Polyester matte master batch and preparation method and application thereof

Abstract

The present application relates to the technical field of high polymer material, and discloses a polyester matte master batch as well as a preparation method and application thereof.The polyester matte master batch provided by the present application comprises, in terms of weight fraction, polyester ethylene terephthalate resin 70-95 parts, silane-modified silicon dioxide 1-20 parts, acrylic ester core-shell microspheres 1-5 parts, melt strength modifier 1-5 parts, dispersant 0.1-2 parts, antioxidant 0.1-2 parts, and anti-hydrolysis agent 0.5-2 parts; and the silane-modified silicon dioxide has a median particle size of 2.5-4 mu m.The present application successfully realizes the breakthrough in the comprehensive performance of polyester film, i.e., haze ≥ 90.7%, haze uniformity ≤ 1.6%, low film breaking rate, and fewer crystal points, thereby effectively reducing the production cost while ensuring the excellent performance of the matte film and realizing stable production.

Description

Technical Field

[0001] This invention relates to the field of functional polymer materials technology, specifically to a polyester matte masterbatch, its preparation method, and its application. Background Technology

[0002] Biaxially oriented polyester (BOPET) film is widely used in packaging materials, decorative materials, and optical displays due to its excellent mechanical properties, optical properties, dimensional stability, and heat resistance. Among them, matte BOPET film, with its low gloss and high haze characteristics, is in increasing demand in decorative materials, backlight modules, and optical films.

[0003] Currently, adding silica matting agents to polyester materials is the most common method to achieve a matte finish. To achieve a high matte effect, the content of the matting agent in the matte masterbatch needs to be sufficiently high, and the amount added to this masterbatch also needs to be maintained at a high level in actual BOPET film production to ensure that the haze on the film surface meets the requirements. However, this high-content addition strategy brings many processing and quality problems. Although there are several reports on polyester matte masterbatches in existing technologies, the following technical shortcomings still exist: The production of BOPET film involves longitudinal and transverse stretching processes, and the melt needs to possess sufficient tensile strength under high-speed stretching conditions. When silica is added in high amounts, the inorganic powder particles disrupt the physical entanglement network between polyethylene terephthalate (PET) molecular chains, making the melt prone to localized necking or even breakage during stretching. Meanwhile, in actual BOPET film production, this high-content masterbatch needs to be diluted and mixed with the base PET resin before use. However, the significant viscosity difference between the masterbatch and the base resin leads to inconsistent melt flow behavior in the die channel and stretching section—the low-viscosity masterbatch phase and the high-viscosity base phase struggle to achieve uniform stress transfer and synergistic deformation in the blend system, resulting in localized melt flow rate differences. This ultimately manifests as uneven film haze distribution and frequent film breakage and production interruptions.

[0004] Therefore, how to prepare polyester films that have both high haze and low fluctuation and stable production is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This invention provides a polyester matte masterbatch to solve the problems of low and fluctuating haze and poor processability of existing polyester films.

[0006] In a first aspect, the present invention provides a polyester matte masterbatch, wherein, by weight, the raw materials of the polyester matte masterbatch include: 70-95 parts of polyethylene terephthalate resin, 1-20 parts of silane-modified silica, 1-5 parts of acrylate core-shell microspheres, 1-5 parts of melt strength modifier, 0.1-2 parts of dispersant, 0.1-2 parts of antioxidant, and 0.5-2 parts of anti-hydrolysis agent; The median particle size of the silane-modified silica is 2.5 μm-4 μm.

[0007] In one optional embodiment, the polyethylene terephthalate resin has an intrinsic viscosity of 0.65 dL / g-0.70 dL / g and a melting point of 240℃-260℃.

[0008] In one optional embodiment, the silane-modified silica has a pore volume of 0.8 mL / g-1.2 mL / g and a maximum particle size of 5 μm-12 μm.

[0009] In one optional embodiment, the acrylate core-shell microspheres have a particle size of 100nm-500nm and a thermal decomposition temperature of 260℃-300℃.

[0010] In one optional embodiment, the melt strength modifier has a melt flow rate of 2 g / 10 min to 5 g / 10 min at 300 °C and 1.2 kg.

[0011] In one optional embodiment, the method for preparing the acrylate core-shell microspheres includes: (1) subjecting a first core layer monomer, a first emulsifier, a first initiator, and a first crosslinking agent to a first reaction to obtain a seed emulsion; (2) After pre-emulsifying the second core layer monomer, the second emulsifier, the second initiator and the second crosslinking agent, they are added dropwise to the seed emulsion. After the second reaction, the core layer emulsion is obtained. (3) After pre-emulsifying the shell monomer, the third emulsifier, the third initiator and the third crosslinking agent, the mixture is added dropwise to the core emulsion. After the third reaction, the acrylate core-shell microspheres are obtained. The first core layer monomer, the second core layer monomer, and the shell layer monomer all include butyl acrylate and methyl methacrylate; In steps (1) and (2), the mass ratio of butyl acrylate to methyl methacrylate is independently 8.5-9.5:1; In step (3), the mass ratio of butyl acrylate to methyl methacrylate is 1:8.5-9.5.

[0012] In an optional implementation, in step (3), the mass of the shell monomer is 35%-45% of the total mass of the first core monomer, the second core monomer, and the shell monomer.

