A waste PET composite material and its preparation equipment and method

Abstract

The present invention relates to a waste PET composite material and a preparation device and method thereof, belonging to the technical field of polymer materials. The preparation device provided by the present invention is an extruder, including a barrel and a screw in the barrel, and the barrel body of the barrel is provided with a main feed port, a first exhaust system, a second exhaust system, a side feed port and a third exhaust system in sequence from the first port; starting from the first port of the barrel, the total length of the barrel is L, the connection position of the first exhaust system is 0.25L-0.33L, the connection position of the second exhaust system is 0.42L-0.5L, the connection position of the side feed port is 0.58L-0.75L, and the connection position of the third exhaust system is 0.83L-0.92L. The waste PET composite material prepared by the scheme of the present invention has high molecular weight, good heat resistance, normal appearance of injection molded parts, and high application value in the recycling and reuse of waste PET.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a waste PET composite material and a preparation device and method thereof. Background Art

[0002] PET bottles have the advantages of light weight, good transparency and high strength, and have been widely used in the field of product packaging. The large amount of discarded PET bottles generated every year is an important source of white pollution, which seriously threatens the ecological environment and human health and causes waste of resources. How to recycle discarded PET bottles has become a focus of attention. During the use and recycling of PET bottles, the performance may deteriorate under the influence of light, oxygen, heat, mechanical and chemical factors, such as reduced mechanical properties and reduced heat resistance; and the molecular weight of PET bottle flakes will also drop significantly during the melt processing, resulting in a significant reduction in material performance.

[0003] When PET bottle flakes are used as raw materials, glass fibers are added, and PET modified engineering plastics are prepared by twin-screw extrusion for recycling, the existing solutions focus more on formula design and less on the impact of processing methods. China Invention Patent Application Publication No. CN103146159A discloses a waste PET heat-resistant viscosity-enhanced composite material and its preparation process, which mainly solves the problem of uneven mixing of waste PET and additives, but does not explore the treatment of byproducts of chain extension reactions and the specific location of glass fiber addition.

[0004] Due to the deterioration of the performance of PET bottle flakes and the poor performance of the obtained materials, the molecular weight of PET is generally increased and the material performance is improved through chain extension reaction. During the twin-screw extrusion process, the by-products produced by the chain extension reaction need to be discharged from the molten material in time to make the chain extension reaction proceed in the positive direction and achieve a better chain extension effect. If the by-products cannot be discharged in time, on the one hand, the by-products will hinder the chain extension reaction and the chain extension effect will be poor; on the other hand, the water produced by the chain extension reaction in the molten material will cause the hydrolysis of PET, reduce the molecular weight of PET and reduce the performance of the material. In addition, the selection of the addition position of glass fiber is also very important: if the addition position is not appropriate, the glass fiber may be over-shredded, the retention length in the plastic matrix is ​​too low, and the performance-enhancing effect is lost; it may also not be fully dispersed, resulting in poor product performance and product appearance defects, such as surface floating fibers; in addition, it will also affect the discharge efficiency of the by-products of the chain extension reaction.

[0005] Therefore, we continue to optimize and develop a waste PET recycling preparation strategy that can effectively discharge by-products and add glass fiber at appropriate locations, so as to further improve the recycling efficiency of waste PET bottles and enhance product performance. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a waste PET composite material and a preparation device and method thereof. The preparation device and method provided by the present invention can effectively discharge the byproducts of the chain extension reaction and feed glass fiber at a suitable position. The prepared PET composite material has a higher molecular weight and good heat resistance, and has a higher practical value.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] In a first aspect, the present invention provides a preparation device for a waste PET composite material, wherein the preparation device for a waste PET composite material is an extruder, comprising a barrel and a screw disposed in the barrel, wherein the barrel comprises a first port and a second port;

[0009] The barrel body of the barrel is provided with a main feeding port, a first exhaust system, a second exhaust system, a side feeding port and a third exhaust system in sequence from the first port; the total length of the barrel is L, and the distance between the connection between the first exhaust system and the barrel and the first port is 0.25L-0.33L; the distance between the connection between the second exhaust system and the barrel and the first port is 0.42L-0.5L; the distance between the connection between the side feeding port and the barrel and the first port is 0.58L-0.75L; the distance between the connection between the third exhaust system and the barrel and the first port is 0.83L-0.92L.

