U.S. patent application number 10/033626 was filed with the patent office on 2003-07-03 for stain resistant acoustical panels.
Invention is credited to Belmares, Hector, Caldwell, Kenneth G., Vazquez, Alejandrino.
Application Number | 20030124330 10/033626 |
Document ID | / |
Family ID | 21871477 |
Filed Date | 2003-07-03 |
United States Patent
Application |
20030124330 |
Kind Code |
A1 |
Belmares, Hector ; et
al. |
July 3, 2003 |
Stain resistant acoustical panels
Abstract
Disclosed is a stain resistant acoustical panel. The panel may
incorporate within its structure a relatively small quantity of
latex which forms an ultra thin coating within the panel such that
water may pass through the inner structure of the panel.
Furthermore, the panel may have a coating or primer applied to the
facing side of the panel to prevent water stains. The coating
contains a chelating agent which provides stain resistance to the
coated face of the panel. Additionally, the panel may incorporate
both latex within its structure and a primer coating comprising a
chelating agent.
Inventors: |
Belmares, Hector;
(Lancaster, PA) ; Vazquez, Alejandrino;
(Lancaster, PA) ; Caldwell, Kenneth G.;
(Mountville, PA) |
Correspondence
Address: |
Womble Carlyle Sandridge & Rice, PLLC
P.O. Box 7037
Atlanta
GA
30357-0037
US
|
Family ID: |
21871477 |
Appl. No.: |
10/033626 |
Filed: |
December 27, 2001 |
Current U.S.
Class: |
428/295.1 |
Current CPC
Class: |
C09D 5/1693 20130101;
Y10T 428/249986 20150401; C08K 3/22 20130101; E04B 1/86 20130101;
Y10T 428/249924 20150401; C09D 7/61 20180101; Y10T 428/249953
20150401; Y10T 428/249933 20150401; E04B 2001/8461 20130101; Y10T
428/2913 20150115 |
Class at
Publication: |
428/295.1 |
International
Class: |
B32B 025/02 |
Claims
1. A stain resistant acoustical panel comprising: a first major
surface and an opposing second major surface; and at least one of
the major surfaces having a coating including a chelating
agent.
2. The stain resistant acoustical panel of claim 1, wherein the
coating further comprises a binder and a filler.
3. The stain resistant acoustical panel of claim 2, wherein the
coating comprises on a dry weight percent basis of between about
1.5% to about 35% binder.
4. The stain resistant acoustical panel of claim 2, wherein the
binder is hydrophilic.
5. The stain resistant acoustical panel of claim 4, wherein the
binder is selected from the group consisting of starch, polyamides,
polyacrylamides, polymethacrylamides, proteins, polyvinyl alcohol,
latex, polyureas and mixtures thereof.
6. The stain resistant acoustical panel of claim 2, wherein the
coating comprises on a dry weight percent basis of between about
35% to about 99% filler.
7. The stain resistant acoustical panel of claim 2, wherein the
filler is selected from the group consisting of calcium carbonate,
talc, perlite, dolomite, sand, barium sulfate, mica, silica,
gypsum, wollastonite, calcite, aluminum trihydrate, zinc oxide,
zinc sulfate, solid polymer particles, hollow beads and mixtures
thereof.
8. The stain resistant acoustical panel of claim 1, wherein the
coating comprises on a dry weight percent basis of between about
0.1% to about 25% of chelating agents.
9. The stain resistant acoustical panel of claim 1, wherein the
chelating agent comprises a metal oxide.
10. The stain resistant acoustical panel of claim 9, wherein the
metal oxide is selected from the group consisting of zinc oxide,
aluminum oxide, zirconium oxide and combinations thereof.
11. The stain resistant acoustical panel of claim 1, wherein the
chelating agent is selected from the group consisting of soluble
zirconium, aluminum, zinc and combinations thereof.
