PU coating-based electronic product housing and preparation method thereof

Abstract

The invention relates to the technical field of electronic products. The invention provides an electronic product shell based on a PU coating and a preparation method thereof. The invention comprises the following steps: using a glass fiber board or a PC board as a substrate, spraying an organosilicon coating and a PU coating in sequence on the surface of the substrate by a spraying method, so as to construct an electronic product shell with an aging-resistant, corrosion-resistant, wear-resistant and super-hydrophobic surface; introducing modified zirconium phosphate into the organosilicon coating and the PU coating as a filler; synthesizing a prepolymer of organosilicon-modified waterborne polyurethane using polytetrahydrofuran, hydroxyl-terminated polydimethylsiloxane and isophorone diisocyanate as raw materials under the catalysis of dibutyltin dilaurate, using 2,2-bis(hydroxymethyl)propionic acid as a hydrophilic chain extender, using pentaerythritol triacrylate as a photocuring active component, using a benzophenone quaternary ammonium salt compound as a capping agent, using triethanolamine as a neutralizing agent, adding deionized water for emulsification to prepare the organosilicon-modified waterborne polyurethane.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic products, and in particular to a PU-coated electronic product housing and a preparation method thereof. Background Art

[0002] With the development of society, various electronic products have gradually become necessities in people's lives, and consumers have higher standards for the functions and appearance of various electronic products.

[0003] Most existing electronic products use metal or plastic as their shell materials. For example, in the preparation of plastic shells, the traditional method is to first form the PU leather and then stick it to the fiberglass board or PC board. This has the problem of relatively complicated process. While spraying PU coating directly on the fiberglass board / PC board can simplify the process, the prepared shell also has limited protective properties such as wear resistance, aging resistance, and water resistance, and cannot provide long-term protection for electronic products. Summary of the Invention

[0004] The object of the present invention is to provide an electronic product housing based on PU coating and a preparation method thereof, so as to solve the problems in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for preparing an electronic product housing based on a PU coating comprises the following steps:

[0007] S1: Preparation of silicone coating using epoxy resin, epoxy-terminated silicone and modified zirconium phosphate;

[0008] S2: Immersing the substrate in an ethanol solution of Michaelis' acid for acidification treatment, then spraying an organic silicon coating on the surface of the substrate and drying it to obtain a pretreated substrate;

[0009] S3: Preparation of PU coating using modified zirconium phosphate, silicone-modified waterborne polyurethane, and photoinitiator;

[0010] S4: Spraying the PU coating on the surface of the pretreated substrate and performing light curing to obtain an electronic product housing based on the PU coating.

[0011] Furthermore, the substrate is one of a glass fiber board and a PC board.

[0012] Furthermore, the working conditions of the acidification treatment are: temperature of 28-38°C and time of 2-3h.

[0013] Furthermore, the modified zirconium phosphate, epoxy resin, and epoxy-terminated silicone are compounded in a mass ratio of 2:25:15.

[0014] Furthermore, the preparation of the organosilicon coating comprises the following steps:

[0015] (1) Mix hydroxy silicone oil and 3-(2,3)-glycidoxypropylmethyldimethoxysilane, heat to 88-92°C and keep warm for 5-6 hours, and distill under reduced pressure to obtain epoxy-terminated silicone;

[0016] (2) Mix the modified zirconium phosphate, epoxy resin and epoxy-terminated silicone, heat to 138-142°C and keep warm for 3-4 hours, then add deionized water and acetic acid, continue to keep warm for 3-4 hours, add dibutyltin dilaurate, keep warm for 4-5 hours, add curing agent, cool and discharge to obtain silicone coating.

[0017] Furthermore, the composition of the PU coating is, by weight, 1-5 parts of modified zirconium phosphate, 18-33 parts of silicone-modified waterborne polyurethane, and 0.1-0.2 parts of photoinitiator.

[0018] Furthermore, the preparation of the modified zirconium phosphate comprises the following steps:

[0019] 1) Mix deionized water and phosphoric acid, add zirconium oxychloride octahydrate, transfer to a hydrothermal kettle, heat to 190-200°C and keep warm for 4-5 hours, wash, centrifuge, and dry to obtain α-zirconium phosphate nanosheets;

[0020] 2) Mix 3-(2,3)-glycidoxypropylmethyldimethoxysilane, ethanol, and deionized water, adjust the pH of the solution to 3.9-4.1, stir for 1-2 hours, add α-zirconium phosphate nanosheets, stir for 22-24 hours, centrifuge, wash, and dry to obtain epoxidized zirconium phosphate;

[0021] 3) Mix the benzophenone quaternary ammonium salt compound, epoxidized zirconium phosphate, and chloroform, add Amberlyst-15 ion exchange resin, transfer to an ultrasonic water bath, heat to 58-62°C and maintain for 2-3 hours, filter, and rotary evaporate to obtain modified zirconium phosphate.

