WO2017176604A1

WO2017176604A1 - Light color /low resistance anti-static fiber and textiles incorporating the fiber

Info

Publication number: WO2017176604A1
Application number: PCT/US2017/025642
Authority: WO
Inventors: Gregg T. LOWERY; Harrie P. Schoots; Cihan UZUNPINAR
Original assignee: Ascend Performance Materials Operations Llc
Priority date: 2016-04-06
Filing date: 2017-04-01
Publication date: 2017-10-12
Also published as: TWI744305B; TW201807274A

Abstract

The present invention relates to a bi-component antistatic fiber produced by means of a conjugant / melt extrusion spinning process where the fiber comprises TiO₂and nylon with carbon black as the conductive component of the fiber. At TiO₂ loadings in the range of 20-30% by weight, the TiO2 camouflaged the normally black surface carbon stripes, and the resultant light colored yarn was comparable in conductivity to darker yams. The resulting yam is suitable for use in light colored apparel, especially where certain surface resistance levels are required in light colored fabrics.

Description

Light Color / Low Resistance Anti-Static Fiber and Textiles

Incorporating the Fiber

CLAIM FOR PRIORITY

This application is based on United States Provisional Application Serial No. 62/319, 122, filed April 6, 2016, entitled "Light Color / Low Resistance Antistatic Fiber, the priority of which is hereby claimed and the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a bi-component anti-static fiber produced by means of a conjugant / melt extrusion spinning process where the conductive component is composed of carbon black stripes on the surface of the fiber. The fiber is suitable for various applications, especially where certain surface resistance levels are required in light colored textiles.

BACKGROUND OF THE INVENTION

In fabric applications where synthetic fibers are used, friction can generate static electricity. Static electricity effects can cause static cling in fabrics, dust attraction to fabrics and can result in nuisance electrical shocks as a person walks across an unprotected carpet. More serious consequences can also result and harm equipment and/or an individual from electrostatic discharges. For example, electrostatic discharges can damage computers and other electronic equipment. In some cases, such as in flammable

atmospheres, electrostatic discharges can result in a fire or explosion. Static buildup and discharge can also affect the efficiency and productivity of fiber conversion methods such as knitting and weaving. The use of anti-static fibers in fabrics has demonstrated success in solving several issues caused by static electricity. Typically carbon black is employed as the anti-static agent compounded within a polymer such as nylon to dissipate the electrical charges. As more fabric producers realize the potential benefit of anti-static fiber, or fibers having electrically dissipative properties, the materials desired often include carbon black. Alternates to carbon black have been metal oxides (such as tin oxide) or the use of metal wires woven or knitted into fabrics. The use of carbon black results in issues with color and the ability to dye the resulting fabric a light color.

In many cases, TiC is compounded with the non-conductive component to hide or camouflage the carbon component. There are a variety of T1O2 types used in fiber production. The type used can impact the aesthetic properties. For example, Anatase or Rutile T1O2 types used in polymer compounds for fiber application can influence the fiber color as being more blue or white. The type and amount of T1O2 can impact the ability to dye the fibers; therefore, the dye methods may differ accordingly. Typical fibers can have 0% T1O2 which are considered a "bright" luster, and 0.32% which is considered a "dull" luster. In carbon based anti-static fibers, the non-conductive polymer component can include up to 30% T1O2.

Past development efforts have been focused on either meeting surface resistance test requirements or designed for light colored fabrics where surface resistance testing is not required. One can say that meeting these two separate preferences have been mutually exclusive in past development efforts. Hence, a light colored fabric to meet surface resistance requirements has not heretofore been seen. Traditionally, most anti-static fibers developed for lighter colored fabrics have the conductive component located in the fiber's core. In many of these cases, the conductive core is also produced from a non-carbon material, such as a T1O2 and tin oxide compound. The purpose for these practices is to hide or camouflage the carbon component, therefore making the fiber lighter in color. As the conductive core material is insulated by a polymer sheath, these products do not perform well where surface resistance measurements are required. The polymer sheath prevents the test meter probes from making the appropriate contact with the conductive material.

Although they cannot meet surface resistance requirements, these type of products can effectively dissipate static charges. More suited test methods for core conductor products include Static Decay Methods EN 1149-3 and Fed Std 191 Method 5931. Products developed for surface resistance requirements traditionally are dark or near black in color. These type products can usually meet

requirements in test methods such as AATCC Method 76, but due to their dark color, these type fibers are not typically used in light colored fabrics with certain aesthetic preferences.

The art is replete with patents, applications and references to fibers coated with electro-resistant components, core/sheath type fibers to improve resistivity of fibers, and carbon black used in conjunction with polymeric and natural fibers to improve resistivity. Representative examples are seen in the following US patents: 5,744,090; 5,820,805; 6,083,562; 7,767,298; and 7,824,769. In some cases, T1O2 has been used as a delustrant together with carbon black, as can be seen in US patents: 3,969,559 and 4,248,934. These references do not disclose solutions to solve the problem of meeting surface resistance requirements with light colored fibers or resultant fabrics. There continues to exist a need for a fabric for garments wherein the electrical resistance is low and the ability to permanently maintain a light color is present. An objective of the present invention is a "dual purpose" product that meets surface requirements and customers' expectation in light colored fabrics.

