A method for preparing an aqueous suspension may include providing a fibrous substrate comprising cellulose having a Canadian Standard freeness equal to or less than 450 cm.sup.3, and microfibrillating the fibrous substrate in an aqueous environment by grinding in the presence of a grinding medium consisting essentially of mullite. The grinding may be carried out in the absence of grindable inorganic particulate material. The grinding medium may be present in an amount of at least about 10% by volume of the aqueous environment. The microfibrillated cellulose may have a fibre steepness of from about 20 to about 50.

Methods of preparing partially dried or essentially completely dried compositions comprising microfibrillated cellulose and an inorganic particulate material may include microfibrillating a fibrous substrate comprising cellulose in an aqueous environment by grinding in the presence of an inorganic particulate material to form an aqueous composition comprising microfibrillated cellulose and inorganic particulate material, wherein the fibrous substrate comprising cellulose has a Canadian Standard freeness equal to or less than 450 cm, wherein the fibrous substrate to the inorganic particulate material are in a ratio of about 99.5:0.5 to about 0.5:99.5, and wherein the microfibrillated cellulose has a fibre steepness of from about 20 to about 50; by treating the aqueous composition comprising microfibrillated cellulose and inorganic particulate material to remove at least a portion or substantially all of the water of the aqueous composition to form a partially dried or essentially completely dried composition comprising microfibrillated cellulose and inorganic particulate material.

Methods of preparing partially dried or essentially completely dried compositions comprising microfibrillated cellulose and an inorganic particulate material may include microfibrillating a fibrous substrate comprising cellulose in an aqueous environment by grinding in the presence of an inorganic particulate material to form an aqueous composition comprising microfibrillated cellulose and inorganic particulate material, wherein the fibrous substrate comprising cellulose has a Canadian Standard freeness equal to or less than 450 cm, wherein the fibrous substrate to the inorganic particulate material are in a ratio of about 99.5:0.5 to about 0.5:99.5, and wherein the microfibrillated cellulose has a fibre steepness of from about 20 to about 50; by treating the aqueous composition comprising microfibrillated cellulose and inorganic particulate material to remove at least a portion or substantially all of the water of the aqueous composition to form a partially dried or essentially completely dried composition comprising microfibrillated cellulose and inorganic particulate material.

Methods of preparing partially dried or essentially completely dried compositions comprising microfibrillated cellulose and an inorganic particulate material may include microfibrillating a fibrous substrate comprising cellulose in an aqueous environment by grinding in the presence of an inorganic particulate material to form an aqueous composition comprising microfibrillated cellulose and inorganic particulate material, wherein the fibrous substrate comprising cellulose has a Canadian Standard freeness equal to or less than 450 cm, wherein the fibrous substrate to the inorganic particulate material are in a ratio of about 99.5:0.5 to about 0.5:99.5, and wherein the microfibrillated cellulose has a fibre steepness of from about 20 to about 50; by treating the aqueous composition comprising microfibrillated cellulose and inorganic particulate material to remove at least a portion or substantially all of the water of the aqueous composition to form a partially dried or essentially completely dried composition comprising microfibrillated cellulose and inorganic particulate material.

A method for preparing an aqueous suspension may include providing a fibrous substrate comprising cellulose having a Canadian Standard freeness equal to or less than 450 cm.sup.3, and microfibrillating the fibrous substrate in an aqueous environment by grinding in the presence of a grinding medium consisting essentially of mullite. The grinding may be carried out in the absence of grindable inorganic particulate material. The grinding medium may be present in an amount of at least about 10% by volume of the aqueous environment. The microfibrillated cellulose may have a fibre steepness of from about 20 to about 50.

A method for preparing an aqueous suspension may include providing a fibrous substrate comprising cellulose having a Canadian Standard freeness equal to or less than 450 cm.sup.3, and microfibrillating the fibrous substrate in an aqueous environment by grinding in the presence of a grinding medium consisting essentially of mullite. The grinding may be carried out in the absence of grindable inorganic particulate material. The grinding medium may be present in an amount of at least about 10% by volume of the aqueous environment. The microfibrillated cellulose may have a fibre steepness of from about 20 to about 50.

Methods of preparing partially dried or essentially completely dried compositions comprising microfibrillated cellulose and an inorganic particulate material may include microfibrillating a fibrous substrate comprising cellulose in an aqueous environment by grinding in the presence of an inorganic particulate material to form an aqueous composition comprising microfibrillated cellulose and inorganic particulate material, wherein the fibrous substrate comprising cellulose has a Canadian Standard freeness equal to or less than 450 cm, wherein the fibrous substrate to the inorganic particulate material are in a ratio of about 99.5:0.5 to about 0.5:99.5, and wherein the microfibrillated cellulose has a fibre steepness of from about 20 to about 50; by treating the aqueous composition comprising microfibrillated cellulose and inorganic particulate material to remove at least a portion or substantially all of the water of the aqueous composition to form a partially dried or essentially completely dried composition comprising microfibrillated cellulose and inorganic particulate material.

Methods of preparing partially dried or essentially completely dried compositions comprising microfibrillated cellulose and an inorganic particulate material may include microfibrillating a fibrous substrate comprising cellulose in an aqueous environment by grinding in the presence of an inorganic particulate material to form an aqueous composition comprising microfibrillated cellulose and inorganic particulate material, wherein the fibrous substrate comprising cellulose has a Canadian Standard freeness equal to or less than 450 cm, wherein the fibrous substrate to the inorganic particulate material are in a ratio of about 99.5:0.5 to about 0.5:99.5, and wherein the microfibrillated cellulose has a fibre steepness of from about 20 to about 50; by treating the aqueous composition comprising microfibrillated cellulose and inorganic particulate material to remove at least a portion or substantially all of the water of the aqueous composition to form a partially dried or essentially completely dried composition comprising microfibrillated cellulose and inorganic particulate material.

A method for preparing an aqueous suspension may include providing a fibrous substrate comprising cellulose having a Canadian Standard freeness equal to or less than 450 cm.sup.3, and microfibrillating the fibrous substrate in an aqueous environment by grinding in the presence of a grinding medium consisting essentially of mullite. The grinding may be carried out in the absence of grindable inorganic particulate material. The grinding medium may be present in an amount of at least about 10% by volume of the aqueous environment. The microfibrillated cellulose may have a fibre steepness of from about 20 to about 50.

An object of the present invention is to provide an ultrafine cellulose fiber-containing sheet, in which generation of warp (curl) is suppressed. The present invention relates to a laminated sheet having two or more layers of sheet comprising ultrafine cellulose fibers with a fiber width of 1000 nm or less, wherein among two or more layers of the sheet, when the thickness (m) of the thickest sheet is defined as T.sub.max and the thickness (m) of the thinnest sheet is defined as T.sub.min, the value of T.sub.max/T.sub.min is 3 or less, and the thickness of a single layer of the sheet is 15 m or more.