Casting machine for manufacturing stretch film

Abstract

The present invention relates to a method for manufacturing a stretch film made from waste raw materials, comprising the steps of: preparing waste raw materials; providing a stretch film manufacturing device; and The present invention provides a method for manufacturing a stretch film from waste raw materials and a stretch film produced thereby, comprising the step of manufacturing a stretch film from the waste raw materials using the stretch film manufacturing device described above, wherein the stretch film manufacturing device comprises: an extruder that melts the waste raw materials by heat and pressure and discharges them in the form of a molten film; a storage die that receives and injects the molten film discharged from the extruder; and a cooling device that cools the molten film passing through the storage die to form a stretch film, wherein the extruder includes an extrusion pipe for mixing and conveying the molten raw materials, and a spiral screw made of an alloy material is disposed inside the extrusion pipe.

Description

Technology Field

[0001] The present invention relates to a stretch film manufactured from waste raw materials and a method for manufacturing the same, and more specifically, to a stretch film manufactured from recycled raw materials using a casting device and a method for manufacturing the same. Background Technology

[0002] Stretch film is one of the packaging materials primarily used in the logistics industry. As a transparent material with high elasticity and strength, it is used to package items of various sizes and shapes. Stretch film is formed from raw materials mixed with polymer raw materials and additives, with linear low-density polyethylene being a representative example of the polymer raw material.

[0003] Polyethylene (PE), extracted from crude oil, is used as a basic raw material for plastics. Depending on its density, it can be classified into low-density polyethylene (LDPE) and high-density polyethylene (HDPE); linear low-density polyethylene (LLDPE) is used as a raw material for various industrial packaging materials and food packaging due to its good strength, plasticity, and excellent optical properties.

[0004] There is a casting method for manufacturing stretch film from linear low-density polyethylene raw materials, which is a method in which the raw materials are melted in an extruder and the molten film is cooled through a subsequent process to form a roll-shaped product.

[0005] Stretch films made from petroleum-based raw materials are causing environmental problems such as resource depletion, waste disposal issues, and carbon emissions.

[0006] Recently, there has been a growing need for technology to manufacture stretch films using waste materials as raw materials.

[0007] There is a demand for technology to manufacture stretch films using post-consumer recycled (PCR) raw materials or post-industrial recycled (PIR) materials.

[0008] In particular, when manufacturing stretch film using post-consumer waste (PCR) raw materials with a conventional casting device, there are problems such as defective products resulting from the inclusion of foreign substances or damage to the casting device. Prior art literature

[0009] Korean Registered Patent No. 10-1077257 (Date of Publication: Oct. 27, 2011) Korean Published Patent No. 10-2024-0079501 ​​(Date of Publication: June 5, 2020) The problem to be solved

[0010] To solve the above-mentioned problems, the purpose of the stretch film manufactured from waste raw materials and the method for manufacturing the same according to the present invention is as follows.

[0011] The objective of the present invention is to contribute to carbon neutrality, ESG management, waste reduction, and the establishment of a recycling circular ecosystem by providing a stretch film manufactured from post-consumer recycled (PCR) raw materials and a method for manufacturing the same.

[0012] Another objective of the present invention is to provide a method for manufacturing a foreign substance-free stretch film using post-consumer recycled (PCR) raw materials containing foreign substances. means of solving the problem

[0013] A method for manufacturing a stretch film from waste raw materials according to one embodiment of the present invention comprises: a step of preparing waste raw materials; a step of providing a stretch film manufacturing device; and a step of manufacturing a stretch film from said waste raw materials using said stretch film manufacturing device, wherein the stretch film manufacturing device comprises: an extruder that melts said waste raw materials by heat and pressure and discharges them in the form of a molten film; a storage die that receives and injects the molten film discharged from said extruder; and a cooling device that cools the molten film that has passed through said storage die to form a stretch film, and the extruder comprises an extrusion pipe for mixing and conveying the molten raw materials, and a spiral screw made of an alloy material is disposed inside said extrusion pipe.

