Cross-laminated film composed of single material and method for manufacturing same

Abstract

The present invention relates to a cross-laminated film and a method for manufacturing same in which a cylindrical plastic film manufactured by blown film extrusion is obliquely cut to have a spiral shape, an adhesive layer made of the same material is extrusion-coated onto one sheet of the obliquely cut film, and then another sheet of the obliquely cut film is laminated such that directional grains of the films intersect, thereby forming a film having intersecting directional grains. According to the present invention, it is possible to provide a cross-laminated film having excellent tensile strength, elongation, tear strength, recyclability, and the like.

Description

Cross-laminated film composed of a single material and method for manufacturing the same

[0001] The present invention relates to a cross-laminated film composed of a single material and a method for manufacturing the same. More specifically, the present invention relates to a cross-laminated film and a method for manufacturing the same, wherein a cylindrical plastic film manufactured by a blown film extrusion method is diagonally cut into a spiral shape and then laminated with an adhesive of the same material as the diagonally cut film to form a cross-shaped directional grain.

[0002] The recent revision of the Resource Recycling Act has led to a rapid increase in demand for recyclable packaging materials. To be considered recyclable, packaging materials must receive an "Excellent" recyclability rating, and to achieve this, single-material packaging materials are being developed. As an alternative, cross-laminated plastic films, which possess superior properties by complementing the properties of PE, have been developed. However, conventional cross-laminated plastic films use polyurethane or acrylate adhesives in the cross-lamination process, which classifies them as composite materials rather than single-material ones, limiting their recyclability.

[0003] For example, Korean Patent Application No. 10-2006-0082930 discloses a cross-laminated plastic film having a structure of HDPE / polyurethane / HDPE using polyurethane as an adhesive in a lamination process. However, the disclosed film is classified as a composite material rather than a single material because the content of polyurethane adhesive exceeds 5%, which has resulted in limitations in recyclability.

[0004] Accordingly, the purpose of the present invention is to provide a cross-laminated film composed of a single material and a method for manufacturing the same.

[0005] The present invention provides a cross-laminated film, which is a film in which a cylindrical plastic film manufactured by a blown film extrusion method is cut at an angle of 22.5 to 67.5° to form a spiral shape, an adhesive layer of the same material is extruded onto one sheet of the cut film, and then another sheet of the cut film is laminated so that the directional grains of the films intersect, thereby forming a film with a cross-shaped directional grain.

[0006] In addition, the present invention provides a method for manufacturing a cross-laminated film, comprising the steps of: manufacturing a cylindrical plastic film by a blown film extrusion method; cutting the cylindrical plastic film at an angle of 22.5 to 67.5 degrees to form a spiral shape; extrusion-coating an adhesive layer of the same material on one sheet of the cut film; and laminating another sheet of the cut film so that the directional grains of the films intersect to manufacture a film having a cross-shaped directional grain.

[0007] According to the present invention, a cross-laminated film having excellent tensile strength, elongation, tear strength, etc. can be provided.

[0008] The cross-laminated film according to the present invention is made of a single material and has excellent recyclability by using an adhesive layer of the same material as the film to be laminated without using a polyurethane or acrylate adhesive in the cross-laminated lamination process.

[0009] FIG. 1 is a manufacturing process flow chart of a method for manufacturing a cross-laminated film according to one embodiment of the present invention.

[0010] Figure 2 is a schematic diagram of a manufacturing process of a method for manufacturing a cross-laminated film according to one embodiment of the present invention.

[0011] Figure 3 is a cross-sectional schematic diagram of a cross-laminated film according to one embodiment of the present invention.

[0012] Hereinafter, the present invention will be described in detail.

[0013]

[0014] The cross-laminated film of the present invention is a film in which a cylindrical plastic film manufactured by a blown film extrusion method is cut at an angle of θ to have a spiral shape, an adhesive layer of the same material as the film to be laminated is extruded and coated on one sheet of the cut film, and then another sheet of the cut film is laminated so that the directional grains of the films intersect, thereby forming a film with a cross-shaped directional grain.

