Method for modifying and recycling waste ABS (Acrylonitrile Butadiene Styrene) plastic through electron beam irradiation

Abstract

The invention discloses a method for modifying and recycling waste ABS (Acrylonitrile Butadiene Styrene) plastics through electron beam irradiation, and relates to the technical field of recycling of waste ABS plastics. The recycled waste ABS plastic and the cross-linking agent are subjected to melt blending and extrusion to prepare particles, then the particles are subjected to electron beam irradiation treatment, and the comprehensive performance of the finally obtained regenerated ABS plastic is remarkably improved compared with that of original waste ABS plastic. Meanwhile, the method is simpler in process and less in additive, reduces the cost of modification and regeneration of the waste plastic, has the advantages of low energy consumption, no pollution to the environment and the like, and can be applied to the field of recycling and regeneration of various waste ABS plastics.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of recycling of waste ABS plastics, and particularly relates to a method for modifying and recycling waste ABS plastics by electron beam irradiation. BACKGROUND

[0002] Plastics have excellent electrical insulation, heat insulation and other properties, and are widely used in electrical appliances, accounting for about 10-30% of the weight of electrical appliances. With the continuous acceleration of the upgrading of electronic and electrical products, the amount of waste electrical plastics continues to increase. Acrylonitrile (A)-butadiene (B)-styrene (S) copolymer (ABS) is the most commonly used plastic in electrical appliances, and most of the waste ABS plastics are directly discarded, buried or incinerated. However, the leaching of heavy metals (arsenic, mercury, chromium, cadmium, lead, etc.) and halogen substances (bromine, chlorine, etc.) in ABS causes serious pollution to soil, water, air and other environments, and plastic resources are also greatly wasted. Therefore, recycling of waste ABS plastics can effectively solve the problems of resource waste and environmental pollution.

[0003] During use, ABS plastics are easily oxidized and degraded (i.e., "aged") due to the influence of light, heat and oxygen. The mechanical properties (such as impact performance and tensile strength) of aged ABS plastics are greatly reduced, and the added value of products directly recycled and utilized is low. Therefore, in order to improve the mechanical properties of waste ABS plastics, adding a chemical modifier for treatment is one of the commonly used technologies for modifying and recycling waste ABS plastics.

[0004] For example, patent application CN108912588A discloses a processing method for enhancing and recycling waste ABS plastics. The method mixes waste ABS recycled materials with high glue powder, thermoplastic elastomer, composite filler, microcrystalline wax, colorant and ultraviolet absorber, and granulates them to improve the mechanical properties such as tensile strength, impact strength and bending strength of the recycled plastics. This method uses a large number of additives, and the raw materials for preparing the composite filler are more, the steps are complex, and the cost is high.

[0005] Patent application CN119859375A discloses a recycled ABS modified material and a preparation method thereof. The method melt-blends waste ABS plastics with unsaturated acid anhydride compounds, unsaturated rubber and initiators, and extrudes them into a shape. Although good mechanical properties are obtained, a large amount of raw materials is also used.

[0006] Therefore, there is an urgent need to invent a modification method that has little environmental pollution, does not require additional additives, has a simple process, relatively low cost, and can greatly improve the mechanical properties of waste ABS plastics. SUMMARY

[0007] The present application aims at the deficiency of the existing waste ABS plastic chemical modification recycling technology, and provides a waste ABS plastic recycling method, which uses an electron accelerator to irradiate and modify the waste ABS plastic, so that the molecular weight of the waste ABS plastic is increased, and the mechanical properties are greatly improved.

[0008] The present application provides a waste ABS plastic recycling method, which comprises the following steps:

[0009] The waste ABS plastic is cleaned, dried and crushed to obtain waste ABS plastic powder; and the crosslinking agent is dried.

[0010] The waste ABS plastic powder and the crosslinking agent are melt-blended and extruded and granulated to obtain composite material particles.

[0011] The composite material particles are subjected to electron beam irradiation treatment to obtain regenerated ABS plastic.

[0012] The irradiation dose of the electron beam irradiation treatment is 80-320 kGy, the dose rate is 20 kGy / pass, the accelerator energy is 10 MeV, and the irradiation time is 24-96 min.

