Bone china product and method for manufacturing the same

Abstract

To provide a bone china product having a uniform color, wherein an increase in manufacturing cost is suppressed.SOLUTION: A bone china product 10 includes a bone china base 11 and a coloring layer 12 arranged on a surface of the bone china base 11, wherein the coloring layer 12 comprises a pigment, a CaO component, and a P2O5 component. The CaO component in the coloring layer 12 is white. Therefore, the surface of the bone china base 11 is suppressed from being transparent through the coloring layer 12. Accordingly, the coloring layer 12 can be formed on a surface of the bone china product 10 having a uniform color with suppressed color irregularities, as if painted with opaque paints. In addition, the amount of pigment used can be reduced compared to the case where a pigment is added to a slip for the base, and thus the manufacturing cost of the bone china product 10 can be reduced.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a bone china product and a method for producing the same. [Background technology]

[0002] Conventionally, a method for coloring bone china products is known in which a pigment is added to clay to color the entire bone china body. Also, a method for coloring the bone china body is known in which, instead of coloring the bone china body, a colored glaze is applied to the surface of the bone china body. For example, a method described in Patent Document 1 is known as a method for coloring bone china products. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 58-6718 Summary of the Invention [Problem to be solved by the invention]

[0004] When the entire bone china body is colored by adding pigment to the clay, a larger amount of pigment is used than when a colored glaze is applied to the surface of the bone china body, which may increase manufacturing costs.

[0005] On the other hand, when a colored glaze is applied to the surface of bone china, the glaze becomes vitreous and transparent after firing, which means that the color and shape of the bone china are visible through the glaze, which can lead to uneven coloring of bone china products.

[0006] The present invention has been made in view of the above background, and aims to provide a bone china product having a uniform color while suppressing an increase in manufacturing costs, and a method for manufacturing a bone china product. [Means for solving the problem]

[0007] One aspect of the present invention is Bone china base and A colored layer is disposed on the surface of the bone china base. The color layer is in a bone china product, which contains a pigment, a CaO component, and a P2O5 component.

[0008] Another aspect of the present invention is A method for producing the above bone china product, comprising the steps of: a molding step of forming a bone china green body by molding the raw material composition into a predetermined shape; and a coating step of coating the surface of the bone china green body with a colored slip containing at least calcium phosphate, water, and a pigment. Effect of the Invention

[0009] In the colored layer, at least a part of the CaO component is combined with the P2O5 component to form tricalcium phosphate. Tricalcium phosphate is white, which prevents the surface of the bone china base from showing through the colored layer. This allows the surface of the bone china product to have a colored layer with a uniform color with reduced color unevenness, like painting with opaque paint.

[0010] In addition, since the pigment is contained in the colored layer, the amount of pigment used can be reduced compared to when the pigment is added to the bone china base, which can reduce the manufacturing costs of bone china products.