[0014] The above waste raw material may be a post-consumer recycled (PCR) raw material.

[0015] The spiral screw above may be divided into a conveying section that conveys the molten film in the order of the direction in which the molten film is extruded, a compression section that compresses the molten film, and a metering section that discharges the molten film at a constant density.

[0016] The screw pitch of the above conveying section is wider than the pitch of the above compression section and the above metering section, and the pitch of the above compression section may gradually narrow as it moves in the direction of extrusion.

[0017] The height of the screw rotating blade may increase in the order of the conveying section, the metering section, and the compression section.

[0018] The depth of the screw groove may increase in the order of the conveying section, the compression section, and the metering section.

[0019] A filter for filtering out impurities from the molten film may be placed between the extrusion tube and the storage die.

[0020] The above filter is formed with a first filter section, a spacer, and a second filter section in the order of the direction in which the molten film is extruded, and

[0021] The first filter part is a nonwoven fabric produced by the melt-blown method, the second filter part is made of stainless steel, the pore size is 150 to 400 mesh, and the spacer can be formed of a non-filtered scrim material.

[0022] A first pressure sensor may be placed at the outlet of the storage die to measure the pressure of the molten film injected therein.

[0023] A second pressure sensor may be placed at the outlet of the extrusion tube to measure the pressure of the molten film injected therein.

[0024] The rotational speed of the screw can be adjusted based on the difference in pressure measured by the first pressure sensor and the second pressure sensor.

[0025] The apparatus further includes an injection tube for moving the molten film injected from the storage die, and the injection tube may be formed in the shape of a corrugated tube.

[0026] A stretch film manufactured from waste raw materials according to another embodiment of the present invention is a stretch film manufactured by a method for manufacturing a stretch film from waste raw materials according to an embodiment of the present invention. Effects of the invention

[0027] According to the present invention as described above, the following effects are achieved.

[0028] The present invention can produce the following effects through the above-mentioned solution means.

[0029] First, a stretch film free of foreign substances can be manufactured from waste raw materials using the stretch film manufacturing device according to the present invention.

[0030] Second, the screw according to the embodiment of the present invention is divided into a conveying section that conveys the molten film in the order of the molten film extrusion direction, a compression section that compresses the molten film, and a metering section that discharges the molten film at a constant density, and the height of the screw rotating blade formed in each section, the depth of the groove, and the length of the pitch section are formed differently so that each section can perform its function well.

[0031] Third, a filter according to one embodiment of the invention is formed by including a first filter section manufactured by a melt-blown method, a second filter section formed of stainless steel material to have pores of a certain size, and a spacer formed of a non-filtered scrim material between the first filter section and the second filter section, thereby enabling effective filtering of various foreign substances or unmelted waste plastics contained in the molten film and controlling the density of the molten film in mesh units.

[0032] Fourth, the present invention can maintain a constant extrusion amount by controlling the rotation speed of the screw when the extrusion amount of the extruder is not constant, by sensing the pressure change of the molten film through a first pressure sensor provided at the outlet of the storage die.

[0033] Fifth, the present invention includes a corrugated injection tube, so that while the molten film passes through the injection tube, residues containing foreign substances with a density greater than that of the pure raw material can settle at the bottom of the corrugated tube and be filtered out.

