Powder coating with excellent weather resistance as well as preparation method and application of powder coating

Abstract

The invention discloses a powder coating with excellent weather resistance as well as a preparation method and application thereof, and relates to the field of coatings. The powder coating comprises polyester resin, modified nuclear titanium dioxide, a curing agent, a flatting agent, a defoaming agent, wax and filler. The preparation method of the modified nuclear titanium dioxide comprises the following steps: mixing and stirring nuclear titanium dioxide, dioctyl phthalate and octadecanoic acid, and cooling to obtain the modified nuclear titanium dioxide. The dioctyl phthalate and the octadecanoic acid are adopted to modify the nuclear titanium dioxide, so that the weather resistance of the nuclear titanium dioxide is improved under the condition that the gloss is not improved in the matte powder, and the probability that organic matters around the nuclear titanium dioxide of the powder coating are degraded due to the influence of illumination or temperature is effectively reduced, so that the cost is saved.

Description

Technical Field

[0001] The invention relates to the field of powder coatings, and in particular to a powder coating with excellent weather resistance and a preparation method and application thereof. Background Art

[0002] In the coatings industry, weather resistance refers to the ability of coatings to withstand a series of aging phenomena such as fading, discoloration, cracking, powdering and strength loss caused by external conditions such as sunlight, temperature changes, wind and rain. Titanium dioxide is an excellent white pigment in coatings. It has excellent whiteness, hiding power and weather resistance, and is the basis for the development of high-performance coatings.

[0003] A small amount of titanium dioxide in the coating can easily degrade the surrounding organic matter under sunlight and ultraviolet rays, and easily cause loss of gloss, yellowing, powdering and other phenomena, resulting in poor weather resistance and seriously affecting its application performance. Adding a sufficient amount of ordinary titanium dioxide can improve the weather resistance of the coating. When applied to the matte powder field, the UVA lamp can reach the national standard Class I aging resistance of outdoor aluminum profiles for 1000 hours. However, a sufficient amount of titanium dioxide in the coating has the problem of high gloss, resulting in excess performance and waste of raw materials. Summary of the invention

[0004] The present invention provides a powder coating with excellent weather resistance, a preparation method and an application thereof, so as to solve the technical problem that conventional titanium dioxide is used in the current matte powder coating, resulting in high gloss or insufficient weather resistance. By adding modified nuclear titanium dioxide, which has a matting effect in the matte powder, it plays a positive role in the outdoor matte powder, thereby improving the weather resistance of the powder coating, and at the same time reducing the gloss of the coating film and reducing excess performance.

[0005] In order to solve the above technical problems, one of the purposes of the present invention is to provide a powder coating with excellent weather resistance, comprising the following raw materials in parts by weight:

[0006] Polyester resin: 500-600 parts;

[0007] Organically coated nuclear titanium dioxide: 180-230 parts;

[0008] Curing agent: 38-48 parts;

[0009] Leveling agent: 6-13 parts;

[0010] Defoaming agent: 1-6 parts;

[0011] Wax: 3-7 parts;

[0012] Filler: 150-200 parts;

[0013] The method for preparing the organically coated nuclear titanium dioxide comprises the following steps: putting the nuclear titanium dioxide into a dispersing device, dispersing for 10-15 minutes, adding dioctyl phthalate and octadecanoic acid in sequence at a temperature of 100-120°C and stirring, wherein the mass ratio of the nuclear titanium dioxide, dioctyl phthalate and octadecanoic acid is 100:(1-2):(2-3), and cooling to obtain the organically coated nuclear titanium dioxide.

[0014] By adopting the above-mentioned technical scheme, the present application pre-modifies the nuclear titanium dioxide with dioctyl phthalate and octadecanoic acid to improve the weather resistance of the nuclear titanium dioxide itself. When added to the powder coating, the probability of degradation of organic matter around the nuclear titanium dioxide due to light or temperature is effectively reduced. The powder coating can withstand high temperature environment and strong light, resist erosion by natural environmental factors, and improve the overall weather resistance of the powder coating by combining the interaction of waxes in the coating. Since the present application only needs to add a small amount of nuclear titanium dioxide to make the powder coating have lower gloss and higher weather resistance, the required amount of nuclear titanium dioxide can be reduced, and the nuclear titanium dioxide has a matte finish, which effectively reduces the gloss and saves costs.

