The present disclosure relates to compositions comprising microfibrillated cellulose and improved methods for increasing the strength of ceiling tiles, flooring products, and construction products, as well as improvements in the ease of manufacturing improved ceiling tiles, flooring products and construction products containing microfibrillated cellulose.

BACKGROUND

Conventional ceiling tiles are typically composed of mineral wool and/or perlite in combination with clay filler, paper pulp and starch and frequently a retention aid

(flocculant) (e.g., polyacrylamide). These ingredients are made-up into a slurry in water and then filtered, pressed and dried to make a tile. In the manufacture of conventional ceiling tiles, starch is typically added in granular, ungelatinized ("uncooked') form, in order to be able to retain it in the tile in sufficient quantity for it to act as a binder in the finished tile. In this state it provides no strength to the wet tile, so wood or paper pulp is added in order to give sufficient strength to allow the tile to be pressed and formed in a continuous web. Gelatinization of the starch occurs during the drying process, and the tile develops its full strength during this phase.

Production processes for making mineral wool-containing and mineral wool-free ceiling tiles are known in the art in U.S. Patent Nos. and 1,769,519 and 5,395,438. In the former A composition of mineral wool fibers, fillers, colorants and a binder, in particular a starch binder, is prepared for molding or casting the body of the tile. The foregoing composition is placed on suitable trays, which are covered with paper or a metallic foil and then the composition is screeded to a desired thickness with a screed bar or roller. A decorative surface may be applied by the screed bar or roller. The trays filled with the mineral wool composition are then placed in an oven for twelve hours or more to dry or cure the composition. The dried sheets are removed from the trays and may be treated on one or both faces to provide smooth surfaces, to obtain the desired thickness and to prevent warping. The sheets are then cut into tiles of a desired size. In the latter patent, mineral wool-free ceiling tiles were prepared using expanded perlite, however maintaining the starch gel binder comprising starch, wood fiber and water which was cooked to actuate the binding properties of the starch gel.

U.S. Patent Nos. 3,246,063 and 3,307,651 disclose mineral wool acoustical tiles utilizing a starch gel as a binder. The starch gel typically comprises a thick boiling starch composition combined with calcined gypsum (calcium sulfate hemihydrate) which are added to water and cooked at 180° F.-1950 F. for several minutes to form the starch gel. Thereafter, the granulated mineral wool is mixed into the starch gel to form the aqueous composition which is used to fill the trays. Ceiling tiles produced in the manner described in these patents suffer from problems in achieving a uniform density, which is an important consideration with regard to structural integrity and strength, as well as thermal and acoustical considerations.

Mineral wool acoustical tiles are very porous which is necessary to provide good sound absorption, as described in U.S. Patent Nos. 3,498,404. Methods of manufacturing low density frothed mineral wool acoustical tiles are described in U.S. Patent No. 5,013,405 which has the disadvantage of requiring a high vacuum dewatering apparatus to collapse the bubbles formed by the frothing agent and stripping the water from the mineral fiber mass.

U.S. Patent Nos. 5,047,120 and 5,558,710 disclose that mineral fillers, such as expanded perlite, may be incorporated into the composition to improve sound absorbing properties and provide light weight. Acoustical tiles manufactured with expanded perlite typically require a high level of water to form the aqueous slurry and the expanded perlite retains a relatively high level of water within its structure.

U.S. Patent No. 5,194,206 provides compositions and methods for substituting scrap fiberglass for mineral wool in a composition and process employing a mixture of water, starch, boric acid and fire clay heated to form a gel to which shredded fiberglass is added to form a pulp. The pulp is thereafter formed into slabs and the slabs are dried to form ceiling tiles.

U.S. Patent No. 5,964,934 teaches a continuous process of making acoustical tiles in a water-felting process which includes the steps of dewatering and drying, the slurry composition comprising water, expanded perlite, cellulosic fiber and, optionally, a secondary binder, which may be starch, and optionally mineral wool, where the perlite has been treated with a silicone compound to reduce its water retention. The components are combined, mixed and a mar is formed and subjected to a vacuum step followed by drying at 350°C. It is noted that starch may also be used as a binder without pre-cooking the starch, because it forms a gel during the process of drying the basemat.

The components of conventional ceiling tiles have the following functions. Mineral wool/perlite provides fire resistance. Clay filler controls density and provides additional fire resistance. Paper or wood pulp binds together the other components while the slurry is wet. Starch is the main binder in a dry tile. The starch is added in granular (uncooked) form to the slurry; thus, the starch does not have any binding properties until it is "cooked" during the drying process.

