A thermoplastic resin recycling co-extrusion device

Abstract

The utility model relates to thermoplastic resin coextrusion preparation technical field, concretely relates to a kind of recycling thermoplastic resin coextrusion device.The recycling thermoplastic resin coextrusion device of the utility model, the coextrusion device is configured as recycling thermoplastic resin film coextrusion forming thermoplastic resin composite film, the coextrusion device includes main extruder and vice extruder, the main extruder is configured as extrusion forming new material layer, the vice extruder is configured as extrusion forming recycled material layer;Wherein, the ratio of the screw diameter of the main extruder and the screw diameter of the vice extruder is (70~80) : (30~50).The recycling thermoplastic resin coextrusion device provided by the utility model, the coextrusion device is used to recycle thermoplastic resin film to reuse coextrusion forming thermoplastic resin composite film, the performance of thermoplastic resin composite film extrusion formed using the device is excellent, and its performance can approach or reach the use requirement of interlayer glass with intermediate film or photovoltaic packaging film.

Description

Technical Field

[0001] This utility model relates to the field of thermoplastic resin co-extrusion preparation technology, and specifically to a thermoplastic resin recycling co-extrusion device. Background Technology

[0002] Polyvinyl butyral (PVB) interlayer film is a core material for laminated glass or photovoltaic cell encapsulation, with a global annual demand exceeding 1 million tons. However, scrap and waste generated during the production process account for as much as 8-12%. PVB scrap and waste are generally recycled through physical recycling, chemical recycling, or chemical depolymerization. Physical recycling is relatively complex, and the recycled material is difficult to reuse in the laminated glass or photovoltaic cell encapsulation industry. Chemical recycling or chemical depolymerization requires the addition of a series of chemical reagents and complex chemical reactions, making the process complex and technically challenging. In existing technologies, to address the issue of reduced performance from recycled materials, PVB recycled materials are blended with PE, PP, or PVB powder. However, blending leads to problems such as decreased light transmittance and increased haze in the film material.

[0003] To address the above issues, there is an urgent need to invent a thermoplastic resin co-extrusion device for recycling thermoplastic resins, in order to solve the problem of recycling and reusing waste or scraps of thermoplastic resin films such as PVB films. Utility Model Content

[0004] This invention provides a co-extrusion device for recycling thermoplastic resins, aiming to solve the problem of recycling and reusing waste or scraps of thermoplastic resin films such as PVB films.

[0005] To achieve the above technical objectives, this application adopts the following technical solution.

[0006] A co-extrusion apparatus for recycling thermoplastic resin is disclosed, the co-extrusion apparatus being configured to co-extrude recycled thermoplastic resin film into thermoplastic resin composite film. The co-extrusion apparatus includes a main extruder and an auxiliary extruder, the main extruder being configured to extrude a virgin material layer, and the auxiliary extruder being configured to extrude a recycled material layer; wherein the ratio of the screw diameter of the main extruder to the screw diameter of the auxiliary extruder is (70~80):(30~50).

[0007] According to the above-described thermoplastic resin co-extrusion apparatus, the thermoplastic resin composite film includes the virgin material layer and the recycled material layer, and the thickness ratio of the virgin material layer to the recycled material layer is (3~5):(1~2).

[0008] According to the above-described thermoplastic resin co-extrusion apparatus, the thickness of the new material layer is 0.1mm-1mm.

[0009] According to the above-described thermoplastic resin co-extrusion device, the screw length to diameter ratio of the main extruder is (35~45):1, and the screw length to diameter ratio of the auxiliary extruder is (25~32):1.

[0010] According to the above-described thermoplastic resin co-extrusion device, the co-extrusion device further includes a loss-in-weight feeder and a volumetric feeder. The loss-in-weight feeder is connected to the main extruder, and the volumetric feeder is connected to the auxiliary extruder. A first thermoplastic resin powder is added to the main extruder through the loss-in-weight feeder, and thermoplastic resin film / sheet material and / or a second thermoplastic resin powder are added to the auxiliary extruder through the volumetric feeder.