SUMMARY OF THE INVENTION

Existing No-Shock® products, as sold by Ascend Performance Materials, are bi-component fibers that have two components within the same fiber/filament. In most cases, all No-Shock® fibers/filaments within a specific product are the same, therefore each fiber/filament contains the same materials and has the same bi-component configuration/cross section. While the ingredients are similar, their ratio in-use differ slightly based on functional needs by application, and the raw materials are extruded into a multitude of cross sections specified by No-Shock® fibers/filaments end uses. Any No-Shock® surface-stripped filament is, by its nature, black in color and therefore limited in its uses. While many bicomponent fiber products are known in the art, disclosed herein is a novel product comprising a melt spun, bicomponent product having high loadings of carbon black and T1O_2, respectively, and yet retaining a light colored appearance and a standard accepted in the industry for electrically resistant fiber products.

Products of the invention exhibit a surprising combination of whiteness and anti-static properties. The results are especially surprising in view of the fact that the non-conductive, fiber-forming component is heavily loaded with T1O₂, an insulating material. In spite of the high delusterant content, the anti-static bicomponent fibers of the invention provide low surface resistance values, as well as very short static decay times and decling times, as is seen in the examples which follow.

In one aspect, there is provided in accordance with the present invention an anti-static bicomponent fiber of light color comprising an electrically conductive component and an electrically non-conductive fiber-forming component, wherein:

(a) the electrically conductive component comprises a matrix polymer and carbon black; and

(b) the electrically non-conductive fiber-forming component comprises a fiber-forming polymer delustered with T1O2, the T1O2 being present in an amount of at least 2 wt.% based on the weight of the electrically non-conductive fiber-forming component, said electrically non- conductive fiber-forming component defining an elongate fiber structure of the anti-static bicomponent fiber, the anti-static bicomponent fiber being further characterized in that the electrically conductive component is arranged in at least 3 separate electrically conductive surface stripes extending along the length of the fiber, said stripes being spaced apart from each other over the outer periphery of the anti-static bicomponent fiber and separated by the electrically non-conductive fiber-forming component, the surface stripes being operative to provide anti-static properties to the anti-static bicomponent fiber.

The present application is thus directed, in part, to a bicomponent fiber comprising two components, wherein one component contains an electrically conductive component, and the second component contains a non-electrically conductive component. In various embodiments, the anti-static product is characterized in that a. the conductive component comprises a polymer having at least three carbon black surface stripes, having greater than 2 wt.% carbon black; preferably in the range of 2-30 wt.%, and more preferably about 15-25 wt.%, with a greater preference to 25 wt.% carbon black content; b. the non-conductive component comprises a polymer delustered with T1O2 at greater than 2 wt.% Ti02 content; preferably in the range of 2-30 wt.%, and more preferably about 15-25 wt.%, with a greater preference to 25 wt.% T1O2 content; the product having the following properties: electrical resistance of less than lxlO¹⁰ ohms/cm in accordance with Test Method A using a Keithly 6517 Electrometer; elongation of less than 85%, in accordance with ASTM D 2101 -72 Standard Test Methods for Tensile Properties os Single Man-made Textile Fibers Taken from Yarns and Tows; and having a L* target color value of greater than 50, and in the range of about 50-60 L*, with a preference of color value of 55.

The inventive light colored polymer of the conductive and non-conductive fiber consists of one or more polyester, polyamide, polyalkene, polyacrylic, with a preference towards Nylon-6 and/or Nylon-66. In an embodiment, one component contains about 70-98 wt.% Nylon-66 doped with about 2-30 wt.% Ti0₂, and the other component comprises about 2-30 wt.% of Nylon-6/carbon black

composition to make the remaining percentage of the product. The product may gave a denier range in accordance with test method ASTM D 1577 of greater than 15, with surface stripes of Nylon-6/carbon black, preferably in the range of about 15-100, more preferably about 15-20, with a final preference for the product having a denier of about 20. The product (fiber) has a preferred electrical resistance in the range of about 5xl 0⁶ ohms/cm to less than about 5xl0⁹ ohms/cm in accordance with Test Method A using a Keithly 6517 Electrometer. More generally, the fiber has an electrical resistance of about 10⁶ ohms/cm to less than about 10¹⁰ ohms/cm, typically in the range of from about 10⁶ ohms/cm to about

10⁷ ohms/cm. The product has the conductive component configuration of 3 or more surface stripes of carbon black, typically 3 to 5 and is preferably prepared by a conjugant / melt extrusion spinning process.

The inventive fiber product is essentially material agnostic, meaning numerous types of polymers can be employed herein, alone or extruded, blended, or twisted together, and yet maintain the color - electrical resistance properties. It has been found that there is a range of carbon loading and T1O2 content leading to the properties disclosed. The resulting fiber product can be made in various denier values to accommodate the desired application and is generally useful in textiles, as described herein. While the targeted application for use is consumer wear and, in particular, intimate apparel, it is anticipated that customized fiber product can be constructed to meet the needs for industrial applications, as well (e.g., dust repellency for clean or ultra clean rooms). The inventive fiber is incorporated into a variety of textile products, including multi-filament yarn, fabrics and so forth.

BRIEF DESCRIPTION OF DRAWINGS

The features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. Embodiments of the present invention will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the scope of the claims, wherein like designations denote like elements, and in which: Figure 1 is a perspective illustration of an anti-static bicomponent fiber of the invention having 3 carbon black surface stripes;

Figure 2 is an illustration of a cross section of the anti-static bicomponent fiber of Figure 1 having the carbon black surface stripes;

Figure 3 is a photomicrograph of a cross section of an anti-static bicomponent fiber of the invention having the carbon black surface stripes; and

Figure 4 is a photograph showing a standard fiber bobbin on the right (darker) side and the inventive (lighter) fiber bobbin on the left side of the Figure.

Those with ordinary skill in the art will appreciate that the elements in the Figures are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some of the elements in the Figures may be exaggerated, relative to other elements, in order to improve the understanding of the present invention.

