High-adhesion and high-hardness powder coating applied to electrophoretic substrate

Abstract

The invention belongs to the technical field of electrostatic powder coatings, and particularly relates to a high-adhesion and high-hardness powder coating applied to an electrophoretic substrate. The powder coating is composed of the following components in parts by weight: 55-65 parts of epoxy resin; 30-40 parts by weight of hydroxy acrylic resin; 5 to 10 parts by weight of polyvinylidene fluoride; 5 to 6 parts by weight of isocyanurate; 5-6 parts by weight of polyamide; 20 to 30 parts by weight of a bismuth oxide / porous hydroxyapatite / titanium dioxide compound; 8 to 15 parts by weight of a mullite doped zirconium oxide compound; 0.5-2 parts by weight of polyvinyl alcohol short fiber; and 2-4 parts by weight of a pigment. The high-adhesive-force and high-hardness powder coating applied to the electrophoresis base material has high adhesive force, high hardness, corrosion resistance and weather resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrostatic powder coatings, and in particular relates to a powder coating with high adhesion and high hardness which is applicable to electrophoretic substrates. Background Art

[0002] Electrostatic powder coating is a type of coating in the form of solid powder. The powder is charged by electrostatic spraying equipment, adsorbed on the grounded workpiece surface, and then heated and cured to form a uniform and firm coating film.

[0003] Electrostatic powder coatings have the following characteristics: (1) Environmentally friendly: They do not contain solvents and do not emit 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, strong wear and corrosion resistance, and long-lasting and stable color. (4) Convenient application: A thicker coating (50-100μm) can be achieved in one spray application, saving steps.

[0004] Electrostatic powder coatings are commonly used for surface coatings on metal furniture, automotive parts, electrical appliance housings, and architectural profiles (such as aluminum alloy doors and windows). With increasingly stringent environmental protection requirements and increasing demands for product quality, electrostatic powder coatings, as a green, environmentally friendly, and high-performance coating product, are poised for even greater application. However, existing electrostatic powder coatings suffer from insufficient hardness and adhesion, making the coating susceptible to scratches, localized peeling, and shedding. Therefore, there is an urgent need to develop a powder coating with high adhesion and hardness for electrophoretic substrates. Summary of the Invention

[0005] The object of the present invention is to provide a powder coating with high adhesion and high hardness which is practical for electrophoresis substrates.

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

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

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

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

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

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

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

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

[0014] Mullite-doped zirconia composite, 8 to 15 parts by weight;

[0015] Polyvinyl alcohol staple fibers, 0.5 to 2 parts by weight.

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

[0017] (S1) stirring and mixing tetrabutyl titanate and isopropyl alcohol to obtain solution A;

[0018] (S2) mixing isopropyl alcohol, water, glacial acetic acid, bismuth nitrate pentahydrate, polyvinyl pyrrolidone, and porous hydroxyapatite to obtain a suspension B;

[0019] (S3) adding suspension B dropwise to solution A under stirring, and allowing to stand overnight to form a uniform gel;

[0020] (S4) dispersing the gel in water and performing a hydrothermal reaction. After the reaction is completed, washing and drying are performed to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0021] Furthermore, in step (S1), the mass volume ratio of tetrabutyl titanate and isopropyl alcohol is 10 g:(4-6) ml, and the stirring mixing time is 30-40 min; the mass volume ratio of tetrabutyl titanate in step (S1) and isopropyl alcohol in step (S2) is 10 g:(4-6) ml; in step (S2), the volume ratio of isopropyl alcohol, water, and glacial acetic acid is (4-6):(2.5-3):(4-6); the mass ratio of tetrabutyl titanate to bismuth nitrate pentahydrate, polyvinyl pyrrolidone, 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 h.

[0023] Furthermore, the preparation method of the mullite-doped zirconia composite comprises the following steps:

[0024] (L1) adding zirconium oxychloride, mullite, carboxymethyl cellulose, and water to a reactor to carry out a hydrothermal reaction, filtering after the reaction, and freeze-drying to obtain a zirconium oxide precursor;

[0025] (L2) placing the zirconium oxide precursor in a tube furnace, calcining it, and cooling it to room temperature to obtain a mullite-doped zirconium oxide composite.

