Anti-corrosion powder coating and its preparation method and application

Abstract

The present invention relates to an anti-corrosion powder coating, its preparation method, and application. The anti-corrosion powder coating comprises the following raw materials in parts by weight: 100 parts of an epoxy resin composition; 20-30 parts of a polyethylene composition; 30-50 parts of a long-chain alkyl-modified montmorillonite; and 3-5 parts of a silane coupling agent with a reactive group. The epoxy resin composition comprises an epoxy compound and at least two aliphatic polyamines; and the polyethylene composition comprises a first polyethylene and a second polyethylene of different molecular weights. The powder coating exhibits excellent anti-corrosion properties and is resistant to water, solvents, and weathering.

Description

Technical Field

[0001] The present invention relates to the field of powder coatings, and in particular to an anti-corrosion powder coating and a preparation method and application thereof. Background Art

[0002] Powder coatings are a new type of coating developed in recent decades. They are solvent-free and typically in a solid powder form. They offer advantages such as safety, environmental friendliness, high film strength, and ease of application. In recent years, they have been widely used in the automotive, construction, furniture, and electrical appliance industries.

[0003] Powder coatings can be divided into thermoplastic powder coatings and thermosetting powder coatings based on their raw material types. The raw materials for thermoplastic powder coatings typically include thermoplastic resins, plasticizers, pigments, and additives. While thermoplastic powder coatings typically offer advantages such as uniform coating and a smooth surface, they typically require high application temperatures and suffer from poor coloring, limiting their application. The raw materials for thermosetting powder coatings typically include resins, curing agents, additives, and pigments. While thermosetting powder coatings typically offer superior mechanical properties and adhesion, they are prone to uneven powder application.

[0004] Existing ordinary thermosetting powder coatings can meet the application requirements of automobiles, construction, furniture, electrical appliances and other fields. However, with the expansion of application needs, powder coatings are gradually being used in oil pipelines, ships, storage tanks, construction machinery and other fields. However, these fields usually involve complex application environment scenarios, which put higher requirements on the corrosion resistance of powder coatings. Existing powder coatings can no longer meet the application needs of these fields. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the first object of the present invention is to provide an anti-corrosion powder coating, which has good anti-corrosion performance, water resistance, solvent resistance and good weather resistance.

[0006] The second object of the present invention is to provide a method for preparing the anti-corrosion powder coating, which has the advantages of simple steps and the ability to improve coating performance.

[0007] The third object of the present invention is to provide applications of the anti-corrosion powder coating.

[0008] To achieve the first objective of the present invention, the present invention provides an anti-corrosion powder coating, which comprises the following raw materials in parts by mass: 100 parts of an epoxy resin composition; 20 to 30 parts of a polyethylene composition; 30 to 50 parts of a long-chain alkyl-modified montmorillonite; and 3 to 5 parts of a silane coupling agent with a reactive group; wherein the epoxy resin composition comprises an epoxy compound and at least two aliphatic polyamines; and the polyethylene composition comprises a first polyethylene and a second polyethylene having different molecular weights.

[0009] In some embodiments of the present invention, the epoxy compound is selected from at least one of E12 epoxy resin and E14 epoxy resin.

[0010] In some embodiments of the present invention, the aliphatic polyamine is selected from hexamethylenediamine, octanediamine, and nonanediamine.

[0011] In some embodiments of the present invention, the mass ratio of the epoxy compound to the aliphatic polyamine in the epoxy resin composition is 1:(0.2-0.3).

[0012] In some embodiments of the present invention, in the epoxy resin composition, the mass proportion of any one of the aliphatic polyamines in the total mass of the aliphatic polyamines is not less than 30%.

[0013] In some embodiments of the present invention, the first polyethylene is a linear low-density polyethylene with a number average molecular weight of 60,000 to 80,000.

[0014] In some embodiments of the present invention, the second polyethylene is high-density polyethylene with a number average molecular weight of 300,000 to 400,000.

[0015] In some embodiments of the present invention, the mass ratio of the first polyethylene to the second polyethylene is 1:(1-2).

[0016] In some embodiments of the present invention, the long-chain alkyl modified montmorillonite is selected from at least one of hexadecyl quaternary ammonium salt modified montmorillonite and octadecyl quaternary ammonium salt modified montmorillonite.

[0017] In some embodiments of the present invention, the silane coupling agent with a reactive group is selected from at least one of aminosiloxane and epoxysiloxane.

[0018] In some embodiments of the present invention, the raw materials further include additives, and the mass fraction of the additives is 1 to 10 parts relative to 100 parts by mass of the epoxy resin composition.

[0019] In some embodiments of the present invention, the additive is selected from at least one of a pigment, a wetting agent, a dispersant, and a curing accelerator.

[0020] To achieve the second purpose of the present invention, the present invention provides a method for preparing an anti-corrosion powder coating as described in any of the above schemes, which comprises the following steps: step 1: dispersing a silane coupling agent with a reactive group in a solvent to obtain a dispersion; spraying the dispersion on the long-chain alkyl-modified montmorillonite, stirring evenly, and drying to obtain a filler powder; step 2: melt-mixing the polyethylene composition and the filler powder at a first temperature to obtain a mixture; step 3: cooling, adding an epoxy resin composition to the mixture, melt-mixing at a second temperature to obtain a powder, and cooling to obtain a powder.

[0021] In some embodiments of the present invention, the solvent is at least one of water and ethanol.

[0022] In some embodiments of the present invention, the first temperature is 130-150°C.

