Waste plastic regeneration process

Abstract

The invention discloses a waste plastic regeneration process. The waste plastic regeneration process comprises the following steps: 1) crushing treatment: crushing waste plastic into plastic particles; (2) cleaning treatment is conducted, specifically, the plastic particles are preliminarily cleaned with clear water, stirring is kept in the cleaning process, the sinking plastic particles are collected after cleaning is completed, and the sinking plastic particles are further cleaned with a composite cleaning agent; 3) bleaching treatment: washing the cleaned plastic particles with clear water, and then putting the washed plastic particles into a bleaching pool for bleaching treatment, wherein ultrasonic assistance is adopted in the bleaching treatment process; and 4) air-drying the bleached plastic particles, soaking the plastic particles in plant vinegar, adding a proper amount of nano microcrystalline cellulose into the air-dried plastic particles, uniformly stirring, and granulating. The prepared plastic particle product is not prone to yellowing and stable in color, and the mechanical property is well improved.

Description

Technical Field

[0001] The invention relates to the technical field of waste plastic treatment, and in particular to a waste plastic recycling process. Background Art

[0002] Waste plastic granulation is to classify the collected waste plastics, and then convert them into usable plastic particles through processing and treatment, so as to realize the reuse of waste plastics. In the prior art, the process of recycling and processing waste plastics usually includes collection and classification, cleaning and crushing, melting and extrusion granulation. However, the plastic particles obtained by this simple process have uneven color and obvious yellowing. Researchers have conducted a lot of research and development on this. For example, the Chinese patent with announcement number CN110103435A discloses a production process of arc-shaped plastic profiles, which includes dissolving the thermoplastic plastic pellets through a thermoplastic plastic extruder, extruding through a special mold, extruding the cross-section-shaped thermoplastic plastic material into a cooling pool, and cutting the thermoplastic plastic fender with an electric saw after extrusion to produce the curvature of the fender. The extrusion process reduces the time that the thermoplastic plastic material is in the mold to avoid yellowing of the material. The Chinese patent with the announcement number CN115890971A discloses a waste PP recycled plastic that can be used for spunbond nonwoven fabrics. The recycling process mainly includes crushing, cleaning, air separation, color sorting, melt granulation and other steps. The obtained recycled plastic particles have simple resin composition, low yellowing degree, and certain toughness. Most of the above technical studies have alleviated the yellowing phenomenon of recycled plastic particles or products through process improvements. However, in actual applications, due to the wide sources of waste plastics, the yellowing phenomenon of the final plastic product can only be alleviated by adjusting the process. Therefore, the present invention aims to provide a waste plastic recycling process to better meet the actual production needs. Summary of the invention

[0003] The technical problem solved by the present invention is to provide a waste plastic recycling process to solve the problems in the above-mentioned background technology.

[0004] The technical problem solved by the present invention is achieved by adopting the following technical solutions:

[0005] A waste plastic recycling process comprises the following steps:

[0006] 1) Crushing: crushing waste plastics into plastic particles;

[0007] 2) Cleaning: The plastic particles are preliminarily cleaned with clean water, and stirring is maintained during the cleaning process. After the cleaning is completed, the sunken plastic particles are collected and further cleaned with a composite cleaning agent;

[0008] 3) Bleaching treatment: After the cleaning, the plastic particles are rinsed with clean water and placed in a bleaching tank for bleaching treatment, and ultrasound is used to assist the bleaching process;

[0009] 4) After the bleached plastic particles are air-dried, they are soaked in plant vinegar solution, and after air-drying, a proper amount of nano-microcrystalline cellulose is added to the plastic particles, and the mixture is stirred evenly and granulated.

[0010] Furthermore, the particle size of the plastic particles after crushing is 0.5 to 1.5 cm.

[0011] Furthermore, in the cleaning step, the composite cleaning agent includes the following raw materials in parts by weight: 5-10 parts of phosphate, 5-10 parts of betaine, 10-15 parts of sodium carbonate, 7-8 parts of octadecyl polyoxyethylene ether, and 2-8 parts of isopropyl alcohol.

[0012] Furthermore, in the cleaning step, the composite cleaning agent includes the following raw materials in parts by weight: 8 parts of phosphate, 10 parts of betaine, 12 parts of sodium carbonate, 8 parts of octadecyl polyoxyethylene ether, and 4 parts of isopropyl alcohol.

