A TAC composite film and a preparation method thereof
By introducing thiol-esterified cellulose and alkenyl quaternized cellulose into the TAC composite film, the chemical bonding force between the base film and the coating is enhanced, solving the problem of insufficient interlayer adhesion of the TAC composite film and achieving high light transmittance and excellent mechanical properties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI JIGUANG NEW MATERIALS CO LTD
- Filing Date
- 2026-03-13
- Publication Date
- 2026-05-29
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of optical film technology, specifically relating to a TAC composite film and its preparation method. Background Technology
[0002] Optical TAC film (cellulose triacetate film) is an important raw material in the liquid crystal display industry. It is mainly used as a protective film for polarizers in LCD panels and has good light uniformity, transparency, acid and alkali resistance and UV resistance.
[0003] TAC film is typically laminated to both sides of the PVA polarizing film. On one hand, the TAC film acts as a support for the PVA film, preventing it from shrinking when stretched. On the other hand, the TAC film protects the PVA film from moisture, ultraviolet radiation, and other external substances, ensuring the polarizer's environmental weather resistance. Compared to the inner TAC film, the outer TAC film obviously needs to provide better protection; therefore, functionalization of the TAC film is necessary.
[0004] The preparation method of TAC functional film involves coating a functionalized coating liquid onto a TAC base film to form a functionalized coating. However, simple physical coating is difficult to ensure strong interfacial adhesion between layers, which leads to a decrease in the optical performance of the TAC substrate itself. Therefore, enhancing the interfacial adhesion of the composite structure of TAC functional composite film is crucial to ensuring the overall performance of the film. Summary of the Invention
[0005] The purpose of this invention is to provide a TAC composite film and its preparation method, which can solve the problem of weak interlayer adhesion of TAC composite films in the prior art.
[0006] The objective of this invention can be achieved through the following technical solutions: A TAC composite membrane includes a modified TAC base film and a functional protective coating; The modified TAC-based film was prepared by casting a cellulose triacetate solution. The cellulose triacetate solution comprises the following raw materials by mass parts: 20 parts cellulose triacetate, 1-2 parts thiolated cellulose, 0.1-0.3 parts plasticizer, 0.1-0.4 parts UV absorber, and 80-100 parts mixed solvent; The functional protective coating is obtained by applying a coating slurry and then photocuring it. The coating slurry comprises the following raw materials by weight: The composition consists of 30 parts of light-curable acrylate prepolymer, 4-8 parts of alkenyl quaternized cellulose, 0.5-1.5 parts of photoinitiator, and 40-50 parts of solvent.
[0007] This invention simultaneously optimizes the formulations of the base film and the coating. During the preparation of the base film, thiol-esterified cellulose is added to the raw materials, introducing thiol groups into the cellulose molecular chain. This provides crosslinking active groups for subsequent bonding with substances in the coating. The coating slurry uses photocurable acrylic prepolymer as the main component, with the addition of alkenyl quaternized cellulose as an auxiliary component. On the one hand, the cellulose molecular chain structure of alkenyl quaternized cellulose can improve the affinity between the coating and the base film. On the other hand, alkenyl quaternized cellulose introduces unsaturated alkenyl and quaternary ammonium salt structures, enabling it to participate in the photocuring crosslinking reaction while possessing the properties of an organic antistatic agent. The crosslinking networks of the base film and the coating are tightly bonded through the reaction of thiol groups and double bonds.
[0008] Furthermore, the thickness of the modified TAC base film is 40-60 μm; The thickness of the functional protective coating is 4-6 μm.
[0009] Furthermore, the preparation steps of the thiolated esterified cellulose are as follows: A1. Cellulose introduces carboxyl groups through an oxidation reaction to form oxidized cellulose. A toluene-water mixed solvent is prepared, and oxidized cellulose and ethylenedimerol are added to the mixed solvent. A2. Add concentrated sulfuric acid dropwise. After the addition is complete, heat to 80-90℃, stir for 6-8 hours, cool to room temperature, filter, wash and dry to obtain mercapto-esterified cellulose.
[0010] Furthermore, the oxidized cellulose is prepared by TEMPO oxidation; the carboxyl content of the oxidized cellulose is 1.0-2.0 mmol / g.
