JPH021109B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a curing agent for alkali silicate. More specifically, the present invention relates to a novel curing agent for alkali silicate containing an amorphous alkali calcium silicate as an active ingredient. Conventionally, inorganic acids,
Many substances such as silicofluorides, phosphates, metals, metal oxides, metal salts, and organic compounds have been proposed, and among these, sodium silicofluoride, condensed phosphates, calcium silicates, etc. Widely used. However, there are concerns about pollution problems during the firing process due to the large amount of fluorine contained in sodium silicate, and although condensed phosphates have excellent strength at high temperatures of 1000℃ or higher, It has the drawbacks of insufficient strength and high cost. On the _other hand, calcium silicates are widely used because they _are inexpensive, and crystalline calcium silicates (specially Publication No. 49-11866, Japanese Patent Publication No. 55-36626, Japanese Patent Application Publication No. 32358-1982, Japanese Patent Publication No. 77064-1977, Japanese Patent Publication No. 1987-770-
175768), amorphous calcium silicates such as granulated blast furnace slag, fly ash, etc.
(Japanese Patent Publication No. 57-77062), ordinary Portland cement, alumina cement, or silicate slag discharged from various metal smelting processes (Japanese Patent Publication No. 56-21748)
can be mentioned. However, all of these alkali silicate curing agents made of calcium silicates have the following various drawbacks. (1) Because the reaction with alkali silicate is either very sensitive or slow, setting an appropriate curing time requires delicate adjustment of the amount of curing agent used, or It is necessary to add auxiliary agents such as accelerators or curing retarders. (2) Curing time is significantly delayed at low temperatures compared to room temperature, and changes in the amount of curing agent added tend to greatly affect properties such as strength of the cured product. (3) Many have poor water resistance, acid resistance, efflorescence resistance, and dimensional properties after drying and heating. (4) Dusting is likely to occur due to volumetric expansion at high temperatures. The present inventors have improved the above-mentioned drawbacks, and have achieved excellent workability in setting the curing time and its reproducibility as a room-temperature curing agent for alkali silicate, and improved the strength and water resistance of the cured product after drying and heating. As a result of intensive research into calcium silicate hardening agents that have excellent properties such as acid resistance, we discovered that hardening agents containing amorphous calcium silicate alkali as an active ingredient are extremely superior.
The invention has been completed. That is, the present invention is a curing agent for alkali silicate characterized by containing an amorphous alkali calcium silicate as an active ingredient. The present invention will be explained in detail below. The amorphous calcium silicate alkali according to the present invention has a molar ratio of CaO (or CaO + MgO)/SiO ₂ of 1.8.
and CaO (or CaO + MgO) 10-65% by weight, SiO ₂ 15-75% by weight, M ₂ O (M represents an alkali metal) 0.5-20% by weight, Al ₂ O ₃ (or Al ₂ O ₃ +
Fe ₂ O ₃ ) 1-10% by weight, F1-7% by weight, P ₂ O ₅ 0-
Preference is given to those having a composition of 16% by weight. M of M ₂ O in the above composition represents an alkali metal,
Among these, sodium and/or potassium are particularly preferred. Specifically, as the amorphous calcium silicate alkali according to the present invention, amorphous calcium sodium silicate and/or amorphous calcium potassium silicate are preferable. In addition, an appropriate amount of M ₂ O is 0.5 to 20% by weight; if it exceeds 20% by weight, it will be difficult to make it amorphous, and if it is less than 0.5% by weight, the curing time of the alkali silicate will be significantly longer, and its performance as a curing agent will deteriorate. It's not appropriate. The molar ratio of CaO (or CaO + MgO)/SiO ₂ of the amorphous calcium silicate alkali according to the present invention is 1.8
Below, it is preferably 0.4 to 1.8; if it exceeds 1.8, it becomes difficult to make it amorphous, and the product tends to have an amorphous ratio of less than 40%, making it difficult to fully demonstrate its effectiveness as a curing agent. Further, when the molar ratio is less than 0.4, there is no particular problem as a curing agent, but in some cases, the viscosity of the amorphous melt increases, making it difficult to manufacture. 1 to 10 Al ₂ O ₃ (or Al ₂ O ₃ + Fe ₂ O ₃ ) in the structure
It is appropriate to include the amount in the range of % by weight because the amorphous melting point will be low, and outside this range, the melting point will be high and it is not preferable in terms of production. F works to lower the amorphization melting point, and is preferably contained in the composition in an amount of 1 to 7% by weight.If it exceeds 7% by weight, amorphization becomes difficult due to crystal precipitation of _CaF2 , etc. If it is less than %, the effect as a melting point depressant cannot be obtained. The above composition may contain 0 to 16% by weight _{of P2O5} . P ₂ O ₅ , as an amorphous component of a hardened alkali silicate, has excellent effects on strength, water resistance, etc. after heating and firing, but if the content exceeds 16% by weight, it is difficult to make it amorphous. At the same time, the curing time is significantly delayed, which is not preferable. The amorphous alkali amorphous calcium silicate according to the present invention refers to one that shows an amorphous pattern in an X-ray powder diffraction diagram, and the amorphous rate is defined by the following formula. say. Y=(1-A/B)×100 Y: Amorphous rate (%) A: Strongest line length of calcium silicate diffraction line at diffraction angle 2θ=25~35° B: 2 at 950℃ Strongest line length of calcium silicate diffraction line at diffraction angle 2θ = 25 to 35° when subjected to crystallization operation by slow cooling after heating for a time The conversion rate is practically 40% or more, preferably
