JPH10194836A - Production of glassy carbon material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the mold releasability of a molded body, to reduce strain in the molded body, to narrow the density distribution of the molded body and to obtain a glassy carbon material having narrow density distribution and almost free from microprores by curing a thermosetting resin mixed with a water-soluble salt and carrying out firing. SOLUTION: A mixture is prepd. by mixing at least one kind of thermosetting resin selected from among furan resin, phenolic resin and phenol modified furan resin with 0.0005-0.025mol water-soluble salt based on 1g of the resin. The salt is selected from among alkali metallic salts of org. acids, alkaline earth metallic salts of org. acids and transmission metallic salts of org. acids. The mixture is poured into a mold 1 consisting of a pair of flat plates 2, 3 confronting each other at 0.5-5mm interval and a sealing material 4, the thermosetting resin is cured by heating at 50-90 deg.C for 5-100hr and the resultant molded body 5 is released from the mold 1. A substrate 6 obtd. by working the molded body 5 in a prescribed shape is fired at 1,000-1,500 deg.C for 35-200hr in an inert gaseous atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a glassy carbon product. More specifically, including a recording medium substrate, a magnetic head, a nozzle for fluid ejection, a sliding bearing,
The present invention relates to a method for producing a glassy carbon material that can be suitably used for a material such as a sputtering target.

[0002]

2. Description of the Related Art Conventionally, in order to improve the impact resistance of a substrate for a recording medium represented by a substrate for a hard disk (HD), to reduce the weight by reducing the thickness, and to reduce the motor power consumption by reducing the weight, such a substrate is used. Glass-like carbon (Glass-like Carbon) material having a three-dimensional network structure is used as a material for the above.

The above-mentioned glassy carbon material is produced by curing a thermosetting resin by a condensation reaction in a mold and baking the obtained cured resin (Japanese Patent Publication No. 63-44).
684, JP-B-63-46004).

As a method of manufacturing a recording medium substrate using the glassy carbon material, first, a liquid thermosetting resin such as a phenol-modified furan resin, a phenol resin, and a furan resin is prepared, and the liquid thermosetting resin is prepared. After mixing the thermosetting resin and the curing agent, it is poured into a mold for molding a flat cured resin, and the thermosetting resin is cured in the mold to form a flat cured resin, Next, a cured resin substrate having a central hole corresponding to a predetermined product shape is cut out from the plate-shaped cured resin, and the cured resin substrate is fired in a firing furnace to be carbonized to obtain a glassy carbon material. Lapping with a polisher, grinding the inner and outer peripheral surfaces with a grindstone, polishing with a double-side polisher, etc.
2. Description of the Related Art A method for manufacturing a recording medium substrate made of a glassy carbon material having surface roughness and dimensional accuracy is known.

In the method of manufacturing a recording medium substrate, when a thermosetting resin is cured in a mold, generally,
A method has been adopted in which a liquid thermosetting resin and a curing agent are mixed, degassed under reduced pressure, injected into a mold or vat of a normal pressure release system, and then cured by a condensation reaction.

[0006] However, when the above method is adopted, the thermosetting resin has a disadvantage that it adheres to a resin mold or a metal mold having a particularly high polarity because the thermosetting resin has a high adhesion to a mold material. Therefore, according to the method, a molded article can be obtained according to the mold by curing the thermosetting resin, but it is difficult to release the mold, so that not only productivity is significantly reduced, Upon release from the mold, distortion and density distribution occur in the molded body. Since these strains and density distributions generate density distributions and micropores when the molded body is fired, particularly, for example, a substrate for a hard disk (HD) that requires a high degree of nonporosity is required. This is a major obstacle in stably manufacturing a recording medium substrate to be manufactured.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and has a releasability in removing a molded article obtained by molding a thermosetting resin in a mold. To provide a method for producing a glassy carbon material in which the density distribution and the generation of micropores are reduced by improving strain, thereby improving the productivity and reducing the strain and density distribution generated in the molded body. Aim.

[0008]

The gist of the present invention is a method of producing a glassy carbon material by curing a thermosetting resin and baking the obtained cured resin. Before curing, a salt soluble in water is added to the thermosetting resin in an amount of 0.0005 to 0.025 mol per gram of the thermosetting resin.
The present invention relates to a method for producing a glassy carbon material, which comprises mixing at a ratio of 1.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for producing a glassy carbon material according to the present invention is, as described above, a method for producing a glassy carbon material by curing a thermosetting resin and firing the obtained cured resin. In addition, before curing the thermosetting resin, a salt soluble in water is mixed with the thermosetting resin at a ratio of 0.0005 to 0.025 mol per 1 g of the thermosetting resin.

