Polymer precoated cold rolled enamel steel sheet and method of manufacturing the same

Abstract

The present application relates to a kind of polymer precoating cold-rolled enamel steel plate and its manufacturing method, and the polymer precoating of cold-rolled enamel steel plate surface is made of the following weight percentage of raw materials: polymer 20%~30%, surfactant 5%~10%, corrosion inhibitor 3%~6%, and the rest is water.By coating polymer coating on the surface of cold-rolled enamel steel plate, the corrosion resistance of the steel plate before enamelling is improved, the reaction activity between enamel and steel plate is improved, the adhesion of enamel layer is improved, and the cold-rolled enamel steel plate can be treated without oil coating, the pre-coating lubricating oil, degreasing, pickling, batch nickel and other pretreatment steps in use process are saved, and the green environmental protection effect of cold-rolled enamel steel surface pretreatment is achieved.

Description

Technical Field

[0001] This invention relates to the field of cold rolling production technology, and in particular to a polymer pre-coated cold-rolled enamel steel sheet and its manufacturing method. Background Technology

[0002] Enameled steel products are composite materials that combine the strength and formability of steel plates with the corrosion resistance, wear resistance, and bright colors of inorganic glassy enamel materials. They are widely used in various fields such as light industry, home appliances, and construction.

[0003] In recent years, with increasingly stringent environmental protection requirements (such as the EU's REACH regulations), end products with a nickel content exceeding 0.1% are required to be labeled with a "carcinogenic risk" label. Against this backdrop, how to achieve green and environmentally friendly pretreatment of enamel steel surfaces has received increasing attention. The method of coating the surface of cold-rolled enamel steel with a polymer coating has advantages such as providing temporary corrosion protection for the steel plate, reducing the surface friction coefficient of the steel plate, and improving the reactivity between the enamel and the steel plate. At the same time, it can eliminate the need for the steel mill to apply anti-rust oil, and can save multiple pretreatment steps such as pre-coating lubricating oil, degreasing, pickling, and nickel plating during the processing and production process.

[0004] Currently, there are relatively few cold-rolled enamel steel products with polymer pre-coating. Similar products include:

[0005] Chinese invention patent CN 101896644 B discloses a "method for producing enamel steel materials or parts," wherein the steel sheet or parts are coated with a coating consisting of a polymer matrix in which non-oxide ceramic particles are uniformly dispersed. It also relates to the use of such coated steel sheets or parts in the production of enamel steel sheets or parts, and a method for producing enamel steel sheets or parts that allows for lower firing temperatures and times than conventional firing times and temperatures.

[0006] Chinese invention patent CN 101952483 B discloses a "method for manufacturing enamel steel substrate", which includes the following steps: providing a steel substrate; applying a solution containing a solvent, a polymer precursor and at least one metal or metal oxide to the surface of the steel substrate, wherein the metal or metal oxide is suitable for promoting the adhesion of a enamel layer to the surface of the steel substrate; curing the steel substrate, thereby removing the solvent and forming an organic layer containing the at least one metal or metal oxide; applying a enamel layer to the organic layer; and then performing a firing step to obtain the enamel steel substrate.

[0007] The polymers used to coat the surface of the above-mentioned types of cold-rolled enamel steel products all require the addition of other additives, such as non-oxide ceramic particles or a solution of a metal or metal oxide. This increases the production cost of polymer cold-rolled enamel steel products, and the complex polymer formulations are also not conducive to the application during production and the control of the final product performance. Summary of the Invention

[0008] This invention provides a polymer-pre-coated cold-rolled enamel steel sheet and its manufacturing method. By coating the surface of the cold-rolled enamel steel sheet with a polymer coating, the corrosion resistance of the steel sheet before enamel coating is improved, the reactivity between the enamel and the steel sheet is improved, and the adhesion of the enamel layer is improved. At the same time, it can realize the oil-free treatment of cold-rolled enamel steel sheet, eliminating the pre-treatment steps such as pre-coating with lubricating oil, degreasing, pickling, and nickel plating during use, thus achieving the green and environmentally friendly effect of surface pretreatment of cold-rolled enamel steel.

[0009] To achieve the above objectives, the present invention employs the following technical solution:

[0010] A polymer pre-coated cold-rolled enamel steel sheet, wherein the polymer pre-coating on the surface of the cold-rolled enamel steel sheet is composed of the following raw materials by weight percentage: 20% to 30% polymer, 5% to 10% surfactant, 3% to 6% corrosion inhibitor, and the remainder being water.

[0011] Furthermore, the cold-rolled enamel steel sheet is an ultra-low carbon titanium-containing cold-rolled enamel steel sheet or an extremely low carbon high-oxygen cold-rolled enamel steel sheet.

