Low borosilicate glass is the so-called "neutral" glass that has been used in China for many years. Compared with the international neutral glass, the chemical composition of the two is very different. Low borosilicate glass contains low boron content, so the coefficient of linear expansion is large, so it is not as good as neutral glass in terms of strength, thermal shock resistance, and freezing resistance. The medium is scale-like and pine needle-like; the bottle is easy to break during use (especially the freeze-dried preparation).
In addition, more sodium oxide is added to low borosilicate glass during melting, so that there are relatively more sodium ions that can be released, which leads to stability and compatibility problems in contact with glass. Due to the poor material of low borosilicate glass, it is reflected that the water resistance of the inner surface is also poor. The medium borosilicate glass bottle has a very low coefficient of linear expansion, so it has good thermal stability. High hardness, good wear resistance, only a quarter of the wear resistance of ordinary glass under the same conditions, less damage to the surface of the product, and long service life. High thermal conductivity, because medium borosilicate glass will not be corroded to form an oxide film, so its thermal conductivity is high. High resistivity, because there are few monovalent metal ions in the composition of medium borosilicate glass, so the dielectric constant is small and the resistivity is high. It is a high-quality electric vacuum glass. Good chemical stability, this glass has strong resistance to water and acid attack, but poor alkali resistance.
The melting temperature of medium borosilicate glass bottles is high (1680°C). Generally, appropriate clarifiers, high-quality refractory materials, electric auxiliary heating and full electric melting technology are used; the stratification of glass liquid; temperature to improve its fluidity and reduce delamination, and adopt furnace bottom discharge device; glass liquid is easy to separate phases, choose suitable glass components, and reasonable processing technology. International neutral glass is recognized as the glass of pharmaceutical packaging materials in the world. Because the water resistance, acid resistance and alkali resistance of this glass are all first-class, it can be said to have excellent chemical stability and thermal stability. Packaging materials have incomparable advantages in ensuring quality.