JPH0693270A - Production of rodlike pitch - Google Patents

Abstract

PURPOSE:To obtain rodlike pitch of high mechanical strength, good in handleability, formable in any dimension, by regulating the viscosity of coal- or petroleum-based molten pitch within a specific range followed by extruding the molten pitch through a die and then cutting it to a specified length. CONSTITUTION:Using a cool forming device 1 consisting of a double pipe made up of an outer pipe 1a and inner pipe 1b, the outer pipe 1a is injected with cooling water at 80 deg.C, while the inner pipe 1b with coal- or petroleum-based molten pitch, through a high-pressure pump 4 to regulate the viscosity of the pitch to 1000-100000 poise followed by horizontally extruding the pitch via a circular die 20mm in diameter into the air, and the pitch is then cut to a specified length using a guillotine cutter 3; the resultant rodlike pitch 8 is carried under air cooling on a belt conveyor 7 and allowed to fall into the water in a cooling tank 9 to effect complete solidification, thus obtaining the rodlike pitch having the above-mentioned advantages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a rod-shaped pitch.

[0002]

2. Description of the Related Art There are various conventional methods for producing solid pitch ("Aromatic and Tar Industry Handbook", December 1978, published by Japan Aromatic Industry Association). Among them, in the vertical cooling tank type as a method of manufacturing the rod-shaped pitch, after cooling the pitch manufactured in the previous step to some extent, it is made to flow out and fall from the pitch nozzle into the water in the cooling tank, thereby cooling the solidified pitch in the rod shape. It is cut by a screw conveyor with a cutter provided near the bottom of the tank and is carried out of the cooling tank by a bucket elevator. The final product was obtained by drying these pellets.

However, in the conventional method for manufacturing a rod-shaped pitch as described above, since the pitch may be cut by the cutter many times in the cooling tank, the powder may be cut when the rod-shaped pitch is cut. However, there are problems such as generation of debris, poor yield, and poor working environment. Also,
This rod-shaped pitch has corners (edges) on the end surface, and during transportation work, etc., this end surface is crushed and pulverized,
There were problems such as a decrease in product yield, a decrease in product quality, and a bad working environment. Further, such a pitch has a problem that the diameter of the bar is small because it is rapidly cooled and solidified, and holes, cavities, or moisture are likely to remain inside and the strength is weak.

As a method of solving this problem, there is a method of making the pitch shape spherical, for example, Japanese Patent Publication No. 60-10.
No. 1190, Japanese Patent Publication No. 61-23957, JP-A No. 63-
It is disclosed in Japanese Patent No. 139981.

However, in these methods, the pitch obtained is not rod-like but spherical or an analogue thereof, and the spherical product is more vulnerable to drop impact (prone to powdering) than the rod-like product, and has a rest position. Since the corners are small, there is a problem in handling characteristics that it is unstable during storage (the pile height cannot be increased). In addition, the pitch of molten state with low viscosity is extruded into the water in the cooling tank, and at the same time as it is extruded, it is deformed by resistance due to water, and residual stress and internal voids are generated due to large density change during rapid cooling and solidification. There is a problem that there is a high possibility that defects are likely to occur.

In addition, in the conventional method, the viscosity of the molded product is generally low, and there are problems in moldability including the cutting cross section. Further, in the bar-shaped pitch, a limited bar diameter ( (15 mmφ or less), the length will naturally break, and the rod diameter and rod length can be controlled as desired to obtain a rod diameter of 20
It has been impossible to stably manufacture a large-diameter product having a diameter of about mmφ.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, is excellent in moldability, has a good shape, does not have a deformed product in the product, and has no end surface corners (edges). To provide a method for producing a rod-shaped pitch that does not have water content, is less likely to be broken by residual stress and internal voids after molding, powdering, and is excellent in handling characteristics and can be formed into a rod-shaped pitch with arbitrary dimensions. The purpose is.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to achieve the above-mentioned object, and as a result, after adjusting the viscosity of the molten pitch to a high viscosity range which has not been conventionally performed, extruding from a die, The present invention has been completed by finding that cutting can be excellent in moldability and compactness of a molded body and the shape (bar diameter, bar length) can be controlled by cutting.

