JPH09104872A - Production of pitch for carbon material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To industrially and readily produce a binder pitch for carbon materials having high carbonization yield without increasing softening point. SOLUTION: A target softening point T0 of a pitch for carbon materials and an addition amount of carbonaceous powder are previously set and raising temperature ΔT of the softening point to an amount of added and mixed carbonaceous powder are estimated, and (A) a pitch raw material is heat-treated under heat treating conditions to reach a softening point T1 (=T0 -ΔT) and carbonaceous powder of previously set addition amount is added and mixed with the resultant heat-treated pitch or (B) the carbonaceous powder of the previously set addition amount is added to and mixed with the pitch raw material and the mixture is heat-treated under heat-treating conditions in which softening point of pitch obtained when the pitch raw material is singly heat- treated becomes the softening point T1 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pitch for carbon materials, particularly a binder pitch for carbon materials.

[0002]

2. Description of the Related Art Binder pitches made from coal tar or heavy petroleum oil are used in the production of graphite materials such as carbon materials or artificial graphite electrodes.
Usually, the method for producing a carbon material or a graphite material is as follows. That is, first, coke which is an aggregate and binder pitch are mixed with a kneader or the like under a temperature condition equal to or higher than the softening point of the binder pitch.

Next, using a pressing machine or the like, it is molded into a predetermined shape. Firing the obtained molded product under an inert atmosphere,
A fired body (carbon material) is obtained. Thereafter, if necessary, the impregnated pitch is used to fill (impregnate) the pores present in the fired body, and re-baking is repeated to achieve the required density and strength. When the graphitization treatment is required depending on the application, the graphite material is obtained by performing the graphitization treatment after the filling with the impregnated pitch and the re-baking.

Therefore, if the carbonization yield of the binder pitch is high, the density of the first-time fired body is increased, and the number of repetitions of impregnation and re-firing can be reduced, thus improving the productivity of carbon material or graphite material. It is possible to reduce the manufacturing cost. Regarding the method of increasing the carbonization yield of the binder pitch, Japanese Patent Laid-Open No. 51-122120 discloses that the low boiling point component is removed by distillation of the raw material coal tar and the low molecular weight component is polymerized by thermal treatment (thermal reforming). ) Is disclosed.

On the other hand, JP-A-50-112418 discloses a method for producing a binder pitch for electrodes in which carbon black is added to coal tar pitch and then heat treated. By these methods, it is possible to increase the carbonization yield of the binder pitch, but on the other hand, the softening point of the pitch obtained is increased, so that it is difficult to mold the carbon material. There is.

Therefore, in producing the binder pitch for a carbon material, it is desired to increase the carbonization yield without increasing the softening point.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and makes it easy to industrially provide a binder pitch for a carbon material having a high carbonization yield without increasing the softening point. It is an object to provide a manufacturable method.

[0008]

A first aspect of the present invention is a method for producing a pitch for carbon material, in which carbonaceous powder is added to and mixed with a heat-treated pitch, and a target softening point T of the pitch for carbon material is previously set.
₀ and the addition amount of the carbonaceous powder are set, the softening point increase ΔT corresponding to the addition amount of the carbonaceous powder added and mixed in the heat treatment pitch is predicted, and the softening point increase amount from the target softening point T ₀ is estimated. Softening point T ₁ (= T ₀ −ΔT) after subtracting ΔT
The pitch raw material is heat-treated under the following heat treatment conditions, and a preset addition amount of carbonaceous powder is added to and mixed with the obtained heat-treated pitch.

A second aspect of the present invention is a method for producing a pitch for a carbon material, in which a carbonaceous powder is added to and mixed with a pitch raw material, and then heat treated, wherein a target softening point T ₀ and a carbonaceous material of the pitch for the carbon material are previously prepared. The softening point increase amount ΔT corresponding to the addition amount of the carbonaceous powder to be added to and mixed with the pitch raw material is predicted, and the softening point increase amount ΔT is subtracted from the target softening point T ₀ . Softening point T ₁ (= T ₀ −ΔT)
Under a heat treatment condition such that a preset amount of carbonaceous powder is added to and mixed with the pitch raw material, and the softening point of the pitch obtained when the mixture is heat-treated is the softening point T _1. A method for manufacturing a carbon material pitch, which is characterized by heat treatment.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Usually, when a pitch raw material such as coal tar or heavy petroleum oil is distilled or thermally reformed to produce pitch, the carbonization yield increases, but at the same time, the softening point also rises.

