Spin finished aramid fibers and use thereof

Novel aramid fibers with a spin finish having useful properties for the production of sheet materials are described in the present application. The aramid fibers contain at least three elements including an anionic antistat based on phosphoric, phosphonic, or phosphoric and phosphonic esters; a compound of the formula .sup.1 --COO--(CH.sub.2 --CH.sub.2 --O--).sub.x --R.sup.2 ; and a compound of the formula R.sup.2 --O--(R.sup.4 --O).sub.y --R.sup.5, wherein R.sup.1 is alkyl or alkenyl, x is an integer from 2 to 20 R.sup.2 is hydrogen or alkyl, R.sup.3 is alkyl or alkenyl, y is an integer from to 8, R.sup.4 is ethylene, propylene, or butylene, and R.sup.5 is alkyl.

BRIEF SUMMARY OF THE INVENTION 
The present invention relates to aramid fibers which have been coated with 
a selected spin finish and to the use of these fibers. 
DESCRIPTION OF THE PRIOR ART 
Aromatic polyamides--also known as aramids--are known fiber-forming 
materials of high chemical resistance. Aramid fibers are notable in 
particular for good mechanical properties, such as high strength and 
moduli. 
Aramid fibers, like other fibers too, are customarily spin finished in 
order that the processing properties in the aftertreatment or further 
processing may be improved. Examples of spin finish systems for aramid 
fibers may be found in WO -A-92-15,747, EP-A-416,486, EP-A-423,703, 
JP-A-49-62,722, JP-A-51-88,798 and JP-A-58-46,179 and also Research 
Disclosures 219,001 and 195,028.

DETAILED DESCRIPTION 
It has now been found that selected spin finishes confer excellent further 
processing properties on aramid fibers. The fibers treated according to 
the present invention exhibit good interfilament cohesion and good 
antistatic properties of the individual filaments. The present invention 
provides spin finishes of low surface or interfacial tension and minimal 
self-color. The spin finishes to be used according to the present 
invention ensure uniform wetting and dispersion on the fiber surface, 
significantly reduce the filament/metal friction, and enable processing at 
elevated temperatures, for example at temperatures of up to 200.degree. C. 
The spin finish system of the present invention is notable for good 
biodegradability; for instance, it is possible to produce spin finishes 
which are more than 80% biodegradable within the meaning of Administrative 
Provision 28 of the German Washing and Cleaning Agents Act. 
The present invention concerns aramid fibers with a spin finish comprising 
A) an anionic antistat based on phosphoric and/or phosphonic esters, 
B) a compound of the formula I 
EQU R.sup.1 --COO--(CH.sub.2 --CH.sub.2 --O--).sub.x --R.sup.2 (I) and 
C) a compound of the formula II 
EQU R.sup.3 --O--(R.sup.4 --O).sub.y --R.sup.5 (II), 
where R.sup.1 is alkyl or alkenyl, x is an integer from 2 to 20, preferably 
3-15, and R.sup.2 is hydrogen or alkyl, R.sup.3 is alkyl or alkenyl, y is 
an integer from 1 to 8, R.sup.4 is ethylene or, when y is 2, 3 or 4, some 
of the R.sup.4 radicals can also be propylene or butylene, and R.sup.5 is 
alkyl, especially methyl. 
The spin finish to be used according to the present invention is applied to 
the aramid fibers in the amount adapted to the particular purpose. This 
amount customarily ranges from 0.2 to 4% by weight, preferably from 0.5 to 
2% by weight, based on the amount of fiber. 
The proportions of the individual components A), B) and C) can be chosen 
within wide limits. 
Component A) is customarily used in amounts from 10 to 40% by weight. 
Component B) is customarily used in amounts from 20 to 60% by weight. 
Component C) is customarily used in amounts from 10 to 40% by weight. 
These amounts are each based on the total amount of components A), B) and 
C) . 
As well as these components A) to C), the aramid fiber spin finishes of the 
present invention may include further ingredients customary for spin 
finishes. Examples are corrosion inhibitors, coloring components, such as 
pigments, biocides and preservatives. 
Component A) can be any desired anionic antistat that contains phosphoric 
and/or phosphonic ester groups. 
