U.S. patent application number 12/162251 was filed with the patent office on 2009-08-27 for multi-component coating method for porous substrates.
This patent application is currently assigned to Valspar Sourcing, Inc.. Invention is credited to Stephen M. Carlson, Kevin W. Evanson, Brian L. Marty, Andrew Ubel.
Application Number | 20090214791 12/162251 |
Document ID | / |
Family ID | 39033437 |
Filed Date | 2009-08-27 |
United States Patent
Application |
20090214791 |
Kind Code |
A1 |
Evanson; Kevin W. ; et
al. |
August 27, 2009 |
MULTI-COMPONENT COATING METHOD FOR POROUS SUBSTRATES
Abstract
The disclosure relates to a coating method including the steps
of providing a multi-component coating composition including two or
more components, applying each component to a porous substrate,
mixing each component with at least one other component thereby
causing at least two components to undergo a chemical reaction.
Inventors: |
Evanson; Kevin W.; (Maple
Grove, MN) ; Marty; Brian L.; (Oakdale, MN) ;
Carlson; Stephen M.; (Burnsville, MN) ; Ubel;
Andrew; (St. Paul, MN) |
Correspondence
Address: |
SHUMAKER & SIEFFERT, P. A.
1625 RADIO DRIVE, SUITE 300
WOODBURY
MN
55125
US
|
Assignee: |
Valspar Sourcing, Inc.
Minneapolis
MN
|
Family ID: |
39033437 |
Appl. No.: |
12/162251 |
Filed: |
January 30, 2007 |
PCT Filed: |
January 30, 2007 |
PCT NO: |
PCT/US2007/002347 |
371 Date: |
January 7, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60764044 |
Jan 31, 2006 |
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60773482 |
Feb 15, 2006 |
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60802185 |
May 19, 2006 |
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60802186 |
May 19, 2006 |
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60819505 |
Jul 7, 2006 |
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Current U.S.
Class: |
427/294 ;
427/333 |
Current CPC
Class: |
C04B 41/71 20130101;
C04B 41/009 20130101; B28B 11/04 20130101; C04B 41/52 20130101;
C04B 41/52 20130101; C04B 41/488 20130101; C04B 41/009 20130101;
C04B 28/14 20130101; C04B 41/009 20130101; C04B 20/0048 20130101;
C04B 28/02 20130101 |
Class at
Publication: |
427/294 ;
427/333 |
International
Class: |
C04B 41/52 20060101
C04B041/52; B05D 3/10 20060101 B05D003/10; C04B 41/46 20060101
C04B041/46 |
Claims
1. A method comprising: providing a multi-component coating
composition including two or more components; introducing each
component at a rate corresponding to an application rate for each
component; applying each component to a surface of a porous
substrate at the application rate; mixing each component with at
least one other component, thereby causing at least two components
to undergo a chemical reaction.
2. The method of claim 1, further comprising allowing at least some
of the components to penetrate into the porous substrate.
3. The method of claim 1, wherein the porous substrate is one of a
fibrous cement substrate and a gypsum wall board.
4. The method of claim 1, wherein the porous substrate is a fibrous
cement substrate.
5. The method of claim 1, wherein each component in the coating
composition is in a separate container before the component is
applied to the surface.
6. The method of claim 1, wherein the multi-component coating
composition comprises at least a first component and a second
component, wherein the first component and second component
comprise, respectively: an amino-functional compound and an
oxirane-functional compound; an amide-functional compound and an
oxirane-functional compound an amino-functional compound and an
isocyanate compound; an amino-functional compound and a
(meth)acrylic functional compound; a hydroxyl-functional compound
and an isocyanate compound; a hydroxyl-functional compound and a
melamine compound; an acid-functional compound and a melamine
compound.
7. The method of claim 1, wherein the multi-component coating
composition comprises at least a first component comprising an
amino-functional chemical compound, and at least a second component
comprising an oxirane-functional chemical compound.
8. The method of claim 1, wherein the multi-component coating
composition further comprises at least one additive selected from
the group consisting of a catalyst, a wetting agent, or a rheology
control agent.
9. The method of claim 1, wherein the multi-component coating
composition comprises at least one carrier liquid.
10. The method of claim 1, wherein the porous substrate is a
fibrous cement substrate comprising a sheet having a plurality of
edges adjoining a first major surface, and a second major surface
adjoining the edges opposite the first major surface.
11. The method of claim 10, wherein each component is applied to at
least the first major surface and at least one of the edges.
12. The method of claim 11, wherein each component is further
applied to the second major surface and each of the edges.
13. The method of claim 1, wherein the porous substrate is a
fibrous cement substrate, and wherein a first component of the
multi-component coating composition is applied to a surface of the
substrate before a second component of the multi-component coating
composition is applied to the surface of the substrate, and wherein
a first component penetration time is allowed to elapse before
applying the second component.
14. The method of claim 13, wherein the first component comprises
an amino-functional chemical compound, and wherein the second
component comprises an oxirane-functional chemical compound.
15. The method of claim 1, further comprising removing at least a
portion of the multi-component coating composition from a surface
of the substrate.
16. The method of claim 15, wherein removing at least a portion of
the multi-component coating composition from a surface of the
substrate takes place after allowing at least some of the
components to penetrate into the substrate.
17. The method of claim 15, further comprising applying at least a
portion of the multi-component coating composition removed from the
surface of the substrate to a surface of a second substrate.
18. The method of claim 17, further comprising mixing at least a
portion of the multi-component coating composition removed from the
surface of the substrate with at least a portion of the
multi-component coating composition not previously applied to the
substrate to form a recycled coating mixture before applying the
recycled coating mixture to a surface of a second substrate.
19. The method of claim 15, wherein removing at least a portion of
the multi-component coating composition from the surface of the
substrate comprises directing a gas stream against at least a
portion of the coated surface to remove at least a portion of the
multi-component coating composition.
20. The method of claim 1, wherein applying each component to the
substrate comprises coating the component onto a surface of the
substrate using one or more of brush coating, knife coating, direct
roll coating, reverse roll coating, spray coating, extrusion die
coating, curtain coating, flood coating and vacuum coating the
porous substrate is a fibrous cement substrate.
21. The method of claim 1, wherein mixing takes place before
applying each component to the substrate.
22. The method of claim 21, wherein mixing takes place in an
in-line mixer.
23. The method of claim 1, wherein mixing occurs upon applying each
component to the substrate.
24. The method of claim 1, wherein the multi-component coating
composition is applied to the substrate to obtain a dry coating
weight of from about 1 g/m.sup.2 to about 40 g/m.sup.2.
25. The method of claim 1, wherein the substrate is a fibrous
cement substrate, and wherein the substrate exhibits a water
droplet penetration time of from about 1 second to about 15
seconds.
26. A method comprising: providing a multi-component coating
composition including at least a first component comprising an
amino-functional polymer and a second component comprising an
oxirane-functional polymer; applying each component to a fibrous
cement substrate; mixing the first component with at least the
second component, thereby forming a reacting mixture wherein the
first and second components undergo a chemical reaction; and
allowing at least some of the reacting mixture to penetrate into
the fibrous cement substrate.
27. The method of claim 26, wherein each component is contained in
a separate container prior the applying step.
28. A method comprising: providing a multi-component coating
composition comprising at least a first component comprising an
amino-functional compound and a second component comprising an
oxirane-functional compound, wherein each component is contained in
a separate container; applying each component to a porous
substrate; mixing the first component with at least the second
component on a surface of the porous substrate, thereby forming a
reacting mixture wherein the first and second components undergo a
chemical reaction; and allowing at least some of the reacting
mixture to penetrate into the surface of the porous substrate.
