Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
/~
t~3t91
Attorney Docket No. 9429
COMPOSIT~ F~TT WArr r~IN~RS
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to materials which are used to line
walls or ceilings to provide a new surface for the application of
paint or decorative wall covering. In particular, the invention
has to do with wall liner products comprising wet-laid, composite
felt sheets and structures incorporating such products wherein
the imperfections in the walls and/or ceilings of the structures
are covered by the wall liner.
The Prior Art
Wall liners are relatively thin, lightweight sheet materials
which are used in the construction industry to cover existing
walls or ceilings which have imperfections and therefore are
unsuitable, aesthetically or physically, for the application of
paint or decorative wall covering.
The imperfections which are covered by wall liners typically
include 1) unsuitable surfaces which can be defined as including
excessive layers of decorative wall covering and/or paint, greasy
surfaces and the like, and 2) irregular surfaces which can be
defined as including roughness, cracks and holes caused by
settling, unevenness created by water damage, the grouting in
existing blocks or tile, the grooves or grain in paneling,
textured paint and the like. Thus the term "cover imperfections
3 1 ~ 1
as used in this specification means that the underlying
imperfections are aYoided because they are masked by the wall
liner, i.e., a more suitable new surface is provided for the
application of paint or decorative wall covering and the
underlying contour of surface irregularities is hidden or
substantially smoothed over.
While wall liners are not a substitute for structural
building materials which are used to make or replace a wall,
repair a structurally unsound wall or cover large openings, they
can be used in many applications where wall boards such as
plasterboard or sheetrock might otherwise have been used to cover
irregular surfaces. The wall liners can provide an alternative
in many applications to materials which are thicker, heavier and
more difficult to handle and install, are more expensive, and
require further surface preparation such as taping and spackling.
Methods and devices for repairing cracks and holes in walls
are known. U. S. Patent No. 4,989,385 to McCullough, for
example, describes a device for repairing a hole in plasterboard.
The device is formed of a relatively thin, stiff coverboard
having an insulation board of lesser dimension adhered to the
rear surface. The insulation board is sized to fit into the hole
and the coverboard is secured to the undamaged portion of the
wall. This kind of device may be useful for repairing a
relatively large hole in a wall which is otherwise smooth and in
good condition, or it might, for example, be used to repair a
portion of an irregular wall before a wall liner is used to cover
the entire wall.
Presently available wall liner products made of fiberglass
are fla~eproof and dimensionally stable and generally do not
follow the contour of underlying imperfections. They also bend
at corners without cracking. However, the fiberglass products
are associated with irritation to the s~in of installers caused
by bits of glass that break off during handling of the material
and penetrate the skin.
Another type of wall liner product is made of dry-laid paper
but it is not stiff enough to cover surface irregularities,
particularly in the presence of moisture, because it tends to
follow the contour of the underlying surface.
We have now developed a new wall liner product comprised of
a wet-laid, composite, felt sheet material which is not
associated with the skin irritation caused by fiberglass
products. Our product provides an excellent new surface for the
application of paint or decorative wall covering and it is
sufficiently stiff to cover the irregularities in underlying
walls and ceilings. Our product also maintains such sufficient
stiffness in the presence of moisture.
Wet-laid felt products have been manufactured for many years
and have been used in various applications for gaskets,
substrates for other materials (e.g., sheeted floor and wall
coverings), roofing felt and the like.
Current production methods for making composite sheets of
felt are a part of the papermaking art and can employ handsheet
~1~31 ~i
.
forming apparatus or, more commonly, continuous papermaking
equipment such as a Fourdrinier machine, a cylinder machine,
suction machines such as a Rotaformer, millboard equipment and
modified versions of such equipment. The production methods are
variously set forth in the patent literature and a good narration
is provided in U. S. Patent No. 4,225,383, the specification of
which is incorporated herein by reference.
In general terms, the process involves preparing an aqueous
dispersion of a water-dispersible fiber or blend of fibers (e.g.,
cellulose, synthetics and fiberglass) and inorganic materials
such as clays. These materials are blended in a high speed mixer
such as a hydropulper. The aqueous dispersion is then
transferred to a blending tan~ provided with a continuous mixer.
A latex binder is added to the blending tank followed by a
flocculant or coagulant which is added in sufficient quantity to
colloidally destabilize the resulting mixture. When the mixture
has been destabilized a fibrous agglomerate is formed, which is
known in the art as a furnish. The furnish is transferred to a
continuously mixed holding tank known as a machine chest. From
the machine chest, the furnish is applied to a woven mesh belt
(also called a wire or forming fabric). A flocculant can be
added to the furnish prior to application of the furnish to the
belt in order to enhance water drainage and solids retention.
water is drained from the furnish, the da~p felt then is removed
from the belt and it is dried. Coatinqs can be applied to the
surfaces of the dried or partially dried felt and the end product
~ ~3~
is taken up on a roll.
Construction materials which are made from felt are well
known. These materials employ flexible felt, and roofing felt
(tar paper) is an example. In many applications, flexible felt
is used as a component of construction materials such as a
substrate for floor covering or wall covering and, while such
materials generally should be dimensionally stable during the
manufacturing process, they can absorb water and swell without
detriment to the appearance or function of the covering material
when the material is installed on a surface.
