Coil textured powder coating and its preparation method and application

Abstract

The present invention belongs to the field of coating technology, and particularly relates to a coiled material textured powder coating, and its preparation method and application. A coiled material textured powder coating comprises a modified hydroxyl-terminated polyester resin, a curing agent, and an auxiliary agent; the auxiliary agent comprises a toughening agent, and the toughening agent is polyamide; the modified hydroxyl-terminated polyester resin is obtained by modifying the hydroxyl-terminated polyester resin with hydroxyl-terminated polybutadiene. The present invention uses hydroxyl-terminated polybutadiene to modify the polyester resin, thereby increasing the reaction speed between the modified hydroxyl-terminated polyester resin, the curing agent, and the toughening agent, shortening the curing time. The three act together to enable the coating to cure quickly and have good storage stability. The formed coating has a clear texture, good bending performance, good acid and alkali resistance, good solvent resistance, and scratch resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and in particular relates to a coiled textured powder coating and a preparation method and application thereof. Background Art

[0002] Powder coatings and their application technology have been rapidly developing in recent years, offering advantages such as resource conservation, reduced environmental pollution, and 100% coating utilization. Currently, the thermal curing process for common textured powder coatings on the market is a slow, energy-intensive bake-out process at 200°C for 10-20 minutes. The resulting coatings are thick, with poor adhesion, salt spray resistance, storage stability, impact resistance, and bending properties, completely failing to meet the performance requirements of textured powder coatings for coil applications.

[0003] Some studies have solved the problem of air permeability in coatings by adding a combination of breathable agents and floating agents, but this is mainly used for SUV bumpers with complex structures and is not suitable for coils with more post-processing requirements. Another study has produced a crocodile-patterned reticulated powder coating with a strong three-dimensional effect and a strong touch, but the coating has a curing time of 200°C / 15 minutes, and it does not focus on bending resistance, which cannot meet the requirements of rapid curing and bending resistance of the coil. In addition, ordinary reticulated powder coatings must first be fully melted and leveled before reacting with a floating agent to produce texture, while coil reticulated powder coatings have an extremely short curing time (230-280°C / 60-90s). It is extremely difficult to complete the melting and production of textured powder in coils within 90 seconds. At the same time, coil powder coatings have very high requirements for bending performance, but the surface of the reticulated powder coating itself is uneven, with a surface effect of "ridges" and "valleys", and the bending effect is poor.

[0004] Therefore, there is an urgent need to provide a coiled material textured powder coating that can be quickly cured and has clear textured lines and good bending performance. Summary of the Invention

[0005] The present invention aims to solve one or more technical problems existing in the prior art and at least provide a beneficial alternative or create conditions. The present invention provides a coiled material textured powder coating that can be quickly cured and the resulting coating has clear textures and good bending performance.

[0006] The present invention's concept is as follows: The textured powder coating for coils comprises a modified hydroxyl-terminated polyester resin, a curing agent, and an additive, wherein the additive includes a toughening agent; the toughening agent is a polyamide; and the modified hydroxyl-terminated polyester resin is obtained by modifying a hydroxyl-terminated polyester resin with hydroxyl-terminated polybutadiene. The present invention utilizes hydroxyl-terminated polybutadiene to modify the polyester resin, thereby increasing the reaction rate among the modified hydroxyl-terminated polyester resin, the curing agent, and the toughening agent and shortening the curing time. The combined effect of these three factors allows for rapid curing of the coating, resulting in a coating with clear texture and excellent bending properties.

[0007] Therefore, a first aspect of the present invention provides a coil textured powder coating.

[0008] Specifically, a coiled textured powder coating includes a modified hydroxyl-terminated polyester resin, a curing agent, and an additive;

[0009] The auxiliary agent includes a toughening agent; the toughening agent is polyamide;

[0010] The modified hydroxyl-terminated polyester resin is obtained by modifying the hydroxyl-terminated polyester resin by using hydroxyl-terminated polybutadiene.

[0011] Preferably, the powder coating comprises, by weight, 40-90 parts of modified hydroxyl-terminated polyester resin, 1-10 parts of curing agent, and 1-20 parts of auxiliary agent.

[0012] Preferably, the powder coating comprises 60-80 parts of modified hydroxyl-terminated polyester resin, 3-8 parts of curing agent, and 1-12 parts of auxiliary agent in parts by weight.

