CN117046701A - Sea container, powder protective coating for sea container and construction process of powder protective coating - Google Patents

Abstract

The invention relates to a shipping container, a shipping container powder protective coating and a construction process thereof, and develops zinc-free pretreatment primer. Adopts high-solid oil-containing paint and non-metallic conductive material to replace metallic zinc. Compared with the prior art, the method has the advantages that the method does not contain metallic zinc, so that the phenomenon of corrosion expansion can be reduced. Because the nonmetallic electroconductive material and the high-solid oily paint are mixed more fully, the first layer can be thinner, and meanwhile, the corrosion resistance is better. Meanwhile, the adhesive force of the powder is better, and the subsequent spraying is more facilitated. In order to avoid the problem of sewage discharge after degreasing pretreatment such as acid and alkali, the construction process adopts a laser fine sanding treatment mode for pretreatment, so that dust discharge and noise generation can be reduced.

Description

A kind of shipping container, shipping container powder protective coating and construction technology thereof

Technical field

The present invention relates to the field of material technology, and in particular to a shipping container, a shipping container powder protective coating and a construction process thereof.

Background technique

Traditional water-based paint coating for container protection consumes a large amount of organic solvents and produces a large amount of waste water and waste residue. Pollution problems have always plagued the industry.

In the field of containers, Jingyuan has successfully developed powder coatings for containers in 2022. After the official announcement in August 2022, it produced nearly 30,000 TEU containers and formed a group standard. Currently, the applicant uses a protective coating system for container cold-rolled steel plates, in which the first layer is a zinc-rich primer with a thickness of more than 35 microns, followed by spraying of a base coat and a top coat.

Specifically, when using metal plates, such as cold-rolled steel plates, to produce containers, there is a small amount of oil on the surface of the cold-rolled steel plates when they leave the factory due to process reasons. Therefore, pre-treatment must be carried out before the cold-rolled steel plates are cold-worked. First, the surface of the steel plates should be degreased (acid or alkali solution After degreasing), clean, dry (air dry or hot air), perform shot blasting, and pre-coat with zinc-rich primer. After the pre-treatment is completed, the cold work process (punching, shearing and forming) is carried out, the steel structure is assembled and welded, and the weld seam is shot blasted before the whole box painting operation (including spray painting, powder spraying, etc.).

In specific use, the performance of the containers produced by the above-mentioned spraying method surpasses the containers produced by the previous water-based paint method. However, the above-mentioned pre-processing process of cold-rolled steel plates has the following problems: 1. There is a problem of sewage treatment; 2. The zinc-rich primer is an oil-based paint (non-water-based) and there is a problem of VOC emissions. Both of the above points bring hidden dangers of substandard environmental protection. At the same time, the applicant found that once corrosion occurs in shipping containers with high corrosion resistance requirements, the corrosion will expand seriously.

After research and analysis, the applicant found that the serious corrosion expansion is due to the zinc salt generated after corrosion of zinc powder, which expands in volume. The single powder coating is extremely dense and cannot accommodate the zinc salt that expands in volume, thus causing the powder coating to separate from the substrate. , the entire powder coating appears to be "peeling"; and as the zinc powder continues to corrode, the "peeling" will continue to extend. At the same time, the applicant found that since the surface coating contains zinc, compared with the zinc-free system, there is a risk of quality degradation when combined with the subsequent powder coating.

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

Contents of the invention

In order to alleviate or solve at least one aspect or at least one point of the above problems, the present invention is proposed.

The present invention provides a powder protective coating for a shipping container. The container includes an inner surface and an outer surface of the container; at least part of the container is made of metal plates;

in:

The metal plate forming the inner surface of the container at least includes: A1 layer, A2 layer, and A3 layer three-layer coating structure: A1 layer materials include: high-solid oil paint, non-metallic conductive materials; A1 layer does not contain metallic zinc; A2 The material of the layer is epoxy powder; the material of A3 layer is epoxy powder;

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

Preferably, the A1 layer does not contain zinc; the B1 layer does not contain zinc.

Preferably, the A1 layer is formed by roller coating before the metal plate is formed into the container; the A2 and A3 layers are formed by spraying after the container body is formed; and/or the B1 layer is formed by roller coating before the metal plate is formed into the container; The B2 and B3 layers are formed by spraying after forming the container body.

Preferably, 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; the thickness of the A1 layer is preferably less than 20 microns, and more preferably less than 12 microns. .