[0022] Furthermore, the preparation of the organosilicon-modified waterborne polyurethane comprises the following steps:

[0023] Mix polytetrahydrofuran, hydroxyl-terminated polydimethylsiloxane and acetone, add isophorone diisocyanate, 2,2-bis(hydroxymethyl)propionic acid and dibutyltin dilaurate, heat to 68-72°C and keep warm for 3-4 hours, add pentaerythritol triacrylate and acetone, heat to 78-82°C and keep warm for 3-4 hours, add benzophenone quaternary ammonium salt compound and acetone, heat to 88-92°C and keep warm for 3-4 hours, cool to 30-35°C, add triethanolamine, keep warm for 20-30 minutes, add deionized water, emulsify for 1 hour, and rotary evaporate to obtain a silicone-modified waterborne polyurethane with a solid content of 27-32%.

[0024] Further, the preparation of the benzophenone quaternary ammonium salt compound comprises the following steps:

[0025] A. Mix 2,4-dihydroxybenzophenone, potassium carbonate, and acetone, add dimethylaminoethyl chloride hydrochloride, raise the temperature to 52-56°C and maintain for 11-12 hours, add dilute hydrochloric acid and NaOH solution in sequence, extract with ether, separate the liquids, and add anhydrous sodium sulfate to dry to obtain an intermediate preparation;

[0026] B. Mix the intermediate preparation and bromooctane, raise the temperature to 118-122°C and keep it for 3-4 hours, cool it, recrystallize it in ethyl acetate 3-5 times, and filter it to obtain a benzophenone quaternary ammonium salt compound.

[0027] Furthermore, the working conditions of the light curing treatment are: a 1kW high-pressure mercury lamp, a distance of 25cm, and a time of 20s.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention provides an electronic product housing based on PU coating and a preparation method thereof. Through component and process optimization, a glass fiber board or a PC board is used as a substrate, and an organic silicon coating and a PU coating are sprayed sequentially on the surface of the substrate by spraying, thereby constructing an electronic product housing with an aging-resistant, corrosion-resistant, wear-resistant and super-hydrophobic surface.

[0030] In order to improve the corrosion resistance of the shell and prevent the prepared coating from having problems such as cracks and gaps, the present invention introduces layered α-zirconium phosphate with high mechanical strength, good acid and alkali resistance, and high thermal stability into the silicone coating and the PU coating as a filler. In order to improve the uniformity of the dispersion of the α-zirconium phosphate in the coating, the α-zirconium phosphate is modified with 3-(2,3)-glycidoxypropylmethyldimethoxysilane to prepare epoxidized zirconium phosphate. Then, the epoxy-hydroxy ring is opened and grafted with a benzophenone quaternary ammonium salt compound. The benzophenone quaternary ammonium salt compound is prepared by a two-step process using 2,4-dihydroxy-benzophenone, dimethylaminochloroethane hydrochloride, and alkyl bromide as raw materials. While improving the hydrophobicity of the shell, it also imparts excellent UV resistance to the shell, thereby improving the aging resistance of the shell.

[0031] In order to improve the adhesion between the PU coating and the substrate, the substrate is first acidified, and then a room temperature curable silicone coating is coated on the surface of the substrate. Epoxy-terminated silicone is prepared using hydroxy silicone oil and 3-(2,3)-glycidoxypropylmethyldimethoxysilane. Then, the epoxy group is subjected to ring-opening polymerization and blended with modified zirconium phosphate and epoxy resin. Polyamide is used as a curing agent to prepare a silicone coating with good flexibility, high toughness and strong adhesion, thereby greatly improving the weather resistance of the casing.

[0032] In the present invention, a PU coating is prepared using modified zirconium phosphate, silicone-modified waterborne polyurethane, and a photoinitiator. The PU coating is sprayed on the surface of a pretreated substrate and subjected to light curing treatment to obtain a super-hydrophobic surface with good aging resistance, strong corrosion resistance, and excellent wear resistance, thereby improving the protection of electronic products.

