JP2018020314A - Surface-coating method for presenting solid pattern texture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating method for forming a solid pattern on a heater surface such as a kitchen apparatus only by coating.SOLUTION: A coating method includes forming an undercoat layer by coating and drying polytetrafluoroethylene, N-methyl-2-pyrolidone, water, a dispersant, a polyether sulfone, a polyamide imide, an inorganic pigment, AlO, SiC, silica sol, and a diacetone alcohol mixture, forming an intermediate coat layer by coating polytetrafluoroethylene, a water-soluble acrylic resin, water, a dimethylamino ethanol, a pearl pigment, a perfluoro alkoxy resin, an acrylic dispersant, a dispersant, a thickener, ethylene glycol mono-butyl ether, and an inorganic pigment mixture on the undercoat layer, and forming a top coat layer by heating and drying by wet-on-wet coating of polytetrafluoroethylene, a water-soluble acrylic resin, water, dimethylamino ethanol, the pearl pigment, a perfluoro alkoxy resin, triethanolamine, and a dispersant mixture on the intermediate coat layer.SELECTED DRAWING: Figure 2

Description

  The present invention provides a surface coating method that sequentially performs primer coating, mid coating, and top coating on a surface of a kitchen appliance or the like to exhibit a three-dimensional pattern texture. About.

  Generally, kitchen utensils are utensils for cooking food such as frying pans and pans, and the rough surface is cut or ground to prevent food from burning, and at the same time, phenomena such as scratches due to external contact are caused. Apply coating to prevent it.

  The coating process can usually proceed by methods such as undercoating, intermediate coating, and topcoating, and can be performed with materials such as fluororesin coating, ceramic coating, tepron coating, and titanium coating. Typically, a method of coating a fluorine resin paint typified by polytetrafluoroethylene (PTFE) on the inner surface of a device that comes into contact with food is often used.

  Fluororesin has excellent non-adhesiveness and chemical resistance and is often used as a coating material for kitchen appliances. In addition, as a method of coating a fluororesin on a metal substrate of a kitchen appliance, a primer coating is performed on a substrate that has been subjected to surface roughening treatment by a method such as blasting, and a primer coating is applied. After firmly adhering first, a fluororesin is bound to the undercoat paint, or fine irregularities are formed on the surface of the base material, and the fluororesin is infiltrated into the irregularities thus formed. A method of physically bonding is used.

  In addition, methods for applying undercoating, intermediate coating, and overcoating on the surface of equipment have been standardized, and as such a coating method, after undercoating, intermediate coating is applied in low-viscosity black, silver, or various colors. After coating with a paint or undercoating, make a pattern using silk printing, spray coat with an intermediate coating, and then apply a top coating to express various colors and create a pattern on the surface.

  However, when the intermediate coating is performed with the conventional paint as described above, a three-dimensional pattern is not formed on the surface of the container, and a planar coating film is formed. When unevenness is given, the surface is rough and cracks are likely to occur, so there are disadvantages in that wear resistance and corrosion resistance are weak.

  In addition, in order to express various colors and patterns, conventional fluororesin paints can be screen-printed by topcoat coating after undercoating, or various colors can be added to intermediate coatings. In this case, the dry coating film is rough, the work process time is long, many spray guns are required, and the thickness of the coating film is difficult to adjust. is there.

  The other conventional methods have a long work process time, and thus the loss of paint is large at the time of work, and it is impossible to make a certain three-dimensional pattern or smooth the uneven coating film surface.

  In order to solve such a problem, Patent Document 1 (Korean Utility Model Registration No. 20-0347043) discloses that a one-coating layer is formed by applying a ceramic paint, a heat-resistant paint, or a fluororesin paint to the surface of an instrument. An invention is disclosed in which a discontinuous coating layer having irregular irregularities is formed on the surface by forming an ink pigment on the surface and forming a discontinuous coating layer on the surface.

  According to the above publication, the discontinuous coating layer of the ink pigment applied in the form of spots protrudes toward the upper part, the scratch phenomenon does not occur, the surface area in contact with food is relatively increased by the protrusion, and heat transfer is increased. It is performed uniformly, and the effect that the gloss effect is exhibited by the discontinuous coating layer can be obtained.

  However, the ink pigment applied in the form of spots is bound non-continuously with the one coating layer, and the binding force between the ink pigment and the one coating layer is not sufficient. When it comes off, the problem of mixing into food occurs, and the ink pigment is applied in the form of spots, so that it is difficult to form various patterns, and in particular, it is difficult to express a three-dimensional pattern.

