JPS6121943A - Curing agent - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a curing agent for alkali silicate salts.

Alkaline silicates are widely used as binders, adhesives, surface treatment agents, etc. in the fields of paints, refractories, and building materials, and sodium silicate has long been used as a hardening agent.

However, due to recent increased interest in environmental issues, it has become a problem that this sodium silicate fluoride is a deleterious substance and that fluorine gas is generated due to heating, so various hardening agents have been developed to replace it. has been considered.

The conditions required for alkali silicate as a hardening agent are as follows:
These include curing speed, strength of the cured product, heat resistance, water resistance, acid resistance, little expansion and contraction of the cured product, and no migration of the binder.

By the way, the examples that have been considered so far are:
Condensed aluminum phosphate relatively satisfies these conditions, and is particularly suitable for solutions consisting of organic acid ions, phosphate ions, and aluminum ions, or organic acids and phosphorus ions, as seen in Japanese Patent Publication No. 57-7587. A dried suspension of one or more of acid, metallic aluminum, aluminum oxide, and aluminum hydroxide, or a fired product of this dried product, exhibits excellent hardening properties. .

However, such curing agents require the use of expensive raw materials, drying of the solution or suspension, and further calcination of the drying product to obtain more favorable curing properties. It cannot be used as a substitute for inexpensive hardening agents such as sodium silicofluoride, which has to be expensive.

On the other hand, soluble phosphorus or calcined phosphorus are known as inexpensive hardening agents for water glass, but because they are fired at high temperatures, the reaction is slower than that of alkali silicate. It is not necessarily appropriate. Further, heavy superphosphate lime is also known as a hardening agent, but the hardening reaction is too fast and it is difficult to secure sufficient working time, so its use is naturally limited.

Therefore, the present inventors have repeatedly searched and researched an inexpensive water glass hardening agent that can be substituted for sodium silicofluoride. As a result, the by-product phosphorous fertilizer, which is produced at low cost as a fertilizer, has been found to be a substitute for the condensed phosphates. In comparison, it was found that although the water resistance was slightly inferior, it exhibited considerably good curing characteristics, and the present invention was completed based on this finding.

The by-product phosphorus used in the present invention is a by-product when refining a wet phosphoric acid solution.
Soda ash and lime were added to form a precipitate, and this precipitate was dried and pulverized with the addition of some phosphoric acid solution. Regarding the composition of this by-product phosphorous fertilizer, CaHPO
t, Ca(H,PO,),.

Cab(Pot)+, FePot, k
lPol, NaH+P Ot , OaF+ , Ca
5 (Pot) F8 etc. are estimated to be included.
Although it is not clear how these compositions act on the alkali silicate salts to harden water glass, the main compositions that perform the hardening action are caHpo, , aa (HtPO
i)z, Cab(POi)+, and other compositions are considered to play an auxiliary function to curing. Of course, the conjugation function between these compositions cannot be ignored.

The curing properties of the curing agent of the present invention are that when commercially available by-product phosphorus is used as it is, curing is slightly faster, but when used after washing with water, curing is slower.

Therefore, the curing time can be adjusted by the degree of washing with water, and the curing time can also be adjusted by the amount added, as with a normal curing agent. Furthermore, the curing time can also be adjusted by pulverizing commercially available by-product phosphorus and adjusting its particle size. In general,
The finer the powder, the faster the curing time. The ratio of the curing agent of the present invention to the alkali silicate salt will now be explained using the case of refractories as an example.

(Specific example) 100 parts by weight (hereinafter referred to as "parts") of waxite aggregate having the particle size composition shown in Table 1 below, and 3 parts by weight of liquid.
No. water glass (Si0.28.6%, Na+096%) 2
Add 0 parts of the curing agent of the present invention (particle size 200 mesh pass)
An unwashed product and a washed product were added in the proportions shown in Table 2, and the curing time was measured.

The results are shown in Table 2.

Incidentally, the above-mentioned water-washed product refers to a product that is batch-mixed with twice the amount of water for about 1 hour and dried by p.

Table 1 Table 2 * This is the time from when the specimen is placed in a 30°C (7) thermostat until the fluidity disappears when the specimen is pressed with fingers.