[0033] Among them, the silicone-modified water-based polyurethane is prepared by using polytetrahydrofuran, hydroxyl-terminated polydimethylsiloxane, and isophorone diisocyanate as raw materials, synthesizing a prepolymer under the catalysis of dibutyltin dilaurate, using 2,2-bis(hydroxymethyl)propionic acid as a hydrophilic chain extender, pentaerythritol triacrylate as a photocuring active ingredient, benzophenone quaternary ammonium salt compound as a capping agent, and triethanolamine as a neutralizing agent, and adding deionized water for emulsification to prepare the silicone-modified water-based polyurethane; at the same time, the introduction of benzophenone quaternary ammonium salt compound improves its photocuring rate and effect, thereby improving the antibacterial, wear resistance and corrosion resistance of the shell surface, greatly extending the service life of the shell. DETAILED DESCRIPTION

[0034] The following will provide a clear and complete description of the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] It should be noted that if the embodiments of the present invention involve directional indications such as up, down, left, right, front, and back, such directional indications are only used to explain a specific posture, such as the relative position relationship between components, the movement status, etc. If the specific posture changes, the directional indication will also change accordingly. In addition, the technical solutions between the various embodiments may be combined with each other, but they must be based on the premise that they can be implemented by ordinary technicians in this field. If the combination of technical solutions is mutually inconsistent or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0036] The technical solutions of the present invention are further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely used to explain the present invention and are not intended to limit the present invention.

[0037] Example 1: A method for preparing an electronic product housing based on a PU coating, comprising the following steps:

[0038] S1: preparing a silicone coating using epoxy resin, epoxy-terminated silicone, modified zirconium phosphate, and a curing agent;

[0039] The modified zirconium phosphate, epoxy resin, epoxy-terminated silicone and curing agent are compounded in a mass ratio of 2:25:15:5;

[0040] The preparation of silicone coatings includes the following steps:

[0041] (1) Mix 7 g of hydroxy silicone oil and 1.1 g of 3-(2,3)-glycidoxypropylmethyldimethoxysilane, heat to 88 °C and keep warm for 6 h, and then distill under reduced pressure to obtain epoxy-terminated silicone;

[0042] (2) 2 g of modified zirconium phosphate, 25 g of epoxy resin E-51, and 15 g of epoxy-terminated silicone were mixed, heated to 138 ° C and kept warm for 4 h, 20 mL of deionized water and 0.14 g of acetic acid were added, and the mixture was kept warm for 3 h. 2 drops of dibutyltin dilaurate were added and the mixture was kept warm for 4 h. 5 g of curing agent was added and the mixture was cooled and discharged to obtain a silicone coating;

[0043] The preparation of the modified zirconium phosphate comprises the following steps:

[0044] 1) Mix 21.6 mL of deionized water and 18.4 mL of phosphoric acid, add 4 g of zirconium oxychloride octahydrate, transfer to a hydrothermal autoclave, heat to 190°C and hold for 5 h, wash, centrifuge, and dry to obtain α-zirconium phosphate nanosheets;

[0045] 2) Mix 5 mL of 3-(2,3)-glycidoxypropylmethyldimethoxysilane, 80 mL of ethanol, and 20 mL of deionized water, adjust the pH of the solution to 3.9, stir for 1 hour, add 1 g of α-zirconium phosphate nanosheets, stir for 22 hours, centrifuge, wash, and dry to obtain epoxidized zirconium phosphate;

[0046] 3) Mix 1.2 g of benzophenone quaternary ammonium salt, 0.7 g of epoxidized zirconium phosphate, and 5 mL of chloroform, add 0.5 g of Amberlyst-15 ion exchange resin, transfer to an ultrasonic water bath, heat to 58°C and maintain for 3 h, filter, and rotary evaporate to obtain modified zirconium phosphate;

[0047] The preparation of the benzophenone quaternary ammonium salt compound comprises the following steps:

[0048] A. Mix 0.05 mol of 2,4-dihydroxybenzophenone, 0.07 mol of potassium carbonate, and 50 mL of acetone, add 0.1 mol of dimethylaminochloroethane hydrochloride, raise the temperature to 52°C, and maintain for 12 hours. Then, add dilute hydrochloric acid and NaOH solution in sequence. Extract with ether, separate the liquids, and dry over anhydrous sodium sulfate to obtain an intermediate preparation.

