A GMA system super-leveling powder coating for doors and windows

Abstract

A GMA system super-leveling powder coating for doors and windows belongs to the field of powder coating technology. The coating comprises 45-60 parts of carboxyl polyester resin, 14-20 parts of carboxyl acrylic resin, 10-30 parts of hydroxy acrylic resin, 8-10 parts of HAA curing agent, 10-12 parts of leveling agent, 1-3 parts of benzoin, 3-5 parts of wear-resistant agent, 3-5 parts of filler dispersant, 3-5 parts of pigment dispersant, 10-40 parts of glass fiber, 10-35 parts of matting barium, and 5-7 parts of carbon black. The coating is mixed, extruded, ground, and baked to achieve an ultra-fine surface effect, thereby solving the problems of surface roughness, haze, and poor wear resistance and stain resistance in the application of traditional GMA system powder coatings.

Description

Technical Field

[0001] The invention belongs to the technical field of powder coatings, and in particular relates to a GMA system super-leveling powder coating for doors and windows. Background Art

[0002] As an environmentally friendly and highly efficient coating material, GMA-based powder coatings hold a significant position in the door and window coating market due to their lack of organic solvents, high coating efficiency, and excellent coating performance. The GMA system (Glycidyl Methacrylate, GMA) contains reactive epoxy groups that can cross-link with compounds containing functional groups such as carboxyl and phenolic hydroxyl groups to form a stable three-dimensional network structure. This results in excellent weather resistance, high hardness, and mechanical properties. Furthermore, it is VOC-free, complying with environmental requirements.

[0003] Leveling refers to the ability of liquid materials to eliminate surface defects (such as brush marks, bubbles, and ripples) and form a uniform and smooth surface during their flow or coating process. This property has a direct impact on the quality of coatings, inks, adhesives, and certain chemicals during use.

[0004] Common powder coating systems on the market include epoxy systems, polyester / TGIC systems, polyester / HAA curing agent systems, and epoxy-polyester hybrid systems. Compared with these systems, the GMA system performs better in terms of weather resistance, mechanical properties, and environmental friendliness. However, traditional GMA system powder coatings still have some defects in door and window coating applications:

[0005] (1) Surface roughness: Due to the relatively poor fluidity and leveling properties of the GMA system, the surface of the coating tends to become rough and granular after curing, affecting the feel and aesthetics of the coating.

[0006] (2) Haze phenomenon: In the process of increasing the hardness of the coating, the added hardener, additive or filler may migrate to the coating surface during the curing process, forming a haze or whitening phenomenon, which reduces the gloss and decorative effect of the coating.

[0007] (3) Poor wear resistance and stain resistance: The coating surface is easily scratched by friction and is not resistant to dirt and stains, which reduces the service life and appearance quality of the product.

[0008] The above problems limit the promotion and application of traditional GMA system powder coatings in application fields with high requirements for decorativeness and performance. Therefore, this application proposes a GMA system super-leveling powder coating for doors and windows. Summary of the Invention

[0009] The purpose of the present invention is to overcome the deficiencies of the prior art and solve the problems of surface roughness, haze, poor wear resistance and antifouling properties in the application of traditional GMA system powder coatings.

[0010] A GMA system super-leveling powder coating for doors and windows, comprising the following components and the weight proportions of each component:

[0011] 45-60 parts of carboxyl polyester resin;

[0012] 14-20 parts of carboxylic acrylic resin;

[0013] 10-30 parts of hydroxy acrylic acid;

[0014] 8-10 parts of HAA curing agent;

[0015] 10-12 parts of leveling agent;

[0016] 1-3 parts of benzoin;

[0017] 3-5 parts of anti-wear agent;

[0018] 3-5 parts of filler dispersant;

[0019] 3-5 parts of pigment dispersant;

[0020] Glass fiber 10-40 parts;

[0021] 10-35 parts of extinction barium;

[0022] 5-7 parts of carbon black.

[0023] Furthermore, the viscosity of the carboxyl polyester at 200° C. is 4500-6000 mPa.s.

[0024] Furthermore, the preparation method of the GMA system super-leveling powder coating for doors and windows comprises the following steps:

[0025] S1. Raw material pretreatment: mixing carboxyl polyester resin, carboxyl acrylic resin, and hydroxy acrylic resin to improve the mixing uniformity and melt fluidity of the resins;

[0026] S2. Additive mixing: HAA curing agent, leveling agent, benzoin, wear-resistant agent, filler dispersant, pigment dispersant, carbon black, glass fiber, and matting barium are mixed to prepare mixed additive powder;

[0027] S3, high-speed premixing: Mix the pretreated raw materials in a high-speed mixer at 2000 rpm for 3-5 minutes to ensure that all components are fully mixed and avoid agglomeration;

[0028] S4. Twin-screw blending: Using twin-screw blending equipment with dispersing and shearing functions to further homogenize the mixture and improve the dispersion of pigments and fillers;

[0029] S5. Melt extrusion: Set segmented temperature control in the extruder, and the temperature gradually increases from the feeding section to the discharging section;

[0030] S6. Rapid cooling: Use high-efficiency cooling rollers or cooling belts to quickly cool the molten material to room temperature to prevent internal stress in the material due to uneven cooling, which may affect the subsequent grinding effect.

