Silicone materials are widely used in medical, electronic, automotive, food, home and other fields due to their excellent elasticity, temperature resistance, chemical stability and biocompatibility. However, in actual applications, silicone materials may face the following common problems or precautions, which need to be focused on during design, processing and use:
1. Issues related to material performance
Mechanical properties
Insufficient strength: Silicone itself has low strength and is easy to deform or break when stretched, torn or subjected to high pressure.
Hardness selection: Too high hardness will affect elasticity, and too low hardness will not support enough. It is necessary to select the appropriate hardness according to the application scenario (such as 30-70 Shore A commonly used in medical grade).
Poor wear resistance: The surface is easy to wear, and long-term friction may cause material failure.
Temperature resistance
High temperature aging: Long-term exposure to high temperature (>200°C) environment may cause silicone to harden, crack or deteriorate in performance.
Low temperature embrittlement: It may become brittle and lose elasticity at extremely low temperatures (<-50°C).
Chemical stability
Solvent erosion: Some organic solvents (such as ketones and esters) may dissolve or swell silicone.
Acid and alkali corrosion: Strong acid and alkali environments will accelerate the degradation of silicone.
Biocompatibility
Allergic reaction: Inadequately cured silicone may release unreacted low molecular weight substances, causing skin allergies.
Biodegradation: Silicone implanted in the body for a long time may slowly degrade, and attention should be paid to the safety of degradation products.
2. Processing technology related issues
Molding defects
Sink marks, pores: Surface defects caused by poor mold venting or insufficient vulcanization.
Flash and burrs: caused by insufficient mold precision or excessive vulcanization pressure.
Uneven color: caused by uneven dispersion of color paste or fluctuation of vulcanization temperature.
Vulcanization process
Insufficient vulcanization: low material hardness, poor strength, and easy deformation.
Over-vulcanization: The material becomes brittle and the elasticity decreases.
Vulcanizing agent selection: Different vulcanization systems (such as peroxide and platinum) have a significant impact on performance and need to match application requirements.
Secondary processing
Difficult bonding: The surface of silicone is inert, and special adhesives or surface treatments (such as plasma treatment) are required.
Printing/spraying: ink or coating has poor adhesion, so you need to choose a formula with good compatibility.
3. Application scenario related issues
Medical field
Sterilization compatibility: It is necessary to confirm whether the silicone material can withstand high temperature and high pressure (such as 121°C steam sterilization) or chemical sterilization (such as ethylene oxide).
Long-term implantation: It is necessary to evaluate the biological stability of the material to avoid degradation products causing tissue reactions.
Electronic field
Insulation performance: It is necessary to ensure that the insulation resistance of the material is stable under high temperature and high humidity.
Electromagnetic interference (EMI): Transparent silicone may affect the electromagnetic shielding effect, and composite conductive materials are required.
Food contact
Migration test: It is necessary to comply with FDA, LFGB and other regulations to ensure that low molecular weight substances do not migrate into food.
Oil resistance: It may swell when in contact with oil, so you need to choose oil-resistant silicone.
Outdoor use
Weather resistance: Environmental factors such as ultraviolet rays, ozone, and acid rain may cause material aging, and anti-aging agents need to be added.
Color stability: You need to choose pigments with good light resistance to avoid fading.
4. Environmental protection and regulatory issues
Restriction of hazardous substances
RoHS, REACH: Ensure that silicone does not contain harmful heavy metals (such as lead, mercury) or phthalates.
Bisphenol A (BPA): Medical or food contact materials must be BPA-free.
Recyclability
Silicone is difficult to degrade naturally and must be recycled through professional channels after disposal.
5. Precautions for use and maintenance
Cleaning and disinfection
Avoid using strong acids, strong alkalis or organic solvents for cleaning, and give priority to neutral detergents.
Medical-grade silicone must be sterilized according to the manufacturer's recommended method.
Storage conditions
Keep away from light, dry, and away from heat sources, and avoid contact with vulcanizers and heavy metals.
Store in a sealed container to prevent moisture absorption.
Service life
Regularly check material properties, such as changes in elasticity and hardness, and replace aging parts in a timely manner.
6. Strategies for dealing with common problems
Problem Solution
Insufficient strength: Add reinforcing fillers (such as white carbon black), increase hardness or choose high-strength silicone
Poor temperature resistance :Select high-temperature resistant silicone (such as fluorosilicone), optimize the vulcanization process or add a heat insulation layer
Difficult bonding: Use silicone-specific adhesives, plasma treatment or primer treatment
Uneven color: Strictly control the vulcanization temperature, use highly dispersed color paste or premixed masterbatch
Aging cracking: Add anti-aging agents, optimize the formula or apply a protective layer on the surface
Summary
Silicone materials have excellent performance, but the appropriate materials and processes must be selected according to the specific application scenarios. In high-demand fields such as medical and electronics, relevant regulations and standards must be strictly followed to ensure material safety and reliability. At the same time, by optimizing the formula, improving the process and strengthening quality control, common problems can be effectively avoided and the product life can be extended.