[0011] As described above, according to one and other aspects of the present invention, it is possible to provide bone china products with uniform color while suppressing an increase in manufacturing costs. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 shows the manufacturing process of a bone china product according to embodiment 1, in which (a) shows a bone china green base, (b) shows a colored ginger applied to the surface of the bone china green base, (c) shows a colored layer applied to the surface of the bone china base, (d) shows a glaze applied to the surface of the colored layer, and (e) shows a bone china product in which a glaze layer is applied to the surface of the colored layer. [Diagram 2] 1 is a flowchart showing a method for manufacturing a bone china product according to the first embodiment. [Diagram 3] FIG. 1 shows a manufacturing process of a bone china product according to embodiment 2, in which (a) shows a bone china green base, (b) shows a colored ginger applied to the surface of the bone china green base, (c) shows a colored layer applied to the surface of the bone china base, (d) shows a glaze applied to the surface of the colored layer, and (e) shows a bone china product in which a glaze layer is applied to the surface of the colored layer. [Figure 4] FIG. 11 is a diagram showing the manufacturing process of a bone china product according to embodiment 3, in which (a) shows a state in which the colored slip applied to the surface of the bone china green body has been masked, (b) shows a state in which the colored slip has been peeled off by blasting to expose the bone china green body, (c) shows a state in which a colored layer has been applied to the surface of the bone china body and the bone china body is exposed in the exposed portion, (d) shows a state in which glaze has been applied to the surface of the colored layer and the surface of the exposed portion, and (e) shows a bone china product in which a glaze layer has been applied to the surface of the colored layer and the surface of the exposed portion. [Diagram 5] 10 is a flowchart showing a method for manufacturing a bone china product according to a third embodiment. [Figure 6] FIG. 1 shows the manufacturing process of bone china products according to comparative examples, where (a) shows the process of attaching transfer paper to the glaze layer formed on the surface of the bone china base according to comparative example 1, and (b) shows the process of attaching transfer paper to the surface of the bone china base according to comparative example 2. [Figure 7]1A and 1B are diagrams showing bone china products according to comparative examples, where FIG. 1A is a diagram showing a bone china product according to comparative example 3, and FIG. 1B is a diagram showing a bone china product according to comparative example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (Embodiment 1) 1-1 Composition of 10 bone china products A first embodiment of the present invention will be described with reference to Fig. 1. As shown in Fig. 1(e), a bone china product 10 according to this embodiment includes a bone china base 11, a colored layer 12 formed on the surface of the bone china base 11, and a glaze layer 13 formed on the surface of the colored layer 12.

[0014] According to JIS (Japanese Industrial Standards) S2401:1991, the bone china product 10 is defined as "a base material consisting of at least tricalcium phosphate, anorthite, and vitreous matter." It also states that "the tricalcium phosphate content must be 30% by mass or more." For ease of explanation, the thickness of the colored layer 12 and the thickness of the glaze layer 13 are exaggerated. In other drawings, the thickness of the layers constituting the bone china product 10 may be exaggerated even if not otherwise specified.

[0015] For example, bone ash, limestone, feldspar, kaolin, pottery stone, and clay can be used as the raw material of the bone china body 11. For example, cow bone ash can be used as the bone ash, but bone ash of other living things such as birds and fish can also be used.

[0016] The colored layer 12 may be formed on the entire surface of the bone china base 11, or may be formed on a part of the surface of the bone china product 10. The colored layer 12 contains a pigment, a CaO component, and a P2O5 component. There are no particular limitations on the pigment, and commercially available pigments can be used. The CaO component and the P2O5 component can be identified by subjecting the colored layer 12 to a component analysis using a known method.

[0017] The colored layer 12 may be one layer or two or more layers. By adjusting the number of the colored layers 12, it is possible to express a variety of shades of color.

[0018] The colored layer 12 is formed by firing a colored slip 12a containing a pigment and bone ash. The P2O5 component contained in the colored layer 12 originates from the bone ash contained in the colored slip 12a.

[0019] In the colored layer 12, at least a portion of the CaO component is combined with the P2O5 component to form tricalcium phosphate. Tricalcium phosphate is white, which prevents the surface of the bone china base material 11 from showing through the colored layer 12. This allows the colored layer 12 to be formed on the surface of the bone china product 10 with a uniform color with reduced color unevenness, as if it were painted with an opaque paint.

[0020] Furthermore, according to this embodiment, the amount of pigment used can be reduced compared to when a pigment is added to the bone china base 11, so that the manufacturing cost of the bone china product 10 can be reduced.

[0021] The content of the P2O5 component in the colored layer 12 is preferably 13.5 mass % or more. According to JIS S2401:1991, the content of tricalcium phosphate is calculated by the following formula (1). Tricalcium phosphate (%) = 2.183 × phosphorus pentoxide content (%) … (1)

[0022] According to the above formula (1), when the content of the P2O5 component in the colored layer 12 is 13.5 mass% or more, the content of tricalcium phosphate in the colored layer 12 is about 30 mass% or more. That is, the colored layer 12 can substantially meet the standard of the bone china product 10 in JIS S2401:1991. "Substantially meets" includes the case where the colored layer 12 meets the standard of the bone china product 10, and also includes the case where the colored layer 12 can be recognized as substantially meeting the standard even if it does not meet the standard. This reduces the burden of adjusting the amount of addition of the colored layer 12 so that the total content of tricalcium phosphate in the finished bone china product 10 meets JIS S2401:1991. As a result, the manufacturing process of the bone china product 10 can be labor-saving. However, the content of tricalcium phosphate in the colored layer 12 may be less than 30 mass%.

