A PMMA visible light filter and a production process thereof

Abstract

The application discloses a PMMA visible light filter and a production process thereof. In one aspect, the application provides a PMMA visible light filter, which comprises a substrate, a grating fixed on the upper surface of the substrate, and a covering layer fixed on the upper part of the substrate and completely covering and wrapping the grating. The material of the substrate and the covering layer is PMMA material, the material of the grating is light-curing light-transmitting resin material mixed with red light filter dye, the grating has a periodic convex structure, the thickness of the grating is 200-400 nm, the duty cycle is 0.75, and the period is 350-360 nm. In another aspect, the application also provides a production process of the PMMA visible light filter. The PMMA visible light filter prepared by the application has relatively low cost, excellent selective transmittance to red light, and relatively high light transmittance.

Description

Technical Field

[0001] This application relates to the field of optical film technology, and in particular to a PMMA visible light filter and a manufacturing process for the PMMA visible light filter. Background Technology

[0002] Liquid crystal displays (LCDs), with their advantages of being thin, lightweight, environmentally friendly, and high-performance, are now widely used in various electronic products such as laptops, mobile phones, monitors, and televisions. Color filters are key materials for achieving color in LCD displays. They are one of the important optical components of LCD devices, significantly affecting their color accuracy, brightness, and contrast. For LCD devices, the three primary color filters are fundamental components, providing pure primary colors and enabling high-precision image display.

[0003] Optical filters are made by adding special dyes to plastic or glass sheets. Red filters only allow red light to pass through, blue filters only allow blue light to pass through, and so on. By adding a layer of special dyes to a transparent plastic or glass substrate, the filter gains selective transmittance, allowing only specific wavelengths of light to pass through. Other wavelengths of light are blocked or absorbed by the filter due to changes in the filter's refractive index caused by the dyes.

[0004] Red visible light filters are one of the three primary color filters, an optical element that filters out other visible stray light to obtain pure red light. The wavelength range of red visible light is 600–700 nm. The optimal transmission wavelength for red filters in liquid crystal displays is 620–660 nm. Red light in this wavelength range has a relatively pure color, effectively avoiding color differences and improving color display accuracy. However, current red filters also have some transmittance to light outside the 620–660 nm wavelength range. The transmittance of this stray light can only be controlled within 30%, which significantly affects the color display accuracy of liquid crystal display devices. Summary of the Invention

[0005] In order to solve at least one of the above-mentioned technical problems and to develop a filter product with relatively low cost, excellent selective transmittance of red light, and relatively high transmittance, this application provides a PMMA visible light filter and its manufacturing process.

[0006] On one hand, this application provides a PMMA visible light filter, including a substrate, a grating fixedly disposed on the upper surface of the substrate, and a cover layer fixedly disposed on the upper part of the substrate, the cover layer completely covering and enclosing the grating; the substrate and the cover layer are made of PMMA material, and the grating is made of photocurable transparent resin material mixed with red light filtering dye; the grating has a periodic outward convex structure, the thickness of the grating is 200-400nm, the duty cycle is 0.75, and the period is 350-360nm.

[0007] Optionally, the PMMA material used for the substrate and the cover layer contains stearic acid and nano-titanium dioxide.

[0008] Optionally, the stearic acid has a mass fraction of 2-4%, and the nano-titanium dioxide has a mass fraction of 4-6%.

[0009] Optionally, the light-curing transparent resin material used in the grating has the following raw material components and mass ratios: 50-56 parts EVA resin, 12-16 parts acrylate, 8-12 parts acrylate oligomer, 4-6 parts nano titanium dioxide, 6-8 parts mixed photoinitiator, and 24-28 parts red light filtering dye.

[0010] Optionally, the mixed photoinitiator includes TPO photoinitiator, 184 photoinitiator and 1173 photoinitiator, wherein the mass ratio of TPO photoinitiator, 184 photoinitiator and 1173 photoinitiator is 2:1:1.

[0011] On the other hand, this application also provides a manufacturing process for the aforementioned PMMA visible light filter, including the following steps:

[0012] S1. PMMA raw materials are processed into PMMA masterbatch and substrates are prepared.

