JP2017519886A - Method for producing spherical furan resin particles - Google Patents

Abstract

The present invention can significantly reduce the amount of aldehyde used by using a small amount of urea, and does not limit the pKa of the acid used, and is not an organic acid containing an inorganic acid or a benzene ring. The present invention relates to spherical furan resin particles that are easily produced using a low molecular weight organic acid and a method for producing the same. [Selection] Figure 1

Description

  The present invention relates to a method for producing spherical furan resin particles, and more specifically, a method for producing spherical furan resin particles by three-way mixing using furfuryl alcohol, aldehydes and urea, and the spherical furan resin obtained thereby. About.

Furan resin refers to furfural, a phenol-furfural resin obtained from furfuryl alcohol, furfural acetone resin, furfuryl alcohol resin, and the like. Furfural is a very useful general-purpose chemical that has been widely used in recent years for fine chemical intermediate materials, solvents, resin raw materials for special applications, and the like. Furfural is an aromatic aldehyde in which an aldehyde group CHO is bonded to a furan ring having a cyclic structure, the chemical formula is C ₅ H ₄ O ₂ , and furan-2-carbaldehyde or α-furanaldehyde fullerene. Also called flor.

  Furan resin (furfural resin, furfuryl alcohol resin) is a thermosetting plastic containing a furan ring, which is liquid in appearance but is cured by heat and used as a water-resistant adhesive. For example, when combined with nitrile rubber, a flexible furan resin can be obtained. It has excellent durability against oils, acids, alkalis, and solvents. It is possible to obtain a material having excellent properties for the corrosion resistance and heat resistance of furan resin and the adhesion and deformation of epoxy resin.

  Further, if graphite products are impregnated with furfuryl alcohol and then carbonized at 1,000 ° C. or higher, a product with low permeability is obtained. This is a special example of furan resin. Industrially produced are phenol-furfural resin and furfuryl alcohol resin. The former is produced by heating phenol and furfural in the presence of an alkali catalyst. Wood powder and hexamethylenetetramine are added to the resin and used as a molding material. In the latter, a furfuryl alcohol solution is heated in the presence of an acid catalyst to synthesize a liquid initial condensate, and when used, an acid catalyst is further added and cured.

  Various formulations of furan resins use an acid catalyst and are heated at a relatively low temperature to form an intermediate, and finally heat cured at a high temperature. Since it has excellent acid / alkali resistance, it is used as a reaction vessel in which glass fiber is reinforced as a resin cement to use acid / alkali, or as a backing to be applied to the inside of a storage tank. Furanyl alcohol (furfuryl alcohol), a low-viscosity furan resin, is soluble in alcohol, and high viscosity is partially soluble in alcohol. Ethyl acetate, acetone, aromatic hydrocarbons, furfural, furfuryl If it is dissolved in alcohol and neutral, it will be stable even after long-term storage. If an acid is added here, an insoluble cured resin can be obtained, and room temperature curing is possible depending on the type and amount of acid. The cured resin is resistant to acids, alkalis, organic solvents, and the like, but weakens as it hardens. Therefore, when forming a molded product, it must be used in combination with an appropriate filler or reinforcing material. When using a strong acid as a curing agent, it is necessary to select a filler. Carbon black, asbestos, diatomaceous earth, glass fiber, etc. are not affected by acid, so there is no problem, but wood flour, sawdust, paper, etc. I can not use it. The furfuryl alcohol precondensate is highly compatible with various plasticizers, thermoplastic and thermosetting resins, natural resins, synthetic rubbers, asphalts and the like, and may be used after being modified.

  When the furan resin is heated to furfuryl alcohol obtained by hydrogenation of furfural in the presence of an acid catalyst, a thermosetting furan resin excellent in chemical resistance is generated. In Japanese Patent Publication No. 2011-157463, a conventional self-condensation reaction using an acid catalyst such as an alkylbenzene sulfonic acid having a pKa of less than 1.5 in the presence of a protective colloid, using furfuryl alcohol alone. However, although a method for producing spherical furfuryl alcohol resin particles is disclosed and the use of aldehydes is excluded, there is a problem in that the pKa of the acid catalyst to be used must be limited.

  Japanese Patent Publication No. 2011-157464 discloses a method for producing spherical furan-aldehyde resin particles using an acid catalyst such as alkylbenzene sulfonic acid in the presence of a protective colloid of furfuryl alcohol and aldehydes. Japanese Patent Publication No. 2013-035781 discloses a spherical form formed by carbonizing spherical furan resin particles obtained by reacting furfuryl alcohol and aldehydes in the presence of a catalyst and a protective colloid. Although disclosed with respect to activated carbon particles, there is a drawback in that excessive amounts of aldehydes harmful to the human body are used, such as irritation to eyes, respiratory organs and skin.

