JPH03260109A - Gas phase grown carbon fiber-mixed organic fiber - Google Patents

Abstract

PURPOSE:To provide the subject fiber having high strength, high elastic modulus and low thermal shrinkability, readily and homogeneously dispersed in a matrix such as mortar and employed in FRP by compounding gas phase-grown carbon whiskers each having a length/diameter ratio within a specific range and a diameter of <= a specified valve. CONSTITUTION:The objective fiber contains 1.5-80wt.%, preferably 2-50wt.%, of gaseous phase-grown carbon whiskers each having a length/diameter ratio of 10-5000, preferably 50-3000, and a diameter of <=5mum, the whiskers being drawn preferably at least 1.15 times and being arranged toward the axis of the fiber, and has preferably a diameter of 15-500mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to organic fibers mixed with vapor-grown carbon whiskers that can be used in fiber-reinforced plastics, fiber-reinforced cement, and the like.

[Prior Art] It is already known to mix inorganic fibers into organic fibers and spin them into fibers. For example, Tokuko Sho 52-3060
No. 8 discloses that organic fibers have a length/diameter ratio of lO to 1.
000 and a diameter of 20μ or less, the fibrous inorganic material is approximately oriented in the axial direction of the organic fiber by being stretched at least twice as much. ing.

Furthermore, JP-A-52-121523 discloses that a mixture of a large number of whiskers and a molten matrix material is continuously introduced into a fine-pore nozzle to create a flow velocity gradient in the mixture near the fine-pore nozzle. of whisker-reinforced mixed fibers, comprising the steps of uniformly orienting whiskers in the molten matrix material by a method, and cooling a fibrous mixture of the molten matrix material and the whiskers that has exited the pore nozzle. A manufacturing method is disclosed.

[Problem to be solved by the invention]

By the way, when whiskers are used as reinforcing fibers in composite materials, they need to be uniformly dispersed in the matrix. However, because the whiskers have a small diameter, the fibers tend to get entangled with each other, forming fiber balls that are not uniformly dispersed, making it difficult to achieve a reinforcing effect.Furthermore, because the whiskers have a small diameter, their absolute strength (power) is low, making them difficult to handle.

(Means for Solving Problem 11) The present invention has been made to solve these problems, and the vapor-grown carbon whiskers have various excellent properties such as long fibers and excellent conductivity. It was discovered that by spinning these whiskers together with an organic polymer having fiber-forming ability, it is possible to minimize the damage to the whiskers and greatly enhance the reinforcing effect.

That is, the present invention relates to an organic fiber containing 1.5 to 80% by weight of vapor-grown carbon whiskers having a length/diameter ratio of 10 to 5000 and a diameter of 5 nm or less.

Carbon whiskers are obtained by a gas phase method, and carbon sources include methane, acetylene, benzene, toluene, etc., as well as crude light oils, which are byproducts from coke ovens, carbon oil, naphthalene, medium oil, anthracene oil, heavy oil, pitch,
Coal tar, hydrides thereof, mixtures thereof, etc. may be used.

Furthermore, those having heteroatoms can also be used, such as thiophenes, thiols and thiophenols. Catalyst sources include organic iron compounds such as ferrocene, iron acetylacetate salts, and di(indenyl)iron (IF), as well as other transition metals such as titanium, vanadium, chromium, manganese, cobalt, nickel, rubidium, rhodium, and tungsten. , palladium, and other organic compounds are used. The above carbon source gas and catalyst source gas are conveyed with a carrier gas and heated to 600-1300°C.
Carbon whiskers are formed by heating. In addition to transporting the raw material gases mentioned above, the carrier gas is also required to maintain a reducing atmosphere within the system, and hydrogen gas is used for this purpose, but the converter gas discharged from steel plants is a high-temperature reducing gas. By using this, high-quality carbon whiskers can be manufactured at low cost.

