Composition for biaxially oriented film, and biaxially oriented film and method for preparing same

Abstract

Disclosed is a composition for a biaxially oriented film, the composition comprising: a petroleum resin; and a high-density polyethylene (HDPE) having a melt index (ASTM D1238, 190°C, 2.16 kg load) of 0.2-1.5 g / 10 min. According to the present invention, due to the petroleum resin, high-temperature stretchability is improved, biaxial stretching can be achieved even in a low-temperature region, optical properties are excellent, processability, roll adhesion, and surface gloss are improved, and mechanical strength and repeated extrusion stability are excellent.

Description

Composition for biaxially stretched film, biaxially stretched film and method for manufacturing the same

[0001] The present invention relates to a composition for a biaxially stretched film, a biaxially stretched film, and a method for manufacturing the same. More specifically, the present invention relates to a composition for a biaxially stretched film, a biaxially stretched film, and a method for manufacturing the same, wherein high-temperature stretchability is improved due to the petroleum resin, biaxial stretching is possible even in low-temperature regions, and not only are optical properties excellent, but processability, roll adhesion, and surface gloss are also improved, and mechanical strength and repetitive extrusion stability are excellent.

[0002]

[0003] Biaxially Oriented Polyethylene (BOPE) is manufactured by stretching conventional polyethylene (PE) film in two axial directions (machine direction and transverse direction) simultaneously or sequentially. Biaxially Oriented Polyethylene has excellent tensile strength, impact strength, and heat resistance, so it can be used in food packaging, industrial packaging materials, labels, and other applications.

[0004] When conventional PE films are biaxially stretched, low-density polymers are used to secure optical properties; however, this presents problems such as difficulty in processing and uneven film formation, making it difficult to apply as a product. Furthermore, existing packaging materials are not manufactured from a single material—such as by using PET, Nylon, or PA substrate layers within a polyethylene inner layer—and thus present issues of being uneco-friendly and non-recyclable.

[0005] To address this, a composition for a biaxially stretched film, a biaxially stretched film, and a method for manufacturing the same are required, which can simultaneously secure not only economic feasibility through reduced process costs by using a single catalyst but also excellent mechanical properties and recyclability of high-density polymers.

[0006] Related prior art is Korean Patent Publication No. 10-2010-0040898.

[0007]

[0008] The objective of the present invention is to provide a composition for a biaxially stretched film, a biaxially stretched film, and a method for manufacturing the same, wherein the yield point is reduced due to the petroleum resin and the elongation up to the strain hardening point in the tensile curve is extended to improve high-temperature elongation, and biaxial stretching is possible even in a low-temperature region by extending the processing temperature.

[0009] Another objective of the present invention is to provide a composition for a biaxially stretched film, a biaxially stretched film, and a method for manufacturing the same, which enables the production of a film with excellent optical properties such as transparency and reduced external haze during biaxial stretching by making it possible to manufacture a sheet with a smooth surface due to the petroleum resin.

[0010] Another objective of the present invention is to provide a composition for a biaxially stretched film, a biaxially stretched film, and a method for manufacturing the same, which can produce a film with improved processability, roll adhesion, and surface gloss due to the petroleum resin.

[0011] Another objective of the present invention is to provide a composition for a biaxially stretched film, a biaxially stretched film, and a method for manufacturing the same, which can produce a film with excellent tensile strength and impact strength due to increased crystallinity caused by petroleum resin.

[0012] Another objective of the present invention is to provide a composition for a biaxially stretched film, a biaxially stretched film, and a method for manufacturing the same, which can maintain the physical properties of the polymer resin even during repeated extrusion and has excellent recycling characteristics due to high film reprocessability.

[0013] The above and other objectives of the present invention can all be achieved by the present invention described below.

[0014]

[0015] 1. One aspect of the present invention relates to a composition for a biaxially stretched film comprising a petroleum resin; and high-density polyethylene (HDPE) having a melt index (ASTM D1238, 190°C, 2.16 kg load) of 0.2 to 1.5 g / 10 min.

