Recycled polyethylene compound composition and recycled film using the same

Abstract

To provide a recycled polyethylene compound composition and a recycled film using the same.SOLUTION: The present disclosure relates to a recycled polyethylene compound composition using polyethylene recovered from a secondary battery separator as a raw material, and to a recycled film using the same. According to the present disclosure, a separator on which a coating layer containing an organic binder and / or inorganic particles formed may be reused as it is as a recycled raw material without any pre-processing process, and a composition for manufacturing a film may be provided.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a recycled polyethylene compound composition and a recycled film using the same.

Background Art

[0002] With the popularization of the use of secondary batteries, the number of secondary batteries that are discarded after their lifespan is exhausted is also increasing. Therefore, various methods for recycling discarded secondary batteries have been studied. For example, by collecting discarded secondary batteries and performing pretreatment operations including discharging, crushing, and sorting processes, the outer can, separator, and negative / positive electrodes can be classified, and then metals such as cobalt, nickel, lithium, and manganese can be recovered.

[0003] However, most of the waste separators recovered from the waste secondary batteries, waste separators from defective products, or separator scraps generated in the manufacturing process cannot be recycled and are treated by inappropriate methods such as incineration, so it has been pointed out that it causes waste of resources and environmental pollution.

[0004] Therefore, in order to solve the above problems, various efforts have been made to recycle waste separators. However, since the physical properties and processability of the waste separators themselves are not sufficient, it is necessary to adjust them to be suitable for the intended use and molding method for recycling.

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to one aspect of the present disclosure, a recycled polyethylene compound composition for manufacturing a recycled film containing polyethylene recovered from a separator of a secondary battery can be provided.

[0006] According to another aspect of the present disclosure, a recycled film can be provided that reuses polyethylene recovered from a separator of a secondary battery as a raw material. Further, a recycled polyethylene compound composition that can be used as a recycled polyethylene raw material as it is without another pretreatment process such as removing a coating layer from the polyethylene recovered from the separator of the secondary battery can be provided.

[0007] According to another aspect of the present disclosure, a recycled film without defects such as pinholes can be provided even though the recycled film is manufactured using polyethylene recovered from a separator of a secondary battery as a raw material.

Means for Solving the Problems

[0008] The recycled polyethylene compound composition according to the present disclosure includes recycled polyethylene recovered from a separator of a secondary battery and porous powder. As one embodiment, the recycled polyethylene and the porous powder in the recycled polyethylene compound composition may be dry blended or melted.

[0009] As one embodiment, the recycled polyethylene may be powder obtained by directly pulverizing the separator or pellets obtained by melt extrusion without a process of removing the coating layer from the separator.

[0010] As one embodiment, the content of inorganic particles in the recycled polyethylene may be 70% by weight or less, but is not limited thereto.

[0011] As one embodiment, the total content of inorganic substances including the inorganic particles contained in the recycled polyethylene and the porous powder in the recycled polyethylene compound composition may be 50% by weight or less, but is not limited thereto.

[0012] As one embodiment, the recycled polyethylene has a melt flow index measured at 2.16 kg and 190 °C of 5 g / 10 min or less, a density of 0.95 g / cm 3 or more, and the weight average molecular weight may be 50,000 g / mol or more, but is not limited thereto.

[0013] As one embodiment, the recycled polyethylene may include low molecular weight substances that are decomposed at a lower temperature than the polyethylene reference substance and show peaks as a result of measurement using a thermogravimetric analyzer (TGA). The low molecular weight substances refer to substances measured by the measurement method described later. The measurement method of the thermogravimetric analyzer (TGA) is measured by the measurement method described later. As one embodiment, the lower temperature relative to the polyethylene reference substance may show a peak at 200 to 400 °C.

[0014] As one embodiment, the low molecular weight substance may be derived from the binder for the coating layer of the separator.

[0015] As one embodiment, the content of the low molecular weight substance may be 3% by weight or less based on the total weight of the recycled polyethylene. The content of the low molecular weight substance is calculated by the method described later.

[0016] As one embodiment, the low molecular weight substance may have a weight average molecular weight of 5000 g / mol or less. The weight average molecular weight is measured by the measurement method described later.

[0017] As one embodiment, the porous powder may be mixed at a content of 5% by weight or less, but is not limited thereto.

[0018] As one embodiment, the porous powder may have an average particle size of 1 to 10 μm, but is not limited thereto.

[0019] As an embodiment, the porous powder may have an oil absorption of 50 to 150 cc / 100 g, but is not limited thereto.

[0020] As an embodiment, the porous powder may have a pore volume of 0.1 to 1.0 ml / g, but is not limited thereto.

[0021] As an embodiment, the porous powder may be any one or a mixture of two or more selected from the group consisting of porous silica, porous zeolite, and porous alumina.

[0022] Another aspect of the present disclosure includes the recycled polyethylene compound composition according to the above embodiment, and provides a recycled film having the number of pinholes of 1 piece / m 2 as follows.

[0023] As an embodiment, the recycled polyethylene compound composition may be obtained by pre-mixing recycled polyethylene recovered from a separator of a secondary battery and powdery porous powder. As an embodiment, the pre-mixing may be dry blended or melted.

[0024] As an embodiment, the recycled film may further include a virgin polyolefin resin.

[0025] As an embodiment, the recycled film may include 60 to 90% by weight of the recycled polyethylene compound composition and 10 to 40% by weight of the virgin polyolefin resin, but is not limited thereto.

[0026] As an embodiment, the recycled film may have a thickness of 10 to 200 μm, but is not limited thereto.

