Small-smoke environment-friendly steel drum interior coating and preparation method thereof
By using components such as oxidized polyethylene wax, silane coupling agent and nylon wax, a powder coating with uniform particle size was prepared, which solved the problems of poor wettability and smoke in the steel drum, and achieved environmentally friendly construction and high-performance coating.
Patent Information
- Application Number
- CN202510944277.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-09
- Publication Date
- 2025-10-31
AI Technical Summary
Existing water-based coatings for steel drums suffer from poor pigment wetting, easy agglomeration, uneven coating performance, potential smoke generation during baking, and VOC emissions due to the use of traditional solvents, thus affecting environmental performance.
Using amorphous or low-crystallinity oxidized polyethylene wax, silane coupling agent and nylon wax as components, a powder coating with uniform particle size is prepared by melting, crushing and sieving through a twin-screw extruder, avoiding the use of solvents and reducing VOC emissions during coating application.
It improves the scratch resistance, abrasion resistance and anti-blocking properties of the coating, reduces VOC emissions during construction, forms a dense film, and enhances the hardness and gloss of the coating, thus meeting environmental protection requirements.
Abstract
Description
Technical Field
[0001] This invention relates to the field of coating technology for steel drum interiors, specifically to a low-smoke, environmentally friendly coating for steel drum interiors and its preparation method. Background Technology
[0002] Like other water-based coatings, water-based coatings in steel drums suffer from poor pigment wetting and pigment particle agglomeration due to the high surface tension of water, affecting dispersion and film performance. The following is a detailed analysis: Poor Wetting: The surface tension of water in water-based coatings is as high as 72 mN / m, while the surface tension of common substrates is relatively low. This makes it difficult for water-based coatings to fully wet and spread on the substrate, forming a uniform and continuous paint film. The high surface tension of water-based coatings makes pigment particles prone to agglomeration, forming larger particles that affect the uniformity and performance of the coating film.
[0003] Relatively low molecular weight polyethylene wax can serve as an inexpensive, non-polar, low-melting-point polymer solvent to replace traditional volatile alkane solvents, reducing the use of volatile organic solvents and significantly lowering VOC emissions, thus reducing environmental pollution. While PE wax can improve the abrasion resistance and scratch resistance of coatings, excessive PE wax may lead to a decrease in the hardness of the coating film, affecting the abrasion resistance of the coating inside steel drums.
[0004] Even environmentally friendly coatings may produce a small amount of smoke during the baking process. This is mainly because certain components in the coating release small-molecule volatiles at high temperatures. For example, additives in powder coatings (such as leveling agents, matting agents, and wax powders) may produce smoke at high temperatures. Additionally, surface treatment agents for pigments and fillers may decompose at high temperatures, forming smoke. Water-based steel drum coatings, due to their low VOC (volatile organic compound) content, typically do not produce significant smoke during application and baking. Water-based coatings use water as a diluent and do not contain harmful solvents such as benzene, making them more environmentally friendly and producing no noticeable smoke during use. However, in some cases, to adjust coating performance (such as leveling, drying speed, and application properties), a small amount of organic solvent may be added, which will also generate volatile organic compounds (VOCs) during application. Summary of the Invention
[0005] As described in the prior art above, one of the objectives of this invention is to provide a low-smoke, environmentally friendly coating for steel drums. This low-smoke, environmentally friendly coating can be directly applied after melting. Since it does not contain solvents, the coating can reduce the emission of volatile organic compounds (VOCs) during the application process, thus meeting environmental protection requirements.
[0006] The second objective of this invention is to provide a method for manufacturing the smoke-reducing and environmentally friendly coating for steel drums. This method is simple and can be industrially produced.
[0007] One of the objectives of this invention is achieved through the following technical solution: A type of environmentally friendly coating for steel drums with low smoke emission comprises the following raw materials by weight: 15-20 parts resin, 5-8 parts amorphous or low-crystallinity oxidized polyethylene wax, 8-10 parts silane coupling agent, 5-8 parts nylon wax, 6-8 parts nanomaterials, 5-8 parts pigment, 3-5 parts filler, 5-6 parts additives, and 5-6 parts curing agent.
