Liquid silicone rubber (LSR) is a high-performance elastomeric material that is widely used in the fields of medical, automotive, electronics, etc. due to its unique chemical structure and processing characteristics. The following is a detailed introduction to its material properties and molding process:
One. Material properties
Temperature resistance
LSR can maintain stability in the range of -50℃ to 200℃, and the short-term temperature resistance can reach more than 250℃, which is suitable for high temperature environment.
Chemical inertness
It has excellent resistance to ultraviolet rays, ozone, acids, alkalis and organic solvents, is not easy to age, and is suitable for long-term outdoor or chemical contact scenes.
Biocompatibility
It has passed FDA, ISO 10993 and other certifications, is non-toxic and odorless, and is widely used in medical devices (such as pacifiers, implants) and food-grade products.
Mechanical properties
The hardness range is usually Shore A 10-80, the tensile strength is 5-12MPa, it has good elasticity and tear resistance, and the performance can be enhanced by fillers (such as silica).
Flowability
Low viscosity liquid properties, suitable for filling complex mold structures, forming thin walls (less than 0.1mm) or precision parts.
Electrical insulation
High dielectric strength (15-20kV/mm), used for cable insulation, electronic packaging, etc.
Two. Molding process
Injection molding
Equipment: a dedicated two-component metering and mixing system to ensure accurate mixing of A/B components (including platinum catalyst and crosslinking agent).
Process parameters: temperature (mold is usually heated to 150-200℃), pressure (10-20MPa) and curing time (several seconds to several minutes) need to be strictly controlled.
Advantages: high efficiency (short cycle), high degree of automation, suitable for mass production.
Casting molding
Suitable for small batches or large products, the mixed rubber is poured into the open mold and cured at room temperature or heating.
Commonly used to make mold prototypes or flexible parts.
Extrusion molding
The continuous products such as pipes and sealing strips are formed by screw extruders, which require subsequent vulcanization (hot air or microwave).
Compression molding
Put the preformed rubber into the mold cavity, pressurize and heat to cure, suitable for thick-walled or special structural parts.
Three. Process precautions
Cleaning requirements: Raw materials must avoid contact with impurities such as sulfur and phosphorus to prevent catalyst poisoning.
Exhaust design: The mold needs to optimize the exhaust groove to avoid bubble defects.
Post-processing: Some products require secondary vulcanization to improve performance.
Four. Application fields
Medical: catheters, breathing masks.
Automotive: seals, cable sheaths.
Liquid silicone rubber combines excellent physical and chemical properties with flexible processing methods, making it an ideal choice for high-end elastomer products.
Consumer electronics: waterproof buttons, wearable device components.
