Note: Descriptions are shown in the official language in which they were submitted.
~A21 14281
Non-tackv,highly elastic Polyurethane elastomer
monofilaments and multifilaments, process for their
production, their use, and partiallv crosslinked
thermoPlastic Polyurethanes for this Purpose
The present invention relates to non-tacky, highly elastic polyurethane
elastomer monofilaments and multifilaments, abbreviated to PU filaments
below, which are produced by spinning a melt of a partially crosslinked
thermoplastic polyurethane, abbreviated to TPU below, obtainable by reacting
a) at least one organic diisocyanate with
10 b) at least one dihydroxyl compound having a molecular weight of from
500 to 4,000,
c) at least one difunctional hydroxyl-containing chain extender having a
molecular weight of from 62 to 380, and
d) at least one at least trifunctional hydroxyl-containing crosslinking agent,
to a process for their production by melt spinning, to their use for the
production of fibers and textile sheet-like structures, and to the partially
crosslinked, thermoplastic polyurethanes which can be used for this purpose.
It is known to produce PU filaments from PU elastomers based on
organic diisocyanates, high-molecular-weight dihyroxyl compounds and low-
molecular-weight chain extenders, for example alkanediols and/or diamines.
The elastomeric behavior of these polyurethanes is based on the entropy
elasticity caused by the segment or block structure, ie by a certain arrangementof the hard and soft phases. The elastomeric behavior is affected by the
starting materials used, the synthetic method, the spinning process and the
aftertreatment.
Since urea structures formed from diamines do not melt without
decomposing, spinning of these PU elastomers by melt spinning, which is
economical and environmentally
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friendly, is impossible. The filament formation takes place, for example in the
case of wet spinning, by coagulation of the dissolved polyurethane in non-
dissolving, usually aqueous precipitation baths and in the case of reactive
spinning, by carrying out the chain extension of an NCO prepolymer with a
diamine and the filament formation simultaneously in the spinning bath.
Although PU elastomers containing no urea structures and based on relatively
high- and low-molecular-weight dihydroxyl compounds can be melt-spun, they
have, however, inadequate heat distortion resistance, which has a
disadvantageous effect on the spinning, for example due to their high tack, and
on textile processing, for example thermofixing, dyeing, washing and ironing.
Melt extrusion, the most economical spinning technique, is therefore unsuitable
for TPUs (Kunststoff-Handbuch, Volume 7, Polyurethane, 2nd Edition, 1983,
pages 611 to 627, edited by Dr. G. Oertel, Carl Hanser-Verlag, Munich,
Vienna) .
In order to prevent tackiness, a special quenching process for the spun
filaments, the use of abhesives and the use of tris(2-hydroxyethyl) isocyanurateduring spinning have, for example, been proposed. However, these measures
have also been unable to solve the problem satisfactorily.
According to DE-A-22 04 470 (CA-A-999,394), polyimide groups have
been incorporated into the polyurethane chain or polyimides have subsequently
been introduced into the polyurethane melt in order to reduce the tack of
extruded continuous PU filaments. However, the PU filaments produced using
the resultant polyurethane compositions must be wound up very slowly and
stretched in a second operation, which means that the productivity is
unsatisfactory and the process is uneconomic. A further disadvantage is that
the addition of additives reduces the molecular weight of the polymer, and thus
reduces the melt viscosity, which in turn has an
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adverse effect on the elastic properties, the elongation at break and the
strength of the resultant yarn.
DE-A-19 44 507 (GB-A-1,245,311) discloses a multistep process which
reduces the tack of PU filaments during melt spinning. The first step involves
5 melt extrusion and solidification of the resultant filaments by quenching, andin the second step the filaments are drawn by at least 30 % and, in a further
step, relaxed by at least 50 % before winding up. The process sequence
suggests that the PU filaments are already in finished, fully cooled form on thetake-off godet. These filaments display the typical properties of a PU
10 elastomer, ie they can no longer be drawn in the true sense, but, due to their
high elasticity, can be stretched greatly, but reversibly.
According to W0 88/04703, the tack of PU filaments to one another and
of the fibrils to one another can be prevented and a high-modulus filament with
better processing properties produced if the polyurethane and the stretching
15 conditions are selected so that irreversible stretching takes place, the relaxation
is omitted, and the take-off rate is additionally increased. This process can beused to TPUs having a softening point of from 180 to 230C, a Shere A
hardness of from 80 to 95 and a density of from 1.1 to 1.25 g/cm2; the
hardness of the TPU is particularly important for the tack of the PU filament.
