GMA system super-leveling powder coating for doors and windows

Abstract

The invention discloses a GMA system super-leveling powder coating for doors and windows, and belongs to the technical field of powder coatings. Comprising 45-60 parts of carboxyl polyester resin, 14-20 parts of carboxyl acrylic resin, 10-30 parts of hydroxyl acrylic resin, 8-10 parts of an HAA curing agent, 10-12 parts of a flatting agent, 1-3 parts of benzoin, 3-5 parts of a wear-resistant agent, 3-5 parts of a filler dispersing agent, 3-5 parts of a pigment dispersing agent, 10-40 parts of glass fibers, 10-35 parts of extinction barium sulfate and 5-7 parts of carbon black. The superfine surface effect is obtained through mixing, extruding, grinding and baking. The problems of rough surface, fog shadow phenomenon and poor wear resistance and pollution resistance existing in the application of the traditional GMA system powder coating are solved.

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 efficient coating material, GMA system powder coating occupies an important position in the door and window coating market due to its characteristics of no organic solvents, high coating efficiency, and excellent coating performance. The GMA system (Glycidyl Methacrylate, referred to as GMA) contains active epoxy groups, which can undergo cross-linking reactions with compounds containing functional groups such as carboxyl and phenolic hydroxyl groups to form a stable three-dimensional network structure. Therefore, it has excellent weather resistance, high hardness and mechanical properties. At the same time, it does not contain volatile organic compounds (VOC) and meets environmental protection 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. Common powder coating systems on the market include epoxy system, polyester / TGIC system, polyester / HAA curing agent system and epoxy-polyester hybrid system. Compared with these systems, GMA system performs better in weather resistance, mechanical properties and environmental protection. However, traditional GMA system powder coatings still have some defects in the application of door and window coatings: (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, which affects the feel and aesthetics of the coating.

[0004] (2) Haze phenomenon: In the process of improving 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.

[0005] (3) Poor wear resistance and stain resistance: The coating surface is easily scratched by friction and is not resistant to dirt and stains are easily left, which reduces the service life and appearance quality of the product.

[0006] 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, the present application proposes a GMA system super-leveling powder coating for doors and windows. Summary of the invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and solve the problems of surface roughness, haze phenomenon, poor wear resistance and antifouling properties in the application of traditional GMA system powder coatings.

[0008] A GMA system super-leveling powder coating for doors and windows, comprising the following components and the weight proportions of each component: 45-60 parts of carboxyl polyester resin; 14-20 parts of carboxylic acrylic resin; 10-30 parts of hydroxy acrylic acid; 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; Extinction barium 10-35 parts; Carbon black 5-7 parts.

[0009] Furthermore, the viscosity of the carboxyl polyester at 200° C. is 4500-6000 mPa.s.

[0010] Furthermore, the preparation method of the GMA system super-leveling powder coating for doors and windows comprises the following steps: 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; 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 obtain mixed additive powder; S3, high-speed premixing: Mix the pretreated raw materials in a high-speed mixer at a speed of 2000 rpm for 3-5 minutes to ensure that the components are fully mixed and avoid agglomeration; S4, Twin-screw blending: Use twin-screw blending equipment with dispersing and shearing functions to further homogenize the mixture and improve the dispersibility of pigments and fillers; S5, melt extrusion: set segmented temperature control in the extruder, and the temperature gradually increases 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 to room temperature to prevent the material from generating internal stress due to uneven cooling, which will affect the subsequent grinding effect; S7, grinding: using jet mill, the powder particle size is controlled at 28-30um; S8. Screening: Use an ultrasonic vibration 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.

[0011] 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.

