JPH0564625B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing granules of 2-hydroxynaphthalene-3-carboxylic acid that have high industrial utility value. 2-Hydroxynaphthalene-3-carboxylic acid (hereinafter referred to as BON) has long been produced by a solid-gas phase reaction called the Kolbe-Schmidt reaction. He also invented a method of reacting a liquid mixture consisting of kerosene, sodium β-naphthol, and β-naphthol with carbon dioxide (Tokuko Sho
56-53296). According to this method, high quality BON such as melting point 220-221℃, purity 99.5%, β-naphthol sodium content 0.03%
is obtained. This BON is separated from the mother liquor through operations such as acid precipitation, filtration, and centrifugation, and after washing with water,
It is dried and used as an intermediate for pigments and dyes.
However, BON crystals generally contain very fine particles and are highly scattering. Furthermore, BON has a strong mucosal irritant property, which poses a major problem in handling. For example, when BON is used as an intermediate for pigments and dyes, if it is put into a reaction tank, the fine powder of BON will turn into dust and fly up. The fine BON powder that floats into the air does not settle easily and floats over a wide area, polluting the environment and irritating the skin and mucous membranes of workers, causing discomfort. In order to reduce such workability and safety problems during preparation, workers may wear dustproof glasses and masks, or use a filter to remove air by suctioning and degassing from a separate port from the raw material feeding port of the reaction tank. Methods such as collecting fine powder have been used, but they are not perfect. The reason why BON is highly scattering is because it contains very fine crystals, and it hardly dissolves in water, so phenomena such as moisture absorption hardly occur, and individual crystal particles aggregate and bond through adhering water. This is thought to be due to the fact that it is easy to move as individual fine particles in response to external shocks.
In order to suppress the scattering of substances having such properties, it is first possible to make the shape of the particles large enough to prevent them from scattering. For other compounds, a large crystal size may be used for this purpose, or a fine powder may be made into granules. but
Regarding BON, there is no such product on the market, and there are no reports of such an attempt being made. BON with a large crystal size can be obtained by selecting an appropriate solvent and recrystallizing it, but this is uneconomical because it is dissolved in the mother liquor or lost in the solvent. Moreover, large crystal diameters have a slow dissolution rate, so
It is inconvenient to handle when producing pigments and dyes.
The present inventors attempted to increase the apparent particle size of BON by a dry granulation method, but the granules obtained in this way had a slow dissolution rate and were not suitable for practical use. BON hardly dissolves in water (0.08 at 20℃
%), ordinarily, even if such materials are made into granules using a wet granulation method using only water as a binder, only brittle granules are produced, and even if the granules maintain their shape during granulation, they When it dries, most of it returns to its original fine powder form, making it useless as a granule. Generally, in such cases, good granules can often be obtained by appropriately adding a binder such as dextrin, gum arabic, or carboxymethyl cellulose together with a solvent such as water or alcohol, followed by kneading and granulation. However, since BON is a raw material for pigments and dyes, it cannot contain unnecessary binders that could become impurities. This is thought to be one of the reasons why BON granules were not well known until now. The present inventors attempted granulation using a mixed solution of water and lower alcohol as a binder, and by granulating from raw materials with a specific particle size composition, relatively good granules were obtained, and they were able to prevent scattering. the purpose has been fully achieved,
Moreover, it has been found that this method causes almost no increase in cost compared to the conventional manufacturing cost of fine powder BON. The present invention uses 100 parts by weight of 2-hydroxynaphthalene-3-carboxylic acid crystals containing 60% or more of particles with a particle size of 50 μ or less, and 5 to 25% by weight of lower alcohol.
This is a method for producing granules of 2-hydroxynaphthalene-3-carboxylic acid with significantly suppressed scattering properties, which is characterized by granulating and drying a mixture containing 18 to 33 parts by weight of water. The strength of the granules obtained by the method of the present invention includes:
As described later, the particle size of the BON particles is involved.
Therefore, it is necessary that 60% or more of the BON particles used as the raw material have a particle size of 50μ or less. The particle size of BON particles is determined by the concentration of BON sodium salt in the mother liquor during acid precipitation, the amount of tar, the amount of impurities such as unreacted β-naphthol, the concentration of mineral acid used for acid precipitation, the dropping rate, and the acid precipitation. It is affected by various conditions such as temperature.
Among these, the concentration of BON sodium, tar content, and the amount of impurities such as β-naphthol in the mother liquor are derived from the reaction conditions during BON production. In order to obtain BON with a desired crystal size by adjusting these conditions, it is preferable to manufacture by a continuous method. According to the continuous method, particle diameters within the above range can be easily prepared by setting reaction conditions. BON particles acid-precipitated by a batch method can also be used. When carrying out the present invention, first, the particle size is 50 μm.