29. The method of claim 28, wherein the porous substrate comprises
a sheet having a plurality of edge surfaces adjoining a first major
surface, and a second major surface adjoining the edge surfaces
opposite the first major surface, wherein each component is applied
to at least the first major surface and the plurality of edges.
30. The method of claim 28, wherein the reaction is a cross-linking
reaction.
Description
TECHNICAL FIELD
[0001] This disclosure relates to methods for applying a
multi-component coating composition to a porous substrate.
BACKGROUND
[0002] Porous materials such as, for example, fiber reinforced
cement materials, gypsum wall board and the like, are increasingly
being used as internal and external cladding panels in a variety of
building construction applications. These porous materials have
good fire resistance and barrier characteristics, and may be
produced at a reasonable cost.
[0003] Fiber-reinforced cement materials may be manufactured by
applying a finish to one or more surfaces of the panel. The finish
may be a coating that prevents or reduces water penetration into
porous surfaces of the panel. The coating is typically applied to a
surface of the fibrous cement material in a liquid state, but
subsequently undergoes a chemical transformation to a solid-like
cured state. Two-part reactive systems, for example two-part epoxy
resins that form a reactive mixture upon combining a base component
with an epoxy component, have been used as coatings for fiber
reinforced cement materials.
[0004] It is particularly desirable to apply the coating to at
least the exterior face and edges of the fibrous cement panel to
prevent water penetration and/or provide improved adhesion to
additional protective and decorative coatings. Various coating
methods, for example, spray coating and sponge-roll coating, have
been used for applying coatings to the surfaces of fiber reinforced
cement materials.
[0005] Unfortunately, multi-part reactive coating systems, such as
two-part epoxy resins, have a limited pot life. After the
components are combined to initiate the curing reaction and form a
reactive mixture, if the mixture is not applied to a substrate
within a relatively short period of time the mixture must be
discarded. This wastes coating materials and requires extensive
coater down time to clean the coating fluid delivery system,
particularly if a coating line stoppage occurs. In addition, once
the materials are mixed and the curing reaction begins, the
properties of the mixture are constantly changing, so control of
process variables in the coating process may be difficult.
SUMMARY
[0006] In general, this disclosure relates to coating methods for
applying a multi-component coating composition to a porous
substrate, for example, a fibrous cement substrate. This disclosure
further relates to coating methods for applying to porous
substrates a multi-component coating composition capable of
undergoing a chemical curing reaction.
[0007] In one embodiment, this disclosure is directed to a method
including providing a multi-component coating composition including
two or more components, applying each component to a porous
substrate, mixing each component with at least one other component,
thereby causing at least two components to undergo a chemical
reaction, and allowing at least some of the components to penetrate
into the substrate.
[0008] In other embodiments, mixing takes place before applying
each component to the porous substrate. In other embodiments,
mixing occurs upon applying each component to the porous substrate.
In further exemplary embodiments, the method includes the step of
removing at least a portion of the applied multi-component coating
composition from a surface of the porous substrate.
[0009] In certain exemplary embodiments, the porous substrate may
be a fibrous cement substrate. In some embodiments the fibrous
cement substrate may be a sheet having a plurality of edges
adjoining a first major surface, and a second major surface
adjoining the edges opposite the first major surface. In some
embodiments, each component is applied to at least the first major
surface and at least one of the edges of the substrate sheet. In
other exemplary embodiments, each component is also applied to the
second major surface and each of the edges.
[0010] In certain embodiments, the first component may include an
amino-functional chemical compound, and the second component may
include an oxirane-functional chemical compound.
[0011] In other embodiments, this disclosure is directed to a
method including providing a multi-component coating composition
including at least a first amino-functional polymer component and a
second oxirane-functional polymer component contained in separate
containers, applying each component to a fibrous cement substrate,
mixing the first component with at least the second component to
form a reacting mixture, and allowing at least some of the reacting
mixture to penetrate into the fibrous cement substrate.
[0012] In further embodiments, this disclosure is directed to a
method including providing a multi-component coating composition
including at least a first amino-functional compound and a second
oxirane-functional compound contained in separate containers,
applying each component to a porous substrate, mixing the first
component with at least the second component, thereby forming a
reacting mixture undergoing a chemical reaction, and allowing at
least some of the reacting mixture to penetrate into the porous
substrate.
[0013] According to some aspects of the invention, a method for
coating a fibrous cement substrate may provide certain advantages,
including longer pot life of reactive coating components, less
waste of coating materials, reduced down-time for cleaning of the
coating fluid delivery system, and reduced coating materials cost.
Coating methods according to some embodiments of the present
invention may also permit more uniform coating of the edge surfaces
of fibrous cement panels, improved wet and dry adhesion of the
coated components on the porous substrate, and higher throughput of
fibrous cement panels in a continuous coating line, thereby
increasing productivity and reducing cost.
[0014] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages of the invention will be
apparent from the description and drawings, and from the
claims.
BRIEF DESCRIPTION OF DRAWINGS
[0015] FIG. 1 is a schematic side view diagram illustrating an
exemplary method of coating a fibrous cement substrate according to
an embodiment of the present invention.
[0016] FIG. 2 is a schematic side view diagram illustrating an
exemplary method of coating a fibrous cement substrate according to
another embodiment of the present invention.
[0017] FIG. 3 is a schematic side view diagram illustrating an
exemplary method of coating a fibrous cement substrate according to
an additional embodiment of the present invention.
[0018] FIG. 4 is a schematic side view diagram illustrating an
exemplary method of coating a fibrous cement substrate according to
a further embodiment of the present invention.
[0019] FIG. 5 is a schematic side view diagram illustrating an
exemplary method of coating a fibrous cement substrate according to
another embodiment of the present invention.
DETAILED DESCRIPTION
[0020] The disclosure relates generally to methods for applying a
coating to a substrate that is porous and/or hydrophilic. Any
porous material is suitable for use as a substrate, but the
following description will focus on porous materials commonly used
in the building and construction industry, for example, a fibrous
cement substrate (FCS) or a gypsum wall board.
[0021] For example, the substrate may be a low density fibrous
cement board having a porosity of about 40%-80% by volume, a medium
density fibrous cement board having a porosity of about 20-40% by
volume, or a high density/compressed fibrous cement board having a
porosity of about 2%-20% by volume. Porosity and/or hydrophilicity
may be determined using a direct measurement, such as porosimetry,
or may be estimated using a qualitative test method such as a water
droplet penetration measurement (e.g. the water penetration test
described below). As will be described in greater detail below, the
porosity and/or hydrophilicity of the substrate may also be
modified by mechanical or chemical treatment.
[0022] The substrate is typically in the form of a generally
polygonal sheet, panel or slab, for example, a generally
rectangular sheet. In certain exemplary embodiments, the fibrous
cement substrate may be a sheet having a plurality of edges
adjoining a first major surface (e.g. an exterior face), and a
second major surface (e.g. an interior face) adjoining the edges
opposite the first major surface.
[0023] The fibrous cement substrate sheets may be produced using a
wide variety of processes. For example, the Hatschek process uses a
series of rotating drum sieves to deposit sequential layers of
de-watered slurry onto an absorbent conveyer and accumulate them on
a size roll until the desired sheet thickness has been achieved.
