US2084916A - Treatment of artificial silk - Google Patents

Description

Patented June 22, 1937 PATENTQOFFICE TREATMENT OF ARTIFICIAL SILK Jan Willem Lubberhuizen, Arnhem, Netherlands, assignor to American Enka Corporation, Enka, N. 0., a corporation of Delaware No Drawing. Application June 15, 1936, Serial 4 Claims.

The present invention relates to the treatment of packages of artificial silk threads and the like which have been manufactured according to the bobbin spinning process or the so-called centrifu- 5 gal or pot spinning process; and more particularly relates to a method for producing packages of threads having uniform physical and dyeing characteristics throughout all parts thereof.

In the manufacture of artificial silk threads a cellulosic solution is extruded through spinnerets having minute orifices therein and thence into a precipitating bath and coagulated to form threads. These threads are withdrawn from the said bath and collected in package form. The processing of the package includes several treating operations, such as washing, desulphurizing, bleaching, et cetera, whereafter the filaments or threads are dried.

The drying of the thread packages is an important operation and several different methods for so doing have been attempted in the past, but in each instance certain difficulties have arisen. One of the older methods of drying involved the tedious and expensive step of rewinding the thread and reeling same into skein form. Another more economical method of drying thread is in its original package form. However, disadvantages are apparent when drying in the original 30 form without any internal support thereof, in view of the tendency of the thread to contract more in the inner unsupported layers of the package than those on the outer portion of the package.

The inner layers are found to resist contraction 35 of the outer layers and these differences in contraction result in uneven dyeing or in differences in the rate of dye absorption in the finished package.

In an effort to promote free shrinkage and con- 40 traction throughout all parts of the thread package during the drying operation the mechanical deformation of the wet package has been at tempted to thereby loosen up the several layers of thread, otherwise prevented from contracting 45 freely. However, this step was not desirable owing to the sensitiveness of the wet filaments and therefore the introduction of further physical and dyeing irregularities in the thread. The probable origin of such irregularities was traced to the specific method of deforming the package which was effected by manual or mechanical pressure applied to the package at spaced points on the periphery thereof. This pressure tend- 55 ed to overstretch the thread at these points In Germany June 17, 1935 and prevented uniformity of contraction upon drying.

The present invention relates to an improved method of attaining uniform characteristics throughout all parts of an unsupported package 5 of artificial silk threads. The process concerns specifically the treatment of cakes of centrifucally spun silk and bobbin spun silk from which the internal support has been removed by any desirable means, These freshly spun packages 10 are preliminarily washed and dried in the normal manner, 1. e., while they are in circular formation and without mechanical strain thereupon. After drying, the package is deformed to provide completely loosened layers throughout all portions. In this condition the package is again moistened or rewetted and thereupon subjected to the other treating operations such as desulphurizing, bleaching, et cetera, and finally dried. These after treating steps may be combined 20 with the rewetting or may be entirely separate.

The characteristics of the finished package are greatly improved with respect to the uniformity of dyeing and in addition the ease with which the package may be processed owing to the increased permeability resulting from the loosened state of the threads first dried and subsequently deformed and processed. In deforming the dried package the characteristics of the threads are not altered as in the wet state because of the increased strength inherent in the same while the rewetting and redrying allow further contraction in the portions of the package which did not fully contract in the first drying. In the following of the present method the favorable results could not have been foreseen wherein artificial silk packages having been once dried and thereupon deformed, rewetted and redried would have more uniform properties than packages deformed in the wet state.

What is claimed is:

1. A process of producing artificial silk threads having uniform physical and dyeing characteristics which comprises forming a freshly spun unsupported package of threads, washing and drying the said unsupported package, deforming the same to loosen the thread layers therein, rewetting and redrying the package to permit uniform contraction throughout all parts of the spun thread package.

2. A process according to claim 1 in which the desulphurizing and bleaching operations are combined with the rewetting step prior to redrying.

3. A process according to claim 1 in which the desulphurizing and bleaching operation are conducted subsequent to the rewetting step and prior to redrying.

4. A process of producing artificial silk threads having uniform physical and dyeing characteristics which comprises forming a freshly spun unsupported circular package of threads, preliminarily washing and drying the package while retaining the same in a circular shape and without mechanical strain thereupon, deforming the dried package to loosen the thread layers throughout all portions thereof, rewetting the permeable package and thereafter desulphurizing, bleaching and redrying the package whereby uniformity of contraction throughout the package is efiected.

JAN WILLEM LUBBERHUIZEN.