JP2017190645A

JP2017190645A - Clay roof tile

Info

Publication number: JP2017190645A
Application number: JP2016082213A
Authority: JP
Inventors: 一史井野; Kazufumi Ino
Original assignee: Ino Kawara Kogyo Co Ltd; SANSYU FRIT KK
Current assignee: Ino Kawara Kogyo Co Ltd; SANSYU FRIT KK
Priority date: 2016-04-15
Filing date: 2016-04-15
Publication date: 2017-10-19

Abstract

PROBLEM TO BE SOLVED: To provide a clay roof tile that has high bending fracture strength and low mass.SOLUTION: A clay roof tile 10 comprises: a basis material layer 20 formed of clay; a first glaze layer 30, which is disposed on a rear face of the basis material layer 20; and a second glaze layer 40, which is disposed on a front face of the basis material layer 20. The glaze constituting the first glaze layer 30 preferably contains one or two or more materials selected from a group formed of α-alumina (AlO), zircon (ZrOSiO), spodumene (LiOAlO4SiO), petalite (LiOAlO8SiO), and cordierite (2MgO2AlO5SiO).SELECTED DRAWING: Figure 1

Description

本発明は、粘土瓦に関する。 The present invention relates to a clay roof tile.

建築物の屋根瓦として用いられる粘土瓦は、所定の形状に成形された粘土を焼成して作製される。粘土瓦は、保形性や強度面から、その厚みは１４ｍｍ前後あるいはそれ以上である。このため、粘土瓦は、重く、輸送や屋根葺き作業上の取扱いが容易でない。また、屋根に重い粘土瓦を配置すると、建築物の強度を大きくする必要があり、建築コストが高くなる原因にもなる。これらのことから、軽量な粘土瓦が求められている。 A clay tile used as a roof tile of a building is produced by firing clay molded into a predetermined shape. The clay roof has a thickness of about 14 mm or more in terms of shape retention and strength. For this reason, clay tiles are heavy and are not easy to handle during transportation and roofing work. In addition, if heavy clay tiles are arranged on the roof, it is necessary to increase the strength of the building, which also increases the construction cost. For these reasons, lightweight clay roof tiles are required.

瓦の軽量化を実現するために、各種の瓦が提案されている。特許文献１には、粘土素材におが屑を混合した瓦粘土により瓦を成形し、これを焼成して瓦粘土中のおが屑を焼却せしめて、微少な空洞を形成して多孔質とし、従来の鉱物質のみの瓦粘土で形成された瓦より軽量化した粘土瓦が開示されている。 Various tiles have been proposed to reduce the weight of the tiles. In Patent Document 1, a tile is formed from a clay clay mixed with sawdust in a clay material, and this is fired to burn the sawdust in the tile clay to form a microscopic cavity, making it a porous material. A clay roof tile is disclosed which is lighter than a roof tile made from quality tile clay.

特開２００２−９７７４７号公報JP 2002-97747 A

しかしながら、特許文献１の粘土瓦は、空洞を形成することで軽量化しているため、曲げ破壊強度が小さくなるという問題がある。粘土瓦の曲げ破壊強度が小さくなると、飛来物が当たった場合などに割れる虞がある。このため、粘土瓦が所定の曲げ破壊強度を有することも求められている。 However, since the clay roof tile of Patent Document 1 is lightened by forming a cavity, there is a problem that bending fracture strength is reduced. If the bending fracture strength of the clay roof becomes small, there is a risk of cracking when a flying object hits it. For this reason, it is also required that clay roof tiles have a predetermined bending fracture strength.

本発明は、このような実情に鑑みてなされたものであり、曲げ破壊強度が大きく、質量の小さい粘土瓦を提供することを目的とする。 The present invention has been made in view of such circumstances, and an object thereof is to provide a clay roof tile having a high bending fracture strength and a small mass.

上記目的を達成するため、本発明に係る粘土瓦は、
粘土から構成される素地層と、前記素地層の裏面に配置された第１の釉薬層と、前記素地層の表面に配置された第２の釉薬層と、
を備えることを特徴とする。 In order to achieve the above object, the clay roof according to the present invention is:
A base layer composed of clay, a first glaze layer disposed on the back surface of the base layer, a second glaze layer disposed on the surface of the base layer,
It is characterized by providing.

粘土瓦が上記構成を備えることで、釉薬層を備えない粘土瓦や表面のみに釉薬層を備える粘土瓦より大きい曲げ破壊強度を有する。上記構成を備える粘土瓦は大きい曲げ破壊強度を有するため、必要な曲げ破壊強度を保ちつつ、粘土瓦の厚みを小さくできる。これにより、粘土瓦に必要な曲げ破壊強度を保ちつつ、粘土瓦の質量を小さくできる。 When the clay roof has the above-described configuration, it has a bending fracture strength higher than that of the clay roof without the glaze layer or the clay roof with the glaze layer only on the surface. Since the clay roof having the above configuration has a high bending fracture strength, the thickness of the clay roof can be reduced while maintaining the required bending fracture strength. Thereby, the mass of a clay roof tile can be made small, maintaining the bending fracture strength required for a clay roof tile.

前記第１の釉薬層を構成する釉薬は、α−アルミナ（Ａｌ_２Ｏ_３）、ジルコン（ＺｒＯ_２ＳｉＯ_２）、スポジューメン（Ｌｉ_２ＯＡｌ_２Ｏ_３４ＳｉＯ_２）、ペタライト（Ｌｉ_２ＯＡｌ_２Ｏ_３８ＳｉＯ_２）、コージライト（２ＭｇＯ２Ａｌ_２Ｏ_３５ＳｉＯ_２）からなる群から選択される１または２以上の材料を含むとよい。
前記釉薬層を構成する釉薬が、α−アルミナ、ジルコンを含むことで、前記釉薬層の密度が大きくなり、粘土瓦の曲げ破壊強度を大きくすることに寄与すると考えられる。また、前記釉薬層を構成する釉薬が、スポジューメン、ペタライト、コージライトを含むことで、前記釉薬層の線熱膨張係数が、前記素地層の線熱膨張係数より小さくなり、粘土瓦を焼成した後冷却すると、釉薬層にコンプレッション（圧縮応力）が加わる。釉薬層にコンプレッションが加わることで粘土瓦の曲げ破壊強度を大きくすることに寄与すると考えられる。粘土瓦が大きい曲げ破壊強度を有することで、必要な曲げ破壊強度を保ちつつ、粘土瓦の厚みを小さくできる。これにより、粘土瓦に必要な曲げ破壊強度を保ちつつ、粘土瓦の質量を小さくできる。 The glaze constituting the first glaze layer is α-alumina (Al ₂ O ₃ ), zircon (ZrO ₂ SiO ₂ ), spodumene (Li ₂ OAl ₂ O ₃ 4SiO ₂ ), petalite (Li ₂ OAl ₂ O _3). 8SiO ₂ ), cordierite (2MgO ₂ Al ₂ O ₃ 5SiO ₂ ), or one or more materials selected from the group consisting of cordierite.
When the glaze which comprises the said glaze layer contains (alpha) -alumina and zircon, it is thought that the density of the said glaze layer becomes large and contributes to increasing the bending fracture strength of a clay roof tile. In addition, the glaze composing the glaze layer contains spodumene, petalite, cordierite, the linear thermal expansion coefficient of the glaze layer is smaller than the linear thermal expansion coefficient of the base layer, after the clay tile is fired When cooled, compression (compressive stress) is applied to the glaze layer. It is thought that the compression added to the glaze layer contributes to increasing the bending fracture strength of clay roof tiles. Since the clay roof has a high bending fracture strength, the thickness of the clay roof can be reduced while maintaining the required bending fracture strength. Thereby, the mass of a clay roof tile can be made small, maintaining the bending fracture strength required for a clay roof tile.

前記第１の釉薬層を構成する釉薬は、４質量％以上５質量％以下のコージライト、２質量％以上３質量％以下のα−アルミナ、または１質量％以上２質量％以下のジルコンを含み、
ゼーゲル式にて、
Ｎａ_２Ｏが０．０１モル、Ｋ_２Ｏが０．０１モル、ＭｇＯが０．０５モル、ＣａＯが０．１８モル、ＭｎＯが０．７６モル、
Ａｌ_２Ｏ３が０．１６モル、Ｆｅ_２Ｏ_３が０．０３モル、Ｂ_２Ｏ_３が０．０８モル、
ＳｉＯ_２が１．３３モル、ＴｉＯ_２が０．２２モル、ＺｒＯ_２が０．３１モル、
として表される組成であるとよい。
このようにすることで、粘土瓦の曲げ破壊強度をより大きくすることができ、粘土瓦に必要な曲げ破壊強度を保ちつつ、粘土瓦の質量を小さくできる。また、前記第２の釉薬層に結晶系銀色釉薬を用いた場合、見付け部分（表面と裏面と釉薬層の重なり部分）の第２の釉薬層の色調と第１の釉薬層の色調との違いが目立たなくなる。 The glaze that constitutes the first glaze layer contains 4% by mass to 5% by mass cordierite, 2% by mass to 3% by mass α-alumina, or 1% by mass to 2% by mass zircon. ,
In the Segel formula,
Na ₂ O 0.01 mol, K ₂ O 0.01 mol, MgO 0.05 mol, CaO 0.18 mol, MnO 0.76 mol,
Al ₂ O 3 is 0.16 mol, Fe ₂ O ₃ is 0.03 mol, B ₂ O ₃ is 0.08 mol,
SiO ₂ is 1.33 mol, TiO ₂ is 0.22 mol, ZrO ₂ is 0.31 mol,
It is good that it is expressed as
By doing in this way, the bending fracture strength of the clay roof tile can be further increased, and the mass of the clay roof tile can be reduced while maintaining the bending fracture strength required for the clay roof tile. Further, when a crystalline silver glaze is used for the second glaze layer, the difference between the color tone of the second glaze layer and the color tone of the first glaze layer in the found portion (the overlapping portion of the front surface, back surface and glaze layer) Disappears.

前記第１の釉薬層を構成する釉薬は、２質量％以上６質量％以下のコージライト、または２質量％のペタライト、を含み、
ゼーゲル式にて、
Ｎａ_２Ｏが０．０１モル、Ｋ_２Ｏが０．０１モル、ＬｉＯ_２が０．２１モル、ＭｇＯが０．６７モル、ＣａＯが０．０２モル、ＭｎＯが０．０８モル、
Ａｌ_２Ｏ_３が０．６７モル、Ｆｅ_２Ｏ_３が０．０５モル、
ＳｉＯ_２が３．０８モル、ＴｉＯ_２が１．０１モル、ＺｒＯ_２が０．６３モル、
として表される組成であるとよい。
このようにすることで、粘土瓦の曲げ破壊強度をより大きくすることができ、粘土瓦に必要な曲げ破壊強度を保ちつつ、粘土瓦の質量を小さくできる。また、前記第２の釉薬層にいぶし系銀色釉薬を用いた場合、見付け部分の第２の釉薬層の色調と第１の釉薬層の色調との違いが目立たなくなる。 The glaze constituting the first glaze layer contains 2% by mass to 6% by mass of cordierite, or 2% by mass of petalite,
In the Segel formula,
Na ₂ O 0.01 mol, K ₂ O 0.01 mol, LiO ₂ 0.21 mol, MgO 0.67 mol, CaO 0.02 mol, MnO 0.08 mol,
Al ₂ O ₃ is 0.67 mol, Fe ₂ O ₃ is 0.05 mol,
SiO ₂ is 3.08 mol, TiO ₂ is 1.01 mol, ZrO ₂ is 0.63 moles,
It is good that it is expressed as
By doing in this way, the bending fracture strength of the clay roof tile can be further increased, and the mass of the clay roof tile can be reduced while maintaining the bending fracture strength required for the clay roof tile. In addition, when the silver glaze is used for the second glaze layer, the difference between the color tone of the second glaze layer and the color tone of the first glaze layer at the found portion is not noticeable.

