JP2001287988A - Vitrified carbon and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-quality vitrified carbon having very small amount of developed defects and having homogeneous dense organization structure. SOLUTION: This vitrified carbon is characterized by <=300/25 cm2 total number of the defects by SEM measurement (at 1,000 magnification) in the vitrified carbon obtained by molding a resin composition for the vitrified carbon, consisting essentially of a thermoset resin, curing the thermoset resin, and firing and carbonizing the cured resin in an inert atmosphere or in vacuum. The method for producing the vitrified carbon is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to glassy carbon and a method for producing the same. More specifically, the present invention has very few defects as compared with the prior art. And a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Vitreous carbon has a vitreous dense structure, gas impermeability, abrasion resistance, corrosion resistance, self-lubricating property, surface smoothness, and the like. Due to its excellent properties such as non-contamination and robustness, it has been put to practical use in various applications such as semiconductor applications such as plasma etching electrodes and recording media such as hard disks.

[0003] Such a glassy carbon is usually produced by molding a thermosetting resin such as a phenol resin and carbonizing and firing a molded product obtained by curing the same. If gas, decomposition gas, solvent, etc. remain in the form of fine bubbles, they will be damaged during carbonization and firing, and the resulting glassy carbon will have many defects (pores).
This causes a decrease in gas impermeability, material strength, oxidation resistance, and the like. For this reason, various measures for reducing the occurrence of defects have been conventionally proposed.

For example, an acid catalyst having an acidity (PKa) of 0 to 1 is added as a curing agent to a thermosetting resin precondensate, and the mixture is subjected to primary curing under reduced pressure at room temperature, and then to secondary curing by heating. There has been proposed a method for producing glassy carbon capable of removing condensed water and decomposed gas generated during a curing reaction by firing and carbonizing in an inert atmosphere (Japanese Patent Publication No. 4-55122). There has been proposed a method for producing glassy carbon in which pores can be reduced by adding a dispersant to a thermosetting resin to disperse condensed water (Japanese Patent Application Laid-Open No. 7-82028). A molded product obtained by molding and curing a thermosetting resin is carbonized and fired in an inert atmosphere at a temperature of 800 ° C. to 1000 ° C. under atmospheric pressure, and then 1 torr.
The following method for producing a glassy carbon material which is carbonized and fired at 1200 ° C. to 2000 ° C. in a reduced-pressure inert atmosphere or under vacuum has been proposed (Japanese Patent Application Laid-Open No. 8-133715).
Prior to molding, there has been proposed a method for producing glassy carbon in which a thermosetting resin liquid as a raw material is flowed as a thin film flow on an inclined surface in a vacuum vessel held in a decompression system to perform a defoaming treatment in advance (particularly). JP-A-7-300306). HIP (Ho
A method has been proposed in which pores in a carbon material are isotropically crushed and densified by t-isostatic-pressing (hot isostatic pressing) treatment (Japanese Unexamined Patent Publication No. Sho 63-2).
79078).

However, in the above methods (1) to (4), a certain amount of condensed water, decomposed gas, solvent and the like can be removed, but none of them can completely remove condensed water, decomposed gas, solvent and the like. There is a problem in that the glassy carbon obtained by carbonization has a defect, and cannot be used for a semiconductor application such as a plasma etching electrode, which particularly dislikes a defect, and a recording medium such as a hard disk. In addition, the above-described method requires an expensive HIP processing apparatus, resulting in an increase in cost, and also has a problem that a control operation of a high-temperature and high-pressure gas is complicated.

As described above, all of the conventional methods for producing glassy carbon have advantages and disadvantages, and are not capable of efficiently and at a low cost obtaining a sufficiently satisfactory high-quality glassy carbon. Was desired.

The present invention has been made in view of the above circumstances, and provides a high-quality vitreous carbon having very few defects compared to the prior art, having an excellent homogeneous and dense texture structure, and this vitreous carbon efficiently. An object is to provide a method for manufacturing at low cost.

