A powder coating for high adhesion and high hardness on electrophoretic substrates

Abstract

The present application belongs to the technical field of electrostatic powder coating, and particularly relates to a powder coating with high adhesion and high hardness on electrophoresis base material. The powder coating is composed of the following components in parts by weight: epoxy resin, 55-65 parts by weight; hydroxyl acrylic resin, 30-40 parts by weight; polyvinylidene fluoride, 5-10 parts by weight; isocyanurate, 5-6 parts by weight; polyamide, 5-6 parts by weight; bismuth oxide / porous hydroxyapatite / titanium dioxide composite, 20-30 parts by weight; mullite doped zirconia composite, 8-15 parts by weight; polyvinyl alcohol short fiber, 0.5-2 parts by weight; pigment, 2-4 parts by weight. The powder coating with high adhesion and high hardness on electrophoresis base material has high adhesion, high hardness, corrosion resistance and weather resistance.

Description

Technical Field

[0001] This invention belongs to the field of electrostatic powder coating technology, specifically relating to a powder coating with high adhesion and high hardness applicable to electrophoretic substrates. Background Technology

[0002] Electrostatic powder coating is a type of coating that exists in the form of solid powder. It is produced by electrostatic spraying equipment, which charges the powder and adsorbs it onto the grounded surface of the workpiece. The powder is then heated and cured to form a uniform and firm coating film.

[0003] Electrostatic powder coatings have the following characteristics: (1) Environmental friendliness: They contain no solvents and emit no VOCs (volatile organic compounds) during application, meeting environmental protection requirements. (2) High utilization rate: Unattached powder can be recycled and reused, with a coating utilization rate of over 95%. (3) Excellent performance: The coating film has high hardness, wear resistance, strong corrosion resistance, and long-lasting and stable color. (4) Convenient application: A thick coating (50-100μm) can be achieved with a single spray, saving steps.

[0004] Electrostatic powder coatings are commonly used for surface coating of metal furniture, automotive parts, appliance housings, and building profiles (such as aluminum alloy doors and windows). With increasingly stringent environmental protection requirements and rising demands for product quality, electrostatic powder coatings, as a green, environmentally friendly, and high-performance coating product, have an even broader application prospect. However, existing electrostatic powder coatings suffer from insufficient hardness or adhesion, making the coating film easily scratched or prone to localized peeling and flaking. Therefore, there is an urgent need to develop a powder coating with high adhesion and high hardness suitable for electrophoretic substrates. Summary of the Invention

[0005] The purpose of this invention is to provide a powder coating with high adhesion and high hardness that is applicable to electrophoretic substrates.

[0006] The implementation process of this invention is as follows:

[0007] A powder coating with high adhesion and high hardness suitable for use on electrophoretic substrates, comprising the following components in parts by weight:

[0008] Epoxy resin, 55-65 parts by weight;

[0009] Hydroxyacrylate resin, 30-40 parts by weight;

[0010] Polyvinylidene fluoride, 5-10 parts by weight;

[0011] Isocyanurate, 5-6 parts by weight;

[0012] Polyamide, 5-6 parts by weight;

[0013] Bismuth oxide / porous hydroxyapatite / titanium dioxide composite, 20-30 parts by weight;

[0014] Mullite-doped zirconium oxide composite, 8-15 parts by weight;

[0015] Polyvinyl alcohol short fiber, 0.5 to 2 parts by weight.

[0016] Furthermore, the preparation method of the bismuth oxide / porous hydroxyapatite / titanium dioxide composite includes the following steps:

[0017] (S1) Tetrabutyl titanate and isopropanol are stirred and mixed to obtain solution A;

[0018] (S2) Isopropanol, water, glacial acetic acid, bismuth nitrate pentahydrate, polyvinylpyrrolidone and porous hydroxyapatite are stirred and mixed to obtain suspension B;

[0019] (S3) Under stirring conditions, suspension B is added dropwise to solution A and left to stand overnight to age, forming a homogeneous gel;

[0020] (S4) The gel was dispersed in water and subjected to a hydrothermal reaction. After the reaction was completed, the gel was washed and dried to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0021] Further, in step (S1), the mass-to-volume ratio of tetrabutyl titanate to isopropanol is 10 g: (4-6) ml, and the stirring time is 30-40 min; the mass-to-volume ratio of tetrabutyl titanate in step (S1) to isopropanol in step (S2) is 10 g: (4-6) ml; in step (S2), the volume ratio of isopropanol, water, and glacial acetic acid is (4-6): (2.5-3): (4-6); the mass ratio of tetrabutyl titanate to bismuth nitrate pentahydrate, polyvinylpyrrolidone, and porous hydroxyapatite is 10: (0.2-0.3): (0.4-0.6): (0.4-0.6).

[0022] Furthermore, in step (S4), the temperature of the hydrothermal reaction is 180–200°C, and the reaction time is 2–3 hours.

[0023] Furthermore, the preparation method of the mullite-doped zirconium oxide composite includes the following steps:

[0024] (L1) Zirconium oxychloride, mullite, carboxymethyl cellulose and water were added to the reactor and hydrothermal reaction was carried out. After the reaction was completed, the mixture was filtered and freeze-dried to obtain the zirconium oxide precursor.

[0025] (L2) The zirconia precursor was placed in a tube furnace and calcined and cooled to room temperature to obtain a mullite-doped zirconia composite.

