TPU mobile phone case with improved silk printing precision and preparation method thereof

Abstract

The application relates to the field of mobile device accessories, and discloses a TPU mobile phone shell improving screen printing precision and a preparation method thereof, which is composed of the following components: 85-95% of modified TPU material, the tensile strength of the modified TPU material being greater than or equal to 20 MPa, and the elongation at break being greater than or equal to 500%; 3-8% of functional additives, including a surfactant and modified nanometer material, wherein the surfactant is a fluoroalkyl coupling agent, the nanometer material is amino-functionalized nanometer silicon dioxide, and the particle size of the nanometer material is less than 200 nm; 1-3% of pigments, the diameter of the pigment particles being less than 1 micron; and 2-3% of self-assembled coating material, the coating material being polytetrafluoroethylene or polydimethylsiloxane, and the thickness of the coating being controlled to be 0.05 mm. Through the combination of the modified TPU material and the functional additives, the effects of significantly improving screen printing precision and pattern stability are achieved.

Description

Technical Field

[0001] This invention relates to the field of mobile device accessories, specifically to a TPU mobile phone case for improving screen printing accuracy and its preparation method. Background Technology

[0002] With the increasing demand for personalized consumption, screen printing has become one of the main technologies for creating colorful patterns on customized phone cases. The demand for personalized phone cases has spurred innovation in printing technology, but due to the limitations of the phone case materials themselves, screen printing often encounters technical bottlenecks, especially when the printed design contains complex patterns. Traditional thermoplastic polyurethane (TPU) materials have high elasticity, making their surface tension unstable and causing the printed pattern to easily deform. Especially with the increasing complexity of pattern details and text, existing technologies cannot effectively guarantee the sharpness of pattern edges and color saturation. This results in phone cases that not only lack visual clarity but also affect the consistency and aesthetics of the product.

[0003] Existing TPU phone cases commonly suffer from blurred edges and insufficient color saturation during screen printing, especially when the design includes small text or complex lines. Conventional TPU materials, due to unstable surface tension, struggle to ensure uniform ink adhesion when exposed to printing ink, leading to ink diffusion or penetration and blurred patterns. Even with high-quality inks, current technology still struggles to overcome issues such as insufficient pattern precision and poor color saturation. This is particularly evident in details, where the clarity of text and the delicacy of lines often fail to meet users' high-precision demands for personalized designs.

[0004] Existing technologies typically employ pretreatment measures, such as applying a hard coating to the surface or adjusting the ink formulation. Applying a hard coating can increase ink adhesion to some extent; however, the thickness and hardness of the coating may negatively impact the feel of the phone case, diminishing the original elasticity and comfort of the TPU material. Secondly, an excessively thick coating may cause the phone case surface to lose its original softness and durability, even affecting its abrasion resistance, potentially leading to coating peeling and fading after prolonged use. Adjusting the ink formulation also has limitations. While formula optimization can improve printing results, it's difficult to simultaneously improve screen printing quality while maintaining the physical properties of the raw materials, such as elasticity and scratch resistance. During production, these measures not only increase process complexity but also raise production costs, making it difficult to meet the efficiency requirements of large-scale production. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a TPU phone case with improved screen printing accuracy and its preparation method. This solves the problem that existing preparation methods may result in a poor feel for the phone case due to the thickness and hardness of the coating, causing it to lose the original elasticity and comfort of the TPU material. An excessively thick coating may cause the phone case surface to lose its original softness and durability, and may even affect the wear resistance of the phone case. After long-term use, the coating may peel off or fade.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a TPU phone case for improving screen printing accuracy, comprising the following components:

[0008] The modified TPU material comprises 85%–95%. By introducing end-group isocyanates, the modified TPU material enhances its oleophilicity and surface energy. This modification effectively increases the material's compatibility with inks, resulting in more precise screen-printed patterns. The modified TPU material possesses excellent mechanical properties, with a tensile strength ≥20MPa and an elongation at break ≥500%. This makes the material not only durable but also maintains deformation stability under complex processing conditions, thereby improving the fundamental stability of screen-printing accuracy.

[0009] Terminal isocyanates introduce polar groups (such as hydroxyl or amine groups) by reacting with active hydrogen on the TPU molecular chain, thereby increasing the surface energy of the material. This increased surface energy allows for better wetting of the ink upon contact with the material, reducing ink slippage or uneven distribution. Furthermore, intermolecular forces (such as hydrogen bonds or van der Waals forces) are generated between the polar groups and bonded molecules in the ink, further enhancing ink adhesion. The high mechanical properties of modified TPU provide a stable structural foundation for screen printing, avoiding the impact of material deformation on the pattern under complex conditions.

