Display screen protection film and preparation method thereof

Abstract

The invention discloses a display screen protection film and a preparation method thereof, and relates to the technical field of films. The display screen protection film prepared by the invention comprises modified polyacrylate, modified polysiloxane, modified silicon dioxide, a solvent, a flatting agent and a defoaming agent, and the modified polyacrylate is obtained by grafting polyacrylate with 4-(hydroxymethyl) acetophenone and then reacting with p-hydroxymethylbenzaldehyde; the modified silicon dioxide is prepared by the following steps: reacting pretreated silicon dioxide with 2, 5-dimercaptothiadiazole and octyl chloroacetate, oxidizing, reacting with a piperidyl monomer, and demethylating. The display screen protection film prepared by the invention has good antibacterial, anti-blue-light and anti-ultraviolet properties and mechanical properties.

Description

Technical Field

[0001] The present invention relates to the field of film technology, and specifically to a display screen protective film and a preparation method thereof. Background Art

[0002] A display screen protective film is a thin film attached to the surface of a display device screen, aiming to provide an additional protective layer for the screen to prevent scratches, cracks and daily wear. Due to the widespread use of touch screen devices, fingerprints and grease left by finger touches have become an important factor affecting screen clarity. Therefore, a protective film with hydrophobic properties is needed to reduce this kind of contamination and ensure that the screen always remains clear and clean. Hydrophobic materials can effectively reduce the adhesion ability of water droplets and grease on the film surface, making these contaminants easier to be removed, thus maintaining the cleanliness of the screen.

[0003] On the other hand, with the increasing prevalence of using electronic devices for a long time, the potential harm of blue light to eye health has also attracted wide attention. Blue light is a part of the visible spectrum and has relatively high energy. Prolonged exposure to blue light may cause visual fatigue, dry eyes and even damage to retinal cells. In addition, considering public places and personal hygiene issues, especially in the current complex and changeable global public health situation, the demand for antibacterial functions has become particularly important. To sum up, modern display screen protective films are not only a simple physical barrier, but also products integrating multiple functions such as hydrophobicity, blue light resistance and antibacterial properties, etc., to meet the growing needs of consumers and adapt to changing application scenarios. Summary of the Invention

[0004] The purpose of the present invention is to provide a display screen protective film and a preparation method thereof to solve the problems existing in the prior art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A preparation method of a display screen protective film includes the following preparation steps:

[0007] (1) React polyacrylate and 4-(hydroxymethyl)acetophenone to obtain pre-modified polyacrylate;

[0008] (2) React pre-modified polyacrylate and p-hydroxybenzaldehyde to obtain modified polyacrylate;

[0009] (3) React pretreated silica, 2,5-dimercapto-1,3,4-thiadiazole, octyl chloroacetate and N,N-dimethylformamide to obtain pre-modified silica; oxidize the pre-modified silica with potassium permanganate to obtain sulfonyl silica;

[0010] (4) reacting malondialdehyde dimethyl acetal and 4-methoxypiperidine to obtain a piperidinyl monomer; reacting sulfone silica and a piperidinyl monomer to obtain a modified silica precursor; reacting the modified silica precursor and boron tribromide to obtain modified silica;

[0011] (5) reacting hydrogen-containing silicone oil and allyl polyether to obtain pre-modified polysiloxane; reacting the pre-modified polysiloxane, diphenylmethane diisocyanate, and caprolactam to obtain modified polysiloxane;

[0012] (6) Weigh the following raw materials: 100 parts by mass of modified polyacrylate, 10-12 parts by mass of modified polysiloxane, 15-20 parts by mass of modified silica, 300-350 parts by mass of solvent, 1-2 parts by mass of leveling agent, and 1-2 parts by mass of defoaming agent; mix the above raw materials evenly, apply them on a PET release film, and cure them at 100-120° C. for 1-2 hours to obtain a display screen protective film.

[0013] As an optimization, the preparation method of the pre-modified polyacrylate in step (1) is: polyacrylate, 4-(hydroxymethyl)acetophenone, and toluene are mixed, heated to 100-110° C. and refluxed for 1 hour, dibutyltin dilaurate and a polymerization inhibitor are added, heated to 150-160° C. under nitrogen protection, cooled to room temperature, and washed and dried by reduced pressure distillation to obtain the pre-modified polyacrylate; the mass ratio of polyacrylate, 4-(hydroxymethyl)acetophenone, toluene, dibutyltin dilaurate, and polymerization inhibitor is 1:(0.2-0.3):(20-30):0.01:0.001.

[0014] As an optimization, the preparation method of the modified polyacrylate in step (2) is: pre-modified polyacrylate, p-hydroxymethylbenzaldehyde, boron trifluoride etherate, and tetrahydrofuran are mixed in a mass ratio of 1: (0.3-0.4): (0.15-0.2): (20-30) for 2-3 hours, and then the modified polyacrylate is obtained by vacuum rotary evaporation, filtering, washing, and drying.

