Method for removing NMP (N-Methyl Pyrrolidone) in poly-p-phenylene terephthamide resin

Abstract

The invention discloses a method for removing NMP (N-Methyl Pyrrolidone) in poly-p-phenylene terephthamide resin, and belongs to the technical field of organic matter separation. The particle size of the poly-p-phenylene terephthamide resin ground by the method is not greater than 0.2 mm, and the poly-p-phenylene terephthamide resin is easily dissolved in concentrated sulfuric acid, is easier to prepare poly-p-phenylene terephthamide resin slurry, is convenient to remove NMP, and enables the content of NMP in the poly-p-phenylene terephthamide resin to be not greater than 0.01%.

Description

Technical Field

[0001] This invention belongs to the field of organic matter separation technology, specifically relating to a method for removing NMP from poly(p-phenylene terephthalamide) resin. Background Technology

[0002] Para-aramid fiber, also known as poly(p-phenylene terephthalamide) fiber, is the most widely used and in-demand organic fiber among the three major high-performance fibers in the world today. Para-aramid is known in the materials industry as the "versatile material" because of its wide range of applications. It is the first choice for manufacturing high-strength lightweight armor and special protective materials, and is widely used in aerospace, aviation, military, electromechanical, construction, automotive, sporting goods and other fields.

[0003] The production of PPTA resin requires a large amount of NMP-containing composite solvent. Currently, most methods for preparing this composite solvent involve adding CaCl2 solid powder to NMP solvent, followed by dehydration to obtain the composite solvent, forming an organic solvent system with NMP as the solvent and calcium chloride as a co-solvent. However, the PPTA resin particles produced by this solvent system are relatively large, inevitably containing some NMP encapsulation. While the PPTA resin washing process can remove NMP from the external surface and adhering to the resin, it cannot remove NMP encapsulated within the resin. This NMP-containing resin will darken the color of the PPTA slurry during subsequent spinning and sizing stages, and may even affect the strength and stability of the yarn. How to remove NMP from the resin to the greatest extent possible has become a major challenge in the industry. Summary of the Invention

[0004] The purpose of this invention is to provide a method for removing NMP from poly(p-phenylene terephthalamide) resin. The poly(p-phenylene terephthalamide) resin after grinding by this method has a particle size of no more than 0.2 mm, is easily soluble in concentrated sulfuric acid, and is easier to prepare into poly(p-phenylene terephthalamide) resin slurry, which facilitates the removal of NMP and ensures that the NMP content in the poly(p-phenylene terephthalamide) resin is no more than 0.01%.

[0005] This invention is achieved through the following technical solution:

[0006] A method for removing NMP from poly(p-phenylene terephthalamide) resin, comprising the following steps:

[0007] S1. After mixing zirconium dioxide and poly(p-phenylene terephthalamide) resin at a volume ratio of 1:1-2, the mixture is placed in a zirconium dioxide grinder for grinding.

[0008] S2. The ground zirconium dioxide and poly(p-phenylene terephthalamide) resin are separated using a separation device;

[0009] S3. The poly(p-phenylene terephthalamide) resin obtained after separation is placed in a stirring and cleaning device for cleaning treatment.

[0010] S4. The cleaned poly(p-phenylene terephthalamide) resin is subjected to a second cleaning and dehydration treatment. The water after cleaning enters the solvent recovery system, thus completing the process.

[0011] Preferably, in S1, the water content of the poly(p-phenylene terephthalamide) resin is not less than 5-50 wt%, and preferably 10 wt%.

[0012] In the aforementioned removal method, grinding must precede subsequent steps. The purpose of grinding is to use zirconium dioxide to reduce the poly(p-phenylene terephthalamide) resin to a particle size of no more than 0.2 mm, preferably 0.1 mm, thereby increasing the contact area between the poly(p-phenylene terephthalamide) resin particles and the cleaning solvent, and thus increasing the amount of NMP leached out. Without grinding, the poly(p-phenylene terephthalamide) resin particles are larger, making it difficult for NMP to be leached out.