[0023] The content of the pigment in the colored layer 12 is preferably 5 to 95% by mass, which allows the colored layer 12 to have excellent color development properties.

[0024] The colored layer 12 preferably contains 8-31 mass% SiO2, 0.1-0.2 mass% TiO2, 6-14 mass% Al2O3, 0.2-0.3 mass% Fe2O3, 13-19 mass% P2O5, 18-25 mass% CaO, 0.1-0.2 mass% MgO, 0.1-1.7 mass% K2O, and 0.1-0.5 mass% Na2O. This allows the composition of the colored layer 12 to be closer to the composition of the bone china base 11. As a result, the colored layer 12 itself can be given an aesthetic appearance similar to that of the bone china product 10.

[0025] 1-2 Manufacturing methods for bone china products 10 Next, an example of a method for manufacturing the bone china product 10 according to the present embodiment will be described with reference to Figures 1 and 2. However, the method for manufacturing the bone china product 10 is not limited to the following description.

[0026] Fig. 2 shows a flow chart of the manufacturing process of the bone china product 10 according to this embodiment. First, a predetermined amount of raw materials for the bone china base 11 is blended and mixed with water. Then, as shown in Fig. 1(a), the raw bone china base 11a is formed into a predetermined shape and dried (S1, an example of a molding process).

[0027] Next, a predetermined amount of raw materials for the colored slip 12a is blended and mixed with water to prepare the colored slip 12a. The colored slip 12a thus prepared is applied to the surface of the bone china green body 11a as shown in FIG. 1(b) (S2, an example of a coating process).

[0028] The colored slip 12a may be applied to the surface of the bone china green body 11a by using a spray, or may be applied by dipping the bone china green body 11a in the colored slip 12a. The method of applying the colored slip 12a is not limited to the above, and any method, such as application by a brush, may be appropriately selected.

[0029] Next, the bone china green body 11a coated with the colored slip 12a is dried and then baked at a temperature of 1200° C. to 1300° C. (S3), forming a colored layer 12 on the surface of the bone china body 11 as shown in FIG.

[0030] Next, as shown in Fig. 1(d), the bone china base 11 on which the colored layer 12 is formed is glazed with a glaze 13a (S4). The glaze 13a may be applied by spraying, or may be applied by dipping into the glaze 13a. The method of applying the glaze 13a is not particularly limited.

[0031] Next, the product is glaze-fired at 1100°C to 1200°C (S5). As a result, as shown in Fig. 1(e), a bone china product 10 is completed, which includes a bone china base 11, a colored layer 12 formed on the surface of the bone china base 11, and a glaze layer 13 formed on the surface of the colored layer 12. In this embodiment, two firing steps, namely, dark firing and glaze firing, are performed before the bone china product 10 decorated with the colored layer 12 is completed.

[0032] (Embodiment 2) 2-1 Composition of 10 bone china products Next, a bone china product 10 according to a second embodiment will be described with reference to FIG. 3. As shown in FIG. 3(e), a recess 14 recessed from a reference surface 11b is formed on the surface of the bone china base 11 of this embodiment. As a result, a step portion 15 is formed between the reference surface 11b of the bone china base 11 and the bottom surface of the recess 14. The surface of the bone china base 11 described above includes the reference surface 11b of the bone china base 11, the bottom surface of the recess 14, and the step portion 15. However, the step portion 15 may be formed by forming a protrusion on the surface of the bone china base 11. The step portion 15 may also be formed by forming both the recess 14 and the protrusion on the reference surface 11b of the bone china base 11.