[0010] For the waste PET composite material process prepared by adding glass fiber modification using waste PET as raw material, whether the byproducts of the chain extension reaction can be efficiently discharged during extrusion production and whether the glass fiber is added at an appropriate position are crucial to the product performance. The present invention mainly achieves efficient discharge of the byproducts of the chain extension reaction and good dispersion of the glass fiber by arranging three exhaust systems at a specific distance from the first port on the barrel of the extruder equipment and arranging a side feeding port at an appropriate position for adding glass fiber, thereby achieving the production of a waste PET composite material with better performance.

[0011] The equipment provided by the present invention mainly includes a feeding device consisting of a main feeding port and a side feeding port, an extrusion device consisting of a barrel and a screw, and an exhaust device consisting of an exhaust system. The total length L of the barrel is the length from the first port of the barrel (i.e., the starting end of the barrel) to the second port of the barrel (i.e., the end of the barrel), and the position range of the exhaust system and the side feeding port is calculated by the length of the position where it is installed and connected on the barrel from the first port and the proportional relationship with the total length L of the barrel. The present invention does not specifically limit the position of the main feeding port, but it should be noted that the barrel of the extruder generally has a multi-section barrel body according to different brands and models, and the main feeding port is generally fixed by default on the first section of the barrel body, adjacent to the starting end (first port) of the barrel.

[0012] Selection of the position range of the first exhaust system: After the material enters the barrel, extrusion production begins. The position of 0-0.25L from the first port is mainly the melting and plasticizing section, which completes the transportation, compression, melting and plasticizing of solid raw materials and the initial chain extension reaction. At this stage, on the one hand, the material is in the process of transformation from solid to melt, and the solid material has no sealing effect on the space inside the extruder barrel, and the inside of the barrel is connected to the atmosphere through the feed port of the first section of the extruder barrel, making it difficult to achieve the corresponding conditions for efficient exhaust; on the other hand, the barrel length range space is limited at this stage, and there is not enough space to configure the exhaust system when the normal melting and plasticizing of the material is completed. Therefore, after the material is fully melted and plasticized and the initial chain extension reaction is completed, the exhaust system is configured at the adjacent position downstream to discharge the by-products of the chain extension reaction in time: the first exhaust system is arranged in the position range of 0.25L-0.33L, which can realize the timely discharge of the by-products produced by the initial chain extension reaction at the first time, and promote the chain extension reaction in the positive direction.

[0013] Selection of the position range of the second exhaust system: Since two exhaust systems arranged closely together are easily connected, the second exhaust system cannot be arranged closely together with the first exhaust system, and the two exhaust systems arranged closely together have little significance for improving the discharge effect of the by-products of the chain extension reaction; the second exhaust system cannot be too far away from the first exhaust system to avoid insufficient space downstream to configure the third exhaust system and the side feed port. After the by-products of the chain extension reaction are discharged through the first exhaust system, the chain extension reaction continues within the position range of 0.33L-0.42L. The second exhaust system is configured within the position range of 0.42L-0.5L to discharge the by-products produced during the chain extension reaction, which has a better effect.