[0013] In one alternative embodiment, the mass ratio of the first core layer monomer to the second core layer monomer is 1:18-20.

[0014] In one optional embodiment, the mass ratio of the first core layer monomer, the first emulsifier, the first initiator, and the first crosslinking agent is 100:8-12:1-1.4:1.5-2.5.

[0015] In one optional embodiment, the mass ratio of the second core layer monomer, the second emulsifier, the second initiator, and the second crosslinking agent is 100:0.8-2:0.3-0.6:1.5-2.5.

[0016] In one optional embodiment, the mass ratio of the shell monomer, the third emulsifier, the third initiator, and the third crosslinking agent is 100:1-2:0.3-0.6:2.5-3.5.

[0017] In one optional embodiment, the method for preparing the silane-modified silica includes: heat-treating silica and a silane coupling agent to obtain the silica.

[0018] In one optional embodiment, the silane coupling agent comprises at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0019] In one optional embodiment, the mass of the silane coupling agent is 1wt%-3wt% of the mass of the silicon dioxide.

[0020] In one optional embodiment, the heat treatment is performed at a temperature of 70°C-90°C for 1.5h-2.5h, and at a pH of 2.5-3.5.

[0021] In one alternative embodiment, the melt strength modifier comprises branched polycarbonate.

[0022] In one alternative embodiment, the anti-hydrolysis agent includes at least one of polymerized carbodiimide and monomeric carbodiimide.

[0023] In one alternative embodiment, the dispersant comprises at least one of stearic acid, polyethylene wax, oxidized polyethylene wax, and ethylene bis-stearamide.

[0024] In one optional embodiment, the antioxidant comprises at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris[2,4-di-tert-butylphenyl] phosphite, bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite, and bis(octadecyl)thiodipropionate.

[0025] In a second aspect, the present invention provides a method for preparing the polyester matte masterbatch described in the first aspect, comprising the following steps: Polyethylene terephthalate resin is fed into a twin-screw extruder through the main feed port. Silane-modified silica, acrylate core-shell microspheres, melt strength modifier, dispersant, antioxidant, and anti-hydrolysis agent are added into the twin-screw extruder through the side feed port. After mixing with polyethylene terephthalate resin, the mixture is extruded to obtain the polyester matte masterbatch.

[0026] In one optional embodiment, the melting temperature of the polyethylene terephthalate resin is 240°C-280°C.

[0027] In one alternative embodiment, the mixing temperature is 200°C-260°C.

[0028] In one optional embodiment, the vacuum degree of the extrusion is -0.06MPa to -0.01MPa, and the material residence time is <150s.

[0029] In an alternative embodiment, the molten material is further filtered using a 200-800 mesh filter before extrusion.

[0030] Thirdly, the present invention provides an application of the polyester matte masterbatch prepared by the preparation method described in the second aspect in polyester films.

[0031] The technical solution of this invention has the following advantages: 1. The polyester matte masterbatch provided by this invention, by weight, comprises the following raw materials: 70-95 parts polyethylene terephthalate resin, 1-20 parts silane-modified silica, 1-5 parts acrylate core-shell microspheres, 1-5 parts melt strength modifier, 0.1-2 parts dispersant, 0.1-2 parts antioxidant, and 0.5-2 parts anti-hydrolysis agent; the median particle size of the silane-modified silica is 2.5μm-4μm. This invention successfully achieves a breakthrough in the comprehensive performance of polyester film with haze ≥90.7%, haze uniformity ≤1.6%, low film breakage rate, and fewer crystal points. While ensuring the excellent performance of matte film, it effectively reduces production costs and achieves stable production. Detailed Implementation

[0032] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0033] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0034] To address the aforementioned problems, in a first aspect, the present invention provides a polyester matte masterbatch, wherein, by weight, the raw materials of the polyester matte masterbatch include: 70-95 parts of polyethylene terephthalate resin, 1-20 parts of silane-modified silica, 1-5 parts of acrylate core-shell microspheres, 1-5 parts of melt strength modifier, 0.1-2 parts of dispersant, 0.1-2 parts of antioxidant, and 0.5-2 parts of anti-hydrolysis agent; The median particle size of the silane-modified silica is 2.5 μm-4 μm.

[0035] In this invention, after the surface of silane-modified silica is chemically modified by a silane coupling agent, the hydrolyzable group at one end of the coupling agent forms a Si-O-Si chemical bond with the hydroxyl group on the surface of silica, and the organic functional group at the other end gives the particle surface good compatibility with the PET matrix, improves the dispersibility of inorganic powder in polyester, and at the same time changes the silica from a hydrophilic structure to a hydrophobic structure.

[0036] Meanwhile, the melt strength modifier and PET do not separate when blended, and the thickening effect can be maintained stably. Its high viscosity characteristics give the masterbatch a higher melt viscosity, reducing the viscosity difference between the masterbatch and the matrix resin. This allows for more uniform stress transfer and synergistic deformation of the two-phase melt in the die flow channel and stretching section, thereby reducing film thickness fluctuations and the risk of film breakage. The dual effects of physical entanglement and viscosity matching ensure the processing stability of high-silica masterbatch during high-speed stretching of BOPET.

