High-transmittance silicone products have wide applications in optics, electronics, and medical fields. Their performance hinges on the selection of fillers and the optimization of surface treatment technologies. The following systematically analyzes the filler selection and surface treatment strategies for high-transmittance silicone products from multiple perspectives.

Basic Performance Requirements of High-Transmittance Silicone
High-transmittance silicone products need to meet the following core performance indicators:

Light Transmittance:
≥92% transmittance (wavelength 550nm) at a thickness of 1mm
≤1% haze, with impurity content controlled at the ppm level
Refractive index must match application requirements (typically 1.41-1.53)

Weather Resistance:
Wide high and low temperature range resistance (-50℃ to 250℃)
UV aging resistance (no yellowing after 5000 hours)
Resistance to chemical corrosion and oxidation

Mechanical Properties:
High tensile strength and elasticity
Good tear resistance
Low shrinkage and high precision

Processing Performance Good fluidity, can be potted into fine details
Deep curing ability
High requirement for vulcanization uniformity

Filler Selection Strategy
Core Filler Type
Hydrophobic Nano-Silica:
As a core reinforcing filler, it is uniformly dispersed in an alcohol-water dispersion.
Unique sol structure avoids filler agglomeration.
Light transmittance can exceed the 60% limit of conventional silicone rubber.
Dosage range: 10-80 parts, requiring a balance between mechanical properties and optical transparency.

Other Optional Fillers:
Octadecylsilane-bonded silica filler (C18 filler)
Spherical silica normal phase chromatography filler (particle size 2-150μm)
High-purity fumed silica (e.g., Aerosil R972)

Filler Selection Criteria
Parameters Requirements Influence
Particle Size Nanoscale (<100nm) Avoids light scattering, improves light transmittance
Dispersion Uniform dispersion without agglomeration Prevents local light transmittance differences
Surface Properties Hydrophobic treatment Improves compatibility with the matrix
Dosage Optimize ratio Excessive dosage reduces light transmittance.
Surface Treatment Technology
Basic Surface Treatment
Polishing Technology:
Electrolytic Polishing: Surface roughness Ra < 1μm
Mechanical Polishing: Up to Ra 0.008μm
Ultrasonic Polishing: Reduces roughness using abrasive impact
Fluid Polishing: High-speed flowing liquid carries abrasive particles to scour the surface.
Plasma Treatment: Surface bombardment with oxygen/argon plasma
Surface energy increased to 50-60mN/m
Suitable for mass production, long-lasting effect.

Functional Surface Treatment
UV Modification: Special ultraviolet light irradiation causes silicon molecules to float to the surface
Oxidation forms a solid protective layer
Suitable for food-grade and medical-grade products.

Coating Technology:
Anti-aging coatings such as silicone coatings and polyurethane coatings
DLC coating (thickness ≤ 3μm) reduces reflection
Primer coating (e.g., Chemlok) 6100)

Printing and Decoration:
Screen Printing (flat effect, monochrome or multicolor)
Color Printing (heat transfer, water transfer, mold transfer)
UV Printing (high efficiency, fast process)
Epoxy Resin (3D effect)

Synergistic Effect of Fillers and Surface Treatment

Enhanced Dispersion: Surface-treated fillers are more easily and evenly dispersed in the matrix.
Reduces light scattering points and increases light transmittance.

Interface Optimization:
Filler surface treatment improves the adhesion between the filler and the matrix.
Reduces light transmission loss caused by interface defects.

Performance Balance:
Filler selection determines basic performance.
Surface treatment optimizes the final performance. The two work synergistically to achieve a balance between high light transmittance and high performance.
Application Cases and Process Control

LE High-Transparency Silicone:
Uses high-purity LSR raw materials
Strictly controls impurity content (≤0.1% low molecular weight siloxane)
Uses ultra-mirror polished molds (Ra≤0.01μm)

Optical-grade transparent products: Injection speed controlled at 10-30mm/s
Holding pressure 40-60bar
Precisely controlled vulcanization temperature (±1℃)

Precision overmolding process: Mold positioning accuracy ±0.003mm
Avoids "transparent bubbles" (diameter >0.1mm is unacceptable)
Prevents "stress white spots" and "local light transmission differences"

The development of high-transparency silicone products requires comprehensive consideration of material formulation, filler selection, surface treatment processes, and other factors. By optimizing the synergistic effect of filler type and surface treatment technology, high-performance transparent silicone products that meet different application needs can be prepared. With technological advancements, the future application prospects of high-transparency silicone in optics, electronics, and other fields will be even broader.