JPS60264321A - Easily water-soluble powdery alkali silicate composition - Google Patents

Abstract

PURPOSE:An easily water-soluble powdery alkali silicate composition useful as a compounding agent for refractory materials building materials, civil engineering materials, and coating compound materials, easily soluble in water, slightly being set, storable for a long period, obtained by blending ground alkali silicate powder with a solidification inhibitor. CONSTITUTION:Ground alkali silicate powder [having a molar ratio of SiO2/ M2O (M is Na or K) of preferably 2.5-3.0, and the average particle diameter of the raw material alkali silicate powder is ground into 1/3-3/4] is blended with 7-10wt% based on the ground alkali silicate powder of a solidification inhibitor (one or more selected from clay minerals, water-insoluble metal oxide, metal hydroxide, metal carbonate, and glass cullet having 0.5-30mu average particle diameter), to give the desired easily water-soluble powdery alkali silicate composition.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an easily water-soluble powdered alkali silicate composition useful as a compounding agent for fireproof materials and construction, civil engineering, and coating materials. The present invention relates to a powdered alkali silicate composition which is obtained by blending an anti-caking agent with crushed alkali powdered silicate, and which is easily dissolved in water, hardly caking, and can be stored for a long period of time.

[Prior Art] As is well known, powdered alkali silicate is used as a binder by blending with fire-resistant materials such as alumina and magnesia, and is also blended into cement products or mixed at construction sites for construction, civil engineering, and other applications. Used as a coating material, anti-breathing agent for cement milk, mortar, and concrete.
It is used in a wide range of fields because it has the effects of an quick-setting agent, an alkaline stimulant, and a neutralization prevention agent.

Such conventional products generally referred to as powdered alkali silicate are manufactured by spray drying an aqueous alkali silicate solution. This powder has a particle size of 2 as shown in Figures 7 and 8.
It has a hollow spherical shape of 0 to 300 u, and the part corresponding to the shell of the sphere is an alkali silicate of rotten wood, which dissolves in water to become an aqueous aqueous alkali silicate solution.

Table 1 shows examples of the ingredients of powdered sodium silicate currently on the market.

Table 1 [Problems to be Solved by the Present Invention] However, when a conventional compound containing a powdered alkali silicate is kneaded with water, the dissolution of the powdered alkali silicate is insufficient, resulting in a molded product. Performance such as lack of strength -
There were problems that tended to cause shortcomings.

The reason for this is that the powdered alkali silicate particles are spherical, which minimizes the surface area and slows down the dissolution rate. Also, the hollow part is not completely sealed and water can enter the hollow part through the bores and cracks in the shell.
When kneading a powdered alkali silicate compound with water to create a fluid slurry, a large amount of water is required to account for the water trapped in the hollow part, which reduces the strength of the compact and requires extra water for drying. energy is required.

Further, after the moisture contained in the hollow body is released by drying, pores remain in the molded body. Furthermore, air remaining in the hollow portion without being replaced by water and air bubbles expelled by the replacement also form pores in the molded body. As a result, the molded body becomes porous, resulting in defects such as reduced strength.

Particularly, when such a powdered alkali silicate is used as a paint vehicle, bubbles are a fatal defect.

[Means for Solving the Problems] As a result of research conducted in view of such conventional techniques, the present inventors have found that by crushing the conventional powdered alkali silicate to destroy its spherical particle structure, it has been found that it can be easily water-soluble. This powder form has the properties of making it more flexible and eliminating the trapping of water in hollow parts, and preventing caking caused by densification due to crushing by adding an anti-caking agent to the crushed alkali silicate powder. The present invention was completed by discovering that an alkali silicate composition can be obtained.

That is, the present invention is an easily water-soluble powdered alkali silicate composition comprising crushed powdered alkali silicate and an anticaking agent.

