IL31455A - Method of producing soil resistant acrylic fibers - Google Patents

Description

METHOD OF PRODUCING 30 IL RE8I 8TANT ACRYLIC FIBERS » ' > . . . ,' ■·.

Acrylic fibers are rendered soil resistant in a continuous vet spinning process wherein the coagulated fibers are washed and stretched, passed through a first finish bath containing standard textile processing finishes, partially dried, impregnated with a second finish composition having anti-soil properties, and essentially completely dried to produce a textile fiber having durable soil resistant properties.

This invention relates to the manufacture of synthetic textile fibers, and specifically deals with the continuous manu- facture of acrylic fibers which are" resistant to soiling by virtue of a soil resistant finish applied thereto.

In the textile field, and particularly in the carpet industry where the popularity of light color shades and the use of carpets in entrance ways have increased in recent years, the need for soil resistant fibers has become more evident. The textile industry has responded to this need with extensive research into the area of special textile f nishes which impart the desired soil resistant properties to the synthetic fibers.

One of the most effective finishes developed incorporates a zirconium salt in an acidic aqueous solution, preferably containing as an additional ingredient a nitrogen containing base.

It was discovered that the treatment of textile articles such as woven cloth or tufted carpets with these specific finish compositions imparted a high degree of soil resistance to the article.

For reasons of convenience and economics, it is desirable to apply the zirconium containing finish composition to the treating the finished textile goods. In the production of« acrylic fibers by conventional wet spinning techniques, a standard fiber finish comprised of various lubricating, softening and/or antistatic agents is applied to the spun fiber from an aqueous bath after the fiber has been washed free of residual solvent. After the application of finish, the fiber is dried by passing it around and over heated drying rolls. However, when the soil resistant finish composition is incorporated into the standard finish bath, production is disrupted by broken filaments and solids deposits on the drying rolls. These difficulties make the commercial production of a soil resistant fiber by this technique impossible.

This invention overcomes the difficulties pointed out ' above by applying a soil resistant finish to acrylic fibers produced by conventional wet spinning techniques through first applying to the washed fibers a conventional textile finish, partially drying the fibers, then applying the soil resistant finish, and finally drying the fibers to essentially complete dryness.

The conventional finish may be applied to the fiber by passing the fiber through an aqueous bath. The fiber, then contain ing about 70% moisture at ambient temperature, is heated sufficiently to increase the temperature to above about 70°C. and to reduce the moisture content to between about 55 and 5%, and , the soil resistant finish is then applied to the hot fiber. The fiber is finally dried to less than about 0.5% moisture content and processed in accordance with conventional techniques to produce tow or staple for convers ion into textile articles. dried by passing over, and. around hot drying rolls with no ¾p-pre_ciable solids deposition or filament breakage, occurring. The resulting fibers possess significantly greater resistance to soilage than fibers treated with the conventional textile finish alone. The method of this invention provides for the continuous production of soil resistant fibers in a commercial manner with onl minor changes required of the conventional spinning equipment.

It is therefore an object of this invention to provide a method for the continuous production of soil resistant synthetic fibers.

Another object of this invention is to provide a method for the continuous production of acrylic fibers which possess a durable soil resistant finish without associated broken filaments and solids deposits.

These and other objects and advantages will become more readily apparent when read in conjunction with the remainder of the specification and considered along with the included examples.

According to a preferred embodiment of the present invention, an acrylic fiber is wet spun according to conventional techniques wherein a spinning solution comprised of polymer and solvent is extruded through a spinning orifice into a coagulation bath comprised of water and solvent. The coagulated filaments are stretched to achieve molecular orientation, and washed free of residual solvent.

The wet spinning technique is a well known process for the production of synthetic fibers. The acrylic fibers which ma be produced in this manner include, in addition to polyacryloni-trile, a wide range of copolymers and terpolymers which contain a preponderance of acrylonitrile. Such polymeric compositions are described in detail in israelii. Patent No. 21.922.

After washing, the spun to is passed through a bath where conventional textile finishing compounds are applied to the fibers. These compounds are necessary to assure that the fiber will process well on textile machinery when being converted into yarns and fabrics. One example of such a conventional textile finishing bath is an aqueous solution containing 2 percent of a textile lubricating agent comprised of 60 percent sorbitan monopalmitate and 40 percent castor fatty acid with 200 moles ethylene oxide, and 1 percent of an antistatic agent such as soya dimethylaminoethyl etho.suIfate. The finish may in addition contain textile softening agents if desired, and other lubricating and antistatic agents may be substituted for those specifically mentioned above. Such agents are well known and widely used throughout the textile industry.

As the tow leaves the finish bath, it is passed between two wiper bars to remove excess finish solution and thence onto the drying rolls. At this point, the fibers in the tow normally contain between 60 and 70 percent moisture and are at ambient temperature of about 25 to 30°C.

