JPH02164764A - Sintered soft porcelain body and production thereof - Google Patents

Abstract

PURPOSE:To obtain a sintered soft porcelain body which has elegant translucency and is whitish at low cost by sintering a molded body which has composition incorporating SiC2, Al2O3, CaO, P2O5, K2O, Fe2O3 and TiO2, etc., at the specified weight ratio at prescribed temp. in the oxidative atmosphere. CONSTITUTION:Raw materials such as feldspar, limestone, clay, kaolin, sericite and silica stone are mixed. A mixture is produced which has composition of by weight % 55-48% SiO2, 25-20% Al2O3, 18-12% CaO, 9-5% P2O5, 4-2% K2O and 2-0.1% (Na2O+MgO), 1-0.2% Fe2O3 and 0.7-1% TiO2 which are the impurities mixed from the used raw materials. Then a sintered soft porcelain body incorporating gray feldspar as main constitutional mineral is obtained by grinding, kneading and molding the mixture and thereafter sintering this molded body at 1150-1250 deg.C sintering temp. in the oxidative atmosphere. Thereby this sintered soft porcelain body can be produced at low cost industrially and easily because bone ash, etc., expensive in a price are not utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a white soft porcelain sintered body with elegant translucency and a method for manufacturing the same.

[Prior Art] Bone porcelain is a representative example of white soft porcelain with elegant translucency. This bone ash porcelain has 20-60% bone ash.
Kaolin 15-45%, feldspar 8-22%, silica θ-20
%, pottery stone θ~30%. Also,
Special Publication No. 46-28404 proposes bone ash porcelain using a manufacturing method that uses calcined dicalcium phosphate, which is produced by calcining dicalcium phosphate, which is produced as a by-product when refining gelatin from cow bones, instead of bone ash made from calcined beef bones. is being done. Furthermore, in Tokuko Sho 55-29956, β-pyrophosphate lime was 15 to 28% by weight, and limestone was 6 to 18% by weight.
%, sericite 5-15%, kaolin 20-40%, feldspar 5-20%, and silica stone 1-15%, that is, with a reduced amount of β-pyrophosphate lime, it is white and elegantly translucent. There is a proposal for a method of manufacturing soft porcelain that has

As an elegant translucent white porcelain that is not bone porcelain, the weight percentage is SiO□6g, 62, TiO□0.10.
Al□0゜24.9, Fe2O30,18, CaOO,
79, Mg00.74, K2O2,86, Na2O1,
There is commercially available porcelain with chemical components of 19, P2O50,61, and its constituent minerals are quartz, mullite and glass. Here, in order to obtain a white color with elegant translucency, it is necessary to minimize the amount of Fe20g and TiO2 that are mainly mixed as impurities in the natural raw materials kaolin and frog's eye clay.

However, these raw materials are commonly required by consumers and are scarce in terms of resources, making them expensive.

[Problem to be Solved by the Invention 1 Bone ash or β-pyrophosphate lime, which is the main raw material for conventional bone porcelain, is expensive. In addition, the production of bone china is said to require advanced manufacturing technology;
One is that the amount of non-plastic raw materials is increasing, and on the other hand, there are fewer machines using plastic clay, which makes the moldability of the vessels poor.The second is that the softening of the vessels is rapid due to a slight increase in the firing temperature. It is difficult to sinter while maintaining the shape.

In addition to the above-mentioned problems, component systems other than bone porcelain have a relatively small coefficient of thermal expansion of around 5.4Xl0-6 due to the constituent minerals being quartz-mullite. The range of choices is narrow, and even if the base material itself is heat resistant, when it is made into a glazed product, the heat resistance deteriorates.

The object of the present invention is to improve the conventional problems and provide a white soft porcelain sintered body with elegant translucency comparable to that of bone porcelain, and a method for manufacturing the same.

