What is the water - vapor transmission rate of PU leather substrate cloth?

The water-vapor transmission rate (WVTR) of PU leather substrate cloth is a crucial property that significantly impacts the performance and suitability of the material for various applications. As a supplier of PU Leather Substrate Cloth, understanding and being able to communicate this characteristic is essential for both our customers and the overall success of the product.

Understanding Water-Vapor Transmission Rate

Water-vapor transmission rate refers to the amount of water vapor that passes through a material over a specific period under defined conditions. It is typically measured in units such as grams per square meter per 24 hours (g/m²/24h). This property is vital because it determines how well a material can allow moisture to escape, which is particularly important in products where breathability is a concern.

In the context of PU leather substrate cloth, a proper WVTR ensures that the final PU leather product can maintain a comfortable micro - environment for the user. For example, in applications like footwear, clothing, and upholstery, a high WVTR can prevent the build - up of sweat and moisture, reducing the risk of odor, skin irritation, and mold growth. On the other hand, a very low WVTR might be desirable in some industrial applications where water - proofing is the primary requirement.

Factors Affecting the WVTR of PU Leather Substrate Cloth

Material Composition

The base fabric of the PU leather substrate cloth plays a significant role in determining the WVTR. Knit Backing Cloth generally has a different WVTR compared to woven fabrics. Knit fabrics often have a more open structure, which allows for better air and moisture passage. The type of fibers used in the base cloth, such as polyester, nylon, or cotton blends, also affects the WVTR. Natural fibers like cotton tend to have higher moisture absorption and can facilitate better water - vapor transmission compared to some synthetic fibers.

PU Coating

The polyurethane (PU) coating applied to the substrate cloth is another critical factor. The thickness, density, and porosity of the PU layer can greatly influence the WVTR. A thinner and more porous PU coating will allow more water vapor to pass through, while a thick and dense coating will act as a barrier, reducing the WVTR. Additionally, the formulation of the PU coating, including additives and cross - linking agents, can be adjusted to modify the WVTR according to specific requirements.

Manufacturing Process

The manufacturing process of the PU leather substrate cloth can impact the WVTR. Processes such as calendering, which involves pressing the fabric between rollers to smooth and compact it, can reduce the porosity of the material and thus lower the WVTR. On the other hand, processes that create a more open or textured surface on the fabric or coating can increase the WVTR.

Measuring the WVTR of PU Leather Substrate Cloth

There are several standard methods for measuring the WVTR of materials, including PU leather substrate cloth. One common method is the cup method, where a sample of the material is sealed over a cup containing a desiccant or water. The cup is then placed in a controlled environment with a specific temperature and humidity. The change in weight of the cup over a set period is measured, and the WVTR is calculated based on the surface area of the sample and the time elapsed.

Another method is the use of automated instruments, such as the Mocon Permatran - W series. These instruments use sensors to measure the rate of water - vapor transmission through the material more accurately and quickly. They can provide real - time data and are suitable for quality control and research purposes.

Importance of WVTR in Different Applications

Footwear

In the footwear industry, a proper WVTR is essential for comfort. If the PU leather substrate cloth used in shoes has a low WVTR, feet can become sweaty and uncomfortable, leading to blisters and an unpleasant smell. A high WVTR allows sweat to evaporate, keeping the feet dry and reducing the risk of fungal infections. Our PU Leather Knit Backing products can be engineered to have an optimal WVTR for different types of footwear, from casual shoes to sports shoes.

Clothing

For clothing applications, especially outerwear and activewear, breathability is a key selling point. A PU leather substrate cloth with a suitable WVTR can ensure that the wearer stays dry and comfortable during physical activities. It allows the body's natural moisture to escape while still providing the protection and style associated with PU leather.

Upholstery

In upholstery, a proper WVTR can prevent the build - up of moisture between the furniture and the user. This is particularly important in areas with high humidity or where the furniture is frequently used. A high WVTR can extend the lifespan of the upholstery by reducing the risk of mold and mildew growth.

Controlling and Optimizing the WVTR

As a supplier of PU leather substrate cloth, we have the expertise to control and optimize the WVTR according to our customers' needs. We can adjust the material composition, PU coating formulation, and manufacturing processes to achieve the desired WVTR. For example, if a customer requires a high - WVTR product for a breathable clothing application, we can use a knit base fabric with a thin and porous PU coating. On the other hand, for a waterproof industrial application, we can use a dense PU coating on a tightly woven base fabric.

We also conduct extensive quality control tests to ensure that the WVTR of our products meets the specified standards. Our in - house laboratories are equipped with the latest measuring instruments, allowing us to accurately measure and verify the WVTR of each batch of products.

Conclusion

The water - vapor transmission rate of PU leather substrate cloth is a complex but crucial property that affects the performance and suitability of the material in various applications. As a supplier, we are committed to providing high - quality products with optimized WVTR to meet the diverse needs of our customers. Whether you are in the footwear, clothing, or upholstery industry, our PU Leather Substrate Cloth products can offer the right balance of breathability, durability, and style.

If you are interested in learning more about our products or discussing your specific requirements, we invite you to contact us for a procurement discussion. Our team of experts is ready to assist you in finding the best solutions for your business.

References

• ASTM E96 - Standard Test Methods for Water Vapor Transmission of Materials
• ISO 15106 - Plastics — Film and sheeting — Determination of water vapour transmission rate