Powder of 2,6-naphthalenediol-bis(trimellitate anhydride) and method for producing the same

Abstract

This invention addresses the problem of providing: a 2,6-naphthalenediol-bis(trimellitate anhydride) powder that is easy to handle; and a method for producing the same. This invention solves the problem by providing: a 2,6-naphthalenediol-bis(trimellitate anhydride) powder characterized by having a median diameter within a range from 10 to 100 µm; and a method for producing the same.

Description

[Technical field]

[0001] The present invention relates to a powder of 2,6-naphthalenediol-bis(trimellitate anhydride), which is useful as a raw material for heat-resistant resins such as polyimide resins, a heat-resistant curing agent for epoxy resins, or a resin modifier, and to a method for producing the powder. [Background technology]

[0002] Trimellitic anhydride aryl esters are useful as raw materials for heat-resistant resins such as polyimide resins, and as curing agents or modifiers for epoxy resins and urethane resins. In particular, polyimide resins produced from di(trimellitic anhydride) esters are expected to be used in applications such as flexible printed wiring boards, as they not only have low hygroscopicity and low water absorption, but can also be imparted with properties such as low thermal expansion, heat resistance, and flexibility depending on their structure. Therefore, there is a demand for di(trimellitic anhydride) aryl esters of higher purity and higher quality. 2,6-Naphthalenediol-bis(trimellitate anhydride) is used as a polyimide film suitable for use as a base film for flexible printed circuit boards, a carrier tape for TABs, or a resin for laminates (Patent Document 1). Polyesterimide obtained by polymerizing 2,6-naphthalenediol-bis(trimellitate anhydride) with 4,4'-oxydianiline is used as a hybrid film with organically modified hectorite (Non-Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-285364 A [Non-patent literature]

[0004] [Non-Patent Document 1] Macromolecular Research, 2014, Vol. 22, pp. 549-556 Summary of the Invention [Problem to be solved by the invention]

[0005] The target product of the present invention, 2,6-naphthalenediol-bis(trimellitate anhydride), has poor selectivity and yield in conventional production methods, and has low solubility in various organic solvents, making it difficult to purify by crystallization. Moreover, the product obtained by treatment after the reaction is in the form of fine crystals, which makes it difficult to filter. In addition, when used as a reaction raw material, it has poor fluidity and clogging at the raw material inlet, making it extremely difficult to handle, and is therefore not suitable for industrial production or use as an industrial raw material. The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide a powder of 2,6-naphthalenediol-bis(trimellitate anhydride) that is easy to handle, and a method for producing the same. [Means for solving the problem]

[0006] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that by carrying out crystallization during transesterification, 2,6-naphthalenediol-bis(trimellitate anhydride) having good handleability can be obtained, and have completed the present invention.

[0007] The present invention is as follows. 1. A powder of 2,6-naphthalenediol-bis(trimellitate anhydride) represented by the following chemical formula (1), characterized in that the median diameter is in the range of 10 to 100 μm. [ka] 2. A method for producing a powder of 2,6-naphthalenediol-bis(trimellitate anhydride) according to 1., characterized in that a compound represented by the following general formula (2) is reacted with trimellitic anhydride in the presence of a basic catalyst. [ka] (In the formula, R1 represents an alkyl group having 1 to 6 carbon atoms. Effect of the Invention

