Use of a heterogeneous neutralizing agent in the preparation of cellulose acetate butyrate

Abstract

The application discloses application of a heterogeneous neutralizing agent in preparation of cellulose acetate butyrate, and the application comprises the following steps: adding the heterogeneous neutralizing agent into a cellulose acetate butyrate hydrolysis reaction solution, and filtering after neutralization treatment to obtain a cellulose acetate butyrate neutralization reaction solution; the heterogeneous neutralizing agent is a metal oxide / support composite material; the metal oxide is at least one of MgO, ZnO and CaO; and the support is at least one of montmorillonite, kaolin, ZSM-5 molecular sieve and UIO-66. The application method can increase filterability of sulfate, improve production efficiency, reduce generation of sewage, and prepare cellulose acetate butyrate with low sulfur content.

Description

TECHNICAL FIELD

[0001] The application relates to an application method, in particular to application of a heterogeneous neutralizing agent in preparation of cellulose acetate butyrate. BACKGROUND

[0002] Cellulose acetate butyrate (CAB) is an important cellulose derivative, which has excellent performance and is compatible with various resins, and can be applied to various fields as a leveling agent, a film-forming material and the like of a coating.

[0003] An industrial production method of CAB mainly comprises the steps of activation, esterification, hydrolysis, neutralization, filtration, sedimentation, washing and drying, and the like. Due to the complicated steps, the yield of CAB is relatively low. In industry, concentrated sulfuric acid is generally used as a catalyst to catalyze the esterification reaction of hydroxyl groups on cellulose and anhydride; in the hydrolysis, sulfuric acid is used as a catalyst to catalyze the hydrolysis of ester groups on cellulose, so that the content of hydroxyl groups in CAB reaches the requirement; however, if sulfuric acid remains in the reaction system, cellulose sulfate generated will cause CAB to yellow at high temperature, affecting the application performance, and therefore, after the hydrolysis is completed, the sulfuric acid in the reaction system needs to be neutralized to generate metal sulfate precipitate, and through the next step of filtration, the clear CAB reaction solution is obtained.

[0004] However, this involves a new problem, if the generated sulfate is not completely filtered, the sulfate is wrapped in the product in the sedimentation process, causing the sulfur element in the product to exceed the standard, and when the product is dissolved in a resin solution for downstream application, the existence of the sulfate makes the turbidity of the resin solution exceed the standard, affecting the film-forming quality.

[0005] Patent CN104193829B adds magnesium acetate to the reaction system to neutralize sulfuric acid; and patent CN102898530A adds sodium butyrate to the reaction system to neutralize sulfuric acid. These neutralizing agents have two problems, one is that the generated magnesium sulfate or sodium sulfate is slightly soluble in water, and the dissolved part cannot be removed by filtration, which is easy to cause the sulfur element in the product to exceed the standard; the other is that the magnesium sulfate, sodium sulfate or other kinds of sulfate generally have the characteristic of small particle size, and are distributed in the form of fine powder in the reaction system, increasing the difficulty of filtration, and in the industrialization process, higher filtration precision is required, increasing the filtration time and equipment investment.

[0006] Patent CN113788899A adds sulfate seed crystals to the hydrolysis liquid, and then adds acetate or butyrate neutralizing agent, and uses the ultrasonic crystallization method to strengthen the salting-out process, so as to precipitate and separate the sulfate in the reaction system, but the required time for ultrasonic and standing is long, greatly reducing the production efficiency, and therefore, the method is not suitable for industrial production.

[0007] Therefore, the prior art can basically achieve the separation of sulfate in the cellulose acetate butyrate reaction system, but it is difficult to control the content of sulfur in the reaction system in a very low range due to the above reasons, and if further removal is required, the equipment investment and production difficulty will be increased; moreover, a large amount of water is consumed in the existing neutralization process when removing sulfate, and the generation of a large amount of salt-containing wastewater increases the pressure of environmental protection treatment. Therefore, an improved neutralization process is needed to improve the product quality and production efficiency of cellulose acetate butyrate and reduce the generation of wastewater. SUMMARY

[0008] In order to solve the above technical problems, the application provides an application of a heterogeneous neutralizing agent in the preparation of cellulose acetate butyrate. The application method can increase the filterability of sulfate, improve the production efficiency, reduce the generation of wastewater, and prepare cellulose acetate butyrate with low sulfur content.