The crushed alkali powder silicate in the present invention is a powder obtained by crushing the alkali powder silicate of raw material 1, and as the alkali silicate, common and inexpensive sodium silicate and potassium silicate are used.

The crushed alkali silicate powder may be crushed to such an extent that the spherical particle structure of the alkali raw material powdered silicate is destroyed and the original hollow spherical shape is not maintained, and preferably the number of particles of the alkali raw material powdered silicate is 50. % or more are crushed, and in terms of the average particle size, it is preferable that the average particle size is 1/3 to 3/4 of the average particle size of the raw material alkali silicate powder.

To give a specific example, the shape and particle size of the powdered alkali silicate before crushing are not particularly limited, but are generally 20 to 300
Consists of JL hollow spherical particles with an average diameter of 50 to 1
It is about 50 u, and the shell thickness is about 5 to 1011 degrees. The preferable average diameter of the powdered alkali silicate after crushing is about 20 to 707 L, and is further limited to about 40 to 50 IL in order to maintain constant quality. Of course, further crushing will increase the fracture surface and will speed up the dissolution, but excessive crushing will unnecessarily increase the crushing cost and cause other drawbacks such as the generation of powder dust, so the above range is preferable.

Next, the crushed state of the crushed powder alkali silicate in the present invention will be explained using electron micrographs (magnification: 100x) shown in Figures 1 to 8. The fine particles of powdered sodium silicate are hidden under the large particles and are difficult to see, but they are particles with an average particle size of 20 to 300 pL (average particle diameter 'i'oJ1.).

Figure 1 shows the particles crushed using a vibration mill, and the average particle size is 44.
In IL, some fine particles remain uncrushed, but most of the large particles are crushed. Original average particle diameter = 0.83.

0 Figure 2 shows the result of crushing with a ball mill, and the average particle size is 41 #L, and the original average particle size is 0.5.
There are 0 in 9.

Figures 3 to 6 show particles crushed using a pulverizer (method of Example 1), each with an average particle size of 51 l (Figure 3).
, 43IL (Figure 4), 33IL (Figure j5),
25JL (FIG. 6), and are respectively 0.73, 0.61, 0.47, and 0.38 of the original average particle diameter.

In this case, most of the 51 l (0.73) particles maintain their spherical shape (uncrushed), but the crushing effect is not sufficient, but they can be used satisfactorily depending on the purpose.

Therefore, various types of crushers can be used for crushing, but the particle size of the crushed product is preferably 374 (0.75) or less of the original average particle size.

Furthermore, in the case of 25 IL (0,3B), almost all particles are crushed, and the diameter of the crushed product does not need to be smaller than 1/3 (o, a3) of the original average particle diameter.

Since the crushed powder alkali silicate in the present invention becomes fine by crushing and increases its solubility in water, its molar ratio Sing/M20 (M indicates Ha or K) is not particularly limited to the grade. Although a low molar ratio to a high molar ratio can be used, it is preferable that the molar ratio is in the range of 2.5 to 3.0. The reason for this is that if it is less than 2.5, the alkali content will increase, making it uneconomical as the amount of hardening agent used for gelling and curing will increase, and the fire resistance will decrease in fireproof materials applications, and in construction materials applications. This is because only a product with poor water resistance can be obtained, causing efflorescence, and if it exceeds 3.0, the dissolution rate may be extremely reduced, which may be undesirable.

To prepare the molar ratio of the crushed alkali powder silicate in the range of 2.5 to 3.0, a powder alkali silicate obtained by spray drying an aqueous alkali silicate solution with a molar ratio of 2.5 to 3.0 can be used. However, a low molar ratio and a high molar ratio of powdered alkali silicate may be mixed to obtain a molar ratio of 2.5 to 3.0. In this case, as an alkali silicate with a low molar ratio, the molar ratio is 2, which has a fast dissolution rate.
．． 0 to 2.7 can be used. The molar ratio is 2.7 to 3.3, which has a low alkaline content as a high molar alkali silicate.
can be used. In this case, a high molar ratio alkali silicate, which has poor solubility when used alone, has improved solubility when used in combination with a low molar ratio alkali silicate, and the dissolution tends to be faster than when the alkali silicate is not mixed at the same molar ratio. This is considered to be because the alkali produced by first dissolving the alkali silicate with a low molar ratio promotes the dissolution of the alkali silicate with a high molar ratio.

