Optimization process for preparing hydrolysis-resistant PET master batch

Abstract

The invention discloses an optimization process for preparing hydrolysis-resistant PET (polyethylene terephthalate) master batch. The optimization process comprises the following steps: S1, pretreating raw materials; s2, low-temperature pre-dispersion: adding the dried raw materials weighed according to the formula proportion into a high-speed mixer, so that the anti-hydrolysis agent and the auxiliary agent are uniformly attached to the surface of the PET base material to form a premix; s3, mild extrusion granulation: melting and mixing the premix through a twin-screw extruder, and extruding the premix into filaments through a die head; s4, the filaments are rapidly cooled and shaped through a cooling water tank, and secondary cross-linking is avoided; s5, pelletizing by adopting a pelletizer to obtain primary master batches; s6, the primary master batch is subjected to vacuum drying, surface moisture is removed, and the anti-hydrolysis PET master batch is obtained.The thermal degradation of a PET base material and the advanced reaction of an anti-hydrolysis agent are reduced, the intrinsic viscosity of the master batch is stable, and the anti-hydrolysis efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and specifically relates to an optimized process for preparing hydrolysis-resistant PET masterbatch. Background Technology

[0002] Polyethylene terephthalate (PET) is a high-performance thermoplastic polyester material with a highly symmetrical molecular structure. It is easy to crystallize and orient during processing, and has excellent film-forming properties, moldability, creep resistance, fatigue resistance, abrasion resistance and electrical insulation. At the same time, it has good weather resistance and chemical resistance, and is widely used in many fields such as fiber spinning, film and sheet materials, packaging bottles, electronic appliances, and automotive parts.

[0003] The ester bonds in PET are decomposed by water under high temperature and high humidity conditions, leading to molecular chain breakage. The molecular chain breakage directly causes the degradation of mechanical properties, such as a decrease in tensile strength and elongation at break, accompanied by material embrittlement, pulverization or cracking.

[0004] Adding carbodiimide anti-hydrolysis agents can improve the hydrolysis resistance of PET materials. Carbodiimide anti-hydrolysis agents are mostly added to PET materials in the form of masterbatch. Currently, masterbatch preparation is carried out by twin-screw extrusion at high temperature. This melt extrusion process will cause functional group degradation and reduce the hydrolysis resistance efficiency. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to overcome the shortcomings of the prior art and provide an optimized process for preparing hydrolysis-resistant PET masterbatch.

[0006] Technical solution: An optimized process for preparing hydrolysis-resistant PET masterbatch, comprising the following steps: S1. Raw material pretreatment: Vacuum dry the PET substrate slices to control the moisture content ≤0.05% to avoid hydrolysis; Vacuum dry the polymeric carbodiimide anti-hydrolysis agent, dispersant, anti-crosslinking agent, heat stabilizer, and antioxidant separately to remove moisture and volatile impurities; The raw materials for PET substrate chips include the following components by weight: 70-85 parts PET substrate, 10-20 parts polymeric carbodiimide anti-hydrolysis agent, 2-5 parts dispersant, 1-3 parts anti-crosslinking agent, 0.5-2 parts heat stabilizer, and 0.3-1 parts antioxidant. The PET substrate uses PET chips with an intrinsic viscosity of 0.65-0.85 dL / g, employing random copolymer PET or homopolymer PET to ensure compatibility between the masterbatch and the subsequent processed substrate. The polymeric carbodiimide anti-hydrolysis agent has a number average molecular weight of 5000-20000 g / mol and a carbodiimide group content of 8-12 mmol / g, selected from one or a combination of two of poly(1,3-phenylene carbodiimide) and poly(4,4'-methylenediphenylcarbodiimide) to avoid small molecule precipitation. To ensure the long-term resistance to hydrolysis; the dispersant is selected from one or more of ethylene acrylate copolymer (EAA), polyethylene glycol (PEG) with a molecular weight of 2000-6000 g / mol, and calcium stearate, to improve the uniformity of the dispersion of the anti-hydrolysis agent in the PET substrate; the anti-crosslinking agent is selected from monofunctional epoxy compounds, including glycidyl ether and epoxidized soybean oil, which inhibit the crosslinking reaction of polymeric carbodiimide with PET ester bonds by selectively reacting with the active groups of the polymeric carbodiimide; the heat stabilizer is selected from phosphite compounds, including tris(2,4-di-tert-butylphenyl) phosphite, to inhibit the thermal degradation of PET during processing; the antioxidant is selected from hindered phenolic antioxidants 1010 or 1076, used to delay the oxidative aging of the material and improve color stability; S2. Low-temperature pre-dispersion: Weigh the dried raw materials according to the formula ratio and add them to a high-speed mixer to make the anti-hydrolysis agent and additives evenly adhere to the surface of the PET substrate to form a premix; during the mixing process, the temperature is controlled not to exceed 80°C by cooling with a jacket to avoid premature reaction; S3. Mild Extrusion Granulation: The premix is ​​added to a twin-screw extruder, and the extrusion process parameters are set as follows: screw speed: 100-150 r / min; barrel zone 1 temperature: 180-200℃, barrel zone 2 temperature: 230-250℃, barrel zone 3 temperature: 250-260℃, barrel zone 4 temperature: 255-265℃, die head temperature: 260-270℃; vacuum degree: -0.08--0.09 MPa, used to promptly remove volatiles; the premix is ​​melted and mixed in the twin-screw extruder, and then extruded into filaments through the die head; S4. The filaments are rapidly cooled and shaped in a cooling water tank to avoid secondary cross-linking; S5. Pelletize the raw masterbatch using a pelletizer; S6. Vacuum dry the primary masterbatch to remove surface moisture and obtain hydrolysis-resistant PET masterbatch.

