JPH0663138B2 - Wool-like fluff and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is derived from a stabilized carbonaceous precursor material that imparts a morphology of a spring-like structure capable of reversible flexure of about 1.2 times the length of the fiber in the relaxed state. Wool-like fluff composed of elastic carbonaceous fibers.

The carbonaceous fibers of the present invention have a substantially permanent, non-linear, elastic, stretchable, spring-like structure morphology, eg, a sharp or sharp bend-free morphology in the fiber. The morphological and elastic stretchable features of the present invention include stretched, stretched, and substantially linear when the fiber is under tension from a relaxed (ie, spring-like) state. Allows fiber dimensional changes up to and including any degree therebetween. When under tension, the fibers are capable of stretching at least 1.2 times, typically 2 to 4 times the length of their relaxed, undeflected, spring-like fibers. Thus, the spring-like fibers can be deflected (stretched or stretched) into a substantially linear shape or configuration. The elastic modulus of the fiber itself is not reached,
Or, if this is not exceeded, i.e. the fiber is not under a tension above that required to be straightened into a substantially linear shape, the fiber will change its size or physical structure. It can return from a linear to its relaxed spring-like shape over multiple cycles of stress elongation and relaxation without breaking or substantially changing.

It is common practice in the prior art to produce filaments from pitch-based (petroleum and / or coal tar) compositions by conventional techniques by melt spinning the composition to produce continuous filaments which are then stabilized by oxidation. Is taught. Such filaments are taught to be useful by themselves. Alternatively, the continuous filaments may be cut or stretch broken into what are referred to in the art as "staple" fibers. Such "staple" fibers can be added to the yarn by drafting, drawing and / or twisting (referred to in the industry as spinning). The continuous filament can also be a tow formed from multiple continuous monofilaments. The resulting yarn or yarn is used on its own, or alternatively, woven into a textile article and used on its own. Alternatively, the woven article may be carbonized into graphite or a graphite-like cloth. Alternatively, the tow itself may be carbonized and subsequently used as a reinforcing agent for synthetic resin materials such as "prepreg" without weaving the tow into a cloth.

In a similar fashion, wet wet-spun polyacrylonitrile (PAN) into filaments, collect the filaments into tows, stabilize the filaments or tows by oxidation, and staple the filaments or tows by cutting or stretch breaking. It has been taught that the staples are spun into spun yarns, the yarns are knitted or woven into a cloth or fabric, and if desired, the resulting fabric is carbonized at temperatures above 1400 ° C. These materials are
In its pre-carbonized woven state it was used as a non-combustible reinforcing agent for metallized fire resistant clothing. In their non-woven carbonized form, these materials have also been used as stiffeners in synthetic resin materials such as golf club shafts.

In the manufacture of non-carbonized conventional polymer fiber yarns for the production of knits, fabrics or other fiber products, the fiber tows are pinched and crimped to sharply crimp set the individual fibers of the tow Or, it is a common practice in the industry to introduce sharp bends.Treatment of such textiles has the same effect when used on stabilized carbonaceous precursor yarns or tows, i.e. A crimp is applied to the yarn, which causes entanglement between the individual fibers of the yarn, helping to hold or secure the short staples, fibers in the yarn, and to impart bulk to the yarn.
When the usual textile yarn manufacturing process is used and the yarn made from the carbonaceous precursor material is crimped and then carbonized at a temperature of about 1000 ° C. or higher, and more substantially at 1400 ° C. and higher, the result is Carburized yarns become very brittle. That is, this yarn is subject to harsh handling or sharp pleating, such as knitting or weaving, unless knitting or weaving is carried out with great care and under highly controlled process conditions. I can't. For the same reason, such knitted or woven yarns cannot be easily knitted, recycled or carded without breaking the fibers in the yarn into small pieces. As a result of such brittleness, knitted knitted fabrics cannot be unraveled without special care, and such knitted yarns are subsequently carded to produce severe fiber breaks or breaks. The fibers in the yarn cannot be converted to a fluffy, wool-like material without crimping.