[0027] Other embodiments of the present disclosure include the step of pre-mixing recycled polyethylene recovered from a separator of a secondary battery and a porous powder to produce a recycled polyethylene compound composition, and a step of melt-extruding the recycled polyethylene compound composition and a virgin polyolefin resin to produce a film, and provide a method for producing a recycled film.

[0028] In one embodiment, in the step of producing the film, the step of melt-extruding the recycled polyethylene compound composition and the virgin polyolefin resin to produce pellets or dry-blending them to produce a mixture, and the step of melt-extruding the pellets or the mixture to produce a film may be included.

[0029] In one embodiment, the pre-mixing may be selected from the following (i) to (iii). (i) A method of dry-blending recycled polyethylene in powder or pellet form and porous powder in powder form, (ii) A method of simultaneously metering and mixing recycled polyethylene in powder or pellet form and porous powder in powder form into a batch mixer, and (iii) A method including the step of metering and introducing porous powder in powder form by a side feeder of an extruder and mixing it with recycled polyethylene in powder or pellet form.

[0030] In one embodiment, the recycled polyethylene may be powder obtained by directly pulverizing the separator without removing the coating layer from the separator or pellets obtained by melt-extruding it.

Advantages of the Invention

[0031] The recycled polyethylene compound composition according to an embodiment of the present disclosure contains polyethylene recovered from the separator of a secondary battery and can be reused as a raw material for film production despite containing coating compositions, inorganic particles, etc. used during the production of the separator.

[0032] In addition, recycled films using this as a raw material can prevent defects such as pinholes from occurring.

[0033] The recycled film according to an embodiment of the present disclosure is applicable in various film fields such as separators for secondary batteries and recycled garbage bags.

Brief Description of the Drawings

[0034]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0035] Hereinafter, the present disclosure will be described in detail. However, this is merely exemplary and the present disclosure is not limited to the specific embodiments illustrated.

[0036] Also, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. The terms used in the description of this disclosure are for the purpose of effectively describing specific examples only and are not intended to limit the present disclosure.

[0037] Also, the singular forms used in the specification and the appended claims are intended to include the plural forms as well, unless otherwise specifically stated in the context.

[0038] Also, when a part states that a certain component "comprises", this means that, unless otherwise stated to the contrary, it does not exclude other components but may further include other components.

[0039] Also, unless otherwise specifically defined, when a layer or member is located "on" another layer or member, this includes not only the case where a layer or member is in contact with another layer or member, but also the case where there is still another layer or still another member between the two layers or the two members.

[0040] Also, terms such as "about" and "substantially" are used in the sense of that numerical value or close to that numerical value when manufacturing and material tolerances inherent in the recited meaning are presented, and are used to prevent unscrupulous infringers from improperly using the disclosed content where exact or absolute numerical values are recited for the purpose of facilitating the understanding of the present disclosure.

[0041] As one embodiment of the present disclosure, "recycled polyethylene" means polyethylene recovered from the separator of a secondary battery, which is powder obtained by pulverizing any one or two or more waste separators selected from separators separated and recovered by disassembling waste secondary batteries, separators recovered from defective products of secondary batteries, waste scraps generated during the manufacture of separators of secondary batteries, and ends of separators recovered after trimming, or is obtained by melt extrusion and processed into pellets. Although not limited, when processed into pellets, the melt extrusion temperature may be 200 to 250 °C.

[0042] As one embodiment of the present disclosure, the "low molecular weight substance" means a substance of a peak that appears at a temperature lower than the main peak when analyzing the polyethylene raw material recovered from the separator of a secondary battery using a thermogravimetric analyzer (TGA), compared with the graph of the virgin polyethylene with a weight average molecular weight of 50,000 to 2,000,000 g / mol, which is the reference substance. For example, as illustrated in FIG. 1, it means a substance of a peak that appears at 200 to 400 °C, which is a temperature lower than the main peak of 400 to 600 °C. Further, the reference substance means a virgin polyethylene resin that has not been manufactured as a separator, and may be a virgin polyethylene resin having the same or similar weight average molecular weight as the recycled polyethylene recovered from the separator of the secondary battery. The content of the low molecular weight substance can be calculated by the method described later.

[0043] In one embodiment of the present disclosure, the "pinhole" means a defect found in a film manufactured like the portion indicated by 〇 in FIG. 3. The form 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 where a hole is formed. For example, it may be a defect with a diameter of 1 mm or more, a defect with a diameter of 1 to 10 mm, or larger or smaller than this. The diameter means the minimum length among the forms of the pinhole. That is, as illustrated in FIG. 3, in the case of an elliptical pinhole with a narrow width and a long length, it means the diameter of the narrow width.

[0044] Hereinafter, the present disclosure will be described more specifically.

[0045] One embodiment of the present disclosure provides a recycled polyethylene compound composition in which recycled polyethylene recovered from a separator of a secondary battery and porous powder are mixed.

[0046] The inventors have conducted extensive research to manufacture a recycled film using recycled polyethylene recovered from the separator of a secondary battery as a raw material. When manufacturing a recycled film using the recovered recycled polyethylene as a raw material, as shown in Figure 3, it was confirmed that defects such as pinholes occurred.

[0047] To solve this problem, as a result of measuring the recovered recycled polyethylene using a thermogravimetric analyzer (TGA), when compared with the graph of virgin polyethylene having the same molecular weight as the polyethylene of the separator of the recovered secondary battery, as shown in Figure 1, it was confirmed that a peak was further discovered at 200 to 400 °C. The substance discovered from such a peak was regarded as a low molecular weight substance, and a prediction was made as to where such a low molecular weight substance originated.

