KR102335867B1 - Organic-inorganic hybrid coating composition applicable on the surface of pottery or porcelain instead of enamel coating and coating method using the same - Google Patents

Abstract

The present invention relates to a hydrophobic ceramic coating paint in which a complex of colloidal silica and (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane and polydimethylsiloxane (PDMS) are homogeneously dispersed in a water-containing solvent, and the same It relates to a coating method of a ceramic or porcelain material cookware using, wherein the paint contains (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane and polydimethylsiloxane 40 to 60, respectively, based on the weight of the total composition It relates to a paint characterized in that it can be fired at 200 to 250° C. including % and 5 to 10% content and its use.

Description

Organic-inorganic hybrid coating composition applicable on the surface of pottery or porcelain instead of enamel coating and coating method using the same

The present invention relates to a hydrophobic ceramic coating paint in which a complex of colloidal silica and (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane and polydimethylsiloxane (PDMS) are homogeneously dispersed in a water-containing solvent, and the same It relates to a coating method of a ceramic or porcelain material cookware using, wherein the paint contains (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane and polydimethylsiloxane 40 to 60, respectively, based on the weight of the total composition It relates to a paint characterized in that it can be fired at 200 to 250° C. including % and 5 to 10% content and its use.

Porcelain containers used for pots, pots, rice cookers, etc. have been widely used in our daily life for a long time.

Porcelain is a compound word of porcelain (陶器) and porcelain (磁器), and refers to a product that is molded with inorganic materials such as clay, feldspar, silica, and ceramics alone or mixed and then hardened by applying heat. The classification of ceramics differs according to countries or scholars, but in Korea, in general, ceramics are broadly divided into four types: porcelain, earthenware, stoneware, and clayware. In the present invention, porcelain is not particularly distinguished by ordinary people, and is often referred to as porcelain. Although it is expressed as porcelain, it should be interpreted to include porcelain in a general sense.

When the glaze layer on the inside of ceramics comes in direct contact with food, food sticks to the surface or it is difficult to clean (adhesiveness). Fluorine resin coating is sometimes used to overcome this point, but in the case of fluororesin coating, the use temperature is low, so the performance deteriorates during long-time cooking and there is a possibility of toxic substances. not great

For example, if there is an unglazed surface, moisture is absorbed into it. When water is absorbed, the boiling time becomes longer when cooking, and energy consumption increases accordingly. In addition to moisture, oil is absorbed or adhered to the surface, making it unsanitary or aesthetically unclean. In addition, the surface to which the glaze is not applied forms an uneven surface as the ceramic particles are exposed as it is, and may cause scratches when these containers are placed on a table or the like.

In general, the manufacturing process of ceramics is generally divided into manufacturing, molding, drying, firing, glazing, vegetarianism, etc. of the base material.

Among them, glazing is performed for the purpose of practical, aesthetic, sanitary and thermal insulation. The main purpose of the glaze is to make it hygienic and convenient to use by applying the glaze to the practical container to increase the strength of the bowl and to remove the peculiar absorbency. In addition, the strength of the glaze is strong so that it can maintain the state of the pottery permanently, so that it can be preserved without changing for a long time. The main components of these glazes are feldspar, silica, and limestone. In particular, silicate is glassy and plays a central role in the glaze, and feldspar acts with the alumina component in the clay to fuse the glaze to the clay, and limestone is the glaze surface. It plays a role in giving gloss and flexibility.

Frit, silica, or silica, which are the main components of the glaze, has a very high melting point of about 1700°C. Considering that conventional earthenware clay is aged at 1000 to 1100° C. and is significantly deformed when calcined at a higher temperature than this, silica stone itself is difficult to use as a glaze component. Therefore, a flux is further included to lower the melting point of the glaze. The glaze composition still used in the presently used tableware requires firing at a high temperature, which requires a lot of energy consumption in the process. On the other hand, in the case of a flux that enables firing at a lower temperature, it contains lead, which can be harmful to the human body, so its use is limited in tableware. It can come out so be careful.

As a result of intensive research efforts to discover a ceramic coating composition applicable to pottery or porcelain by firing at a low temperature, the present inventors used a ceramic coating solution based on colloidal silica and fired at a low temperature of 250° C. or less to form a coating layer Of course, it is possible to improve the compatibility with the added PDMS by adding PDMS to the coating solution to give non-stick performance and using the colloidal silica in the form of a complex with MTES having a hydrophobic methyl group. , the present invention was completed.