[0011] Furthermore, the mass ratio of toluene to water in the toluene-water mixed solvent is 3-5:1.
[0012] Furthermore, the mass ratio of oxidized cellulose to ethylenedimerol is 1:0.3-0.8; the ratio of oxidized cellulose to mixed solvent is (3g-4g):100mL.
[0013] Furthermore, the concentration of the concentrated sulfuric acid is 1.0M, and the concentrated sulfuric acid accounts for 2-3% of the volume of the mixed solvent.
[0014] In the above preparation, the primary hydroxyl group at the C6 position of oxidized cellulose is oxidized to a carboxyl group. Sulfuric acid is used as an acid catalyst to promote the reaction between the carboxyl group on the oxidized cellulose and the thiol group at the end of the ethylenedimerol to form a thioester. The resulting thiol-esterified cellulose contains a thiol group at the end. The thiol group is a highly active group that can react with double bonds, resulting in a chemical bond between the base film and the coating, thus enhancing the interfacial bonding force.
[0015] Further, the plasticizer is at least one selected from triphenyl phosphate, biphenyl diphenyl phosphate, dimethyl phthalate, and diethyl phthalate; The ultraviolet absorber is at least one of UV326, UV327 and UV328.
[0016] Further, the mixed solvent is a mixture of dichloromethane and methanol, with a mass ratio of dichloromethane to methanol of (90-92):(8-10).
[0017] Furthermore, the photocurable acrylate prepolymer is at least one of polyurethane acrylate, polyester acrylate, and epoxy acrylate.
[0018] Furthermore, the preparation steps of the alkenyl quaternized cellulose are as follows: B1. Add cellulose to a 10-20 wt% sodium hydroxide solution, sonicate for 5-10 min, stir at room temperature for 3-4 h, and collect the pretreated cellulose after filtration. B2. Add 10-20wt% sodium hydroxide solution and epichlorohydrin to the pretreated cellulose, stir and react at 60-70℃ for 6-8h, filter and dry to obtain epoxidized cellulose; B3. Add dimethylallylamine isopropanol solution to epoxidized cellulose, stir and react at 40-50℃ for 6-12h, filter, wash and vacuum dry to obtain alkenyl quaternized cellulose.
[0019] Furthermore, the ratio of cellulose to sodium hydroxide solution is (10g-20g): 250mL.
[0020] Further, in step B2, the ratio of the pretreated cellulose, sodium hydroxide solution and epichlorohydrin is (10-20g): 250mL: 250mL.
[0021] Furthermore, the concentration of dimethylallylammonium in the dimethylallylammonium isopropanol solution is 20-40 wt%. The ratio of the epoxidized cellulose to the dimethylallyl ammonium isopropanol solution is (10-20) g: 250 mL.
[0022] In the above preparation process, cellulose is first treated with an alkaline solution to break intermolecular hydrogen bonds, exposing a large number of hydroxyl groups. Epichlorohydrin then undergoes a substitution reaction with cellulose, grafting epoxy groups onto the cellulose molecular chain. Subsequently, the epoxy groups on the epoxidized cellulose undergo a ring-opening reaction with dimethylallylamine to generate cellulose containing allyl and quaternary ammonium groups. The quaternary ammonium group component in the alkenyl quaternized cellulose can improve the antistatic properties of the composite film, and the unsaturated double bonds participate in the photocuring reaction, bonding with the thiol groups of the base film and improving the adhesion of the coating to the base film surface.
[0023] Furthermore, the photoinitiator is at least one of 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methyl-1-phenyl-1-propanone.
[0024] Furthermore, the solvent is at least one selected from ethanol, isopropanol, propanol, and ethyl acetate.
[0025] The present invention also provides a method for preparing a TAC composite membrane, which is used to prepare the TAC composite membrane as described above, comprising the following steps: Step 1: Prepare the raw materials for the cellulose triacetate solution according to the proportion. Add cellulose triacetate, mercapto-esterified cellulose, plasticizer and UV absorber to the mixed solvent, stir evenly to obtain the cellulose triacetate solution, and after degassing, cast into a film to obtain the modified TAC base film. Step 2: Prepare the raw materials for the coating slurry according to the proportion. Add the photocurable acrylate prepolymer, alkenyl quaternized cellulose and photoinitiator to the solvent and stir evenly to obtain the coating slurry. Apply the coating slurry to the surface of the modified TAC base film, heat and dry and UV cure to form a functional protective coating, and obtain the TAC composite film.
