Method for manufacturing interior and exterior building materials and interior and exterior building materials

Abstract

The present invention provides a method for manufacturing interior and exterior building materials that are reusable earth-molded bodies with sufficient strength for practical use, and provides interior and exterior building materials that are reusable earth-molded bodies with sufficient strength for practical use. [Solution] A method for manufacturing interior and exterior building materials and interior and exterior building materials, comprising the steps of: kneading soil, polyvinyl alcohol in an amount of 0.1% to 10% by mass relative to the total mass of the soil to obtain a mixture; and molding and solidifying the obtained mixture to obtain a soil molded body.

Description

[Technical Field]

[0001] This disclosure relates to a method for manufacturing interior and exterior building materials and to interior and exterior building materials. [Background technology]

[0002] Soil has traditionally been used as a building material, but the strength of soil molded products as solidified materials is insufficient, and they have problems with low water resistance. In addition, when soil is mixed with water and kneaded to form soil molded products, cracks occur due to shrinkage during the drying process. In recent years, attempts have been made to recycle construction waste soil from the perspective of energy conservation and reducing the environmental burden caused by construction waste. However, as mentioned above, molded soil bodies lack sufficient strength for use as building materials. Therefore, hydraulic materials such as cement are mixed in as solidifying agents. However, building materials containing cement are not biodegradable, raising concerns that a new disposal problem will arise after the building materials are used. For example, as a method for reusing dredged soil, a technique has been proposed in which a coagulation agent is added to the dredged soil to obtain a preliminary solid, the preliminary solid is separated into solid and liquid to adjust the water content, and a vinyl alcohol-based resin and / or soil conditioner are added to the obtained solid as a secondary additive to obtain a solid, which is then dried to produce a water-resistant marine block (see Patent Document 1). Furthermore, a method for obtaining a filler material for potted plant cultivation has been disclosed, which involves adding a vinyl alcohol-based resin as an adhesive and a saponifying agent to soil material and kneading them together (see Non-Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2006-325515 [Non-patent literature]

[0004] [Non-Patent Document 1] Kochi University Academic Research Report Vol. 13 Natural Science II No. 8 P211: 1954 "Research on Filling Materials for Potted Plant Cultivation (1)" [Overview of the project] [Problems that the invention aims to solve]

[0005] While the manufacturing method described in Patent Document 1 yields marine blocks with low environmental impact, the manufacturing process is complicated, and the applications of the blocks are limited. Furthermore, Patent Document 1 does not address the recycling of the blocks, which are molded soil products. Furthermore, while the molded soil obtained by the method described in Non-Patent Document 1 can be used as a filler for flowerpots for water retention purposes, it is difficult to obtain molded soil of the desired size, and the resulting molded soil is not strong enough to be used as a building material.

[0006] The object of one embodiment of this disclosure is to provide a method for manufacturing interior and exterior building materials, which are reusable soil molded bodies with sufficient strength for practical use. Another embodiment of the present disclosure aims to provide an interior and exterior building material that is a reusable soil-molded body with sufficient strength for practical use. [Means for solving the problem]

[0007] The means for solving the above problem include the following embodiments.

[0008] <1> A process of kneading soil, vinyl alcohol-based resin in an amount of 0.1% to 10% by mass relative to the total mass of the soil, and water to obtain a mixture, The process includes molding and solidifying the resulting mixture to obtain a clay molded body. A method for manufacturing interior and exterior building materials. <2> The mixture further contains an antifoaming agent. <1> A method for manufacturing interior and exterior building materials as described above. <3> The kneading in the process of obtaining the aforementioned mixture is carried out using a kneader equipped with a degassing device. <1> A method for manufacturing interior and exterior building materials as described above.

[0009] <4> This is a soil-based molded body containing soil and vinyl alcohol-based resin in an amount of 0.1% to 10% by mass relative to the total mass of the soil, and having a compressive strength of 1 N / mm² as measured under the following compressive strength measurement conditions. 2 Furthermore, the bending strength measured in accordance with JIS R5201:2015 is 1 N / mm². 2 That concludes the description of interior and exterior building materials. (JIS is an abbreviation for Japanese Industrial Standards. The same applies hereafter.) (Compressive strength measurement conditions) Using a cylindrical mold measuring φ20mm x height 40mm, a cylindrical clay body is obtained. The parts of both ends that come into contact with the formwork are capped with epoxy resin. The obtained cylindrical test specimens are subjected to compression strength testing using a compression strength tester of grade 1 or higher, in accordance with the provisions of JIS B7721:2012. [Effects of the Invention]