[0015] According to one embodiment of the present invention, the plastic film may be selected from the group consisting of high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), and polyethylene terephthalate (PET).

[0016] For example, the cylindrical plastic film may be a high-density polyethylene (HDPE) film.

[0017] According to one embodiment of the present invention, θ may be, but is not limited to, 22.5 to 67.5°.

[0018] In the present invention, the term 'obliquely cut film' refers to a film manufactured by a blown film extrusion method and obliquely cut at an angle of θ to form a spiral shape from a cylindrical plastic film.

[0019] Preferably, the cross shape may be an orthogonal shape.

[0020] For example, the cross-laminated film may be a CCL HDPE film, which is formed by cutting a cylindrical high-density polyethylene (HDPE) film manufactured by a blown film extrusion method at an angle of 22.5 to 67.5 degrees into a spiral shape, extrusion-coating an adhesive layer made of high-density polyethylene (HDPE) material on one sheet of the obliquely cut film, and then laminating another sheet of the obliquely cut film so that the directional grains of the films intersect, thereby forming a film with orthogonal directional grains, i.e., a film in which two sheets of obliquely cut films are laminated so that the directional grains of the films intersect are referred to as a 'CCL film' (Cross Cutting Lamination Film) (spiral cross-laminated film).

[0021] Conventional polyethylene films were either uniaxially oriented polyethylene (MOPE) films or biaxially oriented polyethylene (BOPE) films extruded using the blown process. Therefore, the orientation in the machine direction (MD) was higher than in the transverse direction (TD), resulting in a problem of directional characteristics (split, tearing characteristics).

[0022] To solve these problems, the present invention provides a cross-laminated film (CCL film) having equally excellent tensile strength, elongation, tear strength, etc. in both MD and TD directions.

[0023] The cross-laminated film of the present invention is a film having excellent tensile strength, elongation, tear strength, etc., by cutting a cylindrical plastic film manufactured by a blown film extrusion method at an angle of θ to have a spiral shape, and laminating one sheet of the inclined-cut film on another sheet of the inclined-cut film so that the directional grains of the films intersect, thereby forming a cross-shaped directional grain.

[0024] In addition, the cross-laminated film of the present invention is a film in which an adhesive layer of the same material is extruded and coated on one sheet of an inclined cut film and then another sheet of an inclined cut film is laminated thereon.

[0025] The cross-laminated film of the present invention can be classified as a single material by using an adhesive layer of the same material as the film without using a polyurethane or acrylate adhesive in the cross-laminated lamination process.

[0026] Conventional cross-laminated films have the problem of being difficult to recycle because they are classified as composite materials by forming an adhesive layer with a different material from the film between the laminated films.

[0027] The thickness of the adhesive layer may be 0.5 to 10 μm.

[0028] If the thickness of the adhesive layer is less than 0.5㎛, the adhesiveness may be insufficient, and if it exceeds 10㎛, the recyclability may be poor.

[0029]

[0030] FIG. 3 is a schematic cross-sectional view of a cross-laminated film according to one embodiment of the present invention. The cross-laminated film of the present invention has a structure in which an outer layer (10) and an inner layer (30) made of a film cut at an angle of θ are laminated by an adhesive layer (20) made of the same material as the outer layer (10) and the inner layer (30).

[0031]

[0032] In addition, the method for manufacturing a cross-laminated film of the present invention includes the steps of manufacturing a cylindrical plastic film by a blown film extrusion method; the step of obliquely cutting the cylindrical plastic film at an angle of θ so as to have a spiral shape; the step of extrusion-coating an adhesive layer of the same material on one sheet of the obliquely cut film; and the step of laminating another sheet of obliquely cut film so that the directional grains of the films intersect to manufacture a film having a cross-shaped directional grain.

[0033]

[0034] According to one embodiment of the present invention, the plastic film may be selected from the group consisting of high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), and polyethylene terephthalate (PET).

