U.S. patent application number 15/688986 was filed with the patent office on 2018-03-08 for treatment composition containing a mold inhibiting agent and a water repellent having reduced foaming properties.
The applicant listed for this patent is Lonza Inc.. Invention is credited to Tyler Corse, Patrick Flaherty, Craig Waldron.
Application Number | 20180066400 15/688986 |
Document ID | / |
Family ID | 59923547 |
Filed Date | 2018-03-08 |
United States Patent
Application |
20180066400 |
Kind Code |
A1 |
Waldron; Craig ; et
al. |
March 8, 2018 |
Treatment Composition Containing A Mold Inhibiting Agent and A
Water Repellent Having Reduced Foaming Properties
Abstract
The present disclosure is generally directed to a mold
inhibiting composition. The mold inhibiting composition can be used
to treat various different substrates, including building material
products, such as facing layers for wallboard. In general, any
suitable paper product may be treated with the composition. The
composition contains a mold inhibiting agent in combination with a
defoamer. The mold inhibiting agent may comprise a pyrithione. The
defoamer, on the other hand, may comprise an oil based defoamer
containing metal oxide particles, such as silica particles. The
mold inhibiting composition can be combined with a water repellent
and applied to a substrate without excessive amounts of foam or
froth being formed. The defoamer is selected so as to not interfere
with the resulting water absorption properties of the product.
Inventors: |
Waldron; Craig; (Acworth,
GA) ; Flaherty; Patrick; (Cumming, GA) ;
Corse; Tyler; (Murrieta, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lonza Inc. |
Allendale |
NJ |
US |
|
|
Family ID: |
59923547 |
Appl. No.: |
15/688986 |
Filed: |
August 29, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62383045 |
Sep 2, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 2419/00 20130101;
B32B 2307/7145 20130101; C09D 5/1687 20130101; C09D 5/1625
20130101; A01N 25/02 20130101; C09D 5/14 20130101; B32B 2307/73
20130101; E04C 2/043 20130101; A01N 25/04 20130101; A01N 55/02
20130101; B32B 29/002 20130101; C09D 5/00 20130101; D21H 27/18
20130101; B32B 2250/03 20130101; B32B 2255/26 20130101; D21H 19/12
20130101; B32B 13/08 20130101; B32B 2255/24 20130101; B32B 2307/718
20130101; D21H 21/36 20130101; D21H 27/32 20130101; A01N 59/16
20130101; D21H 21/16 20130101; B32B 2255/12 20130101 |
International
Class: |
D21H 21/36 20060101
D21H021/36; A01N 55/02 20060101 A01N055/02; A01N 59/16 20060101
A01N059/16; A01N 25/04 20060101 A01N025/04; A01N 25/02 20060101
A01N025/02; C09D 5/14 20060101 C09D005/14; C09D 5/00 20060101
C09D005/00; D21H 19/12 20060101 D21H019/12; D21H 21/16 20060101
D21H021/16; B32B 29/00 20060101 B32B029/00; E04C 2/04 20060101
E04C002/04 |
Claims
1. A building material product comprising: a core comprising
gypsum, the core including a first face and a second and opposite
face; a first facing layer adhered to the first face and a second
facing layer adhered to the second face of the core, each of the
first and second facing layers comprising a paper layer; a water
repellent and mold inhibiting composition applied to at least one
of the facing layers, the water repellent and mold inhibiting
composition comprising: a water repellent agent; a mold inhibiting
agent; and a defoamer, the defoamer comprising an oil carrier and a
defoaming agent, the defoamer being present on the facing layer in
an amount greater than about 5 grams per MSF.
2. A building material product as defined in claim 1, wherein the
defoamer is present on the facing layer in an amount of from about
10 grams per MSF to about 50 grams per MSF.
3. A building material product as defined in claim 1, wherein the
oil carrier comprises a hydrocarbon oil.
4. A building material product as defined in claim 1, wherein the
oil carrier comprises mineral oil, vegetable oil, or a white
oil.
5. A building material product as defined in claim 1, wherein the
defoaming agent comprises hydrophobic silica particles.
6. A building material product as defined in claim 1, wherein the
water repellent and mold inhibiting composition further comprises a
wax.
7. A building material product as defined in claim 6, wherein the
wax comprises a stearamide wax, a paraffin wax, an ester wax, or a
fatty alcohol wax.
8. A building material product as defined in claim 1, wherein the
mold inhibiting agent comprises a pyrithione.
9. A building material product as defined in claim 8, wherein the
pyrithione comprises zinc pyrithione, the pyrithione being present
in the building material product as particles, and wherein at least
90% of the zinc pyrithione particles have a particle size of less
than 2 micron.
10. A building material product as defined in claim 1, wherein the
water repellent and mold inhibiting composition further contains
zinc oxide particles.
11. A building material product as defined in claim 1, wherein the
mold inhibiting agent comprises sodium pyrithione
12. A building material product as defined in claim 1, wherein the
water repellent agent comprises a silicone copolymer.
13. A building material product as defined in claim 1, wherein the
mold inhibiting agent is also present within the core.
14. A building material product as defined in claim 1, wherein both
the first facing layer and the second facing layer have been
treated with the water repellent and mold inhibiting
composition.
15. A building material product as defined in claim 1, wherein the
mold inhibiting agent is present in the facing layer at a
concentration of from about 50 ppm to about 10,000 ppm.
16. A building material product as defined in claim 1, wherein the
facing layer treated with the water repellent and mold inhibiting
composition has a basis weight of from about 38 lbs per MSF to
about 50 lbs per MSF.
17. A mold resistant paper product comprising: a paper layer; and a
water repellent and mold inhibiting composition applied to the
paper layer, the water repellent and mold inhibiting composition
comprising; a water repellent agent; a mold inhibiting composition
comprising a pyrithione; and a defoamer, the defoamer comprising an
oil carrier and a defoaming agent, the oil carrier comprising a
mineral oil, a vegetable oil, or a white oil, the defoamer further
comprising a defoaming agent, the defoaming agent comprising silica
particles, the defoamer being present on the paper layer in an
amount greater than about 5 grams per MSF, and wherein the paper
product has a Cobb water absorption value of less than about 100
grams per m.sup.2.
18. A paper product as defined in claim 17, wherein the water
repellent and mold inhibiting composition further comprises a
wax.
19. A mold inhibiting composition for use in paper products
comprising; a mold inhibiting agent and a defoamer, the defoamer
comprising an oil carrier and a defoaming agent, the defoaming
agent being present in the composition in an amount greater than
about 0.1% by weight.
