Manufacturing methods for bone china products

Abstract

To provide a manufacturing method for a bone china product, contributing to improvements in environmental problems, by removing egg shell membranes from egg shells.SOLUTION: A manufacturing method for a bone china product includes an egg shell treatment step of forming treated egg shells by firing untreated egg shells having attached egg shell membranes at a temperature of 300°C or over and 900°C or under to remove the egg shell membranes from the untreated egg shells and a preparation step of blending a CaCO3 supply source and a material other than the CaCO3 supply source for preparation of a raw material composition of a bone china product, wherein the bone china product manufacturing method includes blending the treated egg shells as a part or all of the CaCO3 supply source in the preparation step.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing bone china products.

Background Art

[0002] Porcelain includes hard porcelain and soft porcelain. Among them, bone china, which is soft porcelain, has an excellent white color and is excellent in terms of translucency, aesthetic properties, strength, etc., and is widely used as tableware and decorative porcelain. As a bone china product, the one described in Patent Document 1 is known. The raw materials of bone china include feldspar, clay, kaolin, limestone, and bovine bone ash, etc.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Recently, due to the increasing interest in environmental issues, attempts have been made to reuse waste that was conventionally discarded. For example, it is conceivable to supply limestone contained in the raw materials of the above-mentioned bone china products with eggshells that were conventionally discarded. Thereby, it is desired to improve environmental problems.

[0005] However, an eggshell membrane adheres to the eggshell. Due to this eggshell membrane, there is a risk that the sieve used in the process of separating impurities and coarse particles contained in the raw material composition will become clogged during the process of manufacturing bone china products. For this reason, there has been a problem that it is difficult to use eggshells with an eggshell membrane attached as a raw material for bone china products.

[0006] This invention was made in view of the above background, and aims to provide a method for manufacturing bone china products that contributes to improving environmental problems by removing the eggshell membrane from the eggshell. [Means for solving the problem]

[0007] One aspect of the present invention is, An eggshell processing step involves firing untreated eggshells with the eggshell membrane attached at a temperature of 300°C to 900°C to remove the eggshell membrane from the untreated eggshells and produce treated eggshells. A method for manufacturing bone china products, comprising a preparation step of preparing a raw material composition for bone china products by mixing a source of CaCO3 with materials other than the source of CaCO3, In the preparation step, the processed eggshells are mixed as part or all of the CaCO3 source. The raw material composition is prepared by doing so, and further, The process involves mixing water with the raw material composition and grinding it to prepare a slurry, The process comprises a step of sieving the aforementioned slurry, It is found in the manufacturing method of bone china products. [Effects of the Invention]

[0008] According to one aspect of the present invention, processed eggshells can be obtained from which the eggshell membrane attached to untreated eggshells has been removed. This prevents the sieves used in the process of removing impurities and coarse grains from becoming clogged with eggshell membrane, so that the processed eggshells can be used as a raw material for bone china products. As a result, by reusing eggshells, which are food industry waste, the amount of eggshell waste can be reduced, thereby improving environmental problems. [Modes for carrying out the invention]

[0009] 1. About bone china The bone china according to the present invention will now be described. According to JIS S2401, bone china is defined as "a material whose base consists of at least tricalcium phosphate, anorthite, and glass." Furthermore, "the content of tricalcium phosphate must be 30% by mass or more."

[0010] Traditionally, bone china has been made from bovine bone ash, limestone, feldspar, kaolin, pottery stone, and clay. Furthermore, bone china may also contain recycled materials from recycled bone china, as described later.

[0011] Limestone, one of the raw materials for bone china, contains CaCO3. By replacing all or part of this CaCO3 with waste containing CaCO3, it is possible to reduce the amount of waste, which is expected to improve environmental problems. Eggshells are an example of waste containing CaCO3.

[0012] Since the recycled bone china mentioned above contains CaCO3, replacing the CaCO3 in the recycled bone china with eggshells can further improve environmental conditions.

[0013] 2. Regarding the manufacturing method of bone china products Next, a method for manufacturing bone china products according to the present invention will be described. An example of a method for manufacturing bone china products is shown below.

