Polyvinyl chloride powder coating with high adhesive strength and method for preparing the same

Abstract

The application belongs to the technical field of polymer coating and specifically relates to a polyvinyl chloride powder coating with high adhesive strength and a preparation method thereof. The polyvinyl chloride powder coating with high adhesive strength is composed of the following components in mass fraction: polyvinyl chloride resin: 100 parts; organic tin stabilizer: 1-3 parts; plasticizer: 30-40 parts; lubricant: 0.6-0.8 parts; leveling agent 1: 2-3 parts; leveling agent 2: 0.5-0.8 parts; toughening agent: 3-5 parts; ultraviolet absorber: 0.6-0.8 parts; titanium white powder: 1-3 parts; pigment: 0-0.05 parts. The application can not only improve the adhesive property with the surface of a spraying part, the coating layer is not prone to cracks, and the service life of the material is improved, but also has the advantages of simple process, mild and easy-to-control preparation condition, easy enlargement, good stability and facilitation of industrialized production.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer coatings, and particularly relates to a polyvinyl chloride powder coating with high bonding strength and a preparation method thereof. Background Art

[0002] Green and environmentally friendly development is the future direction of the coatings industry. Powder coatings, which contain no organic solvents, are environmentally friendly and pollution-free, and are easy to transport, are current research hotspots and future development directions. Powder coatings can be divided into several types based on their primary ingredients, including polyvinyl chloride powder coatings, polyethylene powder coatings, fluororesin powder coatings, polyester powder coatings, and epoxy resin powder coatings. PVC powder coatings offer excellent flame retardancy and weather resistance, and are relatively affordable, offering cost advantages. They are widely used for protective and decorative coatings on highway guardrails, streetlight poles, shelves, containers, and the interior and exterior surfaces of metal pipes.

[0003] Before spraying PVC powder coating, the surface of the sprayed parts usually needs to be derusted and sprayed with primer to increase the adhesion between the powder coating and the metal.

[0004] Chinese patent CN 108467663A, published on August 31, 2018, discloses a novel method for preparing electroplating-like powder coatings. The method involves spraying a metallic base powder evenly onto the surface of a metal workpiece. After the base powder is completely cured and cooled, a transparent resin powder is evenly sprayed onto the workpiece to enhance the coating's bonding strength. However, polyvinyl chloride powder coatings use small molecule additives such as plasticizers and lubricants. These additives are affected by climate and temperature during use. Thermal expansion and contraction can cause surface cracking and even flaking of the sprayed coating, shortening the product's service life. This is particularly true when used outdoors.

[0005] Chinese patent CN 108727917A, published on November 2, 2018, discloses a sun-resistant automotive powder coating and its preparation method. The coating's sun resistance is improved by mixing a melamine-modified titanium dioxide polyester solution with polyvinyl chloride. However, the complex preparation method makes it unsuitable for industrial production. Summary of the Invention

[0006] The purpose of the present invention is to provide a polyvinyl chloride powder coating with high bonding strength, which can not only improve the bonding performance with the surface of the sprayed part, but also make the coating layer less likely to crack, thereby increasing the service life of the material.

[0007] Another object of the present invention is to provide a method for preparing a polyvinyl chloride powder coating with high bonding strength. The method has a simple process, mild and easily controllable preparation conditions, is easy to scale up, has good stability, and is conducive to industrial production.

[0008] The technical solution adopted by the present invention is:

[0009] The polyvinyl chloride powder coating with high bonding strength is made from the following raw materials in parts by mass:

[0010] Polyvinyl chloride resin: 100 parts; organic tin stabilizer: 1-3 parts; plasticizer: 30-40 parts; lubricant: 0.6-0.8 parts; leveling agent 1: 2-3 parts; leveling agent 2: 0.5-0.8 parts; toughening agent: 3-5 parts; ultraviolet absorber: 0.6-0.8 parts; titanium dioxide: 1-3 parts; pigment: 0-0.05 parts.

[0011] The polyvinyl chloride resin is a suspension-processed loose polyvinyl chloride, and the average polymerization degree of the resin is 400-500.

[0012] The organotin stabilizer is preferably a methyltin mercaptan stabilizer.

