Purification method of polyphenylene sulfide

Abstract

The invention provides a purification method of crude polyphenylene sulfide, which comprises the following steps: (1) adding a polyphenylene sulfide resin crude product into an organic solvent, heating, stirring, filtering, and collecting a filtrate; (2) adding deionized water and a washing assistant, heating and stirring, filtering, and collecting a filtrate; (3) adding deionized water, heating, stirring, filtering, and collecting a filtered substance; and (4) adding a low-boiling-point alcohol solvent, stirring, washing, filtering and drying at room temperature to obtain a final polyphenylene sulfide product. In the washing process, the temperature of a molecular chain segment is higher than the glass-transition temperature, so that the salinity in the polyphenylene sulfide resin can be remarkably reduced; the surfactant is adopted to effectively reduce the content of inorganic salt in the product, and the low-boiling-point alcohol is adopted to remarkably reduce the moisture and volatile components in the product, so that the drying temperature of the product is reduced, and thermal oxidation crosslinking of the product in the drying process is avoided; by adding the surfactant, the compatibility of the detergent and residual organic matters can be improved, the purification effect is enhanced, and the content of volatile components is reduced.

Description

Technical Field

[0001] The invention belongs to the field of chemical synthesis and purification, and in particular relates to a method for purifying crude benzene sulfide. Background Art

[0002] Polyphenylene sulfide resin (PPS) is an engineering plastic with excellent comprehensive performance. It has excellent mechanical properties, high temperature resistance, acid and alkali corrosion resistance, flame retardancy, excellent electrical properties and processing performance. It can be made into composite materials such as fibers, coatings, and films. It is widely used in electronics, automobiles, machinery, chemicals and other fields.

[0003] The synthesis method of polyphenylene sulfide resin currently mainly adopts the sodium sulfide method. The steps of this method are to mix polar organic solvent and sodium sulfide with p-dichlorobenzene under alkaline conditions, and perform polymerization reaction under high temperature and high pressure to finally obtain polyphenylene sulfide resin. This method has the advantages of easy availability of raw materials, mature process and low cost, so it is the current mainstream synthesis method. However, the polyphenylene sulfide resin synthesized by this method often contains salt impurities such as sodium chloride, which will have an adverse effect on the performance of the resin, especially the electrical properties. Therefore, the synthesized resin needs to be purified and washed before application. At present, the common washing methods for removing sodium chloride from the resin include multiple water washing or water washing combined with organic solvent washing. However, practice shows that these washing methods have several problems. First, the washing effect is not obvious enough, and the salt impurities in the resin cannot be completely removed. Secondly, some organic solvent washing methods have the problem of high toxicity. In addition, the method of multiple water washing or water washing combined with organic solvent washing has many washing times, high energy consumption, and correspondingly increased costs.

[0004] CN104817696A discloses a method for desalting and purifying a polymer product in the production of polyphenylene sulfide, and specifically discloses that after the polymerization reaction is completed, the mixture in the reaction system is filtered and separated, and the separated product is acid-washed, ultrasonically washed, washed with water, and then dried to obtain a purified product. This method can significantly reduce the content of inorganic salts in the polyphenylene sulfide product, improve and enhance the quality and performance of the PPS product, but the separation steps are cumbersome, the product loss is large, and the energy consumption is high.

[0005] CN107880266A discloses an ultrasonic cleaning and purification method for polyphenylene sulfide, which specifically includes: high-frequency ultrasonic pre-cleaning, ultrasonic low-frequency cleaning and purification, and vacuum drying. The method can effectively separate the crude polyphenylene sulfide, and the molecular weight distribution of the separated finished product is narrow, and the separation and purification effect is good, but the high-frequency and low-frequency ultrasonic cleaning are used twice, which has high requirements on equipment and high energy consumption, and cannot effectively remove the organic volatiles in the product.

[0006] Therefore, for the removal of salt impurities in polyphenylene sulfide resin, it is necessary to study and explore more effective, environmentally friendly and low-cost washing methods to meet the needs of industrial production. Summary of the invention

[0007] The technical problem to be solved by the present invention is that the current polyphenylene sulfide purification method is not effective, the resin impurities, especially oligomers and inorganic salt residues are high, and the commonly used solvents are costly and highly toxic. Therefore, the present invention proposes a polyphenylene sulfide resin purification process, which can efficiently remove salts and volatiles in the resin, optimize the purity of the resin, facilitate the subsequent processing of the resin, and is more environmentally friendly.