[0026] Further, in step (L1), the mass ratio of zirconium oxychloride to mullite and carboxymethyl cellulose is 10:(1-2):(0.3-0.5); the mass-volume ratio of zirconium oxychloride to water is 10g:(80-90)ml; the hydrothermal reaction temperature is 200-205℃, and the time is 4-5 hours.

[0027] Furthermore, in step (L2), the calcination temperature is 900–950°C, the calcination time is 1.5–2 hours, and the cooling rate is 15°C / min.

[0028] Furthermore, the method for preparing the polyvinyl alcohol short fibers includes the following steps:

[0029] (X1) Polyvinyl alcohol is dissolved in water and stirred evenly to obtain a spinning solution; the spinning solution is electrospun at room temperature using an electrospinning device, and a uniform fiber membrane is obtained by drying using an aluminum foil roller as a collection device; then the fiber membrane is cross-linked in glutaraldehyde vapor to prepare a water-insoluble polyvinyl alcohol nanofiber membrane.

[0030] (X2) After adding water to the polyvinyl alcohol nanofiber membrane, it was crushed and homogenized to obtain a polyvinyl alcohol short fiber suspension. After centrifugation and drying, polyvinyl alcohol short fibers were obtained.

[0031] Further, in step (X1), the concentration of the spinning solution is 1-1.5 g / ml; the parameters of the electrospinning equipment are set as follows: spinning flow rate is 1.0 mL / h; spinning voltage is 16-18 kV; roller speed is 600 r / min; spinning distance is 11-12 cm from the needle to the roller; and deposition time is 11-12 minutes.

[0032] Furthermore, the powder coating also includes pigments, which are 2 to 4 parts by weight, and the pigments are selected from carbon black or iron oxide red.

[0033] The positive effects of this invention:

[0034] (1) The powder coating with high adhesion and high hardness on electrophoretic substrate described in this invention uses epoxy resin and hydroxyl acrylic resin as resin materials, and adds polyvinylidene fluoride to improve the adhesion of the powder coating.

[0035] (2) The powder coating with high adhesion and high hardness on electrophoretic substrate described in this invention contains a novel bismuth oxide / porous hydroxyapatite / titanium dioxide composite to increase the adhesion of the powder coating, absorb ultraviolet light, and increase the weather resistance of the electrostatic powder coating.

[0036] (3) The powder coating with high adhesion and high hardness on electrophoretic substrate described in this invention contains a novel mullite-doped zirconium oxide composite to improve the corrosion resistance, wear resistance, hardness and high temperature resistance of the electrostatic powder coating.

[0037] (4) The powder coating with high adhesion and high hardness on electrophoretic substrate described in this invention has added polyvinyl alcohol short fibers to improve the adhesion, corrosion resistance and impact resistance of the electrostatic powder coating.

[0038] (5) The powder coating with high adhesion and high hardness applicable to electrophoretic substrates described in this invention has high adhesion, high hardness, corrosion resistance and weather resistance. Detailed Implementation

[0039] The present invention will be further described below with reference to the embodiments.

[0040] In a first aspect, the present invention provides a powder coating with high adhesion and high hardness applicable to electrophoretic substrates, comprising the following components in parts by weight:

[0041] Epoxy resin, 55-65 parts by weight;

[0042] Hydroxyacrylate resin, 30-40 parts by weight;

[0043] Polyvinylidene fluoride, 5-10 parts by weight;

[0044] Isocyanurate, 5-6 parts by weight;

[0045] Polyamide, 5-6 parts by weight;

[0046] Bismuth oxide / porous hydroxyapatite / titanium dioxide composite, 20-30 parts by weight;

[0047] Mullite-doped zirconium oxide composite, 8-15 parts by weight;

[0048] Polyvinyl alcohol short fiber, 0.5 to 2 parts by weight;

[0049] Pigment, 2 to 4 parts by weight.

[0050] Pigments are added as needed.

[0051] The preparation method of the bismuth oxide / porous hydroxyapatite / titanium dioxide composite includes the following steps:

[0052] (S1) Mix 10g tetrabutyl titanate and 4-6ml isopropanol for 30-40 minutes to obtain solution A;

[0053] (S2) Mix 4-6 ml isopropanol, 2.5-3 ml water, 4-6 ml glacial acetic acid, 0.2-0.3 g bismuth nitrate pentahydrate, 0.4-0.6 g polyvinylpyrrolidone and 0.4-0.6 g porous hydroxyapatite to obtain suspension B;

[0054] (S3) Under stirring conditions, suspension B is added dropwise to solution A and left to stand overnight to age, forming a homogeneous gel;

[0055] (S4) The gel was dispersed in water and subjected to a hydrothermal reaction at 180-200℃ for 2-3 hours. After the reaction was completed, the gel was washed and dried to obtain the bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0056] The preparation method of the mullite-doped zirconium oxide composite includes the following steps:

[0057] (L1) Add 10g zirconium oxychloride, 1-2g mullite, 0.3-0.5g carboxymethyl cellulose and 80-90ml water to the reactor, and carry out hydrothermal reaction at 200-205℃ for 4-5 hours. After the reaction is completed, filter and freeze dry to obtain zirconium oxide precursor.

[0058] (L2) The zirconia precursor was placed in a tube furnace and calcined at 900-950°C for 1.5-2 hours. The temperature was then lowered (at a rate of 15°C / min) to room temperature to obtain a mullite-doped zirconia composite.

