Polyester film and its manufacturing method

Abstract

To provide a polyester film and a method for producing the same.SOLUTION: There is provided a polyester film which comprises a physically recycled polyester resin and a chemically recycled polyester resin. The physically recycled polyester resin is formed of physically recycled polyester chips and the physically recycled polyester chips have a first intrinsic viscosity. The chemically recycled polyester resin is formed of chemically recycled polyester chips and the chemically recycled polyester chips have a second intrinsic viscosity. The physically recycled polyester chips and the chemically recycled polyester chips are mixed each other and then mixed and extruded according to a predetermined intrinsic viscosity so that a polyester film has a predetermined intrinsic viscosity.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a polyester film and a method for producing the same, and more particularly to a polyester film using both physically recycled polyester resins and chemically recycled polyester resins and a method for producing the same. [Background technology]

[0002] Conventionally, the main method for recycling waste polyethylene terephthalate (PET) bottles is the physical recycling method (also called the mechanical recycling method). The physical recycling method mainly includes the following: First, the waste material of the PET bottles is physically and mechanically crushed. Next, the crushed PET bottle waste is melted under a high temperature environment. Next, the melted PET bottle waste is granulated to form physically recycled polyester chips. This physically recycled polyester chips can be used for subsequent processing. Summary of the Invention [Problem to be solved by the invention]

[0003] The physically recycled polyester chips produced by the physical recycling method usually have a relatively high intrinsic viscosity (IV). To adjust the intrinsic viscosity of the physically recycled polyester chips, the method mainly used in the related art is solid-state polymerization. However, the solid-state polymerization method may only be used to increase the intrinsic viscosity of the physically recycled polyester chips, and may not be used to decrease the intrinsic viscosity of the physically recycled polyester chips. In addition, in a general film manufacturing process, the intrinsic viscosity of the polyester chips is usually limited to a certain range. The physically recycled polyester chips produced by the physical recycling method are usually only applicable to the bottle blowing process or the spinning process, and cannot be applied to the film manufacturing process.

[0004] In order to adapt the physically recycled polyester chips to the film manufacturing process, the method mainly used in the related art is to reduce the overall intrinsic viscosity of the polyester material by mixing the physically recycled polyester chips with additional virgin polyester chips. However, such a method cannot effectively increase the proportion of recycled polyester material used in the polyester film, so the final polyester film product may not meet the requirements for environmental protection. That is, the proportion of recycled polyester is limited to a certain extent in the existing polyester film, and this problem needs to be solved.

[0005] Accordingly, the present invention provides a method for producing a polyester film. [Means for solving the problem]

[0006] In one embodiment, the present invention provides a method for the preparation of a method for treating a pulmonary artery disease comprising the steps of: Providing a recycled polyester material; performing a physical regeneration operation including physically regenerating a portion of the recycled polyester material and pelletizing the portion of the recycled polyester material to obtain a physical recycled polyester chip having a first intrinsic viscosity; performing a chemical regeneration operation including chemically regenerating another portion of the recycled polyester material and granulating another portion of the recycled polyester material to obtain a chemically recycled polyester chip having a second intrinsic viscosity less than the first intrinsic viscosity; Mixing the physical recycled polyester chips and the chemical recycled polyester chips together according to a predetermined intrinsic viscosity; and forming a polyester film having a predetermined intrinsic viscosity by melt extruding the blended physically recycled polyester chips and chemically recycled polyester chips. The polyester film has a predetermined intrinsic viscosity of 0.45 dL / g to 0.75 dL / g, an acid value of 10 mgKOH / g to 80 mgKOH / g, a surface roughness (Ra) of 1 nm to 100 nm, and a friction coefficient of 0.2 to 0.6.

[0007] In one embodiment, the present invention provides a polyester film having a predetermined intrinsic viscosity by mixing, melting, and extruding a physically recycled polyester resin and a chemically recycled polyester resin according to a predetermined intrinsic viscosity. The predetermined intrinsic viscosity of the polyester film is 0.45 dL / g to 0.75 dL / g. The acid value of the polyester film is 10 mgKOH / g to 80 mgKOH / g, the surface roughness of the polyester film is 1 nm to 100 nm, and the friction coefficient of the polyester film is 0.2 to 0.6.