[0023] In some embodiments of the present invention, the second temperature is 90-110°C.

[0024] To achieve the second purpose of the present invention, the present invention provides an application of the anti-corrosion powder coating described in any of the above schemes, which includes the following steps: spraying the anti-corrosion powder coating onto the surface of the metal substrate and then baking it.

[0025] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0026] The present invention mixes an epoxy resin composition and a polyethylene composition to prepare a powder coating, wherein the epoxy resin composition belongs to a thermosetting system and the polyethylene composition belongs to a thermoplastic system. The two are mixed to form a coating, which can form a coating dispersed with a thermosetting resin and a thermoplastic resin after heating and curing. The coating can have the advantages of both thermosetting resins and thermoplastic resins, improve the crosslinking density and surface smoothness of the coating, give the coating good water resistance, solvent resistance and weather resistance, and ensure the adhesion of the coating to the substrate; in addition, the powder coating is also added with a long-chain alkyl modified montmorillonite as a filler. The montmorillonite has a flaky structure and good barrier properties, and can be The corrosion resistance of the coating is improved in one step. The montmorillonite is modified by long-chain alkyl groups, which can improve the dispersibility of montmorillonite and polyethylene, and increase the chip spacing of montmorillonite, making the montmorillonite more dispersed, thereby better improving the corrosion resistance. In addition, a silane coupling agent with a reactive group is used to improve the compatibility of montmorillonite with the epoxy resin composition and the adhesion to the substrate. By adding long-chain alkyl-modified montmorillonite and a silane coupling agent with a reactive group to the thermosetting epoxy resin composition and the thermoplastic polyethylene composition, the mixing compatibility between the thermosetting resin and the thermoplastic resin is also promoted, making the two mixed more evenly and improving the uniformity of the coating. DETAILED DESCRIPTION

[0027] An embodiment of the present invention provides an anti-corrosion powder coating, which has good water resistance, solvent resistance and weather resistance, and can be used in environments with corrosion risks, such as scenes with complex climates and harsh environments, such as oil pipelines, ships, storage tanks, engineering machinery and other fields.

[0028] Specifically, the anti-corrosion powder coating comprises the following raw materials in parts by mass: 100 parts of an epoxy resin composition; 20 to 30 parts of a polyethylene composition; 30 to 50 parts of a long-chain alkyl-modified montmorillonite; and 3 to 5 parts of a silane coupling agent with a reactive group. The epoxy resin composition is a thermosetting resin system that can be cured under heating conditions to form a cross-linked thermosetting material, thereby improving the mechanical strength, weather resistance and corrosion resistance of the coating. The polyethylene composition is a thermoplastic resin system that can melt at high temperatures, has fluidity and forms a solid after cooling. The polyethylene composition can improve the smoothness and uniformity of the coating surface and avoid corrosion caused by surface defects of the coating. In addition, the polyethylene itself is a non-polar molecular chain with good water resistance, solvent resistance and other properties. Long-chain alkyl-modified montmorillonite is used as a filler. The flaky structure of montmorillonite can be used to improve the barrier properties of the coating and further improve the corrosion resistance of the coating. The long-chain alkyl in montmorillonite can improve the dispersibility between montmorillonite flakes and improve the compatibility between montmorillonite and the polyethylene composition. The silane coupling agent with a reactive group can be connected to the montmorillonite and participate in the epoxy resin reaction to improve the compatibility between montmorillonite and the epoxy resin. By mixing the above-mentioned multiple raw materials, a coating system in which thermosetting resin and thermoplastic resin are evenly dispersed can be obtained. After thermal curing, the coating substrate obtained is a thermosetting resin and a thermoplastic resin that are mutually dispersed. The two form an interpenetrating network structure. The epoxy resin forms a cross-linked network, and the polyethylene can be interspersed in the epoxy resin. The two together form a coating material with a dense surface and interior, which has the advantages of both epoxy resin and polyethylene. In combination with fillers such as montmorillonite, higher corrosion resistance can be obtained.

[0029] The epoxy resin composition comprises an epoxy compound and at least two aliphatic polyamines. The epoxy groups of the epoxy compound and the amino groups of the aliphatic polyamines react to form a cross-linked and cured epoxy resin network. The aliphatic polyamine, as a curing agent, has high reactivity and can reduce the curing temperature of the epoxy resin composition, lower the application temperature of the coating, and improve the ease of construction. The mixture of at least two aliphatic polyamines can improve the fluidity of the polyamines and their compatibility with the epoxy resin. The aliphatic segments in the aliphatic polyamine can also improve the compatibility of the epoxy resin composition with polyethylene.

[0030] The polyethylene composition includes a first polyethylene and a second polyethylene with different molecular weights. Through the mixture of two polyethylenes with different molecular weights, the high molecular weight polyethylene can provide higher weather resistance and corrosion resistance, and the low molecular weight polyethylene can improve the fluidity of the polyethylene composition. The combination of the two makes the coating corrosion-resistant and easy to prepare and construct.

[0031] In some examples, relative to 100 parts by mass of the epoxy resin composition, the weight percentage of the polyethylene composition may be 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, etc.; the weight percentage of the long-chain alkyl-modified montmorillonite may be 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 ​​parts, 49 parts, 50 parts; the weight percentage of the silane coupling agent with a reactive group may be 3 parts, 4 parts, 5 parts, etc. Without departing from the spirit and principles of the present invention, each raw material component may be selected within any of the above weight percentages or ranges therebetween.

