Zinc-free primer, shipping container, powder protective coating, and construction process therefor

Abstract

A powder protective coating for a shipping container, comprising a container inner surface and a container outer surface. A primer layer uses high-solids oil paint, and a non-metal electrically conductive material is used to replace zinc metal. The material of a middle layer is an epoxy powder. A material of a surface layer of the container inner surface is an epoxy powder, and a material of a surface layer of the container outer surface is a polyester powder. The invention also relates to a construction process of the protective coating for a container, a shipping container, and a composition of the zinc-free primer applied to the container.

Description

Zinc-free primer, shipping container, powder protective coating and its application process

[0001] This application claims priority to a Chinese patent application filed with the Patent Office of China on August 16, 2023, with application number CN 2023110390474, entitled “A Shipping Container, a Powder Protective Coating for a Shipping Container, and a Construction Process Thereof,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to the field of material technology, and in particular to a zinc-free primer, a shipping container, a powder protective coating, and a construction process thereof. Background Art

[0003] Traditional container protection uses water-based paint, which consumes a large amount of organic solvents and produces a large amount of wastewater and waste residue. Pollution problems have always plagued the industry.

[0004] In the container sector, Jingyuan successfully developed a powder coating for containers in 2022. Following the official announcement in August 2022, the company produced nearly 30,000 TEUs of containers, establishing a group standard. Currently, the applicant is using a protective coating system for cold-rolled steel plates on containers. The first layer is a zinc-rich primer with a thickness of at least 35 microns, followed by a basecoat and topcoat.

[0005] Specifically, when using metal sheets, such as cold-rolled steel sheets, to produce containers, the steel sheets often have a small amount of oil on their surfaces due to manufacturing processes. Therefore, pre-treatment is required before cold working. First, the steel sheet surface is degreased (with acid or alkali solution), cleaned, dried (in the air or with hot air), shot blasted, and pre-coated with a zinc-rich primer. After pre-treatment, the cold working (punching, shearing, and press forming) process is completed, followed by steel structure welding, shot blasting of the welds, and then the entire container is painted (including spray painting and powder coating).

[0006] In actual use, containers produced using this spray coating method surpass those produced using conventional water-based paint in various performance aspects. However, the cold-rolled steel plate pre-treatment process for cold working presents the following challenges: 1. Wastewater disposal issues; 2. The zinc-rich primer is an oil-based paint (non-water-based), which can lead to VOC emissions. Both of these issues pose the potential for environmental non-compliance. Furthermore, the applicant has discovered that once corrosion occurs on shipping containers, which require high corrosion resistance, the corrosion spreads significantly.

[0007] Therefore, a new coating system and coating process are needed to solve the above problems.

[0008] Summary of the Invention

[0009] This application is proposed to alleviate or solve at least one aspect or at least one point of the above problems.

[0010] The present application provides a powder protective coating for a shipping container, wherein the container comprises an inner surface and an outer surface of the container; at least a portion of the container is made of a metal sheet;

[0011] in:

[0012] The metal sheet forming the inner surface of the container includes at least three coating layers: A1 layer, A2 layer, and A3 layer. The material of the A1 layer includes: high-solid oil-based paint and non-metallic conductive material; the A1 layer does not contain metallic zinc; the material of the A2 layer is epoxy powder; the material of the A3 layer is epoxy powder;

[0013] And / or, the metal sheet forming the outside of the container includes at least: a three-layer coating structure of layer B1, layer B2, and layer B3; the material of layer B1 includes: high-solid oil-based paint and non-metallic conductive material; layer B1 does not contain metallic zinc; the material of layer B2 is epoxy powder; and the material of layer B3 is polyester powder.

[0014] Optionally, the A1 layer does not contain zinc; and the B1 layer does not contain zinc.

[0015] Optionally, the A1 layer is formed by roll coating before the metal sheet is formed into a container; the A2 and A3 layers are formed by spraying after the container body is formed; and / or, the B1 layer is formed by roll coating before the metal sheet is formed into a container; the B2 and B3 layers are formed by spraying after the container body is formed.

[0016] Optionally, the thickness of the A1 layer is less than the thickness of the A2 and A3 layers; and / or the thickness of the B1 layer is less than the thickness of the B2 and B3 layers; optionally, the thickness of the A1 layer is less than 20 microns, more optionally less than 12 microns.

[0017] Optionally, the thickness of the A1 layer is 8-12 microns, the thickness of the A2 layer is 37-43 microns, and the thickness of the A3 layer is 38-43 microns;

[0018] And / or, the thickness of the B1 layer is 8-12 microns, the thickness of the B2 layer is 37-43 microns, and the thickness of the B3 layer is 44-46 microns.

[0019] Optionally, the solid content of the high-solid oil-based paint in the A1 layer is not less than 60%, and the content of the non-metallic conductive material is in the range of 0.5%-10% by weight of the high-solid oil-based paint;

[0020] And / or, the solid content of the high-solid oil-based paint in the B1 layer is not less than 60%, and the content of the non-metallic conductive material is in the range of 0.5%-10% by weight of the high-solid oil-based paint.

[0021] Optionally, the zinc content in the A1 and B1 layers is zero, and the thickness of the A1 layer is substantially the same as that of the B1 layer.

[0022] Optionally, the non-metallic conductive material in layers A1 and B1 is graphite, and the graphite content is approximately 2%.

[0023] Optionally, the solid content of the high-solid oil-based paint in layers A1 and B1 is 70%, and the content of the non-metallic conductive material is in the range of 5% by weight of the high-solid oil-based paint.

[0024] In addition, the present application also provides a construction process for a protective coating of a container, comprising the following steps:

[0025] Derusting and / or sanding sheet metal;

[0026] With hot coating, heat the paint or the plate before applying A1 layer and B1 layer;

[0027] Drying or air drying, wherein the air drying uses hot air;

[0028] Processing and welding metal sheets to form a box;

[0029] Sandblast the welds of the entire box;

[0030] A2 layer and B2 layer are sprayed; A3 layer and B3 layer are sprayed;

[0031] Solidification and cooling.

[0032] Optionally, when hot air is used for drying, the temperature of plates thicker than 4 mm after being heated by hot air shall not be lower than 85°C.

[0033] Optionally, before hot roller coating, the process also includes uniformly mixing the high-solid oil-based paint with the non-metallic conductive material.

[0034] Optionally, after the metal sheet is sandblasted, its surface roughness is between 15-35 microns.

[0035] The present application also provides a shipping container, comprising any one of the protective coatings described above; or, employing the construction process described above.

[0036] Optionally, the materials forming the A1 layer and the B1 layer include, by mass percentage, 25-30% of modified epoxy resin, 10-15% of anti-rust pigment, 3-5% of cyclohexanone, 8-10% of xylene, 3-6% of n-butanol, 8-20% of curing agent, and 0.5-10% of non-metallic conductive material, with the remainder being pigments and fillers.

[0037] Optionally, the non-metallic conductive material includes at least one of graphite, graphene and conductive mica.

[0038] Optionally, in terms of mass percentage, the epoxy powders of A2 and B2 both include: 25-50% polyester resin, 22-45% epoxy resin, 1-10% phenolic curing agent, 0.1-2.4% accelerator, 0.5-2% leveling agent, 0.1-2% degassing agent, 5-30% composite filler and 0.2-2% toughening agent, with the remainder being pigments and fillers.

[0039] Optionally, the polyester resin has an acid value of 34 to 76 mgKOH / g and a viscosity of 3000 to 6000 mPa.s; and / or

[0040] The epoxy value of the epoxy resin is 0.090-0.165eq / 100g, and the softening point is 87-105°C.

[0041] Optionally, in terms of mass percentage, the epoxy powder A3 includes 30-60% polyester resin, 20-36% epoxy resin, 0.5-1% leveling agent, 0.1-1% defoaming agent, 0.2-2% antioxidant 0.2-2% and 0.5-3% toughening agent, and the rest is pigment and filler.

[0042] Optionally, the polyester resin has an acid value of 34 to 76 mgKOH / g and a viscosity of 3000 to 6000 mPa.s; and / or

[0043] The epoxy value of the epoxy resin is 0.090-0.165eq / 100g, and the softening point is 87-105°C.

[0044] Optionally, in terms of mass percentage, the polyester powder of B3 includes 30-45% of high weather-resistant polyester resin, 22-35% of super weather-resistant polyester resin, 0-3.5% of triglycidyl isocyanurate, 0-2.5% of hydroxyalkylamide, 14-24% of blocked polyisocyanate, 0.5-1.5% of leveling agent, 0.1-3% of accelerator, 0.1-1% of defoaming agent, 0.5-3.2% of toughening agent, 0.2-2% of antioxidant and 2-25% of composite filler, and the rest is pigment filler.

