JPH01282322A - Calcination of pitch fiber - Google Patents

Abstract

PURPOSE:To prevent yarn breakage caused by sticking of the yarn to rollers by using rollers with the surface roughness higher than a specified value as the rollers in forcing the pitch yarn to run using the rollers for infusibilization and carbonization thereof. CONSTITUTION:In case a pitch yarn such as coal-based, petroleum-based or synthesized pitch is forced to run by rollers for infusibilization or carbonization thereof, the surface roughness of the rollers is made >=1S, preferably >=3S. In addition, the diameter of the respective rollers is preferably >=100mm.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for firing pitch fibers.

[Prior art] The technology for obtaining carbon fiber from pitch is, for example, disclosed in Japanese Patent Publication No. 43
-4550, JP-A No. 49-19127, etc., are well known.

Pitch yarn is fragile, and pitch yarn cannot be drawn like polymers, so it needs to be spun to a low fineness of 5 to 15μ, so it has extremely low strength and elongation, and is brittle. Therefore, the handling property is poor, surface defects are easily generated during handling, etc., which causes a decrease in productivity and a decrease in carbon fiber strength and elongation characteristics after firing.

In general, pitch yarn needs to be infusible before firing,
Like the pitch yarn, the infusible yarn is extremely fragile and has poor handling properties.

In addition, there are light valves, tar, dust, etc. that adhere to the surface of the pitch yarn during spinning, and especially when a binding material is used, the chemical and physical effects of these substances may cause the roller,
The problem is that the thread sticks to the guides very easily.

In other words, since pitch yarn has the drawback of poor handling, conditions as mild as possible are adopted for all aspects such as the yarn speed during infusibility treatment, the manner in which the yarn is handled, and the treatment time with an upper limit on the heating rate. I see the need. In other words, these problems have a major disadvantage in that they reduce productivity, economic efficiency, carbon fiber physical properties, etc. Furthermore, when obtaining carbon fibers with high viscosity and high elastic modulus using optically anisotropic pitch, defects occurring during handling and infusibility are a major cause of deterioration of physical properties.

[Problem to be Solved by the Invention 1] An object of the present invention is to provide a technology that improves the handling properties of pitch yarn and its infusible yarn, and prevents deterioration of physical properties and productivity due to yarn breakage.

[Means for Solving the Problems] The present invention is a method for firing pitch fibers in which the surface roughness of the roll is set to 1S or more when the pitch yarn is run on a roll to be infusible or carbonized.

The present invention provides a method in which the yarn sticks to the roll surface and does not break when running a bitty yarn or an infusible yarn thereof on a roll.

In this case, the surface roughness of the roll is important, and the closer the surface roughness is to a mirror surface, the more easily the yarn will stick to the roll surface, which is not preferable. If the surface roughness of the roll is less than 1S, thread breakage occurs frequently. More preferably it is 38 or more.

In particular, the entrance and exit of the infusibility furnace and carbonization furnace, the intermediate folding rolls, etc. are heated and reach high temperatures, so the effects of the present invention are high and are therefore preferable.

When pitch yarn is run on a roll, if the yarn breakage is slight, a small number of single yarns may become fluff that is cut, and gold thread breakage may not occur, but even in this case, the handling properties and physical properties of the yarn may This is not preferable from an aspect of the invention, and the effects of the present invention are particularly noticeable when high strength and high modulus of elasticity are desired.

Furthermore, the stickiness of the yarn and the resulting yarn breakage are more likely to occur as the curvature of the roll is smaller.
It is preferably used when it is 100ml or more, and more preferably used when it is 100m1l1 or more.

In addition, pitch yarns and infusible yarns are run with water, oil, etc. applied as treatment agents, and the presence of these treatment agents increases tackiness, so the effects of the present invention are more pronounced.

In particular, when polyether, wax, alcohol, dimethylpolysiloxane, phenyl-modified silicone, amine-modified silicone, etc. are used as the processing agent, the adhesiveness is high, so the effect of the present invention is high.

Pitch components are synthetic pitches made from coal-based, petroleum-based, and naphthalene-vinyl chloride, including isotropic pitch, optically anisotropic pitch, mixtures of these pitches, and pitches containing additives such as polymer compounds. means.

The optically anisotropic pitch can be within a range that provides orientation of the liquid crystal component during spinning. The amount of the optically anisotropic component is preferably 60% or more, more preferably 80% or more, from the viewpoint of the physical properties and spinning properties of the carbon fiber obtained.

As a pitch spinning method, melt spinning is usually used, but depending on the purpose, dry spinning, wet spinning, dry-wetting spinning, and other spinning methods can also be used.

For melt spinning the pitch, ordinary pressure extrusion, centrifugal spinning, flash spinning, etc. can be employed.

In addition, the method of taking the pitch and gathering the yarn is to take it with rollers, air suckers, etc., wind it up, and stack it on a tray or net, as long as it does not apply a load that may cause breakage to the fragile yarn. Ordinary methods such as

The infusibility treatment is carried out, for example, in the presence of oxygen, usually in air.
A method of oxidizing at 50 to 420'C can be applied. It is also possible to use oxidizing gases such as ozone, nitrogen oxide, and sulfur oxide as oxygen, or to use oxidizing liquids such as nitric acid, hydrogen peroxide, and potassium permanganate. Physical means such as electron beam crosslinking may also be used.

Carbonization treatment includes heating to 800 to 1700'C in an inert gas atmosphere or vacuum, and graphitization treatment includes, for example, heating at 800 to 1700'C in an inert gas atmosphere.
There is a method of heat treatment at 00'C or higher.

[Examples] Example 1 Hydrogen gas was blown into coal tar in the presence of a nickel-molybdenum catalyst, and the mixture was reacted at 400'C for 120 minutes. The obtained hydrogenated tar was passed through a 1μ filter to remove solid matter, and then heated at 350'C to obtain hydrogenated pitch. Then, it was heat-treated at 520'C and 117 mmHg for 7 minutes to reduce the mesophase pitch to 1q.

The obtained mesophase pitch has a softening point of 235°C1QI
33%, BI 39%, and anisotropy 85%.

jq pitch pitch, 3 using vent extroug
After melting at 05°C, 160C16O+; , a pitch yarn with a diameter of 10 μm was obtained.

The obtained pitch yarn was infusible while being continuously passed through an infusibility furnace at 25 Cm/min, and then carbonized in a carbonization furnace. A pair of Nelson feed rolls is installed at the inlet of each processing furnace.

Table 1 shows a comparison between the roll surface condition and the running condition of the yarn.

Table 1 [Effects of the Invention] According to the present invention, by increasing the surface roughness of the roll on which the pitch yarn and the infusible yarn run, yarn breakage due to adhesion of the yarn to the roll can be avoided.

Claims (1)

[Claims] (1) A method for firing pitch fibers, which comprises making the surface roughness of the rolls 1S or higher when infusible or carbonizing the pitch yarns by running them on rolls.