Powder of 2,2', 3,3', 5,5',-hexamethyl-biphenyl-4,4'-diol-bis (trimellitate anhydride)

Abstract

The objective of this invention is to provide a processable powder of 2,2',3,3',5,5'-hexamethyl-biphenyl-4,4'-diol-bis(triptamine anhydride) and a method for manufacturing the same. The solution of this invention is to provide a powder of 2,2',3,3',5,5'-hexamethyl-biphenyl-4,4'-diol-bis(triptamine anhydride) with an average particle size of 10 μm to 40 μm.

Description

[Technical Field]

[0001] This invention relates to 2,2',3,3',5,5'-hexamethyl-biphenyl-4,4'-diol-bis(triphenylamine) powder. [Previous Technology]

[0002] Polyimide not only possesses excellent heat resistance, but also exhibits chemical resistance, radiation resistance, electrical insulation, and excellent mechanical properties. Therefore, it is widely used in various electronic devices such as flexible printed circuit (FPC) substrates, TAB (Tape Automated Bonding) substrates, protective films for semiconductor components, and interlayer insulating films for integrated circuits. In addition to these properties, polyimide has gained increasing importance in recent years due to its simple manufacturing process, extremely high film purity, and ease of modification using various available monomers.

[0002] The compound shown in formula (A) below, 2,2',3,3',5,5'-hexamethyl-biphenyl-4,4'-diol-bis(triphenylamine anhydride) (hereinafter also referred to as "compound A"), is a compound that combines a high glass transition temperature, a low coefficient of linear thermal expansion comparable to that of metal foil, extremely low water absorption, high modulus of elasticity, sufficient toughness, and sufficient adhesion to metal foil, and is a useful raw material for polyester imide resin (for example, Patent Documents 1 and 2).

[0002]

[0002] [Previous Technical Documents]

[0002] [Patent Documents]

[0003] Patent Document 1: Japanese Patent Application Publication No. 2014-001394

[0003] Patent Document 2: International Publication No. 2014 / 046180

[0004] Patent documents 1 and 2 describe a powder of compound A, which is obtained by filtering and drying a slurry containing precipitate. However, as described in Comparative Example 1 below, the filtration process of the powder requires a lot of time, and the filtered material is a paste containing a large amount of organic solvent, so it cannot be easily removed from the filtration device and is difficult to transfer. Therefore, in addition to poor processability, the drying process also requires a lot of time and energy, making it unsuitable for industrial manufacturing.

[0005] The present invention was developed against the background described above, and the subject of the present invention is to provide a powder of compound A with good processability and a method for manufacturing the same.

[0006] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that, compared with conventional powders, the filterability of 2,2',3,3',5,5'-hexamethyl-biphenyl-4,4'-diol-bis(triphenylamine) powder with a specific particle size range is improved, and the amount of organic solvent contained in the filtered powder is significantly reduced, thereby completing the present invention.

[0007] The present invention is as follows.

[0007] 1. A 2,2',3,3',5,5'-hexamethyl-biphenyl-4,4'-diol-bis(triphenylamine) powder, which is shown in the following formula (A) and has an average particle size of 10 μm to 40 μm.

[0007]

[0007] 2. The powder as described in 1, wherein the coefficient of variation is from 0.01 to 0.25.

[0007] [Coefficient of Variation]: The value obtained by dividing the standard deviation of the volume-based particle size distribution measured by a wet laser diffraction particle size distribution measuring device by the average particle size of the powder.

[0008] The powder of the present invention makes the filtration process from the slurry containing the powder easier and can significantly shorten the required time. Furthermore, the filtered material has a lower organic solvent content and good processability. In addition, compared to the past, the drying time and energy required can be reduced. Therefore, compound A is suitable for industrial manufacturing and can improve production efficiency. [Simplified Explanation of the Diagram]

[0009] Figure 1 is a graph showing the correlation between the product concentration (wt%) at 50°C and the nucleation time (minutes) in the "Confirmation of the Control Range of Product Concentration" of the embodiment and the "Control Range of Product Concentration" below.

[0009] Figure 2 is a graph showing the correlation between the product concentration (weight %) at 30°C and the nucleation time (minutes) in the "Confirmation of the Control Range of Product Concentration" of the embodiment.

[0009] Figure 3 is a graph showing the correlation between the product concentration (weight %) at 80°C and the nucleation time (minutes) in the "Confirmation of the Control Range of Product Concentration" of the embodiment.

[0009] Figure 4 is a microscope photograph of the powder of the present invention obtained in Example 1 (top: 100x magnification, bottom: 1000x magnification).

[0009] Figure 5 is a microscopic photograph (1000x magnification) of powder samples I, II, and III used in the "Filterability Evaluation of Powder of Compound A" in the examples.

Implementation Method

[0010] The present invention will now be described in detail.