[0033] 3(e), the thickness of the colored layer 12 formed on the surface of the bone china base 11 is thinner at the boundary portion 16 between the reference surface 11b of the bone china base 11 and the step portion 15 than at other portions. For this reason, it is thought that the color (white) of the bone china base 11 shows through in the portion of the colored layer 12 that is thinner than the other portions.

[0034] Regarding the above points, the colored layer 12 of this embodiment contains tricalcium phosphate derived from a CaO component and a P2O5 component. Because tricalcium phosphate is white, the color of the bone china base material 11 is prevented from showing through the colored layer 12. This allows the colored layer 12 to be formed on the surface of the bone china base material 11 with a uniform color with reduced color unevenness.

[0035] In addition, among the symbols used in the second and subsequent embodiments, the same symbols as those used in the previous embodiments represent the same components, etc. as those in the previous embodiments, unless otherwise specified.

[0036] 2-2 Manufacturing methods for bone china products 10 Next, an example of a method for manufacturing the bone china product 10 according to this embodiment will be described with reference to Fig. 3. However, the method for manufacturing the bone china product 10 is not limited to the following description. Note that the flow chart of the method for manufacturing the bone china product 10 according to this embodiment is the same as that of the first embodiment, so a detailed description will be omitted.

[0037] In this embodiment, as shown in FIG. 3(a), in the step of molding the bone china green body 11a (S1 in FIG. 2), recesses 14 are formed on the surface of the bone china green body 11a.

[0038] Next, as shown in Fig. 3(b), a colored slip 12a is applied to the surface of the bone china base material 11 (S2 in Fig. 2). The thickness of the colored slip 12a is thinner at a boundary portion 16 between the surface of the bone china base material 11 and the step portion 15 than at other portions.

[0039] Next, biscuit firing is carried out (S3 in FIG. 2), which forms a colored layer 12 on the surface of the bone china base 11, as shown in FIG. 3(c).

[0040] Next, as shown in FIG. 3(d), a glaze 13a is applied to the surface of the colored layer 12 (S4 in FIG. 2).

[0041] Next, glaze firing is performed (S5 in FIG. 2), thereby completing a bone china product 10 having a bone china base 11, a colored layer 12 formed on the surface of the bone china base 11, and a glaze layer 13 formed on the surface of the colored layer 12, as shown in FIG. 3(e).

[0042] (Embodiment 3) 3-1 Composition of 10 bone china products Next, a bone china product 10 according to a third embodiment will be described with reference to Fig. 4. As shown in Fig. 4(c), the surface of the bone china base 11 of this embodiment has an exposed portion 17 where the surface of the bone china base 11 is exposed because the colored layer 12 is not arranged. This allows the bone china product 10 to be decorated by the color of the colored layer 12 and the white color of the bone china base 11.

[0043] Furthermore, in the bone china product 10 of this embodiment, a glaze layer 13 is formed on the surface of the exposed portion 17, as shown in FIG. 4(e).

[0044] 3-2 Manufacturing methods for bone china products 10 Next, an example of a method for manufacturing the bone china product 10 according to this embodiment will be described with reference to Figures 4 and 5. However, the method for manufacturing the bone china product 10 is not limited to the following description.

[0045] As shown in Fig. 5, a bone china green body 11a is molded (S1), and a colored slip 12a is applied to the surface of the bone china green body 11a (S2). S1 and S2 are the same as S1 and S2 in the first embodiment, so a duplicated description will be omitted.

[0046] Next, after the applied colored slip 12a is dried, a masking step is carried out in which masking tape 20 is applied to predetermined areas as shown in FIG. 4(a) (S11 in FIG. 5).

[0047] Next, blasting is performed (S12 in FIG. 5). This scrapes off the colored slip 12a from the portion where the masking tape 20 is not attached (see FIG. 4(b)). The particles used in the blasting are not particularly limited, and any particles such as metal powder, sand, walnut shells, etc. can be appropriately selected.

