US3126699A

US3126699A - Process for preparing

Info

Publication number: US3126699A
Authority: US
Priority date: 1962-10-09
Publication date: 1964-03-31
Anticipated expiration: 1981-03-31
Also published as: GB956749A; NL284369A

Description

March 1964 L. E. LEFEVRE ETAL 5 2 5 PROCESS FOR PREPARING FILAMENTARY ARTICLES 0F INVOLUTE CROSS SECTION Filed July 21, 1960 INVENTORS.

tloya'. efevre F/oyaE. Romesberg Gare/0'44. Hon

HGENT United States Patent 0."

3,126,699 PROCESS FOR PREPARING FILAMENTARY ARTICLES F INVOLUTE CROSS SECTION Lioyd E. Lefevre, Bay City, and Floyd E. Romesberg and Gerald M. Hart, Midland, Micln, assignors to The Dow Chemical (Iornpany, Midland, Mich, a corporation of Delaware Fiied July 21, 1960, Ser. No. 44,390 13 Claims. (Cl. 57-460) This invention relates to a process for preparing novel filamentary articles generally of cylindrical outline. More particularly, it relates to such a process for preparing such filamentary articles from fiat tapes or ribbons. Still further, the invention comprehends the novel filamentary articles so produced.

Cylindrical filaments are traditionally the most common structure finding use in the manufacture of woven and unwoven articles. However, the preparation of solid fibers and filaments of such structure involves complicated spinning procedures requiring delicate control. Also, when made from synthetic, resinous material, these filaments result in generally poor fabric stability, especially in the looser weaves. It is also commonplace to prepare hollow cylindrical filaments for special effects. The preparation of these hollow filaments is usually more complicated procedurally than the preparation of solid cylindrical filaments. Because of these known production problems, there has been continuous search for improvements in the processes for preparing fibers and filaments.

It is known that flat tapes and ribbons may be laterally rolled into a filamentary structure. For example, U.S. 2,335,190, issued November 23, 1943, to H. D. Minich, discloses a process wherein a flat tape of a resinous material, specifically rubber hydrochloride, is passed diagonally across a heated roll and caused to roll up into a generally cylindrical monofilament. This process is sub ject to several procedural disadvantages from a practical viewpoint. In that process the individual filaments tend to whip back and forth on the roll. To prevent contact of the filaments during rolling requires a wide separation between the individual filaments on the roll and, consequently, results in a limited productive capacity for that roll. In addition to that disadvantage, it has been found that reproducibility of the filaments prepared by that process is not always of acceptable standard for use in weaving closely woven fabrics. It would be desirable to have an improved process for preparing rolled monofilaments from flat tapes or ribbons which process would overcome the problems and disadvantages inherent in that patented technique.

Accordingly, it is the principal object of this invention to provide an improved process for preparing filamentary articles by laterally rolling a tape or ribbon.

It is a further object to provide such a process whereby a plurality of tapes while in the close proximity may be rolled simultaneously.

It is a still further object to provide such a process whereby positive rolling forces are brought to bear against the flat tape.

Another object is the provision of such a process utilizing organic, thermoplastic, resinous materials,

Yet another object is the provision of such a process whereby a fibrous or filamentary core material may be inserted into the center of the rolled filamentary article.

An associated object is the provision of novel, oriented filamentary articles of involute cross section.

The above and related objects are accomplished by means of the process comprising the passage of a continuous, coherent, unoriented ribbon of an organic, thermoplastic, resinous material in fiat, undistorted form into first guide means, removal of said ribbon from said ice first guide means so that a plane through the longitudinal axis of said ribbon and perpendicular to the width of said ribbon is at an acute angle to an extension of said plane of said ribbon entering said first guide means, the passage of said ribbon through a second guide means disposed parallel to said first guide means so as to divert or to deflect said ribbon into a direction of travel substantially parallel to and finitely displaced from said plane of said ribbon entering said first guide means while imparting a torque to said ribbon between said first and second guide means to cause said ribbon to roll into a filament of an involute cross section having the original edges of said ribbon essentially parallel to the longitudinal axis of the filament and while maintaining suflicient tension on said filament throughout the process to impart thereto orientation parallel to the longitudinal axis of said filament. The objects are further realized and attained with the oriented filamentary article so produced.