Wall liner products must have certain characteristics which
have not previously been associated with the felt products used
in construction materials. A wall liner product must be
sufficiently water resistant to maintain dimensional stability
when coated with aqueous adhesives and latex paints and,
preferably, should be strippable (i.e., have sufficient split
strength to be stripped off without damaging the undersurface).
In applications where the wall liner is used to cover irregular
surfaces, it must also be sufficiently stiff to cover
imperfections in underlying walls and ceilings and the stiffness
must be maintained when the product is subjected to moisture.
Otherwise the product will tend to follow the contour of the
underlying surface and it will not meet the objective of creating
a suitable ~ew surface for the application of paint or decorative
wall covering.
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SU~HARY OF THE INV~N~ION
The wall liner product of the invention is comprised of a
wet-laid, composite, felt sheet material which can be used to
line walls or ceilings to provide a new surface for the
application of paint or decorative wall covering. The product is
dimensionally stable in the presence of moisture and it is
strippable. In a preferred embodiment, the wall liner product
also has sufficient stiffness in the presence of moisture to
cover irregular surfaces in the underlying walls and ceilings.
Thus, the preferred wall liner of the invention can be used over
imperfect walls or ceilings having unsuitable surfaces, irregular
surfaces or both.
Moisture resistance can be imparted to the wall liners of
the invention by appropriate formulation of the furnish or by
coating the surfaces of the felt or, preferably, formulating the
furnish and coating the surfaces.
The furnish used to make the felt in the preferred
embodiment is formulated to obtain sufficient stiffness in the
end product.
Conventional papermaking equipment such as a Fourdrinier
machine can be used to manufacture the product.
The wall liner product is relatively thin and lightweight
and it can be adhered to a wall or ceiling using conventional
techni~ues and materials such as adhesives which are used to
apply decorative wall covering materials. Thus a laminate is
made comprising a wall or ceiling having a wall liner adhered
319~
thereto. The wall liner then can be painted or overlayed with a
decorative wall coverinq.
All percentages set forth herein are by weight unless
otherwise designated.
BRIEF DESCRIPTION OF TH~ DRAWINGS
Figure 1 is a fragmentary cross sectional view of a laminate
of the invention illustrating a wall liner adhered to an
irregular wall wherein the outer surface of the wall liner has
been painted.
Figure 2 is a fragmentary cross sectional view of a laminate
of the invention illustrating a wall liner adhered to an
irregular wall wherein the outer surface of the wall liner has
been overlayed by decorative wall covering.
Figure 3 is a fragmentary cross sectional view of a laminate
of the invention illustrating a wall liner adhered to a wall
which has excessive layers of paint and/or decorative wall
covering thereon.
Figure 4 is a schematic diagram illustrating the preferred
manufacturing process of the invention.
DETAILpn D8SCRIPTION OF THE INVENTION
In order for a wall liner product to meet the objective of
creating a suitable new surface on walls or ceilings for the
application of paint or decorative wall covering, it must be
sufficiently water resistant to maintain dimensional stability
when coated with aqueous adhesives and latex paint. The wall
liner also preferably should have sufficient split strength to be
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. _ .
stripped off without damaging the undersurface. This character-
istic is referred to as "strippability" in the decorative wall
covering art. In the preferred embodiment of the invention, the
wall liner also must be stiff enough to cover irregular surfaces.
The preferred product also must retain such stiffness after it
has been subjected to moisture because the adhesives used to
install the wall liner contain water, and latex paints and
adhesives used to apply decorative wall covering contain water.
There are various ways to define sufficient stiffness and
the term stiffness as used in the present specification
inherently includes the characteristic of dimensional stability
in the presence of moisture. (A wall liner which is intended to
cover irregular surfaces and which is not dimensionally stable in
the presence of moisture will tend to follow the contour of the
underlying surface and, therefore, it will not meet the stiffness
requirement of the preferred embodiment of the present
invention.) A stiffness sufficient to cover an opening in a wall
or ceiling which is in the shape of a circle having a diameter of
about one inch would meet the objectives of the preferred
embodiment of the invention as long as such stiffness is
maintained in the presence of moisture and the wall liner does
not substantially follow or, preferably, does not follow at all
the contour of the opening.
A recognized test for 5tiffness i5 Taber Stiffness and the
test can follow ASTH D747 or TAPPI T489. (TAPPI stands for
Technical Association of the Pulp and Paper Industry, One
~S3~ 9-~
Dunwoody Park, Atlanta, GA 30341 U.S.A. and their test methods
are published in ~APPI Test Methods. ) A recognized test for
water absorption is TAPPI T441. When the preferred wall liner
product of the invention has been totally immersed in water for
about two minutes and then subjected to a Taber Stiffness test it
should have a minimum Machine Direction (~MD") Taber Stiffness of
20, most preferably a minimum of 31 (for a product having a
caliper of 15 mils), and a minimum Cross Machine Direction ("CD")
Taber Stiffness of 14, most preferably a minimum of 1~ (for a
product having a caliper of 15 mils). The more flexible wall
liner of the invention which can be used to cover unsuitable
surfaces, as that term is defined herein, should also maintain a
certain level of stiffness (a type of dimensional stability) in
the presence of moisture. A minimum MD Taber Stiffness of 6 and
a minimum CD Taber Stiffness of 2 is suitable following immersion
in water for about two minutes.
