Process for producing polycyanoaryl ether powder

Abstract: A process for producing a polycyanoaryl ether powder which comprises reacting dihalogenobenzonitrile, dihydric phenol and alkali metal salt in the presence of a polymerization solvent, and distilling the solvent while applying shearing force to the reaction mixture is disclosed. According to the process, a polycyanoaryl ether powder which is excellent in physical properties and useful as the materials for electronic appliances, electric appliances, and parts of machines can be produced efficiently.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing polycyanoaryl ether powder. More particularly, it is concerned with a process for the efficient production of a polycyanoaryl ether powder which is useful as a material for electronic appliances, electric appliances, and parts of various machines. 2. Description of Related Arts Heretofore, polycyanoaryl ether produced from dichlorobenzonitrile and dihydric phenol has been known as high performance engineering plastics (see Japanese Patent Application Laid-Open No. 223226/1987). In order to increase the molecular weight of said polycyanoaryl ether, a process for adding difluorobenzonitrile was proposed (Japanese Patent Application Laid-Open No. 189435/1988). Polycyanoaryl ether produced from dihalogenobenzonitrile and dihydric phenol according to these processes is crystalline polymer, so it is solidified by cooling after the completion of polymerization. In order to put said polymer into practical use, however, it is required to remove the solvents, inorganic salts, oligomer and the like. Their removal requires washing with solvents having low boiling points or water. For example, Japanese patent Application Laid-Open No. 212430/1987 discloses a method of purifying the above-mentioned polymer by treating with a specified solvent. For washing with solvent, however, a grinding step to mechanically grind the solidified polymer to fine powder is required, and said grinding step has defects that a large energy is required and that it is difficult to obtain a sufficient purification-effect owing to the relatively large particle size of the polymer. Under such circumstances, the present inventor's group developed a process wherein solvents such as methanol, ethanol, methyl ethyl ketone, acetone, or water are used as so-called pulverization solvents after dihalogenobenzonitrile and dihydric phenol are polycondensed (JP-A-1 135 833). According to said process, fine particles can be obtained easily without a step to mechanically grind the resultant polymer, but in some cases, filtration ability after the pulverization is poor. And in other cases, solidifying phenomena occurs at the pulverization, which makes the polymer treatment inconvenient, and makes the filtration and washing as the subsequent steps difficult. Further, if water is used solely as a pulverization solvent, solidification occurs locally which makes filtration and washing as the subsequent steps very difficult. Polymers particulated by adding pulverization solvent and ground by cooling to setting are small in bulk density and have a large volume of cake in washing, so the operation ability in washing step and granulating step is problematic. In addition, liquid content in washing is so high that it took a long time to remove the impurities and purity the product. Further, a method of using N-methylpyrrolidone as pulverization solvent has been studied, but, the powder obtained by pulverization step with a mixed solvent of N-methylpyrrolidone and water has difficulties in handling because of a large volume of cake in the washing step, and is low in bulk density. In the pulverization step with the use of above-mentioned pulverization solvent, inconveniently a large amount of solvent must be used so as to prevent caking or adhering. Because of a small bulk density, flow rate becomes unstable at the molding. On the other hand, if solvent is distilled away without depositing the polymer, during or after the polymerization, flooding will occur, and caking and adhering are caused. In this case, there are defects that the handling and washability become worse, and that bulk density is low. In this situation, the present inventors repeated intensive studies to develop a process to dissolve above-mentioned technical defects, and to obtain a polymer having a small liquid content and a good washability, with a small volume of cake in the washing step of the polymer obtained after the polycondensation of dihalogenobenzonitrile and dihydric phenol, and to produce