[0007] A further improvement of the present invention is that, in step S1, the PET substrate slices are vacuum dried at a temperature of 120–140°C for 4–6 hours.

[0008] A further improvement of the present invention is that, in step S1, the polymeric carbodiimide anti-hydrolysis agent, dispersant, anti-crosslinking agent, heat stabilizer, and antioxidant are vacuum dried at a temperature of 80–100°C for 2–3 hours.

[0009] A further improvement of the present invention is that, in step S2, the mixing temperature of the high-speed mixer is 60-80°C, the stirring speed is 800-1200 r / min, and the mixing time is 15-30 minutes.

[0010] A further improvement of the present invention is that, in step S4, the water temperature of the cooling water tank is 20-30°C.

[0011] A further improvement of the present invention is that, in step S5, the particle size of the initial masterbatch is 2-3 mm.

[0012] A further improvement of the present invention is that, in step S6, the temperature of the primary masterbatch during vacuum drying is 100-120°C.

[0013] A further improvement of the present invention is that the initial masterbatch is dried in vacuum for 2 to 3 hours.

[0014] Compared with existing technologies, the optimized process for preparing hydrolysis-resistant PET masterbatch provided by this invention achieves at least the following beneficial effects: The raw materials of this invention contain polymeric carbodiimide anti-hydrolysis agent and anti-crosslinking agent, which effectively inhibit the crosslinking reaction between the anti-hydrolysis agent and PET ester bonds during processing, avoiding problems such as film crystal points and spinning pore blockage. The added dispersant improves the dispersion uniformity of the anti-hydrolysis agent in the PET substrate, avoiding excessively high or low local concentrations caused by direct addition, and improving the consistency of the anti-hydrolysis effect. The heat stabilizer can inhibit the thermal degradation of PET during processing. The antioxidant can delay the oxidative aging of the material and improve color stability. The combination of low-temperature pre-dispersion and mild extrusion granulation process reduces the processing temperature and shear strength, reduces the thermal degradation of the PET substrate and the premature reaction of the anti-hydrolysis agent, stabilizes the intrinsic viscosity of the masterbatch, and improves the anti-hydrolysis efficiency. Attached Figure Description

[0015] Figure 1 This is a flowchart of an optimized process for preparing hydrolysis-resistant PET masterbatch according to the present invention. Detailed Implementation