20 This method has the disadvantage of low elasticity of the resultant PU filament
and the complex spinning process.
According to DE-A-3 911 725, non-tacky PU filaments which can be
produced by melt spinning can be obtained from plasticiser-containing TPU.
The only disadvantage of these PU filaments, which have high tear strength,
25 low plastic deformation and high elastic recovery, is their tendancy to exudethe plasticiser under certain reaction conditions during further processing.
CA 2 1 1 428 1
Thermoplastic PU elastomers which can be converted into elastomer
fibers by, inter alia, melt spinning can furthermore, according to
DE-A-32 33 384 (US-A-4,442,281), be prepared by the polyaddition of
essentially pure transcyclohexane 1,4-diisocyanate, diols having a molecular
weight of from 800 to 4,000 and bisethoxylated bisphenol A, or mixtures of
bisethoxylated bisphenol A and other short-chained diols as chain extenders.
This TPU has the disadvantages of relatively difficult and therefore expensive
preparation of the starting component trans-cyclohexane 1 ,4-diisocyanate and
the relatively low heat distortion resistance of the TPU, which makes textile
aftertreatments of the fibers, for example dyeing, thermofixing, inter alia, at
elevated temperature more difficult or even impossible.
It is an object of the present invention to overcome all or at least some
of the abovementioned disadvantages and to provide a simplified, improved
process for the production of non-tacky,highly elastic PU monofilaments and
multifilaments by melt spinning of TPU. A TPU which can be used for this
purpose should have high heat distortion resistance and high hydrolysis
resistance, should be melt-spinnable, and should be based on industrially readily
accessible and therefore inexpensive starting materials. The filaments produced
from this TPU should be non-tacky and highly elastic and should be
distinguished by good textile processing properties.
We have found that, surprisingly, this object is achieved by using a
specific partially crosslinked TPU.
The present invention accordingly provides non-tacky, highly elastic
polyurethane elastomer monofilaments and multifilaments, produced by
spinning a melt of a partially crosslinked TPU obtainable by reacting
a) at least one organic, preferably aromatic, diisocyanate with
b) at least one dihydroxyl compound having a molecular weight of from
500 to 4,000.
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c) at least one difunctional hydroxyl-containing chain extender having
a molecular weight of from 62 to 380, and
d) at least one at least trifunctional hydroxyl-containing crosslinking
agent.
The present invention furthermore provides a process for the
production of non-tacky, highly elastic PU monofilaments and multifilaments by
melt-spinning the partially crosslinked TPU as claimed in claim 11, the partially
crosslinked TPUs, which are preferably prepared by the one-shot process, as
claimed in claim 15, and the use of non-tacky, highly elastic PU monofilaments and
multifilaments according to the invention for the production of textile fibers, textile
sheet-like structures and industrial fibers as claimed in claim 14.
The addition of at least trif unctional, preferably trif unctional hydroxyl-
containing crosslinking agents allows the heat distortion resistance of the TPU to
be increased without any adverse effect on the spinning properties of the TPU
melt. The use of, preferably, polyoxyalkylene glycols and polyether polycarbonate
diols asthe relatively high-molecular-weight dihydroxyl compound(s) (b) guarantees
high hydrolysis resistance of the PU filaments. It was furthermore surprising that
the PU filaments produced can be wound up without sticking, are highly elastic
and have good textile processing properties.
The following details apply to the preparation of the TPUs which can
be used according to the invention, to the starting components therefor, and to the
production of the non-tacky, highly elastic PU monofilaments and multifilaments:a) The organic diisocyanates (a) used are, for example, aliphatic, cycloaliphatic
and preferably aromatic diisocyanates. Specific examples which may be
mentioned are: aliphatic diisocyanates having up to a maximum of 12
carbon atoms in the alkylene radical,
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for example hexamethylene diisocyanate, cycloaliphatic diisocyanates, for
example isophorone diisocyanate, 1-methyl-2,4- and 2,6-cyclohexane
diisocyanate and the corresponding isomer mixtures, 4,4'-, 2,4'- and 2,2'-
dicyclohexylmethane diisocyanate and the corresponding isomer mixtures,
and preferably aromatic diisocyanates, for example 2,4-tolylene
diisocyanate, mixtures of 2,4- and 2,6- tolylene diisocyanate, 4,4'-, 2,4'-
and 2,2'- diphenylmethane diisocyanate, mixtures of 2,4'- and 4,4'-
diphenylmethane diisocyanate and 4,4'-diisocyanate-1,2-diphenylethane.
