Coating composition with high durability and releasability for stainless steel, and manufacturing method thereof

Abstract

The present invention relates to a coating composition with high durability and releasability for stainless steel, and a manufacturing method thereof. The coating composition for stainless steel, according to the present invention, comprises a topcoat composition applied on top of an undercoat composition, wherein: the undercoat composition includes porous ceramic particles having a plurality of pores formed in the surfaces thereof and an auxiliary composition for releasability contained in the plurality of pores; and the topcoat composition may comprise 15-30 wt% of polydimethylsiloxane (PDMS), 0.05-0.2 wt% of hydrochloric acid, 4-10 wt% of distilled water, and 15-25 wt% of silica colloid.

Description

Coating composition for stainless steel having high durability and release properties and method for manufacturing the same

[0001] The present invention relates to a coating composition for stainless steel used for coating kitchen utensils, etc., and to a coating composition for stainless steel having high durability and release properties, and a method for manufacturing the same.

[0002] Release agents are used to facilitate the release and detachment of specific substances from a surface; however, surface coating agents with permanent release properties may experience separation and / or wear of the release-prone surface coating layer from the substrate due to repeated use, or their lifespan may be reduced due to continuous heating and / or cooling cycles.

[0003] Another type of release agent is silicone, which can be utilized in the form of: 2) the application of a thin silicone sheet (including optionally enclosed reinforcing structures) placed flat on a cooking surface; 3) a thin coating of silicone sprayed (typically resins) and / or coated on trays or pans (Bundy Pans); and 4) trays or pans molded from silicone (typically elastomeric silicone).

[0004] Although a thicker silicone coating may be used to increase the lifespan of the silicone coating, the silicone limits heat transfer from the heat source to the heat source on the surface, and thus may cause problems in heating the food to an appropriate temperature or increasing the time required to heat the food.

[0005] Surfaces coated with a thin thickness using methods such as spray coating have a short service life due to the tendency of the silicone to separate from the substrate and / or wear away.

[0006] Generally, to facilitate heat transfer, the silicon coating is designed to maintain close surface-to-surface contact between the substrate and the silicon; however, due to the different coefficients of thermal expansion of the silicon and the substrate containing the silicon coating, the silicon is eventually released from the substrate surface after several baking cycles.

[0007] U.S. Patent Publication No. 2006 / 0102013 discloses a coating technology applied to the surface of cooking utensils, etc.

[0008] Meanwhile, as concerns regarding the harmfulness of fluoropolymer coatings to the human body are constantly being raised, there is a need to develop a coating composition with improved service life and superior release properties and thermal conductivity as a silicone coating technology capable of resolving these issues.

[0009] The present invention aims to provide a coating composition for stainless steel having high heat resistance and release properties when coated on a substrate such as stainless steel.

[0010] The present invention aims to provide a coating composition for stainless steel that has improved service life and is harmless to the human body.

[0011] The present invention also aims to provide a stainless steel coating composition having characteristics suitable for application to kitchenware, etc.

[0012] A coating composition for stainless steel having high durability and release properties according to the present invention, for solving the above-mentioned problem, comprises a primer composition coated on the surface of an adhesive and a topcoat composition coated on top of the primer composition, wherein the primer composition comprises porous ceramic particles having a plurality of pores formed on their surface and a release-promoting auxiliary composition supported in the plurality of pores, and the topcoat composition comprises 35 to 55 weight% of polydimethylsiloxane (PDMS), 0.05 to 0.2 weight% of hydrochloric acid, 4 to 10 weight% of distilled water, and 30 to 45 weight% of silica colloid.

[0013] In the present invention, the release agent auxiliary composition comprises 10 to 20 parts by weight of hydroxy silicone oil, 5 to 10 parts by weight of polydimethylsiloxane, 1 to 3 parts by weight of octamethylcyclotetrasiloxane, and 0.1 to 1 part by weight of castor oil, based on 100 parts by weight of the porous ceramic particles.

[0014] In the present invention, the porous ceramic particles may be characterized by having a pore diameter of 10 to 1000 nm (nanometer) and having a metal coating on the inner surface of the pores.

[0015] In the present invention, the stainless steel coating composition may maintain release properties at a temperature of 250 °C or higher.

[0016] The present invention also provides a method for preparing a coating composition for stainless steel, comprising a) a step of preparing a primer composition and b) a step of preparing a topcoat composition, wherein the step of preparing the primer composition is a step of mixing and stirring a porous ceramic particle having a plurality of pores formed on its surface and a release agent composition supported in the plurality of pores, and a polydimethylsiloxane with distilled water containing hydrochloric acid or nitric acid, and the step of preparing the topcoat composition is a step of dispersing a silica colloid in ethyl acetate and then uniformly mixing polydimethylsiloxane, hydrochloric acid, and distilled water.