[0008] Further, the raw materials, by weight, include: 15 parts resin, 8 parts amorphous or low-crystallinity oxidized polyethylene wax, 10 parts silane coupling agent, 8 parts nylon wax, 7 parts pigment, 7 parts nanomaterials, 4 parts filler, 5 parts additives, and 5 parts curing agent.
[0009] Furthermore, the particle size of the amorphous or low-crystallinity oxidized polyethylene wax is 3-20 μm.
[0010] Furthermore, the additives include leveling agents, matting agents, antioxidants, lubricants, and anti-caking agents.
[0011] Furthermore, the resin is epoxy resin, phenolic resin, epoxy phenolic resin, polyvinyl fluoride, polyester resin, or acrylic resin.
[0012] Furthermore, the nanomaterial is one of nano-silica or nano-alumina.
[0013] The second objective of this invention is achieved by the following technical solution: A method for manufacturing a low-smoke, environmentally friendly coating for the inside of a steel drum includes the following steps: S1. Weigh each component of the environmentally friendly steel drum coating according to the formula. First, mix the polyethylene wax and the nylon wax and add them to a twin-screw extruder. Set the melting temperature to 180℃-220℃ and the melting time to 10-20 minutes to ensure that the polyethylene wax and the nylon wax are completely melted. Then mix them with the other components of the environmentally friendly steel drum coating to obtain a mixture. S2. The mixture is extruded using a twin-screw extruder to obtain an extrudate. During pulverization, the extrudate is first cooled to about -140°C with liquid nitrogen to make it brittle, and then mechanically pulverized. After pulverization, a fine sieve is used to screen out powder coatings that meet the particle size requirements, with the particle size controlled between 10-50 micrometers. S3. Screening and Grading: Further screening is carried out using sieves of different mesh sizes to remove coarse particles and impurities, resulting in powder coatings with uniform particle size.
[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The environmentally friendly steel drum coating provided by this invention, which reduces smoke, utilizes oxidized polyethylene wax to improve the scratch resistance, abrasion resistance, and anti-blocking properties of the coating. These properties are crucial for preventing damage to the inner coating of the steel drum during transportation and use. The oxidized polyethylene wax molecular chain contains polar groups such as carbonyl and hydroxyl groups, making it more polar than polyethylene wax and significantly improving its compatibility with epoxy-phenolic resins. Furthermore, in epoxy resin coatings, oxidized polyethylene wax can improve the wetting and dispersibility of pigments, reduce pigment agglomeration in the epoxy resin coating, and enhance the coloring effect and performance of the coating.
[0015] The addition of nylon wax and oxidized polyethylene wax provides flexibility. Oxidized polyethylene wax has a lower glass transition temperature, while nylon wax has a higher glass transition temperature. By blending them in an appropriate ratio, the overall Tg of the coating can be increased, enhancing its hardness. This blending method effectively improves the overall performance of the coating, achieving a balance between hardness and flexibility. It further enhances the abrasion resistance and scratch resistance of the coating film.
[0016] Silane coupling agents contain two functional groups with different properties in their molecular structure. The siloxane group (e.g., Si-O-Si) can react with hydroxyl groups on the surface of inorganic materials (such as pigments, fillers, and substrates) to form strong chemical bonds; while the organic functional group at the other end (e.g., epoxy, amino, methacryloyloxy) can react with organic materials (such as resins), thus forming a chemical bridge between inorganic and organic materials. In epoxy-phenolic coatings, the organic functional group of the silane coupling agent can react with the polar groups in the epoxy-phenolic resin to form strong chemical bonds. Simultaneously, the siloxane group of the silane coupling agent can react with trace amounts of polar carbonyl and hydroxyl groups on the surface of oxidized polyethylene wax, forming chemical bonds between the oxidized polyethylene wax and the epoxy-phenolic resin, thus allowing the oxidized polyethylene wax to be better dispersed in the epoxy-phenolic resin.
[0017] The present invention provides a low-smoke, environmentally friendly steel drum coating. The coating contains oxidized polyethylene wax, replacing the organic solvents in existing epoxy-phenolic coatings and the water in existing epoxy-phenolic water-based coatings. During use, the coating can be directly applied by simply setting the melting temperature of the low-smoke, environmentally friendly steel drum coating to 180℃-220℃ and the melting time to 10-20 minutes. Since it does not contain solvents, the coating can reduce the emission of volatile organic compounds (VOCs) during the application process, thus meeting environmental protection requirements.
