CA2087244C

CA2087244C - Thermally bondable fiber for high strength non-woven fabrics

Info

Publication number: CA2087244C
Application number: CA 2087244
Authority: CA
Inventors: Rakesh K. Gupta; James E. Mallory; Kunihiko Takeuchi
Original assignee: FIBERVISIONS LP
Current assignee: FIBERVISIONS LP
Priority date: 1992-01-13
Filing date: 1993-01-13
Publication date: 2002-06-04
Anticipated expiration: 2013-01-13
Also published as: IL104375A; US5654088A; DE69324280D1; AR247430A1; US5629080A; TW222646B; BR9300132A; AU3118993A; US5888438A; HK1002486A1; EP0552013B1; EP0552013A2; JPH0641812A; JP3349187B2; AU665969B2; CA2087244A1; IL104375A0; US5733646A; ES2131556T3; DE69324280T2

Abstract

Thermobondable fiber of at least one first component of polypropylene having a melt flow rate of 0.5-30, and at least one second component of polypropylene having a melt flow rate of 60-1000.

Description

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This invention relates to polypropylene fibers suitable for use in the manufacture of non-woven fabrics, procesa~es far making them, compositions comprising such fibers, non-woven fabrics containing them, and artie~.os containing these nan-woven fabrics.
The production of polypropylene fibers and filaments usually involves the use of a mix of a single polymer with nominal amounts of stabili2ers and pigments. The mix is melt extruded into fibers and fibrous produeta using conventional commercial processes. Non-woven fabrics are typically made by making a web of the fibers, and than thermally bonding the fibors together when they meet. More specifically, staple 13 fibers era converted into non-wovon fabrics using, for example, a carding machine, and the carded fabric im thermally bonded. Th~ thermal bonding can be achieved using various heating techniqueB, including heating with berated rollers and heating through the use of ultrasonic welding.
Conventional thermally bonded non-woven fabricst exhibit good loft and softnea~s properties, but lees than optimal cross-directional strength,. and less than optimal cross-directional strength in combination with high elongation. Tha strength of the thermally bonded non-woven fabrics depends upon the orientation of the fibers and the inherent strength of the bond points.
over the years, improvements have. been made in fibers which provide mtronger bond strengths. Flow~ver, further improvementm are needed to provide even higher fabric strengths to permit use of these fabrics in today'm high speed converting processes for hygiene products, such as diapers and other types of incontinence products. In particular, there is a neod for a thermally bondable fiber and a resulting non-woven rabric that possess high cross-directional strength and high elongation. Additionally, Char. is a need for a one-step process for making staple fiber known as a "short spin"
process that provides filaments and ~iberm with properties as good as those produced by a two-step process called a "long spin" process.

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Page -2-According to the invention, a fiber is provided comprising at least one poiypropylane having a melt flaw rate of about 0.5-30, and at least one polypropylene having a melt flow rate of about 60-1000.
Preferably, based on the weight of the fiber, the fiber comprises at least about 3.0% by weight of the polypropylene having a melt flaw rate of about o.5-30, and at least about 3.0% by weight of the polypropylene having a melt flow rate of about 60-1000. More preferably, the fiber comprises at to least about 10.0% by weight of the polypropylene having a malt flow rate of about 0.5-30, and at least about 14.0% by weight of the polypropylene having a molt flow rata of about 60-1000.
preferably, the fiber comprises at least one polypropylene having a melt flow rate of about 1-25, and at least one polypropylene having a malt flow rata of about 200 1000.
Preferably, based on the weight of the fiber, the polypropylene having a melt flow rate of about 0.5-30 is present in an amount of about 5-95%, and the polypropylene having a melt flaw rate of about 60-1000 is present in an amount of about 5-93%. More preferably, the fiber comprises about 2-5.% by weight, preferably about 3% by weight, of polypropylene having a melt flow rate of about 0.5-5, preferably about o.s-5.0, and more preferably about 1.0-3.0, about 70-85% by weight, preferably about 75~r by weight, of palypropylens having a melt flow rata o= about 10-20, preferably about i0-15, and about 10-28 % by weight, preferably about 22% by weight, of polypropylene having a melt flow rate of about 3o0-600, preferably about 350-450.
Almo according to the invention, the fiber hea an average rheological polydispersity index of at least about 4.s, preferably at least about 5.0, more preferably about 5.5, and a pre=erred range of about S.o - 7Ø Further, the fiber has a viscoelastic constant of about 1.5-2.0, a fiber elongation of at~least about 2801, a fiber tenacity less than about 2.5 g/denier, and a size less than about 5 dpf. As utilized in this application dpf denotes denier per filament, with denier being defined ae weight in grams per 9, 000 meter length of filament.