Characteristics of the wall liner product which can be
measured and miqht be used to set specifications for the product
are summarized below for the flexible, preferred and most
preferred embodiments.
3 ~ ~ 1
Specifica~ion
Characteristic/ Most
- Test Procedure Test Type Flexihle Preferre~ Preferred
Dry Stiffness MD Taber Min.20 42 51
ASTM D747 or CD Taber Min.14 36 45
TAPPI T489
Water Absorption (2 minutes)
TAPPI T441
FFl Grams Max. 2 0.5 0.15
WF2 Grams Max. 2 0.5 O.lS
Wet Stiffness3
ASTM D747 or MD Taber Min. 6 20 31
TAPPI T489 CD Taber Min. 2 14 17
Smoothness4 FF Bendtsen Max.2000 900 775
WF Bendtsen Max.2000 925 800
Tear Strength MD Elmendorf Min.80 130 160
TAPPI T414
CD Elmendorf Min.80 150 190
Dry Tensile MD lb/inch Min.10 25 33
ASTM D828
CD lb/inch Min. 8 15 20
Wet Tensile MD lb/inch Min. 5 9 13
ASTM D829
CD lb/inch Min. 3 5 7.5
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1. FF refers to felt face, the side of the felt which was not on
the wire during manufacture.
2. WF refers to wire face, the side of the felt which was on the
wire during manufacture.
3. Taber Stiffness on a sample following total immersion of the
sample in water for about 2 minutes.
4. Measured on a Bendtsen Smoothness and Porosity Tester, Model
6, available from Testing Machines, Inc., 400 Bayview Ave.,
Amityville, NY 11701 U.S.A.
~lS~191
A wall liner should be relatively thin and lightweight so
that it can easily be handled and installed. A thickness (also
referred to herein as "calipern) of fro~ about 0.004 to about
0.15 inches, as measured according to TAPPI T411, and a density
from about 25 to about 100 pounds per cubic foot ("lb~ft3) is
suitable. In a preferred embodiment of the present invention the
wall liner has a caliper from about 0.010 to about 0.04 inches
and a density from about 40 to about 85 lb/ft3.
The wall liner product of the present invention is a
composite felt material which comprises:
(a) from about 4 to about 100 percent, preferably from
about 6 to about 30 percent, of a water
dispersible fiber;
(b) from about 0 to about 95 percent, preferably from
about 50 to about go percent, of an inorganic
filler;
(c) from about 0 to about 30 percent, preferably from
about 8 to about 20 percent, of a binder;
(d) from about 0 to about 1 percent, preferably from
about 0.1 to about 0.3 percent, of a flocculant or
flocculant and coagulant; and
(e) an optional water proofing outer coating.
Stiffness can be imparted to the composite felt material of
the invention by employinq binders which are inherently stiff
such as styrene butadine rubbers ("SBR") having a high styrene
content, latexes having high crosslinking density and the like.
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Such binders are added to the furnish in an amount from about 8
to about 20 percent. Other means of imparting stiffness include
employing stiffer fibers and higher amounts of stiffer fibers.
High filler levels also can increase stiffness.
Water resistance is imparted to the conposite felt material
of the invention either by adding a water resisting comp~sition
to the furnish, coatinq both sides of the felt with a water
resisting composition or, preferably, both adding a water
resisting composition to the furnish and coating both sides of
the felt with a water resisting composition.
Suitable water resisting compositions for addition to the
furnish, if needed in addition to the binder (which also can be
selected to impart water resistance), include rosin size,
cationic starch, polymeric materials such as olefins, waxes, and
HERCON 70 ketene dimer (available from Hercules Incorporated,
Hercules Plaza, Wilmington, DE 19844 U.S.A.) and if such
compositions are employed they generally are added to the furnish
in an amount from about 0.05 to about 10 %.
Suitable water resisting compositions for coating the felt
include polymeric starches, polymeric latexes, olefins, waxes and
HERCON 70, and if such compositions are employed they are applied
to the felt by conventional means such as by a rod coater, blade
coater, air knife, size press or the like.
Figure 1 illustrates a laminate of the invention wherein
wall 1 having an irregular surface l-S has been covered by wall
liner 2. Wall liner 2 is adhered to irregular surface l-S by
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adhesive 3. Surface 2-S of the wall liner is substantially
smoother than irregular surface l-S and comprises a suitable new
surface for the application of paint or decorative wall covering.
A layer of paint 4 is adhered to the surface 2-S of the wall
liner.
Figure 2 il,lustrates a laminate of the invention wherein
wall 1 having an irregular surface 1-S has been covered by wall
liner 2. Wall liner 2 is adhered to irregular surface 1-S by
adhesive 3. Decorative wall covering 5 is adhered to the surface
2-S of the wall liner by adhesive 3a, which optionally can be the
same adhesive as adhesive 3.