[0026] The beneficial effects of this invention are: (1) The present invention provides a TAC composite membrane comprising a modified TAC base film and a functional protective coating. The formulation is optimized based on the triacetate cellulose component of the base film and the photocuring characteristics of the coating. Thiol-esterified cellulose is added to the base film and alkenyl quaternized cellulose is added to the coating. The interfacial bonding force is enhanced through the chemical interaction between the base film and the coating, ensuring that the composite membrane has good optical performance, improving the protective durability of the coating, and extending the service life of the composite membrane.
[0027] (2) The present invention designs and prepares thiol esterified cellulose, modifies the cellulose material and adds it to the base film. It can be well compatible with the original component cellulose triacetate and dispersed evenly. It can also give the base film thiol reaction sites. The thiol and double bond can react rapidly under photocuring conditions to form stable thioether bonds. There is a strong interfacial bonding force between the base film and the coating. The added thiol esterified cellulose will not precipitate after film formation, causing haze increase or yellowing. It maintains the high light transmittance of the TAC composite film and meets the optical property requirements of optical film.
[0028] (3) The present invention designs and prepares alkenyl quaternized cellulose. While introducing double bonds into the cellulose molecular chain, quaternary ammonium cations are also introduced. Adding alkenyl quaternized cellulose to the coating can make the coating and base film components have better affinity and higher bonding force. Alkenyl quaternized cellulose can participate in the photocuring crosslinking reaction of the coating components to form a dense crosslinking network. The rigid skeleton of cellulose is combined with the flexible segments of acrylate to give the coating excellent mechanical properties and wear resistance. The quaternary ammonium cations are dispersed in the coating system, which makes the coating have antistatic properties and effectively prevents static electricity accumulation and dust adsorption. Detailed Implementation
[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0030] Preparation Example
[0031] Preparation Example 1
[0032] Preparation of thiol-esterified cellulose: A1. Weigh cellulose and add it to deionized water at a concentration of 10 g / L. Stir to disperse and obtain a cellulose dispersion. Add TEMPO reagent, NaBr and 8 wt% NaClO solution. The TEMPO reagent is 3% of the mass of cellulose, the NaBr is 2.5 times the mass of cellulose, and the NaClO solution is 20% of the volume of the cellulose dispersion. Then add 0.1 M sodium hydroxide solution to adjust the pH of the system to 10.0. Stir and react for 6 h. After dialyzing, freeze dry to obtain oxidized cellulose with a carboxyl content of 1.13 mmol / g.
[0033] A2. Prepare a toluene-water mixed solvent with a toluene-water mass ratio of 4:1. Add oxidized cellulose and ethylenedimerol to the mixed solvent. The ratio of oxidized cellulose to the mixed solvent is 3.5g:100mL, and the mass ratio of oxidized cellulose to ethylenedimerol is 1:0.5.
[0034] A3. Add 1.0M concentrated sulfuric acid dropwise, with the concentrated sulfuric acid being 2.5% of the volume of the mixed solvent. After the addition is complete, heat to 85℃, stir for 7 hours, cool to room temperature, filter, wash with acetone and ethanol, and dry in a 40℃ oven for 4 hours to obtain mercapto-esterified cellulose.
[0035] Preparation Example 2
[0036] Preparation of thiol-esterified cellulose: A1. Weigh cellulose and add it to deionized water at a concentration of 10 g / L. Stir to disperse and obtain a cellulose dispersion. Add TEMPO reagent, NaBr and 8 wt% NaClO solution. The TEMPO reagent is 3% of the mass of cellulose, the NaBr is 2.5 times the mass of cellulose, and the NaClO solution is 20% of the volume of the cellulose dispersion. Then add 0.1 M sodium hydroxide solution to adjust the pH of the system to 10.0. Stir and react for 6 h. After dialyzing, freeze dry to obtain oxidized cellulose with a carboxyl content of 1.13 mmol / g.