  In addition, when resin is produced by using furfuryl alcohol alone or in combination, it emphasizes the use of inorganic acids or organic acids having a large molecular weight such as alkylbenzene sulfonic acid containing a benzene ring. So be careful when storing and using.

  In the mold industry field, a technique for using as a binder composition using furfuryl alcohol, aldehydes, and urea has been proposed. However, a resinous acid having a high molecular weight, the inorganic acid, or an organic having a high molecular weight. There is a problem that an excessive amount of acid is used as a curing agent, and further a silane coupling agent is further mixed after adding a curing accelerator, and finally mixed with a refractory granular material such as silica sand. Is different from the present invention in which spherical resin particles are produced and used.

  Therefore, the present inventor was researching to solve the technical and safety problems seen in the conventional furfuryl alcohol production method from furfuryl alcohol, and developed a safer production method of furan resin. The present invention has been completed.

  The present invention was conceived to solve the problems of the prior art, and the object of the present invention is not only to significantly reduce the amount of highly toxic aldehyde used, but also to limit the pKa of the acid catalyst. Furthermore, workability can be improved by using a low molecular weight acid catalyst with a simple structure that does not contain a benzene ring that has a harmful effect on the human body and is easy to handle. An object of the present invention is to provide a method for producing spherical furan resin particles.

  In order to achieve the above and other objects, the present invention includes (a) a mixing step in which a mixed solution of urea, furfuryl alcohol, and water is mixed in a reactor, and (b) the mixed solution having a pH of 7.5 to 9. A pH adjusting step for adjusting to 5; (c) a charging step for charging an aldehyde, an acid catalyst, and gum (Gum) into the reactor; and (d) a curing step for curing the furan resin. It is a manufacturing method.

  In the mixing step, the aldehydes are 0.01 to 0.25 moles based on the molar ratio 1 with respect to the furfuryl alcohol, and the urea is 0.02 to 0 based on the molar ratio 1 with respect to the furfuryl alcohol. .26 mol, water can be mixed at 0.5 to 15 times by weight with respect to 100 parts by weight of furfuryl alcohol.

  In addition, the acid catalyst may have 3 to 4 carbon water containing no benzene ring, and the acid catalyst is 0.1 to 10 parts by weight with respect to 100 parts by weight of furfuryl alcohol.

  Spherical furan resin particles are obtained by the above production method.

  In another example of the present invention, spherical activated carbon particles can be obtained by a carbonization and steam activation process for the manufactured spherical furan resin particles.

  According to the present invention, when producing spherical furan resin particles, the use of aldehydes can be remarkably reduced by mixing a small amount of urea, without using conventional inorganic acids or alkylbenzene sulfonic acids. Since the pKa value of the catalyst is not limited, the compressive strength of the furan resin particles produced thereby and the spherical activated carbon obtained thereby increases.

It is the photograph which expanded the spherical furan resin synthesize | combined in Example 1 and expanded 100 times.

It is the photograph which expanded and photographed the spherical furan resin synthesize | combined in Example 2 to 100 magnifications.

It is the photograph which expanded and photographed the spherical furan resin synthesize | combined in Example 3 in 100 magnifications.

It is the photograph which expanded and photographed the spherical furan resin synthesize | combined in the comparative example 1 to 40 magnifications.

  Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

  Throughout this specification, when a part “includes” a component, it does not exclude other components, but includes other components, unless specifically stated to the contrary. It means that you can.

  In the present invention, furfuryl alcohol is selected as an alternative to existing phenols, and urea is added to react to significantly reduce the use of highly toxic aldehydes. Alkylbenzene is not a strong acid such as sulfuric acid or hydrochloric acid. The present invention relates to a method for easily producing furan resin particles using an organic acid having a simple structure (eg, maleic acid or malonic acid) that is not an acid containing a benzene ring such as sulfonic acid.

  In order to reduce the amount of aldehydes used while maintaining the spherical shape of the resin particles, it has been found that the amount of aldehydes used can be significantly reduced by adding a small amount of urea as compared to the existing techniques.