[0049] B. Mix 1 g of the intermediate preparation and 3 g of bromooctane, heat to 118°C and keep warm for 4 hours, cool, recrystallize three times from ethyl acetate, and filter to obtain a benzophenone quaternary ammonium salt compound;

[0050] S2: The substrate is immersed in a 3 wt % ethanol solution of Michaelis acid for acidification, and then an organic silicone coating is sprayed on the surface of the substrate and dried to obtain a pretreated substrate; the substrate is a glass fiber board;

[0051] The working conditions of acidification treatment were: temperature 28 °C, time 3 h;

[0052] S3: Preparation of PU coating using modified zirconium phosphate, silicone-modified waterborne polyurethane, and photoinitiator;

[0053] The composition of the PU coating is, in parts by mass: 1 part modified zirconium phosphate, 18 parts silicone-modified waterborne polyurethane, and 0.1 part photoinitiator;

[0054] The preparation of silicone-modified waterborne polyurethane includes the following steps:

[0055] 12 g of polytetrahydrofuran, 5 g of hydroxyl-terminated polydimethylsiloxane, and 15 mL of acetone were mixed, 14 g of isophorone diisocyanate, 2 g of 2,2-bis(hydroxymethyl)propionic acid, and 0.2 g of dibutyltin dilaurate were added, the temperature was raised to 68°C and kept warm for 4 h, 4 g of pentaerythritol triacrylate and 10 mL of acetone were added, the temperature was raised to 78°C and kept warm for 3 h, 3.2 g of benzophenone quaternary ammonium salt compound and 10 mL of acetone were added, the temperature was raised to 88°C and kept warm for 4 h, the mixture was cooled to 30°C, 3.1 g of triethanolamine was added, the mixture was kept warm for 20 min, deionized water was added, the mixture was emulsified for 1 h, and the mixture was rotary evaporated to obtain a silicone-modified waterborne polyurethane with a solid content of 29%;

[0056] S4: Spraying the PU coating onto the surface of the pretreated substrate and performing photocuring to obtain an electronic product housing based on the PU coating; the working conditions of the photocuring treatment are: selecting a 1kW high-pressure mercury lamp, a distance of 25cm, and a time of 20s; the photoinitiator is 2,4,6-trimethylbenzoyl-xylylphosphine oxide.

[0057] Example 2: A method for preparing an electronic product housing based on a PU coating, comprising the following steps:

[0058] S1: preparing a silicone coating using epoxy resin, epoxy-terminated silicone, modified zirconium phosphate, and a curing agent;

[0059] The modified zirconium phosphate, epoxy resin, epoxy-terminated silicone and curing agent are compounded in a mass ratio of 2:25:15:5;

[0060] The preparation of silicone coatings includes the following steps:

[0061] (1) Mix 7 g of hydroxy silicone oil and 1.1 g of 3-(2,3)-glycidoxypropylmethyldimethoxysilane, heat to 90 °C and keep warm for 5.5 h, and distill under reduced pressure to obtain epoxy-terminated silicone;

[0062] (2) 2 g of modified zirconium phosphate, 25 g of epoxy resin E-51, and 15 g of epoxy-terminated silicone were mixed, heated to 140 ° C and kept warm for 3.5 h, 20 mL of deionized water and 0.14 g of acetic acid were added, and the mixture was kept warm for another 3.5 h. 2 drops of dibutyltin dilaurate were added, and the mixture was kept warm for 4.5 h. 5 g of curing agent was added, and the mixture was cooled and discharged to obtain a silicone coating;

[0063] The preparation of the modified zirconium phosphate comprises the following steps:

[0064] 1) Mix 21.6 mL of deionized water and 18.4 mL of phosphoric acid, add 4 g of zirconium oxychloride octahydrate, transfer to a hydrothermal autoclave, heat to 195°C and hold for 4.5 h, wash, centrifuge, and dry to obtain α-zirconium phosphate nanosheets;

[0065] 2) Mix 5 mL of 3-(2,3)-glycidoxypropylmethyldimethoxysilane, 80 mL of ethanol, and 20 mL of deionized water, adjust the solution pH to 4, stir for 1.5 h, add 1 g of α-zirconium phosphate nanosheets, stir for 23 h, centrifuge, wash, and dry to obtain epoxidized zirconium phosphate;

[0066] 3) Weigh 1.2 g of benzophenone quaternary ammonium salt compound, 0.7 g of epoxidized zirconium phosphate, and 5 mL of chloroform, mix, add 0.5 g of Amberlyst-15 ion exchange resin, transfer to an ultrasonic water bath, heat to 60°C and hold for 2.5 h, filter, and rotary evaporate to obtain modified zirconium phosphate;

[0067] The preparation of the benzophenone quaternary ammonium salt compound comprises the following steps:

[0068] A. Mix 0.05 mol of 2,4-dihydroxybenzophenone, 0.07 mol of potassium carbonate, and 50 mL of acetone, add 0.1 mol of dimethylaminochloroethane hydrochloride, raise the temperature to 53°C, and maintain for 11.5 hours. Then, add dilute hydrochloric acid and NaOH solution in sequence. Extract with ether, separate the layers, and dry over anhydrous sodium sulfate to obtain an intermediate preparation.

