U.S. patent application number 14/795088 was filed with the patent office on 2015-10-29 for siloxane-urethane foul release coatings.
The applicant listed for this patent is Dow Global Technologies LLC. Invention is credited to Hongyu Chen, Yanxiang Li, Paul J. Popa.
Application Number | 20150307745 14/795088 |
Document ID | / |
Family ID | 49816851 |
Filed Date | 2015-10-29 |
United States Patent
Application |
20150307745 |
Kind Code |
A1 |
Popa; Paul J. ; et
al. |
October 29, 2015 |
SILOXANE-URETHANE FOUL RELEASE COATINGS
Abstract
A two-part moisture curable coating compositions capable of
forming polyurethane-polysiloxane networks is provided. The coating
compositions which are useful in marine antifouling coatings
provide a two-part moisture curable composition comprising: (a) a
first part comprising at least one multifunctional polyol; (b) a
second part comprising: (i) at least one polysiloxane polymer with
at least two isocyanate or mercapto functional groups and (ii) at
least one isocyanate functional organic compound; and (c) solvent.
Also provided are methods of coating substrates with the curable
composition and articles produced from such coated substrates.
Inventors: |
Popa; Paul J.; (Auburn,
MI) ; Li; Yanxiang; (Midland, MI) ; Chen;
Hongyu; (Shanghai, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dow Global Technologies LLC |
Midland |
MI |
US |
|
|
Family ID: |
49816851 |
Appl. No.: |
14/795088 |
Filed: |
July 9, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14132119 |
Dec 18, 2013 |
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14795088 |
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Current U.S.
Class: |
427/387 ;
524/588 |
Current CPC
Class: |
Y10T 428/31551 20150401;
Y10T 428/269 20150115; C08G 18/61 20130101; C09D 7/63 20180101;
C08G 18/10 20130101; C09D 175/04 20130101; B05D 3/007 20130101;
C08G 18/77 20130101; C09D 183/08 20130101 |
International
Class: |
C09D 183/08 20060101
C09D183/08; B05D 3/00 20060101 B05D003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 31, 2012 |
CN |
201210599271.4 |
Claims
1. A two-part moisture curable composition comprising: (a) a first
part comprising: (i) at least one multifunctional polyol and (ii)
at least one polysiloxane polymer with at least two mercapto
functional groups; (b) a second part comprising at least one
isocyanate functional organic compound; and (c) solvent.
2. The composition of claim 1 wherein the polysiloxane polymer has
a number average molecular weight in the range of from 4,000 to
15,000.
3. The composition of claim 1 wherein the polysiloxane polymer is
from 2 to 40 weight percent based on the total solids weight of the
curable composition.
4. The composition of claim 1 wherein the multifunctional polyol is
selected from the group consisting of acrylic polyols, natural oil
polyols, polyester polyols, polyether polyols, polycarbonate
polyols, and blends thereof.
5. The composition of claim 1 wherein the multifunctional polyol is
an acrylic polymer with a Tg in the range of from 0.degree. C. to
45.degree. C. and a number average molecular weight in the range of
from 2,000 g/mol to 25,000 g/mol.
6. The composition of claim 1 wherein the multifunctional polyol is
from 35 to 60 weight percent based on the total weight of the
curable composition.
7. The composition of claim 1 wherein the isocyanate functional
organic compound is selected from the group consisting of
hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI),
methylene bis(p-cyclohexyl isocyanate) (H.sub.12MDI),
meta-tetramethylxylene diisocyanate (m-TMXDI), cyclohexyl
diisocyanate (CHDI), 1,3-bis(isocyanatomethyl)cyclohexane,
1,4-bis(isocyanatomethyl)cyclohexane, trimers of diisocyanates, and
blends thereof.
8. The composition of claim 1 wherein the isocyanate functional
organic compound is from 8 to 30 weight percent based on the total
weight of the curable composition.
9. The composition of claim 1 further comprising one or more of
pigments, dyes, gloss reducing additives, cure catalysts, flow and
leveling agents, degassing additives, adhesion promoters,
dispersion aids, flame-retardant agents, heat stabilizers, light
stabilizers, antioxidants, plasticizers, antistatic agents,
ultraviolet (UV) absorbers, lubricants or combinations thereof.
10. The composition of claim 9 wherein the adhesion promoter is
3-glycidoxypropyl trimethoxysilane.
11. The composition of claim 1 wherein: (a) the polysiloxane
polymer is from 2 to 40 weight percent based on the total solids
weight of the curable composition and has a number average
molecular weight in the range of from 4,000 to 15,000; (b) the
multifunctional polyol is from 35 to 60 weight percent based on the
total weight of the curable composition and is an acrylic polymer
with a Tg in the range of from 0.degree. C. to 45.degree. C. and a
number average molecular weight in the range of from 2,000 g/mol to
25,000 g/mol; and (c) the isocyanate functional organic compound is
from 8 to 30 weight percent based on the total weight of the
curable composition and is selected from the group consisting of
hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI),
methylene bis(p-cyclohexyl isocyanate) (H.sub.12MDI),
meta-tetramethylxylene diisocyanate (m-TMXDI), cyclohexyl
diisocyanate (CHDI), 1,3-bis(isocyanatomethyl)cyclohexane,
1,4-bis(isocyanatomethyl)cyclohexane, trimers of diisocyanates, and
blends thereof.
