A continuous decolorization method and system for a vinyl elastomer resin

Abstract

The application provides a continuous decolorization method and system of a vinyl elastomer resin, and the continuous decolorization method of the vinyl elastomer resin comprises the following steps: performing adsorption treatment on a vinyl elastomer resin solution containing an alpha-diimine type ligand; and the adsorbent used in the adsorption treatment comprises a first adsorbent and a second adsorbent, the first adsorbent comprises at least one of a metal oxide and a non-metal oxide, and the second adsorbent comprises cellulose acetate. The continuous decolorization method of the vinyl elastomer resin provided by the application adopts the first adsorbent such as a metal oxide and a non-metal oxide and the second adsorbent such as a cellulose derivative (for example, cellulose acetate) as the adsorbent, can remove the ppm-level catalyst ligand in the vinyl elastomer resin solution, ensures that the color of the resin after treatment is colorless and transparent, and ensures the aging resistance of the application end. The method is simple in process, green and environment-friendly, and easy to be industrialized.

Description

Technical Field

[0001] This application relates to the field of polyolefin production and purification technology, and in particular to a continuous decolorization method and system for vinyl elastomer resins. Background Technology

[0002] Vinyl polyolefin elastomer, or EPE for short, is a branched polyethylene produced through a "chain-walking" process using an α-diimide-type post-transition metal catalyst. It is a thermoplastic elastomer made solely from ethylene, eliminating the need for costly high-carbon α-olefins. It maintains the high elasticity of rubber at room temperature and is easily plasticized and molded at high temperatures, possessing the dual characteristics of both plastics and rubber. It exhibits high transparency, thermal stability, good aging resistance, excellent processability, and superior physical and mechanical properties, making it widely applicable in photovoltaic sealants, automotive parts, wire and cable insulation, hot melt adhesives, plastic modifiers, extruded hoses, and nonwoven fabrics.

[0003] Currently, the polyolefin elastomer market is monopolized by foreign giants such as Dow and Mitsui. Industries such as photovoltaics are highly dependent on imported raw materials. Due to the blockade of metallocene catalysts and α-olefin preparation technology, it is difficult to achieve domestic production of the entire process from catalysts to polymerization processes to post-processing processes, which further restricts the progress of domestic substitution of end products. α-olefin and catalyst technologies are only mastered by a few companies, with high technological barriers. They account for about 60% of the profit in the POE industry chain. Therefore, the EPE technology route has good potential for domestic substitution based on my country's national conditions and the current status of the polyolefin industry.

[0004] In this process for preparing EPE, after polymerization, metal or halide ions such as Ni, Br, Al, and Cl can be removed by washing with water. However, α-diimide ligands are insoluble in water and remain in the resin solution. Due to their high boiling point, they cannot be removed by flash evaporation, and because they are highly compatible with the resin solution, they cannot be removed by traditional washing methods. Therefore, they affect the color of the resin, resulting in a yellow appearance. If the residual catalyst ligands are not removed, they will have a negative impact on the aging performance of the final application. Therefore, it is necessary to design a continuous decolorization method to ensure that the resin color meets the requirements of similar foreign products.

[0005] Some related technologies disclose a deashing adsorption packing, its preparation method, and its application in polyolefin deashing, which can efficiently remove residual metals from polyolefin solutions and significantly reduce metal residues in polyolefin products. However, these technologies are mainly targeted at metallocene catalyst systems to remove metal ions from resin solutions.

[0006] Other related technologies disclose post-treatment methods for vinyl polymers, which remove metal ions such as Al and Ni from the polymerization solution using a single alumina column to solve the problem of ash removal from polyolefin resin solutions. However, these methods do not report on the removal effect of catalyst ligands, nor do they provide further explanation on the appearance color of the resin after post-treatment.

[0007] Other related technologies disclose methods for removing ash from polyolefin organic solutions. These methods involve contacting an ash-removing agent with the polyolefin organic solution, allowing the ash to be removed through adsorption and complexation by the ash-removing agent. The ash-removed polyolefin organic solution is then separated from the ash-removing agent to obtain a purified polyolefin organic solution. The ash-removing agent includes at least one of polyaluminum chloride and bentonite. However, these methods only report on the removal of metal ions from the catalyst and do not investigate the effectiveness of the catalyst removal ligand, or further characterize the appearance and aging properties of the resulting resin.

[0008] In summary, current technologies mainly focus on metal ion removal, but rarely mention methods for removing α-diimine-type post-transition catalyst ligands. Catalyst ligands are organic compounds with good compatibility with resins. Failure to remove them not only affects the resin's appearance, causing yellowing, but also negatively impacts its aging resistance. In the photovoltaic encapsulant industry, long-term exposure to outdoor environments can lead to yellowing and browning. This discoloration reduces the film's light transmittance, resulting in a decrease in the photocurrent of photovoltaic cells and ultimately power loss in photovoltaic modules. Therefore, the most critical step in the commercialization of the α-diimine-type post-transition catalyst process for preparing vinyl elastomers is the removal of catalyst ligands, especially a continuous removal process for tens of thousands of tons of products. This process represents a significant challenge and key factor in industrialization costs and efficiency. Summary of the Invention

[0009] To address the shortcomings of related technologies, one objective of this application is to provide a continuous decolorization method for vinyl elastomer resins. This method employs a first adsorbent such as a metal oxide / non-metal oxide and a second adsorbent such as a cellulose derivative (e.g., cellulose acetate) to remove catalyst ligands at the ppm level from the vinyl elastomer resin solution, ensuring the treated resin is colorless and transparent, thus guaranteeing its aging resistance in applications. This method is simple, environmentally friendly, and easily scaled up for industrial use.

