US2198927A - Process for the fabrication of extrusion products from polymerization products of diene hydrocarbons - Google Patents

Description

April 30, 1940- H. I. WATERMAN El AL 8,9 7

PROCESS FOR THE FABRICATION 0F EXTRUSION PRODUCTS FROM POLYMERIZATIQN PRODUCTS 0F DIENE HYDROCARBONS Filed March 19', 1938 lnvenl'ors: Hein lsrozl Waterman Willem Leander-f Johannes d2 Nle Patented A 30,1940

BONS

to Shell Development mm. San Francisco, calls, a corporation of Delaware Application M is. ms. Serial 80.19MB

- m the'Netheriands Hay s, 1m

The present-invention relat to a new "and improved process for the fabrication, from polymerizationproducts of diene hydrocarbons. "of

j continuous, non-supported objects of small cross- 151 section such as'films, ribbons, threads, fibers,

, could be made from the polymerition products of diene hydrocarbons, such as butadiene and isoprene. The products fabricated, however,

have until recently been of such inferior quality that little importance was ascribed to the process for their fabrication. The threads were thick,

dark-colored, non-uniform, either brittle and hard or low-melting and easily extensible, of very low tensile strength and were very dimcuit to fabricate. Recently, however, improvements have been made which have-eliminated many of these faults. These improvements may be divided into two categories, namely, improvements f concerning the preparation of the spinning solution and improvements concerning the iabricaan "tion or the filament.

' -'While' the eflect or various co-polymers, im-. purities, solvents, catalysts, and methods of polymerlzing have far-reaching uence on the properties of the finished product. it has been .35 found that its properties are no less dependent upon variations in the methods for forming and treating the'viscous thread.

"The accepted methods for. the fabrication of 7 threads from polymerized diene hydrocarbons in consistessentially in-spinning the molten'polymer, or solution thereof, into a long, vertical, .heated tube wherein-"the solvent, if present, is vaporized and the polymer filament given sumcient heat treatment to render it strong enough is .{or subsequent handling and further hardening.

This method ofiabricating has-certain inherent defects which result in a thread oiimpaired strength, color, etc. The method requires high spinning speeds in order toavoid the continual an breaking oi the thread at the orifice. This is due to'the fact that 'the'polymer solution at the spinning'nozzle. 'even'when no solvent is present, is

'. in reality nothing more than -a thick; viscous liquid in the form of a thread which cannot as support vits own weight when stationary. In

thread near the spinning orifice towithatand iubsequent-processing, this thread must'imdergo considerable hardening. Since the fast'spinning rate necessarily employed allows 1 only a very short time, this necessitates drastic conditions of hardening. such as temperatures ranging from 2000. to over 500 0., depending. upon the diameter of the thread. Such drastic conditions not only tend to discolor the thread. but. tend to 'overharden the outside'portion of 10 the thread which in turn impairs the strength and-by hindering the diiiusion of the solventcon- Win the center of the thread makes a longer or more drastic final hardening treatment necessary, and may give a false flexibility. A "false flexibility due to small amounts of volatile constituents remaining in the center of the filament, results in an early aging and em-brittlem'ent of 'the filament caused by the slow diffusion of the plasticiaing solvent. This difilculty cannot be 20 overcome by increasing the length of the heated tube, since this increases the weight of the, suspended thread which in turn requires a-greater spinning speed in order to avoid parting-oi the Further, in 15 order that the thread shall have suflicient strength atthe spinning nozzle, it is' customary to spin concentrated solutions of the polymer. This has the disadvantages of requiring high spinning pressures and also, since there is less shrinkage, of requiring orifices of smaller diam 'eter to produce-a thread oi as given denier. The" small orifices, in turn, require higher spinning pressures, clog more easily and are more costly. The method is furthermore not applicable to the production of objects of other than circular crosssection, since flat objects tend to curL-th'icken and warp under the severe conditions. v

It is an object 01' the present invention to 7 provide a method for the production of threads '40 from the polymerization products of diene hydrocarbons. which allows the threads to be spun from dilute solutions of the, polymer. o

A further object of the invention is to provide a method for the production 0! threads from so the, polymerization productsoi diene hydrocar 'bons-which avoids such heat treatment as may cause discoloration and weakening of the threads. Still a further object-of the present invention is to provide a method for the production of sostronger threads from the polymerization prodnets of diene hydrocarbons.

v small cross-sectiomsuch as foils, ribbons, films,

, pie, the present threads are coagulated by diflu- 1 longer time.

etc., from the polymerization products of diene hydrocarbons.

It is also an object of the invention to provide a method which is economical and applicable on a commercial scale.

Other objects and advantages of the invention gill become apparent from the following descrip- These objects, we have found, may be realized by employing a suitable "wet spinning process, followed by a preliminary hardening process.

