An optical fiber includes: a core; a cladding layer that is lower in refractive index than the core; and a depressed layer that lies between the core and the cladding layer and that is lower in refractive index than the cladding layer, wherein: the optical fiber has an effective core area Aeff that is equal to or greater than 100 m.sup.2 and equal to or less than 129 m.sup.2, the core has a radius r1 that is equal to or greater than 5.2 m and equal to or less than 7.4 m, the core has a refractive index volume Vcore that is equal to or greater than 8.5% m.sup.2 and equal to or less than 16.5% m.sup.2, the depressed layer has a refractive index volume Vdep that is equal to or greater than 40% m.sup.2 and less than 0% m.sup.2.

An optical fiber includes: a core; a cladding layer that is lower in refractive index than the core; and a depressed layer that lies between the core and the cladding layer and that is lower in refractive index than the cladding layer, wherein: the optical fiber has an effective core area Aeff that is equal to or greater than 100 m.sup.2 and equal to or less than 129 m.sup.2, the core has a radius r1 that is equal to or greater than 5.2 m and equal to or less than 7.4 m, the core has a refractive index volume Vcore that is equal to or greater than 8.5% m.sup.2 and equal to or less than 16.5% m.sup.2, the depressed layer has a refractive index volume Vdep that is equal to or greater than 40% m.sup.2 and less than 0% m.sup.2.

A resin coating device for coating a surface of a glass fiber, includes: a point having a point hole; a die disposed directly below the point and including a first alignment portion, a second alignment portion, and a first die hole; and a first resin supply path. The second alignment portion is disposed below the first alignment portion. The first alignment portion includes a first diameter-reduced portion, and a first land portion disposed, connected to the first diameter-reduced portion, and having a constant diameter in the traveling direction. The second alignment portion includes a second diameter-reduced portion, and a second land portion, connected to the second diameter-reduced portion, and having a constant diameter in the traveling direction. The first diameter-reduced portion, the first land portion, the second diameter-reduced portion, and the second land portion are each a part of the first die hole.

A resin coating device for coating a surface of a glass fiber, includes: a point having a point hole; a die disposed directly below the point and including a first alignment portion, a second alignment portion, and a first die hole; and a first resin supply path. The second alignment portion is disposed below the first alignment portion. The first alignment portion includes a first diameter-reduced portion, and a first land portion disposed, connected to the first diameter-reduced portion, and having a constant diameter in the traveling direction. The second alignment portion includes a second diameter-reduced portion, and a second land portion, connected to the second diameter-reduced portion, and having a constant diameter in the traveling direction. The first diameter-reduced portion, the first land portion, the second diameter-reduced portion, and the second land portion are each a part of the first die hole.

Please substitute the following paragraph(s) for the abstract now appearing in the currently filed specification:

A method for producing a mineral wool product includes contacting mineral fibres with a formaldehyde-free binder composition for mineral fibres.

The invention provides use of fibre clusters in a friction material, friction materials comprising fibre clusters, and methods of making friction materials comprising fibre clusters. The fibre clusters have properties as defined in the specification.

An optical fiber comprises a glass fiber comprising a core and a cladding, and a coating resin layer covering the outer periphery of the glass fiber, wherein the average linear expansion coefficient of the coating resin layer at ?50? C. or more and 0? C. or less is 3.3?10.sup.?5/? C. or more and less than 9.0?10.sup.?5/? C.

An optical fiber comprises a glass fiber comprising a core and a cladding, and a coating resin layer covering the outer periphery of the glass fiber, wherein the average linear expansion coefficient of the coating resin layer at ?50? C. or more and 0? C. or less is 3.3?10.sup.?5/? C. or more and less than 9.0?10.sup.?5/? C.

The present invention provides a fiber sizing agent composition containing a polyester resin (A) and a reactive compound (B), wherein the polyester resin (A) is a polyester resin having an HLB of 4 to 18 and a viscosity at 30 C. of 10 to 1,000,000 Pa.Math.s, the reactive compound (B) is at least one reactive compound selected from the group consisting of blocked isocyanates, tertiary amines, tertiary amine salts, quaternary ammonium salts, quaternary phosphonium salts, and phosphine compounds, and the weight ratio of the polyester resin (A) to the reactive compound (B) [(A)/(B)] in the fiber sizing agent composition is 99.9/0.1 to 10/90.

The present invention provides a fiber sizing agent composition containing a polyester resin (A) and a reactive compound (B), wherein the polyester resin (A) is a polyester resin having an HLB of 4 to 18 and a viscosity at 30 C. of 10 to 1,000,000 Pa.Math.s, the reactive compound (B) is at least one reactive compound selected from the group consisting of blocked isocyanates, tertiary amines, tertiary amine salts, quaternary ammonium salts, quaternary phosphonium salts, and phosphine compounds, and the weight ratio of the polyester resin (A) to the reactive compound (B) [(A)/(B)] in the fiber sizing agent composition is 99.9/0.1 to 10/90.