High-hardness surface coating for polaroid and preparation method

Abstract

The invention discloses a high-hardness surface coating for a polaroid and a preparation method, and belongs to the field of polaroids for vehicle-mounted display. Comprising the following steps: 1) adding an additive into cellulose organic acid ester, stirring for reaction, and then introducing tetraethyl orthosilicate for reaction; 2) adding methacrylate, methyl ethyl ketone, propylene glycol monomethyl ether, an organic binder and metal ions into the mixture obtained in the step 1) to form a coating liquid; and (3) coating a polaroid film with the coating liquid obtained in the step (2), and carrying out photopolymerization reaction to form the high-hardness surface coating for the polaroid. According to the method, a specific additive is introduced into the coating liquid, and a film is formed on the surface through photopolymerization-initiated crosslinking, so that the binding force of a coating and a base film is enhanced, the physical and chemical properties are improved, and finally, the surface coating of the high-hardness polaroid for vehicle-mounted display is realized.

Description

Technical Field

[0001] The present invention relates to the field of polaroids for vehicle-mounted displays, and in particular to a high-hardness surface coating for polaroids and a preparation method thereof. Background Art

[0002] With the rapid advancement of automotive intelligence and digital technology, in-vehicle displays have become an indispensable and key component of modern cars. In-vehicle displays are widely used in various functions such as in-vehicle entertainment systems, navigation, and driver assistance, and play a vital role in improving the driving experience and safety. In order to ensure the long-term stability and excellent visual effects of in-vehicle displays, the hardness and scratch resistance of polarizers have become one of the key issues in design and manufacturing. The in-vehicle display environment is complex and changeable, often facing challenges such as strong sunlight, drastic temperature fluctuations, moisture, and frequent physical friction. As the core optical component of liquid crystal displays (LCDs) or organic light-emitting diodes (OLEDs), polarizers must have high hardness and excellent scratch resistance to ensure that they can maintain a good display effect for a long time.

[0003] The advantage of high-hardness polarizers is that they effectively prevent scratches and abrasions caused by external physical impacts such as fingerprints, dust, and keys, thereby protecting the display surface coating and maintaining low reflectivity and clarity. Furthermore, high-hardness polarizers effectively extend their service life, reducing the cost and inconvenience of frequent replacements. Especially in automotive environments, where polarizers must withstand frequent touch operations and the harsh test of the external environment, high-hardness coatings can effectively reduce scratch damage, thereby ensuring the long-term stability and high performance of in-vehicle display systems.

[0004] To achieve the goal of manufacturing high-hardness polarizers, existing technologies face multiple challenges. For example, improving the hardness of the polarizer surface requires improving the molecular structure and formulation of the coating material to ensure high hardness and wear resistance while ensuring optical transparency.

[0005] Through technological innovation and process optimization, the present invention develops a high-hardness surface coating for polarizers that significantly improves the scratch resistance of vehicle-mounted display screens, extends their service life, and provides drivers with a clearer, more stable and safer visual experience, pushing vehicle-mounted display technology into a new stage. Summary of the Invention

[0006] The purpose of the present invention is to solve the above-mentioned problem in the prior art that the existing polarizer for vehicle display is easily scratched when subjected to external physical friction, and to provide a high-hardness surface coating for polarizer and a preparation method.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a high-hardness surface coating for a polarizer comprises the following steps:

[0009] 1) Add additives to cellulose organic acid ester, stir to react, and then introduce tetraethyl orthosilicate to react;

[0010] 2) adding methacrylate, methyl ethyl ketone, propylene glycol monomethyl ether, an organic binder, and metal ions to the mixture obtained in step 1) to form a coating solution;

[0011] 3) The coating liquid of step 2) is coated on the polarizer film and subjected to photopolymerization reaction to form the high-hardness surface coating for the polarizer.

[0012] The cellulose organic acid ester includes at least one of cellulose acetate, cellulose nitrate, cellulose acetate, cellulose acetate butyrate, and cellulose xanthate.

