substantially) no water. However, it is sometimes preferred in
view of increasing pot life to add in addition to organic solvent
also a relatively small amount of water, preferably between 0.1 and
10 wt % (relative to the total weight of the cross-linkable
composition).
[0048] For CO2 deblocking catalyst systems, the inventors further
found that advantages can be achieved in pot life if in the
crosslinkable composition at least part of the solvent is a primary
alcohol solvent. The solvent can be a mixture of a non-alcoholic
solvent and an alcohol solvent. Preferably, the alcohol is present
in an amount of at least 1, preferably 2, more preferably 3, most
preferably at least 5, even more preferably at least 10 wt %
relative to the total weight of the crosslinkable composition and
in view of VOC constraints preferably at most 45, preferably at
most 40 wt %, most preferably less than 30 wt %.
[0049] The alcohol solvent preferably is one or more primary
alcohols, more preferably a mono-alcohol having 1 to 20, preferably
1-10, more preferably 1-6 carbon atoms, preferably selected from
the group of ethanol, n-propanol, n-butanol, n-amyl alcohol and
butylglycol
[0050] In summary, the crosslinkable composition according to the
invention comprises [0051] a. between 5 and 95 wt % of a resin A
having reactive components A comprising at least 2 acidic protons
C--H in activated methylene or methine, said resin A having a
hydroxy number of less than 60, preferably less than 40 and more
preferably less than 20 mg KOH/g solids, and [0052] b. between 5
and 95 wt % of a resin B having reactive components B with at least
2 activated unsaturated groups (wt % relative to the total weight
of the crosslinkable composition) said resin B having a hydroxy
number of less than 60, preferably less than 40 and more preferably
less than 20 mg KOH/g solids and [0053] c. a catalyst system C that
contains, or is able to generate a basic catalyst capable of
activating the RMA reaction between components A and B, preferably
at levels of 0.0001 and 0.5 meq/g solid components, [0054] d.
optionally an X--H group containing component (D) that is also a
Michael addition donor reactable with component B under the action
of catalyst C, wherein X is C, N, P, O or S, preferably C, N or P,
preferably present in quantities of at least 50 mole % relative to
base generated by component C, and less than 30 mole % of C--H
active groups from component A, [0055] e. optionally between 0.1
and 80 wt % of solvent, preferably an organic solvent which
preferably contains at least 1 wt % of a primary alcohol and
optionally at least 0.1-10 wt % water [0056] wherein the sum of the
above-mentioned components is 100 weight percent and wherein the
resins A and B in the composition have a total hydroxy number of
less than 60, preferably less than 40 and more preferably less than
20 mg KOH/g solids.
[0057] Considering that the crosslinkable composition is a 2K
composition which is only formed shortly before the actual use, the
invention also relates to a kit of parts for the manufacture of the
composition according to the invention comprising a part 1
comprising components A and B but not C and part 2 comprising
component C. A kit of parts for the manufacture of the composition
according to the invention comprises a part 1 comprising the
cross-linkable components comprising reactive components A and/or B
but no C and part 2 comprising component C
[0058] The invention also relates to the use of the crosslinking
composition according to the invention in a method for the
manufacture of coating compositions, films or inks and to coating
compositions, inks or films comprising the crosslinking composition
according to the invention and further application oriented
additives for example one or more coating additives like pigments,
co-binder, solvents etc.
[0059] The invention also relates to a process for making a coating
layer having a fully cured dry thickness of at least 70, 75, 80 or
100 and more preferably at least 125 micrometer and having a good
surface appearance and hardness of the resulting cured composition
comprising mixing the components A, B with cayalyst C shortly
before use to form a coating composition according to the
invention, applying a layer of the coating composition on a
substrate and allowing the curing thereof at temperature between 0
and 60.degree. C.
[0060] The foregoing more general discussion of the present
invention will be further illustrated by the following specific
examples, which are exemplary only.
[0061] Molecular weights were measured by GPC in THF, and expressed
in polystyrene equivalent weights.
[0062] Persoz hardness measurement: Persoz pendulum hardness was
measured in a climatized room at 23.degree. C., and 55+/-5%
relative humidity. Hardness is measured with a pendulum acc. Persoz
as described in ASTM D 4366.
[0063] Drying time was determined by firmly pressing the thumb in
the paint film. The time was recorded when there was no visible
trace left in the paint film.