[0009] To achieve the above purpose, the technical scheme adopted by the application is as follows:

[0010] An application of a heterogeneous neutralizing agent in the preparation of cellulose acetate butyrate, comprising: adding a heterogeneous neutralizing agent to a cellulose acetate butyrate hydrolysis reaction solution, filtering after neutralization treatment, and obtaining a cellulose acetate butyrate neutralization reaction solution;

[0011] The heterogeneous neutralizing agent is a metal oxide / support composite material; the metal oxide is at least one of MgO, ZnO and CaO; and the support is at least one of montmorillonite, kaolin, ZSM-5 molecular sieve and UIO-66;

[0012] Preferably, the content of the metal oxide in the composite material is 0.5-2wt%.

[0013] The heterogeneous neutralizing agent is composed of two parts, the metal oxide is anchored on the support as an active site, and the sulfate generated in the neutralization reaction is also anchored on the support. Since the particle size of the support is large, the filtering effect is better, the sulfate in the system can be removed more efficiently, and the filter cloth is not easy to block during filtering, so the precision of the filter cloth can be reduced, and the industrial production and operation are easier to realize; secondly, the porous support has a certain water absorption, which can adsorb water in the system during the neutralization process, thereby reducing the water content of the system, and a small amount of sulfate separated from the support is more difficult to dissolve in the reaction system, which can be separated by filtration to further reduce the content of metal ions in the product.

[0014] As a preferred embodiment of the application, the neutralization treatment conditions are 0.2-1h of neutralization reaction at 40-60℃.

[0015] As a preferred embodiment of the application, the amount of the heterogeneous neutralizing agent is 0.1-1% of the mass of the cellulose acetate butyrate hydrolysis reaction solution.

[0016] As a preferred embodiment of the present application, the composition of the cellulose acetate butyrate hydrolysis reaction solution comprises: 10-30% cellulose acetate butyrate, 60-80% butyric acid, 1-10% acetic acid, 0.05-0.2% sulfuric acid, 1-3% water, the total mass of the above components being 100%.

[0017] As a feasible example provided by the present application, the cellulose acetate butyrate hydrolysis reaction solution can be prepared by the following method:

[0018] (1) Activation: soak 100-200 mesh cellulose powder in 5-50 times mass of acetic acid for 1-10 h, separate the acetic acid, and obtain activated cellulose powder;

[0019] (2) Esterification: dissolve the activated cellulose powder in butyric acid, and react with acetic anhydride and butyric anhydride under the catalysis of sulfuric acid to obtain an esterification reaction solution. The mass ratio of each component is cellulose powder: acetic anhydride: butyric anhydride: butyric acid: sulfuric acid = 1: (0.5-3): (1-6): (1-10): (0.05-2); the reaction temperature is 30-80°C, and the reaction time is 2-8 h;

[0020] (3) Hydrolysis: add a certain amount of water to the esterification reaction solution to carry out hydrolysis reaction, and obtain the cellulose acetate butyrate hydrolysis reaction solution, wherein the amount of water added is 0.1-2 times the mass of the cellulose powder in step (1), the reaction temperature is 30-80°C, and the reaction time is 5-30 h.

[0021] As a preferred embodiment of the present application, the filtration method is pressure filtration, and the pressure is 0.1-0.3 MPaG. Preferably, the filtration precision of the filter material selected is 50-80 μm.

[0022] As a preferred embodiment of the present application, the heterogeneous neutralizing agent is prepared by any one or more of the following methods: impregnation method, deposition precipitation method, ion exchange method, and coprecipitation method.