In the present invention, since the anti-caking agent is used for the purpose of preventing caking of the crushed powdered alkali silicate, any fine powder that does not have reactivity with the alkali silicate can be used, and the preferred anti-caking agent is Specific examples include clay minerals such as talc, kaolin, and mica, water-insoluble metal oxides, metal hydroxides, and metal carbonates, such as ZrO2,5
iOz, Alz03, ZnO, TiO2, Zr(O
H)4. Examples include one or more selected from An (OH)3, CaCO3, etc., and glass cullet. Particularly preferred among these are tabular metal oxides or hydroxides, such as tabular ^X, 03, or An(OH)3.

The particle size of the anti-caking agent is not particularly limited when the anti-caking agent is crushed and used together with the raw material powdered alkali silicate, as long as it becomes fine at the same time, but it can be mixed with the crushed powdered alkali silicate. If so, the average particle size is 0.5 to 3.
A particle size of 0IL is preferable; if it is less than 0.5L, the amount of hydric acid required for wetting the powder increases, and the amount of water required for turning the powdered alkali silicate compound into a slurry increases. If it exceeds 0, the effect on consolidation prevention 1 will decrease, which is not preferable.

The anti-caking agent II may have a spherical particle shape, but plate-like particles are preferable because they have a greater anti-caking effect.

Moreover, porous particles are undesirable because they increase the amount of water.

The easily water-soluble powdered alkali silicate composition of the present invention is a composition consisting of the crushed powdered alkali silicate described in -h and an anti-caking agent, and includes the crushed powdered alkali silicate prepared to a specific particle size and an anti-caking agent. It can be easily obtained by blending a powdered alkali silicate with an anti-caking agent, or by mixing an anti-caking agent with raw material alkali silicate powder and crushing the mixture to obtain a specific particle size.

The proportion of the anti-caking agent in the composition of the present invention is desirably 5 to 15% by weight, preferably 7 to 10% by weight, based on the crushed alkali powder silicate, and less than 5% by weight prevents caking. The effect is low, and even if the amount exceeds 15% by weight, no increase in the effect is observed and it is uneconomical.

1,,... [fl" m+ The crushed alkali powder silicate in the present invention is composed of fine, hollow spherical particles with exposed inner surfaces, which are obtained by crushing the raw material alkali powder silicate. Solubility increases.For example, by simply dividing one particle into two, the hollow inner surface is exposed to the surface, so the effective surface area for dissolution is more than doubled, and dissolution becomes faster.

Furthermore, the water content is slightly different between the outer surface and the inner surface of the membrane, and the inner surface has slightly more water than the inner surface, and the exposure of the inner surface, which has better solubility, also accelerates dissolution.

In addition, since the hollow spherical particles of the powdered alkali silicate used as the raw material are destroyed, water is not trapped in the hollow part, which reduces the amount of water required for turning into slurry, and also keeps air inside the spheres within the slurry. The molded product does not contain any air bubbles and becomes dense. Furthermore, since the easily water-soluble powdered alkali silicate composition of the present invention contains an anti-caking agent, it is possible to prevent the crushed powdered alkali silicate from caking due to densification.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples 2. I will clarify. Note that % is weight %.

