JP2014125450A - Decabromodiphenylethane particle and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decabromodiphenylethane particle having a very low content of free bromine and a very low coloring, and its production method.SOLUTION: A method of producing a decabromodiphenylethane particle comprises reacting diphenylethane with bromine in the presence of a bromination catalyst to obtain a decabromodiphenylethane particle of an average particle size of 50-500 μm, a content of free bromine of 400 wt.ppm or less and a YI value of 50-200 and crushing the particle to obtain a high-quality decabromodiphenylethane crystal of an average particle size of 1-10 μm, a YI value of 25 or less and a content of free bromine of 100 wt.ppm or less.

Description

  The present invention relates to decabromodiphenylethane particles useful as a flame retardant for synthetic resins and a method for producing the same.

  Decabromodiphenylethane crystals are widely used as flame retardants for synthetic resins. Decabromodiphenylethane is usually produced by using excess bromine as a solvent, brominating diphenylethane as a raw material in the presence of a bromination catalyst, taking it out as particles, and pulverizing the particles.

  For this reason, a lot of free bromine remains in the decabromodiphenylethane particles obtained after the bromination reaction of diphenylethane. This free bromine causes coloration of decabromodiphenylethane crystals. Furthermore, when this decabromodiphenylethane crystal is blended with a synthetic resin as a flame retardant, bromine is released by heating, resulting in the thermal stability of the synthetic resin. However, there is a problem that the working environment is remarkably deteriorated by the released bromine gas, and it is necessary to remove free bromine during the production process.

  Since the decabromodiphenylethane particles obtained by the reaction contain a lot of free bromine, the crystals are pulverized to remove bromine and heat-treated for a long time, or the crystals are washed with a solvent. The inefficient method had to be adopted.

  For example, Patent Document 1 discloses a method of grinding the obtained decabromodiphenylethane particles while heating. Specifically, pulverization is performed for 40 hours at a high temperature of 230 ° C. in order to remove free bromine remaining in the particles at 6000 ppm. In this method, since the content of free bromine in the particles is extremely high, it is necessary to pulverize at high temperature for a long time. In addition, high-temperature bromine gas is generated and the equipment is corroded. A device is required.

  Patent Document 2 discloses a method of washing a thick slurry of decabromodiphenylethane particles with an inert solvent such as acetone or toluene. In this method, since a large amount of solvent is used, there is a problem in terms of economy, such as the need to recover and recycle the used solvent. Moreover, the coloring improvement effect cannot be said to be sufficient.

  Patent Document 3 discloses a method of reducing the free bromine content in the resulting decabromodiphenylethane particles by using dibromomethane as a solvent when brominating diphenylethane and reducing the amount of bromine used in excess. It is disclosed. However, since the reaction is performed by diluting with a solvent, the productivity per volume of the reactor decreases. Furthermore, it is necessary to recover and regenerate the solvent used in the reaction, which is not suitable for industrial use.

  In Patent Document 4, molten diphenylethane and bromine are mixed at a high speed in a short time using a specially shaped mixer, and fed to a reactor containing bromine and a reaction catalyst, so that the content of free bromine in the particles is A method for obtaining less decabromodiphenylethane is disclosed. However, a mixer for mixing molten diphenylethane and bromine at a high speed is special, and since it is highly corrosive by hydrogen bromide generated by reaction with bromine, it is difficult to apply it as an industrial apparatus.

  Patent Document 5 discloses a method for recrystallizing decabromodiphenylethane using a solvent. In order to dissolve decabromodiphenylethane, a high temperature of 200 ° C. or higher is required, and diphenyl ether or diphenyl is used. Since the solvent used, such as ethane, is a solid at room temperature, filtration of decabromodiphenylethane crystals also requires high temperatures, requiring special equipment and complicated operations. There is also a problem that the loss and purity due to recrystallization are as low as 95% or less. Furthermore, it is necessary to recover the solvent after use, and there are many problems from an industrial viewpoint.

  Patent Document 6 discloses a method of supplying molten diphenylethane to a position below the liquid level of bromine at a speed of 50 to 800 cm / sec in a reaction vessel supplied with bromine and a bromination catalyst. When diphenylethane is supplied below the liquid level, a bromide of diphenylethane may be deposited and clogged at the outlet, resulting in a problem in operability.