[0013] Preferably, the powder coating further comprises at least one of a filler and a pigment.

[0014] Preferably, the powder coating comprises fillers and pigments; and by weight, the powder coating comprises 40-90 parts of modified hydroxyl-terminated polyester resin, 1-10 parts of curing agent, 1-20 parts of auxiliary agent, 0.5-50 parts of filler, and 0.5-15 parts of pigment.

[0015] Further preferably, the powder coating comprises, by weight, 60-80 parts of modified hydroxyl-terminated polyester resin, 3-8 parts of curing agent, 1-12 parts of auxiliary agent, 5-30 parts of filler, and 1-8 parts of pigment.

[0016] Preferably, the hydroxyl value of the modified hydroxyl-terminated polyester resin is 40-100 mgKOH / g; more preferably, the hydroxyl value of the modified hydroxyl-terminated polyester resin is 50-80 mgKOH / g.

[0017] Preferably, the ICI melt viscosity of the modified hydroxyl-terminated polyester resin at 200° C. is 3000-7000 mPa·s; further preferably, the ICI melt viscosity of the modified hydroxyl-terminated polyester resin at 200° C. is 3500-5500 mPa·s.

[0018] Preferably, the raw materials for preparing the modified hydroxyl-terminated polyester resin include polyol, polyacid, acidolysis agent, and hydroxyl-terminated polybutadiene.

[0019] Preferably, the raw materials for preparing the modified hydroxyl-terminated polyester resin include, by weight, 22-55 parts of polyol, 13-40 parts of polyacid, 4.5-22 parts of acidolysis agent, and 0.9-17 parts of hydroxyl-terminated polybutadiene.

[0020] Further preferably, the raw materials for preparing the modified hydroxyl-terminated polyester resin include, by weight, 25-50 parts of polyol, 15-35 parts of polyacid, 5-20 parts of acidolysis agent, and 1-15 parts of hydroxyl-terminated polybutadiene.

[0021] Preferably, the raw materials for preparing the modified hydroxyl-terminated polyester resin further include auxiliary agents.

[0022] Preferably, the raw materials for preparing the modified hydroxyl-terminated polyester resin include, by weight, 22-55 parts of polyol, 13-40 parts of polyacid, 4.5-22 parts of acidolysis agent, 0.9-17 parts of hydroxyl-terminated polybutadiene, and 0.9-5.5 parts of auxiliary agent.

[0023] Further preferably, the raw materials for preparing the modified hydroxyl-terminated polyester resin include, by weight, 25-50 parts of polyol, 15-35 parts of polyacid, 5-20 parts of acidolysis agent, 1-15 parts of hydroxyl-terminated polybutadiene, and 1-5 parts of auxiliary agent.

[0024] Preferably, the polyol includes at least one of neopentyl glycol, ethylene glycol, 1,3-propylene glycol, trimethylolpropane, ethylbutylpropylene glycol, trimethylpentanediol, and 1,6-hexanediol.

[0025] Preferably, the polyacid includes at least one of terephthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, and trimellitic anhydride.

[0026] Preferably, the acidolysis agent includes at least one of isophthalic acid, adipic acid, trimellitic anhydride, and sebacic acid.

[0027] Preferably, the auxiliary agent is selected from at least one of the esterification catalysts monobutyltin oxide and dibutyltin dilaurate.

[0028] Preferably, the curing agent includes at least one of tetramethoxymethyl glycoluril resin, blocked isocyanate, triglycidyl isocyanurate, and hydroxyalkylamide.

[0029] More preferably, the curing agent is tetramethoxymethyl glycoluril.

[0030] Preferably, the filler includes at least one of precipitated barium, calcium carbonate, and mica powder.

[0031] Preferably, the pigment is at least one of general-purpose outdoor pigments; further preferably, the pigment is selected from at least one of rutile titanium dioxide and red iron oxide.

[0032] Preferably, the additives of the powder coating further include at least one of a leveling agent, a degassing agent, wax powder, a curing accelerator, and a texture additive.

[0033] Preferably, the leveling agent is an acrylic polymer.

[0034] Preferably, the degassing agent is selected from at least one of benzoin, polypropylene wax and stearic acid.