[0014] (1) By calcining untreated eggshells with the eggshell membrane attached, the eggshell membrane is removed from the untreated eggshells, and treated eggshells are produced. (2) A raw material composition for bone china products is prepared by mixing a CaCO3 source with materials other than the CaCO3 source. CaCO3 sources include processed eggshells, limestone, and recycled bone china. Materials other than the CaCO3 source include bovine bone ash, feldspar, kaolin, pottery stone, clay, and recycled bone china. Recycled bone china can be used as both a CaCO3 source and a material other than the CaCO3 source. (3) Water is mixed with the raw material composition, and the raw material composition containing water is crushed to a predetermined particle size (median particle size 4.6 to 6.9 μm) and mixed to prepare a slurry. (4) The slurry is sieved using a vibrating sieve or the like to separate impurities or coarse particles contained in the raw material composition. The vibrating sieve has a mesh size of 300 (mesh opening of 0.045 mm). Coarse particles with a particle size of 45 μm or larger are separated by the vibrating sieve. The separated coarse particles are discarded. (5) The moisture content is reduced by a filter press to form a flat cake. (6) After the moisture content has been adjusted, the material is formed into a predetermined shape by pottery wheel molding or slip casting. (7) Bake at approximately 1250°C (for example, 1220-1260°C). (8) Spray the glaze in which the frit is dispersed in water. (9) Glaze and fire at approximately 1150°C (for example, 1110-1190°C).

[0015] 3. Removal of eggshell membrane Next, we will explain the eggshell processing process for removing eggshell membrane from unprocessed eggshells. Unprocessed eggshells recovered from the manufacturing process of egg products have eggshell membrane attached to them. Since this eggshell membrane is organic matter, it is an impurity from the perspective of bone china raw materials. In the bone china manufacturing process, there is a concern that the sieves used in the process of removing impurities and coarse grains may become clogged with eggshell membrane. This may reduce the efficiency of the sieving process. Therefore, in order to improve the efficiency of bone china manufacturing, it is desirable to remove the eggshell membrane from unprocessed eggshells.

[0016] As a method for separating the eggshell membrane from the eggshell, for example, as described in JP-A-2020-146604, a method of putting a shell with the eggshell membrane attached in an alkaline solution and generating a rotating water flow to separate the membrane and the shell, or as described in JP-A-7-227551, a method of putting a shell with the eggshell membrane attached into a jet mill, pulverizing it finely while peeling the eggshell and the eggshell membrane, and separating it by a vibrating sieve or air current separation, and also as described in JP-A-8-173838, a method of separating by specific gravity difference in a water flow, etc. are known. However, no matter which method is used, it is difficult to completely separate the eggshell and the eggshell membrane, so the eggshell membrane remains partially on the eggshell. As described above, as a method for completely removing the eggshell membrane from the eggshell, since the eggshell membrane is composed of protein, it is efficient to perform heat treatment to burn off the eggshell membrane.

[0017] In this form, the eggshell membrane is removed from the untreated eggshell by firing the untreated eggshell. The eggshell membrane can be removed from the untreated eggshell by firing the untreated eggshell at a temperature of 300°C or higher. Thereby, clogging of the sieve by the eggshell membrane is suppressed, so that it becomes possible to use the eggshell as a raw material for bone china products. Thereby, since the eggshell that has been discarded as waste can be used as a raw material for bone china products, environmental problems can be improved.

[0018] CaCO3 contained in the eggshell undergoes a chemical change to CaO when heated at a temperature higher than 900°C. CaO generates heat when it undergoes a chemical change to Ca(OH)2 upon contact with moisture. Therefore, when manufacturing bone china products, it is necessary to chemically change CaO to CaCO3 at a stage prior to the step of adding water to the raw material composition, so the handling is troublesome. For this reason, it is preferable to fire the untreated eggshell at 900°C or lower at which the eggshell does not chemically change to CaO. From the above viewpoints, the untreated eggshell is preferably fired at 300 to 900°C, more preferably 500 to 700°C. Thereby, it is possible to obtain a treated eggshell in a state where the eggshell membrane has been removed and CaCO3 has been maintained.

