U.S. patent application number 10/704862 was filed with the patent office on 2004-05-20 for method for the manufacture of synthetic fibers from a melt mixture based on fiber forming polymers.
This patent application is currently assigned to Zimmer AG. Invention is credited to Janas, Wolfgang, Klein, Alexander, Kretschmann, Bernd, Schwind, Helmut, Ude, Werner.
Application Number | 20040096655 10/704862 |
Document ID | / |
Family ID | 26005624 |
Filed Date | 2004-05-20 |
United States Patent
Application |
20040096655 |
Kind Code |
A1 |
Schwind, Helmut ; et
al. |
May 20, 2004 |
Method for the manufacture of synthetic fibers from a melt mixture
based on fiber forming polymers
Abstract
The present invention relates to a method for the manufacture of
synthetic fibers from a melt mixture of fiber forming matrix
polymers, wherein at least one second amorphous additive polymer,
which is immiscible with the fiber forming matrix polymer, is added
to the fiber forming matrix polymers in a quantity of 0.05-5 wt %
(with reference to the total weight of fiber forming matrix polymer
and the additive copolymer). The additive polymer is obtained by
multiple initiation. Furthermore, the present invention also
relates to the synthetic fibers produced by the method.
Inventors: |
Schwind, Helmut; (Hanau,
DE) ; Ude, Werner; (Darmstadt, DE) ; Janas,
Wolfgang; (Geilseback, DE) ; Klein, Alexander;
(Ingelheim, DE) ; Kretschmann, Bernd; (Alzenan,
DE) |
Correspondence
Address: |
Michael S. Greenfield
McDonnell Boehnen Hulbert & Berghoff
32nd Floor
300 S. Wacker Drive
Chicago
IL
60606
US
|
Assignee: |
Zimmer AG
|
Family ID: |
26005624 |
Appl. No.: |
10/704862 |
Filed: |
November 10, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10704862 |
Nov 10, 2003 |
|
|
|
09852515 |
May 10, 2001 |
|
|
|
6667003 |
|
|
|
|
Current U.S.
Class: |
428/364 |
Current CPC
Class: |
D01D 1/065 20130101;
D01D 5/28 20130101; Y10T 428/2913 20150115; D01F 6/92 20130101 |
Class at
Publication: |
428/364 |
International
Class: |
D02G 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 2000 |
DE |
100 22 889.5 |
Mar 27, 2001 |
DE |
101 15 203.5 |
Claims
We claim:
1. A method of manufacturing synthetic fibers from a melt mixture
of fiber forming matrix polymers, the method comprising adding to
the fiber forming matrix polymers 0.05-5 wt % of at least one
amorphous additive polymer that is immiscible with the fiber
forming matrix polymer, wherein the additive polymer is obtained by
multiple initiation and the wt % is with reference to the total
weight of fiber forming matrix polymer and the additive
copolymer.
2. The method according to claim 1, wherein the additive polymer is
obtained by radical initiated polymerization in the presence of a
mixture comprising at least two initiators with differential half
lives.
3. The method according to claim 1, wherein the additive polymer
has a residual monomer content of less than 0.62 wt % with
reference to the total weight of the additive polymer.
4. The method according to claim 1, wherein the additive polymer
has a residual monomer content of less than 0.47 wt % with
reference to the total weight of the additive polymer.
5. Method according to claim 1, wherein the fiber forming matrix
polymer is one or more polyesters.
6. The method according to claim 5, wherein the fiber forming
matrix polymer is polyethylene terephthalate (PET),
polytrimethylene terephthalate (PTMT) and/or polybutylene
terephthalate (PBT).
7. The method according to claim 1, wherein the additive polymer is
one or more polymers obtained by the polymerization of monomers
having the general formula I 4and wherein R.sup.1 and R.sup.2 are
independently a substituent that consists of the optional atom C,
H, O, S, P and halogen atom, where the total of the molecular
weights of R.sup.1 and R.sup.2 is at least 40 dalton.
8. The method according to claim 7, wherein the additive polymer is
polymethyl methacrylate and/or polystyrene.
9. The method according to claim 1, wherein the additive polymer is
one or more polymers obtained by the copolymerization of 30-99 wt %
E, 0-50 wt % F, 0-50 wt % G, and 0-50 wt % H, wherein E=monomers
chosen from the group consisting of acrylic acid, methacrylic acid
and CH.sub.2.dbd.CR--COOR', where R is --H atom or --CH.sub.3, and
R' is C.sub.1-15 alkyl, C.sub.5-12 cycloalkyl, or C.sub.6-14 aryl,
F=monomers chosen from the group consisting of styrene and
C.sub.1-3 alkyl substituted styrenes, G=monomers, chosen from the
group of compounds consisting of compounds having formula II, III
and IV: 5where R.sup.3, R.sup.4, and R.sup.5 are independently --H,
C.sub.1-15 alkyl, C.sub.5-12 cycloalkyl, or C.sub.6-14 aryl, and
H=one or more ethylenically unsaturated monomers optionally
copolymerized with E, F, and/or G and selected from the group
consisting of .alpha.-methylstyrene, vinyl acetate, acrylic acid
esters and methacrylic acid esters differing from E, acrylonitrile,
acrylamide, methacrylamide, vinyl chloride, vinylidene chloride,
halogen substituted styrenes, vinyl ethers, isopropylene ethers,
and dienes, where the total of E, F, G and H is 100% of the
polymerizable monomers.
10. The method according to claim 9 wherein the additive polymer is
a terpolymer of methyl methacrylate, styrene, and
N-cyclohexylmaleinimide.
11. A synthetic fiber obtained by the method according to one of
claims 1-10.
12. The method according to claim 1, further comprising stretch
processing or stretch texturing processing of the synthetic
fibers.
13. A staple fiber obtained by the method according to one of
claims 1-10.
14. An industrial filament obtained by the method according to one
of claims 1-10.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for the
manufacture of synthetic filaments from a mixture of fiber forming
polymers. The filaments can be used as endless filaments or they
can be further processed to staple fibers.
[0003] 2. Summary of the Related Art
[0004] Spinning of polymer mixtures to form synthetic filaments is
known. The purpose of using an additive polymer to form a mixture
is to achieve, at a given spinning speed, a higher elongation at
break of the spun filament. This permits a higher stretch ratio for
the manufacture of the final yarn, which, in turn, results in a
higher productivity of the spinning unit.
[0005] Increased production leads to improved profitability for the
manufacturing process. Productivity is reduced to a certain extent
by production difficulties and more expensive high-speed
installations. The additional costs for the additive polymer can be
considerable so, depending on the quantity added, zero
profitability can result. The market availability of the additive
polymer also plays an important role. Many of the additives
described in the literature are commercially unfeasible for
large-scale industrial conversion.
[0006] Producers or process operators must take into account the
entire production chain and cannot limit themselves to increasing
the production of a single step (for example, the spinning
process), only. The subsequent processes must not be negatively
impacted. In particular it is a main objective of the present
invention not to negatively impact the subsequent processes,
preferably to improve said subsequent processes despite of an
increased spinning speed.
[0007] In the manufacture of POYs (partially oriented yarns), very
high elongations at break for polymer mixtures has been achieved
(even at high spinning speeds) and is characterized by a strong
reduction in the degree of orientation. Such spun filaments are
known to be unstable during storage and cannot be applied and
processed in stretch texturing at high speeds. Elongations at break
of <70% (indicated for high spinning speeds) in turn means a
considerable degree of crystallization, which reduces the strength
that can be achieved in the texturing process.
[0008] The first proposed solutions for these problems were
disclosed in the Patents EP 0 047 644 B (Teijin), DE 197 07 447
(Zimmer), DB 199 37 727 (Zimmer), DB 199 37 728 (Zimmer) and WO
99/07 927 (Degussa). EP 0 047 464 B concerns an unstretched polymer
yarn, where, as a result of the addition of 0.2-10 wt % of a
polymer of the type --(--CH.sub.2--CR.sup.1R- .sup.2--).sub.n--
(e.g., poly(4-methyl-1-pentene) or polymethyl methacrylate),
improved productivity and higher stretch ratios are achieved as a
result of the increase in the elongation at break of the spun
filament at speeds of 2500-8000 m/min. It is necessary to achieve a
fine and homogeneous dispersion of the additive polymer by mixing,
where a particle diameter .ltoreq.1 .mu.m avoids fibril formation.
The effect arises from the combined action of three
properties--chemical additive structure, which allows almost no
elongation of the additive molecule, low mobility, and the
compatibility between polyester and additive. These factors serve
to increase productivity. No requirements for the stretch texturing
are disclosed. Carrying out the method disclosed in WO 99/07927
leads to a high consumption of additive polymer and an impairment
of the quality and the subsequent processability of the resulting
fibers.