[0008]

Means for Solving the Problems and Embodiments of the Invention The present inventors have made intensive studies to achieve the above object, and as a result, have found that a resin composition for glassy carbon containing a thermosetting resin as a main component has been obtained. After being molded and cured, in a glassy carbon obtained by calcining and carbonizing in an inert atmosphere or under vacuum, the glassy carbon obtained by performing the curing before the above calcining under reduced pressure or under vacuum has defects. Very little,
It was found that it had a homogeneous and dense tissue structure.

That is, a resin composition for glassy carbon containing a thermosetting resin as a main component is molded, cured, and then calcined and carbonized in an inert atmosphere or under vacuum. By performing the previous curing under reduced pressure or vacuum, the resin solvent, condensed water generated during the resin curing reaction, the reaction product gas, the solvent and the like can be efficiently removed from the system, and the obtained glassy carbon Total number of defects by SEM measurement (magnification 1000 times) is 300/2
5 cm ² or less, which is extremely small as compared with the conventional one, and high-quality glassy carbon having an excellent homogeneous and dense structure can be obtained. Particularly, semiconductor defects such as plasma etching electrodes, and internal defects such as recording media such as hard disks. The present invention was found to be most suitable for applications that do not like the occurrence of water, and the present invention was accomplished.

Further, according to the method for producing glassy carbon of the present invention, by performing thermosetting under reduced pressure or vacuum before calcining and carbonizing, a resin solvent, condensed water and decomposition gas generated in the thermosetting reaction, Solvents and the like can be efficiently and forcibly removed from the system, and these do not become fine bubbles and remain in the cured product, and the occurrence of defects can be prevented as much as possible. No control operation is required, and high-quality glassy carbon can be efficiently produced at low cost.

Accordingly, the present invention firstly comprises molding and curing a resin composition for glassy carbon containing a thermosetting resin as a main component, followed by firing and carbonizing in an inert atmosphere or under vacuum. In glassy carbon, the total number of defects of the above glassy carbon determined by SEM measurement (magnification: 1000 times) is 300/25 cm ² or less. After molding and curing the glassy carbon resin composition to be,
In a glassy carbon obtained by calcining and carbonizing in an inert atmosphere or under vacuum, the glassy carbon is obtained by performing the above-mentioned curing before calcining under reduced pressure or under vacuum, and In a method of producing a glassy carbon by molding and curing a resin composition for glassy carbon containing a curable resin as a main component, and then curing the resin composition in an inert atmosphere or under vacuum, A method for producing glassy carbon, wherein curing is performed under reduced pressure or vacuum.

Hereinafter, the present invention will be described in more detail. The glassy carbon of the present invention has a total number of defects of 30 by SEM (scanning electron microscope) measurement (magnification: 1000 times).
The glassy carbon is characterized in that the number is not more than 0/25 cm ² , and the glassy carbon is of high quality having a homogenous and dense structure with few defects.

Here, the measurement of the defects (pores) of the glassy carbon in the present invention is performed by cutting a test piece obtained by cutting a glassy carbon having a thickness of 3.0 mm into a square of 5 cm, for example, using an alumina abrasive having an average particle diameter of 0.6 μmm. Polishing (first polishing)
After that, using a scanning electron microscope (SEM), a magnification of 100
Observation is performed at a magnification of 0, and the size and number of surface defects are measured. Further, after the test piece is polished by the above-mentioned alumina abrasive grains by 0.5 mm (second polishing), the size and the number of surface defects are measured in the same manner.

In this case, the total number of defects is 300 / 25c
m ² or less, preferably 200 pieces / 25 cm ² or less, more preferably 100 pieces / 25 cm ^2.
The number is more preferably 50 pieces / 25 cm ² or less, most preferably 30 pieces / 25 cm ² or less. Gas impermeability of glassy carbon obtained if the total number of defects is too large,
Characteristics such as material strength and oxidation resistance decrease.

