Regenerated polyethylene composition and regenerated film using same

Abstract

The present invention relates to a regenerated polyethylene composite composition and a regenerated film using the same. Specifically, the present invention relates to a regenerated polyethylene composite composition in which polyethylene recovered from a secondary battery separator is used as a raw material, and a regenerated membrane using the regenerated polyethylene composite composition. According to the present invention, a separator on which a coating layer containing an organic binder and / or inorganic particles is formed can be directly reused as a regenerated raw material without a pretreatment process, and a composition for manufacturing a film can be provided.

Description

Technical Field

[0001] The invention relates to a recycled polyethylene composite composition and a recycled film using the recycled polyethylene composite composition. Background Art

[0002] As the use of secondary batteries becomes more widespread, the number of secondary batteries discarded at the end of their life is also increasing. Therefore, various methods for recycling discarded secondary batteries are being studied. For example, by recycling waste secondary batteries and performing pre-processing operations including discharge, crushing, and screening processes, the outer can, separator, and negative / positive electrode can be sorted, and metals such as cobalt, nickel, lithium, and manganese can be recovered.

[0003] However, most of the waste separators recovered from the waste secondary batteries, the waste separators recovered from defective products, or the separator waste generated in the manufacturing process cannot be regenerated and are treated by inappropriate methods such as incineration, and thus are pointed out as the cause of resource waste and environmental pollution.

[0004] Therefore, in order to solve the above-mentioned problems, various efforts are being made to recycle the waste separators, but the physical properties or processability of the waste separators themselves are insufficient, and therefore they need to be adjusted to be suitable for the purpose and molding method of recycling. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] According to one aspect of the present invention, a recycled polyethylene composite composition including polyethylene recovered from a secondary battery separator and used for manufacturing a recycled film may be provided.

[0007] According to another aspect of the present invention, a recycled film can be provided that recycles polyethylene recovered from a secondary battery separator as a raw material. In addition, a recycled polyethylene composite composition can be provided, wherein the polyethylene recovered from the secondary battery separator can be directly used as a recycled polyethylene raw material without a separate pretreatment process such as removing a coating.

[0008] According to another aspect of the present invention, a recycled film can be provided which does not generate defects such as pinholes even when polyethylene recovered from a secondary battery separator is used as a raw material to produce the recycled film.

[0009] (II) Technical solution

[0010] The recycled polyethylene composite composition according to the present invention comprises recycled polyethylene recovered from a separator of a secondary battery and porous powder. As an embodiment, the recycled polyethylene composite composition can be obtained by dry mixing or melting the recycled polyethylene and the porous powder.

[0011] As an embodiment, the recycled polyethylene may be a powder obtained by directly pulverizing a separator or a pellet obtained by melt-extrusion without going through a process of removing a coating layer from the separator.

[0012] As an embodiment, the content of the inorganic particles in the recycled polyethylene may be 70 wt % or less, and is not limited thereto.

[0013] As an embodiment, the total inorganic content of the recycled polyethylene composite composition including the inorganic particles contained in the recycled polyethylene and the porous powder may be 50 wt % or less, and is not limited thereto.

[0014] As an embodiment, the melt flow index of the recycled polyethylene measured at 2.16 kg and 190° C. may be 5 g / 10 min or less, and the density of the recycled polyethylene may be 0.95 g / cm 3 As mentioned above, the weight average molecular weight of the recycled polyethylene may be 50,000 g / mol or more, and is not limited thereto.

[0015] As an embodiment, the recycled polyethylene may contain a low molecular weight substance, which decomposes and shows a peak at a lower temperature than a polyethylene standard substance in the result of measurement using a thermogravimetric analyzer (TGA). The low molecular weight substance refers to a substance measured according to the following measurement method. The thermogravimetric analyzer (TGA) measurement method is measured according to the following measurement method. As an embodiment, a lower temperature than the polyethylene standard substance can be a peak at 200-400°C.

[0016] As an embodiment, the low molecular weight substance may be derived from a coating binder for the separator.

[0017] As an embodiment, in the total weight of the recycled polyethylene, the content of the low molecular weight substance may be 3 wt % or less. The content of the low molecular weight substance may be calculated by the following method.

[0018] As an embodiment, the weight average molecular weight of the low molecular weight substance may be 5000 g / mol or less. The weight average molecular weight may be measured according to the following measurement method.

[0019] As an embodiment, the porous powder may be mixed in a content of 5 wt % or less, and is not limited thereto.

[0020] As an embodiment, the average particle size of the porous powder may be 1-10 μm, and is not limited thereto.

[0021] As an embodiment, the oil absorption of the porous powder may be 50-150 cc / 100 g, and is not limited thereto.

[0022] As an embodiment, the pore volume of the porous powder may be 0.1-1.0 ml / g, and is not limited thereto.

[0023] As an embodiment, the porous powder may be any one selected from porous silica, porous zeolite, porous alumina, etc., or a mixture of two or more thereof.

[0024] Another embodiment of the present invention provides a recycled film, wherein the recycled film comprises the recycled polyethylene composite composition according to one embodiment above, and the number of pinholes is 1 / m 2 the following.

[0025] As an embodiment, the recycled polyethylene composite composition may be prepared by pre-mixing recycled polyethylene recovered from a separator of a secondary battery and a powdered porous powder. As an embodiment, the pre-mixing may be dry mixing or melting.

[0026] As an embodiment, the recycled film may further comprise a virgin polyolefin-based resin.

[0027] As an embodiment, the recycled film may include 60-90 wt % of the recycled polyethylene composite composition and 10-40 wt % of a virgin polyolefin-based resin, and is not limited thereto.

[0028] As an embodiment, the thickness of the regenerated film may be 10-200 μm, and is not limited thereto.

[0029] Another embodiment of the present invention provides a method for manufacturing a recycled membrane, the manufacturing method comprising the following steps: premixing recycled polyethylene recovered from a secondary battery separator and a porous powder to prepare a recycled polyethylene composite composition; and melt-extruding the recycled polyethylene composite composition and a virgin polyolefin-based resin to manufacture a membrane.

