ONE COMPONENT POLYUREA COATING

REVETEMENT DE POLYUREE EN CONSTITUANT UNIQUE

English Abstract

A new one-component polyurea coating composition which is curable at
ambient temperature and comprises, a quasi-prepolymer isocyanate, having an NCO
content of about 7 to about 30, a polyamine resin component in the form of a Schiff base
blocked amine dispersed throughout the isocyanate, and said composition being formulated
at an index between about 100 to 160, and wherein the composition is moisture insensitive,
and no catalyst is required to effectuate curing.

French Abstract

Nouvelle composition de revêtement de polyurée à un seul constituant, réticulable à température ambiante et comprenant un isocyanate de type quasi-prépolymère, avec une teneur en NCO d'environ 7-30, une résine de polyamine sous forme d'amine bloquée par une base de Schiff, dispersée dans l'ensemble de l'isocyanate; ladite composition est formulée à un indice se situant dans une plage de 100-160; la composition n'est pas sensible à l'humidité, et sa réticulation ne requiert aucun catalyseur.

Claims

What Is Claimed Is:
1. A new one-component polyurea coating composition which is curable
at ambient temperature and comprises,
(A) a quasi-prepolymer isocyanate, having an NCO content of about 7 to
about 30,
(B) a polyamine resin component in the form of a Schiff base blocked
amine dispersed throughout the isocyanate,
said composition being formulated at an index between about 100 to
160, and wherein the composition is moisture insensitive.
2. The composition of claim 1 wherein,
no catalyst is required to effectuate curing.
3. The composition of claim 2 wherein,
said NCO content is about 9 to about 18,
said index is between about 100 to about 140.
4. The composition of claim 1 wherein,
said NCO content is about 10 to about 16,
said index is between about 105 to about 130.
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5. The composition of claim 1 wherein,
said NCO content is about 9 to about 18,
said index is between about 100 to about 140, and
said polyamine resin component contains one or more products having the formula:
<IMG>
wherein R' independently represents hydrogen or methyl, and x is a number having an
average value of about 1 to about 60.
6. The composition of claim 1 wherein,
said NCO content is about 9 to about 18,
said index is between about 100 to about 140, and
said polyamine resin component contains one or more products having the formula:
<IMG>
where, x+y+z = 3.0 to 70, and
wherein R' independently represents hydrogen or methyl, and x is a number having an
average value of about 1 to about 60.
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7. The composition of claim 1 wherein,
said NCO content is about 9 to about 18,
said index is between about 100 to about 140, and wherein the
composition is moisture insensitive, and a coating applied from the composition will cure
without detriment regardless of possible high moisture content.
8. The composition of claim 1 wherein,
said NCO content is about 9 to about 18,
said index is between about 100 to about 140, and the polyamine resin
component is a polyoxyalkylene amine useable in conjunction with either an aromatic or
cycloaliphatic diamine cross-linker.
9. The composition of claim 1 wherein,
said NCO content is about 9 to about 18,
said index is between about 100 to about 140, and wherein said
polyamine resin component is a combination of high and low molecular weight difunctional
and trifunctional polyoxyalkylene amines.
10. The composition of claim 3 wherein,
said composition has a pot life of at least 3 hours to about 24 hours.
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11. The composition of claim 1 wherein,
said NCO content is about 9 to about 18,
said index is between about 100 to about 140, and a combination of
diamines and triamines is used for the polyamine resin component.
12. The composition of claim 1 wherein,
said NCO content is about 9 to about 18,
said index is between about 100 to about 140, and the volumetric ratio
of the A component to the B component is within the range of about 75:25 to about 25:75.
13. The composition of claim 1 wherein,
said NCO content is about 9 to about 18,
said index is between about 100 to about 140, and the volumetric ratio
of the A component to the B component is within the range of about 60:40 to about 40:60.
14. The composition of claim 1 wherein,
said NCO content is about 9 to about 18,
said index is between about 100 to about 140, and the volumetric ratio
of the A component to the B component is about 50:50.
