CN1957121A - Bi-component electrically conductive drawn polyester fiber and method for making same - Google Patents

Abstract

This invention relates to multi-component conductive fibers (Figure 1) and their preparation method (Figure 2). The fibers contain two polyester components with a melting temperature difference of 10°C between the first and second polyesters.

Description

Two-component conductive stretched polyester fiber and its preparation method

technical field

[01] The present invention relates to electrically conductive fibers, and more particularly to bicomponent electrically conductive drawn polyester fibers.

Background technique

[02] In synthetic fibers such as polyamide fibers, polyester fibers, acrylic fibers, etc. and in some natural fibers such as wool, friction generates static electricity. This is a disadvantage of synthetic fibers, especially when these fibers are used in applications where the discharge of static electricity (characteristic shock) can have serious consequences. For example, electrostatic discharge can damage computers and other electronic equipment. In some cases, such as in a flammable atmosphere, electrostatic discharge can cause a fire or explosion. Static buildup and discharge can also affect the efficiency and productivity of fiber conversion processes such as knitting and weaving.

[03] Because of the propensity of certain fibers to generate (or not dissipate) electrical charges and because of the common use of fibers in many environments where static electricity is undesirable (such as computer room carpets, clean room clothing, uniforms, etc.), emerging A large number of solutions to static electricity generation. Typically, these methods involve rendering the fibers themselves conductive, or making articles made of fibers conductive by incorporating one or more individually conductive fibers into the article, or treating the fibers with an antistatic surface treatment Or products made of fibers. Surface preparation is usually not ideal.

[04] US Pat. Nos. 5,698,148 and 5,776,608 to Asher et al. describe conductive fibers having a sheath/core configuration for incorporation into fibrous articles such as carpets or fabrics. Conductive carbon black is blended into polyester forming synthetic thermoplastic fibers to form a conductive skin. The non-conductive core is made from the same polyester used to form the synthetic thermoplastic fibers for the conductive skin. The extruded fibers are drawn and then relaxed at a temperature above the polyester's glass transition temperature but below its melting or softening temperature.

[05] U.S. Patent Nos. 5,916,506 and 6,242,094 to Breznak et al. describe bicomponent conductive fibers in which the non-conductive first component is made of a first polymer and the conductive second component is made of a second polymer containing a conductive material. things made. The components are extruded to form a sheath/core fiber that is drawn to approximately four times its original length to increase tensile strength. This stretching results in a loss of electrical conductivity, which can be restored by heat treatment. According to Breznak, the melting point difference between the two polymers is preferably at least 20° C., so that the heat treatment does not melt the core polymer. A disadvantage of this approach is that one of the polymers needs to be heated or cooled at the spinneret to achieve a significant difference in their melting temperatures. This can undesirably lead to process interruptions and release of monomers or oligomers at the spinneret.

[06] Conductive bicomponent fibers typically exhibit a loss of electrical conductivity when stretched. This loss of conductivity is usually counteracted by post-stretching treatments or by controlling the stretching stage to minimize (but rarely reverse) this drop in conductivity. It would be desirable to develop a bicomponent conductive fiber that does not exhibit significant loss of conductivity when stretched. By eliminating the need for post-drawing treatments or other measures aimed at increasing the electrical conductivity of drawn fibers, such fibers can be produced with greater efficiency.

Summary of the invention

[07] According to one aspect of the present invention, a multicomponent conductive fiber has a first component and a second component, wherein the first component comprises a first polyester having a conductive material dispersed therein, the second component comprises a One polyester is different from the second polyester. The difference between the melting temperatures of the first polyester and the second polyester is no more than about 10°C, and preferably the two melting temperatures are within about 2°C of each other. The first polyester is generally more amorphous than the second polyester prior to drying and/or crystallization steps performed prior to fiber spinning.

[08] According to another aspect of the present invention, a method of making a drawn multicomponent conductive fiber is provided. The method includes coextruding a first component comprising a first polyester having a conductive material dispersed therein and a second component comprising a second polyester different from the first polyester . Thereafter the fibers are drawn while applying heat to form drawn fibers.

[09] In a preferred embodiment of the invention, the drawn fiber has a conductivity that is not significantly lower than that of the undrawn fiber, even without further treatment. In some cases, it was unexpected that the electrical conductivity of drawn fibers was greater than that of undrawn fibers. By avoiding the need for a separate post-stretch treatment to increase conductivity, there is potential for increased production efficiency and cost efficiency.

