JP2008101157A - Non-heat meltable granular phenolic resin and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-heat meltable granular phenolic resin which has a fine average particle diameter, does not contain a secondary aggregate, has a sphere particle shape, has a narrow particle size distribution and has a small free phenol content, and its manufacturing method. <P>SOLUTION: The non-heat meltable granular phenolic resin has an average particle size of 20 μm or less and a ratio of single particles of 0.7 or more. Preferably, the non-heat meltable granular phenolic resin has an average particle size of 10 μm or less, a coefficient of variation of the particle size distribution of 0.65 or less, a sphericity of the particles of 0.5 or more, and a free phenol content of 500 ppm or less. The method for manufacturing the non-heat meltable granular phenolic resin comprises a step (1) of reacting an aldehyde with a phenol in the presence of an acidic catalyst and a protective colloid agent in an aqueous medium, a heating step (2) of heating the reaction solution, and a step (3) of separating a granular phenolic resin from the reaction solution to wash the resin, and the molar concentration of the acidic catalyst in the reaction solution is 2.0 mol/L or more. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-heat-meltable granular phenol resin and a method for producing the same. More specifically, it is useful as an organic filler or as a precursor of a functional carbon material such as molecular sieve carbon, and is used in various industrial fields such as molding materials, paints, refractories, papermaking, friction materials, grindstones, and adhesives. The present invention relates to a highly safe non-heat-meltable granular phenol resin and a method for producing the same, which can be suitably used as additives.

  A phenol resin is a material having a good balance between heat resistance, mechanical performance, electrical characteristics, and cost, and is used in various industrial fields. In particular, granular or powdery phenol resins or cured products thereof have recently found applicability in various fields, and some products are already on the market as versatile materials.

  For example, Patent Document 1 discloses a granular or powdered phenol resin cured product composed of a condensate of phenols and formaldehyde, which is trade name “Bellpearl (registered trademark) R type” (Air Water Co., Ltd.). It is commercially available as (made by company). The cured phenol resin is, for example, as an organic filler for imparting heat resistance or improving sliding properties, or as a filler for reducing the amount of gas generated when curing an uncured phenol resin or the like. Useful. Further, since it is a resin having a high residual carbon ratio due to its chemical structure, it is also useful as a calcined precursor of a powdered carbon material suitably used as, for example, activated carbon or a carbon electrode material. Furthermore, the granular or powdery phenol resin cured product described in Patent Document 1 does not contain harmful phenol monomers or low molecular condensation components, and has a feature of high safety.

  Here, when using the granular phenol resin as described above or a cured product thereof as a precursor of an organic filler or a powdered carbon material, in order to exhibit desirable performance as a precursor of an organic filler or a powdered carbon material, The shape and morphology of the particles must be properly controlled. That is, in order to achieve high filling in the product, high specific surface area when used as a powdered carbon material, low viscosity when used as an aqueous slurry, (i) the average particle size of the particles is sufficiently small And (ii) it is necessary that there are almost no secondary aggregates due to aggregation of primary particles. In addition to the above (i) and (ii), it is more desirable that (iii) the particle size distribution of the particles is sufficiently narrow and / or (iv) the shape of the particles is closer to a true sphere. Furthermore, considering the safety of the product to which the granular phenol resin is applied, it is desirable that (v) the residual amount of phenol monomer (free phenol) in the granular phenol resin is smaller. Here, the sufficiently small particle size needs to be at least 20 μm or less, more preferably 10 μm or less, considering application of the granular phenol resin or its cured product to various industrial uses.

  However, although much research has been conducted on the granular phenol resin or its cured product, the granular phenol resin or its cured product having the above characteristics has not been known yet. The present condition is that the manufacturing method suitable for mass production of a phenol resin or its hardened | cured material is also not known.

  For example, in Patent Document 1, a granular or powdered non-heat-meltable phenol resin is obtained by optimizing the synthesis conditions such as the amount ratio of formaldehyde, phenol, hydrochloric acid and aqueous medium used, and the temperature conditions. However, the obtained non-heat-meltable phenol resin has (i) a relatively large primary particle size, (ii) a relatively large number of secondary aggregates formed by aggregation of primary particles, (Iii) The particle size distribution was wide, and (iv) many particles having a shape other than a sphere were included.

  Patent Document 2 discloses a spherical phenol resin cured product obtained by reacting phenol and formaldehyde with an alkali catalyst in the presence of a suspending agent and then performing a curing reaction with an acid catalyst. It is disclosed. However, the average particle size specifically described in the examples is 100 to 800 μm.

  In Patent Document 3, a cellulose compound is added to an initial condensate obtained by reacting phenols and formaldehyde with at least one of an acidic catalyst and a basic catalyst in the presence of a nitrogen-containing compound catalyst, Further, it is described that granulation is performed by continuing the reaction, followed by dehydration and drying to obtain a non-heat-meltable granular phenol resin. However, the average particle diameter of the granular phenol resin is about 700 μm. Moreover, it contains about 6000 ppm of free phenol, and there is room for improvement from the viewpoint of safety.

In Patent Document 4, phenols and aldehydes are condensed in the presence of a condensation reaction catalyst and an emulsifying dispersant under conditions of a temperature of 105 ° C. or higher and 200 ° C. or lower and a pressure of 1.3 kg / cm ² or higher and 15 kg / cm ² or lower. It is described that a spherical phenol resin is obtained by reaction. The spherical phenol resin has an average particle diameter of about 2 to about 200 μm, as in Examples. However, there is a problem that the particle size varies greatly depending on the stirring method and the stirring speed due to the complexity of performing the reaction using an autoclave. Furthermore, the reaction mode is essentially the same as that of Patent Document 3 described above, and the chemical structure of the obtained phenol resin is considered to be equivalent, so that it is thought that it contains a large amount of free phenol.

  Patent Document 5 discloses a spherical form obtained by curing a dispersion of a resol-type spherical phenol resin obtained by reacting phenols and formaldehyde with a nitrogen-containing compound catalyst in the presence of a water-soluble polymer compound with an acidic catalyst. The phenolic resin is described. However, the average particle size of the spherical phenol resin obtained by this method is as large as about 350 to 520 μm.

  Patent Document 6 discloses a method of producing spherical resin fine particles from resorcin and aldehydes, wherein the ratio (weight ratio) of resorcin to water is 1: 5 to 1: 100, and the pH of the reaction system is 5 to 7 There is disclosed a method for producing spherical resin fine particles characterized by adjusting to the above. The spherical resin fine particles have an average particle diameter of 500 nm to 2 μm as in the examples. However, there is a problem that only resorcin can be used as a phenol source, and therefore, the residual carbon ratio of the obtained phenol resin is considered to be low as compared with the case of using other phenols such as phenol.

