Patent Description:
As the use of secondary batteries has been popularized, the number of secondary batteries that are discarded at the end of their life has also increased. Accordingly, various methods for recycling waste secondary batteries have been studied. For example, waste secondary batteries are collected and subjected to a pre-treatment operation including discharging, shredding, and sorting processes, such that external cans, separators, anodes/cathodes, and the like may be classified, and then metals such as cobalt, nickel, lithium, and manganese may be recovered.

However, a waste separator recovered from the waste secondary battery, a waste separator obtained from a defective secondary battery, or separator scrap generated in a manufacturing process is not recycled and is treated by inappropriate methods such as incineration or shredding and then taking it abroad, which is pointed out as a waste of resources and a cause of environmental pollution.

<CIT> discloses a method for preparing re-biological products from lead-acid battery polyethylene separator waste.

Accordingly, various efforts have been made to recycle the waste separators in order to solve the above problems, but since the physical properties and processability of the waste separator itself are insufficient, it is required to adjust the physical properties and processability of the waste separator to be suitable for the purpose and molding method.

In general, since a separator is formed of polyethylene, various products may be molded using the polyethylene recovered from the waste separator. Specifically, small products such as daily necessities may be manufactured or large products such as a water tank, playground equipment, and a vehicle frame may be manufactured. In particular, the large products are used in an external environment and are subjected to a high load for a long period of time, and thus should have excellent mechanical properties such as an environmental stress cracking resistance (ESCR) and an impact strength, a tensile strength, and a flexural modulus in a wide temperature range and should have excellent processability for efficient workability. However, the polyethylene recovered from the waste separator has an excellent impact strength in a wide temperature range, but has a poor environmental stress cracking resistance, an insufficient flexural modulus, and poor processability, and as a result, it is difficult to be molded.

Therefore, there is a need for developing an eco-friendly polymer composition that comprises polyethylene recycled from a waste separator, may be efficiently molded because it has excellent processability, and may implement excellent mechanical properties in a wide temperature range and an excellent environmental stress cracking resistance.

An embodiment of the present disclosure is directed to providing an eco-friendly polymer composition for manufacturing a large container that comprises high-density polyethylene recycled from a secondary battery separator, has excellent mechanical properties such as a flexural modulus and an impact strength in a wide temperature range, and has an excellent environmental stress cracking resistance.

Another embodiment of the present disclosure is directed to providing a large container manufactured by molding the polymer composition for manufacturing a large container.

Still another embodiment of the present disclosure is directed to providing a method of preparing a polymer composition having excellent processability and manufacturing a large container having excellent mechanical properties by molding the polymer composition by recycling a waste secondary battery separator.

A polymer composition for manufacturing a large container according to the invention comprises: a first high-density polyethylene recovered from a secondary battery separator; and a second high-density polyethylene having a density of <NUM> to <NUM>/cm<NUM> and a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>). The melt flow index (MFI) as referred to herein is as measured according to ASTM D1238. Whenever reference is made to a determination under conditions of <NUM> and <NUM>, the term high load melt index (HLMI) may synonymously be used.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the secondary battery separator may be one or two or more waste separators selected from a waste separator obtained by removing an inorganic coating layer from a separator recovered from a waste lithium secondary battery or a defective secondary battery, scrap generated in a secondary battery separator manufacturing process, and a separator distal end recovered after being trimmed.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the first high-density polyethylene recovered from the secondary battery separator may have a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>).

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the first high-density polyethylene recovered from the secondary battery separator may have a flexural modulus of <NUM>,<NUM> to <NUM>,<NUM>/cm<NUM>, a yield strength of <NUM> to <NUM>/cm<NUM>, a tensile strength of <NUM> to <NUM>/cm<NUM>, and an elongation of <NUM>% or more.

According to the invention, the first high-density polyethylene recovered from the secondary battery separator has a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>).

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may contain <NUM> to <NUM> wt% of the first high-density polyethylene recovered from the secondary battery separator and <NUM> to <NUM> wt% of the second high-density polyethylene, and preferably, may contain <NUM> to <NUM> wt% of the first high-density polyethylene recovered from the secondary battery separator and <NUM> to <NUM> wt% of the second high-density polyethylene.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the melt flow index MFI<NUM> of the first high-density polyethylene and the melt flow index MFI<NUM> of the second high-density polyethylene may satisfy the following Expression <NUM>, and the melt flow index may be measured according to ASTM D1238 (<NUM>, <NUM>),<MAT>.

[Expression <NUM>] <NUM> ≤ MFI<NUM> - MFI<NUM> ≤ <NUM>.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the second high-density polyethylene may have a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>).

