ACOUSTICAL CEILING TILE

Abstract

An acoustical tile including: 8 to 25 wt % mineral wool, 9 to 15 wt % starch binder, 9 to 15 wt % cellulosic fiber, wherein preferably the cellulosic fiber is newsprint, and 40 to 65 wt % perlite, wherein the weight ratio of the starch to the cellulosic fiber is 0.6 to 1.3:1; and a process for making the acoustical tile.

Claims

1. An acoustical tile comprising: 8 to 25 wt % mineral wool, 9 to 15 wt % starch binder, 9 to 15 wt % cellulosic fiber, and 40 to 65 wt % perlite, wherein a weight ratio of the starch to the cellulosic fiber is 0.6 to 1.3:1.

2. The acoustical tile of claim 1, wherein the acoustical tile has: an absence of glass beads, an absence of clay, an absence of vermiculite, an absence of gypsum, an absence of calcium carbonate, an absence of magnesium carbonate, and an absence of Zinc pyrithione.

3. The acoustical tile of claim 1, wherein the cellulosic fiber comprises newsprint, wherein 0% of the cellulosic fiber is provided by paper sludge obtained from pulp and paper processing waste.

4. The acoustical tile of claim 1, wherein the acoustical tile has: an absence of glass beads, an absence of clay, an absence of vermiculite, an absence of gypsum, an absence of calcium carbonate, an absence of magnesium carbonate, an absence of Zinc pyrithione, an absence of inorganic material other than perlite and mineral wool, and 0% of the cellulosic fiber is provided by paper sludge obtained from pulp and paper processing waste.

5. The acoustical tile of claim 1, wherein the starch to cellulosic fiber weight ratio is 0.7 to 1.1:1.0.

6. The acoustical tile of claim 1, wherein the starch to cellulosic fiber weight ratio is 0.7 to 0.9:1.0 and the cellulosic fiber comprises newsprint.

7. The acoustical tile of claim 1, wherein the acoustical tile comprises: 8.0 to 20.0 wt % mineral wool, 9.5 to 13.0 wt % starch binder, 10.0 to 14.5 wt % cellulosic fiber, and 45.0 to 65.0 wt % perlite; wherein the starch:cellulosic fiber weight ratio is 0.7-1.1:1.0.

8. The acoustical tile of claim 1, wherein the acoustical tile comprises: 15.0 to 20.0 wt % mineral wool, 9.5 to 10.5 wt % starch binder 12.0 to 14.0 wt % cellulosic fiber, wherein said cellulosic fiber is newsprint, and 55.0 to 65.0 wt % perlite; wherein the starch:cellulosic fiber weight ratio is 0.7-0.9:1.0.

9. The acoustical tile of claim 1, wherein the acoustical tile is about 4/8 inches to about 1 inch thick.

10. The acoustical tile of claim 1, wherein the acoustical tile is about inches to about inches thick.

11. A process for manufacturing acoustical tile in a water-felting process, comprising: mixing an aqueous slurry comprising water and, ingredients comprising on a water free-basis: 8 to 25 wt % mineral wool, 9 to 15 wt % starch binder, 9 to 15 wt % cellulosic fiber, and 40 to 65 wt % perlite, wherein a weight ratio of the starch to the cellulosic fiber is 0.6 to 1.3:1.0; continuously flowing the slurry onto a moving foraminous support wire to form a cake; dewatering the cake to form a base mat such that the cake has a drain time of less than 20 seconds; and drying the base mat to produce the acoustical tile.

12. The process of claim 11, wherein the acoustical tile has: an absence of glass beads, an absence of clay, an absence of vermiculite, an absence of gypsum, an absence of calcium carbonate, an absence of magnesium carbonate, an absence of Zinc pyrithione.

13. The process of claim 11, wherein the cellulosic fiber comprises newsprint, wherein 0% of the cellulosic fiber is provided by paper sludge obtained from pulp and paper processing waste.

14. The process of claim 11, wherein the acoustical tile has: an absence of glass beads, an absence of clay, an absence of vermiculite, an absence of gypsum, an absence of calcium carbonate, an absence of magnesium carbonate, an absence of Zinc pyrithione, an absence of inorganic material other than perlite and mineral wool, and 0% of the cellulosic fiber is provided by paper sludge obtained from pulp and paper processing waste.

15. The process of claim 11, wherein the starch to cellulosic fiber weight ratio is 0.7 to 1.1:1.0.

16. The process of claim 11, wherein the starch to cellulosic fiber weight ratio is 0.7 to 0.9:1.0 and the cellulosic fiber comprises newsprint.

17. The process of claim 11, wherein the acoustical tile comprises: 8.0 to 20.0 wt % mineral wool, 9.5 to 13.0 wt % starch binder, 10.0 to 14.5 wt % cellulosic fiber, and 45.0 to 65.0 wt % perlite; wherein the starch:cellulosic fiber weight ratio is 0.7-1.1:1.0.

18. The process of claim 11, wherein the acoustical tile comprises: 15.0 to 20.0 wt % mineral wool, 9.5 to 10.5 wt % starch binder 12.0 to 14.0 wt % cellulosic fiber, wherein said cellulosic fiber is newsprint, and 55.0 to 65.0 wt % perlite; wherein the starch:cellulosic fiber weight ratio is 0.7-0.9:1.0.

19. The process of claim 11, wherein the acoustical tile is about 4/8 inches to about 1 inch thick.

20. The process of claim 11, wherein the acoustical tile is about inches to about inches thick.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0038] FIG. 1 shows an acoustical ceiling tile of the present invention.

[0039] FIG. 2 schematically shows a water felting line to perform the process for making acoustical tile of the present invention.

[0040] FIG. 3 shows a plot of 90 F./90% Relative Humidity (RH) Cutability Rating as a Function of Starch/Newsprint Ratio data from Example 1.

[0041] FIG. 3.1 shows a sample having a cutability rating of 1.

[0042] FIG. 3.2 shows a sample having a cutability rating of 2.

[0043] FIG. 3.3 shows a sample having a cutability rating of 3.

[0044] FIG. 3.4 shows a sample having a cutability rating of 4.

[0045] FIG. 3.5 shows a sample having a cutability rating of 5.

[0046] FIG. 4 shows a plot of 90 F./90% Relative Humidity Cutability Force as a Function of Percent Newsprint data from Example 1.

[0047] FIG. 5 shows a photograph of a first Board of composition 1 having Newsprint: 19.5%; Starch: 7.5% conditioned at 70 F./50% RH from Example 1.

[0048] FIG. 6 shows a photograph a second Board of composition 1 having Newsprint: 19.5%; Starch: 7.5% conditioned at 90 F./90% RH from Example 1.

[0049] FIG. 7 shows a photograph of a first Board of composition 6 having Newsprint: 10.0%; Starch: 10.0% conditioned at 70 F./50% RH from Example 1.

