JP6534056B2 - Method for producing spherical furan resin - Google Patents

Description

  The present invention relates to a method for producing a spherical furan resin.

  Self-condensation reaction of furfuryl alcohol, or condensation reaction of furfuryl alcohol with aldehydes, condensation reaction of furfuryl alcohol with phenols, or furfuryl alcohol with phenols and aldehydes A furan resin can be prepared by condensation reaction. The furan resin has excellent properties such as high performance in both acid resistance and alkali resistance.

  Thus, when condensation reaction of furfuryl alcohol etc. is carried out, the condensation reaction product is dispersed in the reaction solution by the action of the dispersing agent by adding and dispersing the dispersing agent in the reaction solution, and the furan resin is formed into a spherical form. Can be prepared. The above condensation reaction is generally carried out using an acid as a reaction catalyst, and as this acid catalyst, for example, phosphoric acid, xylene sulfonic acid, p-toluene sulfonic acid and the like are used (for example, Patent Document 1) See, for example, Patent Document 2).

Unexamined-Japanese-Patent No. 2007-63377 Japanese Patent Application Publication No. 2007-66669

  The condensation reaction for preparing the furan resin as described above takes place on the acid side, and is usually carried out by adjusting the pH to about 1.5 to 2.5. However, in preparing furan resin in this way, it is very difficult to prepare furan resin as a solid resin. That is, although the condensation reaction of furfuryl alcohol or the like proceeds in water using water as a reaction solvent, polymerization does not easily progress until it becomes insoluble in water.

  The reason is not clear, but furfuryl alcohol and aldehydes and phenols to be reacted with furfuryl alcohol are water-soluble, and the above-mentioned phosphoric acid and xylene sulfonic acid conventionally used as a reaction catalyst in condensation reactions And para-toluenesulfonic acid are also water-soluble, and the present inventors speculate that this may be the cause.

  That is, since the condensation reaction of furfuryl alcohol or the like proceeds in water using water as a reaction solvent, if the condensation reaction proceeds to be polymerized, a resin insoluble in water can be formed. However, at this time, although the above-mentioned reaction catalyst that is water soluble is slightly present in the formed condensation reaction product, most of it is transferred into the water of the reaction solution. Therefore, the polymerization of the produced reaction condensate does not proceed, and even if the reaction is continued for a long time, the polymerization is insufficient and the reaction product can not be solidified. The furan resin can not be removed as a solid from the reaction solution.

  The present invention has been made in view of the above-mentioned point, and it is an object of the present invention to be able to produce a spherical solid furan resin by condensation reaction so as to be in an insoluble and infusible state.

  The method for producing a spherical furan resin according to the present invention is characterized in that a condensation reaction is performed using furfuryl alcohol in the presence of a dispersing agent with a naphthalenesulfonic acid as a catalyst to form a spherical solid furan resin. In particular, the condensation reaction of furfuryl alcohol alone with naphthalene sulfonic acids as a catalyst, or the condensation reaction of furfuryl alcohol with aldehydes with naphthalene sulfonic acids as a catalyst, or furfuryl alcohol with phenols as naphthalene sulfone It is characterized in that spherical furan resin is formed by condensation reaction using acids as a catalyst, or condensation reaction of furfuryl alcohol, phenols and aldehydes using naphthalene sulfonic acids as a catalyst. It is intended to.

  Naphthalene sulfonic acids are hardly soluble or insoluble in water, and the above condensation reaction can be promoted by reacting naphthalene sulfonic acids as a reaction catalyst, and spherical furan resin can be formed in a solid state. is there.

  And, the present invention is characterized in that the condensation reaction is carried out until the spherical solid furan resin to be produced becomes insoluble and infusible.

  The spherical furan resin obtained by the condensation reaction until it becomes insoluble and infusible as described above can be used as an organic filler or the like.

  According to the present invention, the condensation reaction of furfuryl alcohol alone in the presence of the dispersant, or the condensation reaction of furfuryl alcohol with aldehydes, or the condensation reaction of furfuryl alcohol with phenols, or When condensation reaction of furyl alcohol, phenols and aldehydes is carried out, the condensation reaction product can be advanced to cause the condensation reaction product to be polymerized by reacting naphthalene sulfonic acids as a reaction catalyst, and it is spherical in the solid state It is possible to produce furan resin.

