JPS6343343B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a method for manufacturing carbon containers such as boats, crucibles, molds, etc. used for many molten metals, molten salts, etc.

Carbon has the property of not getting wet with molten metals and has high corrosion resistance against various molten baths, so it is used as a container for containing these.

Conventional technology Carbon boats and crucibles are generally manufactured by processing carbon blocks made from coke or pitch, or by molding thermosetting resin such as frifuryl alcohol into the shape of a boat, hardening, and firing. has been done.

Products processed from carbon blocks have problems such as the block itself being porous and the processing resulting in a large amount of wasted material.

In methods using condensable thermosetting resins, by-products are generated during the curing process, so it is difficult to make the desired thickness at once, and it is necessary to repeat coating and curing.

OBJECTS OF THE INVENTION The object of the present invention is to easily produce a container made of impermeable vitreous carbon.

Structure and operation of the invention The present invention is a method of hardening a container such as a boat or crucible made by laminating sheets of cellulose paper, cloth, etc. impregnated with a thermosetting resin, and then firing it in a non-oxidizing atmosphere. This is a method of making it into a container.

The resin may be impregnated by forming a container from a sheet of cellulose material, such as paper, and then impregnating the container with the resin, or by impregnating paper with the resin and then processing it into the shape of a container.

When processing containers into containers, resin-impregnated cardboard can be used if the container is shallow, such as on a boat.
It is difficult to impregnate resin in a sufficiently uniform manner with cardboard, and in order to suppress the air permeability, it is preferable to use a stack of thin resin-impregnated papers in this case. In the case of resin-impregnated containers, it is also preferable to use a laminated container in which the containers are successively made smaller and the entire stack is crimped. Lamination increases denseness.

In the present invention, a carbon filler such as carbon (including graphite) powder or fiber can also be included in the material constituting the container. If these amounts are too large, impermeability will be impaired, so the content is preferably 40% by weight or less. In the case of powder, 74 μm or less is suitable. The method for incorporating it is to mix carbon filler into sheets of paper, cloth, etc. from cellulosic materials, or to disperse carbon fine powder or microscopic carbon fibers in resin liquid, and then to make sheets of paper, etc. A method of impregnating it with water may also be used.

Phenol resin, furan resin, etc. are used as the thermosetting resin, and these are diluted with acetone, ethanol, etc., and used after adjusting the viscosity. Impregnation into paper or the like is carried out by dipping or coating the paper, cloth, or container in the resin liquid. The amount of resin to be impregnated is suitably 30 to 70 parts by weight based on 100 parts by weight of the total amount of cellulose fibers and carbon filler, excluding the diluent. Even if the resin content is extremely small or too large, pores are likely to occur.

The thermosetting resin mentioned above includes various derivatives such as phenolic resin. For example, phenolic resins modified with drying oils such as tung oil and linseed oil are preferred examples. In the case of this modified resin, the decomposition and gas generation during the firing process are slow, so firing is easy.

The resin-impregnated container is then cured and fired. It is necessary to carry out the firing gradually, especially when the temperature is raised from 230 to 360°C, and preferably 1.5°C/hr or less. The subsequent firing is preferably carried out in a non-oxidizing atmosphere at a temperature increase rate of about 5 to 10°C/hr.
The appropriate firing temperature is 800°C or higher, but graphitization treatment may be performed if necessary. Since the laminated tube is made of thermosetting resin during firing, it will not lose its shape and can be fired as is. The tube shrinks considerably during firing, so this must be taken into consideration when molding.

In the present invention, the cellulose fiber is carbonized and becomes one with the carbonized resin, but unlike other synthetic fibers, the cellulose fiber does not fuse with the resin and lose its fiber form, so it has a reinforcing effect. is large. Moreover, the inclusion of fibers facilitates the decomposition of resin and other gases during the firing process, and prevents the formation of pores in the product.

Example 1 The size of pot-shaped containers made of kraft paper was gradually reduced so that they could be stacked on top of each other.
I prepared 10 pieces. This was impregnated with resin by dipping it into a solution of phenolic resin diluted with acetone and having a viscosity of about 50 cps. After drying the respective containers, they were stacked one on top of the other and were pressurized and heated in a mold. The laminated container after molding had an outer diameter of 5 cm, a height of 10 cm, and a wall thickness of 2 mm. This was heated to 150°C in 1 hour and held for 1 hour to cure. Next, the temperature was raised to 1000°C in a nitrogen atmosphere for 100 hours to complete carbonization.

The characteristics of this container are as follows.

Wall thickness Air permeability Bending strength 1.4 mm 3×10 ^-8 cm ² /sec 1300 Kg/cm ² Example 2 A phenolic resin partially modified with tung oil was used as the thermosetting resin. 100 parts tung oil and 150 parts phenol
1 part and 50 parts of nonylphenol were mixed and kept at 50°C. Add 0.5 parts of sulfuric acid to this, stir, and gradually raise the temperature and hold at 120°C for 1 hour to carry out an addition reaction between tung oil and phenol.

After that, the temperature was lowered to below 60℃, and 6 parts of hexamethylenetetramine and 100 parts of 37% formalin were added.
After reacting at 90°C for about 2 hours, the mixture was dehydrated in vacuum and diluted with 100 parts of methanol and 100 parts of acetone to obtain a varnish with a viscosity of 20 eps.

100 parts by weight of this varnish and 10% fine graphite powder (44 μm or less)
The weight part was added as the binder.

Kraft paper was immersed in this binding material solution, pulled up, dried, and stacked with 20 sheets. Next, use the deep drawing method to a depth of 10
A boat with tapered sides measuring 10 cm in length and 2 cm in width was molded.

This was cured and fired in the same manner as in Example 1. Its characteristics are as follows.

Wall Thickness Air Permeability Bending Strength 2.1mm 2×10 ^-8 cm ² /sec 1500Kg/cm ^2Effects of the Invention According to the present invention, the carbide of cellulose and the carbide of resin become one body, exhibiting a glass-like shape, and Gas can escape easily during carbonization of the resin, and in the end, a container with extremely few pores and excellent air impermeability and impermeability can be obtained. Therefore, it is suitable as a container for handling molten materials such as various metals and salts. Moreover, the manufacturing method is extremely easy compared to conventional methods.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a carbon container, which comprises curing a container constructed by laminating cellulose sheets impregnated with a thermosetting resin and firing the container in a non-oxidizing atmosphere. 2. A method for manufacturing a carbon container according to claim 1, wherein the container material contains a carbon filler.