On the drying rolls, the tow is laced between an upper horizontal row of rolls and a lower horizontal row of rolls, pass ing alternately over an upper roll and under a lower roll in a serpentine path. Each roll is electrically or steam heated to a although higher or lower temperatures may be used. As the tow" passes around each heated roll, part of the moisture in the tow is driven off, the exact amount being a function of roll temperature and tow contact time and area.

In a preferred embodiment of the present invention, the tow is passed around 2 to 8 pairs of heated rolls, and preferably around 4 to 6 pairs of rolls heated to between 1550C. and 165°C. and operating at a speed such that the moisture in the tow is reduced to between 55 and 5 percent while the surface temperature of the tow is heated to at least about 70°C. and preferably to above 80eC. The heated fibers are then impregnated with the soil resistant finish of the composition as hereinbefore described. This finish is conveniently applied to the tow as a spray, although a pad bath may be used with good results.

It is critical to the successful practice of this invention that the process steps as described above be carried out in the order described. Specifically, it is necessary that the conventional textile finish be applied first to the fiber, that the fiber then be partially dried, and that the soil resis-tant finish be applied to the hot fiber. After the application of the soil resistant finish , the tow is laced over an additional series of heated rolls to finally dry the fiber and reduce the fiber moisture content to less than about 0.5 percent. The ¾inal drying operation also causes any voids within the fiber commonly associated with wet spinning to collapse and thereby increase fiber density.

The dried fiber is then processed oh into yarns and dried fiber may be crimped, steam relaxed, cut to staple, and converted into yarn using standard cotton or wool processing machinery. If the fiber is of a high denier,, such as about 15 denier, it can be processed on 'woolen machinery to form yarns suitable for tufting or weaving into high quality carpets. Carpets made from such yarns -spun in accordance with this invention possess markedly superior resistance to soiling, and are also easier to clean when soiled.

The effectiveness of the method of this invention in imparting soil resistant properties to synthetic fibers is illustrated by preparing tufted carpet samples from the treated fibers and subjecting these samples to a standard laboratory soiling procedure. Specifically, samples of carpet 2" by 4" (5.08 era by 10.16 cm) are measured for initial reflectance, soiled with an artificial soil and cleaned by vacuuming, and finally measured for soiled reflectance.

The difference in the reflectance readings indicate the anti-soiling properties or characteristics of the samples, i.e., a large number indicates poor anti-soiling properties whereas a small number indicates good anti-soiling properties. The photo reflectance readings are measured by using a Photo-volt Reflectance Meter (Model No. 610, Photovolt Corp. , New York City, New York) . The samples of the textile articles are soiled by either of two methods, i.e. by an artificial soiling test or by a floor soiling test. The artificial soiling test is accomplished by placing the samples in a one gallon (3.78 liters) wide mouth jar having therein two glass rods opposite sides of the jar and containing 10% (based on weight of the sample) of artificial soil and 10 number two rubber stoppers. The artificial soil has the following composition (the soil is sifted through a 30 mesh screen) : Peat 22,3% Silica gel 2.1% Cement 2.1% Kaolin clay (peerless) 2.1% Molacco furnace black 0.2 Red iron oxide 0.1 Sawdust 52.5 Calcium carbonate 10.9% Animal charcoal 6.6% Mineral Oil 1.1% TOTAL 100.0% The jar is then sealed, placed on a ball mill and rotated at ' 95-100 rpra for 30 minutes in a clockwise direction and 30 minutes in a counter-clockwise direction at the same rpm. Thereafter the samples are removed from the jar, vacuumed , and the photo reflectance readings of the two samples measured. The difference between the average initial reflectance readings and the average of the final reflectance readings indicate the degree of soil . resistance. As mentioned earlier, a small photό reflectance difference number indicates a good ant i-soiling property whereas a large. number indicates a poor anti-soiling property of the textile article.

Control samples, that is samples which have been - To confirm the results of the laborator soiling test, a floor soil test was also conducted for selected samples.

The procedures of evaluation was the same as for the artifically soild samples except that the samples are soiled by placing them in the pathway of a well travelled walk way in order that they might be soiled by natural means. The validity of the laboratory soiling technique was confirmed by the actual floor tests.

In order that the present invention may be more' fully understood, the following examples are given primarily by, way of illustration. No details appearing therein should be construed as limitations on the present invention, except as they appear in the appended claims. All percentages are by weight unless otherwise noted.

