Plastic deinking agent as well as preparation method and application thereof

Abstract

The invention discloses a plastic deinking agent and a preparation method and application thereof, and belongs to the technical field of deinking agents. The plastic deinking agent is composed of an organic solvent, a surfactant and water; the organic solvent is composed of an ether solvent, an ester solvent, a ketone solvent and an amide solvent; the surface active agent is prepared from a polysorbate surface active agent and a polyoxyethylene surface active agent. The plastic deinking agent provided by the invention has the effects of emulsifying, wetting, dispersing and stripping printing ink on plastic, can effectively destroy the adhesive force of the printing ink on the plastic, and can recycle the printing ink on a plastic cup or clean dirt on the printing ink, and the stripped printing ink cannot be deposited on the plastic cup. The plastic deinking agent disclosed by the invention has the characteristics of low foam, easiness in cleaning, recyclability and high cost performance.

Description

Technical Field

[0001] This invention belongs to the field of deinking agent technology, and particularly relates to a plastic deinking agent, its preparation method and application. Background Technology

[0002] Among the many inventions of the 20th century, plastics stood out due to their low cost and superior performance, leading to their rapid and widespread adoption. While the rapid growth of the plastics industry has posed a serious challenge to the environment, it is also considered a crucial renewable resource. Recycling waste plastics helps reduce white pollution, while simultaneously creating economic benefits through resource reuse, thus promoting sustainable development.

[0003] The recycling process of waste plastics mainly includes four steps: washing, crushing, granulation, and reprocessing. Washing, as the first step in the entire process, is crucial for ensuring the quality of the final product. If washing is skipped and crushing and granulation are carried out directly, the resulting products are often dull in color, of low quality, and have a rough surface. This will greatly limit their application range, reduce their market value, and thus hinder the healthy development of the waste plastic recycling industry. Therefore, thorough washing is a key step in increasing the added value of recycled plastics and expanding their application areas. Currently, milk tea cups on the market are printed with a large number of patterns and texts, and the inks used for these patterns and texts are highly adhesive and difficult to remove manually or by simple physical methods. If the ink on the surface of the cup is not effectively removed during the plastic recycling process, the resulting plastic granules will be dark or black, resulting in low prices and meager profits. Although recycling can be achieved by selecting only the white areas for cutting and granulation, this method is not only time-consuming and labor-intensive but also greatly reduces production efficiency. In contrast, if the ink on the plastic can be thoroughly washed off before granulation, the resulting granules will be white, significantly increasing their market price and thus greatly improving the profitability of manufacturers. However, currently available plastic deinking agents perform poorly when dealing with highly adhesive inks and can damage the plastic material during the deinking process. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a plastic deinking agent, its preparation method, and its application. The plastic deinking agent of this invention possesses the functions of emulsifying, wetting, dispersing, and stripping ink, effectively weakening the adhesion strength between ink and plastic, thereby thoroughly removing ink or stains from the plastic surface and ensuring that the stripped ink does not re-adhere to the plastic surface. Furthermore, the plastic deinking agent of this invention has low-foaming properties, is easy to rinse, can be used at room temperature and pressure, and can be recycled, exhibiting good economic efficiency and practicality.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a plastic deinking agent, which is composed of an organic solvent, a surfactant, and water;

[0007] The organic solvent is composed of ether solvents, ester solvents, ketone solvents and amide solvents;

[0008] The surfactant is composed of polysorbate surfactants and polyoxyethylene surfactants.

[0009] The principle of this invention: The ether solvents used in this invention are environmentally friendly co-solvents with good solubility and environmental properties. They form a composite solvent system with the amide solvents used in this invention. The former targets polar inks (such as water-based inks), while the latter dissolves non-polar inks (such as acrylates in UV inks). Broad-spectrum deinking is achieved through polarity complementarity. Furthermore, because it does not swell on polypropylene (PP) plastic, it avoids damage to the substrate. The ester solvents used in this invention, as detergents, have low surface tension properties that allow them to quickly wet the plastic surface, disrupting ink adhesion. They rapidly penetrate along the ink-plastic interface, effectively breaking down ink adhesion and creating favorable conditions for subsequent solvent dissolution of the ink. Simultaneously, the ketone solvents used in this invention have good solubility and low volatility, helping to maintain the concentration stability of the deinking agent during the cleaning process, forming a synergistic "wetting-dissolving-stabilizing" mechanism with the ester solvents. Polysorbate surfactants are highly hydrophilic and can emulsify with the ink particles stripped by the ester and ketone solvents, forming a stable microemulsion. This disperses the detached ink contaminants in water, preventing ink redeposition. The above-mentioned raw materials are carefully formulated to specifically deink plastics. The plastic deinking agent of this invention has low-foaming properties, is easy to clean, and has high cleaning efficiency. This plastic deinking agent effectively removes ink from the surface of polypropylene (PP) and polyethylene (PE) plastics, inks that are often difficult to remove with conventional deinking agents. The ink removal rate of this plastic deinking agent is over 90%. The raw materials of this plastic deinking agent do not contain strong alkaline substances, and the solution is neutral, therefore it will not have any adverse effects on the quality of equipment or substrates. When used in combination with alkaline substances, its deinking effect will be even more significant.

