TOMMUNE TUTTA LA MICROINTI

US009944816B2

(12) United States Patent (10 ) Patent No.: US 9 ,944 ,816 B2

Peskens et al. (45) Date of Patent : Apr. 17 , 2018
(54 ) CROSSLINKABLE BINDERS FOR SOLVENT 5 ,645,926 A * 7/1997 Horrocks ........... A41D 31/0022
BASED INTUMESCENT COATINGS 428/ 920
6 ,218 ,074 B1 * 4 /2001 Dueber . GO3F 7 /033
(71 ) Applicants :Ronnie Peskens , Allison Park , PA 430 /273 . 1
(US ); Venkateshwarlu Kalsani, 2003/0088045 A1* 5/2003 Haberle . C04B 24 /282
Gibsonia , PA (US ) ; Seiko Fujii Sisco , 528 / 44
Glenshaw , PA (US ); Brianne 2004 /0132910 A1* 7 /2004 Magnet .................. C09D 5 / 185
Hodanich , Allison Park , PA (US ); 525 / 191
Thomas de Boer , Halfweg (NL ) 2006 /0264562 A1 * 11/2006 Duquesne .............. C09D 5 / 185
524 /515
(72 ) Inventors: Ronnie Peskens, Allison Park , PA 2011/0136937 A1* 6/2011 Wierzbicki .... COOK 21/02
523 / 179
(US ); Venkateshwarlu Kalsani, 2012/0121921 A1* 5/2012 Cosyns .............. C04B 224 /2641
Gibsonia , PA (US ); Seiko Fujii Sisco , 428 /522
Glenshaw , PA (US ); Brianne 2014 /0005298 Al * 1/2014 Thewes ............ CO9D 5 /185
Hodanich , Allison Park , PA (US) ; 523 / 179
Thomas de Boer , Halfweg (NL ) 2015/0291810 A1 * 10 /2015 Peskens ................ C09D 5 /185
428/ 463
(73 ) Assignee : PPG Coatings Europe B . V., 2015 /0361301 A1 * 12/ 2015 Egan .................... C09D 133 / 08
Amsterdam (NL ) 524 /35
( * ) Notice : Subject to any disclaimer, the term of this FOREIGN PATENT DOCUMENTS
patent is extended or adjusted under 35 EP 0860742 Al 8 / 1998
U . S .C . 154 (b ) by 59 days. JP 2004012810 A 1 / 2004
WO 199107473 5 / 1991
(21) Appl. No.: 15/170,975 WO
WO
WO 01/60883 A1
WO 2011/009874 A1
8 / 2001
1 / 2011
(22 ) Filed : Jun . 2, 2016 Wo 2014111292 7 /2014

(65 ) Prior Publication Data * cited by examiner

US 2017 /0349776 A1 Dec . 7 , 2017
Primary Examiner — Peter A Salamon
(51) Int. Cl.
C08F 212 / 08 ( 2006 .01) (74 ) Attorney, Agent, or Firm — Diane R . Meyers
C09D 125 /08 ( 2006 .01)
CO9D 5 / 18 ( 2006 .01) (57) ABSTRACT
(52) U . S . CI.
CPC .......... C09D 125 /08 (2013 .01); C08F 212 /08 Self- crosslinkable binder compositions which include a
( 2013 .01 ); CO9D 5 / 185 (2013 .01 ) copolymer obtained by reacting a mixture ofmonomers in
(58 ) Field of Classification Search the presence of an organic solvent, wherein the monomer
None mixture includes a carboxylic acid monomer, a polymeriz
See application file for complete search history . able ethylenically unsaturated monomer, and a crosslinkable
acrylamide monomer. Intumescent coatings containing the
(56) References Cited self-crosslinkable binder, and substrates coated with the
U .S . PATENT DOCUMENTS intumescent coatings are also disclosed.
4 ,304, 701 A 12 / 1981 Das et al.
5 ,618,586 A 4 / 1997 Swarup et al. 9 Claims, No Drawings
 US 9 ,944,816 B2
CROSSLINKABLE BINDERS FOR SOLVENT Throughout this description and in the appended claims,
BASED INTUMESCENT COATINGS use of the singular includes the plural and plural encom
passes singular , unless specifically stated otherwise . For
FIELD OF THE INVENTION example, although reference is made herein to “ a ” polym
5 erizable ethylenically unsaturated carboxylic acid monomer,
The present invention pertains generally to self- crosslink “ a ” polymerizable ethylenically unsaturated monomer , “ a ”
able film - forming compositions , and to use of such compo crosslinkable acrylamide monomer, “ a ” chain transfer agent,
sitions in solvent based intumescent coatings . “ a ” free radical initiator, “ an ” organic solvent, “ an ” acid
source , “ a ” carbon source , and “ a ” gas source , one or more
BACKGROUND OF THE INVENTION 10 of any of these components and / or any other components
described herein can be used .
Intumescent coating compositions may be applied on The word " comprising ” and forms of the word " compris
substrates, such as metal, wood , and other materials , in the ing ” , as used in this description and in the claims, does not
manner of a coating having relatively low film thickness . limit the present invention to exclude any variants or addi
15 tions. Additionally , although the present invention has been
Upon exposure to fire , heat or flames, the intumescent described in terms of “ comprising” , the processes,materials,
coating expands considerably in terms of thickness to pro and coating compositions detailed herein may also be
duce an insulative layer of char and char foam . described as " consisting essentially of” or “ consisting of” .
That is, upon heating , the intumescent coating will pro For example , while certain aspects of the invention have
duce gases and decompose to form a cellular carbonaceous 20 been described in terms of self- crosslinkable binder com
char which is then expanded into foam by release of the positions comprising a copolymer obtained by reacting a
produced gases . The foamed insulating layer of carbon mixture comprising a polymerizable ethylenically unsatu
protects the underlying substrate by reducing the rate of rated carboxylic acid monomer, a polymerizable ethyleni
heating and hence prolongs the time for the substrate to cally unsaturated monomer, and a crosslinkable acrylamide
reach critical failure temperatures . Thus, intumescent coat- 25 monomer, in the presence of an organic solvent, a chain
ings are typically applied to substrates used in the construc transfer agent, and an initiator, a mixture “ consisting essen
tion industry to provide structures and buildings with tially of” or “ consisting of these components is also within
improved fire resistance . the present scope . In this context, " consisting essentially of”
Not only do intumescent coatings provide fire retardancy, means that any additional components will not materially
but they also provide performance characteristics generally 30 affect the molecular weight, acid value , and/or glass transi
expected of a conventional coating, such as fast dry times , tion temperature of the self -crosslinkable binder composi
good durability , and low cost. Incorporating both fire retar - tions, or will not materially affect the intumescent charac
dance and good coating properties in one system is not teristics or shore A hardness of an intumescent coating
straightforward . It would , therefore , be desirable to provide comprising the self- crosslinkable binder compositions .
improved binder compositions which may be useful in 35 Furthermore , the use of “ or” means " and /or” unless
intumescent coatings, and intumescent coatings comprising specifically stated otherwise . As used herein , the term “ poly
these binders which demonstrate both intumescent charac mer” refers to prepolymers, oligomers and both homopoly
teristics and coating properties. mers and copolymers , and the prefix “ poly ” refers to two or
more . “ Including" and like terms means including, but not
SUMMARY 40 limited to . When ranges are given , any endpoints of those
ranges and/or numbers within those ranges can be combined
The present invention is directed to a self-crosslinkable within the scope of the present invention .
binder composition for an intumescent coating, the binder The term “ cure ” , " cured ” or similar terms, as used in
composition comprising a copolymer obtained by reacting a connection with a cured or curable composition, e.g ., a
monomer mixture in the presence of an organic solvent, the 45 “ cured composition ” or “ cured coating" of some specific
monomer mixture comprising ( i) 0 .5 to 10 percentby weight description , means that at least a portion of the film - forming
of a polymerizable ethylenically unsaturated carboxylic acid copolymer or “ binder composition ” that form the coating are
monomer ; ( ii ) 50 to 90 percent by weight of a polymerizable polymerized and/ or crosslinked , or are dried to form a
ethylenically unsaturated monomer different than (i ); and hardened film . Curing or drying reactions to form the
( iii ) 7 to 50 percent by weight of a crosslinkable acrylamide 50 hardened film may be carried out under ambient conditions.
monomer, wherein the percent by weight is based on the By “ ambient conditions ” is meant the condition of surround
total weight of the monomer mixture . The binder composi ings without adjustment of the temperature , humidity or
tion has an acid value of less than 100 mg KOH / g and the pressure . Usually ambient temperature ranges from 60 to
resulting copolymer has a weight average molecular weight 90° F . (15 .6 to 32 .2° C .), such as a typical room temperature,
of greater than 20 ,000 . 55 72° F . (22 .2° C .). Once cured or dried , a film - forming resin
The present invention is also directed to solvent based is stable on exposure to solvents and to moderate heat.