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the second high-density polyethylene may have a room-temperature Izod impact strength of <NUM> kgf. cm/cm or less when measured at <NUM>.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the second high-density polyethylene may have a flexural modulus of <NUM>,<NUM>/cm<NUM> or more.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the second high-density polyethylene may have a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>), and a room-temperature Izod impact strength of <NUM> kgf. cm/cm or less when measured at <NUM>.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the second high-density polyethylene may have a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>), and a flexural modulus of <NUM>,<NUM>/cm<NUM> or more.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the second high-density polyethylene may have a room-temperature Izod impact strength of <NUM> kgf. cm/cm or less when measured at <NUM>, and a flexural modulus of <NUM>,<NUM>/cm<NUM> or more.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the second high-density polyethylene may have a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>), and a room-temperature Izod impact strength of <NUM> kgf. cm/cm or less when measured at <NUM>, and a flexural modulus of <NUM>,<NUM>/cm<NUM> or more.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may have a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>).

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may have a yield strength of <NUM>/cm<NUM> or more, a tensile strength of <NUM>/cm<NUM> or more, and an elongation of <NUM>,<NUM>% or more.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may have a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>), and a yield strength of <NUM>/cm<NUM> or more, a tensile strength of <NUM>/cm<NUM> or more, and an elongation of <NUM>,<NUM>% or more.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may satisfy the following conditions (<NUM>) and (<NUM>):
<MAT>
<MAT>
in the conditions (<NUM>) and (<NUM>), IZa is an Izod impact strength (kgf. cm/cm) measured at a temperature of a ± <NUM>, a is a real number, and ESCR is an environmental stress cracking resistance (time) measured according to ASTM D1693.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may have IZ<NUM> and IZ-<NUM> independently of each other of <NUM> kgf. cm/cm or more and a flexural modulus of <NUM>,<NUM>/cm<NUM> or more, where IZa is an Izod impact strength (kgf. cm/cm) measured at a temperature of a ± <NUM>, and a is a real number.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may satisfy the following conditions (<NUM>) and (<NUM>), and have IZ<NUM> and IZ-<NUM> independently of each other of <NUM> kgf. cm/cm or more and a flexural modulus of <NUM>,<NUM>/cm<NUM> or more, where IZa is an Izod impact strength (kgf. cm/cm) measured at a temperature of a ± <NUM>, and a is a real number. <MAT><MAT>
in the conditions (<NUM>) and (<NUM>), IZa is an Izod impact strength (kgf. cm/cm) measured at a temperature of a ± <NUM>, a is a real number, and ESCR is an environmental stress cracking resistance (time) measured according to ASTM D1693.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may contain x wt% of the first high-density polyethylene and y wt% of the second high-density polyethylene and may satisfy the following Expression <NUM>:<MAT>
in Expression <NUM>, E<NUM> is an elongation of the first high-density polyethylene, E<NUM> is an elongation of the second high-density polyethylene, E<NUM> is an elongation of the polymer composition for manufacturing a large container, and each of x and y is a real number equal to or greater than <NUM>.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may contain x wt% of the first high-density polyethylene and y wt% of the second high-density polyethylene and may satisfy the following Expression <NUM>:<MAT>
in Expression <NUM>, FM<NUM> is a flexural modulus of the first high-density polyethylene, FM<NUM> is a flexural modulus of the second high-density polyethylene, FM<NUM> is a flexural modulus of the polymer composition for manufacturing a large container, and each of x and y is a real number equal to or greater than <NUM>.

The invention further relates to a large container manufactured by molding the polymer composition according to the invention.

Yet further, the invention relates to a method of manufacturing a large container by recycling a waste secondary battery separator, the method comprising:.

In the method of manufacturing a large container by recycling a waste secondary battery separator according to an exemplary embodiment, the secondary battery separator in the step (a) may be one or two or more waste separators selected from a waste separator obtained by removing an inorganic coating layer from a separator recovered from a waste lithium secondary battery or a defective secondary battery, scrap generated in a secondary battery separator manufacturing process, and a separator distal end recovered after being trimmed.

In the method of manufacturing a large container by recycling a waste secondary battery separator according to an exemplary embodiment, the molding in the step (c) may be performed by injection molding, blow molding, extrusion molding, or rotational molding.

Hereinafter, the present disclosure will be described in more detail.

Units used in the present specification without special mention are based on weight, and as an example, a unit of % or a ratio means wt% or a weight ratio. Unless otherwise defined, wt% means wt% of any one component in a composition with respect to the total weight of the composition.

The term "large container" used in the present specification means a large industrial/building structure having a capacity of <NUM> or more, such as a large drum, fuel tank, water tank, transport pallet, or a floating structure for floating photovoltaic power generation, and specifically, may include a large structure having a volume of <NUM><NUM> or more, but is not limited thereto.

The present invention relates to a polymer composition for manufacturing a large container, the polymer composition comprising: a first high-density polyethylene recovered from a secondary battery separator; and a second high-density polyethylene having a density of <NUM> to <NUM>/cm<NUM> and a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>).

