JPH02242920A - Carbon fiber containing composite metal - Google Patents

Abstract

PURPOSE: To obtain a composite metal-loaded carbon fiber having high thermal oxidation resistance and high strength, and having great utility in space apparatuses, aircrafts and the like by impregnating a fiber with a combination of boron and a specific heavy metal. CONSTITUTION: This carbon fiber is obtained from a fiber material prepared, for example, by impregnating (A) a polymer filament obtained by spinning a polymer filament spinning solution containing 10-30 wt.% of a polymer material (e.g. acrylonitrile homopolymer) with (B) 70-98.9 wt.% of carbon, 0.1-15 wt.% of boron and 0.5-15 wt.% of a heavy metal (e.g. tantalum, niobium, hafnium or zirconium) selected from a group consisting of elements in groups IVB, VB and VIB of the periodic table.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to %1 carbon fibers and methods for their production. More specifically, the present invention relates to metal-filled carbon fibers and methods of manufacturing them.

Carbon fibers make them high strength and chemical resistant.

Due to its heat resistance and low weight, it is attracting attention as a reinforcing material for various composite materials. For these preferred percentages, carbon fiber is used for aircraft and spacecraft.

It has been successfully used as a material in sports equipment and many industrial applications. Although these fibers generally have good physical properties, they often suffer from poor oxidation resistance at high temperatures; for example, they are completely destroyed after about 6 hours on contact with air at 500°C. Be turned into ashes.

To improve such oxidation customization, fiber protection systems have been produced by using a combination of three one-shot approaches, two surface coatings, an oxygen diffusion barrier layer, and matrix modification.

Ceramic surface coatings are widely used to demonstrate that the anisotropic thermal expansion of high strength/high modulus fibers upon thermal cycling maintains the integrity of the protective barrier (with different coefficients of thermal expansion) around reinforcing carbon fibers. make it difficult.

The barrier layer and matrix modifier are crack-resistant.
It is only valid until ing) occurs. In particular, Matrix Brief (ma jr iX brief)
), exposed carbon fibers have the same defects as unmodified carbon fibers, unless oxidation-resistant carbon fibers with structural bond ratios at elevated temperatures are produced. Such fibers are produced with oxidation-resistant additives and/or surface coatings. For example, U.S. Pat. No. 4,162,301 impregnates preformed organic polymer fibers with a solution of specific metal compounds, stabilizes the fibers with a heating and drawing system, and then heats the fibers to elevated temperatures in a non-oxidizing atmosphere. Discloses a method for producing metal-filled carbon fibers produced by carbonizing these fibers.

The metal salt is dissolved in a bath and introduced into the metallic preformed organic polymer fiber by dipping the fiber into the bath. As metals, the periodic table [group VB, group VB, group %'l
Metals from Group B are disclosed as well as boron, aluminum, silicon, thorium, uranium, protonium. Although U.S. Pat. No. 4,162,301 discloses the impregnation of fiber precursors with certain metals, the combination of boron and certain metals to produce highly improved metal-loaded carbon fibers load on carbon fiber, polyacrylonitrile lil fiber precursor (prelousOr f'1
ber) The method of impregnating the metal with metal, ie, the specific method of the present invention, is not disclosed.

U.S. Pat. No. 4,197,279 discloses an acrylic carbon fiber containing a phosphorus component and/or a % diboron component, and further includes a zinc component and/or a calcium component.

Although this patent discloses impregnation of acrylic fiber precursors, including polyacrylonitrile fibers, it does not disclose impregnation of fiber precursors with a combination of boron and certain heavy metals as disclosed in the present invention. There is.

U.S. Patent No. 3,803,056 is titanium, tantalum.

A method for producing carbon fibers containing niobium, zircon or other such heavy metals is disclosed. However, this patent discloses the polyacrylonitrile fiber precursor used in the present invention and requires the incorporation of about 0.05 to about 6% nitrogen into the fiber precursor.

Furthermore, the method of this patent requires mixing of the fibers in a hot metal salt solution and does not suggest combined impregnation of the fibers with heavy metals and boron. Therefore, the methods of this patent and the present invention are different.

It is therefore an object of the present invention to produce improved composite metal filled carbon fibers.

It is another object of the present invention to produce metal-filled carbon fibers containing boron and heavy metals.

Fibers are impregnated with a combination of boron and certain metals,
It is yet another object of the present invention to disclose high temperature oxidation resistant, low decomposition metal filled carbon fibers.

Other objectives mentioned above 1. Scope of the present invention? 11. The quality, uses of the product, and methods for its manufacture will be apparent to those skilled in the art from consideration of the following detailed description and claims.

According to the invention, from about 98.9 to about 70% by weight carbon.

From about 0.1 to about 15% by weight boron, Group 11VB of the Periodic Table.

