US2674025A - Polymeric filaments - Google Patents

Description

R. K. LADISCH POLYMERIC F'ILAMENTS F1led Aug 15 1949 pril 6, 1954 Patented Apr. 6, 1954 POLYMERIC FILAMENTS Rolf Karl Ladisch, Drexel Hill, Pa., assignor to Texiclon Corporation, poraton of Delaware Wilmington, Del., a cor- Application August 15, 1949, Serial No. 110,372 5 Claims. 01. 2ss2) (Granted under Title 35, U. S. Code (1952),

and Method of. Making the Same," Ser. No.

89,776 filed April 26, 1949. Filaments of this nvention may be matted together to form lightweight polymeric wools having improved characteristics or after twisting to make a yarn may be woven or knitted to make textile-like articles for many different uses.

In accordance with the present invention, filaments are formed by melt-spraying with the aid of a particular type of nozzle, to form filaments consisting essentially of polymerc tubular envelopes whose walls enclose cores which may be metallic or non-metallic, but which always constitute an important part of the mass of the filamnt, and may constitute a major part thereof. These cores may be of substantially uniform diameter throughout the length of the filament or may be of varying diameter, but in all 0bserved cases the walls of the filaments are free from the bulges or swellings which are disclose d in my Patent No. 2,571,457 dated October 16, 1951, and claimed in a divisional application now Patent No. 2612,679 dated October 7, 1952.

I am aware it is 01d as proposed in the Gardner Patent No. 1692,372, dated November 20, 1928, to

mix a salt oroXide of titanium with artificial silk prior to spinning to delusterize the filaments. Other p'ate'nts suggesting the addition of various salts' and pigments to filaments are the Tay1or Patent No. 2,034,008; the Helm et al.

Patent No. 2,233344; and the Spanagel Patent Filaments made pursuant to the invention may be of increased resilience and flexibility. The electrostatic, electro-conductive, magnetic and insulating qualities and the weight, feel,

curlness and other physical characteristics of filaments may be materially changed by following the invention, to eiect considerable improvements over filaments made from the pure polymer with or without a plasticizer.

In the accompanying drawings forming a part of this specification- Fig. 1 is a cross section through the preferred form of nozz1e used in forming the filaments;

Fig. 2 is a photomcrograph Of, a number of sec. 266) polyvinyl acetate filamerits combined with selenium;

Fig. 3 is a similar view of two cellulose propionate and tin fibers; and

Fig. 4 is a similar view showing in great1y en-" larged cross section two cellulose proponate filaments with so1id cores of metallic tin.

Referrihg to Fig. 1, the nozzle there shown is similar to the nozzle of German Patent No. 411,948 and corresponding U. S. Patent No. 1,811,637 issued to Carl Ladisch on June 23, 1931. It comprises a straight, central tube through which the hereinafter defined polymeric mixture flows, and a frusto-conical body H with conical internal wal1s 12 and an open end I 3. The end of tube |0 projects slght1y beyond the end of the frusto-conical body Il and is beveled as indicated at I4, the arrangement being such that the projecting beveled end of tube !0 does not in any way interfere with or defiect the flow of gas or vapor from the open end !3 of the conical body. A coupling I5 connects a gas discharge pipe [6 to the nozzle; usually the gas led to the nozzle will be air (or where a non-oxidizing gas must be used nitrogen, helium, producer gas, steam, etc. may be einployed), and such gas will be heated if the polymer is being melts ptayedij The gas enters the nozzle at its 1arger end through a port I'I, flowng under sperat mospheric pressure in a taigential path and then in a, spiral path with constantiy increasing velocity due to the decreasing diameter of the ndzzle, until finally it emerges as a spiral or whirling jet through the narrow annular space between the tube |0 and the open end I3 of the 1ozzle. Beyond the discharge orienng thgas r vapor continues to flow in a contracting spiral pathat constantly increasing veiocity until -it feaches a point (marked Vertex) which is the apex of the cone of the nternal walls 12 of the nozzle. At this point theoretically the velocity becomes infinite, but actually, due to air friction and other causes, is a finite figure of supersonic velocity, that is, higher than the velocity of sound in air at sea 1eve1. The formation of the fi1aments takes p1ace at and near this Vertex.

The term polymeric mixture, as used above and elsewhere in this specification, denotes a single polymer or copolymer with or without a plasticizer or a plurality of physically mixed polymers and copolymers. Obviously the polymeric mixture must be such that it will not deeompose under the conditions of heat and. pressure necessary to form the filaments. Among the polymers and copolymers which may be used are: polystyrene, polydichlorostyrene, polyamides of the nylon type, polyacrylonitrile, polymethacrylonitrile, polymethyl methacrylate, polymethyl acrylate, polyvinylidene chloride, polyvinyl chloride, polyvinyl carbazole, polyvinyl alcohol, polymeric glycol terephthalate, cellulose acetate, cellulose propionate, cellulose acetate butyrate, cellulose nitrate, ethyl cellulose, polyethylene, halogenated polyethylenes, polybutene, polyisobutylene, polyvinyl butyral, polyvinyl acetate and silicones. 'I'he term gas as usecl herein includes gaseous mixtures such as air, also vapors such as steam.