That is, according to the present invention, when the rod-shaped pitch is cooled and solidified from the coal-based or petroleum-based molten pitch, the viscosity of the molten pitch is adjusted to 1,000 to 100,000 poise and then the molten pitch is extruded from the die to obtain a predetermined length. The present invention provides a method for manufacturing a rod-shaped pitch, which is characterized by cutting into pieces. Here, at the time of extrusion after adjusting the viscosity, it is desirable to extrude the melt pitch under pressure, and it is preferable to use a heated die as the extrusion die.

[0010]

The present invention will be described in more detail below. First,
One of the embodiments of the present invention will be described with reference to FIGS. 1 and 2. Similar parts in these figures are indicated by the same reference numerals. In the example of FIG. 1, a double-tube high-pressure extruder is used as a melt pitch viscosity adjuster, the extrusion direction is horizontal, and the cutting method is a guillotine method or a rotary blade, and the example of FIG. 2 is a viscosity adjuster. This is a configuration example in which a heavy-duty high-pressure extruder is used, the extrusion direction is downward, and the cutting method is roll cutting.

More specifically, in the above configuration example, the cooling molding apparatus main body 1 is a double tube consisting of an outer tube 1a and an inner tube 1b, and a temperature-controlled cooling medium is melted in the outer tube 1a and the inner tube 1b. Pitch is flown and viscosity is 1,000-100,00
0 Poise molding After cooling to a high viscosity that can be maintained and molding with a molding die 2, it is laterally pushed into the air by a high-pressure pump 4 and cut to an arbitrary length with a cutting device (guillotine method or rotary blade 3 or roll cutting method 11). Cut. Cut rod pitch 8
Is conveyed by air cooling on the belt conveyor 7 and naturally falls into the water in the cooling tank 9 to be completely solidified. The outer pipe 1a is supplied with a coolant by the coolant unit 5 and the temperature control cooling device, and cools the molten pitch in the inner pipe 1b. Also,
The die 2 may be heated by the heating device 10 so that the melted pitch that has been cooled and increased in viscosity can be more easily extruded.

FIG. 3 shows still another example. In this example, the cooling molding apparatus main body 1 is an extrusion molding machine, and an outer pipe 1a for flowing a refrigerant and an inner pipe 1 for flowing a molten pitch.
b is substantially the same as that shown in FIG. 2 except that the screw 1c forcibly feeds the molten pitch that is being cooled. In this example, pressure is applied by the screw 1c operated by the screw motor 12.
The pitch can be extruded while mixing. In this case as well, it goes without saying that the die 2 may be heated by the heating device 10.

In the example shown in FIG. 4, the cooling molding apparatus body 1 is
An example is a static mixer for eliminating the temperature gradient in the inner tube of the molten pitch by stirring the outer tube 1a for flowing the refrigerant, the inner tube 1b for flowing the molten pitch, and the pitch sent by the high-pressure pump 4. The configuration is substantially the same as that of FIG. 2 except that the configuration is the mixer 1d.

In the system shown in FIGS. 3 and 4, the molten pitch is in the high viscosity region immediately before solidification, in other words, the viscous deformation point (Ring & Ba).
By gradually cooling while mixing to the softening point (below the ll method), it became possible to eliminate the temperature gradient inside the pitch, reduce residual stress, and increase the strength of the pitch. Further, by passing the refrigerant through the screw 1c of FIG. 3 and the static mixer 1d of FIG. 4, the pitch can be cooled and the temperature can be made more uniform.

