JPH0575023B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a thermosetting carbon precursor having a high carbonization yield using pitch as a starting material.

(Prior Art) Phenol resins, furan resins, and the like are conventionally known as thermosetting carbon precursors. Also,
Pitch is inherently non-thermosetting and has thermoplasticity, but there is a conventionally known method for oxidizing and infusibleizing pitch using oxygen, ozone, sulfur, and various oxidizing agents to remove thermoplasticity. It is being

(Problems to be Solved by the Invention) When a thermosetting phenolic resin, furan resin, etc. is used as a carbon precursor to obtain a carbon graphite material by firing, the carbon precursor may melt during carbonization. It has the advantage that it easily maintains its shape during molding because it carbonizes as a solid without any carbonization, and that the properties of the obtained carbonaceous substance are uniform without being affected by weight. However, on the other hand, the carbonization yield is low. It not only shows a large volumetric shrinkage upon carbonization, but also has the disadvantage that the properties of the obtained carbon are limited. In other words, carbon obtained from phenolic resins, furan resins, etc. is a carbonaceous substance called glassy carbon that is extremely difficult to graphitize, and its structure hardly changes even after graphitization treatment, and its electrical conductivity and It lacks the properties of graphite such as thermal conductivity and machinability. In addition, when trying to obtain carbon raw materials by using these as carbon precursors, the carbonization yield is low, and the shrinkage rate accompanying carbonization is high, so the occurrence of cracks is high and firing is difficult. However, it has the disadvantage that it is difficult to obtain large-sized products or complex-shaped products.

On the other hand, when trying to obtain a carbon material by oxidizing the thermoplastic pitch with oxygen, ozone, sulfur, and various oxidizing agents and removing the thermoplasticity, the thermoplastic pitch is used as a carbon precursor. teeth,
Although products with high carbonization yield and easy graphitization can be obtained,
The diffusion rate of the oxidizing agent into the inside of the pitch is slow, and the shapes that can be made infusible by oxidation are limited to fiber-like, film-like, etc. If the diameter is large or thick, the inside cannot be made infusible, resulting in blisters and cracks. It had some drawbacks.

In view of the above problems, the present inventors have completed the present invention by completely solving these problems as a result of intensive research.

(Means for Solving the Problems) The present invention is based on a thermosetting condensed polycyclic polynuclear aromatic resin previously proposed by the present inventors in Japanese Patent Application No. 60-265983 and Japanese Patent Application No. 61-34761, etc. Based on the knowledge that (COPNA resin) has a high carbonization yield and a small yield during carbonization, it also has a high carbonization yield, small shrinkage during carbonization, and can freely control graphitization. The object is to provide a method for producing a thermosetting carbon precursor, and the above object can be achieved by providing the method for producing a thermosetting carbon precursor.

Next, the present invention will be explained in detail.

That is, the present invention uses petroleum-based materials with a softening point of 120°C or higher,
An aromatic compound containing at least one type of hydroxymethyl group or halomethyl group, which is obtained by hydrogenating at least one type of coal-based pitch to lower the softening point without impairing the carbonization yield. This is a method for producing a carbon precursor made of a thermosetting resin, which is characterized by adding a crosslinking agent mainly consisting of .

In order to obtain a carbon precursor having a higher carbonization yield, it is necessary to obtain a thermosetting resin by crosslinking pitch with the crosslinking agent in the presence of the acid catalyst and having a higher carbonization yield. The present inventors have newly discovered that. However, pitches that generally have a high carbonization yield have a high softening point (in the present invention, the softening point refers to that measured using the ring and ball method). Therefore, in order to uniformly crosslink the pitch with the crosslinking agent, the heating temperature must be at least higher than the softening point of the pitch. However, the present inventors have found that as the heating temperature increases, the reaction rate inevitably increases, making it difficult to control the reaction. Therefore, in the present invention, at least one kind of petroleum-based or coal-based pitch with a softening point of 120°C or higher is used.
The objective is to perform hydrogenation to lower the softening point, lower the heating temperature, and uniformly crosslink the resulting carbon precursor without impairing the carbonization yield. The present inventor has found that by using the pitch as a thermosetting carbon precursor according to the production method of the present invention, the carbonization yield is improved by 15 to 20% by weight compared to the carbonization yield of the mixture itself. They made new discoveries and were able to complete the present invention.

The pitch, hydrogenation, crosslinking agent, and acid catalyst of the present invention will be explained below.

At least one type of petroleum-based or coal-based pitch with a softening point of 120°C or higher has a low carbonization yield.
50% by weight or more, preferably 60% by weight or more,
A material containing small spheres (so-called mesophases) exhibiting optical anisotropy as a component can also be used. In this case, it is preferable to select as the starting material pitch which has a low softening point and a high carbonization yield.