[0010] Another object of this application is to provide a continuous decolorization system for vinyl elastomer resins.

[0011] Therefore, the first aspect of this application proposes a continuous decolorization method for vinyl elastomer resins, comprising:

[0012] The vinyl elastomer resin solution containing α-diimine ligands was subjected to adsorption treatment;

[0013] The adsorbent used in the adsorption treatment includes a first adsorbent and a second adsorbent. The first adsorbent includes at least one of metal oxides and non-metal oxides; the second adsorbent includes a cellulose derivative.

[0014] In some embodiments, the adsorption treatment includes:

[0015] A vinyl elastomer resin solution containing an α-diimine ligand is sequentially adsorbed by the first adsorbent and then by the second adsorbent.

[0016] In other embodiments, the adsorption treatment includes:

[0017] A vinyl elastomer resin solution containing an α-diimine ligand is sequentially adsorbed by the second adsorbent and then by the first adsorbent.

[0018] In some embodiments, the metal oxide includes at least one of aluminum oxide, calcium oxide, and magnesium oxide.

[0019] In some embodiments, the non-metallic oxide includes at least one of silicon dioxide and diatomaceous earth.

[0020] In some embodiments, the average particle size of the first adsorbent is 1-20 mm, optionally 1-10 mm, and further optionally 1-4 mm.

[0021] In some embodiments, the cellulose derivative is in powder form.

[0022] In some embodiments, the cellulose derivative includes at least one of cellulose acetate, cellulose ether, and cellulose ester, and may be cellulose acetate, more preferably cellulose acetate with an AC content of 53-56 mol%.

[0023] In some embodiments, the temperature of the adsorption treatment is 50-200°C, optionally 70-150°C.

[0024] In some embodiments, the pressure of the adsorption treatment is x MPa, the saturated vapor pressure of the solvent in the vinyl elastomer resin solution containing the α-diimine ligand at the adsorption treatment temperature is y MPa, and x and y satisfy: x > y.

[0025] In some embodiments, the pressure of the adsorption treatment is 0.1-0.5 MPa, optionally 0.2-0.4 MPa.

[0026] In some embodiments, the adsorption treatment time is 0.5-5 BV / h, optionally 0.5-3 BV / h.

[0027] In some embodiments, the mass ratio of the first adsorbent to the second adsorbent is (1-10):1, and may be (1-5):1.

[0028] In some embodiments, the solvent in the vinyl elastomer resin solution containing the α-diimine ligand includes alkane compounds.

[0029] In some embodiments, the continuous decolorization method for the vinyl elastomer resin further includes the step of heating the vinyl elastomer resin solution containing the α-diimine ligand prior to adsorption.

[0030] In some embodiments, the vinyl elastomer resin solution containing the α-diimine ligand is heated to a temperature of 50-200°C.

[0031] In some embodiments, the continuous decolorization method for the vinyl elastomer resin further includes the step of sequentially loading the first adsorbent and the second adsorbent into an adsorption packing column.

[0032] The second aspect of this application discloses a continuous decolorization system for vinyl elastomeric resins, applied to the continuous decolorization method for vinyl elastomeric resins described in this application, comprising:

[0033] An adsorption packed column, wherein the adsorption packed column is filled with the first adsorbent and the second adsorbent;

[0034] A delivery pump is connected to a container for storing the vinyl elastomer resin solution containing the α-diimine ligand and the adsorption packing column.

[0035] The continuous decolorization method for vinyl elastomer resins described in this application can bring at least the following beneficial effects:

[0036] 1. By using metal oxides / non-metal oxides as the primary adsorbent and cellulose derivatives (e.g., cellulose acetate) as the secondary adsorbent, ppm-level catalyst ligands in vinyl elastomer resin solutions can be removed, ensuring that the treated resin is colorless and transparent, and guaranteeing the aging resistance of the application.

[0037] 2. The process is simple, the raw materials are readily available, and the treatment effect is good. This method has high separation efficiency, high product purity, and all related adsorbents can be regenerated and reused. The whole process is green and environmentally friendly and easy to scale up industrially.

[0038] The continuous decolorization system for vinyl elastomer resins described in this application has at least the beneficial effects of the continuous decolorization method for vinyl elastomer resins described in this application.

[0039] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0040] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings.

[0041] in:

[0042] Figure 1 These are comparative photographs of the appearance of the dry resin in Examples 1-6 and Comparative Example 2. Detailed Implementation

[0043] The embodiments of this application are described in detail below. These embodiments are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0044] In this application, the disclosure of numerical ranges includes all values ​​throughout the range and the disclosure of further subdivisions of the range, including the endpoints and subranges given for these ranges.

[0045] Unless otherwise specified, all raw materials and equipment involved in this application are self-made through commercial means or known methods; and all methods involved are conventional methods unless otherwise specified.

[0046] When the term “and / or” is used in a list containing two or more items, it means that any of the listed items can be used alone or in combination with any one or more of the listed items. For example, the expression “A and / or B” is intended to mean A or B or A and B, that is, A only, B only, or a combination of A and B.

[0047] In this application, room temperature refers to 20-30℃.