The inventor of the present invention increases both the softening point and the carbonization yield when carbonaceous powder is added to and mixed with the heat-treated pitch.
It was found that it is larger than the case of only distillation or thermal reforming. Figure 3 shows the distillation and thermal reforming of coal tar (270,
The relationship between the carbonization yield and the softening point of the pitch (coal tar distillation / heat reformed product) prepared by 300 ° C., 330 ° C. and heat treatment time of 3 hours is shown.

Further, 100 parts by weight of pitch having a softening point of 90 ° C. and a carbonization yield of 52 wt% was mixed with 1, 5, 10, 20 parts by weight of free carbon separated from coal tar as a solid content using a kneader. FIG. 3 also shows the relationship between the softening point and the carbonization yield of the pitch (pitch-free carbon mixed product) prepared in this way. As is clear from FIG. 3, the pitch obtained by adding and mixing free carbon, which is a carbonaceous powder, was higher than the pitch obtained by distilling and thermal reforming coal tar and the carbonization yield with respect to the amount of increase in the softening point. The rate of increase in rate is large.

Furthermore, free carbon is added to coal tar.
The relationship between the softening point of the pitch prepared by distillation and thermal reforming after 10 parts by weight addition and mixing and the carbonization yield is shown in FIG. 4 together with the case where no free carbon was added. As is clear from FIG. 4, the pitch prepared by distillation and thermal reforming after adding and mixing free carbon to coal tar has a carbonization yield value at the same softening point as compared with the pitch without adding free carbon. large.

The present inventor has found the method for producing the binder pitch for a carbon material of the present invention based on the above findings. Hereinafter, the first invention and the second invention will be described in order. [First invention:] The first invention is a pitch obtained by heat-treating a pitch raw material (hereinafter referred to as pitch raw material) which is coal tar and / or petroleum heavy oil (hereinafter referred to as heat-treated pitch). Is a method for manufacturing a pitch for carbon material, which has a basic step of adding and mixing carbonaceous powder.

In the first aspect of the present invention, a first embodiment described later is provided.
As shown in, a diagram or a relational expression regarding heat treatment conditions such as a heat treatment temperature, an addition amount of carbonaceous powder, and a softening point, which are obtained in advance by experiments, can be used. FIG. 1 shows a flowchart of a method for producing a binder pitch for carbon material of the first invention.

That is, the present invention is specifically carried out by the following procedures [A] to [F]. [A]: Target softening point T _{0 of} binder pitch for carbon material
Is set in advance. Here, the target softening point T ₀ of the binder pitch for carbon material is selected according to the required characteristics of the carbon material or graphite material. In the case of ordinary carbon materials or graphite materials, T ₀ is preferably in the range of 90 to 120 ° C.

[B]: The amount of carbonaceous powder added to the heat-treated pitch in the subsequent step [F] is set in advance. The addition amount of the carbonaceous powder can be set based on the difference between the target value of the carbonization yield of the binder pitch for carbon material and the carbonization yield of the heat treatment pitch used. The addition amount is preferably 1 to 50 parts by weight with respect to 100 parts by weight of the heat treatment pitch.

If the addition amount of the carbonaceous powder is less than 1 part by weight, the effect of the addition, that is, the improvement of the carbonization yield is not sufficient, and if the addition amount exceeds 50 parts by weight, the softening point of the obtained binder pitch for carbon material is increased. It rises remarkably, and it becomes difficult to control the softening point. The steps [A] and [B] are not limited to the procedure shown in the flowchart of FIG.
The step [B] may be performed before the step [A].

[C]: Predict the softening point increase ΔT due to the addition of the carbonaceous powder in the addition amount set in [B]. As a method of this prediction, it is possible to make a prediction based on the relationship between the amount of carbonaceous powder added to the pitch and the amount of increase in the softening point of the pitch, which is obtained in advance by an experiment, as shown in FIG. .