In the present invention, the size of the defect (the diameter of the defect if it is spherical, and the length of the diagonal line if the defect is angular) is small after satisfying the total number range of defects. Preferably, there is. Especially SEM measurement (magnification 100
(0 times), the size of the defect is 10 μm or less, preferably 5 μm or less, and more preferably 1 μm or less.
In this case, glassy carbon in which the size of the defect is 1 μm or less (50% or more, especially 80% or more) is useful as a substrate of a recording medium such as a hard disk.

Further, the distribution of the size of the defects in the glassy carbon of the present invention is preferably as follows. Defects with a size of more than 10 μm are 0 to 10%, preferably 0 to 5%, more preferably 0%. Defects having a size of 1 to 10 μm are 0 to 30%, preferably 0 to 20%, more preferably 0 to 10%. Defects with a size of less than 1 μm are the remainder.

The glassy carbon of the present invention has the same number and size of defects as those after the first polishing, and the same as those after the first polishing after the second polishing. Preferably, it has a total number and magnitude of defects of the order. That is, it is preferable that the generation of defects is extremely small not only in the vicinity of the surface of the glassy carbon (the first polishing) but also in the inside of the glassy carbon (the second polishing).

Such a glassy carbon of the present invention comprises:
A resin composition for glassy carbon containing a thermosetting resin as a main component is molded and cured, and then calcined and carbonized in an inert atmosphere or under vacuum. It is obtained by performing in.

Here, the thermosetting resin is not particularly limited, but is preferably a carbon source which is converted into glassy carbon by a firing carbonization treatment. For example, furan resin such as liquid resol type phenol resin, phenol resin represented by solid novolak type phenol resin, furfuryl alcohol resin, furfuryl alcohol furfural resin, furfuryl alcohol phenol resin, and polyimide resin Resins, polycarbodiimide-based resins, polyacrylonitrile-based resins, pyrene-phenanthrene-based resins, epoxy-based resins, and derivatives thereof, and the like can be used. One of these can be used alone, or two or more can be used in combination. Among them, a phenolic resin, a furan-based resin, or a mixed resin thereof having a residual carbon ratio of 45% by mass or more when calcined at a temperature of 800 ° C or more in an inert atmosphere such as nitrogen or argon is preferable. When a phenolic resin is used, a curing accelerator such as formaldehyde can be added.

The thermosetting resin is preferably used as a liquid resin by mixing with water or an organic solvent. In this case, the viscosity of the liquid resin at 25 ° C. is 20 Pa · s or less, preferably 0.1 to 1 Pa · s, and the resin concentration is 40% by mass or more, preferably 50% by mass or more in terms of solid content (non-volatile content). It is. Examples of the organic solvent include alcohols such as methanol, ethanol and butanol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; glycols such as ethylene glycol and diethylene glycol; furans such as furan, furfural and furfuryl alcohol; and tetrahydrofuran. (TH
F), N, N-dimethylformamide (DMF), methyl ethyl ketone (MEK), or a mixed solvent thereof with water, and the like. One of these can be used alone, or two or more can be used in combination. Among them, water and a water / alcohol system are preferred from the viewpoint of handleability.

The glassy carbon of the present invention is obtained by curing the resin composition for glassy carbon having the above composition before firing and carbonizing under reduced pressure or vacuum.
In this case, the curing before firing and carbonization is 55 kPa or less, preferably 15 kPa or less, more preferably 10 kPa or less,
More preferably, it is performed under reduced pressure of 3 kPa or less or under vacuum. If the degree of decompression of the curing before calcining exceeds the above range, there is no difference between the prior art and the glassy carbon may have many defects.

The density of the glassy carbon of the present invention is 1.4 to 1.65 g / cm ^{3 as} measured by a density gradient tube.
Preferably, it is 1.48 to 1.58 g / cm ³ , and the density is uniform within an in-plane density difference of 0.01 g / cm ³ .