20. A mold inhibiting composition as defined in claim 19, wherein
the mold inhibiting agent comprises zinc pyrithione, the mold
inhibiting composition further containing zinc oxide particles.
21. A process for producing a paper with mold and moisture
inhibiting properties comprising: forming a paper web from an
aqueous suspension of pulp fibers; applying to a side of the paper
web a water repellent and mold-inhibiting composition, the water
repellent and mold-inhibiting composition comprising: a water
repellent dispersion containing a water repellent agent, the water
repellent dispersion being present in the water repellent and mold
inhibiting composition in an amount from about 3% to about 10% by
weight; a mold inhibiting composition comprising a mold inhibiting
agent and a defoamer, the defoamer comprising an oil carrier and a
defoaming agent, the mold inhibiting composition being present in
the water repellent and mold inhibiting composition in an amount
from about 7% to about 20% by weight, the defoamer being present in
the water repellent and mold inhibiting agent in an amount of at
least about 0.1% by weight; and water; and thereafter drying the
paper web to form a paper product.
22. A process as defined in claim 21, further comprising the step
of laminating the paper product to a core comprising gypsum to form
a dry wall product.
23. A process as defined in claim 21, wherein the surface of the
paper web treated with the water repellent and mold inhibiting
composition has a Cobb water absorption value of less than about
100 grams per m.sup.2.
Description
RELATED APPLICATIONS
[0001] The present application is based on and claims priority to
U.S. Provisional Patent application Ser. No. 62/383,045 filed on
Sep. 2, 2016, which is incorporated herein by reference.
BACKGROUND
[0002] One of the most common ways of constructing walls and
barriers includes the use of inorganic wallboard panels or sheets,
such as gypsum wallboard, often referred to simply as "wallboard"
or "drywall." Wallboard can be formulated for interior, exterior,
and wet applications. The use of wallboard, as opposed to
conventional wet plaster methods, is often desirable because the
installation of wallboard is ordinarily less costly than
installation of conventional plaster walls.
[0003] Generally, wallboard is conventionally produced by enclosing
a core of an aqueous slurry of calcined gypsum and other materials
between two large sheets of board cover paper. Various types of
cover paper are known in the art, as are other types of facing
materials. After the gypsum slurry has set (i.e., reacted with the
water from the aqueous slurry) and dried, the sheet is cut into
standard sizes.
[0004] Many building material products such as wallboard are well
suited for absorbing moisture. For instance, moisture can be
absorbed by the facing materials and can also be absorbed by the
core material of wallboard. Moisture can be absorbed by these
materials especially in high humidity environments, such as in
bathrooms and basements. These building material products can also
become wet due to accidental spills or due to leaks in the plumbing
or leaks in the exterior of the building. Unfortunately, even small
amounts of moisture can stimulate the growth of many mold
organisms. Some mold organisms are sporulating fungal organisms
that, when they mature, spew out allergenic matter that can
detrimentally affect indoor air quality. Consequently, when mold
infestation occurs in a building or home, the owners typically have
to tear down walls and replace with new materials.
[0005] Various different anti-mold agents have been developed in
the past and incorporated into building material products, such as
wallboards. For instance, in the past, pyrithione has been used to
prevent mold growth on or in wallboards. For instance,
mold-resistant wallboards are disclosed in U.S. Patent Publication
No. 2006/0171976, in U.S. Patent Publication No. 2007/0082170 and
in U.S. Pat. No. 6,893,752, which are all incorporated herein by
reference. The anti-mold agents, for instance can be applied to the
facing materials during manufacture of the wallboard.
[0006] In addition to anti-mold agents, the facing materials, which
are typically made from a paper, are also typically treated with a
water repellent in order to reduce the water absorption properties
of the material. In one embodiment, for instance, the anti-mold
agent is combined with a water repellent in an aqueous dispersion
or in an oil and water dispersion and applied to the facing layers.
More particularly, these compositions are applied to the facing
layer while the facing layer is being produced in a wet laid paper
making process. For example, an aqueous dispersion containing one
or more anti-mold agents and one or more water repellents can be
applied to the facing layers after the facing layer has been formed
but prior to complete drying of the layer. In the past, however,
problems have been encountered in effectively incorporating the
anti-mold agent and the water repellent into the paper layer being
formed. For instance, problems have been experienced with excesses
foaming and frothing of the aqueous dispersion as the composition
is applied to the paper. The foaming of the composition cannot only
interfere with the process machinery, but can also prevent the
composition from being uniformly applied to the layer.
[0007] Prior use of defoamers have only created further problems.
Defoamers, for instance, can not only adversely interfere with the
other components but can significantly and adversely impact the
water absorption properties of the paper product. Consequently,
defoamers may serve to reverse the effects of the water
repellent.
[0008] Thus, a need currently exists for a process for effectively
applying an anti-mold agent and a water repellent to facing layers
and other paper products during manufacture of the products. In
particular, a need exists for an aqueous composition containing an
anti-mold agent and a water repellent that can be applied to paper
products during their formation that does not create excessive
foaming while also preserving the water repellent properties of the
paper layer. A need also exists for paper products made according
to the process and to laminated products containing the paper,
including building material products, such as wallboard.
SUMMARY
[0009] The present disclosure is generally directed to a water
repellent and mold inhibiting composition for use in building
material products that contains a mold inhibiting agent, such as
pyrithione, in combination with a water repellent agent. According
to the present disclosure, the water repellent and mold inhibiting
composition further contains a defoamer containing a defoaming
agent that has been found to not only reduce foam and frothing of
the composition when applied to a substrate but has also been found
not to interfere with the resulting water repellent properties of
the product.
[0010] In one embodiment, the present disclosure is directed to a
building material product. The building material product includes a
core that is comprised of gypsum. The core includes a first face
and a second and opposite face. At least one facing layer is
adhered to the first face, to the second face, or to both the first
face and the second face of the core. The facing layer may comprise
a pulp fiber substrate, such as a paper substrate. Each facing
layer, for instance, may comprise a paper having a basis weight of
from about 38 lbs per 1,000 ft.sup.2 to about 50 lbs per 1,000
ft.sup.2 (as used herein 1,000 ft.sup.2 is designated as "MFS"). In
accordance with the present disclosure, as least one of the facing
layers is treated with a water repellent and mold inhibiting
composition. The water repellent and mold inhibiting composition
comprises a water repellent agent, a mold inhibiting agent, and a
defoamer. The defoamer comprises an oil carrier and a defoaming
agent. In one embodiment, for instance, the defoaming agent may
comprise hydrophobic silica particles. The defoamer is present in
the water repellent and mold inhibiting composition in an amount of
at least about 0.08% by weight, such as in an amount of at least
about 0.1% by weight, such as in an amount of at least about 0.3%
by weight, such as in an amount of at least about 0.5% by weight.