  In addition, the production method in which the amount of aldehydes used is significantly reduced, so that the range of pKa does not have to be limited. Usually, inorganic acids known as strong acids and high molecular weights such as alkylbenzene sulfonic acids containing a benzene ring are included. Low molecular weight organic acids such as maleic acid (maleic acid, pKa = 1.9) and malonic acid (malonic acid, pKa = 2.8). Although it was discovered that the reaction can be performed using acid catalysts, this kind of organic acid is not liquid but has a merit that it is easy to store and use in a solid state.

  The aldehydes used in the present invention mean a compound containing an aldehyde group, or a substance used in producing such a compound or produced by reacting from such a compound. As such aldehydes, formaldehyde is preferably used. In addition, formaldehyde supply materials such as formalin, paraformaldehyde, trioxane, tetraoxane, and acetal are preferably used as the formaldehyde from the viewpoint of reactivity and raw material price.

  Urea used in the present invention is in the form of solid particles, and does not need to be particularly dissolved or powdered for the reaction. Since it is added to the reaction, it has good workability and is advantageous in terms of cost.

  The mixing ratio of the aldehydes and urea is 0.01 mol to 0.25 mol per mol of furfuryl alcohol (35 wt% formaldehyde aqueous solution 1 per 100 parts by weight of furfuryl alcohol, based on moles of aldehydes). To 22 parts by weight), preferably 0.07 to 0.18 moles (6 to 16 parts by weight of a 35% by weight formaldehyde aqueous solution with respect to 100 parts by weight of furfuryl alcohol).

  Urea is 0.01 to 0.26 mol (0.6 to 16 parts by weight to 100 parts by weight of furfuryl alcohol), preferably 0.08 mol, based on moles, based on moles of furfuryl alcohol. ˜0.19 mol (5 to 11.6 parts by weight based on 100 parts by weight of furfuryl alcohol). When the amounts of aldehydes and urea used are increased with respect to 1 mol of furfuryl alcohol, there is a problem that the generation of particles does not progress, the desired particles cannot be obtained, or the reaction rate is slow.

  The amount of water used in the present invention is about 0.5 to 15 times by weight with respect to 100 parts by weight of furfuryl alcohol. If the amount of water is less than 0.5 times by weight, the reaction product may harden into an oval shape, and if the amount used is more than 15 times by weight, the reaction time becomes long and it is difficult to use for production. Occur.

  In the present invention, the dispersion stabilizer acts on the surface during the dispersion process of the particles and is used for delaying the aggregation. Select one or more of water-soluble polymer type gums, methyl cellulose, hydroxyethyl cellulose and the like. Gum arabic is preferably used.

  The acid catalyst used in the present invention is generally used in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 4 parts by weight, based on 100 parts by weight of furfuryl alcohol. Used. The acid catalyst mentioned in the present invention is solid and does not need to be separately dissolved in water to form a solution, and may be mixed in the course of stirring during production. If the amount of the acid catalyst used is small, the reaction time may be long or the generated particles may be difficult to cure. If the amount used is large, lumps are generated or it is difficult to obtain the desired fine particles. Occurs.

  The base used in the present invention is for making the atmosphere of the initial reaction product a basic atmosphere. Bases such as sodium hydroxide, potassium hydroxide and barium hydroxide are used, and preferably sodium hydroxide is used. .

  The basic atmosphere used in the present invention has a pH of 7.5 to 9.5, preferably pH 8 to 9. If the pH is not basic, the initial reaction does not proceed. If the pH is too high, aldehydes may cause undesirable side reactions in the reaction.

  Although the temperature of 50 degreeC or more is used for the reaction temperature of this invention, Preferably it is 70 degreeC or more. The reaction time is appropriately applied in consideration of the reaction temperature, the state of the intermediate product, the state of particle hardening, etc., but generally about 2 to 30 hours are applied.

  Spherical furan resin particles are obtained by filtering, washing and drying the reaction product produced by the above method.

  When the spherical furan resin particles produced according to the present invention are carbonized and steam activated, porous spherical activated carbon with increased strength is obtained. The porous activated carbon with increased strength is carbonized and steam-activated spherical furan resin (carbonized by heating at a temperature of 500 ° C. for 1 hour, and using a rotary external heating furnace, It means porous activated carbon having a compressive strength of at least 10 N / sphere when heated at a temperature of 140 minutes. The strength of the porous activated carbon is at least 2 times to at most 10 times the strength of activated carbon produced from pitch as a raw material.

