JPS6317818B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for granulating 1,4,4a,9a-tetrahydroanthraquinones.

(Prior art and problems to be solved by the invention) 1,4,4a,9a-tetrahydroanthraquinone (hereinafter abbreviated as THAQ) and its nuclear substituted derivatives (hereinafter, including unsubstituted and nuclear substituted derivatives)
It is called THAQ class. ) is a useful compound that is not only a raw material for dye intermediates and anthraquinones, but also recently used as a pulp cooking aid.

When THAQs are used as pipe cooking aids, they are generally dissolved in an aqueous solution of caustic soda and used as an aqueous solution, but it is more economical to handle THAQs in solid form in order to transport them to each user. be.

However, THAQ powders are extremely easy to solidify. For example, if they are packed in 25 kg bags and stored in stacks of 10 layers, the THAQ in the lower bag will become very hard and solidify, and powdered THAQs will be dissolved in aqueous alkaline solution. When dissolved, there are drawbacks such as the generation of a large amount of dust, which significantly worsens the working environment.

In addition, THAQs are generally called Naftkin (hereinafter referred to as
Unless otherwise specified, 1,4-naphthoquinone is indicated. ) and conjugated dienes such as butadiene, but it is dehydrogenated by air or light, or enolized in the presence of some acid components to produce 1,4-dihydroanthrahydroquinone, and even 1,4-dihydroanthrahydroquinone. , 4-dihydroanthraquinone, etc., and is chemically unstable. This tendency is particularly strong for THAQs obtained using industrial naphthoquinone as a raw material. Therefore,
In order to store or handle THAQs stably, it is preferable to form them into pellets or the like. Regarding the molding method of such THAQs, there is a method of dry molding, such as molding with flaker etc.
9256) etc. are known. however,
This method requires a fairly large-scale nitrogen seal to prevent the raw material from being exposed to air and oxidized during molding. Additionally, the above Diels-Alder reaction is usually carried out in the presence of an inert solvent such as ortho-xylene, but the
It is difficult to mold the reaction solution containing THAQs unless most of the solvent is removed, for example, to at least 0.1% or less, and in order to remove such solvent, the solvent is generally removed by vacuum evaporation, but especially in industrial On a large scale, there is an industrial difficulty in that it takes too much time to remove the solvent to at least 0.1% or less using this reduced pressure evaporation method.

As a result of intensive research aimed at solving the problems of the conventional methods described above, the present inventors discovered for the first time a method of granulating THAQs that is extremely industrially advantageous, and thus arrived at the present invention.

(Means and effects for solving the problems) The present invention is directed to a melt containing THAQs (for example, 1,4,4a,9a obtained by reacting naphthoquinone and a conjugated diene in an inert organic solvent). - An essential requirement is to disperse the melt (obtained by distilling off a predetermined amount of solvent from a reaction solution containing tetrahydroanthraquinones as the main component) into fine particles in an aqueous medium while cooling and granulating it. .

As THAQs in the present invention, in addition to unsubstituted THAQ, for example, 2-methyl
THAQ, lower alkyl substituted THAQ such as 2-ethyl THAQ, and other nuclear substituted THAQ can be mentioned.

In the present invention, naphthoquinone as a raw material is generally an industrial grade product. As the naphthoquinone used in the present invention, it is preferable to use highly purified naphthoquinone from which acid components have been completely removed, but since it is expensive, industrial naphthoquinone is usually used. Industrial naphthoquinone is usually obtained by separating naphthoquinone from hot gas containing naphthoquinone, phthalic anhydride, and naphthalene obtained by catalytic gas-phase oxidation reaction of naphthalene, for example, by wet collection and separation using an aqueous medium. . To give an example, an aqueous slurry of naphthoquinone and phthalic acid obtained by washing and collecting the reaction product gas in the catalytic gas phase oxidation of naphthalene with water or an aqueous medium containing maleic acid and phthalic acid is heated to remove phthalic acid. It is dissolved in water, and then substantially only the naphthoquinone is extracted with an aromatic hydrocarbon such as toluene or orthoxylene in an inert organic solvent.
The naphthoquinone solution obtained in this way contains
Since it contains some organic acids such as benzoic acid and phthalic acid, it is washed with a weak alkaline aqueous solution or warm water to remove the organic acids. The naphthoquinone solution thus obtained is used in a Diels-Alder reaction with a conjugated diene such as butadiene. It is better to have less acid components in the naphthoquinone solution, especially
It is preferably 0.1% or less.