[0045] Optionally, the acid value of the highly weather-resistant polyester is 29-34 mgKOH / g, and the viscosity is 4500-6000 mPa﹒ s;

[0046] The super weather-resistant polyester has a hydroxyl value of 100 to 120 mgKOH / g and a viscosity of 3200 to 4200 mPa﹒s.

[0047] The present application also provides a zinc-free primer for use in containers, which includes, in percentage by mass: 25-30% of modified epoxy resin, 10-15% of anti-rust pigment, 3-5% of cyclohexanone, 8-10% of xylene, 3-6% of n-butanol, 8-20% of curing agent, and 0.5-10% of non-metallic conductive material, with the remainder being pigments and fillers.

[0048] This application further refines and optimizes the powder coating system, developing a zinc-free pretreatment primer. This utilizes a high-solids oil-based paint and replaces metallic zinc with a non-metallic conductive material. This design reduces corrosion compared to existing coatings due to the absence of metallic zinc.

[0049] The first layer utilizes high-solids oil-based paint and non-metallic conductive materials, replacing metallic zinc. This ensures electrical conductivity, facilitating subsequent spraying. It also reduces corrosion. Furthermore, because the non-metallic conductive material and high-solids oil-based paint mix more thoroughly, the first layer can be thinner, resulting in superior corrosion resistance. Since the A1 layer is formed before container assembly, weldability is essential for subsequent assembly. The addition of non-metallic conductive materials enhances the A1 layer's conductivity to prevent any potential issues with welding.

[0050] Because it contains no metallic materials, its powder has better adhesion, making it more conducive to subsequent spraying. Practical verification shows that zinc-free pre-treatment primers fully meet the requirements for inter-process rust prevention. They exhibit superior adhesion to powder, exhibit better corrosion resistance than water-based paints, and possess welding performance comparable to zinc-rich primers. Furthermore, zinc-free pre-treatment primers are less expensive and lighter than zinc-rich primers.

[0051] The construction process of this application uses laser rust removal in pre-treatment to avoid the discharge of sewage, and uses high-solid paint to effectively reduce VOC emissions. Compared with the existing technology, its thickness is greatly reduced, saving materials and having good environmental protection effects.

[0052] This application breaks the current tradition of using zinc-rich primers in the container field, and creatively adopts zinc-free primers, so that the A1 layer and B1 layer do not contain zinc, and uses non-metallic conductive materials to ensure conductive properties. Therefore, when corrosion occurs, there is no zinc salt generation, thereby avoiding the separation between the bottom layer and the substrate caused by volume expansion, thereby reducing the corrosion expansion phenomenon and extending the service life.

[0053] Other features and advantages of the present disclosure will become apparent from the following detailed description, or may be learned in part by practice of the present disclosure.

[0054] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to make the contents of the present disclosure more clearly understood, the present disclosure is further described in detail below based on specific embodiments of the present disclosure in conjunction with the accompanying drawings, wherein:

[0056] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification, are used to explain the principles of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0057] FIG1 is an experimental sample of the anti-corrosion performance of Example 1 of the present application.

[0058] FIG2 shows the anti-corrosion performance experimental sample of Example 2 of the present application.

[0059] FIG3 shows the anti-corrosion performance experimental sample of Example 2 of the present application.

[0060] FIG4 shows the anti-corrosion performance experimental sample of comparative example 1.

[0061] FIG5 is an experimental sample of the anti-corrosion performance of Example 5 of the present application.

[0062] FIG6 is an experimental sample of the anti-corrosion performance of Example 6 of the present application.

[0063] FIG7 is an experimental sample of the anti-corrosion performance of Example 7 of the present application.

[0064] FIG8 is an experimental sample of the anti-corrosion performance of Example 11 of the present application.

[0065] FIG9 is an experimental sample of the anti-corrosion performance of Example 12 of the present application.

[0066] FIG10 is an experimental sample of the anti-corrosion performance of Example 13 of the present application.

[0067] FIG11 is an experimental sample of the anti-corrosion performance of comparative example 2.

[0068] FIG12 is an experimental sample of the anti-corrosion performance of comparative example 3. DETAILED DESCRIPTION

[0069] The following description of the embodiments of the present application with reference to the accompanying drawings is intended to explain the overall application concept of the present application and should not be understood as a limitation of the present application. In the present application, the same reference numerals represent the same or similar components.

[0070] The features described herein can be implemented in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein are provided to illustrate only some of the many possible ways to implement the methods, devices, and / or systems described herein, which will become clear after understanding the disclosure of this application.

[0071] Although terms such as "first," "second," and "third" may be used herein to describe various members, components, regions, layers, or sections, these members, components, regions, layers, or sections should not be limited by these terms. Instead, these terms are only used to distinguish one member, component, region, layer, or section from another member, component, region, layer, or section.

[0072] The terms used herein are only used to describe various examples and are not intended to limit the disclosure. Unless the context clearly indicates otherwise, the singular is intended to include the plural. The terms "comprise," "include," and "have" indicate the presence of the recited features, quantities, operations, components, elements, and / or combinations thereof, but do not preclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0073] In order to enable those skilled in the art to use the contents of this application, the following exemplary embodiments may be provided in conjunction with specific application scenarios, specific system, device and component parameters, and specific connection methods. However, for those skilled in the art, these embodiments are only examples, and the general principles defined herein can be applied to other embodiments and application scenarios without departing from the spirit and scope of this application.

[0074] The present application provides a powder protective coating for a shipping container, wherein the container comprises an inner surface and an outer surface of the container, and at least a portion of the container is made of sheet metal.

[0075] The metal sheet forming the inner surface of the container comprises at least three coating layers: A1 layer, A2 layer, and A3 layer. The material of the A1 layer comprises: high-solid oil-based paint and non-metallic conductive material; the A1 layer does not contain metallic zinc; the material of the A2 layer is epoxy powder; the material of the A3 layer is epoxy powder;

[0076] And / or, the metal sheet forming the outside of the container includes at least: a three-layer coating structure of layer B1, layer B2, and layer B3; the material of layer B1 includes: high-solid oil-based paint and non-metallic conductive material; layer B1 does not contain metallic zinc; the material of layer B2 is epoxy powder; and the material of layer B3 is polyester powder.

[0077] It should be noted that existing container manufacturing companies, primer suppliers, and powder suppliers are all in an upstream and downstream supply relationship, and generally the three are different production companies. In the current existing technology, containers generally use zinc-rich primer as the base coating, and powder suppliers basically do not make improvements or research on zinc-rich primers for containers. The main function of the primer is to provide temporary protection for the intermediate plate used in container production before the powder coating is applied. The corrosion resistance of container terminal products basically relies on the middle layer paint and topcoat to achieve corrosion protection. Therefore, when corrosion problems occur in container terminal products, container manufacturers generally believe that the corrosion is caused by the middle layer paint or topcoat. Therefore, when facing the overall coating solution formed by powder coating and container zinc-rich primer, it is difficult for technical personnel in this field to find that it is the problem of the zinc-rich primer composition that affects the anti-corrosion ability of the powder coating, and they will only think that there is a problem with the powder coating itself.

[0078] The applicant of this application has made an innovative discovery: After research and analysis, the applicant has discovered that the severe corrosion expansion of current shipping containers is caused by the use of zinc-rich primers. When corrosion occurs, a large amount of zinc powder in the zinc-rich primer transforms into zinc salts, which cause the primer to expand in volume. The single powder coating formed on the container is extremely dense and cannot accommodate the expanding zinc salts. This causes the powder coating to separate from the container, resulting in the entire powder coating "flaking." This "flaking" continues to extend as the zinc powder corrodes.

[0079] Zinc powder reacts with chloride ions in chloride to form zinc salt zinc chloride, that is, zinc ions.

[0080] Zinc ions continue to react in an environment of oxygen, water, and carbon dioxide to form basic zinc carbonate. Basic zinc carbonate is a powdery substance that is insoluble in water and alcohol.

[0081] The specific reaction formula is as follows:

[0082] Zn+2Cl-→ZnCl2,

[0083] Zn 2+ +O2+H2O+CO2→ZnCO3·Zn(OH)2.

