JPH093727A - Boron carbonitride fiber and method for producing the same - Google Patents

Abstract

(57) [Summary] [Structure] An addition product of boron trihalide such as boron trichloride and a nitrile compound such as acetonitrile or benzonitrile, and ammonium chloride or primary amine hydrochloride is treated with boron trihalide. The boron carbonitride precursor obtained by heating at about 125 ° C. in the presence of is dissolved in the precursor-soluble solvent such as N, N′-dimethylformamide, and the precursor fiber is spun from the solution. By heat treatment in an inert gas atmosphere while applying tensile stress, it is composed of boron carbonitride in which carbon, boron and nitrogen are bonded, and its C plane is oriented parallel to the fiber axis and its orientation degree is 0.70 or more, tensile strength of at least 1400M
Boron carbonitride fiber having Pa can be obtained. [Effect] The boron carbonitride fiber of the present invention has an orientation degree of 0.
It is 70 or more, and as a result, the tensile strength is remarkably high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boron carbonitride fiber and a method for producing the same.

[0002]

2. Description of the Related Art Since ceramic materials have high strength and are stable up to high temperatures, they are expected to be applied as high-temperature structural materials that cannot be replaced by plastics and metal materials. However, these materials have excellent thermal,
On the contrary to mechanical properties, it has the property of being essentially brittle and easy to crack.

As a means of overcoming the brittleness of ceramics,
Strengthening of toughness by compounding with a reinforcing material is effective. Spherical particles, plate-like particles, whiskers, continuous fibers, etc. have been investigated as the reinforcing material for composite formation, but among them, toughness enhancement by combining with continuous fibers is effective, and fracture toughness is compared with aluminum alloy. It is known that it can be increased to the same level.

Ceramic fibers typified by silicon carbide fibers and alumina fibers are considered to be one of the candidates for the continuous fiber for composite reinforcement. However, although the structure of the ceramic fiber is a polycrystalline body in which fine crystals are aggregated, when it is exposed to a high temperature, the crystals formed become coarse, and the tensile strength of the fiber is significantly reduced. Generally, when a composite reinforcing fiber is combined with a ceramic, it is necessary to heat the composite reinforcing fiber at a high temperature of several thousand centigrade or more. Therefore, the tensile strength of the ceramic fiber is lowered in the step of forming a composite with the ceramic, and it becomes difficult to achieve toughness enhancement.

On the other hand, boron carbonitride fibers are not susceptible to structural changes such as crystal coarsening even at high temperatures because the boron carbonitride bonding anisotropy is remarkable, and therefore they are exposed to high temperatures. It is estimated that the decrease in the tensile strength of the fiber due to this is small. Since the boron carbonitride fiber has excellent heat resistance as described above, it is extremely useful as a reinforcing fiber.

In addition to the excellent properties as a reinforcing fiber described above, boron carbonitride fiber can be widely controlled from a high conductivity close to that of carbon fiber to a low conductivity close to that of boron nitride fiber. Further, it has a high thermal shock resistance, a high thermal conductivity and an intercalation compound forming ability, and is an industrially extremely useful material.

As a method for producing boron carbonitride fiber, a boron source gas is formed on an iron-based metal substrate by a CVD method,
A method is known in which a carbon source gas and a nitrogen source gas are introduced and pyrolyzed to vapor-deposit boron carbonitride fibers (Japanese Patent Laid-Open No. 1-252520). Boron carbonitride fibers having a length of several microns can be obtained by this method, but the shape is not a needle-like shape peculiar to whiskers, but an irregular shape in which disordered bending is repeated. Further, since the obtained fiber is a short fiber, it cannot be used for the composite reinforcement by the continuous fiber described above.

As a method for producing a boron carbonitride fiber as a continuous fiber, various organic polymer fibers are used as a carbon source or a carbon source and a nitrogen source, and this is reacted with boron halide and calcined to produce boron. A method of producing by introducing is known (JP-A-7-48121). In this method, since the organic polymer fiber is used as a substrate for forming a fiber shape, it is inevitable that only a carbonitride boron boron fiber having a relatively high carbon content of about 50 wt% or more can be obtained, and the nitrogen content is wide. It is difficult to control. Since this boron carbonitride fiber has a limited range of composition control for the reasons described above, it may also have a limited range of conductivity control. Further, in this method, since the organic polymer fiber formed into a fibrous shape by the solid-gas reaction is reacted with the boron source, the boron concentration may be different depending on the surface of the fiber and the inside of the fiber or the position in the fiber axial direction. Uniformity is likely to occur. On the other hand, volatile components are desorbed from the organic polymer fiber as the substrate by heat treatment. When these materials come in and go out, and they occur unevenly, fine defects and stress distributions that induce them are introduced into the fiber, and as a result, the strength of the resulting boron carbonitride fiber is significantly reduced. There is.

[0009]

In the past research on boron carbonitride fibers, the only purpose was to obtain fibrous boron carbonitride, and the crystal orientation of boron carbonitride,
And no consideration was given to its effect on physical properties.

However, since boron carbonitride has a direction in which the strength is extremely weak in terms of crystal structure, this direction exists in parallel to the fiber axis of the boron carbonitride fiber at a certain ratio or more. The strength of the fiber, that is, the conventionally obtained boron carbonitride fiber, was not sufficient.

[0011]

Accordingly, the present inventors have conducted intensive studies from various angles to solve the above-mentioned problems. As a result, we found boron carbonitride fibers in which the C-plane of boron carbonitride was preferentially oriented in the direction parallel to the fiber axis, and as the degree of orientation of this boron carbonitride fiber increased, its tensile strength increased. For the first time, it was discovered that the improvement was dramatic, and the present invention was completed here.

That is, the present invention provides a structure in which a 6-membered ring formed by combining carbon, boron and nitrogen is connected in the plane direction of the 6-membered ring and the surface (C-plane) is laminated. The boron carbonitride fiber is a boron carbonitride fiber having a tensile strength of at least 1400 MPa.

Another invention has a structure in which a 6-membered ring formed by combining carbon, boron and nitrogen is connected in the plane direction of the 6-membered ring and the surface (C-plane) is laminated. A boron carbonitride fiber made of boron carbonitride, wherein at least part of the C plane is oriented substantially parallel to the fiber axis of the boron carbonitride fiber, and the orientation degree of the C plane is Boron carbonitride fiber of at least 0.70.

In still another invention, (a) an adduct of a boron trihalide and a nitrile compound is reacted with an ammonium halide or a primary amine hydrohalide in the presence of boron trihalide. A boron carbonitride precursor is produced, (b) the boron carbonitride precursor is dissolved in a solvent to prepare a boron carbonitride precursor solution, and (c) the boron carbonitride precursor solution is spun. To form a boron carbonitride precursor fiber, and (d) 1600 to 2300 while applying tensile stress to the boron carbonitride precursor fiber in an inert gas atmosphere.
It is a method for producing a boron carbonitride fiber characterized by heating at ℃.

In still another invention, (a) an adduct of a boron trihalide and a nitrile compound is reacted with an ammonium halide or a primary amine hydrohalide salt in the presence of boron trihalide. A boron carbonitride precursor is produced, (b) the boron carbonitride precursor and an acrylonitrile-based polymer are dissolved in a solvent to prepare a boron carbonitride precursor solution, and (c) the boron carbonitride precursor solution. Spinning the precursor solution to form a boron carbonitride precursor fiber, and (d) heating the boron carbonitride precursor fiber at 1600 to 2300 ° C. while applying tensile stress in an inert gas atmosphere. And a method for producing a boron carbonitride fiber.

The above-mentioned boron carbonitride fiber of the present invention and the method for producing the same will be described in detail below.

Boron carbonitride is a substance formed by chemically combining boron of Group III of the periodic table, carbon of Group IV of the periodic table and nitrogen of Group V of the periodic table. (1) A structure formed by three-dimensionally combining carbon, boron, and nitrogen, that is, a boron carbonitride having the same structure as a diamond structure unless the kinds of elements occupying atomic positions are distinguished, and (2 ) A carbon having a structure in which a 6-membered ring formed by combining carbon, boron and nitrogen is connected in the plane direction of the 6-membered ring to form a face (hereinafter referred to as C face), and the C faces are laminated. Boron nitride is known.

