U.S. patent application number 12/669573 was filed with the patent office on 2010-07-29 for resin system for intumescent coating with enhanced metal adhesion.
This patent application is currently assigned to EVONIK ROEHM GMBH. Invention is credited to Heike Heeb, Gilbert Kuehl, Peter Neugebauer, Peter Reinhard, Guenter Schmitt, Sybille Scholl.
Application Number | 20100190886 12/669573 |
Document ID | / |
Family ID | 39791278 |
Filed Date | 2010-07-29 |
United States Patent
Application |
20100190886 |
Kind Code |
A1 |
Schmitt; Guenter ; et
al. |
July 29, 2010 |
RESIN SYSTEM FOR INTUMESCENT COATING WITH ENHANCED METAL
ADHESION
Abstract
The invention relates to an intumescent coating with improved
metal adhesion.
Inventors: |
Schmitt; Guenter;
(Darmstadt, DE) ; Neugebauer; Peter; (Limburg,
DE) ; Scholl; Sybille; (Rodenbach, DE) ; Heeb;
Heike; (Nauheim, DE) ; Reinhard; Peter;
(Dreieich-Dreieichenhain, DE) ; Kuehl; Gilbert;
(Hanau, DE) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
EVONIK ROEHM GMBH
DARMSTADT
DE
|
Family ID: |
39791278 |
Appl. No.: |
12/669573 |
Filed: |
June 25, 2008 |
PCT Filed: |
June 25, 2008 |
PCT NO: |
PCT/EP08/58047 |
371 Date: |
January 19, 2010 |
Current U.S.
Class: |
523/179 |
Current CPC
Class: |
C09D 4/06 20130101; Y10T
428/31692 20150401; Y10T 428/31895 20150401; C09D 5/185
20130101 |
Class at
Publication: |
523/179 |
International
Class: |
C09K 21/14 20060101
C09K021/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 20, 2007 |
DE |
10 2007 034 458.0 |
Claims
1. Resin system for an intumescent coating comprising at least one
ethylenically unsaturated monomer component, characterized in that
there is at least one polymeric component comprising an acid
(meth)acrylate or copolymerizable polyfunctionalized carboxylic
acids present.
2. Resin system for an intumescent coating according to claim 1,
characterized in that the acid (meth)acrylate is selected from the
group of dicarboxylic acids.
3. Resin system for an intumescent coating according to claim 2,
characterized in that the acid (meth)acrylate is selected from the
group of beta-CEA.
4. Resin system for an intumescent coating according to claim 1,
characterized in that the copolymerizable polyfunctionalized
carboxylic acids are selected from the group of itaconic acids,
fumaric acids or maleic acids.
5. Resin system for an intumescent coating according to claim 1,
characterized in that one polymeric component is selected from the
group of thermoplastic resins.
6. Resin system for an intumescent coating according to claim 5,
characterized in that one polymeric component is selected from the
group of homopolymers, copolymers and/or terpolymers of a
(meth)acrylic resin.
7. Resin system for an intumescent coating according to claim 1,
characterized in that one polymeric component comprises a
(meth)acrylate copolymer.
8. Resin system for an intumescent coating according to claim 1,
characterized in that one polymeric component comprises one methyl
(meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate,
isobutyl (meth)acrylate, tert-butyl (meth) acrylate, 2-hydroxyethyl
(meth)acrylate, 2-hydroxypropyl (meth)acrylate and/or 2-ethylhexyl
(meth)acrylate.
9. Resin system for an intumescent coating according to claim 1,
characterized in that one polymeric component comprises a reaction
product of one or more dienes with at least one of styrene,
vinyltoluene, vinyl chloride, vinyl acetate, vinylidene chloride
and/or vinyl ester.
10. Resin system for an intumescent coating according to claim 1,
characterized in that one ethylenically unsaturated monomer
component comprises one methacrylate or acrylate functionality.
11. Resin system for an intumescent coating according to claim 9,
characterized in that one ethylenically unsaturated monomer
component comprises methyl (meth)acrylate, ethyl (meth)acrylate,
n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl
(meth)acrylate, 2 hydroxyethyl (meth)acrylate, 2-hydroxypropyl
(meth)acrylate and/or 2-ethylhexyl (meth)acrylate.
12. Process for curing an intumescent coating comprising a resin
system according to claim 1, characterized in that at least one
ethylenically unsaturated monomer component and at least one
polymeric component comprising an acid (meth)acrylate or
copolymerizable, polyfunctionalized carboxylic acids and the
typical intumescent auxiliaries and additives are polymerized by
means of free radical polymerization.
13. Process for curing an intumescent coating according to claim
11, characterized in that auxiliaries and additives used are
initiators, preferably organic peroxides.
