JPS61151040A - Alkali-resistant glass - Google Patents

Abstract

PURPOSE:To obtain an alkali-resistant glass useful especially as cement- reinforcing glass-fiber and light-weight aggregate for building material, by compounding Cr2O3, BaO, MgO and P2O5 at specific ratios. CONSTITUTION:The objective alkali-resistant glass is composed of 10-25(mol%) Cr2O3, 0-45% BaO, 0-45% MgO and 30-60% P2O5 provided that BaO+MgO is >=25%. The durability, stability and meltability of the glass can be improved by adding <=10mol% each of Li2O, Na2O, K2O, CaO, SrO, ZnO, SnO2, PbO, MnO, B2O3, Al2O3, Fe2O3, GeO2, ZrO2, TiO2, La2O3, etc., provided that the sum of the additives is <=15mol%.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Industrial Application Field The present invention relates to glass with excellent alkali resistance, and is particularly suitable for use as glass fiber for reinforcing cement and aggregate for lightweight refractories for building materials. It is used as a substitute for alkali-resistant glass.

b. Prior art Traditionally, 5, which has relatively high alkali resistance, has been used as aggregate for glass fibers for cement reinforcement and lightweight refractories for building materials.
iOz-CaO-ZrOz-RzO (R is an alkali metal) type glass and SiOz-CaO-AIzOm-RzO type glass are used, but even these glasses have problems with their alkali resistance, and there is a need for better alkali resistance. is desired. In addition, the main component that forms the glass skeleton of conventional alkali-resistant glass is 5iOz, but there is also a problem with the solubility of zircon (ZrOz/SiO2), and from the perspective of energy saving, a glass with better solubility is desired. ing.

C0 Purpose of the Invention The present invention provides an alkali-resistant glass that is sufficiently resistant to use under strong alkaline conditions, such as glass fiber for cement reinforcement and aggregate for lightweight refractories for building materials, and that is excellent in melting and moldability. The purpose is to provide.

d1 Constitution of the invention The present invention is expressed in mol%, CrzOs 10 ~25BaOO~4
It is an alkali-resistant glass having a composition of 5 Mg0 O~45 P20@30~60 and more than BaO+MgO25.

The alkali-resistant glass of the present invention has extremely good alkali resistance because it contains large amounts of CrzOs, BaO, and MgO, which are difficult to dissolve in alkaline aqueous solutions.

In particular, it has been found that the effect of Cr2O3 on improving alkali resistance becomes significant when the content thereof is 10 mol % or more. In other words, 5102 series glass has Cr2
The content of O3 is at most 10 mol%, but by using phosphate glass, it is possible to more than double the content, which has a great effect on improving alkali resistance. did it. This seems to be due to the formation of CrPO, which is poorly soluble in water and highly stable.

On the other hand, it is generally said that phosphate glass has poor alkali resistance compared to silicate glass, but as in the glass of the present invention, oxides such as CrzOs, 13aO, MgO, etc. By adding it, it was possible to obtain better alkali resistance than silicate glass.

Each component of the glass used in the present invention is limited to the above range, and the reason for the limitation will be shown below.

That is, when Cr2O3 content is less than 10 mol%, the alkali resistance of the glass decreases, and when it is more than 25 mol%, the devitrification of the glass increases, making it difficult to mold the glass.

When BaO and MgO each exceed 45 mol%,
The devitrification of the glass increases. Moreover, when [laO+MgO is less than 25 mol%, alkali resistance deteriorates.

When P2O5 is less than 30 mol%, the devitrification of the glass increases and it becomes difficult to mold. When the amount is more than 60 mol%, alkali resistance decreases.

In addition to the above components, the glass composition also contains 10 mol% or less of zO, NazO, zO, CaO, SrO, ZnO,
5nOz, PbO, MnO.

B zOs p A lz Os HF etas H
Ge0z l Z rK HT I O21LazOs
Although the addition of these components is effective in improving the durability and stability of the glass or improving the melting properties, the total amount of the additive components exceeds 5 mol% per month. Then, the alkali resistance of the glass decreases or the moldability deteriorates.

e. A batch calculated to have a glass composition as shown in Tables 1 and 2 of Examples was prepared in a predetermined proportion using phosphoric acid (85% 1I3POJ and carbonate and oxide raw materials as special grade reagents). After mixing thoroughly, add 1 ml to remove moisture.
It was dried at 20°C for about 10 hours, placed in a platinum crucible, and melted in an electric furnace at about 1200-1400°C for about 2 hours. After melting, the glass is poured into a mold with a thickness of 1 cm.
A columnar sample of X 1 emX 2c+n was obtained.

The alkali resistance of glass was examined as follows.

For each composition of glass, take two samples of Kitazuki, 95
After being immersed in 100 ml of 2N-NaOll aqueous solution for 7 hours at ℃, the weight loss of the sample was measured and the amount of erosion per unit area (mg/cm'') was determined.

The amount of alkali corrosion of the glass obtained in this way is
It is shown in the table and the lower column of Table 2.

As is clear from the results in Tables 1 and 2, the amount of alkali corrosion of the glasses of the present invention (Examples 1 to 10 and Examples 15 to 30) is extremely small, indicating that they exhibit excellent alkali resistance. Incidentally, Examples 11 to 14 in Table 1 are reference examples outside the scope of the present invention.

Comparative Examples A and B Sample glasses were prepared to have the compositions shown in Comparative Examples A and I3 in Table 1, and then their alkali resistance was examined in the same manner as in the Examples.

As is clear from the results in Table 1, the alkali resistance of the glass of the present invention is extremely good compared to Comparative Examples A and B.

f9 Effects of the Invention According to the present invention, as is clear from the examples, a glass having extremely excellent alkali resistance has been realized.

Claims (2)

[Claims] (1) Expressed in mol%, Cr_2O_3 10-25 BaO　0～45 MgO 0~45 P_2O_5 30-60 Huge BaO+MgO 25 or more Alkali-resistant glass characterized by having a composition of (2) In the composition of the glass, 10 mol% or less of Li_2
O, Na_2O, K_2O, CaO, SrO, ZnO,
SnO_2, PbO, MnO, B_2O_3, Al_2
O_3, Fe_2O_3, GeO_2, ZrO_2, T
The alkali-resistant glass according to claim 1, which contains additive components such as iO_2 and La_2O_3, and the total of the additive components does not exceed 15 mol%.