前記第１の釉薬層を構成する釉薬は、４質量％以上６質量％以下のコージライトを含み、
ゼーゲル式にて、
Ｎａ_２Ｏが０．０１モル、Ｋ_２Ｏが０．０１モル、ＭｇＯが０．０２モル、ＣａＯが０．０７モル、ＭｎＯが０．８０モル、ＢａＯが０．０９モル、
Ａｌ_２Ｏ_３が０．２７モル、Ｆｅ_２Ｏ_３が０．０２モル、
ＳｉＯ_２が１．６６モル、ＴｉＯ_２が０．１９モル、ＺｒＯ_２が０．１３、Ｂ_２Ｏ_３が０．０４モル、
として表される組成であるとよい。
このようにすることで、粘土瓦の曲げ破壊強度をより大きくすることができ、粘土瓦に必要な曲げ破壊強度を保ちつつ、粘土瓦の質量を小さくできる。また、前記第２の釉薬層に半光沢黒色（ブラックマット）釉薬を用いた場合、見付け部分の第２の釉薬層の色調と第１の釉薬層の色調との違いが目立たなくなる。 The glaze constituting the first glaze layer contains 4% by mass or more and 6% by mass or less cordierite,
In the Segel formula,
Na ₂ O 0.01 mol, K ₂ O 0.01 mol, MgO 0.02 mol, CaO 0.07 mol, MnO 0.80 mol, BaO 0.09 mol,
Al ₂ O ₃ is 0.27 mol, Fe ₂ O ₃ is 0.02 mol,
SiO ₂ is 1.66 mol, TiO ₂ is 0.19 mol, ZrO ₂ is _0.13, B 2 _{O 3} is 0.04 mol,
It is good that it is expressed as
By doing in this way, the bending fracture strength of the clay roof tile can be further increased, and the mass of the clay roof tile can be reduced while maintaining the bending fracture strength required for the clay roof tile. Further, when a semi-glossy black (black matte) glaze is used for the second glaze layer, the difference between the color tone of the second glaze layer in the found portion and the color tone of the first glaze layer becomes inconspicuous.

前記第１の釉薬層を構成する釉薬は、
ゼーゲル式にて、
Ｎａ_２Ｏが０モル超０．０３モル以下、Ｋ_２Ｏが０モル超０．０３モル以下、ＣａＯが０．０２モル、Ｌｉ_２Ｏが０．０９モル以上０．９９モル以下、
Ａｌ_２Ｏ_３が１．００モル以上２．００モル以下、
ＳｉＯ_２が６．３１モル以上８．３１モル以下、
として表される組成であるとよい。
また、前記第１の釉薬層を構成する釉薬は、
１質量％以上７質量％以下のα−アルミナ、１質量％以上２質量％以下のジルコン、１質量％以上１００質量％未満のペタライト、または１質量％以上２０質量％以下のスポジューメンを含むとよい。
このようにすることで、粘土瓦の曲げ破壊強度をより大きくすることができ、粘土瓦に必要な曲げ破壊強度を保ちつつ、粘土瓦の質量を小さくできる。また、前記第２の釉薬層にハイシルバー釉薬を用いた場合、見付け部分の第２の釉薬層の色調と第１の釉薬層の色調との違いが目立たなくなる。 The glaze constituting the first glaze layer is
In the Segel formula,
Na ₂ O more than 0 mol 0.03 mol or less, K ₂ O more than 0 mol 0.03 mol or less, CaO 0.02 mol, Li ₂ O 0.09 mol or more and 0.99 mol or less,
Al ₂ O ₃ is 1.00 mol or more and 2.00 mol or less,
SiO ₂ is 6.31 mol or more and 8.31 mol or less,
It is good that it is expressed as
Moreover, the glaze which comprises the said 1st glaze layer is
It may contain 1% by mass or more and 7% by mass or less α-alumina, 1% by mass or more and 2% by mass or less zircon, 1% by mass or more and less than 100% by mass petalite, or 1% by mass or more and less than 20% by mass spodomen. .
By doing in this way, the bending fracture strength of the clay roof tile can be further increased, and the mass of the clay roof tile can be reduced while maintaining the bending fracture strength required for the clay roof tile. Further, when a high silver glaze is used for the second glaze layer, the difference between the color tone of the second glaze layer at the found portion and the color tone of the first glaze layer becomes inconspicuous.

本発明によれば、粘土瓦が、釉薬層を備えない粘土瓦や表面のみに釉薬層を備える粘土瓦より大きい曲げ破壊強度を有する。このため、必要な曲げ破壊強度を保ちつつ、粘土瓦の厚みを小さくできる。これにより、粘土瓦に必要な曲げ破壊強度を保ちつつ、粘土瓦の質量を小さくでき、曲げ破壊強度が大きく、質量の小さい粘土瓦を提供することが可能となる。 According to the present invention, a clay roof tile has a bending fracture strength greater than that of a clay roof tile without a glaze layer or a clay roof tile with a glaze layer only on the surface. For this reason, the thickness of the clay roof tile can be reduced while maintaining the required bending fracture strength. Thereby, it is possible to reduce the mass of the clay roof tile while maintaining the bending fracture strength necessary for the clay roof tile, and to provide a clay roof tile having a high bending fracture strength and a small mass.

第１〜４の実施の形態に係る粘土瓦を示す断面図である。It is sectional drawing which shows the clay roof tile which concerns on 1st-4th embodiment. （Ａ）は、粘土瓦の曲げ破壊強度の測定方法を示す上面図であり、（Ｂ）は、粘土瓦の曲げ破壊強度の測定方法を示す側面図である。(A) is a top view which shows the measuring method of the bending fracture strength of a clay roof, (B) is a side view which shows the measuring method of the bending fracture strength of a clay roof.

以下、本発明を実施するための形態に係る粘土瓦を図面を参照しながら詳細に説明する。 Hereinafter, a clay roof according to an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

（第１の実施の形態）
第１の実施の形態に係る粘土瓦１０は、図１に示すように、素地層２０と、素地層２０の裏面に配置された第１の釉薬層３０と、素地層２０の表面に配置された第２の釉薬層４０と、を備える。なお表面は、屋根に配置したとき外観に表れる面である。粘土瓦１０は、後述する第１の釉薬層３０を構成する粘土瓦用釉薬Ａと第２の釉薬層４０を構成する粘土瓦用釉薬Ｒとを素地層２０にそれぞれ施釉した後、１０００℃〜１２００℃で酸化焼成されたものであり、一般の粘土瓦と同様の色彩、光沢を備えつつ、大きい曲げ破壊強度を有する。粘土瓦１０が大きい曲げ破壊強度を有することで、瓦に必要な曲げ破壊強度を保ちつつ、粘土瓦１０の厚みを小さくできる。これにより、粘土瓦１０の質量を小さくできる。 (First embodiment)
As shown in FIG. 1, the clay roof tile 10 according to the first embodiment is disposed on the surface of the base layer 20, the first glaze layer 30 disposed on the back surface of the base layer 20, and the base layer 20. And a second glaze layer 40. The surface is a surface that appears on the exterior when placed on the roof. The clay roof tile 10 is applied with the glaze A for clay roof tiles constituting the first glaze layer 30 and the glaze R for clay roof tiles constituting the second glaze layer 40 on the base layer 20, respectively. It is oxidized and fired at 1200 ° C., and has a high bending fracture strength while having the same color and gloss as ordinary clay roof tiles. Since the clay roof tile 10 has a high bending fracture strength, the thickness of the clay roof tile 10 can be reduced while maintaining the bending fracture strength required for the roof tile. Thereby, the mass of the clay roof tile 10 can be reduced.

素地層２０は、粘土を主原料とする原料を混練、成形および焼成したものから構成される。素地層２０の線熱膨張係数は、例えば６．８×１０^−６／℃である。 The base layer 20 is composed of a material obtained by kneading, molding and firing a raw material mainly composed of clay. The linear thermal expansion coefficient of the base layer 20 is, for example, 6.8 × 10 ⁻⁶ / ° C.

第１の釉薬層３０は、粘土瓦用釉薬Ａから構成される。粘土瓦用釉薬Ａは、４質量％以上５質量％以下のコージライト（２ＭｇＯ２Ａｌ_２Ｏ_３５ＳｉＯ_２）、２質量％以上３質量％以下のα−アルミナ（Ａｌ_２Ｏ_３）、または１質量％以上２質量％以下のジルコン（ＺｒＯ_２ＳｉＯ_２）を含み、
ゼーゲル式にて、
Ｎａ_２Ｏが０．０１モル、Ｋ_２Ｏが０．０１モル、ＭｇＯが０．０５モル、ＣａＯが０．１８モル、ＭｎＯが０．７６モル、
Ａｌ_２Ｏ_３が０．１６モル、Ｆｅ_２Ｏ_３が０．０３モル、Ｂ_２Ｏ_３が０．０８モル、
ＳｉＯ_２が１．３３モル、ＴｉＯ_２が０．２２モル、ＺｒＯ_２が０．３１モル、
として表される組成から構成される。 The first glaze layer 30 is composed of clay tile glaze A. The glaze A for clay roof tiles is 4% to 5% by weight cordierite (2MgO2Al ₂ O ₃ 5SiO ₂ ), 2% to 3% by weight α-alumina (Al ₂ O ₃ ), or 1% by weight. Containing ₂ % by mass or less of zircon (ZrO ₂ SiO ₂ ),
In the Segel formula,
Na ₂ O 0.01 mol, K ₂ O 0.01 mol, MgO 0.05 mol, CaO 0.18 mol, MnO 0.76 mol,
Al ₂ O ₃ is 0.16 mol, Fe ₂ O ₃ is 0.03 mol, B ₂ O ₃ is 0.08 mol,
SiO ₂ is 1.33 mol, TiO ₂ is 0.22 mol, ZrO ₂ is 0.31 mol,
It is comprised from the composition represented as.

コージライトの熱線膨張係数は、２．６〜２．８×１０^−６／℃、融点は１４５０℃である。粘土瓦用釉薬Ａが、コージライトを４質量％以上含むことで、第１の釉薬層３０の線熱膨張係数は、素地層２０の線熱膨張係数より一定以上小さくなる。また、コージライトの融点は、粘土瓦１０の焼成温度より高いので、焼成した際、コージライトが溶融せず固体のまま第１の釉薬層３０に残る。このことも、第１の釉薬層３０の線熱膨張係数を小さくすることに寄与すると考えられる。この結果、粘土瓦１０が焼成した後冷却されると、素地層２０と第１の釉薬層３０との線熱膨張係数の差により、第１の釉薬層３０にコンプレッション（圧縮応力）が加わる。これにより、粘土瓦１０の曲げ破壊強度を高めることができると考えられる。
また、粘土瓦用釉薬Ａが、コージライトを５質量％以下含むことで、見付け部分（表面と裏面の重なり部分）の第２の釉薬層４０の色調と第１の釉薬層３０の色調との違いが目立たなくなる。なお、第２の釉薬層４０の詳細については後述する。 Cordierite has a coefficient of thermal expansion of 2.6 to 2.8 × 10 ⁻⁶ / ° C. and a melting point of 1450 ° C. When the glaze A for clay roof contains 4 mass% or more of cordierite, the linear thermal expansion coefficient of the first glaze layer 30 becomes smaller than the linear thermal expansion coefficient of the base layer 20 by a certain amount or more. Moreover, since the melting point of cordierite is higher than the firing temperature of the clay roof tile 10, the cordierite does not melt and remains in the first glaze layer 30 as a solid when fired. This is also considered to contribute to reducing the linear thermal expansion coefficient of the first glaze layer 30. As a result, when the clay roof tile 10 is fired and then cooled, compression (compression stress) is applied to the first glaze layer 30 due to the difference in linear thermal expansion coefficient between the base layer 20 and the first glaze layer 30. Thereby, it is thought that the bending fracture strength of the clay roof tile 10 can be increased.
Moreover, the glaze A for clay tiles contains 5 mass% or less of cordierite, so that the color tone of the second glaze layer 40 and the color tone of the first glaze layer 30 in the found portion (the overlapping portion of the front surface and the back surface) The difference is less noticeable. The details of the second glaze layer 40 will be described later.