[0026] Furthermore, in step (L1), the mass ratio of the zirconium oxychloride to mullite and carboxymethyl cellulose is 10:(1-2):(0.3-0.5); the mass volume ratio of the zirconium oxychloride to water is 10 g:(80-90) ml; the hydrothermal reaction temperature is 200-205° C., 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 preparation method of the polyvinyl alcohol staple fiber comprises the following steps:

[0029] (X1) dissolving polyvinyl alcohol in water and stirring uniformly to obtain a spinning solution; electrospinning the spinning solution using an electrospinning apparatus at room temperature, collecting the solution using an aluminum foil drum, and drying the resulting film to obtain a uniform fiber membrane; and then crosslinking the fiber membrane in glutaraldehyde vapor to obtain a water-insoluble polyvinyl alcohol nanofiber membrane;

[0030] (X2) The polyvinyl alcohol nanofiber membrane is added to water and then crushed and homogenized to obtain a polyvinyl alcohol short fiber suspension, which is then centrifuged and dried to obtain polyvinyl alcohol short fibers.

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

[0032] Furthermore, the powder coating further comprises a pigment, the pigment is 2 to 4 parts by weight, and the pigment is selected from carbon black or red iron oxide.

[0033] Positive effects of the present invention:

[0034] (1) The powder coating with high adhesion and high hardness applied to the electrophoretic substrate of the present invention uses epoxy resin and hydroxy 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 for electrophoretic substrates of the present invention is added with 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 for electrophoretic substrates of the present invention is added with 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 present invention adds polyvinyl alcohol short fibers to the powder coating with high adhesion and high hardness applied to the electrophoretic substrate 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 applied to the electrophoretic substrate of the present invention has high adhesion, high hardness, corrosion resistance and weather resistance. DETAILED DESCRIPTION

[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 having high adhesion and high hardness, which is suitable for use on an electrophoretic substrate and is composed of the following components in parts by weight:

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

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

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

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

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

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

[0047] Mullite-doped zirconia composite, 8 to 15 parts by weight;

[0048] Polyvinyl alcohol staple fibers, 0.5 to 2 parts by weight;

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

[0050] The pigment is added as needed.

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

[0052] (S1) 10 g of tetrabutyl titanate and 4-6 ml of isopropyl alcohol were stirred and mixed for 30-40 minutes to obtain solution A;

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

[0054] (S3) adding suspension B dropwise to solution A under stirring, and allowing to stand overnight to form a uniform gel;

[0055] (S4) dispersing the gel in water, performing a hydrothermal reaction at 180-200° C. for 2-3 hours, and washing and drying after the reaction to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0056] The preparation method of the mullite-doped zirconia composite comprises the following steps:

[0057] (L1) adding 10 g of zirconium oxychloride, 1-2 g of mullite, 0.3-0.5 g of carboxymethyl cellulose, and 80-90 ml of water to a reaction kettle, carrying out a hydrothermal reaction at 200-205° C. for 4-5 hours, filtering after the reaction, and freeze-drying to obtain a zirconium oxide precursor;

[0058] (L2) placing the zirconium oxide precursor in a tube furnace, calcining it at 900-950° C. for 1.5-2 hours, and cooling it to room temperature (at a cooling rate of 15° C. / min) to obtain a mullite-doped zirconium oxide composite.

[0059] The method for preparing the polyvinyl alcohol staple fibers comprises the following steps:

[0060] (X1) Dissolve polyvinyl alcohol in water and stir evenly to obtain a spinning solution with a concentration of 1 to 1.5 g / ml; electrospin the spinning solution at room temperature using an electrospinning device, use an aluminum foil roller as a collecting device, and obtain a uniform fiber membrane after drying; then place the fiber membrane in glutaraldehyde vapor with a mass concentration of 20% to 25% for cross-linking for 22 to 24 hours to prepare a water-insoluble polyvinyl alcohol nanofiber membrane; the parameter settings of the electrospinning device are a spinning flow rate of 1.0 mL / h; a spinning voltage of 16 to 18 kV; a roller speed of 600 r / min, a spinning distance of 11 to 12 cm from the needle to the roller, and a deposition time of 11 to 12 minutes.

