US2041798A - Production of artificial materials - Google Patents

Description

May 26, 1936. w. I. TAYLQR 2,041,798

PRODUCTION OF ARTIFICIAL MATERIALS Filed Dec. 12, 1931 Patented May 26, 1936 I g Y PRODUCTION OF ARTIFICIAL MATERIALS William Ivan Taylor, Spondon, near Derby, England, assignor to Celanese Corporation, a corporation of Delaware Application December 12, 1931, Serial No. 580,636 In Great Britain January 15, 1931 3 Claims. (01. 18-54) This invention relates to the production of artificial materials, and particularly to the production of heavy unitary filaments such as artificial horsehair, bristles, tapes, straws, ribbons or like materials, from a number of continuous artificial filaments of relatively small cross-section.

According to the invention a plurality of continuous artificial filaments while in a condition to adhere to one another are caused to pass through a die of appropriate shape, and are thereby caused to adhere and coalesce together to form a single filament of large cross-section. The shape of cross-section of the large filament will correspond closely to the shape of the die opening through which it has been passed, and may therefore be controlled to be of any desired shape, for example, perfectly round or oval, or polygonal, or even of cruciform or other shapes comprising re-entrant angles or curves. The die through which the filaments pass should be of an area not substantially exceeding the sum of the separate cross-sections of the filaments, in order that the filaments may be brought into necessarily close association with each other, to

give a substantially solid unitary product of uniform cross-section. By the use of dies, moreover, a good lustre is obtained. In order that the filaments may be in a condition to adhere to one another, they should be in a sticky state, either by reason of a content of material which is a solvent or softener for the substance of the filaments, or in the case of thermoplastic materials by reason of their temperature. For this purpose, the filaments may be heated, or solvent material may be applied to them or both, prior to passing them through the die.

The filaments to be united maybe treated with the solvent or softener individually and subsequently brought together, or they may be treated while associated as a twisted'o-r untwisted thread, or as a plurality of threads. The treatment may be carried out on the filaments while they are travelling at any convenient stage of their production. Thus for example, the filaments may be treated continuously with their production by the dry or evaporative method or by the wet or coagulation method, and while they are proceeding to a winding or twisting and winding device, or they may be treated in the course of any -bobbin-to-bobbin or similar Winding or twisting and winding operation.

The filaments while in a sticky state may be passed through a single die of the desired shape, or through twoor more dies in series. Where solvent is to be applied to the filaments it may be advisable to pass them through two dies in series, to maintain them in contact while they are soft. Thus, before the application of solvent, the filaments may be passed through a die of relatively large area in order to bring them into close association with each other, and, after receiving the solvent they may be passed through a die of appropriate size and profile to effect complete coalescence and shaping. The profile of the die through which the sticky filaments are caused to pass depends of course upon the cross-section desired in the resulting unitary filament. For this purpose the die may be of any shape. If it is desired to produce a thin ribbon-like or strawlike filament a die may be used which is open on one side, the thickness of the product being accurately determined by a die of three sides only. For filaments, of more solid cross-section, however, it is preferred to use a closed die, i. e. whose opening forms a closedfigure, so that the form of the product is controlled at every point round its surface. The position of the die along the path of the filaments should preferablybe adjustable along the length of the filaments to a point where the filaments are neither too soft, nor inclined to adhere to the die.

For the treatment of filaments continuously with their production it is preferred to use a die which is made in parts, to avoid the necessity of threading the end of the filament through the die. Two such forms of die are described in detail hereafter.

The solvent or softener may be applied by spraying or immersing the filaments or by passing them over rollers, rods, wicks, or other devices moistenedwith the substance or material. Such methods of application are particularly advantageous in applying liquid to the filaments in a controlled manner, in an amount not substantially exceeding that necessary to produce the coalescence desired. The solvent or softener may also be used in the form of vapour through which the filaments are passed. Further, when the treatment is carried out continuouslywith their production the filaments may be subjected to the coalescing treatment according to the invention while they are in a sticky or tacky condition by reason of residual solvent. In this case, substances may be added to the spinning, solution to maintain the filaments sticky or tacky for a sufficiently long period. For example, vinyl acetate may be added to solutions of cellulose acetate or other organic derivatives of cellulose in solvents such as acetone. Heat may also be employed in bringing thermoplastic filaments to a sticky or tacky condition, as by passing the filaments round heated rollers. In this Way, the requisite softness may be imparted to the filaments by the use of heat alone, though heating may be used to augment the softness of the filaments due to residual or applied solvent or softening material. Thus for example the die through which the softened filaments are passed may itself, particularly if of massive construction, be heated to augment the softness of the filaments. Any undesirable stickiness in the products may be removed by treating them with suitable substances, such as lubricants at any desired stage in the process, e. g., before entering the last die, and before winding.

