US2234307A - Delustered artificial silk and the method of manufacturing same - Google Patents

Description

Patented Mar. 11, 1941 UNITED STATES DELUSTERED ARTIFICIAL SILKAND THE 'IWETHOD OF MANUFACTURING SAME Delaware No Drawing. Application March 8,1938, :SerialNo..194,599

6 Claims.

The present invention relates to an-improved method for reducing or eliminating'the lustero'f I artificial silk and to the improved product obtained thereby.

The normal artificial'silk fibers are usually as clear as glass and highly lustrous, both of which properties are undesirable for many purposes, such as garments of various kinds. For such purposes, the fiber is mademore or less opaque. This is accomplished by mixing inert oils of various kinds intothe spinning solution, such oils being dissolved out after the precipitation or solidification of the yarn, whereby'the'surface of the yarn becomes irregular with resulting reduction in luster. The luster has heretofore also-been reduced by adding to the 'spinning'solution a white filling material, suchras powdered asbestos, barium sulphate, ortitanium dioxide,

these added materials opaque.

'The addition of these known fillingimaterials has a number of disadvantages. In the :Ifirst placefthe filling material, especially in the-case of the heavy mineral substances, tends "to precipitate out in the vessels containing thespinning liquid, and the precipitated :material clogs the filter and the spinning or-extrusion nozzles. A perhaps more serious objection'arisesfrom 'the fact .that these additions represent dead "material in the-yarn, bein'g of an entirely different character from the cellulosic substance of the 'yarn'and incompatible therewith, andas azresult considerably reduce the strength of the yarn, particularly as no natural :bond -forms between the opaoifying ordelusteringagent and the yarn substance.

A further disadvantage which arises in .the case of mineral fillers,like bariumsulphate and titanium dioxide, is that they increaserthe average specific gravity of "the yarn, and'tend to -make it brittleand also harsh to the touch.

A still ifurther disadvantage of the use of mineral fillers or .of likematerial, is that such rendering the yarn material is not readily capable'iof tabsorbing dyes or other material, whereas itheietype of material contemplated for use by me as the fillersrea'dily absorbs dyes and coloring. The product will thus be capable of having imparted thereto a uniform color throughout the silk yarn and filler. The filler can thus be dyed before the dyeing of the silk, and therefore various color effects, combinations of colors in fillers and yarn, may be produced.

The present invention is based on the concept that it would be highly desirable to in- PATENT OFF-ICE 7 corporate in "the artificial silk a delustering-filling material having as nearly as possible the properties, aside from luster, of the yarn subthe artificial silk matrix butis at thersame time characterized by the feature that it :does-ariot swell in water although it is capable'of' absorbing water. 'I thus obtain a 'delusteredartificial:silk which retains its strength even in'wetting and shows 'no tendency to swell :by *reason' of the nature of the delustering agent. Thiscellulosic filleris of approximately the same 'specificgravity as the artificial silk, so that 'delustering'of the latter can be effected without fat the :same time loading it. Moreover, the :cellulosic filler is of approximatelythe same texturewand feel as the artificial silk, resembling the latter in these respects much more closely than the known inorganic fillers. Also,-the 'cellulosic material represents a very cheap filler, and moreover, shows a tendency to form some kind of combination or association with the substance of the artificial fiber, 'so that it does "not existin the finished fiber, at least no'wholly, as separate particles foreign to the substance of :the yarn and tending to weaken the-latter, but rather as a combined component which even acts to strengthenthe yarn.

I have found that a powdered cellulose prepared as described in .my "copending. application,

Ser. No. 187,965, filed January '31, 1938, .con-.

stitutes' a superior delustering agent for :artificial silk "because it possesses "to a'marked =degree the desirable properties "above referred to.

'Thispowdered cellulose, as described in said: ap-

plication, maybe prepared by subjecting-cellu- .lose to the action of'xaqueous formaldehyde in the presence of a strong acidiikernitrimacid;at

elevated temperatures, and with or "wit-houtsimultaneous drying, the product being ultimately dried if it has previously been subjected to the above-mentioned solution at the elevated temperatures but without drying. Cellulose so treated is capable of being easily ground to a fineness of 200 mesh and even finer without hydrating the cellulose. This ground cellulose is it! duced with known fillers.

dehyde and a small amount of acid, suchas abath consisting of 100 kg. of 40% formaldehyde,