[0031] S7, grinding: using air jet mill to control the powder particle size to 28-30um;

[0032] S8. Screening: Use an ultrasonic vibrating screen to finely screen the ground powder to remove oversized and undersized particles, ensure the uniformity of the powder particle size, and produce a GMA system super-leveling powder coating for doors and windows.

[0033] Furthermore, the segmented temperature control in S5 is as follows: feeding section: 90-100°C, compression section: 100-105°C, metering section: 100-105°C.

[0034] The present invention has the following advantages:

[0035] The modified GMA system powder coating prepared by the present invention adjusts the surface wettability of the coating and the viscosity of the carboxyl group, thereby improving the leveling performance, can quickly eliminate unevenness, make the auxiliary agent particles evenly distributed, reduce haze, and increase hardness. After the coating is cured into a film on the door and window substrate, it can obtain an extremely fine and leveling surface effect, and at the same time has high hardness. Because the surface is extremely fine and the density between molecules is large, it can achieve anti-fingerprint and dirt-resistant effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a photo of the powder coating prepared in Example 1, illustrating the leveling and surface smoothness;

[0037] Figure 2 This is a photograph of the powder coating prepared in Example 2, illustrating the leveling and surface smoothness;

[0038] Figure 3 This is a photograph of the powder coating prepared in Example 3, illustrating the leveling and surface smoothness;

[0039] Figure 4 This is a photo of the powder coating prepared in Comparative Example 1, illustrating the leveling and surface smoothness;

[0040] Figure 5This is a photo of the powder coating prepared in Comparative Example 2, illustrating leveling and surface smoothness;

[0041] Figure 6 This is a photo of the powder coating prepared in Comparative Example 3, illustrating leveling and surface smoothness;

[0042] Figure 7 From top to bottom are comparative photos of the surface smoothness of the coatings coated with the powder coatings prepared in Examples 1-3 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail with reference to the following specific examples.

[0044] Example 1:

[0045] The preparation method of the GMA system super-leveling powder coating for doors and windows in this embodiment is as follows:

[0046] S1. Raw material pretreatment: 45 parts by weight of a carboxyl polyester resin with a viscosity of 4500 mPa.s, 14 parts by weight of a carboxyl acrylic resin, and 10 parts by weight of a hydroxy acrylic resin were sieved and mixed to improve the mixing uniformity and melt fluidity of the resins;

[0047] S2. Additive mixing: 8 parts by weight of HAA curing agent, 10 parts by weight of leveling agent, 1 part by weight of benzoin, 3 parts by weight of wear-resistant agent, 5 parts by weight of filler dispersant, 5 parts by weight of pigment dispersant, 5 parts by weight of carbon black, 10 parts by weight of glass fiber, and 10 parts by weight of matting barium are mixed to prepare a mixed additive powder;

[0048] S3, high-speed premixing: the pretreated raw materials were mixed in a high-speed mixer at a speed of 2000 rpm for 3 minutes to ensure that the components were fully mixed and to avoid agglomeration;

[0049] S4. Twin-screw blending: Using twin-screw blending equipment with dispersing and shearing functions to further homogenize the mixture and improve the dispersion of pigments and fillers;

[0050] S5, melt extrusion: set segmented temperature control in the extruder, and gradually increase the temperature from the feeding section to the discharging section, feeding section: 90 ° C, compression section: 100 ° C, metering section: 105 ° C;

[0051] S6. Rapid cooling: Use high-efficiency cooling rollers or cooling belts to quickly cool the molten material to room temperature to prevent internal stress in the material due to uneven cooling, which may affect the subsequent grinding effect.

[0052] S7, grinding: using air jet mill to control the powder particle size to 28 μm;

[0053] S8. Screening: Use an ultrasonic vibrating screen to finely screen the ground powder to remove oversized and undersized particles to produce a GMA system super-leveling powder coating for doors and windows. After the powder coating is sprayed and cured, the coating properties are measured and shown in Table 7.