[0035] Preferably, the wax powder is selected from at least one of polytetrafluoroethylene wax and polyethylene wax.

[0036] Preferably, the curing accelerator is selected from at least one of 2-methylimidazole, quaternary ammonium salt, dimethyl laurylamine, butyltriphenylphosphonium bromide, and amine-blocked sulfonic acid accelerator.

[0037] More preferably, the curing accelerator is selected from at least one of dimethyl laurylamine and amine-blocked sulfonic acid accelerator.

[0038] Preferably, the reticulated texture aid is selected from at least one of styrene maleic anhydride copolymer and o-cresol formaldehyde epoxy resin.

[0039] Preferably, the D50 particle size of the powder coating is 20-45 μm; further preferably, the D50 particle size of the powder coating is 35-45 μm.

[0040] The second aspect of the present invention provides a method for preparing the coil textured powder coating according to the first aspect of the present invention.

[0041] Specifically, the method for preparing the coiled textured powder coating comprises the following steps:

[0042] The raw material components are mixed, extruded and powdered to obtain the coiled textured powder coating.

[0043] Preferably, the extrusion is performed using a twin-screw extruder; the temperature of zone I of the twin-screw extruder is 90-110°C, and the temperature of zone II is 95-110°C.

[0044] Further preferably, the temperature of zone I of the twin-screw extruder is 95-105°C, and the temperature of zone II is 100-105°C.

[0045] Preferably, the preparation method of the modified hydroxyl-terminated polyester resin comprises the following steps:

[0046] (1) mixing a polyol and a polyacid, reacting them, and obtaining an esterification product;

[0047] (2) mixing the esterification product obtained in step (1) with hydroxyl-terminated polybutadiene, and reacting them to obtain a hydroxyl-terminated polyester resin;

[0048] (3) mixing the terminal hydroxy polyester resin obtained in step (2) with an acidolysis agent, reacting and polycondensing to obtain the modified terminal hydroxy polyester resin.

[0049] Specifically, the reaction in step (1) is an esterification reaction.

[0050] Preferably, in step (1), an auxiliary agent is added when the polyol and the polyacid are mixed.

[0051] Preferably, in step (1), the reaction temperature is 180-270° C., and the reaction time is 2.5-5.5 h; further preferably, the reaction temperature is 200-250° C., and the reaction time is 3-5 h.

[0052] Preferably, in step (2), the reaction temperature is 160-250° C., and the reaction time is 0.5-3.5 h; further preferably, the reaction temperature is 180-230° C., and the reaction time is 1-3 h.

[0053] Preferably, in step (3), the reaction temperature is 180-260° C., and the reaction time is 1.5-5.5 h; further preferably, the reaction temperature is 200-240° C., and the reaction time is 2-5 h.

[0054] Preferably, in step (3), the polycondensation is vacuum polycondensation.

[0055] Preferably, the pressure of the vacuum polycondensation is less than 300 Pa; further preferably, the pressure of the vacuum polycondensation is greater than 100 Pa and less than 300 Pa.

[0056] A third aspect of the present invention provides a coiled material.

[0057] Specifically, the coil includes a coating formed by the coil textured powder coating described in the first aspect of the present invention.

[0058] Preferably, the coiled material is a galvanized sheet coil.

[0059] Preferably, the thickness of the coating is 45-110 μm; further preferably, the thickness of the coating is 50-100 μm.

[0060] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0061] (1) The coiled material textured powder coating of the present invention comprises a modified hydroxyl-terminated polyester resin, a curing agent, and an auxiliary agent, wherein the auxiliary agent comprises a toughening agent, and the toughening agent is a polyamide; and the modified hydroxyl-terminated polyester resin is obtained by modifying a polyester resin with hydroxyl-terminated polybutadiene. By modifying the polyester resin with hydroxyl-terminated polybutadiene, the reaction speed among the modified hydroxyl-terminated polyester resin, the curing agent, and the toughening agent is increased, and the curing time is shortened. The three together make the coating have good storage stability and can be cured quickly. The formed coating has clear texture, good acid and alkali resistance, and good bending performance, and the bending performance of the coating can reach 0T.