[0008] According to the present invention, it is possible to provide a powder of 2,6-naphthalenediol-bis(trimellitate anhydride) represented by the above chemical formula (1), which is suitable for industrial production or use as an industrial raw material and has good handleability, and a method for producing the powder. In addition, the powder of the present invention has improved filterability compared to the conventional powder of 2,6-naphthalenediol-bis(trimellitate anhydride), so that the powder after filtration has a significantly reduced solvent content. In the conventional powder, the powder contained a large amount of solvent even after the filtration operation, so that filtration and removal and transportation of the powder were difficult, and even if the powder was dried to remove the solvent attached thereto, it was difficult to handle and required a large amount of energy and a long time, so that it was not suitable for industrial production. However, the powder of the present invention can be easily and sufficiently filtered, and the time required for filtration can be significantly shortened, the powder after filtration is easy to handle, and the energy and time required for drying the powder can be reduced, so that it is suitable for industrial production and can improve the production efficiency. Furthermore, among the powders of the present invention, those having a median diameter of 30 μm or more have a higher overall fluidity index than conventional powders, and therefore are excellent in fluidity, handling, and operability. As a result, when the powder of the present invention is used as a raw material for resins such as polyimide, adhesion to the raw material inlet of the manufacturing equipment and the associated clogging can be suppressed compared to conventional powders, and manufacturing efficiency can be improved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described in detail below. <About the powder of the present invention> The present invention relates to a powder of 2,6-naphthalenediol-bis(trimellitate anhydride) represented by the following chemical formula (1) having a median diameter in the range of 10 to 100 μm. [ka] The median diameter in the present invention is a value measured using a wet laser diffraction particle size distribution measuring device, and refers to a particle diameter at 50% cumulative value in a volume-based cumulative particle size distribution. The powder of the present invention has a median diameter in the range of 10 to 100 μm, preferably 15 to 90 μm, more preferably 15 to 80 μm, further preferably 30 to 80 μm, and particularly preferably 35 to 80 μm. The powder having a specific median size of the present invention has improved filterability compared to conventional powders, and therefore the powder after filtration has a significantly reduced solvent content, allowing easy and thorough filtration, the filtration time is significantly short, the filtered powder is easy to handle, and the energy and time required for drying the powder can be reduced, making it suitable for industrial production and enabling improved production efficiency. From the viewpoint of obtaining a high molecular weight polyimide, the purity of the 2,6-naphthalenediol-bis(trimellitate anhydride) in the powder of the present invention is preferably 85% or more, more preferably 90% or more, even more preferably 92% or more, and particularly preferably 94% or more.

[0010] The powder of the present invention has an angle of repose (θr) in the range of 25 to 64°, preferably in the range of 31 to 60°, more preferably in the range of 35 to 58°, even more preferably in the range of 35 to 44°, and particularly preferably in the range of 37 to 44°. This prevents the powder of the present invention from adhering to the raw material inlet of a resin manufacturing facility such as polyimide, thereby suppressing clogging. The angle of repose (θr) of the present invention is measured using a multi-tester (MT-1001, manufactured by Seishin Enterprise Co., Ltd.). The powder of the present invention has a spatula angle (θs) in the range of 25 to 75°, preferably in the range of 32 to 72°, more preferably in the range of 40 to 72°, further preferably in the range of 36 to 59°, and particularly preferably in the range of 37 to 59°. Note that the spatula angle (θs) of the present invention is measured using the above-mentioned multi-tester. The powder of the present invention has a compressibility (Cp) in the range of 5 to 37%, preferably in the range of 12 to 36%, more preferably in the range of 13 to 36%, further preferably in the range of 14 to 25%, and particularly preferably in the range of 16 to 25%. The compressibility (Cp) of the present invention means the value calculated by the following formula (a) from the loose bulk density (ρa) and the compacted bulk density (ρp) measured using the above-mentioned multi-tester. Cp(%)=(ρp-ρa) / ρp×100 …(a) The powder of the present invention has a uniformity (Uf) in the range of 1 to 12%, preferably in the range of 1 to 11%, more preferably in the range of 1 to 10%, even more preferably in the range of 1 to 5%, and particularly preferably in the range of 1 to 4%. The uniformity (Uf) of the present invention means a value calculated from the 60% diameter (X60, μm) and 10% diameter (X10, μm) calculated based on the cumulative distribution curve obtained by obtaining the particle size distribution using a robot sifter (sonic vibration type sieving measuring device, RPS-105, manufactured by Seishin Enterprise Co., Ltd.), and the cumulative distribution curve, according to the following formula (b): Uf=X60 / X10 …(b)