12. A method of coating a substrate comprising: (a) forming a
two-part moisture curable composition comprising: (i) a first part
comprising: (A) at least one multifunctional polyol and (B) at
least one polysiloxane polymer with at least two mercapto
functional groups; (ii) a second part comprising at least one
isocyanate functional organic compound; and (iii) solvent; (b)
optionally blending in one or more of pigments, dyes, gloss
reducing additives, cure catalysts, flow and leveling agents,
degassing additives, adhesion promoters, dispersion aids,
flame-retardant agents, heat stabilizers, light stabilizers,
antioxidants, plasticizers, antistatic agents, ultraviolet (UV)
absorbers, lubricants or combinations thereof; (c) applying the
composition of steps (a) and (b) to a substrate and curing the
composition.
13. A coated article made by the method of claim 12.
Description
[0001] This invention relates to two-part moisture curable coating
compositions capable of forming polyurethane-polysiloxane networks.
The coating compositions are useful in the field of marine
antifouling coatings.
[0002] Bio-fouling occurs everywhere in the marine environment and
is a significant problem for marine objects, such as ships. One
approach to limit fouling microorganisms from accumulating is to
use self-cleaning foul releasing coatings based on silicone
elastomers. Polydimethylsiloxane (PDMS) based silicone elastomer
foul release coatings have a rubbery elasticity, a low surface
energy and a smooth surface; making it easier for marine organisms
to detach from the coating surface under shear stress generated by
hydrodynamic drag. However, PDMS is soft, easily wears off, and
requires frequent reapplications; thereby costing time and money to
maintain.
[0003] One effective approach to improve the mechanical properties
of PDMS based silicone coating is to blend PDMS with other polymers
with better mechanical properties, such as polyurethane (PU).
Polysiloxanes and polyurethanes possess very different, but highly
useful, physical and mechanical properties which have led to their
widespread use. Polyurethanes stand out by virtue of mechanical
strength, elasticity, adhesion resistance and abrasion resistance
when combined with polydimethylsiloxane in foul releasing coatings.
However uniform physical blends of polysiloxanes and polyurethanes
are difficult to obtain, due to incompatible properties of these
resins and their pronounced tendency to undergo phase separation
following initial admixture.
[0004] U.S. Pat. No. 8,299,200 (claiming priority to the
international patent published as WO2009/025924) discloses a
polysiloxane-modified polyurethane coating prepared by reacting a
mixture comprising polyisocyanate; polyol; and polysiloxane having
functional groups capable of reacting with the polyisocyanate. The
functional groups capable of reacting with the polyisocyanate are
attached to only a single end of the polyorganosiloxane chain. It
is theorized that coatings that have a polysiloxane tethered at
only one end, can result is a highly mobile surface and may permit
easier release of fouling organisms. However, such siloxanes are
expensive and coatings prepared with this system fail to exhibit
all the required performance parameters of coatings in a marine
environment. U.S. Pat. No. 5,820,491 discloses a two-part urethane
topcoat including a polyol component, an isocyanate component and a
hydroxyl functional, polyether-modified polysiloxane copolymer
component. Coatings prepared with this system fail to exhibit all
the required performance parameters of coatings in a marine
environment. What is needed is an alternative, inexpensive, simple
and uniform coating composition that blends the properties of both
PDMS and PU and meets or exceeds the required performance
parameters of coatings in a marine environment.
[0005] The present invention provides a two-part moisture curable
composition comprising: (a) a first part comprising at least one
multifunctional polyol; (b) a second part comprising: (i) at least
one polysiloxane polymer with at least two isocyanate functional
groups and (ii) at least one isocyanate functional organic
compound; and (c) solvent. The present invention further provides a
method of coating a substrate comprising: (a) forming a two-part
moisture curable composition comprising: (i) a first part
comprising at least one multifunctional polyol; (ii) a second part
comprising: (A) at least one polysiloxane polymer with at least two
isocyanate functional groups and (B) at least one isocyanate
functional organic compound; and (iii) solvent; (b) optionally
blending in one or more of pigments, dyes, gloss reducing
additives, cure catalysts, flow and leveling agents, degassing
additives, adhesion promoters, dispersion aids, flame-retardant
agents, heat stabilizers, light stabilizers, antioxidants,
plasticizers, antistatic agents, ultraviolet (UV) absorbers,
lubricants or combinations thereof; and (c) applying the
composition of steps (a) and (b) to a substrate and curing the
composition.