stably and easily a polycyanoaryl ether powder which is high in the bulky density and is excellent in the moldability. As the result, it was found that the above object can be attained by distilling away the solvent with a particular step after polycondensation reaction. The present invention was accomplished on the basis of such a knowledge. SUMMARY OF THE INVENTION The present invention provides a process for producing polycyanoaryl ether powder as defined in claim 1. DESCRIPTION OF PREFERRED EMBODIMENTS The dihalogenobenzonitrile to be used in the present invention includes 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile, 2,4-dichlorobenzonitrile, 2,4-difluorobenzonitrile, 2-chloro-6-fluorobenzonitrile, 2-fluoro-6-chlorobenzonitrile, and among them, 2,6-dichlorobenzonitrile, and 2,6-difluorobenzonitrile are particularly preferred. Dihydric phenols include dihydroxybenzenes such as 1,2-dihydroxybenzene, 1,3-dihydroxybenzene, 1 ,4-dihydroxybenzene, 2-methyl-1,4-dihydroxybenzene, 2,6-dimethyl-1,4-dihydroxybenzene, and 2-methoxy-1,4-dihydroxybenzene; dihydroxybiphenyls such as 4,4'-dihydroxybiphenyl, 3,5'-dihydroxybiphenyl, 3,5-dihydroxybiphenyl, 3-methyl-4,4'-dihydroxybiphenyl, and 2,2'-dimethyl-4,4'-dihydroxyphenyl; dihydroxynaphthalenes such as 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1,8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, and 4,8-dimethyl-2,6-dihydroxynaphthalene; and dihydroxydiphenylethers such as 4,4'-dihydroxydiphenylether. The particularly preferred dihydroxyaryl compounds are 1,3- and 1,4-dihydroxybenzene (resorcinol, hydroquinone). Further, examples of alkali metal salts are inorganic bases such as sodium hydrocarbonate, sodium carbonate, potassium carbonate, and potassium hydrocarbonate, among which sodium hydrocarbonate, sodium carbonate, and potassium carbonate are particularly preferred. In the process of the present invention, dihalogenobenzonitrile, dihydric phenol and alkali metal salt as mentioned above are mixed in an appropriate ratio, dihalogenobenzonitrile and dihydric phenol are mixed in an almost equal molar ratio, and alkali metal salt, to dihalogenobenzonitrile as the starting material is used in a molar ratio of 1.0 - 3.0 to 1, and specifically sodium hydrocarbonate is in a molar ratio of 2.05 - 2.40 to 1 and sodium carbonate and potassium carbonate are used in a molar ratio of 1.03 - 1.30 to 1. As the solvent to be used in the polymerization (polycondensation), that is, as polymerization solvent, N-alkylcarboxylic acid amides such as N-methylformamide, and ethylacetoamide; N,N-dialkylcarboxylic acid amides such as N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethyl acetoamide; N-alkyllactams such as N-methylpyrrolidone, and N-ethylpyrrolidone; N-alkylcarboxyimide such as N-methylpyrrolydinone; sulfoxides such as dimethylsulfoxide, and diethylsulfoxide; sulfones such as dimethylsulfone, diethylsulfone, and diphenylsulfone; cyclosulfones such as sulfolane; nitriles such as acetonitrile, propionic nitrile, butylonitrile, succinonitrile, and benzonitrile; benzophenone, and mixtures thereof. Among these solvents, aprotic strong polar organic solvents such as dimethylsulfoxide, dimethylsulfone, diethylsulfone, diphenylsulfone, sulfolane, N,N-dimethylformamide, N-methylpyrrolidone, N-methylpyrrolidone, and mixtures thereof are preferable, and among them, particularly preferable ones are sulfolane, N-methylpyrrolidone, and N-methyl-2-pyrrolidone (NMP). In the polymerization, it is preferred that the above-mentioned dihalogenobenzonitrile and dihydric phenol as the starting material are dissolved in the above-mentioned solvent. For instance, when resorcinol is used as dihydric phenol and N-methylpyrrolidone is used as polymerization solution, preferred concentration of the solution is 0.5 to 2.5 (mol of resorcinol/liter of N-methylpyrrolidone), more preferably 0.7 to 1.5 (mol of resorcinol/liter of N-methylpyrrolidone). Said polycondensation reaction is carried out in a temperature range of 140 to 350°C, preferably 160 to 250°C for 1 to 10 hours, preferably 2 to 5 hours. Further, said reaction may be carried out under ordinary pressure or under some pressure. The reaction will be more effective in an atmosphere of inert gas such as argon gas, and nitrogen gas. In the above-mentioned polymerization condensation reaction, molecular weight modifier can be added, if required. As the molecular weight modifiers to be used, monohalogenobenzonitrile, dihalogenobenzonitrile and the like are mentioned. The amount to be used can be determined properly depending