In the boron carbonitride according to the present invention, the latter 6-membered ring formed by bonding carbon, boron and nitrogen is condensed and connected in the plane direction of the 6-membered ring to form a plane, Moreover, this surface is made of boron carbonitride having a laminated structure.

The boron carbonitride fiber of the present invention has a structure in which the C-planes maintain regularity between planes, such as the structure of hexagonal boron nitride in boron nitride or the structure of graphite in carbon. Boron carbonitride and / or
For example, it is a fiber made of boron carbonitride having a laminated structure lacking regularity between C planes, such as a turbostratic structure in boron nitride or carbon.

The laminated structure of the boron carbonitride can be confirmed from the diffraction peak from the C plane by X-ray diffraction. This diffraction peak is 2θ = 24 to 26 when the X-ray is CuKα ray.
The distance between the stacked C-planes, which appears at the position of ° and is calculated from the position of the diffraction peak, is about 3 to 4 angstroms.

The boron carbonitride has a structure similar to that of boron carbonitride because it contains carbon-boron and carbon-nitrogen bonds in addition to carbon-carbon and boron-nitrogen bonds. It is distinguished from carbon having a graphite structure or the like and boron nitride having a hexagonal structure or the like or a mixture thereof. The presence of a carbon-boron or carbon-nitrogen bond is represented by X
It can be confirmed by linear photoelectron spectroscopy (also referred to as XPS) or Raman spectroscopy.

In the case of X-ray photoelectron spectroscopy, the XPS spectrum of boron bound to carbon is X-ray of boron bound to nitrogen.
It shifts to a lower energy side than the PS spectrum. On the other hand, the XPS spectrum of nitrogen bonded to carbon shifts to a higher energy side than the XPS spectrum of nitrogen bonded to boron. Therefore, by measuring the XPS spectra of boron and nitrogen in boron carbonitride by X-ray photoelectron spectroscopy, the carbon-boron bond and carbon-nitrogen bond in the boron carbonitride can be confirmed.

Further, according to Raman spectroscopy, carbon - carbon bond composed only of graphite and boron - Raman spectra of hexagonal boron nitride comprising only nitrogen bond each 1570 cm ^-1, peak at 1370 cm ^-1 In contrast to boron carbonitride containing carbon-boron bond and carbon-nitrogen bond, about 1430 cm in between.
A spectrum having a peak at a position centered at ^-1 is obtained.

The composition of the boron carbonitride fiber of the present invention is not particularly limited, but preferably, in the boron-carbon-nitrogen ternary phase diagram, the composition of boron is 9 at 1 atm% or more.
0 atm% or less, a carbon composition of 2 atm% or more and 98 atm% or less, and a nitrogen composition of 1a.
It is a composition contained in a region (hereinafter also referred to as region A) corresponding to a product set with a region of tm% or more and 60 atm% or less, and more preferably, in the ternary phase diagram of boron-carbon-nitrogen, carbon 100 atm% points and 80 atm boron
A straight line connecting the points of m% -nitrogen 20 atm% and carbon 100
Atm% point and Boron 20 atm% -Nitrogen 80 atm%
Is a composition contained in a region corresponding to a product set of the region A and a region surrounded by a straight line connecting the points. More preferably, in a ternary phase diagram of boron-carbon-nitrogen, carbon 100 atm% Point and boron 80atm% -nitrogen 20a
The composition contained in the region corresponding to the intersection of the region A and the region surrounded by the straight line connecting the points of tm%, the line connecting the points of 100 atm% of carbon and the points of 40 atm% of boron and 60 atm% of nitrogen. And most preferably boron-carbon-
In the ternary phase diagram of nitrogen, a straight line connecting a point of 100 atm% carbon and 60 atm% of boron-40 atm% of nitrogen, and a point of 100 atm% of carbon and 40 atm% of boron-
A region surrounded by a straight line connecting the points of 60 atm% nitrogen,
It is the composition contained in the region corresponding to the intersection with the region A.

Boron carbonitride fibers having a high carbon content can be produced by a method such as increasing the amount of an acrylonitrile polymer added to a boron carbonitride precursor solution (hereinafter also referred to as a spinning solution). Boron carbonitride fibers having a low carbon content can be produced by a method such as heating boron carbonitride precursor fibers in ammonia. At this time, the carbon content can be controlled by conditions such as the heating temperature of the heat treatment in ammonia.

The most important thing in the present invention is that the C-plane of boron carbonitride is preferentially oriented in the direction parallel to the fiber axis of boron carbonitride fiber.

The present inventor has for the first time found a boron carbonitride fiber in which the C-plane of boron carbonitride is oriented parallel to the fiber axis. Further, it was also found for the first time that when the degree of this orientation is improved, the tensile strength of the obtained boron carbonitride fiber is improved at a certain degree or more. Boron carbonitride C
The reason why the tensile strength is improved by orienting the surface parallel to the fiber axis is presumed as follows. In the case of boron carbonitride, the bond in the C-plane is determined by analogy with the similarity of the crystal structures of graphite and hexagonal boron nitride.
While the covalent bond is strong and the bond is strong, the bond between the faces is considered to be a weak bond mainly due to van der Waals force. Therefore, it is estimated that the tensile strength increases as the ratio of the strong in-plane bonds parallel to the fiber axis increases. When the C-plane of boron carbonitride is isotropically distributed with respect to the fiber axis, carbonitride boron nitride is present due to the presence of boron carbonitride crystals whose direction perpendicular to the C-plane is parallel to the fiber axis direction. It is estimated that the tensile strength of the raw fibers is limited and it is difficult to increase the strength. It is considered that this estimation is supported by the fact that the strength is improved as the C plane of boron carbonitride is oriented in the direction parallel to the fiber axis.

The previous researches on boron carbonitride fibers are aimed only at obtaining fibrous boron carbonitride, and pay attention to the crystal orientation of boron carbonitride and its influence on the physical properties. I didn't.

The degree of orientation of the C-plane (hereinafter also referred to as orientation degree) is used as an index representing the orientation distribution of the C-plane of boron carbonitride with respect to the fiber axis of the boron carbonitride fiber. The boron carbonitride fiber in the present invention is characterized in that the degree of orientation is 0.70 or more. In reality, the inventor has found that the degree of orientation is 0.7.
Boron carbonitride fibers that are less than 0 can also be found and manufactured. For example, a boron carbonitride fiber having an orientation degree of less than 0.70 can be produced by heating a boron carbonitride precursor fiber without applying tensile stress. However, when boron carbonitride fibers having various degrees of orientation were manufactured and the tensile strength of the boron carbonitride fibers against the degree of orientation was systematically investigated, it was found that the degree of orientation was less than 0.7. The tensile strength of is substantially independent of the degree of orientation, and its value is low. On the other hand, when the degree of orientation is 0.7 or more, the tensile strength of the boron carbonitride fiber shows a remarkable improvement. For example, when the typical values are shown, the tensile strengths of boron carbonitride fibers having orientations of 0.55 and 0.66 are 44
While 0 MPa and 900 MPa, the degree of orientation is 0.
The tensile strength of the boron carbonitride fiber No. 82 was 1900 MPa.

When the orientation degree is 0.7 or more, the tensile strength of the boron carbonitride fiber is improved in proportion to the orientation degree. For example, as a representative value, when the orientation degree is 0.74, the tensile strength is 1700 MPa, whereas when the orientation degree is 0.82, the tensile strength is improved to 1900 MPa. Furthermore, the tensile strength is 2200MP by adjusting the degree of orientation to 0.85.
improved to a. Therefore, when the orientation degree is 0.70 or more, the tensile strength can be further improved by improving the orientation degree.

The boron carbonitride fibers of the present invention have a tensile strength of at least 1400 MPa, preferably at least 17
00 MPa, most preferably at least 1900 MPa
belongs to.

The above-mentioned tensile strength is JIS R 7601.
(1986) "Testing method of carbon fiber"
Can be measured according to.

The boron carbonitride fibers of the present invention also have a degree of orientation of at least 0.70, preferably at least 0.7.
4, most preferably at least 0.82.

