JP2000239335A - High-density cured spherical phenolic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cured spherical phenolic resin having high density and containing little nitrogen. SOLUTION: The cured spherical phenolic resin has a specific gravity of 1.20-1.35 measured by a gas-substitution process using helium gas as a medium and a nitrogen content of <=0.5 wt.%. It can be produced by reacting phenol with formaldehyde in the presence of an alkali catalyst and curing the product using an acid catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a high-density spherical phenol resin cured product. Further, the nitrogen content in the cured product is 0.5% or less, and it is possible to obtain a carbon material with almost no generation of a nitrogen-containing compound during carbonization and firing. Therefore, it can also be used in the field of carbon materials.

[0002]

2. Description of the Related Art Conventionally, various methods have been known for synthesizing a spherical cured product of a phenol resin. JP-A-57-177
No. 011 discloses a method of synthesizing a spherical cured product by adding phenol to a solution obtained by heating hydrochloric acid, which is a strong acid, and formalin. However, this method cannot provide a spherical cured product having a small particle size. Also, even if a cured product is obtained, since hydrochloric acid is used during the reaction,
A chlorine ion removing step is required, but it is very difficult to completely remove the chlorine ions, and it remains at a concentration of several thousand ppm in the cured product particles.

Further, Japanese Patent Application Laid-Open No. Sho 62-2351212 discloses a method for obtaining a cured spherical phenol resin by adding hexamethylenetetramine and a suspension stabilizer to a novolak type phenol resin. It is possible to produce a cured product having a particle size from the particle size to about 1000 μm. However, when curing this spherical cured product, hexamethylenetetramine, which is a nitrogen source, must be used, and nitrogen atoms are taken into the cured product. At present, hexamethylenetetramine is used as a cured product in the synthesis of most spherical cured products. At present, there is almost no report on a method of obtaining a spherical cured product containing almost no nitrogen.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been completed as a result of various studies to obtain a cured spherical phenolic resin in which pores are hardly formed inside the particles, and has been completed. You can also get things. In recent years, phenolic resins have attracted attention as a carbon material precursor, but it is desirable that they do not contain a nitrogen-containing compound that becomes a volatile component during carbonization. This is because when burning in the post-treatment step, it goes out of the system as nitrogen oxides, so that it is necessary to provide a treatment device.

[0005]

According to the present invention, a specific gravity measured by a gas replacement method using helium as a medium is 1.20 to 1.3.
5 is a cured spherical phenolic resin having a nitrogen content of 0.5% by weight or less. The cured product of the spherical phenolic resin of the present invention is obtained by reacting phenols and aldehydes with an alkaline catalyst to synthesize a phenolic resin containing a methylol group, and is cured using an acid catalyst such as oxalic acid for curing. By reacting
A high-density spherical phenol resin cured product is obtained. By performing the curing reaction in the presence of a suspension stabilizer, a good spherical cured product can be obtained.

If an attempt is made to obtain a cured product directly with an acid catalyst without using an alkali catalyst from the initial stage of the reaction between the phenol and the aldehyde, it takes a very long time to cure, and the shape is not perfectly spherical but irregular. You can only get things. First, the reaction rate of phenol is improved by forming a resole resin with an alkali catalyst, and as a result, the yield as a resin is higher than that of the case of using an acid catalyst alone. In addition, the sphericity tends to increase as the amount of the methylol group increases.

[0007] The obtained spherical cured product has a specific gravity of 1.2 to 1.3 as measured by using helium as a medium gas. Since the specific gravity of a general phenol resin is 1.25, it was presumed that the internal structure had almost no voids. In fact, when a cross-sectional photograph of the inside was taken with an electron microscope, the voids were hardly confirmed, and even if they existed, the voids were partially present in the center.

[0008] In the alkaline catalyst used in the present invention,
Hydroxides, oxides, carbonates and the like of alkali metals such as sodium, potassium and lithium; barium, calcium,
Hydroxides, oxides, carbonates and the like of alkaline earth metals such as magnesium; triethylamine and the like, which have many methylol groups and are catalysts for producing highly polar phenolic resins. The amount of these catalysts is from 0.01 to 30% by weight, preferably from 1 to 20% by weight, based on phenol. If it is less than 0.01% by weight, a spherical phenol resin cannot be obtained. Further, if it is more than 30% by weight, the effect on the reaction does not change, and the amount of addition becomes excessive.