[0008] According to one aspect of the present invention, an object of the present invention is to provide a method for purifying polyphenylene sulfide resin, which can effectively remove the salt content and moisture in the polyphenylene sulfide resin, comprising the following steps:

[0009] (1) adding a crude polyphenylene sulfide resin into an organic solvent, heating and stirring at a certain temperature, filtering, and collecting the filtrate;

[0010] (2) adding deionized water and a detergent aid to the filtrate obtained in step (1), heating and stirring at a certain temperature, filtering, and collecting the filtrate;

[0011] (3) adding deionized water to the filtrate obtained in step (2), heating and stirring at a certain temperature, filtering, and collecting the filtrate.

[0012] (4) adding a low-boiling point alcohol solvent to the filtrate obtained in step (3), stirring and washing at room temperature, filtering, and drying to obtain a final polyphenylene sulfide product.

[0013] Preferably, in step (1), the mass ratio of the polyphenylene sulfide resin to the organic solvent is 1:(1-5), more preferably 1:(2-3).

[0014] Preferably, the organic solvent in step (1) includes, but is not limited to, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, hexamethylphosphoramide, 1,3-dimethylimidazolidinone, nitrogen-containing organic compounds, sulfoxide-sulfone solvents, ether solvents, halogen-based solvents, and phenolic solvents.

[0015] Further preferably, the nitrogen-containing organic compound is selected from 2-piperazinone; the sulfoxide-sulfone solvent is selected from dimethyl sulfone, dimethyl sulfoxide, etc.; the ketone solvent is selected from acetone, methyl ethyl ketone, acetophenone, etc.; the ether solvent is selected from dimethyl ether, dioxane, tetrahydrofuran, etc.; the halogen-based solvent is selected from chloroform, dichloromethane, trichloroethylene, dichloroethane, perchloroethylene, monochloroethane, dichloroethane, tetrachloroethane, perchloroethane, chlorobenzene, etc.; the phenol solvent is selected from phenol, cresol, etc.

[0016] Preferably, the stirring time in step (1), step (2), step (3) and step (4) is 2-6 hours.

[0017] Preferably, the stirring rate in step (1), step (2), step (3) and step (4) is 200 rpm.

[0018] Preferably, the washing temperature in step (1) is 100-210°C.

[0019] Preferably, the mass ratio of polyphenylene sulfide to water in step (2) is 1:(3-10), more preferably 1:(5-8).

[0020] Preferably, the washing temperature in step (2) is 100-200°C.

[0021] Preferably, the washing aid in step (2) is a surfactant.

[0022] Further preferably, the surfactant can be selected from one or more combinations of sodium lauryl ether sulfate, sodium lauryl sulfate, sodium stearate, sodium acetate, etc., more preferably sodium lauryl sulfate and / or sodium acetate.

[0023] Preferably, the mass ratio of the polyphenylene sulfide to the detergent aid in step (2) is 1:0.001 to 1:0.1, more preferably 1:0.01 to 1:0.05, and more preferably 1:0.02 to 1:0.03.

[0024] Preferably, in the above steps, the washing temperature in step (3) is 100-200°C.

[0025] Preferably, in the above steps, the washing with deionized water in step (3) is performed twice.

[0026] Preferably, in the above steps, the low boiling point alcohol solvent in step (4) is selected from methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, etc.

[0027] Preferably, in the above steps, the mass ratio of polyphenylene sulfide to the low-boiling point alcohol solvent in step (4) is 1:(1-10), and more preferably 1:(2-5).

[0028] Preferably, in the above steps, the drying temperature in step (4) is 110° C. and the drying time is 3-5 h.

[0029] Beneficial Effects

[0030] By adopting the high-temperature purification washing method of the present invention, the molecular chain segments are above the glass transition temperature during the washing process, which can significantly reduce the salt content in the polyphenylene sulfide resin; the use of surfactants can effectively reduce the content of inorganic salts in the product, and low-boiling point alcohols as washing liquids can significantly reduce the moisture and volatile matter in the product in subsequent treatment, reduce the product drying temperature, and avoid thermal oxygen cross-linking of the product during the drying process; adding surfactants can improve the compatibility of detergents and residual organic matter, enhance the purification effect, and reduce the volatile matter content; the technical solution is reasonably designed and simple to operate, which is conducive to industrialization. DETAILED DESCRIPTION

[0031] Hereinafter, the present invention will be described in detail. Before describing, it should be understood that the terms used in this specification and the appended claims should not be interpreted as being limited to the general meaning and dictionary meaning, but should be interpreted according to the meaning and concept corresponding to the technical aspects of the present invention on the basis of the principle that the inventor is allowed to appropriately define the terms for the best interpretation. Therefore, the descriptions presented here are only preferred examples for illustrative purposes and are not intended to limit the scope of the present invention, so that it should be understood that other equivalents or improvements can be obtained therefrom without departing from the spirit and scope of the present invention.