[0037] A2. Prepare a toluene-water mixed solvent with a toluene-water mass ratio of 4:1. Add oxidized cellulose and ethylenedimerol to the mixed solvent. The ratio of oxidized cellulose to the mixed solvent is 3.5g:100mL, and the mass ratio of oxidized cellulose to ethylenedimerol is 1:0.3.
[0038] A3. Add 1.0M concentrated sulfuric acid dropwise, with the concentrated sulfuric acid being 2% of the volume of the mixed solvent. After the addition is complete, heat to 85℃, stir for 7 hours, cool to room temperature, filter, wash with acetone and ethanol, and dry in a 40℃ oven for 4 hours to obtain mercapto-esterified cellulose.
[0039] Preparation Example 3
[0040] Preparation of thiol-esterified cellulose: A1. Weigh cellulose and add it to deionized water at a concentration of 10 g / L. Stir to disperse and obtain a cellulose dispersion. Add TEMPO reagent, NaBr and 8 wt% NaClO solution. The TEMPO reagent is 3% of the mass of cellulose, the NaBr is 2.5 times the mass of cellulose, and the NaClO solution is 20% of the volume of the cellulose dispersion. Then add 0.1 M sodium hydroxide solution to adjust the pH of the system to 10.0. Stir and react for 6 h. After dialyzing, freeze dry to obtain oxidized cellulose with a carboxyl content of 1.13 mmol / g.
[0041] A2. Prepare a toluene-water mixed solvent with a toluene-water mass ratio of 4:1. Add oxidized cellulose and ethylenedimerol to the mixed solvent. The ratio of oxidized cellulose to the mixed solvent is 3.5g:100mL, and the mass ratio of oxidized cellulose to ethylenedimerol is 1:0.8.
[0042] A3. Add 1.0M concentrated sulfuric acid dropwise, with the concentrated sulfuric acid being 3% of the volume of the mixed solvent. After the addition is complete, heat to 85℃, stir for 7 hours, cool to room temperature, filter, wash with acetone and ethanol, and dry in a 40℃ oven for 4 hours to obtain mercapto-esterified cellulose.
[0043] Preparation Example 4
[0044] Preparation of alkenyl quaternized cellulose: B1. Add cellulose to a 20wt% sodium hydroxide solution at a ratio of 10g:250mL, sonicate for 8min, stir at room temperature for 3h, and collect the pretreated cellulose after filtration.
[0045] B2. Add 10wt% sodium hydroxide solution and epichlorohydrin to the pretreated cellulose. The ratio of pretreated cellulose, sodium hydroxide solution and epichlorohydrin is 10g:250mL:250mL. Stir and react at 65℃ for 8h. After filtration, dry at 80℃ for 6h to obtain epoxidized cellulose.
[0046] B3. Prepare a dimethylallylamine isopropanol solution with a dimethylallylamine concentration of 35 wt%. Add the dimethylallylamine isopropanol solution to the epoxidized cellulose. The ratio of epoxidized cellulose to dimethylallylamine isopropanol solution is 15 g: 250 mL. Stir the reaction at 45 °C for 10 h. After filtration, wash the cellulose sequentially with anhydrous ethanol, deionized water, 0.1 M sodium hydroxide solution, and 0.1 M hydrochloric acid solution. Finally, rinse with deionized water and dry under vacuum at 60 °C for 4 h to obtain alkenyl quaternized cellulose.
[0047] Preparation Example 5
[0048] Preparation of alkenyl quaternized cellulose: B1. Add cellulose to a 20wt% sodium hydroxide solution at a ratio of 10g:250mL, sonicate for 8min, stir at room temperature for 3h, and collect the pretreated cellulose after filtration.
[0049] B2. Add 10wt% sodium hydroxide solution and epichlorohydrin to the pretreated cellulose. The ratio of pretreated cellulose, sodium hydroxide solution and epichlorohydrin is 10g:250mL:250mL. Stir and react at 65℃ for 8h. After filtration, dry at 80℃ for 6h to obtain epoxidized cellulose.
[0050] B3. Prepare a dimethylallylamine isopropanol solution with a dimethylallylamine concentration of 30 wt%. Add the dimethylallylamine isopropanol solution to the epoxidized cellulose. The ratio of epoxidized cellulose to dimethylallylamine isopropanol solution is 20 g: 250 mL. Stir the reaction at 45 °C for 10 h. After filtration, wash the cellulose sequentially with anhydrous ethanol, deionized water, 0.1 M sodium hydroxide solution, and 0.1 M hydrochloric acid solution. Finally, rinse with deionized water and dry under vacuum at 60 °C for 4 h to obtain alkenyl quaternized cellulose.
