Open fire resistant powder coating as well as preparation method and application thereof

Abstract

The invention relates to an open-fire-resistant powder coating as well as a preparation method and application thereof. The open-fire-resistant powder coating comprises the following raw materials in parts by mass: 100 parts of novolac epoxy resin; 20 to 30 parts of aromatic ternary amine; 10 to 20 parts of amino-terminated polydimethylsiloxane; 10 to 20 parts of polyphenyl methyl siloxane; 10 to 15 parts of pentaerythritol glycidyl ether; 5 to 10 parts of hexaphenoxy cyclotriphosphazene; and 60-80 parts of an inorganic filler. The open fire resistant powder coating can resist open fire for a long time.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to an open flame resistant powder coating and a preparation method and application thereof. Background Art

[0002] Powder coating is a kind of coating in the form of fine powder. Because it does not use solvents, it has the advantages of environmental protection, safety, and high efficiency. Among them, thermosetting powder coating is a powder coating prepared with thermosetting resin. After the thermosetting powder coating is applied to the object, the coating is cured by heating and other means to obtain a cross-linked resin film, which is the cured coating. The coating formed by thermosetting powder coating can usually withstand higher temperatures because of its cross-linked structure.

[0003] Fire-resistant coating is a kind of coating with fire resistance, which can be used in stoves, flues, cooking utensils, heaters, etc. Thermosetting powder coating has good application prospects in fire-resistant coating, however, some current powder coatings are easy to crack and damage when exposed to open flame for a long time. Summary of the invention

[0004] In view of the deficiencies in the prior art, the first object of the present invention is to provide a flame-resistant powder coating that can withstand open flames for a long time.

[0005] The second object of the present invention is to provide a method for preparing the open flame resistant powder coating, which has the advantages of simple steps and the like.

[0006] The third object of the present invention is to provide application of the flame resistant powder coating.

[0007] To achieve the first purpose of the present invention, the present invention provides a flame-resistant powder coating, which includes the following raw materials in parts by mass: 100 parts of phenolic epoxy resin; 20 to 30 parts of aromatic triamine; 10 to 20 parts of amino-terminated polydimethylsiloxane; 10 to 20 parts of polyphenyl methylsiloxane; 10 to 15 parts of pentaerythritol glycidyl ether; 5 to 10 parts of hexaphenoxy cyclotriphosphazene; and 60 to 80 parts of inorganic filler.

[0008] In some embodiments of the present invention, the open flame resistant powder coating comprises the following raw materials in parts by mass: 100 parts of phenolic epoxy resin; 25 to 30 parts of aromatic triamine; 10 to 15 parts of amino-terminated polydimethylsiloxane; 15 to 20 parts of polyphenyl methylsiloxane; 10 to 12 parts of pentaerythritol glycidyl ether; 8 to 10 parts of hexaphenoxy cyclotriphosphazene; and 70 to 80 parts of inorganic filler.

[0009] In some embodiments of the present invention, the inorganic filler includes at least one of flaky aluminum oxide, ceramic powder, and silicon dioxide.

[0010] In some embodiments of the present invention, the particle size of the flaky aluminum oxide is 3 to 15 μm, the particle size of the ceramic powder is 1 to 20 μm, and the particle size of the silicon dioxide is 1 to 50 μm.

[0011] In some embodiments of the present invention, the inorganic filler is a mixture of flaky aluminum oxide and at least one of ceramic powder and silicon dioxide, and the mass content of the flaky aluminum oxide in the inorganic filler is 20-30%.

[0012] In some embodiments of the present invention, the weight average molecular weight of the amino-terminated polydimethylsiloxane is 1000-1500.

[0013] In some embodiments of the present invention, the weight average molecular weight of the polyphenylmethylsiloxane is 2500-3000.

[0014] In some embodiments of the present invention, the phenolic epoxy resin is at least one of NPCN-702 and NPCN-704.

[0015] In some embodiments of the present invention, the aromatic triamine is at least one of triphenylamine, 1,3,5-tris(4-aminophenyl)benzene, and N,N',N"-triphenyl-1,3,5-benzenetriamine.