on the molecular weight of the desired polymer. Further, specific conditions of the above-mentioned conditions are described in Japanese Patent Application Laid-Open Nos. 206433/1984, 162523/1986, 192732/1986, 223226/1987, 189435/1988, and 270733/1988. In the process of the present invention, after the completion of the above-mentioned polycondensation reaction, any one of the three alternatives (i) to (iii) is carried out. In the alternative (i) it is preferred to distill the solvent away while applying a shearing force to and cooling the reaction mixture. In the alternative (ii) it is preferred to dilute the reaction mixture by adding the polymerization solvent in such an amount that the resultant polymer may not be pulverized, and subsequently, to pulverize the resultant polymer by adding a pulverization solvent of the resultant polymer, and then distill the solvent away. By removing the solvent in this manner, a polymer having an excellent washability with a small liquid content can be obtained. As apparatus to apply shearing force (pulverization apparatus) to the reaction mixture (slurry) in (i) above, tank-type reactor provided with agitating blades in the tank, such as ordinary anchor blade, seepback blade, paddle, leaf blade, and sigma-type blade, mono- or multi-axial kneader or extruder, oscillating apparatus, and paddle drier can be used. Said pulverization apparatus may be incorporated in the reactor, for example, formed by providing agitating blades to the reactor, or pulverization tank or pulverization appliance may be provided separately from the reactor. The temperature of the slurry ranges from the room temperature to the boiling point (according to the atmospheric pressure), under the ordinary pressure with the use of various inert gases, azeotropic solvent as distillation medium, or self pressure, or under reduced pressure. The period of distillation of the solvent is adjusted so that the solvent of 0.007 to 0.7 times, preferably 0.3 to 0.97 as much as the solvent to be used for the reaction may be distilled away in a minute. As described in the preferred embodiment of (i) above, the volume of the cake can be reduced by cooling the reaction mixture while applying a shearing force, and then by distilling away the solvent. The temperature for the cooling is preferably lower than the polymerization temperature, for instance, a temperature ranging from the room temperature to about 195°C, and can be effected successively to whole or a part of the period of distillation of the solvent or at proper intervals, but usually cooling for 0 (corresponding to (i) above) to 480 minutes will be enough. In (ii) above, a solvent (pulverization solvent) which has a compatibility with polymerization solvent but does not dissolve the resultant polymer is added. When such a solvent is added thereto, the resultant polymer is not dissolved but fractionated into particles. As shown in the preferred embodiment of (ii) above, after a diluent is added to the polymerization solvent with subsequent cooling, a pulverization solvent can be added. As the diluent, a neutral polar solvent similar to the above-described polymerization solvent can be used. The amount of the diluent to be added is 1 cc or more per 1 g of the resultant polymer, or within three times (ratio by volume) as large as that of the polymerization solvent. The diluent may be added all at once or by degrees over within 30 minutes. It is preferred that the temperature of the reaction system at the dilution ranges from 150°C to the polymerization temperature, and the temperature of the system after dilution ranges from 50 to 190°C. On the other hand, examples of the pulverization solvent are methanol, ethanol, propanol, isopropanol, acetone, methyl ethyl ketone, water, and mixtures thereof, and the mixtures of a polymerization solvent. Among them, those with low boiling point is preferable so as not to leave the solvent in the polymer. The amount of pulverization solvent to be added depends on various conditions, and cannot be determined unconditionally, but usually at least 0.2 times, preferably 0.5 to 5.0 times as much as the polymer solution. If the amount to be added is too small, only a part of the polymer may be pulverized, and other parts may become cake state, which leads to a low yield. In adding the pulverization solvent, the temperature of the polymer solution can be set in a proper range, but, generally, in a range lower than the boiling point of the mixture of polymer solution and pulverization solvent, preferably in a range of 100 to 180°C. If it is