Polyester white film and its manufacturing method

Abstract

The present invention discloses a polyester white film and a manufacturing method thereof, which can have a higher proportion of recycled polyester raw materials. The manufacturing method of the polyester white film comprises the following steps. A recycled polyester material is provided. A portion of the recycled polyester material is physically reprocessed to obtain physically recycled polyester particles, and the physically recycled polyester particles have a first characteristic viscosity. Another portion of the recycled polyester material is chemically reprocessed to obtain chemically recycled polyester particles, and the chemically recycled polyester particles have a second characteristic viscosity, which is less than the first characteristic viscosity. According to a predetermined characteristic viscosity, white recycled polyester particles, physically recycled polyester particles and chemically recycled polyester particles are mixed to form a polyester particle raw material. The polyester particle raw material is melt-extruded to form a polyester white film, and the polyester white film has a predetermined characteristic viscosity.

Description

Technical Field

[0001] The present invention relates to a polyester white film and a manufacturing method thereof, in particular to a polyester white film prepared by using both physically recycled polyester resin and chemically recycled polyester resin and a manufacturing method thereof. Background Art

[0002] In the prior art, the most common recycling method for waste PET bottles is physical recycling (or mechanical recycling). The physical recycling method mainly involves first physically and mechanically crushing the waste PET bottle materials; then, placing the crushed PET bottle materials in a high temperature environment to melt; then, granulating the melted PET bottle materials to form physical recycled polyester pellets. These physical recycled polyester pellets can be used for subsequent processing operations.

[0003] Physically recycled polyester pellets produced by physical recycling methods usually have a higher intrinsic viscosity (IV). To adjust the intrinsic viscosity of physically recycled polyester pellets, the existing technology mainly adopts the method of solid state polymerization. However, the method of solid state polymerization can only be used to increase the intrinsic viscosity of physically recycled polyester pellets, and it cannot be used to reduce the intrinsic viscosity of physically recycled polyester pellets. In addition, the general film-making process usually has certain limitations on the intrinsic viscosity range of polyester pellets. Physically recycled polyester pellets produced by physical recycling methods are usually only suitable for bottle blowing process (bottle blowing process) and spinning process (spinning process), and are not suitable for extrusion film making process (film extrusion).

[0004] If it is necessary to make physically recycled polyester chips suitable for film making, the existing technology mainly reduces the intrinsic viscosity of the polyester material by mixing rationally recycled polyester chips and additional virgin polyester chips. However, this method will not be able to effectively increase the proportion of recycled polyester materials in the polyester white film, so that the polyester white film product finally obtained cannot meet the demands of environmental protection. In other words, there are certain limitations on the proportion of recycled polyester in the existing polyester white film, which needs to be overcome. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a polyester white film and a manufacturing method thereof in view of the deficiencies in the prior art.

[0006] In order to solve the above technical problems, one of the technical solutions adopted by the present invention is to provide a method for manufacturing a polyester white film. The method for manufacturing a polyester white film includes the following steps: providing a recycled polyester material; physically regenerating a portion of the recycled polyester material to obtain physically regenerated polyester chips; wherein the physically regenerated polyester chips have a first characteristic viscosity; chemically regenerating another portion of the recycled polyester material to obtain chemically regenerated polyester chips; wherein the chemically regenerated polyester chips have a second characteristic viscosity, and the second characteristic viscosity is less than the first characteristic viscosity; according to a predetermined characteristic viscosity, mixing white recycled polyester chips, the physically regenerated polyester chips and the chemically regenerated polyester chips to form a polyester chip raw material; melt-extruding the polyester chip raw material to form a polyester white film, wherein the polyester white film has the predetermined characteristic viscosity. The predetermined intrinsic viscosity of the polyester white film is 0.36 dL / g to 0.65 dL / g; the acid value of the polyester white film is 10 mgKOH / g to 80 mgKOH / g; the surface roughness (Ra) of the polyester white film is 1 nm to 500 nm; and the dynamic friction coefficient of the polyester white film is 0.2 to 0.4.

[0007] In order to solve the above technical problems, one of the technical solutions adopted by the present invention is to provide a polyester white film. The polyester white film is formed by mixing, melting and extruding a physical recycled polyester resin and a chemical recycled polyester resin according to a predetermined characteristic viscosity, and the polyester white film has the predetermined characteristic viscosity; wherein the predetermined characteristic viscosity of the polyester white film is 0.36dL / g to 0.65dL / g; the acid value of the polyester white film is 10mgKOH / g to 80mgKOH / g; the surface roughness (Ra) of the polyester white film is 1nm to 500nm; the dynamic friction coefficient of the polyester white film is 0.2 to 0.4.

[0008] In some embodiments, based on the total weight of the polyester white film being 100 mol%, the content of isophthalic acid in the polyester white film is between 0.1 mol% and 6 mol%; the storage modulus of the polyester white film at 150°C and 10 Hz is between 3.5×109dyne / cm2 and 6.0×109dyne / cm2.

