阅读说明：本技术 注塑级聚苯硫醚工业产品的洗涤处理方法 (Washing treatment method of injection molding grade polyphenylene sulfide industrial product ) 是由 于国辉 李桂杰 张超 董新超 刘斌 于 2020-05-11 设计创作，主要内容包括：本发明公开了一种工业生产级别的注塑级聚苯硫醚产品的洗涤处理方法,该方法中,通过在特定条件下用压滤机,采用醋酸对聚苯硫醚树脂进行五次压滤,实现灰分降低,且可以有效提高聚苯硫醚在熔融态的结晶温度,有助于后续注塑成型的加工处理。根据本发明的洗涤处理方法工艺简单,洗涤效率高,处理设备为常规设备,安全,无危险药品,可以用于工业化生产。处理后的聚苯硫醚树脂,可以降低灰分降低且可以有效提高聚苯硫醚在熔融态的结晶温度,明显改善聚苯硫醚特性。每批次水洗水可以循环重复利用,有效减少了工艺中产生的废水,降低污水治理成本。(The invention discloses a washing treatment method of an injection molding grade polyphenylene sulfide product in an industrial production grade. The washing treatment method has the advantages of simple process, high washing efficiency, conventional treatment equipment, safety and no dangerous medicine, and can be used for industrial production. The treated polyphenylene sulfide resin can reduce ash content, effectively increase the crystallization temperature of polyphenylene sulfide in a molten state, and obviously improve the characteristics of polyphenylene sulfide. Each batch of washing water can be recycled, so that the waste water generated in the process is effectively reduced, and the sewage treatment cost is reduced.)

1. A washing treatment method of an industrial production grade injection molding grade polyphenylene sulfide product comprises the following steps:

1) conveying the injection molding grade polyphenylene sulfide crude product to a filter press, and adding water to carry out primary slurrying, wherein the weight ratio of the injection molding grade polyphenylene sulfide crude product to the filtrate is 1: 25-1: 5;

2) starting a stirring device of the filter press, stirring and mixing for 15min at 85-95 ℃, performing first filter pressing, and sending filtrate to a subsequent water treatment system;

3) after the filter pressing is finished, adding water into the filter press for secondary slurrying, wherein the weight ratio of the injection molding grade polyphenylene sulfide crude product to the filtrate is 1: 25-1: 5;

4) starting a stirring device of the filter press, stirring and mixing for 15min at 85-95 ℃, carrying out secondary filter pressing, and conveying filtrate to a washing water tank for temporary storage so as to facilitate washing and recycling of products of the next batch;

5) after filter pressing is finished, adding the filtrate obtained in the step 4) into a filter press for third slurrying, wherein the weight ratio of the injection molding grade polyphenylene sulfide crude product to the filtrate is 1: 25-1: 5;

6) repeating the step 4) for third filter pressing, and conveying the filtrate to a washing water tank for temporary storage so as to facilitate the washing recycling of the next batch of products;

7) after the filter pressing is finished, adding an acetic acid solution and the filtrate obtained in the step 6) into a filter press for carrying out fourth slurrying, and ensuring that the pH value of the mixed slurrying liquid is 4.5-5.0, so as to determine the dosage of the acetic acid solution, wherein the weight ratio of the injection molding grade polyphenylene sulfide crude product to the filtrate is 1: 25-1: 5;

8) starting a stirring device of the filter press, stirring and mixing for 15min at 85-95 ℃, performing fifth filter pressing, and sending filtrate to a subsequent water treatment system;

9) adding desalted water or distilled water into the filter press to carry out fifth slurrying;

10) and starting a stirring device of the filter press, stirring and mixing for 15min at 85-95 ℃, performing fifth filter pressing, conveying the injection-grade polyphenylene sulfide to a subsequent drying system from the filter press after the filter pressing is finished, and conveying filtrate to a washing water tank for temporary storage so as to facilitate next recycling, wherein the weight ratio of the injection-grade polyphenylene sulfide crude product to the desalted water or distilled water is 1: 25-1: 5.

2. The washing treatment method according to claim 1, characterized in that the weight ratio of injection-grade polyphenylene sulfide crude product to the filtrate in step 1) is 1: 10.

3. The washing treatment method according to claim 1, characterized in that the weight ratio of injection-grade polyphenylene sulfide crude product to the filtrate in step 3) is 1: 10.

4. The washing treatment method according to claim 1, characterized in that the weight ratio of injection-grade polyphenylene sulfide crude product to the filtrate in step 5) is 1: 10.

5. The washing treatment method as claimed in claim 1, wherein the weight ratio of the injection-grade polyphenylene sulfide crude product to the filtrate in step 7) is 1: 10.

6. The washing treatment method according to claim 1, characterized in that the weight ratio of the injection-grade polyphenylene sulfide crude product to the demineralized or distilled water in step 10) is 1: 10.

7. The washing treatment method according to claim 1, wherein the concentration of the acetic acid solution in step 7) is 5% to 30% by mass.