[0069] B. Mix 1 g of the intermediate preparation and 3 g of bromooctane, heat to 120°C and keep warm for 3.5 hours, cool, recrystallize four times in ethyl acetate, and filter to obtain a benzophenone quaternary ammonium salt compound;

[0070] S2: The substrate is immersed in a 3 wt % ethanol solution of Michaelis acid for acidification, and then an organic silicone coating is sprayed on the surface of the substrate and dried to obtain a pretreated substrate; the substrate is a glass fiber board;

[0071] The working conditions of acidification treatment are: temperature 35 °C, time 2.5 h;

[0072] S3: Preparation of PU coating using modified zirconium phosphate, silicone-modified waterborne polyurethane, and photoinitiator;

[0073] The composition of the PU coating is, in parts by mass: 3 parts of modified zirconium phosphate, 26 parts of silicone-modified waterborne polyurethane, and 0.15 parts of photoinitiator;

[0074] The preparation of silicone-modified waterborne polyurethane includes the following steps:

[0075] 12 g of polytetrahydrofuran, 5 g of hydroxyl-terminated polydimethylsiloxane, and 15 mL of acetone were mixed, 14 g of isophorone diisocyanate, 2 g of 2,2-bis(hydroxymethyl)propionic acid, and 0.2 g of dibutyltin dilaurate were added, the temperature was raised to 70°C and kept warm for 3.5 h, 4 g of pentaerythritol triacrylate and 10 mL of acetone were added, the temperature was raised to 80°C and kept warm for 3.5 h, 3.2 g of benzophenone quaternary ammonium salt compound and 10 mL of acetone were added, the temperature was raised to 90°C and kept warm for 3.5 h, the mixture was cooled to 33°C, 3.1 g of triethanolamine was added, the mixture was kept warm for 25 min, deionized water was added, the mixture was emulsified for 1 h, and the mixture was rotary evaporated to obtain a silicone-modified waterborne polyurethane with a solid content of 29%;

[0076] S4: Spraying the PU coating onto the surface of the pretreated substrate and performing photocuring to obtain an electronic product housing based on the PU coating; the working conditions of the photocuring treatment are: selecting a 1kW high-pressure mercury lamp, a distance of 25cm, and a time of 20s; the photoinitiator is 2,4,6-trimethylbenzoyl-xylylphosphine oxide.

[0077] Example 3: A method for preparing an electronic product housing based on a PU coating, comprising the following steps:

[0078] S1: preparing a silicone coating using epoxy resin, epoxy-terminated silicone, modified zirconium phosphate, and a curing agent;

[0079] The modified zirconium phosphate, epoxy resin, epoxy-terminated silicone and curing agent are compounded in a mass ratio of 2:25:15:5;

[0080] The preparation of silicone coatings includes the following steps:

[0081] (1) Mix 7g of hydroxy silicone oil and 1.1g of 3-(2,3)-glycidoxypropylmethyldimethoxysilane, heat to 88-92℃ and keep warm for 5-6h, and distill under reduced pressure to obtain epoxy-terminated silicone;

[0082] (2) 2 g of modified zirconium phosphate, 25 g of epoxy resin E-51, and 15 g of epoxy-terminated silicone were mixed, heated to 142 °C and kept warm for 3 h, 20 mL of deionized water and 0.14 g of acetic acid were added, and the mixture was kept warm for 4 h. 2 drops of dibutyltin dilaurate were added, and the mixture was kept warm for 5 h. 5 g of curing agent was added, and the mixture was cooled and discharged to obtain a silicone coating;

[0083] The preparation of the modified zirconium phosphate comprises the following steps:

[0084] 1) Mix 21.6 mL of deionized water and 18.4 mL of phosphoric acid, add 4 g of zirconium oxychloride octahydrate, transfer to a hydrothermal autoclave, heat to 200°C and keep warm for 4 h, wash, centrifuge, and dry to obtain α-zirconium phosphate nanosheets;

[0085] 2) Mix 5 mL of 3-(2,3)-glycidoxypropylmethyldimethoxysilane, 80 mL of ethanol, and 20 mL of deionized water, adjust the pH of the solution to 4.1, stir for 2 h, add 1 g of α-zirconium phosphate nanosheets, stir for 24 h, centrifuge, wash, and dry to obtain epoxidized zirconium phosphate;

[0086] 3) Weigh 1.2 g of benzophenone quaternary ammonium salt, 0.7 g of epoxidized zirconium phosphate, and 5 mL of chloroform, mix, add 0.5 g of Amberlyst-15 ion exchange resin, transfer to an ultrasonic water bath, heat to 62°C and hold for 2 h, filter, and rotary evaporate to obtain modified zirconium phosphate;

