Process for inactivation and washing of olefin polymers

Abstract

The invention relates to an inactivation and washing process of an olefin polymer. The inactivation and washing process comprises the following steps: determining components of a hydroxyl medium serving as a polymerization reaction terminator based on polymerization reaction conditions; the prepared hydroxyl terminator is injected into a termination system through accurate metering, so that the hydroxyl terminator and a polymerization reaction material are fully mixed in the termination system; feeding the material after the reaction is terminated to an alkali washing system, and injecting alkali liquor into the alkali washing system at normal-pressure environment temperature for neutralization; feeding the alkali-washed material to a washing system, and injecting desalted water into the washing system at normal-pressure environment temperature to fully remove impurities in the polymer; and feeding the washed material into a separation system, and respectively feeding the separated olefin polymer and washing water to a downstream working section. According to the invention, efficient deactivation of the catalyst and deep removal of impurities are realized, so that the product quality is improved, and material consumption, energy consumption and wastewater discharge in the production process are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of polymer material synthesis, in particular to a deactivation and washing process of olefin polymers. Background Art

[0002] As an indispensable polymer material in modern industry and daily life, polyolefins occupy an important position in many fields due to their wide range of raw materials, low cost, good processing performance and excellent comprehensive performance. Among them, polyethylene, polypropylene, polyvinyl chloride and various copolymers such as ethylene-vinyl acetate copolymer, ethylene-acrylic acid or acrylate copolymer, etc., are widely used in the manufacture of films, pipes, plates, molded products and wires and cables, involving agriculture, packaging, electronics, electrical, automobiles, machinery, daily sundries and other industries.

[0003] In the polymerization reaction stage of polyolefin production, catalysts play a key role, but after the reaction is over, effectively terminating the polymerization and thoroughly removing the catalyst and other impurities become the key links to ensure product quality. Traditional processes have obvious shortcomings in this regard. For example, commonly used terminators may not be able to completely deactivate the catalyst, resulting in continued polymerization or side reactions, affecting the molecular weight distribution and performance stability of the product; in the washing process, a simple downstream washing method is often used, with a large amount of detergent and limited effect on impurity removal, which not only increases production costs, but also easily causes environmental pollution; at the same time, it is difficult for traditional processes to accurately control process parameters, resulting in large fluctuations in product quality, making it difficult to meet the strict requirements of the high-end market for polyolefin products.

[0004] Therefore, the development of a new olefin polymer deactivation and washing process technology has important practical significance and market demand. Summary of the invention

[0005] The purpose of the present invention is to provide a deactivation and washing process for olefin polymers. By introducing a specific hydroxyl medium as a polymerization terminator and combining it with a step countercurrent washing technology, efficient catalyst deactivation and deep removal of impurities are achieved, thereby improving product quality, reducing material consumption, energy consumption and wastewater discharge in the production process, and enhancing the competitiveness of polyolefin products in the market. At the same time, the process flow is simplified, production safety and stability are improved, and the operation cycle of the device is extended.

[0006] To achieve the above-mentioned object of the invention, the present invention provides a deactivation and washing process for olefin polymers, comprising the following steps:

[0007] determining the composition of the hydroxyl medium as a polymerization terminator based on the polymerization reaction conditions;

[0008] The prepared hydroxyl terminator is accurately metered and injected into the termination system, so that the hydroxyl terminator and the polymerization reaction material are fully mixed in the termination system;

[0009] The material after the termination of the reaction is sent to an alkali washing system, and alkali solution is injected into the alkali washing system at normal pressure and ambient temperature for neutralization;

[0010] The alkali-washed material is sent to a water washing system, and desalted water is injected into the water washing system at normal pressure and ambient temperature to fully remove impurities in the polymer;

[0011] The washed material enters the separation system, and the separated olefin polymer and washing water are sent to the downstream process section respectively.

[0012] According to a technical solution of the present invention, the hydroxyl medium includes an organic medium and an inorganic medium.

[0013] According to a technical solution of the present invention, the alkali washing system adopts countercurrent operation, and the operation time is 0.5-1h;

[0014] The water washing system adopts step-by-step countercurrent washing, and the operation time is 1-2 hours.

[0015] According to a technical solution of the present invention, the olefin polymer is ethylene-vinyl acetate copolymer, ethylene-acrylic acid or acrylic ester copolymer, polypropylene, propylene copolymer, poly-1-butene, poly-4-methyl-1-pentene, cycloolefin or polyisobutylene.

[0016] According to a technical solution of the present invention, the polymerization reaction conditions include one or more of polymerization temperature, pressure, catalyst type, monomer type and polymer composition.

[0017] According to a technical solution of the present invention, the type and concentration of the alkali solution are determined based on the properties of the polymerization reaction materials and the stoichiometric relationship of the neutralization reaction.