[0009] In some embodiments, the haze of the polyester white film is greater than 80%, the light transmittance of the polyester white film is less than 10%, the reflectivity of the polyester white film is 80% to 98%, and the shading value of the polyester white film is greater than or equal to 1.2.

[0010] In order to solve the above technical problems, another technical solution adopted by the present invention is to provide a polyester white film. The predetermined intrinsic viscosity of the polyester white film is 0.36 dL / g to 0.65 dL / g; the acid value of the polyester white film is 10 mgKOH / g to 80 mgKOH / g; the surface roughness (Ra) of the polyester white film is 1 nm to 500 nm; and the dynamic friction coefficient of the polyester white film is 0.2 to 0.4.

[0011] In some embodiments, based on the total weight of the polyester white film being 100 mol%, the content of isophthalic acid in the polyester white film is between 0.1 mol% and 6 mol%; the storage modulus of the polyester white film at 150°C and 10 Hz is 3.5×109dyne / cm2 to 6.0×109dyne / cm2.

[0012] In some embodiments, the haze of the polyester white film is greater than 80%, the light transmittance of the polyester white film is less than 10%; the reflectivity of the polyester white film is 80% to 98%; and the shading value of the polyester white film is greater than or equal to 1.2.

[0013] In some embodiments, based on the total weight of the polyester white film being 100 weight percent, the content of biomass-derived ethylene glycol in the polyester white film is no more than 5 weight percent.

[0014] One of the beneficial effects of the present invention is that the polyester white film and the manufacturing method thereof provided by the present invention can adjust the polyester pellet raw material to have a predetermined characteristic viscosity through the technical scheme of "mixing white recycled polyester pellets, the physically recycled polyester pellets and the chemically recycled polyester pellets according to a predetermined characteristic viscosity to form a polyester pellet raw material", and can be suitable for an extrusion film forming process and has a higher proportion of recycled polyester raw materials.

[0015] To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only for reference and description and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the present invention and together with the description serve to explain the principles of the present invention.

[0017] Figure 1 The schematic diagram is a process flow diagram of the method for manufacturing the polyester white film of the present invention;

[0018] Figure 2Schematic diagram of molecular weight distribution of polyester pellet raw material of the present invention;

[0019] Figure 3 The test result of the storage modulus of the polyester white film in one embodiment of the present invention;

[0020] Figure 4 The figure is the test result of the storage modulus of the polyester white film according to another embodiment of the present invention.

[0021] Description of Reference Numerals

[0022] 1: first molecular weight distribution;

[0023] 2: Second molecular weight distribution;

[0024] 3: The third molecular weight distribution. DETAILED DESCRIPTION

[0025] The following is an explanation of the implementation methods of the "polyester white film and its manufacturing method" disclosed in the present invention through specific embodiments. Those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed in various ways based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are only simple schematic illustrations and are not depicted according to actual dimensions. It is stated in advance. The following embodiments will further explain the relevant technical contents of the present invention in detail, but the disclosed contents are not intended to limit the scope of protection of the present invention. In addition, the term "or" used in this article may include any one or more combinations of the associated listed items depending on the actual situation.

[0026] [Production method of polyester white film]

[0027] One of the purposes of the present invention is to increase the proportion of recycled polyester materials used in polyester white film, so that the polyester white film product can meet the demands of environmental protection.

[0028] To achieve this, see Figure 1 As shown, according to one embodiment of the present invention, a method for manufacturing a polyester white film is provided, which can effectively increase the proportion of recycled polyester material in the polyester white film and make the obtained polyester white film have good processability. The method for manufacturing the polyester white film includes steps S110 to S150. It must be noted that the order of the steps and the actual operation method described in this embodiment can be adjusted according to needs and are not limited to those described in this embodiment.

[0029] The step S110 includes: providing recycled polyester material.

[0030] In order to obtain reusable recycled polyester materials, the polyester material recycling method includes: collecting various types of waste polyester materials; and classifying the waste polyester materials according to their types, colors, and uses. Then, compressing and packaging the waste polyester materials. Then, transporting the packaged waste polyester materials to a waste treatment plant. In this embodiment, the waste polyester materials are recycled PET bottles (r-PET), but the present invention is not limited thereto.

[0031] The polyester material recycling method further comprises: removing other objects (such as bottle caps, labels, and adhesives) from the waste polyester materials. Then, physically and mechanically crushing the waste polyester materials. Then, using flotation to separate the bottle mouth, liner, and bottle body of different materials. Then, drying the crushed waste polyester materials to obtain processed recycled polyester materials, such as recycled PET bottle flakes, to facilitate the subsequent film manufacturing process.

[0032] It is worth mentioning that in other variations of the present invention, the recycled polyester material may also be, for example, directly purchased processed recycled polyester material.

[0033] It should be noted that the terms "polyester", "polyester material" and the like in this article refer to any type of polyester, especially aromatic polyester, and here particularly refer to polyester formed by copolymerization of terephthalic acid and ethylene glycol, namely polyethylene terephthalate (PET).