[0015] As an optimization, the preparation method of the sulfone-based silica in step (3) is as follows: Mix silica, 3-chloropropyltriethoxysilane, absolute ethanol, and pure water in a mass ratio of 1:(1 - 1.5):(20 - 30):(20 - 30), adjust the pH to 4 - 5 with 60wt% hydrochloric acid, raise the temperature to 110°C, and react under reflux for 4 - 5h. After filtration, washing, and drying, pretreated silica is obtained; Mix the pretreated silica, 2,5-dimercapto-1,3,4-thiadiazole, octyl chloroacetate, N,N-dimethylformamide, and sodium methoxide in a mass ratio of 1:(1.5 - 2.0):(2.0 - 2.5):(30 - 40):(3.0 - 4.0), stir at room temperature for 2h, raise the temperature to 100 - 110°C, and react for 5 - 6h. After filtration, washing, and drying, pre-modified silica is obtained; Mix the pre-modified silica, potassium permanganate, and glacial acetic acid in a mass ratio of 1:(2 - 3):(10 - 12), react for 3 - 4h, add a saturated sodium bisulfite solution with a mass 2 - 3 times that of glacial acetic acid, and after filtration, washing, and drying, sulfone-based silica is obtained.

[0016] As an optimization, the preparation method of the modified silica in step (4) is as follows: Mix malonaldehyde dimethyl acetal, 4-methoxypiperidine, and glacial acetic acid, raise the temperature to 110°C and reflux for 2 - 3h, distill out glacial acetic acid, add pure water with a volume 1 - 2 times that of glacial acetic acid, then add sodium tetrafluoroborate, stir at room temperature for 12h, separate the liquid and extract with dichloromethane, and after washing and concentration, a piperidinyl monomer is obtained; The mass ratio of malonaldehyde dimethyl acetal, 4-methoxypiperidine, glacial acetic acid, pure water, and sodium tetrafluoroborate is 1:(2.1 - 2.5):(20 - 30):(25 - 35):(0.7 - 0.8); Mix the modified silica precursor, the piperidinyl monomer, N,N-dimethylacetamide, and 2,3,4,6,7,8,9,10-octahydropyrimidoazepine in a mass ratio of 1:(2 - 3):(20 - 30):(3 - 4), stir at room temperature for 10 - 12h, and after filtration, washing, and drying, a modified silica precursor is obtained; Mix the modified silica precursor, boron tribromide, and dichloromethane in a mass ratio of 1:(3 - 4):(10 - 12) for 12h, and after filtration, washing, and drying, modified silica is obtained.

[0017] As an optimization, the preparation method of the modified polysiloxane in step (5) is as follows: Mix the hydrogen-containing silicone oil and allyl polyether, heat to 45 - 55 °C under nitrogen protection, add chloroplatinic acid, and then heat to 100 - 110 °C and continue to react for 4 - 5 h. Obtain the pre-modified polysiloxane through rotary evaporation under reduced pressure. Under nitrogen protection, mix the pre-modified polysiloxane and diphenylmethane diisocyanate and heat to 45 - 50 °C, add dibutyltin dilaurate, heat to 75 - 80 °C and react for 3 - 4 h, then cool to 65 - 70 °C to obtain the modified polysiloxane precursor. Add caprolactam and continue to react for 3 - 4 h to obtain the modified polysiloxane; the molar ratio of hydrogen bonds in the hydrogen-containing silicone oil to carbon-carbon double bonds in the allyl polyether is 1:(1.1 - 1.2), and the molar ratio of the pre-modified polysiloxane to diphenylmethane diisocyanate is 1:(2.2 - 2.4); the molar ratio of the modified polysiloxane precursor to caprolactam is 1:(2.2 - 2.4); the mass ratio of the hydrogen-containing silicone oil, chloroplatinic acid, and dibutyltin dilaurate is 1:0.001:0.001.

[0018] As an optimization, the solvent in step (6) is tetrahydrofuran; the leveling agent is BYK-333; the defoaming agent is BYK-066N.

[0019] As an optimization, the polyacrylate is Degalan M 825; the model of the hydrogen-containing silicone oil is RH-H6; the allyl polyether is APEG-1200.

[0020] As an optimization, the reaction process of the modified silica is shown as follows:

[0021]

[0022] The present invention also provides a display screen protective film prepared according to the preparation method of the above display screen protective film.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0024] The display screen protective film prepared by the present invention is obtained by mixing a modified polyacrylate, a modified polysiloxane, a modified silica, a solvent, a leveling agent, and a defoaming agent and then coating and curing on a base film. The modified polyacrylate is obtained by grafting 4-(hydroxymethyl)acetophenone onto the polyacrylate and then reacting with p-hydroxymethylbenzaldehyde; the modified silica is obtained by reacting pretreated silica with 2,5-dimercapto-1,3,4-thiadiazole and octyl chloroacetate, followed by oxidation and then reacting with a piperidyl monomer.

