1. Material and structural design
EVOH (ethylene-vinyl alcohol copolymer) multilayer sunscreen bottles adopt a composite structural design, which usually includes the following layers:
Outer layer: Polyethylene (PE) or polypropylene (PP), providing basic support and impact resistance.
Middle layer: EVOH is the core barrier layer, which achieves extremely low gas permeability through intermolecular hydrogen bonds and high crystallinity, effectively isolating oxygen, water vapor and ultraviolet rays.
Adhesive layer: Special resins (such as modified polyolefins) are used to bond different materials to ensure structural stability.
Some high-end products may add a light-shielding layer (such as adding titanium dioxide) or an anti-ultraviolet coating to further enhance the sunscreen protection performance.
2. Performance advantages
High barrier property: EVOH's barrier rate for gases such as oxygen and carbon dioxide far exceeds that of ordinary plastics (such as polyethylene), which can prevent the oxidation and failure of sunscreen ingredients.
Oil resistance and UV resistance: EVOH has excellent tolerance to oils, fragrances and solvents, and is suitable for sunscreen formulas containing oils; it can also block ultraviolet rays from damaging the contents of the bottle.
Safety: EVOH is non-toxic and odorless, and meets food-grade and cosmetic packaging hygiene standards.
Environmental protection: Multilayer bottles containing EVOH can be recycled, but the layers of materials must be separated through a special process.
3. Application scenarios
Sunscreen products: EVOH multilayer bottles are often used in products that require long-term stability, such as high-SPF sunscreens and sunscreen sprays, to prevent ultraviolet rays and oxygen from causing degradation of active ingredients.
Other sensitive cosmetics: such as essences and lotions containing easily oxidized ingredients such as vitamin C and retinol.
4. Precautions for use
Environmental humidity: EVOH's barrier properties may decrease in high humidity environments (>50%), and it is necessary to use a desiccant or optimize the packaging design.
Recycling restrictions: Multilayer composite structures require professional separation and processing, and are difficult to decompose in ordinary recycling processes. It is recommended to choose a brand that supports environmentally friendly recycling.
Summary
EVOH multilayer sunscreen bottles have become an ideal packaging choice for high-end sunscreen products through the composite structure of "PE/adhesive layer/EVOH/adhesive layer/PE", combined with EVOH's high barrier properties, weather resistance and safety. However, its cost is high and recycling is complicated, and it is necessary to balance performance and environmental protection according to product needs.
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