JPH03248838A - Heat insulation material - Google Patents

Abstract

PURPOSE:To constitute the title material so that fracture is rare, deterioration in dimensional accuracy can be corrected and the same is superior in elasticity, adhesion, shape retention and heat insulation properties, by a method wherein a molded layer obtained by joining carbon fibers to each other by carburized or graphitized thermosetting resin or pitch and a carbon fiber felt layer are laminated. CONSTITUTION:A molded layer 1 is formed by a method wherein a fiber or a carbon fiber felt which can be made into carbon fiber is impregnated with graphitizable thermosetting resin, compression-molded and graphitized. A carbon fiber felt layer 2 is obtained by a method wherein felt is manufactured by performing mixed spinning, for example, of a phenolic resin fiber contracting by firing with the carbon fiber, the phenolic resin fiber is contracted at the time of the firing and carburized or graphitized. A carbonaceous binder layer 3 laminating and integrating the molded layer 1 and carbon fiber felt layer 2 is formed by a method wherein carburizable or graphitizable pitch or the thermosetting resin is applied to the surface of the carbon fiber felt layer 2 and the surface of the minute molded layer 1 and carburization and graphitization are performed.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to a heat insulating material with excellent heat insulation properties in a high temperature range.

[Prior Art and Problems to be Solved by the Invention] Carbon fiber felt is widely used as a heat insulating material for high-temperature furnaces such as ceramic firing furnaces, vacuum evaporation furnaces, and semiconductor single crystal growth furnaces. In this carbon fiber felt, as the bulk density of the carbon fiber felt increases, the heat insulation performance in a high temperature range improves.

However, the bulk density of carbon fiber felt alone is 0.0.
7g/cn? It is very small and its shape retention is poor.

Therefore, in order to improve heat insulation and shape retention in high temperature ranges, it is necessary to compress carbon fiber felt to increase bulk density.

In view of the above points, Japanese Patent Publication No. 5O-8598 (No. 1) discloses that carbon fiber felt is impregnated with a resin that can be carbonized or graphitized, the impregnated felt is compressed and hardened, and then molded to be carbonized or graphitized. A method of manufacturing a heat insulating material has been proposed.

However, the molded insulation material obtained by this method is
Since it is integrated with carbonized resin and is hard, it has poor elasticity and cushioning properties, and the heat insulating material is easily damaged during processing or installation in the furnace. Further, when the end faces of the heat insulating shrine are joined and installed in the furnace, it is difficult to align the joined end faces and to tightly join the joined end faces, so a gap is created between the joined end faces, and the heat insulation properties are deteriorated. Furthermore, during firing after resin impregnation, warping is likely to occur, resulting in a decrease in dimensional accuracy.

Therefore, an object of the present invention is to provide a heat insulating material that is less likely to be damaged, which means that the J method accuracy can be avoided, and that has excellent elasticity, adhesion of the joint end surface, shape retention, and heat insulation properties. be.

[Structure of the Invention] The present invention provides a heat insulating material in which a molded layer in which carbon fibers are bonded by carbonized or graphitized thermosetting resin or pitch, and a carbon fiber felt layer are laminated.

Definitions of terms used in this specification are as follows.

Carbon fiber means carbonized or graphitized fiber.

Flame-retardant treatment refers to the treatment of fibers other than pitch-based fibers, such as
This refers to a treatment in which a heat-resistant layer is formed on the surface by heating at a temperature of about 200 to 450°C in the presence of oxygen to prevent melting during firing. The infusible treatment refers to a treatment in which pitch-based fibers are heated, for example, at a temperature of about 200 to 450° C. in the presence of oxygen to form a heat-resistant layer on the surface to prevent melting during firing.

Carbonization means that the polymer fibers, pitch, etc. are
It means firing at a temperature of about 450 to 1500°C. Graphitization means firing treatment at a temperature of, for example, about 1500 to 3000°C, and is included in the concept of graphitization even when it does not have the crystal structure of graphite.

FIG. 1 is a schematic cross-sectional perspective view showing an example of the heat insulating material of the present invention, and this example shows a flat heat insulating material.

The heat insulating material consists of a molded layer (1) in which carbon fibers are bonded by a thermosetting resin or pitch made of carbonized or graphitized carbon fibers, and a carbon fiber felt layer (2) that does not contain any resin, etc. as a carbonaceous binder layer. (3) are laminated. The above molding layer (1)
can be formed by impregnating a carbon fiber or carbon fiber felt with a thermosetting resin or pitch that can be carbonized or graphitized, compression molding, and carbonizing or graphitizing.

In addition, when impregnating a thermosetting resin, the above molding layer (
In 1), it is preferable to heat and harden the thermosetting resin during compression molding. The molding layer (1) is formed by sucking a suspension containing fibers that can be made into carbon fibers or carbon fibers, and a thermosetting resin or pitch that can be carbonized or graphitized using a suction mold. It can also be formed by a suction molding method in which the above components are deposited on the surface of a mold, or by carbonizing or graphitizing the molded product after molding by a paper making method.