  In Patent Document 7, a solvent is removed from a homogeneous mixed solution containing a phenol resin, a cellulose derivative, and a solvent to cause phase separation of the phenol resin and the cellulose derivative, the phenol resin is cured, and a phenol resin cured product is then obtained. The manufacturing method of spherical phenol resin hardened | cured material which removes a cellulose derivative from the composite_body | complex of a cellulose derivative is described. By such a method, a spherical phenol resin cured product having an average particle diameter of 28 nm to 5 μm is obtained. However, this method must use an organic solvent which is problematic for the environment and human safety. Furthermore, since the phase separation reaction in the solid phase is used, it takes 21 hours to 114 hours for the generation and extraction of particles.

  In Patent Document 8, a novolak spherical particle precipitated by reacting a phenol compound and formaldehyde in a specific amount of water or a mixed solvent of a water / water-miscible organic solvent in the presence of an acid catalyst while concentrating the solvent. Is disclosed in which a spherical phenol-formaldehyde resin is produced by curing the resin by reaction with a curing agent. According to this method, for example, a spherical phenol resin having a particle size of about 9 μm or 15 μm can be obtained. However, the spherical phenol resin obtained by this method is not sufficiently satisfactory from the viewpoint of particle size distribution. Furthermore, the reaction mode is essentially the same as that of Patent Document 3 described above, and the chemical structure of the obtained phenol resin is considered to be equivalent, so that it is thought that it contains a large amount of free phenol.

  As described above, various methods have been proposed for obtaining phenol resin fine particles, such as using additives such as suspending agents and emulsifying dispersants, and optimizing the polymerization conditions of the phenol resin. The phenol resin particles having an average particle size of 20 μm or less, preferably 10 μm or less, almost no secondary aggregates, a very low content of monomeric phenols, and high safety; No manufacturing method has been proposed. Furthermore, in addition to these characteristics, there has not been proposed a granular phenol resin having a spherical shape and a sufficiently narrow particle size distribution and a method for producing the same.

For example, even when the polymerization conditions for phenol resin are optimized, the polymerization conditions for polymerizing phenols and aldehydes are essentially the same as the polymerization conditions that have been used normally In the obtained phenolic resin, monomer phenols as high as before are contained. In addition, in the method for producing a granular phenol resin in which the stirring speed affects the particle size, the particle size distribution inevitably becomes wide because the inside of the reaction vessel cannot be continuously stirred uniformly.
Japanese Examined Patent Publication No. 62-30210 JP 2000-239335 A Japanese Patent Publication No.53-42075 Japanese Patent No. 3576433 Japanese Patent Publication No. 61-59324 JP 2002-226534 A JP 10-338728 A JP-A-7-18043

  The present invention has been made in view of such a situation. The object of the present invention is that the average particle size is very small, does not contain secondary aggregates, the shape of the particles is spherical, and the narrow particle size. It is to provide a non-heat-meltable granular phenol resin having a distribution, having a low free phenol content and high safety, and a method for producing the same.

  As a result of diligent research, the present inventors have reacted aldehydes and phenols with a high concentration acidic catalyst in an aqueous medium in the presence of a protective colloid agent, and then heated the reaction solution, The present inventors have found that a non-heat-meltable granular phenol resin having the above-mentioned good characteristics can be obtained. That is, the present invention is as follows.

  The non-heat-meltable granular phenol resin of the present invention has an average particle size of 20 μm or less and a single particle ratio of 0.7 or more. The average particle size is preferably 10 μm or less. The definitions of the terms “non-thermal meltability”, “average particle diameter” and “single particle ratio” will be described later.

  In the non-heat-meltable granular phenol resin of the present invention, the variation coefficient of the particle size distribution represented by the following formula [1] is preferably 0.65 or less.

Coefficient of variation of particle size distribution = (d _84% −d _16% ) / (2 × average particle size) [1]
Here, d _84% and d _16% are particle diameters showing cumulative frequencies of 84% and 16%, respectively, in the frequency distribution obtained by the laser diffraction / scattering method.

  Moreover, in the non-heat-meltable granular phenol resin of this invention, it is preferable that the sphericity of particle | grains is 0.5 or more.

  Furthermore, in the non-heat-meltable granular phenol resin of the present invention, the free phenol content is preferably 500 ppm or less. The definitions of the terms “sphericity” and “free phenol content” will be described later.

  The present invention also includes (1) a granular phenol resin forming step in which a granular phenol resin is formed by reacting an aldehyde with a phenol in an aqueous medium in the presence of an acidic catalyst and a protective colloid agent; A heating step of heating the reaction solution containing the granular phenol resin to form a non-heat-melting granular phenol resin, and (3) separating and washing the non-heat-melting granular phenol resin from the reaction solution. A non-heat-meltable granular phenol resin comprising a washing step, wherein the molar concentration of the acidic catalyst in the reaction solution is 2.0 mol / L or more, A method for producing a granular phenolic resin is provided.

  Here, the acidic catalyst is hydrochloric acid, and the aldehyde is preferably formaldehyde, paraformaldehyde or a mixture thereof.

  The molar ratio of the phenols to the aldehydes is preferably 0.9 or less.

The protective colloid agent is preferably a water-soluble polysaccharide derivative.
Furthermore, the present invention provides a non-heat-meltable granular phenol resin obtained by any of the above methods.

  Here, the non-heat-meltable granular phenol resin obtained by any of the above methods preferably has an average particle size of 20 μm or less and a single particle ratio of 0.7 or more. More preferably, the average particle size is 10 μm or less.

  In the non-heat-meltable granular phenol resin obtained by any of the above methods, the coefficient of variation of the particle size distribution represented by the above formula [1] is preferably 0.65 or less.

  Moreover, in the non-heat-meltable granular phenol resin obtained by any of the above methods, the sphericity of the particles is preferably 0.5 or more.

  Furthermore, in the non-heat-meltable granular phenol resin obtained by any of the above methods, the free phenol content is preferably 500 ppm or less.

  According to the present invention, the average particle size is 20 μm or less, and it has a very small particle size and contains almost no secondary aggregates due to the aggregation of the fine primary particles, that is, a high single particle ratio. A hot-melt granular phenolic resin is provided. Such non-heat-meltable granular phenolic resin of the present invention is used as an additive for materials in various industrial fields such as molding materials, paints, refractories, papermaking, friction materials, grindstones, adhesives, and particularly as an organic filler. Or a precursor of a functional carbon material such as a carbon electrode material, activated carbon, or molecular sieve carbon.

  Moreover, this invention provides the manufacturing method suitable for manufacturing the non-heat-meltable granular phenol resin which has the above outstanding characteristics. According to the method for producing a non-heat-meltable granular phenol resin of the present invention, it is possible to produce a non-heat-meltable granular phenol resin having excellent characteristics by a relatively simple method. This method is suitable for mass production.