[0034] Furthermore, the polyester may be, for example, polytrimethyleneterephthalate (PTT), polybutyleneterephthalate (PBT) or polyethylenenaphthalate (PEN). In this embodiment, the polyester is preferably polyethyleneterephthalate and polytrimethyleneterephthalate. In addition, copolymers may be used, which specifically refer to copolymers obtained by using two or more dicarboxylic acids and / or two or more diol components.

[0035] In one embodiment of the present invention, the recycled PET bottle flakes contain isophthalic acid (IPA) as a diacid unit, and therefore, the polyester white film finally formed also contains isophthalic acid. Wherein, based on the total weight of the polyester white film being 100 mol%, the content of isophthalic acid in the polyester white film is between 0.1 mol% and 6 mol%. Preferably, the content of isophthalic acid in the polyester white film is between 0.5 mol% and 5 mol%.

[0036] In one embodiment of the present invention, the recycled PET bottle flakes contain biomass-derived ethylene glycol as a glycol unit, and therefore, the final formed polyester white film also contains the biomass-derived ethylene glycol. Wherein, based on the total weight of the polyester white film being 100 weight percent, the content of the biomass-derived ethylene glycol in the polyester white film is not greater than 5 weight percent. Furthermore, based on all the carbon in the polyester white film, the radioactive element (C 14 ) has a carbon content of no more than 5% derived from biomass as measured.

[0037] In one embodiment of the present invention, the recycled PET bottle flakes contain a metal catalyst, so that the polyester white film formed in the end also contains the metal catalyst. The metal catalyst is at least one selected from the group consisting of antimony (Sb), germanium (Ge), and titanium (Ti). Based on the total weight of the polyester white film being 100 weight percent, the content of the metal catalyst in the polyester white film is 0.0003 weight percent to 0.04 weight percent.

[0038] The step S120 comprises: physically regenerating a portion of the recycled polyester material to obtain physically regenerated polyester chips. The physically regenerated polyester chips have a first intrinsic viscosity. In this embodiment, the first intrinsic viscosity of the physically regenerated polyester chips is generally not less than 0.60 dL / g. Preferably, the first intrinsic viscosity is 0.65 dL / g to 0.90 dL / g. More preferably, the first intrinsic viscosity is 0.65 dL / g to 0.80 dL / g.

[0039] Specifically, the manufacturing steps of physical recycled polyester pellets include: physically and mechanically crushing a portion of the recycled polyester material (such as recycled PET bottle flakes) to reduce the time and energy consumption required for melting the recycled polyester material. Then, the crushed recycled polyester material is melted by a single-screw extruder or a twin-screw extruder to make the recycled polyester material in a molten state. Then, the recycled polyester material in a molten state is filtered by a first screen to remove solid impurities in the recycled polyester material. Finally, granulation is performed to form the physical recycled polyester pellets.

[0040] That is to say, the recycled polyester material is reshaped through the steps of cutting, melting, filtering, and extrusion in sequence, so that the polyester molecules in the original recycled polyester material are rearranged to obtain a plurality of the physically recycled polyester particles.

[0041] It is worth mentioning that, since the polyester molecules of the recycled polyester material are only rearranged but not reorganized during the physical reprocessing process, the components originally present in the recycled polyester material (such as metal catalysts, lubricants, or copolymer monomers, etc.) will still exist in the physical recycled polyester pellets, so that the polyester white film finally formed also contains these components. Furthermore, the various properties of the recycled polyester material itself will also be retained in the physical recycled polyester pellets.

[0042] Since the molecular weight of the recycled polyester material does not change much during the physical reprocessing process, the viscosity of the recycled polyester material in the molten state is relatively high and its flow properties are relatively poor. Therefore, if a screen with too small a mesh size is used, it will easily lead to poor filtration efficiency.

[0043] In order to achieve a better filtering effect, in this embodiment, the mesh size of the first screen is preferably between 50 microns and 100 microns. In other words, the first screen can screen out solid impurities with a particle size larger than the mesh size, but the present invention is not limited thereto.

[0044] It is worth noting that different film-making processes have different applicable intrinsic viscosity ranges. Generally speaking, physically recycled polyester pellets (physically recycled polyester resins) obtained through physical reprocessing will have a higher intrinsic viscosity (not less than 0.60dL / g). If only physically recycled polyester pellets (physically recycled polyester resins) are used, the polyester pellet raw materials are only suitable for bottle blowing and spinning processes, but not for extrusion film-forming processes.

[0045] To adjust the intrinsic viscosity of physical recycled polyester pellets, the existing technology mainly adopts the solid state polymerization method. However, the solid state polymerization method can only be used to increase the intrinsic viscosity of physical recycled polyester pellets, and it cannot be used to reduce the intrinsic viscosity of physical recycled polyester pellets.

[0046] In order to solve the above problems, the present invention obtains chemically recycled polyester pellets (chemically recycled polyester resin) through a chemical reprocessing step in step S130, which has a lower intrinsic viscosity (not greater than 0.65 dL / g). In this way, by using both physical recycled polyester pellets and chemical recycled polyester pellets and adjusting the usage ratio of physical recycled polyester pellets and chemical recycled polyester pellets, the intrinsic viscosity of the polyester pellet raw material can be adjusted, so that the polyester pellet raw material can be suitable for the extrusion film forming process.