[0006] The present invention further provides a two-part moisture
curable composition comprising: (a) a first part comprising: (i) at
least one multifunctional polyol and (ii) at least one polysiloxane
polymer with at least two mercapto functional groups; (b) a second
part comprising at least one isocyanate functional organic
compound; and (c) solvent. The present invention further provides a
method of coating a substrate comprising: (a) forming a two-part
moisture curable composition comprising: (i) a first part
comprising: (A) at least one multifunctional polyol and (B) at
least one polysiloxane polymer with at least two mercapto
functional groups; (ii) a second part comprising at least one
isocyanate functional organic compound; and (iii) solvent; (b)
optionally blending in one or more of pigments, dyes, gloss
reducing additives, cure catalysts, flow and leveling agents,
degassing additives, adhesion promoters, dispersion aids,
flame-retardant agents, heat stabilizers, light stabilizers,
antioxidants, plasticizers, antistatic agents, ultraviolet (UV)
absorbers, lubricants or combinations thereof; and (c) applying the
composition of steps (a) and (b) to a substrate and curing the
composition.
[0007] The term "polyol" is an alcohol molecule containing multiple
hydroxyl groups. The term "multifunctional polyol" means a polyol
that has more than one reactive site capable of cross-linking. The
term "polyurethane" means a resin in which the polymer units are
linked by urethane linkages, i.e., --O--CO--NH--, and/or one or
more urea linkages, i.e., --NH--CO--NH--. The term "isocyante"
means a functional group with the formula --N.dbd.C.dbd.O. The term
"mercapto" means a functional group with the formula --SH, which
may also be referred to as a thiol group.
[0008] The polysiloxane polymer of the present invention has the
formula:
##STR00001##
wherein each R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6,
R.sup.7, R.sup.8, R.sup.9, or R.sup.10 group is independently
selected from substituted or unsubstituted C.sub.1 to C.sub.60
hydrocarbon radicals, provided that (i) at least one of the R.sup.1
through R.sup.10 groups is substituted with an isocyanate
functional group or a mercapto group and (ii) the polysiloxane
polymer has at least two isocyante or mercapto functional groups.
Preferably, at least one of the R.sup.1 through R.sup.10 groups is
substituted with an isocyanate functional group and the
polysiloxane polymer has at least two isocyante functional groups.
Each of m and n is independently an integer from 0 and above,
provided that m+n.gtoreq.1. Preferably, the isocyanate functional
polysiloxane has a number average molecular weight in the range of
from 4,000 to 15,000, more preferably from 6,000 to 10,000. The
number average molecular weight is determined by GPC Viscotek
VE2001 using a Mixed D column and polystyrene standard. Examples of
suitable isocyanate functional polysiloxanes include without
limitation, Silmer.RTM. Di-50 and D-100 materials from Siltech
Corp., which are linear-difunctional polysiloxanes represented by
the formula:
##STR00002##
where a .gtoreq.1 and Silmer.RTM. C50 from Siltech Corp., a
multi-functional polysiloxane represented by the formula:
##STR00003##
where a.gtoreq.1 and b>1.
[0009] The polysiloxane polymer of the present invention makes up
from 2 to 40 weight percent based on the total solids weight of the
curable composition (i.e. excluding the solvent used in the curable
composition). Preferably the polysiloxane polymer is from 5 to 30
weight percent based on the total solids weight of the curable
composition and most preferably from 10 to 25 weight percent based
on the total solids weight of the curable composition.
[0010] The multi-functional polyol of the present invention may be
selected from acrylic polyols, natural oil polyols, polyester
polyols, polyether polyols, polycarbonate polyols, and blends
thereof. Acrylic polyols are preferred. Suitable acrylic polyols
include acrylic polymers that range in Tg from 0-45.degree. C.
preferably from 10-40.degree. C., and most preferably 20-35.degree.
C. and have number average molecular weights (Mn) in the range of
2,000-25,000 g/mol, preferably 3,000-15,000 g/mol and most
preferably 4,000-8,000 g/mol. Examples of commercially available
suitable acrylic polyols include Paraloid.TM. AU-750 from The Dow
Chemical Company, Paraloid.TM. AU-830 from The Dow Chemical
Company, Desmophen.RTM. A365 from Bayer Material Science AG, and
Joncryl.RTM. 500 from BASF Corporation. The multi-functional polyol
of the present invention makes up from 35 to 60 weight percent
based on the total weight of the curable composition. Preferably
the multi-functional polyol is from 40 to 55 weight percent based
on the total weight of the curable composition and most preferably
from 40 to 50 weight percent based on the total weight of the
curable composition. The glass transition temperature ("Tg" herein)
of the acrylic polymers are measured using a DSC from TA
Instruments Model Q100 V9.8 Build 296 with a standard Cell FC.
[0011] Suitable natural oil polyols (NOPs) include non-modified
NOPs, such as, for example, natural seed oil diol monomers; and
modified NOPs, such as, for example, commercially available Gen 1
NOP DWD 2080 from The Dow Chemical Company, which are reconstructed
NOP molecules with the monomers of saturated, mono-hydroxyl,
bi-hydroxyl and tri-hydroxyl methyl esters at a weight ratio of
approximately 32%, 38%, 28% and 2%. In another example, a
commercially available Gen 4 NOP is obtained by reacting Unoxol.TM.
diol and seed oil diol monomers which are separated from seed oil
monomer. Unoxol.TM. diol is a mixture of cis, trans-1,3- and cis,
trans-1,4-cyclohexane dimethanol, and is available from The Dow
Chemical Company. The Gen 4 NOP has following structure with the
hydroxyl equivalent weight of 170 g/mol.