[0016] Various exemplary embodiments of the present invention will now be described in detail. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0017] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0018] See Figure 1 An optimized process for preparing hydrolysis-resistant PET masterbatch includes the following steps: S1. Raw material pretreatment: Vacuum dry the PET substrate slices to control the moisture content ≤0.05% to avoid hydrolysis; Vacuum dry the polymeric carbodiimide anti-hydrolysis agent, dispersant, anti-crosslinking agent, heat stabilizer, and antioxidant separately to remove moisture and volatile impurities; The raw materials for PET substrate chips include the following components by weight: 70-85 parts PET substrate, 10-20 parts polymeric carbodiimide anti-hydrolysis agent, 2-5 parts dispersant, 1-3 parts anti-crosslinking agent, 0.5-2 parts heat stabilizer, and 0.3-1 parts antioxidant. The PET substrate is selected from PET chips with an intrinsic viscosity of 0.65-0.85 dL / g, using random copolymer PET or homopolymer PET to ensure compatibility between the masterbatch and the subsequent processed substrate. The polymeric carbodiimide anti-hydrolysis agent has a number average molecular weight of 5000-20000 g / mol and a carbodiimide group content of 8-12 mmol / g, selected from one or a combination of two of poly(1,3-phenylene carbodiimide) and poly(4,4'-methylenediphenylcarbodiimide) to avoid small molecule precipitation and ensure... The hydrolysis resistance is enhanced by the following: the dispersant is selected from one or more of ethylene acrylate copolymer (EAA), polyethylene glycol (PEG) with a molecular weight of 2000-6000 g / mol, and calcium stearate, which improves the uniformity of the hydrolysis resistance agent in the PET substrate; the anti-crosslinking agent is selected from monofunctional epoxy compounds, including glycidyl ether and epoxidized soybean oil, which inhibit the crosslinking reaction with PET ester bonds by selectively reacting with the active groups of polymeric carbodiimide; the heat stabilizer is selected from phosphite compounds, including tris(2,4-di-tert-butylphenyl) phosphite, which inhibits the thermal degradation of PET during processing; the antioxidant is selected from hindered phenolic antioxidants 1010 or 1076, which delay the oxidative aging of the material and improve color stability. S2. Low-temperature pre-dispersion: Weigh the dried raw materials according to the formula ratio and add them to a high-speed mixer to make the anti-hydrolysis agent and additives evenly adhere to the surface of the PET substrate to form a premix; during the mixing process, the temperature is controlled not to exceed 80°C by cooling with a jacket to avoid premature reaction; S3. Mild Extrusion Granulation: The premix is ​​added to a twin-screw extruder, and the extrusion process parameters are set as follows: screw speed: 100-150 r / min; barrel zone 1 temperature: 180-200℃, barrel zone 2 temperature: 230-250℃, barrel zone 3 temperature: 250-260℃, barrel zone 4 temperature: 255-265℃, die head temperature: 260-270℃; vacuum degree: -0.08--0.09 MPa, used to promptly remove volatiles; the premix is ​​melted and mixed in the twin-screw extruder, and then extruded into filaments through the die head; S4. The filaments are rapidly cooled and shaped in a cooling water tank to avoid secondary cross-linking; S5. Pelletize the raw masterbatch using a pelletizer; S6. Vacuum dry the primary masterbatch to remove surface moisture and obtain hydrolysis-resistant PET masterbatch.

[0019] In step S1, the PET substrate chips are vacuum dried at 120–140°C for 4–6 hours; in step S1, the polymeric carbodiimide anti-hydrolysis agent, dispersant, anti-crosslinking agent, heat stabilizer, and antioxidant are vacuum dried at 80–100°C for 2–3 hours; in step S2, the mixing temperature of the high-speed mixer is 60–80°C, the stirring speed is 800–1200 r / min, and the mixing time is 15–30 minutes.

[0020] In step S4, the water temperature in the cooling water tank is 20-30℃; in step S5, the particle size of the primary masterbatch is 2-3mm; in step S6, the temperature of the primary masterbatch during vacuum drying is 100-120℃; and the vacuum drying time of the primary masterbatch is 2-3 hours.

