KR20210046813A - Paint for hydrophobic ceramic coating with improved miscibility - Google Patents

Abstract

The present invention is a coating material for a hydrophobic ceramic coating 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.} It relates to a manufacturing method and a non-stick cookware coated therewith.

Description

Paint for hydrophobic ceramic coating with improved miscibility

The present invention is a coating material for a hydrophobic ceramic coating 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.} It relates to a manufacturing method and a non-stick cookware coated therewith.

Kitchen utensils such as frying pans and pots have been mainly manufactured using materials such as general steel, aluminum alloy, aluminum plate, and stainless steel. In particular, aluminum materials that are lightweight, easy to form, and inexpensive to manufacture are often used.

However, devices made of these materials have many problems, such as repeated expansion and contraction of metal by repeated rapid heating and rapid cooling, damage to the coating surface due to consumer negligence, and oxidation, peeling, and corrosion. In particular, the coating is peeled off for the above reasons to expose metal components such as aluminum, and food is pressed on the part where the coating is peeled, and the substrate is corroded by the acid component of the cooked food. It has been reported that it can accumulate and cause side effects such as Alzheimer's disease.

Therefore, it is preferable that the kitchen utensils can withstand high cooking temperatures, have corrosion resistance and peel resistance that are strong against surface abrasion and scratches, and have non-adhesiveness in which food does not stick.

To this end, in the cook-ware field, a fine ceramic coating is applied to the metal surface of the product using inorganic paints and inorganic ceramic coating compositions having properties such as excellent heat resistance, weather resistance, stain resistance, chemical resistance, and durability. A technology for preventing metal corrosion of household kitchen utensils has been used.

Meanwhile, ceramics traditionally use natural raw materials such as clay, and have been used as containers (pottery). Recently, it is a general term for products heat-treated using high-purity artificial inorganic materials such as glass and metal oxides, and to distinguish them from ceramics, they are referred to as fine ceramics.

Ceramic coating is a fine ceramic with strong corrosion resistance, heat resistance, and abrasion resistance, which coats a coating on the product surface.In household kitchen utensils, the above ceramic coating is mainly applied to cooking containers to prevent corrosion of metal and prevent food from sticking during cooking. have.

Ceramic-coated kitchen containers are capable of implementing a variety of colors that are difficult to express with other coatings such as fluorine coating, and the coating does not peel off or burn even at temperatures above 350℃. Nevertheless, it is being neglected by consumers in that it is relatively easy to peel off due to its short persistence of food nonstick (nonstick) and weak properties to impact.

When cooking food, the technology applied to cookware products where peeling durability and non-stick function are the most important is a fluorine coating method based on polytetrafluoroethylene (PTFE, Teflon), which is harmful to the human body (US Environmental Protection Agency EPA, 2005). Official announcement) and gel-casting eco-friendly ceramic coating methods are mainly used.

The thermal stability of the coating material for cooking utensils is an important performance index that can prevent the phenomenon of shortening the life of the cooking utensils due to thermal decomposition of the coating material that may occur during heat cooking or the phenomenon that the thermally decomposed material is migrated to food. PTFE-based coatings represented by Teflon (Dupont Co.) are most commonly used for non-stick coatings, but the thermal decomposition temperature is around 200°C, so in a cooking environment using meat or oil cooked at 230 to 260°C, it is not harmful to the human body. May release harmful toxic substances.

On the other hand, the gel casting method is the most economical method among several methods of molding fine ceramics. When mixed with ceramic powder, organic additives in the ceramic mixture solution are maintained in a monomer state, resulting in low viscosity, and a reaction catalyst is used during molding. It is a method of obtaining a high-viscosity molded article according to the formation of a mold by adding to form a polymer network having a network structure. At this time, the transition time from the sol state to the gel state can be relatively easily controlled by controlling the type of monomer and/or cross-linker, the amount and type of reaction catalyst, and the amount of distilled water.

Nevertheless, the current ceramic coating method has excellent performance in all respects. However, when applied to kitchen utensils, as the number of uses increases, the persistence of the non-stick performance becomes shorter and peeling occurs relatively frequently due to weak impact. have. In other words, fluorine coating products that can generate harmful substances to the human body due to lack of non-stick performance and peeling prevention function occupy 80% of the domestic cookware coating market. To overcome this, non-stick performance is improved by introducing silicon having a hydrophobic methyl group (-CH ₃ ) on the ceramic coating, but it is still insufficient to replace the conventional fluorine coating (friction coefficient: Teflon 0.05 to 0.1, silicon 0.3 to 0.8). As such, there are no companies in the world that have commercialized non-stick and peel-resistant ceramic coating methods at the level of fluorine coating.

