JPS60128276A - Production of binder pitch for electrode - Google Patents

Abstract

PURPOSE:To obtain inexpensively a binder pitch for an electrode with a simple operation by mixing aliphat. hydrocarbon and alicyclic hydrocarbon with specific hydrocarbon and mixing tar oil with the lower layer obtd. by stratification sepn. then removing the solvent. CONSTITUTION:1pt.wt. a hydrocarbon material contg. the condensed cyclic aromatic compd. from which the fractions up to 290 deg.C have been removed, is mixed with 1-10pts.wt. solvent consisting of aliphat. hydrocarbon and alicyclic hydrocarbon having 65-290 deg.Cb.p. or 95vol% distillation temp. The mixture is allowed to stand still to cause stratification sepn. The lower layer is distilled as it is or after tar oil is cut back, the layer is distilled to remove the whole of the solvent and a part of the arom. hydrocarbon material. The binder pitch for electrolysis is directly obtd. by the above-mentioned method without performing a heat treatment, etc. for reforming.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention produces a binder pitch for electrodes from coal-based tar pitch from which fractions with a boiling point of -20°C or lower have been removed, or a hydrocarbon substance containing a similar condensed cyclic aromatic group. It is about the method.

The properties of the binder pitch for electrodes vary depending on the type of electrode, etc., but it is generally known that it needs to have the following characteristic values.

Softening point (mercury method) 7s to 23℃ Benzene insoluble content 2 to 1 μθ polyquinoline soluble content 5 to 20% Fixed carbon 53% or more Pitch produced by ordinary continuous tar distillation generally cannot satisfy the above characteristic values. Further modification operations are required. Known methods for this modification include (1) a simple heating method, (2) a heating method by blowing air or inert gas, and (3) a heating method with the addition of a condensing agent.

However, these reforming operations are usually carried out at 0 to 20° C. for a long period of time, which requires a large amount of energy and time.

Therefore, the present inventors have conducted repeated studies on a method for manufacturing binder pitch for electrodes without carrying out the modification operation by heat treatment that is normally performed. The present invention was achieved by discovering that a pitch having characteristics as a binder pitch for stain electrodes can be obtained by adjusting the softening point of an unused and inexpensive material as necessary.

That is, the gist of the present invention is to combine a hydrocarbon substance containing a coal-based tar pinch or (and) a condensed cyclic aromatic group I compound similar thereto from which a fraction up to a boiling point of 0° C. has been removed; ! Capacity: Distillation temperature is 6J-Kota O℃
An aliphatic hydrocarbon substance and/or a solvent such as an alicyclic hydrocarbon substance are mixed in a ratio of -70 parts by weight of the solvent to 1 part by weight of the hydrocarbon substance, and then the mixture The lower layer is directly distilled, or the lower layer is mixed with a tar-based oil having a boiling point of 220° C. or higher, and then distilled to remove the solvent. A method for producing a binder pitch for electrodes, characterized in that the pitch is obtained as a bottom fraction.

The present invention will be explained in detail below.

The hydrocarbon substance used as a starting material in the present invention is typically a column bottom product obtained by distilling coal-based tar at atmospheric pressure to remove a low-boiling fraction with a boiling point of at least 2 to 0°C. Although the present invention is not limited to this, the present invention is not limited to coal-based tar pitch, which is also referred to as rhodotar. Hydrocarbons containing aromatic compounds? Among them, road tar is the most preferred.

Note that the above-mentioned hydrocarbon substance is obtained by removing at least a fraction having a boiling point of 2 to 0°C, but depending on the case, it may have a structure in which components with a higher boiling point are also removed. When removing such high boiling point components, the boiling point is usually 4! ! The limit is considered to be to exclude fractions up to θ°C, more preferably fractions up to boiling point≠00°C.

Hereinafter, the case where rhodotar is used as a starting material will be explained.

As a solvent, boiling point or ri! An aliphatic hydrocarbon substance and/or an alicyclic hydrocarbon substance having a distillation temperature of 6 to 0°C, preferably 0 to 230°C, is used.

These aliphatic hydrocarbon substances include 06-C such as hexane, heptane, octane, decane, and heptadecane.
17 paraffins and mixtures thereof, naphtha kerosene, etc.