12. A stain resistant acoustical panel comprising: fibers; starch;
and a latex wherein the ratio of latex to starch on dry weight
percent basis is between about 1 to 330 and about 1 to 4.1.
13. The stain resistant acoustical panel of claim 12, wherein the
latex further comprises a functional group selected from the group
consisting of carboxylic acid, methylol, hydroxyl, urethane, amide,
urea and combinations thereof.
14. The stain resistant acoustical panel of claim 13, wherein
carboxylic acid comprises from about 0.02% to about 7% by weight of
the latex.
15. The stain resistant acoustical panel of claim 12, wherein the
ratio of latex to starch on a dry weight percent basis is between
about 1 to 49 and about 1 to 4.5.
16. A stain resistant acoustical panel comprising: fibers; starch;
a latex wherein the ratio of latex to starch on dry weight percent
basis is between about 1 to 330 and about 1 to 4.1; and a coating
including a chelating agent applied to a facing side of the
panel.
17. The stain resistant acoustical panel of claim 16, wherein the
coating further comprises a binder and a filler.
18. The stain resistant acoustical panel of claim 16, wherein the
latex further comprises a functional group selected from the group
consisting of carboxylic acid, methylol, hydroxyl, urethane, amide,
urea and combinations thereof.
19. The stain resistant acoustical panel of claim 18, wherein
carboxylic acid comprises from about 0.02% to about 7% by weight of
the latex.
20. The stain resistant acoustical panel of claim 18, wherein the
ratio of latex to starch on a dry weight percent basis is between
about 1 to 49 and about 1 to 4.5.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to acoustical panels
and in particular it relates to stain resistant acoustical
tiles.
BACKGROUND
[0002] Acoustical panels are often prone to stains caused by water
soaking into the panel. This is especially true for ceiling panels
stained by water dripping from a leaky roof. Such water damage
leaves a permanent visible mark on the front face of the acoustical
panel which destroys the aesthetics of the overall ceiling panel
grid. Water stains occur most often when starch or starch mixtures
are used as internal binders within the panel. Staining is believed
to be the result of scorched starch, iron compounds and dyes from
recycled cellulosic fibers from newspapers ("newsprint") being
brought to the front face of the panel by water being absorbed by
the panel.
[0003] Acoustical panels typically comprise binders and fibers.
Starch is the most common binder used in the formation of
acoustical panels. The fibers added include mineral fiber (mineral
wool), glass fiber, texpanel fiber and natural fibers such as
cellulose from newsprint. Fibers contribute to the wet strength of
the board as it is converted from the aqueous slurry to the
substantially solid cake (wet formation) before forming the
finished panel. Newsprint contributes significantly to the staining
of the panel. Acoustical panels may also include clays, expanded
perlite, dolomite, calcium carbonate, calcium sulfate hemihydrate,
flocculants and surface active agents.
[0004] Additional binders include latexes which have been added to
improve panel sag resistance under high humidity since starch is
hydrophilic and its binding properties degrade in the presence of
high humidity. Typically, latex is added as part of the binder mix
comprising both starch and latex. The latex component commonly
comprises the majority of the binder mix. Latexes are hydrophobic
and are not susceptible to moisture.
[0005] Current efforts to prevent water damage to acoustical panels
are directed at preventing the water from entering the inner
structure of the panel. One of the most common methods is the
incorporation of latexes as a binder into the panel such that water
is blocked from entering the inner structure of the panel.
Additionally, an impermeable backing may be applied to the back
side of the panel to prevent water from being absorbed into the
panel. Unfortunately, such methods only redirect the water to the
outer edges of the panel which can cause a "picture frame effect"
to form on the facing of the panel. The "picture frame effect"
results in a visible water stain framing the outer edges of the
front face. This effect can be caused by water being absorbed at
the edges of the panel and by the rusting of the support grid of
the ceiling system.