[0016] 2. In the above 1 embodiment, the high-density polyethylene (HDPE) may have a maximum elongation (ASTM D638, 120°C to 135°C, 300% / s) of 3000 to 9000% and an elongation (ASTM D638, 120°C to 135°C, 300% / s) at the point of strain hardening in the tensile curve of 1500 to 5000%.

[0017] 3. In the above 1 to 2 embodiments, the high-density polyethylene (HDPE) has a density of 0.935 to 0.960 g / cc and can be prepared by vapor phase polymerization with a single Cr catalyst.

[0018] 4. In the above 1 to 3 embodiments, the petroleum resin may be included in an amount of 2 to 20 weight% of 100 weight% of the composition for the biaxially stretched film.

[0019] 5. In the above 1 to 4 embodiments, the petroleum resin may have a weight-average molecular weight (Mw) of 300 to 1,200 g / mol.

[0020] 6. In the above 1 to 5 embodiments, the composition for the biaxially stretched film may have a melt index (ASTM D1238, 190°C, 2.16 kg load) of 0.2 to 2.0 g / 10 min.

[0021] 7. Another aspect of the present invention relates to a biaxially stretched film formed from the composition for a biaxially stretched film of the 1 to 6 embodiments above.

[0022] 8. In the above 7 embodiments, the biaxially stretched film may have a haze (ASTM D1003) of 8% or less.

[0023] 9. Another aspect of the present invention is a biaxially stretched film comprising petroleum resin and high-density polyethylene, wherein the biaxially stretched film has a haze (ASTM D1003) of 8% or less.

[0024] 10. In the above 9 embodiments, the biaxially stretched film may have a transparency (ASTM D1003) of 95% or more.

[0025] 11. In the above 9 to 10 embodiments, the biaxially stretched film may have a light transmittance (ASTM D1003) of 92% or more.

[0026] 12. In the above 9 to 11 embodiments, the biaxially stretched film may have a glossiness (ASTM D523, roll temperature of 40°C to 80°C, 45°) of 52 or higher.

[0027] 13. In the above 9 to 12 embodiments, the biaxially stretched film may have an impact strength (ASTM D3420, 6.4 kg weight) of 600 kgf·cm or more.

[0028] 14. In the above 9 to 13 embodiments, the biaxial stretching processing temperature of the biaxially stretched film may be 115℃ to 135℃.

[0029] 15. Another aspect of the present invention relates to a method for manufacturing a biaxially stretched film. The manufacturing method comprises the steps of: extruding a composition for a biaxially stretched film of the 1 to 6 embodiments to produce a sheet; and biaxially stretching the sheet.

[0030] 16. In the above 15 embodiments, the biaxial stretching may be performed by longitudinal stretching 3 to 7 times in the longitudinal direction (MD) and transverse stretching 4 to 9 times in the transverse direction (TD) at 115°C to 135°C.

[0031] 17. Another aspect of the present invention relates to a packaging material. The packaging material comprises the biaxially stretched film of the 9 to 14 embodiments.

[0032] 18. In the above 17 embodiments, the packaging material may be recyclable by including only polyethylene material.

[0033] 19. In the above 17 to 18 embodiments, the packaging material may comprise a polyethylene substrate; and a biaxially stretched film laminated on the polyethylene substrate.

[0034]

[0035] The present invention has the effect of providing a composition for a biaxially stretched film, a biaxially stretched film, and a method for manufacturing the same, wherein high-temperature elongation is improved due to the petroleum resin, biaxial stretching is possible even in low-temperature regions, optical properties are excellent, processability, roll adhesion, and surface gloss are improved, tensile strength and impact strength are excellent, and recyclability is possible due to excellent repeated extrusion stability.

[0036]

[0037] The present invention will be described in more detail below. Where terms such as 'comprising,' 'having,' and 'consisting of' are used in this specification, other parts may be added unless 'only' is used. Where a component is expressed in the singular, it includes cases where it includes the plural unless specifically stated otherwise.

[0038] In interpreting the components, they are interpreted to include a margin of error even in the absence of a separate explicit statement.