[0032] In some examples, the anti-corrosion powder coating is primarily composed of the following raw materials in parts by weight: 100 parts of an epoxy resin composition; 20-30 parts of a polyethylene composition; 30-50 parts of a long-chain alkyl-modified montmorillonite; and 3-5 parts of a silane coupling agent with a reactive group. In addition to the epoxy resin composition, polyethylene composition, long-chain alkyl-modified montmorillonite, and reactive group-containing silane coupling agent, the anti-corrosion powder coating may also contain other raw materials, with the weight content of the other raw materials not exceeding 10% of the total weight of the epoxy resin composition, polyethylene composition, long-chain alkyl-modified montmorillonite, and reactive group-containing silane coupling agent.

[0033] In some examples, the anti-corrosion powder coating comprises the following raw materials in parts by weight: 100 parts of an epoxy resin composition; 20-30 parts of a polyethylene composition; 30-50 parts of a long-chain alkyl-modified montmorillonite; and 3-5 parts of a silane coupling agent with a reactive group. Besides the epoxy resin composition, polyethylene composition, long-chain alkyl-modified montmorillonite, and reactive group-containing silane coupling agent, the anti-corrosion powder coating contains no other raw materials, simplifying the powder coating composition.

[0034] In some examples, the epoxy compound is selected from at least one of E12 epoxy resin and E14 epoxy resin. The epoxy compound can be, for example, E12 epoxy resin, E14 epoxy resin, or a mixture of E12 epoxy resin and E14 epoxy resin. Both E12 epoxy resin and E14 epoxy resin are solid bisphenol A epoxy resins, and the raw materials are readily available, which facilitates the preparation of solid powder coatings.

[0035] In some examples, the aliphatic polyamine is selected from hexamethylenediamine, octanediamine, and nonanediamine. Hexamethylenediamine, octanediamine, and nonanediamine can each be a diamine having a linear alkyl group with amino groups attached to both ends of the linear alkyl group. The alkyl groups in hexamethylenediamine, octanediamine, and nonanediamine have good compatibility with the polyethylene composition, and the amino groups can participate in epoxy curing. The at least two aliphatic polyamines in the epoxy resin composition can be hexamethylenediamine and octanediamine, hexamethylenediamine and nonanediamine, octanediamine and nonanediamine, or a mixture of hexamethylenediamine, octanediamine, and nonanediamine.

[0036] In some examples, the epoxy resin composition includes an epoxy compound to total aliphatic polyamine mass ratio of 1:(0.2-0.3), such as 1:0.2, 1:0.25, or 1:0.3. When the epoxy compound to total aliphatic polyamine mass ratio is within this range, the epoxy resin composition can be fully cured and crosslinked.

[0037] In some examples, in the epoxy resin composition, the mass proportion of any one aliphatic polyamine in the total aliphatic polyamines is not less than 30%, so that the mixture of multiple aliphatic polyamines can have better fluidity and compatibility with the epoxy resin.

[0038] In some examples, the first polyethylene is linear low-density polyethylene (LLDPE) with a number-average molecular weight of 60,000 to 80,000. LLDPE is typically polymerized by blending ethylene with a small amount of α-olefin. LLDPE exhibits excellent resistance to heat, cracking, acids, alkalis, and organic solvents. Furthermore, it exhibits excellent fluidity and rheological properties in a molten state, which can improve the preparation and application of coatings.

[0039] In some examples, the second polyethylene is high-density polyethylene (HDPE) with a number average molecular weight of 300,000 to 400,000. HDPE has high mechanical properties, low water absorption, high chemical stability, is insoluble in many organic solvents, is resistant to corrosion by acids, alkalis, and various salts, and has good weather resistance.

[0040] In some examples, the mass ratio of the first polyethylene to the second polyethylene is 1:(1-2), for example, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, etc. When the amounts of the first polyethylene and the second polyethylene are within the above ranges, good corrosion resistance and processability can be achieved.

[0041] In some examples, the long-chain alkyl modified montmorillonite is selected from at least one of hexadecyl quaternary ammonium salt modified montmorillonite and octadecyl quaternary ammonium salt modified montmorillonite. The hexadecyl quaternary ammonium salt modified montmorillonite can be obtained by modifying sodium montmorillonite with hexadecyltrimethylammonium bromide, and the octadecyl quaternary ammonium salt modified montmorillonite can be obtained by modifying sodium montmorillonite with octadecyltrimethylammonium bromide. The above-mentioned modification methods have been described in the prior art and will not be repeated here. The above-mentioned long-chain alkyl modified montmorillonite introduces long-chain alkyl groups into the montmorillonite. The long-chain alkyl groups can improve the compatibility between the montmorillonite and the polyethylene composition, and can cause the montmorillonite layers to peel off, improve the dispersibility of the montmorillonite, and help separate the flaky montmorillonite layers to achieve a better shielding effect.

[0042] In some examples, the reactive group-bearing silane coupling agent is selected from at least one of aminosiloxane and epoxysiloxane. For example, the aminosiloxane may be 3-aminopropyltriethoxysilane, and the epoxysiloxane may be γ-(2,3-epoxypropyloxy)propyltrimethoxysilane. The siloxane groups in the reactive group-bearing silane coupling agent are easily hydrolyzed and bonded to the montmorillonite. Reactive groups such as amino and epoxy groups can react with the epoxy compound or curing agent in the epoxy resin composition, thereby bonding to the cross-linked molecular chains of the epoxy resin, thereby improving the compatibility between the montmorillonite and the epoxy resin composition. The reactive group-bearing silane coupling agent can also improve the adhesion of the coating to a substrate, such as a metal substrate.