[0016] To achieve the second purpose of the present invention, the present invention provides a method for preparing an open flame resistant powder coating as described in any of the above schemes, which comprises the following steps: Step 1: heating and mixing terminal amino polydimethylsiloxane, polyphenyl methylsiloxane and pentaerythritol glycidyl ether at a first temperature to obtain a first mixture; Step 2: heating and mixing the first mixture, phenolic epoxy resin, aromatic triamine, hexaphenoxy cyclotriphosphazene and inorganic filler at a second temperature to obtain an open flame resistant powder coating.

[0017] In some embodiments of the present invention, in step 1, the first temperature is 120-130° C., and the time for heating and mixing at the first temperature is 10-20 minutes.

[0018] In some embodiments of the present invention, in step 2, the second temperature is 90-100° C., and the time for heating and mixing at the first temperature is 5-10 minutes.

[0019] In some embodiments of the present invention, the step 2 is performed in a twin-screw extruder.

[0020] To achieve the third object of the present invention, the present invention provides a coating formed by heating and curing the open flame resistant powder coating described in any of the above schemes.

[0021] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0022] The open flame resistant powder coating of the present invention adopts phenolic epoxy resin and aromatic triamine to form an epoxy resin system, and the epoxy resin has a high degree of crosslinking and good high temperature resistance. The present invention also adopts amino-terminated polydimethylsiloxane and polyphenylmethylsiloxane to provide polysiloxane segments to improve the high temperature resistance of the resin, and cooperates with pentaerythritol glycidyl ether, hexaphenoxy cyclotriphosphazene, etc. to improve the high temperature resistance and flame retardancy of the resin system. The open flame resistant powder coating of the present invention also adds more high temperature resistant and flame retardant inorganic fillers to improve the high temperature resistance and flame retardancy of the coating. Under the mutual cooperation of the above-mentioned multiple components, the open flame resistant powder coating of the present invention obtains a coating that can withstand open flames for a long time. DETAILED DESCRIPTION

[0023] The embodiment of the present invention provides a flame-resistant powder coating, which can withstand open flames for a long time and maintain the adhesion and mechanical strength of the coating under the action of open flames for a long time. The flame-resistant powder coating can be used for stoves, flues, cooking utensils, heaters, and can also be used in other application scenarios with high temperature and open flames.

[0024] Specifically, the open flame resistant powder coating comprises the following raw materials in parts by mass: 100 parts of phenolic epoxy resin; 20 to 30 parts of aromatic triamine; 10 to 20 parts of amino-terminated polydimethylsiloxane; 10 to 20 parts of polyphenylmethylsiloxane; 10 to 15 parts of pentaerythritol glycidyl ether; 5 to 10 parts of hexaphenoxy cyclotriphosphazene; and 60 to 80 parts of inorganic filler.

[0025] Wherein, the novolac epoxy resin can be at least one of phenol novolac epoxy resin, o-cresol novolac epoxy resin, bisphenol A novolac epoxy resin, etc., and the novolac epoxy resin contains a large amount of phenyl and epoxy groups, and the phenyl group can improve the mechanical properties and high temperature resistance of the resin, and the epoxy group can react with the amino group to obtain a resin system with a high degree of crosslinking. Aromatic teramines contain phenyl and amino groups, and the phenyl group can improve the mechanical properties and high temperature resistance of the resin. The amino group, as a curing group of the epoxy group, can improve the degree of crosslinking of the resin. The amino-terminated polydimethylsiloxane introduces a siloxane chain that is resistant to high temperatures and has good flame retardancy to the resin system, and the amino-terminated group can react with the epoxy group, and the polydimethylsiloxane is introduced into the resin system, so that the polysiloxane is evenly dispersed and tightly combined in the resin system. The polyphenylmethylsiloxane molecular chain contains phenyl and polysiloxane segments, which can improve the high temperature resistance and flame retardancy of the system, and the polyphenylmethylsiloxane has good compatibility with the amino-terminated polydimethylsiloxane, and the polyphenylmethylsiloxane can be uniformly dispersed in the resin system with the amino-terminated polydimethylsiloxane. Pentaerythritol glycidyl ether is a polyepoxy compound, which can adjust the crosslinking degree and compactness of the resin system, thereby improving the high temperature resistance and flame retardancy of the resin system. Hexaphenoxy cyclotriphosphazene contains a large amount of phenyl and phosphorus nitrogen ring, which can also improve the high temperature resistance and flame retardancy of the resin system. The resin system also contains a large amount of inorganic fillers to further improve the high temperature resistance and flame retardancy. The raw materials of the above-mentioned multiple components cooperate with each other in a specific dosage ratio, which can improve the long-term open flame resistance of the coating formed by the open flame resistant powder coating, so that the coating maintains good adhesion and mechanical properties under long-term open flames.