Ceiling tile manufacturers typically add expanded perlite to ceiling tile formulations to serve as a lightweight aggregate. Adding expanded perlite provides a ceiling tile with air porosity, allowing the tile to have enhanced noise reduction coefficient (NRC) acoustical properties as well as low weight. Depending on the formulation, expanded perlite weight content may range between 10% and 70% of the ceiling tile formulation, or even higher. In certain instances, increasing the weight percentage of expanded perlite may lower the mechanical strength (e.g., the modulus of rupture) of the ceiling tile. This lowering of mechanical strength sets a limitation on the percentage of expanded perlite that may be used in some compositions, based on the targeted mechanical strength properties for the desired ceiling tile.

The present disclosure provides alternate and improved composites for addition to ceiling tiles, flooring products, and other construction products, while maintaining or improving the properties of the final ceiling tile, flooring product or construction product. The improvements are achieved through the addition of microfibrillated cellulose, and optionally one or more organic particulate materials.

The disclosure also describes economical methods of manufacturing such composites. The improved composites comprise microfibrillated cellulose and, optionally, one or more inorganic particulate material. The improved composites may allow the removal of pulp and or starch from a conventional ceiling tile composition, thereby allowing improvements in the manufacturing process of improved ceiling tiles, flooring products and construction products. Alternatively, the combination of microfibrillated cellulose and starch may result in a synergistic improvement in the binding of constituents of the ceiling tile composition. Such improved products may include high strength, high density and medium density ceiling tiles and wall boards. In some embodiments, the improvements in the process are through elimination of the "cooking" or drying step; at which gelatinization of the starch would normally occur.

SUMMARY

There is disclosed a ceiling tile, flooring product, or construction product comprising a composition of microfibrillated cellulose and, optionally, at least one inorganic particulate material. The ceiling tile, flooring product, or construction product may further comprise one or more inorganic particulate materials, for example, mineral wool and/or perlite, clay and/or other minerals, and, optionally, wood pulp, starch and/or a retention aid. The improved ceiling tile, flooring product, or construction product may eliminate in some embodiments the use of starch and/or organic particulate materials, for example mineral wool or perlite from the composition and the manufacturing process for such products. The improvements are achieved by the incorporation of microfibrillated cellulose into the ceiling tile composition. The microfibrillated cellulose may be bonded with wood pulp, if present, and/or mineral wool and/or perlite, and other organic particulate materials, if present.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

A composition for addition to a ceiling tile, flooring product, or other construction product includes microfibrillated cellulose. In certain embodiments, the composition for addition to a ceiling tile, flooring product or other construction product includes microfibrillated cellulose and at least one inorganic particulate material.

In some embodiments, a composition of microfibrillated cellulose prepared by fibrillating a cellulose-containing pulp in the presence of inorganic particulate material, as described in this specification, may be utilized as a component of the composition for

manufacturing a ceiling tile, flooring product or construction product.

In some embodiments, the composition for forming the ceiling tile, flooring product or construction product may contain an organic particulate material that is the same as, or different from, the organic particulate material used in the process of fibrillating a cellulose-containing pulp to form the microfibrillated cellulose component of the composition.

By adding a microfibrillated cellulose composition, in expense of a wood or paper pulp, to a ceiling tile, flooring product or construction product composition, for example, by adding from 0.5 % to 25 % of a microfibrillated cellulose composition, or from 0.5 % to 10 % of a microfibrillated cellulose composition, it is possible to improve the modulus of rupture of ceiling tiles. Without being bound by any particular theory or hypothesis, this improvement may be brought about due to, or due at least in part to, the microfibrillated cellulose bonding with the wood or paper pulp in the ceiling tile, if present, or with the other inorganic particulate material components of the product. In some embodiments, it is even possible to totally eliminate the incorporation of wood or paper pulp into the ceiling tile, flooring product or construction product composition altogether.

By adding microfibrillated cellulose composition in expense of pulp to ceiling tile, flooring product or construction product compositions, for example, by adding from 0.5 % to 25 % of the microfibrillated cellulose composition, or from 0.5 % to 10 % of the microfibrillated cellulose composition, it is possible to improve the flexural strength of a ceiling tile, flooring product or construction product. When wood or paper pulp is present, the improvements in flexural strength may be due to, or due at least in part to, the microfibrillated cellulose bonding with the wood or paper pulp in the product. When wood or paper pulp is eliminated, the microfibrillated cellulose, nevertheless, improves tensile strength of the ceiling tile, flooring product, or construction product.

Microfibrillated cellulose has been found suitable to replace both the wood pulp and the starch typically present in conventional ceiling tile, flooring product or construction product.

Microfibrillated cellulose has also been found suitable to replace inorganic particulate material components present in conventional ceiling tiles, flooring products or construction products.