<Non-heat-melting granular phenolic resin>
The non-heat-meltable granular phenol resin of the present invention is a non-heat-meltable phenol resin comprising a reaction product of phenols and aldehydes, and is a particle (as a term for secondary aggregates, both primary particles and The average particle size is 20 μm or less, and the single particle ratio serving as an index for the content of secondary aggregates is 0.7 or more. Thus, when the average particle diameter of the phenol resin particles is 20 μm or less, preferably 10 μm or less, and the single particle ratio is 0.7 or more, for example, when the granular phenol resin is used as an organic filler, a higher filling rate In addition, the filling material such as a resin composition filled with the granular phenolic resin has a lower viscosity than the conventional one, and thus is easy to handle. The granular phenol resin of the present invention can also be suitably used as a precursor of a functional carbon material such as activated carbon, carbon electrode material, molecular sieve carbon, etc., but the average particle size of the phenol resin particles is preferably 20 μm or less, preferably When the particle size is 10 μm or less and the single particle ratio is 0.7 or more, the space filling property of the carbon powder obtained by firing is greatly improved. Therefore, by using the granular phenol resin of the present invention, the performance per unit volume and the surface area per unit weight of the functional carbon material can be greatly improved. Furthermore, the dispersion liquid in which the functional carbon material obtained from the granular phenol resin of the present invention is dispersed in a liquid medium such as water has a characteristic that it has a low viscosity even in a high concentration region. A dispersion having such characteristics can be suitably used, for example, when a coated carbon electrode is produced. The non-heat-meltable granular phenolic resin of the present invention can be applied not only for the above-mentioned use but also for a wide range of industrial fields such as molding materials, paints, refractories, papermaking, friction materials, grindstones, and adhesives. .

  Here, FIG. 1 shows a scanning electron micrograph (hereinafter referred to as SEM photograph) of a preferred example of the non-heat-meltable granular phenol resin of the present invention. As shown in FIG. 1, the non-heat-meltable granular phenol resin of the present invention is a granular phenol resin having a small particle size, and there are few secondary aggregates due to aggregation of the particles (primary particles). In addition, the granular phenol resin of FIG. 1 has an average particle diameter defined below of 5 μm and a single particle ratio of 1.0.

  Hereinafter, the non-heat-meltable granular phenol resin of the present invention will be described in detail. The non-heat-meltable granular phenol resin of the present invention is a non-heat-meltable phenol resin made of a reaction product of phenols and aldehydes. Here, the reaction product of phenols and aldehydes is basically a product obtained by an addition reaction and a condensation reaction, but also includes a product that has undergone only an addition reaction. . Although it does not specifically limit as phenols, For example, phenol, naphthol, hydroquinone, resorcin, xylenol, pyrogallol etc. can be mentioned. One type of phenol may be used, or two or more types may be used in combination. Especially, when the balance of the performance and cost of the phenol resin obtained is considered, it is preferable that phenols are phenol. The aldehydes are not particularly limited, and examples thereof include formaldehyde, paraformaldehyde, glyoxal, and benzaldehyde. The aldehydes may be used alone or in combination of two or more. Especially, it is preferable that aldehydes are formaldehyde, paraformaldehyde, or these mixtures.

  Here, in the present specification, “non-heat-meltable” means that the granular phenol resin does not fuse under a specific high-temperature pressurization condition. When 5 g is inserted between two 0.2 mm thick stainless steel plates and pre-heated to 100 ° C. and pressed at a total load of 50 kg for 2 minutes, granular phenol is melted and / or fused. It is defined as the property that the resin forms a flat plate, the phenol resin particles are deformed, or the phenol resin particles do not adhere to each other. Such properties can be imparted in the production of a granular phenol resin by synthesizing a phenol resin by a reaction between phenols and aldehydes, and then crosslinking and curing the phenol resin. Crosslinking / curing can be performed, for example, by heating a reaction solution obtained by reacting phenols with aldehydes.

  The boiling methanol solubility of the non-heat-meltable granular phenolic resin of the present invention is preferably less than 30%, more preferably less than 20%. In the present specification, “boiling methanol solubility” means the content of the boiling methanol-soluble component in the granular phenol resin, and is specifically defined as a value calculated by the following test. Specifically, about 10 g of a phenol resin sample was precisely weighed and heated under reflux in about 500 mL of substantially anhydrous methanol for 30 minutes. Filter through 3 glass filter and wash the residue on the glass filter with about 100 mL of anhydrous methanol. Next, the residue on the glass filter after washing is dried at 40 ° C. for 5 hours, and then the residue is precisely weighed. The value calculated by the following formula [2] is defined as “boiling methanol solubility”.

Boiling methanol solubility (% by weight) = (difference between phenol resin sample weight and residue weight after drying) / (phenol resin sample weight) × 100 [2]
“Boiled methanol solubility” is not a direct criterion for determining whether or not the phenol resin has “non-heat meltability”, but can be an index for knowing the degree of heat meltability of the phenol resin. Is. That is, the lower the “solubility of boiling methanol”, the lower the heat melting property. When the boiling methanol solubility is 30% or more, there are cases where the particles exhibit deformation or fusion due to heat melting due to heating or pressurization during use.

  As described above, the average particle size of the particles (primary particles) constituting the non-heat-meltable granular phenol resin of the present invention is 20 μm or less, preferably 10 μm or less. By making the average particle size 10 μm or less, the granular phenol resin of the present invention is further improved in filling properties and low viscosity when applied to organic fillers and functional carbon materials, and low viscosity when applied as a dispersion. can do. Here, in this specification, the “average particle diameter” means a measurement method using a laser diffraction particle size measuring machine, that is, a cumulative frequency of 50% obtained by a laser diffraction / scattering method (microtrack method). Mean value. As a laser diffraction particle size measuring instrument, Microtrac X100 manufactured by Nikkiso Co., Ltd. can be suitably used.

  Moreover, the single particle ratio of the non-heat-meltable granular phenol resin of the present invention is 0.7 or more, preferably 0.8 or more. When the single particle ratio is less than 0.7, the filling property and low viscosity when applied to the organic filler or functional carbon material described above, and the low viscosity when applied as a dispersion are insufficient. There is a tendency. Here, in this specification, “single particles” means primary particles that do not form secondary aggregates due to aggregation, and “single particle ratio” means that granular phenol resin is dispersed in water droplets. The ratio of the total number of primary particles and the number of single particles in a randomly selected visual field including about 300 primary particles is counted, that is, the number of single particles / 1. It means the total number of secondary particles.

  Moreover, it is preferable that the non-heat-meltable granular phenol resin of this invention has a narrow particle size distribution. Specifically, it is preferable that the variation coefficient of the particle size distribution of the particles (primary particles) constituting the non-heat-meltable granular phenol resin of the present invention is 0.65 or less. The variation coefficient of the particle size distribution is more preferably 0.6 or less. In the present specification, the “coefficient of variation in particle size distribution” is a value calculated by the following equation [1].