[0039] The present invention relates to a composition for a biaxially stretched film, a biaxially stretched film, and a method for manufacturing the same.

[0040] One aspect of the present invention relates to a composition for a biaxially stretched film. The composition for a biaxially stretched film comprises (A) a petroleum resin; and (B) high-density polyethylene (HDPE).

[0041]

[0042] (A) Petroleum balance

[0043] When the above petroleum resin is mixed with high-density polyethylene (HDPE), the surface characteristics of the biaxially stretched film are improved, and transparency and light transmittance are enhanced, resulting in excellent optical properties. Furthermore, when the above petroleum resin is added, the tensile strength, impact strength, and thermal shrinkage rate of the biaxially stretched film are improved, leading to excellent mechanical properties and enhanced processability and performance as a packaging material. Additionally, when the above petroleum resin is added, the yield point is reduced and the elongation up to the strain hardening point on the tensile curve is extended, thereby improving high-temperature elongation and enabling biaxial stretching even in low-temperature regions due to the expansion of the processing temperature range. Moreover, when the above petroleum resin is added, roll adhesion and surface gloss are improved, thereby enhancing processing stability from the sheet manufacturing stage to the biaxial stretching process.

[0044] The above petroleum resin is a hydrogenated hydrocarbon resin, C 5　 Suzy, C 9　 Suzy, C5 / C 9　 It may include a mixed resin, dicyclopentadiene (DCPD), or a mixture thereof. However, it is not limited to the petroleum resin described above. In particular, the petroleum resin may be an environmentally friendly hydrogenated petroleum resin that undergoes a hydrogenation process to remove unsaturated functional groups. For example, the above C 5　 The resin can contribute to increasing the transparency and processability of the biaxially oriented film, and C 9　 The resin can improve the tensile strength and durability of biaxially oriented films.

[0045] The above petroleum resin may have a weight-average molecular weight (Mw) of 300 to 1,200 g / mol. In a specific example, the weight-average molecular weight (Mw) may be 350 to 900 g / mol, for example, 400 to 800 g / mol. Within this range, the softening point is low, and above the softening point, it may have low viscosity like a liquid. When manufacturing a biaxially stretched film, the high-temperature stretchability, processability, roll adhesion, etc., are excellent, and the mechanical strength, optical properties, and heat shrinkage of the film may be excellent.

[0046] The above petroleum resin may have a melt viscosity (ASTM D3236, 180°C) of 100 to 2,000 cPs. In a specific example, the melt viscosity may be 200 to 1,400 cPs, for example, 250 to 800 cPs. Within this range, when manufacturing a biaxially stretched film, high-temperature stretchability, processability, roll adhesion, etc. are excellent, and the mechanical strength, optical properties, and heat shrinkage of the film may be excellent.

[0047] The above petroleum resin may have a softening point (ASTM E 28) of 90 to 140°C. In a specific example, the softening point may be 100 to 135°C, for example, 103 to 132°C. When manufacturing a biaxially stretched film within this range, the high-temperature stretchability, processability, roll adhesion, etc., are excellent, and the mechanical strength, optical properties, and heat shrinkage of the film may be excellent.

[0048] The above petroleum resin may be included in an amount of 2 to 20 weight% of 100 weight% of the composition for the biaxially stretched film. In a specific example, it may be included in an amount of 3 to 12 weight%, for example, 4.5 to 5.5 weight%. Within the above range, when manufacturing a biaxially stretched film, excellent high-temperature stretchability, processability, roll adhesion, as well as mechanical strength, optical properties, and heat shrinkage may be achieved.

[0049]

[0050] (B) High-density polyethylene (HDPE)

[0051] The above high-density polyethylene (HDPE) has a melt index (ASTM D1238, 190°C, 2.16 kg load) of 0.2 to 1.5 g / 10 min. In a specific example, the melt index may be 0.25 to 1.2 g / 10 min, for example, 0.5 to 0.8 g / 10 min. Within this range, the tensile strength and impact strength of the biaxially stretched film are excellent, and the high-temperature elongation, processability, and repeated extrusion stability may be excellent during biaxial stretching processing.