The diameter of the carbon whisker used in the present invention is 0.1
-about 5-degrees, preferably about 1-3-degrees, and the length to diameter ratio is about 10-5000, preferably 50-300
It is about 0. If the length/diameter ratio is less than 10, the reinforcing effect will be insufficient, while if the length/diameter ratio exceeds 5000, the incorporation into organic polymers will be poor and spinning will be difficult.

The carbon whisker content in organic fibers is 1.5
It is about 80% by weight, preferably about 2 to 50% by weight. If it is less than 1.5% by weight, the reinforcing effect will be insufficient, while if it exceeds 80% by weight, it will be difficult to mix into the organic polymer and spinning will be difficult.

Any organic polymer may be used as long as it has fiber-forming ability, such as polyvinyl alcohol, polyacrylonitrile,
It is appropriately selected from nylon, polypropylene, polyethylene, polyvinyl chloride, polyester, etc.

The spinning method may be a known method, such as a melt extrusion method or a wet spinning method. However, a wet method is preferable for spinning the organic fibers of the present invention, and by this method, breakage of carbon whiskers can be minimized and carbon whiskers can be easily and uniformly dispersed. The melting, concentration, etc. of the organic polymer in the wet method may be the same as in the conventional method. It is preferable to stretch the fibers after spinning, thereby improving the axial orientation and tensile strength of the carbon whiskers.

The diameter of the organic fibers obtained in this way is 15 to 500μ.
A suitable range is preferably about 30 to 300n. If the fiber diameter is less than 15Q, fiber poles are likely to form, while if it exceeds 500n, the carbon whiskers will not be oriented in the axial direction.

[Operation] By spinning carbon whiskers together with an organic polymer, we succeeded in orienting them without causing breakage.

〔Example〕

Example 1 Sufficiently purified to remove residual sodium acetate, with a degree of 99
．． Polyvinyl alcohol powder having a concentration of 6 mol % and a degree of polymerization of 1500 was added little by little at room temperature to gently stirred purified dimethyl sulfoxide to form a homogeneous dispersion solution of 20% by weight. Next, a diameter of 2n and a length of 3m (
Gas-phase Kaicho carbon whiskers with an aspect ratio of 1500) were added and mixed. The amount of vapor grown carbon whiskers added was 25% by weight based on polyvinyl alcohol. 80 after dispersing vapor grown carbon whiskers
The mixture was heated at °C for 11 hours to completely dissolve the polyvinyl alcohol and to sufficiently disperse the vapor-grown carbon whiskers.

This solution was spun into an acetone coagulation bath at 25° C. from a spinning nozzle with a pore size of 0.5 to obtain a coagulated thread. 20 pieces of this coagulated thread
A drawn yarn with a diameter of 0.15 cm was obtained by drawing on a hot plate at 0°C, and this was heat-treated at 230°C. When this heat-treated system was cut in a direction perpendicular to the fiber axis and the cut surface was observed with a scanning electron microscope, it was confirmed that the vapor-grown carbon whiskers were sufficiently oriented in the fiber axis direction of the fiber. It was also found that polyvinyl alcohol and vapor-grown carbon whiskers were in close contact with each other and had good affinity, and that the vapor-grown carbon whiskers in the fibers were not damaged in any way by mixing or stretching. The tensile strength of this fiber was 184 kg/ms'' and the elastic modulus was 10 t/an''.

The fibers were cut into lengths of 6 cm and dry-kneaded with ordinary Polytoland cement and Shirasu balloons. When the fibers were cut into lengths of 6 cm, they were uniformly dispersed without forming fiber balls. Moreover, no damage to the threads was observed.

Water-cement ratio = 0.62, aggregate-cement ratio = 0.24,
A lightweight mortar was made by adjusting the amount of fiber mixed to 2.0vo1%. The curing method was as follows: After molding, the mortar was allowed to stand in a curing chamber at 20°C and 65% RH, and then cured in water at 25°C for 6 days.The bending strength of one piece of mortar was 131 kg/cj.