Brief description of the drawings

[10] Objects, features and advantages of the invention will be apparent from the following more detailed description of certain embodiments of the invention and as illustrated in the accompanying drawings, in which:

[11] FIG. 1 is a cross-sectional view of a bicomponent conductive fiber having a PBT core and a PET-based conductive component according to a preferred embodiment of the present invention; and

[12] Figure 2 is a schematic diagram of a typical spinning process for preparing the bicomponent fibers of the present invention.

Detailed description of the invention

[13] The multicomponent fiber of the present invention is made from a first polyester and a second polyester different from the first polyester. "Different from" means that the second polyester is made from a different combination of monomers than the combination of monomers used to prepare the first polyester. Commercially available polyesters can be used as each of the first and second polyesters, or those skilled in the art can easily prepare suitable polyesters. The term "multicomponent" as used herein refers to synthetic fibers having more than one polymer component, including bicomponent fibers in particular.

[14] The multicomponent fibers of the present invention can be used in a variety of applications such as textiles, industrial fabrics and carpets. It is also contemplated that the multicomponent fibers may be used in other applications, such as in nonwoven fabrics, and if further cut or processed, possibly in adhesives, intermediate layers, and the like. The fibers can also be used as staple fibers, e.g., where the fibers are spun, drawn, crimped and chopped into small discrete lengths, which can be blended with other staple fibers or can be opened and spun by themselves. into yarn.

[15] In the first component of the multicomponent fiber, the first polyester typically acts as a carrier for the conductive material. The first polyester is preferably more amorphous than the second polyester, which improves the incorporation of the carbon and also helps improve the toughness of the resulting fibers. The first polyester is preferably a polyethylene terephthalate (PET) based copolymer. If desired the polyester can be modified so that its melting temperature is closer to (or possibly the same as) the melting temperature of the second polyester. The difference between the melting temperatures of the first polyester and the second polyester is less than about 10°C, preferably less than about 5°C, even more preferably about 2°C or less.

[16] Generally, polyalkylene terephthalate or naphthalene dicarboxylate polyester can be polycondensed by terephthalic acid or its lower alkyl ester and aliphatic or alicyclic C2-C10 diol Reaction preparation. For example, polyethylene terephthalate can be prepared by polycondensation of dimethyl terephthalate (DMT) and ethylene glycol, followed by transesterification.

[17] There are several known methods of lowering the crystallinity and/or melting temperature of polyesters. For example, many polyesters are prepared using a third monomer which is a diol or a diacid (or a reactive diacid species). An example is PET modified with diols, which is commercially available as PETG. Polycycloterephthalate (PCT) modified with diols is commercially available as PCTG, while an acid-modified form of PCT is commercially available as PCTA. The acid modifier is usually a difunctional terephthalate such as dimethyl terephthalate or dimethyl isophthalate. Other difunctional acids may be used, such as adipic acid, maleic acid, different isomers of phthalic acid, and the like. The diethyl ester forms of various diacids may be preferred over the diacids themselves. Non-limiting examples of glycol modifiers include ethylene glycol, diethylene and propylene glycols, butylene glycol, cyclohexanedimethanol, and other difunctional alcohols. The level of comonomer in the polyester can vary widely, but is usually about 30 mole percent or less, usually about 1 to about 20 mole percent, usually about 5 to about 10 mole percent.

[18] A preferred PET-based polyester is available pre-blended with conductive carbon black, ex Americhem, No. 19420, melting point about 225°C. Examples of other polyesters include copolymers of terephthalic acid (TA) or dimethyl terephthalate (DMT), ethylene glycol (EOH) and cyclohexanedimethanol (CHDM), such as those found in Eastman PETG products A sort of. Other non-limiting examples of polyesters include polytrimethylene terephthalate (PTT) based polymers and polybutylene terephthalate (PBT) based polymers. Many other polyester-based carbon composites are commercially available, such as those available from Americhem under code numbers 16131 and 16222. RTP Company also has a line of carbon black filled polyester products sold under the name PermaStat(R), primarily for static control applications. These materials can be used to prepare antistatic fibers with appropriate carbon loadings. Typically, in order to achieve electrical conductivity in a carbon black filled polymer, the amount of carbon black in the polymer is such that it cannot be used by itself to form fibers. The bicomponent fibers described herein allow the use of polymers with high carbon black loadings in the fibers by using a second polymer in the filaments as a support matrix.