[0050] FIG. 8 shows a photograph of a second Board of composition 6 having Newsprint: 10.0%; Starch: 10.0% conditioned at 90 F./90% RH from Example 1.

[0051] FIG. 9 shows a photograph of a first Board of composition 10 having Newsprint: 10.0%; Starch: 12.5% conditioned at 70 F./50% RH from Example 1.

[0052] FIG. 10 shows a photograph of a second Board of composition 10 having Newsprint: 10.0%; Starch: 12.5% conditioned at 90 F./90% RH from Example 1.

[0053] FIG. 11 shows a plot of 70 F./50% RH Cutability Rating as a Function of Starch/Newsprint Ratio data from Example 2.

[0054] FIG. 12 shows a plot of 70 F./50% RH Cutability Force (lb-f) as a Function of Percent Starch data from Example 2.

[0055] FIG. 13 shows a plot of 90 F./90% RH Cutability Rating as a Function of Starch/Newsprint Ratio data from Example 2.

[0056] FIG. 14 shows a plot of 90 F./90% RH Cutability Force (lb-f) as a Function of Percent Newsprint data from Example 2.

[0057] FIG. 15 shows a photograph of Control Board having Newsprint: 19.5%; Starch: 7.5% conditioned at 70 F./50% RH from Example 2.

[0058] FIG. 16 shows a photograph of Trial Board 5 having Newsprint: 12.0%; Starch: 10.0% conditioned at 70 F./50% RH from Example 2.

[0059] FIG. 17 shows a photograph of Trial Board 1 (which is a second Control Board) having Newsprint: 18.0%; Starch: 8.0% conditioned at 90 F./90% RH from Example 2.

[0060] FIG. 18 shows a photograph of Trial Board 5 having Newsprint: 12.0%; Starch: 10.0% conditioned at 90 F./90% RH from Example 2.

[0061] FIG. 19 shows a photograph of Control Board having Newsprint: 20.0%; Starch: 8.0% conditioned at 70 F./50% RH from Example 3.

[0062] FIG. 20 shows a photograph of Trial Board 1 having Newsprint: 15.0%; Starch: 9.0% conditioned at 70 F./50% RH from Example 3.

[0063] FIG. 21 shows a photograph of Trial Board 2 having Newsprint: 12.0%; Starch: 10.0% conditioned at 70 F./50% RH from Example 3.

[0064] FIG. 22 shows a photograph of Control Board having Newsprint: 20.0%; Starch: 8.0% conditioned at 90 F./90% RH from Example 3.

[0065] FIG. 23 shows a photograph of Trial Board 1 having Newsprint: 15.0%; Starch: 9.0% conditioned at 90 F./90% RH from Example 3.

[0066] FIG. 24 shows a photograph of Trial Board 2 having Newsprint: 12.0%; Starch: 10.0% conditioned 90 F./90% RH at from Example 3.

[0067] FIG. 25 shows a photograph of First Production Line Control Board having 20.0% Newsprint/8.0% Starch conditioned at 70 F./50% RH of Example 4.

[0068] FIG. 26 shows a photograph of First Production Line Trial 1 Board having 12.0% Newsprint/10.0% Starch conditioned at 70 F./50% RH of Example 4.

[0069] FIG. 27 shows a photograph of First Production Line Control Board having 20.0% Newsprint/8.0% Starch conditioned at 90 F./90% RH of Example 4.

[0070] FIG. 28 shows a photograph of First Production Line Trial 1 Board having 12.0% Newsprint/10.0% Starch conditioned 90 F./90% RH at of Example 4.

[0071] FIG. 29 shows a photograph of Second Production Line Control Board having 20.0% Newsprint/8.0% Starch conditioned at 70 F./50% RH of Example 4.

[0072] FIG. 30 shows a photograph of Second Production Line Trial 1 Board having 15.0% Newsprint/9.0% Starch conditioned at 70 F./50% RH of Example 4.

[0073] FIG. 31 shows a photograph of Second Production Line Trial 2 Board having 12.0% Newsprint/10.0% Starch conditioned at 70 F./50% RH of Example 4.

[0074] FIG. 32 shows a photograph of Second Production Line Control Board having 20.0% Newsprint/8.0% Starch conditioned at 90 F./90% RH of Example 4.

[0075] FIG. 33 shows a photograph of Second Production Line Trial 1 Board having 15.0% Newsprint/9.0% Starch conditioned at 90 F./90% RH of Example 4.

[0076] FIG. 34 shows a photograph of Second Production Line Trial 2 Board having 12.0% Newsprint/10.0% Starch conditioned at 90 F./90% RH of Example 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0077] FIG. 1 shows an acoustical ceiling tile 10 of the present invention.

[0078] Ceiling tiles or panels are commonly used to construct a suspended ceiling. The tiles are laid in a rectangular grid and typically have nominal face dimensions of 22 and 24, or metric equivalents of these dimensions. A generally conventional wet felting process, known in the art, is used to produce a tile base mat in accordance with the present invention. In such a process, the base mat constituents are mixed in a water slurry which is deposited on a moving wire to form a layer of the mat material at some specified thickness. The material layer gravity drains and can be subsequently subjected to vacuum and pressing to draw off additional water content. Such vacuuming and pressing steps may be repeated. After this mechanical dewatering, the material can be conveyed to a dryer where remaining water is evaporated out of the mat and a binder in the mat formulation is optionally caused to set or cure.

[0079] The invention involves a discovery of a combination of starch binder and cellulose material in the form of newsprint, and their relative proportions in weight ratios of starch to newsprint, that produce a ceiling tile base mat with improved processing characteristics like ease of cutting and final tile appearance, in addition to acceptable material properties and performance characteristics.

[0080] The invention provides an acoustical tile comprising: [0081] 8.0 to 25.0 wt %, preferably 8.0 to 20.0 wt %, more preferably 15.0 to 20.0 wt % mineral wool, [0082] 9.0 to 15.0 wt %, preferably 9.5 to 13.0 wt %, more preferably 9.5 to 10.5 wt % starch binder, [0083] 9.0 to 15.0 wt %, preferably 10.0 to 14.5 wt %, more preferably 12.0 to 14.0 wt % cellulosic fiber, preferably the cellulosic fiber is newsprint, and [0084] 40.0 to 65.0 wt %, preferably 45.0 to 65.0 wt %, more preferably 55.0 to 65.0 wt % perlite; [0085] wherein the weight ratio of the starch to the cellulosic fiber is 0.6 to 1.3:1.0, preferably 0.7 to 1.0:1.0, more preferably 0.7 to 0.9:1.0, most preferably 0.7 to 0.8:1.0.