[0013] Further, the drying method is 50-70℃ drying for 6-12 h.

[0014] Further, the mass ratio of the waste ABS plastic powder to the crosslinking agent is (40-50):1.

[0015] Further, the crosslinking agent is 2,2'-(1,3-phenylene)-dioxazoline (abbreviated as dioxazoline, 1,3-PBO).

[0016] Further, the extrusion granulation conditions are 190-210℃, and the screw rotation speed is 80-85 rpm.

[0017] Further, the temperature of each section of the double-screw extruder used for the extrusion granulation from the first section to the die head is 190℃, 200℃, 210℃ and 200℃, respectively.

[0018] Further, the composite material particles are cylindrical particles with a diameter of 2-5 mm.

[0019] Further, the irradiation dose of the electron beam irradiation treatment is 240 kGy, and the irradiation time is 72 min.

[0020] The application is to realize the green high-value recycling of waste ABS plastics, through the high-energy electron beam irradiation attack of crosslinking agent by an electron accelerator, the generated active free radicals and the free radicals on the aging ABS plastic molecules have crosslinking reaction, the aging broken molecular chains are effectively connected, the crosslinked network structure is formed, and finally the average molecular weight of the waste ABS plastics is increased, and the mechanical properties are significantly improved.

[0021] Compared with the prior art, the application has the advantages that:

[0022] Compared with the existing waste ABS plastic recycling modification technology, the method of the application has the advantages of simpler operation process, fewer additives, reduced cost of waste plastic modification and regeneration, less energy consumption, no pollution to the environment, etc., and can be applied to the recycling and regeneration field of various waste ABS plastics.

[0023] The experimental results show that after the waste ABS plastics are modified by the method of the application, the tensile strength of the final material is improved, and the highest reaches 28.67 MPa, which is increased by 230%; the impact strength is also improved, and is all higher than 4.5 kJ / m 2 , which is increased by 200 % at the maximum; and the average molecular weight is increased. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The mechanical properties of the waste ABS plastics before and after irradiation. DETAILED DESCRIPTION

[0025] The technical solutions of the application will be described clearly and completely below, obviously, the described embodiments are only part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0026] The method for recycling and utilizing waste ABS plastics provided by the application is suitable for waste ABS plastics from any source. Compared with the original waste ABS plastics, the comprehensive performance of the regenerated ABS plastics treated by the method of the application is significantly enhanced.

[0027] In order to facilitate comparison, the waste ABS plastics used in the following specific embodiments are all from waste ABS plastics of waste electrical appliances, such as waste ABS recycling materials obtained by disassembling waste fan housings and fan blades.

[0028] In some specific embodiments of the application, the method for recycling and utilizing waste ABS plastics comprises the following steps:

[0029] (1) The waste ABS plastic is cleaned, dried, and crushed to obtain waste ABS plastic powder; the crosslinking agent is dried.

[0030] (2) The waste ABS plastic powder and the crosslinking agent are melt-blended and extruded and granulated to obtain composite material particles.

[0031] (3) The composite material particles are subjected to electron beam irradiation treatment to obtain regenerated ABS plastic.

[0032] The irradiation dose of the electron beam irradiation treatment is 80-320 kGy, the dose rate is 20 kGy / pass, the accelerator energy is 10 MeV, and the irradiation time is 24-96 min.

[0033] Optionally, before treatment, the waste ABS plastic needs to be first classified according to color, and then washed with tap water to remove surface-attached dirt and foreign matter.

[0034] Optionally, the drying method is 50-70℃ drying for 6-12 h.

[0035] Optionally, the mass ratio of the waste ABS plastic powder to the crosslinking agent is (40-50):1.

[0036] Specifically, the crosslinking agent is 2,2'-(1,3-phenylene)-dioxazoline (abbreviated as dioxazoline, 1,3-PBO).

[0037] Optionally, the extrusion granulation conditions are 190-210℃, and the screw rotation speed is 80 rpm.

[0038] Optionally, the temperature of each section of the twin-screw extruder used for the extrusion granulation from the first section to the head is 190℃, 200℃, 210℃, and 200℃, respectively.

