JP6197445B2 - Enamel article and manufacturing method thereof - Google Patents

Description

  The present invention relates to an enamel article using cast iron as a base material and forming a glaze layer on the cast iron.

  Enamel articles having a glaze layer formed on the surface of a metal material are widely distributed in the market as water-based products such as bathtubs, washbasins, hand-washers, and sinks. In addition, there is a demand for luxury-oriented customers in the field of water-based products, preferably large-sized water-based products (for example, bath tubs) that combine the strength of metal and the quality of glass. Steel plates and castings are widely known as base materials for enamel articles, and dry methods and wet methods are known as methods for applying glaze to the base materials. Furthermore, bubbles are generated due to the components contained in the substrate by heating, and it has been necessary to control the bubbles so as not to adversely affect the appearance of the enamel article. This consideration for bubbles was considered to be particularly necessary in cast iron.

  Japanese Patent Application Laid-Open No. 1-219040 (Patent Document 1) describes that the action of carbon dioxide gas and hydrogen gas, which cause bubbles generated in the enamel layer, is suppressed. This document describes reducing the amount of carbon contained in the base material in order to suppress the generation of carbon dioxide gas, and applying metal plating to the surface of the base material in order to suppress the generation of hydrogen gas. Has been.

  Further, in JP-A-3-150371 (Patent Document 2), when iron is used as a base material, carbon contained in the iron and water in the glaze react to generate hydrogen gas or carbon dioxide gas, It is described that bubbles occur in the glaze layer or on the surface. And since this bubble breaks or remains as a pinhole, it is said that the smoothness of the surface is impaired. In this patent document, iron is preheated to a temperature higher than the softening start temperature of the glaze, and spraying the glaze on the iron can suppress the influence of bubbles.

Japanese Patent Laid-Open No. 1-219040 Japanese Patent Laid-Open No. 3-150371

  When a casting is used as a base material, a large amount of carbon is contained in the casting, so that the amount of bubbles generated from the casting is large. Therefore, in order to suppress the adverse effect of the bubbles on the glaze layer, the thickness of the glaze layer of about 1.0 to 2.0 mm is required. On the other hand, when a steel plate is used as the base material, it is difficult to be affected by bubbles because the carbon content is small. However, the steel plate is not preferable as a water product because it is thin and lacks a profound feeling as a hollow article.

  When a casting is used as the base material, if the glaze is applied by a dry method, the thickness of the glaze layer becomes 1.2 to 2.0 mm, which is restricted in terms of design. On the other hand, when glaze is applied by a wet method, it is possible to form a thin glaze layer, but there is a problem that bubbles affect the adhesion between the glaze layer and the substrate and the appearance of the glaze layer surface.

  The present inventors can suppress the influence of bubbles on the surface of the glaze layer of the enamel article by controlling the distribution state of the bubbles in the glaze layer even when a casting is used as the base material. And gained knowledge. Moreover, the knowledge that the influence of the bubble in the interface of the base material of a hollow article and a glaze layer can be suppressed was acquired. The present invention is based on such knowledge.

  Accordingly, an object of the present invention is to provide an enamel article having good adhesion between the base material and the glaze layer and a good appearance.

  The enamel article according to the present invention is an enamel article in which a glaze layer is formed on a base material, the base material is cast iron, and the glaze layer is formed with a thickness of the glaze layer from the surface of the base material. The ratio between the area of bubbles contained in the former and the area of bubbles contained in the latter when the substrate is divided into the substrate side region and the surface side region of the glaze layer by an intermediate line at half the position. Is 0: 100 or more and 40:60 or less.

  According to one aspect of the present invention, in the enamel article according to the present invention, the thickness of the glaze layer is from 0.1 mm to 1.0 mm.

  According to one aspect of the present invention, in the enamel article according to the present invention, the thickness of the glaze layer is 0.2 mm or more, and the area from the substrate surface to the surface of the glaze layer is 0.1 mm. The ratio of the area of the bubble contained is 35% or less with respect to the area of the bubble contained in the whole glaze layer.

According to one aspect of the present invention, in the enamel article according to the present invention, the composition after firing in the region from the substrate surface to the surface of the glaze layer up to 0.05 mm is SiO ₂ > 55% by weight.

According to one aspect of the present invention, the enamel article according to the present invention has a ratio of the area of undissolved SiO ₂ contained in a region from the base material surface to the surface direction of the glaze layer up to 0.05 mm. It is 15% to 70% with respect to the total area of the region.

  ADVANTAGE OF THE INVENTION According to this invention, the enamel article which has the favorable adhesiveness between a base material and a glaze layer and a favorable external appearance is realizable.

1 shows a laser micrograph of a specimen cut surface of an enamel article according to the present invention. Moreover, in this image, the reference line which showed the interface of a glaze layer and a base material with the line approximated by the straight line is shown. The micrograph for evaluating the presence or absence of the black defect in the glaze layer surface and the mode is shown. 1 shows a laser micrograph of a specimen cut surface of an enamel article according to the present invention. In addition, the lower layer is shown in this image. The backscattered electron image acquired with the scanning electron microscope (SEM) is shown (left end figure). In addition, the state of Si element and O element mapping obtained by analyzing the reflected electron image by EDX (energy dispersive X-ray spectroscopy) for measuring the amount of undissolved SiO ₂ contained in the lower layer is shown. Shown (center view, right end view).