[0059] The method for preparing the polyvinyl alcohol short fibers includes the following steps:

[0060] (X1) Polyvinyl alcohol is dissolved in water and stirred evenly to obtain a spinning solution with a concentration of 1-1.5 g / ml; the spinning solution is electrospun at room temperature using an electrospinning device, with an aluminum foil roller as the collection device, and dried to obtain a uniform fiber membrane; then the fiber membrane is placed in glutaraldehyde vapor with a mass concentration of 20%-25% for crosslinking for 22-24 h to prepare a water-insoluble polyvinyl alcohol nanofiber membrane; the parameters of the electrospinning device are set as follows: spinning flow rate of 1.0 mL / h; spinning voltage of 16-18 kV; roller speed of 600 r / min; spinning distance of 11-12 cm between the needle tip and the roller; and deposition time of 11-12 minutes.

[0061] (X2) After adding water, the polyvinyl alcohol nanofiber membrane is broken down and homogenized to obtain a suspension of polyvinyl alcohol short fibers. After centrifugation and drying, polyvinyl alcohol short fibers are obtained. This invention does not limit the amount of water added during the homogenization process, as long as homogenization can be achieved.

[0062] The pigment is selected from any one of titanium dioxide, carbon black, iron oxide red, fluorescent pigments, or pearlescent pigments.

[0063] Secondly, the present invention provides a method for preparing the above-mentioned powder coating, specifically comprising mixing 55-65 parts by weight of epoxy resin, 30-40 parts by weight of hydroxyl acrylic resin, 5-10 parts by weight of polyvinylidene fluoride, 5-6 parts by weight of isocyanurate, 5-6 parts by weight of polyamide, 20-30 parts by weight of bismuth oxide / porous hydroxyapatite / titanium dioxide composite, 8-15 parts by weight of mullite-doped zirconium oxide composite, 0.5-2 parts by weight of polyvinyl alcohol short fiber, and 2-4 parts by weight of pigment, and then adding the mixture to a twin-screw extruder and extruding it at 95-110°C. After cooling, a coating block is obtained, and after pulverization, a powder coating with a particle size of 25-55 μm is obtained, which is suitable for use on electrophoretic substrates with high adhesion and high hardness.

[0064] Example 1

[0065] A powder coating with high adhesion and high hardness suitable for electrophoretic substrates is composed of the following components in parts by weight: 60 parts by weight of epoxy resin, 35 parts by weight of hydroxyl acrylic resin, 8 parts by weight of polyvinylidene fluoride, 5 parts by weight of isocyanurate, 5 parts by weight of polyamide, 25 parts by weight of bismuth oxide / porous hydroxyapatite / titanium dioxide composite, 10 parts by weight of mullite-doped zirconium oxide composite, and 1.5 parts by weight of polyvinyl alcohol short fibers.

[0066] The preparation method of the bismuth oxide / porous hydroxyapatite / titanium dioxide composite includes the following steps:

[0067] (S1) Mix 10g tetrabutyl titanate and 5ml isopropanol for 35min to obtain solution A;

[0068] (S2) Mix 5 ml isopropanol, 2.8 ml water, 5 ml glacial acetic acid, 0.25 g bismuth nitrate pentahydrate, 0.5 g polyvinylpyrrolidone and 0.5 g porous hydroxyapatite to obtain suspension B;

[0069] (S3) Under stirring conditions, suspension B is added dropwise to solution A and left to stand overnight to age, forming a homogeneous gel;

[0070] (S4) The gel was dispersed in water and subjected to a hydrothermal reaction at 190°C for 2.5 h. After the reaction was completed, the gel was washed and dried to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0071] The preparation method of the mullite-doped zirconium oxide composite includes the following steps:

[0072] (L1) Add 10g zirconium oxychloride, 1.5g mullite, 0.4g carboxymethyl cellulose and 85ml water to the reactor, and carry out hydrothermal reaction at 203℃ for 4.5 hours. After the reaction is completed, filter and freeze dry to obtain zirconium oxide precursor.

[0073] (L2) The zirconia precursor was placed in a tube furnace and calcined at 930°C for 1.7 hours. The temperature was then lowered (at a rate of 15°C / min) to room temperature to obtain a mullite-doped zirconia composite.

[0074] The method for preparing the polyvinyl alcohol short fibers includes the following steps:

[0075] (X1) Polyvinyl alcohol was dissolved in water and stirred evenly to obtain a spinning solution with a concentration of 1.3 g / ml. The spinning solution was electrospun at room temperature using an electrospinning device, with an aluminum foil roller as the collection device. After drying, a uniform fiber membrane was obtained. The fiber membrane was then placed in glutaraldehyde vapor with a mass concentration of 25% for crosslinking for 24 h to prepare a water-insoluble polyvinyl alcohol nanofiber membrane. The parameters of the electrospinning device were set as follows: spinning flow rate of 1.0 mL / h; spinning voltage of 17 kV; roller speed of 600 r / min; spinning distance of 11 cm between the needle tip and the roller; and deposition time of 12 minutes.

[0076] (X2) After adding water, the polyvinyl alcohol nanofiber membrane is broken down and homogenized to obtain a suspension of polyvinyl alcohol short fibers. After centrifugation and drying, polyvinyl alcohol short fibers are obtained. This invention does not limit the amount of water added during the homogenization process, as long as homogenization can be achieved.