The prior art also generally discloses carbonized filaments with high tensile strength or high surface area. Such filaments have a highly "graphitic" nature and, as a result, use high temperatures to obtain a high degree of carbonization. However, the filaments produced by such isothermal treatment are very brittle and cannot withstand the stresses of repeated bending of the filaments. This is especially true when these filaments are exposed to temperatures above about 1000 ° C and even more so when these filaments are exposed to temperatures above about 1400 ° C. An example of high temperature processing of filaments derived from stabilized mesophase pitch is U.S. Pat. No. 4,005,183.
, Where the oxidation-stabilized fibers (at temperatures of 250-400 ° C.) have a low surface area (lower than ordinary absorbent carbon) and within the range of 1-55 million psi (7GPa-380GPa). It is made into a yarn with Young's modulus.

Fabric panel manufacturing techniques are described in U.S. Pat.No. 4,341,830, in which an acrylic filament tow
Oxidized under tension at a temperature of 200-300 ° C, the stuffer
Crimped in the box (with a pinch type crimp) and stapled. Fiberized, spun into yarn, then knitted into a woven panel and heat treated or carbonized in an inert atmosphere at a temperature of 1400 ° C. The carbonized fabric panels in this manner are accumulated in a stack and the stack is placed in a carbon steam furnace to deposit carbon on and in the stack. This treatment involves passing a carbonaceous gas, or methane, through the stack, during which the stack is electrically inductively heated to a temperature of 2000 ° C. to deposit carbon on and in the stack, the matrix of the knitted panel. To produce a carbonaceous body having However, the yarns made by this method are very fragile, as will be shown in the comparative example below, and without the severe breakage of the fibers, such as those that occur when a woven panel is unraveled and subjected to carding. It cannot be bent under acute angle stress.

Definitions "Fiber" or "filament", as interchangeable terms, refers to a fine thread or structure of a natural or synthetic material in its normal application. Included in this are fibers made by wet spinning PAN.

The term "fiber assembly" as used herein refers to a large number of filaments commonly used in the textile industry such as tows or yarns. The fiber assembly is made from conventional polymeric woven fibers or filaments, but also applies to stabilized and treated carbonaceous fibers or filaments according to the description and examples set forth below.

The terms "spring-like", "spring-like structure" or "form of spring-like structure" are used herein as interchangeable terms, from a substantially linear form to a coil form without sharp bends, Required to refer to fibers or tows that are physically deformed into a sinusoidal (sinusoidal), or other multi-curved shape or form.

The term "tow" here is defined by the number of filaments
Refers to an assembly of multiple continuous filaments identified by nK, where n is the numerical value in increments of 1000 filaments.

The term "staple" refers to a discontinuous strand of yarn or fiber that can be "spun" (drafted, drawn and / or twisted) into a yarn or yarn used in the textile and textile industry to make woven and / or knitted articles. A fiber of comparable length.

As used herein, the term "stabilize" applies to fibers or tows oxidized at a particular temperature, typically less than about 250 ° C for PAN.

The term "yarn" here is a twisted filament,
Applied to a continuous strand of yarn or fiber. The term "spun yarn" refers to a continuous strand of staple fibers drafted, drawn and / or twisted into a yarn or yarn.

The term "carding" is used herein to at least partially align staple fibers to a tangled web or sliver by combing or brushing the yarn with a toothed device such as a wire brush. Refers to the operation.

The term "recycle (garnet)" as used herein refers to a method of returning various textile wastes to fibers by passing the textile wastes through a machine called a garnet, which resembles a card.

"Knitting" here means simple jersey knit, rib knit, pearl knit, interlock knit,
Double knits and similar methods of knitting fibers, yarns or tows into fabrics are included.

"Reversible deflection" or "working flexibility" is used herein as applied to helical, sisoidal (sinusoidal) compression springs. Mechanical Derign-Theory and Practice (Mac Mil
lan Publ. Co, 1975) pp. 719-748, especially section 14-
2, pp. 721-724.

