JPH0135767B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a hard carbon precision molded body. Specifically, the present invention provides a hard carbon precision molded body that is dense, homogeneous, has high mechanical strength, and has a precise and complex shape, which can be easily manufactured in small quantities without essentially requiring secondary processing. The present invention relates to a method for manufacturing a hard carbonaceous precision molded body suitable for both multi-product mold production and mass production.

Conventionally, carbon molded products are generally made by using petroleum coke, pitch coke, graphite, carbon black, etc. as raw materials as aggregates, using a viscous material such as petroleum-based or coal-based pitch as a binder, and heating and kneading these. It is manufactured by molding and firing or graphitizing under heat.

Therefore, in order to obtain a dense and highly accurate carbon molded product, the raw material aggregate is pulverized to 10 microns or less, the above-mentioned binder is added to this, and the above procedure is followed, but if the aggregate is pulverized, As you can see, uniform dispersion and kneading with the binder becomes difficult. In particular, when carbon black has an aggregate particle size of several microns or less and has a structure in which the particles aggregate secondary to each other, uniform dispersion with the binder is nearly impossible, and a large amount of solvent must be used or Not only is it extremely complicated and unfavorable from an economic standpoint, as it requires a spray drying process, but also a large amount of vapor from volatile tar components and solvents is generated, contaminating the working environment and being unfavorable from an occupational health standpoint.

In addition, in order to obtain high density and high strength in terms of quality, it is necessary to
After firing at around 1000°C, the material is impregnated under pressure with a viscous component such as a synthetic resin solution, tar, or soft pitch, and fired again. This operation is repeated until the target density is reached.

In order to improve this situation, petroleum pitch, coal tar pitch, etc. are heat treated at a temperature of about 200 to 500 degrees Celsius to remove low volatile matter, and then pulverized to form a powder with an average particle size of about 100 μm. A method was proposed in which the material is heated and pressed and then fired without adding a binder.

However, even with this method, delicate temperature and time management is required during the heat treatment process of pituti, which not only causes great difficulty in the subsequent crushing work, but also causes the crushed particles to heat-fuse again. There were drawbacks such as clumping and significantly deteriorating grinding efficiency.

Furthermore, when the heat treatment temperature becomes high, the carbon yield and stability against deformation improve; however, the material has poor thermoplasticity and does not flow, making complex and precise molding using molds extremely difficult. On the other hand, the powder has poor cohesive strength and the resulting compact does not have sufficient strength, making it inconvenient to handle.On the other hand, if the heat treatment temperature is low, residual volatile components tend to form into agglomerates during re-grinding, resulting in poor structure of the fired product. It was difficult to obtain a precision molded product due to roughness and large deformation.

Recently, progress has been made in the development of new carbon materials that use mesophace microbeads and mesophace-coated semi-formed coke, and use a different production method in which they are directly molded and then fired.
In addition to requiring many processes and expenses to make each material into a molding material, the shaping method is difficult, and there is no easy processing method like plastics or general metal materials, so it is usually produced in large blocks and the final In order to make a product, carbon black must undergo secondary processing such as cutting, drilling, and threading using processing machines used for metal materials, depending on the purpose. Since the grinding mechanism is mainly used for crushing, chips are scattered, reducing accuracy and increasing tool wear. Furthermore, stress acts on the surface of the workpiece, creating countless scratches, which causes a significant decrease in the mechanical strength of carbon products, which are inherently brittle. However, in the case of general carbon materials (soft carbon), it was possible to use the above secondary processing method, but in the case of hard carbon materials (hard carbon), the shore hardness reached 100 to 120, making it hard and brittle. Therefore, secondary precision machining was completely difficult.

The purpose of the present invention is to easily and quickly produce a hard carbonaceous precision molded body having a precise and complex shape, which is dense, homogeneous, has strong mechanical strength, and is free from cavities and cracks, essentially without the need for secondary processing. It is an object of the present invention to provide a method for manufacturing a hard carbonaceous precision molded body, which is suitable for both small-scale production of a wide variety of products and mass production at the same time.