Microfibrillated cellulose has also been found suitable together with starch to improve the binding of inorganic and cellulosic constituents in compositions for the manufacture of ceiling tiles, flooring products and construction products.

Microfibrillated cellulose provides wet strength during formation and acts as a strong binder in the dry tile. As noted in the previous paragraph, the fact that strong ceiling tiles, flooring products or construction products can be made without pulp suggests that the microfibrillated cellulose binds equally well to the inorganic particulate material components of the ceiling tiles, flooring products or construction products.

Alternatively, the incorporation of microfibrillated cellulose into the ceiling tile, flooring product or construction product has been found suitable to increase the mineral wool (fibre) and/or perlite content of the ceiling tile, flooring product or construction product.

Taking advantage of the beneficial properties due to incorporation of a microfibrillated cellulose-containing composition into the ceiling tile base composition, it is possible to increase the perlite content of the ceiling tile, flooring product or construction product, e.g., increase by at least 1 %, or by at least 5 %, or by at least 10 %, or by at least 15 %, or by at least 20%, in expense of pulp. Increasing the perlite content may decrease the weight and density of the ceiling tile, flooring product or construction product, e.g., by at least 1 %, or by at least 2 %, or by at least 5 %, or by at least 10%. This may, in turn, increase the air porosity of the ceiling tile, flooring product or construction product and, in particular with regard to ceiling tiles, the improved air porosity may thereby improve the ceiling tile's acoustic properties (e.g., sound absorption). Additionally, by increasing the perlite content in the ceiling tile, flooring product or construction product

composition along with the addition of a microfibrillated cellulose composition, drainage of water may be improved and the drying time of the final product may be decreased, thereby increasing production speed of the final products.

Reducing weight of ceiling tiles by adding a microfibrillated cellulose composition may also improve storage capability in warehouses.

In addition to ceiling tiles, and flooring products, the microfibrillated cellulose composition may be used, as a component in other construction products, including, for example: cement board; gypsum board/plasterboard; insulation core of structural insulated panels and fiberboards; fiberboards of all descriptions (including oriented particle board); cements and concretes; sound proofing; textured and masonry paints;

paints (as a rheology modifier); antimicrobial fire retardant wall boards; sealants and adhesives and caulks; insulation; partial or complete asbestos replacement; and foams.

The ceiling tile

Perlite-based ceiling tiles

In certain embodiments comprising, a ceiling tile base composition comprises perlite. In such embodiments, a ceiling tile, based on the total dry weight of the ceiling tile, may comprise at least about 30 % by weight perlite, at least about 35 % by weight perlite, at least about 40 % by weight perlite, at least about 45 % by weight perlite, at least about 50 % by weight perlite, at least about 55 % by weight perlite, at least about 60 % by weight perlite, at least about 65 % by weight perlite, at least about 70 % by weight perlite, at least about 75 % by weight perlite, at least about 80 % by weight, perlite, at least about 85 % by weight perlite, or at least about 90 % by weight perlite. In such embodiments, the ceiling tile may comprise from about 30 % by weight to about 90 % by weight perlite, based on the total weight of the ceiling tile, for example, from about 35 % by weight to about 85 % by weight, from about 55 % by weight to about 85 % by weight, or from about 60 % by weight to about 80 % by weight, or from about 65 % by weight to about 80 % by weight, or from about 70 % by weight to about 80 % by weight, or up to about 79 % by weight, or up to about 78 % by weight, or up to about 77 % by weight, or up to about 76 % by weight, or up to about 75 % by weight perlite, based on the total dry weight of the ceiling tile.

In certain embodiments, including for example, the embodiments described above in which the ceiling tile comprises perlite and microfibrillated cellulose, the ceiling tile further comprises wood or paper pulp. For the avoidance of doubt, the wood or paper pulp is distinct from the microfibrillated cellulose composition.

Advantageously, by including a microfibrillated cellulose composition, the amount of wood or paper pulp in the ceiling tile may be reduced or eliminated whilst maintaining or improving one or more mechanical properties of the ceiling tile, such as flexural strength and/or modulus of rupture.

In certain embodiments, when wood or paper pulp is present, the ceiling tile comprises from about 0.1 % by weight to about 30 % by weight wood pulp, based on the total dry weight of the ceiling tile. In certain embodiments, the ceiling tile comprises from about 1 % by weight to about 30 % by weight wood or paper pulp, for example, from about 5 % by weight to about 25 % by weight wood or paper pulp, or from about 5 % by weight to about 20 % by weight wood or paper pulp, or from about 5 % by weight to about 15 % by weight wood or paper pulp, or from about 5% by weight to about 10% by weight wood or paper pulp.