Examples of fibers and carbon fibers that can be made into carbon fibers include:
Examples include fibers made of polymers such as polyacrylonitrile, rayon, cellulose, and phenol resin, and pitches such as petroleum pitch and coal pitch, and one or more of them may be used. These fibers, for example, have a fiber diameter of 5 to
Those having an appropriate fiber diameter of about 30 μm can be used.

The felt of the carbon fiber felt layer (2) is made by a conventional method,
That is, it can be produced by passing through a carding step and a needle punching step.

Examples of felt include phenol resin, furan resin, urea resin, melamine resin, unsaturated polyester, vinyl ester resin, diallyl phthalate resin, epoxy resin, thermosetting polyimide, thermosetting acrylic resin, and the like. Among these resins, phenol resins, furan resins, and the like, which have excellent adhesive properties and a large residual carbon content, are preferred. These resins can be used alone or in combination of two or more.

The content of the resin can be set within a range that does not impair shape retention, for example, 5 to 75% by weight, preferably 10 to 50% by weight.
It is about mm%.

The bulk densities of the molded layer (1) and the carbon fiber felt layer (2) can be appropriately set depending on the temperature of the furnace to which they are applied, and may be the same or different. Carbon fiber felt layer (2)
Since the bulk density of the carbon fiber felt layer (2) is generally small, in order to improve the heat insulation properties in a high temperature range, it is preferable that the bulk density of the molded layer (1) is larger than that of the carbon fiber felt layer (2). Moreover, it is preferable to install the molded heat insulating material so that the molded layer (1) is located on the high temperature side of the furnace. The bulk density of the molding layer (1) is usually O11 to 0.5 g/cm, particularly 0.1 to 0.3 g/cm.
It is preferable that the amount is within a certain range.

The bulk density of the carbon fiber felt layer (2), which does not contain a thermosetting resin and has excellent cushioning properties, elasticity, etc., is not particularly limited, and may be within a wide range, for example, 0.05 to 0°2 g/c.
It can be set within a range of about m. Note that the bulk density is 0.1.
The carbon fiber felt layer (2) of g/cm or more is, for example,
It can be obtained by blending phenolic resin fibers that shrink upon firing (for example, kynol) with carbon fibers to produce felt, causing the phenolic resin fibers to shrink during firing, and carbonizing or graphitizing the fibers.

The thickness of the molding layer (1) and the carbon fiber felt layer (2) can be set appropriately depending on the temperature of the furnace to which it is applied, but the thickness of the molding layer (1)
) is usually about 1 to 100 mm, and the thickness of the carbon fiber felt layer (2) is usually about 3 to 50 mm.

The carbonaceous binder layer (3), which laminates and integrates the molding layer (1) and the carbon fiber felt layer (2), combines carbonizable or graphitizable pitch or the thermosetting resin with the molding layer (1) and the carbon fiber felt layer (2). It can be formed by coating at least one of the carbon fiber felt layers (2), preferably on the surface of the molded layer (1) having a dense surface, and carbonizing or graphitizing it. One or more types of pitch or resin can be used. Among the above resins, thermosetting resins, particularly phenolic resins, are preferred.

In order to increase the bonding strength between the molding layer (1) and the carbon fiber felt layer (2), the carbonaceous binder layer (3) preferably contains a carbonaceous filler. This carbonaceous filler is used in the molding layer (1
) and the carbon fiber felt layer (2) are filled in, thereby increasing the bonding area.

Examples of the carbonaceous filler include carbonaceous small spheres such as mesocarbon micropieces, coke pleats, fillers that can be carbonized or graphitized, such as bulk mesophase carbon obtained by infusible treatment of crushed pitch, coal, etc. ℃
It may also be low-temperature calcined coke that has been carbonized at a relatively low temperature and pulverized.

Among these carbonaceous fillers, mesocarbon microbeads are preferred. These carbonaceous fillers are used singly or in a mixture of two or more, and are included in the carbonaceous binder (3), usually in an amount of 5 to 7
It contains 5% by weight, preferably 10 to 50% by weight.

In order to further increase the bonding strength, the carbonaceous binder layer (3) may contain milled carbon fibers in addition to the above-mentioned carbonaceous filler. This milled carbon fiber is usually 5 to 25% by weight.
It can be contained to some extent.

In such a heat insulating material, the molded layer (1) has carbon fibers integrated with carbonized or graphitized resin or pitch, so it is hard, has a large bulk density, and has excellent heat insulation properties. Therefore, the molded layer (1) provides shape retention and excellent heat insulation properties to the heat insulating material. On the other hand, the carbon fiber felt layer (2) has excellent elasticity and cushioning properties, can prevent damage to the molded layer (1), and corrects deterioration in dimensional accuracy such as warping caused by firing. In addition, the carbon fiber felt layer (2) ensures adhesion between the joint end faces and further improves heat insulation.

FIG. 2 is a schematic cross-sectional perspective view showing another example of the present invention.