[0061] (X2) Adding water to the polyvinyl alcohol nanofiber membrane, crushing it, and homogenizing it to obtain a polyvinyl alcohol staple fiber suspension, which is then centrifuged and dried to obtain polyvinyl alcohol staple fibers. The present invention does not limit the amount of water added during the homogenization process, as long as homogenization can be achieved.

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

[0063] In a second aspect, the present invention provides a method for preparing the above-mentioned powder coating, specifically, 55-65 parts by weight of epoxy resin, 30-40 parts by weight of hydroxy 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 zirconia composite, 0.5-2 parts by weight of polyvinyl alcohol short fibers and 2-4 parts by weight of pigment are mixed and added to a twin-screw extruder and extruded at 95-110°C. After cooling, a coating block is obtained, and after crushing, a powder coating with a particle size of 25-55 μm and high adhesion and hardness suitable for electrophoretic substrates is obtained.

[0064] Example 1

[0065] A powder coating with high adhesion and high hardness, which is suitable for use on electrophoretic substrates, is composed of the following components in parts by weight: 60 parts by weight of epoxy resin, 35 parts by weight of hydroxy 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 zirconia 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 comprises the following steps:

[0067] (S1) 10 g of tetrabutyl titanate and 5 ml of isopropyl alcohol were stirred and mixed for 35 min to obtain solution A;

[0068] (S2) 5 ml of isopropyl alcohol, 2.8 ml of water, 5 ml of glacial acetic acid, 0.25 g of bismuth nitrate pentahydrate, 0.5 g of polyvinylpyrrolidone, and 0.5 g of porous hydroxyapatite were stirred to obtain a suspension B;

[0069] (S3) adding suspension B dropwise to solution A under stirring, and allowing to stand overnight to form a uniform gel;

[0070] (S4) dispersing the gel in water and performing a hydrothermal reaction at 190° C. for 2.5 hours. After the reaction is completed, washing and drying are performed to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0071] The preparation method of the mullite-doped zirconia composite comprises the following steps:

[0072] (L1) adding 10 g of zirconium oxychloride, 1.5 g of mullite, 0.4 g of carboxymethyl cellulose, and 85 ml of water to a reactor, and conducting a hydrothermal reaction at 203° C. for 4.5 hours. After the reaction, filtering and freeze-drying were performed to obtain a zirconium oxide precursor;

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

[0074] The method for preparing the polyvinyl alcohol staple fiber comprises the following steps:

[0075] (X1) Polyvinyl alcohol is dissolved in water and stirred evenly to obtain a spinning solution with a concentration of 1.3 g / ml; the spinning solution is electrospun at room temperature using an electrospinning device, and an aluminum foil roller is used as a collecting device, and a uniform fiber membrane is obtained after drying; the fiber membrane is then placed in glutaraldehyde vapor with a mass concentration of 25% for cross-linking for 24 hours to prepare a water-insoluble polyvinyl alcohol nanofiber membrane; the parameter settings of the electrospinning device are a spinning flow rate of 1.0 mL / h; a spinning voltage of 17 kV; a roller speed of 600 r / min, a spinning distance of 11 cm from the needle to the roller, and a deposition time of 12 minutes.

[0076] (X2) Adding water to the polyvinyl alcohol nanofiber membrane, crushing it, and homogenizing it to obtain a polyvinyl alcohol staple fiber suspension, which is then centrifuged and dried to obtain polyvinyl alcohol staple fibers. The present 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 is specifically to weigh the raw materials according to the formula of Example 1, then mix them, add the mixed raw materials into a twin-screw extruder and extrude them at 100°C, cool them to obtain coating blocks, and then crush them to obtain a powder coating with high adhesion and high hardness suitable for electrophoretic substrates with a particle size of 25 to 55 μm.

