KR20240041163A - Hydrophilic enamel for cooking equipment and manufacturing method therefor - Google Patents

Abstract

The disclosed invention relates to hydrophilic enamel for cooking appliances and a method of manufacturing the same.
Hydrophilic enamel for cooking appliances according to one embodiment may include, in weight percent, 0.05 to 20% of hydrophilic crystal mineral and the remainder enamel frit. The hydrophilic crystal mineral may include SiO ₂ , Al ₂ O ₃ , K ₂ O, Li ₂ O, NaF, and MgO.

Description

Hydrophilic enamel for cooking equipment and manufacturing method therefor {Hydrophilic enamel for cooking equipment and manufacturing method therefor}

The disclosed invention relates to hydrophilic enamel for cooking appliances and a method of manufacturing the same.

Enamel can be used as an interior coating material for cooking appliances such as ovens and microwave ovens. Therefore, enamel is easily contaminated by contaminants derived from food during cooking, and contaminants can be solidified by high temperatures.

Methods for cleaning contaminants inside cooking appliances include self-cleaning and steam cleaning.

However, the self-cleaning method has the problem of requiring a lot of energy and time because it is performed for more than 5 hours at a high temperature of 500°C or higher. Additionally, the steam cleaning method has the problem of making it difficult to clean stuck contaminants.

Therefore, there is a demand for enamel for cooking appliances that can easily remove contaminants using only moisture at room temperature.

The purpose of the present invention to solve the above problems is to provide a hydrophilic enamel for cooking appliances and a method of manufacturing the same, which improves cleaning properties by strengthening surface hydrophilicity.

Hydrophilic enamel for cooking appliances according to one embodiment may include, in weight percent, 0.05 to 20% of hydrophilic crystal mineral and the remainder enamel frit. The hydrophilic crystal mineral may include SiO ₂ , Al ₂ O ₃ , K ₂ O, Li ₂ O, NaF, and MgO.

A method of manufacturing hydrophilic enamel for cooking appliances according to an embodiment includes, in weight percent, SiO ₂ : 40 to 55%, Al ₂ O ₃ : 7 to 25%, K ₂ O: 6 to 13%, MgO: 2 to 20. %, Li ₂ O: 1 to 7%, NaF: 3 to 15%, Fe ₂ O ₃ : 1 to 10%, B ₂ O ₃ : 5 to 10%, and the remaining metal oxides; manufacturing a frit by dissolving the raw materials and then cooling them; Grinding the frit to produce liquid and powder coating materials; Coating the liquid and powder paint on the metal surface of enamel for cooking appliances; And it may include the step of firing the coated enamel for cooking appliances.

A method of manufacturing hydrophilic enamel for cooking appliances according to an embodiment includes at least one of SiO ₂ , B ₂ O ₃ and Al ₂ O ₃ as a first constituent element, and K ₂ O and Na ₂ O as a second constituent element. and Li ₂ O, and as a third constituent element, at least one of CoO, CuO, NiO and NaF, and as a fourth constituent element MgO, CeO, ZrO ₂ , CaO, TiO ₂ and Fe ₂ O. Preparing raw materials containing at least one of ₃ ; manufacturing a frit by dissolving the raw materials and then cooling them; Grinding the frit and the hydrophilic crystal mineral and then mixing them to produce liquid and powder paint; Coating the liquid and powder paint on the metal surface of enamel for cooking appliances; And it may include the step of firing the coated enamel for cooking appliances.

According to an example of the present invention, it is possible to provide a hydrophilic enamel for cooking appliances that improves cleaning properties and facilitates the removal of contaminants with just moisture at room temperature, and a method for manufacturing the same.

However, the effects that can be achieved by the hydrophilic enamel for cooking appliances and the method of manufacturing the same according to the embodiments of the present invention are not limited to those mentioned above, and other effects not mentioned can be found from the description below to which the present invention belongs. It will be clearly understandable to those with ordinary knowledge in the technical field.

