Preparation method and application of polyolefin solution metal deashing agent

Abstract

The invention discloses a preparation method and application of a polyolefin solution metal deashing agent. The preparation method comprises the following steps: 1) adding graphene oxide into water to obtain a graphene oxide dispersion; 2) adding a condensation activator into the graphene oxide dispersion, stirring and reacting at 20-120°C for 10-120min; 3) respectively adding triazine amidine and a condensation agent, stirring and reacting at 20-120°C for 10-120min; and 4) filtering, washing and drying to obtain the deashing agent.

Description

Technical Field

[0001] The invention relates to a metal deashing agent, in particular to a preparation method and application of a polyolefin solution metal deashing agent. Background Art

[0002] Polyolefin products are high-performance thermoplastic engineering plastics. Due to their excellent mechanical properties, thermal properties, dielectric properties, anti-aging properties, etc., they are widely used in aerospace, automotive parts, electronics, pipes and pipelines, communication equipment, medical equipment, optical lenses and other fields. At present, polyolefins have become a hot topic in the field of polymer material research, and their applications will be more extensive in the future.

[0003] Common polyolefin products are mostly produced by solution polymerization, and metal catalysts are required in the production process. The metal component residues contained in the catalysts will accelerate the degradation of polyolefins during use, making the thermal stability of polyolefins worse. At the same time, the presence of metal component residues will also have an adverse effect on the appearance, optical properties, and dielectric properties of the polymer. Therefore, reducing metal residues in polyolefin products has become an important link in improving the quality of polyolefin products.

[0004] In the production process of polyolefin products, the chelation adsorption method is mainly used to purify the residual metal components, that is, metal deashing. However, most of the organic small molecule chelating agents currently used in industrialization are difficult to deash and need to be carried out under high temperature and high pressure conditions (for example, 300°C, 5-10MPa pressure), and the metal deashing effect is limited. Therefore, it is still of great significance to develop polyolefin solution metal deashing agents with mild use conditions and high metal removal efficiency. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a preparation method and application of a polyolefin solution metal deashing agent. The metal deashing agent prepared by the method of the present invention has the advantages of large specific surface area, fast deashing rate, high metal removal rate, large adsorption capacity, low temperature applicability, etc., and can be widely used in the field of polyolefin deashing, and has versatility and high efficiency.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a polyolefin solution metal deashing agent comprises the following steps:

[0008] 1) adding graphene oxide to water to obtain a graphene oxide dispersion;

[0009] 2) adding a condensation activator to the graphene oxide dispersion, stirring and reacting at 20-120° C. for 10-120 min;

[0010] 3) adding triazine and condensing agent respectively, and stirring the reaction at 20-120° C. for 10-120 min;

[0011] 4) filtering, washing and drying to obtain the deliming agent.

[0012] Graphene oxide has the advantage of a large specific surface area and contains abundant polar functional groups such as carboxyl and hydroxyl groups, which can react with the amino groups in triazoline to form a structure containing an amide bond. The present invention has found through continuous research that the product prepared by the above process can be used as a metal deashing agent for polyolefin solutions, and has a high metal deashing efficiency, and can remove the metal content to less than 10ppm.

[0013] As a preferred embodiment, in step 1), the mass concentration of the graphene oxide dispersion is 0.5-200 mg / ml, preferably 20-80 mg / ml.

[0014] As a preferred embodiment, in step 2), the condensation activator is one or more of 4-N,N-dimethylaminopyridine (DMAP), 1-hydroxybenzotriazole (HOBt) and 4-pyrrolidinylpyridine (4-PPY);

[0015] Preferably, the added amount of the condensation activator is 0.001-0.2 times the mass of graphene oxide, preferably 0.001-0.1 times, and more preferably 0.001-0.01 times.

[0016] As a preferred embodiment, the reaction conditions in step 2) are stirring the reaction at 50-90° C. for 40-80 min.