[0084] At the same time, the applicant has discovered that zinc-rich primers, due to their zinc content, pose a risk of poor quality when combined with subsequent powder coatings compared to zinc-free systems. Therefore, the present application provides zinc-free A1 and / or B1 layers to eliminate the formation of zinc salts and thereby reduce corrosion.

[0085] The present application provides a zinc-free primer for use in containers. The zinc-free primer is a material that forms an A1 layer and a B1 layer.

[0086] Specifically, according to mass percentage, the zinc-free primer includes 25-30% modified epoxy resin, 10-15% anti-rust pigment, 3-5% cyclohexanone, 8-10% xylene, 3-6% n-butanol, 8-20% curing agent, and 0.5-10% non-metallic conductive material, and the rest is pigment filler.

[0087] The materials forming the A1 layer and the B1 layer include, by mass percentage, 25-30% of a modified epoxy resin, 10-15% of an anti-rust pigment, 3-5% of cyclohexanone, 8-10% of xylene, 3-6% of n-butanol, 8-20% of a curing agent, and 0.5-10% of a non-metallic conductive material, with the remainder being pigments and fillers.

[0088] The modified epoxy resin can be an isocyanate-modified epoxy resin, a silicone-acrylate-modified epoxy resin, a dimer-acid-modified epoxy resin, an acrylic-modified epoxy resin, a low-polymerization-degree-modified epoxy resin, or ZJ-101 epoxy-modified acrylic resin produced by Suzhou Shengjia Resin Co., Ltd.

[0089] The curing agent includes at least one of polyamide 650, modified polyamide, isocyanate trimer and triethylenetetramine.

[0090] The anti-rust pigment includes at least one of aluminum tripolyphosphate, zinc phosphate, zinc oxide, aluminum phosphate, zinc molybdate, and aluminum oxide.

[0091] The pigments and fillers in the A1 layer and the B1 layer include but are not limited to at least one of titanium dioxide, iron oxide red, iron oxide yellow, ultramarine, phthalocyanine blue, phthalocyanine green, medium chrome yellow, DPP red, permanent red, permanent violet, barium sulfate, silica powder, wollastonite, mica powder, glass powder, quartz powder, carbon black, and titanium dioxide.

[0092] The non-metallic conductive material includes at least one of graphite, graphene or conductive mica.

[0093] According to mass percentage, the epoxy powder of layer A2 and layer B2 includes 25-50% polyester resin, 22-45% epoxy resin, 1-10% phenolic curing agent, 0.1-2.4% accelerator, 0.5-2% leveling agent, 0.1-2% degassing agent, 5-30% composite filler and 0.2-2% toughening agent, and the rest is pigment filler.

[0094] The polyester resins of the A2 layer and the B2 layer have an acid value of 34 to 76 mgKOH / g and a viscosity of 3000 to 6000 mPa﹒s.

[0095] The epoxy value of the epoxy resin of the A2 layer and the B2 layer is 0.090 to 0.165 eq / 100 g, and the softening point is 87 to 105°C.

[0096] The phenolic curing agent can be the 969H06 phenolic curing agent produced by Daqing Qinglu Langrun Technology Co., Ltd. or other existing phenolic curing agents.

[0097] The accelerators of the A2 layer and the B2 layer include at least one of imidazoline, colorless cobalt, methyldiethanolamine, aminophenol, and 2,4,6-tris(dimethylaminomethyl)phenol.

[0098] The leveling agent of the A2 layer and the B2 layer includes at least one of polyacrylic acid, acrylic acid ester polymer, polyether polyester modified organic siloxane, acrylic acid, fluorine modified acrylic acid, phosphate modified acrylic acid, acrylic resin, urea formaldehyde resin and melamine formaldehyde resin.

[0099] The degassing agent of the A2 layer and the B2 layer includes at least one of benzoyl ketone and stearic acid.

[0100] The composite fillers of the A2 layer and the B2 layer include at least one of aluminum oxide, boron nitride, zinc oxide, mica powder and silicon dioxide.

[0101] The toughening agent of the A2 layer and the B2 layer includes at least one of nano-silicon dioxide, methyl methacrylate-butadiene-styrene terpolymer, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, triethyl phosphate, and tributyl phosphate.

[0102] The pigments and fillers of the A2 layer and the B2 layer include but are not limited to at least one of titanium dioxide, iron oxide red, iron oxide yellow, ultramarine, phthalocyanine blue, phthalocyanine green, medium chrome yellow, DPP red, permanent red, permanent violet, barium sulfate, silica powder, wollastonite, mica powder, glass powder, quartz powder, carbon black, and titanium dioxide.

[0103] According to mass percentage, the epoxy powder of the A3 layer includes 30-60% polyester resin, 20-36% epoxy resin, 0.5-1% leveling agent, 0.1-1% defoaming agent, 0.2-2% antioxidant and 0.5-3% toughening agent, and the rest is pigment and filler.

[0104] The polyester resin of the A3 layer has an acid value of 34 to 76 mgKOH / g and a viscosity of 3000 to 6000 mPa﹒s.

[0105] The epoxy value of the epoxy resin of the A3 layer is 0.090 to 0.165 eq / 100 g, and the softening point is 87 to 105°C.

[0106] The leveling agent of the A3 layer includes at least one of polyacrylic acid, acrylic acid ester polymer, polyether polyester modified organic siloxane, acrylic acid, fluorine modified acrylic acid, phosphate modified acrylic acid, acrylic resin, urea formaldehyde resin and melamine formaldehyde resin.

[0107] The defoaming agent of the A3 layer includes at least one of TEGO Foamex 825, TEGO Foamex 810, BYK-028, BYK-024, TEGO-902W, defoamer NXZ, BYK-022 defoamer from BYK Chemical, polydimethylsiloxane defoamer, AKN-3324, benzoin, BYK-066N and BYK085.

[0108] The antioxidant of the A3 layer includes at least one of B215 composite antioxidant, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,6-tert-butyl-4-methylphenol, bis(3,5-tert-butyl-4-hydroxyphenyl) sulfide and BASF antioxidant 1010.

[0109] The toughening agent of the A3 layer includes at least one of nano-silicon dioxide, methyl methacrylate-butadiene-styrene terpolymer, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, triethyl phosphate, and tributyl phosphate.

[0110] The pigments and fillers of the A3 layer include but are not limited to at least one of titanium dioxide, iron oxide red, iron oxide yellow, ultramarine, phthalocyanine blue, phthalocyanine green, medium chrome yellow, DPP red, permanent red, permanent violet, barium sulfate, silica powder, wollastonite, mica powder, glass powder, quartz powder, carbon black, and titanium dioxide.

[0111] In terms of mass percentage, the polyester powder of the B3 layer includes 30-45% of high weather-resistant polyester resin, 22-35% of super weather-resistant polyester resin, 0-3.5% of triglycidyl isocyanurate, 0-2.5% of hydroxyalkylamide, 14-24% of blocked polyisocyanate, 0.5-1.5% of leveling agent, 0.1-3% of accelerator, 0.1-1% of defoaming agent, 0.5-3.2% of toughening agent, 0.2-2% of antioxidant and 2-25% of composite filler, and the rest is pigment filler.

[0112] The acid value of high weather-resistant polyester is 29-34 mgKOH / g, and the viscosity is 4500-6000 mPa﹒ s.

[0113] The hydroxyl value of super weather-resistant polyester is 100-120 mgKOH / g, and the viscosity is 3200-4200 mPa﹒s.

[0114] Triglycidyl isocyanurate is referred to as TGIC.

[0115] Hydroxyalkylamide is referred to as HAA.

[0116] The blocked polyisocyanate may be any one or more of EVONIK's brands B1400, BF1540 and BF1320.

[0117] The leveling agent of the B3 layer includes at least one of polyacrylic acid, acrylic acid ester polymer, polyether polyester modified organic siloxane, acrylic acid, fluorine modified acrylic acid, phosphate modified acrylic acid, acrylic resin, urea formaldehyde resin and melamine formaldehyde resin.

[0118] The accelerator of the B3 layer includes at least one of imidazoline, colorless cobalt, methyldiethanolamine, aminophenol, and 2,4,6-tris(dimethylaminomethyl)phenol.

[0119] The defoamer of layer B3 includes at least one of TEGO Foamex 825, TEGO Foamex 810, BYK-028, BYK-024, TEGO-902W, defoamer NXZ, BYK-022 defoamer from BYK Chemical, polydimethylsiloxane defoamer, AKN-3324, benzoin, BYK-066N and BYK085.

[0120] The toughening agent of the B3 layer includes at least one of nano-silicon dioxide, methyl methacrylate-butadiene-styrene terpolymer, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, triethyl phosphate, and tributyl phosphate.