[0039] Optionally, the composite material particles are cylindrical particles with a diameter of 2-5 mm.

[0040] Specifically, the irradiation dose of the electron beam irradiation treatment is 240 kGy, and the irradiation time is 72 min.

[0041] Example 1

[0042] The method for recycling waste ABS plastic used in this example has the following steps:

[0043] (1) Pretreatment of waste ABS plastic from electrical appliances and crosslinking agent

[0044] The collected waste ABS plastic of electrical appliances is classified according to color, the black plastic is washed with tap water to remove surface attached dirt and foreign matter, and then is placed in a drying machine for drying treatment, the drying machine temperature is set to 70 DEG C, and the drying time is 12 h. The dried waste ABS plastic of electrical appliances is put into a pulverizer for pulverizing treatment, and the pulverized powder is passed through a 10 mesh sieve to obtain waste ABS plastic powder for standby;

[0045] Meanwhile, the crosslinking agent 1,3-dioxolane (1,3-PBO) is placed in a vacuum drying oven and continuously dried at 50 DEG C for 6 h.

[0046] (2) melt blending

[0047] The pretreated waste ABS plastic powder of electrical appliances 1000 g and the crosslinking agent 1,3-dioxolane (1,3-PBO) 25 g are mixed uniformly and put into a double screw extruder for melt blending.

[0048] The temperature of each section of the extruder from the first section to the head is 190 DEG C, 200 DEG C, 210 DEG C, and 200 DEG C, and the screw rotation speed is 80 rpm. The material after melt extrusion is cooled and cut into cylindrical composite particles with a diameter of 2-5 mm by a pelletizer.

[0049] (3) electron beam irradiation

[0050] The composite particles obtained in step (2) are irradiated at room temperature by an electron accelerator (electron accelerator energy 10 MeV, power 20 kW, average beam current 1.94 mA, repetition frequency 621 Hz) to obtain the final regenerated ABS plastic, the irradiation dose is 80 kGy, the dose rate is 20 kGy / pass, and the irradiation time is 24 min.

[0051] In this embodiment, the tensile strength of the final regenerated ABS plastic is 8.72 MPa, and the impact strength is 3.28 kJ / m 2 .

[0052] Example 2

[0053] The method for recycling waste ABS plastic provided in this embodiment is basically the same as that in example 1. The difference lies in that the electron beam irradiation dose is 160 kGy, and the irradiation time is 48 min.

[0054] Example 3

[0055] The method for recycling waste ABS plastic provided in this embodiment is basically the same as that in example 1. The difference lies in that the electron beam irradiation dose is 240 kGy, and the irradiation time is 72 min.

[0056] Example 4

[0057] The method for recycling waste ABS plastic provided by the embodiment is basically the same as that of embodiment 1. The difference lies in that the re-irradiation dose of the electron beam irradiation is 320 kGy, and the irradiation time is 96 min.

[0058] Comparative example 1

[0059] The waste ABS plastic provided by the comparative example is not subjected to irradiation treatment. That is, after the collected waste ABS plastic of electronic appliances is treated according to steps (1) and (2) of embodiment 1, the final ABS plastic particles are obtained.

[0060] Comparative example 2

[0061] The waste ABS plastic provided by the comparative example is not added with any crosslinking agent, but is directly subjected to electron beam irradiation treatment. The specific steps are as follows:

[0062] (1) Pretreatment of waste ABS plastic of electronic appliances: the pretreatment method of the waste ABS plastic of electronic appliances is the same as that of step (1) of embodiments 1 and 3.

[0063] (2) Electron beam irradiation: 1000 g of the waste ABS plastic powder obtained in step (1) is subjected to irradiation at room temperature by using the same electron accelerator as that of embodiments 1 and 3; the irradiation dose is 240 kGy, the dose rate is 20 kGy / pass, and the irradiation time is 72 min, that is, the irradiation mode is the same as that of embodiment 3. After the irradiation is completed, the final recycled ABS plastic is obtained.

[0064] Comparative example 3

[0065] The method for recycling waste ABS plastic provided by the comparative example is basically the same as that of embodiment 1. The difference lies in that the irradiation dose of the electron beam irradiation is 400 kGy, and the irradiation time is 120 min.