[0010] Furthermore, the mass ratio of the organic solvent to the surfactant is (3-7):1;

[0011] The mass of the water is 5 to 10 times the total mass of the organic solvent and surfactant.

[0012] Furthermore, the ether solvent is selected from one of propylene glycol methyl ether (DPM), dipropylene glycol dimethyl ether (DMM), diethylene glycol ethyl ether (DE), and dipropylene glycol diethyl ether (DPG).

[0013] Furthermore, the ester solvent is selected from one of n-butyl acetate, isobutyl acetate, sec-butyl acetate, and tert-butyl acetate.

[0014] Furthermore, the ketone solvent is selected from one of acetone, cyclohexanone, isoflurane, methylcyclohexanone, and isopropylidene acetone.

[0015] Furthermore, the amide solvent is selected from N-methylpyrrolidone and N-butylpyrrolidone.

[0016] Furthermore, the polysorbate surfactant is selected from one of Tween 20, Tween 40, Tween 60 and Tween 80;

[0017] And / or, the polyoxyethylene surfactant is selected from one of fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, polyol polyoxyethylene ether fatty acid esters, and fatty acid methyl ester ethoxylates.

[0018] In this invention, fatty alcohol polyoxyethylene ether in the ether solvent has good detergency, emulsifying power and foaming properties. When compounded with Tween 80, it forms mixed micelles. By increasing the solubilization space of the micelles for ink, it significantly improves the overall system's ability to remove residual ink. The two work together to enhance the dispersion and suspension effect of ink, further ensuring the cleanliness of the plastic surface after deinking.

[0019] The present invention also provides a method for preparing the above-mentioned plastic deinking agent: mixing an organic solvent with a surfactant, adding water, and stirring until completely dissolved to obtain the plastic deinking agent.

[0020] The present invention also provides the application of the above-mentioned plastic deinking agent in plastic deinking.

[0021] The present invention also provides a method for deinking plastic: the plastic is immersed in the above-mentioned plastic deinking agent, stirred to deink, washed with clean water to rinse away the residual plastic deinking agent, and then dried.

[0022] In the plastic deinking method of the present invention, the plastic deinking agent can also be used in combination with an alkali to enhance the deinking effect.

[0023] For example, the agitation deinking is carried out in a high-speed friction machine with an agitation speed of 1000 r / min.

[0024] Compared with the prior art, the present invention has the following advantages and technical effects:

[0025] The plastic deinking agent provided by this invention has emulsifying, wetting, dispersing, and peeling effects on inks on plastics (such as PP and PE plastics). It can effectively destroy the adhesion of inks to plastics, and can recover inks from plastic cups (such as milk tea cups) or clean away dirt from them. Moreover, the peeled ink will not re-deposit on the plastic cup. The plastic deinking agent of this invention has low foaming properties, is easy to clean, can be recycled, and has a high cost-performance ratio. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1 The deinking effect of the plastic deinking agent in Example 1 is shown with and without caustic soda flakes. Detailed Implementation

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0029] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0031] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0032] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0033] An embodiment of the present invention provides a plastic deinking agent, which is composed of an organic solvent, a surfactant and water;

[0034] Organic solvents consist of ether solvents, ester solvents, ketone solvents, and amide solvents;

[0035] The surfactant is composed of polysorbate surfactants and polyoxyethylene surfactants.

[0036] In embodiments of the present invention, the mass ratio of organic solvent to surfactant is (3-7):1, preferably 4:1;

[0037] The mass of water is 5 to 10 times the total mass of the organic solvent and surfactant, preferably 10 times the total mass of the organic solvent and surfactant. Within this range, the deinking efficiency of the plastic deinking agent can be maintained while maximizing solvent savings, achieving better overall benefits.

[0038] In embodiments of the present invention, the mass ratio of ether solvent, ester solvent, ketone solvent and amide solvent is (4-6):(2-4):(2-4):(4-6), preferably 5:3:3:5.

[0039] In embodiments of the present invention, the mass ratio of polysorbate surfactant to polyoxyethylene surfactant is (1-2):1, preferably 1:1.