[0034] Sixth, the stretch film manufacturing device according to the present invention can manufacture a stretch film with excellent tensile strength by maintaining a constant extrusion amount of the molten film by adjusting the rotational speed of the screw according to waste raw materials containing various physical properties and foreign substances based on the difference in pressure measured by the first pressure sensor and the second pressure sensor. Brief explanation of the drawing

[0035] FIG. 1 is a schematic diagram illustrating the sequence of manufacturing a stretch film using waste raw materials according to an embodiment of the present invention. FIG. 2 is a drawing for explaining waste raw materials according to an embodiment of the present invention. FIG. 3 is a schematic diagram of a stretch film manufacturing apparatus according to one embodiment of the present invention. FIG. 4 is an enlarged view for illustrating a screw according to one embodiment of the present invention. FIG. 5 is a schematic diagram illustrating a filter according to one embodiment of the present invention. FIG. 6 is an enlarged view illustrating an injection tube according to an embodiment of the present invention. FIG. 7 is a schematic diagram of a stretch film manufacturing apparatus according to another embodiment of the present invention. FIG. 8 is a schematic diagram of a method for manufacturing a stretch film made from waste raw materials according to an embodiment of the present invention. Specific details for implementing the invention

[0036] It should be noted that in assigning reference numbers to the components of each drawing in this specification, identical components are given the same number as much as possible, even if they are shown in different drawings.

[0037] Meanwhile, the meaning of the terms described in this specification should be understood as follows.

[0038] A singular expression should be understood to include a plural expression unless the context clearly defines otherwise, and terms such as "first," "second," etc., are intended to distinguish one component from another, and the scope of rights shall not be limited by these terms.

[0039] Terms such as "include" or "have" should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0040] Hereinafter, preferred embodiments of the present invention designed to solve the above problems will be described in detail with reference to the attached drawings.

[0041] FIG. 1 is a schematic diagram illustrating the sequence of manufacturing a stretch film using waste raw materials according to an embodiment of the present invention, and FIG. 2 is a drawing illustrating waste raw materials according to an embodiment of the present invention.

[0042] Referring to FIG. 1, the present invention uses a stretch film manufacturing device (1000) to manufacture a stretch film (3000) from waste raw materials (2000).

[0043] The waste raw material (2000) used in the present invention may be a post-consumer recycled (PCR) raw material.

[0044] Post-consumer waste raw materials can be a mixture or compound of various wastes generated after consumer use, and there are problems such as higher contamination levels and inconsistent quality compared to petroleum-based raw materials or post-industrial recycled (PIR).

[0045] To solve this problem, a stretch film (3000) free of foreign substances can be manufactured from waste raw materials (2000) using a stretch film manufacturing device (1000) according to the present invention.

[0046] Referring to FIG. 2, the post-consumer recycled (PCR) raw material according to the present invention is shown, and it may vary depending on the place of demand where the raw material is used, the washing method, and the characteristics of the remaining impurities.

[0047] For example, the consumer post-consumer recycled (PCR) raw material (2100) according to the first embodiment is used in a manufacturing facility, has undergone three stages of washing, and contains organic compounds and metal impurities.

[0048] The consumer post-consumer recycled (PCR) raw material (2100) according to the first embodiment has a demand source where the raw material is used that is a manufacturing company, has undergone three stages of washing, and contains metal as an impurity.

[0049] The post-consumer recycled (PCR) raw material (2100) according to the second embodiment has a complex range of uses, has undergone simple washing, and contains other PE (polyethylene) other than HDPE, LDPE, and LLDPE as impurities.

[0050] According to the third embodiment, the consumer post-consumer recycled (PCR) raw material (2100) is used in the food industry, has undergone simple washing, and contains soil as an impurity.

[0051] According to the fourth embodiment, the consumer post-recycled (PCR) raw material (2100) is used in a manufacturing facility, has undergone three stages of washing, and contains metal as an impurity.

[0052] According to the fifth embodiment, the consumer post-consumer recycled (PCR) raw material (2100) is used in a manufacturing facility, has undergone steam cleaning, and contains soil as an impurity.

[0053] As such, the type and amount of foreign substances included in the waste raw material (2000) vary depending on the type of raw material, the place of use, the degree of washing, etc., and accordingly, physical properties such as density and melt index may vary.

[0054] Depending on these various waste materials (2000), the tensile strength, tensile elongation, transparency, etc. of the stretch film (3000) may vary.

