U.S. patent application number 14/857215 was filed with the patent office on 2016-01-28 for powder coatings compositions.
This patent application is currently assigned to Blue Cube IP LLC. The applicant listed for this patent is Fabio Aguirre Vargas, Maurice J. Marks. Invention is credited to Fabio Aguirre Vargas, Maurice J. Marks.
Application Number | 20160024336 14/857215 |
Document ID | / |
Family ID | 44627988 |
Filed Date | 2016-01-28 |
United States Patent
Application |
20160024336 |
Kind Code |
A1 |
Marks; Maurice J. ; et
al. |
January 28, 2016 |
POWDER COATINGS COMPOSITIONS
Abstract
A solid epoxy resin powder coarting composition which includes a
divinylarene dioxide resin as one component; and wherein the solid
epoxy resin powder coating composition can be formed by blending or
reacting various other components with the divinylarene dioxide
resin. For example, other components can include other epoxy
resins; phenolic resins; or monomeric and/or polymeric isocyanates.
The powder coating composition or formulation may advantageously
provide, for example, a Fusion Bonded Epoxy coating on a
substrate.
Inventors: |
Marks; Maurice J.; (Lake
Jackson, TX) ; Aguirre Vargas; Fabio; (Lake Jackson,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Marks; Maurice J.
Aguirre Vargas; Fabio |
Lake Jackson
Lake Jackson |
TX
TX |
US
US |
|
|
Assignee: |
Blue Cube IP LLC
Midland
MI
|
Family ID: |
44627988 |
Appl. No.: |
14/857215 |
Filed: |
October 12, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13805022 |
Dec 18, 2012 |
9169417 |
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PCT/US11/41018 |
Jun 20, 2011 |
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14857215 |
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61357644 |
Jun 23, 2010 |
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Current U.S.
Class: |
523/400 |
Current CPC
Class: |
C08G 2650/56 20130101;
B32B 27/38 20130101; C08G 2150/20 20130101; C08G 59/027 20130101;
C09D 163/00 20130101; C09D 165/00 20130101; C08G 59/245 20130101;
C09D 171/00 20130101; C08L 63/00 20130101; C08G 59/1438 20130101;
C08G 18/003 20130101 |
International
Class: |
C09D 163/00 20060101
C09D163/00; C09D 165/00 20060101 C09D165/00 |
Claims
1. A composition comprising a solid curable powder coating
formulation including (i) at least one divinylarene dioxide resin,
wherein the at least one divinylarene dioxide resin eposxy
functional; and (ii) at least one curing component, wherein the at
least one curing component is an epoxy resin, a blend of an epoxy
resin and a curing catalyst, or mixtures thereof.
2-4. (canceled)
5. The composition of claim 1, wherein the divinylarene dioxide
resin, component (i), comprises (a) a blend of a solid epoxy resin
and a divinylarene dioxide compound; or (b) an epoxy oxazolidone
resin prepared from a divinylarene dioxide compound and a monomeric
isocyanate or a polymeric isocyanate; or (c) a phenolic hardener
prepared from a divinylarene dioxide compound and a diphenol.
6. The composition of claim 1, wherein the divinylarene dioxide
compound comprises divinylbenzene dioxide.
7. The composition of claim 5, wherein the solid epoxy resin
comprises an epoxy resin prepared from a stoichiometric excess of
bisphenol A diglycidyl ether and bisphenol A having a Tg of greater
than about 30.degree. C.
8. The composition of claim 5, wherein the epoxy oxazolidone resin
comprises the reaction product of a stoichiometric excess of
divinylbenzene dioxide and a monomeric or polymeric isocyanate
selected from toluene diisocyanate, methylenediphenyl diisocyanate,
xylylene diisocyanate, isophorone diisocyanate, hexamethylene
diisocyanate, and mixtures thereof.
9. The composition of claim 5, wherein the phenolic hardener
comprises the reaction product of divinylbenzene dioxide and a
stoichiometric excess of a diphenol selected from the group
consisting of bisphenol A, tetrabromobisphenol A, bisphenol F,
hydroquinone, resorcinol, biphenol, and mixtures thereof.
10. The composition of claim 1, wherein the catalyst comprises an
imidazole.
11. The composition of claim 1, wherein the curing component
comprises a phenolic resin, or an amine, or an epoxy resin.
12. The composition of claim 1, wherein the curing component
comprises a bisphenol A type phenolic resin or a dicyandiamide.
13. The composition of claim 1, wherein the powder coating
comprises a Fusion Bonded Epoxy coating composition.
14. (canceled)
15. A cured coating comprising the cured composition of claim
1.
16. An article made from the composition of claim 1.
17. The article of claim 16 comprising a coated substrate wherein
the coating on said substrate comprises a solid divinylarene
dioxide resin.
18. A process for preparing a composition comprising admixing (i)
at least one divinylarene dioxide resin; and (ii) at least one
curing component to form a solid curable powder coating
formulation.
19. A process for preparing a cured coating comprising curing the
composition of claim 1 at a temperature of from about 10.degree. C.
to about 300.degree. C.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention is related to solid curable epoxy
resin powder coating compositions derived from divinylarene
dioxides, particularly those derived from divinylbenzene
dioxide.
[0003] 2. Description of Background and Related Art
[0004] Solid powder coating formulations are known in the prior
art. For example, U.S. Pat. No. 2,456,408 describes solid epoxy
resins (SERs) prepared from epoxy resins and diphenols; and
Reinking, J. Poly. Sci. 1963, 7, 2135-2153 describes
poly(hydroxyl-ethers) (PHEs) prepared from epoxy resins and
diphenols. It is known that to be a "solid" powder composition, the
glass transition temperature (Tg) of the composition has to be
greater than about 30.degree. C.