In order to achieve this objective, the inventors of the present application took into consideration the above circumstances, and developed a method that has excellent formability at room temperature and does not require difficult pretreatment during carbonization, and maintains its shape accurately in the final stage. We are conducting research to obtain a molding composition that can yield high-density, high-strength carbon molded products that are suitable for small-lot, high-mix production as well as mass production without the need for subsequent processing. During manufacturing, a high degree of mechanical energy is applied to a homogeneously dispersed mixture of finely divided carbonaceous aggregate and polymeric resin binder. Based on this knowledge, we realized that products that can be made infusible by simple air oxidation and fired are homogeneous, have high mechanical strength, and can achieve the desired dimensional accuracy.
Furthermore, as a result of intensive research, it was found that the fine carbon powder of the present invention can be used as a binder with a thermosetting resin monomer, prepolymer or low One type of polymer or a mixture of two or more types of polymers is uniformly dispersed, and mechanical energy is applied to induce a mechanochemical phenomenon to uniformly distribute the binder evenly onto the surface of the primary particles of the fine powder. After obtaining a chemically strongly bonded molding paste composition, injecting the composition into a casting mold or injecting it into a molding mold, taking it out after polymerization and solidification, and subjecting it to infusibility treatment. The inventors have now invented a method for manufacturing a hard carbonaceous precision molded body that essentially does not require secondary processing, which is characterized by firing.

That is, as a binder, one or more types of thermosetting resin monomers, prepolymers, and low polymers that exhibit a high carbonaceous residue yield after firing and that can be relatively easily thermally polycondensed are selected. In addition, finely divided carbon, i.e., graphite with an average particle size of 100 μm or less, is added as an aggregate.
By adding carbon black, coke powder, etc., and applying a high degree of mechanical energy in the coexistence of fine carbon powder (adding a polymerization catalyst as necessary), the crystal lattice is distorted, disturbed, and eliminated by the structural destruction of the aggregate powder. The above-mentioned binder material undergoes mechanochemical phenomena by utilizing regularization, generation of lattice defects and active points on the surface, generation of localized high temperature and high pressure conditions, effects of exoelectrons, and generation of fresh cross sections with high potential fields. A highly fluid pasty composition containing finely dispersed particles that are physicochemically highly bonded is obtained by this method, and this is used as a composition for producing carbon products.

In the present invention, as described above, a paste composition with high fluidity is used, so it is poured into a casting mold,
Alternatively, the molded product that is injected into a mold and taken out from the mold after polymerization and solidification can be traced accurately to the shape of the mold, regardless of the complexity of the shape, the thickness of the wall, etc. In addition, during carbonization, the entire composition is fixed by the aggregate in which the binder is mechanochemically bonded to the primary particles, and furthermore, during carbonization, it exhibits a designed uniform shrinkage rate. It is possible to obtain a thick, complex, and precise hard carbon precision molded body that was previously unobtainable.

Examples of thermosetting resin monomers, prepolymers, or low polymers used in the present invention include divinylbenzene, methyl vinyl ketone, phenolic resin, furan resin, bismaleimide triazine resin, diphenyl oxide, epoxy resin, and unsaturated polyester resin. However, furan resin, phenol resin, and bismaleimide triazine resin are suitable from the viewpoint of ease of handling and moldability.

In the present invention, the carbon fine powder is natural scaly graphite,
Use one or more types selected from natural earth graphite, artificial graphite, carbon black for rubber, carbon black for colors, lamp black, various resin carbides, coke powder, etc. with an average particle size of 100 μm or less.
If the powder has an average particle size of 100 μm or more, the surface of the molded product will be rough during molding, and the mechanical strength after firing will be low, making it impossible to obtain a good hard carbon precision molded product.
The blending amount of carbon fine powder is appropriately selected in the range of 5 to 70 parts by weight based on 100 parts by weight of the blended composition. However, if the blending amount is less than 5 parts by weight, the carbon fine powder becomes a binder due to mechanochemical phenomenon. The absolute amount of finely dispersed particles that are highly physicochemically combined in the powder is insufficient, making it impossible to obtain a good hard carbon precision molded body, resulting in blistering, cracking, and cracking during the firing process, resulting in damage. Resulting in. In addition, if the blending amount exceeds 70 parts by weight, the paste composition will have poor fluidity and will be difficult to form well, and at the same time, it will be difficult to remove air that is mixed in during paste production. As such, you will not get a good product.