[0043] In some examples, the raw materials for the anti-corrosion powder coating further include additives, with the amount of additives being 1 to 10 parts by mass relative to 100 parts by mass of the epoxy resin composition. The anti-corrosion powder coating may be composed of an epoxy resin composition, a polyethylene composition, a long-chain alkyl-modified montmorillonite, a silane coupling agent with a reactive group, and additives. The additives may be selected from at least one of a pigment, a wetting agent, a dispersant, and a curing accelerator, and are used to color the coating, improve wettability to the substrate, improve the dispersibility of the raw materials, and promote the curing reaction, respectively.

[0044] In some examples, the method for preparing the anti-corrosion powder coating may include the following steps:

[0045] Step 1: Dispersing a silane coupling agent with a reactive group in a solvent to obtain a dispersion; spraying the dispersion onto the long-chain alkyl-modified montmorillonite, stirring evenly, and drying to obtain a filler powder. Specifically, in step 1, the silane coupling agent and the long-chain alkyl-modified montmorillonite are first mixed so that at least a portion of the silane coupling agent is attached to the long-chain alkyl-modified montmorillonite.

[0046] Step 2: Melt and mix the polyethylene composition and filler powder at a first temperature to obtain a mixture, so that the polyethylene composition and filler powder are evenly dispersed.

[0047] Step 3: Cooling the mixture, adding the epoxy resin composition to the mixture, melting and mixing at a second temperature, and cooling to form a powder. After the polyethylene composition and filler powder are mixed and dispersed, cooling the mixture and adding the epoxy resin composition to prevent premature curing of the epoxy resin composition.

[0048] The above preparation method is simple and the raw material components are evenly dispersed, which is beneficial for improving coating performance. Steps 2 and 3 can be carried out in an extruder with segmented temperature control and step-by-step feeding. Powder production can be achieved by granulation and pulverization.

[0049] In some examples, the solvent is at least one of water and ethanol. For example, the solvent can be water, ethanol, or a mixture of water and ethanol. The above solvents are non-toxic, environmentally friendly, and easily recyclable.

[0050] In some examples, the first temperature is 130-150° C., which can fully melt the first polyethylene and melt or soften the second polyethylene, thereby promoting uniform mixing and dispersion of the polyethylene composition and the filler powder.

[0051] In some examples, the second temperature is 90-110° C., which can allow the mixture and the epoxy resin composition to be melt-mixed and evenly dispersed.

[0052] In some examples, the above-mentioned anti-corrosion powder coating can be applied to a metal substrate. The specific steps can be spraying the anti-corrosion powder coating onto the surface of the metal substrate and then baking it to form an anti-corrosion coating on the surface of the metal substrate. The baking temperature can be, for example, 130 to 180°C, so that the epoxy resin composition is cured and the polyethylene composition is at least partially melted and flowed, filling the gaps in the coating to form a denser and smoother coating. The metal substrate can be, for example, metal in oil pipelines, ships, storage tanks, and engineering machinery. Baking can be carried out in an oven, or a heating device can be used to bake the metal surface.

[0053] The technical solution of the present invention will be described in detail below through specific examples. In the following examples or comparative examples, unless otherwise specified, substances with the same name refer to substances of the same origin and physical properties; raw materials are all commercially available or prepared using existing methods.

[0054] Example 1

[0055] The raw materials of the anti-corrosion powder coating of this embodiment are as follows:

[0056] 100 parts of an epoxy resin composition, wherein the epoxy resin composition is composed of an E12 epoxy resin, hexamethylenediamine, and octanediamine, wherein the mass ratio of hexamethylenediamine to octanediamine is 1:1, and the mass ratio of the E12 epoxy resin to the diamine is 1:0.3;

[0057] 20 parts of a polyethylene composition, wherein the polyethylene composition is composed of a linear low-density polyethylene (number average molecular weight of about 80,000) and a high-density polyethylene (number average molecular weight of about 300,000), and the mass ratio of the linear low-density polyethylene to the high-density polyethylene is 1:2;

[0058] 50 parts of sodium montmorillonite modified with hexadecyltrimethylammonium bromide;

[0059] 5 parts of 3-aminopropyltriethoxysilane;

[0060] 3 parts pigment.

[0061] The steps of the preparation method of the anti-corrosion powder coating of this embodiment are as follows:

[0062] Step 1: Dispersing 3-aminopropyltriethoxysilane in a mixed solvent of water and ethanol (volume ratio 1:1) to obtain a dispersion; spraying the dispersion on sodium montmorillonite modified with hexadecyltrimethylammonium bromide, stirring evenly, and drying to obtain a filler powder;

[0063] Step 2: Melt and mix the polyethylene composition, filler powder and pigment at 140° C. to obtain a mixture;

[0064] Step 3: Cool down to 110° C., add the epoxy resin composition into the mixture, melt and mix evenly at 110° C., and cool to form powder, which is the anti-corrosion powder coating.

[0065] The obtained anti-corrosion powder coating was sprayed onto the surface of the tinplate, and then baked at 150° C. to obtain a coating thickness of about 0.2 mm.

