How can colored sheets maintain high transparency and vibrant colors while achieving high temperature resistance and explosion-proof performance?
Release Time : 2025-12-11
In fields where safety and aesthetics are both critical—such as food packaging, creative stationery, and children's toys—colored sheets have long transcended their traditional "plastic film" status, becoming a key material that integrates visual appeal and engineering reliability. Consumers expect them to be as transparent as glass and as vibrant as printed materials, yet they also demand that they withstand high-temperature sterilization, drops during transportation, and even being torn by children without breaking or scattering. This seemingly contradictory demand is being met through a deep integration of material innovation, structural design, and precision manufacturing processes.
1. High-Performance Substrate: The Physical Basis of Transparency and Toughness
The superior performance of colored sheets stems primarily from the upgrade of the substrate. Traditional PVC, due to its low temperature resistance and tendency to leach plasticizers, has been gradually replaced by APET or PETG. APET boasts a light transmittance exceeding 90% and a heat distortion temperature of 70–85℃, making it suitable for hot-fill food packaging. While PETG is slightly less rigid than APET, it possesses superior impact resistance—its elongation at break can exceed 100%, bending rather than shattering under stress, truly achieving "explosion-proof" safety. These materials are inherently colorless and transparent, providing a pure canvas for subsequent color rendering.
2. Internal Coloring Process: Locking in Vibrancy Without Sacrificing Transparency
To avoid increased haze and decreased abrasion resistance caused by surface printing, high-end colored sheets commonly employ volume coloring technology—uniformly dispersing environmentally friendly organic pigments or dyes within the resin during the melt extrusion stage. This method allows color to naturally shine through from the inside out, maintaining high transparency while ensuring rich, fade-resistant colors. By precisely controlling pigment particle size and concentration, a full spectrum of custom colors, from delicate macarons to highly saturated neon hues, can be achieved, while avoiding the haziness caused by light scattering.
3. Multi-layer Composite Structure: Functional Zoning, Synergistic Effect
Colored sheets often employ a three-layer co-extrusion structure: the middle layer is the main material, while the upper and lower surface layers integrate specific functions. For example, the outer layer adds nano-silica to increase surface hardness, achieving a pencil hardness of 3H or higher, effectively resisting scratches; the inner layer incorporates a permanent antistatic agent to prevent dust adsorption, ensuring the cleanliness of food and electronic stationery. More importantly, some products introduce an elastomer-modified layer on the surface, absorbing energy upon impact, inhibiting crack propagation, and achieving an explosion-proof effect of "tear resistance + splash resistance."
4. High-Temperature Resistance Mechanism: Dual Protection of Molecular Structure and Heat Stabilizers
High-temperature resistance depends not only on the substrate itself but also on the support of a heat stabilization system. The compounding of hindered phenolic primary antioxidants and phosphite secondary antioxidants in the resin can effectively capture free radicals generated during high-temperature processing or use, preventing molecular chain degradation and yellowing. Meanwhile, the crystallization rate is optimized to prevent warping and deformation during pasteurization (or heat-shrink packaging). Actual tests show that high-quality colored sheets can be soaked in 90℃ hot water for 30 minutes without deformation, precipitation, or loss of transparency.
The evolution of colored sheets represents a challenge from materials science to achieve "ultimate balance." It uses molecular-level design to bridge the gap between transparency and color, rigidity and toughness, and aesthetics and safety. When the outer film of a package of candy can both shine with an alluring luster and remain intact after boiling water sterilization, we see not only progress in packaging but also the gentle protection of everyday details by modern polymer engineering.
1. High-Performance Substrate: The Physical Basis of Transparency and Toughness
The superior performance of colored sheets stems primarily from the upgrade of the substrate. Traditional PVC, due to its low temperature resistance and tendency to leach plasticizers, has been gradually replaced by APET or PETG. APET boasts a light transmittance exceeding 90% and a heat distortion temperature of 70–85℃, making it suitable for hot-fill food packaging. While PETG is slightly less rigid than APET, it possesses superior impact resistance—its elongation at break can exceed 100%, bending rather than shattering under stress, truly achieving "explosion-proof" safety. These materials are inherently colorless and transparent, providing a pure canvas for subsequent color rendering.
2. Internal Coloring Process: Locking in Vibrancy Without Sacrificing Transparency
To avoid increased haze and decreased abrasion resistance caused by surface printing, high-end colored sheets commonly employ volume coloring technology—uniformly dispersing environmentally friendly organic pigments or dyes within the resin during the melt extrusion stage. This method allows color to naturally shine through from the inside out, maintaining high transparency while ensuring rich, fade-resistant colors. By precisely controlling pigment particle size and concentration, a full spectrum of custom colors, from delicate macarons to highly saturated neon hues, can be achieved, while avoiding the haziness caused by light scattering.
3. Multi-layer Composite Structure: Functional Zoning, Synergistic Effect
Colored sheets often employ a three-layer co-extrusion structure: the middle layer is the main material, while the upper and lower surface layers integrate specific functions. For example, the outer layer adds nano-silica to increase surface hardness, achieving a pencil hardness of 3H or higher, effectively resisting scratches; the inner layer incorporates a permanent antistatic agent to prevent dust adsorption, ensuring the cleanliness of food and electronic stationery. More importantly, some products introduce an elastomer-modified layer on the surface, absorbing energy upon impact, inhibiting crack propagation, and achieving an explosion-proof effect of "tear resistance + splash resistance."
4. High-Temperature Resistance Mechanism: Dual Protection of Molecular Structure and Heat Stabilizers
High-temperature resistance depends not only on the substrate itself but also on the support of a heat stabilization system. The compounding of hindered phenolic primary antioxidants and phosphite secondary antioxidants in the resin can effectively capture free radicals generated during high-temperature processing or use, preventing molecular chain degradation and yellowing. Meanwhile, the crystallization rate is optimized to prevent warping and deformation during pasteurization (or heat-shrink packaging). Actual tests show that high-quality colored sheets can be soaked in 90℃ hot water for 30 minutes without deformation, precipitation, or loss of transparency.
The evolution of colored sheets represents a challenge from materials science to achieve "ultimate balance." It uses molecular-level design to bridge the gap between transparency and color, rigidity and toughness, and aesthetics and safety. When the outer film of a package of candy can both shine with an alluring luster and remain intact after boiling water sterilization, we see not only progress in packaging but also the gentle protection of everyday details by modern polymer engineering.