JPH1143381A - Porous lightweight pottery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lighten the weight, lower the water absorption and increase the strength of a porous and lightweight pottery by plastically molding a composition containing fly ash balloons as an aggregate, an organic and inorganic plasticizer and sintering additives and firing the molded products at a specific temperature. SOLUTION: Fly ash balloons with a 50% particles size of 20-200 μm, preferably 20-100 μm, a cell thickness of 1-20 μm, preferably 2-10 μm and a refractoriness of >= SK6a in an amount equal to or more than 10 pts.wt., <=50 pts.wt. of kaolinite clay and/or <=50 pts.wt. of montmorillonite, and 10-90 pts.wt. of organic or inorganic plasticizer comprising 0-10 pts.wt. of a plasticizer and 25-35 pts.wt. of a sintering agent as feldspar, glass fritter and the like are formulated to prepare a composition. The resultant composition is molded by plasticization by means of a pedal type bellow, a handy potter wheel, a jigger or a wet-type press, and the molded products are fired at 1,000-1,350 deg.C to prepare a porous light-weight pottery with an apparent specific gravity of 0.6-2.0, moisture absorption of <=5.0%, flexural strength of >=100 kgf/cm<2> .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous, lightweight porcelain, and more particularly, to a lightweight, low-water-absorbing, high-strength porcelain obtained by adding a high-fire-resistant fly ash balloon.

[0002]

Heretofore, it has been common knowledge that ceramics are heavy and easily broken, so that producers, dealers and consumers have been burdensome. At present, low back pain and hernia frequently occur among employees, especially in large ceramics production areas, which is a factor that makes it difficult for young workers to succeed. In the age of aging, it is necessary to reduce the burden not only on manufacturers but also distribution and transportation companies. Consumers are often shunned by everyday items such as large dishes that are difficult to carry, due to their weight.
Lightweight pottery is expected to be used for products that have been shunned because they want to have the sensitivity and room of pottery, but have been shunned because of their heavy weight, pottery for disabled people, tableware, and so on.

[0003] Accordingly, although many proposals have been made on the weight reduction of ceramics, there have been few proposals that can withstand practical use. For example, a method is known in which fine particles of an organic substance are added, and pores are formed by burning, vaporizing, and disappearing at the time of firing, thereby reducing the weight of the pottery.
As the fine particles of the organic substance to be added, sawdust, coffee beans pomace, pulverized coal, carbon powder, hollow resin powder, and the like have been proposed. However, in this proposal, the odor during molding, the residual carbide due to incomplete combustion,
There are problems such as deformation of the base material due to expansion during firing, generation of black smoke, and the like, so that it has not been put to practical use.

Further, glass balloons, shirasu balloons,
In the proposal to add an inorganic hollow body such as pearlite foam,
Because of the low fire resistance of these additives, they melt or eutectic at a general ceramic firing temperature of 1100 to 1350 ° C., and the firing shrinkage becomes large, so that it is difficult to reduce the weight sufficiently and the dimensional accuracy is poor. There was a problem.

[0005] These conventional proposals have a further common problem. In other words, when a large amount of additive substance is added, the raw material becomes bulky, and the plasticity is remarkably reduced, which makes molding difficult. In many cases, plastic molding is relatively easy, since communication holes are easily formed and the strength is low. In addition, plastic molding in which closed pores are formed is considerably difficult, and in order to perform plastic molding, the amount of the added substance must be limited, and sufficient weight reduction cannot be achieved.

In order to solve the above-mentioned conventional problems, the present inventor can carry out plastic molding even if a relatively large amount of additives are mixed, and has good dimensional accuracy, high strength and low water absorption. As a result of intensive studies on means for obtaining pottery, the present invention has been reached.

[0007]

The present invention takes the following means to solve the above-mentioned problems. That is, the gist of the porous lightweight pottery according to the present invention is as follows.
More than 10 parts by weight of a fly ash balloon having a fire resistance of at least SK6a is used as an aggregate, and 10 to 90 parts by weight of an organic or inorganic plasticizer and a sintering agent are added. That is, the firing is performed at a temperature lower than 1350 ° C.

