JPS60185820A - Production of nonwoven fabric consisting of carbon fiber - Google Patents

Abstract

PURPOSE:To obtain the titled nonwoven fabric having improved electric conductivity, by spinning fiber-forming pitch, depositing the resultant filaments in the form of a sheet while drawing the filaments, joining the filaments at the entangled points between the filaments, and infusibilizing and firing the resultant sheet. CONSTITUTION:Fiber-forming pitch, e.g. petroleum based pitch, is extruded through nozzle holes into continuous liquid filaments, which are then transferred along a compressed gas stream while being drawn with the compressed gas stream, and deposited in the form of a sheet to form a nonwoven fabric. Filaments are joined at many entangled points therebetween, infusibilized in an oxidizing atmosphere and fired in an inert gas atmosphere to afford the aimed nonwoven fabric.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a method for producing a nonwoven fabric made of carbon i-fibers.

Short fibers made from carbon fibers made into a non-woven fabric using a binder have excellent electrical conductivity, chemical resistance, resin impregnation properties, etc., and have been widely used for various purposes.

However, these conventional nonwoven fabrics have the disadvantage that the adhesive strength and bonding point density at the bonding points between short fibers greatly affect the physical properties of the nonwoven fabric, and the contribution of the excellent physical properties of carbon fibers to the nonwoven fabric is extremely small. It had

The inventors of the present invention have made extensive efforts to improve the drawbacks of the prior art, and have thus arrived at the present invention.

An object of the present invention is to provide a method for producing a nonwoven fabric made of carbon fibers having excellent electrical conductivity and mechanical properties.

That is, in the method of the present invention, when bath-melt spinning fiber-forming pitch, the filaments spun from the II/J/Y nostle are drawn by a compressed gas flow and then deposited in a sheet form. It is characterized in that after joining r#8 through a large number of intertwining points, it is subjected to infusibility treatment and firing treatment.

Hereinafter, the present invention will be explained in detail. In the present invention, fiber-forming pitch is one that can form continuous filament-like fibers by spinning it in a molten state from a spinning nozzle, and a typical example thereof is coal-based pitch. and petroleum-based pitches, but there may be other pitches that have the above-mentioned properties, such as pitches produced as by-products in the petrochemical industry, or pitches obtained by dry distilling various resins. etc. can be mentioned.

The spinning nostle used in the present invention is a conventional jet spinning device fp.
Use the form used in t. That is, the fiber-forming pitch that has been RJ-plasticized in the extruder is extruded from a nozzle hole as a continuous liquid filament.

Extruded from the nozzle hole: 1. Provided along the filament and adjacent to the nozzle hole. A compressed gas flow is drawn out from the hole, and the filament is drawn by this compressed gas flow. The filaments are then carried along with the compressed gas stream and deposited on the collection surface to form a nonwoven fabric. It is important that the filaments deposited on the collecting surface knee have some degree of bonding to each other at the interlacing points due to entanglement of the filaments themselves. In order to form a sheet in which the filaments are joined to each other at the interlacing point, a temperature of 280 to 40° C. is normally obtained at a flow rate of 0.1 to 1.5 f/min/orifice and a fluid pressure of 0.5 to 4 kg/d.
50 to 250 from the nozzle hole using heated air at 0°C.
The melt blowing tip is good on the collection surface installed at position I111. In this case, it is difficult to perform melt blowing while moving the nozzle from side to side in order to eliminate the direction a of the obtained nonwoven fabric.

If there is no bonding at all, a binder may or may not be necessary to finally obtain a nonwoven fabric, and even in this case, the resulting nonwoven fabric has insufficient tenacity and mechanical properties, and the present invention is not suitable. Unable to achieve the goal.

Air is usually used as the compressed gas used in the present invention. The compressed gas temperature is generally in the same temperature range as the nozzle die temperature or even higher.