[0008] According to one embodiment of the present invention, the content of isophthalic acid in the polyester film is 0.5 mol% to 5 mol% based on 100 mol% of the total amount of the polyester film. The storage modulus of the polyester film measured at 150±2° C. and 10 Hz is 4.0×10 9 dyne / cm 2 ~6.5×10 9 dyne / cm 2 It is.

[0009] According to one embodiment of the present invention, the haze of the polyester film is 5% or less.

[0010] According to one embodiment of the present invention, the content of biomass-derived ethylene glycol in the polyester film is 5 wt% or less, based on 100 wt% of the total amount of the polyester film.

[0011] In order to solve the above technical problems, one of the technical solutions adopted in the present disclosure is to provide a polyester film. In one embodiment, a polyester film is provided. The polyester film has a predetermined intrinsic viscosity of 0.45 dL / g to 0.75 dL / g, an acid value of 10 mgKOH / g to 80 mgKOH / g, a surface roughness of 1 nm to 100 nm, and a friction coefficient of 0.2 to 0.6.

[0012] According to one embodiment of the present invention, the content of isophthalic acid in the polyester film is 0.5 mol% to 5 mol% based on 100 mol% of the total amount of the polyester film. The storage modulus of the polyester film measured at 150±2° C. and 10 Hz is 4.0×10 9 dyne / cm 2 ~6.5×10 9 dyne / cm 2 It is.

[0013] According to one embodiment of the present invention, the haze of the polyester film is 5% or less.

[0014] According to one embodiment of the present invention, the content of biomass-derived ethylene glycol in the polyester film is 5 wt % or less, based on 100 wt % of the total amount of the polyester film. Effect of the Invention

[0015] From the above, in the polyester film and its manufacturing method of the present invention, the technical solution of "performing a physical regeneration operation including physically regenerating a part of the recycled polyester material and granulating a part of the recycled polyester material to obtain a physical recycled polyester chip having a first intrinsic viscosity, performing a chemical regeneration operation including chemically regenerating another part of the recycled polyester material and granulating another part of the recycled polyester material to obtain a chemical recycled polyester chip having a second intrinsic viscosity smaller than the first intrinsic viscosity, and mixing the physical recycled polyester chip and the chemical recycled polyester chip according to a predetermined intrinsic viscosity" can control the overall intrinsic viscosity of the recycled polyester material to be suitable for the production of polyester film. This can effectively increase the proportion of recycled polyester material used in the polyester film, so that the final polyester film product can meet the requirements for environmental protection.

[0016] The features and technical contents of the present disclosure will become apparent from the following detailed description and drawings. However, the drawings provided are for illustrative purposes only and are not intended to be limiting. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic flow chart of a method for producing a polyester film according to one embodiment of the present disclosure.

[0018] [Diagram 2] FIG. 2 is a schematic diagram of the molecular weight distribution of different polyester chip materials according to one embodiment of the present disclosure.

[0019] [Diagram 3] FIG. 3 shows the test results of the storage modulus of a polyester film according to one embodiment of the present disclosure (test conditions: film thickness 100 μm (micrometers), test direction machine direction (MD)).

[0020] [Figure 4] FIG. 4 shows the test results of the storage modulus of a polyester film according to one embodiment of the present disclosure (test conditions: film thickness 100 μm, test direction transverse direction (TD)). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, examples of the present disclosure will be described by specific embodiments. The present disclosure will be apparent to those skilled in the art from the contents disclosed herein. The present disclosure can be implemented or applied by other different specific embodiments. Details of the present specification can be modified or changed in various ways according to various viewpoints and applications without departing from the spirit of the disclosure. In addition, it is noted that the drawings of the present disclosure are schematic drawings and are not drawn according to actual scale. The following description will further describe the technical contents of the present disclosure. However, the contents disclosed herein are not intended to limit the protection scope of the present disclosure.