[0015] As a preferred embodiment, the curing agent is triglycidyl isocyanurate and / or isophorone diisocyanate.

[0016] As a preferred embodiment, the leveling agent is at least one of polyacrylate, GLP leveling agent and LA leveling agent.

[0017] As a preferred embodiment, the defoaming agent is benzoin.

[0018] As a preferred embodiment, the wax is polyethylene wax and / or polytetrafluoroethylene wax.

[0019] As a preferred embodiment, the filler is at least one of barium sulfate, barite powder, quartz powder, silica, kaolin, calcium carbonate, mica powder and white carbon black.

[0020] As a preferred embodiment, the curing agent is triglycidyl isocyanurate, the leveling agent is polyacrylate, the wax is polyethylene wax, and the filler is barium sulfate.

[0021] By adopting the above scheme, polyester, triglycidyl isocyanurate, polyacrylate, benzoin, polyethylene wax and barium sulfate are added to the powder coating together, which helps to provide good internal and external lubrication, improve the fluidity of fillers and nuclear titanium dioxide in the polyester resin system, improve the quality of processed products, and itself can help the polyester resin resist surface discoloration caused by ultraviolet rays or temperature, and improve the overall weather resistance of the powder coating.

[0022] As a preferred solution, the polyester resin is at least one of SJ4E, GH-1155 and NH-3005.

[0023] As a preferred solution, the leveling agent is at least one of PV-88, GLP-588, and TROY-486.

[0024] As a preferred embodiment, the defoaming agent is at least one of Surfynol MD-20, TROY-542DG, and P803.

[0025] As a preferred embodiment, the wax is at least one of BYK-531, PE-520, and TF-1778C.

[0026] As a preferred solution, the filler is at least one of LY-A, AY-JB53, and VENATOR Sachtleben.

[0027] In order to solve the above technical problems, the second object of the present invention is to provide a method for preparing a powder coating with excellent weather resistance, comprising the following steps:

[0028] (1) adding raw materials into a mixing device and mixing them thoroughly to obtain a mixture;

[0029] (2) pouring the mixed material into an extrusion device for extrusion molding into a sheet, and extruding to obtain a sheet material;

[0030] (3) Grinding the flaky material into uniform powder particles, sieving, and obtaining a powder coating.

[0031] As a preferred embodiment, in step (1), the stirring rate is 300-600 rpm and the stirring time is 3-10 min.

[0032] As a preferred embodiment, in step (2), the feed rate of the extruder is 25-50 Hz, the temperature of zone 1 is 90-120°C, the temperature of zone 2 is 90-120°C, the temperature of zone 3 is 90-120°C, the twin screw speed is 30-50 Hz, and the cooling water temperature is 15-35°C.

[0033] As a preferred embodiment, in step (3), the flake material is ground into uniform powder particles at 150-220 mesh, the main grinding parameter is set to 18-30 Hz, the secondary grinding parameter is set to 40-50 Hz, and the sieve mesh number is 150-220 mesh.

[0034] In order to solve the above technical problems, the third object of the present invention is to provide an application of a powder coating with excellent weather resistance in the field of preparing matte powder.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present application uses dioctyl phthalate and octadecanoic acid to modify nuclear titanium dioxide, thereby improving the weather resistance of nuclear titanium dioxide itself, and improving the weather resistance of nuclear titanium dioxide itself without increasing the gloss in matte powder, effectively reducing the probability of organic matter around the nuclear titanium dioxide of powder coating being degraded due to light or temperature, reducing the required amount of nuclear titanium dioxide added, and thus saving costs. DETAILED DESCRIPTION

[0037] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Table 1 - Sources of raw materials in the examples and comparative examples of this application

[0039]

[0040]

[0041] Example 1

[0042] A powder coating with excellent weather resistance, comprising 560kg polyester resin A, 200kg organically coated nuclear titanium dioxide, 42kg curing agent A, 10kg leveling agent A, 3kg defoaming agent A, 5kg wax A and 180kg filler A. In the present embodiment, the polyester resin A is specifically model SJ4E produced by Anhui Shenjian New Materials Co., Ltd., the curing agent A can be triglycidyl isocyanurate, specifically model TGIC-G produced by Niutang Chemical (Binzhou) Co., Ltd., the leveling agent A can be polyacrylate, specifically model PV-88 of the Estelon brand, the defoaming agent A is model Surfynol MD-20 of the Sangjing Chemical brand, the wax A can be polyethylene wax, specifically non-ionic oxidized polyethylene wax of the German BYK brand model BYK-531, and the filler A is barium sulfate, specifically model LY-A of the Yuanlei brand.