[0025] First, 4-(hydroxymethyl)acetophenone is grafted on the side chain of polyacrylate through an ester exchange reaction, 4-(hydroxymethyl)acetophenone and p-hydroxymethylbenzaldehyde undergo aldehyde-ketone condensation to generate a chalcone structure, and a hydroxyl group is introduced into the side chain; the chalcone structure can effectively absorb ultraviolet rays due to its unique conjugated system, thereby achieving anti-ultraviolet aging performance;

[0026] Secondly, 3-chloropropyltriethoxysilane is used to treat the surface of silica to make the surface of silica contain chlorine groups. 2,5-dimercaptothiadiazole and octyl chloroacetate are polymerized on the surface of silica to form sulfide compounds, and long alkyl chains are introduced on the surface of silica. The alkyl long chains can improve the hydrophobicity of the surface. Under the oxidation of potassium permanganate, the sulfide is converted into sulfone to form a thiadiazole sulfone structure with good antibacterial properties. Then, it reacts with the piperidine monomer to graft a conjugated alkenyl piperidine methoxy group on the methylene group between the thiadiazole sulfone and the ester group. The base structure, thiadiazole sulfone as a strong electron-withdrawing acceptor is connected to the electron-donating group piperidine through a conjugated skeleton, and π-π* transition occurs in the visible light region. Piperidine optimizes the molecular energy level matching by adjusting the conjugation length and the electron donor strength, so that the absorption peak accurately covers the blue light band, ensuring efficient absorption in the blue light band, thereby achieving the effect of resisting blue light, and cooperating with the chalcone structure of the polyacrylate side chain to effectively cover the ultraviolet and blue light regions, enhancing the photostability of the material; boron tribromide can remove the methyl group on the piperidine methoxy group to generate a hydroxyl group;

[0027] Finally, modified polyacrylate, modified polysiloxane, modified silica, solvent, leveling agent and defoaming agent are mixed and coated on the base film for curing to obtain a display screen protective film; the modified polysiloxane end group is blocked by caprolactam, and is unblocked at high temperature to generate isocyanate, which can cross-link with the hydroxyl group of the polyacrylate side chain and the hydroxyl group on the modified silica, thereby enhancing the mechanical properties of the film and also enhancing the hydrophobic properties of the film. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0029] The polyacrylate described in the following examples and comparative examples is Degalan M 825; the inhibitor is PTZ, purchased from Jinan Yunuo Chemical Co., Ltd.; the particle size of the silica is 200 nm; the hydrogen-containing silicone oil model is RH-H6, purchased from Ningbo Runhe High-Tech Materials Co., Ltd.; the allyl polyether is APEG-1200, purchased from Jiangsu Haian Petrochemical Factory; the solvent is tetrahydrofuran; the leveling agent is BYK-333; the defoaming agent is BYK-066N; the PET release film is T60.

[0030] Example 1:

[0031] A method for preparing a display screen protective film, the method for preparing the display screen protective film includes the following preparation steps:

[0032] (1) Mix polyacrylate, 4-(hydroxymethyl)acetophenone, and toluene, heat up to 110 °C and reflux for 1 h, add dibutyltin dilaurate and inhibitor, heat up to 160 °C under nitrogen protection, cool to room temperature, and obtain pre-modified polyacrylate through vacuum distillation, washing, and drying; the mass ratio of polyacrylate, 4-(hydroxymethyl)acetophenone, toluene, dibutyltin dilaurate, and inhibitor is 1:0.2:20:0.01:0.001;

[0033] (2) Mix pre-modified polyacrylate, p-hydroxymethylbenzaldehyde, boron trifluoride diethyl etherate, and tetrahydrofuran in a mass ratio of 1:0.3:0.15:20 and react for 3 h, and obtain modified polyacrylate through vacuum rotary evaporation, filtration, washing, and drying;

[0034] (3) Mix silica, 3-chloropropyltriethoxysilane, absolute ethanol, and pure water in a mass ratio of 1:1:20:20, adjust the pH to 5 with 60 wt% hydrochloric acid, heat up to 110 °C and reflux for 5 h, and obtain pretreated silica through filtration, washing, and drying; mix pretreated silica, 2,5-dimercaptothiadiazole, octyl chloroacetate, N,N-dimethylformamide, and sodium methoxide in a mass ratio of 1:1.5:2.0:30:3.0, stir at room temperature for 2 h, heat up to 110 °C and react for 6 h, and obtain pre-modified silica through filtration, washing, and drying; mix pre-modified silica, potassium permanganate, and glacial acetic acid in a mass ratio of 1:2:10 and react for 4 h, add a saturated sodium bisulfite solution twice the mass of glacial acetic acid, and obtain sulfonyl silica through filtration, washing, and drying;

[0035] (4) malondialdehyde dimethyl acetal, 4-methoxypiperidine, and glacial acetic acid are mixed, heated to 110° C. and refluxed for 3 hours, the glacial acetic acid is distilled off, pure water with a volume of 1 times that of the glacial acetic acid is added, and then sodium tetrafluoroborate is added, stirred at room temperature for 12 hours, separated and extracted with dichloromethane, washed and concentrated to obtain a piperidine monomer; the mass ratio of malondialdehyde dimethyl acetal, 4-methoxypiperidine, glacial acetic acid, pure water, and sodium tetrafluoroborate is 1:2.1:20:25:0.7; the modified silica precursor, piperidine monomer, N,N-dimethylacetamide,