Examples 1 and 2 and Comparative Example 1.2 Powdered sodium silicate No. 2 50K having the composition shown in Table 1
g (average particle size 90Jj,), powdered sodium silicate No. 3 5
0 kg (average particle size 130 IL) and 11.1 kg (average particle size 50 pL) of dry aluminum hydroxide (manufactured by Kuchiki Light Metal) were mixed thoroughly using a 300-piece V-type mixer, and this was designated as sample 3. ), Hosokawa ACM-10
It was crushed using a mold crusher (manufactured by Honkawa Micron ■) to obtain a crushed product weighing about 100 kg. This one has an average particle size of 43
According to microscopic observation, more than 50% of the powdered sodium silicate particles were destroyed, and almost 100% of the dry aluminum hydroxide was finely crushed to 20 pieces or less. Also, the chemical analysis value of this product is 5iOQ = 51.34%, N
a20 = 18.53%, (SiO2/Na2O) molar ratio = 2.88, An (OH)3 = 10.27
%Met. This is designated as sample 1.

Separately, an aqueous sodium silicate solution with a molar ratio of 2.80 was prepared, and this was spray-dried to produce powdered sodium silicate with a molar ratio of 2.80, and AJII (OH)3 was mixed therein. This will be referred to as 3 Sample 4. Crush in the same manner as above to obtain an average particle size of 43I.
A powdered sodium silicate containing 10% of L (0)1)3 was obtained. This is designated as sample 2. Sample 1 (
Example 1), Sample 2 (Example 2), Sample 3 as a comparative example
(Comparative Example 1) and Sample 4 (Comparative Example 2) 20g of each sample of the powdered sodium silicate composition was dissolved in 50mM water at 10°C under stirring, and from the relationship between the dissolution time and the dissolution rate, the dissolution rate was determined. When measured, the characteristics shown in the graph of FIG. 9 were obtained. In this way, 50% of sample 1 dissolved in about 3 minutes, and sample 2 dissolved.
Approximately 25% of the amount was dissolved in 3 minutes. It is observed that the dissolution is extremely fast compared to sample 3.4.

Test Example 1 An example is shown in which Samples 1 to 4 manufactured in Example 1.2 and Comparative Example 1.2 were used as a binder in a refractory. Sintered alumina was used as the aggregate in the proportions shown in Table 2. 80g of each of samples 1 to 4 was added to 3000g of the sintered alumina, and 15g of sodium silicofluoride was added, mixed thoroughly, and then poured into 10°C water. 270 g was added and kneaded using a Hobart mixer. Sample 1 of the example of the present invention became a slurry in 24 minutes, sample 2 became a slurry in 3 minutes, but the sample of the comparative example
3 and 4 required more than 5 minutes to turn into a slurry.

Next, determine the minimum amount of water (10℃) that can make each sample into a slurry by kneading for 3 minutes, and use this amount of water to
A molded body was made using the method of 553 (Refractory Testing Method) and a strength test was conducted. For curing, airtight curing is performed at 10℃ at 1 F1.
I did it. Further, drying was carried out at 110° C. for 16 hours, baking was carried out at each temperature shown in Table 3 for 3 hours, and a strength test was conducted after cooling. The results are shown in Table 3.

Table 2 5 Table 3 6 As shown in Table 3, the product of the present invention can be molded with a low amount of water;
The strength test data was also high.

Example 3 and Comparative Example 3 Powdered Sodium Silicate No. 2 100 having the composition shown in Table 1
Kg (average particle size 80IL), powdered sodium silicate No. 3 1
22
．． 2Kg was placed in a 5001 ball mill (silica stone lined, using silica poles) and crushed for 3 hours until the average particle size was 41p.
A crushed product with a molar ratio of 2.8 was obtained. This is sample 5 (
Example 3) As a comparative example, a mixture of the same composition but only mixed without crushing was prepared and designated as Trial 116 (Comparative Example 3).

From the relationship between the dissolution time and the dissolution rate when 200 g of each sample of the powdered sodium silicate composition of sample 5 and the powdered sodium silicate composition of sample 6 was dissolved in 300 mJl of water at 2 ° C. with a stirrer, 2
Measure the dissolution rate in cold water kept at ℃ and use the results as the first
It is shown in the graph of Figure 0. It is observed that Sample 5 of the Example of the present invention exhibits better solubility than Sample 6 of the Comparative Example.