[0051] Preparation Example 6
[0052] Preparation of alkenyl quaternized cellulose: B1. Add cellulose to a 20wt% sodium hydroxide solution at a ratio of 10g:250mL, sonicate for 8min, stir at room temperature for 3h, and collect the pretreated cellulose after filtration.
[0053] B2. Add 10wt% sodium hydroxide solution and epichlorohydrin to the pretreated cellulose. The ratio of pretreated cellulose, sodium hydroxide solution and epichlorohydrin is 10g:250mL:250mL. Stir and react at 65℃ for 8h. After filtration, dry at 80℃ for 6h to obtain epoxidized cellulose.
[0054] B3. Prepare a dimethylallylamine isopropanol solution with a dimethylallylamine concentration of 40 wt%. Add the dimethylallylamine isopropanol solution to the epoxidized cellulose. The ratio of epoxidized cellulose to dimethylallylamine isopropanol solution is 10 g: 250 mL. Stir the reaction at 45 °C for 10 h. After filtration, wash the cellulose sequentially with anhydrous ethanol, deionized water, 0.1 M sodium hydroxide solution, and 0.1 M hydrochloric acid solution. Finally, rinse with deionized water and dry under vacuum at 60 °C for 4 h to obtain alkenyl quaternized cellulose.
[0055] Example
[0056] Example 1
[0057] Preparation of TAC composite membrane
[0058] Step 1: Prepare the raw materials for the cellulose triacetate solution according to the following mass proportions: 20 parts cellulose triacetate, 1.5 parts thiolated cellulose prepared in Preparation Example 1, 0.2 parts triphenyl phosphate plasticizer, 0.3 parts UV326 ultraviolet absorber, and 90 parts mixed solvent (dichloromethane and methanol in a mass ratio of 92:8). Add the cellulose triacetate, the thiolated cellulose prepared in Preparation Example 1, the triphenyl phosphate plasticizer, and the UV326 ultraviolet absorber to the mixed solvent and stir until homogeneous to obtain the cellulose triacetate solution. After degassing, cast the solution to obtain a modified TAC base film with a thickness of 50 μm.
[0059] Step 2: Prepare the raw materials for the coating slurry according to the following mass proportions: 30 parts polyurethane acrylate, 6 parts alkenyl quaternized cellulose prepared in Preparation Example 4, 1.0 part 1-hydroxycyclohexylphenyl ketone photoinitiator, and 45 parts solvent (ethanol and ethyl acetate in a volume ratio of 1:1). Add the polyurethane acrylate, alkenyl quaternized cellulose prepared in Preparation Example 4, and 1-hydroxycyclohexylphenyl ketone photoinitiator to the solvent and stir evenly to obtain the coating slurry. Coat the coating slurry onto the surface of the modified TAC base film, dry at 90°C for 10 min, irradiate under 100 mW / cm ultraviolet light for 10 min, and after UV curing, form a functional protective coating with a coating thickness of 5 μm to obtain the TAC composite film.
[0060] Example 2
[0061] The only difference from Example 1 is that the thiolated esterified cellulose prepared in Example 2 is used instead of the thiolated esterified cellulose prepared in Example 1, while the other steps and conditions are the same as in Example 1.
[0062] Example 3
[0063] The only difference from Example 1 is that the thiolated esterified cellulose prepared in Example 3 is used instead of the thiolated esterified cellulose prepared in Example 1, while the other steps and conditions are the same as in Example 1.
[0064] Example 4
[0065] The only difference from Example 1 is that the alkenyl quaternized cellulose prepared in Example 5 is used instead of the alkenyl quaternized cellulose prepared in Example 4, while the other steps and conditions are the same as in Example 1.
[0066] Example 5
[0067] The only difference from Example 1 is that the alkenyl quaternized cellulose prepared in Example 6 is used instead of the alkenyl quaternized cellulose prepared in Example 4, while the other steps and conditions are the same as in Example 1.