Preference is given to 1,6-hexamethylene diisocyanate, isophorone
diisocyanate, diphenylmethane diisocyanate isomer mixtures having a 4,4'-
diphenylmethane diisocyanate content of greater than 96 % by weight, and
in particular 4,4'-diphenylmethane diisocyanate.
b) The dihydroxyl compounds (b) having a molecular weight of from 500 to
4,000, preferably from 600 to 3,000, in particular from 800 to 2,200, are
preferably polyether polycarbonate diols and polyoxyalkylene glycols,
expediently those selected from the group consisting of polyoxybutylene
glycols, polyoxybutylene-polyoxyethylene glycols, polyoxybutylene-
polyoxypropylene glycols and polyoxybutylene-polyoxypropylene-
polyoxyethylene glycols. Particular preference is given to polyoxybutylene
glycols. Suitable polyether polycarbonate diols are described, for example,
in US-A-5,137,935 (DE-A-40 04 882), which is incorporated into this
patent description by way of reference. Preferred polyether polycarbonate
diols are polyoxybutylene polycarbonate diols. However, other suitable
dihydroxyl compounds are hydroxyl-containing polymers, for example
polyacetals, such as polyoxymethylenes, and in particular water-insoluble
formals, for example polybutanediol formal and polyhexanediol
~A21 14281
formal, and polycarbonates, in particular those made from diphenyl
carbonate and 1,6-hexanediol or 1,4-butanediol, or mixtures thereof,
prepared by esterification. The dihydroxyl compounds mentioned by way
of example can be used as individual components or in the form of mixtures
of at least two dihydroxyl compounds.
c) The difunctional hydroxyl-containing chain extenders having a molecular
weight from 62 to 380, preferably from 62 to 210, are preferably
alkanediols having 2 to 12 carbon atoms, preferably 4 and/or 6 carbon
atoms, for example ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-
1 0 pentanediol, 1 ,6-hexanediol, 1 ,7-heptanediol, 1 ,8-octanediol, 1 ,10-
decanediol and 1,1 2-dodecanediol, and dialkylene glycols, for example
diethylene glycol, dipropylene glycol and dibutylene glycol.
However, other suitable chain extenders are, for example, diesters of
terephthalic acid with glycols having 2 to 4 carbon atoms, for example bisethylene
1 5 glycol terephthalate or bis- 1 ,4-buta nediol terephthalate, and hydroxyal kylene ethers
of hydroquinone, for example 1,4-i(,B-hydroxyethyl)hydroquinone.
Chain extenders which have proven highly successful and are
therefore preferred are 1,6-hexanediol and in particular 1 ,4-butanediol, or mixtures
of 1,6-hexanediol and 1,4-butanediol.
d) The essential prerequisite for the preparation of the partially crosslinkedTPUs which can be used according to the invention is the use of at least
one, at least trifunctional, preferably trifunctional to octafunctional, in
particular trifunctional, hydroxyl-containing crosslinking agent (d).
Crosslinking agents of this type advantageously have a molecular weight of
from 90 to 400, preferably from 90 to 138. Specific examples of suitable
crosslinking agents are: glycerol, trimethylolpropane,
~A2 I 1 4281
glycerol which has been alkoxylated with up to 3 mol of alkylene oxide, for
example ethylene oxide, and/or trimethylopropane, pentaerythritol, sorbitol
and sucrose, particular preference being given to glycerol or
trimethylolpropane or mixtures of glycerol and trimethylolpropane.
In order to adjust the hardness of melting point of the TPU, the
starting components (b) to (d) can be varied in relatively broad molar ratios.