Resin Example According to the Invention
Preparation of Malonate Polyester Resin I
[0064] Into a reactor provided with a distilling column filed with
Raschig rings were brought 4.691 moles of neopentyl glycol, 2.173
moles of hexahydrophthalic anhydride and 0.0012 moles of butyl
stannoic acid. The mixture was polymerised at 240.degree. C. under
nitrogen to an acid number of 0.2 mg KOH/g. The mixture was cooled
down to 130.degree. C. and 2.819 moles of diethylmalonate were
added. The reaction mixture was heated to 170.degree. C. and
ethanol was removed under reduced pressure. The nearly colourless
material was cooled down and diluted with 178 g of butyl acetate to
a 85% solid content. The final resin had an acid number of 0.3 mg
KOH/g solids, an OH value of 8 mg KOH/g solids. The resin was
diluted to 85% solids with butyl acetate.
Resin Example According to the Invention
Preparation of Malonate Polyester Resin II
[0065] In a similar way as under (I) were brought 4.521 moles of
neopentyl glycol, 2.095 moles of hexahydrophthalic anhydride, 0.232
moles of Butyl ethyl propane diol and 0.0011 moles of butyl
stannoic acid were brought in a reactor. The mixture was
polymerised at 240.degree. C. under nitrogen to an acid number of
0.2 mg KOH/g. The mixture was cooled down to 130.degree. C. and
2.717 moles of diethylmalonate were added. The reaction mixture was
heated to 170.degree. C. and ethanol was removed under reduced
pressure. The nearly colourless material was cooled down and
diluted with 178 g of butyl acetate to a 85% solid content. The
final resin had an acid number of 0.3 mg KOH/g solids, an OH value
of about 30 mg KOH/g solids. The resin was diluted to 85% solids
with butyl acetate.
Comparative Resin Example
Preparation of Comparative Malonate Polyester Resin III
[0066] In a similar way as under (I) were brought 4.341 moles of
neopentyl glycol, 2.011 moles of hexahydrophthalic anhydride, 0.464
moles of Butyl ethyl propane diol and 0.0011 moles of butyl
stannoic acid were brought in a reactor. The mixture was
polymerised at 240.degree. C. under nitrogen to an acid number of
0.2 mg KOH/g. The mixture was cooled down to 130.degree. C. and
2.609 moles of diethylmalonate were added. The reaction mixture was
heated to 170.degree. C. and ethanol was removed under reduced
pressure. The nearly colourless material was cooled down and
diluted with 178 g of butyl acetate to a 85% solid content. The
final resin had an acid number of 0.3 mg KOH/g solids, an OH value
of about 60 mg KOH/g solids. The resin was diluted to 85% solids
with butyl acetate.
Preparation of Paint
[0067] Paints were prepared according the composition in the table.
The pigment was dispersed in the mixture of Disperbyk and Sartomer
(which is cross-linkable component B: DiTMPTA is
di-trimethylolpropane-tetraacrylate) with a high shear stirrer for
15 minutes. Then the other ingredients were added under stirring.
Prior to application the catalyst solution was added.
Preparation of the Catalyst Solution
[0068] A catalyst solution was formed as follows: to 8.03 g of a
55% solution of tetra-butylammoniumhydroxide were added 11.05 g of
diethylcarbonate and 6.74 g of isopropanol.
TABLE-US-00002 Sartomer SR355 17.77 17.59 17.41 Disperbyk 163 1.11
1.10 1.09 Kronos 2310 37.27 36.91 36.53 Example Resin I 29.95
Example Resin II 29.66 Comparative Resin III 29.36 OHV (mg KOH/g) 8
30 60 Sartomer SR355 1.71 1.69 1.67 Ethyl acetoacetate 1.66 1.64
1.63 Byk 310/315 [1:4] 0.28 0.28 0.27 Succinimide 0.44 0.43 0.43
Benzotriazole 0.00 0.00 0.00 Methyl ethyl ketone 3.35 3.32 3.29
Butyl acetate 1.17 1.16 1.15 Propanol 0.56 0.55 0.55 Thinner 4.66
4.61 4.57 Catalyst solution 2.51 2.48 2.46 Total 100.00 100.00
100.00 Hardness Persoz (after 3 118 88 19 days) Drying time 1 h 10
+4 hrs +24 hrs
[0069] The examples above show that the hardness of the coating
composition strongly depends on the hydroxy value of the resin. A
hydroxy value of 60 or more will lead to an unacceptable long
drying time and a very slow hardness built.