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the secondary battery separator may be one or two or more waste separators selected from a separator recovered from a waste lithium secondary battery, a separator recovered from a defective secondary battery, separator scrap generated in a secondary battery separator manufacturing process, and a separator distal end recovered after being trimmed. The first high-density polyethylene recovered from the secondary battery separator (hereinafter, referred to as first high-density polyethylene) is difficult to recycle because it has insufficient processability or insufficient mechanical properties such as a flexural modulus and an environmental stress cracking resistance. However, the polymer composition for manufacturing a large container according to an exemplary embodiment may effectively implement excellent processability and mechanical strength despite containing the first high-density polyethylene.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the first high-density polyethylene may have a weight average molecular weight (Mw) of <NUM>,<NUM> to <NUM>,<NUM>,<NUM>/mol, specifically, <NUM>,<NUM> to <NUM>,<NUM>,<NUM>/mol, and more specifically, <NUM>,<NUM> to <NUM>,<NUM>,<NUM>/mol, a number average molecular weight (Mn) of <NUM>,<NUM> to <NUM>,<NUM>,<NUM>/mol, specifically, <NUM>,<NUM> to <NUM>,<NUM>/mol, and more specifically, <NUM>,<NUM> to <NUM>,<NUM>/mol, and a polydispersity index (PDI) of <NUM> to <NUM>, specifically, <NUM> to <NUM>, and more specifically, <NUM> to <NUM>, but the first high-density polyethylene is not limited thereto, as long as it is first high-density polyethylene recovered from the secondary battery separator described above.

According to the invention, the first high-density polyethylene has a melt flow index of <NUM> to <NUM>/<NUM>, and may preferably have a melt flow index of <NUM> to <NUM>/<NUM>, when measured according to ASTM D1238 (<NUM>, <NUM>). The polymer composition according to the invention implements a melt flow index suitable for manufacturing a large container despite containing the first high-density polyethylene having a high load melt index within the above range.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a density of the first high-density polyethylene may be <NUM> to <NUM>/cm<NUM>, specifically, <NUM> to <NUM>/cm<NUM>, and more specifically, <NUM> to <NUM>/cm<NUM>.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a melting point (Tm) of the first high-density polyethylene may be <NUM> or higher, specifically, <NUM> or higher, and more specifically, <NUM> to <NUM>, but is not limited thereto.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a yield strength of the first high-density polyethylene may be <NUM> to <NUM>/cm<NUM>, specifically, <NUM> to <NUM>/cm<NUM>, and more specifically, <NUM> to <NUM>/cm<NUM>, but is not limited thereto.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a tensile strength of the first high-density polyethylene may be <NUM> to <NUM>/cm<NUM>, specifically, <NUM> to <NUM>/cm<NUM>, and more specifically, <NUM> to <NUM>/cm<NUM>, but is not limited thereto.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, an elongation at break of the first high-density polyethylene may be <NUM>% or more, <NUM> to <NUM>,<NUM>%, specifically, <NUM> to <NUM>,<NUM>%, and more specifically, <NUM> to <NUM>,<NUM>%, but is not limited thereto.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the first high-density polyethylene recovered from the secondary battery separator may have a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>) and a flexural modulus of <NUM>,<NUM> to <NUM>,<NUM>/cm<NUM>, a yield strength of <NUM> to <NUM>/cm<NUM>, a tensile strength of <NUM> to <NUM>/cm<NUM>, and an elongation of <NUM>% or more. Since the description of the melt flow index, the flexural modulus, the yield strength and the elongation are as described above, they will be omitted.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a room-temperature Izod impact strength (IZ<NUM>) of the first high-density polyethylene may be <NUM> kgf. cm/cm or more, and specifically, <NUM> kgf. cm/cm or more. In addition, a low-temperature Izod impact strength (IZ-<NUM>) may be <NUM> kgf. cm/cm or more, and specifically, <NUM> kgf. cm/cm or more, and upper limits of the room-temperature Izod impact strength (IZ<NUM>) and the low-temperature Izod impact strength (IZ-<NUM>) are not particularly limited, but may be each independently <NUM>,<NUM> kgf. cm/cm or less, where IZa is an Izod impact strength (kgf. cm/cm) measured at a temperature of a ± <NUM>, and a is a real number of -<NUM> to <NUM>. In the case of the polymer composition for manufacturing a large container comprising the first high-density polyethylene satisfying the above ranges, an excellent Izod impact strength may be exhibited, and in particular, a low-temperature Izod impact strength measured at sub-zero temperatures may be more significantly improved.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a flexural modulus of the first high-density polyethylene may be <NUM>,<NUM> to <NUM>,<NUM>/cm<NUM>, specifically, <NUM>,<NUM> to <NUM>,<NUM>/cm<NUM>, and more specifically, <NUM>,<NUM> to <NUM>,<NUM>/cm<NUM>.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, an environmental stress cracking resistance (ESCR) of the first high-density polyethylene may be <NUM> hours or shorter, specifically, <NUM> hours or shorter, and more specifically, <NUM> to <NUM> hours. High-density polyethylene recovered from a common secondary battery separator is not suitable for manufacturing a large container due to an insufficient environmental stress cracking resistance. However, the polymer composition according to an exemplary embodiment comprises the first high-density polyethylene and the second high-density polyethylene satisfying the physical properties described above in the above content ranges, such that a large container having an excellent environmental stress cracking resistance may be manufactured.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the second high-density polyethylene may have a weight average molecular weight (Mw) of <NUM>,<NUM> to <NUM>,<NUM>,<NUM>/mol, specifically, <NUM>,<NUM> to <NUM>,<NUM>,<NUM>/mol, and more specifically, <NUM>,<NUM> to <NUM>,<NUM>,<NUM>/mol, a number average molecular weight (Mn) of <NUM>,<NUM> to <NUM>,<NUM>,<NUM>/mol, specifically, <NUM>,<NUM> to <NUM>,<NUM>,<NUM>/mol, and more specifically, <NUM>,<NUM> to <NUM>,<NUM>,<NUM>/mol, and a polydispersity index (PDI) of <NUM> to <NUM>, and specifically, <NUM> to <NUM>, but the second high-density polyethylene is not limited thereto, and a commercially available product may be used.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the melt flow index MFI<NUM> of the first high-density polyethylene and the melt flow index MFI<NUM> of the second high-density polyethylene may satisfy the following Expression <NUM>, and specifically, the following Expression <NUM>. Here, the melt flow index is measured according to ASTM D1238 (<NUM>, <NUM>). <MAT><MAT>.