[0022] In this specification, terms such as "first", "second", "third", etc. may be used to describe various elements or signals, but it is understood that these elements or signals should not be limited by these terms. These terms are mainly used to distinguish one element from another element or one signal from another signal. In addition, the term "or" referred to in this specification may include any and all combinations of one or more of the associated listed items, depending on the actual situation.

[0023] [Manufacturing method of polyester film]

[0024] The present disclosure makes it possible to provide polyester film products that meet environmental protection demands by increasing the proportion of recycled polyester material used in polyester films.

[0025] Referring to Fig. 1, according to one embodiment of the present disclosure, a method for producing a polyester film is provided, which can effectively increase the proportion of recycled polyester material used in the polyester film, and the polyester film thus produced has good processability. The method for producing a polyester film of the present invention includes steps S110 to S150. Note that the order of the steps and the actual operation method described in this embodiment can be adjusted as necessary, and are not limited to those described in this embodiment.

[0026] Step S110 includes providing a recycled polyester material.

[0027] To obtain reusable recycled polyester materials, the method for recycling polyester materials includes collecting various kinds of polyester waste and classifying the polyester waste according to its type, color, and use. The polyester waste is then compressed and baled. The baled polyester waste is then transported to a waste disposal site. In this embodiment, the polyester waste is recycled PET bottles. However, the present disclosure is not limited thereto.

[0028] The method for recycling polyester materials of the present invention further includes removing other objects (e.g., bottle caps, labels, adhesives) on the polyester waste. The polyester waste is then physically and mechanically crushed. The bottle caps, liners, and bottle bodies of different materials are then floated and separated. The crushed polyester waste is then dried to obtain a recycled polyester material product, such as recycled PET (r-PET) bottle flakes, which can facilitate the subsequent film manufacturing process.

[0029] It is noted that in another modified embodiment of the present disclosure, the recycled polyester material may be a processed product of recycled polyester material obtained, for example, by direct purchase.

[0030] It should be noted that the terms "polyester" and "polyester material" referred to herein refer to any type of polyester, particularly aromatic polyesters, and specifically refer herein to polyesters derived from terephthalic acid and ethylene glycol, i.e., polyethylene terephthalate (PET).

[0031] Furthermore, the polyester may be, for example, polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), or polyethylene naphthalate (PET). In this embodiment, the polyester is preferably PTT and PBT. Copolymers may also be used. Copolymers refer in particular to copolymers obtainable from two or more dicarboxylic acids and / or two or more glycol components.

[0032] Step S120 includes performing a physical regeneration operation, including physically regenerating a portion of the recycled polyester material and subjecting it to granulation to obtain a physically recycled polyester chip. The physically recycled polyester chip has a first intrinsic viscosity.

[0033] Specifically, the physical recycling operation involves physically and mechanically grinding a portion of the recycled polyester material (e.g., r-PET bottle flakes) to reduce the time and energy required to melt the recycled polyester material. The ground recycled polyester material is then melted to bring the recycled polyester material into a molten state. The molten recycled polyester material is then filtered through a first screen to remove solid impurities from the recycled polyester material. Finally, the filtered recycled polyester material is extruded and pelletized to form physical recycled polyester chips.

[0034] That is, the recycled polyester material is reshaped by cutting, melting, filtering, and extruding in sequence, thus rearranging the polyester molecules of the original recycled polyester material to produce a plurality of physically recycled polyester chips.

[0035] It should be noted that during physical regeneration, the polyester molecules of the recycled polyester material are only rearranged, not reorganized. Therefore, the components originally contained in the original recycled polyester material (e.g., metal catalysts, lubricants, copolymerization monomers) are still contained in the physical recycled polyester material, and therefore the polyester film as the final product also contains the above-mentioned components. Furthermore, the physically recycled polyester chips also retain the properties of the recycled polyester material itself.

[0036] Since the molecular weight of the recycled polyester material does not change much during physical regeneration, the recycled polyester material in the molten state has a relatively high viscosity and relatively poor flow properties, so if a screen with a too small mesh size is used, the filtration efficiency is likely to decrease.

[0037] In order to improve the filtering performance, in this embodiment, the first screen preferably has a mesh size of 10 μm to 100 μm. That is, the first screen can filter solid impurities having a particle size larger than the mesh size. However, the present disclosure is not limited thereto.