In certain additional embodiments, the ceiling tile comprises up to about 40 % by weight wood or paper pulp, for example, up to about 35 % by weight wood or paper pulp, or up to about 30 % by weight wood or paper pulp, or up to about 25 % by weight wood or paper pulp, or up to about 22.5 % by weight wood or paper pulp, or up to about 20 % by weight wood or paper pulp, or up to about 17.5 % by weight wood or paper pulp, or up to about 15 % by weight wood or paper pulp, or up to about 12.5 % by weight wood or paper pulp, or up to about 10 % by weight wood or paper pulp. In certain embodiments wood or paper pulp is entirely eliminated from the ceiling tile.

In certain embodiments, including for example, the embodiments described above in which the ceiling tile comprises perlite, microfibrillated cellulose and wood or paper pulp, the ceiling tile comprises up to about 50 % by weight of a microfibrillated cellulose composition, based on the total dry weight of the ceiling tile. The microfibrillated cellulose may or may not comprise an inorganic particulate material. When the microfibrillated cellulose composition added to the ceiling tile composition comprises an inorganic particulate material, the inorganic particulate material may be the same as, or different from, other inorganic particulate materials present in the ceiling tile

composition.

In other embodiments, including the foregoing embodiments comprising perlite, a microfibrillated cellulose composition and wood or paper pulp, the ceiling tile comprises from 0.1 % by weight to about 40 % by weight of the microfibrillated cellulose composition, for example, from about 0.5 wt. % to about 30 % by weight, or from about 1 wt. % to about 25 % by weight, or from about 2 % by weight to about 20 % by weight, or from about 3 % by weight to about 20 % by weight, or from about 4 % by weight to about 20 % by weight, or from about 5 % by weight to about 20 % by weight, or from about 7.5 % by weight to about 20 % by weight, or from about 10 % by weight to about 20 % by weight, or from about 12.5 % by weight to about 17.5 % by weight of the microfibrillated cellulose composition, based on the total dry weight of the ceiling tile.

In certain other embodiments, including for example, the embodiments described above in which the ceiling tile comprises perlite, microfibrillated cellulose and wood paper pulp, the ceiling tile comprises from about 0.1 % by weight to about 5 % by weight of the microfibrillated cellulose composition, based on the total dry weight of the ceiling tile, for example, from about 0.5 % by weight to about 5 %, or from about 1 % by weight to about 4 % by weight, or from about 1.5 % by weight to about 4 % by weight, or from about 2 % by weight to about 4 % by weight. Even addition of such relatively minor amounts of a microfibrillated cellulose composition may enhance one or more mechanical properties (e.g., flexural strength) of the ceiling tile. In such embodiments, the ceiling tile may comprise from about 10 % by weight to about 30 % by weight wood or paper pulp and up to about 85 % by weight perlite, for example, from about 15 % by weight to about 25 % by weight wood or paper pulp and up to about 80 % by weight perlite, or from about 20 % by weight to about 25 % by weight wood or paper pulp and up to about 75 % by weight perlite.

As described herein, the microfibrillated cellulose composition may comprise an inorganic particulate material, which may or may not have been added during

manufacture of the microfibrillated cellulose composition. Based on the total dry weight of the microfibrillated cellulose composition, the composition may comprise from about 1 % by weight to about 99 % by weight microfibrillated cellulose and from 99 % by weight to about 1 % by weight inorganic particulate material (e.g., calcium carbonate or kaolin). In many instances, the ceiling tile composition may comprise some clay (e.g., kaolin), calcium carbonate or some other organic particulate material. In such situations, the microfibrillated cellulose composition may be produced using the same inorganic particulate material that is present in the ceiling tile base composition. Thus, the microfibrillated cellulose composition can be used without altering the base ceiling tile composition.

Alternatively, in some other instances where there is either no other organic particulate material or very little in the base ceiling tile composition, a high percentage of pulp microfibrillated cellulose composition with little to no inorganic particulate material present or even an organic particulate material-free microfibrillated cellulose composition may be beneficial for incorporation in the base ceiling tile composition.

In some embodiments, including the foregoing microfibrillated cellulose compositions with reduced or essentially no inorganic particulate material present in such composition, ratios of 1:1 microfibrillated cellulose to inorganic particulate material (by weight), or 3:1 microfibrillated cellulose to inorganic particulate material, or even 166:1 microfibrillated cellulose to inorganic particulate material, may be suitable for incorporation into the base ceiling tile composition.