Enamel article The enamel article according to the present invention is an enamel article in which a glaze layer is formed on a base material, and the base material is cast iron. Further, when the glaze layer is divided into an area on the base material side of the glaze layer and an area on the surface side of the glaze layer by an intermediate line located at half the thickness of the glaze layer from the base material surface, the former The ratio of the area of bubbles contained in the bubble to the area of bubbles contained in the latter is 0: 100 or more and 40:60 or less. By controlling the distribution state of the bubbles contained in the glaze layer in this way, it becomes possible to suppress the influence of bubbles on the surface of the enamel article, even when a casting is used as the base material, and an excellent appearance quality is achieved. Can be realized. Moreover, it becomes possible to suppress the influence of bubbles at the interface between the base material and the glaze layer, and excellent adhesion can be realized. A preferable range of the bubble area ratio is 10:90 or more and 40:60 or less.

Bubbles In the present invention, “bubbles” to be controlled include all bubbles actually contained in the glaze layer. For example, a gas such as carbon dioxide or hydrogen generated when a component (for example, carbon) contained in cast iron as a base material reacts with water or oxygen existing in the glaze layer and / or the outside during firing. However, it includes those that reach the glaze layer and become bubbles. This bubble is generated when, for example, a glaze layer is formed on a substrate, and is considered to exist in the glaze layer, but is generated by a mechanism other than that and reaches the glaze layer. Including.

  The area of bubbles contained in the glaze layer is calculated by the following method. That is, the mirror-polished cross section of the glaze layer is observed using a laser microscope (for example, an optical measuring device LEXTOLS4000, manufactured by OLYMPUS) to obtain an image. Using the image analysis software (for example, WINROOF ver6.5.1, manufactured by MITANI CORPORATION), the amount of bubbles contained in the glaze layer is measured. In the image, the recesses are made to be bubbles as compared with the substrate surface, and the recesses and the other portions are binarized. Then, the area of the bubble contained in a glaze layer is calculated by calculating the area of a recessed part.

Base enamel articles according substrates present invention is characterized in that it is cast iron. “Cast iron” means a casting mainly composed of iron (Fe), carbon (C), and silicon (Si). The cast iron is not particularly limited as long as the amount of each component contained in the cast iron and other compositions are not particularly limited as long as it is an Fe—C alloy containing iron as a main component and 2.14 to 6.67% carbon.

Glaze layer The enamel article according to the present invention has a glaze layer formed on a substrate. In the present invention, the glaze layer may be a single layer or a multilayer. When a glaze layer consists of multiple layers, it is preferable that a glaze layer contains the lower glaze layer formed on the cast iron which is a base material, and the upper glaze layer formed on the said lower glaze layer. The thickness of the glaze layer of the enamel article according to the present invention can be 0.1 mm or more and 1.0 mm or less. The thickness of the glaze layer is more preferably 0.2 mm or more and 0.6 mm or less.

  The thickness of the glaze layer is calculated by the following method. That is, using a laser microscope (for example, an optical measuring device LEXTOLS4000, manufactured by OLYMPUS), a mirror-polished cross section of the glaze layer is observed, and an image is acquired so that the base material and the glaze layer fit. A reference line that linearly approximates the interface between the glaze layer and the substrate in the acquired image is provided, and the minimum value of the vertical distance from the reference line to the surface of the glaze layer is defined as the thickness of the glaze layer.

  According to one aspect of the present invention, in the enamel article according to the present invention, the thickness of the glaze layer is 0.2 mm or more, and the area from the substrate surface to the surface of the glaze layer is 0.1 mm. The ratio of the area of bubbles included is 35% or less with respect to the area of bubbles included in the entire glaze layer. By reducing the amount of bubbles present near the interface between the base material and the glaze layer, it becomes possible to increase the contact area between the base material and the glaze layer, and to improve the adhesion between the base material and the glaze layer. it can. More preferably, the thickness ratio of the glaze layer is 0.2 mm or more, and the ratio of the area of the bubbles contained in the region from the substrate surface to 0.05 mm in the surface direction of the glaze layer is the entire glaze layer. 20% or less with respect to the area of the bubbles contained in. Here, the “region from the substrate surface to 0.1 mm (0.05 mm) in the surface direction of the glaze layer” means from 0.1 mm (0.05 mm) in the surface direction of the glaze layer from the reference line described above. Means an area.

In the enamel article according to the present invention, the adhesion between the base material and the glaze layer is preferably 150 g / cm ² or more, and more preferably 200 g / cm ² or more. Since the enamel article according to the present invention has a small amount of bubbles in the vicinity of the interface between the base material and the glaze layer, an enamel article having a high adhesion between the base material and the glaze layer can be obtained. This adhesion force can be measured as follows. That is, an adhesive (for example, manufactured by Bond E250 Konishi Co., Ltd.) is applied to the surface of the glaze layer of the enamel article and the base material surface on the opposite side. A jig with a hook is bonded to each adhesive application surface of the enamel article. At this time, each adhesive application surface of the enamel article is bonded to the adhesion surface of the jig with a hook having the same size as the adhesive application surface of the enamel article. After these are bonded, a pulling test is performed with an autograph (for example, AG-5000B, manufactured by Shimadzu Corporation). The pulling speed is adjusted as appropriate, and the force when the glaze layer and the substrate are peeled is defined as the adhesive strength of the enamel article.

Further, the enamel article according to the present invention has a composition after firing in a region from the substrate surface to the surface direction of the glaze layer to 0.05 mm in a range of SiO ₂ > 55 wt%, more preferably SiO ₂ > 60 wt%. Preferably there is. Here, the “region from the substrate surface to 0.05 mm in the surface direction of the glaze layer” means a region from 0.05 mm to the surface direction of the glaze layer from the reference line. By this region Si0 ₂ is contained relatively large in the above range, it is possible to leave many areas where SiO ₂ is present in undissolved state in the vicinity of the interface after firing. Here, “SiO _{2 in} an undissolved state” means granular SiO ₂ that maintains a solid state without being dissolved after firing.