[0036] 2,3,4,6,7,8,9,10-octahydropyrimidoazepine Mix the modified silica precursor, boron tribromide and dichloromethane in a mass ratio of 1:3:10 for 12 hours, stir at room temperature for 12 hours, filter, wash and dry to obtain a modified silica precursor; mix the modified silica precursor, boron tribromide and dichloromethane in a mass ratio of 1:3:10 for 12 hours, filter, wash and dry to obtain a modified silica;

[0037] (5) Mix hydrogen-containing silicone oil and allyl polyether, heat to 55°C under nitrogen protection, add chloroplatinic acid, heat to 110°C and continue to react for 5 hours, and obtain pre-modified polysiloxane by vacuum rotary evaporation; under nitrogen protection, mix pre-modified polysiloxane and diphenylmethane diisocyanate and heat to 50°C, add dibutyltin dilaurate, heat to 80°C and react for 4 hours, cool to 70°C to obtain modified polysiloxane precursor, and add caprolactam, continue to react for 4 hours to obtain modified polysiloxane; the molar ratio of hydrogen bonds in the hydrogen-containing silicone oil and carbon-carbon double bonds in the allyl polyether is 1:1.1, the molar ratio of pre-modified polysiloxane and diphenylmethane diisocyanate is 1:2.2; the molar ratio of the modified polysiloxane precursor and caprolactam is 1:2.2; the mass ratio of the hydrogen-containing silicone oil, chloroplatinic acid, and dibutyltin dilaurate is 1:0.001:0.001;

[0038] (6) Weigh the following raw materials: 100 parts by mass of modified polyacrylate, 10 parts by mass of modified polysiloxane, 15 parts by mass of modified silica, 300 parts by mass of solvent, 1 part by mass of leveling agent, and 1 part by mass of defoaming agent; mix the above raw materials evenly, apply them on a PET release film, and cure them at 120° C. for 2 hours to obtain a display screen protective film.

[0039] Embodiment 2:

[0040] A method for preparing a display screen protective film, the method comprising the following preparation steps:

[0041] (1) Mix polyacrylate, 4-(hydroxymethyl)acetophenone, and toluene, heat up to 105 °C and reflux for 1 h, add dibutyltin dilaurate and inhibitor, heat up to 155 °C under nitrogen protection, cool to room temperature, and obtain pre-modified polyacrylate through vacuum distillation, washing, and drying; the mass ratio of polyacrylate, 4-(hydroxymethyl)acetophenone, toluene, dibutyltin dilaurate, and inhibitor is 1:0.25:25:0.01:0.001;

[0042] (2) Mix pre-modified polyacrylate, p-hydroxybenzaldehyde, boron trifluoride diethyl etherate, and tetrahydrofuran at a mass ratio of 1:0.35:0.17:25 and react for 2.5 h, and obtain modified polyacrylate through vacuum rotary evaporation, filtration, washing, and drying;

[0043] (3) Mix silica, 3-chloropropyltriethoxysilane, absolute ethanol, and pure water at a mass ratio of 1:1.3:25:25, adjust the pH to 4 using 60 wt% hydrochloric acid, heat up to 110 °C and reflux for 4.5 h, and obtain pretreated silica through filtration, washing, and drying; mix pretreated silica, 2,5-dimercaptothiadiazole, octyl chloroacetate, N,N-dimethylformamide, and sodium methoxide at a mass ratio of 1:1.7:2.3:35:3.5, stir at room temperature for 2 h, heat up to 105 °C and react for 5.5 h, and obtain pre-modified silica through filtration, washing, and drying; mix pre-modified silica, potassium permanganate, and glacial acetic acid at a mass ratio of 1:2.5:11 and react for 3.5 h, add a saturated sodium bisulfite solution 2.5 times the mass of glacial acetic acid, and obtain sulfonyl silica through filtration, washing, and drying;

[0044] (4) Mix malonaldehyde dimethyl acetal, 4-methoxypiperidine, and glacial acetic acid, heat up to 110 °C and reflux for 2.5 h, distill out glacial acetic acid, add pure water 1 time the volume of glacial acetic acid, then add sodium tetrafluoroborate, stir at room temperature for 12 h, separate the liquid and extract with dichloromethane, and obtain piperidyl monomer through washing and concentration; the mass ratio of malonaldehyde dimethyl acetal, 4-methoxypiperidine, glacial acetic acid, pure water, and sodium tetrafluoroborate is 1:2.3:25:30:0.75; mix modified silica precursor, piperidyl monomer, N,N-dimethylacetamide,

[0045] 2,3,4,6,7,8,9,10-octahydropyrimidoazepine at a mass ratio of 1:2.5:25:3.5, stir at room temperature for 11 h, and obtain modified silica precursor through filtration, washing, and drying; mix modified silica precursor, boron tribromide, and dichloromethane at a mass ratio of 1:3.5:11 for 12 h, and obtain modified silica through filtration, washing, and drying;