[0026] In some examples of this embodiment, relative to 100 parts by mass of phenolic epoxy resin, the mass parts of aromatic triamine can 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 mass parts of amino-terminated polydimethylsiloxane can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, etc.; the mass parts of polyphenylmethylsiloxane can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, etc. , 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, etc.; pentaerythritol glycidyl ether 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, etc.; the mass parts of hexaphenoxy cyclotriphosphazene can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc.; the mass parts of inorganic filler can be 60 parts, 61 parts, 62 parts, 63 parts, 64 parts, 65 parts, 66 parts, 67 parts, 68 parts, 69 parts, 70 parts, 71 parts, 72 parts, 73 parts, 74 parts, 75 parts, 76 parts, 77 parts, 78 parts, 79 parts, 80 parts, etc.

[0027] In some examples of the present embodiment, the open flame resistant powder coating is mainly composed of the following raw materials in parts by mass: 100 parts of phenolic epoxy resin; 20 to 30 parts of aromatic triamine; 10 to 20 parts of amino-terminated polydimethylsiloxane; 10 to 20 parts of polyphenylmethylsiloxane; 10 to 15 parts of pentaerythritol glycidyl ether; 5 to 10 parts of hexaphenoxy cyclotriphosphazene; and 60 to 80 parts of inorganic filler. In addition to the phenolic epoxy resin, aromatic triamine, amino-terminated polydimethylsiloxane, polyphenylmethylsiloxane, pentaerythritol glycidyl ether, hexaphenoxy cyclotriphosphazene, and inorganic filler, the open flame resistant powder coating may also contain a small amount of, for example, 1 to 10 parts by mass of an auxiliary agent, such as a pigment.

[0028] In some examples of the present embodiment, the open flame resistant powder coating is composed of the following raw materials in parts by mass: 100 parts of phenolic epoxy resin; 20 to 30 parts of aromatic triamine; 10 to 20 parts of amino-terminated polydimethylsiloxane; 10 to 20 parts of polyphenylmethylsiloxane; 10 to 15 parts of pentaerythritol glycidyl ether; 5 to 10 parts of hexaphenoxy cyclotriphosphazene; and 60 to 80 parts of inorganic filler. In addition to phenolic epoxy resin, aromatic triamine, amino-terminated polydimethylsiloxane, polyphenylmethylsiloxane, pentaerythritol glycidyl ether, hexaphenoxy cyclotriphosphazene, and inorganic filler, the open flame resistant powder coating does not contain other raw materials, and the composition is simpler.

[0029] In some examples of this embodiment, the flame-resistant powder coating includes the following raw materials in parts by mass: 100 parts of phenolic epoxy resin; 25-30 parts of aromatic triamine; 10-15 parts of amino-terminated polydimethylsiloxane; 15-20 parts of polyphenylmethylsiloxane; 12-15 parts of pentaerythritol glycidyl ether; 8-10 parts of hexaphenoxy cyclotriphosphazene; 70-80 parts of inorganic filler. When the amount of each component is within the above range, the resulting coating has better fire resistance.

[0030] In some examples of this embodiment, the inorganic filler includes at least one of flaky aluminum oxide, ceramic powder, and silicon dioxide. The raw materials of the above inorganic filler are easily available, high temperature resistant and fire resistant, and can improve the high temperature resistance and fire resistance of the coating.

[0031] In some examples of this embodiment, the particle size of the flaky aluminum oxide is 3 to 15 μm, the particle size of the ceramic powder is 1 to 20 μm, and the particle size of the silicon dioxide is 1 to 50 μm. When the particle size of the above filler is within the above range, the filler is evenly dispersed in the resin system and has good heat resistance and flame retardancy. The particle size of the flaky aluminum oxide refers to the average diameter of its flaky plane.