[0011] According to the above-described thermoplastic resin co-extrusion device for recycling thermoplastic resin, the size of the first thermoplastic resin powder is 20 mesh to 200 mesh, the size of the thermoplastic resin film sheet is 2 mm to 15 mm, and the size of the second thermoplastic resin powder is 20 mesh to 200 mesh. The first thermoplastic resin powder and the second thermoplastic resin powder can be of the same type and the same thermoplastic resin. Preferably, the size of the second thermoplastic resin is 40 mesh to 200 mesh.

[0012] According to the above-described thermoplastic resin co-extrusion apparatus, the co-extrusion apparatus further includes a distributor and a co-extrusion die, wherein the main extruder and the auxiliary extruder are respectively connected to the co-extrusion die via the distributor.

[0013] According to the above-described thermoplastic resin co-extrusion apparatus, the co-extrusion apparatus further includes a roller pressing device, which includes at least one set of rollers, and is configured to perform one or more of the following on the thermoplastic resin composite film: embossing, cooling, heat treatment, thinning, and leveling.

[0014] According to the above-described thermoplastic resin co-extrusion apparatus, the co-extrusion apparatus further includes a first zone temperature control system and a second zone temperature control system. The first zone temperature control system is configured to heat the main extruder in stages, and the second zone temperature control system is configured to heat the auxiliary extruder in stages.

[0015] According to the above-described thermoplastic resin recycling co-extrusion device, the main extruder is a single-screw extruder or a twin-screw extruder, and the auxiliary extruder is a single-screw extruder or a twin-screw extruder.

[0016] Compared with the prior art, the present invention has the following technical effects: This invention provides a co-extrusion apparatus for recycling thermoplastic resin. This apparatus is used to recycle recycled thermoplastic resin films (such as recycled PVB film) and co-extrude them into thermoplastic resin composite films. The co-extrusion apparatus includes a main extruder and a secondary extruder. The main extruder is configured to extrude a virgin material layer, and the secondary extruder is configured to extrude a recycled material layer. The virgin and recycled material layers are extruded through a co-extrusion die to form a thermoplastic resin composite film. The initially formed thermoplastic resin composite film is then further laminated, leveled, cooled, and embossed using a roller press. The thermoplastic resin composite film extruded using this apparatus exhibits excellent performance, approaching or meeting the performance requirements for interlayer films in laminated glass or photovoltaic encapsulation films.

[0017] Other features and advantages of the present invention will become clear from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This diagram illustrates the structure of a co-extrusion device for recycling thermoplastic resin according to an embodiment of the present invention.

[0020] Figure 2 This diagram shows a cross-sectional structure of the thermoplastic resin composite film in an embodiment of the present invention.

[0021] In the picture: 1. Main extruder; 2. Auxiliary extruder; 3. Loss-in-weight feeder; 4. Volume feeder; 31. Fresh material layer; 32. Recycled material layer; 5. Distributor; 6. Co-extrusion die; 7. Roller rollers; 8. First zone temperature control system; 9. Second zone temperature control system; 10. Feeding device. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present utility model or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0023] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0024] In the description of this utility model, it should be understood that the use of terms such as "first" and "second" to define the components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this utility model.

[0025] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0026] Please see Figure 1 A co-extrusion apparatus for recycling thermoplastic resin is disclosed. The co-extrusion apparatus is configured to co-extrude recycled thermoplastic resin film into a thermoplastic resin composite film 3. The co-extrusion apparatus includes a main extruder 1 and a secondary extruder 2. The main extruder 1 is configured to extrude a virgin material layer 31, and the secondary extruder 2 is configured to extrude a recycled material layer 32. The ratio of the screw diameter of the main extruder 1 to the screw diameter of the secondary extruder 2 is (70~80):(30~50). For example, the screw diameter of the main extruder is 75 mm, and the diameter of the secondary extruder screw, matching the 75 mm diameter of the main extruder, is 35 mm or 45 mm.

[0027] In one specific embodiment, please refer to Figure 2 The thermoplastic resin composite film includes a virgin material layer 31 and a recycled material layer 32, and the thickness ratio of the virgin material layer 31 to the recycled material layer 32 is (3~5):(1~2). For example, the thickness ratio of the virgin material layer to the recycled material layer is 3:1, 4:1, 5:1, 3:2, 4:2, 5:2, etc. To ensure the performance of the thermoplastic resin composite film, the thickness of the virgin material layer is greater than the thickness of the recycled material layer. Simultaneously, the recycled material of the thermoplastic resin film can be reused.