[0055] That is, the present invention may use a stretch film manufacturing apparatus (1000) according to one embodiment of the present invention to manufacture a stretch film (3000) having a certain specification according to a waste raw material (2000) containing various physical properties and foreign substances.

[0056] FIG. 3 is a schematic diagram of a stretch film manufacturing apparatus according to one embodiment of the present invention, FIG. 4 is an enlarged view for explaining a screw according to one embodiment of the present invention, FIG. 5 is a schematic diagram for explaining a filter according to one embodiment of the present invention, and FIG. 6 is an enlarged view for explaining an injection tube according to an embodiment of the present invention.

[0057] Referring to FIG. 3, a stretch film manufacturing apparatus (1000) according to one embodiment of the present invention includes an extruder (100), a storage die (200), an injection tube (300), an air knife (400), and a cooling roller (500).

[0058] The extruder (100) can melt waste raw material fed through the raw material inlet (105) by heat and pressure. The molten film in the molten state can be discharged by passing through the extrusion pipe (110) and the transfer pipe (120).

[0059] FIG. 4 is an enlarged view of part a of the extrusion pipe, in which a spiral screw (115) made of alloy material is placed inside the extrusion pipe (110) to evenly mix the input raw material.

[0060] A screw (115) according to one embodiment of the present invention is formed using an aluminum-based alloy material, thereby reducing the risk of damage to the screw by foreign substances compared to when a steel material is used, and can maintain a constant degree of melting even with torque interference due to the density of the raw material.

[0061] The screw (115) according to an embodiment of the present invention may be divided into a conveying section (A) for conveying the molten film in the order of the molten film being extruded, a compression section (B) for compressing the molten film, and a metering section (C) for discharging the molten film at a constant density.

[0062] According to one embodiment of the present invention, the screw (115) is formed such that the screw pitch (L) of the conveying section (A) is wider than the pitch of the compression section (B) and the metering section (C), and the pitch (L) of the compression section (B) becomes progressively narrower as it moves toward the extrusion direction, thereby enabling each section to perform its function well.

[0063] According to another embodiment of the present invention, the height (H) of the screw (115) rotating blade is formed to be large in the order of the conveying section (A), the metering section (C), and the compression section (B), so that the function of each section can be performed well.

[0064] According to another embodiment of the present invention, the depth (D) of the screw (115) groove is formed in the order of the conveying section (A), the compression section (B), and the metering section (C), so that each section can perform its function well.

[0065] As such, the screw (115) according to the embodiment of the present invention is divided into a conveying section (A) for conveying the molten film in the order of the molten film extrusion direction, a compression section (B) for compressing the molten film, and a metering section (C) for discharging the molten film at a constant density, and the height of the screw rotating blade formed in each section, the depth of the groove, and the length of the pitch section are formed differently so that the function of each section can be performed well.

[0066] The storage die (200) functions to receive the molten film discharged from the extruder (100) and inject a certain amount. The molten raw material may contain foreign substances or uneven raw material generated during the recycling process, and a filter (210) may be placed between the extrusion pipe (110) and the storage die (200) to filter these out.

[0067] Referring to FIG. 5, a filter (210) according to one embodiment of the present invention may be formed with a first filter section (211), a spacer (213), and a second filter section (215) in the order of the direction in which the molten film is extruded.

[0068] The first filter section (211) can be formed using a material such as a non-woven fabric produced by a melt-blown method. The second filter section (215) can be formed using stainless steel material to have pores of a size of 150 to 400 mesh. The spacer (213) can be formed from a non-filtering scrim material.

[0069] A filter (210) according to one embodiment of the present invention, as described above, comprises a first filter section manufactured by a melt-blown method, a second filter section formed of stainless steel material to have pores of a certain size, and a spacer formed of a non-filtered scrim material between the first filter section and the second filter section, thereby effectively filtering various foreign substances or unmelted waste plastic contained in the molten film and controlling the density of the molten film in mesh units.