The tapes useful in the present method may be of any organic, thermoplastic, resinous material. As materials which may be advantageously used are the normally crystalline polymeric materials. These are the polymers which have a tendency to form crystallites or sites where small segments of a plurality of the polymer chains are oriented and held in position by secondary valence forces. This crystallite formation or crystallinity is usually visible when the polymers are examined by X-ray diffraction. Typical of the normally crystalline polymeric materials falling within the advantageous definition are the polymers and copolymers of at least 70 percent by weight of vinylidene chloride with the remainder composed of one or more monoethylenically unsaturated cotnonomers exemplary of which are vinyl chloride, vinyl acetate, vinyl propionate, acrylonitrile, alkyl and aralkyl acrylates having alkyl and aralkyl groups of up to about 8 carbon atoms, acrylic acid, acrylamide, vinyl alkyl ethers, vinyl alkyl ketones, acrolein, allyl esters and ethers, butadiene and chloroprene. Known ternary compositions also may be employed advantageously. Representative of such polymers are those composed of at least 70 percent by weight of vinylidene chloride with the remainder made up of, for example, acrolein and vinyl chloride, acrylic acid and acrylonitrile, alkyl acrylates and alkyl methacrylates, acrylonitrile and butadiene, acrylonitrile and itaconic acid, acrylonitrile and vinyl acetate, vinyl propi onate, or vinyl chloride, allyl esters or ethers and vinyl chloride, butadiene and vinyl acetate, vinyl propionate, or vinyl chloride and vinyl ethers and vinyl chloride. Quaternary polymers of similar monomeric composition will also be known. It has been found that the normally crystalline copolymers composed of from about 92 to 99 percent by weight of vinylidene chloride and correspondingly from 8 to 1 percent by Weight of acrylonitrile or of a lower alkyl acrylate have suitable polymerization characteristics, are well adapted for use in the manipulative steps in this process, and result in exceptionally useful filamentary articles. For these reasons these vinylidene chloride-acrylonitrile and vinylidene chloride-lower alkyl acrylate copolymers represent a preferred species for use herein. It should be understood, however, that the process is not limited to the treatment of normally crystalline polymers but that any non-elastic polymeric ma terial may be employed. There are manymaterials, such as polyvinyl chloride and the polystyrene, which are capable of forming continuous, coherent articles which are orientable but do not normally form crystallites. The polymeric materials, Whether crystalline or non-crystalline, may also include minor amountsof monomers, such as vinyl pyrrolidone, vinyl oxazolidinone, vinyl alkyl oxazolidinone, and the like, which are known to aid the dyereceptivity and other properties of fibrous materials. Likewise, polymers containing interpolymerized light and heat stabilizers may be used. Also operable in the present method are tapes of polymeric materials, such as the polyolefins, including, for example, polyethylene, polypropylene, copolymers of ethylene and propylene, and polyisobutylene. Equally useful in the method are the condensation polymers, such as the polyamides, including polyhexamethylene diadipamide, and the polyesters, including polyethyleneterephthalate. Also of utility are the tapes and ribbons of rubber hydrochloride, regenerated cellulose, synthetic cellulose derivatives, including cellulose esters, such as cellulose acetate, and cellulose ethers,

such as methyl cellulose and hydroxypropyl methyl cellulose. It should be apparent that any organic, thermoplastic, resinous material which is capable of being formed into a flat tape or ribbon will find utility in the present invention.

The useful tapes for the present method are flexible tapes usually of about 0.001 to 0.005 inch in thickness and of about 0.1 to 1 inch in width. The thickness and width to be used in any given instance will depend in large measure upon the end product desired and upon the shaping apparatus used. The above limits are those which would normally be associated with the manufac ture of fibers and filaments. When it is desired to make filamentary articles of greater size than, for example, about 0.3 inch diameter, it would usually be found desirable to employ other techniques since wide sections of tape, which are more accurately referred to as films, are not handled conveniently in the present procedural steps. However, it should be understood that the process is not limited precisely to the l-inch maximum, since useful articles may be prepared herefrom, although with less control of filament dimensions than with the narrower tapes.