[0013] S2. Cover the substrate in step S1 with a mask, and then use ion beam etching to etch an etching groove on the mask that is perfectly adapted to the grating structure. The etching depth needs to reach the upper surface of the substrate to obtain a mask substrate with etching grooves.

[0014] S3. Mix the raw material components of the light-curing transparent resin material and the red light filter dye, and then shear and stir at high speed until the raw materials are fully mixed to obtain the resin liquid;

[0015] S4. Fill the resin liquid obtained in step S3 into the etching groove of the mask substrate with etching groove obtained in step S2 to obtain a resin-filled mask substrate.

[0016] S5. After photocuring the resin-filled mask substrate obtained in step S4, remove the mask and polish the light-cured transparent resin material pillars to obtain a substrate with a grating.

[0017] S6. After the PMMA masterbatch obtained in step S1 is melted, it is coated onto the upper surface of the substrate with grating obtained in step S5 by coating, and the grating is completely covered. After cooling and cutting, the PMMA visible light filter product is obtained.

[0018] Optionally, in step S2, the etching depth extends to 0–50 nm below the upper surface of the substrate.

[0019] Optionally, in step S3, the rotation speed of the high-speed shear stirring is controlled at 2000-2400 rpm, and the stirring time is controlled at 25-30 min.

[0020] Optionally, in step S5, grinding the light-cured transparent resin material column includes grinding the light-cured transparent resin material column to a height consistent with the grating thickness, and polishing the surface of the light-cured transparent resin material column.

[0021] Optionally, in step S6, the thickness of the coating is controlled to be between 0.2 and 0.5 mm.

[0022] In summary, the present invention has at least one of the following beneficial technical effects:

[0023] 1. The filter of this application has a grating made of photosensitive resin material using mixed red light filtering dyes in the PMMA matrix, which can significantly improve the cutoff performance of the red light filtering dye layer against stray light, and the transmission wavelength can be more accurately controlled within the red light wavelength range, effectively improving the selective transmittance performance of the filter.

[0024] 2. The filter of this application adopts a specific grating structure, which further improves the filtering performance of the filter and the transmittance of stray light can be controlled within 10%.

[0025] 3. The fabrication process of this application is relatively simple, employing a process flow of mask etching, photopolymerization molding, and film coating. Through a simple process, high-precision fabrication of gratings is achieved, and the fabricated filter has high structural precision, excellent quality, and a high yield. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the filter in this application;

[0027] Figure 2 This is a schematic diagram of the preparation process of this application;

[0028] Figure 3 This is a diagram showing the light transmittance test results of the filter in Embodiment 1 of this application;

[0029] Figure 4 This is a diagram showing the transmittance test results of the filter in Comparative Example 1 of this application;

[0030] Figure 5 This is a diagram showing the transmittance test results of the filter in Comparative Example 2 of this application;

[0031] Figure 6 This is a diagram showing the transmittance test results of the filter in Embodiment 11 of this application;

[0032] In the diagram: 1. Substrate, 2. Grating, 3. Cover layer. Detailed Implementation

[0033] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0034] like Figure 1 As shown, this application designs a PMMA visible light filter, including a substrate 1, a grating 2 fixedly disposed on the upper surface of the substrate 1, and a cover layer 3 fixedly disposed on the upper part of the substrate 1, the cover layer 3 completely covering and enclosing the grating 2. The PMMA visible light filter designed in this application adopts a design in which a light-transmitting material is used to enclose the filter grating layer.

[0035] The substrate 1 and the cover layer 3 of this application are made of PMMA material, and the grating 2 is made of photocurable transparent resin material mixed with red light filtering dye.

[0036] The PMMA visible light filter of this application is a red light filter, and the structural parameters of the grating 2 are specifically designed to improve the selective transmittance of red light. The grating 2 of this application has a periodic convex structure, the thickness of the grating 2 is 200-400 nm, the duty cycle is 0.75, and the period is 350-360 nm.

