JP5754314B2 - Method for producing bisphenol A - Google Patents

Description

  The present invention relates to a method for producing high quality bisphenol A.

Since bisphenol A used as a raw material of polycarbonate is required to have high quality, it must be avoided that the product quality of bisphenol A is adversely affected by components eluted from abrasion powder and resin.
In the industrial production method of bisphenol A in which phenol and acetone are reacted to form bisphenol A, the purification of bisphenol A is performed by cooling and crystallizing the reaction solution to form an adduct of bisphenol A and phenol. This is done by separating the phenol from the adduct. In a crystallizer that generates crystals containing bisphenol A, since the crystals adhere to the cooling surface, a technique for scraping the crystals has been developed. Specifically, the attached crystals are scraped off with a scraper. Depending on the material of the scraper scraper, the crystal is difficult to scrape or the scraper scrape is worn out, so impurities are mixed into the product bisphenol A. There was a problem to do.

  As a method for solving this, there has been disclosed a method of using an ultra-high molecular weight polyethylene resin (hereinafter sometimes referred to as “HMPE resin”) as a scraper scraping piece (for example, Patent Document 1). . However, ultra-high molecular weight polyethylene resin is excellent in abrasion resistance, but the abrasion powder generated by abrasion is fine, and even if a filter is installed in the subsequent process, it will pass through the filter, resulting in the quality of the final product. There was a problem that affected. Further, since the heat-resistant temperature is low, when scraping and removing bisphenol A and the like adhering to the scraper by steam cleaning, the scraper scraping piece itself melts, resulting in an increase in replacement frequency. Furthermore, in order to process ultra high molecular weight polyethylene into a shape like a scraped piece, there is a problem in that it is difficult to mold due to its properties (for example, Patent Document 2).

JP-A-6-345676 Japanese Patent Application Laid-Open No. 60-158876

The present invention provides a scraper for scraping off crystals adhering to the cooling surface of a crystallizer that produces crystals containing bisphenol A when producing bisphenol A, even when the melting point of bisphenol A is raised above the melting point. When it wears and wears, it becomes a wear piece that can be removed with a filter or the like, and by using a piece that has a scraping piece that is easy to mold itself, It is an object of the present invention to provide a method for producing high-quality bisphenol A, which can prevent elution of foreign matters and the like.

As a scraper that comes into contact with the heat transfer surface of the crystallizer main body, scale adhesion, etc. It has been found that the above problems can be solved by using a scraper made of polyvinylidene fluoride resin (hereinafter sometimes referred to as “PVDF resin”), and the present invention has been completed. That is, the gist of the present invention is as follows.
(1) In the manufacturing method of bisphenol A including the crystallization step of recovering bisphenol A by crystallization, a scraper for scraping off the crystals containing bisphenol A adhering to the cooling surface of the crystallizer body in the crystallization step A method for producing bisphenol A, comprising a scraped piece made of a silane-crosslinked high-density polyethylene resin or a polyvinylidene fluoride resin,
(2) The crystallizer is subjected to a solid-liquid separation step for separating crystals containing bisphenol A from the obtained slurry, and a filter is installed in any part of the process line after melting or dissolving the obtained product. A process for producing bisphenol A as described in (1) above,
(3) The method for producing bisphenol A according to (1) or (2), wherein the crystal containing bisphenol A is an adduct crystal composed of phenol and bisphenol A,
Exist.

  The present invention is a scraper for scraping off crystals adhering to the cooling surface of a crystallizer that generates crystals containing bisphenol A, and can maintain the shape even when the melting point of bisphenol A is raised. In this case, it becomes a wear piece that can be removed with a filter, etc., and by using a piece that has a scraping piece that can be easily molded by itself, it is possible to prevent wear powder from mixing into the liquid to be treated, foreign matter elution, etc. A method for producing high-quality bisphenol A can be provided.

  The present invention relates to a bisphenol A production method including a crystallization step of purifying bisphenol A by crystallization, and a scraper for scraping off crystals containing bisphenol A adhering to a cooling surface of a crystallizer body in the crystallization step. Is a method for producing bisphenol A, comprising a scraped piece made of silane-crosslinked high-density polyethylene resin or PVDF resin. Details are described below.