SUMMARY
[0006] The present invention includes a stain resistant acoustical
panel. The panel may incorporate within its structure a relatively
small quantity of latex which forms an ultra thin coating within
the fibrous panel such that water may pass through the inner
structure of the panel. The panel also provides a mechanism for
leak detection since water is allowed to flow through the panel
where the leak can be detected long before a resulting stain is
visible in a conventional panel.
[0007] Furthermore, the panel may have a coating or primer applied
to the facing side of the panel for preventing water stains. The
coating contains a chelating agent which provides stain resistance
to the coated face of the panel. Additionally, the panel may
incorporate both latex within its structure and a primer coating
comprising a chelating agent to provide enhanced stain resistance
to the panel.
[0008] In an embodiment, the stain resistant acoustical panel
includes at least one side of the panel coated with a primer that
includes a chelating agent. The chelating agent may be a metal
oxide such as zinc oxide, aluminum oxide and zirconium oxide.
Additional examples of chelating agents include soluble zirconium,
aluminum and zinc compounds. The primer coating may further include
a binder and a filler. The binder can be a hydrophilic binder such
as a starch, polyamides, polyacrylamides, proteins, polyvinyl
alcohol, latex, polyureas and mixtures of the above. The binder may
comprise between about 1% to about 40% dry weight of the primer
coating. The filler may comprise between about 35% to about 99% by
dry weight of the primer coating and may be chosen from the group
of calcium carbonate, talc, perlite, dolomite, sand, barium
sulfate, mica, silica, gypsum, wollastonite, calcite, aluminum
trihydrate, zinc oxide, zinc sulfate, solid polymer particles,
hollow beads and mixtures of the above.
[0009] A further embodiment includes a stain resistant acoustical
panel comprising fibers, a starch and a latex wherein the ratio of
latex to binder on a dry weight percent basis is between about 1 to
330 and about 1 to 4.1. The latex may include a functional group
such as carboxylic acid, methylol, hydroxyl, urethane and an amide.
The carboxylic acid may comprise between about 0.02% to about 7% by
dry weight of the latex. The ratio of latex to binder on a dry
weight percent basis is between about 1 to 49 and about 1 to
4.5.
[0010] An additional embodiment includes a stain resistant
acoustical panel including fibers, a water soluble binder, and a
latex wherein the ratio of latex to binder on dry weight percent
basis is between about 1 to 330 and about 1 to 4.1. Furthermore,
the acoustical panel includes a coating having a chelating agent
applied to the facing side of the panel. The coating may include
both a binder and a filler.
DETAILED DESCRIPTION
[0011] The present invention comprises a stain resistant acoustical
panel wherein water may flow through the inner structure of the
panel such that water may enter the back side of the panel and then
exit the facing side of the panel. The panel may have incorporated
within its structure a quantity of latex which forms an ultra thin
coating within the fibrous panel. Furthermore, the panel may have a
coating or primer applied to at least one side of the panel.
Typically, the coating is applied to the facing side of the panel.
The coating contains a chelating agent which provides stain
resistance to the coated face of the panel. Additionally, the panel
may incorporate both latex within its structure and a primer
coating comprising a chelating agent to provide enhanced stain
resistance to the panel.
[0012] In an embodiment, a small amount of latex is added to
prevent staining by incident water on the panel. The amount of
latex added is described as being small given that latex is added
in amounts which impart stain resistance but is not added in
amounts which would impart any significant sag resistance to the
acoustical panel. The relatively small amount of latex typically is
added to the acoustical panel composition during the wet formation
process but may be added when the panel has been dried. Starch,
starch derivatives, or mixes thereof may be added to the acoustical
panel composition as the binder. For example starch may include
native starches, purified and non-purified starches, non-ionic
starches, and derivatives include anionic, cationic, lipophilic,
fat replacers, dextrins, carboxylated starch, ethoxylated starch,
starch esters, hydroxyethylated starch and mixtures thereof. Of
course there are other examples of starch which are fully
contemplated and understood as being able to be incorporated with
the present panel.