[0046] (5) Mix the hydrogen-containing silicone oil and allyl polyether, heat up to 50 °C under nitrogen protection, add chloroplatinic acid, heat up to 105 °C and continue the reaction for 4.5 h, and obtain the pre-modified polysiloxane by rotary evaporation under reduced pressure; under nitrogen protection, mix the pre-modified polysiloxane and diphenylmethane diisocyanate and heat up to 47 °C, add dibutyltin dilaurate, heat up to 77 °C and react for 3.5 h, cool down to 67 °C to obtain the pre-cursor of the modified polysiloxane, add caprolactam, and continue the reaction for 3.5 h to obtain the modified polysiloxane; the molar ratio of the hydrogen bond in the hydrogen-containing silicone oil to the carbon-carbon double bond in the allyl polyether is 1:1.15, and the molar ratio of the pre-modified polysiloxane to diphenylmethane diisocyanate is 1:2.3; the molar ratio of the pre-cursor of the modified polysiloxane to caprolactam is 1:2.3; the mass ratio of the hydrogen-containing silicone oil, chloroplatinic acid, and dibutyltin dilaurate is 1:0.001:0.001;

[0047] (6) Weigh the following raw materials: by mass, 100 parts of modified polyacrylate, 11 parts of modified polysiloxane, 18 parts of modified silica, 320 parts of solvent, 1.5 parts of leveling agent, and 1.5 parts of defoaming agent; mix the above raw materials evenly, coat them on a PET release film, and cure at 105 °C for 1.5 h to obtain the display screen protection film.

[0048] Example 3:

[0049] A preparation method of a display screen protection film, the preparation method of the display screen protection film includes the following preparation steps:

[0050] (1) Mix the polyacrylate, 4-(hydroxymethyl)acetophenone, and toluene, heat up to 100 °C and reflux for 1 h, add dibutyltin dilaurate and inhibitor, heat up to 150 °C under nitrogen protection, cool to room temperature, and obtain the pre-modified polyacrylate by distillation under reduced pressure, washing, and drying; the mass ratio of polyacrylate, 4-(hydroxymethyl)acetophenone, toluene, dibutyltin dilaurate, and inhibitor is 1:0.3:30:0.01:0.001;

[0051] (2) React the pre-modified polyacrylate, p-hydroxymethylbenzaldehyde, boron trifluoride diethyl etherate, and tetrahydrofuran in a mass ratio of 1:0.4:0.2:30 for 2 h, and obtain the modified polyacrylate by rotary evaporation under reduced pressure, filtration, washing, and drying;

[0052] (3) Mix silicon dioxide, 3-chloropropyltriethoxysilane, absolute ethanol, and pure water in a mass ratio of 1:1.5:30:30, adjust the pH to 5 using 60 wt% hydrochloric acid, raise the temperature to 110 °C, and react under reflux for 4 h. After filtration, washing, and drying, pretreated silicon dioxide is obtained; Mix the pretreated silicon dioxide, 2,5-dimercapto-1,3,4-thiadiazole, octyl chloroacetate, N,N-dimethylformamide, and sodium methoxide in a mass ratio of 1:2.0:2.5:40:4.0, stir at room temperature for 2 h, raise the temperature to 100 °C, and react for 5 h. After filtration, washing, and drying, pre-modified silicon dioxide is obtained; Mix the pre-modified silicon dioxide, potassium permanganate, and glacial acetic acid in a mass ratio of 1:3:12, react for 3 h, add a saturated sodium bisulfite solution three times the mass of glacial acetic acid, and after filtration, washing, and drying, sulfonyl silicon dioxide is obtained;

[0053] (4) Mix malonaldehyde dimethyl acetal, 4-methoxypiperidine, and glacial acetic acid, raise the temperature to 110 °C, and react under reflux for 2 h. Distill out glacial acetic acid, add pure water twice the volume of glacial acetic acid, then add sodium tetrafluoroborate, stir at room temperature for 12 h, separate the liquid and extract with dichloromethane, and after washing and concentration, a piperidinyl monomer is obtained; The mass ratio of malonaldehyde dimethyl acetal, 4-methoxypiperidine, glacial acetic acid, pure water, and sodium tetrafluoroborate is 1:2.5:30:35:0.8; Mix the modified silicon dioxide precursor, piperidinyl monomer, N,N-dimethylacetamide, and 2,3,4,6,7,8,9,10-octahydropyrimidoazepine in a mass ratio of 1:3:30:4, stir at room temperature for 10 h, and after filtration, washing, and drying, a modified silicon dioxide precursor is obtained; Mix the modified silicon dioxide precursor, boron tribromide, and dichloromethane in a mass ratio of 1:4:12 for 12 h, and after filtration, washing, and drying, modified silicon dioxide is obtained;