[0013] Preferably, in S1, the particle size of the poly(p-phenylene terephthalamide) resin is 0.2-1 mm.

[0014] Preferably, in S1, the diameter of the zirconium dioxide is 0.8-1.2 mm, and more preferably 0.8 mm.

[0015] Preferably, in step S1, the grinding time of zirconium dioxide and poly(p-phenylene terephthalamide) resin is 0.5-4 hours, preferably 2 hours.

[0016] Preferably, in step S2, the particle size of the poly(p-phenylene terephthalamide) resin after grinding is not greater than 0.2 mm, and more preferably 0.1 mm.

[0017] Preferably, in step S2, the separation device is a vibrating screen;

[0018] The sieve aperture diameter of the separation device is 0.4-0.6 mm, preferably 0.5 mm.

[0019] Preferably, in step S3, the cleaning device is a stirred tank through which deionized water is introduced;

[0020] During the cleaning process, the temperature of the deionized water is 40-100℃, and the volume of the deionized water is 1 / 4-1 / 3 of the volume of the mixing tank; the volume of the poly(p-phenylene terephthalamide) resin being cleaned is 1 / 4-1 / 3 of the volume of the mixing tank.

[0021] The cleaning time of the poly(p-phenylene terephthalamide) resin is 0.5-4 hours, preferably 2 hours.

[0022] The above method uses only water for cleaning because NMP is miscible with water. However, since the interior of poly(p-phenylene terephthalamide) resin particles is not easy to clean, it is necessary to use water at 40-100°C for cleaning. Stirring with hot water will further promote the cleaning effect of NMP.

[0023] Preferably, in step S4, the secondary cleaning and dehydration are performed using a centrifuge; the secondary cleaning is performed using a spray cleaning method.

[0024] The NMP content in the dehydrated poly(p-phenylene terephthalamide) resin is not higher than 0.01%, preferably 0.005%.

[0025] The purpose of performing the second cleaning is to further improve the cleaning effect of NMP.

[0026] Preferably, in step S4, the water content of the dehydrated poly(p-phenylene terephthalamide) resin is not higher than 1%, and preferably 0.2%.

[0027] Compared with the prior art, the present invention has at least the following technical effects:

[0028] This invention provides a method for removing NMP from poly(p-phenylene terephthalamide) resin. The poly(p-phenylene terephthalamide) resin after grinding by this method has a particle size of no more than 0.2 mm. It is easily soluble in concentrated sulfuric acid and easier to prepare poly(p-phenylene terephthalamide) resin slurry, which facilitates the removal of NMP and ensures that the NMP content in the poly(p-phenylene terephthalamide) resin is no more than 0.01%. Detailed Implementation

[0029] The embodiments of the present invention will be described in detail below with reference to the examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Specific conditions not specified in the examples shall be carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0030] One specific embodiment of the present invention is as follows:

[0031] A method for removing NMP from poly(p-phenylene terephthalamide) resin, comprising the following steps:

[0032] S1. After mixing zirconium dioxide and poly(p-phenylene terephthalamide) resin at a volume ratio of 1:1-2, the mixture is placed in a zirconium dioxide grinder for grinding.

[0033] S2. The ground zirconium dioxide and poly(p-phenylene terephthalamide) resin are separated using a separation device;

[0034] S3. The poly(p-phenylene terephthalamide) resin obtained after separation is placed in a stirring and cleaning device for cleaning treatment.

[0035] S4. The cleaned poly(p-phenylene terephthalamide) resin is subjected to a second cleaning and dehydration treatment. The water after cleaning enters the solvent recovery system, thus completing the process.

[0036] Preferably, in S1, the water content of the poly(p-phenylene terephthalamide) resin is not less than 5-50 wt%, and preferably 10 wt%.

[0037] Preferably, in S1, the particle size of the poly(p-phenylene terephthalamide) resin is 0.2-1 mm.

[0038] Preferably, in S1, the diameter of the zirconium dioxide is 0.8-1.2 mm, and more preferably 0.8 mm.

[0039] Preferably, in step S1, the grinding time of zirconium dioxide and poly(p-phenylene terephthalamide) resin is 0.5-4 hours, preferably 2 hours.