[0030] As an embodiment, the step of manufacturing a film may include the following steps: melt-extruding the recycled polyethylene composite composition and the virgin polyolefin-based resin to prepare pellets or preparing a mixture by dry blending; and melt-extruding the pellets or the mixture to manufacture a film.

[0031] As an embodiment, the premix may be selected from the following (i) to (iii).

[0032] (i) A method of dry mixing powdered or granular recycled polyethylene and powdered porous powder;

[0033] (ii) a method in which powdered or granular recycled polyethylene and powdered porous powder are quantitatively added into a batch mixer at one time and mixed; and

[0034] (iii) A method comprising the steps of metering the porous powder in powder form through a side feeder of an extruder and mixing it with recycled polyethylene in powder form or granular form.

[0035] As an embodiment, the recycled polyethylene may be a powder obtained by directly pulverizing a separator or a pellet obtained by melt-extrusion without going through a process of removing a coating layer from the separator.

[0036] (III) Beneficial effects

[0037] The recycled polyethylene composite composition according to one embodiment of the present invention includes polyethylene recovered from a secondary battery separator and can be reused as a raw material for manufacturing a film even if it includes a coating composition and inorganic particles used in manufacturing a separator.

[0038] Furthermore, the recycled film using the recycled polyethylene composite composition as a raw material can prevent the occurrence of defects such as pinholes.

[0039] The regenerated membrane according to one embodiment of the present invention can be applied to various membrane fields such as a separator for secondary batteries and a garbage bag for recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a graph showing TGA analysis results of recycled polyethylene recovered from a separator of a secondary battery according to one embodiment of the present invention.

[0041] Figure 2 : is a graph showing the TGA analysis results of the recycled polyethylene composite composition according to one embodiment of the present invention.

[0042] Figure 3 This is a diagram showing the state in which pinholes are generated when a regenerated film is produced according to Comparative Example 1. DETAILED DESCRIPTION

[0043] The present invention will be described in detail below, but this is merely exemplary, and the present invention is not limited to the specific embodiments described exemplarily.

[0044] In addition, unless otherwise defined, all technical terms and scientific terms have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used in the description of the present invention are only used to effectively describe specific embodiments and are not intended to limit the present invention.

[0045] Furthermore, unless otherwise specifically stated, singular forms used in the specification and claims may also include plural forms.

[0046] Furthermore, unless otherwise specifically described to the contrary, when a part is described as “including” or “comprising” a certain component, this means that other components may also be included, rather than excluding other components.

[0047] In addition, unless specifically defined otherwise, when a layer or component is described as being “on” another layer or component, this includes not only a case where one layer or component is in contact with another layer or component but also a case where another layer or component exists between the two layers or components.

[0048] In addition, "about," "substantially," and the like are used in the sense of a value or near a value to account for the tolerances for preparation and materials inherent in the referenced values, and to prevent unscrupulous infringers from taking unfair advantage of disclosures that refer to exact or absolute values ​​in order to aid in the understanding of the invention.

[0049] In one embodiment of the present invention, "recycled polyethylene" refers to polyethylene recovered from secondary battery separators, and refers to a powder obtained by crushing any one or more of the separators selected from separators separated and recovered by disassembling waste secondary batteries, separators recovered from defective secondary battery products, waste materials generated when manufacturing secondary battery separators, separator ends recovered after trimming, etc., or a material processed into granules by melt extrusion. Although not limited, the melt extrusion temperature when processed into the granules can be 200-250°C.

[0050] In one embodiment of the present invention, "low molecular weight substances" refer to substances that show a peak at a lower temperature than the main peak when analyzing the polyethylene raw material recovered from the secondary battery separator using a thermogravimetric analyzer (TGA) compared with a graph of virgin polyethylene with a weight average molecular weight of 50,000 g / mol to 2,000,000 g / mol as a standard substance. For example, Figure 1 As shown, the low molecular weight substance refers to a substance showing a peak at a lower temperature of 200-400°C than the main peak of 400-600°C. In addition, the standard substance refers to a virgin polyethylene resin that is not made into a separator, and may be a virgin polyethylene resin having the same or similar weight average molecular weight as recycled polyethylene recovered from a separator of a secondary battery. The content of the low molecular weight substance can be calculated according to the following method.

[0051] In one embodiment of the present invention, "pinhole" refers to Figure 3 The defects found in the manufactured film are shown as the circled portion in FIG. The shape of the pinhole is not limited and may be circular or elliptical. The pinhole may be a portion formed thinner than the average thickness of the film or a portion forming a hole. For example, the pinhole may be a defect having a diameter of 1 mm or more, a defect having a diameter of 1-10 mm, and a defect having a diameter larger or smaller than the above range. The diameter is the minimum length in the shape of the pinhole. That is, as Figure 3 As shown, in the case of an elliptical pinhole having a narrow width and a long length, the diameter refers to the diameter of the narrow width.

[0052] Hereinafter, the present invention will be described in more detail.

[0053] One embodiment of the present invention provides a recycled polyethylene composite composition obtained by mixing recycled polyethylene recovered from a separator of a secondary battery and a porous powder.

[0054] The present inventors have studied the use of recycled polyethylene recovered from the separator of a secondary battery as a raw material to produce a recycled film. When the recycled polyethylene is used as a raw material to produce a recycled film, it is confirmed that the following Figure 3 Defects such as pin holes shown.

[0055] In order to solve the above problem, the results of measuring the recycled polyethylene using a thermogravimetric analyzer (TGA) are compared with the graph of measuring the virgin polyethylene having the same molecular weight as the polyethylene of the recycled secondary battery separator, as shown in FIG. Figure 1 As shown, it was confirmed that a peak was additionally found at 200-400° C. The substance found in this peak was called a low molecular weight substance, and the origin of this low molecular weight substance was predicted.

[0056] Generally, the secondary battery separator is a microporous film composed of polyethylene resin, and a ceramic layer is formed on one or both sides of the microporous film, and the inorganic particles of the ceramic layer are bound and fixed by a binder. It is expected that the low molecular weight substances are derived from the binder used in the ceramic layer.