The tapes or ribbons useful in the process may be prepared by known plastics fabrication techniques. For example, a dry formulation of the polymer may be thermally extruded directly into the tape or ribbon or into a film which is subsequently slit into the desired tape or ribbon. Another fabrication procedure involves the preparation of the tapes or ribbons directly or of a film which may be slit into the tapes or ribbons. In this procedure a latex is deposited on a substratum and then dried into the film or the film may be formed by the continuous, localized coagulation of the latex followed by drying and fusing. Other solutions and dispersions may be cast, precipitated, or coagulated into the tapes or ribbons or into films from which the ribbons may be slit. Such fabrication techniques are well known in the plastics art. It is only necessary for the present invention that the tape or ribbon be fused and unoriented. By fused it is means that the tape or ribbon is, in the sense accepted in the plastics field, completely homogeneous and integral as contrasted with the partial coalesced state of a dried but unbaked film of a latex of a polymer which is relatively hard. By unoriented it is meant that the tape or ribbon has not been subjected to the unilateral longitudinal stress which tends to align the individual molecules in the direction of the major axis of the tape or ribbon.

The advantages and benefits of the present invention, as well as the operation of the process, will be more apparent from the following description and the appended drawings which are illustrative of a preferred embodiment of the process and of an apparatus useful for carrying out the process.

In the drawings:

FIGURE 1 illustrates in schematic outline a procedural sequence to be followed in carrying out the process and an apparatus useful therein,

FIGURE 2 represents a cross section of a typical rolled filament,

FIGURE 3 illustrates a cross section of a rolled filament of generally oval or elliptical peripheral outline,

FIGURE 4 represents a cross section of a rolled filament having a solid monofilamentary core, and

FIGURE 5 represents the point in the procedural sequence wherein a core material may be inserted into the rolled filament.

In the embodiment illustrated in FIGURE 1 a fused but unoriented tape or ribbon 10 is fed from a suitable inventory (not shown) through a guide means 11 which may take the form of a comb, grooved roll, or other conventional device. The tape 10 then passes about snubbing rolls 12 into a groove located in first grooved roll 13. Following the grooved roll 13, the tape it} next passes over a second grooved roll 14 so located as to deflect the path of travel of the tape 10 as it leaves roll 13. Following grooved roll 14, the tape or ribbon passes over a second pair of snubbing rolls 15 operated at a peripheral speed greater than that of snubbing rolls 12 so as to impart a continuous orienting stress on the tape 10 as it passes through the shaping steps. Following snubbing rolls 15, the tape 10 is passed to suitable collecting means 16, such as a conventional winding frame. It will be appreciated that, although only one tape is illustrated in FIGURE 1, the process is adaptable to the simultaneous treatment of a plurality of tapes arranged parallel to each other.

The string-up for a plurality of ends is easily accomplished if the second grooved roll 14 is mounted on its shaft so as to be laterally adjustable. In this case the grooves in rolls 13, 14 may be aligned during string-up and the second roll 14 subsequently adjusted to the desired lateral deflection. In addition, by having second roll 14 laterally adjustable, minor changes in deflection may be accomplished without stopping the process.

As shown, the present process requires the use of at least two grooved rolls or their equivalent. It has been found that the function of the groove in each roll is different from its counterpart in the other roll and that, as a result, the shape of the groove in one roll that provides optimum results is different from that in the other roll. In the first grooved roll 13 the grooved design is preferably of a shallow U shape. The function of this groove is to prevent the tape or ribbon from veering from its normal path of travel until rolling commences and it also gives one edge of the tape a start toward rolling when it is deflected from its original path of travel.