[0040] Preferably, in step S2, the particle size of the poly(p-phenylene terephthalamide) resin after grinding is not greater than 0.2 mm, and more preferably 0.1 mm.

[0041] Preferably, in step S2, the separation device is a vibrating screen;

[0042] The sieve aperture diameter of the separation device is 0.4-0.6 mm, preferably 0.5 mm.

[0043] Preferably, in step S3, the cleaning device is a stirred tank through which deionized water is introduced;

[0044] During the cleaning process, the temperature of the deionized water is 40-100℃, and the volume of the deionized water is 1 / 4-1 / 3 of the volume of the mixing tank; the volume of the poly(p-phenylene terephthalamide) resin being cleaned is 1 / 4-1 / 3 of the volume of the mixing tank.

[0045] The cleaning time of the poly(p-phenylene terephthalamide) resin is 0.5-4 hours, preferably 2 hours.

[0046] Preferably, in step S4, the secondary cleaning and dehydration are performed using a centrifuge; the secondary cleaning is performed using a spray cleaning method.

[0047] The NMP content in the dehydrated poly(p-phenylene terephthalamide) resin is not higher than 0.01%, preferably 0.005%.

[0048] Preferably, in step S4, the water content of the dehydrated poly(p-phenylene terephthalamide) resin is not higher than 1%, and preferably 0.2%.

[0049] Example 1:

[0050] A method for removing NMP from poly(p-phenylene terephthalamide) resin, comprising the following steps:

[0051] S1. After mixing zirconium dioxide and poly(p-phenylene terephthalamide) resin at a volume ratio of 1:2, the mixture is placed in a zirconium dioxide grinder for grinding.

[0052] S2. The ground zirconium dioxide and poly(p-phenylene terephthalamide) resin are separated using a separation device;

[0053] S3. The poly(p-phenylene terephthalamide) resin obtained after separation is placed in a stirring and cleaning device for cleaning treatment.

[0054] S4. The cleaned poly(p-phenylene terephthalamide) resin is subjected to a second cleaning and dehydration treatment. The water after cleaning enters the solvent recovery system, thus completing the process.

[0055] In S1, the water content of the poly(p-phenylene terephthalamide) resin is not less than 10 wt%.

[0056] In S1, the particle size of the poly(p-phenylene terephthalamide) resin is 1 mm.

[0057] In S1, the zirconium dioxide has a diameter of 0.8 mm.

[0058] In S1, the grinding time of zirconium dioxide and poly(p-phenylene terephthalamide) resin is 2 hours.

[0059] In step S2, the particle size of the poly(p-phenylene terephthalamide) resin after grinding is no greater than 0.1 mm.

[0060] In S2, the separation device is a vibrating screen;

[0061] The sieve aperture diameter of the separation device is 0.5 mm.

[0062] In S3, the cleaning device is a stirred tank through which deionized water is introduced;

[0063] During the cleaning process, the temperature of the deionized water is 100°C, and the volume of the deionized water is 1 / 4 to 1 / 3 of the volume of the mixing tank; the volume of the poly(p-phenylene terephthalamide) resin being cleaned is 1 / 4 to 1 / 3 of the volume of the mixing tank.

[0064] The cleaning time for the poly(p-phenylene terephthalamide) resin is 2 hours.

[0065] In step S4, the secondary cleaning and dehydration are performed using a centrifuge; the secondary cleaning is performed using a spray cleaning method.

[0066] The NMP content in the dehydrated poly(p-phenylene terephthalamide) resin is not higher than 0.005%.

[0067] In step S4, the water content of the dehydrated poly(p-phenylene terephthalamide) resin is not higher than 0.2%.

[0068] Example 2:

[0069] A method for removing NMP from poly(p-phenylene terephthalamide) resin, comprising the following steps:

[0070] S1. After mixing zirconium dioxide and poly(p-phenylene terephthalamide) resin at a volume ratio of 1:1, the mixture is placed in a zirconium dioxide grinder for grinding.