[0057] In order to manufacture the film, the film is processed at a temperature higher than or equal to the melting point of polyethylene as a raw material, at which temperature the low molecular weight substances are expected to gasify, thereby causing defects such as pinholes on the surface of the film. When pinholes are generated, the appearance and physical properties of the film are reduced, and thus it is judged as defective.

[0058] Therefore, as a result of research to eliminate the problems caused by low molecular weight substances in recycled polyethylene recovered from secondary battery separators, it was found that problems such as pinholes can be solved when a composite composition is prepared by mixing porous powders, thereby completing the present invention.

[0059] Hereinafter, each configuration of the present invention will be described in more detail.

[0060] [Recycled polyethylene composite composition]

[0061] The recycled polyethylene composite composition according to one embodiment of the present invention is formed by mixing recycled polyethylene recovered from the separator of a secondary battery and porous powder. At this time, the mixing may be that the porous powder is mixed with the recycled polyethylene in a powder form. By mixing in a powder form, the film defects targeted in the present invention can be eliminated.

[0062] The mixing method is not limited, but can be dry mixing or mixing in an extruder or the like. For example, it can be a method of dry mixing powdered or granular recycled polyethylene and powdered porous powder, a method of quantitatively adding powdered or granular recycled polyethylene and powdered porous powder to an intermittent mixer at one time, or adding powdered or granular recycled polyethylene through the feeder of the extruder, and then quantitatively adding powdered porous powder through the side feeder and mixing. The conditions during the mixing are not limited, but when mixing using an extruder, it can be above 150°C, above 160°C, above 170°C, above 180°C, above 190°C, above 200°C, below 300°C, below 290°C, below 280°C, below 270°C, below 260°C, below 250°C, and can be any value between the above values. For example, it can be carried out in the range of 150-300°C, 170-250°C, 170-230°C, and 170-210°C. When the mixing is performed within the above range, the generation of carbides can be reduced and low molecular weight substances in the separator can be effectively removed, but the invention is not limited thereto.

[0063] [Recycled polyethylene recovered from separators of secondary batteries]

[0064] The separator of a secondary battery generally comprises a microporous membrane composed of a polyethylene resin and a ceramic coating, wherein inorganic particles of the ceramic coating are bonded and fixed to one or both sides of the microporous membrane by an adhesive. Alternatively, an adhesive layer containing organic adhesive particles is formed as required to improve adhesion to the electrode.

[0065] As for the recycled polyethylene according to one embodiment of the present invention, only the microporous membrane composed of the polyethylene resin can be separated from the separators having various laminated structures as described above and used as a raw material, and the separator including the ceramic coating or adhesive layer can be directly used as a raw material.

[0066] In one embodiment of the present invention, the recycled polyethylene can be prepared and used by directly crushing the separator without removing the coating from the separator or by melt-extruding the granular raw material. Therefore, in addition to the polyethylene resin, the recycled polyethylene according to one embodiment of the present invention can also contain various substances, such as inorganic particles and adhesives.

[0067] The recycled polyethylene including the various substances may satisfy the following physical properties.

[0068] As an embodiment, the molecular weight of the recycled polyethylene is not limited as long as it is the molecular weight of the polyethylene of the microporous membrane used as a porous substrate in the diaphragm. For example, the weight average molecular weight (Mw) can be 50,000 g / mol or more, 100,000 g / mol or more, 150,000 g / mol or more, 200,000 g / mol or more, 250,000 g / mol or more, 300,000 g / mol or more, 400,000 g / mol or more, 500,000 g / mol or more, 600,000 g / mol or more, 650,000 g / mol or more, 700,000 g / mol or more, 800,000 g / mol or more, 900,000 g / mol or more, 3,000,000 g / mol or less, 2,000,000 g / mol or less, 1,500,000 g / mol or less, 1,000,000 g / mol or less, and can be any value between the above numerical values. For example, the weight average molecular weight can be 50,000 g / mol to 3,000,000 g / mol, 50,000 g / mol to 2,000,000 g / mol, 80,000 g / mol to 1,500,000 g / mol, 100,000 g / mol to 1,000,000 g / mol, 100,000 g / mol to 500,000 g / mol, 100,000 g / mol to 300,000 g / mol, 150,000 g / mol to 250,000 g / mol, and is not limited thereto. The weight average molecular weight can be measured by the following measuring method.

[0069] For example, the number average molecular weight (Mn) can be more than 20,000 g / mol, more than 30,000 g / mol, more than 40,000 g / mol, more than 50,000 g / mol, less than 1,000,000 g / mol, less than 800,000 g / mol, less than 500,000 g / mol, less than 300,000 g / mol, and can be any value between the above numerical values. For example, the number average molecular weight can be 20,000 g / mol to 1,000,000 g / mol, 30,000 g / mol to 800,000 g / mol, 30,000 g / mol to 500,000 g / mol, 30,000 g / mol to 300,000 g / mol, 30,000 g / mol to 100,000 g / mol, and is not limited thereto. The number average molecular weight can be measured by the following measurement method.

[0070] In addition, according to ASTM D1238, the melt flow index of the recycled polyethylene measured at 190° C. and 2.16 kg may be 5 g / 10 min or less, 4 g / 10 min or less, 3 g / 10 min or less, 2 g / 10 min or less, 1 g / 10 min or less, 0.01 g / 10 min or more, 0.02 g / 10 min or more, 0.03 g / 10 min or more, 0.04 g / 10 min or more, 0.05 g / 10 min or more, 0.06 g / 10 min or more, The amount of the aqueous phase is 0.04 g / 10 min or more, 0.06 g / 10 min or more, 0.08 g / 10 min or more, 0.09 g / 10 min or more, 0.1 g / 10 min or more, 0.2 g / 10 min or more, 0.3 g / 10 min or more, 0.4 g / 10 min or more, 0.5 g / 10 min or more, 0.6 g / 10 min or more, 0.7 g / 10 min or more, 0.8 g / 10 min or more, 0.9 g / 10 min or more, and can be any value between the above values. For example, the melt flow index can be 0.01-5 g / 10 minutes, 0.01-4 g / 10 minutes, 0.01-3 g / 10 minutes, 0.01-2 g / 10 minutes, 0.01-1 g / 10 minutes, 0.01-0.9 g / 10 minutes, 0.01-0.5 g / 10 minutes, 0.01-3 g / 10 minutes, 0.01-2 g / 10 minutes, 0.01-1 g / 10 minutes.