[0121] The antioxidant in the B3 layer includes at least one of B215 composite antioxidant, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,6-tert-butyl-4-methylphenol, bis(3,5-tert-butyl-4-hydroxyphenyl) sulfide and BASF antioxidant 1010.

[0122] The composite filler of the B3 layer includes at least one of aluminum oxide, boron nitride, zinc oxide, mica powder and silicon dioxide.

[0123] The pigments and fillers of the B3 layer are inorganic pigments and fillers, including but not limited to at least one of titanium dioxide, iron oxide red, iron oxide yellow, ultramarine, phthalocyanine blue, phthalocyanine green, medium chrome yellow, DPP red, permanent red, permanent violet, barium sulfate, silica powder, wollastonite, mica powder, glass powder, quartz powder, carbon black, and titanium dioxide.

[0124] In the entire protective layer, the epoxy group of the A1 layer can react with the polyester carboxyl group in the A2 layer to achieve a connection between the A1 and A2 layers through chemical bonding. The carboxyl group of the polyester resin in the A2 layer can react with the epoxy group in the A3 layer to achieve a connection between the A2 and A3 layers through chemical bonding.

[0125] The epoxy group in the B1 layer can react with the polyester carboxyl group in the B2 layer to connect the B1 and B2 layers through chemical bonding. The carboxyl group of the polyester resin in the B2 layer can react with the curing agent in the B3 layer to connect the B2 and B3 layers through chemical bonding.

[0126] Therefore, the interlayer bonding of the entire protective coating is strong. In the adhesion pull-off test, the breaking strength reached over 10Mpa, and the entire protective coating partially detached from the substrate at once, with no interlayer detachment.

[0127] After being formed on the substrate, the A1 and B1 layers protect the substrate through physical isolation, providing temporary protection. The interior of the container product is protected from corrosion by the A2 and A3 layers, while the exterior of the container is protected from corrosion by the B2 and B3 layers.

[0128] The A1 layer is formed by coating the metal sheet before it is formed into a container, while the A2 and A3 layers are formed by spraying after the container body is formed.

[0129] And / or, layer B1 is formed by coating the metal sheet before forming the container, and layers B2 and B3 are formed by spraying after forming the container body.

[0130] The thickness of the A1 layer is smaller than that of the A2 and A3 layers.

[0131] Preferably, the thickness of the A1 layer is 8-12 microns. When the thickness is less than 8 microns, the corrosion expansion performance is poor. When the thickness is greater than 12 microns, the cost increases. The thickness of the A2 layer is 37-43 microns, and the thickness of the A3 layer is 38-43 microns. When the thickness of the A2 layer is less than 37 microns, the corrosion resistance is poor. When the thickness of the A2 layer is greater than 43 microns, the cost increases. When the thickness of the A3 layer is less than 38 microns, the corrosion resistance is poor. When the thickness of the A3 layer is greater than 43 microns, the cost increases.

[0132] And / or, the thickness of layer B1 is smaller than the thickness of layers B2 and B3.

[0133] Preferably, the thickness of the B1 layer is 8-12 microns, the thickness of the B2 layer is 37-43 microns, and the thickness of the B3 layer is 44-46 microns.

[0134] The solid content of the high-solid oil-based paint in the A1 layer is not less than 60%, and the content of the non-metallic conductive material is in the range of 0.5%-10% of the weight of the high-solid oil-based paint.

[0135] And / or, the solid content of the high-solid oil-based paint in the B1 layer is not less than 60%, and the content of the non-metallic conductive material is in the range of 0.5%-10% by weight of the high-solid oil-based paint.

[0136] The non-metallic conductive material in the A1 and B1 layers is graphite, and the graphite content is approximately 2%.

[0137] The solid content ratio of the high-solid oil-based paint in the A1 and B1 layers is 70%, and the content of the non-metallic conductive material is in the range of 5% by weight of the high-solid oil-based paint.

[0138] The present application also provides a method for applying a protective coating to engineering equipment, comprising the following steps:

[0139] S1. Laser rust removal and / or sandblasting of metal sheets.

[0140] S2. With hot coating, heat the paint or the plate before applying A1 layer and B1 layer.

[0141] Specifically, when the thickness of the metal plate is greater than 4 mm, the metal plate is heated to a temperature greater than or equal to 85° C.

[0142] When the thickness of the metal sheet is less than 4mm, it is usually heated to 85℃.

[0143] The temperature of the heated coating was 40°C.

[0144] S3, drying or air drying, wherein the air drying adopts hot air.

[0145] S4. Processing and welding the metal plates to form a box.

[0146] S5. Sandblast the welds of the entire box.

[0147] S6, A2 layer, and B2 layer are sprayed; A3 layer and B3 layer are sprayed.

[0148] S7, solidification and cooling.

[0149] The present application also provides a shipping container, comprising the above-mentioned protective coating; or, adopting the above-mentioned construction process.

[0150] The above-mentioned protective coating is introduced below through various embodiments.

[0151] Example 1:

[0152] Step 1: Derust the metal sheet and perform fine sandblasting to a surface roughness of 15-35 microns; laser rust removal is used for rust removal, which can avoid pollution compared to existing rust removal methods.

[0153] Step 2: Roll coating, use high-solid oil-based paint to apply the first layer of coating to the metal plate, the thickness of the first layer is 10 microns; the solid content ratio of the high-solid oil-based paint is more than 60%, 2% graphite is added, and it is fully mixed; it can be rolled hot, and the temperature of hot rolling is above 40 degrees.

[0154] Step 3: Air-dry the coated metal sheet;

[0155] Step 4: Process the air-dried metal sheet into a box;

[0156] Step 5: Remove the oxidation layer from the weld seams of the entire box;

[0157] Step 6: Two layers of powder spraying, first spray the base powder, then spray the flour powder; the base powder inside the box is 40 microns, which is epoxy powder; the base powder outside the box is 40 microns, which is epoxy powder; the flour outside the box is 45 microns, which is polyester powder, and the flour inside the box is 40 microns, which is epoxy powder;

[0158] Step 7: Solidify and cool.

[0159] The container metal sheet of the present application can be a cold-rolled steel plate or a hot-rolled steel plate, and the protective coating system includes three layers, among which the first layer, the primer layer is about 10 microns thick, and the thickness of the primer layer reduces the high-solid oil-based paint; compared with the existing 35-micron primer layer, it greatly reduces the use of oil-based paint and can significantly reduce VOC emissions.

[0160] Optionally, the solid content ratio of the high-solid oil-based paint of the present application is not less than 60%. The present application adopts a solid content ratio of not less than 60%, which can greatly reduce VOC emissions compared to the existing solid content ratio of about 40%.

[0161] The zinc content of this application is zero; non-metallic conductive materials are used to replace the original zinc. On the one hand, the conductivity of non-metallic materials is utilized, and on the other hand, the non-metallic conductive materials themselves are less polluting. The non-metallic conductive materials can be graphite, etc. If graphite is used to replace the original zinc material, on the one hand, the conductivity can be guaranteed, and on the other hand, the corrosion resistance can be improved. Optionally, the proportion of non-metallic conductive materials in this application is between 0.5% and 10%, and the surface resistance of the primer layer is 102 ohms to 109 ohms. In this example, the solid content is 70% and the proportion of non-metallic conductive materials is 5%.

[0162] The second layer is approximately 40 microns thick and is made of epoxy powder. It uses materials that meet FDA requirements. Since the thickness of the first layer is significantly less than that of the existing first layer, in order to ensure the quality of the coating, this application will appropriately increase the thickness of the second layer to 40 microns;

[0163] The third layer is about 45 microns thick on the outside of the box and is polyester powder; the inside of the box is about 40 microns thick and is epoxy powder; it meets FDA requirements; this application appropriately increases the spray thickness on the outside of the box to further ensure its anti-corrosion effect after coating.

[0164] The powder coating of this application not only has excellent environmental performance, but also has comprehensive advantages over traditional coating processes in terms of process stability and coating quality.

[0165] Example 2:

[0166] The steps of Example 2 are the same as those of Example 1, except that the thickness of the first coating layer is 10 microns, the thickness of the second layer is 43 microns, the thickness of the third layer is 43 microns inside the box and 46 microns outside the box.

[0167] Example 3:

[0168] The steps of Example 3 are the same as those of Example 1, except that the thickness of the first coating layer is 12 microns, the thickness of the second layer is 41 microns, the thickness of the third layer is 41 microns inside the box and 44 microns outside the box.