[0054] Table 1 Example 1 formula raw materials

[0055]

[0056] Example 2:

[0057] The preparation method of the GMA system super-leveling powder coating for doors and windows in this embodiment is as follows:

[0058] S1. Raw material pretreatment: 50 parts by weight of a carboxyl polyester resin with a viscosity of 5000 mPa.s, 16 parts by weight of a carboxyl acrylic resin, and 20 parts by weight of a hydroxy acrylic resin are sieved and mixed to improve the mixing uniformity and melt fluidity of the resins;

[0059] S2. Additive mixing: 9 parts by weight of HAA curing agent, 11 parts by weight of leveling agent, 2 parts by weight of benzoin, 4 parts by weight of wear-resistant agent, 5 parts by weight of filler dispersant, 5 parts by weight of pigment dispersant, 6 parts by weight of carbon black, 25 parts by weight of glass fiber, and 25 parts by weight of matting barium are mixed to prepare a mixed additive powder;

[0060] S3, high-speed premixing: the pretreated raw materials were mixed in a high-speed mixer at a speed of 2000 rpm for 4 minutes to ensure that the components were fully mixed and to avoid agglomeration;

[0061] S4. Twin-screw blending: Using twin-screw blending equipment with dispersing and shearing functions to further homogenize the mixture and improve the dispersion of pigments and fillers;

[0062] S5, melt extrusion: set segmented temperature control in the extruder, and gradually increase the temperature from the feeding section to the discharging section, feeding section: 95 ° C, compression section: 105 ° C, metering section: 105 ° C;

[0063] S6. Rapid cooling: Use high-efficiency cooling rollers or cooling belts to quickly cool the molten material to room temperature to prevent internal stress in the material due to uneven cooling, which may affect the subsequent grinding effect.

[0064] S7. Grinding: Use air jet mill to control the powder particle size to about 30um.

[0065] S8. Screening: Use an ultrasonic vibrating screen to finely screen the ground powder to remove oversized and undersized particles to produce a GMA system super-leveling powder coating for doors and windows. After the powder coating is sprayed and cured, the coating properties are measured and shown in Table 7.

[0066] Table 2 Example 2 Formula Raw Materials

[0067]

[0068] Example 3:

[0069] The preparation method of the GMA system super-leveling powder coating for doors and windows in this embodiment is as follows:

[0070] S1. Raw material pretreatment: 60 parts by weight of a carboxyl polyester resin with a viscosity of 6000 mPa.s, 19 parts by weight of a carboxyl acrylic resin, and 30 parts by weight of a hydroxy acrylic resin were sieved and mixed to improve the mixing uniformity and melt fluidity of the resins;

[0071] S2. Additive mixing: 10 parts by weight of HAA curing agent, 12 parts by weight of leveling agent, 3 parts by weight of benzoin, 5 parts by weight of wear-resistant agent, 5 parts by weight of filler dispersant, 5 parts by weight of pigment dispersant, 7 parts by weight of carbon black, 40 parts by weight of glass fiber, and 35 parts by weight of matting barium are mixed to prepare a mixed additive powder;

[0072] S3, high-speed premixing: the pretreated raw materials were mixed in a high-speed mixer at a speed of 2000 rpm for 5 minutes to ensure that the components were fully mixed and to avoid agglomeration;

[0073] S4. Twin-screw blending: Using twin-screw blending equipment with dispersing and shearing functions to further homogenize the mixture and improve the dispersion of pigments and fillers;

[0074] S5, melt extrusion: set segmented temperature control in the extruder, and gradually increase the temperature from the feeding section to the discharging section, feeding section: 100 ° C, compression section: 1050 ° C, metering section: 105 ° C;

[0075] S6. Rapid cooling: Use high-efficiency cooling rollers or cooling belts to quickly cool the molten material to room temperature to prevent internal stress in the material due to uneven cooling, which may affect the subsequent grinding effect.

[0076] S7, grinding: using air jet mill to control the powder particle size to about 30um;

[0077] S8. Screening: Use an ultrasonic vibrating screen to finely screen the ground powder to remove oversized and undersized particles to produce a GMA system super-leveling powder coating for doors and windows. After the powder coating is sprayed and cured, the coating properties are measured and shown in Table 7.

[0078] Table 3 Example 3 formula raw materials

[0079]

[0080] Comparative Example 1 (Traditional GMA System)

[0081] Table 4 Comparative Example 1 Formula Raw Materials

[0082]

[0083] The preparation was carried out according to the traditional process of the GMA system.

[0084] Comparative Example 2 (Traditional GMA System)

[0085] Table 5 Comparative Example 2 Formula Raw Materials

[0086]

[0087] The preparation was carried out according to the traditional process of the GMA system.