[0048] Next, after removing the masking tape 20, the product is dark-fired (see S3 in FIG. 5 and FIG. 4(c)). After that, the glaze 13a is applied (see S4 in FIG. 5 and FIG. 4(d)), and the product is glaze-fired (see S5 in FIG. 5 and FIG. 4(e)). The steps S3 to S5 are the same as those in the first embodiment, so the repeated explanations will be omitted.

[0049] Example 1 Next, Example 1 of the present invention will be described. First, a slurry for forming a bone china body 11 was prepared. 33.0 parts by mass of bone ash, 16.2 parts by mass of limestone, 25.0 parts by mass of clay, 7.7 parts by mass of feldspar, and 18.1 parts by mass of pottery stone were put into a mixing device such as a trommel or a ball mill, and a predetermined amount of water was added to mix and grind. The raw material composition of the slurry for the body is summarized in Table 1.

[0050] The base slurry was taken out of the mixer and impurities, coarse particles, etc. were removed using a vibrating sieve.

[0051] The water was removed using a filter press to form a plate-like cake.

[0052] After adjusting the moisture content of the cake, the bone china green body 11a was formed into a shape having recesses 14 on the surface, and then dried.

[0053] Next, colored slip 12a was prepared. 29.7 parts by weight of bone ash, 14.6 parts by weight of limestone, 22.5 parts by weight of clay, 6.9 parts by weight of feldspar, 16.3 parts by weight of pottery stone, and 10.0 parts by weight of pigment were put into a mixing device such as a trommel or a ball mill, and a predetermined amount of water was added and mixed and crushed. In this way, colored slip 12a was prepared. The raw material composition of colored slip 12a is summarized in Table 2.

[0054] A colored slip 12a was applied to the surface of the bone china green body 11a by spraying. After drying, the body was heated to 1250° C. in an air atmosphere and baked. As a result, a colored layer 12 was formed on the surface of the bone china body 11.

[0055] A glaze 13a was applied by spraying to the colored layer 12 formed on the surface of the bone china base 11. Next, the product was heated at 1150°C in an air atmosphere to perform oxidation firing, thereby forming a glaze layer 13 on the surface of the colored layer 12. In this manner, the bone china product 10 according to Example 1 was produced. The bone china product 10 of Example 1 has the configuration shown in Fig. 1(e).

[0056] A component analysis was performed by a known method on the bone china product 10 of Example 1. The composition of the bone china base 11 of the bone china product 10 is summarized in Table 1. The tricalcium phosphate content in the bone china base 11 is also summarized in Table 1. The tricalcium phosphate content was calculated from the P2O5 content in the bone china base 11 based on formula (1) according to JIS S2401:1991.

[0057] The composition of the colored layer 12 of the bone china product 10 is summarized in Table 2. The content of tricalcium phosphate in the colored layer 12 is also summarized in Table 2. The content of tricalcium phosphate was calculated from the content of P2O5 in the colored layer 12 based on formula (1) according to JIS S2401:1991.

[0058] [Table 1]

[0059] [Table 2]

[0060] (Embodiment 2) Next, Example 2 will be described. A bone china product 10 according to Example 2 was produced in the same manner as Example 1, except that the colored slip 12a was prepared with the raw material composition shown in Table 2. The bone china product 10 was subjected to component analysis in the same manner as Example 1, and the results are summarized in Tables 1 and 2.

[0061] As shown in Table 2, the pigment composition in the colored slip 12a of Example 2 is 31.0 parts by mass, which is higher than the 10.9 parts by mass in Example 1. The colored slip 12a of Example 2 has a higher pigment composition ratio without changing the relative composition ratios of bone ash, limestone, clay, feldspar, and pottery stone in the colored slip 12a of Example 1. The pigment composition ratio was adjusted so that the tricalcium phosphate content in the colored layer 12 was 30% by mass.

[0062] Example 3 Next, Example 3 will be described. A bone china product 10 according to Example 3 was produced in the same manner as Example 1, except that the colored slip 12a was prepared with the raw material composition shown in Table 2. The bone china product 10 was subjected to component analysis in the same manner as Example 1, and the results are summarized in Tables 1 and 2.