[0071] In addition, the content of the inorganic particles in the recycled polyethylene can be 70% by weight or less, 50% by weight or less, 30% by weight or less, 25% by weight or less, 1% by weight or more, 2% by weight or more, 3% by weight or more, 4% by weight or more, 5% by weight or more, 6% by weight or more, 7% by weight or more, 8% by weight or more, 9% by weight or more, 10% by weight or more, 15% by weight or more, 20% by weight or more, and can be any value between the above ranges. For example, the content of the inorganic particles can be 1-70% by weight, 2-50% by weight, 3-30% by weight, 5-30% by weight, 10-30% by weight, 15-30% by weight, 20-25% by weight, and is not limited thereto. The content of the inorganic particles is the content determined when the diaphragm is manufactured, and a melt flow index that can be formed by melt extrusion can be provided within the above range, but is not limited thereto. The inorganic particles may be contained in a ceramic coating or a microporous membrane itself.

[0072] In addition, the density of the recycled polyethylene measured according to ASTM D792 may be 0.95 g / cm 3 Above, 1.0g / cm 3 Above, 1.1g / cm 3 Above, 1.2g / cm 3 Above, 1.3g / cm 3Above, 1.4g / cm 3 Above, 1.5g / cm 3 For example, the density may be 0.95-1.5 g / cm 3 , 0.95-1.3g / cm 3 , 0.95-1.2g / cm 3 1.0-1.2g / cm 3 1.0-1.2g / cm 3 .

[0073] In addition, the melting point (Tm) of the recycled polyethylene may be 100°C or more, 110°C or more, 120°C or more, 130°C or more, 140°C or more, 250°C or less, 240°C or less, 230°C or less, 220°C or less, 210°C or less, 200°C or less, 180°C or less, 170°C or less, 160°C or less, 150°C or less, and may be any value between the above values. For example, the melting point may be 100-250°C, 110-230°C, 120-200°C, 120-180°C, 120-160°C, 120-150°C, and is not limited thereto. The melting point may be measured according to the following method.

[0074] Although not limited, when the recycled polyethylene satisfies the above range, it can be molded by melt extrusion to produce a recycled film, which is more preferable.

[0075] As an embodiment, in the gross weight of the recycled polyethylene, the content of the low molecular weight substance of the recycled polyethylene may be 3% by weight or less, 2% by weight or less, 1% by weight or less, or any value between the above values, and is not limited thereto. The content of the low molecular weight substance may be obtained by calculating the area value of the low molecular weight substance having a molecular weight of 5000 g / mol or less in the calibration curve of gel permeation chromatography (GPC). Alternatively, the weight loss ratio near 200-400°C may be measured in thermogravimetric analysis (TGA) data, and the proportion of the low molecular weight substance may be calculated by comparing it with the weight of the entire sample.

[0076] As an embodiment, the weight average molecular weight of the low molecular weight substances contained in the recycled polyethylene can be in a lower range compared to the weight average molecular weight of the polyethylene microporous membrane as the porous substrate of the diaphragm. For example, the weight average molecular weight of the low molecular weight substances contained in the recycled polyethylene can be 5000g / mol or less, 4500g / mol or less, 4000g / mol or less, 3500g / mol or less, 3000g / mol or less, 100g / mol or more, 500g / mol or more, 600g / mol or more, 700g / mol or more, 800g / mol or more, 900g / mol or more, 1000g / mol or more, and can be any value between the above numerical values. For example, the weight average molecular weight of the low molecular weight substances contained in the recycled polyethylene may be 500-5000 g / mol, 1000-5000 g / mol, 1000-4500 g / mol, 1000-4000 g / mol, 1000-3000 g / mol, and is not limited thereto. The weight average molecular weight of the low molecular weight substances may be measured according to the following specific method.

[0077] [Porous powder]

[0078] In one embodiment of the present invention, the porous powder may be a powdered porous particle. For example, the porous powder may be any one or a mixture of two or more selected from porous silica, porous zeolite, and porous alumina, and is not limited thereto. In addition, in the present invention, the powdered porous particle refers to a powdered porous particle that is different from the inorganic particles contained in the separator of the secondary battery and is added separately.

[0079] As an embodiment, in the recycled polyethylene composite composition, the content of the porous powder can be less than 5% by weight, less than 4% by weight, less than 3% by weight, more than 2% by weight, and can be any value between the above values. For example, the porous powder can be used in a content of 2-5% by weight, 3-5% by weight, and within the above range, the film has excellent formability and can be sufficient to prevent defects from occurring in the film. When the content of the added porous powder is too much, the viscosity increases, so the load of the extruder when the film is extruded may increase, and the productivity when the film is manufactured may decrease. In addition, the aggregation phenomenon of the porous powder occurs, so the quality of the film surface may decrease.

[0080] In addition, the total inorganic content of the inorganic particles and the porous powder contained in the recycled polyethylene composite composition can be 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 28% by weight or less, 10% by weight or more, 15% by weight or more, 20% by weight or more, 22% by weight or more, and can be any value between the above values. For example, the total inorganic content can be 10-50% by weight, 15-45% by weight, 20-40% by weight, 22-30% by weight. Although not limited to this, it can have excellent film formability within the above range.

[0081] As an embodiment, the porous powder may have an average particle size of 1-10 μm, an oil absorption of 50-150 ml / 100 g, and a pore volume of 0.1-1.0 ml / g. Within the above range, the effect of reducing the generation of pinholes caused by low molecular weight substances of recycled polyethylene recovered from the separator of a secondary battery according to an embodiment of the present invention is excellent, so it may be preferred, but is not limited thereto.