[0014] Selection of side feed port position range: The side feed port is used to feed glass fiber, mainly considering the following aspects: a) The glass fiber cannot be sheared too much. If the glass fiber is sheared too much by the extruder screw, the material performance will be greatly reduced, and the meaning of adding glass fiber will be lost. Therefore, the side feed port position is best to ensure that the glass fiber is well sheared and dispersed, and experience a shorter screw shearing process to avoid the glass fiber being sheared too much by the screw. b) Good dispersion of glass fiber. After the glass fiber is fed into the extruder from the side feed port, it needs to go through a certain length of shear dispersion to obtain better material properties. c) The side feed port cannot be arranged close to the exhaust system, because the side feed port is connected to the atmosphere. If the side feed port is close to the exhaust system, it is easy to cause the system to be connected to the atmosphere through the side feed port, affecting the exhaust effect. In summary, the side feed port is arranged in the 0.58L-0.75L position range. On the one hand, it ensures that the glass fiber does not experience excessive shearing, and on the other hand, it ensures the necessary shear dispersion of the glass fiber, and at the same time it is not close to the exhaust system. After the glass fibers are fed into the extruder from the side feed port, they continue to be dispersed through the extruder before reaching the third exhaust system location.

[0015] Selection of the position range of the third exhaust system: The third exhaust system is the last exhaust before the melt reaches the second port of the barrel and the extruder die. On the one hand, it plays a role in exhausting the by-products of the chain extension reaction. On the other hand, after the small molecules are extracted, the melt needs to be immediately extruded and pelletized. Therefore, the third exhaust system is arranged at the position of the extruder head close to the second port of the barrel. The third exhaust system is arranged in the position range of 0.83L-0.92L. After exhausting, the melt is extruded at the die.

[0016] The exhaust systems at the three specific locations mentioned above are indispensable. If only any two of the exhaust systems are arranged, it will lead to unfavorable production conditions, broken bars in the extruded product, poor chain extension effect and low molecular weight of the obtained product. The selection of the position of the side feed port has a significant impact on the heat resistance of the product. If it is set too far forward and too close to the first port, it may cause the thermal deformation temperature of the product to drop significantly and break bars during production; if it is set too far back and too close to the second port, it may cause obvious floating fibers on the appearance of the product injection molded parts and serious break bars during production.

[0017] The preparation equipment of the waste PET composite material provided by the present invention is used for recycling waste PET and producing waste PET composite materials, which can ensure stable production without broken strips and normal appearance of the injection molded parts of the products. The heat deformation temperature of the prepared waste PET composite material can reach above 237°C and the intrinsic viscosity is above 0.94dL / g. It has high molecular weight, good chain extension effect and good product performance. It has high application value in the preparation of modified PET plastics and the recycling and reuse of waste PET.

[0018] Further preferably, the distance between the connection between the first exhaust system and the barrel and the first port is 0.27L; the distance between the connection between the second exhaust system and the barrel and the first port is 0.44L; the distance between the connection between the side feeding port and the barrel and the first port is 0.63L; the distance between the connection between the third exhaust system and the barrel and the first port is 0.86L.

[0019] By adopting the installation and setting strategy of this equipment, better by-product discharge effect and glass fiber reinforcement effect can be achieved in the preparation process, and the waste PET composite material obtained has the highest characteristic viscosity and the best heat resistance.

[0020] Preferably, the screw is configured as meshing parallel co-rotating twin screws.

[0021] Preferably, the aspect ratio of the screw is (47-49): 1. Here, the aspect ratio of the extruder screw refers to the ratio of the effective working length of the screw to the screw diameter. The scheme of the present invention does not limit the specific specifications of the extruder, and it is preferably within the above-mentioned screw aspect ratio range.

[0022] Preferably, the exhaust system is a vacuum exhaust system.

[0023] Preferably, the vacuum degree of the vacuum exhaust system is -0.1-(-0.06) MPa.

[0024] In a second aspect, the present invention provides a method for preparing a waste PET composite material using the above-mentioned waste PET composite material preparation device, comprising the following steps:

[0025] The waste PET, chain extender, nucleating agent, lubricant and antioxidant are mixed and fed into the main feeding port, and the glass fiber is fed into the side feeding port. After heating and extrusion, the waste PET composite material is obtained by drawing, cooling and pelletizing.

[0026] Preferably, the waste PET is PET polyester bottle fragments.

[0027] Preferably, the glass fiber is chopped glass fiber surface-treated with a silane coupling agent.

[0028] Preferably, the chain extender is an epoxy chain extender.