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

Preferably, the solid content of the high solid oil 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 oil paint;

And/or, the solid content of the high-solid oil-based paint in layer B1 is not less than 60%, and the content of non-metallic conductive materials ranges from 0.5% to 10% of the weight of the high-solid oil-based paint.

Preferably, the zinc content in layers A1 and B1 is zero, and the thicknesses of layer A1 and layer B1 are approximately the same.

Preferably, the non-metallic conductive material in the A1 and B1 layers is graphite, and the graphite content is approximately 2%.

Preferably, the solid content ratio of the high-solid oil-based paint in layers A1 and B1 is 70%, and the content range of non-metallic conductive materials is 5% of the weight of the high-solid oil-based paint.

In addition, the present invention also provides a construction process of protective coating for containers, which is characterized in that it includes the following steps:

Perform laser rust removal and sand blasting on metal sheets;

With hot roller coating, the A1 layer and B1 layer are coated after heating the paint or heating the plate;

Air dry, use hot air to dry;

Process and weld metal sheets to form a box;

Sand blast the welds of the entire box;

The A2 layer and B2 layer are sprayed; the A3 layer and B3 layer are sprayed;

Solidify and cool.

Preferably, when hot air is used for air drying, the temperature after hot air heating for thick plates above 4 mm should not be lower than 85°C.

Preferably, before hot roll coating, it also includes a process of uniformly mixing the high-solid oil paint and the non-metallic conductive material.

Preferably, after the metal plate is sandblasted, its surface roughness is between 15-35 microns.

The present invention also provides a shipping container, including any one of the aforementioned protective coatings; or using the aforementioned construction technology.

The present invention further improves and optimizes the powder coating system and develops a zinc-free pre-treatment primer. Use high-solid oil-based paint and use non-metallic conductive materials instead of metallic zinc. Through the above arrangement, compared with the prior art, the phenomenon of corrosion expansion can be reduced because it does not contain metallic zinc.

Since the first layer uses high-solid oil paint and non-metallic conductive materials, non-metallic conductive materials are used instead of metallic zinc. On the one hand, it can ensure the conductive performance and facilitate subsequent spraying. At the same time, the corrosion expansion phenomenon can be reduced. At the same time, because the non-metallic conductive materials and high-solid oil paint are more fully mixed, the first layer can be made thinner, and at the same time, its corrosion resistance is better.

Since it does not contain metal materials, its powder has better adhesion and is more conducive to subsequent spraying. Through actual verification, the zinc-free pre-treatment primer fully meets the requirements for rust prevention between processes. The adhesion between the zinc-free pre-treatment primer and the powder is better, the corrosion expansion is better than that of water-based paint, and the welding performance is consistent with that of zinc-rich primer. At the same time, the cost of zinc-free pre-treatment primer is lower than that of zinc-rich primer, and it is also lighter.

In the construction process of the present invention, the pre-treatment adopts laser rust removal, which avoids the discharge of sewage and uses high-solid paint, which effectively reduces the emission of VOC. Compared with the existing technology, its thickness is greatly reduced, saving money. Material, its environmental protection effect is good.

Description of the drawings

Figure 1 is an experimental sample of anti-corrosion propagation performance in Example 1 of the present invention.

Figure 2 is an experimental sample of anti-corrosion propagation performance in Example 2 of the present invention.

Figure 3 is an experimental sample of anti-corrosion propagation performance in Example 2 of the present invention.

Figure 4 shows experimental samples of anti-corrosion propagation performance in comparative examples.

Detailed ways

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

Features described herein may be implemented in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein have been provided to illustrate only some of the many possible ways of implementing the methods, apparatus, and/or systems described herein that will be apparent upon understanding this disclosure. clearly.

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 referred to as restricted by these terms. Rather, these terms are only used to distinguish one member, component, region, layer or section from another member, component, region, layer or section.

In the specification, when an element (such as a layer, region, or substrate) is described as being "on," "connected to" or "coupled to" another element, that element can be directly "on" the other element on, directly "connected to" or "coupled to" another element, or there may be one or more other intervening elements present. In contrast, when an element is described as being "directly on," "directly connected to" or "directly coupled to" another element, there may be no intervening elements present.

The terms used herein are used only to describe various examples and are not intended to limit the disclosure. The singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "includes," and "having" indicate the presence of recited features, quantities, operations, components, elements and/or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components , components and/or combinations thereof.

In order to enable those skilled in the art to use the content of the present invention, the following exemplary embodiments may be given below in combination with specific application scenarios, specific systems, parameters of devices and components, and specific connection methods. However, for those skilled in the art, these embodiments are only examples, and the general principles defined here can be applied to other embodiments and application scenarios without departing from the spirit and scope of the invention.