In providing a coating material for coating containing a hydrophobic material in order to impart non-stick performance to the cooking utensils, colloidal silica

One object of the present invention is colloidal silica and (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane in a water-containing solvent (where n and m are each independently an integer of 1 to 3, n+ m = 4) composite and polydimethylsiloxane (PDMS) are homogeneously dispersed in a coating for a hydrophobic ceramic coating.

Another object of the present invention is a first step of preparing a first solution by dissolving colloidal silica and a prepared acid in a water-containing solvent; (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane (where n and m are each independently integers of 1 to 3, n+m=4) and ammonia solution to C ₁ A second step of preparing a second solution by dissolving in _{-4 alcohol solvent;} A third step of gradually pouring a second solution into the first solution to react; And a fourth step of adding methyltrimethoxysilane (MTMS) and polydimethylsiloxane (PDMS) to the reaction solution obtained from the previous step.

Another object of the present invention is the It is to provide a method of manufacturing a non-stick cookware comprising the step of coating a coating material on the surface.

The paint of the present invention imparts non-stick performance by adding PDMS to a ceramic coating solution based on colloidal silica, but by using the colloidal silica in the form of a composite with MTES having a hydrophobic methyl group, the PDMS added thereto is another component in the paint. Since it is evenly mixed with the field and does not float or spill over time, effective hydrophobic coating is possible, and bubbles can be formed on the surface of the coating layer due to floating and loss of PDMS, thereby forming an even and smooth surface. .

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 a solution according to the pH of the final solution.
3 is a diagram showing the degree of separation of PDMS from paint over time. Specifically, this is a photograph taken after leaving the existing paint (Comparative Example 1) and the paint of the present invention (Example 1) for 30 minutes, which is the time required for drying after applying the paint during normal coating.
4 is a diagram schematically showing the miscibility of PDMS in a conventional coating containing only colloidal silica and a coating for coating of the present invention containing a colloidal silica-MTES composite.
5 is a diagram showing a result of observing a particle shape in a solution by TEM in each step of the coating material manufacturing method according to Example 1 of the present invention.
6 is a diagram showing the compatibility of each component of the paint prepared according to Example 1 of the present invention visually and by confirming with SEM-EDS.
7 is a view showing the degree of precipitation confirmed by confirming the miscibility according to the PDMS ratio in the paint prepared according to Example 1 of the present invention.

Best mode for carrying out the invention

As one aspect for achieving the above object, the present invention is a water-containing solvent with colloidal silica and (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane (here, n and m are each independently 1 to It is an integer of 3, and n+m=4) composite and polydimethylsiloxane (PDMS) are homogeneously dispersed in a hydrophobic ceramic coating coating.

For example, the (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane may include methyltriethoxysilane (MTES), methyltrimethoxysilane (MTMS), dimethyldimethoxysilane; DMDMS), dimethyldiethoxysilane (DMDES), trimethylethoxysilane (TMES) trimethylmethoxysilane (TMMS), or a mixture thereof, but is not limited thereto. Specifically, MTES may be used, but is not limited thereto.

The present invention is designed to discover a coating solution capable of exhibiting non-stick performance by adding PDMS to a coating material for ceramic coating based on colloidal silica to impart hydrophobicity. Specifically, in the case of a simple mixture of conventional colloidal silica and PDMS, it is difficult to obtain the desired non-stick performance as the PDMS floats to the upper layer and detaches over time during coating and drying on a substrate. In order to solve the problem of causing corrosion of the substrate through the formation of air bubbles, oxygen, moisture, etc. penetrate through it, and colloidal silica is mixed with ammonia water and hydrophobized alkylalkoxysilane through a hydrocondensation reaction to form a complex. It is a feature of the present invention that by adding PDMS and MTMS, the miscibility between these components is improved, so that even over time, PDMS is separated from other components and is not suspended in the upper layer and can maintain a uniform dispersion form. . In particular, in order to form such a uniform mixed solution, pH adjustment must be accompanied, and by optimizing such conditions, a coating material containing PDMS in a ratio of at most 1:1 for colloidal silica-MTES composites can be provided.

For example, the coating material of the present invention can maintain a uniformly mixed solution state without sedimentation or suspension of PDMS components even after 30 minutes elapsed. The 30 minutes typically exemplifies the time required for drying of the coating solution during spray coating, and indicates that a uniformly mixed solution state can be maintained without phase separation for a longer period of time, that is, during the entire drying process.

For example, in the coating material of the present invention, _{the content ratio of polydimethylsiloxane to the colloidal silica and (C 1-4} alkyl) _n (C _1-4 alkoxy) _m silane complex may be 10:90 to 50:50. The "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 modification of a hydrophilic substrate with hydrophobicity.

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

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 be mixed in the solution due to an incomplete condensation reaction and may sink to the bottom, whereas if the pH exceeds 5.5, PDMS may float to the upper layer due to overparticle 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.