Examples of alicyclic hydrocarbon substances include 1 of 06 to 070, such as cyclohexane, methylcycloheptane, ethylcyclohexane, cycloheptane, methylcycloheptane, ethylcyclohebutane, cyclooctane, and decalin.
13] formula hydrocarbons, alicyclic hydrocarbons having an alkyl group, and mixtures thereof, naphtha or kerosene is preferably used from the viewpoint of economy and operability.

These solvents should be selected so that the initial distillation temperature of the hydrocarbon substance and the dry point (upper limit of the boiling point range) of the solvent are several degrees Celsius or more lower, depending on the type S of the hydrocarbon substance used as the starting material. is preferred. This selection condition is especially important when the recovered solvent is recycled. If the recovered solvent contains a part of the hydrocarbon substance used as the starting material, the recovered solvent may be further purified by distillation and recycled. It is also possible to use a mixture of two or more of these solvents.

If the amount of solvent used is too small, it will be difficult to perform stratified separation in the next step 9, and if too large is used, the cost of recovering the solvent from the stratified separation liquid will be high, which is not economical. Usually, 7 to 70 parts by weight, preferably 2 to 6 parts by weight of #'i, are used based on lJi parts of the hydrocarbon substance used as a starting material.

The starting hydrocarbon substance and the solvent are mixed using a stirred tank axial flow mixer, biaxial flow nozzle, ejector, etc. at room temperature to
It is carried out at a temperature of 200° C. for a period of several seconds to one hour. The resulting mixture is heated to a temperature at which the upper layer separated by stratification from the mixture can be separated while maintaining a liquid state, for example, from room temperature to 200°C for several seconds.
Leave to stand under normal pressure or increased pressure for 1 hour. Then, the solvent is stratified into an upper layer containing the aromatic hydrocarbon substance with a reduced amount of benzene-insoluble matter and a lower layer where the benzene-insoluble matter is concentrated.

The above-mentioned mixture is allowed to stand still and separated using a container equipped with a heating jacket, a container, or the like.

The solvent fraction is removed from the obtained upper layer by distillation under normal pressure or reduced pressure, or steam distillation using an evaporator or a distillation column. The distilled off solvent fraction is recycled as a solvent as it is or after being purified.

In this distillation, the product obtained as a bottom fraction or bottom fraction varies depending on the type of hydrocarbon substance used as a starting material, but it is usually pitch-like with a boiling point of about 0. It is effectively used as a raw material for decomposed carbon materials, raw material oil for carbon black, etc.

On the other hand, the lower layer is obtained as a pitch-like material with very high viscosity. This lower layer substance can be distilled as it is, or the bottom fraction obtained by removing the solvent from the upper layer substance, or a boiling point of 26θ℃
Appropriate amounts of the above tar-based oils are cut into a cut bank, mixed, and distilled using an evaporator or distillation column under normal pressure or reduced pressure, or steam distillation to remove all of the solvent and the softening point of the resulting pitch. For adjustment, a part of the aromatic hydrocarbon is distilled off to obtain a binder pitch for electrodes.

The cantback of tar-based oil to the stratified and separated lower layer material is determined by the pinch softening point and other physical property values (
It also serves to increase the fluidity of the underlying material because it is added so that the benzene-insoluble matter, quinoline-soluble matter, etc., becomes a well-balanced binder pitch for the electrode.

TFC, when distilling off the entire amount of solvent and part of the aromatic compound, by controlling the softening point as a guide, it is possible to obtain a binder pitch for electrodes with other physical properties that are well-balanced. has been confirmed by many experimental results.

Depending on the type of raw material, solvent, and extraction conditions, it is possible to directly distill the tar-based oil into the lower layer after stratified separation without cutting it back, and distill off the entire amount of solvent and a portion of the aromatic hydrocarbon substances. Although it is possible to obtain a binder pitch for poles, the softening point generally tends to be too high compared to other physical properties. Therefore, as mentioned above, usually
The softening point is adjusted by cutting back the tar-based oil to the lower layer material and then distilling off the entire amount of the solvent and a portion of the aromatic hydrocarbon substance using a distillation column or the like.

In addition, without cutting back the tar-based oil to the lower layer material after stratified separation, the entire amount of the solvent and a part of the aromatic hydrocarbons are distilled off, and the tar-based oil is cut back to the resulting pitch to form the electrode. It is also possible to obtain pitches for But at that time,
The cutback oil preferably has a boiling point of 300°C or higher.