[0052] The above high-density polyethylene (HDPE) may have a maximum elongation (ASTM D638, 120°C to 135°C, 300% / s) of 3000 to 9000%. In a specific example, the maximum elongation may be 4000 to 8000%, for example, 5000 to 7000%. Within this range, the tensile strength and impact strength of the biaxially stretched film are excellent, and the high-temperature elongation, processability, and repeated extrusion stability may be excellent during biaxial stretching processing.

[0053] The above high-density polyethylene (HDPE) may have an elongation (ASTM D638, 120°C to 135°C, 300% / s) from the point of strain hardening in the tensile curve to 1500 to 5000%. In a specific example, the elongation may be 2000 to 4000%, for example, 2500 to 3500%. Within this range, the tensile strength and impact strength of the biaxially stretched film are excellent, and the high-temperature elongation, processability, and repeated extrusion stability may be excellent during biaxial stretching processing.

[0054] The above high-density polyethylene (HDPE) may have a density of 0.935 to 0.960 g / cc. In a specific example, the density may be 0.940 to 0.955 g / cc, for example, 0.943 to 0.947 g / cc. Within this range, the tensile strength and impact strength of the biaxially stretched film are excellent, and the high-temperature elongation, processability, and repeated extrusion stability may be excellent during biaxial stretching processing.

[0055] The above high-density polyethylene (HDPE) can be manufactured by vapor phase polymerization using a single Cr catalyst. When a single catalyst is used, the manufacturing process is simpler and process costs are reduced compared to when heterogeneous metal catalysts are used, resulting in superior economic efficiency, and the reaction can proceed stably even under changes in conditions. In particular, since Cr single-catalyst-based high-density polyethylene has a broad molecular weight distribution, it is possible to manufacture high-density biaxially stretched films with higher mechanical strength and processability than when using metallocene or Ziegler-Natta catalysts.

[0056] The above high-density polyethylene (HDPE) may be included in an amount of 80 to 98 weight% of 100 weight% of the composition for the biaxially stretched film. In a specific example, it may be included in an amount of 88 to 97 weight%, for example, 94.5 to 95.5 weight%. Within the above range, the tensile strength and impact strength of the biaxially stretched film are excellent, and the high-temperature stretchability, processability, and repeated extrusion stability during biaxial stretching processing may be excellent.

[0057] The above composition for biaxially stretched films may include various additives, such as antioxidants, neutralizing agents, and extrusion molding agents, within a range that does not impair the effects of the present invention.

[0058] When manufacturing the above composition for biaxially stretched films, if high-density polyethylene is used alone, the surface shape is unstable during extrusion processing, and rapid crystal formation occurs when the molten resin comes into contact with a cooling roll. Consequently, roll adhesion is poor, and there is a problem of being relatively rough despite the surface smoothness being 100 degrees. Therefore, the present invention can manufacture a sheet with a smooth surface with a GM of 70 or higher by adding a low molecular weight material such as petroleum resin to delay rapid crystal formation at the contact area with the roll. In addition, a film having excellent optical properties can be manufactured during biaxial stretching processing.

[0059] The above composition for the biaxially stretched film may have a melt index (ASTM D1238, 190°C, 2.16 kg load) of 0.2 to 2.0 g / 10 min. In a specific example, the melt index may be 0.4 to 1.5 g / 10 min, for example, 0.5 to 1.2 g / 10 min. Within this range, the tensile strength and impact strength of the biaxially stretched film are excellent, and the high-temperature stretchability, processability, and repeated extrusion stability may be excellent during biaxial stretching processing.

[0060]

[0061] Another aspect of the present invention relates to a biaxially stretched film formed from the above-described composition for a biaxially stretched film.

[0062] The above biaxially stretched film may have a haze (ASTM D1003, 125°C) of 8% or less. In a specific example, the haze may be 3% to 7%, for example, 4% to 6.5%. That is, a sheet with a smooth surface can be manufactured by adding petroleum resin, and external haze can be reduced because the surface is flat during biaxial stretching. Within the above range, the optical properties of the film are excellent, making it suitable for use as a packaging material.