[0066] Example 2

[0067] The raw materials of the anti-corrosion powder coating of this embodiment are as follows:

[0068] 100 parts of an epoxy resin composition, wherein the epoxy resin composition is composed of an E14 epoxy resin, octanediamine, and nonanediamine, wherein the mass ratio of octanediamine to nonanediamine is 1:1, and the mass ratio of the E14 epoxy resin to the diamine is 1:0.2;

[0069] 30 parts of a polyethylene composition, wherein the polyethylene composition is composed of a linear low-density polyethylene (number average molecular weight of about 80,000) and a high-density polyethylene (number average molecular weight of about 300,000), and the mass ratio of the linear low-density polyethylene to the high-density polyethylene is 1:1;

[0070] 30 parts of sodium montmorillonite modified with octadecyltrimethylammonium bromide;

[0071] 3 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane;

[0072] 3 parts pigment.

[0073] The steps of the preparation method of the anti-corrosion powder coating of this embodiment are as follows:

[0074] Step 1: Dispersing γ-(2,3-epoxypropoxy)propyltrimethoxysilane in a mixed solvent of water and ethanol (volume ratio 1:1) to obtain a dispersion; spraying the dispersion on octadecyltrimethylammonium bromide-modified sodium montmorillonite, stirring evenly, and drying to obtain a filler powder;

[0075] Step 2: Melt and mix the polyethylene composition, filler powder and pigment at 140° C. to obtain a mixture;

[0076] Step 3: Cool down to 110° C., add the epoxy resin composition into the mixture, melt and mix evenly at 110° C., and cool to form powder, which is the anti-corrosion powder coating.

[0077] The obtained anti-corrosion powder coating was sprayed onto the surface of the tinplate, and then baked at 150° C. to obtain a coating thickness of about 0.2 mm.

[0078] Example 3

[0079] The raw materials of the anti-corrosion powder coating of this embodiment are as follows:

[0080] 100 parts of an epoxy resin composition, wherein the epoxy resin composition is composed of an E12 epoxy resin, hexamethylenediamine, and nonanediamine, wherein the mass ratio of hexamethylenediamine to nonanediamine is 3:7, and the mass ratio of the E12 epoxy resin to the diamine is 1:0.3;

[0081] 25 parts of a polyethylene composition, wherein the polyethylene composition is composed of a linear low-density polyethylene (number average molecular weight of about 80,000) and a high-density polyethylene (number average molecular weight of about 300,000), and the mass ratio of the linear low-density polyethylene to the high-density polyethylene is 1:1.5;

[0082] 40 parts of sodium montmorillonite modified with hexadecyltrimethylammonium bromide;

[0083] 4 parts of 3-aminopropyltriethoxysilane;

[0084] 3 parts pigment.

[0085] The steps of the preparation method of the anti-corrosion powder coating of this embodiment are as follows:

[0086] Step 1: Dispersing 3-aminopropyltriethoxysilane in a mixed solvent of water and ethanol (volume ratio 1:1) to obtain a dispersion; spraying the dispersion on sodium montmorillonite modified with hexadecyltrimethylammonium bromide, stirring evenly, and drying to obtain a filler powder;

[0087] Step 2: Melt and mix the polyethylene composition, filler powder and pigment at 140° C. to obtain a mixture;

[0088] Step 3: Cool down to 110° C., add the epoxy resin composition into the mixture, melt and mix evenly at 110° C., and cool to form powder, which is the anti-corrosion powder coating.

[0089] The obtained anti-corrosion powder coating was sprayed onto the surface of the tinplate, and then baked at 150° C. to obtain a coating thickness of about 0.2 mm.

[0090] Example 4

[0091] The raw materials of the anti-corrosion powder coating of this embodiment are as follows:

[0092] 100 parts of an epoxy resin composition, wherein the epoxy resin composition is composed of an E14 epoxy resin, hexamethylenediamine, octanediamine, and nonanediamine, wherein the mass ratio of hexamethylenediamine, octanediamine, and nonanediamine is 3:4:3, and the mass ratio of the E14 epoxy resin to the diamine is 1:0.2;

[0093] 25 parts of a polyethylene composition, wherein the polyethylene composition is composed of a linear low-density polyethylene (number average molecular weight of about 80,000) and a high-density polyethylene (number average molecular weight of about 300,000), and the mass ratio of the linear low-density polyethylene to the high-density polyethylene is 1:2;

[0094] 40 parts of sodium montmorillonite modified with octadecyltrimethylammonium bromide;

[0095] 4 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane;

[0096] 3 parts pigment.

[0097] The steps of the preparation method of the anti-corrosion powder coating of this embodiment are as follows:

[0098] Step 1: Dispersing γ-(2,3-epoxypropoxy)propyltrimethoxysilane in a mixed solvent of water and ethanol (volume ratio 1:1) to obtain a dispersion; spraying the dispersion on octadecyltrimethylammonium bromide-modified sodium montmorillonite, stirring evenly, and drying to obtain a filler powder;

[0099] Step 2: Melt and mix the polyethylene composition, filler powder and pigment at 140° C. to obtain a mixture;

[0100] Step 3: Cool down to 110° C., add the epoxy resin composition into the mixture, melt and mix evenly at 110° C., and cool to form powder, which is the anti-corrosion powder coating.

[0101] The obtained anti-corrosion powder coating was sprayed onto the surface of the tinplate, and then baked at 150° C. to obtain a coating thickness of about 0.2 mm.

[0102] Example 5

[0103] The raw materials of the anti-corrosion powder coating of this embodiment are as follows:

[0104] 100 parts of an epoxy resin composition, wherein the epoxy resin composition is composed of an E12 epoxy resin, hexamethylenediamine, and octanediamine, wherein the mass ratio of hexamethylenediamine to octanediamine is 1:9, and the mass ratio of the E12 epoxy resin to the diamine is 1:0.3;

[0105] 20 parts of a polyethylene composition, wherein the polyethylene composition is composed of a linear low-density polyethylene (number average molecular weight of about 80,000) and a high-density polyethylene (number average molecular weight of about 300,000), and the mass ratio of the linear low-density polyethylene to the high-density polyethylene is 1:2;

[0106] 50 parts of sodium montmorillonite modified with hexadecyltrimethylammonium bromide;

[0107] 5 parts of 3-aminopropyltriethoxysilane;

[0108] 3 parts pigment.

