CA2031812A1

CA2031812A1 - Flame-retardant web with binder filaments

Info

Publication number: CA2031812A1
Application number: CA002031812A
Authority: CA
Inventors: Michael Schops
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1989-12-09
Filing date: 1990-12-07
Publication date: 1991-06-10
Also published as: PT96114A; EP0432620A1; IE904423A1; DE3940713A1; JPH03260155A; KR910012448A

Abstract

Abstract Flame-resistant web with binder filaments There is disclosed a flame-resistant, binder-consolidated spunbonded web formed from load-carrying filaments and binder filaments, the binder filaments comprising a modified polyethylene terephthalate in whose polymer chain phosphorus-containing chain members have been condensed and which as a consequence have permanent flame-resistant properties.

Description

HOECHST ARTIEN OE SELLSCHAFT HOE 89/F 389 Dr. VA/fe Description Flame-retardant web with binder filaments The present invention rel~tes to ~ flame-retardant, ~ binder-consolidated spun~ond~d web ~composed of load-bearing;~filaments~ nd~f~l~me-ret~rdant binder f$~aments made~of a m~o,dified po1yest r. ~ ~
f-is ,Binder-consol1dated~ spunbondeds ~pd fl~me-retardant spunbonded- are already~now Y~
~ Fo~r~inst~nce,~DE-C-22~40~437 and~DE-A-36 42 089 describe D~ 3/~
blnder-conso11dat d ~-punbondedo~in~which not'only the~ 3/~
load-be~rihg fil~ments but ~l~o the~binder fil~ments can Dosc ~7/o~
consist of po1yesters.~The~ spunbonded web described in DE-C-22 40~437 18 based on;relatively co~rse fi1aments of more th~n~8 dtex.~The proportion of bin,der fil~ments is ~, 10-30%, ~prefer~bly between 15-254. In re~peot of the spunbonded web~ described ~in DE-A-36 42 089 filament '"~ ' ,den1-rs of 5 dtex ~nd 12 dtex; are reported in the x ~ 8; the proportion of binder filaments 1~ between lO~and 50%, preferably~between l5 and 304. The b~sis weight Is reported to be gre~ter th~n 120 g/m8.

A similar,spunbonded web~i~ described in DE-A-34 l9 675. G~q~
Th$s~spunbonded~web~, which~is to~be used as a reinforcing c~
yer ~in~roof~-nd ~oallng ~nr-branes, possesse- load-25 ~ be~ring~filament- m~de of poly~thylene terephthalate and c~,q~
, binder filaments made of polybutylene terephthal~te. The ~'~ ~J
p ~ portlon of ~binder filament- is ~upposed to be 10 to 3,0%.~;The Examples record~b~sis weights of 100, 140 and 180 g/mZ,~ fi1-m-nt ~den1ers ~of 4.5 snd 5.6 dtex and blnder~filament~ proportion of 10 to 304.
; . : ~
Low-f1ammab1l1ty~po1yesters ~which cont~in pho~phorus-cont,aining~-compounds'are known for example from FR P~tent 1,196,971~. It~ ~d -cribes~ cOpolyester~ which contain : ~ :
. .

, : ,: .

~: - , .

phosphoric acid units and are fire- and heat-resistant.
These copolyester products can be used as flameproofing and impregnating agents and as adhesives or coatings and also as intermediates. However, sp$nning them into filaments and ~fibers is not possible, since a high phosphorus content causes embrittlement of the products.

It~is also known *o manufacture spunbondeds ~from flame-retardant;poIyesters by incorpor~ting into the polyesters phosphoru~aompounds (for~ -xampIe~poly~pho-phonates or ; 10~ ~ certain phosphoric esters~with~halogen-containing aroma-tic;dihydroxy~cQmpounds) which will~not form~part of the polymer~chaln~ Although u-e of ~such additives led to good,~albeit impermanent, fire~resistance properties, it imposs~ible~to~overlook some~disadvantages which are lS due~in p~rticular to~the~appreciable migration of the additives~within the~polymers.