[0038] Specifically, the physically recycled polyester chip obtained by the physical regeneration operation usually has a relatively high intrinsic viscosity (IV). In this embodiment, the physically recycled polyester chip has a first intrinsic viscosity, and the first intrinsic viscosity of the physically recycled polyester chip is usually 0.60 dL / g or more, preferably 0.65 dL / g to 0.90 dL / g, and particularly preferably 0.65 dL / g to 0.80 dL / g.

[0039] The method mainly used in the related art to adjust the intrinsic viscosity of the physically recycled polyester chips is solid-state polymerization. However, the solid-state polymerization method may only be used to increase the intrinsic viscosity of the physically recycled polyester chips, and not to decrease the intrinsic viscosity of the physically recycled polyester chips. In addition, in a general film manufacturing process, the intrinsic viscosity of the polyester chips is usually limited to a certain range. The physically recycled polyester chips manufactured by the physical recycling method are usually only applicable to the bottle blowing process or the spinning process, and cannot be applied to the film manufacturing process.

[0040] In order to solve the above technical problems, in the polyester film manufacturing method provided in one embodiment of the present disclosure, the physical recycling method and the chemical recycling method (also called decomposition polymerization recycling method) may be combined to adjust the overall intrinsic viscosity of the recycled polyester chips. In particular, by reducing the overall intrinsic viscosity of the recycled polyester chips, the recycled polyester chips can be applied to the film manufacturing process. The related technical contents are described as the following steps S130 to S150.

[0041] Step S130 includes performing a chemical regeneration operation, including chemically regenerating another portion of the recycled polyester material and subjecting it to granulation to obtain chemically recycled polyester chips, the chemically recycled polyester chips having a second intrinsic viscosity, the second intrinsic viscosity of the chemically recycled polyester chips being less than the first intrinsic viscosity of the physically recycled polyester chips.

[0042] More specifically, the chemical regeneration operation involves cutting or grinding another portion of the recycled polyester material (e.g., r-PET bottle flakes) to reduce the time and energy consumption required to depolymerize the recycled polyester material. The cut or ground recycled polyester material is then fed into a chemical depolymerization solution to depolymerize the recycled polyester material to form a material mixture. The material mixture is then filtered through a second screen to remove solid impurities from the recycled polyester material, thereby reducing the concentration of non-polyester impurities in the material mixture.

[0043] Next, the material mixture after filtration through the second screen is subjected to an esterification reaction, and an inorganic additive or a copolymerizable compound monomer is added during the esterification reaction. Finally, the monomers and / or oligomers in the material mixture are repolymerized under specific reaction conditions and granulated to obtain chemically recycled polyester chips. The liquid temperature of the chemical depolymerization liquid may be, for example, 160°C to 250°C. However, the present disclosure is not limited thereto. Furthermore, the mesh size of the second screen is smaller than the mesh size of the first screen.

[0044] It is believed that the above chemical depolymerization solution can cause chain scission of polyester molecules in the recycled polyester material, thereby achieving the effect of depolymerization. Furthermore, a polyester composition having a relatively short molecular chain and an ester monomer consisting of one diacid unit and two diol units (e.g., bis(2-hydroxyethyl) terephthalate (BHET)) can be obtained. That is, the material mixture has a smaller molecular weight than the recycled polyester material.

[0045] In this embodiment, the chemical depolymerization liquid may be, for example, a solution of water, methanol, ethanol, ethylene glycol, diethylene glycol, or a combination thereof. However, the present disclosure is not limited thereto. For example, water is used for hydrolysis, and methanol, ethanol, ethylene glycol, diethylene glycol, etc. are used for alcoholysis.

[0046] Furthermore, unlike physical recycling operations, chemical recycling operations include "depolymerization and repolymerization of polyester molecules in recycled polyester materials," and it is noted that the polyester molecules may be depolymerized into molecules having relatively small molecular weights and then repolymerized into new polyester resins.