  Thus, Patent Document 2 (Korea Patent No. 10-138576) discloses a method of forming a three-dimensional pattern on the bottom of a kitchen container using an electromagnet module and a magnetic coating agent. The magnetic coating agent is applied to the bottom of the container, the magnetic coating agent is aggregated in a specific pattern by selectively applying power to the electromagnet module to form a magnetic field, and this is left to stand for a certain period of time, and then fired. A three-dimensional pattern is formed on the bottom of the kitchen container.

  According to the above method, a three-dimensional pattern can be easily and precisely formed, the pattern and thickness can be adjusted, and the process time can be shortened. However, the coating agent is bonded to the bottom surface of the kitchen container by baking. Therefore, the coating agent is easily detached from the kitchen container in a high temperature cooking process, and the magnetic material is coated by baking, so that the surface is rough, cracks are easily generated, and the wear resistance and corrosion resistance are weak.

Korean Utility Model Registration No. 20-0347043 Korean Patent No. 10-138576

  The present invention is for solving the above-described problems, and the coated film is firmly bonded to the surface of the appliance while forming a three-dimensional pattern only on the surface of the heating appliance such as a kitchen appliance. A surface coating method is provided that exhibits a three-dimensional texture that prevents the food from being burnt on the coating formed by the coating during the cooking process of the food.

  In order to solve the above-mentioned problems, the present invention provides a polytetrafluoroethylene paste (solid content: 50 wt% to 60 wt%), 100 wt parts, N-methyl-2-pyrrolidone, 10 wt parts to 20 wt parts, water 70 parts by weight to 85 parts by weight, 10 parts by weight to 20 parts by weight of a dispersant, 80 parts by weight to 100 parts by weight of a polyethersulfone paste (solid content 13% by weight to 30% by weight), a polyamideimide paste (solids content 13) 80 to 100 parts by weight, inorganic pigments 1 to 5 parts by weight, aluminum oxide 25 to 35 parts by weight, silicon carbide 10 to 20 parts by weight, silica sol (solid content) 25 wt% to 35 wt%) 10 parts by weight to 20 parts by weight, and 5 parts by weight to 10 parts by weight of diacetone alcohol to mix the primer coating composition Preparing; coating the primer coating composition on the surface of a kitchen appliance at a pressure of 100 kPa to 500 kPa and drying at 50 ° C. to 280 ° C. for 5 minutes to 30 minutes to form a primer coating layer; polytetrafluoro 100 parts by weight of ethylene paste (solid content: 50% to 60% by weight), 10 parts by weight to 20 parts by weight of water-soluble acrylic resin, 25 parts by weight to 35 parts by weight of water, 1 part by weight to 5 parts by weight of dimethylaminoethanol Pearl pigment 0.5 parts by weight to 5.0 parts by weight, perfluoroalkoxy resin (solid content 20% by weight to 50% by weight) 20 parts by weight to 30 parts by weight, acrylic dispersant 5 parts by weight to 15 parts by weight, 2 to 6 parts by weight of a dispersant, 4 to 7 parts by weight of a thickener, 4 to 8 parts by weight of ethylene glycol monobutyl ether, Preparing an intermediate coating composition by mixing 2 parts by weight to 5 parts by weight of an inorganic pigment; coating the intermediate coating composition on the dried primer coating layer at a pressure of 10 kPa to 300 kPa Step of forming an intermediate coating layer: 100 parts by weight of polytetrafluoroethylene paste (solid content: 50% to 60% by weight), 7 parts by weight to 13 parts by weight of water-soluble acrylic resin, 30 parts by weight to 50 parts by weight of water Parts, dimethylaminoethanol 1 part by weight to 5 parts by weight, pearl pigment 0.05 parts by weight to 0.5 parts by weight, perfluoroalkoxy resin (solid content 20% to 50% by weight) 25 parts by weight to 35 parts by weight By mixing 2 to 6 parts by weight of triethanolamine and 5 to 10 parts by weight of a dispersant. Preparing a coating composition; and coating the top coating composition on the intermediate coating layer at a pressure of 100 kPa to 500 kPa in a wet-on-wet manner at 350 ° C. to 450 ° C. for 5 minutes to 50 minutes. A method of surface coating showing a three-dimensional pattern texture comprising: forming an overcoating layer by drying.

  The coating method according to the present invention can express various colors and three-dimensional textures on the surface of the kitchen appliance with a simple work process, is excellent in corrosion resistance and wear resistance, and the coating film is formed on the surface of the kitchen appliance. Since it is firmly bonded and difficult to peel off, the original coating performance can be maintained even after long-term use, it has excellent mold release properties, and food does not burn on the coating film during the cooking process.