  And in the present invention, the condensation reaction can be carried out until the spherical solid furan resin to be produced becomes insoluble and infusible, and in this case, it can be used as a filler or the like.

  Hereinafter, embodiments of the present invention will be described.

  The spherical furan resin can be produced by condensation reaction of furfuryl alcohol as a main raw material, in the presence of a dispersant and a reaction catalyst. When furfuryl alcohol is used alone, furan resin can be prepared by self-condensation reaction of furfuryl alcohol as in [Chemical Formula 1].

  A furan resin can be prepared by condensation reaction of furfuryl alcohol and aldehydes as shown in [Formula 2], using furfuryl alcohol and aldehydes as raw materials.

  As the above-mentioned aldehydes, formalin which is a form of aqueous solution of formaldehyde is most suitable, but paraformaldehyde, acetaldehyde, benzaldehyde, furfural and the like can also be used. Further, trioxane, tetraoxane or the like which is decomposed to form aldehyde can also be used. Aldehydes can be used alone or in combination of two or more of them.

  Although the compounding ratio of furfuryl alcohol and aldehydes is not specifically limited, The range of 0.1-0.5 mol of aldehydes is preferable with respect to 1 mol of furfuryl alcohols.

  A furan resin can be prepared by using furfuryl alcohol and phenol as raw materials and subjecting furfuryl alcohol and phenol to a condensation reaction as shown in [Chemical formula 3].

  As the above-mentioned phenols, phenol and derivatives of phenol can be used. Examples of phenol derivatives include trifunctional ones such as m-cresol, resorcinol and 3,5-xylenol, tetrafunctional ones such as bisphenol A, bisphenol S and dihydroxydiphenylmethane, o-cresol, p-cresol and p Di-functional o- or p-substituted phenols such as ter-butylphenol, p-phenylphenol, p-cumylphenol, p-nonylphenol, 2,4 or 2,6-xylenol, Furthermore, halogenated phenols substituted with chlorine or bromine can also be used. As phenols, in addition to selecting and using one of them, plural kinds of phenols can be used in combination.

  Although the compounding ratio of furfuryl alcohol and phenols is not specifically limited, The range of 0.05-0.7 mol of phenols with respect to 1 mol of furfuryl alcohols is preferable.

  A furan resin can be prepared by condensation reaction of furfuryl alcohol, phenols and aldehydes as shown in Chemical formula 4 using furfuryl alcohol, phenols and aldehydes as raw materials. As the phenols and aldehydes, those described above can be used.

  Although the compounding ratio of furfuryl alcohol, phenols, and aldehydes is not specifically limited, 0.05 to 0.7 mol of phenols and 0.05 to 0.9 aldehydes are used with respect to 1 mol of furfuryl alcohol. A molar range is preferred.

  As a catalyst for the above condensation reaction, the present invention uses naphthalene sulfonic acids. In the present invention, naphthalenesulfonic acids mean naphthalenesulfonic acid and its derivatives. In addition to naphthalene monosulfonic acid (one-naphthalene sulfonic acid and 2-naphthalene sulfonic acid) in which one sulfone group is substituted to a naphthyl group in naphthalene sulfonic acid, naphthalene disulfonic acid, naphthalene trisulfonic acid, naphthalene tetra sulfone Included are those in which a plurality of sulfone groups are added to a naphthyl group such as an acid.

  As a derivative of naphthalene sulfonic acid, alkyl naphthalene sulfonic acid can be mentioned as a typical thing, For example, isopropyl naphthalene sulfonic acid of Formula (2), diisopropyl naphthalene sulfonic acid of Formula (3), butyl of Formula (4) Naphthalene sulfonic acid, dibutyl naphthalene sulfonic acid of formula (5), isobutyl naphthalene sulfonic acid of formula (6), diisobutyl naphthalene sulfonic acid of formula (7), 3-nonyl-1,5-naphthalene disulfonic acid of formula (8) 3,7-dihexyl-1,5-naphthalenedisulfonic acid of the formula (9), 4-octyl-2,6-naphthalenedisulfonic acid (4-nonyl-2,6-naphthalenedisulfonic acid) of the formula (10), Examples of 4,8-di (2-methyloctyl) -1,5-naphthalenedisulfonic acid of the formula (11) It can gel.