[0054] (5) Mix hydrogen-containing silicone oil and allyl polyether, raise the temperature to 45 °C under nitrogen protection, add chloroplatinic acid, raise the temperature to 100 °C, and continue to react for 4 h. After rotary evaporation under reduced pressure, a pre-modified polysiloxane is obtained; Under nitrogen protection, mix the pre-modified polysiloxane and diphenylmethane diisocyanate and raise the temperature to 45 °C, add dibutyltin dilaurate, raise the temperature to 75 °C, react for 3 h, cool to 65 °C, to obtain a modified polysiloxane precursor, add caprolactam, and continue to react for 3 h to obtain a modified polysiloxane; The molar ratio of hydrogen bonds in the hydrogen-containing silicone oil to carbon-carbon double bonds in the allyl polyether is 1:1.2, and the molar ratio of the pre-modified polysiloxane to diphenylmethane diisocyanate is 1:2.4; The molar ratio of the modified polysiloxane precursor to caprolactam is 1:2.4; The mass ratio of the hydrogen-containing silicone oil, chloroplatinic acid, and dibutyltin dilaurate is 1:0.001:0.001;

[0055] (6) Weigh the following raw materials: by mass parts, 100 parts of modified polyacrylate, 12 parts of modified polysiloxane, 20 parts of modified silica, 350 parts of solvent, 2 parts of leveling agent, and 2 parts of defoaming agent; mix the above raw materials evenly, coat them on a PET release film, and cure at 100 °C for 1 h to obtain a display screen protection film.

[0056] Comparative Example 1:

[0057] The preparation method of the display screen protection film in Comparative Example 1 is different from that in Example 2 in that silica and polyacrylate are not modified. Specifically, steps (1) to (5) are not included, and step (6) is modified as follows: Weigh the following raw materials: by mass parts, 100 parts of polyacrylate, 11 parts of modified polysiloxane, 18 parts of silica, 320 parts of solvent, 1.5 parts of leveling agent, and 1.5 parts of defoaming agent; mix the above raw materials evenly, coat them on a PET release film, and cure at 105 °C for 1.5 h to obtain a display screen protection film. The remaining steps are the same as those in Example 2.

[0058] Comparative Example 2:

[0059] The preparation method of the display screen protection film in Comparative Example 2 is different from that in Example 2 in that polyacrylate is not modified and sulfonyl group silica is not modified. Specifically, step (4) is not included, and step (6) is modified as follows: Weigh the following raw materials: by mass parts, 100 parts of modified polyacrylate, 11 parts of modified polysiloxane, 18 parts of sulfonyl group silica, 320 parts of solvent, 1.5 parts of leveling agent, and 1.5 parts of defoaming agent; mix the above raw materials evenly, coat them on a PET release film, and cure at 105 °C for 1.5 h to obtain a display screen protection film. The remaining steps are the same as those in Example 2.

[0060] Comparative Example 3:

[0061] The preparation method of the display screen protection film in Comparative Example 3 is different from that in Example 2 in that modified polysiloxane is not added. Specifically, step (6) is modified as follows: Weigh the following raw materials: by mass parts, 100 parts of modified polyacrylate, 18 parts of modified silica, 320 parts of solvent, 1.5 parts of leveling agent, and 1.5 parts of defoaming agent; mix the above raw materials evenly, coat them on a PET release film, and cure at 105 °C for 1.5 h to obtain a display screen protection film. The remaining steps are the same as those in Example 2.

[0062] Test Example 1:

[0063] Test for antibacterial performance:

[0064] Test method: Cut the display screen protective film samples prepared in the examples and comparative examples into a size of 10 cm × 10 cm, soak them in tetrahydrofuran for 12 hours, use a polytetrafluoroethylene scraper to peel the film layer, rinse with deionized water, and then treat them in a vacuum drying oven at 50 °C for 2 h to obtain specimens; according to the standard QB / T2591-2003, then test the antibacterial rate of the samples, and the results are shown in Table 1.

[0065] Table 1

[0066] Antibacterial rate (%) Antibacterial rate (%) Example 1 96.72 Comparative Example 1 13.4 Example 2 97.02 Comparative Example 2 96.31 Example 3 97.31 Comparative Example 3 96.44

[0067] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 1, it can be found that the coating prepared by the present invention has good antibacterial properties.

[0068] The antibacterial properties of Examples 1 to 3 are better than those of Comparative Example 1, indicating that the surface of silica is treated with 3-chloropropyltriethoxysilane to make the surface of silica contain amino groups, and 2,5-dimercapto-1,3,4-thiadiazole and octyl chloroacetate polymerize on the surface of silica to form thioether compounds, and alkyl long chains are introduced on the surface of silica. The alkyl long chains can improve the hydrophobic properties of the surface. Under the oxidation of potassium permanganate, the thioether becomes sulfone, forming a thiadiazole sulfone structure, which has good antibacterial properties.

[0069] Test Example 2:

[0070] Test for blue light blocking and ultraviolet resistance:

[0071] Test method: Use an NS12 high-precision optical transmittance measuring instrument to test the ultraviolet transmittance and blue light blocking rate of the display screen protective film. The results are shown in Table 2.

