JP3163683B2 - Manufacturing method of tubular carbon fiber insulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a tubular carbon fiber heat insulator used mainly as a heat insulator for a high-temperature furnace in a non-oxidizing atmosphere.

[0002]

2. Description of the Related Art Carbon fibers are used in non-oxidizing atmospheres.
It does not wear even at high temperatures of 500 ° C or higher, and maintains high strength, so it is molded into a tube or plate using a thermosetting resin as a binder, carbonized, and further graphitized to obtain a molded product that is made of carbon fiber. It has been known that it has fine pores caused by entanglement of the material and can be suitably used as a heat insulating material having shape retention for a high-temperature furnace.

[0003] As a heat insulating material produced by molding such carbon fiber, carbon fiber is obtained by pulverizing carbon fiber, mixing it with a thermosetting resin as a binder, molding the mixture, then carbonizing and graphitizing. Although there are types, it is easy to mold and it is easy to manufacture large-sized ones. Wound carbon fiber felt, web, non-woven fabric or paper impregnated with or attached to a binder around the core material. The method of obtaining a molded body by press-molding after arranging in a mold or after arranging in a mold is superior.

[0004] As a conventional technique for producing a cylindrical molded article by the latter method, for example, first, a carbon fiber felt in which a thermosetting resin is impregnated or adhered to a cylindrical core material,
A web, a non-woven fabric or a paper is wound, and thereafter, this material is sandwiched between, for example, two halved cylindrical outer molds, pressed and squeezed until a desired wall thickness is obtained. And a rolled tube method in which a carbon fiber felt or the like impregnated or adhered with a thermosetting resin by a hot roll and a pressure roll is wound around a core material.

[0005]

However, when a relatively bulky material such as felt, web, nonwoven fabric or paper of carbon fiber is molded by such a method, especially when the thickness of the molded body is large, In the case of the mold tube method, felt or the like wound and laminated on the core material slides when the outer die is narrowed, which may cause deformation or peeling between laminations during subsequent carbonization and graphitization. There is a problem that the outer surface of the tubular carbon fiber heat insulating material is wrinkled. On the other hand, in the rolled tube method, such problems are unlikely to occur, but in the case of bulky materials such as felt, if the molding speed is not slowed down, thermocompression bonding will be insufficient and the molding pressure will be released except for the part sandwiched between the rolls As a result, the wound felt or the like swells, resulting in a distorted tubular carbon fiber heat insulating material. Further, there is a problem that it is difficult to control the density of the molded body, and it is difficult to produce a molded body having a high density.

[0006] In addition to the above-mentioned problems, most of the tubular carbon fiber heat insulating materials are made to order products, and since the dimensions, specifications and the like are different from each other, production must be started after molding after receiving the order. There is a problem that the production period is longer than a plate-shaped (board-shaped) product that can be kept in stock after carbonization and graphitization processing is completed in dimensions, and it is in a situation where it has not been able to meet the demand for shorter delivery time, which has recently been strengthened. .

[0007] Further, since the dimensions are individually different, molds such as a core material and an outer mold must be prepared for each dimension to be manufactured.
There are also problems such as increased manufacturing costs of the mold, a need for a storage space for the mold, and the need to handle heavy-weight molds. Furthermore, if there is no mold that matches the diameter of the desired tubular carbon fiber heat insulating material, it must be molded to a size larger than the desired size and finally cut to the desired size, resulting in loss. In addition, when the length of the desired tubular carbon fiber heat insulating material is less than or equal to the size of the mold, or when the desired shape has a large cutout or cutout, it is possible to effectively use all of the molded material. Failure to do so still results in loss. The length of the desired tubular carbon fiber insulation can be prevented by adjusting the width of the felt, web, nonwoven fabric or paper of the carbon fiber used to the desired length in advance, but in practice the structure of the manufacturing equipment It is difficult from the viewpoint of workability.

[0008]

Means for Solving the Problems Accordingly, the inventors of the present invention have paid attention to such problems and as a result of repeated examinations, as a result, obtained a method such as cutting a plate-like carbon fiber molded heat insulating material which has been subjected to a graphitization treatment in advance. The strip-shaped graphitized carbon fiber molded heat insulation material is combined with an adhesive as if assembling a tub, combined into a cylinder, then carbonized to develop the strength of the adhesive and integrated. The present invention was completed by noting that a tubular carbon fiber heat insulating material was obtained.

That is, an object of the present invention is to provide an inefficient work such as creating a mold for each desired product without generating distortion such as wrinkles or sliding, which is likely to occur in a conventional manufacturing method. It is an object of the present invention to provide a method of manufacturing a tubular carbon fiber heat insulating material that does not require a tubular carbon fiber, in which a strip-shaped graphitized carbon fiber molded heat insulating material is bonded with an adhesive, and then carbonized. It is easily achieved by the method of manufacturing the fiber insulation.