[0010] <Average Particle Size>

[0010] The 2,2',3,3',5,5'-hexamethyl-biphenyl-4,4'-diol-bis(triphenyltrihydric anhydride) powder of the present invention has an average particle size in the range of 10 μm to 40 μm.

[0010] In this invention, the "average particle size" is the average particle size calculated from the particle size distribution of a volume-based particle size distribution, measured using a wet laser diffraction particle size distribution measuring device.

[0010] The average particle size of the powder of the present invention is preferably in the range of 10 μm to 35 μm, more preferably in the range of 10 μm to 30 μm, and even more preferably in the range of 15 μm to 30 μm.

[0011] <Coefficient of Variation>

[0011] The coefficient of variation of the powder of the present invention is preferably in the range of 0.01 to 0.25.

[0011] In this invention, the "coefficient of variation" is the value obtained by dividing the standard deviation of the particle size distribution of the volume reference obtained by measuring the particle size distribution by a wet laser diffraction particle size distribution measuring device by the value of the average particle size of the powder.

[0011] The coefficient of variation of the powder of the present invention is preferably in the range of 0.01 to 0.2, more preferably in the range of 0.01 to 0.15, even more preferably in the range of 0.01 to 0.1, and most preferably in the range of 0.01 to 0.05.

[0012] <Method for manufacturing powder of the present invention>

[0012] (Reaction)

[0012] If compound a, which is a raw material belonging to compound A, is mixed with acetic anhydride, which is both a reaction matrix and a solvent, and a solvent used as needed, the dehydration reaction of compound a can be carried out rapidly, and compound A can be generated. The powder system of the present invention can produce the powder of compound A in the present invention by controlling the concentration of compound A in the liquid phase of the reaction solution (hereinafter referred to as "product concentration") while carrying out the dehydration reaction of compound a.

[0012]

[0013] The compound a shown in formula (a) above, which belongs to the raw material of compound A, is 4-({4-[4-(3,4-dicarboxyphenylcarbonyloxy)-2,3,5-trimethylphenyl]-2,3,6-trimethylphenyl]oxycarbonyl}benzene-1,2-dicarboxylic acid, which can be synthesized by the manufacturing method described in the prior art document (International Publication No. 2020 / 080157).

[0013] In order to manufacture the powder of the present invention, the purity of the raw materials, measured by gel permeation chromatography (GPC) as an area percentage, is not particularly limited, but is preferably 90% or more, more preferably 92% or more, even more preferably 94% or more, and most preferably 95% or more.

[0014] In the method for producing compound A shown in the above reaction formula, a reaction catalyst may not be used, but it is preferable to use a reaction catalyst because the reaction can proceed rapidly when a reaction catalyst is used. The reaction catalyst may be an alkaline catalyst or an acidic catalyst, specifically, pyridine or pyridine hydrochloride may be used. The amount of catalyst used is preferably 0.1% by weight or more relative to the weight of acetic anhydride, which is also the reaction matrix and solvent.

[0014] There are no particular limitations on the mixing method of the reactive catalyst. For example, it can be pre-mixed in the solvent before starting the above-mentioned dehydration reaction, or it can be added during the above-mentioned dehydration reaction and the production of the powder of the present invention. Furthermore, the total amount of reactive catalyst used can be mixed at once or in batches.

[0015] In the method for manufacturing compound A shown in the above reaction formula, the amount of acetic anhydride used as both a reaction matrix and solvent is preferably in the range of 1 to 20 times by weight, more preferably in the range of 1 to 15 times by weight, and even more preferably in the range of 1 to 10 times by weight, relative to the raw material compound a. If the upper limit of the amount of acetic anhydride used exceeds 20 times by weight relative to the raw material compound a, the production efficiency is relatively poor.

[0016] When the powder of the present invention is reacted, the crystals of compound A are first present in the reaction solution. There are no limitations to this method. For example, it can be present by mixing the crystals of compound A before the reaction, or by reacting a portion of compound a, which is a raw material, to increase the concentration of the product and precipitate crystals, thereby making it present in the reaction solution.

[0016] There are no limitations on the mixed crystals. Powders of conventionally known compound A can be used, or powders of the present invention obtained by using powders of conventionally known compound A for the purpose of manufacturing the powders of the present invention can be used. Furthermore, crystals whose coefficient of variation has been adjusted by sieving or the like can also be used. In this case, to manufacture powders of compound A of the present invention with a smaller coefficient of variation, it is preferable to use powders with a smaller coefficient of variation.

