JPH04240164A - Adhesive for carbon and graphitic member and pretreating agent and joining method thereof - Google Patents

Abstract

PURPOSE:To improve the joint strength and thermal impact resistance of a carbonaceous adhesive layer by uniformly dispersing a specific org. binder into carbon powder and kneading this mixture under high shearing force. CONSTITUTION:The adhesive for carbon and graphitic members is obtd. by compounding 1 to 80 pts.wt. carbon powder having <=50mum average grain size and 99 to 20 pts.wt. org. binder contg. at least one kind selected from the monomer, proploymer and low polymer of thermosetting resins which are materials exhibiting a high carbon residue yield after baking and can be relatively easily polymerized, uniformly mixing and dispersing the mixture, then kneading the mixture under the high shearing force. The pretreating agent for carbon and graphitic members is obtd. by compounding 5 to 200 pts.wt. solvent and/or a plasticizer which codissolves the above-mentioned resin components with 100 pts.wt. adhesive and kneading the mixture under high shearing force. The above-mentioned pretreating agent is applied on adherends consisting of the carbon and graphite and is dried by heating; thereafter, the adherends are bonded with the above-mentioned adhesive and are heated to >=500 deg.C in an inert atmosphere to carbonize the pretreating agent and the adhesive and to join the adherends.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides carbon, graphite electrodes,
The present invention relates to adhesives and pretreatment agents for members for various jigs such as resistance heating elements, heat insulating materials, crucibles, and containers, and methods for joining the same. Specifically, the carbon adhesive layer after carbonization has excellent bonding strength and thermal shock resistance, and it is also suitable for complex-shaped objects that require a large amount of material loss and many processing steps with conventional cutting.
The present invention relates to an adhesive and a pretreatment agent for carbon and graphite members, and a method for joining the same, which can provide complex-shaped bodies that cannot be obtained by conventional cutting processes.

0002

[Prior Art] Conventionally, various jigs such as electrodes, resistance heating elements, heat insulating materials, crucibles, containers, etc. made of carbon or graphite are generally made from blocks made of carbon or graphite by cutting them into desired shapes. A product with the shape of is obtained. Therefore, products with large dimensions must be machined from large blocks, and products with complex shapes not only generate a large amount of material loss in the processing process but also require a large number of processing steps. Therefore, it has disadvantages such as being economically extremely expensive.

0003

OBJECTS OF THE INVENTION It is an object of the present invention to bond carbon and graphite members firmly with carbon, to have excellent bonding strength of the carbon adhesive layer after carbonization, and to have excellent thermal shock resistance. Conventional cutting produces a large amount of material loss, and it is possible to economically and inexpensively provide complex-shaped objects that require multiple machining processes, or complex-shaped objects that cannot be obtained by conventional cutting. An object of the present invention is to provide an adhesive and a pretreatment agent for carbon and graphite members, and a method for joining the same.

0004

[Means for Solving the Problems] The present invention provides: (1) Adding to carbon powder, as a binder, a thermosetting resin monomer, which is a substance that shows a high carbon residue yield after firing, and which can be relatively easily polymerized. Carbon graphite obtained by blending an organic binder containing at least one selected from the group consisting of polymers and low polymers, and thoroughly kneading the uniformly mixed and dispersed caking composition by applying high shearing force. Adhesive for parts,

0005] ■
Carbon powder, as a binder, at least one substance selected from the group consisting of relatively easily polymerizable thermosetting resin monomers, prepolymers, and low polymers, which exhibit a high carbon residue yield after firing. A pre-treatment agent for carbon and graphite members, which is prepared by blending an organic binder containing the above resin component with a solvent and/or plasticizer that co-dissolves the resin component, and thoroughly kneading the mixture by applying high shearing force. and

[0006] ■ The pretreatment agent described in the previous section (■) is applied to an adherend made of carbon or graphite, and after heating and drying, it is bonded using the adhesive described in the previous section (■), and then, in an inert atmosphere, This is a method for joining carbon and graphite members, characterized by carbonizing a pretreatment agent and an adhesive. Preferably, the carbonization is carried out at a temperature of 500°C or higher.

[0007] The carbon powder described in (1) or (2) above is as follows:
At least one selected from the group consisting of natural graphite, artificial graphite, quiche graphite, carbon black, and coke powder is preferred.

[0008] Further, the thermosetting resin described in (1) or (2) above includes furan-based resins such as furfuryl alcohol resin, furfuryl alcohol/furfural co-condensed resin, and furfural/phenol co-condensed resin; resol-based resins; At least one selected from the group consisting of monomers and/or initial condensates of phenolic resins such as novolak resins, xylene resins, and toluene resins is preferred.