[0062] (2) Hydroxyl-terminated polybutadiene is a linear polymer with good flexibility and a long main chain. In the process of synthesizing resins, it replaces part of the polyol or polyacid through condensation reaction to synthesize a polyester resin with a "soft segment" in the main chain, namely a modified hydroxyl-terminated polyester resin. This block copolymerization method improves the toughening effect through chemical reaction blending. After the block is cured and cross-linked, it still forms a two-phase system with an island structure. Hydroxyl-terminated polybutadiene is dispersed in the matrix resin in the form of particles. When subjected to external force, it consumes a large amount of external energy by generating shear bands, hindering crack propagation and dissipating stress. In addition, when used with a polyamide toughening agent, the coating has excellent flexibility and post-processing bending performance, and the bending performance of the coating reaches 0T.

[0063] (3) The degassing agent and wax powder in the additive of the present invention ensure the removal of small molecules during the curing process and the final appearance of the coating texture, while also improving the scratch resistance of the coating.

[0064] (4) The preparation process of the present invention is simple and convenient for large-scale production and application. DETAILED DESCRIPTION

[0065] In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the following examples are given for illustration. It should be noted that the following examples do not limit the scope of protection claimed by the present invention.

[0066] Unless otherwise specified, the raw materials, reagents, or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0067] The raw material components and amounts of the powder coatings of Examples 1-5 and Comparative Examples 1-3 of the present invention are shown in Table 1.

[0068] Table 1: Raw material components and amounts of powder coatings of Examples 1-5 and Comparative Examples 1-3

[0069]

[0070] In Table 1, “—” means no addition.

[0071] Example 1

[0072] A coiled textured powder coating comprises, by weight, the raw material components and amounts listed in Table 1.

[0073] A method for preparing a coiled textured powder coating comprises the following steps:

[0074] (1) placing each raw material component in a mixing tank, mixing and crushing it thoroughly to obtain a mixed material;

[0075] (2) melt-kneading the mixture obtained in step (1) by a twin-screw extruder, uniformly dispersing and extruding, wherein the temperature of zone I of the twin-screw extruder is 95° C. and the temperature of zone II is 100° C., and then tableting, cooling, and crushing by a tablet press, and then pulverizing by a grinder and sieving to obtain a coiled textured powder coating with a D50 particle size of 25-45 μm.

[0076] The preparation method of the modified hydroxyl-terminated polyester resin comprises the following steps:

[0077] (1) 25 parts of ethylene glycol, 15 parts of terephthalic acid and 1 part of monobutyltin oxide were mixed and subjected to esterification reaction under nitrogen protection at a temperature of 200°C for a reaction time of 5 hours to obtain an esterified product with a hydroxyl value of 20-40 mgKOH / g;

[0078] (2) mixing the esterification product obtained in step (1) with 1 part of hydroxyl-terminated polybutadiene to react at a reaction temperature of 180° C. for a reaction time of 3 h to obtain a hydroxyl-terminated polyester resin;

[0079] (3) The hydroxyl-terminated polyester resin obtained in step (2) was mixed with 5 parts of isophthalic acid to undergo acid hydrolysis reaction at a reaction temperature of 200° C. for 4 hours to obtain an acid hydrolysis product having a hydroxyl value of 50-80 mgKOH / g. The acid hydrolysis product was subjected to vacuum polycondensation (pressure of 200 Pa) to obtain a modified hydroxyl-terminated polyester resin.

[0080] Example 2

[0081] A coiled textured powder coating comprises, by weight, the raw material components and amounts listed in Table 1.

[0082] A method for preparing a coiled textured powder coating comprises the following steps:

[0083] (1) placing each raw material component in a mixing tank, mixing and crushing it thoroughly to obtain a mixed material;

[0084] (2) melt-kneading the mixture obtained in step (1) by a twin-screw extruder, uniformly dispersing and extruding, wherein the temperature of zone I of the twin-screw extruder is 100° C. and the temperature of zone II is 105° C., and then tableting, cooling, and crushing by a tablet press, and then pulverizing by a pulverizer and sieving to obtain a coiled textured powder coating with a D50 particle size of 25-45 μm.