On the~one h~nd, thl~ make- th~ polymer products toxic to a certain degree; on~the other hand, however, the addi-tives become e~sily removable,~ for example in the course of the dry cleaning of fiber articles produced from the polymer products~.~ A~ a consequence of removal of the additives the polymer~products then of course lose their ~; fl~me-resistant prop rties.

In some ~instances, furthermore, the fairly viscous polymeric~dditive-~ are difficult to mix completely homogeneously with t~he polyesters and, what i8 more, they le-d ~to ~undesirably high qlycol contents if they are added even a8 the polyester is being formed. Compared with polymers which contain P-compounds built lnto the 30~ ~ ~ chain~molecul-s,~ the~polymers which contain P-compounds aB addltive- also have poorer dyeing properties.

All ~the prior art spunbondeds are either relatively he~vyweigh~t, coarse-denler~ products having a compara-tivèly high binder content~but inadequate flame-retardant 35~ ~ properties~, or~else fl~me-resistant polyester spunbondeds ~ ~ , , .~ .

, . ~, . .

which admittedly have proper flame resistant properties but are difficult to process and have unsati-factory textile properties. Polyesters which combine good flame-retardant properties with good spinning and textile properties are described in DE-C-23 46 787. However, ; spunbondeds produced from ~uch modified polyesters, like all purely thermally consolidated spunbondeds, can be made only up to a basis weight of about 50 g/m2, since above this limit an increase in delamination tendency is observed.

Thermoplastic polyesters (specifically polyethylene terephthalate and polybutylene terephthalate) are rela-tively;nonfla~m~ble, since they melt on heating and drip away from the flam*. To manufacture ~punbondeds of high basis weights, therefore, mixtures are frequently used of the two polyesters in which the polybutylene tereph-thalate filament~ serve as binder filaments on ac¢ount of their lower melting point. Surprisingly, however, this leads to a deterioration in the flame-resist~nt proper-ties compared with those of pure polyethylene tereph-thalate spunbondeds.
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It is an ob~ect of the present invention to produce a flame-resistant, binder-con-olidated, low-denier light-weight spunbonded web which has a basis weight of above 50~g/m2, and a high dynamical efficiency, ~.e. a long flex ife.

This ob~ect is achieved by a flame-resistant binder-consolidat-d unmodified polyester, preferably polyethy-lene terephthalate, spunbonded web as cl~ssified at the beginning, wherein the binder filaments are low-flam-mability poly sters formed from dicarboxylic ~nd diol components and containing cocondensed P-containing chain members. Preferably, the basis weight of the spunbonded web is above 50 g/m2, and particularly preferably the load-bearing filaments and the binder filament~ have a linear density within the range between 1 and 7 dtex. The :

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proportion of binder filaments can al80 be below 10% by weight, dependlng on the intended use.

It has been found, surprisingly, that the nove} polyester webs with the specifically modified polyesters as binder filaments possess very good flame-retardant properties, but they can also be manufactured in the form of low-denier lightweight product~ and what is more that they also have good strength properties.
: :
In the case of fiber blend textiles, including those involving polyester fibers, it is a well known fact that the flammabllity rating of the blend fabric can never be predicéed from th fl~mmability rating of the individual components, 80 that the properties of the spunbonded web according to the present invention were not foreseeable.
lS Thls is true of blend fabrics even if they are made low-fla _ able in some way; for instance, polyethylene tereph-thalate is relatively fire-resistant, whereas blend fabrics of polyethylene terephthalate with polybutylene terephthalate binder fibers are surprisingly ~ignifi-cantly more flammable.

The fact that polyester and also cellulose are signifi-cantly less flammable alone than their blend~ is also repeatedly confirmed by the literature (Textilveredelung 8, 1973, page- 310/311).

Preferably, the basis weight of the spunbonded web is between 50 and 200 g/m2, the filament denier between 1 and 10 dtex, in particular 1 and 5 dtex, and the propor-tion of binder filament i8 between 5 and 20 percent by weight. The binder filaments preferably have a smnller denier than the load-bearing filaments.