As one aspect for achieving the above object, the present invention provides colloidal silica and (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane in a water-containing solvent (wherein n and m are each independently 1 to Provided is a paint for a hydrophobic ceramic coating in which a complex of 3, n+m=4) and polydimethylsiloxane (PDMS) are homogeneously dispersed. In this case, the (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane and polydimethylsiloxane are included in an amount of 40 to 60% and 5 to 10%, respectively, based on the weight of the total composition, and 200 to 250 It is characterized in that it can be fired at °C.

For example, the hydrophobic ceramic coating material is characterized in that it can be applied to pottery or porcelain. As described above, since it can be coated by firing at a low temperature, it does not cause deformation during coating on pottery or porcelain, and provides a non-stick function lacking in these materials. Since coating may be difficult due to the characteristics of ceramics or porcelain due to their rough surface and high roughness, the ceramics and porcelain may be products obtained by sandblasting the surface to be coated.

For example, the (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane is methyltriethoxysilane (MTES), methyltrimethoxysilane (MTMS), dimethyldimethoxysilane; DMDMS), dimethyldiethoxysilane (DMDES), trimethylethoxysilane (TMES), trimethylmethoxysilane (TMMS), or a mixture of two or more selected from them. Specifically, MTES and MEMS may be used in combination, but is not limited thereto.

As used herein, the term "polydimethylsiloxane (PDMS)" is a material having excellent physical properties such as transparency, flexibility, lubricity, and releasability in addition to hydrophobicity, and is a silicone-based polymer suitable for surface-modifying a hydrophilic substrate to be hydrophobic.

For example, PDMS may be a material having a molecular weight exhibiting a viscosity of 80 to 150 cPs, but is not limited thereto.

For example, the paint of the present invention can maintain a uniformly mixed solution state without layer separation due to precipitation or floating of the PDMS component even after 30 minutes have elapsed. The 30 minutes is typically an example of the time required for drying the coating solution during spray coating, and indicates that it is possible to maintain a uniformly mixed solution state without phase separation for a longer period of time, that is, during the entire drying process.

For example, the paint may be in a solution state of pH 4.5 to 5.5. If the pH is less than 4.5, PDMS may not mix in the solution and sink to the bottom due to an incomplete condensation reaction, whereas if the pH exceeds 5.5, PDMS may float to the upper layer due to overgrown growth. Therefore, in order to maintain a uniformly mixed solution state without phase separation, it is preferable to maintain the pH of the solution in the range of 4.5 to 5.5.

_{The complex of colloidal silica and (C 1-4} alkyl) _n (C _1-4 alkoxy) _m silane used in the paint of the present invention is a first solution prepared by dissolving colloidal silica and a prepared acid in a water-containing solvent. step; (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane (wherein n and m are each independently an integer of 1 to 3, n+m=4) and ammonia water in a C _1-4 alcohol solvent A second step of preparing a second solution by dissolving it in; and a third step of slowly pouring the second solution into the first solution to react. The (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane is as defined above.

In this case, the first step and the second step may be performed independently of each other regardless of the order.

For example, the prepared acid is an inorganic acid selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid, or a mixture thereof, and formic acid, acetic acid, propionic acid, phosphoric acid, citric acid ), malic acid, fumaric acid, butyric acid, or a mixture of organic acids selected from the group consisting of mixtures thereof. For example, a mixture of an inorganic acid and an organic acid in a weight ratio of 8:2 to 9.5:0.5 may be used as it is or by dilution, but is not limited thereto.

For example, the first solution may be a solution containing colloidal silica and a water-containing solvent in a weight ratio of (1 to 3):1, and the pH is adjusted to 1.5 to 1.8.

In addition, the second solution includes methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol, and mixtures thereof as a _{C 1-4 alcohol solvent, and the pH is adjusted to 8 to 10 including ammonia.} It may be a solution.

As another aspect, the present invention provides a first step of sandblasting the surface of a cookware made of ceramic or porcelain; a second step of applying the hydrophobic ceramic coating paint to the sandblasted surface obtained from the first step; And it provides a method of manufacturing a ceramic-coated ceramic or porcelain cooking utensil comprising a third step of firing at 200 to 250 ℃.

Since the hydrophobic ceramic coating material of the present invention contains the hydrophobic PDMS in a uniformly mixed state without phase separation, it can be coated on the cooking utensil to prevent burning, that is, non-stick performance. In this case, the second step may be performed by spraying the paint onto the surface to be coated in a solution state, but is not limited thereto, and may be performed using a method known in the art without limitation.