[0032] In some examples of this embodiment, the inorganic filler is a mixture of flaky aluminum oxide and at least one of ceramic powder and silicon dioxide, and the mass content of flaky aluminum oxide in the inorganic filler is 20-30%, that is, the mass of flaky aluminum oxide accounts for 20-30% of the total mass of the inorganic filler. The use of flaky fillers in combination with ordinary spherical or quasi-spherical fillers helps to further improve the flame resistance of the coating.

[0033] In some examples of this embodiment, the weight average molecular weight of terminal amino polydimethylsiloxane is 1000-1500, and the weight average molecular weight of polyphenylmethylsiloxane is 2500-3000. When the molecular weight of the polysiloxane raw material is within the above range, the coating has good fire resistance and the raw material is easy to disperse.

[0034] In some examples of this embodiment, the phenolic epoxy resin is at least one of NPCN-702 and NPCN-704. The phenolic epoxy resin comes from Kunshan Nan Ya, has a high epoxy content, and helps to maintain the particle morphology of the powder coating and improve storage stability.

[0035] In some examples of this embodiment, the aromatic triamine is at least one of isophthalic acid, 1,3,5-tri(4-aminophenyl)benzene, and N,N',N"-triphenyl-1,3,5-benzenetriamine. The above triamines contain three amino groups in one molecule, which is beneficial to increase the crosslinking density of the resin system.

[0036] In some examples of the present embodiment, the preparation method of the above-mentioned open flame resistant powder coating may include the following steps: Step 1: Heat and mix terminal amino polydimethylsiloxane, polyphenyl methylsiloxane and pentaerythritol glycidyl ether at a first temperature to obtain a first mixture; Step 2: Heat and mix the first mixture, phenolic epoxy resin, aromatic triamine, hexaphenoxy cyclotriphosphazene and inorganic filler at a second temperature to obtain an open flame resistant powder coating.

[0037] In the preparation process of the open flame resistant powder coating of the present embodiment, amino-terminated polydimethylsiloxane, polyphenyl methylsiloxane and pentaerythritol glycidyl ether are first mixed, and the amino-terminated polydimethylsiloxane and pentaerythritol glycidyl ether can be partially polycondensed to obtain a pre-condensation product with a relatively increased molecular weight, which is convenient for the powder coating to maintain a dry granular state and is beneficial to the mixing and dispersion of the polyphenyl methylsiloxane end and the amino polydimethylsiloxane; then the obtained mixture is mixed with other raw materials and granulated evenly to obtain the desired powder coating. The preparation method is simple and the production efficiency is high.

[0038] In some examples of this embodiment, in step one, the first temperature is 120-130° C., and the time for heating and mixing at the first temperature is 10-20 minutes, which facilitates the uniform dispersion of the amino-terminated polydimethylsiloxane, polyphenyl methylsiloxane and pentaerythritol glycidyl ether and helps the pre-condensation of the amino-terminated polydimethylsiloxane and pentaerythritol glycidyl ether.

[0039] In some examples of this embodiment, in step 2, the second temperature is 90-100° C., and the time for heating and mixing at the first temperature is 5-10 minutes, which helps to evenly disperse the raw materials and avoid premature cross-linking of the resin system.

[0040] In some examples of this embodiment, step 2 is carried out in a twin-screw extruder, which is easy to operate.

[0041] In some examples of this embodiment, this embodiment also provides a coating prepared from the above-mentioned flame-resistant coating, which can maintain good adhesion and mechanical strength under long-term open flames and protect the coated objects from being damaged by open flames. The coating can be used for stoves, flues, heaters, reactors, cooking utensils, etc.

[0042] The flame resistant powder coating of the present invention will be further described in detail below through specific examples.

[0043] Example 1

[0044] The steps for preparing the flame resistant powder coating of this embodiment are as follows:

[0045] Step 1: heating 10 parts of amino-terminated polydimethylsiloxane with a weight average molecular weight of about 1000, 15 parts of polyphenylmethylsiloxane with a weight average molecular weight of about 2500 and 12 parts of pentaerythritol glycidyl ether at about 120° C. for 20 minutes and mixing them uniformly to obtain a first mixture;

[0046] Step 2: melt-extrude the entire first mixture, 100 parts of phenolic epoxy resin NPCN-702, 30 parts of 1,3,5-tris(4-aminophenyl)benzene, 10 parts of hexaphenoxycyclotriphosphazene and 80 parts of inorganic filler (a mixture of flaky alumina with a particle size of 5 to 15 μm and silica with a particle size of 5 to 20 μm, with flaky alumina accounting for 20% of the total amount) at about 100°C, and crush after cooling to obtain a flame-resistant powder coating.

