JPS635348B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing impermeable carbon sheets. Specifically, the present invention relates to a method for easily producing a uniform impermeable carbon thin plate having a low air permeability, high strength, high elasticity, and high hardness, and having a thickness of several tens of microns to several mm. Such carbon plates can be applied to packings and gaskets, and can be used to reduce the weight of electrodes and shielding plates for chemical plants, etc., and although attempts have been made to manufacture them using various methods, the methods described above have not yet been achieved. A carbon thin plate that satisfies the conditions has not been obtained. for example,
Impermeable graphite is usually made by impregnating a carbon material with phenolic resin or furan resin, etc. and then hardening it, or by impregnating and curing it and then re-baking it, or by repeating impregnation, curing, and firing, but it has a low air permeability. (K = 10 ^-8 cm ² /s), has more than twice the strength of the base material, and has excellent corrosion resistance, but not only is the manufacturing process complicated, but it is limited to thick products due to the manufacturing method. It has the drawback that weight reduction is almost impossible. That is, carbon materials are usually manufactured in the form of blocks, and cutting them into thin plates is necessary, but it is extremely difficult to cut them to a thickness of 1 mm or less, and the thinner limit is several mm. Even if it were possible to cut the material, it would be extremely difficult to process it after impregnating it with resin to prevent cracks, and even if it were to be cut into thin sheets after being made impermeable, the hardness of the carbon material has increased dramatically, making it expensive. Since a cutter must be used and advanced cutting techniques are required, even if thin plates could be manufactured in this way, the cost would be extremely high. An example of successful thinning of carbon products is sheet-shaped flexible graphite.
This sheet-like graphite is made by acid-treating natural graphite, heating it to form expanded graphite, and then rolling it. It can be made as thin as several tens of microns, making it lightweight, and has an air permeability of 2 x 10 ^- It is as small as ⁴ cm ² /s. However, the bending strength is equal to zero and has the disadvantage that it can only be used at locations where no bending stress acts. Furthermore, since a large amount of strong acid is used in the manufacturing process, sufficient attention must be paid to the corrosion resistance of the equipment, wastewater treatment, etc., which inevitably leads to higher costs. on the other hand,
It is as impermeable as glass (K=10 ^-10 ~
10 ⁻¹² cm ² /s), is isotropic, has extremely high mechanical strength, and has an extremely small surface area. This glassy carbon is made from thermosetting synthetic resins such as furan resins and phenolic resins, and by adding an appropriate curing agent to this, it is cured for a long period of 1 to 6 weeks at room temperature or a slightly higher temperature. It is obtained by carbonizing at a slow heating rate to prevent cracking due to the protrusion of volatile components generated by thermal decomposition. As described above, the conventional production of glassy carbon not only takes a long time to carbonize, but also makes it extremely difficult to obtain thin plates from the production process, and the hardness is extremely high, making it impossible to cut thin plates from blocks. This is more difficult than with permeated graphite. The present inventors first mixed and kneaded chlorinated vinyl chloride resin and/or vinyl chloride resin with furan resin, molded the obtained kneaded product into a film or sheet shape, and added carbon precursor to the molded product. After the treatment, we came up with the idea of firing in an inert atmosphere.
Invented a method for manufacturing glassy carbon thin plates and applied for a patent. (Special application No. 57-128967). However, with this method, the tensile strength and tear strength of the film or sheet produced by molding the kneaded material are insufficient, care must be taken in handling, and carbon precursor treatment and sintering treatment are required. Even in the process, it had drawbacks such as lack of impact resistance and easy cracking and breakage. Therefore, the object of the present invention is to provide a uniform impermeable carbon thin plate having a thickness of several tens of microns to several millimeters, which does not have such drawbacks, has low permeability, high strength, high elasticity, and high hardness. It is an object of the present invention to provide a manufacturing method that is extremely easy and inexpensive. As a result of intensive research to achieve this objective, the inventors of the present application have found that the addition of graphite powder improves molding stability.