The load-bearing filaments of the spunbonded webs accor-ding t~ the present invention preferably consist of polyethylene terephthalate. The binder filaments are preferably made of a modified polyethylene terephthalate, ~: ' ., , ' ' .-s for ex~mp}e as described in DE-C-23 46 787, having a corre~pondingly reduced melting point. The melting point of the binder filaments of the spunbonded web ~ccording to the present invention is 20-C, preferably 15-C, below the melting point of the matrix filaments. It i8 nlso very surprising that even such a small difference between the ;melting points of the binder and matrix fllaments nsur ~satisfw tory con~olldatlon~of the webs without as mueh~s lnciplently melting the m~trix fil~ments.

lO~ The~polyesters of the binder filaments consist of dicar-boxylic~ ~cid and diol components~'~together with pho~-phorus-cont~ining chain members whieh eomprise structur~l units~ of the~formula O

R~ 0 ::~ , whieh aceount for about 3-20 mole percent of the ~cid eomponent of the polyester, in which R is~ a saturated, open-ch~in or cyclie alkylene radical of~ preferably 1-15 carbon atoms or nn arylene or~aralkylene~radical and~
20 ~R~ an~alkyl radie-l of ~preferably up to 6 carbon atoms, or~an aryl or aralkyl r~dical.
, Th ~pref-rred dicar~o~ylic w id eomponent is terephthalic w id, but~ other~dlcarboxylic w ids are used ~8 well, pref-r~bly ~8~ coeomponents. Ex~mples are isophthalie acid, 5-sulfoisophthalic~acid,'5-sulfopropoxyisophthalic acid, naphthalene-2,6-dicarboxylic w id, biphenyl-p,p'-~dicarboxylio acid, ~p-phenylene diaeetic acid, 4,4'-oxydibenzoie ~eid, ~diph~:noxy~lkanedicarboxylic acids, trnns-hexahydroterephth~lic~ w id, adipic acid, sebacic 30 '~ w id~nd 1,2-cyclobutanedicarboxylic acid.
Suitable diol components, besides ethylene glycol, ~::
- - . - .
, , .
- ' ~ .

.

~` 20318~2 include as cocomponents for example 1,3-propanediol, 1,4-butanediol and higher homologs of 1,4-butanediol and al~o 2,2-dimethyl-1,3-propanediol, 1,4-cyclohexanedimethanol, etc.

If in addition to a terephthalic acid another one of the abovementioned dicarboxylic acids is used, it is pre-ferably used in an amount not siqnificantly mare than about 10 mole percent of the total acid component. A
~imilar rule applie~ to the composition of the diol component. If here for example a further diol component is used as a cocomponent with ethylene glycol, the amount of the former is preferably li~ewise not significantly more than 10 mol- perc-nt of the total diol component.

In a further embodiment of the invention, the binder fi}ament~ are used to introduce an anti~tat, for example carbon black, into the spunbonded web.

The spunbonded web according to the present invention can be produced by m-ans of any known web formation process, in; particular by one involving the use of a rotating infringement plate and downstream guide surface. The web is preferably laid from successive rows of splnnerets to produce a layered structure composed of load-carrying filaments and ~flame-resistant binder filaments.
Advantageously~, the~two outer layers do not contain any binder filaments.

If th matrix and binder filaments are spun simul-taneously from ad~acent spineret packs or else from a single~ pack, it is important to achieve very uniform intermingling of the two types of fiber in order to ensure a stochastic distribution of the bonds within the mixed web. However, the binder filaments can also be extruded together with the load-carrying filaments in the ; form of combined filam~nts in which the two components are arranged~side by side and which are Gustomarily produced by the spinning/extrusion technique. The .
'.

cross-sections of individual fibers can be varied widely with this technique, being for example round, sickle-shaped or multilobal. This technique and other possible techniques for introducing binder fibers are described for example in DE-A-34 19 637 and DE-C-22 40 437.

Usually, no needling of the laid filaments is nece~sary, only a thermal preconsolidation, followed by a final thermal consolidation, for example with a smooth or an embossed roll. Particularly preferably, thermal con-solidation is effected with hot air, for example in perforated cylinder fixing means, which may be followed by a pair of embossing rolls.