[0040] In embodiments of the present invention, the ether solvent is selected from one of propylene glycol methyl ether (DPM), dipropylene glycol dimethyl ether (DMM), diethylene glycol ethyl ether (DE), and dipropylene glycol diethyl ether (DPG), preferably DPG. This is because DPG combines low surface tension, moderate boiling point, and high hydrophobicity, effectively wetting the polypropylene (PP) surface and penetrating to the ink interface, thereby disrupting adhesion. Simultaneously, DPG exhibits low swelling of the PP substrate, avoiding damage to the plastic body. Its high flash point, low toxicity, and biodegradability further ensure process safety and environmental friendliness, meeting the design requirements of a green deinking agent.

[0041] In embodiments of the present invention, the ester solvent is selected from one of n-butyl acetate, isobutyl acetate, sec-butyl acetate, and tert-butyl acetate, preferably n-butyl acetate. This is because n-butyl acetate has a higher boiling point and a slower evaporation rate, allowing it to remain on the plastic surface for a longer period, fully penetrating and acting, and is less prone to rapid evaporation that could cause changes in the concentration of the deinking agent. Due to its low surface tension, n-butyl acetate can quickly spread and wet the hydrophobic PP plastic surface, creating conditions for the subsequent solvent (such as N-methylpyrrolidone) to completely dissolve the ink.

[0042] In embodiments of the present invention, the ketone solvent is selected from acetone, cyclohexanone, isophorone, methylcyclohexanone, and isopropylidene acetone, preferably isophorone. This is because isophorone has a high boiling point and low volatility, which can effectively maintain the concentration stability of the deinking agent system and ensure its stable performance in single and cyclic use. Compared with highly volatile solvents such as acetone, isophorone has a milder and more controllable swelling effect on polypropylene (PP) plastics, which can avoid substrate embrittlement or stress cracking and protect the integrity of the plastic body. At the same time, its high flash point significantly improves the safety of the process, especially suitable for high-speed mechanical stirring deinking scenarios, fundamentally reducing the risk of combustion or explosion.

[0043] In embodiments of the present invention, the amide solvent is selected from N-methylpyrrolidone (NMP) and N-butylpyrrolidone, preferably N-methylpyrrolidone. This is because N-methylpyrrolidone possesses both strong polarity and a high boiling point, exhibiting excellent solubility for polar inks (such as acrylates, polyurethanes, and epoxy resins), effectively disrupting cross-linked structures, and is a key component for achieving efficient deinking. The high boiling point of N-methylpyrrolidone ensures the concentration stability of the working solution during the process. When combined with DPG, which has strong hydrophobicity, and isoflurane, which is moderately polar, NMP, as the main strongly polar solvent, together constructs a broad-spectrum solvent system, achieving synergistic dissolution and stripping of inks with complex compositions, significantly improving deinking efficiency and applicability.

[0044] In embodiments of the present invention, the polysorbate surfactant is selected from Tween 20, Tween 40, Tween 60, and Tween 80, preferably Tween 80. This is because Tween 80 has excellent oleophilicity, which can effectively capture and emulsify ink resin particles peeled from the PP plastic surface, forming a stable microemulsion and preventing ink redeposition. Simultaneously, when Tween 80 is compounded with fatty alcohol polyoxyethylene ether, it can form mixed micelles, synergistically enhancing the solubilization and suspending ability of oily substances, significantly improving ink dispersion stability, and ensuring a long-lasting clean surface after deinking.

[0045] In embodiments of the present invention, the polyoxyethylene surfactant is selected from one of fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, polyol polyoxyethylene ether fatty acid esters, and fatty acid methyl ester ethoxylates, preferably fatty alcohol polyoxyethylene ethers. This is because fatty alcohol polyoxyethylene ethers have good biodegradability and environmental friendliness, avoiding the ecotoxicity risks of alkylphenol polyoxyethylene ethers. The hydrophilic-lipophilic balance (HLB) of fatty alcohol polyoxyethylene ethers is adjustable, which can effectively wet the PP surface and emulsify the ink. When fatty alcohol polyoxyethylene ethers are compounded with Tween 80, they can form more stable mixed micelles, synergistically enhancing the solubilization and suspending ability of ink resins, effectively preventing the redeposition of stripped ink, thereby ensuring the cleanliness and whiteness of the surface after deinking, while also having the process advantages of low foaming and easy rinsing.

[0046] The embodiments of the present invention also provide a method for preparing the above-mentioned plastic deinking agent: mixing an organic solvent with a surfactant, adding water, and stirring until completely dissolved to obtain the plastic deinking agent.

[0047] Embodiments of the present invention also provide the application of the above-mentioned plastic deinking agent in plastic deinking.

[0048] For example, the plastic is selected from polypropylene (PP) plastic and polyethylene (PE) plastic.