[0017] As a preferred implementation, in step 3), the amount of triazoline added is 0.01-2 times, preferably 0.1-2 times, and more preferably 0.1-1 times the mass of graphene oxide.

[0018] As a preferred embodiment, in step 3), the condensing agent is one or more of N,N-dicyclohexylcarbodiimide (DCC), diisopropylcarbodiimide (DIC), 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDCI), 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU) and benzotriazole-1-yl-oxytripyrrolidinophosphine hexafluorophosphate (PyBOP);

[0019] Preferably, the amount of the condensing agent added is 0.001-0.2 times the mass of graphene oxide, preferably 0.001-0.1 times, and more preferably 0.001-0.01 times.

[0020] As a preferred embodiment, the reaction conditions in step 3) are stirring the reaction at 50-90° C. for 20-60 min.

[0021] The present invention also provides a use of the polyolefin solution metal deashing agent prepared according to the method described above in removing metal components in the polyolefin solution.

[0022] A method for metal deashing of polyolefin solution comprises: passing the polyolefin solution through an adsorption column filled with a polyolefin solution metal deashing agent prepared by the method described above, performing adsorption treatment, and obtaining a purified polyolefin solution.

[0023] As a preferred embodiment, the adsorption treatment conditions of the polyolefin solution are: temperature 30-300°C, preferably 50-150°C, pressure 0.1-10MPa, preferably 0.1-1Mpa;

[0024] Preferably, the flow rate of the polyolefin solution entering the adsorption column is 5-10 ml / min.

[0025] Preferably, the polyolefin solution is a cycloolefin copolymer (COC) solution, an ethylene-octene copolymer elastomer (POE) solution, a low-density polyethylene (LLDPE) solution, an ethylene-propylene-diene monomer rubber (EPDM) solution, a styrene-butadiene rubber (SBR) solution, etc.; the polyolefin solution may contain a metal content of 1000-50000 ppm, and the metal ions are preferably aluminum ions.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The deashing agent provided by the present invention can efficiently remove residual metals in polyolefin solutions, and has the advantages of simple preparation process, large specific surface area, fast deashing rate, high metal removal rate, and large adsorption capacity;

[0028] (2) Unlike the traditional chelating adsorption method which needs to be carried out under high temperature and high pressure conditions, the adsorbent provided by the present invention can unexpectedly achieve efficient removal of residual metals at a lower temperature;

[0029] (3) The deashing agent provided by the present invention is suitable for removing residual metals in a variety of polyolefin solutions and has versatility and high efficiency in different polyolefin solutions. DETAILED DESCRIPTION

[0030] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0031] Triazoline, 4-N,N-dimethylaminopyridine (DMAP), diisopropylcarbodiimide (DIC), 1-hydroxybenzotriazole (HOBt), 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDCI), 4-pyrrolidinylpyridine (4-PPY), 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU), benzotriazol-1-yl-oxytripyrrolidinophosphine hexafluorophosphate (PyBOP), n-hexane, methylcyclohexane, toluene, octene, and ethanol were purchased from AlfaAesar Chemicals;

[0032] Graphene oxide aqueous dispersion was purchased from Shanxi Coal Research Institute, Chinese Academy of Sciences;

[0033] rac-dimethylsilylbis(2-methylindenyl)zirconium dichloride was purchased from Beijing Inokai Technology Co., Ltd.;

[0034] Methylaluminoxane (MAO) was purchased from Chemtura Organometallics;

[0035] 2-Norbornene (NBE) was purchased from Tokyo Chemical Industry Co., Ltd. (TCI);

[0036] Ethylene was purchased from Air Liquide (Shanghai) Compressed Gas Co., Ltd.

[0037] The main testing methods involved in the present invention are as follows:

[0038] Adsorbent density: tested using Japan Shimadzu high-precision electronic density analysis balance AUY120.

[0039] Aluminum content in the sample: tested by Agilent inductively coupled plasma emission spectrometer (ICP), Agilent 8900, dual quadrupole detector, four-channel reaction cell for element qualitative and quantitative analysis.