[0010] The functional additives consist of 3% to 8% surfactants and nano-modifiers.

[0011] The surfactant used is a fluoroalkyl coupling agent, which enhances the surface polarity of the TPU material by forming a thin layer on the surface. This effect improves ink adhesion, resulting in clearer screen printing results.

[0012] Fluoroalkyl coupling agents possess a unique amphiphilic structure. Their hydrophobic segments bind to TPU materials, while their hydrophilic end groups align on the material surface, forming a regular molecular layer. This molecular layer not only increases the surface energy of the material but also enables physical adsorption and chemical bonding between the ink and surface molecules, significantly enhancing ink adhesion. Simultaneously, the regular arrangement of the molecular layer reduces surface roughness, contributing to improved clarity and uniformity of screen-printed patterns.

[0013] The nano-modifier is amino-functionalized nano-silica with a particle size of 50nm to 150nm, which can further improve the microstructure and surface properties of the material.

[0014] Amino-functionalized nano-silica, with its small particle size (50nm–150nm) uniformly distributed on the TPU surface, fills microscopic pores, thereby smoothing the surface structure. Furthermore, the amino groups chemically bond with polar molecules in the ink, further enhancing adhesion. The filling effect of the nanoparticles also optimizes surface tension distribution, preventing uneven diffusion during screen printing and improving pattern accuracy.

[0015] Pigment (1%–3%).

[0016] Using pigments with a particle size of less than 1μm ensures uniform dispersion of the pigment in the material. The small particle size prevents particle aggregation and the formation of a rough surface, while not affecting the smoothness and fineness of the printed pattern.

[0017] Smaller pigment particles significantly reduce light scattering on the material surface, resulting in sharper and clearer screen-printed patterns. Furthermore, the small particle size ensures uniform pigment distribution within the TPU substrate, preventing particle accumulation from causing irregularities on the screen-printed surface. Simultaneously, the uniformly dispersed pigment forms a high-opaque coating layer, which not only enhances color saturation but also improves edge sharpness and detail.

[0018] 2%–3% of self-assembling coating materials.

[0019] The coating material is selected from polytetrafluoroethylene or polydimethylsiloxane, and its coating thickness is controlled between 0.02mm and 0.05mm. This coating material forms a uniform film on the TPU surface through an impregnation method, enhancing the wear resistance and screen printing stability of the material surface.

[0020] The fluorine or silicon groups in the molecules of coating materials (such as PTFE or PDMS) have extremely low surface energy. This property significantly reduces the surface tension when ink adheres, making it easier for the ink to spread evenly on the coating surface. This reduces interference factors in the screen-printed pattern and improves the screen-printing accuracy.

[0021] The coating molecules have self-assembly capabilities, forming a thin layer with a regular arrangement on the material surface. This arrangement not only further reduces the surface roughness of the coating but also significantly enhances its mechanical stability and wear resistance, making the screen-printed pattern more durable.

[0022] The coating is applied uniformly using an immersion method, with its thickness strictly controlled within the range of 0.02mm to 0.05mm. This thickness ensures the protective properties of the coating while avoiding the negative impacts that excessive coating thickness might have on the tactile feel and ink diffusion.

[0023] This invention also provides a method for preparing a TPU mobile phone case to improve screen printing accuracy, specifically including the following steps:

[0024] Step 1: Mixing the ingredients:

[0025] Modified TPU, functional additives, and pigments are mixed in proportions by weight, ensuring a mixing uniformity of ≥95%.

[0026] Uniform mixing ensures the even distribution of modifiers and pigments in the material, thereby guaranteeing improved surface energy and full utilization of the pigments' optical properties. In particular, the uniform distribution of additives avoids localized excessively high or low polarity, reducing screen printing defects.

[0027] Step 2: High-temperature extrusion molding:

[0028] The mixed materials are extruded at a high temperature of 180℃~220℃ to form the TPU mobile phone case body.

[0029] High-temperature extrusion, on the one hand, melts and flows the material, promoting a more uniform distribution of different components; on the other hand, by controlling the temperature range, it ensures that the modification effect and mechanical properties of the material are not compromised. Furthermore, the shearing action during extrusion helps the molecules of the additives to align on the material surface, laying the foundation for subsequent screen printing effects.