[0005] It would be beneficial to the coating industry to develop
powder coating formulations, powder coating processes, and powder
coated articles based on SERs and phenolic epoxy resins (PERs) that
(i) provide an increase in the Tg of the coating while maintaining
formulation processability; and/or (ii) that maintain the Tg of the
coating while improving formulation processability without
affecting other key properties of the coating such as adhesion and
flexibility.
SUMMARY OF THE INVENTION
[0006] The present invention is directed to a curable powder
coating composition based on a divinylarene dioxide compound, such
as divinylbenzene dioxide (DVBDO). For example, the composition
comprises a solid curable powder coating formulation including (i)
at least one divinylarene dioxide resin; and (ii) at least one
curing component.
[0007] In one embodiment, the composition is a solid curable powder
coating formulation including at least one divinylarene dioxide
resin.
[0008] In another embodiment, the composition is a solid curable
powder coating formulation including at least one divinylarene
dioxide resin, wherein the divinylarene dioxide resin comprises (i)
a blend of a solid epoxy resin and a divinylarene dioxide compound;
or (ii) an epoxy oxazolidone resin prepared from a divinylarene
dioxide compound and a monomeric isocyanate or a polymeric
isocyanate; or (iii) a phenolic hardener prepared from a
divinylarene dioxide compound and a diphenol.
[0009] In still another embodiment, the composition is a solid
curable powder coating formulation including at least one
divinylarene dioxide resin, wherein the divinylarene dioxide resin
comprises a blend of a solid epoxy resin and a divinylarene dioxide
compound.
[0010] In still another embodiment, the composition is a solid
curable powder coating formulation including at least one
divinylarene dioxide resin, wherein the divinylarene dioxide resin
comprises an epoxy oxazolidone resin prepared from a divinylarene
dioxide compound and a monomeric or polymeric isocyanate.
[0011] In yet another embodiment, the composition is a solid
curable powder coating formulation including at least one
divinylarene dioxide resin, wherein the divinylarene dioxide resin
comprises a phenolic hardener prepared from a divinylarene dioxide
compound and a diphenol.
[0012] The above solid curable powder coating formulations can be
advantageously used for providing, for example, a fusion-bonded
epoxy (FBE) coating on a substrate.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The solid curable powder coating composition or formulation
of the present invention generally includes at least one
divinylarene dioxide resin. A "divinylarene dioxide resin" herein
means a mixture containing, as one component either: (i) a
divinylarene dioxide compound or (ii) a reaction product derived
from a divinylarene dioxide compound. For example, a divinylarene
dioxide resin can comprise, but is not limited to: (1) a mixture of
a solid epoxy resin and a divinylarene dioxide compound; (2) a
solid epoxy oxazolidone resin prepared from a divinylarene dioxide
compound and a monomeric and/or polymeric isocyanate; (3) a solid
epoxy resin prepared from a divinylarene dioxide compound; or (4) a
phenolic resin prepared from a divinylarene dioxide compound and a
diphenol.
[0014] In the solid curable powder coating composition of the
present invention, the individual components that make up the
coating composition may be solids or liquids, however, the mixture
of the components are such that the final powder coating
composition of the present invention is a "solid" as defined
herein.
[0015] In a broad embodiment of the present invention, the solid
curable powder coating formulation includes, as one component, the
above-described divinylarene dioxide resin. The divinylarene
dioxide resin used in the present invention is adapted to form a
solid powder coating. In one embodiment, the divinylarene dioxide
resin may be epoxy functional, phenolic functional, or a mixture
thereof. In another embodiment, the divinylarene dioxide resin may
be epoxy functional; or in still another embodiment, the
divinylarene dioxide resin may be phenolic functional.
[0016] The divinylarene dioxide compound useful in forming the
divinylarene dioxide resin of the present invention may comprise,
for example, any substituted or unsubstituted arene nucleus bearing
one, two, or more vinyl groups in any ring position. For example,
the arene portion of the divinylarene dioxide may consist of
benzene, substituted benzenes, (substituted) ring-annulated
benzenes or homologously bonded (substituted) benzenes, or mixtures
thereof. The divinylbenzene portion of the divinylarene dioxide may
be ortho, meta, or para isomers or any mixture thereof. Additional
substituents may consist of H.sub.2O.sub.2-resistant groups
including saturated alkyl, aryl, halogen, nitro, isocyanate, or
RO-- (where R may be a saturated alkyl or aryl). Ring-annulated
benzenes may consist of naphthlalene, tetrahydronaphthalene, and
the like. Homologously bonded (substituted) benzenes may consist of
biphenyl, diphenylether, and the like.
[0017] The divinylarene dioxide compound used for preparing the
composition of the present invention may be illustrated generally
by general chemical Structures I-IV as follows:
##STR00001##
[0018] In the above Structures I, II, III, and IV of the
divinylarene dioxide comonomer of the present invention, each
R.sub.1, R.sub.2, R.sub.3 and R.sub.4 individually may be hydrogen,
an alkyl, cycloalkyl, an aryl or an aralkyl group; or a
H.sub.2O.sub.2-resistant group including for example a halogen, a
nitro, an isocyanate, or an RO group, wherein R may be an alkyl,
aryl or aralkyl; x may be an integer of 0 to 4; y may be an integer
greater than or equal to 2; x+y may be an integer less than or
equal to 6; z may be an integer of 0 to 6; and z+y may be an
integer less than or equal to 8; and Ar is an arene fragment
including for example, 1,3-phenylene group. In addition, R4 can be
a reactive group(s) including epoxide, isocyanate, or any reactive
group and Z can be an integer from 0 to 6 depending on the
substitution pattern.