[0082] As an embodiment, the average particle size of the porous powder may be 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, and may be any value between the above values. For example, the average particle size of the porous powder may be 1-10 μm, 1-9 μm, 1-8 μm, 1-7 μm, 2-6 μm, and is not limited thereto. The average particle size may be measured according to the following measurement method.

[0083] As an embodiment, the oil absorption of the porous powder can be 50 ml / 100g or more, 60 ml / 100g or more, 70 ml / 100g or more, 80 ml / 100g or more, 90 ml / 100g or more, 95 ml / 100g or more, 150 ml / 100g or less, 140 ml / 100g or less, 135 ml / 100g or less, 130 ml / 100g or less, 120 ml / 100g or less, 110 ml / 100g or less, 100 ml / 100g or less, and can be any value between the above values. For example, the oil absorption of the porous powder can be 50-150 ml / 100g, 60-150 ml / 100g, 70-150 ml / 100g, 80-140 ml / 100g, 90-135 ml / 100g, and is not limited thereto. The oil absorption amount can be measured according to the following measurement method.

[0084] As an embodiment, the pore volume of the porous powder may be 0.1 ml / g or more, 0.2 ml / g or more, 0.3 ml / g or more, 0.4 ml / g or more, 0.5 ml / g or more, 1.0 ml / g or less, 0.9 ml / g or less, 0.8 ml / g or less, 0.7 ml / g or less, 0.6 ml / g or less, and may be any value between the above values. For example, the pore volume of the porous powder may be 0.1-1.0 ml / g, 0.2-0.8 ml / g, 0.3-0.7 ml / g, 0.4-0.6 ml / g, and is not limited thereto. The pore volume may be measured according to the following measurement method.

[0085] As an embodiment, the pH of the porous powder may be 4 or more, 5 or more, 8 or less, 7.5 or less, 7 or less, 6 or less, and may be any value between the above values. For example, the pH of the porous powder may be 4 to 8, and is not limited thereto. The pH may be measured according to the following measurement method.

[0086] As an embodiment, the moisture content of the porous powder according to the Loss-on-Drying Method (LOD) can be 5 wt % or less, 4 wt % or less, 3.5 wt % or less, 3 wt % or less, 2 wt % or less, 1.8 wt % or less, and the lower limit is not limited, but can be 0.1 wt % or more. In addition, the moisture content can be any value between the above values. For example, the moisture content can be 0.1-5 wt %, 0.1-4 wt %, 0.1-3.5 wt %, and is not limited thereto. The moisture content can be measured according to the following measurement method.

[0087] As an embodiment, the porous powder is preferably mixed with the recycled polyethylene in a powder form, and the target effect of removing defects such as pinholes can be achieved. Although it is not excluded to mix the porous powder with the polyethylene resin to prepare a masterbatch for addition, in the present invention, when the porous powder is mixed with the recycled polyethylene in a powder form for premixing, low molecular weight substances of the recycled polyethylene can be better removed.

[0088] [Regenerated film and method for producing the same]

[0089] One embodiment of the present invention provides a recycled film manufactured using the recycled polyethylene composite composition.

[0090] As an embodiment, a regenerated membrane is provided, wherein the number of pinholes in the regenerated membrane is 1 / m 2 or substantially no pinholes are formed, that is, the number of pinholes is 0 / m 2For example, the number of pinholes can be 0-1 / m 2 , 0.01-1 / m 2 , 0.05-1 / m 2 , 0.1-1 / m 2 , 0.2-1 / m 2 , 0.3-1 / m 2 The pinhole can be measured according to the following measurement method.

[0091] As an embodiment, the composition for making a film may include the recycled polyethylene composite composition alone.As an embodiment, the composition for making a film may include the recycled polyethylene composite composition and a virgin polyolefin-based resin.

[0092] The virgin polyolefin-based resin refers to a new product that has never been used, and may be selected from polyethylene, polypropylene, and the like.

[0093] The physical properties of the virgin polyolefin-based resin can be adjusted and used according to the physical properties of the recycled film to be produced, so the physical properties of the virgin polyolefin-based resin are not limited. For example, the virgin polyolefin-based resin can be a polyethylene resin.

[0094] As an embodiment, the composition for making a film may include 60-90% by weight of a recycled polyethylene composite composition and 10-40% by weight of a virgin polyolefin-based resin. In addition, the composition for making a film may include 70-80% by weight of a recycled polyethylene composite composition and 20-30% by weight of a virgin polyolefin-based resin. Within the above content range, a recycled film having excellent processability and excellent mechanical and physical properties can be manufactured, but the mixing ratio may vary according to the physical properties of the mixed virgin polyolefin-based resin, and is therefore not limited thereto.

[0095] As an embodiment, the composition for making a film can further include additives such as inorganic particles, anti-blocking agents, ultraviolet blockers and pigments commonly used when making a film as needed, and is not limited thereto. The content of the additive can be less than 5% by weight, less than 4% by weight, less than 3% by weight, less than 2% by weight, more than 0.1% by weight, more than 0.2% by weight, more than 0.5% by weight, and can be any value between the above values. For example, the content of the additive can be 0.1-5% by weight, 0.2-4% by weight, and is not limited thereto.

[0096] As an embodiment, the thickness of the regenerated film can be 10 μm or more, 20 μm or more, 30 μm or more, 200 μm or less, 180 μm or less, 150 μm or less, 130 μm or less, 120 μm or less, 100 μm or less, 80 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, and can be any value between the above values. For example, the thickness of the regenerated film can be 10-200 μm, 20-100 μm, 30-80 μm, and is not limited thereto. The thickness of the film can be measured using a thickness gauge (TELCLOCKCOPORATION, PG-02).

[0097] Next, a method for producing a regenerated membrane according to one embodiment of the present invention will be described.

[0098] A method for manufacturing a recycled membrane according to one embodiment of the present invention comprises the following steps: premixing recycled polyethylene recovered from a separator of a secondary battery and a powdered porous powder to prepare a recycled polyethylene composite composition; and melt-extruding the recycled polyethylene composite composition and a virgin polyolefin-based resin to manufacture a membrane.