Success has been achieved, for example, using molar dihydroxyl compound (b):
chain extender (c) ratios of from 1:0.5 to 1:20, preferably from 1:1 to 1:10, inparticular from 1:1 to 1:5, and addition of crosslinking agent (d) in an amount of
from 0.01 to 10 mol %, preferably from 0.2 to 5 mol %, in particular from 0.3 to3.5 mol %, based on the molecular weight of the dihydroxyl compounds (b).
In order to prepare the TPUs which can be used according to the
invention, the starting components (a) to (d) are advantageously reacted in suchamounts that the ratio between the number of equivalents of NC0 groups of the
diisocyanates (a) and the total number of hydroxyl compounds (b) to (d) is from
0.9 to 1.1:1, preferably from 0.95 to 1.05:1, in particular from 0.98 to 1.03:1.The polyhydroxyl compounds (b) to (d) are advantageously reacted with the
diisocyanate in the form of a mixture.
a) The TPUs which can be used according to the invention are preferably
prepared in the absence of catalysts (a). However, it may be expedient,
depending on the type of starting components (a) to (d) used and in
particular on their reactivity, to accelerate the reaction between the NC0
groups of the diisocyanate (a) and the hydroxyl groups of the starting
components (b) to (d) by using catalysts. Examples of suitable catalysts are
the tertiary amines known from the prior art, for example triethylamine, N,N-
dimethylcyclohexylamine, N-methylmorpholine, N,N'-dimethyl- and -
diethylpiperizine,
(~A21 14281
tris (dimethylaminoethyl)-(s)-triazine, pentamethyl-diethylenetriamine,
N,N,N',N'-tetramethylbutylenediamine, N,N,N',N'-tetramethyl-4,4'-
diaminodicyclohexylmethane, 2-(dimethylaminoethoxy)ethanol and
diazabicyclo[2. 2. 2.]octane, and in particular organo-metallic compounds, for
example titanic esters, iron compounds, tin compounds, for example tin
diacetate, tin dioctanoate, tin dilaurate or the dialkyltin salts of aliphatic
carboxylic acid, for example dibutyltin diacetate, and dibutyltin dilaurate,
and mixtures of tertiary amines and organometallic compounds. The
catalysts are usually employed in amounts of from 0.001 to 0.1 parts by
weight per 100 parts by weight of the polyhydroxyl compounds (b) to (d).
f) In addition to catalysts, auxiliaries and/or additives (f) can, if desired, be
incorporated into the starting components. Examples which may be
mentioned are lubricants, inhibitors, hydrolysis, light, heat and discoloration
stabilizers, for example caused by chlorine attack, flameproofing agents,
1 5 dyes and pigments.
Further details on the above auxiliaries and additives (f) are given in
the specialist literature, for example the monograph by J.H. Saunders and K.C.
Frisch, "High Polymers", Volume XVI, Polyurethane, Parts 1 and 2, Interscience
Publishers, 1 962 and 1 964 respectively, and DE-A 29 01 774.
The partially crosslinked TPUs which can be used according to the
invention are preferably prepared by the one-shot process. The TPUs can be
obtained by the extruder or preferably by the belt method by batchwise or
continuous mixing of the starting components (a) to (d) and, if used, (e) and/or (f),
allowing the reaction mixture to react to completion in the extruder or on a support
belt at from 40 to 230C, preferably at 70 to 1 80C, and subsequently
granulating the resultant TPUs.
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- 10 -
In the belt method, which is preferred, the starting components (a)
to (d) and, if used, (e) and/or (f) are mixed continuously at above the melting point
of the starting components (a) to (d) with the aid of a mixer head. The reactionmixture is applied to a support, preferably a conveyor belt, for example made ofmetal, and passed through a temperature-controlled zone with a length of from 1
to 20 meters, preferably from 3 to 10 meters, at a rate of from 1 to 20 m/min,
preferably from 4 to 10 m/min. The reaction temperature in this zone is from 60
to 300C, preferably from 100 to 1 80C. The partially crosslinked TPUs obtainedcan be granulated after cooling and stored if desired.
The non-tacky, highly elastic PU monofilaments and multifilaments
according to the invention can be produced by the melt spinning process, which
is known per se. Particularly suitable for the production, and therefore preferred,
are extruder melt-spinning units, which can optionally, in addition to the air cooling
usually used, for example by means of a cooling air shaft, be fitted with a water-
cooling device for cooling the freshly spun PU filaments.