Hereinafter, the present invention will be described in detail. In this specification, the tubular carbon fiber heat insulating material means a material having a polygonal or circular cross section in a plane perpendicular to the axis of the cylinder. Although the strip-shaped graphitized carbon fiber molded heat insulating material used in the present invention is not particularly limited, it can usually be obtained by cutting out a plate-shaped carbon fiber molded heat insulating material into a desired size. Advantageous and preferred. This is because the plate-shaped carbon fiber molded heat insulating material can be easily formed by a hot plate press, and does not require various molds unlike the case of forming into a cylindrical shape. Also, in terms of quality, there is little occurrence of bending between the layers, and the density can be easily controlled. Therefore, even if the carbonization or graphitization treatment is performed, peeling or deformation is little caused by the plate shape.

[0011] Further, even if it is assembled and integrated into a cylindrical shape,
Since it is possible to use a strip-shaped carbon fiber molded heat insulating material which has already been carbonized and graphitized, the production period can be significantly reduced. Furthermore, according to the length of the product to be combined and integrated, or cut out, the cut-out part may be cut out from the plate-shaped carbon fiber molded heat insulating material by shortening it from the beginning, and the loss is also large. It is possible to reduce. The strip-shaped graphitized carbon fiber molded heat insulating material may be any material regardless of the type of carbon fiber used or the method of manufacturing the molded heat insulating material. However, in order to prevent the dimensional change from occurring when the cylindrical carbon fiber heat insulating material is finally subjected to the temperature to be used after it is finished, it is preferable that a heat treatment at least at that temperature is applied.

The length may be the same as the length of the cylindrical heat-insulating material to be finally assembled. However, when high precision is required in the length direction or the degree of unevenness of the end face in the length direction is strictly required. In this case, the length may be increased by about 20 mm, assembled into a cylindrical shape, and then machined to adjust the length. The width of the strip-shaped graphitized carbon fiber heat insulating material may be determined each time by the number of sides of the cylinder and the size of the cylinder. When the number of surfaces of the tube is small, the number of steps for assembling is reduced, but the obtained tube is far from a perfect circular shape. Therefore, although determined by the shape required for each product, generally, the outer diameter of the cylinder is 500
In the case of a thickness of about 1500 mm, the thickness is preferably about 24 to 36 faces.
It is about 0 to 200 mm.

[0013] The thickness may be the required thickness itself, but it is necessary to take into account the thickness of the cutting allowance when the cylinder is finished and then cut into a perfect circle. Yes. Since each strip-shaped carbon fiber molded heat insulating material is assembled into a cylindrical shape, it is necessary to form an angle on the end face of the thickness surface in order to adhere to each other. This angle is a value obtained by dividing 360 degrees by the number of side surfaces. For example, the angle is 15 degrees in the case of a 24-hedron and 10 degrees in the case of a 36-hedron. However, if the desired shape is an elliptical shape or the like, the angle may be designed at an appropriate angle. This angle may be provided only on one side of the end face of the thickness plane, or may be distributed to both end faces. A predetermined number of strip-shaped carbon fiber insulation materials with this angle are stuck together and finished into a cylinder with a 360-degree peripheral angle. Therefore, the angle processing should be performed as accurately as possible, and there is no unevenness on the processing surface. Is preferred.

The strip-shaped carbon fiber molded heat insulating material processed into a predetermined size and shape is then bonded together with an adhesive. The adhesive used at this time is preferably one for carbon material. Specifically, the adhesive for carbon material is mainly composed of carbon powder and thermosetting resin. For example, “V58a” manufactured by Zigly Corporation, A product such as "Newcoat GC" of Dainippon Ink and Chemicals, Inc. is commercially available. In each case, a powdery substance is used by dissolving it in a solvent such as alcohols or ketones such as methanol and ethanol. Therefore, a solution is prepared using these solvents or a designated solvent. Insulation material is porous and easily penetrates the solution. Therefore, only the solution concentration is 2% of the specified concentration used for each adhesive.
If the ratio is set to up to 4 times, a favorable result in terms of adhesiveness can be easily obtained.

The adhesive for the carbon material, which has been dissolved and sufficiently stirred and mixed, is applied to the adhesive surface of the strip-shaped carbon fiber molded heat insulating material with a brush or the like, and the members are brought into close contact with each other and assembled. The amount is preferably such that a liquid film having a thickness of about 0.3 to 1.0 mm can be formed on the coated surface. If the bare surface of the member is visible, the amount of coating is insufficient, and if a film having a thickness of 1 mm or more is formed, it is excessive and wasteful.