[0028] In one specific embodiment, the thickness of the new material layer is 0.1mm-1mm. For example, the thickness of the new material layer is 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, and 1mm, etc.

[0029] In one specific embodiment, the screw length-to-diameter ratio of the main extruder is (35~45):1, and the screw length-to-diameter ratio of the auxiliary extruder is (25~32):1. For example, the screw length-to-diameter ratio of the main extruder is 40:1, and the corresponding auxiliary extruder has a screw length-to-diameter ratio of 28:1.

[0030] In one specific embodiment, the co-extrusion apparatus further includes a loss-in-weight feeder 3 and a volumetric feeder 4. The loss-in-weight feeder 3 is connected to the main extruder 1, and the volumetric feeder 4 is connected to the auxiliary extruder 2. A first thermoplastic resin powder is fed into the main extruder 1 via the loss-in-weight feeder 3, and thermoplastic resin film / sheet material and / or a second thermoplastic resin powder are fed into the auxiliary extruder 2 via the volumetric feeder 4. Specifically, the loss-in-weight feeder has high feeding precision, enabling accurate control of the feed amount of the new material layer, ensuring the thickness and uniformity of the new material layer, thereby ensuring various properties of the new material layer. The volumetric feeder has relatively low cost and is beneficial for feeding sheet materials, while also meeting the requirements for using recycled material layers. For example, PVB powder is added to the main extruder via a loss-in-weight feeder, while PVB film sheet is added to the auxiliary extruder via a volumetric feeder. It is understood that PVB powder is polyvinyl acetal resin powder. During film preparation, PVB powder cannot be directly molded; it requires the addition of plasticizers and other additives. Specifically, PVB powder is added to the main extruder via a loss-in-weight feeder, while the plasticizer is added via another feeding device. The PVB powder and plasticizer are thoroughly mixed under the action of the screw in the main extruder. To ensure thorough mixing of the PVB powder and plasticizer, the screw of the main extruder needs to meet a certain length requirement. Based on theoretical calculations and multiple experimental verifications, the diameter-to-length ratio of the main extruder screw is approximately 1:40. Under the condition of ensuring uniform mixing of PVB resin powder and plasticizer, the recycled PVB film sheet material already contains plasticizer and does not require additional plasticizers or other additives. It is directly added to the secondary extruder via a volumetric feeder. Since the recycled PVB film sheet material has an irregular polygonal shape, its flowability in the volumetric feeder is poor. To solve this problem, a small amount of PVB powder can be added to the PVB film sheet material. The amount of PVB powder added here does not exceed 10% of the weight of the PVB film sheet material. The addition of PVB powder can also improve the performance of the recycled material layer. It should be noted that the loss-in-weight feeder and volumetric feeder in this application are not particularly limited, and equipment commonly used in the industry or on the market can be used.

[0031] In one specific embodiment, the size of the first thermoplastic resin powder is 20 mesh to 200 mesh, the size of the thermoplastic resin film sheet is 2 mm to 15 mm, and the size of the second thermoplastic resin powder is 20 mesh to 200 mesh. The first thermoplastic resin powder and the second thermoplastic resin powder can be the same type of thermoplastic resin. Preferably, the size of the second thermoplastic resin is 100 mesh to 200 mesh. Specifically, the shape of the thermoplastic resin film sheet is irregular. It is generally obtained by crushing large recycled sheets into small pieces. The size of the thermoplastic resin film sheet mentioned in this utility model refers to the maximum length of the sheet being 2mm to 15mm. It can be understood that the size of the thermoplastic resin film sheet mentioned in this utility model is not strictly speaking, all thermoplastic resin sheets are between 2mm and 15mm in size. Rather, more than 90% are between 2mm and 15mm. It is not excluded that a small number of thermoplastic resin film sheets are larger than 15mm or smaller than 2mm. Furthermore, more than 50% of the thermoplastic resin film sheets are between 3mm and 10mm in size.