7 Test Example 2 An example will be shown in which Sample 5 (Example 3) and Sample 6 (Comparative Example 3) manufactured in Example 3 and Comparative Example 3 were used as cement admixtures.

Add samples 5 and 6 to 1000 g of Portland cement l-20
A cement composition was prepared by adding and mixing 0 g. This was added to 800 g of 10'0 water and stirred for 5 minutes to form a slurry. This slurry is 40 in diameter x 80+ in height.
It was poured into an SM mold and allowed to stand and harden. A homogeneous hardened product was obtained from the cement composition using Sample 5, but a homogeneous hardened product was not obtained from Sample 6 because 4III became porous with air bubbles from the upper surface.

Example 4 and Test Example 3 (20 to S+02 +) Solids content 79%, (Si02 /
20) 100Kg of powdered potassium silicate (average particle size: 0IL) having a composition with a molar ratio of 3.0 and 11Kg of dry aluminum hydroxide (manufactured by Nippon Light Metal) were thoroughly mixed using a 300mm Q-type mixer. A portion was taken and designated as sample 8. The remaining mixture was placed in a ball mill and crushed for 3 hours to obtain a crushed product with an average particle size of 40 hiro. This is designated as sample 7.

Both sample 7 and sample 8 have compositions (20
) Solid content 71.1%, (Si02/20) molar ratio 3.
0, AKL(OH)3 L9%.

An example is shown in which Sample 7 (Example 4) and Sample 8 (Comparative Example 4) are used as vehicles for an inorganic fireproof coating material.

80g each of sample 7 or 8, 8g of sodium silicofluoride,
After thoroughly mixing 1000g of aggregate with the composition shown in Table 4,
After adding 270 g of water and mixing for 3 minutes, the mixture was coated on an iron plate to a thickness of 2 cm and immediately dried at 110° C. for 16 hours. The coated surface using sample 7 was smooth, but the coated surface using sample 8 had crater-like marks formed by the removal of air bubbles, and no smooth surface was obtained.

(j::” 9 Table 4 Examples 5-7 and Comparative Examples 4-6 An example of the effect of anti-caking+L agent will be shown.

Powdered Sodium Silicate No. 2 50Kg having the composition shown in Table 1
(Average particle size 90g), Powdered Sodium Silicate No. 3 50Kg
(Average particle size 13 (for l) was thoroughly mixed using a 300 cross type mixer. This is referred to as sample 9. Sample 9 was crushed in the same manner as in Example 1, and a crushed product with an average particle size of 44 mm was obtained. This is designated as sample IO.

Separately, dried aluminum hydroxide was crushed to obtain five kinds of crushed products.

A caking test was conducted by adding and mixing various amounts of dried crushed aluminum hydroxide as an anti-caking agent to sample IO. Separately, calcium silicate glass powder with an average particle size of 40#L was added as an anti-caking agent. The test results are shown in Table 5.

0 Table 5 m: 72 In the test, 100g of each sample was divided into 100 x 10hm
sealed in a plastic bag (double layered) and loaded with 25 kg.
The hardness was examined after being allowed to stand at 711°C in an atmosphere.

Reference example Case 1 of curing powdered sodium silicate with sodium silicate fluoride An example of the influence of the molar ratio of powdered sodium silicate in the composition is shown below.

