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
2001-12-11
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...
C524S157000, C524S166000, C524S305000
Reexamination Certificate
active
06329452
ABSTRACT:
This invention relates to polyurethane compositions, and relates in particular to elastic polyurethane fibres resulting therefrom, which contain a dialkyl sulphosuccinate as an additive and/or which are finished with a mixture comprising a polydialkylsiloxane, a dialkyl sulphosuccinate and optionally a mineral oil. As a result of this addition or of the preparation of the polyurethane composition or of the elastic polyurethane fibres with dialkyl sulphosuccinate, electrostatic charging of the polymer, such as that which occurs during the processing of warp-knitted fabric made of polyurethane fibres for example, is suppressed. In extreme cases, electrostatic charging can result in sparks flying due to electrical discharges.
The expression “fibre” which is used in the context of the description of the present invention includes staple fibres and continuous filaments which can be produced by spinning processes, the principles of which are known, such as the dry spinning process, the wet spinning process or the melt spinning process.
These spinning processes are described, for example, in Polyurethan-Elastomerfasern, by H. Gall and M. Kausch, in the Kunststoff-Handbuch 7, Polyurethanes, Editor: G. Oertel, Carl Hanser Verlag, Munich, Vienna, 1993, pages 679 to 694.
Elastic polyurethane fibres comprising long chain synthetic polymers, at least 85% of which are synthesised from segmented polyurethanes based on polyethers, polyesters and/or polycarbonates for example, are well known. Yarns made of fibres such as these are used for the production of sheet goods or woven textiles or substances which in turn are suitable for foundation garments, hosiery and sports clothing, such as swimwear or bathing trunks for example. The warp-knitting process is one form of processing polyurethane fibres to form sheet goods. A high rate of processing in the warp-knitting process can result in the twisting of the warp fibres, due to which the processing procedure is significantly impaired. This can ultimately result in the stoppage of machinery.
One cause of problems during the processing of warp-knitted fabrics is the electrostatic charging of the fibre material. In some cases, this can even result in sparks flying due to intense electric discharge phenomena. From a practical point of view, these problems during the processing of warp-knitted fabrics are unacceptable, since they necessitate an unwanted reduction in processing speed or a costly installation of spray bars on the processing machines in order to dissipate the electrical charge.
One solution to the problem of electrostatic charging during the processing of polyurethane fibres is described in Japanese Patent Application JP 9-49 167. This patent discloses finishing compositions (preparations) which contain a mixture of salts of alkanol-ammonium- and alkali metal-phosphoric acid esters as additives which are necessary for imparting antistatic properties to the fibres. The disadvantage of the mixture of salts of phosphoric acid esters which is described in this document is the limited solubility of these salts in the preparation oil, which consists of a mixture of polydimethylsiloxanes and mineral oils. Due to this, a special and technically expensive preparation technique is necessary for the deposition of the preparation on the polyurethane fibres, so as to be able to ensure uniform deposition of the preparation. Another disadvantage of this known preparation is the content of salts of phosphoric acid esters in the preparation, which can restrict the mode of operation of biologically operating sewage treatment plants when introduced into the production waste water. Due to this, large amounts of salt-containing waste material, which has to be disposed of separately, are formed during the further processing of polyurethane fibres in washing and dyeing processes, for example.
U.S. Pat. No. 32,96,063 describes the use of a preparation for the protection of polyurethane fibres from electrostatic charging, which consists of a mixture of low-viscosity polydimethylsiloxanes or mineral oils and polyamylsiloxane. However, the preparation system described has the disadvantage that the protection from electrostatic charging is not satisfactory.
U.S. Pat. Nos. 42,96,174 and 51,35,575 describe mixtures of polydimethylsiloxane, polyamylsiloxane and salts of fatty acids for the preparation of polyurethane fibres. However, the preparation systems described also have the disadvantage that the protection from electrostatic charging is not satisfactory.
A preparation system consisting of an aminopolysiloxane and a dialkyl sulpho-succinate is known from EP 493 766 A1. This water-soluble mixture is claimed to protect acrylic fibres from charging during the further processing thereof to form carbon fibres, and is completely decomposed on the oxidation and graphitisation of the acrylic fibres to form carbon fibres. However, the preparation system described has the disadvantage that the amino groups of the aminopolysiloxane can react with the polyurethane composition. This can result in the swelling of elastane fibres, for example, which has a disadvantageous effect on the processing properties of the fibres. Moreover, the removal of the preparation by washing which is necessary before the dyeing of an elastane fibre is made more difficult or is impossible. Uniform dyeing of the fibres is thereby made difficult or is even prevented. One serious disadvantage of the preparation system described is that aminopolysiloxanes can be toxic on inhalation. Accordingly, both the preparation of the fibres and further processing have to be carried out in particularly costly closed installations. For the further processing to form carbon fibres which is described in EP 493 766, this disadvantage is accepted for the production of the intermediate product.
The underlying object of the present invention is to provide a polyurethane fibre, the antistatic properties of which are improved compared with known polyurethane fibres. Improving the antistatic properties should result, during the processing of warp-knitted fabrics which are used for the production of foundation garments or swimwear, in the processing procedure not being impaired due to electrostatic charging.
This object is achieved according to the invention by adding an effective amount of a dialkyl sulphosuccinate, as a substance having an antistatic effect, to the polyurethane composition, and/or by depositing this substance in a suitable form as an external preparation on the elastic fibres.
The present invention relates to a polyurethane composition which exhibits improved antistatic behaviour, characterised in that it comprises
A) from 99.98 to 65% by weight, particularly 99.95 to 80% by weight, most preferably 99.9 to 85% by weight, of a polyurethane
B) from 0.02 to 15% by weight, particularly 0.05 to 5% by weight, most preferably 0.1 to 3% by weight, of a dialkyl sulphosuccinate corresponding to general formula (1)
wherein
R
1
and R
2
, independently of each other and identically or differently, represent hydrogen or an alkyl group comprising 1 to 30 carbon atoms, and preferably represent an alkyl group comprising 4 to 18 carbon atoms, and
M
+
is H
+
, Li
+
, Na
+
, K
+
or NH
4
+
, and
C) from 0 to 20% by weight, particularly 0 to 15% by weight, of additive substances.
Due to the improvement in the electrostatic behaviour of the polyurethane fibres, an improvement can be achieved in the processing of the fibres by, for example, the warp-knitted fabric procedure.
The present invention further relates to polyurethane fibres which are finished to render them antistatic, and which are based on a thermoplastic polyurethane or on a polymer comprising at least 85% by weight of segmented polyurethane containing from 0.02 to 15% by weight, particularly 0.05 to 5% by weight, most preferably 0.1 to 3% by weight of a dialkyl sulphosuccinate corresponding to general formula (1)
wherein
R
1
and R
2
, independently of each other and identically or differently, represent hydrogen or an alkyl gro
Bayer Aktiengesellschaft
Rajguru U.K
Seidleck James J.
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