[0023] As a feasible example, the heterogeneous neutralizing agent is prepared by the following method:

[0024] (1) Dissolve at least one of magnesium salt, zinc salt, and calcium salt in water, then add a carrier, mix uniformly, and slowly evaporate the excess water to obtain a dry solid;

[0025] (2) Put the solid into a tube furnace for calcination treatment to obtain the heterogeneous neutralizing agent.

[0026] Further, the magnesium salt is selected from one or more of magnesium acetate, magnesium chloride, and magnesium nitrate;

[0027] The zinc salt is selected from one or more of zinc acetate, zinc chloride, and zinc nitrate.

[0028] The calcium salt is selected from one or more of calcium acetate, calcium chloride, calcium nitrate.

[0029] Further, in the above preparation method, the mixing and drying are conventional operations in the art, and in some examples, the mixing is preferably performed for 0.5-5 hours before drying in a rotary evaporator.

[0030] Further, in the above preparation method, the calcination conditions are, for example, heating to a temperature of 400-600°C in an air atmosphere for 4-6 hours.

[0031] As a preferred embodiment of the present application, the average particle size of the heterogeneous neutralizing agent is 100-200 μm.

[0032] The heterogeneous neutralizing agent provided by the present application can stably exist in the cellulose acetate butyrate hydrolysis reaction solution, can be simply and efficiently removed after completing the neutralization task, is easier to realize and operate in industrial production, and is beneficial to reducing the residual sulfate content in the system and improving product quality. DETAILED DESCRIPTION

[0033] The present application is further described below through specific examples, which are only used to illustrate the present application and do not limit the scope of the present application.

[0034] The raw materials and reagents used in the following examples of the present application are commercially available unless otherwise specified.

[0035] The cellulose acetate butyrate hydrolysis reaction solution is prepared by the following method:

[0036] (1) Activation: cellulose powder is soaked in 50 times the mass of acetic acid for 10 hours, and the acetic acid is separated to obtain activated cellulose powder;

[0037] (2) Esterification: the activated cellulose powder is dissolved in butyric acid, and reacted with acetic anhydride and butyric anhydride under the catalysis of sulfuric acid to obtain an esterification reaction solution. The mass ratio of each component is activated cellulose powder: acetic anhydride: butyric anhydride: butyric acid: sulfuric acid = 1:0.6:6:6:0.3; the reaction temperature is 50°C, and the reaction time is 5 hours;

[0038] (3) Hydrolysis: water is added to the esterification reaction solution in an amount equal to the mass of the cellulose powder in step (1) to perform a hydrolysis reaction, and a cellulose acetate butyrate hydrolysis reaction solution is obtained. In the hydrolysis reaction, the reaction temperature is 50°C, and the reaction time is 20 hours. The composition of the obtained hydrolysis reaction solution includes 13.4% cellulose acetate butyrate, 79.5% butyric acid, 4.0% acetic acid, 0.15% sulfuric acid, and 2.95% water.

[0039] The neutralizing agents provided in the following embodiments and comparative examples of the present invention, after being applied to the cellulose acetate butyrate hydrolysis reaction solution for neutralization, are filtered to obtain the filtrate. The filtrate is then uniformly processed according to the following method to obtain the cellulose acetate butyrate product, which is used to detect the residual sulfur and metal content in the product:

[0040] The filtrate obtained from filtration is pumped into a large amount of water at a rate of 100 mL / min, and stirred and precipitated at a rate of 200-600 r / min to obtain a slurry containing cellulose acetate butyrate, butyric acid, and acetic acid. Solid separation is performed to obtain a solid, which is then washed and dried to obtain the cellulose acetate butyrate product.

[0041] In the following embodiments of the present invention, the oxide content in the heterogeneous catalyst was determined by X-ray fluorescence spectrometry (EDX); the particle size was determined by laser particle size analyzer; and the sulfur and metal element content in the cellulose acetate butyrate product was tested by inductively coupled plasma mass spectrometry (ICP-MS).