For example, the defoamer may be present in the composition in an
amount up to about 10% by weight, such as in an amount up to about
5% by weight.
[0011] The oil carrier contained within the defoamer can comprise a
hydrocarbon oil. In various embodiments, the oil carrier can
comprise a mineral oil, a vegetable oil, or a white oil. The oil
carrier may comprise any suitable petroleum distillate. In addition
to the oil carrier and the defoaming agent, the defoamer may also
contain a wax. The wax may comprise a stearamide wax, a paraffin
wax, an ester wax, a fatty alcohol wax, or mixtures thereof. Once
applied to a facing layer, such as a paper product, the defoamer
can be present in the dried product in an amount greater that about
10 grams per MFS, such as from about 10 grams per MFS to about 50
grams per MFS.
[0012] Of particular advantage, it was discovered that the above
defoamer does not adversely interfere with the water repellent
agent and/or significantly affect the water repellent
characteristics of the resulting paper product. The water repellent
agent may be applied to the facing layer as an oil and water
dispersion containing a silicone copolymer.
[0013] The mold inhibiting agent included in the composition is
contained in at least one facing layer, in the core, or in both the
core and the facing layers. The mold inhibiting agent may comprise
a pyrithione.
[0014] The pyrithione present in the building material product may
comprise a metal pyrithione such as zinc pyrithione, sodium
pyrithione, or mixtures thereof.
[0015] The pyrithione may be in the form of particles, particularly
small particles. For instance, 100% of the particles may have a
particle size of less than 5 microns, while at least 90%, such as
at least 70% of the particles have a particle size of less than 2
microns, such as less than 1 micron.
[0016] In an alternative embodiment, a liquid pyrithione may be
used.
[0017] The pyrithione may be present in the paper product or in one
component of a building material product at a concentration of from
about 50 ppm to about 10,000 ppm, such as from about 100 ppm to
about 5,000 ppm, such as from about 500 ppm to about 3,500 ppm.
[0018] When the mold inhibiting agent comprises a pyrithione, the
mold inhibiting agent may be present in the composition in
combination with zinc oxide particles.
[0019] Building material products, such as wallboard, treated in
accordance with the present disclosure can have excellent
mold-resistant properties. For instance, when tested according to
ASTM Test D3273, wallboards treated in accordance with the present
disclosure can have a rating of greater than 7, such as greater
than 8, such as greater than 9, and can even have a rating of 10.
In addition, the one or more facing layers can have a Cobb water
absorption value of less than about 100 grams per m.sup.2, such as
less than about 90 grams per m.sup.2, such as less than about 80
grams per m.sup.2, such as less than about 70 grams per
m.sup.2.
[0020] In addition to a building material product, the present
disclosure is also directed to any suitable paper product treated
in accordance with the present disclosure. The paper product can
comprise a paper layer treated with a composition described above.
In addition to a facing layer of a building material product, the
paper product treated in accordance with the present disclosure may
comprise, for instance, a flooring felt, a roofing felt, an
insulation material, and the like. In general, any suitable paper
product may be treated in accordance with the present
disclosure.
[0021] The present disclosure is also directed to a mold inhibiting
composition as described above that may be used in conjunction with
a water repellent. The mold inhibiting composition for use in paper
products may comprise a mold inhibiting agent combined with a
defoamer as described above. The mold inhibiting composition may be
formulated as a concentrate that is then diluted and optionally
combined with a water repellant composition. When present as a
concentrate, for instance, the mold inhibiting composition may
contain water in an amount less than about 50% by weight, such as
in an amount less than about 40% by weight, such as in an amount
less than about 30% by weight, such as in an amount less than about
20% by weight.
[0022] The present disclosure is also directed to a process for
producing a paper with mold and moisture inhibiting properties. The
process includes the steps of first forming a paper web from an
aqueous suspension of pulp fibers. A water repellent and mold
inhibiting composition is applied to at least one side of the paper
web. In one embodiment, the composition is applied to the paper web
after the paper web has been formed but prior to final drying such
that the paper web is in a wet state or semi-dry state.
[0023] In one embodiment, the water repellent and mold inhibiting
composition comprises from about 3% to about 10% by weight of a
water repellent dispersion containing a water repellent agent and
from about 7% to about 20% by weight of a mold inhibiting
composition. The mold inhibiting composition can comprise an mold
inhibiting agent combined with a defoamer, wherein the defoamer
comprises an oil carrier, a defoaming agent and optionally a wax.
The defoaming agent, for instance, may comprise hydrophobic metal
oxide particles, such as silica particles. The defoamer is present
in the composition in an amount of at least about 0.08% by weight,
such as an amount of at least 0.3% by weight, such as an amount of
at least 0.5% by weight. The composition further contains water.
Water may be contained in the composition in an amount of at least
about 70% by weight, such as an amount of at least 80% by weight,
such as an amount of at least 85% by weight.
[0024] After the composition is applied to the paper web, the paper
web is dried to form a paper product. In one embodiment, the paper
product can be used to form a building material product containing
a core of gypsum. The resulting paper product can have a Cobb water
absorption value of less than about 90 grams per m.sup.2. The paper
product can have a basis weight of from about 38 lbs per MFS to
about 50 lbs per MFS.
[0025] Other features and aspects of the present disclosure are
discussed in greater detail below.
DETAILED DESCRIPTION
[0026] It is to be understood by one of ordinary skill in the art
that the present discussion is a description of exemplary
embodiments only, and is not intended as limiting the broader
aspects of the present disclosure.
[0027] Building materials, such as wallboards, are currently
treated with a mold inhibiting agent, such as a pyrithione complex.
The pyrithione complex may be contained in the core and also in the
facing layer made from paper. In some embodiments, the mold
inhibiting agent is combined with a water repellent and applied to
a product, such as the facing layer of a building material.
Problems, however, have been experienced in the past in excessive
foaming and frothing when the composition is applied. In this
regard, the present disclosure is directed to a mold inhibiting
composition that can be used in conjunction with a water repellent
that contains a mold inhibiting agent in combination with a
defoamer. More particularly, it was discovered that a defoamer
containing an oil carrier in combination with a defoaming agent has
been found to not only reduce or eliminate the formation of foam
when the product is used, but has also been found not to
significantly interfere with the water repellent properties of the
resulting product and/or with the efficacy of the water repellent
agent.