[0040] Reactor: Cylindrical reactor, made of 316L stainless steel, reactor volume is 2L.

[0041] Adsorption column: Cylindrical reactor, made of 316L stainless steel, with dimensions of 40×400mm, and adsorption column volume of about 500mL.

[0042] The residence time of the polymer solution in the adsorption column is calculated as follows:

[0043] Residence time = (adsorption column volume - adsorbent effective filling volume) / polymer solution flow rate; wherein, adsorbent effective filling volume = adsorbent mass / adsorbent density.

[0044] Unless otherwise specified, pressure conditions in the present invention refer to gauge pressure.

[0045] The present invention relates to a method for preparing a reaction solution as follows:

[0046] Preparation of COC reaction solution: 500g of 2-norbornene and 2L of purified methylcyclohexane were added to a 5L reactor, the reactor was heated to 70°C, and then high-purity ethylene was introduced into the reactor to 0.5MPa. After the pressure was balanced, 0.74g of MAO and 4.5mg of rac-dimethylsilylbis(2-methylindenyl)zirconium dichloride were added to the reactor through the feeding bin to initiate polymerization. After 5 minutes of reaction, 1mL of ethanol was added to the reactor through the feeding bin and continued stirring for 5min to obtain COC reaction solution. Open the discharge valve at the bottom of the reactor, take 10mL of COC reaction solution, add 10mL of ethanol to precipitate COC solid, put it in a 70°C vacuum oven and dry it for 24h. ICP test showed that the aluminum content in the solid was 12466ppm.

[0047] Preparation of POE reaction solution: 300g of octene and 2L of purified toluene were added to a 5L reactor, the reactor was heated to 100°C, and then high-purity ethylene was introduced into the reactor to 3MPa. After the pressure was balanced, 0.74g of MAO and 4.5mg of rac-dimethylsilylbis(2-methylindenyl)zirconium dichloride were added to the reactor through the feeding bin to initiate polymerization. After 5 minutes of reaction, 1mL of ethanol was added to the reactor through the feeding bin and continued to stir for 5min to obtain POE reaction solution. Open the discharge valve at the bottom of the reactor, take 10mL of POE reaction solution, add 10mL of ethanol, precipitate POE solid, put it in a 70°C vacuum oven and dry it for 24h. ICP test showed that the aluminum content in the solid was 11698ppm.

[0048] Preparation of LLDPE reaction liquid: 50g of octene and 2L of refined n-hexane are added to a 5L reactor, the reactor is heated to 100°C, and then high-purity ethylene is introduced into the reactor to 3MPa. After the pressure is balanced, 0.74g of MAO and 4.5mg of rac-dimethylsilylbis(2-methylindenyl)zirconium dichloride are added to the reactor through the feeding bin to initiate polymerization. After 5 minutes of reaction, 1mL of ethanol is added to the reactor through the feeding bin and stirring is continued for 5min to obtain LLDPE reaction liquid. Open the discharge valve at the bottom of the reactor, take 10mL of LLDPE reaction liquid and add 10mL of ethanol to precipitate LLDPE solid, put it in a 70°C vacuum oven and dry it for 24h. ICP test shows that the aluminum content in the solid is 11762ppm.

[0049] [Example 1]

[0050] Preparation of deliming agent A:

[0051] 0.25g 4-N,N-dimethylaminopyridine (DMAP) was added to 10L of 20mg / ml graphene oxide aqueous dispersion for reaction at 50°C for 40min. 20g triazoline and 0.23g diisopropylcarbodiimide (DIC) were added to the above dispersion for further reaction at 50°C for 20min. The mixed solution was filtered, the precipitate was washed, and dried at 80°C for 4h to obtain 209.2g deashing agent A with a density of 1.019g / cm 3 .