  The industrial production method of bisphenol A is a known method for producing bisphenol A by reacting phenol and acetone in the presence of a catalyst. Specifically, an excess amount of phenol and acetone are subjected to a condensation reaction in the presence of a strongly acidic ion exchange resin catalyst (hereinafter referred to as “condensation reaction step”), and the resulting bisphenol A, unreacted phenol, water After concentrating the reaction mixture containing the above (hereinafter referred to as “concentration step”), the adduct crystal comprising the adduct of bisphenol A and phenol is precipitated by cooling, and the adduct crystal is separated from the mother liquor (hereinafter referred to as “the concentrating step”). , "Crystallizing / solid-liquid separation process"), and then removing phenol from the adduct crystal (hereinafter referred to as "phenol removing process") and recovering bisphenol A to produce bisphenol A. Bisphenol A is granulated (hereinafter referred to as “bisphenol A granulation step”). Furthermore, bisphenol A is recovered from at least a part of the mother liquor as necessary (hereinafter referred to as “mother liquor treatment BPA recovery step”).

(A) Condensation reaction step The raw material phenol and acetone are reacted in a stoichiometric excess of phenol. The molar ratio of phenol to acetone is in the range of phenol / acetone = 3-30, preferably 5-20. The reaction temperature is usually 50 to 100 ° C. As the catalyst, a strongly acidic cation exchange resin such as a sulfonic acid type is used.

Although the manufacturing method of the said phenol includes the well-known method used normally, the phenol collect | recovered within a bisphenol manufacturing process can also be used. For example, a method described in JP 2010-189380 A is used.
The main form of the cation exchanger having a strong acid group is preferably a gel type. In addition, a porous type (a porous type, a high porous type, or a macroporous type) is also preferable from the viewpoint of ensuring substance diffusibility, resin durability, and strength. The gel type includes a simple gel type copolymer and an expanded network type gel copolymer, both of which can be used. On the other hand, the porous type is a porous copolymer, which can be used with any surface area, porosity, average pore diameter and the like. For the cation exchanger having a gel type or porous type strong acid group, a conventionally known method can be used. For example, “ion exchange resin, its technology and application” (published by Organo Corporation, revised edition, May 1986) 16th issue, pages 13 to 21).

  The size of the strongly acidic ion exchanger (hereinafter sometimes referred to as “catalyst beads”) and the modified strong acid type cation exchanger described below is such that the average particle size is usually 0.2 mm or more and 2.0 mm or less. The uniformity of the particle size distribution is usually 1.6 or less, preferably 1.5 or less. Further, as particularly preferred catalyst beads, catalyst beads having an average particle size of 30 to 650 μm, or modified strong acid cation exchanger described below are 50% or more of the whole, preferably 60% or more, more preferably 80% or more. Most preferably, it occupies 90% or more.

Such a catalyst bead and a method for producing the same may be any method as long as the catalyst bead having the above size can be produced. For example, a method described in International Publication No. WO2011 / 055819 is preferably used.
(B) Concentration step In this step, a crystallization raw material containing bisphenol A concentrated by separating low-boiling components from the reaction mixture obtained in the condensation reaction step is prepared. As used herein, the low boiling point component is a component having a lower boiling point than phenol. For example, unreacted acetone, by-product water, non-supported promoters such as alcohol, isopropylphenol, and alkylthiol contained as impurities. Examples include promoters when used. For example, the method described in JP2009-242316A is used.

(C) Crystallization-solid-liquid separation step and crystallizer In this step, a slurry containing an adduct is formed from the crystallization raw material obtained in the above step and then separated into an adduct and a mother liquor. As the crystallizer, a continuous crystallizer is usually used. As the continuous crystallizer, there are known cooling type crystallizers using jackets and internal coils, external circulation cooling type crystallizers, evaporative cooling type crystallizers, etc., but there is no particular limitation, but external circulation cooling type A crystallizer and a jacket type crystallizer are preferably used. The external circulation cooling type crystallizer is formed by a circulation path composed of piping, valves, etc., between the crystallization tank and a cooler arranged outside thereof, and a multi-tube type cooler is suitable as the cooler. used. Moreover, it is preferable to provide the dissolution tank or heater for melt | dissolving a microcrystal. The jacket-type crystallizer is a type that has a jacket around a container for crystallization, passes a refrigerant through the jacket, and cools it through the wall surface of the container. 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. 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. If necessary, heating can be performed during the crystallization operation, or a crystal dissolution operation can be performed. In such a case, a heat medium is used instead of the refrigerant.