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15. The composition of claim 13 wherein,
said composition after application is tack free within 20 to 60 minutes.
16. The composition of claim 1 wherein,
said NCO content is about 9 to about 18,
said index is between about 100 to about 140, and the composition
is suitable for one component single container shipment.
17. The composition of claim 1 wherein,
said NCO content is about 9 to about 18,
said index is between about 100 to about 140, and wherein a coating
applied from the composition is tack-free within about one to three minutes.
18. The composition of claim 14 wherein,
said composition after application is tack free within 20 to 60 minutes.
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Description

CA 02242132 1998-06-30
ONE COMPONENT POLYUREA COATING
This application is a continuation in part of applicant's copending U.S.
provisional application, Serial No. 60/056,212, filed August 21, 1997.
B~ck~round Of The Invention
This invention broadly relates to a new one component polyurea coating
system. There are several pertinent differences between this invention and prior art
coatings that are important: (1) This invention is truly amine cured (urea linkages) and
is moisture initi~ted only. Existing systems typically have been full prepolymers comprised
of polyisocyanates and polyols which react to form urethane linkages. The excess NCO
content of the full prepolymers are typically in the range of 3.0 to 4Ø The final cure is
accomplished by reaction with atmospheric moisture which does form urea linkages as
follows: the moisture (water) reacts slowly with the isocyanate (3-4 NCO content) to forrn
carbamic acid, which then quickly dissociates to forrn an amine, which can then react with
isocyanate to form urea linkages. The percentage of urea linkage is low since the
prepolymer contains urethane linkages. Typical moisture cure elastomer systems require
a catalyst. In this invention no catalysts are required. However, a catalyst can be used if
desired. An important advantage of this invention is that these systems are extremely
moisture insensitive. They do not liberate CO2 with exposure to atmospheric moisture
caused by reaction of the isocyanate and water. Atmospheric moisture reacts with the
complexed Schiff bases, decomposing them into their constituent amines, which, in turn
react rapidly with the isocyanate. Atmospheric moisture-isocyanate-carbamic acid reaction
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CA 02242132 1998-06-30
proceeds very slowly and is essentially eliminated by the much more aggressive moisture-
Schiff base reaction. As a result, the coatings of this invention will cure without
detriment, regardless of high moisture content. Existing moisture cured urethanes do
liberate CO2 gas as a by-product. That gas must have time to migrate to the coating
surface and escape in order to have as a solid polymer and not have reduced density due
to entrapped cellular. (2) This invention works well with quasi-prepolymers having NCO
contents of 8 and higher, i.e., all of the way to "one-shot" non-prepolymerized isocyanates
having NCO content of around 30. Existing earlier systems typically were based upon full
prepolymers (polyurethane linkages) having NCO contents of around 3.0 to 4Ø
Applicant's new composition with high NCO content permits fast, low viscosity systems,
and can be sprayed at 100% solids with no solvents required. This invention is based on
an NCO content of about 7 to 30, preferred NCO content of 9 to 18, and most preferred
NCO content of 10 to 16. (3) Existing earlier moisture cured systems typically were
forrn~ ted at an index of about 200, whereas this invention utilizes a much lower index.
Broadly it should be an index of about 100 to 160, preferably an index of 100 to 140, and
most preferably an index of about 105 to 130.
Description Of The Invention
Broadly stated this invention involves a new one-component polyurea coating
composition which is curable at ambient temperature and comprises, (a) a
quasi-prepolymer isocyanate, having an NCO content of about 7 to about 30, (b) a
polyamine resin component in the form of a Schiff base blocked amine dispersed
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CA 02242132 1998-06-30
throughout the isocyanate, said composition being formulated at an index between about
100 to 160.