##STR00004##
[0012] The natural oil derived polyols are polyols based on or
derived from renewable feedstock resources such as natural and/or
genetically modified plant vegetable seed oils and/or animal source
fats. Such oils and/or fats are generally comprised of
triglycerides, that is, fatty acids linked together with glycerol.
Preferred are vegetable oils that have at least about 70 percent
unsaturated fatty acids in the triglyceride. The natural product
may contain at least about 85 percent by weight unsaturated fatty
acids. Examples of preferred vegetable oils include, but are not
limited to, for example, those from castor, soybean, olive, peanut,
rapeseed, corn, sesame, cotton, canola, safflower, linseed, palm,
grapeseed, black caraway, pumpkin kernel, borage seed, wood germ,
apricot kernel, pistachio, almond, macadamia nut, avocado, sea
buckthorn, hemp, hazelnut, evening primrose, wild rose, thistle,
walnut, sunflower, jatropha seed oils, or a combination
thereof.
[0013] Additionally, oils obtained from organisms such as algae may
also be used. Examples of animal products include lard, beef
tallow, fish oils and mixtures thereof. A combination of vegetable
and animal based oils/fats may also be used.
[0014] The average hydroxyl functionality of the NOP is in the
range of from 1 to 10; preferably in the range of from 2 to 6. The
NOP may have a number average molecular weight in the range of from
100 to 3,000; preferably from 300 to 2,000; and more preferably
from 350 to 1,500.
[0015] Suitable isocyanate functional organic compounds include
aliphatic or cycloaliphatic polyisocyanates such as hexamethylene
diisocyanate (HDI), isophorone diisocyanate (IPDI), methylene
bis(p-cyclohexyl isocyanate) (H.sub.12MDI), meta-tetramethylxylene
diisocyanate (m-TMXDI), cyclohexyl diisocyanate (CHDI),
1,3-bis(isocyanatomethyl)cyclohexane and
1,4-bis(isocyanatomethyl)cyclohexane; trimers of diisocyanates such
as the trimer of hexamethylene diisocyanate (HDI) sold under the
trademark Desmodur.RTM.N-3390 from Bayer MaterialScience AG, the
trimer of isophorone diisocyanate (IPDI) sold under the tradename
Tolanate.RTM. IDT-70 from Perstorp Polyols, Inc., and blends
thereof. Preferably the isocyanate functional organic compounds are
trimers of hexmethylene diisocyanate (HDI) and isophorone
diisocyanate (IPDI); and most preferably trimers of hexamethylene
diisocyanate (HDI). The isocyanate functional organic compounds of
the present invention make up from 8 to 30 weight percent based on
the total weight of the curable composition. Preferably isocyanate
functional organic compounds are from 10 to 30 weight percent based
on the total weight of the curable composition and most preferably
from 15 to 25 weight percent based on the total weight of the
curable composition.
[0016] Suitable urethane grade solvents include aromatic
hydrocarbons such as xylene, toluene; ketones such as methyl
isobutyl ketone, methyl amyl ketone, or acetone, esters such as
butyl acetate, or hexyl acetate; glycol ether esters such as
propylene glycol monomethyl ether acetate; esters such as propyl
propionate or butyl propionate, and blends thereof. The solvent
makes up from 10 to 60 weight percent based on the total weight of
the curable composition. Preferably solvent is from 15 to 50 weight
percent based on the total weight of the curable composition and
most preferably from 20 to 40 weight percent based on the total
weight of the curable composition.
[0017] The curable compositions are useful as coatings and may
include various additives ordinarily incorporated in compositions
of this type. Examples of additional additives include, but are not
limited to, pigments, dyes, gloss reducing additives, cure
catalysts, flow and leveling agents, degassing additives, adhesion
promoters, dispersion aids, flame-retardant agents, heat
stabilizers, light stabilizers, antioxidants, plasticizers,
antistatic agents, ultraviolet (UV) absorbers, lubricants or
combinations including one or more of the foregoing additives.
[0018] Suitable adhesion promoters include silane adhesion
promoters, such as 3-glycidoxypropyl trimethoxysilane, which can
enhance the wet adhesion of the fouling release top coat without
the need for a mid or tie coat. Preferably the silane adhesion
promoter is in the range of from 0.5 to 3 weight percent based on
the total weight of the curable composition, more preferably from 1
to 3 weight percent based on the total weight of the curable
composition, and most preferably from 1.5 to 3 weight percent based
on the total weight of the curable composition.