[0070] A first pressure sensor (230) for measuring the pressure of the molten film being injected may be placed at the exit of the storage die (200).

[0071] By sensing the pressure change of the molten film through the first pressure sensor (230), if the extrusion amount of the extruder is not constant, the rotation speed of the screw can be controlled to maintain a constant extrusion amount.

[0072] A stretch film manufacturing device (1000) according to one embodiment of the present invention may further include an injection tube (300) for moving a molten film injected from a storage die (200).

[0073] Referring to FIG. 6, an injection tube (300) according to one embodiment of the present invention may be formed in the shape of a corrugated tube.

[0074] The injection tube (300) can serve as a passage for moving the molten film injected from the storage die to the cooling device. The tube may have a structure in which the diameter of the tube changes periodically in the direction of travel of the molten film. In the molten film, there is a difference in density between the pure raw material and the foreign material, and the residue (310) containing the foreign material, which has a higher density than the pure raw material, can be filtered out by settling at the bottom of the corrugated tube while the molten film passes through the injection tube.

[0075] A stretch film manufacturing device (1000) according to one embodiment of the present invention may include an oni (400) and a cooling roller (500).

[0076] In order to form the final product, a stretch film, from the molten film, a cooling process is required, and an air knife (400) and a cooling roller (500) can serve as cooling devices.

[0077] The air knife (400) cools the molten film by amplifying compressed air and spraying it uniformly, and the cooling roller (500) can further cool the film that has passed through the film passage (600) using the internal refrigerant.

[0078] A stretch film manufacturing device according to another embodiment of the present invention may have a second pressure sensor disposed therein for measuring the pressure of a molten film injected at the outlet of an extrusion tube.

[0079] FIG. 7 is a schematic diagram of a stretch film manufacturing apparatus according to another embodiment of the present invention.

[0080] Referring to FIG. 7, a stretch film manufacturing device (1100) according to another embodiment of the present invention may have a first pressure sensor (230) for measuring the pressure of a molten film injected at the outlet of a storage die (200), and a second pressure sensor (231) for measuring the pressure of a molten film injected at the outlet of an extrusion pipe (110).

[0081] A stretch film manufacturing device (1100) according to another embodiment of the present invention can form a stretch film with excellent tensile strength by maintaining a constant extrusion amount of a molten film by adjusting the rotational speed of a screw according to a waste raw material (2000) containing various physical properties and foreign substances based on the difference in pressure measured by a first pressure sensor (230) and a second pressure sensor (231).

[0082] FIG. 8 is a schematic diagram of a method for manufacturing a stretch film made from waste raw materials according to an embodiment of the present invention.

[0083] Referring to FIG. 8, a method for manufacturing a stretch film made from waste raw materials according to an embodiment of the present invention includes the steps of preparing waste raw materials (S100), providing a stretch film manufacturing device (S200), and manufacturing a stretch film (S300).

[0084] In this case, the type and amount of foreign substances contained in the waste raw material vary depending on the type of raw material, the destination of use, and the degree of washing, and accordingly, physical properties such as density and melt index may vary.

[0085] Depending on these various waste materials, the tensile strength, tensile elongation, and transparency of the stretch film may vary.

[0086] A method for manufacturing a stretch film from waste raw materials according to an embodiment of the present invention can provide a stretch film manufacturing apparatus for manufacturing a stretch film having a desired specification from various waste raw materials.

[0087] The stretch film manufacturing device according to this may include the various components described above.

[0088] The invention described above has been explained with reference to the embodiments illustrated in the drawings, but this is merely illustrative, and it is made clear that various modifications and equivalent alternative embodiments are possible therefrom for those skilled in the art.

[0089] Unless there is an explicit description of the order of the steps constituting the method according to the present invention or a description contrary to it, said steps may be performed in a suitable order. The present invention is not necessarily limited to the order in which said steps are described.