[Means for Solving the Problem] - In order to achieve the above object, the first invention of the present invention has the following features:
%SiO2.55.00~48. OO%, Al2O
325,00~20.00%, CaO1g, 00~12
．． 00%, P2O59,00-5.00%, K2O4,
00 to 2.00%, and the content of Na2O and MgO mixed from the raw materials used as impurities is 2.00 to 010%,
Fe2O3 1,00””-0,20% and TiO20
, 70 to 0.10% of chemical components, and is a soft porcelain sintered body whose main constituent mineral is anorthite.

The second invention is the manufacturing method of the first invention, in which the soft porcelain molded body is placed in an oxidizing atmosphere and at a firing temperature of 1150 to 1250°.
This is a method for producing a soft porcelain sintered body characterized by sintering with C.

[Operation] The structure of the first invention is that the main chemical components are SiO□, A1
200 and CaO can be mainly obtained from limestone, kaolin, and needle clay, so it is extremely suitable for moldability of pottery, and furthermore, it is possible to synthesize homogeneous and fine crystal anorthite using these materials. can. This provides excellent translucency.

The P2O component has the effect of suppressing undesirable color development due to Fe2O3 during oxidation firing, and if it is less than 5%, the light transmittance will be poor. If the amount exceeds 9%, the cost of raw materials will increase. As this raw material, in addition to bone ash, β-pyrophosphate lime, etc., defective bone porcelain (hereinafter referred to as Cerben), which has been produced in large quantities in recent years, may be used.

Na2O, which is mixed in as an impurity from the raw materials used, is mainly contained in feldspar, which is the raw material for Ni-20, and is also contained in sericite and chinastone, which are used as substitutes for kaolin.

MgO is mixed in from kaolin, phlegm, etc.

Fe2O3 is mainly contained in kaolin, which is an essential raw material that imparts plasticity, and frog's eye clay, but is also contained in other materials such as feldspar, sericite, and pottery stone. It is extremely difficult to reduce this to less than 0.20%.

If the amount increases and exceeds 1,00%, the whiteness will decrease.

Ti[]2 contains a large amount of kaolin, which is an essential raw material that imparts plasticity, and frog's eye clay, at 0.70%.
If the content exceeds 0.05%, an undesirable coloration will occur, and it is difficult to select a raw material with a content of less than 0.05%.

The second invention uses oxidation firing, which has good fuel efficiency, instead of reduction firing, which has poor fuel efficiency, and the firing temperature is relatively low, resulting in low fuel costs.

Next, an example will be described.

[Example 1] The weight proportions of the mixture of raw materials are as follows.

Frog-eye clay...6%, Kaolin...30%, Limestone...
・10%, sericite...10%, silica...10%,
Feldspar: 15%, β-pyrophosphate lime: 9%, Cerbene: 10%. The weight percentages of the main chemical components of the fired body of the above distribution are as shown in Table 1.

Other components in Table 1 are TiO20.10%, Fe2Q10.2
0%, MgOO, 11%, Na2O0, 69%.

The above mixture was pulverized, kneaded, and molded by a general method for manufacturing soft porcelain for tableware, and then fired at 1230° C. to obtain a sintered body.

The mineral composition of this sintered body, as shown in the X-ray chart in Figure 1, is anorthite (CaAl□5t20B>40%, tricalcium phosphate (Ca-4P207) 7%, and quartz (5iO2) 6% as other minerals. , vitreous 47%
It consists of

The quality characteristics of this sintered body are shown in Table 2.

Table 2 Transmittance was measured with a digital turbidity meter (manufactured by Nippon Heavy Industries), and whiteness was measured with a color difference meter (manufactured by Nippon Heavy Industries). The bending strength is measured using the three-point method.

The values of commercially available bone porcelain vary widely depending on the manufacturer, but the transmittance is 12 to 16", and the whiteness is 85 to 9.
3. The bending strength is in the range of 1050 to 1300, and the quality of this example is good.