In the present invention, the conjugated diene is selected from conjugated dienes corresponding to THAQs obtained by the Diels-Alder reaction of naphthoquinone. For example, butadiene (1,3-butadiene),
Examples include isoprene and 2-ethylbutadiene.

When using an inert solvent in the present invention, a solvent that is inert to the reaction between naphthoquinone and a conjugated diene such as butadiene and that is relatively easy to distill off at 140°C or less under normal pressure or reduced pressure is used. Good to use. For example, ethanol,
Examples include alcohols such as propanol; chlorinated aliphatic hydrocarbons such as trichlene and trichlorethane; aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene. Since water-soluble solvents are difficult to recover, industrially preferred are lower aromatic hydrocarbons that are water-insoluble and can be easily removed, and ortho-xylene is particularly preferred.
That is, naphthoquinone is selectively extracted from the reaction product gas from the catalytic gas phase oxidation of naphthalene as a solution of the aromatic hydrocarbon in an inert solvent, further purified if necessary, and the resulting naphthoquinone solution is subjected to the Diels-Alder reaction. It is supplied as a raw material and reacted with diene. Next, by desolventizing the obtained reaction solution to a predetermined amount according to the purpose of the present invention, a THAQ-containing melt can be easily obtained.

Although the Diels-Alder reaction between naphthoquinone and a diene such as butadiene can be carried out without a solvent, it is generally carried out in the above-mentioned inert organic solvent. The Diels-Alder reaction is carried out by a known method, for example, adding a polymerization inhibitor such as t-butylcatechol and a diene such as butadiene in an amount of 1 mole or more relative to the naphthoquinone to a solution of naphthoquinone in an inert organic solvent, and reacting at 90 to 150°C. It can be carried out by a method of reacting and then removing butadiene. From the reaction solution thus obtained, if necessary, the solvent is removed until a predetermined amount of solvent is reached (of course, this operation can be omitted if the amount of solvent is a predetermined amount without desolvation). can be provided
A melt containing THAQs can be easily obtained.

In the present invention, the melt containing THAQs includes:
Although it may contain a predetermined amount of an inert organic solvent,
It can also be carried out in the absence of a solvent. The upper limit of the freezing point of the melt, including when a solvent is present, is generally below about 100°C, usually below 95°C, preferably below 90°C.
The lower limit is about 60°C or higher, preferably 70°C or higher, and more preferably 80°C or higher.

In addition, in melts containing a predetermined amount of inert organic solvents of the THAQ class, for example oxoxylene-containing melts, the ortho-xylene content is preferably about 0.2%.
- about 30%, more preferably about 8% - about 30%
%, particularly preferably about 10% to about 25%. If it contains an organic solvent like this,
Since the freezing point (or melting point) of the melt containing THAQs is much lower than that in conventional molding methods, the operating temperature in the granulation operation can be lowered (for example, about 90°C or less) compared to conventional molding methods. A further advantage is that thermal isomerization of 1,4-dihydroanthrahydroquinones to 1,4-dihydroanthrahydroquinones can be prevented, resulting in stable operation.

The method for distilling off the organic solvent from a solution of THAQs in an inert organic solvent is to
In the following, a method of removing the solvent by distillation or steam distillation is used, and the conditions at that time are determined depending on the type of organic solvent used. however,
In any case, in order to suppress enolization of THAQs, the solvent is removed at a temperature of 140° C. or lower, preferably 120° C. or lower, particularly preferably 100° C. or higher than the freezing point. In order to carry out solvent removal in the shortest possible time, e.g. using a thin film evaporator,
It can also be carried out batchwise or continuously with suitable residence times.

To carry out the method of the present invention, there is a simple method in which a predetermined amount of the aqueous medium and the THAQ-containing melt obtained as described above are cooled and granulated using a jacket, for example, while stirring; or for example the first
It is possible to use a continuous method as shown in the process diagrams of FIGS.