[0032] In one specific embodiment, the co-extrusion apparatus further includes a distributor 5 and a co-extrusion die 6, wherein the main extruder 1 and the auxiliary extruder 2 are respectively connected to the co-extrusion die 6 via the distributor 5.

[0033] In one specific embodiment, the co-extrusion apparatus further includes a composite unit comprising at least one set of rollers 7, the rollers being configured to perform one or more of the following on the thermoplastic resin composite film: embossing, cooling, heat treatment, thinning, and leveling.

[0034] In one specific embodiment, the co-extrusion apparatus further includes a first zone temperature control system 8 and a second zone temperature control system 9. The first zone temperature control system 8 is configured to heat the main extruder 1 in stages, and the second zone temperature control system 9 is configured to heat the auxiliary extruder 2 in stages. Specifically, both the first and second zone temperature control systems include a control system and a heating component, which can be a common heating element such as a heating wire. The first zone temperature control system is divided into nine zones for staged heating, with the heating range increasing from 150°C to 178°C. The second zone temperature control system is divided into eight zones for staged heating, with the heating range increasing from 150°C to 170°C. Using two zone temperature control systems can compensate for the difference in melt viscosity between thermoplastic resin powder and thermoplastic resin film / sheet material, reducing fluctuations at the co-extrusion die caused by the difference in melt viscosity between the two different materials. The pressure fluctuation at the co-extrusion die can be reduced to below ±3%.

[0035] In one specific embodiment, the main extruder is a single-screw extruder or a twin-screw extruder, and the auxiliary extruder is also a single-screw extruder or a twin-screw extruder. Preferably, the auxiliary extruder is a twin-screw extruder.

[0036] The following uses the recycling of PVB film as an example to illustrate the thermoplastic resin co-extrusion device for recycling provided by this utility model.

[0037] Please see Figure 1 and Figure 2A co-extrusion device for recycling PVB film includes a main extruder and an auxiliary extruder. The screw diameter of the main extruder is 75 mm, and the screw diameter of the auxiliary extruder is 35 mm. The length-to-diameter ratio of the main extruder screw is 40:1, and the length-to-diameter ratio of the auxiliary extruder screw is 28:1, where the length-to-diameter ratio is the ratio of the screw length to the screw diameter. PVB resin powder (PVB resin powder refers to polyvinyl butyral resin powder directly synthesized from PVA and butyraldehyde) is added to the main extruder using a loss-in-weight feeder. Plasticizer is added to the main extruder through a feeding device 10. Since the plasticizer is a viscous liquid, the feeding device uses a metering pump to pump the plasticizer from a container to the main extruder. The PVB resin powder and plasticizer are further mixed under the action of the screw in the main extruder and conveyed to the distributor. Due to the distance between the loss-in-weight feeder and the feeding device, there is a certain time difference between the addition of PVB powder and plasticizer. Before reuse, the recycled PVB resin film is pulverized to obtain PVB resin film sheets with a size of 2mm-15mm. To increase the lubrication performance of the PVB resin film sheets, a small amount of PVB resin powder is added during the pulverization process (the weight of the added PVB resin powder is 0.5%~5% of the PVB film sheets). Alternatively, after the PVB resin film is pulverized, a mixer is used to mix the PVB film sheets with a small amount of PVB powder. The PVB resin film sheets are then fed into the auxiliary extruder using a volume feeder. Under the action of the screw in the auxiliary extruder, the PVB resin film sheets and PVB powder are further mixed and conveyed to the distributor. Because the melt viscosity of PVB resin powder and PVB resin film sheet has a certain difference, a large viscosity difference can easily cause defects in the composite interface between the new material layer and the recycled material layer. To solve this problem, the main extruder and the auxiliary extruder use a first-zone temperature control system and a second-zone temperature control system, respectively, to heat the PVB resin powder and PVB resin film sheet in stages, with heating ranges of 150°C~178°C and 150°C~170°C, respectively. After heat treatment, the melt viscosity difference between the PVB resin powder and PVB resin film sheet is smaller. The reduction in the melt viscosity difference between the two also helps to reduce the fluctuation of the co-extrusion die pressure, reducing the fluctuation range to 2%.PVB resin powder and PVB resin film sheets, distributed by the distributor, are fed into corresponding channels of the co-extrusion die for extrusion into new and recycled material layers. Thermoplastic resin film is then extruded through the co-extrusion die. To improve the appearance and properties of the extruded thermoplastic resin film, the co-extrusion unit also includes a rolling mill consisting of multiple sets of rollers. The rolling mill is mainly used for one or more of the following processes on the thermoplastic resin composite film: embossing, cooling, heat treatment, thinning, and leveling. The number of roller pairs is determined according to actual needs. One or more roller pairs can perform cooling, heating, or leveling functions, which can be specifically determined based on actual requirements. Each set of roller pairs can have one, two, or more functions; for example, one set of roller pairs can perform both embossing and cooling functions. To improve the efficiency of the co-extrusion unit, a winding device is also installed at the downstream station of the rolling mill to wind up the rolled PVB resin film. After roll lamination, a PVB resin composite film containing a recycled material layer is obtained. The thickness of the virgin material layer is 0.293mm-0.302mm, and the thickness of the recycled material layer is 0.098-0.107mm. The light transmittance of the PVB resin composite film can reach more than 88%, and its tensile strength can reach more than 92% of that of the PVB resin composite film without the recycled material layer.