As is clear from the table above and the above, the curing time of the curing agent of the present invention differs depending on whether it is washed with water or not. Adding more than 30% by weight (hereinafter "%" means "weight%") to No. 3 water glass is undesirable because the strength of the cured product, film strength, or adhesive strength will weaken.
% or less, a sufficient curing function cannot be achieved.

As mentioned above, the curing agent of the present invention does not have sufficient water resistance when used alone. Therefore, as a result of further research in order to improve the water resistance, it was found that when this and boric acid were used together, the water resistance was significantly improved. The proportion of boric acid used in such cases varies depending on the desired water resistance, but is preferably 10% or less based on liquid filter No. 1 water glass.

If it exceeds 10%, the reaction between the curing agent and water glass will be too rapid, making it impossible to ensure sufficient workability.

The present invention will be further explained below with reference to Examples.

Example 1 20 parts of liquid No. 5 water glass was added to 5100 parts of the wax shown in Table 1.
1 part, 8 parts water and 5 parts by-product phosphorous fertilizer (200 meters), and 3 parts of the same phosphorus fertilizer washed with the same amount of water, separated by F using a centrifuge, and dried. ,
The remaining ingredients were added in the same proportions as above, and after kneading them separately and uniformly, 20 x 20 x 80
The mold was poured into one mm mold, and after 24 hours at 50''C, the mold was removed, and the strength of the dough bending and compression of the dough was measured.1.The appearance condition was also observed.

Also, for comparison, calcined phosphorous fertilizer (200 metsushiyuhas)
Six parts of each of the molten manure (200 Metsushipanu) were kneaded, poured, and demolded in the same manner as in the above-mentioned examples of the present invention, and then the same measurements and observations were carried out.

The results are shown in Table 6.

Example 2 To 100 parts of liquid No. 3 water glass, 40 parts of silica powder, 10 parts of bentonite, and 15 parts of phosphorus by-product of washing in Example 1t were added (invention example of Sui-Tei 1), and , 11 parts of the same phosphorous fertilizer and 4 parts of boric acid powder, a total of 15 parts, and the remainder were added in the same proportions as above (Invention example of Sui-Tei 2)
After kneading them separately and uniformly, they were troweled onto a slate board, and a calcium silicate-based heat insulating board with an apparent specific gravity of 02 was adhered. After drying these at 110° C., they were immersed in water for 8 days, and the adhesion state was examined, and the decrease in electrical storage of the dried products before and after immersion was measured.

The results are shown in Table 4. 4 Example 6 To 100 parts of natural No. 6 silica sand, 10 parts of No. 3 water glass and 2 parts of unwashed by-product phosphorus used in Example 1 were added,
(Includes the invention example of Sui-Tei 1, and adds 0.5 parts of boric acid to 50 parts of wet cake (water content 42%) obtained by adding the same amount of water to the same phosphorous fertilizer and batch mixing, and separating the phosphorus fertilizer solids by P. 2 parts of the curing agent obtained by drying and pulverizing and the rest were added in the same proportions as above (invention example of Mizui 2) were homogeneously kneaded, and then SO*
Place it in a molding tube, remove it after 5 strokes with a rammer, and make 3 parts at 0°.
C (7) The molded body was placed in a thermostatic chamber and taken out at predetermined time intervals, and the change in compressive strength of the molded body over time was measured.

The results are shown in Table 5.

Table 5 Example 4 50 parts of natural No. 6 silica sand and silica powder (600 pieces)
To 50 parts, 20 parts of liquid No. 5 water glass and 4 parts of unwashed by-product phosphorus used in Example 1 were added (Sui-Tei 1
Example of the invention), and a total of 4 parts of the above-mentioned 4 parts of compost, 2 parts of compost, and 2 parts of Bic acid powder, and the rest in the same ratio. The added items (example of the invention of Mizuo 2) are each separated into 20 x 20 x 80 m
The shrinkage rate of each cured product was measured using calipers after 24 hours had elapsed. 1. Next, the cured product was heated to 500°C.
After time heat treatment, the bending strength was determined to be 65% HC/
The flexural strength and weight change rate of the dried specimens were examined by immersing the specimens in 100% water at room temperature for 24 hours and then drying them.

The results are shown in Table 6.

X+OO-

Claims (1)

[Scope of Claims] 1. A curing agent for alkali silicate consisting of by-product phosphorus. 2. Hardening agent for alkali silicate consisting of by-product phosphorus and boric acid.