CN114349727B - Method for reducing acetic acid residue in synthesis of 3,3', 4' -diphenyl ether dianhydride - Google Patents

Abstract

The invention relates to the technical field of purification and impurity removal, and specifically discloses a method for reducing acetic acid residue in the synthesis of 3,3',4,4'-diphenyl ether dianhydride. The method comprises the following steps: refining the crude product of 3,3',4,4'-diphenyl ether tetracarboxylic acid to obtain a refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid; The refined wet product of ',4,4'-diphenyl ether tetracarboxylic acid is dried under reduced pressure and crushed until its bulk density is ≤0.4g/cm ³ to obtain 3,3',4,4'-diphenyl ether tetracarboxylic acid Refined dry product; the refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid is dehydrated with acetic anhydride and dried under reduced pressure to obtain 3,3',4,4'-diphenyl ether dicarboxylic acid anhydride. The present invention makes the bulk density of 3,3',4,4'-diphenyl ether tetracarboxylic acid ≤0.4g/cm ³ by controlling the refining of the crude product and the conditions of cooling and crystallization, thereby reducing the residual acetic acid in the product to 0.2 %the following.

Description

A kind of method that reduces acetic acid residual in 3,3',4,4'-diphenyl ether dianhydride synthesis

technical field

The invention relates to the technical field of purification and removal of impurities, in particular to a method for reducing the residual acetic acid in the synthesis of 3,3',4,4'-diphenyl ether dianhydride.

Background technique

3,3',4,4'-Diphenyl ether dianhydride is an important monomer for synthesizing polyimide. The polyimide synthesized from it has excellent thermal processing performance and can withstand high temperature up to 400 ℃ above, and has high insulation performance. With the development of digitization, intelligence, and touch screen, polyimide, as a high-end electronic material for display screen, is also growing rapidly. Therefore, the use of 3,3',4,4'-diphenyl ether dianhydride Demand is also increasing rapidly.

3,3',4,4'-Diphenyl ether dianhydride is usually obtained by dehydration of 3,3',4,4'-diphenyl ether tetracarboxylic acid with acetic anhydride. During the reaction, the product will have obvious Acetic acid taste affects product quality, so acetic acid residue is one of the important indicators of product quality, and the general acetic acid residue index is required to be less than 0.5%. At present, residual acetic acid is mainly removed by drying under reduced pressure, but this method does not have a good purification effect on 3,3',4,4'-diphenyl ether dianhydride, and it is difficult to reduce the residual acetic acid content to 0.5%, therefore, finding a method to reduce acetic acid residues is very important for obtaining high-purity 3,3',4,4'-diphenyl ether dianhydride and using high-purity 3,3',4,4'-diphenyl ether The synthesis of polyimide from phenylene ether dianhydride is of great significance.

Contents of the invention

In view of this, the application provides a method for reducing acetic acid residues in the synthesis of 3,3',4,4'-diphenyl ether dianhydride, by controlling the refining of crude 3,3',4,4'-diphenyl ether tetracarboxylic acid And the conditions of cooling and crystallization make the bulk density ≤0.4g/cm ³ , and then reduce the residual acetic acid in the product to less than 0.2%.

In order to achieve the above-mentioned purpose of the invention, the embodiment of the present invention adopts the following technical solutions:

A method for reducing 3,3 ', 4,4'-diphenyl ether dianhydride synthesis, residual acetic acid, said method may further comprise the steps:

Step A: After mixing crude 3,3',4,4'-diphenyl ether tetracarboxylic acid, pure water and mixed acid, heat up and refine, and after refining, carry out stepwise cooling and crystallization to obtain 3,3',4,4' - Refined wet product of diphenyl ether tetracarboxylic acid, wherein the specific process of stepwise cooling and crystallization is as follows: reduce the temperature to 55°C~60°C at a cooling rate of 20°C/h~30°C/h, add 3,3',4, 4'-diphenyl ether tetracarboxylic acid seed crystal, keep warm for 0.5h~1h; then lower the temperature to 20℃~30℃ at a cooling rate of 10℃/h~20℃/h, keep warm for 0.5h~1h; 10°C/h cooling rate down to 0°C~10°C, keep warm for 0.5h~1h;

Step B. Dry and pulverize the refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid under reduced pressure until its bulk density is ≤0.4g/cm ³ to obtain 3,3',4 , Refined dry product of 4'-diphenyl ether tetracarboxylic acid;

Step C, dehydrating the refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid with acetic anhydride, cooling down to crystallize, separating solid from liquid, drying under reduced pressure, and sieving to obtain 3,3' , 4,4'-diphenyl ether dianhydride, wherein the drying process adopts intermittent replacement of inert gas.