The fibrous material comprises from about 1% to about 18% of a heavy metal selected from the group consisting of Group VB, Group VIB elements.

Producing improved composite metal filled carbon fibers.

It consists of the following steps. A method for producing these improved composite metal-loaded carbon fibers is also provided: a. producing a polymer filament spinning solution; b. spinning the polymer filament solution into filaments; c. a boron compound and the one period law. A step of introducing into the filament a combination with a salt of at least one heavy metal selected from the group consisting of elements included in Group IVB, Group VB, and Group VIB of the table; d. A combination of the boron compound introduced into the filament and insolubilizing the heavy metal salt combination to form a fiber precursor; r. stabilizing the fiber precursor; and g. carbonizing the fiber precursor to form a boron/heavy metal combination loaded carbon fiber.

These composite metal-filled carbon fibers have great utility due to their high strength and oxidation resistance at high temperatures in applications as aircraft materials and other industrial applications where high oxidation resistance is cracking.

The carbon filament precursor of the present invention is derived from the present habolymer fiber material. Although the polymeric fiber material is made from engineered regenerated cellulosic material (eg, rayon), in preferred embodiments the fiber-forming polymer is either an acrylonitrile homopolymer or an acrylonitrile copolymer. Acrylonitrile homopolymers are particularly preferred. Suitable copolymers generally contain a small amount (approximately 93 mole percent acrylonitrile) of IJ repeating units co-incorporated therewith with one or more monovinyl units. Representative monovinyl units that can be incorporated into acrylonitrile copolymers include styrene, methyl acrylate, methyl methacrylate, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl pyridine, and the like. Acrylic polymers can be made by standard polymerization methods well known in the art.

Optionally, a small amount of pre-oxidation, graphitization catalyst can be introduced into the bulk acrylic polymer prior to spinning.

The solvent used to form the polyacrylonitrile spinning solution is a conventional spinning solvent, and in a preferred embodiment the solvent is dimethylacetamide. Standard industrial or commercial grade dimethylformamide can be used as a solvent in forming the spinning solution.

Sufficient acrylic polymer is added to the dimethylacetamide solvent to obtain a solution suitable for extrusion, containing about 10 to 30 weight percent, preferably about 15 to 25 weight percent, of acrylic polymer based on the total weight of the spinning solution. By dissolving, a spinning solution can be produced. In a particularly preferred embodiment of the invention, the spinning solution contains acrylic polymer at a concentration of about 16-20% by weight, based on the total weight of the solution. The low shear viscosity of the spinning solution is in the range of about 90 to 3,000 poise measured at 25°C. Spinning interruption generally occurs if the spinning solution has a low shear viscosity of much less than about 80 poise as measured at 25°C. Particularly high spinning pressures are required if the low shear viscosity of the spinning solution is much higher than about 3,000 poise, measured at 25° C., resulting in blockage of the extrusion orifice.

The spinning solution additionally uses lithium chloride as an additive. The mixing of lithium chloride serves the function of lowering the viscosity of the spinning solution and preserving it when left standing. Therefore, the fluidity and mobility of the target solution is well maintained over time. from about 0.5 to about 2 based on the total weight of the solution
Incorporation of lithium chloride at the weight percent level reduces the viscosity of the dope by about 50%, allowing for the production of improved stability dopes. However, this improvement in viscosity was short-lived, around 18
Doped applications of ~24% require higher proportions of lithium chloride, up to about 12% by weight.

However, these higher percentages of dope require excessive pressure in the spinneret, reducing the spinning speed below that normally achieved with lower percentages of dope. Approximately 16-18
% of the acrylic polymer yields a satisfactory spinning solution without the addition of lithium chloride additives. Thus, preferred embodiments do not include lithium chloride as an additive in the acrylic polymer concentration from about 16% to about 18%. If lithium chloride is added to the solution, it is dissolved in the dimethyl-acetamide solvent at the same time as the acrylic polymer, or before or after dissolving the acrylic polymer. A small amount of preoxidation or graphitization catalyst can optionally be added to the spinning solution.

The spinning solution is prepared in a plate or frame press containing a suitable material prior to wet spinning to ensure the removal of extraneous solid material that could block the extrusion orifice during the spinning operation. It is preferable to pass p by connecting to the same.

A spinning solution containing a dissolved fiber-forming acrylic polymer is extruded into a coagulation bath under conditions such that acrylic filaments having an internal structure can be formed, and the resulting acrylic filaments are then heat treated to form the improved carbon of the present invention. A filament is obtained.

It also consists essentially of about 45-85% by weight non-solvent for acrylic filaments and about 15-55% by weight solvent for acrylic filaments. Temperature about 0°C to 45°C [preferably about 10°C
It has been found that acrylic filaments are produced when using a coagulation bath of ~65°C]. The nonsolvents used in the coagulation bath are those conventionally used in coagulation baths for acrylic filaments, such as ethylene glycol, methanol, inpropatol, water, etc., with methanol and ethylene glycol being the preferred nonsolvents.