18-33 parts by weight of water containing 5-25% by weight of lower alcohol is uniformly mixed with 100 parts by weight of BON crystal particles containing 60% or more of the following particles. If the total amount of water and organic solvent is less than this, it will not be possible to form it into granules, and if it is more than this, the surfaces of the granules will adhere to each other by the time the granules are dried, and they will harden into lumps, making it difficult to form them into granules. Granules cannot be formed. When mixing, a predetermined amount of water and a lower alcohol may be added to the dry powder of BON separately or as a mixture, but the water content is adjusted when centrifugally dehydrating the acid-precipitated BON, and a predetermined amount of water and lower alcohol are added to the dry powder of BON. The method of adding lower alcohols is economically advantageous. The water content to be adjusted during centrifugal dehydration and the amount of lower alcohol to be added can be easily determined by calculation. Using BON obtained in the acid precipitation process, dehydration, addition of lower alcohol, and kneading are continuously performed, since the BON crystal surface is wet, water and lower alcohol are added to the dried fine powder crystals. It is advantageous in that the kneading time can be shortened compared to when kneading with addition, and continuous granulation becomes easier. The ratio of lower alcohol to water needs to be 5 to 25% by weight of lower alcohol and 95 to 75% by weight of water. If the amount of lower alcohol is less than this, a sufficient granulation effect cannot be obtained. Moreover, if the amount is more than this, the granulation effect may decrease, which is also economically disadvantageous. BON, lower alcohol, and water can be kneaded using, for example, a kneader. As the lower alcohol, lower alcohols having a boiling point of 100° C. or less, such as methanol, ethanol, normal propyl alcohol, isopropyl alcohol, etc. are used. Among these solvents, methanol is the cheapest and economically advantageous. Lower alcohols can be mixed with water at any ratio, so they are easy to mix in when added to dehydrated BON, and they can be mixed with water at any ratio and dried.
It can be added to BON powder or undried BON that has been centrifugally dehydrated. Moreover, these lower alcohols have lower boiling points than water, so
When drying the granulated material, it is dried at a normal drying temperature without excessive heating. Next, the kneaded product is granulated and then dried to obtain the granules of the present invention. When granulating, the pore size
It is preferable to use an extrusion type granulator having a die of about 0.5 to 1.5 mm. The BON granules obtained in this way turn out to be surprisingly good granules, and do not return to the original finely powdered BON crystals even after being subjected to a fairly strong impact, and their scattering properties are suppressed. When the BON used for granulation was dried and the particle size was measured by the sedimentation method, it was 0 to 10μ.
2%, 10~20μ 13%, 20~30μ 28%, 30~
20% of particles are 40μ, 10% are between 40 and 50μ, and particles larger than 50μ
It showed a distribution of 27%. unexpectedly good like this
One of the reasons why BON granules were obtained is thought to be that the BON used for granulation has a wide particle size distribution and contains a relatively large number of fine crystals. Looking at the process of extrusion granulation, the raw material BON is mixed with an appropriate amount of water and lower alcohol, then kneaded, given physical properties suitable for granulation, and extruded through a die with an appropriate pore size. be done. At this time, extrusion pressure is applied to the raw material BON, and the crystals are pressed together and bonded together through a mixed solution of water and lower alcohol. Although BON hardly dissolves in water, it is relatively soluble in the lower alcohol mentioned above, so a part of the surface of the crystal particles dissolves in the mixed solution of water and lower alcohol, and the extrusion pressure causes the crystal particles to bond with each other. It is thought that they are combined. When granulating with only water instead of a mixed solution of water and lower alcohol, only granules that easily crumble after drying are produced.
However, the effect of this mixed solution on the bonding properties of crystal particles is not absolute, and it is thought that it contributes to a part of the bonding force. That is, the present invention
The strong bonding force between crystal particles in BON granules is
Since the crystal grain size distribution is wide and contains a relatively large number of fine crystals, the crystal grains are in a close-packed state during extrusion, and in addition, a part of the surface of the crystal grains is damaged by the mixed solution of water and lower alcohol. This is thought to be caused by melting, crimping, and bonding. As a comparative experiment to confirm this, granulation was attempted using BON with reduced fine crystals.
In other words, by classifying dried fine powder BON,
BON containing 70% particles with a particle size of over 50μ
was prepared. To 100 parts by weight of this product, 30 parts by weight of water containing 20% by weight of ethanol was added, thoroughly kneaded, and granulated using an extrusion type granulator having a die with a hole diameter of 1.0 mm. When this was dried, it retained a slight granule shape, but when a slight impact was applied, most of it returned to fine crystals. The granules of 2-hydroxynaphthalene-3-carboxylic acid produced according to the present invention can be advantageously used as an industrial raw material for producing dyes, pigments, and the like. Example 1 BON before drying obtained by the continuous method described in Japanese Patent Publication No. 56-53296 was centrifugally dehydrated by adjusting the centrifugal force so that the water content was 18%. the
Take 500g in a kneader, add 10g of methanol, knead for 5 minutes, granulate it through a horizontal extrusion type granulator with a hole diameter of 1mm, spread it in a vat and air dry it at 80℃ for 40 minutes to obtain granules with a moisture content of 0.2%. The BON is
410g was obtained. This BON granule did not crumble even after drying, and its scattering properties were significantly suppressed compared to fine powder BON. BON used for granulation
When dried and the particle size was measured, particles smaller than 50μ were found.