[0009] DB 197 07 447 (Zimmer) concerns the manufacture of polyester
or polyamide filaments with an elongation at break of .ltoreq.180%.
The addition of 0.05-5 wt % of a copolymer made of 0-90 wt %
(meth)acrylic acid alkyl ester, 0-40 wt % maleic acid (anhydride),
and 5-85 wt % styrene to the polyester or polyamide allows a clear
increase in the spinning draw-off speed.
[0010] Patent DE 199 37 727 (Zimmer) discloses the manufacture of
polyester staple fibers from a polymer mixture, which mixture
contains 0.1-2.0 wt % of an immiscible, amorphous, additive polymer
having a glass transition temperature of 90-170.degree. C. The
ratio of the additive polymer melt viscosity to the melt viscosity
of the polyester component is indicated to be from 1:1 to 10:1.
[0011] DE 199 37 728 (Zimmer) relates to a method for the
manufacture of HMLS fibers made of polyester, additive polymer, and
optionally additives with a spinning draw-off speed of 2500-4000
m/min. The additive polymer is reported to have a glass transition
temperature of 90-170.degree. C., and the ratio of the melt
viscosity of the additive polymer to the melt viscosity of the
polyester component is reported to be from 1:1 to 7:1.
[0012] WO 99/07927 relates to the manufacture of POYs by spinning
polymer mixtures based on polyester at a draw-off speed v of at
least 2500 m/min, where a second, amorphous, thermoplastically
processible copolymer is added to the polyester and has a glass
transition temperature of more than 100.degree. C. The ratio of the
melt viscosity of the copolymer to the melt viscosity of the
polyester is reported to be from 1:1 to 10:1. At least 0.05 wt % of
copolymer is added to the polyester, and the quantity M of the
copolymer added to the polyester is dependent on the draw-off speed
v and is 1 M = [ 1 1600 v ( m min ) - 0.8 ] [ w t % ]
[0013] Although the foregoing methods result in very good filament
rupture rates that are suitable for practical use, industrial use
nevertheless requires methods for spinning polymer mixtures with
even lower number of filament ruptures to further increase the
efficiency of the spinning method. Furthermore, the behavior of the
synthetic filaments during subsequent processing, particularly
during stretch texturing, should be improved.
[0014] In the foregoing methods, the additive polymer agents for
increasing elongation are usually granulated in order to increase
their flowability before addition by metering to the polyester.
However, due to large particle size, the granulated additive
polymer is relatively difficult to add, and the metering is not
consistent. This leads to a worsening of the yarn characteristics,
e.g., dye uptake behavior and particularly the homogeneity of the
synthetic fibers.
SUMMARY OF THE INVENTION
[0015] We recognized that granulating the elongation increasing
agent is time and cost intensive, and, therefore, methods for the
melt spinning of polymer mixtures using non-granulated elongation
increasing agents would be desirable. We report here that the
elongation increasing agents can be added evenly and continuously
by metering without granulating. As described below, this is
accomplished according to the present invention by employing
amorphous additive polymers obtained by multiple initiation. We
have unexpectedly found that use of such amorphous additive
polymers significantly lessens the residual monomer content of the
synthetic fibers produced, thereby obviating the need to granulate
the additive polymers as practiced in the art.
[0016] The present invention comprises a simple method for the
manufacture of synthetic filaments from a mixture of fiber forming
matrix polymers that allows the manufacture of synthetic fibers
with a lower fiber rupture rate. In particular, the method of
manufacture yields POYs having values of elongation at break of
90-165%, high consistency with regard to the filament
characteristics, and a low degree of crystallinity.
[0017] The present invention also comprises a method for the
manufacture of synthetic fibers from a mixture of fiber forming
matrix polymers that allows the use of non-granulated elongation
increasing agents and thus is considerably more cost effective than
methods known in the state of the art.
[0018] The present invention also comprises a method for spinning
synthetic filaments that can be carried out on a large industrial
scale in a cost effective manner. In particular, the method of the
invention allows the manufacture of POYs with very high draw-off
speeds, preferably .gtoreq.2500 m/min.
[0019] The method of the invention does not negatively impact
subsequent processing; rather it improves it despite the increased
spinning speed.
[0020] According to the invention, the synthetic fibers lend
themselves to further processing in a simple manner. In particular,
the POYs obtained according to the invention allow further
processing in a stretching process or a stretch texturing process,
preferably at high processing speeds and with a small number of
filament ruptures.
[0021] The present method comprises the manufacture of synthetic
fibers from a melt mixture of fiber forming matrix polymers,
wherein one adds to the fiber forming polymer matrix 0.05-5 wt %
(with reference to the total weight of the fiber forming matrix
polymer) at least one second amorphous additive polymer that is
immiscible with the fiber forming matrix polymer and that is
synthesized by multiple initiation. This method unexpectedly yields
synthetic fibers with a low filament rupture rate. Furthermore, the
method according to the invention does not require granulation of
the additive polymer elongation increasing agent.
[0022] At the same time, the method according to the invention
permits formation of a good spool arrangement in a simple manner
that allows homogeneous and nearly error free dying and further
processing of the synthetic fiber due to the high homogeneity of
the synthetic fiber produced by the method. The synthetic fibers
produced by the method of the invention can be further processed in
a simple manner, on a large industrial scale, and cost effectively.
For example, the POYs according to the invention can be stretched
or stretch textured at high speeds with a small number of filament
ruptures. The method according to the invention is particularly
well suited for the manufacture of POYs having elongation at break
values of 90-165%, a high homogeneity with respect to the filament
characteristics, as well as a low degree of crystallization.
DETAILED DESCRIPTION OF THE INVENTION
[0023] The method of the present invention concerns the manufacture
of synthetic fibers from a melt mixture of fiber forming matrix
polymers.
[0024] Spinning according to the invention can occur by means of a
direct spinning method, in which the elongation increasing agent is
added as a melt by metering to the melt of the matrix polymers, or
by an extrusion spinning method, in which the elongation increasing
agent is added as a solid substance to the matrix polymer and
melted thereafter. Additional details concerning suitable spinning
methods can be obtained from the literature, for example, from the
Patents EP 0 04747 464 B, WO 99/07 927, DE 100 22 889 and DE 100 49
617, whose disclosures are incorporated by reference.
[0025] In the context of the present invention, synthetic fibers
denote all types of fibers that can be obtained by spinning
mixtures of synthetic, thermoplastic polymers. They include, among
other fibers, staple fibers (spinning fibers) and textile
filaments, such as smooth yarns, POYs, FOYs, and industrial
filaments.
[0026] Further details concerning synthetic fibers, particularly
with reference to their material properties and the usual
manufacturing conditions, can be obtained from the literature, for
example, from Fourn "Synthetische Fasern: Herstellung, Maschinen
und Apparate, Eigenschaften; Handbuch fur Anlagenplanung,
Maschinenkonstruktion und Betrieb [Synthetic Fibers: Manufacture,
Machines and Apparatuses, Properties; Handbook for Installation
Planning, Machine Construction and Operation]," Munich, Vienna;
Hanser Verlag 1995, as well as from the Patents DE 199 37 727
(staple fibers), DE 199 37 728 and DE 199 37 729 (industrial yarns)
and WO 99/07 927 (POYs). The disclosures of these publications is
incorporated by reference.
[0027] The method is well suited for the manufacture of staple
fibers, smooth fibers, POYs, FOYs or industrial filament. We have
found the method to be particularly well suited for the manufacture
of POYs.
[0028] According to the invention, it is possible to use
thermoplastically processible polymers, preferably polyamides, such
as polyamide-6 and polyamide-6,6, and polyester as the fiber
forming matrix polymers. It is also possible to use mixtures of
different polymers. Preferably, the polymers manufactured according
to the method of the invention are polyesters, particularly
polyethylene terephthalate (PET), polyethylene naphthalate,
polytrimethylene terephthalate (PTMT) and polybutyelene
terephthalate (PBT). In a particularly preferred embodiment of the
present invention, the matrix polymer is polyethylene
terephthalate, polytrimethylene terephthalate or polybutylene
terephthalate (most preferably polyethylene terephthalate).
[0029] Preferably, the method of the invention employs homopolymers
as the fiber forming matrix polymers. However, copolymers can also
be used, preferably polyester copolymers containing up to 15 mol %
of conventional co-monomers, such as, for example, diethylene
glycol, triethylene glycol, 1,4-cyclohexane dimethanol,
polyethylene glycol, isophthalic acid and/or adipic acid.