[0063]

[0064] Another aspect of the present invention is a biaxially stretched film comprising petroleum resin and high-density polyethylene, wherein the biaxially stretched film has a haze (ASTM D1003) of 8% or less. In a specific embodiment, the haze may be 3% to 7%, for example, 4% to 6.5%. That is, by adding petroleum resin, a sheet with a smooth surface can be manufactured, and the surface is flat during biaxial stretching, thereby reducing external haze. Within this range, the optical properties of the film are excellent, making it suitable for use as a packaging material.

[0065] The above biaxially stretched film may have a transparency (ASTM D1003) of 95% or more. In a specific example, the transparency may be 96% to 99.8%, for example, 96.8% to 99%. Within this range, the optical properties of the film are excellent, making it suitable for use as a packaging material where transparency is required.

[0066] The above biaxially stretched film may have a light transmittance (ASTM D1003) of 92% or more. In a specific example, the light transmittance may be 92.8% to 96%, for example, 93.3% to 95%. Within this range, the optical properties of the film are excellent, making it suitable for use as a packaging material where light transmittance is required.

[0067] The above biaxially stretched film has a gloss (ASTM D523, roll temperature of 40℃ to 80℃, 45 o ) may be 52 or higher. In a specific example, the glossiness may be 55 to 95, for example, 60 to 91. Within this range, the surface smoothness is high, so the roll adhesion is excellent and the thickness of the film can be uniform.

[0068] The above biaxially stretched film may have an impact strength (ASTM D3420, 6.4 kg weight) of 600 kgf·cm or more. In a specific example, the impact strength may be 700 kgf·cm to 1200 kgf·cm, for example, 800 kgf·cm to 1150 kgf·cm, preferably 850 kgf·cm to 1100 kgf·cm. That is, the degree of crystallization may be increased by adding petroleum resin. The mechanical properties of the film may be excellent within the above range.

[0069] The processing temperature of the above biaxially stretched film may be 115°C to 135°C. In a specific example, the processing temperature may be 120°C to 130°C, for example, 123°C to 125°C. That is, by expanding the processing temperature range in the biaxial stretching process, stretching can be performed in a relatively low temperature range and processing stability can be improved.

[0070]

[0071] Another aspect of the present invention relates to a method for manufacturing a biaxially stretched film. The manufacturing method comprises the steps of: extruding a composition for a biaxially stretched film described above to produce a sheet; and biaxially stretching the sheet.

[0072] The above method can produce a biaxially stretched film with excellent processability, mechanical properties, and optical properties by melt-extruding a composition for a biaxially stretched film containing high-density polyethylene with added petroleum resin to produce a sheet, and then biaxially stretching the sheet.

[0073] The temperature during the extrusion above may be 180°C to 280°C, for example, 200°C to 270°C, and preferably 230°C to 260°C. The extrusion may be performed using a twin-screw extruder or a single-screw extruder. Within the above range, the tensile strength and impact strength of the biaxially stretched film are excellent, and the high-temperature elongation, processability, and repeated extrusion stability may be excellent during biaxial stretching processing.

[0074] The above biaxial stretching can be performed by longitudinally stretching 3 to 7 times in the longitudinal direction (MD) and transversely stretching 4 to 9 times in the transverse direction (TD) at 115°C to 135°C.

[0075] In a specific example, the temperature may be 123°C to 129°C, for example, 125°C to 128°C. Within this range, the thickness of the film may be uniform, and uneven stretching and breakage may not occur.

[0076] In addition, in a specific example, the stretching range may be 4.2 to 7.6 times in the longitudinal direction, for example, 5.4 to 7.2 times, and 5 to 10 times in the transverse direction, for example, 7.2 to 9.4 times. In the above range, no breakage occurs, and tensile strength and impact strength may be excellent. That is, in the above range, the thickness variation of the film is small, and processability can be improved, so high-quality packaging materials can be manufactured.