It is preferable that the collection surface on which the filaments extruded from the spinning nozzle holes are deposited has at least a portion of its bottom that is breathable, such as a net. It is also desirable that the collection surface be of a mechanism that can run continuously, such as a belt conveyor. The filaments deposited on the collecting surface are subjected to an infusible treatment and a firing treatment while still in the deposited state.

For the infusibility treatment, a method used for ordinary pitch-based carbon fibers is used. For example, air, N01RO□, 0
1 to 4 at 100 to 400°C with oxidizing gas such as
This is done by contacting the filament for a period of time.

The firing treatment applied to the present invention may be performed by the method used in the production of ordinary pitch-based carbon fibers, as in the case of the above-mentioned infusibility treatment. For example, after infusibility treatment,
500 to 1,500 in a suitable inert gas, e.g. nitrogen
It is carbonized by firing at a temperature of 0.1 to 1.5 hours. that time,
It is also possible to advance graphitization by performing the firing treatment at a temperature of 2,000° C. or higher. Furthermore, by graphitizing the material under tension at 2,000 to 2,000 °C, a product with higher strength and higher elastic modulus can be obtained.

According to the present invention, a nonwoven fabric made of pitch-based carbon fiber can be produced under industrially advantageous conditions without using a binder.

In addition, since the nonwoven fabric obtained by the present invention has a large number of joined interlacing points, it can be manufactured using a binder, and has excellent electrical conductivity and mechanical properties compared to conventional nonwoven fabrics made of short fibers, and is stampable. It can be used more efficiently as a material for sheeting, sheet molding, and electromagnetic shielding.

A more detailed explanation will be given below with reference to Examples.

Super Example 1 Average molecular i700. Solvent-refined coal with a softening point of 245° C. was filled in a vessel-type melter, melted in a heating bath to an internal temperature of 250° C. from the outside of a nitrogen gas filler, and fed into a die shown in FIG. 1 using a can pump.

From 75 0.8 mm orifices lined up in a row with 2N pitch, the discharge amount and injection pressure of 0.5 f1 min/orifice is 1.5! Hemelt blowing was carried out on a conveyor net of the manufacturing apparatus shown in FIG. 2 using heated air at an iI/clIG temperature of 85 (JC) to obtain a nonwoven fabric with a width of 900 m.

The obtained nonwoven fabric was cut into lengths of 000 m and then
It was placed in an electric furnace at 150'C in an air atmosphere, and the temperature was 0.
The temperature was raised to 280'C at a heating rate of 5°C/min and held at this temperature for 90 minutes to make it infusible.

Then, in a nitrogen atmosphere, the temperature was increased to t, o at a heating rate of 8.3°C/min.
The temperature was raised to oo°C and held for 20 minutes to perform carbonization. Table 1 shows the physical properties of the obtained nonwoven fabric.

In addition, carbon fibers with a fiber diameter of 25 μm and a fiber length of 1 m (1 m) obtained under the conventional production conditions of pitch-based carbon fiber using the solvent-refined coal used in Example 1 as a raw material were matted with an epoxy thread binder. The physical properties of the molded product are also listed in Table 1 as Comparative Example 1.

Table 1

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of one embodiment of a die head used in the melt blowing step of the present invention, and FIG. 2 is a schematic diagram of an apparatus used in the nonwoven fabric manufacturing step of the method of the present invention. ■, melt pitch channel 2, die body 8, orifice tip 4, gas channel 5, gas flow adjustment plate 6, die head 7, conveyor net 8, nonwoven fabric 9, conveyor net drive shaft〃 Kanebo Gosen Co., Ltd.

Claims (1)

[Claims] When melt-spinning fiber-forming pitch, the filaments spun from a spinning nozzle are drawn by a compressed gas flow and then conveyed and deposited in a sheet form, and the filaments are joined by a large number of intertwining points. A method for producing a nonwoven fabric made of charcoal yarn, which is characterized by carrying out an infusibility treatment and a firing treatment.