JP2015086350A - Composition for molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for molding capable of providing efficient strength and durability to a product while low temperature firing.SOLUTION: The composition for molding contains an aggregate, a clay, oligo lactic acid and inevitable mixture and is used for manufacturing a prescribed article.

Description

The present invention relates to a composition that can be fired at a low temperature and is a material for various molded articles such as ceramics and building materials in consideration of environmental load.

  Various items are used in our living space. For example, daily necessities such as tableware, building materials used for walls and floors of buildings, and crafts adapted to hobbies and tastes are used in various living spaces. These daily necessities, building materials, crafts, and the like are often manufactured using natural raw materials mined from the natural world. For example, pottery stones mined from nature are often used to produce daily necessities and crafts. In addition, building materials are sometimes manufactured using natural raw materials mined from the natural world.

  Here, a raw material that is mined and processed from the natural world, such as porcelain and mixed soil, and used as a raw material for manufacturing daily necessities, building materials, crafts, and the like is referred to as a molding composition. That is, articles having a certain shape such as daily necessities, building materials, and crafts are manufactured by being molded from a plastic material and solidified. For this reason, the raw material used as the raw material which manufactures articles | goods, such as these daily necessities, building materials, and crafts, will be called a composition for shaping | molding. In addition, plasticity means a property in which deformation occurs continuously when a force is applied, and a state immediately before the force can be maintained when the force is removed.

  As described above, molding compositions such as porcelain clay and blended soil are generally mined and processed from the natural world. For example, in areas famous for pottery production in various parts of Japan, natural materials that are most suitable for producing porcelain have been produced at present or in the past. For example, Amakusa pottery stone in Kumamoto Prefecture has been mined from the Edo period to the present, and is consumed mainly in the Kyushu region as a ceramic raw material. Thus, porcelain clay is manufactured from natural raw materials, and daily necessities and crafts are manufactured using this porcelain.

  On the other hand, in recent years, the quality of the above-mentioned porcelain clay materials has decreased, and it has become difficult to mine high-quality porcelain clay materials in a sufficient amount. For example, the production of ceramics with the name of the area, called “Daiden Yaki”, originally used porcelain materials produced in or near the area, but these porcelain materials were mined for many years. Therefore, there is a problem that the amount of mining cannot be secured sufficiently.

  In some cases, there is a growing concern about mining a large amount of natural earthen clay material as the awareness of environmental issues increases in recent years. This is because in the mining of porcelain material, it is actually practiced to cut mountains or reduce forests. This is because reducing mountains and forests is not preferable in global warming using carbon dioxide as an index.

  In addition to daily necessities and crafts, most of the molding compositions used to produce building materials are mined from nature. Rocks and minerals mined from nature are processed according to their purpose, and building materials are manufactured through processes such as molding and processing.

  As described above, a composition for producing various articles such as daily necessities, crafts, and building materials often uses natural raw materials mined from the natural world. Similar to the above-mentioned porcelain clay materials, there is a problem that the minable amount of these natural materials mined in nature is reduced. This is because there is a problem of the environmental load caused by mining along with the problem that the minable reserves are decreasing.

  On the other hand, daily commodities and crafts such as those described above are full of products made of synthetic resin rather than ceramic. Ceramic dishes such as dishes, teacups, and cups, which are familiar to daily life, have been replaced by synthetic resins that have a short manufacturing process and low manufacturing costs. That is, a synthetic resin eating and drinking apparatus can be manufactured at a much lower cost than a ceramic product by a stable supply of raw materials and a highly productive manufacturing process using an injection molding machine.

  As for the raw material of synthetic resin, since the raw material is basically petroleum and shares the supply source with many other consumer goods, the cost can be reduced.

  In this way, the raw material cost of synthetic resin and the processing cost for molding are kept lower than those of ceramic materials, which is a major reason why synthetic resin products are replaced with ceramic products.

  However, daily necessities and crafts using synthetic resin artificial materials in this way cause new environmental problems due to their disposal. As described above, because of ease of manufacturing and low cost, the market is overflowing with plastic products that are one of artificial material products. The raw material for this plastic is fossil fuel, and the increase in plastic products has led to an increase in the amount of fossil fuel used. In this respect, the environmental load is increased.

  In addition, daily necessities and crafts are often disposed of for a short time in a disposable manner, and there is a problem that many plastic products are discarded every year. The plastic products to be discarded are not limited to daily necessities and crafts, but include various items such as office supplies, electrical appliances, and parts of transportation equipment.

  As described above, in the modern society, many plastic products are overflowing, including plastic products that have been replaced with products that have been manufactured with ceramics. Many of these plastic products are disposed of in large quantities after a short period of use. Most of these waste plastics are incinerated or landfilled.

  When incinerated, there is a problem of generating harmful chemical gases. There is also a problem that a large amount of carbon dioxide, which is a cause of global warming, is discharged along with incineration. In the case of landfill disposal, there is a shortage of landfill sites, and problems such as soil contamination and water pollution after landfilling are caused.

  Thus, there are various problems around us that articles made of artificial materials such as plastics have become mainstream. In summary, (1) mass consumption of fossil fuel, (2) mass disposal of plastic products etc. manufactured with fossil fuel and disposal of discarded plastic products, (3) increase in disposable orientation due to low cost, etc. There's a problem.

  In this way, it is possible to return daily commodities and crafts already mass-produced with plastics to compositions using raw materials mined from the natural world as in the past, to solve the problems (1) to (3) above. The first step.

  However, when manufacturing daily necessities, crafts, building materials, etc., with a molding composition such as porcelain using raw materials mined from the natural world, as already mentioned, the minable amount in the natural world is the reserve amount. Facing problems that are decreasing due to environmental problems. As a result, there is a problem that the cost of the molding composition as a raw material increases. In addition, in order to produce daily necessities and crafts using a molding composition made of natural materials such as porcelain materials, various manufacturing processes such as molding, drying, firing / solidification, processing / finishing are required. For this reason, there is a problem that not only the cost of the molding composition itself, which is a raw material, but also the cost of manufacturing the article for manufacturing the article is increased.

  In this way, in order to produce commodities such as daily necessities, crafts, and building materials manufactured from artificial materials such as plastics, using the molding composition obtained from natural raw materials mined from the natural world, securing the mining amount, mining Industrial problems such as environmental load, material cost, and manufacturing cost are obstructive factors.

  In addition, when an article is manufactured using an artificial material such as plastic, it is only necessary to mold a plate material that has already been solidified, so that heat treatment is not required in the article manufacturing process.

