Preparation method of high-strength flame-retardant polyester material

Abstract

The invention provides a preparation method of a polyester material, which is a continuous process and comprises the following steps. The recycled release film is crushed, compacted and dried, and then is subjected to melt extrusion and degassing. And after filtering, tackifying by using a liquid tackifying system. The preparation method comprises the following steps: preparing a polyester material, then carrying out melt mulling, carrying out modification extrusion by using a modifier which comprises a nucleating agent, a flame retardant, an antioxidant, a rod-like filling reinforcing material and a compatilizer, and carrying out granulation and dehydration to prepare the polyester material.

Description

Technical Field

[0001] The present invention relates to a method for preparing a polyester material, and more particularly to a method for preparing a high-strength flame-retardant polyester material. Background Art

[0002] In the technical field of existing methods for preparing high-strength flame-retardant polyester materials, the kneading modification technology is off-line (non-continuous) extrusion kneading modification, mainly adopting a segmented process. More specifically, for example, a segmented method such as Process 1, Process 2, and Process 3 can be adopted. In Process 1, the recycled release film is crushed, the shredded film is compacted and dried, then melt extruded and degassed. After filtration, pelletizing, and dehydration, low-viscosity PET recycled pellets can be obtained. Then, Process 2 is carried out. In Process 2, the low-viscosity PET recycled pellets are respectively subjected to solid-state polymerization and kneading with an extender to form medium- and high-viscosity PET recycled pellets. Finally, Process 3 is carried out. In Process 3, the medium- and high-viscosity PET recycled pellets are melt-kneaded and extruded for modification with a modifier, and then pelletized and dehydrated to obtain a high-strength flame-retardant polyester material. That is, the existing method for preparing high-strength flame-retardant polyester materials mainly uses a segmented process of Process 1, Process 2, and Process 3 for off-line (non-continuous) extrusion kneading modification.

[0003] With the increasing emphasis on environmental awareness, international brands are gradually moving towards the trends of circular economy, energy conservation, and carbon reduction, with the important goal of introducing recycled materials with low carbon emissions into products. However, the existing method for preparing high-strength flame-retardant polyester materials using a segmented process is inefficient and energy-consuming, and does not conform to the global environmental protection trend of plastic reduction and energy conservation.

[0004] Based on the above, developing a method for preparing a high-strength flame-retardant polyester material to improve production efficiency and reduce energy consumption, and thus conform to the global environmental protection trend of plastic reduction and energy conservation, is an important research topic currently required. Summary of the Invention

[0005] The present invention provides a method for preparing a polyester material, mainly adopting a continuous process and performing melt-state feeding modification technology to reduce energy consumption waste caused by repeated heating and cooling, so it is more energy-efficient.

[0006] The method for preparing the polyester material of the present invention is a continuous process, including the following steps. The recycled release film is crushed and compacted and dried, then melt extruded and degassed. After filtration, viscosity increase is carried out using a liquid viscosity increasing system. Then, melt kneading is carried out, and modification and extrusion are carried out with a modifier, and then pelletized and dehydrated to produce a polyester material.

[0007] In one embodiment of the present invention, the method for preparing the polyester material further includes removing the surface coating of the recycled release film by a film surface ceramic slurry removal technique before crushing, compacting, and drying the recycled release film.

[0008] In one embodiment of the present invention, viscosity increasing is carried out by a liquid viscosity increasing system to increase the inherent viscosity (IV) from a viscosity range of 0.5 dl / g to 0.62 dl / g to a viscosity range of 0.7 dl / g to 0.9 dl / g.

[0009] In one embodiment of the present invention, the temperature for crushing, compacting, and drying the recycled release film is 100°C to 160°C.

[0010] In one embodiment of the present invention, the temperature for melt extrusion and degassing is 240°C to 280°C.

[0011] In one embodiment of the present invention, the temperature for melt kneading is 230°C to 275°C.

[0012] In one embodiment of the present invention, the temperature for modified extrusion is 230°C to 280°C.

[0013] In one embodiment of the present invention, the modifier includes a nucleating agent, a flame retardant, an antioxidant, a rod-shaped filler and reinforcing material, and a compatibilizer.

[0014] In one embodiment of the present invention, the nucleating agent includes an organic nucleating agent, an inorganic nucleating agent, or a blend thereof.

[0015] In one embodiment of the present invention, the organic nucleating agent includes organic sodium salts, and the organic sodium salts include sodium benzoate, sodium lignite, or ethylene-methacrylic acid copolymer (EMAA).

[0016] In one embodiment of the present invention, the inorganic nucleating agent includes inorganic micro-nano powder, and the inorganic micro-nano powder includes talc powder, titanium dioxide, silicon dioxide, or calcium carbonate.

