Polyester fabrics have won widespread praise for their durability, wrinkle resistance, easy care, and quick drying. However, they also have a drawback. Poor hygroscopicity and limited color depth. These problems stem from the inherent properties of polyester fibers. Their smooth surface and lack of reactive groups. The significant difference in refractive index between polyester (nₛ = 1.73) and air (n₀ = 1.0) contributes to the high light reflection from the fiber surface. This results in insufficient color saturation. This makes it difficult to achieve deep, rich tones. Such as forest green, navy blue, deep purple, and deep black.
Traditional solutions involve post-processing with organofluorine or silicone resins. To form a uniform anti-reflective resin film on the surface of the fabric. Although these films successfully reduce reflections. But their hydrophobic nature further compromises the fabric’s ability to wick moisture. Additionally, the single refractive index of these resin antireflective films results in wavelength-selective performance. It limits their ability to accurately reproduce the original color of the fabric.
Therefore, there is a growing demand for new anti-reflective coatings. This coating provides long-lasting color enhancement without compromising the inherent qualities of the fabric. Different from traditional anti-reflective resin films. The use of porous antireflective coatings with adjustable refractive index has received significant attention in applications such as solar panels and optics. The sol-gel method used to produce these porous antireflective coatings offers advantages such as uniformity, cost-effectiveness, low processing temperatures, and simplified procedures. Aroused great interest. These coatings typically have a hydrophilic surface that is rich in hydroxyl groups. Ensures strong adhesion to sol-gel particles.
Our focus will be on innovative approaches to anti-reflective coatings using modified silica nanoparticles. Designed to improve color depth, moisture absorption, and color fastness of polyester fabrics. The method involves creating a stable porous cross-linked antireflective film with alkoxysilane groups on the surface of silica particles. The film is formed on polyester fabric through a simple soaking process. It is further enhanced during the baking stage. The alkoxysilane groups on the particle surface undergo a cross-linking reaction. A stable, porous, cross-linked anti-reflective network structure is formed on the surface of the fabric. This structure bonds well to the softened polyester fibers during the baking process. The presence of a large number of hydroxyl groups on the silica sol-gel surface also enhances the hydrophilic properties of the fabric.
The preparation of silica antireflective coating fluid is a multi-step process. Designed to create a stable and effective coating. To improve the color depth, moisture absorption, and color fastness of polyester fabrics. Let’s dive into the details of each step:
Mixing silica colloidal dispersion and silane coupling agent:
The process begins by mixing two key ingredients: a silica colloidal dispersion and a silane coupling agent. These materials are mixed in organic solvents. Silica colloidal dispersions contain tiny silica particles. Silane coupling agents act as surface modifiers. Contributes to the adhesion and reactivity of silica particles. The organic solvent acts as a medium for this mixture. Ensure components interact effectively with each other.
Adjust pH:
After initial mixing, the pH of the reaction mixture was adjusted to a range of 3 to 8. This pH change is a critical step that helps control reaction conditions. This ensures that the environment is conducive to the cross-linking and chemical reaction between the silica nanoparticles and the silane coupling agent. By adjusting the pH within this specific range. The desired properties of the resulting coating can be achieved.
Increase temperature:
Once the pH is adjusted appropriately. The temperature of the reaction mixture is increased to a range of 20°C to 50°C. Increasing temperature accelerates the chemical reaction between the silica nanoparticles and the silane coupling agent. These reactions are critical for modifying the surface of silica nanoparticles by attaching alkoxysilane surface groups. Higher temperatures speed up the formation of the required chemical bonds.
Allow the reaction to proceed:
With adjusted pH and increased temperature. The reaction is allowed to proceed for a duration of 12 to 40 hours. During this time, the chemical reaction between the silica nanoparticles and the silane coupling agent continues. This extended reaction time is necessary to ensure the formation of a stable, porous, cross-linked antireflective network structure on the surface of the silica nanoparticles.
The result of this complex process is an anti-reflective coating liquid. The liquid is mainly composed of silica nanoparticles. The surface of these nanoparticles is modified to contain alkoxysilane surface groups. These surface groups are critical for establishing strong adhesion between the silica nanoparticles and the polyester fabric during coating application. In addition, the porous nature of the coating helps achieve the anti-reflective and color-enhancing properties sought after in the final product.
The method represents a carefully controlled series of steps. Designed to create innovative anti-reflective coatings. Enhances the performance of polyester fabrics, providing better color depth, moisture absorption, and color fastness.
This new coating fluid offers several significant benefits. It is a game-changer in the field of textile reinforcement. Let’s explore these benefits in more detail:
The operation is simple and workable:
One of the outstanding features of this coating fluid is its ease of use. The preparation process is simple and practical. Importantly, it allows operation at lower temperatures. This is not only energy efficient but also more friendly. Additionally, avoiding the use of toxic solvents contributes to the safety and sustainability of the coating process. Complies with modern environmental standards and regulations.
High solid content:
The coating liquid has a high solid content. This means that a large part of the liquid consists of the active ingredients required for the coating. For example, modified silica nanoparticles. The benefit here is twofold. First, it reduces the need for excess storage space. Because less liquid is required to achieve the desired effect. Secondly, because there is less material to transport. Transportation costs are minimized. This can result in significant cost savings in large-scale applications.
No adhesive required:
During the coating process, no adhesive is required. This is a crucial advantage. Especially in the textile industry. Adhesives can change the texture of the fabric. It affects its feel and drape. By eliminating the need for adhesives. This coating process minimizes the negative impact on the original texture of the fabric. The resulting fabric retains its softness and comfort. These are very valuable properties in textiles.
Stable cross-linking reaction:
The cross-linking reactions between silica particles during the coating process play a key role in providing long-term stability. This cross-linking creates a strong, interconnected network structure on the surface of the fabric. So, the coating adheres firmly to the fabric. Ensure its durability and longevity. This structural stability enhances the coating’s ability to maintain its anti-reflective and color-enhancing properties. It also helps improve the overall elasticity and wear resistance of the fabric.
Improve the hydrophilicity of fabrics:
Enhancing the hydrophilicity of fabrics is another significant benefit of this coating fluid. Fabrics treated with this coating have improved moisture absorption and wicking properties. Makes wearing more comfortable. Additionally, this improvement eliminates concerns related to loss of hydrophilicity. This is a common problem with other treatments, such as those involving fluorine and silicone. Unlike these traditional treatments, new coatings do not cause undesirable color changes. Ensure the fabric retains its original color quality. Also benefit from enhanced functionality.
The new coating fluid combines practicality, cost-effectiveness, fabric friendliness, long-term effectiveness, and improved fabric performance. These properties make it an attractive choice for reinforcing polyester fabrics. At the same time, the shortcomings of traditional textile processing are solved. Its application not only improves fabric properties. And it is in line with the sustainable and environmentally friendly practices of the textile industry.
The resulting silica-based antireflective coating liquid was applied directly to polyester fabric. During the particle accumulation process, a cross-linking reaction occurs on the alkoxysilane groups on the surface of the silica nanoparticles. Form a stable porous film structure. Adheres to polyester fabric. This significantly reduces light reflection from the fabric surface. Anti-reflective properties are thereby achieved. It also improves the color development of dyes. Enhances color depth and vibrancy. Also improves hygroscopicity.
