High-temperature-resistant antistatic multilayer copolyester film, preparation method and application thereof

Abstract

The present application relates to the technical field of multilayer copolyester film, and discloses a high-temperature-resistant antistatic multilayer copolyester film and a preparation method and application thereof, the multilayer copolyester film comprises an ABA three-layer structure obtained by melt co-extrusion; the raw material of the A layer is 5-30% of an opening agent master batch and the balance of a modified copolyester in terms of mass percentage; the raw material of the B layer is the modified copolyester; the modified copolyester is prepared by esterification reaction and polycondensation reaction from a binary acid mixture, a binary alcohol mixture and a catalyst; the binary acid mixture comprises furan dicarboxylic acid and 2,2'-bifuran-5,5'-dicarboxylic acid, and the binary alcohol mixture comprises ethylene glycol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1,4-cyclohexanedimethanol; the present application takes the modified copolyester as the main raw material, gives the film good temperature resistance through copolymerization modification, and enables the film to have stable and durable antistatic performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of multilayer copolyester film, and in particular to a high-temperature-resistant and antistatic multilayer copolyester film, a preparation method and application thereof. BACKGROUND

[0002] Polyester film is made of polyethylene terephthalate (PET) material by melt extrusion and biaxial stretching. It has been widely used in the fields of electrical, insulation, packaging, transfer printing, display and window film, etc. due to its good mechanical properties, thermal properties and optical properties. 2,5-furan dicarboxylic acid (FDCA) is similar in structure to terephthalic acid (PTA), and FDCA is the only biobased platform compound with an aromatic ring plane and a rigid structure. It is mainly used to replace the benzene ring series compounds in the eight big oil-based platform compounds (triphenyl triene alkyne naphthalene). FDCA and its derivatives can be obtained by biological fermentation of biomass raw materials, and can be used as renewable raw materials to replace oil-based PTA to prepare aromatic polyester materials, which have certain advantages in barrier properties, etc.

[0003] However, polyester film is an insulating material, and the surface resistance is as high as 10 14 Ω. It is easy to accumulate static electricity during production or use, either by itself or by friction with other materials. These static electricity causes the polyester film to easily adsorb dust, affecting the light transmittance, haze and other properties of the product, and also causing a series of problems such as adhesion force reduction and poor adhesion of subsequent functional layers. Therefore, it is very important to endow polyester film with antistatic property. To solve this problem, existing antistatic technology mainly realizes antistatic property by adding antistatic agents or surface coating to polyester film. For example, the patent with publication number CN101318393A discloses an antistatic thick polyester film with ABA three-layer structure, which modifies the conductive property of polyester substrate. The core layer film has 97-99.5% polyester chips and 0.5-3% antistatic agent by weight percentage, and the surface layer film has 90-96% polyester chips and 4-10% antistatic agent. However, there are still obvious limitations, such as certain influence on the transparency and mechanical properties of polyester film, and the antistatic agent needs to migrate to the surface of polyester film to realize antistatic property, and the surface resistance is unstable and easy to be affected by the environment and fail.

[0004] In addition, during the reprocessing process such as coating of polyester film, the ordinary polyester film has poor temperature resistance and will deform after being heated, resulting in longitudinal uneven lines at the outlet position of the oven, which affects the product quality. The existing technical solutions to solve the problem mainly add nano / micron-sized inorganic or organic particles as nucleating agents in the core layer of polyester film to increase the crystallinity of polyester film, but the nucleating agents may aggregate to form crystal points, affecting the optical properties and appearance of the film. SUMMARY

[0005] In order to solve the above technical problems, the application provides a high-temperature-resistant antistatic multilayer copolyester film and a preparation method and application thereof, wherein modified copolyester is used as a main raw material, and the film is endowed with good temperature resistance through copolymerization modification, and the film has stable and durable antistatic performance, and fundamentally solves the problems of migration failure caused by external antistatic agents and incompatibility, optical performance and temperature resistance caused by nucleating agents.

[0006] The object of the application is achieved by the following technical solutions.

[0007] In a first aspect, the application provides a high-temperature-resistant antistatic multilayer copolyester film, wherein the multilayer copolyester film comprises an ABA three-layer structure obtained by melt co-extrusion; the raw material of the A layer is 5-30% of an opening agent master batch and the balance of modified copolyester; the raw material of the B layer is modified copolyester; the modified copolyester is prepared by esterification and polycondensation reaction of a binary acid mixture, a binary alcohol mixture and a catalyst; the binary acid mixture comprises 50-70% of furan dimethyl acid and 30-50% of 2,2'-bifuran-5,5'-dicarboxylic acid in terms of mole percentage, and the binary alcohol mixture comprises 20-30% of ethylene glycol, 30-40% of 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 30-40% of 1,4-cyclohexanedimethanol.