[19] The second polyester is generally non-conductive and may be used to form the core, for example in sheath/core type fibers. A preferred polyester for the second component is polybutylene terephthalate (PBT), which is derived from two main monomers, terephthalic acid (TA) (or dimethyl terephthalate ester (DMT)) and butanediol (BDO). See "Handbook of Thermoplastic Polymers," Fakirov ed., 2002, Wiley-VCH. PBT has a melting point of about 223°C. Other polyesters may alternatively be used in the second component, such as polytrimethylene terephthalate (PTT), copolymers based on PTT or PET, such as copolymers of PETG or PCT, or available polyesters known to those skilled in the art. Other polyesters for forming monocomponent fibers.

[20] The conductive material may be conductive carbon black or other conductive materials, such as conductive metal. Preferably, carbon black is dispersed in the first polyester. The amount of conductive material added to the first component can vary widely, but is typically from about 10 wt% to about 50 wt%, more typically from about 20 wt% to about 30 wt%.

[21] The multicomponent fibers of the present invention preferably do not exhibit a significant decrease in electrical conductivity after stretching. Preferred fibers may exhibit a 100-1000-fold drop in linear resistance after stretching. For example, when using PBT as the non-conductive polyester and Americhem 19420 as the carbon-filled polyester (25% carbon loading), it was found that the bicomponent fibers after stretching consistently exhibited a linear resistance ranging from 10 ⁸ -10 ⁹ Ω/ cm down to 10 ⁶ -10 ⁷ Ω/cm. This means that the conductivity, which has the effect of reducing electrostatic charges, is increased by about 100 times.

[22] As shown in Figure 1, the fibers are typically spun using about 11-13% of the conductive first component applied as a longitudinal strip to the non-conductive second component. Alternatively, the first and second components of the multicomponent fiber may be arranged in a sheath/core or any other suitable configuration now known or later developed for multicomponent fibers. The specific arrangement of the first and second components is not part of the present invention. Bicomponent fibers are typically spun at about 1000-2000 m/min (mpm), most typically at about 1400 mpm. Figure 2 is a schematic diagram of a typical fiber spinning process that can be used to prepare the bicomponent fibers of the present invention.

[23] The spun fibers can be stretched using any suitable equipment, such as a four-roll Erdmann stretcher. The roll temperature is preferably set above the glass transition temperature of the polyester. Typical stretching temperatures are from about 100 to about 190°C. In a preferred embodiment, the first and fourth rolls are set at 90°C, while the remaining two "drawing rolls" are set at 150°C. The fourth roll is often referred to as a relaxation roll, and is usually set at a temperature at or above the glass transition temperature (Tg) of either or both polymers. The maintenance and/or improvement of conductivity is observed over a wide range of relaxation temperatures (above and below Tg).

[24] One potential benefit from the relatively low melting temperature difference between the first polyester and the second polyester is that fibers can be prepared using common temperatures in the spin pack. In other words, neither polyester requires heating or cooling at the spinneret due to similar melting temperatures. This results in a lower incidence of process interruptions and a smoother process as less monomer or oligomers are released at the spinneret.

[25] The following examples are provided for illustrative purposes only and should not be considered as limiting the invention.

Example 1

[26] This example illustrates the preparation of bicomponent fibers in which polybutylene terephthalate (PBT) is used as the non-conductive second component and a PET-based polyester, Americhem 19420 (with 25% carbon addition) was used as the conductive first component. Extrusion conditions are summarized in the table below.

[27] Bicomponent fibers were spun using 11-13% carbon loaded polyester applied as longitudinal strips on PBT polymer. The fibers were spun at 1400 mpm to give about 45 denier fibers with a tenacity of about 1.3-1.5 g/denier. The following table summarizes the spinning conditions: 1st Godet Roller (mpm) 2nd Godet Roller (mpm) Winding Tension Winder (mpm) 140014206-7gms1425 chimney air 150cfm Finishing Goal OOY 12% oil in water 1.0-1.2% Target denier per position 45+/-2 Carbon composition percentage 11.5% Bands 3/silk

[28] measured the linear resistance of undrawn fibers to be about 10 ⁸ -10 ⁹ Ω/cm. In this example, as well as other examples herein, linear resistance was measured using a Keithley 614 potentiometer or a Keithley 6517 potentiometer/megger. Fiber samples were 7.5 cm in length. Measure 5 or 10 times and calculate the mean and standard deviation. Fiber denier is measured using a disc of known circumference and denier is expressed in grams per 9000 meters. Fiber tenacity, expressed as tenacity at break divided by denier, was measured using an Instron 8100 tensile testing machine using Instron's Merlin software.