By "Hook's Law" it is meant herein that the stress applied to pull or compress an object is proportional to the strain or length change applied, as long as the elastic limit is not exceeded.

The carbonaceous precursor starting material capable of making the spring-like structured fibers of the present invention is PAN (acrylic) fiber (trade name PANOX,
GRAFIL etc.).

According to the present invention, unique articles are made from such carbonaceous precursor materials. Such carbonaceous precursor materials are formed into fibers or tows of fibers, stabilized by oxidation, and then given a spring-like structural morphology that alters the spring-like structural morphology of the fiber over many cycles of elongation and contraction. The fibers are imparted with flexibility, elasticity, stretchability and deflectability without. Fibers made from PAN are typically 200-250
It is stabilized by oxidation at a temperature of ° C and typically has a nominal diameter of 10-20 microns.

A large number of continuous fibers are collected to make a tow, which is then stabilized by conventional oxidation. The stabilized tow is then and in accordance with the invention in the form of a coiled structure, for example by winding the tow on a cylindrical rod or mandrel, or by knitting the tow into a woven or cloth form in a sinusoidal shape (sinusoidal). Corrugated) or other curvilinear (it will be appreciated that other textile and coil forming methods may also be used). It is convenient to form the sinusoidal structure on a standard knitting machine (eg a flat bed or tubular knitting machine) or in a round tooth gear box that does not impart sharp or sharp bends to the fibers. The coiled or sinusoidal fibers, tows or knitted fabrics are then heat treated at a temperature of 150-1550 ° C.

In this way, continuous filaments of acrylic fibers or their tows, which are oxidation-stabilized, are heat-treated in a non-oxidizing atmosphere under stress-free and relaxed conditions while retaining the spring-like shape to carbonize wool-like fluff. Used in manufacturing.

The fibers or tows formed into the spring-like structure form as described above are in their relaxed, unstretched, spring-like form 1.
2 times or more: 1, generally 2 times or more reversible deflection ratio. It is of course possible to allow greater elongation or extension of the spring-like fibers or tows by adjusting this structural form, for example by adjusting the number of loops per length or the number of rod or mandrel-like turns. Be understood by The tension or relaxation of a non-linear coil or curl in a fiber, such as the number of loops per centimeter in a knitted fabric of the fiber, governs the degree of elongation of the spring-like fiber or tow.

In a preferred embodiment, polyacrylonitrile is spun into fibers, the fibers are stabilized by oxidation, a large number of continuous filaments are collected into a tow, and the tow is knitted. After knitting, the fibers in the fabric are tentatively "fixed" (set) into a coiled or sinusoidal structure by first treating the fabric at 150-550 ° C. The fibers in the knitted fabric are then heat treated in an inert atmosphere in a relaxed state at the temperature at which the acrylic fibers carbonize. When the heat treatment temperature is 950 ° C. or lower, considerable nitrogen atoms are present in addition to carbon, and the log resistivity is −2.84 or more, which is particularly excellent in heat insulation and flame resistance. When heated to a temperature higher than 950 ° C and subjected to heat treatment, the log resistivity is less than -2.84, which shows high electrical conductivity like ordinary carbon fibers. Wool-like fluff from the former is particularly useful as a flameproof insulation.

The wool-like fluff is produced by cutting the carbonaceous fiber having a reversible deflection ratio of 1.2 times or more obtained as described above into a staple and subjecting it to a known mechanical treatment consisting of carding or garnet. If higher electrical conductivity in the fiber is desired, permanent set (500-1000
C.) can be further heat treated to temperatures above 1000.degree. C., for example up to 3000.degree. However, it is desirable to perform such high temperature treatment after carding or garnet treatment.