[0048] Generally, the separator of a secondary battery is a microporous membrane made of a polyethylene resin, and a ceramic layer is formed on one or both surfaces thereof. In the ceramic layer, inorganic particles are bonded and fixed by a binder. It is expected that the low molecular weight substance originates from the binder used in the ceramic layer.

[0049] In order to manufacture a film, processing is performed at a temperature equal to or higher than the melting point of polyethylene, which is the raw material. Since such a low molecular weight substance vaporizes at such a temperature, it is expected that defects such as pinholes will occur on the surface of the film. When pinholes occur, the appearance and physical properties of the film deteriorate, and it is determined as defective.

[0050] Therefore, as a result of extensive research to solve the problem caused by the low molecular weight substance in the recycled polyethylene recovered from the separator of a secondary battery, it was found that problems such as pinholes can be solved by mixing porous powder to produce a compound composition, and the present disclosure was completed.

[0051] Hereinafter, each configuration of the present disclosure will be described more specifically.

[0052] [Recycled polyethylene compound composition] The recycled polyethylene compound composition according to one embodiment of the present disclosure may be prepared by mixing recycled polyethylene recovered from a separator of a secondary battery and porous powder. Here, the mixing may be carried out such that the porous powder is mixed with the recycled polyethylene in a powder state. By mixing in a powder state, defects of the film targeted in the present disclosure can be eliminated.

[0053] The mixing method is not limited, but may be compounded by dry blending or an extruder, etc. For example, a method of dry blending (Dry Blend) recycled polyethylene in a powder or pellet state and porous powder in a powder state, a method of simultaneously metering and feeding recycled polyethylene in a powder or pellet state and porous powder in a powder state in a batch mixer, or after introducing recycled polyethylene in a powder or pellet state through the feed of an extruder, porous powder in a powder state may be metered and introduced through a side feeder and mixed. The conditions during the mixing are not limited, but when compounding using an extruder, it may be 150°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, 190°C or higher, 200°C or higher, 300°C or lower, 290°C or lower, 280°C or lower, 270°C or lower, 260°C or lower, 250°C or lower, or any value between the above numerical values. For example, it may be carried out in the range of 150 to 300°C, 170 to 250°C, 170 to 230°C, 170 to 210°C. When mixing within the above range, generation of carbides may be reduced, and removal of low molecular weight substances in the separator may be efficiently carried out, but it is not limited thereto.

[0054] [Recycled polyethylene recovered from a separator of a secondary battery] The separator of a secondary battery usually includes a microporous membrane made of a polyethylene resin and a ceramic coating layer in which inorganic particles are bonded and fixed by a binder on one or both surfaces thereof. Alternatively, if necessary, an adhesive layer containing organic binder particles may be formed to improve the adhesiveness to the electrode.

[0055] The recycled polyethylene according to one embodiment of the present disclosure thus separates only the microporous membrane made of polyethylene resin from the separator having various laminated structures and uses it not only as a raw material, but also the separator including the ceramic coating layer or the adhesive layer may be used as a raw material as it is.

[0056] As one embodiment of the present disclosure, the recycled polyethylene may be produced and used as a raw material in a powder state obtained by pulverizing the separator as it is or in a pellet state by melt extrusion without a process of removing the coating layer from the separator. Therefore, the recycled polyethylene according to one embodiment of the present disclosure may include various substances such as inorganic particles and binders in addition to the polyethylene resin.

[0057] The recycled polyethylene containing the various substances may satisfy the following physical properties.

[0058] As one embodiment, the molecular weight of the recycled polyethylene is usually not limited as long as it is the molecular weight of the polyethylene used for the microporous membrane which is a porous base material in the separator. For example, the weight average molecular weight (Mw) may 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, or any value between the above numerical values. For example, it may be 50,000 to 3,000,000 g / mol, 50,000 to 2,000,000 g / mol, 80,000 to 1,500,000 g / mol, 100,000 to 1,000,000 g / mol, 100,000 to 500,000 g / mol, 100,000 to 300,000 g / mol, 150,000 to 250,000 g / mol, and is not limited thereto. The weight average molecular weight may be measured by the measurement method described below.

[0059] For example, the number average molecular weight (Mn) may be 20,000 g / mol or more, 30,000 g / mol or more, 40,000 g / mol or more, 50,000 g / mol or more, 1,000,000 g / mol or less, 800,000 g / mol or less, 500,000 g / mol or less, 300,000 g / mol or less, and may also be any value between the above numerical values. For example, it may be 20,000 to 1,000,000 g / mol, 30,000 to 800,000 g / mol, 30,000 to 500,000 g / mol, 30,000 to 300,000 g / mol, 30,000 to 100,000 g / mol, and is not limited thereto. The number average molecular weight may be measured by the measurement method described below.

[0060] Also, in accordance with ASTM D1238, the melt flow index 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, 0.07 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 may also be any value between the above numerical values. For example, it may be 0.01 to 5 g / 10 min, 0.01 to 4 g / 10 min, 0.01 to 3 g / 10 min, 0.01 to 2 g / 10 min, 0.01 to 1 g / 10 min, 0.01 to 0.9 g / 10 min, 0.01 to 0.5 g / 10 min, 0.01 to 3 g / 10 min, 0.01 to 2 g / 10 min, 0.01 to 1 g / 10 min.