The preferred solvent used in the coagulation bath is dimethylacetamide. When dimethylacetamide is used at concentrations greater than about 55% needles, filament breakage in the spinneret tends to occur. When dimethylacetamide is used in the coagulation bath at concentrations less than about 15% by weight, the resulting filaments lose their substantially circular cross-section.

They tend to exhibit a more clearly bean-like morphology.

Thus, in a preferred embodiment, the coagulation bath consists essentially of about 30 to 75 weight percent ethylene glycol or methanol and about 25 to about 40 weight percent dimethylacetamide.

The temperature of the spinning solution during extrusion should be within the range of about 0°C to about 90°C, preferably about 20°C to 30°C. In a particularly preferred embodiment of the invention, the spinning solution is at room temperature ( For example, at about 25° C.), rapid handling and storage of the spinning solution is facilitated.

The spinneret used during extrusion has a single hole.

A monofilament is extruded through this. or preferably a plurality of holes through which the plurality of filaments are extruded as a yarn or tow. For example, 2
A tow of up to 0,000 or more continuous filaments may be formed. The spinneret has a spin denier of about 5-24 denier/filament. pores of about 50 to 150 micron diameter when producing relatively low denier filaments, and having pores of about 50 to 150 micron diameter when producing relatively high denier filaments having a spin denier of about 100 to 1,500 denier/filament. Preferably, the pores have a diameter of about 300-500 microns. Approximately 100-700p
It is convenient to choose an extrusion pressure of Si, preferably 100 to 4 psi. Spinning or extrusion speeds of about 0.5 to about 25 m/min, preferably about 75 to about 15 m/min can be used.

Preferably, the coagulation bath is circulated throughout the extrusion process. Continuous withdrawal and purification maintains a relatively constant composition within the coagulation bath. Instead of this,
Supplemental non-solvent can also be constantly added to the coagulation bath to maintain the desired solvent/non-solvent ratio within the coagulation bath. The residence time of the fibers in the coagulation bath is at least about 6 seconds. For example, residence times of about 6 to 300 seconds are advantageously selected.

Residence times of less than about 6 seconds result in insufficient development of the fiber structure within the spun filaments.

The obtained spun filaments are placed in a spinning bath (Spinboth).
) Immediately after taking it out from the swelling bath (imbibi-ti
on bath). In order for the boron and metal salt to be absorbed to a large extent by the fiber precursor, the fiber must be swollen as much as possible.

For example, the fiber precursor can be preswollen in water or other such materials before being immersed in the yield swelling bath. Preferred preswelling agents are aromatic alcohols.

Swelling or impregnation of the fiber precursor can be carried out in several ways. For example, if the metal salt is highly soluble in water, the swelling step can be carried out simply by dipping the swollen organic fiber into a concentrated aqueous solution of such metal salt. In another example, the preswollen fiber precursor is added to about 15% of the preswollen fiber precursor to impregnate the blend with the boron compound.
% or less of weak boric acid can be sprayed.

The main advantage of the impregnation method is the uniform distribution of fine particles within the resulting fiber. To increase the degree of impregnation, the temperature of the bath can be increased as long as it does not adversely affect the non-solvent used in the heating bath. For example, when using ethylene glycol as a non-solvent, the bath temperature should be approximately 0°C to approximately 150°C.
, preferably within the range of about 0°C to about 100°C. However, such an increase in temperature is not appropriate when using methanol as a non-solvent. Although some elevated temperatures are useful to enhance particle dispersion, excessive heating proves not useful.

To increase the degree of impregnation, the temperature of the bath, depending on the nature of the non-solvent, is usually about 0°C to about 150°C, preferably about 0°C.
℃ to about 100℃.

The immersion time in the swelling bath included the desired percentage of metal salt within the fiber, the temperature of the bath, and the rate at which the particular metal salt was absorbed into the fiber precursor. It depends on several factors. In preferred embodiments, the soak time at the preferred temperature is about 0.5 to about 10 seconds. If the preferred metal salt is not readily soluble in water, other organic substances such as bromoform, carbon tetrachloride, diethyl ether, nitrobenzene, methanol and other organic substances that do not react interferingly with the fiber precursor may be used. Any suitable solvent can be used.

The metal salt used for impregnation is a carbide-forming electric metal salt containing carbides that are stable at high temperatures. Heavy metals include the group consisting of the elements of Groups 1VB, VB and %IIIB of the periodic table; heavy metals include titanium, tantalum, niobium, chromium, molybdenum, and vanadium.

Preferably it is selected from the group consisting of zircon and thorium, most preferably tantalum, titanium, niobium, zircon and hafnium.