In a preferred variant of the process for the production of the PU
filaments according to the invention, the TPUs which are suitable according to the
invention are melted in a extruder at from 150 to 250C, preferably at from 170
to 230C, depending on the partially crosslinked TPU employed in each case, the
melt is shaped to give filaments with the aid of a gear spinning pump and a single-
hole or multi-hole spinneret with melt filtration, and the resultant filaments are
cooled by water or air, depending on the take-off rate used, and wound up on
conventional reeling units.
The reeling up of the PU filaments produced according to the
invention is advantageously carried out with additional application of a spin finish
based on, for example, silicone or silicic acid dispersions, which
(~A21 14281
additionally improve the reeling and winding up, which are essentially already tack-
free, of the spinning reel and the further processing of the PU monofilaments and
multifilaments.
Spin finishes of this type of known commercial products. Suitable
spin finishes based on polysiloxane elastomers or mixtures of polysiloxanes and a
silicon compound, for example, are commercially available from BASF
Aktiengesellschaft under the tradenames Siligen SIP, Siligen NSI, and Silign LSI,
and one based on silicates under the tradename Siligen E.
The melt spinning can be carried out using dies of conventional
capillary geometry. However, it is advantageous for melt spinning to use dies
having a special capillary geometry, expediently those having a length of from 1 D
to 5D and a capillary diameter of from 0.05 to 2 mm, capillary diameters of from0.1 to 0.5 mm being particularly preferred in the case of multifilaments and
capillary diameters of from 0.5 to 2 mm being particularly preferred in the case of
monofilaments, since these measures additionally permanently improve the
mechanical properties of the PU filaments according to the invention, and in
particular PU filaments having very good elastic recovery and elongation at break
can be obtained.
The PU filaments according to the invention or produced by the
process according to the invention do not stick to one another, and in the case of
multifilaments the individual capillaries do not stick to one another, and have a high
tear strength with an elongation at break, measured in accordance with DIN 53
815, of greater than 300 %, preferably from 320 to 800 %, and low plastic
deformation and high elastic recovery (measured in accordance with DIN 53 835).
The elongation ratio, defined as the quotient of the elastic elongation EB and the
total elongation EW8~ measured in accordance with DIN 53 835, is greater than 0.8,
preferably from 0.85 to 0.95.
(~A21 14281
- 12-
The textile properties of the PU filaments according to the invention
can, if desired, be further improved with respect to their elastic recovery, tear
strength and elongation at break by thermal aftertreatment, for example by
conditioning at from 50 to 170C, preferably at from 75 to 130C, in air or in awater-vapor atmosphere or, for example, by hot post-drawing, for example at a
filament tension of, expediently, from 0.05 to 0.2 cN/dtex.
The high heat distortion resistance of the TPUs which can be used
according to the invention and the non-tacky winding up and unwinding from the
spinning reel mean that the PU filaments according to the invention can
advantageously be subjected to textile conversion, for example dyeing and
thermof ixing .
The non-tacky, highly elastic PU monofilaments and multifilaments
according to the invention are used for the production of industrial fibers and
textile fibers and sheet-like structures made from industrial fibers and textile fibers.
EXAMPLES
EXAMPLE 1
The TPU preparation is carried out by the one-shot process.
To this end, a mixture of 1,500 9 (1.49 mol) of polyoxybutylene
glycol and 1.25 9 (0.009 mol) of trimethylolpropane was degassed for 1 hour at
110C and 5 mbar. 187.5 9 (2.08 mol) of 1,4-butanediol were stirred into the
mixture, the resultant clear solution was warmed to 70C, and 909.3 9 (3.63 mol)of 4,4'-diphenylmethane diisocyanate at 65C were then added with vigorous
stirring (1,000 revolutions/minute).
When a reaction temperature of 120C had been reached, the
homogeneous reaction mixture was poured onto a hotplate measuring 550 x 380
mm held at 125 C and covered with teflon-treated glass fiber fabric.
After a reaction time of approximately 2 minutes,
CA21 14281
- 13-
the hot TPU obtained was coarsely comminuted and conditioned at 100C for 15
hours in a drying cabinet. After cooling to room temperature, TPU granules having
a particle size in the range from 4 to 6 mm were produced with the aid of a cutting
mill and were stored in the interim or immediately spun by melt spinning.
