A wear-reducing liquid crystal screen optical film and preparation method thereof

Abstract

The present invention provides a friction-reducing liquid crystal screen optical film and a preparation method thereof, relating to the technical field of optical films. The preparation method comprises the following steps: dissolving polyethylene glycol and silane in toluene, adding dibutyltin dilaurate, vacuumizing and extracting the toluene solvent after refluxing, and the remainder being polyethylene glycol containing terminal alkoxysilane; adding methyltrimethoxysilane, dimethyldimethoxysilane, aminosilane, fluorosilane, and polyethylene glycol containing terminal alkoxysilane to a mixed solvent of ethanol and isopropanol; adding hydrochloric acid solution and glacial acetic acid to the solution, stirring and aging to obtain a sol-gel solution; coating the sol-gel on the optical film, and drying to obtain the friction-reducing liquid crystal screen optical film. The present invention has the beneficial effects of effectively reducing the electrostatic effect generated during the friction process and improving the friction-reducing performance of the liquid crystal screen optical film on the lower polarizer.

Description

Technical Field

[0001] The present invention relates to the technical field of optical films, and in particular to a wear-reducing optical film for liquid crystal screens and a preparation method thereof. Background Art

[0002] Triboelectric charging and frictional wear are both ubiquitous phenomena in natural frictional motion, and they can act simultaneously on the surface of friction materials. During friction, the varying ability of surface atoms to gain or lose electrons generates corresponding charges on the surface. The electrostatic effects caused by these triboelectric charges have widespread applications in various fields. However, they can also adversely affect people's lives and production, and even pose safety risks. For example, triboelectric charges can cause breakdown of electronic and electrical components, and static electricity can cause frictional wear. With the rapid development of the electronics and electrical industry, the hazards of triboelectric charging are becoming increasingly serious.

[0003] Liquid crystal displays (LCDs), crucial components of the electronics and electrical industry, often experience close or contact between the polymer optical films and the lower polarizer due to surface electrostatic attraction. These areas can experience friction and wear from impact or vibration during assembly and transportation of LCD components, impacting the quality of optical imaging and causing significant economic losses to the LCD industry annually. This wear between the optical films and polarizers, caused by electrostatic adsorption, is a critical challenge that the LCD industry urgently needs to address. Regulating the charge generated on the friction surface can control the generation and accumulation of triboelectric charges, reducing the attraction between the optical film and the lower polarizer and the adsorption of tiny particles caused by static electricity accumulation. This is an effective method for eliminating the adverse effects of wear and tear caused by triboelectric charging. Furthermore, polymer optical films in LCDs are typically made from polyacrylate polymers, which possess specific surface microstructures to achieve optical performance. These microstructures can easily scratch the lower polarizer during contact with the LCD, creating wear marks and impacting its optical and other properties. Therefore, improving the surface wear resistance of polymer optical films is also a pressing issue for the LCD display industry.

[0004] How to solve the above technical problems is the subject faced by the present invention. Summary of the Invention

[0005] In order to solve the deficiencies of the prior art, the present invention provides a wear-reducing liquid crystal screen optical film and a preparation method thereof.

[0006] The technical solution adopted by the present invention to solve the technical problem is as follows: the present invention provides a wear-reducing liquid crystal screen optical film and a preparation method thereof. The wear-reducing liquid crystal screen optical film is achieved by applying a sol-gel coating on the optical film. The specific sol-gel coating and the preparation method of the wear-reducing optical film include the following steps:

[0007] A. Preparation of polyethylene glycol containing terminal alkoxysilane:

[0008] Polyethylene glycol and silane in a molar ratio of 1:1 were dissolved in toluene 10 times their mass, and 0.5% of the total mass of dibutyltin dilaurate was added, and refluxed at 115°C for 2 hours;

[0009] The toluene solvent is extracted by vacuum, and the remainder is polyethylene glycol containing terminal alkoxysilane;

[0010] B. Preparation of sol-gel: adding methyltrimethoxysilane, dimethyldimethoxysilane, aminosilane, fluorosilane and polyethylene glycol containing terminal alkoxysilane prepared in step A to a mixed solvent of ethanol and isopropanol;

[0011] adding hydrochloric acid solution and glacial acetic acid to the solution, stirring the mixed solution, and then aging it at room temperature to obtain a sol-gel solution;

[0012] C. Preparation of anti-friction liquid crystal screen optical film: coating the sol-gel on the optical film by dip coating or spray coating, and drying in an oven at 100° C. for 5 hours to obtain the anti-friction liquid crystal screen optical film.