[0013] Furthermore, in the bleaching step, the bleaching liquid is a hydrogen peroxide solution with a mass concentration of 10 to 12%, and the bleaching time is 2 to 4 hours.

[0014] Furthermore, in the bleaching step, the ultrasonic power is 40 to 50 W / L.

[0015] Furthermore, the plant vinegar is bamboo vinegar or wood vinegar.

[0016] Furthermore, the plant vinegar is a plant vinegar solution with a mass concentration of 30-40%, the amount of the plant vinegar solution added is based on the amount of the plastic particles being submerged, and the soaking time is 5-10 minutes.

[0017] Furthermore, the added amount of the nano-microcrystalline cellulose accounts for 0.5-1% of the plastic particles. ,

[0018] Beneficial effects: The waste plastic recycling process of the present invention can fully remove impurities on the surface of plastic particles through preliminary impurity removal by washing and further washing with a composite cleaning agent, further fade the color of the plastic particles themselves through bleaching treatment, and further play a good antioxidant and better light stability in the subsequent melt granulation process through subsequent plant vinegar soaking and the addition of nano-microcrystalline cellulose, thereby well preventing the yellowing of plastic raw material particles. The present invention combines various processes to make the prepared plastic particle products not easy to yellow, stable in color and well improved in mechanical properties.

[0019] In the waste plastic recycling process described in the present invention, during the cleaning process, clean water is used for preliminary cleaning to preliminarily clean and separate impurities attached to the surface of plastic particles, and the composite cleaning agent used is a combination of penetrant, surfactant, oxidant, dispersant and polar solvent, so that the stubborn stains on the surface of plastic particles are fully removed, thereby avoiding the retention of impurities and the occurrence of yellowing in subsequent processing, thereby better ensuring the quality stability of the final plastic particle product. DETAILED DESCRIPTION

[0020] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments.

[0021] Example 1

[0022] The waste plastic recycling process described in this embodiment includes the following steps:

[0023] 1) Crushing: The collected waste plastics are split and the same type of waste plastics are crushed into plastic particles in a crusher. The particle size of the crushed plastic particles is 0.5 to 1.5 cm.

[0024] 2) Cleaning: The plastic particles are preliminarily cleaned with clean water, and stirring is maintained during the cleaning process. The cleaning can be performed multiple times according to the actual situation until the cleaning liquid is clear;

[0025] After cleaning, the plastic particles that sink are collected and further cleaned with a composite cleaning solution; the concentration of the composite cleaning agent in the composite cleaning solution is about 2%; the composite cleaning agent can be recycled. The composite cleaning agent includes the following raw materials in parts by weight: 8 parts of phosphate, 10 parts of betaine, 12 parts of sodium carbonate, 8 parts of octadecyl polyoxyethylene ether, and 4 parts of isopropyl alcohol.

[0026] 3) Bleaching treatment: The cleaned plastic particles are rinsed with clean water and then placed in a bleaching tank for bleaching. The bleaching liquid used in the bleaching treatment is a hydrogen peroxide solution with a mass concentration of 12%. The bleaching time is 3 hours. Ultrasonic assistance is used during the bleaching process; the ultrasonic power is 45W / L.

[0027] 4) air-drying the bleached plastic particles, and then soaking them in plant vinegar, wherein the plant vinegar is wood vinegar with a mass concentration of 35%, and the wood vinegar is a commercially available product; the amount of plant vinegar solution added is based on the amount of the plastic particles being submerged, and the soaking time is 8 minutes, so that the wood vinegar is evenly distributed on the surface of the plastic particles;

[0028] After air drying, add 0.8% of nano-microcrystalline cellulose to the plastic particles, stir evenly and granulate.

[0029] Example 2

[0030] The waste plastic recycling process described in this embodiment includes the following steps:

[0031] 1) Crushing: The collected waste plastics are split and the same type of waste plastics are crushed into plastic particles in a crusher. The particle size of the crushed plastic particles is 0.5 to 1.5 cm.

[0032] 2) Cleaning: The plastic particles are preliminarily cleaned with clean water, and stirring is maintained during the cleaning process. The cleaning can be performed multiple times according to the actual situation until the cleaning liquid is clear;

[0033] After cleaning, the plastic particles that sink are collected and further cleaned with a composite cleaning solution; the concentration of the composite cleaning agent in the composite cleaning solution is about 2%; the composite cleaning agent can be recycled. The composite cleaning agent includes the following raw materials in parts by weight: 10 parts of phosphate, 5 parts of betaine, 12 parts of sodium carbonate, 7 parts of octadecyl polyoxyethylene ether, and 8 parts of isopropyl alcohol.