[0063] As shown in Table 2, the pigment composition in the colored slip 12a of Example 3 was 43.4 parts by mass. The colored slip 12a of Example 3 was obtained by replacing the pottery stone composition with a pigment, without changing the relative proportions of bone ash, limestone, clay, and feldspar in the colored slip 12a of Example 2. The pigment composition was adjusted so that the tricalcium phosphate content in the colored layer 12 was 30% by mass.

[0064] Example 4 Next, Example 4 will be described. A bone china product 10 according to Example 4 was produced in the same manner as Example 1, except that the colored slip 12a was prepared with the raw material composition shown in Table 2. The bone china product 10 was subjected to component analysis in the same manner as Example 1, and the results are summarized in Tables 1 and 2.

[0065] As shown in Table 2, the pigment composition in the colored slip 12a of Example 4 was 48.6 parts by mass. The colored slip 12a of Example 4 was obtained by replacing the feldspar and pottery stone composition with pigments without changing the relative proportions of bone ash, limestone, and clay in the colored slip 12a of Example 2. The pigment composition was adjusted so that the tricalcium phosphate content in the colored layer 12 was 30% by mass.

[0066] Example 5 Next, Example 5 will be described. A bone china product 10 according to Example 5 was produced in the same manner as Example 1, except that the colored slip 12a was prepared with the raw material composition shown in Table 2. The bone china product 10 was subjected to component analysis in the same manner as Example 1, and the results are summarized in Tables 1 and 2.

[0067] As shown in Table 2, the pigment composition in the colored slip 12a of Example 5 is 65.1 parts by mass. The colored slip 12a of Example 5 is the same as the colored slip 12a of Example 2, except that the clay, feldspar, and pottery stone are replaced with pigments, while the relative proportions of bone ash and limestone are not changed. The pigment composition was adjusted so that the tricalcium phosphate content in the colored layer 12 was 30% by mass.

[0068] Comparative Example 1 Next, a description will be given of Comparative Example 1. A bone china body 11 was produced in the same manner as in Example 1. The raw material composition of the body slurry of the bone china body 11 is summarized in Table 1.

[0069] Next, a glaze 13a was applied to the surface of the bone china base 11, and the glaze layer 13 was formed by firing the glaze.

[0070] Next, as shown in FIG. 6(a), a transfer paper 30 moistened with water was placed on the glaze layer 13 as indicated by the arrow A, and an attempt was made to attach it to the surface of the glaze layer 13. A glaze-side recess 14a was formed on the surface of the glaze layer 13 at a position overlapping with the recess 14 formed on the surface of the bone china base 11. Air remained between the glaze-side recess 14a and the transfer paper 30, making it impossible to remove the air without tearing the transfer paper 30. For this reason, in Comparative Example 1, decoration using the transfer paper 30 was not possible.

[0071] Comparative Example 2 Next, a description will be given of Comparative Example 2. A bone china body 11 was produced in the same manner as in Example 1. The raw material composition of the body slurry of the bone china body 11 is summarized in Table 1.

[0072] Next, as shown in FIG. 6(b), as indicated by the arrow B, a transfer paper 30 moistened with water was placed on the surface of the bone china base 11, and an attempt was made to attach it to the surface of the bone china base 11. Air remained between the depressions 14 formed on the surface of the bone china base 11 of Comparative Example 1 and the transfer paper 30. It was impossible to remove the air without tearing the transfer paper 30. For this reason, in Comparative Example 2, decoration using the transfer paper 30 was not possible.

[0073] Comparative Example 3 Next, a description will be given of Comparative Example 3. A bone china body 11 was produced in the same manner as in Example 1. The raw material composition of the body slurry of the bone china body 11 is summarized in Table 1.

[0074] Next, a pigment was mixed into the glaze 13a to prepare a colored glaze colored with the pigment. The content of the pigment was 10 parts by mass relative to the glaze 13a. Then, the colored glaze was applied to the surface of the bone china base 11, and the glaze was fired to form a colored glaze layer 13b, as shown in FIG. 7(a).

