Textiles: fluid treating apparatus – Machines – Liquid supply or vapor supply to liquid
Reexamination Certificate
2000-06-22
2004-09-28
Coe, Philip R. (Department: 1746)
Textiles: fluid treating apparatus
Machines
Liquid supply or vapor supply to liquid
Reexamination Certificate
active
06796151
ABSTRACT:
The present invention concerns a method of dyeing a textile substrate in at least one supercritical fluid, preferably for dyeing bobbins of yarn in supercritical carbon dioxide and a dyeing device for carrying out the method.
For several years, a method of dyeing textile substrates in supercritical fluids has been propagated, whereby the principles of dyeing in a supercritical fluid being described in German Patent Application No. 39 06 724 A.
German Patent Application No. 196 31 604 A describes a proposal for introducing the dyestuff required for dyeing into supercritical fluids, where the introduction of the dyestuff to be dissolved or dispersed in the respective supercritical fluid is accomplished by having the supercritical fluid loaded with the dyestuff flow through a special dye bath container filled with the total amount of the dyestuff and arranged in a bypass.
In general, the method of introducing the dyestuff into the supercritical fluid as described in German Patent Application No. 196 31 604 A functions satisfactorily. With certain dyestuffs, however, which have a tendency to sinter, for example, because of their low melting point when large quantities of dyestuff are placed in the dye batch vessel, the known method causes an additional expense in that inert particles must be added to the bulk dyestuff for this purpose or special dyestuff granules must be used.
The object of the present invention is to provide a method of the type described here and a suitable device which will permit rapid and especially simple introduction of the respective dyestuff into the supercritical fluid even when working with dyestuffs that tend to cake or sinter.
This object is achieved according to this invention by a method and by a device having the characterizing features set forth hereinbelow.
The method according to this invention for dyeing a textile substrate in at least one supercritical fluid, preferably for dyeing bobbins of yarn in supercritical carbon dioxide, like the known methods provides for the respective textile substrate to be arranged in an autoclave, where at least one supercritical fluid containing a dyestuff flows over (perfuse) and/or flows through (superfuses) it. First, the minimum of one solid, preferably powdered dyestuff is brought in contact with the supercritical fluid, forming a stable solution and/or dispersion of the dyestuff in the supercritical fluid. In deviation from the state of the art described above, however, the quantity of dyestuff required for dyeing is divided in the method according to this invention into a plurality of dyestuff partial quantities, and each partial quantity of dyestuff by itself remains in contact with the supercritical fluid until this partial quantity of dyestuff is dissolved or dispersed. As soon as this is the case, the next partial quantity of dyestuff is introduced into the supercritical fluid in the method according to this invention, with the procedure described above being repeated as often as necessary until the required total dyestuff quantity calculated in advance has been dissolved or dispersed in the supercritical fluid so that this dissolved or finely dispersed dyestuff can be absorbed by the respective textile material to be dyed.
Although at first glance, the method according to this invention may appear to be more complicated than that according to the state of the art, because with the method according to this invention the quantity of dyestuff to be dissolved or dispersed is first divided into a plurality of dyestuff partial quantities and then introduced separately and in succession into the supercritical fluid, it has surprisingly been found that the method according to this invention does not require any more time in comparison with the dyeing methods practiced in the past, especially with critical dyestuffs which have a tendency to agglomerate or to sinter. This is attributed to the fact that with the method according to this invention, a relatively large amount of supercritical fluid is available for relatively small partial quantities of dyestuff, so that the dissolving or dispersing of the dyestuff in the supercritical fluid are accelerated accordingly without resulting in any agglomeration or sintering of the respective partial quantity of dyestuff. Therefore, the method according to this invention also makes it possible to omit the addition of inert particles or preparing a certain size of dyestuff granules, as is the case with critical dyestuffs with the known method.
In addition, it has also proven to be an advantage of the method according to this invention that the composition of the partial quantity of dyestuff can be varied according to how the dyeing turns out, i.e., the shade and/or depth of color, so that by using the method according to this invention, nuancing of the dyeing is possible at any time, which is also impossible with the state of the art. Due to the fact that the partial quantity of dyestuff is introduced into the main stream of the supercritical fluid which is pumped in circulation with the method according to this invention, the dissolving or dispersing process of the partial quantity of dyestuff introduced in the respective case is greatly accelerated, which is not the case with the state of the art in particular when the dye batch vessel (color/trough) is arranged in a bypass to the main stream. Also, the partial quantity of dyestuff used in the method according to this invention does not cause any mentionable back pressure in comparison with the total quantity of dyestuff traditionally used, so that with the method according to this invention, the flow through this partial quantity of dyestuff can be much better, which in turn causes a great acceleration of the dissolving or dispersing behavior of the respective dyestuff used in the supercritical fluid.
By way of clarification, it should be pointed out that the term dyestuff used in the present patent application includes both an individual dyestuff as well as a dyestuff mixture consisting of two to twelve dyestuffs in particular. In addition, the term supercritical fluid includes in particular the fluids described in German Patent Application No. 39 06 724 A, but supercritical carbon dioxide is preferred in the method according to this invention. The method according to this invention preferably also includes such a method where bobbins of yarn, in particular bobbins of sewing yarn, are dyed with disperse dyes in supercritical carbon dioxide, and the disperse dyes used for this purpose include in particular conventional commercial disperse dyes such as those widely available commercially and used for aqueous dyeing of bobbins of polyester yarn. The yarn material preferably used in the method according to this invention includes or consists in particular of polyester, with polyethylene terephthalate (PET) yarn materials preferably also falling under this heading in addition to modified types of polyester.
A first embodiment of the process according to this invention provides for the quantity of dyestuff required for dyeing to be divided into 5 to 200, in particular 20 to 90 partial quantities of dyestuff, where it has surprisingly been found that such a division over the aforementioned partial quantities of dyestuff with a plurality of dyestuffs and dyestuff mixtures and over a broad range of shades and depths of color leads to excellent results, in particular so far as the required total quantity of dyestuff is dissolved or dispersed in the supercritical fluid within an extremely short period of time without occuring agglomerations or fused dyestuffs, resulting in especially even dyeings and good colorfastness.
In particular when each partial quantity of dyestuff is introduced into the stream of supercritical fluid in the method according to this invention in such a way that the total supercritical fluid circulated per unit of time is brought in contact with the partial quantity of dyestuff at least once, such a variant of the process has the effect that the total quantity of dyestuff is dissolved especially rapidly,
Eggers Rudolf
Truckenmuller Kurt
Amann & Soehne GmbH & Co.
Coe Philip R.
Greenberg & Traurig, LLP
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