[0085] The preparation method of the modified hydroxyl-terminated polyester resin comprises the following steps:

[0086] (1) 30 parts of neopentyl glycol, 20 parts of isophthalic acid and 2 parts of dibutyltin dilaurate were mixed and subjected to esterification reaction under nitrogen protection at a temperature of 220° C. for 4 hours to obtain an esterified product with a hydroxyl value of 20-40 mgKOH / g;

[0087] (2) mixing the esterification product obtained in step (1) with 6 parts of hydroxyl-terminated polybutadiene, reacting the mixture at a temperature of 200° C. for 2 h to obtain a hydroxyl-terminated polyester resin;

[0088] (3) The hydroxyl-terminated polyester resin obtained in step (2) was mixed with 8 parts of adipic acid for acid hydrolysis reaction at a reaction temperature of 220° C. for a reaction time of 3.5 h to obtain an acid hydrolysis product having a hydroxyl value of 50-80 mgKOH / g. The acid hydrolysis product was subjected to vacuum polycondensation (pressure of 200 Pa) to obtain a modified hydroxyl-terminated polyester resin.

[0089] Example 3

[0090] A coiled textured powder coating comprises, by weight, the raw material components and amounts listed in Table 1.

[0091] A method for preparing a coiled textured powder coating comprises the following steps:

[0092] (1) placing each raw material component in a mixing tank, mixing and crushing it thoroughly to obtain a mixed material;

[0093] (2) The mixture obtained in step (1) is melt-kneaded by a twin-screw extruder, uniformly dispersed and extruded, wherein the temperature of zone I of the twin-screw extruder is 105° C. and the temperature of zone II is 105° C., and then the mixture is tableted, cooled, and crushed by a tablet press, and then pulverized by a pulverizer and sieved to obtain a coiled textured powder coating with a D50 particle size of 25-45 μm.

[0094] The preparation method of the modified hydroxyl-terminated polyester resin comprises the following steps:

[0095] (1) 40 parts of 1,3-propylene glycol, 25 parts of succinic acid and 4 parts of dibutyltin dilaurate were mixed and subjected to esterification reaction under nitrogen protection at a temperature of 240° C. for 3 hours to obtain an esterified product having a hydroxyl value of 20-40 mgKOH / g;

[0096] (2) mixing the esterification product obtained in step (1) with 10 parts of hydroxyl-terminated polybutadiene, the reaction temperature is 230° C., the reaction time is 1 hour, and a hydroxyl-terminated polyester resin is obtained;

[0097] (3) The hydroxyl-terminated polyester resin obtained in step (2) was mixed with 12 parts of trimellitic anhydride for acid hydrolysis reaction at a reaction temperature of 240° C. for a reaction time of 3 h to obtain an acid hydrolysis product having a hydroxyl value of 50-80 mgKOH / g. The acid hydrolysis product was subjected to vacuum polycondensation (pressure of 200 Pa) to obtain a modified hydroxyl-terminated polyester resin.

[0098] Example 4

[0099] A coiled textured powder coating comprises, by weight, the raw material components and amounts listed in Table 1.

[0100] A method for preparing a coiled textured powder coating comprises the following steps:

[0101] (1) placing each raw material component in a mixing tank, mixing and crushing it thoroughly to obtain a mixed material;

[0102] (2) melt-kneading the mixture obtained in step (1) by a twin-screw extruder, uniformly dispersing and extruding, wherein the temperature of zone I of the twin-screw extruder is 95° C. and the temperature of zone II is 100° C., and then tableting, cooling, and crushing by a tablet press, and then pulverizing by a grinder and sieving to obtain a coiled textured powder coating with a D50 particle size of 25-45 μm.

[0103] The preparation method of the modified hydroxyl-terminated polyester resin comprises the following steps:

[0104] (1) 45 parts of ethyl butyl propylene glycol, 30 parts of adipic acid and 4 parts of monobutyl tin oxide were mixed and subjected to esterification reaction under nitrogen protection at a temperature of 220° C. for a reaction time of 4 h to obtain an esterified product having a hydroxyl value of 20-40 mgKOH / g;

[0105] (2) mixing the esterification product obtained in step (1) with 10 parts of hydroxyl-terminated polybutadiene, reacting the mixture at a temperature of 200° C. for 2 h to obtain a hydroxyl-terminated polyester resin;

[0106] (3) The hydroxyl-terminated polyester resin obtained in step (2) was mixed with 15 parts of sebacic acid for acid hydrolysis reaction at a reaction temperature of 220° C. for a reaction time of 4 h to obtain an acid hydrolysis product having a hydroxyl value of 50-80 mgKOH / g. The acid hydrolysis product was subjected to vacuum polycondensation (pressure of 200 Pa) to obtain a modified hydroxyl-terminated polyester resin.