  In addition to those listed above as the alkyl naphthalene sulfonic acid, 3-hexyl-1,5-naphthalene disulfonic acid, 3-octyl-1,5-naphthalene disulfonic acid, 3-dioctyl-1,5-naphthalene disulfonic acid, 4 , 8-dioctyl-2,6-naphthalenedisulfonic acid, 3,7-dinonyl-1,5-naphthalenedisulfonic acid, 4,8-dinonyl-2,6-naphthalenedisulfonic acid, 4- (2-methyloctyl)- 2,6-Naphthalenedisulfonic acid, 3,7-di (2-methyloctyl) -1,5-naphthalenedisulfonic acid, 3-decyl-1,5-naphthalenedisulfonic acid, 3,7-didecyl-1,5- Naphthalene disulfonic acid, 3,7-di (2-methylnonyl) -1,5-naphthalene disulfonic acid, 3,7-didodecyl-1,5-na Or the like can also be mentioned the data range sulfonic acid. The alkyl group in the alkyl naphthalene sulfonic acid generally has 6 to 14 carbon atoms.

  As derivatives of naphthalene sulfonic acid, ones other than the above alkyl naphthalene sulfonic acids can also be used, and examples thereof include 7-amino-4-hydroxy-2-naphthalene sulfonic acid of the formula (12) and 13) 2-hydroxy-3,6-naphthalenedisulfonic acid etc. can be mentioned. As the naphthalenesulfonic acids, one type is selected from the above and used, and a plurality of types can also be used in combination. Although the compounding quantity of the naphthalenesulfonic acids which are reaction catalysts changes with the kinds greatly, and is not specifically limited, The range of 0.05-10 mass% is preferable with respect to furfuryl alcohol.

  The above-mentioned dispersant also acts as a kind of emulsifier, and examples thereof include gum arabic, polyvinyl alcohol, glue, guar gum, goth gum, carboxymethyl cellulose, hydroxyethyl cellulose, solubilized starch, agar, sodium alginate and the like. it can. Among these, although it can be used individually by 1 type or in combination of multiple types, among these, gum arabic and polyvinyl alcohol can be used preferably. The addition amount of the dispersing agent greatly varies depending on the emulsifying effect of the dispersing agent, and is not particularly limited, but a range of 0.1 to 10.0% by mass with respect to furfuryl alcohol is preferable, particularly 0.5 The range of -7.0 mass% is preferable.

  Then, the above furfuryl alcohol, and, if necessary, an aldehyde, a phenol, a dispersant, and a naphthalenesulfonic acid as a reaction catalyst are taken in a reaction vessel and subjected to a condensation reaction. At this time, water is used as a reaction medium, and the condensation reaction is carried out in water, and furfuryl alcohol, and as necessary, aldehydes and phenols, and further dispersing agent and naphthalene sulfonic acid are dissolved or dispersed in water. In the state, the condensation reaction is allowed to proceed while stirring the reaction system. The amount of water is not particularly limited as long as it can uniformly stir the reaction system, but it is preferable to set the solid content to be in the range of about 10 to 70% by mass. . Stirring is sufficient as long as the reaction solution can be mixed by causing a forced flow in the reaction solution, for example, using a two-blade, three-blade, screw, etc., rotating in one or both directions. Can be stirred.

  In the early stage of the reaction, the reaction solution is nearly transparent, but the self condensation reaction of furfuryl alcohol, or the condensation reaction of furfuryl alcohol with aldehydes, or the condensation reaction of furfuryl alcohol with phenols, furfuryl alcohol with phenols A condensation product of the condensation reaction of aldehydes precipitates in the solution of the reaction system, and the solution becomes milky with progress of the reaction. Then, the condensate is dispersed in the reaction solution by the action of the dispersing agent to form spherical particles in the reaction solution.