As the effect of orientation, in addition to improving the tensile strength, it is possible to improve the thermal conductivity in the fiber axis direction. In the case of graphite having a structure similar to that of boron carbonitride, the thermal conductivity in the in-plane direction is higher than the thermal conductivity in the in-plane direction of the single crystal carbon 6-membered ring. It is known to take Similarly, in the case of boron nitride, which is similar to boron carbonitride, the heat of boron nitride obtained by regularly stacking the faces formed by the boron-nitrogen 6-membered ring of boron nitride by the chemical vapor phase method. When the conductivity is measured, the thermal conductivity in the in-plane direction is nearly 100 times higher than the thermal conductivity in the direction perpendicular to the plane. Further, it is known that in the case of carbon fibers in which the 6-membered carbon ring is preferentially oriented in the direction parallel to the fiber axis, the thermal conductivity improves as the degree of orientation improves. In graphite and boron nitride containing carbon fibers, the reason for the high thermal conductivity in the in-plane direction is that relatively light elements such as carbon, boron and nitrogen are bonded to each other by a strong covalent bond, It is thought that this is because heat is efficiently propagated by vibration. The fact that the relatively light element is strongly bonded by covalent bonding is the same in boron carbonitride. Therefore, even in boron carbonitride, it is considered that the thermal conductivity in the in-plane direction of the C plane is higher than that in the in-plane direction. As a result, as in the case of carbon fiber, it is considered that the thermal conductivity in the fiber axis direction is improved as the degree of orientation of the boron carbonitride fiber is improved.

As the effect of orientation, in addition to improving the tensile strength and the thermal conductivity in the fiber axis direction, efficient intercalation can be mentioned. It is known that lithium ions or the like are inserted between layers of boron carbonitride to form an intercalation compound. Therefore, boron carbonitride is expected to be used as a negative electrode active material for Li secondary batteries. In the boron carbonitride fiber in the present invention,
The C plane of boron carbonitride is preferentially oriented in the direction parallel to the fiber axis. That is, it can be said that the layers into which lithium ions or the like are to be inserted are parallel to the fiber axis direction. Therefore, it is considered that intercalation easily occurs in the fiber axis direction and the battery performance can be improved as compared with the case of using boron carbonitride having an isotropic C plane.

The degree of orientation described above can be determined by an X-ray diffraction method based on the X-ray intensity distribution on the Debye ring generated by the diffraction from the C plane of boron carbonitride. Hereinafter, a method for measuring the degree of orientation by the X-ray diffraction method will be described.

As X-rays used for diffraction, copper Kα rays monochromated by a nickel filter (hereinafter referred to as CuKα rays) are used, and the diffraction intensity is measured by the transmission method.
Also, in order to obtain diffraction with high efficiency for X-ray output,
The X-ray source is preferably a point focus.

A sample to be subjected to X-ray diffraction, in which tens or hundreds of boron carbonitride fibers are bundled so that the carbonitride boron fibers are as parallel as possible and fixed with a small amount of collodion or the like. And Hereinafter, this is referred to as an X-ray diffraction test piece.

The diffraction intensity may be measured either by taking a photograph of a diffraction image or by using an X-ray diffractometer.

When the diffraction intensity is measured by taking a photograph of a diffraction image, the fiber axis of the boron carbonitride fiber of the X-ray diffraction sample is in the plane perpendicular to the incident X-ray. The X-ray diffraction sample is fixed so that the incident X-rays irradiate the boron carbonitride fiber bundle of the X-ray diffraction sample. At this time, the incident X
The direction of the fiber axis of the boron carbonitride fiber of the X-ray diffraction specimen in a plane perpendicular to the line may be any direction as long as the direction relative to the diffraction image can be specified. However,
Here, it is assumed that the fiber shaft is fixed vertically for explanation.

An X-ray photosensitive film for photographing a diffraction image is placed on the side opposite to the direction of the incident X-ray with respect to the X-ray diffraction specimen. The X-ray sensitive film should be perpendicular to the direction of the incident X-ray. The distance from the X-ray diffraction specimen to the X-ray photosensitive film (hereinafter also referred to as camera length) is determined by the diffraction from the C-plane of boron carbonitride constituting the boron carbonitride fiber of the X-ray diffraction specimen. The distance must be such that the entire Debye ring can be photographed. The radius (D) of the Debye ring on the X-ray photosensitive film can be obtained by equation (1).

D = L × tan (2θ) (1) Here, L is the camera length, 2θ is the Bragg's angle with respect to the C plane of boron carbonitride constituting the boron carbonitride fiber of the X-ray diffraction specimen. It is a diffraction angle that satisfies the diffraction condition. In the case of the boron carbonitride fiber, if the incident X-ray is CuKα ray, 2θ is 24 to 2
In the range of 6 °. Therefore, the camera length L may be set so that a circle having a radius D centered on the intersection of the direction of the incident X-ray and the X-ray photosensitive film is contained in the X-ray film.

The diffracted X-ray intensity mainly varies depending on the amount of boron carbonitride fiber of the X-ray diffraction test piece, the crystallite diameter of boron carbonitride constituting the boron carbonitride fiber, and the like. In order to obtain a diffraction image, it is necessary to adjust the X-ray exposure time. If the exposure time is too long, the intensity of the diffracted X-rays will not be proportional to the degree of blackening of the X-ray photosensitive film due to the diffracted X-rays. Also appears relatively weakly, and an accurate degree of orientation cannot be obtained. Also, if the exposure time is too short,
Since the S / N ratio of the degree of blackening due to the diffracted X-rays of the X-ray photosensitive film decreases, the error of the obtained degree of orientation increases. In order to confirm whether the exposure time is appropriate or not, the same X-ray diffraction specimen can be obtained by changing the exposure time and photographing a diffraction image to confirm that the obtained degree of orientation does not change. .

When the exposed X-ray photosensitive film is developed,
The portion irradiated by the diffracted X-ray turns black in proportion to the intensity of the diffracted X-ray. Therefore, the intensity of the diffracted X-ray can be obtained by quantifying the degree of blackening of the film using a microdensitometer. When the C plane of boron carbonitride is oriented parallel to the fiber axis direction of the boron carbonitride fiber, X
A direction perpendicular to the fiber axis of the boron carbonitride fiber of the sample for X-ray diffraction, passing through the center of the Debye ring (the intersection point of the incident X-ray and the X-ray photosensitive film) on the Debye ring photographed on the line-sensitive film. The blackening degree of the film (hereinafter, also referred to as the equatorial line direction) becomes maximum, passes through the center of the Debye ring, and is parallel to the fiber axis of the boron carbonitride sample of the X-ray diffraction sample (hereinafter, also referred to as the meridian direction). The diffraction intensity distribution that minimizes the degree of blackening of the film is generated. The position of the diffraction intensity measurement point on the Debye ring is determined by the central angle φ from the reference point on the Debye ring,
As a function thereof, the intensity of the diffracted X-ray on the Debye ring is obtained. At this time, the X-ray intensity on the Debye ring is the sum of the intensity of the diffracted X-ray from the C-plane of the boron carbonitride fiber and the intensity of the background. Therefore, in order to determine the net diffracted X-ray intensity from the C-plane, the background intensity in the Debye ring is determined by measuring the change in the X-ray intensity in the radial direction of the Debye ring, and this is used as the X-ray intensity in the Debye ring. Subtract from When the intensity of the diffracted X-ray from the C plane is obtained as a function of the central angle φ, two peaks having local maxima at positions corresponding to the equator direction are obtained. For each peak, the half width is measured in degrees, and the average (H) is calculated. Using the obtained H, the degree of orientation (π) can be calculated by the formula (2) [Carbon Material Society of Japan, "Development and Evaluation Method of Carbon Fiber", page 118 (198).
9). ].

Π = (180−H) / 180 (2) An X-ray diffractometer can be used to measure the diffraction intensity. Known diffractometers can be used,
Hereinafter, a diffractometer in which the axis of the diffractometer is vertical and the scanning surface of the X-ray counter is horizontal will be described. When using an X-ray diffractometer, the X-ray diffraction sample can be fixed and
A fiber sample stage having a mechanism capable of rotating the X-ray diffraction specimen 360 degrees in a plane perpendicular to the line is used.