[0019] In one embodiment, the divinylarene dioxide used in the
present invention may be produced, for example, by the process
described in U.S. Patent Provisional Application Ser. No.
61/141457, filed Dec. 30, 2008, by Marks et at, incorporated herein
by reference. The divinylarene dioxide compositions that are useful
in the present invention are also disclosed in, for example, U.S.
Pat. No. 2,924,580, incorporated herein by reference.
[0020] In another embodiment, the divinylarene dioxide useful in
the present invention may comprise, for example, divinylbenzene
dioxide, divinylnaphthalene dioxide, divinylbiphenyl dioxide,
divinyldiphenylether dioxide, and mixtures thereof.
[0021] In a preferred embodiment of the present invention, the
divinylarene dioxide compound used in the epoxy resin formulation
may be for example divinylbenzene dioxide (DVBDO). Most preferably,
the divinylarene dioxide compound that is useful in the present
invention includes, for example, DVBDO as illustrated by the
following chemical formula of Structure V:
##STR00002##
[0022] The chemical formula of the above DVBDO compound may be as
follows: C.sub.10H.sub.10O.sub.2; the molecular weight of the DVBDO
is about 162.2; and the elemental analysis of the DVBDO is about:
C, 74.06; H, 6.21; and O, 19.73 with an epoxide equivalent weight
of about 81 g/mol.
[0023] Divinylarene dioxides, particularly those derived from
divinylbenzene such as for example DVBDO, are class of diepoxides
which have a relatively low liquid viscosity but a higher rigidity
and crosslink density than conventional epoxy resins.
[0024] Structure VI below illustrates an embodiment of a preferred
chemical structure of the DVBDO useful in the present
invention:
##STR00003##
[0025] Structure VII below illustrates another embodiment of a
preferred chemical structure of the DVBDO useful in the present
invention:
##STR00004##
[0026] When DVBDO is prepared by the processes known in the art, it
is possible to obtain one of three possible isomers: ortho, meta,
and para. Accordingly, the present invention includes a DVBDO
illustrated by any one of the above Structures individually or as a
mixture thereof. Structures VI and VII above show the meta
(1,3-DVBDO) and para isomers of DVBDO, respectively. The ortho
isomer is rare; and usually DVBDO is mostly produced generally in a
range of from about 9:1 to about 1:9 ratio of meta (Structure VI)
to para (Structure VII) isomers. The present invention preferably
includes as one embodiment a range of from about 6:1 to about 1:6
ratio of Structure VI to Structure VII, and in other embodiments
the ratio of Structure VI to Structure VII may be from about 4:1 to
about 1:4 or from about 2:1 to about 1:2.
[0027] In yet another embodiment of the present invention, the
divinylarene dioxide may contain quantities (such as for example
less than about 20 wt %) of substituted arenes. The amount and
structure of the substituted arenes depend on the process used in
the preparation of the divinylarene precursor to the divinylarene
dioxide. For example, divinylbenzene prepared by the
dehydrogenation of diethylbenzene (DEB) may contain quantities of
ethylvinylbenzene (EVB) and DEB. Upon reaction with hydrogen
peroxide, EVB produces ethylvinylbenzene monoxide while DEB remains
unchanged. The presence of these compounds can increase the epoxide
equivalent weight (as measured by ASTM D-1652) of the divinylarene
dioxide to a value greater than that of the pure compound but can
be utilized at levels of 0 to 99% of the epoxy resin portion.
[0028] In one embodiment, the divinylarene dioxide useful in the
present invention comprises, for example, DVBDO, a low viscosity
liquid epoxy resin. The viscosity of the divinylarene dioxide used
in the process of the present invention ranges generally from about
0.001 Pa s to about 0.1 Pa s, preferably from about 0.01 Pa s to
about 0.05 Pa s, and more preferably from about 0.01 Pa s to about
0.025 Pa s, at 25.degree. C.
[0029] The thermal stability of the divinylarene dioxides of the
present invention is sufficient to allow formulating or processing
the divinylarene dioxides at moderate temperatures (for example, at
temperatures of from about 100.degree. C. to about 200.degree. C.)
for up to several hours (for example, for at least 2 hours) without
oligomerization or homopolymerization. Oligomerization or
homopolymerization during formulation or processing is evident by a
substantial increase (e.g., greater than 50 fold) in viscosity or
gelling (crosslinking). The divinylarene dioxides of the present
invention have sufficient thermal stability such that the
divinylarene dioxides do not experience a substantial increase in
viscosity or gelling during formulation or processing at the
aforementioned moderate temperatures.
[0030] Another advantageous property of the divinylarene dioxide
useful in the present invention is its rigidity. The rigidity
property of the divinylarene dioxide is measured by a calculated
number of rotational degrees of freedom of the dioxide excluding
side chains using the method of Bicerano described in Prediction of
Polymer Properties, Dekker, New York, 1993. The rigidity of the
divinylarene dioxide used in the present invention may range
generally from about 6 to about 10, preferably from about 6 to
about 9, and more preferably from about 6 to about 8 rotational
degrees of freedom.