[0047] The step S130 includes: chemically regenerating another portion of the recycled polyester to obtain chemically regenerated polyester chips. The chemically regenerated polyester chips have a second intrinsic viscosity, and the second intrinsic viscosity of the chemically regenerated polyester chips is less than the first intrinsic viscosity of the physically regenerated polyester chips. In this embodiment, the second intrinsic viscosity of the chemically regenerated polyester chips is generally not greater than 0.65 dL / g. Preferably, the second intrinsic viscosity is 0.40 dL / g to 0.65 dL / g. More preferably, the second intrinsic viscosity is 0.50 dL / g to 0.65 dL / g.

[0048] Specifically, the manufacturing steps of chemically recycled polyester pellets include: cutting or crushing another portion of the recycled polyester material (such as recycled PET bottle flakes) to reduce the time and energy consumption required for depolymerizing the recycled polyester material. Then, placing the cut or crushed recycled polyester material into a chemical depolymerization liquid to depolymerize the recycled polyester material to form a raw material mixture. Then, filtering the raw material mixture with a second screen to remove solid impurities in the recycled polyester material, thereby reducing the concentration of non-polyester impurities in the raw material mixture.

[0049] Next, the raw material mixture filtered by the second screen is subjected to an esterification reaction, and an inorganic additive or a copolymer compound monomer is added during the esterification reaction. Finally, under specific reaction conditions, the monomers and / or oligomers in the raw material mixture are repolymerized and granulated to obtain the chemically regenerated polyester granules. The liquid temperature of the chemical depolymerization liquid may be, for example, 160° C. to 250° C., but the present invention is not limited thereto. Furthermore, a mesh hole diameter of the second screen is smaller than a mesh hole diameter of the first screen.

[0050] It is worth mentioning that the chemical depolymerization liquid can break the polyester molecules in the recycled polyester material, thereby achieving the depolymerization effect, and can further obtain polyester compositions with shorter molecular chains and ester monomers composed of a diacid unit and two diol units, such as bis(2-Hydroxyethyl)terephthalate (BHET). In other words, the molecular weight of the raw material mixture is less than the molecular weight of the recycled polyester material.

[0051] In this embodiment, the chemical depolymerization liquid can be, for example, a solution of water, methanol, ethanol, ethylene glycol, diethylene glycol, or a combination thereof, but the present invention is not limited thereto. For example, water is used for hydrolysis, and methanol, ethanol, ethylene glycol, or diethylene glycol is used for alcoholysis.

[0052] In addition, it is worth mentioning that, unlike the physical reprocessing step, the chemical reprocessing step involves "depolymerization and repolymerization of polyester molecules in recycled polyester materials", which can depolymerize polyester molecules into molecules with smaller molecular weight and further repolymerize them into new polyester resins.

[0053] In other embodiments of the present invention, the preparation method of chemically recycled polyester particles is not limited to the above embodiments, and can also be prepared by hydrolysis or supercritical fluid method. The hydrolysis method is to make the recycled polyester material in an alkaline solution, by adjusting a certain temperature and pressure, and under the irradiation of microwave radiation, the polyester molecules are completely cracked into monomers. The supercritical fluid method is to make the recycled polyester material decompose into a small amount of monomers and oligomers in methanol in a supercritical fluid state. Among them, the yield of monomers and oligomers will be affected by the reaction temperature and reaction time.

[0054] Furthermore, since the chemical recycling method can depolymerize the recycled polyester material into monomers with small molecular weight, the impurities (such as colloidal impurities or other non-polyester impurities) originally present in the recycled polyester material (such as recycled PET bottle flakes) can be removed more easily by filtering compared to the physical recycling method.

[0055] Furthermore, since the chemical reprocessing process can reduce the molecular weight of the recycled polyester material (e.g., forming polyester components and compound monomers with shorter molecular chains), the viscosity of the recycled polyester material after depolymerization is relatively low and its flow properties are better. Accordingly, the chemical reprocessing process can use a screen with a smaller mesh size to remove impurities with smaller particle sizes in the polyester material.

[0056] In order to achieve a better filtering effect, in this embodiment, the mesh size of the second screen is preferably between 10 microns and 50 microns. In other words, the second screen can screen out solid impurities with a particle size larger than the mesh size, but the present invention is not limited thereto.

[0057] In terms of filtering solid impurities, the physical reprocessing step can only filter solid impurities with larger particle sizes in the recycled polyester material, while the chemical reprocessing step can filter solid impurities with smaller particle sizes in the recycled polyester material. Thus, the production quality of the polyester white film can be effectively improved.

[0058] Furthermore, the chemically recycled polyester pellets produced by the chemical reprocessing step generally have a lower intrinsic viscosity. Furthermore, the intrinsic viscosity of the chemically recycled polyester pellets is easier to control, and the intrinsic viscosity of the chemically recycled polyester pellets can be controlled to be lower than the intrinsic viscosity of the physical and chemically recycled polyester pellets.

