Lead- and boron-free matte black color-based glaze for roof tile

Abstract

To provide a matte black color-based glaze for roof tile that does not practically contain boron.SOLUTION: Disclosed is a matte black color-based glaze for roof tile including the followings. (1) In Seger expression, MgO:0-0.25 mol, CaO:0.25-0.8 mol, BaO and / or SrO:0.1-0.55 mol, R2O and / or ZnO:≤0.25 mol, (R2O shows one or more kinds of Li2O, Na2O, and K2O); SiO2:1.5-3.5 mol, B2O3:0-0.05 mol, ZrO2:0-0.25 mol, and Al2O3:0.2-0.65 mol, (2) by wt.% to the whole glaze, MnO≥2.5, Fe2O3≤9, and Cr2O3≤4.5.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a boron-free glaze for a matte black roofing tile, that is, a glaze for a matte black roofing tile that is at least substantially free of boron. [Background technology]

[0002] Matte black, along with silver, is a representative color for ceramic tiles that suits the Japanese climate. Because tiles that are darker than the wall are often used, silver and black are used extremely frequently.

[0003] Traditionally, lead was used as a melting material in the glaze for matte black roofing tiles, but lead-free glazes were developed to eliminate pollution problems and improve the working environment. To ensure meltability in low and medium temperature firing ranges, B2O3 is used as a substitute for lead.

[0004] Alkali metals (Li2O, Na2O, and KO) are also candidates for melting materials, but their large thermal expansion increases the risk of cracking. Crazing must be suppressed to maintain performance and aesthetics, and to prevent discoloration and cracking, matte glazes for roofing tiles are made in the alumina matte range rather than the alkali matte range (Patent Document 1). However, alumina matte has a lower SiO2 / Al2O3 ratio, which means that the reactivity of the glaze is poorer than that of glossy glaze (i.e., it has high fire resistance and is difficult to melt). Therefore, the current situation is that we must rely on B2O3 as a melting agent.

[0005] Patent Document 2 describes B2O3 and R 1 The publication describes a method for producing a Pb-free glaze, which includes a step of producing a glossy glaze without using PbO, using an amount of 2O less than a predetermined standard amount and an amount of alkaline earth elements greater than the predetermined standard amount, and a glaze for low-temperature fired roofing tiles produced by the method. However, the publication only discloses technology related to glossy roofing tiles.

[0006] Furthermore, Patent Document 3 discloses a glaze used for black roofing tiles, but this glaze also requires 0.05 to 0.2 mol of B2O3.

[0007] As described above, B2O3 is considered to be an essential component in the glaze of black tiles, including matte black tiles. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 58-88141 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-173762 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-180082 Summary of the Invention [Problem to be solved by the invention]

[0009] In recent years, from the viewpoints of occupational health and environmental safety, there has been a demand for boron-free glazes, even for matte black glazes. However, the development and provision of such glazes has not yet even begun. [Means for solving the problem]

[0010] In view of the above problems, the present inventors have investigated the possibility of obtaining a matte black glaze that does not use boron at least substantially, and have found that the above problems may be solved by adjusting specific components. They have then pursued further research and have completed the present invention.