[0078] Example 2

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

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

[0081] (S1) 10 g of tetrabutyl titanate and 6 ml of isopropyl alcohol were stirred and mixed for 40 min to obtain solution A;

[0082] (S2) 6 ml of isopropyl alcohol, 3 ml of water, 4 ml of glacial acetic acid, 0.3 g of bismuth nitrate pentahydrate, 0.4 g of polyvinylpyrrolidone, and 0.4 g of porous hydroxyapatite were stirred to obtain a suspension B;

[0083] (S3) adding suspension B dropwise to solution A under stirring, and allowing to stand overnight to form a uniform gel;

[0084] (S4) dispersing the gel in water and performing a hydrothermal reaction at 200° C. for 2 h. After the reaction is completed, washing and drying are performed to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0085] The preparation method of the mullite-doped zirconia composite comprises the following steps:

[0086] (L1) adding 10 g of zirconium oxychloride, 1 g of mullite, 0.3 g of carboxymethyl cellulose, and 80 ml of water to a reaction kettle, and conducting a hydrothermal reaction at 200° C. for 5 hours. After the reaction is completed, filtering and freeze-drying are performed to obtain a zirconium oxide precursor;

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

[0088] The method for preparing the polyvinyl alcohol staple fibers comprises the following steps:

[0089] (X1) Dissolve polyvinyl alcohol in water and stir evenly to obtain a spinning solution with a concentration of 1g / ml; electrospin the spinning solution at room temperature using an electrospinning device, use an aluminum foil roller as a collecting device, and dry to obtain a uniform fiber membrane; then place the fiber membrane in glutaraldehyde vapor with a mass concentration of 25% for cross-linking for 22 hours to prepare a water-insoluble polyvinyl alcohol nanofiber membrane; the parameter settings of the electrospinning device are a spinning flow rate of 1.0mL / h; a spinning voltage of 18kV; a roller speed of 600r / min, a spinning distance of 11cm between the needle and the roller, and a deposition time of 12 minutes.

[0090] (X2) Adding water to the polyvinyl alcohol nanofiber membrane, crushing it, and homogenizing it to obtain a polyvinyl alcohol staple fiber suspension, which is then centrifuged and dried to obtain polyvinyl alcohol staple fibers. The present 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 is specifically to weigh the raw materials according to the formula of Example 2, then mix them, add the mixed raw materials to a twin-screw extruder and extrude them at 95°C, cool them to obtain coating blocks, and then crush them to obtain a powder coating with high adhesion and high hardness suitable for electrophoretic substrates with a particle size of 25 to 55 μm.

[0092] Example 3

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

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

[0095] (S1) 10 g of tetrabutyl titanate and 4 ml of isopropyl alcohol were stirred and mixed for 30 min to obtain solution A;

[0096] (S2) 4 ml of isopropyl alcohol, 2.5 ml of water, 6 ml of glacial acetic acid, 0.2 g of bismuth nitrate pentahydrate, 0.6 g of polyvinylpyrrolidone, and 0.6 g of porous hydroxyapatite were stirred to obtain a suspension B;

[0097] (S3) adding suspension B dropwise to solution A under stirring, and allowing to stand overnight to form a uniform gel;

[0098] (S4) dispersing the gel in water and performing a hydrothermal reaction at 180° C. for 3 h. After the reaction is completed, washing and drying are performed to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0099] The preparation method of the mullite-doped zirconia composite comprises the following steps:

[0100] (L1) adding 10 g of zirconium oxychloride, 2 g of mullite, 0.5 g of carboxymethyl cellulose, and 90 ml of water to a reactor, and conducting a hydrothermal reaction at 205° C. for 4 hours. After the reaction, filtering and freeze-drying were performed to obtain a zirconium oxide precursor;

[0101] (L2) placing the zirconium oxide precursor in a tube furnace, calcining it at 900° C. for 2 hours, and cooling it (at a cooling rate of 15° C. / min) to room temperature to obtain a mullite-doped zirconium oxide composite.