[0048] <Continuous Decolorization Method for Vinyl Elastomer Resins>

[0049] The continuous decolorization method for vinyl elastomer resin according to embodiments of this application includes: adsorbing a vinyl elastomer resin solution containing an α-diimine ligand; the adsorbent used in the adsorption treatment includes a first adsorbent and a second adsorbent, wherein the first adsorbent includes at least one of a metal oxide and a non-metal oxide; and the second adsorbent includes a cellulose derivative.

[0050] It should be noted that the embodiments of this application do not limit the specific composition of the vinyl elastomer resin solution containing α-diimine ligands, and can be any vinyl elastomer resin solution containing α-diimine ligands known in the art.

[0051] For example, a vinyl elastomer resin solution containing an α-diimine ligand includes a solvent, a catalyst, and a vinyl elastomer. The catalyst includes an α-diimine catalyst; this application does not limit the specific structure of the α-diimine catalyst, and it can be any α-diimine catalyst well known in the art.

[0052] For example, the catalyst with the structural formula of Formula I involved in Chinese patent application CN119552177A:

[0053]

[0054] In Equation I, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 Each is independently selected from H, F, Cl, Br, I, NO2, trifluoromethyl, CN, benzyl, diphenylmethyl, C 1-6 Alkyl, C 1-6 The alkoxy groups, X1 and X2, are each independently selected from one of F, Cl, Br, and I.

[0055] For example, a catalyst with the structural formula of formula II:

[0056]

[0057] In Formula II, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 Each is independently selected from H, F, Cl, Br, I, NO2, trifluoromethyl, CN, benzyl, diphenylmethyl, C 1-6 Alkyl, C 1-6 The alkoxy groups, X1 and X2, are each independently selected from one of F, Cl, Br, and I.

[0058] An exemplary method for obtaining a vinyl elastomer resin solution containing an α-diimine ligand is as follows: using an α-diimine catalyst and sesquialuminum as a co-catalyst, and n-hexane as a polymerization solution (i.e., solvent), branched polyethylene is produced by solution polymerization. The continuous polymerization reaction is carried out at a pressure of 10 kg ethylene and a temperature of 70°C. A small amount of high-purity water is added to the polymerized resin solution to deactivate it and terminate the reaction.

[0059] It should be noted that the amounts of α-diimide catalyst, sesquialuminum, and n-hexane involved in the above polymerization reaction, as well as the polymerization reaction time, have no effect on the composition of the resin solution of the target dehydration product or the final decolorization effect.

[0060] It is understood that the adsorbent involved in the embodiments of this application may be packed into an adsorption packed column (or an adsorption packed tower (hereinafter referred to as an adsorption tower)) as needed, or it may simply be packed into another container (e.g., a reaction vessel, a storage tank, etc.) for static or dynamic adsorption. If necessary, a vinyl elastomer resin solution containing α-diimine ligands may be transported to the adsorption packed column or other container filled with the adsorbent by a transfer pump (e.g., a gear pump or a melt pump, etc.).

[0061] In the embodiments of this application, the adsorption treatment method is not limited, and can be at least one of the following three methods:

[0062] (1) A vinyl elastomer resin solution containing α-diimine ligands is sequentially adsorbed by the first adsorbent and then by the second adsorbent.

[0063] (2) The vinyl elastomer resin solution containing α-diimine ligand is sequentially adsorbed by the second adsorbent and then by the first adsorbent.

[0064] (3) The vinyl elastomer resin solution containing α-diimine ligands is adsorbed by an adsorbent consisting of a mixture of a first adsorbent and a second adsorbent.

[0065] It should be noted that the choice of which of the above methods (1)-(3) is to be determined based on the viscosity of the vinyl elastomer resin solution to be adsorbed. If the resin viscosity is high and there are suspended particles, method (1) is preferred. When both the first and second adsorbents are packed in the adsorption column, the problem of column blockage can be effectively prevented. If the solid content of the adsorbent resin solution is low or the viscosity is low at high temperature, method (2) or method (3) can also be used. In particular, since the second adsorbent is used for precision adsorption and the flow channel is small, method (1) is generally used to first use the first adsorbent for coarse adsorption and then use the second adsorbent for precision adsorption, which can achieve better adsorption effect than methods (2) and (3).

[0066] As an optional example, a vinyl elastomer resin solution containing α-diimine ligands is sequentially adsorbed by the first adsorbent and then by the second adsorbent. In this case, metal oxides and / or non-metal oxides exhibit good adsorption effects on metal ions and catalyst ligands in the resin solution due to the active sites formed by the hydroxyl groups on their surface and the van der Waals forces created by their porous structure. Therefore, the vinyl elastomer resin solution is first adsorbed by metal oxides and / or non-metal oxides to remove metal ions and the vast majority of catalyst ligands. Further fine adsorption is then performed using cellulose derivatives (e.g., cellulose acetate). Cellulose derivatives possess a large number of hydroxyl and ester groups, exhibiting excellent coordination and complexation effects for α-diimine ligands. Simultaneously, cellulose derivatives possess high water permeability, selectivity, and good chemical stability. This application utilizes cellulose derivatives for further fine adsorption of catalyst ligands in the vinyl elastomer resin solution, achieving complete removal of catalyst ligands at the ppm level.

[0067] In some embodiments, the continuous decolorization method for the vinyl elastomer resin further includes the step of sequentially loading the first adsorbent and the second adsorbent into an adsorption packing column.

[0068] In some embodiments, the metal oxide includes, but is not limited to, at least one of aluminum oxide (Al2O3), calcium oxide (CaO), and magnesium oxide (MgO).