[0042] Example 1

[0043] 10g of Mg(CH3COO)2·4H2O was dissolved in 200g of water. After complete dissolution, 10g of montmorillonite was added, and the mixture was stirred for 2 hours. The solution was then dried in a rotary evaporator. The rotary evaporator was set to a temperature of 50℃ and a vacuum of 20kPa. The dried powder was placed in a tube furnace and calcined in air at 400℃ for 4 hours at an air flow rate of 30mL / min to obtain a heterogeneous neutralizing agent. EDX analysis showed that the MgO content in the heterogeneous neutralizing agent in this example was 1.85wt%, and the average particle size of the product was 125μm.

[0044] Take 1g of the heterogeneous neutralizing agent prepared above and add it to 1000g of cellulose acetate butyrate hydrolysis reaction solution. Stir and react at 40℃ for 1h, then filter and separate. The filtration pressure is 0.3MPa, and the filtration precision of the filter material is 50μm. The filtration time is 3min. The resulting filtrate is clear, and the turbidity is measured to be 1.2NTU.

[0045] The above filtrate was post-processed to obtain cellulose acetate butyrate product. ICP-MS analysis showed that the sulfur content was 18 ppm and the Mg content was <10 ppm.

[0046] Example 2

[0047] 5g of Zn(CH3COO)2·4H2O was dissolved in 100g of water. After complete dissolution, 10g of kaolin was added, and the mixture was stirred for 2 hours. The solution was then dried in a rotary evaporator. The rotary evaporator was set to a temperature of 60℃ and a vacuum of 30kPa. The dried powder was placed in a tube furnace and calcined in air at 500℃ for 5 hours at an air flow rate of 40mL / min to obtain a heterogeneous neutralizing agent. EDX analysis showed that the ZnO content in the heterogeneous neutralizing agent in this example was 0.93wt%, and the average particle size of the product was 158μm.

[0048] Take 5g of the heterogeneous neutralizing agent prepared above and add it to 1000g of cellulose acetate butyrate hydrolysis reaction solution. Stir the reaction at 50℃ for 0.5h, filter and separate the solution. The filtration pressure is 0.2MPa, and the filtration precision of the filter material is 60μm. The filtration time is 5min. The resulting filtrate is clear, and the turbidity is measured to be 1.6NTU.

[0049] The above filtrate was post-processed to obtain cellulose acetate butyrate product. ICP-MS analysis showed that the sulfur content was 27 ppm and the Zn content was <10 ppm.

[0050] Example 3

[0051] 3g of Ca(CH3COO)2·H2O was dissolved in 30g of water. After complete dissolution, 3g of ZSM-5 molecular sieve was added, and the mixture was stirred for 2 hours. The solution was then dried in a rotary evaporator. The rotary evaporator was set to a temperature of 70℃ and a vacuum of 40kPa. The dried powder was placed in a tube furnace and calcined in air at 600℃ for 4 hours at an air flow rate of 50mL / min to obtain a heterogeneous neutralizing agent. EDX analysis showed that the CaO content in the heterogeneous neutralizing agent in this example was 1.37wt%, and the average particle size of the product was 132μm.

[0052] Take 10g of the heterogeneous neutralizing agent prepared above and add it to 1000g of cellulose acetate butyrate hydrolysis reaction solution. Stir the reaction at 60℃ for 0.2h, filter and separate the solution. The filtration pressure is 0.1MPa, and the filtration precision of the filter material is 70μm. The filtration time is 10min. The resulting filtrate is clear, and the turbidity is measured to be 2.4NTU.

[0053] The above filtrate was post-processed to obtain cellulose acetate butyrate product. ICP-MS analysis showed that the sulfur content was 35 ppm and the metal Ca content was <10 ppm.