[0031] The concentration of the divinylbenzene dioxide in the
powder coating formulation of the present invention will depend on
what other formulation ingredients are used in the formulation and
will depend on the concentrations of the other formulation
ingredients. In general, the concentration of the divinylarene
oxide used in the present invention as component (a) of the
formulation may range generally from about 0.5 weight percent (wt
%) to about 99 wt % in one embodiment; from about 1 wt % to about
98 wt % in another embodiment; from about 2 wt % to about 95 wt %
in still another embodiment; and from about 5 wt % to about 90 wt %
in yet another embodiment, based on the weight of the total
composition.
[0032] In another embodiment, the epoxy resin powder coating
composition of the present invention includes at least one
divinylarene dioxide resin, wherein the divinylarene dioxide resin
comprises a blend of (a) at least one divinylarene dioxide
compound; and (b) at least one solid epoxy resin. The divinylarene
dioxide compound, component (a) of this embodiment, is the same as
the divinylarene dioxide compound described above. Generally, the
amount of divinylarene dioxide compound used in the present
invention to form the blend may be in the range of from about 0.1
wt % to about 50 wt %; and generally, the amount of the solid epoxy
resin for preparing the blend of the present invention may be in
the range of from about 99.9 wt % to about 50 wt %.
[0033] The solid epoxy resin, component (b) which makes up the
divinylarene dioxide resin blend of the powder coating composition
of the present invention, may include, for example, solid epoxy
resins known to those skilled in the art. A "solid epoxy resin" or
"SER" is defined herein as an epoxy-functional resin that has a Tg
generally greater than about 30.degree. C. Generally, the SERs
useful in the present invention are higher molecular weight (MW)
advanced epoxy resins made, for example, by advancing a lower
molecular weight liquid epoxy resin (LER) with a di-functional
compound such as a diphenol, a monomeric isocyanate and/or a
polymeric isocyanate.
[0034] For example, the LER resins useful in the present invention
include a wide variety of epoxy compounds. Typically, the epoxy
compounds are epoxy resins which are also referred to as
polyepoxides. Polyepoxides useful herein can be monomeric (for
example, the diglycidyl ether of bisphenol A, novolac-based epoxy
resins, and tris-epoxy resins), higher molecular weight advanced
resins (for example, the diglycidyl ether of bisphenol A advanced
with bisphenol A) or polymerized unsaturated monoepoxides (for
example, glycidyl acrylates, glycidyl methacrylate, allyl glycidyl
ether, etc.), homopolymers or copolymers. Most desirably, epoxy
compounds contain, on average, at least one pendant or terminal
1,2-epoxy group (that is, vicinal epoxy group) per molecule.
[0035] Examples of useful polyepoxides include the polyglycidyl
ethers of both polyhydric alcohols and polyhydric phenols;
polyglycidyl amines; polyglycidyl amides; polyglycidyl imides;
polyglycidyl hydantoins; polyglycidyl thioethers; epoxidized fatty
acids or drying oils, epoxidized polyolefins, epoxidized
di-unsaturated acid esters; epoxidized unsaturated polyesters; and
mixtures thereof. Polyepoxides can also be manufactured by reacting
diglycidyl ethers with isocyanates so as to obtain an
epoxy-terminated oligomer containing an oxazolidone structure for
example, the reaction products of a diglycidyl ether of bisphenol-A
and MDI.
[0036] Numerous polyepoxides prepared from polyhydric phenols
include those which are disclosed, for example, in U.S. Pat. No.
4,431,782. Polyepoxides can be prepared from mono-, di- and
tri-hydric phenols, and can include the novolac resins.
Polyepoxides can include the epoxidized cyclo-olefins; as well as
the polymeric polyepoxides which are polymers and copolymers of
glycidyl acrylate, glycidyl methacrylate and allylglycidyl ether.
Suitable polyepoxides are disclosed in U.S. Pat. Nos. 3,804,735;
3,892,819; 3,948,698; 4,014,771 and 4,119,609; and Lee and Neville,
Handbook of Epoxy Resins, Chapter 2, McGraw Hill, N. Y. (1967).
[0037] For example, polyepoxides useful as the LERs are glycidyl
polyethers of polyhydric alcohols or polyhydric phenols having an
epoxide equivalent weight (EEW) of from 150 to 300; preferably an
EEW of from 170 to 200; while an SER has an EEW of generally
greater than about 300. These LERs are usually made by reacting at
least two moles of an epihalohydrin or glycerol dihalohydrin with
one mole of the polyhydric alcohol or polyhydric phenol, and a
sufficient amount of a caustic alkali to combine with the
halohydrin. The products are characterized by the presence of more
than one epoxide group, that is, a 1,2-epoxy equivalency greater
than one.
[0038] In addition to the SER used in this embodiment, other epoxy
resins can be used in the present invention as optional additives
such as the LERs described above or other polyepoxides such as a
cycloaliphatic diene-derived epoxide. These polyepoxides can be
cured either thermally, cationically or photoinitiation (example UV
initiated cure). There are several cycloaliphatic epoxides that are
made and marketed by The Dow Chemical Company such as
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexyl carboxylate;
1,2-epoxy-4-vinylcyclohexane;
bis(7-oxabicyclo[4.1.0]hept-3-ylmethyl hexanedioic acid ester;
3,4-epoxycyclohexanecarboxylate methyl ester; and mixtures
thereof.
[0039] Other epoxy resins that may be used as optional additives in
the present invention are described in U.S. Patent Application Ser.
No. 61/267947, entitled "Epoxy Resins Compositions", filed Dec. 9,
2009 by Maurice Marks; which is incorporated herein by
reference.