8. The washing treatment method according to claim 1, characterized in that the injection-grade polyphenylene sulfide raw product in step 1) is prepared as follows:

1) adding 20-30 parts by weight of acetic anhydride, 150 parts by weight of sodium hydroxide 140-;

2) and transferring the sodium hydrosulfide solution from the dehydration reaction kettle to a subsequent polymerization reaction kettle, adding 190-280 parts by weight of p-dichlorobenzene, heating the polymerization reaction kettle to 265-280 ℃, keeping the stirring condition for 0.5h for polymerization reaction, then cooling to below 100 ℃ under the condition of keeping the pressure in the reactor unchanged, and finishing the reaction to obtain the injection molding grade polyphenylene sulfide crude product.

9. The washing treatment method as claimed in claim 1, wherein the injection-grade polyphenylene sulfide crude product comprises the following components in percentage by weight: according to the mass percentage, 5 percent of NMP, 39 percent of sodium chloride, 12 percent of sodium acetate, 2 percent of water and the balance of 42 percent of PPS.

Technical Field

The invention belongs to the field of purification and washing treatment of industrial products, and particularly relates to a washing treatment method of an injection molding grade polyphenylene sulfide product in an industrial production grade.

Background

Polyphenylene Sulfide (PPS) is a semi-crystalline thermoplastic polymer with a crystallinity of about 29% to about 36%, a glass transition temperature of between 80 ℃ and 90 ℃, and a melting point of about 285 ℃. PPS is one of the most potential engineering plastics due to its excellent chemical resistance, low coefficient of friction, dimensional stability, high temperature resistance, and high flame retardancy.

In the process of industrially producing the polyphenylene sulfide resin, along with the generation of sodium chloride, an inorganic salt auxiliary agent is added, so that the environment for producing the polyphenylene sulfide has the existence of the inorganic salt, and the finally obtained polyphenylene sulfide resin is wrapped by a large amount of the inorganic salt and has residual solvent. The presence of these impurities reduces the mechanical properties, thermal stability, electrical insulation, etc. of polyphenylene sulfide resins, and also corrodes electronic components during use. Therefore, special washing treatment process is needed to reduce the content of inorganic salt and other impurities in the polyphenylene sulfide resin, so that the performance of the polyphenylene sulfide resin is better exerted, and the polyphenylene sulfide resin can be applied to various fields. In addition, the melt crystallization temperature is a key index for subsequent injection molding processing, the polyphenylene sulfide for injection molding requires a high melt crystallization temperature so as to be rapidly molded, and a proper washing treatment method is usually selected according to different purposes of the product.

According to the research, the invention discovers that the ash content of the specifically prepared crude polyphenylene sulfide product for injection molding can be reduced, the crystallization temperature of the polyphenylene sulfide in a molten state can be effectively increased, and the processing treatment of subsequent injection molding is facilitated by using acetic acid to treat the crude polyphenylene sulfide product for injection molding under specific conditions.

Disclosure of Invention

In view of the problems of the prior art, according to one aspect of the present invention, it is an object of the present invention to provide a method for washing and treating an injection-grade polyphenylene sulfide product of industrial production grade, wherein the injection-grade polyphenylene sulfide resin is treated with acetic acid under specific conditions, so that ash content is reduced, the crystallization temperature of the injection-grade polyphenylene sulfide in a molten state is effectively increased, and the subsequent processing of injection molding is facilitated.

The washing treatment method comprises the following steps:

1) conveying the injection molding grade polyphenylene sulfide crude product to a filter press, and adding water to carry out primary slurrying, wherein the weight ratio of the injection molding grade polyphenylene sulfide crude product to the filtrate is 1: 25-1: 5, and more preferably 1: 10;

2) starting a stirring device of the filter press, stirring and mixing for 15min at 85-95 ℃, performing first filter pressing, and sending filtrate to a subsequent water treatment system;

3) after the filter pressing is finished, adding water into the filter press for secondary slurrying, wherein the weight ratio of the injection molding grade polyphenylene sulfide crude product to the filtrate is 1: 25-1: 5, and more preferably 1: 10;

4) starting a stirring device of the filter press, stirring and mixing for 15min at 85-95 ℃, carrying out secondary filter pressing, and conveying filtrate to a washing water tank for temporary storage so as to facilitate washing and recycling of products of the next batch;

5) after the filter pressing is finished, adding the filtrate obtained in the step 4) into a filter press for third slurrying, wherein the weight ratio of the injection molding grade polyphenylene sulfide crude product to the filtrate is 1: 25-1: 5, and more preferably 1: 10;

6) repeating the step 4) for third filter pressing, and conveying the filtrate to a washing water tank for temporary storage so as to facilitate the washing recycling of the next batch of products;

7) after the filter pressing is finished, adding an acetic acid solution and the filtrate obtained in the step 6) into a filter press for carrying out fourth slurrying, and ensuring that the pH value of the mixed slurrying solution is 4.5-5.0, thereby determining the dosage of the acetic acid solution, wherein the weight ratio of the injection molding grade polyphenylene sulfide crude product to the filtrate is 1: 25-1: 5, and more preferably 1: 10;

8) starting a stirring device of the filter press, stirring and mixing for 15min at 85-95 ℃, performing fifth filter pressing, and sending filtrate to a subsequent water treatment system;

9) adding desalted water or distilled water into the filter press to carry out fifth slurrying;

10) and starting a stirring device of the filter press, stirring and mixing for 15min at 85-95 ℃, performing fifth filter pressing, sending the injection-grade polyphenylene sulfide to a subsequent drying system from the filter press after the filter pressing is finished, sending filtrate to a washing water tank for temporary storage so as to facilitate next recycling, wherein the weight ratio of the injection-grade polyphenylene sulfide crude product to the desalted water or distilled water is 1: 25-1: 5, and more preferably 1: 10.