[0109] The steps of the preparation method of the anti-corrosion powder coating of this embodiment are as follows:

[0110] Step 1: Dispersing 3-aminopropyltriethoxysilane in a mixed solvent of water and ethanol (volume ratio 1:1) to obtain a dispersion; spraying the dispersion on sodium montmorillonite modified with hexadecyltrimethylammonium bromide, stirring evenly, and drying to obtain a filler powder;

[0111] Step 2: Melt and mix the polyethylene composition, filler powder and pigment at 140° C. to obtain a mixture;

[0112] Step 3: Cool down to 110° C., add the epoxy resin composition into the mixture, melt and mix evenly at 110° C., and cool to form powder, which is the anti-corrosion powder coating.

[0113] The obtained anti-corrosion powder coating was sprayed onto the surface of the tinplate, and then baked at 150° C. to obtain a coating thickness of about 0.2 mm.

[0114] Example 6

[0115] The raw materials of the anti-corrosion powder coating of this embodiment are as follows:

[0116] 100 parts of an epoxy resin composition, wherein the epoxy resin composition is composed of an E12 epoxy resin, hexamethylenediamine, and octanediamine, wherein the mass ratio of hexamethylenediamine to octanediamine is 1:1, and the mass ratio of the E12 epoxy resin to the diamine is 1:0.3;

[0117] 20 parts of a polyethylene composition, wherein the polyethylene composition is composed of a linear low-density polyethylene (number average molecular weight of about 80,000) and a high-density polyethylene (number average molecular weight of about 300,000), and the mass ratio of the linear low-density polyethylene to the high-density polyethylene is 1:5;

[0118] 50 parts of sodium montmorillonite modified with hexadecyltrimethylammonium bromide;

[0119] 5 parts of 3-aminopropyltriethoxysilane;

[0120] 3 parts pigment.

[0121] The steps of the preparation method of the anti-corrosion powder coating of this embodiment are as follows:

[0122] Step 1: Dispersing 3-aminopropyltriethoxysilane in a mixed solvent of water and ethanol (volume ratio 1:1) to obtain a dispersion; spraying the dispersion on sodium montmorillonite modified with hexadecyltrimethylammonium bromide, stirring evenly, and drying to obtain a filler powder;

[0123] Step 2: Melt and mix the polyethylene composition, filler powder and pigment at 140° C. to obtain a mixture;

[0124] Step 3: Cool down to 110° C., add the epoxy resin composition into the mixture, melt and mix evenly at 110° C., and cool to form powder, which is the anti-corrosion powder coating.

[0125] The obtained anti-corrosion powder coating was sprayed onto the surface of the tinplate, and then baked at 150° C. to obtain a coating thickness of about 0.2 mm.

[0126] Example 7

[0127] The raw materials of the anti-corrosion powder coating of this embodiment are as follows:

[0128] 100 parts of an epoxy resin composition, wherein the epoxy resin composition is composed of an E12 epoxy resin, hexamethylenediamine, and octanediamine, wherein the mass ratio of hexamethylenediamine to octanediamine is 1:1, and the mass ratio of the E12 epoxy resin to the diamine is 1:0.3;

[0129] 20 parts of a polyethylene composition, wherein the polyethylene composition is composed of a linear low-density polyethylene (number average molecular weight of about 80,000) and a high-density polyethylene (number average molecular weight of about 300,000), and the mass ratio of the linear low-density polyethylene to the high-density polyethylene is 1:0.2;

[0130] 50 parts of sodium montmorillonite modified with hexadecyltrimethylammonium bromide;

[0131] 5 parts of 3-aminopropyltriethoxysilane;

[0132] 3 parts pigment.

[0133] The steps of the preparation method of the anti-corrosion powder coating of this embodiment are as follows:

[0134] Step 1: Dispersing 3-aminopropyltriethoxysilane in a mixed solvent of water and ethanol (volume ratio 1:1) to obtain a dispersion; spraying the dispersion on sodium montmorillonite modified with hexadecyltrimethylammonium bromide, stirring evenly, and drying to obtain a filler powder;

[0135] Step 2: Melt and mix the polyethylene composition, filler powder and pigment at 140° C. to obtain a mixture;

[0136] Step 3: Cool down to 110° C., add the epoxy resin composition into the mixture, melt and mix evenly at 110° C., and cool to form powder, which is the anti-corrosion powder coating.

[0137] The obtained anti-corrosion powder coating was sprayed onto the surface of the tinplate, and then baked at 150° C. to obtain a coating thickness of about 0.2 mm.

[0138] Comparative Example 1

[0139] The weight parts of the raw materials of the powder coating of this comparative example are as follows:

[0140] 100 parts of an epoxy resin composition, wherein the epoxy resin composition is composed of an E12 epoxy resin and ethylenediamine, and the mass ratio of the E12 epoxy resin to the ethylenediamine is 1:0.3;

[0141] 20 parts of a polyethylene composition, wherein the polyethylene composition is composed of a linear low-density polyethylene (number average molecular weight of about 80,000) and a high-density polyethylene (number average molecular weight of about 300,000), and the mass ratio of the linear low-density polyethylene to the high-density polyethylene is 1:2;

[0142] 50 parts of sodium montmorillonite modified with hexadecyltrimethylammonium bromide;

[0143] 5 parts of 3-aminopropyltriethoxysilane;

[0144] 3 parts pigment.