[0012] The present invention has the following advantages: The modified GMA system powder coating prepared by the present invention adjusts the surface wetting of the coating and the viscosity of the carboxyl group to improve the leveling performance, can quickly eliminate unevenness, make the auxiliary agent particles evenly distributed, reduce haze, and increase hardness at the same time. After the coating is cured into a film on the door and window substrate, an extremely fine and leveling effect can be obtained, and at the same time, it has high hardness. Because the surface is extremely fine and the density between molecules is large, it can achieve the effects of anti-fingerprint and anti-fouling. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a photo of the powder coating prepared in Example 1, which illustrates the leveling and surface flatness; Figure 2 This is a photo of the powder coating prepared in Example 2, illustrating the leveling and surface flatness; Figure 3 This is a photo of the powder coating prepared in Example 3, illustrating the leveling and surface flatness; Figure 4 This is a photo of the powder coating prepared in Comparative Example 1, which illustrates the leveling and surface flatness; Figure 5 This is a photo of the powder coating prepared in Comparative Example 2, which illustrates the leveling and surface flatness; Figure 6 This is a photo of the powder coating prepared in Comparative Example 3, which illustrates the leveling and surface flatness; Figure 7 From top to bottom are comparison photos of the surface flatness of the coatings coated with powder coatings prepared in Examples 1-3 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0014] The present invention will be further described in detail with reference to the following specific embodiments.

[0015] Embodiment 1: The preparation method of the GMA system super-leveling powder coating for doors and windows in this embodiment is as follows: S1, raw material pretreatment: 45 parts by weight of carboxyl polyester resin with a viscosity of 4500 mPa.s, 14 parts by weight of carboxyl acrylic resin, and 10 parts by weight of hydroxy acrylic resin are sieved and mixed to improve the mixing uniformity and melt fluidity of the resins; 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 matte barium are mixed to prepare a mixed additive powder; S3, high-speed premixing: the pretreated raw materials are mixed in a high-speed mixer at a speed of 2000 rpm for 3 minutes to ensure that the components are fully mixed and agglomeration is avoided; S4, Twin-screw blending: Use twin-screw blending equipment with dispersing and shearing functions to further homogenize the mixture and improve the dispersibility of pigments and fillers; S5, melt extrusion: set segmented temperature control in the extruder, and the temperature gradually increases from the feeding section to the discharging section, feeding section: 90°C, compression section: 100°C, metering section: 105°C; S6. Rapid cooling: Use high-efficiency cooling rollers or cooling belts to quickly cool the molten material to room temperature to prevent the material from generating internal stress due to uneven cooling, which will affect the subsequent grinding effect; S7, grinding: using jet mill to control the powder particle size to 28um; S8. Screening: Use an ultrasonic vibration 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.

[0016] Table 1 Example 1 Formula Raw Materials Table Embodiment 2: The preparation method of the GMA system super-leveling powder coating for doors and windows in this embodiment is as follows: 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; 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 matte barium are mixed to prepare a mixed additive powder; S3, high-speed premixing: the pretreated raw materials are mixed in a high-speed mixer at a speed of 2000 rpm for 4 minutes to ensure that the components are fully mixed and agglomeration is avoided; S4, Twin-screw blending: Use twin-screw blending equipment with dispersing and shearing functions to further homogenize the mixture and improve the dispersibility of pigments and fillers; S5, melt extrusion: set segmented temperature control in the extruder, and the temperature gradually increases from the feeding section to the discharging section, feeding section: 95°C, compression section: 105°C, metering section: 105°C; S6. Rapid cooling: Use high-efficiency cooling rollers or cooling belts to quickly cool the molten material to room temperature to prevent the material from generating internal stress due to uneven cooling, which will affect the subsequent grinding effect; S7. Grinding: Use air jet mill to control the powder particle size to about 30um.

[0017] S8. Screening: Use an ultrasonic vibration 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.