[0008] The film in the application uses modified copolyester as a main raw material, which endows the film with temperature resistance and antistatic performance through copolymerization modification. Specifically, the binary acid in the modified copolyester comprises furan dimethyl acid (FDCA) and 2,2'-bifuran-5,5'-dicarboxylic acid (BFDCA), the ether oxygen bond on the furan ring carries a lone pair of electrons and has the ability to accept protons, which can realize static dissipation effect through internal proton transfer, effectively reducing the surface resistance of the copolyester film. FDCA is compounded with functional furan derivative BFDCA, breaking through the performance limit of single FDCA, and the bifuran structure of BFDCA can enhance the conjugated system, further reducing the surface resistance. However, when the proportion of BFDCA is too high, the molecular weight distribution of the copolyester is wide, which will affect the temperature resistance of the film.

[0009] The diols in the modified copolyester include ethylene glycol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) and 1,4-cyclohexanedimethanol (CHDM), the tetra-ring in CBDO has greater rigidity, which is beneficial to improve the temperature resistance of the polyester film. When CHDM is used to synthesize copolyester, the molecular chain growth rate can be faster, the copolyester molecular weight distribution is narrowed, which is also beneficial to improve the temperature resistance of the polyester film. In addition, the non-planar structure of the six-membered ring in CHDM can improve the toughness of the polyester film to a greater extent, and by introducing ethylene glycol as a flexible structural unit, the processing stability of the film in the biaxial stretching process is improved. By controlling the molar ratio of FDCA, BFDCA, CBDO and CHDM within a reasonable range, the antistatic property and temperature resistance of the polyester film can be synergistically improved, and a high-temperature-resistant antistatic copolyester film with excellent comprehensive performance can be prepared.

[0010] As preferred, the molar ratio of the diol mixture and the diacid mixture is 1.05-1.2:1.

[0011] As preferred, the molar ratio of the catalyst and the diacid mixture is 1-10:1000.

[0012] As preferred, the catalyst includes one or more of tetrabutyl titanate, isopropyl titanate, titanium acetate, titanium tetrachloride, stannous octoate, stannous oxalate, stannous chloride, stannous oxide, ethylene glycol antimony, antimony trioxide and antimony acetate.

[0013] As preferred, the temperature of the esterification reaction is 210-230℃, the pressure is 0.30-0.40MPa, and when the water output reaches 98% or more, the polycondensation reaction stage is entered.

[0014] As preferred, the temperature of the polycondensation reaction is 250-260℃, the vacuum degree is 20-60Pa, and the reaction time is 3-4h.

[0015] As preferred, the intrinsic viscosity of the modified copolyester is 0.6-0.7dL / g.

[0016] As preferred, the raw material of the opening agent master batch includes PET and opening agent particles, and the intrinsic viscosity is 0.6-0.7dl / g.

[0017] As preferred, the content of the opening agent particles is 3000-10000ppm of the mass of the opening agent master batch, and the particle size is 1-4μm; the opening agent particles are inorganic particles, and more preferably are silica particles.

[0018] The plastic film without opening agent is difficult to open after winding and winding, and is easy to stick after heating or pressure, which affects the subsequent use and processing. The role of the opening agent is to form micro-protrusions on the surface of the film, reduce the adhesion between the films and the equipment, and make the plastic film easy to separate, so the opening agent master batch is only added to the surface layer.

[0019] If the amount of opening agent master batch added is too little, the opening effect is not obvious, and if the amount of opening agent master batch added is too much, the inorganic particles will affect the optical properties. The thicker the thickness of layer A, the more opening agent needs to be added to achieve good opening effect, and the total number of inorganic particles in the system increases, but too much will cause the haze of the film to rise significantly and the light transmittance to decrease. Therefore, the amount of opening agent master batch added in layer A needs to match the thickness of layer A to obtain better comprehensive performance and expand the application range.

[0020] Preferably, the thickness of the multilayer copolyester film is 25-150 μm; and the thickness ratio of the ABA three-layer structure is 10-15%:70-80%:10-15%.

[0021] In a second aspect, the application provides a preparation method of a high-temperature-resistant and antistatic multilayer copolyester film, comprising the following steps: adding A-layer raw materials and B-layer raw materials into an extruder, melt-extruding three layers, and then casting to form a cast sheet; and then performing longitudinal stretching, transverse stretching, setting, and cooling on the cast sheet in sequence to obtain the multilayer copolyester film.

[0022] Preferably, the extrusion temperature of the co-extrusion is 265-285℃.

[0023] Preferably, the casting is performed on a cast roll, and the temperature of the cast roll is 15-30℃.

[0024] Preferably, the temperature of the longitudinal stretching is 75-110℃, and the stretching multiple is 2.8-4.0 times; and the temperature of the transverse stretching is 95-145℃, and the stretching multiple is 3.0-4.5 times.

[0025] Preferably, the setting temperature is 220-240℃.

[0026] Preferably, the cooling temperature is 45-100℃.

[0027] In a third aspect, the application provides a use of the high-temperature-resistant and antistatic multilayer copolyester film in a release film.