  Here, naphthalenesulfonic acids used as a reaction catalyst are poorly soluble or insoluble in water, and even if the condensate produced by the condensation reaction becomes insoluble in water and is precipitated from the water of the reaction solution, The sulfonic acids move little to the water of the reaction solution, and most stay in the condensate. Therefore, the condensation reaction of the condensate can be further advanced by the catalytic action of naphthalenesulfonic acids, and the condensate can be polymerized. As a result, the above-mentioned condensate is polymerized by the catalytic action of naphthalenesulfonic acids until it becomes solid in the state of being precipitated as spherical particles from the reaction solution, and spherical furan resin is formed in the solid state. It is possible to Since the naphthalenesulfonic acids are poorly soluble or insoluble in water, the above condensation reaction can be allowed to proceed without being greatly affected by the pH of the reaction system, but the pH of the reaction system is 1.5 to 3 It is preferable to be in the range of about 0.

  After proceeding the condensation reaction to the desired extent as described above, the solution of the reaction system is cooled and stirring is stopped, and spherical particles of solid furan resin separate from the reaction solution. Since the spherical particles are water-containing particulates, the solution of the reaction system is separated by decantation and then removed from the reaction solution by filtration or the like, washed with water if necessary, and dried to obtain spherical furan resin. Can be obtained. Here, in the present invention, a solid furan resin means that the furan resin itself exhibits a solid state at normal temperature (30 ° C.).

  In the condensation reaction of fluryl alcohol etc. in the presence of the dispersing agent as described above, the dispersing agent is added to the reaction solution from the beginning of the condensation reaction of the furfuryl alcohol etc., and in the presence of the dispersing agent from the beginning to the end The condensation reaction of furfuryl alcohol etc. may be carried out in the first place, or the condensation reaction of furfuryl alcohol etc. is started at first without adding a dispersant, and then it is dispersed in the reaction solution from the middle of the condensation reaction. An agent may be added to continue the condensation reaction in the presence of the dispersing agent in the middle.

  When the condensation reaction of furfuryl alcohol or the like is performed from the beginning in the presence of the dispersant, the furan resin condensate formed by the condensation reaction of the furfuryl alcohol or the like is dispersed by the dispersant from the beginning of the reaction and small particles are produced The spherical furan resin produced is obtained as a relatively small particle size.

  On the other hand, after initiating the condensation reaction of furfuryl alcohol etc., if the dispersing agent is added in the middle to continue the condensation reaction in the presence of the dispersing agent, the furan formed by the condensation reaction of furfuryl alcohol etc. The resin condensate is produced as relatively large particles because it is not dispersed at the beginning of the reaction, and the furan resin produced is obtained as one having a relatively large particle size.

  By thus adjusting the addition time of the dispersant, it is possible to adjust the particle diameter of the obtained spherical furan resin, but when the addition time of the dispersant is too late, the surface smoothness of the spherical furan resin is impaired. If a dispersant is added in the middle of the condensation reaction, there is a risk that it will agglomerate or form particles without becoming particles, so 1/10 to 1/1 of the total reaction time after the condensation reaction is started. It is desirable to set within the time range in which 2 hours have passed.

  And, as described above, in forming spherical furan resin in a solid state by condensation reaction of furfuryl alcohol etc. in the presence of dispersant and naphthalene sulfonic acids, this spherical furan resin has a thermosetting property The uncured spherical furan resin can be obtained by stopping the condensation reaction with The state of having a thermosetting property means that the spherical furan resin is heated, and once melted, has a property of causing crosslinking reaction and curing.

  Since naphthalenesulfonic acids are poorly soluble or insoluble in water, condensation reactions can be made to proceed mildly by suppressing runaway, and the furan resin produced becomes insoluble and infusible. It is easy to stop the condensation reaction before Thus, in order to stop a condensation reaction in the state which solid furan resin has a thermosetting property, it can carry out by cooling a reaction system and reducing the temperature of a reaction solution or solid furan resin to 50 degrees C or less, for example .

