JPH078747B2 - Method of manufacturing ceramic products - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a method for manufacturing a ceramic product in which cement is hydrated and hardened and then sintered and hardened, and more particularly to a method for manufacturing a ceramic product having sufficient strength immediately after sintering.

[Prior art]

Ceramic products are molded, then dried and fired to cure. However, the ceramic products manufactured by this method have the disadvantage that they are not sufficiently strong before sintering and are weak and inconvenient to handle. In addition, the ceramic product has a large shrinkage during the drying and sintering processes, and has a defect that the product is largely warped and distorted. In order to eliminate this drawback, cement is mixed with the raw material, after molding, the cement is hydrated and hardened so that it has sufficient strength for handling before sintering, and then sintered and further hydrated and hardened. A manufacturing method for ceramic products has been developed (Japanese Patent Publication No. 61-4829). The method of manufacturing this ceramic product is based on a hydraulic base material such as cement.
Mix 30 to 1500 parts by weight of flux such as shirasu, volcanic ash, glass powder, etc. to 100 parts by weight, hydrate and harden it before and after sintering, and harden it by hydration hardening and sintering during firing. There is. However, in this manufacturing method, since the porcelain product is made to have strength by further undergoing hydration hardening treatment after sintering, it takes time and labor for post-treatment after firing, and the ceramic product with sufficient strength is also available. There was a drawback that the product could not be realized. That is, this method of manufacturing a ceramic product is based on a full-scale hydration hardening treatment after firing, and in the case of underwater curing, 50 ° C x 3 days to 60 days.
° C. × 7 days also processing days and temperature and is necessary, moreover, the bending strength after hydration hardening treatment also was about 100~180kgf / cm ^2. Furthermore, a method for producing a cement product has been developed in which a flux is mixed with cement and then hydrated and hardened after firing. This method is disclosed, for example, in JP-A-52-121019, JP-A-54-41916, JP-A-59-73482, and JP-A-57-6.
No. 7087. The manufacturing methods described in these publications are ones in which a cement-containing fired material is fired and hydrated and hardened. However, even in these methods, a predetermined strength is obtained by hydration-curing after firing, and sufficient strength cannot be obtained immediately after firing, and it takes time and time for the hydration-curing treatment after firing. And there was a drawback that required heating energy. Furthermore, a method for producing a cement sintered body has been developed in which a sintered material such as cement or glass is mixed with water in an aggregate, molded and aged, and then sintered at 1050-1150 ° C. (Japanese Patent Laid-Open No. Sho 50).
-121305). This method sinters what has been molded and cured with cement, so there is no need to hydrate the cement after sintering.

[Problems to be Solved by the Invention]

However, this method has the drawback that the cement cannot be made sufficiently strong because it is fired at an extremely high temperature of 1050-1150 ° C. Since the cement only vaporizes free water below 100 ° C, the strength does not decrease at all in this temperature range. At around 260 ° C, the water of crystallization in the cement hydrate begins to dehydrate and the strength gradually decreases.
If the temperature exceeds 500 ° C, the Ca (OH) ₂ dehydration and decomposition will become severe and the strength will further decrease. Further, when the temperature exceeds 750 ° C., gas decomposition of CaCO ₃ occurs and the strength is significantly reduced. Curve A in FIG. 1 shows the change in strength of concrete with temperature. As is clear from this figure, concrete has the property that its strength remarkably decreases as the heating temperature increases. Therefore, despite the fact that a large amount of cement is mixed in the sintering mixture, the ceramic product fired at high temperature can hardly be expected to have strength due to cement. Cement is only used to preform the sinter mixture. By the way, a ceramic product is manufactured by mixing a sintered mixture with a ceramic raw material such as glass powder or a siliceous raw material and firing the mixture. Ceramic materials have the property that their strength gradually increases as the sintering temperature increases. This is because the ceramic raw material is sufficiently melted and strongly sintered in the firing process. The curve B in FIG. 1 shows the strength change of the ceramic raw material with respect to the firing temperature. As shown by this curve, the strength of the ceramic raw material increases as the firing temperature increases.
That is, it has the opposite physical properties as cement. Needless to say, it is important for the ceramic product obtained by mixing and firing the cement and the ceramic raw material to have sufficient strength with both the cement and the ceramic raw material. However, as indicated by the curves A and B in FIG. 1, cement and ceramic raw materials exhibit mutually contradictory physical properties, and it is not possible to add both strengths of cement ceramic raw materials to make them tough. The present invention was developed for the purpose of eliminating the drawbacks of these conventional methods for producing a ceramic product, and an important object of the present invention is that the frit which has been conventionally mixed with glaze for surface treatment. By mixing with cement, it can be fired at a low temperature, extremely strong strength can be obtained after firing, and it is possible to omit the hydration hardening treatment after firing, which can reduce the manufacturing cost and also in a short time. It is also to provide a manufacturing method capable of mass-producing ceramic products. Another important object of the present invention is that the strength after firing is extremely strong, and since the shrinkage rate in the firing process is small, large panels can be manufactured, and most types of glaze treatment are applied to the surface. It is to provide a manufacturing method of a ceramic product capable of manufacturing.