[0169] Example 4

[0170] The protective coating in this embodiment is an 8-micron A1 layer, a 37-micron A2 layer, and a 38-micron A3 layer.

[0171] Among them, the materials of the A1 layer include, by mass percentage: 25% isocyanate-modified epoxy resin, 15% anti-rust pigment aluminum tripolyphosphate, 5% cyclohexanone, 10% xylene, 6% n-butanol, 8% curing agent-modified polyamide, 10% non-metallic conductive material graphite, and 21% pigment filler titanium dioxide.

[0172] The epoxy powder of the A2 layer includes, by mass percentage, 50% polyester resin (acid value of 34 mgKOH / g, viscosity of 3000 mPa﹒s), 26% epoxy resin (epoxy value 0.165eq / 100g, softening point of 87°C), 2% phenolic curing agent (969H06 phenolic curing agent produced by Daqing Qinglu Langrun Technology Co., Ltd.), 0.1% accelerator methyldiethanolamine, 0.5% leveling agent polyacrylic acid, 0.1% degassing agent dibenzoyl ketone, 5% composite filler silica and 0.2% toughening agent nanosilica, and 16.1% pigment filler iron red.

[0173] The epoxy powder of the A3 layer includes, by mass percentage, 60% polyester resin (acid value 34mgKOH / g, viscosity 3000mPa﹒s), 20% epoxy resin (epoxy value 0.165eq / 100g, softening point 87℃), 1% leveling agent polyacrylic acid, 0.1% defoaming agent TEGO Foamex 825, 0.2% antioxidant B215 composite antioxidant, 0.5% toughening agent nano-silica, and 18.2% pigment filler phthalocyanine blue.

[0174] Example 5

[0175] The protective coating in this embodiment is a 12 micron A1 layer, a 43 micron A2 layer, and a 43 micron A3 layer.

[0176] Among them, the materials of the A1 layer include, by mass percentage: 30% silicone acrylic modified epoxy resin, 10% anti-rust pigment zinc phosphate, 3% cyclohexanone, 8% xylene, 3% n-butanol, 20% curing agent polyamide 650 and 0.5% non-metallic conductive material graphene, and 25.5% is iron red pigment filler.

[0177] The epoxy powder of the A2 layer includes, by mass percentage, 25% polyester resin (acid value of 34 mgKOH / g, viscosity of 6000 mPa﹒s), 45% epoxy resin (epoxy value of 0.160 eq / 100 g, softening point of 95°C), 10% phenolic curing agent (969H06 phenolic curing agent produced by Daqing Qinglu Langrun Technology Co., Ltd.), 2.4% accelerator aminophenol, 2% leveling agent acrylic polymer, 2% degassing agent stearic acid, 5% composite filler boron nitride and 2% toughening agent methyl methacrylate-butadiene-styrene terpolymer, and 6.6% pigment filler phthalocyanine blue.

[0178] The epoxy powder of the A3 layer includes, by mass percentage, 30% polyester resin (acid value 76mgKOH / g, viscosity 6000mPa﹒s), 36% epoxy resin (epoxy value 0.090eq / 100g, softening point 105℃), 1% leveling agent acrylic polymer, 1% defoaming agent BYK-028, 2% antioxidant β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and 3% toughening agent dimethyl phthalate, and 27% pigment filler ultramarine.

[0179] Example 6

[0180] The protective coating in this embodiment is a 10 micron A1 layer, a 40 micron A2 layer, and a 40 micron A3 layer.

[0181] Among them, the materials of the A1 layer include, by mass percentage: 28% dimer acid modified epoxy resin, 12% anti-rust pigment zinc oxide, 4% cyclohexanone, 9% xylene, 5% n-butanol, 15% curing agent isocyanate trimer and 5% non-metallic conductive material conductive mica, and 22% pigment filler permanent purple.

[0182] The epoxy powder of the A2 layer includes, by mass percentage, 30% polyester resin (acid value of 54 mgKOH / g, viscosity of 4500 mPa﹒s), 40% epoxy resin (epoxy value of 0.12 eq / 100 g, softening point of 105°C), 5% phenolic curing agent (969H06 phenolic curing agent produced by Daqing Qinglu Langrun Technology Co., Ltd.), 1% accelerator 2,4,6-tris(dimethylaminomethyl)phenol, 1% leveling agent fluorine-modified acrylic acid, 0.5% deaerator dibenzoyl ketone, 0.5% deaerator stearic acid, 15% composite filler alumina, 1% toughening agent diethyl phthalate, and 6% pigment filler phthalocyanine blue.

[0183] The epoxy powder of the A3 layer includes, by mass percentage, 45% polyester resin (acid value 54mgKOH / g, viscosity 4500mPa﹒s), 30% epoxy resin (epoxy value 0.110eq / 100g, softening point 100℃), 0.5% leveling agent phosphate-modified acrylic acid, 0.5% defoaming agent BYK-024, 1% antioxidant 2,6-tert-butyl-4-methylphenol and 2% toughening agent dibutyl phthalate, and 21% pigment filler mica powder and ultramarine.

[0184] Example 7

[0185] The difference between this embodiment and embodiment 6 lies in the thickness of each layer, wherein the thickness of the A1 layer is 11 microns, the thickness of the A2 layer is 41 microns, and the thickness of the A3 layer is 41 microns.

[0186] Example 8

[0187] The protective coating in this embodiment is an A1 layer of 9 microns, an A2 layer of 38 microns, and an A3 layer of 39 microns.

[0188] Among them, the materials of the A1 layer include, by mass percentage: 28% acrylic modified epoxy resin, 10% anti-rust pigment zinc molybdate, 3% cyclohexanone, 8% xylene, 3% n-butanol, 20% curing agent triethylenetetramine and 2.5% non-metallic conductive material graphene, and 25.5% is the pigment filler iron yellow.

[0189] The epoxy powder of the A2 layer includes, by mass percentage, 25% polyester resin (acid value 76 mgKOH / g, viscosity 6000 mPB﹒s), 45% epoxy resin (epoxy value 0.090eq / 100g, softening point 105°C), 3% phenolic curing agent (969H06 phenolic curing agent produced by Daqing Qinglu Langrun Technology Co., Ltd.), 2.4% accelerator imidazoline, 2% leveling agent acrylic polymer, 2% degassing agent stearic acid, 5% composite filler silica and 2% toughening agent methyl methacrylate-butadiene-styrene terpolymer, and 13.6% pigment filler phthalocyanine green.

[0190] The epoxy powder of the A3 layer includes, by mass percentage, 45% polyester resin (acid value 54mgKOH / g, viscosity 4500mPa﹒s), 30% epoxy resin (epoxy value 0.110eq / 100g, softening point 100℃), 0.5% leveling agent phosphate-modified acrylic acid, 0.5% defoaming agent BYK-022, 1% antioxidant 2,6-tert-butyl-4-methylphenol and 2% toughening agent tributyl phosphate, and 21% pigment filler mica powder and ultramarine.

[0191] Example 9

[0192] The protective coating in this embodiment is an 11 micron A1 layer, a 41 micron A2 layer, and a 41 micron A3 layer.

[0193] Among them, the materials of the A1 layer include, by mass percentage: 25% low-polymerization modified epoxy resin, 15% anti-rust pigment alumina, 5% cyclohexanone, 10% xylene, 6% n-butanol, 4% curing agent isocyanate trimer, 4% curing agent polyamide 650, 10% non-metallic conductive material graphene, and 21% color filler silicon powder.

[0194] The epoxy powder of the A2 layer includes, by mass percentage, 25% polyester resin (acid value 76 mgKOH / g, viscosity 3000 mPa﹒s), 22% epoxy resin (epoxy value 0.165eq / 100g, softening point 87°C), 1% phenolic curing agent (969H06 phenolic curing agent produced by Daqing Qinglu Langrun Technology Co., Ltd.), 0.1% accelerator colorless cobalt, 0.5% leveling agent polyacrylic acid, 0.1% degassing agent dibenzoyl ketone, 30% composite filler boron nitride and 0.2% toughening agent nano-silica, and 21.1% pigment filler iron red.

[0195] The epoxy powder of the A3 layer includes, by mass percentage, 39% polyester resin (acid value 60mgKOH / g, viscosity 5000mPa﹒s), 35% epoxy resin (epoxy value 0.120eq / 100g, softening point 100℃), 0.5% leveling agent phosphate-modified acrylic acid, 0.5% defoaming agent TEGO-902W, 1% antioxidant 2,6-tert-butyl-4-methylphenol and 2% toughening agent dibutyl phthalate, and 23% pigment filler mica powder and ultramarine.