[0102] The method for preparing the polyvinyl alcohol staple fiber comprises the following steps:

[0103] (X1) Dissolve polyvinyl alcohol in water and stir evenly to obtain a spinning solution with a concentration of 1.5g / ml; electrospin the spinning solution at room temperature using an electrospinning device, use an aluminum foil roller as a collecting device, and obtain a uniform fiber membrane after drying; then place the fiber membrane in glutaraldehyde vapor with a mass concentration of 20% for 24 hours to prepare a water-insoluble polyvinyl alcohol nanofiber membrane; the parameter settings of the electrospinning device are a spinning flow rate of 1.0mL / h; a spinning voltage of 16kV; a roller speed of 600r / min, a spinning distance of 12cm between the needle and the roller, and a deposition time of 11 minutes.

[0104] (X2) Adding water to the polyvinyl alcohol nanofiber membrane, crushing it, and homogenizing it to obtain a polyvinyl alcohol staple fiber suspension, which is then centrifuged and dried to obtain polyvinyl alcohol staple fibers. The present 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 is specifically to weigh the raw materials according to the formula of Example 3, then mix them, add the mixed raw materials to a twin-screw extruder and extrude them at 95°C, cool them to obtain coating blocks, and then crush them to obtain a powder coating with high adhesion and high hardness suitable for electrophoretic substrates with a particle size of 25 to 55 μm.

[0106] Example 4

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

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

[0109] (S1) 10 g of tetrabutyl titanate and 6 ml of isopropyl alcohol were stirred and mixed for 40 min to obtain solution A;

[0110] (S2) 6 ml of isopropyl alcohol, 3 ml of water, 4 ml of glacial acetic acid, 0.3 g of bismuth nitrate pentahydrate, 0.5 g of polyvinylpyrrolidone, and 0.5 g of porous hydroxyapatite were stirred to obtain a suspension B;

[0111] (S3) adding suspension B dropwise to solution A under stirring, and allowing to stand overnight to form a uniform gel;

[0112] (S4) dispersing the gel in water and performing a hydrothermal reaction at 185° C. for 2.5 h. After the reaction is completed, washing and drying are performed to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0113] The preparation method of the mullite-doped zirconia composite comprises the following steps:

[0114] (L1) adding 10 g of zirconium oxychloride, 2 g of mullite, 0.3 g of carboxymethyl cellulose, and 80 ml of water to a reaction kettle, and conducting a hydrothermal reaction at 200° C. for 4 hours. After the reaction is completed, filtering and freeze-drying are performed to obtain a zirconium oxide precursor;

[0115] (L2) placing the zirconium oxide precursor in a tube furnace, calcining it at 900° C. for 1.5 hours, and cooling it to room temperature (at a cooling rate of 15° C. / min) to obtain a mullite-doped zirconium oxide composite.

[0116] The method for preparing the polyvinyl alcohol staple fibers comprises the following steps:

[0117] (X1) Polyvinyl alcohol is dissolved in water and stirred evenly to obtain a spinning solution with a concentration of 1.2 g / ml; the spinning solution is electrospun at room temperature using an electrospinning device, and an aluminum foil roller is used as a collecting device, and a uniform fiber membrane is obtained after drying; the fiber membrane is then placed in glutaraldehyde vapor with a mass concentration of 20% for cross-linking for 22 hours to prepare a water-insoluble polyvinyl alcohol nanofiber membrane; the parameter settings of the electrospinning device are a spinning flow rate of 1.0 mL / h; a spinning voltage of 16 kV; a roller speed of 600 r / min, a spinning distance of 12 cm from the needle to the roller, and a deposition time of 11 minutes.

[0118] (X2) Adding water to the polyvinyl alcohol nanofiber membrane, crushing it, and homogenizing it to obtain a polyvinyl alcohol staple fiber suspension, which is then centrifuged and dried to obtain polyvinyl alcohol staple fibers. The present 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 is specifically to weigh the raw materials according to the formula of Example 4, then mix them, add the mixed raw materials into a twin-screw extruder and extrude them at 100°C, cool them to obtain coating blocks, and then crush them to obtain a powder coating with high adhesion and high hardness suitable for electrophoretic substrates with a particle size of 25 to 55 μm.