[0028] The copolyester film product prepared by the application has excellent temperature resistance and antistatic property, and can be widely used in high-end protection / release films (such as MLCC release films), window films, and the like.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] (1) The prior art regards antistatic and temperature resistance as independent problems. The present application replaces physical blending with copolymerization molecular design, fundamentally solving the problems of migration failure caused by external antistatic agents, incompatibility, optical performance and temperature resistance reduction caused by nucleating agents, etc.

[0031] (2) The antistatic performance of the film is regulated by copolymerization modification, avoiding the problem of coating peeling off in some specific environments, so that the film has stable and durable antistatic performance.

[0032] (3) Using bio-based furan dicarboxylic acid and its derivatives as comonomers can reduce the consumption of petroleum resources, avoid impurity pollution during material recycling, improve recyclability, and meet the trend of green manufacturing. DETAILED DESCRIPTION

[0033] The technical solutions of the present application are illustrated below with specific examples, but the protection scope of the present application is not limited thereto.

[0034] 1. Modified copolyester

[0035] Furan dicarboxylic acid (FDCA) and 2,2'-bifuran-5,5'-dicarboxylic acid (BFDCA) with a molar percentage of 50-70%:30-50% are used as a binary acid mixture, and ethylene glycol (EG), 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) and 1,4-cyclohexanedimethanol (CHDM) with a molar percentage of 20-30%:30-40%:30-40% are used as a binary alcohol mixture. The catalyst includes one or more of tetrabutyl titanate, isopropyl titanate, titanium acetate, titanium tetrachloride, stannous octoate, stannous oxalate, stannous chloride, stannous oxide, ethylene glycol antimony, antimony trioxide and antimony acetate.

[0036] The binary acid mixture and the binary alcohol mixture are subjected to esterification under the action of the catalyst at a temperature of 210-230℃ and a pressure of 0.30-0.40MPa, the molar ratio of the binary alcohol mixture to the binary acid mixture is 1.05-1.2:1, and the molar ratio of the catalyst to the binary acid mixture is 1-10:1000. When the water output reaches 98% or more, the reaction enters the polycondensation stage. The temperature of the polycondensation reaction is 250-260℃, the vacuum degree is 20-60Pa, and the reaction time is 3-4h. After the reaction is completed, the modified copolyester is obtained, and the intrinsic viscosity is 0.6-0.7dL / g.

[0037] 2. Multilayer copolyester film

[0038] The raw materials of the A layer are 5-30% of the opening agent master batch and the rest of the modified copolyester by mass percentage, the opening agent master batch is prepared by mixing and melting PET and opening agent particles (particle size of 1-4 μm) and then cutting the particles, the content of the opening agent particles is 3000-10000 ppm of the mass of the opening agent master batch, and the intrinsic viscosity of the opening agent master batch is 0.6-0.7 dl / g. The raw materials of the B layer are the modified copolyester.

[0039] The raw materials of the A layer and the raw materials of the B layer are added to an extruder, and three layers are co-extruded, the extrusion temperature is 265-285℃, and after being extruded from the die, it is cast onto a casting roll, the temperature of the casting roll is 15-30℃, and a casting sheet is formed; the casting sheet is longitudinally stretched, the temperature is 75-110℃, and the stretching ratio is 2.8-4.0 times; then transversely stretched, the temperature is 95-145℃, and the stretching ratio is 3.0-4.5 times; the stretched film is shaped at 220-240℃, and then cooled at 45-100℃, after traction and winding, a multilayer copolyester film is obtained.

[0040] The high-temperature-resistant antistatic copolyester film is in ABA three-layer structure, the thickness is 25-150 μm, the thickness ratio of the A layer, the B layer and the A layer is 10-15%:70-80%:10-15%.

[0041] Example 1

[0042] 1. Modified copolyester

[0043] FDCA and BFDCA with a mole percentage of 50%:50% are used as a binary acid mixture, and EG, CBDO and CHDM with a mole percentage of 30%:30%:40% are used as a binary alcohol mixture. The catalyst is ethylene glycol antimony.

[0044] After the binary acid mixture, the binary alcohol mixture and the catalyst are mixed, they are added to a reaction kettle, and esterification is carried out under the conditions of 215℃ and 0.33 MPa, the mole ratio of the binary alcohol mixture to the binary acid mixture is 1.1:1, the mole ratio of the catalyst to the binary acid mixture is 5:1000, and when the water output reaches 98% or more, the reaction enters the polycondensation reaction stage. The temperature of the polycondensation reaction is 260℃, the vacuum degree is 40 Pa, and the reaction time is 3 h, after the reaction is completed, the modified copolyester is prepared.

[0045] 2. Multilayer copolyester film

[0046] The raw material of layer A is 20% of opening agent master batch and 80% of modified copolyester by mass percentage, the opening agent master batch is prepared by mixing and melting PET and opening agent particles (average particle size is 2.5 μm) and then cutting, the content of opening agent particles is 6000 ppm of the mass of opening agent master batch, and the intrinsic viscosity of opening agent master batch is 0.642 dl / g. The raw material of layer B is modified copolyester.

