Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-02-05
2002-05-21
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S127000, C524S270000, C524S322000
Reexamination Certificate
active
06391953
ABSTRACT:
The invention relates to a coating compound for fibers and to a process for the preparation thereof. The invention relates in particular to a preparation agent for elastanes based on a dispersion of fatty-acid metal salts and agglomeration inhibitor in polyorganosiloxanes and mineral oils. The preparations are produced by a precipitation process from which fine-particle and sedimentation-stable dispersions with a narrow particle size distribution are obtained and which are free from agglomerates. The coating compound reduces the electrical resistance of elastanes, no deposits of the coating compound on machine parts occurring during either the application or processing of the elastanes, even over a long period. Elastanes treated with the coating compound do not stick even after a long storage period, and remain processable.
The expression fiber used within the context of the present invention includes staple fibers and/or continuous filaments. The fibers e.g. elastanes may be prepared by spinning processes well known in principle such as the dry spinning process, the wet spinning process or the melt spinning process.
Such spinning processes are described, for example, in Polyurethan-Elastomerfaser, H. Gail and M. Kausch in Kunststoff-Handbuch 7, Polyurethane, Editor: G. Oertel, Carl Hanser Verlag Munich Vienna, 1993, page 679 to 694.
Elastanes, i.e. elastic polyurethane fibers of long-chain synthetic polymers, which are composed of at least 85% segmented polyurethanes based on e.g. polyethers, polyesters and/or polycarbonates, are well known. Yarns made of such fibers are used for the production of flat goods or fabrics or materials which, in turn, are suitable inter alia for the preparation of foundation garments, linen, stockings, sportswear and tapes. Polyurethane fibers have a substantial stickiness compared with other non-elastic textile fibers. Sticking of elastanes occurs particularly if elastanes are wound onto a bobbin or a sectional beam. Sticking of elastanes and the increased adhesion of the fibers to one another is observed particularly if the fibers were stored for a long period prior for further processing. This effect is intensified if the material is stored at elevated temperature.
If the polyurethane fibers are processed with, for example, polyamide fibers or cotton by means of a warp knitting or circular knitting process or by stocking machines, the stickiness or the adhesion of elastanes on bobbins or sectional beams may lead to considerable tensions in the fiber during unwinding which may lead to thread breakage and, in an extreme case, may mean that bobbins or sectional beams of such fibers can no longer be processed.
In practice, a reduction in the stickiness or adhesion of elastanes after storage, even at elevated temperature is sought by a fiber treatment directly after production of the fiber by applying special preparation oils to the fiber.
In U.S. Pat. No. 3,039,895, the use of mineral oils and metal soaps dispersed therein, preferably magnesium stearate, is recommended for reducing the adhesion or stickiness of elastanes. In patent application EP 704 571 and U.S. Pat. No. 4,296,174, the use of low-viscosity, linear and branched polysiloxanes with metal soaps dispersed therein is recommended for reducing the stickiness of elastanes, magnesium stearate likewise being preferred. A disadvantage of the preparations described, however, is that the metal soaps dispersed in the oil may lead to deposits in the preparation system or to blockages when polyurethane fibers are coated by, for example, roll, yam guide or spray methods. A consequence of this is, for example, the shortened operating time of the spinning machines and an increased expenditure for cleaning the spinning machines and the preparation system. A reliable, uniform preparation of the polyurethane fibers over a long period is thus not possible using the preparation agents mentioned.
The preparation of dispersions stabilised against sedimentation, composed of magnesium stearate in polyorganosiloxanes or mineral oils is described in U.S. Pat. No. 5,135,575. In the process described there, magnesium stearate is processed with organic solvents such as, e.g., isopropanol, chloroform, acetone or heptane to a paste, mixed with polyorganosiloxane or mineral oil and ground in a mill. A disadvantage of this method of preparation is that magnesium stearate is incorporated in the fine-particle form in the silicone oil by means of an elaborate grinding process. Moreover, the use of organic solvents entails the expensive recovery of the solvents, and there is also a risk of ignition or explosion of the solvent, depending on the nature of the solvent.
A preparation for reducing the adhesion of polyurethane fibers is described in the patent JP188 875. This is composed of a polydimethylsiloxane, a higher alcohol, the ethers thereof or a fatty acid ester composed of a fatty acid with at least 12 carbon atoms, a modified silicone and the metal salt of a fatty acid with at least eight carbon atoms. The disadvantage of the preparation mentioned, however, is similar to that of the other well known preparation described above. During application to polyurethane fibers, the dispersed metal soaps lead to deposits in the preparation system which may extend to blockages of preparation feed lines. In connection with this, the operating time of the spinning machines is reduced. The expenditure for cleaning the spinning machines and the preparation system is increased considerably. A reliable and uniform preparation of the polyurethane fibers over a long period is not achieved with such preparations.
The production of fine particles of fatty-acid metal salts in polydimethylsiloxane for the preparation is described in the patent JP 60 67 442 for reducing the adhesion of elastanes. Magnesium stearate or calcium oleate in a pressure-resistant vessel is dissolved in hexane or benzene at 140 or 130° C. and precipitated by rapid cooling at 10° C./min. The introduction of this dispersion into low-viscosity polydimethylsiloxane followed by distillation of hexane or benzene eventually leads to the ready to use preparation. A disadvantage of this preparation is the production process of the preparation which is laborious and expensive due to the distillation of hexane or benzene. Moreover, due to the use of organic solvents there is a risk of contaminating the environment or of ignition or explosion of the solvent.
The patent DD 251 578 describes the use of an aqueous suspension with finely divided magnesium and/or calcium stearate and optionally polydimethylsiloxane as a preparation for reducing the adhesion of elastanes produced by the wet spinning process. A disadvantage of this invention, however, is that a special drying of the fiber is required to remove the water from the dispersion after application to the polyurethane fiber. This entails an additional processing stage which makes the product more expensive.
The object of the invention is to provide a preparation for fibers, particularly for elastanes, which can be processed without difficulty during application by, for example, roll, yarn guide or spray methods, and which does not lead to deposits in the preparation system or on processing machines during the application and particularly the processing of elastanes with, for example, cotton or polyamide fibers to flat goods. The stickiness of elastanes should be reduced by the preparation and the processability of elastanes coated with the preparation should be guaranteed even after a long storage period. A further requirement to be met by preparations for elastanes which, if they contain solids, are in the form of dispersions, is to ensure a uniform application of the preparation and, combined with this, a uniform application of solids by stabilising the preparation against sedimentation. For this reason, a particular requirement to be met by a suitable solids-containing preparation is that not more than 20% of the solids in the preparation should settle out after a lengthy storage period of e.g. 10 days, and that it mu
Behrens Hans-Josef
Endesfelder Andreas
Hütte Stephan
Klinksiek Bernd
Wollweber Hans-Joachim
Bayer Aktiengesellschaft
Norris & McLaughlin & Marcus
Rajguru U. K.
Seidleck James J.
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