[0013] The additive includes at least one of succinic acid, phthalate, phosphate, citrate, polyurethane, and silicone.

[0014] The organic binder includes at least one of polyacrylic acid and polyimide.

[0015] The metal ions include at least one of sodium ions, potassium ions, zinc ions, magnesium ions, and iron ions.

[0016] In the present invention, 0.1 to 50 parts of additives, 10 to 20 parts of tetraethyl orthosilicate, 0.1 to 3 parts of methacrylate, 0.1 to 5 parts of methyl ethyl ketone, 0.1 to 3 parts of propylene glycol monomethyl ether, 1 to 5 parts of organic binder, and 0.1 to 0.5 parts of metal ions are introduced into 100 parts of cellulose organic acid ester by mass.

[0017] A high-hardness surface coating for a polarizer is prepared by adopting the above preparation method.

[0018] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0019] 1. Optimize coating uniformity and physical properties and improve production stability: The present invention introduces additives and nanoparticles during the coating process, which not only optimizes the surface structure of the coating, but also improves the uniformity and stability of the coating, and improves the physical properties of the coating, such as hardness and scratch resistance.

[0020] 2. Enhanced coating weather resistance, aging resistance, and adhesion: By optimizing the coating liquid composition and introducing metal ions, this invention enhances the coating's weather resistance, aging resistance, and adhesion to the base film. Specifically, metal ions (such as sodium, potassium, and zinc) complex with the hydroxyl groups in the cellulose acetate molecular chain, increasing the coating's structural stability and effectively improving its resistance to wear, UV radiation, and environmental corrosion over long-term use. This ensures that the polarizer maintains better performance over time, extending its service life.

[0021] 3. Significantly Improved Hardness, Enhanced In-Vehicle Display Quality: The coating of this invention exhibits excellent adhesion, indicating that curing and crosslinking significantly strengthen the bond between the film and coating. Only small flakes have fallen off at the intersection of the cuts, and actual damage within the cross-cut area is less than 5%, resulting in a 4B grade, successfully achieving a high-hardness coating. This high-hardness coating, formed through a photopolymerization reaction triggered by ultraviolet light, can effectively reduce the damaging effects of external physical friction and enhance display quality. In particular, in in-vehicle display applications, it can reduce damage to the display screen caused by physical friction, provide clearer images, and thus enhance the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the thickness of the substrate for high hardness surface coating.

[0023] Figure 2 This is the SEM image of the high hardness surface coating.

[0024] Figure 3 Elemental composition analysis of high hardness surface coatings.

[0025] Figure 4 Use the pencil method to measure the surface hardness of high hardness surface coatings.

[0026] Figure 5 ASTM rating for high hardness surface coatings.

[0027] Figure 6 Steel wool scratch test for high hardness surface coatings.

[0028] Figure 7 For contact angle testing of high hardness surface coatings. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0030] The method for preparing the high-hardness surface coating for polarizers of the present invention comprises the following steps:

[0031] 1. Introduce 1 part of succinic acid as an additive to 100 parts of cellulose acetate (TAC) and stir the reaction for 10 minutes; then introduce 15 parts of tetraethyl orthosilicate and utilize its hydrolysis and condensation reaction with cellulose acetate (TAC) to form SiO2 microspheres in situ. Compared with the traditional sol-gel method, it effectively overcomes the problem of nanoparticle agglomeration. At the same time, further introduce 2 parts of methacrylate, 3 parts of methyl ethyl ketone, 1 part of propylene glycol monomethyl ether, 2 parts of polyimide organic binder and 0.2 parts of Zn 2+ Metal ions constitute the coating liquid.

[0032] 2. Apply the coating liquid on the PVA film and perform ultraviolet light-induced polymerization curing to form a high-hardness surface coating.

