Abstract: A low-dielectric-constant glass fiber having a glass composition comprising, by % by weight, 45 to 60% of SiO2, 8 to 20% of Al2O3, 15 to 30% of B2O3, 0 to 5% of MgO, 5%, exclusive of 5%, to 12% of CaO, 0 to 1.0% of Li2O+Na2O+K2O, 0.5 to 5% of TiO2 and 0 to 2% of F2 is suitable for use for reinforcing a high-density printed wiring board required to have a low dielectric tangent and its peripheral members.

Abstract: When one strand, which is formed by gathering a multiplicity of glass filaments having a diameter of 9.mu. or less and formed by drawing molten glass flowed out through a multiplicity of orifices formed in the bottom portion of a bushing, is wound around a collet, the strand is wound to form a square-end cheese package by traversing the strand by a traversing device having a constant amplitude, while the strand is brought into contact with a rotative drum of a tension relaxing device to reduce the tension acting on the strand. Thus, the quality of a package of non-twisted glass yarn having a monofilament diameter of 3 to 9.mu. can be improved, a large quantity of the package can be formed, and the package can easily be transported.

Abstract: The low-dielectric-constant glass fiber of the present invention contains by weight, as a glass composition, 50 to 60% of SiO.sub.2, 10 to 20% of Al.sub.2 O.sub.3, 20 to 30% of B.sub.2 O.sub.3, 0 to 5% of CaO, 0 to 4% of MgO, 0 to 0.5% of Li.sub.2 O+Na.sub.2 O+K.sub.2 O and 0.5 to 5% of TiO.sub.2, and is preferably used as glass for printed wiring boards.

Abstract: A cake of glass fibers or the like has a waste yarn which is provided by winding a strand, which continues from an end yarn extending in contact with a winding tube, on the winding tube to cover the end yarn before a usual winding work for forming a cake on the winding cube. This cake can prevent filaments from being broken by rubbing of the strand in the innermost layer of the cake with the end yarn which is pulled into the cake when the end yarn is cut after the stand is completely wound on the winding tube.

Abstract: A method of manufacturing glass yarns includes the steps of: forming a large number of glass filaments by drawing molten glass through a large number of orifices formed on the bottom of a bushing; forming a plurality of strands by separately gathering the large number of glass filaments after a sizing agent has been applied thereto with a plurality of gathering rollers aligned in such a manner that they are separated from each other by a predetermined gap; winding the plurality of strands on one winding tube mounted on a collet while traversing the strands by one traverse motion thereby forming one cake; drawing out the ends of the plurality of strands from the outer periphery of the cake and rewinding the cake in the state wherein the strands are separated from each other by a rewinder after the cake has been air dried; and winding each of the strands as a glass yarn on a bobbin while twisting it.

Abstract: A method and apparatus for detecting conductive material contained in glass fiber, in which it is possible to detect fine conductive material contained in glass fiber under the condition that the glass fiber is running in the process of manufacturing the glass fiber, and in which it is possible to detect only the conductive material accurately without being affected by moisture or the like.