There may be additional components described herein that are not depicted on one of the described drawings. In the event such a component is described, but not depicted in a drawing, the absence of such a drawing should not be considered as an omission of such design from the specification. The present invention will be described relative to the requirements suitable for intimate apparel, but it is known to those skilled in the art that the fiber product may be modified to accommodate the desired needs of the user. Hence, without limitations, industrial apparel, safety apparel, and children's wear, among a few applications, are examples suitable for use of the subject fibers. The only limitation being present herein is that the fiber and resulting garment be resistant to surface charges as described herein.

DETAILED DESCRIPTION OF EMBODIMENTS

As used in the specification and claims, the singular forms "a", "an" and

"the" include plural references unless the context clearly dictates otherwise. For example, the term "an article" may include a plurality of articles unless the context clearly dictates otherwise.

An "anti-static bicomponent fiber" refers to a fiber with 2 or more distinct components defining at least one electrically conductive component and at least one relatively non-conductive component.

As used herein, the terminology "electrically conductive component" means a component with a lower resistivity than an "electrically non-conductive fiber-forming component". "Conductive" and like terminology refers to anti-static compositions and more conductive compositions such as electrostatic dissipative (ESD) compositions having a volume resistivity of somewhat less than about 10¹² omhs/cm. Anti-static compositions generally have volume resistivities between about 10^s ohms/cm to somewhat less than 10¹² ohms/cm while ESD compositions have volume resistivities in the range of 10² ohms/cm to 10^s ohms/cm. Electrically non-conductive compositions generally have volume resistivities of greater than 10¹⁰ or 10¹² ohms/cm, but higher than an electrically conducting component in any event. The electrically conductive component generally has a volume resistivity in the range of from about 10² ohms/cm to less than 10¹⁰ ohms/cm, depending upon loading of the carbon black, while the associated non-conductive component has a higher volume resistivity. The overall resistivity of the fiber reflects the resistivity of the components.

"Consisting essentially of and like terminology refers to the recited components and excludes other ingredients which would substantially change the basic and novel characteristics of the composition, article or process. Unless otherwise indicated or readily apparent, a composition or article consists essentially of the recited or listed components when the composition or article includes 90% or more by weight of the recited or listed components. That is, the terminology excludes more than 10% unrecited components.

"Fiber" and like terminology refers to filament (continuous) fibers and staple fibers. Most natural fibers such as cotton and wool, are staple fibers.

Synthetic fibers, such as nylon and polyester, are considered filament fibers. The natural fiber silk is also a filament fiber, but when filament fibers are cut short, they are considered staple fibers. Staple fiber lengths are typically less than 7.5 cm (3 inches)

The polymer of the conductive and non-conductive fiber may consist of one or more Nylon-6, Nylon-66, polyester, polyamide, polyalkene and/or polyacrylic. The preferred polymers are Nylon-6 and Nylon-66. The bicomponent fiber product has one component comprising about 70-98 wt.% of the fiber made up of Nylon-66 doped with about 2-30 wt.% T1O2, and another component comprising about 2-30 wt.% of the product made up of Nylon-6/carbon black composition. The denier range for the resulting bicomponent product is about 15- 100 denier with surface stripes of Nylon-6/carbon black, with one preferred range of about 20-25 denier for single and double filament products. It has been found to be light in color in spite of the high loadings of carbon black, having an L* target color value of 55. The fiber resistivity of this light-colored fiber product is in the range of about 5xl 0⁶ ohms/cm to less than about 5xl0⁹ ohms/cm. Fabric testing methods include the following, which may be used at the user's desire: Static Decay Methods - EN 1149-3, Surface Resistance AATCC Method 76, Static Decay Methods - Fed Std 191 Method 5931 ; electrostatic clinging of fabrics, Fabric-to-Metal Test AATCC Method 1 15. An elongation maximum of about 85% is achieved with the present inventive fiber product, and it has been found to have at least 3 or more stripes of carbon black to achieve the preferred electrical resistance.

The polymer components of the constituents can be composed of any suitable melt spun or thermoplastic fiber-forming polymers and copolymers. By

"fiber-forming" is meant the property of linear, high molecular weight polymers making such capable of being formed into fibers of useful strength and toughness.

Suitable polymers include polyolefins such as polyethylenes and poly propylenes; polyamides and copolyamides (nylons), such as polyhexamethylene adipamide (Nylon-66), polymeric ε-caprolactam (Nylon-6), polyaminoundecanoic acid, polymers of bis-paraaminocyclohexyl methane and undecanoic acid; polystyrenes; polyesters, such as those of polymeric hydroxy carboxylic acid esters and of terephthalic or isophthalic acids and lower alkylene glycols such as ethylene glycol and tetramethylene glycol; polyurethanes; polyureas; polycarbonates; polyvinyl halides; polyvinylidene halides, etc. For better adherence of the constituents in the filament, it is preferred that the polymers of both constituents be selected from the same polymer genus. Polymers may be modified by incorporation of delustrants, dye-enhancing materials, dye-resisting materials, etc. The preferred polymers are polyesters, Nylon-6 or Nylon-66, with Nylon-66 containing no more than about 30 wt.% delustrant, T1O₂, so as to produce the light colored resulting yarn.

The carbon black compounded in the polymer of one of the constituents must be of the electrically conductive type and should retain its conductive nature in the textile article formed at least in part from the biconstituent filaments. By "electrically conductive carbon black" is meant any carbon black which has a specific resistivity of less than 200 ohm/cm as measured by ASTM Method D991- 68. A resistance of less than lxlO⁸ ohms/cm is preferred. The carbon black may be dispersed in the polymer forming the conductive constituent of the

biconstituent filament by known mixing procedures, provided that an end result of at least 3 stripes are found on the single fiber formed. Excessive shearing of the black is to be avoided in that the conductivity of the black can be substantially reduced thereby. Sufficient dispersion of the black in the polymer should be accomplished under conditions that result in a minimum reduction in the conductivity character of the black.