[0069] In some embodiments, the non-metallic oxide includes, but is not limited to, at least one of silicon oxide, diatomaceous earth, etc.

[0070] As an optional example, the first adsorbent is at least one of a metal oxide and a non-metal oxide.

[0071] In some embodiments, the average particle size of the first adsorbent is 1-20 mm, including but not limited to 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 13 mm, 15 mm or 18 mm.

[0072] As an optional example, the average particle size of the first adsorbent is 1-10 mm, optionally 1-4 mm.

[0073] In the embodiments of this application, if the average particle size of the first adsorbent is too large, the specific surface area of ​​the metal oxide and / or non-metal oxide is too small, resulting in poor adsorption effect and easy saturation, leading to low overall adsorption efficiency. If the average particle size is too small, the vinyl elastomer resin solution containing α-diimine ligands will pass through the adsorption column, resulting in excessive column pressure, which is not conducive to industrial-scale high-flow-rate adsorption and cannot meet the requirements for continuous treatment of high-flow-rate resin solutions.

[0074] It should be noted that the form of the cellulose derivative is not limited in the embodiments of this application, and it can be granular, powdered, or fibrous, etc.

[0075] As an optional example, the cellulose derivative is in powder form. Choosing a powdered cellulose derivative results in a denser packing column and better precision adsorption.

[0076] In some embodiments, the cellulose derivative includes, but is not limited to, at least one of cellulose acetate, cellulose ether, cellulose ester, etc., and may be selected as cellulose acetate.

[0077] In some embodiments, the cellulose acetate contains 53-56 mol% AC, including but not limited to 53.5 mol%, 54 mol%, 54.5 mol%, 55 mol%, or 55.5 mol%. The surface of the cellulose acetate material contains a large number of carboxyl and ester groups, which can form coordination complexes with diimine groups, thereby adsorbing trace amounts of catalyst ligands at the ppm level, achieving complete removal of α-diimine-type catalyst ligands from the resin solution. Choosing cellulose acetate with an AC content of 53-56% results in better removal of α-diimine-type catalyst ligands.

[0078] In the embodiments of this application, the AC content mentioned above refers to the content of acetyl groups (Acetyl Group, chemical formula -COCH3).

[0079] In some embodiments, the second adsorbent is cellulose acetate, which may be selected as cellulose acetate with an AC content of 53-56 mol%.

[0080] Vinyl elastomer resin solutions containing α-diimine ligands have high viscosity at room temperature, which decreases with increasing temperature. Therefore, the adsorption treatment temperature is preferably above 50℃, and more preferably above 70℃. At 70℃, the viscosity of the resin solution is 10–50 mPa·s. Higher temperatures result in lower viscosity and better adsorption, but higher temperatures also lead to greater solvent evaporation. Polyolefin resin solutions typically use alkane compounds as solvents (alkanes are optional), whose saturated vapor pressure increases sharply with temperature. Therefore, the pressure resistance of the equipment must be correspondingly increased. Considering equipment safety and economy, the maximum temperature is generally 200℃, and more preferably 150℃.

[0081] Therefore, in some embodiments, the temperature of the adsorption treatment is 50-200℃, including but not limited to 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃ or 190℃.

[0082] As an alternative example, the temperature of the adsorption treatment is 70-150°C.

[0083] In some embodiments, the continuous decolorization method for the vinyl elastomer resin further includes a step of heating the vinyl elastomer resin solution containing the α-diimine ligand prior to adsorption. This ensures that the vinyl elastomer resin solution containing the α-diimine ligand reaches a temperature comparable to the adsorption treatment temperature before adsorption, thereby ensuring that the resin solution has a low viscosity and subsequently exhibits better adsorption performance, especially when the adsorbent is packed into an adsorption column.

[0084] For example, the temperature of the vinyl elastomer resin solution containing the α-diimine ligand after heating is the temperature of the adsorption treatment, such as 50-200℃, including but not limited to 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃ or 190℃.

[0085] For example, when the solvent in the vinyl elastomer resin solution containing the α-diimine ligand includes an alkane compound, the alkane compound includes, but is not limited to, at least one of hexane (e.g., n-hexane), n-heptane, etc.

[0086] In the embodiments of this application, the pressure of the adsorption treatment should generally be greater than the saturated vapor pressure of the solvent in the vinyl elastomer resin solution containing the α-diimine ligand at the adsorption treatment temperature. That is, if the pressure of the adsorption treatment is x MPa and the saturated vapor pressure of the solvent in the vinyl elastomer resin solution containing the α-diimine ligand at the adsorption temperature is y MPa, then x and y satisfy: x > y. Meeting the above condition with the adsorption treatment pressure ensures that no bubbles are generated during the adsorption process, the adsorbed phase remains in the liquid phase, and the adsorption effect is better.

[0087] Taking hexane as an example, the solvent in a vinyl elastomer resin solution containing α-diimine ligands is 0.1 MPa at 70°C, and 0.24 MPa at 100°C. Therefore, the adsorption treatment pressure for vinyl elastomer resin solutions containing α-diimine ligands can be selected from 0.1 to 0.5 MPa, and more specifically from 0.2 to 0.4 MPa.

[0088] For example, when the solvent in the vinyl elastomer resin solution containing the α-diimine ligand is n-hexane, the adsorption pressure includes, but is not limited to, 0.15 MPa, 0.3 MPa, or 0.35 MPa.

[0089] It should be noted that when the adsorbent is packed into the adsorption column, the vinyl elastomer resin solution containing α-diimine ligands can be supplied with a certain post-pump pressure after being delivered by a melt pump, gear pump or other transfer pump. This post-pump pressure is also the adsorption pressure mentioned above.