However, the green sheets can also be produced using other known
methods such as extrusion, casting, molding, Mazza, Magnani,
Fourdrinier and roll press processes. The fibrous cement substrate
may be sanded, machined, extruded, molded or otherwise formed into
any desired shape. The substrate may be fully cured, partially
cured or in the uncured "green" state.
[0024] A variety of different fibrous cement compositions and
methods of making fibrous cement compositions are described in PCT
Applications WO 0168547 and WO9845222. The fibrous cement
composition used to form the fibrous cement substrate generally
includes a plurality of fibers dispersed in an inorganic binder.
The binder may include ordinary Portland cement type I but may also
include other inorganic binders such as gypsum, geopolymer, or
other inorganic cements. Suitable fibers include various forms of
cellulose fibers, such as bleached or unbleached Kraft pulp.
[0025] In particular, a fiber derived from cellulose wood pulp may
be used in the fibrous cement composition. Other examples of
suitable fibers are ceramic fiber, glass fiber, mineral wool, steel
fiber, and synthetic polymer fibers such as polyamides, polyester,
polypropylene, polymethylpentene, polyacrylonitrile,
polyacrylamide, viscose, nylon, PVC, PVA, rayon, glass ceramic,
carbon, or any mixtures thereof. The fibers may also include
cellulose fibers with hydrophilic treatments, hydrophobic
treatments, biocide treatments, or the like, such as those
disclosed in PCT Patent Applications WO 0228796 and WO 0228795.
[0026] The fibrous cement composition may also include an
aggregate. The aggregate may include milled quartz, amorphous
silica, perlite, vermiculite, synthetic calcium silicate hydrate,
diatomaceous earth, rice hull ash, fly ash, bottom ash, blast
furnace slag, granulated slag, steel slag, mineral oxides, mineral
hydroxides, clays, magnesite, or dolomite, polymeric beads, metal
oxides and hydroxides, or mixtures thereof.
[0027] Additional additives may be optionally incorporated into the
fibrous cement composition including but not limited to density
modifiers, dispersing agents, silica fume, geothermal silica, fire
retardant, viscosity modifiers, thickeners, pigments, colorants,
dispersants, foaming agents, flocculating agents, water-proofing
agents, organic density modifiers, aluminum powder, kaolin, alumina
trihydrate, mica, metakaolin, calcium carbonate, wollastonite,
polymeric resin emulsions, or mixtures thereof.
[0028] According to one embodiment of the present invention, a
coating is applied to a porous substrate using a method including
the steps of providing a multi-component coating composition
including two or more components that are preferably contained in
separate containers. Each component is applied to a porous
substrate and mixed with at least one other component, which causes
the at least two components to undergo a chemical reaction. At
least some of the components preferably penetrate into the porous
substrate and form a coating.
[0029] The multi-component composition may include at least a first
component and a second component, but the composition may also
include additional components. The multi-component composition may
be a primer, a sealer a topcoat, or other coating composition for
application to a fibrous cement substrate. Exemplary coating
compositions of the present invention may be used in place of or in
addition to prior art "sealers" and "primers." However, the
compositions of the present invention may not fit neatly into
either category per se and such terms should not be limiting.
[0030] In certain exemplary embodiments, the first and second
components undergo a chemical reaction with each other or with
other components in the multi-component composition upon mixing, as
described below.
[0031] The first and second components in the multi-component
coating composition may vary widely depending on the intended
applications, and may include, respectively:
[0032] an amino-functional compound and an oxirane-functional
compound;
[0033] an amide functional compound and an oxirane functional
compound;
[0034] an amino-functional compound and an isocyanate compound;
[0035] an amino-functional compound and a (meth)acrylic functional
compound;
[0036] a hydroxyl-functional compound and an isocyanate
compound;
[0037] a hydroxyl-functional compound and a melamine compound;
or
[0038] an acid-functional compound and a melamine compound.
[0039] Functional groups are groups available for curing and/or for
the formation of crosslinks. Preferred amino-functional chemical
compounds are characterized by a molecular structure which includes
at least one group selected from NH and NH.sub.2. Preferred amide
functional compounds include the group RC.dbd.ONH.sub.2. Oxirane
compounds include at least one oxirane functional group, and
(meth)acryl groups refers to compounds having acryl and/or
methacryl functional groups. Isocyanate compounds include a --NCO
radical, while melamine compounds are amino-functional compounds
made from melamine and formaldehyde. While any of these components
may be present in the multi-component coating composition, for
brevity the following description will focus on multi-component
coating compositions including an amino-functional compound as the
first component and an oxirane-functional compound as the second
component.
[0040] The amino-functional chemical compound may be a low
molecular weight molecule (e.g. having a weight average molecular
weight less than about 1000 Daltons), or may be in the form of a
polymer or resin (e.g. having a weight average molecular weight
greater than about 1000 Daltons). In some embodiments, the
amino-functional chemical compound has a plurality of amino groups
and is capable of functioning as a cross-linker.
[0041] Preferred oxirane-functional chemical compounds are
characterized by a molecular structure which includes at least one
oxirane chemical group. The oxirane-functional chemical compound
may be a low molecular weight molecule (e.g. having a weight
average molecular weight less than about 1000 Daltons), or may be
in the form of a polymer or resin (e.g. having a weight average
molecular weight greater than about 1000 Daltons). In some
embodiments, the oxirane-functional chemical compound has a
plurality of oxirane groups and is capable of functioning as a
cross-linker.
[0042] Preferably, the amino-functional chemical compound and/or
the oxirane-functional chemical compound are waterborne, water
reducible or water dispersible two-component epoxy compositions.
Exemplary two-component epoxy compositions include amino-functional
phenolic resins (e.g. benzoguanamine resins), and exemplary
oxirane-functional chemical compounds include bisphenol epoxy
resins, as described in Wicks, Z. W. et al., Organic Coatings
Science and Technology, Vol. 1, Chapter XI, pp. 1162-1187.
[0043] In this embodiment, the application rate of each component
to a porous substrate is determined by the stoichiometric ratio of
oxirane-functionality to amino-functionality, which is generally
controlled by the equivalent weight of each component and the
mixing weight ratio of each component. The application rate is also
determined by substrate morphology and porosity and the desired
application viscosity. The oxirane-functional and amino-functional
components may be applied at differing percent solids (percent
non-volatile material) and/or wet film thicknesses to obtain the
desired mixing weight ratio. Preferred mixing weight ratios
generally vary from about 2:1 to about 1:2, more preferably about
2:1 to about 1:1.2, of oxirane-functional chemical compound to
amino-functional chemical compound.
[0044] The chemical composition of adjacent coating layers may have
an impact on the oxirane/amino mixing weight ratios described
above. For example, functional groups may be included in the
chemical compounds in adjacent coating layers to react with any
excess amine groups which may in some cases allow a larger
proportion of the amino functional compound in the mixture.
[0045] Conventional solvent-based two-component epoxy resin
compositions are highly viscous and tend to have higher emissions
of volatile organic compounds (VOC) than waterborne two-part epoxy
compositions. These compositions may be thinned (e.g. by adding a
carrier liquid to lower the percentage of non-volatile solids and
thereby lower the viscosity. Two-component epoxy compositions may
be classified as liquid, semi-solid and solid, depending on their
molecular weight, which tends to increase in going from liquid to
solid form. Although all three types of two-component epoxies may
be suitable for use according to the present invention, the liquid
and semi-solid types are presently preferred. While not wishing to
be bound by any particular theory, we believe that the liquid and
semi-solid two-component epoxy resin systems permit reasonably high
application solids while maintaining some degree of molecular
mobility to facilitate inter-component diffusion and chemical
reaction.