[0120] Example 5

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

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

[0123] (S1) 10 g of tetrabutyl titanate and 4 ml of isopropyl alcohol were stirred and mixed for 40 min to obtain solution A;

[0124] (S2) 6 ml of isopropyl alcohol, 3 ml of water, 6 ml of glacial acetic acid, 0.3 g of bismuth nitrate pentahydrate, 0.6 g of polyvinylpyrrolidone, and 0.4 g of porous hydroxyapatite were stirred to obtain a suspension B;

[0125] (S3) adding suspension B dropwise to solution A under stirring, and allowing to stand overnight to form a uniform gel;

[0126] (S4) dispersing the gel in water and performing a hydrothermal reaction at 200° C. for 3 h. After the reaction is completed, washing and drying are performed to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

[0127] The preparation method of the mullite-doped zirconia composite comprises the following steps:

[0128] (L1) adding 10 g of zirconium oxychloride, 2 g of mullite, 0.5 g of carboxymethyl cellulose, and 90 ml of water to a reactor, and conducting a hydrothermal reaction at 205° C. for 4 hours. After the reaction, filtering and freeze-drying were performed to obtain a zirconium oxide precursor;

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

[0130] The method for preparing the polyvinyl alcohol staple fiber comprises the following steps:

[0131] (X1) Dissolve polyvinyl alcohol in water and stir evenly to obtain a spinning solution with a concentration of 1 to 1.5 g / ml; electrospin the spinning solution at room temperature using an electrospinning device, use an aluminum foil roller as a collecting device, and obtain a uniform fiber membrane after drying; then place the fiber membrane in glutaraldehyde vapor with a mass concentration of 20% for cross-linking for 24 hours to prepare a water-insoluble polyvinyl alcohol nanofiber membrane; the parameter settings of the electrospinning device are a spinning flow rate of 1.0 mL / h; a spinning voltage of 16 kV; a roller speed of 600 r / min, a spinning distance of 12 cm from the needle to the roller, and a deposition time of 12 minutes.

[0132] (X2) Adding water to the polyvinyl alcohol nanofiber membrane, crushing it, and homogenizing it to obtain a polyvinyl alcohol staple fiber suspension, which is then centrifuged and dried to obtain polyvinyl alcohol staple fibers. The present 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 is specifically to weigh the raw materials according to the formula of Example 5, then mix them, add the mixed raw materials to a twin-screw extruder and extrude them at 110°C, cool them to obtain coating blocks, and then crush them to obtain a powder coating with high adhesion and high hardness suitable for electrophoretic substrates with a particle size of 25 to 55 μm.

[0134] Comparative Example 1

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

[0136] Comparative Example 2

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

[0138] Comparative Example 3

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

[0140] Comparative Example 4

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

[0142] Performance testing:

[0143] Example 1 and Comparative Examples 1 to 4 were sprayed on a wall vent product using existing technology to obtain a sprayed product.

[0144] (1) Hundred-grid test

[0145] According to ASTM D3359 "Coating Adhesion Test (Tape Method)". Judgment standard: The product surface coating adhesion reaches 4B or above.

[0146] Test process: (1) Draw ten lines on the surface of the product; (2) Apply 3M898 tape to the test location; (3) Pull the unbonded end at an angle of 180° to the back for 90±30 seconds; (4) Observe the surface of the product for peeling or shedding.

[0147] The experimental results are shown in Table 1. It can be seen from the table that when no polyvinylidene fluoride or bismuth oxide / porous hydroxyapatite / titanium dioxide composite or polyvinyl alcohol short fibers are added to Comparative Examples 1, 2 and 4, the adhesion of the coating is significantly reduced.

[0148] Table 1 Hundred-grid test results

[0149]

[0150] (2) Pencil hardness test

[0151] According to ASTM D 3363 "Standard Test Method for Determination of Film Hardness by Pencil Test". Judgment standard: The surface coating of the product has a pencil hardness of 1H with no hard scratches and 2H with no gouges.

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

[0153] Testing process: (1) Use 400# coarse sandpaper to grind the lead of a Zhonghua brand pencil into a 90° angle, and push the film at a 45° angle; (2) Observe whether there is any change on the surface of the product.