[0072] Table 2

[0073] Ultraviolet transmittance (%) Blue light blocking rate (%) Example 1 5.3 43.24 Example 2 4.9 43.61 Example 3 4.8 44.07 Comparative Example 1 70.3 17.4 Comparative Example 2 65.4 20.3 Comparative Example 3 5.7 40.3

[0074] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 2, it can be found that the coating prepared by the present invention has good blue light blocking and ultraviolet resistance.

[0075] The blue light and ultraviolet protection performance of Examples 1 to 3 is better than that of Comparative Examples 1 to 2, indicating that 3-chloropropyltriethoxysilane is used to treat the surface of silica, so that the surface of silica contains chlorine groups, 2,5-dimercaptothiadiazole and octyl chloroacetate are polymerized on the surface of silica to form sulfide compounds, and long alkyl chains are introduced on the surface of silica. The long alkyl chains can improve the hydrophobicity of the surface. Under the oxidation of potassium permanganate, the sulfide is converted into sulfone to form a thiadiazole sulfone structure; and then the thiadiazole sulfone and ester are reacted to form a sulfone structure. A conjugated alkenylpiperidinemethoxy structure is grafted onto the methylene group in the middle of the base. The thiadiazole sulfone, as a strong electron-withdrawing acceptor, is connected to the electron-donating group piperidine through a conjugated skeleton, and π-π* transition occurs in the visible light region. Piperidine optimizes the molecular energy level matching by adjusting the conjugation length and the electron donor strength, so that the absorption peak accurately covers the blue light band, ensuring efficient absorption in the blue light band, thereby achieving the effect of anti-blue light, and cooperating with the chalcone structure of the polyacrylate side chain to effectively cover the ultraviolet and blue light regions, enhancing the photostability of the material.

[0076] Test Example 3:

[0077] Mechanical properties test:

[0078] Test method: The hardness of the display screen protective films prepared in the examples and comparative examples was tested according to GB / T 6739--2006. The results are shown in Table 3.

[0079] Hardness Hardness Example 1 5H Comparative Example 1 4H Example 2 6H Comparative Example 2 4H Example 3 6H Comparative Example 3 3H

[0080] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 3, it can be found that the coating prepared by the present invention has good mechanical properties.

[0081] The mechanical properties of Examples 1 to 3 are better than those of Comparative Examples 1 to 3, indicating that the modified polyacrylate, modified polysiloxane, modified silica, solvent, leveling agent, and defoaming agent are mixed and coated on the base film and cured to obtain a display screen protective film; the terminal groups of the modified polysiloxane are blocked by caprolactam, and are deblocked at high temperature to generate isocyanate, which can cross-link with the hydroxyl groups on the side chains of the polyacrylate and the hydroxyl groups on the modified silica, thereby enhancing the mechanical properties of the film.

[0082] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for preparing a display screen protection film, characterized in that, It includes the following preparation steps: (1) React polyacrylate with 4-(hydroxymethyl)acetophenone to obtain pre-modified polyacrylate; (2) React the pre-modified polyacrylate with p-hydroxybenzaldehyde to obtain modified polyacrylate; (3) React pretreated silica, 2,5-dimercapto-1,3,4-thiadiazole, octyl chloroacetate, and N,N-dimethylformamide to obtain pre-modified silica; oxidize the pre-modified silica with potassium permanganate to obtain sulfonyl silica; (4) React malonaldehyde dimethyl acetal with 4-methoxypiperidine to obtain a piperidinyl monomer; react the sulfonyl silica with the piperidinyl monomer to obtain a modified silica precursor; react the modified silica precursor with boron tribromide to obtain modified silica; (5) React hydrogen-containing silicone oil with allyl polyether to obtain pre-modified polysiloxane; react the pre-modified polysiloxane with diphenylmethane diisocyanate and caprolactam to modify the polysiloxane; (6) Weigh the following raw materials: by mass, 100 parts of modified polyacrylate, 10 - 12 parts of modified polysiloxane, 15 - 20 parts of modified silica, 300 - 350 parts of solvent, 1 - 2 parts of leveling agent, and 1 - 2 parts of defoaming agent; mix the above raw materials evenly, coat them on a PET release film, and cure at 100 - 120 °C for 1 - 2 h to obtain a display screen protection film.

2. The preparation method of a display screen protection film according to claim 1, characterized in that, The preparation method of the pre-modified polyacrylate in step (1) is as follows: mix polyacrylate, 4-(hydroxymethyl)acetophenone, and toluene, heat to 100 - 110 °C and reflux for 1 h, add dibutyltin dilaurate and inhibitor, heat to 150 - 160 °C under nitrogen protection, cool to room temperature, and obtain the pre-modified polyacrylate through vacuum distillation, washing, and drying; the mass ratio of polyacrylate, 4-(hydroxymethyl)acetophenone, toluene, dibutyltin dilaurate, and inhibitor is 1:(0.2 - 0.3):(20 - 30):0.01:0.

001.