[0099] As an embodiment, the recycled polyethylene composite composition can be prepared by premixing recycled polyethylene recovered from a separator of a secondary battery and a powdered porous powder. The premixing can be performed using not only an extruder but also a reactor generally used for preparing a composite composition.

[0100] For example, the premixing may be prepared by a method selected from the following (i) to (iii), but is not limited thereto.

[0101] (i) A method of dry mixing powdered or granular recycled polyethylene and powdered porous powder;

[0102] (ii) a method in which powdered or granular recycled polyethylene and powdered porous powder are quantitatively added into a batch mixer at one time and mixed; and

[0103] (iii) A method comprising the steps of metering the porous powder in powder form through a side feeder of an extruder and mixing it with recycled polyethylene in powder form or granular form.

[0104] As an embodiment, although the temperature conditions during the mixing are not limited, when the mixing is performed using an extruder, the temperature conditions may be 150°C or more, 160°C or more, 170°C or more, 180°C or more, 190°C or more, 200°C or more, 300°C or less, 290°C or less, 280°C or less, 270°C or less, 260°C or less, 250°C or less, and may be any value between the above values. For example, the mixing may be performed within the range of 150-300°C, 170-250°C, 170-230°C, 170-210°C. When the mixing is performed within the above range, the generation of carbides may be reduced, and low molecular weight substances in the diaphragm may be effectively removed, but are not limited thereto.

[0105] As an embodiment, a film is manufactured by melt-extruding the recycled polyethylene composite composition and the virgin polyolefin-based resin. At this time, the recycled polyethylene composite composition and the virgin polyolefin-based resin can be melt-extruded to prepare particles or a mixture can be prepared by dry mixing; the particles or the mixture can be melt-extruded to manufacture a film. When preparing the particles, the melting temperature is not limited, but can be above 150°C, above 160°C, above 170°C, above 180°C, above 190°C, above 200°C, below 300°C, below 290°C, below 280°C, below 270°C, below 260°C, below 250°C, and can be any value between the above values. For example, the preparation of the particles can be carried out in the range of 150-300°C, 170-250°C, 170-230°C, 170-210°C.

[0106] In addition, when the film is manufactured by the melt extrusion, the melt temperature is not limited, but can be 150°C or more, 160°C or more, 170°C or more, 180°C or more, 190°C or more, 200°C or more, 300°C or less, 290°C or less, 280°C or less, 270°C or less, 260°C or less, 250°C or less, and can be any value between the above values. For example, the film can be manufactured in the range of 150-300°C, 170-250°C, 180-230°C, 180-210°C, 180-200°C.

[0107] As an embodiment, the step of manufacturing the film can be performed by using a blow molding machine, or by forming the film into a sheet through a T-die and then performing uniaxial or biaxial stretching.

[0108] The embodiments of the present invention are further described below with reference to specific experimental examples. The embodiments and comparative examples included in the experimental examples are only used to illustrate the present invention and are not used to limit the scope of rights. Various changes and modifications can be made to the embodiments within the scope of the scope and technical ideas of the present invention, which is obvious to those skilled in the art, and such variations and modifications also belong to the scope of rights.

[0109] The following physical properties were evaluated as follows.

[0110] 1) The presence and content of low molecular weight substances

[0111] The measurement was performed using TGA (TA Instruments / TGA Q500 product).

[0112] According to the TGA crucible (Pan) container, prepare about 10 mg of sample.

[0113] Place the prepared sample in the TGA Auto Sampler, select the desired temperature range, heating rate, and reactive gas for analysis. Raise the temperature from room temperature to 900°C at 10°C / min, and switch from N2 gas atmosphere to air atmosphere at 700°C.

[0114] Experimental temperature range: room temperature to 900℃ / 700℃ air change (N2->Air)

[0115] Atmosphere: N2

[0116] Heating rate: 10℃ / min

[0117] Furthermore, the content of low molecular weight substances having a weight average molecular weight of 5000 g / mol or less can be confirmed by confirming the weight loss ratio around 200-400° C. in TGA data and calculating the ratio of the low molecular weight substances in the total weight.

[0118] 2) Whether pinholes are generated

[0119] The produced film was visually evaluated for the presence or absence of pinholes (defects).

[0120] A pinhole is a Figure 3 The defects generated in the film are shown by the circles in the figure.

[0121] 3) Melt flow index (MFI)

[0122] The measurement is carried out according to ASTM D1238 at 190°C and 2.16 kg. The unit is g / 10 minutes.

[0123] 4) Density

[0124] Measured according to ASTM D1505 and ASTM D792. Units are g / cm 3 .

[0125] 5) Inorganic Content

[0126] The inorganic content is determined by calculating the weight fraction of the residue that remains without being decomposed at 800° C. or higher when TGA measurement is performed according to the method 1) above.

[0127] Inorganic content = (weight of residue / weight of sample) × 100

[0128] 6) Weight average molecular weight (Mw) and number average molecular weight (Mn)

[0129] The weight average molecular weight (Mw) and number average molecular weight (Mn) were measured using GPC (Agilent GPC_1260InfitiyII New). GPC columns (Column) (PL1110-6400 and PL1110-1400) were used, and the column temperature was set to 160°C. 1,2,4-Trichlorobenzene was used as the solvent, polystyrene was used as the standard substance, and the analysis was performed at room temperature, 160°C, and a flow rate of 1 mL / min. In addition, the polydispersity index (PDI) value was calculated from the Mw and Mn. The specific conditions other than these are as follows.

[0130] Analytical apparatus: A GPC system (model name: Agilent's 1260 Infinity II High-Temperature GPC System) was used, which was connected to three columns (model name: Agilent's PLgel Olexis 7.5X300mm, 13μm) and one guard column (model name: Agilent's PLgel Olexis 7.5X50mm, 13μm), the temperature was set to 160°C, the GPC flow rate was set to 1 mL / min, and a differential refractometer was connected.

[0131] Sample preparation: In order to inject a sample solution with a concentration of 1.1-1.3 mg / ml into the GPC device, the sample solution was prepared in consideration of the amount of residue analyzed by TGA. At this time, 1 ml of 1,2,4-trichlorobenzene containing 200 ppm of butylated hydroxytoluene was used as the solvent. Stirring was performed at 160°C for 4 hours using a heating block, and then filtration was performed at 160°C using an external filtration system (model name: external filtration system of Polymerchar). 200 µL of the prepared solution was injected into the GPC and analyzed.