The amount of carbon black compounded in the polymer of one of the constituents should only be sufficient to impart the desired low resistance to the electrically conductive component. It is understood in the art that various definitions of "conductive" exist. Herein, the term "conductive" is intended to mean materials that enable moderate levels of electric current flow. The biconstituent filament is preferably round in cross section, although multi-lobal cross section may be desired for certain end uses. It is, however, important that the cross sectional area of the conductive constituent comprises only a minor amount of the total cross sectional area of the filament. Cross sectional areas of the constituents are directly translatable into volumes of the respective constituents composing the filament. The cross sectional areas of the conductive constituent should compose about 1 to 30 percent of the cross sectional area of the filament. Preferably the percent is 3 to 12. Below 1 percent, the effectiveness of the static electricity dissipation may be too low for many uses; and with such a low volume of such conductive constituent, it is difficult to assure that the constituent is not completely enveloped with the non-conductive polymer component. When the percent of cross sectional area of the conductive constituent exceeds 30, adherence of the constituent is reduced, as well as the tensile strength of the filament, since most of the tensile strength of the filament is derived from the non-conductive constituent. No-Shock® type fibers and most anti-static competitive products typically have low tenacity values, and often in the range of about 2.0- 4.0 g/d.

The interface of the two constituents in the subject invention should be curvate. The cross section of the non-conductive constituent normally has a shape such that the non-conductive constituent partially encapsulates the conductive constituent. Providing such a cross section configuration ensures better adherence between the two dissimilar constituents and reduces the noticeable presence of the black component on the surface of the filament to a mere stripe of low visibility. The non-conductive constituent partially encapsulates the black-containing constituent in an amount of at least 50 percent. Preferably, the average percent encapsulation should be between about 66-95. By "percent encapsulation" is meant the percent of extrudate periphery of the stripes occupied by the non- conductive constituent, as hereinafter described and illustrated.

The subject invention is not directed towards a sheath-core type of fiber or technology, as these types of fibers have the conductive component sheathed within the non-conductive polymer, making the conductive portion not be at the surface. The invention is directed towards a surface conductive component and technology.

The following test methods may be employed in connection with determining properties of the invention anti-static bicomponent fibers and fabrics.

TEST METHODS

Unless otherwise specified, any industry standard test method refers to the version in effect as of April 1 , 2017 and conditioning and testing is conducted at 50% RH and 21 °C, allowing for equilibration. At least 3 specimens of each sample are tested, unless otherwise stated. Fiber Resistivity is measured by Test Method A: fiber or yam resistivity is measured using a Keithley Model 6517 Electrometer. The apparatus and procedure are as follows:

APPARATUS

1. Keithley Model 6517 Electrometer.

2. Shielded test enclosure with Semi-automatic clamping device.

3. 100 mega ohm resistor.

4. Windows software for operating the electrometer. SETUP 1. Electrode spacing is 7.5 cm.

2. Set air pressure on fixture cylinder to 30 psi with air stripper on.

3. The Configuration is set by the Windows program. PROCEDURE

1. Double click the Resistance Meter Icon to open the application.

2. There will be a "Calibrate" box and "Enter New Merge" on the left side of the screen. Click the "New Merge Retrieve Results" box. You can enter a new merge or retrieve information (on results already performed you can not change any pre-existing information).

3. Open the cover door, place the 100 ΜΩ resistor between the clamps, and the flip switch to close clamps. Note: the pressure gauge should be set at 30 psi.

4. When the resistor is in place, close the door and click "Calibrate". If the calibration is within limits, a "Calibration is in Limits" message box will pop up. Click "Okay" and begin testing. If the calibration is out of limits, click "Okay", and check the resistor to be sure it is making good contact, and then recalibrate.

5. Resistor reading should be between (9.8 x 10⁹ +/- 0.2) Note: Calibration will print out on result sheet when testing is complete.

6. Open the door and remove the resistor and close the door back.

7. Open the cover, thread fiber through pretension guides and into the aspirator. Make sure the filaments or yarn is over the clamps. If the specimen is set up already, tie in the yarn.

8. Close the cover.

9. Lift up the air knob to the left of table. Strip for 20 to 30 seconds.

10. Stop the yarn before flipping switch to close clamps. Yarn may require a little twist. Specimen should be centered between clamps with no slack.

11. Turn the air stripper off. 12. There are three boxes at the bottom of screen "Cancel Testing", "Read Resistance", and "Recheck".

13. Click on "Read Resistance". Note: Each bobbin is routinely run only once, some bobbins require additional checks. Check the sample schedule, SI, or RSA for testing specifications. The results will display in the white field on the right of the screen. If the result is out of spec, the system will highlight the result. Out of spec print in bold.

14. Repeat until all bobbins are tested.

15. Click in the box in front of the reading that is out of spec, air strip the bobbin, reload the same bobbin, and click on "Recheck".

16. Repeat steps 7-15 for each bobbin that is to be tested.

Fiber Tensile Properties-ASTM D 2101-72 Standard Test Methods for

Tensile Properties of Single Man-Made Textile Fibers Taken from Yarns and Tows is used to measure fiber tensile properties.

Surface Resistance-AATCC Method 76 is used to measure the surface resistance of fabrics. For each sample, at least 3 specimens are averaged; only the lower value is reported for product plate testing. Samples are conditioned and tested at 50% RH and 21°C. Surface resistance of fabrics is reported in ohms per square.