[0018] Table 2 Example 2 Formula Raw Materials Table Embodiment 3: The preparation method of the GMA system super-leveling powder coating for doors and windows in this embodiment is as follows: S1, raw material pretreatment: 60 parts by weight of carboxyl polyester resin with a viscosity of 6000 mPa.s, 19 parts by weight of carboxyl acrylic resin, and 30 parts by weight of hydroxy acrylic resin are sieved and mixed to improve the mixing uniformity and melt fluidity of the resins; 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 matte barium are mixed to prepare a mixed additive powder; S3, high-speed premixing: the pretreated raw materials are mixed in a high-speed mixer at a speed of 2000 rpm for 5 minutes to ensure that the components are fully mixed and agglomeration is avoided; S4, Twin-screw blending: Use twin-screw blending equipment with dispersing and shearing functions to further homogenize the mixture and improve the dispersibility of pigments and fillers; S5, melt extrusion: set segmented temperature control in the extruder, and the temperature gradually increases from the feeding section to the discharging section, feeding section: 100°C, compression section: 1050°C, metering section: 105°C; S6. Rapid cooling: Use high-efficiency cooling rollers or cooling belts to quickly cool the molten material to room temperature to prevent the material from generating internal stress due to uneven cooling, which will affect the subsequent grinding effect; S7, grinding: using jet mill to control the powder particle size to about 30um; S8. Screening: Use an ultrasonic vibration 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.

[0019] Table 3 Example 3 Formula Raw Materials Table Comparative Example 1 (Traditional GMA System) Table 4 Comparative Example 1 Formula Raw Materials The preparation was carried out according to the traditional process of the GMA system.

[0020] Comparative Example 2 (Traditional GMA System) Table 5 Comparative Example 2 Formula Raw Materials The preparation was carried out according to the traditional process of the GMA system.

[0021] Comparative Example 3 (Polyester / TGIC System): Table 6 Comparative Example 3 Formula Raw Materials The preparation is carried out according to the traditional process of polyester / TGIC system.

[0022] Performance Testing Sample preparation: According to the formulations and processes of the above Examples 1-3 and Comparative Examples 1-3, six powder coating samples were prepared for performance testing; Spraying conditions: the same electrostatic spraying equipment and parameters were used uniformly, the substrate was pre-treated cold-rolled steel plate for doors and windows, the electrostatic voltage was 70V, the distance between the spray gun and the substrate was 15-20cm, the ambient temperature was 23℃, the relative humidity was 55%, and the layer thickness was 70μm; Curing conditions: 190-210°C, curing for 15 minutes. The results are shown in Table 7.

[0023] Table 7 Product performance comparison table 1 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; Antifouling: the higher the value, the better the antifouling; Adhesion: cross-hatch test, 0 is the best, 5 is the worst; PCI leveling grade specifically refers to visually comparing the coating to be tested with the PCI leveling grade control plate (1-10, this embodiment specifically uses the test standard plate from ACT Company) to determine the leveling grade corresponding to the coating to be tested, which is a common leveling grade determination method in the industry; Through the above experimental data and comparative analysis, the embodiments of the present invention are superior to the traditional GMA system (Comparative Examples 1 and 2) in terms of gloss, leveling, hardness, wear 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, and solve the problems that the uneven leveling of the traditional GMA system door and window coating will lead to uneven microstructure after curing and increase haze, and poor leveling will 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 problem of TGIC while maintaining high gloss and excellent leveling, and have better environmental protection performance.

Claims

1. A GMA system super-leveling powder coating for doors and windows, characterized in that: 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; Extinction barium 10-35 parts; Carbon black 5-7 parts.

2. The GMA system super-leveling powder coating for doors and windows according to claim 1, characterized in that: The viscosity of the carboxyl polyester resin at 200° C. is 4500-6000 mPa.s.

3. The method for preparing the GMA system super-leveling powder coating for doors and windows according to any one of claims 1-2, characterized in that: The following steps are involved: S1, raw material pretreatment: carboxyl polyester resin, carboxyl acrylic resin, and hydroxy acrylic resin are mixed to obtain a pretreated raw material; 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 obtain mixed additive powder; S3, high-speed premixing: the pretreated raw materials and mixing auxiliary powders 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 will affect the subsequent grinding effect; S7, grinding: grinding the material after cooling in S6 by using a jet mill, and controlling the powder particle size to 28-30um; S8, screening: Use an ultrasonic vibration screen to finely screen the powder ground in S7 to remove oversized and undersized particles, and obtain a GMA system super-leveling powder coating for doors and windows.

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

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