[0011] That is, the present invention relates to at least the following inventions: [1] Matte black roofing glazes, including: (1) In the Segel representation, MgO: 0 to 0.25 mol CaO: 0.25 to 0.8 mol BaO and / or SrO: 0.1 to 0.55 mol R2O and / or ZnO ≦0.25 moles (R2O represents one or more of Li2O, Na2O, and K2O); SiO2: 1.5 to 3.5 mol B2O3: 0 to 0.05 mol ZrO2: 0 to 0.25 mol, and Al2O3: 0.2 to 0.65 mol (2) Expressed in weight percent relative to the total glaze, MnO≧2.5 Fe2O3≦9, and Cr2O3≦4.5. [2] B2O3: 0 to 0.025 mol of glaze [1]. [3] A glaze that does not contain B2O3[2]. [4] (i) The amount of Fe2O3 is 4% or more by weight of the total glaze; (ii) the amount of Fe2O3 is 1% or more but less than 3% by weight of the total glaze, and the amount of B2O3 is 0 mol to 0.03 mol; or (iii) The amount of Fe2O3 is 3% or more but less than 4% by weight of the total glaze, and the amount of MnO is 6% or more by weight of the total glaze; A glaze selected from [1] to [3]. [5] (i') The amount of Fe2O3 is 5% or more by weight relative to the total weight of the glaze, and the amount of MnO is 6-8% by weight relative to the total weight of the glaze, or (iii') The glaze of [4], in which the amount of Fe2O3 is 3% or more but less than 4% by weight of the whole glaze, and the amount of MnO is 10% or more by weight of the whole glaze. [6] [4] A glaze in which the amount of Fe2O3 is 3% or more but less than 4% by weight of the entire glaze, the amount of MnO is 7% or more by weight of the entire glaze, and Co3O4 is contained in an amount of 0 to 0.15% by weight of the entire glaze. [7] The glaze of any one of [1] to [6] further containing TiO2 and / or P2O5. [8] A glaze of any of [1] to [7] containing ZnO and further containing Co3O4. [9] Any of the glazes [1] to [7], which are glazes with the composition shown in the table below: [Table 1-1] [Table 1-2]

[10] Matte black tiles manufactured using any of the glazes [1] to [9]. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a matte black glaze that does not contain boron (and does not contain lead), thereby achieving further improvements in occupational health and environmental safety when producing matte black glazes and matte black roofing tiles. The matte black glaze of the present invention exhibits the particularly remarkable effect of being able to fully develop a matte black color despite not containing boron.

[0013] Furthermore, the present invention not only succeeds in avoiding the use of boron in matte black glazes, but also differs significantly from the prior art in that it uses specific amounts of components such as R2O, Al2O3, MnO, and TiO2, and allows the use of a larger amount of CaO, a component that poses no significant problems in terms of hygiene and environmental safety. Considering that CaO poses no significant problems in terms of hygiene and environmental safety as described above, this is a special effect that even a person skilled in the art would not have anticipated from the prior art.

[0014] Without wishing to be bound by theory, it is possible that the desired effect of the glaze of the present invention is the result of the brilliant discovery of a synergistic effect due to the following composition: (1) Lowering SiO2·Al2O3 (2) Set a lower limit for the amount of MnO (2.5% by weight or more), which is expected to have an effect not only as a coloring agent but also as a melting agent. (3) Conversely, the addition of Fe2O3·Cr2O3 (meaning Fe2O3 and / or Cr2O3; the same applies hereinafter), which increases the refractoriness, should be limited or adjusted by an upper limit depending on the amount of MnO.

[0015] (a) Among the glazes of the present invention, those containing ZrO2 have the effect of suppressing thermal expansion of the glaze, which may occur due to the low proportion of SiO2·Al2O3, by the ZrO2. (b) Among the glazes of the present invention, those containing R2O (and / or P2O5) to an extent that does not cause crazing can achieve a wider range of desired physical properties by using R2O (and / or P2O5). (c) Among the glazes of the present invention, those containing small amounts of ZnO and TiO2 can give the roofing tiles a more distinct black color. In other words, small amounts of ZnO and TiO2 have the effect of accelerating the melting of the glaze. (d) In the glaze of the present invention, BaO and SrO can be partially substituted for each other, making it possible to achieve a wider range of desired physical properties. (e) Among the glazes of the present invention, in the glazes (zinc glazes) containing about 0.1 mol of ZnO, a black color modified from brown can be obtained by adding Co·Ni (rare metals) or the like. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described in further detail below. The amount of each component is expressed in moles in Segel notation unless otherwise specified. The amount or range of the amount of each component specified in this specification or the present invention may be modified by a range of about 5% as long as the desired effect of the present invention is achieved.