  As described above, the conventional method has not yet reduced the amount of bromine in decabromodiphenylethane particles efficiently on an industrial scale.

Japanese Patent No. 2833727 Special table 2010-509346 International Publication No. 2011/016966 Pamphlet Japanese Patent No. 3895769 JP-T 8-510208 Japanese Patent No. 3368540

  An object of the present invention is to provide decabromodiphenylethane particles having a relatively large average particle size, a low free bromine content, and suppressed coloring, and a method for producing the same.

  If the color of decabromodiphenylethane is large, when used as a flame retardant, the color tone of the synthetic resin is deteriorated and the commercial value thereof is lowered.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that there is little residual free bromine content in decabromodiphenylethane particles, and a novel yellow index YI value measured with a color difference meter is in a specific range. We found decabromodiphenylethane particles. The particles are also found to react in the presence of a bromination catalyst without using a solvent, and to precipitate as particles by adding water and / or removing excess bromine. The present invention has been completed by finding the effect that the residual free bromine content in the crystal and the YI value can be effectively reduced simultaneously by crushing.

  That is, the present invention relates to decabromodiphenyl before pulverization, wherein the average particle size is 50 to 500 μm, the free bromine content in the particles is 400 wtppm or less, and the YI value is 50 to 200. Ethane particles. In addition, after the reaction of diphenylethane and bromine in the presence of a bromination catalyst, after holding for a sufficient time to complete the reaction, water is added and / or excess bromine is removed to precipitate decabromodiphenylethane particles. A method for producing decabromodiphenylethane particles characterized in that the YI value obtained by grinding the particles obtained by the production method to 1 to 10 μm is 25 or less, and the free bromine content in the crystal A decabromodiphenylethane crystal having a content of 100 wtppm or less is also within the scope of the present invention.

  According to the present invention, it is possible to provide decabromodiphenylethane crystals with improved crystal coloring and improved mixing and kneading properties with a synthetic resin.

  Hereinafter, the present invention will be described in detail.

  The average particle diameter of the decabromodiphenylethane particles of the present invention is 50 to 500 μm, the free bromine content in the particles is 400 wtppm or less, and the YI value is 50 to 200. Such decabromodiphenylethane particles having physical properties have not been known so far, and are decabromodiphenylethane particles first discovered by the present invention.

  The characteristics of the particles are that the particles can be easily separated from the water slurry, the particles are easily pulverized, and free bromine and other impurities that cause coloring can be easily removed by washing with water. Diphenylethane crystals can be formed. In addition, it is preferable that the average particle diameter of the particles is 50 to 300 μm because the separability from the water slurry is good and subsequent pulverization is easy. The free bromine content in the particles is 300 wtppm or less, and the YI value is preferably 50 to 180. Both the free bromine content and the YI value of decabromodiphenylethane crystals after pulverization and water washing can be efficiently reduced.

  A method for producing the novel decabromodiphenylethane particles will be described below.

  Decabromodiphenylethane is obtained by bromination of diphenylethane. Although a solvent can be used in the reaction, in the present invention, it is essential to use an excessive amount of bromine and to use unreacted bromine instead of the solvent. This can simplify the process and operation.

  Commercially available diphenylethane can be used as it is.

  The bromination reaction of diphenylethane can be performed by supplying diphenylethane little by little to a reactor in which bromine and a bromination catalyst are present. At this time, diphenylethane may be supplied after being melted to a melting point or higher, or may be supplied after being dissolved in raw material bromine.

  As bromine, commercially available bromine can be used as it is. If necessary, it can be used for the reaction after dehydration with concentrated sulfuric acid or distillation purification.

  As the bromination catalyst, Lewis acids such as anhydrous aluminum chloride, anhydrous aluminum bromide, anhydrous ferric chloride, anhydrous ferric bromide and the like can be used. Aluminum powder and iron powder can also be used in the same manner because they react with bromine and by-product hydrogen bromide to produce aluminum bromide and ferric bromide. Ferrous chloride and ferrous bromide may be used, and these become ferric salts during the reaction and become bromination catalysts. Preferred bromination catalysts are anhydrous aluminum chloride and anhydrous aluminum bromide.