[0019] Curable coating compositions of the present invention can be
un-pigmented transparent clear coats, or pigmented systems for
primer, basecoat and topcoat applications. The pigment may be any
typical organic or inorganic pigment. Several different pigments
may be needed to achieve a desirable color for a particular
application. Examples of suitable pigments include without
limitation, titanium dioxide, barytes, clay, calcium carbonate, red
iron oxide, CI Pigment Yellow 42, CI Pigment Blue 15, 15:1, 15:2,
15:3, 15:4 (copper phthalocyanines), CI Pigment Red 49:1, CI
Pigment Red 57:1 and carbon black.
[0020] The resulting coating compositions can be applied onto a
substrate using techniques known in the art; e.g. by spraying,
draw-down, roll-coating. The nominal dry film thickness (DFT) of
the coating is greater than or equal to 2 mils, preferably greater
than 2.5 mils and more preferably greater than 3 mils. Examples of
substrates that may be coated include without limitation, plastics,
wood, metals such as aluminum, steel or galvanized sheeting,
tin-plated steel, concrete, glass, composites, urethane elastomers,
primed (painted) substrates, and the like. The coatings can be
cured at room temperature or at an elevated temperature in a forced
air oven or with other types of heating sources.
[0021] The following examples are illustrative of the
invention.
Experimental Methods
[0022] The raw materials used in the Examples are described
below.
Raw Materials
TABLE-US-00001 [0023] Material Function Supplier Acrylic Polyol A
comprises by weight, in Polyol Synthesized in polymerized form, 42%
methyl methacrylate laboratory. (MMA), 30% hydroxyethylmethacrylate
(HEMA) and 28% butyl acrylate (BA), with a Tg of 31.degree. C., a
solution hydroxyl equivalent weight of 552 at 80.3% solids and a Mn
of 4600. Acrylic Polyol B comprises by weight, in Polyol
Synthesized in polymerized form, 30% MMA, 30% HEMA and laboratory.
40% BA, with a Tg of 14.degree. C., a solution hydroxyl equivalent
weight of 551 at 76.4% solids and a Mn of 3800. Acrylic Polyol C
comprises by weight, in Polyol Synthesized in polymerized form, 16%
MMA, 30% HEMA and laboratory. 54% BA, with a Tg of -3.degree. C., a
solution hydroxyl equivalent weight of 557 at 73.1% solids and a Mn
of 5000. Acrylic Polyol D is the same composition as Polyol
Synthesized in Acrylic Polyol A, but with a solution hydroxyl
laboratory. equivalent weight of 610 at 77.5% solids and a Mn of
3500. Polyester 1 (Natural Oil Polyol) with a solution Polyol The
Dow Chemical hydroxyl equivalent weight of 170 at 77.5% Company
solids Polyester 2 (CAPA .TM. 3091 polycaprolactone), Polyol
Perstorp Polyols, CAS Number 37625-56-2 with a molecular Inc.
weight of 900. Polyester 3 (CAPA .TM. 3050 polycaprolactone),
Polyol Perstorp Polyols, CAS Number 37625-56-2 with a molecular
Inc. weight of 540. Silmer .RTM. NCO Di-50, molecular weight of
4300 Isocyanate Siltech Corp. g/mol according to manufacturer
functional PDMS Silmer .RTM. NCO Di-100, molecular weight of 8000
Isocyanate Siltech Corp. g/mol according to manufacturer functional
PDMS Silmer .RTM. NCO C-50, molecular weight of 12,400 Isocyanate
Siltech Corp. g/mol according to the manufacturer functional PDMS
Desmodur .RTM. N3390 aliphatic polyisocyanate (HDI Isocyanate Bayer
Trimer 90% solids in butyl acetate) functional organic
MaterialScience AG compound Tolanate .RTM. IDT-70 aliphatic
polyisocyante (IPDI Isocyanate Perstorp Polyols, Trimer 70% Solids
in butyl acetate) functional organic Inc. compound Siloxane 1
(MCR-C62 mono-dicarbinol Hydroxy functional Gelest, Inc. terminated
polydimethylsiloxane), with a PDMS molecular weight of 5,000
Siloxane 2 (Dow Corning .RTM. 54 Additive dimethyl, Hydroxy
functional Dow Corning methyl(polypropylene oxide) siloxane), CAS
siloxane Corporation Number 68957-00-6, Siloxane 3 (Dow Corning
.RTM. 29 Additive Hydroxy functional Dow Corning
octamethylcyclotetrasiloxane and siloxane Corporation
decamethylcyclopentasiloxane), CAS Numbers 556-67-2 and 541-02-6
n-Butyl Propionate Solvent The Dow Chemical Company n-Propyl
Propionate Solvent The Dow Chemical Company Methyl Isobutyl Ketone
(MIBK) Solvent Honeywell Burdick- Jackson, a subsidiary of
Honeywell International, Inc. Z-6040 silane (glycidoxypropyl
trimethoxy- Silane adhesion Dow Corning silane) promoter
Corporation Dibutytin dilaurate (DBTDL) Catalyst Sigma-Aldrich
Co.