[0061] Also, the content of the inorganic particles may 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 may be any value between the above ranges. For example, it may be 1 to 70% by weight, 2 to 50% by weight, 3 to 30% by weight, 5 to 30% by weight, 10 to 30% by weight, 15 to 30% by weight, 20 to 25% by weight, but is not limited thereto. The content of the inorganic particles is the content determined during the manufacture of the separator, and may provide a melt flow index that can be melt-extruded and formed within the above range, but is not limited thereto. The inorganic particles may be contained in the ceramic coating layer or the microporous membrane itself.

[0062] Also, the density measured according to ASTM D 792 is 0.95 g / cm 3 or more, 1.0 g / cm 3 or more, 1.1 g / cm 3 or more, 1.2 g / cm 3 or more, 1.3 g / cm 3 or more, 1.4 g / cm 3 or more, 1.5 g / cm 3 or less, and may be any value between the above numerical values. For example, it may be 0.95 to 1.5 g / cm 3 , 0.95 to 1.3 g / cm 3 , 0.95 to 1.2 g / cm 3 , 1.0 to 1.2 g / cm 3 and may be.

[0063] Also, the melting point (Tm) may be 100 °C or higher, 110 °C or higher, 120 °C or higher, 130 °C or higher, 140 °C or higher, 250 °C or lower, 240 °C or lower, 230 °C or lower, 220 °C or lower, 210 °C or lower, 200 °C or lower, 180 °C or lower, 170 °C or lower, 160 °C or lower, 150 °C or lower, or any value between the above values. For example, it can be 100 to 250 °C, 110 to 230 °C, 120 to 200 °C, 120 to 180 °C, 120 to 160 °C, 120 to 150 °C, but is not limited thereto. The melting point is measured by the method described below.

[0064] Although not limited, when the recycled polyethylene satisfies the above range, it can be melt-extruded and formed, so it can be manufactured as a recycled film, which is more preferable.

[0065] As one embodiment, the content of the low molecular weight substance in the recycled polyethylene may be 3% by weight or less, 2% by weight or less, 1% by weight or less based on the total weight of the recycled polyethylene, or any numerical value between the above values, but is not limited thereto. The content of the low molecular weight substance can be obtained by calculating the area value for the low molecular weight substance with a molecular weight of 5000 g / mol or less using the calibration curve of GPC (Gel Permeation Chromatography). Alternatively, the weight loss ratio around 200 to 400 °C can be measured using TGA (Thermogravimetric Analysis) data, and compared with the weight of the whole sample to obtain the ratio of the low molecular weight substance.

[0066] As one embodiment, the weight average molecular weight of the low molecular weight substance contained in the recycled polyethylene may be in a range lower than that of the polyethylene microporous membrane which is the porous base material of the separator. For example, the weight average molecular weight may be 5000 g / mol or less, 4500 g / mol or less, 4000 g / mol or less, 3500 g / mol or less, 3000 g / mol or less, 100 g / mol or more, 500 g / mol or more, 600 g / mol or more, 700 g / mol or more, 800 g / mol or more, 900 g / mol or more, 1000 g / mol or more, and may be any value between the above numerical values. For example, the weight average molecular weight may be 500 to 5000 g / mol, 1000 to 5000 g / mol, 1000 to 4500 g / mol, 1000 to 4000 g / mol, 1000 to 3000 g / mol, but is not limited thereto. The weight average molecular weight of the low molecular weight substance is measured by a specific method described later.

[0067] [Porous powder] As one embodiment of the present disclosure, the porous powder may be porous particles in a powder state. For example, it may be any one or a mixture of two or more selected from the group consisting of porous silica, porous zeolite, porous alumina, etc., but is not limited thereto. In the present disclosure, the porous particles in the powder state mean porous particles in a powder state that are separately added and distinguished from the inorganic particles contained in the separator of the secondary battery.

[0068] As one embodiment, the content of the porous powder may be 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or more in the recycled polyethylene compound composition, and may be any value between the above numerical values. For example, it can be used at a content of 2 to 5% by weight or 3 to 5% by weight. In this range, the film formability is excellent, and it is sufficient to prevent the occurrence of defects in the film. When the content of the porous powder is added excessively, the viscosity increases, the load on the extruder may increase during film extrusion, and the productivity may decrease during film production. In addition, the aggregation phenomenon of the porous powder may occur, and the quality of the film surface may decrease.

[0069] Further, in the recycled polyethylene compound composition, the content of the total inorganic substances including the inorganic particles contained in the recycled polyethylene and the porous powder may 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, or may be any value between the above numerical values. For example, it may be 10 to 50% by weight, 15 to 45% by weight, 20 to 40% by weight, 22 to 30% by weight. Although not limited thereto, excellent film formability can be achieved within the above range.

[0070] As one embodiment, the porous powder may have an average particle size of 1 to 10 μm, an oil absorption amount of 50 to 150 cc / 100 g, and a pore volume of 0.1 to 1.0 ml / g. It is preferable because it has an excellent effect of reducing the generation of pinholes caused by low molecular weight substances of recycled polyethylene recovered from a separator of a secondary battery according to an embodiment of the present disclosure within the above range, but is not limited thereto.

[0071] As one embodiment, the porous powder may have an average particle size of 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, or may be any value between the above numerical values. For example, the average particle size may be 1 to 10 μm, 1 to 9 μm, 1 to 8 μm, 1 to 7 μm, 2 to 6 μm, and is not limited thereto. The average particle size may be measured by the measurement method described later.