In the method of the present invention, first, 30 to 90 parts by weight of a thermosetting resin monomer, prepolymer, or low polymer and 70 to 5 parts by weight of carbon fine powder are uniformly mixed in a blender. Using a kneading machine with shearing force, such as a mixing roll, a Banbury mixer, or a rotary ball mill, a paste containing finely divided carbon particles in which the binder material is physicochemically highly bonded by a mechanochemical phenomenon is produced. Adjust. At this time, if necessary, a polymerization catalyst or lignin, violanthrone, naphtha cracking pitch, vinyl chloride pitch, or coal tar pitch, which can be mixed with the binder component and exhibits a high carbon residue yield after calcination, may be added to the binder. Even if the binder component is solid at room temperature or liquid at room temperature, heating may be applied during kneading to further increase fluidity and kneadability with fine carbon powder. Some solvents or monomers, prepolymers, or plasticizers may be added.
The viscosity of the molding paste depends on the precision of the casting mold or injection mold, but it requires fluidity of 100 poise or less at 100°C, preferably 20°C poise or less at 100°C. The viscosity of the paste can be adjusted by adjusting the type and amount of the binder, the type and amount of polymerization catalyst, the type and amount of carbon fine powder, the temperature and time during kneading, and the amount of solvent or plasticizer added. Since the adjustment can be carried out freely and easily, it is possible to obtain a paste having a viscosity as required.

Next, the molding paste composition is injected into a casting mold or injected into a molding die to solidify the thermosetting resin as a binder, and then taken out to form a shaped product.
At this time, in order to quickly solidify the thermosetting resin, a polymerization catalyst for the resin may be added to the paste composition in advance, or the casting mold or injection mold may be heated as necessary. will be adopted. In order to uniformly inject or inject the paste-like composition into a mold, the paste-like composition may be heated to reduce its agglomeration.
As the mold material for casting, metal, glass, plaster, wax, wood, rubber, agar, synthetic resin, etc. are appropriately selected depending on the purpose. The casting method is a suitable method for producing a wide variety of molds in small quantities because casting molds can be manufactured easily and inexpensively. The injection molding method requires expensive injection molding machines and molds, but it can shorten the cycle from injection to removal.
It is highly productive and suitable for forming in large quantities at low cost. In particular, the LIM method (Liquid Injection)
Molding) is the most suitable means for the method of the present invention.

The excipients taken out of the mold are subjected to infusibility treatment in a heating oven at 50 to 300°C, then placed in a carbonization furnace and gradually heated from room temperature in an inert atmosphere such as nitrogen or argon. The temperature is raised to 800° C. or higher, preferably 1000° C. or higher to carbonize the product, and after cooling, a hard carbon precision molded product is obtained.

Next, the present invention will be specifically explained using examples.

Example 1 After uniformly mixing 80 parts by weight of furan (Hitafuran VF302 manufactured by Hitachi Chemical Co., Ltd.) and 20 parts by weight of natural scale graphite (Nippon Graphite CSP Co., Ltd.) in a Henschel mixer,
Using three rolls heated to ℃, knead until the binder resin component is homogeneously mixed with graphite powder by mechanochemical phenomenon, the binder resin component starts to polymerize, and the whole becomes slightly thickened. Collect it there. The paste recovered had a viscosity of 20 poise at 25°C.

