Note: Descriptions are shown in the official language in which they were submitted.
2031812
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
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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
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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.
.
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,
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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
0 - P - R - C -
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,
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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
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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
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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
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invention in explosion hazard zones or else aQ a filter
medium for clean room~.