Fibers produced from carbonaceous precursor material, when produced by the process described above, usually 0.5~1600m ^{2 /} g, preferably having a surface area of 0.5~15m ^{2 /} g. However, it is known that faster heating of fibers to high temperatures can impart greater surface area to such fibers by converting non-carbonaceous moieties (which would otherwise cleave the surface if left on the fibers) into gas. Has been. Another technique known in the art for producing high surface area, high porosity fibers is oxidation of the fiber surface. Such highly porous fibers can be made from the materials of the present invention by similar techniques after imparting a spring-like structural morphology to the fibers.

Examples of products that can be produced by the techniques of the present invention are shown in the examples below.

Example 1 Oxidation-stabilized polyacrylonitrile PAN-OX (R.R.) having a nominal single fiber diameter of 12 microns (at a temperature of about 250 ° C).
K. Textiles) A continuous 3K or 6K (3000 or 6000 fibers) tow was knitted on a flat bed machine to make a fabric with 3-4 loops per centimeter. This cloth part was heat-treated at a temperature shown in Table 1 for 6 hours under an inert atmosphere of nitrogen. When I knit this cloth, it is 2
A tow with a reversible deflection ratio of more than twice (specifically 2.3 times) was produced. The braided tow was cut into various lengths of 5-25 cm and fed to a Platts Shirley Analyzer.
The tow fibers were separated by carding to give a wooly, fluffy material. That is, the resulting product is a entangled wooly mass or fluffy material, with the fibers in the material having a high clearance spacing and a high degree of overlap as a result of the coiled and spring-like morphology of the fibers. I was there. The length of each fiber of such treatment was measured and the results are shown in Table 1.

Example 2 3K or 6K PANOX (RK Texti on a singer flatbed machine
les) A woven fabric was woven from tows of continuous oxidation-stabilized filaments and heat-treated at a temperature shown in Table II under an inert atmosphere of nitrogen. The fabric was then unraveled and the tows in the form of spring-like structures were stapled and fed directly to the carding machine. The resulting wooly agglomerates were collected on a rotating drum and had sufficient integrity to allow for easy handling. The length of these fibers is 2
It was in the range of ~ 15 cm. The wooly agglomerates treated at a temperature of 950 ° C were highly conductive and had a resistance of less than 75 ohms at any test length taken at widely separated distances up to 60 cm in the wooly agglomerates. The log resistivity (logarithm of resistivity ohm-cm) is -2.84 and reversible deflection ratio is 2.3.
It was double.

Example 3 Stabilized tow of 3K PANOX is knitted on a singer flatbed knitting machine at a rate of 4 knits per cm, then under an inert atmosphere of nitrogen.
It was heat treated at a temperature of 950 ° C. This fabric was unraveled, and the tow (which had a reversible flexure ratio of more than twice) was cut to a length of 7.5 cm and then the yarn was then Platt Min.
Carding on an ature carding machine gave wooly fluff with lengths in the range 3.5-6.5 cm and average lengths of about 5 cm. This wooly fluff had high electrical conductivity over any length tested up to 60 cm.

Example 4 As in Example 3, a portion from the same knitted fabric was heat treated at a temperature of 1550 ° C under an inert atmosphere of nitrogen.
The fabric itself and the tow that was knitted from it had a very high electrical conductivity. A 15 cm length of cut tow was carded to give a fluffy material fluff with fiber lengths ranging from 2.5 to 9.5 cm and an average length of 5 cm. That is, it was found that the carding of a tow of knitted and unraveled continuous filaments exposed to temperatures above 1000 ° C. could still result in a wooly fluff.

Comparative Example A Ten double stabilized staple polyacrylonitrile PANOX yarns were knitted into tubular socks at a rate of 4 loops per cm and then heat treated at a temperature of 1550 ° C under an inert atmosphere of nitrogen. The yarn was then cut to a length of 10 cm. The cut yarn was then carded in a carding machine. The product was difficult to collect. Short fibers with a length of 0.5-1.25 cm were obtained with a large amount of debris. Fiber recovery difficulties result from the high degree of twist and fiber entanglement typically found in yarn-proof yarns. Hysol-Gr
Grafil- obtained from afil Ltd. (Combetry, UK)
Similar results were obtained when the above example was repeated using the same yarn-proof yarn of No. 01 as the raw material.