EXAMPLE I Acrylic fibers of 15 denier were wet spun by extruding a spinning solution comprised of 26 parts of a polymer consisting of 93 percent acryloni trile and 7 percent vinyl acetate, 74 parts of dimethylacetamide solvent, and 0.45% based on polymer weight of i<>2 delusterant through a spinnerette; into an aqueous- coagulation bath containing 55 percent solvent at 40eC. The filaments were passed from the coagulation bath into a boiling water cascade where they were stretched 6 times and simultaneously washed essentially free of solvent. The filaments-were then passed through a bath containing an aqueous solution of a conventional finish comprised of 66 percent of a lubricating agent agent consisting of soya dimethylaminoethyl etho sulfate. After leaving the finish bath and being stripped of excess finish,' the filaments were passed around 4 pairs of drying rolls heated to about, 150°C. with 70 lb. (4.9 Kg/cm ) steam. The moisture content of the fibers was reduced from about 70 percent when leaving the finish bath to about 20 percent when leaving the fourth roll,, and surface temperature of the fiber was increased to 83°c.

As the tow proceeded from the fourth roll, it was sprayed with an excess of a second finish containing in aqueous solution a combination of -the conventional finish composition described above and a soil resistant finish comprised of zir¬ conium acetate and sulfamic acid. The tow then proceeded over the remainder of the drying rolls where its moisture content was reduced to about 0.2 percent.

The amount of finish applied to the fiber from the conventional bath and from the spray was varied to determine the effectiveness of the treatment at various levels. The levels 0. evluated are shown for each condition in Table I.

A. ■ ' " After being crimped and steam relaxed, the tow was cut to 4 inch (10.16 cm) staple and processed into carpet yarn on woolen textile machinery. The yarn was finally tufted into carpet samples which were submitted to the laboratory soiling test previously described in order to determine the effectiveness of the finish treatment. The results of this evaluation are given in Table I below.

EXAMPLE III ' The process of Example I was repeated except that the spinning solution was comprised of 25 parts of an acrylic polymer containing 89.'8% acrylonitrile, 7.5% vinyl acetate, and 2.7% vinyl bromide, and 75 parts of dimethylacetamide solvent., The soil resistant finish was applied to the fiber at two different concentrations as shown in Table III. Carpet reflectance. readings were taken before and after laboratory soiling to measure propensity of the various yarn samples according to the method of Example I, and the results of the test are shown in Table III below.

TABLE III (a) pH adjusted with sodium metasilicate EXAMPLE IV The process of Example I was repeated except that the spinning solution was comprised of 16.2 parts of a polymer consisting of 88.7 percent acrylonitrile, .5.3 percent vinylacetate, and 6.0 percent methyl vinyl pyridine, 2.4 parts of polyvinyl- chloride, and 81.4 parts dimethylacetamide solvent. The conventional finish (C.F.) was an aqueous solution of the lubricating agent only, the antistatic agent being omitted for this evaluated for a wide range of finish application levels with the results appearing in Table IV.

TABLE IV ·' The above data show the excellent results obtained by applying as little 0.05% zirconium acetate to. the fiber by the method of this invention.

Although the description of the instant invention has been directed primarily toward the treatment of acrylic fibers which are generally defined as those fibers wherein .acrylonitrile constitutes at least 85 percent of the fiber forming constituents, the invention is not limited thereto, but is also applicable to the treatment of wet spun modacrylic fibers. The modacrylic fibers generally contain at least 60 percent acrylonitrile and up to 40 percent of one or more other copolymerizable monomers designed to im art special ro erties to the fiber. For exam le it is know to copolymerize acrylonitrile with vinylidene chloride, vinyl bromide, or other halogen containing monomers in order to produce a fiber having a high degree of flame resistance.

It is also contemplated that other compounds may be ... substituted for the ingredients of the soil resistant finish as described, and such substitution is considered to be within the scope of the invention describing a novel method for treating tows.

The foregoing illustrates the essential features'* of' the invention as well as some of the manners .in which it may be practiced. Various changes and modifications may be made in practicing the invention without departing from the spirit and scope thereof, and therefore the invention should not be limited except as defined in the appended claims.

Claims (1)

WHAT IS CLAIMED IS A method of continuously treating acrylic fibers rendering soil characterized by applying to acrylic fibers a first finish composition of an aqueous mixture containing compounds selected from the group consisting of textile lubricants softeners and mixtures heating and partially drying the fibers after application of the aqueous applying to said partially dried fibers a second finish comprising an aqueous solution of at least one soil resistant and thereafter drying the fibers to a moisture content of less than The method of Claim characterized in that the fibers are partially dried by applying sufficient heat to the fibers to Increase the surface temperature of the fibers to greater than about The method of

1. Claim 1 characterized by method of characterized and stretchin an containing polymer solution to orm textile applying to the textile finish composition heatin fibers to a surface temperature of at least about while simultaneousl reducin fiber content to between 5 arid 55 applying to heated fibers seoond finish composition containing zirconium acetate and sulfamic and finally dryin fibers to a moisture content of less than about 5 The method of Claim characterized that the second is sprayed as an aqueous solution onto heated A textile article comprised of synthetic fibers obtained by a method of any of Claims 1 to insufficientOCRQuality