[0087] The preparation of the benzophenone quaternary ammonium salt compound comprises the following steps:

[0088] A. Mix 0.05 mol of 2,4-dihydroxybenzophenone, 0.07 mol of potassium carbonate, and 50 mL of acetone, add 0.1 mol of dimethylaminochloroethane hydrochloride, raise the temperature to 56°C and maintain for 11 hours, then add dilute hydrochloric acid and NaOH solution in sequence, extract with ether, separate the layers, and dry over anhydrous sodium sulfate to obtain an intermediate preparation;

[0089] B. Mix 1 g of the intermediate preparation and 3 g of bromooctane, heat to 122°C and keep warm for 3 hours, cool, recrystallize from ethyl acetate 5 times, and filter to obtain a benzophenone quaternary ammonium salt compound;

[0090] S2: The substrate is immersed in a 3 wt % ethanol solution of Michaelis acid for acidification, and then an organic silicone coating is sprayed on the surface of the substrate and dried to obtain a pretreated substrate; the substrate is a glass fiber board;

[0091] The working conditions of acidification treatment were: temperature 38 °C, time 2 h;

[0092] S3: Preparation of PU coating using modified zirconium phosphate, silicone-modified waterborne polyurethane, and photoinitiator;

[0093] The composition of the PU coating is, in parts by mass: 5 parts of modified zirconium phosphate, 33 parts of silicone-modified waterborne polyurethane, and 0.2 parts of photoinitiator;

[0094] The preparation of silicone-modified waterborne polyurethane includes the following steps:

[0095] 12 g of polytetrahydrofuran, 5 g of hydroxyl-terminated polydimethylsiloxane, and 15 mL of acetone were mixed, 14 g of isophorone diisocyanate, 2 g of 2,2-bis(hydroxymethyl)propionic acid, and 0.2 g of dibutyltin dilaurate were added, the temperature was raised to 72°C and kept warm for 3 h, 4 g of pentaerythritol triacrylate and 10 mL of acetone were added, the temperature was raised to 82°C and kept warm for 3 h, 3.2 g of benzophenone quaternary ammonium salt compound and 10 mL of acetone were added, the temperature was raised to 92°C and kept warm for 3 h, the mixture was cooled to 35°C, 3.1 g of triethanolamine was added, the mixture was kept warm for 30 min, deionized water was added, the mixture was emulsified for 1 h, and the mixture was rotary evaporated to obtain a silicone-modified waterborne polyurethane with a solid content of 29%;

[0096] S4: Spraying the PU coating onto the surface of the pretreated substrate and performing photocuring to obtain an electronic product housing based on the PU coating; the working conditions of the photocuring treatment are: selecting a 1kW high-pressure mercury lamp, a distance of 25cm, and a time of 20s; the photoinitiator is 2,4,6-trimethylbenzoyl-xylylphosphine oxide.

[0097] Comparative Example 1: Taking Example 3 as the control group, the modified zirconium phosphate was replaced by α-zirconium phosphate nanosheets, and the other processes were normal.

[0098] Comparative Example 2: Example 3 was used as a control group, in which no organosilicon coating was prepared and other processes were normal.

[0099] Comparative Example 3: Taking Example 3 as the control group, no benzophenone quaternary ammonium salt compound was prepared, and the other processes were normal.

[0100] The thickness formed by the silicone coating is 0.1 mm, and the thickness formed by the PU coating is 0.2 mm.

[0101] Sources of raw materials used (for demonstration purposes only):

[0102] Glass fiber board (3mm): Dongguan Aokexing Composite Materials Products Co., Ltd.; Hydroxyl-terminated polydimethylsiloxane (99%): Wuhan Kanos Technology Co., Ltd.; Epoxy resin E-51: Wuhan Penglei Biotechnology Co., Ltd.; Amberlyst-15 ion exchange resin Y52434: Shanghai Yuanye Biotechnology Co., Ltd.; Curing agent 651: Xuzhou Jiabao Runhe New Materials Technology Co., Ltd.; Hydroxyl silicone oil (98%): Hubei Hengjingrui Chemical Co., Ltd.; Polytetrahydrofuran P118599, 3-(2,3)-glycidoxypropylmethyldimethoxysilane G134407, zirconium oxychloride octahydrate Z104931, 2,4-dihydroxy Benzophenone D110121, dimethylaminoethyl chloride hydrochloride D154697, octane bromide B152446, Michaelis acid M110151, isophorone diisocyanate I109582, dibutyltin dilaurate D100274, 2,2-bis(hydroxymethyl)propionic acid D165817, pentaerythritol triacrylate P192936, triethanolamine T431267, 2,4,6-trimethylbenzoyl-xylylphosphine oxide T107643: Aladdin reagent; acetic acid, phosphoric acid, ethanol, chloroform, acetone, dilute hydrochloric acid, NaOH solution, ether, anhydrous sodium sulfate, potassium carbonate, ethyl acetate, analytical grade: Sinopharm reagent.