Example 5 A series of experiments were conducted to investigate the effect of different heat treatment temperatures on the fibers. A significant property was the fiber resistivity. To investigate such properties, 1.35 to 1.38 g / c
Many samples of oxidation-stabilized PAN yarn with a density of m ³
And collected in 6K tow. This tow (called PANOX,
(Manufactured by RK Textiles of Heaton-Norris, Stockport, England) into a plain jersey flat cloth with 3 and 5 knits per cm, respectively. The fabric was then heat treated at various temperatures in an oxygen-free nitrogen atmosphere in an incrementally heat-controlled quartz tube furnace. The temperature of the furnace was gradually increased from room temperature to about 550 ° C over 3 hours, and the higher temperature was increased at a rate of 50 ° C every 10 to 15 minutes. The sample was held at the desired temperature for about 1 hour and allowed to cool with the furnace open and a nitrogen purge. Typical furnace temperatures for the above heating schedule are for 6K yarns and are shown in Table III below.

Table III Time Temperature ℃ 0720 200 0810 270 0820 300 0830 320 0840 340 0850 360 0900 370 0905 380 0935 420 0950 450 1005 500 1010 550 1025 590 1035 650 1045 700 1100 750 1400 750 The specific resistance of fiber is 6 pieces. Calculated from the measurements made for each sample using the average of the values. The 6 measurements are for those made from the fibers removed at each corner of the sample and at the center of the sample from the fibers removed from each edge. The results are shown in Table IV below.

Table IV Final temperature ℃ Weight loss% Specific resistance (logarithmic value) 500 − 4.849 550 33 − 600 2.010 650 34 − 700 − − 750 37 −1.21 850 38 −2.02 900 42 −2.54 950 45 −2.84 1000 48 −3.026 1800 51-3.295 Carbonized and permanent set fibers of the present invention are such that the fibers still exhibit elasticity, flexibility, reversible flexibility, and non-weakness at temperatures sufficient to impart electrical conductivity to the fibers. It is particularly suitable for mixing with standard carpet fibers or yarns to produce a static dissipative yarn when treated at sufficiently low temperatures. Such a carpet / yarn blend has at least 0 in the carpet yarn.
It may contain 25% by weight of carbonized fibers. The weight ratio of synthetic carpet fiber to carbonized fiber is preferably greater than 100: 1 and up to 200: 1. Carpets using the carbonized fibers of the present invention exhibited a static discharge which resulted in an applied electrostatic charge of 0% in less than 1 second. The above-mentioned wool-like fluff composed of fibers having a specific resistance of −2.84 or more did not burn due to the burner flame and had an extremely high heat insulating property.

Example 6 Monsanto's 1879 nylon (trilobal) staple was blended with 0.5% by weight of the electrically conductive fiber prepared according to the present invention. This electrically conductive fiber is made by heating a tow of oxidation-stabilized polyacrylonitrile multifilament fiber knitted into a cloth, heat-treating it at about 1500 ° C, knitting it, and cutting it into staples with a length of about 18 cm. It was The blended staples were carded and the selected sliver was pin drafted three times. Recombination ratio 10:
It was 1, 3: 1 and 5: 1. The resulting draft sliver was spun into a single ply yarn with an average twist of about 4.75. Most carbonaceous fibers were broken to a length much smaller than the original 18 cm length, resulting in a large amount of carbonaceous fiber loss from what was originally included in the single spinning process. The resulting carbonaceous fiber containing a single yarn was similarly prepared but overlaid on a nylon yarn containing no carbonaceous fiber. Sues
The 3.00 / 2 lapped yarn heat set on the sen heat setting device was then tufted into 1/8 gauge, 27.03 (765g),
9.5mm pile height carpet (cut / loop type) c
A carpet with about 3 knits per m was produced. The ratio of carbonaceous fiber / non-carbonaceous yarn during the tufting operation was 1: 5, respectively. A portion of this carpet was lined with a commercially available non-conductive latex carpet backing material. The resulting carpet was tested for its electrostatic discharge properties by charging it to 5000 volts in an atmosphere of less than 20% relative humidity. Static charge is less than 1 second, less than 1 second
%, And some samples discharged in less than 1/2 second. The industrial standard is a release of up to 0% within 2 seconds.