[0072] As an embodiment, the porous powder may have an oil absorption amount of 50 cc / 100 g or more, 60 cc / 100 g or more, 70 cc / 100 g or more, 80 cc / 100 g or more, 90 cc / 100 g or more, 95 cc / 100 g or more, 150 cc / 100 g or less, 140 cc / 100 g or less, 135 cc / 100 g or less, 130 cc / 100 g or less, 120 cc / 100 g or less, 110 cc / 100 g or less, 100 cc / 100 g or less, or any value between the above values. For example, it may be 50 - 150 cc / 100 g, 60 - 150 cc / 100 g, 70 - 150 cc / 100 g, 80 - 140 cc / 100 g, 90 - 135 cc / 100 g, but is not limited thereto. The oil absorption amount may be measured by the measurement method described below.

[0073] As an embodiment, the porous powder may have a pore volume of 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, or any value between the above values. For example, the pore volume 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, but is not limited thereto. The pore volume can be measured by the measurement method described below.

[0074] As an embodiment, the porous powder may have a pH of 4 or more, 5 or more, 8 or less, 7.5 or less, 7 or less, 6 or less, or any value between the above values. For example, it may be 4 - 8, but is not limited thereto. The pH may be measured by the measurement method described below.

[0075] As one embodiment, the moisture content of the porous powder by the Loss-on-Drying Method (LOD) may 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. The lower limit is not limited, but may be 0.1 wt% or more. Also, it may be any value between the above numerical values. For example, it may be 0.1 - 5 wt%, 0.1 - 4 wt%, 0.1 - 3.5 wt%, but is not limited thereto. The moisture content can be measured by the measurement method described later.

[0076] As one embodiment, the porous powder is preferably mixed with the recycled polyethylene in a powder state, and can achieve the effect of removing defects such as target pinholes. Although it is not excluded to mix the porous powder with a polyethylene resin to produce a masterbatch and add it, in the present disclosure, when the porous powder is mixed with the recycled polyethylene in a powder state for pre-mixing, the low molecular weight substances of the recycled polyethylene can be removed even better.

[0077] [Recycled Film and Its Manufacturing Method] One embodiment of the present disclosure provides a recycled film manufactured using the recycled polyethylene compound composition.

[0078] As one embodiment, the recycled film has 1 pinhole / m 2 or less, or substantially no pinholes are formed, that is, a recycled film with 0 pinholes / m 2 is provided. For example, the number of pinholes may be 0 - 1 pinhole / m 2 , 0.01 - 1 pinhole / m 2 , 0.05 - 1 pinhole / m 2 , 0.1 - 1 pinhole / m 2 , 0.2 - 1 pinhole / m 2 , 0.3 - 1 pinhole / m 2 , but is not limited thereto. The pinholes may be measured by the measurement method described later.

[0079] As one embodiment, the composition for film production may include the recycled polyethylene compound composition alone. As one embodiment, the composition for film production may include the recycled polyethylene compound composition and a virgin polyolefin resin.

[0080] The virgin polyolefin resin means a new product that has never been used and may be selected from the group consisting of polyethylene, polypropylene, and the like.

[0081] According to the physical properties of the recycled film to be finally produced, the physical properties of the virgin polyolefin resin may be adjusted and used, and its physical properties are not limited. For example, the virgin polyolefin resin may be a polyethylene resin.

[0082] As one embodiment, the composition for film production may include 60 to 90% by weight of the recycled polyethylene compound composition and 10 to 40% by weight of the virgin polyolefin resin. Also, it may include 70 to 80% by weight of the recycled polyethylene compound composition and 20 to 30% by weight of the virgin polyolefin resin. Within the range of the content, a recycled film with excellent processability and excellent mechanical physical properties can be produced. However, the mixing ratio can be changed according to the physical properties of the virgin polyolefin resin to be mixed, and it is not limited thereto.

[0083] As one embodiment, the composition for film production may further include additives such as inorganic particles, anti-blocking agents, ultraviolet blockers, pigments, etc., which are usually used in the production of films, if necessary, and it is not limited thereto. The content of the additive may be 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, 0.1% by weight or more, 0.2% by weight or more, 0.5% by weight or more, or any value between the above numerical values. For example, it may be 0.1 to 5% by weight, 0.2 to 4% by weight, and it is not limited thereto.

[0084] As an embodiment, the thickness of the recycled film may 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, or any value between the above numerical values. For example, it may be 10 - 200 μm, 20 - 100 μm, 30 - 80 μm, etc., but not limited thereto. The thickness of the film may be measured using a thickness measuring instrument (TELCLOCK COPORATION, PG - 02).

[0085] Next, a method for manufacturing a recycled film according to an embodiment of the present disclosure will be described.

[0086] The method for manufacturing a recycled film according to an embodiment of the present disclosure includes a step of pre - mixing recycled polyethylene recovered from a separator of a secondary battery and powdery porous powder to produce a recycled polyethylene compound composition, and a step of melt - extruding the recycled polyethylene compound composition and virgin polyolefin - based resin to produce a film.

[0087] As an embodiment, the recycled polyethylene compound composition may be produced by pre - mixing recycled polyethylene recovered from a separator of a secondary battery and powdery porous powder. The pre - mixing may use not only an extruder but also a reactor usually used for producing a compound composition. For example, at the time of the pre - mixing, it may be produced by a method selected from the following (i) to (iii), but not limited thereto.

[0088] (i) A method of dry - blending recycled polyethylene in powder or pellet form and porous powder in powder form (ii) A method of simultaneously metering and mixing recycled polyethylene in powder or pellet form and porous powder in powder form into a batch mixer, and (iii) A method comprising the step of metering porous powder in powder form into a side feeder of an extruder and mixing it with recycled polyethylene in powder or pellet form.

