JP3226237B2 - Method for producing cured phenolic resin particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel method for producing cured phenolic resin particles. More specifically, the present invention relates to a method for efficiently producing cured phenol resin particles useful as a filler for lightweight molded articles or as a raw material for activated carbon or carbon material.

[0002]

2. Description of the Related Art There are various conventional methods for producing cured phenolic resin particles, for example, (1) a method of reacting a phenol with a large excess of formaldehyde in the presence of a large amount of an acid catalyst (Japanese Patent Application Laid-Open No. 57-1770011). No.),
(2) A method is known in which a novolak resin and formaldehyde are reacted in an acidic medium in the presence of an emulsion stabilizer (JP-A-62-235312).

[0003] However, the cured phenolic resin particles obtained by these methods are generally colored, are easily darkened with time, and take a long time to produce, resulting in poor productivity and low production cost. It has the disadvantage of being expensive. In the method (1), the operation is complicated and a large amount of an acid catalyst is used. Therefore, not only is it necessary to install an expensive corrosion-resistant reaction tank, but also the production cost associated with waste liquid treatment is large. With the drawback that climbing is inevitable.

On the other hand, recently, there has been a strong demand for the appearance of a filler having a lower bulk specific gravity in order to reduce the weight of molded articles in the molding industry. However, it is difficult to obtain such a filler by the above-mentioned method. It is.

[0005]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides a cured product having a low bulk specific gravity, desirably no coloring, or a pale color which is hardly darkened even when left for a long period of time. An object of the present invention is to provide a method for easily producing phenol resin particles in a short time.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on a method for obtaining a cured phenol resin in the form of particles, and as a result, a liquid phenol resin having a methylol group and an organic ester, preferably a dispersion medium In the presence, by reacting in a dispersed state, it is possible to obtain cured phenolic resin particles of low bulk specific gravity, further by controlling the amount of the alkaline metal compound contained in the liquid phenolic resin, very little coloring, and long The inventors have found that hardened phenol resin particles that are hardly darkened even after being left for a long period of time can be easily obtained, and have completed the present invention based on this finding.

That is, the present invention provides a method for producing cured phenolic resin particles, which comprises reacting a liquid phenolic resin having a methylol group with an organic ester in a dispersed state, preferably in the presence of a dispersion medium. It is.

The liquid phenol resin having a methylol group used in the method of the present invention includes, for example, a novolak resol obtained by adding a methylol group to a resole type, an ammonia resol type, a benzyl ether type or a novolak type phenol resin having a methylol group. It refers to a liquid phenol resin represented by a mold (hereinafter, simply referred to as a liquid phenol resin), and is generally used as an easily usable aqueous solution. Such a liquid phenol resin can be prepared by reacting a phenol or a novolak type phenol resin with an aldehyde in the presence of a basic catalyst or an acidic divalent metal salt catalyst. For ammonia resol-type and benzyl ether-type liquid phenol resins using divalent metal salts as catalysts, from the viewpoint of reactivity with organic esters, alkali metal compounds, especially alkali metal compounds, are treated after the reaction to complete the reaction. Is desirable.

The amount of the alkaline metal compound contained in the above-mentioned liquid phenolic resin depends on the reaction conditions selected for the reaction with the organic ester, for example, whether or not heating, the type of the liquid phenolic resin and the organic ester, and the mixing ratio thereof. Although it is not determined unconditionally because it is determined according to, it is generally 0.1 equivalent or more, preferably 0.6 equivalent or more with respect to 1 equivalent of the phenolic hydroxyl group of the phenol used at the time of preparing the liquid phenol resin. It is. The upper limit of the use amount is usually about 1.5 equivalents mainly from an economic viewpoint, but is not limited thereto. In particular, cured phenolic resin particles (hereinafter referred to as cured particles)
According to the unexpected relationship between the hue of the above and the amount of the alkaline metal compound used, in order to obtain light-colored cured particles, as described above, 0.1 to 1 equivalent of the phenolic hydroxyl group of the phenol is used.
It is desirable to use at least 8 equivalents, and to obtain cured particles with extremely little coloration, at least 1.0 equivalent, preferably at least 1.0 equivalent.
It is desirable to use at a ratio of .about.1.5 equivalents.

