Finlam provides a variety of waterproof & breathable laminated products. The concept behind this is to provide a laminate that is waterproof to the elements, but still allows moisture vapour to pass through, thus preventing the build up of internal moisture and heat. This is mainly used in protective garments and fabrics, and improves the comfort level for the wearer. Examples of usage are in rainwear, activewear, military jackets, ski-jackets, mattress covers, and footwear.
We offer a variety of Polyurethane, Polyester and PTFE membranes to suit your needs. PVC film can also be substituted if breathability is not a requirement.
Certain applications only require a membrane to act as a barrier with low or no breathability. This can be for waterproofing or windproofing. Finlam carries a range of membranes suitable for this purpose.
It is important when laminating membranes that the correct adhesives are used, as well as appropriate bonding techniques. Inferior adhesives will cause the product to delaminate under certain conditions, e.g. washing or sterilization. Additionally, the quantity of adhesive and how it is applied will have an effect on the breathability. Too much adhesive will form a barrier and reduce the breathability, too little adhesive will result in the fabric delaminating. Finlam Technical has a variety of different adhesives that are designed for specific applications. We have numerous methods of bonding, including a random dot pattern using polyurethane reactive hot melt.
Finlam works primarily with two basic types of breathable waterproof membranes: Microporous and Monolithic/Hydrophilic:
Microporous membranes have very small holes, or pores, which are small enough to allow water vapour to pass through, but prevent larger water droplets from passing. Due to their construction, microporous membranes can not only be used in standard applications that require waterproofing and breathability, but they are also used in specialized filtration applications. Additionally, some microporous membranes are constructed using PTFE, which provides enhanced performance.
Hydrophilic Polyurethane membranes are very widely used in the waterproof breathable market today. PU membranes can offer a very high level of stretch and recoverability, making them very useful for knitted fabrics. These membranes usually have a melt temperature in the range of 140-165c, and can be customized to provide additional performance characteristics such as fire retardant, and resistance to hydrolysis and UV. PU membranes can be sensitive to PH values outside of the 6-8 range.
Polyester membranes are usually monolithic. They are similar to polyurethane membranes but they have less stretch and are able to withstand higher temperatures, ranging up over 200c.
PVC films have little to no breathability. They are used mainly for water and windproofing. They have melt points of about 140-150c. PVC has excellent resistance to UV rays, and to cleaning agents and chemicals with high and low PH values. PVC has an advantage over PU and polyester in its longevity, however it is this same quality that lowers its environmentally friendly score. PVC does not have the same stretch and recovery properties of PU, and is therefore not suitable for applications that require high stretch.
PTFE membranes are microporous. They are significantly more expensive than other membrane types. PTFE membranes are able to withstand extremely high temperatures, some in excess of 400c. This proves useful in firejackets and high temperature filtration products. They are also very resistent to acids and solvents. PTFE does not stretch and recover very well.
BI-Component PTFE membranes were evolved from single-layer PTFE membranes. After numerous washing cycles or exposure to certain oils or fuels, contaminants or detergents can accumulate in the pores of the PTFE membrane. This can compromise the waterproofing. The solution to this is to coat a very thin layer of PU onto the membrane. This does reduce the breathability of the product slightly, but solves the waterproofing problem.