[0017] In one embodiment of the present invention, the flame retardant includes a halogen-free flame retardant, and the halogen-free flame retardant includes a nitrogen-based flame retardant, a phosphorus-based flame retardant, or a composite blend thereof.

[0018] In one embodiment of the present invention, the antioxidant includes a hindered phenol antioxidant, a phenolic antioxidant, a mixed antioxidant, a phosphite antioxidant, a composite antioxidant, or a combination thereof.

[0019] In one embodiment of the present invention, the rod-shaped filler and reinforcing material includes silicone-modified glass fiber.

[0020] In one embodiment of the present invention, the compatibilizer includes ethylene-methyl acrylate-glycidyl methacrylate copolymer (E-MA-GMA), polyolefin elastomer grafted glycidyl methacrylate (POE-g-GMA), polyethylene grafted glycidyl methacrylate (PE-g-GMA), or a combination thereof.

[0021] In one embodiment of the present invention, based on the total weight of the polyester material, the addition amount of the nucleating agent is 0.5 wt% to 3 wt%, the addition amount of the flame retardant is 10 wt% to 18 wt%, the addition amount of the antioxidant is 0.1 wt% to 1 wt%, the addition amount of the rod-shaped filler reinforcing material is 25 wt% to 32 wt%, and the addition amount of the compatibilizer is 0.5 wt% to 5 wt%.

[0022] Based on the above, the present invention provides a method for preparing a polyester material, which mainly adopts a continuous process and performs a molten state feeding modification technology to reduce the energy consumption waste of repeated heating and cooling, so it is more energy-saving. In addition, the present invention improves the problems of slow crystallization speed, insufficient impact resistance and rigidity of PET materials through a kneading modification technology, so that it can be injection molded and applied to products such as industrial connectors, fans, sports equipment or battery and electrical appliance housings. Description of the Drawings

[0023] None Detailed Description of the Embodiments

[0024] Hereinafter, embodiments of the present invention will be described in detail. However, these embodiments are illustrative, and the disclosure of the present invention is not limited thereto.

[0025] In this article, a range represented by "one numerical value to another numerical value" is a summary representation method to avoid listing all numerical values in this range in the specification one by one. Therefore, the description of a specific numerical range covers any numerical value within this numerical range and a smaller numerical range defined by any numerical value within this numerical range, as if the arbitrary numerical value and the smaller numerical range are written out in the specification.

[0026] The present invention provides a method for preparing a polyester material, which is a continuous process and includes the following steps. First, the surface coating of the recycled release film is removed by a membrane surface ceramic slurry removal technique. Next, the recycled release film is crushed, compacted and dried, and then enters a melt extruder for melt extrusion and degassing. After filtration, continuous in-line viscosity increase is carried out by a liquid viscosity increasing system. Then, melt kneading is carried out, and modification extrusion is carried out with a modifier, and then pelletizing and dehydration are carried out to produce a high-strength flame-retardant and environmentally friendly polyester material, which meets the UL 94 test 1.2 mm V0 standard.

[0027] In this embodiment, a liquid tackifying system is used for tackifying so that the inherent viscosity (IV) increases from a viscosity range of 0.5 dl / g to 0.62 dl / g to a viscosity range of 0.7 dl / g to 0.9 dl / g. In this way, the mechanical properties, flame retardancy, and fluidity of the environmentally friendly recycled pellets can be comparable to those of the virgin pellets.

[0028] In this embodiment, the temperature for crushing, compacting, and drying the recycled release film is, for example, 100°C to 160°C, the temperature for melt extrusion and degassing is, for example, 240°C to 280°C, the temperature for melt kneading is, for example, 230°C to 275°C, and the temperature for modified extrusion is, for example, 230°C to 280°C.

[0029] In this embodiment, the modifier may include a nucleating agent, a flame retardant, an antioxidant, a rod-shaped filler and reinforcing material, and a compatibilizer. Hereinafter, the above various components will be described in detail.

[0030] Nucleating agent

[0031] In this embodiment, the nucleating agent may include an organic nucleating agent, an inorganic nucleating agent, or a blend thereof. The organic nucleating agent may include organic sodium salts, and the organic sodium salts may include sodium benzoate, sodium lignite, or ethylene-methacrylic acid copolymer (EMAA). The inorganic nucleating agent may include inorganic micro-nano powder, and the inorganic micro-nano powder may include talc powder, titanium dioxide, silica, or calcium carbonate. Based on the total weight of the polyester material, the addition amount of the nucleating agent is, for example, 0.5 wt% to 3 wt%. Preferably, for example, the organic nucleating agent is combined with the inorganic nucleating agent, and at this time, based on the total weight of the polyester material, the addition amount is, for example, 1 wt% to 2 wt%. Adding the nucleating agent can improve the crystallization and curing speed of the PET material, and thus improve its processability.