When a diamine is used as the polyamine resin, the diamine may be de~med
as a polyoxyalkylene (li~min~. One group of appropriate polyoxyalkylene ~i~mines that
may be used are those sold by Huntsm~n Corporation as JEFFAMINE~ D-Series products
having the formula:
H2N-CI H-CH2- [-O-CI H2-CH],r-NH2
R' R'
wherein R' independently represents hydrogen or methyl and x is a number having an
average value of about 1 to about 60.
Representative products having this structural formula include
polyoxypropylene diamines with the structure above where x has the following values:
x = 2 to 3 for JEFFAMINE~ D-230
x = 5 to 6 for JEFFAMINE~ D-400
x = ~ 33 for JEFFAMINE~ D-2000 and
x = ~ 60 for JEFFAMINE~ D-4000
This invention works equally well with the polyoxyalkylene amines in
conjunction with both aromatic and cycloaliphatic diamine cross-linkers. Diethyltoluene
diamine (DETDA or ETHACURE~9 l00) and Di(methylthioether)toluene diamine
(ETHACURE~ 300) are examples of aromatic based materials, while isophorone diamine
(VESTANAT~ IPD), 1,4-diaminocyclohexane and 1,2-diaminocyclohexane are examples
of cycloaliphatic (li~min~s. Combinations of high and low molecular weight difunctional
and trifunctional polyoxyalkylene amines (JEFFAMINE~9 D-230, D-400, D-2000, D-4000,
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CA 02242132 1998-06-30
T-403, T-3000 and T-5000) can also be used alone. It has been discovered that
combinations of (li~min~s and triamines are also usable.
When a triamine is used as the polyamine resin, the triamine may be defined
as a polyoxyalkylene triamine. One group of such triamines is shown by the formula:
H2C-(O-CH2- ~Cl H)l-NH2
R'
H-f-(O-CH2-CI H)y-NH2
H2C-(O-CH2- ICH)z~NH2
(where -- x + y+ z = 3~70)
And, x + y + z = ~40-50 for JEFFAMINE T-3000;
x + y + z = ~ 70-80 for JEFFAMINE T-5000
For T-403 (Hnn~m,-n Triamine 403) x + y + z = 5.3
H2C-(O-CH2- ICH)r-NH,
R'
CH3-CH2- I (O_CH2_Cl H)y~NH2
H2C-(O- CH2- CH) - NH2
In order to further illustrate the invention, the following examples are
provided. It is to be understood, however, that the examples are for illustrative purposes
and are not intended to be limiting of the scope of the invention as set forth in the
subjoined claims.
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I~XAMPI,E I
Coating system was prepared by blending 100 parts of "A" component quasi-
prepolymer A 444 (see Glossary description hereinafter) with 133 parts of "B" component
which was prepared by addition reaction of isobutyraldehyde to the two ~ mines and one
triamine to produce a Schiff base (complexed, blocked amine). The water liberated in that
reaction was stripped by vacuum azeotropic distillation. Balance of the "B" formula was
then added and blended into the anhydrous Schiff base.
Following is the "B" formula for example I coating system (in parts by
weight) (see Glossary, which appears later herein, for description of chemicals used).
JEFFAMINE~ D-2000 48.46
JEFFAMINE~ T-5000 12.46
ETHACURE~9 100 16.00
ISOBUTYRALDEHYDE 17.00
PIGMENT 25.00
BAYLITH~ L PASTE 12.00
SILQUEST~9 A 187 (from O.S.I. Co.) 0.50
BYK~9 A501 0.50
BYK~9 320 0.75
METACURE~ T-12 1.00
TOTAL 133.67
Viscosity of the resulting coating system was four hundred fifty centipoise
at room temperature (75~F). Several 3 x 6 inch steel panels were brush coated to a
thickness of approximately .005 inches. The coatings were allowed to cure by atmospheric
moisture. The surfaces became dry to touch in seventy five minutes and hard overnight.
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CA 02242132 1998-06-30
Example II coating system "B" component was prepared by the same method
as example I coating system "B" component described above. Example III through
example XV coating system "B" components were formulated using the commercially
available Schiff bases itemized below on the following pages.