  On the other hand, in the case where soil or rocks mined from nature are used as a raw material for porcelain, it is necessary to mold the porcelain material before firing and densify and solidify it. Since this densification / solidification requires a large amount of heat energy, there is a problem of causing an environmental load due to consumption of the corresponding fossil fuel. Even if it is an artificial material, heat is required in processes such as processing, but the temperature is not high.

  On the other hand, the firing temperature for solidifying the composition based on natural materials is very high. For example, in order to manufacture daily products for unglazed baking using ceramic clay obtained from natural raw materials, a temperature of about 900 ° C. is required for the baking. Alternatively, a temperature of 1200 ° C. or higher is required to produce daily ceramic items using porcelain obtained from natural raw materials.

  In order to realize these extremely high firing temperatures, it is a matter of course that environmental burdens such as energy consumption and carbon dioxide emission accompanying combustion are brought about. Moreover, since not only the firing temperature is high but also a long firing time is required, problems of energy consumption and carbon dioxide emission arise from both the firing temperature and the firing time. Of course, the management cost of the manufacturing process due to the baking temperature and the size of the baking time also increases, and as a result, the manufacturing cost increases.

  Thus, when manufacturing daily necessities and crafts using a molding composition obtained from a natural raw material mined from the natural world, there is a technical problem in the manufacturing process.

  As described above, in order to solve the problems of modern society such as the disposal of plastic products that are artificial materials and the consumption of fossil fuels, the daily use of artificial materials and crafts are made from natural raw materials mined from the natural world. There is a need to return to daily goods and crafts.

  However, this need to return has the following industrial and technical challenges.

(Problem 1) The minable amount of natural raw materials mined from the natural world is decreasing.
(Problem 2) When mining natural raw materials from the natural world, an environmental problem of destroying mountains and forests is caused.
(Problem 3) When manufacturing an article using a natural raw material as a composition (such as porcelain clay), there is a problem of requiring a long baking temperature and baking time for solidification.
(Problem 4) Based on problem 3, there is an environmental load problem of carbon dioxide emission due to combustion.

  There is a demand for a new molding composition for producing an article that solves these problems 1 to 4 while using natural raw materials mined from the natural world. In such a situation, a composition has been proposed (for example, see Patent Document 1).

JP 2008-101096 A

  Patent Document 1 shows that when the total amount of the polylactic acid-based composition containing the polylactic acid-based polymer, the baked scallop shells and kaolin is 100% by mass, the polylactic acid-based polymer content is 30 to 85% by mass, Disclosed is a polylactic acid-based resin composition having a baked scallop pulverized content of 5 to 40% by mass and a kaolin content of 5 to 50% by mass.

  The composition disclosed in Patent Document 1 is used as a material for molding and manufacturing daily goods such as so-called tableware and crafts such as dolls. The composition disclosed in Patent Document 1 uses a polylactic acid polymer as a composition while using a material that can be discarded as a scallop pulverized product, not natural porcelain itself, but from the natural world. The amount of mined porcelain is reduced.

  Further, the composition disclosed in Patent Document 1 can be fired at a firing temperature of 100 ° C. to 300 ° C., which is very low compared to porcelain clay mined from nature (hereinafter referred to as “natural porcelain clay”). . In this way, Patent Document 1 attempts to solve the above-described problems 1 and 2.

  The composition disclosed in Patent Document 1 uses a polylactic acid polymer as a main raw material. On the premise of this polylactic acid polymer, we are trying to realize a substitute for porcelain clay using baked scallop shells as aggregates.

  However, the polylactic acid polymer has a large molecular weight, and its ability to bind the baked scallop shell pulverized product with other materials of kaolin is weak. In addition, since the polylactic acid polymer is not water-soluble, it cannot exhibit the properties as a binder, and in this respect as well, the ability to bind other substances is weak. Thus, even if the composition of patent document 1 can make a calcination temperature low, it has the problem that the intensity | strength and durability of the manufactured finished product are weak.

  Moreover, although the composition disclosed by patent document 1 uses the baked scallop shell ground material as an aggregate, an unnecessary cost may arise in manufacturing and obtaining a fired scallop shell ground material. Scallop shells are easy to obtain in places where scallop production areas and scallop processing plants are located. However, in these places, scallop shells are not necessarily fired, and waste scallop shells must be fired. This firing naturally causes an environmental load such as emission of carbon dioxide.

  In addition, the origin of scallop shells and the place where the polylactic acid-based resin composition of Patent Document 1 is used are often far from each other, and environmental burdens such as transportation costs of scallop shells and carbon dioxide emissions due to transportation are generated. Is also a problem. As a result, the production costs of various products produced using the composition disclosed in Patent Document 1 are increased.

  Thus, the prior art composition disclosed in Patent Document 1 has the following problems.

  (Problem 1) The strength and durability of the product are lowered because the bonding force between the raw material particles constituting the molding composition is weak.

  (Problem 2) The production cost and transportation cost of each of the raw material particles constituting the molding composition are increased, and the production costs of various products finally produced are also increased.

  (Problem 3) The environmental load in the production process and transportation process of the raw material particles constituting the molding composition is large.

  The present invention provides a molding composition capable of simultaneously solving the above-mentioned problems 1 to 4 while solving these problems 1 to 3 and imparting sufficient strength and durability to a product while being low-temperature firing. The purpose is to do.

  In view of the said subject, the molding composition of this invention contains an aggregate, clay, oligolactic acid, and an unavoidable mixture, and is used for manufacture of a predetermined | prescribed article.

  Since the molding composition of the present invention uses oligolactic acid obtained from waste plastics collected at various places as one of the raw materials, the production site of oligolactic acid and the place where various products using porcelain are produced The separation distance can be shortened. Of course, since the oligolactic acid can be easily obtained, the manufacturing cost and the transportation cost of the molding composition can be reduced. In addition, it is possible to reduce the environmental burden in the manufacturing and transportation process of the molding composition.

  In addition, since the molding composition of the present invention contains a certain amount of oligolactic acid in aggregates and clays mined from the natural world, the amount of natural raw material required for the final manufactured article is relatively Can be reduced. For this reason, the subject of the reduction of the minable amount of the natural raw material which needs to be mined in nature can be solved.