[0013] The average molecular weight of the polyethylene glycol is 200 to 400.

[0014] The silane in step A is one or both of tetramethoxysilane and tetraethoxysilane.

[0015] The aminosilane described in step B is one or more of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, diethylenetriaminopropyltrimethoxysilane, and diethylenetriaminopropyltriethoxysilane.

[0016] The fluorosilane described in step B is one or more of perfluorooctyltriethoxysilane, perfluorooctyltrimethoxysilane, perfluorodecyltrimethoxysilane, and perfluorodecyltriethoxysilane.

[0017] The thickness of the gel coating is 0.5-2 μm.

[0018] The ratio of the amount of aminosilane, fluorosilane and polyethylene glycol containing terminal alkoxysilane to the amount of methyltrimethoxysilane, dimethyldimethoxysilane, aminosilane, fluorosilane and polyethylene glycol containing terminal alkoxysilane is 1:5-1:50.

[0019] The ratio of the amount of aminosilane to the total silane (methyltrimethoxysilane, dimethyldimethoxysilane, aminosilane, fluorosilane and polyethylene glycol containing terminal alkoxysilane) is 1:2-1:20;

[0020] The molar ratio of the fluorosilane to the total silanes (methyltrimethoxysilane, dimethyldimethoxysilane, aminosilane, fluorosilane and polyethylene glycol containing terminal alkoxysilane) is 1:2-1:20;

[0021] The molar ratio of the polyethylene glycol containing terminal alkoxysilane to the total silanes (methyltrimethoxysilane, dimethyldimethoxysilane, aminosilane, fluorosilane and polyethylene glycol containing terminal alkoxysilane) is 1:2-1:20.

[0022] The beneficial effects of the present invention are as follows: the sol-gel system adopted in this scheme is based on fluorine-containing chain siloxane, siloxane containing amino side groups and polyethylene glycol containing terminal alkoxysilane. The synergistic effect of these three components makes the coated optical film show a significant improvement in the friction performance. The fluorine-containing chain siloxane has the high electronegativity and low surface energy characteristics of fluorine atoms, so that the coating surface shows excellent hydrophobicity and low friction coefficient, which not only reduces the direct contact between the LCD screen optical film and the lower polarizer during use, but also effectively prevents friction and wear.

[0023] The introduction of amino-containing siloxane into the sol-gel in this solution effectively counteracts triboelectric charging by forming an opposite charge with the fluorinated siloxane during friction. Triboelectric charging is a key factor in increasing the coefficient of friction between the optical film and the lower polarizer. By suppressing this phenomenon, the optical film exhibits more stable friction performance during use, extending its service life.

[0024] Polyethylene glycol, a material with excellent lubricity, is used in this invention to further enhance the wear-reducing properties of the optical film. The presence of polyethylene glycol segments enables the sol-gel coating to form a lubricating film during friction, reducing the coefficient of friction on the coating surface. This lubrication not only reduces the potential for frictional damage but also ensures that the coated optical film maintains good optical transparency and structural integrity over extended use.

[0025] The sol-gel coating of the present invention has a thickness of 0.5-2 μm, ensuring the coating's anti-friction properties while not affecting the optical performance of the LCD screen. The coating's uniformity and stability are also fully guaranteed. In practical applications, the coating can withstand multiple friction events while maintaining its excellent anti-friction properties. This is of great significance for the long-term stable use of LCD screens.

[0026] Through its innovative sol-gel system design, the present invention not only improves the wear resistance of LCD screen optical films, but also effectively reduces the electrostatic effects generated during friction, enhancing the coating's lubricity and durability. LCD screen optical films coated with this sol-gel coating exhibit improved wear-reducing properties, effectively reducing wear on the lower polarizer during extended use, extending the lifespan of the LCD screen without adversely affecting its optical performance. These advantages give the present invention broad application prospects in the field of liquid crystal display technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a scanning electron microscope image of the anti-friction liquid crystal screen polymer optical film of the present invention.

[0028] Figure 2 This is a scanning electron microscope image of the polarizing plate under the initial liquid crystal screen of the present invention.