[Means for Solving the Problems]

In the method for producing a ceramic product of the present invention, a frit having a specific yield point is added in order to have sufficient strength in both the production method and the ceramic raw material. That is, the method for manufacturing a ceramic product of the present invention, 25 to 60 parts by weight of cement, which has been added and mixed as a bone agent of conventional cement, shirasu, volcanic ash, glass powder, dregs, porcelain chamotte, etc., 10 to 60 parts by weight of the frit used in the glaze was added and mixed, and further, 40 parts by weight or less of glass powder and 40 parts by weight or less of either or both of the siliceous raw materials were added and mixed with water. It is kneaded and molded into a desired shape. A frit is a specific yield point, that is, the yield point
Use a temperature of 500-700 ℃. As the frit, for example, the following may be mixed in the following weight ratio, melted, and crushed. Lead white 116, feldspar 111, silica sand 28, limestone 20, zinc white 12,
Clay 21 Silica sand 60, Salt stone 22, Salt 7.2, Alum 3.6, Soda ash 3.6, Gypsum 3.6 The frit can be adjusted in melting point with a mixed material. If the mixing amount of the frit is too small, the firing temperature becomes high, and the warpage or distortion of the fired ceramic product becomes large. On the contrary, if the frit is too large, the strength before firing is substantially decreased due to a substantial decrease in the cement mixing amount. descend. In the preforming process, the formed product is hydrated and hardened in the contained cement to be cured to a strength capable of holding the shape by itself, and the handling before firing is remarkably simplified. The preformed product is sintered at 750 ° C to 1000 ° C and is of sufficient strength without subsequent hydration hardening. As the cement used in the method for producing a ceramic product of the present invention, Portland cement, alumina cement, blast furnace slag cement, fly ash cement and the like can be used. The cement contained in the ceramic product of the present invention is mixed in order to provide convenient strength for handling the molded product before molding and firing. If the amount of this cement mixed is too small, it cannot be hardened to a strength convenient for handling in the hydration hardening treatment step before firing, while if it is too large, the strength of the ceramic product after firing is weak. In addition to cement, 0.5 to 100 parts by weight of cement
It is also possible to mix 3 parts by weight of a water reducing agent and a fluidizing agent.
Examples of water reducing agents include Mighty 15 from Kao Soap Co., Ltd.
0. As the fluidizing agent, LEVERON manufactured by Sanyo Chemical Co., Ltd. can be used. When glass powder is mixed with ceramic products, the expansion coefficient can be adjusted by changing the type and mixing amount of glass to be mixed, preventing cracks and distortion during the firing process, and cheaper than frit. Raw material cost can be reduced by using simple glass powder. The glass powder does not necessarily have to be mixed, but if the mixing amount is too large, the mixing amount of the frit and the cement decreases, so that there is a drawback that the firing temperature becomes high or the glass powder becomes soft before firing. Instead of glass powder, or as a siliceous raw material to be mixed in addition to this, feldspar, kaolinite, clay, pyrophyllite, bentonite, inorganic powder or granular material fired from shale as a raw material, etc. Can be used. Like the glass powder, the siliceous raw material also has a drawback that if the mixing amount is too large, the mixing amount of the frit and the cement decreases, so that the firing temperature becomes high or becomes weak before firing. In consideration of the strength before and after firing, the mixing amount of cement, frit, glass powder, and siliceous raw material is specified in the above range.