[0090] The adsorption effect is related to the adsorption time of the resin solution in the adsorbent. In some embodiments, when the adsorbent is packed in an adsorption column, the adsorption time can be considered as the residence time of the resin solution in the adsorption column. In this case, the resin solution flow rate can be controlled by a transfer pump such as a gear pump or melt pump, thereby controlling the residence time of the resin solution in the adsorption column. To obtain a shorter residence time, the output flow rate of the transfer pump such as the gear pump or melt pump can be increased, thereby shortening the adsorption time and increasing the throughput of the adsorption column per unit time. However, this inevitably leads to a decrease in the adsorption effect. Therefore, the residence time of the resin solution in the adsorption column needs to be considered in combination with the adsorption effect and the processing efficiency. Adsorption residence time is usually expressed as bed volume (BV / h).

[0091] In some embodiments, the adsorption treatment time is 0.5-5 BV / h, including but not limited to 1 BV / h, 1.5 BV / h, 2 BV / h, 2.5 BV / h, 3 BV / h, 3.5 BV / h, 4 BV / h, or 4.5 BV / h. Adsorption treatment times within the above range exhibit good adsorption effects and treatment efficiency.

[0092] As an optional example, the adsorption treatment time is 0.5-3 BV / h.

[0093] In some embodiments, the mass ratio of the first adsorbent to the second adsorbent is (1-10):1, including but not limited to 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, or 9:1. A mass ratio of the first adsorbent to the second adsorbent within the above range can balance precise adsorption and adsorption efficiency. If the content of the second adsorbent is less than 9% of the adsorbent, the precise adsorption effect is poor; if the content of the second adsorbent is greater than 50%, the adsorption resistance is large, the adsorption efficiency is low, and it cannot meet the requirements of large-flow, long-cycle adsorption in industrial applications.

[0094] As an optional example, the mass ratio of the first adsorbent to the second adsorbent is (1-5):1.

[0095] As an alternative example, a continuous decolorization method for vinyl elastomer resins includes the following steps:

[0096] (1) The first adsorbent and the second adsorbent are sequentially loaded into the adsorption packing column to prepare a composite double-layer adsorption packing column.

[0097] (2) After heating the vinyl elastomer resin solution containing α-diimine ligand, it is then added to the adsorption packing column obtained in step (1) by means of a gear pump, melt pump or other transfer pump for adsorption and decolorization.

[0098] In step (2), the heated vinyl elastomer resin solution containing α-diimine ligands is added to the adsorption column by a transfer pump in either a bottom-up or top-down manner. The direction depends on the viscosity of the resin being adsorbed. If the resin viscosity is high and there are suspended particles, a bottom-up adsorption path is preferred to effectively prevent column clogging. In summary, the resin solution adsorption process first passes through the first adsorbent layer and then further through the second adsorbent layer.

[0099] In the embodiments of this application, it is difficult to distinguish the colors of the vinyl elastomer resin solution before and after decolorization. In order to better characterize the decolorization effect after decolorization, the decolorized vinyl elastomer resin solution can be converted into dry resin by flash evaporation in a flash tank (for example, the vinyl elastomer resin solution containing α-diimine ligands after passing through the adsorption packing column in step (2) above can be flash-evaporated in a flash tank to obtain colorless and transparent dry resin) before characterization. It should be particularly emphasized that flash evaporation itself is only a post-processing method for characterizing the decolorization effect after decolorization, and it is not part of the continuous decolorization method of vinyl elastomer resin in the embodiments of this application.

[0100] In some embodiments, the flash evaporation and devolatilization process conditions are: 50–200°C and 0–100 kPa pressure.

[0101] For example, the flash evaporation temperature mentioned above includes, but is not limited to, 75°C, 100°C, 125°C, 150°C, or 175°C.

[0102] For example, the pressure for flash volatilization includes, but is not limited to, 10 kPa, 25 kPa, 40 kPa, 55 kPa, 70 kPa or 85 kPa.

[0103] The continuous decolorization method for vinyl elastomer resins in this application embodiment can bring at least the following beneficial effects:

[0104] 1. By using metal oxides / non-metal oxides and cellulose derivatives as the primary adsorbents and cellulose derivatives as the secondary adsorbents, ppm-level catalyst ligands in vinyl elastomer resin solutions can be removed, ensuring that the treated resin is colorless and transparent, and guaranteeing the aging resistance of the application.

[0105] 2. The process is simple, the raw materials are readily available, and the treatment effect is good. This method has high separation efficiency, high product purity, and all related adsorbents can be regenerated and reused. The whole process is green and environmentally friendly and easy to scale up industrially.

[0106] <Continuous Decolorization System for Vinyl Elastomer Resins>

[0107] The continuous decolorization system for vinyl elastomer resin of this application embodiment can be used for decolorization in the continuous decolorization method of vinyl elastomer resin of this application embodiment. The decolorization system includes an adsorption packing column and a delivery pump. The adsorption packing column is filled with the first adsorbent and the second adsorbent; the delivery pump is connected to a container for storing the vinyl elastomer resin solution containing the α-diimine ligand and the adsorption packing column.

[0108] In some embodiments, the adsorption packing column is sequentially filled with the first adsorbent and the second adsorbent.

[0109] In some embodiments, the delivery pump includes a gear pump or a melt pump, etc.