Compared with the prior art, the method for reducing acetic acid residue in the synthesis of 3,3',4,4'-diphenyl ether dianhydride provided by the application has the following advantages:

The applicant of the present invention accidentally found in the process of a large number of experimental researches that in the process of preparing 3,3',4,4'-diphenyl ether dianhydride by dehydration of acetic anhydride, when 3,3',4,4'- When the bulk density of the diphenyl ether tetracarboxylic acid intermediate is higher than 0.5g/cm³, it is difficult to remove the residual acetic acid, and the residual acetic acid can only be reduced to about 0.6%, and only by drying under reduced pressure, 3,3', The bulk density of the 4,4'-diphenyl ether tetracarboxylic acid intermediate is also difficult to drop below 0.5g/cm³; in addition, the applicant also found that when mixed acids are used for 3,3',4,4'-diphenyl ether tetracarboxylic acid The crude product is refined, and the specific step-down temperature conditions are adopted to reduce the bulk density of 3,3',4,4'-diphenyl ether tetracarboxylic acid to below 0.4g/cm ³ and make it easy to dehydrate the acetic anhydride Remove the acetic acid residue and achieve the effect of reducing the acetic acid residue in the product to less than 2%, so as to reduce the acetic acid residue and improve the 3,3',4,4 The purity and yield of '-diphenyl ether dianhydride are improved to reduce energy consumption and improve production efficiency.

The method provided by the invention has simple operation and low cost, can effectively reduce acetic acid residue in products, and is suitable for industrial production.

The above-mentioned 3,3',4,4'-diphenyl ether tetracarboxylic acid carries out the reaction of acetic anhydride dehydration as follows:

Further optionally, in step B, the refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid is dried and pulverized under reduced pressure until its bulk density is 0.35 g/cm ³ ~0.4g /cm ³ , to obtain the refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid;

Further optionally, until the bulk density is 0.35 g/cm ³ , a refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid can be obtained.

In this application, by controlling the bulk density of the refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid, it is easy to remove the residual acetic acid after dehydration of acetic anhydride, so as to realize the improvement of 3,3',4,4 '-Diphenyl ether dianhydride quality purpose.

Optionally, in step A, the refining conditions are as follows: the rotation speed is 80 rpm to 100 rpm, the temperature is 60° C. to 100° C., and the time is 1 h to 3 h.

Further optionally, the refining temperature is 70°C-90°C; optionally, the refining temperature is 80°C.

Further optionally, the refining time is 2 hours.

Further optionally, the rotational speed of the refining is 85rpm-95rpm; optionally, the rotational speed of the refining is 90rpm.

Optionally, in step A, the temperature increase rate is 30°C/h-35°C/h; optionally, the temperature increase rate is 35°C/h.

The preferred refining conditions such as temperature, rotating speed and heating rate, etc., enable the refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid to crystallize with a unique structure and size, in order to obtain a dry product with a specific bulk density Products provide the foundation and guarantee.

Optionally, in step A, the mass ratio of the pure water to the crude 3,3',4,4'-diphenyl ether tetracarboxylic acid is 5-10:1.

Further optionally, in step A, the mass ratio of the pure water to the crude 3,3',4,4'-diphenyl ether tetracarboxylic acid is 5-8:1; optionally, the pure water The mass ratio to the crude 3,3',4,4'-diphenyl ether tetracarboxylic acid is 7:1.

Optionally, in step A, the mass ratio of the mixed acid to the crude 3,3',4,4'-diphenyl ether tetracarboxylic acid is 0.3-0.5:1.

Further optionally, in step A, the mass ratio of the mixed acid to the crude 3,3',4,4'-diphenyl ether tetracarboxylic acid is 0.4~0.5:1; optionally, the mixed acid and the The mass ratio of the crude 3,3',4,4'-diphenyl ether tetracarboxylic acid is 0.45:1.

Optionally, the mixed acid includes inorganic acid and acetic acid with a mass ratio of 2 to 5:1, and the inorganic acid is sulfuric acid or hydrochloric acid.

Further optionally, in step A, the mixed acid includes inorganic acid and acetic acid with a mass ratio of 3-4:1; optionally, the mixed acid includes inorganic acid and acetic acid with a mass ratio of 3.5:1.

Optionally, the concentration of the sulfuric acid is 40wt%~50wt%.

Optionally, the concentration of the hydrochloric acid is 30wt%-36wt%.

Optionally, the rotation speed of the stepwise cooling and crystallization is 50 rpm to 60 rpm.

Further optionally, the rotation speed of the stepwise cooling and crystallization is 55 rpm.

Optionally, in step A, the specific process of stepwise cooling and crystallization is as follows: drop the temperature down to 55 °C at a cooling rate of 25 °C/h, add 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystals, Insulate for 1 hour; then lower the temperature to 25°C at a cooling rate of 15°C/h, and hold for 1 hour; then lower the temperature to 5°C at a cooling rate of 10°C/h, and hold for 1 hour.

The preferred stepwise cooling and crystallization process, adjusting the stirring speed and cooling rate, and stepwise cooling, make the refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid crystallize with a unique structure and size, in order to obtain Dry products with specific bulk density provide the basis and guarantee.

Optionally, the mass ratio of the 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystal to the 3,3',4,4'-diphenyl ether tetracarboxylic acid crude product is 0.0005~0.002: 1.

Further optionally, the mass ratio of the 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystal to the 3,3',4,4'-diphenyl ether tetracarboxylic acid crude product is 0.001:1 .

Optionally, the purity of the 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystal is ≥99%, and the bulk density is 0.35 g/cm3-0.4 g/cm3.