PRIOR ART
Comparative Resin Example
[0070] WO 2011/055463, describes in Example 4 Formulations made
from a malonate polyester component A-1 and TMPA as the
cross-linkable component B-1 and various catalysts. The malonate
polyester A-1 had an OH value of 83.2 mg KOH/g. Apart from the
hydroxy value, the malonate polyester A-1 is similar to the above
described malonate polyester I and II. The catalyst C-5
(tetrabutylammonium ethylcarbonate) that has been used is the
catalyst used in the above paint formulations. The Perzos hardness
was 65 after 1 month curing time, whereas the resin according to
the invention having a low hydroxy value as a significantly higher
hardness (88) already after three days curing time.
[0071] The invention will be further illustrated by the following
specific examples, which are exemplary only.
[0072] Molecular weights were measured by GPC in THF, and expressed
in polystyrene equivalent weights. Viscosities were measured with a
TA Instruments AR2000Rheometer, using a cone and plate setup (cone
4 cm 1.degree.) at 1 Pa stress.
[0073] Tube and ball method for pot life determination: A flat
bottomed test tube (internal diameter 15 mm, length 12.5 cm),
carrying two marks, 5 cm apart is filled with 20 ml of paint. A
steel ball with a diameter of 8 mm is added, and the tube is closed
with a snap cap. The tube is held under an angle of 10.degree. and
the steel ball is allowed to roll on the wall of the test tube. The
time needed to roll between the two marks is taken as a measure for
the viscosity. The time needed to double in viscosity is taken as
the pot life. If necessary this time is calculated by linear
interpolation between two measurements. This method was used for
the pigmented formulations. For the clear formulations, a glass
test tube (length 12 cm, diameter 13 mm) was filled with a
stainless steel ball of 12 mm diameter, and the formulation to be
studied to leave a very limited head space, and closed. Time was
recorded for the ball to fall and pass a distance of 5 cm when the
tube was tilted vertically. An average was taken over 2
measurements.
[0074] Drying recorder drying time: For determining the recorder
drying time, paint was applied on a glass panel with a doctor blade
with a 90.mu. gap. The drying time was measured with a Gardco
electronic drying time recorder, type DT-5020, set on a cycle time
of 60 minutes. Drying time was recorded as the time were the stylus
left no more visible trace on the film.
[0075] TNO cotton ball drying times: Dust-dry and tack-free times
were measured according to the so-called TNO method with a wad of
cotton-wool. Dust-dry time means the time needed for the coating
after dropping the wad on the surface of the coating and after
leaving it there for 10 seconds, to get no residue of the
wool-cotton sticking onto the surface after blowing away the wad.
For tack-free time the same holds but now a weight load of 1 kg is
applied on the wad for 10 seconds.
[0076] Persoz hardness measurement: Persoz pendulum hardness was
measured in a climatized room at 23.degree. C., and 55+/-5%
relative humidity. Hardness is measured with a pendulum acc. Persoz
as described in ASTM D 4366. For the gradient layer thickness
panels, hardness is measured at different spots and corresponding
layer thickness is measured. If necessary the hardness at a certain
layer thickness is calculated by linear interpolation of the
measurement at two different layer thicknesses. Layer thicknesses
were measured with a Fischer Permascope MP40E-S.
[0077] Optical evaluation spayed pigmented paints: Paint was
sprayed with a devilbiss spraygun, nozzle FF-1.4 with an air
pressure of 3.5 bar. The paint was prayed in a continuous layer
over the entire surface of a 55.times.10 cm steel panel. A
consecutive layer was sprayed starting 10 cm from the right edge.
Several layers were built up, moving to the right so that a layer
thickness gradient was build up from the left to right. Films were
allowed to dry horizontally at 23.degree. C., 45% RH. Layer
thicknesses were measured with a Fischer Permascope MP40E-S. At
100.mu. layer thickness, a picture was taken with an Olympus SZX10
microscope (1.times. magn) equipped with a digital camera.
