Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2002-04-24
2003-12-16
Edwards, N. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S397000, C524S173000
Reexamination Certificate
active
06663959
ABSTRACT:
This invention relates to polyurethane-urea compositions and relates in particular to elastic polyurethane-urea fibres which result therefrom and which contain a dialkylsulphosuccinate as an additive which considerably increases the strength of the fibres.
The expression “fibre” which is used in the context of the description of the present invention comprises staple fibres and continuous filaments which can be produced by spinning processes which are known in principle, such as the dry spinning process, the wet spinning process or the melt spinning process.
These spinning processes are described, for example, in Polyurethan-Elastomer-fasem, by H. Gall and M. Kausch, in the Kunststoff-Handbuch 7, Polyurethanes, edited by G. Oertel, Carl Hanser Verlag Munich, Vienna 1993, pages 679 to 694.
Elastic polyurethane-urea fibres are well known which comprise long chain synthetic polymers, at least 85% of which are synthesised from segmented polyurethanes based on polyethers, polyesters and/or polycarbonates for example. Yams from fibres such as these are used for the production of sheet goods or woven fabrics or materials which in turn, amongst their other uses, are suitable for corsetry, hosiery and sports clothing such as bathing costumes or bathing trunks, for example.
Polyurethane-urea fibres exhibit outstanding elasticity and a considerable stretching capacity in combination with high restoring forces. Due to this outstanding combination of properties, they are widely used in the clothing sphere. In order to a achieve a higher productivity during the processing of polyurethane-urea fibres, processing is effected at high speed and under considerable drawing forces. A high tensile strength of polyurethane-urea fibres is necessary in order to enhance the reliability of processing and to achieve a further increase in productivity.
Various methods of increasing the strength of polyurethane-urea fibres are described in the literature.
Thus, for example, the strength of polyurethane-urea fibres can be improved if, instead of using ethylenediamine, which is generally used, as the sole chain lengthener for lengthening the chain of the prepolymer during the preparation of the polyurethane-urea solution, a second diamine is also used as a co-lengthener (see U.S. Pat. No. 5,616,676, EP-692 039 B2 for example). The polyurethane-urea fibres which are thus obtained do in fact exhibit an improved strength, but due to the impairment of the hard segments caused by the co-lengthener they have an inferior thermal resistance, which is disadvantageous for the processing of the fibres.
Moreover, the maximum tensile elongation is considerably reduced by the use of co-extenders. This can result in an increased frequency of fibre breakage when fibres such as these are processed with hard fibres, cotton fibres and other fibres, for example.
Japanese Patent publications (Kokoku) JP 44-22113 and JP 45-109956 describe an improvement in polyurethane-urea spinning solutions which is achieved by the reaction of the prepolymer with a small amount of a monofunctional alcohol (JP 44-22113) or amine (JP 45-109956) before chain lengthening is effected. The effect of these measures on the strength of the fibres is only very slight, however.
European Patent Application EP 0 843 032 A1 describes polyurethane-urea fibres which are obtained from spinning solutions and to which salts of certain alkylsulphonates or alkylsulphates comprising long chain alkyl radicals are added. However, this patent application does not go into the possible negative effect of adding this reagent on the thermal resistance of the polyurethane-urea fibres. A further disadvantage is that the addition of salts such as these can result in inhomogeneous spinning solutions, since these salts may be difficultly soluble in polyurethane spinning solutions. This necessitates considerable expenditure when incorporating additives such as these in the spinning solution.
German Patent DE 44 34 300 A1 describes elastane fibres which exhibit an improved thermofixing capacity and which contain alkali metal salts of carboxylic acids as additives. However, it follows from the examples described that the effect on the strength of the elastane fibres is only a slight one.
The unpublished German Patent Application which has the Application Number 19805130.1 describes elastane fibres on which dialkylsulphosuccinates or salts thereof are deposited with a conditioning agent in order to prevent electrostatic charging of these materials during processing. The possibility of including additives in the spinning composition is in fact mentioned. However, there are no examples of fibres comprising finely dispersed or dissolved dialkylsulphosuccinates or salts thereof. Nothing is stated in this Application with regard to improving the (fineness-related) strength of elastane fibres by the incorporation of dialkylsulphosuccinates or salts thereof.
The object of the present invention is to provide polyurethane-urea fibres which do not have the aforementioned disadvantages of known polyurethane-urea fibres and which exhibit an improved (fineness-related) strength whilst at the same time exhibiting good maximum tensile elongation and good thermal resistance.
It has been found that the strength of polyurethane-urea fibres can be considerably increased by adding the salt of a dialkylsulphosuccinate to the polyurethane-urea composition before spinning. Surprisingly, this addition does not have a negative effect on the thermal stability of elastane fibres. Moreover, it has been found that it is possible to incorporate the additive in the polyurethane-urea composition without considerable expenditure, since the solubility of the dialkylsulphosuccinate salts which are used is outstanding, and homogeneous solutions are obtained.
The present invention relates to a polyurethane-urea composition having improved mechanical properties, characterised in that it comprises
A) from 99.98 to 65% by weight, particularly from 99.95 to 80% by weight, most preferably from 99.9 to 85% by weight, of a polyurethane-urea polymer,
B) from 0.02 to 15% by weight, particularly from 0.05 to 5% by weight, most preferably from 0.1 to 3% by weight, of a dialkylsulphosuccinate corresponding to general formula (1)
wherein
R
1
and R
2
, independently of each other, are identical or different and represent an alkyl group comprising 5 to 10 carbon atoms, preferably an alkyl group comprising 8 carbon atoms, and are most preferably identical and represent 2-ethylhexyl radicals:
—CH
2
—CH(CH
2
—CH
3
)—CH
2
—CH
2
—CH
2
—CH
3
, and
M
+
is Li
+
, Na
+
, K
+
or NH
4
+
, preferably Na
+
,
and
C) from 0 to 20% by weight, particularly from 0 to 15% by weight, of additives.
By increasing the strength of the elastane fibres which contain the polyurethane-urea composition, the reliability of processing is increased and higher processing speeds become possible.
The polyurethane-urea compositions according to the invention contain segmented polyurethane-urea polymers. These polymers have a segmented structure, i.e. they contain “crystalline” and “amorphous” blocks (termed hard segments and soft segments, respectively).
In particular, the polyurethane-urea composition and the polyurethane-urea fibres can be produced from a linear homo- or copolymer which has a hydroxyl group at each end of its molecule and a molecular weight from 600 to 4000 g/mol, such as polyether diols, polyester diols, polyesteramide diols, polycarbonate diols, or from a mixture or from copolymers from this group. Furthermore, they are based on organic diisocyanates, with which the polymeric diols are reacted to form prepolymers comprising terminal isocyanate functions, and on diamines or mixtures of various diamines as chain lengtheners, with which the prepolymers which comprise terminal isocyanate functions are reacted to form high polymers.
Examples of organic diisocyanates include 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate and 4,4′-diphenylmethane diisocyanate. Examples of diamines inclu
Endesfelder Andreas
Gross Thomas
Hütte Stephan
Zweering Uwe
Bayer Aktiengesellschaft
Edwards N.
Norris & McLaughlin & Marcus
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