[0068] Example 6
[0069] The only difference from Example 1 is that the mass fraction of the thiol-esterified cellulose prepared in Example 1 is adjusted to 1 part, while the other steps and conditions are the same as in Example 1.
[0070] Example 7
[0071] The only difference from Example 1 is that the mass fraction of thiolated esterified cellulose prepared in Example 1 is adjusted to 2 parts, while the other steps and conditions are the same as in Example 1.
[0072] Example 8
[0073] The only difference from Example 1 is that the mass fraction of the alkenyl quaternized cellulose prepared in Example 4 was adjusted to 4 parts, while the other steps and conditions were the same as in Example 1.
[0074] Example 9
[0075] The only difference from Example 1 is that the mass fraction of the alkenyl quaternized cellulose prepared in Example 4 was adjusted to 8 parts, while the other steps and conditions were the same as in Example 1.
[0076] Examples 10-11
[0077] The only difference from Example 1 is the amount of additives used in the TAC composite membrane, as shown in Table 1.
[0078] Table 1
[0079] Comparative Example 1
[0080] The only difference from Example 1 is that no mercapto-esterified cellulose is added to the cellulose triacetate solution.
[0081] Preparation of TAC composite membrane
[0082] Step 1: Prepare the raw materials for the cellulose triacetate solution according to the following mass proportions: 20 parts cellulose triacetate, 0.2 parts triphenyl phosphate plasticizer, 0.3 parts UV326 ultraviolet absorber, and 90 parts mixed solvent (dichloromethane and methanol in a mass ratio of 92:8). Add the cellulose triacetate, triphenyl phosphate plasticizer, and UV326 ultraviolet absorber to the mixed solvent and stir evenly to obtain the cellulose triacetate solution. After degassing, cast the solution to obtain a modified TAC base film with a thickness of 50 μm.
[0083] Step 2: Prepare the raw materials for the coating slurry according to the following mass proportions: 30 parts polyurethane acrylate, 6 parts alkenyl quaternized cellulose prepared in Preparation Example 4, 1.0 part 1-hydroxycyclohexylphenyl ketone photoinitiator, and 45 parts solvent (ethanol and ethyl acetate in a volume ratio of 1:1). Add the polyurethane acrylate, alkenyl quaternized cellulose prepared in Preparation Example 4, and 1-hydroxycyclohexylphenyl ketone photoinitiator to the solvent and stir evenly to obtain the coating slurry. Coat the coating slurry onto the surface of the modified TAC base film, dry at 90°C for 10 min, irradiate under 100 mW / cm ultraviolet light for 10 min, and after UV curing, form a functional protective coating with a coating thickness of 5 μm to obtain the TAC composite film.
[0084] Comparative Example 2
[0085] The only difference from Example 1 is that the alkenyl quaternized cellulose is replaced with an equal mass of quaternized cellulose in the coating slurry.
[0086] Preparation of quaternized cellulose: B1. Add cellulose to a 20wt% sodium hydroxide solution at a ratio of 10g:250mL, sonicate for 8min, stir at room temperature for 3h, and collect the pretreated cellulose after filtration.
[0087] B2. Add 10wt% sodium hydroxide solution and epichlorohydrin to the pretreated cellulose. The ratio of pretreated cellulose, sodium hydroxide solution and epichlorohydrin is 10g:250mL:250mL. Stir and react at 65℃ for 8h. After filtration, dry at 80℃ for 6h to obtain epoxidized cellulose.
[0088] B3. Prepare a dodecylamine isopropanol solution with a dodecylamine concentration of 35 wt%. Add the dodecylamine isopropanol solution to the epoxidized cellulose. The ratio of epoxidized cellulose to dodecylamine isopropanol solution is 15 g: 250 mL. Stir the reaction at 45 °C for 10 h. After filtration, wash with anhydrous ethanol, deionized water, 0.1 M sodium hydroxide solution and 0.1 M hydrochloric acid solution in sequence. Finally, rinse with deionized water and dry under vacuum at 60 °C for 4 h to obtain quaternized cellulose.