First, the diffraction angle of the C-plane of boron carbonitride constituting the boron carbonitride fiber of the X-ray diffraction test piece satisfying the Bragg diffraction condition is determined by the transmission method. X on the fiber sample table
The sample for line diffraction is fixed, and the fiber axis of the boron carbonitride fiber of the sample for X-ray diffraction is fixed vertically. In this state, the X-ray is incident, and the X-ray counter, that is, the 2θ of the diffractometer is scanned and the diffraction X
Measure the line strength. Since the diffraction of boron carbonitride on the C-plane usually occurs at 2θ of 24 to 26 degrees, the angle at which the intensity of the diffracted X-ray shows the maximum is obtained in this angle range. This angle is the diffraction angle of the C plane.

Next, the X-ray counter tube was fixed at the diffraction angle of the C plane, the X-rays were made incident, and the X-ray diffraction specimen fixed on the fiber sample table was set 360 in the plane perpendicular to the incident X-rays. Rotate by degrees and measure the corresponding diffracted X-ray intensity. Now, the rotation angle of the X-ray diffraction specimen is α (however, the unit is degree), and α is 0 degree when the fiber axis of the boron carbonitride fiber of the X-ray diffraction specimen is vertical. When the C-plane of the boron carbonitride constituting the boron carbonitride fiber of the X-ray diffraction specimen is oriented in the fiber axis direction of the boron carbonitride fiber, α is diffracted to 0 ° and 180 °. A peak having a maximum of the X-ray intensity appears. At this time, it is necessary to correct the intensity of the diffracted X-ray by subtracting the intensity of the background, as in the method of taking a photograph of the diffraction image described above.
For each peak, the half width was measured in degrees, and the average (H) was used to determine the degree of orientation (π) from equation (2).
Can be calculated.

The method for producing the boron carbonitride fiber of the present invention having a high tensile strength and a high degree of orientation is not particularly limited, but it can be typically produced as follows.

(A) First, an adduct of a boron trihalide and a nitrile compound is reacted with an ammonium halide or a primary amine hydrohalide in the presence of boron trihalide to produce boron carbonitride. Generate a precursor.

Examples of the boron trihalide include boron trifluoride, boron trichloride, boron tribromide and boron triiodide, which can be used without particular limitation.

As the nitrile compound, known compounds having a nitrile group can be used without particular limitation. Specifically, acetonitrile, propionitrile, capronitrile, acrylonitrile, crotonnitrile,
Tolunitrile, benzonitrile, i-butyronitrile,
Examples include n-butyronitrile, isovaleronitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronitrile, suberonitrile and the like. When the number of carbon atoms contained in the nitrile compound increases,
The amount of carbon contained in the boron carbonitride precursor is increased, and the amount of carbon contained in the boron carbonitride fiber obtained by the heat treatment can be increased.

As ammonium halides, ammonium fluoride, ammonium chloride, ammonium bromide,
Ammonium iodide and the like can be mentioned. Preferred examples of the ammonium halide include ammonium chloride.

As the primary amine hydrohalide,
Primary amine hydrofluoride, primary amine hydrochloride,
Primary amine hydrobromide, primary amine hydroiodide and the like can be mentioned. Preferred examples of the primary amine hydrohalide include primary amine hydrochloride (hereinafter, referred to as primary amine hydrochloride).
Primary amine hydrochloride).

The primary amine hydrochloride has the general formula: RNH ₂
A compound represented by HCl, in which R is an alkyl group such as a methyl group, an ethyl group and a propyl group, and an aryl group such as a phenyl group, a tolyl group and a xylyl group is used without limitation.
When the number of carbon atoms of R increases, the amount of carbon contained in the boron nitride precursor increases, and the amount of carbon contained in the boron carbonitride fiber obtained by the heat treatment can be increased.

To obtain the boron nitride fiber of the present invention,
First, a boron nitride precursor is synthesized by reacting an adduct of the boron trihalide and the nitrile compound with an ammonium halide or a primary amine hydrohalide.

The adduct of the boron trihalide and the nitrile compound is a product in which the boron halide is additionally bonded to the non-bonded electron pair of the nitrogen atom of the nitrile group, and the boron trihalide and It easily reacts with a nitrile compound to form an adduct. The method for producing the adduct is not particularly limited. For example, a method of dropping boron trihalide into a solution of a nitrile compound in an organic solvent at room temperature, a method of dissolving a nitrile compound in an organic solvent and then blowing boron trihalide, or a method of trihalogenating the organic solvent An adduct can be formed by dissolving boron and then dropping a nitrile compound.
Since boron trihalide and the nitrile compound easily react to form an adduct, they may be brought into contact with each other immediately before the reaction.

It is essential that boron trihalide be present during the reaction of the adduct with ammonium halide or primary amine hydrohalide. When boron trihalide is not present during the reaction, the yield of the boron nitride precursor of the present invention is low, and a spinning solvent for spinning as described later, such as N, N-dimethylformamide (hereinafter referred to as DMF).
(Also referred to as) insoluble reaction by-products are generated.

The boron trihalide may be present at least during the reaction between the boron trihalide / addition product of the nitrile compound and the ammonium halide or the primary amine hydrohalide. For example, when an adduct of a nitrile compound and boron trihalide is formed, excess boron trihalide may be used, and unreacted boron trihalide may be allowed to coexist in the adduct in advance. good. The amount of boron trihalide to be added to the nitrile compound is 1.05 to 5 in molar ratio (boron trihalide / nitrile compound).
It can be arbitrarily selected from the range of 2.00. But,
When the amount of boron trihalide added is small, a DMF-insoluble component is produced, and when the amount of boron trihalide added is large, the amount of boron trihalide that does not contribute to the reaction increases, so trihalogen for a more preferable nitrile compound is used. The addition molar ratio of boron bromide is 1.1 to 1.5. At this time, since the boron trihalide and the nitrile compound form a 1: 1 adduct, the amount of boron trihalide present during the reaction is in a molar ratio (boron trihalide / addition). In the range of 0.1) to 0.5).

The concentration of the nitrile compound in the reaction solvent is not particularly limited, but it is preferably in the range of 0.1 to 10 mol / l. When the concentration of the nitrile compound is less than 0.1 mol / l, the amount of the obtained boron nitride precursor is small, which is not preferable because it is not efficient.
On the other hand, if the concentration of the nitrile compound exceeds 10 mol / l, the amount of the adduct formed as a solid with respect to the solvent becomes too large, and the formation of the adduct becomes ununiform.

The amount of the ammonium halide or the primary amine hydrohalide salt added is 0.67 to a molar ratio to the nitrile compound (ammonium halide or primary amine hydrohalide salt / nitrile compound).
It is preferable to select from the range of 1.5. When the amount of ammonium halide or primary amine hydrohalide is large, a component insoluble in DMF is generated, and when the amount of nitrile compound is large, the amount of unreacted adduct tends to increase. What is necessary is just to choose from the range of -1.2.

The solvent used for synthesizing the boron carbonitride precursor of the present invention is not particularly limited, but when the boron carbonitride precursor which is a reaction product is separated, a borazine compound which is a reaction by-product is used. It is preferably dissolved and easily removed. From such a viewpoint, an organic solvent such as benzene, toluene, xylene, chlorobenzene is preferably selected.

The heating temperature for reacting the adduct with the ammonium halide or the primary amine hydrohalide is generally low at low temperatures and D at high temperatures.
Components insoluble in MF increase and the reaction yield decreases. Therefore, the heating temperature may be selected from the range of 100 ° C to 160 ° C. The heating time varies depending on the temperature, but may be selected from the range of 3 to 30 hours.

By performing the above heat treatment, the boron nitride precursor is formed as an orange or brown precipitate.

As a reaction device for obtaining the boron nitride precursor, a known device can be used without particular limitation. However, since the adduct of boron trihalide with the nitrile compound and the boron nitride precursor are both hydrolyzed, the inside of the reaction system is sufficiently dried in advance with nitrogen gas or the like, and air is also supplied from outside the reaction system during the reaction. It is necessary to provide a moisture absorbent such as calcium chloride in the opening portion of the apparatus so that moisture in the apparatus does not enter.

(B) The boron carbonitride precursor produced in step (a) is dissolved in a solvent to prepare a boron carbonitride precursor solution.

This boron carbonitride precursor solution can be used as a spinning solution in the next step (c).