Here, a temperature gradient (for example, pitch surface-
The relationship between the center temperature difference / bar radius) and strength will be briefly supplemented. In general, the thermal stress is proportional to the temperature gradient, so that the larger the temperature gradient, the larger the thermal stress. If it is a perfect elastic body with no physical property deformation point, the thermal stress generated during heating and cooling should disappear by itself when the entire surface finally becomes uniform at a constant temperature, but it becomes plastic during the constant temperature. When deformation or viscous deformation is involved, thermal stress remains and residual stress occurs. In the case of pitch, there is a viscous deformation point (in other words, a softening point in Ring & Ball method) in the process of complete solidification until it reaches a constant temperature, so it is considered that thermal stress remains as residual stress. Therefore, if the temperature gradient in the cooling process is large, the residual stress will be large and the strength will be weakened.
Gradual cooling in the viscous deformation temperature range is very effective in improving the strength of the pitch.

In addition, by high pressure pumping or torque pumping, it becomes possible to eliminate pores, cavities and internal water inside the pitch and to densify the structure, which greatly contributes to the improvement of pitch strength. To do.

In the above method, after gradually cooling the inside of the apparatus, the tip molding portion is heated to locally warm only the pitch surface, so that the pitch surface is fixed to the inner wall of the molding pipe (die) at the tip and the resistance due to sticking or the like occurs. It can be stably processed continuously without having.

In any of the methods, by cooling to a high viscosity immediately before solidification and cutting, since it has moldability, deformation due to cutting is eliminated. On the other hand,
Due to the surface tension of the pitch, the cut surface does not have angular portions (edges) and has a rounded shape, which has the effect of making it difficult to pulverize. In addition, by using a rod-shaped product, it is vulnerable to drop impact (prone to powdering), which is a problem of spherical products, and unstable at storage (the pile height cannot be increased) due to a small angle of repose. It is also effective in eliminating problems. Further, the shape (bar diameter, bar length) can be controlled by arbitrarily setting the hole diameter of the molding die or the operation (rotation speed) of the cutter blade.

In the present invention, the viscosity range of the molten pitch is set to 1,000 to 100,000 poise for the following reason. That is, if it is less than 1,000 poise, the slow cooling in the apparatus at the viscous deformation point becomes insufficient, the effect of improving the strength cannot be obtained, and the moldability and the cutting property are deteriorated, which is not preferable. On the other hand, when the porosity exceeds 100,000, the solidified state is too advanced, so that it is difficult to carry out cutting and molding, edges are likely to occur on the cut surface, and the pressure and torque required for the treatment are excessive, which is not practical.

[0020]

EXAMPLES The present invention will be specifically described below based on examples.

Example 1 Softening Point (Ring & Ball Method JI
SK 2425) melted pitch of 108 ° C was cooled to 80 ° C in the outer pipe and melted in the inner pipe by a double pipe cooling machine, and the viscosity was adjusted to 20,000 poise.
A die with a circular cross section of 0 mm was pushed laterally into the air by a high-pressure pump, cut with a guillotine blade, air-cooled and conveyed by a belt conveyor, and then naturally dropped into the water in a cooling tank, with a diameter of 20 mm and a length of 100 mm. A bar pitch was obtained. The pitch processing amount at this time is 40 to
It was 50 kg / hr.

(Embodiment 2) Softening point (Ring & Ball method JI
SK 2425) melted pitch of 108 ° C is made to flow into the screw part by a screw extrusion type cooling molding device, cooled with normal temperature cooling water, adjusted to a viscosity of 20,000 poise, and then a die with a circular cross section of 20 mm in diameter. Further, it was extruded downward in the air by screw extrusion, cut by roll cutting, and allowed to fall naturally in the water in the cooling tank to obtain a rod-shaped pitch having a diameter of 20 mm and a length of 100 mm. The pitch processing amount at this time is 40 to
It was 50 kg / hr.

In each of Examples 1 and 2, the shape was good, the cutting surface had no edges, and the cross section of the cylinder was examined. As a result, cavities, holes, internal moisture, etc. were not observed. On the other hand, when the pulverization state by dropping was compared, the pulverization rate was reduced as shown in Table 1 as compared with the bar pitch manufactured by the conventional method. Furthermore, when the rod length was changed by changing the cutting speed, it was possible to cut within the range of rod diameter / rod length = 1/1 to 1/100. By replacing the nozzle, it is also possible to control the rod diameter independently.