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Ths fiber can contain at least one additive, and the at least one additive can comprise at least one stabilizer.
Also according to the invention, a composition is provided comprising at least one polypropylene having a melt flow rate of about o.5-30, preferably, about 1-25, and at least one polypropylene having a malt flow rate of about 60--1000, prafexably, about 200-1000. This compostition can contain similar components and have similar characteristics as the abovs-described Iibar. For example, the composition can have an average rheological polydispersity index of at least about 4.5., preferably of at least about 5.0, more preferably at least about g.5, and a preferred range of about 5.0-7.0, and can contain at least one additive, such as at least one stabilizer.
Also, the composition can comprise, based on the weight of the composition, at least one polypropylene having a melt flow rate of about o.5-30 is present in an amount of about 5-95%, and at least one polypropylene having a melt flow rate of about 60-1000 is present in an amount of about 5-95%.
Preferably, based on the weight of the composition, the composition comprises at least about 3.0% by weight of the polypropylene having a melt flow rata of about o.5-30, and at least about 3.0% by weight of the polypropylene having a malt flow rate of about 60-1000. Mores preferably, the composition comprises at least about 10.0% by weight of the polypropylenQ
having a melt flow rata of about 0.5-30, arid at least about 10.0; by weight of the polypropylene having a melt flow rate of about 60-1000.
Preferably, the composition comprises about 2-5% by 3o weight, preferably about 3% by weight of polypropylene having a melt flow rata of about o.5-5, preferably about 0.8-5, and more preferably about 1.0-3.0, about 70-85% by weight, preferably about 75% by weight, of polypropylene having a melt flow rate of about 10-20, preferably about 10-15, and about 10-28% by weight, preferably about 22% by weight, of polypropylene having a melt flow rate of about 300-600, pref~rably about 350-450.
Tho invention also contemplates providing a fiber comprising a mixture of at least two components, the at least page -4-two components comprising at toast one first component of polypropylene having a malt flow rate of about O.S-30, and at least one second component of polypropylene having a melt rlow rate or about 60-1000, preferably about 200-1000, and an average melt flow rats of about 5-40, preferably about l0-30, and more preferably about 15-25.
Also according to the invention, a polypropylene containing fiber is provided having an average melt flow rate of about 5-40, preferably 10-30 and more preferably about 18-25, and containing at least about 3.0% of at least one polypropylene having a melt flow rate of about 200-1000, and preferably containing at least about 10~ of the at least one polypropylene haring a malt flow rate of about 200-1000.
Also according to the invention, a polypropylene containing fiber is provided having an average rheological polydispersity index of at least about 4.5, preferably of at least about 5.0, more preferably of at least about 5.5, and a preferred ranged of about 5.0 to 7.0, and containing at least about 3.0% of at least one polypropylene having a melt flaw rate of abaut 200-1000, and preferably containing at least about 10$ of the at least one polypropylene having a melt flow rate of about 200-1000. Preferably, the polypropylene containing fiber has an average melt flow rate of about 5-d0, more preferably about 10-30, and most preferably about 15-25.
Also according to the invention, a thermobondable polypropylene fiber is provided comprising componentm having a zero ahaar viscosity of at least about 2.o x 10~ poise, ana a viscoslastic constant of at least about 1.5.
3o Also according to the invention, a thermally bondable fiber is provided having an average rh8ologieal polydispersity index of at least about 5 . 0 , preferably of at least about S . 5 , and a pr~~terred range of about 5.0-7Ø
All of the fibers according to present invention have a substantially uniform morphology, demonstratable by being substantially uniformly stainabls with ruthenium tatroxida.
According to the invention, a process im provided for spinning polypropylene containing filaments comprising melt spinning a polypropylene composition having a broad molecular ~~~'~244 page -5-weight distribution through at least one spinneretts to form molten polypropylene containing filaments; and quenching the molten polypropylene containing fS.laments to obtain polypropylene containing filaments having an average rheological polydispersity index of at least about 5.0, preferably of at least about 5 . 5 , and a preferred range of about 5.0-7Ø
The spinning speed can be about 30 to 200 m~ters per minute, preferably about 80-100 ~aetsrs per minute, and the polypropylene containing filaments can be continuously drawn and crimped, as practiced with the short span process.
Altsrnativ~ly, the spinning speed can be about 500 to 25Do maters per minute, preferably about 1100-2000 meters per minute, and the polypropylene containing filaments can be drawn and crimped at a speed of about 5o to 250 meters per minute, preferably about 150-200 maters per minute, in a second step according to the long spin procass.
The qusnch~.ng according to the process according to the invention can be effected to obtain a substantially immediate cooling of the molten polypropylene containing filamentm as the molten polypropylene containing filamsnta exit the at least one spinnaretts. Preferably, the quanah comprises an air quench having a velocity, for a "short spin" process, of about 10-45 meters/sscond, preferably about 25-35 metsrs/second, and mor~ pxefarably about 30 meters/stacond;
and, for a "long spin" process, of about 1.5-4.0 meters/second, preferably about 2.0 meters/second. The quench air tamp~rature is about 10-40°C, preferably about 15-30°C, and more preferably either about 15-2o°C or about 37°C.
Also according to the invention, a process is provided for spinning polypropylene containing filaments comprising melt spinning a polypropylene containing composition having a broad molecular weight di~rtribution through at least one spinnerstte at a spinning speed of about 30 to 200 meters per minute, preferably about 80-loo meters per minute, to form molten polypropylene containing filaments; and quenching the molten polypropylene containing fllamentm. Preferably, the quenched filaments have an average theological polydispersity index of at least about 4.5, more preferably of at least about 5.0, even more preferably of at least about .5.5, and a preferred range of 5.0-7Ø Preferably, t:he polypropylene containing composition c:omprises at least one polypropylene having a melt flow rate of about 0.5-30, and at least one polypropylene having a melt flow rate of about E>0-1000.
,Also, according to the invention, a process is provided for producing a thermobondable fiber having an average rheological polydispersity index of at least about 4.5, preferably at least about 5.0, and more preferably about 5.0-7.0 which is substantially maintained throughout the process, comprising melt spinning at a speed of 30-200 meters/sec., a polypropylene containing composition having a broad molecular weight distribution with an average rheological polydispersity index of at least about 4.5, preferably of at least about 5.0, more preferably of at least about 5.5, and a preferred range of about 5.0-'.i.0, through at least one spinnerette to form molten polypropylene filaments; and quenching the molten polypropylene filaments under conditions to obtain filaments having an average rheological polydispersity index substantially corresponding to the rheological polydispersity index of the polypropylene containing composition.
Also according to thE: invention, a process is provided for producing a thermobondable fiber having an average rheological polydispersity index of at least about 4.5, preferably of at least about 5.0, more preferably of at 7_east about 5.5, and a preferred range of about 5.0-7.0, which is substantially maintained throughout the process, comprising melt spinning a polypropylene containing composition having ~~ broad molecular weight distribution through at least one spinnerette t:o form molten polypropylene containing filaments; and quenching the rlolten polypropylene containing filaments under conditions to maintain a substantially uniform morphology of the quenched polypropylene c:ontaining filaments having a.n average rheological polydispersity index ;substantially corresponding to the rheological polydispersity index of t:he polypropylene containing composition.
Also according to the invention, a process is provided for spinning polypropylene containing :Filaments comprising melt spinning a polypropylene containing composition having page -~-a broad molecular weight distribution through at least ane spinnerette at a spinning speed of about 30 to 200 meters par minute, preferably 8o to 100 meterm per minute, to form molten polypropylene containing filaments; and quenching the molten polypropylene containing filaments to obtain polypropylene containing filaments having an average theological polydispersity ind~x of at least about 4.5, preferably of at least about 5.0, more preferably of at least about 5.5.
Preferably, the filaments have an elongation greater than about 25o~r. Further, the polypropylene containing composition preferably contains at 1~ast about 3.0%, preferably at least about 10.0%, of at least one polypropylene haying a melt flow rate of about 60-1000, preserably of about 200-1000.
Preferably, the filaments have an average melt flow rate of about 5-40, more preferably an average melt flow rate of about l0-30, and most preferably an average m~lt flow rata of about 15-25.
Also according to the invention, a process is provided for spinning polypropylene containing filaments comprising melt spinning a polypropylene containing composition having a broad molecular weight distribution, and containing at least about 3.0%, preferably at least about 10.0%, of at least one polypropylene having a malt flow rate of about 60-1000, preferably a melt flow rate of about 200-1000, through at least one spinnerette at a spinning speed of about 30 to zoo meters per minute, preferably of about s0-100 meters per minute, to form molten polypropylene containing filaments; and quenching the molten polypropylene containing filaments to obtain polypropylene containing filaments having an averag~
melt flow rate of about 5-40. Preferably, the filaments have an average theological polydisper~ity index of at least about 4.3, more preferably of at least about g.0, even more preferably of at least about 5.5, and an elongation greater than about 250%.
All of the pracasaes of the invention can use the spinning speeds, drawing and crimping, and quenching steps as described throughout the disclosure.
According to the invention, theta is provided a non-wevon material comprising fibers as described above that are 2087244 s Page -8-thermally bonded together, products having at least one layer of a non-woven material according to the present invention; and hygienic product., including diapers, incontinence products and sanitary napkins, comprising at least one liquid impermeable layer, and least one absorbent layer, and at least one non-oven fabric comprising fibers as above-described thermally bonded together. For example, the diaper according to the invention can include an outer impermeable layer, an inner non-woven fabric layer comprising fibers according to the invention, and an intermediate absorbent layer.
Also according to the invention, a non-woven material is provided compri:~ing polypropylene containing fibers having an average melt flow rate of: about 5-40, preferably about 10-30, more preferably about 15-25, and containing at least about 3.0%, preferably at least about 10.00, of at least one polypropylene having a melt flow rate of about 60-1000, preferably a melt flow :rate of about 200-1000 thermally bonded together.
Also according to the invention, a non-woven material is provided comprising polypropy:Lene containing fibers having an average r:heological polydispersity index of at least about 4.5, preferably about 5.0, more preferably about 5.5, and a preferred range of about 5.0-7.0, and containing at least about 3.0%, preferably at least about 10.0%, of at least one polypropylene having a melt flow rate of about 60-1000, preferably having a melt flow rate of about 200-1000, thermally bonded together. Preferably, the polypropylene containing fiber has an average melt flow rate of about 5-40, more preferably about 10-30, and most preferably about 15-25.