[0017] The glaze of the present invention is a matte black roofing glaze that is at least substantially free of boron. However, without boron, the glaze melts poorly, its fire resistance increases, and crystallization of the components that produce the black color (mainly MnO and Fe2O3·Cr2O3) becomes difficult to form. As a result, undesirable phenomena such as poor color development and foaming may occur. It has been discovered for the first time in the present invention that using specific amounts of components such as SiO2, Al2O3, MnO, and Fe2O3·Cr2O3 and adjusting the amount of CaO is effective in suppressing these undesirable phenomena, particularly poor color development. In other words, it has been revealed for the first time in the present invention that using specific amounts of components such as SiO2, Al2O3, MnO, and Fe2O3·Cr2O3 and using CaO in an amount that may be greater than the amount used in the prior art tends to suppress the above undesirable phenomena.

[0018] The glaze of the present invention may or may not contain B2O3, and if it does contain B2O3, the amount is 0.05 mol or less. The preferred amount of B2O3 in the glaze of the present invention is 0.025 mol or less. More preferably, the glaze of the present invention does not contain B2O3.

[0019] The glaze of the present invention contains SiO2 in an amount of 1.5 to 3.5 mol, preferably 1.8 to 3.2 mol, and more preferably 2.0 to 3.0 mol.

[0020] The glaze of the present invention contains Al2O3 in an amount of 0.2 to 0.65 mol. By using Al2O3 in this amount, not only is black coloring achieved, but the condition of the glaze surface can also be improved. The amount of Al2O3 is preferably 0.3 mol to 0.6 mol, and more preferably 0.4 to 0.5 mol.

[0021] The glaze of the present invention contains 2.5% or more MnO expressed as % by weight based on the total weight of the glaze. The amount of MnO is preferably 3.0% or more, and more preferably 3.0 to 10%. These preferred amounts may be determined by adjusting the amounts of other components.

[0022] The glaze of the present invention contains Fe2O3 in an amount of Fe2O3≦9, expressed as % by weight based on the total glaze. In the glaze of the present invention, the amount of Fe2O3 is preferably 8% or less, and is also preferably 4% or more. In the glaze of the present invention, the amount of Fe2O3 is preferably 1% or more and less than 3%, because this makes it easier to reduce the amount of B2O3. When the amount of Fe2O3 is 1% or more and less than 3%, the glaze of the present invention is preferably one in which the amount of B2O3 is 0 mol to 0.03 mol. In the glaze of the present invention, when the amount of Fe2O3 is 3% or more and less than 4%, it is preferable that the amount of MnO is 6% or more. Among the above glazes of the present invention, (i') The amount of Fe2O3 is 5% or more by weight relative to the total weight of the glaze, and the amount of MnO is 6-8% by weight relative to the total weight of the glaze, or (iii') The amount of Fe2O3 is 3% or more and less than 4% by weight of the whole glaze, and the amount of MnO is 10% or more by weight of the whole glaze. Glaze is particularly preferable as it produces a black color. In the glaze of the present invention, when the amount of Fe2O3 is 3% or more and less than 4% by weight of the entire glaze and the amount of MnO is 7% or more by weight of the entire glaze, a glaze containing Co3O4 in an amount of 0 to 0.15% by weight of the entire glaze is preferred.

[0023] The glaze of the present invention contains Cr2O3 in an amount of Cr2O3≦4.5, expressed as % by weight based on the total glaze. In the glaze of the present invention, an amount of Cr2O3≦4% is preferred.

[0024] Other components contained in the matte black glaze of the present invention will be described below. (a) The glaze of the present invention may contain ZrO2, which can suppress the thermal expansion of the glaze that may occur due to the low proportion of SiO2·Al2O3. The amount of ZrO2 in the glaze of the present invention is 0 to 0.25 mol. In the glaze of the present invention, the amount of ZrO2 is preferably 0 to 0.25 mol.