[0017] The coating composition for stainless steel according to the present invention is coated onto a substrate composed of stainless steel or the like, and has high heat resistance and release properties.

[0018] The stainless steel coating composition according to the present invention has an improved service life and possesses characteristics that are harmless to the human body.

[0019] The stainless steel coating composition according to the present invention has characteristics suitable for application to kitchenware, etc.

[0020] Hereinafter, each component of the present invention is described in more detail so that a person skilled in the art to which the present invention pertains can easily implement it; however, this is merely an example, and the scope of the rights of the present invention is not limited by the following.

[0021] As used in this invention, "preferably" or "preferably" refers to an embodiment of the invention having a specific advantage under specific conditions. However, other embodiments may also be preferred under the same or different conditions. Furthermore, one or more preferred embodiments do not imply that other embodiments are not useful, nor do they exclude other embodiments within the scope of the invention.

[0022] The term “comprising” as used herein is used when listing materials, compositions, devices, and methods useful for the present invention, and is not limited to the examples listed.

[0023] In particular, the term "comprising" in the present invention refers to various states, such as a state in which the component is included as is, a state in which the component is processed using a precursor material, or a state in which the component is satisfied after processing, and is not limited to the examples listed.

[0024] The coating composition for stainless steel according to the present invention is used for kitchenware that is exposed to high heat and requires release properties, such as frying pans, oven trays, and oven molds, for a long time at high temperatures. It maintains release properties even after exposure to high temperatures, so that food does not stick to the kitchenware and can be easily separated.

[0025] In particular, the purpose is to present a stainless steel coating composition that does not affect the health of users by using a material with almost no human health hazards, such as silicone, instead of using existing materials that raise concerns regarding human health hazards, such as perfluorinated compounds.

[0026] Specifically, existing silicone-based ceramic coating agents use silicone oil that evaporates from about 280°C to achieve release properties, and thus when coated on kitchen utensils (such as frying pans), the oil evaporates when the temperature of the pan exceeds 280°C, resulting in a permanent loss of release properties. The present invention relates to a ceramic coating agent that allows the oil to maintain release properties without evaporating even at temperatures above 330°C.

[0027] More specifically, the composition comprises a primer composition coated on the surface of an adhesive and a topcoat composition coated on top of the primer composition, wherein the primer composition comprises porous ceramic particles having a plurality of pores formed on their surface and a release agent composition supported in the plurality of pores, and the topcoat composition comprises 35 to 55 weight% of polydimethylsiloxane (PDMS), 0.05 to 0.2 weight% of hydrochloric acid, 4 to 10 weight% of distilled water, and 30 to 45 weight% of silica colloid.

[0028] The above polydimethylsiloxane is a binder, and if it is added in an excess amount compared to the above content, the content of other components decreases, and in particular, the content of silica colloid decreases, which may result in a problem where the release properties on the surface of the topcoat coating layer coated with a topcoat composition that comes into direct contact with food, etc., are actually reduced. If it is added in a small amount compared to the above content, the effect of the silicone oil component supplied from the undercoat layer being delivered and maintained in the topcoat coating layer by the silica particles decreases, resulting in a problem where the release properties are maintained and the surface hardness decreases.

[0029] If the above hydrochloric acid content is lower than the above content, the degree of polymerization of GPTMS is low and the reaction cannot proceed sufficiently, and if it is higher than the above content, the reaction rate is too fast and it becomes difficult to achieve a homogeneous reaction, resulting in a problem where the coating layer cannot be formed uniformly.

[0030] In addition, if the content of the silica colloid is less than the above content, there is a problem with reduced heat resistance, and if it is excessive, there may be a problem with reduced transparency of the coating film or reduced durability of the top coating layer.

[0031] Meanwhile, the above primer composition comprises porous ceramic particles having a plurality of pores formed on their surface and a release agent auxiliary composition supported in the plurality of pores. At this time, the primer composition may further include a binder.

[0032] The above release agent auxiliary composition may comprise 10 to 20 parts by weight of hydroxy silicone oil, 5 to 10 parts by weight of polydimethylsiloxane, 1 to 3 parts by weight of octamethylcyclotetrasiloxane, and 0.1 to 1 part by weight of castor oil, based on 100 parts by weight of the porous ceramic particles.

[0033] The above-mentioned release agent composition includes hydroxy silicone oil and octamethylcyclotetrasiloxane, and also includes a binder such as polydimethylsiloxane to prevent the silicone oil from being easily released or lost within the pores, thereby serving to continuously supply silicone oil components to the topcoat layer.