[0032] Flame retardant

[0033] In this embodiment, to meet the RoHS and halogen-free requirements of the product, the flame retardant is a halogen-free flame retardant, and the halogen-free flame retardant may include a nitrogen-based flame retardant, a phosphorus-based flame retardant, or a composite blend thereof. The phosphorus-based flame retardant may include dipentaerythritol phosphate melamine salt (MPP), ammonium polyphosphate (APP), tolyl xylene phosphate, or hypophosphite salts. The nitrogen-based flame retardant may include melamine cyanurate (MCA), melamine, etc. More specifically, the compounding effect of hypophosphite salts and melamine cyanurate (MCA) is better, and the weight ratio of hypophosphite salts to melamine cyanurate (MCA) is, for example, 3:1 to 1:1. Based on the total weight of the polyester material, the addition amount of the flame retardant is, for example, 10 wt% to 18 wt%. The flame retardant can inhibit the combustion of PET through surface carbonization and improve the flame retardant characteristics.

[0034] Antioxidant

[0035] In this embodiment, the antioxidant may include a hindered phenol antioxidant, a phenolic antioxidant, a mixed antioxidant, a phosphite antioxidant, a composite antioxidant, or a combination thereof. Based on the total weight of the polyester material, the addition amount of the antioxidant is, for example, 0.1 wt% to 1 wt%. The antioxidant can improve the heat resistance and processability of the material.

[0036] Rod-shaped filler reinforcing material

[0037] In this embodiment, the rod-shaped filler reinforcing material may include silicone-modified glass fibers. The surface modification with silicone can improve compatibility. The diameter of the glass fibers is, for example, 10 μm to 13 μm, and the cut strand length is, for example, 3 mm to 4 mm. Based on the total weight of the polyester material, the addition amount of the rod-shaped filler reinforcing material is, for example, 25 wt% to 32 wt%. The rod-shaped filler reinforcing material can effectively improve the impact strength and rigidity of the material. The improvement effect of physical properties is directly related to the dispersion degree of the rod-shaped reinforcing material. Therefore, a compatibilizer grafted with -GMA needs to be introduced simultaneously to improve the dispersion of the rod-shaped filler reinforcing material in PET.

[0038] Compatibilizer

[0039] In this embodiment, the compatibilizer includes ethylene-methyl acrylate-glycidyl methacrylate copolymer (E-MA-GMA), polyolefin elastomer grafted glycidyl methacrylate (POE-g-GMA), polyethylene grafted glycidyl methacrylate (PE-g-GMA), or a combination thereof. Based on the total weight of the polyester material, the addition amount of the compatibilizer is, for example, 0.5 wt% to 5 wt%. The compatibilizer can improve the compatibility between the rod-shaped filler reinforcing material and the PET resin to enhance the reinforcement effect of the material.

[0040] Hereinafter, the preparation method of the high-strength flame-retardant polyester material of the present invention will be described in detail by means of experimental examples. However, the following experimental examples are not intended to limit the present invention.

[0041] Experimental example

[0042] In order to prove that the preparation method of the polyester material proposed by the present invention can produce a high-strength flame-retardant and environmentally friendly polyester material, improve the flame-retardant properties, and solve the problems of slow crystallization rate, insufficient impact strength and rigidity, the following experimental example is specifically made.

[0043] Testing method

[0044] Specific gravity: ASTM D792

[0045] Tensile strength, elongation: ASTM D638

[0046] Flexural strength, flexural modulus: ASTM D790

[0047] Flame retardancy: UL94

[0048] Material property evaluation

[0049] Industrial components were tested using PBT + 30% GF, unmodified PET, recycled PET + 30% glass fiber, and the polyester material prepared by the preparation method of the present invention according to the above test method. The test results are listed in Table 1 below. Since the preparation method of the polyester material of the present invention has been described in detail above, it will not be repeated here. For the polyester material prepared by the preparation method of the present invention in Table 1, the preparation conditions are as follows: viscosity increase is carried out with a liquid viscosity increasing system, the inherent viscosity (IV) is increased to 0.8 dl / g, the temperature for crushing, compacting and drying the recycled release film is 120 °C, the temperature for melt extrusion and degassing is 255 °C, the temperature for melt kneading is 265 °C, and the temperature for modified extrusion is 270 °C; based on the total weight of the polyester material, the addition amount of the nucleating agent is 1.5 wt%, the addition amount of the flame retardant is 12 wt%, the addition amount of the antioxidant is 0.2 wt%, the addition amount of the rod-shaped filler reinforcing material is 30 wt%, and the addition amount of the compatibilizer is 2.5 wt%.