[0196] Example 10

[0197] The protective coating in this embodiment is an 8-micron B1 layer, a 37-micron B2 layer, and a 44-micron B3 layer.

[0198] Among them, the materials of the B1 layer include, by mass percentage: 25% isocyanate-modified epoxy resin, 15% anti-rust pigment aluminum tripolyphosphate, 5% cyclohexanone, 10% xylene, 6% n-butanol, 8% curing agent-modified polyamide, 10% non-metallic conductive material graphite, and 21% pigment filler titanium dioxide.

[0199] The epoxy powder of the B2 layer includes, by mass percentage, 50% polyester resin (acid value of 34 mgKOH / g, viscosity of 3000 mPa﹒s), 26% epoxy resin (epoxy value of 0.165eq / 100g, softening point of 87°C), 2% phenolic curing agent (969H06 phenolic curing agent produced by Daqing Qinglu Langrun Technology Co., Ltd.), 0.1% accelerator methyldiethanolamine, 0.5% leveling agent polyacrylic acid, 0.1% degassing agent dibenzoyl ketone, 5% composite filler silica and 0.2% toughening agent nanosilica, and 16.1% pigment filler iron red.

[0200] The polyester powder of the B3 layer includes 30% high weather-resistant polyester resin with an acid value of 32 mgKOH / g and a viscosity of 5000 mPa﹒s, 35% super weather-resistant polyester resin with a hydroxyl value of 100 mgKOH / g and a viscosity of 3200 mPa﹒s, 2.3% curing agent TGIC, 24% curing agent B1400, 0.5% leveling agent polyether polyester modified organic siloxane, 0.1% accelerator methyldiethanolamine, 0.1% BYK-022 defoaming agent, 0.5% toughening agent dimethyl phthalate, 0.2% antioxidant 2,6-tert-butyl-4-methylphenol and 5% composite filler boron nitride, 2.3% pigment filler phthalocyanine blue.

[0201] Example 11

[0202] The protective coating in this embodiment is a 12 micron B1 layer, a 43 micron B2 layer, and a 45 micron B3 layer.

[0203] Among them, the materials of the B1 layer include, by mass percentage: 30% silicone acrylic modified epoxy resin, 10% anti-rust pigment zinc phosphate, 3% cyclohexanone, 8% xylene, 3% n-butanol, 20% curing agent polyamide 650 and 0.5% non-metallic conductive material graphene, and 25.5% is iron oxide red pigment filler.

[0204] The epoxy powder of the B2 layer includes, by mass percentage, 25% polyester resin (acid value of 34 mgKOH / g, viscosity of 6000 mPa﹒s), 45% epoxy resin (epoxy value of 0.160eq / 100g, softening point of 95°C), 10% phenolic curing agent (969H06 phenolic curing agent produced by Daqing Qinglu Langrun Technology Co., Ltd.), 2.4% accelerator aminophenol, 2% leveling agent acrylic polymer, 2% degassing agent stearic acid, 5% composite filler boron nitride and 2% toughening agent methyl methacrylate-butadiene-styrene terpolymer, and 6.6% pigment filler phthalocyanine blue.

[0205] The polyester powder of the B3 layer includes 30% high weather-resistant polyester resin with an acid value of 32 mgKOH / g and a viscosity of 5000 mPa﹒s, 35% super weather-resistant polyester resin with a hydroxyl value of 110 mgKOH / g and a viscosity of 3800 mPa﹒s, 2.3% curing agent TGIC, 24% curing agent B1540, 0.5% leveling agent polyether polyester modified organic siloxane, 0.1% accelerator methyldiethanolamine, 0.1% BYK-022 defoaming agent, 0.5% toughening agent dimethyl phthalate, 0.2% antioxidant 2,6-tert-butyl-4-methylphenol and 3% composite filler silica, 4.3% pigment filler phthalocyanine blue.

[0206] Example 12

[0207] The protective coating in this embodiment is a 12 micron B1 layer, a 43 micron B2 layer, and a 46 micron B3 layer.

[0208] Among them, the materials of the B1 layer include, by mass percentage: 30% silicone acrylic modified epoxy resin, 10% anti-rust pigment aluminum tripolyphosphate, 3% cyclohexanone, 8% xylene, 3% n-butanol, 20% curing agent polyamide 650 and 0.5% non-metallic conductive material graphene, and 25.5% is iron oxide red pigment filler.

[0209] The epoxy powder of the B2 layer includes, by mass percentage, 25% polyester resin (acid value 76 mgKOH / g, viscosity 6000 mPB﹒s), 45% epoxy resin (epoxy value 0.090eq / 100g, softening point 105°C), 3% phenolic curing agent (969H06 phenolic curing agent produced by Daqing Qinglu Langrun Technology Co., Ltd.), 2.4% accelerator imidazoline, 2% leveling agent acrylic polymer, 2% degassing agent stearic acid, 5% composite filler silica and 2% toughening agent methyl methacrylate-butadiene-styrene terpolymer, and 13.6% pigment filler phthalocyanine green.

[0210] The polyester powder of the B3 layer includes 45% high weather-resistant polyester resin with an acid value of 29 mgKOH / g and a viscosity of 4500 mPa﹒s, 22% super weather-resistant polyester resin with a hydroxyl value of 120 mgKOH / g and a viscosity of 4200 mPa﹒s, 2.7% curing agent TGIC, 0.5% curing agent HAA, 14% curing agent B1320, 1.5% leveling agent polyether polyester modified organic siloxane, 0.1% accelerator methyldiethanolamine, 0.1% defoaming agent TEGO-902W, 0.5% toughening agent tributyl phosphate, 0.2% BASF antioxidant 1010 and 11% composite filler boron nitride, 2.9% pigment filler phthalocyanine blue.

[0211] Example 13

[0212] The protective coating in this embodiment is a 10 micron B1 layer, a 40 micron B2 layer, and a 45 micron B3 layer.

[0213] Among them, the materials of the B1 layer include, by mass percentage: 28% dimer acid modified epoxy resin, 12% anti-rust pigment zinc oxide, 4% cyclohexanone, 9% xylene, 5% n-butanol, 15% curing agent isocyanate trimer and 5% non-metallic conductive material conductive mica, and 22% pigment filler permanent purple.

[0214] The epoxy powder of the B2 layer includes, by mass percentage, 30% polyester resin (acid value of 70 mgKOH / g, viscosity of 4500 mPB﹒s), 40% epoxy resin (epoxy value of 0.120eq / 100g, softening point of 102°C), 3% phenolic curing agent (969H06 phenolic curing agent produced by Daqing Qinglu Langrun Technology Co., Ltd.), 1% accelerator 2,4,6-tris(dimethylaminomethyl)phenol, 1% leveling agent fluorine-modified acrylic acid, 0.5% deaerator dibenzoyl ketone, 0.5% deaerator stearic acid, 15% composite filler alumina, 1% toughening agent diethyl phthalate, and 6% pigment filler phthalocyanine blue.

[0215] The polyester powder of the B3 layer includes 38% high weather-resistant polyester resin with an acid value of 34 mgKOH / g and a viscosity of 6000 mPa﹒s, 25% super weather-resistant polyester resin with a hydroxyl value of 111 mgKOH / g and a viscosity of 3600 mPa﹒s, 2.5% curing agent HAA, 15% curing agent B1400, 0.5% leveling agent polyether polyester modified organic siloxane, 3% accelerator, 1% defoaming agent polydimethylsiloxane, 3.2% toughening agent triethyl phosphate, 2% antioxidant bis (3,5-tertiary butyl-4-hydroxyphenyl) sulfide and 6% composite filler mica powder, 4.3% pigment filler phthalocyanine blue.

[0216] Example 14

[0217] The difference between this embodiment and embodiment 13 lies in the thickness of each layer, wherein the thickness of the B1 layer is 11 microns, the thickness of the B2 layer is 41 microns, and the thickness of the B3 layer is 41 microns.

[0218] Example 15

[0219] The protective coating in this embodiment is an 8-micron B1 layer, a 37-micron B2 layer, and a 44-micron B3 layer.

[0220] Among them, the materials of the B1 layer include, by mass percentage: 25% low-polymerization modified epoxy resin, 15% anti-rust pigment alumina, 5% cyclohexanone, 10% xylene, 6% n-butanol, 4% curing agent isocyanate trimer, 4% curing agent polyamide 650, 10% non-metallic conductive material graphene, and 21% color filler silicon powder.