[0059] The step S140 includes: mixing white recycled polyester pellets, physical recycled polyester pellets, and chemical recycled polyester pellets according to a predetermined intrinsic viscosity to form a polyester pellet raw material.

[0060] The intrinsic viscosity of the polyester pellet raw material is suitable for the film-making process. Specifically, the intrinsic viscosity of the polyester pellet raw material is 0.48 dL / g to 0.8 dL / g; preferably, the intrinsic viscosity of the polyester pellet raw material is 0.50 dL / g to 0.60 dL / g. The predetermined intrinsic viscosity is 0.36 dL / g to 0.65 dL / g; preferably, the predetermined intrinsic viscosity is 0.40 dL / g to 0.60 dL / g.

[0061] More specifically, the white recycled polyester pellets, the physical recycled polyester pellets and the chemical recycled polyester pellets are mixed with each other at a predetermined weight ratio according to the predetermined intrinsic viscosity. Thus, the mixed white recycled polyester pellets, the physical recycled polyester pellets and the chemical recycled polyester pellets can have the predetermined intrinsic viscosity and are suitable for use in the manufacture of polyester white film.

[0062] The white recycled polyester particles contain white additives, which are selected from the group consisting of calcium carbonate particles, barium sulfate particles and titanium dioxide particles. The particle size of the white additives is between 0.1 microns and 20 microns.

[0063] In this embodiment, it can be selected whether to add multiple white additives to the white recycled polyester pellets according to the purpose of the polyester white film. In a preferred embodiment, the white recycled polyester pellets have a single type of white additive.

[0064] For example, when calcium carbonate particles or barium sulfate particles are used as white additives, polyester white film can have good reflective effect (reflectivity 80% to 98%) and low specific gravity, and can usually be used for posters or express labels. However, since the surface of polyester white film has micropores, it is not suitable for long-term outdoor use.

[0065] For example, when titanium dioxide particles are used as a white additive, the polyester white film can have a lower color difference value (△E) and stronger physical properties, so it is more suitable for outdoor use. Further, the titanium dioxide can be anatase titanium dioxide or rutile titanium dioxide. When the polyester white film does not need to be exposed outdoors for a long time, anatase titanium dioxide or rutile titanium dioxide can be used; when the polyester white film may need to be exposed outdoors for a long time, rutile titanium dioxide can be used.

[0066] The white recycled polyester pellets can be obtained through a physical reprocessing step or a chemical reprocessing step. In other words, the white recycled polyester pellets include at least one of physical white recycled polyester pellets and chemical white recycled polyester pellets. The intrinsic viscosity of the white recycled polyester pellets is 0.35 dL / g to 0.70 dL / g, and preferably, the intrinsic viscosity of the white recycled polyester pellets is 0.4 dL / g to 0.65 dL / g.

[0067] Specifically, the manufacturing method of the physical white recycled polyester pellets includes: melting a portion of the recycled polyester material to obtain a first molten mixture. Adding a white additive to the first molten mixture to form a second molten mixture. Reshaping the second molten mixture to obtain the physical white recycled polyester pellets. Based on the total weight of the physical white recycled polyester pellets being 100 weight percent, the physical white recycled polyester pellets include 5 weight percent to 60 weight percent of the white additive.

[0068] For example, when the white additive is calcium carbonate particles or barium sulfate particles, based on the total weight of the physical white recycled polyester particles being 100 weight percent, the physical white recycled polyester particles include 20 weight percent to 35 weight percent of the white additive. When the white additive is titanium dioxide particles, based on the total weight of the physical white recycled polyester particles being 100 weight percent, the physical white recycled polyester particles include 5 weight percent to 15 weight percent of the white additive.

[0069] Specifically, the manufacturing method of the chemical white recycled polyester pellets includes: depolymerizing another part of the recycled polyester material to obtain a first oligomer mixture. Adding a white additive to the first oligomer mixture to form a second oligomer mixture. Repolymerizing the second oligomer mixture to obtain the chemical white recycled polyester pellets. Based on the total weight of the chemical white recycled polyester pellets being 100 weight percent, the chemical white recycled polyester pellets include 20 weight percent to 40 weight percent of the white additive.

[0070] For example, when the white additive is calcium carbonate particles or barium sulfate particles, based on 100 weight percent of the total weight of the chemically white recycled polyester pellets, the chemically white recycled polyester pellets include 20 weight percent to 35 weight percent of the white additive.

[0071] In order to increase the utilization ratio of recycled polyester materials, the above-mentioned various recycled polyester pellets all have suitable usage ranges.

[0072] In terms of the predetermined weight ratio, based on 100 parts by weight of the polyester pellet raw material (i.e., all polyester pellets), the amount of physically recycled polyester pellets is preferably 50 to 95 parts by weight, preferably 60 to 80 parts by weight. The amount of chemically recycled polyester pellets is between 5 to 50 parts by weight, preferably 20 to 40 parts by weight, but the present invention is not limited thereto.