Optionally, in step B, the conditions for the decompression drying are: the degree of vacuum is -0.095MPa~-0.085MPa, the steam pressure is 0.2MPa~0.3MPa, the drying temperature is 100°C~120°C, and the drying The time is 6h~10h.

Further optionally, in step B, the conditions for drying under reduced pressure are: vacuum degree is -0.095 MPa, steam pressure is 0.25 MPa, drying temperature is 110°C, and drying time is 6h~8h; optional , The drying time is 8h.

The preferred drying conditions under reduced pressure can make the bulk density of the refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid reach below 0.4g/cm ³ , providing a basis for its dehydration with acetic anhydride.

Optionally, in step B, the fineness of the crushing is 8 mesh to 20 mesh.

Further optionally, in step B, the fineness of the crushing is 10 mesh.

Optionally, in step C, the dehydration temperature of the acetic anhydride is 60° C. to 140° C. and the time is 5 to 10 hours.

Further optionally, in step C, the dehydration temperature of the acetic anhydride is 80°C to 130°C; optionally, the temperature is 120°C.

Further optionally, in step C, the dehydration time of the acetic anhydride is 6h~8h; optionally, the time is 7h.

Optionally, in step C, the mass ratio of the acetic anhydride to the refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid is 3-8:1.

Further optionally, in step C, the mass ratio of the acetic anhydride to the refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid is 4~6:1; optionally, the The mass ratio of acetic anhydride to the refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid is 5:1.

The preferred conditions for dehydration of acetic anhydride, such as temperature, reaction time and the addition ratio of the two, make the reaction of the refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid complete, and reduce the occurrence of by-products, and also Facilitate the removal of acetic acid.

Optionally, in step C, the temperature of the cooling crystallization is 0° C. to 20° C., and the time is 0.5 h to 1 h.

Further optionally, in step C, the temperature of the cooling crystallization is 10° C., and the time is 1 h.

Optionally, in step C, there is no special requirement for the method of solid-liquid separation; optionally, the solid-liquid separation adopts centrifugation.

Optionally, in step C, the aperture of the sieve is 20 mesh to 40 mesh.

Further optionally, in step C, the aperture of the sieve is 30 mesh.

Optionally, in step C, the conditions for the decompression drying are: the degree of vacuum is -0.095MPa~-0.085MPa, the steam pressure is 0.2MPa~0.3MPa, the drying temperature is 100°C~120°C, and the drying The time is 10h~14h.

Further optionally, in step C, the conditions for drying under reduced pressure are: vacuum degree is -0.095MPa, steam pressure is 0.25MPa, drying temperature is 110°C, and drying time is 11h~13h; optionally, Drying time is 12h.

The preferred vacuum drying conditions make the residue of acetic acid in the product less than 0.2%, and obtain a 3,3',4,4'-diphenyl ether dianhydride product with higher purity.

Optionally, in step C, the specific process of the intermittent replacement is: use an inert gas to unload the vacuum to 0 MPa, then stop feeding the inert gas, continue to dry under reduced pressure, and the time interval of the intermittent replacement is 1h~2h.

Further preferably, the inert gas is nitrogen.

Optionally, the decompression drying is carried out by using an enamel rotary double-cone dryer.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without making creative efforts.

Fig. 1 is the reaction equation for the dehydration of 3,3',4,4'-diphenyl ether tetracarboxylic acetic anhydride provided by the embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

In the examples of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

Example 1

The embodiment of the present application provides a method for reducing acetic acid residues in the synthesis of 3,3',4,4'-diphenyl ether dianhydride, the method comprising the following steps:

Step A. Put 100Kg of crude 3,3',4,4'-diphenyl ether tetracarboxylic acid into the anchor reaction tank, then add 700Kg of pure water and 45Kg of mixed acid, and heat up at a rate of 35°C/h at 90rpm Refining at 80°C for 2 hours, after the heat preservation is completed, use circulating water to cool down at 55rpm, drop the temperature to 55°C at a cooling rate of 25°C/h, add 0.1kg 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystals , keep warm for 1h; switch to cold brine and then drop to 25°C at a cooling rate of 15°C/h, keep warm for 1h; then drop to 5°C at a cooling rate of 10°C/h, keep warm for 1h, and centrifuge to get 3,3',4, Refined wet product of 4'-diphenyl ether tetracarboxylic acid; among them, the content of 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystals is 99.1%, and the bulk density is 0.39g/cm³; the above-mentioned mixed acid includes a concentration of 35Kg Be the acetic acid of 35wt% hydrochloric acid and 10Kg;

Step B. Put the refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid into the enamel double cone, set the steam pressure to 0.25MPa, the temperature to 110°C, the vacuum degree to -0.095MPa, and dry for 8 hours. The material is discharged and passed through a 10-mesh oscillating granulator to obtain 97kg of refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid with a bulk density of 0.35g/cm³;

Step C. Put 97Kg of the refined dry product of the above-mentioned 3,3',4,4'-diphenyl ether tetracarboxylic acid and 485Kg of acetic anhydride into a reaction tank for dehydration reaction, raise the temperature to 120°C, keep it for 7h; then cool down to 10°C, Incubate for 1 hour and centrifuge to obtain wet product of 3,3',4,4'-diphenyl ether dianhydride;