[0025] (b) Among the glazes of the present invention, those containing R2O (and / or P2O5) can achieve a wider range of desired physical properties without causing crazing by using R2O (and / or P2O5), where R2O represents one or more of Li2O, Na2O, and K2O. The amount of R2O in the glaze of the present invention is ≦0.25 mol, preferably ≦0.2 mol, provided that the total amount with ZnO does not exceed 0.25 mol.

[0026] The glaze of the present invention may contain P2O5, and the amount of P2O5 is, for example, 0.1 to 3% by weight based on the total weight of the glaze, and preferably 0.5 to 2%.

[0027] (c) In the glaze of the present invention, R2O may be replaced by ZnO, and glazes of the present invention containing a small amount of ZnO can give the roofing tiles a more distinct black color. Therefore, zinc can compensate for the effect of assisting the melting of boron. The amount of ZnO in the glaze of the present invention is ≦0.25 mol, with the total amount with R2O not exceeding 0.25 mol, and an amount of ≦0.2 mol is preferred.

[0028] (e) Among the glazes of the present invention, in the glaze containing ZnO (zinc glaze), a black color modified from brown can be obtained by adding Co·Ni (rare metals) or the like. In the glaze of the present invention, TiO2 may be used, and TiO2 may be used in combination with ZnO. The amount of TiO2 used is, for example, 0.1 to 3% of the total glaze, and preferably 0.5 to 2%.

[0029] (d) The glaze of the present invention contains BaO or SrO, which can be partially substituted for each other. These components allow a wider range of desired physical properties to be achieved. The amount of BaO and / or SrO is 0.1 to 0.55 moles each, and the total amount does not exceed 0.55 moles. In the glaze of the present invention, the amount of BaO and / or SrO is preferably 0.2 to 0.5 mol, more preferably 0.3 to 0.4 mol.

[0030] In the glaze of the present invention, a black pigment may be used as appropriate. The amount of the black pigment is not limited and may be determined depending on the degree of black color development. The amount of the black pigment is, for example, 1% to 5% of the total amount of the glaze.

[0031] The matte black glaze of the present invention can be produced by conventional methods. For example, a mixture of the desired composition may be prepared using raw materials such as silica stone, kaolin, gyome clay, manganese oxide, and iron oxide. Furthermore, an appropriate amount of additives such as CMC and bentonite may be added to the mixture, and the mixture may be wet-pulverized in a pot mill or the like to obtain the final product.

[0032] The present invention also relates to a matte black roofing tile produced using any of the above-mentioned matte black glazes, which can be produced by a method commonly used in the art. Specifically, the tile can be fired at a temperature of about 1100°C to about 1160°C, and the glaze coating weight can be 50g to 90g per Japanese-style shingle roofing tile. Furthermore, the matte black glaze of the present invention may contain components other than those described above as components that are inevitably mixed in during the manufacturing process of the matte black glaze, provided that the object of the present invention is not impaired. [Example]

[0033] The present invention will be described in more detail below with reference to specific examples, which are not intended to limit the present invention in any way.

[0034] [Test method] Mixtures with the compositions shown in Table 1 were prepared using raw materials such as silica, kaolin, frog's eye clay, manganese oxide, and iron oxide, to which 0.5 parts each of CMC and bentonite was added, and the mixture was wet-ground in a pot mill. The glaze was applied to a coating weight of 60 to 80 g per Japanese-style shingle tile, and each tile was fired at the temperatures shown in Table 1 to obtain tiles. The temperatures were set to take into account the composition of each glaze and to ensure the most appropriate black color development and glaze surface condition.

[0035] The color development of the resulting tiles was judged by visual observation. When the desired black color development was observed, it was rated as "good," and in other cases the observed color was recorded. The state of the glaze surface was also visually inspected to determine the degree of melting of the glaze. If the glaze was sufficiently melted, no mark was made, and if it was not melted enough, it was marked as "insufficiently melted."