[0032] In this document, the terms "include", "including", "have", "contain" or any other similar terms are open conjunctions, which are intended to cover non-exclusive inclusions. For example, a composition or product containing multiple elements is not limited to the elements listed herein, but may also include other elements that are not explicitly listed but are generally inherent to the composition or product. In addition, unless otherwise explicitly stated, the term "or" refers to an inclusive "or" rather than an exclusive "or". For example, any of the following situations satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and A and B are both true (or exist). In addition, in this document, the interpretation of the terms "include", "including", "have", and "contain" should be considered to have been specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as "consisting of" and "consisting essentially of".

[0033] In this article, all features or conditions defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be deemed to have covered and specifically disclosed all possible secondary ranges and individual values ​​within the range, especially integer values. For example, the range description of "1 to 8" should be deemed to have specifically disclosed all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., especially secondary ranges defined by all integer values, and should be deemed to have specifically disclosed individual values ​​such as 1, 2, 3, 4, 5, 6, 7, 8, etc. within the range. Unless otherwise specified, the above interpretation method applies to all contents of the entire present invention, regardless of whether the range is broad or not.

[0034] If the quantity or other numerical value or parameter is expressed as a range, a preferred range or a series of upper and lower limits, it should be understood that all ranges consisting of any upper limit or preferred value of the range and the lower limit or preferred value of the range have been specifically disclosed herein, regardless of whether these ranges are disclosed separately. In addition, if a numerical range is mentioned herein, unless otherwise specified, the range should include its endpoints and all integers and fractions within the range.

[0035] In this document, under the premise of achieving the purpose of the invention, numerical values ​​should be understood to have the accuracy of the number of significant digits of the numerical value. For example, the number 40.0 should be understood to cover the range from 39.50 to 40.49.

[0036] In the purification method according to the present invention, the mass ratio of the polyphenylene sulfide to the detergent aid in step (2) is preferably 1:0.001 to 1:0.1, more preferably 1:0.01 to 1:0.05, and more preferably 1:0.02 to 1:0.03. If the amount of the detergent aid is less than 1:0.01, the inorganic salt cannot be fully removed; if the amount of the detergent aid is greater than 1:0.05, although the inorganic salt can be effectively removed from the final product, new residues of the washing solvent may be caused.

[0037] The following examples are only listed as examples of embodiments of the present invention and do not constitute any limitation to the present invention. It can be understood by those skilled in the art that modifications within the scope of the essence and concept of the present invention fall within the scope of protection of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are commercially available products.

[0038] The crude polyphenylene sulfide resin used in the following examples was produced by Binhua Group Co., Ltd., and had a heating loss of 0.3% at 150° C., a moisture content of about 0.4%, and a sodium content of about 2000 ppm.

[0039] Example 1

[0040] Add 4kg of N-methylpyrrolidone to a 10L reactor, then add 2kg of crude polyphenylene sulfide resin, heat to 180°C, stir for 4h, release the slurry, and filter. Take the filter cake and add it to a 15L reactor, add 10kg of deionized water, add 0.04kg of sodium acetate, heat to 150°C, stir for 3h, release the slurry and filter. Take the filter cake and add it to a 15L reactor, add 10kg of deionized water, heat to 150°C, stir for 3h, discharge, filter, and repeat the above washing process 2 times. Release the slurry, filter, take the filter cake and add it to a 10L reactor, add 4kg of ethanol, stir for 2h at room temperature, release the slurry, filter, add the filter cake to an oven, treat at 110°C for 5h, and obtain purified polyphenylene sulfide resin.

