JPH0599577A - Fabrication of cylindrical carbon fiber heat insulating material - Google Patents

Abstract

PURPOSE:To fabricate a high density cylindrical carbon fiber heat insulating material without any strain and without non-effective work such as formation of a metal mold for each article by bonding strips of graphitized carbon fiber molded heat insulating material with an adhesive and thereafter carbonizing the same material. CONSTITUTION:A cylindrical carbon fiber heat insulating material is chiefly employed as a heat insulating material for a high temperature furnace in non- oxidizing atmosphere. To fabricate cylindrical carbon fiber heat insulating material, strips of graphitization carbon fiber molded heat insulating material are bonded with an adhesive and are thereafter carbonized. For example, a graphitization carbon fiber molded heat insulating material is cut into many pieces. A graphite adhesive solution is applied on cut edge surfaces of the cut members to provide a predetermined thickness film, and finally finished into a cylinder. Hereby, any strain such as creasing and folds is prevented from being produced, and hence non-effective work such as preparation of metal mold for each desired article is eliminated.

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 insulating material which is mainly used as a heat insulating material for a high temperature furnace in a non-oxidizing atmosphere.

[0002]

2. Description of the Related Art Carbon fibers have a content of 2 in a non-oxidizing atmosphere.
Since it does not wear even at high temperatures of 500 ° C or higher and maintains high strength, a thermosetting resin is molded into a tubular or plate shape using a binder, and this is carbonized and then graphitized. It is known that it has fine pores generated by the entanglement of and can be suitably used as a heat insulating material having shape retention for a high temperature furnace.

A heat insulating material produced by molding such carbon fiber is obtained by crushing carbon fiber, mixing it with a thermosetting resin serving as a binder, molding it, and then carbonizing and graphitizing it. Some types are available, but because of the ease of molding and the ease with which large-sized ones can be manufactured, a carbon fiber felt, web, non-woven fabric, or paper that is impregnated with or attached with a binder is wrapped around the core material. The method of obtaining a molded product by pressing after molding or after arranging in a mold is superior.

As a conventional technique for producing a tubular molded body by the latter method, for example, first, a carbon fiber felt obtained by impregnating or adhering a thermosetting resin on a tubular core material,
Wrap a web, non-woven fabric, paper, etc., and then sandwich this between, for example, two cylindrical outer halves, press and squeeze until the desired wall thickness is reached, the so-called mold tube method, or There is a rolled tube system in which a felt of carbon fiber impregnated or adhered with a thermosetting resin is wound around a core material by a hot roll and a pressure roll.

[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 mold tube method, felt or the like wound and laminated on the core material may be bent when the outer mold is narrowed down, causing deformation or peeling between layers during subsequent carbonization or 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 a problem is unlikely to occur, but in the case of bulky materials such as felt, thermocompression bonding will be insufficient unless the molding speed is slowed down, and the molding pressure is released except for the part sandwiched by the rolls. As a result, the wrapped felt or the like swells and becomes 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 manufacture a molded body having a high density.

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 and specifications are individually different, the manufacturing must be started after the ordering. There is a problem that the manufacturing period is longer than that of a plate-shaped product that can be stored as an inventory after it has been carbonized and graphitized in terms of size, and it is not in line with the recent demand for shorter delivery times. ..

Further, since the dimensions are different from one another, it is necessary to arrange the core material, the outer die, and the like for each dimension to be manufactured.
There are problems that the manufacturing cost of the mold is high, a storage place for the mold is required, and a mold of heavy weight must be handled. Furthermore, if there is no mold suitable for the diameter of the desired tubular carbon fiber heat insulating material, it must be molded into a size larger than the desired size and finally cut into the desired size, resulting in loss. In addition, if the length of the desired tubular carbon fiber heat insulating material is less than or equal to the mold size, or if there are large cutouts or cutouts in the desired shape, it is possible to effectively use the entire molded product. You can't do that, and you'll still lose. Loss related to the length of the desired tubular carbon fiber heat insulating material can be prevented by adjusting the width of the carbon fiber felt, web, non-woven fabric, paper, etc. used in advance to the desired length, but in practice the structure of the manufacturing facility It is difficult in terms of workability and workability.

[0008]

Then, the inventors of the present invention have made a study by paying attention to such a problem, and as a result, obtained by a method such as cutting a plate-shaped carbon fiber molded heat insulating material which has been subjected to graphitization treatment in advance. The strip-shaped graphitized carbon fiber molded heat insulating material is assembled into a tubular shape by adhering it with an adhesive, like a tub, and then carbonized to develop the strength of the adhesive and become integrated. As a result of realizing that a tubular carbon fiber heat insulating material can be obtained, the present invention has been completed.