[0086] The invention provides a process for manufacturing the acoustical tile in a water-felting process, the process comprising:

[0087] mixing an aqueous slurry comprising water and, ingredients comprising on a water free-basis: [0088] 8.0 to 25.0 wt %, preferably 8.0 to 20.0 wt %, more preferably 15.0 to 20.0 wt % mineral wool, [0089] 9.0 to 15.0 wt %, preferably 9.5 to 13.0 wt %, more preferably 9.5 to 10.5 wt % starch binder, [0090] 9.0 to 15.0 wt %, preferably 10.0 to 14.5 wt %, more preferably 12.0 to 14.0 wt % cellulosic fiber, preferably the cellulosic fiber of any of these three ranges is newsprint, and [0091] 40.0 to 65.0 wt %, preferably 45.0 to 65.0 wt %, more preferably 55.0 to 65.0 wt % perlite; [0092] wherein the weight ratio of the starch to the cellulosic fiber is 0.6 to 1.3:1.0, preferably 0.7 to 1.0:1.0, more preferably 0.7 to 0.9:1.0, most preferably 0.7 to 0.8:1;

[0093] continuously flowing the slurry onto a moving foraminous support wire to form a cake;

[0094] dewatering the cake to form a base mat; and

[0095] drying the base mat to produce the acoustical tile.

[0096] FIG. 2 schematically shows a water felting line to make the acoustical tile of the present invention. As shown in FIG. 2, in the process, the aqueous slurry 22 of the composition is flowed from an agitated holding tank 20 onto a moving foraminous support wire 30 where it forms the cake 40 which is dewatered, first by gravity in gravity dewatering unit 50 and then by vacuum in vacuum dewatering unit 60. The dewatered cake 70 is then pressed in a pressing unit 80 to a selected thickness to form the base mat 90. The pressing step further dewaters the base mat 90. The base mat 90 is then passed into a drying kiln 100 in which the moisture in the base mat is reduced to less than 5 wt. % and preferably less than 1 wt. %. It is then cut by a blade 110 to form cut sheets 120 for acoustical tile.

[0097] The water felted base mat acoustical tile described herein after being dried is typically top coated with a paint-like coating to improve its light reflectance and appearance as a finished panel or tile as is customary in the industry. Before top coating, the acoustical tile can be ground to produce a relatively smooth surface. Additionally, the face of the acoustical tile can be perforated and fissured to improve its sound absorption performance.

[0098] The acoustical tile of the invention, as well as the acoustical tile and the slurry in the process for making the acoustical tile of the invention, preferably has an absence of glass beads.

[0099] The acoustical tile of the invention, as well as the acoustical tile and the slurry in the process for making the acoustical tile of the invention, preferably has an absence of clay.

[0100] The acoustical tile of the invention, as well as the acoustical tile and the slurry in the process for making the acoustical tile of the invention, preferably has an absence of vermiculite.

[0101] The acoustical tile of the invention, as well as the acoustical tile and the slurry in the process for making the acoustical tile of the invention, preferably has an absence of gypsum.

[0102] The acoustical tile of the invention, as well as the acoustical tile and the slurry in the process for making the acoustical tile of the invention, preferably has an absence of calcium carbonate.

[0103] The acoustical tile of the invention, as well as the acoustical tile, as well as the slurry in the process for making the acoustical tile of the invention, preferably has an absence of magnesium carbonate.

[0104] The acoustical tile of the invention, as well as the acoustical tile and the slurry in the process for making the acoustical tile of the invention, preferably has an absence of zinc pyrithione.

[0105] Preferably the acoustical tile of the invention, as well as the acoustical tile and the slurry in the process for making the acoustical tile of the invention, has an absence of all the following ingredients: glass beads, clay, vermiculite, gypsum, calcium carbonate, and magnesium carbonate.

[0106] Preferably the acoustical tile of the invention, as well as the acoustical tile and the slurry of the process for making the acoustical tile of the invention, on a water free basis, has an absence of inorganic material other than perlite and mineral wool. This exclusion is on a water free basis so it does not exclude water.

[0107] TABLE 1, lists compositions of the acoustical tile of the invention, as well as the acoustical tile and the slurry of the process for making the acoustical tile of the invention. Each Preferred range or More Preferred range is individually a preferred range or more preferred range for the invention. Thus, preferably any Preferred range can be independently substituted for a corresponding Useable range. Likewise, more preferably any More Preferred range can be independently substituted for a corresponding Useable range or a corresponding Preferred range.

TABLE-US-00001 TABLE 1 Compositions (weight percents on a water free basis) Component Useable Preferred Most Preferred Mineral Wool (wt. %) 8 to 25 8 to 20 15 to 20 Binder (starch) (wt. %) 9 to 15 9.5 to 13 9.5 to 10.5 Cellulosic fiber (preferably 9 to 15 10 to 14.5 12 to 14 newsprint) (wt. %) perlite (wt. %) 40 to 65 45 to 65 55 to 65 Weight Ratio of Starch to 0.6 to 1.3:1 0.7-1.1:1 0.7 to 0.9:1 Cellulosic fiber

[0108] The proportions of the ingredients for a product, or used in a process, of the present invention fall within the ranges specified in TABLE 1. Variation in the proportions of ingredients can be made within the broader ranges of starch and newsprint, without a significant loss of performance. Cornstarch is the preferred binder. A practical acoustical tile of the invention preferably has a nominal thickness t (FIG. 1) of about 4/8 inches to 1 inch thick, more preferably about to inch. Also, a practical acoustical tile of the invention has a density of about 10 to 17 pounds/cubic foot.

[0109] The combination of starch and newsprint fiber in the specified weight ratios of TABLE 1, improves the hardness of the final tile. This hardness of the tile allows for improved ease of cutting with better cut appearance and reduces cutting force when handling the dried mat tile under humid conditions. This reduces scrap and the time to cut the tile to make the product.

[0110] Mineral Wool

[0111] The disclosed acoustical tile/panel compositions also contain mineral wool of the type conventionally used in acoustical tiles. Mineral wool in a ceiling tile increases the sound absorption (NRC) of the tile. In general, the higher the amount of mineral wool the better the sound absorption. Mineral wool also advantageously gives bulking to the slurry during formation of the core. The mineral wool may be any of the conventional mineral fibers prepared by attenuating a molten stream of basalt, slag, granite or other vitreous mineral constituent. The molten mineral is either drawn linearly through orifices, commonly referred to as textile fiber, or it is recovered tangentially off the face of a spinning cup or rotor, commonly referred to as wool fiber. The mineral wool constituent is present in an amount ranging from 8.0 to 25.0 wt %, more preferably 8.0 to 20.0 wt %, most preferably 15.0 to 20.0 wt %.

[0112] Binder

[0113] The binder comprises starch and mixtures thereof.