[29] The spun fibers were drawn on a four-roll Erdmann drawer with the first and fourth rolls set at 90°C and the other two "draw rolls" set at 150°C. The stretching conditions are summarized in the table below.

set up target value unit D roller speed 1021.0 Mpm A/feed ratio 1.050 B/A ratio 1.210 C/B ratio 1.520 D/C ratio 1.000 Friction roller/D ratio 0.970 total stretch ratio 1.93 Feed roller speed 528.7 Mpm A roller speed 555.1 Mpm B roller speed 671.7 Mpm C roller speed 1021.0 Mpm Friction roller speed 990.4 Mpm A temperature 90 ℃ B temperature 150 ℃ C temperature 150 ℃ D temperature 90 ℃

[30] The linear resistance of the drawn fiber was measured to be about 10 ⁶ -10 ⁷ Ω/cm. The tenacity of the fiber was measured to be about 2 g/denier.

Comparative example 1

[31] This example illustrates the preparation of bicomponent fibers in which PBT is used as the carbon-carrying component and the non-conductive second component. The carbon-carrying component has a conductive carbon black loading of 25%. The fibers were spun and then drawn in substantially the same manner as described in Example 1. The tensile and electrical conductivity results are typical of several hundred products prepared using this combination of polymers (with varying amounts of carbon components, spinning speeds and stretching temperatures).

Example 2

[32] This example illustrates the preparation of bicomponent fibers in which a PET-based polyester, Americhem 19420 (with 25% carbon loading) was used as the carbon-loading component and the non-conductive second component was PTT. All other details are essentially the same as in Example 1 above.

Example 3

[33] This example illustrates the preparation of bicomponent fibers where PBT filled with 25% carbon black was used as the carbon-carrying component and the non-conductive second component was PTT. All other details are essentially the same as in Example 1 above.

[34] Table 1 below summarizes the linear resistance and tenacity of the fibers of Example 1, Comparative Example 1, Example 2, and Example 3. The ratio of drawn to spun linear resistance indicates whether there is no change in conductivity (ratio = 1.0), increased conductivity (ratio < 1.0), or decreased conductivity (ratio > 1.0).

Table 1 Example spinning denier Denier after stretching Effective stretch (spun denier/tensile denier) Spinning linear resistance (Ω/cm) Tensile linear resistance (Ω/cm) Ratio: stretching resistance/spinning resistance Spinning tenacity (g/denier) Tensile Tenacity (g/denier) 1 45 25 1.8 5×10 ⁷ 8×10 ⁶ 0.16 1.2 2.00 Comparative example 1 45 25 1.8 3.5×10 ⁶ 1.5×10 ⁷ 4.3 0.87 1.48 2 45 25 1.8 2.0×10 ⁸ 3.8×10 ⁹ 19.0 1.11 1.40 3 45 25 1.8 3.3×10 ⁶ 3.3×10 ⁷ 10.0 0.99 1.10

[35] The fiber of Example 1 exhibited about 35% higher tensile tenacity than the fiber of Comparative Example 1, wherein the fiber was produced using the same polymer processing temperature under the same processing conditions, speed, etc. Thus, the fiber of Example 1 provides improved tenacity relative to the fiber of Comparative Example 1, but because the two polymers have similar melting temperatures, the fiber of Example 1 still allows the two polymers of the bicomponent fiber Processing is carried out at the same temperature. In addition, the fibers of Example 1 have better electrical conductivity after stretching than the fibers of Comparative Example 1 or the fibers of Examples 2-3, wherein the fibers of Comparative Example 1 or the fibers of Examples 2-3 were made with Different combinations of polyesters were prepared with other conditions being the same (where the melting temperature was the same) or changed (to suit the specific melting properties of polymers with different melting temperatures).

Example 4

[36] Table 2 below summarizes the results of some other test products prepared using different grades of PBT as the non-conductive material compared with various conductive materials and two nylon-based conductive fibers. "19420" refers to Americhem 19420 (with 25% carbon loading). These results show that properly selected pairs of polymers have superior retention properties relative to other polymer combinations. The examples in this table were performed using fiber cross-sections where the conductive material is shown as strips along the longitudinal direction of the wire. "% Tape" is the weight percent of conductive polymer in the filament (wherein, in each case, about 25% of the conductive polymer is carbon black). The two columns shown as "Average Ω/cm" show the linear resistance in Ω/cm of (1) spun (or Sp) and (2) drawn (or Dr) fibers. The last column shows the ratio of linear resistance of drawn to spun fibers, where the ratio of drawn to spun linear resistance indicates whether there is no change in conductivity (ratio = 1.0), increased conductivity (ratio < 1.0), or decreased conductivity (ratio = 1.0). Ratio > 1.0).