[D]: A softening point T ₁ = T ₀ −ΔT is obtained by subtracting the softening point increase ΔT from the target softening point T ₀ . [E]: Using the pitch raw material, heat treatment is performed under heat treatment conditions such that the pitch of the softening point T ₁ is obtained when the heat treatment is performed without adding carbonaceous powder, and a heat treated pitch is obtained.

As a specific method of controlling the heat treatment conditions,
Control of heat treatment temperature, heat treatment time, gas blowing amount, etc. is exemplified. For example, a relationship diagram between the heat treatment temperature / time and the softening point of the pitch obtained in advance used in Example 1 described later (FIG. 3)
On the basis of the above, the temperature at which the softening point of the pitch obtained by heat-treating the pitch raw material with no carbonaceous powder becomes the softening point T ₁
The pitch raw material may be heat-treated under the condition of time.

[F]: To obtain the binder pitch for a carbon material of the present invention by adding and mixing the amount of carbonaceous powder preset in [B] to the heat treatment pitch obtained in [E]. You can As the carbonaceous powder, it is preferable to use carbonaceous powder selected from carbon black, graphite powder, coke powder, solid content in coal tar (free carbon), or a mixture thereof.

As a method for mixing the heat-treated pitch and the carbonaceous powder, an industrially used mixing method such as a kneader is used. In the first aspect of the present invention, the mixing temperature is set to a value equal to or higher than the softening point of the heat-treated pitch and equal to or above the softening point +10.
It is preferably within the range of 0 ° C. or lower. The first invention makes it possible to obtain a binder pitch for a carbon material having a low softening point and a high carbonization yield.

Further, the obtained binder pitch for carbon material matches the target softening point and also has the effect of improving the yield. [Second invention:] A second invention is coal tar and / or
Alternatively, it is a method for producing a pitch for a carbon material, which has a basic step of adding a carbonaceous powder to a pitch raw material which is a petroleum-based heavy oil, and then performing a heat treatment.

In the second aspect of the present invention, a second embodiment described later is provided.
As shown in, a diagram or a relational expression regarding heat treatment conditions such as a heat treatment temperature, an addition amount of carbonaceous powder, and a softening point, which are obtained in advance by experiments, can be used. FIG. 2 shows a flowchart of the method for producing the binder pitch for carbon material of the second invention.

That is, the present invention is specifically carried out by the following procedures [A] to [G]. [A]: Target softening point T _{0 of} binder pitch for carbon material
Is set in advance. Here, the target softening point T ₀ of the binder pitch for carbon material is selected according to the required characteristics of the carbon material or graphite material. In the case of ordinary carbon materials or graphite materials, T ₀ is preferably in the range of 90 to 120 ° C.

[B]: pitch original in the subsequent step [F]
Amount of carbonaceous powder added to the powder X ₀Is set in advance.
Addition amount of the carbonaceous powder X₀Is a pitch-based carbonaceous powder
Addition amount of powder and pitch yield obtained by heat treatment of pitch raw material
It can be set from the rate. The addition amount is preferably
It is 1 to 50 parts by weight with respect to 100 parts by weight of the starting material.

If the amount of the carbonaceous powder added is less than 1 part by weight, the effect of the addition, that is, the improvement of the carbonization yield is not sufficient, and if the amount added exceeds 50 parts by weight, the softening point of the binder pitch for carbon material obtained is It rises remarkably, and it becomes difficult to control the softening point. [C]: The pitch-based carbonaceous powder addition amount X based on the pitch yield is obtained in consideration of the pitch yield obtained by heat-treating the pitch raw material.

Specifically, the pitch-based carbonaceous powder addition amount X is determined from the following equation (1). Amount of carbonaceous powder based on pitch X (parts by weight) [100 parts by weight of pitch] = [Amount of carbonaceous powder added to 100 parts by weight of pitch material X ₀ (parts by weight)] × (100 / Y) .. (1) In the formula (1), Y represents the pitch yield (%) obtained by heat-treating the pitch raw material.

[D]: Based on the value of X obtained in [C], the softening point increase ΔT due to the addition of carbonaceous powder is predicted. As a method of this prediction, it is possible to make a prediction based on the relationship between the amount of carbonaceous powder added and the amount of increase in the softening point, which is previously obtained by experiments, and the value of X, as shown in FIG. Is.