It is sectional drawing which shows a mode that the coating film coated by the method of this invention shows a three-dimensional pattern texture. It is the theoretical illustration figure which shows a mode that the coating layer coated with the method of this invention shows a three-dimensional pattern texture. It is the elements on larger scale which show the three-dimensional pattern texture of the surface of the kitchen appliance coated by the method of this invention.

  The present invention provides a primer coating, an intermediate coating, and a top coating composition mainly composed of polytetrafluoroethylene in order to show various three-dimensional pattern textures on the surface of a kitchen appliance, and a process of coating the kitchen appliance with the composition. Consists of.

  Specifically, a high-viscosity composition showing a three-dimensional pattern texture on the undercoat coating layer after being undercoated with a low-viscosity composition excellent in binding force with the surface of the kitchen appliance and the intermediate coating layer. A low-viscosity composition excellent in binding strength with the intermediate coating layer and excellent in non-stick on the coating surface is applied to the intermediate coating layer and wet-on-wet (wet). -On-wet) coating method, the coating film shows excellent corrosion resistance and abrasion resistance, expresses a three-dimensional pattern texture on the surface of the kitchen utensil, and is excellent in releasability. Provides the effect that the food does not burn on the surface of the kitchen utensil.

  First, an undercoat coating composition for forming an undercoat coating layer is prepared.

The undercoat coating composition is composed of 100 parts by weight of polytetrafluoroethylene paste (solid content: 50% to 60% by weight), 10% by weight of N-methyl-2-pyrrolidone (NMP) solvent. Parts to 20 parts by weight, pure water 70 parts to 85 parts by weight, dispersant 10 parts to 20 parts by weight, polyethersulfone (polyester sulfone, PES) paste (solid content 13% to 30% by weight) 80% Parts to 100 parts by weight, polyamidoimide (PAI) paste (solid content 13 wt% to 30 wt%) 80 parts to 100 parts by weight, inorganic pigment 1 part to 5 parts by weight, aluminum oxide (Al ₂ O ₃₎ 25 parts by weight to 35 parts by weight of silicon carbide (SiC) 10 parts by weight to 0 parts by weight, 10 parts by weight to 20 parts by weight of silica sol (solid content 25% to 35% by weight) and 5 parts by weight of diacetone alcohol (4-Hydroxy-4-methyl-2-pentaneone, diacetone alcohol, DAA) -10 parts by weight.

  The undercoat coating is performed on the surface of the kitchen appliance using a general spray at a pressure of 100 kPa to 500 kPa, and after the undercoat coating, is dried at 50 ° C. to 280 ° C. for 5 minutes to 30 minutes to form the undercoat coating layer. It is preferable that the thickness of the dry coating film has a range of 10 μm to 100 μm.

  The intermediate coating composition is composed of 100 parts by weight of polytetrafluoroethylene paste (solid content: 50% to 60% by weight), 10 parts by weight to 20 parts by weight of water-soluble acrylic resin, pure water 25 to 35 parts by weight, dimethylaminoethanol (DMAE) 1 to 5 parts by weight, pearl pigment (pearl pigment) 0.5 to 5.0 parts by weight, perfluoroalkoxy (PFA) 20 to 30 parts by weight of resin (solid content 20% to 50% by weight), 5 to 15 parts by weight of acrylic dispersant, 2 to 6 parts by weight of dispersant, 4 to 7 parts by weight of thickener Parts by weight, ethylene glycol monobutyl ether (et ylene glycol monobutyl ether, EGBE) containing 4 parts by weight to 8 parts by weight, and the inorganic pigment 2 parts by weight to 5 parts by weight.

  The intermediate coating is performed at a pressure of 10 kPa to 300 kPa using a low pressure spray on the dried primer coating layer, and the coating thickness of the intermediate coating layer formed by the intermediate coating is in the range of 30 μm to 300 μm. It is preferable to have.

  The top coating composition is composed of 100 parts by weight of polytetrafluoroethylene paste (solid content: 50 to 60% by weight), 7 to 13 parts by weight of water-soluble acrylic resin, and 30 to 50 parts by weight of pure water. Dimethylaminoethanol 1 part by weight to 5 parts by weight, pearl pigment 0.05 part by weight to 0.50 part by weight, perfluoroalkoxy resin (solid content 20% by weight to 50% by weight) 25 parts by weight to 35 parts by weight, It contains 2 to 6 parts by weight of triethanolamine (TEA) and 5 to 10 parts by weight of a dispersant.