Further, in such a porous lightweight ceramic,
The fly ash balloon used has a 50% particle size of 20%.
μm to 200 μm, and the cell thickness of the fly ash balloon is 1 μm to 20 μm.

Further, in such a porous lightweight ceramic,
Apparent specific gravity is 0.6 or more and less than 2.0, and water absorption is 5.0%
Less than 100 kgf / cm ² .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the porous lightweight pottery according to the present invention will be described in detail.

The fly ash balloon used in the present invention may have a fire resistance of at least SK6a, and its shape is not particularly limited, but is preferably spherical. The fly ash balloon as referred to herein refers to fine particles of combustion ash that have been purified and separated by flotation from fine particles collected by a dust collector, and are hollow fine particles having a specific gravity of 1 or less. It is mainly generated from thermal power plants using pulverized coal, but its shape, size, composition, fire resistance and other properties vary depending on the place of production and composition of coal, the combustion method, the classification method, and the like.

Generally, in order to increase the strength of the ceramic, the firing temperature must be increased. If the added fly ash balloon has low fire resistance, the fly ash balloon is deformed by melting during sintering or eutectic melting with the matrix, so that the hollow state is broken and no pores remain. Therefore,
Fire resistance that does not deform at the firing temperature is required.
In order to withstand an appropriate firing temperature of not less than 00 ° C. and not more than 1350 ° C., the fire resistance must be SK6a or more.

The particle size of the fly ash balloon to be added is an important factor influencing the plasticity of the clay, and if it is too large, the clay loses the stickiness and the molding becomes difficult. descend. Conversely, if it is too small, the kneading of the kneaded clay is lost and plastic molding becomes difficult,
Since sintering proceeds excessively, firing shrinkage becomes large, and it is difficult to reduce the weight. Also, the dimensional stability decreases. The particle size of the fly ash balloon used in the present invention is from 20 μm to 200 μm.
μm, and more preferably 20 μm.
μm to 100 μm.

[0014] The cell thickness of the fly ash balloon to be added is also an important factor affecting the physical properties of the fired pottery. When the cell thickness is too large, cristopalite due to phase transition remains, which may cause point separation or cooling after firing. Further, a cell having a too small thickness is not preferable because it is easily broken in a series of manufacturing steps and the number of pores in the fired product is reduced. Therefore, the cell thickness is preferably from 1 μm to 20 μm, and more preferably from 2 μm to 10 μm.

The amount of the fly ash balloon used in the present invention is more than 10% by weight. The higher the ratio, the lighter the pottery, but in order to actually make a product, a plasticizer for molding and a sintering agent for sintering are required, and the amount of fly ash balloon added There is a limit naturally. If the amount is small, plastic molding is easy, but a sufficiently light product cannot be obtained. In the present invention, even if the amount of addition exceeds 10% by weight, which was impossible with the conventional technology, plastic molding can be performed by appropriately selecting a plasticizer and a sintering agent.
This made it possible to manufacture lightweight ceramics having an apparent specific gravity of 2.0 or less.

The plastic molding in the present invention is a molding method which is generally widely used and utilizes the plasticity of clay, and is not particularly limited. Various techniques are used, such as tatara, hand potter's wheel, machine potter's wheel, wet press. The definition of plasticity is such that the material is deformed by applying a force of a certain magnitude or more, and the deformed state is maintained even when the force is removed. However, at the pottery site,
It is evaluated based on feelings such as waist and stickiness. . Also in plastic molding, the required properties and the amount required vary depending on the method and the product to be made. Porcelain clay is roughly divided into pottery stands and clay feldspar stands. In the case of pottery stones, the sericite component in the pottery stone acts as a plasticizer and sintering agent. Becomes a sintering agent.