[0077] The above-mentioned method for preparing a powder coating with high adhesion and high hardness suitable for electrophoretic substrates involves weighing the raw materials according to the formula in Example 1, mixing them, adding the mixture to a twin-screw extruder and extruding it at 100°C. After cooling, a coating block is obtained, which is then pulverized to obtain a powder coating with high adhesion and high hardness suitable for electrophoretic substrates with a particle size of 25-55 μm.

[0078] Example 2

[0079] A powder coating with high adhesion and high hardness suitable for electrophoretic substrates is composed of the following components in parts by weight: epoxy resin, 55 parts by weight; hydroxyl acrylic resin, 40 parts by weight; polyvinylidene fluoride, 10 parts by weight; isocyanurate, 5 parts by weight; polyamide, 6 parts by weight; bismuth oxide / porous hydroxyapatite / titanium dioxide composite, 30 parts by weight; mullite-doped zirconium oxide composite, 8 parts by weight; polyvinyl alcohol short fiber, 2 parts by weight; and carbon black, 4 parts by weight.

[0080] The preparation method of the bismuth oxide / porous hydroxyapatite / titanium dioxide composite includes the following steps:

[0081] (S1) Mix 10g tetrabutyl titanate and 6ml isopropanol for 40min to obtain solution A;

[0082] (S2) Mix 6 ml isopropanol, 3 ml water, 4 ml glacial acetic acid, 0.3 g bismuth nitrate pentahydrate, 0.4 g polyvinylpyrrolidone and 0.4 g porous hydroxyapatite to obtain suspension B;

[0083] (S3) Under stirring conditions, suspension B is added dropwise to solution A and left to stand overnight to age, forming a homogeneous gel;

[0084] (S4) The gel was dispersed in water and subjected to a hydrothermal reaction at 200°C for 2 hours. After the reaction was completed, the gel was washed and dried to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0085] The preparation method of the mullite-doped zirconium oxide composite includes the following steps:

[0086] (L1) Add 10g zirconium oxychloride, 1g mullite, 0.3g carboxymethyl cellulose and 80ml water to the reactor, and carry out hydrothermal reaction at 200℃ for 5 hours. After the reaction is completed, filter and freeze dry to obtain zirconium oxide precursor.

[0087] (L2) The zirconia precursor was placed in a tube furnace and calcined at 950°C for 1.5 hours, then cooled (at a rate of 15°C / min) to room temperature to obtain a mullite-doped zirconia composite.

[0088] The method for preparing the polyvinyl alcohol short fibers includes the following steps:

[0089] (X1) Polyvinyl alcohol was dissolved in water and stirred evenly to obtain a spinning solution with a concentration of 1 g / ml. The spinning solution was electrospun at room temperature using an electrospinning device, with an aluminum foil roller as the collection device. After drying, a uniform fiber membrane was obtained. The fiber membrane was then placed in glutaraldehyde vapor with a mass concentration of 25% for crosslinking for 22 h to prepare a water-insoluble polyvinyl alcohol nanofiber membrane. The parameters of the electrospinning device were set as follows: spinning flow rate of 1.0 mL / h; spinning voltage of 18 kV; roller speed of 600 r / min; spinning distance of 11 cm between the needle tip and the roller; and deposition time of 12 minutes.

[0090] (X2) After adding water, the polyvinyl alcohol nanofiber membrane is broken down and homogenized to obtain a suspension of polyvinyl alcohol short fibers. After centrifugation and drying, polyvinyl alcohol short fibers are obtained. This invention does not limit the amount of water added during the homogenization process, as long as homogenization can be achieved.

[0091] The above-mentioned method for preparing a powder coating with high adhesion and high hardness suitable for electrophoretic substrates involves weighing the raw materials according to the formula in Example 2, mixing them, adding the mixture to a twin-screw extruder and extruding it at 95°C. After cooling, a coating block is obtained, which is then pulverized to obtain a powder coating with high adhesion and high hardness suitable for electrophoretic substrates with a particle size of 25-55 μm.

[0092] Example 3

[0093] A powder coating with high adhesion and high hardness suitable for electrophoretic substrates is composed of the following components in parts by weight: epoxy resin, 65 parts by weight; hydroxyl acrylic resin, 30 parts by weight; polyvinylidene fluoride, 5 parts by weight; isocyanurate, 6 parts by weight; polyamide, 5 parts by weight; bismuth oxide / porous hydroxyapatite / titanium dioxide composite, 20 parts by weight; mullite-doped zirconium oxide composite, 15 parts by weight; polyvinyl alcohol short fibers, 0.5 parts by weight; iron oxide red, 2 parts by weight.

[0094] The preparation method of the bismuth oxide / porous hydroxyapatite / titanium dioxide composite includes the following steps:

[0095] (S1) Mix 10g tetrabutyl titanate and 4ml isopropanol for 30min to obtain solution A;

[0096] (S2) Mix 4 ml isopropanol, 2.5 ml water, 6 ml glacial acetic acid, 0.2 g bismuth nitrate pentahydrate, 0.6 g polyvinylpyrrolidone and 0.6 g porous hydroxyapatite to obtain suspension B;

[0097] (S3) Under stirring conditions, suspension B is added dropwise to solution A and left to stand overnight to age, forming a homogeneous gel;

[0098] (S4) The gel was dispersed in water and subjected to a hydrothermal reaction at 180°C for 3 hours. After the reaction was completed, the gel was washed and dried to obtain the bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0099] The preparation method of the mullite-doped zirconium oxide composite includes the following steps:

[0100] (L1) Add 10g zirconium oxychloride, 2g mullite, 0.5g carboxymethyl cellulose and 90ml water to the reactor, and carry out hydrothermal reaction at 205℃ for 4 hours. After the reaction is completed, filter and freeze dry to obtain zirconium oxide precursor.