Further, according to a preferred aspect of the present invention, the amount of undissolved SiO ₂ that is relatively present in the vicinity of the interface after firing is the surface of the glaze layer from the substrate surface in the enamel article according to the present invention. The ratio of the area of undissolved SiO ₂ contained in the region up to 0.05 mm in the direction is 15% to 70%, more preferably 30% to 60%, with respect to the total area of the region. .

As described above, by the Si0 ₂ is abundant in the region, it is possible to leave many areas where SiO ₂ is present in undissolved state in the vicinity of the interface after firing. Thereby, it is considered that the bubble distribution control of the glaze layer is performed as follows, but the present invention is not limited to this action mechanism.

It is considered that a space formed by undissolved SiO _{2 is} formed by leaving many regions where undissolved SiO ₂ exists in the vicinity of the interface after firing. It seems that bubbles generated in this space can be moved easily by their buoyancy and guided to the area on the surface side of the glaze layer rather than the area on the base material side of the glaze layer, so that bubbles do not accumulate near the interface. .

On the other hand, although the generated bubbles rise, there are a lot of undissolved SiO _{2 in the} region, so that the bubbles that have risen through the space formed in this region It appears that the particle size becomes smaller and the buoyancy becomes smaller. Thereby, it is considered that the bubble ascending speed gradually decreases and it is possible to finally prevent the bubbles from reaching the surface of the glaze layer. As a result, unevenness of the glaze layer surface due to bubbles can be prevented. The undissolved SiO ₂ preferably has a particle size of 1 to 50 μm from the viewpoint of enabling favorable trapping of bubbles.

According to a preferred embodiment of the present invention, the surface roughness of the glaze layer of the enamel article according to the present invention is 0 <Wd ≦ 60. By making such a surface roughness, it is possible to eliminate the feeling of irregularities on the surface of the glaze layer when touched. The surface roughness of the glaze layer is more preferably 0 <Wd ≦ 50. Here, the “Wd value” means a Wd value measured by a microwave scan (DOI, orange peel) measuring device manufactured by BYK Gardner (Germany). This apparatus is known as a method for optically measuring a bright / dark pattern of a wavelength on a sample surface like a human eye. In this microwave scan, a laser point light source irradiates laser light at an angle of 60 ° with respect to a normal to the sample surface, and a detector measures reflected light at the same angle opposite to the normal. This apparatus is capable of detecting the optical profile of the sample surface by measuring the brightness / darkness of the reflected light one by one at a predetermined interval by moving the laser point light source over the coated sample surface and scanning. The detected optical profile can be spectrally analyzed through a frequency filter to analyze the structure of the sample surface. The characteristic spectrum of this device is as follows.
du: wavelength 0.1 mm or less; Wa: wavelength 0.1-0.3 mm; Wb: wavelength 0.3-1 mm; Wc: wavelength 1-3 mm; Wd: wavelength 3-10 mm; Sw: wavelength 0.3-1 .2 mm; Lw: wavelength 1.2 to 12 mm; DOI: wavelength 0.3 mm or less

A preferred glaze layer of the enamel article according to the present invention is mainly composed of SiO ₂ , and as other components, Al ₂ O ₃ , B ₂ O ₃ , Na ₂ O, K ₂ O, Li ₂ O, CaO, ZnO, MgO. , BaO, CaF ₂ , Na ₂ SiF ₆ , K ₂ SiF ₆ , F ₂ , P ₂ O ₅ , TiO ₂ , Co ₃ O ₄ , NiO, MnO ₂ and ZrO or a combination thereof. It is a waste.

Further, the glaze layer of the enamel article according to the present invention preferably contains 30% by weight or more and 80% by weight or less of RO ₂ (R = Si), but in addition to this, R ₂ O (R = Na, K) is 0%. % By weight to 30% by weight, RO (R = Ca, Zn, Mg, Ba) 0 to 15% by weight, and R ₂ O ₃ (R = Al) 0 to 30% by weight It is more preferable. Here, in the present specification, R ₂ O (R = Na, K) means one or more oxides selected from the group consisting of Na ₂ O and K ₂ O, and RO (R = Ca, Zn, Mg, Ba) means one or more oxides selected from the group consisting of CaO, ZnO, MgO and BaO. Further, other components can be appropriately selected and included in the glaze layer.

  Hereinafter, an embodiment in which the glaze layer is a multilayer including a lower glaze layer formed on cast iron as a base material and an upper glaze layer formed on the lower glaze layer will be described.

According to one aspect of the present invention, an enamel article according to the present invention includes a lower glaze layer formed on a cast iron as a base material, and an upper glaze layer formed on the lower glaze layer. and the composition after firing in the region up to 0.05mm in the direction of the surface of the glaze layer from said substrate surface, _SiO 2> 55 wt%, more preferably _SiO 2> 60 wt%. By this region Si0 ₂ is contained relatively large in the above range, it is possible to leave many areas where SiO ₂ is present in undissolved state in the vicinity of the interface after firing. Further, according to a preferred aspect of the present invention, the amount of undissolved SiO ₂ that is relatively present in the vicinity of the interface after firing is the surface of the glaze layer from the substrate surface in the enamel article according to the present invention. The ratio of the area of undissolved SiO ₂ contained in the region up to 0.05 mm in the direction is 15% to 70%, more preferably 30% to 60%, with respect to the total area of the region. . By Si0 ₂ is abundant in the region, it can leave many areas where SiO ₂ is present in undissolved state in the vicinity of the interface after firing, thereby acting machine bubble distribution control of the glaze layer is made The introduction is as already explained.