Static Decay Methods - Fed Std 191 Method 5931 is used for measuring the dissipation of electrostatic charge from the surface of fabrics. This method can be used for either surface conducting or core conducting fibers. After the full charge is applied and removed, the fabric must discharge within < 0.5 seconds. Test Method EN 1149-3 may also be used for measuring the dissipation of electrostatic charge from the surface of fabrics. This method can be used for either surface conducting or core conducting fibers. After the full charge is applied and removed, the fabric must discharge within < 4.0 seconds.

Electrostatic Clinging of Fabrics: Fabric to Metal - AATCC Method 115 is used for evaluating the relative clinging tendency of certain fabrics due to electrostatic charge generation. The test integrates the effect of fabric weight, stiffness, construction, surface character, finish application and other fabric parameters which affect the tendency of fabrics to cling. Only average values are reported. Testing and conditioning may be conducted at 50% RH and 21°C.

Color Test for L* Value-L* is determined in accordance with the CIELAB 1976 L*a*b* colorimetric system. L* within the full spectrum of color testing, the 3^rd axis measures the whiteness of materials. The L* value measures the relative difference between black = 0 and white = 100. A Byk-Gardner Color Sphere Color System is used, specifically a utilizing a Byk-Gardner model TCS 8800 Colorimeter or equivalent. Measurements are made at room temperature (i.e., at about 23°C) using a compression cell with 5 gram specimens of filament fiber therein, air fluffed to form an entangled substrate for analysis. Testing is performed on duplicate specimens.

Denier (ASTM D 1577) is the linear density of a fiber as expressed as weight in grams of 9000 meters of fiber. Usually, the fiber is conditioned at 55±2% relative humidity, and 75°±2° F on the package for a specified period, usually 24 hours when the monofilament has aged more than ten days since being made. A 0.9 meter sample of monofilament is weighed and denier is calculated as the weight of a 9000 meter sample in grams. Denier times (10/9) is equal to decitex (dtex). Denier and tenacity tests performed on samples of staple fibers are at standard temperature and relative humidity conditions prescribed by ASTM methodology. Specifically, standard conditions mean a temperature of 70 +1-2° F. (21 +/-\° C.) and relative humidity of 65% +1-2%. 1. FIBER CONSTRUCTION AND PREPARATION

Referring to Figures 1 and 2, there is shown an anti-static bicomponent fiber 10 comprising an electrically conductive component 12 and an electrically non-conductive fiber-forming component 14. The electrically conductive component includes a matrix polymer loaded with carbon black in order to provide conductivity. Electrically non-conductive fiber-forming component 14 comprises a polymer such as a nylon which is delustered with T1O2. T1O2 is present in an amount of at least 2 wt.% based on the weight of the electrically non-conductive fiber-forming component 14. It is appreciated that the electrically non-conductive component 14 is the majority of material (more than 50 wt.% of the fiber) and that it defines an elongate fiber structure 16 generally indicated in Figure 1. Anti-static bicomponent fiber 10 is further characterized in that electrically conductive component 12 is arranged in 3 separate, equally spaced as shown, electrically conductive stripes 18, 20 and 22 extending along a length, L, of anti-static bicomponent fiber 10. Stripes 18, 20 and 22 are spaced apart from each other over an outer periphery 24 of fiber 10 such that outer surfaces 30, 32 and 34 of stripes 18, 20 and 22 are exposed and the inner portions 36, 38 and 40 are at least partially and preferably mostly encapsulated by electrically nonconducting component 14 (Figure 2). The stripes are thus separated by electrically non-conducting component 14.

Anti-static bicomponent fibers 10 are generally uniform in cross section along their length. The degree of encapsulation of electrically conductive component 12 is conveniently calculated as a percentage by summing the cross section perimeter lengths of the conductive stripes in contact with electrically non- conductive, fiber-forming component 14, dividing by the sum of the cross section perimeter lengths of the stripes (both the encapsulated and unencapsulated portions) and multiplying by 100%.

The anti-static fibers of the invention are preferably made by utilizing a conjugant melt extrusion spinning process as is known in the art and described in the references enumerated above. Note, particularly, United States Patent No. 3,969,559. Spinning of anti-static biconstituent filaments is suitably accomplished by melt co-extruding a plurality of different polymer compositions in a spinning apparatus provided with coextrusion capability and a spinnerette plate adapted to conjugate the streams into the desired structure. The spinnerette typically employs a plurality of converging branched capillaries of suitable size and geometry which conjugate the components into the desired structure as it is extruded.

Figures 1 and 2 illustrate a single filament which was produced by bringing 2 melt streams together in a conjugant melt extrusion spinning process. In any embodiment, the anti-static bicomponent fibers of the invention contain multiple, at least 2, but preferably 3 or more surface stripes. The black stripes contain carbon black. The electrically non-conductive component is white with about 25 wt.% T1O2 compounded with Nylon-66. Upon unwinding the fiber from the bobbin, both the dark and light colors are contained within the same filament.

Figure 3 illustrates a typical cross section of multiple filaments. Note the 3 stripes of carbon on the perimeter of the filament. It has been found that a higher number of stripes spaced an equal distance apart results in lower resistance measurement values. The important value in this new product is delivered by a combination of raw material selection and the carbon stripe configuration within the fiber.

Figure 4 is a photograph of bicomponent fiber bobbins comparing a typical existing multiple stripe product on the right side with the inventive product on the left side. Although the resistance values are somewhat similar, the color is significantly different. While not being tied to theory, it is believed that the heavy loading of Ti0₂ is sufficient to camouflage the heavy loadings of the carbon black without impacting the dyeability of the fiber. It is seen hereinafter that the invention fiber exhibits surprisingly low surface resitance values when incorporated into a fabric, notwithstanding the fact that it is highly loaded with T1O₂ , an insulative material.