[0110] For example, in use, a delivery pump adds a heated vinyl elastomer resin solution containing α-diimine ligands into an adsorption packing column from top to bottom or bottom to top. The vinyl elastomer resin solution containing α-diimine ligands flows through the adsorption packing column for adsorption and decolorization.

[0111] For example, to better characterize the decolorization effect, the adsorption packing column can be connected to a flash tank, so that the decolorized vinyl elastomer resin solution can enter the flash tank for flash volatilization to obtain colorless and transparent dry branches, which can then be characterized.

[0112] The continuous decolorization system for vinyl elastomer resins of this application embodiment has at least the beneficial effects of the continuous decolorization method for vinyl elastomer resins of this application embodiment.

[0113] The following non-limiting embodiments further illustrate certain features of the present technology.

[0114] The adsorption packing columns involved in the following embodiments are made of 316L stainless steel and have a volume of 10L.

[0115] The alumina used in the following examples and comparative examples was purchased from Zibo Yinhan Special Alumina Co., Ltd.

[0116] The cellulose acetate used in the following examples and comparative examples was purchased from Nantong cellulose acetate company. The product performance indicators are: powder, AC content of 54%.

[0117] The cellulose ethers involved in the following examples were purchased from Henan Tiansheng Chemical Industry Co., Ltd., and the product performance indicators are: powder form.

[0118] The silica, magnesium oxide, and calcium oxide involved in the following embodiments were all purchased from Zhejiang Manli Nanotechnology Co., Ltd.

[0119] The diatomaceous earth used in the following embodiments was purchased from Zhejiang Kechuang Mining Co., Ltd.

[0120] The catalyst with the structural formula of Formula I involved in Chinese patent application publication number CN119552177A is as follows:

[0121]

[0122] In Equation I, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 Each is independently selected from H, F, Cl, Br, I, NO2, trifluoromethyl, CN, benzyl, diphenylmethyl, C 1-6 Alkyl, C 1-6 The alkoxy groups, X1 and X2, are each independently selected from one of F, Cl, Br, and I.

[0123] Catalysts with the structural formula of formula II:

[0124]

[0125] In Formula II, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 Each is independently selected from H, F, Cl, Br, I, NO2, trifluoromethyl, CN, benzyl, diphenylmethyl, C 1-6 Alkyl, C 1-6 The alkoxy groups, X1 and X2, are each independently selected from one of F, Cl, Br, and I.

[0126] The adsorbed samples underwent colorimetric and PCT aging tests. The test methods are shown below.

[0127] (1) Color

[0128] The adsorbed and flash-evaporated dry resin was extruded and granulated to obtain resin granules with a particle size of 2-3 mm. 20 g of the granules were weighed and added to a test dish. Colorimetric tests were conducted using a colorimeter in transmission mode, in accordance with standard HG / T 3862-2006.

[0129] (2) PCT aging test

[0130] Weigh 10g of resin granules and place them in a 3mm diameter PTFE petri dish. Place the sample in a PCT aging test chamber under the following conditions: 121±0.5℃, relative humidity 99%~100%. After 1 hour, remove the sample and test the initial yellowness value. Continue testing in the chamber for another 48 hours. After the test, remove the sample and cool it at 23±5℃ and relative humidity less than 75% for 2-4 hours. Then, test the yellowness value of the sample according to standard HG / T 3862-2006. The difference in yellowness value before and after PCT aging should be <5.

[0131] Example 1

[0132] The continuous decolorization method for vinyl elastomer resin in this embodiment includes the following steps:

[0133] (1) 8 kg of the first adsorbent and 800 g of the second adsorbent were sequentially loaded into the adsorption packing column to obtain a composite double-layer adsorption packing column.

[0134] The first adsorbent is alumina, the second adsorbent is cellulose acetate, the adsorption packing column is an adsorption packing column with a regulating valve at the bottom, and the height-to-diameter ratio (the ratio of height to inner diameter) of the adsorption packing column is 5:1.

[0135] (2) The vinyl elastomer resin solution containing α-diimine ligand is heated to 80°C (that is, the feed temperature is 80°C and the temperature of subsequent adsorption treatment is also 80°C). Then, it is continuously added from top to bottom to the adsorption packing column obtained in step (1) by a gear pump at a flow rate of 10L / h (that is, the feed flow rate is 10L / h). The pressure of the adsorption packing column (that is, the pressure of adsorption treatment) is controlled to 0.3MPa by the regulating valve at the bottom of the adsorption packing column. After adsorption for 1 hour, 10L of resin solution is obtained.

[0136] The method for obtaining the vinyl elastomer resin solution containing α-diimine ligands is as follows: using an α-diimine catalyst and sesquialuminum as a co-catalyst, and n-hexane as a polymerization solution, branched polyethylene is produced by solution polymerization. The continuous polymerization reaction is carried out at a pressure of 10 kg ethylene and a temperature of 70°C. A small amount of high-purity water is added to the polymerized resin solution to deactivate it and terminate the reaction.

[0137] The α-diimine type catalyst is a catalyst with the structural formula as shown in Formula I, in which R1, R3, R5, R6, and R8 are all CH3, and R2, R4, R7, and R9 are all H. 10 All are benzyl groups, and X1 and X2 are both F.

[0138] The residence time of the vinyl elastomer resin solution containing α-diimine ligand in the adsorption packed column is 1 BV / h.

[0139] Examples 2-10 and Comparative Examples 1-3 are basically the same as Example 1, except that the selection and dosage of some substances and the setting of process parameters are different, as shown in Tables 1, 2 and 3.