Page -8 ( a ) -In one broad aspect, therefore, the present invention relates to a polypropylene composition comprising at least one polypropylene having a melt flow rate of about 0.5-30, and at least one polypropylene having a melt flow rate of about 60-1000.
In another broad aspect, the present invention relates to a fibre comprising at least one polypropylene having a melt flow rate of about 0.5-30, and at least one polypropylene having a melt flow rate of about 60-1000.
In still another broad aspect, the present invention relates to a polypropylene fibre comprising a mixture of at least two components, said at least two components comprising at least one first component of polypropylene having a melt flow rate of about 0.5-30, and at least one second component of polypropylene having a melt flow rate of about 60-1000, and the f fibre having an average melt f low rate of about 5-40.
In a further broad aspect, the present invention relates to a polypropylene fibre, said fibre having an average melt flow rate of about 5-40, comprising at least about 3.0% of at least: one polypropylene having a melt flow rate of about 200-1000.
In yet another broad aspect, the present invention relates to a polypropylene fibre, said fibre having an average Theological polydispersity index of at least about 4.5, said fibre including in its composition at least about 3.0% of at least one polypropylene having a melt flow rate of about 200-1000.
In a further broad aspect, the present invention relates to a polypropylene fibre, said fibre having a zero shear viscosity of at: least about 2.0 x 104 poise, and a viscoelastic constant of at least about 1.50.
,.~ ~ , Page -8(b)-In another bread aspect, the present invention relates to a process for. spinning polypropylene filaments comprising: melt spinning a polypropylene composition having a broad molecular weight distribution through at least one spinneret~te to form molten polypropylene filaments, the polypropylene composition comprises at least one polypropylene having a melt flow rate of about 0.5-30, and at least. one polypropylene having a melt flow rate of about 60-1000; and quenching the molten polypropylene filaments to obtain polypropylene filaments having an average rheological polydispersity index of at least about 5Ø
In yet another broad aspect, the present invention relates to a proces~~ for spinning polypropylene filaments comprising: melt spinning a polypropylene composition having a broad molecular weight distribution through at least one spinnerett:e at a spinning speed of about 30 to 200 meters per minut:e to form molten polypropylene filaments; and quenching the molten polypropylene filaments.
In another broad aspect, the present invention relates to a process for producing thermobondable polypropylene filaments having an average rheological a;5 polydispersity index of at least about 4.5 which is substantially mairat<~ined throughout the process, comprising: melt ~~p:inning a polypropylene composition having a broad molecular weight distribution with an average rheological polydispersity index of at least.
about 4._'> through at Least one spinnerette to form molten polypropylene f_ilam~ants said polypropylene composit:ion including at least: one polypropylene having a melt i_low rate of about 0.5 - 3U and at least one polypropylene _8 ~C~
having a melt flow rate of about 60 - 1000; and quenching the molten polypropylene filaments under conditions to obtain polypropylene filaments having an average rheological polydispersity index of at least about 4.5, preferably, the sp.in.n:ing speed is about 30 to 200 meters per second.
In another broad aspect, the present invention relates to a process. for producing thermobondable polypropylene fila_ne~ruts having substantially uniform morphology, and an average rheological polydispersity index of at least about 4.5 which is substantially maintained throughout the process, comprising: melt spinning a polypropylene composition having a broad molecular weight d.i;~tribution through at least one spinnerette to form molten polypropylene filaments; and quenching the molten polypropylene filaments under conditions to maintain a substantially uniform morphology of the quenched polypropylene filaments having an average rheologic.al polydaspersity index of at least about 9.5.
In still another broad aspect, the present invention relates t.o a process for spinning polypropylene filaments comprising: melt spanning a polypropylene composition having a broad molecular weight distribution, and a;5 containing at least about 3.Oo of at least one polypropylene having a melt flow rate of about 60-1000, through at least one spinnerette at a spinning speed of about 30 to 200 meters per minute to form molten polypropylene filaments; and quenching the molten :30 polypropylene filaments to obtain polypropylene filaments having an average melt flow rate of about 5-40.

_8 (d) _ In another broad aspect, the present invention relates to a non-woven material comprising polypropylene fibres having an average melt :Flow rate of about 5-40 and including in their composition at least about 3.Oo of at least one polypropylene having a melt flow rate of about 60-1000 thermally :bonded together.
In a further :broad aspect, the present invention relates to a non-woven material comprising polypropylene fibres having an average rheological polydispersity index of at least about 4.5, and including in their composition at least about 3.Oo of at least one polypropylene having a melt flow rate o.f about 60-1000, thermally bonded together.
The present invention also relates to personal hygiene articles comprising at least one impermeable layer, at least one absorbant layer, and at least on.e layer of non-woven material comprising a non-woven material comprising polypropylene fibres having an average melt flow rate of about 5-40 and including i.n their composition ate least about 3.Oo of at least one polypropylene having a melt flow rate of about 60-1000 thermally bonded together or a non-woven material comprising polypropylene fibres having an average a;5 rheologic:al polydispersity index of at least about 4..5, and including in t.hE~ir composition at least about 3.0% of at least one polypropylene having a melt flow rate of about 60--1000, thermally bonded together.
The present invention also relates to a personal .30 hygiene article comprising at least one liquid impermeable layer at least one absorbant layer and at least one layer of :nan-woven material produced by a fibre _8 (e) -comprising at least tine polypropylene having a melt flow rate of about 0.5-:30, and at least one polypropylene having a melt flow rate of about 60-1000.
The fibre may comprise at least about 10.00 by weight of said at least one polypropylene having a melt flow rate of about 0.5-30, and at least about 10.00 by weight of said at least one polypropylene having a melt flow rate of about Ei0-1000. Moreover, preferably said at least one polypropylene having a melt flow rate of 0.5-30 comprises at least one polypropylene having a melt flow rate of about 1-25, and said at least one polypropylene having a melt flow rate of about 60-1000 comprises at least one polypropy~_f.ne having a melt flow rate of about 200-1000.
The fibre may comprise about 2-5o by weight of polypropylene having a melt flow rate of about 0.5-5, about 70-~85% by weight of polypropylene having a melt flow rates of about _10-20, and about 10-28 o by weight: of ~,0 polypropylene having a melt flow rate of about 300-600.
The fibre may have an average rheological polydispersity inde:~ of at least about 4.5.
In a further broad aspect, the present invention relates t:o a polypropylene fibre comprising a mixtuz:e of a:5 at least two components, said at least two components comprising at least one first component of polypropylene having a melt flow rate of about 0.5-30, and at least one second component of polypropylene having a melt flow rate of about 60-1000, a:nd the fibre having an average melt .30 flow rate of about:. 5-40.

_8 (f) _ In a further broad aspect, the present invention relates to a polyp.ropy=Lene fibre, said fibre having an average melt flow rate of about 5-40, comprising at least about 3.0% of at least one polypropylene having a melt flow rate of about 200-1000.
In yet another broad aspect, the present invention relates to a polypropy.Lene fibre, said fibre having an average rheologica_L polydispersity index of at least about 4.5, said fibre including in its composition at least about 3.0% of at least one polypropylene having a melt flow rate of about 200-1000. Said .fibre preferably has an average melt flow rate of about 5-40.
In a further braad aspect, the present invention relates to a polypropylene fibre, said fibre having a zero shear viscosity of at least about 2.0 x 10q poiae, and a viscoelastic constant of at least about 1.50.
Said fibre has preferably an average rheological polydispersity index of at least about 5Ø
Moreover, the fibre of the present invention may have a su.bstantialln uniform morphology, and said fibre is substantially uniformly stainable with ruthenium tetroxide.
The present invention also relates to a personal ~;5 hygiene article comprising a thermally bonded non-woven material comprising a fibre produced by spinning polypropylene filaments as follows: melt spinning a polypropylene comb>osition having a broad molecular weight distribution through at least one spinnerette to form ~~0 molten polypropylene filaments, the polypropylene composition comprises at least one polypropylene having a melt flow rate of about 0.5-30, and at least one -8 (g) _ polypropylene having a melt flow rate of about 60-1000;
and quenching the molten polypropylene filaments to obtain polypropylene filaments having an average rheological polydispersity index of at least about 5Ø
The spinning speed may be about 30 to 200 meters per minute.
In a further broad aspect, the present invention relates to a proces~~ for producing thermobondable polypropylene filaments having an average rheological polydispersity index: of at least about 4.5 which is substantially maintained throughout the process, comprising: melt spinning a polypropylene composition having a broad molecular weight distribution with an average rheologica:l po:Lydispersity index of at least about 4.5 through at least one spinnerette to form molten polypropylene filaments said polypropylene composition including at least one polypropylene having a melt flow rate of about 0.5 -- 30 and at least one polypropylene having a melt flow rate of about 60 - 1000; and quenching the molten polypropylene filaments under conditions to obtain polypropylene filaments having an average rheological polydispersity index of at least about 4.5.