[0089] Preparation of TAC composite membrane
[0090] Step 1: Prepare the raw materials for the cellulose triacetate solution according to the following mass proportions: 20 parts cellulose triacetate, 1.5 parts thiolated cellulose prepared in Preparation Example 1, 0.2 parts triphenyl phosphate plasticizer, 0.3 parts UV326 ultraviolet absorber, and 90 parts mixed solvent (dichloromethane and methanol in a mass ratio of 92:8). Add the cellulose triacetate, the thiolated cellulose prepared in Preparation Example 1, the triphenyl phosphate plasticizer, and the UV326 ultraviolet absorber to the mixed solvent and stir until homogeneous to obtain the cellulose triacetate solution. After degassing, cast the solution to obtain a modified TAC base film with a thickness of 50 μm.
[0091] Step 2: Prepare the raw materials for the coating slurry according to the following mass proportions: 30 parts polyurethane acrylate, 6 parts quaternized cellulose, 1.0 part 1-hydroxycyclohexylphenyl ketone photoinitiator, and 45 parts solvent (ethanol and ethyl acetate in a volume ratio of 1:1). Add the polyurethane acrylate, quaternized cellulose, and 1-hydroxycyclohexylphenyl ketone photoinitiator to the solvent and stir evenly to obtain the coating slurry. Apply the coating slurry to the surface of the modified TAC base film, dry at 90℃ for 10 min, irradiate under 100mW / cm ultraviolet light for 10 min, and after UV curing, form a functional protective coating with a coating thickness of 5μm, thus obtaining the TAC composite film.
[0092] Comparative Example 3
[0093] The only difference from Example 1 is that polyurethane acrylate is used to replace alkenyl quaternized cellulose in the coating slurry.
[0094] Preparation of TAC composite membrane
[0095] Step 1: Prepare the raw materials for the cellulose triacetate solution according to the following mass proportions: 20 parts cellulose triacetate, 1.5 parts thiolated cellulose prepared in Preparation Example 1, 0.2 parts triphenyl phosphate plasticizer, 0.3 parts UV326 ultraviolet absorber, and 90 parts mixed solvent (dichloromethane and methanol in a mass ratio of 92:8). Add the cellulose triacetate, the thiolated cellulose prepared in Preparation Example 1, the triphenyl phosphate plasticizer, and the UV326 ultraviolet absorber to the mixed solvent and stir until homogeneous to obtain the cellulose triacetate solution. After degassing, cast the solution to obtain a modified TAC base film with a thickness of 50 μm.
[0096] Step 2: Prepare the raw materials for the coating slurry according to the following mass proportions: 36 parts polyurethane acrylate, 1.0 part 1-hydroxycyclohexylphenyl ketone photoinitiator, and 45 parts solvent (ethanol and ethyl acetate in a volume ratio of 1:1). Add the polyurethane acrylate and 1-hydroxycyclohexylphenyl ketone photoinitiator to the solvent and stir evenly to obtain the coating slurry. Apply the coating slurry to the surface of the modified TAC base film, dry at 90℃ for 10 min, irradiate under 100mW / cm ultraviolet light for 10 min, and after UV curing, a functional protective coating is formed with a coating thickness of 5μm, thus obtaining the TAC composite film.
[0097] The performance of the TAC composite membranes prepared in Examples 1-11 and Comparative Examples 1-3 was tested, and the results are shown in Table 2.
[0098] The transmittance was measured in accordance with the standard GB / T 25273-2025 Determination of Haze and Transmittance of Thin Films for Liquid Crystal Displays (LCDs) - Integrating Sphere Method.
[0099] Peel strength test: The peel strength between the base film and the coating was tested using a Mark-10 device.
[0100] The water vapor transmission rate of the composite membrane was determined using a water vapor transmission rate tester. After the TAC composite membrane was placed at 60℃ and 80%RH for 48 hours, the surface resistance value of the composite membrane was determined using a surface resistance tester.
[0101] Table 2
[0102] As can be seen from Table 2, after optimizing the formulation with thiol-esterified cellulose and alkenyl quaternized cellulose, the coating of the TAC composite film prepared in the embodiments of the present invention has strong adhesion to the base film, tight interlayer structure, and excellent optical and antistatic properties.