14. Process for curing an intumescent coating according to claim
12, characterized in that initiators used are dialkyl peroxides,
keto peroxides, peroxy esters, diacyl peroxides, hydroperoxides
and/or peroxy ketals.
15. Use of the intumescent coating according to claim 1 for coating
metal surfaces and wood surfaces.
Description
[0001] The invention relates to a resin system for an intumescent
coating with improved metal adhesion.
[0002] Intumescent coatings are used to protect steel, and steel
girders, from fire damage in construction. Conventional systems are
provided with a variety of intumescent adjuvants, which when
exposed to heat react together and form an insulating foam
exhibiting low thermal conduction. This foam reduces the heating of
the steel and so prolongs the time before the steel loses its
supporting function. Additional evacuation time is gained.
[0003] Known coating systems are based on high molecular mass
thermoplastic resins based on acrylates, methacrylates and/or
vinyls and require a high solvent or water fraction for application
to the corresponding metal surface. This leads to long drying
times, in some cases very long, particularly when very thick coats
are applied. For reasons of environmental protection, water-based
coatings are being used increasingly, but require longer drying
times, especially in regions with high atmospheric humidity.
[0004] The intumescent coating is typically applied on-site during
the construction phase. Preference is given, however, to in-shop
applications, since these can take place under controlled
conditions. In the case of slow drying, however, an impractical
cycle time results, because the components cannot be moved until
drying is complete.
[0005] Epoxy-based intumescent coatings are used with preference in
the offshore industry. They are distinguished by effective ageing
stability and relatively short drying times. Polyurethane systems
are a subject of intense investigation. They likewise feature a
relatively short drying time and effective water resistance. Here,
however, fire tests have had negative outcomes, owing to the poor
adhesion of the coating to the steel [Development of alternative
technologies for off-site applied intumescent coatings, Longdon, P.
J., European Commission [Report] EUR (2005), EUR 21216, 1-141].
[0006] The object was to provide an improved resin for an
intumescent coating.
[0007] The object, moreover, was to provide a process for the
production of the resin.
[0008] The object has been achieved by a resin system for an
intumescent coating comprising at least one ethylenically
unsaturated monomer component, characterized in that there is at
least one polymeric component comprising an acid (meth)acrylate or
copolymerizable polyfunctionalized carboxylic acids present.
[0009] Surprisingly it has been found that the new resin system as
a binder for intumescent coatings has outstanding adhesion
properties to metallic surfaces, particularly to steel.
[0010] The resin system can also be used as a wood coating.
[0011] The coatings of the invention can be used both on-site and
in-shop.
[0012] It has been found that the intumescent coatings comprising
the new resins dry cure very quickly. Drying times of approximately
1 hour are achieved. Through the addition of more curing agents it
is possible to lower the curing time further. Accordingly the
preferred in-shop application can take place within acceptable
cycle times.
[0013] It has been found, moreover, that the quick-drying and
well-adhering resins for intumescent coatings are also
outstandingly suitable for thick coating films, for example 1-5
mm.
[0014] Crosslinkers used are more particularly polyfunctional
methacrylates such as allyl methacrylate, ethylene glycol
dimethacrylate, diethylene glycol dimetacrylate, triethylene glycol
dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene
glycol dimethacrylate, 1,3-butanediol dimethacrylate,
1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate,
1,12-dodecanediol dimethacrylate, glycerol dimethacrylate and
trimethylolpropane trimethacrylate.
[0015] Resin systems for the coating of metal surfaces are known.
Intumescent coatings are described in particular in WO
2005/000975.
[0016] The coating preferably comprises one thermoplastic polymer
resin in combination with low molecular mass monomers or oligomers
having ethylenically unsaturated double bonds, in the form for
example of alpha-beta ethylenically unsaturated carboxylic ester
groups such as methacrylate or acrylate groups, for example. The
notation (meth)acrylate here denotes not only methacrylate, such as
methyl methacrylate, ethyl methacrylate, etc., for example, but
also acrylate, such as methyl acrylate, ethyl acrylate, etc., for
example, and also mixtures of both.
[0017] One thermoplastic polymer is preferably a (meth)acrylate
resin in the form of homopolymer, copolymer and/or terpolymer. With
particular preference a polymer component is a (meth)acrylate
polymer. This polymer can be prepared via the polymerization of one
or more methacrylate or acrylate monomers, preferably from the
group of methyl (meth)acrylates, ethyl (meth)acrylate, n-butyl
(meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate,
2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl (meth)acrylate and/or
2-ethylhexyl (meth)acrylate. Co-reagents may be styrene or
vinyltoluenes. One particularly preferred thermoplastic polymer is
a copolymer of butyl methacrylate and methyl methacrylate.
[0018] One ethylenically unsaturated monomer component comprises at
least one methacrylate or acrylate functionality.