The polymer composition comprising the first high-density polyethylene and the second high-density polyethylene satisfying Expression <NUM>, and specifically, Expression <NUM>, may exhibit a melt flow index suitable for manufacturing a large container, thereby implementing improved work efficiency and a low defect rate.

In addition, the second high-density polyethylene is not particularly limited as long as the melt flow index measured according to ASTM D1238 (<NUM>, <NUM>) satisfies Expression <NUM>, and the melt flow index of the second high-density polyethylene may be specifically, <NUM> to <NUM>/<NUM>, more specifically, <NUM> to <NUM>/<NUM>, and still more specifically, <NUM> to <NUM>/<NUM> or <NUM> to <NUM>/<NUM>.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a density of the second high-density polyethylene may be <NUM> to <NUM>/cm<NUM>, specifically, <NUM> to <NUM>/cm<NUM>, and more specifically, <NUM> to <NUM>/cm<NUM>.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a melting point (Tm) of the second high-density polyethylene may be <NUM> or higher, specifically, <NUM> or higher, and more specifically, <NUM> to <NUM>, but is not limited thereto.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a yield strength of the second high-density polyethylene may be <NUM> to <NUM>/cm<NUM>, specifically, <NUM> to <NUM>/cm<NUM>, and more specifically, <NUM> to <NUM>/cm<NUM>, but is not limited thereto.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a tensile strength of the second high-density polyethylene may be <NUM> to <NUM>/cm<NUM>, specifically, <NUM> to <NUM>/cm<NUM>, and more specifically, <NUM> to <NUM>/cm<NUM>, but is not limited thereto.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, an elongation at break of the second high-density polyethylene may be <NUM> to <NUM>,<NUM>%, specifically, <NUM> to <NUM>,<NUM>%, and more specifically, <NUM> to <NUM>,<NUM> %, but is not limited thereto.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a room-temperature Izod impact strength (IZ<NUM>) of the second high-density polyethylene may be <NUM> kgf. cm/cm or more, and specifically, <NUM> to <NUM> kgf. In addition, a low-temperature Izod impact strength (IZ-<NUM>) of the second high-density polyethylene may be <NUM> kgf. cm/cm or more, and specifically, <NUM> to <NUM> kgf. cm/cm, where IZa is an Izod impact strength (kgf. cm/cm) measured at a temperature of a ± <NUM>, and a is a real number of -<NUM> to <NUM>. The second high-density polyethylene satisfying the above ranges exhibits a relatively insufficient Izod impact strength. However, the second high-density polyethylene is contained in the polymer composition for manufacturing a large container together with the first high-density polyethylene, such that an excellent Izod impact strength may be exhibited, and in particular, a low-temperature Izod impact strength measured at sub-zero temperatures may be more significantly improved.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a flexural modulus of the second high-density polyethylene may be <NUM>,<NUM> to <NUM>,<NUM>/cm<NUM>, specifically, <NUM>,<NUM> to <NUM>,<NUM>/cm<NUM>, and more specifically, <NUM>,<NUM> to <NUM>,<NUM>/cm<NUM> or <NUM>,<NUM>/cm<NUM> or more.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the second high-density polyethylene may have a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>), and a room-temperature Izod impact strength of <NUM> kgf. cm/cm or less when measured at <NUM>. Since the description of the melt flow index and the room-temperature Izod impact strength are as described above, they will be omitted.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the second high-density polyethylene may have a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>), and a flexural modulus of <NUM>,<NUM>/cm<NUM> or more. Since the description of the melt flow index and the flexural modulus are as described above, they will be omitted.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the second high-density polyethylene may have a room-temperature Izod impact strength of <NUM> kgf. cm/cm or less when measured at <NUM>, and a flexural modulus of <NUM>,<NUM>/cm<NUM> or more. Since the description of the room-temperature Izod impact strength and the flexural modulus are as described above, they will be omitted.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the second high-density polyethylene may have a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>), and a room-temperature Izod impact strength of <NUM> kgf. cm/cm or less when measured at <NUM>, and a flexural modulus of <NUM>,<NUM>/cm<NUM> or more. Since the description of the melt flow index, the room-temperature Izod impact strength and the flexural modulus are as described above, they will be omitted.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, an environmental stress cracking resistance (ESCR) of the second high-density polyethylene may be <NUM> hours or longer, specifically, <NUM> hours or longer, and more specifically, <NUM>,<NUM> hours or longer, but an upper limit thereof is not particularly limited.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, in the case of the polymer composition for manufacturing a large container comprising the second high-density polyethylene satisfying the physical properties described above, excellent process stability may be implemented because generation of fine powder or fumes is suppressed, and a melt flow index suitable for manufacturing a large container is exhibited despite containing a significant amount of the first high-density polyethylene recovered from the waste separator, such that work efficiency may be further improved, and an eco-friendly large container having excellent mechanical properties such as an elongation and a flexural modulus may be manufactured.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may contain <NUM> to <NUM> wt% of the first high-density polyethylene and <NUM> to <NUM> wt% of the second high-density polyethylene, and preferably, may contain <NUM> to <NUM> wt% of the first high-density polyethylene and <NUM> to <NUM> wt% of the second high-density polyethylene. When the above ranges are satisfied, work efficiency may be excellent because a melt flow index suitable for manufacturing a large container is exhibited, and generation of fine powder or fumes is reduced, such that excellent process stability may be implemented, and a large container having more excellent mechanical properties such as an Izod impact strength, an elongation, and a flexural modulus may be manufactured. Furthermore, as the content of the first high-density polyethylene is increased, recycling efficiency is increased, such that eco-friendliness may be more effectively implemented.