The recovered solvent fraction is recycled as a solvent as is in the case of the upper layer, or if the recovered solvent contains aromatic hydrocarbon substances, it is further purified using a distillation column etc. and the solvent is recovered. and used in circulation. Among the aromatic hydrocarbon substances, for the fraction with a boiling point of 20°C or higher,
It can also be used as a cutback oil to underlying materials.

As detailed above, in the present invention, a hydrocarbon substance containing a road tar or similar condensed cyclic aromatic compound from which at least the fraction below 220°C of coal tar has been removed is mixed with a specific solvent, The stratified lower layer is distilled to its reeds, or the tar-based oil is cut banked and then distilled to remove the entire amount of solvent and part of the aromatic hydrocarbon substances. This is an extremely useful method that can directly obtain a binder pinch for electrodes without the need for operations such as heat treatment for modification.

Next, the method of the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 and! Coal tar obtained by carbonization of coal is sent to an atmospheric distillation column! The oil was continuously supplied at a rate of 0.00 kg/Hr, and fractions having a boiling point of 0.degree. C. such as light oil, carbon oil, and naphthalene oil were distilled off. The fraction (road tar) distilled from the bottom of the tower is Hiro 0014.
/Hr.

Next, this road tar and a boiling point range of 160~. 260
℃ kerosene ♂ook? /Hr was introduced into a jacketed stirring tank and mixed for 30 minutes while maintaining the temperature at 73θ°C.

The resulting mixture was introduced into a jacketed standing tank maintained at 130° C., and allowed to stand for 1J' minutes to obtain a stratified and separated lower layer at a rate of 100 vol/Hr.

In addition, the initial boiling point, 260℃ or less, Tata volume %l distillation point 7
is 4t, zoc tar-based Cantvac oil, 20
was added to the solution at a ratio of 9/Hr and introduced into a vacuum distillation column.

Part of the solvent and aromatic components are distilled off from the top of the vacuum distillation column under conditions of OtmnHg and 200°C, and the mixture is introduced into the next solvent recovery column, where the bath agent is recovered from the top and recycled to the stirring tank. did.

Pitch was obtained from the bottom of the tower at a rate of 10jkg/Hr.

The physical property values are shown in Table/. In addition, as an example, the physical properties of pitch prepared under the same conditions as in Example 1 except that the tar-based oil was not canted back to the stratified and separated lower layer, and as a comparative example, the pitch was prepared from an ordinary tar continuous distillation column. Table 1 also shows the physical property values of the pitch that was heat-treated at 310° C./J hr.

Table 1 The product of the present invention has lower benzene-insoluble content and quinoline-soluble content compared to conventional products, but when used as an electrode binder, it has been found that its characteristic values are actually better, as shown in the following reference example. There is.

Reference Example 1 part by weight of pitch obtained in Example-/, λ and Comparative Example and 3.0 parts of needle coke. After kneading the weight parts in a kneader at 160℃ for 60 minutes, the diameter is Table λ shows the physical properties of the product, which was molded into a cylinder with a length of 100 m, fired at rθθ°C, and then graphitized at 3000°C.

It is clear that the graphitized product using the binder pitch of the present invention has superior characteristic values L2 as an electrode compared to those using the conventional pitch.

Table - λ

Claims (2)

[Claims] (1) A hydrocarbon substance containing a condensed cyclic aromatic compound from which a fraction with a boiling point of at least 0°C has been removed, and a boiling point or
A solvent such as an aliphatic hydrocarbon substance and/or an alicyclic hydrocarbon substance having a distillation temperature of 6j to 20°C is added to the solvent per part by weight of the hydrocarbon substance. ~70
Mix in proportions of parts by weight, then leave the mixture to stand, separate the layers by stratification, and directly distill the resulting lower layer, or mix tar-based oil with a boiling point of 220 ° C. or higher in the lower layer, and then distill it,
A method for producing binder pitch for electrodes, characterized in that pitch is obtained as a bottom fraction by distilling off the solvent. (2) The method according to claim 1, characterized in that when tar-based oil is mixed with the stratified lower layer and distilled, all of the solvent and part of the aromatic hydrocarbons are distilled off. .