As a method for producing a boron carbonitride precursor fiber from this boron carbonitride precursor, a known method can be used without particular limitation. For example, when spinning a precursor fiber from a boron carbonitride precursor solution, the spinning solution is prepared by dissolving the boron carbonitride precursor in a soluble solvent. Examples of the precursor-soluble solvent include DMF and ε
-Caprolactam, chloronitrile, malonitrile, N
-Methyl-β-cyanoethylformamide, N, N-
Examples thereof include diethylformamide. By dissolving the boron carbonitride precursor in the soluble solvent, an orange or brown transparent spinning solution can be obtained.

The viscosity of the spinning solution can be adjusted, if desired, by adding, for example, an acrylonitrile polymer. When the molecular weight of the boron carbonitride precursor is relatively small, the viscosity of the spinning solution is increased by using an acrylonitrile polymer having a relatively large molecular weight together with the boron carbonitride precursor, and the spinnability of the spinning solution is increased. Can be improved.

The acrylonitrile-based polymer used in the present invention is dissolved in a soluble solvent constituting the spinning solution and does not cause phase separation with the boron carbonitride precursor in the spinning solution.
It can be used without particular limitation. Preferably, a polymer of acrylonitrile, or a polymerizable monomer other than acrylonitrile having a vinyl group such as vinyl acetate, acrylamide, methacrylic acid, methacrylic acid ester, acrylic acid, acrylate (hereinafter, simply referred to as vinyl monomer) and acrylonitrile Is used.
When a copolymer of acrylonitrile and a vinyl monomer is used, an increase in the amount of the vinyl monomer constituting the copolymer causes phase separation with the boron carbonitride precursor in the spinning solution. Since there is a tendency, the composition of acrylonitrile constituting the copolymer is 8 based on the total polymerizable monomer.
It is preferably 5 mol% or more.

The weight average molecular weight of the acrylonitrile polymer used in the present invention is not particularly limited, but it is 10,000 to 20.
It is preferably in the range of 10,000.

The amount of the acrylonitrile polymer added to the spinning solution is not particularly limited, but it is not intended to produce the above-mentioned boron carbonitride fiber having a high carbon content, but the spinnability of the spinning solution. For the purpose of improving the above, 0.01 to 5 parts by weight may be used with respect to 100 parts by weight of the boron carbonitride precursor.

(C) The boron carbonitride precursor solution prepared in step (b) is spun to form boron carbonitride precursor fibers.

The preferred concentration range of the spinning solution depends on the spinning method, but is 0.01 to 3.0 g / ml, and the viscosity at that time is 10 to 100,000 poises. The method for spinning the boron carbonitride precursor fiber from the obtained spinning solution is
A widely known method can be used. For example, by rotating a container having a small hole containing the spinning solution, the spinning solution is discharged by using centrifugal force, the spinning solution is discharged by gas pressure through the small hole, and a gear pump is used through the small hole. The boron carbonitride precursor fiber can be spun using a method such as discharging a spinning solution.

The spinning temperature may vary depending on the solvent used, but is, for example, -60 to 200 ° C, preferably -10 to 10.
The temperature is 180 ° C, more preferably 0 to 160 ° C.

One of the methods for obtaining a boron mononitride fiber having an orientation degree of 0.70 or more is a method of heating a boron carbonitride precursor fiber while applying stress.

(D) The boron carbonitride precursor fiber obtained in step (c) is heated at 1600 to 2300 ° C. under an inert gas atmosphere while applying a tensile stress to the boron carbonitride precursor fiber of the present invention. Fibers are obtained.

That is, for the boron carbonitride fibers having an orientation degree of 0.70 or more, the boron carbonitride precursor fibers are placed in an inert gas atmosphere while applying a tensile stress to the fibers, 1600 to 2
It can be obtained by heat treatment at 300 ° C, preferably 1650 to 2250 ° C, more preferably 1700 to 2200 ° C.

Nitrogen, argon, helium, or the like can be used as the atmospheric gas in the heat treatment under the inert gas atmosphere.

The heating device for performing the heat treatment of the boron carbonitride precursor fiber in an inert gas atmosphere may have a structure capable of controlling the atmosphere by a chamber or a furnace core tube. A known heating device such as a furnace can be used without particular limitation. As the heat treatment method, a batch-type heat treatment in which a certain amount of boron carbonitride precursor fibers are heat-treated at one time, and continuous boron carbonitride precursor fibers are sequentially fed to a heating device which has been heated to a heat treatment temperature in advance. In the present invention, any heat treatment method may be used. When performing batch type heat treatment in an inert gas atmosphere, the boron carbonitride precursor fiber is introduced into the heat treatment apparatus which has been preheated to the heat treatment temperature for heat treatment, or the heat treatment apparatus is used. After arranging the boron carbonitride precursor fibers, the temperature can be raised to reach the heat treatment temperature for heat treatment.

In any one of the heat treatment methods, when the boron carbonitride precursor fiber is rapidly heated, DMF which is a solvent for producing a spinning solution from the boron carbonitride precursor is rapidly evaporated, Desorption of thermal decomposition products occurs rapidly,
Defects such as voids and cracks may occur in the obtained boron carbonitride fiber, resulting in a decrease in strength. Therefore, it is preferable to perform the heat treatment at a temperature rising rate of 100 ° C./min or less until the boron carbonitride precursor fiber reaches the heat treatment temperature. The holding time at the heat treatment temperature depends on the amount of boron carbonitride precursor fibers and the heat treatment temperature, but is 0 to 10
It can be arbitrarily selected from the range of time. Hold time is 0
Immediately after the boron carbonitride precursor fiber reaches the heat treatment temperature, the time means that the heat treatment is finished by lowering the temperature of the heating device or taking out the boron carbonitride precursor fiber from the heating device. Show.

In the heat treatment atmosphere in the heat treatment under the inert gas atmosphere, the heat treatment process until reaching the heat treatment temperature, the holding process at the heat treatment temperature, and the temperature lowering process until the end of the heat treatment are all performed. That is, while the boron carbonitride precursor fiber is in the chamber of the heating device, the furnace core tube, or the like in the inert gas atmosphere, the inert gas atmosphere is preferable. In order to make the atmosphere of the inert gas, the chamber of the heating device replaced with the inert gas, the furnace tube or the like is sealed, or the chamber of the heating device,
An inert gas may be passed through a furnace tube or the like.

The heat treatment temperature in the heat treatment is 1600.
２2300 ° C. can be arbitrarily selected. When the heat treatment temperature is lower than 1600 ° C., even when a tensile stress is applied, the crystal orientation does not sufficiently proceed, and the degree of orientation may not reach 0.7. Further, since the decomposition reaction of boron carbonitride starts at 2300 ° C or higher, it is not preferable to perform the heat treatment at 2300 ° C or higher.

The method of applying tensile stress to the boron carbonitride precursor fiber in the heat treatment is not particularly limited,
For example, when the heat treatment is performed in a batch method, the tensile stress can be applied by suspending the boron carbonitride precursor fiber in the vertical direction and adding a weight to the lower end thereof. Further, when the boron carbonitride precursor fiber is heat-treated at 1600 to 2300 ° C. in an inert gas atmosphere without applying a tensile stress, it shrinks in the fiber axis direction depending on the heat treatment temperature. Therefore, the boron carbonitride precursor fiber is attached with a form made of a material such as boron carbonitride precursor fiber and boron carbonitride fiber that does not react with the boron carbonitride fiber produced by heat treatment, and In an inert gas atmosphere, 1600
Heat treatment to ˜2300 ° C. prevents heat shrinkage of the boron carbonitride precursor fiber due to the heat treatment due to the mold, and as a result heat treatment is performed while applying tensile stress to the boron carbonitride precursor fiber. You can When the heat treatment is performed in a continuous manner, the boron carbonitride precursor fiber is supplied to the heat treatment apparatus and the winding speed of the fiber after the heat treatment is controlled to control boron carbonitride. The heat shrinkage of the precursor fiber during the heat treatment can be controlled, and as a result, the heat treatment can be performed while applying the tensile stress.