[0037] The -N=C=N- group of the anti-hydrolysis agent can react with the terminal carboxyl groups generated by PET hydrolysis to form a stable acylurea structure, breaking the hydrolysis autocatalytic chain and effectively inhibiting the hydrolytic degradation of polyester during high-temperature processing, thus achieving melt viscosity stability. The dispersant promotes uniform dispersion of all components, and the antioxidant prevents thermal oxidative degradation of the masterbatch during high-temperature processing. The synergistic effect of these components enables the masterbatch to achieve stable dispersion of high silica content (1-20 parts) while simultaneously achieving a film haze exceeding 90%, effectively reducing production costs while maintaining high haze, high uniformity, and high viscosity stability.

[0038] In one optional embodiment, the raw materials of the polyester matte masterbatch, by weight, include: 73-85 parts of polyethylene terephthalate resin, 10-20 parts of silane-modified silica, 1-3 parts of acrylate core-shell microspheres, 1-3 parts of melt strength modifier, 0.4-1 parts of dispersant, 0.1-1 parts of antioxidant, and 0.5-1 parts of anti-hydrolysis agent.

[0039] In one optional embodiment, the intrinsic viscosity of the polyethylene terephthalate resin is 0.65 dL / g-0.70 dL / g, and the melting point is 240℃-260℃. As an example, the intrinsic viscosity of the polyethylene terephthalate resin can be 0.65 dL / g, 0.66 dL / g, 0.67 dL / g, 0.68 dL / g, 0.69 dL / g, 0.70 dL / g, or any range thereof; the melting point can be 240℃, 242℃, 244℃, 246℃, 248℃, 250℃, 252℃, 254℃, 256℃, 258℃, 260℃, or any range thereof.

[0040] In one optional embodiment, the silane-modified silica has a pore volume of 0.8 mL / g-1.2 mL / g and a maximum particle size of 5 μm-12 μm. As an example, the pore volume of the silane-modified silica can be 0.8 mL / g, 0.85 mL / g, 0.9 mL / g, 0.95 mL / g, 1 mL / g, 1.05 mL / g, 1.1 mL / g, 1.15 mL / g, 1.2 mL / g, or any range of the above values; the maximum particle size can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, or any range of the above values.

[0041] Furthermore, this invention achieves this by precisely controlling the pore volume of the silica to be 0.8 mL / g-1.2 mL / g and the median particle size D. 50 The particle size ranges from 2.5μm to 4μm, with a maximum particle size of 5μm to 12μm, to achieve the best matte finish and processing stability, while eliminating oversized particles and avoiding the risk of film scratches and screen clogging.

[0042] In one optional embodiment, the acrylate core-shell microspheres have a particle size of 100nm-500nm and a thermal decomposition temperature of 260℃-300℃. As an example, the particle size of the acrylate core-shell microspheres can be 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, etc., or any range of the above values; the thermal decomposition temperature can be 260℃, 265℃, 270℃, 275℃, 280℃, 285℃, 290℃, 295℃, 300℃, etc., or any range of the above values.

[0043] In one optional embodiment, the melt flow rate of the melt strength modifier at 300°C and 1.2 kg is 2 g / 10 min to 5 g / 10 min. As an example, the melt flow rate of the melt strength modifier at 300°C and 1.2 kg can be 2 g / 10 min, 2.5 g / 10 min, 3 g / 10 min, 3.5 g / 10 min, 4 g / 10 min, 4.5 g / 10 min, 5 g / 10 min, etc., or a range of any of the above values.

[0044] It should be noted that branched polycarbonate, as a melt strength modifier, has a melt flow rate (300℃ / 1.2kg) of 2g / 10min-5g / 10min. The extremely low flow rate indicates that the powder has extremely high melt viscosity and ultra-high molecular weight. The molecular chains of this powder have a large number of branched structures, which can form a denser physical entanglement network in PET melt than linear molecular chains. During the high-speed stretching process of BOPET, it effectively resists the relative slippage of molecular chains and compensates for the melt strength loss due to the high content of silica filler.

[0045] In one optional embodiment, the method for preparing the acrylate core-shell microspheres includes: (1) subjecting a first core layer monomer, a first emulsifier, a first initiator, and a first crosslinking agent to a first reaction to obtain a seed emulsion; (2) After pre-emulsifying the second core layer monomer, the second emulsifier, the second initiator and the second crosslinking agent, they are added dropwise to the seed emulsion. After the second reaction, the core layer emulsion is obtained. (3) After pre-emulsifying the shell monomer, the third emulsifier, the third initiator and the third crosslinking agent, the mixture is added dropwise to the core emulsion. After the third reaction, the acrylate core-shell microspheres are obtained. The first core layer monomer, the second core layer monomer, and the shell layer monomer all include butyl acrylate and methyl methacrylate; In steps (1) and (2), the mass ratio of butyl acrylate to methyl methacrylate is independently 8.5-9.5:1; In step (3), the mass ratio of butyl acrylate to methyl methacrylate is 1:8.5-9.5.

[0046] As an example, in steps (1) and (2), the mass ratio of butyl acrylate to methyl methacrylate can each independently be 8.5:1, 8.6:1, 8.7:1, 8.8:1, 8.9:1, 9:1, 9.1:1, 9.2:1, 9.3:1, 9.4:1, 9.5:1, etc., or a range of any of the above values.