[0011] The overall fluidity index in the present invention is generally known as "Carr's index", and its details are described in RL Carr, "Evaluating Flow Properties of Solids", Chem. Eng., 72, 163-8, 1965. More specifically, the overall fluidity index refers to the sum of the indices given individually to the measured values ​​of the angle of repose (θr), compressibility (Cp), spatula angle (θs), and uniformity (Uf) described below. In this way, the overall fluidity index comprehensively evaluates the powder properties based on the angle of repose (θr), compressibility (Cp), spatula angle (θs), and uniformity (Uf). A phenomenon known as "bridging" is problematic when handling powder industrially. Bridging refers to a phenomenon in which powder particles form an arch structure at the discharge port of a powder storage tank, blocking the port and preventing the powder from being discharged. The comprehensive liquidity index is used as an indicator to determine whether or not bridging prevention measures are necessary, as shown in Table 2 below. The powder of the present invention has an overall fluidity index, expressed as the sum of indexes determined from the physical properties of the angle of repose, the spatula angle, the compressibility and the uniformity, in the range of 39.5 to 100, preferably in the range of 44 to 90, more preferably in the range of 44 to 87, even more preferably in the range of 69.5 to 87, and particularly preferably in the range of 70.0 to 83.5. Among the powders of the present invention, a more preferred embodiment, that is, a powder having a median diameter in the range of 30 to 80 μm, is evaluated as being good in terms of the overall fluidity index, and therefore does not require measures to prevent bridging. Furthermore, the powder is excellent in operability, as it solves problems related to powder handling, such as clogging, during industrial production.

[0012] [Table 1]

[0013] [Table 2]

[0014] <Production method of the compound of the present invention represented by chemical formula (1)> The compound of the present invention represented by chemical formula (1) can be produced by subjecting a compound represented by the following general formula (2) and trimellitic anhydride to a transesterification reaction in the presence of a basic catalyst. [ka] (In the formula, R 1 represents an alkyl group having 1 to 6 carbon atoms. R in the above general formula (2) 1 The alkyl group having 1 to 6 carbon atoms is preferably a linear or branched alkyl group having 1 to 4 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, and a t-butyl group. Of these, a methyl group and an ethyl group are preferred, and a methyl group is particularly preferred.

[0015] Examples of the basic catalyst in the production method of the present invention include aliphatic amines (trialkylamines such as trimethylamine and triethylamine, alkanolamines such as triethanolamine and dimethylaminoethanol), alicyclic amines (cyclopentylamine, cyclohexylamine, etc.), aromatic amines (aniline, diethylaniline, etc.), heterocyclic amines (4-dimethylaminopyridine, morpholine, piperidine, etc.), quaternary ammonium salts (tetraalkylammonium halides such as tetraethylammonium chloride and tetraethylammonium bromide, benzyltrialkylammonium halides such as benzyltrimethylammonium chloride, etc.), and metal alkoxides (e.g., potassium t-butoxide, etc.). These basic catalysts can be used alone or in combination of two or more. Among these basic catalysts, heterocyclic amines such as 4-dimethylaminopyridine, tetraalkylammonium halides such as tetraethylammonium bromide, etc. are widely used, and 4-dimethylaminopyridine is particularly preferred from the viewpoints of reaction rate, reaction selectivity, and lowering the reaction temperature. The amount of the basic catalyst used is preferably in the range of 0.01 to 20 mol %, more preferably in the range of 0.02 to 10 mol %, and particularly preferably in the range of 0.1 to 6 mol %, relative to 1 mol of the compound represented by formula (2).