[0078] Wavescan analysis: The panels as described above were
analyzed using the Wavescan II of Byk instruments. Data were stored
using Autochart software from Byk. Analysis was done in the
direction perpendicular to the thickness gradient. In this
instrument the light of small laser diode is reflected by the
surface of the sample under an angle of 60.degree., and the
reflected light is detected at the gloss angle (60.degree.
opposite). During the measurement, the "wave-scan" is moved across
the sample surface over a scan length of approx. 10 cm, with a data
point being recorded every 0.027 mm. The surface structure of the
sample modulates the light of the laser diode. The signal is
divided into 5 wavelength ranges in the range of 0.1-30 mm and
processed by mathematical filtering. For each of the 5 ranges a
characteristic value (Wa 0.1-0.3 mm, Wb 0.3-1.0 mm, We 1.0-3.0 mm,
Wd 3.0-10 mm, We 10-30 mm) as well as the typical wave-scan-values
longwave (LW, approx. 1-10 mm) and shortwave (SW, approx. 0.3-1 mm)
is calculated. Low values mean a smooth surface structure.
Additionally a LED light source is installed in the wave-scan DOI
and illuminates the surface under 20 degrees after passing an
aperture. The scattered light is detected and a so-called dullness
value (du, <0.1 mm) is measured. By using the three values of
the short wave range Wa, Wb and du a DOI value is calculated. (see
Osterhold e.a., Progress in Organic Coatings, 2009, vol. 65, no4,
pp. 440-443).
[0079] The following abbreviations were used for chemicals used in
the experiments: DiTMPTA is di-trimethylolpropane-tetraacrylate
(obtained from Aldrich (MW=466 g/mol)) or used as Sartomer SR355
(supplied commercially by Sartomer); Disperbyk 163 is a dispersant
commercially supplied by Byk; Byk 310 and 315 are additives
commercially supplied by ByK; Kronos 2310 is a TiO2 pigment
commercially supplied by Kronos, TBAH is tetrabutylammonium
hydroxide, BuAc is Butyl acetate, MEK is Methyl ethyl ketone
(2-Butanone); EtAcAc is ethyl acetoacetate; DEC is diethyl
carbonate; IPA is isopropanol; RT is room temperature.
Preparation of Malonate Polyester A According to the Invention
[0080] Into a reactor provided with a distilling column filed with
Raschig rings were brought 17.31 mol of neopentyl glycol, 8.03 mol
of hexahydrophthalic anhydride and 0.0047 mol of butyl stannoic
acid. The mixture was polymerised at 240.degree. C. under nitrogen
to an acid number of 0.2 mg KOH/g. The mixture was cooled down to
130.degree. C. and 10.44 mol of diethylmalonate was added. The
reaction mixture was heated to 170.degree. C. and ethanol was
removed under reduced pressure. The nearly colourless material was
cooled down and diluted with 420 g of butyl acetate to a 90% solid
content. The final resin had an acid number of 0.3 mg KOH/g solids,
an OH value of 20 mg KOH/g solids and a weight average molecular
weight of 3400 Da.
Catalyst Solution C1
[0081] Catalyst solution was prepared by reacting 59.4 g a TBAH
solution (40% in water) with 13.5 g DEC (reacting overnight at RT),
with 14.5 g isopropanol as co-solvent, following the corresponding
ethocarbonate species development. Titration indicated that
blocking was complete, and that the concentration of blocked base
was 0.83 meq/g solution.
Catalyst Solution C2
[0082] To 43.6 g of a 45% aqueous solution of TBAH were added 36.6
g of isopropanol and 60 g of DEC. After standing overnight the
mixture was filtered over paper. Titration showed that the catalyst
contained 0.52 meq of blocked base per gram solution.
No-D Example Formulation 1, Example Formulations 1-4
[0083] Formulations were prepared based on a malonate donor resin
A, DiTMPTA as acryloyl donor resin, and the indicated amount of
succinimide, and thinned to a viscosity of 160 mPas with a mixture
of MEK/BuAc 1:1 by volume. This was mixed with an amount of
catalyst solution C1. Listed in table A are the details of the
overall composition. Catalyst amounts are 50 meq/g solids, water
levels are 1.8 wt %, isopropanol at 0.7 wt %, ethanol level
estimated at 0.2 wt %.
TABLE-US-00003 TABLE A Code No-D1 Ex1 Ex2 Ex3 Ex4 malonate ester
A/g 15.0 15.0 15.0 15.0 15.0 di-TMPTA/g 6.6 6.6 6.6 6.6 6.6
succinimide/mg 0 149 174 199 298 mole % succinimide on cat 0 150
175 200 300 MEK/BuAc (1:1)/g 4.5 4.5 4.5 4.5 4.5 catalyst C1/g 1.2
1.2 1.2 1.2 1.2
[0084] Of these formulations, the drying behaviour at room
temperature for films leading to a dry film thickness of around
70-75 mu was followed with TNO cotton ball drying tests, and Persoz
pendulum hardness development was determined; also these results
are listed in Table B.