_$ ~n~ _ In this process, the spinning speed is preferably about 30 to 200 meters per minute.
In another broad aspect, the present invention relates to a process for producing thermobondable polypropylene filaments having substantially uniform morphology, and an average rheological polydispersity index of at least about 4.5 which is substantially maintained throughout: the process, comprising: melt spinning a polypropylene composition having a broad molecular weight di;>tribution through at least one spinnerette to form molten polypropylene filaments, said polypropylene composition including at least one polypropylene having a melt flow rate of about 0.5 - 30 and at least one po=~_ypropylene having a melt flow rate of about 60 - 1000; and quenching the molten polypropylene filaments under conditions to maintain a substantially uniform morphology o.f the quenched polypropylene filament; having a.n average rheological polydispersi.ty a;0 index of at least about 4.5. Preferably, the spinning speed is about 30 to 200 meters per minute.
The filaments, in the process of the present invention may have an elongation greater than about 2500.
Moreover, the average rheological polydispersity index of <?5 the quenched polypropylene filaments is preferably at least about 4.5. Further, based on the weight of the composition, said composition comprises at least about 3.0% by weight of said at least one polypropylene having a melt f:Low rate «f about 0.5-30, and at least about. 3.Oo :30 by weight of said at least one polypropylene having a melt flow rate of about 60-1000. The polypropylene composition may contain at least about 3.0% of at least one polypropylene having a melt flow rate of about 60-1000.
In another broad aspect, the present invention relates to a process for spinning polypropylene filaments comprising: melt spinning a polypropylene composition having a broad molecular weight distribution, and containing at least about 3.Oo of at least one polypropylene having a melt flow rate of about 60-1000, through a.t least onE: spinnerette at a spinning speed of about 30 to 200 meters per minute to form molten polypropylene filaments; and quenching the molten polypropylene filaments to obtain polypropylene filaments 1.5 having an average mf=_.lt flow rate of about 5-40.
Because the fiber of the present invention provides superior bond strength compared with conventional polypropylene fiber, the non-woven material thus produced exhibits superior cross-directional tensile properties.
a;0 Further, non-woven material produced with the fiber of the present invention has superior elongation, uniformity, loftiness, white coloration and softness, while exhibiting t:h~e above-noted superior mechanical properties.

Page -9-As used herai:n, polypropylene is utilized in its ordinary commercial meaning wherein the polypropylene is a substantially linear molecule. Further, as umed herein, a polypropylene composition includes a material which contains a broad molecular weight distribution of linear polypropylene to enable the obtaining of fibers and filaments which have superior spinning and thermal bonding characteristics.
Moreover, the fibers and filaments of the present invention provide non-wov~n materials of exceptional cross-directional strength, elongation, uniformity, loftinase and softness, by utilizing the disclasod polypropylene compositions including the disclosed linear polypropylene components having a broad molecular weight distribution, whether or not other components are preaont thsroin. Further, as used herein, polypropylene includes homopolymers of propylene, various polymers containing propylene, such as copolymers and terpolymers of propylene, and polypropylene mixtures (including blends and alloys produced by mixing separate batches or forming a blend ~,~-tu) with othsr~ gubstancea and polymer:. For example, the polymer can comprims copolymer: of propylene, and these copolymers can contain various components. Preferably, such copolymer8 include up to about 10 weight % of at least one of ethylene and butene, but can contain varying amounts thereof depending upon the desired fiber ar filament.
Hy practicing the process of the present invention, utilizing spin compositions according to the present invention, fibers and filaments can bs obtained which have superior spinning and thermal bonding characteristics.
Moreover, the fibers and filaments of the present invention provide non-woven m,aterialm of exceptional cross-directional strength, elongation, uniformity, loftiness and softness, by utilizing a material which contains a broad molecular weight distribution of linear polypropylene, whether or not other components are present therein.
The present in~sntion is directed to various forms of fibara, including falamsnt$ and staple fibers. These terms are used in their ordinary commercial meanings. Typically, herein, filaments is used to refer to the continuous fiber on the spinning machines. "staple fiber" is umsd to refer to cut fibers or filaments.. Preferably, for instance, staple fibers for nonwovsn fabrics useful in diapers have lengths of about 1 to 3 inches, more preferably 1.25 to 2 inehso.