  The amount of bromination catalyst to be used is preferably 1 to 20% by weight, preferably 4 to 15% by weight, more preferably 8 to 13% by weight, based on diphenylethane. When the amount of bromination catalyst is less than 1% by weight, the reaction proceeds insufficiently, and when it exceeds 20% by weight, it is uneconomical.

  Before the reaction (before starting the supply of diphenylethane), the bromination catalyst is added to 1/5 to 1/3 of the total amount used in the reaction vessel containing bromine, and the remaining diphenylethane is supplied or after the supply is completed. The amount is preferably added in two or more divided portions. As a more preferable example of the divided addition of the bromination catalyst, 1/3 of the total amount used is added before the reaction, 1/3 of the total amount used is added 5 to 60 minutes after the completion of the supply of diphenylethane, In this method, the remaining 1/3 is added after 60 minutes. More preferably, 1/4 of the total amount used is added before the reaction, 1/4 of the total amount used is added 5 to 60 minutes after the completion of the supply of diphenylethane, and 1 to the total amount used is further 5 to 60 minutes after that. / 4 is added, and the remaining 1/4 is added after 4 to 60 minutes. By adding the bromination catalyst separately in this way, decabromodiphenylethane particles that are suppressed in coloration and easy to grind can be obtained.

  Diphenylethane can be added either on the surface of the reaction solution or below the surface of the reaction solution, but the operation is easier if it is added on the surface of the reaction solution.

  The method of supplying diphenylethane to the reaction vessel may be directly supplied to the reaction vessel or may be added to reflux bromine and dissolved before being supplied to the reaction vessel. A preferred method is a method in which diphenylethane is dissolved and fed into the refluxing bromine returned to the condenser for refluxing bromine into the reaction vessel, and decabromodiphenylethane with high purity, which is suppressed in coloration and easy to grind. The effect obtained is increased. The molar ratio of bromine to diphenylethane in the refluxed bromine is in the range of 39 to 100 moles, preferably 39 to 60 moles. When the amount is less than 39 mol times, problems such as an increase in coloring of the decabromodiphenylethane produced and a blockage of the reflux line are likely to occur. On the other hand, when the amount is more than 100 mol times, the amount of bromine vapor increases, so that the condenser becomes larger than necessary or the supply rate of diphenylethane becomes slower than necessary, which is economically problematic.

  The diphenylethane may be supplied in powder form or heated and supplied in a molten state, but supply in a molten state with easy handling is preferred.

  The amount of bromine used is preferably equal to or greater than the total amount of the amount of brominated diphenylethane to form decabromodiphenylethane and the total amount of decabromodiphenylethane to be dissolved in the bromine solution. If too much bromine is used, the production efficiency is somewhat reduced. On the other hand, if the amount of bromine used is too small, fine decabromodiphenylethane crystals, nonabromodiphenylethane, and octabromodiphenylethane crystals are precipitated during the bromination reaction, resulting in some decrease in filterability and purity. In consideration of purity and economy, bromine is used in an amount of 25 to 100 mol times the total amount of diphenylethane. The range of 25 to 50 mole times is preferable.

  The reaction temperature at the time of feeding diphenylethane is preferably 51 to 61 ° C. More preferably, it is 52-58 degreeC. Although a temperature lower than 51 ° C. is applicable, if the temperature is lowered, the reaction becomes insufficient, and the purity of the decabromodiphenylethane particles after the reaction may decrease. In addition, when the temperature is higher than 61 ° C., the reaction rate increases, but the evaporation and condensation of bromine becomes intense, and the load of necessary heat energy increases. Moreover, a pressurizing operation may be necessary.

  The supply of diphenylethane to the reaction vessel is preferably performed over 2 to 8 hours, and a more preferable supply time is 3 to 5 hours. If the supply time is longer than 8 hours, the productivity is somewhat reduced. If the supply time is shorter than 2 hours, the amount of bromine volatilized with the by-product hydrogen bromide increases, and it is necessary to increase the capacity of the condenser for the condensation.

  In order to complete the bromination reaction after completion of the supply of diphenylethane, it is preferably maintained at a temperature higher by 1 ° C. or more than the reaction temperature at the time of supply of diphenylethane. The holding time is 0.5 to 8 hours, and a more preferable holding time is 3 to 5 hours. This time may be determined by the target purity of the resulting decabromodiphenylethane particles.