[0028] The water repellent and mold inhibiting composition of the
present disclosure can provide numerous benefits and advantages
when applied to a paper product. For instance, a paper product can
be imparted with water repellent properties and with mold
inhibiting properties through an easy to apply topical application
process in which foaming of the composition is minimized or
eliminated. By inhibiting the formation of foam, the composition of
the present disclosure, when applied to a substrate, would
generally be more uniform across or over the surface area of the
product. In addition, minimizing foam allows the process to achieve
or maintain a higher level of cleanliness that minimizes
contamination in the machinery and reduces or eliminates over
application of the composition and/or spills or messes that can
result from the formation of foam.
[0029] A water repellent and mold inhibiting composition made in
accordance with the present disclosure may be incorporated into any
suitable building product, such as wallboard. The combination of
components, when applied to a facing layer covering the gypsum, is
able to inhibit the growth of mold organisms for a prolonged period
of time while at the same time reducing the water absorption
properties of the substrate. Of particular advantage, when tested
according to ASTM Test D3270, the mold inhibitory composition of
the present disclosure is capable of demonstrating efficacy to
obtain a score greater than 7, such as greater than 8, such as
greater than 9, such as even a score of 10 where no visible growth
of mold is observed even when the wallboard product is subjected to
a humid environment. In addition, facings treated according to the
present disclosure can also display excellent water repellency
properties. For instance, the facing can have a Cobb water
absorption value of less than about 100 grams per m.sup.2, such as
less than about 90 grams per m.sup.2, such as less than about 80
grams per m.sup.2, such as less than about 70 grams per m.sup.2.
The Cobb water absorption value is generally greater than about 10
grams per m.sup.2, such as greater than about 20 grams per m.sup.2
in certain applications. Cobb testing can be completed at 3 minutes
using water at a temperature of 120.degree. F.
[0030] In addition to facing layers, however, it should be
understood that the composition of the present disclosure can be
used in a variety of other applications. For example, the
composition is well suited to treating any suitable paper product
particularly porous products. The composition, for instance, is
well suited for any application where a paper products needs water
repellent and antimicrobial properties. Other products that may be
treated in accordance with the present disclosure, for instance,
include flooring products, roofing felts, insulation products, and
the like.
[0031] As described above, wallboard is conventionally produced by
enclosing a core of an aqueous slurry of calcined gypsum and other
components between one or more facing layers. The facing layer may
comprise different materials. In one embodiment, the facing layer
contains pulp fibers. In this regard, the facing layer may comprise
a paper, such as a paperboard. In one embodiment, for instance, the
facing layer may be made from recycled pulp fibers, such as
recycled newsprint. The facing can have a basis weight of generally
greater than about 20 lbs per MFS, such as greater than about 25
lbs per MFS, such as greater than about 30 lbs per MFS, such as
greater than about 35 lbs per MFS, such as greater than about 38
lbs per MFS. The basis weight is generally less than about 60 lbs
per MFS, such as less than about 55 lbs per MFS, such as less than
about 50 lbs per MFS, such as less than about 48 lbs per MFS. In an
alternative embodiment, the facing layer may comprise starch or a
starch layer. In another embodiment, starch may be used to attach a
pulp containing facing layer to the core material.
[0032] The slurry used to make the core of wallboard comprises
calcined gypsum alone or in combination with various other
materials. In one embodiment, for instance, the core may further
include filler materials, binders, and the like.
[0033] Gypsum is typically obtained naturally from gypsum rock. The
gypsum rock is ground to a desired fineness and then undergoes
calcination. Calcination is performed by heating the gypsum rock in
order to remove moisture and produce calcium sulfate hemihydrate.
Calcium sulfate hemihydrate, when mixed with water, will set and
form the core material.
[0034] When producing wallboard, an aqueous slurry of calcined
gypsum and other components can be continuously deposited between
two facing layers. The slurry can contain any calcined gypsum
including calcium sulfate hemihydrate, calcium sulfate anhydrite or
both. Calcium sulfate hemihydrate can produce at least two crystal
forms, the alpha and beta forms. Beta or alpha calcium sulfate
hemihydrate may be used.
[0035] In some embodiments, additives are included in the gypsum
slurry to modify one or more properties of the final product. Such
additives can include starches, defoamers, surfactants, dispersants
and the like. Such additives can include naphthalene sulfonates and
wax emulsions. A set accelerator may also be present comprising
calcium sulfate dihydrate co-ground with sugar and heated to
250.degree. F. (121.degree. C.) to caramelize the sugar.
[0036] A trimetaphosphate compound can be added to the gypsum
slurry in some embodiments to enhance the strength of the product
and to reduce sag of the set gypsum. The concentration of the
trimetaphosphate compound can be from about 0.1% to about 2.0%
based on the weight of the calcined gypsum. Exemplary
trimetaphosphate salts include sodium, potassium or lithium salts
of trimelaphosphate.
[0037] In addition, the gypsum composition optionally can include a
starch, such as a pregelatinized starch or an acid-modified starch.
The inclusion of the pregelatinized starch increases the strength
of the set and dried gypsum cast and minimizes or avoids the risk
of paper delamination under conditions of increased moisture (e.g.,
with regard to elevated ratios of water to calcined gypsum). The
pregelatinized starch can be added to the mixture used to form the
set gypsum composition such that it is present in an amount of from
about 0.5% to about 10% percent by weight of the set gypsum
composition.
[0038] Gypsum panels are typically greater than 1/8 inch in
thickness. The gypsum panels can be from about 3/8 inch (9.5 mm) to
about 2 inches (51 mm), from about 3/4 inch (19 mm) to about 11/4
inch (32 mm) or from about 1/2 inch (13 mm) to about 1 inch (25 mm)
in thickness.
[0039] In accordance with the present disclosure, a water repellent
and mold inhibiting composition may be applied to one of the facing
layers, may be applied to both facing layers, or may be applied to
both the facing layers and the aqueous slurry that provides the
core.
[0040] The composition of the present disclosure can include the
combination of mold inhibiting composition with a water repellent
composition or dispersion. Alternatively, the mold inhibiting
composition can be applied separately from the water repellent
composition albeit to the same substrate at approximately the same
time.
[0041] The mold inhibiting composition generally comprises an
aqueous solution, dispersion or suspension that contains a mold
inhibiting agent and a defoamer. In accordance with the present
disclosure, a defoamer is selected that not only reduces foam
during application of the product but also does not interfere with
the water repellent agent and/or adversely impact the water
absorption characteristics of the substrate in a substantial
manner.