Examples are salts of phosphoric esters with monohydric alcohols, 
especially aliphatic alcohols, or salts of phosphonic esters with 
monohydric alcohols, especially alkyl- or aryl-phosphonic esters with 
aliphatic alcohols. The aliphatic alcohols which can be used for preparing 
the phosphoric or phosphonic esters are fatty alcohols with or without 
single or multiple ethylenic unsaturation, especially aliphatic alcohols 
having 10 to 20 carbon atoms, such as decanol, dodecanol, tridecanol, 
tetradecanol, hexadecanol, octadecanol or eicosanol. Furthermore, it is 
also possible to use monohydric alcohols derived from polyalkylene oxides, 
such as polyethylene oxide, polypropylene oxide or polybutylene oxide. The 
number of alkylene oxide repeat units therein can be up to 10. Examples of 
such compounds are to be found in EP-A-423,703. 
Component A) preferably comprises a salt of a mono- or dialkyl phosphate, a 
salt of a mono- or diaryl phosphate, a salt of an alkylphosphonic ester, a 
salt of an arylphosphonic ester or a mixture thereof. 
The salts are compounds with optional cations as counter-ion. Examples of 
preferred cations are alkali metal, alkaline earth metal and quaternary 
ammonium ions, in particular Na.sup.+, K.sup.+, diethanolammonium and 
triethanol-ammonium. 
The alkyl radicals in the mono- or diphosphates and in the phosphonic 
esters can be optional alkyl radicals, which can be straight-chain or 
branched. Customarily they are alkyl radicals having 1-22 carbon atoms. 
Examples of alkyl are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, 
octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, 
hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl and behenyl. 
Ethylenicallyunsaturated radicals are also possible. 
The radicals derived from polyalkylene oxides can be for example radicals 
of the formulae (CH.sub.3 --CH.sub.2 --CH.sub.2 --O)--(CH.sub.2 --CH.sub.2 
--CH.sub.2 --O).sub.s -- or in particular (CH.sub.3 --CH.sub.2 
--O--)--(CH.sub.2 --CH .sub.2 --O).sub.t --, where s and t are each 
integers between 1 and 9. 
The phosphoric or phosphonic esters have particularly preferably at least 
one C.sub.8 --C.sub.20 -alkyl radical. 
The aryl radicals in the mono- or diphosphates and in the phosphonic esters 
can be any desired aromatic radicals, preferably aromatic hydrocarbon 
radicals, especially phenyl. The aryl radicals may also contain one or two 
inert substituents, for example alkyl radicals or halogen atoms. 
The phosphoric and phosphonic esters may contain both alkyl and aryl in the 
same molecule. 
Particularly preferred components A) are alkali metal salts, especially 
sodium or potassium salts, of alkyl alkylphosphonates or especially of 
mono- or dialkyl phosphates. Examples of such compounds are the products 
.sup.R Silastol NZ from Schill und Seilacher GmbH & Co., .sup.R Tallopol 
EM 5198 from Chemische Fabrik Stockhausen GmbH and .sup.R Leomin AN from 
Hoechst AG. 
Component B) of the spin finishes to be used according to the present 
invention is a specific polyethylene glycol ether ester. 
R.sup.1 can be any desired alkyl or alkenyl group. 
Examples of possible alkyl groups are recited above in the description of 
the mono- or diphosphates and phosphonic esters. 
The alkenyl groups can be any desired alkenyl radicals, which can be 
straight-chain or branched. Customarily they are alkenyl radicals having 
2-20 carbon atoms. Examples of alkenyl are ethylene, propenyl, butenyl, 
pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, 
dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, 
heptadecenyl and octadecenyl. 
Particular preference is given to R.sup.1 as C.sub.12 --C.sub.20 -alky1. 
R.sup.2 can be hydrogen or any desired alkyl group. 
Examples of possible alkyl groups are recited above in the description of 
the mono- or diphosphates and the phosphonic esters. 
R.sup.2 is preferably methyl. 
Component C) of the spin finishes to be used according to the present 
invention is a specific polyethylene glycol ether which may additionally 
contain polypropylene glycol and/or polybutylene glycol units. 
R.sup.3 can be any desired alkyl or alkenyl group or the bivalent, 
tervalent or tetravalent radical of an aliphatic alcohol with or without 
ethylenicunsaturation. 
Examples of possible alkyl groups R.sup.3 are recited above in the 
description of the mono- or diphosphates and the phosphonic esters. 
Examples of possible alkyl groups R.sup.3 are recited above in the 
description of R.sup.1. 
Examples of polyhydric alcohols from which R.sup.3 can be derived are 
glycol, glycerol, trimethylolpropane and pentaerythritol. 