[Action]

The method for manufacturing a ceramic product of the present invention achieves sufficient strength in both cement and a ceramic raw material by using a frit having a specific yield point. The method for producing a ceramic product of the present invention uses a frit having a yield point in the range of 500 to 700 ° C. The ceramic raw material containing the frit becomes stronger as the firing temperature is increased, as shown by the curve C in FIG. However, as indicated by the curve A, the strength of cement becomes weaker as the firing temperature becomes higher. In the method for manufacturing a ceramic product of the present invention, the yield point of the frit is set to a specific temperature so that the curve A and the curve C sufficiently cross over, and both the curve A and the curve C have strength. It is characterized by firing in a temperature range. Therefore, the ceramic product manufactured by the method of the present invention has a characteristic that it can be made extremely strong by the synergistic effect of the strength of cement and the strength obtained by firing the ceramic raw material. In FIG. 1, the curve D
Indicates the sum of the strength of the cement of curve A and the strength of the sintered body of curve C. The ceramic product produced by the method of the present invention is fired at 750 to 1000 ° C. Therefore, as indicated by the arrow, it is possible to achieve a strength that cannot be achieved by cement and the sintered body alone.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. However, the examples shown below are specific examples for embodying the technical idea of the present invention, and the method for manufacturing a ceramic product of the present invention is not limited to the following. The manufacturing method of the present invention has various modifications within the scope of the claims. Example 1 Bottle glass is crushed and 30 parts by weight of glass powder and 30 parts by weight of frit are crushed by a crusher to produce a crushed glass-containing mixture of glass and frit. To the obtained glass-containing mixture, 40 parts by weight of Portland cement and 30 parts by weight of water are mixed and thoroughly mixed. The frit includes XT-172 of Nippon Frit Co., Ltd. (body expansion coefficient 222 × 10 ^-7 , yield point 670 ° C) and Frit No. 3907 of Japan Fellow Co., Ltd. (body expansion coefficient 334 × 10 ^-7 , yield point) Five
10 ℃), and use the one whose yield point is 580 ℃. The obtained kneaded product is molded into a plate shape and subjected to a hydration hardening treatment to be hardened to a strength convenient for handling. In forming the kneaded product, a mold having an open top is placed horizontally, and the kneaded product is filled into the mold with a uniform thickness. The product molded in the mold developed above is left as it is for several hours to 20 hours, then demolded and cured in air at room temperature for 1 to 8 days for hydration hardening. . The hydration-cured product is baked in a net conveyor kiln for 3 hours. Net Conveyor Kiln's conveyor net is
The mixed raw material was set to have a width of 900 mm and a uniform thickness, the time from the inlet to the outlet was 3 hours, and the firing temperature was 850 ° C. The obtained plate-shaped ceramic product had the following extremely excellent characteristics. By the way, the bending strength of the ceramic product treated by the conventional method, that is, the steps of preliminary hydration hardening-calcination-real hydration hardening was 100 to 180 kgf / cm ² . Bending strength …… 235kgf / cm ² Tensile strength …… 93kgf / cm ² Compressive strength …… 826kgf / cm ² Shear strength… 164kgf / cm ² Impact strength …… 1.26kg ・ cm / cm ² Water absorption rate …… 13〜19 weight % [Example 2] A plate-shaped ceramic product was manufactured in the same manner as in Example 1 except that the firing temperature of the rotor kiln was increased from 850 ° C to 900 ° C. The obtained ceramic product showed the following extremely excellent properties, although it was not subjected to hydration hardening treatment after firing as in Example 1. Bending strength …… 334 kgf / cm ² (about 2-3 times stronger than conventional products) Tensile strength …… 96 kgf / cm ² Compressive strength …… 1173 kgf / cm ² Shear strength 345 kgf / cm ² (Measurement limit of the measuring device is It was 345 kgf / cm ² and tougher than this.) Impact strength was 1.39 kg · cm / cm ² Water absorption rate 13 to 19% by weight [Example 3] 50 parts by weight of cement mixture, 20 parts by weight of glass powder A plate-shaped ceramic product was manufactured in the same manner as in Example 1 except that the parts by weight were used. In this manufacturing method, since the amount of the glass powder mixed is decreased and the amount of the cement mixed is increased, the bending strength after firing is 267 kgf / cm ² and the ceramic product 80 obtained in Example 2 %, But the strength was about 2-2.5 times that of conventional ceramic products. [Example 4] Further, a plate-like ceramic product was prepared in the same manner as in Example 1 except that the mixing amount of cement was 50 parts by weight, the mixing amount of glass powder was 30 parts by weight, and the mixing amount of frit was 20 parts by weight. Was manufactured. In this ceramic product manufacturing method, since the amount of cement mixed was increased and the amount of frit mixed was decreased, the bending strength was 201 kgf / cm ² . [Example 5] A fired inorganic powder granule obtained by foaming and sintering 30 parts by weight of glass powder of clay, soda ash, and sodium nitrate was pulverized.