Next, in the method for producing glassy carbon of the present invention, a resin composition for glassy carbon containing a thermosetting resin as a main component is molded, cured, and then fired in an inert atmosphere or under vacuum. In the method of producing glassy carbon by carbonization, the above-mentioned curing before calcination and carbonization is performed under reduced pressure or vacuum. Here, curing before calcining refers to secondary curing described below, and primary curing performed before secondary curing may or may not be performed under reduced pressure or vacuum. In this case, it is preferable to carry out the curing before calcining under reduced pressure or vacuum of 55 kPa or less.

An example of a specific method for producing glassy carbon is as follows. (1) A liquid glass-like carbon resin composition having a viscosity of 0.3 Pa · s or less (25 ° C.) is filtered using a membrane filter or the like to remove impurities and the like contained in the resin. (2) Using a mold having a desired shape, injecting the filtered resin composition of (1) into the mold, sufficiently degassing under reduced pressure (at least below atmospheric pressure), Remove any entrained air. In this case, the material of the mold to be used is not particularly limited, and an ordinary metal or plastic material can be used. In addition, it is preferable to use a mold that can be opened or closed at least partially so that condensed water, a reaction product gas, a solvent, and the like generated during curing of the resin can be efficiently removed from the system. Further, regardless of the amount of the resin composition injected into the mold, the thickness (depth of the mold) of the resin composition in the mold is 100 mm or less, preferably 30 mm or less. If it is too thick, condensed water, reaction product gas, solvent and the like generated during curing may easily remain in the resin composition. (3) In the thermosetting, first, thermosetting (primary curing) is performed until the resin composition has a hardness (semi-solid state) enough to be taken out of the mold (for example, when methanol is used as a solvent, 40%).
６０60 ° C. for about 40 hours). Next, the obtained semi-solid material is further thermally cured (secondary curing) in a state of being taken out of the mold.
I do. This is because the condensed water, the reaction product gas, the solvent and the like are efficiently removed from the entire periphery of the semi-solid material in the secondary curing step. The primary curing is performed to remove the solvent in the resin and to make the handleable hardness, and it is not particularly necessary to perform under reduced pressure or vacuum,
It may be performed under reduced pressure or under vacuum. (4) Secondary curing is 55 kPa or less, preferably 15 kPa
Pa or less, more preferably 10 kPa or less, still more preferably 3 kPa or less in a reduced pressure atmosphere or under vacuum.
3 ° C./hour or less in a temperature range of 150 ° C., particularly 1 to
It is preferable to carry out the heating at a rate of 3 ° C./hour. On this occasion,
Resin solvent, gas generated during reaction, condensed water, etc. can be thermally cured by maintaining the temperature for a certain period of time in the temperature region where the curing reaction proceeds rapidly according to the type of resin, in the temperature region near the boiling point of the solvent used, etc. From the viewpoint of efficiently removing. (5) The obtained cured resin is heated in an inert atmosphere such as nitrogen or argon in a heating furnace at 800 ° C. or higher at 50 to 500 ° C.
Time, preferably 100-20 ° C at 1200-1500 ° C
Glassy carbon is obtained by carbonizing and firing for 0 hours.

According to the method for producing glassy carbon of the present invention, a resin solvent, condensed water generated in the production process, decomposed gas, a solvent and the like can be efficiently forcibly used without using expensive equipment and simple operations. It can be removed out of the system, and these do not remain in the form of fine bubbles, and the generation of defects can be prevented as much as possible.

The glassy carbon of the present invention has a very small number of defects compared to the prior art, has a uniform and dense structure, and is particularly used for semiconductors such as a plasma etching electrode which does not like the occurrence of internal defects, and a recording medium such as a hard disk. It can be widely used as an electrode for a battery, an electrode for electrolysis, a member for an ion implanter, a base material for a magnetic head, an optical reflection substrate, and the like.