[0013] When added, the latex spreads forming an ultra thin coating
within the panel. Starch acts as a binder to keep the panel
composite coherently adhered. The latex comprises from about 0.3%
to less than about 20% of either anionically, cationically, or
no-charge stabilized resin latex on dry weight percent basis of the
starch and latex mix and the starch comprises from more than about
80% to 99.7% based on the dry weight of total latex and starch
solids, or from 80.1% to 95% and may comprise from 81% to 90%.
Based on the total dry weight solids of the panel, latex and starch
together may comprise from about 1.5% to 35%, or from about 1.5% to
20% and may comprise from about 2% to 18%.
[0014] The relatively small amount of thermoplastic latex seals the
staining agents by coating the fibers of the panel internally with
an ultra thin film of water-impermeable thermoplastic, thus
avoiding the leaching out of staining agents. Amounts of latex
greater than the above ranges may hinder the water transport
through the cross section of the panel and the water will start
running undesirably over the panel edges.
[0015] The resin latexes may be either anionically, cationically,
or no-charge stabilized. For example, anionically stabilized resin
emulsions typically have pH above 7. Some may contain a small
proportion of ionizable functional groups such as carboxyl groups
that may be at least partly neutralized to obtain negative charges
in the emulsified particle. Cationically stabilized resin emulsions
typically have quaternary ammonium moieties stable at all pH
values, or contain amine groups that in an acid medium give a
positively charged particle. No-charge stabilized resins typically
contain hydrophobic resin compositions with a given amount of
copolymerized polyvinyl alcohol moieties, the latter acting as the
hydrophilic counterpart to produce some degree of surfactant
character to the particle, thus the particle becomes stabilized in
a water emulsion.
[0016] In an embodiment, resin latexes with chemical functional
groups that favor adhesion to the panel components and starch
binder may be used. Examples of the chemical functional groups
include carboxylic acid, methylol (from formaldehyde), hydroxyl,
urethane, urea, and amide groups. For example, typical amounts of
carboxylic acid contents (as acrylic acid) are from about 0.02% to
7% by weight of dry latex. This range is equivalent to 0.16 to 54.6
acid number expressed as mg of KOH per gram of dry latex polymer.
Levels up to the point where the resin will be water soluble
typically occurs at about 15% to 30% carboxyl content (as acrylic
acid) depending on the resin latex. The latter range is equivalent
to 117 to 195 acid number. When the resin becomes water soluble it
flows through the panel and does not form an ultra thin impermeable
coating.
[0017] Higher acid numbers, crosslinking of the polymer by means of
covalent bonding or ionic bonding such as with zinc (II) and/or
zirconium (IV) compounds can be used to render the polymer
water-insoluble and therefore useful for this invention.
Furthermore, hydrophobic latexes based on acrylic/styrene chemistry
containing about 3% carboxyl acid functionality (as acrylic acid)
with an acid number of 23 are highly effective to prevent staining
of the panels caused by water transport through the panel.
[0018] The primer coating may be placed before applying the panel's
decorative front face. The primer coating contains chelating agents
in a coating composition to remove staining compounds that might
have passed through the panel, particularly when the water itself
is contaminated with staining compounds. Furthermore, the primer
coating works synergistically with the latex coating to further
reinforce the antistaining properties of the latex. The primer
coating composition basically includes a binder, filler, and the
chelating complexing agents that chelate the staining compounds
carried by the water. Other compounds can be added, such as, but
not limited to, surfactants, dispersant agents, pigments, buffer
agents, and viscosity controllers.
[0019] Different compatible fillers can be added. For example,
typical fillers can include calcium carbonate, talcs, platy talcs,
perlite, dolomite, sand, barium sulfate, mica, silica, gypsum,
wollastonite, calcite, aluminum trihydrate, zinc oxide, zinc
sulfate, solid polymer particles, hollow beads, and mixtures
thereof. The range of incorporation in the composition may be from
about 35% to about 99.4%, from 79% to 96% and from 88% to 94%
solids by weight of dry primer coating.