[0034] 3) Bleaching treatment: The cleaned plastic particles are rinsed with clean water and then placed in a bleaching tank for bleaching. The bleaching liquid used in the bleaching treatment is a hydrogen peroxide solution with a mass concentration of 10%. The bleaching time is 4 hours. Ultrasonic assistance is used during the bleaching process; the ultrasonic power is 40W / L.

[0035] 4) air-drying the bleached plastic particles, and then soaking them in plant vinegar, wherein the plant vinegar is wood vinegar with a mass concentration of 30%, and the wood vinegar is a commercially available product; the amount of plant vinegar solution added is based on the amount of the plastic particles being submerged, and the soaking time is 10 minutes, so that the wood vinegar is evenly distributed on the surface of the plastic particles;

[0036] After air drying, add 1.0% of nano-microcrystalline cellulose to the plastic particles, stir evenly and granulate.

[0037] Comparative Example 1

[0038] In this comparative example, the waste plastic recycling process comprises the following steps:

[0039] 1) Crushing: The collected waste plastics are split and the same type of waste plastics are crushed into plastic particles in a crusher. The particle size of the crushed plastic particles is 0.5 to 1.5 cm.

[0040] 2) Cleaning: The plastic particles are preliminarily cleaned with clean water, and stirring is maintained during the cleaning process. The cleaning can be performed multiple times according to the actual situation until the cleaning liquid is clear;

[0041] After cleaning, the sank plastic particles are collected and further cleaned with a sodium hydroxide solution having a mass concentration of 20%.

[0042] 3) Bleaching treatment: The cleaned plastic particles are rinsed with clean water and then placed in a bleaching tank for bleaching. The bleaching liquid used in the bleaching treatment is a hydrogen peroxide solution with a mass concentration of 10%. The bleaching time is 4 hours. Ultrasonic assistance is used during the bleaching process; the ultrasonic power is 40W / L.

[0043] 4) air-drying the bleached plastic particles, and then soaking them in plant vinegar, wherein the plant vinegar is wood vinegar with a mass concentration of 30%, and the wood vinegar is a commercially available product; the amount of plant vinegar solution added is based on the amount of the plastic particles being submerged, and the soaking time is 10 minutes, so that the wood vinegar is evenly distributed on the surface of the plastic particles;

[0044] After air drying, add 1.0% of nano-microcrystalline cellulose to the plastic particles, stir evenly and granulate.

[0045] Comparative Example 2

[0046] The waste plastic recycling process comprises the following steps:

[0047] 1) Crushing: The collected waste plastics are split and the same type of waste plastics are crushed into plastic particles in a crusher. The particle size of the crushed plastic particles is 0.5 to 1.5 cm.

[0048] 2) Cleaning: The plastic particles are preliminarily cleaned with clean water, and stirring is maintained during the cleaning process. The cleaning can be performed multiple times according to the actual situation until the cleaning liquid is clear;

[0049] After cleaning, the plastic particles that sink are collected and further cleaned with a composite cleaning solution; the concentration of the composite cleaning agent in the composite cleaning solution is about 2%; the composite cleaning agent can be recycled. The composite cleaning agent includes the following raw materials in parts by weight: 20 parts of phosphate, 3 parts of betaine, 5 parts of sodium carbonate, 2 parts of octadecyl polyoxyethylene ether, and 10 parts of isopropyl alcohol.

[0050] 3) Bleaching treatment: The cleaned plastic particles are rinsed with clean water and then placed in a bleaching tank for bleaching. The bleaching liquid used in the bleaching treatment is a hydrogen peroxide solution with a mass concentration of 10%. The bleaching time is 4 hours. Ultrasonic assistance is used during the bleaching process; the ultrasonic power is 40W / L.

[0051] 4) air-drying the bleached plastic particles, and then soaking them in plant vinegar, wherein the plant vinegar is wood vinegar with a mass concentration of 30%, and the wood vinegar is a commercially available product; the amount of plant vinegar solution added is based on the amount of the plastic particles being submerged, and the soaking time is 10 minutes, so that the wood vinegar is evenly distributed on the surface of the plastic particles;

[0052] After air drying, add 1.0% of nano-microcrystalline cellulose to the plastic particles, stir evenly and granulate.