The thermosetting resin used in the present invention is not particularly limited as long as it can be cured by a condensation reaction. As the thermosetting resin, for example, at least one selected from a furan resin, a phenol resin, and a phenol-modified furan resin can be used.

A typical example of the thermosetting resin is a resin obtained by co-condensing phenol or furfuryl alcohol with formaldehyde or paraformaldehyde.

Specific examples of the thermosetting resin include, for example, a phenol-modified furan resin described in JP-B-63-44684.

In the present invention, the curing agent for the thermosetting resin may be appropriately selected and used according to the type of the thermosetting resin. As an example, when a phenol-modified furan resin is used as the thermosetting resin, a mixture of paratoluenesulfonic acid, water and glycol described in JP-B-63-44684 can be exemplified.

The amount of the curing agent used is not particularly limited, but is usually about 5 parts by weight or less, preferably about 0.2 to 1 part by weight, per 100 parts by weight of the thermosetting resin.

In the present invention, a water-soluble salt is added to the thermosetting resin in an amount of 0.0005 to 1 g per thermosetting resin.
One major feature is that mixing is performed at a rate of 0.025 mol.

Generally, when a thermosetting resin is used,
During the curing of the thermosetting resin, a condensation reaction occurs, in which case water is generated. Since the generated water bleeds out to the interface between the molded body and the mold, the releasability may be given to some extent, but the releasability is insufficient, and depending on the type of the mold material, The releasability may be significantly reduced.

On the other hand, in the present invention, a water-soluble salt is added to the thermosetting resin in an amount of 0.03 g / g of the thermosetting resin.
By adopting the means of mixing at a ratio of 005 to 0.025 mol, the following excellent effects are exhibited.

That is, the thermosetting resin used in the present invention is cured by a condensation reaction, and the amount of water generated at that time is about 10 to 20% by weight based on the cured resin.
Although the generated water bleeds out of the cured resin to some extent, the hardness (Vickers hardness) Hv of the cured resin is 1
Even if the resin is cured to a degree, if it is large, moisture is present in the cured resin as much as about 10% by weight. As the curing of the thermosetting resin progresses, the thermosetting resin becomes more hydrophobic, so that water aggregates and water droplets are formed, and the water droplets form micropores in the cured resin.

However, in the present invention, a water-soluble salt is added to the thermosetting resin in an amount of 0.000 g / g of the thermosetting resin.
A means of mixing at a rate of 5 to 0.025 mol is employed, and such a salt soluble in water becomes a nucleus of water droplets. A glassy carbon material without pores can be stably obtained.

In the present invention, the water generated by the condensation reaction of the thermosetting resin bleeds out to an interface between the cured resin and the mold material to some extent, thereby exhibiting the releasability.
If it is used alone, the releasability is insufficient. Further, the releasability may be significantly reduced depending on the type of the mold material.

However, in the present invention, the releasability is remarkably improved by a synergistic effect of water generated by the condensation reaction of the thermosetting resin and precipitation of the salt dissolved in the water.

As described above, by curing in the presence of a salt, a non-porous molded product can be obtained stably, and the obtained molded product has excellent removability from a mold material. Is greatly reduced. This not only improves the productivity, but also reduces the hardening strain generated inside the molded product, so that cracks and the like are less likely to occur, the molded product yield and the firing yield are improved, and further, the product is obtained by firing. The obtained glassy carbon material is uniform and has a high yield after polishing, so that several excellent properties such as stable quality are exhibited.

In the present invention, the amount of the salt soluble in water per 1 g of the thermosetting resin is set at 0.1 to improve the releasability and to prevent the formation of micropores in the obtained molded article.
0005 mol or more, preferably 0.001 mol or more, more preferably 0.0025 mol or more,
Further, in order to prevent micropores from being generated in the obtained molded article due to the metal contained in the salt, and to prevent metal contamination of the firing furnace and a reduction in polishing yield, 0.025 mol or less, preferably 0.015 mol or less, Preferably 0.01
mol or less.