Test Procedures:
Pseudo-Barnacle Pull Off Strength Test
[0024] The test was carried out according to a modified procedure
as described in reference (Kohl JG& Singer IL, Pull-off
behavior of epoxy bonded to silicone duplex coatings, Progress in
Organic Coatings, 1999, 36:15-20) using an Instron machine under
the trade designation Instron.TM. Model 1122. Ten-millimeter
diameter aluminum studs were used and glued to the surface of the
coated panels using an epoxy adhesive (Hysol.RTM. 1C from Henkel
Loctite Americas, www.loctite.com). The excessive epoxy was trimmed
after about one hour cure. The epoxy adhesive was then allowed to
harden for at least three days at room temperature. The stud was
then pulled off using an Instron machine until the stud detached
from the coating surface. For each test, at least two and
preferably three replicate samples were employed and the average
value for pull off strength (measured in MPa units) was recorded.
The threshold of pseudo-barnacle pull off strength was 0.6 MPa.
Contact Angle Test
[0025] The water contact angle of the coatings was measured using a
VCA Optima contact angle measuring device from AST Products, Inc. A
water droplet, 0.5-1 .mu.l was placed on the coating surface. After
the equilibrium time the contact angle was measured. A higher
contact angle means the coating surface is hydrophobic. For a
fouling release coating the contact angle should be
.gtoreq.100.degree..
Impact Resistance
[0026] The impact resistance of the coating was determined by using
a Gardner impact tester according to ASTM D2794. This test involves
dropping a weight onto an indenter which is resting on the surface
of the coating. The weight is dropped from a known height and the
indenter forms a dimple in the coated panel. The coating is
observed for cracking or delaminating on or around the dimple. The
force to produce cracking/delaminating is recorded in inch-pounds
(in-lb). The highest force that does not result in coating failure
up to 160 in-lbs is recorded. The test is performed by impacting
the coating directly (direct), coating facing upward. The threshold
of impact resistance was 80 in-lbs.
Cross Hatch Adhesion
[0027] Cross hatch adhesion was measured according to ASTM D3359. A
rating of 4B or 5B is considered an acceptable level of
adhesion.
Adhesion--Hot Water Immersion
[0028] The cured panels were immersed in hot water (80.degree. C.)
for 5 days. Upon completion the panels were removed from the hot
water bath, dried and allowed to cool to ambient lab temperatures.
The coatings were visually inspected for delaminating, blistering,
bubbling, etc. in the scribed area from the cross-hatch adhesion
test. If no damage was observed, the top coat was rated as a pass
for adhesion.
Coating Application & Cure
[0029] Coatings were applied to 4 inch by 12 inch aluminum chromate
pre-treated and steel phosphate pre-treated panels using a wire
wound rod or a 8 path wet film applicator. The panels were
pre-cleaned by wiping with a lint free cloth and IPA to remove oils
and dried with compressed air or nitrogen. The coated panels were
allowed to cure for a minimum of 7 days at 50% relative humidity
(RH) and ambient laboratory temperatures (.about.24.degree. C.)
prior to testing.
Formulations:
EXAMPLES 1-29 & COMPARATIVE EXAMPLES 1-3
[0030] The coating formulations were prepared in a FlackTek
SpeedMixwer.TM. (Model DAC 150 FV-K, FlackTek, Inc.) dual
asymmetric centrifuge. The formulations were prepared as
follow:
1. A solvent blend was prepared from equal parts by weight of MIBK,
n-butyl propionate, and n-propyl propionate unless another solvent
was specified in the formulation tables 2. A 1% catalyst solution
was prepared using the above solvent blend and 1% DBTDL 3. The
polyols, solvents, and catalyst solution, and adhesion promoter (if
present in formulation) were charged to a SpeedMixer cup 4. The
blend was mixed for 30 seconds at .about.3000 rpm 5. The isocyanate
functional components were added to the SpeedMixer cup 6. The blend
was mixed for 30 seconds at .about.3000 rpm 7. Panels were coated
and allowed to cure as described above
TABLE-US-00002 Examples 1 2 3 4 5 6 Material Solids Eq Wt G G G G G
G Acrylic Polyol A 80.3 552 11 11 Acrylic Polyol B 76.4 551 12 12
Acrylic Polyol C 73.1 557 12 12 Desmodur N3390 90 214 4.4 4.8 4.8
4.4 4.8 4.8 Silmer NCO C-50 100 4133 1.5 1.5 1.5 Silmer NCO Di-100
100 3950 1.4 1.5 1.5 1% DBTDL 1 0.3 0.3 0.3 0.3 0.3 0.3 Solvent
Blend 0 4.7 4.3 3.7 4.6 4.4 3.6
Testing Results for Examples 1-6
TABLE-US-00003 [0031] Pseudo-Barnacle Impact Contact Adhesion
Direct Indirect Example Angle MPa In-lbs In-lbs 1 107.degree. 0.18
>160 >160 2 109.degree. 0.23 >160 >160 3 106.degree.