また、α−アルミナの密度は、３．９５ｇ／ｃｍ^３、融点は２０７２℃である。ジルコンの密度は、４．７ｇ／ｃｍ^３、融点は２５５０℃である。粘土瓦用釉薬Ａがα−アルミナを２質量％以上、またはジルコンを１質量％以上含むことで、第１の釉薬層３０の密度が大きくなり、粘土瓦１０の曲げ破壊強度を高めることに寄与すると考えられる。また、α−アルミナ、ジルコンの融点は、粘土瓦１０の焼成温度より高いので、焼成した際、これらの物質が溶融せず固体のまま第１の釉薬層３０に残る。このことも、粘土瓦１０の曲げ破壊強度を高めることに寄与すると考えられる。
また、粘土瓦用釉薬Ａが、α−アルミナを３質量％以下、またはジルコンを１質量％以下含むことで、見付け部分の第２の釉薬層４０の色調と第１の釉薬層３０の色調との違いが目立たなくなる。 The density of α-alumina is 3.95 g / cm ³ and the melting point is 2072 ° C. The density of zircon is 4.7 g / cm ³ and the melting point is 2550 ° C. When the glaze A for clay roof contains 2% by mass or more of α-alumina or 1% by mass or more of zircon, the density of the first glaze layer 30 increases and contributes to increasing the bending fracture strength of the clay roof 10. I think that. Moreover, since melting | fusing point of (alpha) -alumina and zircon is higher than the calcination temperature of the clay roof tile 10, when baked, these substances do not melt and remain in the first glaze layer 30 as a solid. This is also considered to contribute to increasing the bending fracture strength of the clay roof tile 10.
Further, the glaze A for clay roof contains 3% by mass or less of α-alumina or 1% by mass or less of zircon, so that the color tone of the second glaze layer 40 and the color tone of the first glaze layer 30 in the found portion are The difference becomes inconspicuous.

ゼーゲル式で表されたＮａ_２Ｏ、Ｋ_２Ｏ、Ｌｉ_２Ｏ、ＭｇＯ、ＣａＯ、ＭｎＯは、粘土瓦用釉薬Ａの溶ける温度を調整するために加えられるものである。これらは、粘土瓦用釉薬Ａの中では、電子供与性（電子を放出しやすい性質）の塩基性成分として振るまい、多く加えると溶融温度が低下する。 Na ₂ O, K ₂ O, Li ₂ O, MgO, CaO, and MnO expressed by the Seegel formula are added to adjust the melting temperature of the glaze A for clay roof tiles. In the glaze A for clay roof tiles, these do not behave as electron-donating (a property that easily emits electrons) basic components, and if added in large quantities, the melting temperature decreases.

ゼーゲル式で表されたＡｌ_２Ｏ_３、ＦｅＯ_３、Ｂ_２Ｏ_３は、粘土瓦用釉薬Ａ中で中性成分として振るまい、粘土瓦用釉薬Ａが溶ける温度には影響しない。これらは、粘土瓦用釉薬Ａが結晶化するのを防ぎ釉薬の清澄性を促進し、粘土瓦用釉薬Ａに適度な粘りを持たせ厚みを均一にする働きがある。 Al ₂ O ₃ , FeO ₃ , and B ₂ O ₃ represented by the Seegel formula do not affect the temperature at which the glaze A for clay roofing melts and does not act as a neutral component in the glaze A for clay roofing. These prevent the glaze A for clay roof tiles from crystallizing, promote the clarity of the glaze, and have the clay A for clay roof tiles having an appropriate viscosity to make the thickness uniform.

ゼーゲル式で表されたＳｉＯ_２、ＴｉＯ_２、ＺｒＯ_２は、粘土瓦用釉薬Ａ中で電子受容性（電子を引きつける性質）を持つ酸として振るまい、粘土瓦用釉薬Ａの溶融温度を上昇させる働きがある。これらを加え過ぎると、釉薬が溶ける温度が上昇し、仕上がりが不透明になる傾向がある。逆に少なすぎると粘度が小さくなり、脆くなる。 SiO ₂ , TiO ₂ , and ZrO ₂ represented by the Seegel formula behave as an acid having an electron accepting property (a property of attracting electrons) in the glaze A for clay roof tiles, and increase the melting temperature of the glaze A for clay roof tiles. There is work. If these are added too much, the temperature at which the glaze melts rises and the finish tends to become opaque. On the other hand, if the amount is too small, the viscosity becomes small and the material becomes brittle.

第２の釉薬層４０は、結晶系銀色釉薬である粘土瓦用釉薬Ｒから構成される。なお、結晶系銀色釉薬層を配置した粘土瓦は、「新銀」として井野瓦工業株式会社で販売されているものである。 The second glaze layer 40 is composed of a clay tile glaze R, which is a crystalline silver glaze. Note that the clay roof tiles on which the crystalline silver glaze layer is arranged are sold as “Shin Silver” by Ino Kawara Kogyo Co., Ltd.

粘土瓦用釉薬Ｒは、ゼーゲル式にて、
Ｎａ_２Ｏが０．０２モル以下、Ｋ_２Ｏが０．０２モル以下、Ｌｉ_２Ｏが０．１０〜０．４０モル、ＣａＯが０．０１〜０．３０モル、ＭｇＯが０．０１〜０．２０モル、ＭｎＯが０．５０〜０９０モル、
Ａｌ_２Ｏ_３が０．１０〜０．８０モル、Ｆｅ_２Ｏ_３が０．０１〜０．１０モル、Ｂ_２Ｏ_３が０．０１〜０．１０モル、
ＳｉＯ_２が１．００〜４．００モル、ＴｉＯ_２が０．０５〜２．００モル、ＺｒＯ_２が０．２０〜０．４０モル、
として表される組成から構成される。 The glaze R for clay roof tiles is the Zegel formula,
Na ₂ O is 0.02 mol or less, K ₂ O is 0.02 mol or less, Li ₂ O is 0.10 to 0.40 mol, CaO is 0.01 to 0.30 mol, MgO is 0.01 to 0.20 mol, MnO 0.50-090 mol,
Al ₂ O ₃ is 0.10 to 0.80 mol, Fe ₂ O ₃ is 0.01 to 0.10 mol, B ₂ O ₃ is 0.01 to 0.10 mol,
SiO ₂ is 1.00 to 4.00 mol, TiO ₂ is from 0.05 to 2.00 mol, ZrO ₂ is 0.20 to 0.40 mol,
It is comprised from the composition represented as.

粘土瓦用釉薬Ｒのゼーゲル式による作用効果は、上述した粘土瓦用釉薬Ａのゼーゲル式による作用効果と同様である。 The effect of the clay tile glaze R according to the Zegel formula is the same as the effect of the clay tile glaze A according to the Zegel formula described above.

つぎに、粘土瓦１０の製造方法について説明する。 Next, a method for manufacturing the clay roof tile 10 will be described.

粘土瓦１０の製造方法は、粘土瓦用釉薬Ａおよび粘土瓦用釉薬Ｒの調製工程と、素地層２０の成形工程と、粘土瓦用釉薬Ａおよび粘土瓦用釉薬Ｒを素地層２０に施釉する施釉工程と、粘土瓦１０を焼成する焼成工程と、を備える。 The method for producing the clay roof tile 10 includes the steps of preparing the clay tile glaze A and the clay tile glaze R, forming the base layer 20, and applying the clay roof glaze A and the clay tile glaze R to the base layer 20. A glazing step and a firing step for firing the clay roof tile 10.

まず、粘土瓦用釉薬Ａおよび粘土瓦用釉薬Ｒを調製する（調製工程）。具体的には、上述した割合でコージライト、α−アルミナ、ジルコンを配合し、上記のゼーゲル式で表された組成になるように釉薬原料を適宜配合し、粘土瓦用釉薬Ａを調製する。この釉薬原料には、曹長石、正長石、炭酸カルシウム、酸化マンガン、二酸化ケイ素、酸化チタンなどを含む。この粘土瓦用釉薬Ａと、適量の水と、糊剤と、をミルに投入し、混合して粘土瓦用釉薬Ａの釉薬泥漿を得る。同様に粘土瓦用釉薬Ｒを調製し、釉薬泥漿を得る。 First, glaze A for clay roof tiles and glaze R for clay roof tiles are prepared (preparation step). Specifically, cordierite, α-alumina, and zircon are blended in the proportions described above, and the glaze raw material is blended as appropriate so that the composition represented by the Zegel formula is obtained, thereby preparing glaze A for clay roof tiles. This glaze raw material includes feldspar, orthofeldspar, calcium carbonate, manganese oxide, silicon dioxide, titanium oxide and the like. The clay roofing glaze A, an appropriate amount of water, and a paste are put into a mill and mixed to obtain a clay roofing glaze A glaze slurry. Similarly, a glaze R for clay roof tiles is prepared to obtain a glaze slurry.

つぎに、粘土を主原料とする原料を混練し、瓦の形状になるように素地層２０を成形する（成形工程）。 Next, the raw material which makes clay the main raw material is knead | mixed, and the base layer 20 is shape | molded so that it may become the shape of a tile (forming process).

つぎに、粘土瓦用釉薬Ａおよび粘土瓦用釉薬Ｒを素地層２０に施釉する（施釉工程）。具体的には、素地層２０の裏面に調製工程で調製した粘土瓦用釉薬Ａの釉薬泥漿を施釉し、表面に粘土瓦用釉薬Ｒの釉薬泥漿を施釉する。 Next, the glaze A for clay roof tiles and the glaze R for clay roof tiles are applied to the base layer 20 (glazing process). Specifically, the glaze slurry of the clay tile glaze A prepared in the preparation step is applied to the back surface of the base layer 20, and the glaze slurry of the clay tile glaze R is applied to the surface.

つぎに、素地層２０に粘土用釉薬Ａおよび粘土瓦用釉薬Ｒが施釉された粘土瓦１０を炉で焼成する焼成工程を実施する。焼成工程では、粘土瓦１０をトンネル炉などで１０００℃〜１２００℃で酸化焼成する。焼成工程の後、粘土瓦１０の焼成品が得られる。 Next, a firing step is performed in which the clay tile 10 in which the base layer 20 is coated with the clay glaze A and the clay tile glaze R is fired in a furnace. In the firing step, the clay roof tile 10 is oxidized and fired at 1000 ° C. to 1200 ° C. in a tunnel furnace or the like. After the firing step, a fired product of the clay roof tile 10 is obtained.

以上述たように、第１の実施の形態の粘土瓦１０は、第１の釉薬層３０を構成する粘土瓦用釉薬Ａが、コージライト、α−アルミナ、ジルコンを所定の割合以上含み、且つ上記ゼーゲル式で表される組成に調製されることで、粘土瓦１０は、大きい曲げ破壊強度を有する。このため、粘土瓦１０が瓦に必要な曲げ破壊強度を保ちつつ、粘土瓦１０の厚みを小さくできる。これにより、粘土瓦１０の質量を小さくできる。また、粘土瓦１０は、表面に従来から用いられている粘土瓦用釉薬Ｒを施釉することで、一般の粘土瓦と同様の色彩、光沢を備える。また、粘土瓦用釉薬Ａが、コージライト、α−アルミナ、ジルコンを所定の割合以下含み、且つ上記ゼーゲル式で表される組成に調製されることで、見付け部分の第２の釉薬層４０の色調と第１の釉薬層３０の色調との違いが目立たない。 As described above, in the clay roof tile 10 according to the first embodiment, the clay roof glaze A constituting the first glaze layer 30 includes cordierite, α-alumina, zircon in a predetermined ratio or more, and By preparing the composition represented by the Zegel formula, the clay roof tile 10 has a high bending fracture strength. For this reason, the thickness of the clay roof tile 10 can be reduced while the clay roof tile 10 maintains the bending fracture strength required for the roof tile. Thereby, the mass of the clay roof tile 10 can be reduced. Further, the clay roof tile 10 is provided with the same color and gloss as a general clay roof tile by applying a conventionally used clay roof glaze R to the surface. Moreover, the glaze A for clay roof tiles contains cordierite, α-alumina, zircon at a predetermined ratio or less, and is prepared in a composition represented by the Zegel formula, so that the second glaze layer 40 of the found portion is formed. The difference between the color tone and the color tone of the first glaze layer 30 is not noticeable.