  After the reaction, a small amount of water is added to the reaction solution to deactivate the bromination catalyst. Thereafter, the reaction mixture is heated to recover bromine. The recovery rate is usually 1 to 24 hours. Further, if necessary, water may be further added during the recovery of unreacted bromine, and finally the reaction product may be recovered as a water slurry of decabromodiphenylethane particles.

  Decabromodiphenylethane particles are precipitated when water is added or when unreacted bromine is recovered. Although the average particle diameter of the particles can be adjusted according to the crystallization conditions at this time, it is preferably 50 to 500 μm, more preferably 50 to 300 μm, in order to facilitate separation from the water slurry and facilitate pulverization after separation. . The main crystallization conditions here are the rotation speed of stirring, the amount of water added, the unreacted bromine recovery rate, and the like.

  Usually, this water slurry is centrifuged or filtered under pressure, and the precipitated decabromodiphenylethane particles are washed with water. In this way, decabromodiphenylethane particles are obtained. The amount of water during washing is usually 0.1 to 10 times the amount of the particles.

  Next, in the present invention, the particles are pulverized to obtain decabromodiphenylethane crystals having an average particle diameter of 1 to 10 μm, a YI value of 25 or less, and a free bromine content of 100 wtppm or less. Although pulverization can be carried out either dry or wet, a wet method is preferred, and a greater effect can be obtained for removing bromine in the particles. This is presumably because bromine dissolves in water during pulverization and is separated from crystals. Examples of the pulverizer include a ball mill and a bead mill.

  The degree of pulverization is preferably 10 μm or less, more preferably 5 μm or less. However, for pulverization of less than 1 μm, a special pulverizer is used, or pulverization for a long time is required, and further, a long time is required for subsequent filtration and drying. That is, the pulverization degree is preferably 1 to 10 μm, more preferably 1 to 5 μm.

  The decabromodiphenylethane crystals after pulverization are obtained by filtration and drying. Drying is performed at a temperature around 120 ° C. for 1 to 20 hours, preferably 2 to 12 hours. According to this, free bromine in the decabromodiphenylethane crystal is almost removed, and there is no corrosion of the dryer.

  In addition, the YI value in the present invention means a yellow index measured by ASTM D1925. The term “during reaction” means that diphenylethane is being supplied to bromine containing a bromination catalyst, and “after reaction” means after the supply of diphenylethane to bromine containing a bromination catalyst is finished. means. The measurement of free bromine content was performed by ion chromatography. The average particle size indicates the particle size at 50% of the integrated value of the particle size distribution obtained by the laser diffraction / scattering method, and the GC purity is the purity by area% of decabromodiphenylethane obtained by gas chromatography. Indicates.

  The decabromodiphenylethane particles of the present invention have an average particle size of 50 to 500 μm, a free bromine content of 400 wtppm or less, and a YI value of 50 to 200. The particles are easily pulverized, the bromine content after pulverization and washing with water is low, the YI value can be reduced, the YI value is 25 or less, the coloring is low, and the free bromine content is 100 wtppm or less. Quality decabromodiphenylethane crystals can be obtained.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.

Example 1
A 1 L glass flask (reactor) equipped with a glass condenser and a stirrer was charged with 1400 g of bromine and 2.13 g of anhydrous aluminum chloride powder, and the flask was set in an oil bath. Then, under stirring, the oil bath was heated, the temperature in the flask was raised to 59 ° C., and bromine was refluxed.

  Next, 63.8 g of diphenylethane was charged into a glass dropping funnel and heated from the outside with a ribbon heater in a nitrogen stream to melt the whole amount. This molten diphenylethane was fed to the bromine reflux line over 4 hours.

  The temperature of the oil bath was adjusted so that the reaction temperature during feeding of diphenylethane was 52 to 53 ° C. Under these reaction conditions, the bromine: diphenylethane molar ratio in the reflux line is in the range of 39-47: 1 during the diphenylethane feed.

  30 minutes after the supply of diphenylethane was completed, 2.13 g of anhydrous aluminum chloride powder was added to the reaction solution, and 2.13 g was further added 30 minutes later.

  Immediately thereafter, the reaction temperature was raised to about 60 ° C. and held for 4 hours.