A content of 50% or more is suitable; if the content is less than 40%, the curing time of the alkali silicate becomes relatively long, so it is necessary to increase the amount of the alkali silicate, which is economically disadvantageous. An example of the method for producing amorphous calcium silicate alkali according to the present invention includes CaO raw materials such as quicklime, slaked lime, limestone, and dolomite, _SiO2 raw materials such as silica sand, silica stone, and calcium silicate, soda carbonate, potassium carbonate, Na ₂ O, K ₂ O raw materials such as caustic soda and caustic potash, aluminum hydroxide, alumina, alumina sand,
Al ₂ O ₃ raw materials such as cryolite, F raw materials such as fluorite, sodium fluoride, and sodium silicofluoride, and P ₂ O ₅ raw materials such as phosphate rock are blended to obtain the desired chemical composition. ℃
It can be obtained by heating and dissolving the mixture and then rapidly cooling it with water or air. Further, the particle size of the amorphous calcium silicate alkali according to the present invention is not particularly limited as long as it can be used as a curing agent for alkali silicate in general, but preferably 100 mesh pass 100
%, 325 mesh pass 50-100% is appropriate. The alkali silicate to which the alkali silicate curing agent containing amorphous alkali calcium silicate as an active ingredient according to the present invention can be applied include sodium silicate No. 1, No. 2, and No. 3 specified in JIS K 1408;
An aqueous aqueous alkali silicate solution having a SiO ₂ /Na ₂ O molar ratio of 3 or more, such as high molar ratio sodium silicate, potassium silicate, lithium silicate, etc., is used. Further, powdered sodium silicate and powdered potassium silicate having a moisture content of 10 to 30% by weight can be premixed with the curing agent for alkali silicate according to the present invention, and can be used more advantageously. The amount of the curing agent for alkali silicate of the present invention added to the alkali silicate can be varied depending on the solid concentration of the alkali silicate used, the desired curing time, etc., and does not need to be particularly limited. , usually alkali silicate solid content
It is preferred to use 1 to 250 parts by weight per 100 parts by weight. Even if more than 250 parts by weight is used, no improvement in the properties of the resulting cured product can be expected, resulting in an economic disadvantage, and if it is less than 1 part by weight, the effect as a curing agent cannot be fully exhibited. In the present invention, the action mechanism of amorphous calcium alkali silicate as a curing agent for alkali silicate is such that the curing time, that is, the release rate of Ca ⁺⁺ ions necessary for curing, is controlled by the amount of amorphous component contained. Because it forms a homogeneous hardened body with alkali silicate and at the same time does not release excessive Ca ⁺⁺ than necessary,
There is also less formation of calcium salts, which cause efflorescence, and the cured product has good water resistance after drying and heating.
It is considered to have excellent acid resistance, efflorescence resistance, and dimensional properties. Furthermore, the presence of M ₂ O in the composition of the amorphous calcium silicate alkali according to the present invention acts to promote the elution of Ca ⁺⁺ ions from the amorphous calcium silicate alkali, and By adjusting the amount, the curing time of the alkali silicate can be adjusted. Although the mechanism for regulating this curing time is not clear, its effect is first exhibited by the homogeneous amorphous calcium silicate alkali obtained by adding M ₂ O component as an amorphous component during calcium silicate amorphization. However, the same effect cannot be obtained with amorphous calcium silicate alkali obtained by simply post-adding M ₂ O to amorphous calcium silicate. The amorphous calcium silicate alkali according to the present invention can be used alone as a room-temperature curing agent for alkali silicate to obtain a desired curing time, and in this case, it can be used in combination with other curing accelerators, curing retarders, etc. Since there is no need to do this, workability during construction is also simplified.
In addition, there is little variation in curing time due to temperature changes.
The reproducibility is also good. Further, when using the curing agent for alkali silicate of the present invention, by adjusting the amount, it is possible to arbitrarily set the curing time of the alkali silicate from several minutes to several hours. Furthermore, the material strength of the cured product after drying and heating,
It has excellent properties such as adhesive strength, water resistance, acid resistance, heat resistance, weather resistance, efflorescence resistance, organic solvent resistance, and dimensional properties, and can be used in a wide range of fields where alkali silicate has traditionally been used as a binder. For example, as aggregates, lightweight aggregates such as lightweight siyamoto, expanded clay, and perlite, aluminas such as calcined bauxite, sintered alumina, fused alumina, and bubble alumina, silicon dioxide, chromium oxide, magnesium oxide, zirconium oxide, and zircon. Using various ceramic raw materials such as, pouring, troweling,
It can be used for manufacturing castable refractories, refractory mortar, and other monolithic refractories by construction methods such as spraying and vibration. In addition, as inorganic fillers, kaolin, talc,
Clays such as bentonite, glassy substances such as perlite, shirasu balloons, glass beads, frits, asbestos, rock wool, glass fibers, ceramic fibers,
Using fibrous materials such as pulp fiber, calcium carbonate, titanium oxide, silica sand, diatomaceous earth, etc., mortar walls,
Concrete walls, slate boards, wood wool boards, plaster boards,
Can be used for surface decoration of building materials such as silica plates and ALC plates, metal plates such as iron plates, galvanized steel plates, and aluminum plates, protective paints, flame-retardant/noncombustible paints, zinc-rich paints, and adhesives thereof. . For these uses, inorganic/organic pigments, water reducing agents, dispersants, thickeners, foaming agents, antifoaming agents, etc. can be used as appropriate depending on the purpose. EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. Examples 1 to 4 and Comparative Examples 1 to 2 Limestone, silica sand, soda carbonate, alumina sand,
A predetermined amount of fluorite and phosphate rock was blended, heated and melted at 1350°C, and then rapidly cooled with water to obtain amorphous calcium sodium silicate having the chemical composition shown in Table 1 and exhibiting an amorphous rate of 70% or more. Ta.