[0075] The bone china product 10 according to Comparative Example 3 has a colored glaze layer 13b on the surface of the bone china base 11.

[0076] Comparative Example 4 Next, Comparative Example 4 will be described. A base slurry for forming the bone china base 11 according to Comparative Example 4 was prepared. 29.7 parts by mass of cow bone ash, 14.6 parts by mass of limestone, 22.5 parts by mass of clay, 6.9 parts by mass of feldspar, 16.3 parts by mass of pottery stone, and 10.0 parts by mass of pigment were put into a mixing device such as a trommel or a ball mill, and a predetermined amount of water was added to mix and grind. As described above, the bone china product 10 according to Comparative Example 4 includes a colored bone china base 11c, which is a bone china base 11 colored by a pigment (see FIG. 7(b)). The raw material composition of the base slurry is summarized in Table 1.

[0077] Next, a glaze 13a was applied to the surface of the colored bone china base 11c, and the glaze layer 13 was formed by firing the glaze.

[0078] (10 characteristics of bone china products) Next, the characteristics of the bone china products 10 according to the first to fifth embodiments and the first to fourth comparative examples are summarized in Table 3.

[0079] [Table 3]

[0080] (Decorating the stepped portion 15) For embodiments 1 to 5 and comparative examples 3 and 4, the portions where recesses 14 were formed in the bone china base material 11 were visually inspected to confirm whether a colored layer 12 of uniform color tone was formed on the bone china product 10. The results are summarized in Table 3. Note that in comparative examples 1 and 2, decoration with transfer paper 30 was not possible, so it was impossible to even examine the uniformity of color tone.

[0081] (About translucency) The translucency was judged by visual observation for Examples 1 to 5 and Comparative Examples 1 to 4. For Embodiments 1 to 5 and Comparative Examples 1 to 3, translucency was observed in the decorated and undecorated areas. However, for Comparative Example 4, no translucency was observed. The results are summarized in Table 3.

[0082] (L * , a * , and b * About In Example 1 and Comparative Examples 3 to 4, a sample for color measurement was prepared by adding 10% by mass of a black pigment (M-840 Black manufactured by Nitto Pigment Co., Ltd.). The lightness L of this sample was measured according to JIS 8781-4:2013. * , hue a * , hue b * The results are summarized in Table 3.

[0083] (result) As shown in Table 2, the content of tricalcium phosphate in the colored layer 12 in Examples 1 to 5 was 30 mass% or more. In other words, the colored layer 12 can satisfy the standard for bone china products 10 in JIS S2401:1991. This makes it unnecessary to adjust the amount of P2O5 added to the colored layer 12 so that the overall content of the P2O5 component in the finished bone china product 10 satisfies JIS S2401:1991. As a result, the manufacturing process for the bone china product 10 can be made more efficient.

[0084] As shown in Table 3, in the bone china products 10 according to the first to fifth embodiments, the colored layer 12 in the recesses 14 was formed with a uniform color tone without color unevenness.

[0085] On the other hand, in Comparative Examples 1 and 2, decoration using the transfer paper 30 was not performed.

[0086] In Comparative Example 3, as shown in Fig. 7(a), the colored glaze layer 13b had a thin portion at the boundary portion 16 between the reference surface 11b of the bone china body 11 and the step portion 15, and the bone china body 11 was visible through this portion. This caused color unevenness in the colored glaze layer 13b.

[0087] In Comparative Example 4, since the colored bone china base 11c was colored, no color unevenness occurred in the recesses 14. However, as shown in Table 1, the pigment content in the raw material blend of the base slurry forming the colored bone china base 11c was 10 parts by mass, which increased the manufacturing cost.

[0088] In contrast, the bone china products 10 according to Examples 1 to 5 have a colored layer 12 formed on the surface of the bone china base material 11, and the colored layer 12 contains a pigment. Therefore, according to Examples 1 to 5, it is possible to obtain bone china products 10 having a colored layer 12 with a uniform color tone while suppressing the manufacturing cost.