[0090] The use of all examples or exemplary terms (e.g., etc.) in the present invention is merely for the purpose of describing the invention in detail, and the scope of the invention is not limited by such examples or exemplary terms unless limited by the claims. Furthermore, a person skilled in the art will understand that various modifications, combinations, and changes may be made according to design conditions and factors within the scope of the claims or equivalents to which they are added.

[0091] It will be obvious to those skilled in the art that the present invention described above is not limited to the aforementioned embodiments and attached drawings, and that various substitutions, modifications, and changes are possible within the scope of the technical concept of the present invention. Explanation of the symbols

[0092] 100: Extruder 110: Extrusion pipe 115: Screw 200: Storage Die 210: Filter 211: First filter section 213: Spacer 215: Second filter section 230: 1st pressure sensor 231: 2nd pressure sensor 300: Injection tube 400: Air knife 500: Cooling roller

Claims

Claim 1 A method for manufacturing a stretch film made from waste raw materials comprises: a step of preparing waste raw materials; a step of providing a stretch film manufacturing device; and a step of manufacturing a stretch film from said waste raw materials using said stretch film manufacturing device, wherein said waste raw materials consist of consumer waste raw materials having non-uniform density and melt index, and said stretch film manufacturing device comprises: an extruder that melts said waste raw materials by heat and pressure and discharges them in the form of a molten film; a storage die that receives and injects the molten film discharged from said extruder; and a cooling device that cools the molten film that has passed through said storage die to form a stretch film. A method for manufacturing a stretch film made from waste raw materials, comprising: an injection tube for moving a molten film extruded from the storage die to the cooling device; wherein the extruder comprises an extrusion tube for mixing and conveying molten raw materials, and the extrusion tube comprises a spiral screw made of an alloy material, and the spiral screw comprises a conveying section, a compression section, and a metering section for the molten film; wherein a first pressure sensor is disposed at the outlet of the storage die and a second pressure sensor is disposed at the outlet of the extrusion tube, and the extrusion amount of the molten film is maintained constant by controlling the rotational speed of the screw in the metering section based on the difference in pressure measured by the first pressure sensor and the second pressure sensor; wherein a filter is disposed between the extrusion tube and the storage die to filter out impurities from the molten film, and wherein the injection tube is formed in the shape of a corrugated tube so that foreign substances within the molten film settle at the lower end of the corrugated tube. Claim 2 delete Claim 3 A method for manufacturing a stretch film made from waste raw materials, characterized in that, in claim 1, the spiral screw is divided into a conveying section for conveying the molten film in the order of the molten film being extruded, a compression section for compressing the molten film, and a metering section for discharging the molten film at a constant density. Claim 4 A method for manufacturing a stretch film made from waste raw materials, characterized in that, in paragraph 3, the screw pitch of the conveying section is wider than the pitch of the compression section and the metering section, and the pitch of the compression section gradually narrows as it moves toward the extrusion direction. Claim 5 A method for manufacturing a stretch film made from waste raw materials, characterized in that, in claim 4, the height of the screw rotating blade is greater in the order of the conveying section, the metering section, and the compression section. Claim 6 A method for manufacturing a stretch film made from waste raw materials, characterized in that, in claim 5, the depth of the screw groove is greater in the order of the conveying section, the compression section, and the metering section. Claim 7 delete Claim 8 A method for manufacturing a stretch film made from waste raw materials, characterized in that, in claim 6, the filter is formed with a first filter section, a spacer, and a second filter section in the order of the direction in which the molten film is extruded, the first filter section is a nonwoven fabric produced by a melt-blown method, the second filter section is made of stainless steel and has a pore size of 150 to 400 mesh, and the spacer is formed of a non-filtered scrim material. Claim 9 delete Claim 10 delete Claim 11 delete Claim 12 delete Claim 13 delete

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