JPS6232179A - Preparation of raw material pitch for carbonaceous material - Google Patents

Abstract

PURPOSE:To prepare pitch consisting substantially of an optically anisotropic phase and having an excellent spinning property, by heat-treating petroleum-base heavy oil and removing a formed meso phase as bulk meso phase, followed by a 2nd-step heat treatment. CONSTITUTION:Petroleum-based heavy oil is subjected to a 1st-step heat treatment and a formed meso phase is removed as bulk meso phase to produce an optically isotroptic pitch. The pitch is subjected to a 2nd heat treatment in a vacuum to obtain a pitch in which an optically anisotropic phase substantially accounts for 100%. The 1st-step heat treatment should pref. be performed at 430-480 deg.C under a normal pressure or under a pressure for 0.5-3hr. under stirring. Removal of the bulk meso phase is done by agitating the heat-treated product in an inert gas atmosphere at about 200-300 deg.C for less than 60min so that the bulk meso phase may be removed as aggregate. The 2nd-step heat treatment should pref. be performed in an inert gas atmosphere, at 380-420 deg.C under a pressure of 1-5mm Hg for 2-5hr.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to carbon materials, and particularly to a method for determining pitch for carbon materials with excellent spinnability.

[Background of the invention]

In recent years, from the perspective of effective use of fossil fuel resources, research on carbon material manufacturing technology that uses petroleum-based or coal-based heavy oil as a raw material for various carbon materials has been advanced from various directions.

Incidentally, although carbon materials are generally light in weight and have excellent heat resistance, corrosion resistance, electrical conductivity, etc., there is a problem in that they are not always fully satisfactory in terms of mechanical properties, particularly tensile strength and elastic modulus.

On the other hand, among carbon materials, carbon fibers are required to have excellent spinnability as a raw material for producing these carbon materials, and therefore have unique characteristics that are different from other carbon materials mainly composed of molded bodies. For example, when producing carbon mH from heavy oil-based raw material pitch, the raw material pitch must have excellent spinnability, and the carbon fibers produced must have excellent elastic modulus and strength.

From this point of view, various methods for producing carbon fiber using heavy oil-based pitch as a spinning raw material have been proposed (for example, Japanese Patent Publication No. 1987-376, Japanese Patent Publication E ¥159).
-3567, etc.), conventionally known raw material bits for carbon materials are not necessarily satisfactory in terms of spinnability, and the mechanical properties of carbon materials obtained from these raw material bits are still not sufficiently excellent. do not have.

[Summary of the invention]

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a method for producing a raw material pitch for carbon materials that has excellent spinnability and has substantially 100% of the optically anisotropic portion. do.

As a result of intensive research into a method for obtaining raw material pitch for carbon materials that requires excellent spinnability, such as carbon fiber, the inventors of the present invention have found that, in a two-step heat treatment, After removing the mesophase as a bulk mesophase, a secondary heat treatment simultaneously removes early-formed polycondensates that inhibit spinnability and solids such as ash and catalyst contained in the raw materials. It has been found that it is possible to obtain a raw material pitch for carbon materials that is low, homogeneous, has excellent spinnability, and has substantially 100% optical anisotropy.

The method for producing raw material pitch for carbon materials of the present invention has been developed based on the above findings. In other words, the mesophase produced by primary heat treatment of petroleum-based heavy oil is removed as a bulk mesophase to form an optically isotropic bit, and then a secondary heat treatment is performed under reduced pressure to make it substantially optically anisotropic. The feature is that the part is 100% bitch 1!7.

[Detailed description of the invention]

Hereinafter, the present invention will be explained in more detail.

The raw material oils used in the method of the present invention include FCC decant oil, cracked heavy gas oil obtained by thermal decomposition of heavy residues, and those obtained by hydrogenation. A heavy oil with a boiling point of 400°C or higher is used by removing light components from fish oil.

In addition, it is preferable to remove solid contents such as residual catalyst and ash from these raw material heavy oils by melt-filtering them before entering the heat treatment step in order to homogenize the material.

The primary heat treatment of the above raw material oil is carried out at a temperature of 400 to 500°C, preferably 430 to 480''C, for 0.5 to 10 hours, preferably 0.5 to 3 hours, with stirring, and the pressure condition is normal pressure. , or under pressure.

Further, this slight heat treatment can be performed in an atmosphere of an inert gas such as nitrogen gas.

The heat-treated product obtained by the above-mentioned mild heat treatment contains early-formed polycondensates with a long softening point that adversely affects spinnability, and solid contents such as ash and catalysts that inhibit spinnability that could not be removed by the melt filtration. - The mesophases produced by the mild thermal treatment are removed together with these components in the form of bulk mesophases.

The bulk mesophase is removed by stirring the slightly heat-treated product in an inert gas atmosphere at a temperature of 200 to 300°C, preferably 260 to 300°C, for less than 60 minutes to remove the bulk mesophase. The content of mesophase is preferably 1 to 10% by weight, more preferably 2 to 7% by weight, based on the weight of the starting raw material oil of the raw material heavy oil.

In this way, a homogeneous optically isotropic pitch with bulk mesophase removed is obtained.

Next, the optically isotropic pitch obtained above is subjected to a secondary heat treatment under reduced pressure to obtain a pitch in which the optically anisotropic portion is substantially 100%.