The control of the density of the spherical cured product depends on the amount of the acid catalyst used during the curing reaction, that is, the pH. The lower the pH, the higher the density of the spherical cured product tends to be. As the catalyst used in the curing reaction, it is preferable to use an organic acid such as oxalic acid or acetic acid. Although a spherical cured product can be obtained by using a mineral acid such as hydrochloric acid, sulfuric acid, and nitric acid, the subsequent washing step is complicated. Also, the acid cannot be completely removed. When hexamethylenetetramine is used, a spherical cured product containing nitrogen is obtained, and a target nitrogen content of 0.5% by weight or less cannot be obtained.

[0010] One method of controlling the particle size is to adjust the amount of the suspending agent. In order to obtain a spherical cured product of 0.1 to 2000 μm, the amount is usually 10
It is 200 to 1.5 parts by weight with respect to 00 parts by weight. Suspending agents to be added include, for example, gum arabic, gum tragacanth, alginates, carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, polyvinyl alcohol, polyvinyl butyral, polyethylene glycol, polyphosphate, polyethylene oxide, and the like, alone or in combination of two or more. You may use together.

The phenols used in the production of the cured spherical phenolic resin used in the present invention include phenol, orthocresol, metacresol, paracresol, xylenol, catechol, resorcinol, alkylphenols,
Bisphenols and the like, which may be used alone or in combination of two or more, are not particularly limited thereto. Examples of the aldehydes include formaldehyde, paraformaldehyde, benzaldehyde, and the like, or a substance serving as a source of these aldehydes, or a solution of these aldehydes, and these may be used alone or in combination of two or more. It is not particularly limited to these.

The reaction molar ratio (ratio of aldehydes / phenols) is 0.85 to 5% when preparing a cured spherical phenolic resin.
3.00 is preferred. Those reacted under the condition that the reaction molar ratio is less than 0.85 may not be cured sufficiently.
On the other hand, when the molar ratio exceeds 3.00, the formalin odor during production is intense. It is preferable to use only water as the reaction solvent. The use of an organic solvent requires wastewater treatment in the post-reaction step and should be avoided.

At the time of production of the cured spherical phenol resin, aromatic hydrocarbons,
Metals, modified with materials that can be carbon materials, pigments,
Other polymers such as lubricants, antistatic agents and antioxidants may be added.

[0014]

The present invention will be described below with reference to examples. However, the present invention is not limited by the examples. Further, “parts” and “%” shown in Examples and Comparative Examples are all “parts by weight” and “% by weight”.

Example 1 In a 5 L three-necked flask equipped with a stirrer, a reflux condenser and a thermometer, 1000 parts of phenol, 1300 parts of a 37% formaldehyde aqueous solution, 1500 parts of water, 30 parts of triethylamine, and gum arabic as a suspending agent were used. Insert 100
Heated to ° C. Forty minutes after the temperature reached 100 ° C., 50 parts of oxalic acid were added, and a reflux reaction was further performed at 100 ° C. for 4 hours. Then, the mixture was washed with water three times and filtered.
After drying for 2 hours, cured spherical phenol resin 1
000 parts were obtained. The particle size distribution of the obtained granular cured product, cross-sectional observation using an electron microscope, specific gravity measurement using helium as a medium, and elemental analysis were performed to determine the nitrogen content. FIG. 1 shows a cross-sectional observation photograph of the cured product.

Example 2 A reaction was carried out in the same manner as in Example 1 except that the catalyst was changed to 50 parts of a 50% aqueous sodium hydroxide solution. FIG. 2 shows a cross-sectional observation photograph of the cured product.

Example 3 A reaction was carried out in the same manner as in Example 1 except that 1000 parts of phenol, 1725 parts of a 37% aqueous formaldehyde solution, 20 parts of triethylamine and 5 parts of gum arabic were used. FIG. 3 shows a cross-sectional observation photograph of the cured product.

Example 4 The procedure was repeated except that 1000 parts of meta-cresol, 1300 parts of a 37% aqueous formaldehyde solution, 1500 parts of water, 30 parts of a 50% aqueous sodium hydroxide solution and 5 parts of gum arabic were used.
The reaction was carried out in the same manner as in Example 1. FIG. 4 shows a cross-sectional observation photograph of the cured product.