[0140] Table 1. Adsorption process parameters for Examples 1-6 and Comparative Examples 1-3, etc.

[0141]

[0142]

[0143] Note: In Table 1, if the amount is 0, it means that the adsorbent is not added. Taking Comparative Example 1 as an example, if the amount of the second adsorbent is 0, it means that the second adsorbent is not loaded in step (1), and only the first adsorbent is loaded.

[0144] Table 2 Adsorption process parameters for Examples 1 and 7-10, etc.

[0145]

[0146] Table 3 shows the selection of functional groups in Formula I of the α-diimine catalysts involved in Examples 1-10 and Comparative Examples 1-3.

[0147]

[0148]

[0149] Example 11 (Compared to Example 1, the feeding method is bottom-up)

[0150] This embodiment is basically the same as embodiment 1, except that:

[0151] In step (2), the feed is continuously added from bottom to top to the adsorption packing column obtained in step (1) by a gear pump at a flow rate of 10 L / h (that is, the feed flow rate is 10 L / h).

[0152] Example 12 (The α-diimine catalyst differs from that in Example 1)

[0153] This embodiment is basically the same as embodiment 1, except that:

[0154] Unlike α-diimine catalysts, the α-diimine catalyst in this embodiment is a catalyst with the structural formula as shown in Formula II. In Formula II, R1, R3, R5, R6, and R8 are all CH3, and R2, R4, R7, and R9 are all H. 10 It is benzyl, and X1 and X2 are both F.

[0155] Example 13 (Compared to Example 1, the two adsorbents are mixed)

[0156] This embodiment is basically the same as embodiment 1, except that:

[0157] In step (1), 8 kg of the first adsorbent and 800 g of the second adsorbent are mixed and then packed into the adsorption packing column.

[0158] Compared with Example 1, Example 14's decolorization method does not rely on the decolorization system of this application.

[0159] The continuous decolorization method for vinyl elastomer resin in this embodiment includes the following steps:

[0160] 10L of vinyl elastomer resin solution containing α-diimine ligand was heated to 80℃, then 8kg of the first adsorbent was added and allowed to stand for adsorption at 80℃ and 0.3MPa for 0.5h. Then 800g of the second adsorbent was added and allowed to stand for adsorption at 80℃ and 0.3MPa for 0.5h. After filtration, 10L of resin solution was obtained.

[0161] The vinyl elastomer resin solution containing α-diimine ligands, the first adsorbent, and the second adsorbent are the same as in Example 1.

[0162] Example 15 (compared to Example 14, dynamic stirring adsorption was used)

[0163] The continuous decolorization method for vinyl elastomer resin in this embodiment includes the following steps:

[0164] 10 L of vinyl elastomer resin solution containing α-diimine ligand was heated to 80 °C, and then 8 kg of the first adsorbent was added and stirred at 80 °C and 0.3 MPa (stirring rate of 200 rpm) for 0.5 h. Then 800 g of the second adsorbent was added and stirred at 80 °C and 0.3 MPa (stirring rate of 200 rpm) for 0.5 h. After filtration, 10 L of resin solution was obtained.

[0165] The vinyl elastomer resin solution containing α-diimine ligands, the first adsorbent, and the second adsorbent are the same as in Example 1.

[0166] Example 16 (Compared to Example 15, the second adsorbent is used first, followed by the first adsorbent)

[0167] This embodiment is basically the same as embodiment 15, except that:

[0168] 10 L of vinyl elastomer resin solution containing α-diimine ligand was heated to 80 °C, and then 800 g of second adsorbent was added and stirred at 80 °C and 0.3 MPa (stirring rate of 200 rpm) for 0.5 h. Then 8 kg of first adsorbent was added and stirred at 80 °C and 0.3 MPa (stirring rate of 200 rpm) for 0.5 h. After filtration, 10 L of resin solution was obtained.

[0169] Example 17 (Compared to Example 16, the two adsorbents are mixed, and the resin solution is not preheated)

[0170] This embodiment is basically the same as embodiment 16, except that:

[0171] First, mix 8 kg of the first adsorbent and 800 g of the second adsorbent evenly, then add them to 10 L of a vinyl elastomer resin solution containing α-diimine ligands. Stir at 80 °C and 0.3 MPa (stirring rate of 200 rpm) for 1 h for adsorption, filter, and obtain 10 L of resin solution.

[0172] Example 18 (Compared to Example 17, a second adsorbent is added to the filtrate after adsorption by the first adsorbent)

[0173] The continuous decolorization method for vinyl elastomer resin in this embodiment includes the following steps:

[0174] 10 L of vinyl elastomer resin solution containing α-diimine ligand was heated to 80 °C, and then 8 kg of the first adsorbent was added and stirred at 80 °C and 0.3 MPa (stirring rate of 200 rpm) for 0.5 h. Then, the solution was filtered for the first time. 800 g of the second adsorbent was added to the filtrate obtained from the first filtration and stirred at 80 °C and 0.3 MPa (stirring rate of 200 rpm) for 0.5 h. Then, the solution was filtered for the second time to obtain 10 L of resin solution.

[0175] The vinyl elastomer resin solution containing α-diimine ligands, the first adsorbent, and the second adsorbent are the same as in Example 1.

[0176] Examples 19-27 are basically the same as Example 12, except that the α-diimine catalyst is a catalyst with the structural formula as shown in Formula II, but the functional groups are different, as shown in Table 4.