[0037] like Figure 2 As shown, the manufacturing process of the PMMA visible light filter described in this application includes the following steps:

[0038] S1. PMMA raw material is made into PMMA masterbatch and substrate 1 is prepared;

[0039] S2. Cover the substrate 1 in step S1 with a mask plate, and then use ion beam etching to etch an etching groove on the mask plate that is perfectly adapted to the structure of grating 2. The etching depth needs to reach the upper surface of the substrate 1 to obtain a mask substrate with etching grooves.

[0040] S3. Mix the raw material components of the light-curing transparent resin material and the red light filter dye, and then shear and stir at high speed until the raw materials are fully mixed to obtain the resin liquid;

[0041] S4. Fill the resin liquid obtained in step S3 into the etching groove of the mask substrate with etching groove obtained in step S2 to obtain a resin-filled mask substrate.

[0042] S5. After photocuring the resin-filled mask substrate obtained in step S4, remove the mask and polish the light-cured transparent resin material column to obtain a substrate 1 with grating 2.

[0043] S6. After the PMMA masterbatch obtained in step S1 is hot-melted, it is coated onto the upper surface of the substrate 1 with grating 2 obtained in step S5 by coating, and the grating 2 is completely covered. After cooling and cutting, the PMMA visible light filter product is obtained.

[0044] The following are embodiments of this application.

[0045] All raw materials used in the embodiments of this application are commercially available.

[0046] The following are Examples 1 to 4 of this application.

[0047] The filters in Examples 1 to 4 of this application have a substrate 1 thickness of 0.4 mm, a cover layer thickness of 0.8 mm, and a finished filter thickness of 1.2 mm.

[0048] Examples 1 to 4 of this application all use polyurethane acrylate photosensitive resin. The specific mass ratio of each raw material component of the photosensitive resin is as follows: 60 parts of polyurethane acrylate, 22 parts of acrylate, 8 parts of mixed photoinitiator, 10 parts of TMPTA diluent, and 28 parts of red light filter dye. The mixed photoinitiator is prepared by mixing TPO photoinitiator and 184 photoinitiator in a mass ratio of 1:1.

[0049] The PMMA visible light filters in Examples 1 to 4 of this application are all manufactured using the following steps:

[0050] S1. PMMA raw material is made into PMMA masterbatch and injection molded to prepare a 0.4mm thick substrate 1;

[0051] S2. A 5mm thick mask is covered on the substrate 1 in step S1. Then, ion beam etching is used to etch an etching groove on the mask that is perfectly adapted to the structure of the grating 2. The etching depth is 5mm, which just etches through the mask and exposes the substrate 1, thus obtaining a mask substrate with etching grooves.

[0052] S3. Weigh the raw materials of polyurethane acrylate photosensitive resin according to the formula and mix them. Then, shear and stir at 1800 rpm for 1 hour to obtain the resin liquid.

[0053] S4. Fill the etching groove of the mask substrate with etching groove obtained in step S2 with the resin liquid obtained in step S3, and fill it with a thickness of 0.1 mm to obtain a resin-filled mask substrate.

[0054] S5. After the resin-filled mask substrate obtained in step S4 is completely cured by ultraviolet light, the mask is removed. Then, the light-cured transparent resin material column is ground and polished until the thickness reaches the design thickness of the grating 2, and a substrate 1 with grating 2 is obtained.

[0055] S6. After the PMMA masterbatch obtained in step S1 is melted, it is coated onto the upper surface of the substrate 1 with grating 2 obtained in step S5 by coating. The coating thickness is 0.8 mm. After cooling and cutting, a PMMA visible light filter with a thickness of 1.2 mm is obtained.

[0056] Example 1

[0057] In this embodiment, the grating 2 has a thickness of 200nm, a duty cycle of 0.75, and a period of 350nm.

[0058] Example 2

[0059] In this embodiment, the grating 2 has a thickness of 200nm, a duty cycle of 0.75, and a period of 360nm.

[0060] Example 3

[0061] In this embodiment, the grating 2 has a thickness of 400 nm, a duty cycle of 0.75, and a period of 354 nm.

[0062] Example 4

[0063] In this embodiment, the grating 2 has a thickness of 340nm, a duty cycle of 0.75, and a period of 354nm.