intumescent coatings containing these self -crosslinkable As used herein and in the claims, the term “ linear” refers
binder compositions and substrates coated with the intumes to hydrocarbon and /or polymer chains that are substantially
cent coatings. in a straight line. As used herein and in the claims, the term
60 “ branched ” refers to hydrocarbon and /or polymer chains that
DETAILED DESCRIPTION contain side chains connected or otherwise covalently
bonded to the main chain . As used herein and in the claims,
The present invention provides self-crosslinkable film - the term " self-crosslinkable” refers to crosslinking within
forming compositions useful as binder compositions in the copolymer that does not depend on the presence of other
intumescent coatings , solvent based intumescent coatings 65 monomers .
comprising the binder composition compositions, and sub Other than in any operating examples , or where otherwise
strates coated with the intumescent coatings. indicated , all numbers expressing , for example, quantities of
 US 9, 944,816 B2
ingredients used in the specification and claims are to be and 6 to 12 carbon atoms in any aromatic group (it is
understood as being modified in all instances by the term understood that the alkyl, aralkyl, cycloaliphatic , heterocy
“ about” . Accordingly , unless indicated to the contrary , the clic and aromatic moieties may be substituted by heteroa
numerical parameters set forth in the following specification tom -containing groups such as hydroxyl and acetoxy
and appended claims are approximations that may vary 5 groups ), examples including methyl (methacrylate , ethyl
depending upon the desired properties to be obtained by the meth )acrylate, butyl (methacrylate , tert -butyl (methacry
present invention . At the very least, and not as an attempt to late , cyclohexyl (meth )acrylate, 2 -ethylhexyl (meth )acry
limit the application of the doctrine of equivalents to the late, tetrahydrofurfuryl acrylate, 2 -tetrahydropyranyl acry
scope of the claims, each numerical parameter should at late , benzyl-(meth )acrylate , phenyl (methacrylate ,
least be construed in light of the number of reported sig - 10 4 -acetoxyphenethyl acrylate , 2 -(4 -benzoyl-3 -hydroxyphe
nificant digits and by applying ordinary rounding tech - noxy )ethyl acrylate , benzyl 2 -propylacrylate , isobornyl
niques . (methacrylate and lauryl (meth )acrylate; and acryloyl con
Notwithstanding that the numerical ranges and param taining monomers such as acryloyl chloride and acryloyl
eters setting forth the broad scope of the invention are morpholine.
approximations , the numerical values set forth in the specific 15 The polymerizable ethylenically unsaturated monomer
examples are reported as precisely as possible . Any numeri- (ii) present, in the monomer mixture may comprise styrene,
cal value , however, inherently contains certain errors nec - substituted styrenes, and alkyl, cycloalkyl, or aromatic esters
essarily resulting from the standard variation found in their of (meth )acrylic acid having from 4 to 12 carbon atoms,
respective testing measurements . typically 6 to 12 carbon atoms, in the alkyl, cycloalkyl, or
Unless otherwise indicated , molecular weights are 20 aromatic group such as butyl (meth Jacrylate , cyclohexyl
reported as weight average molecular weights determined by (meth )acrylate, phenyl (meth )acrylate , and any mixture
gel permeation chromatography relative to polystyrene stan - thereof.
dards with the unit of g/mol. The self -crosslinkable binder composition may comprise
Acrylic and methacrylic are designated herein in a sum - 50 to 90 percent by weight of the polymerizable ethyleni
marizingmanner as (methacrylic . Likewise , allyl and meth - 25 cally unsaturated monomer ( ii) , such as 60 to 80 percent by
allyl are designated herein in a summarizing manner as weight, based on the total weight of the monomer mixture .
(meth ) allyl. Suitable crosslinkable acrylamide monomers (iii ) include
The present invention provides a self -crosslinkable binder but are not limited to N -methylolacrylamide , N -methylol
composition for a solvent based intumescent coating, methacrylamide, N - (alkoxymethyl)acrylamides or
wherein the binder composition comprises a copolymer 30 N -( alkoxymethyl)methacrylamides with a C , - to Co- alkyl
obtained by reacting a monomer mixture in the presence of radical, such as N -(isobutoxymethyl) acrylamide ( IBMA ),
an organic solvent. The monomer mixture comprises (i) a N -( isobutoxymethyl) methacrylamide (IBMMA ), N -(n -bu
polymerizable ethylenically unsaturated carboxylic acid toxy -methyl)-acrylamide (NBMA ) and N -(n -butoxy
monomer, ( ii) a polymerizable ethylenically unsaturated methyl)-methacrylamide (NBMMA ), N - phenylacrylamide ,
monomer, and ( iii) a crosslinkable acrylamide monomer. 35 N - (3 -methoxypropyl) acrylamide , N -isopropylmethacryl
The polymerizable ethylenically unsaturated carboxylic amide, N -isopropylacrylamide , 2 -hydroxypropylmethacry
acid monomer (i) may comprise one or more a ,B -monoeth - lamide , N -(hydroxymethyl) acrylamide, N -hydroxyethyl
ylenically unsaturated mono - and dicarboxylic acids ( e. g., acrylamide, N - ethylacrylamide , N - [3 -(dimethylamino )pro
acrylic acid , methacrylic acid , itaconic acid , maleic acid , pyl] methacrylamide , and the like.
fumaric acid , crotonic acid , dimethacrylic acid , ethylacrylic 40 The self -crosslinkable binder composition may comprise
acid , allylacetic acid , vinylacetic acid , mesaconic acid , 7 to 50 percent by weight of the crosslinkable acrylamide
methylenemalonic acid , or citraconic acid , or mixtures of monomers ( iii), such as 10 to 35 percent by weight or 12 to
two or more of these monomers ). In some examples, the 30 percent by weight, based on the total weight of the
polymerizable ethylenically unsaturated carboxylic acid monomer mixture . Amounts which are too low , such as less
monomers useful for preparing the copolymer are selected 45 than 7 percent by weight of the self -crosslinkable binder
from the group consisting of (meth )acrylic acid , itaconic composition , may not provide coatings with sufficient mar
acid , maleic acid , fumaric acid , and mixtures thereof. resistance or hardness, while coatings comprising more than
The self-crosslinkable binder composition may comprise 50 percent by weight of the self-crosslinkable binder com
0 .5 to 10 percent by weight of the polymerizable ethyleni- position may gel during curing and may not provide suffi
cally unsaturated carboxylic acid monomer (i), such as 2 to 50 cient chemical resistance or expansion on heating when
9 percentby weight or 3 to 8 percentby weight, based on the included in an intumescent coating. The term “ gel” may be
total weight of the monomer mixture . According to certain taken to mean that the binder composition has an intrinsic
aspects of the present invention , the acid number of the viscosity which is too high to allow measurement of the
self -crosslinkable binder composition may be less than 100 molecular weight of the copolymer by gel permeation chro
mg KOH / g, such as less than 50 mg KOH / g, or even less 55 matography (i.e ., an essentially infinite molecular weight).
than 20 mg KOH /g . As such , the self-crosslinkable binder The self- crosslinkable binder composition may comprise
composition of the present invention may not need to be a copolymer obtained by reacting a monomer mixture com
neutralized prior to use in a coating such as , for example , an
prising (i) 0 .5 to 10 percent by weight of a polymerizable
intumescent coating . ethylenically unsaturated carboxylic acid monomer, ( ii ) 50
The polymerizable ethylenically unsaturated monomer 60 to 90 percent by weight of a polymerizable ethylenically
( ii ) may comprise vinyl aromatics such as such as styrene, unsaturated monomer different than (i), and ( iii) 7 to 50
alpha-methyl styrene, vinyl toluene, and t- butyl styrene ; percent by weight of a crosslinkable acrylamide monomer,
ethylenically unsaturated aliphatic monomers such as eth each based on the total weight of the monomers in the
ylene , propylene, and 1 , 3 -butadiene; alkyl, aralkyl, cycloa -monomer mixture .
liphatic , heterocyclic , or aromatic esters of (meth )acrylic 65 The copolymer of the self-crosslinkable binder composi
acid having from 1 to 17 carbon atoms in the alkyl group , tion described above can be prepared by free radical initiated
with from 4 to 12 carbon atoms in any cycloaliphatic group addition polymerization of the monomermixture, such as by
 US 9, 944,816 B2
organic solution polymerization techniques. The monomers peroxydicarbonates, peroxyesters, dialkyl peroxides ,
are typically dissolved in an organic solvent or mixture of hydroperoxides , and peroxyketals .