/2 kg. of concentrated nitric acid and 50 kg. of

water, after which the excess liquidis withdrawn 15 by pressing, centrifuge, or otherwise, and the material then heated to a temperature which is preferably above 100 C. but not so high; as, to injure the material, and preferably with si;-j

multaneous drying. A temperature of the order 20 of 120 C. has been found to be highlysatisfactory. If the material is not dried during the heating (during which the reaction on the cellulose occurs) it is vthen dried and pulverized in any order, the reaction being continued until a 25 highly brittle product is obtained. This material can be pulverized to a condition of fineness resembling starch powder. l 1

The powdered cellulose employed by me does not tend to precipitate from the spinning solu- 30 tion during any stage in the manufacture of the yarn, being of approximately the same specific gravity as the artificial fiber, and therefore does not clogthefilters or the nozzles.

In the case of artificial yarn produced by an 35 alkaline process, as in the case of viscose yarn, there occurs a cementing of the cellulose filler particles with the spinning solution during the spinning, resulting in the production of a-yarn which is considerably stronger than one pro- With non-alkaline spinning solutions, the added cellulosic filling material absorbs the solvent by reason of its porosity and thereby becomes intimately incorporated with the cellulosic substance of the spin- 45 ning solution during the mixing, extrusion and precipitation or drying. In these non-alkaline processes, there is likewise obtained an artificial silk yarn having a pleasingly subdued luster.

The amount of cellulosic filling material to be 50 employed in any given case will depend largely upon the degree of delustering desired. Ordinarily, an amount of cellulosic ,filler equal to about 2 to 3% by weight of the artificial silk will be sufficient to reduce the high luster of 55 artificial silk to that of natural silk. The maximum size of the particles may vary within rather wide'limits, except they should not reach such a size as would be liable to clog the nozzles which are to be employed with the particular cellu- 5 losic composition. Cellulosic powders having a maximum particle size corresponding to about 200 mesh, or smaller, have been found to give very satisfactory results. In general, the particle size shouldbe 'of the order of that employed in 65 the case of the known mineral fillers like barium sulphate or titanium dioxide, for example, about 50 to100 microns.

The cellulosic filling-material may be mixed with the spinning solution in substantially the same way as the known filling materials now employed. Thus, the mixing may take place at room temperature. It may be desirable in some instances to keep the filling material in contact with the spinning solution fora somewhat longer period of time than is the case with mineral fillers, in order to enable the filler to become chemically associated with the spinning solution, but ordinarily, the time normally required for preparing. the mixture and extruding and precipitating or drying it, will be sufiicient to produce the desired effect.

Asalreadyfindicated, the cellulosic filler, according to'the" invention, may be employed with different kinds 'of artificial silks, including viscose, cellulose acetate, cellulose ether and cellulose nitrate silks. It will be obvious that the cellulosic filler can, if desired, be used, in conjunction with known fillers. Other variations may be resorted to within the scope of the appended claims without departing from the principles of the invention.

Also, the invention is obviously applicable 'to materials of any cellulosic form, whether artificialsilk, or cellulosic products, fibrous or other, for instance, in the form of ribbon, films, etc.

I claim: 1. An artificial silk material of reduced luster, having incorporated therein a ground cellulosic material which has been rendered brittle by heating'with aqueous formaldehyde and mineral acid followed by' drying and characterized by substantial freedom from swelling onwetting with water. i I Y 2. An artificial silk of reduced luster, having incorporated therein a powdered formaldehydeand acid-pretreated cellulose characterized by substantial freedom from swelling on wetting with water. 3. An artificial silk of reduced luster, having incorporated therein a comminuted cellulosic filler of a maximum particle size of the order of 50 to 100 microns and produced by heating cellulose with formaldehyde and a strong acid to a temperature of about 120 C. followed by drying and grinding.

4. An artificial silk of reduced luster, having incorporated therein about 2 to 3% of powdered cellulose'of a maximum particle size of about 100 microns and produced by heating cellulose with formaldehyde and nitric acid to a temperature of about 120 C. followed by drying and grinding in any order.

5; An acetate silk of reduced luster, having incorporated therein a powdered, formaldehydeand acid-pretreated cellulose characterized by substantial freedom from swelling on wetting with water.

6. Artificial silk fibers having suspended therein about 2m 3% of their weight of finely-powdered cellulose prepared by heating cellulose fibers with aqueous formaldehyde and a small proportion of mineral acid until a brittle product is obtained, followed by drying and grinding in any order. I

' JULIUS KANTOROWICZ.