[0018] According to a technical solution of the present invention, the amount of alkali solution added is controlled between 7 and 8 according to the pH value of the material.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The deactivation and washing process of olefin polymers of the present invention improves the safety of polyolefin polymerization reaction, and the step-by-step washing technology can control the influence of key impurities and ash on product quality, making the polymerization system safer and easier to operate, and improving the competitiveness of polymer products. The present invention also has the characteristics of simple process, perfect safety control system, stable operation, low device investment, superb product quality, long operation cycle, etc.

[0021] The use of cascade countercurrent washing technology significantly reduces the consumption of detergents. Compared with the traditional downstream washing process, it can greatly save the amount of detergent used. At the same time, it reduces the material and energy consumption caused by multiple washings and large amounts of water, reduces production costs, and reduces the pollution of the production process to the environment. The recycling and resource reuse measures of washing water meet environmental protection requirements, realize green production, and have good social and environmental benefits.

[0022] In key links such as polymerization reaction termination, alkali washing and water washing, precise metering devices, online monitoring equipment and strict process parameter control are used to ensure that the operating conditions of each step are stable and reliable, thereby improving the safety of the production process and the stability of product quality, and effectively avoiding product performance differences caused by parameter fluctuations.

[0023] Specific hydroxyl terminators can effectively deactivate catalysts and reduce the impact of catalyst residues on product performance; the stepped countercurrent washing technology has a significant effect on the removal of impurities and ash, which can effectively control the impurity content in the product and improve the purity and performance indicators of polymer products, such as improving the mechanical strength, thermal stability and electrical insulation of the product, so that the product quality meets or exceeds industry standards and enhances the competitiveness of the product in the high-end market. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A flow chart schematically illustrates a deactivation and washing process of an olefin polymer according to one embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0027] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0028] like Figure 1 As shown, according to one embodiment of the present invention, a deactivation and washing process of an olefin polymer of the present invention mainly includes the processes of polymerization reaction termination, alkali washing and neutralization, water washing and impurity removal, separation and subsequent treatment. Among them, the termination system 1 is used to mix the hydroxyl terminator with the polymerization reaction material to achieve the termination of the polymerization reaction. The system is equipped with a precise metering device and an efficient stirring device to ensure that the hydroxyl terminator is evenly mixed with the material to quickly deactivate the catalyst; the alkali washing system 2 performs alkali washing and neutralization operation on the material after the termination reaction, and has a built-in online pH monitoring device and a countercurrent device to monitor and adjust the amount of alkali solution added in real time to ensure the neutralization effect; the water washing system 3 further removes impurities in the material after alkali washing, and adopts countercurrent operation and adjustable water flow and temperature control devices to improve the washing efficiency; the separation system 4 realizes the separation of the polymer and the washing water, and transports them to the downstream section respectively. The appropriate separation method can be selected according to the material characteristics, such as centrifugal separation or filtration separation.

[0029] Termination of polymerization reaction: A specific hydroxyl medium (including organic hydroxyl compounds and inorganic hydroxyl compounds) is selected as a polymerization terminator. In the termination system 1, the hydroxyl medium is first accurately formulated, and the best formula is determined by considering its compatibility with the polymerization reaction system and its targeted deactivation effect on the catalyst. Then, the prepared hydroxyl terminator is injected into the termination system 1 through a high-precision metering device to ensure that it is fully mixed with the polymerization reaction materials under suitable temperature, pressure and stirring conditions, so that the catalyst is quickly deactivated and the polymerization reaction is terminated.

[0030] Alkali washing and neutralization: The deactivated polymer material is transported to the alkali washing system 2. During the alkali washing process, according to the chemical properties and acid-base characteristics of the material, a suitable alkali solution (such as sodium hydroxide, potassium hydroxide or ammonia water, etc.) is selected for neutralization operation. Through the online pH monitoring equipment, the amount of alkali solution added is strictly controlled to stabilize the pH value of the material between 7-8 to ensure that the acidic impurities are completely neutralized. The alkali washing system 2 adopts a countercurrent operation mode at normal pressure ambient temperature, and uses the countercurrent principle to increase the contact time and contact area between the material and the alkali solution, thereby improving the neutralization reaction efficiency. The operation time is determined according to the nature of the material, the impurity content and the washing effect, and is generally about 0.5-1h. For example, for materials containing more acidic catalyst residues, the operation time can be appropriately extended or the alkali solution concentration can be adjusted to ensure the neutralization effect.