[0010] According to one embodiment of this disclosure, a method for manufacturing interior and exterior building materials, which are reusable soil-molded bodies with sufficient strength for practical use, can be provided. According to another embodiment of the present disclosure, it is possible to provide interior and exterior building materials that are reusable earth molded bodies with sufficient strength for practical use. [Modes for carrying out the invention]

[0011] The contents of this disclosure will be explained in detail below. These descriptions and examples illustrate embodiments of the present disclosure and do not limit the scope of the embodiments. In this disclosure, the numerical range indicated using "~" represents a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions. Also, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. Unless otherwise specified, each component in the composition in the present disclosure may be included alone or in combination of two or more. In the present disclosure, the amount of each component in the composition means the total amount of the corresponding plurality of substances present in the composition when there are a plurality of each component in the composition, unless otherwise specified. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

[0012] In the present disclosure, "total solid content" refers to the total mass of the components obtained by removing the solvent from the entire composition of the composition. Also, "solid content" is a component obtained by removing the solvent as described above, and the component may be, for example, solid or liquid at 25°C. "Room temperature" means the ambient temperature not particularly controlled for temperature, and in the present disclosure, it refers to "25°C" unless otherwise specified. In the present disclosure, polyvinyl alcohol may be described as "PVA", and vinyl alcohol-based resin may be described as "PVA-based resin". The "PVA-based resin" in the present disclosure refers to a resin containing at least one kind of PVA, and is used in the sense of including not only resins containing unmodified PVA but also PVA resins containing various modified PVAs.

[0013] <Method for manufacturing interior and exterior building materials> The method for manufacturing interior and exterior building materials of the present disclosure includes a step (step 1) of kneading soil, a vinyl alcohol-based resin in an amount of 0.1% by mass to 10% by mass based on the total mass of the soil, and water to obtain a mixture, and a step (step 2) of molding and solidifying the obtained mixture to obtain a soil molded body.

[0014] In this disclosure, "soil molded body" refers to a solidified product of a mixture obtained by kneading soil, a predetermined amount of vinyl alcohol-based resin with soil, and water, and which contains soil as the main component. Here, "main component" refers to the component that makes up 50% by mass or more of the total solids contained in the mixture. The amount of soil contained in the mixture is preferably 60% by mass or more, and more preferably 80% by mass or more, relative to the total solids contained in the mixture.

[0015] [Process 1] In step 1 of this disclosure, soil, vinyl alcohol-based resin in an amount of 0.1% to 10% by mass relative to the total mass of the soil, and water are kneaded together to obtain a mixture. The following describes each component used in the preparation of the mixture.

[0016] (soil) In step 1 of this disclosure, there are no particular restrictions on the soil used to prepare the mixture, and it can be appropriately selected from known soils such as cohesive soil, sandy soil, and organic soil. Furthermore, construction waste and soil generated by excavation can also be used without restriction. By using construction waste and other excavated soil as the source of the soil, it becomes possible to supply locally produced raw materials and further reduce the environmental impact. When using construction waste soil, if the construction waste soil contains relatively large lumps of soil, gravel, metal fragments, or other solid impurities, it may be difficult to uniformly mix the soil with the PVA resin in step 1. Therefore, it is advisable to remove lumps of soil, gravel, impurities, etc., of, for example, 5 mm or larger by sieving before use.

[0017] (Vinyl alcohol-based resin: PVA-based resin) In preparing the mixture, 0.1% to 10% by mass of PVA resin is used relative to the total mass of the soil. We believe that by mixing PVA resin, a water-soluble polymer, with soil to prepare the mixture, the water-dissolved PVA resin penetrates between the soil particles, acting as a binder and proving effective in forming soil molded bodies. There are no particular restrictions on the PVA resin; any PVA resin that can dissolve in water at 25°C at a concentration of 1% by mass or more is acceptable. The PVA contained in the PVA-based resin may be fully saponified or partially saponified. In particular, a PVA-based resin containing PVA with a degree of saponification in the range of 70.0 mol% to 99.9 mol% is preferred from the viewpoint of improving the strength of the resulting clay molded product, and a degree of saponification of PVA in the range of 80.0 mol% to 99.5 mol% is more preferred. Generally, as the degree of saponification of PVA resin decreases, its water solubility decreases, making it less soluble in water. A partial saponification of the PVA resin within the above range is preferable because it facilitates the preparation of a homogeneous mixture in step 1. As PVA-based resins, unmodified PVA, carboxylic acid-modified PVA, acetoacetyl-modified PVA, ethylene-modified PVA, cation-modified PVA, sulfonic acid-modified PVA, and ethylene oxide-modified PVA can also be used. For example, using a resin containing carboxylic acid-modified PVA as the PVA-based resin is preferable because it improves compatibility with water during the preparation of the mixture, making it easier to obtain a homogeneous mixture.