page -10-The polypropylene from which tho improved fiber of the present invention can be produced includes at least one polypropylene having a melt flow rate of about o.5-30, preferably about 1-25, and at least one polypropylene having a melt flow rate o= about 60-1000, preferably about 200-1000.
preferably, based on the weight o! the composition, the at least one polypropylene having a melt flow rate or about 0.5-30 is present i.n an amount of about 5-95%, and the at toast one polypropylene having a melt flow rate of about 50-1000 is to present in an amount of about 5-95%.
Preferably, based on the weight o! the composition, the composition comprises at least about 3.0% by weight of the at least one polypropylene having a melt flow rate of about O.s-30, and at least about 3.0% by weight of the at least one polypropylene having a melt flow rate o! about 60-1000. More preferably, based on the weight or the composition, the composition comprimes at least about 10.0% by weight of the at least one polypropylene having a melt flow rate of about 0,5-30, and at least about 10.0% by weight of the at least one 2o polypropylene having a melt flow rate of about 60-1000.
More preferably, the composition comprises about 2-5 %
by weight, preferably, about 3% by weight of polypropylene having a malt flow rats of about 0.5-5, preferably about 0.8-3.0, and more preferably about 1.0-3.0, about 70-85% by weight, preferably about 75$ by weight, of polypropylene having a melt flow rate of about 10-20, preferably about 10-15, and about 10-28% by weight, preferably about 22% by weight of polypropylene having a melt flow rate of about 300-600, preferably about 330-450.
In a particular embodiment of the .invention, the polypropylene fiber can be made by blending at least one polypropylene having a melt flaw rate of about o.5-30, preperably about 1-25, and at least one polypropylene having a melt flow rate of about 60-1000, preferably about 200-1000 to form a composition, and than melt spinning the composition according to known procedures. The melt flow rate (MFR) as demcribed heroin is determined according t4 ASTM D-1238 (condition L;230i~2.16).
The polypropylene to be made into fibers can comprise Page -11-mixtures of more than one polypropylene within each defined MFR range. The melt :flow rate of the mixture used to make the fiber of the present invention, as well as the fiber itself, has an average melt flow rate of about 5-40, preferably about 10-30, and more preferably about 15-25.
While the polypropylenes can be blended to obtain a broad mixture of molecular weights in the polypropylene to be produced into fibers, as an alternative to blending separate polymers to obtain the unique composition of the present invention, the components of the propylene to be produced into fibers can be made in situ by polymerizing propylene with or without ethylene or butane by known multi-reactor procedures, such as disclosed in Seiler and Goller, "Propylene (PP)," KUNSTSTOFFE 80 (1990) 10, pages 1085-1092.
Known processes for making staple fiber include a conventional "two-step long spin" process or "one-step short spin" process. The long spin process involves first melt-extruding fibers at typical spinning speeds of 500 to 1500 meters per minute. Typically, in a second step run at 100 to 250 meters per minute, these fibers are then drawn, crimped, and cut into staple fiber. The one-step short spin process involves conversion from polymer to staple fibers in a single step where typical spinning speeds are in the range of 50 to 200 meters per minute. The productivity of the one-step process is increased with the use of about 5 to 20 times the number of holes in the spinnerette compared to that typically used in the long spin process. For example, spinnerettes for a typical "long spin" process would include approximately 50-4000, preferably approximately 3000-3500 holes, and spinnerettes for a typical "short spin" process would include approximately 4000 to 100,000 holes preferably, about Page -12-30,000-70,000. Typical temperatures for extrusion of the spin melt are about 250-300°C.
Other means of production of fibrous products include well known melt spun and melt blown processes, which provide continuous filaments-based non-woven fabrics and micro-denier staple-based non-woven fabrics, respectively.
The fiber according to the present invention includes the long filamentous fibers made according to well known spun bond processes, as well as staple fibers made by the aforementioned short spin and long spin processes.
The fiber of ths~ present invention has a preferable denier per filament (dpf) of no greater than about 5.0, preferably between about 0.5 and 3Ø
In making the fiber in accordance with the present invention, at least one stabilizer (including antioxidants) is preferably mixed with the polypropylene to be made into a fiber in an amount ranging from about 0.02-1.0 fiber-weight %, preferably about 0.05-0.2 fiber-weight %, in order to prevent deterioration of the fiber after production. Such stabilizers are well known in poly-propylene-fiber manufacture and include phenylphosphites (available from General Electric Co. under the name ULTRANOX*626, and from Sandoz Chemical Co. under the name SANDOSTAB* PEP-Q), N,N'-bis-piperidinyl diamine-containing materials (available from Ciba Geigy Corp. under the names CHIMASSORB* 119 and CHIMASSORB 944), and hindered phenolics (available under the names CYANOX* 1790 from American Cyanamid Co. and IRGANOX* 1076 from Ciba Geigy Corp.) The at least one stabilizer can be mixed into the blend of polypropylenes, or can be separately added to polypropylenes that are to be mixed together to form a blend to be produced into fibers.
* Denotes Trade Mark ~os~2~~
Page -13-Optionally, whiteners such as titanium dioxide, inamounts up to about: 2 fiber-weight %, antacids such as calcium stearate, in amounts ranging from about 0.05-0.2 fiber-weight %, colorants, in amounts ranging from 0.01-2.0 and other well known additives are included in the fiber of the present invention. Wetting agents, such as disclosed in U.S. Patent No. 4,578,414 are also usefully incorporated into the fiber of the present invention. Other commercially available useful additives include IRGAFOS* 168 (available from American Cyanamid Co.), and LUPERSOL* 101 (available from Pennwalt Corp.).
In making the fiber of the present invention, the polypropylene to be made into a fiber preferably includes about 5-95 fiber-weight % of polypropylene having a melt f low rate of about 0 . 5-3 0 , and about 5-95 f fiber weight ~
polypropylene having a melt flow rate of about 60-1000.
Preferably, based on the weight of the composition, the at least one polypropylene having a melt flow rate of about 0.5-30 is present in an amount of about 5-95, and the at least one polypropylen having a melt flow rate of about. 60-1000 is present in an amount of about 5-950. More preferably, the composition comprises about 2-5% by weight, preferably, about 3% by weight, of polypropylene having a melt flow rate of about 0.5-5, preferably about 0.8-5.0, more preferably about 1.0-3.0, about 70-85% by weight, preferably 75% by weight, of polypropylene having a melt flow rate of about 10-20, preferably about 10-15, and about 10-28% by weight, preferably about 22% by weight of polypropylene having a melt flow rate of about 300-600, preferably about 400.
Preferably, the fiber made in accordance with the present invention has an average rheological polydispersity * Denotes Trade Mark Page -13 ( a ) -index (PI) of at least: about 4.5, preferably at least about 5.0, and more preferably between about 5.0 and 7.0 as measured according to Zeichner and Patel, Proceedincts of Second World Congresss of Chemical Engineering Montreal Vol. 6, pp. 333-337 (1981). In accordance with this reference, the dynamic shear property of a small polymeric sample subjected to a small amplitude oscillatory motion.
The sample is held between two parallel plates of 25 millimeters in diameter at a gap of two millimeters. The top plate is attached to a dynamic motor while the bottom plate is attached to a 2000 gm-cm torque transducer of a Rheometrics~R> Dynamic: Spectrometer or Analyzer. The test temperature is held at 200°C. While keeping the bottom plate stationary, a small amplitude oscillatory motion is imposed on the top plate sweeping the frequency range from 0.1 to 500 radian/second. At each frequency, after the transients have died out, the dynamic stress response is separable into in-phase and out-of-phase components of the shearing strain. The dynamic modulus, G', characterizes the in-phase component while the loss modulus, G", characterizes the out-of-phase component of the dynamic stress. For high molecular weight polyolefins, such as polypropylenes, it is observed that these moduli crossover at a point when measured as a function of frequency. This Page -14-crossover modulus is characteri2ad as Gc, and the crossover frequency is characterized by Wc.
The polydispersity index is defined by 1o6/crossover modulus, and is Pound to correlate with the molecular weight 3 distribution, Mw/Mn. Tha crossover frequency correlates inversely with the weight average molecular weight, Mw, for polypropylenes.
Preferably, the fiber of the present invention also has a viacoelastic constant of about 1.5-2Ø The viscoelastic 10 constant (VC) is defined according to the equation Vc r~°/ (Gc/wc) 1'2', where "r~." is the zero shear viscosity in poise, and "Gc/Wc" is the ratio of crossover modulus to crossover treguency in poise, that is (dyne)(sec)/cm2. The values of Gc and we are determined utilizing the dynamic shear procedure 15 described above. However, the zero shear viscosity is determined utilizing a low shear steady shear procedure in which a cone and plats fixture are used as the platens instead of the two parallel plates in the dynamic shear procedure.
More specifically, the cone has a cone angle of 0.1 radian, 20 and both the cone and the plate are 25 mm in diameter. The teen temperature is held at 200°C, as with the dynamic shear procedure. while maintaining the bottom plato stationary, a constant rotational motion is impos~d on the top cone at a constant Shear rate. After an elapsed time, the stress 25 measured by the transducer maintains a constant value. The viscosity is computed from this steady stress, and the imposed shear rate. The zero shear viscosity, r~" is defined as the viscosity of a high molecular weight polymer in which the vimcosity is invariant as a function of shear rate. The zero 30 shear viscosity is moasured by performing thQ shear sweep from a shear rat~ of 0 . 001 sec-~ to 3 . 0 ssa'~ . The zero shear viscosity is obtained in the low shear rate .region, and i,t is the viscosity that has an associated torque greater than 2 gm-cm, and does net vary with shear rate.
35 The filaments and fibers of the present invention have a substantially uniform structure. This structure is different from the sheath-core differential morphology that is associated with the polypropylene filaments and fibers disclosed in EP-A-445,536 to Kozulla, and corresponding subject matter of which was laid open on August 6, 1991 in Canadian Laid-Open Patent: Application No. 2,035,575.
The substantia~.ly uniform morphological structure of the filaments and fibers according to the present invention is 5' c:haracterizable by transmission electron microscopy (TEM:) of .
ruthenium tetroxide (RuOq)-stained fiber thin sections. In this regard, as taught by Trent: et al. , in Mac_romol_ecul_es, vol . 16, TJo. 4, 1983, "Ruthenium Tetroxide staining of Polymers. for hlectron Microscopy", it is well known that the microphology of polymeric materials is dependent on their heat treatment, .
~~omposition, and processing, and that, in turn, mechanical :properties of these materials such as toughness, impact, strength, resilience, fatigue, and fracture strength can be highly sensitive to morphology. Further, this article teaches that transmission electron microscopy is an established technique for the characterization of the structure of heterogeneous polymer system~~ at a high level of resolution; however, it is often necessary to enhance image contrast for polymers by use of a staining agent . Useful. ataining agents for polymers are taught to include osmium tetroxade and ruthenium tetroxide. For the staining of the filament~~ and fibers of the present invention, ruthenium tetroxide is the preferred staining agent.
In the morphological characterization of the present invention, samples of filaments or fibers are stained. with aqueous Ru09, such as a 0.50 (by weight) aqueous solution of ruthenium tetroxide obtainable from Polysciences, Inc., overnight at room temperature. (Whale a liquid stain is utilized in this procedure, staining of the samples with a gaseous stain is also possible.) Stained fibers are embedded in Spurr* epoxy resin and cured overnight at 60°C~. The embedded stained fibers are then thin sectioned. on an ultramacrotome using a diamond knife at room temperature to obtain microtome sections approximately 80 nm thick, which c:an be examined on conventional apparatus, such as a Zeiss*rsM-10 TEM, at 100kV. Energy dispersive x-ray analysis (EDX) was utilized to confirm that the Ru04 had penetrated completely to the center of the fiber.
* i~enotes Trade P-iark Pag4 -16-Fibers that axe produced according to sheath-core differential morphology of the above-referenced Kozulla applications show an enrichment of the ruthenium on the outsidm surface of the fiber (Ru residue), and on the outer sheath (approxf.mately l~cm) of the fiber cross-section.
further, the coz:e of these Kozulla fibers show a much lower ruthenium content, rn contrast, fibers that are produced according to t:he present invention have a more uniform distribution of ruthenium across the fiber cross-section than 1.0 the fiber produced according to the sheath-core differential ' marph.ology of Kozulla, and da. not illustrate a sheath-core differential morphology.
It im also preferred that the fiber of the present invention have n: tenacity no greater than about 2.5 g/deniar, and a fiber elor.~gation o= at least about 250, as measured on individual fibers using a FAF'EGRAPH* tsnssils tester with a fiber gauge length of about 1.25 c1n and an extension rate of about 200%/min Z;avsrags of l0 fibers tasted) . Fiber tenacity im defined as the breaking force divided by the denier of the fiber, while fiber elongation is defined as the % elongation to break.
As discussed above, the present invention provides non-woven materials including th~ fibers according to the present invention.therm.ally bonded together. By incorporating the fibers of the pra~esnt invention into non-woven materials, non-woven materials of exceptional cross-directional strength and percent elongation can be obtained. These non-woven materials can ba used ass at least one layer in various products, including hygiecnic products, such as diapers, incontinence products and diapers, comprising at least one liquid absorbent layer, at least one liquid impermeable layer and at least one non-woven materia3 layer incorporating fibers of the present invention thsr~ially bonded together. for example, a diaper incorporating a non-woven fabric of the premvcnt invention . 35 would include, as a preferred embodiment, an outermost layer, an~innsr layer of the non-woven material, and at least one intermediate absorbent layer. Of course, a plurality of nan-wovaen material layers and absorbent layore can be incorporated in the diap~r (or other hygienic product) in various * Denotes Trade Mark Pagc -1'7-orientations, and a plurality of outer impermeable layers cah be included ror strength considerations.
In.ordar to more clearly describe the present invention, the following non-limiting examples are provided. All part~
and p~rcentagas~ in the examples are by weight unless indicated .
otherwise.
Fibers (2.:? dpf) are prepared using the one-step short spin process with an inside-out radial quench system. They to spinn.erette contains 64,030 holeas, each having a diameter of 0.35 'mm. Quench air velocity of about 16-30 metere/second and a spj_nning speed of 75 meterg/minute are used. Fibers are crimped at about. 8-12 crimps/cm, coated with a 0.4-0.s fiber-weight% finish mixturo of an ethoxylated fatty acid ester and an ethoxylated alcohol phosphate (available from George A.
Goula~ton Co. , Ins. , Monroe, NC, under the name LUROL* PP 912) , and cut into 3.8 cm long a~taple.
The following polymers are umed. Polymer I is .a homopalymer of propylene having a MFR of 20 and a PI of 4:2.
2o Polymer Iz is a hamopolymer of propylene having a MFR of l0 and a PI of 5.t). Polymer III iS a homopolymer of propylene having a MFR of 18 and a PI oi.4.6 (pv'711*from Himont Canada) .
Polymer IV im a. homopolym~ar of propylene having a MFR of 400 t 40 and a Pa of 3.5 t 0.3 (VALTEC*~HH441 Himont Inc., ~Jilmington Delasware) . Fiber gamplem A-H are proparad using the ~ormulatione and conditions as set forth in the following Table 1. Fiber samples B-F are examples of the present w invention, andl fiber samples A, G, and H are controls.
Additives ~ aria based on fiber weight.
* Denotes Trace Drark -p agB -18 ~'AELE 1 ~i ~ Formulation 5 n Temp. ' G~ Draw Tams. ~ C~