[0101] (L2) The zirconia precursor was placed in a tube furnace and calcined at 900°C for 2 hours. The temperature was then lowered (at a rate of 15°C / min) to room temperature to obtain a mullite-doped zirconia composite.

[0102] The method for preparing the polyvinyl alcohol short fibers includes the following steps:

[0103] (X1) Polyvinyl alcohol was dissolved in water and stirred evenly to obtain a spinning solution with a concentration of 1.5 g / ml. The spinning solution was electrospun at room temperature using an electrospinning device, with an aluminum foil roller as the collection device. After drying, a uniform fiber membrane was obtained. The fiber membrane was then placed in glutaraldehyde vapor with a mass concentration of 20% for 24 h to prepare a water-insoluble polyvinyl alcohol nanofiber membrane. The parameters of the electrospinning device were set as follows: spinning flow rate of 1.0 mL / h; spinning voltage of 16 kV; roller speed of 600 r / min; spinning distance of 12 cm between the needle tip and the roller; and deposition time of 11 minutes.

[0104] (X2) After adding water, the polyvinyl alcohol nanofiber membrane is broken down and homogenized to obtain a suspension of polyvinyl alcohol short fibers. After centrifugation and drying, polyvinyl alcohol short fibers are obtained. This invention does not limit the amount of water added during the homogenization process, as long as homogenization can be achieved.

[0105] The above-mentioned method for preparing a powder coating with high adhesion and high hardness suitable for electrophoretic substrates involves weighing the raw materials according to the formula in Example 3, mixing them, adding the mixture to a twin-screw extruder and extruding it at 95°C. After cooling, a coating block is obtained, which is then pulverized to obtain a powder coating with a particle size of 25-55 μm suitable for electrophoretic substrates.

[0106] Example 4

[0107] A powder coating with high adhesion and high hardness suitable for electrophoretic substrates is composed of the following components in parts by weight: epoxy resin, 60 parts by weight; hydroxyl acrylic resin, 40 parts by weight; polyvinylidene fluoride, 5 parts by weight; isocyanurate, 5 parts by weight; polyamide, 6 parts by weight; bismuth oxide / porous hydroxyapatite / titanium dioxide composite, 25 parts by weight; mullite-doped zirconium oxide composite, 15 parts by weight; polyvinyl alcohol short fibers, 2 parts by weight; and iron oxide red, 3 parts by weight.

[0108] The preparation method of the bismuth oxide / porous hydroxyapatite / titanium dioxide composite includes the following steps:

[0109] (S1) Mix 10g tetrabutyl titanate and 6ml isopropanol for 40min to obtain solution A;

[0110] (S2) Mix 6 ml isopropanol, 3 ml water, 4 ml glacial acetic acid, 0.3 g bismuth nitrate pentahydrate, 0.5 g polyvinylpyrrolidone and 0.5 g porous hydroxyapatite to obtain suspension B;

[0111] (S3) Under stirring conditions, suspension B is added dropwise to solution A and left to stand overnight to age, forming a homogeneous gel;

[0112] (S4) The gel was dispersed in water and subjected to a hydrothermal reaction at 185°C for 2.5 h. After the reaction was completed, the gel was washed and dried to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0113] The preparation method of the mullite-doped zirconium oxide composite includes the following steps:

[0114] (L1) Add 10g zirconium oxychloride, 2g mullite, 0.3g carboxymethyl cellulose and 80ml water to the reactor, and carry out hydrothermal reaction at 200℃ for 4 hours. After the reaction is completed, filter and freeze dry to obtain zirconium oxide precursor.

[0115] (L2) The zirconia precursor was placed in a tube furnace and calcined at 900°C for 1.5 hours, then cooled (at a rate of 15°C / min) to room temperature to obtain a mullite-doped zirconia composite.

[0116] The method for preparing the polyvinyl alcohol short fibers includes the following steps:

[0117] (X1) Polyvinyl alcohol was dissolved in water and stirred evenly to obtain a spinning solution with a concentration of 1.2 g / ml. The spinning solution was electrospun at room temperature using an electrospinning device, with an aluminum foil roller as the collection device. After drying, a uniform fiber membrane was obtained. The fiber membrane was then placed in glutaraldehyde vapor with a mass concentration of 20% for crosslinking for 22 h to prepare a water-insoluble polyvinyl alcohol nanofiber membrane. The parameters of the electrospinning device were set as follows: spinning flow rate of 1.0 mL / h; spinning voltage of 16 kV; roller speed of 600 r / min; spinning distance of 12 cm between the needle tip and the roller; and deposition time of 11 minutes.

[0118] (X2) After adding water, the polyvinyl alcohol nanofiber membrane is broken down and homogenized to obtain a suspension of polyvinyl alcohol short fibers. After centrifugation and drying, polyvinyl alcohol short fibers are obtained. This invention does not limit the amount of water added during the homogenization process, as long as homogenization can be achieved.