[0024]

[Table 1]

(Embodiment 3) Softening point (Ring & Ball method JI
SK 2425) uses a jacket-type double pipe cooling device to melt the molten pitch of 108 ° C to the outside (jacket) of 60-
Cooled hot water of 80 ° C is flowed, and the molten pitch is pumped inside by a high-pressure pump, and the pitch temperature is about 98 ° C (viscosity: 20,000 ~
While adjusting the pressure to about 20,000 poise), it was extruded and molded by a molding die having a circular cross section with a diameter of 20 mm. At this time, the required pressure of the high-pressure pump was 50 to 200 kg / cm ² , and the pitch processing amount was 40 to 50 kg / hr per heat transfer tube.
At this time, the molding die portion was slightly heated by adjusting the temperature (heat transfer trace: about 110 ° C.). The extruding direction from the die was the same regardless of whether it was a horizontal method in the air or a vertically downward direction. It was confirmed that good cutting was possible without leaving an edge on the cut surface by using either a guillotine blade system that moves up and down or a roll cutting system that uses a rotary blade for cutting the pitch molded body. The rod-shaped pitch thus manufactured was conveyed by a belt conveyor and completely cooled in a water tank. At this time, no difference was observed with or without air cooling time (it is also possible to process directly in the water tank after cutting). The rod-shaped pitch thus obtained has a diameter of 20 mmφ (die diameter) and a length of 50-
It was 100 mm.

The pitch prototyped by this method had a uniform and good shape and had no edges on the cutting surface, and when a cross section of a cylinder was examined, cavities, holes, internal moisture, etc. were not observed. Table 2 shows the results of measurement of bending strength (JIS 7202) in order to compare pitch strength. Here, as a comparative example, the bending strength measurement results of a pitch (rod diameter 14 mmφ) in which a molten pitch of 180 ° C. is directly flown in a molten state in a water tank and cooled and solidified into a rod shape by rapid cooling is also shown. Bending strength measurement results (maximum load actual measurement value)
Is affected by the diameter of the pitch, and it can be said that this value indicates the effect of slow cooling when compared with the relative evaluation value (in Table 2) in which the effect of the diameter is corrected. From these results, it was confirmed that the pitch produced by the method of the present invention (double pipe molding) had higher strength than the conventional product and the effect of slow cooling was observed. Also, when the rod length was changed by changing the cutting speed, the rod diameter / bar length = 1
Cutting was possible in the range of / 1 to 1/100.
By changing the nozzle size, the rod diameter itself could be controlled independently, and it became possible to manufacture pitches with a larger diameter than before.

[0027]

[Table 2]

(Embodiment 4) Softening point (Ring & Ball method JI
SK 2425) controls the melt pitch of 108 ° C by a screw extruder and the temperature of the outer cylinder part (7 places) by cooling water and a heater at room temperature. Viscosity: 20,000
While adjusting to about 30,000 poise), it was extruded with a circular die having a diameter of 20 mm and molded. The screw rotation speed at this time was 30 to 100 rpm, and the pitch processing amount was 30 to 140 kg / hr (varied depending on the screw rotation speed). At this time, the molding die portion was slightly heated by adjusting the temperature (heat transfer trace: about 110 ° C.). The extrusion state from the die was the same regardless of whether it was in the horizontal direction in the air or vertically downward. The pitch molded body can be cut either by the vertically moving guillotine blade method or the rotary blade roll cutting method.
It was confirmed that good cutting was possible without leaving an edge on the cut surface. The rod-shaped pitch thus manufactured was conveyed by a belt conveyor and completely cooled in a water tank. At this time, no difference was observed with or without air cooling time (it is also possible to process directly in the water tank after cutting). The rod-shaped pitch thus obtained had a diameter of 20 mmφ (die diameter) and a length of 50 to 100 mm.