（第２の実施の形態）
第１の実施の形態では、第２の釉薬層４０が結晶系銀色釉薬から構成される粘土瓦１０について説明した。これに対して、第２の実施の形態では、第２の釉薬層４０がいぶし系銀色釉薬から構成される粘土瓦１０について説明する。なお、いぶし系銀色釉薬層を配置した粘土瓦は、「白寿」として井野瓦工業株式会社で販売されているものである。 (Second Embodiment)
In the first embodiment, the clay roof tile 10 in which the second glaze layer 40 is made of a crystalline silver glaze has been described. On the other hand, in 2nd Embodiment, the 2nd glaze layer 40 demonstrates the clay roof tile 10 comprised from a glaze type silver glaze. In addition, clay tiles with an Ibushi-based silver glaze layer are sold by Inogawara Kogyo Co., Ltd. as “Shirasu”.

第２の実施の形態の粘土瓦１０は、粘土瓦用釉薬Ｂから構成される第１の釉薬層３０と、粘土瓦用釉薬（いぶし系銀色釉薬）Ｓから構成される第２の釉薬層４０を備える。 The clay roof tile 10 according to the second embodiment includes a first glaze layer 30 composed of the glaze B for clay roof tiles and a second glaze layer 40 composed of the glaze for clay roof tiles (smoldering silver glaze) S. Is provided.

粘土瓦用釉薬Ｂは、２質量％以上６質量％以下のコージライト、または２質量％のペタライト（Ｌｉ_２ＯＡｌ_２Ｏ_３８ＳｉＯ_２）、を含み、
ゼーゲル式にて、
Ｎａ_２Ｏが０．０１モル、Ｋ_２Ｏが０．０１モル、Ｌｉ_２Ｏが０．２１モル、ＭｇＯが０．６７モル、ＣａＯが０．０２モル、ＭｎＯが０．０８モル、
Ａｌ_２Ｏ_３が０．６７モル、Ｆｅ_２Ｏ_３が０．０５モル、
ＳｉＯ_２が３．０８モル、ＴｉＯ_２が１．０１モル、ＺｒＯ_２が０．６３モル、
として表される組成から構成される。 The glaze B for clay roof includes 2% by mass or more and 6% by mass or less of cordierite, or 2% by mass of petalite (Li ₂ OAl ₂ O ₃ 8SiO ₂ ),
In the Segel formula,
Na ₂ O 0.01 mol, K ₂ O 0.01 mol, Li ₂ O 0.21 mol, MgO 0.67 mol, CaO 0.02 mol, MnO 0.08 mol,
Al ₂ O ₃ is 0.67 mol, Fe ₂ O ₃ is 0.05 mol,
SiO ₂ is 3.08 mol, TiO ₂ is 1.01 mol, ZrO ₂ is 0.63 moles,
It is comprised from the composition represented as.

粘土瓦用釉薬Ｓは、
ゼーゲル式にて、
Ｎａ_２Ｏが０．００〜０．０５モル、Ｋ_２Ｏが０．００〜０．０５モル、Ｌｉ_２Ｏが０．０１〜０．０３モル、ＭｇＯが０．０５〜０．２５モル、ＣａＯが０．００〜０．１０モル、ＭｎＯが０．３５〜１．２５モル、
Ａｌ_２Ｏ_３が０．４３〜１．０５モル、Ｆｅ_２Ｏ_３が０．００〜０．２３モル、
ＳｉＯ_２が２．０５〜４．３２モル、ＴｉＯ_２が０．５３〜１．５２モル、ＺｒＯ_２が０．３２〜１．２５モル、
として表される組成から構成される。 The glaze S for clay roof
In the Segel formula,
Na ₂ O is 0.00 to 0.05 mol, _{K 2} O is from 0.00 to 0.05 mol, Li ₂ O is 0.01 to 0.03 mol, MgO is 0.05 to 0.25 mol, 0.000 to 0.10 mole of CaO, 0.35 to 1.25 mole of MnO,
Al ₂ O ₃ is 0.43 to 1.05 mol, Fe ₂ O ₃ is 0.00 to 0.23 mol,
SiO ₂ is 2.05 to 4.32 mol, TiO ₂ is from 0.53 to 1.52 mol, ZrO ₂ is 0.32 to 1.25 mol,
It is comprised from the composition represented as.

コージライトの熱線膨張係数は、上述したように、２．６〜２．８×１０^−６／℃、融点は１４５０℃である。ペタライトの熱線膨張係数は、０．５×１０^−６／℃であり、融点は１３５０℃である。粘土瓦用釉薬Ｂが、コージライトを２質量％以上、またはペタライトを２質量％含むことで、第１の釉薬層３０の線熱膨張係数は、素地層２０の線熱膨張係数より一定以上小さくなる。また、コージライト、ペタライトの融点は、粘土瓦１０の焼成温度より高いので、焼成した際、コージライト、ペタライトが溶融せず固体のまま第１の釉薬層３０に残る。このことも、第１の釉薬層３０の線熱膨張係数を小さくすることに寄与すると考えられる。この結果、粘土瓦１０が焼成した後冷却されると、素地層２０と第１の釉薬層３０との線熱膨張係数の差により、第１の釉薬層３０にコンプレッション（圧縮応力）が加わる。これにより、粘土瓦１０の曲げ破壊強度を高めることができると考えられる。粘土瓦１０が大きい曲げ破壊強度を有することで、瓦に必要な曲げ破壊強度を保ちつつ、粘土瓦１０の厚みを小さくできる。これにより、粘土瓦１０の質量を小さくできる。
また、粘土瓦用釉薬Ｂが、コージライトを６質量％以下、またはペタライトを２質量％含むことで、見付け部分（表面と裏面の重なり部分）の第２の釉薬層４０の色調と第１の釉薬層３０の色調との違いが目立たなくなる。 As described above, the thermal expansion coefficient of cordierite is 2.6 to 2.8 × 10 ⁻⁶ / ° C., and the melting point is 1450 ° C. The thermal expansion coefficient of petalite is 0.5 × 10 ⁻⁶ / ° C., and the melting point is 1350 ° C. Since the glaze B for clay roof contains 2 mass% or more of cordierite or 2 mass% of petalite, the linear thermal expansion coefficient of the first glaze layer 30 is smaller than the linear thermal expansion coefficient of the base layer 20 by a certain amount or more. Become. Moreover, since the melting point of cordierite and petalite is higher than the firing temperature of the clay roof tile 10, cordierite and petalite do not melt and remain in the first glaze layer 30 as a solid when fired. This is also considered to contribute to reducing the linear thermal expansion coefficient of the first glaze layer 30. As a result, when the clay roof tile 10 is fired and then cooled, compression (compression stress) is applied to the first glaze layer 30 due to the difference in linear thermal expansion coefficient between the base layer 20 and the first glaze layer 30. Thereby, it is thought that the bending fracture strength of the clay roof tile 10 can be increased. Since the clay roof tile 10 has a high bending fracture strength, the thickness of the clay roof tile 10 can be reduced while maintaining the bending fracture strength required for the roof tile. Thereby, the mass of the clay roof tile 10 can be reduced.
Further, the glaze B for clay roof contains 6% by weight or less of cordierite or 2% by weight of petalite, so that the color tone and the first tone of the second glaze layer 40 in the found portion (the overlapping portion of the front surface and the back surface) can be obtained. The difference from the color tone of the glaze layer 30 becomes inconspicuous.

粘土瓦用釉薬Ｂおよび粘土瓦用釉薬Ｓのゼーゲル式による作用効果は、上述した粘土瓦用釉薬Ａのゼーゲル式による作用効果と同様である。 The operational effects of the clay roofing glaze B and the clay roofing glaze S are the same as the above-described operational effects of the clay roofing glaze A of the clay roofing glaze A.

（第３の実施の形態）
第３の実施の形態では、第２の釉薬層４０が半光沢黒色（ブラックマット）釉薬から構成される粘土瓦１０について説明する。第３の実施の形態の粘土瓦１０は、粘土瓦用釉薬Ｃから構成される第１の釉薬層３０と、粘土瓦用釉薬（半光沢黒色釉薬）Ｔから構成される第２の釉薬層４０を備える。 (Third embodiment)
In the third embodiment, the clay roof tile 10 in which the second glaze layer 40 is composed of a semi-glossy black (black matte) glaze will be described. The clay roof tile 10 of the third embodiment includes a first glaze layer 30 composed of a clay roofing glaze C and a second glaze layer 40 composed of a clay roofing glaze (semi-glossy black glaze) T. Is provided.

粘土瓦用釉薬Ｃは、４質量％以上６質量％以下のコージライトを含み、
ゼーゲル式にて、
Ｎａ_２Ｏが０．０１モル、Ｋ_２Ｏが０．０１モル、ＭｇＯが０．０２モル、ＣａＯが０．０７モル、ＭｎＯが０．８０モル、ＢａＯが０．０９モル、
Ａｌ_２Ｏ_３が０．２７モル、Ｆｅ_２Ｏ_３が０．０２モル、
ＳｉＯ_２が１．６６モル、ＴｉＯ_２が０．１９モル、ＺｒＯ_２が０．１３、Ｂ_２Ｏ_３が０．０４モル、
として表される組成から構成される。 The glaze C for clay roof tiles includes 4% by weight to 6% by weight of cordierite,
In the Segel formula,
Na ₂ O 0.01 mol, K ₂ O 0.01 mol, MgO 0.02 mol, CaO 0.07 mol, MnO 0.80 mol, BaO 0.09 mol,
Al ₂ O ₃ is 0.27 mol, Fe ₂ O ₃ is 0.02 mol,
SiO ₂ is 1.66 mol, TiO ₂ is 0.19 mol, ZrO ₂ is _0.13, B 2 _{O 3} is 0.04 mol,
It is comprised from the composition represented as.

粘土瓦用釉薬Ｔは、
ゼーゲル式にて、
Ｎａ_２Ｏが０．０１モル、Ｋ_２Ｏが０．０１モル、ＭｇＯが０．０１モル、ＣａＯが０．０７モル、ＭｎＯが０．８０モル、ＢａＯが０．１０モル、
Ａｌ_２Ｏ_３が０．２５モル、Ｆｅ_２Ｏ_３が０．０２モル、
ＳｉＯ_２が１．６０モル、ＴｉＯ_２が０．１９モル、ＺｒＯ_２が０．１３、Ｂ_２Ｏ_３が０．０４モル、
として表される組成から構成される。 Glaze T for clay roof
In the Segel formula,
Na ₂ O 0.01 mol, K ₂ O 0.01 mol, MgO 0.01 mol, CaO 0.07 mol, MnO 0.80 mol, BaO 0.10 mol,
Al ₂ O ₃ is 0.25 mol, Fe ₂ O ₃ is 0.02 mol,
SiO ₂ is 1.60 mol, TiO ₂ is 0.19 mol, ZrO ₂ is 0.13, B ₂ O ₃ is 0.04 mol,
It is comprised from the composition represented as.