Coefficient of variation of particle size distribution = (d _84% −d _16% ) / (2 × average particle size) [1]
Here, in the above formula [1], d _84% and d _16% are particle diameters showing cumulative frequencies of 84% and 16% in the frequency distribution obtained by the laser diffraction / scattering method, respectively. Is the average particle size defined above. By setting the coefficient of variation of the particle size distribution to 0.65 or less, for example, it is possible to further improve the filling property when used as an organic filler and the space filling property when applied to a low-viscosity or functional carbon material. In addition, a granular phenol resin that can be applied over a wide range of industrial fields such as molding materials, paints, refractories, papermaking, friction materials, grindstones, and adhesives is provided. As a laser diffraction particle size measuring instrument, Microtrac X100 manufactured by Nikkiso Co., Ltd. can be suitably used.

  Furthermore, the particle shape of the non-heat-meltable granular phenol resin of the present invention is preferably as close to a true sphere as possible. Specifically, the sphericity is preferably 0.5 or more, more preferably 0.7 or more, and particularly preferably 0.9 or more. The closer the particle shape is to a perfect sphere, that is, the closer the sphericity is to 1.0, the greater is the filling property when used as an organic filler, and the lower the viscosity and the space filling property when applied to a functional carbon material. A granular phenol resin that can be improved and can be applied to a wide range of industrial fields such as molding materials, paints, refractories, papermaking, friction materials, grindstones, and adhesives is provided. In this specification, “sphericity” means a field of view containing about 300 primary particles in an optical microscope observation, and an aspect ratio (that is, a ratio of minor axis / major axis) is determined. It means the average value of these 10 aspect ratios when 10 lowest primary particles are selected and the aspect ratio in the projected cross section is measured for each of these 10 primary particles.

  Furthermore, it is preferable that the free phenol content of the non-heat-meltable granular phenol resin of the present invention is 500 ppm or less. The free phenol content is more preferably 300 ppm or less, still more preferably 200 ppm or less. By setting the free phenol content to 500 ppm or less, the safety when handling the phenol resin and the safety of the product when the phenol resin is applied to various products can be improved. Here, in this specification, “free phenol content” is defined as a value calculated by the following test. That is, about 10 g of a phenol resin sample is precisely weighed, extracted in 190 mL of methanol under reflux for 30 minutes, and filtered through a glass filter. The concentration of phenols in the filtrate is quantified by liquid chromatography, and the weight of phenols in the filtrate is calculated. The ratio between the phenol weight and the sample weight, that is, the phenol weight / phenol resin sample weight is defined as “free phenol content”.

  Although the method for manufacturing the non-heat-meltable granular phenol resin having the above excellent characteristics is not particularly limited, the following method can be preferably used. The manufacturing method of the non-heat-meltable granular phenol resin shown below is also included in the present invention.

<Method for producing non-heat-meltable granular phenolic resin>
The method for producing a non-heat-meltable granular phenol resin of the present invention includes the following steps (1) to (3). Hereinafter, each step will be described in detail.
(1) A granular phenol resin forming step of forming a granular phenol resin by reacting an aldehyde with a phenol in an aqueous medium in the presence of an acidic catalyst and a protective colloid agent,
(2) A heating step of heating the reaction solution containing the granular phenol resin to form a non-heat-meltable granular phenol resin,
(3) A separation / washing process in which the non-heat-meltable granular phenol resin is separated from the reaction solution and washed.

(1) Granular phenol resin formation process In this process, granular phenol resin is formed by making aldehydes and phenols react in an aqueous medium in presence of an acidic catalyst and a protective colloid agent. The aldehydes are not particularly limited, and examples thereof include formaldehyde, paraformaldehyde, glyoxal, and benzaldehyde. The aldehydes may be used alone or in combination of two or more. Especially, it is preferable that aldehydes are formaldehyde, paraformaldehyde, or these mixtures. As will be described later, one of the features of the method of the present invention is that a high concentration acidic catalyst is used. However, when paraformaldehyde, which is a polymer of formaldehyde, is used as the aldehyde, such a condition is used. Underneath, paraaldehyde is depolymerized, so it is believed that formaldehyde contributes substantially to the reaction. The type of aldehydes used and the amount used are preferably selected so as to dissolve in an aqueous medium during the reaction.

  Although it does not specifically limit as phenols, For example, phenol, naphthol, hydroquinone, resorcin, xylenol, pyrogallol etc. can be mentioned. One type of phenol may be used, or two or more types may be used in combination. Among these, considering the solubility in water and the balance between the performance and cost of the resulting phenol resin, the phenol is preferably phenol. The type of phenols to be used and the amount used are preferably selected so as to dissolve in an aqueous medium during the reaction.

  Specifically, for example, when phenol or the like is used as the phenol, the amount of phenol used (amount charged) is such that the concentration (weight ratio) of the phenol with respect to the total weight of the reaction solution is 10% by weight or less. Preferably it is selected. When phenols with lower water solubility (for example, naphthol) are used, they are guaranteed to dissolve in an aqueous medium during the reaction and have excellent characteristics (fine average particle size and high single particle) It is desirable to employ a lower concentration in order to express the rate). Here, the “total weight of the reaction solution” is the total weight of phenols, aldehydes, acidic catalyst, protective colloid agent and aqueous medium. By setting the concentration of phenols to 10% by weight or less based on the total weight of the reaction solution, temperature control from the reaction start stage to the granular phenol resin formation stage can be easily performed. For example, in the case of starting the reaction at around room temperature, if the concentration of phenols is 10% by weight or less, there is no excessive heat generation due to a runaway reaction or the like particularly in the initial stage of the reaction. A granular phenol resin having a small average particle size and suppressed secondary aggregation can be formed. In addition, although it is possible to make the density | concentration (weight ratio) of phenols with respect to the reaction liquid total weight higher than 10 weight%, in that case, it is often necessary to perform temperature management at the time of reaction appropriately.

  Moreover, it is preferable that the usage-amount (preparation amount) of the said aldehydes is selected so that the molar ratio of the phenols with respect to aldehydes may be 0.9 or less. The charging molar ratio of phenols to aldehydes is more preferably 0.75 or less, and further preferably 0.5 or less. By setting the molar ratio of phenols to aldehydes to 0.9 or less, the average particle size is small, secondary agglomeration is suppressed, and closer to a true sphere, the particle size distribution is narrow, and the free phenol content is reduced. A small amount of granular phenol resin can be formed. Moreover, secondary aggregation can be further suppressed by setting the charged molar ratio of phenols to aldehydes to 0.75 or less. In order to further improve the characteristics relating to these granular phenol resins, it is particularly preferable to set the molar ratio of phenols to aldehydes to 0.5 or less. There is no particular limitation on the lower limit of the molar charge ratio of phenols to aldehydes. For example, the molar charge ratio of phenols to aldehydes can be reduced by increasing the aldehydes within a range that dissolves in an aqueous medium. However, in consideration of the efficiency of the reaction, the molar ratio of the phenols to the aldehydes is preferably 0.1 or more.