2. FIBER EXAMPLES

20 denier/2 filament products with 3 surface stripes containing between 7 and 15% carbon were manufactured using a conjugate melt-spinning process. Three (3) versions were produced. It was found that the lightest colored product has a high resistance value suitable for various applications. It was found that the product with the lowest resistance has the darkest color. When T1O₂ (Rutile) was employed as the delustrant at about a 10% composition, it was found to provide a favorable chance for multi-function purposes. The T1O₂ (Anatase) at

compositions of 7% and 15%, respectively, resulting in darker blue fibers, was somewhat expected due to the darker color type of T1O2. The T1O2 (Rutile) resulted in a much lighter product with similar resistance to Ascend Performance Material's currently most conductive black product, (see Example 3B) shown as dark fiber on bobbin in Figure 4.

These examples used Nylon-66 as both the matrix polymer and the fiber-forming polymer. Nylon-66 polymer chips of cube-like shape were prepared using a conventional polymerization autoclave, quenching device and cutter. The chips were suitable for melt spinning into filaments. Nylon-66 polymer so produced was loaded with electrically conductive carbon black sold under the trademark Vulcan C available from Cabot Corp. of Boston, Mass. The carbon black had the following reported analysis:

Fixed carbon 98.5%

Volatiles 1.5%

Particle size 23 millimic rons Surface area 125 sq.meters/gram

Electrical resistivity very low The carbon black was dispersed in the polymer by the following procedure. Predetermined amounts of nylon and carbon black are fed to a No. 6 Ferrel Continuous Mixer operated in the normal manner for compounding carbon black into a high molecular weight linear polymer. The output of the mixer is fed to an extruder fitted with a multi-strand die. The extruded rods having a representative diameter of about 3 mms. were cut into small cylinders having an average length of about 3-6 mms.

The two polymer compositions were spun into an anti-static bicomponent fiber having the geometry shown in Figures 1-3 using a conjugate melt-spinning process.

3. COMPARATIVE EXAMPLES

The information in Table 1 describes existing Ascend Performance Material No-Shock® fibers having 3 surface stripes and no T1O2 delustrant.

These are shown for comparative reasons. The fibers having similar carbon black content were black in appearance and hence unsuitable for use for light-colored fabrics or other textiles as seen in Figure 4.

Table 1 - Comparative Products

Table 1 Terms:

Spun (POY) Continuous Filament Nylon No-Shock® Products: Carbon

Conductive, Polyamide (Nylon) Substrates

Drawn (FDY) Continuous Filament No-Shock® Products: All Conductive Media, All Polymer Substrates All products are bicomponent fibers with the conductive material dispersed in a polymeric matrix (not suffused or coated). Color shades and description are for comparison only. 4 FABRIC CHARACTERISTICS

A knitted fabric with 20 denier/2 filament product that has 3 surface stripes containing between 7 and 15% of an electrically conductive component was produced. Results are shown in Tables 2 and 3 and below. In Tables 2 and 3, fiber 4A is a bicomponent fiber with a conductive core and a non-conductive sheath wherein the sheath was delustered with about 4% T1O2. Fiber 4B is a

bicomponent fiber with a conductive core and 24% T1O2 in the non-conductive sheath. Fibers 4C and 3B are bicomponent fibers having the geometry shown in Figures 1 and 2 having respectively 24% T1O2 in the electrically non-conductive component (4C) and no T1O2 in the electrically non-conductive fiber-forming component (3B). The control fiber was formed from a non-conductive component consisting mostly of Nylon-66.

The invention fabric showed lighter color than with the fabric made from fiber 3B (Shown as dark fiber on bobbin in Figure 4). The invention fabric also showed similar color on the fabric compared to products including fiber 4A but worse compared to fiber 4B. Samples incorporating anti-static fiber with the construction of Figures 1 and 2 showed much lower surface resistivity than both fabrics where carbon is in the center of the ant-static fibers. Compared to the control fabric which does not contain anti-static yarn, fabrics had static decay time 0.01 sec according to standard Fed Std 191 Method 5931. Fabrics also showed no- clinging according to AATCC1 15 Test method.

Despite of its high T1O2 loading, fabrics produced with the claimed technology (3A and 3B) showed similar Static Decay performance as the currently available No-Shock® yams. Samples also showed -800 improvement over

Control samples. Surface resistance of the fibers also showed improvement over control samples. The invention filaments handle the knitting process nicely.

Table 2 - Fabric Properties

Too high to measure by technique employed

Table 3 - Fabric De-Cling Properties

It is appreciated from Tables 2 and 3 that the anti-static bicomponent fibers of the invention provide surprising properties to the fabric. In particular, the invention provides surface resistance even lower than dark colored fibers without T1O2 in the non-conductive component and very short decling times. The results are particularly unexpected in that T1O2 loaded materials are expected to exhibit higher surface resistance. 5. FIBER BLENDS

If so desired, the anti-static bicomponent fibers of the invention may be blended with non-conducting fibers to prepare yams suitable for apparel and carpets. The invention bicomponent fibers are particularly suitable for being added in minor amounts to a larger bundle of normal non-conductive synthetic filaments or fibers prior to spinning or during drawing or drawtexturing thereof. The bicomponent fibers in filament fiber form can be cut to desired staple lengths and blended with non-conductive staple fibers using conventional means. The blended fibers can then be spun into yarn having anti-static qualities. The strands of the present invention can be used alone or preferably intermingled with other strands in the production of suitable textile articles produced by standard weaving, tufting, knitting, flocking, netting, braiding and other techniques. As low as about 0.1 wt.% of the fabric may be composed of the bicomponent fibers of the invention with the remainder of the fabric comprising any of the natural or man- made fibers and filaments; and yet suitable static dissipation is attained. Ordinarily the fabric need not contain more than 10 wt.% bicomponent fiber. Examples of fibers and filaments advantageously combined with the anti-static bicomponent fibers of the invention are those made from olefin polymers, acrylonitrile polymers, nylon polymers, aramid polymers, polyethylene terephthalate polymers, as well as those of cotton and wool.