[0035] For example, the cylindrical plastic film may be a high-density polyethylene (HDPE) film.

[0036] According to one embodiment of the present invention, θ may be, but is not limited to, 22.5 to 67.5°.

[0037] Preferably, the cross shape may be an orthogonal shape.

[0038] Hereinafter, the present invention will be described in more detail through specific examples and comparative examples.

[0039]

[0040] [ingredient]

[0041] For high-density polyethylene (HDPE) products, MI 0.05 g / 10 min, density 0.956 g / cm 3 SK products were used.

[0042] Linear low-density polyethylene (LLDPE) products have an MI of 1 g / 10 min and a density of 0.925 g / cm. 2 LG Chemical products were used.

[0043] Low-density polyethylene (LDPE) products have an MI of 1 g / 10 min and a density of 0.920 g / cm. 2 LG Chemical products were used.

[0044] Polypropylene (PP) products have MI 1g / 10min and density 0.900g / cm 2 LG Chemical products were used.

[0045] Polyethylene terephthalate (PET) products have an MI of 1 g / 10 min and a density of 1.20 g / cm2 LG Chemical products were used.

[0046]

[0047] <Example 1> Manufacturing of CCL HDPE film

[0048] High-density polyethylene (HDPE) (MI 0.05 g / 10 min, density 0.956 g / cm 3 ) 300 kg was fed into the extruder of a blown bubble film forming machine, and a blown film with a thickness of 50 ㎛ was manufactured under the following conditions.

[0049] <Film forming conditions>

[0050] Extrusion cylinder temperature: 170℃, die temperature: 170℃, extrusion amount: 50kg / hour,

[0051] Circular die: 200mm, die gap width: 0.7mm,

[0052] Blow-up ratio: 5.0, take-up speed: 25 m / min.

[0053]

[0054] In cooling the tube bubble, the neck of the bubble was gradually cooled to 80°C by blowing air from the first blower, the expanded portion of the bubble was gradually cooled to 60°C by blowing air from the second blower, the frost line region was gradually cooled to 40°C by blowing air from the third blower, and the bubble region was maintained at 40°C to manufacture a cylindrical plastic film.

[0055] The above cylindrical plastic film was cut at a 45° angle to form a spiral shape. High-density polyethylene (HDPE) was fed into an extrusion coating die, and one sheet of the cut film was extrusion-coated (20 μm thick). Then, another sheet of the cut film was laminated and laminated to obtain a film with a directional grain in an alternating weave pattern. This is referred to as a CCL HDPE film.

[0056]

[0057] <Example 2> Manufacture of CCL LLDPE film

[0058] Linear low-density polyethylene (LLDPE) (MI 1 g / 10 min, density 0.925 g / cm 3 ) 300 kg was fed into the extruder of a blown film forming machine and a film with a thickness of 50 ㎛ was manufactured under the following conditions.

[0059] <Film forming conditions>

[0060] Extrusion cylinder temperature: 170℃, die temperature: 170℃, extrusion amount: 50kg / hour,

[0061] Circular die: 200mm, die gap width: 1.2mm,

[0062] Blow-up ratio: 4.0, take-up speed: 35 m / min.

[0063]

[0064] In cooling the tube bubble, the neck of the bubble was gradually cooled to 80°C by blowing air from the first blower, the expanded portion of the bubble was gradually cooled to 60°C by blowing air from the second blower, the frost line region was gradually cooled to 40°C by blowing air from the third blower, and the bubble region was maintained at 40°C to manufacture a cylindrical plastic film.

[0065] The above cylindrical plastic film was cut at a 45° angle to form a spiral shape. After feeding linear low-density polyethylene (LLDPE) into an extrusion coating die, one sheet of the cut film was extrusion-coated (20 μm thick), and then another sheet of the cut film was laminated and laminated to obtain a film with a directional grain in an alternating weave pattern. This is referred to as a CCL LLDPE film.