[0040] The solid epoxy resin blended with a divinylarene dioxide
compound of the present invention advantageously provides a
modified epoxy resin with melt viscosities and softening points
lower than an unmodified epoxy resin. In addition the Tg of the
cured material from the modified epoxy resin is higher than the Tg
of the cured material from the unmodified epoxy resin.
[0041] In this embodiment of the present invention, the powder
coating composition including the divinylarene dioxide compound and
solid epoxy resin blend, such as when a SER is blended with DVBDO,
the melt viscosity of the resulting blend is reduced significantly
as measured by ASTM D-445 thus, improving the flow of the resulting
powder coating formulation as measured by ASTM D4242-07.
[0042] In still another embodiment, the epoxy resin powder coating
composition of the present invention includes at least one
divinylarene dioxide resin, wherein the divinylarene dioxide resin
comprises an epoxy terminated oxazolidonc resin (ETOR) prepared by
reacting (i) at least one divinylarene dioxide compound, and (ii)
at least one monomeric and/or polymeric isocyanate. In this
embodiment, the resultant reaction product is an ETOR useful for
preparing a curable powder coating composition with a balance of
beneficial properties. For example, powder coatings based on the
ETORs of the present invention have either (1) a higher Tg and
similar flexibility as measured by CSA Z245.20-06; or (2) a similar
Tg and higher flexibility (as measured by CSA Z245.20-06) compared
to powder coatings prepared from known SERs, PERs, and PHEs.
[0043] The divinylarene dioxide compound, component (i) useful for
forming the ETOR of the above embodiment, is the same as component
(a) described above. In addition, the monomeric and polymeric
isocyanates, component (ii) useful for forming the ETOR in this
embodiment, which in turn, is useful for forming the powder coating
composition of the present invention, may include, for example an
aliphatic monomeric isocyanate or aliphatic polymeric isocyanate;
an aromatic monomeric isocyanate or aromatic polymeric isocyanate;
or mixtures thereof. Suitable examples of the monomeric and
polymeric isocyanates include monomeric or polymeric isocyanates
selected from toluene diisocyanate, methylenediphenyl diisocyanate,
xylylene diisocyanate, isophorone diisocyanate, hexamethylene
diisocyanate, and mixtures thereof. Other ETORs useful in the
present invention are described, for example, in U.S. Pat. No.
5,112,932; and in U.S. Pat. No. 8,871,892; both references which
are incorporated herein by reference.
[0044] The epoxy terminated oxazolidone resins used in the present
invention bear terminal epoxide groups which allow the reaction of
the epoxy terminated oxazolidone resins with curing agents and/or
catalysts to form thermosets powder coatings. Upon crosslinking,
the resulting thermosets have high Tg and/or same flexibility.
[0045] In yet another embodiment, the epoxy resin powder coating
composition includes at least one divinylarene dioxide resin,
wherein the divinylarene dioxide resin comprises a phenolic
hardener prepared by reacting (A) at least one divinylarene
dioxide, and (B) at least one diphenol. In this embodiment, the
resultant reaction product formed by reacting (A) at least one
divinylarene dioxide compound, and (B) at least one diphenol is a
hydroxyl-function polyether useful for preparing a curable powder
coating composition. The novel hydroxyl-function polyethers of the
present invention increases the Tg of the powder coating as
measured by CSA Z245.20-06 compared to powder coatings prepared
from known SERs, PERs, and PHEs.
[0046] The divinylarene dioxide compound, component (A) of the
above embodiment, is the same as component (a) described above. The
diphenol, component (B), useful for forming the hydroxyl-function
polyether in the above embodiment, which in turn, is useful in
preparing the powder coating formulation of the present invention,
may comprise any of the diphenols well-known in the art, such as
for example, bisphenol A, bisphenol F, tetrabromobisphenol A, and
mixtures thereof. In one preferred embodiment, the diphenol useful
in the composition of the present invention comprises bisphenol A.
Other diphenols which may be used in the present invent are
described in U.S. Patent Application Ser. No. 61/141465 entitled
"Hydroxyl-Functional Polyethers and a Preparation Process
Therefor", filed Dec. 30, 2008 by Maurice Marks; which is
incorporated herein by reference.
[0047] Other optional components that may be useful in the powder
coating formulation of the present invention are components
normally used in coating formulations known to those skilled in the
art. For example, the optional components may comprise compounds
that can he added to the composition to enhance application
properties (e.g., surface tension modifiers or flow aids),
reliability properties (e.g., adhesion promoters), the reaction
rate, the selectivity of the reaction, and/or the catalyst
lifetime.
[0048] Examples of optional additives that may be added to the
coating compositions of the present invention include other resins
such as epoxy resins that are different from the divinylarene
dioxide compound, diluents, stabilizers, fillers, plasticizers,
catalyst de-activators, and the like; and mixtures thereof. Such
optional additives may be added to the reaction mixture during the
reaction or prior to recovery of the reaction product.
[0049] The concentration of the optional additives used in the
present invention may range generally from 0 wt % to about 99 wt %,
preferably from about 0.001 wt % to about 95 wt %, more preferably
from about 0.01 wt % to about 10 wt %, and most preferably from
about 0.05 wt % to about 5 wt %.
[0050] In a broad embodiment of the present invention, the solid
curable powder coating formulation includes, as one component, a
curing component. For example, when the divinylarene dioxide resin
is epoxy functional, the curing component may be an epoxy curing
agent,r an epoxy curing catalyst, or mixtures thereof. In another
embodiment, when the divinylarene dioxide resin is phenolic
functional, the curing component may be an epoxy resin, a blend of
an epoxy resin and a curing catalyst, or a mixture thereof. The
curing component used in the present invention is adapted to form a
solid powder coating.