The anti-static bicomponent fibers of the invention are conveniently and advantageously incorporated in continuous filament carpet yarn before drawtexturing thereof without the need of taking expensive precautions to assure non-breakage of the anti-static bicomponent fibers. Various drawtexturing techniques can be used. For example, one or more undrawn anti-static

bicomponent fibers of suitable individual denier (1 -30 drawn denier) can be directed to a yam feeding means supplying carpet yam of 800-4000 ultimate denier, for example, to drawtexturing devices of various kinds. The drawtexturing devices include hot-draw-gearcrimpers, draw-falsetwisters, draw-stuffer boxes either mechanically fed or hot fluid jet fed, and draw jet aspirating devices. Spinning and drawtexturing can be coupled in one continuous operation.

While the invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those of skill in the art. Such modifications are also to be considered as part of the present invention. In view of the foregoing discussion, relevant knowledge in the art and references discussed above in connection with the foregoing description including the Detailed Description and Background of the Invention, the disclosures of which are all incorporated herein by reference, further description is deemed

unnecessary. In addition, it should be understood from the foregoing discussion that aspects of the invention and portions of various embodiments may be combined or interchanged either in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention.

Claims

WHAT IS CLAIMED IS:

An anti-static bicomponent fiber comprising an electrically conductive component and an electrically non-conductive fiber-forming component, wherein:

(b) the electrically non-conductive fiber-forming component comprises a fiber-forming polymer delustered with T1O2, the T1O2 being present in an amount of at least 2 wt.% based on the weight of the electrically non-conductive fiber-forming component, said electrically non- conductive fiber-forming component defining an elongate fiber structure of the anti-static bicomponent fiber, the anti-static bicomponent fiber being further characterized in that the electrically conductive component is arranged in at least 3 separate electrically conductive surface stripes extending along the length of the fiber, said stripes being spaced apart from each other over the outer periphery of the anti-static bicomponent fiber and separated by the electrically non-conductive fiber- forming component, the surface stripes being operative to provide anti-static properties to the anti-static bicomponent fiber.

The anti-static bicomponent fiber according to Claim 1, having from 3-5 separate electrically conductive surface stripes extending along the length of the fiber, said stripes being spaced apart from each other over the outer periphery of the anti-static bicomponent fiber and separated by the electrically non-conductive fiber-forming component, the surface stripes being operative to provide anti-static properties to the anti-static bicomponent fiber.

The anti-static bicomponent fiber according to Claims 1 or 2, wherein the electrically conductive surface stripes are equally spaced over the outer periphery of the fiber.

4. The anti-static bicomponent fiber according to Claims 1-3, wherein the

electrically conductive surface stripes are at least partially encapsulated by the electrically non-conductive fiber-forming component therebetween.

5. The anti-static bicomponent fiber according to Claim 4, wherein the

electrically conductive surface stripes are at least 50% encapsulated by the electrically non-conductive fiber-forming component therebetween.

6. The anti-static bicomponent fiber according to Claim 4, wherein the

electrically conductive surface stripes are at least 75% encapsulated by the electrically non-conductive fiber-forming component therebetween.

7. The anti-static bicomponent fiber according to any of Claims 1 to 6, wherein the matrix polymer of the electrically conductive component and the fiber-forming polymer of the electrically non-conductive fiber-forming component are the same polymer.

8. The anti-static bicomponent fiber according to any of Claims 1 to 6, wherein the matrix polymer of the electrically conductive component and the fiber-polymer of the electrically non-conductive fiber-forming component are different polymers.

9. The anti-static bicomponent fiber according to any of Claims 1 to 8, wherein the matrix polymer of the electrically conductive component and the fiber-forming polymer of the electrically non-conductive fiber-forming component are selected from polyester polymers, polyamide polymers, polyalkylene polymers and polyacrylic polymers.

10. The anti-static bicomponent fiber according to any of Claims 1 to 9, wherein the matrix polymer of the electrically conductive component and the fiber-forming polymer of the electrically non-conductive fiber-forming component are polyamide polymers.

11. The anti-static bicomponent fiber according to Claim 10, wherein the matrix polymer of the electrically conductive component is nylon-6 and the fiber-forming polymer of the electrically non-conductive fiber-forming component is nylon-66.

12. The anti-static bicomponent fiber according to any of Claims 1 to 11, having a single filament denier (dpi) of from 2 to 30.

13. The anti-static bicomponent fiber according to any of Claims 1 to 11, having a single filament denier (dpi) of from 5 to 20.

14. The anti-static bicomponent fiber according to to any of Claims 1 to 11, having a single filament denier (dpi) of from 7.5 to 15.

15. The anti-static bicomponent fiber according to any of Claims 1 to 14, wherein the electrically conductive component is present in an amount of from 2 wt.% to 30 wt.% based on the weight of the fiber and the non-conductive fiber- forming component is present in an amount of from 70 wt.% to 98 wt.% based on the weight of the fiber.

16. The anti-static bicomponent fiber according to Claim 15, wherein the

electrically conductive component is present in an amount of greater than 5 wt.% based on the weight of the fiber.