[Table] The above amorphous calcium sodium silicate was pulverized with a vibrating mill to obtain a powder with 100% passing through 100 mesh and 80% passing through 325 mesh. Next, add 100g of powdered sodium silicate (SiO ₂ /
_Na2O molar ratio 2.79, water 20.9% by weight),
42g of the above amorphous calcium sodium silicate, 4200g of sintered alumina shown in Table 2, and 336g of water (20℃)
was added and mixed for 3 minutes using a Hobart mixer, and then a molded article was prepared according to the method of JIS-R-2553.
After curing the molded body in a hermetically sealed container at 20°C for 24 hours,
It was dried at 110°C for 10 hours and fired at 1000°C for 3 hours. Table 3 shows the curing time at 20°C and the strength test results at each temperature. In addition, a test was conducted under the same conditions as in Example 1 using sodium silicofluoride (Comparative Example 1) and a commercially available phosphate curing agent (Comparative Example 2) instead of amorphous calcium sodium silicate, and using the same amounts used and the same conditions as in Example 1. The results are also listed in Table 3.

【table】

【table】

[Table] Examples 5 to 8 and Comparative Examples 3 to 6 Amorphous calcium sodium silicate powder having the chemical composition shown in Table 4 in the same manner as Examples 1 to 4 and exhibiting an amorphous rate of 40% or more. I got it. Next, 100g of powdered potassium silicate (SiO ₂ /
K ₂ O molar ratio 3.04, moisture 16.8% by weight), 320 g of water, and the above amorphous calcium sodium silicate were mixed and stirred, and the curing time at 20° C. was measured. In addition, the above amorphous calcium sodium silicate was heated at 900°C for 1
The product was fired for a period of time to crystallize, and the same measurements were performed as a comparative example. The results are shown in Table 5.