too low, the polymer becomes cake before the addition of said solvent, and if it is too high, the amount of evaporated pulverization solvent is undesirably high. Above-mentioned pulverization solvent can be added all at once, but usually added over 1 to 60 minutes, preferably 3 to 20 minutes. If the solvent is added too rapidly, the polymer might partly aggregate without being pulverized, while if addition takes too much time, the productivity is lowered. As the above-described pulverization solvent, a solvent mixed with the polymerization solvent, for example, a mixed solvent of the above-mentioned N-methylpyrrolidone and water can be used. The ratio of N-methylpyrrolidone and water in the above mixed solvent is not particularly limited, but usually, is N-methylpyrrolidone/water = 95/5 to 30/70 (ratio by volume), preferably 90/10 to 50/50 (ratio by volume). In usual, the amount of the pulverization solvent comprising N-methylpyrrolidone and water is 0.5 to 5 times (ratio by volume) of that of the above-mentioned polymerization solvent. After the resultant polymer is pulverized in this way, the solvent is distilled away under the same conditions as above. As described in (iii) above, the reaction mixture is cooled as it is after the completion of the reaction to deposit the resultant polymer, and the deposited polymer may be pulverized. As the conditions for cooling, the reaction mixture is preferably cooled in a range of from the room temperature to 130°C over 1 to 480 minutes, and the application of a shearing force at cooling brings a deposition under a more preferable condition. Pulverization can be carried out by the usually mechanical grinding means, at the room temperature to the boiling point of the solvent. When polymerization solvent or pulverization solvent is added in the amount of 1 cc or more per 1 g of resultant polymer at said pulverization, the pulverization of the polymer can be carried out easily. The removal of the solvent after the pulverization can be effected as above. When the polymer particles obtained are filtrated, and subjected to necessary post-treatment such as washing, and drying, the desired polymer powder can be obtained. As the solvent for washing, polymerization solvent or pulverization solvent can be used. The preferable amount of the washing solvent to be used is usually 0 (no washing) to 10 times that of the polymerization solvent, and when the mixed solvent with the polymerization solvent is used, the ratio is as polymerization solvent/pulverization solvent = 100/0 to 0/100. The appropriate temperature of washing solution ranges from the room temperature to the boiling point, the appropriate washing period ranges from 1 to 60 minutes, and the washing time is 0 (no washing) to 10 times. By the washing, the remaining oligomer and others in the polymer cake are removed effectively. The remaining alkali can be removed by neutralizing with inorganic acids such as hydrochloric acid and organic acid such as oxalic acid, and further the remaining salt can be removed by washing with water at the room temperature to 150°C. Then by a proper drying treatment, a polycyanoarylether powder favorable in molecular weight, powder properties, thermal properties, amount of impurities can be obtained. As described above, according to the present invention, a polymer cake having a small cake volume in washing, and being excellent in washing ability with liquid content can be obtained, and further, a polycyanoarylether powder favorable in molecular weight, powder properties, thermal properties, and amount of impurities can be obtained easily. Consequently, subsequent purifying process can be carried out effectively, and a polycyanoarylether powder of high quality having a very small amount of impurities can be obtained easily. Therefore, the polycyanoarylether powder obtained according to the present invention is expected for an advantageous utilization as the material for electronic appliances, electric appliances, and parts of machines. The present invention will be described in detail with the following examples and comparative examples. Example 1 16.5 g of resorcinol, 25.7 g of 2,6-dichlorobenzonitrile, 17.5 g of sodium carbonate, and 150 ml of N-methyl-2-pyrrolidone (NMP) were placed in a 1-liter separable flask equipped with a rectifier, an agitater, a Dean-stark trap, and an inert gas blow inlet. The mixture was then heated to 195°C while blowing argon gas, and one hour later, toluene was added thereto, refluxed, dehydrated, then reacted at 200°C for 75 minutes. Subsequently, a solution of 0.3 