Here, since crystals of bisphenol and a phenol adduct adhere to the cooling surface of the cooler of the crystallizer, it is preferable to install a scraper to be described later in order to scrape the crystals. This scraper has a scraping piece made of a silane-crosslinked high-density polyethylene resin or a polyvinylidene fluoride resin. The shape, size, installation location, and the like of the scraper can be appropriately selected by those skilled in the art so that the crystal can be scraped off.

The silane cross-linked high-density polyethylene resin is obtained by cross-linking a linear polymer polyethylene with silane to form a network polymer, and those having a gel fraction of 50% or more are preferably used. As a method for producing a scraped piece using the resin, it can be a known and commonly used method. For example, using the following linklon (registered trademark) or the like, the attached handling method can be used. Can be manufactured. As the resin, specifically, commercially available products such as Linkron (registered trademark) manufactured by Mitsubishi Chemical Corporation are used. High density refers to 0.94 g / cm ³ , more preferably 0.95 g / cm ³ . Moreover, since the scraping piece used in the present invention is often formed by extrusion molding, a grade suitable for the molding is preferably used. As the most suitable resin, manufactured by Mitsubishi Chemical Corporation, Linklon (registered trademark) XHE650N (density: 0.950 g / cm ³ , MFR (JIS K7210): 0.6 g / 10 min, ultimate gel fraction (xylene boiling point extraction) : 65%, tensile yield strength (JIS K7113): 25 MPa, tensile fracture strength (JIS K7113): 34 MPa, tensile fracture elongation (JIS K7113): 700%, flexural modulus (JIS K7113): 900 MPa) .

As the scraped piece made of polyvinylidene fluoride resin, a commercially available product can be used. Specifically, Quadrant Polypenco Japan, Polypenco (registered trademark) PVDF-SY (FM grade), etc. Is preferably used.
Examples of the solid-liquid separator include a horizontal belt filter, a rotary vacuum filter, a rotary pressure filter, a centrifugal filter separator, a centrifugal sedimentation separator, and a hybrid centrifugal separator (screen ball decanter).

  When silane-crosslinked high-density polyethylene resin is used for the scraping piece, the shape can be maintained even when the temperature of the scraping piece is raised above the melting point of bisphenol A. It is preferable to use a scrap that has a scraping piece that can be easily molded by itself, since it is possible to prevent wear powder from being mixed into the liquid to be treated, elution of foreign matters, and the like. When a polyvinylidene fluoride resin is used, the shape can be maintained even when the melting point of bisphenol A is raised or higher, and the replacement frequency can be reduced. In order to confirm the properties of the wear pieces, silane-crosslinked high-density polyethylene resin, polyvinylidene fluoride resin, and ultrahigh-molecular polyethylene resin were freeze-ground under the same conditions. Compared to the resin and the polyvinylidene fluoride resin, the ratio of fine powder of 100 μm or less was small.

(D) Phenol removal process In this process, phenol is isolate | separated from the adduct crystal obtained at said process, and bisphenol A is collect | recovered. In this phenol removal step (D), the adduct crystal is usually heated and melted at 100 to 160 ° C., and the obtained melt is used, for example, by using a distillation apparatus, a thin film evaporator, a flash evaporator or the like. A method of removing a portion of phenol is employed. In addition, a method of purifying bisphenol A by removing residual phenol by steam stripping or the like after the above operation is performed in order to remove a trace amount of phenol remaining in the melt. . This method is described in, for example, JP-A-63-132850 and JP-A-2-28126.

(E) Bisphenol A granulation step The high-purity, molten bisphenol A obtained as described above is sent to a granulation tower or a flaker, and becomes a solid prill or flake to become product bisphenol A. For example, when a granulation tower is used, molten bisphenol A is fed to the top of the granulation tower and sprayed from a number of holes provided in a nozzle plate installed at the top of the tower. The sprayed melt is cooled by a circulating gas rising from the bottom of the granulation tower, and is extracted from the bottom as a particulate solid called prill, and becomes product bisphenol A. Moreover, the obtained bisphenol A can be transferred to the next step in a molten state without being solid, as in the case where it is used for producing a polycarbonate resin by a melting method.