Examples of the phenols used for preparing the liquid phenol resin include phenol, cresol, xylenol, butylphenol, resorcinol, catechol, bisphenol A, bisphenol F, phenol purification residue, bisphenol A purification residue, and the like. However, the present invention is not limited to this. On the other hand, examples of the aldehydes include, but are not limited to, formalin, paraformaldehyde, trioxane, glyoxal, and furfural. These may be used alone or in combination of two or more. The amount (molar ratio) of the aldehyde to the phenol is selected in consideration of the reactivity with the organic ester and the economic efficiency.
To 6.0, preferably selected in the range of 1.0 to 4.0. Examples of the basic catalyst include, for example, alkali metal compounds such as potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium phosphate, sodium carbonate, sodium hydrogen carbonate, calcium hydroxide, barium hydroxide, magnesium oxide, and oxides. Examples thereof include alkaline metal compounds such as alkaline earth metal compounds such as calcium, and amine compounds such as triethylamine, ammonia, and hexamine. Further, as the acidic divalent metal salt catalyst, for example, zinc acetate, lead acetate, manganese acetate,
Examples include, but are not limited to, zinc chloride, lead naphthenate, cobalt naphthenate, and the like. These may be used alone or in combination, or both may be used in combination.

[0011] The liquid phenolic resin may be, if necessary,
For example, γ-aminopropyltriethoxysilane, N-β
(Aminoethyl) γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β
A silane coupling agent such as-(3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxyethoxy) silane, and γ-mercaptopropyltrimethoxysilane may be contained. Further, depending on the purpose of use, for example, aniline, melamine, urea, epoxy resin, melamine resin, urea resin, vinyl acetate resin, polyamide resin,
It may be modified with a vinyl chloride resin, a fluorine resin, a polyacetal resin, a silicon resin, an emulsion rubber or the like.

The organic ester used in the present invention is an ester compound having a function as a curing agent for a liquid phenol resin, and specifically includes, for example, methyl formate, ethyl formate, propyl formate, methyl acetate, and oxalate. Carboxylic acid esters such as dimethyl acid, diacetin, triacetin, ethylene glycol monoacetate, ethylene glycol diacetate, γ-butyrolactone, γ
Lactones such as -caprolactone, δ-valerolactone, δ-caprolactone, β-propiolactone, ε-caprolactone, ethylene carbonate, propylene carbonate, 4-ethyldioxolone, 4-butyldioxolone, 4,4- Examples include, but are not limited to, alkylene carbonates such as dimethyldioxolone and 4,5-dimethyldioxolone. Among these, formate esters and γ-butyrolactone, which exhibit particularly excellent reaction activity, are preferred. These may be used alone or in combination of two or more. The amount of such an organic ester used depends on the type of the liquid phenol resin and the organic ester, the reaction rate, the presence or absence of heating, the hue of the cured particles,
Since it is determined in consideration of economical efficiency and the like, it is not specified unconditionally, but is generally 0.1 equivalent or more, preferably 0.5 equivalent or more, relative to 1 equivalent of the alkali metal compound in the liquid phenol resin. It is preferably at least 1.0 equivalent.