0.23 >160 >160 4 106.degree. 0.11 >160 >160 5
106.degree. 0.12 >160 >160 6 106.degree. 0.16 >160
>160
[0032] These results illustrate that acrylic polyols of different
glass transition temperatures yield coatings with excellent
toughness as illustrated by the impact resistance results and
release properties. They also illustrate that different level of
isocyanate functionality on the PDMS polymers (Silmer C-50 is a
tri-functional whereas Silmer Di-100 is di-functional) provide the
same results. The level of isocyanate functional PDMS in these
examples is 10% based on total solids in the formulation.
TABLE-US-00004 Examples 7 8 9 10 11 12 Material Solids Eq Wt G G G
G G G Acrylic Polyol A 80.3 552 13 12.5 11 13.1 12.4 11 Desmodur
N3390 90 214 5.2 4.9 4.2 5.3 5 4.3 Silmer NCO Di-50 100 2150 0.8
1.6 3.1 Silmer NCO Di-100 100 3950 0.8 1.6 3.2 1% DBTDL 1 0.4 0.4
0.3 0.4 0.4 0.3 Solvent Blend 0 4.2 5.2 6.9 4.2 5.2 7.1
Testing Results for Examples 7-12
TABLE-US-00005 [0033] Pseudo-Barnacle Impact Contact Adhesion
Direct Indirect Example Angle MPa In-lbs In-lbs 7 103.degree. 0.24
>160 >160 8 103.degree. 0.3 >160 >160 9 109.degree.
0.24 >160 >160 10 105.degree. 0.23 >160 >160 11
103.degree. 0.16 >160 >160 12 100.degree. 0.08 >160
>160
[0034] These results illustrate that different level of the
isocyanate functional PDMS provide tough coatings (impact
resistance) and good release properties. The range of isocyanate
functional PDMS in these formulations is between 5-20% based on
total solids in the formulation. They also highlight that different
MW isocyanate functional PDMS polymers can be used: Silmer NCO
Di-50 (MW 4300 g/mol) and Silmer NCO Di-100 (MW 8000 g/mol).
TABLE-US-00006 Examples 13 14 15 Material Solids Eq Wt G G G
Acrylic Polyol A 80.3 552 10.2 9.2 11 Desmodur N3390 90 214 3.9 3.5
4.4 Silmer NCO Di-100 100 3950 3.9 4.5 3.2 1% DBTDL 1 0.3 0.3 0.3
Solvent Blend 0 7.9 8.6 7.1
Testing Results for Examples 13-15
TABLE-US-00007 [0035] Pseudo-Barnacle Impact Contact Adhesion
Direct Indirect Example Angle MPa In-lbs In-lbs 13 102.degree. 0.1
>160 120 14 101.degree. 0.11 >160 80 15 100.degree. 0.13
>160 100
[0036] These results further expand the level of the isocyanate
functional PDMS to provide tough coatings (impact resistance) and
good release properties. The range of isocyanate functional PDMS in
these formulations is between 20-30% of the totals solids in the
formulation.
TABLE-US-00008 Examples 16 17 Material Solids Eq Wt G G Acrylic
Polyol D 80.27 552 10.2 11 Desmodur N3390 90 214 3.6 3.9 Silmer NCO
Di-100 100 3950 3.7 3 1% DBTDL 1 0.3 0.3 Solvent Blend 0 6.9
6.8
Testing Results for Examples 16 and 17
TABLE-US-00009 [0037] Pseudo-Barnacle Impact Contact Adhesion
Direct Indirect Example Angle MPa in/lbs in/lbs 16 103.degree. 0.24
>160 >160 17 101.degree. 0.26 >160 >160
[0038] This data confirms the earlier data at 20 and 25% isocyanate
functional PDMS in the formulations using a new lot of Acrylic
Polyol A, labeled Acrylic Polyol D (slightly higher OH equivalent
weight) still illustrating excellent toughness (impact resistance)
and release properties.
TABLE-US-00010 Example Example 18 19 Material Solids Eq Wt G G
Polyester 1 100 165 7.2 0 Polyester 2 100 306.6 0 8 Desmodur N3390
90 214 9.5 5.6 Silmer NCO Di-100 100 3950 5.4 4.4 1% DBTDL 1 0.3
0.3 Solvent Blend 0 13.1 10.9
Testing Results for Examples 18 and 19
TABLE-US-00011 [0039] Pseudo-Barnacle Impact Contact Adhesion
Direct Example Angle MPa in/lbs 18 105.degree. 0.2 >160 19
121.degree. 0.57 >160
[0040] This data confirms that polyols other than acrylic can be
used. However, acrylic polyols are preferred.