[0017] (Control range of product concentration)

[0017] The reaction to generate compound A through the dehydration of compound a is carried out by controlling the concentration of the product within a range where the solubility of compound A relative to the reaction solvent is the lower limit and the supersolubility of compound A relative to the reaction solvent is the upper limit. If the concentration of compound A falls below the lower limit of the above-mentioned control range, a portion of the crystals of compound A contained in the reaction solution will dissolve. Therefore, it is preferable to control the reaction to avoid this state as much as possible. However, even if this state occurs, the concentration of compound A can be controlled within the above-mentioned control range and the reaction can continue, thereby producing the powder of the present invention.

[0017] For example, when only acetic anhydride is used as the reaction solvent, the solubility of compound A is 0.02 wt% at 30°C, 0.05 wt% at 50°C, 0.14 wt% at 75°C, 0.18 wt% at 80°C, and 0.40 wt% at 100°C.

[0017] Supersolubility refers to the concentration of a dissolved solute that, when the concentration is supersaturated, maintains a supersaturated state within a specific temperature and time range according to kinetics until nucleation occurs. Supersolubility is affected by factors such as stirring intensity, impurities, and crystallization rate, so it cannot be precisely defined and is usually determined experimentally.

[0017] The relationship between the concentration of the product calculated from the amount of compound a mixed at the reaction temperature and the time required from the mixing of compound a to nucleation (hereinafter referred to as "nucleation time") can be obtained by experiment, thereby determining the supersolubility of compound A in the present invention relative to the reaction solvent.

[0017] Specific examples illustrate the upper limit of the product concentration controlled for manufacturing the powder of the present invention. For example, at 50°C, using only acetic anhydride as the solvent, the relationship between product concentration and nucleation time was experimentally determined. The nucleation time was 5 minutes when the product concentration was 1.4 wt%, 15 minutes when the product concentration was 0.8 wt%, 35 minutes when the product concentration was 0.5 wt%, and 75 minutes when the product concentration was 0.3 wt%. These values ​​can be represented by a curve (oversolubility curve) showing the correlation between product concentration (wt%) and nucleation time (minutes), and the product concentration is controlled using this curve as the upper limit.

[0017] If the reaction is carried out beyond the upper limit, the compound A generated by the reaction will nucleate, so the resulting powder will become finer and the powder of the present invention cannot be obtained.

[0017] That is, when the reaction solvent is only acetic anhydride and the reaction is carried out at 50°C, the lower limit of the concentration of the product is 0.05% by weight of the solubility at this time, and the upper limit is the supersolubility curve obtained above.

[0018] The solvent is not limited to acetic anhydride; any solvent that will not affect the reaction can be used.

[0018] Solvents that can be used together include, for example: ether solvents such as tetrahydrofuran, ketone solvents such as acetone, aromatic hydrocarbon solvents such as toluene, aliphatic hydrocarbon solvents such as hexane, etc.

[0018] At this time, in a mixed solvent containing a solvent that will not affect the reaction, the solubility and supersolubility of compound A are confirmed, and the concentration of the product is controlled within this range in the manner described above, and the reaction is carried out, thereby producing the powder of compound A of the present invention in the same way. There is no limit to the amount of solvent that will not affect the reaction, but if too much is used, the production efficiency will be poor. Therefore, it is preferably less than 10 times by weight relative to the raw material compound a used.

[0018] When using only acetic anhydride as the reaction solvent, the reaction temperature range is from 10 to 100°C, preferably from 20 to 90°C, and most preferably from 30 to 80°C. When using a solvent that will not affect the reaction, the boiling point of the solvent is considered, and the reaction is carried out within a temperature range that does not cause boiling. The temperature during the reaction affects the control range of the product concentration, specifically the lower limit of solubility and the upper limit of supersolubility. Therefore, this effect is identified in advance, allowing the reaction to be carried out at a fixed temperature or with varying temperatures. Maintaining a fixed temperature is preferred.

[0019] (Methods for controlling the concentration of products)

[0019] The above-mentioned "product concentration" can be controlled by mixing compound a, which belongs to the raw materials, with the reaction solution while confirming the product concentration.

[0019] Methods for confirming the concentration of the product include, for example, sampling the liquid phase of the reaction solution and quantifying the concentration of compound A by gel permeation chromatography or liquid chromatography.

[0019] There are no particular restrictions on the mixing method of compound a, which is a raw material. For example, the method of mixing the solid of compound a with the reaction liquid; or the method of mixing the solution obtained by dispersing or dissolving the solid of compound a, which is a raw material, in acetic anhydride or a solvent that will not have an adverse effect on the reaction with the reaction liquid.

[0019] When manufacturing the powder of the present invention on an industrial scale, the method of controlling the above-mentioned "product concentration" and mixing it with the reaction liquid is, for example, a powder metering device. The method of mixing the dispersion or solution of the mixed compound A can be, for example, using a metering device to mix from a tank of pre-prepared dispersion or solution.

[0019] As shown in Comparative Example 2 below, if the dehydration reaction is carried out without controlling the "product concentration", powder with a smaller average particle size can be obtained.