The hydrogenation used in the present invention is a direct hydrogenation method in which hydrogenation is performed using a catalyst in a hydrogen stream at high temperature and high pressure, and aromatic nuclear hydrogenation is performed under high temperature and high pressure.
Hydrogenation method using a hydride in which a Lewis acid such as aluminum chloride is added to a metal hydride such as LiAl hydride, Birch reduction method using liquid ammonia and metallic sodium, tetralin, tetrahydroquinoline, 9,10-dihydroanthracene, and Pitzi fraction. Any known hydrogenation method may be used, including the so-called solvent donor method in which a partially hydrogenated aromatic compound such as a hydrogenated product is used as a hydrogen source and as a solvent for pitch, but the direct hydrogenation method using high pressure gas is preferable. The hydrogenation is carried out using Co-Mo/Mo as a catalyst.
Al ₂ O ₃ , Ni-Mo/Al ₂ O ₃ , NiO, CoO ₃ , Pt, Pd
etc. is used in an amount of 0.5 to 10 parts by weight per 100 parts by weight of pitch, in the presence of the catalyst at a treatment temperature of 250°C to 500°C, preferably 300°C to 400°C, and a pressure of 50 Kg/cm ² to 300 Kg/cm ² .
It is preferably carried out under conditions of 100Kg/cm ² to 200Kg/cm ² .
According to NMR measurements, the pitch after hydrogenation contains naphthenic hydrogen, has a lower aromatic index fa than the raw pitch, and has a higher H/C. Alternatively, a distillation operation may be performed after hydrogenation to remove low molecular weight components and adjust the softening point of the pitch.

Such hydrogenation makes it possible to lower the softening point of pitch to 100° C. or less, and also to control viscosity, graphitizability, and improve the carbonization yield of carbon precursors.

The purpose of hydrogenation in the present invention is to lower the softening point of the pitch, which originally has a high molecular weight, without reducing the carbonization yield. That is, the softening point can be lowered by preventing the fused polycyclic aromatic molecules constituting the partially nuclear hydrogenated pitch from stacking in the plane direction by van der Waals force.
Further, due to such hydrogenation, the planar structure of the condensed polycyclic aromatic molecule only partially becomes three-dimensional, and the molecular weight of the condensed polycyclic aromatic molecule hardly changes. Therefore, the carbonization yield hardly decreases, and the present invention was made with attention to this point.

The crosslinking agent of the present invention is xylylene glycol, xylylene dichloride, xylylene dibromide,
Alternatively, derivatives thereof such as dimethylxylylene glycol, dimethylxylylene dichloride, dimethylxylylene dibromide, etc. can be used.

The acid catalyst of the present invention includes sulfuric acid, phosphoric acid, organic sulfonic acid, carboxylic acid, aluminum chloride, boron fluoride,
Alternatively, any one type or a mixture of two or more types selected from the group consisting of these derivatives can be used.

Next, regarding the amount of the crosslinking agent and the acid catalyst added to the mixture, the crosslinking agent is 40 to 80 parts by weight per 100 parts by weight of the mixture, and the acid catalyst is 1.0 parts by weight per 100 parts by weight of the crosslinking agent and mixture. ~20 parts by weight is a preferred range. Moreover, the temperature range for the heating to convert these into thermosetting resins is preferably 60 to 300°C. By appropriately selecting the heating temperature and time, a thermosetting intermediate reaction product (so-called B-stage resin) having substantially thermoplastic properties can be obtained. The use of stage resins is particularly advantageous. 100 after shaping
By heating to a temperature range of ~400°C, a cured product that is insoluble and infusible during subsequent carbonization can be obtained.

In general, carbon precursors are required to have a high carbonization yield and to be able to control graphitizability depending on the purpose. The inventors of the present invention have applied for a patent application filed in 1983-
No. 28178 provided a method of using COPNA resin as an adhesive for graphite material and carbonizing the graphite material after adhesion, but in this case, the carbonization yield of COPNA resin was 67% by weight and 70% by weight. %, it was found that the adhesive strength obtained was approximately twice as high in the latter case. In this way, the carbonization yield of the carbon precursor is an important factor that determines the properties of the obtained carbon, and improving the carbonization yield also reduces the shrinkage rate and crack generation rate during carbonization. This brings about the advantage that larger sizes can be fired with higher yields and faster heating rates.

On the other hand, by carbonizing conventional thermosetting resins such as phenol or furan resins, only non-graphitizable carbonaceous materials can be obtained. This is a highly gas-impermeable material called glassy carbon. In the present invention, by adding oxidizing agents such as oxygen and sulfur to the pitch after hydrogenation, glassy carbon has a much higher carbonization yield than conventional thermosetting resins such as phenol or furan resins. Not only can a precursor be obtained, but also an easily graphitizable thermosetting carbon precursor can be obtained by using a hydrogenated pitch having a large molecular weight and high aromaticity as a starting material.

In addition, carbon such as artificial graphite, natural graphite, expanded graphite, coke, carbon black, carbon fiber, etc. can be used as an aggregate in the thermosetting carbon precursor of the present invention.
When graphite or a precursor thereof is added and used, the carbonization shrinkage becomes smaller and effects such as no cracking occur even when firing at a faster temperature increase rate are obtained.