[0049] An embodiment of the present invention also provides a method for deinking plastic: the plastic is immersed in the above-mentioned plastic deinking agent, stirred and deinked in a high-speed friction machine, washed with clean water, and then dried.

[0050] This invention involves mixing organic solvents (ether solvents, ester solvents, ketone solvents, amide solvents) with surfactants (polysorbate surfactants, polyoxyethylene surfactants), adding 5-10 times the weight of water, and stirring until completely dissolved to prepare a plastic deinking agent. The plastic is then immersed in the deinking agent, stirred to remove ink, washed with clean water, and dried for recycling. The plastic deinking agent of this invention possesses emulsifying, wetting, dispersing, and ink-removing functions, effectively weakening the adhesion strength between ink and plastic, thereby thoroughly removing surface ink or stains and ensuring that the removed ink does not re-adhere to the plastic surface. Furthermore, the plastic deinking agent of this invention has low-foaming properties, is easy to rinse, can be used at room temperature and pressure, and can be recycled, exhibiting good economic efficiency and practicality.

[0051] In the plastic deinking method of the present invention, the plastic deinking agent can also be used in combination with an alkaline substance to enhance the deinking effect. When the plastic deinking agent of the present invention is used in combination with an alkali to deink plastic, the specific method is as follows: First, an alkaline substance is added to the plastic deinking agent to adjust the pH of the solution to 13-14, obtaining an alkaline deinking agent solution; then, the plastic is immersed in the above alkaline deinking agent solution for 2 hours. After immersion, the plastic is transferred to a high-speed friction machine (speed 1000 r / min) and subjected to stirring and deinking treatment with the alkaline deinking agent solution; then, the surface of the plastic is washed with clean water, and finally dried.

[0052] For example, the alkaline substance is caustic soda flakes.

[0053] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0054] All raw materials used in the embodiments of this invention were purchased commercially. As an example, dipropylene glycol diethyl ether was purchased from Hubei Meibei New Materials Co., Ltd., N-methylpyrrolidone was purchased from Guangdong Yuemei Chemical Co., Ltd., butyl acetate was purchased from Shanghai Titan Technology Co., Ltd., isoflurone was purchased from Tianjin Zhonghe Shengtai Chemical Co., Ltd., and fatty alcohol polyoxyethylene ether was purchased from Guangzhou Tongyang Chemical Co., Ltd.

[0055] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0056] The technical solution of the present invention will be further illustrated by the following embodiments.

[0057] Example 1

[0058] A method for preparing a plastic deinking agent, comprising the following steps:

[0059] Dipropylene glycol diethyl ether, n-butyl acetate, isoflurane, and N-methylpyrrolidone were mixed in a mass ratio of 5:3:3:5 and stirred for 10 minutes to obtain an organic solvent. Tween 80 and fatty alcohol polyoxyethylene ether were mixed in a mass ratio of 1:1 and stirred for 10 minutes to obtain a surfactant. The organic solvent and surfactant were mixed in a mass ratio of 4:1, and 10 times their mass of water were added. The mixture was stirred until completely dissolved to obtain a plastic deinking agent.

[0060] The steps for deinking plastics using the aforementioned plastic deinking agent are as follows:

[0061] Soak polypropylene (PP) plastic in the above-mentioned plastic deinking agent for 2 hours, then put the plastic into a high-speed friction machine for stirring (speed: 1000 r / min), continuously clean it with plastic deinking agent for 1 hour, and finally rinse it with clean water for 30 minutes to completely remove the residual deinking agent components. Dry it to obtain deinked plastic.

[0062] Example 2

[0063] A method for preparing a plastic deinking agent, comprising the following steps:

[0064] Dipropylene glycol diethyl ether, n-butyl acetate, isoflurane, and N-methylpyrrolidone were mixed in a mass ratio of 5:4:2:5 and stirred for 10 minutes to obtain an organic solvent. Tween 80 and fatty alcohol polyoxyethylene ether were mixed in a mass ratio of 1:1 and stirred for 10 minutes to obtain a surfactant. The organic solvent and surfactant were mixed in a mass ratio of 4:1, and 10 times their mass of water were added. The mixture was stirred until completely dissolved to obtain a plastic deinking agent.

[0065] The steps for deinking plastics using the aforementioned plastic deinking agent are as follows:

[0066] Soak the PP plastic in plastic deinking agent for 2 hours, then put the plastic into a high-speed friction machine for stirring (speed: 1000r / min), and continuously clean it with plastic deinking agent for 1.2 hours. Finally, rinse with clean water for 30 minutes to completely remove the residual deinking agent components. Dry to obtain deinked plastic.