[0020] The binders for this invention are hydrophilic. The
hydrophilic binder, being water compatible and in some cases
slightly water-soluble allows the absorption of water and
water-soluble staining compounds within the whole extension of the
primer coating itself. This brings forth a wide distribution of
water into the body of the hydrophilic acoustical panel before it
reaches the panel front face as well as an effective removal of
staining compounds from the water by the primer coating, thus
avoiding localized flow of water into a relatively small portion of
the primer coating.
[0021] An example of hydrophilic binders includes starches and
starch-based compounds; polyamides such as polyacrylamides,
polymethacrylamides, proteins; polyvinyl alcohol compounds; latex
emulsions in water or polymers where the resin contains a large
proportion of carboxyl or similar hydrophilic groups; polyureas;
and the like. Preferred binders include starch and starch-based
compounds. The range of incorporation in the composition is from
0.5% to 40%, preferably from 3% to 9% and most preferably from 4%
to 7% solids by weight of dry primer coating.
[0022] Chelating agents are compounds that can perform strong
chemical complexation with staining compounds. Staining compounds
cause aesthetical damage to the panel decorative front face. The
chemical nature of these staining compounds is not known but it is
believed that organic and inorganic mixtures of compounds are
present in the stain, such as scorched starch, iron compounds, dyes
from the newspapers used as source of cellulosic fibers.
[0023] Example chelating agents include tannin stain inhibitors
available from (Halox Corporation, Hammond, Ind., USA). Such
formulations comprise soluble zirconium, aluminum, and zinc at a pH
above 7. These tannin stain inhibitors form insoluble chelated
tannins that stop the migration of soluble tannins towards the
decorative wood paint. Examples include XTAIN L-44 (30% solids in
water-based formulation), XTAIN A, BW-100, and CZ-170, each
available from Halox Corporation, Hammond, Ind., USA. Typical
binders for the above example chelating agents include hydrophobic
polymers such as polyvinyl acetate, vinyl acrylics, straight
acrylics, latex emulsions, and solvent based alkyds, where the
solvent based alkyds are the most effective to stop the migration
of tannins and the polyvinyl acetate the least effective.
[0024] Furthermore, the chelating agent may comprise soluble or
insoluble metal salts and oxides can also be used for the present
invention in place of the commercial proprietary formulations cited
above. Examples include zinc oxide, aluminum oxide
(chromatographic, ordinary, adsorbent grade, etc.), zirconium
oxide, and mixes thereof. Soluble salts of aluminum, zinc,
zirconium, and the like, mixes thereof, or in combination with
chelating metal oxides can also be used. The range of incorporation
in the composition is from about 0.1% to 25%, from about 1% to 12%
or from about 2% to 5% solids by weight of dry primer coating. The
final dispersion may be well shaken or stirred before use.
[0025] For the primer, the application rate range of dry solids is
from about 1 g/sq.ft. to about 180 g/sq.ft. of substrate
geographical surface, with preferred range from 5 g/sq.ft. to 30
g/sq.ft., and most preferred from 7 g/sq.ft. to 15 g/sq.ft. The
primer is applied on the acoustical panel surface before the
application of the final decorative panel face. Other intermediate
primers or paint coatings that fulfill specific purposes can also
be applied before or after the application of the chelating
primer.
[0026] Acoustical Panels
[0027] Acoustical panels comprise a large variety of materials with
varied applications. Acoustical panels may include glass fiber,
mineral fiber, gypsum, vinyl-coated-gypsum, mixtures thereof,
metal, ceramic materials, wood, plastic, and the like.
Additionally, the panels may include fillers, dispersing compounds,
flocculants, pigments, binders, and many other materials organic
and inorganic to introduce specific properties to the acoustical
panel. Applications for the acoustical panels include ceiling
panels, support grids for ceiling panels, walls, partition boards,
and panels. Paints for acoustical panels can have varied
compositions to impart the specific properties desired for the
panel. Paints may impart specific properties to the surface of the
panel such as porosity, smoothness, a rough and irregular surface.