[0018] The average degree of polymerization of the PVA contained in the PVA-based resin is preferably 300 to 4000, more preferably 1000 to 3000, and even more preferably 1600 to 2000, from the viewpoint of obtaining a more uniform mixture.

[0019] The degree of saponification and the average degree of polymerization of PVA can be measured in accordance with JIS K 6726:1994 "Test Methods for Polyvinyl Alcohol". Commercially available PVA resins may be used. When using a commercially available product, a PVA resin exhibiting appropriate saponification and average polymerization levels according to catalog values ​​may be selected.

[0020] The PVA resin used in step I may be a single type, or two or more types with different viscosity, average degree of polymerization, degree of saponification, etc., may be used in combination. When two or more types of PVA resin are used in combination, it is preferable that the average values ​​of the degree of polymerization and the average values ​​of the degree of saponification of the multiple types of PVA resins are within the above range. The PVA resin content in the soil is preferably 0.1% to 10% by mass relative to the total mass of the soil, more preferably 0.5% to 9% by mass, and more preferably 1.0% to 8% by mass. When the PVA resin content relative to the total mass of the soil is within the above range, a uniform mixture can be easily prepared, resulting in better strength and water resistance of the resulting soil molded body.

[0021] (water) In step 1, water is used when preparing the mixture. There are no particular restrictions on the water used in step 1. When preparing a homogeneous mixture by mixing the aforementioned soil with a predetermined amount of PVA resin, there are no particular restrictions as long as the conditions such as not containing harmful substances and not impairing the solubility of the PVA resin are met. Tap water, deionized water, purified water, recycled water, stored rainwater, etc., can be appropriately selected, and tap water is preferred from the viewpoint of having fewer impurities. By appropriately controlling the water content, solidified material can be obtained in a shorter time and uniform mixing can be performed, resulting in a solidified material with good strength. From that perspective, it is preferable to adjust the mass of water depending on the physical properties of the soil used in step 1. Specifically, the water content in the mixture is preferably less than or equal to the plastic limit Wp% + 10% obtained from the plastic limit test (consistency characteristic value) of the soil. The plasticity limit test of soil can be performed in accordance with JIS A1205:2020. By measuring the plasticity limit of the soil used, it is possible to determine the appropriate water content corresponding to the plasticity limit of the soil. By setting the water content of the soil to the plastic limit Wp% + 10% or less, the moisture content becomes appropriate, resulting in better moldability when molding the mixture. There is no particular limit on the lower limit of the water content. It should be selected appropriately depending on the properties of the soil used and the type of PVA resin used. In one embodiment, the amount should be adjusted so that it can be uniformly mixed when kneading the mixture.

[0022] (Other ingredients) When preparing the mixture in step 1, in addition to the soil, PVA resin, and water described above, known additives may be used to the extent that they do not impair the effect. Other components include, for example, defoaming agents, surfactants, fluidity improvers, reinforcing agents, fillers, plasticizers, pigments, dyes, lubricants, antioxidants, antistatic agents, UV absorbers, heat stabilizers, light stabilizers, antibacterial agents, antistatic agents, drying agents, antiblocking agents, flame retardants, crosslinking agents, curing agents, foaming agents, and crystal nucleating agents. The mixture preferably further contains an antifoaming agent. The inclusion of an antifoaming agent in the mixture is preferable because it suppresses the generation of air bubbles when mixing soil, PVA resin, and water. From the perspective of uniform mixing, extending the mixing time may result in the incorporation of air bubbles during mechanical mixing. Mixtures containing air bubbles are more prone to deformation during drying and solidification due to these bubbles. By further including an antifoaming agent in the mixture, the incorporation of unwanted air bubbles into the mixture can be suppressed. Examples of defoaming agents include polycarboxylic acid copolymers, fatty acid or ester-based defoaming agents, alcohol-based defoaming agents, ether-based defoaming agents, and silicone-based defoaming agents. Commercially available defoaming agents may also be used, such as AFK-2 defoaming agent from Takemoto Oil Co., Ltd.