[0046] The coating compositions may also contain an optional
coalescent and many coalescents are known in the art. The optional
coalescent is preferably a low VOC coalescent such as is described
in U.S. Pat. No. 6,762,230.
[0047] In certain embodiments, one or both of the amino-functional
chemical compound and the oxirane-functional chemical compound may
be chemically blocked to prevent or delay onset of chemical
reaction until a desired time, at which time a stimulus is used to
de-block the components and permit reaction. For example, amine
groups may be blocked to form a ketimene, which can unblock in the
presence of moisture. Alternatively or additionally, the blocked
component may be heated to facilitate unblocking.
[0048] The amino-functional chemical compound and
oxirane-functional chemical compound are further characterized as
being capable of undergoing chemical reaction (e.g. epoxidation)
with at least each other, and optionally with other components
present in the multi-component coating composition. For example,
the multi-component composition may include at least one catalyst,
such as an alcohol or an acid or a base catalyst, suitable for
catalyzing the epoxidation chemical reaction. Other catalysts or
reaction initiators may also be included in the multi-component
coating composition.
[0049] Other additives may be included in the multi-component
composition to alter or improve the application characteristics of
the composition to the fibrous cement substrate. For example, a
wetting agent may be used to adjust the surface tension of one or
more components of the multi-component composition to alter the
wetting characteristics with respect to the fibrous cement
substrate. Non-limiting examples of wetting agents include water
soluble or water miscible non-ionic surfactants exhibiting an
hydrophile-lipophile balance ("HLB") from about 10 to about 20.
[0050] In addition or alternatively, a rheology control agent may
be added to the multi-component composition to alter the flow
and/or leveling characteristics of the composition upon application
to the fibrous cement substrate. For example, a rheology control
agent may be added to one or more of the components of the
multi-component composition to reduce the low shear viscosity of
the composition and thereby improve the leveling and/or penetration
of the component into the porous substrate. Exemplary rheology
control agents include the resin flow modifiers available under the
trade designation MODAFLOW from Cytec Industries, Inc., Charlotte,
N.C., and acrylic leveling agents available under the trade
designations BYK and DISPERBYK from Byk-Chemie, Wesel, Germany.
[0051] In certain embodiments, the multi-component coating
composition may include at least one carrier liquid. The carrier
liquid may be a single chemical compound, but generally the carrier
liquid is selected to be a blend of different chemical compounds.
The carrier liquid may be aqueous, nonaqueous or substantially
nonaqueous. Aqueous carriers include water as a major component,
while substantially nonaqueous carrier liquids do not include water
as a major component. Nonaqueous carrier liquids contain no water
or negligible amounts of water. Preferably, the carrier liquid is
selected to be aqueous or substantially nonaqueous. Suitable
co-solvents used in combination with water in an aqueous or
substantially nonaqueous carrier liquid include water soluble or
water miscible alcohols, ketones, esters, and the like.
Non-limiting examples of carrier liquids include water (which may
include tap water, deionized water, distilled water, and the like),
methanol, acetone, 2-butanone, ethyl acetate, and various glycol
based ethers.
[0052] The carrier liquid constituents and/or the amount of carrier
liquid or the percent of non-volatile material (% NVM) dispersed or
dissolved in the carrier liquid may be adjusted to obtain a
viscosity or surface tension desirable for application of one or
more of the components of the multi-component composition to the
fibrous cement substrate. For certain non-limiting applications, a
suitable weight percentage of non-volatile solids in a component of
the multi-component coating composition may be from about 10% to
about 60%, more preferably from about 15% to about 55% NVM, most
preferably from about 30% to about 50% NVM expressed on a weight
basis.
[0053] Additional or alternative additives may be included in any
or all of the components of the multi-component composition.
Suitable additives for use in coating compositions of the present
invention are described in Koeske et al., Paint and Coatings
Industry, April, 2003, pages 12-86. Typical performance enhancing
additives that may be employed include surface active agents,
pigments, colorants, dyes, surfactants, thickeners, heat
stabilizers, leveling agents, anti-cratering agents, curing
indicators, plasticizers, fillers, sedimentation inhibitors,
ultraviolet-light absorbers, optical brighteners, and the like to
modify properties.
[0054] In some embodiments, the first and second components of the
multi-component composition are mixed together subsequent to
leaving their respective storage containers, typically a closed
holding vessel such as a tank. In certain embodiments, mixing takes
place before applying each component to the fibrous cement
substrate. In certain exemplary embodiments, mixing may take place
in an in-line mixer, for example, those available from Chemineer,
Inc., Andover, Mass., under the trade designation Kenics Static
Mixer.
[0055] Mixing may additionally or alternatively take place upon
application of the first and second components to a surface of the
porous substrate. While not wishing to be bound to any particular
theory, we believe that mixing of the first and second components
may be achieved, for example, by inter-molecular diffusion driven
by concentration gradients, surface tension gradients and/or
thermal gradients between the first and second components upon
mixing and/or application to the porous substrate.
[0056] Various methods may be used for applying the multi-component
coating to the fibrous cement substrate. For example, one or more
of brush coating, knife coating, direct roll coating, reverse roll
coating, spray coating, extrusion die coating, curtain coating,
flood coating and vacuum coating may be used to apply one or more
component of the multi-component coating to the substrate.
[0057] In general, the application of the first, second and
additional optional components of the multi-component composition
may be carried out in any order. However, for sequential
application methods, it is presently preferred that the
amine-functional chemical compound be applied before the
oxirane-functional chemical compound. Currently available data
indicate that this order of application provides superior sealant
performance and better inter-coat adhesion for multi-layer
coatings.
[0058] In one embodiment, the first and second components may be
applied "wet-on-wet." However, depending on the application
technique and substrate characteristics, a drying step may be
included after application of the first, second, or subsequent
components to the porous substrate. While not wishing to be bound
by any particular theory, a drying step may permit the hardening,
curing, or otherwise immobilization of an earlier applied
component, thereby allowing a later applied component to be applied
without contaminating the second component's fluid delivery system.
This may be particularly important in flat-line applications using
curtain coating, flood coating, roll coating, and the like.
[0059] In certain additional embodiments, the first component of
the multi-component coating composition is applied to a surface of
the fibrous cement substrate before a second component of the
multi-component coating composition is applied to the surface, and
a first component penetration time is allowed to elapse before
applying the second component. In certain exemplary embodiments,
the first component applied to a surface of the fibrous cement
substrate includes an amino-functional chemical compound, and the
second component includes an oxirane-functional chemical
compound.
[0060] The desired first component penetration time may be
estimated using a porosity or hydrophilicity test, such as a
droplet penetration test. In one exemplary water droplet
penetration test, a single droplet of deionized water (as an
assessment of the porosity and/or hydrophilicity of the porous
substrate to be coated) or alternatively, of one of the components
to be coated (as an assessment of the penetration rate of the
component into the porous substrate after coating), is placed on a
surface of the porous substrate and the time required for the
droplet to penetrate into the substrate pores is determined with a
timer or stopwatch.