Put the above-mentioned 3,3',4,4'-diphenyl ether dianhydride wet product into the enamel rotating double cone, set the steam pressure to 0.25MPa, the temperature to 110°C, the vacuum degree to -0.095MPa, and dry for 12 hours. Replace the vacuum double-cone system with nitrogen every 1h. After the vacuum pressure in the system is released to 0MPa, stop the replacement and continue to heat up and dry; after drying, the material is discharged and passed through a 30-mesh vibrating sieve, 3, 3', 4, 4' -Diphenyl ether dianhydride finished product 84.6Kg, purity is 99.7%, yield is 97.0%, detects that its acetic acid residue is 0.15%.

Example 2

The embodiment of the present application provides a method for reducing acetic acid residues in the synthesis of 3,3',4,4'-diphenyl ether dianhydride, the method comprising the following steps:

Step A. Put 100Kg of crude 3,3',4,4'-diphenyl ether tetracarboxylic acid into the anchor reaction tank, then add 800Kg of pure water and 40Kg of mixed acid, and raise the temperature at a rate of 33°C/h under the condition of 80rpm Refining at 70°C for 3 hours, after the heat preservation is completed, use circulating water to cool down at 55rpm, and drop the temperature to 60°C at a cooling rate of 30°C/h, add 0.1kg 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystals , keep warm for 1h; switch to cold brine, then lower the temperature to 30°C at a cooling rate of 10°C/h, keep warm for 1h; then lower the temperature to 5°C at a cooling rate of 10°C/h, keep warm for 1h, and centrifuge to obtain 3,3',4, Refined wet product of 4'-diphenyl ether tetracarboxylic acid, wherein the content of 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystals is 99%, and the bulk density is 0.40g/cm³; the above-mentioned mixed acid includes 30Kg of sulfuric acid and 10Kg of acetic acid;

Step B. Put the refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid into the enamel double cone, set the steam pressure to 0.2MPa, the temperature to 110°C, the vacuum degree to -0.095MPa, and dry for 6h. The material is discharged and passed through an 8-mesh oscillating granulator to obtain 96kg of refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid, and its bulk density is 0.38g/cm³;

Step C. Put 96Kg of the above-mentioned refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid and 288Kg of acetic anhydride into a reaction tank for dehydration reaction, raise the temperature to 85°C, keep it for 10h; then cool down to 0°C, Keep warm for 0.5h, centrifuge to get 3,3',4,4'-diphenyl ether dianhydride wet product;

Put the above-mentioned 3,3',4,4'-diphenyl ether dianhydride wet product into the enamel rotating double cone, set the steam pressure to 0.3MPa, the temperature to 100°C, the vacuum degree to -0.095MPa, and dry for 14 hours. Replace the vacuum double-cone system with nitrogen every 1h. After the vacuum pressure in the system is released to 0MPa, stop the replacement and continue to heat up and dry; after drying, the material is discharged and passed through a 20-mesh vibrating sieve, 3, 3', 4, 4' - The finished product of diphenyl ether dianhydride is 82.5Kg, the purity is 99.65%, the yield is 95.58%, and the residual acetic acid is 0.18%.

Example 3

The embodiment of the present application provides a method for reducing acetic acid residues in the synthesis of 3,3',4,4'-diphenyl ether dianhydride, the method comprising the following steps:

Step A. Put 100Kg of crude 3,3',4,4'-diphenyl ether tetracarboxylic acid into the anchor reaction tank, then add 600Kg of pure water and 50Kg of mixed acid, and raise the temperature at a rate of 30°C/h under the condition of 100rpm Refined at 90°C for 1 hour, after the heat preservation, use circulating water to cool down at 60rpm, drop the temperature to 55°C at a rate of 25°C/h, add 0.05kg 3,3',4,4'-diphenyl ether tetracarboxylic acid seed , keep warm for 1h; switch to cold brine and then drop to 20°C at a cooling rate of 20°C/h, keep warm for 1h; then drop to 0°C at a cooling rate of 5°C/h, keep warm for 1h, and centrifuge to get 3,3',4, Refined wet product of 4'-diphenyl ether tetracarboxylic acid, wherein the content of 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystals is 99.1%, and the bulk density is 0.35g/cm³; the concentration of the above-mentioned mixed acid including 40Kg is The acetic acid of 35wt% hydrochloric acid and 10Kg;

Step B. Put the refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid into the enamel double cone, set the steam pressure to 0.3MPa, the temperature to 100°C, the vacuum degree to -0.085MPa, and dry for 10h. The material was discharged and passed through a 10-mesh oscillating granulator to obtain 96.2kg of refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid, with a bulk density of 0.37g/cm³;

Step C. Put 96.2Kg of the refined dry product of the above-mentioned 3,3',4,4'-diphenyl ether tetracarboxylic acid and 481Kg of acetic anhydride into the reaction tank for dehydration reaction, raise the temperature to 120°C, keep it warm for 8h; then cool down to 10°C , keep warm for 1h, and centrifuge to obtain the wet product of 3,3',4,4'-diphenyl ether dianhydride;