[0030] Step 3: Apply a self-assembling coating:

[0031] After extrusion molding, the TPU phone case is coated with a self-assembly coating material by dip coating, with the coating thickness controlled between 0.02mm and 0.05mm.

[0032] The impregnation method allows the coating material to be evenly distributed on the TPU surface through capillary action, forming a uniform film. The self-assembly properties of the coating (such as the automatic alignment of fluorine groups in the PTFE molecular chain) ensure its functionality. The coating not only provides abrasion resistance and surface smoothness but also further enhances the adhesion of screen printing inks by adjusting surface energy.

[0033] Step 3: Cooling and curing:

[0034] The coated TPU phone case is cooled and cured at 30℃~40℃ for 30~45 minutes.

[0035] Temperature control during the cooling process ensures the orderly arrangement and cross-linking curing of the coating material's molecular chains, avoiding coating defects caused by rapid cooling. Furthermore, slow cooling allows for full bonding between the nanoparticles and the coating, improving the material's surface properties.

[0036] This invention provides a method for manufacturing TPU mobile phone cases that improves screen printing accuracy. It has the following beneficial effects:

[0037] 1. This invention significantly improves screen printing accuracy and pattern stability by combining modified TPU materials with functional additives. Compared to existing technologies using ordinary TPU and traditional coatings, which often result in blurred pattern details, especially when printing small text and complex lines, this invention enhances ink adhesion and pattern clarity by adjusting the surface oleophilicity of TPU and using nano-silica and fluoroalkyl coupling agents, thus solving the problems of pattern distortion and insufficient precision in existing solutions.

[0038] 2. This invention modifies TPU material with end-group isocyanates, maintaining its original resilience and scratch resistance while improving screen printing quality. Unlike existing technologies that sacrifice material physical properties to improve pattern quality, this invention avoids this compromise. The modified TPU not only improves the screen printing effect but also enhances the durability and feel of the phone case, making it more advantageous in long-term use.

[0039] 3. This invention optimizes the production process by employing high-temperature extrusion molding and micro-coating, simplifying the traditional complex surface treatment process and achieving the technical effects of improving production efficiency and reducing costs. Compared with the complex processes in existing technologies that require multiple pretreatment and surface spraying steps, this invention eliminates the cumbersome spraying and coating hardening steps, reducing material waste and production time, greatly improving production efficiency, and lowering overall manufacturing costs.

[0040] 4. This invention significantly improves the wear resistance and durability of the pattern through a self-assembling coating of polytetrafluoroethylene (PTFE) or polydimethylsiloxane (PDMS). Compared to the problems of fading and peeling caused by excessively thick coatings in existing technologies, this invention avoids these problems through a thin coating design, while enhancing the stability of the pattern and ensuring that the pattern on the phone case remains vibrant and clear even after prolonged use, avoiding premature wear and fading. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Please see the appendix Figure 1 This invention provides a method for preparing a TPU mobile phone case with improved screen printing accuracy, comprising the following steps:

[0044] S1. The modified TPU material, functional additives, and pigments are mixed according to the following mass proportions:

[0045] Modified TPU material 85%–95%;

[0046] Functional additives: 3%–8%;

[0047] Pigment 1%–3%.

[0048] S2. The mixed material is extruded at a high temperature of 180℃~220℃ to obtain the main body of the TPU mobile phone case.

[0049] S3. A self-assembly coating material is coated on the surface of the TPU phone case, the coating thickness is controlled between 0.02mm and 0.05mm, and the coating is applied by immersion method.

[0050] S4. Cool and cure the TPU phone case coated with the self-assembly coating. The cooling temperature is controlled at 30℃~50℃ and the curing time is 30~60 minutes.

[0051] Example 1:

[0052] Step 1: Mixing raw materials

[0053] Take 85% modified TPU, 5% functional additives (including fluoroalkyl coupling agents and amino-functionalized nano silica), 2% pigments (particle diameter less than 1μm), and 8% other components (such as surfactants or other auxiliary components), mix them evenly in proportion to ensure uniform distribution of additives and pigments.

[0054] Step 2: High-temperature extrusion molding

[0055] The mixed raw materials are placed into an extruder, and the extrusion temperature is set at 190℃ to ensure that the material is completely melted and to avoid overheating that could cause the components to decompose. After extrusion molding, a TPU phone case body of the predetermined shape is obtained.