  Then, the condenser was changed to a Dean-Stark condenser, and excess bromine distillation recovery was started. An amount of water commensurate with the recovered bromine was fed to the reactor. When bromine was removed, decabromodiphenylethane particles gradually precipitated. Distillation was continued until the vapor temperature reached 100 ° C., and unreacted bromine was recovered to obtain decabromodiphenylethane particles as an aqueous slurry.

  Next, the water slurry of the particles was filtered under reduced pressure and washed with pure water to obtain particles. The particles had many coarse particles around 200 μm, the average particle size was 110 μm, and the free bromine content in these particles was 120 wtppm on a dry weight basis. The YI value was 88.

  The particles were pulverized by wet pulverization. 80 g of particles, 228 g of water, 3 mL of 5 wt% sodium hydroxide aqueous solution and 300 mL of zirconia balls having a diameter of 1 cm were charged into a 1 L polyethylene container, rotated at a speed of 100 revolutions / minute, and preliminarily ground for 4 hours.

  The pre-milled decabromodiphenylethane slurry was collected, filtered under reduced pressure, and 228 g of water and 400 mL of glass beads with a diameter of 1 mm were charged into a 1 L polyethylene container for 4 hours at a speed of 100 rpm. Further pulverization was performed.

  After fine pulverization, a slurry of decabromodiphenylethane is collected and filtered under reduced pressure. The wet cake, 228 g of water and 400 mL of glass beads having a diameter of 1 mm are charged into a 1 L polyethylene container and pulverized at a rate of 100 revolutions / minute for 4 hours. Went.

  After this pulverization operation was performed once again, the slurry of decabromodiphenylethane was filtered and recovered as a cake.

  This cake was dried at 120 ° C. for 12 hours to obtain decabromodiphenylethane crystals.

  It was a high-quality decabromodiphenylethane crystal having an average particle diameter of 3.8 μm, a GC purity of 98.5%, a YI value of 14, and a free bromine content of 47 wtppm.

Example 2
The reaction was carried out in the same manner as in Example 1 except that all the used amount (6.39 g) of anhydrous aluminum chloride as a bromination catalyst was initially charged. After completion of the addition of diphenylethane, the temperature of the reaction solution was raised to about 60 ° C. and held for 4 hours.

  The subsequent recovery operation and pulverization operation of decabromodiphenylethane were performed in the same manner as in Example 1. The average particle diameter of the obtained particles was 110 μm, the free bromine content was 250 wtppm, and the YI value was 100.

  The crystals after pulverizing and drying the particles according to Example 1 had an average particle size of 4.0 μm, a GC purity of 99.5%, a YI value of 16, and a free bromine content of 50 wtppm.

Example 3
The bromination catalyst was changed from anhydrous aluminum chloride to anhydrous ferric chloride, and the amount used was the same as the number of moles of anhydrous aluminum chloride in Example 1. Specifically, 2.59 g of anhydrous ferric chloride was charged before the start of the reaction, 2.59 g was added 30 minutes after the completion of the addition of diphenylethane, and 2.59 g was further added 30 minutes later. Other operations were performed in the same manner as in Example 1. The average particle size of decabromodiphenylethane particles obtained after the reaction was 100 μm, the free bromine content was 118 wtppm, and the YI value was 90.

  The crystals after pulverizing and drying the particles in the same manner as in Example 1 had an average particle size of 4.1 μm, a GC purity of 97.5%, a YI value of 13, and a free bromine content of 50 wtppm.

Example 4
The reaction was performed in the same manner as in Example 1 except that the reaction temperature was changed to 52 to 54 ° C. Under these reaction conditions, the bromine: diphenylethane molar ratio in the reflux line is in the range of 39-58: 1 while diphenylethane is fed.

  The decabromodiphenylethane particles obtained after the reaction also had 300-400 μm coarse particles, the average particle diameter was 180 μm, the free bromine content was 124 wtppm, and the YI value was 90.

  The crystals after pulverizing and drying the particles in the same manner as in Example 1 had an average particle size of 3.7 μm, a GC purity of 99.2%, a YI value of 13, and a free bromine content of 49 wtppm.