[0051] The curing component, useful in the present invention,
includes for example, a compound which reacts with the reactive
groups of the divinylarene dioxide resin. For example, in cases
where the divinylarene dioxide resin is epoxy functional, the
curing component is an epoxy curing agent (also referred to as a
hardener or cross-linking agent), and may be catalytic or
co-reactive. This class of compounds forming the curing component,
useful for preparing the curable powder coating composition of the
present invention, may be any compound having an active group being
reactive with an epoxy group of an epoxy resin. For example, the
curing agent useful in the present invention includes
nitrogen-containing compounds such as amines and their derivatives;
oxygen-containing compounds such as carboxylic acid terminated
polyesters, anhydrides, phenol-formaldehyde resins,
amino-formaldehyde resins, phenol, bisphenol A and cresol novolacs,
phenolic-terminated epoxy resins; and catalytic curing agents such
tertiary amines, Lewis acids, Lewis bases and combinations of two
or more of the above curing agents.
[0052] Suitable curing components may also include, but are not
limited to, dicyandiamide, its derivate and adducts such as o-tolyl
biguanide (OTB); amino group containing compounds, imidazoles and
adduct of imidazoles, phenolic resins such bisphenol-A based,
phenol novolac or cresol-novolac phenolic resins; carboxyl
functional resins such as polyester and acrylic resins, blocked
isocyanates, anhydrides and others.
[0053] Polyamines, dicyandiamide, diaminodiphenylsulfone and their
isomers, aminobenzoates, various acid anhydrides, phenol-novolac
resins and cresol-novolac resins, for example, may be used as the
curing component in the present invention, but the present
invention is not restricted to the use of these compounds.
[0054] In another embodiment, in cases where the divinylarene
dioxide resin is phenolic functional, the curing component may
include an epoxy resin such as described above or the epoxy resin
in combination with a curing catalyst. For example, the curing
catalyst useful for preparing the curable powder coating
composition of the present invention, may include for example
imidazole derivatives, tertiary amines, and organic metallic salts.
Preferably, the curing catalyst is used in an amount from 0 to
about 20 parts by weight based on the total weight of the curable
powder coating composition of the present invention.
[0055] Generally, the amount of curing component used in the
present invention may be in the range of from about 0.01 wt % to
about 20 wt %.
[0056] The curable epoxy powder coating resin composition of the
present invention may also contain additives such as fillers, dyes,
pigments, thixotropic agents, photo initiators, latent catalysts,
inhibitors, additives to modify specific processing or coating
properties such as flow modifiers, accelerators, desiccating
additives, surfactants, adhesion promoters, fluidity control
agents, stabilizers, additives that aid in processing;
flexibilizers, and fire retardants; and any other substances which
are required for the manufacturing, application or proper
performance of the powder coating. The amount of the optional
additives used in the curable powder coating composition of the
present invention generally may be from 0 weight percent to about
70 weight percent depending on the final formulation.
[0057] In one preferred embodiment, the composition of composition
of the present invention may include a filler. The fillers that may
be used in the present invention can include for example,
wollastonite, barites, mica, feldspar, talc, calcium carbonate; and
pigments such as titanium dioxide, carbon black, iron oxides,
chrome oxide, organic pigments and dyes.
[0058] The process for preparing a curable powder coating
composition of the present invention includes mixing or blending
(I) the at least one divinylarene dioxide resin which has
previously been prepared as described above; (II) the at least one
curing component as described above; and (III) optionally, any of
the above-mentioned optional assorted formulation additives or
ingredients as desired that are not detrimental to the properties
of the curable powder coating composition when added. Any of the
optional additives, for example fillers, may be added to the
composition during the mixing or prior to the mixing to form the
composition.
[0059] In the preparation of the curable powder coating composition
of the present invention, the components described above are mixed
together by known means in the art at conditions to form a curable
composition. The curable powder coating composition of the present
invention can be produced by mixing all the components of the
composition together in any order. All the components of the
curable powder coating composition of the present invention are
typically mixed and dispersed at a temperature enabling the
preparation of an effective powder coating composition having the
desired properties. Compared to the compositions of the prior art,
cured products made from the powder coating compositions of the
present invention have a better balance of properties.
[0060] The flow of the resulting powder coating formulation
prepared by the process of the present invention as measured by
ASTM D4242-07 is generally lower than the corresponding formulation
prepared using analogous bisphenol A diglycidyl ether resin by at
least 5 percent (%), preferably by at least 10%, and most
preferably by at least 20%.
[0061] The Tg of the cured powder coating composition of the
present invention is generally greater than the corresponding
formulation prepared using analogous bisphenol A diglycidyl ether
resin by at least 3%, preferably by at least 4%, and most
preferably by at least 5% as measured by the glass transition
temperature (Tg) using differential scanning calorimetry (DSC).
[0062] The curable powder coating epoxy resin composition
containing the at least one divinylarene dioxide resin of the
present invention is used for preparing a coating on various
substrates. For example, the curable powder coating composition may
be applied to a substrate by any well known methods such as
electrostatic spraying, fluidized bed, electromagnetic brush,
powder cloud or by spraying the powder with conventional powder
spraying equipment onto the pre-heated substrate with or without
electromagnetic charging the powder (this method is also known as
fusion bonded process).