In certain embodiments, including for example, the embodiments described above in which the ceiling tile comprises perlite and microfibrillated cellulose, and does not comprise wood or paper pulp, the ceiling tile comprises up to about 50 % by weight of the microfibrillated cellulose composition, based on the total dry weight of the ceiling tile. The microfibrillated cellulose may or may not comprise an inorganic particulate material. When the microfibrillated cellulose composition added to the ceiling tile composition comprises an inorganic particulate material, the inorganic particulate material may be the same as, or different from, other inorganic particulate materials in the ceiling tile composition.

In certain embodiments, including the embodiments described above that contain perlite, and microfibrillated cellulose, but do not contain wood or paper pulp, the ceiling tile

comprises from 0.1 % by weight to about 40 % by weight of the microfibrillated cellulose composition, for example, from about 0.5 wt. % to about 30 % by weight, or from about 1 wt. % to about 25 % by weight, or from about 2 % by weight to about 20 % by weight, or from about 3 % by weight to about 20 % by weight, or from about 4 % by weight to about 20 % by weight, or from about 5 % by weight to about 20 % by weight, or from about 7.5 % by weight to about 20 % by weight, or from about 10 % by weight to about 20 % by weight, or from about 12.5 % by weight to about 17.5 % by weight of the microfibrillated cellulose composition, based on the total dry weight of the ceiling tile.

In certain other embodiments, including for example, the embodiments described above in which the ceiling tile comprises perlite and does not comprise wood or paper pulp, the ceiling tile comprises from about 0.1 % by weight to about 5 % by weight of the microfibrillated cellulose composition, based on the total dry weight of the ceiling tile, for example, from about 0.5 % by weight to about 5 %, or from about 1 % by weight to about 4 % by weight, or from about 1.5 % by weight to about 4 % by weight, or from about 2 % by weight to about 4 % by weight. Even addition of such relatively minor amounts of the microfibrillated cellulose may enhance one or more mechanical properties (e.g., flexural strength) of the ceiling tile.

As described herein, the microfibrillated cellulose composition may comprise an inorganic particulate material, which may or may not have been added during

manufacture of the microfibrillated cellulose composition. Based on the total dry weight of the microfibrillated cellulose composition, the composition may comprise from about 1 % by weight to about 99 % by weight microfibrillated cellulose and from 99 % by weight to about 1 % by weight inorganic particulate material (e.g., calcium carbonate or kaolin). In many instances, the ceiling tile composition may comprise some clay (e.g., kaolin), calcium carbonate or some other organic particulate material. In such situations, the microfibrillated cellulose composition may be produced using the same inorganic particulate material that is present in the ceiling tile base composition. Thus, the microfibrillated cellulose composition can be used without altering the base ceiling tile composition.

Alternatively, in some other instances where there is either no other organic particulate material or very little in the base ceiling tile composition, a high percentage of pulp microfibrillated cellulose composition with little to no inorganic particulate material present or even an organic particulate material-free microfibrillated cellulose composition may be beneficial for incorporation in the base ceiling tile composition.

In some embodiments, including the foregoing microfibrillated cellulose compositions with reduced or essentially no inorganic particulate material present in such composition, ratios of 1:1 microfibrillated cellulose to inorganic particulate material (by weight), or 3:1 microfibrillated cellulose to inorganic particulate material, or even 166:1 microfibrillated cellulose to inorganic particulate material, may be suitable for incorporation into the base ceiling tile composition.

Mineral Wool (or Mineral Fibres)

In certain embodiments, including for example, the embodiments described above in which the ceiling tile comprises perlite and microfibrillated cellulose, and does not comprise wood or paper pulp, the ceiling tile may further comprise mineral wool. The terms mineral wool and mineral fibres are used interchangeably herein.

Mineral wool, sometimes also referred to as rock wool or stone wool, is a substance resembling matted wool, which is made from inorganic mineral material. It is routinely used in insulation and packaging materials. Mineral wools may be prepared as glass wools, stone wools or ceramic fiber wools. Thus, mineral wool is a generic name for fibrous material that may be formed by spinning or drawing molten minerals. Mineral wool is also known a mineral fiber, mineral cotton, and vitreous fiber. Mineral wools have excellent fire resistance properties, where the material is used in a variety of applications.

Rock wool is made from basalt rock and chalk. These minerals are melted together at very high temperatures (e.g., 1600 °C into lava, which is blown into a spinning chamber and pulled into fibers resembling "cotton candy."

In certain embodiments, the ceiling tiles may comprise mineral wool and perlite and up to about 50 % by weight of a microfibrillated cellulose composition, based on the total dry weight of the ceiling tile. The microfibrillated cellulose composition may or may not comprise an inorganic particulate material. When the microfibrillated cellulose composition added to the ceiling tile composition comprises an inorganic particulate material, the inorganic particulate material may be the same as, or different from, other inorganic particulate materials in the ceiling tile composition.