In the method according to the process diagram shown in FIG. The THAQ-containing melt is spouted, granulated, and allowed to fall in a cooling medium at an appropriate speed, giving a swirling flow if necessary, to cool and solidify. The aqueous medium for cooling is
It is led out from the conduit 4 and stored in the storage tank 5.
After passing through a pump 7 and being cooled in a cooler 8 to keep it at a constant temperature, it is introduced into the lower part of the cooling tower 1 through an introduction pipe 9 and circulated while being appropriately fluidized to prevent granulated particles from adhering. Ru. on the other hand,
The granulated product is taken out from the outlet pipe 10.

In addition, in the method according to the process diagram in FIG.
While stirring by b, the THAQ-containing melt is first jetted from the nozzle 3 into the cooling medium 2a of the cooling tank 1a to granulate it, and then introduced into the cooling medium 2b of the cooling tank 1b. Cool and solidify in stages. The obtained granules are separated from the outlet pipe 4 by a screen 12' and discharged from the outlet pipe 10. The coolant from which the granules have been separated is temporarily stored in a storage tank 5, and then passed through a pump 7 from a discharge pipe 6 to a cooler 8.
It is cooled by the inlet pipe 9 and recirculated to the cooling tank 1a.

The granulated material thus separated and discharged contains a predetermined amount of solvent and about several percent to several tens of percent of water, and can be dried as is or by a conventional drying method such as a vacuum rotary dryer or an inert gas such as nitrogen. The product is dried using a circulating dryer, fluidized bed dryer, etc.

Next, THAQ according to Figures 1 and 2
The specifications, operating conditions, and aqueous medium used for the nozzle 3 for spouting a melt containing 2-3 will be explained in detail.

The number of installed jet nozzles 3 may be one or more. The pore diameter of the nozzle 3 is generally about 0.1 to about 4
mmφ is preferred. If it is smaller than 0.1 mmφ, it will become a dripping flow and the production efficiency will be reduced, and if it is larger than 4 mmφ, it will be a smooth flow and the particles will not be sufficiently atomized.

The injection pressure is preferably 0.1 m water column or more. It is not sufficiently atomized below 0.1m water column.

The temperature of the THAQ-containing melt to be ejected varies depending on the solvent content of the melt and the type of THAQ, but is generally about 120°C or lower, usually about 100°C or lower, and even about 95°C. ℃ or less, especially about 80℃ to about 90℃
is preferred. The higher the temperature, the more enolization of THAQs progresses, causing problems such as the generated enol clogging the nozzle. The lower limit temperature may be at least the freezing point of the melt, as long as it does not interfere with the granulation operation.

The temperature of the aqueous medium used is approximately 10℃ below 70℃
above, usually about 60°C or less, 20°C or more, preferably 30 to
It is 50℃. At temperatures above 70°C, particles tend to fuse together, and at temperatures below 10°C, the THAQ-containing melt is rapidly cooled, resulting in an amorphous shape that adheres to walls without crystallization, making it difficult to handle. In order to obtain a good, durable granulation, it is usually preferable to maintain the upper part at a relatively higher temperature than the lower part. To this end, a relatively cold aqueous medium may be supplied from the bottom of the cooling tower, and if necessary, the aqueous medium may be discharged from the top and the granules from the bottom, while fluidizing the THAQ particles. . It can also be heated and cooled to adjust the temperature of the upper part.

The residence time required for the particles introduced into the water to disintegrate depends on the type of THAQ being injected, the content of the solvent,
The time should be selected appropriately depending on the temperature of the melt and the particle size to be produced, but it is about 30 seconds or more, preferably 60 seconds or more. The residence time may be long depending on the case, but long residence time reduces equipment efficiency and is not economical, so it is better to keep it short as long as there is no problem.
Within 60 minutes, usually within 10 minutes. For example, especially when there is not much fluidity, the height of the cooling tower needs to be about 4 to 5 m.

In addition, by raising the cooling medium at a constant speed from the bottom of the cooling tower and flowing the granules that accumulate at the bottom of the cooling tower, it is possible to prevent particles from adhering to each other, increase the cooling effect, and lower the height of the cooling tower. It is also effective to do so.