[0221] The epoxy powder of the B2 layer includes, by mass percentage, 25% polyester resin (acid value of 38 mgKOH / g, viscosity of 3000 mPa﹒s), 22% epoxy resin (epoxy value of 0.165eq / 100g, softening point of 87°C), 1% phenolic curing agent (969H06 phenolic curing agent produced by Daqing Qinglu Langrun Technology Co., Ltd.), 0.1% accelerator methyldiethanolamine, 0.5% leveling agent polyacrylic acid, 0.1% degassing agent dibenzoyl ketone, 30% composite filler boron nitride and 0.2% toughening agent nano-silica, and 21.1% pigment filler iron red.

[0222] The polyester powder of the B3 layer includes 30% high weather-resistant polyester resin with an acid value of 32 mgKOH / g and a viscosity of 5000 mPa﹒s, 22% super weather-resistant polyester resin with a hydroxyl value of 100 mgKOH / g and a viscosity of 3200 mPa﹒s, 3.5% curing agent TGIC, 14% curing agent B1400, 0.5% leveling agent polyether polyester modified organic siloxane, 0.1% accelerator methyldiethanolamine, 0.1% BYK-022 defoaming agent, 0.5% toughening agent dimethyl phthalate, 0.2% antioxidant 2,6-tert-butyl-4-methylphenol and 25% composite filler boron nitride, 4.1% pigment filler phthalocyanine blue.

[0223] Comparative Example 1:

[0224] The metal surfaces are first degreased, cleaned, dried, and shot-blasted, with a 35-micron zinc-rich primer applied. After this pretreatment, cold working (punching, shearing, and pressing) is performed, followed by steel structure welding. The welds are shot-blasted before the entire box is painted. A second coat of 35-micron midcoat is applied, followed by a third coat of 40-micron topcoat.

[0225] Comparative Example 2

[0226] The protective coating is a 10 micron B1 layer, a 40 micron B2 layer and a 40 micron B3 layer.

[0227] The B1 layer is an oil-based epoxy zinc-rich primer (DWB ZINC 30) produced by Jiangsu DWB Paint Co., Ltd.

[0228] The epoxy powder of the B2 layer includes, by mass percentage, 30% polyester resin (acid value of 70 mgKOH / g, viscosity of 4500 mPB﹒s), 40% epoxy resin (epoxy value of 0.120eq / 100g, softening point of 102°C), 3% phenolic curing agent (969H06 phenolic curing agent produced by Daqing Qinglu Langrun Technology Co., Ltd.), 1% accelerator 2,4,6-tris(dimethylaminomethyl)phenol, 1% leveling agent fluorine-modified acrylic acid, 0.5% deaerator dibenzoyl ketone, 0.5% deaerator stearic acid, 15% composite filler alumina, 1% toughening agent diethyl phthalate, and 6% pigment filler phthalocyanine blue.

[0229] The polyester powder of the B3 layer includes 45% high weather-resistant polyester resin with an acid value of 29 mgKOH / g and a viscosity of 4500 mPa﹒s, 22% super weather-resistant polyester resin with a hydroxyl value of 120 mgKOH / g and a viscosity of 4200 mPa﹒s, 3.5% curing agent TGIC, 14% curing agent B1400, 1.5% leveling agent polyether polyester modified organic siloxane, 0.1% accelerator methyldiethanolamine, 0.1% defoaming agent TEGO-902W, 0.5% toughening agent tributyl phosphate, 0.2% BASF antioxidant 1010 and 11% composite filler boron nitride, and 2.6% pigment filler phthalocyanine blue.

[0230] Comparative Example 3

[0231] The protective coating is a 10 micron A1 layer, a 40 micron A2 layer and a 40 micron A3 layer.

[0232] The A1 layer is an oil-based epoxy zinc-rich primer (DWB ZINC 30) produced by Jiangsu DWB Paint Co., Ltd.

[0233] The epoxy powder of the A2 layer includes, by mass percentage, 30% polyester resin (acid value 70mgKOH / g, viscosity 4500mPa﹒s), 40% epoxy resin (epoxy value 0.120eq / 100g, softening point 102℃), 3% phenolic curing agent, 1% accelerator 2,4,6-tris(dimethylaminomethyl)phenol, 1% leveling agent fluorine-modified acrylic acid, 0.5% degassing agent dibenzoyl ketone, 0.5% degassing agent stearic acid, 15% composite filler alumina, 1% toughening agent diethyl phthalate, and 6% pigment filler phthalocyanine blue.

[0234] The epoxy powder of the A3 layer includes, by mass percentage, 45% polyester resin (acid value 54mgKOH / g, viscosity 4500mPa﹒s), 30% epoxy resin (epoxy value 0.110eq / 100g, softening point 100℃), 0.5% leveling agent phosphate-modified acrylic acid, 0.5% defoaming agent BYK-024, 1% antioxidant 2,6-tert-butyl-4-methylphenol and 2% toughening agent dibutyl phthalate, and 21% pigment filler mica powder and ultramarine.

[0235] Comparative Example 4

[0236] The metal surfaces are first degreased, cleaned, dried, and shot-blasted, with a 10-micron zinc-rich primer applied. After this pretreatment, the steel is cold-formed (punching, shearing, and pressing), welded, and the welds shot-blasted before the entire box is painted. A second coat of 20-micron intermediate water-based epoxy zinc-rich paint is applied, followed by a third coat of 50-micron topcoat.

[0237] Among them, the zinc-rich primer uses DWep ZINC 500 produced by Jiangsu Dwep Paint Co., Ltd.

[0238] The intermediate water-based epoxy zinc-rich paint adopts DWB AC PRIMER produced by Jiangsu Derwei Paint Co., Ltd.

[0239] The topcoat is DWB AC INTERI0R from Jiangsu Derwei Paint Co., Ltd.

[0240] Comparative Example 5

[0241] The metal sheet surface is first degreased, cleaned, dried, and shot-blasted, with a 10-micron zinc-rich primer applied. After this pretreatment, the steel structure undergoes cold working (punching, shearing, and forming), followed by structural welding. The welds are shot-blasted before the entire box is painted. A second coat of 20-micron water-based epoxy zinc-rich paint is applied, followed by a third coat of 50-micron intermediate paint, and a fourth coat of 40-micron polyurethane topcoat.

[0242] Among them, the zinc-rich primer uses DWep ZINC 500 produced by Jiangsu Dwep Paint Co., Ltd.

[0243] The intermediate water-based epoxy zinc-rich paint adopts DWB AC PRIMER produced by Jiangsu Derwei Paint Co., Ltd.

[0244] The intermediate paint is DWB AC PRIMER produced by Jiangsu Dewei Paint Co., Ltd. The polyurethane topcoat is DWpu FINISH 20 produced by Jiangsu Dewei Paint Co., Ltd.

[0245] Test method and results:

[0246] The samples produced by the construction processes of the embodiment and the comparative example were subjected to corrosion expansion performance tests: the specific test method is:

[0247] Cold-rolled steel plates of the same material, thickness and size were used, and the construction processes in Example 1, Example 2, Example 3 and the comparative example were used to produce Sample 1, Sample 2, Sample 3 and Sample 4, respectively.

[0248] Cold-rolled steel plates of the same material, thickness and size were used, and the protective coatings of Examples 4 to 15 and the protective coatings of Comparative Examples 2 to 5 were respectively used to make samples using the construction process in this application under the same conditions.

[0249] The same T-shaped lines are made on sample 1, sample 2, sample 3 and sample 4. The specific method of making the T-shaped lines is as follows:

[0250] Draw a T-shaped line on the template, and use a blade to draw a line to the bottom. The lengths of the T-shaped line are 50mm and 76mm respectively.

[0251] The same T-shaped lines were made on the samples of Examples 4 to 15 and Comparative Examples 2 to 5. The specific method of making the T-shaped lines is as follows:

[0252] Draw a T-shaped line on the template, and use a blade to draw a line to the bottom. The lengths of the T-shaped line are 50mm and 76mm respectively.

[0253] Samples 1, 2, 3, and 4 were placed in the same salt spray test chamber and removed after 1000 hours. The chamber contained a 5% sodium chloride solution, a temperature of (35±2)°C, and a pH of 6.5 to 7.2 (at 25°C).

[0254] The samples of Examples 4 to 15 and Comparative Examples 2 to 5 were placed in the same salt spray test chamber and removed after 1000 hours. The test chamber contained a settling salt solution having a concentration of 5% sodium chloride solution, a chamber temperature of (35±2)°C, and a pH value of 6.5 to 7.2 (at 25°C).

