Types of water proof breathable fabrics
Ø Densely woven fabrics.
Ø Membranes
§ Micro porous membranes.
§ Hydrophilic membranes.
Ø Coating
§ Micro porous coating.
§ Hydrophilic coating.
Ø Combination of micro porous and hydrophilic membranes and coating.
Ø Smart breathable fabrics.
Densely woven fabrics:
1. Ventile:
Ø First effective water proof breathable fabric.
Ø Developed in 1940s for military application.
Ø The finest type of long staple cotton combed ply yearn are used.
Ø Improves regularity.
Ø Ensure that the fibers are as parallel as possible to the yearn axis and there are no large pores where water can penetrate.
Ø Oxford weave (plain weave with two threads acting, together in the warp ) gives minimum crimp in the weft.
Ø When
fabric surface is wetted by water the cotton fibers swell transversely
reducing the size of pores in the fabric and requiring very high
pressure to cause penetration by reducing the pore size.
Ø It has a pore size about 10 micro meter when dry and 3-4 micrometer when wet.
Ø It can protect the water penetration for up to 20 minutes when the water is submerged.
Ø Provide excellent protection against wind , rain, seawater and cold.
Ø Waterproof is provided without the application of any water repellent finishing treatment.
2.Synthetic Microfilament fabric:
Ø Densely woven fabric can also be produced from micro-denier synthetic filament yarns owe their breathability.
Ø Fabrics with very small pores can be engineered by using filament.
Ø Wind proof fabric with an excellent water vapour permeability compared with laminates and coatings.
Ø Microfibers do not actually swell when wet but exhibit very small pores.
Ø Typical pore size for waterproof fabric is about 10 micrometer whereas 60 micrometer for conventional fabrics.
Ø Fabric made from up to 7000 filament per cm.
Membranes:
Ø Membranes
are extremely thin films from polymeric material has high resistance to
liquid water penetration, yet allow r=the passage for water vapour.
Ø A typical membrane is only about 10 micrometer thick.
· Micro Porous membrane.
· Hydrophilic membrane.
Micro Porous Membrane:
Ø First and best known micro porous membrane is Gore-tex, developed by W gore in 1976.
Ø This is a thin film of expanded poly tetrafluroethylene (PTFE) polymer.
Ø Claimed
contain 1.4 million tiny holes per square cm through which water vapour
passes but has high resistance to liquid water penetration.
Ø This hole are smaller (2-3 µm) than the smallest raindrops (100 µm) yet very much large than a water molecule (40 * 10 10-6 µm)
Ø Other manufacturers make similar membranes based on micro porous polyvinylidene fluoride cast directly on the to the fibre.
Ø The hydrogen nature of the polymer and small pore size requires very high pressure to cause water penetration.
Hydrophilic Membrane
Ø Very thin films of chemically modified polyester or polyurethane polymer.
Ø Mon-poromeric.
Ø The polyester or polyurethane polymer is modified by incorporating up to 40% by weight of polyethylene oxide.
Ø Polyethylene
oxide constitutes the hydrophilic part of the membrane and place in the
amorphous region of the polyurethane polymer system.
Methods of incorporation of membrane:
Ø Membranes
have to be incorporated into textile products to maximize the high tech
function without adversely affecting textile properties of handle ,
drape and visual impression.
Ø Methods employed depends on
o Cost.
o Required function.
o Processing condition.
1. Laminate of membrane and outer fabric.
2. Liner or insert processing.
3. Laminate of membrane and lining fabric.
4. Laminate of outer fabric, membrane and lining.
1. Laminate of membrane and outer fabric.
Ø Two layer system.
Ø Membrane is laminated to the undesired of the outer fabric.
Ø Mainly use for making protective clothing.
Ø Very effective protective properties of wind resistance and water proofing.
Ø Reduce aesthetic property by producing s rustling, paper-like handle.
2. Liner or insert processing.
Ø Membrane is laminated to a light weight knitted material or web.
Ø The piece are cut to shape from this material, sewn together and the seams rendered waterproof with special sealing tape.
Ø The structure is then loosely inserted between the outer fabric and the liner.
Ø Used for high thermal insulation and fashion item.
Ø Soft handle.
Ø Good drape.
3. Laminate of membrane and lining fabric.
Ø The laminate is attached to the right side of the lining material.
Ø The functional layer is incorporated into the garments as a separate layer independent to the outer layer.
Ø Fashion aspects can be maximized.
4. Laminate of outer fabric, membrane and lining
Ø Three layer system.
Ø Gives a less attractive handle and drape than other methods.
Ø Is not commonly used.
EVER MPM
Ø Micro porous membrane.
Ø Can be laminated with any kind of fabrics.
Ø Water proof and vapor permeable.
Ø Water proof maintains about 80% after 5 times wash, 70% after 20 times wash.
Ø High strength and soft hand feel after laminating with fabrics.
Ø Non-swelling polyurethane material.
Ø Suitable for golf wear.
1. Feature
Ø Windproof.
Ø High air permeability.
Ø Breathable.
Ø Water resistance.
2. Application
Ø Skiing apparel.
Ø Jackets.
Ø Snow pants.
Ø Work apparel.
Ø Hat.
Ø Gloves.
Coating:
These consists of a layer of polymeric material applied to one surface of the fabric. Polyurethane is used as coating materials.
1. Microporous coating.
2. Hydrophilic coating.
Microporous coating:
Ø Similar structure to the micro porous coating.
Ø Contains very fine interconnected channels, much smaller than the finest raindrop but much larger than a water vapour molecule.
Polyolefin Coating:
Ø POD = polyolefin dispersion in water, suitable for ""standard" application techniques.
Ø PODs have unique advantages:
o Solvent-free solution.
o High solid content.
o Functionalisation possible.
Functionaliasation:
o Possible to mix in active component.
o Examples: FR, antimicrobial, conductive.
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