[0063] The curable powder coating composition of the present
invention can be cured according to typical processes practiced by
the industry. For example, curing the thermosettable or curable
powder coating composition of the present invention may be carried
out at a predetermined temperature and for a predetermined period
of time sufficient to cure the composition and the curing may be
dependent on the hardeners used in the formulation as known by
those skilled in the art of powder coatings. Typically, the curing
is carried out at a temperature, generally in the range of from
about 10.degree. C. to about 300.degree. C., preferably from about
50.degree. C. to about 275.degree. C., more preferably from about
75.degree. C. to about 250.degree. C., and most preferably from
about 100.degree. C. to about 240.degree. C. In another embodiment,
the temperature of curing can range generally from about ambient
temperature cure (for example, about 20.degree. C.) to elevated
temperature cures (for example, from about 100.degree. C. to about
250.degree. C.) using thermal, radiation or a combination of energy
sources.
[0064] As is generally known, the time of cure may range generally
from seconds to several hours depending on the curing agent and the
components in the curable resin compositions. Typically, the time
of curing may be, for example, from 1 minute to 30 minutes.
[0065] The curable composition can be cured in one step or multiple
steps or the curable composition can be post-cured using a
different temperature or energy source after the initial cure
cycle.
[0066] The Tg of the cured coatings is measured using a TA
Instruments DSC Q100. A 10.degree. C./minute temperature ramp from
30.degree. C. to 150.degree. C. may be carried out and the Tg is
measured considering the half-height of the heat flow curve. Upon
crosslinking, the thermoset coating product of the present
invention has a high Tg and/or good flexibility as measured by CSA
Z245.20-06.
EXAMPLES
[0067] The following examples and comparative examples further
illustrate the present invention in detail but are not to be
construed to limit the scope thereof.
[0068] In the following Examples, various terms and designations
are used such as for example:
[0069] "SER" stands for solid epoxy resin.
[0070] "DVBDO" stands for divinylbenzene dioxide.
[0071] "FBE" stands for Fusion Bonded Epoxy.
[0072] "EEW" stands for epoxide equivalent weight.
[0073] "BA" stands for hisphenol A.
[0074] "BADGE" stands for bisphenol A diglycidyl ether.
[0075] "MDI" stands for methylenediphenyl diisocyanate.
[0076] DER 664UE is a solid epoxy resin commercially available from
The Dow Chemical Company having an epoxide equivalent weight of 915
g/eq., a viscosity at 150.degree. C. of 6030 mPa-s, and a Tg of
60.degree. C.
[0077] DER 669E is a solid epoxy resin commercially available from
The Dow Chemical Company having an epoxide equivalent weight of
3200 g/eq.
[0078] DEH 87 is a phenolic curing agent commercially available
from The Dow Chemical Company having a phenolic equivalent weight
of 460 g/eq., a viscosity at 150.degree. C. of 1330 mPa-s, and a Tg
of 50.degree. C.
[0079] Epicure P 101 is an imidazole Liquid epoxy resin adduct
curing agent commercially available from Hexion.
[0080] Modaflow Powder III is a flow modifier and commercially
available from Solutia Inc.
[0081] Minspar 7 is a ground feldspar produced by IMERYS.
[0082] Cab-O-Sil M5 is an untreated fumed silica produced by
CABOT.
[0083] Amicure CC 1200 is a dicyandiamide (dicy), commercially
available from Air Products & Chemicals, Inc.
[0084] In the following Examples, standard analytical equipment and
methods are used such as for example:
[0085] Melt viscosity (.eta.) is measured by a parallel plate
rheometer at a temperature of 150.degree. C. and a frequency of 10
s.sup.-1.
[0086] Number average molecular weight (M.sub.n) is calculated
using the method of Miller and Macosko.
[0087] Mixture Tg and M.sub.n are calculated using the inverse
weight rule of mixtures, such that for mixture property P,
component weight fraction w.sub.i and component property P.sub.i:
1/P=w.sub.1/P.sub.1+w.sub.2/P.sub.2
[0088] Mixture melt viscosity is calculated using the logarithmic
rule of mixtures as follows:
ln(.eta.)=w.sub.1 ln(.eta..sub.1)+w.sub.2 ln(.eta..sub.2)
[0089] General Process for Producing a Thermoset from a Powder
Coating Composition
[0090] One embodiment of a general process for producing the
thermoset product form the powder coating of the present invention
may be as follows: a formulation of the present invention is
weighed in a semi-analytical scale and pre-blended in a high
intensity mixer PRIZM PILOT 3 for 30 seconds at 2300 rpm. The
pre-blended material is then extruded through a PRIZM 24 mm
extruder using 35.degree. C. in the feed zone of the extruder,
70.degree. C. in the middle zone of the extruder and 90.degree. C.
in the head of the extruder at 400 rpm. The extruded material is
fed to a chilled roll and then passed through a crusher, reducing
the chilled material to flakes. The crushed flakes are then fed to
a Hosokawa Micropul ACM-2 mill and reduced to a powder of
approximately 43 micron average particle size.
[0091] General Process for Applying a Powder Coating to a
Substrate
[0092] One embodiment of a general process for applying the powder
coating composition of the present invention on a substrate may be
as follows: a 1 inch.times.6 inches.times.5/8 inch
(2.5.times.15.0.times.1.6 centimeters) cold rolled steel bars are
prepared by shot blasting with steel grit to a white metal finish
with and anchoring profile between 2.5 and 4.5 mils. The steel bars
are then pre-heated to 242.degree. C. for 30 minutes in a
convection oven. The bars are then taken out of the oven and
immediately dipped in a fluidized bed containing the powder
coating. The dipping time is controlled to provide a coating on the
bars wherein the thickness of the coating is between 14 mils and 16
mils The coated bars are then taken back to the oven at 242.degree.