In the present invention, water is mainly used as the aqueous medium, but if necessary, THAQs and an inert salt such as sodium sulfate and a surfactant may be contained therein. As an inert salt, it is easily oxidized and isomerized under acidic or basic conditions.
Considering the reactivity of THAQs, neutral salts are preferred, and the surfactant may be any anionic, cationic or neutral surfactant as long as it is approximately neutral in an aqueous medium. Adding an appropriate amount of salt adjusts the specific gravity of the aqueous medium and is convenient for dispersing particles to be granulated or selecting the falling speed. Addition of a surfactant lowers the surface tension of water and improves the flow of the nozzle. Since the injection pressure can be lowered, this is extremely advantageous in actual operation.

Specific examples of neutral salts include sulfates such as sodium sulfate, potassium sulfate, and ammonium sulfate; nitrates such as sodium nitrate, potassium nitrate, and ammonium nitrate; and chlorides such as sodium chloride, potassium chloride, and ammonium chloride. Sugars such as starch and glucose can be used in the same way as salt. The amount used is preferably such that the granules do not float, that is, the specific gravity of the aqueous medium is approximately 1.25 or less.

Specific examples of surfactants include aliphatic sulfonates such as dioctyl sulfosuccinate; aromatic sulfonates such as dodecylbenzene sulfonate, naphthalene sulfonic acid formalin condensate, and lignosulfonate; polyoxyethylene octadecyl Amine salts; cationic surfactants such as trimethyl-hexadecyl-ammonium bromide;
Nonionic surfactants such as ethers of ethylene oxide and higher alcohols, ethylene oxide derivatives of alkylphenol formalin condensates, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene glycol fatty acid esters, fatty acid alkanolamides; aminocarboxylate salts, Examples include amphoteric surfactants such as carboxybetaine type; and other known fluorocarbon surfactants such as fluoroalkyl carboxylates. The amount of surfactant used is generally 1 ppm to 1% based on the aqueous medium.

The method according to the process diagrams of FIGS. 3 and 4 will be explained below.

As in the method shown in FIGS. 1 and 2 described above, the method of inserting the tip of the nozzle for ejecting THAQ-containing melt into a cooling aqueous medium to form fine particles requires that the tip of the nozzle be cooled. The disadvantage is that the THAQ-containing melt tends to solidify and become clogged. As a method for solving this drawback, as shown in one embodiment of each of FIGS. 3 and 4, a cooling space 11 is provided above the cooling aqueous medium 2 in the cooling tower 1, and a cooling aqueous medium 2 is provided in the space 11. The medium is atomized by the cooling spray nozzle 12, and if necessary, an inert gas is further introduced into the medium, and the THAQ-containing melt is atomized from the spray nozzle 3, and the atomized particles are cooled in advance. , a method of dropping into the cooling aqueous medium 2 at the lower part, cooling and granulating, and the like. Such a method is preferable because it prevents the spray nozzle 3 from clogging due to cooling and solidification of the melt and also reduces the water content in the granules. In addition,
Cooling aqueous medium conduit 4, storage tank 5, outlet pipe 6, pump 7, cooler 8 and introduction pipe 9 in FIG.
The outlet tube 10 for the granulated product is used in the same manner as in FIG. 1.

The nozzle 3 for spraying the melt may be directed downward or upward. If it is directed downward, it may be atomized in space using the method described above, but if it is directed upward, it is best to atomize it while spraying with a conventional nozzle at a rate of about 0.1 to about 6 kg/cm ² G.

In addition, as a method for making the particles into fine particles, a method in which the melt is caused to fall onto a rotating disk as well as a nozzle, a method in which the melt is caused to collide with a wire mesh screen, etc. can also be adopted.

The method of spraying the aqueous medium in the upper space 11 of the cooling tower 1 can also be carried out by an appropriate method corresponding to the spraying direction of the melt. For example, if the nozzle for the melt is facing upward, the aqueous medium is sprayed at an appropriate distance from above, and if the nozzle for the melt is facing downward, for example, as shown in FIG. 3 or 4,
The aqueous medium is sprayed horizontally, diagonally, or upwardly below the aqueous medium to the extent that the two are in sufficient contact and that sufficient particles are retained when the liquid medium reaches the cooling medium liquid level in the lower part of the upper space 11. Consideration may be given so that the outside of the particle is cooled.

The supply ratio of the melt containing THAQs and the aqueous medium is
It may be in the range of 20-1:1-20, preferably 10-1:1-10.