[0047] As an example, in step (3), the mass ratio of butyl acrylate to methyl methacrylate can be 1:8.5, 1:8.6, 1:8.7, 1:8.8, 1:8.9, 1:9, 1:9.1, 1:9.2, 1:9.3, 1:9.4, 1:9.5, or a range of any of the above values.

[0048] It should be noted that the acrylate core-shell microspheres of the present invention have a unique double-layer structure. The core is a cross-linked acrylate copolymer, which can absorb and disperse stress during the stretching process of BOPET and help reduce the risk of film breakage. The hard shell is a cross-linked methacrylate copolymer. By introducing a cross-linked structure, the thermal decomposition temperature of the microspheres can reach above 260°C, which can meet the morphological stability requirements of BOPET film at a processing temperature of 240°C-280°C, ensuring that the microspheres do not deform or collapse during processing.

[0049] In one optional implementation, in step (3), the mass of the shell monomer is 35%-45% of the total mass of the first core monomer, the second core monomer, and the shell monomer. As an example, in step (3), the mass of the shell monomer can be 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, etc., of the total mass of the first core monomer, the second core monomer, and the shell monomer, or a range of any of the above values.

[0050] In one alternative embodiment, the mass ratio of the first core layer monomer to the second core layer monomer is 1:18-20. As an example, the mass ratio of the first core layer monomer to the second core layer monomer can be 1:18, 1:18.2, 1:18.4, 1:18.6, 1:18.8, 1:19, 1:19.2, 1:19.4, 1:19.6, 1:19.8, 1:20, or a range of any of the above values.

[0051] In one optional embodiment, the mass ratio of the first core layer monomer, the first emulsifier, the first initiator, and the first crosslinking agent is 100:8-12:1-1.4:1.5-2.5. As an example, the mass ratio of the first core layer monomer, the first emulsifier, the first initiator, and the first crosslinking agent can be 100:10:1:2.5, 100:10:1.4:1.5, 100:12:1:2.5, 100:12:1.4:1.5, 100:8:1:2.5, 100:8:1.4:1.5, or any range of the above values.

[0052] In one optional embodiment, the mass ratio of the second core layer monomer, the second emulsifier, the second initiator, and the second crosslinking agent is 100:1-2:0.3-0.6:1.5-2.5. As an example, the mass ratio of the second core layer monomer, the second emulsifier, the second initiator, and the second crosslinking agent can be 100:1.5:0.3:2.5, 100:1.5:0.6:1.5, 100:1:0.3:2.5, 100:1:0.6:1.5, 100:2:0.3:2.5, 100:2:0.6:1.5, or a range of any of the above values.

[0053] In one optional embodiment, the mass ratio of the shell monomer, the third emulsifier, the third initiator, and the third crosslinking agent is 100:1-2:0.3-0.6:2.5-3.5. As an example, the mass ratio of the shell monomer, the third emulsifier, the third initiator, and the third crosslinking agent can be 100:1.5:0.3:2.5, 100:1.5:0.6:3.5, 100:1:0.3:2.5, 100:1:0.6:3.5, 100:2:0.3:2.5, 100:2:0.6:3.5, etc., or a range of any of the above values.

[0054] Furthermore, the first emulsifier, the second emulsifier, and the third emulsifier are each independently selected from at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and alkylphenol polyoxyethylene ether; preferably sodium dodecyl sulfate.

[0055] Furthermore, the first initiator, the second initiator, and the third initiator are each independently selected from at least one of ammonium persulfate, potassium persulfate, and sodium persulfate; preferably potassium persulfate.

[0056] Furthermore, the first crosslinking agent, the second crosslinking agent, and the third crosslinking agent are each independently selected from at least one of ethylene glycol dimethacrylate, N,N'-methylenebisacrylamide, and polyethylene glycol dimethacrylate; preferably ethylene glycol dimethacrylate.

[0057] Furthermore, the temperature of the first reaction is 75℃-85℃, and the time is 1h-3h.

[0058] Further, in step (2), the dropping rate is 0.3 g / min-0.4 g / min, the temperature of the second reaction is 75℃-85℃, and the time is 1h-3h.

[0059] Furthermore, in step (2), the pre-emulsification temperature is 25℃-40℃ and the time is 0.5h-1h.

[0060] Furthermore, in step (3), the dropping rate is 0.1 g / min-0.3 g / min, the temperature of the third reaction is 75℃-85℃, and the time is 1h-3h.

[0061] Furthermore, in step (3), the pre-emulsification temperature is 25℃-40℃ and the time is 0.5h-1h.

[0062] In one optional embodiment, the method for preparing the silane-modified silica includes: heat-treating silica and a silane coupling agent to obtain the silica.

[0063] In one optional embodiment, the silane coupling agent comprises at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0064] In one optional embodiment, the mass of the silane coupling agent is 1wt%-3wt% of the mass of the silica. As an example, the mass of the silane coupling agent can be 1wt%, 1.2wt%, 1.4wt%, 1.6wt%, 1.8wt%, 2wt%, 2.2wt%, 2.4wt%, 2.6wt%, 2.8wt%, 3wt%, or any range of the above values, all of which are part of the mass of the silica.