g of 2,6-difluorobenzonitrile/ 5 ml of NMP was added and the mixture was reacted for 75 minutes to increase the molecular weight, and then a solution of 1.0 g of 2,6-difluorobenzonitrile/ 5 ml of NMP was added, reacted for 30 minutes to effect a terminal treatment. As the agitater therein, an anchor blade was used, with a clearance of 13 mm between the blade and the wall of the reactor. After the reaction was completed, the solution was mixed for 10 minutes at 200 rpm. The temperature of the polymer solution was 191°C, wherein a part of the content was deposited. Immediately in this condition, NMP was vacuum-distilled away, while shearing force was applied at 500 rpm. The rate of distillation was 116 ml per 3 minutes. By this operation, powdery particles were obtained. Then 150 ml of NMP was added thereto, and the mixture was stirred and washed at 110°C for 10 minutes, and the oligomer was filtrated off. Then 400 ml of water was added thereto, and the mixture was stirred and washed for 30 minutes at 60 to 80°C, filtrated to remove the remaining salt component. The residue was rinsed with water five times, and at the third rinsing, 2.5 g of oxalic dihydrate was added thereto. After drying under reduced pressure for 8 hours at 130°C, a polymer was obtained. At each washing step, the liquid content as well as the volume of the cake was measured. As the result, the volume of the cake was 4.3 cc/g (weight as dry polymer). The liquid content after washing with NMP was 50% by weight and that after washing with water was 56% by weight. The liquid content was measured at each washing step, by calculating the amount of evaporated solvent of the sampled polymer cake when the polymer cake attained equilibrium weight after dried under reduced pressure at 140°C. The amount of the resultant polymer was 30.01 g (yield: 95.7% by weight), and reduced viscosity was 1.34 dl/g (60°C, in p-chlorophenol solvent, concentration : 0.2 g/dl). The remaining Na in the polymer was 5 ppm, residual oligomer in the polymer was 1.3% by weight, residual NMP in the polymer was 0.01% by weight, volume density of the polymer was 0.33 g/cc, and the average particle size was 150 micron. The average particle size was measured by sieving the dried powder and weighing it. The methods used for measuring the residual components are as follows: Na, K : Atomic absorption analysis Oligomer : High performance liquid chromatography (dimethylformamide extraction) NMP : Gas chromatography (chloroform extraction) Examples 2 to 14 The procedure of Example 1 was repeated substituting the reaction conditions for those shown in Table 1 to obtain a polymer powder, and for each example, liquid content, residual Na, residual oligomer, residual NMP, reduced viscosity, volume of the cake, volume density, and average particle size were measured in the same manner as in Example 1. The results are shown in Table 1. In Example 4, the reaction mixture was slowly cooled while stirred slowly after polymerization condensation, and temperature was lowered (from 200°C to 30°C in 5 hours) to obtain a slurry. The bath temperature was set at 50°C, and NMP was vacuum distilled away while slowly mixing. In Example 7, the terminal treatment was carried out immediately, without adding 2,6-difluorobenzonitrile to increase molecular weight. In Example 8, the terminal treatment was carried out after adding 2,6-difluorobenzonitrile to increase molecular weight and reacting for 165 minutes. In Examples 9 to 12, the shape of the agitating blade was altered. In Example 13, the amount of the starting material used was increased to 1.33 times, the mixture after the reaction was transferred to a kneader preheated to about 200°C, and the solvent was distilled away while mixing. In Example 14, the starting material used was doubled, the mixture was transferred to a kneader preheated to about 200°C, slowly cooled to about room temperature (for about 4 hours), to deposit particles, and then the kneader was heated again to about 200°C to distill away the solvent. The kneader used in Examples 13 and 14 was a biaxial type with a mixing part of approximately 120 mm in total length, and with the distance between the blades being about 5 to 20 mm. Example 15 Polymerization reaction was carried out using the same apparatus and procedure as in Example 1. Then the bath temperature was set at 225°C, and the contents were mixed while applying a shearing force with blades rotating at 500 rpm. Argon gas was blown at the rate of 300 ml/min into the polymer solution, to distill away NMP. The temperature of the contents at this time was 204 to 198°C. The distillation rate of NMP was 95 ml per 16 minutes. By this operation, powdery particles were obtained. Next, the powder was subjected to NMP washing, neutralizing and washing in the same manner as in Example 1, and then dried. The liquid content, residual Na, residual oligomer, residual NMP, reduced viscosity, cake volume, volume density and average particle size of polymer cake were measured in the same manner as in Example 1. The results are shown in Table 1. Example 16 With the use of the same apparatus as in Example 1, polycondensation was performed using dihydric phenol and 1,4-dihydroxybenzene(hydroquinone). 