粘土瓦用釉薬Ｃが、コージライトを４質量％以上含むことで、第１の釉薬層３０の線熱膨張係数は、素地層２０の線熱膨張係数より一定以上小さくなる。また、コージライトの融点は、粘土瓦１０の焼成温度より高いので、焼成した際、コージライトが溶融せず固体のまま第１の釉薬層３０に残る。このことも、第１の釉薬層３０の線熱膨張係数を小さくすることに寄与すると考えられる。この結果、粘土瓦１０が焼成した後冷却されると、素地層２０と第１の釉薬層３０との線熱膨張係数の差により、第１の釉薬層３０にコンプレッション（圧縮応力）が加わる。これにより、粘土瓦１０の曲げ破壊強度を高めることができると考えられる。粘土瓦１０が大きい曲げ破壊強度を有することで、瓦に必要な曲げ破壊強度を保ちつつ、粘土瓦１０の厚みを小さくできる。これにより、粘土瓦１０の質量を小さくできる。
また、粘土瓦用釉薬Ｃが、コージライトを６質量％以下含むことで、見付け部分（表面と裏面の重なり部分）の第２の釉薬層４０の色調と第１の釉薬層３０の色調との違いが目立たなくなる。 When the glaze C for clay roof contains 4 mass% or more of cordierite, the linear thermal expansion coefficient of the first glaze layer 30 becomes smaller than the linear thermal expansion coefficient of the base layer 20 by a certain amount or more. Moreover, since the melting point of cordierite is higher than the firing temperature of the clay roof tile 10, the cordierite does not melt and remains in the first glaze layer 30 as a solid when fired. This is also considered to contribute to reducing the linear thermal expansion coefficient of the first glaze layer 30. As a result, when the clay roof tile 10 is fired and then cooled, compression (compression stress) is applied to the first glaze layer 30 due to the difference in linear thermal expansion coefficient between the base layer 20 and the first glaze layer 30. Thereby, it is thought that the bending fracture strength of the clay roof tile 10 can be increased. Since the clay roof tile 10 has a high bending fracture strength, the thickness of the clay roof tile 10 can be reduced while maintaining the bending fracture strength required for the roof tile. Thereby, the mass of the clay roof tile 10 can be reduced.
Moreover, the glaze C for clay tiles contains 6 mass% or less of cordierite, so that the color tone of the second glaze layer 40 and the color tone of the first glaze layer 30 in the found portion (the overlapping portion of the front surface and the back surface) The difference is less noticeable.

粘土瓦用釉薬Ｃおよび粘土瓦用釉薬Ｔのゼーゲル式による作用効果は、上述した粘土瓦用釉薬Ａのゼーゲル式による作用効果と同様である。 The operational effects of the clay tile glaze C and the clay roof glaze T according to the Zegel formula are the same as the above-described operational effects of the clay tile glaze A of the clay tile glaze A.

（第４の実施の形態）
第４の実施の形態では、第２の釉薬層４０がハイシルバー釉薬から構成される粘土瓦１０について説明する。第４の実施の形態の粘土瓦１０は、粘土瓦用釉薬Ｄから構成される第１の釉薬層３０と、粘土瓦用釉薬（ハイシルバー釉薬）Ｕから構成される第２の釉薬層４０を備える。 (Fourth embodiment)
4th Embodiment demonstrates the clay roof tile 10 in which the 2nd glaze layer 40 is comprised from a high silver glaze. The clay roof tile 10 according to the fourth embodiment includes a first glaze layer 30 composed of a clay tile glaze D and a second glaze layer 40 composed of a clay tile glaze (high silver glaze) U. Prepare.

粘土瓦用釉薬Ｄは、
ゼーゲル式にて、
Ｎａ_２Ｏが０．００モル超０．０３モル以下、Ｋ_２Ｏが０．００モル超０．０１モル以下、ＣａＯが０．０２モル、Ｌｉ_２Ｏが０．９６モル以上０．９９モル以下、
Ａｌ_２Ｏ_３が１．００モル以上２．００モル以下、
ＳｉＯ_２が６．３１モル以上８．３１モル以下、
として表される組成から構成されるとよい。 Glaze D for clay roof
In the Segel formula,
Na ₂ O more than 0.00 mol 0.03 mol or less, K ₂ O more than 0.00 mol 0.01 mol or less, CaO 0.02 mol, Li ₂ O 0.96 mol or more and 0.99 mol Less than,
Al ₂ O ₃ is 1.00 mol or more and 2.00 mol or less,
SiO ₂ is 6.31 mol or more and 8.31 mol or less,
It is good to be comprised from the composition represented as.

また、粘土瓦用釉薬Ｄは、
１質量％以上７質量％以下のα−アルミナ、１質量％以上２質量％以下のジルコン、１質量％以上１００質量％未満のペタライト、または１質量％以上２０％以下のスポジューメン（Ｌｉ_２ＯＡｌ_２Ｏ_３４ＳｉＯ_２）を含むとよい。 In addition, glaze D for clay roof
1% by mass or more and 7% by mass or less α-alumina, 1% by mass or more and 2% by mass or less zircon, 1% by mass or more and less than 100% by mass petalite, or 1% by mass or more and less than 20% spodomen (Li ₂ OAl ₂ O ₃ 4SiO ₂ ).

粘土瓦用釉薬Ｕは、
ゼーゲル式にて、
Ｎａ_２Ｏが０．１１モル、Ｋ_２Ｏが０．１７モル、ＭｇＯが０．０６モル、ＣａＯが０．６５モル、ＭｎＯが０．０１モル、
Ａｌ_２Ｏ_３が０．１７モル、Ｆｅ_２Ｏ_３が０．０２モル、
ＳｉＯ_２が２．３４モル、ＴｉＯ_２が０．０３モル、Ｂ_２Ｏ_３が０．５５モル、Ｃｒ_２Ｏ_３が０．０２モル、
として表される組成から構成される。 The glaze U for clay tile is
In the Segel formula,
Na ₂ O 0.11 mol, _{K 2} O 0.17 mol, MgO 0.06 mol, CaO 0.65 mole, MnO is 0.01 mol,
Al ₂ O ₃ is 0.17 mol, Fe ₂ O ₃ is 0.02 mol,
SiO ₂ is 2.34 mol, TiO ₂ is 0.03 mol, B ₂ O ₃ is 0.55 mol, Cr ₂ O ₃ is 0.02 mol,
It is comprised from the composition represented as.

粘土瓦用釉薬Ｄおよび粘土瓦用釉薬Ｕのゼーゲル式による作用効果は、上述した粘土瓦用釉薬Ａのゼーゲル式による作用効果と同様である。 The operational effects of the clay roofing glaze D and the clay roofing glaze U are the same as the above-described operational effects of the clay roofing glaze A of the clay roofing glaze A.

粘土瓦用釉薬Ｄは、上記ゼーゲル式で示されるＳｉＯ_２の含有率が大きいため、粘土瓦用釉薬Ｄの溶融温度が高くなり、粘土瓦１０の曲げ破壊強度を高めることができると考えられる。また、α−アルミナを１質量％以上、ジルコンを１質量％以上、ペタライトを１質量％以上、またはスポジューメンを１質量％含むことで、粘土瓦１０の曲げ破壊強度をより高めることができると考えられる。粘土瓦１０が大きい曲げ破壊強度を有することで、瓦に必要な曲げ破壊強度を保ちつつ、粘土瓦１０の厚みを小さくできる。これにより、粘土瓦１０の質量を小さくできる。
また、粘土瓦用釉薬Ｄが、α−アルミナを７質量％以下、ジルコンを２質量％以下、ペタライトを１００質量％未満、またはスポジューメンを２０質量％以下含むことで、見付け部分（表面と裏面の重なり部分）の第２の釉薬層４０の色調と第１の釉薬層３０の色調との違いが目立たなくなる。 It is considered that the clay roofing glaze D has a high content of SiO ₂ represented by the Zegel formula, so that the melting temperature of the clay roofing glaze D is increased and the bending fracture strength of the clay roofing tile 10 can be increased. Further, it is considered that the bending fracture strength of the clay roof tile 10 can be further increased by including 1% by mass or more of α-alumina, 1% by mass or more of zircon, 1% by mass or more of petalite, or 1% by mass of spodumene. It is done. Since the clay roof tile 10 has a high bending fracture strength, the thickness of the clay roof tile 10 can be reduced while maintaining the bending fracture strength required for the roof tile. Thereby, the mass of the clay roof tile 10 can be reduced.
Further, the glaze D for clay roof contains 7 mass% or less of α-alumina, 2 mass% or less of zircon, less than 100 mass% of petalite, or 20 mass% or less of spodumene. The difference between the color tone of the second glaze layer 40 in the overlapping portion) and the color tone of the first glaze layer 30 becomes inconspicuous.

（変形例）
本発明は上記の実施の形態に限定されるものではなく、様々な実施形態を包含する。上記実施の形態では、第１の釉薬層３０が、粘土瓦用釉薬Ａ〜Ｄから構成され、第２の釉薬層４０が、粘土瓦用釉薬Ｒ〜Ｕから構成された粘土瓦１０について説明したが、第１の釉薬層３０と第２の釉薬層４０とは、粘土瓦用釉薬Ａ〜Ｃから構成されてもよい。 (Modification)
The present invention is not limited to the above-described embodiment, and includes various embodiments. In the said embodiment, the 1st glaze layer 30 comprised the glazes A-D for clay roof tiles, and the 2nd glaze layer 40 demonstrated the clay roof tile 10 comprised from the glazes R-U for clay roof tiles. However, the 1st glaze layer 30 and the 2nd glaze layer 40 may be comprised from the glazes AC for clay roof tiles.

以下に、本発明を実施例に基づき、さらに詳細に説明するが、本発明はこれらに限定されるものではない。 Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

（結晶系銀色釉薬を表面に施釉した粘土瓦）
従来用いられている結晶系銀色釉薬を表面に、実施例の粘土瓦用釉薬を裏面に施釉した粘土瓦の実施例について説明する。まず、表１に示すように、コージライトを２質量％含み、ゼーゲル式にて、Ｎａ_２Ｏが０．０１モル、Ｋ_２Ｏが０．０１モル、ＭｇＯが０．０５モル、ＣａＯが０．１８モル、ＭｎＯが０．７６モル、Ａｌ_２Ｏ_３が０．１６モル、Ｆｅ_２Ｏ_３が０．０３モル、Ｂ_２Ｏ_３が０．０８モル、ＳｉＯ_２が１．３３モル、ＴｉＯ_２が０．２２モル、ＺｒＯ_２が０．３１モル、の割合になるように、原料を適宜配合し実施例１の粘土瓦用釉薬を調製した。ここで用いた原料は、曹長石、正長石、炭酸カルシウム、酸化マンガン、二酸化ケイ素、酸化チタンなどを含む。実施例１の粘土瓦用釉薬と水と糊剤とをミルに投入し、混合して実施例１の釉薬泥漿を得た。実施例２〜実施例１３および比較例１の粘土瓦用釉薬についても表１に示す組成成分、含有率に基づいて、実施例１の粘土瓦用釉薬と同様に調製し、実施例２〜実施例１３、比較例１の釉薬泥漿を得た。なお、比較例１の粘土瓦用釉薬は、結晶系銀色釉薬である。また、釉薬泥漿中粘土瓦用釉薬は、５５質量％、水は、４５質量％、糊剤は、０．０５質量％とした。また、表１中コージライト、α−アルミナ、ジルコンの「−」は、配合しないことを示す。また、表１中比較例１の曲げ破壊強度の「−」は、比較対象であることを示す。 (Clay tile with a crystal silver glaze on the surface)
An example of a clay roof tile in which a conventionally used crystalline silver glaze is applied on the surface and the clay roof glaze of the embodiment on the back surface will be described. First, as shown in Table 1, it contains 2% by mass of cordierite, and in the Zegel formula, Na ₂ O is 0.01 mol, K ₂ O is 0.01 mol, MgO is 0.05 mol, and CaO is 0. .18 mol, MnO 0.76 mol, Al ₂ O ₃ 0.16 mol, Fe ₂ O ₃ 0.03 mol, B ₂ O ₃ 0.08 mol, SiO ₂ 1.33 mol, TiO _The material for the clay roof tile of Example 1 was prepared by appropriately blending the raw materials so that ₂ was 0.22 mol and ZrO ₂ was 0.31 mol. The raw materials used here include feldspar, orthofeldspar, calcium carbonate, manganese oxide, silicon dioxide, titanium oxide and the like. The glaze for clay roof tile of Example 1, water, and the paste were put into a mill and mixed to obtain the glaze slurry of Example 1. The glazes for clay roof tiles of Examples 2 to 13 and Comparative Example 1 were also prepared in the same manner as the glaze for clay roof tiles of Example 1 based on the composition components and contents shown in Table 1, and Examples 2 to The glaze slurry of Example 13 and Comparative Example 1 was obtained. In addition, the glaze for clay roofs of the comparative example 1 is a crystalline silver glaze. Further, the glaze for clay roof tiles in the glaze slurry was 55% by mass, water was 45% by mass, and the paste was 0.05% by mass. In Table 1, “-” of cordierite, α-alumina, and zircon indicates that they are not blended. Moreover, "-" of the bending fracture strength of Comparative Example 1 in Table 1 indicates that it is a comparison target.