Although "wet spinning" methods have been employed for the production of other types of I synthetic threads, it could not easily be foreseen that such methods would be applicable to the production of the present threads, and, furthermore, are not without considerable modification. This is due to the inherently different-character- U istics of the present coagulated threads. Unlike the freshly coagulated viscose threads, for examspun dry according to accepted methods or spun wet according to the present invention, 4 only become strong and non-sticky after a suitable hardening treatment.

According to the method of the present invention, a suitable solution containing a polymerized diene hydrocarbon is spun vertically through an orifice into a suitable coagulating liquid, wherein a portion of the solvent difiuses from the thread into the liquid. The partially coagulated thread is then subjected to a further coagulating and preliminary hardening treatment.v 'ihis may be accomplished in either one of two ways. According to the first method, the partially cossulated thread is wound on suitable cylinders or drums rotating with the lower portion submerged in a coagulating liquid. 'After rotating for several hours, during which the thread is continually wet with the coagulating liquid, the thread is completely coagulate! and ready for the preliminary hardening treatment. This is accomplished by rewinding the thread from the cylinder onto reels and allowing to stand. for a few hours in air at room temperature and then for 24 hours at a temperature of about 32 C. The thread after this treatmentis non-sticky and ready for the final hardening treatment.

The'above method of completing the -8 tion and preliminary hardening, due to the fragility and stickiness ofthe partially coagulated thread, is beset with numerous mechanical diiliculties, and, moreover, is quite lengthy. For

method. According to this second method,jwe subject the partially or completely coagulated threadissuingfromthecoagulatingbathtoany finalcoaguiating treatment necessary and a prethese reasons we; prefer the second alternative amass? The final hardening may be accomplished by any one of the well-known methods. One suitable method consists in heating the threads for a suitable length of time in an oxygen-free atmosphere. During this treatment, we believe,

the polymerization reactions are caused to proceed to the-necessary extent to impart the desired qualities of strength and low extensibility.

The present invention is applicable to the fabrication of extrusion products from the polymerization products of any of the diene hydrocarbons capable of yielding products of suitable properties, such as, for example, the polymerization products of'butadiene, cyclopentadiene andbutadiene substituted in one or more positions by a hydrocarbon radical, for example, isoprene, piperylene, phenylbutadiene and the like.

The invention is, furthermore, applicable to the polymers of diene hydrocarbons when these are mixed with or polymerized with other types of ly erizable or partially. polymerized substances, for example, vinyl chloride, vinyl bromide, vinyl acetate, chloroprene, natural rubber,

cyclocautchouc, styrol, compounds of the structure s Br-C=CC =O R, a B4 Rr-C= =(|3-CEN hini.

strength. similarly, other materials may be used to impart special characteristics to the products.

The invention is not restricted as to the catalyst used, nor to the mode of polymerizing to form the polymer solution. Suitable catalysts applicable for the purpose include the alkali and alkali earth metals, their mixtures and alloys, peroxides such as benzoyl peroxide, ozcnides,

such as carvene ozonide, the halides .of amphoteric elements. such as such, PO15, etc., as also various other weaker acting polymerization catcatalysts, it is found that those of the first class,

namely the alkali and alkali earth metals and their mixtures and alloys, are very'efllcient for the polymerization of diene hydrocarbons and yield products of excellent properties. The other types of catalysts are known to produce polymerisation products of difierent characteristics, and are mainly recommended for the polymerization of diene hydrocarbons'wlth other substances. For example, butadiene and vinyl acctate are best polymerized together with benao peroxide. v I

The polymerization, if desired, may-be.carrled .out in the presence of any suitable solvent, or

part or all of the solvent may be added after the desired degree of polymerization has taken place.

mentioned the, aromatic hydrocarbons such as benzene, toluene, etc., cycloparafiin "hydroca'x bons, such as cyclohexane. etc., chlorinated h!- drocarbcns such as methylene chloride, carbon alysts such as 80:01:. EOa'POCla, etc. Of these 70 As examples of some applicable solvents may be as diethyl ether, dioxane, etc. The various sol- 'vents may, moreover, be used in conjunction and/or with or without the addition of permissiale proportions of non-solvents, such as ketones, alcohols, etc.

According to the present invention unusually dilute solutions of the polymers m y be employed. For example, we have found that solutions containing only of dissolved polymer may be conveniently spun according to thepresent method. This is advantageous since it obviates the concentrating of thepolymer solution, facilitates the removal of foreign matter, such as catalyst particles, dust dirt, lint, etc., facilitates the complete homogenizing of the polymer,

allows lower spinning pressures and allows thefabrication of threads of low denier number from inexpensive orifices. v

If desired, colored threads may be produced by incorporating a suitable dye prior to the spinning. A suitable dye should, however, be sumciently heat-stable to withstand the subsequent treatments of the thread.