The tensile stress applied to the boron carbonitride precursor fiber in the heat treatment varies depending on the heat treatment temperature and the heat treatment time of the heat treatment, but is 0.1 when the stress is applied by suspending a weight. It can be arbitrarily selected within a range of up to 1000 MPa. If the applied stress is less than 0.1 MPa, the crystal orientation may be insufficient and the degree of orientation may not reach 0.7. If the applied stress is larger than 1000 MPa, the unoriented fiber may be broken. on the other hand,
When the tensile stress is applied to the boron carbonitride precursor fiber by limiting the shrinkage of the boron carbonitride precursor fiber due to the heat treatment,
Alternatively, by controlling the rate at which the boron carbonitride precursor fiber is fed to the heat treatment apparatus and the rate at which the heat-treated fiber is wound in a continuous process, the thermal contraction due to the heat treatment is limited to limit boron carbonitride. When applying tensile stress to the precursor fiber,
The stretching ratio may be selected from the range of 4 to 32%. However, the stretching ratio (E) is defined by the formula (3).

E = 100 × (Ls−Lf) / Lf (3) Lf does not limit the thermal shrinkage of the boron carbonitride fiber of unit length, that is, the tensile stress is applied to the boron carbonitride fiber. Without heat treatment at a heat treatment temperature (T ° C), Ls represents the length of the fiber sample, and Ls is a fiber obtained by heat treatment at a heat treatment temperature (T ° C) by limiting the heat shrinkage of the boron carbonitride fiber having a unit length. Indicates the sample length.

If the stretching ratio is less than 4%, the tensile stress applied to the boron carbonitride precursor fibers may be insufficient and the crystal orientation degree may not reach 0.70. If the stretching ratio is higher than 32%, the boron carbonitride precursor fiber may be broken during the heat treatment.

[0087]

EFFECTS OF THE INVENTION According to the present invention, it is possible to produce a boron carbonitride fiber which has boron carbonitride as a main component and whose C plane is oriented parallel to the fiber axis and whose degree of orientation is 0.70 or more. You can As a result, boron carbonitride fibers with significantly improved tensile strength can be manufactured. This allows
In addition to the heat resistance inherent in boron carbonitride, it has become possible to manufacture boron carbonitride fibers that also have high strength. Therefore, the boron carbonitride fiber of the present invention can be applied as an excellent composite reinforcing fiber for improving the toughness of ceramic materials and the like.

[0088]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited thereto.

Example 1 A stirrer was attached to the inner tube of a three-necked flask having a capacity of 1 liter, a Dewar cold finger in which a cylinder containing boron trichloride was connected to one of the side tubes, and a ball containing cooling tube was attached to the remaining side tubes. I installed each. A dewar type cold finger was attached to the ball inlet cooling tube, and a calcium chloride tube was attached to the outlet of the cold finger. Dry nitrogen was passed through this device at 200 ml / min for 4 hours to dry the inside of the device.
Chlorobenzene 30 dried over anhydrous sodium sulfate overnight
0 ml and acetonitrile 16.4 g were added. Fill two cold fingers with dry ice-acetone and stir with a stirrer, 60 g of boron trichloride from the cold finger directly attached to the three-necked flask.
Was condensed and added dropwise over 2 hours. This produced a white boron trichloride-acetonitrile adduct. After finishing dropwise three boron chloride-containing, disconnect ^Ri preparative cold finger attached directly to the three-necked flask, were added overnight dry ammonium chloride 21.5g at 110 ° C.. When this suspension was heated to 125 ° C. for 8 hours, generation of hydrogen chloride almost disappeared, and a brown precipitate was formed. The formed precipitate was filtered off, washed with 100 ml of chlorobenzene and dried under reduced pressure to obtain 24 g of boron carbonitride precursor (yield 83%).

10 g of this boron carbonitride precursor was added to DMF2.
After dissolving in 00 ml, 100 ml of DMF was removed by evaporation to obtain a uniform viscous solution. 25 this solution
15kg from spinning nozzle with 60μm diameter hole at ℃
A back pressure of / cm ² was applied, the mixture was discharged into dry air, and wound up to spin a continuous boron carbonitride precursor fiber having a diameter of about 20 μm. At this time, the viscosity of the spinning solution was 2.9 × 10 ⁴ poise and the spinning speed was 1.8 m / min.
Met.

The spun boron carbonitride precursor fiber was wound into a loop with a circumference of 192 mm, and while keeping the loop shape, it was hung on a boron nitride mold with a circumference of 135 mm, and heat-treated in a nitrogen stream as it was. went. Heat treatment is 400
Temperature rising rate up to ℃ 1 ℃ / min, 400 ℃ to 1600
Temperature rising rate up to 2 ° C / min from 1600 ° C to 180 ° C
The temperature is raised up to 0 ° C at a heating rate of 10 ° C / min,
Hold at 30 ℃ for 30 minutes, 500 ℃ at cooling rate of 5 ℃ / min
It was cooled to room temperature and then allowed to cool to room temperature. After treatment,
The boron carbonitride fiber was kept wrapped around the form without breaking or unraveling. The stretching ratio at this time is 6.3%
Met.

From the powder X-ray diffraction and the XPS spectra of boron and nitrogen, the obtained boron carbonitride fiber had a structure in which the C planes were laminated, and the structure had boron-carbon bonds and nitrogen. -It was confirmed that carbon bonds were present.
As a result of elemental analysis of this boron carbonitride fiber,
The composition was 44 atm% boron, 16 atm% carbon, and 40 atm% nitrogen.

The orientation degree of this boron carbonitride fiber is 0.7.
2. The tensile strength was 1400 MPa.

Example 2 Boron carbonitride precursor fibers produced in the same manner as in Example 1 were wound into a loop shape having a circumference of 192 mm, and while keeping the loop shape, a boron nitride mold having a circumference of 131 mm was formed. Then, it was heat treated in a nitrogen stream as it was. The heat treatment is performed at a heating rate of 1 ° C / min up to 400 ° C, and a heating rate of 2 ° C / min at 1600 ° C from 400 ° C to 1600 ° C.
To 2000 ° C at a heating rate of 10 ° C / min, held at 2000 ° C for 30 minutes, cooling rate of 5 ° C / mi
It was cooled to 500 ° C. by n and then allowed to cool to room temperature. After the treatment, the boron carbonitride fiber was kept wound around the form without breaking or unraveling. The stretch ratio at this time was 6.5%.

From the powder X-ray diffraction and the XPS spectra of boron and nitrogen, the obtained boron carbonitride fiber had a structure in which the C planes were laminated, and the structure had boron-carbon bonds and nitrogen. -It was confirmed that carbon bonds were present.

The orientation degree of this boron carbonitride fiber is 0.7.
4. The tensile strength was 1700 MPa.

Example 3 Boron carbonitride precursor fibers produced in the same manner as in Example 1 were wound into a loop shape having a circumference of 192 mm, and while maintaining the loop shape, a boron nitride nitride mold having a circumference of 139 mm was formed. Then, it was heat treated in a nitrogen stream as it was. The heat treatment is performed at a heating rate of 1 ° C / min up to 400 ° C, and a heating rate of 2 ° C / min at 1600 ° C from 400 ° C to 1600 ° C.
To 2000 ° C at a heating rate of 10 ° C / min, held at 2000 ° C for 30 minutes, cooling rate of 5 ° C / mi
It was cooled to 500 ° C. by n and then allowed to cool to room temperature. After the treatment, the boron carbonitride fiber was kept wound around the form without breaking or unraveling. At this time, the stretching ratio was 13.0%.

From the powder X-ray diffraction and the XPS spectra of boron and nitrogen, the obtained boron carbonitride fiber had a structure in which the C planes were laminated, and the structure had boron-carbon bonds and nitrogen. -It was confirmed that carbon bonds were present.

The orientation degree of this boron carbonitride fiber is 0.8.
2. The tensile strength was 1900 MPa.

Example 4 Boron carbonitride precursor fibers prepared in the same manner as in Example 1 were wound into a loop shape having a circumference of 192 mm, and while maintaining the loop shape, a boron nitride mold having a circumference of 143 mm was formed. Then, it was heat treated in a nitrogen stream as it was. The heat treatment is performed at a heating rate of 1 ° C / min up to 400 ° C, and a heating rate of 2 ° C / min at 1600 ° C from 400 ° C to 1600 ° C.
To 2000 ° C at a heating rate of 10 ° C / min, held at 2000 ° C for 30 minutes, cooling rate of 5 ° C / mi
It was cooled to 500 ° C. by n and then allowed to cool to room temperature. After the treatment, the boron carbonitride fiber was kept wound around the form without breaking or unraveling. At this time, the stretching ratio was 16.3%.