[0114] Starch is the preferred binder and may or may not be cooked prior to use. A starch gel may be prepared by dispersing starch particles in water and heating the slurry until the starch is fully or partially cooked and the slurry thickens to a viscous gel. However, if conventional hydropulped fibers are used as a supplemental source of fiber, they may be incorporated into the starch slurry prior to cooking. The cooking temperature of the starch slurry should be closely monitored to assure the desired degree of swelling of the starch granules. The cooking temperature for cornstarch can range from about 160 F. (71 C.) to about 195 F. (90 C.). Starch may also be used as a binder without pre-cooking the starch, because it forms a gel during the process of drying the base mat. Cornstarch is the preferred binder. Preferably the binder is solely cornstarch. Preferably the binder has an absence of latex. Preferably the binder has an absence of polyamine epichlorohydrin resins.

[0115] Increased binder content, in the form of starch, can be used to increase strength (MOR-modulus of rupture (psi)) and hardness and enhance the cutability of the finished tiles/panels. The binder is present from 9.0 to 15.0 wt %, preferably from 9.5 to 13.0 wt %, more preferably from 9.5 to 10.5 wt % in the product and process of the present invention.

[0116] Cellulosic Fibers

[0117] A major component in the acoustical tile compositions of this invention is the cellulosic fiber, which serves to provide both wet strength (i.e., the strength of the wet mat prior to drying). The cellulose fiber may also function as a binder and may help to retain fines. Preferably the cellulosic fiber is newsprint (also known as (news). It is well known to use newsprint in acoustical tile formulations. In acoustical tile formulations of the present invention, hydro-pulped newsprint is preferred. Refined paper fibers and wood fiber may also be used as the source of the cellulosic fiber, however, it has been found ceiling tiles made with wood fiber, either softwood or hardwood, are more difficult to cut with a knife at the installation site. Furthermore, wood fibers are a more expensive source of the cellulosic fiber. The cellulosic fiber is present from 9.0 to 15.0 wt %, preferably from 10.0 to 14.5 wt %, more preferably from 12.0 to 14.5 wt %, most preferably from 12.0 to 14.0 wt % in the product and process of the present invention.

[0118] The acoustical tile of the invention, as well as the acoustical tile and the slurry of the process for making the acoustical tile of the invention, preferably has 0% of the cellulosic fiber provided by paper sludge obtained from pulp and paper processing waste.

[0119] Perlite

[0120] An ingredient of the disclosed acoustical tile compositions is a perlite. Expanded perlite is preferred for its low cost and performance. The expanded perlite provides porosity and loft in the final product, which enhances acoustical properties.

[0121] Perlite is a form of glassy rock, similar to obsidian with the capacity to expand greatly on heating. Perlite generally contains 65-75 wt % SiO.sub.2, 10-20 wt % Al.sub.2O.sub.3, 2-5 wt % H.sub.2O, and smaller amounts of sodium, potassium, iron and calcium oxides. Expanded perlite denotes any glass rock and more particularly a volcanic glass that has been expanded suddenly or popped while being heated rapidly. This popping generally occurs when the grains of crushed perlite are heated to the temperatures of incipient fusion. The water contained in the particles is converted into steam and the crushed particles expand to form light, fluffy, cellular particles. Volume increases of the particles of at least ten fold are common. Expanded perlite is generally characterized by a system of concentric, spheroidal cracks, which are called perlite structure. Different types of perlite are characterized by variations in the composition of the glass affecting properties such as softening point, type and degree of expansion, size of the bubbles and wall thickness between them, and porosity of the product.

[0122] In the conventional process of preparing expanded perlite, the perlite ore is first ground to a fine size. The perlite is expanded by introducing the finely ground perlite ore into the heated air of a perlite expander. Typically the expander heats the air to about 1750 F. The finely ground perlite is carried by the heated air which heats the perlite and causes it to pop like popcorn to form the expanded perlite having a density of about 3 to 10 pounds per cubic foot. When expanded perlite is placed in contact with water, the water penetrates the cracks and fissures and enters into the air filled cavities of the perlite, thereby causing the perlite to retain large amounts of water within the expanded perlite particles.

[0123] Using the relatively high density perlite, i.e., a perlite which has been expanded to a density of over 7 or 8 pounds per cubic foot (versus the normal range of 3 to 5 pounds per cubic foot), lowers the water needed to form a suitable slurry. See, U.S. Pat. No. 5,911,818 to Baig. The aqueous slurry with less water requires less dewatering, and produces a base mat having less water retained by the perlite. The resulting product has improved compressive resistance and maintained fire ratings, as defined by ASTM Test No. E119. The base mat having a lower water content can be dried faster which allows the entire water felting line to be run at higher speed.

[0124] High density perlite is also beneficial when manufacturing fire rated ceiling tiles which must meet a minimum density. However, when the density of the expanded perlite exceeds about 20 pounds per cubic foot, the perlite does not produce as much loft or bulk in the final product. As a result, the density of the final product may be too high to maintain the low thermal conductivity required to pass the ASTM E119 fire endurance test.

[0125] The disclosed ceiling tile compositions contain from 40.0 to 65.0 wt % perlite of either the high or low density type, preferably 45.0 to 65.0 wt %, more preferably 55.0 to 65.0 wt %.

[0126] Prior to use in the sound-absorbing filler, the expanded perlite is optionally at least partially coated with a coating. Preferred coatings include silicon coatings and polymeric coatings. The coatings are applied to the expanded perlite using any practical coating method. Spraying is the preferred method of applying the coating. While not wishing to be bound by theory, it is believed the coating limits water absorption by reducing the amount of water that enters the interior of the aggregate particles. When less water is absorbed, less energy is required to drive off this excess water, reducing the kiln temperature or the residence time of the product in the kiln.

[0127] Inorganic Materials

[0128] Commercial clays include kaolin, bentonite, and other clays known to those skilled in the art of ceiling tile fabrication can be added to mixtures for acoustical tiles of the present invention. Addition of these ingredients is optional and not preferred. Preferably there is an absence of these ingredients.

[0129] Calcium carbonate (CaCO.sub.3) is a typical material that has no significant value in the board properties except it may give some hardness to the product and it can lower the cost of the product. Addition of this ingredient is optional and not preferred. Preferably there is an absence of this ingredient.

[0130] Other commonly used low cost inorganic materials are gypsum and fly ash. The gypsum may be of any form. Typical forms are calcium sulfate dihydrite, CaSO.sub.4.2H.sub.2O (which can be in the form of re-hydrated hemihydrate, for example); calcium sulfate hemihydrate, CaSO.sub.4.H.sub.2O; or calcium sulfate anhydrite, CaSO.sub.4. Gypsum has limited solubility in water and acts as a flocculent. By functioning as a flocculent in the slurry, the gypsum helps to retain and uniformly distribute the fine particles (inorganic clay, organic starch, short cellulosic fibers, etc.) in the mat during the processing (dewatering, vacuum and wet pressing).