[0054] Example 4

[0055] 10g of MgCl₂·4H₂O was dissolved in 40g of water. After complete dissolution, 50g of montmorillonite was added, and the mixture was stirred for 2 hours. The solution was then dried in a rotary evaporator. The rotary evaporator was set to a temperature of 80℃ and a vacuum of 50kPa. The dried powder was placed in a tube furnace and calcined in air at 450℃ for 6 hours at an air flow rate of 30mL / min to obtain a heterogeneous neutralizing agent. EDX analysis showed that the MgO content in the heterogeneous neutralizing agent in this example was 0.53wt%, and the average particle size of the product was 187μm.

[0056] Take 10g of the heterogeneous neutralizing agent prepared above and add it to 1000g of cellulose acetate butyrate hydrolysis reaction solution. Stir and react at 60℃ for 1h, then filter and separate. The filtration pressure is 0.1MPa, and the filtration precision of the filter material is 80μm. The filtration time is 15min. The resulting filtrate is clear, and the turbidity is measured to be 2.9NTU.

[0057] The above filtrate was post-processed to obtain cellulose acetate butyrate product. ICP-MS analysis showed that the sulfur content was 39 ppm and the Mg content was <10 ppm.

[0058] Comparative Example 1

[0059] The cellulose acetate butyrate hydrolysis solution was neutralized using essentially the same method as in Example 1, except that the heterogeneous neutralizing agent was replaced with Mg(CH3COO)2·4H2O. After neutralization, the solution was filtered at a pressure of 0.3 MPa and a filter media with a filtration precision of 50 μm. The filtration time was 60 min, and the resulting filtrate was turbid, with a turbidity of 18 NTU.

[0060] The above filtrate was post-processed to obtain cellulose acetate butyrate product. ICP-MS analysis showed that the sulfur content was 234 ppm and the Mg content was 127 ppm.

[0061] Comparative Example 2

[0062] The cellulose acetate butyrate hydrolysis solution was neutralized using essentially the same method as in Example 1, except that the heterogeneous neutralizing agent was replaced with MgO. After neutralization, the solution was filtered and separated at a pressure of 0.3 MPa and a filtration precision of 50 μm. The filtration time was 72 min, and the resulting filtrate was turbid, with a measured turbidity of 34 NTU.

[0063] The above filtrate was post-processed to obtain cellulose acetate butyrate product. ICP-MS analysis showed that the sulfur content was 389 ppm and the Mg content was 198 ppm.

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. The application of a heterogeneous neutralizing agent in the preparation of cellulose acetate butyrate, characterized in that, A heterogeneous neutralizing agent was added to the cellulose acetate butyrate hydrolysis reaction solution, and after neutralization treatment, the solution was filtered to obtain the cellulose acetate butyrate neutralized reaction solution. The heterogeneous neutralizing agent is a metal oxide / carrier composite material; the metal oxide is at least one of MgO, ZnO, and CaO; the carrier is at least one of montmorillonite, kaolin, ZSM-5 molecular sieve, and UIO-66; the neutralization treatment conditions are: neutralization reaction at 40-60℃ for 0.2-1h; The composition of the cellulose acetate butyrate hydrolysis reaction solution includes: 10-30% cellulose acetate butyrate, 60-80% butyric acid, 1-10% acetic acid, 0.05-0.2% sulfuric acid, and 1-3% water, with the total mass of the above components being 100%.

2. The application according to claim 1, characterized in that, The content of the metal oxide in the composite material is 0.5-2 wt%.

3. The application according to claim 1, characterized in that, The amount of the heterogeneous neutralizing agent is 0.1-1% of the mass of the cellulose acetate butyrate hydrolysis reaction solution.

4. The application according to any one of claims 1-3, characterized in that, The filtration method is pressure filtration, with a pressure of 0.1-0.3 MPaG.

5. The application according to claim 4, characterized in that, The filtration material used has a filtration accuracy of 50-80μm.

6. The application according to any one of claims 1-3, characterized in that, The heterogeneous neutralizing agent is prepared by any one or more of the following methods: impregnation, deposition precipitation, ion exchange, and coprecipitation.

7. The application according to any one of claims 1-3, characterized in that, The average particle size of the heterogeneous neutralizing agent is 100-200 μm.