This example shows that temperatures above about 1000 ° C. can be used to heat set the spring-like structural morphology to the carbonaceous fiber tow, but at temperatures above 1000 ° C. many weakenings occur,
The resulting fibers are used inefficiently, are lost as short fibers and are not incorporated into the yarn when drafted with ordinary carpet staples to make singles.

Reference Example 1 In another experiment, a flat stock cloth was knitted to make a tow. The tow was a stabilized polyacrylonitrile precursor with the indicated number of filaments heat set at the indicated temperature prior to knitting. The elastic deflection was measured by applying a known load to the tow section, and the intermediate and final deformation as well as the final inelastic elongation deflection was measured.
These decisions are shown in Table V.

Comparative Example B To demonstrate the effect of tension on the fibers in the spring-like morphology of the set, a 6K tow of Panox continuous fiber was rolled into an 8 mm push rod. Example 5 of this rolled tow
Heat treatment was carried out at a final temperature of 300 ° C. according to the schedule shown in Table III, while firmly holding the ends of the wrapped tow. This heat treatment fixed a spring-like morphology to the tow. However, the fibers were so stiff that it was difficult to remove the tow from the bar. Many of the fibers broke during removal. This tow did not have the same elasticity as the heat-set tow in a relaxed braided form. Using the same method except heating the spring-like tow to a temperature of 350 ° C. resulted in even more breaks even before removal.

The latter method was repeated and the heat treated material (350 ° C) was carefully removed from the bar and then slowly heated to a temperature of about 650 ° C in the relaxed state to see if annealing occurred. No annealing occurred. The generator coil was brittle and not elastic.

However, removing the coiled tow from the rod before reaching 275 ° C and inserting a rod with a smaller diameter to maintain the integrity of the spring-shaped body and heating it in this "relaxed" state,
A spring-like tow having substantially the same properties as the above-mentioned braided tow was obtained.

Comparative Example C An experiment was conducted on the technique disclosed in U.S. Pat. No. 4,193,252 (corresponding to JP-A-54-40885). First, an experiment was conducted on rayon, which is the only precursor specifically described therein.

(a) 3 using a single-ended jersey style circular knitting machine
Knit a sock with a diameter of about 2 inches (about 2.5 cm) using a rayon continuous tow yarn of 00 denier and 1650 denier, cut each knitted sock into four parts,
Put three pieces of 300 denier socks from Yan Toe into the tube furnace, one at a time, closing the furnace in each case 15
Nitrogen was bubbled through for a minute and gradually heated. The first part is heated to 370 ° C in 1 hour 30 minutes, the second part is heated to 550 ° C in 1 hour 45 minutes, and the third part is heated to 1050 ° C in 1 hour 15 minutes. did.

The first part, heated to 370 ° C, is flexible and substantially electrically non-conductive, and this tow can be hand-knitted; it has a sinusoidal shape and is straight with almost no breakage of individual fibers. Stretched. However, when this tow is heated by wiping hot air with a heating gun (hair dryer), the sine waveform disappears, and the "fixed" (sine waveform or coil shape of the tow) is tentative, and the minimum weight reduction as a result of this heat treatment process. It turned out that it was seen (that is, not carbonized).