[0030] The polymers according to the invention can contain as
additional components additives that are conventionally used for
thermoplastic mold compositions and that contribute to improving
the polymer properties. Examples of such additives are:
antistatics, antioxidants, fire inhibitors, lubricants, dyes, light
stabilizers, polymerization catalysts and polymerization promoting
agents, adhesives, matting agents and/or organic phosphites. These
additives can be used in the usual quantity employed fiber
manufacturing, preferably in quantities of up to 10 wt %,
advantageously <l wt %, with reference to 100 wt % of the
polymer mixture.
[0031] If a polyester is used in the method according to the
invention, it can also contain a small proportion (maximum 0.5 wt
%) of branching components, e.g., polyfunctional acids such as
trimellitic acid, pyromellitic acid, or tri- to hexa-valent
alcohols, such as trimethylolpropane, pentaerythritol,
dipentaerythritol, glycerol, or corresponding hydroxy acids.
[0032] According to the invention, one adds to the matrix polymer
an additive polymer in a quantity of at least 0.05 wt %, where the
additive polymer is amorphous and largely insoluble in the matrix
polymer. Essentially the two polymers must be immiscible, and they
must form two phases that can be distinguished microscopically.
Furthermore, the additive polymer must have a glass transition
temperature of more than 100.degree. C. (determinable by DSC using
a heating rate of 10.degree. C./min) and must be thermoplastically
processible. The melt viscosity of the additive polymer should be
such that the ratio of its melt viscosity to that of the matrix
polymer is equal to or greater than 1, preferably between 1:1 and
10:1, more preferably between 1.4:1 and 8:1, and even more
preferably between 1.7:1 and 6.5:1. Under these conditions, the
mean particle size of the additive polymer is 220-350 nm. The melt
viscosities are extrapolated to measurement time zero and measured
at an oscillation rate of 2.4 Hz and a temperature equal to the
melting temperature of the matrix polymer plus 34.0.degree. C. (in
the case of polyethylene terephthalate, 290.degree. C.).
[0033] The quantity of the additive polymer to be added to the
matrix polymer is 0.05-5 wt % (with reference to the total weight
of the polymer mixture). For many applications, such as the
manufacture of POYs, it is sufficient to use additive polymer in
amounts of less than 1.5 wt % (frequently <1.0 wt %) at draw-off
speeds of more than 3500 m/min (and up to 6000 m/min and higher),
which results in considerable cost savings.
[0034] The mixing of the additive polymer with the matrix polymer
can be conducted in manner known to those skilled in the art. It is
described, for example, in WO 99/07 927 and DE 100 22 889, whose
disclosure is incorporated by reference.
[0035] The spinning of the polymer mixture occurs at temperatures
in the range of 220-320.degree. C., depending on the matrix
polymer.
[0036] A variety of chemically distinct additive polymers can be
employed in the method of the invention. Additive polymers that are
particularly suitable for use in the method of the invention
include, but are not limited to, the polymers and/or copolymers
listed below:
[0037] 1. A polymer prepared by the polymerization of monomers
having the general formula I: 1
[0038] where R.sup.1 and R.sup.2 are substituents consisting of the
optional atom C, H, O, S, P and halogen atoms, and the sum of the
molecular weight of R.sup.1 and R.sup.2 is at least 40. Examples of
monomer units include acrylic acid, methacrylic acid, styrene and
C.sub.1-3 alkyl substituted styrenes, and CH.sub.2.dbd.CR--COOR',
where R is --H or --CH.sub.3, and R' is C.sub.1-15 alkyl,
C.sub.5-12 cycloalkyl, or C.sub.6-14 aryl residue.
[0039] 2. A copolymer of monomer units A and B, wherein,
[0040] A=acrylic acid, methacrylic acid or CH.sub.2.dbd.CR--COOR',
where R is --H or --CH.sub.3, and R' is C.sub.1-15 alkyl,
C.sub.5-12 alkyl residue, or C.sub.6-14 aryl,
[0041] B=styrene or C.sub.1-3 alkyl substituted styrenes,
[0042] and wherein the copolymer consists of 60-98 wt % A and 2-40
wt % B, preferably 83-98 wt % A and 2-17 wt % B, and more
preferably 90-98 wt % A and 2-10 wt % B (total=100 wt %).
[0043] 3. A copolymer of monomer units C and D, wherein,
[0044] C=styrene or C.sub.1-3 alkyl substituted styrenes,
[0045] D=one or more monomers having formula II, III, or IV 2
[0046] wherein R.sup.3, R.sup.4 and R.sup.5 are independently H,
C.sub.1-15 alkyl, C.sub.6-14 aryl, or C.sub.5-12 cycloalkyl, and
where the copolymer consists of 15-95 wt % C and 2-80 wt % D,
preferably of 50-90 wt % C and 10-50 wt % D, and most preferably
70-85 wt % C and 15-30 wt % D, and where the total of C and D is
100 wt %.
[0047] 4. A copolymer of monomer units E, F, G, and H, wherein
[0048] E=acrylic acid, methacrylic acid, or CH.sub.2.dbd.CR--COOR',
where R is --H or --CH.sub.3, and R' is C.sub.1-15 alkyl,
C.sub.5-12 cycloalkyl, or C.sub.6-14 aryl,
[0049] F=styrene or C.sub.1-3 alkyl substituted styrene,
[0050] G=one or more monomers having formula II, III, or IV (shown
above),
[0051] H=one or more ethylenically unsaturated monomers (which are
optionally co-polymerized with E, F, and/or G) selected from the
group consisting of .alpha.-methylstyrene, vinyl acetate, acrylic
acid esters and methacrylic acid esters differing from E,
acrylonitrile, acrylamide, methacrylamide, vinyl chloride,
vinylidene chloride, halogen substituted styrenes, vinyl ethers,
isopropylene ethers, and dienes,
[0052] wherein the copolymer consists of 30-99 wt % E, 0-50 wt % F,
0-50 wt % G and 0-50 wt % H, preferably 45-97 wt % E, 0-30 wt % F,
3-40 wt % G and 0-30 wt % H, and more preferably 60-94 wt % E, 0-20
wt % F, 6-30 wt % G and 0-20 wt % H, where the total of E, F, G and
H is 100 wt %.
[0053] Component H is an optional component. Although the
advantages provided by the method of the invention are achievable
using copolymers of E-G, the advantages are also obtained when
copolymers are formed with the monomers from group H.
[0054] Preferably, component H is chosen in such a manner that it
has no disadvantageous effect on the properties of the
copolymers.
[0055] Some of the purposes for which component H can be used
include: (a) to modify the properties of the copolymer in the
desired manner, for example, by increasing or improving the flow
properties when the copolymer is heated to the melting temperature,
(b) to reduce residual dye in the copolymer, and (c) to introduce a
certain degree of crosslinking into the copolymer by using a
poly-functional monomer.
[0056] Moreover, H can also be chosen in such a manner that
copolymerization of components E-G occurs or is promoted only in
the presence of H. For example MSA and MMA by themselves do not
copolymerize, although they undergo copolymerization if a third
component, such as styrene, is added.
[0057] "H" monomers that are suitable for this purpose include
vinyl ester, esters of acrylic acid (e.g., methyl acrylate and
ethyl acrylate), esters of methacrylic acid (different from methyl
methacrylate) (e.g., butyl methacrylate and ethyl hexyl
methacrylate), acrylonitrile, acrylamide, methacrylamide, vinyl
chloride, vinylidene chloride, styrene, .alpha.-methylstyrene, and
the various halogen substituted styrenes, vinyl- and isopropenyl
ethers, diones (e.g., 1,3-butadiene and divinylbenzene). Color
reduction of the polymers can be achieved, for example, in a
particularly preferred manner by using an electron rich monomer,
such as vinyl ether, vinyl acetate, styrene or
.alpha.-methylstyrene.
[0058] Among the compounds of H, use of aromatic vinyl monomers,
such as styrene or .alpha.-methylstyrene, are particularly
preferred.
[0059] Manufacture of the additive polymers to be used according to
the invention is known and any such method can be employed. The
additive polymers can be manufactured by substance, solution,
suspension or emulsion polymerization. Useful teachings of
substance polymerization can be found in Houben-Weyl, Volume E20,
Part 2 (1987), pp. 1145 ff. Teachings of solution polymerization
can be found in the same volume on pages 1156 ff. In the same
volume, the suspension polymerization technique is described on
pages 1149 ff, while the emulsion polymerization is described and
explained in the same volume on pages 1150 ff.