Figure 3 illustrates a laminate of the invention wherein
wall 1 has a surface 1-U which is unsuitable for the application
of paint or decorative wall covering because the wall has
numerous layers of paint and/or decorative wall covering
collectively designated as l-L. Unsuitable walls of this kind
may be uneven and/or soft, might not accept paint, might blister
upon the application of paint or primer, or have other
characteristics that would be detrimental to the appearance of a
decorative surface finish or make it impossible to satisfactorily
apply a decorative surface finish. The wall liner 2 is adhered
to unsuitable surface 1-U by adhesive 3. The surface 2-S has a
decorative surface finish 6 applied thereto. The decorative
surface finish may be paint such as that illustrated in Figure 1
or it may be a decorative wall covering adhered with an adhesive
such as that illustrated in Figure 2.
2 ~
- The wall liner product is manufactured using conventional
- equipment for felt manufacture such as a Fourdrinier machine. In
a preferred embodiment of the invention the product is made in
the continuous process illustrated schematically in Figure 4.
Referring to Figure 4, water is added to a high speed mixer
such as hydropulper 10, and, with continuous mixing, the water
dispersible fiber is admixed with the water in an amount from
about 1 to about 2.5 percent and the inorganic filler is admixed
in an amount from about 4 to about 8 percent to prepare a first
dispersion. Then the first dispersion is pumped to a blending
tank 11 along with additional water to reduce solids content to
about 3.5 to about 6 percent, and with continuous mixing the
binder is added in an amount from about 8 to about 20 percent,
based on dry solids. This is followed by adding the coagulant in
an amount from about 0.06 to about 0.18 percent, based on dry
solids, to form a fibrous agglomerate. The fibrous agglomerate
then is pumped to a mixing tank such as machine chest 12 and it
is continuously mixed and held in the machine chest until it is
needed. Then flocculant is added at 13 in an amount from about
0.04 to about 0.12 percent, based on dry solids, to complete
preparation of the furnish and the furnish is applied to the
continuous mesh belt 14.
The upper surface of the mesh belt moves continuously in the
direction of arrow 15 and water drains from the furnish through
the mesh belt in the direction of arrows 16 until a wet felt 17
is formed having sufficient strength to be lifted from the belt.
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(Drain water can be collected and recycled as indicated.) The
wet felt is pressed by press rolls 18 to squeeze moisture out of
the wet felt and the pressed felt 17a is taken through a
continuous dryer comprised of steam heated drums 19. The dried
felt 17b is coated with water proofing material on the wire face
by passing it over and contacting it with rod coater 20. The
coating is dried with a flame type infrared dryer 21 and then the
felt face of dried felt 17b is coated with the same water
proofing material at rod coater 22 in the same manner as at rod
coater 20. The coated product 17c is finally dried in dryer 23
and then taken up on roll 24.
The fiber used according to the invention is any water-
insoluble, natural or synthetic water-dispersible fiber or blend
of such fibers. Usually water dispersibility is provided by a
small amount of ionic or hydrophilic groups or charges which are
of insufficient magnitude to provide water-solubility. Either
long or short fibers, or mixtures thereof, are useful. Many of
the fibers from natural materials are anionic, e.g., wood pulp.
Some of the synthetic fibers are treated to make them slightly
ionic, i.e., anionic or cationic. Glass fiber, chopped glass,
blown glass, reclaimed waste papers, cellulose from cotton and
linen rags, mineral wool, synthetic wood pulp such as is made
from polyethylene, straws, ceramic fiber, nylon fiber, polyester
fiber and similar materials are useful. Particularly useful
fibers are the cellulosic and lignocellulosic fibers commonly
known as wood pulp of the various kinds from hard wood and soft
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wood such as stone ground wood, steam-heated mechanical pulp,
chemimechanical pulp, semichemical pulp, and chemical pulp.
Specific examples are unbleached sulfite pulp, bleached sulfite
pulp, unbleached sulfate pulp and bleached sulfate pulp.
The inorganic fillers which are used in the practice of the
invention are finely-divided, essentially water-insoluble,
inorganic materials. Such materials include, for example,
titanium dioxide, amorphous silica, zinc oxide, barium sulfate,
calcium carbonate, calcium sulfate, aluminum silicate, clay,
magnesium silicate, diatomatious earth, aluminum trihydrate,
magnesium carbonate, partially calcined dolomitic limestone,
processed volcanic mineral, magnesium hydroxide, and mixtures of
two or more of such materials.
The binder used according to the invention is a film-
forming, water-insoluble, organic polymer which is natural or
synthetic and may be a homopolymer, a copolymer of two or more
ethylenically unsaturated monomers or a mixture of such polymers.