Example 1:

Step 1: Remove rust from the metal plate and perform fine sanding to achieve a surface roughness of between 15-35 microns. Laser rust removal is used to remove rust, which can avoid contamination compared with existing rust removal methods. .

Step 2: Roll coating. Use high-solid oil paint to coat the metal plate with the first layer. The thickness of the first layer of coating is 10 microns. Among them, the solid content of the high-solid oil paint is more than 60%. Add 2% graphite and mix it thoroughly; it can be applied with hot roller coating, and the temperature of hot roller coating is above 40 degrees.

Step 3: Air-dry the coated metal sheet;

Step 4: Process the dried metal sheet into a box;

Step 5: Perform the whole box welding seam deoxidation layer treatment on the box;

Step 6: Spray two layers of powder, first spray the base powder, and then spray the flour; 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 epoxy powder Polyester powder, the flour in the box is 40 microns, which is epoxy powder;

Step 7: Solidify and cool.

The container metal plate of the present invention can be a cold-rolled steel plate or a hot-rolled steel plate. The protective coating system includes three layers. In the first layer, the base coating is about 10 microns thick, and the thickness of the base layer is reduced by the high-solid oil paint; compared to Compared with the existing 35 micron base coating, it greatly reduces the use of oil-based paint and can significantly reduce VOC emissions.

Optionally, the solid content ratio of the high-solid oil paint of the present invention is not less than 60%. The present invention adopts a solid content ratio of not less than 60%. Compared with the existing solid content ratio of about 40%, it can be greatly improved. Reduce VOC emissions.

The zinc content of the present invention is zero; non-metal conductive materials are used to replace the original zinc. On the one hand, the conductivity of non-metals is utilized, and on the other hand, the non-metal conductive materials themselves cause less pollution. The non-metal conductive materials can be graphite, etc. If graphite is used to replace the original zinc material, on the one hand it can ensure conductivity and on the other hand it can improve corrosion resistance. Optional in the present invention, the proportion of non-metallic conductive materials is between 0.5% and 10%, and the surface resistance of the base coating is 10 ² ohms to 10 ⁹ ohms. In this example, the solid content ratio is 70%, and the proportion of non-metallic conductive materials is 5%.

The second layer, about 40 microns thick, is epoxy powder. Made of materials that meet FDA requirements. Since the thickness of the first layer is significantly smaller than the existing thickness of the first layer, in order to ensure the quality after coating, the present invention appropriately increases the thickness of the second layer, and its thickness is set to 40 microns;

The third layer is about 45 microns thick outside the box and is made of polyester powder; the inside of the box is about 40 microns thick and is epoxy powder; it meets FDA requirements; the present invention appropriately increases the spray thickness outside the box, thereby further ensuring its coating Anti-corrosion effect after coating.

The powder coating of the present invention not only has excellent environmental performance, but also has all-round advantages over traditional coating processes in terms of process stability and coating quality.

Example 2:

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

Example 3:

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

Comparative ratio:

First, degrease the surface of the metal sheet, then clean, dry, shot blast, and pre-coat with a 35-micron zinc-rich primer. After the pre-treatment is completed, cold work processing (punching, shearing and forming) is carried out, the steel structure is assembled and welded, and the weld seams are shot blasted before the whole box painting operation is carried out; the second layer is sprayed with 35 micron intermediate paint, and the third layer is sprayed with 40 Micron topcoat.

Test methods and results:

The samples produced by the construction techniques of Examples 1, 2, 3 and Comparative Examples were tested for corrosion expansion performance: the specific test method is:

Cold-rolled steel plates of the same material, thickness, and size were used, and the construction techniques in Example 1, Example 2, Example 3, and Comparative Example were used to produce Sample 1, Sample 2, Sample 3, and Sample 4.

Make the same T-shaped lines on sample 1, sample 2, sample 3, and sample 4. The specific production method of T-shaped line is:

Draw a T-shaped line on the sample board and use a blade to draw the bottom line. The lengths of the T-shaped lines are 50mm and 76mm respectively.

Put sample 1, sample 2, sample 3, and sample 4 into the same salt spray test box at the same time, and take them out after 1000 hours. Among them, in the experimental box: the concentration of the sedimentation salt solution: a sodium chloride solution with a mass fraction of 5%, the temperature of the test box: (35±2)°C, and the pH value of the sedimentation salt solution: 6.5~7.2 (25°C).