There are advantages of preparing proprietary Schiff bases. A full and
continuous range of blocked amine equivalent weight products is possible by complexing
different ratios of the various molecular weight polyoxyalkylene amines and low molecular
weight aromatic or aliphatic amine cross-linkers with isobutyraldehyde.
Properly formulated combinations will function as single curatives that
produce desired properties in cured elastomers, handling, processing, curing profiles and
cured product physical properties can be maximized with various amine component
combinations.
Currently, there are a very limited number of Schiff bases commercially
available. They all have similar, low equivalent weights. Formulating concessions are
required when using them that are not necessary when high equivalent weight versions are
incorporated. They do, however, work when properly incorporated as is demonstrated by
the example formulas herein.
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CA 02242132 1998-06-30
The following tabulated examples were all prepared according to this
invention.
Polyurea One-Component (2 K) Co~ting
EXAMPLES II III IV V VI VII VIII IX X
Isocyanate A Component
POLYARMOR0 A444 IOO. --- --- 140. 140. 115.115. lOO. ---
POLYARMOR0 CF-60 A --- lOO. IOO. --- --- --- --- --- ---
MONDUR0 ML --- --- --- --- --- --- --- --- lOO.
Resin B Component
VESTAMIN0 A-139 --- 30.3 30.3 49.7 49.7 49.749.7 32.72 112.DESMOPHEN0 XP-7069E --- --- --- --- --- --- --- --- ---
DESMOPHEN0 XP-7076 --- --- --- --- --- --- --- --- ---
DESMOPHEN0 XP-7071E --- --- --- --- --- --- --- --- ---
JEFFOX0 PPG 2000 --- 30.3 30.3 10.85 9.85 13.312.6 --- ---
JEFFAMINE0 D-2000 48.75 --- --- --- --- --- --- --- ---
JEFFAMINE0 T-5000 --- --- --- --- --- --- --- --- ---
ETHACURE0 lOO 17.93 --- --- --- --- --- --- --- ---
UNILINK0 4200 2.25 --- --- --- --- --- --- --- ---
PIGMENT 25. 25. 25. 25. 25. 25. 25. 9.8 ---
BAYLITH0 L PASTE 12. 11.65 11.15 12.7 12.7 --- 12.7 --- ---
BAYLITH0 L POWDER --- --- --- --- --- 12. --- --- ---
SILQUEST A-187 0.5 0.5 0.5 0.5 0 5 --- --- ---
BYK0 A501 0.5 0.5 0.5 0.5 0.5 0.75
BYK0 052 --- --- --- --- --- --- --- 0.75
BYK0 320 0.75 0.75 0.75 0.75 0.75 --- --
JEFFCAT0 DMDEE --- --- 1.5 --- l.O --- --- --- ---
METACURE0 T-12 0.5 l.O --- --- --- --- --- --- ---
PTSI ---
ISOBUTYRALDEHYDE 17.0 --- --- --- --- --- -- --- ---
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CA 02242132 1998-06-30
The following tabulated examples were all prepared according to this
invention.
Polyurea One-Component (2 K) Coating
EXAMPLES XI XII XIII XIV XV
Isocyanate A Component
POLYARMOR0 A444 --- --- 140. --- ---
POLYARMOR0 CF-60 A --- IOO. --- --- ---
POLYARMOR0 A-490 l lO. --- --- 140. ---
VESTANAT0 IPDI --- --- --- --- lOO .
MONDUR0 ML --- --- ---
Resin B Component
VESTAMIN0 A-139 --- --- --- --- lOO.