Here, when the glaze layer includes a lower glaze layer formed on the cast iron as a base material and an upper glaze layer formed on the lower glaze layer, “0 in the surface direction of the glaze layer from the base material surface”. “Area up to .05 mm” includes the case where only the lower cocoon layer is present and the case where the lower cocoon layer and a part of the upper cocoon layer are present. When a large amount of undissolved SiO ₂ is contained in the lower cocoon layer, the surface of the lower cocoon layer, that is, the interface between the upper and lower cocoon layers may become rough. In such a case, the lower glaze layer and the upper glaze layer coexist in the region from the base material surface to the surface of the glaze layer up to 0.05 mm.

Undercoat layer In the present invention, the undercoat layer is specified by the following method. That is, using a laser microscope (for example, an optical measuring device LEXTOLS4000, manufactured by OLYMPUS), a mirror-polished cross section of the glaze layer is observed, and an image is acquired so that the base material and the glaze layer fit. In the acquired image, the black layer formed on the substrate is identified as the lower layer.

According to one aspect of the present invention, the lower stratum layer preferably contains 55 wt% or more and 80 wt% or less of RO ₂ (R = Si), and further contains 0 wt% of R ₂ O (R = K, Na). % To 20% by weight, RO (R = Ca, Zn, Mg, Ba) 0% to 15% by weight, and R ₂ O ₃ (R = Al) content 0% to 30% by weight Is more preferable. Even more preferably, RO ₂ (R═Si) is contained in an amount of 60 wt% to 80 wt%. By being in such a range, it is possible to leave many regions where undissolved SiO ₂ exists in the vicinity of the interface between the base material and the glaze layer after firing. The action mechanism of the bubble distribution control in the glaze layer by this is as already explained. The lower cocoon layer preferably contains a large amount of undissolved SiO ₂ , but the ratio is more preferably in the range of 15 to 70% by weight. An even more preferred range is 30 to 60% by weight. Moreover, the ratio of the area of the undissolved SiO ₂ contained in the region of 0.05 mm from the substrate surface to the boundary surface direction of the lower cocoon layer and the upper cocoon layer is 15% to the total area of the region. 70% is preferable, and 30% to 60% is more preferable. In addition, the undissolved SiO ₂ preferably has a particle size of 1 to 50 μm from the viewpoint of enabling good trapping of bubbles.

  The thickness of the lower collar layer is preferably 0.02 mm or more and 0.4 mm or less. By setting it as such thickness, even if it is a sharp shape, a glaze layer can be formed, without producing a crack. A more preferable thickness of the lower heel layer is 0.05 mm or more and 0.1 mm or less.

  The thickness of the lower collar layer is calculated by the following method. That is, using a laser microscope (for example, an optical measuring device LEXTOLS4000, manufactured by OLYMPUS), a mirror-polished cross section of the glaze layer is observed, and an image is acquired so that the base material and the glaze layer fit. The acquired image is divided into a base material, a lower collar layer, and an upper collar layer according to color. A reference line that linearly approximates the interface between the glaze layer and the base material is provided, and the minimum value of the vertical distance from the reference line to the interface between the lower glaze layer and the upper glaze layer is defined as the thickness of the lower glaze layer.

Upper collar layer In the present invention, the upper collar layer is specified by the following method. That is, using a laser microscope (for example, an optical measuring device LEXTOLS4000, manufactured by OLYMPUS), a mirror-polished cross section of the glaze layer is observed, and an image is acquired so that the base material and the glaze layer fit. In the acquired image, the layer formed on the lower collar layer identified as described above is identified as the upper collar layer.

According to one aspect of the present invention, the upper collar layer preferably has an RO ₂ (R = Si) amount of 30 wt% or more and 70 wt% or less, and further an R ₂ O (R = K, Na) amount. Is 5 wt% or more and 30 wt% or less, RO (R = Ca, Zn, Mg, Ba) amount is 0 wt% or more and 15 wt% or less, and R ₂ O ₃ (R = Al) amount is 0 wt%. It is more preferable that the content is from 30% to 30% by weight. Further, other components can be appropriately selected and included in the upper collar layer. By setting it as such a range, an upper collar layer becomes easy to melt | dissolve in a lower collar layer, and a smooth surface can be obtained.

  According to the preferable aspect of this invention, it is preferable that melting | fusing point of an upper collar layer is 500 to 750 degreeC, More preferably, it is 550 to 650 degreeC. By setting the melting point in such a range, the upper eyelid component can enter the lower eyelid layer, and bubbles trapped in the lower eyelid layer can be lifted in the upper eyelid layer. Thereby, the bubble distribution state of the glaze layer can be controlled so that the area of bubbles contained in the upper glaze layer is larger than the area of bubbles contained in the lower glaze layer. Moreover, these contact areas in the interface of the cast iron which is a base material, and a glaze layer become large, and the adhesive force of a base material and a glaze layer can be improved.

  According to the preferable aspect of this invention, it is preferable that the thickness of an upper collar layer is 0.08 mm or more and 0.6 mm or less. By setting it as such thickness, even if it is a sharp shape, a glaze layer can be formed, without producing a crack. The thickness of the upper collar layer is more preferably 0.15 mm or more and 0.5 mm or less.

