The shelf life of silicone raw materials is closely related to material quality, formula design, storage conditions, and use environment. The lifespan of different types of silicone products varies significantly. The specific analysis is as follows:
1. Material quality: the determining factor of basic lifespan
Food grade/medical grade silicone
Use high-purity raw materials (such as FDA/LFGB certified materials), fully vulcanized, high cross-linking degree, high temperature resistance (-40℃~230℃), and strong anti-aging properties.
Lifespan: Under normal storage conditions, it can reach more than 10 years, or even indefinitely (such as medical implant grade silicone can last 5~10 years in the body).
Case: High-quality silicone spatulas and baking molds have a lifespan of about 5~8 years under high-frequency use; low-frequency use (such as coasters) can reach more than 10 years.
Industrial grade silicone
Used for mechanical accessories, electronic accessories, etc., the design focuses on temperature resistance and pressure resistance.
Lifespan: Under non-human damage, the medium-term and long-term storage performance remains basically unchanged for more than 30 years; normal use (such as silicone tubes) can reach more than 10 years.
2. Formula design: affecting the degree of vulcanization and stability
Curing agent ratio
The amount of curing agent (vulcanizing agent) directly affects the vulcanization speed and cross-linking density.
Low ratio formula (such as 100:2): slow curing speed, long operation time, suitable for machine printing or large-area printing, but the vulcanization may not be sufficient, and it is easy to become sticky and cracked after long-term use.
High ratio formula (such as 10:1): fast curing speed, high cross-linking density, but short operation time, precise control of mixing and printing speed is required, otherwise it is easy to partially cure insufficiently.
Additive type
Silicone oil: increases softness, but excessive amount will reduce wear resistance, solvent resistance and aging resistance (such as the greater the amount of silicone oil added to the pad printing silicone, the softer the rubber head, and the fewer pad printing times).
Anti-aging agent: delays aging caused by environmental factors such as ultraviolet rays and ozone, and extends service life.
3. Storage conditions: slowing down or accelerating performance degradation
Temperature
Silicone has a wide temperature resistance range (-40℃~230℃), but long-term high temperature (such as over 200℃) will accelerate molecular cracking or cross-linking, resulting in softening, deformation or performance degradation.
Recommendation: Keep the storage temperature at 15~30℃ and avoid being close to heat sources (such as stoves and ovens).
Humidity
Silicone has strong hygroscopicity. Long-term exposure to a humid environment will reduce its adsorption capacity and shorten its shelf life.
Data: The general shelf life of silica gel is about 2 years, and it may be less than 1 year in a humid environment.
Recommendation: Store in a dry and ventilated place, avoid folding and squeezing (such as silica gel fresh-keeping bags need to be stored flat).
Light and oxygen
Ultraviolet rays (especially short-wave ultraviolet rays) and ozone will catalyze oxidation reactions, making the surface of silica gel yellow and brittle.
Case: The life of silicone tubes used outdoors may be 30%~50% shorter than that of indoors.
Recommendation: Avoid direct sunlight and store in a cool place.
4. Usage environment: high-frequency use or extreme conditions accelerate loss
High-frequency use
Products that are exposed to high temperature, friction or pulling every day (such as silicone spatulas, fresh-keeping bags) wear out faster.
Lifespan: Usually needs to be replaced every 2 to 3 years. Edge wear and cracking at the handle joint are common loss manifestations.
Extreme conditions
Chemical corrosion: Strong acids, strong alkalis or organic solvents will destroy the molecular structure of silicone, causing expansion, dissolution or cracking.
High temperature and high pressure: Exceeding the upper temperature limit of silicone (such as ordinary silicone ≤200℃, platinum vulcanized silicone ≤250℃) will accelerate aging.
Long-term stress: If the silicone seal is under pressure for a long time, the sealing performance may decrease due to stress relaxation.
V. Differences in the shelf life of special types of silicone
Liquid silicone
The best use period: about 3 months. After more than 6 months, the water evaporates and the silicone precipitates, causing the viscosity to rise and thicken.
Failure standard: After 12 months of placement, the precipitation is serious, the viscosity increases, and there is basically no fluidity and operating performance.
Thermally conductive silicone sheet
Lifespan: Affected by the characteristics of raw materials, processing technology, storage conditions and application environment, the lifespan of products from regular manufacturers can reach about 5 years under normal use conditions.
Failure manifestations: breakage, cracking, corrosion, delamination, blistering, coating shedding, discoloration, wear and tear failure, etc.