DESMOPHEN0 XP-7069E --- 34.4 56.4 --- ---
DESMOPHEN0 XP-7076 112.3 --- --- --- ---
DESMOPHEN0 XP-7071 E --- --- --- 33.2 ---
JEFFOX0 PPG 2000 --- 26.2 9.85 10.85 ---
JEFFAMINE0 D-2000 --- --- --- --- ---
JEFFAMINE0 T-5000 --- --- --- --- ---
ETHACURE0 lOO --- --- ---
UNILINK0 4200 --- --- --- --- ---
PIGMENT --- 25. 25. 25. ---
BAYLITH0 L PASTE --- 11.65 12.7 12. ---
BAYLITH0 L POWDER --- --- --- --- ---
SILQUEST A-187 --- 0.5 0.5 0.5 ---
BYK0 A501 1.04 0.5 0.5 0.5 ---
BYK0 052 1.04 --- --- ---
BYK0 320 --- 0.75 0.75 0.75
JEFFCAT0 DMDEE --- --- I .O --
METACURE0 T-12 --- I.O --- l .O ---
PTSI --- --- --- ---
ISOBUTYRALDEHYDE --- -- --- --- ---
Coated specimens were made on 3 x 6 inch steel panels for each of the fifteen example
formulas. A small batch of each formulas was produced and brush applied to the steel
panels to a thickness of approximately .005 inches. All of the batches and specimens were
made during the same day, thus providing common curing conditions for each formula.
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CA 02242132 1998-06-30
Temperature during the trial was 70~F and relative humidity was 40%. Tack free time
along with general observations were recorded for each formula. The information is
tabulated below.
TACK FREE
FORMULA TIME (min.) OBSERVATIONS
Decent film. Smooth. Relatively short pot life.
II 54 Excellent film. Low elongation. Not brittle.
III 40 Excellent film. High elongation. Pot life > 8 hours.
IV -- Cured well. Slightly brittle. Epoxy-like.
V 42 Brushed very well. Good film. Pot life > 8 hours.
VI 18 High gloss. Good film.
VII 50 Pot life > 8 hours.
VIII 45 Cured well. Surface rough and pitted.
IX 20 Good film.
X 25 Good film. Smooth. Fairly brittle. Epoxy-like.
XI 38 Some exotherm on blending. Slightly milky film. Smooth.
XII 38 Quite brittle. Smooth.
XIII 34 Good film. Smooth. Brushed well.
XIV 40 Good film. Smooth. High gloss.
XV 38 Good film. Slightly brittle. Epoxy-like.
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CA 02242132 1998-06-30
Description Of Quasi-Prepolymers
(Parts By Weight)
POLYARMOR~ CF-60A 444A 462A 490A
Modified MDI 60.0
Liquid Uretonimine-modified
Methylene Diisocyanate (MDI) 49 4 44 0
Isopllorone Diisocyanate 45 .0
2000 MW Polypropylene Glycol 40.6 40.0 56.0
Polyoxyalkylene Diamine 45 .0
Propylene Carbonate 10.0 10.0
Totals 100.0100.0 100.0 100.0
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CA 02242132 1998-06-30
GLOSSARY
POLYARMOR~ CF-60 A An aliphatic quasi-prepolymer available from Visuron
Technologies, Inc. (Bay City, Michigan).
POLYARMOR~ A-444 An aromatic quasi-prepolymer available from Visuron
Technologies, Inc. (Bay City, Michigan).
POLYARMOR~9 A-462 An aromatic quasi-prepolymer available from Visuron
Technologies, Inc. (Bay City, Michigan).
POLYARMOR~ A-490 An aromatic quasi-prepolymer available from Visuron
Technologies, Inc. (Bay City, Michigan).
VESTANAT~ IPDI Isophorone diisocyanate available from Huls America
Co.
VESTAMIN~ A-139 A Schiff Base available from Huls America Co.
~ESMOPHEN~ XP-7069E A Schiff Base available from Bayer Co.
~ESMOrIIl~N~ Xr-7071E A Scllit'f Base available from Bayer Co.
~ESMOPHENa~ XP-7076E A Schiff Base available from Bayer Co.
MONDUR~ ML A liquid uretonimine-modified methylene diisocyanate
product available from Bayer Co.
JEFFAMINE~ D-2000 An amine-terminated polyoxypropylene diol of 2000molecular weight available from H lntcm:~n Corporation.