We discovered that this contributes to a significant increase in the dimensional stability and mechanical strength of carbon thin sheets after firing, and we have developed a method of mixing and kneading chlorinated vinyl chloride resin and/or vinyl chloride resin with furan resin and graphite powder. Achieved a method for producing an impermeable carbon thin plate, which consists of forming the obtained kneaded material into a film or sheet shape, subjecting the obtained molded product to a carbon precursor treatment, and then firing it in an inert atmosphere. However, we succeeded in eliminating the above-mentioned drawbacks. The chlorinated vinyl chloride resin used in the present invention is
It is a polymer having a mixed composition of ( _-CH2 -CHCl)- and (-CHCl-CHCl)- obtained by post-chlorinating vinyl chloride resin. (CH ₂ −CHCl)− and (−
There is no particular restriction on the ratio of CHCl−CHCl)−, but
A chlorinated vinyl chloride resin having a molar ratio of 56:44 to 19:81, that is, a chlorine content of 64 to 70% by weight, has good compatibility with the furan resin. The degree of polymerization is also not particularly limited, but a degree of polymerization of 500 to 2000 is preferred. If it is less than 500, when the kneaded product with the furan resin is molded into a film or sheet, there will be a drawback that the tear resistance will be low and it will easily tear. 2000
If it exceeds the above range, the mixture with the furan resin will become too sticky, making it difficult to process it into a smooth film or sheet. Vinyl chloride resins are broadly classified into compounds and pastes depending on the polymerization method, but compounds are preferable from the standpoint of kneadability with furan resins. There are also straight polymers and resins copolymerized with acrylic esters, ethylene vinyl acetate, etc. However, since the carbon yield of copolymerized resins is generally low, copolymer resins are obtained by carbonization. This is not preferable because the air permeability of the thin plate increases and the strength also decreases. The degree of polymerization is not particularly limited as in the case of chlorinated vinyl chloride resin, but it is preferably between 500 and 2000. If it is less than 500, the green strength of the molded film will be small and difficult to handle, and if it is more than 2000, it will be difficult to mold it to a uniform thickness. becomes difficult. The chlorinated vinyl chloride resin and the vinyl chloride resin are kneaded with the furan resin either alone or as a blend of the two depending on the purpose. moreover,
Two or more resins having different degrees of polymerization may be used as friends. Furan resins to be kneaded with the resin include furfuryl alcohol resin, furfuryl alcohol-furfural copolymer resin, furfuryl alcohol-phenol cocondensation resin, furfuryl alcohol-ketone cocondensation resin, etc. Of course, a mixture of them can also be used. Further, the graphite powder used in the present invention may be either natural graphite or artificial graphite, but in order to increase the mechanical strength when the kneaded mixture of the blended composition is molded into a film or sheet shape, a carbon precursor may be used. In order to improve impact resistance during chemical treatment and subsequent firing treatment,
Scale-like graphite with developed crystals is preferable to amorphous earth-like graphite. The particle size of the powder to be used ranges from 0.5 to 150 μm in average particle size, depending on the thickness of the intended planar object, but if it is finer than 0.5 μm, it will have poor reinforcing effect and will be difficult to degas. If it is 150 μm or more, it is difficult to assemble as a composite, the surface of the molded product becomes rough, and the physical properties are deteriorated, which is not preferable. The amount of graphite powder added is preferably 2 to 50% by weight of the blended composition. If the amount is less than 2% by weight, there is almost no reinforcing effect, and if it is more than 50% by weight, the ratio of the binder becomes too small. This is not preferable because mechanical strength decreases, degassing becomes difficult, and impermeability also decreases. In the method of the present invention, first, a chlorinated vinyl chloride resin, a vinyl chloride resin, or a mixture of both is used.