[0067] Example 3

[0068] A method for preparing a plastic deinking agent, comprising the following steps:

[0069] Dipropylene glycol diethyl ether, n-butyl acetate, isoflurane, and N-methylpyrrolidone were mixed in a mass ratio of 3:1:1:3 and stirred for 10 minutes to obtain an organic solvent. Tween 80 and fatty alcohol polyoxyethylene ether were mixed in a mass ratio of 1:1 and stirred for 10 minutes to obtain a surfactant. The organic solvent and surfactant were mixed in a mass ratio of 4:1, and 10 times their mass of water were added. The mixture was stirred until completely dissolved to obtain a plastic deinking agent.

[0070] The steps for deinking plastics using the aforementioned plastic deinking agent are as follows:

[0071] Soak the PP plastic in plastic deinking agent for 2 hours, then put the plastic into a high-speed friction machine for stirring (speed: 1000r / min), and continuously clean it with plastic deinking agent for 1.5 hours. Finally, rinse it with clean water for 30 minutes to completely remove the residual deinking agent components. Dry it to obtain deinked plastic.

[0072] Example 4

[0073] A method for preparing a plastic deinking agent, comprising the following steps:

[0074] Dipropylene glycol diethyl ether, n-butyl acetate, isoflurane, and N-methylpyrrolidone were mixed in a mass ratio of 3:1:2:2 and stirred for 10 min to obtain an organic solvent. Tween 80 and fatty alcohol polyoxyethylene ether were mixed in a mass ratio of 1:1 and stirred for 10 min to obtain a surfactant. The organic solvent and surfactant were mixed in a mass ratio of 4:1, and 10 times their mass of water were added. The mixture was stirred until completely dissolved to obtain a plastic deinking agent.

[0075] The steps for deinking plastics using the aforementioned plastic deinking agent are as follows:

[0076] Soak the PP plastic in plastic deinking agent for 2 hours, then put the plastic into a high-speed friction machine for stirring (speed: 1000r / min), and continue to clean it with plastic deinking agent for 2 hours. Finally, rinse it with clean water for 30 minutes to completely remove the residual deinking agent components. Dry it to obtain deinked plastic.

[0077] Example 5

[0078] A method for preparing a plastic deinking agent, comprising the following steps:

[0079] Dipropylene glycol diethyl ether, n-butyl acetate, isoflurane, and N-methylpyrrolidone were mixed in a mass ratio of 6:3:3:4 and stirred for 10 minutes to obtain an organic solvent. Tween 80 and fatty alcohol polyoxyethylene ether were mixed in a mass ratio of 1:1 and stirred for 10 minutes to obtain a surfactant. The organic solvent and surfactant were mixed in a mass ratio of 4:1, and 10 times their mass of water were added. The mixture was stirred until completely dissolved to obtain a plastic deinking agent.

[0080] The steps for deinking plastics using the aforementioned plastic deinking agent are as follows:

[0081] Soak PP plastic in plastic deinking agent for 2 hours, then put the plastic into a high-speed friction machine for stirring (speed: 1000r / min), and continuously clean it with plastic deinking agent for 2.5 hours. Finally, rinse with clean water for 30 minutes to completely remove residual deinking agent components, and dry to obtain deinked plastic.

[0082] Example 6

[0083] A method for preparing a plastic deinking agent, comprising the following steps:

[0084] Dipropylene glycol diethyl ether, n-butyl acetate, isoflurane, and N-methylpyrrolidone were mixed in a mass ratio of 2:1:1:2 and stirred for 10 minutes to obtain an organic solvent. Tween 80 and fatty alcohol polyoxyethylene ether were mixed in a mass ratio of 2:1 and stirred for 10 minutes to obtain a surfactant. The organic solvent and surfactant were mixed in a mass ratio of 4:1, and 10 times their mass of water were added. The mixture was stirred until completely dissolved to obtain a plastic deinking agent.

[0085] The steps for deinking plastics using the aforementioned plastic deinking agent are as follows:

[0086] Soak PP plastic in plastic deinking agent for 2 hours, then put the plastic into a high-speed friction machine for stirring (speed: 1000r / min), continuously clean it with plastic deinking agent for 3 hours, and finally rinse it with clean water for 30 minutes to completely remove the residual deinking agent components. Dry it to obtain deinked plastic.

[0087] The plastic deinking agents prepared in Examples 1-6 of this invention were applied to the recycling of waste plastics. A comparative experiment was conducted using six commercially available deinking agents (Super Strong JX-463, Fullercare QXJ-HL002, Precision JD-518, Shanghai Pinlei ZT, Aigre C602, and FANUC HN338). The waste plastic recycling process specifically includes the following steps: 20 kg of waste PP plastic was soaked in 60 L of deinking agent for 2 hours, then transferred to a high-speed friction machine and stirred at 1000 r / min for 1 hour, during which time it was continuously cleaned with deinking agent; finally, it was rinsed with clean water for 30 minutes to completely remove residual deinking agent components, and dried to obtain deinked plastic.