[0047] Example 2

[0048] The steps for preparing the flame resistant powder coating of this embodiment are as follows:

[0049] Step 1: heating 15 parts of amino-terminated polydimethylsiloxane with a weight average molecular weight of about 1500, 20 parts of polyphenylmethylsiloxane with a weight average molecular weight of about 3000 and 10 parts of pentaerythritol glycidyl ether at about 130° C. for 10 minutes and mixing them uniformly to obtain a first mixture;

[0050] Step 2: melt-extrude all the first mixture, 100 parts of phenolic epoxy resin NPCN-704, 25 parts of N,N',N"-triphenyl-1,3,5-benzenetriamine, 8 parts of hexaphenoxy cyclotriphosphazene and 70 parts of inorganic filler (a mixture of flaky alumina with a particle size of 3 to 10 μm and ceramic powder with a particle size of 10 to 40 μm, with flaky alumina accounting for 30% of the total amount) at about 100°C, and crush after cooling to obtain a flame-resistant powder coating.

[0051] Example 3

[0052] The steps for preparing the flame resistant powder coating of this embodiment are as follows:

[0053] Step 1: heating 20 parts of amino-terminated polydimethylsiloxane with a weight average molecular weight of about 1200, 15 parts of polyphenylmethylsiloxane with a weight average molecular weight of about 2700 and 15 parts of pentaerythritol glycidyl ether at about 130° C. for 10 minutes and mixing them uniformly to obtain a first mixture;

[0054] Step 2: melt-extrude all the first mixture, 100 parts of phenolic epoxy resin NPCN-704, 20 parts of isophenyltriamine, 5 parts of hexaphenoxy cyclotriphosphazene and 60 parts of inorganic filler (a mixture of flaky aluminum oxide with a particle size of 3 to 10 μm and silicon dioxide with a particle size of 20 to 50 μm, with the flaky aluminum oxide accounting for 30% of the total amount) at about 100° C., and crush after cooling to obtain a flame-resistant powder coating.

[0055] Example 4

[0056] The steps for preparing the flame resistant powder coating of this embodiment are as follows:

[0057] Step 1: heating 15 parts of amino-terminated polydimethylsiloxane with a weight average molecular weight of about 1000, 15 parts of polyphenylmethylsiloxane with a weight average molecular weight of about 3000 and 12 parts of pentaerythritol glycidyl ether at about 120° C. for 20 minutes and mixing them evenly to obtain a first mixture;

[0058] Step 2: melt-extrude all the first mixture, 100 parts of phenolic epoxy resin NPCN-702, 30 parts of 1,3,5-tris(4-aminophenyl)benzene, 10 parts of hexaphenoxycyclotriphosphazene and 80 parts of inorganic filler (flaky aluminum oxide with a particle size of 3 to 10 μm) at about 90° C., and crush them after cooling to obtain a flame-resistant powder coating.

[0059] Example 5

[0060] The steps for preparing the flame resistant powder coating of this embodiment are as follows:

[0061] Step 1: heating 10 parts of amino-terminated polydimethylsiloxane with a weight average molecular weight of about 1200, 20 parts of polyphenylmethylsiloxane with a weight average molecular weight of about 2500 and 10 parts of pentaerythritol glycidyl ether at about 120° C. for 15 minutes and mixing them uniformly to obtain a first mixture;

[0062] Step 2: melt-extrude the entire first mixture, 100 parts of phenolic epoxy resin NPCN-704, 25 parts of isophenyltriamine, 8 parts of hexaphenoxy cyclotriphosphazene and 70 parts of inorganic filler (a mixture of flaky alumina with a particle size of 3 to 10 μm and ceramic powder with a particle size of 10 to 40 μm, with the flaky alumina accounting for 50% of the total amount) at about 100° C., and crush after cooling to obtain a flame-resistant powder coating.