Example 2 Sufficiently purified to remove residual sodium acetate, with a degree of 99
．． A homogeneous dispersion solution of 5% by weight polyvinyl alcohol powder with a polymerization degree of 1750 was prepared by dispersing and dissolving polyvinyl alcohol powder with a degree of polymerization of 1750 in gently stirred purified dimethyl sulfoxide at room temperature. Next, vapor grown carbon whiskers having a diameter of 2n and a length of 3mm (aspect ratio 1500) were added and mixed. The amount of vapor grown carbon whiskers added was 15% by weight based on polyvinyl alcohol. After dispersing the vapor-grown carbon whiskers, the mixture was heated at 80° C. for 11 hours to completely dissolve the polyvinyl alcohol and to sufficiently disperse the vapor-grown carbon whiskers.

This solution was heated at 20'C from a spinning nozzle with a pore size of 0.2 wa.
A coagulated thread was obtained by spinning in a methanol coagulation bath. This coagulated thread was drawn on a hot plate at 200°C and further heat treated at 240'C to obtain a drawing heat-treated system with a diameter of 0.08 mm. When this stretched heat-treated system was cut in a direction perpendicular to the fiber axis and the cut surface was observed using a scanning electron microscope, it was confirmed that the vapor-grown carbon whiskers were sufficiently oriented in the direction of the fiber axis. . It was also found that polyvinyl alcohol and vapor-grown carbon whiskers were in close contact with each other and had good affinity, and that the vapor-grown carbon whiskers in the fibers were not damaged in any way by mixing or stretching.

The tensile strength of this fiber is 153 kg/+n'' and the elastic modulus is 9.
．． It was 5t/2 ton. When this fiber was cut into lengths of 6 wa and dry kneaded with mortar, it was uniformly dispersed without forming fiber balls. Moreover, no damage to the threads was observed.

Example 3 Sufficiently purified to remove residual sodium acetate, with a degree of 99
．． A homogeneous dispersion solution of 25% by weight was prepared by dispersing and dissolving polyvinyl alcohol powder of 0 mol % and degree of polymerization of 1000 in gently stirred purified dimethyl sulfoxide at room temperature. 1 m (aspect ratio 500) of vapor grown carbon whiskers was added and mixed. The amount of vapor grown carbon whiskers added was 78% by weight based on polyvinyl alcohol. After the vapor-grown carbon whiskers were dispersed, the mixture was heated at 80° C. for 1 hour to completely dissolve the polyvinyl alcohol and to sufficiently disperse the vapor-grown carbon whiskers.

This solution was spun into a methanol coagulation bath at 20° C. from a spinning nozzle with a hole diameter of 0.65 m to obtain a coagulated thread. This coagulated thread was drawn on a hot plate at 200°C and heat treated on a hot plate at 235°C to obtain a drawing heat treatment system with a diameter of 0.18 mm. When this drawing heat-treated system was cut in a direction perpendicular to the fiber axis and the cut surface was observed using a scanning electron microscope, it was confirmed that the vapor-grown crab whiskers were well oriented in the fiber axis direction of this fiber. Ta. It was also found that polyvinyl alcohol and vapor-grown carbon whiskers were in close contact with each other and had good affinity, and that the vapor-grown carbon whiskers in the fibers were not damaged in any way by mixing or stretching.

The tensile strength of this fiber is 187 kg/am” and the elastic modulus is 2.
It was 8t/-■1. When this fiber was cut into lengths of 6 m and dry kneaded with mortar, it was uniformly dispersed without forming fiber balls. Moreover, no damage to the threads was observed.

Example 4 Sufficiently purified to remove residual sodium acetate, with a degree of 99
．． A homogeneous dispersion solution of 20.2% by weight was prepared by dispersing and dissolving polyvinyl alcohol powder of 0 mol % and a degree of polymerization of 1750 in gently stirred purified dimethyl sulfoxide at room temperature. Next, vapor-grown carbon whiskers having a diameter of 1.5n1 and a length of 1- (aspect ratio 670) were added and mixed. The amount of vapor grown carbon whiskers added was 58% by weight based on the polyvinyl alcohol. After dispersing the vapor grown carbon whiskers at 80°C, 1
The mixture was heated for a period of time to completely dissolve the polyvinyl alcohol and to sufficiently disperse the vapor-grown carbon whiskers.