The polymer solution is spun vertically into the coagulating liquid by a conventional spinning nozzle. Since the weight ofthe thread is practically neutralized by the buoyancy of the coagulator, it is not necessary to spin rapidly. The thickness of the thread, the character of the coagulating liquid and the length of path travelled in the coagulating liquid before the thread comes in contact with a solid surface are the factors determining the maximum spinning rate possible.

.A special embodiment of the process consists in spinning the polymer solutions into a vertically disposed leg of a V-shaped tube filled with a coagulating liquid, and pulling the coagulated thread from the inclined leg. In such an apparatus the rate of spinning is so regulated. that the thread is sufficiently coagulated to resist sticking upon passing under suitable guide-rolls v placed in the vertex of the V-shaped tube.

The function of the coagulator is to dissolve the solvent from the spunpolymer solution without dissolving the polymer, thus leaving the polymer thread sufficiently strong and non-sticky to be further processed. Consequently, we may use any-compound or solution capable of performing this simple function.- The coagulator may cdnsist essentially, therefore, of one or. more of such compounds as methyl alcohol, ethyl alcohol, 150- propyl alcohol, benzyl alcohol, acetone, methyl ethyl ketone. aceto-phenone, butyraldehyde, b'enzaldehyde, etc. Methyl alcohol, ethyl alcohol and acetone are inexpensive, readily available and, moreover, exceptionally fast acting coagulators, e. g., if benzene is used as a solvent.

The coagulator liquid, upon becoming sufficiently diluted with solvent extracted from the polymer solution, should be replaced by fresh coagulator liquid. This may be done between runs, but is more conveniently accomplished by continually adding fresh coagulator to the bath and continually withdrawing used-coagulator at the same rate. The flow of coagulatorthus in duced may be either concurrent orlcountercurrent to the movement of the thread.

The thread issuing from the coagulator liquid, although sufficiently coagulated to resist sticking upon coming in contact with a-surface wet with v the coagulator, usually is not coagulated at the center.

It is of very low tensile strength, very extensible and prone to become sticky upon drythread issuing from the coagulator is immediately conducted through a bath of glycerine held at about C. This treatment besides insurin! the loss of sticking properties and the complete coagulation of the thread, enhances the tensile strength and lowers the extensibility.

The appended drawing illustrates a suitable form of apparatus for executing the process of the invention. The polymer solution enters the spinning nozzle I and, in the form of the thread 2,.is spun vertically in the coagulating liquid 3 contained in the V-shaped tube 4. The'thread is directed around the vertex of. the V-shaped tube by means of the guide-rolls i and is passed up the inclined leg out of the coagulating liquid.

The coagulator liquid is fed continuously into ing treatment is to cause the decrease of thei sticking properties and to cause the hardening reactions taking place within the thread to proceed in a controlled manner to produce threads of maximum tensile strength, any heat stable liq uid which will not dissolve or attack-the thread.

may be used. One group of compounds which we have found both practical and efficient as bath liquids are the higher boiling organo hydroxy compounds such as, for example, primary or secondary hexyl,- heptyl, or octyl alcohol, glycols,. glycerine, etc. Lower boiling liquids, such as many of the substances suitable as coagulators, may, however, also be used. These lower boiling liquids, since they involve the use of pressure, are less practical for the continuoustreatment, but may find application in a discontinuous method of efiecting the preliminary hardening, such as, for instance, by autoclaving.

The thread may vary in physical properties, de-

pending uponthe time and temperature of the preliminary hardening treatment. Upon subjecting the thread to a prolonged preliminary hardening treatment, it is hardly possible to produce threads of sufficient strength, etc., to meet the.

usual requirements. It is, however, usually more convenient to effect the final strengthening of the thread by a conventional final hardening process, and this method generally gives a thread with good properties. Thus, we may effect a moderate degree of hardening according toour,

preliminary hardening treatment, and finally deconventional final hardening treatment.

.velop the maximum strength in the thread by a A special embodiment of our process. according to which the diflicuities which aregenerally en-' countered owing to the stickiness to which the coagulated thread tends, as soon as it is no longer surrounded by coagulating liquid, consists in that the solution of polymerized diene is. spun into a suitable coagulating liquid which is' a suitable temperature being, for example. about 140 C. The resulting coagulated thread, after leaving the hot coagulating liquid, does not or practically not possess the troublesome propertyof being sticky, and may immediately be subjected to the final hardening treatment, no intermediate final coagulating treatment of the thread being necessary.

this special embodiment the hot liquid bath may consist either of a suitable coagulating liq uid, e. g., ethyl alcohol, or of a mixture of a 0088- ulating liquid and of a liquid which removes the stickiness of the coagulated thread, such as glycerine.