[0103] Performance test: The shells prepared in the examples and comparative examples were tested:

[0104] Hydrophobicity: Characterized by water contact angle, tested with a 3µL deionized water droplet; UV aging resistance: Determined by gloss loss rate, tested with reference to GB / T9754-2007, with the sample placed in an aging chamber under the following working conditions: relative humidity of 48%, light intensity of 180W / m 2 , temperature 70 ° C, irradiation 2h, spray with deionized water 18min, 60° glossiness was measured every 60h, and the surface gloss loss rate after 2 weeks of irradiation was obtained as (G0-G) / G0×100% (G0-initial glossiness; G-glossiness after aging test); Abrasion resistance: The abrasion medium was AATCC standard cotton cloth, and the abrasion tester was used for testing. The weight was 0.2kg, and a back and forth of 10cm was considered an abrasion cycle. After 100 cycles, the water contact angle was measured again. The difference with the initial water contact angle was less than 1°, including 1°, which was excellent, otherwise it was unqualified; the results are shown in Table 1;

[0105] Table 1

[0106]

[0107] The present invention provides a PU-coated electronic product housing and a preparation method thereof. Through component and process optimization, a glass fiber board or a PC board is used as a substrate, and a silicone coating and a PU coating are sprayed sequentially on the surface of the substrate by spraying. The electronic product housing has an aging-resistant, corrosion-resistant, wear-resistant, and super-hydrophobic surface. In Table 1, / indicates that the item was not tested.

[0108] Comparing Example 3 with Comparative Example 1 and Comparative Example 3, it can be seen that in order to improve the corrosion resistance of the shell and prevent the prepared coating from having problems such as cracks and gaps, the present invention introduces a layered α-zirconium phosphate with high mechanical strength, good acid and alkali resistance, and high thermal stability into the silicone coating and the PU coating as a filler. In order to improve the uniformity of the dispersion of α-zirconium phosphate in the coating, the α-zirconium phosphate is modified with 3-(2,3)-glycidoxypropylmethyldimethoxysilane to prepare epoxidized zirconium phosphate, and then the epoxy-hydroxyl ring is opened and grafted with a benzophenone quaternary ammonium salt compound, wherein the benzophenone quaternary ammonium salt compound is prepared by a two-step process using 2,4-dihydroxy-benzophenone, dimethylaminochloroethane hydrochloride, and bromoalkane as raw materials. While improving the hydrophobicity of the shell, it is given excellent UV resistance, thereby improving the aging resistance of the shell.

[0109] By comparing Example 3 with Comparative Example 2, it can be seen that in order to improve the adhesion between the PU coating and the substrate, the substrate is first acidified, and then a room temperature curable silicone coating is coated on the surface of the substrate. Epoxy-terminated silicone is prepared using hydroxy silicone oil and 3-(2,3)-glycidoxypropylmethyldimethoxysilane. Then, by utilizing the ring-opening polymerization of the epoxy group, it is blended with modified zirconium phosphate and epoxy resin, and polyamide is used as a curing agent to prepare a silicone coating with good flexibility, high toughness and strong adhesion, thereby greatly improving the weather resistance of the casing.

[0110] By comparing Example 3 with Comparative Example 3, it can be seen that the organosilicon-modified waterborne polyurethane is prepared by using polytetrahydrofuran, hydroxyl-terminated polydimethylsiloxane, and isophorone diisocyanate as raw materials, synthesizing a prepolymer under the catalysis of dibutyltin dilaurate, using 2,2-bis(hydroxymethyl)propionic acid as a hydrophilic chain extender, pentaerythritol triacrylate as a photocuring active ingredient, benzophenone quaternary ammonium salt compound as a capping agent, and triethanolamine as a neutralizing agent, and adding deionized water for emulsification to prepare an organosilicon-modified waterborne polyurethane; at the same time, the introduction of benzophenone quaternary ammonium salt compound improves its photocuring rate and effect, thereby improving the antibacterial property, wear resistance, and corrosion resistance of the shell surface, thereby greatly extending the service life of the shell.