[0020] (Filter)

[0020] The reaction liquid produced according to the above-described method for producing "product concentration" contains the powder of the present invention, and the powder can be separated by a filtration step. As described in Comparative Example 1 below, the conventional powder system of compound A is a paste containing a large amount of solvent, even if the filtration step takes a long time. In contrast, the powder of the present invention exhibits excellent filterability in this filtration step, allowing filtration to be completed in a shorter time compared to the conventional method, and containing less solvent after filtration, thus demonstrating excellent processability.

[0020] (Dry)

[0020] The drying of the powder of the present invention separated by filtration can be carried out in a temperature environment ranging from 40 to 120°C and under normal pressure or reduced pressure, preferably under reduced pressure.

[0020] Compared with conventional powders, the powder of the present invention has less solvent attached, so the drying time is shorter and can be completed with less energy.

[0020] Furthermore, the above-mentioned reaction, filtration, drying and other steps are preferably carried out in an inert gas environment (e.g., nitrogen, argon).

[0021] (Example)

[0021] The present invention will be specifically described below by way of embodiments, but the present invention is not limited to these embodiments.

[0021] The analytical method in this invention is as follows.

[0021] 1. Determination of average particle size

[0021] Apparatus: SALD-2200 (laser diffraction particle size distribution measuring device) manufactured by Shimadzu Corporation.

[0021] Measurement range: 1000 to 0.030 μm.

[0021] Dispersion solvent: distilled water + neutral detergent.

[0021] Dispersion method: Ultrasonic dispersion.

[0021] 2. Microscopic photographs of powders

[0021] Machine: KEYENCE VHX-1000.

[0021] 3. Method for confirming the concentration of the product.

[0021] The concentration of the products of the reaction solution in the examples was confirmed by the following analytical methods.

[0021] [Analysis Method]

[0021] Apparatus: TOSOH HLC-8320GPC high-speed GPC apparatus.

[0021] Series: 1 TSK gel guardcolum HXL-L, 2 TSK gel G2000HXL, 1 TSK gel G3000HXL, 1 TSK gel G400.

[0021] Flow rate: Pump Sam. 1.0 ml / min, 1 / 3 of Ref. Sam.

[0021] Mobile phase: Tetrahydrofuran.

[0021] Tube temperature: fixed at 40℃.

[0021] Detector: Differential refractometer (RI) The RI detector detects the difference in refractive index between the sample side solution and the reference side solution. The refractive index of the solution is related to the weight concentration of the solution.

[0021] Sample concentration: 0 to 100 mg / 50 ml (tetrahydrofuran solution).

[0021] Injection volume: 100μL.

[0021] Calibration method for compound A: Calculated using a calibration curve prepared by GPC. When determining the concentration of the product of compound A, a portion of the sample solution is rapidly obtained using a syringe heated to the same temperature as the solution to be measured, and quickly passed through a filter heated in the same manner (Econofilter, PTFE, 13 mm, 0.45 μm, manufactured by Agilent Technologies) to remove precipitated compound A and unwanted substances.

[0022] The following describes the powder of compound A obtained by conventional manufacturing methods.

[0022] <Comparative Example 1: Powder of Compound A obtained by the manufacturing method described in Patent Document 2 above>

[0022] The manufacturing method described in "Synthesis Example 1" of the above-mentioned Patent Document 2 was tested on an experimental scale of 8.5 times, and after a "refining" step, powder of compound A was obtained. In the "refining" step, when the powder was filtered by suction filtration using a vacuum pump, no liquid was observed to be discharged after about 1 hour of depressurization, but the filter material on the funnel was a paste containing a large amount of solvent.

[0022] The dried filter material was confirmed to contain 49% by weight of solvent based on the weight change before and after drying.

[0022] The average particle size of the dried powder is 4.8 μm, and the coefficient of variation is 0.08.

[0022] As can be seen from the results of Comparative Example 1, the average particle size of the powder of compound A obtained by conventional manufacturing methods is relatively small at 4.8 μm, the filtration process takes a long time, and the filtered material obviously contains a large amount of organic solvent.

[0023] The method for manufacturing compound a will be described next.

[0023] <Reference Synthesis Example 1>

[0023] 242.5 g of trimellitic anhydride chloride and 714.3 g of tetrahydrofuran (THF) were added to a four-necked flask equipped with a thermometer, stirrer, and cooling tube. The trimellitic anhydride chloride was completely dissolved while cooling. 135.3 g of 2,2',3,3',5,5'-hexamethyl-biphenyl-4,4'-diol, 908.5 g of THF, and 197.8 g of pyridine were added to an Erlenmeyer flask and dissolved at room temperature. The solution was intermittently mixed in the aforementioned four-necked flask, which had been cooled to 0 to 5°C, for 2 hours. Then, stirring was continued for 2 hours, followed by heating to 65°C over 1 hour, with stirring continued for 4 hours.