An aggregate was prepared by mixing 70 g of No. 5 silica sand and 30 g of silica fine powder (trade name: 1 clay, manufactured by Marueju Goki Company). Aggregate 1
Powdered sodium silicate crushed to 00g (average particle size 40-4
5#L) 3g, Sodium silicofluoride (Na2
SiFc) lg was added and thoroughly mixed, water necessary for turning into a slurry was added, kneaded for 3 minutes, and the mixture was poured into a mold with a diameter of 30 m and a height of 5 m and sealed with a lid. This uncured material is 1
Let stand in an atmosphere of 0°C or 20°C for 24 hours to harden,
It was extracted from the mold, dried at 110°C for 16 hours, and then subjected to a strength test. In addition, a portion of the kneaded material was collected in a plastic bag and sealed, allowed to stand at the same temperature, and occasionally pressed with a finger to measure the time until hardening. The measurement results are shown in Table 6, and the molar ratio is 2.4.
Below, the curing time is long at 10°C, and it takes half a day to judge the effectiveness of the application, which is not practical. Moreover, if the molar ratio is larger than 3.0, the dry strength is low and it is not practical.

2 Table 6 11: [3 [Effects of the Invention] Since the powdered alkali silicate composition of the present invention is a fine powder with a crushed spherical particle structure, it is easily water-soluble and prevents caking due to densification. 11, it dissolves faster than conventional powdered alkali silicate and is useful for various uses as shown below.

When used as a refractory binder, for example, when kneading with water is carried out in a short time, such as with basic spray castable, the amount of kneading water can be reduced by using the product of the present invention, increasing the strength of the constructed body, Reduce energy loss due to water evaporation.

In addition, even acidic and neutral castables become slurry-like in a short period of time, so water can be mixed accurately, eliminating the need to use excess water and making cleaning easier.

When used as a cement admixture or grouting agent, it becomes possible to use cold water for construction, making it easier to perform work in cold regions, which has traditionally been a problem. Even in environments where commercially available alkaline silicate aqueous solutions have a viscosity of 4.1" and almost lose fluidity at low temperatures, making them difficult to use, when the product of the present invention is dissolved and used, heat of dissolution is generated due to rapid dissolution. A sufficiently fluid aqueous solution can be obtained by sealing at a liquid temperature. A similar effect can also be achieved when the powder is mixed with cement in advance.

Even when powdered alkali silicate is blended into cement products or mixed at the construction site, the use of the product of the present invention ensures stable construction without any strength defects or built-in air bubbles due to undissolved components. be able to. Similarly, as a vehicle for inorganic paint, it does not generate bubbles and can be applied without defects.

[Brief explanation of drawings]

FIGS. 1 to 6 are electron micrographs showing the particle structure of crushed powdered sodium silicate according to the present invention, and FIGS. 7 and 8 are electron micrographs showing the particle structure of conventional powdered sodium silicate before crushing. Micrographs, Figure 9 are from test 41 to test 1I4.
Graph 5 showing the dissolution speed of Sample No. 4 and FIG. 10 are graphs showing the dissolution speed of Sample No. 45 and Sample 6. Applicant Nihon Kagaku Kogyo Co., Ltd. Agent Yutaka 1) Yoshio 6 Figure 1 (x 100) Figure 3 (x 10o) Figure 9 8 minutes (minutes)

Claims (1)

[Claims] l) An easily water-soluble powdered alkali silicate &+ composition comprising crushed powdered alkali silicate and an anti-caking agent. 2) Crushed powdered alkali silicate has a molar ratio of 5i02/M2
0 (M represents Na or K) 2.5 to 3.0 and is obtained by crushing the average particle diameter of the raw material powder alkali silicate to 1/3 to 3/4. Easily water-soluble powdered alkali silicate composition. 3) The anti-caking agent has an average particle size of 0.5 to 30μ, respectively.
Claims 1 or 2 are one or more selected from clay minerals, water-insoluble metal oxides, metal hydroxides, metal carbonates, and glass cullet. Easily water-soluble powdered alkali silicate composition. 4) 5 to 15% by weight based on crushed alkali powder silicate
An easily water-soluble powdery alkali silicate composition according to any one of claims 1 to 3, comprising an anti-caking agent.