[0047] In another embodiment of the present disclosure, the chemically recycled polyester chips may be prepared not only by the method described in the above embodiment, but also by a hydrolysis method or a supercritical fluid method. The hydrolysis method is a method in which a recycled polyester material in an alkaline solution is irradiated with microwaves while controlling the temperature and pressure to be constant, thereby completely decomposing the polyester molecules into monomers. The supercritical fluid method is a method in which a recycled polyester material is decomposed into a small amount of monomers and oligomers in methanol in a supercritical fluid state. The yield of monomers and oligomers is affected by the reaction temperature and reaction time.

[0048] Specifically, chemical recycling operations can depolymerize recycled polyester materials into smaller molecular weight monomers, making it easier to filter out impurities (e.g., colloidal impurities and other non-polyester impurities) originally contained in recycled polyester materials (e.g., r-PET bottle flakes) than physical recycling operations.

[0049] In addition, the chemical regeneration operation can reduce the molecular weight of the recycled polyester material (e.g., by forming polyester compositions and compound monomers with relatively short molecular chains), so that the recycled polyester material has a relatively low viscosity and improved flow characteristics after depolymerization. Therefore, the chemical regeneration operation may use a screen with a relatively small mesh size to remove impurities with relatively small particle sizes from the polyester material.

[0050] In order to improve the filtering performance, in this embodiment, the second screen preferably has a mesh size of 1 μm to 10 μm. That is, the second screen can filter solid impurities having a particle size larger than the above mesh size. However, the present disclosure is not limited thereto.

[0051] Regarding the filtration of solid impurities, the physical regeneration operation can only filter out the solid impurities with relatively large particle sizes in the recycled polyester material, while the chemical regeneration operation can filter out the solid impurities with relatively small particle sizes in the recycled polyester material, so that the production quality of the polyester film can be effectively improved.

[0052] Specifically, the chemically recycled polyester chips produced by chemical regeneration operation usually have a relatively low inherent viscosity.Furthermore, the inherent viscosity of the chemically recycled polyester chips can be relatively easily controlled, and the inherent viscosity of the chemically recycled polyester chips can be controlled to be lower than the inherent viscosity of the physically recycled polyester chips.

[0053] In this embodiment, the chemically recycled polyester chip has a second intrinsic viscosity, and the second intrinsic viscosity of the chemically recycled polyester chip is typically 0.65 dL / g or less, preferably 0.40 dL / g to 0.65 dL / g, and particularly preferably 0.50 dL / g to 0.65 dL / g.

[0054] Step S140 includes mixing the physical recycled polyester chips and the chemical recycled polyester chips together according to a predetermined intrinsic viscosity, which is suitable for producing polyester film.

[0055] More specifically, the physical recycled polyester chips and the chemical recycled polyester chips are mixed together in a predetermined weight ratio according to a predetermined intrinsic viscosity, so that the mixed physical recycled polyester chips and the chemical recycled polyester chips have a predetermined intrinsic viscosity and are suitable for producing polyester films.

[0056] Moreover, in this embodiment, there is no need to add virgin polyester chips to the production of polyester film. Therefore, the proportion of recycled polyester material used in polyester film is increased. However, the present disclosure is not limited thereto. If necessary, additional virgin polyester chips can be appropriately added to the physical recycled polyester chips and chemical recycled polyester chips mixed together.

[0057] In this embodiment, the predetermined intrinsic viscosity suitable for producing a polyester film is usually 0.45 dL / g to 0.75 dL / g, preferably 0.50 dL / g to 0.75 dL / g, and particularly preferably 0.55 dL / g to 0.65 dL / g.

[0058] In order to increase the proportion of recycled polyester material used, each of the above-mentioned various recycled polyester chips is used in an appropriate amount.

[0059] From the viewpoint of a predetermined weight ratio, based on 100 parts by weight of all polyester chips used, the amount of the physically recycled polyester chips used is preferably 50 parts by weight to 95 parts by weight, and particularly preferably 60 parts by weight to 80 parts by weight. The amount of the chemically recycled polyester chips used is preferably 5 parts by weight to 50 parts by weight, and particularly preferably 20 parts by weight to 40 parts by weight. However, the present disclosure is not limited thereto.