[0033] The prepared high hardness surface coating was characterized by SEM, and the base film thickness was 38~40μm ( Figure 1 ); Through SEM observation of the hard coating sample, it can be seen that the surface of the high hardness surface coating is relatively uniform and dense, and no large-scale nanoparticle agglomeration phenomenon is found ( Figure 2 Nanoaggregates can be seen in a small number of areas, and elemental scanning analysis shows that they contain Si elements ( Figure 3 ), indicating that the high hardness surface coating formed has successfully introduced silica microspheres. The present invention successfully introduced inorganic nano-silica particles into the high hardness surface coating through the TEOS hydrolysis condensation method. According to the national standard GB / T6739-2006, the surface concave and convex structure of the high hardness coating was clearly visible using the pencil method, and the test hardness was 3H ( Figure 4 Adhesion was tested according to ASTM D3359-09 standard method, and it was found that the high hardness coating had good adhesion, indicating that the curing and cross-linking greatly strengthened the bonding between the base film and the coating. Only small pieces fell off at the intersection of the cut, and the actual damage in the cross-cut area was less than 5%, which was judged to be 4B grade ( Figure 5 ). Scratch resistance test was carried out according to GB / T24116-2008. The results showed that high hardness coatings have good scratch resistance ( Figure 6 The contact angle test shows that the high hardness coating is relatively hydrophobic, with an average contact angle of about 77° ( Figure 7 ), which greatly improved the weather resistance of the polarizer. The above test results show that the coating obtained by the new coating liquid formula developed by this invention significantly enhanced the surface hardness of the cellulose acetate (TAC) protective layer, achieving high hardness.

[0034] The specific principles of this invention are as follows: additives are introduced into cellulose acetate (TAC) to enhance hydrogen bonding between TAC molecules, improve crystallinity, and form a cross-linked network with the TAC to form a coating layer. This addresses technical bottlenecks such as uneven coating, weathering resistance, and aging resistance, as well as weak bonding between the coating layer and the base film. Secondly, nanoparticles are introduced into the coating liquid to enhance the surface properties of the TAC protective layer. Photoinitiated polymerization is used to construct a high-hardness coating. Furthermore, a small amount of metal ions can be introduced into the coating liquid to further enhance the coating's weather resistance through complexation with the hydroxyl groups on the TAC molecular chains.

Claims

1. A method for preparing a high-hardness surface coating for a polarizer, characterized in that: The following steps are involved: 1) Add additives to cellulose organic acid ester, stir to react, and then introduce tetraethyl orthosilicate to react; 2) adding methacrylate, methyl ethyl ketone, propylene glycol monomethyl ether, an organic binder, and metal ions to the mixture obtained in step 1) to form a coating solution; 3) The coating liquid of step 2) is coated on the polarizer film and subjected to photopolymerization reaction to form the high-hardness surface coating for the polarizer.

2. The method for preparing a high-hardness surface coating for a polarizer according to claim 1, wherein: The cellulose organic acid ester includes at least one of cellulose acetate, cellulose nitrate, cellulose acetate, cellulose acetate butyrate, and cellulose xanthate.

3. The method for preparing a high-hardness surface coating for a polarizer according to claim 1, wherein: The additive includes at least one of succinic acid, phthalate, phosphate, citrate, polyurethane, and silicone.

4. The method for preparing a high-hardness surface coating for a polarizer according to claim 1, wherein: The organic binder includes at least one of polyacrylic acid and polyimide.

5. The method for preparing a high-hardness surface coating for a polarizer according to claim 1, wherein: The metal ions include at least one of sodium ions, potassium ions, zinc ions, magnesium ions, and iron ions.

6. The method for preparing a high-hardness surface coating for a polarizer according to claim 1, wherein: In parts by mass, 0.1-50 parts of additives, 10-20 parts of tetraethyl orthosilicate, 0.1-3 parts of methacrylate, 0.1-5 parts of methyl ethyl ketone, 0.1-3 parts of propylene glycol monomethyl ether, 1-5 parts of organic binder, and 0.1-0.5 parts of metal ions are introduced into 100 parts of cellulose organic acid ester.

7. A high-hardness surface coating for a polarizer, characterized in that: Prepared by the preparation method according to any one of claims 1 to 6.

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