In certain embodiments, including the foregoing embodiments comprising perlite, mineral wool and a microfibrillated cellulose composition, the ceiling tile comprises from 0.1 % by weight to about 40 % by weight of a microfibrillated cellulose

composition, for example, from about 0.5 wt. % to about 30 % by weight, or from about 1 wt. % to about 25 % by weight, or from about 2 % by weight to about 20 % by weight, or from about 3 % by weight to about 20 % by weight, or from about 4 % by weight to about 20 % by weight, or from about 5 % by weight to about 20 % by weight, or from about 7.5 % by weight to about 20 % by weight, or from about 10 % by weight to about 20 % by weight, or from about 12.5 % by weight to about 17.5 % by weight of the microfibrillated cellulose composition, based on the total dry weight of the ceiling tile.

In certain other embodiments, including for example, the embodiments described above in which the ceiling tile comprises perlite and mineral wool, and a microfibrillated cellulose composition, the ceiling tile product comprises from about 0.1 % by weight to about 10 % by weight of the microfibrillated cellulose composition, based on the total dry weight of the ceiling tile, for example, from about 0.5 % by weight to about 8 %, or from about 1 % by weight to about 6 % by weight, or from about 1.5 % by weight to about 4 % by weight, or from about 2 % by weight to about 4 % by weight.

In certain embodiments, the ceiling tile further comprises mineral wool in an amount up to about 95 % by weight based on the total dry weight of the ceiling tile, or up to about 90 % by weight based on the total dry weight of the ceiling tile, or up to about 85 % by weight based on the total dry weight of the ceiling tile, or up to about 80 % by weight based on the total dry weight of the ceiling tile, or up to about 75 % by weight based on the total dry weight of the ceiling tile, or up to about 70 % by weight based on the total dry weight of the ceiling tile or up to about 65 % by weight based on the total dry weight of the ceiling tile, or up to about 60 % by weight based on the total dry weight of the ceiling tile, or up to about 55 % by weight based on the total dry weight of the ceiling tile, or up to about 50 % by weight based on the total dry weight of the ceiling tile, or up to about 55 % by weight based on the total dry weight of the ceiling tile, or up to about 50 % by weight based on the total dry weight of the ceiling tile, or up to about 45 % by weight based on the total dry weight of the ceiling tile, or up to about 40 % by weight based on the total dry weight of the ceiling tile, or up to about 35 % by weight based on the total dry weight of the ceiling tile, or for example from about 10 % by weight to about 75 % by weight, or about 15% by weight to about 65 % by weight, or about 20% by weight to about 55 % by weight, or about 25% by weight to about 45 % by weight, based on the total dry weight of the ceiling tile product.

Such embodiments, including those described above for ceiling tile, comprising mineral wool, perlite and a microfibrillated cellulose composition, may comprise perlite in an amount up to 65 % by weight, based on the total dry weight of the ceiling tile, for example from 30 % by weight to 60 % by weight, or from 35 % by weight to 55 % by weight, or from 35 % by weight to 45 % by weight. Even addition of relatively minor amounts of a microfibrillated cellulose composition to ceiling tiles may enhance one or more mechanical properties (e.g., flexural strength) of such products.

In certain embodiments, the ceiling tile comprising the microfibrillated cellulose composition has a flexural strength of at least about 400 kPa, for example, at least about 450 kPa, or at least about 500 kPa, or at least about 550 kPa, or at least about 600 kPa, or at least about 650 kPa, or at least about 700 kPa, or at least about 750 kPa, or at least about 800 kPa, or at least about 850 kPa, or at least about 900 kPa.

In certain embodiments, including the embodiments described above comprising mineral wool, perlite and a microfibrillated cellulose composition up to about 50 % by weight of the microfibrillated cellulose composition may be present, based on the total dry weight of the ceiling tile. In such embodiments, the microfibrillated cellulose composition may comprise an inorganic particulate material, which may or may not have been added during manufacture of the microfibrillated cellulose composition. Based on the total dry weight of the microfibrillated cellulose composition, the composition may comprise from about 1 % by weight to about 99 % by weight microfibrillated cellulose and from 99 % by weight to about 1 % by weight inorganic particulate material (e.g., calcium carbonate).