In another aspect, the present invention provides a first step of preparing a first solution by dissolving colloidal silica and a prepared acid in a water-containing solvent; (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane (where n is 1 or 2, m is 2 or 3, and n+m=4) and aqueous ammonia in a C _1-4 alcohol solvent A second step of preparing a second solution by dissolving; A third step of gradually pouring a second solution into the first solution to react; And a fourth step of adding methyltrimethoxysilane (MTMS) and polydimethylsiloxane (PDMS) to the reaction solution obtained from the previous step. Provides a way.

The (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane is as defined above.

For example, the preparation acid may be an acidic solution prepared by mixing an inorganic acid and an organic acid in a predetermined ratio. Inorganic acids used in the preparation acid are hydrochloric acid, nitric acid, sulfuric acid, or a mixture thereof, and organic acids are formic acid, acetic acid, propionic acid, phosphoric acid, citric acid, It may be malic acid, fumaric acid, butyric acid, or a mixture thereof, but is not limited thereto. For example, an inorganic acid and an organic acid may be mixed in a weight ratio of 8:2 to 9.5:0.5, and may be used as it is or diluted, but is not limited thereto.

For example, the C _1-4 alcohol used in the second solution may be methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol, or a mixture thereof. Specifically, the C _1-4 alcohol may be isopropyl alcohol, but is not limited thereto.

For example, the first step and the second step are marked with a random number for convenience, and can be performed independently of each other regardless of the order.

For example, the first solution may be acidic with a pH of 1 to 2.

Meanwhile, the second solution may have a basic pH of 8 to 10.

On the other hand, as described above, since the miscibility of PDMS may change depending on the pH of the prepared paint, a step of adjusting the pH of the solution obtained from the fourth step to 4.5 to 5.5 may be additionally performed, but is limited thereto. It doesn't work.

As another aspect, the present invention It provides a method of manufacturing a non-stick cookware comprising the step of coating a coating material on the surface.

Since the coating material for coating of the present invention contains hydrophobic PDMS in a uniformly mixed state without phase separation, it can be coated on cookware to prevent crushing, that is, impart non-stick performance. At this time, the method of coating the cooking utensils may be a spray coating method in which the paint is sprayed on the surface to be coated in a solution state and then dried to form a coating layer, but is not limited thereto, and a coating method known in the art Can be performed using without limitation.

Mode for carrying out the invention

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

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

10 g of distilled water was added to one beaker, and 41.4 g of colloidal silica and 17 g of preparative acid (prepared by diluting 50% of formic acid and hydrochloric acid in a weight ratio of 9:1) were added to lower the pH to 1.8 ( A1 ). In the other beaker, 106.5 g of isopropyl alcohol (IPA) was added, and 8 g of methyltriethoxysilane (MTES) and 2 g of ammonia water were added to prepare a hydrophobic MTES precursor having a pH of 10 ( A2 ). The solution 2 was slowly poured into solution 1 to perform a hydrocondensation reaction 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 hydrophobically modify the remaining hydroxyl groups on the surface and the final pH was 5 ( A+B ). . The particle morphology in each solution was observed by SEM, and the results are shown in FIG. 5.

Comparative Example 1: Preparation of a conventional four-component coating material using colloidal silica

After adding an acid catalyst ( A2' ) to a solution (A1' ) in which colloidal silica was dispersed in water, MTMS, PDMS ( B ), and a base catalyst ( C ) were sequentially added to the mixed solution.

Experimental Example 1: Effect of the mixing ratio of colloidal silica and MTES

The pH of the mixed final solution of basic MTES was adjusted by adjusting the amount of the prepared acid in the acidic colloidal silica solution. 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, whereas at pH 4, the condensation reaction was insufficient and PDMS sank at the bottom. At pH 5, the reaction occurred at an appropriate rate and PDMS was dissolved in a solution. It was confirmed that it was mixed evenly without sinking or floating in it. This indicates that the pH affects the particle growth rate, that is, the hydrocondensation reaction rate, and the PDMS can be evenly mixed in the solution when the growth of the particles is not too fast or slow.

Manufacturing production consumption Final pH result Sample 1 10 g 6 PDMS floats up Sample 2 17 g 5 Evenly mixed Sample 3 20 g 4 PDMS sinks down

Experimental Example 2: Comparison of PDMS separation degree of paint over time

Considering that the time required for drying after applying the paint in a typical spray coating process is about 30 minutes, in order to confirm whether the PDMS in the paint component floats and separates in the coating liquid during that time, Example 1 and Comparative Example 1 After the coating solution prepared according to was left for 30 minutes, the layer separation was visually confirmed, and the results are shown in FIG. 3. As shown in FIG. 3, it was confirmed that the existing paint of Comparative Example 1 was layer-separated due to the floating PDMS, but the paint of the present invention of Example 1 was still evenly mixed with PDMS in the solution even after 30 minutes elapsed.