[0023] After the reaction was completed, the mixture was cooled to 40°C, mixed with 117.6g of distilled water, and stirred continuously for 19 hours. The resulting compound a was separated by centrifugation and filtration, and washed with acetone to obtain 697.2g of compound a containing solvent (THF, acetone) and pyridine hydrochloride. The powder was dried at 70°C for 3 hours under reduced pressure of approximately 1.5kPa to obtain 441.3g of compound a containing 34% by weight of pyridine hydrochloride.

[0024] <Reference Synthesis Example 2>

[0024] 242.7 g of trimellitic anhydride chloride and 714.3 g of THF were added to a four-necked flask equipped with a thermometer, stirrer, and cooling tube. The trimellitic anhydride chloride was completely dissolved while cooling. 135.3 g of 2,2',3,3',5,5'-hexamethyl-biphenyl-4,4'-diol, 909.6 g of THF, and 197.8 g of pyridine were added to an Erlenmeyer flask and dissolved at room temperature. The solution was intermittently mixed in the aforementioned four-necked flask, which had been cooled to 0 to 5°C, for 2 hours. Then, stirring was continued for 2 hours, followed by heating to 65°C over 1 hour, with stirring continued for 4 hours.

[0024] After the reaction was completed, the mixture was cooled to 40°C, mixed with 118.1g of distilled water, and stirred continuously for 14 hours. The resulting compound a was separated by centrifugation and filtration, and washed with acetone. 892.7g of compound a containing 42% by weight of THF, acetone, and water, and 21% by weight of pyridine hydrochloride was obtained.

[0025] <Refer to Synthesis Example 3: Preparation of Compound a by Ring-Opening Reaction of Compound A>

[0025] In a four-necked flask equipped with a thermometer, stirrer, and cooling pipe, 102.2 g of compound A obtained by the same method as in Comparative Example 1, 306.5 g of THF, 153.4 g of water, and 1.1 g of 85% phosphoric acid were added. The mixture was heated to 65°C and stirred continuously for 3 hours. The temperature was then lowered to 60°C, and 0.1 g of seed crystals of compound a obtained in Reference Synthesis Example 1 were mixed in. 300 g of water was added dropwise over 20 minutes, and the temperature was then lowered to 15°C at a rate of 10°C / hour. The slurry was filtered by suction, and the resulting powder was dried under reduced pressure at 80°C and 2 kPa to obtain 73.9 g of compound a.

[0026] <Reference Synthesis Example 4>

[0026] 291.6 g of trimellitic anhydride chloride and 859.1 g of THF were added to a four-necked flask equipped with a thermometer, stirrer, and cooling tube. The trimellitic anhydride chloride was completely dissolved while cooling. 162.7 g (0.602 mol) of 2,2',3,3',5,5'-hexamethyl-biphenyl-4,4'-diol, 1093.3 g of THF, and 238.1 g of pyridine were added to an Erlenmeyer flask and dissolved at room temperature. The solution was intermittently mixed in the four-necked flask cooled to 0 to 5°C for 2 hours. Then, stirring was continued for 2 hours. The solution was then heated to 65°C over 1 hour, with stirring continued for 3.5 hours.

[0026] After the reaction was completed, the mixture was cooled to 25°C, mixed with 118.1g of distilled water, heated to 40°C and stirred continuously for 9 hours. Then, compound a was separated by centrifugation and filtration, and washed with acetone to obtain 875.1g of compound a containing 34% by weight of THF, acetone and water, and 24% by weight of pyridine hydrochloride.

[0027] (Confirm the control range of product concentration)

[0027] (1) Solubility (lower limit of the control range of product concentration)

[0027] Determine the solubility of compound A relative to acetic anhydride at the target temperature.

[0027] The results were 0.02% by weight at 30°C, 0.05% by weight at 50°C, 0.14% by weight at 75°C, 0.18% by weight at 80°C, and 0.40% by weight at 100°C.

[0027] (2) Excess solubility (the upper limit of the control range of product concentration)

[0027] Add 30 g of acetic anhydride to a flask with a stir bar, and heat to the desired temperature (30°C, 50°C, 80°C). Change the weight according to the concentration, and mix 0.45 to 0.09 g of compound a prepared in Reference Synthesis Example 3 above into the flask. At this time, before mixing compound a, pyridine at 37% by weight relative to compound a is mixed with acetic anhydride. While timing with a stopwatch from the time compound a is mixed, observe the concentration of the product of compound A. The time when the solution begins to turn cloudy is taken as the nucleation time. When it is difficult to observe visually, the time when the concentration of the product is analyzed by the above method and a concentration change occurs is taken as the nucleation time. Measure the nucleation time of each product concentration. Plot the product concentration (wt%) against the nucleation time (minutes) and prepare a solubility curve (Figures 1 to 3).