[0060] That is, in the present embodiment, in terms of the amount of use, the proportion of the physically recycled polyester chips is large, and the proportion of the chemically recycled polyester chips is small. However, the present disclosure is not limited thereto.

[0061] Step S150 includes blending the physically recycled polyester chips and the chemically recycled polyester chips and melt extruding them to form a polyester film, the polyester film having a predetermined intrinsic viscosity.

[0062] In this polyester film, the physically recycled polyester chips are formed into a physically recycled polyester resin, the chemically recycled polyester chips are formed into a chemically recycled polyester resin, and the physically recycled polyester resin and the chemically recycled polyester resin are uniformly mixed with each other.

[0063] According to the mixing ratio in step S140, based on the total amount of polyester film being 100 wt%, the content of the physically recycled polyester resin is preferably 50 wt% to 95 wt%, particularly preferably 60 wt% to 80 wt%, and the content of the chemically recycled polyester resin is preferably 5 wt% to 50 wt%, particularly preferably 20 wt% to 40 wt%.

[0064] Furthermore, the total content of the physically recycled polyester resin and the chemically recycled polyester resin is preferably 55 wt % to 100 wt %, and particularly preferably 70 wt % to 100 wt %.

[0065] It should be noted that "wt%" as used herein is an abbreviation for weight percent.

[0066] According to the above configuration, the polyester film manufacturing method of the present embodiment can use a high proportion of recycled polyester material, and no or only a small amount of virgin polyester chips are required to be added. For example, in one embodiment of the present disclosure, the amount of virgin polyester chips used is usually 50 parts by weight or less, preferably 30 parts by weight or less, and particularly preferably 10 parts by weight or less.

[0067] In one embodiment of the present disclosure, the physically recycled polyester chips have a first acid value and the chemically recycled polyester chips have a second acid value, the second acid value being greater than the first acid value. The first acid value is 10 mg KOH / g to 40 mg KOH / g, and the second acid value is 20 mg KOH / g to 70 mg KOH / g.

[0068] Specifically, referring to FIG. 2, the physically recycled polyester chips have a first molecular weight distribution 1, and the chemically recycled polyester chips have a second molecular weight distribution 2, which has a wider range than the first molecular weight distribution 1.

[0069] By combining the first molecular weight distribution 1 of the physical recycled polyester chips and the second molecular weight distribution 2 of the chemically recycled polyester chips, the physical recycled polyester chips and the chemical recycled polyester chips mixed together have, as a whole, a third molecular weight distribution 3 that is between the ranges of the first molecular weight distribution 1 and the second molecular weight distribution 2.

[0070] Specifically, from the viewpoint of molecular weight distribution, chemically recycled polyester chips have a relatively wide molecular weight distribution, which can improve the productivity of the film manufacturing process. However, polyester films manufactured using only chemically recycled polyester chips may have relatively poor physical properties (e.g., mechanical properties). In addition, the manufacturing cost of chemically recycled polyester chips is relatively high.

[0071] In addition, the physically recycled polyester chips have a relatively narrow molecular weight distribution, which may reduce the productivity of the film manufacturing process. However, the polyester film produced using only the physically recycled polyester chips may have relatively good physical properties. In other words, neither the purely physical recycling method nor the purely chemical recycling method is satisfactory.

[0072] The polyester film manufacturing method of one embodiment of the present disclosure is characterized by improving the productivity of the film-forming process and producing a polyester film having relatively good physical properties by combining physically recycled polyester chips and chemically recycled polyester chips.

[0073] That is, polyester films produced by combining physical and chemical recycling operations have improved quality compared to polyester films produced by only physical or only chemical recycling operations.

[0074] Specifically, the polyester film manufacturing method of the present invention further comprises adding inorganic particles to the recycled polyester material in a physical or chemical recycling operation, and the final polyester film comprises the inorganic particles.

[0075] In this embodiment, the inorganic particles are lubricants. However, the present disclosure is not limited thereto. The lubricant is at least one material selected from the group consisting of silicon dioxide particles, calcium carbonate particles, barium sulfate particles, polystyrene particles, silicone particles, and acrylic particles. Furthermore, the content of the lubricant is 0.01wt% to 10wt% based on the total amount of the polyester film being 100wt%.