17. The anti-static bicomponent fiber according to Claim 16, wherein the

electrically conductive component is present in an amount of from 7.5 wt.% to 15 wt.% based on the weight of the fiber.

18. The anti-static bicomponent fiber according to any of Claims 1 to 17, wherein T1O2 is present in an amount of from 2 wt.% to 30 wt.% based on the weight of the electrically non-conductive fiber-forming component.

19. The anti-static bicomponent fiber according to Claim 18, wherein T1O2 is present in an amount of greater than 10 wt.% based on the weight of the electrically non-conductive fiber-forming component.

20. The anti-static bicomponent fiber according to Claim 19, wherein T1O2 is present in an amount of greater than 15 wt.% based on the weight of the electrically non-conductive fiber-forming component.

21. The anti-static bicomponent fiber according to Claim 20, wherein T1O2 is present in an amount of greater than 20 wt.% based on the weight of the electrically non-conductive fiber-forming component.

22. The anti-static bicomponent fiber according to any of Claims 1 to 21, wherein carbon black is present in an amount of from 10 wt.% to 50 wt.% based on the weight of the electrically conductive component.

23. The anti-static bicomponent fiber according to Claim 22, wherein carbon black is present in an amount of from 25 wt.% to 40 wt.% based on the weight of the electrically conductive component.

24. The anti-static bicomponent fiber according to any of Claims 1 to 23, wherein the anti-static bicomponent fiber exhibits an electrical resistance of less than 10¹⁰ ohms/cm as measured by Test Method A using a Keithly 6517

Electrometer.

25. The anti-static bicomponent fiber according to Claim 24, wherein the anti-static bicomponent fiber exhibits an electrical resistance of from 5xl0⁶ ohms/cm to 5xl0⁹ ohms/cm as measured by Test Method A using a Keithly 6517 Electrometer.

26. The anti-static bicomponent fiber according to Claim 25, wherein the

anti-static bicomponent fiber exhibits an electrical resistance of from 10⁶ ohms/cm to 10⁷ ohms/cm as measured by Test Method A using a Keithly 6517 Electrometer .

27. The anti-static bicomponent fiber according to any of Claims 1 to 26, having a whiteness value, L*, of greater than 50.

28. The anti-static bicomponent fiber according to Claim 27, having a whiteness value, L*, in the range of from 50 to 60.

29. The anti-static bicomponent fiber according to any of Claims 1 to 28, wherein the fiber has an elongation of less than 85% as determined by Test Method ASTM D 2101-72.

30. The anti-static bicomponent fiber according to any of Claims 1 to 29,

incorporated into a multi-filament product having a denier in the range of 10 to 3000. 31. The anti-static bicomponent fiber according to Claim 30, incorporated into a multi-filament product having a denier in the range of 500 to 3000.

32. The anti-static bicomponent fiber according to Claim 30, incorporated into a multi-filament product having a denier in the range of 15 to 100.

33. The anti-static bicomponent fiber according to Claim 30, incorporated into a multi-filament product having a denier in the range of 15 to 75.

34. The anti-static bicomponent fiber according to Claim 30, incorporated into a multi-filament product having a denier in the range of 15 to 50.

35. The anti-static bicomponent fiber according to Claim 30, incorporated into a multi-filament product having a denier in the range of 15 to 25.

36. A textile product selected from carpets, woven fabrics and knitted fabrics incorporating the anti-static bicomponent fiber of any of Claims 1-29.

37. The textile product according to Claim 36, wherein the textile is a fabric exhibiting a static decay time of less than 0.1 seconds as determined in accordance with test procedure Fed Std 191 Method 5931.

38. The textile product according to Claim 37, wherein the textile is a fabric exhibiting a static decay time of less than 0.05 seconds as determined in accordance with test procedure Fed Std 191 Method 5931. 39. The textile product according to Claim 38, wherein the textile is a fabric exhibiting a static decay time of 0.01 seconds or less as determined in accordance with test procedure Fed Std 191 Method 5931.

40. The textile product according to Claim 36, wherein the textile is a fabric exhibiting a decling time of less than 6 seconds as determined in accordance with Test Method AATCC 115 for measuring clinging time of fabrics to a metal plate.

41. The textile product according to Claim 36, wherein the textile is a fabric exhibiting a decling time of less than 3 seconds as determined in accordance with Test Method AATCC 115 for measuring clinging time of fabrics to a metal plate.

42. The textile product according to Claim 36, wherein the textile is a fabric exhibiting a decling time of 0.5 seconds or less as determined in accordance with Test Method AATCC 115 for measuring clinging time of fabrics to a metal plate.

43. The textile product according to Claim 36, wherein the textile is a fabric exhibiting a surface resistance of from 10⁸ to less than 10¹¹ ohms per square as determined in accordance with Test Method AATCC 76. 44. The textile product according to Claim 36, wherein the textile is a fabric exhibiting a surface resistance of from 5x10^s to 10¹⁰ ohms per square as determined in accordance with Test Method AATCC 76.

45. The textile product according to Claim 36, wherein the textile is a fabric exhibiting a surface resistance of from 10⁹ to 10¹⁰ ohms per square as determined in accordance with Test Method AATCC 76 surface resistivity of fabrics.

46. A fiber blend comprising the bicomponent fiber of any of Claims 1 to 29 blended with non-conductive fibers and utilized to form anti-static yarn.

47. A fiber blend according to Claim 46, incorporated into a multi-filament product of any of Claims 30 to 35 to form anti-static yarn.

48. A method of making the anti-static bicomponent fiber according to any of Claims 1 to 29, comprising utilizing a conjugant melt extrusion spinning process.