  Here, the thickness of the upper glaze layer is calculated by subtracting the thickness of the lower glaze layer described above from the thickness of the glaze layer described above.

Use of enamel articles The enamel articles of the present invention are preferably water-related articles such as bathtubs, sinks, wash basins, and hand-washers. More preferably, it is a large water-related article, especially a bathtub.

Method for Manufacturing Enamel Article In a further aspect of the present invention, the present invention provides a method for manufacturing an enamel article according to the present invention described above. That is, the present invention is a method for producing an enamel article in which a glaze layer is formed on a substrate, the step of preparing a substrate, the step of preparing a slurry for forming a glaze layer, and the slurry A method comprising at least a step of applying a slurry to a substrate and a step of firing the substrate to which the slurry is applied at 700 to 900 ° C. is provided.

  The manufacturing method of the enamel article of this invention is demonstrated below for every process. It should be noted that all the matters already described in the present specification for describing the enamel article are also applied as they are in the following description of the manufacturing method.

  In the enamel article manufacturing method of the present invention, first, cast iron as a base material is prepared. In this preparation step, it is preferable to perform shot blasting, sand blasting, and heat treatment as a pretreatment of the substrate in order to remove deposits (sand and graphite) that cause bubbles on the surface of the substrate.

In the enamel article manufacturing method of the present invention, next, a slurry for forming a glaze layer is prepared. As a raw material of the slurry for forming the glaze layer, in addition to glass frit, one or more selected from the group consisting of clay, quartz, boric acid, sodium carbonate, sodium nitrite, sodium aluminate, etc. , Mixed with a solvent such as water can be used. As the glass frit, one or two kinds selected from the group consisting of SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , K ₂ O, CaO, TiO ₂ , Fe ₂ O ₃ , ZnO, P ₂ O _{5 and the} like. The above can be used. The glass frit preferably contains at least 30% by weight of SiO ₂ . The slurry can be prepared by mixing the above-described raw materials and using a known apparatus such as a ball mill. In that case, in order to make it easy to apply to the cast iron which is a base material, it is also preferable to adjust a moisture content.

  In the enamel article manufacturing method of the present invention, next, the slurry prepared in the previous step is applied to the substrate. As the method, a wet method can be preferably used. Thereby, a thin glaze layer with a thickness of 1 mm or less can be applied uniformly. Examples of the application method of the slurry include dipping, pouring (flooring), screen printing and spraying. In addition, it is preferable to degas by previously baking the cast iron.

  In the enamel article manufacturing method of the present invention, the substrate to which the slurry is applied is then fired. As a calcination temperature, 700-900 degreeC is preferable, More preferably, it is 750-850 degreeC. By setting the firing temperature to such a temperature, the rising speed of the bubbles generated in the glaze layer can be reduced, and the bubbles can finally be prevented from reaching the surface of the glaze layer. Thereby, the glaze layer whose ratio of the area of the bubble contained in the field at the substrate side of the glaze layer and the area of the bubble contained in the area on the surface side of the glaze layer is 0: 100 or more and 40:60 or less is included. An enamel article can be obtained. As a result, it is possible to obtain a hollow article that can obtain excellent adhesion through the interface between the base material and the glaze layer.

  In addition, you may provide the drying process for drying the slurry applied to the base material before the said baking process. As the drying method, one or more of heat drying and air drying can be selected.

  Further, in a further aspect of the present invention, in the present invention, the glaze layer includes a lower glaze layer and an upper glaze layer, and a method for producing an enamel article, comprising a step of preparing a base material, A step of preparing a slurry for forming the undercoat layer, a step of applying a slurry for forming the undercoat layer to a substrate, and a substrate to which the slurry for forming the undercoat layer is applied Baked at 700 to 900 ° C., preferably 750 to 850 ° C., a step of preparing a slurry for forming the upper cocoon layer, and a slurry for forming the upper cocoon layer applied to the lower cocoon layer And a step of firing at 760 to 890 ° C., preferably 800 to 850 ° C., a substrate obtained by applying the slurry for forming the upper cocoon layer to the lower cocoon layer is provided. .

  The said manufacturing method of the enamel article in which the said glaze layer contains a lower glaze layer and an upper glaze layer is demonstrated below for every process. It should be noted that all the matters described in the present specification for explaining the enamel article and the enamel layer-containing production method already apply to the following explanation of the production method.

  In the enamel article manufacturing method of the present invention, first, cast iron as a base material is prepared. The base material can be prepared by the same method as the method for manufacturing an enamel article in which the glaze layer is formed on the base material already described.

In the enamel article manufacturing method of the present invention, a slurry for forming a lower cocoon layer (hereinafter also referred to as “slur for the lower cocoon layer”) is prepared. The raw material of the slurry for forming the lower glaze layer can be the same as the raw material of the slurry for forming the glaze layer described above. Preferably, for example, glass frit, clay, quartz, boric acid, A mixture of sodium carbonate, sodium nitrite, sodium aluminate and water can be used. As the glass frit for the lower glazing layer, the same glass frit as described above can be used, but preferably, for example, SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , K ₂ O, CaO, TiO ₂ , Fe _A mixture of ₂ O ₃ and ZnO can be used. It is preferable that the glass frit for the lower glazing layer contains at least 70% by weight or more of SiO ₂ . The slurry can be prepared by mixing the above-described raw materials and using a known apparatus such as a ball mill. In that case, in order to make it easy to apply to the cast iron which is a base material, it is also preferable to adjust a moisture content. The slurry for forming the lower glaze layer is preferably prepared by mixing frit, silica sand, clay, solvent, etc., and wet-grinding with a ball mill.