On the other hand, silicone rubber (manufactured by Toshiba Silicone Corporation)
A casting mold was manufactured using M5 x 0.8 hexagonal bolt specified in JISB-1180 and hexagonal nut M5 x 0.8 specified in JisB-1181 using M5 x 0.8 hexagonal bolt specified in JISB-1180. To the prepared paste composition,
Add 0.1 part by weight of a curing agent for furan resin (A3 curing agent manufactured by Hitachi Chemical Co., Ltd.), stir, degassing, and heat to 40°C to increase fluidity. Pour into both silicone rubber casting molds prepared earlier, solidify in an air oven at 70°C, then remove from the mold, and the dimensions and shape are JisB-1180.
M5 x 0.8 hexagon bolt and JisB specified in
An M5 x 0.8 hexagonal nut specified by -1181 was obtained. Next, the excipient was placed in an oven and the temperature was gradually raised from room temperature, and after 6 hours, the temperature was raised to 180°C, and the mixture was stored at the same temperature for 3 hours to perform an infusibility treatment. After that, 20℃/h up to 500℃ in nitrogen gas atmosphere, and 20℃/h up to 1000℃.
The temperature was raised at 100° C./h, carbonization treatment was performed, and a product was obtained after cooling.

Although shrinkage was observed in the resulting product due to firing, it maintained the shape and dimensions of the M4 x 0.7 hex bolt specified by JisB-1180 and the M4 x 0.7 hexagon nut specified by JisB-1181 with good accuracy. The tensile strength of the hexagonal bolt is 20Kg/mm ² Shore hardness 120, and the hexagonal nut has a compressive strength of 40Kg/mm ² and Shore hardness 120, making it a hard carbon hexagon with excellent mechanical strength that does not require secondary processing. It was a bolt and a hexagonal nut.

Example 2 75 parts by weight of bismaleimide triazine resin (BT-2100 manufactured by Mitsubishi Gas Chemical Co., Ltd.) and 25 parts by weight of natural earthy graphite powder (Nippon Graphite ASP-E Co., Ltd.) were charged into a Banbury mixer, and the mixture was poured into a tank. While keeping the temperature at 100℃,
After kneading for 20 minutes, a paste containing carbon particles in which a resin component and graphite powder were firmly bonded was obtained by a mechanochemical phenomenon. The recovered paste was solid at room temperature, but had a viscosity of 5 poise at 100°C. Next, an organic peroxide and an organic metal salt were added so that the prepared composition would harden in 10 minutes at 180°C, and the composition was heated to 100°C using a LIM injection molding machine equipped with a turntable. The mixture was injected into a mold maintained at a temperature of 180° C. and taken out after 10 minutes to obtain a pot-shaped molded product with a wall thickness of 2 mm, a height of 100 mm, an outer diameter at the upper end of 60 mm, and an outer diameter at the lower end of 50 mm. Next, the molded product was placed in an oven and the temperature was raised from room temperature to 180℃ after 1 hour.
℃, and after being kept at the same temperature for 3 hours and subjected to infusibility treatment, it can be heated up to 500℃ in a nitrogen gas atmosphere.
The temperature was raised at a rate of 100°C/h up to 1000°C, carbonization treatment was performed, and a product was obtained after cooling. Although shrinkage was observed in the resulting product due to firing, it was completely similar in shape to the product before carbonization treatment, with highly accurate dimensions of wall thickness 1.2 mm, height 60 mm, top outer diameter 36 mm, and bottom outer diameter 30 mm. It was a hard carbon tip-shaped molded product with

The resulting product has smooth skin and impermeability of 5x
A small-shaped molded product made of hard carbon that is large at 10 ^-9 cm ² /s (He, △P = 1 atm) and has excellent mechanical strength with a shore hardness of 110 and a compressive strength of 35 Kg/mm ² that does not require secondary processing. It was hot.

Claims (1)

[Scope of Claims] 1. A thermosetting resin monomer, prepolymer, or low polymer that is a substance that exhibits a high carbon residue yield after sintering and is relatively easily thermally polymerizable as a binder in carbon fine powder. A species or a mixture of two or more species is uniformly dispersed, and mechanical energy is applied to induce a mechanochemical phenomenon to uniformly and physicochemically harden the binder to the surface of the primary particles of the fine powder. A combined molding paste composition is obtained, the composition is injected into a casting mold or injected into a molding mold, polymerized and solidified, then taken out, subjected to infusibility treatment, and then fired. A method for manufacturing a hard carbon precision molded body, characterized by: 2. The molding paste composition has a viscosity of 100°C.
The manufacturing method of item 1, wherein the manufacturing method is 100 poise or less.