[0061] In certain embodiments, the uncoated fibrous cement
substrate exhibits a water droplet penetration time of from about
0.1 to about 5 seconds, more preferably from about 1 to about 2
seconds, when tested according to the water droplet penetration
test method described above. In other embodiments, the coated
fibrous cement substrate exhibits a water droplet penetration time
of from about 2 seconds to about 15 seconds, more preferably from
about 5 seconds to about ten seconds, when tested according to the
water droplet penetration test method described above after
application and curing of a multi-component composition according
to the present invention. Preferably, a first-coated component of
the multi-component composition exhibits a penetration time of
about 0.5 to about 5 seconds when tested according to the component
droplet penetration test method described above. Preferably, a
second-coated component of the multi-component composition exhibits
a penetration time of about 5 to about 15 seconds when tested
according to the component droplet penetration test method
described above.
[0062] In further exemplary embodiments, the method includes the
step of removing at least a portion of the multi-component coating
composition from a surface of the substrate. In some embodiments,
removing at least a portion of the multi-component coating
composition from a surface of the substrate takes place after at
least some of the components penetrate into the substrate. In other
embodiments, the method includes the step of applying at least a
portion of the multi-component coating composition removed from the
surface of the substrate to a second fibrous cement substrate
surface, for example, a second fibrous cement substrate sheet or a
different portion of the surface of the first substrate sheet.
[0063] Removal of at least a portion of the multi-component
composition applied to the substrate surface may be achieved using
a number of methods. For example, the applied component may simply
be permitted to wick or penetrate into the porous substrate by
allowing sufficient time to elapse before applying a second
component as described above. Alternatively, at least a portion of
the multi-component coating composition may be removed from the
surface of the substrate by directing a gas stream against at least
a portion of the coated surface to blow off at least a portion of
the multi-component composition. Preferably, an air knife is used
to direct an air stream, which may optionally be heated, against
the substrate surface to remove at least a portion of the
multi-component coating composition. In certain preferred
embodiments, at least a portion of the removed portion of the
multi-component composition is recovered, recycled and applied to a
second substrate surface.
[0064] In additional embodiments, the method includes the step of
mixing at least a portion of the multi-component coating
composition removed from the surface of the substrate with at least
a portion of the multi-component coating composition not previously
applied to the substrate to form a recycled coating mixture before
applying the recycled coating mixture to a surface of a second
substrate.
[0065] Since, as noted above, fiber cement substrates typically
have a layered construction, to provide a uniform finish and at
least partially seal the substrates against water intrusion and
other environmental damage, each component is preferably applied to
at least the first major surface and at least one of the edges of
the substrate sheet. In other exemplary embodiments, each component
is also applied to the second major surface and each of the edges.
The applied film thickness may be varied by controlling the
rheology of the coating fluid, for example by controlling the
component's % NVM, or by controlling the application rate.
[0066] In some additional embodiments, the multi-component coating
composition may be applied to the fibrous cement substrate to
obtain an overall dry coating weight for the multi-component
coating composition of from about 0.5 g/m.sup.2 to about 75
g/m.sup.2(more preferably from about 1 to 40 g/m.sup.2, and most
preferably from 5 to 25 g/m.sup.2), and an overall dry film
thickness of from about 0.05 to about 3 mil (from about 1.25 to
about 75 microns), more preferably from about 0.1 to about 1 mil
(from about 2.5 to about 25 microns). Preferably, a first-applied
component is applied to the porous substrate to obtain a dry
coating weight of from about 1 g/m.sup.2 to about 20 g/m.sup.2, and
a second-applied component is applied to the porous substrate to
obtain a dry coating weight of from about 1 g/m.sup.2 to about 20
g/m.sup.2.
[0067] The invention will now be described with respect to certain
exemplary embodiments illustrated by the Figures and the Examples.
It should be understood that by specifying an order in the present
disclosure (e.g. an order of steps to be performed, an order of
layers on a substrate, etc.), it is not meant to preclude
intermediates between the items specified, as long as the items
appear in the order as specified.
[0068] Turning now to the figures, FIG. 1 illustrates a
multi-component coating method 100 according to an embodiment of
the present invention. In this illustrative embodiment, a first
component 104 is first applied to a substrate 114 at a first
application station, and subsequently a second component 124 is
applied to the coated substrate 114' at a second application
station in an in-line sequential coating process.
[0069] FIG. 1 shows a first storage container, typically a tank
102, containing a first component 104 of a multi-component
composition. For example, the first component may be an
amino-functional chemical compound. A supply fluid stream 106 of
the first component 104 is fed from the first storage tank 102 to
an applicator 110.
[0070] The applicator 110 may be any suitable coating device as
described above; however, a flood coater is shown for illustrative
purposes. The applicator 110 applies the first component 104 to a
substrate 114, which is shown for illustrative purposes as a
fibrous cement substrate sheet moving along a conveyor system
comprising a plurality of rollers 150. The applied coating stream
108 forms a flood coat 112 on at least one surface of the substrate
114. The surface may include one or more major surfaces such as a
face of the sheet, and one or more edge surfaces as shown in FIG.
1.
[0071] Optionally, as shown in FIG. 1, at least a portion 120 of
the applied coating stream 128 of the first component is removed
from a surface of the substrate 114. FIG. 1 illustrates use of an
air knife 116 that directs air, which may be heated, against the
surface of the substrate 114 after passage of a first component
penetration time; however, any suitable method may be used to
remove a portion of the coating from a surface of the substrate
114, including penetration of the coating into the pores of the
substrate 114. For illustrative purposes only, the first component
penetration time is determined as the time required for a point on
the substrate to move from the applicator 110 to the air knife 116,
and may be controlled by controlling the linear velocity of the
substrate 114 along the plurality of rollers 124 making up the
conveyor system in the direction shown by the arrow A.
[0072] A portion 120 of the applied first composition removed from
the surface of the substrate 114 may be collected in a pan 118. At
least some of the portion 120 of the applied first composition
removed from the surface of the substrate 114 and collected in pan
118 may be recycled in a recycle fluid stream 121, which optionally
mixes with the supply fluid stream 106 of the first component 104,
to form the applied coating stream 108 to the applicator 110.
Alternatively, at least some of the portion 120 of the applied
first composition removed from the surface of the substrate 114 and
collected in pan 118 may be recycled in a recycle fluid stream 121,
which optionally alternates with the supply fluid stream 106 of the
first component 104, to form the applied coating stream 108 to the
applicator 110.
[0073] Subsequently, the substrate (bearing the first component)
114' passes to a second application station where a second storage
container, typically a tank 122, contains a second component 124 of
a multi-component composition. For example, the second component
may be an oxirane-functional chemical compound. A supply fluid
stream 126 of the second component 124 is fed from the second
storage tank 122 to a second applicator 130.
[0074] The second applicator 130 may be any suitable coating device
as described above; however, a flood coater is shown for
illustrative purposes. The applicator 130 applies the second
component 124 to the substrate (bearing the first component) 114'.
The applied coating stream 128 forms a flood coat 132 on at least
one surface of the substrate 114'. The surface may include one or
more major surfaces such as a face of the sheet, and one or more
edge surfaces as shown in FIG. 1.
[0075] Optionally, as shown in FIG. 1, at least a portion 140 of
the applied coating stream 128 of the second component is removed
from a surface of the substrate 114'. FIG. 1 illustrates use of an
air knife 136 that impinges air, which may be heated, against the
surface of the substrate 114' after passage of a second component
penetration time to remove a portion of the applied mixed feed
stream 108. However, any suitable method may be used to remove a
portion of the coating from a surface of the substrate 114',
including penetration of the coating into the pores of the
substrate 114'. For illustrative purposes only, the second
component penetration time is determined as the time required for a
point on the substrate to move from the second applicator 130 to
the second air knife 136, and may be controlled by controlling the
linear velocity of the substrate 114' along the plurality of
rollers 124 making up the conveyor system in the direction shown by
the arrow A.