  The top coat is formed on the intermediate coat layer using a general spray and wet-on-wet method at a pressure of 100 kPa to 500 kPa, then dried at 350 ° C. to 450 ° C. for 5 minutes to 50 minutes, and formed by top coat coating The thickness of the dried coating film of the overcoating layer to be formed preferably has a range of 10 μm to 100 μm.

  As described above, the adhesion and abrasion resistance of the coating are increased by drying at a high temperature after the final coating, but the final drying temperature is less than 380 ° C. or the drying time is less than 5 minutes. In the case where the adhesion and bonding strength between the surface of the kitchen utensil, the undercoat coating layer and each coating layer are low, and the drying temperature exceeds 450 ° C. or the drying time exceeds 50 minutes, the corrosion resistance and abrasion resistance of the coating film There is a problem that the wear and release properties are lowered, and the three-dimensional effect of the handle formed on the surface of the kitchen appliance is lowered.

  The viscosity of each coating composition is controlled by the content of the solvent and pure water used in the primer coating composition, the pure water used in the intermediate coating and the top coating composition, and the primer coating and the top coating composition. Increases the solvent / pure water content ratio and keeps the viscosity low, while the intermediate coating composition keeps the pure water content ratio low and the viscosity high.

  Therefore, the low-viscosity primer coating composition is sprayed at high pressure on the surface of the kitchen appliance to form a uniform and thin primer coating layer while being uniformly diffused, on which the high-viscosity intermediate coating composition is applied at low pressure. A thick intermediate coating layer is formed while being sprayed and irregularly and intermittently laminated, and a low-viscosity overcoating composition is again sprayed at a high pressure on the coating coating while being thinly covered with a constant thickness. A film is formed.

  As described above, by adjusting the viscosity of each coating composition, the primer coating layer is attached to the surface of the kitchen appliance with a small thickness, and the intermediate coating layer is formed on the kitchen appliance via the primer coating layer. Firmly bind to the surface. In addition, the intermediate coating layer is formed with a thick thickness while the surface is uneven, so that the coating film shows a three-dimensional texture, and the top coating layer consists of the intermediate coating layer and the wet-on-wet system. It is coated with a certain thin thickness, and it shows the uneven shape of the intermediate coating layer as it is while firmly bound.

  1 to 3 show a state of a coating film coated on the surface of a kitchen appliance by the method of the present invention. Referring to FIG. 1, a primer coating layer 2 is formed on the base material layer 1 of the kitchen appliance in a thin and constant thickness, and an intermediate coating layer 3 is formed irregularly thick on the primer coating layer 2. However, in the intermediate coating layer 3, the intermediate coating composition having a high viscosity is sprayed at a low pressure, and the composition is irregularly laminated as shown in FIG. The top coating layer 4 is formed thin and at a constant thickness on the top of the coating layer 3, and the uneven shape of the top surface of the intermediate coating layer 3 is formed as it is on the surface of the top coating layer 4. As a result, as shown in FIG. 3, a coating film in which a three-dimensional pattern texture is expressed on the surface of the kitchen appliance is formed.

  When food is cooked with a coating film with irregularities as described above, the food is shrunk while the moisture of the food is removed by cooking heat, and the food comes into contact only with the protruding part of the coating film, resulting in a decrease in the contact surface The effect makes it easier for food to leave without scorching the coating.

  The viscosity of the undercoat coating composition and the topcoat coating composition is preferably a low viscosity that takes 8 to 15 seconds to be discharged from the Zahn Cup # 3, and the viscosity of the intermediate coating composition is A high viscosity of 50000 cP to 100000 cP (centipoise) is preferable.

  The polytetrafluoroethylene resin used as the main material of the coating composition used in the present invention has excellent chemical resistance, is stable even at high temperatures, has excellent releasability, and is often used as a coating material for kitchen appliances. Has been.

  The polyethersulfone resin and polyamideimide resin used in the undercoat coating composition serve to improve wear resistance at high temperatures and increase the thermal stability of the polytetrafluoroethylene resin. Is an amorphous, aromatic resin with excellent heat resistance, hot water resistance, steam resistance, flame retardancy and chemical resistance. Polyamideimide resin is heat resistant, wear resistant, mechanical, chemical, Excellent electrical characteristics. When the content of each of these components is less than 80 parts by weight, the binding force with the surface of the kitchen utensil is reduced and the coating film is peeled off, while the content of each of these components is 100 parts by weight. If it exceeds, the viscosity of the primer coating composition becomes excessively high and the primer coating layer cannot be thin and have a certain thickness.