Table 2 core Bands %Bands %core Average SpΩ/cm Average DrΩ/cm Average Dr/SpΩ PBT-APBT-APBT-A PBT-1PBT-1PBT-1 101316 908784 2.58×10 ⁶ 2.59×10 ⁶ 2.12×10 ⁶ 1.37×10 ⁷ 7.45×10 ⁶ 6.48×10 ⁶ 5.462.993.34 PBT-BPBT-BPBT-B PBT-2PBT-2PBT-2 101316 908784 3.49×10 ⁶ 2.12×10 ⁶ 4.13×10 ⁶ 1.37×10 ⁷ 4.99×10 ⁶ 6.47×10 ⁶ 4.092.352.40 PBT-APBT-A 1942019420 1316 8784 5.33×10 ⁷ 4.80×10 ⁷ 1.12×10 ⁷ 6.15×10 ⁶ 0.210.13 PBT-BPBT-BPBT-B 194201942019420 101316 908784 9.60×10 ⁷ 4.80×10 ⁷ 4.00×10 ⁷ 1.52×10 ⁷ 9.28×10 ⁶ 7.40×10 ⁶ 0.160.200.19 PBT-C PBT-1 10 90 3.76×10 ⁸ 1.78×10 ⁷ 37.33 Nylon 66 Nylon 66 Nylon 6 Nylon 6 1013 9087 9.25×10 ⁵ 1.01×10 ⁶ 1.19×10 ⁷ 1.34×10 ⁷ 13.0313.18 Nylon 66 Nylon 66 Nylon 66 Nylon 6 Nylon 6 Nylon 6 101316 908784 8.61×10 ⁵ 6.59×10 ⁵ 6.72×10 ⁵ 4.06×10 ⁶ 3.20×10 ⁶ 3.09×10 ⁶ 4.774.844.57

Example 5-16

[37] The following example presents a PBT/co-PET (Americhem 19420) polymer system in which there was variation in the relative amount of stretch between pairs of rolls on an Erdmann four-roll stretch-winder. The results are shown in Table 3. As in the other examples, the ratio of drawn to spun linear resistance indicates whether there is no change in conductivity (ratio = 1.0), increased conductivity (ratio < 1.0), or decreased conductivity (ratio > 1.0).

table 3 Example 5 6 7 8 9 10 11 12 13 14 15 16 spinning steam P l2 12 12 12 6 6 6 6 0 0 0 0 D roller speed (Mpm) 1020.0 1080.0 1140.0 1180.0 1020.0 1080.0 1140.0 1180.0 1020.0 1080.0 1140.0 1180.0 A/feed ratio 1.200 1.200 1.200 1.200 1.200 1.200 1.200 1.200 1.200 1.200 1.200 1.200 B/A ratio 1.290 1.290 1.290 1.290 1.290 1.290 1.290 1.290 1.290 1.290 1.290 1.290 C/B ratio 1.290 1.290 1.290 1.290 1.290 1.290 1.290 1.290 1.290 1.290 1.290 1.290 D/C ratio 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 Friction/D ratio 0.955 0.955 0.955 0.955 0.955 0.955 0.955 0.955 0.955 0.955 0.955 0.955 total stretch ratio 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 Feed roller speed (Mpm) 510.8 540.8 570.9 590.9 510.8 540.8 570.9 590.9 510.8 540.8 570.9 590.9 A roller speed (Mpm) 612.9 649.0 685.1 709.1 612.9 649.0 685.1 709.1 612.9 649.0 685.1 709.1 B roller speed (Mpm) 790.7 837.2 883.7 914.7 790.7 837.2 883.7 914.7 790.7 837.2 883.7 914.7 C roller speed (Mpm) 1020.0 1080.0 1140.0 1180.0 1020.0 1080.0 1140.0 1180.0 1020.0 1080.0 1140.0 1180.0 Friction roller speed (Mpm) 974.1 1031.4 1088.7 1126.9 974.1 1031.4 1088.7 1126.9 974.1 1031.4 1088.7 1126.9 Helix 6 6 6 6 6 6 6 6 6 6 6 6 Wobble 2 2 2 2 2 2 2 2 2 2 2 2 Period 6 6 6 6 6 6 6 6 6 6 6 6 A temperature (℃) 90 90 90 90 90 90 90 90 90 90 90 90 B temperature (°C) 150 150 150 150 150 150 150 150 150 150 150 150 C temperature (°C) 150 150 150 150 150 150 150 150 150 150 150 150 D temperature (℃) 90 90 90 90 90 90 90 90 90 90 90 90 Average tenacity (g/denier) 2.36 2.29 2.37 2.3 2.33 2.27 2.29 2.35 2.11 2.12 2.05 2.09 Mean Ω/cm Standard deviation of Ω/cm 7.66E+07 5.22E+07 6.67E+07 5.87E+07 5.08E+07 5.07E+07 5.54E+07 9.26E+07 1.41E+08 3.47E+07 1.01E+08 3.20E+07 5.77E+07 4.31E+07 2.11E+07 1.52E+07 3.41E+07 1.12E+07 2.09E+07 8.02E+07 1.58E+08 1.79E+07 1.02E+08 7.30E+06 Spinning Ω/7.5cm Spinning Ω/cm 6.60E+08 7.80E+08 8.00E+08 8.20E+08 7.30E+08 7.10E+08 6.80E+08 7.10E+08 3.70E+08 4.70E08 5.10E+08 4.20E+08 8.80E+07 1.04E+08 1.07E+08 1.09E+08 9.73E+07 9.47E+07 9.07E+07 9.47E+07 4.93E+07 6.27E+07 6.80E+07 5.60E+07 DR/SP resistance ratio 0.87 0.50 0.63 0.54 0.52 0.54 0.61 0.98 2.86 0.55 1.49 0.57