[0154] The experimental results are shown in Table 2. It can be seen from the table that in Comparative Example 3, no mullite-doped zirconia composite was added, and the hardness of the coating decreased significantly.

[0155] Table 2 Pencil hardness test results

[0156]

[0157] (3) NSS 5% salt spray test

[0158] Test standard: ASTM B117. Equipment used: CZ-140AW. Judgment standard: Product surface corrosion reaches level 9 or above.

[0159] 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. It can be seen from the table that in Comparative Examples 3 and 4, when no mullite-doped zirconia composite or polyvinyl alcohol short fibers are added, the corrosion resistance of the coatings is also significantly reduced.

[0164] Table 4 NSS 5% salt spray test results

[0165]

[0166]

[0167] (4) Temperature and humidity test

[0168] Test standards: Based on ASTM D2247 "Standard Test Method for Water Resistance of Coatings" and ASTM D3359 "Standard Test Method for Adhesion Using Tape" Method B.

[0169] Judgment criteria: There is no obvious change in the surface coating of the product, and it can pass the adhesion test of 4B or above.

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

[0171] Test process: (1) Place the product in a high and low temperature exchange humidity test 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 is any change at room temperature; (3) Use method B to perform adhesion test, draw ten lines on the surface of the product, apply 3M898 tape on the test position, and pull the unbonded end to the back at an angle of 180° for 90±30 seconds; (4) Observe whether there is any peeling or shedding on the surface of the product.

[0172] The experimental results are shown in Table 5. It can be seen from the table that when no bismuth oxide / porous hydroxyapatite / titanium dioxide composite or mullite-doped zirconia composite is added to Comparative Examples 2 and 3, the weather resistance of the coating is significantly reduced.

[0173] Table 5 Temperature and humidity test results

[0174]

[0175]

[0176] (5) High and low temperature aging test

[0177] Test standard: GB / T4893.7 ASTM D3359 "Standard test method for adhesion using tape" method B.

[0178] Judgment criteria: The product surface has no damage or visible changes, and can pass the adhesion test to 4B or above.

[0179] Equipment and model used: High and low temperature alternating humidity test chamber / C4-180PRO

[0180] Test process: (1) Place the product under two extreme temperatures of -18°C and 49°C for 12 hours each as one cycle, test one cycle for a total of 24 hours, and observe the changes; (2) Use method B to perform adhesion test, draw ten lines on the surface of the product, apply 3M898 tape on the test position, and pull the unbonded end to the back at an angle of 180° for 90±30 seconds; (3) Observe whether there is peeling or shedding on the surface of the product.

[0181] The experimental results are shown in Table 6. It can be seen from the table that when no mullite-doped zirconia composite or polyvinyl alcohol short fibers are added to Comparative Examples 3 and 4, the high and low temperature aging resistance of the coatings is significantly reduced.

[0182]

[0183]

[0184] Table 6 High and low temperature aging test results

[0185] (6) LAB value test

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

[0187] Judgment criteria: The judgment must meet the following conditions: L:92.65, a:-0.84, b:1.92, △E≤1.

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

[0189] Test process: (1) Calibrate the instrument to zero point and white plate; (2) Prepare the sample; (3) Measure the sample; (4) Record the test data.

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

[0191] Table 7 LAB value test results

[0192]

[0193]

[0194] (7) Gloss test

[0195] Test standard: Based on ASTM D523 "Specular Gloss Test Method". Judgment standard: The gloss must meet 30°±5°.

[0196] Equipment used: gloss meter.

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

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

[0199] Table 8 Glossiness test results

[0200]

[0201]

[0202] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the contents disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of this application and include common knowledge or customary techniques in the art that are not disclosed herein. The description and examples are to be considered merely as exemplary, and this application is not limited to the precise structures described above, and various modifications and variations may be made without departing from the scope thereof.

Claims

1. A powder coating with high adhesion and high hardness suitable for electrophoresis substrates, characterized in that: The following components are composed of parts by weight composition: Epoxy resin, 55-65 parts by weight; Hydroxylated 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 to 15 parts by weight; Polyvinyl alcohol staple fibers, 0.5 to 2 parts by weight.