[0066]

[0067] <Example 3> Manufacture of CCL LDPE film

[0068] Low-density polyethylene (LDPE) (MI 1g / 10min, density 0.920g / cm 3) 300 kg was fed into the extruder of a blown film forming machine, and a blown film with a thickness of 50 ㎛ was manufactured under the following conditions.

[0069] <Film forming conditions>

[0070] Extrusion cylinder temperature: 150℃, die temperature: 160℃, extrusion amount: 50kg / hour,

[0071] Circular die: 200mm, die gap width: 1.5mm,

[0072] Blow-up ratio: 4.0, take-up speed: 35 m / min.

[0073]

[0074] In cooling the tube bubble, the neck of the bubble was gradually cooled to 80°C by blowing air from the first blower, the expanded portion of the bubble was gradually cooled to 60°C by blowing air from the second blower, the frost line region was gradually cooled to 40°C by blowing air from the third blower, and the bubble region was maintained at 40°C to manufacture a cylindrical plastic film.

[0075] The above cylindrical plastic film was cut at a 45° angle to form a spiral shape. After feeding low-density polyethylene (LDPE) into an extrusion coating die, one sheet of the cut film was extrusion-coated (20 μm thick), and then another sheet of the cut film was laminated and laminated to obtain a film with a directional grain in an alternating weave pattern. This is referred to as a CCL LDPE film.

[0076]

[0077] <Example 4> Manufacture of CCL PP film

[0078] Polypropylene (PP) (MI 1g / 10min, density 0.900g / cm 3 ) 300 kg was fed into the extruder of a blown bubble film forming machine, and a blown film with a thickness of 50 ㎛ was manufactured under the following conditions.

[0079] <Film forming conditions>

[0080] Extrusion cylinder temperature: 170℃, die temperature: 180℃, extrusion amount: 50kg / hour,

[0081] Circular die: 200mm, die gap width: 1.0mm,

[0082] Blow-up ratio: 4.0, take-up speed: 25 m / min.

[0083]

[0084] In cooling the tube bubble, the neck of the bubble was gradually cooled to 80°C by blowing air from the first blower, the expanded portion of the bubble was gradually cooled to 60°C by blowing air from the second blower, the frost line region was gradually cooled to 40°C by blowing air from the third blower, and the bubble region was maintained at 40°C to manufacture a cylindrical plastic film.

[0085] The above cylindrical plastic film was cut at a 45° angle to form a spiral shape. Polypropylene (PP) was fed into an extrusion coating die, and one sheet of the cut film was extrusion-coated (20 μm thick). Then, another sheet of the cut film was laminated and laminated to obtain a film with a directional grain in an alternating weave pattern. This film is referred to as a CCL PP film.

[0086]

[0087] <Example 5> Manufacturing of CCL PET film

[0088] Polyethylene terephthalate (PET) (MI 1g / 10min, density 1.20g / cm 3 ) 300 kg was fed into the extruder of a blown film forming machine, and a blown film with a thickness of 50 ㎛ was manufactured under the following conditions.

[0089] <Film forming conditions>

[0090] Extrusion cylinder temperature: 205℃, die temperature: 255℃, extrusion amount: 30kg / hour,

[0091] Circular die: 200mm, die gap width: 1.0mm,

[0092] Blow-up ratio: 3.5, take-up speed: 18 m / min.

[0093]

[0094] In cooling the tube bubble, the neck of the bubble was gradually cooled to 80°C by blowing air from the first blower, the expanded portion of the bubble was gradually cooled to 60°C by blowing air from the second blower, the frost line region was gradually cooled to 40°C by blowing air from the third blower, and the bubble region was maintained at 40°C to manufacture a cylindrical plastic film.

[0095] The above cylindrical plastic film was cut at a 45° angle to form a spiral shape. Polyethylene terephthalate (PET) was fed into an extrusion coating die, and one sheet of the cut film was extrusion-coated (20 μm thick). Then, another sheet of the cut film was laminated and laminated to obtain a film with a directional grain in an alternating weave pattern. This is referred to as a CCL PET film.