A plate-shaped ceramic product was manufactured in the same manner as in Example 1 except that the siliceous raw material containing 58.36 wt% of SiO ₂ and 10.49 wt% of Al ₂ O ₃ was changed to 30 parts by weight. The obtained ceramic products exhibited the following excellent properties, even though they were not subjected to hydration hardening treatment after firing. Bending strength …… 211kgf / cm ² Tensile strength is 86kgf / cm ² Compressive strength is 786kgf / cm ² Shear strength is 154kgf / cm ² Impact strength is 1.11kg ・ cm / cm ² Water absorption rate is 13 ~ 19wt% [Example 6] The siliceous raw material has a SiO ₂ content of 92.5 wt% and an Al ₂ O ₃ content of
A plate-shaped ceramic product was manufactured in the same manner as in Example 4 except that the artificial lightweight aggregate of 5.7 wt% was used instead. The obtained ceramic products exhibited the following excellent properties, even though they were not subjected to hydration hardening treatment after firing. Bending strength is 218 kgf / cm ² Tensile strength is 82 kgf / cm ² Compressive strength is 752 kgf / cm ² Shear strength is 147 kgf / cm ² Impact strength is 1.13 kg · cm / cm ² Water absorption rate is 13 to 19% by weight [Example 7 ] 30 parts by weight of glass powder, 15 parts by weight of glass powder, and SiO ₂ 77.65w
A plate-like ceramic product was manufactured in the same manner as in Example 1 except that 15 parts by weight of a siliceous raw material containing t% and Al ₂ O ₃ 16.84 wt% was used. The obtained ceramic product showed the following characteristics, though not subjected to hydration hardening treatment after firing. Bending strength …… 223 kgf / cm ² Tensile strength 89 kgf / cm ² Compressive strength 801 kgf / cm ² Shear strength 157 kgf / cm ² Impact strength 1.20 kg · cm / cm ² Water absorption 13 to 19% by weight Example 5 In addition, the ceramic product manufactured in Example 7 uses the siliceous raw material instead of the glass powder or by reducing the mixing amount of the glass powder.
The strength is slightly lower than that of products using glass powder, but the feature is that the glaze treatment can be finished beautifully. By the way, the kneaded material in which the cement, the frit, the glass powder and / or the siliceous raw material and the water are mixed does not necessarily have to be filled in a mold having an opening at the top to be molded. It is also possible to fill the kneaded product and perform pressure dehydration molding to form a predetermined shape, for example, a plate shape. For products that are molded by pressure dehydration with a mold, hold the mold clamped state for a few seconds to tens of minutes, then open the mold and place it on the underlying mold for several hours to several days. It is left to stand, then demolded, cured in air at room temperature for 1 to 7 days to be hydrated and cured, and then baked. It is hydrated and hardened for easy handling, for example,
In the case of a plate, the baking temperature of the product hardened to have strength at both ends is usually 750 to 1000 ° C, preferably 800.
Adjusted in the range of ~ 950 ° C. The optimum firing temperature is determined in consideration of the type and mixing amount of the frit, the required strength and the dimensional accuracy. When the firing temperature is high, the strength after firing is improved, but the dimensional accuracy is reduced. If a frit having a low melting point is used and the frit is mixed in a large amount, a ceramic product having high strength can be obtained by low temperature firing. The firing time is determined in consideration of the firing temperature, the temperature gradient of heating and cooling, the mixed raw material, the required strength, the fuel consumption amount used for firing, etc., but is usually 20 minutes to 8 hours, preferably 1 to
Adjusted to a range of 5 hours. In the above examples, Portland cement was used as the cement, but other types of cement can be used. For example,
A ceramic product manufactured by the same raw material and manufacturing method as in Example 1 under the same conditions except that Portland cement was replaced with early-strength cement had a bending strength of 211 kgf / cm even though hydration hardening treatment was not performed after firing. ^It is extremely tough with a tensile strength of 77 kgf / cm ² , and a compressive strength of 685 kgf / cm ² ,
Shear strength is 202kgf / cm ² , impact strength is 1.29kg ・ cm / cm ² ,
The water absorption rate was 13 to 19% by weight, and the other properties were remarkably excellent. Furthermore, a ceramic product manufactured by the same raw material and manufacturing method as in Example 2 under the same conditions except that Portland cement was replaced with early-strength cement had a bending strength of 282 kgf, even though hydration hardening treatment was not performed after firing. / cm ² and a remarkably tough, further, the tensile strength 80 kgf / cm ^2, compression strength is 819kg
f / cm ² , shear strength 297kgf / cm ² , impact strength 1.30kg ・ c
It was remarkably excellent at m / cm ² .