[0089] As one embodiment, the temperature conditions during the mixing are not limited, but when compounding using an extruder, it may be 150°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, 190°C or higher, 200°C or higher, 300°C or lower, 290°C or lower, 280°C or lower, 270°C or lower, 260°C or lower, 250°C or lower, and may be any value between the above numerical values. For example, it may be carried out in the range of 150 - 300°C, 170 - 250°C, 170 - 230°C, 170 - 210°C. When mixing within the above range, the generation of carbides can be reduced, and the removal of low-molecular-weight substances in the separator can be efficiently carried out, but it is not limited thereto.

[0090] As one embodiment, the recycled polyethylene compound composition and virgin polyolefin resin are melt-extruded to produce a film. Here, the step of melt-extruding the recycled polyethylene compound composition and virgin polyolefin resin to produce pellets or dry-blending them to produce a mixture, and then melt-extruding the pellets or mixture to produce a film may also be carried out. When producing the pellets, the melting temperature is not limited, but it may be 150°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, 190°C or higher, 200°C or higher, 300°C or lower, 290°C or lower, 280°C or lower, 270°C or lower, 260°C or lower, 250°C or lower, and may be any value between the above numerical values. For example, it may be carried out in the range of 150 - 300°C, 170 - 250°C, 170 - 230°C, 170 - 210°C.

[0091] Also, when producing the film by melt extrusion, the melt temperature is not limited, but may be 150°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, 190°C or higher, 200°C or higher, 300°C or lower, 290°C or lower, 280°C or lower, 270°C or lower, 260°C or lower, 250°C or lower, or may be any value between the above numerical values. For example, it may be carried out in the range of 150 - 300°C, 170 - 250°C, 180 - 230°C, 180 - 210°C, 180 - 200°C.

[0092] As one embodiment, the step of manufacturing the film may be carried out by using a blown extruder or by manufacturing it in a sheet form using a T-die and then performing uniaxial or biaxial stretching.

[0093] Hereinafter, with reference to specific experimental examples, the embodiments of the present disclosure will be further described. The examples and comparative examples included in the experimental examples are illustrative of the present disclosure and do not limit the scope of the appended patent claims. It is obvious to those skilled in the art that various changes and modifications to the examples are possible within the scope of the present disclosure and the scope of the technical idea, and it is natural that such deformations and modifications belong to the scope of the appended patent claims.

[0094] Hereinafter, the physical properties were evaluated as follows.

[0095] 1) Presence and content of low molecular weight substances Measured using TGA (manufactured by TA Instruments, / TGA Q500 product).

[0096] A test piece of about 10 mg was prepared in a TGA Pan container.

[0097] The prepared sample was placed in a TGA Auto Sampler, and analysis was performed by selecting the desired temperature range, heating rate, and reactive gas. The temperature was raised from room temperature to 900°C at 10°C / min, and the gas atmosphere was changed from N 2 gas atmosphere to air atmosphere at 700°C.

[0098] Experimental temperature range: room temperature to 900 °C / 700 °C Air change (N 2 ->Air) Atmosphere: N 2 Heating rate: 10 °C / min

[0099] In addition, the content of low molecular weight substances with a weight average molecular weight of 5000 g / mol or less can be confirmed by checking the weight loss ratio near 200 to 400 °C in the TGA data and calculating the ratio of low molecular weight substances to the total weight.

[0100] 2) Presence or absence of pinholes The presence or absence of pinholes (defects) in the manufactured film was visually evaluated.

[0101] Pinholes mean defects that occur in the film, as indicated by ○ in Figure 3.

[0102] 3) Melt Flow Index (MFI) Measured according to ASTM D 1238 at 190 °C and 2.16 kg. The unit is g / 10 min.

[0103] 4) Density Measured according to ASTM D1505 and ASTM D 792. The unit is g / cm 3 is.

[0104] 5) Inorganic content The inorganic content was calculated and confirmed by calculating the weight fraction of the residue that remained without decomposing at 800 °C or higher during the TGA measurement by the method of item 1) above.

[0105] Inorganic content = (weight of residue / weight of sample) × 100

[0106] 6) Weight average molecular weight (Mw) and number average molecular weight (Mn) The weight-average molecular weight (Mw) and number-average molecular weight (Mn) were measured using a GPC (manufactured by Agilent, GPC_1260InfitiyII New). GPC columns (PL1110-6400 and PL1110-1400) were used, and the temperature of the columns was set at 160°C. The solvent was 1,2,4-trichlorobenzene, and the standard was polystyrene. Analysis was performed at room temperature, 160°C, and a flow rate of 1 mL / min. In addition, the value of the polydispersity index (PDI) was calculated from the Mw and Mn. Other specific conditions are as follows.

[0107] Analytical instrument: A GPC system (model name: Agilent 1260 Infinity II High-Temperature GPC System) with three columns (model name: Agilent PLgel Olexis 7.5×300 mm, 13 μm) and one guard column (model name: Agilent PLgel Olexis 7.5×50 mm, 13 μm) connected, temperature set at 160°C, GPC flow rate 1 mL / min, and a refractive index detector connected was used.

[0108] Sample preparation: To inject a sample solution with a concentration of 1.1 - 1.3 mg / ml into the GPC instrument, a sample solution was prepared considering the amount of residue analyzed by TGA. Here, the solvent used was butylated hydroxytoluene and 1 ml of 200 ppm 1,2,4-trichlorobenzene. After stirring at 160°C for 4 hours using a heating block, filtration was performed at 160°C using an External filtration system (model name: Polymerchar External Filtration System). 200 μL of the prepared solution was injected into the GPC and analyzed.