[0056] Step 3: Cooling and curing

[0057] The molded phone case is allowed to cool naturally at a temperature of 30°C for 30 minutes to ensure structural stability.

[0058] Step 4: Coating the surface micro-layer

[0059] The polytetrafluoroethylene (PTFE) coating material was dissolved in an appropriate amount of solvent and applied to the surface of the TPU phone case using an immersion method, maintaining a coating thickness of 0.03 mm. After coating, it was dried at room temperature for 30 minutes.

[0060] Example 2:

[0061] Step 1: Raw material preparation

[0062] Mix all raw materials thoroughly according to the following ratio: 90% modified TPU, 3% functional additives (using silane coupling agents and hydrophobic nano-silica), 2% pigments, and 5% other components (such as surfactants or other auxiliary components) to ensure full fusion between the materials.

[0063] Step 2: High-temperature extrusion molding

[0064] The mixed raw materials are fed into the extruder, and the extrusion temperature is set to 210℃ to ensure that the modified TPU material can melt smoothly and to avoid excessive temperature from causing a decline in ink quality. During the molding process, ensure uniform mixing to obtain a qualified TPU shell.

[0065] Step 3: Surface Micro-layer Treatment

[0066] A 0.05mm thick polyamide coating is uniformly applied to the surface of the TPU shell. After drying, the coating surface is smooth, ensuring better adhesion of screen printing ink and significantly improving the screen printing effect.

[0067] Step 4: Cooling and Curing

[0068] After coating is completed, place the product in a cooling device, set the cooling temperature to 40℃, and control the curing time to 45 minutes to ensure that the coating is tightly bonded to the TPU substrate and has high stability.

[0069] Example 3:

[0070] Step 1: Ingredients and Mixing

[0071] The formula uses 85% modified TPU, 5% functional additives (including fluoroalkyl coupling agents and amino-functionalized nano-silica), 3% pigments (particle diameter less than 0.8 μm), and 2% other ingredients (such as surfactants or other auxiliary ingredients). All materials are thoroughly mixed to ensure that each component works effectively for optimal results.

[0072] Step Two: Molding and Extrusion

[0073] The premixed material is fed into an extruder, and the extrusion temperature is set at 200℃. After the material flows evenly, it is formed into the main body of the mobile phone case through a mold, ensuring that the surface of the case is smooth and the shape is accurate.

[0074] Step 3: Formation of surface coating and microlayer

[0075] Polydimethylsiloxane (PDMS) was used as the coating material, and the coating thickness was controlled at 0.02 mm. After the coating was applied, a low-temperature curing process was performed to ensure that the coating was uniform and stable, thereby increasing ink adhesion and pattern stability.

[0076] Step 4: Cooling and Curing

[0077] The phone case coated with the micro-layer was cooled at 35°C for 40 minutes to ensure that the physical properties of the phone case were not affected and to improve the durability of the pattern.

[0078] Comparative Example 1: Traditional TPU

[0079] Comparison content:

[0080] Modified TPU: The modified TPU material is replaced with traditional TPU, and the rest (functional additives, pigments, coatings, preparation process) is the same as in Example 1.

[0081] Functional additives: Mix the raw materials evenly according to the proportions in Example 1 to ensure consistent distribution of pigments and additives and avoid localized unevenness.

[0082] Difference analysis: Due to the lack of modified TPU, traditional TPU materials have low surface energy and cannot fully interact with additives and ink molecules, even if the raw materials and additives are evenly distributed.

[0083] Preparation process:

[0084] Using unmodified traditional TPU as the base material, a mixture was prepared at a ratio of 85% traditional TPU, 5% functional additives (including fluoroalkyl coupling agents and amino-functionalized nano-silica), 2% pigment (particle size approximately 1 μm), and 8% other auxiliary components. After ensuring uniform component distribution, the mixture was extruded at 190°C to form the initial body of the phone case. The phone case body was then allowed to cool naturally at 30°C for 30 minutes to ensure material shape stability. A hard coating (such as a polyurethane coating) was then sprayed onto the cooled phone case surface, with a coating thickness controlled at 0.03 mm. The coating was then dried at room temperature and cured for 30 minutes to obtain the final product.

[0085] Comparative Example 2: Uncoated Treatment

[0086] Comparison content:

[0087] Coating: No additional coating treatment is required; the screen printing process is carried out directly. All other aspects (functional additives, pigments, preparation process) are the same as in Example 2.