[E] The target softening point T₀From the softening point
Softening point T minus ΔT₁= T ₀-Calculate ΔT. [F]: The amount (X
₀) Carbonaceous powder is added and mixed. As carbonaceous powder
The same as the first invention can be used.

As a method for mixing the pitch raw material and the carbonaceous powder, there are used industrially practiced mixing methods such as mechanical stirring and circulation mixing with a pump. [G]: By heat-treating the mixture of the pitch raw material and the carbonaceous powder obtained in the previous step under heat treatment conditions such that the softening point of the pitch obtained by heat-treating only the pitch raw material is T _1. The binder pitch for carbon material of the invention can be obtained.

That is, the pitch softening point obtained when the pitch raw material to which the carbonaceous powder obtained in the above-mentioned step is added is heat treated alone is T ₁ (= T ₀ -ΔT).
Heat treatment is performed under the following heat treatment conditions. As a specific method for controlling the heat treatment conditions, control of the heat treatment temperature, the heat treatment time, the amount of gas blown, and the like are illustrated.

For example, based on the relationship diagram (FIG. 3) between the heat treatment temperature and time of the pitch and the softening point obtained in advance used in Examples 1 and 2 described below, after heat treatment of the pitch raw material with no carbonaceous powder added The mixture of the pitch raw material and the carbonaceous powder may be heat-treated at a temperature and for a time such that the softening point of the pitch becomes the softening point T ₁ . The steps [A] and [B] are not limited to the procedure shown in the flowchart of FIG.
The step [B] may be performed before the step [A].

The second invention makes it possible to obtain a binder pitch for a carbon material having a low softening point and a high carbonization yield. Further, the obtained binder pitch for carbon material matches the target softening point, and also has the effect of improving the yield.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. In this example, the softening point of the pitch was measured by the Ring and Ball method (Ring & Ball method), and the carbonization yield (fixed carbon amount) was measured by the JIS method. (Example 1) [Example relating to the first invention] Coal tar containing 1% by weight of free carbon (evaluated as quinoline insoluble content) was heat-treated, and then carbonaceous material was added to 100 parts by weight of the obtained heat-treated pitch. In the method for producing a pitch for carbon material in which 10 parts by weight of powder is added and mixed, the target softening point T ₀ of the pitch for carbon material is set to 120 ° C.

From FIG. 3, the softening point increase ΔT due to the addition and mixing of the carbonaceous powder was predicted to be 20 ° C. Therefore, the softening point of the pitch should be T ₁ = 120 ° C.-20 ° C. = 100 ° C. Prepared. That is, the raw material pitch obtained by heat-treating coal tar in advance is subjected to 270 ° C, 300 ° C, 330 ° C under normal pressure.
Then, heat treatment was performed for 3 hours, and FIG. 5 showing the relationship between the heat treatment temperature and the softening point of the pitch after the heat treatment was obtained.

Similarly, the raw material pitch obtained by heat treatment of coal tar was heat-treated at 285 ° C. for 3 hours with a target of a softening point T ₁ = 100 ° C. based on FIG. 5 to prepare a pitch having a softening point of 98 ° C. did. To 100 parts by weight of the heat-treated pitch thus obtained, 10 parts by weight of free carbon separated as solids from coal tar was added and mixed to obtain a binder pitch for carbon material.

The softening point of the obtained binder pitch for carbon material was 119 ° C., and the carbonization yield was 62.5 wt%. The relationship between the softening point and the carbonization yield is shown in FIG. 6 in comparison with a coal tar distillation / thermal reforming product containing no free carbon. As is clear from FIG. 6, by the addition and mixing of carbonaceous powder and the heat treatment method of the present invention, a high carbonization yield is obtained at the same softening point as the coal tar distillation / thermal reforming product, and the target softening point is also obtained. A binder pitch for a carbon material having a softening point almost equal to T ₀ = 120 ° C. could be manufactured.

(Example 2) [Example relating to the second invention] To 100 parts by weight of coal tar used in Example 1, 10 parts by weight of free carbon separated as a solid content from coal tar was added and mixed. The pitch yield Y of the coal tar used was 50 wt%, and the amount of free carbon added in the pitch was
That is, the pitch-based carbonaceous powder addition amount X is calculated by the above formula (1).
Therefore, it is estimated to be 20 parts by weight for 100 parts by weight of the pitch.