The threads produced according to the method of our invention are free from discoloration due to overheating, are of the desired strength and low extensibility, and are suitable to be spun and woven by the conventional methods. The fabrics so produced, especially if interspun or interwoven with other filaments such as viscose silk, acetate silk, wool, etc., are textiles of general usefulness. Threads and fabrics composed entirely of the filaments of the present invention, due to their inertness to various chemicals, solvents, etc., and excellent physical properties, are especially adapted for many industrial uses such as, for instance, cable and other electrical apparatus insulation, chemical and solvent resistant clothing, hoods, bags, filter cloths, etc.

Various aspects of the invention are illustrated, but not limited, by the following description of,- the laboratory fabrication of a butadiene thread and spinning and weaving experiments therewith.

A polymerization product prepared by polymerization of butadiene of 95% purity in an autoclave at a temperature of 15-20 C. in the presence of about 5% metallic sodium was dissolved,

, after having been worked up. in benzene to a concentration of about and the solution obtained carefully filtered so as to remove undisthe thread to be stretched somewhat. This operation may also be carried out separately. The

spinning rate was adjusted at about 5-10 meters per minute, at which rate the thread was sufficiently coagulatedto prevent sticking as it passed under guide-rollers, placed in the vertex of the V-shaped tube. The alcohol was continuously renewed in the reverse direction to that I v in which the thread moved. The thread issuing gom the alcohol bath could be partially hardened in air and the decrease of the sticking propertiescould be obtained by passing it through hot glycerine. After being given a final hardens treatment these threads had a tensile strength of over 3 .kg./mm. and an extensibility of 5-10%. The thread of 107 denier was readily twined with one filament of viscous silk (175 denier) in a high speed twining machine; 1 Also four threads were intertwined to form a twined yarn which savedas a weft for two fabrics. In one fabric the warp consisted of wool-4 filaments of viscose silk-wool-5 filaments of ace.-

amass? spectively; the denier number of-.the weft was approximately 450. In weaving the iilament'the distribution ratio between the upper and under side was 3:1. -40% of this fabric consisted o butadiene polymer.

The second fabric was made with a colored warp consisting of red and yellow wool-one filament viscose silk-W0010ne filament acetate silkwool. 70% of this fabric consisted of butadiene polymer. While the present invention is especially concerned with the fabrication of threads from polymerization products of diene hydrocarbons. the invention is likewise applicable to the fabrication of other extrusion products of small cross-section. For example, ribbons, foils and the likemaybe made. which, since they are non-hygroscopic, unaflected by weather changes, exceptionally impervious to moisture, insoluble in common solvents, not affected by numerous acids and bases, etc., are useful for many purposes. We are aware that numerous details of the process may be varied through a wide range without departing from the principles of the invention, and we, therefore, do not desire our invention v to be limited to the specific embodiments herein disclosed except as defined in the appended claims construed as broadly as prior art.

We claim as our invention:

1. A process for the production of synthetic fibers which comprises forcing a solution of a polymerization product of butadiene containing less than 20% polymer through a suitable spin-L hing-nozzle vertically into a liquid consisting of at least a substantial proportion of a lower aliphatic alcohol, drawing the coagulated thread from said liquid at a rate exceeding the spinning rate, and immediately I passing the coagulated thread through a liquid bath consisting of at least a substantial proportion of an organo-hydroxy compound held at a hardening temperature above about 80 6 whereby a completely coagulated and at least partially hardened fiber is produced which may be further treated.

2. A process for the production of extrusion products which comprises forcing a solution of a polymerization product of a diene hydrocarbon through a suitable die, into a liquid which is readily miscible with the solvent used but does not appreciably dissolve the polymer and contacting the coagulated extrusionmroduct with a liquid which is at a hardening temperature above about 80 C. and which will not appreciably dissolve or attack the polymer. whereby a completely coagulated and at least partially hardened product is produced which may be further treated.

3. In a process for the production of an extrusion product, the-steps comprising forcing a solution of a polymerization product of a diene hydrocarbon through a suitable die, into a liquid which is readily miscible with the solvent used but does not appreciably dissolve the polymer and contacting the coagulated extrusion product with a liquid containing at least a substantial proportion of an organo-hvdroxy compound which liquid is at a hardening temperature above about 80 C.

4. ins process for the production of an extrusion product, the steps comprising forcing a solution of. a polymerization product of a butadiene through a suitable die, into a liquid which is permissible in view of the readily miscible with the solvent usd but does not appreciably dissolve the polymer and contacttate silk-wool.- The denier of the two artificial dug the coagulated extrusion product with a liquid silk warps were approximately 700 and 750 rewhich will not appreciably dissolve or attack the

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