  N-methyl-2-pyrrolidone used in the undercoat coating composition liquefies polytetrafluoroethylene, polyethersulfone and polyamideimide resin as polar organic solvents, adjusts the viscosity of the undercoat coating composition, and oxidizes. Aluminum, silicon carbide and silica sol provide hardness, impact resistance, abrasion resistance, heat resistance, stain resistance, salt water resistance, corrosion resistance, etc. to the coating film, and serve to reinforce the function of the coating film. .

  The diacetone alcohol used in the undercoat coating composition improves the pigment dispersibility in the composition, smoothes the surface of the coating film during spray coating, and prevents the pinhole phenomenon.

  Examples of inorganic pigments used in the undercoat coating and intermediate coating composition include transition metal oxide inorganic pigments such as titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, iron oxide, cobalt oxide, and chromium oxide, or Examples of the pearl pigment used in the intermediate coating and top coating composition include mica-titanium oxide pearl pigment, but the present invention is not limited thereto. Never happen.

  Examples of water-soluble acrylic resins used in the intermediate coating and top coating compositions include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, normal butyl (meth) acrylate, and isobutyl (meth). Polymers such as acrylate, 2-ethylhexyl (meth) acrylate, hydroxypropyl (meth) acrylate, stearyl (meth) acrylate, and hydroxybutyl (meth) acrylate can be mentioned, but the present invention is limited to this. Absent.

  The water-soluble acrylic resin preferably has a weight average molecular weight of 10,000 to 25,000. However, when the molecular weight is less than 10,000, the processability decreases, and when the molecular weight exceeds 25,000, the stability of the composition decreases. Since the viscosity becomes excessively high, workability is reduced.

  The acrylic dispersant used in the intermediate coating composition is a substance that induces dispersion of a water-soluble acrylic resin in the composition, and is a (meth) acrylic ester non-plastic aqueous polymer dispersant. However, (meth) acrylic ester resins are excellent in adhesiveness, flexibility, alkali resistance, and weather resistance, and are effective not only in the dispersion of water-soluble acrylic resins but also in improving the physical properties of coating films. Is.

  The ethylene glycol monobutyl ether used in the intermediate coating composition is used for the purpose of preventing cracks in the coating film by drying the coating film slowly in a drying path after spray coating.

  The perfluoroalkoxy resin used in the intermediate coating and top coating composition is excellent in thermal stability, excellent in releasability, and provides a function of preventing food from sticking to the coating film. Further, dimethylaminoethanol enhances the storability of the paint and promotes maintaining a constant viscosity, and triethanolamine used in the top coating composition is a catalyst agent that maintains a constant viscosity of the paint. used.

  The dispersant used in the undercoating, intermediate coating, and overcoating composition is preferably a nonionic surfactant, and the nonionic surfactant is not ionic in an aqueous solution. It does not affect other components in the composition and has a uniform dispersion and emulsification performance of solid particles in the composition.

  As such a dispersant, polyoxyethylene nonyl phenyl ether is preferable, and polyoxyethylene nonyl phenyl ether is excellent in solubilization ability, induces uniform dispersion of the composition, Since it has the ability to form a film, it improves physical properties such as corrosion resistance, water resistance, stain resistance, and release properties of the dried coating film.

  Examples of the base material of the kitchen appliance to which the coating method of the present invention can be applied include aluminum, an aluminum alloy, steel, stainless steel, ceramic, and the like, and the type of the material is not limited.

  Hereinafter, the present invention will be described in more detail based on the following examples and test examples.

  However, the following examples are only for illustrating the present invention, and the present invention is not limited by the following examples, and may be substituted within the scope of the technical idea of the present invention. It will be apparent to those skilled in the art to which the present invention pertains that other equivalent embodiments are possible.

  <Example 1> Production of undercoat coating composition

  In order to show excellent adhesion to the surface of the kitchen appliance, the primer coating is carried out. The method for producing the primer coating composition starts with 909 g of a polyamideimide (PAI) paste having a solid content of 25% by weight, 909 g of a polyethersulfone (PES) paste having a content of 20% by weight was mixed, and while stirring at high speed, 136 g of N-methyl-2-pyrrolidone (NMP) solvent, 545 g of pure water, and 68 g of diacetone alcohol (DAA) solvent. Were sequentially mixed and stirred for 20 minutes.

  After sufficiently stirring these, 23 g of black inorganic pigment, 295 g of aluminum oxide powder, 159 g of silicon carbide powder, and 136 g of dispersing agent were added and sufficiently stirred at high speed. When these were completely dispersed, 136 g of a silica sol solution having a content of 30% by weight is charged. Subsequently, 227 g of pure water and 1 kg of polytetrafluoroethylene (PTFE) paste having a solid content of 55% by weight were further added and stirred.