[0034] By providing these silicone oil components continuously and at low concentrations, it plays a role in maintaining excellent release properties of the topcoat layer.

[0035] Generally, even at temperatures above 250°C where silicone oil typically evaporates, the silicone oil is not lost and is continuously supplied from the undercoat layer to the topcoat layer, thereby providing the effect of maintaining release properties for a long period. More preferably, it is maintained even at temperatures above 300°C, and most preferably, it is maintained even at temperatures above 330°C for a long period.

[0036] If the content of the above hydroxy silicone oil is excessive, there is a problem that the release life is reduced and the surface hardness is lowered, and even if it is added in a small amount less than the above content, there is a problem that the release of the top coating layer is not maintained for a long period of time.

[0037] Meanwhile, the addition of the above castor oil is intended to improve the miscibility between the components, but if it is added in excess of the above amount, there is a problem in that the composition is not supported within the pores of the porous particles due to the residual castor oil, and the remaining amount of the composition remains.

[0038] The porous ceramic particles may have a pore diameter of 10 to 1000 nm (nanometers) and a metal coating on the inner surface of the pores.

[0039] Preferably, the diameter may be 100 to 150 nm, and the metal coated inside the pore is preferably copper. By coating the inside of the pore with copper metal, the composition is not easily lost to the outside of the pore due to the interaction between the coating surface and the release agent composition, and the release agent composition is gradually released according to the external composition.

[0040] After immersing porous ceramic particles in an aqueous solution in which copper ions are dispersed, the mixture is thoroughly mixed, and then a reducing agent is added in an amount greater than an equivalent to reduce the metal. Subsequently, the outer surface of the particles is washed 5 to 8 times, thereby removing most of the coating layer formed on the surface through washing, so that the coating layer is retained inside the pores.

[0041] The porous ceramic particles may be included in an amount of 30 to 45 weight% based on the total weight of the primer composition, and may also include 35 to 55 weight% of polydimethylsiloxane, 0.2 to 0.5 weight% of hydrochloric acid, and 5 to 12 weight% of distilled water.

[0042] If the content of polydimethylsiloxane is added in a small amount less than the above amount, the surface hardness of the coating film is reduced, and if it is added in an excessive amount more than the above amount, the adhesion to the top coating layer formed on the undercoat layer is reduced, and interlayer separation may occur.

[0043] If the hydrochloric acid content is excessive, the degree of polymerization of polydimethylsiloxane decreases, making it difficult to form a coating layer with sufficient strength and uniform thickness. Furthermore, the excessive time required to form the coating layer results in poor workability. In particular, since the primer composition requires an additional process step of applying the topcoat composition, the composition can be configured to include a higher amount of hydrochloric acid compared to the topcoat composition described later to improve workability, thereby ensuring rapid drying and workability.

[0044] Meanwhile, the above-mentioned topcoat composition comprises 35-55% by weight of polydimethylsiloxane, 0.05-0.2% by weight of hydrochloric acid, 4-10% by weight of distilled water, and 30-45% by weight of silica colloid.

[0045] When the content of polydimethylsiloxane is added in a small amount greater than the above amount, the surface hardness of the coating film is reduced, and when it is added in an excessive amount greater than the above amount, it is difficult to form a uniform coating layer, or even though the silicone oil component is supplied at a certain concentration in the undercoat layer to maintain release properties, the penetration rate of the silicone oil into the topcoat layer is low, resulting in a problem of reduced release properties.

[0046] When the hydrochloric acid content is excessive, the degree of polymerization of polydimethylsiloxane is reduced, making it difficult to form a coating layer with sufficient strength and uniform thickness, and the excessive time required to form the coating layer results in poor workability. This is intended to ensure that, unlike the aforementioned primer composition, the coating layer is formed as a layer exposed on the outer surface, and by controlling the curing speed of the coating layer so that it can be formed as a uniform and smooth surface, a layer with uniform surface hardness is formed on the surface.

[0047] If the above silica colloid content is added in excess, there is a problem that it is difficult to form a uniform coating layer, and if it is added in a small amount less than the above content, there is a problem that heat resistance and wear resistance are reduced.

[0048] Meanwhile, the above-mentioned topcoat composition may further include other components, such as dispersants and additives, as needed.

[0049] For example, based on 100 parts by weight of the topcoat composition, 10 to 30 parts by weight of a dispersant prepared by dispersing polydimethylsiloxane powder (350 mesh) in a solvent mixed with distilled water and ethyl acetate in a weight ratio of 4:1 as a dispersant may be added, or 1 to 5 parts by weight of polysiloxaneimide, which is an additive for improving hardness and adhesion strength, may be further included.