[0076] A portion 140 of the applied first composition removed from
the surface of the substrate 114' may be collected in a pan 138. At
least some of the portion 140 of the applied first composition
removed from the surface of the substrate 114' and collected in pan
138 may be recycled in a recycle fluid stream 142, which optionally
mixes and/or alternates with the supply fluid stream 126 of the
second component 124 to form the feed stream 128 to the second
applicator 130.
[0077] FIG. 2 illustrates a multi-component coating method 200
according to another embodiment of the present invention using two
mixers 207 and 211. In this illustrative embodiment, a first
component 204 is mixed with a second component 224 before
application to a substrate 214 at a single application station.
[0078] FIG. 2 shows a first storage container, typically a tank
202, containing a first component 204 of a multi-component
composition. For example, the first component may be an
amino-functional chemical compound. A supply fluid stream 206 of
the first component 204 is fed from the first storage tank 202 to a
first mixer 207. For illustration purposes only, a static in-line
mixer 207 is shown in FIG. 2, although other types of mixers may be
used. FIG. 2 also shows a second storage container, such as a tank
222, containing a second component 224 of a multi-component
composition. For example, the second component may be an
oxirane-functional chemical compound. A supply fluid stream 226 of
the second component 224 is fed from the second storage tank 222 to
the mixer 207.
[0079] A first mixed feed stream 209 including the first component
204 and the second component 224 is fed from the first mixer 207 to
a second mixer 211, and the second mixed feed stream 208 is fed to
an applicator 210. The applicator 210 may be any suitable coating
device as described above; however, a flood coater is shown for
illustrative purposes. The applicator 210 applies the second mixed
feed stream 208 containing the first component 204 and the second
component 224 to a substrate 214, which is shown for illustration
purposes as a fibrous cement substrate sheet moving in the
direction of arrow A along a conveyor system comprising a plurality
of rollers 250. The applied second mixed feed stream 208 forms a
flood coat 212 on at least one surface of the substrate 214. The
surface may include one or more major surfaces such as a face of
the sheet, and one or more edge surfaces as shown in FIG. 2.
[0080] Optionally, as shown in FIG. 2, at least a portion 220 of
the applied second mixed feed stream 208 is removed from a surface
of the substrate 214. FIG. 2 illustrates use of an air knife 216
that impinges air, which may be heated, against the surface of the
substrate 214 after passage of at least one component penetration
time to remove a portion of the applied mixed feed stream 208.
However, any suitable method may be used to remove a portion of the
coating from a surface of the substrate 214, including penetration
of the coating into the pores of the substrate 214. For
illustrative purposes only, the component penetration time is
determined as the time required for a point on the substrate to
move from the applicator 210 to the air knife 216, and may be
controlled by controlling the linear velocity of the substrate 214
along the rollers 250.
[0081] A portion 220 of the applied second mixed feed stream 208
removed from the surface of the substrate 214 may be collected in a
pan 218. At least some of the portion 220 of the applied second
mixed feed stream 208 removed from the surface of the substrate 214
and collected in pan 218 may be recycled in a recycle fluid stream
222, which mixes with the first mixed feed stream 209, including
the first component 204 and the second component 224, before
entering the second mixer 211 and forming the second mixed feed
stream 208 fed to the applicator 210.
[0082] FIG. 3 illustrates a multi-component coating method 300
according to an additional embodiment of the present invention
using a single mixer 307. In this illustrative embodiment, a first
component 304 is mixed with a second component 324 before
application to a substrate 314 at a single application station.
[0083] FIG. 3 shows a first storage container, typically a tank
302, containing a first component 304 of a multi-component
composition. For example, the first component may be an
oxirane-functional chemical compound. A supply fluid stream 306 of
the first component 304 is fed from the first storage tank 302 to a
mixer 307. For illustration purposes only, a static in-line mixer
307 is shown in FIG. 3, although other types of mixers may be used.
FIG. 3 also shows a second storage container such as a tank 322
containing a second component 324 of a multi-component composition.
For example, the second component may be an amino-functional
chemical compound. A supply fluid stream 326 of the second
component 324 is fed from the second storage tank 322 to the mixer
307.
[0084] A mixed feed stream 308 including the first component 304
and the second component 324 is fed from the mixer 307, and the
mixed feed stream 308 is fed to an applicator 310. The applicator
310 may be any suitable coating device as described above; however,
a flood coater is shown for illustrative purposes. The applicator
310 applies the mixed feed stream 308 containing the first
component 304 and the second component 324 to a substrate 314,
which is shown for illustration purposes as a fibrous cement
substrate sheet moving in the direction of arrow A along a conveyor
system including a plurality of rollers 350. The applied mixed feed
stream 308 forms a flood coat 312 on at least one surface of the
substrate 314. The surface may include one or more major surfaces
such as a face of the sheet, and one or more edge surfaces as shown
in FIG. 3.
[0085] Optionally, as shown in FIG. 3, at least a portion 320 of
the applied mixed feed stream 308 is removed from a surface of the
substrate 314. FIG. 3 illustrates use of an air knife 316 that
impinges air, which may be heated, against the surface of the
substrate 314 to remove a portion of the applied mixed feed stream
308 after passage of at least one component penetration time.
However, any suitable method may be used to remove a portion of the
coating from a surface of the substrate 314, including penetration
of the coating into the pores of the substrate 314. For
illustrative purposes only, the component penetration time is
determined as the time required for a point on the substrate to
move from the applicator 310 to the air knife 316, and may be
controlled by controlling the linear velocity of the substrate 314
along the plurality of rollers 350.
[0086] A portion 320 of the applied mixed feed stream 308 removed
from the surface of the substrate 314 may be collected in a pan
318. At least some of the portion 320 of the applied mixed feed
stream 308 removed from the surface of the substrate 314 and
collected in pan 318 may be recycled in a recycle fluid stream 322,
which joins with the mixed feed stream 308, including the first
component 304 and the second component 324, in the applicator
310.
[0087] FIG. 4 illustrates a multi-component coating method 400
according to an additional embodiment of the invention using a
single mixer 407. In this illustrative embodiment, a first
component 404 is mixed with a second component 424 before
application to a substrate 414 at a single application station.
[0088] FIG. 4 shows a first storage container, typically a tank
402, containing a first component 404 of a multi-component
composition. For example, the first component may be an
oxirane-functional chemical compound. A supply fluid stream 406 of
the first component 404 is fed from the first storage tank 402 to a
mixer 407. For illustration purposes only, a static in-line mixer
407 is shown in FIG. 4, although other types of mixers may be used.
FIG. 4 also shows a second storage container, typically a tank 422,
containing a second component 424 of a multi-component composition.
For example, the second component may be an amino-functional
chemical compound. A supply fluid stream 426 of the second
component 424 is fed from the second storage tank 422 to the mixer
407.
[0089] A mixed feed stream 409 including the first component 404
and the second component 424 is fed from the mixer 407, and the
mixed feed stream 409 is fed to a collection pan 418. In some
embodiments, the mixed feed stream 409 containing the first
component 404 and the second component 424 may further mix with any
material in the collection pan 418 that was previously removed from
a substrate 414 to form a multi-component coating mixture 420.
[0090] A recycle stream 421 from the collection pan 418 is fed to
an applicator 410. The recycle stream 421 contains the first
component 404 and the second component 424, and any material in the
collection pan 418 that was previously removed from a substrate
414. The applicator 410 may be any suitable coating device as
described above; however, a flood coater is shown for illustrative
purposes.
