A thermal insulation product based on mineral wool, characterized in that the fibers have a micronaire of less than 10 l/min, preferably less than 7 l/min and especially between 3 and 6 l/min, and in that the material has a thermal conductivity of less than 31 mW/m.Math.K, especially less than 30 mW/m.Math.K. The parameters for obtaining this product are in particular the pressure of the burner, the rotation speed of the fiberizing spinner and the daily fiber output per spinner orifice.

The invention relates to a thermal insulation product based on mineral wool comprising mineral fibers, the product comprising two main faces and longitudinal and transverse edges perpendicular to the main faces, the product being characterized by the following orientation fractions: a longitudinal orientation fraction greater than or equal to 48%, or even 50%, along an angle of more or less 6? with respect to the plane of the main faces, when the mineral fibers are counted only in a longitudinal cross-section, and a mean orientation fraction greater than or equal to 40%, or even 45%, along an angle of more or less 6? with respect to the plane of the main faces, when the mineral fibers are counted both in a transverse cross-section and in a longitudinal cross-section.

The invention allows the insulating power of a thermal insulation product based on mineral wool to be improved without increasing its thickness.

Glass fibers have a chemical composition that includes the following constituents, in a weight content that varies within the limits defined below: SiO.sub.2 50-70%, Al.sub.2O.sub.3 0-5%, CaO+MgO 0-7%, Na.sub.2O 5-15%, K.sub.2O 0-10%, BaO 2-10%, SrO 2-10%, ZnO<2%, and B.sub.2O.sub.3 5-15%.

A nonwoven fibrous insulation product has at least a bi-modal fiber diameter distribution designed to provide the product with selected thermal insulating and physical performance properties that are affected by fiber diameter such as rigidity and recovery properties. The product is made by: forming two or more fiber groupings that each have a selected fiber diameter distribution with a selected mean fiber diameter wherein the selected fiber diameter distributions of the fiber groupings differ from each other. The fibers of the fiber groupings are intermingled and entangled together in selected percentages by weight to form a product with a selected density and thickness that exhibits selected product performance properties based on the properties of the fiber groupings and the relative percentages by weight of the fiber groupings.

The invention relates to a thermal insulation product based on mineral wool comprising mineral fibers, the product comprising two main faces and longitudinal and transverse edges perpendicular to the main faces, the product being characterized by the following orientation fractions: a longitudinal orientation fraction greater than or equal to 48%, or even 50%, along an angle of more or less 6? with respect to the plane of the main faces, when the mineral fibers are counted only in a longitudinal cross-section, and a mean orientation fraction greater than or equal to 40%, or even 45%, along an angle of more or less 6? with respect to the plane of the main faces, when the mineral fibers are counted both in a transverse cross-section and in a longitudinal cross-section. The invention allows the insulating power of a thermal insulation product based on mineral wool to be improved without increasing its thickness.

The invention relates to an uncured thermal and/or sound insulation product, based on mineral wool, advantageously on glass wool, that is in the form of a ply comprising a mineral wool layer sized by at least one binder, said sized layer having: a surface density, or basis weight, of less than or equal to 350 g/m.sup.2, preferably less than or equal to 300 g/m.sup.2, or less than or equal to 250 g/m.sup.2, and, optionally, greater than or equal to 200 g/m.sup.2, a micronaire of at most 3 under 5 grams, preferably of at most 15 l/min, better still of at most 12 l/min, and of at least 9 l/min, and the ply having a thickness of greater than 10 mm, or greater than or equal to 15 mm, or even greater than or equal to 25 mm.

The invention makes it possible to propose a thermal and/or sound insulation product that is lighter while retaining satisfactory thermal and/or sound insulation properties and a good mechanical strength.

The invention relates to an uncured thermal and/or sound insulation product, based on mineral wool, advantageously on glass wool, that is in the form of a ply comprising a mineral wool layer sized by at least one binder, said sized layer having: a surface density, or basis weight, of less than or equal to 350 g/m.sup.2, preferably less than or equal to 300 g/m.sup.2, or less than or equal to 250 g/m.sup.2, and, optionally, greater than or equal to 200 g/m.sup.2, a micronaire of at most 3 under 5 grams, preferably of at most 15 l/min, better still of at most 12 l/min, and of at least 9 l/min, and the ply having a thickness of greater than 10 mm, or greater than or equal to 15 mm, or even greater than or equal to 25 mm.

The invention makes it possible to propose a thermal and/or sound insulation product that is lighter while retaining satisfactory thermal and/or sound insulation properties and a good mechanical strength.

Provided is a method for manufacturing glass long fiber that can be produced into resin pellets without clogging of recovered glass fiber in a kneader, when glass fiber recovered from a glass fiber-reinforced resin molded product and a resin are kneaded to prepare resin pellets. In the method for manufacturing glass long fiber of the present invention, a glass raw material including glass fiber recovered from a glass fiber-reinforced resin molded product is melted into molten glass, and the molten glass is spun to form glass long fiber.

Provided is a method for manufacturing glass long fiber that can be produced into resin pellets without clogging of recovered glass fiber in a kneader, when glass fiber recovered from a glass fiber-reinforced resin molded product and a resin are kneaded to prepare resin pellets. In the method for manufacturing glass long fiber of the present invention, a glass raw material including glass fiber recovered from a glass fiber-reinforced resin molded product is melted into molten glass, and the molten glass is spun to form glass long fiber.

An article for the conversion of glass, the article being made of an alloy that contains the following elements, the proportions being indicated as percentage by weight of the alloy (limit values included): Cr 20 to 35%, Fe 1 to 6%, W 3 to 8%, Nb 0.5 to 3%, Ti 0 to 1%, C 0.4 to 1%, Co 0 to 3%, Si 0.1 to 1.5%, Mn 0.1 to 1%, the remainder being nickel and unavoidable impurities.