In certain embodiments the ceiling tile may comprise mineral wool or the product may eliminate mineral wool. Mineral wool may be component of the composition for the ceiling tile in a broad range of from about 0 wt.% to about 75 wt.% of mineral wool, based on the total dry weight of the ceiling tile in combination with a microfibrillated cellulose composition for example, from about 0.5 wt. % to about 40 % by weight, or from about 1 wt. % to about 35 % by weight, or from about 2 % by weight to about 30 % by weight, or from about 3 % by weight to about 25 % by weight, or from about 4 % by weight to about 20 % by weight, or from about 5 % by weight to about 15 % by weight, or from about 6% by weight to about 20 % by weight, or from about 8 % by weight to about 30 % by weight, or from about 12.5 % by weight to about 17.5 % by weight of the microfibrillated cellulose composition, based on the total dry weight of the ceiling tile.

In the foregoing embodiments, the ceiling tile may comprise wood or paper pulp with or without the addition of starch. When present the wood or paper pulp may be present in an amount of up to 35% by weight with mineral wool being present in an amount up to about 55% by weight and a microfibrillated cellulose composition of up to about 10%. If starch is present as a binder, or additional organic particulate materials are present in the ceiling tile base composition, the percentages of the remaining components may be suitably adjusted.

In further embodiments, the ceiling tile may comprise perlite, mineral wool and a microfibrillated cellulose composition, with or without the addition of starch. When present the perlite may be present in an amount of up to 45% by weight, with mineral wool being present in an amount up to about 35% by weight and a microfibrillated cellulose composition of up to about 20%, by weight based on the total dry weight of the ceiling tile. If starch is present as a binder, the percentages of the remaining components are suitably adjusted. Similarly, if inorganic particulate material is present, the remaining components are suitably adjusted, or in some instances may be eliminated from the composition.

In certain other embodiments, including for example, the embodiments described above in which the ceiling tile comprises perlite, mineral wool and a microfibrillated cellulose composition, the ceiling tile comprises from about 0.1 % by weight to about 8 % by weight of the microfibrillated cellulose composition, based on the total dry weight of the ceiling tile, for example, from about 0.5 % by weight to about 5 %, or from about 1 % by weight to about 4 % by weight, or from about 1.5 % by weight to about 4 % by weight, or from about 2 % by weight to about 4 % by weight. Even addition of such relatively minor amounts of the microfibrillated cellulose may enhance one or more mechanical properties (e.g., flexural strength) of the ceiling tile.

The microfibrillated cellulose composition can be prepared in accordance with the procedures outlined in this specification including by fibrillating cellulose-containing pulps together with an organic particulate material. Based on the total dry weight of such microfibrillated cellulose compositions, the inorganic particulate may constitute up to about 99 % of the total dry weight, for example, up to about 90 %, or up to about 80 wt.%, or up to about 70 wt.%, or up to about 60 wt. %, or up to about 50 wt.%, or up to about 40 %, or up to about 30 %, or up to about 20 %, or up to about 10 %, or up to about 5 % of the total dry weight, or up to about 1 % or up to 0.5% of the total dry weight of the microfibrillated cellulose composition.

Alternatively, the microfibrillated cellulose composition may be essentially free of organic particulate material and comprise no more than about 0.6 wt. % of inorganic particulate material.

Based on the total dry weight of the microfibrillated cellulose composition, the microfibrillated cellulose may constitute up to about 99.4 % of the total dry weight, for example, up to about 99 %, up to about 90 %, or up to about 80 wt.%, or up to about 70 wt.%, or up to about 60 wt. %, or up to about 50 wt.%, or up to about 40 %, or up to about 30 %, or up to about 20 %, or up to about 10 %, or up to about 5 % of the total dry weight of the microfibrillated cellulose composition.

In certain embodiments, the weight ratio of inorganic particulate material to

microfibrillated cellulose in the microfibrillated cellulose composition is from about 10:1 to about 1 :2, for example, from about 8:1 to about 1 :2, or from about 6:1 to about 2:3, or from about 5: 1 to about 2:3, or from about 5:1 to about 1 :1, or about 4:1 to about 1 : 1, or from about 3 : 1 to about 1.1 , or from about 2:1 to about 1.1 , or about 1:1.

In certain embodiments, the microfibrillated cellulose composition is substantially free of inorganic particulate material. By substantially free, of inorganic particulate material is meant less than about 0.6% by weight, less than 0.5% by weight, less than 0.4% by weight, less than 0.3% by weight, less than 0.2% by weight, less than 0.1% by weight of inorganic particulate material based upon the total dry weight of the microfibrillated cellulose composition.