solvents including ketones such as methyl ethyl ketone ; Exemplary azo compounds include at least 4 -4'- azobis (4
esters such as ethyl acetate , butyl acetate, the acetate of cyanovaleric acid ), 1 - 1'-azobiscyclohexanecarbonitrile ,
propylene glycol, and hexyl acetate ; alcohols such as etha - 5 2 - 2'- azobisisobutyronitrile , 2 - 2 -azobis( 2 -methylpropiona
nol and butanol , ethers such as propylene glycol monopro - midine ) dihydrochloride, 2 -2'- azobis ( 2 -methylbutyroni
pyl ether and ethyl -3 - ethoxypropionate ; and hydrocarbon trile ), 2 - 2 '-azobis (propionitrile ), 2 - 2 '-azobis (2 ,4 - dimethyl
solvents including aromatic solvents such as xylene and valeronitrile ), 2 -2'-azobis( valeronitrile ) 2, 2'- azobis [2
AROMATIC 100 or SOLVESSO 100 , a mixture of high methyl-N -( 2 -hydroxyethyl) propionamide ], 4 ,4 '-azobis (4
boiling hydrocarbon solvents available from Exxon Chemi- 10 cyanopentanoic acid ), 2 ,2'-azobis(N ,N '-dimethylene
cal Co . One or more of the monomers of the monomer isobutyramidine), 2 ,2 '- azobis ( 2 -amidinopropane)
mixture may be at least partially soluble in the solvent. dihydrochloride , 2, 2'- azobis (N ,N -dimethylene -isobutyr
In an exemplary organic solution polymerization process , amidine )dihydrochloride and 2 -(carbamoylazo )- isobuty
the solvent is charged to a flask equipped with a thermom - ronitrile .
eter, agitator, condenser and dropping funnel. The dropping 15 While certain exemplary initiator compounds have been
funnel is charged with the monomer mixture, a chain trans - listed , any suitable compound that can initiate polymeriza
fer agent, and one or more initiators . The organic solvent is tion for the monomers of the monomer mixture disclosed
first heated to reflux , usually between 110° C . to 160° C ., herein may be used in the invention. The initiator is typically
and the monomer mixture including the chain transfer agent present in the reaction mixture at about 0 .5 to 8 percent by
and initiator is slowly added to the refluxing solvent, over a 20 weight, such as 0 .5 to 5 percent by weight, based on total
period of about 1 to 5 hours. Adding the monomers too weight of all components employed to prepare the copoly
quickly may cause poor conversion or a high and rapid mer.
exotherm , which is a safety hazard . Adding the monomers Thus, the self -crosslinkable binder composition com
too slowly, such as over a period greater than 5 hours, may prises a copolymer obtained by reacting a monomer mixture
yield a copolymer with an undesirably high molecular 25 (I) comprising: (i ) a polymerizable ethylenically unsaturated
weight. carboxylic acid monomer , (ii) a polymerizable ethylenically
Additional charges of the initiator may be added over the unsaturated monomer, and (iii ) a crosslinkable acrylamide
course of several hours while maintaining reflux tempera - monomer, in the presence of (II ) a chain transfer agent, (III)
ture. After addition is completed , the contents of the flask a free radical initiator, and ( IV ) an organic solvent.
may be held at reflux temperature for several additional 30 As used herein and in the claims, the term “ binder
hours to ensure conversion ofmonomers to copolymer. The composition” refers to a composition comprising at least one
productmay then be cooled and diluted to a desired solids film - forming component, such as a polymer or copolymer.
content using additional solvent. As used herein and in the claims, the term " copolymer”
As described , the monomer mixture may be reacted in the refers to polymers that are the reaction product of two or
presence of a chain transfer agent and one or more initiators . 35 more reactants , such as two or more different monomers .
Chain transfer agents are compounds which are generally Thus , in the present invention , the self-crosslinkable binder
used in the manufacture of acrylic addition polymers to composition generally comprises the copolymer which is the
control their molecular weight. Such substances are added to reaction product of the monomer mixture ( 1) listed above ,
the monomer mixture during polymerization and can be reacted in the presence of the chain transfer agent ( II), the
considered part of the total amount of monomers used in 40 free radical initiator (III ), and the organic solvent ( IV ) , and
forming the addition polymers. The chain transfer agent of additionally , any unreacted monomers , chain transfer agent,
the present invention may comprise mercaptans, ketones, free radical initiator, and organic solvent.
and chlorohydrocarbons . The polymerizable ethylenically unsaturated carboxylic
Exemplary chain transfer agents include alkylmercaptans acid monomer (I) (i) is typically included in amounts of from
which are soluble in the monomer mixture , such as octyl 45 0 .5 to 10 percent by weight, such as from 0 .5 to 5 percent
mercaptan , dodecylmercaptan , pentaerythritol tetra (3 -mer - by weight, based on the total weight of all components
captopropionate ), tertiary -dodecyl mercaptan ; and ketones employed to prepare the copolymer. The polymerizable
such as methyl ethyl ketone . According to certain aspect of ethylenically unsaturated monomer (I) ( ii ) is typically
the present invention, the chain transfer agent may be included in amounts from 20 to 80 percent by weight, such
tertiary -dodecylmercaptan , as it results in a high conversion 50 as from 20 to 60 percent by weight, based on the totalweight
of monomer to polymeric product. The chain transfer agent of all components employed to prepare the copolymer. The
may be included in the present invention at up to 5 percent crosslinkable acrylamide monomer ( 1) ( iii) is typically
by weight, such as between 0 . 1 and 5 percent by weight, or included in amounts of from 5 to 50 percent by weight, such
even between 0 .1 and 1 percent by weight, based on the total as from 5 to 30 percent by weight, based on the totalweight
weight of all components employed to prepare the copoly - 55 of all components employed to prepare the copolymer. The
mer. chain transfer agent ( II ) is typically included in amounts of
The initiator of the present invention typically includes a from 0 .1 to 5 percent by weight, such as 0 .1 to 1 percent by
thermal free radical initiator and optionally one or more weight, based on the total weight of all components
solvents , such as those described above for use in the employed to prepare the copolymer. The free radical initiator
self- crosslinkable binder composition . Suitable thermal free 60 (III ) is typically included in amount of from 0 . 5 to 8 percent
radical initiators include , but are not limited to , peroxide by weight, such as from 0 .5 to 5 percent by weight, based on
compounds, azo compounds, persulfate compounds , and the total weight of all components employed to prepare the
mixtures thereof. copolymer. The solventmay be included in amounts of up to
Examplary peroxide compounds include at leasthydrogen 70 percent by weight, such as up to 50 percent by weight,
peroxide ,methyl ethyl ketone peroxides ,benzoyl peroxides , 65 based on the total weight of all components employed to
ditertbutyl peroxides, ditertamyl peroxides , dicumyl perox - prepare the copolymer. The total percent by weight for all of
ides, diacyl peroxides, decanoyl peroxide, lauroyl peroxide, the components employed to prepare the copolymer of the
 US 9 ,944,816 B2
self-crosslinkable binder composition (i.e ., (1)(i), (I)( ii), ture of the polymer. The alpha parameter indicates the
( I)( iii), ( II ), ( III), and ( IV ) combined ) will in most cases add degree of branching and can be determined as described by
to 100 percent. Paillet et al., Journal of Polymer Science Part A : Polymer
The copolymer of the self-crosslinkable binder composi Chemistry , 2012 , 50 , 2967- 2979 , incorporated by reference
tion of the present invention may alternatively be prepared 5 herein . Random linear coil polymers typically have an alpha
in a pressurized tank by a continuous polymerization pro - parameter of between 0 .5 and 0 .8 , while highly branched
cess, such as that described in U .S . Pat. No. 7, 323, 529, polymers have an alpha parameter of less than 0 .5 .
incorporated herein by reference in its entirety . The monomer mixture described herein , upon polymer
The conversion (i.e ., the chemical transformation of ization , may form a copolymer that is linear or non
monomers to copolymers ) can vary based on the process 10 branched . That is , the inventive copolymers of the present
parameters employed and the characteristics desired (mo- invention may exhibit an alpha parameter derived from the
lecular weight, copolymer composition , and the like ). In Mark -Houwink equation of greater than 0 .5 . The source
many cases , unreacted monomers can be removed later in (i. e., purity level) and/ or selection of the crosslinkable
the process. The conversion can be , for example , at least acrylamide monomer ( iii ) may drive the degree of cross
50 % , in some cases at least 55 % , in other cases at least 60 % , 15 linking , wherein selection of a very pure mono - functional
in some situations at least 65 % , and in other situations at crosslinkable acrylamide monomer ( iii ) may lead to a linear
least 75 % calculated as the weight percent of copolymer copolymer.