[0023] In step 1, the equipment used during the kneading process when preparing the mixture includes known mixing devices such as kneaders and mixers. In particular, it is preferable that the kneading in the step of obtaining the mixture (i.e., step 1) be carried out using a kneader equipped with a degassing device, because deformation due to air bubbles in the solidified material can be suppressed. An example of a mixer equipped with a degassing device to reduce the generation of air bubbles is the 30L mixer manufactured by Aikousha Seisakusho Co., Ltd. By using the degassing device to mix under a negative pressure of, for example, -0.1 MPa, the incorporation of air bubbles into the mixture is effectively suppressed.

[0024] [Process 2] Step 2 is the process of molding and solidifying the mixture obtained in Step 1 described above to obtain a molded soil body. The mixture obtained in step 1 can be molded by known methods. Generally, these methods include pouring the obtained mixture into a mold of the desired shape and curing it to solidify, or dry press molding the obtained mixture. The shapes of interior and exterior building materials obtained by the manufacturing method of this disclosure include, but are not limited to, block shapes such as rectangular parallelepipeds or cubes, and flat plates suitable for interior materials. The materials can be poured into any formwork to obtain molded earth bodies. The mixture obtained in step 1, containing PVA resin and water, exhibits better fluidity compared to a mixture containing only soil and water. This is thought to be because the water-soluble PVA resin penetrates the voids between soil particles, resulting in improved fluidity compared to a mixture containing only water.

[0025] The mixture poured into the mold is dried by natural drying, heat drying, or other methods, which reduces the moisture content and yields a molded soil product. The curing conditions for the molded soil body by drying are preferably one week or more by natural drying, and more preferably two weeks or more by natural drying. In this embodiment, when performing heat drying, it is preferable to carry it out for 24 to 72 hours at a temperature of 30°C to 80°C.

[0026] Although the mechanism by which the building materials for interior and exterior use obtained by the manufacturing method of this disclosure have superior strength and durability is not clear, in the soil molded body obtained in step 2, the water in the fluid PVA resin aqueous solution is removed by drying, and the dried and solidified PVA resin is present between the soil particles, causing them to adhere closely together. As a result, the PVA resin acts as a binder, improving the adhesion between soil particles compared to soil molded bodies that do not contain PVA resin, and it is believed that the resulting solidified soil molded body has superior strength and water resistance. Although PVA resin is water-soluble, its presence in a dry state between soil particles prevents water from penetrating deep into the soil even when water comes into contact with the surface of the soil molded body. Therefore, we believe that the soil molded body has good water resistance. Furthermore, while conventional soil molded bodies produced using hydraulic materials such as cement are difficult to recycle, the PVA resin used in the interior and exterior building materials of this disclosure is highly biodegradable, making it reusable and recyclable. Therefore, the soil molded bodies of this disclosure can also be expected to reduce the environmental burden. The above mechanism of action is a presumption and does not affect the interpretation of this disclosure.

[0027] The molded earth body obtained through step 2 has good water resistance and is therefore suitable for use as an interior and exterior building material. The building materials for interior and exterior use obtained by the manufacturing method disclosed herein consist of soil and PVA-based resin, and therefore exhibit good biodegradability and recyclability compared to solidified products obtained by solidifying with hydraulic materials such as cement, thus contributing to the reduction of environmental impact. Furthermore, since PVA resin is a water-soluble polymer, there is a concern that its strength may decrease from the surface if it is used as an exterior material and exposed to wind and rain for a long period of time. However, in such cases, it has the advantage that it is easy to dispose of the old exterior building material even if it is replaced with a new one. On the other hand, when molded earth is used as an interior building material such as a wall material, it has good durability and becomes an interior and exterior building material that can withstand long-term use.

[0028] <Building materials for interior and exterior use> The interior and exterior building materials disclosed herein are soil molded bodies containing soil and vinyl alcohol-based resin in an amount of 0.1% to 10% by mass relative to the total mass of the soil. The compressive strength measured under the following conditions was 1 N / mm². 2 Furthermore, the bending strength measured in accordance with JIS R5201:2015 was 0.8 N / mm². 2 That's all. (Compressive strength measurement conditions) Using a cylindrical mold measuring φ20mm x height 40mm, a cylindrical clay body is obtained. The parts of both ends that come into contact with the formwork are capped with epoxy resin. For the obtained cylindrical test piece, measure the compressive strength using a compression strength testing machine of Grade 1 or higher based on the provisions of JIS B7721:2012.