Flooring Products and Other Construction Products

In certain embodiments, a flooring product or construction product comprises up to about 10 % by weight microfibrillated cellulose (i.e., derived from the microfibrillated cellulose composition which may or may not comprise inorganic particulate material), based on the total dry weight of the flooring product or construction product, for example, up to about 9 % by weight, or up to about 8 % by weight, or up to about 7 % by weight or up to about 6 % by weight, or up to about 5 % by weight, or up to about 4 % by weight, or up to about 3 % by weight, or up to about 2 % by weight, or up to about 1 % by weight microfibrillated cellulose. In certain embodiments, the flooring product or construction product comprises at least about 0.1 % by weight microfibrillated cellulose, for example, at least about 0.25 % by weight, or at least about 0.5 % by weight microfibrillated cellulose. The microfibrillated cellulose may or may not comprise an inorganic particulate material. When the microfibrillated cellulose composition added to the flooring product or construction product composition comprises an inorganic particulate material, the inorganic particulate material may be the same as, or different from, other inorganic particulate materials in the flooring product or construction product

composition.

Compositions and methods of preparing flooring materials and construction materials may be formulated and prepared in according with the compositions and methods described in this specification for ceiling tiles. An exemplary fibreboard composition is presented in Example 5. The fibreboard was made in accordance with the procedures used to produce ceiling tiles as set forth in Example 1.

WHAT IS CLAIMED IS:

A construction product comprising a composition of microfibrillated cellulose and one or more inorganic particulate material.

2. The construction product of claim 1, wherein the construction product is a ceiling tile.

3. The ceiling tile of claim 2, wherein the ceiling tile further comprises mineral wool or perlite, or both mineral wool and perlite.

4. The ceiling tile of claim 2 or 3, wherein the ceiling tile further comprises wood pulp or paper pulp and, optionally, starch and/or a latex binding agent.

5. The ceiling tile of any claims 2-4, wherein the ceiling tile comprises up to about 50 % by weight of the microfibrillated cellulose, based on the total dry weight of the ceiling tile.

6. The ceiling tile of any of claims 2-5, wherein the ceiling tile comprises up to about 25 % by weight of the microfibrillated cellulose composition, based on the total dry weight of the ceiling tile.

7. The ceiling tile of any of claims 2-6, wherein the ceiling tile comprises up to about 10 % by weight of the microfibrillated cellulose composition, based on the total dry weight of the ceiling tile.

8. The ceiling tile according to any one of claims 2-7, wherein the ceiling tile comprises up to about 80 % by weight perlite or mineral wool, or both perlite and mineral wool, based on the total dry weight of the ceiling tile.

9. The ceiling tile according to any one of claims 4-7, wherein the ceiling tile comprises up to about 25 % by weight wood pulp or paper pulp, based on the total dry weight of the ceiling tile.

10. The ceiling tile according to claim 9, wherein the ceiling tile comprises up to about 10 % by weight wood pulp or paper pulp, based on the total dry weight of the ceiling tile.

11. The ceiling tile according to any of claims 2- 10, wherein the ceiling tile has a flexural strength which is improved compared to a ceiling tile which does not comprise microfibrillated cellulose.

12. The ceiling tile according to claim 11 , wherein the ceiling tile has a flexural strength of at least about 400 kPa.

13. The ceiling tile according to claim 8, wherein the ceiling tile further comprises: (ii) up to about 20 % by weight of microfibrillated cellulose, based on the total dry weight of the ceiling tile, for example, from about 10 % by weight to about 20 % by weight, or from about 1 % by weight to about 10 % by weight of the microfibrillated cellulose composition; and/or (i) up to 20 % by weight of wood pulp or paper pulp, based on the total dry weight of the ceiling tile, for example, from about 5 % by weight to about 20 % by weight wood pulp, for example, from about 5 % by weight to about 15 % by weight wood pulp, or from about 8 % by weight to about 12 % by weight pulp.

14. The construction product or ceiling tile according to any preceding claim, wherein the microfibrillated cellulose composition comprises microfibrillated cellulose and inorganic particulate material in a weight ratio of from about 5: 1 to about 1 : 166.

15. The ceiling tile according to any of claims 2-14, wherein the inorganic particulate, when present, is or comprises calcium carbonate or kaolin.

16. The construction product or ceiling tile according to any preceding claim, wherein the microfibnllated cellulose has a fibre steepness of from about 20 to about 50.

17. Use of a microfibnllated cellulose composition in a construction product, for example, a ceiling tile.

18. Use according to claim 17, for improving the flexural strength of the ceiling tile.

19. A method for making a construction product according to any preceding claim, comprising combining the microfibnllated composition with other component(s) of the construction product and forming the construction product therefrom.

20. A method for making a ceiling tile according to any of claims 2-19, comprising combining the microfibrillated cellulose composition with other component(s) of the ceiling product and forming a ceiling tile therefrom.