JPH0446037A - Composition for porous glass - Google Patents

Abstract

PURPOSE:To shorten the time necessary for heat treatment and removing by solving and to improve chemical durability by adding specified amts. of ZrO2 and/or SnO2 and P2O5 and/or V2O5 to a specified compsn. consisting essentially of SiO2, Al2O3, B2O3 and R2O (R is Na, K or Li). CONSTITUTION:This compsn. for porous glass is obtd. by adding 1-10wt.% ZrO2 and/or SnO2 and 1-5wt.% P2O5 and/or V2O5 to 50-70wt.% SiO2, 0-5wt.% Al2O3, 20-30wt.% B2O3 and 3-10wt.% one or more among Na2O, K2O and Li2O as essential components. ZrO2 and SnO2 improve the mechanical strength of porous glass as well as the chemical durability but <1wt.% ZrO2 and/or SnO2 does not remarkably produce the effect and >10wt.% ZrO2 and/or SnO2 deteriorates the meltability and moldability of glass and makes the formation of separated phase remarkably difficult. P2O5 and V2O5 are especially effective in forming separated phases but <1wt.% P2O5 and/or V2O5 does not sufficiently act and >5wt.% P2O5 and/or V2O5 deteriorates the chemical durability of porous glass or makes the pores ununiform in diameter.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to porous glass used for separation of gases, liquids, etc., catalysts, carriers for immobilized enzymes, etc., and relates to a porous glass suitable for obtaining the porous glass. The present invention relates to a raw glass composition.

[Prior art and its problems]

By heat-treating 5iOt-(AItos)-BtOs-Nat()-based glass, the phases are separated into a raw Sin system and an 8201-NatO system, and this is immersed in acid etc. to form a B2O.-Na2O system. It is well known that porous glass can be obtained by leaching. However, this porous glass has disadvantages in chemical durability such as water resistance, alkali resistance, acid resistance, etc. There are practical problems such as the need for time and effort to make the pores.

In JP-A-1-145349, Z is further added to the above component system.
It has been disclosed that the chemical durability is improved by incorporating nO and ZrOt, but the introduction of these components makes it difficult to form phase separation, requires a large amount of time for heat treatment, and is difficult to treat with acids, etc. This method is unsatisfactory in that it requires time and effort. Furthermore, Japanese Patent Publication No. 47-29564 discloses that by incorporating PtOs into the component system, phase separation is promoted and heat treatment and subsequent acid treatment can be easily performed. The chemical durability of the component system is poor, and practical problems such as AIPO and system components that are soluble in water etc. precipitate still remain.

The present invention solves these problems, and enables easy melting and vitrification, phase separation formation through heat treatment, leaching with acids, and porosity formation, and the chemical durability of the resulting porous glass, especially alkali resistance. The present invention provides a composition for porous glass that has improved properties.

[Means for solving the problems 1'l1] The present invention has the following properties in terms of weight%: Sin, 50-70, A1 0-5, B
tOs20~30, R103~10 (However, R2O is N
one or more selected from a2O1KtO or Li2O) as the basic component composition, and ZrO2 and/or SnO, 1 to 1Q, P2O. and/or V2O.
It consists of a composition for porous glass containing 1 to 5.

In the present invention, Sin is important as a vitrification component and a skeleton forming component, but if it is less than 50 wt%, melting and vitrification is not easy and devitrification tends to occur. On the other hand, if it exceeds 70 vt%, the melt viscosity increases and melt moldability deteriorates. Therefore, the preferred range is 50 to 70 wt%.

Alx0a is introduced for the purpose of adjusting melt viscosity, improving devitrification resistance, controlling phase separation, etc.
If it exceeds wt%, P80. AIPO reacted.

It produces system components and deteriorates the chemical durability of porous glass, especially water resistance. Alternatively, even if this is leached in an acid treatment process, it is difficult to obtain a porous glass with a uniform bore diameter, and the rate of phase separation is delayed, making it difficult to leach out unnecessary components by Shun etc. Therefore, the amount introduced should be 5 t% or less.

B2O. is opposite to the phase forming the skeleton of the 5ift system,
It is the main component that forms the phase to be taxed by the other acid treatment, and if it is less than 20vt%, the phase separation will be insufficient;
If it exceeds 0 vt%, it will be difficult to obtain porous glass having fine pores with uniform bore diameter, and mechanical strength and chemical durability will deteriorate. That is, it is preferably in the range of 20 to 30 wt%.

10
If it exceeds wt%, the glass fluidity becomes excessive, deteriorating moldability, and devitrification tends to occur. Therefore, the preferred range is 3 to 10 wt%.

As mentioned above, phase separation and formation of porous glass are not extremely easy with these basic components alone, and problems remain in practical terms, such as the chemical durability of porous glass being inferior. Therefore, it is necessary to introduce specific components described below. is extremely important.