[0131] Gypsum may be present from 0 to 30.0 wt %. However, addition of this ingredient is optional and not preferred. Preferably there is an absence of this ingredient.

[0132] Fly ash may be present from 0 to 30.0 wt %. However, addition of this ingredient is optional and not preferred. Preferably there is an absence of this ingredient.

[0133] Optional Additional Ingredients

[0134] An optional facing material is a scrim layer. It is positioned, for example, on the front face of the base mat of the acoustical panel. A scrim layer is also useful on the back face of the base mat (core) of the acoustical panel. Preferably, the scrim layer is porous to facilitate attachment to the base mat and is acoustically transparent. Any material that has these properties is useful as scrim material. Some examples of suitable scrims include non-woven fiberglass scrims, woven fiberglass mats, other synthetic fiber mats such as polyester and combinations thereof.

[0135] The invention can have an absence of any of these optional elements.

[0136] The following specific examples further illustrate embodiments of the invention. Unless specified to the contrary, all amounts are expressed as parts by weight on a dry solids total weight basis. Also, unless specified to the contrary, all amounts are expressed as percent are in weight percent. These examples are for illustration only and are not to be construed as limitations on this disclosure.

EXAMPLES

Example 1

[0137] The present report presents the results of a lab board series in which the percentages of starch and newsprint were systematically varied (see TABLE 2 for formulation and preparation details and cutability; see TABLE 3 for board properties) to determine the effect of these variables on board properties including cutability under high humidity conditions. This example studied whether, it was possible to achieve a harder core that exhibits improved cutability under high humidity conditions by varying the ratio and total amount of starch and newsprint.

TABLE-US-00002 TABLE 2 Board composition and preparation details Average Average News Cutability Cutability Board (grams) Rating Rating Comp. News (2.4% Starch Starch Clay Clay Water 70 F./ 90 F./ No. (%) solids) (%) (grams) (%) (gms) (lbs) 50% RH 90% RH 1 19.5 3674 7.5 33.6 4.0 17.94 13.07 3.7 5.0 2 17.0 3203 7.5 33.6 6.5 29.15 14.09 3.5 4.9 3 14.5 2732 7.5 33.6 9.0 40.36 15.10 3.8 4.8 4 12.0 2261 7.5 33.6 11.5 51.57 16.11 3.8 4.0 5 9.5 1790 7.5 33.6 14.0 62.78 17.13 3.8 4.0 6 10.0 1884 10.0 44.8 11.0 49.33 16.93 1.4 2.9 7 12.0 2261 10.0 44.8 9.0 40.36 16.11 2.4 2.9 8 14.5 2732 10.0 44.8 6.5 29.15 15.10 1.7 3.0 9 17.0 3203 10.0 44.8 4.0 17.94 14.09 2.2 3.4 10 10.0 1884 12.5 56.0 8.5 38.12 16.93 1.0 1.2 11 12.0 2261 12.5 56.0 6.5 29.15 16.11 1.0 2.9 12 14.5 2732 12.5 56.0 4.0 17.94 15.10 1.0 2.9 13 17.0 3203 12.5 56.0 1.5 6.73 14.09 1.0 3.1

TABLE-US-00003 TABLE 3 Board Properties Board Target Thickness 0.600 (inches) Board Target Density 13.0 (pounds per cubic foot) Stock Consistency 4.5% solids in a slurry wherein the remainder is water Cationic polyacrylamide 0.08% or 179.7 grams of 0.2% flocculent flocculent solution per lab board

[0138] A series of 26 lab scale boards were produced using the compositions presented in TABLE 2 (two boards of each of the thirteen compositions) and using the standard lab board preparation method as follows.

[0139] Lab Board Making Procedure:

[0140] Weigh out water and place in mix bucket.

[0141] Add paper fiber, mineral wool, clay and perlite in a bucket with appropriate mixing. Add flocculent at end of mixing cycle.

[0142] Place nonwoven scrim on wire in lab scale forming box and fill the box to a level that covers the scrim.

[0143] Add slurry to lab scale forming box. Open bottom valve and allow slurry to drain to form a felted mat.

[0144] Apply to the felted mat vacuum, pressing and then additional vacuum to remove excess water.

[0145] Then weigh the formed mat.

[0146] Transfer to oven. All boards were dried at 600 F. with steam to fully cook the starch within the formed base mat followed by drying without steam at 300 F. to constant weight.

[0147] The dry boards were conditioned for 24 hours at 70 F./50% RH prior to physical testing using established lab physical test methods. For cutability testing, the boards were conditioned at either 70 F./50% RH or 90 F./90% RH using a spacing rack for 3 days prior to testing.

[0148] The boards were tested for cutability. The boards were also tested for the Physical Test Results of Modulus of Rupture (MOR)(psi), Corrected MOR (CMOR)(psi), MOE (psi), and 2 inch Ball Hardness (lb-f), using modified test methods as presented in ASTM C367. The modifications relative to the stated ASTM C367 requirements are relatively minor and would not substantively affect the results or conclusions (see below).

[0149] For MOR the tests conformed to the basic testing parameters of this standard; although the tests utilized a shorter span than what is specified in ASTM C367 (i.e., 8 versus the specified 10). This change should not make a material difference in the test results.

[0150] Corrected MOR is a calculated value not subject to ASTM C367.

[0151] For Hardness the tests conformed to the basic testing parameters of this standard; although the tests did not routinely condition the samples under 70/50 conditions prior to testing as required by the standard.

[0152] Loss on Ignition (LOI)(%) was measured after heating the sample to 1000 F. (538 C.) for about 30 minutes.

[0153] MOE refers to Modulus of Elasticity and is a measure of the relative stiffness of the test sample. A sample with a higher MOE value will deflect less under a given load. The units for MOE are psi.

[0154] Cutabilitv Test Results

[0155] The results of cutability testing are presented in TABLE 2, FIG. 3, and FIG. 4. The data shows in terms of the cutability rating (i.e., the cleanness of the cut), the ratio of starch to newsprint was the controlling factor. By adjusting this ratio and keeping the mineral wool and perlite percentages relatively constant it was possible to achieve a cutability rating of near 1 even when tested at 90 F./90% RH conditions (see cutability photographs of FIGS. 5-10).

[0156] FIG. 3 shows a plot of 90 F./90% Relative Humidity Cutability Rating as a Function of Starch/Newsprint Ratio data from Example 1. Each rating of the cutability Rating System has a number from 1 to 5. 1=perfect, 2=good, 3=fair, 4=poor, and 5=unacceptable (judged by smoothness of cuts). A rating of perfect denoted a completely smooth cut upon drawing a utility knife through the full thickness of the panel. An unacceptable rating denoted a very ragged edge that is aesthetically objectionable. The rating of an individual tile is highly dependent on the humidity to which the tile has been subjected.