  In the enamel article manufacturing method of the present invention, next, the slurry for forming the undercoat layer prepared in the previous step is applied to the substrate. As the method, a wet method can be preferably used. Examples of the application method of the slurry include dipping, pouring (flooring), screen printing and spraying.

  In the enamel article manufacturing method of the present invention, next, the base material to which the slurry for forming the undercoat layer is applied is fired. The firing temperature is 700 to 900 ° C, more preferably 750 to 850 ° C. By setting it as such a calcination temperature, it can be made to function as a bubble trap layer, without melt | dissolving a part of an undercoat layer.

  In addition, you may provide the drying process for drying the slurry applied to the base material before the said baking process. As the drying method, one or more of heat drying and air drying can be selected.

In the enamel article manufacturing method of the present invention, a slurry for forming an upper cocoon layer on the lower cocoon layer is prepared. As the raw material of the slurry for forming the upper glaze layer (hereinafter also referred to as “upper glaze layer slurry”), the same raw material as the slurry for forming the glaze layer described above can be used, but preferably For example, a mixture of glass frit, clay, sodium nitrite and water can be used. As the glass frit for the upper glazing layer, the same glass frit as described above can be used, but it is preferably made of, for example, SiO ₂ , Al ₂ O ₃ , K ₂ O, TiO ₂ , ZnO and P ₂ O _5. Mixtures can be used. The upper frit glass frit preferably contains less than 70% by weight of SiO ₂ . The slurry for forming the upper cocoon layer is preferably prepared by putting the frit into a dry ball mill or a vibration mill as it is, or by pulverizing it in the same manner as the lower cocoon layer.

  In the enamel article manufacturing method of the present invention, next, the slurry for forming the upper cocoon layer prepared in the previous step is applied to the lower cocoon layer. As the method, a wet method can be preferably used. Examples of the application method of the slurry include dipping, pouring (flooring), screen printing and spraying.

  In the enamel article manufacturing method of the present invention, next, a base material in which the slurry for forming the upper cocoon layer is applied to the lower cocoon layer is fired. The firing temperature is 760 to 890 ° C, more preferably 800 to 850 ° C. By setting it as such a calcination temperature, an upper glaze layer fuse | melts to a lower glaze layer, and the unevenness | corrugation on the glaze layer surface can be reduced. The difference between the firing temperature of the lower collar layer and the firing temperature of the upper collar layer is preferably less than 100 ° C.

  In addition, you may provide the drying process for drying the slurry applied to the base material before the said baking process. As the drying method, one or more of heat drying and air drying can be selected.

  The present invention will be specifically described based on the following examples, but the present invention is not limited to these examples.

Examples 1-4 and Comparative Examples 1 and 2
(Preparation of base material)
A plate-like test piece made of 100 mm × 100 mm cast iron was prepared. As pretreatment, sandblasting was performed until a metallic luster was produced on the surface.

(Preparation of lower layer slurry)
1000 g of glass frit shown in Table 1, 90 g of clay, 100 g of quartz, 10 g of boric acid, 15 g of sodium carbonate, 3 g of sodium nitrite, 3 g of NaAlO ₂ and 600 g of water were put into a ball mill and pulverized for 3 hours. The obtained slurry was adjusted to have a density of 1.5 to 1.6 g / cm ³ to obtain a lower layer slurry.

(Preparation of upper layer slurry)
1000 g of glass frit shown in Table 2, 60 g of clay, 2 g of sodium nitrite, and 500 g of water were put into a ball mill and pulverized for 4 hours. The obtained slurry was adjusted in moisture so that the density was 1.6 to 1.7 g / cm ^3, and was used as an upper layer slurry.

(Production of enamel specimen)
The slurry for the lower iron layer was wet-glazed with a spray gun on a plate-like test piece made of cast iron of 100 mm × 100 mm and dried for 1 hour. Then, it baked for 90 minutes using the tunnel kiln so that the highest attainment point of the center part of the tunnel kiln becomes the lower iron layer firing temperature described in Table 3, and left to stand after returning to room temperature. Next, the upper bran layer slurry is wet-glazed with a spray gun on the lower braid layer, and the maximum reach point in the center of the tunnel kiln is the upper braid layer firing temperature described in Table 3 for 60 minutes. After firing, the product was allowed to stand until it returned to room temperature to obtain a target enamel specimen.

(Image acquisition by laser microscope)
The obtained enamel specimen was cut, the cross section was mirror-polished, and a test sample was prepared. This test sample was observed using a laser microscope (optical measuring device LEXTOLS4000, manufactured by OLYMPUS). (Objective lens 20 times, laser observation; see FIG. 1). An image of 0.5 mm × 2 mm was acquired so that the base material and the glaze layer were accommodated as an observation region. A reference line that linearly approximated the interface between the glaze layer and the substrate in the acquired image was provided.

(Measurement of the thickness of the glaze layer)
The thickness of the glaze layer in the image obtained with the laser microscope was measured. The thickness of the glaze layer was as shown in Table 4. The thickness of the glaze layer was defined as the minimum value of the vertical distance from the reference line to the surface of the glaze layer.