[0031] Water washing and impurity removal: The material after alkali washing enters the water washing system 3. In the water washing system 3, pre-treated desalted water is injected, and the purity of the desalted water must meet a certain standard to avoid the introduction of new impurities. Countercurrent operation is adopted to make the desalted water fully contact with the polymer material, and the residual alkali solution, catalyst residue, water-soluble impurities, etc. in the polymer are completely removed by utilizing the solubility and flushing effect of water. The operation time of the water washing system 3 is set to about 1-2h according to the complexity of the material and the washing requirements. At the same time, the washing effect can be optimized by adjusting the flow rate, temperature and number of washing times of the desalted water. For example, for some polyolefin products with extremely high requirements for impurity content, the number of water washings can be increased or a multi-stage water washing series method can be adopted to further reduce the impurity content.

[0032] Separation and subsequent treatment: The washed materials are sent to the separation system 4, which can use centrifugal separation, filtration separation or a combination of the two to ensure efficient separation of polymer and washing water. The separated polymer is subjected to subsequent treatment processes such as drying and granulation, and is sent to the downstream process for application after meeting the product standards; the washing water is treated to recover the useful components or meet the discharge standards, so as to achieve resource recycling and environmental protection.

[0033] The present invention is specifically described below with examples.

[0034] Example 1: Deactivation and washing process of polyethylene polymer

[0035] For the polyethylene polymerization reaction system, a specific organic hydroxyl compound (such as monohydroxy organic alcohol R-OH) is selected as a hydroxyl terminator. The optimal formula and preparation method of the terminator are determined based on the polymerization reaction characteristics of polyethylene and the type of catalyst. For example, if [triethylaluminum] is used, the termination effect is best when the molar ratio of [organic hydroxyl compound] to [catalyst] is [9]:[1] as determined by experiments. The prepared hydroxyl terminator is accurately metered and injected into the termination system. Under appropriate stirring speed and temperature conditions, it is fully mixed with the polyethylene polymerization reaction materials to quickly deactivate the catalyst and terminate the polymerization reaction.

[0036] After the reaction is terminated, the polyethylene material enters the alkali washing system. Sodium hydroxide solution is selected as the alkali solution for neutralization operation. The amount of alkali solution added is strictly controlled through the online pH monitoring equipment to stabilize the pH value of the material between 7 and 8. Under normal pressure and ambient temperature, the countercurrent operation mode is adopted, and the operation time is about 0.5h. According to the impurity content and washing effect of the material, the concentration and flow rate of the alkali solution can be appropriately adjusted to ensure that the neutralization reaction is fully carried out and the acidic impurities in the material are effectively removed.

[0037] The polyethylene material after alkali washing enters the water washing system. A sufficient amount of desalted water is injected, and the countercurrent operation principle is used to make the desalted water fully contact with the polyethylene material. The operation time is about 1 hour. During the water washing process, the temperature and flow rate of the desalted water can be adjusted as needed to improve the washing effect. For example, controlling the temperature of the desalted water at 40°C can enhance the solubility of certain impurities, more effectively remove impurities such as residual alkali solution and catalyst residues in polyethylene, and ensure the purity of the polyethylene product.

[0038] The washed polyethylene material is sent to the separation system, where centrifugal separation or filtration separation is used to effectively separate the polyethylene polymer and the washing water. The separated polyethylene undergoes subsequent treatment processes such as drying and granulation to meet the quality requirements of the downstream processing section, such as meeting the specified molecular weight distribution, particle shape and purity standards; the washing water is recycled or discharged in compliance with the standards after treatment, reducing water resource waste and environmental pollution.

[0039] Example 2: Deactivation and washing process of polypropylene polymer

[0040] For the polypropylene polymerization reaction, a specific organic hydroxyl compound (such as monohydroxyl organic alcohol R-OH) is selected as a hydroxyl terminator. The preparation scheme and injection amount of the terminator are determined according to the polymerization process of polypropylene and the characteristics of the catalyst. For example, for [triethylaluminum], the molar ratio of [organic hydroxyl compound] to [catalyst] is

[10] :[1] to achieve the best catalyst deactivation effect. The prepared hydroxyl terminator is accurately injected into the termination system, fully mixed with the polypropylene polymerization reaction materials, and the polymerization reaction is terminated.

[0041] The deactivated polypropylene material enters the alkali washing system and is injected with potassium hydroxide solution for neutralization. According to the real-time pH value of the material, the amount of alkali solution added is accurately controlled to maintain it within the range of 7-8. Under normal pressure and ambient temperature, countercurrent operation is adopted, and the operation time is about 0.8h. During the alkali washing process, pay close attention to the reaction of the material, and adjust the concentration of the alkali solution and the operation time in time according to the impurity content and washing effect to ensure the neutralization effect and remove acidic impurities.

[0042] After alkali washing, the material enters the water washing system and is injected with desalted water for countercurrent washing. The operation time is about 1.5 hours. By optimizing the washing parameters of desalted water, such as adjusting the flow rate, temperature and number of washings, the impurities in polypropylene can be fully removed. For example, increasing the flow rate and number of washings of desalted water can effectively remove the residual alkali solution, catalyst residues and other water-soluble impurities in polypropylene and improve product quality.