  After the contents are completely mixed and stirred, the viscosity of the primer coating composition can be adjusted by filtering with a 300 mesh filter medium and adding pure water as required (A1-type).

  B1-type to E1-type undercoat coating compositions were produced by the method as described above, and the composition ratios of the respective components are as shown in Table 1 below.

  When the undercoating composition prepared as shown in Table 1 was coated on a kitchen appliance, the composition of A1-type was excellent in adhesion and corrosion resistance with the intermediate coating layer, but B1-type and C1. The composition of -type had good adhesion with the intermediate coating layer, but did not have good corrosion resistance. Also, if the component ratio of polytetrafluoroethylene is changed as in the composition of D1-type and E1-type, the adhesive strength with the intermediate coating layer is poor and a problem occurs in durability. The composition of -type showed the most excellent physical properties.

  <Example 2> Production of intermediate coating composition

  In order to show the three-dimensional pattern texture on the surface of the kitchen utensil, the intermediate coating is carried out. The method for producing the intermediate coating composition starts with 144 g of water-soluble acrylic resin, 154 g of pure water, and 32 g of dimethylaminoethanol (DMAE). While mixing and stirring, 10 g of pearl pigment, 1 kg of polytetrafluoroethylene (PTFE) paste having a solid content of 55% by weight, and 220 g of perfluoroalkoxy (PFA) resin having a solid content of 35% by weight were added.

  After sufficiently stirring these, 100 g of acrylic dispersant, 40 g of dispersant, 60 g of ethylene glycol monobutyl ether (EGBE), and 40 g of black inorganic pigment were added and stirred sufficiently, followed by filtration with a 300-mesh filter medium. After adding 60 g of butylcellulose thickener and stirring until they were thoroughly mixed, the viscosity of the primer coating composition was adjusted by adding 140 g of pure water (A2-type).

  The intermediate coating composition of B2-type to E2-type was produced by the method as described above, and the composition ratio of each component is as shown in Table 2 below.

  When the intermediate coating composition prepared as shown in Table 2 is coated on a sufficiently dried primer coating layer, the composition of B2-type and C2-type has a low viscosity. Formed on a flat surface, the texture of the three-dimensional pattern was weak. In addition, since the compositions of D2-type and E2-type have a very high viscosity, a three-dimensional pattern is well formed on the surface at the time of coating, but cracks of the coating film occur, and wear resistance and corrosion resistance are improved. The problem of falling occurred. In particular, a phenomenon in which the spray gun was blocked by high viscosity occurred.

  In the composition of A2-type, the above-mentioned problems do not occur, it is shown that the adhesive strength between the undercoat coating layer and the topcoat coating layer is the best, and the composition ratio of A-type is most suitable. Turned out.

  <Example 3> Production of top coating composition

  In order to express a three-dimensional pattern texture on the surface of the kitchen utensil and to exhibit excellent releasability, top coating is carried out. First, the method for producing the top coating composition is: 116 g of water-soluble acrylic resin, 254 g of pure water, dimethyl While mixing and stirring 32 g of aminoethanol (DMAE), 1 g of pearl pigment, 1 kg of polytetrafluoroethylene (PTFE) paste with a solid content of 55% by weight, 310 g of perfluoroalkoxy (PFA) resin with a solid content of 35% by weight Was introduced.

  After sufficiently stirring these, 40 g of triethanolamine (TEA), 88 g of a dispersant and 159 g of pure water were added and stirred sufficiently, followed by filtration with a 300-mesh filter material (A3-type).

  The top coating composition of B3-type to E3-type was produced by the method as described above, and the composition ratio of each component is as shown in Table 3 below.

  When the top coating composition prepared as shown in Table 3 was coated on the intermediate coating layer in a wet-on-wet manner, the A3-type composition showed the best adhesion with the intermediate coating layer. The surface releasability was excellent, but the component ratio of perfluoroalkoxy resin was high as in the composition of B3-type and C3-type, or the composition of D3-type and E3-type When the component ratio of the polytetrafluoroethylene resin was increased, the glossiness was decreased, yellowing phenomenon and surface cracks were frequently generated, and the physical properties of the coating film were decreased.

  <Example 4> Surface coating of kitchen appliances

  A low-viscosity A1-type to E1-type undercoating coating composition is coated on a stainless steel frying pan metal substrate at a pressure of 300 kPa using a general spray, dried at 170 ° C. for 20 minutes, dried, and then undercoated The average thickness of the dried coating film of the coating layer was 50 μm.