[0043] The method for preparing the above-mentioned powder coating with excellent weather resistance comprises the following steps:

[0044] (1) Dispersing and coating in proportion, the mass ratio of nuclear titanium dioxide, dioctyl phthalate and octadecanoic acid is 100:1:2; putting the nuclear titanium dioxide into a high-speed dispersing kettle and dispersing for 15 minutes, raising the temperature to 120° C., adding dioctyl phthalate and octadecanoic acid in turn, and continuing to disperse for 10 minutes, and finally stirring and cooling to 55° C. to obtain organically coated nuclear titanium dioxide, wherein the nuclear titanium dioxide is specifically model RTR-201 sold by Foshan Jianfa Ruitong Technology Co., Ltd.;

[0045] (2) Weigh each raw material using an electronic scale with an accuracy of 0.001 g, add it into a mixing barrel and mix it thoroughly at a stirring rate of 300 rpm for 5 min to obtain a mixture;

[0046] (3) pouring the mixed material into an extruder for extrusion molding into a sheet, the feed rate is 30 Hz, the temperature of the first zone is 100° C., the temperature of the second zone is 110° C., the temperature of the third zone is 100° C., the twin screw speed is 45 Hz, the cooling water temperature is 22° C., and a sheet material is extruded;

[0047] (4) Grinding the flake material to 200 meshes to obtain uniform powder particles, and then sieving the material. The main grinding parameters are set to 23 Hz, the auxiliary grinding parameters are set to 50 Hz, and the sieve mesh number is 200 meshes to obtain a powder coating.

[0048] Example 2

[0049] A powder coating with excellent weather resistance, wherein the steps of the preparation method thereof and the reagents, equipment and process parameters used in the steps are the same as those in Example 1, except that the powder coating comprises 500 kg of polyester resin B, 180 kg of organically coated nuclear titanium dioxide, 38 kg of curing agent B, 6 kg of leveling agent B, 1 kg of defoaming agent B, 3 kg of wax B and 150 kg of filler B. In the present embodiment, the polyester resin B is specifically model GH-1155 of Zhejiang Guanghua Technology Co., Ltd., the curing agent B can be triglycidyl isocyanurate, specifically model HT-702 of acoma brand, the leveling agent B can be polyacrylate, specifically model GLP-588 of Nanhai Chemical brand, the defoaming agent B is model TROY-542DG of TROY brand, the wax B can be low-density polyethylene wax, specifically low-density polyethylene wax of Clariant Licowax brand model PE-520, and the filler B can be barium sulfate, specifically model AY-JB53 of Lianzhuang brand.

[0050] Example 3

[0051] A powder coating with excellent weather resistance, wherein the steps of the preparation method thereof and the reagents, equipment and process parameters used in the steps are the same as those in Example 1, except that the powder coating comprises 600 kg of polyester resin C, 230 kg of organically coated nuclear titanium dioxide, 48 kg of curing agent C, 13 kg of leveling agent C, 6 kg of defoaming agent C, 7 kg of wax C and 200 kg of filler C. In the present embodiment, the polyester resin C is specifically the model NH-3005 of Qingtian Materials Technology Co., Ltd., the curing agent C can be isophorone diisocyanate, specifically the model B1530 of Evonik brand, the leveling agent C can be polyacrylate, specifically the model TROY-486 of TROY brand, the defoaming agent C is the model P803 of Mingling Chemical brand, the wax C can be polytetrafluoroethylene wax, specifically the model TF-1778C of Lubrizol LANCO brand, and the filler C can be precipitated barium sulfate, specifically the model VENATOR Sachtleben of Pannengtuo brand.

[0052] Comparative Example 1

[0053] A powder coating with excellent weather resistance, wherein the steps of the preparation method and the reagents, equipment and process parameters used in the steps are the same as those in Example 1, except that in step (1), the nuclear titanium dioxide is replaced by titanium dioxide A in an equal amount, and titanium dioxide A is specifically model R-219 of the China Nuclear Titanium Dioxide brand.