Particularly lofty spunbonded webs are obtained with a minimum proportion of binder filaments and perforated drum fixation. These spunbonded web~ then also have a surface structure of many fiber ends, which distinctly increases the adhesion of coating materials, for example of PVC or bitumen. Such lofty spunbondeds with a fiber-rich surface are also suitable for manufactur~ng filter materials.

The advantages of the sub~ect-matter of the present invention are in particular the following:

1. Unproblematical formation of the spunbonded web from load-carrying filament~ and flame-resistant binder filaments.

2. Low flammability, even from low proportions of flame-re6istant binder filaments.

3. The textile and comfort properties of the spun-bondeds produced from the filaments according to the present invention, compared with those of the correspondinq products which have not been rendered flame-resistant, are as good as unchanged. By contra~t, most known fire-retardant finishes have a 20~18~2 fairly adverse effect on textile structure~ in respect of the properties mentioned.

4. Excellent laundering and drycleaning resistance of the flameproofing.

5. Excellent dyeability of filaments of the spunbonded webs according to the present invention and of textile products produced therefrom, since the flameproofing effect is not due to a superficial finish.
0 6. There i8 no danger of the flameproofing agent being rubbed off.

7. On application of a flame to the web or to textiles manufactured therefrom virtually no melt droplets appear; instead, theproduct becomes only carbonized.
A significant advantage here iB the fact that there is less skin contact with burning material and hence a low risk of burns.

8. Production of fine-denier lightweight spunbondeds.

9. High dynamical efficiency.

Flame-resistant webs can be used in the production of textiles for many purposes, for example for making protective clothing for firefighting and for other types of work at risk from fires (refinery and blast furnace work, welding), as furnishings and curtain fabrics, for upholstery materials, as roof membranes, military fab-rics, tent fabrics and awnings, but also for textile floor coverings or else as components of seat covers in motor vehicles or aircraft.

The addition of antistats - carbon black in the simplest case - in the melt cylinder, moreover, makes it possible to use the spunbonded web according to the present . ~ --` g invention in explosion hazard zones or else aQ a filter medium for clean room~.

Claims

1. A flame-resistant binder-consolidated spunbonded web formed from load-carrying filaments and binder filaments made of polyester, wherein the binder filaments are made of a modified polyethylene terephthalate which has flame-resistant properties.

2. The spunbonded web as claimed in claim 1, having a basis weight of about 50 g/m2, preferably between 50 and 200 g/m2, preferably between 50 and 150 g/m2.

3. The spunbonded web as claimed in at least one of the above claims, wherein the load-carrying filaments and binder filaments have deniers between 1 and 10 dtex, preferably between 1 and 5 dtex.

4. The spunbonded web as claimed in at least one of the above claims, wherein the denier of the binder filaments is less than that of the load-carrying filaments.

5. The spunbonded web as claimed in at least one of the above claims, wherein the proportion of binder filaments is not more than 20% by weight, preferably between 5 and 20% by weight.

6. The spunbonded web as claimed in at least one of the above claims, wherein the load-carrying filaments are made of polyethylene terephthalate.

7. The spunbonded web as claimed in at least one of the above claims, wherein the low-flammability binder filaments are made of polyesters into which phos-phorus-containing chain members have been condensed.

8. The spunbonded web as claimed in at least one of the above claims, wherein the low-flammable binder filements are made of polyesters formed from dicarboxylic acid and diol components and containing as cocondensed units the P-containing chain members comprising structural units of the general formula which account for 3 to 20 mole percent of the acid component of the polyester and in which R is a saturated, open-chain or cyclic alkylene radical or an arylene or aralkylene radical, and R1 is an alkyl radical up to 6 carbon atoms, or an aryl or aralkyl radical.

9. The spunbonded web as claimed in claim 8, wherein in the P-containing structural units R is -CH2-CH2- or -C6H4- and R1 is -CH3 or C6H5.

10. The spunbounded web as claimed in at least one of the above claims, wherein the binder filaments contain an antistat, in particular carbon black.

11. A flame-resistant binder-consolidated spunbonded web as claimed in claim 1 and substantially as described herein.