[0103] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0104] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A TAC composite membrane, characterized in that, Including modified TAC base film and functional protective coating; The modified TAC-based film was prepared by casting a cellulose triacetate solution. The cellulose triacetate solution comprises the following raw materials by mass parts: 20 parts cellulose triacetate, 1-2 parts thiolated cellulose, 0.1-0.3 parts plasticizer, 0.1-0.4 parts UV absorber, and 80-100 parts mixed solvent; The functional protective coating is obtained by applying a coating slurry and then photocuring it. The coating slurry, by weight parts Including the following raw materials: The composition consists of 30 parts of light-curable acrylate prepolymer, 4-8 parts of alkenyl quaternized cellulose, 0.5-1.5 parts of photoinitiator, and 40-50 parts of solvent.
2. The TAC composite membrane according to claim 1, characterized in that, The thickness of the modified TAC base film is 40-60 μm; the thickness of the functional protective coating is 4-6 μm.
3. The TAC composite membrane according to claim 1, characterized in that, The preparation steps of the thiolated esterified cellulose are as follows: A1. Cellulose introduces carboxyl groups through an oxidation reaction to form oxidized cellulose. A toluene-water mixed solvent is prepared, and oxidized cellulose and ethylenedimerol are added to the mixed solvent. A2. Add concentrated sulfuric acid dropwise. After the addition is complete, heat to 80-90℃, stir for 6-8 hours, cool to room temperature, filter, wash and dry to obtain mercapto-esterified cellulose.
4. The TAC composite membrane according to claim 3, characterized in that, The oxidized cellulose was prepared by TEMPO oxidation; the carboxyl content of the oxidized cellulose was 1.0-2.0 mmol / g. The mass ratio of toluene to water in the toluene-water mixed solvent is 3-5:1; The mass ratio of oxidized cellulose to ethylenedimerol is 1:0.3-0.8; the ratio of oxidized cellulose to mixed solvent is (3g-4g):100mL.
5. The TAC composite membrane according to claim 1, characterized in that, The mixed solvent is a mixture of dichloromethane and methanol, with a mass ratio of dichloromethane to methanol of (90-92):(8-10).
6. The TAC composite membrane according to claim 1, characterized in that, The photocurable acrylate prepolymer is at least one of polyurethane acrylate, polyester acrylate, and epoxy acrylate.
7. The TAC composite membrane according to claim 1, characterized in that, The preparation steps of the alkenyl quaternized cellulose are as follows: B1. Add cellulose to a 10-20 wt% sodium hydroxide solution, sonicate for 5-10 min, stir at room temperature for 3-4 h, and collect the pretreated cellulose after filtration. B2. Add 10-20wt% sodium hydroxide solution and epichlorohydrin to the pretreated cellulose, stir and react at 60-70℃ for 6-8h, filter and dry to obtain epoxidized cellulose; B3. Add dimethylallylamine isopropanol solution to epoxidized cellulose, stir and react at 40-50℃ for 6-12h, filter, wash and vacuum dry to obtain alkenyl quaternized cellulose.
8. The TAC composite membrane according to claim 7, characterized in that, In step B1, the ratio of cellulose to sodium hydroxide solution is (10g-20g): 250mL.
9. A TAC composite membrane according to claim 7, characterized in that, In step B2, the ratio of the pretreated cellulose, sodium hydroxide solution, and epichlorohydrin is (10-20g): 250mL: 250mL; the concentration of dimethylallyl ammonium in the dimethylallyl ammonium isopropanol solution is 20-40wt%. The ratio of the epoxidized cellulose to the dimethylallyl ammonium isopropanol solution is (10-20) g: 250 mL.
10. A method for preparing a TAC composite membrane, characterized in that, The preparation of the TAC composite membrane according to any one of claims 1-9 includes the following steps: Step 1: Prepare the raw materials for the cellulose triacetate solution according to the proportion. Add cellulose triacetate, mercapto-esterified cellulose, plasticizer and UV absorber to the mixed solvent, stir evenly to obtain the cellulose triacetate solution, and after degassing, cast into a film to obtain the modified TAC base film. Step 2: Prepare the raw materials for the coating slurry according to the proportion. Add the photocurable acrylate prepolymer, alkenyl quaternized cellulose and photoinitiator to the solvent and stir evenly to obtain the coating slurry. Apply the coating slurry to the surface of the modified TAC base film, heat and dry and UV cure to form a functional protective coating, and obtain the TAC composite film.