10 to 88 parts by weight, 5 to 78 parts by weight of furan resin, and 2 to 50 parts by weight of graphite powder are uniformly mixed using a mixer such as a Henschel mixer. Next, this mixed compounded composition is applied to a pressure kneader with two rolls, three rolls,
The mixture is kneaded under heat using a kneader with high shear force such as Konida. When the blended composition is kneaded and heated, it becomes a sticky viscoelastic body, but chlorinated vinyl chloride resin and vinyl chloride resin deteriorate rapidly when the temperature exceeds 200°C, releasing hydrogen chloride gas, and this chloride Since hydrogen gas acts as a curing agent for the furan resin, it is best not to heat it to over 200°C for a long period of time during kneading. In addition, a conventional stabilizer may be appropriately added to the chlorinated vinyl chloride resin or vinyl chloride resin in order to prevent thermal deterioration. Furthermore, in order to effectively and quickly knead these vinyl resins with furan resin and graphite powder, solvents such as tetrahydrofuran, cyclohexanone, N-methylpyrrolidone, DOP,
Plasticizers such as DBP, TCP, etc. may be added to the blended composition. Next, the kneaded compounded composition is placed in a calender roll,
It is molded into a film or sheet using an extruder or the like. In order to improve moldability, a conventional lubricant may be added to the compounded composition in advance. The blended composition formed into a film or sheet is heated to 50 to 300°C in a heated air atmosphere to undergo a carbon precursor treatment. At this time, the chlorinated vinyl chloride resin and the vinyl chloride resin release hydrogen chloride gas to accelerate the curing of the furan resin. Furan resin is cured three-dimensionally by heating and hydrogen chloride gas. Therefore, no special curing agent needs to be added. In addition, in this carbon precursor treatment, chlorine or ozone may be added to the atmosphere as necessary. Furthermore, the solvent and plasticizer added to improve the kneading properties of the chlorinated vinyl chloride resin, the vinyl chloride resin, the furan resin, and the graphite powder are volatilized during the carbon precursor treatment. The time for the carbon precursor treatment depends on the composition of the compounded composition and the thickness of the molded product, but
~72 hours. The film or sheet shaped excipient that has been subjected to the carbon precursor treatment is heated to 800° C. or higher, preferably 1000° C. or higher, in an inert atmosphere such as nitrogen or argon to carbonize it. For carbonization of chlorinated vinyl chloride resin, vinyl chloride resin, and furan resin, it is possible to significantly shorten the conventional firing time, and a slow heating rate is set so that carbonization takes more than 100 hours at most. do not have to. Next, the present invention will be explained in more detail with reference to Examples. Example 1 Chlorinated vinyl chloride resin with chlorine content of 67% and degree of polymerization of 740 (Nicatemp T-870 manufactured by Nippon Carbide Co., Ltd.)
40 parts by weight, furan resin (Hitafuran manufactured by Hitachi Chemical Co., Ltd.)
30 parts by weight of VF302) and graphite powder (CSP manufactured by Nippon Graphite Co., Ltd.) having an average particle size of 7 μm were uniformly mixed using a Henschel mixer. Next, the blended composition was sufficiently kneaded using two heated rolls. After kneading, the mixture was molded using a calendar roll to obtain a sheet with a thickness of 2 mm. Place the obtained sheet in a heating oven at 150℃ for 6 hours.
Next, after performing a carbon precursor treatment at 180°C for 10 hours, the temperature was increased to 20°C/h until 300°C at 500°C.
It was heated at a heating rate of 40°C/h up to 1000°C and 100°C/h up to 1000°C, and after cooling, a carbon thin plate was obtained. Example 2 The two-roll kneaded product of Example 1 was pelletized using a pelletizer, and the pellets were made into pellets with a thickness of 0.1 using the T-die method.
It was extruded into a mm film. Next, the film was placed in a heating oven and subjected to carbon precursor treatment at 150°C for 3 hours and 180°C for 6 hours, then fired in a nitrogen atmosphere under the same conditions as in Example 1 to carbonize, and after cooling, the film was carbonized. A thin plate was obtained. Example 3 30 parts by weight of straight vinyl chloride resin with a degree of polymerization of 700 (Vinicron 4000LL manufactured by Mitsui Toatsu Co., Ltd.), 30 parts by weight of furan resin (Hitafuran VF302 manufactured by Hitachi Chemical Co., Ltd.), graphite powder with an average particle size of 7 μm (( Nippon Graphite Co., Ltd.