【The invention's effect】

The method for producing a ceramic product of the present invention is changed to cement,
A frit having a yield point of 500 ° C to 700 ° C is mixed in a specific ratio. Cement mixed with frit can be preformed by hydration reaction of cement and then 750-1000
Sinter at ° C. That is, in the method for manufacturing a ceramic product of the present invention, the strength curve A of the cement, the strength of which decreases as the firing temperature increases, and the strength curve C of the sintered body, the strength of which increases when the firing temperature increases, sufficiently crossover. As described above, the yield point of the frit is adjusted to a specific range, and the frit is fired in a specific temperature range so that both the cement and the sintered body are significantly toughened. That is, in the method for manufacturing a ceramic product of the present invention, the ceramic product manufactured by the conventional method of preforming with cement and then baking by firing in the temperature range shown by the arrow of the curve D has excellent strength. be able to. By the way, in the method of manufacturing a sintered ceramic product after preforming cement, it is extremely important to lower the firing temperature of the preformed product. This is because this method is suitable for manufacturing large porcelain products.
Small ceramic products do not need to be preformed using cement or the like. This is because the small one has sufficient shape retention strength to be able to be fired in a state where the ceramic material is kneaded with water and molded. Large porcelain products do not have sufficient shape retention strength in the state of being kneaded with water and molded, and have the drawback of being deformed when being carried into a firing furnace. For this reason, large porcelain products are preformed with cement and have a shape-retaining strength that prevents them from being deformed when they are carried into a firing furnace. By the way, a ceramic product obtained by sintering an inorganic material has excellent physical properties that cannot be realized by a product in which powder particles are bonded with a binder such as an adhesive or cement. It has excellent weather resistance and almost negligible aging. Therefore, it has a feature that it does not deteriorate even if it is used for many years. However, the biggest drawback of ceramic products manufactured by this method is that the dimensional accuracy cannot be increased. Dimensional accuracy considerably limits the application of ceramic products. Therefore, it is extremely important to improve the dimensional accuracy of ceramic products. The manufacturing method of the present invention can realize the feature that the dimensional accuracy can be increased in addition to reducing the manufacturing cost. This is because cement is mixed and preformed to obtain sufficient shape retention strength, and in this state, low temperature firing is performed to sinter the cement. A molded product having improved shape retention strength by preforming can prevent distortion in the firing process. Furthermore, by lowering the firing temperature, distortion during firing can be reduced. Therefore, the method for manufacturing a ceramic product of the present invention realizes an extremely excellent feature that a large product can be manufactured, mass production can be performed efficiently at low cost, and further dimensional accuracy of the product can be increased.

[Brief description of drawings]

FIG. 1 is a graph showing the manufacturing method and changes in strength of ceramic raw materials with respect to temperature.

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Claims (1)

[Claims] 1. Cement 25 to 60 parts by weight, at least 40 parts by weight or less of glass powder and 40 parts by weight or less of siliceous raw material, and 10 to 60 parts by weight of a frit having a yield point of 500 to 700 ° C. A step of forming a sintered mixture containing a required amount of water into a desired shape, and hydration hardening the cement contained in the formed product,
It consists of a preforming process that cures the product itself to a strength that allows it to retain its shape, and a sintering process that sinters the preformed product at a temperature of 750 ° C to 1000 ° C. A method for manufacturing a ceramic product that is hardened to a high strength.