[0047] The raw material of layer A and the raw material of layer B are added into an extruder, and three layers are co-extruded, the extrusion temperature is 270 ℃, and the cast sheet is formed after being extruded from a die and cast onto a casting roll, the temperature of the casting roll is 22 ℃. The cast sheet is longitudinally stretched at a temperature of 95 ℃ and a stretching ratio of 3.0 times, and then transversely stretched at a temperature of 125 ℃ and a stretching ratio of 3.5 times. The stretched film is shaped at 220 ℃ and cooled at 60 ℃, and then a multilayer copolyester film is obtained after traction and winding.

[0048] The multilayer copolyester film has an ABA three-layer structure, and the thickness is 100 μm, the thickness ratio of layer A, layer B and layer A is 10%:80%:10%.

[0049] Example 2

[0050] The difference from example 1 is that the molar percentage of FDCA and BFDCA as a binary acid mixture is 60%:40% during the preparation of the modified copolyester.

[0051] 1. Modified copolyester

[0052] The molar percentage of FDCA and BFDCA as a binary acid mixture is 60%:40%, and the molar percentage of EG, CBDO and CHDM as a binary alcohol mixture is 30%:30%:40%. The catalyst is ethylene glycol antimony.

[0053] After mixing the binary acid mixture, the binary alcohol mixture and the catalyst, they are added into a reaction kettle, and esterification is carried out at 215 ℃ and 0.33 MPa, the molar ratio of the binary alcohol mixture to the binary acid mixture is 1.1:1, the molar ratio of the catalyst to the binary acid mixture is 5:1000, and when the water output reaches 98% or more, the reaction enters the polycondensation reaction stage. The temperature of the polycondensation reaction is 260 ℃, the vacuum degree is 40 Pa, and the reaction time is 3 h. After the reaction is completed, the modified copolyester is prepared.

[0054] 2. Multilayer copolyester film

[0055] The raw material of layer A is 20% of opening agent master batch and 80% of modified copolyester by mass percentage, the opening agent master batch is prepared by mixing and melting PET and opening agent particles (average particle size is 2.5 μm) and then cutting, the content of opening agent particles is 6000 ppm of the mass of opening agent master batch, and the intrinsic viscosity of opening agent master batch is 0.642 dl / g. The raw material of layer B is modified copolyester.

[0056] The raw materials of layer A and layer B are added into an extruder, and three layers are co-extruded, the extrusion temperature is 270 ℃, and the cast sheet is formed after being extruded from a die and cast onto a casting roll, the temperature of the casting roll is 22 ℃. The cast sheet is longitudinally stretched at a temperature of 90 ℃ and a stretching ratio of 2.8 times, and then transversely stretched at a temperature of 120 ℃ and a stretching ratio of 3.3 times. The stretched film is shaped at 220 ℃ and cooled at 60 ℃, and then a multilayer copolyester film is obtained after traction and winding.

[0057] The multilayer copolyester film has an ABA three-layer structure, and the thickness is 100 μm, the thickness ratio of layer A, layer B and layer A is 10%:80%:10%.

[0058] Example 3

[0059] The difference from example 1 is that EG, CBDO and CHDM with a molar percentage of 25%:40%:35% are used as a binary alcohol mixture in the preparation process of the modified copolyester.

[0060] 1. Modified copolyester

[0061] FDCA and BFDCA with a molar percentage of 50%:50% are used as a binary acid mixture, and EG, CBDO and CHDM with a molar percentage of 25%:40%:35% are used as a binary alcohol mixture. The catalyst is ethylene glycol antimony.

[0062] After the binary acid mixture, the binary alcohol mixture and the catalyst are mixed, they are added into a reaction kettle, and esterification is carried out under the conditions of 215 ℃ and 0.33 MPa, the molar ratio of the binary alcohol mixture to the binary acid mixture is 1.1:1, the molar ratio of the catalyst to the binary acid mixture is 5:1000, and when the water output reaches 98% or more, the reaction enters the polycondensation reaction stage. The temperature of the polycondensation reaction is 260 ℃, the vacuum degree is 40 Pa, and the reaction time is 3 h. After the reaction is completed, the modified copolyester is prepared.

[0063] 2. Multilayer copolyester film

[0064] The raw material of the A layer is 20% of the opening agent master batch and 80% of the modified copolyester by mass percentage, the opening agent master batch is prepared by mixing and melting PET and opening agent particles (average particle size is 2.5 μm) and then pelletizing, the content of the opening agent particles is 6000 ppm of the mass of the opening agent master batch, and the intrinsic viscosity of the opening agent master batch is 0.642 dl / g. The raw material of the B layer is the modified copolyester.