[0016] As an example of the production method of the present invention, R 1 The case where is a methyl group will be described in detail. R in general formula (2) 1 The method for producing 2,6-naphthyl diacetate in which R is a methyl group is not particularly limited, and a conventionally known method, for example, a method using acetic anhydride as in "Reaction I" shown in the following reaction formula, or a method for converting naphthalenediol into acetic acid ester, such as a method of reacting acetic acid or an acetyl halide in the presence of an esterification catalyst such as sulfuric acid or p-toluenesulfonic acid, can be used. Next, as shown in "Reaction II" in the following reaction scheme, 2,6-naphthyl diacetate can be converted to 2,6-naphthalenediol-bis(trimellitate anhydride) by transesterification with trimellitic anhydride. [ka]

[0017] <Reaction I> The amount of acetic anhydride used in "Reaction I" is usually 2 to 4 moles, preferably 2 to 3.5 moles, and more preferably 2 to 3 moles, per mole of 2,6-naphthalenediol. The reaction is preferably carried out using an aromatic hydrocarbon solvent such as toluene, and the amount of the solvent used is preferably in the range of 1 to 10 parts by weight, more preferably in the range of 1 to 6 parts by weight, and even more preferably in the range of 1 to 3 parts by weight, relative to 1 part by weight of 2,6-naphthalenediol. The reaction temperature is preferably in the range of 100 to 130° C., and more preferably in the range of 110 to 120° C. The reaction pressure may be either normal pressure or reduced pressure.

[0018] <Reaction II> In the "Reaction II", the amount of trimellitic anhydride used is usually 2 moles or more, preferably 2 to 10 moles, more preferably 2.1 to 5 moles, even more preferably 2.3 to 4 moles, and particularly preferably 2.6 to 3.4 moles, relative to 1 mole of 2,6-naphthyl diacetate. The temperature of the transesterification reaction of "Reaction II" is usually in the range of 100 to 300°C, preferably in the range of 150 to 250°C, more preferably in the range of 180 to 250°C, and particularly preferably in the range of 200 to 230°C. The reaction pressure may be normal pressure or reduced pressure in order to promote the distillation of the generated acetic acid from the reaction system. When the reaction is carried out under normal pressure, an inert gas may be circulated in the reaction system in order to promote the outflow of the generated carboxylic acid to the outside of the reaction system. When the reaction is carried out under reduced pressure, the reaction pressure can be adjusted, for example, according to the boiling point of the carboxylic acid generated by the transesterification reaction.

[0019] In "Reaction II", it is preferable to use a reaction solvent in the reaction for reasons such as operability during industrial production and improvement of the reaction rate. The solvent to be used is not particularly limited as long as it does not distill out of the reaction vessel at the above reaction temperature and is inactive to the transesterification reaction.Specific examples include aromatic hydrocarbon ether solvents such as alkylaryl ethers such as phenetole and butylphenyl ether, or diaryl ethers such as diphenyl ether and di-p-tolyl ether, aromatic hydrocarbon solvents such as biphenyl and terphenyl, alkyl-substituted naphthalenes such as diisopropyl naphthalene, aliphatic hydrocarbon solvents such as decalin and kerosene, polyalkylene glycol ethers such as tetraethylene glycol dimethyl ether and diethylene glycol dibutyl ether, and organic heat transfer media such as Therm-S series (manufactured by Nippon Steel Chemical Co., Ltd.), KSK-OIL series (manufactured by Soken Chemical Co., Ltd.), or Neo SK-OIL series (manufactured by Soken Chemical Co., Ltd.). When a solvent is used, the amount used is usually in the range of 1 to 10 parts by weight, preferably in the range of 1.5 to 5 parts by weight, and more preferably in the range of 2 to 3 parts by weight, per part by weight of 2,6-naphthyl diacetate. Under such reaction conditions, the reaction is usually completed within the range of 1 to 28 hours, preferably within the range of 1 to 20 hours.

[0020] <Regarding the method for producing the powder of the present invention> A preferred embodiment of the method for producing powder of the present invention will be described below. The powder of the present invention can be obtained by cooling the reaction liquid after the transesterification reaction of the above "Reaction II" to about 30°C at a cooling rate of 40 to 80°C / hour and filtering the reaction liquid. In the present invention, as a factor of the crystal growth of the powder, in Examples 2, 4, and 7 described below, the higher the reaction aging temperature, the larger the crystals obtained, making it clear that the reaction aging temperature is one of the factors necessary for the growth of the particle size. In addition, in Examples 1, 3, 4, and 6, the longer the reaction aging time, the larger the crystals obtained, making it clear that the reaction aging time is also one of the factors for the crystal growth. Note that the reaction aging in the present invention means that the crystals of the powder are grown while the transesterification reaction of "Reaction II" is being carried out. In addition, in Examples 4 and 5, it was found that the cooling rate is also one of the factors in crystal growth, since the slower the cooling rate after the end of "Reaction II", the larger the crystals obtained. From the above, the reaction and ripening temperature, reaction and ripening time, and cooling rate after the reaction are important factors in the crystal growth of the powder in the present invention.