[0021] Example 1 S11. Formulation composition: By weight, 78 parts PET substrate; 15 parts polymeric carbodiimide hydrolysate, selected from poly(4,4'-methylenediphenylcarbodiimide), with a number average molecular weight of 10,000 g / mol and a group content of 10 mmol / g; 3 parts dispersant, selected from ethylene acrylate copolymer (EAA); 2 parts anti-crosslinking agent, selected from glycidyl ether; 1 part heat stabilizer, selected from tris(2,4-di-tert-butylphenyl) phosphite; 0.5 parts antioxidant, selected from hindered phenolic antioxidant 1010.

[0022] S12. PET chips were vacuum dried at 130℃ for 5 hours, and the remaining raw materials were vacuum dried at 90℃ for 2.5 hours. Low-temperature pre-dispersion was carried out at 60℃, 1000r / min, and mixed for 20 minutes to obtain the premix.

[0023] S13. Mild extrusion: Twin screw speed 120r / min, barrel zone 1 temperature 190℃, zone 2 temperature 240℃, zone 3 temperature 255℃, zone 4 temperature 260℃, die head temperature 265℃, vacuum degree -0.085MPa.

[0024] S14. Cool to 25°C and pelletize, then vacuum dry at 110°C for 2.5 hours to obtain hydrolysis-resistant PET masterbatch.

[0025] Example 2 S21. Formulation composition: By weight, 75 parts PET substrate; 15 parts polymeric carbodiimide hydrolysant, selected from poly(1,3-phenylene carbodiimide), with a number average molecular weight of 15000 g / mol and a group content of 9 mmol / g; 4 parts dispersant, selected from polyethylene glycol (PEG); 1.5 parts anti-crosslinking agent, selected from epoxidized soybean oil; 1 part heat stabilizer, selected from tris(2,4-di-tert-butylphenyl) phosphite; 0.5 parts antioxidant, selected from hindered phenolic antioxidant 1076.

[0026] S22. PET chips were vacuum dried at 135℃ for 4.5 hours, and the remaining raw materials were vacuum dried at 95℃ for 2 hours. Low-temperature pre-dispersion was carried out at 70℃, 1100r / min, and mixed for 25 minutes to obtain the premix.

[0027] S23. Mild extrusion: Twin screw speed 130r / min, barrel temperature zone 1 195℃, zone 2 245℃, zone 3 258℃, zone 4 262℃, die head temperature 268℃, vacuum degree -0.09MPa.

[0028] S24. Cool to 28℃ and pelletize, then vacuum dry at 115℃ for 2 hours to obtain hydrolysis-resistant PET masterbatch.

[0029] In summary, this invention provides an optimized process for preparing hydrolysis-resistant PET masterbatch. The raw materials contain a polymeric carbodiimide hydrolysis-resistant agent and an anti-crosslinking agent, effectively inhibiting the crosslinking reaction between the hydrolysis-resistant agent and PET ester bonds during processing, thus avoiding problems such as film crystal points and spinning pore blockage. The added dispersant improves the dispersion uniformity of the hydrolysis-resistant agent in the PET substrate, avoiding excessively high or low local concentrations caused by direct addition, and improving the consistency of the hydrolysis-resistant effect. The heat stabilizer inhibits the thermal degradation of PET during processing; the antioxidant delays the oxidative aging of the material and improves color stability; the combined low-temperature pre-dispersion and mild extrusion granulation process reduces the processing temperature and shear strength, decreasing the thermal degradation of the PET substrate and the premature reaction of the hydrolysis-resistant agent, resulting in stable masterbatch intrinsic viscosity and thus improving hydrolysis resistance efficiency.