[0018] The environmentally friendly steel drum coating provided by this invention, during the drying and curing process, utilizes the fluidity of oxidized polyethylene wax to allow for more uniform distribution of nanomaterials, forming a dense structure. This further enhances the hardness and abrasion resistance of the coating film and reduces VOC emissions. The nanomaterials can fill the micropores in the coating, creating a denser structure and improving the overall performance of the coating. During application, the good fluidity allows the coating to spread and cover the substrate surface better, while improving the smoothness and gloss of the coating and reducing defects such as uneven coating and orange peel. This good fluidity also allows the coating to interact with other components such as resins, pigments, and fillers to form a homogeneous mixture, preventing component separation or sedimentation and ensuring the stability and consistent performance of the product during use. Detailed Implementation
[0019] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the embodiments or technical features described below can be arbitrarily combined to form new embodiments.
[0020] Example 1
[0021] This embodiment provides a low-smoke, environmentally friendly coating for steel drums. The raw materials, by weight, include: 15 parts epoxy resin, 8 parts amorphous or low-crystallinity oxidized polyethylene wax, 10 parts silane coupling agent, 8 parts nylon wax, 7 parts pigment, 7 parts nanomaterial nano silica, 4 parts filler, 5 parts additives, and 5 parts curing agent.
[0022] In this embodiment, the additives include leveling agents, matting agents, antioxidants, lubricants, and anti-caking agents.
[0023] In this embodiment, the particle size of the amorphous or low-crystallinity oxidized polyethylene wax is 3 μm.
[0024] This embodiment also provides a method for preparing a low-smoke, environmentally friendly coating for the inside of a steel drum, including the following steps: S1. Weigh each component of the coating for the steel drum of the smoke-reducing environmental protection product according to the formula. First, mix the polyethylene wax and nylon wax and add them to the twin-screw extruder. Set the melting temperature to 180℃ and the melting time to 15 minutes to ensure that the polyethylene wax and nylon wax are completely melted. Then mix them with the other components of the coating for the steel drum of the smoke-reducing environmental protection product to obtain a mixture. S2. The extruder extrudes the mixture to obtain the extrudate. During the crushing process, the extrudate is first cooled to about -140°C with liquid nitrogen to make it brittle, and then mechanically crushed. After crushing, a fine sieve is used to screen out the powder coating that meets the particle size requirements, and the particle size is controlled within 10 micrometers. S3. Screening and Grading: Further screening is carried out using sieves of different mesh sizes to remove coarse particles and impurities, resulting in powder coatings with uniform particle size.
[0025] This embodiment uses oxidized polyethylene wax. The oxidized polyethylene wax molecular chain has polar groups, which can interact with the resin to a certain extent, increasing the rigidity of the wax molecules and thus improving the hardness of the coating film. A polyethylene wax with low crystallinity is selected because the wax molecules with low crystallinity are relatively disordered, having less impact on the uniformity of the coating film and contributing to improved coating film hardness.
[0026] Silane coupling agents Mechanism of action: Silane coupling agents contain two different groups in their molecular structure: one group (such as epoxy groups and amino groups) that can react with the surface of inorganic materials (such as pigments and fillers), and another group (such as methoxy groups and ethoxy groups) that can react with organic materials (such as resins and waxes). Through the interaction of these two groups, silane coupling agents can form a chemical bridge between inorganic and organic materials, thereby improving their compatibility.
[0027] Improved compatibility: In coating systems, silane coupling agents can interact simultaneously with polyethylene wax and resin, allowing the polyethylene wax to be better dispersed in the resin and forming a homogeneous system. For example, adding a silane coupling agent to epoxy-phenolic coatings can improve the compatibility between polyethylene wax and epoxy-phenolic resin, reduce phase separation, and improve the overall performance of the coating film.
[0028] Example 2
[0029] This embodiment provides a low-smoke, environmentally friendly coating for steel drums. The raw materials, by weight, include: 18 parts phenolic resin, 5 parts amorphous or low-crystallinity oxidized polyethylene wax, 9 parts silane coupling agent, 5 parts nylon wax, 6 parts nanomaterial nano-alumina, 8 parts pigment, 5 parts filler, 6 parts additives, and 6 parts curing agent.