The temperature of the aqueous medium may be the same as in the case of FIG. 1 above, and the other conditions can also be carried out in the same manner as in the case of FIG. 1 above.

(Example) Next, the present invention will be explained in more detail with reference to Examples. However, "%" used in this specification indicates "% by weight" unless otherwise specified.

Example 1 Butadiene was added to a 50% ortho-xylene solution of naphthoquinone obtained by a catalytic gas phase oxidation reaction of naphthalene, and 3 kg of a 60% solution of THAQ obtained by carrying out a Diels-Alder reaction was taken.
The ortho-xylene solvent was distilled off under reduced pressure at 100 Torr to obtain a THAQ melt containing 15% of the solvent.

2.1 kg of the obtained THAQ-containing melt was cooled to 85° C. and then granulated using an apparatus as shown in the process diagram of FIG. That is, the melt was placed in a container with an inner diameter of 240 mm and a height of
A back pressure of 0.5 m is applied to the 35°C cooling water 2 filled in a 4000 mm cooling tower 1 through a jet nozzle 3 with a hole diameter of 2.0 mm so that the linear velocity inside the nozzle is 1.7 m/sec.
It was introduced and dispersed under a water column for about 5 minutes. The sedimentation rate of the particles was 10 cm/sec for a particle size of 2 mmφ.
A pump (not shown) at the bottom of the cooling tower 1 was operated to give an upward flow of 3 cm/sec, and the granules were taken out from under the cooling tower while shaking the settled granules at the bottom of the cooling tower. The granulated material obtained from the lower part of the cooling tower 1 had a particle size of 0.1 to 2 mmφ, and after centrifugation, the water content and solvent content were each about 15%. The moisture and solvent contents in the product obtained by vacuum drying this granulated product at 70° C. and 50 Torr were 0.4% and 0.2%, respectively.

Example 2 2 kg of THAQ-containing melt containing 15% ortho-xylene solvent obtained in the same manner as in Example 1 was taken,
Granulation was carried out using an apparatus as shown in the process diagram of FIG. That is, in the cooling space 11 in the upper part of the cooling tower 1 having an inner diameter of 240 mm and a height of 5000 mm, the melt is sprayed in advance from below the melt spray nozzle 3 toward the water surface of the cooling water 2 in the lower part per unit time. While 5 to 10 times the amount of cooling water is being injected from the cooling medium spray nozzle 12, the melt is transferred to the nozzle 3 with a hole diameter of 2.0 mmφ.
The water was sprayed from a position 100 cm above the water surface under a back pressure of 1.5 m in the water column so that the linear velocity in the nozzle 3 was 4.0 m/sec. In this way, the THAQ-containing melt was introduced into the 35° C. cooling water 2 filling the lower part of the upper space 11 of the cooling tower 1 for about 2 minutes and dispersed therein. The settling velocity of particles is 10 for a particle size of 2 mmφ.
It was cm/sec. Operate the pump (not shown) at the bottom of cooling tower 1 to give an upward flow of 3 cm/sec.
The granules were taken out from under the cooling tower 1 while shaking the settled granules at the bottom of the cooling tower. The obtained granules had a particle size of 0.3 to 3 mmφ, and after centrifugation, the water content and solvent content were each about 12%.
The moisture and solvent content in the product obtained by vacuum drying this granule at 70°C and 50 Torr was 0.6, respectively.
% and 0.4%.

Example 3 2 kg of THAQ-containing melt containing 15% orthokylene solvent obtained in the same manner as in Example 1 was placed in a cooling tank with a capacity of 10 (diameter 18 cm, height 30 cm) equipped with a stirrer.
Then, 90°C hot water 4 was added, and the mixture was cooled at a cooling rate of 1.5°C/min using the jacket of the cooling tank while stirring. The granulated material became rice grain-like particles. When the contents were taken out and filtered, granules with a particle size of 2 to 3 mmφ were obtained. The water content in the granules was 10% and the solvent content was 15%. The granules were dried in the same manner as in Example 1 to obtain products with water and solvent contents of 1.0% and 0.4%, respectively.