[0064] The following are Examples 5 to 8 of this application, which are based on Example 4, but differ in the preparation process.

[0065] Example 5

[0066] The difference between this embodiment and embodiment 4 is that in step S2 of the production process, after etching to a depth of 5mm, etching continues for another 50nm, so that a groove with a depth of 50nm and a shape that is perfectly adapted to the structure of the grating 2 is etched on the upper surface of the substrate 1.

[0067] Example 6

[0068] The difference between this embodiment and embodiment 4 is that in step S2 of the production process, after etching to a depth of 5mm, etching continues for 30nm, so that a groove with a depth of 30nm and a shape that is perfectly adapted to the structure of the grating 2 is etched on the upper surface of the substrate 1.

[0069] Example 7

[0070] The difference between this embodiment and embodiment 6 is that in step S3 of the production process, high-speed shearing and stirring are performed at 2000 rpm for 30 minutes.

[0071] Example 8

[0072] The difference between this embodiment and embodiment 6 is that in step S3 of the production process, high-speed shearing and stirring are performed at 2400 rpm for 25 minutes.

[0073] Comparative Example 1

[0074] A red narrowband interference filter of model LGP, manufactured by Shenzhen Xinzhao Optoelectronic Technology Co., Ltd. and used in high-precision optical instruments, was used as comparative example 1.

[0075] Comparative Example 2

[0076] A dye-type red light glass filter, manufactured by Shenzhen Jiete Optoelectronics Co., Ltd. and used in liquid crystal displays, was used as comparative example 2.

[0077] The filters of Examples 1 to 8 and Comparative Examples 1 to 2 were tested using a spectrophotometer with a detection wavelength of 400 to 1000 nm. The transmittance of light in the wavelength range of 625 to 655 nm and the transmittance of light in the wavelength range of 625 to 655 nm were calculated. The results are shown in Table 1 below.

[0078] Table 1. Test results of filters in Examples 1-8 and comparative examples.

[0079] Example 1 86.3 82.5 Example 2 86.1 82.8 Example 3 87.8 83.7 Example 4 88.2 84.4 Example 5 88.2 84.5 Example 6 88.2 84.4 Example 7 88.5 84.9 Example 8 88.6 84.9 Comparative Example 1 84.7 87.2 Comparative Example 2 71.6 74.2

[0080] This application provides the detection diagrams of Example 1, such as... Figure 3 As shown; the detection images of Comparative Example 1 and Comparative Example 2 are also listed, such as Figure 4 and Figure 5 As shown.

[0081] As can be seen from the data in Table 1, the filters of Examples 1 to 8 of this application have a narrower transmittance wavelength bandwidth compared to the high-precision interference filter of Comparative Example 1. The transmittance of light in the wavelength range of 625-655nm is significantly higher than that of the high-precision interference filter of Comparative Example 1 and much higher than that of the red glass filter of Comparative Example 2. Although the transmittance of light in the wavelength range of 625-655nm of the filters of Examples 1 to 8 of this application is slightly lower than that of the high-precision interference filter of Comparative Example 1, it is much higher than that of the red glass filter of Comparative Example 2. The transmittance is at a similar level to that of the high-precision interference filter of Comparative Example 1.

[0082] pass Figure 3 , Figure 4 and Figure 5 The comparison also shows that the transmittance wavelength bandwidth of the filter in Embodiment 1 of this application is significantly narrower than that of the high-precision interference filter in Comparative Example 1, and even more significantly narrower than that of the red glass filter in Comparative Example 2; while the transmittance is not much different between the filter in Embodiment 1 of this application and the high-precision interference filter in Comparative Example 1, and is significantly higher than that of the red glass filter in Comparative Example 2.

[0083] Therefore, the PMMA visible light filter of this application exhibits excellent selective transmittance for red light and high transmittance. In addition to significantly improving the color display accuracy of liquid crystal display devices and effectively avoiding color errors, the PMMA visible light filter of this application also enhances the brightness of the liquid crystal display device. Furthermore, the PMMA visible light filter of this application is made using low-cost dyes and resins; while the high-precision interference filter of Comparative Example 1 requires the use of rare metals and special materials. The PMMA visible light filter of this application achieves or even surpasses the performance of the high-precision interference filter of Comparative Example 1 while significantly reducing costs.