  The timing at which the condensation reaction is stopped in a state in which the spherical furan resin has a thermosetting property can be easily known by sampling the spherical furan resin from the reaction solution every predetermined time to confirm the progress of the condensation reaction. . Industrially, such sampling tests can be performed in the laboratory to analyze the relationship between the reaction time and the progress of the condensation reaction, and can be performed by controlling the reaction time. Although it varies depending on the amount of reaction catalyst, usage fee, etc., for example, solid spherical furan resin can be obtained by adjusting the temperature of the reaction solution to a range of 50 to 100 ° C. and setting the reaction time to a range of 20 to 400 minutes. While the condensation reaction is allowed to proceed until it is formed, the condensation reaction can be stopped while the spherical furan resin produced has a thermosetting property. More preferably, the temperature of the reaction solution is set in the range of 60 to 80 ° C., and the reaction time is set in the range of 30 to 120 minutes.

  In the above, the condensation reaction is stopped in a state in which the spherical furan resin has a thermosetting property in forming the spherical furan resin in a solid state, but the present invention further proceeds the condensation reaction to generate By continuing the reaction until the spherical furan resin becomes insoluble and infusible, a completely cured furan resin is obtained. Here, with the furan resin insoluble and infusible, “Kyoritsu Publishing Co., Ltd.” issued “Chemical Dictionary”, “Industrial Research Association Co., Ltd.” issued “Plastic Dictionary”, Iwanami Shoten Co., Ltd. published “RIKEN Dictionary”, Plastic Corporation・ The items of “Thermosetting property” and “Thermosetting resin”, such as “Used plastic term dictionary” published by Age, “The science and technology dictionary” issued by Nikkan Kogyo Shimbun Co., Ltd., and “The chemical term dictionary” issued by Giho Doho As described in the above, it refers to a state in which the furan resin is crosslinked and cured. For example, when the amount of dissolution when furan resin is dissolved in tetrahydrofuran is 5% by mass or less, the furan resin can be in an insoluble and infusible state. The reaction time was set as described above to stop the condensation reaction while the spherical furan resin had a thermosetting property, but by continuing the reaction beyond this time, the sphere completely cured to the insoluble and infusible state The furan resin can be easily obtained.

  The spherical furan resin thus completely cured to an insoluble and infusible state can be used as an organic filler or the like. Since spherical furan resin is in a spherical form, it can be used as a filler having excellent fluidity. For example, in addition to being incorporated as a filler in a plastic molding material, an adhesive, a paint, etc., it can also be used as an additive for toner, spacer for liquid crystal, material for forming pores of ceramic, core material for solder ball, etc.

  Further, it is possible to obtain a spherical carbon material by carbonizing the spherical furan resin which is completely cured and turned into an insoluble and infusible state by heat treatment and baking in a non-oxidizing atmosphere. The non-oxidizing atmosphere may be any one as long as the furan resin is not oxidized. For example, the inert gas atmosphere can be set to an atmosphere of argon, helium, nitrogen gas or the like. The conditions for the heat treatment are preferably set to about 400 to 3000 ° C. and about 1 to 100 hours for firing and carbonizing the furan resin.

  The spherical carbon material carbonized by the spherical furan resin has high electrical conductivity, thermal conductivity, and heat resistance. The conductive filler can be used taking advantage of these characteristics, and, for example, a conductive resin composition can be obtained by blending a spherical carbon material with various resins. Since the spherical carbon material is in the form of a sphere, it can be used as a conductive filler excellent in fluidity. By molding the conductive resin composition thus prepared by any method such as injection molding or compression molding, parts of electric and electronic devices having high conductivity and the like can be produced. In addition, it can also be used as a filler for thin film conductive films, filters, humidity control filters, condensation prevention plates, and the like.

  In addition, when the spherical furan resin is heat-treated in a non-oxidizing atmosphere as described above, the furan resin is thermally decomposed by being exposed to heat, and the decomposition product which has become a low molecular weight substance is volatilized and the escape thereof Since the marks become voids, a large number of pores are formed in the particles of the spherical carbon material obtained by carbonizing the spherical furan resin. For this reason, the spherical carbon material can also exhibit the same effect as activated carbon.