[0030] In this embodiment, the additives include leveling agents, matting agents, antioxidants, lubricants, and anti-caking agents.
[0031] In this embodiment, the particle size of the amorphous or low-crystallinity oxidized polyethylene wax is 10 μm.
[0032] This embodiment also provides a method for preparing a low-smoke, environmentally friendly coating for the inside of a steel drum, including the following steps: S1. Weigh each component of the coating for the steel drum of the smoke-reducing environmental protection product according to the formula. First, mix the polyethylene wax and nylon wax and add them to the twin-screw extruder. Set the melting temperature to 185℃ and the melting time to 10 minutes to ensure that the polyethylene wax and nylon wax are completely melted. Then mix them with the other components of the coating for the steel drum of the smoke-reducing environmental protection product to obtain a mixture. S2. The extruder extrudes the mixture to obtain the extrudate. During the crushing process, the extrudate is first cooled to about -140°C with liquid nitrogen to make it brittle, and then mechanically crushed. After crushing, a fine sieve is used to screen out the powder coating that meets the particle size requirements, and the particle size is controlled within 50 micrometers. S3. Screening and Grading: Further screening is carried out using sieves of different mesh sizes to remove coarse particles and impurities, resulting in powder coatings with uniform particle size.
[0033] Oxidation reaction of polyethylene wax: An oxidizing agent is added to polyethylene wax, and an oxidation reaction is carried out under certain temperature and pressure. Commonly used oxidizing agents include air, oxygen, and peroxides. The oxidation reaction causes some carbon atoms in the polyethylene wax molecular chain to be oxidized into polar groups such as carbonyl groups, thereby disrupting the regularity of the molecular chain and reducing crystallinity.
[0034] Controlling the degree of oxidation: The crystallinity of oxidized polyethylene wax can be adjusted by controlling the conditions of the oxidation reaction, such as temperature, pressure, and reaction time. For example, a lower reaction temperature and a shorter reaction time can yield oxidized polyethylene wax with a lower degree of crystallinity.
[0035] Post-processing: The product after the oxidation reaction needs to undergo further processing, such as filtration, washing, and drying, to remove unreacted oxidizing agents and byproducts, and obtain pure oxidized polyethylene wax. The particle size of polyethylene wax has a significant impact on coating performance. Generally, a particle size of 3-20 μm is suitable. If the particle size is too small, it may affect the matting effect and make it difficult to form an effective protective layer on the coating surface; if the particle size is too large, it will lead to an increase in the surface roughness of the coating, affecting the gloss and smoothness of the coating, and may also reduce the hardness.
[0036] Example 3
[0037] This embodiment provides a low-smoke, environmentally friendly coating for steel drums, comprising the following raw materials by weight: 20 parts polyvinyl fluoride, 6 parts amorphous or low-crystallinity oxidized polyethylene wax, 8 parts silane coupling agent, 6 parts nylon wax, 5 parts pigment, 8 parts nano silica, 3 parts filler, 5.5 parts additives, and 5.5 parts curing agent.
[0038] In this embodiment, the additives include leveling agents, matting agents, antioxidants, lubricants, and anti-caking agents.
[0039] In this embodiment, the particle size of the amorphous or low-crystallinity oxidized polyethylene wax is 20 μm.
[0040] This embodiment also provides a method for preparing a low-smoke, environmentally friendly coating for the inside of a steel drum, including the following steps: S1. Weigh each component of the coating for the steel drum of the smoke-reducing environmental protection product according to the formula. First, mix the polyethylene wax and nylon wax and add them to the twin-screw extruder. Set the melting temperature to 220℃ and the melting time to 20 minutes to ensure that the polyethylene wax and nylon wax are completely melted. Then mix them with the other components of the coating for the steel drum of the smoke-reducing environmental protection product to obtain a mixture. S2. The extruder extrudes the mixture to obtain the extrudate. During the crushing process, the extrudate is first cooled to about -140°C with liquid nitrogen to make it brittle, and then mechanically crushed. After crushing, a fine sieve is used to screen out the powder coating that meets the particle size requirements, and the particle size is controlled within 35 micrometers. S3. Screening and Grading: Further screening is carried out using sieves of different mesh sizes to remove coarse particles and impurities, resulting in powder coatings with uniform particle size.