[0013] The plasticizer is a compound of dioctyl sebacate and epoxidized soybean oil, and the plasticizer is a compound of dioctyl sebacate and epoxidized soybean oil in a mass ratio of 8:2.

[0014] The lubricant is ethylene bis stearamide (EBS) grafted with polar groups.

[0015] The leveling agent 1 is an acrylate-styrene-acrylonitrile emulsion ternary copolymer resin (ASA).

[0016] The leveling agent 2 is a phosphate, and the phosphate is sodium dihydrogen phosphate.

[0017] The toughening agent is chlorosulfonated polyethylene resin (CSM).

[0018] The ultraviolet absorber is a benzotriazole ultraviolet absorber, the titanium dioxide is rutile titanium dioxide, and the pigment is an organic or inorganic pigment.

[0019] The method for preparing the polyvinyl chloride powder coating with high bonding strength comprises the following steps:

[0020] (1) Compounding of polyvinyl chloride powder coating: Add polyvinyl chloride resin, organic tin stabilizer and other solid additives except toughening agent to a high-speed mixer and mix them at a speed of 1800-2100 rpm. When the mixing temperature reaches 75-85°C, add liquid plasticizer and continue stirring to raise the temperature to 100-110°C. Then add toughening agent, titanium dioxide and pigment and continue stirring to raise the temperature to 115-125°C. Put the materials into a low-speed mixer at a speed of 900-1100 rpm. When the material temperature cools to 38-45°C, discharge the materials.

[0021] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) By improving the components and preparation methods, not only the bonding performance between the polyvinyl chloride powder coating and the sprayed surface is improved, but also the coating layer is not prone to cracking, thereby increasing the service life of the material;

[0024] (2) By adding the leveling agent sodium dihydrogen phosphate, the processing performance of the coating is improved, and the spray coating is prevented from falling off due to rust on the metal surface during use;

[0025] (3) The hydrogen bonding between the two hydrogen atoms in sodium dihydrogen phosphate and the oxygen atoms in the sulfenyl chloride group of the chlorosulfonated polyethylene resin not only produces a cross-linking effect, improving the toughness of the coating, but also greatly enhances the adhesion between the coating and the metal spraying surface, ensuring good processing performance of the coating. DETAILED DESCRIPTION

[0026] The present invention is further described below with reference to the following examples, but they do not limit the implementation of the present invention.

[0027] Raw materials used in the examples:

[0028]

[0029]

[0030] Test method:

[0031] 1. Leveling time test method: Derust a Ø10 iron wire, preheat it in a muffle furnace at 330°C for 1.0 minute, immediately dip it in PVC powder coating for 1.5 seconds, and then quickly place it in a 220°C oven for a leveling test. Use a stopwatch to time the test, and visually observe the time it takes for the PVC powder coating to become flat and smooth on the surface of the sample. This is the leveling time.

[0032] 2. Peel force test method:

[0033] (1) Preparation of polyvinyl chloride powder coating: Add PVC resin, organotin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 2000 rpm. When the mixing temperature reaches 80°C, add liquid plasticizer and continue stirring to raise the temperature to 105°C. Then add CSM resin, titanium dioxide and pigment and continue stirring to raise the temperature to 120°C. Place the material in a low-speed mixer and discharge it when the material temperature cools to 40°C.

[0034] (2) Peeling force test: The polyvinyl chloride powder coating was plasticized into a sheet on a two-roll mill at a temperature of 160°C for 5 minutes. The thickness of the sample was about 0.5 mm. The sheet was then sandwiched between two 0.4 mm thick galvanized iron plates and pressed into a composite metal sheet on a sheet press at a temperature of 180°C for 3 minutes. The pressed sample was cut into strips with a width of 20 mm. The peeling force between the galvanized sheets was tested with reference to GB / T 7122-1996 "Determination of peel strength of high-strength adhesives - Floating roller method"; the peeling test speed was 50 mm / min.

[0035] (3) Aging conditions: The specimens were placed in an aging test chamber at 85°C for 240 h.