[0060] It is particularly preferred to use bead polymers whose
particle size is in a particularly advantageous range. It is
particularly preferred that the additive polymers to be used, for
example, by mixing in the melt of fiber polymers, are in the form
of particles having a mean particle size of 0.1-1.0 mm. However,
larger or smaller beads can also be used.
[0061] All the copolymers according to the invention are
commercially available or can be manufactured by methods routine to
those skilled in the art.
[0062] For polymer mixtures made of polyethylene terephthalate for
textile applications, such as POYs with a limit viscosity value of
approximately 0.55-0.75 dL/g and additive polymers of type 1, 2, 3
or 4, additive polymers with viscosity values of 70-130 cm.sup.3/g
are preferred.
[0063] In one embodiment of the method of the invention, an
additive polymer obtained by multiple initiation is added. The term
"multiple initiation" includes both single and multiple
post-initiation of a radical-induced polymerization, i.e., it
includes single or multiple renewed addition of initiator at later
reaction times as well as radical induced polymerization in the
presence of a mixture comprising at least two initiators with
different half lives (which are particularly preferred in the
context of the present invention). For the purposes of the
invention, half lives of initiators are considered different when
they possess different half lives at the same temperature or the
same half life at different temperatures. It is preferred to use
initiators with a half life of one hour in temperature ranges that
are separated by at least 10.degree. C. It is possible to use a
single compound as initiator for a single temperature. It is also
possible to use two or more initiators, each with an appropriate
half life for a particular temperature range.
[0064] Such polymerizations are described, for example, in the
Patents U.S. Pat. No. 4,588,798, U.S. Pat. No. 4,605,717, EP 489
318, DE 199 17 987, and the documents cited therein. The
disclosures of these patents is incorporated herein by
reference.
[0065] In the context of the present invention it has been found to
be particularly advantageous to use an initiator mixture that uses
an initiator I.sub.1 with a half life T.sub.1 of one hour in the
range 70-85.degree. C., and an additional initiator I.sub.2 with a
half life T.sub.2 of one hour in the range 85-100.degree. C. Other
initiators I.sub.n that can optionally be used preferably have
degradation temperatures T.sub.n between T.sub.1 and T.sub.2.
[0066] The quantity of the initiator mixture to be used can be
varied within relatively broad ranges. Varying the amount of
initiator facilitates control of the polymerization time and
influences the polymerization temperature. The quantities of
indicators used according to the invention are given in parts by
weight of initiator per 100 parts by weight of monomer. It is
advantageous to use a total quantity of initiator mixture of
approximately 0.05-1.0 parts by weight per 100 parts by weight of
monomer, preferably 0.05-0.5 part by weight, and, most preferably,
0.15-0.4 part by weight per 100 parts by weight of monomer.
[0067] The ratio by weight of the individual initiators to each
other in the initiator mixture can also be varied within relatively
broad ranges. It is preferred to use a ratio by weight of the
individual initiators to each other in the range from 1:1 to 1:10,
preferably 1:1 to 1:4. Suitable quantities and mixing ratios can be
easily and routinely determined with simple preliminary tests.
[0068] Suitable initiators that can be used to synthesize additive
polymers for use in the invention include conventional initiators
that are used for radical formation in radical initiated
polymerizations. They include compounds such as organic peroxides
(e.g., dicumyl peroxide), diacyl peroxides (e.g., dilauroyl
peroxide), peroxydicarbonates (e.g., diisopropyl
peroxydicarbonate), peresters (e.g., tert-butylperoxy-2-ethyl-
hexanoate), and similar compounds. Other compound types that are
capable of forming radicals are also suitable for use in the
present invention. In particular, such compounds include azo
compounds such as 2,2'-azobisisobutyronitrile and
2,2'-azobis(2,4-dimethylvaleronitrile.
[0069] It has been found that mixtures whose components are chosen
from the following initiators are particularly advantageous (the
indicated temperatures are those at which the half life of the
corresponding initiator is 1 hour):
[0070] tert-amylperoxy pivalate, 71.degree. C.,
[0071] 2,2'-azobis-(2,4-dimethylvaloemitrile), 71.degree. C.,
[0072] di-(2,4-dichlorobenzoyl) peroxide, 72.degree. C.,
[0073] tert-butylperoxy pivalate, 74.degree. C.,
[0074] 2,2'-azobis-(2-amidinopropane) dihydrochloride, 74.degree.
C.,
[0075] di-(3,5,5-trimethylhexanoyl) peroxide, 78.degree. C.,
[0076] dioctanoyl peroxide, 79.degree. C.,
[0077] dilauroyl peroxide, 80.degree. C.,
[0078] didecanoyl peroxide, 80.degree. C.,
[0079] 2,2'-azobis-(N,N'-dimethylene isobutyramidine), 80.degree.
C.,
[0080] di-(2-methylbenzoyl) peroxide, 81.degree. C.,
[0081] 2,2'-azobisisobutyronitrile, 82.degree. C.,
[0082] 2,2'-dimethylazobisisobutyrate, 83.degree. C.,
[0083] 2,2'-azobis-(2-methylbutyronitrile), 84.degree. C.,
[0084] 2,5-dimethyl-2,5-di-(2-ethylheanoylperoxy) hexane,
84.degree. C.,
[0085] 4,4'-azobis-(cyanopentanoic acid), 86.degree. C.,
[0086] di-(4-methylbenzoyl) peroxide, 89.degree. C.,
[0087] dibenzoyl peroxide, 91.degree. C.,
[0088] tert-amylperoxy-2-ethylhexanoate, 91.degree. C.,
[0089] tert-butylperoxy-2-ethylhexanoate, 92.degree. C.,
[0090] tert-butylperoxy isobutyrate, 96.degree. C.
[0091] Peroxide initiators are particularly preferred.
[0092] Polymerization of additive polymers can be carried out under
substantially isothermal conditions partly or over broad ranges. In
a particularly preferred embodiment of the present invention,
polymerization is carried out in at least two steps. In the first
step, polymerization is carried out first at a lower temperature,
preferably 60 to less than 85.degree. C. In the second step,
polymerization is carried out at a higher temperature, preferably
at 85-120.degree. C.
[0093] It is preferred that the additive polymer have a residual
monomer content of less than 0.62 wt %, more preferably less than
0.47 wt %, and even more preferably less than 0.42 wt %, in each
case with reference to the total weight of the additive polymer. In
a particularly preferred embodiment, the residual monomer content
of the additive polymer is less than 0.37 wt %, more preferably
less than 0.30 wt %, even more preferably less than 0.25 wt %, and
yet even more preferably less than 0.20 wt %, in each case with
reference to the total weight of the additive polymer.
[0094] The residual monomer content in the additive polymer refers
to the quantity of monomer that remains after polymerization and
separation of the additive polymer. In the case of polymers
manufactured by radical induced polymerization, the residual
monomer content is usually in the range of 0.65-1.0 wt % with
reference to the total weight of the polymer. Methods for the
reduction of the residual monomer content of a polymer are known to
those skilled in the art. For example, monomer content can be
reduced by degassing polymer melts, preferably in the extruder,
directly before the spinning. In addition, it is also possible to
obtain polymers with a reduced residual monomer content by a
suitable choice of the polymerization parameters.
[0095] Moreover, it is extremely advantageous to admix a
flowability promoting agent with the additive polymer. The term
flowability promoting agents here refers to all process agents that
are admixed in small quantities, in powdered or granulated form
(particularly hygroscopic substances), in order to prevent clumping
or caking together, and thus to guarantee free flow. Flowability
promoting adjuvants (also called anti-adhesive agents, anti-caking
agents, or fluidizers) useful in the present invention include
water insoluble, hydrophobicity producing, or humidity adsorbing
powders such as diatomaceous earth, pyrogenic salicylic acids,
tricalcium phosphate, calcium silicates, Al.sub.2O.sub.3, MgO,
MgCO.sub.3, ZnO, stearates, and fatty amines (see CD Rompp Chemie
Lexikon [Rompp Chemistry Lexicon]--Version 1.0, Stuttgart/New York:
Georg Thieme Verlag, 1995).
[0096] Such flowability promoting adjuvants have been shown to be
suitable only under certain conditions, however, because they can
be detrimental to the spinning process. They can become deposited
in the spinning device and lead to clogging of the lines and
nozzles and, thus, to operational disfunctions. There is also the
risk that as a result of the "extraneous substances," the material
properties of the resulting synthetic fibers are worsened, and the
filament rupture rate during spinning increased.