[0096] The materials and thicknesses of each layer of Examples 1 to 5 are summarized in Table 1 below.

[0097]

[0098] <Comparative Examples 1 to 5>

[0099] As a comparative example, a single-layer film was prepared as described in Table 1 below.

[0100] <Comparative Example 6>

[0101] A CCL HDPE film was manufactured in the same manner as in Example 1, except that a polyacrylate adhesive was hot melt-bonded instead of extrusion-coating the HDPE adhesive layer.

[0102] Comparative Example 7

[0103] A CCL LLDPE film was manufactured in the same manner as in Example 2, except that a polyacrylate adhesive was hot melt-bonded instead of extrusion-coating the LLDPE adhesive layer.

[0104] Comparative Example 8

[0105] A CCL LDPE film was manufactured in the same manner as in Example 3, except that a polyacrylate adhesive was hot melt-bonded instead of extrusion-coating the LDPE adhesive layer.

[0106] <Comparative Example 9>

[0107] A CCL PP film was manufactured in the same manner as in Example 4, except that a polyacrylate adhesive was hot melt-bonded instead of extrusion-coating the PP adhesive layer.

[0108] Comparative Example 10

[0109] A CCL PET film was manufactured in the same manner as in Example 5, except that a polyacrylate adhesive was hot melt-bonded instead of extrusion-coating the PET adhesive layer.

[0110]

[0111] CCL film layer-by-layer material and structure Structure 1st layer - inner layer 2nd layer - adhesive layer 3rd layer - outer layer Total thickness unit ㎛ ㎛ ㎛ Comparative example 1 HDPE (120) -- 120 Comparative example 2 LLDPE (120) -- 120 Comparative example 3 LDPE (120) -- 120 Comparative example 4 PP (120) -- 120 Comparative example 5 PET (120) -- 120 Comparative example 6 HDPE (50) Polyacrylate (10) HDPE (50) 110 Comparative example 7 LLDPE (50) Polyacrylate (10) LLDPE (50) 110 Comparative example 8 LDPE (50) Polyacrylate (10) LDPE (50) 110 Comparative example 9PP(50)Polyacrylate(10)PP(50)110Comparative Example 10PET(50)Polyacrylate(10)PET(50)110Example 1HDPE(50)HDPE(20)HDPE(50)120Example 2LLDPE(50)LLDPE(20)LLDPE(50)120Example 3LDPE(50)LDPE(20)LDPE(50)120Example 4PP(50)PP(20)PP(50)120Example 5PET(50)PET(20)PET(50)120

[0112]

[0113] <Experimental Example 1> Mechanical properties

[0114] The mechanical properties of the specimens manufactured in the examples and comparative examples were evaluated in both MD and TD directions.

[0115] Tensile strength and elongation: Tensile strength (kgf / ㎠) and elongation (%) were measured for the specimens using the ASTM D638 method, and the results are shown in Table 2 below.

[0116] <Experimental Example 2> Recyclability

[0117] Recyclability was evaluated for the specimens manufactured in the examples and comparative examples.

[0118] PEAK error range analysis: FT-IR, DSC, and TGA component analyses were performed on the specimens to analyze the PEAK error range, and the results are shown in Table 2 below.

[0119]

[0120] Mechanical properties Recyclability Structure Tensile strength (MD / TD) Elongation (MD / TD) FT-IR, DSC, TGA Material evaluation (within 10% error range) Unit kg f / cm 2 %PEAK Error Range Analysis Single / Composite Comparison Example 1264 / 236 298 / 5223% Single Comparison Example 2207 / 184 381 / 6155% Single Comparison Example 3237 / 154 517 / >800 6% Single Comparison Example 4311 / 269 135 / 4564% Single Comparison Example 5354 / 30 280 / 1286% Single Comparison Example 6378 / 365>800 / >800 33% Composite Comparison Example 7327 / 323>800 / >800 41% Composite Comparison Example 8280 / 282>80 0 / >800 28% Composite Comparative Example 9 381 / 360 >800 / >800 26% Composite Comparative Example 10 475 / 424 >800 / >800 44% Composite Example 1 388 / 376 >800 / >800 6% Single Example 2 328 / 332 >800 / >800 5% Single Example 3 281 / 293 >800 / >800 5% Single Example 4 378 / 366 >800 / >800 7% Single Example 5 473 / 463 >800 / >800 8% Single