The second part, heated to 550 ° C, is of medium flexibility.
It has an electrical resistance of × 10 ⁹ ohm / cm ² and is substantially electrically conductive. This tow can be carefully disassembled by hand, but 2.5 to 5
Breaking into small pieces with a length of cm, the broken part of the disentangled tow has a sinusoidal morphology, but each can not be reversibly stretched without breaking, that is, the constituent fibers of the disentangled tow are as much as possible. It was unavoidable to break into small pieces no matter how carefully the sine wave form of the tow was stretched into a straight line. However, the yarn was broken by the hot air from the heating gun, and the yarn strands consisting of short fiber bundles were fragile and could not be separated into individual fibers with a length of about 1 cm or more even with the utmost care. I knew it was possible. That is, there was no reversible flexibility.

The third part, heated to 1050 ° C, is much less flexible than the previous one, and this third part is less than 75% of its original dry weight.
%, Resulting in a significantly smaller fiber diameter, the third portion having an electrical resistance of 70 ohm / cm ² and being substantially electrically conductive, careful after heat treatment It was not possible to pull out the tow from the knitted fabric even by hand, the fibers were broken into small pieces each time the tow was tried to be pulled, and 1.25 cm when the unwoven fabric of the third part was tried.
Fiber tows of less than length were obtained, which were found to be non-stretchable because they had a sinusoidal morphology but the individual fibers in the tow were even smaller fractured. That is, there was no reversible flexibility.

(b) Next, 1200 denier spun yarn of oxidatively stabilized acrylic fiber was knitted using a single-ended jersey style circular knitting machine to make a 2 inch sock.

Cut this sock into four parts, one at a time
They were placed in individual tubular furnaces, the furnace was closed in each case and gradually heated for 15 minutes by passing nitrogen through. 50 minutes for the first part over 15 minutes
Heated to 0 ° C, the second part heated to 600 ° C over 15 minutes, and the third part heated to 950 ° C over 15 minutes.

Each part could be disassembled and had a sine wave form. However, each fiber was tested and found to be extremely brittle and its brittleness was due to the tensions that were inevitably applied to the fiber when it was spun yarn and during subsequent heat treatment. There was no reversible deflection.

The logarithmic value of the specific resistance of the fiber from the first part is +5,
The logarithmic resistivity of the fibers from the second part was +2.2 and the logarithmic resistivity of the fibers from the third part was -2.7.

When this fiber was passed through a carding machine, it was extremely fragile and was broken into small pieces to give a dust-like substance. There was no reversible flexibility.

The socks before heat treatment were unknitted and the resulting spun yarns were tested and found to be under tension caused by the twist imparted during the twisting process to hold the fibers together.

When knitting this yarn, it was found that the fibers contained in the spun yarn, not the yarn itself, are under tension and this tension increases due to the mass loss (loss) and shrinkage of the fibers in the carbonization process.

The bulky yarn structure had some tensile strength, but the individual fibers were brittle and could not be made into wool-like fluff or battein.

That is, in the conventional method, it is not possible to repeatedly draw (elongate) a non-linear carbonaceous fiber having multiple curves into a linear state without breaking the fiber. In other words, the reversible deflection ratio according to the present invention cannot be measured.

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Claims (3)

[Claims] 1. A cut staple of carbonaceous fiber having a reversible deflection ratio of 1.2 times or more obtained by heat-treating a substantially filament of oxidation-stabilized acrylic fiber in a non-linear spring form. Wool-like fluff, which consists of entangled aggregates. 2. A resistance of less than 75 ohms when measured across a wooly fluff at a probe distance of about 60 cm.
Wool-like fluff as described. 3. A tow consisting of continuous filaments of substantially no oxidation-stabilized acrylic fibers is imparted with a non-linear spring-like feature and the stabilized acrylic fiber tow with this non-linear feature is stressed. After heat-treating under non-oxidizing conditions under a non-relaxing condition to carbonize the fiber to give substantially permanent heat setting and a reversible deflection ratio of 1.2 times or more, the fiber is cut into staples, A method for producing a fluffy wool, which comprises forming a fluffy wool-like material composed of a fiber aggregate obtained by subjecting the staple-like fibers to a mechanical treatment such as a carding treatment or a garnet treatment.