  In this step, the aldehydes and phenols as described above are reacted in an aqueous medium. One of the characteristics of the production method of the present invention is that the reaction is performed using a high concentration acidic catalyst. . The acidic catalyst is preferably a strongly acidic catalyst. Examples of such include hydrochloric acid, phosphoric acid, sulfuric acid and the like. Among these, hydrochloric acid is more preferable in consideration of easy removal and side reactions when remaining. Note that non-volatile strong acids such as phosphoric acid and sulfuric acid can be sufficiently used depending on the use of the granular phenol resin. In addition, the high concentration specifically means that when the reaction is started near room temperature, the molar concentration of the acidic catalyst in the reaction solution is 2.0 mol / L or more, and more preferably 3 mol / L. L or more. In order to obtain a granular phenol resin having a small average particle size and reduced secondary agglomeration, and a granular phenol resin having a particle size distribution close to that of a spherical shape and a small free phenol content. When starting near normal temperature, it is necessary to make the molar concentration of the acidic catalyst in the reaction liquid 2.0 mol / L or more. Moreover, from the viewpoint of the reaction rate suitable for industrial production and the acid resistance of the incidental equipment, the molar concentration of the acidic catalyst is preferably 6 mol / L or less. Note that by increasing the reaction start temperature above room temperature, the molar concentration of the acidic catalyst necessary to achieve the same reaction rate is slightly lower than when the reaction start temperature is near room temperature.

  Another feature of the production method of the present invention is that the reaction between aldehydes and phenols is carried out in the presence of a protective colloid agent. Here, the protective colloid agent contributes to the formation of a granular phenol resin. In order to form a granular phenol resin having a small average particle size and reduced secondary agglomeration, and also a granular phenol resin that is closer to a true sphere, has a narrow particle size distribution, and has a low free phenol content. It is necessary to use such protective colloid agents. In the present invention, it is preferable to use a water-soluble protective colloid agent as the protective colloid agent. As the water-soluble protective colloid agent, for example, a water-soluble polysaccharide derivative can be preferably used. Specific examples of water-soluble polysaccharide derivatives that can be suitably used include alkali metal salts or ammonium salts of carboxymethyl cellulose; natural glues mainly composed of water-soluble polysaccharide derivatives such as gum arabic and acacia is there. When the alkali metal salt or ammonium salt of carboxymethyl cellulose is used, the degree of carboxymethylation of cellulose is not particularly limited, but those having a degree of carboxymethylation of about 75% are commercially available. Can be used. When the protective colloid agent is obtained as a dry powder, it may be directly added to and dissolved in the reaction solution, or an aqueous solution of the protective colloid agent may be prepared in advance and added to the reaction solution. Good.

  Although the usage-amount of the said protective colloid agent is not restrict | limited in particular, It is preferable that it is 0.01 to 1 weight% of the usage-amount of the said phenols by solid content weight. When the amount of the protective colloid agent used is less than 0.01% by weight, it is insufficient to make the average particle size of the phenol resin particles 20 μm or less. For example, other parameters such as the amount of phenols used and the stirring speed are used. Grain size control is required. In order to make the average particle size of the phenol resin particles 10 μm or less, the amount of the protective colloid agent used is preferably 0.04% by weight or more of the amount of phenols used. In addition, when the amount of the protective colloid agent used is more than 1% by weight of the amount of the phenols used, phenol resin particles having an average particle size of 10 μm or less can be obtained. Even if it is added, there is a tendency that an effect commensurate with it cannot be obtained. On the other hand, due to an increase in the viscosity of the reaction solution, the separation rate tends to decrease in the separation / washing step described later. Here, it should be noted that when the amount of the protective colloid agent used is within the above range, that is, 0.02 to 1% by weight of the amount of phenols used, the average particle size of the phenol resin particles is determined as the protective colloid agent. It can be controlled by adjusting the amount of use.

  Examples of the aqueous medium include water or a mixed solvent of water and a water-soluble organic solvent. In the present invention, an aqueous solvent is preferably used. The amount of the aqueous medium used is selected so that the concentration of the acidic catalyst is within the above range, and preferably the concentration of the phenol is further within the above preferable range.

  Next, a specific method for carrying out the reaction using the aldehydes, phenols, acidic catalyst and protective colloid agent will be described. Specific examples of the reaction include the following two methods. (I) a method in which an acidic catalyst, a protective colloid agent and aldehydes are mixed in an aqueous medium to prepare a mixed solution, and then a phenol is added while stirring the mixed solution; (ii) a protective colloid agent in the aqueous medium A method in which a mixed solution is prepared by mixing aldehydes and phenols, and then an acidic catalyst is added while stirring the mixed solution.

  Here, in any of the methods (i) and (ii), the mixed solution is preferably a substantially uniform solution. That is, it is preferable that the solute mixed in the aqueous medium is completely dissolved or at least almost completely dissolved. In the preparation of the mixed solution, the order of mixing is not particularly limited. The temperature at the start of the reaction of the mixed solution is not particularly limited, but is preferably about 10 to 50 ° C, more preferably about 20 to 40 ° C.

  In the method (i), the reaction between the aldehyde and the phenol is carried out by adding the phenol while stirring the mixed solution. The phenols may be added by adding the phenols directly to the mixed solution, or the phenols may be dissolved in water in advance and the aqueous solution added to the mixed solution. The reaction is preferably controlled so that the reaction temperature is about 10 to 60 ° C, preferably about 20 to 50 ° C. When the reaction temperature is less than about 10 ° C., the reaction rate tends to be low, and when the reaction temperature exceeds 60 ° C., there is a possibility that the particle size becomes coarse and secondary aggregates increase. The temperature at the start of the reaction of the mixed solution is about 20 to 30 ° C. and the concentration of phenols is 10% by weight or less with respect to the total weight of the reaction solution. The reaction can be carried out in the preferred temperature range with little management.

  In the method (ii), the reaction between the aldehyde and the phenol is performed by adding an acidic catalyst while stirring the mixed solution. The acidic catalyst may be added all at once, or may be added dropwise over a certain period of time. The addition of the acidic catalyst may be performed by directly adding the acidic catalyst to the mixed solution, or the acidic catalyst may be diluted with water and the diluted solution may be added to the mixed solution. The reaction temperature is preferably controlled to be about 10 to 60 ° C., preferably about 20 to 50 ° C., as in the case of (i) above.