Example 5 1000 parts of phenol, 1200 parts of 37% formalin,
1600 parts of water, 30 parts of a 50% aqueous sodium hydroxide solution and polyvinyl alcohol (Kurarepovar PVA11)
7) 50 parts were added and a reflux reaction was performed at 100 ° C. Forty minutes after the start of reflux, 50 parts of oxalic acid was added, and the reaction was further performed for 4 hours. A cross-sectional photograph is shown in FIG.

Comparative Example 1 1000 parts of novolak type phenol resin (Sumitomo Durez)
3000 parts of water and 90 parts of PR-51470).
The temperature was raised until the temperature reached ℃. After the temperature reached, 10 parts of gum arabic was added and mixed, and then 50 parts of hexamethylenetetramine was added, and the temperature was raised to 100 ° C.
A reflux curing reaction was performed for 4 hours. The steps after drying were performed in the same manner as in Example 1. Fig. 6 shows a cross-sectional observation photograph of the cured product.
Shown in

Comparative Example 2 1000 parts of phenol, 37% formaldehyde 130
0 parts, 1500 parts of water, 30 parts of triethylamine and 3 parts of gum arabic were added and the temperature was raised to 100 ° C. Thereafter, a reflux reaction was performed for 4 hours. The steps after washing and drying were performed in the same manner as in Example 1 below. FIG. 7 shows a cross-sectional observation photograph of the cured product.

Comparative Example 3 A reaction was carried out in the same manner as in Example 1 except that 1500 parts of phenol, 1800 parts of 37% aqueous formaldehyde solution, 500 parts of water, 30 parts of triethylamine and 50 parts of polyvinyl alcohol were used. FIG. 8 shows a cross-sectional observation photograph of the cured product.

Table 1 shows the evaluation results of Examples 1 to 4 and Comparative Examples 1 to 3. From Table 1 and each figure, Examples 1 to 4
The cured spherical phenol resin obtained in Comparative Examples 1 to 3
It can be seen that this is a high-density spherical cured product as compared with the spherical cured product indicated by. The cured product had a very low nitrogen content.

Table 1 Results of evaluation of cured spherical phenolic resin Average particle size (μm) Specific gravity Nitrogen content (%) Example 1 700 1.27 0.3 Example 2 800 1.23 0.0 Example 3 720 1 .25 0.3 Example 4 650 1.28 0.0 Example 5 100 1.30 0.0 Comparative Example 1 600 1.20 2.5 Comparative Example 2 700 1.09 0.3 Comparative Example 3 100 0 .96 0.0

[0025]

As is clear from the above description, the cured spherical phenolic resin of the present invention can be easily formed into a spherical cured product having a high density and a nitrogen content of 0.5% by weight or less without going through complicated steps. Was obtained. The above-described cured high-density spherical phenolic resin can be used as a catalyst carrier, a carbon material, and a filler.

[Brief description of the drawings]

FIG. 1 is a cross-sectional photograph of the cured phenolic resin obtained in Example 1 by an electron microscope.

FIG. 2 is a cross-sectional photograph of the cured phenolic resin obtained in Example 2 taken by an electron microscope.

FIG. 3 is a cross-sectional photograph of the cured phenolic resin obtained in Example 3 by an electron microscope.

FIG. 4 is a cross-sectional photograph of the cured phenolic resin obtained in Example 4 by an electron microscope.

FIG. 5 is a cross-sectional photograph of the cured phenolic resin obtained in Example 5 by an electron microscope.

FIG. 6 is a cross-sectional photograph of the cured phenolic resin obtained in Comparative Example 1 taken by an electron microscope.

FIG. 7 is a cross-sectional photograph of the cured phenolic resin obtained in Comparative Example 2 taken with an electron microscope.

FIG. 8 is a cross-sectional photograph of the cured phenol resin obtained in Comparative Example 3 taken by an electron microscope.

Claims (4)

[Claims] 1. A cured spherical phenolic resin having a specific gravity of 1.20 to 1.35 measured by a gas replacement method using helium as a medium and a nitrogen content of 0.5% by weight or less. . 2. The cured spherical phenolic resin according to claim 1, which is obtained by reacting phenol and formaldehyde with an alkali catalyst and then performing a curing reaction with an acid catalyst. 3. The cured spherical phenolic resin according to claim 1, which is obtained by reacting by suspension polymerization at a molar ratio of formaldehyde / phenol of 0.85 to 3.0. 4. The spherical phenol resin cured product according to claim 1, wherein the average particle diameter is 0.1 to 2000 μm.