Example 5
In the same manner as in Example 1, bromine and anhydrous aluminum chloride were charged into the reactor, and diphenylethane was added in total over 4 hours. The reaction temperature was 52 to 53 ° C. as in Example 1. 30 minutes after the supply of diphenylethane was completed, 4.26 g of aluminum chloride was gradually added over 60 minutes.

  Then, after maintaining at about 60 ° C. for 4 hours in the same manner as in Example 1, excess bromine was recovered to obtain decabromodiphenylethane particles. The average particle diameter of the particles was 110 μm, the free bromine content was 130 wtppm, and the YI value was 92.

  The crystals after pulverizing and drying the particles in the same manner as in Example 1 had an average particle size of 3.9 μm, a GC purity of 98.0%, a YI value of 14, and a free bromine content of 43 wtppm.

Example 6
As in Example 1, bromine and anhydrous aluminum chloride were charged into the reactor. Anhydrous aluminum chloride (1.07 g) was gradually added 3 hours after the start of the supply of diphenylethane.

  After completion of the addition of diphenylethane, 1.07 g of anhydrous aluminum chloride was added, and 2.13 g was further added 30 minutes later.

  Then, after maintaining at about 60 ° C. for 4 hours in the same manner as in Example 1, excess bromine was recovered to obtain decabromodiphenylethane particles. The average particle size of these particles was 110 μm, the free bromine content was 160 wtppm, and the YI value was 94.

  The crystals after pulverizing and drying the particles in the same manner as in Example 1 had an average particle size of 3.9 μm, a GC purity of 98.6%, a YI value of 18, and a free bromine content of 45 wtppm.

  The decabromodiphenylethane particles of the present invention are used as an intermediate product for obtaining high-quality decabromodiphenylethane crystals having a low YI value of 25 or less and a low free bromine content of 100 wtppm or less. This high quality decabromodiphenylethane crystal can be widely used as a flame retardant for synthetic resins.

Claims (12)

Decabromodiphenylethane particles having an average particle size of 50 to 500 μm, a free bromine content of 400 wtppm or less, and a YI value of 50 to 200. The decabromodiphenylethane particles according to claim 1, having an average particle size of 50 to 300 µm, a free bromine content of 300 wtppm or less, and a YI value of 50 to 180. 2. The reaction of diphenylethane and bromine in the presence of a bromination catalyst, adding water to the product and / or removing excess bromine from the product to precipitate decabromodiphenylethane particles. Or a process for producing decabromodiphenylethane particles according to 2. 4. The method for producing decabromodiphenylethane particles according to claim 3, wherein the reaction between diphenylethane and bromine is maintained for 0.5 hour or more. The method for producing decabromodiphenylethane particles according to claim 3 or 4, wherein a bromination catalyst is added during and / or after the reaction of diphenylethane and bromine. 1 to 5 to 1/3 of the total amount of bromination catalyst used is charged before the reaction, and the remaining bromination catalyst is added during and / or after the reaction in two or more portions. Item 6. A process for producing decabromodiphenylethane particles according to Item 5. The total amount of bromination catalyst used is 1/5 to 1/3 before the reaction, and the remaining bromination catalyst is continuously added during and / or after the reaction. Process for producing decabromodiphenylethane particles. 8. The bromination catalyst according to claim 3, wherein at least one selected from the group consisting of anhydrous aluminum chloride, anhydrous aluminum bromide, anhydrous ferric chloride, and anhydrous ferric bromide is used. A process for producing decabromodiphenylethane particles according to claim 1. 9. The charging ratio of diphenylethane and bromine when contacting with the bromination catalyst is such that the amount of bromine with respect to diphenylethane is in the range of 39 to 60 mole times. Process for producing decabromodiphenylethane particles. The method for producing decabromodiphenylethane particles according to any one of claims 3 to 9, wherein the retention temperature after the reaction is higher than the reaction temperature. The method for producing decabromodiphenylethane particles according to claim 10, wherein the reaction temperature is 51 to 59 ° C, and the holding temperature after the reaction is 1 ° C or more higher than the reaction temperature. It is obtained by grinding the decabromodiphenylethane particles according to claim 1 or 2 and having an average particle diameter of 1 to 10 μm, a free bromine content of 100 wtppm or less, and a YI value of 25 or less. Characteristic decabromodiphenylethane crystal.