PC hardened sheets are made from a polycarbonate substrate with a special hardening coating, achieving 2H hardness, 92% light transmittance, and HB-grade flame retardancy. They are suitable for architectural decoration, industrial protection, and optical equipment. Their abrasion resistance is 3 to 5 times greater than that of standard PC sheets, and they can be customized in thicknesses ranging from 2 to 12 mm and widths up to 3,000 mm to meet the demands of applications requiring high impact resistance and fire resistance.
PC hardened sheets are functional transparent sheets made from polycarbonate (PC) as the base material, with a dense hardened layer formed through surface coating or co-extrusion processes, combining high impact resistance with high surface wear and scratch resistance.
Core Definition and Principles
Essence: While standard PC sheets offer extremely high impact resistance (approximately 250 times that of glass), their surface hardness is low (approximately 2B–3H), making them prone to scratching; Hardened PC sheets address the “prone to scratching” issue by applying inorganic nanocoatings (such as silicon or titanium oxides) to the substrate surface or using plasma modification technology, thereby increasing the surface pencil hardness to 4H–8H.
Processing Methods: Primarily utilizingUV-curable coatings,thermosetting dip coating/spray coating, orin-mold co-extrusion technologies, these methods provide a “hard shell” protective layer to the surface while retaining the inherent toughness of PC; some high-end products feature a double-sided hardened structure.
Key Specifications: Light transmittance typically ranges from88% to 92%, surface hardness can reachH grade or higher, abrasion resistance is more than4 times that of standard PC sheets, and the material exhibits self-extinguishing properties when removed from a flame (Class B1 or UL94 V-0).
PC hardened sheets are panels made from polycarbonate (PC) as the base material, with surface hardness and wear resistance enhanced through a special processing technique. They are widely used in applications requiring high light transmittance, impact resistance, and flame retardancy, such as architectural decoration, industrial protection, and optical equipment. Their key characteristics include high light transmittance of 92%, HB-grade flame retardancy, and available thicknesses ranging from 2 to 12 mm, enabling them to meet the functional requirements of various applications.
I. Technical Principles and Core Components:
PC hardened sheets use polycarbonate resin as the base material, with a hardened coating formed on the surface through a co-extrusion process. This coating typically consists of silicone or acrylic polymers; the density of intermolecular cross-links is enhanced through UV curing or thermal curing technology, thereby increasing the surface hardness to the 2H level (pencil hardness test). The bond between the substrate and the coating must meet optical-grade transparency standards, ensuring a light transmittance of no less than 92% while maintaining the material’s inherent impact resistance. Its flame-retardant properties are achieved through the addition of inorganic flame retardants, meeting the UL94 HB rating standard; the material is capable of self-extinguishing upon contact with an open flame and inhibiting flame spread.
The core of the PC hardened sheet production process is a two-step method consisting of “substrate extrusion + surface hardening coating and curing,” which uses the sol-gel method to form an inorganic-organic hybrid wear-resistant layer on the polycarbonate surface.
II.Core Process Flow
Substrate Preparation: Polycarbonate (PC) pellets, after rigorous drying (moisture content <0.02%), are melted at high temperatures (260–300°C) in an extruder, filtered, and extruded through a die. The extruded material is then cooled and shaped, and annealed to eliminate internal stresses, resulting in the PC impact-resistant sheet substrate.
Pre-treatment: The formed sheets undergo corona treatment or plasma cleaning to remove oil contamination and increase surface energy, ensuring coating adhesion (the surface must be free of die lines and water ripples).
Coating with Curing Solution: In a dust-free environment, a sol-gel curing solution containing organosilicon compounds and metal oxides (such as silicon dioxide and titanium dioxide) is uniformly applied to one or both sides of the substrate using dip coating, roller coating, or spray coating.
Curing and Cross-linking: After coating, the sheets enter a drying tunnel where they undergo gradual heating (typically 80°C–140°C) to evaporate the solvent. The curing agent undergoes a hydrolytic condensation reaction to form a dense, network-like cross-linked structure, completing the physicochemical curing process.
Post-Inspection and Packaging: After cooling, the panels undergo testing for hardness (pencil hardness up to 2H–4H), adhesion (cross-hatch test), light transmittance, and abrasion resistance. Qualified products are covered with a protective film, then cut and packaged.
Key Process Characteristics
Curing Mechanism: Utilizing sol-gel technology, nanoscale inorganic particles are embedded into an organic resin network, balancing high hardness with a certain degree of toughness to prevent brittle cracking typical of pure inorganic layers.
Main Components: The curing solution is typically a mixture of organosilicon resins, fluorotitanate compounds, and alcohol-based solvents; UV absorbers are sometimes added to provide anti-aging properties.
Performance Limitations: The degree of hardening is inversely proportional to flexibility; high hardness (e.g., >3H) causes the sheet to become brittle and difficult to bend. The stability level of mainstream domestic processes ranges from 2H to 4H; claims of 5H or higher often come at the expense of impact resistance.
Environmental Requirements: The coating and curing processes must be conducted in a cleanroom with low dust levels and controlled temperature and humidity to prevent the formation of crystal spots, pinholes, or orange peel defects in the coating.
III. Key Performance Parameters and Applications:
The sheet thickness ranges from 2 to 12 mm, accommodating various structural strength requirements: thicknesses of 2–5 mm are suitable for light-load applications such as interior decoration and display cases; thicknesses of 8–12 mm are used in applications requiring impact resistance, such as outdoor billboards and protective covers for industrial equipment. With a maximum width of 3,000 mm, the product minimizes seams and enhances overall aesthetics. Its optical-grade properties make it an ideal material for applications such as LED displays and optical instruments, while its transparent design further expands its use in architectural applications such as skylights and partition walls.
IV. Processing and Usage Precautions:
During processing, use tungsten carbide or polycrystalline diamond cutting tools, and maintain a cutting speed of 800–1,200 rpm to prevent coating peeling or melting of the substrate. Bending should be performed after heating the material to 150–180°C, with a bending radius greater than 150 times the sheet thickness to prevent cracking of the hardened layer. During installation, avoid direct friction with metal components; it is recommended to use rubber spacers for isolation. When cleaning, use a neutral detergent and a soft cloth; do not use organic solvents or stiff brushes to prevent damage to the coating. For long-term use, periodically check the surface hardness. If scratches deeper than 0.2 mm appear, it is recommended to replace the sheet to ensure safety.
V. Technical Highlights and Industry Applications:
Compared to standard PC sheets, the hardening process increases surface hardness by 3 to 5 times and significantly enhances wear resistance, making the material capable of withstanding scratches from hard objects such as keys and screwdrivers. The flame-retardant rating has been upgraded from V-2 for standard PC sheets to HB, making it more suitable for public spaces with fire safety requirements. Its optical-grade light transmittance and low-dispersion properties enable it to perform exceptionally well in scenarios requiring high-definition displays, such as museum display cases and surgical operating room shadowless lamp shades. Additionally, the sheets can be customized in thickness and width to flexibly accommodate individual needs, making them an important material choice in the fields of industrial design and architectural decoration.