According to the powder X-ray diffraction and the XPS spectra of boron and nitrogen, the obtained boron carbonitride fiber has a structure in which the C plane is laminated, and the structure has a boron-carbon bond and a nitrogen-bonded structure. -The presence of a carbon bond was confirmed.

The degree of orientation of this boron carbonitride fiber is 0.8.
5. The tensile strength was 2200 MPa.

Comparative Example 1 Boron carbonitride precursor fibers produced in the same manner as in Example 1 were heat-treated in a nitrogen stream without applying tensile stress to the fibers. In the heat treatment, the temperature is increased at a rate of 1 ° C / min up to 400 ° C, 2 ° C / min from 400 ° C to 1600 ° C, and 10 ° C / min from 1600 ° C to 1800 ° C. It was held at 1800 ° C. for 30 minutes, cooled to 500 ° C. at a cooling rate of 5 ° C./min, and then allowed to cool to room temperature.

From the powder X-ray diffraction and the XPS spectra of boron and nitrogen, the obtained boron carbonitride fiber had a structure in which the C planes were laminated, and the structure had a boron-carbon bond and nitrogen. -It was confirmed that carbon bonds were present.

The orientation degree of this boron carbonitride fiber is 0.5.
5. The tensile strength was 800 MPa.

[0106] Comparative Example 2 Example 1 Similarly carbonitride boron precursor fibers produced with ^such that applying a tensile stress to the fiber Ku, was subjected to heat treatment in a nitrogen gas stream. In the heat treatment, the temperature is increased at a temperature increase rate of 1 ° C./min up to 400 ° C., the temperature increase rate of 2 ° C./min from 400 ° C. to 1600 ° C., and the temperature increase rate of 10 ° C./min from 1600 ° C. to 2000 ° C. It was held at 2000 ° C. for 30 minutes, cooled to 500 ° C. at a cooling rate of 5 ° C./min, and then allowed to cool to room temperature.

From the powder X-ray diffraction and the XPS spectra of boron and nitrogen, the obtained boron carbonitride fiber had a structure in which the C planes were laminated, and the structure had boron-carbon bonds and nitrogen. -It was confirmed that carbon bonds were present.

The orientation degree of this boron carbonitride fiber is 0.6.
6. The tensile strength was 900 MPa.

Example 5 A stirrer was placed in the middle tube of a three-necked flask having a capacity of 1 liter, and a dropping funnel containing 128 g of boron tribromide in one of the side tubes,
A ball inlet cooling pipe was attached to the remaining side pipe. A calcium chloride tube was attached to the outlet of the ball-in cooling tube. After drying the inside of the apparatus by flowing dry nitrogen at 200 ml / min for 4 hours, 300 ml of chlorobenzene and 16.4 g of acetonitrile dried over anhydrous sodium sulfate overnight were added. While stirring with a stirrer, boron tribromide was added dropwise from the dropping funnel over 2 hours. This produced a white boron tribromide-acetonitrile adduct. After dropping boron tribromide, the dropping funnel attached to the three-necked flask was removed, and 21.5 g of ammonium chloride dried at 110 ° C. overnight was added. The suspension was heated at 125 ° C. for 8 hours, filtered, washed with 100 ml of chlorobenzene, and dried under reduced pressure to obtain 48 g of a brown precipitate (yield: 80%).
I got

[0110] The carbon boron nitride precursor 15g ^D M F2
After dissolving in 00 ml, 100 ml of DMF was removed by evaporation to obtain a uniform viscous solution. 25 this solution
15kg from spinning nozzle with 60μm diameter hole at ℃
/ Cm by applying a ^second back pressure by discharging in dry air, by winding and spun continuous carbon boron nitride precursor fiber having a diameter of about 20 [mu] m. At this time, the viscosity of the spinning solution is 2.
It was 9 × 10 ⁴ poise and the spinning speed was 1.9 m / min.

The spun boron carbonitride precursor fibers were heat treated as in Example 3. The draw ratio at this time is 1
It was 2.8%.

From the powder X-ray diffraction and the XPS spectra of boron and nitrogen, the obtained boron carbonitride fiber had a structure in which the C planes were laminated, and the structure had boron-carbon bonds and nitrogen. -It was confirmed that carbon bonds were present.

The orientation degree of this boron carbonitride fiber is 0.8.
3. The tensile strength was 2000 MPa.

Example 6 A stirrer was attached to the middle tube of a three-necked flask having a capacity of 1 liter, a dropping funnel containing 16.4 g of acetonitrile was placed in one of the side tubes, and a ball-filled cooling tube was attached to the remaining side tubes. A calcium chloride tube was attached to the outlet of the ball-in cooling tube. After drying the inside of the apparatus by flowing dry nitrogen at 200 ml / min for 4 hours, 300 ml of chlorobenzene and 200 g of boron triiodide dried overnight with anhydrous sodium sulfate were added.
While stirring with a stirrer, acetonitrile was added dropwise from the dropping funnel over 2 hours. This produced a white boron triiodide-acetonitrile adduct. After the dropping of boron triiodide was completed, the cold finger directly attached to the three-necked flask was removed, and 21.5 g of ammonium chloride dried at 110 ° C. overnight was added. The suspension was heated at 125 ° C. for 8 hours, filtered, washed with 100 ml of chlorobenzene, and dried under reduced pressure to obtain 65 g of a brown precipitate (yield 79%).

20 g of this boron carbonitride precursor was added to DMF2.
After dissolving in 00 ml, 100 ml of DMF was removed by evaporation to obtain ^a uniform viscous solution. 25 this solution
15kg from spinning nozzle with 60μm diameter hole at ℃
/ Cm by applying a ^second back pressure by discharging in dry air, by winding and spun ^continuous carbon boron nitride precursor fiber having a diameter of about 20 [mu] m. At this time, the viscosity of the spinning solution is 2.
It was 8 × 10 ⁴ poise and the spinning speed was 1.9 m / min.

The spun boron carbonitride precursor fiber was heat-treated in the same manner as in Example 3. The draw ratio at this time is 1
3.1%.

From the powder X-ray diffraction and the XPS spectra of boron and nitrogen, the obtained boron carbonitride fiber had a structure in which the C planes were laminated, and the structure had boron-carbon bonds and nitrogen. -It was confirmed that carbon bonds were present.

The orientation degree of this boron carbonitride fiber was 0.8.
0 and the tensile strength was 1900 MPa.

Example 7 A stirrer was attached to the inner tube of a three-necked flask having a capacity of 1 liter, a Dewar cold finger having a cylinder containing boron trichloride was attached to one of the side tubes, and a ball-filled cooling tube was attached to the remaining side tubes. I installed each. A dewar type cold finger was attached to the ball inlet cooling tube, and a calcium chloride tube was attached to the outlet of the cold finger. After drying the inside of the apparatus by flowing dry nitrogen at 200 ml / min for 4 hours, 300 ml of chlorobenzene and 16.4 g of acetonitrile dried over anhydrous sodium sulfate overnight were added. Two
Fill one cold finger with dry ice-acetone, stir with a stirrer, and add boron trichloride 60 from the cold finger directly attached to the three-necked flask.
g was condensed and dropped over 2 hours. This produced a white boron trichloride-acetonitrile adduct. After the dropping of boron trichloride was completed, the cold finger directly attached to the three-necked flask was removed, and 27.2 g of monomethylamine hydrochloride dried at 110 ° C. overnight was added. When this suspension was heated to 125 ° C. for 8 hours, generation of hydrogen chloride almost disappeared, and a brown precipitate was formed. The product is filtered off the precipitate, chlorobenzene 100m washed with ^l, then dried under reduced pressure to carbon boron nitride precursor 25 g (yield: 80
%) Was obtained.

10 g of this boron carbonitride precursor was added to DMF2.
After dissolving in 00 ml, 100 ml of DMF was removed by evaporation to obtain a uniform viscous solution. 25 this solution
15kg from spinning nozzle with 60μm diameter hole at ℃
/ Cm by applying a ^second back pressure by discharging in dry air, by winding and spun continuous carbon boron nitride precursor fiber having a diameter of about 20 [mu] m. At this time, the spinning solution has a viscosity of 3.
It was 0 × 10 ⁴ poise and the spinning speed was 1.8 m / min.