(Bubble amount measurement 1)
The amount of bubbles contained in the glaze layer was measured using image analysis software (WINROOF ver6.5.1, MITANI CORPORATION). For the measurement, an image obtained with the above laser microscope was used. As compared with the substrate surface, the concave portion was selected as a bubble, selected by binarization processing, and the area was acquired by a shape feature command. The base material of the glaze layer when the glaze layer is divided into an area on the base material side of the glaze layer and an area on the surface side of the glaze layer by an intermediate line located at half the thickness of the glaze layer from the base material surface The ratio of the area of bubbles contained in the region on the side and the area of bubbles contained in the region on the surface side of the glaze layer was determined. Here, the “intermediate line” means a line at a position corresponding to 50 from the reference line, where 100 is the length from the reference line to a line obtained by linear approximation of the surface of the glaze layer. The results were as shown in Table 3.

(Bubble amount measurement 2)
The amount of bubbles contained in the glaze layer was measured using image analysis software (WINROOF ver6.5.1, MITANI CORPORATION). For the measurement, an image obtained with the above laser microscope was used. As compared with the substrate surface, the concave portion was selected as a bubble, selected by binarization processing, and the area was acquired by a shape feature command. With respect to the area of the bubbles contained in the entire glaze layer, the ratio of the area of the bubbles contained in each region from the reference line to 0.05 mm and 0.1 mm in the surface direction of the glaze layer was determined by the following formulas. The results were as shown in Table 4.
-Ratio of bubbles contained in the area from the reference line to 0.05 mm (%) =
(Bubble area contained in the region from the reference line to 0.05 mm) ÷ (Bubble area contained in the entire glaze layer) × 100
-Ratio of bubbles contained in the region from the reference line to 0.1 mm (%) =
(Area of bubbles contained in the region from the reference line to 0.1 mm) ÷ (Area of bubbles contained in the entire glaze layer) × 100

(Adhesion test)
The obtained enamel specimen was cut into 3 cm × 3 cm to prepare a sample. An adhesive (Bond E250, manufactured by Konishi Co., Ltd.) was applied to the entire surface of the glaze layer of this sample and the entire surface of the base material opposite to the surface. A jig with a hook of 3 cm x 3 cm is attached to each adhesive application surface, and after leaving it to stand overnight, it is fully bonded, and then a pull test is performed with an autograph (AG-5000B, manufactured by Shimadzu Corporation). It was. The pulling speed was 1 mm per minute, and the force when the glaze layer and the substrate were peeled was evaluated as the adhesion (g / cm ² ) of the enamel specimen. In addition, about what peeled except the interface of a glaze layer and a base material, since it was different from the objective of this test, it excluded from data. For example, when cracks in the glaze layer occurred due to cracks that occurred when the enamel specimen was cut for sample preparation, or when the adhesive part that bonded the jig and enamel specimen was peeled off Excluded from. The results were as shown in Table 4.

(Appearance evaluation 1)
Appearance evaluation was performed on the samples of Example 3 and Comparative Example 2. That is, the surface of the sample was visually evaluated. A photograph of the surface is shown in FIG. As a result, the sample of Example 3 showed no black defects, whereas the sample of Comparative Example 2 showed many black defects. The “black defect” is a hole formed on the surface of the glaze layer when bubbles generated during firing bounce on the surface of the glaze layer, and those that have cooled and solidified before the glaze flows into this hole. means.

(Appearance evaluation 2)
As an index indicating the appearance of the glaze layer surface, the number of black defects in an arbitrary area of 2 cm × 2 cm was measured on the glaze layer surface of the obtained enamel specimen. The results were as shown in Table 4.

Example 5 and Comparative Example 3
An enamel specimen was prepared in the same manner as in Example 3, except that the glass frit for the lower glaze layer had the composition shown in Table 5 and the firing time for the lower glaze layer was 60 minutes. Table 5 also shows the composition of the glass frit for the undercoat layer of Example 3 as a reference.

(Measurement of the thickness of the glaze layer)
The obtained enamel specimen was cut, the cross section was mirror-polished, and a test sample was prepared. About this test sample, the image was acquired using the laser microscope and the thickness of the glaze layer in this image was measured by the method similar to the above-mentioned. The film thickness was as shown in Table 8.

(Measurement of the composition of the lower layer after firing)
For the samples of Examples 3 and 5 and Comparative Example 3, the composition of the lower heel layer was calculated by the following method. That is, the composition of the lower eyelid layer (see FIG. 3) in the image obtained using the laser microscope was obtained by obtaining a backscattered electron image with an environmental control scanning electron microscope (SEM-Quanta, manufactured by Shimadzu Corporation) (conditions) Is an acceleration voltage of 10 kV and a magnification of 1000 times; see FIG. 4), and the obtained backscattered electron image is taken into an EDS (energy dispersive X-ray analyzer) (Noran System7, manufactured by Shimadzu Corporation), using Point & shot mode. Calculated.

(Calculation method of the composition of the lower bran layer by EDS)
Element setting: A qualitative analysis was performed in advance, all elements considered to be contained were set to “always identified”, and other elements were set to “non-selected” to obtain element mapping images (FIG. 4).
Analysis settings: Analysis was performed in the order of spectrum collection → sum peak removal, escape peak removal → automatic quantification.
From the obtained atomic weight (% by weight), oxygen and Fe and C, which are the main components of cast iron, were removed, and the remaining components were converted to the weight of the oxide. The mass (% by weight) of the obtained oxide was calculated so as to be a total of 100% by weight, and the area from the substrate surface to the surface of the glaze layer was 0.05 mm (within the range of the lower glaze layer). Ingredients were calculated. Here, the “region from the substrate surface to 0.05 mm in the surface direction of the glaze layer” is a region from the reference line to 0.05 mm in the surface direction of the glaze layer. The results were as shown in Table 6.