[0177] Table 4 shows the selection of functional groups in α-diimine-type catalyst formula II involved in Examples 12, 19-27.

[0178]

[0179] The 10L resin solutions obtained by the decolorization methods of each embodiment and comparative example were respectively fed into a flash evaporator for flash devolatilization to remove n-hexane, yielding colorless and transparent dry resin. The flash devolatilization process conditions were: 10 kPa, 150°C.

[0180] The color and PCT aging properties of the dry resins obtained after flash evaporation and devolatilization in each embodiment and comparative example were tested. The test results are shown in Table 5. Figure 1 As shown.

[0181] Table 5. Test results of color and PCT aging performance of the dry resins obtained from decolorization in each example and comparative example.

[0182]

[0183]

[0184] As can be seen from the data in Table 3, if the vinyl elastomer resin solution of Comparative Example 2 was not decolorized by filler adsorption, the dry resin appeared yellowish (as shown in the attached table). Figure 1 As shown in the figure, the color intensity reached 15, and the difference in yellowness before and after PCT aging reached 10, indicating that the PCT aging was unqualified, which seriously affected the end application. After adsorption and decolorization in Examples 1-27, the color intensity of the resin appearance was significantly reduced, and the color intensity was controlled within 1, and the PCT aging index was qualified. Comparative Examples 1 and 3 contained only alumina or cellulose acetate as adsorbents, and their decolorization effects were not good. After decolorization, the resin surface still showed a pale yellow color, and the PCT aging data was unqualified.

[0185] In summary, the decolorization method of this application has a good decolorization effect on vinyl elastomer resin solutions prepared with α-diimine type catalysts, and can be applied to its continuous preparation process, showing good application prospects.

[0186] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0187] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0188] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A continuous decolorization method for vinyl elastomer resins, characterized in that, include: The vinyl elastomer resin solution containing α-diimine ligands was subjected to adsorption treatment; The adsorbent used in the adsorption treatment includes a first adsorbent and a second adsorbent. The first adsorbent includes at least one of a metal oxide and a non-metal oxide. The second adsorbent includes a cellulose derivative. The metal oxide includes at least one of aluminum oxide, calcium oxide, and magnesium oxide; The non-metallic oxide includes at least one of silicon dioxide and diatomaceous earth; The cellulose derivatives include at least one of cellulose acetate, cellulose ether, and cellulose ester.

2. The continuous decolorization method for vinyl elastomer resin according to claim 1, characterized in that, The adsorption treatment includes: A vinyl elastomer resin solution containing α-diimine ligands is sequentially adsorbed by the first adsorbent and then by the second adsorbent.

3. The continuous decolorization method for vinyl elastomer resin according to claim 1, characterized in that, The adsorption treatment includes: A vinyl elastomer resin solution containing an α-diimine ligand is sequentially adsorbed by the second adsorbent and then by the first adsorbent.

4. The continuous decolorization method for vinyl elastomer resin according to any one of claims 1 to 3, characterized in that, The cellulose derivative is in powder form; And / or, the cellulose derivative is cellulose acetate; And / or, the pressure of the adsorption treatment is x MPa, the saturated vapor pressure of the solvent in the vinyl elastomer resin solution containing the α-diimine ligand at the adsorption treatment temperature is y MPa, and x and y satisfy: x > y.

5. The continuous decolorization method for vinyl elastomer resin according to claim 4, characterized in that, The cellulose derivative is cellulose acetate with an AC content of 53-56 mol%.

6. The continuous decolorization method for vinyl elastomer resin according to any one of claims 1 to 3, characterized in that, The mass ratio of the first adsorbent to the second adsorbent is (1-10):1; And / or, the average particle size of the first adsorbent is 1-20 mm; And / or, the temperature of the adsorption treatment is 50-200℃; And / or, the pressure of the adsorption treatment is 0.1-0.5 MPa; And / or, the adsorption treatment time is 0.5-5 BV / h.

7. The continuous decolorization method for vinyl elastomer resin according to claim 6, characterized in that, The mass ratio of the first adsorbent to the second adsorbent is (1-5):1; And / or, the particle size range of the first adsorbent is 1-10 mm; And / or, the temperature of the adsorption treatment is 70-150°C; And / or, the pressure of the adsorption treatment is 0.2-0.4 MPa; And / or, the adsorption treatment time is 0.5-3 BV / h.

8. The continuous decolorization method for vinyl elastomer resin according to any one of claims 1 to 3, characterized in that, The solvent in the vinyl elastomer resin solution containing α-diimine ligands includes alkane compounds; And / or, the continuous decolorization method for the vinyl elastomer resin further includes the step of heating the vinyl elastomer resin solution containing the α-diimine ligand prior to the adsorption treatment; And / or, the continuous decolorization method for the vinyl elastomer resin further includes the step of sequentially loading the first adsorbent and the second adsorbent into an adsorption packing column.

9. The continuous decolorization method for vinyl elastomer resin according to claim 8, characterized in that, The vinyl elastomer resin solution containing α-diimine ligands is pressurized to 0.2~0.5MPa and heated to a temperature of 50-200℃.

10. A continuous decolorization system for vinyl elastomeric resins, applied to the continuous decolorization method for vinyl elastomeric resins as described in any one of claims 1 to 9, characterized in that, include: An adsorption packed column, wherein the adsorption packed column is filled with the first adsorbent and the second adsorbent; A delivery pump is connected to a container for storing the vinyl elastomer resin solution containing the α-diimine ligand and the adsorption packing column.

Images