[0071] S2. The ground zirconium dioxide and poly(p-phenylene terephthalamide) resin are separated using a separation device;

[0072] S3. The poly(p-phenylene terephthalamide) resin obtained after separation is placed in a stirring and cleaning device for cleaning treatment.

[0073] S4. The cleaned poly(p-phenylene terephthalamide) resin is subjected to a second cleaning and dehydration treatment. The water after cleaning enters the solvent recovery system, thus completing the process.

[0074] Preferably, in S1, the water content of the poly(p-phenylene terephthalamide) resin is not less than 5 wt%.

[0075] In S1, the particle size of the poly(p-phenylene terephthalamide) resin is 0.2 mm.

[0076] In S1, the zirconium dioxide has a diameter of 1.2 mm.

[0077] In S1, the grinding time of zirconium dioxide and poly(p-phenylene terephthalamide) resin is 0.5 h.

[0078] In step S2, the particle size of the poly(p-phenylene terephthalamide) resin after grinding is no greater than 0.2 mm.

[0079] In S2, the separation device is a vibrating screen;

[0080] The sieve aperture diameter of the separation device is 0.4 mm.

[0081] In S3, the cleaning device is a stirred tank through which deionized water is introduced;

[0082] During the cleaning process, the temperature of the deionized water is 40°C, and the volume of the deionized water is 1 / 4 to 1 / 3 of the volume of the mixing tank; the volume of the poly(p-phenylene terephthalamide) resin being cleaned is 1 / 4 to 1 / 3 of the volume of the mixing tank.

[0083] The cleaning time of the poly(p-phenylene terephthalamide) resin is 4 hours.

[0084] In step S4, the secondary cleaning and dehydration are performed using a centrifuge; the secondary cleaning is performed using a spray cleaning method.

[0085] The NMP content in the dehydrated poly(p-phenylene terephthalamide) resin is no higher than 0.01%.

[0086] In step S4, the water content of the dehydrated poly(p-phenylene terephthalamide) resin is not higher than 1%.

[0087] Example 3:

[0088] A method for removing NMP from poly(p-phenylene terephthalamide) resin, comprising the following steps:

[0089] S1. After mixing zirconium dioxide and poly(p-phenylene terephthalamide) resin at a volume ratio of 1:2, the mixture is placed in a zirconium dioxide grinder for grinding.

[0090] S2. The ground zirconium dioxide and poly(p-phenylene terephthalamide) resin are separated using a separation device;

[0091] S3. The poly(p-phenylene terephthalamide) resin obtained after separation is placed in a stirring and cleaning device for cleaning treatment.

[0092] S4. The cleaned poly(p-phenylene terephthalamide) resin is subjected to a second cleaning and dehydration treatment. The water after cleaning enters the solvent recovery system, thus completing the process.

[0093] In S1, the water content of the poly(p-phenylene terephthalamide) resin is not less than 50 wt%.

[0094] In S1, the particle size of the poly(p-phenylene terephthalamide) resin is 1 mm.

[0095] In S1, the zirconium dioxide has a diameter of 0.8 mm.

[0096] In S1, the grinding time of zirconium dioxide and poly(p-phenylene terephthalamide) resin is 4 hours.

[0097] In step S2, the particle size of the poly(p-phenylene terephthalamide) resin after grinding is no greater than 0.1 mm.

[0098] In S2, the separation device is a vibrating screen;

[0099] The sieve diameter of the separation device is 0.6 mm.

[0100] In S3, the cleaning device is a stirred tank through which deionized water is introduced;

[0101] During the cleaning process, the temperature of the deionized water is 100°C, and the volume of the deionized water is 1 / 4 to 1 / 3 of the volume of the mixing tank; the volume of the poly(p-phenylene terephthalamide) resin being cleaned is 1 / 4 to 1 / 3 of the volume of the mixing tank.

[0102] The cleaning time of the poly(p-phenylene terephthalamide) resin is 0.5 h.

[0103] In step S4, the secondary cleaning and dehydration are performed using a centrifuge; the secondary cleaning is performed using a spray cleaning method.