(Unevenness evaluation)
About the samples of Examples 3 and 5 and Comparative Example 3 having different compositions of the lower glaze layer after firing, the unevenness state of the glaze layer surface of each sample due to the difference in composition was visually evaluated as follows. That is, the number of black defects in an arbitrary area of 1 cm × 1 cm on the surface of the glaze layer of each sample was measured. The results were as shown in Table 6.

(Calculation of undissolved SiO ₂ content)
For the samples of Examples 3 and 5 and Comparative Example 3, the amount of undissolved SiO ₂ contained in the region from the substrate surface to 0.05 mm (within the region of the lower glaze layer) was calculated. Analyze the element mapping image obtained by the EDS method for calculating the composition of the lower bran layer, and undissolve the part where the total of the element amount of Si (wt%) and the element amount of O (wt%) is 90 wt% or more The state was SiO ₂ . The undissolved SiO ₂ part was selected by the binarization processing of image analysis software (WINROOF ver6.5.1, MITANI CORPORATION), and the area ratio was obtained by the shape feature command. The amount of SiO _{2 in} an undissolved state was calculated from the following formula. The results were as shown in Table 6.
・ Undissolved SiO ₂ amount (%) = (area of undissolved SiO ₂ contained in a region from the reference line to the surface of the glaze layer up to 0.05 mm) ÷ (surface direction of the glaze layer from the reference line) Total area of the area up to 0.05 mm) × 100.

(Bubble amount measurement 1)
With respect to the samples of Example 5 and Comparative Example 3, the area ratio of the bubbles was evaluated by the same method as in the bubble amount measurement 1 described above. The results were as shown in Table 7. Table 7 also shows the bubble area ratio of Example 3 as a reference.

(Bubble amount measurement 2)
With respect to the samples of Example 5 and Comparative Example 3, 0.05 mm in the surface direction of the glaze layer from the reference line with respect to the area of the bubbles contained in the entire glaze layer and 0. The ratio of the area of the bubbles contained in each region up to 1 mm was determined. The results were as shown in Table 8. In Table 8, the ratio of the area of bubbles in Example 3 is also shown as a reference.

(Adhesion test)
The samples of Example 5 and Comparative Example 3 were subjected to an adhesion test in the same manner as the adhesion test described above. The results were as shown in Table 8. In Table 9, the adhesion force of Example 3 is also shown as a reference.

Claims (9)

A hollow article in which a glaze layer is formed on a substrate,
The base material is cast iron;
Included in the former when the glaze layer is divided into an area on the base material side of the glaze layer and an area on the surface side of the glaze layer by an intermediate line located at half the thickness of the glaze layer from the base material surface the area of bubbles, the ratio of the area of the air bubbles contained in the latter is 0: Ri der 100 or 40:60 or less,
The thickness of the glaze layer is 0.1 mm or more and 1.0 mm or less,
Composition after firing in the region of from the substrate surface to 0.05mm toward the surface of the glaze layer, _SiO 2> Ru 60 weight% der, enamel article. A ratio of the area of bubbles included in the region from the surface of the base material to 0.1 mm in the surface direction of the glaze layer is included in the entire glaze layer, and the thickness of the glaze layer is 0.2 mm or more. The enamel article according to claim 1 , which is 35% or less with respect to the area of the bubbles. The ratio of the area of undissolved SiO ₂ contained in a region from the substrate surface to 0.05 mm in the surface direction of the glaze layer is 15% to 70% with respect to the total area of the region. Item 5. The enamel article according to item 1 or 2 . The glaze layer includes a lower glaze layer and an upper glaze layer formed on the substrate, and the composition of the lower glaze layer after firing has the following relationship:
55 wt% ≦ RO ₂ ≦ 80 wt% (R = Si),
0 wt% ≦ R ₂ O ≦ 20 wt% (R = Na, K),
0 wt% ≦ RO ≦ 15 wt% (R = Ca, Zn, Mg, Ba) and 0 wt% ≦ R ₂ O ₃ ≦ 30 wt% (R = Al)
The enamel article as described in any one of Claims 1-3 which satisfy | fills. The enamel article according to any one of claims 1 to 4 , wherein the enamel article is a water-based article. The enamel article according to claim 5 , wherein the water-related article is a bathtub. It is a manufacturing method of the enamel article according to any one of claims 1 to 6,
Preparing the substrate;
Preparing a slurry for forming the glaze layer;
Applying the slurry to the substrate;
And firing at 750 to 850 ° C. the base material to which the slurry is applied,
A method wherein the method of applying the slurry to the substrate is a wet method. It is a manufacturing method of the enamel article according to any one of claims 1 to 6 , wherein the glaze layer includes a lower glaze layer and an upper glaze layer,
Preparing the substrate;
Preparing a slurry for forming an undercoat layer on the substrate;
Applying a slurry for forming the undercoat layer to the substrate;
Firing the substrate to which the slurry for forming the lower glazing layer is applied at 750 to 850 ° C .;
Preparing a slurry for forming an upper cocoon layer on the lower cocoon layer;
Applying a slurry for forming the upper cocoon layer to the lower cocoon layer;
And firing at 800 to 850 ° C. a substrate in which the slurry for forming the upper cocoon layer is applied to the lower cocoon layer,
The difference between the temperature at which the substrate to which the slurry for forming the lower glazing layer is applied is baked and the temperature at which the substrate to which the slurry for forming the upper cocoon layer is applied is baked is 100. A method that is less than ° C. The method for applying the slurry for forming the lower cocoon layer to the substrate and the method for applying the slurry for forming the upper cocoon layer to the lower cocoon layer are wet methods. the method of.