A polymer I 270 ~ 49/3g 0.1$ IRGAF08*168 0.1% calcium ,stearate 0.02% IRGANOX X1076 H 80% polymer II 270 49/32 20% polymer I'V ' 0.06$ ULTRANOX*626 0.05$ calcium stearate 0.01$ IRGANOX 1076 C 80% polymer II 280 51/31 20% polymer IV

0.06% ULTRANOX*626 0.05% calcium staarate 0.01$ IRGANOX 1076 D 90% polymer III ~ 260 51/36 lo% polymer IV

0.06$ ULTRANO~X*626 0.05% calcium atearate o.ol% IRGANOx; lo7s E 85% polymer III 260 54/36 15% polymer I.V .

0.06% ULTRANOX*626 0,05$ calcium stearata 3p 0.01% IRGANO?I: 1076 F 80% polymer I:I 280 51/33 20~r polymer 7:V

0.1% IRGAF09*168 0.05% caloium stearate 0.01% ZRGANOX 1076 G polymer TI 280 49/35 O.l% EHB;

O.Ol% LUPEA90L*lol 0.1% IRGAF09 1b8 O.OS% oalcium ataarata 0.01% IRaANOX 1076 H polymer II 280 49/35 0.1$ EB8 0.01% LUPERBOL*101 ' 0.1% IRGAFOB 168 o.osir ce~laiu~m staarnte go 0.07,$ IRGANO;X 1076 ~Extrud~r :ones temperature.
2FAed-roll temperature/draw-roll temperature.
?bis-(p-etlzylbenzylidene) eorbitol (obtainable fromMitsui Toatsu Chemicala~, Japan).
* T~enotes Txade Mark ~U8724 Pegs -19-The fiber samplem are tainted to determined MFR, PI, and $ elongation as described hareinabove. Fibers from each sample are then made into a non-woven material ( average weight 23.8 g/m2) by thermally bonding a web of the fibers at '75 m/min card bond line speed at a temperature of 15o-loo ° C using a calendar roll having diamond bond points with a total bond area of about 2t7%. Cross-directional (CD) strength of the resulting fabric is determined by testing samples 2.5 cm wide and 1Z.5 cm long that have been cut in the cross direction 1o the fabric production. CD strength is oxprasssd in grams force needed to break the' fabric at the extension rate o~
12.3 cm/min. Fiber and fabric test results (CD strength being for the Fabric) are reported in the following Table 2.
Zero Shoer VSaco Stre- sltZ
H~It Orew n9ih (t0 2 0 S~npls dg/min P.t. Itrtto Sllor~ 9/t~ Potse) VC
27 4.6 l.2x 37t! 56S l.07 t.5s g 18 s.6 1.2X 413 789 2.39 t.78 2 °5 G t8 5.7 t.2x 396 ba3 z.36 1.76 0 2s c.a t.a~x sss bee a zb ~.a t.3sx ~nv aa9 p 20 5.3 t.tx 32~ 762 G d3 3.8 l.ix 330 4 3 0 N 23 4.1 1.3X 30t 49y Comparing results for samplem H-F with controls A, G, and H demonstrates that the fibers of the present invention 35 exhibit superior fabric strength and thermal bonding properties.
~xAMpz.~ a Fibers (2.:: dpt) are prepared using a one-step spinning process with a cross-blow quench system. Spinnerattes 40 contained 30,500 0.3 mm diameter holes. Quench air velocity is about 30~35 tasters per second. The spinr.ir.g speed is 86 maters/minute and the drawing speed is 103 metars/minuta. The fibers are crimped at about 8-12 crimps/cm and cut into 4.s cm long staple during the same process. Polypropylene 45 polymers III and IV of the Example I are used in these experiments. Fiber sample~ J and K are prepared using the formulations and conditions as set forth in the following Table 3. Fiber sample K is an example of the present page -20- ~Ug7244 invention, and fiber sample J is a control. Additiv~m % are based on fiber weight.