[0097] Therefore, according to the invention, polymers and/or
copolymers are particularly preferred as flowability promoting
agents as they do not introduce the same deleterious consequences
as the aforementioned agents. The polymers and/or copolymers listed
below have been found to be particularly advantageous:
[0098] 1. A polymer prepared by the polymerization of monomers
having the general formula (I): 3
[0099] where R.sup.1 and R.sup.2 are substituents consisting of the
optional atom C, H, O, S, P and halogen atoms, and the sum of the
molecular weight of R.sup.1 and R.sup.2 is at least 40. Examples of
monomer units include acrylic acid, methacrylic acid, styrene,
C.sub.1-3 alkyl substituted styrenes, and CH.sub.2.dbd.CR--COOR',
where R is --H or .dbd.CH.sub.3, and R' is C.sub.1-15 alkyl,
C.sub.5-12 alkyl, or C.sub.6-14 aryl.
[0100] 2. A copolymer containing the following monomer units:
[0101] A=acrylic acid, methacrylic acid or CH.sub.2.dbd.CR--COOR',
where R is --H or --CH.sub.3, and R' is C.sub.1-15 alkyl,
C.sub.5-12 cycloalkyl, or C.sub.6-14 aryl,
[0102] B=styrene or C.sub.1-3 alkyl substituted styrenes,
[0103] where the copolymer consists of 60-98 wt % A and 2-40 wt %
B, preferably 83-98 wt % A and 2-17 wt % B, and more preferably
90-98 wt % A and 2-10 wt % B (total=100 wt %).
[0104] 3. A copolymer containing the following monomer units:
[0105] C=styrene or C.sub.1-3 alkyl substituted styrenes,
[0106] D=one or more monomers having formula II, III, or IV
(above)
[0107] where the copolymer consists of 15-95 wt % C and 2-80 wt %
D, preferably 50-90 wt % C and 10-50 wt % D, and more preferably
70-85 wt % C and 15-30 wt % D, where the total of C and D is 100 wt
%.
[0108] 4. A copolymer containing the following monomer units:
[0109] E=acrylic acid, methacrylic acid, or CH.sub.2.dbd.CR--COOR',
where R is --H atom or --CH.sub.3, and R' is C.sub.1-15 alkyl,
C.sub.5-12 cycloalkyl, or C.sub.6-14 aryl,
[0110] F=styrene or C.sub.1-3 alkyl substituted styrene,
[0111] G=one or more monomers having formula II, III or IV
(above),
[0112] H=one or more ethylenically unsaturated monomers, which can
be copolymerized with E, F, and/or G, selected from the group
consisting of .alpha.-methylstyrene, vinyl acetate, acrylic acid
esters and methacrylic acid esters differing from E, acrylonitrile,
acrylamide, methacrylamide, vinyl chloride, vinylidene chloride,
halogen substituted styrenes, vinyl ethers, isopropylene ethers,
and dienes,
[0113] where the copolymer consists of 30-99 wt % E, 0-50 wt % F,
0-50 wt % G and 0-50 wt % H, preferably 45-97 wt % E, 0-30 wt % F,
3-40 wt % G and 0-30 wt % H, and more preferably 60-94 wt % E, 0-20
wt % F, 6-30 wt % G and 0-20 wt % H, where the total of E, F, G and
H is 100 wt %.
[0114] Component H is an optional component. Although the
advantages that can be achieved according to the invention can be
achieved by using copolymers, which comprise components from the
groups E-G, the advantages achievable according to the invention
are also obtainable if other monomers from group H are included in
the copolymers.
[0115] Component H is preferably chosen in such a manner that it
has no disadvantageous effect on the properties of the copolymers
to be used according to the invention.
[0116] Some of the purposes for which component H can be used
include: to modify the properties of the copolymer in the desired
manner, e.g., by increasing or improving the flow properties when
the copolymer is heated to the melting temperature, to reduce
residual dye in the copolymer, or to introduce, by using a
polyfunctional monomer, a certain degree of crosslinking into the
copolymer.
[0117] Moreover, H can also be chosen in such a manner that
copolymerization of components E-G occurs or is promoted only in
the presence of H. For example MSA and MMA by themselves do not
copolymerize although they undergo copolymerization if a third
component, such as styrene, is added.
[0118] Monomers that are suitable for this purpose include vinyl
ester, esters of acrylic acid (e.g., methyl acrylate and ethyl
acrylate), esters of methacrylic acid (which differ from methyl
methacrylate) (e.g., butyl methacrylate and ethyl hexyl
methacrylate), acrylonitrile, acrylamide, methacrylamide, vinyl
chloride, vinylidene chloride, styrene, .alpha.-methylstyrene, and
the various halogen substituted styrenes, vinyl- and isopropenyl
ethers, dienes (e.g., 1,3-butadiene), and divinylbenzene. Color
reduction of the polymers can be achieved in a particularly
preferred manner, for example, by using an electron rich monomer
such as vinyl ether, vinyl acetate, styrene or
.alpha.-methylstyrene.
[0119] It is particularly preferred to use, among the compounds of
component H, aromatic vinyl monomers, such as, for example, styrene
or .alpha.-methylstyrene.
[0120] Methods of manufacturing the aforementioned flowability
promoting agents is known to those skilled in the art. They can be
manufactured by substance, solution, suspension or emulsion
polymerization. Useful teaching on substance polymerization can be
found in Houben-Weyl, Volume E20, Part 2 (1987), pages 1145 ff.
Teachings concerning the solution polymerization can be found in
the same volume on pages 1156 ff. The suspension polymerization
technique is described in the same volume on pages 1149 ff, while
the emulsion polymerization is described and explained in the same
volume on pages 1150 ff. Optionally, the polymers can be
additionally milled.
[0121] It is particularly preferred to use flowability promoting
agents whose particle size is in a particularly advantageous range.
It is particularly preferred for the flowability promoting agents
to be in the form of particles having a mean diameter of 0.01 to
less than 100 .mu.m. However, flowability promoting agents with
larger or smaller particle sizes can also be used.
[0122] Imidized copolymer of types 3 and 4, above, can be
manufactured from monomer imides and also by the subsequent
complete or, preferably, partial imidization of a copolymer
containing the corresponding maleic acid derivative. These
flowability promoting agents are manufactured, for example, by
complete, or, preferably, partial conversion of the corresponding
copolymer in the melt phase with ammonia or with a primary
alkylamine or arylamine, e.g., aniline (Encyclopedia of Polymer
Science and Engineering, Vol. 16 (1989), Wiley-Verlag, page 78).
The resulting copolymers optionally can be additionally milled.
[0123] All the copolymers according to the invention as well as
their non-imidized starting polymers, to the extent indicated, are
commercially available or they can be manufactured by routine
methods by those skilled in the art.
[0124] In the context of the present invention, flowability
promoting agents that have substantially the same chemical
composition as the additive polymer used have been shown to be
particularly advantageous. The flowability promoting agents and the
additive polymer used advantageously contain at least 50 wt %,
preferably at least 60 wt %, more preferably at least 70 wt %, and
even more preferably at least 80 wt % (in each case with reference
to the total weight of the flowability promoting agents or of the
additive polymer used) of the same repeating monomer units.
[0125] Particularly advantageous results according to the invention
are achieved if the flowability promoting agents and the additive
polymer used comprise at least 90 wt %, preferably at least 95 wt
%, and more preferably at least 97 wt % of the same repeating
units, in each case with reference to the total weight of the
flowability promoting agent or the additive polymer used. In a
particularly preferred embodiment of the present invention the
polymer composition of the flowability promoting agent and that of
the additive polymer used are comprised of the same repeating
monomer units.
[0126] In the context of the present invention it is advantageous
to use a flowability promoting agent that has a weight average
molecular weight that is similar to that of the additive polymer
used. Advantageously, the weight average molecular weight of the
flowability promoting adjuvant differs by less than 50%, preferably
by less than 30%, and more preferably by less than 20% from that of
the additive polymer used.
[0127] The preferred concentration range of the flowability
promoting adjuvant in additive polymer is 0.05-5.0 wt %, preferably
0.05-1.0 wt %, in each case with respect to the total weight of
additive polymer and flowability promoting adjuvant, and depends on
the surface (and thus the mean diameter) of the additive polymers.
In the case of a bead polymer having a mean particle size of 0.7
mm, it is preferred to use a concentration of the flowability
promoting agent of 0.05-0.3 wt %. With decreasing diameter of the
beads the required concentration of flowability promoting adjuvant
to achieve the flow promoting effect increases. If the
concentration of the flowability promoting adjuvant is too low, the
flow promoting effect is incomplete. By contrast, if the
concentrations of the flowability promoting agents are too high, no
additional improvement in the flow behavior is achieved, although a
strong, industrially undesirable, dust formation occurs due to the
excess, finely divided flowability promoting adjuvant powder.