  In particular, in the case of porous activated carbon made from conventional pitch, since the compressive strength is extremely low, when trying to formulate a solid unit dosage form as a pharmaceutical product, for example, when filling a capsule, There was a problem that activated carbon was damaged. However, the oral adsorbent dose is close to several grams, so when it is taken in powder form, it often induces inconvenience of medication such as vomiting. It is the actual situation that administration is performed using auxiliary means such as. Therefore, since there is a need for a unit solid preparation that can greatly enhance the convenience of administration, in the present invention, a spherical furan resin having a high compressive strength is produced, and after carbonization and steam activation, a porous product is obtained as a result. It is a plan to obtain active spherical activated carbon.

  In the case of porous activated carbon using a conventional pitch as a raw material, the compressive strength is extremely low. Therefore, it can be said that the necessity for producing a spherical furan resin having a high compressive strength is high.

  The average particle diameter and compressive strength of the spherical activated carbon according to the present invention are measured by the following methods.

  (1) Average particle size

  A volume-based particle size cumulative diagram was created using a laser diffraction particle size distribution particle size analyzer (manufactured by Sympatec, HELOS Particle Size Analysis), and the particle size corresponding to the Volume Mean Diameter (VMD) was taken as the average particle size.

  (2) Strength measurement

  The strength of the spherical activated carbon was measured as follows using a compression strength machine (manufactured by Digitech, AFK-500TE).

  After placing one spherical activated carbon sample to be measured in the middle of the compression strength machine Tip, the compression strength machine is lowered at a speed of 20 mm / min, and the strength at which the first spherical activated carbon is destroyed is determined. The compressive strength value was used. Each of the 22 spherical activated carbon samples was measured by the method described above, and then the compression strength value was obtained by averaging the measured values of 20 particles excluding the maximum value and the minimum value.

  Hereinafter, the present invention will be described based on the following examples and comparative examples. The following examples and comparative examples are only for illustrating the present invention, and the present invention is not limited to the following examples and comparative examples.

Example 1

  Based on 100 parts by weight of furfuryl alcohol, 14 parts by weight of a 35 wt% formaldehyde aqueous solution, 10.5 parts by weight of urea and 130 parts by weight of water are mixed and stirred, and a small amount of 5 wt% sodium hydroxide aqueous solution is added to a pH of 8.5. And then stirred at 70 ° C. for 2 hours. After 2 hours, 100 parts by weight of furfuryl alcohol, 0.2 parts by weight of gum arabic, and 1.5 parts by weight of maleic acid are mixed and heated to 70 ° C., followed by further stirring for 2 hours. After stirring for 2 hours, the temperature is raised to 98 ° C., and the reaction is terminated after 8 hours. After completion, the reaction product is cooled to room temperature, filtered and washed to obtain spherical furan resin particles. The obtained spherical furan resin was measured at 100 magnifications using an image analysis program i-Solution (IMT i-Solution Inc.) and is shown in FIG.

Example 2

  Based on 100 parts by weight of furfuryl alcohol, 6.5 parts by weight of 35 wt% formaldehyde aqueous solution, 5 parts by weight of urea and 130 parts by weight of water are mixed and stirred, and a small amount of 5 wt% sodium hydroxide aqueous solution is added to pH 8.5. And then stirred at 70 ° C. for 2 hours. After 2 hours, 100 parts by weight of furfuryl alcohol, 0.2 parts by weight of gum arabic, and 1.5 parts by weight of maleic acid are mixed and heated to 70 ° C., followed by further stirring for 2 hours. After stirring for 2 hours, the temperature is raised to 98 ° C., and the reaction is terminated after 8 hours. After completion, the reaction product is cooled to room temperature, filtered and washed to obtain spherical furan resin particles. The obtained spherical furan resin was measured at 100 magnifications using an image analysis program i-Solution (IMT i-Solution Inc.) and is shown in FIG.

Example 3

  Based on 100 parts by weight of furfuryl alcohol, 14 parts by weight of a 35 wt% formaldehyde aqueous solution, 10.5 parts by weight of urea and 130 parts by weight of water are mixed and stirred, and a small amount of 5 wt% sodium hydroxide aqueous solution is added to a pH of 8.5. And then stirred at 70 ° C. for 2 hours. After 2 hours, 100 parts by weight of furfuryl alcohol, 0.2 parts by weight of gum arabic, and 1.5 parts by weight of malonic acid are mixed and heated to 70 ° C., followed by further stirring for 3 hours. After stirring for 3 hours, the temperature is raised to 98 ° C., and the reaction is terminated after 10 hours. After completion, the reaction product is cooled to room temperature, filtered and washed to obtain spherical furan resin particles. The obtained spherical furan resin was measured at 100 magnifications using an image analysis program i-Solution (IMT i-Solution Inc.) and is shown in FIG.