Soluble salts of the present metals useful for the present invention include salts with strong and weak acids, preferably with highly soluble acids. Salts of heavy metals that are OT-soluble can be used in the swelling liquid.

Typical metal salts used are chlorides and fluorides.

Contains acetate, silicate and other metal salts that are readily soluble in the selected swelling bath. For example, if niobium is the heavy metal of choice, niobium pentachloride is the preferred niobium salt.

The addition of metal salts I to the fibers naturally depends on the desired concentration of metal in the final product. Once the metal in the fiber is carried out the carbonization process increases. Accordingly, about 0.5 to about 20
To produce carbon fibers having a gold Ma of 1%, the metal concentration in the fibers before carbonization should be within the range of about 0.5% to about 10%.

Although the concentration of metal salts within the fiber after swelling can vary.

In a preferred embodiment, the proportion of metal salt incorporated into the fiber precursor is from about 0.5 to about 0.5, based on the total weight of the fiber precursor.
It should be about 15%.

The addition of boron to the fiber precursor is somewhat complex and requires incubation of the fiber precursor into two or more baths, usually containing a boron compound. A preferred method of adding boron to the fiber precursor is by adding it to a coagulation bath, such as a boric acid solution having a concentration of about 1 to about 15%, or into a metal salt swelling bath. Furthermore, to increase the concentration of boron within and on the fiber precursor
Boric acid can be combined with other liquids during subsequent stretching or drying operations. After each treatment with boric acid.

Preferably, the fibers are lightly rinsed with water to remove excess boric acid from the fiber surface. By additional treatment of these with boric acid.

The proportion of boron in the fiber precursor increases by 1%, and the fiber precursor before carbonization is about 0.1% ~ 0.1% based on the total weight of the fiber precursor.
It will have a boron loading of about 5%.

After the swelling step, the swollen ρ metal must be insolubilized so that it is not washed out of the fiber during subsequent processing. Various methods can be used to insolubilize metal-containing fibers. For example, wire fibers can be made insolubilized by treating the fibers with chemicals to fix the metal within the fibers. For example, when tantalum pentachloride is used as the salt, tantalum pentachloride is converted into tantalum oxide and made insoluble by treating the fiber containing tantalum pentachloride with aqueous ammonia. Collect the ammonia water in a tray, and remove the fibers from the skewed oars of this tray.
Weed roll) Thread the yarn (ya
rn) was effectively subjected to alkaline immersion treatment. This soaking tray is constantly removed.

Recirculate the ammonia to keep it fresh.

Many other methods can be used to insolubilize the fibers, as long as the metals are sufficiently insolubilized so that subsequent processing does not wash them out of the fibers. The concentration of ammonia in the insolubilization bath is within the range of about 10% to about 40%.

After insolubilization, the fibers can be washed in a water bath to remove excess ammonia. A variety of methods may be used to remove excess solution, including thorough blotting with a cloth, vacuum filtration, and wash baths.

In a preferred embodiment, the filament is then washed with water to remove not only excess solution, but also any residual amounts of solvent, coagulation bath, and inorganic compounds (eg, lithium chloride).

The water washing process is conveniently performed in an in-line operation after the filament leaves the swelling and insolubilization bath.

A conventional filament cleaning roll can be used. Alternatively, the filament is washed with water at 0C while being wound on a porous pobbin or using other washing means as will be apparent to those skilled in the art.

The spun and washed acrylic filament is drawn or stretched from about 1.5 times its initial length to the filament's break point to orient the filament and thereby provide its tensile strength.

A total draw ratio of about 1.5:1 to 15:1 is generally selected. Stretching is generally at elevated temperatures, preferably about 2:
It is carried out at a total draw ratio of 1 to 12:1. The compact internal filament structure allows the use of relatively high total draw ratios as described above. As will be apparent to those skilled in the art, drawing of spun and washed acrylic filaments can be accomplished by a variety of methods. (e.g., a filament) (a) immersed in a heated liquid drawing medium; (b) a heated gas atmosphere (e.g., at a temperature of about 1200 to about 200°C);
Stretching can be carried out while suspended in the hair or while in contact with a heated solid surface (e.g., at a temperature of about 130 DEG to 170 DEG C.). If desired, the total stretching imparted to the filaments can be carried out by combination of the above methods. When using drawing methods 1bl and IcI, it is important that the acrylic filaments are fed to the drawing zone in essentially dry form. If drawing method 1al is used, the acrylic filament is then washed to remove the drawing medium.

dry. Additionally, several drawing media can also perform a cleaning and/or coagulation function, so that residual amounts of dimethylacetamide are removed from the washed fibers.

In a preferred embodiment of the invention, the fc cleaned acrylic filament is at least partially drawn while immersed in a hot liquid bath, and in a preferred embodiment maintained at a temperature of about 0°C to about 100°C. In a hot water bath, about 1=
Filamentary drawing at draw ratios from 1 to about 6=1. In addition to boronic fibers, the bath water can include boric acid in the range of about 5 to about 20%.