[0029] Figure 3 This is a scanning electron microscope image of the polarizer under the liquid crystal display according to Example 1 of the present invention.

[0030] Figure 4 This is a scanning electron microscope image of the polarizer under the liquid crystal screen according to Example 2 of the present invention.

[0031] Figure 5 This is a scanning electron microscope image of the polarizer under the liquid crystal screen of Example 3 of the present invention.

[0032] Figure 6 This is a scanning electron microscope image of the polarizer under the liquid crystal screen according to Example 4 of the present invention.

[0033] Figure 7 This is a scanning electron microscope image of the polarizer under the liquid crystal screen of comparative example 1 of the present invention. DETAILED DESCRIPTION

[0034] In order to clearly illustrate the technical features of this solution, the solution is described below through specific implementation methods.

[0035] Example 1

[0036] This embodiment is a wear-reducing liquid crystal screen optical film and a preparation method thereof, comprising the following steps:

[0037] A. Preparation of polyethylene glycol containing terminal alkoxysilane:

[0038] 0.05 mol polyethylene glycol (average molecular weight 200) and 0.05 mol tetramethoxysilane were dissolved in 176 g toluene, and 0.97 g dibutyltin dilaurate was added, and the mixture was refluxed at 115°C for 2 h.

[0039] The toluene solvent is extracted by vacuum, and the remainder is polyethylene glycol containing terminal alkoxysilane;

[0040] B. Preparation of sol-gel: 0.1 mol methyltrimethoxysilane, 0.02 mol dimethyldimethoxysilane, 0.02 mol diethylenetriaminopropyltrimethoxysilane, 0.02 mol perfluorodecyltrimethoxysilane, and 0.02 mol polyethylene glycol containing terminal alkoxysilane were added to a mixed solvent of 1000 mL ethanol and 50 mL isopropanol;

[0041] To the solution, 0.5 mL of 0.01 mol / L hydrochloric acid solution and 0.2 mL of glacial acetic acid were added. The mixed solution was stirred for 1 hour and then aged at room temperature for 7 days to obtain a sol-gel solution.

[0042] C. Preparation of anti-friction liquid crystal screen optical film: coating the sol-gel on the optical film by dip coating or spray coating, and drying in an oven at 100° C. for 5 hours to obtain the anti-friction liquid crystal screen optical film.

[0043] A friction test is performed on the wear-reducing LCD screen optical film and the polarizing plate under the LCD screen.

[0044] Example 2

[0045] This embodiment is a wear-reducing liquid crystal screen optical film and a preparation method thereof, comprising the following steps:

[0046] A. Preparation of polyethylene glycol containing terminal alkoxysilane:

[0047] 0.05 mol polyethylene glycol (400 average molecular weight) and 0.05 mol tetramethoxysilane were dissolved in 276 g toluene, and 1.38 g dibutyltin dilaurate was added, and the mixture was refluxed at 115 °C for 2 h.

[0048] The toluene solvent is extracted by vacuum, and the remainder is polyethylene glycol containing terminal alkoxysilane;

[0049] B. Preparation of sol-gel: 0.1 mol methyltrimethoxysilane, 0.02 mol dimethyldimethoxysilane, 0.02 mol diethylenetriaminopropyltrimethoxysilane, 0.02 mol perfluorodecyltrimethoxysilane, and 0.02 mol polyethylene glycol containing terminal alkoxysilane were added to a mixed solvent of 1000 mL ethanol and 50 mL isopropanol;

[0050] To the solution, 0.5 mL of 0.01 mol / L hydrochloric acid solution and 0.2 mL of glacial acetic acid were added. The mixed solution was stirred for 1 hour and then aged at room temperature for 7 days to obtain a sol-gel solution.

[0051] C. Preparation of anti-friction liquid crystal screen optical film: coating the sol-gel on the optical film by dip coating or spray coating, and drying in an oven at 100° C. for 5 hours to obtain the anti-friction liquid crystal screen optical film.

[0052] A friction test is performed on the wear-reducing LCD screen optical film and the polarizing plate under the LCD screen.

[0053] Example 3

[0054] This embodiment is a wear-reducing liquid crystal screen optical film and a preparation method thereof, comprising the following steps:

[0055] A. Preparation of polyethylene glycol containing terminal alkoxysilane:

[0056] 0.05 mol polyethylene glycol (average molecular weight 200) and 0.05 mol tetramethoxysilane were dissolved in 176 g toluene, and 0.97 g dibutyltin dilaurate was added, and the mixture was refluxed at 115°C for 2 h.