TABLE-US-00004 TABLE B Code No-D1 Ex1 Ex2 Ex3 Ex4 mole %
succinimide on cat 0 150 175 200 300 TNO-drying dust-dry (min) 10'
25' 25' 30' 65' tack-free (min) 10' 30' 30' 35' 70' Persoz hardness
(sec) after time at RT: 4 h 31 107 132 1 night 42 126 152 1 week 66
131 137 146 231
[0085] It can be seen that whereas No-D example 1 shows an
extremely fast drying, the actual Persoz hardness levels are low
presumably due to solvent entrapment in the system. Moreover, the
appearance of this No-D example 1 is poor. Upon addition of low
levels of succinimide (slightly higher than the levels of catalyst
used), some retardation of the drying is seen, but still giving
drying times considered as fast; however, it can also be observed
that the Persoz hardness development is strongly improved.
Simultaneously, the example films with succinimide exhibit a better
appearance than No-D example 1.
[0086] Example formulations 5-7, and No-D example formulations 2-3
were prepared as pigmented paints, having compositions as tabulated
in Table C (amounts in grams).
TABLE-US-00005 TABLE C Code Ex5 Ex6 Ex7 No-D2 No-D3 Sartomer SR355
38.19 38.19 38.19 38.19 39.19 Disperbyk 163 2.39 2.39 2.39 2.39
2.39 Kronos 2310 80.12 80.12 80.12 80.12 80.12 malonate polyester A
58.70 67.69 67.69 58.70 67.69 Sartomer SR 355 4.22 1.15 1.15 4.22
4.22 EtAcAc 4.81 0.00 0.00 4.81 0.00 Byk 310/315 [1:4 by mass] 0.60
0.60 0.60 0.60 0.60 Succinimide 0.79 0.79 1.58 0.00 0.00 BuAc 2.52
2.52 2.52 2.52 2.52 MEK 7.20 7.20 7.20 7.20 7.20 catalyst solution
C2 9.34 9.34 9.34 9.34 9.34 recorder drying time (min) 14 15 44 4.3
8 potlife (min) 39 35 37 17 29 Persoz hardness (sec) after 147 147
145 85 66 24 h (50 mu dry film)
[0087] Pot life of these pigmented paints were measured, and drying
times of these paints drawn onto glass panels were determined with
a drying recorder. These paints were also applied by spraying onto
a steel panel to obtain gradient film thickness panel. Persoz
hardness at 50 mu dry film thickness was determined after 24 hr RT
cure; microscope pictures were taken of the resulting coatings on
these panels at approximately 100 mu dry film thickness. Also, pot
life of these paints were measured. Results are included in table
C.
[0088] It can be observed from a comparison of No-D example 3 with
examples 6 and 7, that the addition of succinimide to the
formulation gives clear advantages in Persoz hardness build-up, and
some advantage in pot life. Example 7, with a higher level of
succinimide, shows a significant increase in drying time, the 44
minute value can however still be considered as an acceptable to
good value. Appearance of panels from examples 6 and 7 is much
better than that of panels from No-D example 3, as can be judged
from comparing the microscope photographs, No-D example 3 showing
many more defects.
[0089] Similar conclusions can be drawn from a comparison of No-D
example 2, with example 5, now based on a formulation with
acetoacetate included besides malonate as RMA donor groups. Example
5 (with succinimide added) exhibits higher Persoz hardness, a
better pot life, and a better appearance than No-D example 2 (not
containing succinimide).
[0090] Example 8 was prepared and evaluated in a similar way as
discussed above for example 5-7, the composition and results given
below in table D (amounts in grams). It can be seen that the
additional presence of 1,2,4-triazole (when compared to example 6)
leads to a significant improvement in pot-life, other advantages
being retained.
TABLE-US-00006 TABLE D Code Ex8 Sartomer SR355 38.19 Disperbyk 163
2.39 Kronos 2310 80.12 Malonate polyester A 67.69 Sartomer SR 355
1.15 EtAcAc 0.00 Byk 310/315 [1:4 by mass] 0.60 1,2,4-triazole 0.96
Succinimide (s) 0.79 BuAc 2.52 MEK 7.20 catalyst solution C2 9.34
recorder drying time (min) 16 Potlife (min) 70 Persoz hardness
(sec) after 24 h (50 147 mu dry film)
[0091] Example formulations 9 and 10, and No-D example formulations
4 and 5 were formulated and evaluated along similar lines, now also
including Wavescan analysis to have a quantitative indication of
the quality of the appearance. Compositions and results are given
in Table E (amounts in grams).