based on the total weight ofmonomers employed . Also , the The present invention also provides an intumescent coat
conversion can be up to 100 % , in some cases up to 99. 9 % , ing composition comprising the self- crosslinkable binder
in other cases up to 99 % , in some situations up to 96 % , in 20 composition described herein , an acid source, a carbon
other situations up to 95 % , and in particular situations up to source , and a gas source . Under the influence of heat,
90 % calculated as the weight percent of copolymer based on typically between 100° C . and 200° C ., the self -crosslink
the total weight ofmonomers employed . The conversion can able binder composition and certain other components of the
be any value or range between any set of values recited intumescent coating may melt and begin to flow . As the
above . 25 temperature increases ( > 200° C .), the acid source , usually by
The copolymer of the self-crosslinkable binder composi decomposition , produces copious amounts of acid which can
tion of the present invention typically has a weight average react with other constituents in the coating. If the acid source
molecular weight (Mw) of at least 20 ,000 , and in some cases is a polyphosphate, polyphosphoric acids are released which
at least 30 , 000 . The copolymer may have a Mw, of up to can react with the carbon source , for example a polyhydric
500 ,000 , typically up to 100 ,000 , and in some cases up to 30 alcohol, to form polyphosphoric acid esters . The decompo
50 ,000 . The My, of the copolymer is selected based on the sition of these esters leads to the formation of carbon
properties that are to be incorporated into the copolymer, compounds, which together with the gas source such as, for
self- crosslinkable binder composition comprising the copo - example a blowing agent, give rise to a carbon foam or char.
lymer, and/ or intumescent coating composition comprising When a coating comprising a copolymer (binder compo
the self - crosslinkable binder composition . The M , of the 35 sition ) heats and begins to burn , the " slumping ” (dripping )
copolymer may vary in any range of values inclusive of of the flaming copolymer can promote progression of the
those stated above . fire . The formation of a stable foam or char layer after
After polymerization , the self-crosslinkable binder com - combustion of a section of the coating, as described above,
position often has a solids content of over 30 percent by may protect the underlying structure as it creates a barrier to
weight, such as over 50 percent by weight, based on the total 40 further ignition , and reduces the rate of heating of the
weight of the copolymer and organic solvents in the self- underlying structure . As such , a binder composition thatmay
crosslinkable binder composition . Excess solvents may be not melt or slump would improve char formation , thus
removed from the reaction mixture under reduced pressure improving the intumescent characteristics of the coating and
to yield a product with a solids content such as , for example , further protecting the underlying structure .
at least 50 percent by weight solids. Alternately , the self- 45 The self -crosslinkable binder composition of the present
crosslinkable binder composition may be mixed with a invention is observed to have improved intumescent char
solvent, such as any of those disclosed herein , to a final acteristics during fire performance tests (see Table 3 in the
solids content of 30 percent by weight or greater, such as 50 Examples section below ) . Specifically, char slumping is
percent by weight, based on the total weight of the self- significantly improved for the self- crosslinkable binder
crosslinkable binder composition . 50 composition comprising all three monomer components .
The copolymers prepared by the techniques described The comparative data in Table 3 shows that the combined
above may be used in solvent based film - forming compo effect of the three monomers : (i) a polymerizable ethyleni
sitions ; that is, film - forming compositions containing less cally unsaturated carboxylic acid monomer, (ii ) a polymer
than about 5 % by weightwater, based on total weight of the izable ethylenically unsaturated monomer, and (iii) a cross
film - forming composition . 55 linkable acrylamide monomer, gives the most desirable
The monomer mixture described herein , upon polymer - properties. Only when all three monomers are present does
ization , may form a copolymer having a relatively high the coating develop good fire performance, hardness, mois
degree ofbranching . That is , the inventive copolymers of the ture resistance and char properties.
present invention may exhibit an alpha parameter derived Without wishing to be bound by a specific theory , the
from the Mark -Houwink equation of less than 0 .50 , such as 60 present invention is believed to involve additional crosslink
between 0 .4 and 0 .5 . The Mark -Houwink relationship i ng reactions of the crosslinkable acrylamide with itself
between molar mass (M ) and intrinsic viscosity (n ) is (self-crosslinking) upon exposure to heat, such as during a
described by EQ . 1 : fire event. In addition , the release of acid from the acid
source of the coating during theheating processmay further
[n ]= K•M EQQ. 1. 65 catalyze self-crosslinking reactions of the crosslinkable
where K and a (alpha parameter) are empirically deter acrylamide . This additional crosslinking may result in an
mined constants which provide information about the struc increased viscosity that reduces the char slumping and
 US 9, 944,816 B2
10
increases the char density during a fire test (as reported in 6 to 10 percent by weight, based on the total weight of the
Table 3 ). Reduced slumping may provide additional time for intumescent coating composition .
the gases produced on heating (i. e ., gases produced by The solvent may be an organic solvent. Exemplary
thermal decomposition of the gas source ) to foam the organic solvents include aromatic solvents such as toluene ,
coating and produce a stable char. 5 xylene, ketones (acetone, MIBK , MAK , etc . ), ethyl acetate
The intumescent coating compositions of the present and butyl acetate , high boiling aromatic solvents and aro
invention contain an acid source , examples of which include matic solvent blends derived from petroleum such as those
phytate derivatives, ammonium polyphosphate , melamine available from Exxon Mobil Corporation as AROMATIC
phosphate , magnesium sulphate, ammonium pentaborate , 100 or SOLVESSO 100 . The solvent,which is separate from
zinc borate, and boric acid . The acid source is typically 10 any solvent provided by the self-crosslinkable binder com
included in the intumescent coating at from 5 to 40 percent position , may be included in the intumescent coating at from
by weight, such as 10 to 35 percent by weight, or 20 to 30 2 to 40 percent by weight, such as 5 to 25 percent by weight,
percent by weight, based on the total weight of the intumes or even 10 to 20 percent by weight, based on the totalweight
cent coating composition . of the intumescent coating composition.
Particularly suitable as an acid source is ammonium 15 Certain optional components may additionally be
polyphosphate , often abbreviated “ APP ” , because it has a included , such as an inorganic nucleating agent, an inorganic
high phosphorus content and because it yields phosphoric filler, a rheology modifier, a flame retardant, a char rein
acid at temperatures below the decomposition temperatures forcer, and/ or a liquid carrier.
of the carbon and gas sources described below , and yet Although not an essential ingredient in intumescent reac
above the normal temperatures used for processing the 20 tions, inorganic “ nucleating" agents are often included since
intumescent composition . The ammonium polyphosphates they provide sites for the intumescent char to form , and
are polymeric phosphates, having P40 - P linkages, which improve the thermal resistance properties and stability of the
may be represented by the formula : Hn- m + 2 (NH4)mP. O3m + 1) intumescent char during a fire . Thus , the intumescent coat
wherein the average value of n is at least about 10 , the ing compositions of the present invention may contain a
average value of m is a number up to n + 2 , and the ratio m / n 25 nucleating agent, examples of which include certain pig
is in the range of from about 0 .7 to about 1 .2 . The values of ments , such as titanium dioxide, zinc oxide , aluminium
n and m for any particular compound will be positive oxide , micaceous iron oxide, carbon black , and other inor
integers, while the average values of n and m for a mixture ganic compounds including silica , silicates, heavy metal
of compounds constituting the ammonium polyphosphate oxides such as cerium oxide, lanthanum oxide and zirco
may each individually be a positive integer or a positive 30 nium oxide, calcium carbonite , talcum , wollastonite , china
number which is not an integer. Particularly useful ammo- clay, mica and bentonite clay. A nucleating agent such as
nium polyphosphates in the intumescent coating composi titanium dioxide, which is also a pigment,may also provide
tions of the present invention include those having values of opacity and / or color to the coating . The nucleating agent is
n > 1000 . typically included in the intumescent coating at from 3 to 20
The intumescent coating compositions of the present 35 percentby weight, such as 5 to 15 percent by weight, or even
invention contain a carbon source which can be a liquid 6 to 10 percent by weight, based on the total weight of the
carbon source , a solid carbon source , or a combination intumescent coating composition .
thereof. Exemplary carbon sources include organic polyhy - Further additives may be optionally included as part of the
droxy- functional compounds, such as the solid carbon intumescent ingredients to aid char formation and to
sources pentaerythritol, dipentaerythritol, and tripentaeryth - 40 strengthen the char and prevent char degradation . Such
ritol. Starch , sugars such as glycerin , and expandable graph - additives include solids such as zinc borate , zinc stannate ,
ite are other exemplary carbon sources . The carbon source is zinc hydroxystannate , glass flake , glass spheres, polymeric
typically included in the intumescent coating composition spheres , fibers ( ceramic , mineral, glass / silica based ) , alu
from 0 . 1 to 20 percent by weight, such as 3 to 15 percent by minium hydroxide , antimony oxide , boron phosphate ,
weight, or even 8 to 12 percent by weight, based on the total 45 fumed silica . Particularly suitable fibers include engineered
weight of the intumescent coating composition . mineral fibers that are 100 to 500 microns in length . Such
The intumescent coating compositions of the present additives may be included in the intumescent coating at from
invention contain a compound capable of releasing gas upon 1 to 5 percent by weight, based on the total weight of the
exposure to heat. Suitable gas sources are those which intumescent coating composition .