Comparative Example 1

  Based on 100 parts by weight of furfuryl alcohol, 30 parts by weight of 35 wt% formaldehyde aqueous solution, 22 parts by weight of urea and 130 parts by weight of water are mixed and stirred, and a small amount of 5 wt% sodium hydroxide aqueous solution is added to adjust the pH to 8.5. And then stirred at 70 ° C. for 4 hours. Four hours later, 100 parts by weight of furfuryl alcohol, 0.2 parts by weight of gum arabic, and 1.5 parts by weight of maleic acid were mixed and heated to 70 ° C., followed by further stirring for 3 hours. After stirring for 3 hours, the temperature is raised to 98 ° C., and the reaction is terminated after 15 hours. After completion, the reaction product is cooled to room temperature, filtered and washed to obtain spherical furan resin particles. The obtained spherical furan resin was measured at 40 magnifications using an image analysis program i-Solution (IMT i-Solution Inc.) and is shown in FIG.

Comparative Example 2

  Based on 100 parts by weight of furfuryl alcohol, 55 parts by weight of 35 wt% formaldehyde aqueous solution, 40 parts by weight of urea and 130 parts by weight of water are mixed and stirred, and a small amount of 5 wt% sodium hydroxide aqueous solution is added to adjust to pH 8.5. And then stirred at 70 ° C. for 4 hours. After 4 hours, 100 parts by weight of furfuryl alcohol, 0.2 parts by weight of gum arabic, and 1.5 parts by weight of maleic acid are mixed and heated to 70 ° C., followed by further stirring for 5 hours. After stirring for 5 hours, the temperature was raised to 98 ° C. and the reaction was terminated after 24 hours, but no substance was produced.

  The spherical furan resin particles obtained in Examples 1, 2, and 3 were carbonized by heating at 500 ° C. for 1 hour in a nitrogen atmosphere using an external heating rotary kiln, and the spherical carbon obtained here Spherical activated carbon was obtained by injecting water vapor in a nitrogen atmosphere using an external heating rotary kiln and heating the particles at a temperature of 900 ° C. for 140 minutes. This is called an activation process. The average particle size and compressive strength results for each example are listed in the table below.

  As is apparent from the above table, by mixing a small amount of urea, a very small amount of aldehydes can be used, and the pKa of the acid catalyst is high without using the inorganic acids and alkylbenzenesulfonic acids that have been presented. In addition, spherical furan resin particles having a high compressive strength could be obtained. Furthermore, the spherical activated carbon obtained from the spherical furan resin particles produced according to the present invention has a high compressive strength and is easy to handle.

  As described above, specific portions of the contents of the present invention have been described in detail. However, the present invention is not limited to those illustrated in the drawings. For those skilled in the art, such a specific technique is described below. It is clear that this is merely a preferred embodiment and is not intended to limit the scope of the invention. Accordingly, the substantial scope of the present invention is defined by the appended claims and their equivalents.

Claims (8)

(A) mixing a mixed solution of urea, furfuryl alcohol, and water in a reactor;
(B) a pH adjusting step for adjusting the mixed solution to pH 7.5 to pH 9.5;
(C) a charging step of charging aldehydes, an acid catalyst, and gum (Gum) into the reactor;
(D) a curing step of curing the furan resin, and a method for producing the furan resin.   In the mixing step, the aldehydes are 0.01 to 0.25 moles based on the molar ratio 1 with respect to the furfuryl alcohol, and the urea is 0.02 to 0 based on the molar ratio 1 with respect to the furfuryl alcohol. The method for producing a furan resin according to claim 1, wherein .26 mol and water are mixed in an amount of 0.5 to 15 times by weight with respect to 100 parts by weight of furfuryl alcohol.   The said acid catalyst has C3-C4 which does not contain a benzene ring, The manufacturing method of the furan resin of Claim 1 characterized by the above-mentioned.   The said acid catalyst is 0.1 weight part-10 weight part with respect to 100 weight part of furfuryl alcohol, The manufacturing method of the furan resin of Claim 1 characterized by the above-mentioned.   2. The method for producing a furan resin according to claim 1, wherein the aldehyde is one or more selected from the group consisting of formaldehyde, paraformaldehyde, trioxane, tetraoxane, and acetal.   A spherical furan resin particle produced by the production method according to any one of claims 1 to 5.   Spherical activated carbon particles obtained by carbonization and steam activation of the spherical furan resin particles of claim 6.   The spherical activated carbon particles according to claim 7 are orally administered adsorbents or fillers for chemical protective clothing.

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