The advantage of the excellent bonding strength of the carbonized adhesive layer, which is a feature of the present invention, is due to the following reason. In other words, by using a thermosetting resin that has a high carbon residue yield after carbonization and a low firing shrinkage rate as the binding material, and adding carbon powder to this, it is possible to further reduce the firing shrinkage rate. Therefore, the adherend and the adhesive layer are firmly bonded, and high bonding strength can be obtained after carbonization. In addition, by applying a pretreatment agent adjusted to a relatively low viscosity and having a high carbon residue yield onto the surface of the adherend in advance, the pretreatment agent penetrates into the pores that exist in large numbers on the surface of the adherend. By increasing the physical bond with the adherend and increasing the affinity between the adherend and the adhesive, it is possible to significantly improve the bonding strength after carbonization. In addition, in order to increase chemical bonding with the adherend, a known surface oxidation method such as nitric acid oxidation, electrolytic oxidation, or gas phase oxidation is applied to the surface of the adherend in advance to remove carbonyl groups, carboxyl groups, and phenol groups. By introducing a surface functional group such as a functional hydroxyl group or an ether structure, it is possible to further increase the bonding strength.

Focusing on the fact that a carbon material has an extremely wide range of intermediate structures from amorphous carbon to completely graphite crystal, (1) select any carbon powder according to the purpose; and change the blending ratio with the thermosetting resin component. (2) The carbonization temperature of the adhesive layer should be appropriately selected within the temperature range of 500 to 3000°C. By arbitrarily controlling methods (1) and (2), the coefficient of thermal expansion of the adhesive layer can be adjusted to 2.
It became possible to control the temperature within the range of 0 to 7.0×10 −6 /°C. As a result, by controlling the thermal expansion coefficient of the carbonaceous adhesive layer depending on the material of the carbon or graphite member, it became possible to obtain excellent thermal shock resistance of the carbonaceous adhesive layer after carbonization.

[0011] Next, the adhesive and pretreatment agent for carbon and graphite members of the present invention and the bonding method thereof will be explained in detail. As the carbon powder, one or more types are selected from carbon powders such as natural graphite, artificial graphite, carbon black, and coke powder, and the average particle size is 50 μm or less, preferably 10 μm or less.
Carbon powder of micrometer or less. The amount of carbon powder is 1 to 8 parts by weight per 99 to 20 parts by weight of the thermosetting resin binder component.
0 parts by weight, preferably thermosetting resin binder component 45-5
5 to 50 parts by weight are added to 0 parts by weight to make the total weight 100 parts by weight.

[0012] As the binder, one type or a mixture of two or more types of thermosetting resin monomers, prepolymers, or low polymers that are relatively easily polymerizable and exhibit a high carbon residue yield after firing are used. Use. Actually, furfuryl alcohol resin, furfuryl alcohol/furfural co-condensation resin,
One or more types of thermosetting resins such as furan-based resins such as furfural/phenol cocondensation resins; phenolic resins such as resol-based and novolac-based resins; xylene resins; and toluene resins are selected. A mixture of carbon powder and a binder will be referred to as a binder composition.

[0013] This caking composition is uniformly dispersed using a mixer, etc., and then mechanical energy such as shearing force is applied to it using a two-roll, three-roll, ball mill, pressure kneader, etc. An adhesive is obtained in which an organic substance is physicochemically bonded to the surface of the primary particles of carbon powder by inducing a mechanochemical phenomenon.

The amount of the solvent and/or plasticizer that co-dissolves the thermosetting resin component to be added to the pretreatment agent is determined based on 100 parts by weight of the caking composition consisting of the carbon powder and the thermosetting resin component. , added in an amount of 5 to 200 parts by weight. A mixture of a caking composition and a solvent is uniformly dispersed using a mixer, etc., and mechanical energy such as shearing force is applied using a two-roll, three-roll, ball mill, etc.
A mechanochemical phenomenon is induced to physicochemically bond an organic substance to the surface of the primary particles of carbon powder, and a pretreatment agent whose viscosity is adjusted to be low is obtained.

Next, a method of bonding carbon and graphite members using the pretreatment agent and adhesive obtained by the above operations will be explained. First, a pretreatment agent is applied to the surface of an adherend by a commonly used method such as brush coating or spray coating, and the pretreatment agent is solidified by drying and three-dimensional crosslinking. At this time, a curing agent may be added to the pretreatment agent if necessary. Further, for the purpose of enhancing the chemical bond with the adherend, a known surface oxidation method such as nitric acid oxidation, electrolytic oxidation, or gas phase oxidation may be applied to the surface of the adherend in advance. Next, an adhesive is applied to the adherend material coated with the pre-treatment agent, the adhesive is bonded, and the adhesive is solidified by drying and three-dimensional crosslinking to complete the bonding. At this time, a curing agent may be added to the adhesive if necessary. Further, in order to obtain high bonding strength, it is preferable to press the bonded portion with a jig.

[0016] Next, this is subjected to air oxidation, if necessary.
Carbon precursor treatment such as ozone oxidation or strong acid treatment is performed, and the temperature is raised from room temperature in an inert atmosphere such as nitrogen or argon gas to 500°C or higher, preferably 700°C or higher to form a pretreatment agent and adhesive. Carbonization treatment is performed, and after cooling, it is taken out and used as a product. The upper limit of firing can also be adjusted as necessary.
The temperature may be raised to about 3000°C.

