The Evolution of Eyeglass Lenses: Advantages of Resin Materials and the Challenges of Polishing

The Evolution of Eyeglass Lenses: Advantages of Resin Materials and the Challenges of Polishing

In today's optical market, most prescription lenses are made from resin materials, having largely replaced the older glass lenses due to their fragility and heaviness. Similarly, most sunglasses utilize lenses made from acrylic or plastic, with some employing resin materials as well. This shift underscores the dominance of resin as the primary material for most eyewear lenses.

For manufacturers of polishing solutions, such as ourselves, it is crucial to understand the specific requirements when formulating polishing slurry for resin lenses. Let’s explore the importance of raw materials in this context.

The raw material preparation workshop focuses on the formulation of monomers and additives, which vary depending on the required refractive index. Leading suppliers in the industry, such as PPG Industries from the United States, Mitsui Chemicals from Japan, and KOC Solution from South Korea, provide essential resin materials. Alongside the primary ingredients, additives like UV powder, colorants, and antioxidants must also be included. This process is akin to a chef's secret recipe; even with the same basic ingredients, variations at this stage significantly impact the quality of the final product.

The process involves using a precision monomer filtering system that performs vacuum and gas extraction. Once prepared, the monomer is transferred to a storage tank, where it is stirred for a certain period before being moved to a casting bucket, followed by vacuum de-gassing before use.

Polishing is a critical post-production process that determines the final optical clarity of the lenses. Resin materials typically have a Mohs hardness of 2 to 3, whereas traditional glass can reach a hardness of up to 5.5. The choice of polishing abrasives is usually dictated by the desired precision of the final product and the hardness of both the material being polished and the abrasives themselves. Consequently, polishing resin lenses presents greater challenges compared to glass, as it is essential to avoid scratching the softer resin while achieving high polishing efficiency.

After extensive testing and adjustments, along with client feedback, our company has opted to use aluminum oxide polishing liquid for resin lenses. This choice strikes a favorable balance between surface finish and polishing speed. Known for its high Mohs hardness of 9, aluminum oxide is an efficient abrasive. When complemented with appropriate chemical additives, we can further enhance the polishing efficiency of our resin lens polishing solutions.

Moreover, we strive to control the particle size and distribution of the aluminum oxide abrasives, ensuring that our final polishing liquid achieves excellent results. This enables rapid polishing of resin lenses while minimizing any potential wear on the material.

As the eyewear industry continues to evolve, understanding the nuances of resin materials and the intricacies of polishing processes remains essential for delivering high-quality optical products.