Put the above-mentioned 3,3',4,4'-diphenyl ether dianhydride wet product into the enamel rotating double cone, set the steam pressure to 0.25MPa, the temperature to 110°C, the vacuum degree to -0.095MPa, and dry for 13 hours. Replace the vacuum double-cone system with nitrogen every 1h. After the vacuum pressure in the system is released to 0MPa, stop the replacement and continue to heat up and dry; after drying, the material is discharged and passed through a 30-mesh vibrating sieve, 3, 3', 4, 4' - The finished product of diphenyl ether dianhydride is 82.64Kg, the purity is 99.7%, the yield is 96.74%, and the residual acetic acid is 0.17%.

Example 4

The embodiment of the present application provides a method for reducing acetic acid residues in the synthesis of 3,3',4,4'-diphenyl ether dianhydride, the method comprising the following steps:

Step A. Put 100Kg of crude 3,3',4,4'-diphenyl ether tetracarboxylic acid into the anchor reaction tank, then add 500Kg of pure water and 45Kg of mixed acid, and raise the temperature at a rate of 35°C/h under the condition of 90rpm Refining at 60°C for 2.5h, after the heat preservation is completed, use circulating water to cool down at 50rpm, drop the temperature to 55°C at a cooling rate of 20°C/h, add 0.05kg of 3,3',4,4'-diphenyl ether tetracarboxylic acid crystals and keep warm for 1h; switch to cold brine and then lower the temperature to 25°C at a cooling rate of 15°C/h, keep warm for 1h; then lower the temperature to 10°C at a cooling rate of 10°C/h, keep warm for 1h, and centrifuge to obtain 3,3',4 , 4'-diphenyl ether tetracarboxylic acid refined wet product, wherein the content of 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystals is 99.1%, and the bulk density is 0.4g/cm³; the above-mentioned mixed acid includes a concentration of 30Kg Be the acetic acid of 35wt% hydrochloric acid and 15Kg;

Step B. Put the refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid into the enamel double cone, set the steam pressure to 0.25MPa, the temperature to 115°C, the vacuum degree to -0.095MPa, and dry for 8 hours. The material is discharged and passed through a 20-mesh oscillating granulator to obtain 96kg of refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid, with a bulk density of 0.35g/cm³;

Step C. Put 96Kg of the refined dry product of the above-mentioned 3,3',4,4'-diphenyl ether tetracarboxylic acid and 384Kg of acetic anhydride into a reaction tank for dehydration reaction, raise the temperature to 80°C, keep it for 7h; then cool down to 15°C, Incubate for 0.8h and centrifuge to obtain wet product of 3,3',4,4'-diphenyl ether dianhydride;

Put the above-mentioned 3,3',4,4'-diphenyl ether dianhydride wet product into the enamel rotating double cone, set the steam pressure to 0.3MPa, the temperature to 110°C, the vacuum degree to -0.090MPa, and dry for 12 hours. Replace the vacuum double-cone system with nitrogen every 2 hours. After the vacuum pressure in the system is released to 0MPa, stop the replacement and continue to heat up and dry; after drying, the material is discharged and passed through a 40-mesh vibrating sieve, 3, 3', 4, 4' -Diphenyl ether dianhydride finished product 82.7Kg, purity is 99.6%, yield is 95.76%, detects that its acetic acid residue is 0.18%.

Example 5

The embodiment of the present application provides a method for reducing acetic acid residues in the synthesis of 3,3',4,4'-diphenyl ether dianhydride, the method comprising the following steps:

Step A. Put 100Kg of crude 3,3',4,4'-diphenyl ether tetracarboxylic acid into the anchor reaction tank, then add 1000Kg of pure water and 30Kg of mixed acid, and heat up at a rate of 35°C/h at 95rpm Refining at 100°C for 2 hours, after the heat preservation is completed, use circulating water to cool down at 60rpm, drop the temperature to 60°C at a cooling rate of 25°C/h, add 0.1kg of 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystals , keep warm for 1h; switch to cold brine, then drop to 30°C at a cooling rate of 20°C/h, keep warm for 1h; then drop to 5°C at a cooling rate of 5°C/h, keep warm for 1h, and centrifuge to obtain 3,3',4, Refined wet product of 4'-diphenyl ether tetracarboxylic acid, wherein the content of 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystals is 99.2%, and the bulk density is 0.38g/cm³; the concentration of the above-mentioned mixed acid including 25Kg is The acetic acid of 35wt% hydrochloric acid and 5Kg;

Step B. Put the refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid into the enamel double cone, set the steam pressure to 0.3MPa, the temperature to 120°C, the vacuum degree to -0.090MPa, and dry for 6h. The material is discharged and passed through a 10-mesh oscillating granulator to obtain 95kg of refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid, with a bulk density of 0.36g/cm³;

Step C. Put 95Kg of the refined dry product of the above-mentioned 3,3',4,4'-diphenyl ether tetracarboxylic acid and 760Kg of acetic anhydride into a reaction tank for dehydration reaction, raise the temperature to 140°C, keep it for 5h; then cool down to 5°C, Keep warm for 0.5h, centrifuge to get 3,3',4,4'-diphenyl ether dianhydride wet product;