16.5 g of hydroquinone, 26.3 g of 2,6-dichlorobenzonitrile, 24.9 g of potassium carbonate and 150 ml of NMP were placed in the reactor, heated to 150°C while blowing argon gas, and maintained at 150°C for 2 hours. Then, the mixture was heated to 195°C, refluxed with toluene for one hour to be dehydrated. Then, the mixture was reacted for 2 hours at 200°C. After the reaction was completed, the reaction product was cooled to an inner temperature of 170°C while mixed at 200 rpm. At this time, a part of the reaction mixture was deposited. In this condition, NMP was distilled away immediately, while applying a shearing force at 500 rpm. The rate of NMP distillation was 110 ml per 4 minutes. By this operation, powdery particles were obtained. Subsequently, 400 ml of water was added thereto, and a salt component was removed and dried in the same manner as in Example 1. The ratio of liquid content, residual K, residual NMP, reduced viscosity, cake volume, volume density, and average particle size of the polymer cake were measured in the same manner as in Example 1. The results are shown in Table 1. Example 17 The polymerization procedure of Example 1 was repeated except that each twice amount of the starting material and the solvent were used, and 100 ml of NMP was added thereto to dilute the reaction solution. The temperature of the content in this case was 173°C. Subsequently, 300 ml of mixed solvent of NMP and water (in the ratio of 8 : 2 by volume) was added to obtain a slurry. The temperature of the content was 112°C. The slurry thus obtained was kept at 110 to 130°C, and water and NMP were vacuum-distilled away over 60 minutes. The amount of the solvent distilled away then was 620 ml. Then, the residue was washed with NMP (300 ml, 110°C, 10 minutes) and filtrated in the same manner as in Example 1, and thus oligomer was washed away. Next, the reaction product was neutralized and washed with water (800 ml, 60 to 80°C, 30 minutes) and the residual salt was removed. At this washing step, washing and filtration were repeated five times. At the third washing, 5 g of oxalic dihydrate was added thereto. The mixture was dried at 130°C for 8 hours to obtain a polymer. In the same manner as in Example 1, liquid content, residual Na, residual oligomer, residual NMP, reduced viscosity, cake volume, volume density, and average particle size of the resultant polymer cake were determined. The results are shown in Table 2. Example 18 The polymerization as shown in Example 1 was conducted, and then the resultant polymer was transferred to a bat, and cooled to room temperature and solidified. The temperature one minute after the start of cooling was 100°C, and the temperature after 15 minutes was 30°C. Next, after the polymer was finely ground with spatula, heated to 130°C, and NMP was distilled away over 11 minutes. The amount of the solvent distilled away then was 112 ml. Subsequently, the residue was subjected to NMP washing, neutralization and washing. The liquid content, residual Na, residual oligomer, residual NMP, reduced viscosity, cake volume, volume density, and average particle size of the resultant polymer cake were measured. The results are shown in Table 2. Example 19 Polymerization procedure was conducted in the same manner as in Example 1, and the reaction product was transferred to the bat, and cooled to room temperature and solidified. The temperature one minute after the start of cooling was 120°C, and the temperature after 18 minutes was 30°C. Then, the polymer was ground with a blender using 300 ml of a mixed solvent of NMP and water (in a ratio of 8 : 2 by volume), and then the slurry was heated to 130°C, and NMP and water was distilled away over 65 minutes. The amount of the solvent distilled away then was 411 ml. Subsequently, the residue was subjected to NMP washing, neutralizing and washing in the same manner as in Example 1. The resultant polymer cake was measured