[0012] Furthermore, the polymer is one or both of waterborne acrylic resin and waterborne polyurethane resin.

[0013] Furthermore, the surfactant is a nonionic surfactant.

[0014] Furthermore, the nonionic surfactant is one or both of polypropylene glycol and alkyl glucoside.

[0015] Furthermore, the corrosion inhibitor is one or more of chromates, silicates, and nitrites.

[0016] A method for manufacturing a polymer-pre-coated cold-rolled enamel steel sheet includes: mixing a polymer, a surfactant, and a corrosion inhibitor in weight percentages, adding the mixture to a container filled with water and stirring to obtain a polymer preparation; then coating the polymer preparation onto the surface of the cold-rolled enamel steel sheet by roller coating or dipping; and finally curing the polymer preparation onto the surface of the cold-rolled enamel steel sheet.

[0017] Furthermore, the curing process employs hot air curing, with a curing temperature of 100–130°C and a curing time of 90–150 seconds.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] By coating the surface of cold-rolled enamel steel sheets with a polymer coating, the corrosion resistance of the steel sheet before enamel coating is improved, the reactivity between the enamel and the steel sheet is enhanced, and the adhesion of the enamel layer is improved. At the same time, it can achieve oil-free treatment of cold-rolled enamel steel sheets, eliminating the need for pre-treatment steps such as pre-coating with lubricating oil, degreasing, pickling, and nickel plating during use, thus achieving a green and environmentally friendly effect of surface pretreatment of cold-rolled enamel steel. Detailed Implementation

[0020] The present invention discloses a polymer pre-coated cold-rolled enamel steel sheet. The polymer pre-coating on the surface of the cold-rolled enamel steel sheet is composed of the following raw materials by weight percentage: 20% to 30% polymer, 5% to 10% surfactant, 3% to 6% corrosion inhibitor, and the remainder is water.

[0021] Furthermore, the cold-rolled enamel steel sheet is an ultra-low carbon titanium-containing cold-rolled enamel steel sheet or an extremely low carbon high-oxygen cold-rolled enamel steel sheet.

[0022] Furthermore, the polymer is one or both of waterborne acrylic resin and waterborne polyurethane resin.

[0023] Furthermore, the surfactant is a nonionic surfactant.

[0024] Furthermore, the nonionic surfactant is one or both of polypropylene glycol and alkyl glucoside.

[0025] Furthermore, the corrosion inhibitor is one or more of chromates, silicates, and nitrites.

[0026] A method for manufacturing a polymer-pre-coated cold-rolled enamel steel sheet includes: mixing a polymer, a surfactant, and a corrosion inhibitor in weight percentages, adding the mixture to a container filled with water and stirring to obtain a polymer preparation; then coating the polymer preparation onto the surface of the cold-rolled enamel steel sheet by roller coating or dipping; and finally curing the polymer preparation onto the surface of the cold-rolled enamel steel sheet.

[0027] Furthermore, the curing process employs hot air curing, with a curing temperature of 100–130°C and a curing time of 90–150 seconds.

[0028] The main functions of the polymers selected in this invention, namely waterborne acrylic resins and / or waterborne polyurethane resins, are: firstly, to provide protection for the base steel plate, preventing corrosion of the substrate by moisture, oxygen, and other chemicals; secondly, to use the polymer as an intermediate carrier, as it can contact both the enamel powder and the steel plate separately. During high-temperature enameling, the polymer pyrolysis products promote the reaction between the molten enamel and the alloying elements on the steel plate surface, forming a two-phase anchoring structure with uneven surfaces, thereby improving the adhesion performance of the enamel product. The polymer addition ratio is controlled at 20% to 30%, which not only protects the substrate and improves adhesion performance, but also allows it to fully pyrolyze during the enameling process, avoiding defects such as pinholes and enamel layer detachment caused by residues when added in excess.

[0029] The nonionic surfactants used in this invention are polypropylene glycol and / or alkyl glucoside, mainly to exert their wetting effect, which can improve the wetting effect of the polymer liquid on the solid surface of the steel plate, making it easier to spread on the surface of the steel plate and form a uniform polymer coating after curing.

[0030] The corrosion inhibitor described in this invention is selected from one or more of chromates, silicates and nitrites. It is mainly water-based acrylic resin and water-based polyurethane resin, which are both weakly acidic (pH value of 5 to 7). By adding a certain amount of corrosion inhibitor, corrosion protection can be provided for steel plates.

[0031] To more intuitively illustrate the present invention, the embodiments of the present invention will be further described in conjunction with the examples. The following examples are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention, including simple variations or equivalent substitutions, are all within the scope of protection of the present invention.