After the hot water/boric acid bath, the filament is heated at about 10° to about 50°.
It can be cleaned by water washing at relatively low temperatures of C.

In other preferred embodiments of the invention, the filament is immersed in a hot glycerin bath at a temperature of about 0°C to about 110°C and drawn at a draw ratio of about 1.5:1 or even up to about 3:1. , cold water (e.g.

Wash at a temperature of about 10° to about 50°C] and wash at a temperature of about 110°C.
Temperatures from about 150° to about 13°C, preferably from about 150° to about 13°C
It is stretched at a draw ratio of about 6=1 to about 6:1 from contact with a hot shoe (5 hoe) at a temperature of 0°C.

The drawn acrylic filaments may optionally be formed into high denier yarns or tows, as will be apparent to those skilled in the art, prior to thermal conversion of the drawn acrylic filaments to the improved carbon filaments of the present invention as described below. can.

Stabilizes the metal/boron-containing fiber precursor in preparation for the carbonization process. To stabilize the fibers, the metal compound-absorbing organic fibers are heated under controlled conditions to a temperature of about 10°C to about 280°C to make the fibers nonflammable. It is necessary to heat at a sufficiently low rate that it can be avoided.

The first heating step is carried out in a non-oxidizing, inert atmosphere such as that created by nitrogen, helium, argon, neon, etc., or in a vacuum. but.

If it is desired to reduce the amount of residual carbon from the polymer pyrolysis step, some or all of the first heating step is performed in an oxygen-containing atmosphere. In the stabilization or preoxidation process, the fiber undergoes a series of reactions that oxidize and crosslink molecules. The net reaction is exothermic and the ossification reaction tends to form a skin/core structure in the fiber cross section. Stabilization is performed in a multi-step process to control heat generation and skin/core formation. The temperature gradually increases as the fiber passes through the various steps. Maintaining controlled tension to prevent misorientation of molecular chains and the corresponding drop in tensile strength.

The fiber precursor is fed to the dryer through a tensioning device and a feed roll stand. This material is heated to a temperature of about 10° to about 210°C to eliminate residual solvent, moisture, and ? l# agent (1ubr
icant) kremovalYle. ;CO) During drying, fibers typically shrink by about 1 to about 10%? experience. The yarn is then passed through a series of dryers that gradually increase the temperature from about 250<0>C to about 280<0>C. Once the yarn is stabilized,
An additional 10 to about 15% shrinkage is experienced. As mentioned above, adjust the contraction ff.

Roll speed to maintain acceptable tension levels?
Set. As the oxidation and crosslinking reactions progress, the yarn changes color until it appears black. After heating at an elevated temperature for from about 1 hour to about 5 hours, the yarn was fully oxidized and crosslinking proceeded with the carbonization process.

The carbonization temperature at which the stabilized yarn is processed through a nitrogen purged induction furnace ranges from about 1250°C to about 2500°C, depending on the particular metal additives and end product. During carbonization, elements such as hydrogen, oxygen, and nitrogen are gradually released from the fiber structure. The result is variable percentage weight loss from the fiber precursor, but the loaded metal is generally fully retained. As the mass loss of the fiber increases, the weight proportion of metal increases. However, under certain circumstances, the percent concentration of boron does not increase because a loss of boron occurs during the stabilization or carbonization process. It can be used for periods of about 1 to about 4 hours, but can also be used for very short periods of time.

The fibers produced by this method are about 99% to about 70% carbon.
%, a heavy metal selected from the elements of Groups IVB, VB, and VIB of the Periodic Table, and about 1% to about 30% boron. Periodic table 1V B group, VB
When using a composite load using both boron and a heavy metal selected from Group VIB elements, *alloy metal carbon fiber with about 98.5% to about 70% carbon and about 0° boron. It consists of a fibrous material containing from 5% to about 15% and from about 1% to about 15% heavy metals.

Composite metal-filled fibers showed an unexpectedly significant improvement over unloaded or single metal-filled fibers.

In particular, these fibers have significantly lower oxidation rates and greater retention of tensile strength after being exposed to an oxidizing atmosphere than unloaded fibers or single metal filled fibers.

These high strength, high modulus carbon fibers impregnated with boron and tortoise metal are very useful in situations where high temperature stability ratios are important, such as in aircraft or space equipment. In particular, resistance to decomposition at high temperatures, along with high tensile strength, are valuable properties that are very useful for single-use equipment materials exposed to high temperatures and high stresses. Additionally, the fibers can be used to make products that maintain structural integrity without the use of protective coatings.

The following examples are given as a detailed description of the invention. All parts and percentages are by weight unless otherwise stated. However, it will be understood that the invention is not limited to the specific details set forth in the examples.