[0030] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. An optimized process for preparing hydrolysis-resistant PET masterbatch, characterized in that, Includes the following steps: S1. Raw material pretreatment: Vacuum dry the PET substrate slices to control the moisture content ≤0.05% to avoid hydrolysis; Vacuum dry the polymeric carbodiimide anti-hydrolysis agent, dispersant, anti-crosslinking agent, heat stabilizer, and antioxidant separately to remove moisture and volatile impurities; The raw materials for PET substrate chips include the following components by weight: 70-85 parts PET substrate, 10-20 parts polymeric carbodiimide anti-hydrolysis agent, 2-5 parts dispersant, 1-3 parts anti-crosslinking agent, 0.5-2 parts heat stabilizer, and 0.3-1 parts antioxidant. The PET substrate is selected from PET chips with an intrinsic viscosity of 0.65-0.85 dL / g, using random copolymer PET or homopolymer PET to ensure compatibility between the masterbatch and the subsequent processed substrate. The polymeric carbodiimide anti-hydrolysis agent has a number average molecular weight of 5000-20000 g / mol and a carbodiimide group content of 8-12 mmol / g, selected from one or a combination of two of poly(1,3-phenylene carbodiimide) and poly(4,4'-methylenediphenylcarbodiimide) to avoid small molecule precipitation and ensure... The hydrolysis resistance is enhanced by the following: the dispersant is selected from one or more of ethylene acrylate copolymer (EAA), polyethylene glycol (PEG) with a molecular weight of 2000-6000 g / mol, and calcium stearate, which improves the uniformity of the hydrolysis resistance agent in the PET substrate; the anti-crosslinking agent is selected from monofunctional epoxy compounds, including glycidyl ether and epoxidized soybean oil, which inhibit the crosslinking reaction with PET ester bonds by selectively reacting with the active groups of polymeric carbodiimide; the heat stabilizer is selected from phosphite compounds, including tris(2,4-di-tert-butylphenyl) phosphite, which inhibits the thermal degradation of PET during processing; the antioxidant is selected from hindered phenolic antioxidants 1010 or 1076, which delay the oxidative aging of the material and improve color stability. S2. Low-temperature pre-dispersion: Weigh the dried raw materials according to the formula ratio and add them to a high-speed mixer to make the anti-hydrolysis agent and additives evenly adhere to the surface of the PET substrate to form a premix; during the mixing process, the temperature is controlled not to exceed 80°C by cooling with a jacket to avoid premature reaction; S3. Mild extrusion granulation: Add the premixed material to the twin-screw extruder, set the extrusion process parameters, screw speed: 100~150r / min; barrel zone 1 temperature: 180~200℃, barrel zone 2 temperature: 230~250℃, barrel zone 3 temperature: 250~260℃, barrel zone 4 temperature: 255~265℃, die head temperature: 260~270℃; Vacuum degree: -0.08~-0.09MPa, used to remove volatiles in a timely manner; the premixed material is melted in a twin-screw extruder, mixed, and then extruded into filaments through a die; S4. The filaments are rapidly cooled and shaped in a cooling water tank to avoid secondary cross-linking; S5. Pelletize the raw masterbatch using a pelletizer; S6. Vacuum dry the primary masterbatch to remove surface moisture and obtain hydrolysis-resistant PET masterbatch.

2. The optimized process for preparing hydrolysis-resistant PET masterbatch according to claim 1, characterized in that, In step S1, the PET substrate slices are vacuum dried at 120-140°C for 4-6 hours.

3. The optimized process for preparing hydrolysis-resistant PET masterbatch according to claim 1, characterized in that, In step S1, the polymeric carbodiimide anti-hydrolysis agent, dispersant, anti-crosslinking agent, heat stabilizer, and antioxidant are vacuum dried at 80-100°C for 2-3 hours.

4. The optimized process for preparing hydrolysis-resistant PET masterbatch according to claim 1, characterized in that, In step S2, the mixing temperature of the high-speed mixer is 60-80℃, the stirring speed is 800-1200 r / min, and the mixing time is 15-30 minutes.

5. The optimized process for preparing hydrolysis-resistant PET masterbatch according to claim 1, characterized in that, In step S4, the water temperature of the cooling water tank is 20-30℃.

6. The optimized process for preparing hydrolysis-resistant PET masterbatch according to claim 1, characterized in that, In step S5, the particle size of the initial masterbatch is 2-3 mm.

7. The optimized process for preparing hydrolysis-resistant PET masterbatch according to claim 1, characterized in that, In step S6, the temperature of the primary masterbatch during vacuum drying is 100-120°C.

8. The optimized process for preparing hydrolysis-resistant PET masterbatch according to claim 8, characterized in that, The initial masterbatch is vacuum dried for 2 to 3 hours.

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