[0088] Comparative Example 3 (Polyester / TGIC System):

[0089] Table 6 Comparative Example 3 Formula Raw Materials

[0090]

[0091] The preparation is carried out according to the traditional process of polyester / TGIC system.

[0092] Performance Testing

[0093] Sample preparation: According to the formulations and processes of Examples 1-3 and Comparative Examples 1-3 above, six powder coating samples were prepared for performance testing;

[0094] Spraying conditions: Use the same electrostatic spraying equipment and parameters, the substrate is pre-treated cold-rolled steel plate for doors and windows, the electrostatic voltage is 70V, the distance between the spray gun and the substrate is 15-20cm, the ambient temperature is 23℃, the relative humidity is 55%, and the layer thickness is 70μm;

[0095] Curing conditions: 190-210°C, curing for 15 minutes. The results are shown in Table 7.

[0096] Table 7 Product performance comparison table 1

[0097]

[0098] Notes: Glossiness: The higher the value, the better the glossiness; Hardness: Pencil hardness, the higher the value, the higher the hardness; Abrasion resistance: The smaller the wear depth, the better the abrasion resistance; Stain resistance: The higher the value, the better the stain resistance; Adhesion: Cross-hatch test, 0 is the best and 5 is the worst; PCI leveling grade refers to the leveling grade of the coating to be tested determined by visually comparing the coating to be tested with a PCI leveling grade reference plate (grades 1-10, specifically a test standard plate from ACT Company is used in this example), which is a common leveling grade determination method in the industry;

[0099] Based on the above experimental data and comparative analysis, the embodiments of the present invention are superior to traditional GMA systems (Comparative Examples 1 and 2) in terms of gloss, leveling, hardness, abrasion resistance, stain resistance, weather resistance, and chemical resistance. The surface wetting of the coating and the adjustment of the viscosity of the carboxyl group improve the leveling performance of the product, solving the problems of uneven leveling of traditional GMA system door and window coatings, which can lead to uneven microstructure after curing and increase haze, and poor leveling, which can lead to uneven distribution of hardener, matting agent, and auxiliary agent particles and increase haze. Compared with the polyester / TGIC system (Comparative Example 3), the embodiments of the present invention avoid the toxicity of TGIC while maintaining high gloss and excellent leveling, and have better environmental performance.

Claims

1. A GMA system super-leveling powder coating for doors and windows, characterized by: The composition comprises the following components in parts by weight: 45-60 parts of carboxyl polyester resin; 14-20 parts of carboxylic acrylic resin; 10-30 parts of hydroxy acrylic resin; 8-10 parts of HAA curing agent; 10-12 parts of leveling agent; 1-3 parts of benzoin; 3-5 parts of anti-wear agent; 3-5 parts of filler dispersant; 3-5 parts of pigment dispersant; Glass fiber 10-40 parts; 10-35 parts of extinction barium; 5-7 parts of carbon black; The viscosity of the carboxyl polyester resin at 200° C. is 4500-6000 mPa.s.

2. The method for preparing the GMA system super-leveling powder coating for doors and windows according to claim 1, characterized in that: The following steps are involved: S1. Raw material pretreatment: mixing carboxyl polyester resin, carboxyl acrylic resin, and hydroxy acrylic resin to prepare pretreated raw materials; S2. Additive mixing: HAA curing agent, leveling agent, benzoin, wear-resistant agent, filler dispersant, pigment dispersant, carbon black, glass fiber, and matting barium are mixed to prepare mixed additive powder; S3, high-speed premixing: the pretreated raw materials and mixing aid powder prepared in S1 and S2 are mixed in a high-speed mixer at a speed of 2000 rpm for 3-5 minutes; S4, twin-screw blending: A twin-screw blending device with dispersing and shearing functions is used to further homogenize the mixture mixed in S3; S5, melt extrusion: the raw material obtained in S4 is fed into an extruder for melt extrusion, and a segmented temperature control is set in the extruder, and the temperature is gradually increased from the feeding section to the discharging section; S6, rapid cooling: Use high-efficiency cooling rollers or cooling belts to quickly cool the molten material obtained in S5 to room temperature to prevent the material from generating internal stress due to uneven cooling, which affects the subsequent grinding effect; S7, grinding: Grind the material after cooling in S6 with a jet mill to control the powder particle size to 28-30 microns; S8. Screening: Use an ultrasonic vibrating screen to finely screen the powder ground in S7 to remove oversized and undersized particles, thereby producing a GMA system super-leveling powder coating for doors and windows.

3. The method for preparing the GMA system super-leveling powder coating for doors and windows according to claim 2, characterized in that: The segmented temperature control in S5 is as follows: feeding section: 90-100°C, compression section: 100-105°C, metering section: 100-105°C.

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