3. The preparation method of a display screen protection film according to claim 1, characterized in that, The preparation method of the modified polyacrylate in step (2) is as follows: mix the pre-modified polyacrylate, p-hydroxybenzaldehyde, boron trifluoride diethyl etherate, and tetrahydrofuran in a mass ratio of 1:(0.3 - 0.4):(0.15 - 0.2):(20 - 30) and react for 2 - 3 h, and obtain the modified polyacrylate through vacuum rotary evaporation, filtration, washing, and drying.

4. The preparation method of a display screen protection film according to claim 1, wherein, The preparation method of the sulfone group silica in step (3) is as follows: Mix silica, 3-chloropropyltriethoxysilane, absolute ethanol, and pure water according to a mass ratio of 1:(1 - 1.5):(20 - 30):(20 - 30), adjust the pH to 4 - 5 using 60wt% hydrochloric acid, raise the temperature to 110°C, and reflux for 4 - 5 hours. After filtration, washing, and drying, obtain pretreated silica; Mix the pretreated silica, 2,5-dimercapto-1,3,4-thiadiazole, octyl chloroacetate, N,N-dimethylformamide, and sodium methoxide according to a mass ratio of 1:(1.5 - 2.0):(2.0 - 2.5):(30 - 40):(3.0 - 4.0), stir at room temperature for 2 hours, raise the temperature to 100 - 110°C, and react for 5 - 6 hours. After filtration, washing, and drying, obtain pre-modified silica; Mix the pre-modified silica, potassium permanganate, and glacial acetic acid according to a mass ratio of 1:(2 - 3):(10 - 12), react for 3 - 4 hours, add a saturated sodium bisulfite solution with a mass 2 - 3 times that of glacial acetic acid, and after filtration, washing, and drying, obtain sulfone group silica.

5. The preparation method of a display screen protection film according to claim 1, characterized in that, The preparation method of the modified silica described in step (4) is as follows: Mix malonaldehyde dimethyl acetal, 4-methoxypiperidine, and glacial acetic acid, heat up to 110 °C and reflux for 2 - 3 h, distill out glacial acetic acid, add pure water with a volume 1 - 2 times that of glacial acetic acid, then add sodium tetrafluoroborate, stir at room temperature for 12 h, separate the liquid and extract with dichloromethane, and obtain the piperidyl monomer after washing and concentration; the mass ratio of malonaldehyde dimethyl acetal, 4-methoxypiperidine, glacial acetic acid, pure water, and sodium tetrafluoroborate is 1:(2.1 - 2.5):(20 - 30):(25 - 35):(0.7 - 0.8); Mix the modified silica precursor, piperidyl monomer, N,N-dimethylacetamide, and 2,3,4,6,7,8,9,10-octahydropyrimidoazepine Mix them in a mass ratio of 1:(2 - 3):(20 - 30):(3 - 4), stir at room temperature for 10 - 12 h, and obtain the modified silica precursor after filtration, washing, and drying; Mix the modified silica precursor, boron tribromide, and dichloromethane in a mass ratio of 1:(3 - 4):(10 - 12) for 12 h, and obtain the modified silica after filtration, washing, and drying.

6. The preparation method of a display screen protection film according to claim 1, wherein, The preparation method of the modified polysiloxane in step (5) is as follows: Mix hydrogen-containing silicone oil and allyl polyether, raise the temperature to 45 - 55°C under nitrogen protection, add chloroplatinic acid, raise the temperature to 100 - 110°C, and continue to react for 4 - 5 hours. Obtain pre-modified polysiloxane by rotary evaporation under reduced pressure; Under nitrogen protection, mix the pre-modified polysiloxane and diphenylmethane diisocyanate and raise the temperature to 45 - 50°C, add dibutyltin dilaurate, raise the temperature to 75 - 80°C, and react for 3 - 4 hours. Cool down to 65 - 70°C to obtain a modified polysiloxane precursor, add caprolactam, and continue to react for 3 - 4 hours to obtain the modified polysiloxane; The molar ratio of hydrogen bonds in the hydrogen-containing silicone oil to carbon-carbon double bonds in the allyl polyether is 1:(1.1 - 1.2), and the molar ratio of the pre-modified polysiloxane to diphenylmethane diisocyanate is 1:(2.2 - 2.4); The molar ratio of the modified polysiloxane precursor to caprolactam is 1:(2.2 - 2.4); The mass ratio of the hydrogen-containing silicone oil, chloroplatinic acid, and dibutyltin dilaurate is 1:0.001:0.

001.

7. The preparation method of a display screen protection film according to claim 1, wherein, The solvent in step (6) is tetrahydrofuran; The leveling agent is BYK-333; The defoaming agent is BYK-066N.

8. The preparation method of a display screen protection film according to claim 1, characterized in that, The polyacrylate is Degalan M 825; The model of the hydrogen-containing silicone oil is RH-H6; The allyl polyether is APEG-1200.

9. A display screen protective film prepared by the preparation method of the display screen protective film according to any one of claims 1 - 8.

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