[0091] The applicator 410 applies the recycle stream 421 to a
substrate 414, which is shown for illustration purposes as a
fibrous cement substrate sheet moving along a conveyor system
comprising a plurality of rollers 424. The applied recycle stream
421 forms a flood coat 412 on at least one surface of the substrate
414. The surface may include one or more major surfaces such as a
face of the sheet, and one or more edge surfaces as shown in FIG.
4.
[0092] As shown in FIG. 4, collection pan 418 may collect material
removed from a surface of the substrate 414. FIG. 4 illustrates use
of an air knife 416 that directs air, which may be heated, against
the surface of the substrate 414 to remove a portion of the applied
recycle stream 421 after passage of at least one component
penetration time. However, any suitable method may be used to
remove a portion of the coating from a surface of the substrate
414, including penetration of the coating into the pores of the
substrate 414. For illustrative purposes only, the component
penetration time is determined as the time required for a point on
the substrate to move from the applicator 410 to the air knife 416,
and may be controlled by controlling the linear velocity of the
substrate 414 along the plurality of rollers 450 making up the
conveyor system in the direction shown by the arrow A.
[0093] FIG. 5 illustrates a multi-component coating method 500
according to a further embodiment of the present invention. In this
illustrative embodiment, a first component 504 is mixed with a
second component 524 before application to a substrate 514 at a
single application station.
[0094] FIG. 5 shows a first storage container, typically a tank
502, containing a first component 504 of a multi-component
composition. For example, the first component may be an
amino-functional chemical compound. A supply fluid stream 506 of
the first component 504 is fed from the first storage tank 502 to a
collection pan 518. The collection pan 518 may optionally include a
mixer, which is not shown in FIG. 5. FIG. 5 also shows a second
storage container, typically a tank 522, containing a second
component 524 of a multi-component composition. For example, the
second component may be an oxirane-functional chemical compound. A
supply fluid stream 526 of the second component 524 is fed from the
second storage tank 524 to the collection pan 518. In some
embodiments, the first component 504 and second component 524 may
mix within the collection pan 518 to form a multi-component coating
mixture 520.
[0095] A recycle stream 521 from the collection pan 518 is fed to
an applicator 510. The recycle stream 521 contains the first
component 504 and the second component 524, and any material in the
collection pan 518 that was previously removed from a substrate
514. The applicator 510 may be any suitable coating device as
described above; however, a flood coater is shown for illustrative
purposes.
[0096] As shown in FIG. 5, collection pan 518 may collect material
removed from a surface of the substrate 514. FIG. 5 illustrates use
of an air knife 516 that directs air, which may be heated, against
the surface of the substrate 514 to remove a portion of the applied
recycle stream 521 after passage of at least one component
penetration time. However, any suitable method may be used to
remove a portion of the coating from a surface of the substrate
514, including penetration of the coating into the pores of the
substrate 514. For illustrative purposes only, the component
penetration time is determined as the time required for a point on
the substrate to move from the applicator 510 to the air knife 516,
and may be controlled by controlling the linear velocity of the
substrate 514 along the plurality of rollers 550 making up the
conveyor system in the direction shown by the arrow A.
[0097] In each of the preceding embodiments, a first component and
a second component of a multi-component composition for coating a
porous substrate are mixed subsequent to leaving separate storage
tanks. Mixing may occur prior to application of the multi-component
composition to the porous substrate, after application to the
porous substrate, or both before and after application to the
porous substrate. In the preceding illustrative embodiments, the
first and second components are illustrated as an amino-functional
chemical compound and an oxirane-functional chemical compound that
undergo a chemical reaction (epoxidation) upon mixing. Other
embodiments are illustrated by the following examples.
EXAMPLES
[0098] In the following illustrative examples, various
multi-component compositions are prepared and applied to at least
one major surface of a porous substrate. The porous substrate in
each case was a fibrous cement substrate sheet having two major
surfaces adjoining a multiplicity of edge surfaces, each major
surface defining a plane having dimensions of 15.9 cm by 20.3 cm
and a surface area of 322.8 square centimeters. In each example, a
first component and a second component, capable of undergoing a
chemical reaction, were sequentially applied to the porous
substrate. The first and second components undergo a curing or
cross-linking reaction upon mixing. In each example, an optional
third coating composition was also applied to the porous substrate
as a topcoat.
[0099] In the examples, various amino-functional chemical compounds
were used as a first component or a second component, in
combination with various oxirane-functional chemical compound used
as a corresponding second or first component. For purposes of
illustration only, the following amino-functional chemical
compounds were used: those available under the trade designations
Anquamine 287, Anquamine 360, and Anquamine 701 from Air Products
Corp., Allentown, Pa.; and those available under the trade
designation EpiLink 360 from Air Products Corp., Allentown, Pa. For
purposes of illustration only, the following oxirane-functional
chemical compounds were used: those available under the trade
designation EpiRez 3515W60 and EpiRez 3522W60 from Resolution
Polymers, Inc., Houston, Tex.). In addition, in the examples and
for illustration purposes only, a topcoat available from The
Valspar Corp., Ashland, Ill. under the trade designation ColorPlus
LLW0106 topcoat was applied over the first component and second
component on the substrate.
[0100] In each of the examples, the first component and the second
component were dispersed or dissolved in a carrier liquid, tap
water, to achieve a desired percent non-volatile material (% NVM).
Percent NVM (% NVM) refers to the percentage of non-volatile
material in a coating component, and is generally expressed as a
weight percentage.
[0101] In each of the examples, a coater available under the trade
designation SeaWay Coater from SeaWay, Inc., Snohomish, Wash., was
used to apply the first component and the second component, and the
topcoat was then applied by curtain coater to a major surface (e.g.
a top surface) and the edges of the fibrous concrete substrate
boards. A "flood and blow" method was used to apply the first
component and the second component, in which a component was
applied to one or more surfaces of the substrate as a flood coat, a
penetration time period was allowed to elapse, and an air knife
impinged air against the coated surfaces, thereby "blowing off" a
portion of the applied coating from the coated surfaces.
[0102] In addition to the application rate determined by the flow
rate of the coating component through the applicator, the coating
weight applied to the substrate may be controlled by adjusting the
distance of the air knife from the substrate and the velocity and
temperature of the air impinging upon the substrate, with shorter
distance and higher velocity generally producing lower coating
weights. Coating weight refers to the weight of a component,
expressed on a dry solid weight basis, applied to a surface,
expressed as a surface area, and is generally reported in grams per
square meter (g/m.sup.2).
[0103] The penetration time period may be determined from the
Theological properties of the applied component, the surface
tension of the applied component, the porosity and relative
hydrophilicity of the substrate, the application temperature and
the humidity and moisture content of the substrate. Lower
viscosity, lower % NVM and lower surface tension generally favor
more rapid penetration and shorter penetration times, whereas
higher substrate porosity and hydrophilicity, higher application
temperature and higher humidity generally favor more rapid
penetration and shorter penetration times. In particular, too high
a % NVM value for the first-applied component may be undesirable
for sequentially applied coating components, because the
first-applied component may act to seal the porous surface and
prevent penetration of the second-applied component into the
substrate, possibly resulting in poor reaction of the components
and low adhesion to the substrate.