Figure 1 is a flow chart showing a method of manufacturing hydrophilic enamel for cooking appliances according to an embodiment.
Figure 2 is an image taken using a SEM (scanning electron microscope) of the surface of hydrophilic enamel for a cooking appliance according to an embodiment.
Figure 3 is a graph showing PXRD (powder X-ray diffraction) analysis of the surface of hydrophilic enamel for cooking appliances according to one embodiment.
Figure 4 is an image showing the results of a cleaning test on enamel for cooking appliances without introducing hydrophilic minerals.
Figure 5 is an image showing the results of a cleaning test on hydrophilic enamel for cooking appliances according to an embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following examples are presented to sufficiently convey the idea of the present invention to those skilled in the art. The present invention is not limited to the embodiments presented herein and may be embodied in other forms. In order to clarify the present invention, the drawings may omit illustrations of parts unrelated to the description and may slightly exaggerate the sizes of components to aid understanding.

Throughout the specification, when a part is said to “include” a certain element, this means that it may further include other elements rather than excluding other elements, unless specifically stated to the contrary.

Singular expressions include plural expressions unless the context clearly makes an exception.

Hydrophilic enamel for cooking appliances according to one embodiment may include, in weight percent, 0.05 to 20% of hydrophilic crystal mineral and the remainder enamel frit.

The disclosed invention relates to enamel for painting the interior of cooking appliances, and unlike existing vitreous enamel, it may contain a crystalline mineral with high hydrophilicity. Through this, it is possible to remove fixed contaminants with just moisture at room temperature, thereby creating enamel with excellent cleaning properties.

If the hydrophilic crystal mineral is less than 0.05%, sufficient hydrophilicity may not be secured and it may be difficult to achieve the desired cleaning property. However, if the hydrophilic crystal mineral exceeds 20%, the adhesion and strength of the enamel may decrease and surface defects may occur.

Meanwhile, among the methods of manufacturing hydrophilic enamel for cooking appliances described later, the enamel manufactured by the first manufacturing method may include 10 to 20% of hydrophilic crystal mineral and the remaining enamel frit.

The hydrophilic crystal mineral may include SiO ₂ , Al ₂ O ₃ , K ₂ O, Li ₂ O, NaF, and MgO.

Conventional hydrophilic enamel was manufactured using P ₂ O ₅ , TiO ₂ , etc. However, conventional hydrophilic enamel had a contact angle with water of 50 to 60 degrees, which was insufficient to remove contaminants. In addition, when adding a large amount of additives to improve hydrophilicity, there was a problem that essential properties such as adhesion to metal and chemical resistance were deteriorated.

Meanwhile, hydrophilic crystal minerals include hydrophilic elements or functional groups such as alkali metal ions (Li ⁺ , K ⁺ , Mg ²⁺ , etc.), fluorine groups (-F), and hydroxy groups (-OH). In addition, hydrophilic crystal minerals have a layered structure and can contain moisture between layers, thereby realizing high hydrophilicity.

The hydrophilic crystal mineral may include at least one of phlogopite, muscovite, vermiculite, biotite, and polylithionite.

The phlogopite can be formed by controlling Al ₂ O ₃ , K ₂ O, MgO, NaF, and SiO ₂ to an optimal ratio. Specifically, the phlogopite contains, in weight percent, Al ₂ O ₃ : 12 to 16%, K ₂ O: 6 to 12%, MgO: 22 to 30%, NaF: 7 to 10%, and the remainder SiO ₂ It can be included.

The muscovite can be formed by controlling Al ₂ O ₃ , K ₂ O, NaF, and SiO ₂ to an optimal ratio. Specifically, the muscovite may include, in weight percent, Al ₂ O ₃ : 28 to 35%, K ₂ O : 9 to 13%, NaF : 6 to 9%, and the remainder SiO ₂ .

The vermiculite and biotite can be formed by controlling Al ₂ O ₃ , MgO, Fe ₂ O ₃ , NaOH, and SiO ₂ to an optimal ratio. Specifically, the vermiculite and biotite may include, in weight percent, Al ₂ O ₃ : 8 to 13%, MgO or Fe ₂ O ₃ : 7 to 25%, NaOH: 25 to 50%, and the remainder SiO ₂ there is.

The polyrichionite can be formed by controlling Al ₂ O ₃ , Li ₂ O, K ₂ O, NaF, and SiO ₂ to an optimal ratio. Specifically, the polyrichionite is, in weight percent, Al ₂ O ₃ : 20 to 23%, Li ₂ O: 4 to 6%, K ₂ O: 8 to 13%, NaF: 6 to 10%, and the remainder. It may include SiO ₂ .