  Furthermore, since the molding composition of the present invention can be fired at a low firing temperature, a product can be produced even without a dedicated kiln. In addition, oligolactic acid works well as a binder between particles, such as aggregate particles and clay particles, which are natural raw materials in molding compositions, due to its low degree of polymerization and molecular weight, thereby improving the strength and durability of the product. Can be improved. In addition, since the firing temperature is significantly lower than the firing temperature, the thermal energy required for firing can be significantly reduced, and the manufacturing cost can be reduced.

  For this reason, the spread is promoted, and the replacement of the plastic product or the like with the product using the molding composition of the present invention containing the natural raw material proceeds. As a result, it is possible to suppress an increase in waste of artificial materials that are difficult to dispose of and to solve environmental problems. In particular, since oligolactic acid is obtained from the decomposition and pulverization of waste plastics that have already been discarded, it is possible to produce articles that are not difficult to dispose by recycling the waste, which is very suitable for the recycling industry.

  The molding composition according to the first aspect of the present invention contains aggregate, clay, oligolactic acid and an unavoidable mixture, and is used for producing a predetermined article.

  With this configuration, in the molding composition, it is possible to reduce the ratio of natural raw materials mined from the natural world and to provide materials for manufacturing various articles.

In the molding composition according to the second aspect of the present invention, in addition to the first aspect, oligolactic acid has a polymerization degree of 2 or more and less than 500.
In the molding composition according to the third aspect of the present invention, in addition to the first aspect, oligolactic acid has a molecular weight of 180 or more and less than 50,000.

  With these configurations, oligolactic acid can be uniformly and widely dispersed inside the molding composition. As a result, oligolactic acid can exhibit a wide range of functions as a binder.

  In the molding composition according to the fourth invention of the present invention, in addition to any of the first to third inventions, oligolactic acid is obtained by pulverizing waste plastic in a predetermined step.

  With this configuration, oligolactic acid can be obtained by recycling. As a result, the produced molding composition can reduce the environmental load in addition to reducing the proportion of natural raw materials and lowering the firing temperature required for solidification.

  In the molding composition according to the fifth aspect of the present invention, the predetermined step includes a decomposition treatment with superheated steam.

  With this configuration, oligolactic acid having a small degree of polymerization and a low molecular weight can be easily obtained.

  In the molding composition according to the sixth aspect of the present invention, in addition to any of the first to fifth aspects, the predetermined article is any one of ceramics, daily necessities, crafts, and building materials.

  With this configuration, the molding composition can be applied to various articles produced through a molding process and a baking process.

  In the molding composition according to the seventh aspect of the present invention, in addition to any of the first to sixth aspects, the aggregate is quartz or feldspar.

  With this configuration, the aggregate can make a skeleton of the molding composition.

  In the molding composition according to the eighth aspect of the present invention, in addition to the seventh aspect, quartz or feldspar is derived from natural ceramic stone.

  With this configuration, the aggregate can be easily obtained.

  In the molding composition according to the ninth aspect of the present invention, in addition to any of the first to eighth aspects, the clay is kaolin clay or muscovite containing a kaolin mineral as a main component.

  With this configuration, clay can be easily obtained. Moreover, the molding composition excellent in plasticity is obtained.

  In the molding composition according to the tenth aspect of the present invention, in addition to the ninth aspect, the kaolin clay is kaolin clay derived from Kibushi clay, New Zealand kaolin, or British SP kaolin.

  With this configuration, a molding composition having excellent moldability and high whiteness can be obtained.

  In the molding composition according to the eleventh invention of the present invention, in addition to any of the first to tenth inventions, the clay is kaolin clay or muscovite derived from Amakusa porcelain clay or Shichijo clay.

  With this configuration, clay that can be easily mined from the natural world can be used.

(Embodiment 1)

Embodiments will be described.
(Overview)
The molding composition in the embodiment is a material for producing various articles such as daily necessities, crafts, and building materials. Here, since the molding composition in the embodiment is a material used for molding, it may be subjected to the following steps in order to be used as a material for manufacturing various articles.

  For example, when the molding composition is finally used for daily necessities and crafts, the molding composition may go through a ceramic clay stage. This is because, when these daily necessities and crafts are manufactured in the category of so-called ceramics, the molding composition is used as porcelain. Alternatively, when the molding composition is finally used as a building material, the molding composition goes through the building material material stage. Thus, the molding composition goes through a stage as a necessary raw material in accordance with the finally manufactured article. In addition, the molding composition may be grasped as a raw material necessary for producing the article as it is, or a raw material necessary for producing the article by performing another process or addition to the molding composition. It may be grasped by becoming.

  The molding composition contains aggregate, clay, oligolactic acid and an inevitable mixture. This molding composition is used as a material for manufacturing various articles such as daily necessities, crafts, and building materials. As above-mentioned, it will become a raw material of the next step by adding another process and another additive as needed to this molding composition. This material becomes the direct material of the final manufactured article.

  Aggregate is the basic raw material of the molding composition. Aggregate literally forms the main skeleton as the main component in the molding composition. That is, during molding, the aggregate is deformed into a target shape integrally with clay, which is a plastic component described later, and once the molding operation is finished, it becomes a skeletal component for maintaining the shape. . In other words, the aggregate provides the shape of the molded article, and at the same time, the aggregate forms a filling structure with each other, thereby resisting the force of the article, such as its own weight and external force, which tends to deform the article. It is responsible for maintaining the shape of the article. When the aggregate is contained in the molding composition as described above, the molding composition produces a shape and a certain strength of the article when used as a material for various articles.

  Clay imparts a certain plasticity to the molding composition. Due to this property, for example, the molding composition can be kneaded, molded and processed by adding moisture. In such processing, it is necessary that the material itself is easily mixed and formed with moisture and then easy to form and process. That is, when the molding composition is molded and processed at a stage where it is not solidified, the molding composition needs to have a certain degree of plasticity.

  Clay can impart plasticity when the molding composition is molded as a raw material. For example, when the molding composition is used as porcelain clay, an operator molds the porcelain clay into a predetermined shape by a technique such as roll molding or extrusion molding. In this work process, when the molding composition does not have a certain plasticity, it is naturally difficult to knead or mold. Of course, if the cracking or breaking occurs in the molding process, the article cannot be manufactured. Clay is a process of forming a molding composition, and when an external force is applied to the molding composition, it causes slippage between the component particles according to the external force to help deformation, and when the molding process ends, It is a component that imparts the plasticity necessary to maintain the previous state.

  Clay also produces not only plasticity during molding, but also green strength of the molded article (including solidification by firing at low temperatures). Green strength is also referred to as green strength, and is the strength of a molded product after molding. Moreover, since ceramics have a greater strength (firing strength) when fired, they are used as a term for the firing strength.