The water-soluble salt is not particularly limited as long as it is soluble in water. Specific examples of such water-soluble salts include, for example, organic acid alkali metal salts, organic acid alkaline earth metal salts, and organic acid transition metal salts. Such water-soluble salts are used alone or in combination of two or more. Among these, paratoluenesulfonic acid salts, organic acid alkali metal salts having a benzene ring such as paraphenolsulfonic acid salts are excellent in dispersibility in water generated at the time of curing of a thermosetting resin. Is preferably used.

Next, the method for producing the glassy carbon material of the present invention will be described with reference to the drawings.

FIG. 1 shows one embodiment of the method for producing a glassy carbon material of the present invention and the obtained glassy carbon material.
For example, it is a schematic explanatory view showing one embodiment of a method for producing a base material for a recording medium.

In FIG. 1A, reference numeral 1 denotes a mold for molding a thermosetting resin. The mold 1 includes a pair of flat plates 2 and 3 facing each other with a predetermined gap therebetween, and a sealing material 4 for sealing the periphery of the gap between the flat plates 2 and 3.

Examples of the material for the flat plates 2 and 3 include glass, stainless steel, aluminum, and various resins, but the present invention is not limited to the above examples.

Examples of the material of the sealing material 4 include materials such as silicone, vinyl chloride resin and the like, various rubbers and the like which have excellent adhesion to the flat plates 2 and 3 and have low gas permeability. .

The gap between the flat plates 2 and 3 may be appropriately adjusted according to the use of the glassy carbon material and the like, and is not particularly limited, but is usually about 0.5 to 5 mm.

In the gap between the flat plates 2 and 3, as described above,
Usually, a thermosetting resin and a curing agent are mixed, then a water-soluble salt is mixed into the mixture, and the resulting mixed solution may be poured.

Next, the thermosetting resin is cured between the flat plates 2 and 3 to obtain a molded product made of the flat cured resin.

The heating temperature and the heating time for curing the thermosetting resin are not particularly limited, and may be appropriately set according to the type of the thermosetting resin. Usually, the heating temperature is selected from the range of 50 to 90 ° C, and the heating time is selected from the range of 5 to 100 hours.

Next, after the curing is completed, as shown in FIG. 1 (b), a tool, a lathe or the like having a pair of large and small annular cutting blades concentrically arranged from the molded body 5 removed from the mold 1. Thereby, the cured resin substrate 6 having a predetermined final shape is cut out. The cured resin substrate 6 is a disk having a central hole.

Next, the obtained cured resin substrate 6 is placed in a firing furnace, and is heated at a rate of 5 to 30 ° C./hour in an inert gas atmosphere such as nitrogen gas or argon gas.
The temperature is raised to a temperature of about 00 to 1500 ° C. for a desired time,
For example, by carbonizing by baking for about 35 to 200 hours and then cooling, for example, FIG.
The glassy carbon material 7 having the shape shown in (c) can be obtained.

Next, from the glassy carbon material 7, for example,
When manufacturing a recording medium substrate, the glassy carbon material 7 is wrapped with a double-side polishing machine or the like, and the outer and inner peripheral surfaces of the glassy carbon material 7 are ground with a grindstone or the like, and the diameter thereof is reduced. By trimming and chamfering the corners and polishing with a double-side polishing machine or the like, it is possible to obtain a recording medium substrate having the required flatness, surface roughness and dimensional accuracy required for the final product.

[0037]

EXAMPLES Next, the method for producing the glassy carbon material of the present invention will be described based on examples, but the present invention is not limited to these examples.

Production Example 1 A mixture of 470 parts by weight of paraformaldehyde and 190 parts by weight of water was added to 500 parts by weight of furfuryl alcohol, and the mixture was heated to 80 ° C. while stirring.

Next, phenol 67 was added to the obtained mixture.
8 parts by weight of a mixture of 0 parts by weight and 18 parts by weight of calcium hydroxide
After dropwise addition with stirring at 0 ° C, the mixture was aged at 80 ° C for 3 hours, cooled to room temperature, and p-toluenesulfonic acid was added.
H was adjusted to 3-5.

Next, this was added to furfuryl alcohol 500
After dilution with parts by weight, 200 parts by weight of water was dehydrated under reduced pressure of 5 to 25 mmHg at 60 ° C. to obtain a phenol-modified furan resin having a viscosity of 300 cP at 25 ° C. as a thermosetting resin.

Example 1 While stirring the phenol-modified furan resin obtained in Production Example 1, 0.0 g / g of the phenol-modified furan resin was stirred.
Calcium paratoluenesulfonate as a salt soluble in water was added at a rate of 025 mol, and the mixture was thoroughly mixed.
% By weight of a phenol-modified furan resin and 0.5% by weight of a glycol,
It was added in parts by weight.