for liquid content residual Na, residual oligomer, residual NMP, reduced viscosity, cake volume, volume density, and average particle size, in the same manner as in Example 1. The results are shown in Table 2. Comparative Example 1 Polymerization condensation was conducted in the same manner as in Example 1, and immediately on completion of the reaction, NMP was vacuum-distilled away without applying any shearing force. After several seconds in that conditions, the content was bumped, wherein it was solidified on and adhered to the reactor or blades. The distillation ratio at that point was 66 ml per three minutes. From that conditions, grinding and peeling was effected by spatula and the like, but the polymers formed cake or film, and powder-like particles were not obtained. Comparative Example 2 Polymerization condensation was conducted in the same manner as in Example 1, and the content was transferred to the kneader used in Examples 13 and 14 to be mixed at room temperature, cooled to room temperature while mixing the content, wherein a polymer cake was obtained. Then, the content was taken out, 400 ml of a mixed solvent of NMP and water (in a ratio of 8 : 2 by volume) was added thereto, and mixed and washed at 110°C for 10 minutes, and filtrated to remove the residual oligomer. Subsequently, the residue was washed with 400 ml of water at 60 to 80°C for 30 minutes, and filtrated to remove the residual salt. This washing step was repeated five times. At the third washing, 2.5 g of oxalic dihydrate was added thereto. Thereafter, the mixture was vacuum-dried at 130°C for 8 hours to obtain powder. The resultant polymer cake was measured for liquid content, residual Na, residual oligomer, residual NMP, reduced viscosity, cake volume, volume density, and average particle size. The results are shown in Table 2. Comparative Example 3 Polymerization condensation was conducted in the same manner as in Example 1, and 50 ml of NMP was added thereto to dilute the reaction solution. The temperature of the content at that time was 175°C. Subsequently, 150 ml of a mixed solvent of NMP and water (in a ratio of 8 : 2 by volume) was added as the pulverization solvent, to obtain a slurry. The temperature of the slurry was 125°C. The resultant slurry was filtrated, and the cake was washed with 400 ml of a mixed solvent of NMP/water at 110°C for 10 minutes and filtrated to remove the residual oligomer. Then, the residue was washed with 400 ml of water at 60 to 80°C for 30 minutes, and filtrated to remove the residual salt. This washing step was repeated five times. At the third washing, 2.5 g of oxalic dihydrate was added thereto. Then, after vacuum drying at 130°C for 8 hours, powder was obtained. The resulting cake was measured for liquid content, residual Na, residual oligomer, residual NMP, reduced viscosity, cake volume, volume density, and average particle size. The results are shown in Table 2. Comparative Example 4 Polycondensation was conducted in the same manner as in Example 1, and the reactor was air-cooled to room temperature to solidify the content. Then, the content was taken out, and 400 ml of water was added thereto, ground with a Waring Blender and filtered to obtain a polymer cake. Subsequently, 150 ml of NMP was added thereto, washed at 110°C for 10 minutes, and filtrated to remove the residual oligomer. The residue was washed with 400 ml of water at 60 to 80°C for 30 minutes, and filtrated to remove the residual salt. This washing step was repeated five times. At the third washing, 2.5 g of oxalic dihydrate was added thereto. Thereafter, the reaction product was vacuum-dried at 130°C for 8 hours to obtain a powder. The resultant polymer cake was measured for ratio of liquid content, residual Na, residual oligomer, residual NMP, reduced viscosity, cake volume, volume density, and average particle diameter. The results are shown in Table 2. Comparative Example 5 Polycondensation was conducted in the same manner as in Example 15, and after the completion of reaction, the content was cooled to 170°C, and then 500 ml of a mixed solvent (in a ratio of 8 : 2 by volume) of NMP, and water was added thereto as a pulverization solvent to obtain a polymer slurry. The temperature of the slurry was 90°C. The resultant slurry was washed and dried in the same manner as in Example 15 to obtain a powder. The polymer cake was measured for ratio of liquid content, residual K, residual NMP, reduced viscosity, cake volume, volume density, and average particle size in the same manner as in Example 1. The results are shown in Table 2.