[0119] The above-mentioned method for preparing a powder coating with high adhesion and high hardness suitable for electrophoretic substrates involves weighing the raw materials according to the formula in Example 4, mixing them, adding the mixture to a twin-screw extruder and extruding it at 100°C. After cooling, a coating block is obtained, which is then pulverized to obtain a powder coating with a particle size of 25-55 μm suitable for electrophoretic substrates.

[0120] Example 5

[0121] A powder coating with high adhesion and high hardness suitable for electrophoretic substrates is composed of the following components in parts by weight: epoxy resin, 65 parts by weight; hydroxyl acrylic resin, 30 parts by weight; polyvinylidene fluoride, 10 parts by weight; isocyanurate, 6 parts by weight; polyamide, 6 parts by weight; bismuth oxide / porous hydroxyapatite / titanium dioxide composite, 20 parts by weight; mullite-doped zirconium oxide composite, 15 parts by weight; polyvinyl alcohol short fiber, 1.5 parts by weight; and carbon black, 4 parts by weight.

[0122] The preparation method of the bismuth oxide / porous hydroxyapatite / titanium dioxide composite includes the following steps:

[0123] (S1) Mix 10g tetrabutyl titanate and 4ml isopropanol for 40min to obtain solution A;

[0124] (S2) Mix 6 ml isopropanol, 3 ml water, 6 ml glacial acetic acid, 0.3 g bismuth nitrate pentahydrate, 0.6 g polyvinylpyrrolidone and 0.4 g porous hydroxyapatite to obtain suspension B;

[0125] (S3) Under stirring conditions, suspension B is added dropwise to solution A and left to stand overnight to age, forming a homogeneous gel;

[0126] (S4) The gel was dispersed in water and subjected to a hydrothermal reaction at 200°C for 3 hours. After the reaction was completed, the gel was washed and dried to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0127] The preparation method of the mullite-doped zirconium oxide composite includes the following steps:

[0128] (L1) Add 10g zirconium oxychloride, 2g mullite, 0.5g carboxymethyl cellulose and 90ml water to the reactor, and carry out hydrothermal reaction at 205℃ for 4 hours. After the reaction is completed, filter and freeze dry to obtain zirconium oxide precursor.

[0129] (L2) The zirconia precursor was placed in a tube furnace and calcined at 900°C for 1.5 hours, then cooled (at a rate of 15°C / min) to room temperature to obtain a mullite-doped zirconia composite.

[0130] The method for preparing the polyvinyl alcohol short fibers includes the following steps:

[0131] (X1) Polyvinyl alcohol was dissolved in water and stirred evenly to obtain a spinning solution with a concentration of 1-1.5 g / ml; the spinning solution was electrospun at room temperature using an electrospinning device, with an aluminum foil roller as the collection device, and dried to obtain a uniform fiber membrane; then the fiber membrane was placed in glutaraldehyde vapor with a mass concentration of 20% for crosslinking for 24 h to prepare a water-insoluble polyvinyl alcohol nanofiber membrane; the parameters of the electrospinning device were set as follows: spinning flow rate of 1.0 mL / h; spinning voltage of 16 kV; roller speed of 600 r / min; spinning distance of 12 cm between the needle tip and the roller; and deposition time of 12 minutes.

[0132] (X2) After adding water, the polyvinyl alcohol nanofiber membrane is broken down and homogenized to obtain a suspension of polyvinyl alcohol short fibers. After centrifugation and drying, polyvinyl alcohol short fibers are obtained. This invention does not limit the amount of water added during the homogenization process, as long as homogenization can be achieved.

[0133] The above-mentioned method for preparing a powder coating with high adhesion and high hardness suitable for electrophoretic substrates involves weighing the raw materials according to the formula in Example 5, mixing them, adding the mixture to a twin-screw extruder and extruding it at 110°C. After cooling, a coating block is obtained, which is then pulverized to obtain a powder coating with high adhesion and high hardness suitable for electrophoretic substrates with a particle size of 25-55 μm.

[0134] Comparative Example 1

[0135] The composition is the same as that of the powder coating described in Example 1, except that 8 parts by weight of polyvinylidene fluoride are not added.

[0136] Comparative Example 2

[0137] The composition is the same as that of the powder coating described in Example 1, except that 25 parts by weight of the bismuth oxide / porous hydroxyapatite / titanium dioxide composite are not added.

[0138] Comparative Example 3

[0139] The composition is the same as that of the powder coating described in Example 1, except that 10 parts by weight of the mullite-doped zirconium oxide composite are not added.

[0140] Comparative Example 4

[0141] The composition is the same as that of the powder coating described in Example 1, except that 1.5 parts by weight of polyvinyl alcohol short fibers are not added.

[0142] Performance testing:

[0143] Examples 1 and Comparative Examples 1-4 were sprayed onto wall ventilation products using existing technology to obtain the sprayed products.

[0144] (I) 100-Character Test

[0145] According to ASTM D3359, "Coating Adhesion Test (Tape Method)", the judgment criterion is that the adhesion of the coating on the product surface reaches 4B or above.

[0146] Test procedure: (1) Draw ten lines on the surface of the product; (2) Apply 3M 898 tape to the test position; (3) After 90±30 seconds, pull the unbonded end to the back at a 180° angle; (4) Observe whether there is any peeling or detachment on the product surface.