  In the embodiment, even when daily commodities and crafts are manufactured by using the molding composition as porcelain clay, and when building materials are manufactured by making the corresponding clay as well, these manufactured articles are It is required to have a certain green strength. The molded article does not need to be deformable after solidification, but preferably has a green strength as a stress against a pressure applied from the outside, that is, a handling strength.

  Even if a force that attempts to deform the molded product by its own weight or external force is applied after solidification, if the solidification has sufficient green strength, the possibility of actual deformation or breakage decreases. . When the molding composition that is a material for manufacturing the article includes the fiscal year, the manufactured article is given strength against pressure and impact. In other words, the aggregate and year are obtained by crushing mineral resources mined from the natural world. That is, aggregate and clay are natural materials.

  However, as explained in the prior art, high-quality natural raw materials mined in nature are decreasing. In addition, natural raw materials are terrestrial resources, and if large-scale mining is repeated based on industrial value, the original ground structure will be destroyed, leading to ground erosion and ground depression. . In recent years, mining of mineral resources has attracted social attention as an act of environmental destruction. As described above, the mineral as a natural raw material is different from the fossil fuel, but may have an environmental problem.

  Oligolactic acid can substitute for the volume of aggregates and clay, which are mineral raw materials, in constituting the molding composition. Moreover, since the density of oligolactic acid is about half that of aggregate and clay, when mixed with the molding composition, there is an effect of increasing the volume of the molding composition. That is, the proportion of the mineral raw material in the molding composition is relatively lowered.

  Thus, oligolactic acid can reduce the proportion of the mineral raw material in the total amount of the molding composition.

  Here, the oligolactic acid in the embodiment is produced by decomposing polylactic acid. Polylactic acid is obtained by polymerizing lactic acid, and its properties are similar to polyethylene terephthalate known as a general-purpose plastic. On the other hand, polylactic acid is a representative example of a biodegradable plastic because it is easily degraded in nature by the action of microorganisms, hydrolysis, and the like.

  The production of polylactic acid mainly comprises four steps of saccharification, fermentation, purification and polymerization. The raw material is starch that can be produced from plant-derived raw materials such as sugar cane and corn. Lactic acid can be obtained by further fermenting glucose obtained by saccharifying this starch. From this lactic acid, lactide which is a cyclic dimer is produced through esterification and polymerization, and polylactic acid is produced by ring-opening polymerization.

  Thus, oligolactic acid is produced from plant-derived materials and is the same natural material as mineral materials. That is, it can be considered that the molding composition of the present invention is composed of natural raw materials.

  Moreover, in the baking for solidifying the molded product molded using the molding composition, oligolactic acid can serve as a binder by forming fine powder particles. Thus, it becomes a state mixed with aggregate etc. by making oligolactic acid into the oligolactic acid particle | grains which are microparticles | fine-particles. For this reason, oligolactic acid particles are used for the molding composition. The molding composition contains aggregate and clay, and these are mixed in the kneading process. In firing, fine powder particles of mixed aggregate and clay need to be joined to each other. The oligolactic acid particles play a role of joining the fine particles of the aggregate and the fine particles of the clay to each other.

  The mechanism of bonding between the powder particles is considered as follows. When the aggregate, clay, and oligolactic acid particles are blended and an appropriate amount of water is added to the particles and mixed thoroughly, the respective components are mixed homogeneously. In other words, oligolactic acid particles entered between aggregate particles and aggregate particles, clay particles and clay particles, aggregate particles and clay particles, and ideally, oligolactic acid particles entered between all natural raw material particles. It becomes a state. Oligolactic acid particles have carboxyl groups and hydroxyl groups generated by hydrolysis on their surfaces, and these hydrophilic groups form hydrogen bonds with hydroxyl groups on the surfaces of aggregate particles and clay particles.

  Thus, the constituent particles of the molding compound are in a state of being bonded to each other by the oligolactic acid particles. When further heat is applied to the molded body, the oligolactic acid particles become molten at around 170 ° C., and the natural raw material particles come into close contact with each other, and are formed between the oligolactic acid particles and the natural raw material particles before and after. In addition, a hydrophilic group in a hydrogen bond state undergoes dehydration condensation and changes to a stronger covalent bond as a bond state. As described above, the polylactic acid between the natural raw material particles changes so as to be combined more strongly than the natural raw material particles due to the change to the molten state and the increase in the binding force between the natural raw material particles. As a result, it is considered that the strength of the molding composition (molded product) after the heat treatment is increased.

  Moreover, the articles | goods obtained by this solidification have the same aspect and the same characteristic as the daily necessities and crafts only with the conventional natural raw material. That is, by mixing oligolactic acid particles, it is possible to produce an article that is the same as an article produced from only a natural raw material, while reducing the proportion of the natural raw material required by the molding composition.

  As described above, the oligolactic acid particles can (1) reduce the ratio of natural raw materials in the molding composition to cope with problems and environmental burdens associated with mining natural raw materials from the natural world. As a result, it works as a binder for aggregates and clays, and realizes the strength and durability of the products obtained by firing. (3) While reducing the proportion of natural materials, the products and the appearances made only from natural materials In this case, it is possible to produce an inferior article.

  As described above, the molding composition according to the embodiment can produce an article similar to an article produced using only a conventional natural raw material while reducing natural raw materials that are a problem of environmental burden.

  Next, details of each element and various variations will be described.

(Oligolactic acid)
Oligolactic acid is obtained by pulverizing waste plastic in a predetermined process. This predetermined process includes a decomposition process using heated steam. In modern society, various plastic products are overflowing, and there is a problem that these are discarded and become a large amount of garbage. When waste plastic is incinerated, it generates toxic gas or carbon dioxide, which causes an environmental load. Or the plastic generally used for containers and packaging has a large volume when discarded, and if it is landfilled as it is, it leads to further promoting the landfill shortage which has become a social problem.

  The disposal and disposal of such plastic waste has become a major social problem.

  Oligolactic acid is obtained by pulverizing the waste plastic in addition to the virgin raw material through a superheated steam treatment. That is, oligolactic acid mixed with the molding composition is a substance obtained by recycling and effectively using waste plastics that were originally discarded. As explained above, oligolactic acid is obtained by degradation of polylactic acid.