[0073] In a preferred embodiment, the amount of physically recycled polyester particles is higher than that of chemically recycled polyester particles, but the present invention is not limited thereto.

[0074] The step S150 comprises: melt-extruding the polyester pellet raw material to form a white polyester film, wherein the white polyester film has a predetermined intrinsic viscosity.

[0075] In the polyester white film, the physical recycled polyester particles (including the physical white recycled polyester particles) are formed into the physical recycled polyester resin, and the chemical recycled polyester particles (including the chemical white recycled polyester particles) are formed into the chemical recycled polyester resin. Moreover, the white additive in the white recycled polyester particles is evenly dispersed in the physical recycled polyester resin and the chemical recycled polyester resin.

[0076] According to the mixing ratio in step S140, based on the total weight of the polyester white film being 100 weight percent, the content of the physical recycled polyester resin is preferably 50 weight percent to 95 weight percent, and particularly preferably 60 weight percent to 80 weight percent. The content of the chemical recycled polyester resin is preferably 5 weight percent to 50 weight percent, and particularly preferably 20 weight percent to 40 weight percent. The content of the white additive is 0.1 weight percent to 40 weight percent.

[0077] Furthermore, the total content of the physical recycled polyester resin and the chemical recycled polyester resin is 55 weight percent (wt%) to 100 weight percent, and the preferred total content is 70 weight percent to 100 weight percent.

[0078] According to the above configuration, the polyester white film manufacturing method of this embodiment can be made by using a high proportion of recycled polyester materials, which does not require the addition of additional virgin polyester masterbatch (virgin polyester resin), or only requires the addition of a small amount of virgin polyester masterbatch. For example, in one embodiment of the present invention, the amount of virgin polyester masterbatch is usually not more than 50 weight parts, preferably, the virgin polyester masterbatch is not more than 30 weight parts, and more preferably, the virgin polyester masterbatch is not more than 10 weight parts.

[0079] In one embodiment of the present invention, the physically recycled polyester pellets have a first acid value, and the chemically recycled polyester pellets have a second acid value, and the second acid value is greater than the first acid value. The first acid value is between 10 mgKOH / g and 40 mgKOH / g, and the second acid value is between 20 mgKOH / g and 70 mgKOH / g.

[0080] For further information, see Figure 2 As shown, the physical recycled polyester particles have a first molecular weight distribution 1, the chemical recycled polyester particles have a second molecular weight distribution 2, and the distribution range of the second molecular weight distribution 2 is wider than the distribution range of the first molecular weight distribution 1.

[0081] In addition, by mixing and matching the physical recycled polyester pellets and the chemical recycled polyester pellets, the polyester pellet raw materials (white recycled polyester pellets, physical recycled polyester pellets and chemical recycled polyester pellets) have a third molecular weight distribution 3, and the distribution range of the third molecular weight distribution 3 is between the first molecular weight distribution 1 and the second molecular weight distribution 2.

[0082] Furthermore, in terms of molecular weight distribution, chemically recycled polyester pellets have a wider molecular weight distribution, which can help the productivity of the film-making process, but the physical properties of polyester white film produced solely using chemically recycled polyester pellets will be poor (such as mechanical properties). In addition, the production cost of chemically recycled polyester pellets is relatively high.

[0083] The molecular weight distribution of physical recycled polyester pellets is relatively narrow, and its productivity in film-making process is poor, but it can produce polyester white film with stronger mechanical properties and better physical properties. In other words, it is not an ideal method to use only physical recycled polyester pellets or chemical recycled polyester pellets.

[0084] The characteristic of the method for manufacturing the polyester white film of the embodiment of the present invention is that the physical recycled polyester particles and the chemical recycled polyester particles are used simultaneously, which can improve the productivity of the film-making process, improve the physical properties of the polyester white film, and reduce the production cost of the polyester white film.

[0085] In addition, the method for manufacturing the polyester white film further comprises adding inorganic particles to the recycled polyester material in a physical or chemical reprocessing step, so that the finally obtained polyester white film contains the inorganic particles.

[0086] In this embodiment, the inorganic particles are slipping agents, but the present invention is not limited thereto. The slipping agent is at least one selected from a material group consisting of silicon dioxide particles, calcium carbonate particles, barium sulfate particles, polystyrene particles, silica gel particles, and acrylic particles. Furthermore, based on the total weight of the polyester white film being 100 weight percent, the content of the slipping agent is between 0.1 weight percent and 10 weight percent.

[0087] [Polyester white film]

[0088] The above is a method for manufacturing a polyester white film according to an embodiment of the present invention. The polyester white film according to an embodiment of the present invention is described below. In this embodiment, the polyester white film is formed by the above manufacturing method, but the present invention is not limited thereto.