Particular preference is given to R.sup.3 as C.sub.12 -C.sub.20 -alkyl. 
Particular preference is given to R.sup.3 being derived from a monohydric 
alcohol (y=1). 
R.sup.4 is customarily a polyethylene glycol radical; in the case of a 
tervalent or tetravalent alcohol radical R.sup.3, polybutylene glycol 
radicals or preferably polypropylene glycol radicals can be additionally 
present in the molecule. 
R.sup.5 can be any desired alkyl group. 
Examples of possible alkyl groups R.sup.5 are recited above in the 
description of the mono- or diphosphates and the phosphonic esters. 
R.sup.5 is preferably methyl. 
The fiber of the present invention can be made of any desired aramids. 
These aramids can be essentially composed of meta-aromatic monomers. An 
example of compounds of this type is poly(meta-phenyleneisophthalamide). 
The fiber-forming material preferably comprises aramids composed to a 
significant proportion of para-aromatic monomers. Some of these aramids 
are insoluble in organic solvents and are therefore usually spun from 
sulfuric acid. An example of compounds of this type is 
poly(paraphenyleneterephthalamide). 
A further preferred group of this type is soluble in organic solvents, 
especially in polar aprotic solvents. 
A soluble aromatic polyamide for the purposes of this invention is any 
aromatic polyamide which has a solubility in N-methylpyrrolidone of at 
least 50 g/l at 25.degree. C. 
The polar aprotic organic solvent preferably comprises at least one solvent 
of the amide type, for example N-methyl-2-pyrrolidone, 
N,N-dimethylacetamide, tetramethylurea, N-methyl -2-piperidone, 
N,N'-dimethylethyleneurea, N,N,N',N'-tetramethylmaleamide, 
N-methylcaprolactam, N-acetylpyrrolidine, N,N-diethylacetamide, 
N-ethyl-2-pyrrolidone, N,N'-dimethylpropionamide, 
N,N-dimethylisobutylamide, N-methylformamide, N,N'-dimethylpropyleneurea. 
The preferred organic solvents for the process of the present invention 
are N-methyl-2-pyrrolidone, N,N-dimethylacetamide and a mixture thereof. 
Preference is given to using aromatic polyamides which form isotropic 
solutions in polar aprotic organic solvents and which contain at least 
two, in particular three, different structural repeat units which differ 
in the diamine units. 
Preferably the aramid is a polymer with the structural repeat units of the 
formulae III, IV and optionally V 
EQU --OC--Ar.sup.1 --CO--NH--Ar.sup.2 --NH-- (III), 
EQU --OC--Ar.sup.1 --CO--NH--Ar.sup.3 --NH-- (IV), 
EQU --OC--Ar.sup.1 --CO--NH--Ar.sup.4 --N--H-- (V), 
where Ar.sup.1, Ar.sup.2, Ar.sup.3 and Ar.sup.4 are each independently of 
the others a bivalent monocyclic or polycyclic aromatic radical whose free 
valences are disposed para or meta or comparably parallel, coaxial or 
angled to each other, and Ar.sup.2, Ar.sup.3 and, if present, Ar.sup.4 
each have different individual meanings within the scope of the given 
definitions, and the respective monomer components underlying the polymer 
are selected so as to produce an aromatic polyamide which forms isotropic 
solutions in organic solvents. 
Any bivalent aromatic radicals whose valence bonds are disposed para or 
comparably coaxial or parallel to each other are monocyclic or polycyclic 
aromatic hydrocarbon radicals or heterocyclic aromatic radicals which can 
be monocyclic or polycyclic. Heterocyclic aromatic radicals have in 
particular one or two oxygen, nitrogen or sulfur atoms in the aromatic 
nucleus. 
Polycyclic aromatic radicals can be fused to one another or be bonded 
linearly to one another via C--C bonds or via --CO--NH-- groups. 
The valence bonds in mutually coaxial or parallel disposition point in 
opposite directions. An example of coaxial bonds pointing in opposite 
directions are the biphenyl-4,4'-ylene bonds. An example of parallel bonds 
pointing in opposite directions are the naphthylene-1,5 or -2,6 bonds, 
whereas the naphthylene-1,8 bonds are parallel but point in the same 
direction. 