[0019] 4. Regarding CaCO3 The raw material composition of the bone china product includes a source of CaCO3. Examples of the source of CaCO3 include limestone, treated eggshells, and recycled bone china. The main component of limestone is CaCO3. Also, the main component of the treated eggshells from which the eggshell membrane has been removed according to the present invention is also CaCO3.

[0020] When the recycled bone china is not used in the raw material composition of the bone china product, for example, the proportion of limestone in the raw material composition can be 16.2% by mass. By replacing at least a part or all of the above limestone with treated eggshells, environmental problems can be improved.

[0021] The recycled bone china is for reusing the defective bone china products. The recycled bone china includes waste that has been made defective before the raw material composition is sintered or glazed, and also includes waste that has been made defective after the raw material composition is sintered or glazed. Since the recycled bone china contains 16.2% by mass of Ca component in terms of limestone (CaCO3), the recycled bone china can be used as a source of CaCO3. By using the recycled bone china as a source of CaCO3, it is possible to reuse the defective bone china products that were conventionally discarded as waste clay, and thus further improve environmental problems.

[0022] When recycled bone china is used in the raw material composition of bone china products, for example, if the proportion of recycled bone china to the raw material composition is 9.0% by mass, the proportion of limestone to the raw material composition can be 14.7% by mass. By replacing at least part or all of the above limestone with processed eggshells, environmental problems can be improved. Since the CaCO3 contained in the raw material composition changes to CaO when fired or glazed, the Ca component contained in recycled bone china will be considered in terms of limestone (CaCO3) below. Since recycled bone china contains 16.2% by mass of Ca component in terms of limestone, the proportion of Ca component derived from recycled bone china in terms of limestone can be 1.46% by mass. Furthermore, by replacing at least part or all of the Ca component derived from recycled bone china with processed eggshells, environmental problems can be improved. However, recycled bone china can be added up to 30% by mass of the raw material composition. In this case, the proportion of limestone in the raw material composition is 11.3% by mass, and the proportion of Ca component derived from recycled bone china in terms of limestone equivalent is 4.9% by mass.

[0023] 5. Examples and Comparative Examples Next, examples and comparative examples of the present invention will be described.

[0024] 5-1. Percentage of processed eggshells (1) First, we will describe Examples 1 to 6 and Comparative Examples 1 to 3, which examined the content of processed eggshells in the raw material composition.

[0025] (Example 1) Untreated eggshells with attached eggshell membranes were calcined at 600°C for 2 hours using an electric or gas furnace. This removed the eggshell membranes from the untreated eggshells. The components of the treated eggshells after calcination were analyzed using known methods and found to be CaCO3.

[0026] 1.0% by mass of processed eggshells, 15.2% by mass of limestone, 33.0% by mass of bovine bone ash, 7.7% by mass of feldspar, 9.3% by mass of kaolin, 18.1% by mass of pottery stone, and 15.7% by mass of clay were weighed and placed into a mixing device such as a trommel or ball mill. A predetermined amount of water was then added and the mixture was mixed and ground.

[0027] The slurry was removed from the mixing apparatus, and impurities, coarse particles, etc., were sieved off using a vibrating sieve.

[0028] The moisture was removed using a filter press to create a flat cake.

[0029] After adjusting the moisture content of the cake, the molded body was formed into the desired shape and dried.

[0030] The resulting molded body was heated to approximately 1250°C in an air atmosphere and subjected to oxidation firing. At this stage, test specimens were prepared for evaluation tests that would use unglazed specimens in the evaluation tests described later.

[0031] A glaze was applied to the molded body obtained by oxidation firing using a spray or the like, and then an oxidation firing was performed by heating at around 1150°C in an air atmosphere to form a glass layer on the surface of the molded body. Thus, the bone china product according to Example 1 was produced.

[0032] (Example 2) A bone china product according to Example 2 was prepared in the same manner as in Example 1, except that the amount of processed eggshells added was 5.0% by mass and the amount of limestone added was 11.2% by mass.

[0033] (Example 3) A bone china product according to Example 3 was prepared in the same manner as in Example 1, except that the amount of processed eggshells added was 10.0% by mass and the amount of limestone added was 6.2% by mass.