[0053] Comparative Example 3

[0054] The waste plastic recycling process comprises the following steps:

[0055] 1) Crushing: The collected waste plastics are split and the same type of waste plastics are crushed into plastic particles in a crusher. The particle size of the crushed plastic particles is 0.5 to 1.5 cm.

[0056] 2) Cleaning: The plastic particles are preliminarily cleaned with clean water, and stirring is maintained during the cleaning process. The cleaning can be performed multiple times according to the actual situation until the cleaning liquid is clear;

[0057] After cleaning, the plastic particles that sink are collected and further cleaned with a composite cleaning solution; the concentration of the composite cleaning agent in the composite cleaning solution is about 2%; the composite cleaning agent can be recycled. The composite cleaning agent includes the following raw materials in parts by weight: 10 parts of phosphate, 5 parts of betaine, 12 parts of sodium carbonate, 7 parts of octadecyl polyoxyethylene ether, and 8 parts of isopropyl alcohol.

[0058] 3) After the cleaned plastic particles are air-dried, they are soaked in plant vinegar solution, wherein the plant vinegar is wood vinegar with a mass concentration of 30%, and the wood vinegar is a commercially available product; the amount of the plant vinegar solution added is based on the amount of the plastic particles being submerged, and the soaking time is 10 minutes, so that the wood vinegar is evenly distributed on the surface of the plastic particles;

[0059] After air drying, add 1.0% of nano-microcrystalline cellulose to the plastic particles, stir evenly and granulate.

[0060] Comparative Example 4

[0061] The waste plastic recycling process comprises the following steps:

[0062] 1) Crushing: The collected waste plastics are split and the same type of waste plastics are crushed into plastic particles in a crusher. The particle size of the crushed plastic particles is 0.5 to 1.5 cm.

[0063] 2) Cleaning: The plastic particles are preliminarily cleaned with clean water, and stirring is maintained during the cleaning process. The cleaning can be performed multiple times according to the actual situation until the cleaning liquid is clear;

[0064] After cleaning, the plastic particles that sink are collected and further cleaned with a composite cleaning solution; the concentration of the composite cleaning agent in the composite cleaning solution is about 2%; the composite cleaning agent can be recycled. The composite cleaning agent includes the following raw materials in parts by weight: 10 parts of phosphate, 5 parts of betaine, 12 parts of sodium carbonate, 7 parts of octadecyl polyoxyethylene ether, and 8 parts of isopropyl alcohol.

[0065] 3) Bleaching treatment: The cleaned plastic particles are rinsed with clean water and then placed in a bleaching tank for bleaching. The bleaching liquid used in the bleaching treatment is a hydrogen peroxide solution with a mass concentration of 10%. The bleaching time is 4 hours. Ultrasonic assistance is used during the bleaching process; the ultrasonic power is 40W / L.

[0066] 4) After the bleached plastic particles are air-dried, 1.0% of nano-microcrystalline cellulose is added to the plastic particles, and the mixture is stirred evenly and granulated.

[0067] Comparative Example 5

[0068] The waste plastic recycling process comprises the following steps:

[0069] 1) Crushing: The collected waste plastics are split and the same type of waste plastics are crushed into plastic particles in a crusher. The particle size of the crushed plastic particles is 0.5 to 1.5 cm.

[0070] 2) Cleaning: The plastic particles are preliminarily cleaned with clean water, and stirring is maintained during the cleaning process. The cleaning can be performed multiple times according to the actual situation until the cleaning liquid is clear;

[0071] After cleaning, the plastic particles that sink are collected and further cleaned with a composite cleaning solution; the concentration of the composite cleaning agent in the composite cleaning solution is about 2%; the composite cleaning agent can be recycled. The composite cleaning agent includes the following raw materials in parts by weight: 10 parts of phosphate, 5 parts of betaine, 12 parts of sodium carbonate, 7 parts of octadecyl polyoxyethylene ether, and 8 parts of isopropyl alcohol.