[0041] Example 4
[0042] This embodiment provides a low-smoke, environmentally friendly coating for steel drums. The raw materials, by weight, include: 15 parts polyester resin, 8 parts amorphous or low-crystallinity oxidized polyethylene wax, 10 parts silane coupling agent, 8 parts nylon wax, 7 parts pigment, 3 parts nano silica, 4 parts nano alumina, 4 parts filler, 5 parts additives, and 5 parts curing agent.
[0043] In this embodiment, the additives include leveling agents, matting agents, antioxidants, lubricants, and anti-caking agents.
[0044] In this embodiment, the particle size of the amorphous or low-crystallinity oxidized polyethylene wax is 3 μm.
[0045] Example 5
[0046] This embodiment provides a low-smoke, environmentally friendly coating for steel drums. The raw materials, by weight, include: 15 parts acrylic resin, 8 parts amorphous or low-crystallinity oxidized polyethylene wax, 10 parts silane coupling agent, 8 parts nylon wax, 7 parts pigment, 3 parts nano silica, 4 parts nano alumina, 4 parts filler, 5 parts additives, and 5 parts curing agent.
[0047] In this embodiment, the additives include leveling agents, matting agents, antioxidants, lubricants, and anti-caking agents.
[0048] In this embodiment, the particle size of the amorphous or low-crystallinity oxidized polyethylene wax is 3 μm.
[0049] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.
Claims
1. A low-smoke, environmentally friendly coating for the inside of steel drums, characterized in that: The raw materials, by weight, include: 15-20 parts resin, 5-8 parts amorphous or low-crystallinity oxidized polyethylene wax, 8-10 parts silane coupling agent, 5-8 parts nylon wax, 6-8 parts nanomaterials, 5-8 parts pigment, 3-5 parts filler, 5-6 parts additives, and 5-6 parts curing agent.
2. The low-smoke, environmentally friendly coating for steel drums as described in claim 1, characterized in that, The raw materials, by weight, include: 15 parts resin, 8 parts amorphous or low-crystallinity oxidized polyethylene wax, 10 parts silane coupling agent, 8 parts nylon wax, 7 parts pigment, 7 parts nanomaterials, 4 parts filler, 5 parts additives, and 5 parts curing agent.
3. The low-smoke, environmentally friendly coating for steel drums as described in claim 1, characterized in that, The particle size of the amorphous or low-crystallinity oxidized polyethylene wax is 3-20 μm.
4. The low-smoke, environmentally friendly coating for steel drums as described in claim 1, characterized in that, The additives include leveling agents, matting agents, antioxidants, lubricants, and anti-caking agents.
5. The low-smoke, environmentally friendly coating for steel drums as described in claim 1, characterized in that, The resin is epoxy resin, phenolic resin, epoxy phenolic resin, polyvinyl fluoride, polyester resin, or acrylic resin.
6. The low-smoke, environmentally friendly coating for steel drums as described in claim 1, characterized in that, The nanomaterial is either nano-silica or nano-alumina.
7. The method for preparing the smoke-reducing and environmentally friendly coating for the inside of a steel drum according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Weigh each component of the environmentally friendly steel drum coating according to the formula. First, mix the polyethylene wax and the nylon wax and add them to a twin-screw extruder. Set the melting temperature to 180℃-220℃ and the melting time to 10-20 minutes to ensure that the polyethylene wax and the nylon wax are completely melted. Then mix them with the other components of the environmentally friendly steel drum coating to obtain a mixture. S2. The mixture is extruded using a twin-screw extruder to obtain an extrudate. During pulverization, the extrudate is first cooled to about -140°C with liquid nitrogen to make it brittle, and then mechanically pulverized. After pulverization, a fine sieve is used to screen out powder coatings that meet the particle size requirements, with the particle size controlled between 10-50 micrometers. S3. Screening and Grading: Further screening is carried out using sieves of different mesh sizes to remove coarse particles and impurities, resulting in powder coatings with uniform particle size.