[0050] It can be seen from Table 1 below that the unmodified PET material cannot meet the requirements of industrial component products in terms of impact resistance, rigidity (flexural modulus), and flame retardancy. Although recycled PET + 30% glass fiber can meet the component physical property requirements, it has no flame retardant effect. In contrast, the polyester material prepared by the preparation method of the present invention has the same flame retardant and heat resistance characteristics as PBT + 30% glass fiber for industrial components, and at the same time has good mechanical properties, meeting the UL 94 test 1.2 mm V0 standard. Moreover, through the modification with the nucleating agent and the rod-shaped filler reinforcing material, the problems of slow crystallization speed and insufficient strength are improved.

[0051] Table 1

[0052]

[0053] In summary, the present invention provides a preparation method for a polyester material, which mainly adopts a continuous process and carries out melt-state feeding modification technology to reduce the energy consumption waste of repeated temperature rise and fall, so it is more energy-saving. In this way, the problems of low efficiency and high energy consumption in the segmented process of the existing preparation method for high-strength flame-retardant polyester materials can be effectively improved. In addition, the present invention improves the problems of slow crystallization speed, insufficient impact strength and rigidity of PET materials through kneading modification technology, making it applicable to injection molding for products such as industrial connectors, fans, sports equipment or battery and electrical appliance housings. On the other hand, the present invention uses recycled release film as the PET raw material, and its mechanical properties, flame retardancy and fluidity are equivalent to those of virgin pellets. Therefore, it will contribute to the goal of global plastic reduction and energy conservation.

Claims

1. A method for preparing a polyester material, characterized in that, it is a continuous process, including: crushing, compacting and drying the recycled release film, followed by melt extrusion and degassing; after filtration, viscosity increase is carried out with a liquid viscosity increasing system; and melt kneading is carried out, and modification extrusion is carried out with a modifier, the modifier includes a nucleating agent, a flame retardant, an antioxidant, a rod-shaped filler reinforcing material and a compatibilizer, and then pelletizing and dehydration are carried out to produce the polyester material.

2. The method for preparing a polyester material according to claim 1, characterized in that, it further includes removing the surface coating of the recycled release film by a film surface ceramic slurry removal technique before crushing, compacting and drying the recycled release film.

3. The method for preparing a polyester material according to claim 1, characterized in that, viscosity increase is carried out with the liquid viscosity increasing system to increase the inherent viscosity from a viscosity range of 0.5 dl / g to 0.62 dl / g to a viscosity range of 0.7 dl / g to 0.9 dl / g.

4. The method for preparing a polyester material according to claim 1, characterized in that, the temperature for crushing, compacting and drying the recycled release film is 100°C to 160°C.

5. The method for preparing a polyester material according to claim 1, characterized in that, the temperature for melt extrusion and degassing is 240°C to 280°C.

6. The method for preparing a polyester material according to claim 1, characterized in that, the temperature for melt kneading is 230°C to 275°C.

7. The method for preparing a polyester material according to claim 1, characterized in that, the temperature for modification extrusion is 230°C to 280°C.

8. The method for preparing a polyester material according to claim 1, characterized in that, the nucleating agent includes an organic nucleating agent, an inorganic nucleating agent or a blend thereof.

9. The method for preparing a polyester material according to claim 8, characterized in that, the organic nucleating agent includes organic sodium salts, and the organic sodium salts include sodium benzoate, sodium lignite or ethylene-methacrylic acid copolymer.

10. The method for preparing a polyester material according to claim 8, characterized in that, the inorganic nucleating agent includes inorganic micro-nano powder, and the inorganic micro-nano powder includes talc powder, titanium dioxide, silicon dioxide or calcium carbonate.

11. The method for preparing a polyester material according to claim 1, characterized in that, the flame retardant includes a halogen-free flame retardant, and the halogen-free flame retardant includes a nitrogen-based flame retardant, a phosphorus-based flame retardant or a composite blend thereof.

12. The method for preparing a polyester material according to claim 1, characterized in that, the antioxidant includes a hindered phenol antioxidant, a phenolic antioxidant, a mixed antioxidant, a phosphite antioxidant, a composite antioxidant or a combination thereof.

13. The method for preparing a polyester material according to claim 1, characterized in that, the rod-shaped filler reinforcing material includes glass fiber modified by siloxane.

14. The method for preparing a polyester material according to claim 1, characterized in that, The compatibilizer includes ethylene-methyl acrylate-glycidyl methacrylate copolymer, polyolefin elastomer grafted with glycidyl methacrylate, polyethylene grafted with glycidyl methacrylate, or a combination thereof.

15. The method for preparing the polyester material according to claim 1, characterized in that based on the total weight of the polyester material, the addition amount of the nucleating agent is 0.5 wt% to 3 wt%, the addition amount of the flame retardant is 10 wt% to 18 wt%, the addition amount of the antioxidant is 0.1 wt% to 1 wt%, the addition amount of the rod-shaped filling and reinforcing material is 25 wt% to 32 wt%, and the addition amount of the compatibilizer is 0.5 wt% to 5 wt%.

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