[0128] It is more advantageous to manufacture the flowability
promoting adjuvant by an emulsion polymerization method, followed
by isolation by spray drying. The spray drying can be carried out
in a known manner. Examples of descriptions of spray drying can be
found in DE 332 067 or in Ullmann's Encyclopedia of Industrial
Chemistry, 5.sup.th edition (1988), B 2, pp. 4-23. Depending on the
spray aggregate (single substance nozzle, two substance nozzle or
atomization disk), particles having a mean particle diameter of
20-300 .mu.m are obtained.
[0129] The mixture of additive polymer and flowability promoting
adjuvant to form an elongation increasing agent (which is
preferably homogenous as possible) can be carried out in a manner
known to those skilled in the art. Details can be found, for
example, in Ullmanns Enzyklopdie der technischen Chemie, 5.sup.th
edition (1988), as well as in Rompps Chemie Lexikon (CD)--Version
1.0, Stuttgart/New York: Georg Thieme Verlag, 1995.
[0130] It has been found to be very advantageous to mix the
additive polymer, which is preferably dried using a fluidized bed
dryer, and the spray dried flowability promoting adjuvant using a
fluidized bed dryer. Details on the fluidized bed process can be
found in the specialty literature, e.g., in Ullmanns Encyclopedia
of Industrial Chemister, 5.sup.th edition (1988), as well as in
Rompps Chemie Lexikon (CD)--Version 1.0, Stuttgart/New York: Georg
Thieme Verlag, 1995.
[0131] The elongation increasing agent to be in the invention is
not granulated, in contrast to the state of the art. In this
context, the term granulation refers to the manufacture of
so-called pellets (granulates) having the same shape and size. The
polymer to be granulated is usually melted in a one- or double worm
extruder and introduced into a pelletization machine. Comminution
can be carried out by cold pelletization or hot pelletization. In
cold pelletization, strands, strips or thin films are manufactured
by the granulation nozzle, which are then comminuted after
solidification by means of rotating knives. In hot pelletization,
the plasticized polymer is pressed through the nozzle and the
exiting strand is comminuted by means of a rotating knife, which is
usually attached to the nozzle plate. The cooling of the melt
occurs after the pelletization, usually either with air or
water.
[0132] The manufacture of the synthetic fibers from polymer
mixtures according to the invention by melt spinning can be carried
out using art recognized spinning installations, as described, for
example, in the Patents DE 199 37 727 (staple fibers), DE 199 37
728 and DE 199 37 729 (industrial yarns) and WO 99/07 927 (POYs),
the disclosures of which are incorporated herein by reference.
[0133] Since the methods according to the invention have been shown
to be particularly advantageous for the manufacture of POYs, its
manufacture is describe below. The application of the method for
the manufacture of other synthetic fibers will be immediately
obvious to a person skilled in the art.
[0134] Preferably, the melt spinning of POYs is carried out at
spinning draw-off speeds of at least 2500 m/min. The filter unit
can be fitted with filtering devices and/or loose filter media (for
example, steel sand) in an art recognized manner.
[0135] After completion of the shearing and filtration treatment,
the molten polymer mixture is pressed in the nozzle unit through
the boreholes of the nozzle plate. In the cooling zone that
follows, the melt filaments are cooled by means of cooling air to a
temperature below their softening temperature to avoid adhesion or
jamming to the following filament guide organ. The form of the
cooling zone is not critical, provided a homogeneous stream of air
that evenly passes through the filament bundle is maintained. Thus,
an air rest zone can be provided immediately under the nozzle plate
to delay the cooling. The cooling air can be supplied by means of
diagonal or radial ventilation from an air conditioner system, or
by means of a cooling pipe from the environment with unaided
suction.
[0136] After cooling, the filaments are bundled and spinning oil is
applied. To achieve this, oiling stones are supplied with the
spinning oil by metering pumps in the form of an emulsion. The
prepared yarns advantageously run through an entangling device to
improve the filament closure. It is also possible for handling and
safety devices to be provided before the filament reaches the
winding unit, where it is spooled onto cylindrical spool bodies to
form packets. The circumferential speed of the filament packet is
automatically regulated and is equal to the spooling speed. The
draw-off speed of the filament can be 0.2-2.5% higher than the
spooling speed due to its changing orientation. Optionally, driven
rollers can be used after preparation or before spooling. The
circumferential speed of the first roller system is called the
draw-off speed. Additional rollers can be used for stretching or
relaxing.
[0137] Due to the immiscibility of the matrix polymer and additive
polymer, immediately after the exit of the polymer mixture from the
spinning nozzle the additive polymer forms ball-like or
longitudinally shaped particles in the matrix polymer.
Advantageously, the length/diameter ratio of the particles is
>2. The best conditions were found to correspond to those in
which the mean particle size (arithmetic mean) d.sub.50.ltoreq.400
nm and the fraction of particles >1000 nm in sample cross
section was less than 1%.
[0138] It was possible to analytically show how these particles
were influenced by the spinning traction. Examination of the
spinning filaments by TEM [transmission electron microscopy] has
shown that the structure was fibril like. The mean diameter of the
fibrils was estimated to be approximately 40 nm. The
length/diameter ratio of the fibrils was >50. If these fibrils
are not formed, if the additive particles exiting from the spinning
nozzle have too large a diameter, or if the particle size
distribution is too irregular (which was the case if the viscosity
ratio was insufficient), the beneficial effect of the additive
particles was lost.
[0139] Roller action described in the literature could not be
repeated with the additive polymer according to the invention.
Microscopic evaluations of fiber cross sections and longitudinal
sections suggest that the spinning traction tension is transferred
to the forming additive polymer fibrils, and the polymer matrix
undergoes distortion with low tension. This results in deformation
of the matrix under conditions that result in a reduction of
orientation and suppression of spinning induced crystallization. It
is useful to evaluate the effect on spinning filament formation and
processing behavior.
[0140] Furthermore, a additive polymer flow activation energy of at
least 80 kJ/mol is preferred to achieve the beneficial effects of
additive polymers according to the invention; that is a higher flow
activation energy than that of the matrix polymers. Under such
circumstances the additive polymer fibrils solidify before the
matrix polymers and absorb a considerable portion of the applied
spinning tension. As a result, it is possible to achieve the
desired increase in capacity of the spinning installation.
[0141] A preferred embodiment of the invention described above is
similarly suitable for the rapid spinning of POY filaments having a
POY filament titer of .gtoreq.3-20 dtex, as well as of POY filament
titers <3 dtex, in particular microfilaments with 0.2-2.0
dtex.
[0142] Due to the additive polymer, the filament rupture rate of
fibers made according to the invention is considerably decreased
compared to known methods. Advantageously, POYs produced according
to the invention having a titer >3 dtex have a filament rupture
rate that is less than 0.75 ruptures per ton of polymer mixture,
preferably less than 0.5 ruptures/per ton of polymer mixture, and
more preferably less than 0.4 ruptures per ton of polymer
mixture.
[0143] Synthetic filaments obtained by the method of the invention
can be used directly, or they can be further processed in art
recognized manners. They are particularly advantageously used for
the manufacture of staple fibers. In this context, reference is
made, for example, to Patent DE 199 37 727 and the documents cited
therein, for further detail on the manufacture of staple fibers of
the state of the art.
[0144] Advantageously, POYs manufactured by the method according to
the invention can be stretched or stretch textured. In this
context, the following observations are important for the further
processing of the spinning filament in the stretch texturing
process at high speeds: spun filaments according to the invention,
as preliminary yarn for stretch texturing--usually called POY--are
preferably manufactured with draw-off speeds .gtoreq.2500 m/min,
preferably >3500 m/min, more preferably >4000 m/min. These
yarns must have a physical structure that is characterized by a
specific degree of orientation and a low crystallization. The
following parameters have been shown to be useful for their
characterization: elongation at break, birefringence,
crystallization, and shrinkage after boiling. The polymer mixture
according to the invention is characterized by an elongation at
break of the polymer spun filaments (POY) of at least 85% and at
most 180%. The shrinkage after boiling is 32-69%, the birefringence
is between 0.030 and 0.075, the crystallinity is less than 20%, and
the rupture strength at least 17 cN/tex. It is preferred that the
elongation at break of the polymer spun filaments be 85-160%.
Particularly advantageous conditions exist if the elongation at
break of the polymer spun filaments is between 109 and 146%, and,
at the same time, the rupture strength is at least 22 cN/tex and
the uster value is at most 0.7%.