  In any of the above methods (i) and (ii), as the reaction proceeds, the reaction solution gradually becomes clouded (suspended) and a granular phenol resin is formed. Typically, this occurs several tens of seconds to several minutes after the addition of phenols or acidic catalyst. The time required for whitening, that is, precipitation of phenol resin particles, tends to be shorter in the method (ii) than in the method (i). Further, after the white turbidity, the reaction solution typically exhibits a light pink color to a deep pink color. In the present invention, it is preferable to continue the reaction until such coloring is observed. The time until coloring after clouding is generally several tens of minutes to several hours. In the method described in Patent Document 1 above, it was necessary to stop stirring after precipitation of the phenol resin particles in order to avoid aggregation of particles and forming a bowl-like shape. According to the manufacturing method of the invention, stirring can be continued as it is even after precipitation of the phenol resin particles. Therefore, according to the production method of the present invention, the temperature of the reaction solution can be more strictly controlled, and as a result, the phenol resin can be subjected to the next heating step in a uniform polymerization degree and crosslinking degree. Become. This can contribute to the homogeneity of the finally obtained granular phenolic resin.

(2) Heating step In this step, the granular phenol resin is made non-heat-meltable by heating the reaction solution containing the granular phenol resin. Such non-heat melting property is brought about by crosslinking and curing of the resin by heating. The heating temperature of the reaction liquid in this step is preferably 60 ° C. or higher, more preferably 70 ° C. or higher. Moreover, the heating temperature of the reaction solution is preferably 100 ° C. or lower, more preferably 90 ° C. or lower. When the heating temperature is less than 60 ° C., there is a possibility that sufficient non-thermal meltability cannot be obtained. In addition, sufficient non-thermal meltability here means having "non-heat meltability" defined above. Moreover, when heating temperature exceeds 100 degreeC, there exists a possibility that the reactor which has a capacitor | condenser may be required, or acid resistance, such as incidental equipment, may become a problem. Even when the heating temperature is as relatively low as about 60 ° C., it is possible to impart sufficient non-thermal meltability by providing a sufficient holding time. By adjusting the heating temperature and the heating time within the above preferred ranges, the degree of polymerization and the degree of crosslinking can be adjusted according to the intended use.

  The heating time is not particularly limited as long as sufficient non-thermal meltability can be imparted to the granular phenol resin, and is typically about several minutes to several hours although it depends on the heating temperature. In addition, after completion of the heat treatment, when proceeding to the next step, the reaction solution may be cooled to an appropriate temperature of room temperature to about 50 ° C., or may proceed directly to the next step without cooling the reaction solution. .

(3) Separation / Washing Step In this step, the obtained non-heat-meltable granular phenol resin is separated from the reaction solution and washed. As the separation method, for example, filtration or pressing can be suitably used. As a device for such a separation operation, for example, a filtration device, a centrifugal dehydrator, a belt press, a filter press, or the like can be used. Separation methods using evaporation such as distillation under reduced pressure or spray drying are not preferable because the reaction solution contains a high concentration acidic catalyst and may damage the equipment. When performing the separation operation by filtration, various filter aids such as diatomaceous earth and flocculants may be used. Note that the granular phenol resin of the present invention has a specific gravity of about 1.2 to 1.3 and settles upon standing, so that a preliminary operation such as decantation may be performed prior to the separation operation.

  Next, the separated granular phenol resin is washed. This washing operation completes the reaction almost completely. As a specific method of washing, for example, (i) a method of adding a washing solution to the phenol resin cake separated by the above separation operation (for example, pouring the washing solution into the phenol resin cake on the separated filter and pressurizing the washing solution) Or (ii) a method in which the phenol resin cake separated in the washing liquid is dispersed and then separated again. Water can be suitably used as the cleaning liquid. The acidic component in the phenol resin cake can be removed by washing with water.

  Moreover, you may perform neutralization reaction by making it contact with the aqueous solution which exhibits basicity as part of washing | cleaning operation or instead of the washing | cleaning operation by the said water. By performing the neutralization reaction, the acidic catalyst component contained in the phenol resin cake can be effectively removed. As the basic aqueous solution used for the neutralization reaction, an organic or inorganic weakly basic aqueous solution is preferably used. If a strongly basic concentrated aqueous solution is used, the phenol resin particles may be discolored or dissolved. As the weakly basic aqueous solution, for example, a dilute aqueous solution of ammonia can be suitably used. This is because when a dilute aqueous solution of ammonia is used, the salt produced is water-soluble, so that the salt can be removed by washing with water, and ammonia itself can be sublimated and removed by heating.

  The washed granular phenol resin can be used in a water-containing state without being dried, and the non-heat-meltable granular phenol resin containing such water is also within the scope of the present invention. For example, such a hydrous phenolic resin can be used when preparing an aqueous dispersion. Or you may provide a drying process after a washing | cleaning process. Although it does not specifically limit as a drying method, For example, the method using a shelf-type stationary dryer, an airflow dryer, a fluidized bed dryer etc. can be mentioned. By performing drying, a non-heat-meltable granular phenol resin exhibiting good fluidity with a water content of about 5% or less can be obtained. According to the method of the present invention, it is possible to obtain a granular phenol resin having a high single particle ratio by performing mild crushing as necessary, but using a crusher or the like during or after the drying step. Furthermore, the single particle ratio may be improved.

  According to the method for producing a non-heat-meltable granular phenol resin of the present invention as described above, the non-heat-meltable granule having an average particle diameter of 20 μm or less, particularly 10 μm or less, and a single particle ratio of 0.7 or more. The phenol resin can be produced by a relatively simple method and a method suitable for mass production. Furthermore, it is possible to produce a non-heat-meltable granular phenol resin that has these characteristics, has a narrow particle size distribution, has a spherical shape, and has a very low free phenol content.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Example 1>
After preparing 2000 g of a mixed solution having a formaldehyde concentration of 10 wt% and a hydrochloric acid concentration of 16 wt% using 35 wt% hydrochloric acid and a 36 wt% aqueous formaldehyde solution, 8 g of a 2 wt% aqueous solution of carboxymethylcellulose sodium salt was added to the mixed solution. And stirred to make a homogeneous solution. Next, after adjusting the temperature of the homogeneous solution to 20 ° C., 70 g of 95 wt% phenol at 30 ° C. was added with stirring. The concentration of phenols relative to the total weight of the reaction solution is 3.2% by weight, the molar ratio of phenol to formaldehyde is 0.11, and the molar concentration of hydrochloric acid in the reaction solution is 4.7 mol / L. About 120 seconds after the addition of phenol, the reaction solution became cloudy. After the white turbidity, the reaction was continued at a reduced stirring speed. As a result, the reaction solution colored light pink about 30 minutes after the addition of phenol. At this time, the temperature of the reaction solution had reached 30 ° C. After coloring the reaction solution, the reaction solution was heated to 80 ° C. by external heating and kept at this temperature for 30 minutes. Next, this reaction solution was filtered, and the resulting cake was washed with 500 g of water, then suspended in 500 g of 0.5 wt% aqueous ammonia solution, and neutralized at 40 ° C. for 1 hour. After the neutralization reaction, the suspension was subjected to suction filtration using an aspirator, washed with 500 g of water, and dried with a dryer at 50 ° C. for 10 hours to obtain 80 g of a pale yellow granular phenol resin.