The panel may be punched with holes, fissures and other patterns to
modify and improve acoustical properties.
[0028] Surface-Active Agents
[0029] Wetting of surfaces, particularly by the chelating primer
compositions can be an important factor for further enhancement of
the spreadability and adhesion of the chelating primer compositions
on the acoustical ceiling panels, thus enhancing the overall
performance of the coated surface. Also, the surface-active agent
favors the dispersion and stability of the suspended particles such
as fillers. Further wetting of other additives such as pigments is
also favored by the addition of the surface-active agent.
[0030] Other Additives
[0031] Compositions or compounds that fulfill specific tasks may be
added to the primer coating composition. Without limiting the
invention, examples of such compositions or compounds include
dispersants, defoamers, antioxidants, pigments, light-scattering
pigments, solvents, viscosity affecting agents, stabilizers,
biocides, and pH-controlling buffers that can be added to the
composition to enhance performance or processing.
[0032] Coating Process and Methods
[0033] The chelating primer composition can be applied to a surface
of acoustical panels by spraying, dip-coating, spin-coating, brush
painting, roll coating, knife coating, and curtain coating. The
composition can be applied to a large variety of acoustical panel
surfaces. After drying and/or thermally curing the chelating primer
coating, the composition typically forms an adherent coating.
[0034] One way to control coating thickness is by altering the
percent solids (by weight) of the chelating primer dispersion that
contains all the additives and surface-active agents. The percent
solids can be from 1% to 90%, preferably from 25% to 75% wt. %, and
most preferably from 40% to 60% of the dispersion. Another way to
control coating thickness is by altering the amount of dispersion
placed on the substrate surface. Water may be used as a suspending
liquid, however, other solvents may be used in combination with
water.
[0035] Once applied to the surface, the chelating primer coating is
permitted to dry and/or cure. This can be done at ambient
temperature, or may be heated in a convection oven or preferably in
a forced-air draft oven to assist or shorten the drying and/or
curing process. The range of temperatures is from ambient
temperature to 250.degree. C, preferably from 50.degree. to
225.degree. C. and most preferably from 60.degree. to 200.degree.
C. Optionally, an infrared oven, a heating gun, a microwave oven,
an infrared laser, or other sources of thermal energy can also be
used as the source of heat for coating drying and/or curing.
[0036] Applications
[0037] Acoustical panels include, without limiting the invention,
ceiling panels, walls, partition boards, panels, and the like.
Acoustical panel paints can have varied compositions to impart the
specific properties desired for the panel.
EXAMPLES
[0038] Testing Procedures
[0039] In the following examples, certain antistaining properties
of the latex-containing acoustical panels and/or applied chelating
primer discussed above were determined using the following
procedures.
[0040] Stain Resistance
[0041] This test is carried out to measure the stain resistance of
the acoustical panel. Staining is typically caused by water
dripping on the back face of the panel. Water permeates the panel
and goes through it dissolving staining materials contained in the
panel from the binder composition and other contaminants contained
within the panel such as newspaper printing inks. In addition, the
water itself may contain staining materials before going through
the panel.
[0042] In the experiment, from a 100 ml chemical biuret, 20 ml of
water are allowed to drip in one hour onto the back face of an
acoustical panel. The panel is horizontally positioned. Test panel
dimensions are 2 ft. by 2 ft. The tip of the biuret is about one
foot away from the test panel. The cycle is repeated every 24 hours
until staining appears on the decorative panel front face. Even a
minimal amount of visible stain is considered a failure and the
test is terminated. Time for appearance of staining is measured in
days and recorded. In addition, a stain rating is also recorded as
well as the time in days that it takes for the decorative panel
front face to appear visibly wet. The stain rating is as
follows:
1 No stain = 5 Slight stain = 4 Moderate stain = 3 Extensive stain
= 2 Very extensive stain = 1 Disastrous stain = 0
[0043] The test is run with panels having a white decorative front
face to make the test more astringent in the detection of incipient
stains.