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

Table 1 Corrosion expansion performance test results of each sample

name Corrosion expansion performance test results Sample 1 Corrosion width 1.64mm Sample 2 Corrosion width 1.70mm Sample 3 Corrosion width 1.60mm Sample 4 Corrosion width 2.92mm

It can be seen from the test results that the anti-corrosion expansion performance of the present invention is significantly better than the anti-corrosion expansion performance of related technologies. Among them, the corrosion width of sample 4 is more than 1.8 times that of sample 3. And judging from the overall corrosion effect of the sample, the corrosion situation of sample 4 is significantly higher than that of the present invention. That is to say, the thickness of the present invention is significantly lower than that of spray coating in the prior art, and its corrosion resistance is significantly better than that of the prior art. And especially its anti-corrosion expansion performance is significantly better than the existing technology.

The corrosion resistance is a very important parameter in shipping containers. Since shipping containers are transported in the sea, their natural conditions are harsh. Due to waves, the containers often cause friction and collision with each other, which can easily cause The container is partially worn, so it has extremely high requirements on corrosion resistance. However, the present invention not only uses less materials, but also has significantly better corrosion resistance than existing products. Moreover, the construction technology of the present invention avoids the discharge of sewage, reduces the discharge of VOC, and has good environmental protection effect.

Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art will understand that changes and combinations of elements can be made to these embodiments without departing from the principles and spirit of the invention. The scope is defined by the appended claims and their equivalents.

Claims (10)

1. A powder protective coating for a shipping container, characterized by: the container comprises an inner container face and an outer container face;

at least part of the container is processed by sheet metal;

wherein:

the metal plate forming the inner surface of the container at least comprises: three-layer coating structures of A1 layer, A2 layer and A3 layer: the materials of the A1 layer include: high-solid oil-based paint and nonmetallic conductive materials; 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;

and/or, the metal sheet forming the outside of the container comprises at least: a B1 layer, a B2 layer and a B3 layer coating structure; the materials of the B1 layer include: high-solid oil-based paint and nonmetallic conductive materials; the layer B1 does not contain metallic zinc; the material of the B2 layer is epoxy powder; the material of the B3 layer is polyester powder.

2. The protective coating of claim 1, wherein: wherein the A1 layer is formed by roll coating before the metal plate is not formed into the container; the layers A2 and A3 are formed by spraying after forming the container body;

and/or, the layer B1 is formed by roll coating before the metal plate is formed into the container; the layers B2 and B3 are formed by spraying after forming the container body.

3. The protective coating of claim 1, wherein: wherein the thickness of the A1 layer is smaller than the thickness of the A2 layer and the A3 layer;

and/or the thickness of the B1 layer is smaller than that of the B2 and B3 layers.

4. The protective coating of claim 1, wherein: the solid content ratio of the high-solid oil-containing paint in the A1 layer is not less than 60%, and the content range of the nonmetallic conductive material is 0.5% -10% of the weight of the high-solid oil-containing paint;

and/or the solid content ratio of the high-solid oil-containing paint in the B1 layer is not less than 60%, and the content of the nonmetallic conductive material is in the range of 0.5-10% of the weight of the high-solid oil-containing paint.

5. The protective coating of claim 1, wherein: the zinc content in the A1 and B1 layers is zero.

6. The protective coating of claim 1, wherein: the nonmetallic conductive materials in the A1 and B1 layers are graphite, and the content of the graphite is approximately 2%.

7. The protective coating of claim 1, wherein: the solid content ratio of the high-solid oil-containing paint in the layers A1 and B1 is 70%, and the content range of the nonmetallic conductive material is 5% of the weight of the high-solid oil-containing paint.

8. A process for the construction of a protective coating for a container as claimed in any one of claims 1 to 7, characterized in that: the method comprises the following steps:

performing laser rust removal and sanding treatment on the metal plate;

carrying out hot rolling coating, namely heating the coating or heating the plate, and then coating the A1 layer and the B1 layer;

air-drying, namely air-drying by adopting hot air;

processing and welding the metal plate to form a box body;

sanding the welding seam of the whole box;

spraying the A2 layer and the B2 layer; spraying the layer A3 and the layer B3;

solidifying and cooling.

9. The construction process according to claim 8, wherein: when the hot air is adopted for air drying, the temperature of the thick plate with the thickness of more than 4mm after the hot air is heated is not lower than 85 ℃.

10. A shipping container, characterized by: comprising a protective coating according to any one of claims 1 to 7; alternatively, the construction process according to claim 8 is used.