Example 1 A 16% by weight polyacrylonitrile homopolymer dissolved in dimethylacetamide solution is passed through a 100 micron spinning rod with 2 to 300 holes. The mixture was extruded into a spinning bath consisting of 30% dimethylacetamide and 70% methanol at a speed of 1/min.

Swollen fiber precursor ff: TaCz32 heavy key%, 838
The fiber precursor was incorporated with tantalum and boron by passing it through a soaking solution containing 0.37% dimethylacetamide, 18% dimethylacetamide, and 76% methanol. The soaking bath was maintained at a temperature of approximately 25°C. After passing through a soaking bath.

The filaments were washed with a 28% aqueous ammonia solution and an additional water rinse at a speed of 10 m/min. Next, the fiber was stretched in hot water containing 10% H3B03 solution (8
7° C.) with a draw ratio of 2.8:1. The fibers were then washed again in a water washing bath at a line speed of 28 m/min, 2nd then dried on heated rolls at 108°C, 7th the fibers were then washed in a steam tube maintained at a temperature of 124°C for 2.5: It was stretched at a stretching ratio of 1. The fibers were then heated again to a temperature of 108° C. on a heated roll at a roll speed of 70 m/min. Analysis of the I fiber showed a loading of 1% by weight tantalum and 2.6% boron.

It was then stabilized at °C by passing it through a fibrous drying zone. The feeding speed is 101 nch/min.

The fibers were incubated at 195°C for 98 minutes at 220°C.
C22, 1 minute, 86 minutes at 250°C.

91.2 minutes at 230°C and 9 at 275°C
6. Dry for 1 minute. The total fiber shrinkage after this drying process was 16.5%.

The fibers were then carbonized in an induction furnace at a temperature of about 205.0° C. for about 2 minutes. The feeding rate of fiber to the furnace is 21.251
nch/min. The atmosphere of the furnace was flushed with nitrogen during the carbonization process.

Carbon fiber containing 1.5% tantalum and 6.9% boron is 2
It exhibited a tensile strength of 7 Q KSi and a modulus of 68.2 MSi (ASTMD3379 and Di 577).

After oxidation for 24 hours at a temperature of 500 °C (ASTMD4
102), tensile strength is 236 KSi, initial elastic modulus S13
It was 5.9 Msi. Thermogravimetric analysis of carbon fiber at 20°/min heating rate in air is 5% at 850°C.
It showed weight loss and 70% weight loss at 1000°C.

Example 2 As a comparison, an unloaded polyacrylonitrile fiber precursor was prepared and processed into carbon fiber. Polyacrylonitrile homopolymer solution in dimethylacetamide was passed through two 300-hole 100-micron diameter spinnerets at a rate of 7.91 min.
%, and extruded into a spinning bath containing about 70% methanol. The swollen fibers were then washed on two washing rolls in a water bath at a speed of 10 m/min. The fibers were then drawn at a draw ratio of 2.8:1 in a hot water bath maintained at a temperature of 92° C. and washed twice by water washing.

It was dried on heated rolls at 108°C with a roll speed of 28 m/min. The horse mackerel fibers were then drawn at a draw ratio of 2.5:1 in a steam tube heated to a temperature of 124°C and passed over heated rolls maintained at a temperature of 2108°C at a speed of 70.2 m/min.

These fibers were then heated in a furnace at 195°C for 98 minutes, 235°C for 22.1 minutes, and 250°C for 8 minutes.
62 minutes at 230°C 93.2 minutes at 275°C
The quintic fibers were stabilized by heating for 9,546 min at 100 ml under a nitrogen atmosphere.

Carbonization was carried out at a temperature of 2.050°C with a feed rate of 21.251 nch/min. Non-loaded carbon fiber is 790
It shows a 5% volume loss at ℃ and only 1 at 900℃.
．． It showed only 6% residual amount.

Implementation vAJ 3 A 16% polyacrylonitrile homopolymer dissolved in a dimethylacetamide solution was prepared using two 300-hole, 100
through a micron diameter spinneret.

It was extruded at a speed of 191/min into a spinning bath containing 30% dimethylacetamide and 70% methanol. Next, the swollen fiber precursor was treated with Zr0CAC]214%, H3BO
31.0%, dimethylacetamide 18% and water 67%
The zircon and boron were incorporated into the fiber precursor by passing it through a soaking bath containing: The soaking bath was maintained at a temperature of approximately 25°C. After passing through the soaking bath, 10.
Washing was performed at a speed of 5 m/min. The fibers were then exposed to a hot water drawing solution at 92°C. The fibers are then placed in a water wash bath again for 29 minutes.
．． The 5th fiber was washed at a line speed of 6 m/min and dried at 108°C on heated rolls.The fibers were then stretched at a draw ratio of 2.0:1 in a steam tube maintained at a temperature of 124°C. Next, the fibers were heated to a temperature of 108°C on a heating roll for 30
Heating was carried out at a roll speed of m/min. Analysis of this fiber showed 2.12% zircon and 0.2% boron.