Example 1
[0044] Commercial product acoustical panel Minaboard, generic
white, fine fissured with punched acoustical holes available from
Armstrong World Industries, Lancaster, Pa., USA was used in all
testing that follows described in every one of the Examples. The
panels were manufactured following the procedural teachings of U.S.
Pat. Nos. 4,963,603 and U.S. Patent No. 5,277,762. The starch
content was 2.1% by weight of dry panel solids. The latex emulsion
was Rhoplex EWP-466 available from Rohm and Haas Co., Philadelphia,
Pa., USA, a carboxylic acid/styrene/acrylic terpolymer with a low
content of carboxylic acid (acid number of 23 equivalent to 2.95%
of acrylic acid on dry basis). The dry weight of latex was 0.35% of
the total weight of dry panel solids. In Example 1 the dry latex
content is 14.3% of the latex-starch composition based on the dry
weight of total latex and starch solids. Rhoplex EWP-466 latex is
one of the most hydrophobic carboxylated acrylic thermoplastics
typically available commercially. The carboxyl groups act as an
anchor to attach to the relatively hydrophilic panel components.
The panels were dried, primer coatings applied and then
decoratively painted on the front face. The panel properties for
the latex-treated panel and a comparison of results with an
untreated control are shown in Table 1.
2TABLE 1 Comparison of latex-treated (Rhoplex EWP-466 latex) fine
fissure Minaboard acoustical ceiling panel vs. an untreated
control. Latex-treated Minaboard Control Minaboard Time for stain
appear- 49 days 1 day ance Stain rating at first ap- 4-5 1 pearance
Time for front-face to 45 days 10 minutes appear wet
[0045] Table 1 shows the high stain resistance conferred by the
introduction of a small amount of carboxylated styrene/acrylic
latex. Table 1 also shows that the water flow through is kept,
although at a diminished rate. This gives more time for the water
to diffuse throughout the panel as shown by a time of 45 days
before the water wets the front panel decorative face as compared
with only 10 minutes for the control. Neither for the control nor
for the test panel, water dripping on the back of the panel ran
over the panel edge.
Comparative Example 1
[0046] As in Example 1, except that the dry weight of latex Rhoplex
EWP-466 was 1% of dry panel solids. Here the dry latex content was
32.3% of the latex-starch composition based on the dry weight of
total latex and starch solids. For the staining test, the water
remained on the back surface of the panel and did not flow through
the panel, thus running laterally over the panel edges. The panel
was internally completely sealed to flow of water by the latex at
said concentration.
Example 2
[0047] The same as Example 1, except that Rhoplex EWP-466 latex was
substituted by Airflex 4530 latex (Air Products and Chemicals,
Inc., Allentown, Pa., USA). The Airflex 4530 latex dry weight was
at a concentration of 0.5% of dry panel solids. In this Example 2,
the dry latex content is, 19.2% of the latex-starch composition
based on the dry weight of total latex and starch solids. Airflex
4530 is a terpolymer of ethylene/vinylchloride/acrylamide with 2%
of acrylamide by weight of dry solids. Time for front-face to
appear wet was 20 minutes Time for stain appearance was 2 days, and
stain rating was 3.
[0048] Example 2 shows that amide groups in a hydrophobic polymer
are less effective than carboxylic groups (Example 1) to impart
antistain properties to the acoustical panel. This is believed to
be due to the lesser adhesive properties of amide functional groups
towards panel components thus causing a significantly decreased
tendency to form a protective film inside of the acoustical panel
when compared with carboxylated styrene/acrylic Rhoplex
EWP-466.