TABLE-US-00012 Examples 20 21 22 23 24 25 Material Solids Eq Wt G G
G G G G Acrylic Polyol D 77.5 609.7 4.5 4.5 4.5 4.5 11 10.2
Desmodur N3390 90 214 1.6 1.6 1.6 1.6 3.9 3.6 Silmer NCO Di-100 100
3950 1.7 1.7 1.7 1.7 3 3.7 1% DBTDL 1 0.1 0.1 0.1 0.1 0.3 0.3
Solvent Blend 0 3.1 3.1 3.1 3.1 6.8 6.9
Testing Results for Examples 20-25
TABLE-US-00013 [0041] Overcoat Pseudo-Barnacle Interval Adhesion
Cross Hatch Hot Water Example Hours MPa Adhesion Adhesion 20 24
0.32 5B Pass 21 48 0.29 5B Pass 22 72 0.23 5B Pass 23 96 0.31 5B
Pass 24 168 0.2 5B Fail 25 168 0.23 5B Fail
[0042] Examples 20-25 demonstrate that a tie or mid coat layer is
not required to achieve acceptable fouling release properties and
adhesion to the primer. Examples 20-25 were prepared as described
above and applied to treated metal panels that were primed with a
commercial marine epoxy primer (Interguard 264 manufacturer by
International Paint) per the manufacturer's recommendations. The
primer was applied to the panels and allowed to cure for 24, 48,
72, 96, and 168 hours respectively (Ex 20-25--examples 24 & 25
applied after 168 hours--different levels of silicone) and allowed
to cure as described above.
[0043] These examples demonstrate that excellent release properties
can be achieved without the use of a tie or mid coat applied
between a primer and the fouling release top coat. These results
also show a preferred over coat window between applying the top
coat over the primer between 24 and 144 hours, preferably between
24 and 120 hours, and more preferably between 48-96 hours with
excellent adhesion as demonstrated by the hot water adhesion
test.
TABLE-US-00014 Examples 26 27 28 29 Material Solids Eq Wt G G G G
Acrylic Polyol D 77.5 609.7 4.2 4.2 4.2 4.2 Desmodur N3390 90 214
1.4 1.5 1.5 1.5 Silmer NCO Di-100 100 3950 1.6 1.6 1.6 1.6 Z-6040
100 0.2 0.2 0.2 0.2 1% DBTDL 1 0.1 0.1 0.1 0.1 Solvent Blend 0 3.1
3.0 3.0 3.0
Testing Results for Examples 26-29
TABLE-US-00015 [0044] Overcoat Pseudo-Barnacle Interval Adhesion
Cross Hatch Hot Water Example Hours MPa Adhesion Adhesion 26 24
0.32 5B Pass 27 48 0.24 5B Pass 28 72 0.26 5B Pass 29 96 0.25 5B
Pass
[0045] Examples 26-29 demonstrate that a silane adhesion promoter
can be used to further enhance the wet adhesion of the fouling
release top coat without the need for a mid or tie coat.
[0046] Examples 24-27 were prepared as described above and applied
to treated metal panels that were primed with a commercial marine
epoxy primer (Interguard 264 manufacturer by International Paint)
per the manufacturer's recommendations. The primer was applied to
the panels and allowed to cure for 24, 48, 72 or 96 hours
respectively (Ex 24-27). The nominal dry film thickness (DFT) of
the primer was between 4-4.5 mils. The top coat was applied to
achieve a DFT of >2.5 mils and allowed to cure as described
above.
[0047] These examples demonstrate that excellent release properties
can be achieved without the use of a tie or mid coat applied
between a primer and the fouling release top coat with excellent
adhesion as demonstrated by the hot water adhesion test when a
silane adhesion promoter is added to the top coat formulation.
Visually the panels for examples 26-29 looked better after the hot
water adhesion test than those of examples 20-23. The range of
silane adhesion promoter should be between 0.5-3% based on weight,
preferably between 1-3% % based on weight, and more preferably
between 1.5-3% based on weight.
Comparative Examples
[0048] The comparative examples below are 2K urethane systems.
However they are differentiated from the present invention in
performance and in cured coating composition.
TABLE-US-00016 Comparative Examples 1 2 3 Material Solids Eq Wt G G
G Polyester 3 90 201 5.5 5.5 5.5 Tolanate IDT 70 70 343 10.50 10.6
10.8 Siloxane 1 100 2500 1.40 0 0 Siloxane 2 100 2000 0 1.4 0
Siloxane 3 100 1200 0 0 1.4 1% DBTDL 1 0.3 0.3 0.3 n-butyl acetate
0 3.4 3.4 3.5
Results for Comparative Examples 1-3
TABLE-US-00017 [0049] Pseudo-Barnacle Comparative Contact Adhesion
Cross Hatch Hot Water Example Angle MPa Adhesion Adhesion 1
91.degree. 0.06 5B Fail 2 74.degree. 0.13 5B Fail 3 50.degree. 0.02
5B Fail
[0050] None of the contact angles met the threshold for a fouling
release coating exhibiting a water contact angle of
.gtoreq.100.degree.. The coating quality for each of the
comparative examples was extremely poor due to severe blooming of
the siloxane component that could be easily wiped from the surface.
Although the pseudo-barnacle adhesion meets the requirement, none
of the coatings passed the hot water adhesion test after
immersion--all of the coating severely delaminated from the
substrate and cracked. These comparative examples highlight the
performance advantages of the present invention compared to other
2K urethane fouling release technologies, by exhibiting better
adhesion without a mid or tie coat and better coating quality.
* * * * *
References