[0076] [Polyester film]

[0077] The method for producing the polyester film according to the embodiment of the present disclosure is as described above. Hereinafter, the polyester film according to the embodiment of the present disclosure will be described. In this embodiment, the polyester film is formed by the above-mentioned production method. However, the present disclosure is not limited thereto.

[0078] The polyester film comprises a physically recycled polyester resin and a chemically recycled polyester resin, the chemically recycled polyester resin and the physically recycled polyester resin being mixed together.

[0079] The physically recycled polyester resin is formed from physically recycled polyester chips, the physically recycled polyester chips having a first intrinsic viscosity. The chemically recycled polyester resin is formed from chemically recycled polyester chips, the chemically recycled polyester chips having a second intrinsic viscosity, the second intrinsic viscosity being less than the first intrinsic viscosity.

[0080] By mixing physically recycled polyester chips and chemically recycled polyester chips in a predetermined weight ratio and melt extruding the mixture according to a predetermined intrinsic viscosity, a polyester film having a predetermined intrinsic viscosity can be obtained.

[0081] In an embodiment of the present disclosure, the first intrinsic viscosity of the physically recycled polyester chip is 0.60 dL / g or more, the second intrinsic viscosity of the chemically recycled polyester chip is 0.65 dL / g or less, and the predetermined intrinsic viscosity is 0.45 dL / g to 0.75 dL / g.

[0082] In one embodiment of the present disclosure, the first intrinsic viscosity of the physically recycled polyester chips is 0.60 dL / g to 0.80 dL / g, the second intrinsic viscosity of the chemically recycled polyester chips is 0.50 dL / g to 0.65 dL / g, and the predetermined intrinsic viscosity is 0.60 dL / g to 0.65 dL / g.

[0083] In one embodiment of the present disclosure, the polyester film has an acid value of 10 mgKOH / g to 80 mgKOH / g, and preferably has an acid value of 40 mgKOH / g to 70 mgKOH / g.

[0084] The acid value of the above polyester film is tested with reference to the ASTM D7409-15 standard test method and is measured by titration method.

[0085] When the acid value of the polyester film is 10 mgKOH / g to 80 mgKOH / g, the polyester film exhibits heat resistance and hydrolysis resistance at a low acid value.

[0086] In one embodiment of the present disclosure, the polyester film satisfies the following conditions.

[0087] The content of isophthalic acid in the polyester film is 0.5 mol% to 5 mol% based on 100 mol% (mol % or molar ratio) of the total amount of the polyester film, and the content of biomass-derived ethylene glycol in the polyester film is 5 wt% or less based on 100 wt% of the total amount of the polyester film.

[0088] This polyester film has a haze (cloudiness) of 5% or less, a surface roughness (Ra) of 1 nm to 100 nm, and a friction coefficient of 0.2 to 0.6.

[0089] The friction coefficient of the polyester film is measured based on ASTM D1894.

[0090] If the surface roughness of the polyester film is 1 nm to 100 nm (the surface roughness is measured according to DIN EN ISO 4287 / 4288) and the friction coefficient of the polyester film is 0.2 to 0.6, these parameter conditions facilitate the polyester film production, film recovery, and post-processing procedures.

[0091] In one embodiment of the present disclosure, the storage modulus of the polyester film measured at 150±2° C. and 10 Hz is 4.0×10 9 dyne / cm 2 ~6.5×10 9 dyne / cm 2 and preferably 4.2×10 9 dyne / cm 2 ~6.0×10 9 dyne / cm 2 The storage modulus of the polyester film is an average value of the storage modulus of the polyester film measured in MD and TD using a dynamic viscoelasticity measuring device. Specific measurement results are shown in Figures 3 and 4. However, the present disclosure is not limited thereto.