The filaments before or after passing through the die may be stretched as described in U. S. application S. No. 506,637 filed 5th January, 1931, as, for example, by passing the filaments successively round a pair of rollers rotating with different peripheral speeds. Stretch may be applied to the filaments in this manner prior to passing them through the die, in order to give a preliminary coalescence of the filaments, which are then completely coalesced or given an improved surface or lustre by the action of the die. After stretching and before reaching the die, the filaments may be further softened. The stretchlng rollers may alternatively be placed one before and one behind the die so that stretching takes place while the filaments are actually passing through the die.

If desired, the filaments may already be in a state of union with each other when they pass through the die which gives them their final cross-section. Thus, instead of causing separate filaments, or filaments simply associated as a twisted or untwisted thread, to unite, material may be employed which has sufficient bulk to make a product of desired cross-section when passed through the die. For example, the filaments to be treated according to the invention may have previously been passed through a die while sticky or tacky so as to cause them to coalesce. In one way of carrying out the invention, the filaments may be passed through the two dies in turn as a continuous operation.

The invention is particularly applicable to the treatment of artificial filaments having a basis of cellulose acetate or other cellulose derivatives, whether produced by the dry or evaporative method or by the Wet or coagulation method, and whether during the course of such production or subsequently thereto. Examples of other cellulose derivatives which may form the basis of the filaments are cellulose esters, e. g. cellulose formate, propionate, and butyrate, and nitrocellulose; cellulose ethers, e. g. methyl, ethyl, and benzyl cellulose; and the condensation products of cellulose and glycols and other polyhydric alcohols. Other types of artificial filaments may likewise be treated, either while they are capable of adhering to each other during their production or by the use of appropriate softening materials.

Solvents, suitable for use with filaments of cellulose acetate or other organic derivative of cellulose are low boiling solvents such as acetone, (commercially pure, or mixed with Water), ethylene dichloride and ethyl or methyl alcohol, dichlorethylene and ethyl or methyl alcohol etc., medium or high boiling solvents or plastifiers such as diacetin, triacetin, ethyl lactate, diacetone alcohol (alone or mixed with water or alcohol), dibutyl tartrate or tricresyl phosphate,

and mixtures thereof. The use of high boiling solvents or plastifiers imparts increased pliability to the product. When a volatile solvent such as acetone is employed, means may be employed to assist its evaporation from the filaments after the pressure has been applied, and, if desired,- such means may be associated with an apparatus for the recovery of the solvent.

For the removal and recovery of volatile solvents, the filaments, after being united together may be passed through a heated chamber, prior to winding or otherwise collecting the product. The chamber may be heated by such means for example as hot air, or steam jacketing, the solvent-laden gases being removed from the chamber, and, if desired, passed to a solvent recovery plant. Such solvents or softeners as are not removed by evaporation may if necessary be removed by any suitable operation, such as washing, or, and in the case of high boiling solvents or plastifiers preferably, may be allowed to remain in the products.

If desired, dyes or other colouring matter may be applied to the filaments which are to be united and coalesced. For example, the solvent or softener may have incorporated therein a dye, or metallic or other coloured powder which is thus applied to the filaments simultaneously with the solvent or softener. Further, striped effects may be produced by uniting coloured filaments or by introducing coloured or uncoloured filaments, yarns, or threads of the same or other material into the number of filaments to be united. For example, filaments of reconstituted cellulose such as viscose may be associated with filaments of cellulose acetate to give a product capable of receiving cross-dyed effects. Fine metallic wires or ribbons, such as tinsel, may also be incorporated in the product.

The filaments, ribbons, bristles, tapes, straw or other product may be wound or otherwise collected after treatment. They may be woven or otherwise formed into fabrics or articles, and are capable of wide use, for example, in millinery and as insulation for electrical purposes.

Several methods of carrying the invention into effect will now be described with reference to the accompanying drawing in which Fig. 1 is a diagrammatic elevation of one form of apparatus, Figs. 2 and 3 showing a detail of this apparatus;

Fig. 4 shows forms of cross-section which may be adopted in the dies;

Fig. 5 is an elevation of a further form of apparatus, Figs. 6 and '7 showing a detail of the apparatus;

Figs. 8 and 9 show details of one form of die, and Figs. 10, 11 and 12 of another form of die; and

Fig. 13 is another view of a wick device shown in Fig. 5.

Referring to Fig. 1, the desired number of filamentous threads I 5 required to make up the total denier of the finished product are taken from bobbins l6 provided with braking devices I! adapted to maintain the threads under tension. The threads are associated together at a guide l8 and passed through a die l9 which arranges them in a compact manner. The threads then pass over a wick 20 supplied with solvent from a container 2| and are then led through a second die 22 having the cross-section required in the finished product.

The filaments having been softened by the applied solvent, and caused to coalesce and assume the required cross-section by the die 22, the resultant product is passed through a drying chamber 23 in which the solvent used for softening the filaments is caused to evaporate from the product. The filaments are pulled through the several devices by means of a feed roller 24, after leaving which the finished product is wound on a bobbin 25, which is preferably frictionally driven, as by means of a drum 26.