The hydrophilic enamel for cooking appliances containing the hydrophilic crystalline mineral may have a contact angle with water of 30 degrees or less. That is, the hydrophilic enamel for cooking appliances according to one embodiment can implement high hydrophilicity.

In this way, enamel with improved hydrophilicity can improve cleaning properties because moisture can penetrate the interface between the enamel surface and contaminants and contaminants can easily separate and float.

Next, a method for manufacturing hydrophilic enamel for cooking appliances according to another aspect of the disclosed invention will be described.

Figure 1 is a flowchart showing a method of manufacturing hydrophilic enamel for cooking appliances according to an embodiment.

Referring to FIG. 1, a method of manufacturing hydrophilic enamel for cooking appliances according to an embodiment may include a series of raw material preparation, frit manufacturing, paint manufacturing, coating, and firing steps.

The method for manufacturing hydrophilic enamel for cooking appliances according to an example of the disclosed invention includes a first manufacturing method of producing enamel by generating hydrophilic crystalline minerals from raw materials, and a second manufacturing method of manufacturing enamel by mixing the hydrophilic crystalline minerals themselves. may include.

First, the first manufacturing method will be described in detail.

A method of manufacturing hydrophilic enamel for cooking appliances according to an embodiment includes, in weight percent, SiO ₂ : 40 to 55%, Al ₂ O ₃ : 7 to 25%, K ₂ O: 6 to 13%, MgO: 2 to 20. %, Li ₂ O: 1 to 7%, NaF: 3 to 15%, Fe ₂ O ₃ : 1 to 10%, B ₂ O ₃ : 5 to 10%, and the remaining metal oxides; manufacturing a frit by dissolving the raw materials and then cooling them; Grinding the frit to produce liquid and powder coating materials; Coating the liquid and powder paint on the metal surface of enamel for cooking appliances; And it may include the step of firing the coated enamel for cooking appliances.

First, in weight percent, SiO ₂ : 40 to 55%, Al ₂ O ₃ : 7 to 25%, K ₂ O: 6 to 13%, MgO: 2 to 20%, Li ₂ O: 1 to 7%, NaF : 3 to 15%, Fe ₂ O ₃ : 1 to 10%, B ₂ O ₃ : 5 to 10%, and the remaining metal oxides can be prepared.

If the SiO ₂ content is less than 40%, the strength of the enamel may decrease. However, if the SiO ₂ content exceeds 55%, chemical resistance may become inferior.

Contrary to SiO ₂ , if the Al ₂ O ₃ content is less than 7%, chemical resistance may be reduced. However, if the Al ₂ O ₃ content exceeds 25%, the strength of the enamel may decrease.

If the content of K ₂ O, MgO, Li ₂ O, NaF, and Fe ₂ O ₃ is low, the uniformity of the paint may be poor or it may be difficult for hydrophilic crystalline minerals to form. However, if the contents of K ₂ O, MgO, Li ₂ O, NaF and Fe ₂ O ₃ are too high, chemical resistance, strength and surface adhesion may be reduced.

If the B ₂ O ₃ content is less than 5%, adhesion to the metal may decrease. However, if the B ₂ O ₃ content exceeds 10%, the strength of the enamel may become poor.

The remaining ingredients may include metal oxides to improve adhesion to metal, chemical resistance, and mechanical strength. The metal oxide may include CeO, ZrO ₂ , CaO, TiO ₂ and MnO.

A frit can be manufactured by dissolving the raw materials and then cooling them.

In the step of manufacturing the frit, the raw materials may be dissolved at 1000 to 1400°C.

If the dissolution temperature is low, it may be difficult for each raw material to completely dissolve. However, if the dissolution temperature is too high, components with low boiling points may vaporize and change the composition of the melt.

Next, the frit can be pulverized to produce liquid and powder paints.

In the step of manufacturing the liquid and powder paints, the frit may be mechanically pulverized into fine particles of 0.1 to 30 ㎛. Afterwards, liquid and powder paints can be prepared by mixing the fine particles with water and a thickener. If the viscosity of liquid or powder paint is too low or high, coating may not be done uniformly. Therefore, there is a need to achieve a viscosity similar to that of conventional liquid and powder paints.