[0065] The raw material of the A layer and the raw material of the B layer are added into an extruder, and three-layer co-extrusion is carried out at an extrusion temperature of 270°C, and then the extruded material is cast onto a casting roller at a temperature of 22°C to form a cast sheet. The cast sheet is longitudinally stretched at a temperature of 100°C with a stretching ratio of 3.0, and then transversely stretched at a temperature of 135°C with a stretching ratio of 3.6. The stretched film is shaped at 220°C and cooled at 60°C, and then drawn and wound to obtain a multilayer copolyester film.

[0066] The multilayer copolyester film has an ABA three-layer structure, and the thickness ratio of the A layer, the B layer and the A layer is 10%:80%:10%.

[0067] Example 4

[0068] The difference from Example 1 is that, in the preparation of the copolyester film, the raw material of the A layer is 30% of the opening agent master batch and 70% of the modified copolyester by mass percentage.

[0069] The raw material of the A layer is 30% of the opening agent master batch and 70% of the modified copolyester by mass percentage, the opening agent master batch is prepared by mixing and melting PET and opening agent particles (average particle size is 2.5 μm) and then pelletizing, the content of the opening agent particles is 6000 ppm of the mass of the opening agent master batch, and the intrinsic viscosity of the opening agent master batch is 0.642 dl / g. The raw material of the B layer is the modified copolyester.

[0070] The raw material of the A layer and the raw material of the B layer are added into an extruder, and three-layer co-extrusion is carried out at an extrusion temperature of 270°C, and then the extruded material is cast onto a casting roller at a temperature of 22°C to form a cast sheet. The cast sheet is longitudinally stretched at a temperature of 100°C with a stretching ratio of 3.0, and then transversely stretched at a temperature of 135°C with a stretching ratio of 3.6. The stretched film is shaped at 220°C and cooled at 60°C, and then drawn and wound to obtain a multilayer copolyester film.

[0071] The multilayer copolyester film has an ABA three-layer structure, and the thickness ratio of the A layer, the B layer and the A layer is 10%:80%:10%.

[0072] Example 5

[0073] The difference from Example 1 is that the raw material of the A layer is 5% of the opening agent master batch and 95% of the modified copolyester in terms of mass percentage, and the copolyester film has a thickness of 50 μm.

[0074] The raw material of the A layer is 5% of the opening agent master batch and 95% of the modified copolyester in terms of mass percentage, and the opening agent master batch is prepared by mixing and melting PET and opening agent particles (with an average particle size of 2.5 μm) and then cutting the particles, the content of the opening agent particles is 6000 ppm of the mass of the opening agent master batch, and the intrinsic viscosity of the opening agent master batch is 0.642 dl / g. The raw material of the B layer is the modified copolyester.

[0075] The raw material of the A layer and the raw material of the B layer are added into an extruder to melt three-layer co-extrusion, the extrusion temperature is 270°C, and the extruded material is cast onto a casting roll after extruding from a die, the temperature of the casting roll is 22°C, and a cast sheet is formed; the cast sheet is stretched in the longitudinal direction, the temperature is 95°C, and the stretching multiple is 3.0 times; then the cast sheet is stretched in the transverse direction, the temperature is 125°C, and the stretching multiple is 3.5 times; the stretched film is shaped at 220°C, and then cooled at 60°C, and after traction and winding, a multilayer copolyester film is obtained.

[0076] The multilayer copolyester film has an ABA three-layer structure, and the thickness is 50 μm, the thickness ratio of the A layer, the B layer and the A layer is 10%:80%:10%.

[0077] Comparative Example 1

[0078] The difference from Example 1 is that the modified copolyester is replaced by PET chips (with an intrinsic viscosity of 0.664 dl / g) to prepare the copolyester film.

[0079] The raw material of the A layer is 20% of the opening agent master batch and 80% of the PET chips in terms of mass percentage, and the opening agent master batch is prepared by mixing and melting PET and opening agent particles (with an average particle size of 2.5 μm) and then cutting the particles, the content of the opening agent particles is 6000 ppm of the mass of the opening agent master batch, and the intrinsic viscosity of the opening agent master batch is 0.642 dl / g. The raw material of the B layer is the PET chips.

[0080] The raw material of the A layer and the raw material of the B layer are added into an extruder to melt three-layer co-extrusion, the extrusion temperature is 270°C, and the extruded material is cast onto a casting roll after extruding from a die, the temperature of the casting roll is 22°C, and a cast sheet is formed; the cast sheet is stretched in the longitudinal direction, the temperature is 95°C, and the stretching multiple is 3.0 times; then the cast sheet is stretched in the transverse direction, the temperature is 125°C, and the stretching multiple is 3.5 times; the stretched film is shaped at 220°C, and then cooled at 60°C, and after traction and winding, a multilayer copolyester film is obtained.

[0081] The multilayer copolyester film has an ABA three-layer structure, and the thickness is 100 μm. The thickness ratio of the A layer, the B layer, and the A layer is 10%:80%:10%.