[0029] The interior and exterior building materials of the present disclosure are preferably the interior and exterior building materials obtained by the manufacturing method of the present disclosure described above. Since the interior and exterior building materials of the present disclosure are composed of a soil molding body containing soil and a PVA-based resin, they have good strength and excellent water resistance. The soil, PVA-based resin, and water contained in the interior and exterior building materials are the same as those described in the manufacturing method of the interior and exterior building materials of the present disclosure described above, and the preferred examples are also the same.

[0030] (Preferred physical properties of interior and exterior building materials) (1. Compressive strength) The interior and exterior building materials of the present disclosure are excellent in compressive strength by containing a PVA-based resin in the voids between soil particles. As the compressive strength, the compressive strength measured under the following compressive strength measurement conditions is 1 N / mm 2 or more. (Compressive strength measurement conditions) Use a cylindrical mold with a diameter of 20 mm and a height of 40 mm to obtain a cylindrical soil molding body, Cap the portions of both end faces in contact with the mold with epoxy resin. For the obtained cylindrical test piece, measure the compressive strength using a compression strength testing machine of Grade 1 or higher based on the provisions of JIS B7721:2012. The compressive strength obtained by the above measurement method is 1 N / mm 2 or more, preferably 2 N / mm 2 or more, and more preferably 3 N / mm 2 or more. For example, the compressive strength measured in the same manner for a soil molding body obtained from a mixture containing only water and soil and not containing a PVA-based resin is 0.5 N / mm 2 or less, indicating that the effectiveness of the PVA-based resin is remarkable.

[0031] (2. Flexural strength) Similarly, the interior and exterior building materials disclosed herein have a bending strength of 0.8 N / mm² as measured in accordance with JIS R5201:2015. 2 The above is 1.0 N / mm 2 Preferably, it is 1.1 N / mm 2 It is more preferable that the above conditions are met. For example, the bending strength of a soil molded body obtained from a mixture of only water and soil, without PVA-based resin, measured using the same method, was 0.5 N / mm². 2 The following demonstrates the remarkable effectiveness of PVA-based resin. While the improvement in flexural strength is somewhat lower compared to the improvement in compressive strength, the addition of PVA-based resin is thought to have increased the viscosity of the soil molded body, resulting in a further improvement in flexural strength.

[0032] (3.Water resistance) The interior and exterior building materials of this disclosure preferably have water resistance. As a guideline for water resistance, it is preferable that no change in material is observed after forming the clay body under the following conditions and immersing it in water at room temperature for 60 minutes. (Evaluation conditions for water resistance) The mixture is molded into a rectangular prism shape in a mold measuring 20 mm in length, 20 mm in width, and 10 mm in height, and then air-dried for one week to obtain a molded soil body. Place the resulting soil molded body in a petri dish filled with water and leave it for 60 minutes. When a molded clay body is immersed in water, if its shape does not change after 60 minutes, it is evaluated as having good water resistance. If its shape collapses within 60 minutes, it is evaluated as having poor water resistance. Preferably, the interior and exterior building materials of this disclosure do not show any change in shape after being immersed in water for 60 minutes. For example, when a soil molded body obtained from a mixture of only water and soil, without PVA-based resin, was evaluated using the same method, deformation was observed after 5 minutes. Therefore, the interior and exterior building materials of this disclosure can be evaluated as having good water resistance. [Examples]

[0033] Examples of the fluidized material and its manufacturing method described herein will be given below. It goes without saying that the fluidized material and its manufacturing method described herein are not limited to the examples given below, but encompass various modifications within the scope of their intent.