The liquid and powder paints can be uniformly sprayed and coated on the metal surface of the enamel for cooking appliances.

Meanwhile, if necessary, a base paint may be coated on the metal surface of the enamel for a cooking appliance before coating the liquid or powder coating on the metal surface of the enamel for a cooking appliance.

If the base paint is not coated, a thick coating layer of 100㎛ or more may be formed. However, when the base paint is first coated to improve surface adhesion and then the liquid and powder paints are coated, a relatively thin coating layer can be formed. Therefore, by coating the base paint first, raw materials can be saved.

The coated enamel for cooking appliances can be fired. The firing step may be performed at 800 to 900°C.

If the firing temperature is low, the adhesion and strength of the enamel may decrease. However, if the firing temperature is too high, surface defects may occur on the surface of the product after firing.

The first manufacturing method seeks to produce hydrophilic crystalline minerals by controlling the components and range of raw materials. The enamel manufactured by the first manufacturing method may contain 10 to 20% of hydrophilic crystal mineral and the remaining enamel frit.

Meanwhile, the hydrophilic crystal mineral produced by the first manufacturing method may include SiO ₂ , Al ₂ O ₃ , K ₂ O, Li ₂ O, NaF, and MgO. In addition, the hydrophilic crystal mineral produced by the first manufacturing method is at least one of phlogopite, muscovite, vermiculite, biotite, and polylithionite. It can contain one.

Next, the second manufacturing method will be described in detail.

A method of manufacturing hydrophilic enamel for cooking appliances according to an embodiment includes at least one of SiO ₂ , B ₂ O ₃ and Al ₂ O ₃ as a first constituent element, and K ₂ O and Na ₂ O as a second constituent element. and Li ₂ O, and as a third constituent element, at least one of CoO, CuO, NiO and NaF, and as a fourth constituent element MgO, CeO, ZrO ₂ , CaO, TiO ₂ and Fe ₂ O. Preparing raw materials containing at least one of ₃ ; manufacturing a frit by dissolving the raw materials and then cooling them; Grinding the frit and the hydrophilic crystal mineral and then mixing them to produce liquid and powder paint; Coating the liquid and powder paint on the metal surface of enamel for cooking appliances; And it may include the step of firing the coated enamel for cooking appliances.

First, it contains at least one of SiO ₂ , B ₂ O ₃ and Al ₂ O ₃ as a first constituent element, and contains at least one of K ₂ O, Na ₂ O and Li ₂ O as a second constituent element, and It is possible to prepare a raw material containing at least one of CoO, CuO, NiO and NaF as the third constituent element, and at least one of MgO, CeO, ZrO ₂ , CaO, TiO ₂ and Fe ₂ O ₃ as the fourth constituent element. there is.

The first constituent element, second constituent element, third constituent element, and fourth constituent element are divided into components that perform the same function. Therefore, within each group, they can be used interchangeably. For example, among the fourth constituent elements, CaO can be substituted for MgO and used.

The raw materials may include, in weight percent, a first constituent element: 67 to 79%, a second constituent element: 10 to 20%, a third constituent element: 1 to 7%, and the remaining fourth constituent element.

The first component may be added to form a network as the main framework of the enamel.

If the content of the first constituent element is less than 67%, the strength of the enamel may decrease and surface defects may occur. However, if the content of the first constituent element exceeds 79%, the adhesion and chemical resistance of the enamel may be poor.

The second component can be used as a flux. The melting point of the first component is around 2000°C, but by adding the second component, the melting point can be lowered to below 1400°C.

If the content of the second component is less than 10%, the chemical resistance of the enamel and the uniformity of the paint may decrease. However, if the content of the second component exceeds 20%, the strength of the enamel may decrease.

The third component may be added to improve adhesion through a redox reaction with the metal surface.

More specifically, adhesion can be improved through oxide generation, stabilization, and redox reaction.

In the oxide generation step, the metal may be oxidized to form an oxide layer on the metal surface. Next, the ionization of the metal may be accelerated and stabilized as it is absorbed into the enamel. Lastly, as metal surface corrosion and dendrites are formed through redox reactions, the adhesion between the enamel and the metal surface can be improved.

If the third component content is less than 1%, the adhesion of the enamel may be poor. However, if the third component content exceeds 7%, the strength and chemical resistance of the enamel may decrease.