[0027]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1 Phenol resin PL-480
4 [Gunei Chemical Industry Co., Ltd .;
Mass%, viscosity 0.25 Pa · s (25 ° C.)] 200 g was put into a 10 cm square, 30 mm height open stainless steel petri dish, degassed under reduced pressure of 55 kPa, and then heated at 50 ° C. for 40 hours. The resin was thermally cured by heating to a hardness that can be handled (primary curing). Next, the primary cured product was taken out of the mold, and was heated under a reduced pressure of 55 kPa at 70 ° C. for 40 hours and at 100 ° C. for 20 hours under a reduced pressure of 55 kPa.
Thermal curing (secondary curing) was performed at 0 ° C. for 20 hours to obtain a cured resin. The obtained cured resin was fired in an inert atmosphere at a rate of 1 ° C./min to 1200 ° C. to produce the glassy carbon of Example 1. The density of this glassy carbon was 1.54 g / cm ^{3 as} measured by a density gradient tube, and was uniform with an in-plane density difference of 0.01 g / cm ^{3 or} less.

Example 2 The secondary curing was carried out under reduced pressure of 3 kPa at 70 ° C. for 40 hours, at 100 ° C. for 20 hours, and at 150 ° C.
The glassy carbon of Example 2 was prepared in the same manner as in Example 1 except that the reaction was performed for 20 hours. The density of this glassy carbon was 1.54 g / cm ^{3 as} measured by a density gradient tube.
And the uniformity within the in-plane density difference of 0.01 g / cm ³ was obtained.

Example 3 The secondary curing was performed under reduced pressure of 1 Pa.
40 hours at 70 ° C., 20 hours at 100 ° C., 2 at 150 ° C.
A glassy carbon of Example 3 was prepared in the same manner as in Example 1 except that it was performed at 0 hour. The density of this glassy carbon was 1.53 g / cm ^{3 as} measured by a density gradient tube, and was uniform with an in-plane density difference of 0.01 g / cm ^{3 or} less.

[Comparative Example 1] Secondary curing was performed at 70 ° C for 40 hours, 100 ° C for 20 hours, and 150 ° C under a reduced pressure of 65 kPa.
The glassy carbon of Comparative Example 1 was prepared in the same manner as in Example 1 except that the reaction was carried out for 20 hours. The density of this glassy carbon was 1.54 g / cm ^{3 as} measured by a density gradient tube.
And the in-plane density difference was 0.01 to 0.03 g / cm ³ .

[Comparative Example 2] Secondary curing was carried out at atmospheric pressure at 70 ° C.
, And a glassy carbon of Comparative Example 2 was prepared in the same manner as in Example 1 except that the composition was thermally cured at 100 ° C. for 20 hours and at 150 ° C. for 20 hours. The density of this glassy carbon was 1.55 g / cm ^{3 as} measured by a density gradient tube,
The in-plane density difference was 0.01 to 0.04 g / cm ³ .

Comparative Example 3 Phenol Resin PL-480
4 200 g was put in a 10 cm square stainless steel Petri dish with an open top, degassed under reduced pressure of 55 kPa, and then heated at 101 kPa (atmospheric pressure) at 50 ° C. for 40 hours for 7 hours.
40 hours at 0 ° C, 20 hours at 100 ° C, 20 hours at 150 ° C
Heat curing was performed for a time to obtain a resin cured product. The obtained cured resin was fired in an inert atmosphere at a rate of 1 ° C./min to 1200 ° C. to produce glassy carbon of Comparative Example 3. The density of this glassy carbon was 1.55 g / cm ^{3 as} measured by a density gradient tube, and the in-plane density difference was 0.01 to
It was 0.04 g / cm ³ .