Particularly for ease of processing to make the product and for
limiting the loss of pollutants to the surroundings, it is
generally advantageous that the polymer is in the form of a
latex, i.e., an aqueous colloidal dispersion. Representative
organic polymers are acrylics, polyvinyl acetates, ethylene vinyl
acetates, natural rubber, the synthetic rubbers such as
styrene/butadiene rubbers, isoprene rubbers, butyl rubbers and
nitrile rubbers and other rubbery or resinous polymers of
ethylenically unsaturated monomers which are film-forming,
2~.631~1
preferably at room temperature or below, although in a particular
instance a polymer may be used which is film-forming at the
temperature used in preparing that sheet- Non-film-forming
polymers may be used in blends provided that the resulting blend
is film-forming. Polymers which are made film-forming by the use
of plasticizers also may be used. The binders preferably have
some ionic hydrophilic groups but must be devoid of sufficient
non-ionic colloidal stabilization which would interfere with
formation of the fibrous agglomerate- Such non-ionic, colloidal
stabilization could be provided by non-ionic emulsifiers or by
the presence of copolymerized monomers having the kinds of
hydrophiliC groups that are found in non-ionic emulsifiers, for
example, hydroxyl and amide groups. Thus, if monomers having
such hydrophilic groups are polymerized constituents of the latex
polymers, such monomers will be present in small proportion such
as less than about 10~, usually less than about 5% of the polymer
weight for best results. Also, while very small amounts of non-
ionic emulsifiers can be tolerated in some compositions, their
use ordinarily is not advantageous and they should not be used in
amounts sufficient to interfere with the destabilization step of
the process.
The flocculant is a water-dispersible, preferably water-
soluble, ionic compound or polymer, i.e., compounds or polymers
having a positive or a negative charge. The flocculant selected
for use according to the invention ordinarily will have a charge
opposite in siqn to the binder. If the binder has a negative
~l63l9 ~
charge, the flocculant will have a positive (cationic) charge and
vice versa. However, when combinations of two or more
flocculating agents are used, not all of them are necessary are
opposite in charge to the initial charge of the latex.
RepresentatiVe flocculants are cationic starch; water-
soluble, inorganic salts such as alum, aluminum sulfate, calcium
chloride and magnesium chloride; and ionic latex having a charge
opposite in sign (+) to that of the binder latex, e.g., a
cationic latex or an anionic latex; water-soluble, ionic,
synthetic, organic polymers such as polyethylenimine and various
ionic polyacrylamides such as carboxyl-containing poly-
acrylamides; copolymers of acrylamide with dimethylamino-
ethylmethacrylate or diallyldimethyl ammonium chloride;
polyacrylamides modified other than by copolymerization to have
ionic groups; and combinations or two or more of the above, added
simultaneously or in sequence. Quaternized polyacrylamide
derivatives are especially advantageous when the binder which is
used is anionic. Polymeric flocculants are preferred because
they are more efficient, tend to produce less water sensitive
products and provide better shear stability of the furnish. A
suitable flocculant is NALCO 7527, available from Nalco Chemical
Company, One Nalco Center, Naperville, IL 60583 U.S.A.
18
~3~ 9i
-
EXA~PLFS
~xample I
A handsheet forming apparatus was used to determine the
relative effects of GenFlo 2554 and GenFlo 2544 latex binders on
stiffness of the resultant felt handsheets. (The GenFlo binders
were obtained from GenCorp., Akron, Ohio, U.S.A.)
Mixtures of HERCON 70, the latex binders, and the Nalco 7527
flocculant were prepared as follows:
HERCON 70 5 ml in 95 ml water
GenFlo 2554 61 ml in 39 ml water
GenFlo 2444 56 ml in 44 ml water
Nalco 7527 2.7 grams in 1 liter water
The prepared mixtures were allowed to condition at ambient
temperature for 30 minutes before usinq.
Seven handsheet samples were prepared using the following
basic formulation:
Bleached Kraft Pulp 14%
Fiberglass 1.5%
~aolin Clay 30%
Aluminum Silicate Clay 30%
Processed Volcanic Mineral 10.5%
Latex Binder 14~
Flocculant as required
HERCON 70 mixture as specified
Quantities of the various materials used to prepare the handsheets
were as follows:
~Qmponent Wei~ht in gram~
Handsheet Number: 1 2 3 4 5 6 7
Bleached Kraft Pulp 2.95 2.9S 2.95 2.95 2.95 2.95 2.95
Fiberglass 0.4 0.4 0.4 0.4 0.4 0 4 0 4
Kaolin Clay 6.0 6.0 6.0 6.0 6.0 6.0 6.0
Aluminum Silicate
Clay 6.0 6.0 6.0 6.0 6.0 6.0
Processed Volcanic
Mineral 2.1 2.1 2.1 2.1 2.1 2.1 2.1
Calcium Carbonate - - - - - - 6.0
2554 mixture 10.0 10.0 10.0 10.0 10.0
2544 mixture - - - - - 10.0 10.0
HERCON 70 mixture 10.0 - 20.0 5.0 30.0 20.0 15.0
Flocculant mixture 65 60 65 65 65 60 70
For each handsheet, the bleached kraft was added to approximately
500 ml water in an ordinary household blender and then dispersed at
low speed for approximately 1 minute. The fiberglass, clays, and
processed mineral were then added to the blender and this mixture was
dispersed at high speed for approximately 2 minutes. The mixture was
then transferred to a 2 liter beaker and was diluted with water to a
total volume of 1400 ml. While continuously mixing with a propeller
type agitator running at slow speed, the appropriate latex mixture and
~ ~3~9 i
then the HERCON 70 mixture were added to the beaker. Flocculant
mixture was then added to the beaker until all latex was coagulated,
as indicated by a change from cloudy to clear water.