Mix 40 parts by weight of CSP) uniformly using a Henschel mixer. Next, the blended composition was put into a pressure kneader, thoroughly kneaded under heat and pressure, and molded using a calendar roll to obtain a sheet with a thickness of 5 mm. Place the sheet in a heating oven at 120℃6
heating to 300°C at a temperature increase rate of 5°C/h,
Carbon precursor treatment was performed. Then in a nitrogen atmosphere
Firing and carbonization were performed at a heating rate of 20°C/h up to 500°C and 100°C/h up to 1500°C, and a carbon thin plate was obtained after cooling. Comparative Example 1 Chlorinated vinyl chloride resin with chlorine content of 67% and degree of polymerization of 740 (Nicatemp T-870 manufactured by Nippon Carbide Co., Ltd.)
60 parts by weight, furan resin (Hitafuran manufactured by Hitachi Chemical Co., Ltd.)
VF302) 40 parts by weight were uniformly mixed using a Henschel mixer. The blended composition was then heated 2
Thorough kneading was carried out using this roll. After kneading, the mixture was molded using a calendar roll to obtain a sheet with a thickness of 2 mm. Place the resulting sheet in a heated oven
After performing carbon precursor treatment at 150°C for 6 hours and then at 180°C for 10 hours, it was heated to 300°C for 20 hours in a nitrogen atmosphere.
℃/h, 40℃/h up to 500℃, 100℃/h up to 1000℃
The mixture was heated at a temperature increase rate of 1000° C. for 3 hours to carbonize, and after cooling, a thin carbon plate was obtained. Comparative Example 2 The two-roll kneaded product of Comparative Example 1 was pelletized using a pelletizer, and the pellets were made into pellets with a thickness of 0.1 using the T-die method.
It was extruded into a mm film. Next, the film was placed in a heating oven and subjected to carbon precursor treatment at 150°C for 3 hours and 180°C for 6 hours, and then carbonized by firing in a nitrogen atmosphere under the same conditions as Comparative Example 1.
After cooling, a carbon thin plate was obtained. Comparative Example 3 50 parts by weight of straight vinyl chloride resin with a degree of polymerization of 700 [Vinicron 4000LL manufactured by Mitsui Toatsu Co., Ltd.], 50 parts by weight of furan resin [Hitafuran VF manufactured by Hitachi Chemical Co., Ltd.]
302] using a Henschel mixer. Next, the blended composition was put into a pressure kneader, thoroughly kneaded under heat and pressure, and molded using a calendar roll to obtain a sheet with a thickness of 5 mm. The sheet was placed in a heating oven and heated at 120° C. for 6 hours, then at a temperature increase rate of 5° C./h to 300° C. to perform a carbon precursor treatment. Then in a nitrogen atmosphere, 500
Firing and carbonization were carried out at a heating rate of 20°C/h up to 1500°C and 100°C/h up to 1500°C, and after cooling, a carbon thin plate was obtained. The test results and notes for the above Examples and Comparative Examples are summarized in Table 1.

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【table】

Claims (1)

[Claims] 1. A molded product obtained by mixing and kneading chlorinated vinyl chloride resin and/or vinyl chloride resin, furan resin, and graphite powder, and molding the resulting kneaded product into a film or sheet shape. A method for producing an impermeable carbon thin plate, which comprises subjecting the material to a carbon precursor treatment and then firing it in an inert atmosphere. 2. The manufacturing method according to item 1, wherein the chlorinated vinyl chloride resin and the vinyl chloride resin each have a degree of polymerization of 500 to 2000. 3 The furan resin is furfuryl alcohol resin,
1. The method for producing furfuryl alcohol-furfural co-condensed resin, furfuryl alcohol-phenol co-condensed resin, or a mixed resin thereof. 4. The production method according to item 1, wherein the graphite powder has an average particle size of 0.5 to 150 μm. 5. The manufacturing method according to item 1, wherein the amount of graphite powder added is 2 to 50% by weight of the blended composition. 6 The first kneading is carried out under heating at 200°C or less.
Manufacturing method of section. 7 The carbon precursor treatment is carried out in an air atmosphere for 50~
The manufacturing method of paragraph 1, which is carried out by heating to 300°C. 8. The manufacturing method of paragraph 1, in which the firing is performed at 800°C or higher.