Nonwoven Golssary

A

air laid process

a nonwoven web forming process that pisperses fibers into a fast moving air stream and condenses them onto a moving screen by means of a pressure or vacuum.

ASTM

the acronym for American Society for Testing and Materials International.

B

basis weight

the weight of a unit area of fabric.  Examples are ounces per square yard and grams per square meter.

binder

an adhesive substance used to bind a web of fibers together or bond one web to another.  The adhesive can be a powder, film, fiber, foam, or in liquid form.

bond strength

the amount of force needed to separate layers in a laminate structure or to break the fiber-to-fiber bonds in a nonwoven.

bonding

the process of combining a fiberous web into a nonwoven fabric by using resins or physical means.

C

calendar bonding

thermally bonding a web of loose fibers by passing them through the nip of a pair of calendar rollers, of which one or both are heated.  Plain or patterened rollers may be used.

carded nonwoven

a nonwoven produced from a carded web that has been bonded by one or more technologies to provide fabric integrity.

catalyst

a chemical that changes the rate of a chemical reaction, usually to speed it up, and is not used up.

composite material

a combination of two or more distinct materials having a recognizable interface between them.

converter

an organization that takes nonwoven fabrics supplied in rolls and provides an intermediate processing step, such as slitting, dyeing, coating, printing.  The fabric is then shipped to the finished products manufacturer.

D

denier

the measurement of a weight per unit length of a fiber.  Denier is numerically equal to the weight in grams of 9,000 meters of the material.  Low numbers indicate fine fibers and high numbers indicate more coarse fibers.

dry forming

a process for forming a web from dry fibers by using carding equipment.

E

entanglement

a method of forming a fabric by wrapping and knotting fibers in a web about each other by mechanical means.

extrusion

a process by which a heated polymenr is forced through an orifice to form a molten stream that is cooled to form a filamnet or fiber.

F

fiber

is a class of materials that are continuous filaments or are in discrete elongated peices, similar to lengths of thread (also spelled, fibre).

flashspinning

a modified spunlaid technology in which a polymer/solvent solution is extruded under conditions that rapid solvent evaporation at the spinneret occurs.  The filaments are collected on a moving screen to form a web.

FPM

feet per minute

fusing

melting or bonding together of fibers or fabrics.

G

geotextile

a permeable fabric used in construction projects for the purpose of soil stabilization, sediment control, erosion control, support and drainage.

gsm

grams per square meter

gsy

grams per square yard

H

hot-melt adhesive

a solid material that melts quickly then sets a firm bond upon cooling.

hydrophobic

lacking the affinity for being wetted by water or for absorbing water.

hydrophylic

having an affinity for being wetted by water or for absorbing water.

hydroscopic

or hygroscopic, is the ability to absorb moisture from the atmosphere, a property that fibers have in varying degrees.

I

isotropic

a fabric having the same physical properties in every direction in the plane of a fabric.  It is related to random distribution of fibers in a fabric.

M

mechanical bonding

bonding a web of fibers by entangling them.  This can be achieved by needling, stitching them with fibers or by entangling them by high pressure water jets.

modulus

the amount of force it takes to stretch a material a unit distance.  It is a measure of elasticity.  An extensible material or fiber has a low modulus.  Stiff materials have a high modulus.

N

necking

the narrowing of a fabric when stretched.

nonwoven fabric

a fabric made directly from a web of fiber, without the yarn preparation necessary for weaving and knitting.

O

orientation

the alignment of fibers in a nonwoven.

P

Pascal

a metric unit of pressure used in measuring an air filter's performance.

PET

polyethylene terephthalate is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers.

polyester

is a category of polymers which contain the ester functional group in their main chain.  Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate (PET).

polypropylene

is a thermoplastic polymer used in a wide variety of applications, abbreviated as PP.

PP

is an abreviation for polypropylene.

R

random laying

forming a web in such a way that the fibers or filaments are laid in essentially random directions.  This is accomplished by using an air laid or wet laid process.

rated filter capacity

the specific quantity of fluid that a filter manufacturer recommends can be handled by the filter.

resin bonding

a common method of web bonding by using chemical agents, which may include adhesive resin and solvents.

S

short fiber

staple fiber less than 0.5 inches long.  Typically used in we laid processes, to make fabrics, or as fillers in the absorbent cores of disposable diapers.

spray bonding, spray bonded

a method of binding fibers to form a fabric.  The adhesive binder is sprayed onto the web of fibers and subsequently dried and cured, see resin bonding.

spunbond, spunbonded

a spunlaid technology in which the filaments have been extruded, drawn and laid on a moving screen to form a web.

spunlace bonding, spunlaced bonding

the method of bonding a web by interlocking and entangling the fibers about each other with high velocity streams of water (synonymous with hydroentangling).

surfactant

a chemical additive that changes the surface attraction between two liquids, or between a liquid and a solid, by changing the surface energy of one or both components.  Often added to make nonwovens hydrophyllic.

T

tensile strength

the strength of a material when subjected to either pulling or to compressive stress.  It measures the stress a material can bear without breaking or tearing.  Typically performed using an Instron tester.

thermal bonded, thermobonded

a web of fibers bonded by a thermal bonding process.

through-air bonding

a bonding system that uses high temperature air to fuse the web's fibers.  There are two basic systems:  blowing hot air through the web in a conveyor oven or passing heated air through the web on a rotating drum..

top sheet

the cover stock that is the first layer inside the diaper that touches the body.  The material is permeable allowing body fluids to pass through to a diaper's core.

U

ultrasonic bonding

the use of high frquency sound to generate localized heat through vibration and cause thermoplastic fibers to bond to one another.

V

Van der Waals forces

the force of attraction and repulsion between molecules caused by the electric fields of the electrons (negative) and the nuclei (positive).  The forces of molecular attraction explain why particles adhere to a filter's fiber.