[0029] Preferably, the nucleating agent is at least one of a sodium salt of a C28-C32 linear saturated carboxylic acid and talc.

[0030] Preferably, the lubricant is pentaerythritol stearate.

[0031] Preferably, the antioxidant is at least one of antioxidant 1010, antioxidant 168, and antioxidant 3114.

[0032] Preferably, the weight portion of the waste PET is 65-70 parts, the weight portion of the chain extender is 0.5-1.5 parts, the weight portion of the nucleating agent is 0.1-1 parts, the weight portion of the lubricant is 0.1-1 parts, the weight portion of the antioxidant is 0.05-0.15 parts, and the weight portion of the glass fiber is 25-35 parts.

[0033] Further preferably, the weight portion of the waste PET is 68.1 parts, the weight portion of the chain extender is 0.8 parts, the weight portion of the nucleating agent is 0.5 parts, the weight portion of the lubricant is 0.5 parts, the weight portion of the antioxidant is 0.1 parts, and the weight portion of the glass fiber is 30 parts.

[0034] Preferably, the mixing is carried out by using a high-speed mixer, the mixing speed is 500-700 rpm, and the mixing time is 2-4 min.

[0035] Preferably, the screw speed of the extruder during the heating extrusion is 250-350 rpm.

[0036] Preferably, the temperature of the heated extrusion is 200-270°C.

[0037] Further preferably, the heating temperature zones are set as: 200°C for the first zone, 270°C for the second zone, 270°C for the third zone, 270°C for the fourth zone, 270°C for the fifth zone, 265°C for the sixth zone, 265°C for the seventh zone, 265°C for the eighth zone, 265°C for the ninth zone, 265°C for the tenth zone, 265°C for the eleventh zone, and 270°C for the head.

[0038] In a third aspect, the present invention provides a waste PET composite material prepared by the above-mentioned method for preparing the waste PET composite material.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention mainly optimizes the equipment for preparing modified PET engineering plastics by extruding waste PET as raw materials and adding glass fiber through an extruder: (1) three exhaust systems are set at specific positions on the extruder barrel. Compared with conventional equipment, the exhaust efficiency of chain extension reaction byproducts and water is greatly improved, the chain extension reaction is promoted to proceed in the positive direction, and the possibility of PET hydrolysis caused by water is reduced, so that a PET composite material with higher molecular weight and better material performance can be obtained; (2) a suitable side feed port is set on the extruder to feed glass fiber, so that the glass fiber is well sheared and dispersed, and will not be sheared too finely, and the exhaust effect is not affected, so as to obtain a material with better performance. The preparation equipment of the present invention can achieve the goal of taking into account stable material production, good appearance of the product, high material molecular weight, and good heat resistance, and has high application value in the recycling of waste PET. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The schematic diagram of the structure of the preparation equipment of the waste PET composite material of the present invention, wherein the reference numbers in the figure are: 100-main feeding port, 200-barrel (201-first port of the barrel, 202-second port of the barrel), 300-screw, 401-first exhaust system, 402-second exhaust system, 403-third exhaust system, 500-side feeding port;

[0042] Figure 2 It is a schematic diagram of the connection positions of the barrel exhaust system and the side feeding port in the preparation equipment of the waste PET composite material of the present invention;

[0043] Figure 3 It is a schematic diagram showing that the production of the waste PET composite material and the preparation device and method thereof of the present invention is normal and stable;

[0044] Figure 4 This is a schematic diagram of the normal appearance of the injection molded parts produced by the waste PET composite material and the preparation equipment and method of the present invention. DETAILED DESCRIPTION

[0045] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention will be further described below in conjunction with specific examples. The test methods used in the following examples are conventional methods unless otherwise specified; the materials and reagents used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0046] Examples 1-5

[0047] Examples 1-5 are examples of the equipment and method for preparing the waste PET composite material of the present invention.