Examples of preferred bivalent aromatic radicals whose valence bonds are 
disposed para or comparably coaxial or parallel to each other are 
monocyclic aromatic radicals having free valences disposed para to each 
other, especially 1,4-phenylene, or bicyclic fused aromatic radicals 
having parallel bonds pointing in opposite directions, especially 1,4-, 
1,5- and 2,6-naphthylene, or bicyclic aromatic radicals linked by a C--C 
bond and having coaxial bonds pointing in opposite directions, especially 
4,4'-biphenylylene. 
Any bivalent aromatic radicals whose valence bonds are disposed meta or 
comparably angled to each other are monocyclic or polycyclic aromatic 
hydrocarbon radicals or heterocyclic aromatic radicals which can be 
monocyclic or polycyclic. Heterocyclic aromatic radicals have in 
particular one or two oxygen, nitrogen or sulfur atoms in the aromatic 
nucleus. 
Polycyclic aromatic radicals can be fused to one another or be bonded to 
one another via C--C bonds or via bridging groups such as --O--, 
--CH.sub.2 --, --S--, --CO-- or --SO.sub.2 --. 
Examples of preferred bivalent aromatic radicals whose valence bonds are 
disposed meta or comparably angled to each other are monocyclic aromatic 
radicals having free valences disposed meta to each other, especially 
1,3-phenylene, or bicyclic fused aromatic radicals having mutually angled 
bonds, especially 1,6- and 2,7-naphthylene, or bicyclic aromatic radicals 
linked via a C--C bond but having mutually angled bonds, especially 
3,4'-biphenylylene. 
Minor portions, for example up to 5 mol %, of the monomer units, based on 
the polymer, can be aliphatic or cycloaliphatic in nature, for example 
alkylene or cycloalkylene units. 
Alkylene is to be understood as meaning branched and especially 
straight-chain alkylene, for example alkylene having two to four carbon 
atoms, especially ethylene. 
Cycloalkylene radicals are for example radicals having five to eight carbon 
atoms, especially cycloalkylene. 
All these aliphatic, cycloaliphatic or aromatic radicals can be substituted 
by inert groups. These are substituents which have no adverse effect on 
the contemplated application. 
Examples of such substituents are alkyl, alkoxy or halogen. 
Alkyl is to be understood as meaning branched and especially straight-chain 
alkyl, for example alkyl having one to six carbon atoms, especially 
methyl. 
Alkoxy is to be understood as meaning branched and especially 
straight-chain alkoxy, for example alkoxy having one to six carbon atoms, 
especially methoxy. 
Halogen is for example fluorine, bromine or in particular chlorine. 
Preference is given to aromatic polyamides based on unsubstituted radicals. 
The dicarboxylic acid unit in the aromatic polyamides comprising the 
structural repeat units of the formulae III, IV and optionally V is 
preferably terephthalic acid. 
Examples of preferred diamine combinations from which these preferred 
structural repeat units of the formulae III, IV and V are derived are 
1,4-phenylenediamine, 4,4'-diaminodiphenylmethane and 3,3'-dichloro-, 
3,3'-dimethyl- or 3,3'-dimethoxybenzidine; also 1,4-phenylenediamine, 
1,4-bis(aminophenoxy)benzene and 3,3'-dichloro-, 3,3'-dimethyl- or 
3,3'-dimethoxybenzidine; and also 1,4-phenylenediamine, 
3,4'-diaminodiphenyl ether and 3,3'-dichloro-, 3,3'-dimethyl- or 
3,3'-dimethoxybenzidine; and also 1,4-phenylenediamine, 
3,4'-diaminodiphenyl ether and 4,4'-diaminobenzanilide; and also 
1,4-phenylenediamine, 1,4-bis(aminophenoxy)benzene and 
3,4'-diaminodiphenyl ether. 
Aramids which are derived from such diamine combinations and which are 
preferably for use according to the present invention are described in 
EP-A-199,090, EP-A-364,891, EP-A-364,892, EP-A-364,893 and EP-A-424,860. 
The aromatic polyamides to be used according to the present invention are 
known per se and can be prepared by methods known per se. 
