JP2000256431A - Preparation of low-density globular phenol resin cured product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a low-density globular phenol resin cured product wherein pores are formed inside the particles, without using any solvent, strong acid, etc. SOLUTION: In the preparation process of a globular phenol resin cured product, a phenol is reacted with an aldehyde in an aqueous medium in the presence of a basic catalyst and a suspending agent, wherein, the reaction temperature of suspension polymerization is from 80 to 160 deg.C, and the pH at the beginning of suspension polymerization is from 8.0 to 10.0. Preferably, the molar ratio of the phenol to the formaldehyde during suspension polymerization is from 0.85 to 3.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cured product of a low-density spherical phenol resin, in which the amount of porosity in the resin can be adjusted and the weight can be reduced. For this reason, it can be used as a filler, and since it is a porous material, it is easy to diffuse water vapor and the like into the inside, so that it can be used in the field of activated carbon materials.

[0002]

2. Description of the Related Art Various methods have been employed for producing spherical cured products of phenolic resins. JP-A-62-23
No. 5312, a spherical cured product of a phenol resin is manufactured. However, the spherical cured product obtained by this method is a nonporous material, and is a production method in which a porous phenol resin cannot be obtained. The cured product uses a curing agent such as hexamethylenetetramine or ammonia at the time of curing. Therefore, a nitrogen content remains in the cured product.

As a method for obtaining a porous spherical phenol resin cured product, a method of reacting by adding an insoluble organic solvent to water during suspension polymerization, as described in JP-A-4-59806. In this method, removal of the organic solvent becomes a problem. In addition, when the spherical cured product is dried in a subsequent step, an odor is generated, and new equipment is required to remove the odor, which complicates the manufacturing process.

[0004] It is also possible to synthesize a spherical cured product of a phenolic resin by the method disclosed in Japanese Patent Application Laid-Open No. 57-177001. However, although this method can obtain a spherical cured product having a relatively small particle size of about 20 μm,
It is difficult to obtain a spherical cured product having a particle size exceeding 500 μm. In addition, a large amount of hydrochloric acid, which is a strong acid, is used during the reaction. For this reason, chlorine ions cannot be easily removed in a later step and remain at a level of several thousand ppm.

[0005]

SUMMARY OF THE INVENTION The present invention provides a method for producing a low-density spherical phenol resin cured product in which pores are formed inside particles, and enables control of the amount of pores. is there. Further, from the viewpoint of the process, it is an object of the present invention to produce a low-density cured spherical phenol resin without using a solvent or a strong acid.

In order to achieve the above object, the present inventors have conducted intensive studies, and as a result, reacted phenols and aldehydes in a water solvent with a basic catalyst, and directly reacted in the presence of a suspending agent. It has been found that by curing, a low-density cured spherical phenolic resin is formed. Since this method does not use a strong acid such as hydrochloric acid and does not use hexamethylenetetramine as a curing agent, it is possible to produce a cured product containing almost no nitrogen in the cured spherical phenolic resin. Only when a tertiary amine catalyst is used as the catalyst, the nitrogen content contained in the catalyst is incorporated into the spherical cured product, but it is still 0.5% by weight or less.

[0007]

According to the present invention, the reaction temperature of suspension polymerization is 8 when the reaction of phenols and aldehydes is carried out in an aqueous medium in the presence of a basic catalyst and a suspending agent.
0 to 160 ° C., and the pH value at the start of suspension polymerization is 8.0.
To 10.0, a method for producing a cured spherical phenolic resin.

[0008] By such a method, usually 0.1 ~
It is possible to obtain a cured spherical phenol resin having pores of 30 μm, a density measured by a gas replacement method using helium as a medium of 0.50 to 1.27 g / cm ³ , and a particle size of 1 to 1000 μm. it can. Since the density of a general phenol resin is 1.28 g / cm ³ according to the above measurement method, it was expected that the inside had a porous structure. In fact, when a cross-sectional photograph of the inside of the cured product was taken with an electron microscope, many pores were present. When the size of the internal pore is measured from a cross-sectional photograph, the size is 0.1 to 30 μm.