[0082] Comparative Example 2

[0083] Different from Example 1 is that only FDCA is used as the diacid in the preparation of the modified copolyester.

[0084] 1. Modified copolyester

[0085] FDCA is used as the diacid, and EG, CBDO, and CHDM with a molar percentage of 30%:30%:40% are used as the diol mixture. The catalyst is ethylene glycol antimony.

[0086] After the diacid, the diol mixture, and the catalyst are mixed, they are added to a reaction kettle, and esterification is carried out at 215°C and 0.33 MPa. The molar ratio of the diol mixture to the diacid is 1.1:1, and the molar ratio of the catalyst to the diacid is 5:1000. When the water output reaches 98% or more, the reaction enters the polycondensation reaction stage. The temperature of the polycondensation reaction is 260°C, the vacuum degree is 40 Pa, and the reaction time is 3 h. After the reaction is completed, the modified copolyester is obtained.

[0087] 2. Multilayer copolyester film

[0088] The raw materials of the A layer are 20% of the opening agent master batch and 80% of the modified copolyester by mass percentage. The opening agent master batch is prepared by mixing and melting PET and opening agent particles (with an average particle size of 2.5 μm) and then cutting the particles. The content of the opening agent particles in the opening agent master batch is 6000 ppm of the mass of the opening agent master batch, and the intrinsic viscosity of the opening agent master batch is 0.642 dl / g. The raw materials of the B layer are the modified copolyester.

[0089] The raw materials of the A layer and the raw materials of the B layer are added to an extruder, and three-layer co-extrusion is carried out at a temperature of 270°C. After being extruded from a die, the material is cast onto a casting roll, and the temperature of the casting roll is 22°C. The cast sheet is then stretched longitudinally at a temperature of 85°C and a stretching ratio of 3.1 times. Then, the stretched sheet is stretched transversely at a temperature of 125°C and a stretching ratio of 3.7 times. The stretched film is then shaped at 220°C and cooled at 60°C. After being pulled and wound up, the multilayer copolyester film is obtained.

[0090] The multilayer copolyester film has an ABA three-layer structure, and the thickness is 100 μm. The thickness ratio of the A layer, the B layer, and the A layer is 10%:80%:10%.

[0091] Comparative Example 3

[0092] The difference from Example 1 is that, in the preparation of the modified copolyester, FDCA and BFDCA with a molar percentage of 40%:60% are used as a binary acid mixture.

[0093] 1. Modified copolyester

[0094] FDCA and BFDCA with a molar percentage of 50%:50% are used as a binary acid mixture, and EG, CBDO and CHDM with a molar percentage of 30%:30%:40% are used as a binary alcohol mixture. The catalyst is ethylene glycol antimony.

[0095] After mixing the binary acid mixture, the binary alcohol mixture and the catalyst, they are added to a reaction kettle, and esterification is carried out at 215°C and 0.33 MPa. The molar ratio of the binary alcohol mixture to the binary acid mixture is 1.1:1, and the molar ratio of the catalyst to the binary acid mixture is 5:1000. When the water output reaches 98% or more, the reaction enters the polycondensation reaction stage. The temperature of the polycondensation reaction is 260°C, the vacuum degree is 40 Pa, and the reaction time is 3 h. After the reaction is completed, the modified copolyester is obtained.

[0096] 2. Multilayer copolyester film

[0097] The raw materials of the A layer are 20% of an opening agent master batch and 80% of the modified copolyester, by mass percentage. The opening agent master batch is prepared by mixing and melting PET and opening agent particles (with an average particle size of 2.5 μm) and then cutting the particles. The content of the opening agent particles is 6000 ppm of the mass of the opening agent master batch, and the intrinsic viscosity of the opening agent master batch is 0.642 dl / g. The raw materials of the B layer are the modified copolyester.

[0098] The raw materials of the A layer and the raw materials of the B layer are added to an extruder, and three-layer co-extrusion is carried out at a temperature of 270°C. After being extruded from a die, the material is cast onto a casting roll with a temperature of 22°C to form a cast sheet. The cast sheet is subjected to longitudinal stretching at a temperature of 105°C with a stretching ratio of 3.0 times, and then subjected to transverse stretching at a temperature of 140°C with a stretching ratio of 3.4 times. The stretched film is shaped at 220°C and cooled at 60°C. After being pulled and wound up, the multilayer copolyester film is obtained.

[0099] The multilayer copolyester film has an ABA three-layer structure and a thickness of 100 μm. The thickness ratio of the A layer, the B layer and the A layer is 10%:80%:10%.

[0100] Comparative Example 4

[0101] The difference from Example 1 is that, in the preparation of the modified copolyester, EG and CBDO with a molar percentage of 30%:70% are used as a binary alcohol mixture.

[0102] 1. Modified copolyester

[0103] FDCA and BFDCA were mixed as a binary acid mixture with a molar percentage of 50%:50%, and EG and CBDO were mixed as a binary alcohol mixture with a molar percentage of 30%:70%. The catalyst was ethylene glycol antimony.