[0021] In the powder production method of the present invention, the reaction and aging temperature and reaction time can be the reaction temperature and reaction time of the above-mentioned "Reaction II", and the preferred ranges are also as described above. The powder of the present invention can be suitably obtained by cooling at a rate of 5° C. / hour or more and 100° C. / hour or less after completion of "Reaction II", preferably 5° C. / hour or more and 80° C. / hour or less, more preferably 10° C. / hour or more and 60° C. / hour or less, and particularly preferably 20° C. / hour or more and 40° C. / hour or less. These factors can be arbitrarily selected within the above-mentioned numerical ranges, taking into consideration the relationship between the median diameter of the resulting powder and the production efficiency in industrial implementation.

[0022] The powder obtained as described above can be isolated by carrying out a step of filtering the powder from the reaction liquid. In order to remove the reaction liquid adhering to the powder, a step of washing the powder with the solvent used in the reaction, acetic acid, or the like may be carried out. The powder of the present invention has excellent handleability because the time until filtration is completed (the liquid is drained) is extremely short in the filtration and washing steps and the solvent content is extremely low, making it very suitable for industrial production and use as an industrial raw material. The isolated powder can be dried to remove the "Reaction II" adhering thereto and the solvent adhering thereto during the filtration and washing steps. The drying step can be carried out under normal pressure or reduced pressure, but in industrial practice, it is preferable to carry out the drying step under reduced pressure, since the solvent can be removed more efficiently. In addition, it is more preferable to carry out the drying step in an inert gas atmosphere such as nitrogen. The temperature at which the drying step is carried out can be in the range of 50 to 250°C, taking into consideration the boiling point of the solvent to be removed, the pressure at which the drying step is carried out, and the like. The powder of the present invention has a significantly reduced solvent content after the filtration step compared to conventional powders, and therefore requires less energy to remove the adhering solvent, and can be dried in a short time, thereby improving production efficiency. EXAMPLES

[0023] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following examples, physical properties were measured by the following methods. <Analysis method> 1. Median diameter Device 1: Shimadzu SALD-2200 (laser diffraction particle size distribution analyzer) Measurement range: 1000~0.030μm Dispersion solvent: Distilled water + neutral detergent Dispersion method: Ultrasonic dispersion 2. Gel Permeation Chromatography Equipment: Tosoh Corporation high-speed GPC equipment HLC-8320GPC Column: TSKgel guardcolum HXL-L 1 piece, TSKgel G2000HXL x 2, 1 TSKgel G3000HXL, TSKgel G4000HXL 1 bottle Mobile phase solvent: Tetrahydrofuran (THF: Fujifilm Wako Pure Chemical, first-class reagent, contains stabilizer (BHT)) Flow rate: Pump Sam. 1.0ml / min, 1 / 3 of Ref. Sam. Column temperature: constant at 40℃ Detector: RI (composition confirmation) 3. Powder characteristics Device 2: Seishin Enterprise Co., Ltd. Multi-tester MT-1001 type (1) Angle of repose (θr), spatula angle (θs) Using the above-mentioned device 2, the angle of repose (θr) and the angle of spatula (θs) were measured. (2) Compressibility (Cp) Using the above-mentioned device 2, the loose bulk density (ρa) and the compacted bulk density (ρp) were measured, and the compressibility (Cp) was calculated based on these measured values ​​according to the following formula (a). Formula (a): Cp(%)=(ρp-ρa) / ρp×100 (3) Uniformity (Uf) The particle size distribution was measured using the above-mentioned Apparatus 1. The ratio of the cumulative 10% diameter (X10) to the 60% diameter (X60) in the cumulative data obtained from the particle size distribution was calculated according to the following formula (b). Formula (b): Uf=X60 / X10 (4) Overall Liquidity Index The overall fluidity index is generally known as the "Carr index," and is an index table proposed by RL Carr that indicates the fluidity of powders, the details of which are described in "Evaluating Flow Properties of Solids," Chem. Eng., 72, 163-8, 1965. In more detail, the indices listed in Table 1 above were individually assigned to each of the measured values ​​of the angle of repose (θr), compressibility (Cp), spatula angle (θs), and uniformity (Uf), and the overall fluidity index was calculated by adding up these indices. Since the overall fluidity index is a comprehensive assessment of powder properties based on the angle of repose (θr), compressibility (Cp), spatula angle (θs) and uniformity (Uf), 2,6-naphthalenediol-bis(trimellitate anhydride) powder with an overall fluidity index within a specific numerical range is sure to have excellent handleability.