[0036] [result] The results are shown in Tables 2-1 and 2-2 (the base glaze is in molar ratio, and the colorants (MnO, Fe2O3, and Cr2O3) and other additives are in weight % relative to the total weight of the glaze. Integers from 1 to 10 indicate the example numbers.) The black pigment used in Example 7 is a black pigment that is not thought to have a significant effect on the melting of the glaze of the present invention. [Table 2-1] [Table 2-2]

[0037] [Table 3]

[0038] All of the glazes of the present invention (Examples 1 to 10) developed a black color (Tables 2-1 and 2-2). In contrast, Comparative Examples 1 to 8 are examples in which the amounts indicated in bold in the table were outside the range required for the glaze of the present invention, and in all of these cases the color of the tiles did not turn black or the glaze did not function properly due to insufficient melting (Table 3). Among Examples 1 to 10, the glaze surface condition was particularly good in Examples 1 and 2. Therefore, among the glazes of the present invention, those in which the amount of Fe2O3 is 5% or more by weight relative to the total weight of the glaze and the amount of MnO is 6 to 8% by weight relative to the total weight of the glaze, and those in which the amount of Fe2O3 is 3% or more but less than 4% by weight relative to the total weight of the glaze and the amount of MnO is 10% or more by weight relative to the total weight of the glaze, were considered to have particularly excellent effects. [Industrial Applicability]

[0039] The method of the present invention makes it possible to provide a matte black roofing roof tile glaze that is substantially free of boron, and therefore the present invention will greatly contribute to the development of the glaze manufacturing industry, the matte black roofing roof tile manufacturing industry, and related industries.

Claims

1. Matte black roofing glazes, including: (1) In Segel representation, MgO: 0 to 0.25 mol CaO: 0.25 to 0.8 mol BaO and / or SrO: 0.1 to 0.55 mol R ２ O and / or ZnO ≦0.25 mol (R ２ O is Li ２ O, Na ２ O and K ２ O); SiO ２ : 1.5 to 3.5 mol B ２ O ３ : 0 to 0.05 mol ZrO ２ : 0 to 0.25 moles, and Al ２ O ３ : 0.2 to 0.65 mol (2) Expressed in weight percent relative to the total glaze, MnO≧2.5 Fe ２ O ３ ≦9, and Cr ２ O ３ ≦4.5。

2. B ２ O ３ : 0 to 0.025 mol of the glaze according to claim 1.

3. B ２ O ３ The glaze according to claim 2, which does not contain

4. (i) Fe ２ O ３ The amount of is 4% or more by weight of the total glaze; (ii) Fe ２ O ３ The amount of is 1% or more and less than 3% by weight of the entire glaze, and B ２ O ３ or (iii) Fe ２ O ３ The amount of is 3% or more and less than 4% by weight of the entire glaze, and the amount of MnO is 6% or more by weight of the entire glaze, The glaze of claim 1 ,

5. (i') Fe ２ O ３ The amount of is 5% or more by weight based on the total weight of the glaze, and the amount of MnO is 6 to 8% by weight based on the total weight of the glaze, or (iii') Fe ２ O ３ The amount of is 3% or more and less than 4% by weight based on the total weight of the glaze, and the amount of MnO is 10% or more by weight based on the total weight of the glaze, The glaze according to claim 4.

6. Fe ２ O ３ The amount of MnO is 3% or more and less than 4% by weight based on the total weight of the glaze, and the amount of Co is 7% or more by weight based on the total weight of the glaze. ３ O ４ The glaze according to claim 4, comprising an amount of 0 to 0.15% by weight based on the weight of the entire glaze.

7. TiO ２ and / or P ２ O ５ The glaze of claim 1 further comprising:

8. Contains ZnO, Co ３ O ４ The glaze of claim 1 further comprising:

9. The glaze according to claim 1, which is any glaze having the composition shown in the table below (the base glaze has a molar ratio of 0.01 to 0.01, and the coloring agent (MnO, Fe) is 0.01 to 0.01). ２ O ３ and Cr ２ O ３ ) and other additives (wt%) based on the total weight of the glaze: 【Table 1-1】 【Table 1-2】

10. A matte black roofing tile manufactured using the glaze according to any one of claims 1 to 9.

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