US2980982A - Fibrous article - Google Patents

Description

Apnl 25, 1961 J. E. COSTA ETAL 2,980,982

FIBROUS ARTICLE Original Filed May 27, l954 John E. Cos fa Edgar W Le Boeuf' L/oydE. Lef'evre ATTORNEYS.

rats 1 re FIBROUS ARTICLE Original application May 27, 1954, Ser. No. 432,826,

now Patent No. 2,853,741, dated Sept. 30, 1958. Divided and this application Feb. 6, 1958, Ser. No. 713,672

5 Claims. (Cl. 28-78) This invention relates to a new fibrous product and to a process for producing the same. More particularly, it relates to such products made from polymeric materials.

This application is a divisional application of U5. Serial No. 432,826, filed May 27, 1954 now issued as US. Patent No. 2,853,731, dated September 30, 1958.

The production of continuous roving has long been a necessary step in the production of yarn for the textile industry. One of the oldest and most common methods employed to produce such roving has been to card a mass of staple fibers so that the individual fibers are brought into approximately parallel relationship, followed by twisting and drawing the resulting sliver. There are many time-consuming steps in such a method. The roving is held together by the intermeshing of the individual fibers, by the crimp in the fibers, and by surface characteristics of the individual fibers. The strength of the yarn is dependent to a large extent on the resistance these short fibers have to sliding past each other. Yarns made from staple fibers have a characteristic resiliency and hand which is highly desirable for articles of wearing apparel. Still another method produces a yarn by extruding or spinning a plurality of continuous fibers, crimping, twisting, and drawing the tow into a yarn. That method is mostly associated with synthetic fibers that have smooth surfaces and even when crimped tend to slide easily past one another. Up to now that method has been useless for producing yarns for wearing apparel because it has been impossible to achieve a desirable hand, such as that found in yarns made from staple fibers, in yarns spun from continuous fibers. In order to obtain the proper hand it has been necessary to stapilize the continuous filaments and then carry out all of the usual steps of converting the staple fibers into a continuous roving. Such a method is impractical and costly in operation. It would be desirable to have a method of producing a tow of continuous fibers which could be twisted directly into a yarn having a desirable hand.

It is the principal object of this invention to provide a continuous fibrous or filamentary article from synthetic polymers which may be twisted directly into a yarn having the hand of a yarn made from staple fibers.

The above filamentary article and other related ob jects are prepared by a process whereby a unilaterally oriented film of a normally crystalline polymeric material is shredded into a continuous fibrous web, such shredding being only partially complete, so that the individual fibers are cohered to each other at random intervals. The fibrous web made by this process may be twisted into a yarn without further processing, eliminating several of the operational steps usually required when yarn is prepared from staple fibers. The fibers, being linked to other fibers, show exceptional resistance, to slippage against one another. Yarns produced in accordance with this invention have the same hand as yarns prepared from staple fibers.

The films are conveniently prepared from an aqueous latex of the synthetic polymer. Any polymers whose latexes will form a continuous, self-supporting, orientable film may be employed in making the fibrous articles of this invention. may be mentioned the copolymers of vinylidene chloride with other copolymerizable monomers such as acrylonitrile, vinylchloride, and vinylacetate, in which the vinylidene chloride is present in the major proportion. Useful films may also be cast from a solution of a polymer although many disadvantages, such as the high cost and flammability of many solvents, and the difficulty in preparing concentrated polymer solutions, usually make this procedure less attractive than that using a latex. Other useful films may be formed by melt extrusion of polymeric bodies.

The preparation of latexes capable of forming films is old in the art. Typically the polymerizable materials are mixed into an aqueous phase containing a polymerization catalyst and an emulsifier for the polymerizable materials. Polymerization is initiated by warming the mixture and allowing it to proceed with agitation until substantially complete.

Before casting the latex into a film it may be necessary to blend therein a thickener. As is well known in the art, some latexes will form films without a thickener, whereas others require one and simple preliminary experiments will determine if one is necessary.

The films are easily prepared from latexes or solutions by casting the latex or solution onto a flat surface and drying the resulting deposit. Other techniques will be apparent to those skilled in the art. The films so prepared are usually of a thickness of from about 0.001 to 0.01 inch although films of greater or less thickness may be obtained by adjustment of the solids content. However, films of the stated thickness range are preferred, since they result in fibrous articles of optimum strength, flexibility, and other properties.