[0036] Example 1

[0037] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 2000 rpm. When the mixing temperature reaches 80°C, add liquid plasticizer, continue stirring and heat to 105°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 120°C, put the materials into a low-speed mixer at a speed of 1000 rpm, and discharge the materials when the material temperature cools to 40°C;

[0038] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0039] Example 2

[0040] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 2100 rpm. When the mixing temperature reaches 75°C, add liquid plasticizer, continue stirring and heat to 100°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 115°C, put the materials into a low-speed mixer at a speed of 1100 rpm, and discharge the materials when the material temperature cools to 38°C;

[0041] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0042] Example 3

[0043] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 1900 rpm. When the mixing temperature reaches 85°C, add liquid plasticizer, continue stirring and heat to 110°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 125°C, put the materials into a low-speed mixer at a speed of 1100 rpm, and discharge the materials when the material temperature cools to 45°C;

[0044] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0045] Example 4

[0046] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 1800 rpm. When the mixing temperature reaches 80°C, add liquid plasticizer, continue stirring and heat to 110°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 115°C, put the materials into a low-speed mixer at a speed of 1000 rpm, and discharge the materials when the material temperature cools to 40°C;

[0047] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0048] Example 5

[0049] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 2000 rpm. When the mixing temperature reaches 75°C, add liquid plasticizer, continue stirring and heat to 105°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 120°C, put the materials into a low-speed mixer at a speed of 1100 rpm, and discharge the materials when the material temperature cools to 40°C;

[0050] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0051] Example 6

[0052] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 2100 rpm. When the mixing temperature reaches 80°C, add liquid plasticizer, continue stirring and heat to 105°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 125°C, put the materials into a low-speed mixer at a speed of 1100 rpm, and discharge the materials when the material temperature cools to 45°C;

[0053] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0054] Example 7

[0055] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 1800 rpm. When the mixing temperature reaches 80°C, add liquid plasticizer, continue stirring and heat to 100°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 120°C, put the materials into a low-speed mixer at a speed of 900 rpm, and discharge the materials when the material temperature cools to 38°C;

[0056] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0057] Example 8

[0058] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 2000 rpm. When the mixing temperature reaches 85°C, add liquid plasticizer, continue stirring and heat to 105°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 115°C, put the materials into a low-speed mixer at a speed of 1100 rpm, and discharge the materials when the material temperature cools to 45°C;

[0059] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0060] Example 9

[0061] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 1900 rpm. When the mixing temperature reaches 80°C, add liquid plasticizer, continue stirring and heat to 100°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 125°C, put the materials into a low-speed mixer at a speed of 1000 rpm, and discharge the materials when the material temperature cools to 40°C;

[0062] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0063] Example 10

[0064] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 2000 rpm. When the mixing temperature reaches 85°C, add liquid plasticizer, continue stirring and heat to 100°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 110°C, put the materials into a low-speed mixer at a speed of 1100 rpm, and discharge the materials when the material temperature cools to 40°C;

[0065] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0066] The content of each component in Examples 1-10 is shown in Table 1, and the content is in parts by mass.

[0067] Table 1 Component content of each embodiment

[0068]

[0069]

[0070] Comparative Example 1

[0071] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 2000 rpm. When the mixing temperature reaches 80°C, add liquid plasticizer, continue stirring and heat to 105°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 120°C, put the materials into a low-speed mixer at a speed of 1000 rpm, and discharge the materials when the material temperature cools to 40°C;

[0072] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0073] Comparative Example 2

[0074] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 2000 rpm. When the mixing temperature reaches 75°C, add liquid plasticizer, continue stirring and heat to 100°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 115°C, put the materials into a low-speed mixer at a speed of 1100 rpm, and discharge the materials when the material temperature cools to 38°C;

[0075] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0076] Comparative Example 3

[0077] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 2100 rpm. When the mixing temperature reaches 85°C, add liquid plasticizer, continue stirring and heat to 110°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 125°C, put the materials into a low-speed mixer at a speed of 1000 rpm, and discharge the materials when the material temperature cools to 45°C;

[0078] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0079] Comparative Example 4

[0080] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 2000 rpm. When the mixing temperature reaches 80°C, add liquid plasticizer, continue stirring and heat to 110°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 115°C, put the materials into a low-speed mixer at a speed of 900 rpm, and discharge the materials when the material temperature cools to 40°C;

[0081] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0082] Comparative Example 5