[0024] <Synthesis Example> [ka] In a four-neck flask equipped with a thermometer, a stirrer, and a condenser, 400 g (2.50 mol) of 2,6-naphthalenediol, 765 g (7.50 mol) of acetic anhydride, and 610 g of toluene were charged, and the reaction vessel was replaced with nitrogen, and then the reaction was carried out for 9 hours at 110 to 116 ° C. As a result of analysis by high performance liquid chromatography, the reaction selectivity of 2,6-naphthyl diacetate present in the reaction solution was 98.0%. After the reaction was completed, the mixture was cooled to 25°C while stirring, and the precipitated crystals were filtered. The obtained crystals were dried under reduced pressure to obtain 577 g of the target product (yield: 95%). The purity was 100% by high performance liquid chromatography analysis.

[0025] <Example 1> [ka] 150.6g (0.62 mol) of 2,6-naphthyl diacetate obtained in the synthesis example, 358.3g (1.87 mol) of trimellitic anhydride, 3.1g of 4-dimethylaminopyridine, and 1251.8g of diphenyl ether were charged into a four-neck flask equipped with a thermometer, a stirrer, and a cooling tube, and reaction aging was performed while precipitating crystals at 210 to 220 ° C for 3.5 hours. Thereafter, acetic acid was added during cooling at 40 ° C / hour, and the crystals were filtered at 25 ° C. The obtained crystals were heated to 120 ° C under reduced pressure and dried. A powder of 2,6-naphthalenediol-bis (trimellitate anhydride) with a purity of 99% by gel permeation chromatography analysis was obtained. The median diameter of the obtained powder was 38.9 μm.

[0026] <Example 2> The reaction was carried out in the same manner as in Example 1, except that the reaction and aging was carried out for 4 hours at 200 to 210° C. The median diameter of the obtained powder was 25.9 μm.

[0027] <Example 3> The reaction was carried out in the same manner as in Example 1, except that the reaction and aging was carried out for 2 hours. The median diameter of the obtained powder was 27.8 μm.

[0028] <Example 4> The reaction was carried out in the same manner as in Example 1, except that the reaction and aging was carried out for 4 hours. The median diameter of the obtained powder was 41.8 μm.

[0029] <Example 5> The reaction was carried out in the same manner as in Example 1, except that the reaction and maturation time was changed to 4 hours and the subsequent cooling rate was changed to 80° C. / hour. The median diameter of the obtained powder was 19.7 μm.

[0030] <Example 6> The reaction was carried out in the same manner as in Example 1, except that the reaction and aging was carried out for 6 hours. The median diameter of the obtained powder was 51.9 μm.

[0031] <Example 7> The reaction was carried out in the same manner as in Example 1, except that the reaction and aging was carried out for 4 hours at 220 to 230° C. The median diameter of the obtained powder was 47.8 μm.

[0032] <Example 8> The reaction was carried out in the same manner as in Example 1, except that the reaction and aging was carried out for 16.5 hours. The median diameter of the obtained powder was 72.4 μm.