[0034] The materials used to create the clay body are listed below. (soil) • Clay: A mixture of kaolin clay (manufactured by Yamasu Co., Ltd.) and sand: silica sand No. 4 and silica sand No. 5 (manufactured by Yamasu Co., Ltd.) Mixing ratio: clay:silica sand No. 4:silica sand No. 5 = mass ratio 2:1:1 (PVA resin) • PVA-based resin Gosenol (registered trademark: same applies hereafter) GH-17R (partially saponified product: degree of saponification 86.5 mol%~89.0 mol%:: manufactured by Mitsubishi Chemical Corporation) • PVA-based resin Gosenor N-300 (fully saponified: degree of saponification > 98 mol%: manufactured by Mitsubishi Chemical Corporation) • PVA-based resin Gosenex T-350 (carboxyl group modified product: manufactured by Mitsubishi Chemical Corporation) • PVA-based resin Gosenex Z-320 (acetoacetyl group modified product, manufactured by Mitsubishi Chemical Corporation, crosslinkable) (Antifoaming agent) • Concrete defoaming agent AFK-2 (manufactured by Takemoto Oil Co., Ltd.) (Crosslinking agent) • Crosslinking agent: Safelink SPM-01 (manufactured by Mitsubishi Chemical Corporation) (water) Tap water

[0035] <Examples 1-3> The PVA resins listed in Table 1 were pre-dissolved in water to prepare PVA resin aqueous solutions. The concentration of the PVA resin aqueous solution varied depending on the type of PVA resin, but was set in the range of 10% to 20% by mass. 12.2 kg of soil and an aqueous solution of PVA resin (prepared by dissolving the PVA resin listed in Table 1 in water) were added in an amount equal to 1% by mass of solids relative to the soil. The mixture was then kneaded at low speed (154 rpm (revolutions / minute)) for 5 minutes using a mixer (Aikousha Co., Ltd., 30L mixer: with deaeration device), and then kneaded at medium speed (234 rpm) for 10 minutes to obtain the mixture. (Step 1)

[0036] <Examples 4-7> PVA resin aqueous solutions were prepared by pre-dissolving the PVA resins listed in Table 1 in water. 3 kg of soil and an aqueous solution of PVA resin (prepared by dissolving the PVA resin listed in Table 1 in water) were added to the soil in an amount equal to 1% by mass of solids. The mixture was then kneaded using a mixer (Aikousha Co., Ltd., 20L mixer) under the same conditions as in Example 1 to obtain a mixture. (Step 1)

[0037] The mixtures used in Examples 1 to 7, obtained above, were poured into a flat mold with internal dimensions of 300 mm x 300 mm x 60 mm. The mold was made of wood and coated with silicone grease on the inside. The mixture was added in two stages. First, half of the mixture was added as a first layer, and then a vibrator was used for one minute to remove any voids. After that, the remaining half was added as the second layer, and the vibrator was used for one minute in the same manner. The material was allowed to air dry for one week, and its appearance was observed while still in the mold. After another week of air drying, the molded soil body was obtained. (Step 2)

[0038] In Example 2, an additional 3g of defoaming agent was added during the preparation of the mixture, and a soil molded body was obtained in the same manner as in Example 1. In Example 3, the mixture was kneaded while degassing to -0.1 MPa using the degassing device of the above-mentioned mixer (manufactured by Aikousha, 30L mixer with degassing device).

[0039] <Comparative Example 1> A soil molded body was obtained in the same manner as in Example 1, except that the same type and amount of soil as in Example 1 was used, PVA was not added, and only 4.9 kg of water was added. In Table 1 below, "-" indicates that the ingredient is not included.

[0040] [Table 1]

[0041] (Evaluation of soil-formed bodies) The following items were evaluated, and the results are shown in Table 2 below.

[0042] 1. Appearance (cracking due to volumetric shrinkage and deformation of the soil molded body) The appearance of the plate-shaped soil molded bodies was visually observed and evaluated according to the following criteria. A: No cracks due to volume shrinkage or deformation of the soil molded body were observed after one week or two weeks. B: After one week, no cracks or deformation due to volume shrinkage were observed, but after two weeks, cracks or deformation due to volume shrinkage were observed. C: At both 1 week and 2 weeks post-processing, cracking and deformation due to volume shrinkage were observed.

[0043] 2. Compressive strength The mixture obtained in step 1 was poured into molds of the following sizes, air-dried for one week to obtain a soil molded body, and its compressive strength was measured under the following conditions. Formwork size: Cylindrical formwork measuring φ20mm x height 40mm The cylindrical clay body was air-dried for one week. The parts of both ends that contact the formwork were capped with epoxy resin. The obtained cylindrical test specimens were subjected to compression strength testing using a compression strength tester of grade 1 or higher, in accordance with the provisions of JIS B7721:2012.