  Here, oligolactic acid is different from polylactic acid. Polylactic acid has a degree of polymerization of 500 or more and a molecular weight of 50,000 or more. In contrast, the oligolactic acid used in the molding composition of the embodiment has a degree of polymerization of 2 or more and less than 500. The molecular weight is 180 or more and less than 50,000.

  Thus, oligolactic acid has a smaller degree of polymerization and molecular weight than polylactic acid. In a composition using a polylactic acid polymer proposed in the prior art as a mixture, polylactic acid having a large degree of polymerization and molecular weight is used. On the other hand, in the molding composition in the embodiment, oligolactic acid having a polymerization degree and molecular weight smaller than that of polylactic acid is used.

  As described above, oligolactic acid has a degree of polymerization of 2 or more and less than 500, and a molecular weight of 180 or more and less than 50,000. Of course, as a more preferable range, the oligolactic acid contained in the molding composition of the embodiment has a degree of polymerization of 2 or more and less than 100 and a molecular weight of 180 or more and less than 9000. Furthermore, oligolactic acid may have a degree of polymerization of 2 or more and less than 10 and a molecular weight of 180 or more and less than 1000.

  Thus, the molding composition utilizes oligolactic acid having a smaller degree of polymerization and molecular weight than polylactic acid.

  Oligolactic acid has a smaller degree of polymerization and a lower molecular weight than polylactic acid, and is therefore more brittle and fragile than polylactic acid. That is, oligolactic acid tends to be a powder. On the other hand, since polylactic acid has a high degree of polymerization and molecular weight, it is difficult to break and become a powder. Since the molding composition is processed through a kneading and molding process, it is appropriate that oligolactic acid is mixed with aggregate and clay while being sufficiently dispersed. In the case of polylactic acid, since it is difficult to form a powder, it is difficult to sufficiently disperse and mix in the molding composition.

  On the other hand, since oligolactic acid tends to be fine particles, it is sufficiently dispersed and mixed in the molding composition. As a result, in the molding composition, oligolactic acid can surely reduce the proportion of natural raw materials.

  In addition, as described above, oligolactic acid serves as a binder. For this reason, the role as a binder can be more reliably fulfilled when oligolactic acid is sufficiently dispersed and mixed in the molding composition. By ensuring the role of the binder, the strength of the product can be increased more efficiently than when polylactic acid is mixed.

  Thus, by using oligolactic acid, not only can plastic waste be effectively recycled, but oligolactic acid can bring about superior results in binder function and mixing ratio compared to polylactic acid.

  The molding composition according to the embodiment is an article manufactured by using only natural raw materials while reducing the ratio of natural raw materials by mixing oligolactic acid, which is an artificial raw material manufactured from waste plastic, in addition to natural raw materials. Can be produced.

(Baking temperature)
Moreover, the firing temperature at the time of solidifying a molding composition can be made low by using oligolactic acid.

  A high temperature is required to mold and solidify a molding composition composed only of natural raw materials such as aggregates and plastic raw materials. For example, the unglazed temperature of ceramics is generally around 900 ° C., and it is necessary to fire at a temperature around 1300 ° C. in order to densify the ceramic. Also, the firing time is very long and depends on the size and shape of the article to be manufactured. For example, in the case of a doll made of clay, a firing time of about 10 hours is required.

  The necessity of such a high firing temperature and a long firing time brings about an environmental load such as energy consumption (fuel consumption) accompanying firing and emission of carbon dioxide generated by firing. Moreover, a high baking temperature and a long baking time also cause extra labor for the manufacturer.

  On the other hand, the molding composition in the embodiment contains oligolactic acid, and as described above, oligolactic acid adheres between constituent particles as a binder. That is, aggregate particles and clay particles, or aggregate particles and clay particles are bonded together by adhesion.

  Further, the molding composition solidifies more reliably by firing. As described above, oligolactic acid particles have carboxyl groups and hydroxyl groups generated by hydrolysis on their surfaces, and these hydrophilic groups form hydrogen bonds with hydroxyl groups on the surfaces of aggregate particles and clay particles. doing. That is, the constituent particles of the molding compound are bonded to each other by oligolactic acid particles, and when this molded body is further heated, hydrophilic groups such as carboxyl groups and hydroxyl groups of oligolactic acid are hydrogen bonded. It is considered that dehydration condensation is performed with hydroxyl groups on the natural raw material particles in a state, and as a result, the natural raw material particles are more strongly bonded via the oligolactic acid particles.

  On the other hand, a conventional general ceramic clay made of only natural raw materials is a mixture of quartz, feldspar, clay, or a mixture of quartz, muscovite, clay, but the constituent particles are mainly clay. The particles are bonded to each other due to their properties as a binder. The clay used is mainly kaolin clay minerals, and kaolinite is usually used frequently. Kaolinite not only gives plasticity during the molding of the substrate, but also irreversibly dehydrates the crystal water during the firing process, so that even if the unglazed product absorbs water, the constituent particles re-disperse in the water. This prevents the unglazed product from collapsing. Thus, the base material comprised only with a natural raw material is maintaining the unbaking intensity | strength mainly by adhesion | attachment by a clay particle by baking at unbaking temperature.

  As described above, in the molding composition in the embodiment, since oligolactic acid plays a role of a binder, the firing temperature for solidification may be low. Actually, the firing temperature required for solidification of the molding composition is sufficient in the range of 160 ° C to 220 ° C. This is because the melting temperature of oligolactic acid is low.

  In addition, since the oligolactic acid serves as an adhesive, not only the temperature required for solidification but also the firing time can be shortened. Since the firing temperature is low and the firing time can be shortened, the environmental burden can be reduced when manufacturing various articles such as ceramics, daily necessities, crafts, and building materials using the molding composition.

  Oligolactic acid has a smaller polymerization degree and molecular weight than polylactic acid. For this reason, oligolactic acid is uniformly and widely dispersed in the molding composition. That is, oligolactic acid comes to be uniformly dispersed in the gaps between the aggregate and clay powder inside the molding composition. As a result, oligolactic acid can be melted in a more uniform and dispersed state than in the case of polylactic acid to bond aggregate or clay.

  In addition, oligolactic acid is smaller than polylactic acid in terms of polymerization degree and molecular weight, so that the melting temperature due to combustion heat is also lowered.

  Together, oligolactic acid can achieve solidification of the molding composition at a lower firing temperature than polylactic acid. As described above, oligolactic acid is easily broken and becomes a fine powder when it is included in the molding composition, so that it is uniformly and widely dispersed and mixed. By this dispersion and mixing, the degree of adhesion to the aggregate and clay is increased, and it can be solidified at a low firing temperature and a short firing time.