It was 73%. The amount of solvent added is ultimately determined by
The amount of water containing 10% by weight of methanol was 24.4 parts by weight based on 100 parts by weight of BON. In order to examine the strength of the BON granules obtained in Example 1 using a tablet friability tester, they were sieved in advance through a 60-mesh Tyler sieve screen, 10g of the granules remaining on the screen was weighed out, and the strength was tested using a tablet friability tester. After 3 minutes, the amount passing through a 60-mesh sieve was measured and determined as the powderization rate. The powdering rate of the BON granules obtained in Example 1 was 6%. Examples 2 to 5, Comparative Examples 1 and 2 When the particle size of the fine powder BON obtained by the solid phase batch method was measured, 81% of the particles were 50 μm or less. Methanol is added to 500g of the finely powdered BON.
BON granules were prepared in the same manner as in Example 1 by adding water containing 20% by weight in the amount shown in Table 1 and kneading for 20 minutes in a kneader. Table 1 shows the state of the mixture when it was passed through the granulator, the state of the granules after drying, and the pulverization rate of the granules. According to the results of the comparative example, when the amount of the mixed solution added was 15 parts by weight to 100 parts by weight of BON, granules did not form, and when 35 parts by weight, the granules adhered to each other after granulation and were quite easy to crumble after drying. It was found that the powdering rate was too high to be of practical use.

[Table] Examples 6 to 10, Comparative Examples 3 and 4 500 g of the finely powdered BON used in Example 2 was mixed with 125 g of water containing methanol at the concentration shown in Table 2.
g was added thereto and kneaded for 20 minutes using a kneader, and then the same procedure as in Example 1 was carried out to prepare granular BON. Table 2 shows the state of the mixture when it was passed through the granulator, the state of the granules after drying, and the pulverization rate. The results of the comparative example show that when the concentration of methanol in the mixed liquid is 3%, the granules are easily crumbled and the pulverization rate is high. It was also observed that when the methanol concentration increased to 30%, the granules became more easily disintegrated.

[Table] Example 11 BON obtained by the continuous method described in Japanese Patent Publication No. 56-53296 was adjusted to a water content of 20% by adjusting the centrifugal force.
It was dehydrated by centrifugation. When we measured the particle size of the dry product of this product, 72% of the particles were 50μ or less.
It contained. This BON with a moisture content of 20% is fed to a continuous kneader at a rate of 100 kg/hour, to which methanol is added at a rate of 3 kg/hour, and after kneading for 3 minutes, it is granulated using a twin-screw horizontal extrusion method with a pore size of 1 mm. The mixture was continuously granulated through a machine (manufactured by Fuji Paudal Co., Ltd., EXD-100). After granulation, it was dried in a fluidized fluid dryer and passed through a sieving machine to continuously obtain BON granules at a rate of 75 kg/hour. The BON granules thus obtained did not crumble even after drying, had significantly reduced scattering properties, and was an easy-to-handle formulation. The amount of the mixed solution of water and methanol added during kneading was 28.8 parts by weight per 100 parts by weight of BON, and the methanol concentration in the mixed solution was 13%. Test Examples 1 to 5 When BON obtained by the continuous method described in Japanese Patent Publication No. 56-53296 was dried and the particle size was measured,
Contained 65% particles smaller than 50μ. After classifying this into particles smaller than 50μ and particles larger than 50μ, they were mixed in varying amounts as shown in Table 3, and 60g of water containing 20% ethanol by weight was added to 200g of this mixture. Granular BON was prepared by kneading, granulating, and drying, and its strength was examined. Table 3 shows the state of the kneaded material when it was passed through the granulator and the pulverization rate of the granules. When the content of crystal particles of 50μ or less was less than 60%, even if it was made into granules, it was easy to crumble, and only granules with a high pulverization rate could be made. Based on the above results, in order to prepare granules, 60
It is known that it is necessary to contain at least %.

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Claims (1)

[Claims] 1 100 crystals of 2-hydroxynaphthalene-3-carboxylic acid containing 60% or more of particles with a particle size of 50μ or less
parts by weight and water containing 5 to 25% by weight of lower alcohol
2-hydroxynaphthalene-3, characterized by granulating and drying a mixture of 18 to 33 parts by weight.
- A method for producing carboxylic acid granules.