<Example 2>
A granular phenol resin was obtained by carrying out the reaction in the same manner as in Example 1 except that the formaldehyde concentration in the mixed solution was 18 wt% and the hydrochloric acid concentration was 18 wt%. The concentration of phenols relative to the total weight of the reaction solution is 3.2% by weight, the molar ratio of phenol to formaldehyde is 0.06, and the molar concentration of hydrochloric acid in the reaction solution is 5.3 mol / L. The reaction solution was clouded about 150 seconds after the addition of phenol, and there were no operational problems such as adhesion of the resin to the vessel wall. In FIG. 2, the optical microscope photograph of the granular phenol resin obtained by the present Example is shown.

<Example 3>
A granular phenol resin was obtained by carrying out the reaction in the same manner as in Example 1 except that the formaldehyde concentration in the mixed solution was 7 wt% and the hydrochloric acid concentration was 20 wt%. The concentration of phenols with respect to the total weight of the reaction solution is 3.2% by weight, the molar ratio of phenol to formaldehyde is 0.15, and the molar concentration of hydrochloric acid in the reaction solution is 5.9 mol / L. The reaction solution was clouded about 30 seconds after the addition of phenol, and there were no operational problems such as adhesion of the resin to the vessel wall. In FIG. 3, the optical microscope photograph of the granular phenol resin obtained by the present Example is shown.

<Example 4>
A reaction was carried out in the same manner as in Example 1 except that 52 g of 95% by weight phenol was added to obtain 62 g of a granular phenol resin. The concentration of phenols relative to the total weight of the reaction solution is 2.4% by weight, the molar ratio of phenol to formaldehyde is 0.08, and the molar concentration of hydrochloric acid in the reaction solution is 6.0 mol / L.

<Example 5>
The reaction was conducted in the same manner as in Example 1 except that 105 g of 95% by weight phenol was added to obtain 115 g of a granular phenol resin. The concentration of phenols with respect to the total weight of the reaction solution is 4.7% by weight, the molar ratio of phenol to formaldehyde is 0.16, and the molar concentration of hydrochloric acid in the reaction solution is 5.8 mol / L.

<Example 6>
A mixed solution 1156 g was prepared by mixing 556 g of a 36 wt% aqueous formaldehyde solution, 70 g of 95 wt% phenol, and 530 g of water. Then, 8 g of a 2 wt% aqueous solution of carboxymethyl cellulose sodium salt was added to the mixed solution and stirred. A homogeneous solution. Next, after adjusting the temperature of the homogeneous solution to 20 ° C., 914 g of 35 wt% hydrochloric acid at 30 ° C. was added with stirring. The concentration of phenols with respect to the total weight of the reaction solution was 3.2% by weight, the molar ratio of phenol to formaldehyde was 0.11, and the molar concentration of hydrochloric acid in the reaction solution was 4.7 mol / L. Is the same. About 20 seconds after the addition of hydrochloric acid, the reaction solution became cloudy. When the reaction was continued even after white turbidity, the reaction solution colored pink about 30 minutes after the addition of hydrochloric acid. Thereafter, heating, separation, washing and drying were performed in the same manner as in Example 1 to obtain 78 g of a granular phenol resin.

<Example 7>
The reaction was conducted in the same manner as in Example 6 except that 204 g of 95% by weight phenol was used, and 240 g of granular phenol resin was obtained. The concentration of phenols with respect to the total weight of the reaction solution is 8.8% by weight, the molar ratio of phenol to formaldehyde is 0.31, and the molar concentration of hydrochloric acid in the reaction solution is 4.4 mol / L.

<Example 8>
A reaction was carried out in the same manner as in Example 6 except that 278 g of a 36 wt% formaldehyde aqueous solution, 204 g of 95 wt% phenol, and 803 g of water were used to prepare a mixed solution, thereby obtaining 200 g of a granular phenol resin. The concentration of phenols relative to the total weight of the reaction solution is 8.8% by weight, the molar ratio of phenol to formaldehyde is 0.62, and the molar concentration of hydrochloric acid in the reaction solution is 4.4 mol / L.

<Example 9>
The reaction was carried out in the same manner as in Example 1 except that a paraformaldehyde aqueous solution having the same weight concentration was used instead of the 36% by weight aqueous formaldehyde solution. The progress of the reaction was almost the same as in Example 1, and 77 g of granular phenol resin was obtained.

<Example 10>
The procedure was carried out except that the hydrochloric acid concentration in the mixed solution was 8% by weight, and after adding 95% by weight of phenol, the reaction solution was heated to 50 ° C. by external heating and heated to 80 ° C. after coloring the reaction solution. Reaction was carried out in the same manner as in Example 1 to obtain a granular phenol resin. The concentration of phenols relative to the total weight of the reaction solution is 3.2% by weight, the molar ratio of phenol to formaldehyde is 0.11, and the molar concentration of hydrochloric acid in the reaction solution is 2.3 mol / L.

<Comparative Example 1>
A reaction was carried out in the same manner as in Example 1 except that 8 g of water was used instead of 8 g of the 2% by weight aqueous solution of carboxymethylcellulose sodium salt to obtain 80 g of a granular phenol resin. The course of the reaction was the same as in Example 1 except that the reaction solution became cloudy about 95 seconds after the addition of phenol. In FIG. 4, the optical microscope photograph of the granular phenol resin obtained by this comparative example is shown.

<Comparative example 2>
The reaction was performed in the same manner as in Example 1 except that the hydrochloric acid concentration in 2000 g of the mixed solution was changed to 5% by weight. No white turbidity was observed in the reaction solution, and no granular phenol resin was obtained. The molar concentration of hydrochloric acid in the reaction solution is 1.45 mol / L.

<Comparative Example 3>
The reaction was performed in the same manner as in Example 6 except that 140 g of 36 wt% aqueous formaldehyde solution, 204 g of 95 wt% phenol and 940 g of water were used for preparing the mixed solution. The concentration of phenols with respect to the total weight of the reaction solution is 8.8% by weight, the molar ratio of phenol to formaldehyde is 1.23, and the molar concentration of hydrochloric acid in the reaction solution is 4.4 mol / L. When the heating of the reaction solution was started, the resin adhered to the reaction vessel wall. The powder which was in a suspended state at the completion of heating was filtered off, washed, neutralized and dried to obtain about 50 g of a granular phenol resin. When the particles were observed with a microscope, many irregular particles were present, and the sphericity and the single particle ratio could not be obtained.