In order to facilitate passing the threads through the dies the hole 21 in the die is preferably tapered as shown in Figs. 2 and 3. The die may be so shaped as to form large filaments or the like of any desired cross-section, but it is particularly suited for forming unitary products of compact-section, such as full-round, or oval or cruciform as shown in Fig. 4.

Softening of the filaments at starting up is preferably effected only after threading of the second die 22, and after the filaments have been led on to the bobbin 25.

Fig. illustrates the use of dies in connection with filaments 28 proceeding direct from a dryspinning cell 29. These filaments, after being associated by means of a guide 3!) and a die 3|, are led for softening through a wick device 32 and then over an open die 33, which is shown in greater detail in Figs. 6 and 7. The die shown has an opening 34 of rectangular shape and is adapted for the production of a straw-like product having a width which is determined by the width of the opening. In order to control accurately the width and cross-section of the flattened product, the opening 34 is preferably formed with a sharp edge 35 facing the filaments, as indicated in Fig. '7. The filaments are drawn from the spinning cell 29 and through the several devices of the apparatus by means of a feed roller 36 and the finished product is collected on the reel 31.

An open die of this sort is more particularly adapted for the production of fiat, straw-like materials of relatively little thickness when control of width is of primary importance, it being found that the constraint of the die on three sides of the cross-section suffices to give the product a substantially uniform cross-section.

While an open die such as 33 presents no difliculties when dealing with rapidly produced filaments such as are formed in the dry-spinning operation, the threading of a closed die cannot readily be effected. When products requiring the use of a closed die are to be made continuously with the production of their constituent filaments, it is preferred to use a die which is made in parts and which can be closed about the filaments while they are proceeding to the collecting device. One such device is shown in Figs. 8 and 9 and consists of two plates 38, 39 provided with notches 40, 4| whose apices are adapted to register with each other when the plates are assembled together. The filaments are thus led over the notch 40 and the plate 39 is then laid against the plate 38 so that the filaments also enter the notch 4|. By suitably assembling the two plates together, as by means of slots 42 in the plate 39 which engage pins 43 of the plate 38, the apices of the slots 40, 4| can be brought together to form a complete die of a cross-section determined by the form of the apices. The two plates are secured together in operative position by means of wing nuts 44.

Another form of die made in two parts is 5 shown in Figs. -12, the die proper being constituted by two tapered grooves 45, 46 in blocks 41, 48. The block 48 is provided with a projection 49 adapted to enter a recess 5|) in the block 41. After the filaments have been caused to pass 10 along the groove 45 of the block 41, the block 48 is laid on to the block 4'! as shown in Fig. 11, the filaments also being caused to enter the groove 46. By sliding the block 48 along the recess 50 the narrow ends of the grooves 45, 46 are brought close together as shown in Fig. 12 to complete the aperture of the die.

Fig. 13 shows in greater detail the wick device 32 employed in Fig. 5. This device, which enables the filaments to be uniformly treated with solvent, comprises a pair of blocks 5| mounted on the upper ends of two pairs of scissor-like levers 52 pivoted at 53 on brackets 54 mounted on a liquid container 55. The wicks 56 are secured to the blocks and depend into the container 55. Weights 51 are applied to the lower arms of the levers 52 so as to cause the wicks 56 to be pressed together on to the filaments 28 passing between the wicks.

What I claim and desire to secure by Letters Patent is:-

1. Process for the production of artificial horsehair, ribbons and the like, comprising passing an assembly of artificial filaments, the material of which is in a set but superficially softened condition, through a die, having an opening of different cross-sectional shape than that of the assembly, which forms the assembly into a product whose cross-sectional shape corresponds to that of the die opening and whose cross-sectional area is substantially the same as that of the assembly.

2. Process for the production of artificial horsehair, ribbons and the like, comprising passing an assembly of artificial filaments containing cellulose acetate, the material of which is in a set but superficially softened condition, through a die, having an opening of different cross-sectional shape than that of the assembly, which forms the assembly into a product whose crosssectional shape corresponds to that of the die opening and whose cross-sectional area is substantially the same as that of the assembly.

3. Process for the production of artificial horsehair, ribbons and the like, comprising forming an assembly of filaments containing cellulose acetate by passing the filaments through a die adapted to compact said filaments, softening said assembly of filaments and passing said assembly of filaments, while the material thereof is in a set but superficially softened condition, 60 through a die, having an opening of different cross-sectional shape than that of the assembly, which forms the assembly into a product whose cross-sectional shape corresponds to that of the second die opening and whose cross-sectional area is substantially the same as that of the assembly.

WILLIAM IVAN TAYLOR.

CERTIFICATE or cssscrion,

i atent Rio. e o- 1,798;

may .26, 1956.

WILLIAM IVAN TAYLOR.

It is hereby certified that the name of the assignee in the above numbered. patent was erroneously described and specified as "Celanese Corporation whereas said name should have been described and specified as Celanese Corporation of America, a ooporation of Delaware, as shown by the records of assignments in this office; and that the saici Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of July, A. D. 1936..

o a Henry venjrsdale v l U Acting Commissioner of Patents.

Images