[0057] The toluene solvent is extracted by vacuum, and the remainder is polyethylene glycol containing terminal alkoxysilane;

[0058] B. Preparation of sol-gel: 0.1 mol methyltrimethoxysilane, 0.02 mol dimethyldimethoxysilane, 0.02 mol N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, 0.02 mol perfluorodecyltrimethoxysilane, and 0.02 mol polyethylene glycol containing terminal alkoxysilane were added to a mixed solvent of 1000 mL ethanol and 50 mL isopropanol;

[0059] To the solution, 0.5 mL of 0.01 mol / L hydrochloric acid solution and 0.2 mL of glacial acetic acid were added. The mixed solution was stirred for 1 hour and then aged at room temperature for 7 days to obtain a sol-gel solution.

[0060] C. Preparation of anti-friction liquid crystal screen optical film: coating the sol-gel on the optical film by dip coating or spray coating, and drying in an oven at 100° C. for 5 hours to obtain the anti-friction liquid crystal screen optical film.

[0061] A friction test is performed on the wear-reducing LCD screen optical film and the polarizing plate under the LCD screen.

[0062] Example 4

[0063] This embodiment is a wear-reducing liquid crystal screen optical film and a preparation method thereof, comprising the following steps:

[0064] A. Preparation of polyethylene glycol containing terminal alkoxysilane:

[0065] 0.05 mol polyethylene glycol (average molecular weight 200) and 0.05 mol tetramethoxysilane were dissolved in 176 g toluene, and 0.97 g dibutyltin dilaurate was added, and the mixture was refluxed at 115°C for 2 h.

[0066] The toluene solvent is extracted by vacuum, and the remainder is polyethylene glycol containing terminal alkoxysilane;

[0067] B. Preparation of sol-gel: 0.1 mol methyltrimethoxysilane, 0.02 mol dimethyldimethoxysilane, 0.02 mol diethylenetriaminopropyltrimethoxysilane, 0.02 mol perfluorooctyltriethoxysilane, and 0.02 mol polyethylene glycol containing terminal alkoxysilane were added to a mixed solvent of 1000 mL ethanol and 50 mL isopropanol;

[0068] To the solution, 0.5 mL of 0.01 mol / L hydrochloric acid solution and 0.2 mL of glacial acetic acid were added. The mixed solution was stirred for 1 hour and then aged at room temperature for 7 days to obtain a sol-gel solution.

[0069] C. Preparation of anti-friction liquid crystal screen optical film: coating the sol-gel on the optical film by dip coating or spray coating, and drying in an oven at 100° C. for 5 hours to obtain the anti-friction liquid crystal screen optical film.

[0070] A friction test is performed on the wear-reducing LCD screen optical film and the polarizing plate under the LCD screen.

[0071] Comparative Example 1

[0072] Comparative Example 1 is a polymer optical film in a liquid crystal display screen without coating.

[0073] A friction test was performed between the polymer optical film in the uncoated LCD display and the polarizer under the LCD display.

[0074] Copper foil is applied to one side of a 4cm x 4cm square LCD screen and a lower polarizer. Copper wire is attached to the foil to form the two triboelectric electrodes. The LCD screen screen and lower polarizer, with copper foil and wire attached, are then mounted on a linear motor. The back-and-forth motion of the linear motor causes the screen and lower polarizer to contact and separate. During this contact and separation process, the triboelectric charge generated on the surface is induced on the copper foil. This charge is then connected to an oscilloscope via the copper wire to produce a triboelectric voltage output. The linear motor operates at a frequency of 5Hz.

[0075] Friction coefficient and wear test method:

[0076] The LCD screen film was cut into 1cm x 1cm squares and fixed to the friction rod of a friction tester. The LCD screen's lower plate was cut into 6cm x 6cm squares and fixed to the friction tester. The friction frequency was 1Hz and the applied load was 3N. The LCD screen squares were rubbed against the lower plate for 30 cycles. The friction coefficient was measured from the friction tester, and the scratch morphology was examined using a scanning electron microscope (SEM).