The preferred groove design for grooved roll 14 is deeper than that of the first grooved roll and is of a V shape having a rounded bottom. The function of this groove in roll 14 is to impart a torque action on the tape as it is passed through the groove under the orienting stress. The rounded bottom prevents distortion of the shape of the newly formed filament.

With most organic, thermoplastic materials it is preferred to heat each of the rolls. For the normally crystalline vinylidene chloride polymers it has been found to be preferable to employ temperatures on the first roll of from about 60 to 75 C. The heated first roll tends to soften the tape somewhat and facilitates the subsequent rolling. With this preferred class of polymeric materials it is preferred to heat the second roll to from about 75 to C. to set the rolled configurations. Useful temperatures with other polymeric materials will be known or may be easily determined by simple preliminary experiment.

As shown and mentioned in the illustrated embodiment, the roll is imparted to the tape by the use of offset grooves in rolls. The amount of offset may be varied within certain limits. In general, it may be stated that the greater the amount of offset or of deflection of the tape the more tightly rolled will be the resulting filament. As a general guide, it will be found that an offset of from about to inch may be employed to produce the rolled filaments of this invention.

It has been also found that the width of the tape used should be no greater than the groove opening. If the tape width is greater, the rolling action is poor, erratic, and unreproducible. However, tape widths equal to or less than the width of the groove opening exhibit the controlled rolling action that results in useful filamentary articles. If it is desired to increase the denier, it is possible to superpose two or more tapes or ribbons upon one another and pass them simultaneously through the same groove sequence. In regard to denier it should be apparent that the process is readily adaptable to the production of a wide range of deniers of from about 100 denier or less, up to 2,000 denier or greater. The denier may be varied by the choice of organic, thermoplastic, resinous material, the width and thickness of the ribbon, and the core material. Also, denier may be lowered by hot stretching the filaments to a fraction of their original dimensions.

It is imperative in the preparation of the filaments that an orienting longitudinal stress be applied to the tapes or ribbons during the shaping process. This aids in the rolling and in the setting of the rolled cross section.

It has been found that the tightness of the rolling exerts an influence on the cross-sectional outline of the filament. Loosely rolled filaments tend to be flattened by the subsequent snubbing action into a cross section similar to that of FIGURE 3. Tightly rolled filaments retain the cylindrical outline, such as that of FIGURE 2.

In a special embodiment of the process a core material is inserted into the center of the rolled monofilament, as illustrated in FIGURES 4 and 5. This core material may be a monofilament, a yarn, or any other continuous filamentary structure. The chemical composition of the core material may be the same or different than that of the rolled filament. The core material may be orientable or non-orientable. Thus, solid cylindrical monofilaments of thermoplastic, resinous materials, such as vinylidene chloride polymers, polystyrene, polyvinyl chloride, polyvinyl acetate, and other well-known thermoplastic materials, may be used as the core. Likewise, fibers and filaments of polyacrylonitrile, nylon, polyethylene, and glass may be employed. The choice of core material will depend to large extent upon individual preference and on the contemplated end use of the composite filament.

The core material is conveniently and advantageously inserted into the rolled filament at the point of first deflection of the tape or ribbon from the first grooved roll. This is illustrated in FIGURE 5 where the tape is passing through a groove in roll 13 and, as it leaves roll 13, a core material 17 is laid against the tape as it is starting to curl. It has been found to be highly desirable to have at least two layers of the tape or ribbon surrounding the core material.

The process of the present invention permits the preparation of the rolled filamentary articles with or without a core material. This process results in several benefits. First, it is capable of continuous operation and is adaptable for fitting into an integrated filament-making scheme that would include the tape or ribbon-making procedural sequence immediately preceding the present process. The rolled filaments resulting from this process are characterized generally by a higher tenacity and a better hand than the tapes or ribbons from which they' are formed. In addition, the rolled filaments are characterized by uniform cross-sectional dimensions and denier and by the absence of any fray'ed, uneven, or torn edges as would be present in the flat tapes or ribbons. The process is capable of producing rolled filaments of generally round or oval or elliptical section. The process adapts itself to the production of rolled filaments of a wide variation in denier. Likewise, rolled filaments of any useful filamentary dimensions may be prepared. The process is adaptable without major retooling to a wide diversity of thermoplastic materials. Many other benefits or advantages will be apparent to the skilled worker.