The mixture was then transferred to a standard 8 inch x 8 inch
laboratory handsheet mold and agitated to a uniform distribution of
the materials. At this point, the water was drained from the mixture
and the time required to drain was recorded. The resultant wet sheet
was removed from the wire mesh of the mold, pressed between layers of
blotter paper, and then dried.
The following measure~ents were made for each handsheet:
Handsheet Number: 1 2 3 4 5 6 7
Drain Time 2.5 2.3 2.4 2.2 2.1 2.0 1.5
Caliper in mils 21 22 21 21 16 24 23
Sheet Weight - grams 18.7 19.1 19.3 19.4 12.0 18.8 19.2
Sheet Density - lb/ft3 60.4 58.8 61.8 62.5 51.4 52.9 57.3
Solids Retention - % 93.5 95.6 96.4 97.0 60.2 93.8 96.2
Taber stiffness was measured on samples of each handsheet both at
ambient conditions and after exposure to nearly 100% relative humidity
at room temperature for 24 hours. The high humidity exposure was
achieved by suspending the samples above water in a closed container.
Stiffness was measured using a Hodel 104-1 Taber V5 Stiffness Gauge.
Readings were taken at a deflection of 15 , with no range weight on
the lower pendulum. The results were as follows:
~ - v
Taber Stiffness
(in taber stiffness units)
HandsheetAt AmbientAfter Humidity HERCON 70
Number Conditions ~xposure % ChangeAddition
2 30 11 63 o
4 32 11 65 5 ml
1 28 12 57 10 ml
3 25 9 64 20 ml
12 5 58 30 ml
6 96 30 70 20 ml
7 77 26 66 15 ml
This data was interpreted as follows:
1) The stiffer GenFlo 2544 latex binder yielded a significantly
stiffer felt sheet, in both high and low humidity conditions, than
the more flexible GenFlo 2554 latex binder.
2) Substitution of calcium carbonate filler for aluminum
silicate clay filler decreased the stiffness of the felt sheet.
~31~ '
_,
~ E~m~le II
A production trial was run using the process described in
Figure 4 and the following felt furnish:
81eached Kraft Pulp 18%
Kymene 557H Resin1 0.25%
Fiberglass 1.5%
Kaolin Clay 27%
Aluminum Silicate Clay 31%
Processed Volcanic Mineral 9%
GenFlo 2554 Latex 14%
The latex was coagulated with Hydraid 777 (Calgon Corp.,
P.o. Box 1346, Pittsburgh, PA 15230 U.S.A.) in the blending
tank. Nalco 7527 flocculant was added to the slurry between the
machine chest and the wire mesh forming screen to further
agglomerate the slurry before forming the felt. HERCON 70 sizing
emulsion was added to the slurry at a rate of 900 ml/minute at a
point ahead of the flocculant addition.
Before beginning the run, the wire face coater was charged
with 6 gallons of HERCON 70 in approximately 50 gallons of water.
The felt face coater was not used for this trial. The mixture
consumed in coating the felt was continuously replenished with
water, but HERCON 70 was replenished in increments of 10 gallons
____________________
1. Available from Hercules Incorporated, Hercules Plaza,
Wilmington, DE 19894 U.S.A.
~ ~3~
added to the coater reservoir- The first HERCON 70 addition was
made after running for 8 minutes and a second addition was made
15 minutes into the run. Also after 15 minutes run time the
continuous addition of HE~CON 70 to the slurry was increased from
900 to 1800 ml/minute.
Samples of the felt produced were taken at the take up roll
at 2, 10, 15, 20, and 25 minutes into the run.
The water absorptivity of these samples was tested using an
expedient procedure simulating TAPPI Test Method T441 - Water
Absorptiveness of Si2ed (Nonbibulous) Paper and Paperboard (also
known as the Cobb Test). In this procedure, 1 ml of water was
placed on the surface of a 2 inch square felt sample and allowed
to sit for 10 minutes. The water was then poured off of the
sample and the surface was blotted dry with absorbent paper. The
felt sample was weighed before and after exposure to the water
and the absorptivity was calculated as the change in weight due
to the absorbed water.
The following data was obtained:
Weight Gain in Grams
Sample Sampling Coated Uncoated
Number Point Face Face
1 2 min. 0.52 0.52
2 10 min. 0.47 0.52
3 15 min. 0.02 0.38
4 20 min. 0.00 0.38
25 min. 0.00 0.37
~3~ 9 i
The decrease of water absorbed by the uncoated face from 0.52 to
0.38 ~rams indicates that the increase in the continuous addition
of HERCON 70 to the slurry from 900 to 1800 ml/~inute was
effective in reducing the water absorptivity of the felt.