[0042] The defoamer for use in the present disclosure comprises an
oil carrier and a defoaming agent. The oil carrier, for instance,
may comprise any suitable hydrocarbon oil and/or petroleum
distillate. Particular oils that may be used include mineral oil,
vegetable oil, a white oil, or any other oil that is insoluble in
the foaming medium.
[0043] In one embodiment, the defoamer is silicone-free or contains
relatively low amounts of silicone, such as silicone oil. In
various embodiments, the defoamer may contain silicone in
relatively low amounts, such as less than about 10% by weight, such
as less than about 2% by weight, such as less than about 1% by
weight, such as less than about 0.5% by weight, such as less than
about 0.1% by weight.
[0044] In addition to the oil carrier, the defoamer contains a
defoaming agent. In one embodiment, the defoaming agent comprises
metal oxide particles. For example, in one embodiment, the
defoaming agent comprises silica particles, such as hydrophobic
silica particles. The silica particles can be present in the
defoamer in an amount generally less than about 20% by weight, such
as in an amount less than about 15% by weight, such as in an amount
less than about 10% by weight, such as in an amount less than about
2% by weight. The silica particles are generally present in an
amount greater than about 0.1% by weight, such as in an amount
greater than about 0.5% by weight, such as in an amount greater
than about 0.8% by weight, such as in an amount greater than about
1% by weight.
[0045] In addition to an oil carrier and a defoaming agent, the
defoamer may contain various other ingredients and components. In
one embodiment, for instance, the defoamer may contain a wax. The
wax, for instance, may comprise a stearamide wax, a paraffin wax,
an ester wax, and/or a fatty alcohol wax. In one particular
embodiment, the defoamer comprises an ethylene bis stearamide wax.
The wax is generally present in the defoamer in an amount less than
about 10% by weight, such as in an amount less than about 2% by
weight, such as in an amount less than about 1% by weight. The wax
is generally present in an amount greater than about 0.1% by
weight.
[0046] In order to effectively eliminate foaming and/or frothing
during application of the mold inhibiting agent and the water
repellent, the defoamer can be present in the composition generally
in an amount greater than about 0.08% by weight, such as in an
amount greater than about 0.3% by weight, such as in an amount
greater than about 0.5% by weight, such as in an amount greater
than about 0.9% by weight. The defoamer is generally present in an
amount less than about 10% by weight, such as in an amount less
than about 7% by weight, such as in an amount less than about 5% by
weight, such as in an amount less than about 3% by weight, such as
in an amount less than about 2% by weight.
[0047] The defoamer is combined with a mold inhibiting agent to
form a mold inhibiting composition. In general, any suitable mold
inhibiting agent can be contained in the composition or mixture of
mold inhibiting agents. In one embodiment, the mold inhibiting
agent comprises a pyrithione. As used herein, a pyrithione includes
pyrithione salts, and particularly polyvalent metal salts of
pyrithione. For instance, pyrithione salts can be formed from
polyvalent metals such as magnesium, barium, bismuth, strontium,
copper, zinc, cadmium, zirconium and mixtures thereof.
[0048] Pyrithione is known by several names, including 2
mercaptopyridine-N-oxide; 2-pyridinethiol-1-oxide (CAS Registry No.
1121-31-9); 1-hydroxypyridine-2-thione and 1
hydroxy-2(1H)-pyridinethione (CAS Registry No. 1121-30-8). The
sodium derivative (C.sub.5H.sub.4 NOSNa) is known as sodium
pyrithione (CAS Registry No. 381173-2). Pyrithione salts are
commercially available from Arch Chemicals, Inc., such as Sodium
OMADINE.TM. or Zinc OMADINE.TM..
[0049] The pyrithione may be present in the mold inhibiting
composition in different forms. In one embodiment, for instance,
the pyrithione may comprise an aqueous dispersion, such as an
aqueous dispersion containing zinc pyrithione. The pyrithione may
be contained in the aqueous dispersion as particles, and
particularly small particles. For instance, the particles can have
a particle size such that 100% of the particles have a particle
size of less than about 5 microns and at least about 50% of the
particles, such as at least about 70% of the particles have a
particle size of 2 microns or less, such as 1 micron or less.
Particle size can be measured using a laser scattering particle
size analyzer, such as a HORIBA LA 910 particle size analyzer.
[0050] The particles can be present in the aqueous dispersion in an
amount greater than about 30% by weight and in an amount less than
about 70% by weight. In one embodiment, for instance, the particles
are present in an amount from about 40% to about 60% by weight. The
aqueous dispersion can also contain various other components, such
as a dispersant and/or a viscosity control agent. The pH of the
aqueous dispersion can be from about 6.5 to about 8.5. In an
alternative embodiment, the pH can be greater such as from about 9
to about 11 depending upon the ingredients contained in the
dispersion.
[0051] In an alternative embodiment, the pyrithione may be present
in the composition as a solution. For instance, the solution may
contain sodium pyrithione. The solution may contain pyrithione in
an amount greater than about 25% by weight, such as from about 30%
by weight to about 70% by weight. In one embodiment, for instance,
the solution can contain pyrithione in an amount from about 35% by
weight to about 45% by weight. The solution can have a pH of from
about 8.5 to about 10.5 and can contain various other components in
addition to the pyrithione and water. For instance, in one
embodiment, the solution can contain an amine, which may increase
the pH to from about 11 to about 12.
[0052] The pyrithione is added to the mold inhibiting composition
in an amount sufficient to inhibit the growth of microorganisms,
particularly mold. As mentioned above, the pyrithione can be added
to one or more facing layers of wallboard and/or to the core. The
concentration of pyrithione added to a component of the wallboard
can depend upon various different factors. In general, pyrithione
is added at a concentration of greater than about 50 ppm and up to
a concentration of about 10,000 ppm. More particularly, the
pyrithione concentration is generally greater than about 100 ppm,
such as greater than about 200 ppm, such as greater than about 300
ppm, such as greater than about 400 ppm, such as greater than about
500 ppm. The concentration is generally less than about 5,000 ppm,
such as less than about 3,500 ppm, such as less than about 2,000
ppm. In one embodiment, the concentration of pyrithione in one
component of the wallboard can be from about 100 ppm to about 5,000
ppm, such as from about 500 ppm to about 3,500 ppm.
[0053] The mold inhibiting composition, in addition to a
pyrithione, can also contain one or more potentiators. As used
herein, a potentiator is any compound, ion, element, oligomer, or
polymer that is capable of increasing the efficacy of the
pyrithione. The potentiator may comprise, for instance, a metal
chelator, a metal salt which may or may not be a metal chelator, a
long chain aliphatic amine, a natural extract, and the like. The
long chain aliphatic amine can have a carbon chain length from
about 12 carbon atoms to about 60 carbon atoms, such as from about
12 carbon atoms to about 40 carbon atoms, such as from about 12
carbon atoms to about 28 carbon atoms. Examples of long chain
aliphatic amines that may be used in accordance with the present
disclosure include oleylamine, dodecylamine, or mixtures
thereof.