[0088] The deinking agent was either the plastic deinking agent prepared in Examples 1-6 of this invention or one of the six commercially available deinking agents. When more than 95% of the ink on the surface of the waste plastic was removed, the plastic was retrieved, and the deinking effect was determined by statistically analyzing the ink removal time. The experimental results are shown in Table 1.

[0089] Table 1. Comparison of the deinking and ink removal experimental results of the present invention and six commercially available plastic deinking agents.

[0090]

[0091]

[0092] As can be seen from Table 1, under the same conditions, Example 1 has a shorter deinking time than commercially available deinking agents, indicating that the plastic deinking agent provided by the present invention has a good ink cleaning effect.

[0093] Example 7

[0094] A method for preparing a plastic deinking agent, comprising the following steps:

[0095] Propylene glycol methyl ether, isobutyl acetate, acetone, and N-butylpyrrolidone were mixed in a mass ratio of 5:3:3:5 and stirred for 10 min to obtain an organic solvent. Tween 20 and alkylphenol polyoxyethylene ether were mixed in a mass ratio of 1:1 and stirred for 10 min to obtain a surfactant. The organic solvent and surfactant were mixed in a mass ratio of 4:1, and 10 times their mass of water were added. The mixture was stirred until completely dissolved to obtain a plastic deinking agent.

[0096] The steps for deinking plastics using the aforementioned plastic deinking agent are as follows:

[0097] Soak 20 kg of waste polyethylene (PE) plastic in the above 60 L plastic deinking agent for 2 hours. Then, put the plastic into a high-speed friction machine for stirring (speed: 1000 r / min) and continuously clean it with plastic deinking agent for 1 hour. Finally, rinse with clean water for 30 minutes to completely remove the residual deinking agent components. Dry to obtain deinked plastic.

[0098] When more than 95% of the ink on the surface of the waste plastic has been removed, the plastic should be taken out. The ink removal time is 0.6 hours.

[0099] Example 8

[0100] A method for preparing a plastic deinking agent, comprising the following steps:

[0101] Dipropylene glycol dimethyl ether, sec-butyl acetate, cyclohexanone, and N-methylpyrrolidone were mixed in a mass ratio of 4:3:4:6 and stirred for 10 min to obtain an organic solvent. Tween 40 and polyol polyoxyethylene ether fatty acid ester were mixed in a mass ratio of 1:1 and stirred for 10 min to obtain a surfactant. The organic solvent and surfactant were mixed in a mass ratio of 3:1, and 10 times their mass of water were added. The mixture was stirred until completely dissolved to obtain a plastic deinking agent.

[0102] The steps for deinking plastics using the aforementioned plastic deinking agent are as follows:

[0103] Soak 20 kg of waste PE plastic in the above 60 L plastic deinking agent for 2 hours, then put the plastic into a high-speed friction machine for stirring (speed: 1000 r / min), continuously clean it with plastic deinking agent for 1 hour, and finally rinse it with clean water for 30 minutes to completely remove the residual deinking agent components. Dry it to obtain deinked plastic.

[0104] When more than 95% of the ink on the surface of the waste plastic has been removed, the plastic should be taken out. The ink removal time is 0.8 hours.

[0105] It should be noted that, due to the inherent material properties, ink on PE plastic is generally easier to remove than ink on PP plastic.

[0106] Example 9

[0107] A method for preparing a plastic deinking agent, comprising the following steps:

[0108] Diethylene glycol ethyl ether, tert-butyl acetate, methylcyclohexanone, and N-methylpyrrolidone were mixed in a mass ratio of 6:2:3:4 and stirred for 10 min to obtain an organic solvent. Tween 60 and fatty acid methyl ester ethoxylate were mixed in a mass ratio of 1:1 and stirred for 10 min to obtain a surfactant. The organic solvent and surfactant were mixed in a mass ratio of 7:1, and 5 times their mass of water were added. The mixture was stirred until completely dissolved to obtain a plastic deinking agent.

[0109] The steps for deinking plastics using the aforementioned plastic deinking agent are as follows:

[0110] Soak 20 kg of waste PP plastic in the above 60 L plastic deinking agent for 2 hours, then put the plastic into a high-speed friction machine for stirring (speed: 1000 r / min), continuously clean it with plastic deinking agent for 1 hour, and finally rinse it with clean water for 30 minutes to completely remove the residual deinking agent components. After drying, the deinked plastic can be obtained.