As another aspect, the present invention provides a non-stick pottery or porcelain cooking utensil manufactured by a method, comprising the step of coating the hydrophobic ceramic coating material and firing at a low temperature.

For example, the cooking utensil may be for baking (bakeware) or oven (ovenware).

For example, the cooking utensil of the present invention may include a primer coating layer and a top coating layer additionally introduced on the hydrophobic ceramic coating layer introduced to the surface thereof. The undercoating layer and/or the overcoating layer may be performed using methods known in the art without limitation.

In the paint of the present invention, non-stick performance is imparted by adding PDMS to a ceramic coating solution based on colloidal silica. It is mixed evenly with the ingredients and does not float or spill over time, so an effective hydrophobic coating is possible. can do.

1 is a diagram schematically showing a coating method using a colloidal silica-MTES composite.
2 is a diagram showing the miscibility of PDMS in solution according to the pH of the final solution.
3 is a diagram schematically showing the compatibility of PDMS in a conventional paint containing only colloidal silica and a paint for coating of the present invention containing a colloidal silica-MTES complex.
4 is a view showing the results of observing the particle shape in the solution in each step of the method for manufacturing a paint according to Example 1 of the present invention by TEM.
5 is a view showing the miscibility of each component of the paint prepared according to Example 1 of the present invention was confirmed visually and by SEM-EDS.
6 is a view showing the cross-cut test results of the ceramic cookware and the coating surface before and after coating using the paint prepared according to Example 1 of the present invention.

Hereinafter, the present invention will be described in more detail through examples. These Examples are for explaining the present invention in more detail, and the scope of the present invention is not limited by these Examples.

Example 1: Preparation of a coating material using a colloidal silica-MTES composite

Put 10 g of distilled water in one beaker, and lower the pH to 1.8 by adding 41.4 g of colloidal silica and 17 g of the prepared acid (prepared by diluting 50% of a mixture of formic acid and hydrochloric acid in a weight ratio of 9:1) was ( A1 ). In the other beaker, 106.5 g of isopropyl alcohol (IPA) was added, and 8 g of methyltriethoxysilane (MTES) and 2 g of aqueous ammonia were added to prepare a hydrophobic MTES precursor of pH 10 ( A2 ). The solution A2 was slowly poured into the solution A1 , and a hydrocondensation reaction was performed at room temperature for 14 hours to prepare a silica composite ( A1+A2=A ). 50.1 g of MTMS (methyltrimethoxysilane) and 18.65 g of PDMS (polydimethylsiloxane) ( B ) were added to the prepared silica composite to modify the residual hydroxyl groups on the surface to be hydrophobic, and the final pH was 5 ( A + B ) . The particle shape in each solution was observed by SEM, and the results are shown in FIG. 4 .

Experimental example 1: colloidal silica and of MTES Effect of mixing ratio

In preparing the composition according to Example 1, three compositions having different pH of the final solution were prepared by adjusting the mixing ratio of the acidic colloidal silica solution (A1) and the basic MTES solution (A2). The mixing ratio and thus the pH of the final solution are shown in Table 1 below. Accordingly, the mixing degree of PDMS was changed, and the results were observed in Table 1 and FIG. 2 below. As shown in FIG. 2 , the mixing degree of PDMS was different depending on the pH, which is due to the hydrocondensation reaction. Specifically, at pH 6, PDMS floated on the upper layer due to over-particle growth, while at pH 4, the condensation reaction was insufficient, so PDMS sank to the bottom. It was confirmed that the mixture was evenly mixed without sinking or floating in the middle. This indicates that the pH affects the particle growth rate, that is, the hydrocondensation reaction rate, and the growth of the particles must not be too fast or too slow so that the PDMS can be mixed evenly in the solution.

Colloidal Silica-MTES Mixing Ratio final pH result sample 1 1:1.5 6 PDMS floats up sample 2 1:1.6 5 mix evenly sample 3 1:1.7 4 PDMS sinking down

Experimental example 2: Comparison of structures and properties of paints

3 schematically shows the surface properties and compatibility of each component of the existing paint and the paint (developed paint) including the colloidal silica-MTES composite of Example 1. As shown in FIG. 3 , the conventional paint has hydrophobic properties by reaction with MTMS on the surface of colloidal silica, but the paint including the colloidal silica-MTES composite of Example 1 is a combination of colloidal silica and MTES having different particle sizes. It was confirmed that partial hydrophobicization by a methyl group (-CH ₃ ) and bonding with MTMS were further caused by more hydroxyl groups (-OH), thereby improving compatibility with PDMS. The compatibility with PDMS was confirmed by SEM-EDS, and the results are shown in FIG. 5 . As shown in FIG. 5 , the paint solution maintained the form of an even dispersion without layer separation, and it was confirmed that each component was uniformly mixed in the microstructure.