[0065] In one optional embodiment, the heat treatment temperature is 70℃-90℃, the time is 1.5h-2.5h, and the pH is 2.5-3.5. As an example, the heat treatment temperature can be 70℃, 72℃, 74℃, 76℃, 78℃, 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, etc., or any range of the above values; the time can be 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, etc., or any range of the above values; the pH can be 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, etc., or any range of the above values.

[0066] In one alternative embodiment, the melt strength modifier comprises branched polycarbonate.

[0067] In one alternative embodiment, the anti-hydrolysis agent includes at least one of polymerized carbodiimide and monomeric carbodiimide.

[0068] In one alternative embodiment, the dispersant comprises at least one of stearic acid, polyethylene wax, oxidized polyethylene wax, and ethylene bis-stearamide.

[0069] In an optional embodiment, the antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), tris[2,4-di-tert-butylphenyl] phosphite (antioxidant 168), pentaerythritol diphosphite bis(2,4-di-tert-butylphenol) (antioxidant 626), and dioctadecyl thiodipropionate (antioxidant DSTP).

[0070] In a second aspect, the present invention provides a method for preparing the polyester matte masterbatch described in the first aspect, comprising the following steps: Polyethylene terephthalate resin is fed into a twin-screw extruder through the main feed port. Silane-modified silica, acrylate core-shell microspheres, melt strength modifier, dispersant, antioxidant, and anti-hydrolysis agent are added into the twin-screw extruder through the side feed port. After mixing with polyethylene terephthalate resin, the mixture is extruded to obtain the polyester matte masterbatch.

[0071] In one optional embodiment, the melting temperature of the polyethylene terephthalate resin is 240°C-280°C. As an example, the melting temperature of the polyethylene terephthalate resin can be 240°C, 245°C, 250°C, 255°C, 260°C, 265°C, 270°C, 275°C, 280°C, or a range of any of the above values.

[0072] In one optional embodiment, the mixing temperature is 200℃-260℃. As an example, the mixing temperature can be 200℃, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, 235℃, 240℃, 245℃, 250℃, 255℃, 260℃, or a range of any of the above values.

[0073] In one optional embodiment, the extrusion vacuum is -0.06 MPa to -0.01 MPa, and the material residence time is <150 s. As an example, the extrusion vacuum can be -0.06 MPa, -0.05 MPa, -0.04 MPa, -0.03 MPa, -0.02 MPa, -0.01 MPa, or any range of these values; the material residence time can be 100 s, 110 s, 120 s, 130 s, 140 s, 149 s, or any range of these values.

[0074] In an alternative embodiment, the molten material is further filtered using a 200-800 mesh filter before extrusion.

[0075] Thirdly, the present invention provides an application of the polyester matte masterbatch prepared by the preparation method described in the second aspect in polyester films.

[0076] It should be noted that the residence time of the material in the twin-screw extruder directly affects its heating degree. If the residence time is too short, the silane-modified silica will not disperse sufficiently; if the residence time is too long, the polyester is prone to thermal oxidative degradation at high temperatures, leading to a decrease in intrinsic viscosity and deterioration of mechanical properties. Therefore, controlling the material residence time can ensure sufficient dispersion while minimizing the material's residence time in the high-temperature range, thereby reducing the thermal oxidative degradation of the polyester. Controlling the vacuum level to -0.06 MPa to -0.01 MPa can remove residual moisture and small-molecule volatiles generated during melt blending.

[0077] Before extrusion, the process also includes filtering the molten material with a 200-800 mesh screen to remove any potentially large particles or foreign objects, further ensuring the purity of the masterbatch and the filtration stability of downstream processing.

[0078] In this invention, polyethylene terephthalate resin was purchased from Yizheng Chemical Fiber, model FG600; branched polycarbonate was purchased from Tianjin Wanhua, model 2030B, with a melt flow rate of 3 g / 10 min at 300℃ and 1.2 kg; polymerized carbodiimide was purchased from Suzhou Keshengtong New Material Technology Co., Ltd., model Bio-SAHTM 372N; silica with a median particle size of 3 μm was purchased from Evonik Degussa, Germany, model HK400; silica with a median particle size of 2.5 μm was purchased from Evonik Degussa, Germany, model HK460; silica with a median particle size of 4 μm was purchased from Evonik Degussa, Germany, model HK125; and silica with a median particle size of 6 μm was purchased from Qingyuan Xinhui Chemical Co., Ltd.

[0079] Preparation Example 1 This preparation example provides a method for preparing silane-modified silica, comprising the following steps: 100 g of silica (median particle size 3 μm) was dispersed in 1000 mL of anhydrous ethanol, and then 1 g of γ-methacryloyloxypropyltrimethoxysilane (KH-570) was added. The pH was adjusted to 3 with 0.1 mol / L hydrochloric acid, and the mixture was stirred at 80 °C for 2 h. After the reaction was completed, the silica was centrifuged, washed, and dried to obtain silane-modified silica. The pore volume of the silane-modified silica was tested to be 0.85 mL / g, and the median particle size D was... 50 3μm, maximum particle size D 100 It is 9.5μm.

[0080] Preparation Example 2 This preparation example provides a method for preparing silane-modified silica, which is basically the same as the steps in Preparation Example 1, except that the median particle size of the silica is 2.5 μm. Testing showed that the prepared silane-modified silica has a pore volume of 0.94 mL / g and a median particle size D... 50 The particle size is 2.51 μm, and the maximum particle size D is... 100 It is 7.87 μm.