JEFFAMINE~ T-5000 An amine-terminated polyoxypropylene triol of 5000
molecular weight available from Hnnt~m~n Corporation.
JEFFOX'~9 PPG-2000 A propylene glycol product have a molecular weight of
2000 from Hunt~m~n Corporation.
ETHACUREX 100 A diethyltolunediamine product from Albemarle Co.
UNILINK~ 4200 An N, N'-Bis(alkyl)methylenetli"niline product from
UOP, Inc.
BAYLITH~ L PASTE A molecular sieve in paste form available from Bayer
Co.
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CA 02242132 1998-06-30
BAYLITH~ L POWDER A molecular sieve in powder form available from Bayer
Co.
SILQUEST~ A-187 Gamrna-Glycidoxypropyltrimethoxy silane. Coupling Agent. Available from O.S.I. Specialties, Inc.
BYK~ A501 Silicone free defoamer from BYK Chemie Co.
BYKQ9 052 Silicone free defoamer from BYK Chemie Co.
BYK~9 320 Silicone free defoamer from BYK Chemie Co.
JEFFCAT~ DMDEE Dimorpholino-dethylether. Amine catalyst for moisture
cure. Available from Huntsman Corporation.
METACURE~T-12 Dibutyltindilaurate. Gellation catalyst. Available
from Air Products Co.
PTSI p-Toluenesulfonylisocyanate. Monofunctionalmoisture
scavenger. A product of VanChem, Inc.
JEFFSOL~9 PC Propylene carbonate available Hunstman Corporation.
ISOBUTYRALDEHYDE Available from Eastman Chemical Co.
Pi~nents
Ti-Pure3 R-900 Titanium dioxide available from E.I. du Pont de
Nemours, Co.
RAVEN~ 1020 Carbon black available from Columbia Chemicals Co.
Pigment Dispersions Pigments of various colors dispersed in high molecular
weight polyol. Available from Plasticolors, Inc.
The volumetric ratio of the "A" isocyanate component and "B" resin
component as shown in the examples above should be from about 75 to 25 or reverse;
more preferably 60 to 40 or reverse; most preferably 50:50.
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CA 02242132 1998-06-30
Extended shelf life studies of several versions of example formula III ("A"
and "B" components blended) have been made. It has been observed that the viscosity of
the coating in sealed, nitrogen blanketed containers has not increased materially. The
curing profile, appearance and physical properties of coated specimens is about the same
after 90 days as for freshly blended material and coated samples. Accordingly, it is
believed that coatings of this invention will be suitable for true one component, single
container (lK) shipment and delivery. (lK = one component).
Studies have been made to accelerate the cure profile of the coatings made
under this invention. It has been found that "tack-free time" can be dramatically reduced
by exposure to increased humidity. As seen with the example formulas, tack-free time
ranging from about thirty to seventy five minutes were achieved at 70~F/40% relative
humidity. Separate trials using example formula III coated specimens were exposed to the
following conditions: Water mist over the coating at room temperature decreased tack-free
time by about 50%, misting with water at 120~F deceased the tack-free time by about 66%
and, finally placing coated specimens of Formula III in atmospheric steam at 150-175~F
resulted in tack-free times as low as sixty seconds. While the extremely fast sixty second
tack-free samples exhibited some deterioration, slightly slower three minute tack-free
samples were quite good and ten minute tack-free samples were excellent. The benefits
are highly advantageous for production coating applications where line speed matched
curing profiles are necessary. Similarly, the benefits are highly advantageous for
contracting coating applications where turn around and return to use time can be reduced.
These accelerated techniques are not possible with prior moisture cured urethanes.
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CA 02242132 1998-06-30
presence of the excess moisture and resulting faster cure rate previously resulted in
substantial coating deterioration in the form of bubbles, blisters and pinholes.