Another feature of this sintered body is that it has an appropriate coefficient of thermal expansion.The product is made by applying a frit-like glaze and firing it, but in order to make the glaze compatible, thermal expansion is required. The coefficient is 5. Although OX 10-6 or more is desirable, this was 5.9 Xl0-6. Therefore, heat resistance can be further improved by applying glaze. The thermal 1fi'J coefficient of the bone porcelain base is 8.0 to 9, about OX10-6, and it has excellent heat resistance.

In addition, since the softening property of firing is glassy and has high viscosity, the shape retention of the molded product during firing is good, that is, a constant width,
When molded articles of different lengths and thicknesses were sintered at the respective sintering temperatures, the degree of softening was 0.5/1 for this example/bone porcelain, and the shape retention of this example was twice as good.

[Example 2] The weight proportions of the mixture of raw materials are as follows.

Frog-eye clay...13%, Kaolin...30%, Limestone...17%, Sericite...16%, Feldspar...7
%, β-pyrophosphate lime...12%, pottery stone...5%.

Table 3 shows the weight percentages of the main chemical components of the fired products of the above formulations.

Other components in Table 3 are TiO20.13%, Fe2O,0.2
8%, Mg 00.12%, Na2O 0.34%.

Since the manufacturing method was the same as in Example 1, only the differences will be described, except that the firing temperature was 1200°C.

The quality characteristics were good as shown in Table 4.

(Margin below) Table 4 The coefficient of thermal expansion was 5.9X10-'.

[Example 3] The weight proportions of the mixture of raw materials are as follows.

Frog-eye clay...6%, Kaolin...30%, Limestone...
...10%, sericite...10%, silica 10%, feldspar...15%, β-birophosphate lime...9%, sericite...10%.

Table 5 shows the weight percentages of the main chemical components of the fired bodies of the above formulations.

Other components in Table 5 are TiO20.12%, Fe20s 0.
51%, Mg 0.19%, Na2O 0.57%.

Since the manufacturing method was the same as in Example 1, only the differences will be described, except that the firing temperature was 1230'c.

The quality characteristics were good as shown in Table 3.

Table 6 The coefficient of thermal expansion is 6. It was OXl0-'.

[Example 4] The weight proportions of the mixture of raw materials are as follows.

Frog-eye clay...6%, Kaolin...30%, Limestone...
...10%, sericite...10%, silica...10
%, feldspar...10%, β-birophosphate lime...9%
, Cerben...10%, pottery stone...5%.

Table 7 shows the weight percentages of the main chemical components of the fired product of the above blend.

(Left below) Other ingredients in Table 7 are TiO20.09%, Fe2O30.2
3%, MgO 810%, Na2O 0.45%.

Since the manufacturing method was the same as in Example 1, only the differences will be described, except that the firing temperature was 1220°C.

The quality characteristics were good as shown in Table 8.

Table 8 The coefficient of thermal expansion was 5.6Xl0-6.

Although this invention has been described with reference to specific examples, the main raw materials are natural raw materials, and there are large variations in chemical components, and the description of the claims takes this variation into consideration.Examples 1 to 4 It is not limited to the value of chemical components.

[Effects of the Invention] As explained above, the present invention has the effect of providing a white soft porcelain sintered body with elegant translucency and a manufacturing method thereof industrially easily and inexpensively.

[Brief explanation of the drawing]

FIG. 1 is an X-ray chart showing the mineral composition of the sintered body of Example 1.

Claims (2)

[Claims] 1. SiO_255.00-48.00% in weight%, A
l_2O_325.00~20.00%CaO18.0
0~12.00%, P_2_O_59.00~5.00
%, K_2O4.00-2.00%, and the total amount of Na_2O and MgO mixed from the raw materials used as impurities is 2.
．． 00~0.10%, Fe_2O_31.00~0.2
A soft porcelain sintered body consisting of chemical components of 0% and TiO_20.70-0.10%, and whose main constituent mineral is anorthite. 2. A method for manufacturing a soft porcelain sintered body, comprising sintering a molded body comprising the chemical component according to claim 1 in an oxidizing atmosphere at a firing temperature of 1150 to 1250°C.