(aggregate)
Aggregate is a main raw material of the molding composition and is a component that becomes a skeleton of the molding composition.

  The aggregate may be mined from the natural world, and the natural raw material mined from the natural world may be separated and the aggregate may be taken out and used. Or the natural raw material mined from nature is added to the molding composition of embodiment. Aggregate contained in the natural raw material becomes a component of the aggregate of the molding composition.

  Thus, the aggregate which the molding composition of embodiment contains may be mixed independently as a component, and may be mixed with the natural raw material containing aggregate.

  As long as the aggregate is a particle that can form a filled structure and maintain its shape in the structure of the molded product when the molding composition is molded and processed, any mineral can be used. In the case of clay, quartz or feldspar is actually suitable. By the way, feldspar in porcelain works when it is baked at a high temperature (usually around 1300 ° C) at which porcelain is porcelain, it melts itself and dissolves clay components in it. Therefore, it is treated as a solvent medium. On the other hand, the molding composition of the present application is fired at 160 ° C. to 220 ° C. and functions as an aggregate because it is much lower than the melting temperature of feldspar. Quartz and feldspar are abundant as natural raw materials and can be easily mined, and a sufficient amount can be used as a main component of the molding composition.

  Quartz, one of the aggregates, can be obtained from various natural raw materials. This natural source can vary. However, when the molding composition is used as a ceramic clay rooted in a region, it is also preferable that quartz derived from a natural raw material produced in the region is used as an aggregate.

  For example, it is also preferable that quartz or feldspar used as an aggregate is derived from a natural raw material called Amakusa pottery stone. This is because Amakusa pottery stone has a large minable amount and contains quartz or feldspar as a component and is suitable for use as a molding composition.

  Here, the molding composition in the embodiment may contain quartz separated from Amakusa pottery stone as an aggregate. Alternatively, Amakusa pottery stone itself may be mixed to contain quartz as an aggregate.

  Of course, Amakusa porcelain stone was mentioned here as an example for blending the aggregate components, but aggregates derived from other natural raw materials may be used, and separated from natural raw materials etc. The resulting aggregate may be used. These are mixed with other raw materials, and the molding composition in embodiment is obtained.

(clay)
Clay can impart fluidity when kneading an appropriate amount of moisture in the molding composition and plasticity when molding. In addition, after drying the molding composition, it is possible to bring about an adhesive effect by the fine clay particles, and therefore, in combination with the adhesive effect by the oligolactic acid particles, contributes to maintaining high mechanical strength of the article.

  Thus, the clay causes the plasticity of the molding composition in the production stage. For this reason, although clay is poor in the function of forming the skeleton of an article produced by the molding composition, it can enter between the aggregate particles and the oligolactic acid particles and give plasticity to the entire molding composition.

  Similarly to the aggregate, clay may be mixed with the molding composition in the embodiment as a natural raw material mined from the natural world. Alternatively, natural raw materials such as porcelain stone containing clay as a component may be directly mixed with the molding composition. This is because, in any case, clay is mixed as a component of the molding composition.

  As an example, the clay is also preferably kaolin clay or muscovite containing a kaolin mineral as a main component. Kaolin clay with excellent plasticity includes Kibushi clay and Sasame clay in Japan. Besides kaolin clay like Amakusa pottery stone, there are porcelain stones that are not kaolin clay but contain muscovite with plasticity. .

  In addition, porcelain stones are processed into porcelain without adding coarse natural quartz components by means such as water poultry without blending other natural raw materials. In addition, Nanakuma clay, which is widely used for some dolls, is composed of quartz, kaolinite, and muscovite as well as Amakusa porcelain (a porcelain clay made from Amakusa porcelain stone). It is suitable to be used as a raw material for the molding composition as in This is because the plasticity of kaolin mineral and muscovite is suitable for the purpose of the molding composition in the embodiment containing clay as a component.

It is also preferable to use kaolin derived from New Zealand kaolin. New Zealand Kaolin is mainly composed of kaolin mineral halloysite. This halloysite is also a highly plasticized clay. In addition, since kaolin derived from New Zealand kaolin has high whiteness, one of the reasons for using this clay is that whiteness of the resulting molding composition is increased.
British SP kaolin is also suitable for use as the clay in the molding composition. The main component of British SP kaolin is kaolinite, but like New Zealand kaolin, it is a highly plasticized clay with high whiteness. Therefore, when it mix | blends with the composition for shaping | molding, it contributes to maintaining the whiteness high.

If the whiteness of the molding composition is high, naturally the whiteness of the manufactured article is also increased. In the molding composition in the embodiment, the oligolactic acid serves as a binder, so that the firing temperature can be lowered. For this reason, it is difficult for the whiteness of the article to be reduced by firing. For this reason, if the whiteness of the molding composition is high, the whiteness of the resulting article is also kept high.

  It is preferable that various articles manufactured using the molding composition have high applicability in which design and color are imparted after the manufacture. For this reason, it is preferable that the color of the manufactured article is close to white. This is because if the color is close to white, the subsequent design and color can be easily applied. In addition, the beauty of the assigned design and color stands out.

  Moreover, it is also suitable that it is derived from Kibushi clay as a natural raw clay produced in Japan. Kibushi clay is a natural raw material that is stably produced in Japan, is easy to mine, and is excellent in plasticity, and can improve the moldability and handling strength of the resulting molding composition.

  As described above, the molding composition according to the embodiment contains aggregates, clay, oligolactic acid and an inevitable mixture, so that various articles can be produced at a low firing temperature while reducing the ratio of natural raw materials. As a result, it is possible to reduce the environmental load at various stages and viewpoints.

  It should be noted that the aggregate, clay, and oligolactic acid may be basically composed of a mixture of fine powder particles, so that the molding composition may be configured. However, the specific method is basically a natural raw material. This is accomplished by adding oligolactic acid to the aggregate and clay and mixing them homogeneously.

(Experimental result)
Next, the inventor actually produced the molding composition described in the embodiment, and conducted an experiment on the relationship between the bending strength, the whiteness, the firing temperature, and the bending strength. In the experiment, the aggregate and the clay were tested by producing a plurality of samples by using materials of various origins.

(Experiment 1: Experiment with Sample 1 to Sample 5)
In Experiment 1, a molding composition mainly composed of aggregates obtained from general Amakusa porcelain clay was used.