Preferably, the concentration of the acetic acid solution in the step 7) is 5 to 30 percent by mass.

Preferably, the injection molding grade polyphenylene sulfide crude product in the step 1) is prepared as follows:

1) adding 20-30 parts by weight of acetic anhydride, 150 parts by weight of sodium hydroxide 140-;

2) and transferring the sodium hydrosulfide solution from the dehydration reaction kettle to a subsequent polymerization reaction kettle, adding 190-weight portions of dihalobenzene, heating the polymerization reaction kettle to 265-weight portions of 280 ℃, keeping the stirring condition for 0.5h for polymerization reaction, then cooling to below 100 ℃ under the condition of keeping the pressure in the reactor unchanged, and finishing the reaction to obtain the injection molding grade polyphenylene sulfide crude product.

The injection molding grade polyphenylene sulfide crude product comprises the following components in percentage by weight: according to the mass percentage, 5 percent of NMP, 39 percent of sodium chloride, 12 percent of sodium acetate, 2 percent of water and the balance of 42 percent of PPS.

The injection molding grade polyphenylene sulfide crude product is a polyphenylene sulfide product for injection molding, and is particularly suitable for being processed into a workpiece or a mold.

Advantageous effects

1. The method has the advantages of simple process, high washing efficiency, conventional treatment equipment, safety and no dangerous medicine, and can be used for industrial production.

2. The treated polyphenylene sulfide resin can reduce ash content, effectively increase the crystallization temperature of polyphenylene sulfide in a molten state, and obviously improve the characteristics of polyphenylene sulfide.

3. Each batch of washing water can be recycled, so that the waste water generated in the process is effectively reduced, and the sewage treatment cost is reduced.

4. The treated polyphenylene sulfide resin has improved application performance, can be better processed into a workpiece or a die, and is applied to high-end fields.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a DSC analysis chart of a product before washing treatment in example 1;

FIG. 2 is a DSC analysis chart of the product after the washing treatment of example 1.

Detailed Description

Hereinafter, the present invention will be described in detail. Before the description is made, it should be understood that the terms used in the present specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present invention on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. Accordingly, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the invention, so it should be understood that other equivalents and modifications could be made thereto without departing from the spirit and scope of the invention.

The washing treatment method needs to be carried out at a specific temperature, namely 85-95 ℃, and the residual solvent NMP in the injection molding grade polyphenylene sulfide product can be better washed within the temperature range, so that the NMP residue is reduced as much as possible. When the content is outside the above range, the effect of removing NMP as a solvent is not satisfactory.

The amount of water added per time in the washing treatment method according to the present invention is not particularly limited, but in view of efficiency and economy, the weight ratio of injection-grade polyphenylene sulfide crude product to the added water or filtrate is 1:25 to 1:5, more preferably 1: 10. If the ratio is more than 1:25, the added water or filtrate is too much, so that the impurity removal rate can be improved each time, but more waste water is generated, and the method is not economical and environment-friendly; if the ratio is less than 1:5, namely the added water or the filtrate is insufficient, the impurity removal rate per time is reduced, and the washing and pressure filtration times are increased to improve the total impurity removal rate, which is not economical.

According to the washing treatment method, the acetic acid solution is used as the washing additive for the injection molding grade crude polyphenylene sulfide product with specific components, impurities and contents, so that the content of the impurities in the injection molding grade crude polyphenylene sulfide product is greatly reduced. The acetic acid solution is added in the fourth pulping in the washing treatment method of the invention, and the pH value of the mixed pulping liquid is ensured to be 4.5-5.0, so that the dosage of the acetic acid solution is determined. If the pH value of the mixed slurry liquid in the fourth slurry process is lower than 4.5, the filtrate is too strong in acidity, and the burden of a subsequent water treatment system is caused; if the pH value is higher than 5.0, the optimum effect on the product is not significant, and it is further preferable that the pH value of the mixed slurry is 4.8.

The following examples are given by way of illustration of embodiments of the invention and are not to be construed as limiting the invention, and it will be understood by those skilled in the art that modifications may be made without departing from the spirit and scope of the invention. Unless otherwise specified, reagents and equipment used in the following examples are commercially available products.

And (3) performance testing:

1. the melt index change of polyphenylene sulfide before and after the washing treatment (temperature: 316 ℃ C., load: 5kg) was measured by a melt index meter.

2. The changes in the melting crystallization points before and after the washing treatment of the polyphenylene sulfide resin were measured by Differential Scanning Calorimetry (DSC).

3. The ash change of the polyphenylene sulfide resin before and after washing treatment can be tested by adopting a muffle furnace combustion method.