Similarly, the decrease from 0.52 to 0 grams water absorbed by
the coated face indicates that, at a concentration greater than
15 gallons HERCON 70 in 35 gallons water, a coated application of
HERCON 70 is extremely effective in reducing water absorptivity.
The data suggests that the coated application is the preferred
manner of imparting water resistance to the product.
Example III
A production trial was run using the process described in
Figure 4 and the felt furnish described in Example II. The latex
was coagulated and flocculant was added to the slurry as
described in Example II, but HERCON 70 was not added to the
slurry before forming the felt on the wire mesh forming screen.
Before beginning the run, the wire face coater was charged
with 15 gallons of HERCON 70 and approximately 35 gallons of a
coating mixture of the following composition:
Polyvinyl Alcoholl16.5%
Defoamer 0.5%
Boric Acid 1.5%
Water 81.5%
____________________
1. AIRVOL 203 S, available from Air Products and Chemicals Inc.,
7201 Hamilton Boulevard, Allentown, PA 18195 U.S.A.
~31~1
~ Also before beginning the run, the felt face coater was charqed
with 10 gallons of HERCON 70 and approximately 40 gallons of a
coating mixture of following composition:
Styrene-butadiene latexl 22.0%
Talc 8.4%
Alginate thickener 1.9%
Benzimidazole type mildewcide0.5%
Water 67.2%
This composition is calculated on the basis of the quantities of
the materials combined together to produce the coating mixture.
The mixture consumed in coating the felt was continuously
replenished with water and controlled quantities of the coating
mixture used in the respective coaters. The HERCON 70, however,
was not added to the master batches of the respective coating
mixtures, but was replenished in increments of 5 gallons added to
the coating reservoir. These additions were made in the
following sequence:
____________________
1. A carboxylated styrene butadiene latex having a glass
'transition temperature of -4 C.
'~l S31~ ~
HERCON 70 Additions
~in g~llons~
Wire Face Felt Face
~i~e into Run Coater Co~ter
Initial Charge 15 10
20 min. 5 none
27 min. none 5
30 min. 5 none
40 min. 5 none
45 min. End of Run
The water absorptivity of samples from this run was tested
using the modified Cobb Test procedure described in Example II.
The following data was obtained.
Weight Gain in qrams
Sampling Wire Felt
Point Face
Run Start 0.27 0.00
Run End 0.26 0.07
Example II Retest 0.03 0.36 (Uncoated)
The following conclusions were drawn from this data:
1) The water exclusion property of HERCON 70 was confirmed.
This conclusion is supported by the result that water absorption
on all coated faces was less than that of the uncoated face of
the Example II specimen.
2) A component of the wire face coating mixture
counteracted the water exclusion effect of HERCON 70. The result
that absorption is substantially less on the felt face than on
2~i319L
the wire face, even though HERCON 70 additions to the wire coater
were double those to the felt face coater supports this
conclusion.
Pieces of material made during this trial were pasted to
wooden boards with grooves cut into the boards in two different
sizes (1) 10/32" wide 3/22" deep (2) 7/32" wide 3/22" deep.
Clear/strippable ready mix adhesive (Golden Harvest GH-14) was
used. The adhesive was applied to the wall liner with a cloth
roller and the wall liner was then applied to the board and
smoothed with a wallpaper smoothing brush. The finished covering
was then painted with 2 coats interior white flat latex paint.
Appearance
Side Pasted Before After Repeat
to Board Paint Paint Stri~pability Strippability
wire side Good not Good not does not does not
deformed deformed strip strip
felt side Good not Good not Good Good
deformed deformed release release
Example IV
A handsheet forming apparatus was used to determine the
effect of fiberglass quantity and diameter on stiffness of the
resultant felt handsheets.
Mixtures of GenFlo 2544 latex binder and the Nalco 7527
flocculant were prepared as follows:
GenFlo 2544 56 ml in 44 ml water
Nalco 7527 2.7 grams in 1 liter water
~16~
The prepared mixtures were allowed to condition at ambient
temperature for 30 minutes before using.
Ten handsheet samples were prepared based on the following
formulation:
Bleached Kraft Pulp 14%
Fiberglass variable
Kaolin Clay 30%
Aluminum Silicate Clay 30%
Processed Volcanic Mineral 10.5%
Latex Binder 14%
Flocculant as required
Quantities of fiberglass added to the basic formulation were
calculated to achieve a base level of an approximately constant
number of fibers and a second constant number of fibers equal to
twice the base level.
The types and quantities of glass fibers used to produce the
respective handsheets were as follows:
29
Fiher~l~ss Ty~e
Handsheet Length Diameter Quantity
Number Inches Microns %
1 0.25 6.5 0.8
2 0.25 6.5 1.6
3 0.25 7.5 1.05
4 0.25 7.5 2.1
0.125 9.0 l.S
6 0.125 9.0 3.0
7 0.25 9.0 1.5
8 0.25 9.0 3,0
9 0.25 11.0 1.25
0.25 11.0 2.5
The handsheets were prepared as described in Example I,
except that no HERCON 70 was used.