[0145] Synthetic POYs obtained in this manner are particularly
suitable for further processing in a stretching process or stretch
texturing process. One also observes a lower number of filament
ruptures during the further processing. The stretch texturing is
carried out speeds dependent upon the filament titer type. For
normal titer filaments .gtoreq.2 dtex per filament (final titer),
speeds of .gtoreq.750 m/min and preferably .gtoreq.900 m/min are
used. For microfilaments and fine titers (final titer) <2 dtex,
speeds of 400-750 m/min are preferred. The method can be used
advantageously for these titers and in particular for
microfilaments with 0.15-1.10 dtex (final titer) per filament.
[0146] The stretch ratios to be used for the specified spun
filaments are 1.35-2.2, where it is preferred to use stretch ratios
in the upper portion of the range for lower degrees of orientation,
and vice versa. In stretch texturing, the stretch ratio is
influenced by tension surging as a function of the speed of
operation. Therefore, it is particularly preferred to use stretch
ratios according to the formula:
Stretch ratio=5.times.10.sup.-4.multidot.w+b
[0147] where
[0148] w=stretch texturing speed in m/min
[0149] b=constant, between 1.15 and 1.50.
[0150] The invention is further explained below by means of an
example and comparative example, although the inventive method is
not limited to this example.
EXAMPLES
[0151] The indicated property values, as well as the values
indicated above, were determined as follows:
[0152] The residual monomer content of methyl methacrylate and
styrene was measured by gas chromatographic head space analysis, a
method for the determination of volatile components in fluids and
solids (including monomers in thermoplastics). The residual monomer
content of N-cyclohexylmaleinimide was determined by gas
chromatography of a solution of the polymer in dichloromethane.
[0153] The mean particle diameter of the spray dried flowability
promoting adjuvant was determined by laser bending spectroscopy
using a Mastersizer Microplus from the company Malvem (measurement
range: 0.05-555 .mu.m).
[0154] The mean particle diameter of the spun filament additive
beads was determined by sieve analysis using an Alpine air jet
sieving machine (type A 200 LS).
[0155] The intrinsic viscosity was determined using a solution of
0.5 g polyester in 100 mL of a mixture made of phenol and
1,2-dichlorobenzene (3:2 parts by weight) at 25.degree. C.
[0156] The viscosity value VZ (also called Staudinger function) is
the concentration-related relative change in viscosity of a 0.5%
solution of copolymer in chloroform with reference to the solvent,
where the passage times were determined in the Ubbelohde
viscosimeter with suspended ball level, Schott type No. 53203 and
capillaries 0c according to the DIN standard 51562 at 25.degree. C.
Chloroform was used as solvent. 2 V Z = ( t t 0 - 1 ) 1 c
[0157] where
[0158] t=passage time of the polymer solution in seconds
[0159] t.sub.0=passage time of the solvent in seconds
[0160] c=concentration in g/100 cm.sup.3
[0161] For the determination of the melt viscosity (initial
viscosity), the polymer was dried in a vacuum to a water content
.ltoreq.1000 ppm (polyester.ltoreq.50 ppm). The polymer was then
introduced into a cone plate rheometer, type UM100, Physica
Megtechnik GmbH, Stuttgart/DE, using a nitrogen cloud on a
temperature regulated measurement plate. In this process, the
measurement cone (MK210) was positioned after the melting of the
sample (approximately after 30 sec) onto the measurement plate. The
measurement was started after an additional heating period of 60
sec (measurement time=0 sec). The measurement temperature was
290.degree. C. for polyethylene terephthalate and additive polymers
added to the polyethylene terephthalates, or it was equal to the
melting temperature (method, see below) of the polymer in question
plus 34.0.degree. C. The measurement temperature so established
corresponds to the typical processing or spinning temperature of
the polymer in question. The sample quantity was chosen in such a
manner that the rheometer gap was completely filled. The
measurement was carried out at an oscillation a frequency of 2.4 Hz
(corresponding to a shearing rate of 15 sec.sup.-1) and a
deformation amplitude of 0.3. The complex viscosity as a function
of measurement time was determined. The initial viscosity was then
calculated by linear regression to the measurement time zero.
[0162] For determination of the melting temperature of the polymer,
the polymer sample was first melted at 310.degree. C. for 1 min.
and then immediately quenched to room temperature. The melting
temperature was determined by DSC (differential scanning
calorimetry) using a heating rate of 10.degree. C./min. The
preliminary treatment and measurement were carried out under a
nitrogen.
[0163] The titer was determined in a known manner using a precision
reel and a weighing device. The preliminary tension for preoriented
filaments (POYs) was 0.05 cN/dtex and 0.2 cN/dtex for draw textured
yarn (DTY).
[0164] The rupture strength and elongation at break were determined
in a Statimat measurement apparatus under the following conditions:
the clamping length was 200 mm for POY and 500 mm for DTY, the
measurement speed was 2000 mm/min for POY and 1500 mm/min for DTY,
and the preliminary tension was 0.05 cN/dtex for POY and 0.2
cN/dtex for DTY. By dividing the values for the maximum rupture
load by the titer, the rupture strength was determined and the
elongation at break was evaluated under a maximum load.
Example 1
Comparative Example
[0165] Polyethylene terephthalate flakes having a water content of
less than 35 ppm, a limit viscosity value of 0.64 dL/g, and a melt
viscosity (at 290.degree. C.) of 250 Pas were introduced into the
inlet of an extruder. A drop pipe was located vertically with
respect to the direction of conveyance of the extruder worm and in
a centered position with respect to the extruder inlet by means of
which the additive, which had been dried to a residual humidity of
<0.1 wt %, was added to the polyester flakes into the inlet area
above the extruder worm with a gravimetric metering system.
[0166] As additive, a bead polymer based on
MMA/styrene/N-cyclohexylmalein- imide and prepared in a suspension
was used. The terpolymer used consisted of 89.2 wt % methyl
methacrylate, 8.8 wt % styrene and 2 wt % N-cyclohexylmaleinimide,
had a viscosity value VZ of approximately 101 cm.sup.3/g and a melt
viscosity (at 290.degree. C.) of approximately 1400 Pas.
[0167] The MMA/styrene/N-cyclohexylmaleinimide additive with VZ 101
cm.sup.3/g was obtained as follows:
[0168] a mixture consisting of 525 kg of completely desalted water,
0.071 kg of KHSO.sub.4, and 13 g of a 13% aqueous solution of a
polyacryhic acid was heated to 40.degree. C. in a 1000-L
polymerization vessel with heating/cooling jacket equipped with
stirrer, reflux cooler, and thermometer. Under stirring, 525 kg of
a mixture of 88.68 parts by weight of methyl methacrylate (MMA),
8.75 parts by weight of styrene, 1.99 parts by weight of
N-cyclohexylmaleinimide, 0.14 parts by weight of thioglycolic acid
2-hexylethyl ester, 0.09 part by weight of tert-dodecylmercaptan,
0.05 part by weight of stearic acid, and 0.3 part by weight of
dilauroyl peroxide were added. The preparation was polymerized for
130 min at 80.degree. C. and for 60 min at 98.degree. C. and then
cooled to room temperature. The polymer beads were removed by
filtration, thoroughly washed with completely desalted water, and
dried in a fluidized bed dryer at 80.degree. C.
[0169] The dried polymer beads were then mixed with 0.1 part by
weight of a spray dried MMA/styrene emulsion polymer and mixed for
approximately 5 min in a fluidized bed dryer.
[0170] The MMA/styrene emulsion polymer used as antistatic agent or
flowability promoting adjuvant was obtained as follows:
[0171] 80 kg of completely desalted water, 0.016 kg of 75% sodium
diisooctylsulfosuccinate and 0.056 kg of sodium peroxodisulfate
were introduced into a 500-L polymerization vessel with
heating/cooling jacket equipped with stirrer, reflux cooler and
thermometer and heated to an internal temperature of 92.degree. C.
In a second reactor equipped with a stirrer, an emulsion of 182.4
kg of methyl methacrylate, 17.6 kg of styrene, 0.080 kg of
thioglycolic acid 2-ethylhexyl ester in 120 kg of completely
desalted water, which contained 0.8 kg of sodium
diisooctylsulfosuccinate and 0.12 kg of sodium peroxodisulfate, was
prepared at room temperature. This emulsion was added by metering
into the polymerization vessel at a rate of 1.2 kg/min, which was
maintained at a polymerization temperature of approximately
92.degree. C. by heating or cooling. After the end of the addition
by metering, the reactor content was heated for an additional 30
min at an internal temperature of 92.degree. C.