C. After 2 minutes in the oven, the bars are removed, allowed to
cool outside of the oven at ambient temperature for 2 minutes and
then immersed into a running water bath also at ambient temperature
until cold.
Comparative Example A
[0093] In this Comparative example A, a Fusion Bonded Epoxy (FBE)
powder coating formulation is prepared using a SER and a phenolic
resin. The FBE powder coating formulation is prepared by
compounding 512 g of DER 664UE with 262 g of DEH 87 phenolic curing
agent; 10 g of Epicure P 101; 10 g of Modaflow Powder III; 206 g of
Minspar 7; and 5 g of Cab-O-Sil M5. A steel bar as specified by CSA
Z245.20-06 is heated to 242.degree. C., and then the steel bar is
immersed in the above resulting powder coating formulation to give
a FBE coating on the steel bar. The FBE coating shows a Tg of
88.degree. C.
Comparative Example B
[0094] In this Comparative Example B, a FBE powder coating
formulation is prepared using an oxazolidone SER and a
dicyandiamide. The FBE powder coating formulation is prepared by
compounding 745 g of an oxazolidone solid epoxy resin prepared from
2 moles of BADGE and 1 mole of MDI with 39 g of dicyandiamide
(Amicure CG 1200); 10 g of Epicure P 101; 10 g of Modaflow Powder
III; 196 g of Minspar 7; and 5 g of Cab-O-Sil M5. A steel bar is
heated to 242.degree. C., and then the steel bar is immersed in the
above resulting powder coating formulation to give a FBE coating on
the steel bar. The FBE coating shows a Tg of 173.degree. C.
Comparative Example C
[0095] In this Comparative Example C, a FBE powder coating
formulation is prepared using a SER and a dicyandiamide. The FBE
powder coating formulation is prepared by compounding 766 g of DER
664UE with 18 g of dicyandiamide (Amicure CG 1200); 10 g of Epicure
P 101; 10 g of Modaflow Powder III; 196 g of Minspar 7; and 5 g of
Cab-O-Sil M5. A steel bar CSA Z245.20-06 is heated to 242.degree.
C., and then the steel bar is immersed in the above resulting
powder coating formulation to give a FBE coating on the steel bar.
The FBE coating shows a Tg of 103.degree. C.
Example 1
[0096] In this Example 1, a FBE powder coating formulation is
prepared using a SER and a bisphenol A-DVBDO phenolic resin. The
FBE powder coating formulation is prepared by compounding 602 g of
DER 664UE with 175 g of a BA-DVBDO phenolic hardener having a
viscosity at 150.degree. C. of 460 mPa-s and a Tg of 52.degree. C.;
10 g of Epicure P 101; 10 g of Modaflow Powder III; 203 g of
Minspar 7; and 5 g of Cab-O-Sil M5. A steel bar is heated to
242.degree. C., and then the steel bar is immersed in the above
resulting powder coating formulation to give a FBE coating on the
steel bar. The FBE coating shows a Tg of 93.degree. C.
Example 2
[0097] In this Example 2, a FBE powder coating formulation is
prepared using a DVBDO-oxazolidone SER and a dicyandiamide. The FBE
powder coating formulation is prepared by compounding 733 g of an
oxazolidone epoxy resin made from 2 moles of DVBDO and 1 mole of
MDI with 51 g of Amicure CG 1200; 10 g of Epicure P 101; 10 g of
Modaflow Powder III; 195 g of Minspar 7; and 5 g of Cab-O-Sil M 5.
A steel bar is heated to 242.degree. C., and then the steel bar is
immersed in the above resulting powder coating formulation to give
a FBE coating on the steel bar. The FBE coating shows a Tg of
196.degree. C.
Example 3
[0098] In this Example 3, a SER is blended with DVBDO. To a mixing
vessel is added 240 g of D.E.R. 669E epoxy resin and 24 g of DVBDO.
The resulting mixture is heated with stirring to ensure a
homogenous blend. The resulting SER blend has an epoxide equivalent
weight (EEW) of 715 g/eq, a M.sub.n of 1,430 g/mole, and a Tg of
63.degree. C.
Example 4
[0099] In this Example 4, a FBE powder coating formulation is
prepared using a SER-DVBDO blend and a dicyandiamide. The FBE
powder coating formulation is prepared by compounding 761 g of the
SER prepared in Example 3 with 22 g of Amicure CG 1200; 10 g of
Epicure P 101; 10 g of Modaflow Powder III; 196 g of Minspar 7; and
5 g of Cab-O-Sil M5. A steel bar is heated to 180.degree. C.; and
then the steel bar is immersed in the above resulting powder
coating formulation to give a FBE coating on the steel bar. The FBE
coating shows a Tg of 110.degree. C.
TABLE-US-00001 TABLE I Results Formulation % .DELTA. % .DELTA.
Viscosity Viscosity Cured Tg Epoxy (mPa-s, at (Control vs. Tg
(Control vs. Example Resin Hardener 150.degree. C.) Example)
(.degree. C.) Example) Comparative DER 664UE DEII 87 3170 88
Example A Example 1 DER 664UE BA - DVBDO 2560 -19 93 +6 phenolic
Comparative BADGE- dicy 173 Example B MDI Example 2 DVBDO- dicy 196
+13 MDI Comparative DER 664UE dicy 103 Example C Example 4 DER 669E
+ dicy 110 +7 DVBDO
* * * * *