[0048] The schematic diagram of the structure of the preparation equipment of the waste PET composite material in Examples 1-5 is as follows Figure 1 :

[0049] The waste PET composite material preparation equipment used is a meshing parallel co-rotating twin-screw extruder, the main structure of which includes: a main feeding port 100, a barrel 200, a screw 300, a first exhaust system 401, a second exhaust system 402, a third exhaust system 403, and a side feeding port 500; wherein, the main feeding port 100, the first exhaust system 401, the second exhaust system 402, the side feeding port 500 and the third exhaust system 403 are sequentially arranged on the barrel body starting from the first port 201;

[0050] The screw length-diameter ratio of the meshing parallel co-rotating twin-screw extruder used in Examples 1-5 is 48:1, and the exhaust system used is a vacuum exhaust system with a vacuum degree range of -0.06MPa to -0.1MPa; the schematic diagram of the connection position range of the exhaust system and the side feed port on the extruder barrel is as shown in Figure 2 As shown; wherein, L refers to the length from the first port of the barrel (i.e. the starting end of the barrel) to the second port of the barrel (i.e. the end of the barrel), and the position of the exhaust system and the side feeding port is calculated by the length of the position where they are installed and connected on the barrel from the first port and the proportional relationship with the total length L of the barrel.

[0051] The specific positions of the exhaust system and the side feed port in Examples 1-5 are shown in Table 1 below.

[0052] The method for preparing the waste PET composite material using the preparation equipment of the waste PET composite material described in Examples 1-5 is as follows:

[0053] (1) Prepare the raw materials, which are as follows, by weight: 68.1 parts of waste PET bottle flakes, 30 parts of glass fiber, 0.8 parts of chain extender, 0.5 parts of nucleating agent, 0.5 parts of lubricant, and 0.1 parts of antioxidant; wherein the glass fiber is short-cut glass fiber surface-treated with a silane coupling agent, the chain extender is an epoxy chain extender, the nucleating agent is a sodium salt of carboxylic acid, the lubricant is pentaerythritol stearate, and the antioxidant is antioxidant 1010.

[0054] (2) Dry the waste PET bottle flakes at 120°C for 4 hours.

[0055] (3) The raw materials except glass fiber in the preparation are mixed uniformly. The specific steps are as follows: use a high-speed mixer to mix the materials. First, add half of the waste PET bottle flakes, then add the chain extender, nucleating agent, lubricant, and antioxidant in order, and finally add the remaining half of the waste PET bottle flakes. After the addition of materials is completed, start mixing. The high-speed mixer blade speed is 600 rpm and the mixing time is 3 minutes.

[0056] (4) After the mixing is completed, the obtained mixed material is fed into the main feeding port of the above-mentioned corresponding equipment, and the glass fiber is fed into the side feeding port to start extrusion production. The temperature of each zone of the extruder is set as follows: first zone 200°C / second zone 270°C / third zone 270°C / fourth zone 270°C / fifth zone 270°C / sixth zone 265°C / seventh zone 265°C / eighth zone 265°C / ninth zone 265°C / tenth zone 265°C / eleventh zone 265°C / die head 270°C, and the screw speed of the extruder is 300rpm.

[0057] (5) The material discharged from the die of the extruder is drawn into strips, cooled, and pelletized to obtain finished particles of the waste PET composite material.

[0058] Table 1 Location of exhaust system and side feed port in the preparation equipment of Examples 1-5

[0059]

[0060] Comparative Examples 1-7

[0061] The difference between the preparation equipment of the waste PET composite material in Comparative Examples 1-7 and that in the embodiment is that the setting and installation of the exhaust system or the side feeding port in the equipment are changed, as shown in Table 2.

[0062] Referring to the preparation method of the embodiment, the waste PET composite material was prepared by using the preparation equipment in Comparative Examples 1-7.