[0172] The polymer dispersion obtained was then spray dried in a
Niro company manufactured spray tower manufactured equipped with an
atomization disk rotating at 15,000 m/min. The air added was at a
temperature of 180-190.degree. C.; the exiting air was at a
temperature of 75-80.degree. C. The dried MMA/styrene copolymer had
a mean particle size of d.sub.50=14 .mu.m.
[0173] The VZ of the spray dried MMA/styrene copolymer was 97
cm.sup.3/g.
[0174] The spray dried MMA/styrene copolymer was mixed, as already
described, at a concentration of 0.1 wt % with the
MMA/styrene/N-cyclohexylmaleinimide in a fluidized bed dryer at
room temperature for 5 min.
[0175] This process resulted in the production of 510 kg of polymer
beads with viscosity value according to DIN 7745 of 101 cm.sup.3/g,
a residual methyl methacrylate content of 0.47 wt %, and a mean
particle diameter of 0.75 mm. The residual styrene content was
below the detection limit of 0.05 wt %. The residual
N-cyclohexylmaleinimide content was below the detection limit of
0.1 wt %.
[0176] The additive was added at a concentration of 0.77 wt % (with
reference to the total quantity of the polymer mixture of polyester
and additive) and drawn off through the spinning system supplied by
the extruder. The total quantity of polymer mixture drawn off was
determined by the number of spinning pumps of the spinning system
described below in operation and the delivery of each spinning
pump. When all the spinning pumps were operated, a total quantity
of 304.5 kg/h of polymer mixture was drawn off by the spinning
system, and the additive was added by gravimetric metering in a
quantity of 2.34 kg/h into the extruder inlet.
[0177] The wave motion of the extruder worm at the extruder inlet
resulted in a premixing of the additive beads with the polyester
flakes. The polyester flakes and the additive beads were melted and
mixed together in the extruder, which was an LTM-24D/E8 spinning
extruder manufactured by Barmag AG, Remscheidt/DE. The first
polymer mixture was drawn off at a temperature of 290.degree. C.
and a pressure of 180 bar, conveyed as a melt stream at 304.5 kg/h
through the melt line, and subjected to filtration using a 20-.mu.m
filter cartridge.
[0178] The filtered first polymer mixture was introduced into a
static mixer of the SMX type manufactured by Sulzer AG with an
internal diameter of 52.5 mm and a length of 525 mm, where it was
homogenized and dispersed to form a second polymer mixture.
[0179] This second polymer mixture was distributed by means of a
product line to twelve spinning positions, where each position
contained six spinning packets, and where the mean residence time
of the second polymer mixture from the time of exiting from the
static mixture to the entry into the spinning packet was five
minutes. Each spinning unit contained a round nozzle with 34 holes
having a diameter of 0.25 mm and a length of twice the diameter.
The spinning unit contained a spinning filter unit above the nozzle
plate consisting of a steel sand packing at a height of 30 mm with
a particle size of 0.5-0.85 mm, as well as a mesh fabric of 40
.mu.m and a non-woven steel filter having a pore diameter of 20
.mu.m. The diameter of the spinning filter unit was 85 mm. The
residence time of the melt in the filter unit was approximately 1.5
min. The heating of the spinning packet was set at 290.degree. C.
The surface of the spinning nozzle was 30 mm above the limit of the
heating box. At the time of the passage of the melt mixture, the
nozzle pressure established was 150 bar. The mean residence time of
the polymer mixture of polyester and additive melt from the
extruder outlet to the outlet from the spinning packet was
approximately ten minutes.
[0180] The melt-fluid filaments extruded from the nozzle holes were
cooled by means of blown air flowing horizontally with respect to
the filament direction at a speed of 0.55 m/sec and at a
temperature of 18.degree. C. and bundled at a distance of 1250 mm
from the nozzle plate in an oiling stone to form a yarn, which was
coated with spinning preparation.
[0181] An S-shaped looped roller pair pulled off the filament at a
speed of 5000 m/min, where the spinning traction ratio was set at
141.
[0182] Between the rollers, a fluidization nozzle that was closed
during normal filament direction was installed, which applied a
fluidization knot number of 13 knots/m to the filament at an air
pressure of 4.5 bar. The inlet tension at the inlet of the
fluidization nozzle was set at 0.16 g/den.
[0183] In each case, six filaments of one spinning position were
spooled onto a spooler to form spool packets, where the spooling
speed of 4985 m/min was chosen in such a manner that the filament
tension was 0.1 g/den before the spooling. The preoriented (POY)
filaments obtained were characterized by a titer of 126 den, an
elongation at break of 116%, and a rupture strength of 2.4
g/den.
[0184] During the production period of seven days, the rupture rate
during the operation of the spinning system was on average 0.75
rupture per ton of polymer mixture processed.
[0185] The POYs obtained were stretch textured at a speed of 900
m/min using a texturing machine of the type FK6 manufactured by
Barmag AG/Germany. The stretch ratio was 1.77, and the heating
temperatures 1 and 2 were 210 and 170.degree. C., respectively. The
average rupture rate was 21 ruptures per ton of textured yarn. The
textured yarn had a titer of 74 den, a rupture strength of 4.5
g/den, an elongation at break of 18.3%, and was characterized by
good dye-uptake homogeneity.
Example According to the Invention
[0186] The spinning system described in the comparative example was
used again with the same passage and spinning conditions. In the
example according to the invention, an additive was also used
consisting of 89.2 wt % methyl methacrylate, 8.8 wt % styrene and 2
wt % N-cyclohexylmaleinimide, where the terpolymer had a viscosity
value VZ of approximately 101 cm.sup.3/g. In contrast to the
comparative example above, MMA/styrene/N-cyclohexylmaleinimide
additive was used that had been obtained by a multiple initiation
as follows:
[0187] a mixture of 525 kg of completely desalted water, 0.071 kg
of KHSO.sub.4, and 13 kg of a 13% aqueous solution of a polyacrylic
acid was heated to 40.degree. C. in a 1000-L polymerization vessel
with heating/cooling jacket equipped with stirrer, reflux cooler,
and thermometer. Under stirring, 525 kg of a mixture of 88.68 parts
by weight of methyl methacrylate (MMA), 8.75 parts by weight of
styrene, 1.99 parts by weight of N-cyclohexylmaleinimide, 0.14 part
by weight of thioglycolic acid 2-ethylhexyl ester, 0.09 part by
weight of t-dodecylmercaptan, 0.05 part by weight of stearic acid,
0.2 part by weight of dilauroyl peroxide, and 0.1 part by weight of
tert-amylperoxy-2-ethylhexanoate was then added. The preparation
was polymerized for 115 min at 80.degree. C. and for 60 min at
98.degree. C. and then cooled to room temperature. The polymer
beads were then removed by filtration, thoroughly washed with
completely desalted water, and dried in a fluidized bed dryer at
80.degree. C. The dried polymer beads were then mixed with 0.1 part
by weight of a spray dried MMA/styrene emulsion polymer (whose
synthesis was described above in the comparative example) and mixed
for approximately five minutes in the fluidized bed dryer.
[0188] The product obtained consisted of 513 kg of polymer beads
with a viscosity value according to DIN 7745 of 101 cm.sup.3/g, a
residual methyl methacrylate content of 0.22 wt %, and a mean
particle diameter of 0.75 mm. The residual styrene content was
below the detection limit of 0.05 wt %. The residual
N-cyclohexylmaleinimide content was less than the detection limit
of 0.1 wt %.
[0189] In comparison to the additive obtained in the comparative
example, the additive from the example according to the invention
had a considerably lower residual monomer content while having a
similar bead size and treatment with MMA/styrene emulsion polymer
in the fluidized bed dryer.
[0190] The additive was added in the amount of 0.77 wt % with
reference to the total quantity of polymer mixture introduced into
the spinning system, and the polymer mixture was spun analogously
to the comparative example.
[0191] POY filaments were again produced during a production period
of seven days, characterized by a titer of 126 den, an elongation
at break of 117%, and a rupture strength of 2.4 g/den. The average
rupture rate during operation of the spinning system here was 0.35
rupture per ton of polymer mixture processed.
[0192] The POYs were stretch textured analogously to the
comparative example at a speed of 900 m/min. The average rupture
rate was 18 ruptures per ton of textured yarn. The textured yarn,
while having the same titer and the same rupture strength as the
textured yarn obtained in the comparative example, had an
elongation at break of 18.6% while having an equally good
dye-uptake homogeneity.
* * * * *