That is, an object of the present invention is an inefficient work such as creating a mold for each desired product without causing distortion such as wrinkles and bending which is likely to occur in the conventional manufacturing method. The purpose of the present invention is to provide a method for producing a tubular carbon fiber heat insulating material that does not require the above. It is easily achieved by a method of manufacturing a fiber insulation material.

The present invention will be described in detail below. In addition, in the present specification, the tubular carbon fiber heat insulating material means that the cross section in a plane perpendicular to the axis of the tube is polygonal or circular. The strip-shaped graphitized carbon fiber molded heat insulating material used in the present invention is not particularly limited, but it is usually obtained from a plate-shaped carbon fiber molded heat insulating material by cutting into a desired size in terms of production. Advantageous and preferred. This is because the plate-shaped carbon fiber molded heat insulating material can be easily molded by a hot plate press and does not require various molds unlike the case of molding into a tubular shape. Moreover, in terms of quality, there is little occurrence of bending between the laminated layers, and the density can be easily controlled. Therefore, even if carbonization or graphitization is performed, peeling or deformation is less likely to occur due to the fact that it is plate-shaped.

Further, even if they are assembled into a cylindrical shape and integrated,
Since it is possible to use a strip-shaped carbon fiber molded heat insulating material which has already been carbonized and graphitized, it is possible to greatly shorten the manufacturing period. In addition, according to the length of the product to be combined and integrated, or the notch and cutout part can be cut out from the plate-shaped carbon fiber molded heat insulating material by shortening that amount from the beginning, and the loss can be wide. It is possible to reduce. The strip-shaped graphitized carbon fiber molded heat insulating material may be any one regardless of the type of carbon fiber used and the method of manufacturing the molded heat insulating material. However, in order to prevent a dimensional change when exposed to the temperature for final use after finishing the tubular carbon fiber heat insulating material, it is preferable that heat treatment is applied at least at that temperature or higher.

Further, the length may be the same as the length of the tubular heat insulating material to be finally assembled, but when high accuracy is required in the length direction or the unevenness of the end face in the length direction is strict. In this case, the length may be set to about 20 mm, assembled into a tubular shape, and then machined to adjust the length. The width of the strip-shaped graphitized carbon fiber molded heat insulating material may be determined depending on how many sides of the tube are to be formed and the size of the tube. When the number of surfaces of the cylinder is small, the number of steps for assembling is reduced, but the obtained cylinder becomes far from the perfect circular shape. Therefore, it is generally determined that the outer diameter of the cylinder is 500, although it is determined by the shape required for each product.
In the range of up to 1500 mm, it is preferable to have about 24 to 36 faces, so that the width of the strip-shaped carbon fiber molded heat insulating material is 4.
It is about 0 to 200 mm.

Regarding the thickness, the required thickness itself may be used, but in the case of finishing the product into a cylindrical shape and then cutting it into a perfect circle, it is necessary to consider the thickness of the cutting allowance. There is. Since each strip-shaped carbon fiber molded heat insulating material is assembled into a tubular shape, it is necessary to make an angle on the end face of the thickness surface in order to bond them to each other. This angle is a value obtained by dividing 360 degrees by the number of side surfaces, and is, for example, 15 degrees for a tetrahedron and 10 degrees for a 36-sided body. However, of course, if the desired shape is an oval or the like, it may be designed at an appropriate angle. This angle may be provided only on one side of the end surface of the thickness surface, or may be distributed to both end surfaces. Since a predetermined number of strip-shaped carbon fiber molded heat insulating materials with this angle are pasted together to form a cylinder having a circumferential angle of 360 degrees, the angle processing should be performed as accurately as possible and there is no unevenness on the processed surface. Preferably.

The strip-shaped carbon fiber molded heat insulating materials processed into predetermined dimensions and shapes are then attached to each other with an adhesive. The adhesive used at this time is preferably one for carbon material, and specifically, the adhesive for carbon material is mainly composed of carbon powder and thermosetting resin. For example, "V58a" manufactured by Zigli Co., Some products such as "Newcoat GC" from Dainippon Ink and Chemicals, Inc. are commercially available. In both cases, the powdery substance is used by dissolving it in a solvent such as alcohols and ketones such as methanol and ethanol, so that a solution is prepared using these solvents or a designated solvent. The heat insulating material is porous and easily penetrates the solution, so only the solution concentration is 2 which is the specified concentration that is usually used for each adhesive.
It is easier to obtain preferable results in terms of adhesiveness when the amount is set to 4 times.