[0052] [Example 2]

[0053] Preparation of deliming agent B:

[0054] 0.60g 1-hydroxybenzotriazole (HOBt) was added to 10L of 40mg / ml graphene oxide aqueous dispersion for reaction at 60°C for 50min. 120g triazoline and 0.78g 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDCI) were added to the above dispersion for further reaction at 60°C for 30min. The mixed solution was filtered, the precipitate was washed, and dried at 90°C for 4h to obtain 492.4g deashing agent B with a density of 1.078g / cm 3 .

[0055] [Example 3]

[0056] Preparation of deliming agent C:

[0057] 1.35g of 4-pyrrolidinylpyridine (4-PPY) was added to 10L of 60mg / ml graphene oxide aqueous dispersion for reaction at 80°C for 70min. 360g of triazoline and 3.80g of 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU) were added to the above dispersion for further reaction at 80°C for 50min. The mixed solution was filtered, the precipitate was washed, and dried at 110°C for 4h to obtain 895.8g of deashing agent C with a density of 1.138g / cm 3 .

[0058] [Example 4]

[0059] Preparation of deliming agent D:

[0060] 0.92g 4-N,N-dimethylaminopyridine (DMAP) and 1.01g 1-hydroxybenzotriazole (HOBt) were added to 10L of 80mg / ml graphene oxide aqueous dispersion for reaction at 90°C for 80min. 720g triazoline and 6.82g benzotriazole-1-yl-oxytripyrrolidinophosphine hexafluorophosphate (PyBOP) were added to the above dispersion for further reaction at 90°C for 60min. The mixed solution was filtered, the precipitate was washed, and dried at 120°C for 4h to obtain 1326.7g deashing agent D with a density of 1.183g / cm 3 .

[0061] [Comparative Example 1]

[0062] Preparation of deliming agent E:

[0063] 20 g of triazine was added to 10 L of 20 mg / ml graphene oxide aqueous dispersion and stirred at 50 °C for 20 min. The mixed solution was filtered, the precipitate was washed, and dried at 400 °C for 4 h to obtain 201.5 g of deashing agent E with a density of 1.011 g / cm 3 .

[0064] [Comparative Example 2]

[0065] Graphene oxide is directly used as deashing agent F.

[0066] The deashing agents prepared in each embodiment and comparative example were filled into the adsorption column, and the effective filling volume of the adsorption material was 450 mL. The adsorption column was heated, and different polyolefin reaction solutions were introduced under the conditions of 50°C, 100°C, 150°C, 200°C and 250°C, and the flow rate of each polymer solution was adjusted to 10 mL / min by a liquid flow meter. The same volume of ethanol was added to each polymer solution flowing out of the adsorption column, and the polymer was precipitated. After filtering, it was placed in a vacuum oven at 70°C and dried for 24 hours. The aluminum content was tested by ICP and recorded in Table 1.

[0067] Table 1. Deashing conditions and results of adsorption materials

[0068]

[0069]

[0070]

[0071] It can be seen from the above test results that the triazoline-graphene oxide deashing agent prepared by each embodiment of the present invention has a significant removal effect on the residual aluminum metal in the polymer solution, and can remove to less than 2ppm at the lowest. At the same time, unlike other chelating adsorbent materials, the deashing agent still has an excellent deashing effect at a relatively low temperature of 50-150°C. In Comparative Example 1, the scheme of using triazoline-loaded graphene oxide as an adsorbent material has a relatively limited removal effect on metallic aluminum, which is far from meeting the application requirements, and as the deashing temperature decreases, the metal removal effect significantly deteriorates. In Comparative Example 2, the scheme of using graphene oxide as an adsorbent material alone has a poor removal effect on metallic aluminum.