The 1wX fibers were then stabilized by feeding them through a drying process. The feed rate was 8.5 inches/min, and the fibers were dried at 210°C for about 10 minutes, 230°C for about 20 minutes, 255°C for about 70 minutes, 265°C for about 70 minutes, and 275°C for about 70 minutes. The total shrinkage of the fibers after this drying process was 16%.

It was then carbonized in a fiber induction furnace at about 2050° C. for about 2 minutes. The feed rate of fibers to the furnace was 16 nch/min. The atmosphere of the furnace was flushed with nitrogen during the carbonization process.

Carbon fiber has a tensile strength of 232. IKsi, elastic modulus 32
, I Msi (ASTMD3379 and Di577) and elongation of 0.72%. 2 at a temperature of 520°C
After oxidizing for 4 hours (D4102), the tensile strength is 232
, I Ksi , initial elastic modulus was 31.8 MSi, and elongation was 0.76%. Thermogravimetric analysis in air is 700℃
There was a 56% loss of IT after 300 minutes at .

Example 4 Two 300-pore, 100-pore polyacrylonitrile homopolymer dissolved in dimethylacetamide solution
7 or 9 through a micron diameter spinneret? /min into a spinning bath containing 30% dimethylacetamide and 70% methanol. The swollen fiber precursor was then treated with ZrO[AC]218%, )]3BO32,0%,
The zircon and boron 'iff1M fiber precursors were passed through a soaking bath containing 18% dimethylacetamide and 62% water at °C. The soaking bath was maintained at a temperature of 25°C. After passing through the soaking bath, the filament was washed with a 28% aqueous ammonium solution and an additional rinse with water.
Washing was performed at a speed of 0.5 m/min. The fibers were then washed again in a water wash bath at a line speed of 29.6 m/min.

It was dried on heated rolls at 108° C. with a roll speed of 30 m/min. Analysis of the fiber showed 6.9% by weight zircon and 0.30% boron.

The fibers were then stabilized by being fed to a drying process. Feed rate)j is 8.51 nch/min.

Next, the fibers were heated at 210°C for about 10 minutes, at 230°C for about 20 minutes, and at 255°C for about 70 minutes.
℃ for about 70 minutes and 275° C. for about 70 minutes. The total shrinkage of the fiber after this drying process is 16
%Met.

The fibers are then placed in an induction furnace at a temperature of about 2050°C for about 2
Carbonized for minutes. The feeding rate of fiber to the furnace is 16 inch/
It was a minute. The atmosphere in the door was flushed with nitrogen during the carbonization process.

Carbon fiber has a tensile strength of 224.7 KSi and an elastic modulus of 29.4.
M5i (ASTM D3379 and D1577) and elongation of 0.76%. After oxidation for 24 hours at a temperature of 520° C. (ASTM D4102), the tensile strength is 188.6 KSi and the initial modulus is 1 to 29. QMsi.

The elongation was 0.64%. Thermogravimetric analysis showed a 66% loss after 60 minutes at 700° C. in air.

Example 5 16% polyacrylonitrile homopolymer 2-300 pores dissolved in dimethylacetamide solution, 100
It was extruded through a micron diameter spinneret at a rate of 17917 minutes into a spinning bath containing 30% dimethylacetamide and 70% methanol. The swollen fiber precursor is then treated with Ta
0457%.

Tantalum and boron were introduced into the fiber precursor by passing it through a soaking solution containing 838,036%, 18% dimethylacetamide, and 69% methanol. The soaking bath was maintained at a temperature of approximately 25°C. After passing through the soaking bath, the filaments were washed with a 28% aqueous ammonium solution and an additional water rinse at a speed of 10 m/min. The fibers were then exposed to a hot water drawing bath containing a 5% H3Bo3 solution at 87°C.

The fibers were then washed again in a water wash bath at a line speed of 28 m/min and dried on heated rolls at 108°C. The fibers were then placed in a steam tube maintained at a temperature of 124°C for 2.5:
℃ stretching at a stretching ratio of 1.

The fibers were then placed on heated rolls at a temperature of 108°C for 70°C.
Reheating was performed at a roll speed of m/min. Analysis of the fibers showed 4.4% zircon and 2.6% boron.

The fibers were then stabilized by passing them through a drying process.

The feeding rate is 18.51 nch/min, and the fiber is 19
Drying was performed at 5°C for about 10 minutes, at 220°C for about 20 minutes, at 250°C for about 70 minutes, at 230°C for about 70 minutes, and at 275°C for about 70 minutes.

The shrinkage rate of the fiber after this drying process was 16%.