[0019] One ethylenically unsaturated monomer component is
preferably selected from the group of methyl (meth)acrylate, ethyl
(meth)acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate,
tert-butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate,
2-hydroxypropyl (meth)acrylate and/or 2-ethylhexyl
(meth)acrylate.
[0020] Another class of thermoplastic polymer resins comprises
homopolymers, copolymers or terpolymers of vinyl monomers such as
styrene, vinyltoluene, vinyl chloride, vinyl acetate, vinylidene
chloride and/or vinyl esters. Co-reagents may be dienes, such as
butadiene, for example.
[0021] The thermoplastic resins form 10%-60% by weight of the resin
component of the coating mixture.
[0022] One polymeric component may comprise methyl (meth)acrylate,
ethyl (meth)acrylate, n-butyl (meth)-acrylate, isobutyl
(meth)acrylate, tert-butyl (meth)-acrylate, 2-hydroxyethyl (meth)
acrylate, 2-hydroxy-propyl (meth)acrylate and/or 2-ethylhexyl
(meth)-acrylate.
[0023] One polymeric component may also comprise a reaction product
of one or more dienes with at least one styrene, vinyltoluene,
vinyl chloride, vinyl acetate, vinylidene chloride and/or vinyl
ester.
[0024] At least one of the liquid monomer components comprises
methacrylate functionalities, with particular preference
methacrylic esters. If desired it is also possible for an acrylate
functionality to be present, preferably acrylic esters.
[0025] Moreover, the monomer component is monofunctional, so that
the reaction product with an organic peroxide is thermoplastic and
melts and flows up to the reaction temperature of the intumescent
additives.
[0026] By way of example (meth)acrylic esters are selected from the
group of methyl (meth)acrylates, ethyl (meth)-acrylates, n-butyl
(meth)acrylates, isobutyl (meth)-acrylates, tert-butyl (meth)
acrylates, 2-ethylhexyl (meth)acrylates and mixtures thereof.
Methyl methacrylate and 2-ethylhexyl acrylate are particularly
preferred.
[0027] The liquid monomer component forms 30%-60% by weight of the
resin component of the coating mixture.
[0028] The resin component forms 10%-60% by weight, with particular
preference 25%-50% by weight, of the coating mixture.
[0029] Initiators are used in order to cure the liquid coating. Use
is made of AZO initiators or organic peroxides. Preferred
initiators used are dialkyl peroxides, keto peroxides, peroxy
esters, diacyl peroxides, hydroperoxides and/or peroxy ketals. The
initiator is used in amounts of 0.5% to 5%, with particular
preference 1%-4% with respect to the overall resin composition.
[0030] When using dibenzoyl peroxide as initiator it is preferred
to add a tertiary amine in order to accelerate curing. Preferred
tertiary amines are N,N-dimethylanilines and
N,N-dialkyl-p-toluidines.
[0031] The fraction of the tertiary amines as a proportion of the
overall resin mixture is 0.1%-4%, preferably 0.25%-3%.
[0032] Preferred azo initiators are 2,2-azobis(amidinopropane)
dihydrochloride, 2,2-azobis(2-methylbutyronitrile),
2,2-azobis(2-methylpropanenitrile),
2,2-azobis(2,4-di-methylpentanenitrile), and mixtures thereof.
[0033] A substantial improvement in the adhesion properties of the
intumescent coating on metal surfaces is achieved through the
addition of acid (meth)acrylates or copolymerizable
polyfunctionalized carboxylic acids. The acid (meth)acrylates are
preferably selected from the group of dicarboxylic acids,
particular preference being given to the use of .beta.-CEA.
Copolymerizable polyfunctionalized carboxylic acids that can be
used include all known multiply functionalized carboxylic acids,
selection taking place with particular preference from the group of
itaconic acids, fumaric acids and maleic acids.
[0034] Beta-CEA is the Michael product of acrylic acid and is
always a mixture of:
##STR00001## [0035] beta-carboxyethyl acrylate
[0036] where n=1-20
[0037] The acid (meth)acrylates or copolymerizable
polyfunctionalized carboxylic acids preferably form a part of the
polymeric component of the resin.
[0038] These acid (meth)acrylates or copolymerizable
polyfunctionalized carboxylic acids additionally have a good
dispersing effect on the intumescent constituents used.
[0039] The object has also been achieved by a process for curing
intumescent coatings comprising resin systems according to claim 1.
The process of the invention is characterized in that at least one
ethylenically unsaturated monomer component and at least one
polymeric component comprising one acid (meth)acrylate or
copolymerizable polyfunctionalized carboxylic acids and the
customary intumescent auxiliaries and additives, are polymerized by
means of free radical polymerization.
[0040] The intumescent coating comprises specific substances which
when exposed to heat react with one another and form a foam for
isolation. The coating is composed preferably of 3 components: an
acid source, a carbon source and a gas source.