Claims: A process for producing polycyanoaryl ether powder, which comprises reacting dihalogenobenzonitrile, a dihydric phenol and an alkali metal salt at a temperature of 140°C to 350°C for 1 to 10 hours, a molar ratio of the dihalogenobenzonitrile to the dihydric phenol being about equal and a molar ratio of the alkali metal salt to the dihalogenobenzonitrile being 1.0-3.0 to 1, in the presence of a polymerization solvent selected from the group consisting of N-alkylcarboxylic acid amides, N,N-dialkylcarboxylic acid amides, N-alkyl lactams, N-alkylcarboxyimides, sulfoxides, sulfones, cyclosulfones, nitriles, benzophenone and mixtures thereof, and thereafter (i) distilling the solvent away from the reaction mixture while applying a shearing force thereto wherein in said reaction mixture the solid polymer is present prior to distillation, or (ii) adding a pulverization solvent, said pulverization solvent being compatible with said polymerization solvent, but does not dissolve the resultant polymer, to the reaction mixture and mixing to pulverize the resultant polymer, or adding a polymerization solvent as defined above to the reaction mixture with subsequent cooling to pulverize the resultant polymer; and subsequently distilling the solvent away, or (iii) cooling the reaction mixture obtained to deposit the polymer; then pulverizing by mixing the resultant polymer without or with a pulverization solvent as defined above, or a polymerization solvent as defined above; and subsequently distilling the solvent away. The process according to Claim 1, wherein in alternative (i) the reaction mixture is cooled while applying a shearing force, and subsequently the solvent is distilled away. The process according to Claim 2, wherein the shearing force is applied by agitating in an agitation tank provided with agitating blades. The process according to Claim 1, wherein in alternative (ii) the reaction mixture is diluted by adding a polymerization solvent in such an amount that the resultant polymer may not be pulverized, The process according to Claim 1, wherein in alternative (iii) the reaction mixture is cooled under shearing. The process according to Claim 5, wherein the shearing force is applied by agitating in an agitation tank provided with agitating blades. The process according to Claim 1, wherein the dihalogenobenzonitirile is 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile, 2,4-dichlorobenzonitrile, 2,4-difluorobenzonitrile, 2-chloro-6-fluorobenzonitrile, or 2-fluoro-6-chlorobenzonitrile. The process according to Claim 1, wherein the dihydric phenol is dihydroxybenzenes, dihydroxybiphenyls, dihydroxynaphtalenes, or dihydroxybiphenyl ether. The process according to Claim 8, wherein the dihydric phenol is 1,3-dihydroxybenzene or 1,4-dihydroxybenzene. The process according to Claim 1, wherein the alkali metal salt is sodium hydrogencarbonate, sodium carbonate, potassium carbonate, or potassium hydrocarbonate. The process according to Claim 1, wherein the polymerization solvent is dimethyl sulfoxide, dimethyl sulfone, diethyl sulfone, diphenyl sulfone, sulfolane, N,N-dimethyl formamide, N-methyl pyrrolidone, N-methyl pyrrolidinone, or the mixtures thereof. The process according to Claim 1, wherein the pulverization solvent is methanol, ethanol, propanol, isopropanol, acetone, methyl ethyl ketone, water or mixtures thereof. The process according to Claim 1, wherein neutralization treatment is carried out with organic acid after the solvent is distilled away.

Inventors: SHINODA JITSUO, TAKIZAWA TOSHIHARU, YAMASAKI HIROTAKA, SHINODA, JITSUO, TAKIZAWA, TOSHIHARU, YAMASAKI, HIROTAKA, Shinoda, Jitsuo, c/o Idemitsu Kosan Co., Ltd., Takizawa, Toshiharu, c/o Idemitsu Kosan Co., Ltd., Yamasaki, Hirotaka, c/o Idemitsu Kosan Co., Ltd.
Applicants: IDEMITSU KOSAN CO, IDEMITSU KOSAN COMPANY LIMITED
Application year: 1991
Main classification: C08G65
IPC codes: C08G65, C08J3