[0132] 7) Average Particle Size

[0133] The particle size and distribution of the material are measured using a particle size analyzer (Malvern Panalytical, product name: Mastersizer 3000 series). The particle size is calculated by irradiating a laser beam to the particles through the device and measuring the intensity of the scattered light. The average particle size refers to D50, that is, the size of the particles when accounting for 50% of the total particle size distribution. The unit is μm.

[0134] 8) Oil Absorption

[0135] An excess of linseed oil is mixed with the measurement sample to impregnate the sample with oil, and then centrifugation is performed to separate the sample and the oil. After that, the amount of linseed oil absorbed in the sample is measured by measuring the amount. The unit is ml / 100g, and it is the consumption (ml) of linseed oil per 100g of sample.

[0136] 9) Pore Volume

[0137] The pore volume is measured according to the Brunauer, Emmett and Teller (BET) method. The unit is ml / g.

[0138] 10) Loss-on-Drying Method (LOD)

[0139] The moisture content was measured by a halogen loss on drying meter, taking into account the difference (loss) in weight before and after drying. The drying conditions were 160° C. for 2 hours.

[0140] 11) pH

[0141] 5 g of porous powder was placed in a 100 mL beaker, 50 mL of water was added, the mixture was shaken and mixed, and then the pH was measured using a pH meter.

[0142] 12) Melting point

[0143] The melting point was measured by using a differential scanning calorimeter (DSC, Q20, TA Instruments) under a N2 atmosphere while heating from -50°C to 200°C at a rate of 10°C / min.

[0144] [Example 1]

[0145] [Preparation of recycled polyethylene composite composition]

[0146] The physical properties of the recycled polyethylene particles recovered from the separator of the secondary battery were measured and are shown in the following Table 1. In addition, the results of TGA analysis are shown in Figure 1 In. Figure 1 As shown, the peak of low molecular weight substances was found around 200-400°C.

[0147] In addition, physical properties of the porous silica powder are shown in Table 2 below.

[0148] 97 wt % of the recycled polyethylene and 3 wt % of porous silica powder were mixed in a twin-screw extruder while increasing the temperature from 170° C. to 210° C. at 150 rpm, thereby preparing a recycled polyethylene composite composition.

[0149] The TGA analysis results of the prepared recycled polyethylene composite composition are shown in Figure 2 In. Figure 2 As shown, confirmed Figure 1 The peak of the low molecular weight substance around 200-400°C shown in FIG.

[0150] [Manufacturing of regenerated membrane]

[0151] By mixing 70 wt% of the prepared recycled polyethylene composite composition and 30 wt% of virgin polyethylene resin (SK Geo Centric, YUZEX TM 8700) by dry mixing. The prepared mixture was added to a blow molding machine and extruded while heating from 180°C to 200°C under the condition that the number of revolutions per minute (rpm) of the screw was 60m / min. Air was injected into the extrudate extruded from the blow molding die to process it into a film form, and then cooled and wound at a roll speed of 6.8m / min to produce a film. The thickness of the produced film was 33μm.

[0152] The number of pinholes in the manufactured film was confirmed to be 1 / m 2Furthermore, it was confirmed that no breakage occurred during film production and that stable film formation was possible.

[0153] [Table 1]

[0154]

[0155] [Table 2]

[0156]

[0157] [Example 2]

[0158] The production was carried out in the same manner as in Example 1, except that, when preparing the recycled polyethylene composite composition, the content of the recycled polyethylene was adjusted to 95 wt % and the content of the porous silica powder was adjusted to 5 wt %.

[0159] The number of pinholes in the manufactured film was confirmed to be 1 / m 2 Furthermore, it was confirmed that no breakage occurred during film production and that stable film formation was possible.

[0160] [Example 3]

[0161] The production was carried out in the same manner as in Example 1, except that, when preparing the recycled polyethylene composite composition, the content of the recycled polyethylene was adjusted to 94 wt % and the content of the porous silica powder was adjusted to 6 wt %.

[0162] As a result, when the manufactured film was confirmed, it was confirmed that the surface quality was reduced due to the aggregation phenomenon of the silica powder. In addition, as the content of the porous silica powder increased, the viscosity of the composite composition increased, thereby increasing the load of the film extruder and causing the instability of the film bubbles.

[0163] [Example 4]

[0164] The production was carried out in the same manner as in Example 1, except that 3 wt % of porous silica powder having the physical properties shown in Table 3 below was mixed and used.

[0165] The number of pinholes in the manufactured film was confirmed to be 1 / m 2 Furthermore, it was confirmed that no breakage occurred during film production and that stable film formation was possible.

[0166] [Table 3]

[0167]

[0168] [Example 5]

[0169] The production was carried out in the same manner as in Example 1, except that 3 wt % of porous silica powder having the physical properties shown in Table 4 below was mixed and used.

[0170] The number of pinholes in the manufactured film was confirmed to be 1 / m 2 Furthermore, it was confirmed that no breakage occurred during film production and that stable film formation was possible.

[0171] [Table 4]

[0172]

[0173] [Example 6]

[0174] The production was carried out in the same manner as in Example 1, except that 3 wt % of porous silica powder having the physical properties shown in Table 5 below was mixed and used.

[0175] The number of pinholes in the manufactured film was confirmed to be 1 / m 2 Furthermore, it was confirmed that no breakage occurred during film production and that stable film formation was possible.

[0176] [Table 5]

[0177]

[0178] [Comparative Example 1]

[0179] In Example 1, the porous silica powder was not used, and recycled polyethylene recovered from the separator of the secondary battery was directly used as a raw material to produce a recycled membrane.

[0180] 70 wt% recycled polyethylene recovered from secondary battery separators and 30 wt% virgin polyethylene resin (SK Zhixin, YUZEX TM 8700), and the regenerated membrane was manufactured under the same conditions as in Example 1.