[0157] Although not necessarily from this Example, FIGS. 3.1-3.5 show examples of these cutability ratings. FIG. 3.1 shows a sample having a cutability rating of 1. FIG. 3.2 shows a sample having a cutability rating of 2. FIG. 3.3 shows a sample having a cutability rating of 3. FIG. 3.4 shows a sample having a cutability rating of 4. FIG. 3.5 shows a sample having a cutability rating of 5.

[0158] FIG. 4 shows a plot of 90 F./90% Relative Humidity Cutability Force as a Function of Percent Newsprint data from Example 1. In the cutability force test, a clean new razor blade is pulled through the full thickness of a 3 wide sample of ceiling tile. The blade is included in part of a device that draws the blade through the sample at a set speed and angle and also contains a load cell to measure force required to do so. Load (maximum pounds force) is recorded. The blade used in the cutability and cutability force tests was a STANLEY 1992 utility blade (Stanley item number 11-921B). A new blade is installed after every cut.

[0159] FIG. 5 shows a photograph of a first Board of composition 1 having Newsprint: 19.5%; Starch: 7.5% conditioned at 70 F./50% RH.

[0160] FIG. 6 shows a photograph a second Board of composition 1 having Newsprint: 19.5%; Starch: 7.5% conditioned at 90 F./90% RH.

[0161] FIG. 7 shows a photograph of a first Board of composition 6 having Newsprint: 10.0%; Starch: 10.0% conditioned at 70 F./50% RH.

[0162] FIG. 8 shows a photograph of a second Board of composition 6 having Newsprint: 10.0%; Starch: 10.0% conditioned at 90 F./90% RH.

[0163] FIG. 9 shows a photograph of a first Board of composition 10 having Newsprint: 10.0%; Starch: 12.5% conditioned at 70 F./50% RH.

[0164] FIG. 10 shows a photograph of a second Board of composition 10 having Newsprint: 10.0%; Starch: 12.5% conditioned at 90 F./90% RH.

[0165] In terms of the cutability force (i.e., the force required to draw the knife through the panel), the percentage of newsprint appears to be the controlling factor. Minimizing the percentage of newsprint provides the smoothest and the easiest cut.

[0166] TABLE 4 summarizes the Cutability Test Results and Physical Test Results of Modulus of Rupture (MOR) (psi), Corrected MOR (CMOR)(psi), MOE (psi), 2 inch Ball Hardness (lb-f), and MOE for boards of selected compositions.

TABLE-US-00004 TABLE 4 90 F./90% Board 2 inch Ball RH Composition Newsprint Starch MOR Corrected Hardness Cutability No. (wt. %) (wt. %) (psi) MOR (psi) MOE (lb-f) Rating 1 19.5 7.5 130.99 129.57 16564 143.2 5.0 6 10.0 10.0 131.75 128.38 21519 143.7 2.9 10 10.0 12.5 149.32 149.14 22882 155.1 1.2

[0167] The above-described data shows the ratio of starch to newsprint appeared to be the controlling factor toward improving cutability. This data indicates by adjusting this ratio and keeping the mineral wool and perlite percentages relatively constant it is possible to achieve a cutability rating of near 1 when tested under 90 F./90% RH conditions.

[0168] The physical testing results indicate it should be possible to significantly reduce the level of paper fiber while only modestly increasing the level of starch and still maintain the current level of physical properties. For example, the MOR and Corrected MOR increase with less newsprint and more starch.

Example 2

[0169] Example 2 presents the results of a plant trial on a first commercial size production line in which the percentages of starch and newsprint were systematically varied (see TABLE 5 for formulation and trial details) to determine the effect of these variables on board properties including cutability under high humidity conditions. The plant trial included running five 2-hour trials using the following progression in base mat formula: Control 1 was performed first, then Trials 1-5 in order respectively, and lastly Control B.

TABLE-US-00005 TABLE 5 Trial Formulations (amounts in wt. % unless otherwise indicated; amounts total 100%) Starch Newsprint Wool Perlite Clay Starch:Newsprint Sample wt. % wt. % wt. % wt. % wt. % Weight Ratio Control 7.5 19.5 14.4 56.6 2.0 0.38:1 A Trial 1 8.0 18.0 14.6 57.4 2.0 0.44:1 Trial 2 8.5 16.5 14.8 58.2 2.0 0.52:1 Trial 3 9.0 15.0 15.0 59.0 2.0 0.60:1 Trial 4 9.5 13.5 15.2 59.8 2.0 0.70:1 Trial 5 10.0 12.0 15.4 60.6 2.0 0.83:1 Control 7.5 19.5 14.4 56.6 2.0 0.38:1 B

[0170] Cutability Test Results

[0171] TABLE 6 presents the results of cutability rating testing. In terms of the cutability rating (i.e., the cleanness of the cut) and cutability force, the ratio of starch to newsprint was the controlling factor when the samples were tested after 70 F./50% RH conditioning (see TABLE 6 and FIGS. 11-14). The blade used for the cutting tests is a typical utility knife blade. This example employed STANLEY 1992 Blades (11-921B).

TABLE-US-00006 TABLE 6 Results of cutability rating testing (each listed cutability value is an average of five measurements) Average Average Average Peak Average Peak Cutability Cutability Cutability Cutability Rating Rating Force (lb-f) Force (lb-f) Newsprint Starch 70 F./ 90 F./ 70 F./50% 90 F./90% Sample (wt. %) (wt. %) 50% RH 90% RH RH RH Control A 19.5 7.5 3.9 4.6 18.4 21.0 Trial 1 17.0 8.0 3.8 4.4 16.7 18.2 Trial 2 14.5 8.5 3.8 4.4 17.6 19.4 Trial 3 12.0 9.0 3.0 4.3 18.3 18.0 Trial 4 9.5 9.5 2.4 4.4 15.4 17.4 Trial 5 10.0 10.0 1.3 3.4 12.7 13.6

[0172] FIG. 15 shows a photograph of Control Board having Newsprint: 19.5%; Starch: 7.5% conditioned at 70 F./50% RH.

[0173] FIG. 16 shows a photograph of Trial Board 5 having Newsprint: 12.0%; Starch: 10.0% conditioned at 70 F./50% RH.

[0174] FIG. 17 shows a photograph of Trial Board 1 (a second Control Board) having Newsprint: 18.0%; Starch: 8.0% conditioned at 90 F./90% RH.

[0175] FIG. 18 shows a photograph of Trial Board 5 having Newsprint: 12.0%; Starch: 10.0% conditioned at 90 F./90% RH.