[0034] (Example 4) A bone china product according to Example 4 was prepared in the same manner as in Example 1, except that the amount of processed eggshells added was 16.2% by mass and the amount of limestone added was 0.0% by mass.

[0035] (Example 5) 14.7% by mass of processed eggshells, 0.0% by mass of limestone, 30.0% by mass of bovine bone ash, 7.0% by mass of feldspar, 8.5% by mass of kaolin, 16.5% by mass of pottery stone, 14.3% by mass of clay, and 9.0% by mass of recycled bone china that does not contain eggshells after firing were weighed and placed into a mixing device such as a trommel or ball mill, and a predetermined amount of water was added and the mixture was mixed and ground.

[0036] Except as described above, the bone china product according to Example 5 was prepared in the same manner as in Example 1.

[0037] (Example 6) Except for using recycled bone china made from processed eggshells as the raw material, in which all of the limestone was replaced with recycled eggshells, the bone china product according to Example 6 was prepared in the same manner as in Example 5.

[0038] (Comparative Example 1) A bone china product according to Comparative Example 1 was prepared in the same manner as in Example 1, except that the amount of processed eggshells added was 0.0% by mass and the amount of limestone added was 16.2% by mass.

[0039] (Comparative Example 2) A bone china product according to Comparative Example 2 was prepared in the same manner as in Example 1, except that the amount of eggshells with attached eggshell membranes was set to 16.2% by mass and the amount of limestone added was set to 0.0% by mass.

[0040] (Comparative Example 3) A bone china product according to Comparative Example 3 was prepared in the same manner as in Example 6, except that the amount of processed eggshells added was 0.0% by mass and the amount of limestone added was 14.7% by mass.

[0041] (2) Evaluation Test ·Transparency For Examples 1-9 and Comparative Examples 1-3, which were treated with glaze, the light transmittance was measured using an AUTOMATIC DIGITAL HAZEMETER NDH-20D manufactured by Nippon Denshoku Industries Ltd., in accordance with JIS Z 8722. The measurement results are summarized in Table 1.

[0042] • Bending strength For Examples 1-6 and Comparative Examples 1-3, the bending strength of untreated specimens was measured using an Amsler-type vertical tensile testing machine manufactured by Maekawa Testing Machine Co., Ltd., in accordance with the Japan Ceramic Society standard JCRS203-1996. The measurement results are summarized in Table 1.

[0043] ·Whiteness For Examples 1-6 and Comparative Examples 1-3, which were treated with glaze, the whiteness was measured using a Color meter ZE6000 manufactured by Nippon Denshoku Industries Ltd., in accordance with JIS Z 8722 and ASTM E 313. The measurement results are summarized in Table 1.

[0044] • Coefficient of thermal expansion For Examples 1-6 and Comparative Examples 1-3, the coefficient of thermal expansion was measured on unglazed test specimens using a Rigaku Thermo plus EV02 TMA8311 in accordance with JIS R 1618 "Method for Measuring Thermal Expansion of Fine Ceramics by Thermomechanical Analysis". The measurement results are summarized in Table 1.

[0045] • Sieve clogging For Examples 1-6 and Comparative Examples 1-3, the vibrating sieves were visually inspected to determine whether or not clogging by eggshell membrane occurred when the slurry removed from the mixing apparatus was processed using a vibrating sieve. The results are summarized in Table 1.

[0046] [Table 1]

[0047] (3) Evaluation results ·Transparency As shown in Table 1, the light transmittance of Examples 1 to 6, in which all or part of the limestone was replaced with treated eggshells, was approximately the same as that of Comparative Examples 1 and 3, which used limestone as the raw material.

[0048] • Bending strength As shown in Table 1, the flexural strength of Examples 1 to 6, in which all or part of the limestone was replaced with treated eggshells, was approximately the same as that of Comparative Examples 1 and 3, which used limestone as the raw material.

[0049] ·Whiteness As shown in Table 1, the whiteness of Examples 1-6, in which all or part of the limestone was replaced with treated eggshells, was higher than that of Comparative Examples 1 and 3, which used limestone as the raw material. This is thought to be due to the lower iron content in treated eggshells compared to limestone.