  Therefore, this spherical carbon material can be used as a carbon material for forming an electrode of a secondary battery such as a dry battery, a lead storage battery, or a lithium ion secondary battery. In preparing an electrode using a spherical carbon material as a carbon material for an electrode, for example, the spherical carbon material is dispersed in a solvent or the like together with a binder to form a slurry, and this slurry is applied to metal foil such as copper foil and dried. Can be performed by press molding or the like. Furthermore, this electrode can be used as a polarizable electrode to form an electric double layer capacitor that forms an electric double layer formed at the interface of the electrolytic solution. Thus, a secondary battery or an electric double layer capacitor having high charge / discharge capacity is obtained by producing an electrode for a secondary battery or an electric double layer capacitor polarizable electrode using the spherical carbon material of the present invention. It is possible to

  Here, as the polarizable electrode of the electric double layer capacitor, activated carbon having a large specific surface area is used as an electrode material so as to adsorb many ions, and the spherical carbon material according to the present invention is also fired and carbonized. It has pores with the same effect as activated carbon, and has a large specific surface area and pore volume. However, in the pores produced by carbonization of furan resin in this manner, the specific surface area and pore volume are not sufficiently large and are not always satisfactory.

Therefore, the specific surface area and pore volume per unit mass of the spherical carbon material can be obtained by activating the spherical carbon material by vapor phase activation with water vapor or carbon dioxide, chemical activation with molten potassium hydroxide, or the like. Further, spherical activated carbon having improved physical and chemical adsorption performance can be obtained. By producing an electric double layer capacitor polarizable electrode using such spherical activated carbon, an electric double layer capacitor having high charge / discharge capacity can be obtained.

  This spherical activated carbon can also be used for purification of water due to its high adsorption action. In addition, since the harmful substance is absorbed into the body if the harmful substance to be adsorbed is not adsorbed promptly in the digestive tract, an adsorbent having a high adsorption rate is required. Spherical activated carbon can be used as an oral adsorptive carbon agent for medicine because its physical and chemical adsorption performance is improved by increasing specific surface area and pore volume per unit mass by activation treatment. is there. For example, it can be used as a drug for treating chronic renal failure, a drug for treating gastrointestinal diseases such as Crohn's disease, a drug for treating ulcerative colitis and irritable bowel syndrome.

  Next, the present invention will be specifically described by way of examples.

(Reference Example 1)
In a 2 liter four-necked flask, 500 g of furfuryl alcohol and 750 g of water are charged, and further 15 g of gum arabic as a dispersant, 7-amino-4-hydroxy-2-naphthalene sulfonic acid as the reaction catalyst (the formula (12)) Charge 5g). Then, the stirring speed by a propeller type stirrer provided in the flask was set to 8 m / min, the temperature was raised to 85 ° C. in about 60 minutes, and the condensation reaction of furfuryl alcohol was carried out for 60 minutes. The pH of the reaction solution in the flask was 2.7.

The solution in the flask was initially nearly clear, but gradually became turbid and milky. After 60 minutes, the contents in the flask were cooled to 25 ° C. with stirring to stop the reaction. Next, the contents of the flask were filtered and the filter residue was spread on paper and dried at room temperature (25 ° C.) for 72 hours to obtain 376 g of spherical furan resin. The average particle diameter of the spherical furan resin was measured with a laser diffraction particle size distribution analyzer "LA-920" manufactured by HORIBA, Ltd. D ₅₀ (Particle diameter when the accumulated mass reaches 50%: average The particle size was 8.3 μm.
The melting point and the gelation time were measured for this solid furan resin. The measurement of the melting point was performed according to JIS K 6910 7.13, and the measurement of the gelation time was performed according to JIS K 6910 7.11, except that the temperature of the steel sheet surface was set to 110 ° C. The measurement results were a melting point of 77 ° C. and a gelling time of 21 seconds.

Example 1
In a 2-liter four-necked flask, 500 g of furfuryl alcohol and 750 g of water were charged, 15 g of gum arabic as a dispersant was charged, and 5 g of 7-amino-4-hydroxy-2-naphthalenesulfonic acid was charged as a reaction catalyst. . Then, the temperature was raised to 85 ° C. in about 60 minutes while stirring in the same manner as in Reference Example 1, and then the condensation reaction of furfuryl alcohol was continued for 5 hours.

