A funnel glass containing PbO for a cathode ray tube, wherein when the composition is represented by wt % based on oxides, the content of SrO is at least 1.0 wt %, the content of BaO is at least 1.0 wt %, and the ratio of the content of PbO to the total amount of PbO, SrO, BaO, CaO and MgO, is at most 0.69, and whereby the lead elution A of the glass as measured by the following method A is at most 1.0 .mu.g/cm.sup.2, and the X-ray absorption coefficient at a wavelength of 0.6 .ANG. is at least 40 cm.sup.-1 : Method A: The glass is immersed in distilled and deionized water at 90.degree. C. for 20 hours, whereupon the glass is taken out, and the amount of lead in the distilled and deionized water is measured by inductively coupled plasma emission spectrometry, and the measured value of the amount of lead is divided by the surface area of the glass, and the product is taken as the lead elution A.
In order to suppress production of devitrifying stones such as barium disilicate and strontium silicate and to achieve a high X-ray absorbability, a CRT panel glass does not substantially contain PbO and contains, in mass percent, 9-9.5% SrO and 8.5-9% BaO. In addition, the value of SrO/(SrO+BaO) is set to 0.50-0.53. Therefore, the CRT panel glass has an X-ray absorption coefficient of 28.0 cm.sup.-1 or more at 0.6 .ANG..
A CRT funnel of a non beam-index type is made of a lead glass which contains 10-30 mass % of PbO and has an X-ray absorption coefficient of 40 cm.sup.-1 or more at 0.6 .ANG.. The lead glass further contains Sb.sub.2 O.sub.3 and an additive including at least one of CeO.sub.2 and SnO.sub.2. In case where the additive includes CeO.sub.2, it is preferable that the content of CeO.sub.2 is not smaller than 0.01 mass % and is smaller than 0.5 mass %. In case where the additive includes SnO.sub.2, the content of SnO.sub.2 preferably falls within a range of 0.001-2 mass %.
A glass panel for a color cathode ray tube, which has a linear absorption coefficient of X-ray with a wavelength of 0.06 nm of from 30 to 38 cm.sup.-1 and which has a layer having a compression stress of at least 70 MPa formed by a chemical strengthening method at least at short axis end portions and/or long axis end portions of the outer surface of a face portion and at a center portion of the inner surface of the face portion.
A method for producing CRT funnel glass having a glass composition containing MgO, CaO, SrO, BaO and ZnO as essential components. Further, the total content of MgO, CaO, SrO, BaO and ZnO falls within a range of 5 to 13 mass %. As a glass material of the CRT funnel glass, CRT panel glass or CRT neck glass may be used. The method comprises preparing the glass material so as to contain MgO, CaO, SrO, BaO, and ZnO as essential components and so that the total content of MgO+CaO+SrO+BaO+ZnO falls within a range of 5 to 13 mass %; and melting the glass material.
A glass funnel suitable for a chemical strengthening method of an electric field application type without impairing the safety of a cathode ray tube. A glass funnel for a cathode ray tube, characterized in that glass at a body portion 3 contains at least Na.sub.2O and K.sub.2O, the conductivity of said glass at the strain point is at least 4.times.10.sup.-6 S/cm, the conductivity at 150.degree. C. is at most 5.times.10.sup.-12 S/cm, and a compressive stress layer is formed by a chemical strengthening method on at least part of the outer surface of the body portion 3.