Specifically, the polymer composition for manufacturing a large container according to an exemplary embodiment exhibits a melt flow index suitable for manufacturing a large container despite comprising <NUM> wt% or more of the first high-density polyethylene recovered from the secondary battery separator, such that excellent work efficiency may be exhibited, and a large container having excellent mechanical properties such as an Izod impact strength, an elongation, and a flexural modulus may be manufactured, and eco-friendliness may be more effectively implemented because the polymer composition for manufacturing a large container according to an exemplary embodiment comprises <NUM> wt% or more of the recycled high-density polyethylene.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a density of the polymer composition for manufacturing a large container may be <NUM> to <NUM>/cm<NUM>, specifically, <NUM> to <NUM>/cm<NUM>, and more specifically, <NUM> to <NUM>/cm<NUM>. The polymer composition for manufacturing a large container may be used for manufacturing a floating structure (buoyant body) because it has a lower density than water.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may have a melt flow index of <NUM> to <NUM>/<NUM>, specifically, <NUM> to <NUM>/<NUM>, and more specifically, <NUM> to <NUM>/<NUM>, when measured according to ASTM D1238 (<NUM>, <NUM>). When the above range is satisfied, appropriate processability is imparted to a large container manufacturing process, such that further improved work efficiency and a lower defect rate may be implemented.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a yield strength and a tensile strength of the polymer composition for manufacturing a large container may be each independently <NUM>/cm<NUM> or more, specifically, <NUM>/cm<NUM> or more, and more specifically, <NUM>/cm<NUM> or more or <NUM>/cm<NUM> or more, and an upper limit thereof is not particularly limited, but may be <NUM>,<NUM>/cm<NUM> or less, and an elongation at break of the polymer composition for manufacturing a large container may be <NUM>% or more, specifically, <NUM>% or more, and more specifically, <NUM>,<NUM>% or more, and an upper limit thereof is not particularly limited, but may be <NUM>,<NUM>% or less.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the yield strength and the tensile strength of the polymer composition for manufacturing a large container may be each independently <NUM> to <NUM>,<NUM>/cm<NUM>, specifically, <NUM> to <NUM>/cm<NUM>, and more specifically, <NUM> to <NUM>/cm<NUM> or <NUM> to <NUM>/cm<NUM>, and the elongation at break of the polymer composition for manufacturing a large container may be <NUM> to <NUM>,<NUM>%, specifically, <NUM> to <NUM>,<NUM>%, and more specifically, <NUM>,<NUM> to <NUM>,<NUM>%.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may have a melt flow index of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>), and a yield strength of <NUM>/cm<NUM> or more, a tensile strength of <NUM>/cm<NUM> or more, and an elongation of <NUM>,<NUM>% or more. Since the description of the melt flow index, the yield strength, the tensile strength and the elongation are as described above, they will be omitted.