[0027] In Figures 1 to 3, the markers represent measured values, and the solid lines represent predicted over-solubility curves.

[0028] <Example 1>

[0028] 150.0 g of acetic anhydride and 1.0 g of powder of compound A obtained in Comparative Example 1 (average particle size 4.8 μm, coefficient of variation 0.08) were added to a four-necked flask equipped with a thermometer, stirrer, and cooling tube, and the seed crystals were suspended. On the other hand, a mixture of 25.8 g of compound a prepared in Reference Synthesis Example 3 and 8.3 g of pyridine as a reaction catalyst was prepared in advance. The temperature of the suspension in the flask was maintained at 30°C, and the prepared mixture was mixed while stirring. As a mixing method, 0.3 g was mixed at intervals of 30 minutes, and the mixing time intervals were gradually shortened to control the overall product concentration so as not to exceed the supersolubility curve determined by the above method (when the product concentration is less than 0.3% by weight, the prepared mixture is mixed with an amount of compound a that will increase the product concentration by 0.15 to 0.2% by weight, thereby controlling the product concentration without exceeding the supersolubility curve).

[0028] The slurry after the reaction was completed was separated into 29.5g of powder containing solvent by suction filtration and dried, thereby obtaining 23.6g of target compound A powder.

[0028] The weight change before and after drying confirms that the filtered powder contains 20% by weight of solvent.

[0028] The average particle size of the obtained powder is 17.1 μm, and the coefficient of variation is 0.02. Furthermore, the powder appears to be scaly when observed under a microscope.

[0028] Figure 4 shows a microscope photograph of the obtained powder. The upper part is a photograph magnified 100 times, and the lower part is a photograph magnified 1000 times.

[0029] <Example 2>

[0029] 80.0 g of acetic anhydride was added to a four-necked flask equipped with a thermometer, stirrer, and cooling pipe. The liquid temperature in the flask was maintained at 50°C, and 1.2 g of compound a prepared in Reference Synthesis Example 1 was mixed while stirring. After about 1 hour and the crystals of compound A precipitated, 22.4 g of the same compound a was mixed. As a mixing method, 0.4 g was mixed at 15-minute intervals, and the mixing time intervals were gradually shortened to control the overall product concentration so as not to exceed the supersolubility curve determined by the above method (when the product concentration is below 0.3% by weight, mixing an amount of compound a will increase the product concentration by 0.3 to 0.4% by weight, thereby controlling the product concentration without exceeding the supersolubility curve). The temperature was then raised to 90 to 95°C, and after stirring for 2 hours, it was cooled to 30°C.

[0029] After the reaction of mixing the total amount of compound a is completed, 12.0g of powder containing solvent is separated by suction filtration and dried to obtain 11.2g of target compound A powder.

[0029] The weight change before and after drying confirms that the filtered powder contains 7% by weight of solvent.

[0029] The average particle size of the obtained powder is 17.0 μm, and the coefficient of variation is 0.02. Furthermore, the powder appears to be scaly when observed under a microscope.

[0030] <Example 3>

[0030] 1000.8 g of acetic anhydride was added to a four-necked flask equipped with a thermometer, stirrer, and cooling pipe. The liquid temperature in the flask was maintained at 50°C, and 24.0 g of compound a prepared in Reference Synthesis Example 2 was mixed while stirring. After about 1 hour and the crystals of compound A precipitated, 483.0 g of the same compound a was mixed. As a mixing method, 9.4 g was mixed at 15-minute intervals, and the mixing time intervals were gradually shortened to control the overall concentration of the product to not exceed the supersolubility curve determined by the above method (when the product concentration is below 0.3 wt%, mixing an amount of compound a will increase the product concentration by 0.3 to 0.4 wt%, thereby controlling the product concentration without exceeding the supersolubility curve). The temperature was then raised to 90 to 95°C, and after stirring for 2 hours, it was cooled to 30°C.

[0030] After the reaction of mixing the total amount of compound a, 270.0g of powder containing solvent was separated by centrifugation and filtration.

[0030] Take out a portion of the separated powder containing solvent and dry it. The ratio of the weight change before and after drying confirms that the filtered powder contains 40% by weight of solvent.

[0030] The average particle size of the dried powder is 10.8 μm, and the coefficient of variation is 0.03.