[0041] On exposure to heat, the resin component begins to melt. At
higher temperatures the acid source is activated and is able to
react with the other constituents of the coating. The acid source
used is, for example, ammonium polyphosphates or polyphosphoric
acids, which react with pentaerythritol (carbon source), for
example, to form polyphosphoric ester. The breakdown of this ester
leads to carbon compounds, which together with foaming agents such
as melamine form the desired foam.
[0042] The intumescent coating ideally comprises at least one acid
source such as ammonium polyphosphate, melamine phosphate,
magnesium sulphate or boric acid, for example.
[0043] The intumescent coating mixture comprises a carbon source,
such as pentaerythritol and dipentaerythritol and mixtures thereof,
for example. Starch and expandable graphite are likewise
suitable.
[0044] The intumescent coating mixture comprises a gas source, such
as melamine, melamine phosphate, melamine borate,
melamine-formaldehyde, melamine cyanurate,
tris(hydroxyethyl)isocyanurate, ammonium polyphosphate or
chlorinated paraffin, for example.
[0045] In addition there may be nucleating agents present.
[0046] These may be, for example, titanium dioxide, zinc oxide,
aluminium oxide, silicon, silicates, heavy metal oxides such as
cerium oxide, lanthanum oxide and zirconium oxide, mica or
loam.
[0047] Further adjuvants (e.g. zinc borate, glass beads, fibre
materials, etc.) may be present in the intumescent coating
mixture.
[0048] The fraction of the intumescent components as a proportion
of the coating mixture is 40%-85%, preferably 50%-75%.
[0049] Thixotropic adjuvants can be used in order to improve the
rheology, in order to make thick coatings possible in one
application step. They are added in amounts of 0%-2%, preferably
0.05%-1%, based on the total amount of the coating.
[0050] It is also possible for wetting adjuvants or dispersion
adjuvants to be added.
[0051] Prior to the application of the coating to the metallic
surface the organic peroxide is added. This initiates the
free-radical reaction in the course of which the liquid coating
cures. Typically the cure time is 30 minutes. It can be varied
through the amount of initiator and accelerator.
[0052] The coating can be applied by means of spraying technology,
brush, roller, spatula or dipping process. As an alternative it is
also possible to use a multi-component spraying system.
[0053] The metal surface is typically cleaned before the coating is
applied, in order to remove processing residues and the like. In
some cases primers are applied as well.
[0054] It is also possible to apply a topcoat, for exposed metal
surfaces, for example. The thickness however, should only be
between 15 .mu.m and 250 .mu.m, in order not to inhibit the
intumescent reaction.
[0055] The outstanding adhesion properties allow the resin system
for intumescent coatings, in accordance with the invention, to be
applied to other surfaces in need of an intumescent coating.
Surfaces of wood, for example, can also be coated.
EXAMPLES
Example 1
[0056] The resin system of the invention is processed using a
[0057] Graco Extreme Mix Plural Component Spray System. This
airless spray system uses 2 pumps, which with an inlet pressure of
0.35 MPa spray the mixture through the nozzle at approximately 19.3
MPa. The nozzle size is approximately 525-675 .mu.m in
diameter.
[0058] Typically 300 .mu.m to 2000 .mu.m are applied per coating
pass. In these experiments, 6 coating passes, each with a thickness
of approximately 1000 .mu.m, were applied to the substrate. The
substrate coated was Swedish standard Sa 21/2% construction
steel.
[0059] Adhesion to the Steel
[0060] The adhesion of the coating to the construction steel was
determined using a PAT (precision adhesion test equipment,
hydraulic adhesion tester) instrument.
[0061] An adhesion of on average 6.9 MPa was measured.
[0062] This figure meets the requirements for a construction steel
coating which can be used industrially.
Comparative Example
[0063] A conventional resin system is processed using a Graco
Extreme Mix Plural Component Spray System. This airless spray
system uses 2 pumps, which with an inlet pressure of 0.35 MPa spray
the mixture through the nozzle at approximately 19.3 MPa. The
nozzle size is approximately 525-675 .mu.m in diameter.
[0064] Typically 300 .mu.m to 2000 .mu.m are applied per coating
pass. In these experiments, 6 coating passes, each with a thickness
of approximately 1000 .mu.m, were applied to the substrate. The
substrate coated was Swedish standard Sa 21/2 construction
steel.
[0065] Adhesion to the Steel
[0066] The adhesion of the coating to the construction steel was
determined using a PAT (precision adhesion test equipment,
hydraulic adhesion tester) instrument.
[0067] An adhesion of on average 1.38 MPa was measured.
[0068] This figure does not meet the requirements for a
construction steel coating which can be used industrially.
* * * * *