decompose, or are activated , above 200° C ., for example in 50 Further , rheology modifiers , such as a thixotrope may be
the range 280 to 390° C . Suitable gas sources are generally included in the intumescent coating composition . Suitable
nitrogen containing compounds such as melamine, thixotropic additives include organically modified inorganic
melamine salts , melamine derivatives, urea , dicyandiamide, clays such as bentonite clays , hectorite clays or attapulgite
guanidine , and cyanurates . Specific additional examples clays , organic wax thixotropes based on castor oil and castor
include glycine, melamine phosphate , melamine borate , 55 oil derivatives, and fumed silica .
melamine formaldehyde, melamine cyanurate , tris -(hy - To improve or facilitate dispersion of the intumescent
droxyethyl) isocyanurate (THEIC ) , or chlorinated paraffin . ingredients and also to reduce the overall viscosity of the
The gas source is typically included in the intumescent intumescent coating , it may be desired to incorporate wet
coating at from 3 to 20 percent by weight, such as 3 to 15 ting /dispersion additives. Such additives are usually liquid
percent by weight, or even 8 to 12 percent by weight, based 60 in form and can be supplied either containing a solvent or
on the total weight of the intumescent coating composition . can be solvent free .
The intumescent coating composition may further com The self-crosslinkable binder composition of the present
prise a pigment and /or a solvent which is separate from any invention may also provide improved dispersion of the
solvent provided by the self- crosslinkable binder composi- pigment and various other components of the intumescent
tion . A pigment such as, for example , titanium dioxide, is 65 coating disclosed herein . That is , certain of the unreacted
typically included in the intumescent coating at from 3 to 20 monomers such as, for example , the polymerizable ethyl
percentby weight, such as 5 to 15 percent by weight, or even enically unsaturated carboxylic acid monomer or the cross
 US 9, 944,816 B2
11 12
linkable acrylamide monomer, may assist in dispersing the thickness of the primer may be in the range from 15 microns
pigments (e.g ., titanium dioxide ). The polymerizable ethyl to 250 microns , such as in the range from 25 microns to 100
enically unsaturated carboxylic acid monomer may also microns.
release gases such as carbon dioxide on heating , thus pro A topcoat may be applied to the cured intumescent
viding additional gas for the foaming process . 5 coatings of the present invention , particularly to provide
The intumescent compositions of the present invention
may further comprise a halogenated polymeric resin as a color to exposed steelwork . A topcoat may enhance the
flame retardant and/ or char expansion agent. A particularly durability of the intumescent coating compositions . A clear
suitable flame retardant includes chlorinated paraffin , which sealer may also be suitable . Examples of suitable topcoats
may be included in the composition at from 0 to 15 percent 10 are coatings based on epoxy, polyurethane, alkyd , acrylic ,
by weight, such as 2 to 12 percent by weight, based on the vinyl or chlorinated rubber. The thickness of the topcoat can
total weight of the intumescent coating composition .
Furthermore , the pigment volume concentration (PVC ) vary from 15 microns to 250 microns, such as from 25
may be 30 to 80 percent, such as from 50 to 75 percent, or microns to 75 microns, as too high a thickness of topcoat
even 55 to 70 percent. “ PVC ” , as used herein , is equal to the 15 may inhibit the intumescent reactions.
volumeof pigment compared to the total volume of all solids
in the coating composition . EXAMPLES
The present invention is further drawn to substrates at
least partially coated with an intumescent coating composi
tion as described herein . Substrates to which these compo - 20 The following examples are intended to illustrate the
sitions may be applied include rigid metal substrates, such as invention , and should not be construed as limiting the
ferrous metals, aluminum , aluminum alloys , copper, and invention in any way. Percentages of components are by
other metals or alloys. Exemplary ferrous metal substrates weight unless otherwise indicated .
useful in the practice of the present invention include iron ,
steel, and alloys thereof . 25
25
Example A
Steel sections requiring fire protection are normally blast
cleaned prior to the application of an intumescent coating to
remove millscale and other deposits that may lead to pre A self- crosslinkable binder composition according to the
mature failure of the intumescent coating , either on pro present invention (binder A ) was prepared using the ingre
longed atmospheric exposure or during a fire situation . In dients and amounts listed in Table 1.
TABLE 1
INGREDIENTS Ingredient Function Parts by Weight (grams)
Charge 1 Xylene Organic solvent Binder Binder Binder
A B* C*
28.90 28 . 90 28.90
Charge 2 Methacrylic acid (I) Monomers 22..43
43 - 22..43
43
(i) Carboxylic acid monomer
Styrene ( ii ) Polymerizable 36 .47 36 .47 36 .47
ethylenically
unsaturated monomer
nBMA (iii ) Crosslinkable 16 . 91 16 .91 -
acrylamide monomer
Tertiary dodecyl (II) Chain transfer agent 0 .54 0 .54 0 .54
mercaptan
Xylene solvent 0 .72 0.72 0 .72
Charge 2a 8 . 2 % Charge 2 added to start or seed the reaction
Charge 3 Xylene solvent 5. 89 5 .89 5 .89
t-butyl peroxyacetate (III) Free radical initiator 1. 50 1.50 1 . 50
Charge 3a 8 .6 % Charge 3 added to start or seed the reaction
Charge 4 Xylene solvent 1 . 88 1 . 88 1 .88
t-butyl peroxyacetate (III) Free radical initiator 0 . 33 0 .33 0 . 33
Charge 5 Xylene solvent 1 . 88 1 .88 1. 88
t-butyl peroxyacetate (III) Free radical initiator 0 .33 0 . 33 0 .33
Charge 6 Xylene solvent 1. 88 1 .88 1. 88
t-butyl peroxyacetate (III) Free radical initiator 0 . 33 0 .33 0 .33
nBMA — n -butoxymethyl acrylamide (57.5 % solution ) sourced from Dorf Ketal Chemicals;
t-butyl peroxyacetatc - 50 % solution and Tertiary dodecylmercaptan were sourced from Arkema Inc;
Xylene and Styrene were sourced from Shell Chemical;
Methacrylic acid sourced from Evonik Ind .
*Comparative Examples

order to prevent deterioration of the blast cleaned surface , 60 Charge 1 was added to a 1-liter, four-neck round bottom
particularly where there is a delay in applying the intumes- glass flask equipped with a motor driven stainless steel stir
cent coating, it is normal practice to apply a primer coating: blade, a water -cooled condenser, a nitrogen inlet , and a
This is often the case when the intumescent coating is heating mantle with a thermometer connected through a
applied on site . temperature feedback control device . The content of the
Examples of suitable primers are coatings based on epoxy , 65 flask was refluxed at 140° C . under nitrogen . The charge 2a
modified epoxy (such as modified with polyvinyl butyral), and 3a were added to the flask at an equal rate over 5 minutes
polyurethane, acrylic, vinyl and chlorinated rubber. The and held until reflux temperatures are established . These
 US 9 ,944,816 B2
13 14
charges represent a percentage of charges 2 and 3 (charge 2a TABLE 2 -continued
is 8 .2 % of charge 2 , and charge 3a is 8 .6 % of charge 3 )
which are added to start or seed the reaction . The remaining PARTS BY WEIGHT ( g )
amount of Charge 2 and 3 were fed to the flask over four Ingredient Coating Coating Coating
hours , and then Charge 4 was added over 3 hours under 5 INGREDIENTS Function 1 2* 3*
reflux conditions . Charges 5 and 6 were added over 30 Ammonium Acid source 25 . 4 25 . 4 25 . 4
minutes each with a 30 minute hold in between . After all the Polyphosphate
charges were complete , the flask was held for an additional Melamine
Xylene
Gas source
Organic solvent
7 .6
17 . 7
7 .6
17 . 7
7.6
17 . 7
1.5 hours at reflux temperatures and then theheat was turned TIO Pigment
off. The entire content was cooled to < 40° C ., poured out and 10 China
6 .4 6 .4 6 .4
Clay E Inorganic filler 4 .0 4 .0 4 .0
a sample was placed in a 120° F. (49° C .) hot room for four Chlorinated paraffin Flame retardant 8 .5 8 .5
weeks, and the sample remained liquid . Fumed silica Rheology modifier 0 .5 0 .5 0 .5
The resin had weight average molecular weight, Hydrogenated
castor oil
Rheology modifier 0 . 8 0 .8 0 .8
M .. = 37807 (determined by gel permeation chromatography 15 Binder A : a 52 % styrene-methacrylic acid -nBMA binder solution in xylene according to
using polystyrene as a standard ), an acid value of 14 .7 the present invention ;
(ASTM D1639 ), a gardner bubble viscosity Z according to Binder B : a 52 % styrene- nBMA binder solution in xylene (comparative); and
ASTM -D1725 (corresponding to ~ 22.7 poise ), and 52 % Binder C : a 52 % styrene-methacrylic acid binder solution in xylene ( comparative ).