Examples 17-40

[38] As shown in the preceding examples, the stretching method of the final product may include multiple stretching zones. However, the properties claimed in the present invention can be obtained by using a single-step stretching machine (e.g., a stretch-winding process in which the speed difference between two rolls provides denier stretch). In this method, there is no so-called "relaxation zone" provided by the multi-roll draw-winder.

[39] Table 5 summarizes the performance results for the products prepared in the plant runs. In this example, the spun fibers were prepared using the PBT/coPET polymer system as previously described. The take up speed for both spun products was 1420 mpm. As in the other examples, the ratio of stretched to spun linear resistance indicated whether the conductivity was unchanged (ratio = 1.0), increased (ratio < 1.0), or decreased (ratio > 1.0). The test product prepared using spun product 117 had 9.5 wt% conductive carbon polymer per filament; the product prepared using spun product 122 had 14.5%. For all experiments given below, the temperature of the first draw roll was set at 100°C. The "Draw Ratio" shown is the speed ratio between the two rolls with the 2nd roll set at 1020 mpm for all products. The machine parameter settings are shown in Table 6.

table 5 Example Stretch ratio 2nd roll temperature (°C) spinning Average Ω/cm Stretching Resistance/Spinning Resistance Ratio Average Denier average breaking strength Average elongation% Average tenacity (g/denier) 171819202122232425262728 2.11.81.951.81.952.11.951.82.11.951.951.95 140140140120160160140160120140120140 117117117117117117117117117117117117 1.01E+086.67E+078.80E+071.39E+089.07E+077.47E+071.09E+086.13E+072.91E+088.80E+071.63E+087.80E+07 0.760.500.661.040.680.560.820.462.170.661.220.58 23.1327.0725.0227.2025.0523.2024.9027.0023.2025.0525.0024.90 65.6760.0761.8261.3464.0866.7061.2362.7262.3460.9862.2961.58 38.1658.8847.5760.4443.3133.8544.2357.3037.2044.8949.6142.11 2.842.222.472.262.562.882.462.322.692.442.492.47 293031323334353637383940 2.11.81.951.81.952.11.951.82.11.951.951.95 140140140120160160140160120140120140 122122122122122122122122122122122122 5.07E+073.20E+074.00E+075.87E+072.40E+072.67E+073.73E+071.87E+078.80E+075.07E+077.73E+073.93E+07 0.780.490.610.900.370.410.570.291.350.781.180.60 23.1827.1324.8727.1425.0623.1324.9627.0023.3125.1225.1424.88 55.8451.8851.9251.0955.7157.9152.6954.2553.8952.5552.3053.06 34.6756.5940.4059.2844.8132.8342.8056.2736.4143.0547.5942.53 2.411.912.091.882.222.502.112.012.312.092.082.13