[0088] Preparation process:

[0089] Modified TPU (90%) was used as the base material, with 3% functional additives (including silane coupling agents and hydrophobic nano-silica), 2% pigments (particle size less than 1 μm), and 5% other auxiliary components (such as surfactants) added. After all raw materials were mixed evenly, the mixture was formed by high-temperature extrusion (extrusion temperature 210℃) to obtain the TPU mobile phone case body. The formed mobile phone case was cooled at 40℃ for 45 minutes to ensure structural stability. Unlike Example 2, this comparative example did not undergo any surface coating treatment, and the cooled mobile phone case was directly used for screen printing. Due to the lack of coating protection and optimization, the surface performance was poor, and the ink adhesion and screen printing accuracy were significantly lower than those of Example 2.

[0090] Comparative Example 3: Excessive Coating

[0091] Comparison content:

[0092] Coating: Using excessive coating (approximately 0.1 mm thick) may reduce pattern clarity and affect the feel. The remaining contents (functional additives, pigments, preparation process) are the same as in Example 3.

[0093] Preparation process:

[0094] Modified TPU (85%) was used as the base material, with 5% functional additives (including fluoroalkyl coupling agents and amino-functionalized nano-silica), 3% pigments (particle size less than 0.8μm), and 2% other auxiliary components (such as surfactants or other additives). All raw materials were mixed evenly and then fed into an extruder for molding. The extrusion temperature was set to 200℃ to ensure the raw materials were fully melted and evenly distributed. After molding, a 0.02mm thick polydimethylsiloxane (PDMS) coating was applied to the surface of the phone case. After coating, the phone case was cooled and cured at 35℃ for 40 minutes. Due to the excessive coating thickness, direct screen printing easily led to ink diffusion, resulting in poor pattern clarity and adhesion, a hard feel, and reduced overall product durability.

[0095] Experiment 1: Screen Printing Accuracy Test

[0096] Experimental steps:

[0097] Step 1: Prepare the sample

[0098] TPU phone case samples were selected from Example 1 and Comparative Example 1 to ensure that each group of samples was basically consistent in shape and surface treatment.

[0099] Step Two: Silk Screen Printing Design

[0100] Complex designs, including fine text and intricate lines, were selected to test the accuracy of the screen printing. The designs contained fine lines and text with a width of 0.2mm.

[0101] Step 3: Screen Printing Operation

[0102] Using an automated screen printing machine, uniform screen printing parameters were set: pressure of 10N, printing speed of 1.5m / s, ink temperature of 25℃, and humidity maintained at 50%. Each sample was printed three times to ensure the reliability of the results.

[0103] Step 4: Check the silkscreen effect

[0104] After screen printing is completed, the pattern of each sample is photographed using a high-resolution microscope. The edge sharpness, detail reproduction, and color saturation of the pattern are recorded, with particular attention paid to the rendering of fine lines and small text.

[0105] Step 5: Evaluation and Comparison

[0106] Image processing software is used to analyze the image, calculate the edge sharpness of the pattern (in pixels), and evaluate the detail reproduction. Finally, a comprehensive evaluation is conducted based on criteria such as the degree of pattern distortion, detail sharpness, and color consistency.

[0107] Experimental data:

[0108] Table 1: Comparison of Experimental Results for Screen Printing Accuracy

[0109]

[0110]

[0111] In summary, Example 1 demonstrates higher screen printing precision and pattern clarity. The fine lines and font clarity of Example 1 reached 98 pixels and 95 pixels respectively, significantly higher than the 85 pixels and 82 pixels of the comparison group. Simultaneously, the color saturation was also significantly better than the comparison group, highlighting the crucial role of the coating and functional additives in pattern reproduction. This effect is closely related to the mechanism of this invention; the improved surface oleophilicity and the introduction of functional additives effectively improved ink adhesion, allowing the ink to be evenly distributed and firmly adhered, thereby avoiding pattern distortion and blurring.

[0112] Furthermore, the self-assembly properties of the coating and the use of nanomaterials also play a crucial role in the clear reproduction of pattern details. By employing modified TPU and a special coating, this invention effectively enhances the surface microstructure of the TPU phone case, enabling it to better adapt to ink flow during the screen printing process and avoiding the ink diffusion problem commonly found in traditional methods. The detail is excellent; small text and fine lines are clearly visible in Example 1, maintaining high clarity and fullness.