(Example) Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 Coal-based pitch with a softening point of 220°C was hydrogenated in the presence of a Ni-Mo catalyst at a temperature of 430°C and an initial hydrogen pressure of 150 kg/cm ² for 1 hour to obtain hydrogenated pitch with a softening point of 80°C. Ta. After adding 40% by weight of p-xylylene glycol to the hydrogenated pitch, 9% by weight of p-toluenesulfonic acid was added to the mixture, and the mixture was reacted at 120° C. for 40 minutes to obtain a B-stage resin. After molding this B-stage resin at a mold temperature of 180℃,
The temperature was raised to 1000°C in a non-oxidizing atmosphere at a rate of 50°C/hr to carbonize. The carbonization yield was 74% by weight, and the linear shrinkage due to carbonization was 10%.

Example 2 A coal-based air blow pit with a softening point of 165°C was heated to
Hydrogenation was carried out at 90°C by the Birch reduction method to obtain hydrogenated pitch with a softening point of 92°C. After adding 45% by weight of p-xylylene dichloride to the hydrogenated pitch, 10% by weight of p-toluenesulfonic acid was added to the mixture and reacted at 130°C for 30 minutes to obtain a B-stage resin. To this B-stage resin, 50% by weight of petroleum raw coke crushed to 10μm or less was added as aggregate, and to this was added 5% by weight of sulfur crushed to 5μm or less. In-die extension molding. The molded body was heated to 1000°C at a heating rate of 20°C/hr in a non-oxidizing atmosphere to carbonize it. This carbonaceous fired body was glassy carbon having gas impermeability of 10 ⁻⁸ cm ² /sec·cmHg to helium gas.

Example 3 Tetralin was added to coal-based pitcher with a softening point of 250°C at 60°C.
After adding % by weight and stirring for 2 hours at a self-generated pressure temperature of 400°C, the 220°C fraction of the pitch was removed to obtain hydrogenated pitch with a softening point of 95°C. After adding 40% by weight of p-xylylene glycol to this hydrogenated pitcher, 6% by weight of p-toluenesulfonic acid was further added to the mixture, and the mixture was reacted at 150°C for 60 minutes.
A B-stage resin was obtained. This B stage resin
After molding at 200℃, in a non-oxidizing atmosphere
The temperature was raised to 1000°C at a rate of 50°C/hr, and carbonization was performed. The carbonization yield was 85% by weight, and the linear shrinkage due to carbonization was 8%.

(Effect of the invention) As explained above, according to the present invention, the softening point is 120
At least one kind of petroleum-based or coal-based pitch is hydrogenated to lower the softening point to the above-mentioned heating temperature, and the resulting carbon precursor is crosslinked uniformly without impairing the carbonization yield. You can force it.

By the production method of the present invention, a thermosetting carbon precursor using the pitch as a starting material is obtained which has a carbonization yield that is 15 to 20% higher by weight than the carbonization yield of the mixture itself, and The precursor has a small shrinkage during carbonization, and when using it to obtain a carbonaceous fired body, it is possible to obtain a large-sized product with a low crack occurrence rate and a higher yield. It has the advantage of being able to be fired at a fast temperature increase rate. Furthermore, the properties of the obtained carbonaceous fired body range from non-graphitizability to easy graphitization, that is, the properties after graphitization range from highly impermeable so-called glassy carbon to electrical conductivity, It has a wide range of properties that graphite has, such as thermal conductivity and machinability, and has the advantage of being freely controllable by selecting starting materials.

These advantages can be expected to make a significant contribution to industry.

Claims (1)

[Claims] 1. After hydrogenating at least one of petroleum-based or coal-based pitches having a softening point of 120°C or higher to lower the softening point, at least one of a hydroxymethyl group or a halomethyl group is added. Adding a crosslinking agent mainly composed of an aromatic compound having two or more groups of
A method for producing a carbon precursor made of a thermosetting resin, which comprises heating to a temperature range of 60 to 300°C in the presence of an acid catalyst. 2. The manufacturing method according to claim 1, wherein the pitch has a carbonization yield of 50% by weight or more. 3. The hydrogenation is carried out in a hydrogen stream under high temperature and pressure,
The manufacturing method according to claim 1, characterized in that the manufacturing method is carried out using a catalyst. 4. The manufacturing method according to claim 1, wherein the hydrogenated pitch has a softening point of 100°C or less. 5. Claim 1, characterized in that the crosslinking agent is one or more selected from the group consisting of xylylene glycol, xylylene dichloride, xylylene dibromide, or derivatives thereof. manufacturing method. 6 The acid catalyst is sulfuric acid, phosphoric acid, organic sulfonic acid,
2. The manufacturing method according to claim 1, wherein the material is one or a mixture of two or more selected from the group consisting of carboxylic acid, aluminum chloride, boron fluoride, or derivatives thereof.