The fourth component may be added to strengthen the physical properties of enamel.

If the content of the fourth component is low, the adhesion of the enamel and the uniformity of the paint may decrease. However, if the content of the fourth component is excessive, the strength of the enamel may become inferior.

A frit can be manufactured by dissolving the raw materials and then cooling them.

In the step of manufacturing the frit, the raw materials may be dissolved at 1000 to 1400°C.

If the dissolution temperature is low, it may be difficult for each raw material to completely dissolve. However, if the dissolution temperature is too high, components with low boiling points may vaporize and change the composition of the melt.

Next, the frit and the hydrophilic crystalline mineral can be pulverized and then mixed to produce liquid and powder paints.

The hydrophilic crystal mineral may include SiO ₂ , Al ₂ O ₃ , K ₂ O, Li ₂ O, NaF, and MgO. Additionally, the hydrophilic crystal mineral may include at least one of phlogopite, muscovite, vermiculite, biotite, and polylithionite.

In this way, the second manufacturing method can be distinguished from the first manufacturing method in that the paint is manufactured by mixing the hydrophilic crystalline mineral itself with the frit.

In the step of manufacturing the liquid and powder paints, the frit and the hydrophilic crystalline mineral may be mechanically ground into fine particles of 0.1 to 30 ㎛ and uniformly mixed through a mixer.

Afterwards, liquid and powder paints can be prepared by mixing the fine particles with water and a thickener. If the viscosity of liquid or powder paint is too low or high, coating may not be done uniformly. Therefore, there is a need to achieve a viscosity similar to that of conventional liquid and powder paints.

The liquid and powder paints can be uniformly sprayed and coated on the metal surface of the enamel for cooking appliances.

Meanwhile, as in the first manufacturing method, if necessary, a base paint may be coated on the metal surface of the enamel for a cooking appliance before coating the liquid or powder coating on the metal surface of the enamel for a cooking appliance.

If the base paint is not coated, a thick coating layer of 100㎛ or more may be formed. However, when the base paint is first coated to improve surface adhesion and then the liquid and powder paints are coated, a relatively thin coating layer can be formed. Therefore, by coating the base paint first, raw materials can be saved.

The coated enamel for cooking appliances can be fired. The firing step may be performed at 800 to 900°C.

If the firing temperature is low, the adhesion and strength of the enamel may decrease. However, if the firing temperature is too high, surface defects may occur on the surface of the product after firing.

The second manufacturing method manufactures enamel by mixing the hydrophilic crystal minerals themselves, so it is relatively easy to control the content of the hydrophilic crystal minerals. Therefore, the content of the hydrophilic crystalline mineral can be further reduced to minimize raw material costs while realizing the hydrophilic effect. Through this, the enamel manufactured by the second manufacturing method may include 0.05 to 20% of the hydrophilic crystal mineral and the remaining enamel frit.

Meanwhile, in order to facilitate surface expression of the hydrophilic crystalline mineral, enamel may be manufactured after preparing a separate additive.

Specifically, the additive can be prepared by mixing pulverized hydrophilic crystalline minerals with SiO ₂ , Al ₂ O ₃ and NaF and separately dissolving them at a temperature of 1200°C or higher. Next, the paint can be manufactured by uniformly mixing it with the pulverized frit. At this time, the additive may be added in an amount of 0.01 to 10% by weight.

Hydrophilic crystals have a tendency to stick together well. Therefore, it may be difficult to distribute it uniformly. Therefore, by mixing the hydrophilic crystal mineral with SiO ₂ , Al ₂ O ₃ and NaF, particle dispersibility can be increased so that the hydrophilic crystals are uniformly distributed on the enamel surface.

Below, examples and comparative examples are described to aid understanding of the present invention. However, the following description only corresponds to an example of the content and effects of the present invention, and the scope and effects of the present invention are not necessarily limited thereto.

{Example}

As a first manufacturing method, in weight%, SiO ₂ : 45%, Al ₂ O ₃ : 10%, K ₂ O: 8%, MgO: 9%, Li ₂ O: 5%, NaF: 10%, Fe ₂ Raw materials containing O ₃ : 5%, B ₂ O ₃ : 7%, and the remaining metal oxide (CeO) were prepared, dissolved at 1400°C, and then cooled to prepare a frit. Afterwards, the frit was pulverized to a size of 10 ㎛, a paint was prepared, coated on a metal surface, and then fired at 850°C to produce hydrophilic enamel for cooking appliances.