  After this time, the contents in the flask were cooled to 25 ° C., the contents of the flask were filtered and the filter residue was spread on paper and allowed to dry at room temperature (25 ° C.) for 72 hours. Thus, 371 g of spherical furan resin having an average particle diameter of 8.2 μm was obtained. When this spherical furan resin was dissolved in tetrahydrofuran, it was found that the amount dissolved was 5% by mass or less, and thus it was confirmed that the resin was completely cured in an insoluble and infusible state.

(Example 2)
In a 2-liter four-necked flask, 500 g of furfuryl alcohol and 750 g of water were charged, 15 g of gum arabic as a dispersant was charged, and 7 g of 2-naphthalenesulfonic acid was further charged as a reaction catalyst. Then, the temperature was raised to 85 ° C. in about 60 minutes while stirring in the same manner as in Reference Example 1, and then the condensation reaction of furfuryl alcohol was continued for 5 hours. Thereafter, in the same manner as in Example 1 described above, 365 g of spherical furan resin having an average particle diameter of 7.5 μm was obtained. The spherical furan resin was tested for dissolution in tetrahydrofuran, and it was confirmed that the resin was completely cured to an insoluble and infusible state.

(Example 3)
500 g of furfuryl alcohol, 200 g of 37% by mass formalin and 650 g of water were charged in a 2-liter four-necked flask, 15 g of gum arabic as a dispersant, and 7 g of 2-naphthalenesulfonic acid as a reaction catalyst. Then, the temperature was raised to 85 ° C. in about 60 minutes while stirring in the same manner as in Reference Example 1, and then the condensation reaction of furfuryl alcohol and formaldehyde was continued for 5 hours. Thereafter, in the same manner as in Example 1 above, 401 g of spherical furan resin having an average particle diameter of 8.0 μm was obtained. The spherical furan resin was tested for dissolution in tetrahydrofuran, and it was confirmed that the resin was completely cured to an insoluble and infusible state.

(Example 4)
In a 2-liter four-necked flask, 500 g of furfuryl alcohol and 750 g of water were charged, 15 g of gum arabic as a dispersant, and 3 g of 7-amino-4-hydroxy-2-naphthalenesulfonic acid as a reaction catalyst. Then, the temperature was raised to 85 ° C. in about 60 minutes while stirring in the same manner as in Reference Example 1, and then the condensation reaction of furfuryl alcohol was continued for 7 hours. Thereafter, in the same manner as in Example 1 above, 366 g of spherical furan resin having an average particle diameter of 7.7 μm was obtained. The spherical furan resin was tested for dissolution in tetrahydrofuran, and it was confirmed that the resin was completely cured to an insoluble and infusible state.

(Example 5)
In a four-necked flask, 500 g of furfuryl alcohol, 200 g of 37% by mass formalin and 750 g of water are charged, and further 15 g of gum arabic as a dispersant and 5 g of 7-amino-4-hydroxy-2-naphthalenesulfonic acid as a reaction catalyst It is. Then, the temperature was raised to 85 ° C. in about 60 minutes while stirring in the same manner as in Reference Example 1, and then the condensation reaction of furfuryl alcohol with formaldehyde was continued for 5 hours. Thereafter, in the same manner as in Example 1 above, 368 g of spherical furan resin having an average particle diameter of 7.9 μm was obtained. The spherical furan resin was tested for dissolution in tetrahydrofuran, and it was confirmed that the resin was completely cured to an insoluble and infusible state.

(Example 6)
In a four-necked flask, 500 g of furfuryl alcohol, 80 g of 92% by mass aqueous paraformaldehyde solution, and 750 g of water are charged, and further 15 g of gum arabic as a dispersant and 7-amino-4-hydroxy-2-naphthalene sulfonic acid as a reaction catalyst 5g was charged. Then, the temperature was raised to 85 ° C. in about 60 minutes while stirring in the same manner as in Reference Example 1, and then the condensation reaction of furfuryl alcohol and paraformaldehyde was continued for 5 hours. Thereafter, in the same manner as in Example 1 above, 403 g of spherical furan resin having an average particle diameter of 7.6 μm was obtained. The spherical furan resin was tested for dissolution in tetrahydrofuran, and it was confirmed that the resin was completely cured to an insoluble and infusible state.