Experimental Example 3: Comparison of structure and physical properties of paint

FIG. 4 schematically shows the surface characteristics and miscibility of each component of the conventional coating of Comparative Example 1 and the coating including the colloidal silica-MTES composite of Example 1. FIG. As shown in FIG. 4, the conventional paint became hydrophobic through the hydrocondensation reaction of colloidal silica particles and MTMS, but the miscibility with PDMS was poor, and as time passed, PDMS floated on the top and evaporated to generate pinholes. The paint of Example 1 using MTES as a starting material had more hydrophobicity than the paint of Comparative Example 1, and thus was uniformly mixed with PDMS. In each step of the manufacturing method according to Example 1, the shape of each particle in the solution was observed and shown in FIG. 5, and in FIG. 6, uniform mixing with PDMS in the final prepared paint, confirmed by SEM-EDS, was shown. As shown in FIG. 6, it was confirmed that the coating solution maintained an even dispersion without layer separation, and that each component was uniformly mixed even in a microstructure.

Experimental Example 4: Comparison of the maximum amount of PDMS added to the coating material according to the use of the colloidal silica-MTES composite

As confirmed in Experimental Example 3, in order to confirm the maximum content of PDMS that can be uniformly mixed in the paint of Example 1 with increased miscibility with PDMS, colloidal silica-MTES was mixed while increasing the amount of PDMS, and uniform Whether or not it was maintained as a dispersion was visually checked, and the results are shown in Table 2 and FIG. 7 below. As shown in FIG. 7, when the PDMS content was 20% and 40%, respectively, it was uniformly mixed and dispersed without precipitation, but when the PDMS content was increased to 60 and 70%, respectively, it was gradually precipitated, and PDMS 80% In the case of, it was confirmed that it was hardly mixed and precipitated.

Mixing ratio (weight ratio) 2:8 3:7 4:6 6:4 8:2 Colloidal Silica-MTES:PDMS Sedimentation Slowly settle Slowly settle Uniform mixing Uniform mixing

Claims (14)

Complex of colloidal silica and (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane in a water-containing solvent (where n and m are each independently integers of 1 to 3, n+m=4) And polydimethylsiloxane (PDMS) homogeneously dispersed hydrophobic ceramic coating paint. The method of claim 1,
The (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane is methyltriethoxysilane (MTES), methyltrimethoxysilane (MTMS), and dimethyldimethoxysilane (DMDMS). , Dimethyldiethoxysilane (DMDES), trimethylethoxysilane (TMES), and trimethylmethoxysilane (TMMS) is one or more materials selected from the group consisting of, the paint. The method of claim 1,
Even after 30 minutes, the PDMS component is not precipitated or floated to separate layers and maintains a uniformly mixed solution state. The method of claim 1,
The content ratio of the polydimethylsiloxane to the colloidal silica and (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane complex is 10:90 to 50:50, the coating. The method of claim 1,
The paint that the pH is 4.5 to 5.5. A first step of preparing a first solution by dissolving colloidal silica and a prepared acid in a water-containing solvent;
(C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane (where n and m are each independently an integer of 1 to 3, n+m=4) and aqueous ammonia as a C _1-4 alcohol solvent A second step of preparing a second solution by dissolving in it;
A third step of gradually pouring a second solution into the first solution to react; And
A method for preparing a coating for hydrophobic ceramic coating with improved miscibility, comprising a fourth step of adding methyltrimethoxysilane (MTMS) and polydimethylsiloxane (PDMS) to the reaction solution obtained from the previous step . The method of claim 6,
The first step and the second step is to be performed independently of each other regardless of the order, the manufacturing method. The method of claim 6,
The (C _1-4 alkyl) _n (C _1-4 alkoxy) _m silane is methyltriethoxysilane (MTES), methyltrimethoxysilane (MTMS), and dimethyldimethoxysilane (DMDMS). , Dimethyldiethoxysilane (DMDES), trimethylethoxysilane (TMES), and trimethylmethoxysilane (TMMS) is one or more materials selected from the group consisting of. The method of claim 6,
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, It 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 6,
The C _1-4 alcohol is selected from the group consisting of methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol, and mixtures thereof. The method of claim 6,
The first solution will be acidic with a pH of 1 to 2, the manufacturing method. The method of claim 6,
The second solution is a basic pH of 8 to 10, the manufacturing method. The method of claim 6,
The method further comprising the step of adjusting the pH of the solution obtained from the fourth step to 4.5 to 5.5. A method of manufacturing a non-stick cookware comprising the step of coating the surface of the coating material for coating of claim 1.

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