TABLE-US-00007 TABLE E Code Ex9 Ex10 No-D4 No-D5 Sartomer 19.07
19.07 19.07 19.07 Disperbyk 163 1.19 1.19 1.19 1.19 Kronos 2310
40.01 40.01 40.01 40.01 Malonate polyester A 29.35 33.85 29.35
33.85 Sartomer SR 355 2.11 0.58 2.11 0.58 EtAcAc 2.41 -- 2.41 --
Byk 310/315 [1:4 by mass] 0.30 0.30 0.30 0.30 Succinimide 0.40 0.40
-- -- BuAc 1.26 1.26 1.26 1.26 MEK 3.60 3.60 3.60 3.60 Catalyst
solution C2 4.67 4.67 4.67 4.67 Persoz hardness (s) at 50 .mu. 122
125 97 93 Layer thickness (.mu.) 51 56 58 58 du (dullness) 6.30
6.40 8.80 11.30 Longwave 3.80 1.90 5.30 7.80 Shortwave 2.20 6.40
18.20 24.10 DOI (Dorigon) 94.10 93.90 91.50 88.40 Layer thickness
(.mu.) 92 93 92 86 du (dullness) 5.90 8.70 11.60 23.40 Longwave
1.00 3.70 11.50 25.10 Shortwave 9.50 24.90 29.70 60.60 DOI
(Dorigon) 94.10 90.20 88.10 74.90
[0092] Example formulation 9 can be compared with No-D formulation
example 4, example formulation 10 can be compared with No-D
formulation example 5, difference being the presence of low amounts
of succinimide. It can from both comparisons be concluded that the
presence of succinimide, besides the improved Persoz hardness,
leads to significantly improved values for longwave and shortwave
roughness, dullness and DOI.
Example 11
Impact on Conversion Kinetics
[0093] The conversion of the acryloyls in the system can be
followed by FTIR, focusing on the 809 cm.sup.-1 band characteristic
of the acryloyl. Doing that, the impact of added succinimide on
total conversion can be made visible. Two systems were formulated
(according to compositions of No-D example 1 (without succinimide)
and example formulation 1 (with 150% succinimide relative to
solids). FIG. 1 compares the conversion of these systems after
application on top of an ATR crystal, the IR beam probing the
deepest layers, close to the substrate. Initial conversion of the
formulation without the succinimide is fast, which is also the
cause for solvent entrapment and potential appearance problems. It
can be seen that the addition of succinimide, even at these very
low levels, leads to a significant retardation of the initial
conversion; simultaneously, it illustrates that after this initial
retardation period, the conversion rate is accelerating, so that
the rate of cure towards higher conversions is still fast after
this initial delay.
Example 12
Determination of Michael Addition Reactivity of Succinimide
[0094] 5 grams of succinimide (50.5 mmole) were dissolved in a
mixture of 42 grams of butyl acrylate and 42 grams of methanol, and
maintained at room temperature as such, or after adding a strong
base (9.82 grams of a 1.12 meq/g solution of tetrabutylammonium
hydroxide in methanol, 11 meq). Subsequently, the concentration of
succinimide is determined as a function of time by taking samples,
neutralizing with a known excess of HCl in water, and backtitration
with a KOH solution. Without base initiation, no significant loss
of succinimide N--H in this solution is observed in two weeks. With
the base added, the succinimide concentration can be seen to
decrease with time, as illustrated in the table F below.
Succinimide concentration is expressed as % relative to the
theoretical level based on used amounts.
TABLE-US-00008 TABLE F Time (min) Succinimide remaining (%) 3 99 30
87 60 77 120 60 180 48
[0095] At this catalyst level ([succinimide]/[base]=5), it takes
about an hour to lose 25% of the succinimide acidic protons to be
consumed. Under these conditions, dimethylmalonate (instead of
succinimide) would react much faster with the acrylate.
[0096] Further modifications in addition to those described above
may be made to the structures and techniques described herein
without departing from the spirit and scope of the invention.
Accordingly, although specific embodiments have been described,
these are examples only and are not limiting upon the scope of the
invention.
* * * * *