The tapes or ribbons utilizable in the process may contain the common and conventional additives employed in polymer formulation. These include typically colorants, such as dyes and pigments; light and heat stabilizers; antioxidants; fillers; and others. These may be in 6 corporated prior to the fabrication of the tape or ribbon, or, when possible, included by impregnation or other known means into the resultant rolled filament.

The operation of the process will be apparent from the illustrative examples wherein all parts and percentages are by weight.

Example 1 A copolymer of 97 percent vinylidene chloride and 3 percent acrylonitrile was fabricated into a continuous coherent fused film by the continuous localized coagulation of a latex of said polymer followed by washing, slitting, drying, and fusing. Each tape was 0.0017 inch thick and slit to inch width. The fused but unoriented tapes were passed over snubbing rolls maintained at 30 C. and operated with a peripheral speed of 24 feet per minute. The tapes were then passed over intermediate snubbers at 31 feet per minute. The tapes then passed over a pair of grooved, free-turning rolls, the first roll located 3 inches from the intermediate snubbing rolls while the second grooved roll was located 3 inches from the first with the grooves offset /2 inch sideways from the grooves in the first. Each of the rolls was heated to C. The width of the groove on the first roll was A inch at the surface and was U-shaped to a depth of 1 inch. The groove in the second roll was inch wide at the surface, inch deep and was V- shaped with a rounded bottom. The tapes, after leaving the grooved rolls, passed over a third pair of snubbing rolls operated at feet per minute and then to spools at 107 feet per minute. The resulting filament was a rolled structure having a hollow central portion with the void space amounting to approximately 60 percent of the cross-sectional area of the filament. The tenacity of the filament was about 2.7 grams per denier, the elongation 16 percent, and the size of denier.

In a similar manner ribbons of a copolymer of about 96 percent vinylidene chloride and about 4 percent ethyl acrylate; of a linear polyethylene; and of polypropylene were passed through the identical sequence and a useful rolled filament resulted.

By the same procedure, rolled filaments of 1,100 denier were prepared from the indicated polymeric materials by increasing the width of the ribbon and also by superposing 2 and 3 ribbons upon one another and passing them through the indicated sequence.

Example 2 Tapes and ribbons, as prepared in Example 1, were passed over the grooved rolls heated at 75 C. As the tape left the first grooved roll, a 40 denier nylon monofilament was inserted into the rolled filament. The resulting filament was tightly rolled against the nylon monofilamentary core.

In a similar manner, fiberglass multi-filament yarn, and polyethylene monofilaments were inserted into the rolled tapes at the same point in the procedural sequence.

What is claimed is:

1. A process for the preparation of rolled filamentary articles comprising the passage of a continuous, coherent, unoriented, flexible ribbon of an organic, thermoplastic, resinous material in flat, undistorted form into first guide means, removal of said ribbon from said first guide means so that a plane through the longitudinal axis of said ribbon and perpendicular to the width of said ribbon is at an acute angle to an extension of said plane of said ribbon entering said first guide means, the passage of said ribbon through a second guide means disposed parallel to said first guide means so as to divert or to deflect said ribbon into a direction of travel substantially parallel to and finitely displaced from said plane of said ribbon entering said first guide means while imparting a torque to said ribbon between said first and second guide means to cause said ribbon to roll into a filament of an involute cross section having the original edges of said ribbon essentially parallel to the longitudinal axis of the filament and while maintaining suificient tension on said filament throughout the process to impart thereto orientation parallel to the longitudinal axis of said filament.

2. The process claimed in claim 1 wherein said organic, thermoplastic, resinous material is a normally crystalline vinylidene chloride polymer.

3. The process claimed in claim 2 wherein said normally crystalline vinylidene chloride polymer is a copolymer of from 92 to 99 percent vinylidene chloride and from 8 to 1 percent acrylonitrile.