[0084] The following are Examples 9 to 11 of this application, in which the resin material ratio was optimized and the light transmittance was further increased.

[0085] In Examples 9-11 of this application, EVA photosensitive resin is used; in Examples 9-11 of this application, the thickness of grating 2 is 340nm, the duty cycle is 0.75, and the period is 354nm; in Examples 9-11 of this application, the substrate thickness is 0.4mm and the cover layer thickness is 0.4mm.

[0086] The PMMA visible light filters in Examples 9 to 11 of this application are all manufactured using the following steps:

[0087] S1. PMMA raw material is made into PMMA masterbatch and injection molded into a substrate 1 with a thickness of 0.4 mm;

[0088] S2. A 5mm thick mask is covered on the substrate 1 in step S1. Then, ion beam etching is used to etch an etching groove on the mask that is perfectly adapted to the structure of the grating 2. The etching depth is 5mm, which just etches through the mask and exposes the substrate 1, thus obtaining a mask substrate with etching grooves.

[0089] S3. Weigh and mix the raw materials of EVA photosensitive resin according to the formula, and stir at high speed of 2200 rpm for 30 hours to obtain resin liquid.

[0090] S4. Fill the etching groove of the mask substrate with etching groove obtained in step S2 with the resin liquid obtained in step S3, and fill it with a thickness of 0.01 mm to obtain a resin-filled mask substrate.

[0091] S5. After the resin-filled mask substrate obtained in step S4 is completely cured by ultraviolet light, the mask is removed, and then the light-cured transparent resin material column is ground and polished until the thickness reaches 340nm to obtain the substrate 1 with grating 2.

[0092] S6. After the PMMA masterbatch obtained in step S1 is melted, it is coated onto the upper surface of the substrate 1 with grating 2 obtained in step S5 by coating. The coating thickness is 0.4 mm. After cooling and cutting, the PMMA visible light filter product is obtained.

[0093] Example 9

[0094] The PMMA masterbatch in this embodiment uses the following components and mass ratios of PMMA raw materials: 94 parts PMMA granules, 2 parts stearic acid, and 4 parts nano titanium dioxide.

[0095] The raw material components and their mass ratios of the EVA photosensitive resin in this embodiment are as follows: 50 parts EVA resin, 12 parts acrylate, 8 parts acrylate oligomer, 4 parts nano titanium dioxide, 6 parts mixed photoinitiator, and 24 parts red light filtering dye; the mixed photoinitiator is composed of TPO photoinitiator, 184 photoinitiator and 1173 photoinitiator in a mass ratio of 2:1:1.

[0096] Example 10

[0097] The PMMA masterbatch used in this embodiment has the following composition and mass ratio of PMMA raw materials: 90 parts PMMA granules, 4 parts stearic acid, and 6 parts nano titanium dioxide.

[0098] The raw material components and their mass ratios of the EVA photosensitive resin in this embodiment are as follows: 56 parts EVA resin, 16 parts acrylate, 12 parts acrylate oligomer, 6 parts nano titanium dioxide, 8 parts mixed photoinitiator, and 28 parts red light filtering dye; the mixed photoinitiator is composed of TPO photoinitiator, 184 photoinitiator and 1173 photoinitiator in a mass ratio of 2:1:1.

[0099] Example 11

[0100] The PMMA masterbatch used in this embodiment has the following composition and mass ratio of PMMA raw materials: 90 parts PMMA granules, 4 parts stearic acid, and 6 parts nano titanium dioxide.

[0101] The raw material components and their mass ratios of the EVA photosensitive resin in this embodiment are as follows: 54 parts EVA resin, 14 parts acrylate, 10 parts acrylate oligomer, 6 parts nano titanium dioxide, 6.8 parts mixed photoinitiator, and 26 parts red light filtering dye; the mixed photoinitiator is composed of TPO photoinitiator, 184 photoinitiator and 1173 photoinitiator in a mass ratio of 2:1:1.