[0031] <Example 4>

[0031] 20.1 g of acetic anhydride was added to a four-necked flask equipped with a thermometer, stirrer, and cooling pipe. The temperature inside the flask was maintained at 50°C, and 0.5 g of compound a prepared in Reference Synthesis Example 2 was mixed. After about 1 hour and the crystals of compound A precipitated, 202.2 g of the same compound a and 379.4 g of acetic anhydride were mixed. As a mixing method, compound a was first mixed at 0.1 g intervals every 30 minutes, and the mixing time intervals were gradually shortened and the mixing amount was increased to control the overall product concentration so that it did not exceed the supersolubility curve determined by the above method (when the product concentration is below 0.3% by weight, an amount of compound a is mixed to make the product concentration 0.3 to 0.4% by weight, thereby controlling the product concentration without exceeding the supersolubility curve). On the other hand, at the point when 0.8g of compound a is mixed into 202.2g, 30g of acetic anhydride is first mixed, and then acetic anhydride is mixed in such a way that the ratio of compound a in the flask does not exceed 36% until the total amount of acetic anhydride is 399.5g.

[0031] After the reaction of compound a and acetic anhydride is completed, 71.8g of the powder containing solvent is separated by suction filtration and dried to obtain 61.9g of the target compound A powder.

[0031] The weight change before and after drying confirms that the filtered powder contains 14% by weight of solvent.

[0031] The average particle size of the obtained powder is 20.6 μm, and the coefficient of variation is 0.02.

[0032] <Example 5>

[0032] The powder obtained in Example 4 was used for seeding and further manufactured into powder with a larger average particle size.

[0032] In a four-necked flask equipped with a thermometer, stirrer, and cooling tube, 40.6 g of acetic anhydride, 0.1 g of pyridine, and 0.5 g of the undried powder of compound A prepared in Example 4 were added. The temperature of the suspension in the flask was maintained at 50°C, and 13.3 g of compound a prepared in Reference Synthesis Example 3 was mixed. As a mixing method, 0.2 g was mixed at 10-minute intervals, and the mixing time intervals were gradually shortened to control the overall product concentration so as not to exceed the supersolubility curve determined by the above method (when the product concentration is below 0.3% by weight, mixing will increase the product concentration by 0.3 to 0.4% by weight, thereby controlling the product concentration without exceeding the supersolubility curve). Also, during this mixing, at the time point when 6.7 g of compound a was mixed, 40 g of acetic anhydride as a solvent and 0.10 g of pyridine as a catalyst were mixed.

[0032] After the reaction of mixing the total amount of compound a is completed, 12.9g of powder containing solvent is separated by suction filtration and dried to obtain 12.5g of target compound A powder.

[0032] The weight change before and after drying confirms that the filtered powder contains 3% by weight of solvent.

[0032] The average particle size of the obtained powder is 23.2 μm, and the coefficient of variation is 0.02.

[0033] <Example 6>

[0033] Add 100.5g of acetic anhydride to a four-necked flask equipped with a thermometer, a stirrer, and a cooling tube.

[0033] The liquid temperature in the flask was maintained at 80°C, and 2.1 g of compound a prepared in Reference Synthesis Example 2 was mixed while stirring. After crystallization occurred after about 2 hours, 51.0 g of the same compound a was mixed. As a mixing method, 0.7 g was mixed at intervals of 30 minutes, and the mixing time intervals were gradually shortened to control the overall concentration so as not to exceed the supersolubility curve determined by the above method (when the product concentration is below 0.45% by weight, mixing an amount of compound a will increase the product concentration by 0.1 to 0.2% by weight, thereby controlling the product concentration without exceeding the supersolubility curve). The temperature was then raised to 90 to 95°C, and stirring was continued for 2 hours, followed by cooling to 30°C. The slurry after the reaction was completed was filtered by suction to separate 17.7 g of the powder containing the solvent and dried to obtain 15.6 g of the target compound A powder.

[0033] The weight change before and after drying confirms that the filtered powder contains 12% by weight of solvent.

[0033] The average particle size of the dried powder is 13.1 μm, and the coefficient of variation is 0.04.

[0034] <Comparative Example 2: Manufacturing powder of compound A by a manufacturing method that does not control the "product concentration">

[0034] 872.6 g of compound a and 1967.3 g of acetic anhydride, prepared in Reference Synthesis Example 4, were added to a four-necked flask equipped with a thermometer, stirrer, and cooling pipe. The liquid temperature in the flask was then raised to 100°C and stirred continuously for 2 hours, followed by cooling to 30°C. The slurry after the reaction was completed was centrifuged and filtered for 20 minutes to recover the powder. Although no liquid was observed to be discharged, the filtrate was a paste containing a large amount of solvent.

[0034] A portion of the filter material was taken out and dried. The ratio of the weight change before and after drying confirmed that the filter material contained 61% by weight of solvent.

[0034] The average particle size of the powder in the obtained filter material is 2.1 μm, and the coefficient of variation is 0.23.

[0034] The results of Comparative Example 2 confirm that if the reaction is carried out without controlling the "product concentration" of compound A in the reaction system, a smaller powder with an average particle size of 2.1 μm will be obtained, which is the same as the powder of compound A obtained by conventional manufacturing methods. The filtration process takes time, and the precipitate obtained by filtration contains a large amount of organic solvent.