[0104] After mixing the binary acid mixture, the binary alcohol mixture, and the catalyst, they were added to a reaction kettle, and esterification was carried out at 215°C and 0.33 MPa. The molar ratio of the binary alcohol mixture to the binary acid mixture was 1.1:1, and the molar ratio of the catalyst to the binary acid mixture was 5:1000. When the water output reached 98% or more, the reaction entered the polycondensation reaction stage. The polycondensation reaction was carried out at a temperature of 260°C, a vacuum degree of 40 Pa, and a reaction time of 3 h. After the reaction was completed, the modified copolyester was obtained.

[0105] 2. Multilayer copolyester film

[0106] The raw materials of layer A were 20% of an opening agent master batch and 80% of the modified copolyester, according to the mass percentage. The opening agent master batch was prepared by mixing and melting PET and opening agent particles (with an average particle size of 2.5 μm) and then cutting the particles. The content of the opening agent particles was 6000 ppm of the mass of the opening agent master batch, and the intrinsic viscosity of the opening agent master batch was 0.642 dl / g. The raw materials of layer B were the modified copolyester.

[0107] The raw materials of layer A and layer B were added to an extruder, and three layers were co-extruded at a melt temperature of 270°C. After being extruded from a die, the material was cast onto a casting roll, which was at a temperature of 22°C. The material was then longitudinally stretched at a temperature of 105°C with a stretching ratio of 2.8 times, and then transversely stretched at a temperature of 135°C with a stretching ratio of 3.8 times. The stretched film was then set at a temperature of 220°C and cooled at a temperature of 60°C. After being pulled and wound up, the multilayer copolyester film was obtained.

[0108] The multilayer copolyester film had an ABA three-layer structure and a thickness of 100 μm. The thickness ratio of layer A, layer B, and layer A was 10%:80%:10%.

[0109] Comparative Example 5

[0110] The difference between this example and Example 1 was that, during the preparation of the modified copolyester, EG, CBDO, and CHDM were mixed as a binary alcohol mixture with a molar percentage of 30%:20%:50%.

[0111] 1. Modified copolyester

[0112] FDCA and BFDCA with a molar percentage of 50%:50% were used as a binary acid mixture, and EG, CBDO, and CHDM with a molar percentage of 30%:20%:50% were used as a binary alcohol mixture. The catalyst was ethylene glycol antimony.

[0113] After mixing the binary acid mixture, the binary alcohol mixture, and the catalyst, they were added to a reaction kettle, and esterification was carried out at 215°C and 0.33 MPa. The molar ratio of the binary alcohol mixture to the binary acid mixture was 1.1:1, and the molar ratio of the catalyst to the binary acid mixture was 5:1000. When the water output reached 98% or more, the reaction entered the polycondensation reaction stage. The temperature of the polycondensation reaction was 260°C, the vacuum degree was 40 Pa, and the reaction time was 3 h. After the reaction was completed, the modified copolyester was obtained.

[0114] 2. Multilayer copolyester film

[0115] The raw materials of the A layer were 20% of an opening agent master batch and 80% of the modified copolyester, according to the mass percentage. The opening agent master batch was prepared by mixing and melting PET and opening agent particles (with an average particle size of 2.5 μm) and then cutting the particles. The content of the opening agent particles was 6000 ppm of the mass of the opening agent master batch, and the intrinsic viscosity of the opening agent master batch was 0.642 dl / g. The raw materials of the B layer were the modified copolyester.

[0116] The raw materials of the A layer and the raw materials of the B layer were added to an extruder, and three layers were co-extruded at a melt temperature of 270°C. After being extruded from a die, the material was cast onto a casting roll with a temperature of 22°C to form a cast sheet. The cast sheet was stretched longitudinally at a temperature of 95°C with a stretching ratio of 3.3 times, and then it was stretched transversely at a temperature of 125°C with a stretching ratio of 4.1 times. The stretched film was shaped at 220°C and then cooled at 60°C. After being pulled and wound up, the multilayer copolyester film was obtained.

[0117] The multilayer copolyester film had an ABA three-layer structure and a thickness of 100 μm. The thickness ratio of the A layer, the B layer, and the A layer was 10%:80%:10%.

[0118] Performance test:

[0119] (1) Thickness test: GB / T 33399-2016;

[0120] (2) Glass transition temperature: GB / T 19466.2-2004;

[0121] (3) Surface resistance test: GB / T 33398-2016;

[0122] (4) Surface resistance test after aging: After the sample was kept at a temperature of 60°C and a humidity of 90% for 200 h, the surface resistance was tested.

[0123] (5) Temperature resistance test: the copolyester film roll sample with a width of 1000 mm is observed for surface flatness after passing through an oven with a length of 32 m and an ambient temperature of 160℃ at a speed of 40 m / min under a pulling tension of 15 N / m. The higher the flatness, the better the temperature resistance of the copolyester film. "O" represents excellent temperature resistance; "△" represents good temperature resistance; and "X" represents poor temperature resistance.