[0044] 3. Bending strength Using flat, molded clay plates (naturally dried for one week) whose external appearance had been observed, the bending strength was measured in accordance with JIS R5201:2015.

[0045] 4. Water resistance (appearance and water absorption rate) Flat, slab-shaped clay bodies (naturally dried for one week) that had been observed for their appearance were cut into 40mm x 40mm x 20mm pieces to be used as test specimens for evaluating water resistance. The test specimens of the clay bodies of the above size were immersed in tap water at 25°C, and after 60 minutes, the water resistance was evaluated based on appearance and water absorption rate according to the following criteria.

[0046] (Evaluation of appearance) Test specimens of the above-mentioned size of the molded clay body were immersed in tap water at 25°C, and their appearance was observed after 60 minutes to evaluate whether or not the shape had collapsed after immersion in tap water.

[0047] (Measurement of water absorption rate) After immersing a clay molded test piece cut to a size of 40mm x 40mm x 20mm in tap water at 25°C for 60 minutes, After removing the test specimen, any water droplets adhering to it were wiped off with a damp cloth, and the mass of the clay molded body after water immersion was measured. Here, the amount of water absorbed was as follows: Water absorption amount = (Mass of the soil molded body immediately after water immersion) - (Mass of the soil molded body before water immersion) The water absorption rate was calculated using the following formula (Equation 1). (Formula 1) Water absorption rate (%)= [(Amount of water absorbed) / Mass of the clay body before soaking in water] × 100 The lower the water absorption rate, the better the water resistance is considered to be.

[0048] [Evaluation Criteria] A: No disintegration of the test specimen due to water absorption was observed, and the water absorption rate was less than 7.5%. B: No disintegration of the test specimen due to water absorption was observed, and the water absorption rate was between 7.5% and less than 11%. C: No disintegration of the test specimen due to water absorption was observed, and the water absorption rate was 11% or higher. D: Disintegration of the test specimen was observed due to water absorption. In the case of grade D, the water absorption rate was not measured because the shape of the test specimen collapsed.

[0049] 5.Water resistance (mass retention rate) Flat, molded clay slabs (naturally dried for one week) that had been observed externally were immersed in 25°C tap water for 60 minutes. The clay molded bodies were allowed to air dry for two weeks after immersion, and their mass was measured. The mass before and after immersion was compared, and the mass retention rate before and after immersion was measured using the following formula (Equation 2). (Formula 2) Mass retention rate (%)= [(Mass of the test specimen after water immersion and 2 weeks of natural drying) / (Mass of the clay molded body before water immersion)] × 100 A higher mass retention rate indicates superior water resistance.

[0050] [Table 2]

[0051] The evaluation results showed that the interior and exterior building materials of Examples 1 to 7, obtained by the manufacturing method of the interior and exterior building materials of this disclosure, all had high compressive strength and good water resistance. In particular, a comparison of Example 1 with Examples 2 and 3 shows that using an antifoaming agent during kneading and performing degassing using a mixer equipped with a degassing device results in better volume shrinkage and suppression of deformation. Furthermore, a comparison between Example 6 and Example 7 shows that adding a crosslinking agent results in improved compressive strength and flexural strength.

Claims

1. A process of kneading soil, vinyl alcohol-based resin in an amount of 0.1% to 10% by mass relative to the total mass of the soil, and water to obtain a mixture, The process includes molding and solidifying the resulting mixture to obtain a clay molded body. A method for manufacturing interior and exterior building materials.

2. The method for producing interior and exterior building materials according to claim 1, wherein the mixture further comprises an antifoaming agent.

3. The method for manufacturing interior and exterior building materials according to claim 1, wherein the kneading in the step of obtaining the mixture is performed by a kneader equipped with a degassing device.

4. A soil molded body containing soil and vinyl alcohol-based resin in an amount of 0.1% to 10% by mass relative to the total mass of the soil. The compressive strength measured under the following conditions was 1 N / mm². ２ Furthermore, the bending strength measured in accordance with JIS R5201:2015 was 0.8 N / mm². ２ That concludes the description of interior and exterior building materials. (Compressive strength measurement conditions) Using a cylindrical mold measuring φ20 mm x height 40 mm, a cylindrical clay body is obtained. The parts of both ends that come into contact with the formwork are capped with epoxy resin. The obtained cylindrical test specimens are subjected to a compression strength tester of grade 1 or higher in accordance with the provisions of JIS B7721:2012 to measure their compressive strength.

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