[0077] The above method may further include a step of heat-setting and cooling after the step of biaxially stretching the sheet. The temperature during heat-setting may be 120°C to 140°C in a specific example, for example, 125°C to 135°C, preferably 127°C to 130°C. Within this range, the tensile strength, impact strength, and post-processability (printability, heat shrinkage, coating ability) of the biaxially stretched film may be excellent.

[0078] The biaxially stretched film produced by the above method may have a thickness of 15 to 50 μm, 15 to 40 μm in specific examples, and, for example, 15 to 30 μm.

[0079]

[0080] Another aspect of the present invention relates to a packaging material. The packaging material comprises the biaxially stretched film described above.

[0081] The above packaging material may be recyclable by including only a single material of polyethylene. If the substrate layer of the existing packaging material is replaced with a biaxially stretched film and manufactured from a single material that is recyclable by more than 90%, it can be eco-friendly. In addition, it may have excellent repeated extrusion stability (maintenance of polymer properties, gel stability, reprocessability, etc.).

[0082] The above packaging material may comprise a polyethylene substrate; and a biaxially stretched film laminated on the polyethylene substrate. The packaging material in which the biaxially stretched film is laminated on the polyethylene substrate can be used in various fields, and preferably can be utilized as a disposable packaging material, a pharmaceutical packaging material, a food packaging material, etc. The above packaging material can provide a high-quality packaging material by including a biaxially stretched film that has excellent stretchability, processability, transparency, as well as impact strength.

[0083]

[0084] Hereinafter, the structure and operation of the present invention will be explained in more detail through preferred embodiments of the present invention. However, the following embodiments are intended to aid in understanding the present invention, and the scope of the present invention is not limited to the following embodiments.

[0085]

[0086] Examples

[0087] The product specifications used in the following examples and comparative examples are as follows:

[0088] (a1) Petroleum resin: A product with a weight-average molecular weight of 1,200 g / mol, a melt viscosity (ASTM D3236, 180℃) of 1,000 cPs, and a softening point (ASTM E 28) of 130℃ was used.

[0089] (a2) Petroleum resin: A product with a weight-average molecular weight of 540 g / mol, a melting viscosity (ASTM D3236, 800 cPs at 180°C), and a softening point (ASTM E 28) of 120°C was used.

[0090] (b1) High-density polyethylene: used, which has a density (ASTM D1505) of 0.945 g / cc and a melt index (ASTM D1238, 190℃, 2.16 kg load) of 0.7 g / 10 min and was polymerized in the vapor phase based on a Cr catalyst.

[0091] The maximum elongation (ASTM D638, 120°C to 135°C, 300% / s) is 6350% at 120°C and 7000% at 125°C or more, and the elongation until strain hardening (ASTM D638, 120°C to 135°C, 300% / s) is 2160% at 120°C and 3200% at 125°C.

[0092] (b2) High-density polyethylene: used, which has a density (ASTM D1505) of 0.96 g / cc and a melt index (ASTM D1238, 190℃, 2.16 kg load) of 1.4 g / 10 min and is polymerized in the vapor phase based on a Cr catalyst.

[0093] The maximum elongation (ASTM D638, 120°C to 135°C, 300% / s) is 6500% at 120°C and 7000% at 125°C or more, and the elongation until strain hardening (ASTM D638, 120°C to 135°C, 300% / s) is 2530% at 120°C and 2640% at 125°C.

[0094] (b3) High-density polyethylene: used, which has a density (ASTM D1505) of 0.96 g / cc and a melt index (ASTM D1238, 190℃, 2.16 kg load) of 6.5 g / 10 min and is polymerized based on a ZN catalyst.

[0095] The maximum elongation (ASTM D638, 120°C to 135°C, 300% / s) is 550% at 120°C and 1200% at 125°C, and the elongation until strain hardening (ASTM D638, 120°C to 135°C, 300% / s) is 550% at 120°C and 1200% at 125°C.

[0096] (b4) High-density polyethylene: used, which has a density (ASTM D1505) of 0.945 g / cc and a melt index (ASTM D1238, 190℃, 2.16 kg load) of 1.4 g / 10 min and is polymerized based on a ZN catalyst.