[0017]

[Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited by the Examples. (Example 1) Initial condensate of furfuryl alcohol/furfural resin (Q1001 manufactured by Takeda Pharmaceutical Co., Ltd.)
After blending 70% by weight and 30% by weight of natural scaly graphite (average particle size 1 μm) in a Warner mixer and uniformly dispersing it, further dispersion was performed using a water-cooled three-roll for ink kneading. An adhesive was obtained. Next, add 100% THF (tetrahydrofuran) to the above adhesive composition.
After adding % by weight and uniformly dispersing it with a Warner mixer,
A pretreatment agent was obtained by performing a more advanced dispersion using a water-cooled three-roll ink kneading roll.

Next, using an artificial graphite material (GE-102 manufactured by Tohoku Kyowa Carbon Co., Ltd.) as an adherend, a pretreatment agent was applied with a brush to the surface of the test piece whose adherend surface had been cleaned with alcohol. This is then held in an air bath at 80° C. for 2 hours to dry the pretreatment agent and complete the pretreatment operation. Next, 3% by weight of p-toluenesulfonic acid 50% methanol solution was added as a curing agent to 100% by weight of the adhesive,
The mixture is sufficiently stirred at room temperature using a high-speed homomixer, applied to the surface to be adhered, and the adherend material is firmly crimped with a jig to complete the joining operation. Next, put this in an air oven for 10 minutes.
After performing carbon precursor treatment by holding at 0°C for 10 hours and further at 180°C for 5 hours, the fixing jig was removed and heated at a rate of 15°C/hour to 500°C in a nitrogen gas atmosphere furnace.
Heating was performed from 0°C to 1000°C at a temperature increase rate of 30°C/hour. Subsequently, the pretreatment agent and adhesive were carbonized by holding at 1000° C. for 3 hours, and then allowed to cool naturally to complete the firing.

(Example 2) The sample of Example 1 was subjected to nitric acid oxidation treatment, and all other conditions were the same as in Example 1 to obtain a test piece.

(Comparative Example) A test piece was obtained by applying no pretreatment agent to the sample of Example 1 and performing all other conditions in the same manner as in Example 1.

Table 1 shows the results of adhesive bending fracture tests conducted on the test pieces of Example 1, Example 2, and Comparative Example. For comparison, the results of a bending fracture test using only graphite material without bonding are also listed.

[Table 1]

[0022]

[Effects of the Invention] Carbon material molded products manufactured using the adhesive and pretreatment agent for carbon and graphite members and the bonding method thereof according to the present invention have high bonding strength and excellent thermal shock resistance. Conventional cutting processes result in a large amount of material loss, and complex-shaped objects that require multiple machining processes, as well as complex-shaped objects that cannot be obtained using conventional cutting processes, can be produced economically and at low cost. , the present invention is extremely useful and beneficial.

Claims (8)

[Claims] Claim 1: A material selected from the group consisting of monomers, prepolymers, and low polymers of thermosetting resins that exhibit a high carbon residue yield after firing and that can be relatively easily polymerized, as a binder in carbon powder. An adhesive for carbon graphite members, which is prepared by blending an organic binder containing at least one selected organic binder, uniformly mixing and dispersing the binder composition, and applying high shearing force to sufficiently knead the binder composition. 2. A material selected from the group consisting of monomers, prepolymers, and low polymers of thermosetting resins that exhibit a high carbon residue yield after firing and that can be relatively easily polymerized, as a binder in carbon powder. Carbon or graphite made by blending an organic binder containing at least one of the selected organic binders, adding a solvent and/or plasticizer that co-dissolves the resin component, and thoroughly kneading the mixture by applying high shearing force. Pre-treatment agent for parts. 3. The pretreatment agent according to claim 2 is applied to an adherend made of carbon or graphite, and after heating and drying, the adhesive is bonded using the adhesive according to claim 1, and then the adhesive is heated in an inert atmosphere. A method for joining carbon and graphite members, characterized by carbonizing a pretreatment agent and an adhesive. 4. The adhesive for carbon and graphite members according to claim 1, wherein the carbon powder is at least one selected from the group consisting of natural graphite, artificial graphite, Quiche graphite, carbon black, and coke powder. 5. The pretreatment agent for carbon and graphite members according to claim 2, wherein the carbon powder is at least one selected from the group consisting of natural graphite, artificial graphite, quiche graphite, carbon black, and coke powder. 6. The thermosetting resin is a furan resin such as a furfuryl alcohol resin, a furfuryl alcohol/furfural cocondensation resin, or a furfural/phenol cocondensation resin; a phenolic resin such as a resol type or a novolac type; and xylene. The adhesive for carbon and graphite members according to claim 1, which is at least one selected from the group consisting of monomers and/or initial condensates of resin; toluene resin; 7. The thermosetting resin is a furan resin such as a furfuryl alcohol resin, a furfuryl alcohol/furfural cocondensation resin, or a furfural/phenol cocondensation resin; a phenolic resin such as a resol type or a novolac type; and xylene. The pretreatment agent for carbon and graphite members according to claim 2, which is at least one selected from the group consisting of monomers and/or initial condensates of resin; toluene resin; 8. The method for joining carbon and graphite members according to claim 3, wherein the carbonization is performed at a temperature of 500° C. or higher.