  The inventor manufactured a molding composition containing aggregate, clay, and oligolactic acid, and provided a molding process and a baking process to finally produce a fired product. Table 1 shows the composition of the molding compositions of Sample 1 to Sample 5 used in Experiment 1. That is, in Table 1, the molding compositions that differ depending on the component ratio of aggregate, clay and oligolactic acid or the origin of aggregate and clay are shown for each sample from sample 1 to sample 5.

  The natural raw material used for blending each sample is calculated by the norm calculation based on the chemical analysis values and the constituent minerals clarified by X-ray diffraction. Norm is a hypothetical mineral composition calculated according to certain rules from the chemical composition of natural raw materials. Here, the chemical components of natural raw materials are quartz, feldspar, kaolinite, sericite. The percentage of minerals is calculated by assigning to either of these.

  Based on this calculation result, mass% of aggregate (total amount of quartz and feldspar) and clay (total amount of kaolinite and muscovite) in each sample is obtained. In Table 1, samples of Amakusa porcelain A added with oligolactic acid (Sample 1), samples containing Aggregate, Clay, and oligolactic acid (Sample 2 and Sample 3), and Nanakuma Clay A and Nanakuma Clay B The sample (sample 4, sample 5) which added lactic acid is shown.

  As shown in Table 1, the samples manufactured by the inventors are as follows.

  (Sample 1) Aggregate: 36.7 wt%, clay: 49.8 wt%, oligolactic acid: 13.5 wt%, aggregate and clay are derived from Amakusa porcelain clay A.

  (Sample 2) Aggregate: 56 wt%, clay: 33 wt%, oligolactic acid: 11.1 wt%, clay is derived from New Zealand kaolin.

  (Sample 3) Aggregate: 56 wt%, clay: 33 wt%, oligolactic acid: 11.1 wt%, clay is derived from Kibushi clay.

  (Sample 4) Aggregate: 21.2 wt%, clay 68.3 wt%, oligolactic acid: 10.5 wt%, and clay is derived from Nanakuma clay A.

  (Sample 5) Aggregate: 17.2 wt%, Clay 72.3 wt%, Oligolactic acid 10.5 wt%, Aggregate and clay are derived from Nanakuma Clay B.

  As described above, the ratio of each component of Sample 1 to Sample 5 is obtained by calculation from the chemical analysis of raw materials and the identification of constituent minerals by X-ray diffraction.

  Each of Sample 1 to Sample 5 is actually subjected to a molding (casting) step and a firing step (held at 200 ° C. for 1 h), and each of Samples 1 to 5 is a cylindrical sample (diameter of about 10 mm, for bending strength measurement). A plate-like sample (length: about 50 mm, width: about 50 mm, thickness: about 10 mm) for measuring whiteness and whiteness was obtained.

  Furthermore, the whiteness measured by the colorimeter in each of Sample 1 to Sample 5 was also measured. Table 2 shows the measurement results of the bending strength and the whiteness of Samples 1 to 5.

  As is clear from the results in Table 2, all of the samples 1 to 5 exceed 8 MPa, which is the bending strength of unglazed baking obtained using general natural ceramic clay. The inventors used a cylindrical sample obtained by casting and molding Amakusa porcelain in the same manner as described above and firing at 920 ° C. as unglazed obtained using general natural porcelain.

  Moreover, all of the samples 1 to 5 were fired at a temperature of 160 ° C to 220 ° C. That is, it can be fired at a temperature that is much lower than that required for firing of natural clay clay. In spite of firing at this very low temperature, it can be seen that it has a higher bending strength than the unglazed natural porcelain fired at about 920 ° C. This not only indicates that the bending strength is sufficient, but also indicates that the manufacturing cost, manufacturing burden, and environmental load in firing can be reduced. As described above, the molding compositions according to Embodiments 1 and 2 can also solve the problems and problems of the prior art from the results of actual production.

  Table 2 also shows the whiteness. The whiteness of Amakusa pottery ware is shown as a reference value of whiteness, but the whiteness of Sample 1 and Sample 2 is much higher than that of Amakusa pottery ware. In particular, Sample 1 has a value as high as 5% despite using the same Amakusa porcelain clay. This is because when porcelain is baked, it becomes reddish due to oxidation of iron contained in the porcelain. This is to avoid a decrease in whiteness due to oxidation of iron.

Since Sample 2 uses New Zealand kaolin with low iron content as clay, its whiteness is 5% higher than Sample 1. On the other hand, the whiteness of Sample 3 and Sample 4 is only about 75%, which is due to the low whiteness of Kibushi clay and Shichijo clay used as raw materials. The bending strength of the fired product is a property that affects the mechanical durability of the product, and is particularly important for large products from the viewpoint of suppressing breakage due to its own weight or handling. Also, whiteness is important from the viewpoint of reducing the necessity / unnecessity of undercoating and the effect of coloring on the background when coloring products. In the result of Table 1, it is excellent in either bending strength or whiteness, and the manufacture of the product which utilizes each advantage is possible with the molding composition in embodiment.
(Experiment 2: Experiment with Samples 6-10)

  Next, Sample 6 to Sample 10 of the molding composition using aggregates and clays having different origins from Table 1 were prepared, and Experiment 2 was performed. Table 3 shows the component compositions of Sample 6 to Sample 10. Samples 6 and 7 are molding compositions in which clay and oligolactic acid are added to the reduced degree Amakusa porcelain clay B with a small amount of clay components. Samples 8 to 10 are molding compositions obtained by adding oligolactic acid to Amakusa porcelain clay C with a high iron content.

Experiment 2 is different from Experiment 1 in that it confirms the bending strength and whiteness of the molding composition different from the variation in Experiment 1 in which natural clay is originally used in aggregate and clay.

  Samples 6 to 10 are as follows.

  (Sample 6) Aggregate: 37 wt%, clay: 53 wt%, oligolactic acid: 10 wt%. Aggregate is derived from Amakusa porcelain clay B (decreasing degree), and clay is derived from Amakusa porcelain clay B (decreasing degree) and British SPK kaolin.

  (Sample 7) Aggregate: 34 wt%, clay: 51 wt%, oligolactic acid: 15 wt%. Aggregate is derived from Amakusa porcelain clay B (decreasing degree), and clay is derived from Amakusa porcelain clay B (decreasing degree) and British SPK kaolin.

  (Sample 8) Aggregate: 29 wt%, clay: 56 wt%, oligolactic acid: 15 wt%. Aggregate and clay are derived from Amakusa Porcelain C (rich in iron and clay).