[0033] <Example 9> The reaction was carried out in the same manner as in Example 1, except that the reaction and aging was carried out at 190 to 200° C. for 6 hours and the subsequent cooling rate was changed to 60° C. / hour. The median diameter of the obtained powder was 21.3 μm.

[0034] <Example 10> The reaction was carried out in the same manner as in Example 1, except that the reaction and aging were carried out for 11 hours at 190 to 200° C. and the subsequent cooling rate was changed to 20° C. / hour. The median diameter of the obtained powder was 29.1 μm.

[0035] The temperatures and times during reactive aging in the above Examples 1 to 10, the subsequent cooling rates, and the median diameters (μm) of the resulting powders are summarized in Table 3 below. [Table 3]

[0036] As shown in Table 3, it was confirmed that by adjusting the reaction ripening temperature, reaction ripening time, and cooling rate after completion of the reaction, crystals having a specific median size according to the present invention and easy to handle can be obtained.

[0037] <Comparative Example 1> In a 3000mL three-neck flask equipped with a dropping funnel and a reflux condenser, 510g (2.4 mol) of trimellitic anhydride chloride and 1000mL of toluene were placed and stirred at about 80°C. A solution of 192.0g (1.2 mol) of 2,6-naphthalenediol in 1200mL of toluene and 240mL of pyridine was added dropwise thereto. After the dropwise addition, the mixture was stirred under reflux for about 2 hours, cooled, and the precipitate was filtered to obtain a white solid. This white solid was washed with 3L of water, and then stirred under reflux for about 2 hours using acetic anhydride, and the precipitated crystals were filtered. The white solid obtained by filtration was recrystallized with DMF to obtain 155g (yield: 25%) of a yellow solid. The median diameter of the obtained powder was 7.0 μm.

[0038] <Comparative Example 2> In a 3000mL three-neck flask equipped with a dropping funnel, 50.0g (0.31 mol) of 2,6-naphthalenediol and 296.3g of tetrahydrofuran were placed and completely dissolved. A solution of 166.6g (0.78 mol) of trimellitic anhydride chloride in 1185.3g of tetrahydrofuran was added dropwise thereto. Then, 163.7g of pyridine was added dropwise. After the dropwise addition was completed, the mixture was stirred at room temperature (25°C) for about 24 hours, and the precipitate was filtered to obtain a white solid. This white solid was washed with acetic anhydride, and the crystals were filtered. 140g (yield: 89%) of a yellow solid was obtained by filtration. The median diameter of the obtained powder was 1.8 μm.

[0039] To confirm the usefulness of the obtained powder, (1) filterability and (2) powder flowability were evaluated. (1) Filterability evaluation <Evaluation method> 10.0 g of acetone was added to 1.0 g of each powder obtained in Examples 1, 8 to 10, and Comparative Examples 1 and 2, and the mixture was stirred at room temperature for 1 hour, filtered (Kiriyama funnel), and the time until the filtration was completed (the liquid was drained) was measured. The weight of the powder containing the solvent at that time was then weighed, and the ratio of the weight of the solvent contained to the weight of the original powder (solvent content ratio (%)) was calculated. In addition, the powder after filtration was observed. If it was easily disintegrated and could be easily removed from the funnel as a solid, the powder handleability after filtration was rated as "good." If the powder after filtration was in a paste form containing a large amount of solvent and could not be easily removed from the funnel, the powder handleability after filtration was rated as "bad." When the same procedure was performed using only 10.0 g of acetone without the powder, it took 5 seconds for the liquid to drain.