[0063] Table 2 Location of exhaust system and side feed port in the preparation equipment of Comparative Examples 1-7

[0064]

[0065] Effect Example 1

[0066] In order to explore the specific effect of preparing the waste PET composite material by the preparation device and method of the waste PET composite material provided by the present invention, the production conditions in the embodiments and comparative examples, as well as the appearance, heat deformation temperature and intrinsic viscosity of the injection molded parts of the prepared waste PET composite material were tested:

[0067] The production situation is evaluated as follows: observe whether there are broken strips of material discharged from the die of the extruder during the preparation process;

[0068] The evaluation of the appearance of injection molded parts is as follows: the waste PET composite material is melted, injected into the plastic product mold by pressure, cooled and molded to obtain the injection molded parts, and the appearance is observed to see whether it is normal or has obvious floating fibers;

[0069] The test method for heat deformation temperature refers to GB / T 1633-2000; the test method for intrinsic viscosity refers to GB / T14190-2017.

[0070] The results are shown in Table 3. The schematic diagram of the production of the waste PET composite material preparation equipment and method in Example 2 of the present invention is as follows: Figure 3 ; The schematic diagram of the obtained waste PET composite injection molded parts with normal appearance and no floating fibers is as follows Figure 4 .

[0071] From Table 3, we can see that:

[0072] (1) From the comparison of the results of the embodiment and the comparative example, it can be seen that the preparation equipment of the waste PET composite material provided by the present invention is respectively provided with three exhaust systems and a side feeding port for feeding glass fiber at specific positions of the equipment. The composite material is prepared by adding waste PET to glass fiber, which can timely discharge the by-products of the chain extension reaction, improve the molecular weight of the composite material, and achieve good dispersion of the glass fiber, further optimize the product performance. It is observed that the production conditions are normal and stable without broken strips. The injection molded parts of the prepared waste PET composite material have a normal appearance without floating fibers, and the heat deformation temperature is ≥237°C and the intrinsic viscosity is above 0.94 dL / g. Its heat resistance and intrinsic viscosity are significantly better than those of the comparative example. Among them, the equipment scheme of Example 2 can achieve the best heat resistance and chain extension effect.

[0073] (2) By comparing the examples and comparative examples 1-3, it can be seen that the three exhaust systems provided in the present invention are indispensable. In comparative examples 1-3, 1-2 of the exhaust systems are closed, which leads to broken strips and poor stability during production. At the same time, the intrinsic viscosity of the obtained material is significantly reduced, the molecular weight is reduced, and the chain extension effect is poor. At the same time, compared with Example 2, when the installation positions of the three exhaust systems in Examples 3-5 are changed in a single manner, the molecular weight of the obtained waste PET composite material is also affected to a certain extent. The specific installation position of the exhaust system affects the discharge of by-products in the chain extension reaction, thereby affecting the molecular weight of the product.

[0074] (3) By comparing Examples 1-2 and Comparative Examples 4-7, it can be seen that the setting of the position of the side feeding port for feeding glass fibers has a significant effect on the performance enhancement effect of the waste PET composite material prepared by the present invention. In Examples 1 and 2, the side feeding port is set between the second exhaust system and the third exhaust system, within the specified range of the present invention, the intrinsic viscosity can reach 1.05 dL and the heat deformation temperature can reach 240°C. In contrast, in Comparative Example 4, the side feeding port is set near the first port of the barrel, and the heat deformation temperature of the composite material obtained is greatly reduced to 83°C, and the intrinsic viscosity is significantly reduced. In Comparative Example 5, the side feeding port is set between the first exhaust system and the second exhaust system, and occasional broken strips occur during production, and the heat deformation temperature of the composite material is greatly reduced to 126°C, and the intrinsic viscosity is significantly reduced. In Comparative Examples 6 and 7, the side feeding port is set between the second exhaust system and the third exhaust system, outside the specified range of the present invention, and closer to the second exhaust system and the third exhaust system, all of which lead to a decrease in intrinsic viscosity and heat deformation temperature. When the side feeding port is set too close to the third exhaust system, serious broken strips occur during production, and the appearance of the injection molded parts of the composite material has obvious floating fibers. It can be seen that the present invention selects a suitable side feeding port setting position, which has a good improvement effect on the production of waste PET composite materials, the heat resistance of the materials, the molecular weight and other important application properties.