つぎに、粘土を主原料とする原料を混練し、ＪＩＳＡ５２０８Ｊ形桟瓦５３Ａに基づく瓦の形状、大きさになるように素地層を成形した。焼成後の１枚当りの瓦の質量は、２．４０Ｋｇとした。素地層の表面に比較例１の釉薬泥漿を施釉し、裏面に実施例１の釉薬泥漿を施釉し、実施例１の粘土瓦を得た。実施例１の粘土瓦と同様に、素地層の表面に比較例１の釉薬泥漿を施釉し、裏面に実施例２〜実施例１３の釉薬泥漿をそれぞれ施釉し、実施例２〜実施例１３の粘土瓦をそれぞれ得た。また、素地層の表面および裏面に比較例１の釉薬泥漿を施釉し、比較例１の粘土瓦を得た。実施例１〜実施例１３、比較例１の釉薬釉薬泥漿の施釉量は、粘土瓦用釉薬換算で７３０ｇ／ｍ^２とした。つぎに、素地層に釉薬泥漿が施釉された実施例１〜実施例１３、比較例１の粘土瓦をトンネル炉で酸化焼成した。焼成温度は、１１２０℃とし、焼成時間は、１６時間とした。焼成工程の後、実施例１〜実施例１３、比較例１の粘土瓦の焼成品が得られた。 Next, the raw material which makes clay the main raw material was knead | mixed, and the base layer was shape | molded so that it might become the shape and magnitude | size of a tile based on JIS A5208 J-shaped roof tile 53A. The mass of the tile per sheet after firing was 2.40 kg. The glaze slurry of Comparative Example 1 was glazed on the surface of the base layer and the glaze slurry of Example 1 was glazed on the back surface to obtain the clay roof tile of Example 1. Similarly to the clay roof tile of Example 1, the glaze slurry of Comparative Example 1 is applied to the surface of the base layer, and the glaze slurry of Examples 2 to 13 is applied to the back surface, respectively. Each clay tile was obtained. Further, the glaze slurry of Comparative Example 1 was applied to the front and back surfaces of the base layer to obtain the clay roof tile of Comparative Example 1. The amount of glazing glaze slurry of Examples 1 to 13 and Comparative Example 1 was 730 g / m ^{2 in} terms of glaze for clay roof tiles. Next, the clay tiles of Examples 1 to 13 and Comparative Example 1 in which glaze sludge was applied to the base layer were oxidized and fired in a tunnel furnace. The firing temperature was 1120 ° C., and the firing time was 16 hours. After the firing step, fired products of the clay tiles of Examples 1 to 13 and Comparative Example 1 were obtained.

［釉薬の色調］
焼成後の実施例１〜実施例１３、比較例１の粘土瓦の目付け部分の裏面の釉薬色調と裏面の釉薬色調との違いを目視検査した。目付け部分の裏面の釉薬色調と裏面の釉薬色調との違いが目立たない場合を良好○（○印）、目付け部分の裏面の釉薬色調と裏面の釉薬色調とが異なる場合を不良△（△印）、目付け部分の裏面の釉薬色調と裏面の釉薬色調とがかけ離れる場合を不良×（×印）とした。 [Color tone of glaze]
The difference between the glaze color tone on the back surface and the glaze color tone on the back surface of the clay roof tiles of Examples 1 to 13 and Comparative Example 1 after firing was visually inspected. Good if the difference between the glaze color on the back of the weighted area and the glaze color on the back is inconspicuous ○ (○ mark), bad if the glaze color on the back of the weighted area is different from the glaze color on the back △ (△ mark) The case where the glaze color tone on the back surface of the basis weight part and the glaze color tone on the back surface are separated from each other was defined as defective x (x mark).

［曲げ破壊強度］
焼成後の実施例１〜実施例１３、比較例１の粘土瓦の曲げ破壊強度を測定した。曲げ破壊強度の測定は、ＪＩＳＡ５２０８で定められた方法により実施した。具体的には、図２（Ａ）、図２（Ｂ）に示すように、水平な台１００の上に直径φ１＝３０ｍｍの丸棒１１０Ａと、直径φ２＝３０ｍｍの丸棒１１０Ｂを平行に載置する。丸棒１１０Ａの軸と１１０Ｂの軸との間隔ｄ１は、２００ｍｍである。その上に粘土瓦１０を載置する。その上に直径φ３＝３０ｍｍの丸棒１１０Ｃを丸棒１１０Ａ、１１０Ｂに平行になるように粘土瓦１０に載置する。丸棒１１０Ｃを載置する位置は、水平な台１００を上から見て、丸棒１１０Ａ、１１０Ｂから間隔ｄ２＝間隔ｄ３＝１００ｍｍ離れた位置である。この状態で、上から丸棒１１０Ｃに徐々に力を加え、粘土瓦１０が割れない最大の丸棒１１０Ｃを押し当てる力を測定し、この力を曲げ破壊強度とした。測定結果を比較例１と比較して、曲げ破壊荷重が１２２％以上（３０００Ｎ以上）であるものを優良◎（◎印）、曲げ破壊荷重が１１０％以上（２７００Ｎ以上）１２２％未満であるものを良好○（○印）、曲げ破壊荷重が１１０％未満であるものを不良△（△印）とした。 [Bending fracture strength]
The bending fracture strength of the clay roof tiles of Examples 1 to 13 and Comparative Example 1 after firing was measured. The bending fracture strength was measured by the method defined in JIS A5208. Specifically, as shown in FIGS. 2A and 2B, a round bar 110A having a diameter φ1 = 30 mm and a round bar 110B having a diameter φ2 = 30 mm are mounted in parallel on a horizontal base 100. Put. The distance d1 between the axis of the round bar 110A and the axis of 110B is 200 mm. A clay roof tile 10 is placed thereon. A round bar 110C having a diameter φ3 = 30 mm is placed on the clay tile 10 so as to be parallel to the round bars 110A and 110B. The position where the round bar 110C is placed is a position where the distance d2 = the distance d3 = 100 mm away from the round bars 110A and 110B when the horizontal base 100 is viewed from above. In this state, a force was gradually applied to the round bar 110C from above, and the force pressing the largest round bar 110C at which the clay roof tile 10 was not broken was measured, and this force was defined as the bending fracture strength. Compared with the measurement results of Comparative Example 1, those having a bending fracture load of 122% or more (3000 N or more) are excellent ◎ (◎), bending fracture load is 110% or more (2700 N or more) and less than 122% Was good (circle), and the one having a bending fracture load of less than 110% was regarded as defective Δ (triangle).

表１に示すように、釉薬の色調は、実施例１〜実施例３、実施例６、実施例７、実施例１０、実施例１１の粘土瓦で良好○であった。これは、コージライト、α−アルミナ、ジルコンの含有率が所定割合以下であったため、釉薬の色調の変化が少なかったためと考えられる。一方、実施例４、実施例８、実施例１２、実施例１３の粘土瓦の色調は、不良△であり、実施例５、実施例９の粘土瓦の色調は、不良×であった。これは、コージライト、α−アルミナ、ジルコンの含有率が所定割合以上であったため釉薬の色調が変化したためと考えられる。
また、曲げ破壊強度は、実施例３、実施例７、実施例１１の粘土瓦は優良◎であり、実施例２、実施例４〜実施例６、実施例８〜実施例１０、実施例１２、実施例１３の粘土瓦は、良好○であった。これは、コージライトの含有率が所定割合以上であったため、釉薬層の線熱膨張係数が小さくなったため、またはα−アルミナ、ジルコンの含有率が所定割合以上であったため、釉薬層の密度が大きくなったためと考えられる。一方、実施例１の粘土瓦は不良△であった。これは、コージライトの含有率が所定割合以下であったため、釉薬層の線熱膨張係数が十分小さくならなかったためと考えられる。 As shown in Table 1, the color tone of the glaze was good in the clay roof tiles of Examples 1 to 3, Example 6, Example 7, Example 10, and Example 11. This is presumably because the change in the color tone of the glaze was small because the content of cordierite, α-alumina, and zircon was not more than a predetermined ratio. On the other hand, the color tone of the clay roof tiles of Example 4, Example 8, Example 12, and Example 13 was poor Δ, and the color tone of the clay roof tiles of Examples 5 and 9 was poor x. This is considered to be because the color tone of the glaze changed because the content ratios of cordierite, α-alumina, and zircon were not less than a predetermined ratio.
In addition, the bending fracture strength of the clay roofs of Example 3, Example 7, and Example 11 is excellent. Example 2, Example 4 to Example 6, Example 8 to Example 10, Example 12 The clay roof tile of Example 13 was good. This is because the cordierite content was a predetermined ratio or more, the linear thermal expansion coefficient of the glaze layer was reduced, or the content of α-alumina and zircon was a predetermined ratio or more, so the density of the glaze layer was This is thought to be due to the increase. On the other hand, the clay roof of Example 1 was defective Δ. This is thought to be because the linear thermal expansion coefficient of the glaze layer did not become sufficiently small because the cordierite content was below a predetermined ratio.

（いぶし系銀色釉薬を表面に施釉した粘土瓦）
従来用いられているいぶし系銀色釉薬を表面に、実施例の粘土瓦用釉薬を裏面に施釉した粘土瓦の実施例について説明する。実施例１４〜実施例２０、比較例２の粘土瓦用釉薬を、表２に示す組成成分、含有率に基づいて、実施例１の粘土瓦用釉薬と同様に調製した。この粘土瓦用釉薬と水と糊剤とをミルに投入し、混合して実施例１４〜実施例２０、比較例２の釉薬泥漿を得た。なお、比較例２の粘土瓦用釉薬は、いぶし系銀色釉薬である。また、表２中コージライト、ペタライトの「−」は、配合しないことを示す。また、比較例２の曲げ破壊強度の「−」は、比較対象であることを示す。 (Clay roof tiles with a silver-based silver glaze on the surface)
A description will be given of an example of a clay roof tile in which a conventionally used silver-based silver glaze is applied to the surface and the clay roof glaze of the embodiment is applied to the back surface. The clay roof glazes of Examples 14 to 20 and Comparative Example 2 were prepared in the same manner as the clay roof glaze of Example 1 based on the compositional components and contents shown in Table 2. The glaze for clay roof tile, water and glue were put into a mill and mixed to obtain glaze slurries of Examples 14 to 20 and Comparative Example 2. In addition, the glaze for clay roofs of the comparative example 2 is an smoldering silver glaze. In Table 2, "-" for cordierite and petalite indicates that they are not blended. Further, “−” in the bending fracture strength of Comparative Example 2 indicates that it is a comparison target.