[0102] The filters of Examples 9 to 11 of this application were tested, and the results are shown in Table 2 below.

[0103] Table 2. Test results of filters in Examples 9-11

[0104] Example 1 92.1 90.4 Example 2 92.6 91.1 Example 3 93.8 91.6

[0105] This application provides a detection diagram of Example 11, such as... Figure 6 As shown.

[0106] Taking the PMMA visible light filter of Embodiment 11 of this application as an example, according to Table 2 and Figure 6 , with Table 1 and Figure 3 By comparison, it can be seen that the overall performance of the filter in Embodiment 11 of this application is significantly better than that of the filters in Embodiments 1-8. Therefore, as shown in Table 2 and... Figure 6 The results show that after further optimization of the filter material and the dimensions of each layer, the performance of the filter can be significantly improved.

[0107] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A PMMA visible light filter, characterized in that, Includes a substrate (1), on the upper surface of the substrate (1) a grating (2) is fixedly provided, and a cover layer (3) is also fixedly provided on the upper part of the substrate (1), the cover layer (3) completely covers and wraps the grating (2); The substrate (1) and the cover layer (3) are made of PMMA material, and the grating (2) is made of photocurable transparent resin material mixed with red light filtering dye; the grating has a periodic outward convex structure, the thickness of the grating (2) is 200-400nm, the duty cycle is 0.75, and the period is 350-360nm. The PMMA material used in the substrate (1) and the cover layer (3) contains stearic acid and nano titanium dioxide. The stearic acid has a mass fraction of 2-4%, and the nano-titanium dioxide has a mass fraction of 4-6%. The light-curing transparent resin material used in the grating (2) has the following raw material components and mass ratios: 50-56 parts of EVA resin, 12-16 parts of acrylate, 8-12 parts of acrylate oligomer, 4-6 parts of nano titanium dioxide, 6-8 parts of mixed photoinitiator, and 24-28 parts of red light filter dye. The mixed photoinitiator includes TPO photoinitiator, 184 photoinitiator and 1173 photoinitiator, and the mass ratio of TPO photoinitiator, 184 photoinitiator and 1173 photoinitiator is 2:1:1; The manufacturing process of the PMMA visible light filter includes the following steps: S1. PMMA raw materials are made into PMMA masterbatch and substrate is prepared (1); S2. Cover the substrate (1) in step S1 with a mask plate, and then use ion beam etching to etch an etching groove on the mask plate that is perfectly adapted to the grating structure. The etching depth needs to reach the upper surface of the substrate (1) to obtain a mask substrate with etching grooves. S3. Mix the raw material components of the light-curing transparent resin material and the red light filter dye, and then shear and stir at high speed until the raw materials are fully mixed to obtain the resin liquid; S4. Fill the resin liquid obtained in step S3 into the etching groove of the mask substrate with etching groove obtained in step S2 to obtain a resin-filled mask substrate. S5. After photocuring the resin-filled mask substrate obtained in step S4, remove the mask and polish the light-cured transparent resin material column to obtain a substrate (1) with grating (2). S6. After the PMMA masterbatch obtained in step S1 is hot-melted, it is coated onto the upper surface of the substrate (1) with grating (2) obtained in step S5 by coating, and the grating (2) is completely covered. After cooling and cutting, the PMMA visible light filter product is obtained.

2. A PMMA visible light filter according to claim 1, characterized in that, In step S2, the etching depth is 0-50 nm below the upper surface of the substrate (1).

3. A PMMA visible light filter according to claim 1, characterized in that, In step S3, the high-speed shear stirring speed is controlled at 2000-2400 rpm, and the stirring time is controlled at 25-30 min.

4. A PMMA visible light filter according to claim 1, characterized in that, In step S5, grinding the light-curing transparent resin material column includes grinding the light-curing transparent resin material column to a height consistent with the thickness of the grating (2), and polishing the surface of the light-curing transparent resin material column.

5. A PMMA visible light filter according to claim 1, characterized in that, In step S6, the thickness of the coating is controlled between 0.2 and 0.5 mm.

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