Next, the plasticizer used in the present invention will be described. Generally, a plasticizer is indispensable for plastic molding, and about 30 to 40% by weight is required in a usual clay-made base material. In the present invention, in addition to ordinary kaolinite clay as a plasticizer, a highly viscous montmorillonite clay or an artificial plasticizer is used to enable plastic molding with a relatively small amount of use. Since fly ash balloons have a large volume and a very large specific surface area, plastic kaolinitic clay alone cannot be molded unless it is mostly formulated for plastic molding, and the proportion of fly ash balloons must be reduced I can't get it. In the present invention, in addition to the kaolinitic clay, the use of a montmorillonite clay having a higher tenacity and a lower fire resistance than the kaolinitic clay enables plastic molding with a small amount of a plastic component and adjustment of sinterability. Became possible. Further, as an additive for supplementing plasticity, an organic or inorganic dispersant or a plasticizer may be added. The preferred ratio of each additive is
50 parts by weight or less of kaolinitic clay, 50 parts by weight or less of montmorillonite clay, the amount of clay when both are used together is 10 to 50 parts by weight, and the plasticizer is 0 to 1 part by weight.
0 parts by weight.

The sintering agent is generally feldspar, and is contained in the general clay in an amount of 25 to 35% by weight. However, in order to sufficiently sinter a fly ash balloon having a large surface area and a plasticizer, feldspar alone is not possible, and it is not possible to obtain ceramics having low water absorption and high strength. In the present invention, a fine powder of feldspar or glass frit having good melting property is used, and further, an alkali or alkaline earth mineral or metal oxide having a eutectic property with a fly ash balloon is prepared, thereby sintering with a small amount of addition. I found a range to do. Examples of alkaline earth minerals include talc, limestone, magnesite and the like. These sintering agents are finely pulverized and added as particles having an appropriate particle size, whereby an effect of improving plastic moldability and enhancing sinterability can be obtained. The preferred amount of sintering agent is 5 for feldspar and glass frit.
0 parts by weight or less, and 10 parts by weight or less for alkali or alkaline earth minerals and metal oxides.

The porous lightweight pottery obtained by the above-described manufacturing method is a pottery having contradictory characteristics of lightness and strength. In particular, the apparent specific gravity is 0.6 or more and less than 2.0, the water absorption is less than 5.0%, and the bending strength is 100 kgf /
Pottery satisfying physical properties of not less than ² cm ² has not been known so far, and new applications can be developed in various fields. In the fields of light and easy-to-use large ceramics, heat insulating materials, lightweight tableware, gardening goods, building materials such as tiles and wall materials, products that have been difficult with the conventional technology can be put into practical use.

In particular, the following means can be used to reduce the apparent specific gravity. That is, a method in which organic fine particles are blended in the kneaded material, burned, vaporized, and disappeared during firing, and pores are formed after the disappearance. Pre-coating a plasticizer or a sintering agent on the fine particles in advance or using hollow fine particles is a more preferable method, and an ultralight and relatively high-strength ceramic can be obtained.

The thermal expansion coefficient of the fired body according to the present invention is smaller than that of a general base. This is because, in the conventional substrate, the silica as the aggregate is transformed into beta quartz at 573 ° C. and abnormally expands, whereas in the substrate of the present invention, the fly ash balloon as the aggregate crystallizes mullite, so that the thermal expansion coefficient is increased. Is smaller. Therefore, the glaze applied to the fired body of the present invention needs to be slightly smaller than the usual glaze.

Various physical properties described in the present invention were measured by the following methods. That is, the fire resistance of the fly ash balloon: JIS M851
2 Particle size of fly ash balloon: laser diffraction method Cell thickness of fly ash balloon: Calculated from apparent specific gravity and particle size with true specific gravity being 2.5.

Apparent specific gravity of fired body: calculated from volume and weight measured by a conventional method Water absorption of fired body: JIS A5209 Flexural strength of fired body: Measured according to JIS A5209.