つぎに、粘土を主原料とする原料を混練し、実施例１と同様に瓦の形状になるように素地層を成形した。焼成後の１枚当りの瓦の質量は、２．４０Ｋｇとした。素地層の表面に比較例２の釉薬泥漿を施釉し、裏面に実施例１４の釉薬泥漿を施釉し、実施例１４の粘土瓦を得た。実施例１４の粘土瓦と同様に、素地層の表面に比較例２の釉薬泥漿を施釉し、裏面に実施例１５〜実施例２０の釉薬泥漿をそれぞれ施釉し、実施例１５〜実施例２０の粘土瓦をそれぞれ得た。また、素地層の表面および裏面に比較例２の釉薬泥漿を施釉し、比較例２の粘土瓦を得た。実施例１４〜実施例２０、比較例２の釉薬釉薬泥漿の施釉量は、実施例１と同様である。
つぎに、実施例１４〜実施例２０、比較例２の粘土瓦をトンネル炉で酸化焼成した。焼成温度、焼成時間は、実施例１と同様である。焼成工程の後、実施例１４〜実施例２０、比較例２の粘土瓦の焼成品が得られた。 Next, a raw material containing clay as a main raw material was kneaded, and a base layer was formed so as to have a tile shape as in Example 1. The mass of the tile per sheet after firing was 2.40 kg. The glaze slurry of Comparative Example 2 was applied to the surface of the base layer, and the glaze slurry of Example 14 was applied to the back surface to obtain the clay roof tile of Example 14. Similarly to the clay roof tile of Example 14, the glaze slurry of Comparative Example 2 was applied to the surface of the base layer, and the glaze slurry of Examples 15 to 20 was applied to the back surface, respectively. Each clay tile was obtained. Further, the glaze slurry of Comparative Example 2 was applied to the front and back surfaces of the base layer to obtain the clay roof tile of Comparative Example 2. The amount of glaze of the glaze glaze slurry of Examples 14 to 20 and Comparative Example 2 is the same as that of Example 1.
Next, the clay roof tiles of Examples 14 to 20 and Comparative Example 2 were oxidized and fired in a tunnel furnace. The firing temperature and firing time are the same as in Example 1. After the firing step, fired products of the clay tiles of Examples 14 to 20 and Comparative Example 2 were obtained.

［釉薬の色調］
焼成後の実施例１４〜実施例２０、比較例２の粘土瓦の目付け部分の裏面の釉薬色調と裏面の釉薬色調との違いを実施例１と同様の評価基準で目視検査した。 [Color tone of glaze]
The difference between the glaze color tone of the back surface and the glaze color tone of the back surface of the clay tiles of Examples 14 to 20 and Comparative Example 2 after firing was visually inspected according to the same evaluation criteria as in Example 1.

［曲げ破壊強度］
焼成後の実施例１４〜実施例２０、比較例２の粘土瓦の曲げ破壊強度を実施例１と同様に測定した。測定結果を比較例２と比較して、曲げ破壊荷重が１２３％以上（３０００Ｎ以上）であるものを優良◎（◎印）、曲げ破壊荷重が１１０％以上（２６７３Ｎ以上）１２３％未満であるものを良好○（○印）、曲げ破壊荷重が１１０％未満であるものを不良△（△印）とした。 [Bending fracture strength]
The bending fracture strength of the clay roof tiles of Examples 14 to 20 and Comparative Example 2 after firing was measured in the same manner as in Example 1. Compared with the measurement result of Comparative Example 2, the one having a bending fracture load of 123% or more (3000N or more) is excellent ◎ (◎ mark), and the bending fracture load is 110% or more (2673N or more) less than 123% Was good (circle), and the one having a bending fracture load of less than 110% was regarded as defective Δ (triangle).

表２に示すように、釉薬の色調は、実施例１４〜実施例１９の粘土瓦で良好○であった。これは、コージライト、ペタライトの含有率が所定割合以下であったため、釉薬の色調の変化が少なかったためと考えられる。一方、実施例２０の粘土瓦の色調は、不良△であった。これは、ペタライトの含有率が所定割合以上であったため釉薬の色調が変化したためと考えられる。
また、曲げ破壊強度は、実施例１５〜実施例１７の粘土瓦で優良◎であり、実施例１４、実施例１９、実施例２０で良好○であった。これは、コージライト、ペタライトの含有率が所定割合以上であったため、釉薬層の線熱膨張係数が小さくなったためと考えられる。一方、実施例１８の粘土瓦は不良△であった。これは、ペタライトの含有率が所定割合以下であったため、釉薬層の線熱膨張係数が十分小さくならなかったためと考えられる。 As shown in Table 2, the color tone of the glaze was good in the clay roof tiles of Examples 14 to 19. This is presumably because the change in the color tone of the glaze was small because the cordierite and petalite content was less than a predetermined ratio. On the other hand, the color tone of the clay roof of Example 20 was poor Δ. This is presumably because the color tone of the glaze changed because the petalite content was a predetermined ratio or more.
Moreover, the bending fracture strength was excellent in the clay roofs of Examples 15 to 17, and excellent in Examples 14, 19, and 20. This is thought to be because the linear thermal expansion coefficient of the glaze layer was reduced because the content of cordierite and petalite was a predetermined ratio or more. On the other hand, the clay tile of Example 18 was poor Δ. This is presumably because the linear thermal expansion coefficient of the glaze layer did not become sufficiently small because the petalite content was less than a predetermined ratio.

（半光沢黒色（ブラックマット）釉薬を表面に施釉した粘土瓦）
従来用いられている半光沢黒色釉薬を表面に、実施例の粘土瓦用釉薬を裏面に施釉した粘土瓦について説明する。実施例２１〜実施例２４、比較例３の粘土瓦用釉薬を、表３に示す組成成分、含有率が異なる以外は、実施例１の粘土瓦用釉薬と同様に調製した。この粘土瓦用釉薬と水と糊剤とをミルに投入し、混合して実施例２１〜実施例２４、比較例３の釉薬泥漿を得た。なお、比較例３の粘土瓦用釉薬は、半光沢黒色釉薬である。また、表３中コージライトの「−」は、配合しないことを示す。また、比較例３の曲げ破壊強度の「−」は、比較対象であることを示す。 (Clay tiles with a semi-glossy black matte glaze on the surface)
Description will be made on a clay roof tile in which a conventionally used semi-gloss black glaze is applied on the surface and the clay tile glaze of the embodiment is applied on the back surface. The clay roofing glazes of Examples 21 to 24 and Comparative Example 3 were prepared in the same manner as the clay roofing glaze of Example 1 except that the composition components and contents shown in Table 3 were different. The glaze for clay roof tile, water and paste were put into a mill and mixed to obtain glaze sludges of Examples 21 to 24 and Comparative Example 3. In addition, the clay tile glaze of the comparative example 3 is a semi-glossy black glaze. Moreover, "-" of cordierite in Table 3 indicates that it is not blended. Further, “−” in the bending fracture strength of Comparative Example 3 indicates that it is a comparison target.

つぎに、粘土を主原料とする原料を混練し、実施例１と同様の瓦の形状になるように素地層を成形した。焼成後の１枚当りの瓦の質量は、２．４０Ｋｇとした。素地層の表面に比較例３の釉薬泥漿を施釉し、裏面に実施例２１の釉薬泥漿を施釉し、実施例２１の粘土瓦を得た。実施例２１の粘土瓦と同様に、素地層の表面に比較例３の釉薬泥漿を施釉し、裏面に実施例２２〜実施例２４の釉薬泥漿をそれぞれ施釉し、実施例２２〜実施例２４の粘土瓦をそれぞれ得た。また、素地層の表面および裏面に比較例３の釉薬泥漿を施釉し、比較例３の粘土瓦を得た。実施例２１〜実施例２４、比較例３の釉薬釉薬泥漿の施釉量は、実施例１と同様である。
つぎに、実施例２１〜実施例２４、比較例３の粘土瓦をトンネル炉で酸化焼成した。焼成温度、焼成時間は、実施例１と同様である。焼成工程の後、実施例２１〜実施例２４、比較例３の粘土瓦の焼成品が得られた。 Next, a raw material mainly composed of clay was kneaded, and a base layer was formed so as to have the same tile shape as in Example 1. The mass of the tile per sheet after firing was 2.40 kg. The glaze slurry of Comparative Example 3 was applied to the surface of the base layer, and the glaze slurry of Example 21 was applied to the back surface to obtain the clay roof of Example 21. Similarly to the clay roof tile of Example 21, the glaze slurry of Comparative Example 3 was applied to the surface of the base layer, and the glaze slurry of Examples 22 to 24 was applied to the back surface, respectively. Each clay tile was obtained. Further, the glaze slurry of Comparative Example 3 was applied to the front and back surfaces of the base layer to obtain the clay roof tile of Comparative Example 3. The amount of glaze of the glaze glaze slurry of Examples 21 to 24 and Comparative Example 3 is the same as that of Example 1.
Next, the clay roof tiles of Examples 21 to 24 and Comparative Example 3 were oxidized and fired in a tunnel furnace. The firing temperature and firing time are the same as in Example 1. After the firing step, fired products of clay roof tiles of Examples 21 to 24 and Comparative Example 3 were obtained.

［釉薬の色調］
焼成後の実施例２１〜実施例２４、比較例３の粘土瓦の目付け部分の裏面の釉薬色調と裏面の釉薬色調との違いを実施例１と同様の評価基準で目視検査した。 [Color tone of glaze]
The difference between the glaze color tone on the back surface and the glaze color tone on the back surface of the clay tiles of Examples 21 to 24 and Comparative Example 3 after firing was visually inspected according to the same evaluation criteria as in Example 1.

［曲げ破壊強度］
焼成後の実施例２１〜実施例２４、比較例３の粘土瓦の曲げ破壊強度を実施例１と同様に測定した。測定結果を比較例３と比較して、曲げ破壊荷重が１３０％以上（３０００Ｎ以上）であるものを優良◎（◎印）、曲げ破壊荷重が１１０％以上（２５４４Ｎ以上）１３０％未満であるものを良好○（○印）、曲げ破壊荷重が１１０％未満であるものを不良△（△印）とした。 [Bending fracture strength]
The bending fracture strength of the clay roof tiles of Examples 21 to 24 and Comparative Example 3 after firing was measured in the same manner as in Example 1. Compared with Comparative Example 3, the measurement result is excellent when the bending fracture load is 130% or more (3000N or more), and the bending fracture load is 110% or more (2544N or more) and less than 130%. Was good (circle), and the one having a bending fracture load of less than 110% was regarded as defective Δ (triangle).

表３に示すように、釉薬の色調は、実施例２１〜実施例２４の粘土瓦で良好○であった。これは、コージライトの含有率が所定割合以下であったため、釉薬の色調の変化が少なかったためと考えられる。
また、曲げ破壊強度は、実施例２３の粘土瓦で優良◎であり、実施例２２、実施例２４の粘土瓦で良好○であった。これは、コージライトの含有率が所定割合以上であったため、釉薬層の線熱膨張係数が小さくなったためと考えられる。一方、実施例２１の粘土瓦は不良△であった。これは、コージライトの含有率が所定割合以下であったため、釉薬層の線熱膨張係数が十分小さくならなかったためと考えられる。 As shown in Table 3, the color tone of the glaze was good with the clay roof tiles of Examples 21 to 24. This is thought to be because the change in the color tone of the glaze was small because the cordierite content was less than a predetermined ratio.
Further, the bending fracture strength was excellent in the clay roof tile of Example 23 and excellent in the clay roof tiles of Examples 22 and 24. This is considered to be because the linear thermal expansion coefficient of the glaze layer was reduced because the cordierite content was a predetermined ratio or more. On the other hand, the clay roof tile of Example 21 was poor Δ. This is thought to be because the linear thermal expansion coefficient of the glaze layer did not become sufficiently small because the cordierite content was below a predetermined ratio.