* Comparative Examples
solids (110° C ./ 1 h solids according to ASTM -2369 ).
Comparative binder compositions B and C were formu - 20 The char expansion factor was determined by measuring
lated as described above except that binder composition B the volume increase of the char on the steel at 8 points
lacks monomer
lacks monomer ((ii )), the
the polymerizable
polymerizable ethylenically
ethylenically unsatu
unsatu- equally spread over the surface . Char cracking and slumping
rated carboxylic acid monomer, and binder composition C were visually inspected . The char was removed from the
steel and cut to assess adhesion and density of the air
lacksmonomer (iii ), the crosslinkable acrylamide monomer. s pockets . All physical properties were rated on a scale of 1 to
Example B 5 , 1 being the worst and 5 being the best.
The comparative data in Table 3 shows that binder com
The binder composition A (acrylic resin binder ) from POS positions having the combined effect of the threemonomers:
Example A was used to prepare an intumescent coating (i) a polymerizable ethylenically unsaturated carboxylic acid
(inventive coating 1: Table 2 ), which is compared to com - 30 monomer, ( 11 ) a polymerizable ethylenically unsaturated
monomer different from (i), and (iii ) a crosslinkable acryl
parative coatings 2 and 3 formulated with binder composi amidemonomer, produce coatings having themostdesirable
tions B and C , respectively ( Table 3).
The coating formulations were prepared with a Disper properties
is
. For example , the char slumping and char density
significantly improved for the self-crosslinkable binder
mat- type dissolver equipped with a heavy duty stainless composition comprising all three monomer components .
steel dispersion impeller. The binder compositions were 35 Additional
con crosslinking reactions of the crosslinkable acry
used as grind vehicle for the solid materials. The solid
materials were slowly added at low peripheral speed to lamide with itself ( self-crosslinking ) upon exposure to heat,
such as during a fire event, may lead to an increased
maintain temperature < 30° C . After all solids were added , a viscosity that reduces the char slumping and increases the
homogeneous dispersion was obtained by high speed mixing char density during a fire test . The reduced slumping may
to 45° C . 40
The coatings were stored for 24 hours at 20° C . prior to provide additional time for the gases produced on heating
(i.e., gases produced by thermal decomposition of the gas
application . The coatings were applied on W6x16 mild steel source
H -shaped columns and 7x3x3/ 16 inch mild steel panels. Two evident) into foamTable
the coating and produce a stable char. Also
3 is the increased time for the coated steel
coats of 500 microns dry film thickness each were applied
is to reach the critical
with a 48 hour recoat interval at 20° C . The coating was 45 performance test) . It took failure temperature of 620° C . (fire
applied with a SATAJET 1000B air assisted spray gun using over 50 minutes for the inventive
a 2.0 mm nozzle at 3 bar inlet pressure . The samples were (without the crosslinkable ,acrylamide
coating 1 to reach 620° C . while the comparative coating 3
monomer ) was found
dried for 1 week at ambient conditions followed by 1 week to reach 620° C . at only 36 minutes . The comparative
at 40° C . Final film thickness of each coating was measured socoating
with an Elcometer 456 . The H -columns were fire tested in 50 similar 3time
(without the carboxylic acid monomer ) showed a
to the critical temperature as the inventive
accordance with EN13381 - 8 . The test was stopped when a coating , but had 100 % expansion loss on exposure to
steel temperature of 620° C . was reached . The steel panels humidity and showed poor results for char cracking, slump
were exposed to 100 % humidity condensation at 40° C . and
a 45 degree angle for 48 hours . The panels were dried 24 ing, adhesion , and density .
hours before being burnt with a propane torch operating at 55
2 bar for 3 minutes . TABLE 3
Coating Coating Coating

.
TABLE 2 1 2* 3*
PARTS BY WEIGHT (g ) Fire performance (minutes )
Time for steel substrate to reach
53 51 36
Ingredient Coating Coating Coating 620° C . according to EN13381 -8
INGREDIENTS Function 1 2* 3* Pigment Grind (microns )
ASTM D1210 125
125 125
125 135
B*
C*
Binder
21.5 21.5
21. 5
21. 5
— 21.5
Nail hardness after 48 hours
ambient dry *
65 Expansion loss after 48 hours 100 %
3
40 %%
40
1
100 %
a

35 %
Pentaerythritol Carbon source 7 .6 7.6 7.6 humidity exposure at 40° C .
 US 9, 944 ,816 B2
15
TABLE 3 -continued
16
TABLE 5 - continued
Coating Coating Coating relative Mw absolute Mw Difference
1 3* (via conventional GPC ) (via TD -GPC ) factor
Char Expansion Factor 353 5 Binder F 75 ,716 184 ,400 2.4
Char Cracking *
Char Slumping *
Char Adhesion *
#Ntm
Binder G
Binder H *
33 ,721
15 ,929
67 ,740
15 ,000 ONog
Char Density * Binders E , F , and G : a 52 % styrene-methacrylic acid -NBMA binder solution in xylene
according to the present invention ;
Binder D : Pliolite AC80 - a styrene acrylic binder commercially available from Omnova
* Scale 1 - 5 , 1 being the worst; 5 being the best result 10 Solutions , and
Binder H : a 52 % styrene-methacrylic acid binder solution in xylene.
* Comparative Examples

Example C The commercially available binder composition D has an

alpha parameter of 0 .690. While this value cannot be directly
Binder composition samples comprising varied formula positions Eto, the
15 compared inventive binder composition (Binder com
F and G ) due to the differences in monomer
tions of the monomer mixture (Binder compositions E , F , composition , an alpha parameter of greater than 0 .5 , and the
and G ) were compared to a binder composition formulated similarity between the relative Mw and the absolute Mw
without the crosslinkable acrylamide (Binder composition ( see Table 5 ) suggest that the Binder composition D is a
H ) and a commercially available styrene acrylic binder 30 linear polymer. Thus, the binder composition without the
composition (Binder composition D ). Samples of each crosslinkable acrylamidemonomer (Binder composition H ),
binder composition as listed in Table 4 were submitted for which shows an alpha parameter of 0 .622 , is also likely to
the GPC -triple detector ( TD -GPC ) method to determine the be of
a linear polymer . When compared to the alpha parameters
the binder compositions formed with the crosslinkable
absolute molarmass distribution and branching . Chromato acrylamide
grams of the three detectors, multi-angle laser light scatter- 25 which showmonomer
an
(Binder compositions E , F , and G ) ,
average alpha parameter of 0 .449, it is
ing (MALS)/ refractometer (RI)/ viscometer (VIS ), were apparent that the inventive binder compositions of the
overlaid and absolute Mw values were generated . The present invention are highly branched . This data supports the
relationship between intrinsic viscosity or molecular size to hypothesis that the crosslinkable acrylamide monomer con
the molecular weight of a polymer is expressed by the tributes to branching in these binder compositions .
Mark -Houwink equation (EQ . 1 ). Branched polymers are 30
generally smaller in size and are denser at any given Example D
molecular weight compared to linear polymers so the intrin
sic viscosity will be lower. Thus , a declined slope of a The copolymer binder A (self-crosslinkable binder ) from
Mark -Houwink plot correlates to a lowerEven alphathough
parameter Example A was used to prepare an intumescent coating
and an increased degree of branching. Even though the 3535 ((inventive
the !cially coating 4 ; Table 6 ), and is compared a commer
n available
degree of polymer branching can be measured only when the coating 5 ; Table styrene 6 ) .
acrylic resin binder (comparative
Testing results are shown in Table 7 .
same polymer with a linear structure is available or its
Mark -Houwink parameters are known, the refractive index
increment (dn /dc ; Table 5 ) values are relatively close among TABLE 6
the samples, which indicates that the chemical compositions 40 Parts By Weight ( g )
are similar and a relative comparison can be made of their
alpha parameters ( Table 4 ). INGREDIENT Ingredient Function Coating 4 Coating 5 *
A Binder 21. 5
TABLE 4 D 11 . 2
Pentaerythritol Carbon source 8 .6 8. 4
Percent by Weight Ammonium Polyphosphate Acid source 26 . 4 26 . 1
(based on total monomers ) Melamine Gas source 8.6 8 .4
Xylene Organic solvent 17. 7 28 .0
Monomer Monomer Monomer dn/dc alpha TiO2 Pigment 6 .4 6 .4
Binder (ii) (iii ) (ml/ g ) parameter China Clay E Inorganic filler 1 .0 2 .0
50 Chlorinated paraffin Flame retardant 8 .5 8.5
Binder D *
Binder E
Binder F
Binder G
Binder H *
Ilon
10
7.5
15
79
80
90
20
19
12 . 5
0 .1380
0 . 1662
0 . 1663
0 .1718
0 .1925
0 .690
0 .433
0 . 451
0 . 462
0 .622
Fumed silica
Hydrogenated castor oil
Rheology modifier
Rheology modifier
0 .5
0.8
0 .5
0 .5
Binder A : a 52 % styrene-methacrylic acid -NBMA binder solution in xylene according to
the present invention ;
Binder D : Pliolite AC80 - a styrene acrylic binder commercially available from Omnova
Binders E , F , and G : a 52 % styrene-methacrylic acid -NBMA binder solution in xylene Solutions.