[0107] Example 5

[0108] A coiled textured powder coating comprises, by weight, the raw material components and amounts listed in Table 1.

[0109] A method for preparing a coiled textured powder coating comprises the following steps:

[0110] (1) placing each raw material component in a mixing tank, mixing and crushing it thoroughly to obtain a mixed material;

[0111] (2) melt-kneading the mixture obtained in step (1) by a twin-screw extruder, uniformly dispersing and extruding, wherein the temperature of zone I of the twin-screw extruder is 100° C. and the temperature of zone II is 100° C., and then tableting, cooling, and crushing by a tablet press, and then pulverizing by a pulverizer and sieving to obtain a coiled textured powder coating with a D50 particle size of 25-45 μm.

[0112] The preparation method of the modified hydroxyl-terminated polyester resin comprises the following steps:

[0113] (1) 50 parts of trimethylpentanediol, 35 parts of terephthalic acid and 5 parts of dibutyltin dilaurate were mixed and subjected to esterification reaction under nitrogen protection at a temperature of 250° C. for a reaction time of 3 h to obtain an esterified product having a hydroxyl value of 20-40 mgKOH / g;

[0114] (2) mixing the esterification product obtained in step (1) with 15 parts of hydroxyl-terminated polybutadiene, the reaction temperature is 230° C., the reaction time is 3 h, and a hydroxyl-terminated polyester resin is obtained;

[0115] (3) The hydroxyl-terminated polyester resin obtained in step (2) was mixed with 20 parts of isophthalic acid to undergo acid hydrolysis reaction at a reaction temperature of 240° C. for a reaction time of 2 h to obtain an acid hydrolysis product having a hydroxyl value of 50-80 mgKOH / g. The acid hydrolysis product was subjected to vacuum polycondensation (pressure of 200 Pa) to obtain a modified hydroxyl-terminated polyester resin.

[0116] Comparative Example 1

[0117] The only difference between Comparative Example 1 and Example 2 is that Comparative Example 1 uses an equal amount of ordinary hydroxyl-terminated polyester resin NH7805 with a hydroxyl value of 30-50 mgKOH / g (Qingtian Material Technology Co., Ltd.) to replace the modified hydroxyl-terminated polyester resin, and the rest is the same as Example 2.

[0118] Comparative Example 2

[0119] The only difference between Comparative Example 2 and Example 2 is that Comparative Example 2 uses an equal amount of styrene-butadiene rubber modified hydroxyl-terminated polyester resin to replace the modified hydroxyl-terminated polyester resin, and the rest is the same as Example 2.

[0120] Comparative Example 3

[0121] The only difference between Comparative Example 3 and Example 2 is that Comparative Example 3 uses an equal amount of chlorinated polyethylene to replace polyamide, and the rest is the same as Example 2.

[0122] Performance Testing

[0123] The powder coatings prepared in Examples 1-5 and Comparative Examples 1-3 were applied to galvanized sheets using a one-coat-one-over process and cured (the curing temperature for Examples 1-5 and Comparative Examples 2-3 was 250° C., and the curing time was as shown in Table 1; the curing temperature for Comparative Example 1 was 190° C., and the curing time was as shown in Table 1) to obtain a coating with a thickness of 70 μm. The coatings were then subjected to relevant tests. The test items and test methods are as follows:

[0124] Gloss: tested according to GB / T 9754-2007;

[0125] Pencil hardness: tested according to GB / T 6739-2006;

[0126] Impact performance: tested according to GB / T 1732-2020;

[0127] 2000h xenon lamp aging test: tested according to GB / T13448-2019;

[0128] Solvent resistance (MEK): tested according to GB / T13448-2019;

[0129] T-bend performance: tested according to GB / T13448-2019;

[0130] Acid and alkali resistance: tested according to GB 9274-1988;

[0131] Appearance: Evaluated by visual inspection.

[0132] The test results of each test item are shown in Table 2.