[0145] The preparation method of the powder coating of this comparative example is as follows:

[0146] Step 1: Dispersing 3-aminopropyltriethoxysilane in a mixed solvent of water and ethanol (volume ratio 1:1) to obtain a dispersion; spraying the dispersion on sodium montmorillonite modified with hexadecyltrimethylammonium bromide, stirring evenly, and drying to obtain a filler powder;

[0147] Step 2: Melt and mix the polyethylene composition, filler powder and pigment at 140° C. to obtain a mixture;

[0148] Step 3: Cool down to 110° C., add the epoxy resin composition into the mixture, melt and mix evenly at 110° C., and cool to form powder, which is powder coating.

[0149] The obtained powder coating was sprayed onto the surface of the tinplate and then baked at 150° C. to obtain a coating thickness of about 0.2 mm.

[0150] Comparative Example 2

[0151] The weight parts of the raw materials of the powder coating of this comparative example are as follows:

[0152] 100 parts of an epoxy resin composition, wherein the epoxy resin composition is composed of an E12 epoxy resin, hexamethylenediamine, and octanediamine, wherein the mass ratio of hexamethylenediamine to octanediamine is 1:1, and the mass ratio of the E12 epoxy resin to the diamine is 1:0.3;

[0153] 20 parts of polyethylene, wherein the polyethylene is medium-density polyethylene (number average molecular weight of about 120,000);

[0154] 50 parts of sodium montmorillonite modified with hexadecyltrimethylammonium bromide;

[0155] 5 parts of 3-aminopropyltriethoxysilane;

[0156] 3 parts pigment.

[0157] The preparation method of the powder coating of this comparative example is as follows:

[0158] Step 1: Dispersing 3-aminopropyltriethoxysilane in a mixed solvent of water and ethanol (volume ratio 1:1) to obtain a dispersion; spraying the dispersion on sodium montmorillonite modified with hexadecyltrimethylammonium bromide, stirring evenly, and drying to obtain a filler powder;

[0159] Step 2: Melt and mix the polyethylene, filler powder and pigment at 140° C. to obtain a mixture;

[0160] Step 3: Cool down to 110° C., add the epoxy resin composition into the mixture, melt and mix evenly at 110° C., and cool to form powder, which is powder coating.

[0161] The obtained powder coating was sprayed onto the surface of the tinplate and then baked at 150° C. to obtain a coating thickness of about 0.2 mm.

[0162] Comparative Example 3

[0163] The weight parts of the raw materials of the powder coating of this comparative example are as follows:

[0164] 100 parts of an epoxy resin composition, wherein the epoxy resin composition is composed of an E12 epoxy resin, hexamethylenediamine, and octanediamine, wherein the mass ratio of hexamethylenediamine to octanediamine is 1:1, and the mass ratio of the E12 epoxy resin to the diamine is 1:0.3;

[0165] 20 parts of a polyethylene composition, wherein the polyethylene composition is composed of a linear low-density polyethylene (number average molecular weight of about 80,000) and a high-density polyethylene (number average molecular weight of about 300,000), and the mass ratio of the linear low-density polyethylene to the high-density polyethylene is 1:2;

[0166] 50 parts of unmodified montmorillonite;

[0167] 5 parts of 3-aminopropyltriethoxysilane;

[0168] 3 parts pigment.

[0169] The preparation method of the powder coating of this comparative example comprises the following steps:

[0170] Step 1: dispersing 3-aminopropyltriethoxysilane in a mixed solvent of water and ethanol (volume ratio 1:1) to obtain a dispersion; spraying the dispersion on montmorillonite, stirring evenly, and drying to obtain a filler powder;

[0171] Step 2: Melt and mix the polyethylene composition, filler powder and pigment at 140° C. to obtain a mixture;

[0172] Step 3: Cool down to 110° C., add the epoxy resin composition into the mixture, melt and mix evenly at 110° C., and cool to form powder, which is powder coating.

[0173] The obtained powder coating was sprayed onto the surface of the tinplate and then baked at 150° C. to obtain a coating thickness of about 0.2 mm.

[0174] Comparative Example 4

[0175] The weight parts of the raw materials of the powder coating of this comparative example are as follows:

[0176] 100 parts of an epoxy resin composition, wherein the epoxy resin composition is composed of an E12 epoxy resin, hexamethylenediamine, and octanediamine, wherein the mass ratio of hexamethylenediamine to octanediamine is 1:1, and the mass ratio of the E12 epoxy resin to the diamine is 1:0.3;

[0177] 50 parts of a polyethylene composition, wherein the polyethylene composition is composed of a linear low-density polyethylene (number average molecular weight of about 80,000) and a high-density polyethylene (number average molecular weight of about 300,000), and the mass ratio of the linear low-density polyethylene to the high-density polyethylene is 1:2;

[0178] 50 parts of sodium montmorillonite modified with hexadecyltrimethylammonium bromide;

[0179] 5 parts of 3-aminopropyltriethoxysilane;

[0180] 3 parts pigment.