* Comparative Example
according to the present invention ;
Binder D : Pliolite AC80 - a styrene acrylic binder commercially available from Omnova
Solutions, and
Binder H : a 52 % styrene-methacrylic acid binder solution in xylene .
The formulations were prepared as indicated above in
* Comparative Examples Example B for coatings 1 , 2 and 3 . The coatings were stored
for 24 hours at 20° C . prior to application . The coatings were
60 applied on mild steel 3 ft . IPE 400 beams. Three coats of
TABLE 5 1000 microns dry film thickness each were applied with a 24
hour recoat interval at 20° C . The coating was applied with
relative Mw absolute Mw Difference a 66 :1 pneumatic airless spray pump, operating at 200 bar
(via conventional GPC ) (via TD -GPC ) factor pressure using 4 . 19 inch and 5 . 19 inch nozzles. The samples
Binder D*
Binder D *
Binder E 70.000
70, 000
32,253 39.750
79 ,750
55, 900 1.
1 .1
1.7
65 were dried for 1 week at ambient conditions followed by 1
week at 40° C . Final film thickness of coating wasmeasured
before fire testing , as performed in accordance with
 US 9 ,944,816 B2
17 18
EN13381-8 . The test was stopped when a steel temperature TABLE 8
of 620° C . was reached . The dry -to -touch times were mea
sured in accordance with ASTM D1640 for 1000 micron wet Shore A Hardness * *
coatings . Ambient 40°C
The char expansion factor was determined by measuring 5 Time (hours) Coating 4 Coating 5 * Coating 4 Coating 5 *
the volume increase of the char on the steel beam at 20
points equally spread over its surface. Char cracking and 59 93
slumping were visually inspected . The char was removed
23
63
a
from the steel and cut to assess adhesion and density of the 10
air pockets . All physical properties were rated on a scale of
1 to 5 , 1 being the worst and 5 being the best .
TABLE 7 .
89
113
137
161
* Comparative Example;
S3 65
66
70
74

* * Shore A Hardness measured according to ASTM D2240 ;

ON
Coating 4 comprises Binder A : a 52 % styrene-methacrylic acid -NBMA binder solution in
- 15 xylene according to the present invention ;
Coating 4 Coating 5 * Coating 5 comprises Binder D : Pliolite AC80 - a styrene acrylic binder commercially
available from Omnova Solutions.
Fire performance (minutes ) 130 minutes 119 minutes It will be appreciated that the following embodiments and
Time for steel to reach 620° C . implementations are illustrative and various aspects of the
according to EN13381 -8 20 invention may have applicability beyond the specifically
Expansion loss after 48 hours 40 % 100 %
described contexts . Furthermore , it is to be understood that
100 % humidity exposure at 40° C . these embodiments and implementations are not limited to
Dry to touch according to ASTM 20 minutes 30 minutes the particular components , methodologies , or protocols
D1640 - 1000 microns wet described , as these may vary . The terminology used in the
Overcoat with self interval 4 . 5 hours 6 hours 25 description is for the purpose of illustrating the particular
1000 microns wet versions or embodiments only, and is not intended to limit
Overcoat with topcoat interval 36 hours 48 hours their scope in the present disclosure which will be limited
1000 microns dry only by the appended claims.
Char Expansion Factor
Char Cracking * * + 30 Aspects of the Invention
Char Slumping * * in
3
Char Adhesion * * wn
A Each of the characteristics and examples described above,
Char Density * * + and combinations thereof, may be said to be encompassed
by the present invention , which includes:
* Comparative Example 35 ( 1 ) A self-crosslinkable copolymer obtained by reacting a
* Scale 1- 5 , 1 being the worst; 5 being the best result; monomer mixture in the presence of an organic solvent, the
Coating 4 comprises Binder A : a 52 % styrene-methacrylic acid -NBMA binder solution in monomer mixture comprising: (i) 0 .5 to 10 percent by
xylene according to the present invention ; weight of a polymerizable ethylenically unsaturated carbox
Coating 5 comprises Binder D : Pliolite AC80 - a styrene acrylic binder commercially
available from Omnova Solutions. ylic acid monomer ; ( ii ) 50 to 90 percent by weight of a
40 polymerizable ethylenically unsaturated monomer different
The char expansion factor was determined by measuring from (i ); and (iii) 7 to 50 percent by weight of a crosslinkable
the volume increase of the char on the steel beam at 20 acrylamide monomer, wherein the percent by weight is
points equally spread over its surface. Char cracking and based on the total weight of the monomer mixture , and
slumping were visually inspected . The char was removedne 45 wherein the copolymer has an acid value of less than 100 mg
from the steel and cut to assess adhesion and density of the 43 than 20, 000 ag /weight
KOH / g and average molecular weight of greater
air pockets. All physical properties were rated on a scale of matography relative to determined
mol as by gel permeation chro
polystyrene standards.
1 to 5 , 1 being the worst and 5 being the best. ( 2 ) The copolymer of aspect 1 , wherein the monomer
The comparative data shows that an intumescent coating mixture comprises (i) 3 to 8 percent by weight of the
comprising the self - crosslinkable binder of the present 50 carboxylic acid monomer.
invention ( inventive coating 4 ) performs better than a coat - ( 3 ) The copolymer of aspects 1 or 2 , wherein the mono
ing prepared with a commercially available styrene -acrylic mer mixture comprises ( ii ) 60 to 80 percent by weight of the
resin binder ( comparative coating 5 ) . The time to failure ( fire polymerizable ethylenically unsaturated monomer.
performance ) is improved as well as the char slumping , and (4 ) The copolymer of any of aspects 1 to 3 , wherein the
dry times . That is, the time for the coated steel to reach the 55 monomer mixture comprises (iii) 10 to 35 percent by weight
critical failure temperature of 620° C . ( fire performance test)
was greater than 120 minutes for the inventive coating 4 . (5 ) The copolymer of any of aspects 1 to 4 , wherein the
The coating comprising the inventive binder A (Coating acid monomer (i) comprises an a ,ß -monoethylenically
4 ) also shows a significant improvement in hardnessss devel
devel unsaturated monocarboxylic or dicarboxylic acid , such
opment when compared to coatings formulated with current- 60 (meth )acrylic acid , itaconic acid , maleic acid , fumaric acid ,
or combinations thereof.
styrene acrylic binders ( Coating 5 ), as measured by Shore A (6 ) The copolymer of any of aspects 1 to 5 , wherein the
hardness according to ASTM D2240 . Table 8 shows that an polymerizable ethylenically unsaturated monomer ( ii ) com
intumescent coating comprising the inventive binder A prises styrene, a -methyl styrene, t-butylstyrene, vinyl tolu
achieves a shore A hardness of greater than 90 after 160 65 ene , or a combination thereof.
hours of drying time at ambient conditions, or 25 hours of (7 ) The copolymer of any of aspects 1 to 6 , wherein the
drying time at 40° C . crosslinkable acrylamide monomer ( iii) comprises an
 US 9 ,944,816 B2
19 20
N -(alkoxymethyl)acrylamide with a C - to Co- alkyl radical, of any of aspects 18 to 20 in an intumescent coating
an N -( alkoxymethyl)methacrylamide with a C , - to Co- alkyl providing a substrate with fire retardancy .
radical, or a combination thereof. (22 ) An intumescent coating composition comprising: ( a )
(8 ) The copolymer of aspect 7 , wherein the crosslinkable the self-crosslinkable copolymer according to any of aspects
acrylamide monomer (iii) comprises n - butoxymethyl acry - 5 1 to 17 or the self- crosslinkable binder composition accord
lamide . ing to any of aspects 18 to 20 ; (b ) an acid source ; (c ) a
(9 ) The copolymer of any of aspects 1 to 8 having a carbon source ; and ( d) a gas source .