[0176] When the same samples were tested after 90 F./90% RH conditioning, increasing the starch/newsprint ratio affected a significant improvement in cutability rating. Trial 5 boards achieved the best cutability rating. However, even the Trial 5 boards did not achieve a cutability rating of near 1 (see FIGS. 11-14 as well as the cutability photographs of FIGS. 15-18 comparing Control Boards to Trial 5 Boards).

[0177] Possible reasons for the 90 F./90% RH cutability results differing compared to the Example 1 lab board results might include the following: 1) Possible high newsprint consistencies resulting in a higher level of newsprint in the final furnish than was shown on the computer; or 2) Possible incomplete cooking of the starch in the dryer. The lab boards were thoroughly steamed to ensure complete cooking of the starch. However, it is possible the selected trial boards were not completely cooked or came from a deck in the dryer with lower temperatures.

[0178] In terms of the cutability force values (i.e., the force necessary to draw the test knife blade through the sample), the data again showed the ratio of starch to newsprint appeared to be the controlling factor when the samples were tested after 70 F./50% RH conditioning. When the same samples were tested after 90 F./90% RH conditioning, the ratio of starch to newsprint appeared to again be the controlling factor. This data confirmed a higher starch/newsprint ratio contributed to significant improvements in cutability.

Example 3

[0179] Example 3 presents the results of another plant trial on a second commercial size production line in which the percentages of starch and newsprint were systematically varied under two trial scenarios (see TABLE 7 for formulation and trial details) to determine the effect of these variables on board properties including cutability under high humidity conditions. The plant trial was conducted on the first commercial size production line of Example 2. The trial included of running two 2-hour trials using the following progression in base mat formula: Control 1 was performed first, then Trial 1, and then Trial 2. Compared to the 2% clay of Example 2, the clay level of Example 3 was 0%. This applied to both the Control board as well as the Trial 1 and Trial 2 boards.

TABLE-US-00007 TABLE 7 Trial Formulations (amounts in wt. % unless otherwise indicated; amounts total 100%) Starch:Newsprint Trial Starch Newsprint Wool Perlite Clay Wt. Ratio Control 8.0 20.0 20.0 52.0 0 0.40:1 1 9.0 15.0 17.0 59.0 0 0.60:1 2 10.0 12.0 17.4 60.6 0 0.83:1

[0180] Cutability Test Results

[0181] The results of cutability testing are summarized in TABLE 8. Each cutability value is the averages of 8 individual samples with each sample cut in the machine direction.

[0182] The blade used for the cutting tests is a typical utility knife blade in the case of the present specification STANLEY 1992 Blades (11-921B).

TABLE-US-00008 TABLE 8 Summary of Cutability Test Results Average Average Average Peak Average Peak Cutability Cutability Cutability Cutability Rating Rating Force (lb-f) Force (lb-f) Starch Newsprint 70 F./ 90 F./ 70 F./50% 90 F./90% Sample (wt %) (wt %) 50% RH 90% RH RH RH Control 8.0 20.0 2.59 3.98 15.62 18.47 Trial 1 9.0 15.0 2.26 4.04 12.64 13.91 Trial 2 10.0 12.0 1.00 1.68 12.73 12.07

[0183] In terms of the cutability rating (i.e., the cleanness of the cut), the Trial 1 boards were roughly equal to the control boards while the Trial 2 boards were near perfect under 70 F./50% RH conditioning and significantly improved under 90 F./90% RH conditioning. This is further illustrated in the cutability photographs included in FIGS. 19-24.

[0184] FIG. 19 shows a photograph of Control Board having Newsprint: 20.0%; Starch: 8.0% conditioned at 70 F./50% RH from Example 3.

[0185] FIG. 20 shows a photograph of Trial Board 1 having Newsprint: 15.0%; Starch: 9.0% conditioned at 70 F./50% RH from Example 3.

[0186] FIG. 21 shows a photograph of Trial Board 2 having Newsprint: 12.0%; Starch: 10.0% conditioned at 70 F./50% RH from Example 3.

[0187] FIG. 22 shows a photograph of Control Board having Newsprint: 20.0%; Starch: 8.0% conditioned at 90 F./90% RH from Example 3.

[0188] FIG. 23 shows a photograph of Trial Board 1 having Newsprint: 15.0%; Starch: 9.0% conditioned at 90 F./90% RH from Example 3.

[0189] FIG. 24 shows a photograph of Trial Board 2 having Newsprint: 12.0%; Starch: 10.0% conditioned at 90 F./90% RH from Example 3.

[0190] This data from a plant trial conducted on the second commercial size production line confirmed a higher starch/newsprint ratio contributed to significant improvements in cutability.

Example 4

[0191] The present Example details the results of trials conducted on both the first commercial size plant production line of Example 2 and the second commercial size plant production line of Example 3 in which the starch/newsprint ratio was varied to verify its effect on cutability.

[0192] Specific observations from the trials and subsequent testing include the following:

[0193] First commercial size plant production line: The flexural strength results for the first commercial size production line trial showed a lower flexural strength in the machine direction for the trial boards compared to the control boards (90.3 psi versus 97.0 psi, respectively). The flexural strength results in the cross-machine direction were statistically equivalent.

[0194] Second commercial size plant production line: The flexural strength results for the production line trial were statistically equivalent for the Control, Trial 1 and Trial 2 boards.

[0195] The stiffness results for the First commercial size plant production line trial boards exhibited significantly lower MOE values in both the machine and cross-machine directions compared to the control boards. The stiffness results for the second commercial size production line trials exhibited significantly higher MOE values in both the machine and cross-machine directions for both trials compared to the control boards.

[0196] The 2 ball hardness results for the first commercial size production line trial material exhibited significantly lower hardness values compared to the control values. This may in part be due to the lower density for these trial boards. The 2 ball hardness results for the second commercial size production line trial exhibited higher hardness values for both trials compared to the control boards. Boards from both trials on the second commercial size production line were slightly higher in density than the control boards.

[0197] TABLE 9 shows average composition and physical properties of the boards manufactured on the first commercial size production line. TABLE 10 shows average composition and physical properties of the boards manufactured on the second production line.

[0198] TABLE 9 shows First Commercial Size Plant Production Line Trial Board Physical Properties (CIC Values). In TABLE 9 the Control values were averages of measurements from four boards produced 15 minutes apart on the line. The Trial values were averages of measurements from four boards produced 15 minutes apart on the line.

TABLE-US-00009 TABLE 9 Averaged Results Starch/ News- News Trial print Starch Wt. Thickness Density Corrected 2 Ball No. (wt. %) (wt. %) Ratio (inches) (lbs./ft.sup.3) MOR MOR MOE Hardness All 20.0 8.0 0.40 0.563 14.75 88.1 90.9 16465 129.9 Control Boards All Trial 12.0 10.0 0.83 0.561 13.36 68.4 86.0 11688 115.9 Boards

[0199] TABLE 10 shows Second Commercial Size Plant Production Line Trial Board Physical Properties (CIC Values). In TABLE 10 the Control values were averages of measurements from four boards produced 15 minutes apart on the line. Trial 1 values were averages of measurements from three boards produced 15 minutes apart on the line. Trial 2 values were averages of measurements from four boards produced 15 minutes apart on the line.