[0181] The preparation method of the powder coating of this comparative example is as follows:

[0182] Step 1: Dispersing 3-aminopropyltriethoxysilane in a mixed solvent of water and ethanol (volume ratio 1:1) to obtain a dispersion; spraying the dispersion on sodium montmorillonite modified with hexadecyltrimethylammonium bromide, stirring evenly, and drying to obtain a filler powder;

[0183] Step 2: Melt and mix the polyethylene composition, filler powder and pigment at 140° C. to obtain a mixture;

[0184] Step 3: Cool down to 110° C., add the epoxy resin composition into the mixture, melt and mix evenly at 110° C., and cool to form powder, which is powder coating.

[0185] The obtained powder coating was sprayed onto the surface of the tinplate and then baked at 150° C. to obtain a coating thickness of about 0.2 mm.

[0186] Performance Testing

[0187] The powder coatings and coatings obtained in the above examples and comparative examples were tested for adhesion, corrosion resistance, and weather resistance. Adhesion was tested in accordance with GB9286-98; water resistance was tested in accordance with GB / T1733-1993 for 120 days; salt water resistance, alkali resistance, and acid resistance were tested in accordance with GB / T 9274-1988 for 120 days, with salt water resistance tested using a 20% NaCl solution, alkali resistance tested using a 10% NaOH solution, and acid resistance tested using a 10% H2SO4 solution. Organic solvent resistance was tested in accordance with GB / T 23989-2009, using xylene as the solvent, room temperature, a pressure of 2 kg, and 50 wipes. Weather resistance was tested in accordance with GB1865-2009, followed by xenon lamp accelerated aging, and then adhesion and salt water resistance tests (120 days) were performed in accordance with GB9286-98 and GB / T9274-1988.

[0188] The test results are shown in Table 1 below.

[0189] Table 1 Test results of the embodiments and comparative examples

[0190]

[0191] The above test results show that the powder coating of the present invention has good adhesion to the metal substrate, and has good water resistance, salt water resistance, alkali resistance, acid resistance and organic solvent resistance, and has good weather resistance. It can still maintain good adhesion and corrosion resistance after accelerated aging.

[0192] Finally, it should be emphasized that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. An anti-corrosion powder coating, characterized in that Including the following raw materials by weight: 100 parts of epoxy resin composition; 20-30 parts of polyethylene composition; 30-50 parts of long-chain alkyl modified montmorillonite; 3-5 parts of a silane coupling agent with a reactive group; Wherein, the epoxy resin composition comprises an epoxy compound and at least two aliphatic polyamines; The polyethylene composition includes a first polyethylene and a second polyethylene having different molecular weights; The epoxy compound is selected from at least one of E12 epoxy resin and E14 epoxy resin; The aliphatic polyamine is selected from hexamethylenediamine, octanediamine, and nonanediamine; The mass ratio of the epoxy compound to the aliphatic polyamine in the epoxy resin composition is 1:(0.2-0.3); In the epoxy resin composition, the mass proportion of any one of the aliphatic polyamines in the total mass of the aliphatic polyamines is not less than 30%; The first polyethylene is a linear low-density polyethylene with a number average molecular weight of 60,000 to 80,000; The second polyethylene is a high-density polyethylene with a number average molecular weight of 300,000 to 400,000; The mass ratio of the first polyethylene to the second polyethylene is 1:(1-2); The preparation method of the anti-corrosion powder coating is: Step 1: dispersing a silane coupling agent with a reactive group in a solvent to obtain a dispersion; spraying the dispersion onto the long-chain alkyl-modified montmorillonite, stirring evenly, and drying to obtain a filler powder; Step 2: Melting and mixing the polyethylene composition and the filler powder at a first temperature to obtain a mixture; the first temperature is 130-150° C.; Step 3: Cooling, adding the epoxy resin composition to the mixture, melting and mixing at a second temperature, and cooling to form a powder; the second temperature is 90-110° C.; Steps 2 and 3 are carried out in an extruder with segmented temperature control and segmented feeding.

2. The anti-corrosion powder coating according to claim 1, characterized in that: The long-chain alkyl modified montmorillonite is selected from at least one of hexadecyl quaternary ammonium salt modified montmorillonite and octadecyl quaternary ammonium salt modified montmorillonite.

3. An anti-corrosion powder coating according to claim 1 or 2, characterized in that: The silane coupling agent with a reactive group is selected from at least one of aminosiloxane and epoxysiloxane.

4. An anti-corrosion powder coating according to claim 1 or 2, characterized in that: The raw materials further include additives, with the mass fraction of the additives being 1 to 10 parts relative to 100 parts by mass of the epoxy resin composition; The additive is selected from at least one of a pigment, a wetting agent, a dispersant, and a curing accelerator.

5. The method for preparing an anti-corrosion powder coating according to any one of claims 1 to 4, characterized in that The following steps are involved: Step 1: dispersing a silane coupling agent with a reactive group in a solvent to obtain a dispersion; spraying the dispersion onto the long-chain alkyl-modified montmorillonite, stirring evenly, and drying to obtain a filler powder; Step 2: Melting and mixing the polyethylene composition and the filler powder at a first temperature to obtain a mixture; the first temperature is 130-150° C.; Step 3: Cooling, adding the epoxy resin composition to the mixture, melting and mixing at a second temperature, and cooling to form a powder; the second temperature is 90-110° C.; Steps 2 and 3 are carried out in an extruder with segmented temperature control and segmented feeding.

6. The preparation method according to claim 5, characterized in that: The solvent is at least one of water and ethanol.

7. Use of an anti-corrosion powder coating according to any one of claims 1 to 4, characterized in that The following steps are involved: The anti-corrosion powder coating is sprayed onto the surface of a metal substrate and then baked.

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