Recovery method of auxiliary agent in resin production

Abstract

The invention provides a method for recovering auxiliaries in resin production, and relates to the field of resin production. The method comprises the following steps: S1, carbonizing and degrading an organic matter: carrying out pyrolytic reaction on byproduct salt containing an auxiliary agent and the organic matter, and converting the organic matter into carbon black; s2, extracting an auxiliary agent: transferring the byproduct salt treated in the step S1 into an extraction kettle, adding N-methyl pyrrolidone, and extracting for 1-2 hours; s3, solid-liquid separation is conducted through a centrifugal machine, an N-methyl pyrrolidone extraction solution containing the auxiliaries is obtained, and the N-methyl pyrrolidone extraction solution is used for resin preparation. The solvent N-methyl pyrrolidone required to be used in the resin production process is used as the extraction agent, and the additive is dissolved in the extraction agent by adding extraction, so that the additive is recycled, the resin production cost can be reduced, and the method is green and environment-friendly.

Description

Technical Field

[0001] The invention relates to the technical field of resin production, and in particular to a method for recovering auxiliary agents in resin production. Background Art

[0002] In the production of resin, NMP is used as solvent, metal halide (such as lithium chloride) is used as auxiliary agent or other auxiliary agents soluble in NMP, etc., and resin is generated through polycondensation reaction; the resin polymerization product is in the form of solid-liquid slurry, and its main components include: resin, metal halide auxiliary agent (such as lithium chloride) or other auxiliary agents soluble in NMP, by-product salt, NMP, etc. In the production process of resin, the consumption and recovery of auxiliary agents have always been a concern. The recovery of auxiliary agents can not only reduce costs and reduce resource waste, but also reduce environmental pollution and achieve green production.

[0003] At present, the main methods for recovering the auxiliary agent lithium chloride in the resin production process are:

[0004] Chemical recovery includes steps such as dissolution, separation and purification; lithium chloride is made to exist in the form of ions, and then separated from the solution by ion exchange, precipitation, extraction and other methods. The separated lithium chloride needs to be further purified to meet the needs of subsequent production.

[0005] Physical recovery includes evaporation crystallization, membrane separation and other technologies. The evaporation crystallization method heats the waste liquid to evaporate the water, and the lithium chloride is gradually concentrated and crystallized. The membrane separation method uses membrane materials with specific properties to selectively separate ions in the solution, thereby realizing the recovery of lithium chloride.

[0006] Resin adsorption uses resins with specific adsorption properties to adsorb and remove impurity ions in the solution, thereby improving the purity of lithium chloride.

[0007] However, the above-mentioned recycling methods all have problems such as high production cost and complicated process, and cannot be directly applied to the resin production process. Summary of the invention

[0008] The purpose of the present invention is to provide a method for recovering auxiliary agents in resin production, which utilizes N-methylpyrrolidone, a solvent required to be used in the resin production process, as an extractant, and dissolves the auxiliary agent in the extractant by adding an extraction method to achieve the recovery of the auxiliary agent, and finally obtains a mixed solution of the auxiliary agent and the extractant, which can be directly reused in the resin production process, can effectively reduce the cost in the resin production process, and is green and environmentally friendly.

[0009] The present invention solves the technical problem by adopting the following technical solutions.

[0010] The embodiment of the present invention provides a method for recovering an additive in resin production, comprising the following steps: S1, carbonizing and degrading organic matter: subjecting a byproduct salt containing an additive and organic matter to a pyrolysis reaction to convert the organic matter into carbon black;

[0011] S2, extraction aid: transfer the by-product salt after the treatment in step S1 into an extraction kettle, add N-methylpyrrolidone, and extract for 1-2 hours;

[0012] S3, separating solid and liquid by centrifuge to obtain an N-methylpyrrolidone extraction solution containing an additive, and using the N-methylpyrrolidone extraction solution for resin preparation.

[0013] In some embodiments of the present invention, in step S1, the temperature of the pyrolysis reaction is 400-600°C.

[0014] In some embodiments of the present invention, in step S1, the volume of by-product salt in the extraction kettle: the volume of N-methylpyrrolidone = 1:3-5.

[0015] In some embodiments of the present invention, in step S1, the volume of by-product salt in the extraction kettle: the volume of N-methylpyrrolidone = 1:5.

[0016] In some embodiments of the present invention, in step S2, the extraction temperature is 70-90°C.

[0017] In some embodiments of the present invention, in step S2, the extraction temperature is 90°C.