[0104] In the illustrative examples, Theological properties were
determined at low shear rate corresponding to coating leveling and
penetration into the porous substrate for some of the components of
the multi-component compositions. Viscosities were measured at
approximately 22-23.degree. C. using a Brookfield DV-II viscometer
(available from Brookfield Engineering Laboratories, Inc.,
Middleboro, Mass.) equipped with a number two spindle and operating
at 100 rpm. Measured Brookfield viscosities generally were from
about 1 to about centipoises (cP), more preferably from about 5 to
about 100 cP, most preferably from about 10 to about 30 cP.
[0105] In the illustrative examples, the fibrous concrete boards
were heated before and/or after application of each component, and
the board surface temperatures (BST) were recorded. BST refers to
the board surface temperature, that is, the temperature of the
substrate surface, expressed in degrees Celsius.
[0106] After application of the multi-component coating
compositions to the fibrous cement substrates and curing of the
composition, the coated substrates were tested for adhesion of the
applied coating and water permeability. Adhesion of the coating to
the porous substrate was determined at least 24 hours after coating
generally according to ASTM Test Method D 3359-97, by applying a
strip of adhesive tape (250 HB tape available from 3M Company, St.
Paul, Minn.) to the substrate's major coated surface using a roller
or other device to ensure good contact between the tape and the
substrate, then rapidly pulling an end of the tape strip to remove
the tape from the surface without first cutting an "X-pattern" into
the surface of the tape.
[0107] The adhesive side of the tape was then examined for evidence
that a portion of the fibrous substrate and/or the applied topcoat
had been removed with the tape, thereby adhering and partially
occluding the tape surface. Ratings of A-E were assigned to this
Dry Adhesion test result based on the visually-observed extent of
substrate and/or topcoat removal by the tape according to the
following scale: A: 0% removed; B: 1-10% removed; C: 11-25%
removed; D: 26-50% removed; and E (>50% removed). Additionally,
a plus (+) or (-) was assigned within a rating to indicate the
closest adjacent rating (e.g. an A- rating is closer to a B+ rating
than to an A rating; a B+ rating is closer to an A- rating than to
a B rating, and the like). An A rating is preferred over a B
rating, which is preferred over a C rating, and so on.
[0108] In addition, a Wet Soak test was carried out on the coated
substrates at least 24 hours after coating in order to assess the
water permeability of the applied multi-component coating
composition. In the Wet Soak test, the substrate was submerged in
water for 24 hours, then removed and dried. The Dry Adhesion test
according to the above method was then carried out on the sample,
and a rating assigned as above.
[0109] Preferably, the Dry Adhesion rating after the Wet Soak is
unchanged from the original Dry Adhesion rating, with the extent of
difference between the two ratings providing a relative measure of
the extent of water penetration into the sample, thereby damaging
or causing deterioration of the fibrous cement substrate surface.
The results are summarized in Table I.
TABLE-US-00001 TABLE I First Applied Second Applied Component
Component Third Applied Component Dry Wet Component Coating
Compontent Coating Component Coating Adhesion Soak Example &
NVM Weight & NVM Weight BST & NVM Weight BST A-E A-E Number
(% w/w) (g) BST (.degree. C.) (% w/w) (g) (.degree. C.) (% w/w) (g)
(.degree. C.) Scale Scale 1 EpiLink 4.12 87.8 3515W60 2.17 107.2
LLW0106 Topcoat 4.27 82.8 A C 360 12.5% in 10% in 5.6% in tap water
tap water tap water 2 3515W60 2.60 87.8 EpiLink360 4.64 107.2
LLW0106 Topcoat 4.12 80.0 A B 12.5% in 5.6% in 10% in tap water tap
water tap water 3 EpiRez 2.00 110.0 Anquamine 287 2.01 111.1
LLW0106 Topcoat 3.89 80.0 -- -- 3525W60 12.5% in 10% in 12.5% in
tap water tap water tap water 4 EpiRez 3525W60 3.16 109.4 Anquamine
287 2.78 111.7 LLW0106 Topcoat 4.27 76.7 -- -- 12.5% in 12.5% in
10% in tap water tap water tap water 5 Anquamine 287 2.18 106.1
EpiRez 3525W60 2.30 110.6 LLW0106 Topcoat 4.04 79.4 -- -- 12.5% in
12.5% in 10% in tap water tap water tap water 6 Anquamine 287 3.18
110.6 EpiRez 3525W60 3.80 108.3 LLW0106 Topcoat 4.30 79.4 -- --
12.5% in 12.5% in 10% in tap water tap water tap water 7 50/50 3.40
79.4 EpiRez 3515W60 2.60 107.2 LLW0106 Topcoat 2.80 -- A --
Anquamine 15% in 10% in 701/Anquamine 360 tap water tap water 15%
in tap water 8 50/50 3.00 82.2 EpiRez 3515W60 3.60 115.6 LLW0106
Topcoat 4.30 -- A -- Anquamine 15% in 10% in 701/Anquamine 360 tap
water tap water 15% in tap water 9 EpiRez 3515W60 3.20 93.3 50/50
3.20 90.6 LLW0106 Topcoat 3.30 -- B -- 15% in Anquamine 10% in tap
water 701/Anquamine tap water 360 15% in tap water 10 EpiRez
3515W60 3.00 99.4 50/50 3.30 82.2 LLW0106 Topcoat 3.60 -- A -- 15%
in Anquamine 10% in tap water 701/Anquamine tap water 360 15% in
tap water 11 EpiRez 3515W60 2.80 83.3 50/50 2.60 77.2 LLW0106
Topcoat 3.75 -- A -- 15% in Anquamine 10% in tap water
701/Anquamine tap water 360 15% in tap water 12 50/50 2.47 65.6
EpiRez 3515W60 2.70 65.6 LLW0106 Topcoat 3.75 -- A B Anquamine 15%
in 10% in 701/Anquamine 360 tap water tap water 15% in tap water 13
50/50 2.56 76.7 EpiRez 3515W60 2.45 60.0 LLW0106 Topcoat 3.35 -- A
B+ Anquamine 15% in 10% in 701/Anquamine 360 tap water tap water
15% in tap water 14 EpiRez 3515W60 3.20 72.2 50/50 2.60 67.2
LLW0106 Topcoat 3.02 -- A B 15% in Anquamine 10% in tap water
701/Anquamine tap water 360 15% in tap water 15 EpiRez 3515W60 2.90
60.0 50/50 2.60 65.6 LLW0106 Topcoat 3.29 -- A- B 15% in Anquamine
10% in tap water 701/Anquamine tap water 360 15% in tap water 16
75/25 0.40* 46.7 EpiRez 3051W60 0.45* 47.2 N/A N/A N/A A A
Anquamine 15% in 701/Anquamine 360 tap water 10% in tap water 17
75/25 0.45* 46.7 EpiRez 3515W60 0.45* 47.2 N/A N/A N/A A A
Anquamine 15% in 701/Anquamine 360 tap water 15% in tap water
*Expressed as dry film thickness in mils; N/A denotes not
applied
[0110] All patents, patent applications, and literature cited in
the specification are hereby incorporated by reference in their
entirety. In the case of any inconsistencies, the present
disclosure, including any definitions therein will prevail. The
invention has been described with reference to various specific and
preferred embodiments and techniques. However, it should be
understood that many variations and modifications may be made while
remaining within the spirit and scope of the invention. The
foregoing detailed description of the present invention is not
intended to describe every embodiment or every implementation of
the present invention.
[0111] Various embodiments of the invention have been described.
These and other embodiments are within the scope of the following
claims.
* * * * *