The information herein is provided to describe an important embodiment of
the one component polyurea technology of this invention. Polyurea is increasingly being
used as a concrete floor sealant coating to compete with epoxy, urethanes and other current
offerings. Warehouse, shop, office mechanical room and aircraft hanger floors are
examples of where such coatings can be highly useful. Interior floor sealing applications
such as these are specified primarily to provide attractive floors, seal the concrete against
wear and concrete dust, preclude moisture and chemical cont~min~nt intrusion, provide
markings such as pedestrian aisle perimeters, and to allow for periodic washing for
cleanliness.
Similarly, the coatings of this invention are highly useful in parking deck
coating applications. Parking decks are seal coated to protect against weather
deterioration, primarily to prohibit intrusion of water and chlorides into the concrete.
They are sealed with an aggregate course included in the upper layer to enhance the
wearability of the surface against vehicular tire wear and pedestrian scuffing. Primary
reasons for polyurea use are: Quick turn-around and return to use, durability of the cured
coating, and cost competitiveness.
Plural component polyurea, however, is substantially limited for the above
uses, especially for inside applications, due to the overspray that is a by-product of the
high pressure, high velocity material discharge from the spray gun. Fume and misting
containment requirements are extensive. Masking and isolation wall preparations generally
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CA 02242132 1998-06-30
exceed the actual coating timing. Frequently, such operations are unacceptable, such as
in a hospital environment where the fugitive odors and misting are prohibitive.
Exterior installations, such as parking deck coatings are also plagued with
overspray, which becomes airborne and coats automobiles and structures. Meticulous
attention needs to be given to the wind conditions and direction with corresponding
screening utilized. Experience on many jobs with contractors has proven that adequate
protection is only seldomly used.
Several approaches have been attempted in the past to overcome these prior
problems and difficulties. (1) Topcoat the polyurea seal coat with epoxy. Poor solution
since epoxy is not color-fast. It is also brittle and is well known for cracking and crazing.
(2) Topcoat the polyurea seal coat with commercial moisture cured pigmented urethane or
clearcoat. The urethanes are color-fast, have decent elongation, but also have solvents and
have not been very well received by end users. The solvents generate unacceptable fumes.
(3) Several end users have tried to topcoat aromatic polyurea seal coat with aliphatic
polyurea. There are, however, serious deficiencies: The overspray and fumes are still
present; cleaning the spray machine and hoses and the changeover from aromatic to
aliphatic is very time consuming and expensive, and; the logistics of when and at what
stage of the job to changeover are highly problematical.
This new one component polyurea of this invention solves all of the above
over coating problems. (1) It has sufficient working time. It can be brush, roller,
squeegee or spray applied. When airless sprayed, the overspray is minim:~l. When coated
out by the other methods the overspray is totally elimin~ted. The odors emitted are
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CA 02242132 1998-06-30
reasonable regardless of tlle application metho(l. (2) For interior applications, the base
sealing coat could be non-spray applied one component aromatic polyurea. Upon sufficient
cure, that could be followed with the topcoat of aliphatic one component, also by non-
spray methods. (3) For exterior applications (and those interior permitting) the seal coat
could be plural component aromatic polyurea sprayed followed within minutes with the one
component aliphatic airless sprayed from a separate pump by another operator (including
aggregate, if required). The topcoat could either be pigmented of clearcoat which provides
depth.
The spectrum of suitable embodiments for the coatings of this invention is
very large. These coatings are ideal as protective barriers for steel engineering structures
such as buildings, storage tanks and bridges as well as for mobile vessels like ship hulls,
railcars~ trucks and automobiles and civil engineering -- road marking coatings. They are
also excellent sealants for all types of masonry surfaces in addition to flooring cited above.
Also, wood sealing is very cost effective and provides protection and aesthetic value in al
types of applications.
While it will be apparent that the preferred embodiments of the invention
disclosed above are well calculated to fulfill the objects, benefits and advantages of the
invention, it will be appreciated that the invention is susceptible to modification, variation
and change without departing from the proper scope or fair meaning of the subjoined
claims.
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