[0109] 7) Average Particle Size The particle size and its distribution of the substance were measured by using a particle size analyzer (manufactured by Malvern Panalytical, product name: Mastersizer 3000 series). The instrument irradiated the particles with a laser beam, measured the intensity of the scattered light, and calculated the particle size. The average particle size means D50, that is, the particle size at 50% in the overall particle size distribution. The unit is μm.

[0110] 8) Oil Absorption An excessive amount of linseed oil was mixed with the measurement sample to impregnate the sample with oil, and then centrifuged to separate the sample and the oil. Next, the amount was measured to determine the amount of linseed oil absorbed in the sample. The unit is cc / 100g, which is the consumption (cc) of linseed oil per 100 g of the sample.

[0111] 9) Pore Volume The pore volume was measured by the BET (Brunauer, Emmett and Teller) measurement method. The unit is ml / g.

[0112] 10) Loss-on-Drying Method (LOD) Using a halogen loss-on-drying measuring instrument, the moisture content was measured considering the difference in weight (loss) before and after drying. The drying conditions were carried out at 160 °C for 2 hours.

[0113] 11) pH 5 g of porous powder was placed in a 100 mL beaker, 50 ml of water was added, shaken and mixed, and then measured using a pH meter.

[0114] 12) Melting Point Using a differential scanning calorimeter (DSC, Q20, manufactured by TA instrument), the melting point was measured while heating from -50 °C to 200 °C at a rate of 10 °C / min in an N 2 environment.

[0115] [Example 1] [Production of Recycled Polyethylene Compound Composition] The physical properties of recycled polyethylene pellets recovered from the separator of a secondary battery were measured and shown in Table 1 below. Also, the results of TGA analysis were illustrated in Figure 1. As shown in Figure 1, a peak of low molecular weight substances was found around 200 - 400°C.

[0116] Also, the physical properties of the porous silica powder were shown in Table 2 below.

[0117] 97 wt% of the recycled polyethylene and 3 wt% of the porous silica powder were mixed from a twin - screw extruder at 150 rpm while raising the temperature from 170°C to 210°C to produce a recycled polyethylene compound composition.

[0118] The TGA analysis results of the produced recycled polyethylene compound composition were illustrated in Figure 2. As shown in Figure 2, it was confirmed that the peak of the low molecular weight substances around 200 - 400°C shown in Figure 1 disappeared.

[0119] [Production of Recycled Film] 70 wt% of the produced recycled polyethylene compound composition and 30 wt% of virgin polyethylene resin (SK Geo Centric, YUZEX TM 8700) were prepared by pre - dry - blending (Dry Blend). The prepared mixture was put into a blown - film extruder and extruded while raising the temperature from 180°C to 200°C under the condition that the screw rpm was 60 m / min. Air was injected into the extrudate extruded from the blown - die to process it into a thin - film form, and then it was cooled and wound up at a roll speed of 6.8 m / min to produce a film. The thickness of the produced film was 33 μm.

[0120] It was confirmed that the number of pinholes in the produced film was 1 piece / m 2 or less. Also, it was confirmed that no breakage occurred during the production of the film and the film could be stably formed.

[0121]

Table 1

[0122]

Table 2

[0123] [Example 2] It was manufactured in the same manner as in Example 1 above. At this time, except that the content of recycled polyethylene was adjusted to 95% by weight and the content of porous silica powder was adjusted to 5% by weight during the production of the recycled polyethylene compound composition, it was manufactured in the same manner as in Example 1.

[0124] The number of pinholes in the produced film was 1 piece / m 2 It was confirmed that it was as follows. Also, it was confirmed that no breakage occurred during the production of the film and that the film could be stably formed.

[0125] [Example 3] It was manufactured in the same manner as in Example 1 above. At this time, except that the content of recycled polyethylene was adjusted to 94% by weight and the content of porous silica powder was adjusted to 6% by weight during the production of the recycled polyethylene compound composition, it was manufactured in the same manner as in Example 1.

[0126] As a result, when the produced film was inspected, it was confirmed that the surface quality deteriorated due to the aggregation phenomenon of the silica powder. Also, as the content of the porous silica powder increased and the viscosity of the compound composition increased, the load on the film extruder increased, and an unstable phenomenon of the film bubble occurred.

[0127] [Example 4] It was manufactured in the same manner as in Example 1 above, except that 3% by weight of porous silica powder having the physical properties described in Table 3 below was mixed and used.

[0128] The number of pinholes in the produced film was 1 piece / m 2It was confirmed that the following was the case. Also, it was confirmed that no breakage occurred during the production of the film and that the film could be stably formed.

[0129]

Table 3

[0130] [Example 5] It was produced in the same manner as Example 1 except that 3% by weight of porous silica powder having the physical properties described in Table 4 below was mixed and used.

[0131] The number of pinholes in the produced film was 1 piece / m 2 It was confirmed that the following was the case. Also, it was confirmed that no breakage occurred during the production of the film and that the film could be stably formed.

[0132]

Table 4

[0133] [Example 6] It was produced in the same manner as Example 1 except that 3% by weight of porous silica powder having the physical properties described in Table 5 below was mixed and used.

[0134] The number of pinholes in the produced film was 1 piece / m 2 It was confirmed that the following was the case. Also, it was confirmed that no breakage occurred during the production of the film and that the film could be stably formed.

[0135]

Table 5

[0136] [Comparative Example 1] A recycled film was produced by using recycled polyethylene recovered from a separator of a secondary battery as a raw material without using porous silica powder in Example 1.