Put the above-mentioned 3,3',4,4'-diphenyl ether dianhydride wet product into the enamel rotating double cone, set the steam pressure to 0.2MPa, the temperature to 110°C, the vacuum degree to -0.095MPa, and dry for 12 hours. Replace the vacuum double-cone system with nitrogen every 2 hours. After the vacuum pressure in the system is released to 0MPa, stop the replacement and continue to heat up and dry; after drying, the material is discharged and passed through a 30-mesh vibrating sieve, 3, 3', 4, 4' -Diphenyl ether dianhydride finished product 81.7Kg, purity is 99.69%, yield is 95.68%, detects that its acetic acid residue is 0.16%.

Example 6

The embodiment of the present application provides a method for reducing acetic acid residues in the synthesis of 3,3',4,4'-diphenyl ether dianhydride, the method comprising the following steps:

Step A. Put 100Kg of crude 3,3',4,4'-diphenyl ether tetracarboxylic acid into the anchor reaction tank, then add 700Kg of pure water and 45Kg of mixed acid, and raise the temperature at a rate of 32°C/h under the condition of 85rpm Refined at 85°C for 2.5h, after the heat preservation is completed, use circulating water to cool down at 55rpm, drop the temperature to 55°C at a cooling rate of 25°C/h, add 0.1kg of 3,3',4,4'-diphenyl ether tetracarboxylic acid crystals and keep warm for 1h; switch to cold brine and then lower the temperature to 25°C at a cooling rate of 15°C/h, keep warm for 1h; then lower the temperature to 5°C at a cooling rate of 10°C/h, keep warm for 1h, and centrifuge to obtain 3,3',4 , 4'-diphenyl ether tetracarboxylic acid refined wet product, wherein the content of 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystals is 99%, and the bulk density is 0.39g/cm³; the above-mentioned mixed acid includes a concentration of 35Kg Be the acetic acid of 35wt% hydrochloric acid and 10Kg;

Step B. Put the refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid into the enamel double cone, set the steam pressure to 0.25MPa, the temperature to 110°C, the vacuum degree to -0.095MPa, and dry for 9 hours. The material is discharged and passed through a 15-mesh oscillating granulator to obtain 96.5kg of refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid, and its bulk density is 0.35g/cm³;

Step C. Put 96.5Kg of the above-mentioned refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid and 485Kg of acetic anhydride into a reaction tank for dehydration reaction, raise the temperature to 120°C, keep it warm for 6h; then cool down to 10°C , keep warm for 1h, and centrifuge to obtain the wet product of 3,3',4,4'-diphenyl ether dianhydride;

Put the above-mentioned 3,3',4,4'-diphenyl ether dianhydride wet product into the enamel rotating double cone, set the steam pressure to 0.25MPa, the temperature to 120°C, the vacuum degree to -0.085MPa, and dry for 12 hours. Replace the vacuum double-cone system with nitrogen every 2 hours. After the vacuum pressure in the system is released to 0MPa, stop the replacement and continue to heat up and dry; after drying, the material is discharged and passed through a 30-mesh vibrating sieve, 3, 3', 4, 4' - The finished product of diphenyl ether dianhydride is 82.95Kg, the purity is 99.7%, the yield is 95.64%, and the acetic acid residue is 0.16%.

In order to better illustrate the technical solution of the present invention, a further comparison is made below through comparative examples and examples of the present invention.

Comparative example 1

This comparative example provides a method for reducing 3,3',4,4'-diphenyl ether dianhydride and acetic acid residues in the synthesis, said method comprising the following steps:

Step A, the concentration that mixed acid is replaced with 35Kg is the propionic acid of 35wt% hydrochloric acid and 10Kg, and the condition in all the other steps A is constant;

Step B. Put the refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid into the enamel double cone, set the steam pressure to 0.25MPa, the temperature to 110°C, the vacuum degree to -0.095MPa, and dry for 8 hours. The material is discharged and passed through a 10-mesh oscillating granulator to obtain 92 kg of refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid, and its bulk density is 0.52g/cm³;

Step C. Put 92Kg of the above-mentioned refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid and 460Kg of acetic anhydride into a reaction tank for dehydration reaction, raise the temperature to 120°C, keep it for 7h; then cool down to 10°C, Incubate for 1 hour and centrifuge to obtain wet product of 3,3',4,4'-diphenyl ether dianhydride;

Put the above-mentioned 3,3',4,4'-diphenyl ether dianhydride wet product into the enamel rotating double cone, set the steam pressure to 0.25MPa, the temperature to 110°C, the vacuum degree to -0.095MPa, and dry for 12 hours. Replace the vacuum double-cone system with nitrogen every 1h. After the vacuum pressure in the system is released to 0MPa, stop the replacement and continue to heat up and dry; after drying, the material is discharged and passed through a 30-mesh vibrating sieve, 3, 3', 4, 4' -The finished product of diphenyl ether dianhydride is 74.5Kg, the purity is 99.28%, the yield is 89.73%, and its acetic acid residue is 0.65%.