[0054] The potentiator may also comprise an enolic ketone, such as
an unsaturated enolic ketone. An example of an enolic ketone is
tropolone. For example, in one embodiment, a tropolone complex may
be used as a potentiator. The tropolone complex may comprise a
metal complex, such as a complex with zinc or copper. Tropolone can
be synthetically made or can be obtained naturally from cedar
wood.
[0055] In another embodiment, a copper salt is used as a
potentiator, such as a copper amine. For instance, in one
embodiment, the potentiator comprises copper ethanolamine.
[0056] In still another embodiment, the potentiator may comprise a
metal salt of dehydroacetic acid (DHA). For instance, in one
embodiment, the potentiator comprises a zinc salt chelate of
DHA.
[0057] In still another embodiment, the potentiator may also
comprise a surfactant. For instance, an amine oxide surfactant may
be used, such as a cocamine oxide surfactant. In one particular
embodiment, the surfactant comprises
N-alkyl(C.sub.12-C.sub.16)dimethylamine oxides.
[0058] In one embodiment, the mold inhibiting composition may also
contain a zinc salt. The zinc salt, for instance, may optionally
form a complex with the pyrithione, especially zinc pyrithione. The
zinc salt may comprise, for instance, zinc oxide. Zinc oxide may be
present in the composition in an amount generally from about 0.001%
to about 10% by weight. Other zinc salts that may be present in the
composition include zinc salts of organic acids, zinc salts or
inorganic acids, zinc hydroxide, and the like. The zinc compound
may have multiple purposes. For instance, the zinc compound may
increase the efficacy of the pyrithione, provide resistance to UV
energy, or prevent the pyrithione from discoloring over time. In
various embodiments, the zinc compound may be present in an amount
from about 0.01% to about 3% by weight, such as in an amount from
about 0.02% to about 0.5% by weight.
[0059] The above mold inhibiting composition can be combined with a
water repellent composition to form a water repellent and mold
inhibiting composition for treating various substrates while
inhibiting the formation of foam and froth. Various different types
of water repellent compositions may be used. In one embodiment, for
instance, the water repellent composition may comprise a silicone
emulsion. The water repellent composition, for instance, may
contain a water repellent agent comprising a silicone. In one
embodiment, the water repellent agent may comprise a curable,
silicone copolymer. For example, once dried on a substrate, the
water repellent agent may comprise a cured siloxane.
[0060] In one embodiment, in addition to a water repellent, the
water repellent composition may contain a surfactant, such a
non-ionic surfactant, in an oil and water type emulsion. The
silicone or water repellent agent can be present in the composition
in an amount generally greater than about 5% by weight, such as in
an amount greater than about 10% by weight, such as in an amount
greater than about 15% by weight, such as in an amount greater than
about 20% by weight, such as in an amount greater than about 25% by
weight, such as in an amount greater than about 30% by weight. The
water repellent agent is generally present in the water repellent
composition in an amount less than about 70% by weight, such as in
an amount less than about 60% by weight, such as in an amount less
than about 55% by weight, such as in an amount less than about 50%
by weight.
[0061] The water repellent composition may be combined with the
mold inhibiting composition to form a water repellent and mold
inhibiting composition for application to various substrates, such
as facing layers for wallboards and other building products. The
water repellent and mold inhibiting composition can contain the
water repellent composition in an amount greater than about 2% by
weight, such as in an amount greater than about 3% by weight, such
as in an amount greater than about 4% by weight. The water
repellent composition is generally contained in the water repellent
and mold inhibiting composition in an amount less than about 15% by
weight, such as in an amount less than about 10% by weight, such as
in an amount less than about 8% by weight.
[0062] The mold inhibiting composition can generally be present in
the water repellent and mold inhibiting composition in an amount
greater than about 5% by weight, such as in an amount greater than
about 7% by weight, such as in an amount greater than about 8% by
weight. The mold inhibiting composition is generally present in the
overall composition in an amount less than about 30% by weight,
such as in an amount less than about 25% by weight, such as in an
amount less than about 20% by weight, such as in an amount less
than about 15% by weight, such as in an amount less than about 13%
by weight.
[0063] The water repellent and mold inhibiting composition can also
contain substantial amounts of water. Water can be present in the
composition in an amount greater than about 70% by weight, such as
in an amount greater than about 75% by weight, such as in an amount
greater than about 80% by weight, such as in an amount greater than
about 85% by weight. Water is generally present in the composition
in an amount less than about 95% by weight, such as in an amount
less than about 90% by weight.
[0064] The water repellent and mold inhibiting composition of the
present disclosure can be used in numerous applications. In one
embodiment, the composition can be applied to a paper product as
the product is being formed. In order to prevent the composition
from foaming, significant amounts of a particular defoamer are
present that not only inhibit foaming but also do not interfere
with the water repellency properties of the final product. Once the
product is dried, for instance, the defoamer can be present on the
product in an amount greater than about 5 grams per MFS, such as
greater than about 10 grams per MFS, such as greater than about 20
grams per MFS, such as greater than about 25 grams per MFS, such as
greater than about 30 grams per MFS. The defoamer is generally
present in amount less than about 200 grams per MFS, such as less
than about 100 grams per MFS, such as less than about 80 grams per
MFS, such as less than about 70 grams per MFS, such as less than
about 60 grams per MFS, such as less than about 50 grams per
MFS.
[0065] In one embodiment, when treating a paper product with the
water repellent and mold inhibiting composition of the present
disclosure, the process includes the step of first forming a paper
web from aqueous suspension of pulp fibers. In addition to pulp
fibers, the paper web may contain various other components. For
instance, the paper web can contain filler particles and/or
synthetic fibers. In one embodiment, the aqueous suspension of
fibers is deposited on to a forming surface from a head box. The
forming surface may comprise a porous material, such as a screen
that allows liquids to drain from the fibers. The embryonic web can
be subjected to various pressing steps and/or vacuum in order to
drain fluids from the web and to allow the web to form.
[0066] In one embodiment, after the paper web is formed but prior
to final drying, the water repellent and mold inhibiting
composition of the present disclosure can be applied to the web.