(F) Mother liquor treatment bisphenol recovery step Impurities generated in the process of producing bisphenol A by treating the mother liquor obtained by separation in the crystallization-solid-liquid separation step (C) by a known method. And bisphenol A can be recovered as a useful component. For example, as described in JP-A-2009-242316, there is a method of recovering bisphenol A by crystallization-solid-liquid separation after concentrating the mother liquor through an isomerization reactor. On the other hand, in this crystallization system, since the impurity concentration is high and the heat transfer efficiency is low, in the case of the jacket type crystallizer described in the crystallization-solid-liquid separation step (C), regeneration of crystal adhesion on the cooling surface and heat transfer. In order to improve the performance, those equipped with a scraper are preferred. In the crystallization system of the mother liquor-treated bisphenol recovery step, the scraper described in the crystallization-solid-liquid separation step (C) can be used particularly preferably. Examples of the crystallizer include a DP crystallizer provided by Tsukishima Kikai and a horizontal multi-stage cooling crystallizer provided by Kureha Engineering.

[Example 1]
A scraper that is installed so as to rotate in a horizontal direction in a state where it is pressed against the bottom surface and scraped against the bottom surface of the stainless steel (SUS304) container and pressed against the bottom surface of the container by a spring. A scraping piece abrasion test apparatus having a scrape was prepared. The scraper has a scraping piece of 55 mm × 110 mm × 6 mm. The scraping piece is made of silane-crosslinked high-density polyethylene resin (Mitsubishi Chemical Co., Ltd .: Linkron XHE650N) and PVDF resin (Nippon Polypenco). Polypenco (registered trademark) PVDF-SY (FM grade)) was used. The pressing force of the scraping piece on the bottom of the container was 0.5 N / cm. Since it was considered that the scraped piece was swollen by phenol, it was stored in phenol for 3 days and used in the experiment.

Phenol is charged into the container of the above test apparatus, the container temperature is set to 82 ° C., the maximum circumferential speed is 0.49 m / s, and the scraper is rotated in a pressure-bonded state to the bottom of the container. A single wear test was performed.
Ten days later, the scraped pieces were observed for surface wear using a Hitachi scanning electron microscope (model number: S3400N). As a result of observation, no abrasion of the scraped piece surface was observed in any of the scrapers of the silane-crosslinked high-density polyethylene resin and the PVDF (polyvinylidene fluoride) resin. In addition, when the weight change of the scraped piece was confirmed before and after the test, the scraped piece of the silane-crosslinked high-density polyethylene resin did not change at 32.1 g, but the scraped piece of the PVDF resin showed no change from 59.8 g. Increased to 60.0 g. (No decrease was observed.) It is considered that phenol entered and swollen into PVDF. From this result, it was found that the scraped piece made of silane-crosslinked high-density polyethylene resin had almost the same wear resistance as the scraped piece made of PVDF resin.

Further, with respect to the scraper having a scraped piece made of a silane-crosslinked high-density polyethylene resin, the same examination was performed in the case where the pressing force to the bottom of the container was 0.25 N / cm and 1.0 N / cm. In any case, however, no abrasion of the scraped surface was observed by a scanning electron microscope.
[Example 2]
A phenol solution containing 25% by weight of bisphenol A was charged into the container of the scraping piece abrasion test apparatus described in Example 1, dissolved in bisphenol A at 90 ° C., and stirred for 50 hours over 2 hours. The slurry solution was cooled to 0C. The scraper scraps were made of silane-crosslinked high-density polyethylene resin and ultra-high molecular weight polyethylene resin (HMPE) (Nippon Polypenco Co., Ltd .: U-PE100). The size of the scraping piece, the method of pressing onto the bottom of the container, and the pressing pressure were the same as in Example 1.

  With the scraper pressed against the bottom of the container, the circumferential speed of the maximum circumference was rotated at 0.49 m / s, and a scraper scraping wear test for 22 days was performed. After 22 days of testing, the scraped pieces were observed for surface wear using a Hitachi scanning electron microscope (model number: S3400N). As a result of observation, no abrasion was observed in any of the scrapers of the silane-crosslinked high-density polyethylene resin and the HMPE resin. As a result, it was found that the scraped piece made of silane-crosslinked high-density polyethylene resin in the slurry containing the adduct crystal composed of bisphenol A and phenol has wear resistance equivalent to that made of HMPE resin. .

Claims (2)

  In a method for producing bisphenol A including a crystallization step of purifying bisphenol A by crystallization, a scraper for scraping off crystals containing bisphenol A adhering to a cooling surface of a crystallizer body in the crystallization step is a silane crosslinking A method for producing bisphenol A, comprising scraping pieces made of high-density polyethylene resin or polyvinylidene fluoride resin. 2. The method for producing bisphenol A according to claim 1 , wherein the crystal containing bisphenol A is an adduct crystal composed of phenol and bisphenol A.