ca ( 23 ) The intumescent coating composition of aspect 22 ,
weight average molecular weight of greater than 30 ,000 comprising : ( a ) 15 to 30 weight percent of the self-cross
g /mol. 10 linkable binder composition ; (b ) 5 to 40 weight percent of
(10 ) The copolymer of any of aspects 1 to 9 having a the acid source ; (c ) 0 . 1 to 20 weight percent of the carbon
weight average molecular weight of up to 500, 000 g /mol source ; and (d ) 3 to 20 weight percent of the gas source ,
such as up to 100 ,000 g /mol or up to 50 , 000 g /mol. wherein the weight percent is based on the total weight of
(11 ) The copolymer of any of aspects 1 to 10 having an the intumescent coating composition.
acid value of less than 50 mgKOH /g , such as lessS than 2015
20 15 (24 ) The intumescent coating composition of aspects 22
mg KOH / g . or 23 , further comprising (e ) a pigment, such as titanium
(12 ) The copolymer of any of aspects 1 to 11, wherein the dioxide.
copolymer has an alpha parameter derived from the Mark (25 ) The intumescent coating composition of aspect 24 ,
Houwink equation of between 0 .4 and 0 . 50 . wherein the pigment is included at 3 to 20 percentbyweight,
(13) The copolymer of any of aspects 1 to 12 , wherein the 20 based on the total weight of the coating composition .
monomer mixture is reacted in the presence of a chain (26 ) The intumescent coating composition of any of
transfer agent ( II ) and a free radical initiator (III ). aspects 24 or 25 having a pigment volume concentration
(14 ) The copolymer of aspect 13, wherein the chain (PVC ) (volume of pigment compared to the volume of all
transfer agent ( II) comprises a mercaptan such as a mercap - solids ) of 30 to 80 percent, such as from 55 to 70 percent.
tan selected from octyl mercaptan , dodecyl mercaptan , tert- 25 ( 27 ) The intumescent coating composition of any of
dodecyl mercaptan , pentaerythritol tetra ( 3 -mercaptopropi- aspects 22 to 26 , comprising (f) (additional) organic solvent.
onate ), or a combination thereof. (28 ) The intumescent coating composition of aspect 27,
(15 ) The copolymer of aspects 13 or 14 , wherein the free wherein the organic solvent is included at 2 to 40 percent by
radical initiator (III ) comprises 2, 2 - azobisisobutyronitrile , weight, which is in addition to any solvent supplied with the
2 ,2 '-azobis (2 ,4 -dimethylvaleronitrile ), tertiary -butyl perben - 30 binder composition , based on the total weight of the coating
zoate, tertiary -buty ; peracetate, benzoyl peroxide, ditertiary composition .
butyl peroxide , or a combination thereof. ( 29 ) The intumescent coating composition of any of
(16 ) The copolymer of any of aspects 1 to 15 , wherein the aspects 22 to 28 , wherein the acid source is ammonium
monomer mixture is reacted in the presence of an organic polyphosphate .
solvent by a solution polymerization technique . 35 (30 ) The intumescent coating composition of any of
(17 ) The copolymer of aspect 16 which is obtained by aspects 22 to 29, wherein the carbon source comprises an
reacting a monomer mixture (I) comprising : organic polyhydroxy compound .
(i) 0 .5 to 10 percent by weight, such as 0 .5 to 5 percent (31) The intumescent coating composition of any of
by weight, of a polymerizable ethylenically unsaturated aspects 22 to 30 , wherein the gas source is selected from
carboxylic acid monomer, ( ii ) 20 to 80 percent by 40 melamine, melamine salts, melamine derivatives, or com
weight , such as 20 to 60 percent by weight, of a binations thereof.
polymerizable ethylenically unsaturated monomer dif - (32 ) The intumescent coating composition of any of
ferent from (i), and ( iii ) 5 to 50 percent by weight, such aspects 22 to 31, further comprising one or more additives
as 5 to 30 percent by weight, of a crosslinkable acry selected from inorganic nucleating agents, rheology modi
lamide monomer, 45 fiers , inorganic fillers , and flame retardants .
in the presence of ( 33 ) The intumescent coating composition of any of
(II) 0 . 1 to 5 percent by weight, such as 0 . 1 to 1 percent by aspects 22 to 32 , having a solids content by weight of 75 %
weight of a chain transfer agent, or greater, based on the total weight of the coating compo
(III) 0 .5 to 8 percent by weight, such as 0 . 5 to 5 percent sition .
by weight of a free radical initiator, and 50 (34 ) An intumescent coating prepared from the intumes
(IV ) 20 to 70 percent by weight, such as 30 to 50 of an cent coating composition of any of aspects 22 to 33 by
organic solvent, wherein each percent by weight is applying it to a substrate and drying it, wherein the coating
based on the total weight of components ( 1) (i), (1) (ii), achieves a shore A hardness of greater than 90 as measured
(1) ( iii), ( II), (III ), and ( IV ) . according to ASTM D2240 after 160 hours of drying time at
(18 ) A self -crosslinkable binder composition comprising 55 ambient conditions (22 .2° C .) or 25 hours of drying time at
the self- crosslinkable copolymer according to any of aspects 40° C .
1 to 17 and an organic solvent, wherein the copolymer is (35 ) An intumescent coating prepared from the intumes
typically dissolved in the organic solvent. cent coating composition of any of aspects 22 to 33 by
(19) The binder composition of aspect 18 being the direct applying it to a substrate and drying it , wherein the coating
product of the solution polymerization process described in 60 has a time to 620° C . of greater than 50 minutes for a 1000
aspects 16 or 17 . um coating on a W6x16 mild steel H -column, or a time to
( 20 ) The binder composition of aspects 18 or 19 having a 620° C . of greater than 120 minutes for a 3000 um coating
solids content of 30 percent by weight or more , such as 50 on a 3 ft IPE 400 beams, tested according to EN13381 - 8
percent by weight or more, based on the total weight of the after 1 week of drying time at 22° C . followed by 1 week of
binder composition . 65 drying time at 40° C .
(21) Use of the self- crosslinkable copolymer of any of ( 36 ) A substrate coated at least in part with the intumes
aspects 1 to 17 or the self -crosslinkable binder composition cent coating composition of any of aspects 22 to 33 .
 US 9 ,944,816 B2
21 22
What is claimed is: prises at least 30 % solids by weight of the copolymer, based
1 . An intumescent coating composition comprising: on the total weight of the self - crosslinkable binder ( a ) .
(a ) a self-crosslinkable binder composition comprising a 4 . The intumescent coating composition of claim 1 ,
copolymer obtained by reacting a monomer mixture in wherein the polymerizable ethylenically unsaturated carbox
the presence of an organic solvent, thee monomer
monomer mix
mix -. 55 ylic acid monomer (i) comprises (meth ) acrylic acid , itaconic
acid , maleic acid , fumaric acid , or combinations thereof.
ture comprising : 5 . The intumescent coating composition of claim 1 ,
(i) 0 .5 to 10 percent by weight of a polymerizable wherein the polymerizable ethylenically unsaturated mono
ethylenically unsaturated carboxylic acid monomer ; mer ( ii ) comprises styrene, a -methyl styrene, t-butylstyrene ,
( ii ) 50 to 90 percent by weight of a polymerizable vinyl toluene, or a combination thereof.
ethylenically unsaturated monomer different from 10 6 . The intumescent coating composition of claim 1 ,
(i) ; and wherein the crosslinkable acrylamide monomer (iii) com
(iii ) 7 to 50 percent by weight of a crosslinkable prises n - butoxymethyl acrylamide, which is present in an
acrylamide monomer, amount of 10 to 30 percent by weight based on the total
wherein the percent by weight is based on the total 15 weight of the monomer mixture.
weight of the monomer mixture , and wherein the 7 . The intumescent coating composition of claim 1 ,
binder has an acid value of less than 100 mgKOH / g wherein the coating composition , following application to a
and the copolymer has a weight average molecular substrate, achieves a shore A hardness of greater than 90 as
weight of greater than 20 ,000 as determined by gel measured according to ASTM D2240 after 160 hours of
permeation chromatography relative to polystyrene 20 drying time at ambient conditions (22.2° C .) or 25 hours of
drying time at 40° C .
standards with the unit of g /mol ; 8 . The intumescent coating composition of claim 1,
(b ) an acid source ; wherein the coating composition , following application to a
(c ) a carbon source ; and substrate , has a time to 620° C . of greater than 50 minutes
(d ) a gas source . for a 1000 um coating on a W6x16 mild steel H - column
2 . The intumescent coating composition of claim 1 , -251tested according to EN13381-8 .
further comprising (e ) a pigment, an inorganic filler, or an 9 . A substrate coated at least in part with the intumescent
inorganic nucleating agent.
3 . The intumescent coating composition of claim 1, coating composition of claim 1 .
wherein the self -crosslinkable binder composition com * * * * *