（ハイシルバー釉薬を表面に施釉した粘土瓦）
従来用いられているハイシルバー釉薬を表面に、実施例の粘土瓦用釉薬を裏面に施釉した粘土瓦について説明する。実施例２５〜実施例５０の粘土瓦用釉薬を、表４に示す組成成分、含有率が異なる以外は、実施例１の粘土瓦用釉薬と同様に調製した。また、比較例４の粘土瓦用釉薬を、ゼーゲル式にて、Ｎａ_２Ｏが０．１１モル、Ｋ_２Ｏが０．１７モル、ＭｇＯが０．０６モル、ＣａＯが０．６５モル、ＭｎＯが０．０１モル、Ａｌ_２Ｏ_３が０．１７モル、Ｆｅ_２Ｏ_３が０．０２モル、ＳｉＯ_２が２．３４モル、ＴｉＯ_２が０．０３モル、Ｂ_２Ｏ_３が０．５５モル、Ｃｒ_２Ｏ_３が０．０２モル、の割合になるように、原料を適宜配合し調製した。この粘土瓦用釉薬と水と糊剤とをミルに投入し、混合して実施例２５〜実施例５０、比較例４の釉薬泥漿を得た。なお、比較例４の粘土瓦用釉薬は、ハイシルバー釉薬である。また、表４中α−アルミナ、ジルコン、ペタライト、スポジューメンの「−」は、配合しないことを示す。また、比較例４のゼーゲル式の「−」は、上述したため表中には記載しないことを示す。また、比較例４の曲げ破壊強度の「−」は、比較対象であることを示す。 (Clay tile with high silver glaze on the surface)
Description will be made on a clay roof tile in which a conventionally used high silver glaze is applied on the front surface and the clay roof glaze of the embodiment is applied on the back surface. The clay roof glazes of Examples 25 to 50 were prepared in the same manner as the clay roof glaze of Example 1 except that the compositional components and contents shown in Table 4 were different. Moreover, the glaze for clay roofs of Comparative Example 4 was obtained by the Zegel formula, wherein Na ₂ O was 0.11 mol, K ₂ O was 0.17 mol, MgO was 0.06 mol, CaO was 0.65 mol, MnO Is 0.01 mol, Al ₂ O ₃ is 0.17 mol, Fe ₂ O ₃ is 0.02 mol, SiO ₂ is 2.34 mol, TiO ₂ is 0.03 mol, and B ₂ O ₃ is 0.55. The raw materials were appropriately blended and prepared so that the molar ratio of Cr ₂ O ₃ was 0.02 mol. The glaze for clay roof tile, water and paste were put into a mill and mixed to obtain glaze sludges of Examples 25 to 50 and Comparative Example 4. In addition, the glaze for clay tiles of the comparative example 4 is a high silver glaze. Moreover, in Table 4, “-” of α-alumina, zircon, petalite, and spodomen indicates that they are not blended. Further, the “−” in the Zegel formula of Comparative Example 4 indicates that it is not described in the table because it has been described above. In addition, “−” in the bending fracture strength of Comparative Example 4 indicates that it is a comparison target.

つぎに、粘土を主原料とする原料を混練し、実施例１と同様の瓦の形状になるように素地層を成形した。焼成後の１枚当りの瓦の質量は、２．４０Ｋｇとした。素地層の表面に比較例４の釉薬泥漿を施釉し、裏面に実施例２５の釉薬泥漿を施釉し、実施例２５の粘土瓦を得た。実施例２５の粘土瓦と同様に、素地層の表面に比較例４の釉薬泥漿を施釉し、裏面に実施例２６〜実施例５０の釉薬泥漿をそれぞれ施釉し、実施例２６〜実施例５０の粘土瓦をそれぞれ得た。また、素地層の表面および裏面に比較例４の釉薬泥漿を施釉し、比較例４の粘土瓦を得た。実施例２５〜実施例５０、比較例４の釉薬釉薬泥漿の施釉量は、実施例１と同様である。
つぎに、実施例２５〜実施例５０、比較例４の粘土瓦をトンネル炉で酸化焼成した。焼成温度、焼成時間は、実施例１と同様である。焼成工程の後、実施例２５〜実施例５０、比較例４の粘土瓦の焼成品が得られた。 Next, a raw material mainly composed of clay was kneaded, and a base layer was formed so as to have the same tile shape as in Example 1. The mass of the tile per sheet after firing was 2.40 kg. The glaze slurry of Comparative Example 4 was applied to the surface of the base layer, and the glaze slurry of Example 25 was applied to the back surface to obtain the clay roof tile of Example 25. As with the clay roof tile of Example 25, the glaze slurry of Comparative Example 4 was applied to the surface of the base layer, and the glaze slurry of Examples 26 to 50 was applied to the back surface, respectively. Each clay tile was obtained. Moreover, the glaze slurry of Comparative Example 4 was applied to the front and back surfaces of the base layer to obtain the clay roof tile of Comparative Example 4. The amount of glaze of glaze glaze slurry of Examples 25 to 50 and Comparative Example 4 is the same as that of Example 1.
Next, the clay roof tiles of Examples 25 to 50 and Comparative Example 4 were oxidized and fired in a tunnel furnace. The firing temperature and firing time are the same as in Example 1. After the firing step, fired products of the clay roofs of Examples 25 to 50 and Comparative Example 4 were obtained.

［釉薬の色調］
焼成後の実施例２５〜実施例５０、比較例４の粘土瓦の目付け部分の裏面の釉薬色調と裏面の釉薬色調との違いを実施例１と同様の評価基準で目視検査した。 [Color tone of glaze]
The difference between the glaze color tone on the back surface and the glaze color tone on the back surface of the clay tiles of Example 25 to Example 50 and Comparative Example 4 after firing was visually inspected according to the same evaluation criteria as in Example 1.

［曲げ破壊強度］
焼成後の実施例２５〜実施例５０、比較例４の粘土瓦の曲げ破壊強度を実施例１と同様に測定した。測定結果を比較例４と比較して、曲げ破壊荷重が１７３％以上（３０００Ｎ以上）であるものを優良◎（◎印）、曲げ破壊荷重が１５０％以上（２６００Ｎ以上）１７３％未満であるものを良好○（○印）、曲げ破壊荷重が１５０％未満であるものを不良△（△印）とした。 [Bending fracture strength]
The bending fracture strength of the clay roofs of Examples 25 to 50 and Comparative Example 4 after firing were measured in the same manner as in Example 1. Compared with Comparative Example 4, the measurement results are excellent when the bending fracture load is 173% or more (3000N or more), and the bending fracture load is 150% or more (2600N or more) less than 173% Is a good ◯ (◯ mark), and the one having a bending fracture load of less than 150% is defined as a defective Δ (Δ mark).

表４に示すように、釉薬の色調は、実施例２５〜実施例５０の粘土瓦で良好○であった。これは、α−アルミナ、ジルコン、ペタライト、スポジューメンの含有率が所定割合以下であったため、釉薬の色調の変化が少なかったためと考えられる。
また、曲げ破壊強度は、実施例２５、実施例３３、実施例３５、実施例３８〜４０、実施例４２、実施例４３の粘土瓦で優良◎であり、実施例２６〜２８、実施例３２、実施例３４、実施例３６、実施例３７、実施例４１、実施例４６、実施例４７、実施例４９の粘土瓦で良好○であった。これは、ＳｉＯ_２の含有率が所定割合以上であったため、釉薬層の軟化温度が大きくなったためと考えられる。一方、実施例２９〜３１、実施例４４、実施例４５、実施例４８、実施例５０の粘土瓦は不良△であった。これは、ゼーゲル式で表されたＫ_２Ｏ、ＣａＯの含有率が少ない又は多かったため、または、ジルコン、ペタライト、スポジューメンの含有率が所定割合以上であったためと考えられる。 As shown in Table 4, the color tone of the glaze was good with the clay roof tiles of Examples 25 to 50. This is presumably because the change in the color tone of the glaze was small because the contents of α-alumina, zircon, petalite, and spodumene were less than a predetermined ratio.
Moreover, the bending fracture strength is excellent in the clay roofs of Example 25, Example 33, Example 35, Examples 38 to 40, Example 42, and Example 43, and Examples 26 to 28 and Example 32. The clay roof tiles of Example 34, Example 36, Example 37, Example 41, Example 46, Example 47, and Example 49 were good. This is presumably because the softening temperature of the glaze layer was increased because the content of SiO ₂ was a predetermined ratio or more. On the other hand, the clay roof tiles of Examples 29 to 31, Example 44, Example 45, Example 48, and Example 50 were defective Δ. This is presumably because the content of K ₂ O and CaO expressed by the Seegel formula was low or high, or the content of zircon, petalite and spodumene was a predetermined ratio or more.

１０粘土瓦
２０素地層
３０第１の釉薬層
４０第２の釉薬層
１００台
１１０Ａ、１１０Ｂ、１１０Ｃ丸棒 10 clay roof tile 20 base layer 30 first glaze layer 40 second glaze layer 100 units 110A, 110B, 110C round bar

Claims

A base layer composed of clay, a first glaze layer disposed on the back surface of the base layer, a second glaze layer disposed on the surface of the base layer,
Clay tiles characterized by comprising.

The glaze constituting the first glaze layer is α-alumina (Al ₂ O ₃ ), zircon (ZrO ₂ SiO ₂ ), spodumene (Li ₂ OAl ₂ O ₃ 4SiO ₂ ), petalite (Li ₂ OAl ₂ O _3). 8SiO ₂ ), cordierite (2MgO ₂ Al ₂ O ₃ 5SiO ₂ ), or one or more materials selected from the group consisting of:
The clay roof tile according to claim 1, wherein:

The glaze that constitutes the first glaze layer contains 4% by mass to 5% by mass cordierite, 2% by mass to 3% by mass α-alumina, or 1% by mass to 2% by mass zircon. ,
In the Segel formula,
Na ₂ O 0.01 mol, K ₂ O 0.01 mol, MgO 0.05 mol, CaO 0.18 mol, MnO 0.76 mol,
Al ₂ O ₃ is 0.16 mol, Fe ₂ O ₃ is 0.03 mol, B ₂ O ₃ is 0.08 mol,
SiO ₂ is 1.33 mol, TiO ₂ is 0.22 mol, ZrO ₂ is 0.31 mol,
The clay roof tile according to claim 1, wherein the clay roof tile has a composition expressed as:

The glaze constituting the first glaze layer contains 2% by mass to 6% by mass of cordierite, or 2% by mass of petalite,
In the Segel formula,
Na ₂ O 0.01 mol, K ₂ O 0.01 mol, Li ₂ O 0.21 mol, MgO 0.67 mol, CaO 0.02 mol, MnO 0.08 mol,
Al ₂ O ₃ is 0.67 mol, Fe ₂ O ₃ is 0.05 mol,
SiO ₂ is 3.08 mol, TiO ₂ is 1.01 mol, ZrO ₂ is 0.63 moles,
The clay roof tile according to claim 1, wherein the clay roof tile has a composition expressed as:

The glaze constituting the first glaze layer contains 4% by mass or more and 6% by mass or less cordierite,
In the Segel formula,
Na ₂ O 0.01 mol, K ₂ O 0.01 mol, MgO 0.02 mol, CaO 0.07 mol, MnO 0.80 mol, BaO 0.09 mol,
Al ₂ O ₃ is 0.27 mol, Fe ₂ O ₃ is 0.02 mol,
SiO ₂ is 1.66 mol, TiO ₂ is 0.19 mol, ZrO ₂ is _0.13, B 2 _{O 3} is 0.04 mol,
The clay roof tile according to claim 1, wherein the clay roof tile has a composition expressed as:

The glaze constituting the first glaze layer is
In the Segel formula,
Na ₂ O more than 0.00 mol 0.03 mol or less, K ₂ O more than 0.00 mol 0.01 mol or less, CaO 0.02 mol, Li ₂ O 0.96 mol or more and 0.99 mol Less than,
Al ₂ O ₃ is 1.00 mol or more and 2.00 mol or less,
SiO ₂ is 6.31 mol or more and 8.31 mol or less,
The clay roof tile according to claim 1, wherein the clay roof tile has a composition expressed as:

The glaze constituting the first glaze layer is
1% by weight or more and 7% by weight or less α-alumina, 1% by weight or more and 2% by weight or less zircon, 1% by weight or more and less than 100% by weight petalite, or 1% by weight or more and less than 20% by weight spodumene,
The clay roof tile according to claim 1 or 2, wherein