CA2163191A1

CA2163191A1 - Composite felt wall liners

Info

Publication number: CA2163191A1
Application number: CA002163191A
Authority: CA
Inventors: Douglas Charles Woerner; Kenneth Jay Faust; Michael Harold Labianca; Matthew John Waite
Original assignee: Tarkett Inc
Current assignee: Tarkett Inc
Priority date: 1995-11-17
Filing date: 1995-11-17
Publication date: 1997-05-18

Abstract

A wall liner product comprised of a wet-laid, composite, felt sheet material which is used to line walls or ceilings to provide a new surface for the application of paint or decorative wall covering. The product is a relatively thin, light-weight sheet which is sufficiently water resistant to maintain dimensional stability when coated with aqueous adhesives and latex paints. In the preferred embodiment, the wall liner also has sufficient stiffness in the presence of moisture to cover irregular surfaces in walls or ceilings. Laminates are prepared comprised of a wall or ceiling having a wall liner adhered thereto. A further layer or layers are added to the laminate when the wall liner is painted or overplayed with decorative wall covering.

Description

/~
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.

~fi~91 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 ~ 3J~91 . _ .

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 Water Absorption (2 minutes) 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 CD Elmendorf Min.80 150 190 Dry Tensile MD lb/inch Min.10 25 33 CD lb/inch Min. 8 15 20 Wet Tensile MD lb/inch Min. 5 9 13 CD lb/inch Min. 3 5 7.5 ____________________ 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.

"' '' ' ~.631g~

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 ~ ~3l!~1 -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.

~ ~ 63~9 ~ --(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 ~1~319~

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.

~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:

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.

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

Claims

1. A laminate comprising a wall or ceiling having a wall liner product adhered thereto, and an outer surface on the wall liner product which is suitable for the application of paint or decorative wall covering, the wall liner product comprising a wet-laid felt sheet having sufficient stiffness in the presence of moisture to cover imperfections in the underlyinq walls and ceilings.

2. The laminate of claim 1, further comprising a layer of paint on said outer surface.

3. The laminate of claim 1, further comprising a layer of adhesive on said outer surface and a decorative wall covering overlaying and adhered to said layer of adhesive.

4. The laminate of claim 1 wherein the wall liner has a wet MD Taber stiffness of at least about 20 and a wet CD Taber stiffness of at least about 14.

5. A wet-laid, composite, felt sheet product having a wet MD Taber stiffness of at least about 20 and a wet CD Taber stiffness of at least about 14.

6. The product of claim 5 having a layer of water resistant coating on each side thereof.

7. A wet-laid, composite, felt sheet product having a layer of water resistant coating on each side thereof and a wet MD Taber stiffness of at least about 6 and a wet CD Taber stiffness of at least about 2.

8. A laminate comprising a wall or ceiling having a wall liner product adhered thereto, and an outer surface on the wall liner product which is suitable for the application of paint or decorative wall covering, the wall liner product comprising a wet-laid felt sheet having and a wet MD Taber stiffness of at least about 6 and a wet CD Taber stiffness of at least about 2.

9. The laminate of claim 8, further comprising a layer of paint on said outer surface.

10. The laminate of claim 8, further comprising a layer of adhesive on said outer surface and a decorative wall covering overlaying and adhered to said layer of adhesive.

11. A furnish for preparing a wet-laid, composite, felt sheet product, the components of the furnish comprising from about 6 to about 30 percent of a water dispersible fiber, from about 50 to about 90 percent of an inorganic filler, from about 8 to about 20 percent of a binder and from about 0.1 to about 0.3 percent of a flocculant or flocculant and coagulant, wherein one or more of said components are selected to provide a wet MD Taber stiffness of at least about 20 and a wet CD Taber stiffness of at least about 14 in a felt sheet product having a caliper of about 15 mils.

12. The furnish of claim 11 wherein the binder is selected to provide the requisite stiffness.