[0255] The results are shown in Figures 1-4. After measurement, the corrosion expansion performance test results are shown in Table 1, where the corrosion width is the average width.

[0256] Table 1

[0257] The test results show that the corrosion resistance of the present invention significantly outperforms that of existing technologies. The corrosion width of Sample 4 is over 1.8 times that of Sample 3. Furthermore, the corrosion performance of Sample 4 is significantly higher than that of the present invention, judging from the overall corrosion effect of the samples. This means that not only is the thickness of the present invention significantly lower than that of the spray coating used in the prior art, but its corrosion resistance is also significantly superior to that of the prior art. In particular, its corrosion resistance significantly outperforms that of the prior art.

[0258] The corrosion widths of Examples 4 to 15 are significantly smaller than those of Comparative Examples 2 to 5. Therefore, the corrosion resistance of Examples 4 to 15 is significantly better than that of the prior art.

[0259] Combining Figures 5-7 and 11, it is clearly observed that the corrosion in Comparative Example 2 is more severe. Combining Figures 8-10 and 12, it is clearly observed that the corrosion in Comparative Example 3 is more severe. Therefore, the use of the zinc-free primer in this application can avoid the effects of zinc-induced accelerated corrosion expansion, ensuring the anti-corrosion performance of the entire protective coating.

[0260] Corrosion resistance is a crucial parameter for shipping containers. Shipping containers are transported at sea, subject to harsh natural conditions. Frequent friction and collisions between containers due to waves can easily cause wear and tear on the containers. Therefore, high corrosion resistance is required. The present invention not only uses less material but also significantly outperforms existing products in corrosion resistance. Furthermore, the construction process of the present invention avoids wastewater discharge and reduces VOC emissions, resulting in excellent environmental protection.

[0261] Although the embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are illustrative and cannot be understood as limitations on the present disclosure. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present disclosure. Therefore, any changes or modifications made in accordance with the claims and description of the present disclosure shall fall within the scope of the patent of the present disclosure.

Claims

1. A powder protective coating for a shipping container, characterized in that: The container includes an inner surface of the container and an outer surface of the container; At least part of the container is made of metal sheet; in: The metal sheet forming the inner surface of the container includes at least three layers of coating structure: A1 layer, A2 layer, and A3 layer. The material of A1 layer includes: high-solid oil-based paint, non-metallic conductive material; A1 layer does not contain metal zinc; the material of A2 layer is epoxy powder; the material of A3 layer is epoxy powder; And / or, the metal sheet forming the outside of the container comprises at least: a three-layer coating structure of B1 layer, B2 layer, and B3 layer; the material of B1 layer comprises: high-solid oil-based paint, non-metallic conductive material; B1 layer does not contain metallic zinc; the material of B2 layer is epoxy powder; the material of B3 layer is polyester powder.

2. The protective coating according to claim 1, characterized in that: The A1 layer is formed by roller coating before the metal sheet is formed into a container; the A2 and A3 layers are formed by spray coating after the container body is formed; And / or, the B1 layer is formed by roller coating before the metal sheet is formed into a container; and the B2 and B3 layers are formed by spray coating after the container body is formed.

3. The protective coating according to claim 1, characterized in that: in, The thickness of the A1 layer is smaller than that of the A2 and A3 layers; And / or, the thickness of the B1 layer is smaller than the thickness of the B2 and B3 layers.

4. The protective coating according to claim 1, characterized in that: The solid content of the high-solid oily paint in the A1 layer is not less than 60%, and the content of the non-metallic conductive material ranges from 0.5% to 10% of the weight of the high-solid oily paint; And / or, the solid content of the high-solid oily paint in the B1 layer is not less than 60%, and the content of the non-metallic conductive material is in the range of 0.5%-10% of the weight of the high-solid oily paint.

5. The protective coating according to claim 1, characterized in that: The thickness of the A1 layer is 8-12 microns, the thickness of the A2 layer is 37-43 microns, and the thickness of the A3 layer is 38-43 microns; And / or, the thickness of the B1 layer is 8-12 microns, the thickness of the B2 layer is 37-43 microns, and the thickness of the B3 layer is 44-46 microns.

6. The protective coating according to claim 1, characterized in that: The non-metallic conductive material in the A1 and B1 layers is graphite, and the content of graphite is approximately 2%.

7. The protective coating according to claim 1, characterized in that: The solid content ratio of the high-solid oily paint in the A1 and B1 layers is 70%, and the content of the non-metallic conductive material is in the range of 5% of the weight of the high-solid oily paint.

8. The protective coating according to claim 1, characterized in that: The materials forming the A1 layer and the B1 layer include, by mass percentage, 25-30% of modified epoxy resin, 10-15% of anti-rust pigment, 3-5% of cyclohexanone, 8-10% of xylene, 3-6% of n-butanol, 8-20% of curing agent, and 0.5-10% of non-metallic conductive material, and the rest are pigments and fillers.

9. The protective coating according to claim 8, characterized in that The non-metallic conductive material includes at least one of graphite, graphene and conductive mica.

10. The protective coating according to claim 1, characterized in that According to mass percentage, the epoxy powders of A2 and B2 include: 25-50% polyester resin, 22-45% epoxy resin, 1-10% phenolic curing agent, 0.1-2.4% accelerator, 0.5-2% leveling agent, 0.1-2% deaerator, 5-30% composite filler and 0.2-2% toughening agent, and the rest are pigments and fillers.

11. The protective coating according to claim 10, characterized in that The polyester resin has an acid value of 34 to 76 mgKOH / g and a viscosity of 3000 to 6000 mPa.s; and / or, The epoxy value of the epoxy resin is 0.090-0.165 eq / 100 g, and the softening point is 87-105° C.

12. The protective coating according to claim 1, characterized in that According to mass percentage, the epoxy powder A3 includes 30-60% polyester resin, 20-36% epoxy resin, 0.5-1% leveling agent, 0.1-1% defoaming agent, 0.2-2% antioxidant and 0.5-3% toughening agent, and the rest is pigment and filler.

13. The protective coating according to claim 12, characterized in that The polyester resin has an acid value of 34 to 76 mgKOH / g and a viscosity of 3000 to 6000 mPa.s; and / or, The epoxy value of the epoxy resin is 0.090-0.165 eq / 100 g, and the softening point is 87-105° C.

14. The protective coating according to claim 1, characterized in that According to mass percentage, the B3 polyester powder includes 30-45% of high weather-resistant polyester resin, 22-35% of super weather-resistant polyester resin, 0-3.5% of triglycidyl isocyanurate, 0-2.5% of hydroxyalkylamide, 14-24% of blocked polyisocyanate, 0.5-1.5% of leveling agent, 0.1-3% of accelerator, 0.1-1% of defoamer, 0.5-3.2% of toughening agent, 0.2-2% of antioxidant and 2-25% of composite filler, and the rest is color filler.

15. The protective coating according to claim 14, characterized in that The acid value of the highly weather-resistant polyester is 29-34 mgKOH / g, and the viscosity is 4500-6000 mPa﹒ s; The super weather-resistant polyester has a hydroxyl value of 100-120 mgKOH / g and a viscosity of 3200-4200 mPa﹒s.

16. A construction process for a protective coating of a container according to any one of claims 1 to 15, characterized in that: The steps include: Derusting and / or sanding metal sheets; With hot coating, the coating or the plate is heated before coating the A1 layer and the B1 layer; Drying or air drying, wherein the air drying uses hot air; Processing and welding metal sheets to form a box; Sandblast the welds of the entire box; A2 layer and B2 layer are sprayed; A3 layer and B3 layer are sprayed; Solidify and cool.

17. The construction process according to claim 16, characterized in that: When hot air is used for air drying, the temperature of plates thicker than 4 mm after hot air heating shall not be lower than 85°C.

18. A shipping container, characterized in that: The protective coating comprises any one of claims 1 to 15; or, the construction process comprises any one of claims 16 to 17.

19. A zinc-free primer for a container, characterized in that: According to the mass percentage, it includes: 25-30% of modified epoxy resin, 10-15% of anti-rust pigment, 3-5% of cyclohexanone, 8-10% of xylene, 3-6% of n-butanol, 8-20% of curing agent, and 0.5-10% of non-metallic conductive material, and the rest is color filler.

20. The zinc-free primer according to claim 19, characterized in that The non-metallic conductive material includes at least one of graphite, graphene and conductive mica.

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