Of these preferred aramids, particular preference is given particularly to 
those where Ar.sup.1 is a bivalent monocyclic or polycyclic aromatic 
radical whose free valences are disposed para or comparably parallel or 
coaxial to each other, 
Ar.sup.2 is a bivalent monocyclic or polycyclic aromatic radical whose free 
valences are disposed para or comparably parallel or coaxial to each 
other, 
Ar.sup.3 is a radical of the formula VI 
EQU --Ar.sup.5 --X--Ar.sup.6 -- (VI), 
where Ar.sup.5 and Ar.sup.6 are independently of each other a bivalent 
monocyclic or polycyclic aromatic radical whose free valences are disposed 
para or comparably parallel or coaxial to each other or where Ar.sup.6 
additionally is a bivalent monocyclic or polycyclic aromatic radical whose 
free valences are disposed meta or comparably angled to each other, 
X is a group of the formula --O--, --S--, --SO.sub.2 --, 
--O----phenylene--O-- or alkylene, and where 
Ar.sup.4 has one of the meanings defined for Ar.sup.2 or Ar.sup.3 but 
differs from the particular Ar.sup.2 or Ar.sup.3 of a molecule. 
Very particular preference is given to aramids where Ar.sup.1 is 
1,4-phenylene, Ar.sup.2 is 1,4-phenylene or a bivalent radical of 
4,4'-diaminobenzanilide, Ar.sup.5 and Ar.sup.6 are each 1,4-phenylene, X 
is --O--, --CH.sub.2 -- or --O--1,4-phenylene--O--, and Ar.sup.4 is a 
bivalent radical of 3,4'-diaminodiphenyl ether, of 3,3'-dichlorobenzidine, 
of 3,3'-dimethylbenzidine or of 3,3'-dimethoxybenzidine. 
The term "fiber" is to be understood in the context of this invention in 
its widest sense; fiber as used herein thus includes for example endless, 
continuous filament fibers, such as mono- or multifilaments, or staple 
fibers, or pulp. 
The production of the aramid fibers to be used according to the present 
invention can be effected by processes known per se, as described for 
example in EP-A-199,090, EP-A-364,891, EP-A-364,892, EP-A-364,893 and 
EP-A-424,860. 
The spin finish can be applied directly after the spinning of the filaments 
or in the aftertreatment. 
Application can be by means of known apparatus, such as dipping, roller 
lick or spraying. 
The aramid fibers treated according to the present invention can have been 
treated with an organic or inorganic drawing finish. 
The aramid fibers of the present invention are notable for excellent 
mechanical properties, such as high breaking strength and initial moduli 
and low breaking extensions, and also for the abovementioned favorable 
application and further processing properties. 
The fibers of the present invention preferably have filament linear 
densities of not less than 1.0 dtex, in particular from 1 to 20 dtex. 
The tenacity of the fibers of the present invention is preferably from 140 
to 290 cN/tex. 
The initial modulus, based on 100% extension, of the fibers of the present 
invention is preferably from 40 to 130 N/rex. 
The cross section of the individual filaments of the fibers of the present 
invention can be optional, for example triangular, tri- or multilobal or 
in particular elliptical or round. 
The fibers of the present invention, which have excellent mechanical and 
thermal properties and are notable for high drawability, can be further 
processed and used in industry in a wide variety of ways. 
The aramid fibers of the present invention, possessing good interfilament 
cohesion and excellent antistatic properties, are used in particular in 
the production of textile sheet materials by intermingling, twisting, 
braiding or folding. The aramid fibers of the present invention are 
preferably used in knitting or weaving. The invention also provides for 
the use for these purposes. 
The aramid fibers of the present invention are processible in particular 
into woven fabrics, knitted fabrics, laid fabrics, braids or webs. 
As mentioned earlier, the spin finished aramid fibers of the present 
invention are notable for a whole series of advantageous properties. 
Trials have shown that the temperature volatility of the spin finishes of 
the present invention within the range from 200.degree. to 220.degree. C. 
was less than 10%, whereas conventional spinning finishes have temperature 
volatilities of up to 60%. 
Furthermore, the water vapor volatility of the spin finishes of the present 
invention at 102.degree. C. is less than 10%, whereas conventional spin 
finishes have water vapor volatilities of up to 25%. 
Moreover, the filament/metal friction of the spin finishes of the present 
invention is 15-20% lower than the values obtained with conventional 
systems. 
In addition, it was found that the abrasion of the spin finishes of the 
present invention, for example in the course of twisting, was very low and 
the abraded-off material was in the form of a dust, was readily removable 
and did not form a tacky build-up on the deflecting elements. Compared 
with conventional systems, an improvement of about 50% was observed. 
It was additionally found that the interfilament cohesion, or transverse 
cohesion between the filaments, of the spin finished aramid fibers of the 
present invention was about 10% higher than that obtained with 
conventional systems.