[0009] A porous, low-density phenolic resin is
In order to obtain the resin without using an organic solvent, as a typical method, it is preferable to synthesize a spherical cured product from a resolated resin by suspension polymerization. Since the methylol group of resole is hydrophilic, it is easy to take in water, and the phenol resin is cured while taking in water, and then water is released out of the system of the cured product. The novolaked phenolic resin is more hydrophobic than resol, and thus has a structure in which moisture is hardly taken in. Therefore, it is difficult to obtain a low-density spherical cured product.

[0010] The method of controlling the density of the cured product is usually carried out by the reaction temperature and / or pH. When controlling by the reaction temperature, the reaction temperature is usually 80 to 160.
° C, preferably 100 to 150 ° C. As the reaction temperature is increased, a low-density spherical cured product is obtained. However, when the reaction temperature exceeds 150 ° C., the curing reaction is accelerated, and rapid gelation may occur, which makes it difficult to obtain a spherical cured product. On the other hand, when the reaction temperature is lower than 80 ° C., the reaction rate becomes slow and the curing of the outer shell of the particles proceeds slowly, so that it is difficult to obtain a spherical cured product having internal pores. Density 1.0g / cm
^In order to obtain a cured product of a low-density spherical phenolic resin having a density of ³ or less, the reaction is preferably performed at a temperature of 110 to 150 ° C.

When controlling the density by pH,
The pH value is preferably from 8 to 10. Particularly preferably 8.1.
８8.8. When the same catalyst is used, the higher the pH, the lower the density of the cured product. When the pH value exceeds 10, the water solubility of the resole increases, and it may be difficult to obtain a spherical cured product. Conversely, if the pH value is less than 8,
The progress of the reaction slows down, and it is difficult to obtain a low-density spherical cured product. Examples of the basic catalyst include hydroxides, oxides, and carbonates of alkali metals such as sodium, potassium, and lithium, and hydroxides, oxides, and carbonates of alkaline earth metals such as barium, calcium, and magnesium. And triethylamine, which has many methylol groups and is a catalyst for producing a highly polar phenol resin. The pH value is also changed by the molar ratio of aldehydes to phenols (hereinafter referred to as reaction molar ratio) and / or the total amount of phenols and aldehydes and the ratio of water to water (hereinafter referred to as reaction material / water ratio). You can do it.

The reaction molar ratio is preferably from 0.85 to 3.00, particularly preferably from 1.3 to 2.0. When the reaction is performed under the condition that the reaction molar ratio is less than 0.85, it takes time to cure. Conversely, if it exceeds 3.00,
The formalin odor increases during production, which may cause a problem in the working environment. Reaction material / moisture ratio is 30 to 70 to 70
A ratio of 30 (weight ratio) is preferred. Particularly preferably, the ratio is 50:50 to 65:35 (weight ratio). If the ratio of the reaction material and the water content is less than the above range, it becomes difficult to obtain a spherical cured product having internal pores. Conversely, if the amount exceeds the above range, suspension polymerization becomes difficult, a spherical cured product is hardly obtained, and gelation may occur in the whole container. Usually, the pH value varies depending on the combination of the type and amount of the catalyst, the molar ratio of the reaction, and the ratio of the reaction material and the water content. Therefore, the reaction can be performed in an appropriate combination depending on the target density.

The cured spherical phenol resin also has the advantage that the particle size can be easily adjusted from a small particle size to a large particle size. The particle size is usually controlled by the amount of the suspending agent. The amount of the suspending agent varies depending on the type, but is usually used in the range of 0.1 to 300 parts by weight based on 1000 parts by weight of the phenol. Within this range, the average particle size is 1 to 1000 μm
Is obtained. The particle size also changes depending on the shape of the stirrer, the number of rotations, the shape of the reactor, and the like. As a suspending agent, for example, gum arabic, gum tragacanth, alginate, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, polyvinyl butyral, polyethylene glycol,
Examples thereof include polyphosphates and polyethylene oxides, and they may be used alone or in combination of two or more.

The phenols used for producing the cured spherical phenol resin used in the present invention include phenol, meta-cresol, xylenol, catechol, resorcinol,
Alkylphenols, bisphenols and the like, and these may be used alone or in combination of two or more.
It is not particularly limited to these. 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. Usually, only water is used as the reaction solvent. This is because the use of an organic solvent necessitates waste liquid treatment in the post-reaction step.