[0111] When more than 95% of the ink on the surface of the waste plastic has been removed, the plastic should be taken out. The ink removal time is 1 hour.

[0112] Example 10

[0113] A method for preparing a plastic deinking agent, comprising the following steps:

[0114] Dipropylene glycol diethyl ether, n-butyl acetate, isopropylidene acetone, and N-methylpyrrolidone were mixed in a mass ratio of 4:4:3:6 and stirred for 10 min to obtain an organic solvent. Tween 60 and fatty acid methyl ester ethoxylate were mixed in a mass ratio of 2:1 and stirred for 10 min to obtain a surfactant. The organic solvent and surfactant were mixed in a mass ratio of 3:1, and 5 times their mass of water were added. The mixture was stirred until completely dissolved to obtain a plastic deinking agent.

[0115] The steps for deinking plastics using the aforementioned plastic deinking agent are as follows:

[0116] Soak 20 kg of waste PP plastic in the above 60 L plastic deinking agent for 2 hours, then put the plastic into a high-speed friction machine for stirring (speed: 1000 r / min), continuously clean it with plastic deinking agent for 1 hour, and finally rinse it with clean water for 30 minutes to completely remove the residual deinking agent components. After drying, the deinked plastic can be obtained.

[0117] When more than 95% of the ink on the surface of the waste plastic has been removed, the plastic should be taken out. The ink removal time is 1.2 hours.

[0118] Comparative Example 1

[0119] Same as Example 1, except that dipropylene glycol diethyl ether was not added when preparing the organic solvent.

[0120] The plastic was de-inked using the above-mentioned plastic de-inking agent, following the same steps as in Example 10. When more than 95% of the ink on the surface of the waste plastic was removed, the plastic was taken out. The de-inking time was 2 hours.

[0121] Dipropylene glycol diethyl ether can help improve the wetting and penetration efficiency of the deinking system on PP, synergistically optimize the solvent spectrum to enhance ink dissolution and stripping capabilities, and help maintain stable system concentration. Without this component, the wetting and penetration of the system slows down, the synergistic effect of ink dissolution and stripping is weakened, the synergistic effect of each component is limited, resulting in a longer deinking time.

[0122] Comparative Example 2

[0123] Same as Example 1, except that n-butyl acetate was not added when preparing the organic solvent.

[0124] The plastic was de-inked using the above-mentioned plastic de-inking agent, following the same steps as in Example 10. When more than 95% of the ink on the surface of the waste plastic was removed, the plastic was taken out. The de-inking time was 2.5 hours.

[0125] Butyl acetate can remain on the PP surface for a long time to fully wet and penetrate, creating conditions for ink dissolution and maintaining stable system concentration. Without the addition of butyl acetate, the system suffers from insufficient wetting and penetration, easy concentration fluctuations, decreased ink dissolution efficiency, and prolonged deinking time.

[0126] Comparative Example 3

[0127] Same as Example 1, except that isoflurone was not added when preparing the organic solvent.

[0128] The plastic was de-inked using the above-mentioned plastic de-inking agent, following the same steps as in Example 10. When more than 95% of the ink on the surface of the waste plastic was removed, the plastic was taken out. The de-inking time was 1.8 hours.

[0129] Isoflurone can maintain a stable deinking agent concentration, gently protect the PP substrate, and enhance the synergistic effect of the solvent. Without this component, the system concentration is prone to fluctuations, the solvent synergistic effect is weakened, the ink stripping efficiency decreases, and the deinking time is prolonged.

[0130] Comparative Example 4

[0131] Same as Example 1, except that N-methylpyrrolidone was not added when preparing the organic solvent.

[0132] The plastic was de-inked using the above-mentioned plastic de-inking agent, following the same steps as in Example 10. When more than 95% of the ink on the surface of the waste plastic was removed, the plastic was taken out. The de-inking time was 2 hours.

[0133] N-Methylpyrrolidone is key to dissolving polar inks and disrupting their cross-linked structures. It also synergistically constructs a broad-spectrum solvent system and stabilizes the concentration. Without this component, the system loses its core dissolving component, the solvent synergy breaks down, ink stripping efficiency drops significantly, and deinking time is prolonged.

[0134] Comparative Example 5

[0135] Same as Example 1, except that Tween 80 was not added when preparing the surfactant. In this comparative example, the mass of fatty alcohol polyoxyethylene ether is the sum of the masses of Tween 80 and fatty alcohol polyoxyethylene ether in Example 1.

[0136] The plastic was de-inked using the above-mentioned plastic de-inking agent, following the same steps as in Example 10. When more than 95% of the ink on the surface of the waste plastic was removed, the plastic was taken out. The de-inking time was 1.5 hours.