The adhesive for the carbon material which is melted and sufficiently stirred and mixed is applied to the adhering 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, but the adhesive solution is applied. The amount is preferably such that a liquid film having a thickness of about 0.3 to 1.0 mm is formed on the coated surface. If the surface of the member can be seen, the coating amount is insufficient, and if a film having a thickness of 1 mm or more is formed, it is excessive and wasteful.

Since an adhesive for carbon materials does not exhibit strength unless carbonized, a combination of strip-shaped carbon fiber molded heat insulating materials can be carried over to a carbonization facility and transported at 800 ° C. or higher so that it can be moved. It is preferable to perform it on a table or board made of a carbon material or a metal material having the above heat resistance. Rather than assembling the members one after another, 3-4
It is preferable from the viewpoint of workability as well as the assembling with high accuracy that the members are combined into a panel shape, and the panel-shaped members are further combined to form a tubular shape. Furthermore, it is effective to place the full-scale combination plan drawing on the table or board for assembling and work while confirming the assembled state with high accuracy.

The product assembled into a tubular shape is then carbonized to develop the adhesive strength. Before that, a binding force is applied from the outer periphery of the cylinder to enhance the adhesiveness of the adhesive surface, and the shape of the product is improved during movement. It is desirable not to distort. As this method, a string or tape-like material having a heat resistance of 800 ° C. or higher and which does not extend so much, for example, a metal tape or a string of carbon fibers may be used for binding. It is more preferable that the carbon fiber string is bound tightly because the binding state can be continued even in the carbonization treatment.

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

It is preferable that 1 is added prior to the carbonization treatment.
It is better to perform heat treatment (curing) at a temperature of 00 to 250 ° C. for 2 to 10 hours, and stronger adhesion can be expected. The tubular carbon fiber insulation after the above processing can be handled as a complete monolithic carbon fiber insulation,
After that, the required drilling or the like or the coating can be performed according to the usual process. If necessary, prior to the above processing, coating, etc.,
It is also possible to change from a tubular shape to a perfect circular tubular 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 as long as the gist thereof is not exceeded. (Example-1) 1500 x 1000 mm, thickness 60 mm
As shown in Fig. 1, 24 pieces of carbon fiber molded heat insulating material in strip form (12 pieces are 1350 mm long, 12 pieces are 940 mm long) from the graphitized carbon fiber molded heat insulating material ("Carbolite" manufactured by Mitsubishi Kasei Co., Ltd.) It was cut out. Then, a graphite adhesive solution ("V-
58a ″ (1 part by weight dissolved in 0.5 part by weight of methanol) was applied to the extent that a film having a thickness of about 0.5 mm was applied and assembled, and finally the tube shape shown in FIG. 2 was obtained.

Then, a bundle of carbon fiber yarns ("Dilead" manufactured by Mitsubishi Kasei Co., Ltd.) was bundled, and the three ends of the cylinder were squeezed up until the graphite adhesive solution slightly exudes and tightly bound. Then, it was heat-treated at 200 ° C. for 2 hours in a hot-air circulation type drying furnace while being placed on the graphite plate having a thickness of 20 mm used as a stand for assembling. Then, in a carbonization furnace, under a nitrogen atmosphere, the temperature is raised to 1000 ° C.
Hold at 0 ° C. for 1 hour. The tubular carbon fiber heat insulating material having 24 side surfaces after the carbonization treatment had sufficient strength to be handled as an integral body and had no abnormal appearance such as distortion.

Comparative Example-1 Same size as Example-1 (outer diameter 9
30mmφ, length 1350mm, wall thickness 60mmt),
It was manufactured by a method in which a cylindrical heat insulating material having two notches with a length of 400 mm and an opening angle of 90 degrees was wound around a core mold while pressurizing a carbon fiber web impregnated with a phenol resin (carbon fiber). Is the same as the product used in the example).

A carbon fiber web is wound around a mold and fixed with an outer mold to obtain a molded body, followed by hardening treatment, carbonization treatment,
Graphitized to finally have an outer diameter of 931 mm and a length of 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 processed, and two notches having an opening angle of 90 degrees and a length of 400 mm were made. At this time, due to internal residual stress, the cylindrical section on the side with the notch has a maximum of 3 mm
It was distorted to an oval shape.

[Brief description of drawings]

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

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

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location F23M 5/02 7815-3K F27D 1/00 G 7727-4K

Claims (1)

[Claims] 1. A method for producing a tubular carbon fiber heat insulating material, comprising adhering strip-shaped graphitized carbon fiber molded heat insulating material with an adhesive and then carbonizing the same.