Comparative example 2

This comparative example provides a method for reducing 3,3',4,4'-diphenyl ether dianhydride and acetic acid residues in the synthesis, said method comprising the following steps:

Step A, mixed acid is replaced with the nitric acid of 35Kg and the acetic acid of 10Kg, the condition in all the other steps A is constant, and wherein the concentration of nitric acid is 35wt%;

Step B. Put the refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid into the enamel double cone, set the steam pressure to 0.25MPa, the temperature to 110°C, the vacuum degree to -0.095MPa, and dry for 8 hours. The material was discharged and passed through a 10-mesh oscillating granulator to obtain 91.5kg of refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid, with a bulk density of 0.58g/cm³;

Step C. Put 91.5 Kg of the refined dry product of the above-mentioned 3,3',4,4'-diphenyl ether tetracarboxylic acid and 457.5 Kg of acetic anhydride into a reaction tank for dehydration reaction, raise the temperature to 120°C, and keep it warm for 7 hours; then cool down to 10 ℃, keep warm for 1h, and centrifuge to obtain the wet product of 3,3',4,4'-diphenyl ether dianhydride;

Put the above-mentioned 3,3',4,4'-diphenyl ether dianhydride wet product into the enamel rotating double cone, set the steam pressure to 0.25MPa, the temperature to 110°C, the vacuum degree to -0.095MPa, and dry for 12 hours. Replace the vacuum double-cone system with nitrogen every 1h. After the vacuum pressure in the system is released to 0MPa, stop the replacement and continue to heat up and dry; after drying, the material is discharged and passed through a 30-mesh vibrating sieve, 3, 3', 4, 4' -The finished product of diphenyl ether dianhydride is 73.83Kg, the purity is 99.25%, the yield is 89.37%, and its acetic acid residue is 0.68%.

Comparative example 3

This comparative example provides a method for reducing 3,3',4,4'-diphenyl ether dianhydride and acetic acid residues in the synthesis, said method comprising the following steps:

Step A. Put 100Kg of crude 3,3',4,4'-diphenyl ether tetracarboxylic acid into the anchor reaction tank, then add 700Kg of pure water and 45Kg of mixed acid, and heat up at a rate of 35°C/h at 90rpm Refined at 80°C for 2 hours, after the heat preservation is completed, use circulating water to cool down at 55rpm, drop the temperature to 55°C at a cooling rate of 35°C/h, add 0.1kg 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystals , keep warm for 1h; switch to cold brine, then drop to 25°C at a cooling rate of 25°C/h, keep warm for 1h; then drop to 5°C at a cooling rate of 15°C/h, keep warm for 1h, and centrifuge to get 3,3',4, Refined wet product of 4'-diphenyl ether tetracarboxylic acid; wherein, the content of 3,3',4,4'-diphenyl ether tetracarboxylic acid seed crystals is 99.1%, and the bulk density is 0.39g/cm³; the above-mentioned mixed acid includes 35Kg of hydrochloric acid and 10Kg of acetic acid;

Step B. Put the refined wet product of 3,3',4,4'-diphenyl ether tetracarboxylic acid into the enamel double cone, set the steam pressure to 0.25MPa, the temperature to 110°C, the vacuum degree to -0.095MPa, and dry for 8 hours. The material was discharged and passed through a 10-mesh oscillating granulator to obtain 92.5 kg of refined dry product of 3,3',4,4'-diphenyl ether tetracarboxylic acid with a bulk density of 0.55g/cm³;

Step C. Put 92.5 Kg of the refined dry product of the above-mentioned 3,3',4,4'-diphenyl ether tetracarboxylic acid and 462.5 Kg of acetic anhydride into a reaction tank for dehydration reaction, raise the temperature to 120°C, and keep it warm for 7 hours; then cool down to 10 ℃, keep warm for 1h, and centrifuge to obtain the wet product of 3,3',4,4'-diphenyl ether dianhydride;

Put the above-mentioned 3,3',4,4'-diphenyl ether dianhydride wet product into the enamel rotating double cone, set the steam pressure to 0.25MPa, the temperature to 110°C, the vacuum degree to -0.095MPa, and dry for 12 hours. Replace the vacuum double-cone system with nitrogen every 1h. After the vacuum pressure in the system is released to 0MPa, stop the replacement and continue to heat up and dry; after drying, the material is discharged and passed through a 30-mesh vibrating sieve, 3, 3', 4, 4' -The finished product of diphenyl ether dianhydride is 74.5Kg, the purity is 99.20%, the yield is 89.17%, and its acetic acid residue is 0.72%.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Any modification, equivalent replacement or improvement made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (9)

