Daimler PAPP PWT 7328 Sunscreen Resistance of Indoor Materials

Developed by the Daimler-Benz automotive company, the “Daimler PAPP PWT 7328 Sunscreen Resistance of Interior Materials” standard is a materials testing standard designed to evaluate the sunscreen resistance of vehicle interior materials.

Modern vehicles expose interior surfaces such as seats, instrument panels, door panels, and upholstery to a variety of consumer products. Sunscreen is one of the most common, as it transfers from skin to surfaces in hot weather or during holidays. This standard ensures that materials such as leather, coated textiles, plastics, elastomers, and foils do not degrade, discolor, swell, or lose their physical properties when exposed to typical sunscreen formulations.

This standard is part of Daimler’s broader quality and durability requirements for interior components to maintain long-term appearance, safety, and customer satisfaction.

The following are evaluated using the described test method:

• Resistance to chemical attack from sunscreen components (e.g., UV filters, emollients, alcohols, and fragrances).
• Changes in color, staining, gloss, texture, or surface integrity.
• Potential softening, cracking, or separation of coated or laminated materials.
• Performance on the following different substrate types:
  • Coated textiles and plastic roll products.
  • Leather and leather fiber sheets.
  • Plastics, elastomers, and foils.

In general, the testing method follows these steps:

• A specific amount of standard sunscreen is applied to the test sample.
• The sample is exposed to controlled conditions (temperature, time, and possibly pressure or light).
• The materials remain in contact with the chemical substance for a specific period of time.
• Surface cleaning according to defined protocols.
• Evaluation of visual changes, color fastness (e.g., using grayscale), and mechanical properties before and after exposure.
• Comparing the results with Daimler's acceptance criteria.

Once the test is complete, the following general assessment is made:

• color change
• Surface softening
• Brightness change
• Stickiness
• Layer separation
• Mechanical failure

Other original equipment manufacturers have also developed their own internal standards (e.g., GMW 14445, PV 3964). This reflects the industry-wide concern regarding chemical resistance in vehicle interiors.

Determining the sunscreen resistance of interior materials is important in the automotive industry for the following reasons:

• Aesthetic durability: Prevents unsightly stains or discoloration on premium vehicles.
• Material selection: Helps engineers select or develop coatings, surfaces, and polymers that will withstand real-world use.
• Regulatory and warranty compliance: Daimler contributes to general indoor material approvals under its supply specifications.
• Customer satisfaction: Reduces complaints about sunscreen damage in luxury and high-end models.

This standard is one of many Daimler standards covering mechanical, chemical, and environmental stresses on vehicle components.

In short, the Daimler PAPP PWT 7328 standard focuses on a topic that is becoming increasingly important in modern automotive design: how interior materials react when exposed to sunscreens and cosmetic chemicals.

Automotive interiors are constantly exposed to substances transferred from passengers' skin and clothing. Sunscreens contain oils, UV filters, emulsifiers, and solvents that can damage surfaces over time. Manufacturers have observed the following problems in this regard:

• Sticky or softened plastics
• Brightness changes
• Discoloration
• Surface swelling
• Coating deterioration
• Skin surface damage

Luxury brands like the Mercedes-Benz Group require rigorous durability testing, as their premium interiors must maintain their appearance and durability for many years under real-world usage conditions.

The method described in the PAPP PWT 7328 standard applies to various categories of automotive interior materials, including:

• Skin
• Faux Leather
• Coated textiles
• plastic films
• thermoplastics
• elastomers
• Decorative interior foils

These materials are commonly used in the following areas:

• Seats
• Armrests
• Steering wheels
• Door trims
• Center consoles
• Instrument panel surfaces

This test is often integrated into broader automotive validation programs for interior durability.

The PAPP PWT 7329 standard has become more important for the following reasons:

• Consumers have started using sunscreens with higher sun protection factors more frequently.
• Vehicle cabins are exposed to higher thermal loads.
• The interior surfaces are shifting towards soft-touch coatings and synthetic leather.

Modern UV filter chemicals can aggressively attack polymers and coatings, especially under heat. In parked vehicles, cabin temperatures can exceed 70 degrees Celsius, accelerating chemical interaction between sunscreen and interior materials. As a result, the PAPP PWT 7328 standard is now considered part of advanced automotive material compatibility testing.

The Daimler PAPP PWT 7328 standard is often referenced alongside other Daimler interior material specifications, including the following:

• PAPP PWT 7329 Color change test in amine atmospheres
• DBL 5306 General interior material requirements
• DBL 5471 Interior trim and molded filler specifications.
• MBN 55555 Non-metallic material durability tests

Together, these standards form part of Daimler’s quality control framework for premium automotive interiors.

In conclusion, the Daimler PAPP PWT 7328 standard is a specialized automotive material testing specification designed to evaluate how resistant interior surfaces are to exposure to sunscreen chemicals. It reflects the automotive industry's increasing emphasis on long-term durability, chemical resistance, and luxury interior quality.

Despite being highly technical and primarily used in original equipment manufacturers' supply networks, this standard plays a critical role in ensuring that vehicle interiors maintain their appearance and performance in everyday consumer use.

For many years, our organization, with its competent and experienced team, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services compliant with the Daimler PAPP PWT 7328 standard.