[0077] Table 1 Friction properties of different samples

[0078] sample Triboelectric voltage output / V Friction coefficient Example 1 5 0.29 Example 2 6 0.30 Example 3 9 0.36 Example 4 10 0.38 Comparative Example 1 63 0.53

[0079] The higher the triboelectric voltage, the more static electricity is generated during the friction process. Compared to the polymer optical film in the LCD display with an uncoated coating, the triboelectric voltage output of the coated LCD optical film is lower, indicating that less static electricity is generated during the friction process.

[0080] Compared with the polymer optical film in the uncoated LCD display, the coated LCD optical film has a lower coefficient of friction, indicating that it has better lubricity.

[0081] Figure 1 The scanning electron microscope photo of the prepared anti-friction liquid crystal screen film is Figure 2 It can be seen that the surface of the unworn lower polarizer of the LCD screen is smooth, while the lower polarizers of the LCD screens of Examples 1 to 4 are slightly worn after friction with the wear-reducing LCD screen film. The degree of wear is significantly lower than the wear caused by the untreated LCD screen film on the lower polarizer. This shows that the wear-reducing LCD screen film has good wear-reducing performance and reduces the degree of wear on the lower polarizer of the LCD screen.

[0082] Technical features not described in the present invention can be achieved through or by adopting existing technologies and will not be described in detail here. Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A method for preparing a wear-reducing liquid crystal screen optical film, characterized in that: The following steps are involved: A. Preparation of polyethylene glycol containing terminal alkoxysilane: Polyethylene glycol and silane in a molar ratio of 1:1 were dissolved in toluene (10 times their mass), and 0.5% of the total mass of dibutyltin dilaurate was added, and refluxed at 115°C for 2 hours; The toluene solvent is extracted by vacuum, and the remainder is polyethylene glycol containing terminal alkoxysilane; The silane is one or both of tetramethoxysilane and tetraethoxysilane; B. Preparing a sol-gel solution: adding methyltrimethoxysilane, dimethyldimethoxysilane, aminosilane, fluorosilane, and the polyethylene glycol containing terminal alkoxysilane prepared in step A to a mixed solvent of ethanol and isopropanol; adding hydrochloric acid solution and glacial acetic acid to the solution, stirring the mixed solution, and then aging it at room temperature to obtain a sol-gel solution; C. Preparation of anti-friction liquid crystal screen optical film: coating the sol-gel solution on the optical film by dip coating or spray coating, and drying in an oven at 100° C. for 5 hours to obtain the anti-friction liquid crystal screen optical film.

2. The method for preparing a wear-reducing liquid crystal screen optical film according to claim 1, characterized in that: The average molecular weight of the polyethylene glycol is 200 to 400.

3. The method for preparing a wear-reducing liquid crystal screen optical film according to claim 1, characterized in that: The aminosilane described in step B is one or more of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, diethylenetriaminopropyltrimethoxysilane, and diethylenetriaminopropyltriethoxysilane.

4. The method for preparing a wear-reducing liquid crystal screen optical film according to claim 1, wherein: The fluorosilane described in step B is one or more of perfluorooctyltriethoxysilane, perfluorooctyltrimethoxysilane, perfluorodecyltrimethoxysilane, and perfluorodecyltriethoxysilane.

5. The method for preparing a wear-reducing liquid crystal screen optical film according to claim 1, characterized in that: The thickness of the sol-gel coating is 0.5-2 μm.

6. The method for preparing a wear-reducing liquid crystal screen optical film according to claim 1, characterized in that: The ratio of the amount of aminosilane, fluorosilane and polyethylene glycol containing terminal alkoxysilane to the amount of methyltrimethoxysilane, dimethyldimethoxysilane, aminosilane, fluorosilane and polyethylene glycol containing terminal alkoxysilane is 1:5-1:

50.

7. The method for preparing a wear-reducing liquid crystal screen optical film according to claim 1, characterized in that: The ratio of the amount of aminosilane to the total amount of silane is 1:2-1:20; The molar ratio of the fluorosilane to the total silane is 1:2-1:20; The molar ratio of the polyethylene glycol containing terminal alkoxysilane to the total silane is 1:2-1:20; The total silanes are methyltrimethoxysilane, dimethyldimethoxysilane, aminosilane, fluorosilane and polyethylene glycol containing terminal alkoxysilane.

8. A friction-reducing liquid crystal screen optical film prepared by the preparation method according to any one of claims 1 to 7.

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