Example 2: unglazed Ceramic coating and evaluation of properties on pottery

After performing sandblasting on the surface of half of the unglazed ceramic sample, ceramic coating was performed using a paint containing the colloidal silica-MTES composite prepared according to Example 1, and a photograph was taken and shown at the top of FIG. 6 . Specifically, the sample was sandblasted with aluminum oxide #60 to 80 at 2 to 5 MPa on half the surface of the unglazed ceramic sample, and then the colloidal silica-MTES composite prepared according to Example 1 was prepared. Ceramic coating was made on the sandblasted surface of the pottery preheated to 45 to 60°C using

Further, in order to evaluate the adhesion between the ceramic coating layer and the ceramic substrate formed as described above, a cross-cut test (ASTM D3359) was performed, and the results are shown at the bottom of FIG. 6 . As shown at the bottom of FIG. 6 , the surface coated with the paint containing the colloidal silica-MTES composite prepared according to Example 1 showed a clear lattice pattern along the cutting line, and other crushing or peeling did not appear.

Claims (14)

A complex of colloidal silica and (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane in a water-containing solvent, wherein n and m are each independently integers from 1 to 3, and n+m=4 and polydimethylsiloxane (PDMS) as a homogeneously dispersed hydrophobic ceramic coating paint,
The (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane and polydimethylsiloxane are included in an amount of 40 to 60% and 5 to 10%, respectively, based on the weight of the total composition,
It can be fired at 200 to 250 °C,
The complex of colloidal silica with (C _1-4 alkyl) _n (C _1-4 alkoxy) _{m silane is}
A first step of preparing a first solution by dissolving the colloidal silica and the prepared acid in a solvent containing water;
(C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane (wherein n and m are each independently an integer of 1 to 3, n+m=4) and ammonia water in a C _1-4 alcohol solvent A second step of preparing a second solution by dissolving it in; and
Prepared through; a third step of slowly pouring the second solution into the first solution to react;
In the third step, the acidic first solution and the basic second solution are mixed in a ratio of 1:1.6 by weight,
The paint is adjusted so that the pH of the solution mixed in the third step is 4.5 to 5.
The method of claim 1,
A paint that is applicable on pottery or porcelain.
The method of claim 1,
The (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane is methyltriethoxysilane (MTES), methyltrimethoxysilane (MTMS), dimethyldimethoxysilane (DMDMS) , dimethyldiethoxysilane (DMDES), trimethylethoxysilane (TMES) and trimethylmethoxysilane (trimethylmethoxysilane; TMMS) will be at least one material selected from the group consisting of, the paint.
The method of claim 1,
Even after 30 minutes, the PDMS component does not precipitate or float, so that the layer is not separated and the uniformly mixed solution is maintained.
delete delete The method of claim 1,
The first step and the second step will be performed independently of each other regardless of the order, the paint.
The method of claim 1,
The prepared acid is an inorganic acid selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid, or mixtures thereof, and formic acid, acetic acid, propionic acid, phosphoric acid, citric acid, The paint, which is a mixture of organic acids selected from the group consisting of malic acid, fumaric acid, butyric acid, or mixtures thereof.
The method of claim 1,
The first solution contains colloidal silica and a water-containing solvent in a weight ratio of (1 to 3): 1, and the pH is adjusted to 1.5 to 1.8.
The method of claim 1,
The second solution includes methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol, and mixtures thereof as a _{C 1-4 alcohol solvent,}
The paint, which is a solution whose pH is adjusted to 8 to 10, including ammonia.
A first step of sandblasting the surface of the pottery or porcelain cookware;
A second step of applying the paint of any one of claims 1 to 4 on the sandblasted surface obtained from the first step; and
A method of manufacturing a cookware made of a ceramic or porcelain material coated with hydrophobic ceramics, comprising a third step of firing at 200 to 250°C.
A non-stick ceramic or porcelain cooking utensil comprising a hydrophobic ceramic coating layer manufactured by the method of claim 11 .
12. The method of claim 11,
A cooking utensil for use in baking or ovens.
12. The method of claim 11,
The cooking utensil that further comprises a primer coating layer and a top coating layer introduced on the hydrophobic ceramic coating layer.

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