Comparative Example 4 Phenol Resin PL-480
4 200 g was placed in a 10 cm square stainless steel Petri dish with an open top, and without degassing, 101 kPa (under atmospheric pressure) at 50 ° C. for 40 hours, 70 ° C. for 40 hours, 10 hours.
The resin was thermally cured at 0 ° C. for 20 hours and at 150 ° C. for 20 hours to obtain a cured resin. The obtained cured resin is placed in an inert atmosphere for 1 hour.
The glassy carbon of Comparative Example 4 was prepared by firing at 1200 ° C. at a temperature rising rate of ° C./min. The density of the glassy carbon is 1.55 g / cm ³ as determined by a density gradient tube was plane density difference 0.01-0.04 / cm ^3.

Next, the obtained Examples 1 to 3 and Comparative Examples 1 to
Cut the glassy carbon of No. 4 into 5 cm squares and polish them with alumina abrasive grains having an average particle diameter of 0.6 μm (the first polishing)
Then, the size and the number of defects were measured by observing at a magnification of 1000 times using an SEM. Further, the glassy carbon after the first polishing was polished by the above-mentioned alumina abrasive grains by 0.5 mm (the second polishing), and the size and number of defects were measured in the same manner. Table 1 shows the results.

[0036]

[Table 1]

[0037]

The glassy carbon of the present invention and the method for producing the same exhibit the following excellent effects. (1) According to the production method of the present invention, the resin solvent, condensed water generated during the reaction, reaction product gas, solvent, etc. are forcibly systemized by performing thermosetting before calcining under reduced pressure or under vacuum. It is possible to obtain high-quality vitreous carbon efficiently and at low cost without special equipment or complicated control operations, as well as being able to be removed outside. (2) Since the resin composition is forcibly exhausted during drying, it is possible to prevent impurities from being mixed into the system. (3) By drying the resin composition under reduced pressure, the boiling point of the solvent is lowered, and a cured resin can be obtained in a shorter time than drying in the air. (4) The glassy carbon of the present invention has a homogeneous and dense texture structure with extremely few defects, and is suitably used particularly for semiconductor applications such as plasma etching electrodes that dislike internal defects and recording media such as hard disks. Can be done.

Claims (7)

[Claims] 1. A glassy carbon obtained by molding and curing a resin composition for glassy carbon containing a thermosetting resin as a main component, and then calcining and firing in an inert atmosphere or under vacuum. SEM measurement of carbon (magnification 10
The glassy carbon is characterized in that the total number of defects due to (00 ×) is 300/25 cm ² or less. 2. The vitreous carbon according to claim 1, wherein the size of the defect in the vitreous carbon determined by SEM measurement (magnification: 1000 times) is 10 μm or less. 3. The glassy carbon according to claim 1, wherein the size of the defect in the glassy carbon measured by SEM (at a magnification of 1000) is as follows. Defects of more than 10 μm: 0 to 10% Defects of 1 to 10 μm: 0 to 30% Defects of less than 1 μm: balance 4. A glassy carbon obtained by molding and curing a resin composition for glassy carbon containing a thermosetting resin as a main component, and then baking it in an inert atmosphere or under vacuum. A glassy carbon obtained by performing the previous curing under reduced pressure or under vacuum. 5. A glassy carbon obtained by molding and curing a resin composition for glassy carbon containing a thermosetting resin as a main component, and then baking it in an inert atmosphere or under vacuum. The vitreous carbon according to claim 1, 2 or 3, which is obtained by performing the previous curing under reduced pressure or under vacuum. 6. A method for producing a glassy carbon by molding and curing a resin composition for glassy carbon containing a thermosetting resin as a main component, followed by firing and carbonizing in an inert atmosphere or under vacuum. A method for producing glassy carbon, wherein the curing before calcining is performed under reduced pressure or vacuum. 7. The method for producing glassy carbon according to claim 6, wherein the hardening before the calcination is performed under reduced pressure of 55 kPa or less or under vacuum.