The spun boron carbonitride precursor fiber was heat-treated in the same manner as in Example 3. The draw ratio at this time is 1
It was 3.2%.

From the powder X-ray diffraction and the XPS spectra of boron and nitrogen, the obtained boron carbonitride fiber had a structure in which the C planes were laminated, and the structure had boron-carbon bonds and nitrogen. -It was confirmed that carbon bonds were present.

The orientation degree of this boron carbonitride fiber was 0.8.
0, the tensile strength was 1800 MPa.

Example 8 A stirrer was attached to the inner tube of a three-necked flask having a volume of 1 liter, a Dewar cold finger having a cylinder containing boron trichloride was attached to one of the side tubes, and a ball-filled cooling tube was attached to the remaining side tubes. I installed each. A dewar type cold finger was attached to the ball inlet cooling tube, and a calcium chloride tube was attached to the outlet of the cold finger. After drying the inside of the apparatus by flowing dry nitrogen at 200 ml / min for 4 hours, 300 ml of chlorobenzene and 41.2 g of benzonitrile dried over anhydrous sodium sulfate overnight were added. Two
Fill one cold finger with dry ice-acetone, stir with a stirrer, and add boron trichloride 60 from the cold finger directly attached to the three-necked flask.
g was condensed and dropped over 2 hours. This produced a white boron trichloride-benzonitrile adduct. After the addition of boron trichloride was completed, the cold finger directly attached to the three-necked flask was removed, and 21.5 g of ammonium chloride dried at 110 ^{° C.} overnight was added. When this suspension was heated to 125 ° C. for 8 hours, generation of hydrogen chloride almost disappeared, and a brown precipitate was formed. The formed precipitate was separated by filtration, washed with 100 ml of chlorobenzene, and then dried under reduced pressure to obtain 27 g (yield 79%) of a boron carbonitride precursor.

10 g of this boron carbonitride precursor was added to DMF2.
After dissolving in 00 ml, 100 ml of DMF was removed by evaporation to obtain a uniform viscous solution. 25 this solution
15kg from spinning nozzle with 60μm diameter hole at ℃
/ Cm by applying a ^second back pressure by discharging in dry air, by winding and spun continuous carbon boron nitride precursor fiber having a diameter of about 20 [mu] m. At this time, the viscosity of the spinning solution is 2.
It was 9 × 10 ⁴ poise and the spinning speed was 1.8 m / min.

[0126] The ^spun carbon boron nitride precursor fiber was subjected to heat treatment in the same manner as in Example 3. The draw ratio at this time is 1
It was 3.2%.

According to powder X-ray diffraction and XPS spectra of boron and nitrogen, the obtained boron carbonitride fiber has a structure in which C-planes are laminated, and the structure has a boron-carbon bond and nitrogen. -The presence of a carbon bond was confirmed.

The degree of orientation of the boron carbonitride fiber is 0.8
2. The tensile strength was 1900 MPa.

Example 9 A stirrer was attached to the inner tube of a three-necked flask having a capacity of 1 liter, a Dewar cold finger with a cylinder containing boron trichloride was attached to one of the side tubes, and a ball-filled cooling tube was attached to the remaining side tubes. I installed each. A dewar type cold finger was attached to the ball inlet cooling tube, and a calcium chloride tube was attached to the outlet of the cold finger. After drying the inside of the apparatus by flowing dry nitrogen at 200 ml / min for 4 hours, 300 ml of chlorobenzene and 41.2 g of acrylonitrile dried overnight with anhydrous sodium sulfate were added.
Fill two cold fingers with dry ice-acetone, stir with a stirrer, and apply boron trichloride 6 from the cold finger directly attached to the three-necked flask.
0 g was condensed and dropped over 2 hours. This produced a white boron trichloride-acrylonitrile adduct.
After the dropping of boron trichloride was completed, the cold finger directly attached to the three-necked flask was removed, and 21.5 g of ammonium chloride dried at 110 ° C. overnight was added. When this suspension was heated to 125 ° C. for 8 hours, generation of hydrogen chloride almost disappeared, and a brown precipitate was formed. The formed precipitate was separated by filtration, washed with 100 ml of chlorobenzene and then dried under reduced pressure to obtain 24 g of boron carbonitride precursor (yield: 77
%) Was obtained.

10 g of this boron carbonitride precursor was added to DMF2.
After dissolving in 00 ml, 100 ml of DMF was removed by evaporation to obtain a uniform viscous solution. 25 this solution
15kg from spinning nozzle with 60μm diameter hole at ℃
/ Cm by applying a ^second back pressure by discharging in dry air, by winding and spun continuous carbon boron nitride precursor fiber having a diameter of about 20 [mu] m. At this time, the viscosity of the spinning solution is 2.
It was 9 × 10 ⁴ poise and the spinning speed was 1.9 m / min.

The spun boron carbonitride precursor fiber was heat-treated in the same manner as in Example 3. The draw ratio at this time is 1
3.1%.

From the powder X-ray diffraction and the XPS spectra of boron and nitrogen, the obtained boron carbonitride fiber had a structure in which the C planes were laminated, and the structure had a boron-carbon bond and nitrogen. -It was confirmed that carbon bonds were present.

The orientation degree of this boron carbonitride fiber was 0.8.
1. The tensile strength was 1800 MPa.

Example 10 Boron carbonitride precursor 10 prepared in the same manner as in Example 1
g and polyacrylonitrile having a weight average molecular weight of 500,000.
Dissolve 05g in DMF200ml and then add DMF100
A uniform viscous solution was obtained by evaporating off ml. This solution was discharged into dry air by applying a back pressure of 15 kg / cm ² from a spinning nozzle having a hole with a diameter of 60 μm at 25 ° C., and wound up to obtain a continuous boron carbonitride precursor having a diameter of about 20 μm The fibers were spun. At this time,
The viscosity of the spinning solution was 6 × 10 ¹ poise and the spinning speed was 19.5 m / min.

The spun boron carbonitride precursor fibers were heat treated in the same manner as in Example 3. The draw ratio at this time is 1
It was 3.2%.

From the powder X-ray diffraction and the XPS spectra of boron and nitrogen, the obtained boron carbonitride fiber had a structure in which the C planes were laminated, and the structure had boron-carbon bonds and nitrogen. -It was confirmed that carbon bonds were present.

The orientation degree of this boron carbonitride fiber was 0.8.
1. The tensile strength was 1800 MPa.

Claims (4)

[Claims] 1. A surface (C) formed by connecting a 6-membered ring formed by bonding carbon, boron and nitrogen in the plane direction of the 6-membered ring.
A boron carbonitride fiber made of boron carbonitride having a laminated structure of (faces) having a tensile strength of at least 1400 MPa. 2. A plane (C) formed by connecting a 6-membered ring formed by combining carbon, boron and nitrogen in the plane direction of the 6-membered ring.
Plane) is a boron carbonitride fiber made of boron carbonitride having a laminated structure, wherein at least a part of the C plane is oriented substantially parallel to the fiber axis of the boron carbonitride fiber. A boron carbonitride fiber having a degree of orientation of the C plane of at least 0.70. 3. (a) Boron carbonitride by reacting an adduct of boron trihalide with a nitrile compound and ammonium halide or primary amine hydrohalide in the presence of boron trihalide. Generate precursors,
(B) The boron carbonitride precursor is dissolved in a solvent to prepare a boron carbonitride precursor solution, and (c) the boron carbonitride precursor solution is spun to form a boron carbonitride precursor fiber. Formed,
(D) A method for producing a boron carbonitride fiber, which comprises heating the boron carbonitride precursor fiber at 1600 to 2300 ° C. while applying tensile stress in an inert gas atmosphere. 4. (a) Boron carbonitride by reacting an adduct of a boron trihalide with a nitrile compound and an ammonium halide or a primary amine hydrohalide in the presence of boron trihalide. Generate precursors,
(B) The boron carbonitride precursor and acrylonitrile-based polymer are dissolved in a solvent to prepare a boron carbonitride precursor solution, and (c) the boron carbonitride precursor solution is spun to form carbonitride boron. Forming a carbon precursor fiber, and (d) heating the boron carbonitride precursor fiber at 1600 to 2300 ° C. under an inert gas atmosphere while applying tensile stress. Production method.