[0040] <Evaluation Results> The median diameter (μm), filtration time (seconds), solvent content (%), and powder handleability after filtration for each powder, evaluated by the above method, are summarized in Table 4 below. [Table 4]

[0041] As shown in Table 4, it was revealed that the powders of Examples 1 and 8 to 10, which are specific examples of the present invention, could be filtered in about 2.5 to 12 times shorter time than the powders of Comparative Examples 1 and 2. Furthermore, it was revealed that the powders after filtration contained only about 5 to 25% by weight of solvent, and the solidified powder (cake) was in a state that could be easily loosened and easily removed from the funnel as a solid, which made it easy to handle. The powder of the present invention is suitable for industrial production, and is easy to handle even when dried to remove solvent adhering to the powder, and the amount of energy and time required for drying can be reduced, allowing for efficient production. In contrast, the powders of Comparative Examples 1 and 2, which are not specific examples of the present invention (having a median diameter smaller than 10 μm), took a long time of 180 seconds and 150 seconds to complete filtration, and the powder after filtration was in a paste-like state because it contained a large amount of solvent, 60 to 70% by weight, and could not be easily removed from the funnel. In such a state, when obtaining a large amount of powder, it is difficult to filter, or it is difficult to easily remove or transfer from the filter, and it was revealed that it is unsuitable for industrial production. Furthermore, it was also confirmed that when drying to remove the solvent attached to the powder, the handling is poor, and since the solvent is contained in a large amount, 60 to 70% by weight, a large amount of energy and time are required for drying, resulting in inefficient production. From the above results, it has become clear that the powder of the present invention having a median diameter in the range of 10 to 100 μm can be produced industrially with high efficiency and is extremely useful.

[0042] (2) Powder fluidity evaluation <Evaluation method> The fluidity of each powder obtained in Examples 1, 8 to 10 and Comparative Examples 1 and 2 is summarized in the following Tables 5 and 6. Note that the "fluidity evaluation" in Tables 5 and 6 means an evaluation determined based on the definition of "Carr's index," and the necessity of the bridging prevention measures in the above Table 2 based on this "fluidity evaluation" is also shown. [Table 5]

[0043] [Table 6]

[0044] As shown in Table 5, among the specific examples of the present invention, the powders of Examples 1 and 8, which have a median diameter of 30 μm or more, were rated as "slightly good" in terms of the fluidity index and "unnecessary" for bridging prevention measures. This revealed that these powders have excellent handleability and operability and solve problems related to powder handling, such as clogging, during industrial production. On the other hand, as shown in Table 6, the powders of Comparative Examples 1 and 2 were rated as "slightly poor" in terms of the fluidity index, and were powders for which anti-bridging measures were "necessary." The powders of Examples 9 and 10, which are specific examples of the present invention shown in Table 5, were evaluated in terms of fluidity index to be similar to the powders of Comparative Examples 1 and 2 shown in Table 6. However, it was confirmed that the powders were suitable for industrial production and could be produced efficiently because they could be easily filtered, had a filtration time (seconds) that was about 2.5 to 4 times shorter, had a low solvent content after the filtration operation, and were easy to handle.

[0045] The powder having a specific median size of the present invention has improved filterability compared to conventional powders, so that the powder after filtration has a significantly reduced solvent content, and conventional powders contain a large amount of solvent even after filtration, so filtration and removal and transportation of the powder are difficult, and even if the powder is dried to remove the solvent attached thereto, it is difficult to handle, and requires a lot of energy and a long time, so it is not suitable for industrial production. However, the powder of the present invention can be easily filtered, the time required for filtration can be significantly shortened, the powder after filtration is easy to handle, and the energy and time required for drying the powder can be reduced, so it is suitable for industrial production and can improve production efficiency. Furthermore, among the powders of the present invention, powders having a median diameter of 30 μm or more have a good evaluation based on the fluidity index and do not require measures to prevent bridging, so they have excellent fluidity, handling, and operability, and can improve production efficiency.

Claims

1. A powder of 2,6-naphthalenediol-bis(trimellitate anhydride) represented by the following chemical formula (1), characterized in that the median diameter is in the range of 15 to 100 μm. 【Chemical 1】

2. A method for producing a powder of 2,6-naphthalenediol-bis(trimellitate anhydride) according to claim 1, characterized in that a compound represented by the following general formula (2) is reacted with trimellitic anhydride in the presence of a basic catalyst. [Chemical 2] (wherein R １ represents an alkyl group having 1 to 6 carbon atoms.)

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