[0043] The washed materials are sent to the separation system to separate the polymer and the washing water. The separated polypropylene undergoes subsequent processing, such as adding stabilizers, antioxidants and other additives to meet the performance requirements of downstream products; the washing water is recycled or discharged in compliance with the standards after treatment, reducing production costs and environmental impact.

[0044] Example 3: Deactivation and washing process of polyisobutylene or polybutene-1 polymer

[0045] For the production of polyisobutylene or polybutene-1 polymers, a specific hydroxy organic medium (such as dihydroxy organic alcohol HO-R-OH) is selected as a terminator according to its chemical structure and polymerization characteristics, and is reasonably prepared. For example, under specific polymerization conditions, when the molar ratio of [hydroxy organic medium] to [catalyst] is [3]:[1], the polymerization reaction can be effectively terminated without producing adverse side reactions. The prepared hydroxy terminator is injected into the termination system and fully mixed with the polymerization reaction materials to terminate the polymerization reaction.

[0046] After the reaction is terminated, the material enters the alkali washing system. Due to the chemical characteristics of the copolymer, a suitable weak alkali solution (such as ammonia water) is selected for neutralization. According to the pH value of the material, the amount of alkali solution added is carefully controlled to keep the pH value between 7-8. Under normal pressure and ambient temperature, countercurrent operation is adopted, and the operation time is about 1h. During the alkali washing process, pay attention to controlling the reaction temperature and alkali concentration to avoid damage to the copolymer structure, while ensuring that the neutralization reaction is thorough and the acidic substances are effectively removed.

[0047] The material after alkali washing enters the water washing system and is injected with desalted water for countercurrent washing. The operation time is about 2 hours. By optimizing the water washing process parameters, such as increasing the purity of desalted water, adjusting the washing time and temperature, the impurities and residual alkali solution in the copolymer can be fully removed. For example, using high-purity desalted water and controlling the washing temperature at 35°C can effectively remove impurities in polyisobutylene or polybutene-1 polymers and improve the transparency, flexibility and weather resistance of the product.

[0048] The washed materials are sent to the separation system to separate the polymer and the washing water. The separated polyisobutylene or polybutene-1 polymer is sent to the downstream section for subsequent processing, such as making films, injection molding products, etc. The washing water is treated and discharged or recycled to meet the standards, reducing the impact on the environment and achieving green production.

[0049] The above contents are merely examples of specific solutions of the present invention. For devices and structures not described in detail therein, it should be understood that they can be implemented by adopting general devices and general methods available in the art.

[0050] The above is only one solution of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A deactivation and washing process for olefin polymers, characterized in that: The following steps are involved: determining the composition of the hydroxyl medium as a polymerization terminator based on the polymerization reaction conditions; The prepared hydroxyl terminator is accurately metered and injected into the termination system (1), so that the hydroxyl terminator and the polymerization reaction material are fully mixed in the termination system (1); The material after the reaction is terminated is sent to an alkali washing system (2), and an alkali solution is injected into the alkali washing system (2) at normal pressure and ambient temperature for neutralization; The alkali-washed material is sent to a water washing system (3), and desalted water is injected into the water washing system (3) at normal pressure and temperature to fully remove impurities in the polymer; The washed material enters the separation system (4), and the separated olefin polymer and washing water are respectively sent to the downstream process section.

2. The deactivation and washing process of olefin polymers according to claim 1, characterized in that: The hydroxyl medium includes an organic medium and an inorganic medium.

3. The deactivation and washing process of olefin polymers according to claim 1, characterized in that: The alkaline washing system (2) adopts countercurrent operation, and the operation time is 0.5-1h; The water washing system (3) adopts step-by-step countercurrent washing, and the operation time is 1-2 hours.

4. The deactivation and washing process of olefin polymers according to claim 1, characterized in that: The olefin polymer is ethylene-vinyl acetate copolymer, ethylene-acrylic acid or acrylic ester copolymer, polypropylene, propylene copolymer, poly-1-butene, poly-4-methyl-1-pentene, cycloolefin or polyisobutylene.

5. The deactivation and washing process of olefin polymers according to claim 1, characterized in that: The polymerization reaction conditions include one or more of polymerization temperature, pressure, catalyst type, monomer type and polymer composition.

6. The deactivation and washing process of olefin polymers according to claim 1, characterized in that: The type and concentration of the alkali solution are determined based on the properties of the polymerization materials and the stoichiometric relationship of the neutralization reaction.

7. The deactivation and washing process of olefin polymers according to claim 1, characterized in that: The amount of alkali solution added is controlled between 7-8 according to the pH value of the material.

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