Example 4 2 kg of THAQ-containing melt containing 15% ortho-xylene solvent obtained in the same manner as in Example 1 was poured into a pore size of 3 mm.
40 in a cooling tank equipped with an agitator from a spout nozzle of φ
It was sprayed in cooling water at 15°C for 2 minutes. After 10 minutes, remove the contents and strain to 0.5-1.0mmφ.
A granulated product was obtained. The moisture content of the granules was 7% and the solvent content was 15%. The granules were dried in the same manner as in Example 1, and the respective contents of water and solvent were determined.
Products of 0.3% and 0.2% were obtained.

Example 5 2-Methyl-THAQ2 obtained by Diels-Alder reaction between naphthoquinone and isoprene
Kg is melted at 85℃, and the melt is poured into a cooling tower whose height is
With the same equipment as in Example 1 except that the diameter was 10,000 mm, water was poured into water at 30°C from a jet nozzle with a hole diameter of 2.0 mmφ.
It was introduced into cooling water and dispersed under a water column with a back pressure of 0.6 m so that the linear velocity in the nozzle was 2 m/sec.
The particle size of the obtained granules was 0.3 to 2.5 mmφ.

(Effects of the Invention) As is clear from the above results, the present invention can produce the following remarkable effects of industrial value.

Since large-scale equipment is not required and it is a wet process, granulation can be performed more safely and easily than conventional molding methods.

There is no need to remove the solvent from the THAQ-containing reaction solution obtained from the reaction of naphthoquinone and conjugated diene in an inert solvent to a very small amount of 0.1% or less as in conventional molding methods, and it is possible to use it industrially. Particle size of 0.1 to 0.1 is easily obtained as a THAQ melt containing approximately 8% to 30% of solvent.
It can be molded into fine particles of 3 mmφ and granulated.

By including a solvent in the THAQ-containing melt, the freezing point of the melt can be lowered, and the operating temperature during granulation can be lower than in conventional molding methods, making it easier to enolize THAQs. It can be prevented.

[Brief explanation of the drawing]

Figures 1 to 4 are process diagrams or partial schematic diagrams of one embodiment of the method of the present invention carried out by four types of continuous methods, and in the figures, 1 indicates a cooling tower or A cooling tank, 2 a cooling aqueous medium, 3 a jetting or spraying nozzle for a melt containing THAQs, 7 a circulation pump, 10 a granulated product outlet pipe, and 12 a cooling medium spray nozzle.

Claims (1)

[Claims] 1. 1,4,4a, characterized in that a melt containing 1,4,4a,9a-tetrahydroanthraquinones is cooled and granulated while being dispersed in the form of particles in an aqueous medium. , 9a-Method for granulating tetrahydroanthraquinones. 2 A melt containing 1,4,4a,9a-tetrahydroanthraquinones is sprayed into the space where the cooling aqueous medium is sprayed in the upper part, and is cooled while falling and dispersing in the lower cooling aqueous medium. Claim 1 characterized in that the method is granulated into fine particles by
The method described in section. 3 The melt containing 1,4,4a,9a-tetrahydroanthraquinones is mainly composed of 1,4,4a,9a-tetrahydroanthraquinones obtained by reacting naphthoquinone and a conjugated diene in an inert organic solvent. The method according to claim 1 or 2, which is a melt obtained by distilling off a predetermined amount of solvent from a reaction solution as a component. 4 The melt containing 1,4,4a,9a-tetrahydroanthraquinones contains 1,4,4a,9a-tetrahydroanthraquinone obtained by reacting naphthoquinone and butadiene in an inert organic solvent as the main component. The method according to claim 1 or 2, wherein the melt containing 1,4,4a,9a-tetrahydroanthraquinone is obtained by distilling off a predetermined amount of the solvent from the reaction solution. 5. The method according to claim 3 or 4, wherein the inert organic solvent is a lower aromatic hydrocarbon. 6 Lower aromatic hydrocarbons include benzene, toluene,
6. The method according to claim 5, wherein xylene or ethylbenzene is used. 7. The method according to claim 6, wherein the xylene is ortho-xylene. 8. The method according to claim 4, wherein the content of inert organic solvent in the obtained melt containing 1,4,4a,9a-tetrahydroanthraquinone is about 30% or less. 9 Content of inert organic solvent is about 0.2% to about 30%
The method according to claim 8. 10 Content of inert organic solvent is about 8% to about 30%
The method according to claim 9.