[0113] Overall, this invention significantly improves pattern accuracy and screen printing effect compared to traditional TPU solutions, demonstrating its innovation and superiority. Due to the efficient formulation of functional additives and the optimization of the coating microstructure, pattern details are fully realized, and pattern distortion and blurring are virtually eliminated, bringing a breakthrough improvement to screen printing technology. This not only increases production efficiency but also enhances the visual and tactile experience for consumers using mobile phone cases.

[0114] Experiment 2: Ink Adhesion and Abrasion Resistance Test

[0115] Experimental steps:

[0116] Step 1: Prepare the sample:

[0117] Samples from Example 2 and Comparative Example 2 were selected to ensure that the shapes and surface treatments of the two groups of samples were consistent. Example 2 used modified TPU material, silane coupling agent, and nano-silica, with a coating thickness of 0.05 mm; the control group had no coating treatment, and the rest (functional additives, pigments, preparation process) were the same as in Example 2.

[0118] Step 2: Ink adhesion test:

[0119] Equipment: Coating adhesion tester (e.g., German) The test instrument was used to perform the test according to ISO 2409 standard. Steps:

[0120] The same screen printing was performed on the surfaces of both sets of samples, using the same batch of ink.

[0121] A scratch test was conducted using a standard hardness scribbler, with 20 scratches performed per test and a pressure of 10N per scratch.

[0122] Observe the ink peeling and record the percentage of the area where ink has peeled off.

[0123] Step 3: Abrasion resistance test:

[0124] Equipment: Taber abrasion testing machine, with abrasion testing performed according to ASTM D4060 standard. Procedure:

[0125] Ten samples each from Example 2 and the control group were placed in the wear tester.

[0126] The grinding wheel load was set to 500g, the rotation speed to 60 rpm, and the wear test was conducted 1000 times.

[0127] After testing, the surface damage was observed using a microscope, and the color difference and degree of surface damage after wear were recorded.

[0128] Experimental data:

[0129] Table 2: Ink Adhesion and Abrasion Resistance Test Results

[0130]

[0131] In summary, Example 2 demonstrates significant advantages in ink adhesion and abrasion resistance. Firstly, the ink adhesion test results show that the ink peeling area in Example 2 is significantly lower than that in the control group, indicating that the use of modified TPU, functional additives, and coatings enhances the adhesion between the ink and the surface. Compared to the control group sample without additional coating treatment, Example 2 exhibits more uniform and stable ink adhesion, which is closely related to the mechanism of the modified TPU and functional additives used in this invention. By enhancing the oleophilicity and stability of the material surface, the ink can adhere firmly, reducing ink peeling.

[0132] Furthermore, in the abrasion resistance test, Example 2 exhibited lower wear depth and color difference changes, indicating that the solution can maintain good pattern stability and surface quality during long-term use. Compared to the control group, Example 2 showed significantly less surface damage and less pattern fading after the abrasion test, reflecting the significant improvement in surface hardness and scratch resistance brought about by the self-assembled coating and nano-silica composite system used in this invention. The microstructure of the coating not only effectively protects the surface from scratch damage but also provides strong support for the durability of the pattern.

[0133] In summary, this experiment verifies the effectiveness of the present invention. It provides significant technical improvements in ink adhesion, abrasion resistance, and pattern durability without additional coating treatment. These results are closely related to the mechanism of the present invention; the combination of modified TPU material and functional additives not only enhances the surface's oleophilicity but also improves coating stability, enabling the ink to adhere more firmly to the surface and ensuring the pattern maintains high quality over long-term use.

[0134] Experiment 3: Abrasion Resistance and Pattern Durability Test

[0135] Experimental steps:

[0136] Step 1: Sample Preparation

[0137] Example 3 (modified TPU, fluoroalkyl coupling agent, nano silica, 0.02 mm coating) and Comparative Example 3 were selected with an excess coating (approximately 0.1 mm thick). The remaining contents (functional additives, pigments, preparation process) were the same as in Example 3 to ensure that the sample surface treatment was consistent and the dimensions were the same.

[0138] Step 2: Abrasion Resistance Test

[0139] Wear tests were performed using a Taber wear testing machine (compliant with ASTM D4060 standard).

[0140] The grinding head load is set to 500g and the grinding wheel speed is set to 60 revolutions per minute.