In an embodiment of the present invention, the liquid phenol resin and the organic ester are, for example, put into a reaction vessel at one time and reacted while being mixed by a mechanical stirrer or an ultrasonic homogenizer. While stirring the organic ester, there may be mentioned a method in which a liquid phenol resin is continuously or dividedly charged therein and reacted, but preferably, the liquid phenol resin is stirred and dispersed in a dispersion medium in advance. After that, an organic ester is charged and reacted. Alternatively, the two components may be reacted by spraying them into the air and bringing them into contact. The dispersion medium referred to here is a non-reactive liquid and has a property of suspending and dispersing a liquid phenol resin. Examples of suitable dispersion media include hexane, pentane, cyclohexane, benzene, toluene, xylene, and chloride. Examples include, but are not limited to, methylene, chloroform, carbon tetrachloride, and the like. In the case of a liquid phenol resin having a low affinity for water, water may be used as a dispersion medium. These may be used alone or in combination of two or more. In the reaction between the liquid phenol resin and the organic ester,
If necessary, a known surfactant or protective colloid which is effective for promoting the formation of particles and stabilizing the formed particles can be used. Suitable examples of such surfactants include nonionic surfactants such as polyethylene glycol alkyl ether, polyethylene glycol alkyl aryl ether, polyethylene glycol fatty acid ester, sorbitan fatty acid ester, and alkanolamide. Suitable protective colloids include water-soluble polymer compounds such as polyvinyl alcohol, carboxymethylcellulose, hydroxyethylcellulose, and gum arabic. They are,
Each may be used alone or in combination, or both may be used in combination.

The reaction between the liquid phenolic resin and the organic ester is usually carried out at normal temperature, but may be carried out by heating to an appropriate temperature if necessary. The reaction time varies depending on the type of the reactants, the mixing ratio, the presence or absence of the dispersion medium, and the like, but is generally about 3 to 180 minutes. Next, the cured particles formed by the reaction are subjected to water washing and acid neutralization as necessary, then separated by solid-liquid separation means such as filtration or centrifugation, and dried by drying means such as air drying or heat drying. In some cases, heat treatment may be further performed to a desired degree of hardening to obtain hardened particles. Another embodiment of the present invention is, for example, a method in which a liquid phenol resin and an organic ester are mixed in advance, and the mixture is granulated and cured by a spray method or a rotating desk method.

The cured particles thus obtained have a low bulk specific gravity, and in some cases, have very little coloring, or are pale and hard to darken, and have a high proportion of fixed carbon even when sintered at high temperatures. Since it has properties such as remaining, it can be used in fields where such properties are required, especially as lightweight fillers such as molding materials and casting materials, or as raw materials for activated carbon and carbon materials.

[0016]

In the method of the present invention, since a reaction mode in which the reaction rate is usually extremely high is employed, the generation of coarse particles due to complexation in the reaction process is small, and cured particles having a uniform particle size can be obtained. In particular, when a liquid phenol resin having a high degree of hydrophilicity is used, the cured particles generated are in a state of high water content, so that it is easy to form a porous internal structure by drying, and the cured particles are lighter than the conventional production method. Obtainable. In addition, when a liquid phenol resin containing a specific amount of an alkaline metal compound is used, it is possible to obtain hardened particles that are very little colored, or are light-colored and hardly darken even when left for a long period of time.

[0017]

Next, the present invention will be described in more detail by way of examples, which should not be construed as limiting the present invention.

Incidentally, the bulk specific gravity of the obtained cured particles is 300
The volume after tapping of 50 g of the cured particles charged into the cc measuring cylinder was measured, and the weight was obtained by dividing 50 g by the volume. The hue was visually determined.