[0050] • Coefficient of thermal expansion As shown in Table 1, the thermal expansion coefficients of Examples 1 to 6, in which all or part of the limestone was replaced with treated eggshells, were approximately the same as those of Comparative Examples 1 and 3, which used limestone as the raw material.

[0051] • Sieve clogging As shown in Table 1, in Examples 1 to 6, where all or part of the limestone was replaced with treated eggshells, no clogging of the sieve due to eggshell membranes was observed. However, in Comparative Example 2, where untreated eggshells were used as the raw material, clogging of the sieve due to eggshell membranes occurred.

[0052] 5-2. Regarding firing temperature (1) Next, we will describe Examples 4, 7 to 10, and Comparative Examples 1, 4 and 5, which investigated the calcination temperature for calcining untreated eggshells.

[0053] (Example 7) A bone china product according to Example 7 was prepared in the same manner as in Example 4, except that the firing temperature of the untreated eggshells was set to 300°C and the firing time was set to 3 hours.

[0054] (Example 8) A bone china product according to Example 8 was prepared in the same manner as in Example 4, except that the firing temperature of the untreated eggshells was set to 500°C and the firing time was set to 2 hours.

[0055] (Example 9) A bone china product according to Example 8 was prepared in the same manner as in Example 4, except that the firing temperature of the untreated eggshells was set to 700°C and the firing time to 2 hours.

[0056] (Example 10) A bone china product according to Example 10 was prepared in the same manner as in Example 4, except that the firing temperature of the untreated eggshells was set to 900°C and the firing time was 1.5 hours.

[0057] (Comparative Example 4) A bone china product according to Comparative Example 4 was prepared in the same manner as in Example 4, except that the firing temperature of the untreated eggshells was set to 200°C and the firing time was set to 4 hours. In Comparative Example 4, eggshell membrane remained on the eggshells after firing.

[0058] (Comparative Example 5) Untreated eggshells were calcined at 1000°C for 1 hour to remove the eggshell membrane. Analysis of the treated eggshells after calcination, using known methods, revealed that the main component was CaO. The experiment was stopped once the component of the treated eggshells was identified as CaO.

[0059] (2) Evaluation Test ·Transparency The light transmittance was measured in the same manner as described above for Examples 4, 7-10, and Comparative Examples 1 and 4, which were treated with glaze. The measurement results are summarized in Table 2.

[0060] • Bending strength For Examples 4, 7-10, and Comparative Examples 1 and 4, the bending strength was measured in the same manner as described above for test specimens that had not been treated with glaze. The measurement results are summarized in Table 2.

[0061] ·Whiteness The whiteness of Examples 4, 7-10, and Comparative Examples 1 and 4, which were treated with glaze, was measured in the same manner as described above. The measurement results are summarized in Table 2.

[0062] • Coefficient of thermal expansion For Examples 4, 7-10, and Comparative Examples 1 and 4, the coefficient of thermal expansion was measured in the same manner as described above for test specimens that had not been treated with glaze. The measurement results are summarized in Table 2.

[0063] • Sieve clogging For Examples 4, 7-10, and Comparative Examples 1 and 4, the vibrating sieves used to process the slurry removed from the mixing apparatus were visually inspected to determine whether or not clogging by eggshell membranes occurred. The results are summarized in Table 2.

[0064] In the case of Comparative Example 5, the experiment was stopped when it was identified that the component of the treated eggshell was CaO, so the evaluation test described above was not performed.

[0065] [Table 2]

[0066] (3) Evaluation results ·Transparency As shown in Table 2, the light transmittance of Examples 4, 7-10, in which the calcination temperature of the untreated eggshells was 300-900°C, was approximately the same as that of Comparative Example 1, which used limestone as a raw material.

[0067] • Bending strength As shown in Table 2, the flexural strength of Examples 4, 7-10, in which the calcination temperature of untreated eggshells was 300-900°C, was approximately the same as that of Comparative Example 1, which used limestone as a raw material.

[0068] ·Whiteness As shown in Table 2, the whiteness of Examples 4, 7-10, in which the calcination temperature of untreated eggshells was 300-900°C, was higher than that of Comparative Example 1, which used limestone as a raw material.