[0054] Comparative Example 2

[0055] A powder coating with excellent weather resistance, wherein the steps of the preparation method and the reagents, equipment and process parameters used in the steps are the same as those in Example 2, except that in step (1), the core titanium dioxide is replaced by an equal amount of titanium dioxide B, and titanium dioxide B is specifically ATR-312 of the Anada brand.

[0056] Comparative Example 3

[0057] A powder coating with excellent weather resistance, wherein the steps of the preparation method and the reagents, equipment and process parameters used in the steps are the same as those in Example 3, except that in step (1), the core titanium dioxide is replaced by an equal amount of titanium dioxide C, and the specific titanium dioxide C is model R-6618 (T) of Lubei Chemical.

[0058] Comparative Example 4

[0059] A powder coating with excellent weather resistance, wherein the steps of the preparation method and the reagents, equipment and process parameters used in the steps are the same as those in Example 1, except that in step (2), the organically coated nuclear titanium dioxide is replaced by an equal amount of nuclear titanium dioxide, and the nuclear titanium dioxide is specifically model RTR-201 sold by Foshan Jianfa Ruitong Technology Co., Ltd.

[0060] Comparative Example 5

[0061] A powder coating with excellent weather resistance, wherein the steps of the preparation method and the reagents, equipment and process parameters used in the steps are the same as those in Example 3, except that in step (1), nuclear titanium dioxide is put into a high-speed dispersing kettle and dispersed for 15 minutes, the temperature is raised to 120°C, γ-aminopropyltriethoxysilane is added and stirred, the mass ratio of nuclear titanium dioxide to γ-aminopropyltriethoxysilane is 100:3, and the dispersion is continued for 10 minutes, and finally the mixture is stirred and cooled to 55°C, wherein the nuclear titanium dioxide is specifically model RTR-201 sold by Foshan Jianfa Ruitong Technology Co., Ltd., and the organically coated nuclear titanium dioxide is obtained after cooling.

[0062] Comparative Example 6

[0063] A powder coating with excellent weather resistance, wherein each step of the preparation method and the reagents, equipment and process parameters used in each step are the same as those in Example 3, except that the addition amount of wax A is 0.

[0064] Performance testing

[0065] The sieved powder coating of the above embodiment or comparative example is sprayed on an aluminum plate with a spray gun, and the sprayed sample is placed in an oven for curing, and baked at 200°C for 10 minutes. The baked and cured sample is subjected to the following corresponding tests:

[0066] 1. The specific gravity of the powder coatings of the examples or comparative examples was tested according to ISO787-10 standard. The test results are shown in Table 2 below.

[0067] 2. The impact resistance of the spray-coated sample of the embodiment or comparative example was tested according to the paint film impact resistance determination method of GB / T1732-2020, and the test result showed that it passed.

[0068] 3. According to GB / T5237.4-2017 standard, the adhesion and boiling color difference ΔE of the sprayed sample of the embodiment or comparative example at 100°C for 2h were tested. The test results are shown in Table 2 below.

[0069] 4. The bending taper of the embodiment or comparative example was tested according to the GB / T11185-2009 paint and varnish bending test (conical axis) standard. The test results are shown in Table 2 below.

[0070] 5. The cupping of the sprayed samples of the embodiment and the comparative example was tested according to the cupping test standard of paint and varnish GB / T9753-2007. The test results are shown in Table 2 below.

[0071] 6. The aging resistance test of the embodiment or comparative example spray-coated sample was carried out according to cycle A of method 1 in the national standard for grade I aging resistance GB / T 1865-2009. The test was carried out for 1000 hours. The gloss retention rate was measured according to GB / T 9754, and the color difference was measured according to GB / T 11186.2. The test results are shown in Table 2 below.

[0072] 7. The glossiness of the spray-coated sample of the embodiment or comparative example was tested according to GB / T 9754-2007 standard at an angle of 65 degrees. The test results are shown in Table 2 below.