[0133] Table 2: Performance test results of powder coatings of Examples 1-5 and Comparative Examples 1-3

[0134]

[0135]

[0136] From the results in Table 3, it can be seen that the coiled textured powder coating of the present invention can be quickly cured and has good storage stability. The formed coating has clear texture, good bending performance, good acid and alkali resistance, good solvent resistance, and scratch resistance.

[0137] Comparative Example 1 uses a conventional hydroxyl-terminated polyester resin as the main film-forming component, resulting in a long curing time, poor storage stability, poor flexural properties, low hardness, and poor scratch resistance, making it unsuitable for use in textured coil powder coatings. In contrast, Example 2 uses a modified hydroxyl-terminated polyester resin, which increases the coating's reaction speed and significantly shortens the curing time, enabling the stable generation of textured lines. The use of a texture enhancement agent and a leveling agent ensures a coating with an appropriately sized texture and a strong three-dimensional effect. Furthermore, the coating exhibits excellent storage stability, good bending properties, and excellent acid and alkali resistance, solvent resistance, and scratch resistance.

[0138] Comparative Example 2 uses styrene-butadiene rubber modified polyester resin to replace the terminal hydroxyl polybutadiene modified polyester resin, resulting in poorer bending performance than Example 2.

[0139] Comparative Example 3 uses an equal amount of chlorinated polyethylene to replace polyamide, resulting in a bending performance worse than that of Example 2, indicating that the combined effect of the polyamide toughening agent, curing agent and modified hydroxyl-terminated polyester resin can make the coating have better bending performance.

[0140] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A powder coating, characterized in that: The invention comprises, by weight, 40-90 parts of modified hydroxyl-terminated polyester resin, 1-10 parts of curing agent, and 1-20 parts of auxiliary agent; the auxiliary agent comprises a toughening agent; the toughening agent is polyamide; The modified hydroxyl-terminated polyester resin is obtained by modifying the hydroxyl-terminated polyester resin with hydroxyl-terminated polybutadiene; The modified hydroxyl-terminated polyester resin has a hydroxyl value of 40-100 mgKOH / g; The curing agent is tetramethoxymethyl glycoluril resin; The auxiliary agent further comprises a curing accelerator, and the curing accelerator is an amine-blocked sulfonic acid accelerator.

2. The powder coating according to claim 1, characterized in that The powder coating further comprises at least one of a filler and a pigment.

3. The powder coating according to claim 1, characterized in that The raw materials for preparing the modified hydroxyl-terminated polyester resin include polyol, polyacid, acidolysis agent and hydroxyl-terminated polybutadiene.

4. The powder coating according to claim 3, characterized in that The polyol includes at least one of neopentyl glycol, ethylene glycol, 1,3-propylene glycol, trimethylolpropane, ethyl butyl propanediol, trimethylpentanediol, and 1,6-hexanediol; the polyacid includes at least one of terephthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, and trimellitic anhydride; and the acidolysis agent includes at least one of isophthalic acid, adipic acid, trimellitic anhydride, and sebacic acid.

5. The method for preparing a powder coating according to any one of claims 1 to 4, characterized in that: The following steps are involved: The powder coating is prepared by mixing the raw material components, extruding and powdering.

6. The preparation method according to claim 5, characterized in that The extrusion is carried out using a twin-screw extruder; the temperature of zone I of the twin-screw extruder is 90-110°C, and the temperature of zone II is 95-110°C.

7. The preparation method according to claim 5, characterized in that The preparation method of the modified hydroxyl-terminated polyester resin comprises the following steps: (1) mixing a polyol and a polyacid, reacting them, and obtaining an esterification product; (2) mixing the esterification product obtained in step (1) with hydroxyl-terminated polybutadiene, and reacting them to obtain a hydroxyl-terminated polyester resin; (3) mixing the terminal hydroxy polyester resin obtained in step (2) with an acidolysis agent, reacting and polycondensing to obtain the modified terminal hydroxy polyester resin.

8. The preparation method according to claim 7, characterized in that In step (1), the reaction temperature is 180-270° C., and the reaction time is 2.5-5.5 h; And / or, in step (2), the reaction temperature is 160-250° C., and the reaction time is 0.5-3.5 h; And / or, in step (3), the reaction temperature is 180-260° C., and the reaction time is 1.5-5.5 h.

9. A coiled material, characterized in that: A coating formed by the powder coating according to any one of claims 1 to 4.

Images