For example, in one embodiment, the water repellent and mold
inhibiting composition can be applied to the web using a water box
or any other suitable device. The consistency of the paper web
during application of the composition can vary depending upon
various factors. In one embodiment, the composition can be applied
to the paper web while the paper web has a solids content of
greater than about 80%, such as greater than about 85%, such as
greater than about 90%, such as from about 90% to about 95%. In an
alternative embodiment, however, the composition can also be
applied to the paper product when the paper product contains
greater amounts of water. For instance, in other embodiments, the
solids content of the paper web can be between about 25% to about
60%, such as from about 25% to about 40%.
[0067] The amount of composition applied to the paper web can vary
depending upon the particular application and the desired result.
In general, the water repellent and mold inhibiting composition as
described above can be applied to the paper web in an amount
greater than about 1,000 grams of fluid per MFS, such as greater
than about 1,200 grams of fluid per MFS, such as greater than about
1,500 grams of fluid per MFS, such as greater than about 1,600
grams of fluid per MFS. The composition is generally applied in an
amount less than about 5,000 grams of fluid per MFS, such as in an
amount less than about 3,000 grams of fluid per MFS, such as in an
amount less than about 2,500 grams of fluid per MFS, such as in an
amount less than about 2,000 grams of fluid per MFS.
[0068] After application to the paper web, the paper web is dried
and further processed as desired depending upon the end use
application. In one embodiment, the dried paper web can contain the
water repellent agent in an amount from about 22 grams per MFS to
about 110 grams per MFS, such as from about 26 grams per MFS to
about 70 grams per MFS, such as from about 26 grams per MFS to
about 50 grams per MFS. The mold inhibiting agent may be present on
the dried paper web in an amount from about 30 grams per MFS to
about 250 grams per MFS, such as from about 50 grams per MFS to
about 150 grams per MFS, such as from about 55 grams per MFS to
about 100 grams per MFS. The defoamer, on the other hand, may be
present on the dried web in an amount from about 1 gram per MFS to
about 50 grams per MFS, such as from about 12 grams per MFS to
about 30 grams per MFS, such as from about 12 grams per MFS to
about 20 grams per MFS.
[0069] In one particular application, the paper product formed in
accordance with the present disclosure may comprise a facing for a
building material product, such as a wallboard. Wallboards
typically include two facings, a first facing that is exposed when
the product is installed, and a second facing that faces the
interior of the wall. The exposed facing may have a white
appearance and may be configured to accept paint or wallpaper. The
facing that faces the interior of the wall, on the other hand, may
have a grey appearance. Both facings may have a basis weight of
generally from about 30 lbs/MFS to about 50 lbs/MFS. Once treated
in accordance with the present disclosure, in addition to having
excellent anti-mold properties, the facings also are water
resistant. For instance, the facings can have a Cobb water
absorption value of less than about 90 grams per m.sup.2, such as
less than about 80 grams per m.sup.2, such as less than about 175
grams per m.sup.2.
[0070] In one embodiment, after the facings are formed, the facings
are wound into a roll and then fed into a process for forming the
drywall. In particular, an aqueous suspension of drywall material
comprising gypsum can be deposited in between the two facing layers
and dried. The resulting drywall can then be cut into sheets having
desired dimensions for use in constructing new houses and
buildings.
[0071] The present disclosure may be better understood with
reference to the following examples.
Examples
[0072] The following experiments were conducted to show some of the
benefits and advantages of the present disclosure. Various
different water-based compositions containing a water repellent and
a mold inhibiting agent were formulated and tested with various
different defoamers for their foaming properties. The water
repellent composition comprised a silicone emulsion containing a
curable siloxane. The mold inhibiting composition, on the other
hand, contained pyrithione as a mold inhibiting agent. The
pyrithione was present in combination with zinc oxide.
[0073] The base formulation of the composition is provided in Table
1 below. The water repellent was a non-ionic surfactant-stabilized
aqueous emulsion of a curable modified silicone copolymer. The mold
inhibiting compositions included a dispersion 1 (Z1) which
contained 37% zinc pyrithione (ZPT) and 12% zinc oxide by weight
while dispersion 2 (Z2) contained 48% zinc pyrithione by weight.
Additional Z1 and Z2 samples containing 0.1% and 1.0% of one of
three defoamers were also formulated. Defoamer 1 (D1) was an
oil-based silicia emulsion/dispersion in accordance with the
present disclosure. D1 also contained an ethylene bis stearamide
wax. The oil carrier comprised mineral oil. Defoamer 2 (D2) was a
mixture of polysiloxanes and hydrophobic solids in polyglycols; and
Defoamer 3 (D3) contained a mixture containing polysiloxanes and
glycol components.
TABLE-US-00001 TABLE 1 Base formulations % % Solids Solids % %
Compo- Compo- Contribu- ZPT ZPT Component nent nent tion, % (Z1)
(Z2) Tap water 85.3 -- -- -- -- Water Repellant 4.9 44 2.2 -- --
Mold inhibiting 9.8 50 4.9 4.7 3.7 Dispersion (Z1 = 48% active) (Z2
= 38% active) Total Solids 7.1
[0074] Fluid samples were prepared by weighing approximately 23
grams of the mold inhibiting dispersion (Z1 for test samples 1, 2,
3, 4 and Z2 for samples 5, 6, 7, and 8) and 12 grams of the water
repellent into about 200 mL of tap water. Defoamer was added to
test samples 2-4 and 6-8 in amounts sufficient to reach target
levels of about 1000 ppm in the test solution. Control sample 1 was
prepared by adding approximately 12 grams of the water repellent to
228 grams of tap water. Control samples 3-4 were prepared by
weighing approximately 0.25 grams of defoamer and 12 grams of the
water repellent into 228 mL of tap water.
[0075] Fluid samples were placed into a 50.degree. C. oven for
about an hour prior to testing or application to roughly simulate
the mill application conditions. In addition, the fluid samples
containing defoamer were also placed in the oven for one month to
assess any potential impact on dispersion consistency and/or
stability.
[0076] Foaming/frothing potential was evaluated by applying shear
to a known volume of test fluid (about 210 to 245 mL in a 400-mL
plastic beaker) for 1 minute using a 1-inch diameter Cowles blade
and a Dispermat high speed mixer run at 2500 rpm. The change in
volume of the fluid sample (i.e. the foam or froth) was immediately
measured (in mL) after the mix period using a graduated cylinder,
and the time required for the foam/froth to dissipate was
determined.