[0050] However, if added in excess of the above amount, the coating performance may be reduced or it may be unsuitable for performing coating processes such as dip coating due to an increase in solids.

[0051] The present invention also provides a method for manufacturing the above-described coating composition for stainless steel.

[0052] Specifically, the present invention provides a method for preparing a coating composition for stainless steel, comprising a) a step of preparing a primer composition and b) a step of preparing a topcoat composition, wherein the step of preparing the primer composition comprises mixing and stirring porous ceramic particles having a plurality of pores formed on their surface and a release agent composition supported in the plurality of pores, polydimethylsiloxane, and distilled water containing hydrochloric acid, and the step of preparing the topcoat composition comprises uniformly mixing silica colloid, polydimethylsiloxane, hydrochloric acid, and distilled water.

[0053] More specifically, the step of preparing the above undercoat composition may first be performed by degreasing and washing porous ceramic particles, adding an aqueous metal ion solution and mixing at a speed of 20 rpm for 40 to 60 minutes, and then adding a reducing agent such as ascorbic acid and mixing at a speed of 20 rpm for 20 to 40 minutes to form a reactive metal coating layer.

[0054] Next, after forming the metal coating layer, the porous ceramic particles are washed with purified water 5 to 8 times to remove surface residue, and the particles are dried in a vacuum dryer to a moisture content of 10% or less to prepare them.

[0055] Based on 100 parts by weight of the above powder (particles), a mixed composition is prepared by stirring 15 parts by weight of hydroxy silicone oil, 6 parts by weight of polydimethylsiloxane, 3 parts by weight of octamethylcyclotetrasiloxane, and 0.2 parts by weight of castor oil for 5 hours, then the previously washed powder is mixed and stirred for 3 hours, and then maintained for 24 hours to produce porous ceramic particles supported with a release agent composition, and then a primer composition is prepared by mixing and stirring with polydimethylsiloxane and distilled water containing hydrochloric acid.

[0056] The step of preparing the above-mentioned topcoat composition first involves mixing silica colloid, polydimethylsiloxane, hydrochloric acid, and distilled water, and stirring for 100 to 140 minutes while refluxing at 75 to 120°C.

[0057] If the reflux temperature is lower than the above temperature, the two-dimensional polymerization reaction takes too much time, and if it is higher than the above temperature, the hydrolysis reaction is not smooth and the vapor pressure is high, so there is a risk of explosion during production.

[0058] If stirring is performed for a shorter time than the above time, the polymerization reaction does not occur sufficiently, and if it is performed for an excessive time, the stirring time after the polymerization is completed becomes meaningless; therefore, in terms of manufacturing efficiency, it is desirable to perform the process within the above time range.

Claims

1. A coating composition for stainless steel having high durability and release properties, A primer composition coated on the surface of an adhesive and It includes a topcoat composition coated on the upper surface coated with the above undercoat composition, and The above undercoat composition comprises porous ceramic particles having a plurality of pores formed on their surface and a release agent auxiliary composition supported in the plurality of pores, and The above porous ceramic particles have a pore diameter of 10 to 1,000 nm (nanometers), and The inner surface of the above pore is coated with metal, and The above topcoat composition is a coating composition for stainless steel comprising 15 to 30 weight% of polydimethylsiloxane (PDMS), 0.05 to 0.2 weight% of hydrochloric acid, 4 to 10 weight% of distilled water, and 15 to 25 weight% of silica colloid.

2. In Paragraph 1, The above release agent auxiliary composition is a coating composition for stainless steel comprising 10 to 20 parts by weight of hydroxy silicone oil, 5 to 10 parts by weight of polydimethylsiloxane, 1 to 3 parts by weight of octamethylcyclotetrasiloxane, and 0.1 to 1 part by weight of castor oil, based on 100 parts by weight of the porous ceramic particles.

3. A method for manufacturing a coating composition for stainless steel according to claim 1, a) A step of manufacturing a primer composition and b) Step of manufacturing the topcoat composition Includes, The step of preparing the above-mentioned primer composition is a step of mixing and stirring distilled water containing hydrochloric acid or nitric acid with porous ceramic particles having a plurality of pores formed on the surface and a release agent auxiliary composition supported in the plurality of pores, and polydimethylsiloxane (PDMS). The step of preparing the above-mentioned topcoat composition is to disperse silica colloid in ethyl acetate, and then uniformly mix polydimethylsiloxane, hydrochloric acid, and distilled water. Method for manufacturing a coating composition for stainless steel.