In the polymer composition for manufacturing a large container comprising x wt% of the first high-density polyethylene and y wt% of the second high-density polyethylene, a relationship between the elongation E<NUM> of the first high-density polyethylene, the elongation E<NUM> of the second high-density polyethylene, and the elongation E<NUM> of the polymer composition for manufacturing a large container may satisfy the following Expression <NUM>, and specifically, the following Expression <NUM>:
<MAT>
<MAT>.

The polymer composition for manufacturing a large container according to an exemplary embodiment comprises a combination of the first high-density polyethylene and the second high-density polyethylene, such that Expression <NUM>, and specifically, Expression <NUM>, may be satisfied, thereby exhibiting a better elongation than expected.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may have IZ<NUM> and IZ-<NUM> independently of each other of <NUM> kgf. cm/cm or more or <NUM> to <NUM> kgf. Specifically, IZ<NUM> may be <NUM> to <NUM> kgf. cm/cm or more, and more specifically, <NUM> to <NUM> kgf. cm/cm, and IZ-<NUM> may be <NUM> to <NUM> kgf. cm/cm or more, and more specifically, <NUM> to <NUM> kgf. In addition, IZ<NUM> and IZ-<NUM> may simultaneously satisfy the above ranges, but are not limited thereto, where IZa is an Izod impact strength (kgf. cm/cm) measured at a temperature of a ± <NUM>, and a is a real number of -<NUM> to <NUM>.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, an environmental stress cracking resistance (ESCR) of the polymer composition for manufacturing a large container may be <NUM> hours or longer, specifically, <NUM> hours or longer, and more specifically, <NUM>,<NUM> hours or longer, and an upper limit thereof is not particularly limited. The polymer composition according to an exemplary embodiment may implement an excellent environmental stress cracking resistance (ESCR) despite comprising the high-density polyethylene recovered from the secondary battery separator that has an insufficient environmental stress cracking resistance (ESCR).

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may satisfy the following conditions (<NUM>) and (<NUM>), and specifically, the following conditions (<NUM>) and (<NUM>):
<MAT>
<MAT>
<MAT>
in the conditions (<NUM>) to (<NUM>), IZa is an Izod impact strength (kgf. cm/cm) measured at a temperature of a ± <NUM>, a is a real number, and ESCR is an environmental stress cracking resistance (time) measured according to ASTM D1693.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, a flexural modulus of the polymer composition for manufacturing a large container may be <NUM>,<NUM>/cm<NUM> or more, specifically, <NUM>,<NUM>/cm<NUM> or more, and more specifically, <NUM>,<NUM>/cm<NUM> or more, and an upper limited thereof is not particularly limited, but may be <NUM>,<NUM>/cm<NUM> or less.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the flexural modulus of the polymer composition for manufacturing a large container may be <NUM>,<NUM> to <NUM>,<NUM>/cm<NUM>, specifically, <NUM>,<NUM> to <NUM>,<NUM>/cm<NUM>, and more specifically, <NUM>,<NUM> to <NUM>,<NUM>/cm<NUM>.

In the polymer composition for manufacturing a large container comprising x wt% of the first high-density polyethylene and y wt% of the second high-density polyethylene, a relationship between the flexural modulus FM<NUM> of the first high-density polyethylene, the flexural modulus FM<NUM> of the second high-density polyethylene, and the flexural modulus FM<NUM> of the polymer composition for manufacturing a large container may satisfy the following Expression <NUM>, and specifically, the following Expression <NUM>:
<MAT>
<MAT>.

The polymer composition for manufacturing a large container according to an exemplary embodiment comprises a combination of the first high-density polyethylene and the second high-density polyethylene, such that Expression <NUM>, and specifically, Expression <NUM>, may be satisfied, thereby exhibiting a better flexural modulus than expected.

In addition, in the polymer composition for manufacturing a large container comprising x wt% of the first high-density polyethylene and y wt% of the second high-density polyethylene, Expressions <NUM> and <NUM> may be simultaneously satisfied, and specifically, Expressions <NUM> and <NUM> may be simultaneously satisfied.

In addition, a relationship between the flexural modulus FM<NUM> of the first high-density polyethylene and the flexural modulus FM<NUM> of the polymer composition for manufacturing a large container may satisfy the following Expression <NUM>:<MAT>.

When Expression <NUM> is satisfied, it is possible to prepare a polymer composition for manufacturing a large container that has a further improved flexural modulus despite being manufactured using the first high-density polyethylene recovered from the secondary battery separator.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition for manufacturing a large container may satisfy the conditions (<NUM>) and (<NUM>), and have IZ<NUM> and IZ-<NUM> independently of each other of <NUM> kgf. cm/cm or more and a flexural modulus of <NUM>,<NUM>/cm<NUM> or more. Since the description of the conditions (<NUM>) and (<NUM>), IZ<NUM>, IZ-<NUM> and the flexural modulus are as described above, they will be omitted.