[0041] Example 2

[0042] Add 4kg N-methylpyrrolidone to a 10L reactor, then add 2kg of crude polyphenylene sulfide resin, heat to 120°C, stir for 3h, release the slurry, and filter. Take the filter cake and add it to a 15L reactor, add 10kg deionized water, add 0.04kg sodium dodecyl sulfate, heat to 180°C, stir for 3h, release the slurry and filter. Take the filter cake and add it to a 15L reactor, add 10kg deionized water, heat to 180°C, stir for 3h, discharge, filter, and repeat the above washing process 2 times. Release the slurry, filter, take the filter cake and add it to a 10L reactor, add 5kg methanol, stir for 3h at room temperature, release the slurry, filter, add the filter cake to an oven, treat at 110°C for 5h, and obtain purified polyphenylene sulfide resin.

[0043] Example 3

[0044] Add 4kg N-methylpyrrolidone to a 10L reactor, then add 2kg of crude polyphenylene sulfide resin, heat to 150°C, stir for 3h, release the slurry, and filter. Take the filter cake and add it to a 15L reactor, add 10kg deionized water, add 0.04kg of sodium dodecyl sulfate and sodium acetate, heat to 100°C, stir for 3h, release the slurry and filter. Take the filter cake and add it to a 15L reactor, add 10kg deionized water, heat to 100°C, stir for 5h, discharge, filter, and repeat the above washing process twice. Release the slurry, filter, take the filter cake and add it to a 10L reactor, add 5kg ethanol, stir for 3h at room temperature, release the slurry, filter, add the filter cake to an oven, treat at 110°C for 5h, and obtain purified polyphenylene sulfide resin.

[0045] Comparative Example 1

[0046] Add 4kg N-methylpyrrolidone to a 10L reactor, then add 2kg of crude polyphenylene sulfide resin, heat to 180°C, stir for 4h, release the slurry, and filter. Take the filter cake and add it to a 15L reactor, add 10kg deionized water, add 0.04kg dodecyl dimethyl benzyl ammonium chloride, heat to 150°C, stir for 3h, release the slurry and filter. Take the filter cake and add it to a 15L reactor, add 10kg deionized water, heat to 150°C, stir for 3h, discharge, filter, and repeat the above washing process twice. Release the slurry, filter, take the filter cake and add it to a 10L reactor, add 4kg ethanol, stir for 2h at room temperature, release the slurry, filter, add the filter cake to an oven, treat at 110°C for 5h to obtain purified polyphenylene sulfide resin.

[0047] Comparative Example 2

[0048] Add 4kg of N-methylpyrrolidone to a 10L reactor, then add 2kg of crude polyphenylene sulfide resin, heat to 180°C, stir for 4h, release the slurry, and filter. Take the filter cake and add it to a 15L reactor, add 10kg of deionized water, add 0.01kg of sodium acetate, heat to 150°C, stir for 3h, release the slurry and filter. Take the filter cake and add it to a 15L reactor, add 10kg of deionized water, heat to 150°C, stir for 3h, discharge, filter, and repeat the above washing process twice. Release the slurry, filter, take the filter cake and add it to a 10L reactor, add 4kg of ethanol, stir for 2h at room temperature, release the slurry, filter, add the filter cake to an oven, treat at 110°C for 5h, and obtain purified polyphenylene sulfide resin.

[0049] Comparative Example 3

[0050] Add 4kg of N-methylpyrrolidone to a 10L reactor, then add 2kg of crude polyphenylene sulfide resin, heat to 180°C, stir for 4h, release the slurry, and filter. Take the filter cake and add it to a 15L reactor, add 10kg of deionized water, add 0.16kg of sodium acetate, heat to 150°C, stir for 3h, release the slurry and filter. Take the filter cake and add it to a 15L reactor, add 10kg of deionized water, heat to 150°C, stir for 3h, discharge, filter, and repeat the above washing process twice. Release the slurry, filter, take the filter cake and add it to a 10L reactor, add 4kg of ethanol, stir for 2h at room temperature, release the slurry, filter, add the filter cake to an oven, treat at 110°C for 5h, and obtain purified polyphenylene sulfide resin.

[0051] Test Example 1

[0052] The present invention conducts performance tests on the purified polyphenylene sulfide resins prepared in the above Examples 1-3 and Comparative Examples 1-3, and the test methods are as follows:

[0053] 1. Determination of moisture content

[0054] The sample was placed in a sample pan and the moisture content of the resin was directly measured at 105°C using a halogen lamp direct moisture meter (Mettler HX204).

[0055] 2. Test of sodium ion content

[0056] The sample was placed in a crucible and heated in a muffle furnace at 710° C. for 4 h. The residue was dissolved with concentrated nitric acid and then fixed to volume with nitric acid. The obtained solution was tested for sodium ion content using ICP (Agilent 7500).