4-. The process claimed in claim 2 wherein said normally crystalline vinylidene chloride polymer is a copolymer of from 92 to 99 percent vinylidene chloride and from 8 to 1 percent of an alkyl acrylate.

5. The process claimed in claim 1 wherein said organic, thermoplastic, resinous material is a polyolefin.

6. The process claimed in claim 5 wherein said polyolefin is a polyethylene.

7. The process claimed in claim 5 wherein said polyolefin is polypropylene.

8. The process claimed in claim 1 wherein a filamentary core material is inserted into the rolled filament at a point in the procedural sequence where said ribbon leaves the first guiding means.

9. The process claimed in claim 8 wherein said filamentary core material is a polyethylene monofilament.

10. The process claimed in claim 8 wherein said filamentary core material is a nylon yarn.

11. The process claimed in claim 8 wherein said filamentary core material is a yarn of glass fibers.

12. The process claimed in claim 1 wherein said unoriented, flexible ribbon is not more than one inch in width and is from 0.001 to 0.005 inch in thickness.

13. The process claimed in claim 1 wherein said ribbon is warmed to a temperature below the softening temperature of said organic, thermoplastic, resinous material.

References Cited in the file of this patent UNITED STATES PATENTS 1,585,622 Heany May 18, 1926 2,176,019 Cohoe Oct. 10, 1939 2,321,726 Alderfer June 15, 1943 2,336,100 Jacque Dec. 7, 1943 2,363,457 Alderfer Nov. 21, 1944 2,407,926 Hamilton Sept. 17, 1946 2,589,514 Stalter Mar. 18, 1952 2,612,679 Ladisch Oct. 7, 1952 2,674,025 Ladisch Apr. 6, 1954 2,825,624 Fry Mar. 4, 1958 2,829,421 Hanson Apr. 8, 1958 2,858,186 Frost Oct. 28, 1958 2,918,784 Faircloth Dec. 29, 1959

Claims

1. A PROCESS FOR THE PREPARATION OF ROLLED FILAMENTARY ARTICLES COMPRISING THE PASSAGE OF CONTINUOUN, COHERENT, UNORIENTED, FLEXIBLE RIBBON OF AN ORGANIC, THERMOPLASTIC, RESINOUS MATERIAL IN FLAT, UNDISTORTED FORM INTO FIRST GUIDE MEANS, REMOVAL OF SAID RIBBON FROM SAID FIRST GUIDE MEANS SO THAT A PLANE THROUGH THE LONGITUDINAL AXIS OF SAID RIBBON AND PERPENDICULAR TO THE WIDTH OF SAID RIBBON IS AT AN ACUTE ANGLE TO AN EXTENSION OF SAID PLANE OF SAID RIBBON ENTERING SAID FIRST GUIDE MEANS, THE PASSAGE OF SAID RIBBON THROUGH A SECOND GUIDE MEANS, DISPOSED PARALLEL TO SAID FIRST GUIDE MEANS SO AS TO DIVERT OR TO DEFLECT SAID RIBBON INTO A DIRECTION OF TRAVEL SUBSTANTIALLY PARALLEL TO AND FINITELY DISPLACED FROM SAID PLANE OF SAID RIBBON ENTERING SAID FIRST GUIDE MEANS WHILE IMPARTING A TORQUE TO SAID RIBBON BETWEEN SAID FIRST AND SECOND GUIDE MEANS TO CAUSE SAID RIBBON TO ROLL INTO A FILAMENT OF AN INVOLUTE CROSS SECTION HAVING THE ORIGINAL EDGES OF SAID RIBBON ESSENTIALLY PARALLEL TO THE LONGITUDINAL AXIS OF THE FILAMENT AND WHILE MAINTAINING SUFFICIENT TENSION ON SAID FILAMENT THROUGHOUT THE PROCESS TO IMPART THERETO ORIENTATION PARALLEL TO THE LONGITUDINAL AXIS OF SAID FILAMENT.