[0089] Furthermore, as shown in Table 3, the bone china products 10 of Examples 1 to 5 have translucency.

[0090] On the other hand, although the bone china products 10 of Comparative Examples 1 and 2 also had translucency, it was impossible to attach the transfer paper 30 to the recesses 14 of the bone china base material 11 in Comparative Examples 1 and 2.

[0091] Moreover, the bone china product 10 of Comparative Example 3 also had translucency, but in Comparative Example 3, color unevenness occurred in the recesses 14 of the bone china base 11.

[0092] Moreover, the bone china product 10 of Comparative Example 4 did not have translucency because the colored bone china base 11c itself was colored.

[0093] Furthermore, as shown in Table 3, the number of firings required until the decoration was completed was two for Examples 1 to 5: dark firing and glaze firing.

[0094] On the other hand, in the case of Comparative Examples 1 and 2, in addition to the dark firing and glaze firing, an additional firing is required to bake the transfer paper 30, so three firings are required, which is not preferable since it increases the manufacturing cost.

[0095] On the other hand, in Comparative Examples 3 and 4, the number of firings is two, namely dark firing and glaze firing. However, as described above, Comparative Example 3 has color unevenness, and Comparative Example 4 increases the manufacturing cost, which are not preferable.

[0096] In addition, as shown in Table 3, in the bone china product 10 of Example 1, L * is 14.1, and a * is 2.2, and b * On the other hand, in the bone china product 10 of Comparative Example 3, L * is 13.9, and a * is 1.3, and b * In the bone china product 10 of Comparative Example 4, L * is 14.2, and a * is 2.4, and b * was 0.9. Thus, it was found that the bone china product 10 of Example 1 was capable of expressing colors at a level equivalent to other decoration methods.

[0097] The present invention is not limited to the above-described embodiments, and can be applied to various embodiments without departing from the gist of the present invention.

[0098] In the third embodiment, the step of scraping off the colored slip 12a in a predetermined area is not limited to blast processing, and for example, the colored slip 12a may be scraped off using a tool such as a blade or a spatula. [Explanation of symbols]

[0099] 10: bone china product, 11: bone china base, 12: colored layer, 13: glaze layer, 13a: glaze, 14: recess, 15: step, 16: boundary, 17: exposed area

Claims

1. Bone china base and A colored layer is disposed on the surface of the bone china base. The colored layer is made of a pigment, a CaO component, and a P ２ O ５ Ingredients and, including, bone china products.

2. The P in the colored layer ２ O ５ 2. The bone china product according to claim 1, wherein the content of the component is 13.5% by mass or more.

3. 2. The bone china product according to claim 1, wherein the content of the pigment in the colored layer is 5 to 95% by mass.

4. The colored layer is SiO ２ 8 to 31 mass %, TiO ２ 0.1 to 0.2 mass% of Al ２ O ３ 6 to 14 mass% Fe ２ O ３ 0.2 to 0.3 mass% of P ２ O ５ 13 to 19 mass%, CaO 18 to 25 mass%, MgO 0.1 to 0.2 mass%, K ２ O 0.1 to 1.7 mass%, Na ２ The bone china product according to claim 1, containing 0.1 to 0.5 mass % of O.

5. 2. The bone china product according to claim 1, wherein a step portion formed in a concave or convex shape is formed on the surface of the bone china base, and the step portion is covered with the colored layer.

6. 2. The bone china product according to claim 1, wherein the bone china base has an exposed portion where the surface of the bone china base is exposed due to the absence of the colored layer.

7. A method for producing a bone china product according to any one of claims 1 to 6, comprising the steps of: a molding step of forming a bone china green body by molding the raw material composition into a predetermined shape; A method for manufacturing a bone china product, comprising a coating step of coating a colored slip containing at least calcium phosphate, water, and a pigment on the surface of the bone china green body.

8. 8. The method for producing a bone china product according to claim 7, wherein the coating step is a step of spraying the colored slip onto the surface of the bone china green body, or a step of dipping the bone china green body into the colored slip.

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