In the polymer composition for manufacturing a large container according to an exemplary embodiment, the polymer composition may further contain additives generally used in the art depending on the purpose and use. For example, the polymer composition may further contain an antioxidant, a UV absorber, a UV stabilizer, a lubricant, a pigment, a colorant, a filler, a plasticizer, a rheological agent, an antistatic agent, a flame retardant, a slip agent, an anti-block agent, and the like, and the additives may be contained in an appropriate amount within a range that does not impair the desired physical properties.

The UV absorber may be a benzotriazine-based or benzotriazole-based UV absorber, and may be further mixed with primary and secondary antioxidants such as dibutylhydroxytoluene, nonylphenyl phosphite, and dibutylmethylphenol, or HALS-based UV absorbers. The type and content thereof are not particularly limited as long as the desired physical properties are not impaired.

Non-limiting examples of the benzotriazole-based UV absorber include <NUM>-(<NUM>'-hydromethylphenyl)benzotriazole, <NUM>-(<NUM>'-hydroxy-<NUM>',<NUM>'-bis(α,α-dimethylbenzylphenyl))benzotriazole, <NUM>-(<NUM>'-hydroxy-<NUM>',<NUM>'-dibutylphenyl)benzotriazole, <NUM>-(<NUM>'-hydroxy-<NUM>'-tert-butyl-<NUM>'-methylphenyl)-<NUM>-chlorobenzotriazole, and <NUM>-(<NUM>'-hydroxy-<NUM>',<NUM>'-di-tert-butylphenyl)-<NUM>-chlorobenzotriazole, and examples of the benzotriazine-based UV absorber include bis-ethylhexyloxyphenol methoxyphenyl triazine, but are not limited thereto.

In addition, the lubricant serves to improve fluidity and suppress frictional heat during extrusion molding, and may be one or more combinations selected from hydrocarbon-based, carboxylic acid-based, alcohol-based, amide-based, and ester-based compounds, and mixtures thereof. The type and content thereof are not particularly limited as long as the desired physical properties are not impaired.

The present disclosure may provide pellets for molding comprising the polymer composition for manufacturing a large container. The pellet refers to a preform cut to a uniform size before manufacturing a molded article, and may be manufactured according to a common and known method such as extrusion and injection. In addition, the size and shape of the pellet are not limited, and the pellet may further contain commonly used or known additives.

The present disclosure may provide a large container manufactured by molding the polymer composition for manufacturing a large container. The molding may be a molding method commonly used to manufacture a large container or a known molding method, and for example, one or more selected from injection molding, blow molding, extrusion molding, and rotational molding may be used, but are not limited thereto. The polymer composition for manufacturing a large container according to an exemplary embodiment exhibits a melt flow index suitable for a large container molding method, such that efficient work may be implemented, and accordingly, a defect rate during work may be reduced.

In addition, the large container may be a molded article such as an interior/exterior material for a vehicle, a building material, a large-capacity drum, a transport pallet, a floating structure, or a large tank, but is not limited thereto. The large container according to an exemplary embodiment has excellent physical properties such as a tensile strength, a yield strength, an elongation, a flexural strength, a low-temperature impact strength, and ESCR, such that the large container is suitable for application to a large interior/exterior structure, and above all, has excellent eco-friendliness in terms of being manufactured by recycling the first high-density polyethylene recovered from the secondary battery separator.

Hereinafter, a method of manufacturing a large container by recycling a waste secondary battery separator according to an exemplary embodiment will be described in more detail.

The present disclosure provides a method of manufacturing a large container by recycling a waste secondary battery separator, the method comprising: (a) recovering first high-density polyethylene from a secondary battery separator and selecting second high-density polyethylene satisfying the following Expression <NUM>, and specifically, the following Expression <NUM>; (b) producing a preform using a polymer composition for manufacturing a large container comprising the first high-density polyethylene and the second high-density polyethylene; and (c) manufacturing a large container by molding the preform,.

In the method of manufacturing a large container by recycling a waste secondary battery separator according to an exemplary embodiment, the secondary battery separator in the step (a) may be one or two or more waste separators selected from a waste separator obtained by removing an inorganic coating layer from a separator recovered from a waste lithium secondary battery or a defective secondary battery, scrap generated in a secondary battery separator manufacturing process, and a separator distal end recovered after being trimmed. In addition, the step (a) may further include a chemical or physical pretreatment process according to a commonly used or known method in order to remove impurities other than the first high-density polyethylene from the secondary battery separator, but is not limited thereto.