2. The powder coating with high adhesion and high hardness for electrophoresis substrate according to claim 1, characterized in that: The preparation method of the bismuth oxide / porous hydroxyapatite / titanium dioxide composite comprises the following steps: (S1) stirring and mixing tetrabutyl titanate and isopropyl alcohol to obtain solution A; (S2) mixing isopropyl alcohol, water, glacial acetic acid, bismuth nitrate pentahydrate, polyvinyl pyrrolidone, and porous hydroxyapatite to obtain a suspension B; (S3) adding suspension B dropwise to solution A under stirring, and allowing to stand overnight to form a uniform gel; (S4) dispersing the gel in water and performing a hydrothermal reaction. After the reaction is completed, washing and drying are performed to obtain a bismuth oxide / porous hydroxyapatite / titanium dioxide composite.

3. The powder coating with high adhesion and high hardness for electrophoresis substrate according to claim 2, characterized in that: In step (S1), the mass volume ratio of tetrabutyl titanate and isopropyl alcohol is 10 g: (4-6) ml, and the stirring mixing time is 30-40 min; the mass volume ratio of tetrabutyl titanate in step (S1) and isopropyl alcohol in step (S2) is 10 g: (4-6) ml; in step (S2), the volume ratio of isopropyl alcohol, water, and glacial acetic acid is (4-6): (2.5-3): (4-6); the mass ratio of tetrabutyl titanate to bismuth nitrate pentahydrate, polyvinyl pyrrolidone, and porous hydroxyapatite is 10: (0.2-0.3): (0.4-0.6): (0.4-0.6).

4. The powder coating with high adhesion and high hardness for electrophoresis substrate according to claim 2, characterized in that: In step (S4), the temperature of the hydrothermal reaction is 180-200° C., and the reaction time is 2-3 hours.

5. The powder coating with high adhesion and high hardness for electrophoresis substrate according to claim 1, characterized in that: The preparation method of the mullite-doped zirconia composite comprises the following steps: (L1) adding zirconium oxychloride, mullite, carboxymethyl cellulose and water into a reactor to carry out a hydrothermal reaction, filtering after the reaction is completed, and freeze-drying to obtain a zirconium oxide precursor; (L2) The zirconia precursor is placed in a tube furnace, calcined, and cooled to room temperature to obtain a mullite-doped zirconia composite.

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

7. The powder coating with high adhesion and high hardness for electrophoresis substrate according to claim 5, characterized in that: 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.

8. The powder coating with high adhesion and high hardness for electrophoresis substrate according to claim 1, characterized in that: The preparation method of the polyvinyl alcohol staple fiber comprises the following steps: (X1) dissolving polyvinyl alcohol in water and stirring uniformly to obtain a spinning solution; electrospinning the spinning solution at room temperature using an electrospinning device, collecting it on an aluminum foil drum, and drying it to obtain a uniform fiber membrane; and then placing the fiber membrane in glutaraldehyde vapor for cross-linking to prepare a water-insoluble polyvinyl alcohol nanofiber membrane; (X2) The polyvinyl alcohol nanofiber membrane is added to water, crushed and homogenized to obtain a polyvinyl alcohol short fiber suspension, which is then centrifuged and dried to obtain polyvinyl alcohol short fibers.

9. The powder coating with high adhesion and high hardness for electrophoresis substrate according to claim 8, characterized in that: In step (X1), the concentration of the spinning solution is 1-1.5 g / ml; the parameter settings of the electrospinning equipment are: a spinning flow rate of 1.0 mL / h; a spinning voltage of 16-18 kV; a roller speed of 600 r / min, a spinning distance of 11-12 cm between the needle and the roller, and a deposition time of 11-12 minutes.

10. The powder coating with high adhesion and high hardness for electrophoresis substrate according to claim 1, characterized in that: The powder coating further comprises a pigment, the pigment is 2 to 4 parts by weight, and the pigment is selected from carbon black or red iron oxide.

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