Example 3
[0049] a) Chelating Primer Coating
[0050] A chelating primer-coating composition was prepared by
adding to a reactor, with strong stirring, and in the order
mentioned, 3680 g of deionized water; 268 g. of Ethylex 2025 powder
(starch-based compound, water soluble) (A.E. Haley Mfg, Co.,
Daphne, Ala., USA); 499 g. of XTAIN L-44 (chelating agents, 30%
solids in water) (Halox Corporation, Hammond, Ind., USA); 5,460 g
of Hydrocarb 60 slurry (calcium carbonate 70% solids in water)
(OMYA, Inc., Proctor, Vt., USA); 27 g of Metasol D3T-A (liquid
biocide) (Calgon Corp., Harleysville, Pa., USA); 7. Og of Colloid
797 (liquid defoamer) (Rhone Poulenc, Marietta, Ga., USA); and 59 g
of Natrosol FPS-HB (liquid thickener, 25% solids) (Aqualon Co.,
Wilmington, Del., USA).
[0051] b) Primer-Coating Control Without Chelating Agents
[0052] Same as in (a) above but without XTAIN-L44.
[0053] c) Coating Procedure. Test Sample
[0054] An uncoated bare board commercial acoustical panel
Minaboard, fine fissured with punched acoustical holes (Armstrong
World Industries, Lancaster, Pa., USA) was spray coated on the
panel face with primer-coating composition described in (a)
containing chelating agents. The coating was dried and cured at
350.degree. F. for 10 minutes. The weight of the dry coating was 9
g/sq.ft. Then a second primer coating was applied with the
composition described in (b) (no chelating agents). The coating was
dried and cured at 350.degree. F. for 10 minutes. The weight of the
second primer coating was 1 g/sq.ft. on dry coating composition
basis. Finally, the standard commercial decorative face paint
generic white was applied to the panel and dried at 310.degree. F.
for 8 minutes.
[0055] d) Coating Procedure. Control Panel
[0056] A control panel identical to the one described in (c) above
was prepared. The procedure was identical except that none of the
two primer-coatings contained chelating composition. Both layers of
coating were identical, and each coating weighed 9 g/sq.ft on dry
basis. Results are shown in Table 2 for a comparison of a test
Minaboard panel chelating primer-coated and a control
chelating-untreated Minaboard panel.
3TABLE 2 Comparison of chelating primer-coated fine fissure
Minaboard acoustical ceiling panel vs. an untreated control.
Primer-coated Minaboard Control Minaboard Time for stain appear- 7
days 1 day ance Stain rating at first ap- 2 1 pearance Time for
front-face to 4 days 10 minutes appear wet
[0057] Table 2 shows that the chelating primer coating is an
effective agent to remove stains caused by staining agents within
the acoustical panel.
Example 4
[0058] To demonstrate the synergism between internally
latex-treated panel and chelating primer-coated panel, a Minaboard
panel described in Example 1 was treated following the procedure of
said Example 1 and afterwards a chelating primer-coating was placed
following Example 3. Table 3 shows the results of this test.
4TABLE 3 Comparison of latex-treated (Rhoplex EWP-466)-chelating
primer-coated fine fissure Minaboard acoustical ceiling panel vs.
an untreated control. Latex and chelating primer-coated Minaboard
panel Control Time for stain appear- larger than 56 days* 1 day
ance Stain rating at first ap- 5 (no stain) 1 pearance Time for
front-face to larger than 56 days* 10 minutes appear wet *Test
interrupted due to length of time. The synergistic effect between
the latex-treated panel and the chelating primer-coating on the
front face avoided any appearance of stain and prevented the
appearance of wetness on the decorative panel front face, even when
there was water flow through the panel. No water went over the
panel edges.
[0059] While Applicants have set forth embodiments as illustrated
and described above, it is recognized that variations may be made
with respect to disclosed embodiments. Therefore, while the
invention has been disclosed in various forms only, it will be
obvious to those skilled in the art that many additions, deletions
and modifications can be made without departing from the spirit and
scope of this invention, and no undue limits should be imposed
except as set forth in the following claims.
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