  After the high-viscosity A2-type to E2-type intermediate coating composition is coated on the dried primer coating layer at a pressure of 150 kPa using a low pressure spray, the intermediate coating composition is dried before being dried. -A top coating composition of A3-type to E3-type having a low viscosity by an on-wet method was coated at a pressure of 300 kPa using a general spray, and then dried at 380 ° C for 25 minutes.

  At this time, the A1-type undercoat coating composition, the A2-type intermediate coat composition, and the A3-type topcoat composition are combined and coated, and the remaining types of compositions are applied in this manner. After the final drying, the average thicknesses of the dry coatings of the intermediate coating layer and the top coating layer were 150 μm and 50 μm, respectively.

  <Test example> Analysis of physical properties of coating film on kitchen appliances

  In Example 4, the physical properties of the kitchen utensil after the coating operation was completed were analyzed, and the results are shown in Table 4 below. The analysis method is as follows.

  -Releasability (non-adhesiveness): The egg white was heated at 200 ° C, and after 30 seconds, it was measured whether or not it naturally separated, and this was repeated 50 times for experiments.

  -Pencil hardness: Using a pencil hardness tester, 10 cm was drawn with a force of 1 kg / f and a speed of 1 m / sec, and this was repeated 10 times.

  -Adhesiveness: After making 100 grids at an interval of 1 mm, and sticking this with cellophane tape, the number of peels was calculated.

  -Impact resistance: A 500 g steel ball was dropped from a height of 30 cm, and the presence or absence of peeling of the coating film was confirmed.

  -Water resistance: It was immersed in tap water, and after 200 hours, the presence or absence of swelling and peeling was confirmed.

  -Humidity resistance: After standing at a temperature of 80 ° C and a relative humidity of 95% for 72 hours, the presence or absence of swelling and peeling was confirmed.

  -Abrasion resistance: GS-17 made of wheel material is rotated 15000 times at a load of 3 kg and a speed of 60 rpm using a Taber abrasion tester, and then the presence or absence of damage to the coating film is confirmed. did.

  -Contamination resistance: The surface of the coating film was coated with a sexual pen and placed at 20 ° C for 24 hours, and then wiped with a solvent to confirm the presence or absence of stains.

  -Salt water resistance: After putting in 10% salt water and boiling at 100 ° C for 36 hours, the presence or absence of erosion of the coating film was confirmed.

  -Acid resistance: It was immersed in a 98% acetic acid solution, and after 24 hours, the presence or absence of swelling, peeling, cracking, or discoloration of the coating film was confirmed.

  -Alkali resistance: It was immersed in a 5% sodium carbonate solution, and after 24 hours, the presence or absence of swelling, peeling, cracking, or discoloration of the coating film was confirmed.

  -Accelerated weather resistance: After 2000 hours test using a sunshine weather meter, the presence or absence of discoloration of the coating film was confirmed.

  Looking at the results of Table 4 above, the items of non-adhesiveness, pencil hardness, adhesion, impact resistance, abrasion resistance, and contamination resistance did not show any difference for each group, but water resistance and moisture resistance. In this experiment, the content of polyamideimide and polyethersulfone in the undercoating coating composition deviated from the scope of the present invention, and peeling was observed in B-type and C-type having a low content of thickener in the intermediate coating composition. A phenomenon was observed. From these results, the viscosity is appropriately determined only when the polyamideimide and polyethersulfone components of the undercoat coating composition and the thickener component in the intermediate coating composition are mixed in an appropriate range in the composition. It can be seen that the surface of the kitchen utensil and the undercoat coating layer, the undercoat coating layer and the intermediate coating layer are firmly bonded to each other, and moisture permeation is prevented.

  In the salt water resistance experiment, erosion occurred in D-type and E-type with a high content of thickener in the intermediate coating composition and a low content of perfluoroalkoxy resin in the top coating composition. Is mainly attributed to the fact that the content of the perfluoroalkoxy resin excellent in thermal stability in the top coating composition does not reach an appropriate level.

  In the acid resistance and alkali resistance experiments, C-type, D-type and E-type, and in the accelerated weather resistance experiment, defects occurred in B-type to E-type, but the water resistance, moisture resistance, As in the salt water resistance experiment, it can be seen that the interlaminar binding force due to the viscosity of the composition, thermal stability, and the like affect the chemical properties of the coating film and the resistance to changes in the external environment.

  To summarize the above results, the main factors affecting many physical properties required for kitchen appliances are not only the intrinsic properties of each component constituting the coating composition, but also the difference in viscosity depending on the type and content of these components. It is analyzed to determine the properties of the coating film by affecting the morphology of each layer and the binding force between each layer.

DESCRIPTION OF SYMBOLS 1 ... Base material layer of a kitchen appliance, 2 ... Undercoat coating layer, 3 ... Intermediate coating layer, 4 ... Topcoat coating layer.