[0075] Table 3 Production conditions of the embodiments and comparative examples and test performance results of the obtained waste PET composite materials

[0076]

[0077] The preparation equipment of the waste PET composite material of the present invention is mainly aimed at the process of preparing PET composite material by adding glass fiber to waste PET, and adopts the technical scheme of setting three exhaust systems to efficiently discharge the byproducts of the chain extension reaction, so as to obtain a waste PET composite material with larger molecular weight and better performance; while the prior art does not put forward requirements for the exhaust system of the extruder, which is generally single vacuum exhaust, and the exhaust efficiency of the byproducts of the chain extension reaction is not high, the molecular weight of the obtained PET is lower, and the material performance is also lower. At the same time, the scheme of the present invention is preferably for the position of the glass fiber side feed port, which not only ensures the good and uniform dispersion of the glass fiber, but also prevents the glass fiber from being sheared too much, so as to achieve the improvement of material performance; and under the condition of setting three exhaust systems, the position of the side feed port also needs to consider that it cannot affect the vacuum effect, and the technical scheme of the present invention well meets the higher requirements for the position of the side feed port under this premise. In summary, the present invention overcomes the problems existing in the prior art, and provides a preparation equipment and method strategy for waste PET composite materials that can achieve stable production, good product heat resistance, high molecular weight, and injection molded parts that meet the application requirements, and has high application value in the recycling and reuse of waste PET.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A preparation device for waste PET composite materials, characterized in that: The preparation equipment of the waste PET composite material is an extruder, comprising a barrel and a screw arranged in the barrel, the barrel comprising a first port and a second port; the aspect ratio of the screw is (47-49): 1; The barrel body of the barrel is provided with a main feeding port, a first exhaust system, a second exhaust system, a side feeding port and a third exhaust system in sequence from the first port; the total length of the barrel is L, and the distance between the connection between the first exhaust system and the barrel and the first port is 0.25L-0.33L; the distance between the connection between the second exhaust system and the barrel and the first port is 0.42L-0.5L; the distance between the connection between the side feeding port and the barrel and the first port is 0.58L-0.75L; the distance between the connection between the third exhaust system and the barrel and the first port is 0.83L-0.92L.

2. The preparation equipment of waste PET composite material as claimed in claim 1, characterized in that: The screw is constructed as meshing parallel co-rotating twin screws.

3. The preparation equipment of waste PET composite material as claimed in claim 1, characterized in that: The exhaust system is a vacuum exhaust system.

4. The preparation equipment of waste PET composite material as claimed in claim 3, characterized in that: The vacuum degree of the vacuum exhaust system is -0.1-(-0.06)MPa.

5. A method for preparing a waste PET composite material, characterized in that: The method is prepared by using the preparation equipment of the waste PET composite material as claimed in any one of claims 1 to 4, comprising the following steps: The waste PET, chain extender, nucleating agent, lubricant and antioxidant are mixed and fed into the main feeding port, and the glass fiber is fed into the side feeding port. After heating and extrusion, the waste PET composite material is obtained by drawing, cooling and pelletizing.

6. The method for preparing the waste PET composite material according to claim 5, characterized in that: The weight portion of the waste PET is 65-70 parts, the weight portion of the chain extender is 0.5-1.5 parts, the weight portion of the nucleating agent is 0.1-1 parts, the weight portion of the lubricant is 0.1-1 parts, the weight portion of the antioxidant is 0.05-0.15 parts, and the weight portion of the glass fiber is 25-35 parts.

7. The method for preparing the waste PET composite material according to claim 5, characterized in that: The screw speed of the extruder during the heating extrusion is 250-350 rpm.

8. The method for preparing the waste PET composite material according to claim 5, characterized in that: The temperature of the heated extrusion is 200-270°C.

9. The waste PET composite material prepared by the method for preparing the waste PET composite material according to any one of claims 5 to 8.

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