[0089] The material of the polyester white film includes a physical recycled polyester resin, a chemical recycled polyester resin and a white additive. The physical recycled polyester resin is formed by physically recycled polyester particles, and the physically recycled polyester particles have a first characteristic viscosity. The chemical recycled polyester resin is formed by chemically recycled polyester particles, and the chemically recycled polyester particles have a second characteristic viscosity, and the second characteristic viscosity is less than the first characteristic viscosity. The white additive is dispersed between the chemically recycled polyester resin and the physically recycled polyester resin.

[0090] It is worth noting that the physical recycled polyester particles and the chemical recycled polyester particles are mixed according to a predetermined intrinsic viscosity, so that the obtained polyester white film can have a predetermined intrinsic viscosity.

[0091] In one embodiment of the present invention, the first intrinsic viscosity of the physically recycled polyester particles is not less than 0.60 dL / g, the second intrinsic viscosity of the chemically recycled polyester particles is not greater than 0.65 dL / g, and the predetermined intrinsic viscosity is 0.36 dL / g to 0.65 dL / g.

[0092] In a preferred embodiment of the present invention, the first characteristic viscosity of the physically recycled polyester particles is 0.65 dL / g to 0.80 dL / g, the second characteristic viscosity of the chemically recycled polyester particles is 0.50 dL / g to 0.65 dL / g, and the predetermined characteristic viscosity is 0.60 dL / g to 0.65 dL / g.

[0093] Furthermore, the acid value of the polyester white film of the present invention ranges from 10 mgKOH / g to 100 mgKOH / g. Preferably, the acid value of the polyester white film of the present invention ranges from 10 mgKOH / g to 80 mgKOH / g. More preferably, the acid value of the polyester white film of the present invention ranges from 40 mgKOH / g to 70 mgKOH / g. The acid value of the polyester white film is measured according to the standard measurement method D7409-15 set by the American Society for Testing and Materials (ASTM). When the acid value of the polyester white film is between 10 mgKOH / g and 100 mgKOH / g, the polyester white film has heat resistance and hydrolysis resistance.

[0094] The surface roughness (Ra) of the polyester white film of the present invention is 1 nm to 500 nm. Preferably, the surface roughness of the polyester white film is 10 nm to 450 nm. More preferably, the surface roughness of the polyester white film is 20 nm to 430 nm. The surface roughness of the polyester white film is measured according to DIN EN ISO4287 / 4288.

[0095] The dynamic friction coefficient of the polyester white film of the present invention is 0.2 to 0.4. The dynamic friction coefficient of the polyester white film is measured according to ASTM D1894.

[0096] When the surface roughness of the polyester white film is 1 nm to 500 nm and the dynamic friction coefficient of the polyester white film is 0.2 to 0.4, it is more conducive to the manufacturing, film collection and back-end processing procedures of the polyester white film.

[0097] The storage modulus of the polyester white film of the present invention at 150°C and 10 Hz is 3.5×10 9 dyne / cm 2 Up to 6.0×10 9dyne / cm 2 Preferably, the storage modulus of the polyester white film at 150°C and 10 Hz is 4.0×10 9 dyne / cm 2 Up to 5.0×10 9 dyne / cm 2 The storage modulus of polyester white film is the average value of the storage modulus of polyester white film in the longitudinal direction and width measured by a dynamic viscoelasticity measuring device. For specific measurement results, please refer to Figure 3 and Figure 4 shown.

[0098] It is also worth mentioning that the aforementioned multiple physically recycled polyester pellets and multiple chemically recycled polyester pellets are all obtained by recycling and reusing the recycled polyester material and granulating the recycled polyester material. The recycled polyester material is recycled PET bottle flakes.

[0099] In one embodiment of the present invention, the polyester white film has the following characteristics. Based on the total weight of the polyester white film being 100 molar percentage concentration, the content of isophthalic acid in the polyester white film is between 0.1 molar percentage concentration and 6 molar percentage concentration. Based on the total weight of the polyester white film being 100 weight percentage concentration, the content of biomass-derived ethylene glycol in the polyester white film is not more than 5 weight percentage concentration. The light shielding value of the polyester white film is greater than or equal to 1.2. The light transmittance of the polyester white film is not greater than 10%, preferably, the light transmittance of the polyester white film is not greater than 5%. The surface roughness (Ra) of the polyester white film is 10 nanometers to 200 nanometers. The reflectivity of the polyester white film is 80% to 98%. The color difference value (△E) of the polyester white film is less than or equal to 10, preferably, the color difference value (△E) of the polyester white film is less than or equal to 2. The dynamic friction coefficient of the polyester white film is 0.2 to 0.4.

[0100] [Beneficial Effects of Embodiments]

[0101] One of the beneficial effects of the present invention is that the polyester white film and the manufacturing method thereof provided by the present invention can adjust the polyester pellet raw material to have a predetermined characteristic viscosity through the technical scheme of "mixing white recycled polyester pellets, the physically recycled polyester pellets and the chemically recycled polyester pellets according to a predetermined characteristic viscosity to form a polyester pellet raw material", and can be suitable for an extrusion film forming process and has a higher proportion of recycled polyester raw materials.