The following measurements were made for each handsheet:
Handsheet Number: 1 2 3 4 5 6 7
Caliper in mils 17 20 20 22 19 25 21
Sheet Density - lb/ft3 58.0 52.9 55.4 50.7 54.3 49.0 56.0
Solids Retention - % 70.9 78.5 78.6 82.1 79.6 88.9 86.0
Handsheet Number: 8 9 10
Caliper in mils 23 22 23
Sheet Density - lbJft3 55.2 58.0 58.4
Solids Retention - % 92.4 92.7 97.5
~1~3~
_,,
Taber stiffness was measured on samples of each handsheet,
as described in Example I, bot~ at ambient conditions and after
immersion in water for one hour. The results, which represent
the average of four measurements, were as follows:
Fiberglass Type
Handsheet Length Diameter Quantity Taber Stiffness
Nu~ber Inches Microns % Dry ~Ç~
1 0.25 6.5 0.8 22 4.5
2 0.25 6.5 1.6 30 7.0
3 0.25 7.5 1.05 32 4.5
4 0.25 7.5 2.1 30 7.0
0.125 9.0 1.5 34 6.0
6 0.125 9.0 3.0 47 12.7
7 0.25 9.0 1.5 38 8.0
8 0.25 9.0 3.0 42 10.0
9 0.25 11.0 1.25 38 7.5
0.25 11.0 2.5 49 12.5
These results show that fiberglass contributed to felt
stiffness and that this contribution increased with both
increasing fiber concentration and with increasing fiber
diameter. This contribution remained in effect under humid or
wet conditions, although the effect was reduced significantly.
Thus, if desired, the felt sheet could be made stiffer by
incorporating larger diameter glass fibers in the furnish, by
increasing the concentration of glass fibers, or through
combinations of higher concentrations and larger diameter fibers.
2l~3l~ l
A comparison of the relative effects of fiber length
(Handsheets 5, 6, 7 and 8) indicated that the effect of doubling
fiber concentration is essentially the same as the effect of
doubling fiber diameter without changing concentration.
F.xan~ple V
A production trial was run using the process described in
Figure 4 and the felt furnish described in Example II. The latex
was coagulated and flocculant was added to the slurry as
described in Example II, but, as in Example III, HERCON 70 was
not added to the slurry before forming the felt on the wire mesh
forming screen.
Before beginning the run, a coating mixture of the following
composition was prepared and charged to both the wire face and
felt face coaters:
Styrene-butadiene latex 17.5%
Talc 6.6%
HERCON 70 20 . 8%
Alginate thickener 1.5%
Benzimidazole type mildewcide0.35%
Water 53. 2 %
This composition is calculated on the basis of the quantities of
the materials combined together to produce the coating mixture.
The mixture consumed in coating the felt was continuously
replenished with water and controlled quantities of the coating
mixture used in the respective coaters. HERCON 70 additions to
~ ~ 6 ~
the coater reservoir, as described in Examples II and III, were
not made.
The water absorptivity of samples from this run was tested
using the modified Cobb Test procedure described in Example II.
The following data was obtained:
~eight Gain in Gram~
Wire Felt
E~ E~
0.01 o.oo
Other samples from the run were tested for water absorptivity
using TAPPI Test Procedure T441. The following results were
obtained:
Weight Gain in Grams
Exposure Time Wire Felt
Minutes Face Face
2 0.17 0.16
0.16 0.24
0.28 0.33
These results indicated that the desired uniformity in water
absorptivity, with respect to the two felt faces, had been
achieved.
' 2~6~19t
Ex~m~le VI
Taber stiffness tests were conducted on three samples of
felt and the stiffness modulus was calculated on all samples.
The formula for modulus calculation also was used to determine
what the Taber stiffness would be at a caliper of 15 mils for
samples having a caliper different from 15 mils.
The following formula was used:
E = 0.006832 X X (Taber Stiffness Units)
wd3.D
where:
E = stiffness in flexure in pounds per square inch
w = specimen width in inches
d = specimen caliper in inches
D = deflection of specimen converted to radians
Samples 1 and 2 were representative of the more flexible
wall liner of the invention and Sample 3 was the preferred wall
liner of the invention made according to Example V. Dry
stiffness was measured according to ASTM D747 and wet stiffness
was measured according to ASTH D747 following total immersion of
the sample in water for 2 minutes. All samples were 1.5 inches
wide. All Taber Stiffness values are expressed in Taber
Stiffness Units, and Modulus (E) values are expressed in pounds
per square inch.
34
2 1 ~
The results were as follows:
~m~le/C~ er Dry .~tiffness Wet Stiffnes~
1/17 mils
Taber Stiffness 38.0 19.8 6.5 3.3
Modulus 134,550 70,225 23,015 11,805
Taber @ 15 mils 26.1 13.6 4.5 2.3
2/20 mils
Taber Stiffness 40.8 23.3 8.3 2.5
Modulus 88,790 50,740 18,120 5,435
Taber ~ 15 mils 17.2 9.8 3.5 1.1
3/15 mils
Taber Stiffness 51.0 45.0 31.0 17.0
Modulus 262,800 231,950159,800 87,600