Claims (7)

100 parts by weight of polytetrafluoroethylene paste (solid content 50% to 60% by weight), 10 parts by weight to 20 parts by weight of N-methyl-2-pyrrolidone, 70 parts by weight to 85 parts by weight of water, 10% by weight of dispersant Parts to 20 parts by weight, polyethersulfone paste (solids content 13% to 30% by weight) 80 parts to 100 parts by weight, polyamideimide paste (solids content 13% to 30% by weight) 80 parts to 100% Parts by weight, 1 part by weight to 5 parts by weight of inorganic pigment, 25 parts by weight to 35 parts by weight of aluminum oxide, 10 parts by weight to 20 parts by weight of silicon carbide, 10 parts by weight of silica sol (solid content 25% to 35% by weight) Preparing a primer coating composition by mixing 20 parts by weight and 5 parts by weight to 10 parts by weight of diacetone alcohol;
Coating the surface of the kitchen appliance with the primer coating composition at a pressure of 100 kPa to 500 kPa, and drying at 50 ° C. to 280 ° C. for 5 minutes to 30 minutes to form a primer coating layer;
100 parts by weight of polytetrafluoroethylene paste (solid content: 50% to 60% by weight), 10 parts by weight to 20 parts by weight of water-soluble acrylic resin, 25 parts by weight to 35 parts by weight of water, 1 part by weight of dimethylaminoethanol 5 parts by weight, pearl pigment 0.5 parts by weight to 5.0 parts by weight, perfluoroalkoxy resin (solid content 20% by weight to 50% by weight) 20 parts by weight to 30 parts by weight, acrylic dispersant 5 parts by weight to 15 parts by weight By mixing parts by weight, 2 to 6 parts by weight of dispersant, 4 to 7 parts by weight of thickener, 4 to 8 parts by weight of ethylene glycol monobutyl ether, and 2 to 5 parts by weight of inorganic pigment. Providing an intermediate coating composition;
Forming the intermediate coating layer by coating the intermediate coating composition on the dried primer coating layer at a pressure of 10 kPa to 300 kPa;
100 parts by weight of polytetrafluoroethylene paste (solid content: 50% to 60% by weight), 7 to 13 parts by weight of water-soluble acrylic resin, 30 to 50 parts by weight of water, 1 part by weight of dimethylaminoethanol 5 parts by weight, 0.05 parts by weight to 0.5 parts by weight of pearl pigment, 25 parts by weight to 35 parts by weight of perfluoroalkoxy resin (solid content 20% to 50% by weight), 2 parts by weight to 6 parts of triethanolamine Preparing a top coating composition by mixing 5 parts by weight and 5 parts by weight to 10 parts by weight of a dispersant; and wet-on-coating the top coating composition on the intermediate coating layer at a pressure of 100 kPa to 500 kPa. Coat by wet method, and top coat by drying at 350 to 450 ° C for 5 to 50 minutes A method of surface coating showing a three-dimensional pattern texture comprising: forming a layer.   3. The three-dimensional pattern texture according to claim 1, wherein the coating thickness of the undercoating layer and the top coating layer is 10 μm to 100 μm, and the coating thickness of the intermediate coating layer is 30 μm to 300 μm. Showing surface coating method.   The primer coating layer is formed on the surface of the kitchen appliance with a constant and thin thickness, the intermediate coating layer is formed with an irregular and thick thickness on the primer coating layer, and the top coating layer is formed on the intermediate coating layer. 3. The surface coating method showing a three-dimensional pattern texture according to claim 2, wherein the irregular surface shape of the intermediate coating layer is shown as it is while being formed with a constant and thin thickness.   The viscosity of the undercoat coating composition and the topcoat coating composition is Zahn cup # 3 viscosity of 8 seconds to 15 seconds, and the viscosity of the intermediate coating composition is 50,000 cP to 100,000 cP. Surface coating method showing three-dimensional pattern texture. The inorganic pigment of the undercoat coating composition and the intermediate coating composition is titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, iron oxide, cobalt oxide, chromium oxide, graphite, carbon nanotube or carbon black,
2. The surface coating method according to claim 1, wherein the pearl pigment of the intermediate coating composition and the top coating composition is a mica-titanium oxide pearl pigment.   The surface coating method according to claim 1, wherein the acrylic dispersant is a (meth) acrylic ester dispersant. 2. The surface coating method according to claim 1, wherein the water-soluble acrylic resin of the intermediate coating composition and the top coating composition has a weight average molecular weight of 10,000 to 25,000.