[0121]

[0122] As a result, as shown in Table 2 above, it can be seen that the tensile strength and elongation of Examples 1 to 5 are significantly increased compared to Comparative Examples 1 to 5, which are single-layer films.

[0123] In addition, it can be seen that examples 1 to 5, which use an adhesive of the same material as the film to be laminated, maintain mechanical properties at the same level as compared to comparative examples 6 to 10, which use a polyacrylate adhesive of a different material from the film to be laminated.

[0124] In addition, in the case of Examples 1 to 5 using an adhesive of the same material as the laminated film, the PEAK error range in the component analysis (FT-IR, DSC, TGA) was within 10%, so it was classified as a single material, indicating 'excellent' recyclability, whereas in the case of Comparative Examples 6 to 10 using a polyacrylate adhesive of a different material from the laminated film, the PEAK error range in the component analysis (FT-IR, DSC, TGA) exceeded 10%, so it was classified as a composite material, indicating 'difficult' recyclability.

[0125] [Explanation of symbols]

[0126] 10: outer layer, 20: adhesive layer, 30: inner layer

[0127] <Research and Development Project Information>

[0128] - Assignment ID: 1425179703

[0129] - Assignment number: RS-2023-00267724

[0130] - Ministry name: Ministry of SMEs and Startups

[0131] - Project Management (Professional) Agency Name: Small and Medium Business Technology Information Promotion Agency

[0132] - Research Project Name: Small and Medium Enterprise Technology Innovation Development Project (Export-Oriented)

[0133] - Research Project Name: Development of a high-barrier film with guaranteed durability and excellent biodegradability in water and soil.

[0134] - Project execution organization name: R&F Chemical Co., Ltd. [Host]

[0135] Research period: July 17, 2023 - July 16, 2027 (4 years and 0 months)

Claims

1. A cross-laminated film is a film in which a cylindrical plastic film manufactured by a blown film extrusion method is obliquely cut at an angle of θ to form a spiral shape, an adhesive layer of the same material is extruded and coated on one sheet of the obliquely cut film, and then another sheet of obliquely cut film is laminated so that the directional grains of the films intersect, thereby forming a film with a cross-shaped directional grain.

2. In paragraph 1, The above plastic film is a cross-laminated film selected from the group consisting of high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP) and polyethylene terephthalate (PET).

3. In paragraph 1, A cross-laminated film wherein the above θ is 22.5 to 67.5°.

4. In paragraph 1, A cross-laminated film wherein the above cross shape is an orthogonal shape.

5. A step of manufacturing a cylindrical plastic film using a blown film extrusion method; A step of cutting the cylindrical plastic film at an angle of θ to form a spiral shape; A step of extrusion coating an adhesive layer of the same material on one sheet of the above-mentioned inclined cut film; and A method for manufacturing a cross-laminated film, comprising the step of laminating another sheet of inclined cut film so that the directional grains of the films intersect, thereby manufacturing a film having a cross-shaped directional grain formed therein.

6. In paragraph 1, A method for producing a cross-laminated film, wherein the above plastic film is selected from the group consisting of high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), and polyethylene terephthalate (PET).

7. In paragraph 1, A method for manufacturing a cross-laminated film, wherein the above θ is 22.5 to 67.5°.

8. In paragraph 1, A method for manufacturing a cross-laminated film, wherein the above cross shape is an orthogonal shape.

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