1. A method for reducing acetic acid residue in the synthesis of 3,3', 4' -diphenyl ether dianhydride is characterized in that: the method comprises the following steps:

step A, mixing the crude 3,3', 4' -diphenyl ether tetracarboxylic acid, pure water and mixed acid, heating for refining, and after finishing refining, carrying out stepped cooling crystallization to obtain a refined wet 3,3', 4' -diphenyl ether tetracarboxylic acid, wherein the specific process of the stepped cooling crystallization is as follows: cooling to 55-60 ℃ at the cooling rate of 20-30 ℃/h, adding 3,3', 4' -diphenyl ether tetracarboxylic acid seed crystal, and keeping the temperature for 0.5-1 h; then reducing the temperature to 20-30 ℃ at the cooling rate of 10-20 ℃/h, and preserving the temperature for 0.5-1 h; reducing the temperature to 0-10 ℃ at a cooling rate of 5-10 ℃/h, and keeping the temperature for 0.5-1 h, wherein the mass ratio of the mixed acid is 2-5;

step B, drying and crushing the refined wet product of the 3,3', 4' -diphenyl ether tetracarboxylic acid until the bulk density is less than or equal to 0.4g/cm ³ Obtaining the refined dried product of 3,3', 4' -diphenyl ether tetracarboxylic acid, wherein the reduced pressure drying condition is as follows: the vacuum degree is-0.095 MPa to-0.085 MPa, the steam pressure is 0.2MPa to 0.3MPa, the drying temperature is 100 ℃ to 120 ℃, and the drying time is 6 to 10 hours;

and step C, dehydrating the refined dry 3,3', 4' -diphenyl ether tetracarboxylic acid product by acetic anhydride, cooling and crystallizing, carrying out solid-liquid separation, drying under reduced pressure, and sieving to obtain 3,3', 4' -diphenyl ether dianhydride, wherein inert gas is adopted for intermittent displacement in the reduced pressure drying process, the dehydration temperature of the acetic anhydride is 60-140 ℃, the time is 5-10 h, the cooling and crystallizing temperature is 0-20 ℃, the time is 0.5-1 h, and the reduced pressure drying condition is as follows: the vacuum degree is-0.095 MPa to-0.085 MPa, the steam pressure is 0.2MPa to 0.3MPa, the drying temperature is 100 ℃ to 120 ℃, and the drying time is 10 to 14 hours.

2. The method for reducing acetic acid residue in the synthesis of 3,3', 4' -diphenyl ether dianhydride according to claim 1, wherein: in the step A, the refining conditions are as follows: the rotating speed is 80rpm to 100rpm, the temperature is 60 ℃ to 100 ℃, and the time is 1h to 3h; and/or

In the step A, the temperature rise rate of the temperature rise is 30-35 ℃/h.

3. The method for reducing acetic acid residue in the synthesis of 3,3', 4' -diphenyl ether dianhydride according to claim 1, wherein: in the step A, the mass ratio of the pure water to the crude product of 3,3', 4' -diphenyl ether tetracarboxylic acid is 5-10; and/or

In the step A, the mass ratio of the mixed acid to the crude product of the 3,3', 4' -diphenyl ether tetracarboxylic acid is 0.3-0.5.

4. The method for reducing acetic acid residues in the synthesis of 3,3', 4' -diphenyl ether dianhydride according to claim 1, wherein: in the step A, the rotating speed of the step cooling crystallization is 50-60 rpm; and/or

In the step A, the specific process of the step cooling crystallization is as follows: cooling to 55 deg.C at a rate of 25 deg.C/h, adding 3,3', 4' -diphenyl ether tetracarboxylic acid seed crystal, and maintaining for 1h; then reducing the temperature to 25 ℃ at the cooling rate of 15 ℃/h, and preserving the heat for 1h; then the temperature is reduced to 5 ℃ at the cooling rate of 10 ℃/h, and the temperature is kept for 1h.

5. The method for reducing acetic acid residue in the synthesis of 3,3', 4' -diphenyl ether dianhydride according to claim 1, wherein: the mass ratio of the 3,3', 4' -diphenyl ether tetracarboxylic acid seed crystal to the crude 3,3', 4' -diphenyl ether tetracarboxylic acid is 0.0005-0.002; and/or

The purity of the 3,3', 4' -diphenyl ether tetracetic acid crystal is more than or equal to 99 percent, and the bulk density is 0.35g/cm ³ ～0.4g/cm ³ 。

6. The method for reducing acetic acid residue in the synthesis of 3,3', 4' -diphenyl ether dianhydride according to claim 1, wherein:

in the step B, the fineness of the crushing is 8-20 meshes.

7. The method for reducing acetic acid residue in the synthesis of 3,3', 4' -diphenyl ether dianhydride according to claim 1, wherein:

in the step C, the mass ratio of the acetic anhydride to the refined dry 3,3', 4' -diphenyl ether tetracarboxylic acid is 3-8; and/or

In the step C, the aperture of the sieve is 20-40 meshes.

8. The method for reducing acetic acid residue in the synthesis of 3,3', 4' -diphenyl ether dianhydride according to claim 1, wherein: in the step C, the intermittent replacement specifically comprises the following steps: and (3) adopting inert gas to unload the vacuum degree to 0MPa, then stopping introducing the inert gas, and continuing to perform reduced pressure drying, wherein the time interval of the intermittent replacement is 1-2 h.

9. The method for reducing acetic acid residues in the synthesis of 3,3', 4' -diphenyl ether dianhydride according to claim 1, wherein: and the reduced pressure drying adopts an enamel rotating double-cone dryer for drying.

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