Table 6 Spinning Products 117 Example Stretch ratio T2(°C) A/Feed D roll feed roller 171819202122232425262728 2.11.81.951.81.952.11.951.82.11.951.951.95 140140140120160160140160120140120140 1.051.051.051.051.051.051.051.051.051.051.051.05 102010201020102010201020102010201020102010201020 485.71566.67523.08566.67523.08485.71523.08566.67485.71523.08523.08523.08 Spinning Products 122 Example Stretch ratio T2(°C) A/Feed D roll feed roller 293031323334353637383940 2.11.81.951.81.952.11.951.82.11.951.951.95 140140140120160160140160120140120140 1.051.051.051.051.051.051.051.051.051.051.051.05 102010201020102010201020102010201020102010201020 485.71566.67523.08566.67523.08485.71523.08566.67485.71523.08523.08523.08

Examples 41-44

[40] Fibers made using this method can also be used in staple fiber applications, such as where the bicomponent fibers described herein are spun, drawn, crimped, and chopped into small discrete lengths to be shared with other staple fibers. The blend or itself can be decombed and spun into yarn. As an example, fibers of conductive carbon-filled co-polymer PET and non-conductive PBT "core" polymer were spun under the conditions described below using a single ribbon. The fibers are then made into tows by combining the ends of the spun yarn into a single large bundle, and the cellulose is drawn, crimped and chopped into staple fibers. The staple fibers were found to have sufficient electrical resistance for antistatic fiber applications. Furthermore, by selecting the appropriate combination of draw roll temperature and draw ratio, it is possible to form a final staple fiber product with a measured surface resistance lower than that of spun fibers (ie, draw resistance/spun resistance < 0). Table 7 summarizes the electrical resistance results for several staple fiber products prepared using the same spun yarn stock.

Table 7 EXAMPLES Spun Fiber Tow Denier Drawn Fiber Tow Denier DPF 4119836136712.85 4219836152283.17 4319836138422.88 4419836152013.17 Spinning fiber bundle linear resistance (Ω/cm) average 2.00E+091.05E.091.92E+091.66E+09 2.00E+091.05E+091.92E+091.66E+09 2.00E+091.05E+091.92E+091.66E+09 2.00E+091.05E+091.92E+091.66E+09 Linear resistance of stretched fiber bundle (Ω/cm) average 1.30E+142.20E+134.20E+141.91E+14 3.20E+143.80E+142.70E+143.23E+14 2.70E+082.80E+082.10E+082.53E+08 3.30E+082.00E+081.70E.082.33E+08 Surface resistance of spun fiber bundle (Ω) average 2.40E+072.80E+072.40E+072.53E+07 2.40E+072.80E+072.40E+072.53E+07 2.40E+072.80E+072.40E+072.53E+07 2.40E+072.80E+072.40E+072.53E+07 Surface resistance of stretched fiber bundle (Ω) average 3.00E+062.60E+069.00E+064.87E+06 7.00E+056.00E+059.00E+057.33E+05 1.60E+051.80E+051.60E+051.67E+05 2.00E+051.80E+051.60E+051.80E+05 Short fiber surface resistance (Ω) average 3.00E+096.00E+076.50E+071.04E+09 1.60E+071.80E+072.00E+071.80E+07 3.20E+052.80E+052.60E+052.87E+05 1.80E+052.20E+052.00E+052.00E+05 Heating of draw ratio rolls 1.6 None 1.43 none 1.6113°C 1.43113°C Resistance ratio Linear resistance of drawn fiber bundle/spun fiber bundle (Ω/cm) Surface resistance of drawn fiber bundle/spun fiber bundle (Ω) Surface resistance of short fiber/spun fiber bundle (Ω) 1.15E+051.92E-014.11E+01 1.95E+052.89E-027.11E-01 1.53E-016.58E-031.13E-02 1.41E-017.11E-037.89E-03

[41] As in the other examples, the ratio of stretched to spun resistance indicated whether the conductivity was unchanged (ratio = 1.0), increased (ratio < 1.0) or decreased (ratio > 1.0). Linear resistance was measured as previously described (in Ω/cm). Surface resistance is more suitable for measuring small fibrils, fibrils, or flat surface samples or collections (the above results are expressed in Ω). Surface resistance is measured by taking a fiber or fabric sample and conditioning it for an appropriate period of time in a controlled temperature and humidity environment. An appropriate number of samples is prepared for placement on the electrodes. The external voltage supply was set at 100 V and the resistivity of the sample at the applied voltage was measured once the reading stabilized for several seconds.