In this example, in a heat insulating material in which a molded layer (11) and a carbon fiber felt layer (12) are laminated with a carbonaceous binder layer (13), the surface of the molded layer (11) is A sheet (14) is laminated with a carbonaceous binder layer (13). Examples of the carbonaceous sheet (14) include a carbon sheet obtained by firing a carbonizable or graphitizable sheet in an inert gas or vacuum, preferably a graphite sheet. The carbonaceous sheet (14) may have an appropriate thickness, but is usually about 0.1 to 1 mm, preferably about 0.1 to 1 mm,
It is about 2 to 0.75 mm. Graphite sheet is
For example, graphite is treated with a strong acid such as sulfuric acid to make it fat-swelled and made into a flexible sheet form by a method such as rolling extrusion, and generally has a density of about 0.5 to 1.6 g/cut.

Since the carbonaceous sheet (14) has excellent airtightness, when laminating this carbonaceous sheet (14) on a heat insulating material, it is possible to further improve powder resistance, wind resistance, durability, and shape retention. can.

Note that the carbonaceous sheet (14) has a carbonaceous binder layer (
According to ■3), it is only necessary to laminate it on the surface of the molding layer (11) and/or the carbon fiber felt layer (12) which will be on the high temperature side during use, and even if it is not laminate on the surface of the carbon fiber felt layer (12). However, it is preferable to laminate a carbonaceous binder layer (13) on the surface of the molding layer (11). Further, the carbonaceous binder layer (13) preferably contains at least a carbonaceous filler, as described above.

Note that the heat insulating material is not limited to a flat plate shape, but may be a curved plate shape or a hollow cylindrical shape. FIG. 3 is a schematic cross-sectional perspective view showing still another example of the present invention. In this example, the carbonaceous binder layer (
23), a carbon fiber felt layer (22) is laminated on the outer surface of the hollow cylindrical molded layer (21). The heat insulating material laminated with the carbon fiber felt layer (22) on the outer surface prevents the molded layer (21) from coming into direct contact with the furnace wall when installed, so the heat insulating material will not be damaged and the carbon fiber felt layer (22) will not be damaged. The layer (22) is in close contact with the furnace wall.

The carbon fiber felt layer may be laminated on both sides of the molded layer via a carbonaceous binder layer. Further, a plurality of molded layers and a plurality of carbon fiber felt layers may be alternately laminated using a carbonaceous binder layer. In this case, the molded layer and the carbon fiber felt layer may have different bulk densities.

] 1 Furthermore, in order to further improve the adhesion of the joint end surfaces, a carbon fiber felt layer may be laminated on the end surfaces of the molded layer.

[Effects of the Invention] According to the heat insulating material of the present invention, since the molded layer and the carbon fiber felt layer are laminated, there is less chipping and χj
In addition to being able to correct the decrease in process accuracy, it also has excellent elasticity, adhesion of the joint end surfaces, shape retention, and heat insulation.

[Examples] The present invention will be described in more detail below based on Examples.

Example: Pitch-based carbon fiber (trade name: Dona Carbo 5, manufactured by Donatsuku Co., Ltd.)
221) with a thickness of 10 mm (bulk density 0.05 g/metal), resol type phenolic resin (manufactured by Gunei Kagaku ■, trade name: Regitop P)
About 60% by weight methanol solution of L3820A)
A bi-impregnated carbon fiber felt with a solvent content of 60% by weight was prepared by impregnating the carbon fiber felt with the same amount by weight and air drying. This impregnated felt was laminated and heated and compressed to harden the phenol resin to obtain a molded article having a thickness of 22 mm and a bulk density of 0.16 g/cnf.

The phenolic resin solution was applied to one side of the molded body, and a carbon fiber felt (bulk density 0.05 g/cnf) of 0 mm in thickness made of pitch-based carbon fiber (trade name: Dona Carbo 5221, manufactured by Donatsu) was applied. They were laminated and compressed and heated again to harden the phenol resin.

Next, the laminate was heated to 2000° C. in a nitrogen gas atmosphere, fired, and graphitized.

The obtained insulation material has a thickness of 30 mm and a bulk density of 0. 1
3 g/aa and had shape retention properties, and the carbon fiber felt layer on one side was highly elastic.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional perspective view showing an example of the heat insulating material of the present invention, Fig. 2 is a schematic cross-sectional perspective view showing another example of the present invention, 3 Fig. 3 is a schematic cross-sectional view showing yet another example of the present invention. It is a cross-sectional perspective view. (1) (11) (21)...Molding layer, (2) (12
) (22)...carbon fiber felt layer, (3) (1
3) (23)...carbonaceous binder layer, (14)...
carbonaceous sheet

Claims (4)

[Claims] 1. A heat insulating material characterized in that a molded layer in which carbon fibers are bonded by carbonized or graphitized thermosetting resin or pitch and a carbon fiber felt layer are laminated. 2. The heat insulating material according to claim 1, wherein the molded layer and the carbon fiber felt layer are laminated with a carbonaceous binder containing at least a carbonaceous filler. 3. The heat insulating material according to claim 1 or 2, wherein a carbonaceous sheet is laminated with a carbonaceous binder on the surface of the molded layer. 4. The heat insulating material according to claim 1, wherein the molded layer has a larger bulk density than the carbon fiber felt layer.