[0081] Preparation Example 3 This preparation example provides a method for preparing silane-modified silica, which is basically the same as the steps in Preparation Example 1, except that the median particle size of the silica is 4 μm. Testing showed that the prepared silane-modified silica had a pore volume of 0.95 mL / g and a median particle size D... 50 4μm, maximum particle size D 100 It is 11.1 μm.

[0082] Preparation Example 4 This preparation example provides a method for preparing silane-modified silica, which is basically the same as the steps in Preparation Example 1, except that the median particle size of the silica is 6 μm. Testing showed that the prepared silane-modified silica had a pore volume of 0.9 mL / g and a median particle size D... 50 With a particle size of 6μm and a maximum particle size D 100 It is 20.5μm.

[0083] Preparation Example 5 This preparation example provides a method for preparing acrylate core-shell microspheres, including the following steps: (1) Preparation of seed emulsion: 120g deionized water, 0.3g sodium dodecyl sulfate, 3g core layer monomer (2.7g butyl acrylate, 0.3g methyl methacrylate), 0.06g ethylene glycol dimethacrylate and 0.04g potassium persulfate were added to the reactor and the mixture was heated to 80℃ and reacted for 2h under nitrogen protection to prepare seed emulsion; (2) Preparation of cross-linked acrylate core emulsion: 57g core monomer (51.3g butyl acrylate, 5.7g methyl methacrylate), 1.14g ethylene glycol dimethacrylate, 0.5g sodium dodecyl sulfate, 0.2g potassium persulfate and 80g deionized water were pre-emulsified at 25℃ for 0.5h, and then added dropwise to the seed emulsion at a dropping rate of 0.38g / min. After the addition was completed, the mixture was kept at 80℃ for 1h to obtain the core emulsion. (3) High heat-resistant hard shell polymerization: 40g shell monomer (4g butyl acrylate, 36g methyl methacrylate), 1.2g ethylene glycol dimethacrylate, 0.5g sodium dodecyl sulfate, 0.2g potassium persulfate and 60g deionized water were pre-emulsified at 25℃ for 0.5h, and then added dropwise to the core emulsion in step (2) at 80℃ at a dropping rate of 0.2g / min. After the addition was completed, the mixture was kept at 80℃ for 1h. After demulsification, washing and drying, acrylate core-shell microspheres with a particle size of 500nm and a thermal decomposition temperature of 265℃ were obtained.

[0084] Example 1 This embodiment provides a method for preparing polyester matte masterbatch, including the following steps: (1) PET resin (intrinsic viscosity of 0.672 dL / g, melting point of 257℃) was dried in a high-speed mixer at 140℃ for 5h to obtain PET resin with a water content of 0.12%; silane-modified silica prepared in Preparation Example 1, acrylate core-shell microspheres prepared in Preparation Example 5, branched polycarbonate, polymerized carbodiimide, polyethylene wax, antioxidant 1010 and antioxidant 168 were dried at 110℃ for 5h to reduce the water content to below 1%; (2) 84.7 parts of dried PET resin were fed into a twin-screw extruder from the main feed port and heated to 270°C for melt shearing; 10 parts of dried silane-modified silica, 3 parts of acrylate core-shell microspheres, 1 part of branched polycarbonate, 0.5 parts of polymerized carbodiimide, 0.4 parts of ethylene bis-stearamide, 0.2 parts of antioxidant 1010 and 0.2 parts of antioxidant 168 were mixed and fed into the twin-screw extruder from the side feeder and melt-blended with PET resin at 250°C. The melted material was filtered through a 400-mesh filter and then extruded. The vacuum degree of the extrusion was -0.04MPa and the material residence time was 130s. After underwater pelleting (water temperature 35°C), centrifugal drying, vibrating sieve, and hot air drying to a moisture content ≤0.15%, polyester matte masterbatch was prepared.

[0085] Example 2 This embodiment provides a method for preparing a polyester matte masterbatch, which is basically the same as the steps in Example 1, except that the PET resin is 79.3 parts, the silane-modified silica is 15 parts, the acrylate core-shell microspheres are 2 parts, the branched polycarbonate is 2 parts, and the ethylene bis-stearamide is 0.8 parts.

[0086] Example 3 This embodiment provides a method for preparing a polyester matte masterbatch, which is basically the same as the steps in Example 1, except that the PET resin is 74.1 parts, the silane-modified silica is 20 parts, the acrylate core-shell microspheres are 1 part, the branched polycarbonate is 3 parts, and the ethylene bis-stearamide is 1 part.

[0087] Example 4 This embodiment provides a method for preparing a polyester matte masterbatch, which is basically the same as the steps in Example 1, except that the silane-modified silica prepared in Preparation Example 1 is replaced with the same amount of silane-modified silica prepared in Preparation Example 2.

[0088] Example 5 This embodiment provides a method for preparing a polyester matte masterbatch, which is basically the same as the steps in Example 1, except that the silane-modified silica prepared in Preparation Example 1 is replaced with the same amount of silane-modified silica prepared in Preparation Example 3.

[0089] Comparative Example 1 This comparative example provides a method for preparing polyester matte masterbatch, which is basically the same as the steps in Example 1, except that the addition of acrylate core-shell microspheres is omitted and the weight of PET resin is 87.7 parts.