[42] The test probe used here was the EOS/EDS Standard 11.11 Surface Resistivity Probe Model 803B from Electro-Tech Systems (Glenside, PA), which consisted of two concentric soft rubber electrodes. The dimensions of the electrodes are such that the surface resistance expressed in ohms/square is 10 times the measured resistance (expressed in Ω). Readings were measured using a Model 872A Wide Range Resistance Meter from Electro-Tech or a Keithley 6517 Resistance Meter.

[43] It should be understood that, while the invention has been described in conjunction with specific embodiments, the foregoing description and examples are for purposes of illustration only and are not intended to limit the scope of the invention. Other aspects, advantages and modifications of the invention will be apparent to those skilled in the art to which the invention pertains and are intended to be within the scope of the invention which is limited only by the appended claims.

Claims (21)

1. A multi-component conductive fiber comprising: a first component comprising a first polyester having a conductive material dispersed therein, wherein the first polyester has a first melting temperature; and a second component comprising a second polyester different from the first polyester, wherein the second polyester has a second melting temperature; wherein the difference between said first melting temperature and said second melting temperature is no more than about 10°C. 2. The multicomponent conductive fiber according to claim 1, wherein said first polyester is terephthalic acid or its lower alkyl ester, C2-C10 aliphatic or alicyclic diol and one or more selected from two Modifier copolymer of alcohols, diacids and diesters. 3. The multicomponent conductive fiber of claim 3, wherein said one or more modifying agents are selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, cyclohexanedimethanol, adipic acid, horseradish Toric acid and phthalic acid. 4. The multicomponent conductive fiber of claim 1, wherein said first polyester is a polybutylene terephthalate (PBT) based polymer. 5. The multicomponent conductive fiber of claim 1, wherein said first polyester is a polytrimethylene terephthalate (PTT) based polymer. 6. The multicomponent conductive fiber of claim 1, wherein said second polyester is polybutylene terephthalate (PBT). 7. The multicomponent conductive fiber of claim 1, wherein said second polyester is polytrimethylene terephthalate (PTT). 8. The multicomponent conductive fiber of claim 1, wherein said conductive material comprises carbon black. 9. A method for preparing stretched multicomponent conductive fibers, said method comprising: The undrawn fibers are prepared by coextruding a first component comprising a first polyester with a conductive material dispersed therein and a second component comprising a A polyester different from a second polyester, wherein the first polyester has a first melting temperature and the second polyester has a second melting temperature, wherein the difference between the first melting temperature and the second melting temperature does not exceed about 10°C; and The undrawn fibers are drawn while heating to form drawn fibers. 10. The method of claim 9, wherein the electrical conductivity of the drawn fiber is not lower than the electrical conductivity of the undrawn fiber. 11. The method of claim 9, wherein said first polyester is more amorphous than said second polyester. 12. The method of claim 9, wherein the electrical conductivity of the drawn fibers is greater than the electrical conductivity of the undrawn fibers. 13. The method of claim 9, wherein said first polyester is terephthalic acid or its lower alkyl ester, C2-C10 aliphatic or cycloaliphatic diol and one or more selected from diol, diacid Copolymers of modifiers with diesters. 14. The method of claim 13, wherein said one or more modifiers are selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, cyclohexanedimethanol, adipic acid, maleic acid, and benzene Diformic acid. 15. The method of claim 9, wherein the first polyester is a polybutylene terephthalate (PBT) based polymer. 16. The method of claim 9, wherein said first polyester is a polytrimethylene terephthalate (PTT) based polymer. 17. The method of claim 9, wherein the second polyester is polybutylene terephthalate (PBT). 18. The method of claim 9, wherein the second polyester is polytrimethylene terephthalate (PTT). 19. The method of claim 9, wherein said conductive material comprises carbon black. 20. A method of making drawn bicomponent conductive fibers, said method comprising: By co-extrusion (i) conductive first component, which contains terephthalic acid or its lower alkyl ester, C2-C10 aliphatic or alicyclic diol and one or more selected from ethylene glycol, diglycol Alcohol, propylene glycol, butanediol, cyclohexanedimethanol, adipic acid, maleic acid and phthalic acid modifier copolymer; the copolymer has dispersed conductive carbon black, and (ii) non-conductive second two components, comprising polybutylene terephthalate, to produce undrawn fibers; and The undrawn fiber is drawn at a temperature of from about 80°C to about 190°C to form a drawn fiber; wherein the drawn fiber has an electrical conductivity not lower than that of the undrawn fiber. 21. The method of claim 20, wherein the electrical conductivity of the drawn fibers is greater than the electrical conductivity of the undrawn fibers.

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