[0015]

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 1000 parts of phenol, 1463 parts of 37% formalin, 133 parts of water, 133 parts of water and 20 parts of triethylamine were placed in a 10-liter pressure reactor (autoclave) equipped with a stirrer and a thermometer.
Part and polyvinyl alcohol as a suspending agent (Kurarepovar PVA117, saponification degree 98%, polymerization degree 1700)
9 parts, 150 ° C., 0.1 rpm at a stirring rotation speed of 120 rpm.
The reaction was performed for 5 hours. The pH value in the system before the start of the suspension polymerization was 8.5. Thereafter, the obtained resin was taken out of the reactor, washed three times with water, filtered, and dried at 80 ° C. for 12 hours to obtain a cured spherical phenol resin.

Example 2 Example 1 except that the reaction conditions were 120 ° C. and 1.5 hours.
In the same manner as in the above, a spherical phenol resin cured product was obtained. FIG. 1 shows a cross-sectional photograph of the cured spherical phenol resin by a scanning electron microscope (hereinafter, referred to as SEM).

Comparative Example 1 Example 1 was repeated except that the reaction conditions were 180 ° C. and 0.5 hours.
Was performed in the same manner as described above. After the completion of the reaction, the entire inside of the reactor was gelled, and a granular hardened product could not be obtained.

Example 3 A 10-L reactor equipped with a stirrer, a reflux condenser and a thermometer was charged in the same manner as in Example 1, and the stirring rotation speed was 120 rpm.
At 100 ° C. for 5 hours. After the completion of the reaction, the same post-treatment as in Example 1 was performed to obtain a cured spherical phenol resin.

Example 4 The same apparatus and the same charge as in Example 3 were used and the stirring rotation speed was 12
The reaction was performed at 0 rpm at 90 ° C. for 10 hours. After the completion of the reaction, the same post-treatment as in Example 1 was performed to obtain a cured spherical phenol resin.

Comparative Example 2 The same procedure as in Example 3 was carried out except that 5 parts of triethylamine as a catalyst was used. At this time, the pH value in the system before the start of suspension polymerization was 7.7. No granular cured product was obtained.

Example 5 1000 parts of phenol and 1123% of 37% formalin were placed in a 10 L reactor equipped with a stirrer, a reflux condenser and a thermometer.
Parts, water 277 parts, triethylamine 17 parts and polyvinyl alcohol (Kurarepovar PVA11) as a suspending agent.
7, saponification degree 98%, polymerization degree 1700) 10 parts,
The reaction was performed at 100 ° C. for 5 hours at a stirring rotation speed of 120 rpm. The pH value in the system before the start of suspension polymerization was 8.3. After the completion of the reaction, the same post-treatment as in Example 1 was performed to obtain a cured spherical phenol resin.

Example 6 1000 parts of phenol and 37% formalin 1463 were placed in a 10 L reactor equipped with a stirrer, a reflux condenser and a thermometer.
Parts, 133 parts of water, 20 parts of triethylamine and polyvinyl alcohol as a suspending agent (Kurarepovar PVA11).
7, saponification degree 98%, polymerization degree 1700), and reacted at 100 ° C. for 5 hours at a stirring rotation speed of 60 rpm.
The pH value in the system before the start of the suspension polymerization was 8.5. After the completion of the reaction, the same post-treatment as in Example 1 was performed to obtain a cured spherical phenol resin. FIG. 2 shows a cross-sectional photograph of the cured spherical phenol resin by SEM.

Example 7 1000 parts of phenol, 1725 parts of 37% formalin,
A cured sphere resin was obtained in the same manner as in Example 6, except that 20 parts of a 50% aqueous sodium hydroxide solution and 5 parts of polyvinyl alcohol were used. FIG. 3 shows a cross-sectional photograph of the cured spherical phenol resin by SEM.