[0057] 3. Heating reduction test

[0058] Place the sample in a sample pan and weigh it. Heat the sample in an oven at 105°C for 1 hour, cool it in a desiccator to room temperature, and weigh it. Heat the sample in an oven at 150°C for 1 hour, cool it in a desiccator to room temperature, and calculate the weight loss.

[0059] The performance test results of the purified polyphenylene sulfide resin prepared in the above Examples 1-3 of the present invention are shown in Table 1.

[0060] project Before treatment Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Heating loss (%) 0.3 0.07 0.09 0.11 0.12 0.08 0.08 Moisture content (%) 0.4 0.21 0.10 0.19 0.15 0.23 0.16 Sodium ion content (ppm) 2000 11 13 22 1437 894 9*

[0061] *: Although the sodium ion content in Comparative Example 3 is low, unwashed surfactant is detected in the final product.

[0062] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for purifying polyphenylene sulfide resin, which can effectively remove the salt content and moisture in the polyphenylene sulfide resin, comprises the following steps: (1) adding a crude polyphenylene sulfide resin into an organic solvent, heating and stirring at a certain temperature, filtering, and collecting the filtrate; (2) adding deionized water and a detergent aid to the filtrate obtained in step (1), heating and stirring at a certain temperature, filtering, and collecting the filtrate; (3) adding deionized water to the filtrate obtained in step (2), heating and stirring at a certain temperature, filtering, and collecting the filtrate; (4) adding a low-boiling point alcohol solvent to the filtrate obtained in step (3), stirring and washing at room temperature, filtering, and drying to obtain a final polyphenylene sulfide product.

2. The purification method according to claim 1, characterized in that Preferably, in step (1), the mass ratio of the polyphenylene sulfide resin to the organic solvent is 1:(1-5), more preferably 1:(2-3); Preferably, the organic solvent in step (1) includes, but is not limited to, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, hexamethylphosphoramide, 1,3-dimethylimidazolidinone, nitrogen-containing organic compounds, sulfoxide-sulfone solvents, ether solvents, halogen-based solvents, and phenolic solvents; Further preferably, the nitrogen-containing organic compound is selected from 2-piperazinone; the sulfoxide-sulfone solvent is selected from dimethyl sulfone, dimethyl sulfoxide, etc.; the ketone solvent is selected from acetone, methyl ethyl ketone, acetophenone, etc.; the ether solvent is selected from dimethyl ether, dioxane, tetrahydrofuran, etc.; the halogen-based solvent is selected from chloroform, dichloromethane, trichloroethylene, dichloroethane, perchloroethylene, monochloroethane, dichloroethane, tetrachloroethane, perchloroethane, chlorobenzene, etc.; the phenolic solvent is selected from phenol and cresol; Preferably, the stirring time in step (1), step (2), step (3) and step (4) is 2-6 hours; Preferably, the stirring rate in step (1), step (2), step (3) and step (4) is 200 rpm; Preferably, the washing temperature in step (1) is 100-210°C.

3. The purification method according to claim 1, characterized in that Preferably, the mass ratio of polyphenylene sulfide to water in step (2) is 1:(3-10), more preferably 1:(5-8); Preferably, the washing temperature in step (2) is 100-200°C; Preferably, the washing aid in step (2) is a surfactant; Further preferably, the surfactant can be selected from one or more combinations of sodium lauryl ether sulfate, sodium lauryl sulfate, sodium stearate, sodium acetate, etc., more preferably sodium lauryl sulfate and / or sodium acetate; Preferably, the mass ratio of the polyphenylene sulfide to the detergent aid in step (2) is 1:0.001 to 1:0.1, more preferably 1:0.01 to 1:0.05, and more preferably 1:0.02 to 1:0.

03.

4. The purification method according to claim 1, characterized in that Preferably, in the above steps, the washing temperature in step (3) is 100-200°C; Preferably, in the above steps, the washing with deionized water in step (3) is performed twice.

5. The purification method according to claim 1, characterized in that Preferably, in the above steps, the low boiling point alcohol solvent in step (4) is selected from methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol; Preferably, in the above steps, the mass ratio of polyphenylene sulfide to the low-boiling point alcohol solvent in step (4) is 1:(1-10), more preferably 1:(2-5); Preferably, in the above steps, the drying temperature in step (4) is 110° C. and the drying time is 3-5 h.