That is, the optically isotropic pitch is set to 10 mm and 11 g or less, preferably 1 to 5 tara, in an inert gas atmosphere.
Heat treatment is carried out at a temperature of 350 to 450°C, preferably 380 to 420°C, under reduced pressure of tlg. The time for the heat treatment is 1 to 10 hours, preferably 2 to 5 hours, and stirring may be performed as necessary during the heat treatment.

Heat treatment under reduced pressure removes low molecular weight decomposition fractions and polymerization by-products that inhibit the formation of optically anisotropic moieties, and also enables processing at moderate temperatures. This is useful for quickly producing a homogeneous (narrow molecular weight distribution) optically anisotropic part while suppressing the production of condensates.

The properties of the raw material pitch for carbon materials of the present invention obtained in this way are such that the softening point is 240 to 310°C, the optical anisotropy portion is substantially 100%, and the spinnability is one level better. .

151 raw material pitch for carbon materials is spun, infusible, and carbonized (graphitized if necessary) using conventionally known methods to produce carbon with excellent strength and elastic modulus! 1I
lt is obtained.

Further, the raw material pitch for carbon materials obtained by the method 'c1:t of the present invention can be widely used as a raw material for carbon fibers, as well as a filler for carbon films, other carbon materials, and various composite materials.

(Examples of the Invention) The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 'Boiling point 400 obtained by distilling FCC decant oil under reduced pressure
The heavy fraction above 10°C was melt-filtered through a 0.6 μm filter at 80 to 100°C to remove catalysts and the like to obtain raw material heavy oil. The properties of this raw material heavy oil are shown in Table 1 below.

Next, this raw material heavy oil was stirred (5 Qr.
, p, m) L/ under normal pressure, reaction temperature 4
Thermal reforming reaction was carried out under conditions of 50° C. reaction time of 42 minutes.

Then, stir at 280°C for 60 minutes (50r, I), ff
l), and the aggregated primary bulk mesophase was
．． After removing 8wt% (relative to decant oil), the optical isotropic pitch is 19. The properties of this optically isotropic pitch are shown in Table 2 below.

This optically isotropic pitch was then heated under a nitrogen atmosphere at a pressure of 5
1,111 g was heat-treated at a reaction temperature of 390° C. for 5 hours to obtain raw material pitch for carbon material having substantially 100% optical anisotropy. The properties of the raw material pitch for carbon materials are shown in Table 2, and the quinoline dissolved content is as low as 5% by weight or less, and the optically anisotropic portion is also 100%.

When this pitch was melt-spun at a spinning temperature of 360°C using a spinning nozzle with a hole diameter of 0.3#lφ, the winding speed was 40°C.
At 07 FL/sin, it was possible to spin fibers with a diameter of 10 μm without any yarn breakage occurring once in 8 minutes.

This material was made infusible at 270° C. for 30 minutes in an air atmosphere, and then carbonized at 1000° C. for 60 minutes in a nitrogen atmosphere.

The carbon fiber thus obtained has a tensile strength of 210Kff.
/i, and the elastic modulus was 20 tons/IIrIA.

Example 2 A heavy fraction with a boiling point of 400°C or higher was prepared by distilling FCC decant oil subjected to catalytic hydrogenation according to a conventional method under reduced pressure, and this was further melt-filtered to remove catalysts and the like to reduce the weight of the raw material. I was tired of quality oil. The properties of this raw material heavy oil are as follows:
Not shown in the table.

Next, a thermal reforming reaction was carried out at a reaction temperature of 450° C. and a reaction time of 2 hours under normal pressure while stirring (50 r, p, e) in a nitrogen stream.

Thereafter, under the same conditions as in Example 1, the -order bulk mesophase was removed to obtain an optically isotropic pitch. This was heat-treated in a nitrogen atmosphere at a pressure of 2 mmHg and a reaction temperature of 400° C. for 3 hours to obtain 1q of UAf>l bits for carbon material having substantially 100% optical anisotropy. The properties of the raw material pitch for carbon materials are shown in Table 2 below.The quinoline soluble content is low at 12% by weight or less, and the optical anisotropy is 100%.

When this pitch was melt-spun using a spinning nozzle with a hole diameter of 0.3 #lφ at a spinning temperature of 3760°C, the winding speed was 38.
At 0m/min, the thread does not break even once in 10 minutes.
It was possible to spin fibers with a diameter of 8μ.

This taM was subjected to infusibility and carbonization treatment under the same conditions as in Example 1. Carbon fired at 1000℃! lvL has a tensile strength of 240PC! I/aj, tensile modulus 20 ton/
-It was.

(2)-JLJi Using the same raw material heavy oil as in Example 1, heat treatment was performed in a nitrogen atmosphere at a pressure of 11 IllI 111 g and a reaction temperature of 390° C. for 8 hours to obtain a raw material pitch for carbon material so as to obtain a similar softening point. The properties are shown in Table 2. 1-0 This pitch was melt-spun under the same conditions as in Example 1, but I
The I miscellaneous diameter was as thick as 13μ, and there were many thread breakages.

This pitch! 1lIlf was subjected to infusible carbonization treatment under the same conditions as in Example 1. The tensile strength of the carbon fiber fired at 1000°C was 16ON9/-.

Claims (1)

[Claims] The mesophase produced by primary heat treatment of petroleum-based heavy oil is removed as a bulk mesophase to obtain optically isotropic pitch, and then a secondary heat treatment is performed under reduced pressure to obtain substantially optically anisotropic pitch. A method for producing raw material pitch for carbon materials, characterized in that a pitch of 100% is obtained.