Next, after the obtained mixture was degassed under reduced pressure, the obtained mixture was placed on two glass plates (400 × 400).
X6mm) to the end of silicone tube (outer diameter 4mm,
(2mm inside diameter) is sandwiched and the sealed effective thickness is 2mm
Cast in the mold.

Next, the mold was placed in a drier under normal pressure and heated at 80 ° C. for 48 hours to carry out a curing reaction.

After the curing was completed, the obtained molded article was demolded. The demolding was very smooth, there was no adhesion of the obtained molded article to the mold material, and cracks occurred in the molded article. Not at all.

Next, the obtained compact was placed in a tubular furnace, heated to 1200 ° C. at a rate of 10 ° C./hour under a nitrogen gas stream, and calcined while maintaining the temperature for 2 hours. Thereafter, the resultant was cooled to obtain a glassy carbon material.

As physical properties of the obtained glassy carbon material,
The occurrence of micropores and the variation in density were examined according to the following methods. Table 1 shows the results.

(1) Generation of Micropores The obtained glassy carbon material was polished with # 3000 SiC abrasive grains and 0.5 μm diamond abrasive grains using a double-side polishing machine, and the micropores per 1 cm ^{2 of} the polished surface were polished. The state of occurrence is observed with an optical microscope (× 100).

(2) Variation in Density In order to evaluate whether or not the obtained glassy carbon material is homogeneous, the density is measured.

With respect to the two obtained glassy carbon materials, the densities at the four corners and the central part (total of 10 points) were measured using a density gradient tube (A-type direct-reading specific gravity measuring device, manufactured by Shibayama Kikai Seisakusho Co., Ltd.). Measure and examine the average and variation.

Example 2 In Example 1, while stirring the phenol-modified furan resin obtained in Production Example 1, a water-soluble salt of p-toluenesulfone was added in an amount of 0.007 mol per 1 g of the phenol-modified furan resin. Acid calcium salt, and stainless steel plate (300 × 3) instead of two glass plates
(00 × 2 mm) A molded article was obtained in the same manner as in Example 1 except that two sheets were used.

After the curing was completed, the obtained molded article was released from the mold. The demolding was very smooth, there was no adhesion of the obtained molded article to the mold material, and cracks occurred in the molded article. Not at all.

Next, the obtained molded body was fired in the same manner as in Example 1 to obtain a glassy carbon material.

As physical properties of the obtained glassy carbon material,
The occurrence of micropores and variations in density were examined in the same manner as in Example 1. Table 1 shows the results.

Example 3 In Example 1, while stirring the phenol-modified furan resin obtained in Production Example 1, a salt soluble in water at a ratio of 0.0035 mol per 1 g of the phenol-modified furan resin was converted to paraphenol sulfone. Acid sodium salt and a stainless steel plate (30
A molded article was obtained in the same manner as in Example 1 except that two sheets (0 × 300 × 2 mm) were used.

After the curing was completed, the obtained molded article was released from the mold. The demolding was very smooth, the resulting molded article did not adhere to the mold material, and cracks occurred in the molded article. Not at all.

Next, the obtained molded body was fired in the same manner as in Example 1 to obtain a glassy carbon material.

As physical properties of the obtained glassy carbon material,
The occurrence of micropores and variations in density were examined in the same manner as in Example 1. Table 1 shows the results.

Example 4 In Example 1, while stirring the phenol-modified furan resin obtained in Production Example 1 while stirring, para-toluene sulfone was dissolved as a salt soluble in water at a rate of 0.013 mol per 1 g of the phenol-modified furan resin. Acid calcium salt, and stainless steel plate (300 × 3) instead of two glass plates
(00 × 2 mm) A molded article was obtained in the same manner as in Example 1 except that two sheets were used.

After the curing was completed, the obtained molded article was released from the mold. The demolding was very smooth, there was no adhesion of the obtained molded article to the mold material, and cracks occurred in the molded article. Not at all.

Next, the obtained molded body was fired in the same manner as in Example 1 to obtain a glassy carbon material.

As physical properties of the obtained glassy carbon material,
The occurrence of micropores and variations in density were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 A molded article was obtained in the same manner as in Example 1, except that no water-soluble salt was used.

After the curing was completed, the obtained molded product was demolded. The obtained molded product adhered to the mold material, and cracks were observed in a part of the molded product.