[0137] 70 wt% of recycled polyethylene recovered from the separator of a secondary battery and 30 wt% of virgin polyethylene resin (SK Geo Centric, YUZEX TM 8700) were used to produce a recycled film under the same conditions as in Example 1.

[0138] As a result, as shown in Fig. 3, it was confirmed that pinholes occurred.

[0139] [Comparative Example 2] It was manufactured in the same manner as in Example 1. At this time, when manufacturing the recycled polyethylene compound composition, porous silica powder was not added in powder form, and a masterbatch was manufactured and added.

[0140] That is, after manufacturing a masterbatch by compounding porous silica powder with polyethylene resin (SK Geo Centric, YUZEX TM 8700), it was added at a content such that the content of porous silica powder in the film became 3 wt% to produce a recycled polyethylene compound composition. Using this, as a result of manufacturing a film in the same manner as in Example 1, it was confirmed that a large number of pinholes occurred in the recycled film.

[0141] [Comparative Example 3] It was manufactured in the same manner as in Example 1, except that non-porous titanium dioxide particles with an average particle size of 5 μm were used instead of porous silica powder when manufacturing the recycled polyethylene compound composition.

[0142] As a result, it was confirmed that a large number of pinholes occurred in the recycled film.

[0143] The above content is merely an exemplification applying the principle of the present disclosure, and other configurations may be further included without departing from the scope of the present invention.

[0144] As described above, in the present invention, specific matters and limited embodiments are used for explanation, but this is provided for the purpose of helping a more general understanding of the present invention. The present invention is not limited to the above embodiments, and those having ordinary knowledge in the field to which the present invention pertains can make various modifications and deformations from such descriptions.

[0145] Therefore, the idea of the present invention should not be defined only by the above-described embodiments, and it can be said that not only the scope of the claims described later, but also all those having an equivalent or equivalent deformation to the scope of the present claims belong to the category of the idea of the present invention.

Claims

1. A recycled polyethylene compound composition comprising recycled polyethylene recovered from secondary battery separators and a porous powder.

2. The recycled polyethylene compound composition according to claim 1, wherein the recycled polyethylene is a powder obtained by crushing a separator as it is or a pellet obtained by melt-extrusion without removing a coating layer from the separator.

3. The recycled polyethylene compound composition of claim 1, wherein the recycled polyethylene has an inorganic particle content of 70% by weight or less.

4. The recycled polyethylene has a melt flow index of 5 g / 10 min or less measured at 2.16 kg and 190 ° C., and a density of 0.95 g / cm ３ The recycled polyethylene compound composition according to claim 1, wherein the weight average molecular weight is 50,000 g / mol or more.

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

6. The recycled polyethylene compound composition according to claim 1, wherein the recycled polyethylene contains a low molecular weight substance that is decomposed and exhibits a peak at a lower temperature than a polyethylene reference substance when measured using a thermogravimetric analyzer (TGA).

7. 7. The recycled polyethylene compound composition of claim 6, wherein the low molecular weight material is derived from a binder for a coating layer of a separator.

8. 8. The recycled polyethylene compound composition of claim 7, wherein the content of the low molecular weight substances is 3% by weight or less, based on the total weight of the recycled polyethylene.

9. The recycled polyethylene compound composition of claim 6, wherein the low molecular weight substance has a weight average molecular weight of 5000 g / mol or less.

10. The recycled polyethylene compound composition according to claim 1, wherein the porous powder is mixed at a content of 5% by weight or less.

11. The recycled polyethylene compound composition of claim 1, wherein the porous powder has an average particle size of 1 to 10 μm.

12. The recycled polyethylene compound composition according to claim 1, wherein the porous powder has an oil absorption of 50 to 150 cc / 100 g.

13. The recycled polyethylene compound composition of claim 1, wherein the porous powder has a pore volume of 0.1 to 1.0 ml / g.

14. The recycled polyethylene compound composition according to claim 1, wherein the porous powder is one or a mixture of two or more selected from the group consisting of porous silica, porous zeolite, and porous alumina.

15. A recycled polyethylene compound composition according to any one of claims 1 to 14, having a pinhole count of 1 / m ２ Below is the recycled film.

16. The recycled film according to claim 15, wherein the recycled polyethylene compound composition is pre-mixed with recycled polyethylene recovered from a separator of a secondary battery and a powder-like porous powder.

17. The recycled film of claim 15, further comprising a virgin polyolefin resin.

18. The recycled film of claim 17, comprising 60-90% by weight of recycled polyethylene compound composition and 10-40% by weight of virgin polyolefin resin.

19. The recycled film according to claim 15, having a thickness of 10 to 200 μm.

20. Pre-mixing the recycled polyethylene recovered from the separator of the secondary battery with the porous powder to prepare a recycled polyethylene compound composition; and melt-extruding the recycled polyethylene compound composition and a virgin polyolefin resin to produce a film.

21. In the step of producing the film, the recycled polyethylene compound composition and a virgin polyolefin resin are melt-extruded to produce pellets or dry-blended to produce a mixture; and melt extruding the pellets or mixture to produce a film.

22. The method for producing recycled films according to claim 20, wherein the pre-mixing is selected from the following (i) to (iii): (i) A method of dry blending recycled polyethylene in a powder or pellet state with a porous powder in a powder state; (ii) A method of simultaneously adding a fixed amount of recycled polyethylene in a powder or pellet state and a powder-state porous powder to a batch mixer and mixing them; (iii) A method comprising the step of feeding a porous powder in a powdered state by a side feeder of an extruder and mixing it with recycled polyethylene in a powdered or pelleted state.

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

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