Comparative Example 3 1000 parts of phenol and 37% formalin 1465 were placed in a 10 L reactor equipped with a stirrer, a reflux condenser and a thermometer.
Parts, water 1425 parts, triethylamine 30 parts and polyvinyl alcohol as a suspending agent (Kurarepovar PVA1).
17, saponification degree 98%, polymerization degree 1700), 10 parts were added, and the mixture was reacted at 100 ° C. for 5 hours at a stirring rotation speed of 120 rpm. The pH value in the system before the start of suspension polymerization was 8.4. After the completion of the reaction, the same post-treatment as in Example 1 was performed to obtain a cured spherical phenol resin. FIG. 4 shows a cross-sectional photograph of the cured spherical phenol resin by SEM.

Comparative Example 4 1000 parts of phenol, 1200 parts of 37% formalin,
Except that 1600 parts of water, 50 parts of oxalic acid and 5 parts of gum arabic were used, the same procedure as in Example 6 was carried out to obtain a cured spherical phenol resin. SEM of this spherical phenol resin cured product
FIG. 5 shows a cross-sectional observation photograph by the method.

With respect to the cured spherical phenol resin obtained in each of the examples and comparative examples, the average particle diameter and the density using helium as a medium were measured. Table 1 shows the results.

Table 1 Results of Evaluation of Cured Spherical Phenol Resin Average Particle Size (μm) He Density (g / cm ³ ) Example 1 160 0.57 Example 2 157 0.85 Example 3 105 1.13 Example 4 152 1.23 Example 5 105 1.25 Example 6 584 0.92 Example 7 680 1.04 Comparative Example 3 96 1.28 Comparative Example 4 700 1.28

From Table 1, the cured phenolic resin obtained in the examples shows that the measured He density is lower than the general phenolic resin density of 1.28 g / cm ³ . It was confirmed that the cured product was a low-density spherical cured product.

[0030]

As is apparent from the above description, the cured spherical phenolic resin obtained by the present invention is a low-density spherical cured product having a porous internal structure and can be produced without going through a complicated process. it can. Further, by changing the reaction temperature, the pH value and the amount of the suspending agent, it is possible to produce a spherical cured product having various particle diameters and an arbitrary density. The low-density spherical cured product obtained by the present invention can be used as a filler, a carrier for a catalyst, and a carrier for various adsorbents. And, since there is almost no nitrogen content in the cured product and the amount of the generated nitrogen-containing compound during carbonization is low, it can be used as a precursor for activated carbon.

[Brief description of the drawings]

FIG. 1 is an SEM of a spherical cured product obtained in Example 2.
Cross section photograph.

FIG. 2 is an SEM of the spherical cured product obtained in Example 6.
Cross section photograph.

FIG. 3 is an SEM of the spherical cured product obtained in Example 7.
Cross section photograph.

FIG. 4 is an SEM of the spherical cured product obtained in Comparative Example 3.
Cross section photograph.

FIG. 5 is an SEM of the spherical cured product obtained in Comparative Example 4.
Cross section photograph.

Claims (5)

[Claims] 1. A reaction between a phenol and an aldehyde,
When the reaction is carried out in an aqueous medium in the presence of a basic catalyst and a suspending agent, the reaction temperature of the suspension polymerization is from 80 to 160 ° C, and the pH at the start of the suspension polymerization is from 8.0 to 10.0. A method for producing a cured spherical phenolic resin, characterized in that: 2. The obtained spherical phenol resin cured product,
It has pores of 0.1 to 30 μm inside and has a density of 0.50 to 1.27 measured by a gas replacement method using helium as a medium.
g / cm ^3, and a manufacturing method of claim 1 spherical phenol resin cured product according particle sizes of 1 to 1000 m. 3. The method for producing a cured spherical phenolic resin according to claim 1, wherein the molar ratio of the aldehyde to the phenol during the suspension polymerization is 0.85 to 3.0. 4. The hardened spherical phenolic resin according to claim 1, wherein the ratio of the total amount of phenols and aldehydes to water at the time of suspension polymerization is 30 to 70 to 70 to 30 (weight ratio). Method of manufacturing a product. 5. The pH value is adjusted by adjusting the kind or amount of the basic catalyst, the molar ratio of aldehydes to phenols, and / or the ratio of the total amount of phenols and aldehydes to water. 5. The method for producing a spherical phenol resin cured product according to claim 3, 3 or 4.