JPH0443867B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a method for producing a cristobalite porcelain base, which produces a porcelain product that has a wide range of uses as tableware porcelain and electrical porcelain, and has high mechanical strength. (Prior art) Porcelain has excellent whiteness and mechanical strength, so it is widely used in tableware, ornaments, and electrical products such as insulators. The main ingredients are Amakusa pottery stone and Izumiyama pottery stone, which have quartz and sericite as their main ingredients. There is a method in which the quartz component is transferred to cristobalite through a raw material processing step, followed by a molding step, drying, and firing step, thereby developing the mechanical strength unique to porcelain. In particular, when high-quality Amakusa pottery stone is used as a raw material for pottery stone, the quartz contained therein is fine, so cristobalite crystals are formed in the porcelain after firing, providing high-quality porcelain with excellent mechanical strength. can do. However, in recent years, high-quality Amakusa pottery stone has become depleted, and as an alternative raw material, silica sand (average particle size of about 700 μm), which is a quartz component, is used and wet-pulverized along with feldspar, pottery stone, clay, etc. It is proposed to produce porcelain blanks. (Problem to be solved by the invention) However, raw silica sand with an average particle size of about 700 μm,
If relatively hard non-plastic raw materials such as feldspar and silica stone are simultaneously wet-pulverized with low-hardness plastic raw materials such as pottery stone and clay, the hard silica sand and feldspar, which are non-plastic raw materials, are difficult to crush, so the entire blended raw material is The pulverization efficiency deteriorates, making it impossible to achieve homogeneous pulverization, and coarse quartz particles (particle size of about 30 μm or more) remain in the pulverized raw material matrix. During the firing process, fine quartz melts and cristobalite crystallizes from the melt, but if the quartz is coarse-grained, the coarse-grained quartz remains in the porcelain even after sintering, and the porcelain itself becomes heterogeneous. This reduces the mechanical strength of the porcelain. Furthermore, since the quartz remaining in the base material also reduces the transparency of the porcelain, this also has the disadvantage of causing a deterioration in the quality of the porcelain product. (Means for Solving the Problems) Therefore, in view of the above points, the present invention eliminates the non-uniformity of pulverization caused by simultaneously pulverizing various raw materials with different hardnesses and properties, and eliminates the non-uniformity of pulverization that occurs when coarse quartz remains. This is a method for producing cristobalite porcelain with the aim of suppressing the silica sand, promoting the transition of quartz to cristobalite, and obtaining cristobalite porcelain with strong mechanical strength. It is characterized by adding a certain amount of clay and wet-pulverizing it to a predetermined particle size, and then adding and mixing the remaining clay to both crushed products to adjust the composition and particle size. In particular, the present invention solves the non-uniformity of pulverization that conventionally occurred by simultaneously pulverizing various raw materials with different properties, by classifying them according to their properties and hardness, and separating non-plastic raw materials and plastic raw materials into wet pulverization to a predetermined particle size. It is something to do. Furthermore, since silica sand, silica stone, feldspar, etc., which are non-plastic raw materials, are precipitated and separated after being crushed, in order to prevent the sedimentation of the pulverized material, clay is added in an amount that prevents the pulverized material from settling, usually 4 to 8 ml of clay. It is important to add 5% to 6% by weight, preferably 5 to 6% by weight. It is also important to calculate the composition and particle size of the base material in advance so that the mixture of the non-plastic raw materials and the plastic raw materials and the particle size match the predetermined composition and particle size after mixing the residual clay. Note that when fine alumina powder is used as an alumina source material, it may be added at the time of pulverizing the plastic raw material to disintegrate agglomerates. (Example) First, silica sand and non-plastic raw materials such as feldspar are mixed in a predetermined ratio, and approximately 5% clay is added to prevent precipitation, and the mixture is milled in a ball mill to obtain particles with a particle size of 10 μm or more. The coarse grain part of
Wet grind until ~6 μm. On the other hand, a predetermined amount of plastic raw materials such as pottery stone and fine alumina powder, etc., are added if desired, and a coarse grain portion with a grain size of 10 μm or more as described in the base grain size in Table 1 is produced using a ball mill.
Wet grind until the powder has a content of 17 to 42 wt% and an average particle size of 3 to 7 μm. Next, the separately wet-milled non-plastic raw material and plastic raw material are mixed to give the base particle size of 27wt% as shown in Table 1, and the remaining clay is added to make the base composition as shown in Table 1. The cristobalite porcelain bases No. 1 to No. 6 of the present invention were manufactured by preparing the base composition and the base particle size as follows. On the other hand, as the first comparative example, porcelain base A
was mixed with pottery stone, silica stone, feldspar, etc. in a predetermined ratio without adding silica sand, and wet-pulverized at the same time so that the composition and particle size were almost the same as those of the present invention, and then, as in the previous example, A porcelain base shown in Comparative Example A in Table 1 was produced by mixing with clay in a tank.
In addition, as a second comparative example, a porcelain base shown in Comparative Example B in Table 1 was produced by wet-pulverizing porcelain base B with silica sand, pottery stone, feldspar, clay, etc. at the same time. (Functions and Effects) As described above, the porcelain base produced by the method of the present invention and the porcelain base produced as a comparative example were molded by a conventional method, and fired after drying at a temperature increase rate of 10 to 20.
℃/hr, sintering temperature 1200-1220℃, holding time at sintering temperature 0.5-2hr, cooling rate 10-20℃/hr,
The properties of the obtained porcelain (thermal expansion coefficient, amount of precipitated crystals, bending strength, residual quartz grain size) are shown in Table 1 together with the manufacturing conditions of the base material. In addition, in Table 1, the amount of precipitated crystals of porcelain is measured by X-ray diffraction quantitative method, and the bending strength is 12φ×
A 100 mm cylindrical specimen was measured using a three-point support bending test method, and the residual quartz grain size in the porcelain was measured using a scanning electron microscope.