[0147] The experimental results are shown in Table 1. As can be seen from the table, the adhesion of the coatings in Comparative Examples 1, 2 and 4 decreased significantly without the addition of polyvinylidene fluoride, bismuth oxide / porous hydroxyapatite / titanium dioxide composite or polyvinyl alcohol short fibers.

[0148] Table 1. Results of the 100-grid test

[0149]

[0150] (II) Pencil Hardness Test

[0151] According to ASTM D 3363, "Standard Test Method for Determining the Hardness of a Coating with a Pencil Hardness of 1H". Judgment criteria: No hard scratches on the product surface coating at pencil hardness 1H, and no chisel marks at pencil hardness 2H.

[0152] Pencil hardness range: 6B-5B-4B-3B-2B-B-HB-FH-2H-3H-4H-5H-6H.

[0153] Test procedure: (1) Grind the Zhonghua brand pencil lead to a 90° angle with 400# coarse sandpaper and press the film at a 45° angle; (2) Observe whether there are any changes on the surface of the product.

[0154] The experimental results are shown in Table 2. As can be seen from the table, the hardness of the coating in Comparative Example 3, which did not contain the mullite-doped zirconium oxide composite, decreased significantly.

[0155] Table 2. Results of the pencil hardness test.

[0156]

[0157] (III) NSS 5% Salt Spray Test

[0158] Test standard: ASTM B117. Equipment used: CZ-140AW. Judgment criterion: Product surface corrosion reaches level nine or above.

[0159] The test parameters are shown in Table 3:

[0160] Table 3 shows the test parameters.

[0161]

[0162]

[0163] The experimental results are shown in Table 4. As can be seen from the table, the corrosion resistance of the coatings in Comparative Examples 3 and 4 also decreased significantly when no mullite-doped zirconium oxide composite or polyvinyl alcohol short fiber was added.

[0164] Table 4. Results of NSS 5% Salt Spray Test

[0165]

[0166]

[0167] (iv) Temperature and humidity test

[0168] Test standards: in accordance with ASTM D2247 "Standard Test Method for Water Resistance of Coatings" and ASTM D3359 "Standard Test Method for Adhesion Measurement Using Tape" Method B.

[0169] Judgment criteria: The product surface coating shows no obvious changes and can pass the adhesion test to achieve 4B or above.

[0170] Equipment used: High and low temperature alternating damp heat test chamber / C4-600E.

[0171] Test procedure: (1) Place the product in a high and low temperature heat exchange chamber: maintain the temperature at 38±2℃ and the humidity at 95% for 96 hours; (2) Take it out and rinse it with clean water, and observe whether there are any changes at room temperature; (3) Use method B to perform an adhesion test, draw ten lines on the surface of the product, apply 3M 898 tape to the test position, and pull the unbonded end at a 180° angle to the back after 90±30 seconds; (4) Observe whether there is any peeling or detachment on the surface of the product.

[0172] The experimental results are shown in Table 5. As can be seen from the table, the weather resistance of the coatings in Comparative Examples 2 and 3 decreased significantly without the addition of bismuth oxide / porous hydroxyapatite / titanium dioxide composite or mullite-doped zirconium oxide composite.

[0173] Table 5. Results of Temperature and Humidity Tests

[0174]

[0175]

[0176] (V) High and low temperature aging test

[0177] Test standard: GB / T4893.7 ASTM D3359 Standard Test Method for Determining Adhesion Using Adhesive Tape, Method B.

[0178] Judgment criteria: The product surface is free from damage and visible changes, and can pass the adhesion test to achieve 4B or above.

[0179] Equipment and Model Used: High and Low Temperature Alternating Damp Heat Test Chamber / C4-180PRO

[0180] Test process: (1) Place the product at two extreme temperatures of -18℃ and 49℃ for 12 hours each as one cycle, and test for a total of 24 hours for one cycle, and observe the changes; (2) Use method B to perform the adhesion test, draw ten lines on the surface of the product, apply 3M 898 tape to the test position, and pull the unbonded end at a 180° angle to the back after 90±30 seconds; (3) Observe whether there is peeling or detachment on the surface of the product.

[0181] The experimental results are shown in Table 6. It can be seen from the table that the high and low temperature aging resistance of the coatings in Comparative Examples 3 and 4 decreased significantly without the addition of mullite-doped zirconium oxide composite or polyvinyl alcohol short fibers.

[0182]

[0183]

[0184] Table 6 Results of High and Low Temperature Aging Test

[0185] (vi) LAB value test

[0186] Test standards: Based on ASTM D2244, "Test method for calculating color difference by means of instrumental determination of color coordinates"; based on CIE Lab SCI 10° / D65 standard.

[0187] Judgment criteria: The judgment must be satisfied together with L: 92.65, a: -0.84, b: 1.92, △E≤1.

[0188] Equipment and model used: Spectrophotometer (model: CM-700D).

[0189] Test process: (1) Zero point and whiteboard calibration of the instrument; (2) Sample preparation; (3) Measurement of the sample; (4) Record test data.

[0190] The experimental results are shown in Table 7. As can be seen from the table, the LAB values ​​of Example 1 and Comparative Examples 1-4 all meet the requirements.

[0191] Table 7. Results of LAB value test.

[0192]

[0193]

[0194] (vii) Gloss test

[0195] Test standard: Based on ASTM D523, "Specular gloss test method". Judgment standard: The gloss level must meet 30°±5°.

[0196] Equipment used: Gloss meter.