[0066] Test example: performance test of recycled ABS plastic

[0067] The tensile strength, impact strength and average molecular weight of the recycled ABS plastics prepared in Examples 1-4 and Comparative Examples 1-3 and the recycled original waste ABS plastics of electronic appliances were tested. The tensile strength was tested according to the standard test method GB / T 1040-2006. The impact strength was tested according to the standard test method GB / T 1843-2008. The average molecular weight was tested by gel permeation chromatography. The test method was as follows: a series of polystyrene standards with different molecular weights were dissolved in chromatographic grade tetrahydrofuran, and gel permeation chromatography was performed to draw a standard working curve. Then, the recycled ABS materials prepared in each example and comparative example were dissolved in chromatographic grade tetrahydrofuran, and the weight average molecular weight (Mw) of the materials was calculated according to the established standard curve. The test results are shown in Table 1.

[0068] Table 1 Performance test results of recycled ABS plastics of examples and comparative examples

[0069]

[0070] From Figure 1 As can be seen from Table 1, after adding a crosslinking agent to the waste ABS recyclates, melt blending, and then electron beam irradiation, the tensile strength and impact strength of the material can be improved, and the mechanical properties of the recycled plastics are obviously improved. The tensile strength and impact strength of the recycled ABS plastics of Examples 1-4 are significantly improved, and the weight average molecular weight is increased compared to the original waste ABS recyclates of electronic appliances. The comprehensive mechanical properties of Examples 1-4 are better than those of Comparative Examples 1-3. With the increase of the irradiation dose, the tensile strength first increases and then decreases. When the irradiation dose is 240 kGy (i.e. Example 3), the tensile strength reaches the best, which is 28.67 MPa; at the same time, the weight average molecular weight also reaches the maximum, and the impact strength is 8.01 kJ / m 2 2. The comprehensive mechanical properties of Example 3 are the best.

[0071] The above specific embodiments describe the implementation of the present application in detail, but the present application is not limited to the specific details in the above embodiments. Within the scope of the claims and technical concepts of the present application, the technical solutions of the present application can be modified and changed in many simple ways, and these simple modifications all belong to the protection scope of the present application.

Claims

1. A method for recycling waste ABS plastics, characterized in that: The following steps are involved: The waste ABS plastic is cleaned, dried and crushed to obtain waste ABS plastic powder; the cross-linking agent is dried; The waste ABS plastic powder and the cross-linking agent are melt-blended and extruded into granules to obtain composite material granules; subjecting the composite material particles to electron beam irradiation to obtain recycled ABS plastic; The electron beam irradiation treatment has an irradiation dose of 80-320 kGy, a dose rate of 20 kGy / pass, an accelerator energy of 10 MeV, and an irradiation time of 24-96 min.

2. The method for recycling waste ABS plastics according to claim 1, characterized in that: The drying method is to dry at 50-70° C. for 6-12 hours.

3. The method for recycling waste ABS plastic according to claim 1, characterized in that: The mass ratio of the waste ABS plastic powder to the cross-linking agent is (40-50):

1.

4. The method for recycling waste ABS plastics according to claim 3, characterized in that: The mass ratio of the waste ABS plastic powder to the cross-linking agent is 40:

1.

5. The method for recycling waste ABS plastics according to claim 1, characterized in that: The cross-linking agent is 2,2'-(1,3-phenylene)-dioxazoline.

6. The method for recycling waste ABS plastics according to claim 1, characterized in that: The conditions for extrusion granulation are 190-210°C and a screw speed of 80-85 rpm.

7. The method for recycling waste ABS plastics according to claim 1, characterized in that: The temperatures of the twin-screw extruder from one section to the die head for the extrusion granulation are 190° C., 200° C., 210° C., and 200° C., respectively.

8. The method for recycling waste ABS plastics according to claim 1, characterized in that: The composite material particles are cylindrical particles with a diameter of 2-5 mm.

9. The method for recycling waste ABS plastics according to claim 1, characterized in that: The electron beam irradiation treatment has an irradiation dose of 240 kGy and an irradiation time of 72 min.

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