To mixtures or mixed melts of the selected polymeric mixture, powdered metal or other powdered solids are added prior to the feeding of said mixture to the nozzle. In lieu of powdered metals, molten metals of low melting point such as tin, metalloids, such as selenium, and low melting alloys such as soft selder, Roses metal, Newtons metal and Woods metal may be added to the molten polymerio mixture. Due primarily to the descrioed nozzle construction, relatively large amounts, as much as 80%, may be added without running the risk of clogging the nozzle. In other words, the described nozzle makes possible onthe first time the orming of filaments heavily laden with a metallic or metalloidal content, so that the filaments are more pronouncedly metallic (or metalloiclal) than polymeric.

When selenium (80% by weight) was added to polyvinyl acetate (Mowilith 30), it was in finely dividecl form, passing through a "250 mesh sieve. The nozzle temperature was 240 0., and the air pressure was 20 p. s. i. The. filaments ormed (Fig. 2) had a volume per weight ratio of 23 and. a diameter ranging from 1 to 18 microns. Fig. 2 (magnification 90X) is only an approximation of a few of the fibers forming a curly, tangled mass. The selenium was such a large part of the fiocrs that it impartecl a dark brown appearance and gave a rather harsh feel to them, besides making them quite brittle. Each fiber however consisted of a continuous thin tubular envelope surrounding the metalloidal core. The mixing of polyvinyl acetate with molten selenium in a 5--5O oy volume ratio results in a homogeneous viscous mixture at 240 C. which readily orrns filaments, again with the metalloid orming a core sheathed by the resin.

Fig. 3 shows the ends of two cellulose propionate fibers containng tin cores, enlargecl 85 times. Cellulose prcpicnate (Fortcel 28102) wa mixed. with tin powcler passing a. 325 mesh sieve, and the mixture was sprayed with a nozzle pressure of p. s. 1. and 3 p. s. i. pressure in the inner tube 19. Temperatures were 250 C. in the inner tube and. 2'70 C. for the compressed air. While part of the mixture left the Vertex in the form of plan polymeric fibers ancl separate tin pellets,

a considerable percentage of plastic fibers with tin cores were ormed. These tin cores were not continuous out varied in diameter (as Fig. 3 shows) as well as in length, some being as short as 2 mm., others beng measured as 50 mm. long. Fig. 4 (magnification 625X) shows in section solid tin cores which are a major part of the fibers, but in some sections the tin cores were so small that they could only be seen under the microscope, after dissolving away the polymeric envelope with methyl acetate. Microscopic examination failed to disclose a single tin fiber ree from a surrounding polymer.

Reference should be made to Patent No.

" 2,571,457 for a disclosure of apparatus suitable for practicing the method of the invention.

What I claim is:

1. Artificial filaments each consisting of a resincus polymeric mixture forming a generally tubular envelope with unbroken walls and nonuniorm thickness, and at least one core within said envelope forming a major fraction of the mass of the filament and being of a material selectedirom the group consisting of all metals, metalloids and alloys which are molten at the temperature of formation of the filaments and which form at least one solid core in the filaments, said core being of irregular but substantially circular cross section which varies non-uniformly in diameter along ts length and which also varies in its position within the envelope.

2. The invention according to claim 1 wherein the core is of selenium.

3. The inventon according to claim 1 wherein the core is of selenium which forms not more than about by weight or about 50% by volume of the filament.

4. The invention according to claim 1 wherein the core is composed of metallic tin.

5. The invention according to claim 4 wherein the tin is in dscontinuous cores distributecl along the length of the filament.

References Cited in the file of this patent 995,913 France Aug. 22, 1951

Claims (1)

1. ARTIFICIAL FILAMENTS EACH CONSISTING OF A RESINOUS POLYMERIC MIXTURE FORMING A GENERALLY TUBULAR ENVELOPE WITH UNBROKEN WALLS AND NONUNIFORM THICKNESS, AND AT LEAST ONE CORE WITHIN SAID ENVELOPE FORMING A MAJOR FRACTION OF THE MASS OF THE FILAMENTS AND BEING OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF ALL METALS, METALLOIDS AND ALLOYS WHICH ARE MOLTEN AT THE TEMPERATURE OF FORMATION OF THE FILAMENTS AND WHICH FORM AT LEAST ONE SOLID CORE IN THE FILAMENTS, SAID CORE BEING OF IRREGULAR BUT SUBSTANTIALLY CIR-

Images