[0090] Comparative Example 2 This comparative example provides a method for preparing a polyester matte masterbatch, which is basically the same as the steps in Example 2, except that the silane-modified silica prepared in Preparation Example 1 is replaced with the same weight of the silane-modified silica prepared in Preparation Example 4.

[0091] Comparative Example 3 This comparative example provides a method for preparing a polyester matte masterbatch, which is basically the same as the steps in Example 3, except that the addition of branched polycarbonate is omitted and the weight of PET resin is 77.1 parts.

[0092] Comparative Example 4 This comparative example provides a method for preparing a polyester matte masterbatch, which is basically the same as the steps in Example 2, except that the silane-modified silica prepared in Preparation Example 1 is replaced with the same weight of silica with a median particle size of 3 μm.

[0093] Experimental Example 1 Viscosity and pressure difference tests were performed on the polyester matte masterbatches prepared in Examples 1-5 and Comparative Examples 1-4. The results are shown in Table 1. Viscosity: The viscosity was measured using an IVS300 automatic Ubbelohde viscosity measurement system in accordance with GB / T 14190-2017. Differential pressure: Measured using a Dongguan Baopin filter press in accordance with ISO 23900-5:2015.

[0094] Table 1. Performance test results of the polyester matte masterbatch prepared in each example and comparative example.

[0095] As can be seen from Table 1, the polyester matte masterbatch prepared by this invention has a uniform viscosity of 0.56 dL / g-0.59 dL / g and a small pressure difference of 1.2 bar-5.2 bar. In Comparative Example 2, the silane-modified silica has a larger particle size, resulting in more severe screen clogging. In Comparative Example 3, the melt strength modifier was omitted, resulting in a lower viscosity of the polyester matte masterbatch. In Comparative Example 4, the silane-modified silica was replaced with the same amount of silica by weight, resulting in poor compatibility with PET resin, severe agglomeration of the masterbatch, and clogging of the filter screen.

[0096] Experimental Example 2 Polyester matte masterbatches prepared in Examples 1-5 and Comparative Examples 1-4 were combined with PET resin to prepare a polyester film. The polyester film included a first matte layer, a core layer, and a second matte layer stacked sequentially. The content of the polyester matte masterbatch in the first matte layer, the core layer, and the second matte layer, based on the total weight of the polyester film, was 6 wt%, 1 wt%, and 6 wt%, respectively. Specifically, the core layer raw material mixture and the matte layer raw material mixture were prepared according to the above contents, and biaxially stretched using a three-layer co-extrusion BOPET production line with a longitudinal stretch ratio of 3 and a transverse stretch ratio of 3. After stretching, the film was heat-set at 210°C for 4 seconds to obtain a polyester film with a thickness of 50 μm. Then, the polyester films prepared in Examples 1-5 and Comparative Examples 1-4 were tested for haze, haze uniformity CV value, film breakage rate, and number of crystal points. The results are shown in Table 2. Specifically: Haze: Measured according to GB / T 2410-2008; Haze uniformity: Take 10 points at equal intervals along the width of the BOPET film, and measure the haze value of each point according to GB / T 2410-2008. Calculate the coefficient of variation (CV value) according to the formula CV=(SD / Mean)×100%, where SD is the sample standard deviation and Mean is the mean. Film breakage rate: During the continuous production of BOPET film, the number of film breaks caused by melt rupture and thickness fluctuations within 24 hours is counted. Film breakage rate = (number of film breaks in the statistical period / total duration of the statistical period) × 100%, unit: times / 24h; Number of crystal points: Five crystal points with an area of ​​1m² were randomly selected from the surface of the BOPET film. 2 The samples were visually inspected under transmitted light, and the number of crystal points with a diameter ≥ 0.2 mm was counted. The arithmetic mean was taken, with the unit being points / m. 2 .

[0097] Table 2. Performance test results of the polyester matte masterbatch prepared in the examples and comparative examples.

[0098] As can be seen from Table 2, the films prepared in Examples 1-5 of this invention all achieved a haze ≥90.7%, haze uniformity ≤1.6%, film breakage rate of 0, and a relatively small number of crystal points, at 2 per m. 2 -3 pieces / m 2In Comparative Example 1, omitting the addition of acrylate core-shell microspheres had a relatively small impact on the viscosity and pressure difference of the polyester matte masterbatch, but resulted in poor haze and haze uniformity of the polyester film, with a higher number of crystal points. In Comparative Example 2, the silane-modified silica had a larger particle size and poorer processing stability, leading to significantly poorer haze uniformity, a higher breakage rate, and a higher number of crystal points in the polyester film. In Comparative Example 3, without the addition of a melt strength modifier, the melt strength of the PET system filled with high-content silica was severely insufficient. During the extrusion and biaxial stretching of BOPET film, the melt, due to its low strength, could not withstand high-speed tensile stress, resulting in frequent fractures and a significantly increased breakage rate. Simultaneously, insufficient melt strength caused unstable extrusion flow, uneven shear field distribution, and the formation of gel particles in some areas, significantly increasing the number of crystal points in the film. Furthermore, the thickness uniformity of the melt was difficult to maintain during stretching, and the differences in stretching ratio and crystallization behavior in different regions increased, ultimately leading to a significant deterioration in the overall haze and haze uniformity of the film. In Comparative Example 4, the silane-modified silica was replaced with the same amount of silica by weight. The dispersion was poor, resulting in significantly poorer haze and haze uniformity of the polyester film, higher film breakage rate, and more crystal points.