[0035] <The solvent content ratio of the manufactured compound A in the filtered powder>

[0035] The average particle size (μm) of the powder of compound A in Examples 1 to 6 and Comparative Examples 1 and 2, the solvent content (weight %) of the powder after filtration, and the state of the filtered material after filtration are summarized in Table 1 below.

[0035]

[0036] As shown in Table 1, compared with the powder of Comparative Example 1 obtained by conventional methods and the powder of Comparative Example 2 obtained by methods that do not control the concentration of the product, it can be seen that the solvent content of the powders in Examples 1 to 6 of the present invention is relatively low, and the state of the filtered material after the filtration operation is powder. Therefore, it can be seen that the processability during removal or transfer after the filtration operation is better.

[0036] Since the filtered material after the filtration operation of the powder of the present invention is in the form of powder, it is a property suitable for industrial manufacturing. When drying to remove the solvent attached to the powder, it has better processing performance and can reduce the energy or time of drying, and can be manufactured efficiently.

[0036] In contrast, in Compound A (Comparative Example 1) obtained by conventionally known methods (not specific examples of this invention) and Compound A (Comparative Example 2) obtained by methods that do not control the concentration of the product, it is known that the filter material is a paste containing a large amount of solvent, making it significantly more difficult to handle when removing or transferring it after filtration. Under such conditions, it is difficult to filter the powder in the industrial manufacturing of Compound A, or it is not easy to remove it from the filter, and it is also difficult to transfer, so it is considered unsuitable for industrial manufacturing. Furthermore, when drying to remove the solvent adhering to the powder, it is known that the processability is poor and it contains a large amount of solvent, so drying requires a large amount of energy or time, which is considered less efficient in manufacturing.

[0036] As can be seen from the above results, the powder of the present invention can be effectively manufactured in industry and is highly usable.

[0037] <Evaluation of the filterability of powder of compound A>

[0037] To verify the causal relationship between the average particle size of compound A and its filterability, the filterability was evaluated in the following manner.

[0037] (Evaluation Method)

[0037] The filterability of powder samples I (powder of Example 1), II, and III (powders with different average particle sizes obtained by the same method as Comparative Example 1) of compound A with the average particle size shown in Table 2 below was evaluated by the following machine and operation to the required filtration time ("filtration time").

[0037] (Device)

[0037] Prepare a filtration device equipped with a pressure reducing device (water flow air pump), a pressure regulating valve and a pressure gauge (PG-100 HANDY MANOMETER manufactured by COPAL ELECTRONICS) and filtered by a Kiriyama funnel (filter paper No. 5C).

[0037] (Operation)

[0037] Mix 10g of powder and 34g of acetic anhydride in a beaker to prepare a slurry.

[0037] First, while reducing the pressure using a water-cooled air pump, the prepared slurry is fed into the Kiriyama funnel of the device to form a filter material of uniform thickness, and the filtrate is recovered. Then, the recovered filtrate is quickly injected into the filter material on the Kiriyama funnel, and the pressure inside the filtration device is controlled at 10 kPa for filtration.

[0037] (Filtering Time)

[0037] The time (in seconds) from when the total amount of filtrate is injected onto the filter material until the filtrate is drawn out and the pressure begins to rise is temporarily reduced by suction, and this time is taken as the "filtration time".

[0037] The physical properties and filtration times (seconds) of the above powder samples I, II and III are summarized in Table 2 below.

[0037] Furthermore, Figure 5 shows microscope photographs (1000x magnification) of powder samples I, II, and III.

[0038] [Table 2]

[0039] Compared with Sample II or Sample III, which are different from the powder of the present invention and belong to the previously known powder, it can be seen that Sample I of Example 1 of the present invention can shorten the filtration time by about 2.7 to about 7.2 times.

[0039] Furthermore, compared to the powders of Comparative Examples 1 and 2, the amount of solvent contained in the powders of Examples 1 to 3 of the present invention is significantly reduced after the filtration operation. Therefore, it was confirmed in the subsequent drying step that the powder can be dried in a short time, which can significantly reduce the energy required for solvent evaporation.

[0039] Therefore, the powder of the present invention can be effectively implemented in industrial production, and is therefore highly usable.

Claims

1. A powder of 2,2',3,3',5,5'-hexamethyl-biphenyl-4,4'-diol-bis(triphenylamine), which is as shown in formula (A) below, and has an average particle size of 10 μm to 40 μm, and a coefficient of variation of 0.01 to 0.1, [coefficient of variation]: the value obtained by dividing the standard deviation of the volume-based particle size distribution measured by a wet laser diffraction particle size distribution measuring device by the value of the average particle size of the powder.

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