  (Sample 9) Aggregate: 28 wt%, clay: 54 wt%, oligolactic acid: 18 wt%. Aggregate and clay are derived from Amakusa Porcelain C (rich in iron and clay).

  (Sample 10) Aggregate: 42 wt%, clay: 43 wt%, oligolactic acid: 15 wt%. Aggregate and clay are derived from Amakusa porcelain clay D (rich in iron and low in clay).

The bending strength and whiteness of the moldings obtained by subjecting each of the molding compositions of Sample 6 to Sample 10 to the above-described casting and firing steps (baking at 200 ° C. for 1 hour) were measured. The measuring method and the like are the same as those described in Table 2. The measurement results are shown in Table 4.

  Samples 6 and 7 are samples prepared by blending Amakusa porcelain B (decreasing degree porcelain clay with 38% clay content) with British SP kaolin having excellent whiteness. When the compounding amount of SP kaolin was increased to 10 wt% and 15 wt%, the bending strength of the sample increased to 6: 14.5 MPa and 7:16 MPa. The bending strength of the sample 7 is twice that of 8 MPa of Amakusa pottery ware.

  Samples 8 and 9 are samples obtained by adding 15 wt% and 18 wt% of oligolactic acid to Amakusa porcelain clay C (65% clay, 0.6% iron), respectively. The bending strength of the sample was 21.1 MPa and 23.3 MPa, which was the maximum among the samples. The bending strength of sample 9 is about three times that of Amakusa pottery ware. On the other hand, the whiteness was 8: 84.3% of the sample and 9: 85% of the sample, which was similar to Amakusa pottery ware.

  Sample 10 is a sample obtained by adding 15 wt% oligolactic acid to Amakusa porcelain clay D (43% clay, 0.5% iron). Sample 10 had a bending strength of 16.9 MPa and a whiteness of 87.2 MPa.

As mentioned above, Amakusa porcelain clay with different grades, or Amakusa porcelain with British SP kaolin added to it, solidified at low temperature by adding oligolactic acid, approximately 2-3 times the bending strength of Amakusa porcelain clay Thus, a molding composition having a whiteness equivalent to that of Amakusa pottery ware or 6 to 7% higher can be obtained.
As is clear from Experiment 2, even when there are variations in the origin of aggregates and clay, the molding composition in the embodiment can produce a practically sufficient molded product.

(Experiment 3: Confirmation of firing temperature range)
Next, the inventor conducted an experiment as Experiment 3 to examine the optimum range of the firing temperature of the molding composition in the embodiment.

  A sample 11 prepared by adding 10 wt% oligolactic acid to 90 wt% of Amakusa porcelain clay (decrease degree: 38% clay) is a cylindrical sample (diameter: about 10 mm, length: about 10 mm). 80 mm), dried at 100 ° C., and fired at 160 ° C., 180 ° C., 200 ° C., and 220 ° C. for 1 hour. That is, four types of molded articles having different firing temperatures were produced. Here, a molded product fired at 160 ° C. is sample 1, a molded product fired at 180 ° C. is sample 2, a molded product fired at 200 ° C. is sample 3, and a molded product fired at 220 ° C. is sample 4.

  When the bending strengths of Sample 1 to Sample 4 were measured, they were as follows.

Sample 1: 6.2 MPa
Sample 2: 9.2 MPa
Sample 3: 10.6 MPa
Sample 4: 10.1 MPa

  As described above, the bending strength of the sample 11 increases as the firing temperature increases, as shown by the samples 1 to 4. Actually, the bending strength was the maximum in sample 3 having a firing temperature of 200 ° C., and the bending strength was slightly reduced in sample 4 having a firing temperature of 220 ° C.

  As described above, the molding composition using the oligolactic acid as a binder in the embodiment has a firing temperature of 160 ° C. to 220 ° C., more preferably 180 ° C. to 220 ° C., which is the optimum temperature range from the viewpoint of bending strength. It is thought that. Of course, a good result in bending strength indicates that durability and use strength are also good.

  On the other hand, the firing temperature of general unglazed baking using natural porcelain is about 900 ° C. Compared to the firing temperature of about 900 ° C., the firing temperature of 180 ° C. to 220 ° C. is extremely low. In other words, when the molding composition described in the embodiment is baked into a molded product, the manufacturing cost, the manufacturing burden, and the environmental burden (in terms of energy consumption, carbon dioxide generation, etc.) can be reduced. There is.

  From the above, the molding composition containing oligolactic acid as its component can be given higher bending strength than natural ceramic clay by firing at a low temperature of around 200 ° C. Since the coloration due to can be avoided, the whiteness of the fired product can be a much higher numerical value. As a result, the molding composition in the embodiment can be used as a material for various articles such as ceramics, daily necessities, crafts, and building materials.

  As described above, the molding composition described in the embodiment is an example for explaining the gist of the present invention, and includes modifications and alterations without departing from the gist of the present invention.

Claims (13)

  A molding composition containing aggregate, clay, oligolactic acid and an unavoidable mixture, and used for producing a predetermined article.   The molding composition according to claim 1, wherein the oligolactic acid has a degree of polymerization of 2 or more and less than 500.   The molding composition according to claim 1, wherein the oligolactic acid has a molecular weight of 180 or more and less than 50,000.   The molding composition according to any one of claims 1 to 3, wherein the oligolactic acid is obtained by pulverizing waste plastic in a predetermined step.   The molding composition according to claim 4, wherein the predetermined step includes a decomposition treatment with superheated steam.   The molding composition according to claim 1, wherein the predetermined article is any one of ceramics, daily necessities, crafts, and building materials.   The molding composition according to claim 1, wherein the aggregate is quartz or feldspar.   The molding composition according to claim 7, wherein the quartz or feldspar is derived from natural ceramic stone.   The molding composition according to claim 1, wherein the clay is kaolin clay or muscovite containing a kaolin mineral as a main component.   The molding composition according to claim 1, wherein the kaolin clay is kaolin clay derived from Kibushi clay, New Zealand kaolin, or British SP kaolin.   11. The molding composition according to claim 1, wherein the clay is kaolin clay or muscovite derived from Amakusa porcelain clay or Shichijo clay.   A molded product obtained by subjecting the molding composition according to any one of claims 1 to 11 to a molding step and a firing step.   The molded product according to claim 12, wherein the firing temperature in the firing step is 160 ° C to 220 ° C, more preferably 180 ° C to 220 ° C.