About the granular phenol resin of the said Examples 1-10 and Comparative Examples 1-3, the characteristic hung up below was measured. The measurement method and measurement conditions are as follows. The measurement results are shown in Table 1 together with the reaction conditions.
(1) Non-thermal meltability: About 5 g of granular phenol resin sample was inserted between two 0.2 mm thick stainless steel plates and pressed for 2 minutes with a total load of 50 kg with a press machine preheated to 100 ° C. Sometimes, when melting and / or fusing, the granular phenolic resin forms a flat plate, the phenolic resin particles are deformed, or the phenolic resin particles do not adhere to each other, it is determined as having “non-thermomeltability” did.
(2) Boiling methanol solubility: About 10 g of phenol resin sample was precisely weighed and heated under reflux in about 500 mL of substantially anhydrous methanol for 30 minutes. Filter through 3 glass filter and wash the residue on the glass filter with about 100 mL of anhydrous methanol. Next, the residue on the glass filter after washing is dried at 40 ° C. for 5 hours, and then the residue is precisely weighed. From the obtained residue weight after drying and phenol resin sample weight, boiling methanol solubility is calculated based on the following formula.

Boiling methanol solubility (% by weight) = (Difference between phenol resin sample weight and residue weight after drying) / (phenol resin sample weight) × 100
(3) Average particle diameter: It is a 50% cumulative frequency value of the frequency distribution measured by a laser diffraction particle size analyzer (Microtrac X100 manufactured by Nikkiso Co., Ltd.).
(4) Single particle ratio: The granular phenol resin is dispersed in water droplets and observed with an optical microscope. In a randomly selected field of view containing about 300 primary particles, the total number of primary particles and single particles The ratio when the number of particles is counted, that is, the number of single particles / the total number of primary particles.
(5) Coefficient of variation of particle size distribution: An aqueous dispersion was prepared using a granular phenol resin, and the following formula [1] was obtained from the frequency distribution measured by a laser diffraction particle size measuring instrument (Microtrac X100 manufactured by Nikkiso Co., Ltd.). Calculated by

Coefficient of variation of particle size distribution = (d _84% −d _16% ) / (2 × average particle size) [1]
Here, in the above formula [1], d _84% and d _16% are particle diameters indicating the cumulative frequencies of 84% and 16%, respectively, in the obtained frequency distribution. When the coefficient of variation was 0.65 or less, it was determined to have a narrow particle size distribution.
(6) Sphericity: A field of view containing about 300 primary particles is randomly determined in observation with an optical microscope, and 10 primary particles having the lowest aspect ratio (ie, ratio of minor axis / major axis). It is the average value of these 10 aspect ratios when the aspect ratio in the projected cross section is measured for each of these 10 primary particles.
(7) Free phenol content: Defined as a value calculated by the following test. That is, about 10 g of a phenol resin sample is precisely weighed, extracted in 190 mL of methanol under reflux for 30 minutes, and filtered through a glass filter. The concentration of phenols in the filtrate is quantified by liquid chromatography, and the weight of phenols in the filtrate is calculated. The ratio between the phenol weight and the sample weight, that is, the phenol weight / phenol resin sample weight is defined as “free phenol content”.

<Example 11>
Except for changing the amount of carboxymethylcellulose sodium salt, which is a protective colloid agent, with respect to phenol, the reaction was carried out in the same manner as in Example 1 to obtain a granular phenol resin, and then the average particle size of each granular phenol resin was determined. It was measured. FIG. 5 is a graph showing the relationship between the concentration of the protective colloid agent (weight (ppm) of the protective colloid agent relative to the total weight of the reaction solution) and the average particle diameter of the granular phenol resin. The measurement range of the protective colloid agent concentration of 13 to about 103 ppm corresponds to a range of 0.04 to 0.32% by weight when converted to a protective colloid agent use amount / phenol use amount ratio (% by weight). As shown in FIG. 5, it was found that the average particle diameter of the granular phenol resin obtained can be controlled by adjusting the amount of the protective colloid agent used. That is, it was found that the average particle size can be reduced by increasing the amount of the protective colloid agent used.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

The SEM photograph of a preferable example of the non-heat-meltable granular phenol resin of this invention is shown. The optical microscope photograph of the granular phenol resin obtained in Example 2 is shown. The optical microscope photograph of the granular phenol resin obtained in Example 3 is shown. The optical micrograph of the granular phenol resin obtained by the comparative example 1 is shown. It is a graph which shows the relationship between the density | concentration of a protective colloid agent (weight (ppm) of a protective colloid agent with respect to the reaction liquid total weight), and the average particle diameter of granular phenol resin.

Claims (15)

  A non-heat-meltable granular phenol resin having an average particle size of 20 μm or less and a single particle ratio of 0.7 or more.   2. The non-heat-meltable granular phenol resin according to claim 1, wherein the average particle size is 10 μm or less. The non-heat-meltable granular phenol resin according to claim 1 or 2, wherein the coefficient of variation of the particle size distribution represented by the following formula [1] is 0.65 or less.
Coefficient of variation of particle size distribution = (d _84% −d _16% ) / (2 × average particle size) [1]
Here, d _84% and d _16% are particle diameters showing cumulative frequencies of 84% and 16%, respectively, in the frequency distribution obtained by the laser diffraction / scattering method.   The non-heat-meltable granular phenol resin according to any one of claims 1 to 3, wherein the sphericity is 0.5 or more.   The non-heat-meltable granular phenol resin according to any one of claims 1 to 4, wherein a free phenol content is 500 ppm or less. (1) A granular phenol resin forming step of forming a granular phenol resin by reacting an aldehyde with a phenol in an aqueous medium in the presence of an acidic catalyst and a protective colloid agent;
(2) A heating step of heating the reaction solution containing the granular phenol resin to form a non-heat-meltable granular phenol resin,
(3) separating and washing the non-heat-meltable granular phenol resin from the reaction liquid, and a separation / washing process,
The method for producing a non-heat-meltable granular phenol resin, wherein the acidic catalyst has a molar concentration of 2.0 mol / L or more in the reaction solution.   The method for producing a non-heat-meltable granular phenol resin according to claim 6, wherein the acidic catalyst is hydrochloric acid and the aldehyde is formaldehyde, paraformaldehyde or a mixture thereof.   The method for producing a non-heat-meltable granular phenol resin according to claim 6 or 7, wherein a molar ratio of the phenols to the aldehydes is 0.9 or less.   The method for producing a non-heat-meltable granular phenol resin according to any one of claims 6 to 8, wherein the protective colloid agent is a water-soluble polysaccharide derivative.   The non-heat-meltable granular phenol resin obtained using the method in any one of Claims 6-9.   The non-heat-meltable granular phenol resin according to claim 10, wherein the average particle size is 20 µm or less and the single particle ratio is 0.7 or more.   The non-heat-meltable granular phenol resin according to claim 11, wherein the average particle size is 10 μm or less.   The non-heat-meltable granular phenol resin according to claim 11 or 12, wherein the coefficient of variation of the particle size distribution represented by the formula [1] is 0.65 or less.   The non-heat-meltable granular phenol resin according to any one of claims 11 to 13, wherein the sphericity is 0.5 or more.   The non-heat-meltable granular phenol resin according to any one of claims 11 to 14, wherein a free phenol content is 500 ppm or less.