[0072] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a polyolefin solution metal deashing agent, characterized in that: The following steps are involved: 1) adding graphene oxide to water to obtain a graphene oxide dispersion; 2) adding a condensation activator to the graphene oxide dispersion, stirring and reacting at 20-120° C. for 10-120 min; 3) adding triazine and condensing agent respectively, and stirring the reaction at 20-120° C. for 10-120 min; 4) filtering, washing and drying to obtain the deliming agent; The condensation activator is one or more of 4-N,N-dimethylaminopyridine, 1-hydroxybenzotriazole and 4-pyrrolidinopyridine; The condensing agent is one or more of N,N-dicyclohexylcarbodiimide, diisopropylcarbodiimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate and benzotriazole-1-yl-oxytripyrrolidinophosphorus hexafluorophosphate.

2. The method for preparing a polyolefin solution metal deashing agent according to claim 1, characterized in that: In step 1), the mass concentration of the graphene oxide dispersion is 0.5-200 mg / ml.

3. The preparation method of the polyolefin solution metal deashing agent according to claim 2, characterized in that, In step 1), the mass concentration of the graphene oxide dispersion is 20-80 mg / ml.

4. The method for preparing a polyolefin solution metal deashing agent according to any one of claims 1 to 3, characterized in that: In step 2), the amount of the condensation activator added is 0.001-0.2 times the mass of graphene oxide.

5. The method for preparing a polyolefin solution metal deashing agent according to claim 4, characterized in that: In step 2), the amount of the condensation activator added is 0.001-0.1 times the mass of graphene oxide.

6. The method for preparing a polyolefin solution metal deashing agent according to claim 4, characterized in that: In step 2), the added amount of the condensation activator is 0.001-0.01 times the mass of graphene oxide.

7. The method for preparing a polyolefin solution metal deashing agent according to any one of claims 1 to 3, characterized in that: The reaction conditions in step 2) are: stirring the reaction at 50-90° C. for 40-80 min.

8. The method for preparing a polyolefin solution metal deashing agent according to any one of claims 1 to 3, characterized in that: In step 3), the amount of triazoline added is 0.01-2 times the mass of graphene oxide.

9. The method for preparing a polyolefin solution metal deashing agent according to claim 8, characterized in that: In step 3), the amount of triazoline added is 0.1-2 times the mass of graphene oxide.

10. The method for preparing a polyolefin solution metal deashing agent according to claim 8, characterized in that: In step 3), the amount of triazoline added is 0.1-1 times the mass of graphene oxide.

11. The method for preparing a polyolefin solution metal deashing agent according to any one of claims 1 to 3, characterized in that: In step 3), the amount of the condensing agent added is 0.001-0.2 times the mass of graphene oxide.

12. The method for preparing a polyolefin solution metal deashing agent according to claim 11, characterized in that: In step 3), the amount of the condensing agent added is 0.001-0.1 times the mass of graphene oxide.

13. The method for preparing a polyolefin solution metal deashing agent according to claim 11, characterized in that: In step 3), the amount of the condensing agent added is 0.001-0.01 times the mass of graphene oxide.

14. The method for preparing a polyolefin solution metal deashing agent according to claim 11, characterized in that: The reaction conditions in step 3) are stirring the reaction at 50-90°C for 20-60 minutes.

15. Use of the polyolefin solution metal deashing agent prepared according to the method according to any one of claims 1 to 14 in removing metal components from a polyolefin solution.

16. A method for metal deashing of polyolefin solution, characterized in that: include: The polyolefin solution is passed through an adsorption column filled with a polyolefin solution metal deashing agent prepared by the method according to any one of claims 1 to 14, and subjected to adsorption treatment to obtain a purified polyolefin solution.

17. The method for metal deashing of polyolefin solution according to claim 16, characterized in that: The adsorption treatment conditions of the polyolefin solution are: temperature 30-300° C., pressure 0.1-10 MPa.

18. The method for metal deashing of polyolefin solution according to claim 17, characterized in that: The adsorption treatment conditions of the polyolefin solution are: temperature 50-150° C., pressure 0.1-1 MPa.

19. The method for metal deashing of polyolefin solution according to claim 17, characterized in that: The flow rate of the polyolefin solution entering the adsorption column is 5-10 ml / min.

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