As a second manufacturing method, raw materials containing SiO ₂ and Al ₂ O ₃ : 73%, K ₂ O: 15%, NaF: 5%, and the remaining MgO were prepared in weight percent, dissolved at 1400°C, and then cooled. Frit was manufactured. Afterwards, the frit and phlogopite were pulverized and mixed to a size of 10 ㎛, then a paint was prepared, coated on the metal surface, and then fired at 850°C to produce hydrophilic enamel for cooking appliances.

<Hydrophilic crystalline mineral analysis>

Figure 2 is an image taken using a SEM (scanning electron microscope) of the surface of hydrophilic enamel for a cooking appliance according to an embodiment.

Referring to Figure 2, hydrophilic crystalline minerals formed as plate-shaped particles can be seen on the surface of hydrophilic enamel for cooking appliances.

Figure 3 is a graph showing PCRD (powder X-ray diffraction) analysis of the surface of hydrophilic enamel for cooking appliances according to an embodiment.

Referring to Figure 3, the X-ray diffraction pattern of the hydrophilic crystal phase was analyzed through PCRD (powder X-ray diffraction) analysis, and it can be confirmed that the hydrophilic crystal phase was formed in the enamel.

<Contact angle measurement>

The contact angle measurement test was measured by dropping 4.0 μl of water on the specimen at room temperature (25°C) using contact angle measuring equipment from KRUSS.

As a result of the contact angle measurement test, the contact angle of the hydrophilic enamel for cooking appliances according to one embodiment was measured to be 30 degrees. That is, the hydrophilic enamel for cooking appliances according to one embodiment had very high hydrophilicity.

<Cleanability test>

The cleanability test was performed by contaminating the specimen with monster mash contaminants and gravy sauce/shortening contaminants at room temperature, and then cleaning it with moisture at room temperature.

The monster mash contaminant was manufactured according to the American cleaning evaluation standards, and the gravy sauce/shortening contaminant was manufactured according to the European cleaning evaluation standards.

FIG. 4 is an image showing the results of a cleaning test on enamel for cooking appliances without introducing hydrophilic minerals, and FIG. 5 is an image showing the results of a cleaning testing test on hydrophilic enamel for cooking appliances according to an embodiment.

4 and 5, the upper contaminant is the monster mash contaminant, and the lower contaminant is the gravy sauce/shortening contaminant.

Referring to Figures 4 and 5, it was confirmed that the hydrophilic enamel for cooking appliances according to one embodiment had improved hydrophilicity and that most of the contaminants were removed with just moisture at room temperature.

As such, according to an example of the disclosed invention, it is possible to provide a hydrophilic enamel for cooking appliances and a method for manufacturing the same, which improves cleaning properties by strengthening the surface hydrophilicity and facilitates the removal of contaminants with only moisture at room temperature.

Claims (20)