[0016] Since the adhesive for carbon materials does not develop strength unless carbonized, the combination of strip-shaped carbon fiber molded heat insulating material is set at 800 ° C or higher so that the assembled tube can be carried to the carbonization treatment facility and moved. It is preferable that the heat treatment be performed on a table or a board made of, for example, a carbon material or a metal material. The assembling of the members is 3 to 4 rather than successively.
It is preferable to combine the members into a panel shape and further combine the panel-like members into a tubular shape in terms of workability and assembling with high accuracy. Further, a method of placing a full-scale combined plan on a table or a board for assembling and checking the state of assembling while working is effective in terms of finishing with high accuracy.

The product assembled into a cylindrical shape is then subjected to a carbonizing treatment to develop an adhesive strength. Before that, a binding force is applied from the outer periphery of the tube to enhance the adhesion of the adhesive surface, and the shape is formed when the product is moved. It is desirable not to be distorted. As this method, a string or a tape-like material having a heat resistance of 800 ° C. or more and which does not extend much, for example, a metal tape or a string of carbon fiber may be used for binding. In the case of binding with a carbon fiber string or the like, the binding state can be continued even in the carbonization treatment, which is more preferable.

The carbonization treatment is preferably carried out under an inert atmosphere, preferably 5 times.
The heating is performed at a temperature rising rate of 0 ° C./Hr or less to 800 ° C. or more, preferably 1000 ° C. or more. By this treatment, the organic component in the adhesive is carbonized, so that generation of gas and volatile matter when used as a heat insulating material is eliminated. If the rate of temperature rise is 50 ° C./Hr or more, the adhesive in the process may foam and the adhesive strength may be reduced. If the maximum temperature of the treatment is 800 ° C. or less, carbonization of the adhesive tends to be insufficient.

[0019] Preferably, prior to the carbonization treatment, 1
Heat treatment (curing) at a temperature of 00 to 250 ° C. for 2 to 10 hours is better, and stronger adhesion can be expected. The tubular carbon fiber insulation material after the above processing can be handled as a complete integral carbon fiber insulation material,
Thereafter, necessary drilling and the like, or coating and the like can be performed according to a normal process. Also, if necessary, prior to the above processing, coating, etc.,
The shape can be changed from a cylindrical shape to a perfect circular cylindrical shape by lathe cutting or the like.

[0020]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the examples unless it exceeds the gist. (Example-1) 1500 × 1000 mm, thickness 60 mm
As shown in FIG. 1, 24 strip-shaped carbon fiber molded heat insulators (12 were 1350 mm long, 12 were 940 mm long) from the graphitized carbon fiber molded heat insulator (“Carbolite” manufactured by Mitsubishi Kasei Co., Ltd.) Sa) I cut it out. Next, a graphite adhesive solution (Zigly “V-
58a "(1 part by weight dissolved in 0.5 part by weight of methanol) was applied so as to form a film having a thickness of about 0.5 mm, and assembled to finally form a cylindrical shape as shown in FIG.

Next, a bundle of carbon fiber yarns ("Dialead" manufactured by Mitsubishi Kasei Co., Ltd.) is squeezed by squeezing three places at both ends and the center of the cylinder until the graphite adhesive solution slightly exudes. Then, it was heat-treated at 200 ° C. for 2 hours in a hot-air circulating drying furnace while being placed on a graphite plate having a thickness of 20 mm used as a table when assembling. Then, in a carbonization furnace, the temperature was increased to 1000 ° C. in a nitrogen atmosphere,
Hold at 0 ° C. for 1 hour. The carbonized carbon fiber heat insulating material having 24 carbonized side surfaces had sufficient strength to be treated as an integral product, and had no abnormal appearance such as distortion.

(Comparative Example-1) Same dimensions as in Example-1 (outer diameter 9
30mmφ, length 1350mm, wall thickness 60mmt)
A cylindrical heat insulating material having two notches of 400 mm in length and 90 degrees open angle was wound on a core mold while pressing a carbon fiber web impregnated with a phenol resin, and molded by a method of molding (carbon fiber Are the same as those used in the examples).

The carbon fiber web is wound around a mold, fixed with an outer mold to obtain a molded product, and then cured, carbonized,
After graphitization, the outer diameter is 931 mm and the length is 1
A cylindrical carbon fiber molded heat insulating material having a thickness of 350 mm and a thickness of 60 mm was obtained. Next, this cylinder was machined, and two notches with an opening angle of 90 degrees and a length of 400 mm were made. At this time, the cylindrical cross section of the notched side due to internal residual stress is up to 3 mm
It was distorted to an elliptical shape.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the shape of a strip-shaped graphitized carbon fiber molded heat insulating material used in an embodiment of the present invention.

FIG. 2 is an explanatory view of a tubular carbon fiber heat insulating material prepared in an example of the present invention.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁷ Identification code FI C04B 35/80 BK

Claims (1)

(57) [Claims] 1. A method for producing a tubular carbon fiber heat insulating material, comprising bonding a strip-shaped graphitized carbon fiber heat insulating material with an adhesive, followed by carbonization.