[0077] The following results were obtained:
TABLE-US-00002 TABLE 2 Foaming Characteristics of Fluid Samples
Foaming Character- Emulsion/Dispersion Sample istics.sup.1
Compatibility/stability Control 1 +++ In WB fluid.sup.2 In ZPT
Dispersion Control 2 (w/0.1% D1) - Excellent N/A Control 3 (w/0.1%
D2) - Excellent N/A Control 4 (w/0.1% D3) ++ Excellent N/A Sample 1
(Z1) ++ Good N/A Sample 2 (Z1 w/0.1% D1) - Excellent B Sample 3 (Z1
w/0.1% D2) ++ Poor C Sample 4 (Z1 w/0.1% D3) + Fair B Sample 5 (Z2)
+ Fair N/A Sample 6 (Z2 w/0.1% D1) + Good A Sample 7 (Z2 w/0.1% D2)
+ Poor B Sample 8 (Z2 w/0.1% D3) ++ Fair A .sup.1Foaming
characteristics: +++ = relatively stable foam. .gtoreq.80 mL foam
height, 90% dissipation times of >10 min.; ++ = moderate amount
of less stable foam, 20 to 40 mL foam height, 90% dissipation time
5 to 15 min.; + = low foam, .ltoreq.5 mL foam height, 90%
dissipation times of 3 min,; - = no foam .sup.2Compatibility:
Excellent = little or no residues; Good = slight amount of residue
noted; Fair = moderate amount of residue noted; Poor = significant
residues observed 3. Stability: A = no separation or thickening of
dispersion; B = slight separation and/or thickening of dispersion;
C = significant separation and/or thickening of dispersion
TABLE-US-00003 TABLE 3 Antifoam Efficacy Test Results 400 mL
beaker, high speed disperser unit with 1-inch Cowles blade, 500 mL
graduated cylinder Samples placed in a 50.degree. C. oven for 1
hour, 230 to 240 mL of fluid were poured into the beaker, mixed for
1 minute at 2000 rpm, then decanted immediately into graduated
cylinder. Foam height and dissipation time (90%) were measured. 90%
Average foam Dissipation Residue Sample No. height, mL Time, min.
Formation Control 1 80 10 to 20 None Control 2 (w/0.1% D1) 0 n/a
None Control 3 (w/0.1% D2) 0 n/a None Control 4 (w/0.1% D3) 20 10
to 15 None Sample 1 (Z1) 5 <3 Moderate Sample 2 (Z1 w/0.1% D1) 5
<3 Slight Sample 3 (Z1 w/0.1% D2) 5 <3 Significant Sample 4
(Z1 w/0.1% D3) 25 5 to 10 Moderate Sample 5 (Z2) 35 5 to 10 Slight
Sample 6 (Z2 w/0.1% D1) 0 n/a None Sample 7 (Z2 w/0.1% D2) 30 3 to
5 Significant Sample 8 (Z2 w/0.1% D3) 20 5 to 10 Moderate Residue
Formation: None = <1% of calculated total solids content Slight
= estimated to be .ltoreq.10% of calculated total solids content
Moderate = estimated to be 10 to 30% of calculated total solids
content Significant = estimated to be >30% of calculated total
solids content
[0078] Following foam testing, the test fluids were applied to A4
sized pieces (8.27.times.11.69 in =0.7 ft.sup.2=21.times.30 cm=630
cm.sup.2) of sample paper, consisting of manila machine finished
paper (basis weight of about 43 lbs./MSF) as board face sheet and
newsprint paper (basis weight of about 46 lbs./MSF) as board back
sheet. Using foam applicators, the fluids were applied to
completely wet the designated side of each paper sheet specimen.
The excess fluid was quickly wiped off of the paper's surface using
an absorbent paper towel, and the specimen was then weighed
immediately to determine the amount of wet fluid applied. The
targeted pick-up rate for the emulsion/dispersion treatment fluid
was 3.8 lbs./MSF (1725 grams fluid per MSF paper=64 to 81 grams
ZPT/MSF). Thus, the target application amount of fluid to apply to
each A4-sized paper specimens (on the finished or cylinder side of
sheet) was 1.3 grams (which would be equivalent to approximately
1725 grams fluid per MSF, or 1.725 grams/ft.sup.2, or 0.002
g/cm.sup.2).
[0079] Water absorption (in g/m.sup.2) of the treated paper samples
was measured using the Cobb test. Using Fibro ACT (Automatic Cobb
Tester), three minute dynamic Cobb measurements were made on
replicates of each sample using water heated to approximately
50.degree. C.
TABLE-US-00004 TABLE 4 Water Absorptivity Properties of Treated
Paper Increase in Cobb Value, g/m2 (% .DELTA.) Sample Machine
Finished Newsprint Control 1 -- -- Control 2 (w/0.1% D1) 3.52 (6%)
1.55 (3%) Control 3 (w/0.1% D2) 8.34 (15%) 14.58 (25%) Control 4
(w/0.1% D3) 3.40 (6%) 12.18 (21%) Sample 1 (Z1) -- -- Sample 2 (Z1
w/0.1% D1) 0.97 (2%) 0.53 (<1%) Sample 3 (Z1 w/0.1% D2) 10.67
(18%) 7.07 (11%) Sample 4 (Z1 w/0.1% D3) 5.27 (9%) 0.73 (1%) Sample
5 (Z2) -- -- Sample 6 (Z2 w/0.1% D1) -0.20 (0%) 0.97 (1%) Sample 7
(Z2 w/0.1% D2) 5.43 (9%) 5.24 (8%) Sample 8 (Z2 w/0.1% D3) -0.63
(0%) 5.07 (8%)
[0080] Samples 2-4 and 6-8 were then reformulated containing 1% by
weight of the corresponding defoamer product. It was observed that
the (D1) defoamer produced the least amount of residues and was
compatible with the water repellent. The (D3) defoamer product, on
the other hand, caused some separation and/or gelling.
[0081] During testing, it was noted that the water repellent
produced significant amounts of foam. Compositions containing both
the water repellent and the mold inhibiting composition also
exhibited stable foam. Defoamer (D1) in accordance with the present
disclosure significantly and dramatically reduced or eliminated
foaming in all fluids. This result was surprising and unexpected in
view of the performance of the other defoamer products. Of
particular advantage, the (D1) defoamer in accordance with the
present disclosure also preserved the water repellent properties of
the resulting paper.
[0082] These and other modifications and variations to the present
invention may be practiced by those of ordinary skill in the art,
without departing from the spirit and scope of the present
invention, which is more particularly set forth in the appended
claims. In addition, it should be understood that aspects of the
various embodiments may be interchanged both in whole or in part.
Furthermore, those of ordinary skill in the art will appreciate
that the foregoing description is by way of example only, and is
not intended to limit the invention so further described in such
appended claims.
* * * * *