[0018] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0019] The auxiliary agent recovery method provided in the embodiment of the present invention utilizes N-methylpyrrolidone, a solvent required for use in the resin production process, as an extractant, and dissolves the auxiliary agent in the extractant by adding an extraction method to achieve auxiliary agent recovery, and finally obtains a mixed solution of the auxiliary agent and the extractant, which can be directly reused in the resin production process, can effectively reduce the cost of the resin production process, and is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 This is a process diagram for recovering additives according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0023] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to specific embodiments.

[0024] The embodiment of the present invention provides a method for recovering an additive in resin production, comprising the following steps: S1, carbonizing and degrading organic matter: subjecting a byproduct salt containing an additive and organic matter to a pyrolysis reaction to convert the organic matter into carbon black;

[0025] S2, extraction aid: transfer the by-product salt after the treatment in step S1 into an extraction kettle, add N-methylpyrrolidone, and extract for 1-2 hours;

[0026] S3, separating solid and liquid by centrifuge to obtain an N-methylpyrrolidone extraction solution containing an additive, and using the N-methylpyrrolidone extraction solution for resin preparation.

[0027] Specifically, in the resin production process, by-product salts containing organic matter such as lithium chloride additives and carboxylates are produced. The by-product salts are first thermally decomposed at high temperature to convert the organic matter into carbon black, thereby reducing the organic matter concentration of the by-product salts and facilitating subsequent extraction. N-methylpyrrolidone is then added to the by-product salts as an extractant. The solubility of the lithium chloride additive in N-methylpyrrolidone is high, and its solubility increases accordingly as the temperature rises; and the solubility of other components in the by-product salts (such as sodium chloride) in N-methylpyrrolidone is different from that of the lithium chloride additive, so that the lithium chloride additive can be extracted. When preparing PPS resin, N-methylpyrrolidone is also used as a solvent. Therefore, after solid-liquid separation in step S3, the N-methylpyrrolidone mixed solution containing lithium chloride and other additives soluble in N-methylpyrrolidone can be directly reused in the PPS resin preparation process, without the need to separate the additives and N-methylpyrrolidone, and the recovery process is simple.

[0028] In some embodiments of the present invention, in step S1, the temperature of the pyrolysis reaction is 400-600° C. At this temperature, organic substances such as carboxylates in the by-product salt can be decomposed and converted into carbon black, which is insoluble in the extractant N-methylpyrrolidone. The carbon black in the by-product salt can be removed by solid-liquid separation and other methods, which is convenient for the subsequent extraction of lithium chloride and other auxiliary agents soluble in N-methylpyrrolidone, and can ensure the purity of lithium chloride in the extractant and prevent other impurities from entering the N-methylpyrrolidone extractant.

[0029] In some embodiments of the present invention, in step S1, the volume of by-product salt in the extraction kettle: the volume of N-methylpyrrolidone = 1:3-5. In the actual production process, adding 3-5 times the volume of the extractant to the by-product salt after thermal decomposition can fully dissolve the lithium chloride and other auxiliary agents soluble in N-methylpyrrolidone in the by-product salt, improve the extraction efficiency, and be able to extract more lithium chloride and other auxiliary agents soluble in N-methylpyrrolidone in the by-product salt.

[0030] In some embodiments of the present invention, in step S1, the volume of by-product salt in the extraction kettle: the volume of N-methylpyrrolidone = 1:5.

[0031] In some embodiments of the present invention, in step S2, the extraction temperature is 70-90° C. When the extraction is performed at this temperature range, the solubility of lithium chloride in the N-methylpyrrolidone extractant is high, while the solubility of other impurities is low, so as to ensure the extraction rate and purity.

[0032] In some embodiments of the present invention, in step S2, the extraction temperature is 90°C.

[0033] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0034] Example 1

[0035] Add 5g lithium chloride and 20g sodium chloride to a beaker, add water to completely dissolve; evaporate and crystallize, dry; then add 100g NMP, stir and heat to 70°C, extract for 2h, and detect the lithium chloride concentration of the extract. The lithium chloride input concentration is 4.76%, the lithium chloride content in the extract is 4.32%, and the recycling rate is 90.8%.

[0036] Example 2

[0037] Add 5g lithium chloride and 20g sodium chloride to a beaker, add water to completely dissolve; evaporate and crystallize, dry; then add 75g NMP, stir and heat to 90°C, extract for 1h, and detect the lithium chloride concentration of the extract. The lithium chloride input concentration is 6.25%, the lithium chloride content in the extract is 5.71%, and the recycling rate is 91.2%.