This solution was passed through a spinning nozzle with a hole diameter of 0.15 mm at 20°C.
The coagulated thread was spun and coagulated in a coagulation bath using an aqueous solution of sodium sulfate as a coagulation bath, and the coagulated thread was subjected to a multi-stage coagulation and stretching heat treatment following coagulation to obtain a stretching heat treatment system having a diameter of 0.09 am. When this fiber was cut in a direction perpendicular to the fiber axis and the cut surface was observed with a scanning electron microscope, it was confirmed that the vapor-grown carbon whiskers were sufficiently oriented in the fiber axis direction of the fiber. It was also found that polyvinyl alcohol and vapor-grown carbon whiskers were in close contact with each other and had good affinity, and that the vapor-grown carbon whiskers in the fibers were not damaged in any way by mixing or stretching.

The tensile strength of this fiber is 177 kg/mm” and the elastic modulus is 1.
It was 7t/llm2. When this fiber was cut into lengths of 6 mm and dry kneaded with mortar, it was uniformly dispersed without forming fiber balls. Moreover, no damage to the threads was observed.

Example 5 A copolymer of 95.7 mol% acrylonitrile, 4 mol% methyl acrylate, and 0.3 mol% sodium styrene sulfonate was obtained by solution polymerization using dimethyl sulfoxide as a solvent and azobisisobutyronitrile as a polymerization initiator. . The degree of polymerization of the copolymer is 37,000, and the solution concentration is 25% by weight.
Met. Vapor-grown carbon whiskers having a diameter of 2 μm and a length of 3 μm (aspect ratio 1500) were added to this solution and mixed. The amount of vapor grown carbon whiskers added was 35% by weight based on the acrylic copolymer. The mixing and dispersion of vapor-grown carbon whiskers was uniform. This solution was used as a spinning dope and spinning was carried out using a spinning nozzle with a pore size of 0.1 iW in a dimethyl sulfoxide/water based spinning bath by a multi-stage coagulation and stretching method to obtain a drawn yarn. This drawn yarn was dried at 130° C. and densified. When this fiber was cut in a direction perpendicular to the fiber axis and the cut surface was observed with a scanning electron microscope, it was confirmed that the vapor-grown carbon whiskers were sufficiently oriented in the fiber axis direction of the fiber. It was also found that the acrylic copolymer and vapor-grown carbon whiskers were in close contact and had good affinity, and that the vapor-grown carbon whiskers in the fibers were not damaged in any way by mixing or stretching. . The tensile strength of this fiber was 80) cg/mm'' and the elastic modulus was 7.5 t/arm''. When this fiber was cut into 6 lengths and dry kneaded with mortar, it was uniformly dispersed without forming fiber balls. Moreover, no damage to the threads was observed.

A lightweight mortar (vf=1.5%) was made in the same manner as in Example 1, and its bending strength was examined and found to be 90 kg/cif.

〔Effect of the invention〕

The fibers of the present invention have less breakage of carbon whiskers, good orientation of carbon whiskers, high strength, high elasticity, and low heat shrinkage. Moreover, it can be easily and uniformly dispersed in a matrix such as mortar.

Claims (2)

[Claims] (1) The length/diameter ratio is 10 to 5000 and the diameter is 5
Vapor-grown carbon whiskers with a diameter of 1.5 μm or less
Organic fiber containing 80% by weight (2) the organic fiber is stretched at least 1.15 times or more;
(3) The organic fiber according to claim (1), wherein the whiskers are oriented in the axial direction of the fiber. (3) The organic fiber according to claim (1), wherein the organic fiber has a diameter of 15 to 500 μm.