[0124] Table 1 Performance test data of Examples 1-5 and Comparative Examples 1-5

[0125]

[0126] As shown in Table 1, the film in the present application uses modified copolyester as the main raw material. The modified copolyester gives the film good temperature resistance and antistatic properties through copolymerization modification, and can still maintain good antistatic properties after aging, solving the problem of easy aging and falling off caused by conventional antistatic coating. The copolyester film prepared by the method in the present application in Examples 1-5 can obviously obtain more excellent temperature resistance and antistatic properties compared with the film prepared by conventional polyester in Comparative Example 1.

[0127] Comparative Example 2 only uses FDCA as a diacid in the preparation process of the modified copolyester, which can achieve certain antistatic effect compared with Comparative Example 1. However, the modified copolyester obtained after the reaction of FDCA with the diol mixture may be affected by the structure of the obtained polyester molecular chain, the internal proton transfer effect is limited, and the antistatic effect obtained is limited. In Comparative Example 3, the molar ratio of BFDCA added is too large, which will cause the molecular weight distribution of the copolyester to be wide, the proportion of low molecular weight molecular chains is large, and the glass transition temperature of the modified copolyester is low, thereby affecting the temperature resistance of the film.

[0128] Comparative Example 4 does not add CHDM in the preparation process of the modified copolyester, which will also cause the molecular weight distribution of the copolyester to be wide and the glass transition temperature to be low, thereby the temperature resistance of the film is poor. In Comparative Example 5, the molar ratio of CBDO added is too small. CBDO tetra ring has large rigidity, which can improve the temperature resistance of the polyester film, and too little addition will result in poor temperature resistance.

[0129] The above is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent flow transformation made by using the present application specification, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the present application.

Claims

1. A high heat resistant antistatic multilayer copolyester film, characterized by, The multilayer copolyester film comprises an ABA three-layer structure obtained by melt co-extrusion; the raw material of the A layer is 5-30% of an opening agent master batch and the balance of a modified copolyester, by mass percentage; the raw material of the B layer is the modified copolyester; the modified copolyester is prepared by esterification reaction and polycondensation reaction of a binary acid mixture, a binary alcohol mixture and a catalyst; the binary acid mixture comprises 50-70% of furan dicarboxylic acid and 30-50% of 2,2'-bifuran-5,5'-dicarboxylic acid, by mole percentage; and the binary alcohol mixture comprises 20-30% of ethylene glycol, 30-40% of 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 30-40% of 1,4-cyclohexanedimethanol.

2. The high temperature resistant antistatic multilayer copolyester film according to claim 1, wherein, The molar ratio of the binary alcohol mixture to the binary acid mixture is 1.05-1.2:

1.

3. The high temperature resistant antistatic multilayer copolyester film according to claim 1 or 2, characterized in that, The molar ratio of the catalyst to the binary acid mixture is 1-10:1000.

4. The high temperature resistant antistatic multilayer copolyester film according to claim 1, wherein, The esterification reaction is carried out at a temperature of 210-230°C and a pressure of 0.30-0.40 MPa, and when the water output reaches 98% or above, the polycondensation reaction stage is entered.

5. The high temperature resistant antistatic multilayer co-polyester film according to claim 1 or 4, characterized in that, The polycondensation reaction is carried out at a temperature of 250-260°C and a vacuum degree of 20-60 Pa, and the reaction time is 3-4 h.

6. The high temperature resistant antistatic multilayer co-polyester film according to claim 1, wherein, The raw material of the opening agent master batch comprises PET and opening agent particles, and the intrinsic viscosity is 0.6-0.7 dl / g; the content of the opening agent particles is 3000-10000 ppm of the mass of the opening agent master batch, and the particle size is 1-4 μm.

7. The high temperature resistant antistatic multilayer co-polyester film according to claim 1 or 6, characterized in that, The thickness of the multilayer copolyester film is 25-150 μm; and the thickness ratio of the ABA three-layer structure is 10-15%:70-80%:10-15%.

8. A process for the production of the high temperature resistant antistatic multilayer copolyester film according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: adding the raw material of the A layer and the raw material of the B layer into an extruder, melt co-extruding three layers, and then casting to form a cast sheet; and then performing longitudinal stretching, transverse stretching, setting and cooling on the cast sheet in sequence to obtain the multilayer copolyester film.

9. The preparation method according to claim 8, characterized in that, The temperature of the longitudinal stretching is 75-110°C, and the stretching multiple is 2.8-4.0 times; and the temperature of the transverse stretching is 95-145°C, and the stretching multiple is 3.0-4.5 times.

10. Application of the high temperature-resistant antistatic multilayer copolyester film according to any one of claims 1-7 or prepared by the method according to any one of claims 8-9 to a release film.

Images