[0032]

Example 1

[0033] In this embodiment, the polymer pre-coating on the surface of the cold-rolled enamel steel sheet is composed of the following raw materials by weight percentage:

[0034]

[0035] The water-based acrylic resin, alkyl glucoside, sodium chromate, sodium nitrite and water are mixed in a container according to the above weight percentages. After stirring evenly, the mixture is roller coated onto the surface of a cold-rolled enamel steel sheet and cured with hot air at a curing temperature of 100°C for 150 seconds to obtain a polymer pre-coated cold-rolled enamel steel sheet.

[0036]

Example 2

[0037] In this embodiment, the polymer pre-coating on the surface of the cold-rolled enamel steel sheet is composed of the following raw materials by weight percentage:

[0038]

[0039] The waterborne polyurethane resin, polypropylene glycol, alkyl glucoside, sodium silicate, sodium nitrite and water are mixed in a container according to the above weight percentages. After stirring evenly, the mixture is roller coated onto the surface of cold-rolled enamel steel sheet and cured with hot air at a curing temperature of 110°C for 100 seconds to obtain a polymer pre-coated cold-rolled enamel steel sheet.

[0040]

Example 3

[0041] In this embodiment, the polymer pre-coating on the surface of the cold-rolled enamel steel sheet is composed of the following raw materials by weight percentage:

[0042]

[0043] The waterborne polyurethane resin, polypropylene glycol, alkyl glucoside, sodium chromate and water are mixed in a container according to the above weight percentages. After stirring evenly, the mixture is roller coated onto the surface of a cold-rolled enamel steel sheet and cured with hot air at a curing temperature of 130°C for 90 seconds to obtain a polymer pre-coated cold-rolled enamel steel sheet.

[0044]

Example 4

[0045] In this embodiment, the polymer pre-coating on the surface of the cold-rolled enamel steel sheet is composed of the following raw materials by weight percentage:

[0046]

[0047] The waterborne polyurethane resin, polypropylene glycol, alkyl glucoside, sodium chromate and water are mixed in a container according to the above weight percentages. After stirring evenly, the mixture is roller coated onto the surface of a cold-rolled enamel steel sheet and cured with hot air at a curing temperature of 120°C for 130 seconds to obtain a polymer pre-coated cold-rolled enamel steel sheet.

[0048]

Example 5

[0049] In this embodiment, the polymer pre-coating on the surface of the cold-rolled enamel steel sheet is composed of the following raw materials by weight percentage:

[0050]

[0051] The waterborne acrylic resin, waterborne polyurethane resin, alkyl glucoside, sodium chromate, sodium silicate, sodium nitrite and water are mixed in a container according to the above weight percentages. After stirring evenly, the mixture is roller coated onto the surface of cold-rolled enamel steel sheet and cured with hot air at a curing temperature of 100℃ for 120s to obtain a polymer pre-coated cold-rolled enamel steel sheet.

[0052] The main technical indicators of the polymer pre-coated cold-rolled enamel steel sheets obtained in each embodiment are shown in the table below:

[0053]

[0054] Note: Pinhole rate is the number of pinholes per square meter. Adhesion level is evaluated according to EN 10209 standard, with level 1 being the best and level 5 being the worst. Fish scale crackle refers to fish scale-like crackle defects.

[0055] Conclusion: Compared with uncoated cold-rolled enamel steel, the polymer-coated cold-rolled enamel steel sheet manufactured according to the manufacturing method of the present invention has significantly improved anti-pinhole performance, reduced pinhole rate by more than 60%, improved adhesion grade by 1-2 levels, and no scale bursting defects occur.

[0056] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for manufacturing a polymer-pre-coated cold-rolled enamel steel sheet, characterized in that, The polymer pre-coating on the surface of the cold-rolled enamel steel sheet is composed of the following raw materials by weight percentage: 20%–30% polymer, 5%–10% surfactant, 3%–6% corrosion inhibitor, and the remainder being water; the cold-rolled enamel steel sheet is an ultra-low carbon titanium-containing cold-rolled enamel steel sheet or an extremely low carbon high-oxygen cold-rolled enamel steel sheet; the polymer is one or two of water-based acrylic resin and water-based polyurethane resin; the surfactant is a nonionic surfactant, and the nonionic surfactant is one or two of polypropylene glycol and alkyl glucoside; the corrosion inhibitor is one or more of chromates, silicates, and nitrites. The manufacturing method of the polymer pre-coated cold-rolled enamel steel sheet includes: mixing polymer, surfactant and corrosion inhibitor according to weight percentage, adding to a container filled with water and stirring to obtain a polymer preparation; then coating the polymer preparation onto the surface of the cold-rolled enamel steel sheet by roller coating or dipping; and then curing the polymer preparation onto the surface of the cold-rolled enamel steel sheet; the curing is carried out by hot air curing, the curing temperature is 100-130℃, and the curing time is 90-150s.

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