The first high-density polyethylene recovered from the secondary battery separator and the second high-density polyethylene may be combined by mixing together, optionally with one or more of the additives described, herein common polymer processing methods such as solvent mixing, melt mixing, or melt mixing after introducing pellets into an extruder may be used, but are not limited thereto, and further processed by molding or by forming a preform as described below prior to molding.

In addition, specific descriptions of the first high-density polyethylene, the second high-density polyethylene, and the polymer composition for manufacturing a large container and examples of the compound are the same as those described above, and thus will be omitted.

In the step (a), selecting second high-density polyethylene satisfying Expression <NUM>, and specifically, Expression <NUM>, may be performed, and the selected second high-density polyethylene is contained, such that a polymer composition for manufacturing a large container having the physical properties described above may be prepared.

The large container or the polymer composition for manufacturing a large container according to an exemplary embodiment is environmentally friendly in terms of recycling the waste secondary battery separator described above, and furthermore, in the case of the first high-density polyethylene recovered from the secondary battery separator, a molding method is difficult and insufficient physical properties are exhibited, but in order to overcome these problems, the second high-density polyethylene selected based on specific conditions is contained, such that a large container having further improved processability and more excellent mechanical properties may be manufactured.

In the method of manufacturing a large container by recycling a waste secondary battery separator according to an exemplary embodiment, the step (b) is producing a preform for the molding in the step (c) using the polymer composition for manufacturing a large container. Specifically, the preform may be produced in the form of pellets for extrusion molding or injection molding or a parison for blow molding, but is not particularly limited as long as it is common or known.

In the method of manufacturing a large container by recycling a waste secondary battery separator according to an exemplary embodiment, the molding in the step (c) may be performed by injection molding, blow molding, extrusion molding, or rotational molding. The molding may be performed using any common or known method used to manufacture a large container without limitation. Although the polymer composition for manufacturing a large container according to an exemplary embodiment comprises the high-density polyethylene recovered from the secondary battery separator having insufficient physical properties and processability, the polymer composition also comprises the second high-density polyethylene selected according to specific conditions, such that processability suitable for manufacturing a large container and excellent physical properties may be exhibited.

Hereinafter, the present disclosure will be described in more detail with reference to Examples and Comparative Examples.

Physical properties in the following Examples and Comparative Examples were measured by the following methods.

Scrap generated in a secondary battery separator manufacturing process using high-density polyethylene as a raw material or a separator distal end sample recovered after being trimmed was pulverized into a size of <NUM> × <NUM> or less to obtain pellets through an extruder at a processing temperature of <NUM>, and the pellets were sufficiently dried, thereby obtaining first high-density polyethylene pellets. The physical properties were measured. The results are shown in Table <NUM>.

The polymer composition prepared according to Table <NUM> was injected into a twin-screw extruder and melt-extrusion was performed at a processing temperature of <NUM> for a sufficient time to obtain recycled resin pellets, and the recycled resin pellets were sufficiently dried and then melt-mixed with a virgin plastic resin at a processing temperature of <NUM> to prepare pellets for molding through an extruder. The pellets for molding were injected or extruded to prepare a specimen suitable for each physical property evaluation standard, and the physical properties of the specimen were measured. The results are shown in Table <NUM>.

It was confirmed from Tables <NUM> and <NUM> that since the first high-density polyethylene and the second high-density polyethylene were contained in the polymer composition according to each of Examples, a melt flow index preferred for manufacturing a large container was exhibited, and thus excellent processability was implemented, such that the manufactured molded article had an excellent low-temperature impact strength and an excellent flexural modulus and also had a significantly improved environmental stress cracking resistance compared to the first high-density polyethylene recovered from the secondary battery separator of Preparation Example <NUM>.

In particular, it was confirmed that in the cases of the polymer compositions for manufacturing a large container according to Examples <NUM> and <NUM>, despite comprising <NUM> wt% or more of the first high-density polyethylene recovered from the secondary battery separator, mechanical properties suitable for manufacturing a large container such as a melt flow index, an excellent Izod impact strength, an elongation, and a flexural modulus were exhibited, and eco-friendliness was more effectively implemented because <NUM> wt% or more of the recycled high-density polyethylene was contained.

In addition, from the fact that the physical properties of the product F used for manufacturing an actual large container, for example, a structure for a buoyant body, were equally similar to the physical properties of the polymer composition according to an exemplary embodiment, it was confirmed that in the case of the polymer composition according to an exemplary embodiment, a large container having excellent physical properties was manufactured by recycling the high-density polyethylene recovered from the waste secondary battery separator.

Claim 1:
A polymer composition for manufacturing a container having a capacity of <NUM> or more, the polymer composition comprising:
a first high-density polyethylene recovered from a secondary battery separator having a high load melt index (HLMI) of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>); and
a second high-density polyethylene having a density of <NUM> to <NUM>/cm<NUM> and a high load melt index (HLMI)of <NUM> to <NUM>/<NUM> when measured according to ASTM D1238 (<NUM>, <NUM>).