[0092] In the polyester film and its manufacturing method provided by the present disclosure, the technical solution of "performing a physical regeneration operation including physically regenerating a part of the recycled polyester material and granulating a part of the recycled polyester material to obtain a physically recycled polyester chip having a first intrinsic viscosity, performing a chemical regeneration operation including chemically regenerating another part of the recycled polyester material and granulating another part of the recycled polyester material to obtain a chemically recycled polyester chip having a second intrinsic viscosity smaller than the first intrinsic viscosity, and mixing the physical recycled polyester chip and the chemical recycled polyester chip with each other according to a predetermined intrinsic viscosity" can control the overall intrinsic viscosity of the recycled polyester material to be suitable for the production of polyester film, thereby effectively increasing the proportion of recycled polyester material used in the polyester film, so that the final polyester film product can meet the requirements for environmental protection.

[0093] The above description is only for the preferred and possible embodiments of the present disclosure, and therefore does not limit the scope of the present disclosure. Any equivalent technical modifications made from the specification and drawings of the present disclosure shall be included in the scope of the present disclosure. [Industrial Applicability]

[0094] The polyester film and / or the method for forming the polyester film from the recycled polyester material of the present invention can be applied to the polyester recycling industry. Furthermore, the polyester film from the recycled polyester material of the present invention can be applied to any commercially common item (e.g., magnetic tape, insulating tape, photographic film, tracing film, packaging film, electrical insulating film, engineering paper, etc.). [Explanation of symbols]

[0095] S110, S120, S130, S140, S150 Step 1. First molecular weight distribution 2. Second Molecular Weight Distribution 3. The third molecular weight distribution

Claims

1. Providing a recycled polyester material; conducting a physical regeneration operation, the physical regeneration operation including physically regenerating a portion of the recycled polyester material and pelletizing the portion of the recycled polyester material to obtain a physical recycled polyester chip having a first intrinsic viscosity; performing a chemical regeneration operation, the chemical regeneration operation including chemically regenerating another portion of the recycled polyester material and granulating another portion of the recycled polyester material to obtain a chemically recycled polyester chip having a second intrinsic viscosity less than the first intrinsic viscosity; mixing the physical recycled polyester chips and the chemical recycled polyester chips together according to a predetermined intrinsic viscosity; forming a polyester film having the predetermined intrinsic viscosity by melt extruding the blended physically recycled polyester chips and chemically recycled polyester chips; Equipped with the first intrinsic viscosity is 0.65 dL / g to 0.90 dL / g, the second intrinsic viscosity is 0.40 dL / g to 0.65 dL / g, the predetermined intrinsic viscosity of the polyester film is 0.45 dL / g to 0.75 dL / g, the acid value of the polyester film is 10 mgKOH / g to 80 mgKOH / g, the surface roughness (Ra) of the polyester film is 1 nm to 100 nm, and the friction coefficient of the polyester film is 0.2 to 0.6; A method for producing polyester film.

2. A polyester film having a predetermined intrinsic viscosity, the polyester film being formed by mixing, melting, and extruding a physical recycled polyester chip having a first intrinsic viscosity and a chemical recycled polyester chip having a second intrinsic viscosity smaller than the first intrinsic viscosity according to a predetermined intrinsic viscosity, the polyester film comprising: the first intrinsic viscosity is 0.65 dL / g to 0.90 dL / g, the second intrinsic viscosity is 0.40 dL / g to 0.65 dL / g, the predetermined intrinsic viscosity of the polyester film is 0.45 dL / g to 0.75 dL / g, the acid value of the polyester film is 10 mgKOH / g to 80 mgKOH / g, the surface roughness of the polyester film is 1 nm to 100 nm, and the friction coefficient of the polyester film is 0.2 to 0.6; Polyester film.

3. The content of isophthalic acid in the polyester film is 0.5 mol % to 5 mol % based on 100 mol % of the total amount of the polyester film; The storage modulus of the polyester film measured at 150±2° C. and 10 Hz was 4.0×10 ９ dyne / cm ２ ~6.5 x 10 ９ dyne / cm ２ That is, The polyester film of claim 2.

4. 3. The polyester film of claim 2, wherein the haze of the polyester film is 5% or less.

5. 3. The polyester film of claim 2, wherein the content of the biomass-derived ethylene glycol in the polyester film is 5 wt % or less based on 100 wt % of a total amount of the polyester film.

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