From FIG. 3, the softening point increase ΔT due to the addition and mixing of the carbonaceous powder was predicted to be 40 ° C. Therefore, the softening of the pitch for the target softening point T ₀ = 120 ° C. So that the point becomes T ₁ = 120 ℃ -40 ℃ = 80 ℃,
That is, based on FIG. 5 obtained in advance in Example 1, conditions for performing heat treatment at 250 ° C. for 3 hours were selected with a softening point of 80 ° C. as a target.

That is, 100 parts by weight of coal tar was mixed with free carbon separated from coal tar as a solid content.
After adding 10 parts by weight and mixing, heat treatment was carried out at 250 ° C. for 3 hours to obtain a binder pitch for carbon material. The obtained binder pitch for carbon material has a softening point of 118 ° C and a carbonization yield of 66.8 wt.
%Met.

The relationship between the softening point and the carbonization yield is shown in FIG. 6 in comparison with a coal tar distillation / thermal reforming product containing no free carbon. As is clear from FIG. 6, by the addition and mixing of the carbonaceous powder and the heat treatment method of the present invention, a high carbonization yield is obtained at the same softening point as the coal tar distillation / thermal reforming product, and the target softening point is also obtained. A binder pitch for a carbon material having a softening point almost equal to T ₀ = 120 ° C. could be manufactured.

[0044]

According to the present invention, it becomes possible to produce a binder pitch for a carbon material with a high carbonization yield without increasing the softening point. That is, according to the production method of the present invention, since the softening point of the obtained pitch is not different from the conventional one, for example, the moldability is not deteriorated at the time of molding the mixture of the coke and the binder pitch, and the carbonization yield is increased. It is possible, as a result, impregnation of the impregnated pitch,
It is possible to reduce the number of repetitions of re-baking, and it is possible to reduce the manufacturing cost of the carbon material or the graphite material.

Further, according to the production method of the present invention, it is possible to adjust the target softening point of the binder pitch required at the time of producing the carbon material or the graphite material, and also it has an effect of improving the yield and has a great industrial value. is there.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a method for producing a binder pitch for carbon material of the present invention.

FIG. 2 is a flowchart showing a method for producing a binder pitch for carbon material of the present invention.

FIG. 3 is a graph showing the relationship between pitch softening point and carbonization yield.

FIG. 4 is a graph showing the relationship between pitch softening point and carbonization yield.

FIG. 5 is a graph showing the relationship between the heat treatment temperature of pitch and the softening point.

FIG. 6 is a graph showing the relationship between pitch softening point and carbonization yield.

Claims (2)

[Claims] 1. A method for producing a pitch for carbon material, wherein carbonaceous powder is added to and mixed with heat treated pitch, wherein the target softening point T _{0 of the} pitch for carbon material and the addition amount of carbonaceous powder are set in advance, and the heat treated pitch is set. The softening point increase ΔT corresponding to the addition amount of the carbonaceous powder added and mixed to the target softening point T ₁ (= T ₀ −ΔT) is calculated by subtracting the softening point increase ΔT from the target softening point T _0. ), The pitch raw material is heat-treated, and a preset addition amount of carbonaceous powder is added to and mixed with the obtained heat-treated pitch. 2. A method for producing a pitch for a carbon material, comprising adding carbonaceous powder to a pitch raw material and mixing it, followed by heat treatment.
The target softening point T ₀ of the carbon material pitch and the addition amount of the carbonaceous powder are set in advance, the softening point increase ΔT corresponding to the addition amount of the carbonaceous powder added and mixed to the pitch raw material is predicted, and the target is set. seeking a softening point T ₀ softening point minus the softening point rise ΔT from _{T 1 (= T 0 -ΔT)} , were added to and mixed with carbonaceous powder added amount set in advance in the pitch feed, the mixture, wherein A method for producing a pitch for a carbon material, which comprises heat-treating under a heat treatment condition such that a softening point of the pitch obtained when only the pitch raw material is heat-treated becomes the softening point T ₁ .