[0102] The contents disclosed above are only preferred feasible embodiments of the present invention, and are not intended to limit the scope of the claims of the present invention. Therefore, all equivalent technical changes made using the description and drawings of the present invention are included in the scope of the claims of the present invention.

Claims

1. A method for producing a polyester white film, characterized in that: include: Providing recycled polyester materials; Physically reprocessing a portion of the recycled polyester material to obtain physically recycled polyester pellets; wherein the physically recycled polyester pellets have a first intrinsic viscosity, and the first intrinsic viscosity is 0.65 dL / g to 0.90 dL / g; Chemically reprocessing another portion of the recycled polyester material to obtain chemically recycled polyester pellets; wherein the chemically recycled polyester pellets have a second intrinsic viscosity, the second intrinsic viscosity is 0.40 dL / g to 0.65 dL / g, and the second intrinsic viscosity is less than the first intrinsic viscosity; According to a predetermined intrinsic viscosity, the white recycled polyester pellets, the physically recycled polyester pellets and the chemically recycled polyester pellets are mixed to form a polyester pellet raw material; and Melting and extruding the polyester pellet raw material to form a polyester white film, wherein the polyester white film has the predetermined intrinsic viscosity; The predetermined intrinsic viscosity of the polyester white film is 0.36 dL / g to 0.65 dL / g; the acid value of the polyester white film is 10 mgKOH / g to 80 mgKOH / g; the surface roughness (Ra) of the polyester white film is 1 nm to 500 nm; the dynamic friction coefficient of the polyester white film is 0.2 to 0.4, Wherein, the white recycled polyester particles include at least one of physical white recycled polyester particles and chemical white recycled polyester particles, and the white recycled polyester particles contain white additives, and the white additives are selected from the group consisting of: calcium carbonate particles, barium sulfate particles and titanium dioxide particles; when the white additives are the calcium carbonate particles or the barium sulfate particles, based on the total weight of the physical white recycled polyester particles or the chemical white recycled polyester particles being 100 weight percent, the white additives are 20 to 35 weight percent; when the white additives are the titanium dioxide particles, based on the total weight of the physical white recycled polyester particles being 100 weight percent, the white additives are 5 to 15 weight percent, Wherein, based on 100 parts by weight of the polyester pellet raw material, the amount of the physically recycled polyester pellet is 60 to 80 parts by weight, and the amount of the chemically recycled polyester pellet is 20 to 40 parts by weight.

2. A polyester white film, characterized in that: The polyester pellet raw material is formed by mixing white recycled polyester pellets, physical recycled polyester pellets and chemical recycled polyester pellets according to a predetermined intrinsic viscosity, and then melted and extruded to form the polyester white film having the predetermined intrinsic viscosity; The physically recycled polyester particles have a first intrinsic viscosity, which is 0.65 dL / g to 0.90 dL / g; the chemically recycled polyester particles have a second intrinsic viscosity, which is 0.40 dL / g to 0.65 dL / g; the second intrinsic viscosity is less than the first intrinsic viscosity. The predetermined intrinsic viscosity of the polyester white film is 0.36 dL / g to 0.65 dL / g; the acid value of the polyester white film is 10 mgKOH / g to 80 mgKOH / g; the surface roughness (Ra) of the polyester white film is 1 nm to 500 nm; the dynamic friction coefficient of the polyester white film is 0.2 to 0.4, Wherein, the white recycled polyester particles include at least one of physical white recycled polyester particles and chemical white recycled polyester particles, and the white recycled polyester particles contain white additives, and the white additives are selected from the group consisting of: calcium carbonate particles, barium sulfate particles and titanium dioxide particles; when the white additives are the calcium carbonate particles or the barium sulfate particles, based on the total weight of the physical white recycled polyester particles or the chemical white recycled polyester particles being 100 weight percent, the white additives are 20 to 35 weight percent; when the white additives are the titanium dioxide particles, based on the total weight of the physical white recycled polyester particles being 100 weight percent, the white additives are 5 to 15 weight percent, Wherein, based on 100 parts by weight of the polyester pellet raw material, the amount of the physically recycled polyester pellet is 60 to 80 parts by weight, and the amount of the chemically recycled polyester pellet is 20 to 40 parts by weight.

3. The polyester white film according to claim 2, characterized in that: Based on the total weight of the polyester white film being 100 mol%, the content of isophthalic acid in the polyester white film is between 0.1 mol% and 6 mol%; the storage modulus of the polyester white film at 150°C and 10 Hz is 3.5×10 9 dyne / cm 2 Up to 6.0×10 9 dyne / cm 2 .

4. The polyester white film according to claim 2, characterized in that: The haze of the polyester white film is greater than 80%, the light transmittance of the polyester white film is less than 10%, the reflectivity of the polyester white film is 80% to 98%, and the shading value of the polyester white film is greater than or equal to 1.

2.

5. The polyester white film according to claim 2, characterized in that: Based on the total weight of the polyester white film being 100 weight percent, the content of biomass-derived ethylene glycol in the polyester white film is no more than 5 weight percent.

Images