[0099] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A polyester matte masterbatch, characterized in that, By weight, the raw materials of the polyester matte masterbatch include: 70-95 parts of polyethylene terephthalate resin, 1-20 parts of silane-modified silica, 1-5 parts of acrylate core-shell microspheres, 1-5 parts of melt strength modifier, 0.1-2 parts of dispersant, 0.1-2 parts of antioxidant, and 0.5-2 parts of anti-hydrolysis agent; The median particle size of the silane-modified silica is 2.5 μm-4 μm.

2. The polyester matte masterbatch according to claim 1, characterized in that, The intrinsic viscosity of the polyethylene terephthalate resin is 0.65 dL / g-0.70 dL / g, and the melting point is 240℃-260℃. And / or, the silane-modified silica has a pore volume of 0.8 mL / g-1.2 mL / g and a maximum particle size of 5 μm-12 μm; And / or, the acrylate core-shell microspheres have a particle size of 100nm-500nm and a thermal decomposition temperature of 260℃-300℃; And / or, the melt strength modifier has a melt flow rate of 2 g / 10 min to 5 g / 10 min at 300 °C and 1.2 kg.

3. The polyester matte masterbatch according to claim 1, characterized in that, The preparation method of the acrylate core-shell microspheres includes: (1) reacting the first core layer monomer, the first emulsifier, the first initiator and the first crosslinking agent to obtain a seed emulsion; (2) After pre-emulsifying the second core layer monomer, the second emulsifier, the second initiator and the second crosslinking agent, they are added dropwise to the seed emulsion. After the second reaction, the core layer emulsion is obtained. (3) After pre-emulsifying the shell monomer, the third emulsifier, the third initiator and the third crosslinking agent, the mixture is added dropwise to the core emulsion. After the third reaction, the acrylate core-shell microspheres are obtained. The first core layer monomer, the second core layer monomer, and the shell layer monomer all include butyl acrylate and methyl methacrylate; In steps (1) and (2), the mass ratio of butyl acrylate to methyl methacrylate is independently 8.5-9.5:1; In step (3), the mass ratio of butyl acrylate to methyl methacrylate is 1:8.5-9.

5.

4. The polyester matte masterbatch according to claim 3, characterized in that, In step (3), the mass of the shell monomer is 35%-45% of the total mass of the first core monomer, the second core monomer, and the shell monomer; And / or, the mass ratio of the first core layer monomer to the second core layer monomer is 1:18-20; And / or, the mass ratio of the first core layer monomer, the first emulsifier, the first initiator, and the first crosslinking agent is 100:8-12:1-1.4:1.5-2.5; And / or, the mass ratio of the second core layer monomer, the second emulsifier, the second initiator, and the second crosslinking agent is 100:0.8-2:0.3-0.6:1.5-2.5; And / or, the mass ratio of the shell monomer, the third emulsifier, the third initiator, and the third crosslinking agent is 100:1-2:0.3-0.6:2.5-3.

5.

5. The polyester matte masterbatch according to claim 1, characterized in that, The method for preparing the silane-modified silica includes: heat-treating silica and a silane coupling agent.

6. The polyester matte masterbatch according to claim 5, characterized in that, The silane coupling agent includes at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane. And / or, the mass of the silane coupling agent is 1wt%-3wt% of the mass of the silicon dioxide; And / or, the heat treatment is performed at a temperature of 70°C-90°C for 1.5h-2.5h, and at a pH of 2.5-3.

5.

7. The polyester matte masterbatch according to claim 1, characterized in that, The melt strength modifier includes branched polycarbonate; And / or, the anti-hydrolysis agent includes at least one of polymerized carbodiimide and monomeric carbodiimide; And / or, the dispersant includes at least one of stearic acid, polyethylene wax, oxidized polyethylene wax, and ethylene bis-stearamide; And / or, the antioxidant comprises at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris[2,4-di-tert-butylphenyl] phosphite, bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite, and dioctadecyl thiodipropionate.

8. A method for preparing the polyester matte masterbatch according to any one of claims 1-7, characterized in that, Includes the following steps: Polyethylene terephthalate resin is fed into a twin-screw extruder through the main feed port. Silane-modified silica, acrylate core-shell microspheres, melt strength modifier, dispersant, antioxidant, and anti-hydrolysis agent are added into the twin-screw extruder through the side feed port. After mixing with polyethylene terephthalate resin, the mixture is extruded to obtain the polyester matte masterbatch.

9. The method for preparing polyester matte masterbatch according to claim 8, characterized in that, The melting temperature of the polyethylene terephthalate resin is 240℃-280℃; And / or, the mixing temperature is 200℃-260℃; And / or, the vacuum degree of the extrusion is -0.06MPa to -0.01MPa, and the material residence time is <150s; And / or, prior to extrusion, the process includes filtering the molten material using a 200-800 mesh filter.

10. The application of the polyester matte masterbatch prepared by the preparation method according to claim 8 or 9 in polyester film.

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