Example 1 980 g of phenol was placed in a four-necked reaction flask equipped with a thermometer, a stirrer, a cooling condenser and a dropping funnel.
After 600 g of a 40% by weight aqueous sodium hydroxide solution (0.6 equivalent / 1 equivalent of phenolic hydroxyl group) was charged, 1276 g of 47% by weight formalin was continuously added dropwise with stirring. After completion of the dropwise addition, the temperature was raised to 70 ° C., and the reaction was carried out at the same temperature for 3 hours. After the completion of the reaction, 734 g of water was added, and a 40% by weight aqueous solution of an alkaline resol-type phenol resin (hereinafter, referred to as “resin type”)
Resin liquid A). Then 3 equipped with a stirrer
1000 g of toluene as a dispersion medium in a liter reaction vessel
And 1 g of a polyethylene glycol alkyl ether-based nonionic surfactant, and then, with stirring, 300 g of the resin liquid A was added to form resin particles.
Subsequently, γ-butyrolactone 108 was used as an organic ester.
g (2.5 equivalents / alkali metal compound 1 equivalent) was added and reacted at room temperature for 40 minutes to cure the resin particles. At this time, the reaction solution turned from deep red to pink after 20 minutes. Then, the cured particles were separated by a centrifuge,
Washed and dried. The obtained cured particles are pale pink,
The bulk specific gravity was 0.38. When this was left outdoors in a sealed translucent container for one month, no discoloration was observed.

Example 2 980 g of phenol was placed in the same reaction flask as in Example 1.
And 1000 g of a 40% by weight aqueous sodium hydroxide solution (1
(Equivalent / one equivalent of phenolic hydroxyl group), and 1276 g of 47% by weight formalin was continuously added dropwise with stirring. After completion of the dropwise addition, the temperature was raised to 70 ° C., and the reaction was carried out at the same temperature for 3 hours. After completion of the reaction, 734 g of water was added to obtain a 40% by weight aqueous solution of an alkaline resol-type phenol resin (hereinafter, referred to as a resin solution B). Next, 1000 g of toluene previously heated to 50 ° C. as a dispersion medium and 1 g of a polyethylene glycol alkylaryl ether-based nonionic surfactant were added as a dispersion medium in the same reaction vessel as in Example 1, and then the resin was stirred. 300 g of the liquid B was charged to form resin particles in toluene. Subsequently, 194 g (3 equivalents / 1 equivalent of an alkali metal compound) of γ-butyrolactone was charged as an organic ester and reacted at 50 ° C. for 10 minutes to cure the resin particles. At this time, the reaction solution changed from dark red to light pink after 2 minutes, and became almost white after 10 minutes. Next, the cured particles were separated by a centrifuge, washed with water and dried. The obtained cured particles exhibited a hue almost white, and the bulk specific gravity was 0.36.
When this was left outdoors in a sealed translucent container for one month, no coloring was observed.

Example 3 Bisphenol A9 was placed in the same reaction flask as in Example 1.
12g, 1236g of 22% by weight aqueous sodium hydroxide solution
(0.85 equivalent / 1 equivalent of phenolic hydroxyl group), 840 g of 47% by weight formalin was continuously added dropwise. After completion of the charging, the temperature was raised to 70 ° C., the reaction was continued at the same temperature for 2 hours, and then cooled. Next, 373 g of a 30% by weight aqueous sodium hydroxide solution (0.35 equivalents / one equivalent of phenolic hydroxyl group) and 234 g of water are added, and the mixture is thoroughly stirred and mixed. ) Got. next,
After the same reaction vessel used in Example 1 was charged with 1000 g of γ-butyrolactone as an organic ester (14.5 equivalents / one equivalent of an alkali metal compound) and 1 g of a polyethylene glycol alkylaryl ether-based nonionic surfactant, While stirring, 300 g of the resin liquid C was added to form resin particles and reacted at room temperature for 20 minutes to cure the formed particles. At this time, the reaction solution changed from dark red to light pink after 5 minutes, and then gradually became pale and almost white. Next, the cured particles were separated by a centrifugal separator, washed with water and dried.
The obtained cured particles had a hue almost white, and the bulk specific gravity was 0.34. When this was put in a sealed translucent container and left outdoors for one month, no discoloration was observed.