By weight, it contains 0.05 to 20% hydrophilic crystalline minerals and the remainder enamel frit;
The hydrophilic crystalline mineral is,
Hydrophilic enamel for cooking appliances, comprising SiO ₂ , Al ₂ O ₃ , K ₂ O, Li ₂ O, NaF and MgO. According to paragraph 1,
The hydrophilic crystal mineral is,
A hydrophilic enamel for cooking appliances, comprising at least one of phlogopite, muscovite, vermiculite, biotite, and polylithionite. According to paragraph 2,
The phlogopite is,
A hydrophilic enamel for cookware comprising, in weight percent: Al ₂ O ₃ : 12 to 16%, K ₂ O: 6 to 12%, MgO: 22 to 30%, NaF: 7 to 10% and the balance SiO ₂ . According to paragraph 2,
The muscovite is,
A hydrophilic enamel for cookware comprising, in weight percent, Al ₂ O ₃ : 28 to 35%, K ₂ O : 9 to 13%, NaF : 6 to 9% and the balance SiO ₂ . According to clause 2,
The vermiculite and biotite are,
Hydrophilic enamel for cookware comprising, in weight percent, Al ₂ O ₃ : 8 to 13%, MgO or Fe ₂ O ₃ : 7 to 25%, NaOH: 25 to 50% and the balance SiO ₂ . According to paragraph 2,
The polyrichionite is,
Hydrophilic enamel for cookware comprising, in weight percent: Al ₂ O ₃ : 20 to 23%, Li ₂ O: 4 to 6%, K ₂ O: 8 to 13%, NaF: 6 to 10% and the balance SiO ₂ . According to paragraph 1,
Hydrophilic enamel for cooking appliances with a contact angle with water of 30 degrees or less. In weight percent, SiO ₂ : 40 to 55%, Al ₂ O ₃ : 7 to 25%, K ₂ O: 6 to 13%, MgO: 2 to 20%, Li ₂ O: 1 to 7%, NaF: 3 to 15%, Fe ₂ O ₃ : 1 to 10%, B ₂ O ₃ : 5 to 10%, and the remaining metal oxides;
manufacturing a frit by dissolving the raw materials and then cooling them;
Grinding the frit to produce liquid and powder coating materials;
Coating the liquid and powder paint on the metal surface of enamel for cooking appliances; and
A method of manufacturing hydrophilic enamel for cooking appliances, comprising the step of baking the coated enamel for cooking appliances. According to clause 8,
Before coating the liquid and powder paint on the metal surface of the enamel for cooking appliances,
A method of manufacturing hydrophilic enamel for cooking appliances, further comprising coating the metal surface of the enamel for cooking appliances with a base paint. According to clause 8,
The metal oxide is,
Method for producing hydrophilic enamel for cooking appliances, comprising at least one of CeO, ZrO ₂ , CaO, TiO ₂ and MnO. According to clause 8,
In the step of manufacturing the frit,
A method for producing hydrophilic enamel for cooking appliances, wherein the raw materials are dissolved at 1000 to 1400°C. According to clause 8,
In the step of manufacturing the liquid and powder paint,
A method of producing hydrophilic enamel for cooking appliances, wherein the frit is pulverized to 0.1 to 30 ㎛. According to clause 8,
The firing step is,
A method for producing hydrophilic enamel for cooking appliances, carried out at 800 to 900°C. Contains at least one of SiO ₂ , B ₂ O ₃ and Al ₂ O ₃ as the first constituent element,
Contains at least one of K ₂ O, Na ₂ O and Li ₂ O as a second constituent element,
Contains at least one of CoO, CuO, NiO and NaF as a third constituent element,
Preparing a raw material containing at least one of MgO, CeO, ZrO ₂ , CaO, TiO ₂ and Fe ₂ O ₃ as a fourth constituent element;
manufacturing a frit by dissolving the raw materials and then cooling them;
Grinding the frit and the hydrophilic crystal mineral and then mixing them to produce liquid and powder paint;
Coating the liquid and powder paint on the metal surface of enamel for cooking appliances; and
A method of manufacturing hydrophilic enamel for cooking appliances, comprising the step of baking the coated enamel for cooking appliances. According to clause 14,
Before coating the liquid and powder paint on the metal surface of the enamel for cooking appliances,
A method of manufacturing hydrophilic enamel for cooking appliances, further comprising coating the metal surface of the enamel for cooking appliances with a base paint. According to clause 14,
The raw materials are,
Method for producing hydrophilic enamel for cooking appliances, comprising, in weight percent, a first constituent element: 67 to 79%, a second constituent element: 10 to 20%, a third constituent element: 1 to 7%, and the remaining fourth constituent element. . According to clause 14,
The hydrophilic crystalline mineral is,
A method of producing hydrophilic enamel for cooking appliances, comprising at least one of phlogopite, muscovite, vermiculite, biotite, and polylithionite. According to clause 14,
In the step of manufacturing the frit,
A method for producing hydrophilic enamel for cooking appliances, wherein the raw materials are dissolved at 1000 to 1400°C. According to clause 14,
In the step of manufacturing the liquid and powder paint,
A method of producing hydrophilic enamel for cooking appliances, wherein the frit and hydrophilic crystal mineral are pulverized to 0.1 to 30 ㎛. According to clause 14,
The firing step is,
A method for producing hydrophilic enamel for cooking appliances, carried out at 800 to 900°C.