[0181] The results, such as Figure 3 As shown, the generation of pinholes was confirmed.

[0182] [Comparative Example 2]

[0183] The production was carried out in the same manner as in Example 1, except that, when preparing the recycled polyethylene composite composition, the porous silica powder was prepared as a masterbatch and added instead of being added in powder form.

[0184] That is, porous silica powder and polyethylene resin (SK Zhixin, YUZEX TM8700) to prepare a masterbatch, and then add the masterbatch in such a content that the content of porous silica powder in the film becomes 3 wt %, thereby preparing a recycled polyethylene composite composition. The recycled polyethylene composite composition was used to produce a film by the same method as in Example 1, and it was confirmed that many pinholes were generated in the recycled film.

[0185] [Comparative Example 3]

[0186] The production was carried out in the same manner as in Example 1, except that, in preparing the recycled polyethylene composite composition, non-porous titanium dioxide particles having an average particle size of 5 μm were used instead of the porous silicon dioxide powder.

[0187] As a result, it was confirmed that many pinholes were generated in the regenerated film.

[0188] The above contents are merely examples of applying the principles of the present invention, and other configurations may be included without departing from the scope of the present invention.

[0189] As described above, the present invention is described through specific contents and limited embodiments, but this is only provided to help a more comprehensive understanding of the present invention. The present invention is not limited to the above embodiments, and technicians in the field to which the present invention belongs can make various modifications and variations through such descriptions.

[0190] Therefore, the concept of the present invention should not be limited to the illustrated embodiments, and the claims of the present invention and all contents equivalent to the claims or having equivalent variations belong to the scope of the concept of the present invention.

Claims

1. A recycled polyethylene composite composition, wherein the recycled polyethylene composite composition is formed by mixing recycled polyethylene recovered from a separator of a secondary battery and a porous powder.

2. The recycled polyethylene composite composition according to claim 1, wherein The recycled polyethylene is a powder obtained by directly pulverizing a separator or a pellet obtained by melt-extrusion without going through a process of removing a coating layer from the separator.

3. The recycled polyethylene composite composition according to claim 1, wherein The content of the inorganic particles in the recycled polyethylene is 70 wt % or less.

4. The recycled polyethylene composite composition according to claim 1, wherein The melt flow index of the recycled polyethylene measured at 2.16 kg and 190° C. is less than 5 g / 10 minutes, and the density of the recycled polyethylene is 0.95 g / cm 3 In the above, the weight average molecular weight of the recycled polyethylene is greater than 50,000 g / mol.

5. The recycled polyethylene composite composition according to claim 1, wherein The total inorganic content of the recycled polyethylene composite composition, including the inorganic particles contained in the recycled polyethylene and the porous powder, is 50 wt % or less.

6. The recycled polyethylene composite composition according to claim 1, wherein The recycled polyethylene includes a low molecular weight substance, which decomposes and shows a peak at a lower temperature than a polyethylene standard substance in a result of measurement using a thermogravimetric analyzer (TGA).

7. The recycled polyethylene composite composition according to claim 6, wherein The low molecular weight substance is derived from a binder for coating of the separator.

8. The recycled polyethylene composite composition according to claim 7, wherein The content of the low molecular weight substance is 3 wt % or less in the total weight of the recycled polyethylene.

9. The recycled polyethylene composite composition according to claim 6, wherein: The weight average molecular weight of the low molecular weight substance is 5000 g / mol or less.

10. The recycled polyethylene composite composition according to claim 1, wherein The porous powder is mixed in a content of 5 wt % or less.

11. The recycled polyethylene composite composition according to claim 1, wherein The average particle size of the porous powder is 1-10 μm.

12. The recycled polyethylene composite composition according to claim 1, wherein: The oil absorption of the porous powder is 50-150 ml / 100 g.

13. The recycled polyethylene composite composition according to claim 1, wherein: The pore volume of the porous powder is 0.1-1.0 ml / g.

14. The recycled polyethylene composite composition according to claim 1, wherein: The porous powder is any one selected from porous silica, porous zeolite and porous alumina, or a mixture of two or more thereof.

15. A recycled film, comprising the recycled polyethylene composite composition according to any one of claims 1 to 14, wherein the number of pinholes is 1 / m 2 the following.

16. The regenerated membrane according to claim 15, wherein: The recycled polyethylene composite composition is prepared by premixing recycled polyethylene recovered from a separator of a secondary battery and porous powder.

17. The regenerated membrane according to claim 15, wherein: The recycled film further comprises a virgin polyolefin-based resin.

18. The regenerated membrane according to claim 17, wherein: The recycled film comprises 60-90 wt % of the recycled polyethylene composite composition and 10-40 wt % of a virgin polyolefin-based resin.

19. The regenerated membrane according to claim 15, wherein: The thickness of the regenerated film is 10-200 μm.

20. A method for producing a regenerated membrane, comprising the following steps: Premixing recycled polyethylene recovered from a separator of a secondary battery and a porous powder to prepare a recycled polyethylene composite composition; The recycled polyethylene composite composition and virgin polyolefin-based resin are melt-extruded to produce a film.

21. The method for producing a regenerated membrane according to claim 20, wherein: The step of manufacturing the film comprises the following steps: The recycled polyethylene composite composition and the virgin polyolefin-based resin are melt-extruded to prepare pellets or dry-mixed to prepare a mixture; The pellets or the mixture are melt-extruded to produce a film.

22. The method for producing a regenerated membrane according to claim 20, wherein: The premix is ​​selected from the following (i) to (iii): (i) A method of dry mixing powdered or granular recycled polyethylene and powdered porous powder; (ii) a method in which powdered or granular recycled polyethylene and powdered porous powder are quantitatively added into a batch mixer at one time and mixed; as well as (iii) A method comprising the steps of metering the porous powder in powder form through a side feeder of an extruder and mixing it with recycled polyethylene in powder form or granular form.

23. The method for producing a regenerated membrane according to claim 20, wherein: The recycled polyethylene is a powder obtained by directly pulverizing a separator or a pellet obtained by melt-extrusion without going through a process of removing a coating layer from the separator.

Images