[0063] Example 6

[0064] The steps for preparing the flame resistant powder coating of this embodiment are as follows:

[0065] Step 1: heating 15 parts of amino-terminated polydimethylsiloxane with a weight average molecular weight of about 1500, 15 parts of polyphenylmethylsiloxane with a weight average molecular weight of about 3500 and 12 parts of pentaerythritol glycidyl ether at about 130° C. for 10 minutes and mixing them uniformly to obtain a first mixture;

[0066] Step 2: melt-extrude the entire first mixture, 100 parts of phenolic epoxy resin NPCN-702, 25 parts of N,N',N"-triphenyl-1,3,5-benzenetriamine, 10 parts of hexaphenoxy cyclotriphosphazene and 80 parts of inorganic filler (a mixture of flaky alumina with a particle size of 5 to 15 μm and a ceramic powder with a particle size of 5 to 20 μm, with the flaky alumina accounting for 20% of the total amount) at about 100°C, and crush after cooling to obtain a flame-resistant powder coating.

[0067] Example 7

[0068] The steps for preparing the flame resistant powder coating of this embodiment are as follows:

[0069] 10 parts of amino-terminated polydimethylsiloxane with a weight average molecular weight of about 1000, 15 parts of polyphenylmethylsiloxane with a weight average molecular weight of about 2500, 12 parts of pentaerythritol glycidyl ether, 100 parts of phenolic epoxy resin NPCN-702, 30 parts of 1,3,5-tris(4-aminophenyl)benzene, 10 parts of hexaphenoxycyclotriphosphazene and 80 parts of inorganic filler (a mixture of flaky aluminum oxide with a particle size of 5 to 15 μm and silicon dioxide with a particle size of 5 to 20 μm, with the flaky aluminum oxide accounting for 20% of the total amount) are mixed uniformly in a blender, melt-extruded at about 100°C, and pulverized after cooling to obtain a flame-resistant powder coating.

[0070] Comparative Example 1

[0071] The powder coating preparation steps of this comparative example are as follows:

[0072] 100 parts of phenolic epoxy resin NPCN-702, 30 parts of 1,3,5-tris(4-aminophenyl)benzene, 12 parts of pentaerythritol glycidyl ether, 10 parts of hexaphenoxycyclotriphosphazene and 80 parts of inorganic filler (a mixture of flaky alumina with a particle size of 3 to 10 μm and ceramic powder with a particle size of 10 to 40 μm, with the flaky alumina accounting for 30% of the total) are melt-extruded at about 100°C, and crushed after cooling to obtain a powder coating.

[0073] Comparative Example 2

[0074] The powder coating preparation steps of this comparative example are as follows:

[0075] Step 1: heating 10 parts of amino-terminated polydimethylsiloxane with a weight average molecular weight of about 1200, 10 parts of polyphenylmethylsiloxane with a weight average molecular weight of about 2500 and 12 parts of pentaerythritol glycidyl ether at about 120° C. for 20 minutes and mixing them uniformly to obtain a first mixture;

[0076] Step 2: melt-extrude the entire first mixture, 100 parts of phenolic epoxy resin NPCN-702, 30 parts of 1,3,5-tris(4-aminophenyl)benzene and 90 parts of inorganic filler (a mixture of flaky alumina with a particle size of 3 to 10 μm and ceramic powder with a particle size of 10 to 40 μm, with the flaky alumina accounting for 30% of the total amount) at about 100°C, and pulverize after cooling to obtain a powder coating.

[0077] Comparative Example 3

[0078] The powder coating preparation steps of this comparative example are as follows:

[0079] Step 1: heating 10 parts of amino-terminated polydimethylsiloxane with a weight average molecular weight of about 1000, 15 parts of polyphenylmethylsiloxane with a weight average molecular weight of about 2500 and 12 parts of pentaerythritol glycidyl ether at about 130° C. for 10 minutes and mixing them evenly to obtain a first mixture;

[0080] Step 2: melt-extrude the entire first mixture, 100 parts of phenolic epoxy resin NPCN-702, 30 parts of meta-xylylenediamine, 10 parts of hexaphenoxy cyclotriphosphazene and 80 parts of inorganic filler (a mixture of flaky alumina with a particle size of 3 to 10 μm and ceramic powder with a particle size of 10 to 40 μm, with the flaky alumina accounting for 30% of the total amount) at about 100° C., and crush after cooling to obtain a powder coating.