ZrO and/or SnO have the effect of improving the chemical durability of porous glass and increasing its mechanical strength, and if it is less than twt%, its effect is not countersignal, whereas if it exceeds 10 ft%, Glass melting and moldability deteriorate. In general, the introduction of these components tends to make it difficult to form phase separation, but if it exceeds 10 wt%, this becomes a countersignature. The preferred range of these components is 1 to 10 vt%.

P□0tsu and/or v20. is particularly effective in forming phase separation in glass, and its effect is insufficient at less than 1 wt%, but it is effectively expressed at tvt% or more; on the other hand, 5w
If it exceeds t%, the above-described formation of AIPO1 generally deteriorates the chemical durability of the porous glass, or the bore diameter becomes non-uniform. Therefore, it should be in the range of 1 to 5 vt%.

The Zr0t and/or SnO, and Plo and/or v2O. The coexistence with the former improves the problems of the former, which makes glass melting difficult and impairs the formation of phase separation, and the former improves the problems of the latter, which deteriorate chemical durability. It has good properties, allows phase separation to occur easily, and subsequent leaching with acids, etc., and bore formation can be easily performed without requiring time or effort.
This has the remarkable effect of significantly improving the chemical durability, especially alkali resistance, and mechanical strength of the resulting porous glass.

[Example 1 The present invention will be explained below based on examples.

Silica sand as a 5iOzJl material, ^l2O. Aluminum hydroxide as raw material, borax as Btus raw material, N&20
, to! Sodium carbonate, potassium carbonate, lithium carbonate, and Zr01s as raw materials for 0, Li, and O, respectively; zircon sand, tin oxide, P2O3, and 2O. Phosphoric acid and vanadium oxide were prepared as raw materials, and these were mixed according to the desired composition.

The mixed raw materials are put into a platinum crucible and heated in an electric furnace.
500℃, 1-5pm Fl! It was melted and cast onto Graffito to obtain a plate glass.

This was further heat-treated in an electric furnace at 600 to 650°C for several tens to hundreds of hours to cause phase separation.

The phase-separated glass sample was crushed and sized to about 0.5 flll + φ, treated in SOA solution for 1s-n at 95℃ for 24 hours, then in 3N-ETSO solution at 95℃ for 24 hours, and then washed with water. A porous glass was obtained by performing an open treatment in a 0.5N NaOH solution at room temperature for 3 hours, washing with water, and drying.

Note that the 3N-H2SO treatment removes ZrO precipitated in the bore.
, colloid removal at 2O. The 5N-NaOH treatment is carried out for the purpose of removing Sin and colloids deposited in the bore.

The bore diameter distribution and surface area of the porous glass were measured using a mercury injection bore sizer model 8310 manufactured by MicroNoritics.

Further, immerse in lN-Na041 solution at room temperature for the required time,
Weight loss was measured.

Table 1 shows the raw glass composition of the main samples among these samples.
Its heat treatment conditions (temperature-time ``C-hr), average bore diameter (person), table iff species (rIi/g), unit time, weight loss per surface area (μg/ci1.hr), and Arrhenius type plot. The rate constant of phase separation was determined by , and the required time rIl (hr) to obtain a bore diameter of 500 at a heat treatment temperature of 600° C. was calculated, and the results are also shown in Table 2.

In the table, Comparative Example 1 has a known raw glass composition of so-called Vycol type, and Comparative Example 2 has Zr01 introduced therein.

As is clear from the table, in the examples according to the present invention, a desired bore diameter can be obtained with a short heat treatment, and the alkali resistance of the porous glass is also extremely excellent.

On the other hand, all of the comparative examples require time for heat treatment, and therefore the leaching treatment with acid etc. also requires time and effort, which is particularly noticeable in comparative example 2. Furthermore, it is clear that Comparative Example 1 is inferior in alkali resistance. Incidentally, the composition of the porous glass in Example 1 was 5% by vt%.
i0274.3, A110jO067, PtOS 6
．． 22, Zr0t 11. Q, axOs 6.20
, Na2O1,81, and in Example 2, Si
O□79.6, has O,94, PtOs
5.58, Zr[11B, 15, B2O. 4.66
, Ha, OG, 9B , K, G O,l , Comparative Example 1
In Sin! 94.3, entered IJs O, 37
, JOs 5. Q, N&! 00.38, and it can be seen that in the examples, Zr0z is concentrated in the porous glass to improve chemical durability such as alkali resistance.

(Hereinafter, Shiratori No. 2 (Table 2, 1℃-hr "in, 'cd/g" ag/d, h
51X 1 person bore I at +5600°C heat treatment time required to obtain r! [Effects of the Invention] According to the present invention, porous glass with a desired bore diameter can be easily obtained by short-time heat treatment and glazing treatment, and it also has excellent chemical durability such as alkali resistance, so it can withstand harsh environmental conditions. It has the effect of being widely usable even under the sun.

Claims (1)

[Claims] 1) SiO_250-70, Al_2O_3 in weight%
0-5, B_2O_320-30, R_2O3-10(
However, R_2O is Na_2O, K_2O or Li_2
(one or more selected from
A composition for porous glass characterized by containing 2O_5 and/or V_2O_51-5.