What is the most commonly used polymer substrate in automotive synthetic leather

Technological innovation in automotive interior materials continues unabated, with automotive synthetic leather playing a central role. The performance, durability, tactile feel, and environmental friendliness of this material are all determined by its core component: the polymer substrate. Within the professional automotive interior supply chain, the most mainstream and widely used polymer substrates are primarily concentrated in two systems: polyurethane (PU) and polyvinyl chloride (PVC).

Polyurethane (PU): Synonymous with High Performance and Environmental Protection

In the current automotive market, polyurethane (PU) synthetic leather is undoubtedly the preferred choice for mainstream, high-end applications. The popularity of PU materials is no accident; they offer the best balance of performance between natural leather and traditional plastics.

1. Structure and Advantages: Breathability and Hydrolysis Resistance

The core advantage of PU synthetic leather lies in its microporous structure. PU manufactured using a wet process or the more advanced solvent-free process creates a porous layer similar to natural leather, imparting excellent breathability and moisture absorption. This is crucial for long-term car seats, effectively enhancing ride comfort.

Chemically, automotive-grade PU is typically produced by reacting polyester polyols or polyether polyols with isocyanates. Polyether PU is favored by OEMs for its excellent hydrolysis resistance. Automotive interiors are exposed to high temperature and humidity for extended periods, making hydrolysis resistance a key indicator of a material's service life.

2. Manufacturing Process Upgrades: Solvent-Free PU and TPU

To meet the automotive industry's requirements for low VOCs and environmental protection, traditional wet-process PU (using solvents such as DMF) is being phased out or improved. Current technological focus is shifting to:

Solvent-free PU: Utilizing reactive polyurethane (RPU) or waterborne polyurethane (Waterborne PU) technology, this eliminates the use of organic solvents at the source, significantly reducing VOC emissions from interior trims and meeting stringent air quality standards such as VDA 270/278.

Thermoplastic polyurethane (TPU): TPU offers excellent mechanical properties, wear resistance, and recyclability. In the automotive synthetic leather sector, TPU is often used for high-performance surface coatings or as a substrate, particularly in electric vehicle (EV) interiors, where lightweighting and recyclability are paramount.

Polyvinyl chloride (PVC): Durability and cost-effectiveness

For decades, polyvinyl chloride (PVC) synthetic leather has dominated the mid- and low-end automotive market due to its excellent durability and significant cost-effectiveness.

1. Performance Characteristics: Scratch Resistance and Easy Cleaning

PVC's chemical structure provides excellent scratch resistance, oil resistance, and excellent cleanability. Adjusting the ratio of plasticizers in the formulation allows for flexible control of the material's softness. PVC leather is commonly used in automotive door panels, lower dashboards, and interior applications such as trucks, where durability is paramount.

2. Challenges and Substitution: Environmental Pressure

However, PVC faces a major challenge due to environmental concerns. Traditional PVC production and waste disposal can pose environmental risks, and its production relies on chlorine. Furthermore, phthalate plasticizers, required to achieve softness, are strictly restricted in global automotive interior regulations. As a result, PVC is gradually being replaced by polyurethane (PU) in both high-end and mainstream passenger car applications.

Emerging Substrates and Future Trends

In addition to traditional PU and PVC, the automotive synthetic leather industry is actively exploring new polymer substrates to meet future demands for sustainability, bio-based materials, and the circular economy.

Bio-based PU/PVC: Utilizing renewable resources (such as corn starch and castor oil) to replace some petroleum-based raw materials to produce bio-based polyols reduces the carbon footprint.

Recycled PET Substrates: Using recycled polyethylene terephthalate (PET) as the base fabric for synthetic leather enables the reuse of waste plastics, directly enhancing the product's green supply chain value.