[0038] Example 3

[0039] Take the by-product salt produced during the preparation of PPS resin as the auxiliary agent recovery object, and perform auxiliary agent recovery according to the following steps:

[0040] S1: The by-product salt (high TOC) containing organic matter such as additives and carboxylates is pyrolyzed and carbonized at 600°C, and the organic matter in the by-product salt is converted into carbon black, etc., thereby reducing the TOC of the by-product salt.

[0041] S2: The treated by-product salt is transferred to an extraction kettle, 5 volumes of N-methylpyrrolidone (mass concentration ≥ 99%) are added, and the mixture is heated to 90°C with stirring and extracted for 2 hours;

[0042] S3, placing the by-product salt system after extraction in a centrifuge for solid-liquid separation to obtain an N-methylpyrrolidone extraction solution containing an additive, and then the N-methylpyrrolidone extraction solution containing an additive will be used in the PPS resin preparation process.

[0043] Example 4

[0044] Take the by-product salt produced in the same PPS resin preparation process as in Example 3 as the auxiliary agent recovery object, and perform auxiliary agent recovery according to the following steps:

[0045] S1: The by-product salt (high TOC) containing organic matter such as additives and carboxylates is pyrolyzed and carbonized at 600°C, and the organic matter in the by-product salt is converted into carbon black, etc., thereby reducing the TOC of the by-product salt.

[0046] S2: Transfer the treated by-product salt into an extraction kettle, add 3 volumes of N-methylpyrrolidone (mass concentration ≥ 99%), stir and heat to 90°C, and extract for 1 hour;

[0047] S3, placing the by-product salt system after extraction in a centrifuge for solid-liquid separation to obtain an N-methylpyrrolidone extraction solution containing an additive, and then the N-methylpyrrolidone extraction solution containing an additive will be used in the PPS resin preparation process.

[0048] Example 5

[0049] Take the by-product salt produced in the same PPS resin preparation process as in Example 3 as the auxiliary agent recovery object, and perform auxiliary agent recovery according to the following steps:

[0050] S1: The by-product salt (high TOC) containing organic matter such as additives and carboxylates is pyrolyzed and carbonized at 400°C, and the organic matter in the by-product salt is converted into carbon black, etc., thereby reducing the TOC of the by-product salt.

[0051] S2: Transfer the treated by-product salt into an extraction kettle, add 5 volumes of N-methylpyrrolidone (mass concentration ≥ 99%), stir and heat to 70°C, and extract for 5 hours;

[0052] S3, placing the by-product salt system after extraction in a centrifuge for solid-liquid separation to obtain an N-methylpyrrolidone extraction solution containing an additive, and then the N-methylpyrrolidone extraction solution containing an additive will be used in the PPS resin preparation process.

[0053] In summary, the method for recovering an auxiliary agent provided in an embodiment of the present invention utilizes N-methylpyrrolidone, a solvent required for use in the resin production process, as an extractant, and dissolves the auxiliary agent in the extractant by adding an extractor to achieve the recovery of the auxiliary agent, and finally obtains a mixed solution of the auxiliary agent and the extractant, which can be directly reused in the resin production process, can effectively reduce the cost of the resin production process, and is green and environmentally friendly.

[0054] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for recovering an auxiliary agent in resin production, characterized in that: The following steps are involved: S1, carbonization degradation of organic matter: pyrolysis of by-product salts containing additives and organic matter to convert organic matter into carbon black; S2, extraction aid: transfer the by-product salt after the treatment in step S1 into an extraction kettle, add N-methylpyrrolidone, and extract for 1-2 hours; S3, separating solid and liquid by centrifuge to obtain an N-methylpyrrolidone extraction solution containing an additive, and using the N-methylpyrrolidone extraction solution for resin preparation.

2. The method for recovering auxiliary agents in resin production according to claim 1, characterized in that: In step S1, the temperature of the pyrolysis reaction is 400-600°C.

3. The method for recovering auxiliary agents in resin production according to claim 1, characterized in that: In the step S1, the volume of by-product salt in the extraction kettle: the volume of N-methylpyrrolidone = 1:3-5.

4. The method for recovering auxiliary agents in resin production according to claim 3, characterized in that: In the step S1, the volume of by-product salt in the extraction kettle: the volume of N-methylpyrrolidone = 1:

5.

5. The method for recovering auxiliary agents in resin production according to claim 1, characterized in that: In step S2, the extraction temperature is 70-90°C.

6. The method for recovering auxiliary agents in resin production according to claim 5, characterized in that: In step S2, the extraction temperature is 90°C.

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