[0069] • Coefficient of thermal expansion As shown in Table 2, the thermal expansion coefficients of Examples 4, 7-10, where the calcination temperature of the untreated eggshells was 300-900°C, were approximately the same as those of Comparative Example 1, which used limestone as a raw material.

[0070] • Sieve clogging As shown in Table 2, in Examples 4, 7-10, where the calcination temperature of the untreated eggshells was 300-900°C, no clogging of the sieve by eggshell membrane was observed. However, in Comparative Example 4, where the calcination temperature of the untreated eggshells was 200°C, clogging of the sieve occurred due to the remaining eggshell membrane.

[0071] 6. Effects of this form Next, the effects of this embodiment will be explained. The method for manufacturing bone china products according to this embodiment comprises: an eggshell processing step of producing processed eggshells by firing untreated eggshells with eggshell membranes attached at a temperature of 300°C to 900°C to remove the eggshell membranes from the untreated eggshells; and a preparation step of preparing a raw material composition for bone china products by mixing a CaCO3 source with materials other than the CaCO3 source, wherein in the preparation step, processed eggshells are mixed as part or all of the CaCO3 source.

[0072] This method allows for the production of processed eggshells from which the eggshell membrane attached to unprocessed eggshells has been removed. This prevents the sieves used in the process of removing impurities and coarse grains from becoming clogged with eggshell membrane, allowing the processed eggshells to be used as raw materials for bone china products. As a result, by reusing eggshells, which are food industry waste, the amount of eggshell waste can be reduced, thereby improving environmental issues.

[0073] Furthermore, when untreated eggshells are calcined at temperatures below 900°C to remove the eggshell membrane, the chemical change of CaCO3, a component of eggshells, to CaO can be suppressed. This allows treated eggshells to be used as a source of CaCO3, thereby improving the manufacturing efficiency of bone china products.

[0074] The manufacturing method for bone china products according to this embodiment is such that the processed eggshell content relative to the raw material composition is greater than 0.0% by mass and 17% by mass or less.

[0075] Bone china products contain limestone as a component of their raw material composition in a proportion of 17% by mass or less. By replacing all or part of this limestone with eggshells, the amount of eggshell waste can be reduced, thereby improving environmental issues.

[0076] Furthermore, the manufacturing method for bone china products according to this embodiment involves mixing recycled bone china in the preparation process, thereby using the Ca component (CaCO3 or CaO) contained in recycled bone china, in addition to processed eggshells, as a source of CaCO3.

[0077] Since recycled bone china contains calcium, it can be used as a source of CaCO3. By using recycled bone china as a source of CaCO3, defective bone china products that were previously discarded as waste clay can be reused, further improving environmental conditions.

[0078] Furthermore, the manufacturing method for bone china products in this form involves the production of recycled bone china using processed eggshells as a source of CaCO3.

[0079] By using processed eggshells as a source of CaCO3, a raw material for recycled bone china, environmental problems can be further improved.

[0080] The present invention is not limited to the embodiments described above, and can be applied to various embodiments without departing from its spirit.

Claims

1. An eggshell processing step involves firing untreated eggshells with the eggshell membrane attached at a temperature of 300°C to 900°C to remove the eggshell membrane from the untreated eggshells and produce treated eggshells, CaCO ３ The source of the CaCO ３ A method for manufacturing bone china products, comprising a preparation step of preparing a raw material composition for bone china products by mixing it with materials other than the source of the bone china, In the preparation step, the CaCO ３ The raw material composition is prepared by mixing the processed eggshells as part or all of the source of the raw material, and further, The process involves mixing water with the raw material composition and grinding it to prepare a slurry, A method for manufacturing bone china products, comprising the step of sieving the aforementioned slurry.

2. The method for producing a bone china product according to claim 1, wherein the content of the processed eggshells in the raw material composition is more than 0.0% by mass and 17.0% by mass or less.

3. By mixing recycled bone china in the preparation step, the CaCO2 ３ As a source of supply, in addition to the processed eggshells, CaCO3 contained in the recycled bone china ３ A method for manufacturing a bone china product according to claim 1 or 2, using [the specified method].

4. The recycled bone china is the CaCO ３ A method for manufacturing a bone china product according to claim 3, wherein the product is manufactured using the processed eggshells as a source of supply.

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