【table】

[Table] Example 9 and Comparative Examples 7 to 8 The cured rectangular parallelepiped bodies (4 x 4 x 16 cm) molded according to Example 4 and Comparative Examples 1 and 2 were airtightly cured for 24 hours and dried at 110°C for 10 hours. . Next, these were mixed with tap water heated to 80℃, a 10% by weight sulfuric acid aqueous solution,
After being immersed in 10% by weight hydrochloric acid aqueous solution 1 for 6 hours, it was air-dried for 18 hours. The above operation was repeated three times in total, and the surface condition was observed, dimensional shrinkage rate, bending strength, and compressive strength were measured. After drying again at 110°C for 10 hours, the compressive strength was measured. The results are shown in Table 6.

[Table] Examples 10 to 17 Limestone, silica stone, potash carbonate, alumina sand, and fluorite are blended in predetermined amounts and melted and rapidly cooled to produce an amorphous product having the chemical composition shown in Table 7 and exhibiting an amorphous rate of 70%. A quality calcium potassium silicate powder (No. 9) was obtained.

【table】

[Table] The above amorphous calcium potassium silicate (No. 9) as a hardening agent and the amorphous calcium sodium silicate of Examples 2 and 4 in Table 1 prepared in Examples 1 to 4 were added to various sodium silicate aqueous solutions (aqueous glass) and the curing time was measured. Blend examples and results are shown in Table 8.

【table】

[Table] Approximately 2 pieces of the above mixture is placed on an iron plate (length 10cm x width 10cm).
It was applied to a thickness of mm, left indoors for 24 hours, dried at 110°C for 10 hours, and then cured for 7 days in a constant temperature and humidity chamber at 80°C and 80% humidity. After curing, the coated surface showed good adhesion with no peeling or efflorescence observed. As shown in Examples 1 to 17 and Comparative Examples 1 to 8, the amorphous calcium silicate alkali according to the present invention can be used alone as a room temperature curing agent for alkali silicate to set an arbitrary curing time, and its reproducibility and It is recognized that this curing agent has excellent workability and, at the same time, has excellent effects on the strength of the cured product after drying and heating, as well as various properties such as water resistance, acid resistance, and dimensional properties. Examples 18 to 23 and Comparative Examples 9 to 12 As shown in Table 9, quartzite, sodium carbonate, phosphate rock, alumina sand, and fluorite were blended, heated and melted at 1400°C, and then quenched by granulation. did.

[Table] The above Examples 18 to 23 all melted completely and
The line powder diffraction pattern showed a completely amorphous pattern (the circle mark indicates an amorphous rate of 90%). On the other hand, Comparative Examples 9 to 12 were all unmelted,
CaSiO ₃ , Ca ₃ Si ₂ O ₇ , 2CaO・Al ₂ O ₃・SiO ₂ ,
CaO・Al ₂ O ₃・2SiO ₂ , CaSiO ₂ F ₂ , Ca(PO ₄ ) ₂・
Crystal mixtures such as CaF ₂ (x indicates amorphous rate 1 to 30
%).

Claims (1)

[Scope of Claims] 1. A curing agent for alkali silicate, characterized by containing an amorphous alkali calcium silicate as an active ingredient. 2 Amorphous calcium silicate alkali is CaO (or
When the molar ratio of CaO + MgO)/SiO ₂ is 1.8 or less, CaO
(or CaO + MgO) 10-65% by weight, SiO ₂ 15-75% by weight, M ₂ O (M represents an alkali metal) 0.5-20% by weight, Al ₂ O ₃ (or Al ₂ O ₃ + Fe ₂ O ₃ ) The curing agent for alkali silicate according to claim 1, having a composition of 1 to 10% by weight, F1 to 7% by weight, and 0 to 16% by weight _{of P2O5} . 3. The curing agent for alkali silicate according to claim 1 or 2, wherein the amorphous calcium alkali silicate is amorphous sodium calcium silicate and/or amorphous calcium potassium silicate. 4 Claims 1 to 3 in which the amorphous alkali calcium silicate has an amorphous rate of 40% or more
A curing agent for alkali silicate according to any one of the items.