With those films that are made from crystalline polymers, it is necessary to heat the films to a temperature at which the crystallites will melt followed by supercooling the film, and then to stretch the film in one direction to obtain the desired unilateral orientation. After orientation the films may be shredded at any time. Films of non-crystalline polymers may be oriented by stretching them in a heated condition, and the orientation may become set in the film by sudden chilling.

The preparation of the fibrous article and its appearance and structure will be more apparent from the annexed drawings and the following description. In the drawings;

Fig. 1 shows in diagrammatic elevation a preferred embodiment of an apparatus for preparing the articles; and

Fig. 2 is a magnified view of a portion of the fibrous article.

An especially useful device for shredding the films is shown in diagrammatic cross section in Fig. 1 of the accompanying drawing. In that device the unilaterally oriented film is fed through the nip between a driven revolving brush 10 and a stationary brush 11 positioned so that its bristles barely engage those of the rotary brush 10. The revolving brush 10 rotates in the direction of travel of the film 12. The pressure between the two brushes that is necessary to produce the partial shredding will depend on several factors, such as the thickness of the film, the degree of orientation, and the stiffness of the brushes. Simple preliminary experiments will readily disclose the proper adjustment of the brushes to provide the necessary shredding action. The rate of travel of the film 12 may be controlled by running the film 12 through a pair of driven pinch rolls 13 before As typical examples of such polymers:

being brushed. A windup roll or other similar collecting device (not shown) may follow the brushes (10, 11) and tension rolls 14, to collect the partially shredded film. It should be understood that the invention is not limited to any particular apparatus, and that the above description represents only a preferred embodiment of a device for carrying out the method of the invention. However, methods such as turning and slicing, which produce continuous unconnected fibers are not suitable for use in the invention.

The product which is formed in accordance with the method of this invention is a fibrous article consisting of a longitudinally fibrillated coherent sheet of fibroid segments physically connected to each other at random intervals by short links which are an integral part of each of those fibroid segments. The form of the article is more apparent from the highly magnified sketch of a portion of a fibrous article as shown in Fig. 2. From this sketch it can be seen that the fibroid segments 15 are connected at random intervals at linkage points 16. It can also be seen that the links 16 are a part of both of the fibroid segments 15 which they connect and are not welded, glued, tied, or in any other manner tacked onto or adhered to the fibroid segments 15. The latter methods would be time-consuming, expensive, and impractical, and the product produced by such methods would not enjoy the advantages inherent in the product of this invention consisting of a single integral network.

By way of illustration, a film-forming aqueous latex of a polymer consisting of 97 percent vinylidene chloride and 3 percent acrylonitrile was cast into a continuous film, which, when dried, was about 0.5 mil thick. The dried film was heated to about 180 C. and unilaterally stretched to seven times its original length. The oriented film was then passed through the nip of a revolving brush and a stationary brush and the pressure between the brushes adjusted so that a fibrous article substantially as described in this specification was formed. The continuous tow thus produced was twisted into a yarn, and articles made therefrom had a hand typical of similar articles made from staple fiber yarns, but the individual yarns of the invention were much stronger than staple fiber yarns of the same composition and denier.

What is claimed is:

1. A continuous, coherent, fibrous article produced from an oriented film composed essentially of a normally crystalline polymer, said article being a longitudinally fibrillated fibrous web, the fibroid segments forming said web being in random coherent association.

2. The continuous coherent fibrous article claimed in claim 1 wherein said normally crystalline polymer is a copolymer of vinylidene chloride and at least one other copolymerizable monomer.

3. The continuous coherent fibrous article claimed in claim 2 wherein said other copolymerizable monomer is acrylonitrile.

4. The continuous coherent fibrous article claimed in claim 2 wherein said normally crystalline polymer is a copolymer of 97 percent by weight of vinylidene chloride and 3 percent by weight of acrylonitrile.

5. The continuous coherent fibrous article claimed in claim 1 having a thickness when in planar form of from about 0.001 to 0.01 inch.

References Cited in the file of this patent UNITED STATES PATENTS 2,106,896 McCulloch et al Feb. 1, 1938 2,185,789 Iacqu Jan. 2, 1940 2,603,620 Walter et al. July 15, 1952

Claims (1)

1. A CONTINUOUS, COHERENT, FIBROUS ARTICLE PRODUCED FROM AN ORIENTED FILM COMPOSED ESSENTIALLY OF A NORMALLY CRYSTALLINE POLYMER, SAID ARTICLE BEING A LONGITUDINALLY FIBRILLATED FIBROUS WEB, THE FIBROID SEGMENTS FORMING SAID WEB BEING IN RANDOM COHERENT ASSOCIATION.

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