[0072] 3) Bleaching treatment: The cleaned plastic particles are rinsed with clean water and then placed in a bleaching tank for bleaching. The bleaching liquid used in the bleaching treatment is a hydrogen peroxide solution with a mass concentration of 10%. The bleaching time is 4 hours. Ultrasonic assistance is used during the bleaching process; the ultrasonic power is 40W / L.

[0073] 4) After the bleached plastic particles are air-dried, they are soaked in plant vinegar solution, wherein the plant vinegar is wood vinegar with a mass concentration of 30%, and the wood vinegar is a commercially available product; the amount of plant vinegar solution added is based on the amount of the plastic particles being submerged, and the soaking time is 10 minutes. During the soaking process, 2.0% of nano-microcrystalline cellulose is added to the plastic particles, and after air-drying, the mixture is stirred evenly and then granulated.

[0074] The plastic particles can be granulated.

[0075] The plastic particles prepared in Examples 1 to 2 and Comparative Examples 1 to 5 were subjected to colorimetric testing, and the granulated particles were used to prepare the same injection molded parts, and the injection molded parts were subjected to strength testing. The results are shown in Table 1.

[0076] Table 1

[0077]

[0078] As shown in Table 1, the waste plastic recycling process of the present invention solves the problem that plastic particles are prone to yellowing and are prone to large color changes during storage by combining crushing, cleaning, bleaching and melt granulation. In addition, the strength of the injection molded parts prepared using the plastic particles of the present invention is significantly improved. As shown in Comparative Examples 1 to 5, when the composite cleaning agent is not used or the composite cleaning agent is improperly configured during the cleaning process, or there is a lack of a bleaching process, or the auxiliary agent is improperly added during the melt granulation process, the color of the final granulated plastic particle product has a key impact. In addition, as shown in Comparative Example 5, when nano-microcrystalline cellulose is not added or improperly added during the melt granulation process, the obtained plastic particles have poor whiteness performance, and the color of the prepared injection molded product is poor, and the strength is significantly reduced.

[0079] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A waste plastic recycling process, characterized in that: The steps include: 1) Crushing: crushing waste plastics into plastic particles; 2) Cleaning: The plastic particles are preliminarily cleaned with clean water, and stirring is maintained during the cleaning process. After the cleaning is completed, the sunken plastic particles are collected and further cleaned with a composite cleaning agent; 3) Bleaching treatment: After the cleaning, the plastic particles are rinsed with clean water and placed in a bleaching tank for bleaching treatment, and ultrasound is used to assist the bleaching process; 4) After the bleached plastic particles are air-dried, they are soaked in plant vinegar solution, and after air-drying, a proper amount of nano-microcrystalline cellulose is added to the plastic particles, and the mixture is stirred evenly and granulated.

2. The waste plastic recycling process according to claim 1, characterized in that: In the crushing step, the particle size of the plastic particles after crushing is 0.5 to 1.5 cm.

3. The waste plastic recycling process according to claim 1, characterized in that: In the cleaning step, the composite cleaning agent comprises the following raw materials in parts by weight: 5-10 parts of phosphate, 5-10 parts of betaine, 10-15 parts of sodium carbonate, 7-8 parts of octadecyl polyoxyethylene ether, and 2-8 parts of isopropanol.

4. The waste plastic recycling process according to claim 3, characterized in that: In the cleaning step, the composite cleaning agent includes the following raw materials in parts by weight: 8 parts of phosphate, 10 parts of betaine, 12 parts of sodium carbonate, 8 parts of octadecyl polyoxyethylene ether, and 4 parts of isopropyl alcohol.

5. The waste plastic recycling process according to claim 1, characterized in that: In the bleaching step, the bleaching liquid is a hydrogen peroxide solution with a mass concentration of 10 to 12%, and the bleaching time is 2 to 4 hours.

6. The waste plastic recycling process according to claim 1, characterized in that: In the bleaching step, the ultrasonic power is 40 to 50 W / L.

7. The waste plastic recycling process according to claim 1, characterized in that: The plant vinegar is bamboo vinegar or wood vinegar.

8. The waste plastic recycling process according to claim 7, characterized in that: The plant vinegar is a plant vinegar solution with a mass concentration of 30-40%. The amount of the plant vinegar solution added is based on the amount of the plastic particles being submerged, and the soaking time is 5-10 minutes.

9. The waste plastic recycling process according to claim 1, characterized in that: The added amount of the nano-microcrystalline cellulose accounts for 0.5-1% of the plastic particles.

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