The present invention is based on the knowledge of those skilled in the art with regard to the type and particle size of the fly ash balloon, the type and blending ratio of the plasticizer and sintering agent, the plastic molding method, the firing conditions, etc., without departing from the scope of the invention. The present invention can be implemented in various modified, modified, and modified embodiments.

Embodiments of the present invention will be described in detail below.

Examples 1 to 4 A porous lightweight ceramic according to the present invention was manufactured under the conditions shown in FIG. The fly ash balloon used was a commercial product, the product with a fire resistance of SK27 was Microcells manufactured by Chichibu Onoda Co., Ltd., and the product with a fire resistance of SK20 was Senolite manufactured by Nippon Philite Co., Ltd. The manufacturing procedure is as follows. First, fly ash balloons that had been calcined and burst at a temperature that did not self-sinter were ruptured. Next, this was mixed with ordinary clay or plasticizer powder, and a predetermined amount of sintering agent powder and water were added and kneaded to form a clay. The kneaded material was embossed into a rod shape using a gypsum mold and oxidized and fired at a predetermined temperature using an electric furnace.
Various physical properties were measured by the methods described above.

Examples 1 to 4 were all manufactured to satisfy the conditions of claim 1, and had good plastic moldability. Further, the effect of weight reduction was remarkable, and a fired body having excellent physical properties could be obtained. Among them, Examples 2 to 4
Is manufactured satisfying the condition of claim 2,
In particular, it was confirmed that a fired body having high strength and low water absorption could be manufactured. The physical properties of the fired bodies manufactured according to Examples 2 to 4 satisfy the condition of claim 3 and enable development of new applications.

Comparative Example 1 As shown in FIG. 1, a comparative experiment was performed using a shirasu balloon having a fire resistance of SK3a. Since the fire resistance was low, the temperature was lowered to 1100 ° C., and firing was performed. However, it was determined that pores were not well formed due to deformation of the shirasu balloon, and as a result, the apparent specific gravity and water absorption could not be sufficiently reduced. .

[0029]

According to the porous lightweight ceramics of the present invention, delicately shaped ceramics can be manufactured because plastic molding is possible.
Industrially low-cost production becomes possible.

Further, by utilizing the excellent lightweight characteristics, it is possible to provide light-weight ceramics such as building materials such as tiles and tiles, gardening supplies such as flowerpots, tableware for the handicapped, large-sized ceramics and the like.

Further, since it contains a large number of independent pores, it can be used for various heat insulating materials and furnace materials by utilizing its excellent heat insulating property, heat resistance and light weight, and it can be used with low water permeability. If the material floats on water, it can provide a new lightweight material that is suitable for various types of floats and replaces wood and foamed plastic.

[Brief description of the drawings]

FIG. 1 is a table illustrating an overview of Examples 1 to 4 and Comparative Example 1.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masami Yokoigawa 498, Nagano, Shigaraki-cho, Koka-gun, Shiga Prefecture Inside Shigaraki Ceramics Technical Testing Center, Shiga Prefectural Institute of Technology (72) Inventor Yuji 498 Nagano, Shigaraki-cho, Koga-gun, Shiga Shiga Prefectural Industrial Technology Center Shigaraki Ceramic Technology Laboratory

Claims (3)

[Claims] 1. A refractory SK6 in an amount exceeding 10 parts by weight.
a or more, and an organic or inorganic plasticizer and a sintering agent are added in an amount of 10 to 90 parts by weight, and after plastic molding, 1100 ° C. to 1350
Porous lightweight pottery characterized by being fired at a temperature of less than ℃. 2. The porous lightweight material according to claim 1, wherein the fly ash balloon has a 50% particle size of 20 μm to 200 μm, and the fly ash balloon has a cell thickness of 1 μm to 20 μm. Pottery. 3. An apparent specific gravity of 0.6 to less than 2.0, a water absorption of less than 5.0%, and a bending strength of 100 kgf / cm ^2.
The porous lightweight pottery according to claim 1 or 2, characterized in that: