JP2010155803A - Production method of bisphenol compound particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method of a bisphenol compound particle having high strength. <P>SOLUTION: The method for producing the bisphenol compound particle comprises bringing a melt liquid of the bisphenol compound into contact with a cooling gas, where the concentration of fine particles of the bisphenol compound in the cooling gas is adjusted to 5.5 g/m<SP>3</SP>or lower. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing bisphenol compound particles. Specifically, the present invention relates to a method for producing bisphenol compound particles having high strength and less generation of fine powder.

Bisphenol compounds typified by bisphenol A are used as raw materials for engineering plastics such as polycarbonate resins or epoxy resins, and the demand thereof has been increasing in recent years.
Bisphenol compounds are usually produced by reacting a large excess of phenolic compounds with carbonyl compounds such as ketones and aldehydes in the presence of acidic catalysts, and removing and purifying unreacted raw materials and impurities from this reaction solution. Thus, a high-purity bisphenol compound is obtained.

  The bisphenol compound thus obtained is granulated and distributed as a product on the market. As a typical particle formation method, a bisphenol compound melt is dropped from the nozzle at the top of the granulation tower, and a cooling gas (gas) such as nitrogen or air is supplied upward from the bottom of the granulation tower, A method of producing spherical particles (hereinafter sometimes referred to as prills) having a diameter of about 1 to 2 mm has been performed by dropping and solidifying the melt while bringing the melt and gas into countercurrent contact. Particles produced in this way are packed and transported and distributed in flexible containers (flexible bags), paper bags, bulk containers, etc., but contact between prills when transporting bisphenol compounds, impact during filling, etc. As a result, some of the particles are pulverized, causing problems such as clogging and sticking in prill filling equipment and bulk containers, and fine fine particles not coming out of the container well. There is a need for prills.

As a technique for producing a high-strength prill, a method of adding other components to a bisphenol compound melt to form particles (for example, see Patent Documents 1 to 4) is known. As a result, the purity of the bisphenol compound is lowered, so that it is not suitable for a polycarbonate application or the like where a high-purity bisphenol compound is required.
Also, a method that defines conditions such as the temperature and flow rate of the cooling gas in the granulation tower (see, for example, Patent Document 5), and a method that defines the injection conditions and method for the melt in the granulation tower (see, for example, Patent Document 6, Patent) A method for producing high-strength bisphenol particles is also known by the literature 7). However, a method for producing higher-strength particles is required.
Japanese Patent Laid-Open No. 5-294869 JP-A-5-294870 Japanese Patent Laid-Open No. 5-294872 JP-A-6-040981 JP-A-6-107581 JP 2004-137193 A JP-A-2005-213190

  The present invention provides a method for producing bisphenol compound particles having high particle strength.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention, when producing bisphenol compound particles by bringing a bisphenol compound melt into contact with a cooling gas, contact the bisphenol compound fine powder with the bisphenol compound melt. As a result, it was found that the crystal form and / or the surface shape of the produced particles changed, and that they greatly affected the strength of the bisphenol compound particles. The change in these particles is correlated with the fine powder concentration of the bisphenol compound in the cooling gas, and the bisphenol compound melt is solidified in an atmosphere where the fine powder concentration of the bisphenol compound in the cooling gas is a predetermined value or less. It has also been found that strong bisphenol compound particles can be produced, and the present invention has been achieved.

That is, the gist of the present invention is a method for producing bisphenol compound particles by bringing a bisphenol compound melt into contact with a cooling gas, wherein the fine powder concentration of the bisphenol compound in the cooling gas is 5.5 g / m ³ or less. There exists in the manufacturing method of the bisphenol compound particle | grain characterized by being.

  According to the present invention, bisphenol compound particles having high strength can be produced.

The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and is not specified by these contents.
The bisphenol compound and its melt used for producing bisphenol compound particles according to the present invention are not particularly limited, and for example, those produced by a known method can be used. Examples of bisphenol compounds include various bisphenol compounds such as bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol AD, bisphenol P, and bisphenol S, and some of them are alkyl groups, aryl groups, cyano groups, amino groups, A bisphenol compound substituted with a functional group such as a carboxyl group, a carbonyl group, or a vinyl group or a halogen element can be used. Of these, bisphenol A is particularly preferable. Hereinafter, bisphenol A is taken as an example, and an example thereof is shown.
As a method for producing bisphenol A, a production method comprising the following steps is generally performed, but the applicable steps are not specified in these contents unless the effects of the present invention are impaired. Note that some steps may be omitted, other steps may be added, or the order of steps may be changed as necessary.

<Reaction step (A)>
In this step, bisphenol A is produced by a condensation reaction using acetone and a stoichiometric excess of phenol in the presence of an acid catalyst. The molar ratio of phenol and acetone (phenol / acetone) used in the reaction is usually 3 to 30, preferably 5 to 20. The reaction temperature is usually 50 to 150 ° C., and the reaction pressure is usually atmospheric pressure to 600 kPa (absolute pressure).
The raw material acetone is not particularly limited as long as it is of the same purity as industrially available acetone, for example, purified acetone newly supplied from outside the system, separated in the concentration step (B) described later Acetone obtained by further treating the unreacted acetone thus obtained in an acetone circulation step, a mixture thereof and the like. In addition, if the acetone used for the reaction contains alcohols such as methanol, the activity of the acid catalyst may be reduced. Therefore, it is preferable to use them after removing these alcohols.

As the phenol, commercially available commercially available products may be used as they are, but the impurities contained in the phenol are made heavy by treating with an acidic catalyst such as an acidic ion exchange resin, Phenol purified by separating and removing heavy components by distillation is preferably used.
As the acid catalyst, mineral acids such as hydrochloric acid and sulfuric acid, strong acid cation exchange resins, solid acids such as polysiloxane, etc. can be used, but corrosion of the apparatus, decomposition of the catalyst after reaction, catalytic activity, catalyst From the viewpoint of life and the like, a strongly acidic cation exchange resin such as a sulfonic acid type is preferable. In the case of using a strongly acidic cation exchange resin as an acid catalyst, for the purpose of improving selectivity and conversion rate, as an auxiliary catalyst, alkylthiol such as methanethiol and ethanethiol, sulfur-containing amine compound, mercaptopropionic acid, etc. It is preferable to add such a sulfur-containing compound during the reaction and / or to modify a part of the sulfonic acid group of the strong acid cation exchange resin with the sulfur-containing amine compound. In particular, it is preferable to use a strongly acidic cation exchange resin modified with a sulfur-containing amine compound such as aminoalkylthiol or pyridylalkylthiol. In the case of a sulfonic acid type strongly acidic cation exchange resin, the ratio of modification with a sulfur-containing amine compound is usually 2 to 60 mol%, preferably 5 to 30 mol%, more preferably 10 to the amount of the sulfonic acid group. ~ 20 mol%.

When using the above-mentioned strongly acidic cation exchange resin as an acid catalyst, the condensation reaction between phenol and acetone is usually carried out in a fixed bed flow system. In this case, the liquid space velocity of the raw material mixture supplied to the reactor is usually 0.2 to 50 / h, and the reaction temperature is 50 to 100 ° C.
In the case of using other solid acids, a promoter can be used in the same manner as the strong acid cation exchange resin.

<Concentration step (B)>
In this step, a low-boiling component is separated from the reaction mixture obtained in the reaction step (A) to prepare a crystallization raw material containing concentrated bisphenol A. The low boiling point component referred to here is a component having a lower boiling point than phenol, and examples thereof include unreacted acetone; by-product water; impurities such as alcohol and alkylthiol. Examples of the method for separating the low boiling point component include a method of distilling the reaction mixture using a distillation column and separating the low boiling point component from the top of the column. The bottom liquid is a component containing bisphenol A and phenol. One or a plurality of distillation towers can be used, but it is preferable to perform separation with one group.

  When distillation is carried out at normal pressure, it is usually carried out under conditions where the top temperature of the distillation column is not higher than the boiling point of phenol, but it is preferred to carry out distillation under reduced pressure. The vacuum distillation is usually performed at a temperature of 50 to 150 ° C. and a pressure of 50 to 300 mmHg. In this case, a part of the unreacted phenol contained in the reaction mixture may be extracted from the top of the column together with the low boiling point component. If desired, an additional distillation column may be used to remove phenols, or the concentration of bisphenol A may be adjusted by adding phenol. Depending on the crystallization conditions, this step may be omitted, and the reaction step generated in the reaction step (A) may be supplied to the crystallization-solid-liquid separation step (C). In addition, the density may be adjusted.

<Crystallization-solid-liquid separation step (C)>
In this step, a slurry containing an adduct of bisphenol A and phenol (hereinafter sometimes abbreviated as “adduct”) was formed by crystallization from the crystallization raw material obtained in the concentration step (B). Later, the liquid is separated into adduct and mother liquor. Although there is no restriction | limiting in particular as a crystallizer used when forming the slurry containing an adduct, Usually, a continuous crystallizer is used. Examples of the continuous crystallization apparatus include a cooling system crystallization apparatus using a jacket or an internal coil, an external circulation cooling crystallization apparatus, an evaporative cooling crystallization apparatus, etc., but in the present invention, an external circulation cooling system is used. A crystallizer and a jacket type crystallizer are preferably used. The external circulation cooling type crystallization apparatus is obtained by connecting a crystallization tank and a cooler arranged outside the crystallization tank through a circulation path including pipes, valves and the like. A multitubular cooler is preferably used as the cooler. Moreover, it is preferable to provide the dissolution tank or heater for melt | dissolving a microcrystal.

  The jacket-type crystallizer is a type of apparatus that has a jacket around a crystallizing vessel, passes a refrigerant through the jacket, and cools it through the wall of the vessel. A container equipped with a stirring blade or baffle in the container and capable of satisfactorily stirring the internal liquid is preferable. Moreover, it is preferable that any type has a draft tube inside for the improvement of a mixing property. In order to control the shape and size of the crystal, a classification device may be provided in the device or provided outside.

  In the cooling part, the crystal adheres to the wall surface due to long-term operation and the cooling efficiency decreases, so the crystal melting operation is performed by stopping the cooling at appropriate intervals and heating in the middle of the crystallization operation It is preferable to dissolve and remove the attached crystals. Moreover, the apparatus which can remove a crystal | crystallization from a wall surface physically by having a scraping part can also be used. Examples of the classifier include those using the difference in the sedimentation rate of the crystal depending on the shape and size of the crystal, and those utilizing the difference in the dissolution rate.

Examples of the solid-liquid separator used for separating the adduct and mother liquor include horizontal belt filters, vacuum rotary vacuum filters, pressurized rotary pressure filters, centrifugal filtration separators, centrifugal sedimentation separators, and the like. A hybrid centrifuge (screen ball decanter) and the like can be mentioned.
Moreover, you may obtain the crystal | crystallization of bisphenol A directly at this process by adjusting the composition of a crystallization raw material.

<Phenol removal step (D)>
In this step, phenol is separated from the adduct obtained in the crystallization-solid-liquid separation step (C) to obtain high purity bisphenol A. In the phenol removal step (D), the adduct is usually heated and melted at 100 to 160 ° C., and from the obtained melt, for example, one or several distillation apparatuses, thin film evaporators, flash evaporators, etc. are combined. Use to remove most of the phenol.
Further, in order to remove a trace amount of phenol remaining in the melt, after performing the above operation, the residual phenol is removed by steam stripping or the like at a temperature of 150 to 250 ° C. to purify bisphenol A. A method is also adopted. By this operation, residual phenol is removed to 1000 ppm by weight or less, preferably 300 ppm by weight or less, more preferably 50 ppm by weight or less.

<Particulation process (E)>
The high-purity and molten bisphenol A obtained as described above is granulated into product bisphenol A.
There are no particular restrictions on the method of granulating the melt. For example, the flaker type, jet type, and drop-on-plate type described in the granulation manual (1st edition, Japan Powder Industry Association, edited by Ohmsha (1975)), etc. A general particle forming method such as a casting mold can be used.
In general, in a large-scale production plant capable of producing bisphenol A of tens of thousands of T / Y or more on an industrial scale, a spraying-type particle formation method using a granulation tower is adopted as the particle formation method, and the diameter is 0.6 to 4 mm. A degree of particles are produced. The typical example of the atomization by the injection type using a granulation tower is as follows.

  The melt of bisphenol A is ejected from a supply port provided above the granulation tower into the granulation tower through a metal plate having a plurality of nozzle holes. The inside of the granulation tower is in a cooling gas atmosphere at a temperature lower than the freezing point of the melt, and the jetted melt is gradually solidified into particles as it falls. The cooling gas may be retained or circulated in the granulation tower, but a method of circulating the inside of the tower by upflow so as to make countercurrent contact with the melt is preferable. The method of circulating the cooling gas includes a method of discharging and discarding the used cooling gas as it is (one-pass), a method of circulating the cooling gas, etc., but when nitrogen gas is used as the cooling gas, it is discharged from the granulation tower. It is also economically preferable to cool the cooling gas and circulate it to the granulation tower. Fine particles, giant particles, and the like are removed from the produced bisphenol A particles by sieving, and products are obtained as bisphenol A particles having a substantially uniform particle size.

  In addition, when the obtained bisphenol A is used for the production of polycarbonate resin by the melting method, it is transferred to the polycarbonate resin production process or the like in the molten state without being granulated as described in this step. You can also.

<Mother solution recovery system (F)>
Crystallization-The mother liquor separated in the solid-liquid separation step (C) is subjected to treatment such as isomerization and impurity removal for a part or all of the mother liquor, reaction step (A), concentration step (B), crystallization- Recycled to the solid-liquid separation step (C) and the like. The mother liquor to be recycled may be recycled to some or all of the steps (A) to (C) without being treated.
In the mother liquor, impurities such as 2- (2′-hydroxyphenyl) 2- (4 ″ -hydroxyphenyl) propane (hereinafter sometimes referred to as 2,4), which is an isomer of bisphenol A, and the like Although components such as heavy components are included, there are also many useful components such as bisphenol A and phenol, etc. Examples of methods for recovering these useful components include the following methods. This mother liquor is subjected to a reaction distillation in the presence of an acid catalyst or an alkali catalyst at 200 to 300 ° C. A fraction containing phenol and isopropenylphenol is obtained from the top of the tower, and tar is obtained from the bottom of the tower. Heavy component is discharged out of the system, and isopropenylphenol contained in the top fraction is easily polymerized and causes coloration. The preferred molar ratio of alkenyl phenol is able to suppress side reactions such as polymerization and is diluted with phenol so that 40 or more.

  By passing a solid acid catalyst such as an acidic ion exchange resin through this column top fraction, phenol and isopropenylphenol react to produce bisphenol A. These are circulated and recovered in the reaction step (A), the concentration step (B), the crystallization-solid-liquid separation step (C) and the like. In order to improve the recovery rate of bisphenol A, isomerization is performed with an acid catalyst before the decomposition reaction, crystallization and solid-liquid separation are performed again, and the liquid after separating the obtained adduct crystals is used for the reactive distillation. May be provided. In this case, the obtained adduct crystal is preferably recovered by recycling to the concentration step (B) and / or the crystallization-solid-liquid separation step (C).

<Method for Producing Bisphenol Compound Particles of the Present Invention>
In the present invention, the bisphenol compound particles are produced by bringing the bisphenol compound melt into contact with the cooling gas, and the fine powder concentration of the bisphenol compound in the cooling gas is 5.5 g / m ³ or less. .

As the cooling gas used in the present invention, a cooling gas having a temperature lower than that of the melt of the bisphenol compound, particularly a cooling gas having a temperature lower than the freezing point of the bisphenol compound is used, and usually 10 ° C to 100 ° C, preferably 20 ° C. A cooling gas of ˜60 ° C. is used.
In order to cool the cooling gas, a heat exchanger such as a cooler is required. However, if the temperature of the cooling gas is lowered more than necessary, a heat exchanger having a large heat transfer area is required or a large amount of heat is required. It is not economical because it is necessary to use the refrigerant. On the other hand, if the temperature of the cooling gas is too high, the melt cannot be sufficiently cooled and may not solidify.

In addition, the type of cooling gas usually includes air, inert gas, etc., but when air is used, it depends on coloring of bisphenol compounds due to contact with oxygen in a high temperature state or dust generated in the tower. Since there is a risk of explosion, it is preferable to use an inert gas. Above all, it is particularly preferable to use nitrogen from the viewpoint of availability, handling, cost, and the like.
In the present invention, the fine powder concentration of the bisphenol compound in the “cooling gas to be brought into contact with the melt of the bisphenol compound” (the cooling gas inside the granulation tower and may be abbreviated as “atmosphere gas” hereinafter) is 5. 5 g / m ³ or less, preferably 4.5 g / m ³ or less, and usually 0.1 g / m ³ or more, preferably 0.5 g / m ³ or more, more preferably 1 g / m ³ or more. Particularly preferably, it is 3 g / m ³ or more. If it is within the above-mentioned range, the smaller the value, the higher the strength of the bisphenol compound particles, which is preferable. However, the concentration of the fine powder of the bisphenol compound in the atmospheric gas is too low, and the melt of the fine powder and the bisphenol compound In such a case, the bisphenol compound melt is difficult to solidify even in a supercooled state, and it may be difficult to form bisphenol compound particles.

  As described above, in the present invention, it is necessary to control the fine powder concentration of the bisphenol compound in the atmospheric gas. However, the cause of the fine powder mixed in the atmospheric gas is the contact between the solidified prills and / or the granulation tower wall. Such as pulverization by collision with a structure such as, aggregation of vapor generated during cooling of the prill, or formation of solid droplets and solidification when a molten liquid is ejected.

  The fine powder concentration of the bisphenol compound in the atmospheric gas is determined by sampling the cooling gas in the granulation tower and measuring the fine powder concentration, collecting the fine powder from the cooling gas discharged from the granulation tower, its weight and cooling It can be determined by, for example, a method obtained by calculation from the gas flow rate. However, the fine powder concentration of the bisphenol compound in the atmospheric gas is usually non-uniform in the granulation tower and sampling is difficult, so the fine powder is recovered from the cooling gas discharged from the granulation tower, and its weight And a method of calculating from the flow rate of the cooling gas is preferable because it is simple. As will be described later, in the examples of the present specification, the fine powder concentration of the bisphenol compound in the atmospheric gas is calculated by collecting the fine powder from the cooling gas discharged from the granulation tower and calculating the weight and the flow rate of the cooling gas. Asked.

The contact between the bisphenol compound melt and the cooling gas may be either countercurrent contact or cocurrent contact, but countercurrent contact is preferred in terms of cooling efficiency.
In the following, description will be made by taking as an example a case where “the cooling gas is caused to flow in an up flow so that the contact between the melt of the bisphenol compound and the cooling gas is a countercurrent contact”, which is a preferred embodiment of the present invention. Also in this case, the fine powder concentration of the bisphenol compound in the atmospheric gas can be determined by the concentration of the bisphenol compound in the cooling gas discharged from the upper part of the granulation tower. In this case, the bisphenol compound fine powder is recovered from the cooling gas discharged from the upper part of the granulation tower, and the weight and the flow rate of the cooling gas are measured. Specifically, as shown in the examples described later, the fine powder of the bisphenol compound captured by a bag filter or the like is collected, the total weight of the collected fine powder of the bisphenol compound is measured, and the operation is performed from the obtained total weight. The average weight S (g / h) of fine powder per unit time is calculated as “amount of fine powder”.

Furthermore, the fine powder concentration is calculated by dividing the obtained fine powder amount by the cooling gas flow rate W (m ³ / h) passing through the trapping site such as the bag filter.
The fine powder in the present invention has a particle diameter of 500 microns or less, and when the fine powder is not a clear spherical shape, the longest part of the fine powder is 500 microns or less. In the above-mentioned preferred embodiment of the present invention, “in the case where the cooling gas is allowed to flow in an upflow so that the contact between the melt of the bisphenol compound and the cooling gas is a countercurrent contact”, the fine powder flows in the granulation tower. This means fine particles of a bisphenol compound discharged from the upper part of the tower together with the cooling gas, and mainly has a particle size of 1 to 400 microns. In addition, when measuring the fine powder concentration by sampling the atmospheric gas from the granulation tower, those staying or floating in the granulation tower without falling or discharging correspond to the fine powder.

The “fine powder amount” is usually 1.5 × 10 ^{6 to} 4.5 × 10 ⁶ g / h, preferably 2.0 × 10 ^{6 to} 4.0 × 10 ⁶ g / h.
Hereinafter, a method for controlling the fine powder concentration of the bisphenol compound in the cooling gas will be described.
FIG. 1 is a schematic diagram of a representative example representing a system around a granulation tower. In FIG. 1, the system around the granulation tower captures the fine powder of the bisphenol compound (hereinafter sometimes simply referred to as “fine powder”) entrained by the granulation tower 1 and the cooling gas discharged from the granulation tower 1. A bag filter 2 for recirculation, a circulation blower 3 for recirculation of the cooling gas coming out of the bag filter 2, a cooler 4 for cooling the recirculated cooling gas, and a line connecting them, a bisphenol compound The melt supply line 5, the bisphenol compound melt supply port 6, the cooling gas supply port 7, and the granulation tower 1, a large particle size produced by agglomeration of the melt during granulation, The liquid is mainly composed of a vibrating screen 8 for removing the lump that is adhering to the wall of the granulation tower and solidifying and peeling off and mixed in. Tena (hereinafter, sometimes abbreviated as FIBC) 9 is installed.

  As the bag filter 2, a mechanical vibration type, a reverse pressure type, a pulse jet type, or the like is generally used. The bag filter 2 needs to remove fine powder from the filter periodically or intermittently because fine powder adheres to the filter and it becomes difficult for the cooling gas to pass through the continuous use. The removed fine powder is collected in the flexible container 9 installed below using a rotary valve and a screw conveyor.

  The bisphenol compound melt supply port 6 is provided above the granulation tower, and the bisphenol compound melt is ejected from, for example, a plurality of nozzle holes provided in a metal plate. The nozzle hole diameter is preferably in the range of 0.4 mm to 1 mm. The distance between the centers of the nozzle holes closest to each other in the metal plate is preferably in the range of 10d to 40d, where d is the nozzle hole diameter. Examples of the nozzle hole arrangement include a triangular arrangement, a square arrangement, and a staggered arrangement. If the distance between the nozzle holes is too short, the droplets of the melt of bisphenol compound discharged from the nozzle holes will coalesce without solidifying, resulting in a non-spherical solid or There is a possibility that the liquid droplets drop to the lower part of the granulation tower in a state where they do not solidify, causing a blockage trouble at the bottom of the tower. On the other hand, if the distance between the nozzle holes is too large, a large metal plate is required if the amount to be processed is the same, and accordingly, the granulation tower main body and the nozzle become large equipment, which is not economical.

  The tower height of the granulation tower 1 is usually 20 to 50 m. As the tower diameter of the granulating tower 1, a desired numerical value can be selected depending on the ability to treat the bisphenol compound, and those of 2 to 10 m are usually used. The cooling gas supplied from the cooling gas supply port 7 provided on the side surface below the tower of the granulating tower 1 rises in the tower. On the other hand, the bisphenol compound melt supplied from the melt supply port 6 provided above the tower through the bisphenol compound melt supply line 5 descends as droplets, and the bisphenol compound melt and the cooling gas flow. Counter current contact. The bisphenol compound particles cooled and solidified by countercurrent contact are discharged from the tower bottom.

Examples of the method for setting the fine powder concentration value of the bisphenol compound in the atmospheric gas to 5.5 g / m ³ or less include, for example, a method of setting the cooling gas supply rate to the inside of the granulation tower within a predetermined preferable range, and granulation. Examples thereof include a method of setting the feed rate of the bisphenol compound melt to the inside of the tower within a predetermined preferable range, a method of combining them, and the like. Here, the cooling gas supply speed from the cooling gas supply port 7 to the inside of the granulation tower is a speed when passing through the cooling gas supply port 7 (linear speed of the cooling gas).

  It is preferable from the viewpoint of cooling efficiency that the cooling gas supply port 7 is provided at the bottom of the granulating tower 1 or the side surface below the granulating tower 1 so that the cooling gas flows in the tower by upflow. The gas supply port 7 may be single or plural. When a plurality of the cooling gas supply ports 7 are provided at positions symmetrical with respect to the longitudinal central axis of the granulating tower 1, the drift of the cooling gas in the granulating tower is prevented, and a rectifying effect is obtained. This is preferable. The ratio of the cross-sectional area of the cooling gas supply port 7 to the cross-sectional area in the horizontal direction of the granulating tower 1 (the total value of the cross-sectional areas in the case of having a plurality of supply ports) is usually 1/10 to 1, preferably 1 / 5 to 1, most preferably 1/2 to 1.

It should be noted that the turbulence of the cooling gas can be suppressed by using a rectifying device or the like when circulating the cooling gas in the granulation tower, and as a result, the portion where the gas linear velocity is fast and slow in the granulation tower. This makes it difficult to produce a portion and makes it possible to narrow the velocity distribution of the cooling gas, which can prevent the fine powder from being raised due to the portion having a high gas linear velocity.
Examples of the rectifying device include regular packing, irregular packing, baffle or perforated plate. Furthermore, the cooling gas supply speed to the inside of the granulation tower is set within a predetermined range, and the tower diameter of the granulation tower 1 is set within a predetermined range, that is, the cooling gas supply speed and the tower diameter of the granulation tower are combined. This is also preferable because the velocity distribution of the cooling gas inside the granulation tower hardly occurs.

  Furthermore, it is preferable to provide a plurality of cooling gas supply ports 7 in the granulation tower 1 as described above. Hereinafter, a case where there are two cooling gas supply ports 7 will be described as an example. The granulating tower 1 is provided with two cooling gas supply ports 7 at positions symmetrical with respect to the longitudinal central axis of the granulating tower 1. By making the size of each supply port 7 into the same shape with almost the same area, and supplying approximately the same amount of cooling gas from each supply port 7, the cooling gases from opposite directions collide with each other in the granulation tower, The cooling gas flow in the tower is made uniform and rises in a state where the velocity distribution hardly occurs. As a result, the melt of the bisphenol compound is uniformly cooled and solidified over the entire area of the granulation tower, and the contact amount of the fine powder of the bisphenol compound with the surface of the melt of the bisphenol compound is spread over the entire area of the granulation tower. Since it becomes uniform, there is no individual difference in the strength of the bisphenol compound particles, which is preferable.

  The supply rate of the cooling gas to the granulation tower 1 is usually 0.5 m / s or more, preferably 1 m / s or more, more preferably 3 m / s or more, most preferably 5.5 m / s or more, Usually, it is 8.3 m / s or less, preferably 8 m / s or less, more preferably 7 m / s or less, and most preferably 6 m / s or less. If the cooling gas supply rate is too high, the amount of fine bisphenol compound powder in the granulation tower increases, that is, the fine powder concentration of the bisphenol compound in the atmospheric gas exceeds the specified range of the present invention, and the droplets Since the amount of fine powder that comes into contact with the surface of the melted bisphenol compound becomes large, it is not preferable because it is impossible to produce bisphenol compound particles having high strength. Although depending on the droplet size of the bisphenol compound melt, if the cooling gas supply rate is too slow, the cooling gas flow rate is usually reduced and the cooling capacity is reduced. May not solidify.

The cooling gas flow rate can be arbitrarily selected depending on the amount of the bisphenol compound melt to be cooled, the temperature difference between the bisphenol compound melt and the cooling gas, and is usually 0.5 × 10 ⁵ m ³ / h. Or more, preferably 1 × 10 ⁵ m ³ / h or more, more preferably 3 × 10 ⁵ m ³ / h or more, and usually 8.3 × 10 ⁵ m ³ / h or less, preferably 8 × 10 ⁵ m ³ or less. / H or less, more preferably 7 × 10 ⁵ m ³ / h or less. If the flow rate of the cooling gas is too small, the bisphenol compound melt tends to be hard to solidify sufficiently, and if it is too large, the cooling gas cooler 4 tends to be large.

When the cooling gas is circulated and used as shown in FIG. 1, the cooling gas supply amount is about 10 to 20% smaller than the cooling gas flow rate.
The linear velocity of the cooling gas inside the granulation tower is usually 0.5 m / s or more, and usually 1.5 m / s or less. When the cooling gas is circulated and used as shown in FIG. 1, the fact that the linear velocity of the cooling gas is too slow inside the granulation tower means that the flow rate (supply amount) of the cooling gas is small. In some cases, the cooling capacity is lowered and the melt of the bisphenol compound is not sufficiently solidified. On the other hand, if it is too fast, the generated fine powder does not fall and stays in the granulation tower, so that the amount of fine powder of the bisphenol compound increases inside the granulation tower. As a result, the fine powder concentration of the bisphenol compound in the atmospheric gas exceeds the specified range of the present invention, and the amount of fine powder that comes into contact with the surface of the melt of the bisphenol compound in the form of droplets increases, resulting in high strength. The bisphenol compound particles cannot be produced, which is not preferable.

  The feed rate of the bisphenol compound melt to the granulation tower 1 is usually 2 m / s or more, preferably 3 m / s or more, more preferably 3.8 m / s or more, and usually 5 m / s or less, preferably 4 .5 m / s or less. When the supply rate of the bisphenol compound melt is too high, the bisphenol compound melt tends to become mist when the jet liquid is ejected into the granulation tower through the nozzle holes and the formation of droplets tends to be insufficient. On the other hand, if it is too slow, the production volume will decrease. The supply speed of the bisphenol compound melt to the granulation tower is the speed when passing through the nozzle holes provided in the metal plate of the melt supply port 6.

By the above method, the value of the bisphenol fine powder concentration in the cooling gas can be 5.5 g / m ³ or less, and bisphenol compound particles with high strength and less fine powder can be obtained.
Thus, the bisphenol compound particles obtained by the method for producing bisphenol compound particles of the present invention are substantially spherical and have an average particle size of about 0.5 to 2.0 mm. The strength of the bisphenol compound particles (hereinafter sometimes referred to as prill strength) is usually 83 g weight / piece or more, preferably 85 g weight / piece or more, more preferably 87 g weight / piece or more, particularly preferably 90 g weight. / Piece, usually 500 g weight / piece or less.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited at all by the following Examples.
In the following examples and comparative examples, bisphenol compound particles were produced and evaluated using the apparatus shown in FIG. However, the granulation tower 1 has two cooling gas supply ports 7 connected at right angles to positions symmetrical to the longitudinal center axis on the lower side surface of the granulation tower, and in the vicinity of the supply ports. Is a structure with baffles installed to rectify the cooling gas.

(Example 1 Production of bisphenol compound particles (hereinafter sometimes referred to as “granulation”)
A melt of bisphenol A at 170 ° C. is ejected at a speed of 4.0 m / s from a nozzle hole of a metal plate having a large number of nozzle holes installed in a melt supply port 6 installed in the upper part of the granulation tower 1. I let you. On the other hand, nitrogen gas (cooling gas) was supplied from the two cooling gas supply ports 7 at the lower part of the granulation tower at a cooling gas supply speed of 5.8 m / s and extracted from the upper part of the granulation tower. The jetted bisphenol A melt was countercurrently contacted with the cooling gas introduced from the lower part of the granulation tower and solidified into small spherical particles (prills).