TABLE-US-00010 TABLE 10 News- Starch/ Trial print Starch News Wt. Thickness Density Corrected 2 Ball No. (wt. %) (wt. %) Ratio (inches) (lbs/ft.3) MOR MOR MOE Hardness All 20.0 8.0 0.40 0.557 14.09 89.1 89.2 17451 149.6 Control Boards All Trial 1 15.0 9.0 0.60 0.556 14.66 95.8 88.7 18930 164.1 Boards All Trial 2 12.0 10.0 0.83 0.556 14.30 93.4 90.9 19502 171.3 Boards

[0200] Cutability Test Results

[0201] The results of cutability testing are presented in the photographs of FIGS. 25-34 and summarized in TABLE 11 and TABLE 12. Each cutability value in TABLE 11 and TABLE 12 is the averages of 8 individual samples with each sample cut in the machine direction.

[0202] FIG. 25 shows a Cutability photograph of a First Commercial Size Plant Production Line Control Board having 20.0% News/8.0% Starch conditioned at 70 F./50% RH.

[0203] FIG. 26 shows a Cutability photograph of a First Commercial Size Plant Production Line Trial 1 Board having 12.0% News/10.0% Starch conditioned at 70 F./50% RH.

[0204] FIG. 27 shows a Cutability photograph of a First Commercial Size Plant Production Line Control Board having 20.0% News/8.0% Starch conditioned at 90 F./90% RH.

[0205] FIG. 28 shows a Cutability photograph of a First Commercial Size Plant Production Line Trial 1 Board having 12.0% News/10.0% Starch conditioned at 90 F./90% RH.

[0206] TABLE 11 summarizes First Plant Production Line Board Cutability Test Results. In TABLE 11 control values are averages of measurements from four boards produced 15 minutes apart on the line. Trial values are averages of measurements from four boards produced 15 minutes apart on the line. Each cutability value is the average of 8 individual samples from each board with each sample cut in the machine direction. To do the cutting the tests employed an INSTRON Test Machine with custom cutting jig employing the STANLEY cutting knife blade mentioned above.

TABLE-US-00011 TABLE 11 Summary of Cutability Test Results Time after Cutability Force start of Cutability Rating 90 F./ test LOI 70 F./ 90 F./ 70 F./ 90% Sample (minutes) (%) 50% RH 90% RH 50% RH RH Control 0 22.6 2.88 4.36 21.4 24.6 Control 15 22.7 2.60 3.94 21.3 24.7 Control 30 23.3 2.71 4.15 21.5 25.0 Control 45 22.0 2.85 4.06 22.8 25.2 Average of Control 22.6 2.76 4.13 21.7 24.9 Samples Trial 1 0 20.7 1.42 2.53 14.1 15.9 Trial 1 15 21.0 1.50 2.45 14.6 16.7 Trial 1 30 20.6 1.54 2.35 13.7 15.8 Trial 1 45 21.5 1.76 2.74 16.0 18.8 Average of Trial 1 20.9 1.55 2.52 14.6 16.8 Samples

[0207] FIG. 29 shows a Cutability photograph of a Second Commercial Size Plant Production Line Control Board made with 20.0% Newsprint/8.0% Starch conditioned at 70 F./50% RH.

[0208] FIG. 30 shows a Cutability photograph of a Second Commercial Size Plant Production Line Trial 1 Board made with 15.0% Newsprint/9.0% Starch conditioned at 70 F./50% RH.

[0209] FIG. 31 shows a Cutability photograph of a Second Commercial Size Plant Production Line Trial 2 Board made with 12.0% Newsprint/10.0% Starch conditioned at 70 F./50% RH.

[0210] FIG. 32 shows a Cutability photograph of a Second Commercial Size Plant Production Line Control Board made with 20.0% Newsprint/8.0% Starch conditioned at 90 F./90% RH.

[0211] FIG. 33 shows a Cutability photograph of a Second Commercial Size Plant Production Line Trial 1 Board made with 15.0% Newsprint/9.0% Starch conditioned at 90 F./90% RH.

[0212] FIG. 34 shows a Cutability photograph of a Second Commercial Size Plant Production Line Trial 2 Board made with 12.0% Newsprint/10.0% Starch conditioned at 90 F./90% RH.

[0213] TABLE 12 summarizes Second Commercial Size Plant Production Line Trial Board Cutability Test Results. In TABLE 12, control values are averages of measurements from four boards produced 15 minutes apart on the line. Trial 1 values are averages of measurements from three boards produced 15 minutes apart on the line. Trial 2 values are averages of measurements from four boards produced 15 minutes apart on the line. Each cutability value is the average of 8 individual samples from each board with each sample cut in the machine direction.

[0214] The tests cut using an INSTRON Test Machine with custom cutting jig employing the STANLEY cutting knife blade mentioned above.

TABLE-US-00012 TABLE 12 Summary of Cutability Test Results Time after Cutability Force start of Cutability Rating 90 F./ test LOI 70 F./ 90 F./ 70 F./ 90% Sample (minutes) (%) 50% RH 90% RH 50% RH RH Control 0 22.2 2.13 3.21 19.3 20.7 Control 15 22.4 2.00 2.95 18.1 19.0 Control 30 22.0 1.61 3.34 18.3 22.1 Control 45 21.9 1.78 3.17 18.1 20.6 Average of Control 22.1 1.88 3.17 18.5 20.6 Samples Trial 1 0 22.5 1.63 3.64 18.6 23.1 Trial 1 15 22.5 1.57 4.19 17.8 21.8 Trial 1 30 23.0 1.58 3.80 17.8 22.1 Average of Trial 1 22.7 1.59 3.87 18.0 22.3 Samples Trial 2 0 20.9 1.19 2.62 17.2 18.2 Trial 2 15 20.7 1.12 2.79 16.6 18.1 Trial 2 30 20.1 1.09 2.01 16.5 17.4 Trial 2 45 20.2 1.09 2.05 15.7 16.4 Average of Trial 2 20.5 1.12 2.37 16.5 17.5 Samples

[0215] Overall there was a significant improvement in the cutability rating when comparing the control product produced using 8% starch and 20% newsprint to the improved cutability formula produced using 10% starch and 12% newsprint.

[0216] The Second Line data showed the Trial 2 formula with targets of 10% starch and 12% newsprint was a good candidate formula yielding equal or improved physicals and significantly improved cutability under both ambient and high humidity conditions.

[0217] It should be evident this disclosure is by way of example and various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.