Example 4 980 g of phenol was placed in a 3 liter three-necked reaction flask equipped with a thermometer, a stirrer and a cooling condenser.
After charging 705 g of 85% by weight paraformaldehyde and 0.98 g of zinc acetate, the mixture was heated to 100 ° C. with stirring and reacted at the same temperature for 60 minutes. Subsequently, the temperature was raised to 120 ° C. while distilling off water, and the reaction was carried out at the same temperature for 120 minutes. After completion of the reaction, the reaction mixture is cooled, 1000 g of a 40% by weight aqueous sodium hydroxide solution (1.0 equivalent / 1 equivalent of phenolic hydroxyl group) and 1405 g of water are added, and a 40% by weight aqueous solution of an alkaline benzyl ether type phenol resin (hereinafter referred to as resin liquid D). ) Got. Next, 1000 g of toluene and 1 g of a polyethylene glycol alkylaryl ether-based nonionic surfactant were added as a dispersion medium in the same reaction vessel as in Example 1, and the resin solution D was stirred.
300 g were charged to form resin particles. Subsequently, 100 g of γ-butyrolactone and 90 g of methyl formate as organic esters (3.6 equivalents / 1 equivalent of alkali metal compound)
Was charged and reacted at room temperature for 40 minutes to cure the resin particles. At this time, the reaction solution changed from dark red to pale pink after 5 minutes, and then gradually became pale and almost white. Then, the cured particles were separated by a centrifuge,
Washed and dried. The obtained cured particles exhibited a hue almost white, and the bulk specific gravity was 0.36. When this was left outdoors for one month in a sealed translucent container, no discoloration was observed.

COMPARATIVE EXAMPLE 1 In a 3 liter three-necked reaction flask equipped with a thermometer, a stirrer and a cooling condenser, 800 g of a novolak type phenol resin (melting point: 70 ° C.), 37% by weight formalin 1
After charging 80 g, water 800 g and gum arabic 20 g, agitate and mix to granulate and raise the temperature to 96 ° C., add 300 g of a 3% by weight hydrochloric acid aqueous solution, and further react at the same temperature for 3 hours to produce particles. Cured. Next, the cured particles were separated by a centrifugal separator, and were washed with water and dried. The resulting particles are yellow-brown and have a bulk specific gravity of 0.1.
It was 5. Also, place this in a sealed translucent container for 1 hour.
When left outdoors for months, it turned brown. Table 1 summarizes the results of the above examples and comparative examples.

[0024]

[Table 1]

As is clear from Table 1, the cured particles (Examples 1 to 4) produced by the reaction of the liquid phenol resin having a methylol group of the present invention with an organic ester are:
The cured particles were found to be extremely pale in color as compared with the cured particles produced using the acid catalyst (Comparative Example 1), hardly colored or discolored even when left for a long time, and had a low bulk specific gravity.

[0026]

As described above, according to the method of the present invention, unlike the conventional method, a long and high-temperature heating reaction in the granulation step is not required, so that the production efficiency and the energy cost are reduced. This is extremely advantageous and can greatly reduce the manufacturing cost. Moreover, there is no need to provide an expensive corrosion-resistant reaction apparatus, and an advantage that an existing reaction tank can be used can be provided. In addition, the obtained cured phenolic resin particles are much lighter than those of the conventional method and are less likely to change color over time, and have a low bulk specific gravity, for example, for a molding material or a casting material that emphasizes weight reduction or hue of a molded product. It is useful as a filler or as a raw material for activated carbon or carbon material.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-49-35491 (JP, A) JP-A-49-40392 (JP, A) JP-A-3-174428 (JP, A) JP-A-60-1985 108434 (JP, A) JP-A-62-235312 (JP, A) JP-A-59-6208 (JP, A) JP-A-5-23785 (JP, A) JP-B-46-147 (JP, B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 8/00-8/38 C08L 61/04-61/16 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. A method for producing cured phenol resin particles, comprising reacting a liquid phenol resin having a methylol group with an organic ester in a dispersed state. 2. The method for producing cured phenolic resin particles according to claim 1, wherein the reaction is carried out in the presence of a dispersion medium.