Next, the obtained molded body was fired in the same manner as in Example 1 to obtain a glassy carbon material.

As physical properties of the obtained glassy carbon material,
The occurrence of micropores and variations in density were examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 A molded article was obtained in the same manner as in Example 2 except that no water-soluble salt was used.

After the curing was completed, the obtained molded article was demolded. However, since the molded article was adhered to the mold material, it took a long time to demold, and most of the molded article was removed. The occurrence of cracks was observed.

Next, the obtained molded body was fired in the same manner as in Example 1 to obtain a glassy carbon material.

As physical properties of the obtained glassy carbon material,
The occurrence of micropores and variations in density were examined in the same manner as in Example 1. Table 1 shows the results.

COMPARATIVE EXAMPLE 3 In Example 1, while stirring the phenol-modified furan resin obtained in Production Example 1, a calcium carbonate salt as a salt almost insoluble in water at a ratio of 0.005 mol per 1 g of the phenol-modified furan resin. And a stainless steel plate (300 × 300 ×
2 mm) A molded article was obtained in the same manner as in Example 1 except that two sheets were used.

After the curing was completed, the obtained molded product was demolded, but the molded product adhered to the mold material, and most of the molded product was broken.

Further, when the cross section is observed, it is found that
m mass of calcium carbonate was generated.

Next, the obtained molded body was fired in the same manner as in Example 1 to obtain a glassy carbon material.

As physical properties of the obtained glassy carbon material,
The occurrence of micropores and variations in density were examined in the same manner as in Example 1. Table 1 shows the results.

[0075]

[Table 1]

From the results shown in Table 1, according to the methods of Examples 1 to 4, the water-soluble salt was dissolved in the thermosetting resin at a ratio of 0.0005 to 0.025 mol per gram of the thermosetting resin. By being used, it is understood that the mold release performance is excellent, the productivity is good, and the obtained glassy carbon material has little cracks and micropores and a small density distribution. .

On the other hand, in the methods of Comparative Examples 1 and 2, the water-soluble salt was not added to the thermosetting resin, so that the mold release performance was poor, the productivity was poor, and the method was obtained. It can be seen that the glassy carbon material has many occurrences of cracks and micropores, and has a large variation in density distribution.

In the method of Comparative Example 3, the use of a water-insoluble salt in the thermosetting resin resulted in poor mold release performance and poor productivity, and the obtained glassy carbon material was It can be seen that many cracks and micropores are generated, and that the density distribution varies greatly.

[0079]

According to the method for producing a glassy carbon material of the present invention, the releasability at the time of demolding a molded article obtained by molding a thermosetting resin in a mold is improved, and thus the production is improved. Since it is possible to improve the properties and reduce the strain and density distribution generated in the molded body, it is possible to produce a glassy carbon material with reduced density distribution and generation of micropores with high productivity. Is played.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one embodiment of a method for producing a glassy carbon material of the present invention.

[Explanation of symbols]

 Reference Signs List 1 mold 2 flat plate 3 flat plate 4 sealant 5 molded body 6 cured resin substrate 7 glassy carbon material

Claims (6)

[Claims] 1. A method for producing a glassy carbon material by curing a thermosetting resin and baking the obtained cured resin, wherein the thermosetting resin is cured before the thermosetting resin is cured. Water-soluble salt per 1 g of thermosetting resin
A method for producing a glassy carbon material, comprising mixing at a rate of from 0.05 to 0.025 mol. 2. The method for producing a glassy carbon material according to claim 1, wherein a salt soluble in water is mixed with the thermosetting resin at a ratio of 0.001 to 0.015 mol per 1 g of the thermosetting resin. 3. The method for producing a glassy carbon material according to claim 1, wherein a salt soluble in water is mixed with the thermosetting resin at a ratio of 0.0025 to 0.01 mol per 1 g of the thermosetting resin. 4. An alkali metal salt of an organic acid, wherein the salt soluble in water is
The method for producing a glassy carbon material according to any one of claims 1 to 3, which is an organic acid alkaline earth metal salt or an organic acid transition metal salt. 5. The method for producing a glassy carbon material according to claim 1, wherein the thermosetting resin is at least one selected from a furan resin, a phenol resin, and a phenol-modified furan resin. 6. The method for producing a glassy carbon material according to claim 1, wherein the thermosetting resin is obtained by co-condensing phenol or furfuryl alcohol with formaldehyde or paraformaldehyde.