(Example 7)
A four-necked flask was charged with 500 g of furfuryl alcohol, 245 g of phenol and 750 g of water, and further 15 g of gum arabic as a dispersant and 5 g of 7-amino-4-hydroxy-2-naphthalene sulfonic acid as a reaction catalyst . Then, the temperature was raised to 85 ° C. in about 60 minutes while stirring in the same manner as in Reference Example 1, and then the condensation reaction of furfuryl alcohol with phenol was continued for 5 hours. Thereafter, in the same manner as in Example 1 described above, 576 g of spherical furan resin having an average particle diameter of 8.4 μm was obtained. The spherical furan resin was tested for dissolution in tetrahydrofuran, and it was confirmed that the resin was completely cured to an insoluble and infusible state.

(Example 8)
A four-necked flask was charged with 500 g of furfuryl alcohol, 245 g of phenol, 300 g of 37% by mass formalin and 750 g of water, and further 15 g of gum arabic as a dispersant and 7 g of 2-naphthalenesulfonic acid as a reaction catalyst. Then, the temperature was raised to 85 ° C. in about 60 minutes while stirring in the same manner as in Reference Example 1, and then the condensation reaction of furfuryl alcohol, phenol and formaldehyde was continued for 5 hours. Thereafter, in the same manner as in Example 1 above, 635 g of spherical furan resin having an average particle diameter of 8.3 μm was obtained. The spherical furan resin was tested for dissolution in tetrahydrofuran, and it was confirmed that the resin was completely cured to an insoluble and infusible state.

(Comparative example 1)
In a 2-liter four-necked flask, 500 g of furfuryl alcohol, 200 g of 37% formalin and 750 g of water were charged, 15 g of gum arabic as a dispersant was charged, and 5 g of m-xylene sulfonic acid was further charged as a reaction catalyst. Then, the temperature was raised to 85 ° C. in about 60 minutes while stirring in the same manner as in Reference Example 1, and then the condensation reaction was continued for 7 hours. However, even if the reaction is continued for 7 hours in this manner, the product remains liquid and no solid substance is obtained in the reaction solution, but only a highly viscous, water-containing one separated from water. The

(Comparative example 2)
In a 2-liter four-necked flask, 500 g of furfuryl alcohol and 750 g of water were charged, 15 g of gum arabic as a dispersant was charged, and 5 g of an 85% by weight aqueous phosphoric acid solution was charged as a reaction catalyst. Then, the temperature was raised to 85 ° C. in about 60 minutes while stirring in the same manner as in Reference Example 1, and then the condensation reaction was continued for 7 hours. However, even if the reaction is continued for 7 hours in this manner, the product remains liquid and no solid substance is obtained in the reaction solution, but only a highly viscous, water-containing one separated from water. The

  As in Examples 1 to 8 in which naphthalenesulfonic acids are used as a reaction catalyst, by extending the reaction time as compared with Reference Example 1, it is possible to obtain a solid spherical furan resin completely cured to an insoluble and infusible state. It was a thing.

Claims (6)

  A process for producing a spherical furan resin, which comprises forming an insoluble and infusible spherical solid furan resin by condensation reaction of furfuryl alcohol in the presence of a dispersant using naphthalenesulfonic acid as a catalyst.   The method for producing spherical furan resin according to claim 1, wherein a condensation reaction of furfuryl alcohol alone is carried out.   The method for producing a spherical furan resin according to claim 1, wherein a condensation reaction of furfuryl alcohol and an aldehyde is carried out.   The method for producing a spherical furan resin according to claim 1, wherein a condensation reaction of furfuryl alcohol and a phenol is carried out.   The method for producing spherical furan resin according to claim 1, wherein a condensation reaction of furfuryl alcohol, phenols and aldehydes is carried out.   The method for producing a spherical furan resin according to any one of claims 1 to 5, wherein the condensation reaction is carried out until the spherical solid furan resin to be produced becomes insoluble and infusible.