  The extracted nitrogen gas is passed through the bag filter 2 to capture the fine powder of the bisphenol compound. The nitrogen gas is circulated by the circulation blower 3, cooled by the cooling water by the cooler 4, and supplied to the granulation tower 1 again. The bisphenol A melt was used as a cooling gas. As the bag filter 2, a pulse jet type bag filter was used. The bisphenol A particles captured by the bag filter were collected by backwashing with nitrogen gas to collect the particles adhering to the filter in the flexible container 9. By measuring the weight of the recovered fine powder of bisphenol A and the cooling gas flow rate W that passed through the bag filter, the fine powder concentration in the cooling gas was calculated from the following equation.

Cg = S / W
Cg: Fine powder concentration in cooling gas [g / m ³ ]
S: Fine powder amount [g / h]
W: Cooling gas flow rate [m ³ / h]

The bag filter 2 was regularly backwashed, and fine powder of bisphenol A captured by the bag filter 2 was collected in the flexible container 9. A continuous operation was performed for a certain period of time, the weight of the fine powder collected in the flexible container 9 was measured, the average recovered amount per unit time was calculated, and the calculated value was defined as the fine powder amount (S). In this example, continuous operation was performed for 24 hours, and the amount of fine powder was measured. The amount of fine powder was 2.5 × 10 ⁶ g / h. The flow rate of the cooling gas that passed through the bag filter was 5.7 × 10 ⁵ m ³ / h, and the fine powder concentration in the cooling gas (atmosphere gas) was calculated to be 4.4 g / m ³ from the above formula.

  The granulated prill was discharged from the bottom of the granulation tower, and large particles were removed through the vibrating sieve 8. The sampling of the prill was stabilized for 1 hour under the operating conditions, and then the sample that passed through the vibrating screen 8 was collected. 10 g of the collected prill was taken out, and the prill having a large particle diameter was further removed with a SUS sieve (10 mesh). Thereafter, the prill having a small particle diameter was further removed with a 14 mesh sieve made of SUS to obtain a prill having a particle diameter of about 1180 to 1700 microns. The particle strength (prill strength) was measured by taking out 50 particles from the obtained prills and measuring them one by one with a digital force gauge (manufactured by Imada DPS-2R). The average value of the measurement results was found to be 91 g weight / piece.

(Example 2)
The same procedure as in Example 1 was performed except that the supply rate of the bisphenol A melt was changed to 3.0 m / s, the cooling gas supply rate was changed to 7.9 m / s, and the cooling gas flow rate was changed to 7.8 × 10 ⁵ m ³ / h. Thus, particles of bisphenol A were produced. After 24 hours of continuous operation, the amount of fine powder of bisphenol A is 4.1 × 10 ⁶ g / h, and the fine powder concentration of bisphenol A in the cooling gas (atmosphere gas) is calculated to be 5.3 g / m ^3. It was. The strength of the obtained bisphenol A particles was 86 g weight / piece.

(Comparative Example 1)
The same procedure as in Example 1 was performed except that the melt supply rate of bisphenol A was 3.7 m / s, the cooling gas supply rate was 8.5 m / s, and the cooling gas flow rate was changed to 8.4 × 10 ⁵ m ³ / h. Thus, particles of bisphenol A were produced. After 24 hours of continuous operation, the amount of fine powder of bisphenol A is 4.8 × 10 ⁶ g / h, and the fine powder concentration of bisphenol A in the cooling gas (atmosphere gas) is calculated to be 5.7 g / m ^3. It was. The strength of the obtained bisphenol A particles was 81 g weight / piece.

It is the schematic which shows an example of the apparatus which can be used by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Granulation tower 2 Bag filter 3 Circulating blower 4 Cooler 5 Melt supply line 6 Melt supply port 7 Cooling gas supply port 8 Vibrating sieve 9 Flexible container

Claims (4)

A method for producing bisphenol compound particles by bringing a bisphenol compound melt into contact with a cooling gas, wherein the fine powder concentration of the bisphenol compound in the cooling gas is 5.5 g / m ³ or less. Particle production method.   The method for producing bisphenol compound particles according to claim 1, wherein the contact between the bisphenol compound melt and the cooling gas is countercurrent contact.   The contact between the melt of the bisphenol compound and the cooling gas is performed in the granulation tower, and the supply rate of the cooling gas to the granulation tower is 0.5 to 8.3 m / s. Of producing bisphenol compound particles.   The contact between the melt of the bisphenol compound and the cooling gas is performed in the granulation tower, and the supply speed of the melt of the bisphenol compound to the granulation tower is 2 to 5 m / s. 2. A method for producing bisphenol compound particles according to item 1.

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