[0038] It is understood that the above examples only illustrate two-layer films. For three-layer or higher films, the specific structure of the distributor and the layout design of the flow channels within the co-extrusion die can be modified to extrude two or more layers of new or recycled material from the PVB resin powder or PVB resin film sheet. The specific structure of the distributor and the layout design of the flow channels within the co-extrusion die are existing technologies and will not be described in detail here.

[0039] The above description is only an exemplary embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A co-extrusion apparatus for recycling thermoplastic resin, characterized in that, The co-extrusion apparatus is configured to co-extrude recycled thermoplastic resin film into a thermoplastic resin composite film. The co-extrusion apparatus includes a main extruder and an auxiliary extruder. The main extruder is configured to extrude a virgin material layer, and the auxiliary extruder is configured to extrude a recycled material layer. The ratio of the screw diameter of the main extruder to the screw diameter of the auxiliary extruder is (70-80):(30-50). The co-extrusion apparatus further includes a loss-in-weight feeder and a volume feeder. The loss-in-weight feeder is connected to the main extruder, and the volume feeder is connected to the auxiliary extruder. A first thermoplastic resin powder is added to the main extruder through the loss-in-weight feeder, and thermoplastic resin film / sheet material and / or a second thermoplastic resin powder are added to the auxiliary extruder through the volume feeder. The thermoplastic resin composite film includes the virgin material layer and the recycled material layer, and the thickness ratio of the virgin material layer to the recycled material layer is (3-5):(1-2); The thickness of the new material layer is 0.1 mm to 1 mm; The length-to-diameter ratio of the screw of the main extruder is (35-45):1, and the length-to-diameter ratio of the screw of the auxiliary extruder is (25-32):

1. The first thermoplastic resin powder has a size of 20 mesh to 200 mesh, the thermoplastic resin film sheet has a size of 2 mm to 15 mm, and the second thermoplastic resin powder has a size of 20 mesh to 200 mesh.

2. The thermoplastic resin co-extrusion apparatus according to claim 1, characterized in that, The co-extrusion apparatus further includes a distributor and a co-extrusion die, wherein the main extruder and the auxiliary extruder are respectively connected to the co-extrusion die via the distributor.

3. The thermoplastic resin co-extrusion apparatus according to claim 1, characterized in that, The co-extrusion apparatus further includes a roller pressing device, which comprises at least one set of rollers and is configured to perform one or more processes on the thermoplastic resin composite film, such as embossing, cooling, heat treatment, thinning, and leveling.

4. The thermoplastic resin co-extrusion apparatus according to claim 1, characterized in that, The co-extrusion unit further includes a first zone temperature control system and a second zone temperature control system. The first zone temperature control system is configured to heat the main extruder in stages, and the second zone temperature control system is configured to heat the auxiliary extruder in stages.

5. The thermoplastic resin co-extrusion apparatus according to claim 1, characterized in that, The main extruder is a single-screw extruder or a twin-screw extruder, and the auxiliary extruder is a single-screw extruder or a twin-screw extruder.

Images