Material changes of Paint Protection Films

Automotive paint protection film, commonly known as clear bra, shields vehicle paint from external damage. Over the past 30 years, the materials used have evolved significantly. Let’s explore this journey of material changes.

Clear Bra Structure

Before diving into the materials, it's important to understand the structure of clear bras, specifically those made from TPU (Thermoplastic Polyurethane). They typically consist of five layers:

1. PET Protective Film: Guards the coating of the clear bra; removed during cutting.
2. Self-Healing Scratch-Resistant Layer: Protects the base material and offers resistance to dirt and stains.
3. Base Layer: Shields vehicle paint from scratches.
4. Adhesive Layer: Bonds the clear bra to the car body.
5. PET Protective Film: Protects the adhesive layer; removed during installation.

Evolution of Clear Bra Materials

Understanding the structure helps highlight the differences between materials and their protective capabilities.

PU (Polyurethane)

Originally derived from military technology, early clear bras were made from PU, known for its toughness but poor tensile strength and stability. PU's susceptibility to yellowing, oxidation, and poor heat resistance led to its discontinuation.

PVC (Polyvinyl Chloride)

Next came PVC clear bras, which shared PU's instability issues. PVC decomposes under high heat, releasing toxic gases and causing yellowing. It also becomes brittle under sunlight, with a lifespan of just 1-2 years. Removal can damage vehicle paint, leading to PVC's decline in popularity.

TPH

TPH films are essentially PVC enhanced with plasticizers. While they offer better anti-yellowing properties, they remain brittle with poor scratch resistance and lack self-healing capabilities. Plasticizer leaching can also damage paint, contradicting the film's protective purpose.

TPEE (Thermoplastic Polyester Elastomer)

TPEE combines the flexibility of rubber with the strength of thermoplastics. It outperforms PVC in elasticity, heat resistance, and durability. However, its natural color limits its use as a transparent clear bra.

TPU (Thermoplastic Polyurethane)

Today’s standard is TPU, known for its excellent performance, recyclability, and environmental benefits. TPU clear bras provide superior elasticity, scratch resistance, and self-healing properties across a broad temperature range (-40°C to 120°C). Nano-coating on TPU films also offers enhanced resistance to dirt and corrosion.

TPU’s popularity is further driven by its installation ease, allowing seamless, no-trace edges. Aromatic TPU may yellow and age, whereas aliphatic TPU is stable and weather-resistant, maintaining clarity and boosting paint gloss by up to 30%. With a lifespan of 5-10 years, TPU clear bras offer great value despite their higher cost compared to PU or PVC.

Material innovation has made PU and similar films obsolete, and we anticipate future advancements that could replace TPU. Stay tuned for our next article on distinguishing different clear bra materials!

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