[0083] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 1800 rpm. When the mixing temperature reaches 75°C, add liquid plasticizer, continue stirring and heat to 105°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 120°C, put the materials into a low-speed mixer at a speed of 1000 rpm, and discharge the materials when the material temperature cools to 40°C;

[0084] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0085] Comparative Example 6

[0086] (1) Add PVC resin, organic tin stabilizer and other solid additives (except CSM resin) to a high-speed mixer and mix at a speed of 2000 rpm. When the mixing temperature reaches 80°C, add liquid plasticizer, continue stirring and heat to 105°C, add CSM resin, titanium dioxide and pigment, continue stirring and heat to 125°C, put the materials into a low-speed mixer at a speed of 900 rpm, and discharge the materials when the material temperature cools to 45°C;

[0087] (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

[0088] The content of each component in Comparative Examples 1-6 is shown in Table 2, and the content is in parts by mass.

[0089] Table 2 Component contents of each comparative example

[0090]

[0091]

[0092] The test results of Examples 1-10 are shown in Table 3;

[0093] The test results of Comparative Examples 1-6 are shown in Table 4;

[0094] Table 3 Test results of Examples 1-10

[0095]

[0096]

[0097] Table 4 Test results of comparative examples 1-6

[0098]

[0099] Compared to the examples, Comparative Example 1 used ACR PA-101 as a leveling agent instead of ASA resin, while Comparative Example 2 used polyvinyl chloride paste resin as a leveling agent instead of ASA resin. Comparative Example 3 did not use the toughening agent CSM-40. Comparative Example 4 added the crosslinker DCP instead of sodium dihydrogen phosphate, and Comparative Examples 5-6 used sodium phosphate and sodium dihydrogen phosphate as leveling agents instead of sodium dihydrogen phosphate. The peel strength of the comparative examples was lower than that of the examples, and the performance after aging was also poor.

Claims

1. A polyvinyl chloride powder coating with high bonding strength, characterized in that: It is made of the following raw materials in parts by mass: polyvinyl chloride resin: 100 parts; organic tin stabilizer: 1-3 parts; Plasticizer: 30-40 parts; Lubricant: 0.6-0.8 parts; Leveling agent 1: 2-3 parts; Leveling agent 2: 0.5-0.8 parts; Toughening agent: 3-5 parts; UV absorber: 0.6-0.8 parts; Titanium dioxide: 1-3 parts; Pigment: 0-0.05 parts; The leveling agent 1 is an acrylate-styrene-acrylonitrile emulsion ternary copolymer resin; The leveling agent 2 is sodium dihydrogen phosphate; The toughening agent is chlorosulfonated polyethylene resin CSM.

2. The polyvinyl chloride powder coating with high bonding strength according to claim 1, characterized in that: The polyvinyl chloride resin is a suspension-processed loose polyvinyl chloride, and the average polymerization degree of the resin is 400-500.

3. The polyvinyl chloride powder coating with high bonding strength according to claim 1, characterized in that: The plasticizer is a compound of dioctyl sebacate and epoxidized soybean oil, and the plasticizer is a compound of dioctyl sebacate and epoxidized soybean oil in a mass ratio of 8:

2.

4. The polyvinyl chloride powder coating with high bonding strength according to claim 1, characterized in that: The lubricant is ethylene bisstearamide grafted with polar groups.

5. The polyvinyl chloride powder coating with high bonding strength according to claim 1, characterized in that: The ultraviolet absorber is a benzotriazole ultraviolet absorber, the titanium dioxide is rutile titanium dioxide, and the pigment is an organic or inorganic pigment.

6. A method for preparing a polyvinyl chloride powder coating with high bonding strength according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Compounding of polyvinyl chloride powder coating: Add polyvinyl chloride resin, organic tin stabilizer and other solid additives except toughening agent into high-speed mixer and mix them. When the mixing temperature reaches 75-85℃, add plasticizer and continue stirring to raise the temperature to 100-110℃. Add toughening agent, titanium dioxide and pigment and continue stirring to raise the temperature to 115-125℃. Put the materials into low-speed mixer and discharge the materials when the material temperature cools to 38-45℃. (2) Weighing and packaging: Weigh and package the polyvinyl chloride powder coating.

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