Production of PU multifilaments
The TPU prepared as described in Example 1 was spun using an
extruder spinning unit which had the following technical data:
Extruder screw diameter: 25 mm,
Extruder screw length: 25 D,
Spinneret: 30 hole/0.3 mm capillary diameter and 0.6 mm capillary length and
Throughput: 1.2 kg/h,
at a melt temperature of 220C and a spinning rate of 450 m/min, with application
of a polysiloxane-based spin finish (Siligen MBI from BASF Aktiengesellschaft) and
with air cooling of the freshly spun PU filaments.
The PU filaments, which can be wound up without sticking, were
subsequently treated for 10 minutes with air at 100C.
The PU filaments obtained in this way had the mechanical properties
shown in Table ll.
EXAMPLES 2 TO 6 AND COMPARATIVE EXAMPLE
The procedure was similar to that of Example 1, but the starting
components and amounts shown in Table I were used, with the abbreviations as
follows:
MDI: 4,4'-diphenylmethane diisocyanate
BuOH: 1,4-butanediol
TMP: Trimethylolpropane
TMP-EO: Product of the reaction of 1 mol of ethylene oxide and
1 mol of TMP (tradename Lupranol 3900, MW:
178246)
PTHF 1000 (1): Polyoxytetramethyleneglycol, molecular weight: 1010
PTHP 1000 (2): Polyoxytetramethyleneglycol, molecular
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weight: 1003
PTHF 1000 (3): Polyoxytetramethylene glycol, molecular weight: 993
PTHF-CD 1 250: Polyoxybutylenepolycarbonate diol, molecular weight:
1 275
PTHF-CD 2000: Polyoxybutylenepolycarbonate diol, molecular weight:
2047
The PU filaments obtained had the mechanical properties shown in
Table ll.
TABLE I
TPU prepared by the one-shot process
Example Diisocyanate Dihydroxyl Compound Chain extender Crosslinking agent
TypeAmount Type Amount TypeAmount TypeAmount
MDI909.3 gPTHF 1000 (1) 1500 9 BuOH187.5 9 TMP1.25 9
(3.63 mol) (1.49 mol) (2.08 mol) (0.009 mol)
2 MDI917.9 9PTHF 1000 (2) 1500 9 BuOH187.5 9Glycerol 2.25 9
(3.67 mol) (1.50 mol) (2.08 mol)(0.024 mol)
3 MDI918.2 9PTHF 1000 (1) 1500 g BuOH187.5 9Glycerol 3.00 g
(3.67 mol) (1.49 mol) (2.08 mol)(0.033 mol)
4 MDI718.9 9PTHF-CD 2000 (1)1500 9 BuOH187.5 g TMP1.50 9
(2.87 mol) (0.73 mol) (2.08 mol) (0.011 mol)
MDI834.4 gPTHF-CD 1250 1500 9 BuOH187.5 9 TMP2.5 9
(3.33 mol) (1.18 mol) (2.08 mol) (0.019 mol)
6 MDI916.4 9PTHF 1000 (3) 1500 9 BuOH187.5 9TMP-H0 2.00 9(3.66 mol) (1.51 mol) (2.08 mol)(0.011 mol)
Comparative MDI905.8 9PTHF 1000 (1) 1500 9 BuOH187.5 9
Example (3.62 mol) (1.49 mol) (2.08 mol)
TABLE ll
Mechanical properties of PU filaments produced by melt spinning of the TPUs fromExamples 1 to 6 and the comparative example
PU Filament Linear Tear strengthElongation at break Elastic recovery Tack
from Example density in accordancein accordance in accordance temperature
with DIN 53with DIN 53 815 with DIN 53 835 [C]
815
600/30 dtex 1.0 cN/dtex 500 % 0.90 170
2 483/30 dtex 0.8 cN/dtex 568 % 0.87 170
3 637/30 dtex 0.75 cN/dtex 338 % 0.84 170
4 492/30 dtex 0.9 cN/dtex 465 % 0.9 170
532/30 dtex 0.9 cN/dtex 465 % 0.89 170 6-
6 557/30 dtex 0.8 cN/dtex 419 % 0.85 165
Comparative 470/30 dtex 0.8 cN/dtex 440 % 0.75 160
Example
Stretching ratio
r~
r~
~o