[0137] Tween 80 can emulsify and remove ink particles to prevent redeposition, and can also be compounded with other ingredients to enhance solubility and suspending ability. Without this ingredient, ink is prone to redeposition, requiring repeated deinking, the synergistic effect disappears, deinking efficiency decreases, and deinking time is prolonged.

[0138] Comparative Example 6

[0139] Same as Example 1, except that the plastic deinking agent is composed only of organic solvents, and the composition and ratio of the organic solvents are the same as in Example 1.

[0140] The plastic was de-inked using the above-mentioned plastic de-inking agent, following the same steps as in Example 10. When more than 95% of the ink on the surface of the waste plastic was removed, the plastic was taken out. The de-inking time was 1.5 hours.

[0141] Tween 80 and fatty alcohol polyoxyethylene ether can synergistically emulsify and suspend inks to prevent redeposition, and also enhance the wetting effect on PP surfaces. Without the addition of surfactants, inks are prone to redeposition, requiring repeated deinking, and insufficient wetting of the PP surface greatly reduces deinking efficiency, resulting in prolonged deinking time.

[0142] Comparative Example 7

[0143] Same as Example 1, except that the plastic deinking agent is composed only of surfactants, and the surfactant components and ratios are the same as in Example 1.

[0144] The plastic was de-inked using the above-mentioned plastic de-inking agent, following the same steps as in Example 10. When more than 95% of the ink on the surface of the waste plastic was removed, the plastic was taken out. The de-inking time was 2.5 hours.

[0145] The four organic solvents—DPG, n-butyl acetate, isoflurane, and N-methylpyrrolidone—work synergistically to achieve surface wetting and penetration on PP, stabilize the concentration of the deinking system, and dissolve and peel off polar inks, forming the core of efficient deinking. Without the addition of organic solvents, the system loses its crucial roles in wetting, stabilizing, and dissolving, making it difficult for ink to detach from the PP substrate, resulting in a sharp drop in deinking efficiency and prolonged deinking time.

[0146] Taking the plastic deinking agent provided in Example 1 of this invention as an example, caustic soda flakes were added to adjust the pH to 13, resulting in an alkaline deinking agent solution. The plastic was then immersed in this solution for 2 hours. After immersion, the plastic was transferred to a high-speed friction machine (1000 r / min) and deinked for 1 hour with the alkaline deinking agent solution. The plastic surface was then rinsed with water and finally dried. The deinking effect was observed, and the results are as follows: Figure 1 As shown, adding alkali results in better deinking, indicating that adding caustic soda flakes can shorten the deinking time to some extent.

[0147] It should be noted that the plastic samples used in the deinking experiment were cut from the surface of polypropylene (PP) plastic products (such as plastic milk tea cups) that contained ink.

[0148] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A plastic deinking agent, characterized in that, It consists of organic solvents, surfactants, and water; The organic solvent is composed of ether solvents, ester solvents, ketone solvents and amide solvents; The surfactant is composed of polysorbate surfactants and polyoxyethylene surfactants.

2. The plastic deinking agent according to claim 1, characterized in that, The mass ratio of the organic solvent to the surfactant is (3-7):1; The mass of the water is 5 to 10 times the total mass of the organic solvent and surfactant.

3. The plastic deinking agent according to claim 1, characterized in that, The ether solvent is selected from one of propylene glycol methyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl ether, and dipropylene glycol diethyl ether.

4. The plastic deinking agent according to claim 1, characterized in that, The ester solvent is selected from one of n-butyl acetate, isobutyl acetate, sec-butyl acetate, and tert-butyl acetate.

5. The plastic deinking agent according to claim 1, characterized in that, The ketone solvent is selected from one of acetone, cyclohexanone, isoflurone, methylcyclohexanone, and isopropylidene acetone.

6. The plastic deinking agent according to claim 1, characterized in that, The amide solvent is selected from N-methylpyrrolidone and N-butylpyrrolidone.

7. The plastic deinking agent according to claim 1, characterized in that, The polysorbate surfactant is selected from one of Tween 20, Tween 40, Tween 60 and Tween 80; And / or, the polyoxyethylene surfactant is selected from one of fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, polyol polyoxyethylene ether fatty acid esters, and fatty acid methyl ester ethoxylates.

8. A method for preparing a plastic deinking agent according to any one of claims 1 to 7, characterized in that, The organic solvent and surfactant are mixed, water is added, and the mixture is stirred until completely dissolved to obtain the plastic deinking agent.

9. The application of a plastic deinking agent as described in any one of claims 1 to 7 in plastic deinking.

10. A method for deinking plastic, characterized in that, The plastic is immersed in the plastic deinking agent according to any one of claims 1 to 7, and then stirred, washed and dried.

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