[0111] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structural transformations made using the present invention specification under the inventive concept of the present invention, or any direct / indirect application in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing an electronic product housing based on PU coating, characterized in that: The following steps are involved: S1: preparing a silicone coating using epoxy resin, epoxy-terminated silicone, modified zirconium phosphate, and a curing agent; S2: Immersing the substrate in an ethanol solution of Michaelis' acid for acidification treatment, then spraying an organic silicon coating on the surface of the substrate and drying it to obtain a pretreated substrate; S3: Preparation of PU coating using modified zirconium phosphate, silicone-modified waterborne polyurethane, and photoinitiator; S4: spraying the PU coating on the surface of the pretreated substrate and performing light curing to obtain an electronic product housing based on the PU coating; The preparation of the modified zirconium phosphate comprises the following steps: 1) Mix deionized water and phosphoric acid, add zirconium oxychloride octahydrate, transfer to a hydrothermal kettle, heat to 190-200°C and keep warm for 4-5 hours, wash, centrifuge, and dry to obtain α-zirconium phosphate nanosheets; 2) Mix 3-(2,3)-glycidoxypropylmethyldimethoxysilane, ethanol, and deionized water, adjust the pH of the solution to 3.9-4.1, stir for 1-2 hours, add α-zirconium phosphate nanosheets, stir for 22-24 hours, centrifuge, wash, and dry to obtain epoxidized zirconium phosphate; 3) Mix the benzophenone quaternary ammonium salt compound, epoxidized zirconium phosphate, and chloroform, add Amberlyst-15 ion exchange resin, transfer to an ultrasonic water bath, heat to 58-62°C, and maintain for 2-3 hours. Filter and rotary evaporate to obtain modified zirconium phosphate. The preparation of the organosilicon-modified waterborne polyurethane comprises the following steps: Mix polytetrahydrofuran, hydroxyl-terminated polydimethylsiloxane, and acetone, add isophorone diisocyanate, 2,2-bis(hydroxymethyl)propionic acid, and dibutyltin dilaurate, heat to 68-72°C and keep warm for 3-4 hours, add pentaerythritol triacrylate and acetone, heat to 78-82°C and keep warm for 3-4 hours, add benzophenone quaternary ammonium salt compound and acetone, heat to 88-92°C and keep warm for 3-4 hours, cool to 30-35°C, add triethanolamine, keep warm for 20-30 minutes, add deionized water, emulsify for 1 hour, and rotary evaporate to obtain silicone-modified waterborne polyurethane; The preparation of the benzophenone quaternary ammonium salt compound comprises the following steps: A. Mix 2,4-dihydroxybenzophenone, potassium carbonate, and acetone, add dimethylaminoethyl chloride hydrochloride, raise the temperature to 52-56°C and maintain for 11-12 hours, add dilute hydrochloric acid and NaOH solution in sequence, extract with ether, separate the liquids, and add anhydrous sodium sulfate to dry to obtain an intermediate preparation; B. Mix the intermediate preparation and bromooctane, raise the temperature to 118-122°C and keep it for 3-4 hours, cool it, recrystallize it in ethyl acetate 3-5 times, and filter it to obtain a benzophenone quaternary ammonium salt compound.

2. The method for preparing an electronic product housing based on PU coating according to claim 1, characterized in that: The substrate is one of a glass fiber board and a PC board.

3. The method for preparing an electronic product housing based on PU coating according to claim 1, characterized in that: The working conditions of acidification treatment are: temperature 28-38℃, time 2-3h.

4. The method for preparing an electronic product housing based on PU coating according to claim 1, characterized in that: In the preparation of the organosilicon coating, the modified zirconium phosphate, epoxy resin, epoxy-terminated organosilicon and curing agent are compounded in a mass ratio of 2:25:15:

5.

5. The method for preparing an electronic product housing based on PU coating according to claim 1, characterized in that: The preparation of the organosilicon coating comprises the following steps: (1) Mix hydroxy silicone oil and 3-(2,3)-glycidoxypropylmethyldimethoxysilane, heat to 88-92°C and keep warm for 5-6 hours, and distill under reduced pressure to obtain epoxy-terminated silicone; (2) Mix the modified zirconium phosphate, epoxy resin and epoxy-terminated silicone, heat to 138-142°C and keep warm for 3-4 hours, then add deionized water and acetic acid, continue to keep warm for 3-4 hours, add dibutyltin dilaurate, keep warm for 4-5 hours, add curing agent, cool and discharge to obtain silicone coating.

6. The method for preparing an electronic product housing based on PU coating according to claim 1, characterized in that: The composition of the PU coating is, by weight, 1-5 parts of modified zirconium phosphate, 18-33 parts of organosilicon-modified waterborne polyurethane, and 0.1-0.2 parts of photoinitiator.

7. An electronic product housing based on PU coating, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 6.

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