[0197] Test process: (1) The instrument is zero-point calibrated; (2) The sample is placed on the test platform and the incident angle is 60°; (3) The test data is recorded.

[0198] The experimental results are shown in Table 8. As can be seen from the table, the gloss of Example 1 and Comparative Examples 1-4 all meet the requirements.

[0199] Table 8. Results of Glossiness Test

[0200]

[0201]

[0202] Other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and this application is not limited to the precise structures described above, and various modifications and changes can be made without departing from its scope.

Claims

1. A powder coating with high adhesion and high hardness suitable for use on electrophoretic substrates, characterized in that, Composed of the following components in parts by weight composition: Epoxy resin, 55-65 parts by weight; Hydroxy acrylic resin, 30-40 parts by weight; Polyvinylidene fluoride, 5-10 parts by weight; Isocyanurate, 5-6 parts by weight; Polyamide, 5-6 parts by weight; Bismuth oxide / porous hydroxyapatite / titanium dioxide composite, 20-30 parts by weight; Mullite-doped zirconium oxide composite, 8-15 parts by weight; Polyvinyl alcohol short fiber, 0.5~2 parts by weight; The preparation method of the bismuth oxide / porous hydroxyapatite / titanium dioxide composite includes the following steps: (S1) Tetrabutyl titanate and isopropanol are stirred and mixed to obtain solution A; (S2) Isopropanol, water, glacial acetic acid, bismuth nitrate pentahydrate, polyvinylpyrrolidone and porous hydroxyapatite are stirred and mixed to obtain suspension B; (S3) Under stirring conditions, suspension B is added dropwise to solution A and left to stand overnight to age, forming a homogeneous gel; (S4) The gel was dispersed in water and subjected to a hydrothermal reaction. After the reaction was completed, the gel was washed and dried to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

2. The powder coating with high adhesion and high hardness applicable to electrophoretic substrates according to claim 1, characterized in that: In step (S1), the mass-to-volume ratio of tetrabutyl titanate to isopropanol is 10 g: (4~6) mL, and the stirring time is 30~40 min; the mass-to-volume ratio of tetrabutyl titanate in step (S1) to isopropanol in step (S2) is 10 g: (4~6) mL; in step (S2), the volume ratio of isopropanol, water, and glacial acetic acid is (4~6): (2.5~3): (4~6); the mass ratio of tetrabutyl titanate to bismuth nitrate pentahydrate, polyvinylpyrrolidone, and porous hydroxyapatite is 10: (0.2~0.3): (0.4~0.6): (0.4~0.6).

3. The powder coating with high adhesion and high hardness applicable to electrophoretic substrates according to claim 1, characterized in that: In step (S4), the hydrothermal reaction temperature is 180~200℃ and the reaction time is 2~3h.

4. The powder coating with high adhesion and high hardness applicable to electrophoretic substrates according to claim 1, characterized in that, The preparation method of the mullite-doped zirconium oxide composite includes the following steps: (L1) Zirconium oxychloride, mullite, carboxymethyl cellulose and water were added to the reactor and hydrothermal reaction was carried out. After the reaction was completed, the mixture was filtered and freeze-dried to obtain the zirconium oxide precursor. (L2) The zirconia precursor was placed in a tube furnace and calcined and cooled to room temperature to obtain a mullite-doped zirconia composite.

5. The powder coating with high adhesion and high hardness applicable to electrophoretic substrates according to claim 4, characterized in that: In step (L1), the mass ratio of zirconium oxychloride to mullite and carboxymethyl cellulose is 10:(1~2):(0.3~0.5); the mass-volume ratio of zirconium oxychloride to water is 10 g:(80~90) mL; the hydrothermal reaction temperature is 200~205℃ and the time is 4~5 hours.

6. The powder coating with high adhesion and high hardness applicable to electrophoretic substrates according to claim 4, characterized in that: In step (L2), the calcination temperature is 900~950℃, the calcination time is 1.5~2 hours, and the cooling rate is 15℃ / min.

7. The powder coating with high adhesion and high hardness applicable to electrophoretic substrates according to claim 1, characterized in that, The method for preparing the polyvinyl alcohol short fibers includes the following steps: (X1) Polyvinyl alcohol is dissolved in water and stirred evenly to obtain a spinning solution; the spinning solution is electrospun at room temperature using an electrospinning device, and an aluminum foil roller is used as a collection device. After drying, a uniform fiber membrane is obtained; then the fiber membrane is placed in glutaraldehyde vapor for crosslinking to prepare a water-insoluble polyvinyl alcohol nanofiber membrane. (X2) After adding water to the polyvinyl alcohol nanofiber membrane, it was crushed and homogenized to obtain a polyvinyl alcohol short fiber suspension. After centrifugation and drying, polyvinyl alcohol short fibers were obtained.

8. The powder coating with high adhesion and high hardness applicable to electrophoretic substrates according to claim 7, characterized in that: In step (X1), the concentration of the spinning solution is 1~1.5 g / mL; the parameters of the electrospinning equipment are set as follows: spinning flow rate is 1.0 mL / h; spinning voltage is 16~18 kV; roller speed is 600 r / min; spinning distance is 11~12 cm from the needle to the roller; and deposition time is 11~12 minutes.

9. The powder coating with high adhesion and high hardness applicable to electrophoretic substrates according to claim 1, characterized in that: The powder coating also includes pigments, which are 2 to 4 parts by weight and are selected from carbon black or iron oxide red.

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