The fibers were then carbonized in an induction furnace at a temperature of about 2,050° C. for about 2 minutes. The feeding rate of fiber to the furnace is IQinch
/minute. The atmosphere of the furnace was flushed with nitrogen during the carbonization process.

Carbon fiber has a tensile strength of 273KSi and an elastic modulus of 36.8i.
itsi (ASTM D3379 and D1577) and elongation of 0.81%. 24 at a temperature of 520°C
After oxidation for an hour (ASTM D4102), the tensile strength was 259.8 KS, the initial modulus was 32.4 MSi, and the elongation was 0.80%. Thermogravimetric analysis in air is 70
After 300 minutes at 0°C it showed a 40% loss of weight.

Example 6 For comparison, an unloaded polyacrylonitrile fiber precursor was prepared at 10°C and processed into carbon fiber. A 916ml dimethylacetamide 1i% polyacrylonitrile homopolymer solution was passed through four 300-hole, IOO micron diameter spinnerets to form polymer 18. It was extruded at a rate of IP/min into a spinning bath containing 30% dimethylacetamide and about 70% methanol. The fibers were then placed on two wash rolls in a water bath for 10.
Washing was performed at a speed of 7 m/min. The fibers were then drawn in a hot gelatin bath maintained at a temperature of 95°C at a draw ratio of 3.3:1. The fibers were then washed twice in a water wash bath.

It was then dried on heated rolls at 108° C. and a roll speed of 155 m/min. The fibers were then stretched at a drawing ratio of 2.3:1 on a hot shoe heated to a temperature of 108°C.
The film was stretched at a final roll speed of 80 m/min.

These fibers were then heated in a furnace at 195°C for 9.8 minutes, 265°C for 22.1 minutes, and 250°C.
The fibers were then stabilized by heating at 230° C. for 2 minutes at CB6.2 minutes and at 275° C. for 95.6 minutes.

Carbonization was performed at a temperature of about 2.050° C. with a feed rate of 20 inch Z. Unloaded carbon fiber has a tensile strength of 32
It showed 2.4 KSi, elastic modulus of 39 MSi, and elongation of 0.82%. After oxidation for 24 hours at a temperature of 520°C, the tensile strength is 149.6 Ksi and the elastic modulus is 36.4 MS.
i, elongation was 410.41%. Thermogravimetric analysis in air showed 98% weight loss after 300 minutes at 700°C.

As is clear from the above description, the filaments produced by this method using a combination of boron and heavy metals have enhanced properties, especially enhanced oxidation, especially after heating and heat resistance. did. Furthermore, the retention of 1 weight/strength was a significant improvement over prior art unloaded fibers or single metal filled fibers.

1990 Patent Application No. 4411 2. Name of the invention Carbon fiber with composite metal Hoechst Celanese Corporation 4th generation Statement printed by type printing

Claims (1)

[Claims] 1. About 98.9% to about 70% by weight of carbon, about 0.1% to about 70% by weight of boron
Approximately 15% by weight and Groups IVB, VB and V of the Periodic Table
A heavy metal selected from the group consisting of Group IB elements from about 0.5 to
Composite metal filled carbon fiber consisting of fiber material containing about 15% by weight. 2. The metal-filled carbon fiber according to claim 1, wherein the heavy metal is tantalum. 3. The metal-filled carbon fiber according to claim 1, wherein the heavy metal is niobium. 4. The metal-filled carbon fiber according to claim 1, wherein the heavy metal is hafnium. 5. The metal-filled carbon fiber according to claim 1, wherein the heavy metal is zircon. 6. Next steps: a. Preparing a polymer filament spinning solution; b. Spinning polymer filaments from the polymer filament solution; c. Treating the polymer filaments with a combination of a boron compound and at least one heavy metal salt. Introducing the heavy metal is selected from the group consisting of elements of Group IVB, Group VB and Group VIB of the Periodic Table; d. Insolubilizing the combination of boron compound and heavy metal salt in the polymer filament to form a fiber precursor. e. stabilizing the fiber precursor; and f. carbonizing the fiber precursor to form a composite boron/heavy metal-containing carbon fiber. 7. The method according to claim 6, wherein the metal is tantalum. 8. The method according to claim 6, wherein the heavy metal is niobium. 9. The method according to claim 6, wherein the heavy metal is hafnium. 10. The method according to claim 6, wherein the heavy metal is zircon. 11. The method of claim 6, wherein the polymer filaments are either acrylonitrile homopolymers or acrylonitrile copolymers. 12. The method of claim 6, wherein the polymer filament spinning solution comprises about 10-30% by weight polymeric material based on the total weight of the solution. 13. The fiber precursor contains about 0.1 to about 5% by weight of a boron compound.
and from about 0.5 to about 15% by weight of a heavy metal salt, wherein the heavy metal is selected from the group consisting of elements of Groups IVB, VB, and VIB of the Periodic Table.