The pitch prototyped by this method had a uniform and good shape and had no edges on the cutting surface, and when a cross section of a cylinder was examined, cavities, holes, internal moisture and the like were not observed. Table 3 shows the results of measurement of bending strength (JIS 7202) in order to compare pitch strength. Here, as a comparative example, the bending strength measurement results of a pitch (rod diameter 14 mmφ) in which a molten pitch of 180 ° C. is directly flown in a molten state in a water tank and cooled and solidified into a rod shape by rapid cooling is also shown. Bending strength measurement results (maximum load actual measurement value)
Is affected by the diameter of the pitch, and it can be said that when compared with the relative evaluation value (in Table 3) in which the effect of the diameter is corrected, this numerical value shows the effect of slow cooling. From these results, the strength of the pitch produced by the method of the present invention (screw extrusion molding) was higher than that of the conventional product, and the effect of slow cooling was confirmed. Also,
When the bar length was changed by changing the cutting speed, it was possible to cut within the range of bar diameter / bar length = 1/1 to 1/100. By changing the nozzle size, the rod diameter itself could be controlled independently, and it became possible to manufacture pitches with a larger diameter than before.

[0030]

[Table 3]

[0031]

EFFECTS OF THE INVENTION According to the present invention, unlike the prior art, since the molten pitch is gradually cooled to increase its viscosity and then extrusion-molded, residual stress and voids inside the pitch after molding are significantly reduced. For this reason, the pitch is excellent in strength and is less likely to be powdered or deteriorated during handling. As a result, great effects such as improvement of manufacturing yield, improvement of working environment, and improvement of handling property can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining an example of a melt pitch extrusion molding method of the present invention.

FIG. 2 is a schematic view for explaining another example of the melt pitch extrusion molding method of the present invention.

FIG. 3 is a schematic view for explaining still another example of the melt pitch extrusion molding method of the present invention.

FIG. 4 is a schematic view for explaining still another example of the melt pitch extrusion molding method of the present invention.

[Explanation of symbols]

 1 Cooling molding apparatus main body (pressure resistant jacket type double tube) 1a Outer tube 1b Inner tube 1c Screw 1d Mixer 2 Molding die 3 Cutting device (guillotine type) 4 High pressure pump 5 Refrigerant unit 6 Temperature control cooling device 7 Belt conveyor 8 Rod-shaped Pitch 9 Cooling water tank 10 Heating device 11 Cutting device (roll cutting method) 12 Screw motor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masao Tsuzaki Masao Tsuzaki Kurashiki City, Okayama Prefecture Mizushima Kawasaki Dori 1-chome (no address) Inside the Mizushima Works, Kawasaki Steel Co., Ltd. (72) Masayuki Ando Kurashiki City, Okayama Prefecture Mizushima Kawasaki Dori 1-chome (without street number) Kawasaki Steel Works Mizushima Steel Works

Claims (4)

[Claims] 1. When cooling and solidifying a rod-shaped pitch from a coal-based or petroleum-based molten pitch, the viscosity of the molten pitch is adjusted to 1,000 to 100,000 poise, and then the molten pitch is extruded from a die and cut into a predetermined length. A method for manufacturing a rod-shaped pitch, which is characterized by the following. 2. When the rod-shaped pitch is cooled and solidified from a coal-based or petroleum-based molten pitch, the viscosity of the molten pitch is adjusted to 1,000 to 100,000 poise, and then the molten pitch is extruded under pressure from a die to obtain a predetermined length. A method for manufacturing a rod-shaped pitch, which comprises cutting into pieces. 3. When cooling and solidifying a rod-shaped pitch from a coal-based or petroleum-based molten pitch, the viscosity of the molten pitch is adjusted to 1,000 to 100,000 poise and then the molten pitch is extruded from a heated die to a predetermined length. A method for manufacturing a rod-shaped pitch, which is characterized by cutting into pieces. 4. When cooling and solidifying a rod-shaped pitch from a coal-based or petroleum-based molten pitch, the viscosity of the molten pitch is adjusted to 1,000 to 100,000 poise, and then the molten pitch is extruded from a heated die under pressure. A method for manufacturing a rod-shaped pitch, which comprises cutting to a predetermined length.