[0073] Table 2 - Performance test results of powder coatings prepared in the present application examples and comparative examples

[0074]

[0075]

[0076] As shown in Table 2, titanium dioxide is added to the powder coatings of Comparative Examples 1-3 of the present application. Since the whiteness of titanium dioxide is too high when added to the powder coating, there is excess performance, and the weather resistance of titanium dioxide is limited, the gloss retention rate after 1000h aging test is significantly reduced and the color difference is significantly increased. In the powder coatings of Examples 1-3 of the present application, modified core titanium dioxide is added. The core titanium dioxide has a certain matting effect, so the gloss in the powder coating, especially the matte powder, will be lower than that of the added titanium dioxide, and the weather resistance of the modified core titanium dioxide is improved, so that the coating formed in Examples 1-3 has a higher gloss retention rate after 1000h aging test than that of Comparative Examples 1-3, and the color difference is lower than that of Comparative Examples 1-3, and has excellent weather resistance.

[0077] As shown in Table 2, compared with Comparative Example 4, Example 1 uses dioctyl phthalate and octadecanoic acid to encapsulate and modify the nuclear titanium dioxide, which effectively improves the weather resistance of the nuclear titanium dioxide itself. When added to the powder coating, it effectively reduces the probability of degradation of organic matter around the nuclear titanium dioxide of the powder coating due to light or temperature, reduces the required amount of nuclear titanium dioxide added, reduces the whiteness of the powder coating, and saves costs.

[0078] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A powder coating having excellent weather resistance, characterized in that: It includes the following raw materials in parts by weight: Polyester resin: 500-600 parts; Organically coated nuclear titanium dioxide: 180-230 parts; Curing agent: 38-48 parts; Leveling agent: 6-13 parts; Defoaming agent: 1-6 parts; Wax: 3-7 parts; Filler: 150-200 parts; Among them, the preparation method of the organically coated nuclear titanium dioxide includes the following steps: putting the nuclear titanium dioxide into a dispersing device, dispersing for 10-15 minutes, adding dioctyl phthalate and octadecanoic acid in sequence at a temperature of 100-120°C and stirring and dispersing, wherein the mass ratio of the nuclear titanium dioxide, dioctyl phthalate and octadecanoic acid is 100:(1-2):(2-3), and obtaining the organically coated nuclear titanium dioxide after cooling.

2. A powder coating with excellent weather resistance as claimed in claim 1, characterized in that: The curing agent is triglycidyl isocyanurate and / or isophorone diisocyanate.

3. A powder coating with excellent weather resistance as claimed in claim 1, characterized in that: The leveling agent is at least one of a polyacrylate leveling agent, a GLP leveling agent, and a LA leveling agent.

4. A powder coating with excellent weather resistance as claimed in claim 1, characterized in that: The defoaming agent is benzoin.

5. A powder coating with excellent weather resistance as claimed in claim 1, characterized in that: The wax is polyethylene wax and / or polytetrafluoroethylene wax.

6. A powder coating with excellent weather resistance as claimed in claim 1, characterized in that: The filler is at least one of barium sulfate, barite powder, quartz powder, silica, kaolin, calcium carbonate, mica powder and white carbon black.

7. A powder coating with excellent weather resistance as claimed in claim 1, characterized in that: The curing agent is triglycidyl isocyanurate, the leveling agent is polyacrylate, the wax is polyethylene wax, and the filler is barium sulfate.

8. A method for preparing a powder coating having excellent weather resistance as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: (1) adding raw materials into a mixing device and mixing them thoroughly to obtain a mixture; (2) pouring the mixed material into an extrusion device for extrusion molding into a sheet, and extruding to obtain a sheet material; (3) Grinding the flaky material into uniform powder particles, sieving, and obtaining a powder coating.

9. The method for preparing a powder coating having excellent weather resistance according to claim 8, characterized in that: Satisfy at least one of the following a)-c): a) in step (1), the stirring rate is 300-600 rpm and the time is 3-10 min; b) In step (2), the feed rate of the extruder is 25-50 Hz, the temperature of zone 1 is 90-120°C, the temperature of zone 2 is 90-120°C, the temperature of zone 3 is 90-120°C, the speed of the twin screw is 30-50 Hz, and the cooling water temperature is 15-35°C; c) In step (3), the flake material is ground into uniform powder particles at 150-220 mesh, the main grinding parameter is set to 18-30 Hz, the auxiliary grinding parameter is set to 40-50 Hz, and the sieve mesh number is 150-220 mesh.

10. Use of the powder coating with excellent weather resistance as claimed in any one of claims 1 to 7 in the field of preparing matte powder.

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