F i _b_~r Form > > a ~ s cs,~n din Temn . ' C' Draw Temn . ' C2 J polymer III 235 60/50 0.06~r CYANOX 1790 0.05% calcium stearata 0.1% Ti0 o . oz% rR~Arro~c zo7s to K 95% polymer 7:I2 247 60/60 5% polymer I«
0.085% ULTRANOX 626 0.07% calcium Stearats z5 o.i4% Tio~~~
0.01% IRGANOX 1076 The fiber e~amplas are tested and fabrics made and tested 2o as in Example 1. Results are reported in the following Table 4. Again the CD strength pertains to the fabric and the other raa~ults pertain to the fiber.
Zero 2 5 Sheer CD Viaco Btra~ sicx ~11t Dray ngch ( 10 8aepl dg/min P.1. Ratio Xllonp s/in Potse) VC
J 22 4.3 1.2x' 3~i 600 1.35 1.58 K Z1 4.7 1.2~( 376 660 1.56 1.68 Sample K of the pre~ent invention, which includes a broad molecular weight distribution, exhibits superior properties with respeot to control J. Therefore, in one aspect of the present invention, by having a broad molecular weight dimtribution in the polypropylene composition that is subjected to melt spinning, superior cross-directional properties ars obtained.
E~MpLE 3 Fibers (2.2 dpt) are prepared using a two-step manufacturing process. Fiber spinning is carried out at meters/minute using spinnerettem with 782 0.35 mm diameter holes. Fibers are crimped at 8-12 crimps/cm and cut into 3.s 'Extruder ~.onos temperature.
2Feed-roll temperature/draw-roll temperature.

Pages -21-cm long staple et a drawing speed of 120 meters/minuts.
Polymers II and IV of Example 1 are used. Fiber samples L and M are prepared using tha formulations and conditions as set forth in th~ fol.lowing Table 5. Fiber sample M is a example 5 of the present invention, and fiber sample L iB a control.
Additives % are based on fiber weight.
TAHLE ,5 Fiber Formulas ion Sgin TsnpB ° C~ Draw Temn. ' Cz L polymer II 285 60/60 0.085% ULTRArtOX 625 O.OS% calcium a~toarats 0.1% Ti0 0.008 L~PER:30L 181 15 M 80$ polymer SCI 303 60/60 20% polymer :Cv 0.085% ULTRANOX 626 0.05% calcium stearata 0~Z~ TiO~
The fiber samples ar~ tasted and fabrics made and tested as in Example 1. Results are reported in the following Tables 25 6. Again, the CD strength pertains to the fabric and the other results pertain to the fiber.
Draw % CD
Sample MFR P.I. Ratio Elong Strength 26 ~.2 1.2X 372 410 M 20 5.4 1.2X 506 600 Sample M ~of the present invention exhibits superior properties with respect to control L.
Although the Invention has b:on described with reference to particular means, materials and embodiments, it is to be understood that the invention is not limited to the particulars disclosed and extends to all equivalents within 45 the scope of the claims.
'Extruder ;cones t~mperature.
2Feed-roil temperature/draw-roll temperature.

Claims

1. A polypropylene composition comprising at least one polypropylene having a melt flow rate of about 0.5-30, and at least one polypropylene having a melt flow rate of about 60-1000.

2. The composition according to claim 1, which, based on weight of the composition comprises at least about 3.0%
by weight of said at least one polypropylene having a melt flow rate of about 0.5-30, and at least about 3.0%
by weight of said at least one polypropylene having a melt flow rate of about 60-1000.

3. The composition according to claim 2, which, based on weight of the composition comprises at least about 10.0%
by weight of said at least one polypropylene having a melt flow rate of about 0.5-30, and at least about 10.0%
by weight of said at least one polypropylene having a melt flow rate of about 60-1000.

4. The composition according to claim 1, wherein said at least one polypropylene having a melt flow rate of 0.5-30 comprises at least one polypropylene having a melt flow rate of about 1-25, and said at least one polypropylene having a melt flow rate of about 60-1000 comprises at least one polypropylene having a melt flow rate of about 200-1000.

5. The composition according to claim 2, wherein said at least one polypropylene having a melt flow rate of 0.5-30 comprises at least one polypropylene having a melt flow rate of about 1-25, and said at least one polypropylene having a melt flow rate of about 60-1000 comprises at least one polypropylene having a melt flow rate of about 200-1000.

6. The composition according to claim 1, comprising about 2-5% by weight of polypropylene having a melt flow rate of about 0.5-5, about. 70-85% by weight of polypropylene having a melt flow rate of about 10-20, and about 10-28%
by weight of polypropylene having a melt flow rate of about 300-600.

7. The composition according to any one of claims 1 - 6, having an average rheological polydispersity index of at least about 4.5.

8. A fibre comprising at least one polypropylene having a melt flow rate of about 0.5-30, and at least one polypropylene having a melt flow rate of about 60-1000.

9. The fibre according to claim 8, which, based on weight of the fibre comprises at least about 3.0% by weight of said at least one polypropylene having a melt flow rate of about 0.5-30, and at least about 3.0% by weight of said at least one polypropylene having a melt flow rate of about 60-1000.

10. The fibre according to claim 9, which, based on weight of the fibre comprises at least about 10.0% by weight of said at least one polypropylene having a melt flow rate of about 0.5-30, and at least about 10.0% by weight of said at least one polypropylene having a melt flow rate of about 60-1000.

11. The fibre according to claim 8, wherein said at least one polypropylene having a melt flow rate of 0.5-30 comprises at least one polypropylene having a melt flow rate of about 1-25, and said at least one polypropylene having a melt flow rate of about 60-1000 comprises at least one polypropylene having a melt flow rate of about 200-1000.

12. The fibre according to claim 9, wherein said at least one polypropylene having a melt flow rate of 0.5-30 comprises at least one polypropylene having a melt flow rate of about 1-25, and said at least one polypropylene having a melt flow rate of about 60-1000 comprises at least one polypropylene having a melt flow rate of about 200-1000.

13. The fibre according t:o claim 8, comprising about 2-5% by weight of polypropylene having a melt flow rate of about 0.5-5, about 70-85% by weight of polypropylene having a melt flow rate of about 10-20, and about 10-28% by weight of polypropylene having a melt flow rate of about 300-600.

14. The fibre according to any one of claims 8 - 13, having an average rheoligical polydispersity index of at least about 4.5.

15. A polypropylene fibre comprising a mixture of at least two components, said at least two components comprising at least one first component of polypropylene having a melt flow rate of about 0.5-30, and at least one second component of polypropylene having a melt flow rate of about 60-1000, arid the fibre having an average melt flow rate of about 5-40.

16. A polypropylene fibre, said fibre having an average melt flow rate of about: 5-40, comprising at least about 3.0%
of at least one polypropylene having a melt flow rate of about 200-1000.

17. A polypropylene fibre, said fibre having an average rheological polydispersity index of at least about 4.5, said fibre including in its composition at least about 3.0 % of at least one polypropylene having a melt flow rate of about 200-1000.

18. The polypropylene fibre according to claim 17, wherein said fibre has an average melt flow rate of about 5-40.

19. A thermobondable polypropylene fibre, said fibre having a zero shear viscosity of at least about 2.0 x 10 4 poise, and a viscoelastic constant of at least about 1.50.

20. A polypropylene fibre as claimed in claim 17, said fibre having an average rheological polydispersity index of at least about 5Ø

21. A polypropylene fibre according to any one of claims 15-20, wherein said fibre has a substantially uniform morphology, and said fibre is substantially uniformly stainable with ruthenium tetroxide.