[0081] The coatings obtained in the above examples and comparative examples were applied to a metal substrate by electrostatic spraying with a coating thickness of 0.2 mm and baked at 150° C. for 40 min to obtain a coating. The obtained coatings were treated under an open flame at 800° C. for 24 h and 240 h, respectively, and their properties were tested. The adhesion was tested with reference to GB / T9286-1998, and the hardness was tested with reference to GB / T 6739 1996. The test results are shown in Table 1 below.

[0082] Table 1 Test results

[0083]

[0084] It can be seen from the above test results that the flame-resistant powder coating of the present invention can still maintain good adhesion and hardness after long-term flame treatment, and the appearance has no cracks or the cracks are not obvious. The components of the coating of the present invention can maintain a relatively dense coating film at high temperature and have long-term fire resistance. However, the formula of Comparative Example 1 does not use polysiloxane, and the formula of Comparative Example 2 does not contain hexaphenoxy cyclotriphosphazene. The performance of the coating is seriously reduced after the flame treatment; Comparative Example 3 uses aromatic diamine, and the flame resistance is reduced.

[0085] 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 modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A flame resistant powder coating, characterized in that The invention comprises the following raw materials in parts by weight: 100 parts of phenolic epoxy resin; 20-30 parts of aromatic triamine; 10-20 parts of amino-terminated polydimethylsiloxane; 10-20 parts of polyphenylmethylsiloxane; Pentaerythritol glycidyl ether 10-15 parts; 5 to 10 parts of hexaphenoxy cyclotriphosphazene; 60-80 parts of inorganic filler.

2. The flame resistant powder coating according to claim 1, characterized in that The invention comprises the following raw materials in parts by weight: 100 parts of phenolic epoxy resin; 25-30 parts of aromatic triamine; 10-15 parts of amino-terminated polydimethylsiloxane; 15-20 parts of polyphenylmethylsiloxane; Pentaerythritol glycidyl ether 10-12 parts; 8-10 parts of hexaphenoxy cyclotriphosphazene; 70-80 parts of inorganic filler.

3. The flame-resistant powder coating according to claim 1 or 2, characterized in that: The inorganic filler includes at least one of flaky aluminum oxide, ceramic powder, and silicon dioxide; The particle size of the flaky aluminum oxide is 3 to 15 μm, the particle size of the ceramic powder is 1 to 20 μm, and the particle size of the silicon dioxide is 1 to 50 μm; Preferably, the inorganic filler is a mixture of flaky aluminum oxide and at least one of ceramic powder and silicon dioxide, and the mass content of the flaky aluminum oxide in the inorganic filler is 20 to 30%.

4. The flame-resistant powder coating according to claim 1 or 2, characterized in that: The weight average molecular weight of the amino-terminated polydimethylsiloxane is 1000 to 1500; The weight average molecular weight of the polyphenylmethylsiloxane is 2500-3000.

5. The flame-resistant powder coating according to claim 1 or 2, characterized in that: The phenolic epoxy resin is at least one of NPCN-702 and NPCN-704; The aromatic triamine is at least one of mesitylenetriamine, 1,3,5-tris(4-aminophenyl)benzene, and N,N',N"-triphenyl-1,3,5-benzenetriamine.

6. The method for preparing the open flame resistant powder coating according to any one of claims 1 to 5, characterized in that The following steps are involved: Step 1: heating and mixing amino-terminated polydimethylsiloxane, polyphenylmethylsiloxane and pentaerythritol glycidyl ether at a first temperature to obtain a first mixture; Step 2: Heat and mix the first mixture, phenolic epoxy resin, aromatic tertiary amine, hexaphenoxy cyclotriphosphazene and inorganic filler at a second temperature, and grind them after cooling to obtain a flame-resistant powder coating.

7. The preparation method according to claim 6, characterized in that: In the step 1, the first temperature is 120-130° C., and the time for heating and mixing uniformly at the first temperature is 10-20 minutes.

8. The preparation method according to claim 6 or 7, characterized in that: In the step 2, the second temperature is 90-100° C., and the time for heating and mixing uniformly at the first temperature is 5-10 minutes.

9. The preparation method according to claim 6, characterized in that: The step 2 is carried out in a twin-screw extruder.

10. A coating, characterized in that The powder coating is formed by heating and curing the flame-resistant powder coating as claimed in any one of claims 1 to 5, or by heating and curing the flame-resistant powder coating obtained by the preparation method as claimed in any one of claims 6 to 9.

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