[0141] 1000 wear tests were conducted to simulate friction conditions during daily use.

[0142] During the test, the surface changes after wear were recorded, and the fading of the pattern, the degree of wear, and the surface damage were observed.

[0143] Step 3: Pattern Damage Assessment

[0144] After the test is completed, the sample surface is photographed using a microscope to observe the changes in the pattern, especially the wear of the pattern details.

[0145] Record the degree of fading, blurring of edges, and damage to the pattern.

[0146] Image analysis software was used to assess the preservation of pattern details and to record the pattern's sharpness and color difference.

[0147] Step 4: Comparative Analysis

[0148] The results of Example 3 and Comparative Example 3 were compared, particularly regarding pattern durability, surface damage from wear, and color difference, to analyze the differences in wear resistance between the two groups of samples.

[0149] Experimental data:

[0150] Table 3: Comparison Results of Abrasion Resistance and Pattern Durability Tests

[0151]

[0152] In summary, the experimental data show that Example 3 significantly outperforms the control group in terms of abrasion resistance and pattern durability. Example 3 exhibits lower pattern damage, color change, and loss of pattern detail, with a significantly lower wear depth compared to the control group. This difference stems from the combined use of modified TPU and functional additives in this invention, particularly the combination of fluoroalkyl coupling agents and nano-silica, which enhances the surface oleophilicity and abrasion resistance of the TPU. The modified TPU's molecular structure strengthens its scratch resistance, while nano-silica effectively improves the coating's surface structure, enhancing adhesion and stability, thereby improving pattern durability.

[0153] This experiment also verified the effect of coating thickness on abrasion resistance and pattern retention. The thin coating (0.02 mm) used in Example 3 effectively improved the retention of pattern details compared to the thick coating (0.1 mm) in the control group, while reducing the feel problems caused by excessive coating thickness. The uniformity of the coating and the micro-layer self-assembly structure improved the adhesion of the ink, preventing the pattern from fading or peeling off due to excessive friction.

[0154] This experiment demonstrates the significant effectiveness of the present invention's technical solution in improving the durability, pattern clarity, and longevity of mobile phone cases. Compared to traditional technologies, Embodiment 3 achieves innovative breakthroughs in several aspects. These advantages will give the present invention significant market competitiveness in terms of personalized customization, visual effects during long-term use, and user experience.

[0155] 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 TPU phone case for improving screen printing accuracy, characterized in that, The raw material composition includes the following parts by weight: Modified TPU material 85%–95%; Functional additives 3%–8%; Pigment 1%–3%; Self-assembly coating materials: 2%–3%; The modified TPU material is a thermoplastic polyurethane containing terminal isocyanates, and the modification improves the oleophilicity and surface energy of the TPU surface. The functional additives include surfactants and nano-modifiers, wherein the surfactant is a fluoroalkyl coupling agent; The nano-modifier is amino-functionalized nano-silica, and the nano-modifier accounts for 1% to 2% of the TPU mobile phone case raw material by weight. The coating material is polytetrafluoroethylene, polydimethylsiloxane or a blend thereof, and the mass percentage of the coating material is 2% to 3%.

2. The TPU phone case for improving screen printing accuracy according to claim 1, characterized in that, The particle size of the amino-functionalized nano-silica is 50 nm to 150 nm.

3. A method for manufacturing a TPU mobile phone case with improved screen printing accuracy, applied to the TPU mobile phone case with improved screen printing accuracy described in any one of claims 1-2, characterized in that, Includes the following steps: The modified TPU material, functional additives, and pigments are mixed according to the mass ratio; The mixed materials are extruded at a high temperature of 190℃~210℃ to obtain the main body of the TPU mobile phone case; A self-assembly coating material is applied to the surface of the TPU phone case; The TPU phone case coated with the self-assembly coating is cooled and cured, with the cooling temperature controlled between 30℃ and 50℃ and the curing time between 30 and 60 minutes.

4. The method for preparing a TPU mobile phone case with improved screen printing accuracy according to claim 3, characterized in that, The self-assembly coating is applied to the surface of the TPU phone case body after extrusion molding by dip-dip method, and the coating thickness is uniformly controlled between 0.02mm and 0.05mm.

5. The method for preparing a TPU mobile phone case with improved screen printing accuracy according to claim 3, characterized in that, The cooling temperature during the cooling and curing process is 30℃~40℃, and the curing time is 30~45 minutes.

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