[0104] The NMP content in the dehydrated poly(p-phenylene terephthalamide) resin is not higher than 0.005%.

[0105] In step S4, the water content of the dehydrated poly(p-phenylene terephthalamide) resin is not higher than 0.2%.

[0106] Comparative Example 1: Based on Example 1, the particle size of the poly(p-phenylene terephthalamide) resin was 0.2 mm, and all other parameters remained unchanged.

[0107] Comparative Example 2: Based on Example 1, the particle size of the poly(p-phenylene terephthalamide) resin was 0.1 mm, and other parameters remained unchanged.

[0108] Particle size of poly(p-phenylene terephthalamide) resin NMP content (%) after treatment Example 1 1mm 0.005 Comparative Example 1 0.2mm 0.005 Comparative Example 2 0.1mm 0.005

[0109] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for removing NMP from poly(p-phenylene terephthalamide) resin, characterized in that, Includes the following steps: S1. After mixing zirconium dioxide and poly(p-phenylene terephthalamide) resin at a volume ratio of 1:1-2, the mixture is placed in a zirconium dioxide grinder for grinding. S2. The ground zirconium dioxide and poly(p-phenylene terephthalamide) resin are separated using a separation device; S3. The poly(p-phenylene terephthalamide) resin obtained after separation is placed in a stirring and cleaning device for cleaning treatment. S4. The cleaned poly(p-phenylene terephthalamide) resin is subjected to a second cleaning and dehydration treatment. The water after cleaning enters the solvent recovery system, thus completing the process.

2. The method for removing NMP from poly(p-phenylene terephthalamide) resin according to claim 1, characterized in that, In S1, the water content of the poly(p-phenylene terephthalamide) resin is not less than 5-50 wt%, preferably 10 wt%.

3. The method for removing NMP from poly(p-phenylene terephthalamide) resin according to claim 1, characterized in that, In S1, the particle size of the poly(p-phenylene terephthalamide) resin is 0.2-1 mm.

4. The method for removing NMP from poly(p-phenylene terephthalamide) resin according to claim 1, characterized in that, In S1, the diameter of zirconium dioxide is 0.8-1.2 mm, preferably 0.8 mm.

5. The method for removing NMP from poly(p-phenylene terephthalamide) resin according to claim 1, characterized in that, In step S1, the grinding time of zirconium dioxide and poly(p-phenylene terephthalamide) resin is 0.5-4 hours, preferably 2 hours.

6. The method for removing NMP from poly(p-phenylene terephthalamide) resin according to claim 1, characterized in that, In step S2, the particle size of the poly(p-phenylene terephthalamide) resin after grinding is no greater than 0.2 mm, preferably 0.1 mm.

7. The method for removing NMP from poly(p-phenylene terephthalamide) resin according to claim 1, characterized in that, In S2, the separation device is a vibrating screen; The sieve aperture diameter of the separation device is 0.4-0.6 mm, preferably 0.5 mm.

8. The method for removing NMP from poly(p-phenylene terephthalamide) resin according to claim 1, characterized in that, In S3, the cleaning device is a stirred tank through which deionized water is introduced; During the cleaning process, the temperature of the deionized water is 40-100℃, and the volume of the deionized water is 1 / 4-1 / 3 of the volume of the mixing tank; the volume of the poly(p-phenylene terephthalamide) resin being cleaned is 1 / 4-1 / 3 of the volume of the mixing tank; the cleaning time of the poly(p-phenylene terephthalamide) resin is 0.5-4 hours, preferably 2 hours.

9. The method for removing NMP from poly(p-phenylene terephthalamide) resin according to claim 1, characterized in that, In step S4, the secondary washing and dehydration are performed using a centrifuge; The secondary cleaning is performed using a spray cleaning method; The NMP content in the dehydrated poly(p-phenylene terephthalamide) resin is not higher than 0.01%, preferably 0.005%.

10. The method for removing NMP from poly(p-phenylene terephthalamide) resin according to claim 1, characterized in that, In step S4, the water content of the dehydrated poly(p-phenylene terephthalamide) resin is not higher than 1%, preferably 0.2%.