22. A process for spinning polypropylene filaments comprising:
melt spinning a polypropylene composition having a broad molecular weight distribution through at. least one spinnerette to form molten polypropylene filaments, the polypropylene composition comprises at least one polypropylene having a melt flow rate of about 0.5-30, and at least one polypropylene having a melt flow rates of about 60-1000; and quenching the molten polypropylene filaments to obtain polypropylene filaments having an average rheological polydispersity index of at least about 5Ø

23. The process according to claim 22, wherein the spinning speed is about 30 to 200 meters per minute.

24. A process for spinning polypropylene filaments comprising:
melt spinning a polypropylene composition having a broad molecular weight distribution through at least one spinnerette at a spinning speed of about 30 to 200 meters per minute to form molten polypropylene filaments said polypropylene composition including at least one polypropylene having a melt flow rate of about 0.5 - 30 and at least one polypropylene having a melt flow rate of about 60 - 7.000; and quenching the molten polypropylene filaments.

25. The process according to claim 24, wherein the quenched filaments have an average rheological polydispersity index of at least about 4.5.

26. A process for producing thermobondable polypropylene filaments having an average rheological polydispersity index of at least about 4.5 which is substantially maintained throughout the process, comprising:
melt spinning a polypropylene composition having a broad molecular weight distribution with an average rheological polydispersity index of at least about 4.5 through at least one spinnerette to form molten polypropylene filaments said polypropylene composition including at least one polypropylene having a melt flow rate of about 0.5 - 30 and at least one polypropylene having a melt flow rate of about 60 - 1000; and quenching the molten polypropylene filaments under conditions to obtain polypropylene filaments having an average rheological polydispersity index of at least about 4.5.

27. The process according to claim 26, wherein the spinning speed is about 30 to 200 meters per minute.

28. A process for producing thermobondable polypropylene filaments having substantially uniform morphology, and an average rheological polydispersity index of at least about 4.5 which is substantially maintained throughout the process, comprising:
melt spinning a polypropylene composition having a broad molecular weight distribution through at least one spinnerette to form molten polypropylene filaments, said polypropylene composition including at least one polypropylene having a melt flow rate of about 0.5 - 30 and at least one polypropylene having a melt flow rate of about 60 - 1000; and quenching the molten polypropylene filaments under conditions to maintain a substantially uniform morphology of the quenched polypropylene filaments having an average rheological polydispersity index of at least about 4.5.

29. The process according to claim 28, wherein the spinning speed is about 30 to 200 meters per minute.

30. The process according to any one of claims 24 - 29, wherein said filaments have an elongation greater than about 2500.

31. The process according to anyone of claims 24 - 29, wherein the polypropylene composition contains at least about 3.0% of at least one polypropylene having a melt flow rate of about 60-1000.

32. The process according to claim 30, wherein the poly-propylene composition contains at least about 3.0% of at least one polypropylene having a melt flow rate of about 60-1000.

33. A process for spinning polypropylene filaments comprising:
melt spinning a polypropylene composition having a broad molecular weight distribution, and containing at least about 3.0% of at least one polypropylene having a melt flow rate of about 60-1000, through at least one spinnerette at a spinning speed of about 30 to 200 meters per minute to form molten polypropylene filaments; and quenching the molten polypropylene filaments to obtain polypropylene filaments having an average melt flow rate of about 5-40.

34. The process according to claim 33, wherein the average rheological polydispersity index of the quenched polypropylene filaments is at least about 4.5.

35. The process according to any one of claims 22 - 34, wherein, based on the weight of the composition, said composition comprises at least about 3.0% by weight of said at least one polypropylene having a melt flow rate of about 0.5-30, and at least about 3.0% by weight of said at least one polypropylene having a melt flow rate of about 60-1000.

36. A non-woven material comprising polypropylene fibres having an average melt flow rate of about 5-40 and including in their composition at least about 3.0% of at least one polypropylene having a melt flow rate of about 60-1000 thermally bonded together.

37. A non-woven material comprising polypropylene fibres having an average rheological polydispersity index of at least about 4.5, and including in their composition at least about 3.0% of at least one polypropylene having a melt flow rate of about 60-1000, thermally bonded together.

38. A non-woven material comprising fibres as claimed in any one of claims 8 - 21, thermally bonded together.

39. A thermally bondable filament produced by the process of any one of claims 26 - 29.

40. A filament produced by the process of claim 31.

41. A filament produced by the process of claim 32.

42. A filament produced by the process of claim 33.

43. A personal hygiene article comprising at least one liquid impermeable layer, at least one absorbent layer and at least one layer of non-woven material as claimed in claim 36 or 37.

44. A personal hygiene article comprising at least one liquid impermeable layer, at least one absorbent layer and at least one layer of non-woven material as claimed in claim 38.

45. A personal hygiene article comprising a thermally bonded non-woven material. comprising a filament as claimed in claim 39.

46. A personal hygiene article comprising a non-woven material comprising a filament as claimed in claim 40.

47. A personal hygiene article comprising a non-woven material comprising a filament as claimed in claim 41.

48. A personal hygiene article comprising a non-woven material comprising a filament as claimed in claim 42.

49. An article as claimed in claim 43, said article comprising a diaper having an outer impermeable layer, an inner non-woven material layer, and an intermediate absorbent layer.

50. An article as claimed in claim 44, said article comprising a diaper having an outer impermeable layer, an inner non-woven material layer, and an intermediate absorbent layer.

51. An article as claimed in claim 45, said article comprising a diaper having an outer impermeable layer, an inner non-woven material layer, and an intermediate absorbent layer.

52. An article as claimed in claim 46, said article comprising a diaper having an outer impermeable layer, an inner non-woven material layer, and an intermediate absorbent layer.

53. An article as claimed in claim 47, said article comprising a diaper having an outer impermeable layer, an inner non-woven material layer, and an intermediate absorbent layer.

54. An article as claimed in claim 48, said article comprising a diaper having an outer impermeable layer, an inner non-woven material layer, and an intermediate absorbent layer.

55. A fibre according to claim 14, wherein said fibre has a substantially uniform morphology.

56. A process as claimed in any one of claims 22, 23, 25, 26, 27, 28, 29, 30, 34 or 35, further comprising crimping and cutting the filaments so as to form staple fibres.

57. A process as claimed in claim 24, further comprising crimping and cutting the filaments so as to form staple fibres.

58. A process as claimed in claim 31, further comprising crimping and cutting the filaments so as to form a staple fibre.

59. A process as claimed in claim 32, further comprising crimping and cutting the filaments so as to form a staple fibre.

60. A process as claimed in claim 33, further comprising crimping and cutting the filaments so as to form a staple fibre.

61. A process as claimed in any one of claims 22, 23, 25, 26, 27, 28, 29, 30, 34, or 35 wherein said filaments have a substantially uniform morphology and are substantially uniformly stainable with ruthenium tetroxides.

62. A process as claimed in claim 24, wherein said filaments have a substantially uniform morphology and are substantially uniformly stainable with ruthenium tetroxide.

63. A process as claimed in claim 31, wherein said filaments have a substantially uniform morphology and are substantially uniformly stainable with ruthenium tetroxide.

64. A process as claimed in claim 32, wherein said filaments have a substantially uniform morphology and are substantially uniformly stainable with ruthenium tetroxide.

65. A process as claimed in claim 34, wherein said filaments have a substantially uniform morphology and are substantially uniformly stainable with ruthenium tetroxide.

66. A process as claimed in claim 56, wherein said filaments have a substantially uniform morphology and are substantially uniformly stainable with ruthenium tetroxide.

67. A process as claimed in claim 57, wherein said filaments have a substantially uniform morphology and are substantially uniformly stainable with ruthenium tetroxide.

68. A process as claimed in claim 58, wherein said filaments have a substantially uniform morphology and are substantially uniformly stainable with ruthenium tetroxide.

69. A process as claimed in claim 59, wherein said filaments have a substantially uniform morphology and are substantially uniformly stainable with ruthenium tetroxide.

70. A process as claimed in claim 60, wherein said filaments have a substantially uniform morphology and are substantially uniformly stainable with ruthenium tetroxide.