【table】

[Table] As shown in this table, the porcelain obtained by sintering the base material manufactured by the manufacturing method of the present invention, in which non-plastic raw materials and plastic raw materials are separately wet-pulverized to the desired particle size, is made from non-plastic raw materials. The flexural strength is greater than that of the porcelain obtained by sintering the base material B produced by wet-pulverizing and the plastic raw material at the same time (Comparative Example B).
Moreover, the quartz grains remaining in the porcelain are small in size, so it has excellent strength. In addition, the strength and residual quartz grain size are not inferior to the porcelain obtained from base A manufactured without using silica sand (comparative example A), and the SiO ₂ component of high-quality pottery stone, which is tending to be depleted, is The quality of porcelain can be maintained even if some of it is replaced with silica sand. However, even in the present invention, when the pulverized particle size of both plastic and non-plastic raw materials becomes coarse, the residual quartz particle size increases and the mechanical strength decreases, so the pulverized particle size of the non-plastic raw material is
10μm or more is 30% or less, and the crushed particle size of plastic raw materials is
It is preferable that 37% or more is 10 μm or more. As is clear from the above description, the present invention can suppress the residual coarse-grained quartz in porcelain, promote the transition of quartz to cristobalite, and provide high-quality porcelain with excellent strength. As a manufacturing method for porcelain bases, it eliminates the problems of the conventional method and greatly contributes to the development of industry.

Claims (1)

[Scope of Claims] 1. Clay is added in an amount that prevents precipitation and separation to non-plastic raw materials such as silica sand and feldspar, and the mixture is wet-pulverized to a predetermined particle size.
Separately, a method for producing a cristobalite porcelain base is characterized in that a plastic raw material such as pottery stone is wet-pulverized to a predetermined particle size, and then residual clay is added to and mixed with both crushed products. 2. The method for producing a cristobalite porcelain base according to claim 1, wherein the average particle size of the plastic raw material after wet milling is equal to or smaller than the average particle size of the base.