[0097] The maximum elongation (ASTM D638, 120°C to 135°C, 300% / s) is 6500% at 120°C and 7000% at 125°C or more, and the elongation until strain hardening (ASTM D638, 120°C to 135°C, 300% / s) is 2500% at 120°C and 4300% at 125°C.

[0098] (c) Linear low-density polyethylene: used with a density (ASTM D1505) of 0.916 g / cc and a melt index (ASTM D1238, 190℃, 2.16 kg load) of 3.5 g / 10 min.

[0099] (d) Low-density polyethylene: used with a density (ASTM D1505) of 0.921 g / cc and a melt index (ASTM D1238, 190℃, 2.16 kg load) of 3.0 g / 10 min.

[0100]

[0101] Example 1

[0102] A mixed resin was prepared by combining 5% by weight of petroleum resin (a1) and 95% by weight of high-density polyethylene (b1).

[0103] After melt-extruding the above mixed resin through a T-die extruder, a sheet with a thickness of 1 mm was produced by attaching it to a cooling roll at 70°C under air-knife pressure. Subsequently, a 9 cm x 9 cm specimen was prepared, and a biaxially stretched film was produced by sequentially stretching MD and TD at a 5*9 (MD*TD) magnification and a stretching speed of 100% / s using a biaxial stretching LAB evaluation device (Bruckner KARO 5.0) at 120°C to 130°C (e.g., 120°C, 123°C, 125°C, 127°C, 130°C).

[0104]

[0105] Example 2

[0106] The above example was performed in the same manner as Example 1, except that it was formulated with 5% by weight of petroleum resin (a1), 90% by weight of high-density polyethylene (b1), and 5% by weight of high-density polyethylene (b3).

[0107]

[0108] Example 3

[0109] The above example was performed in the same manner as Example 1, except that it was formulated with 7.5 wt% petroleum resin (a1) and 92.5 wt% high-density polyethylene (b1).

[0110]

[0111] Example 4

[0112] The procedure was carried out in the same manner as Example 1 above, except that it was formulated with 5% by weight of petroleum resin (a2) and 95% by weight of high-density polyethylene (b1).

[0113]

[0114] Example 5

[0115] The above example was performed in the same manner as Example 1, except that it was formulated with 5% by weight of petroleum resin (a2) and 95% by weight of high-density polyethylene (b2).

[0116]

[0117] Comparative Example 1

[0118] The above example was performed in the same manner as Example 1, except that petroleum resin (a1) was not added and 100% by weight of high-density polyethylene (b1) was used.

[0119]

[0120] Comparative Example 2

[0121] The above example was performed in the same manner as Example 1, except that petroleum resin (a1) was not added and 100% by weight of high-density polyethylene (b4) was used.

[0122]

[0123] Comparative Example 3

[0124] The procedure was carried out in the same manner as Example 1 above, except that it was formulated with 90% by weight of high-density polyethylene (b1) and 10% by weight of high-density polyethylene (b3).

[0125]

[0126] Comparative Example 4

[0127] The procedure was carried out in the same manner as Example 1 above, except that the mixture was formulated with 90% by weight of high-density polyethylene (b1) and 10% by weight of linear low-density polyethylene (c).

[0128]

[0129] Comparative Example 5

[0130] The procedure was carried out in the same manner as Example 1 above, except that the mixture was composed of 90% by weight of high-density polyethylene (b1) and 10% by weight of low-density polyethylene (d).

[0131]

[0132] The physical properties of the manufactured sheets and biaxially stretched films were evaluated using the following methods, and the results are shown in Tables 1 and 2:

[0133]

[0134] Methods for evaluating physical properties

[0135] (1) Melt Index (g / 10min)

[0136] Using a TOYOSEIKI MELT INDEXER P-101 measuring device, measurements were taken at 190°C with a piston load of 2.16 kg in accordance with ASTM D1238.

[0137]

[0138] (2) Glossiness

[0139] The surface gloss of the sheet was measured at a 45° angle using a BYK-GADNER MIRROR-TRI-GLOSS measuring device in accordance with ASTM D523.

[0140] The above sheet was prepared to a thickness of 300 μm by attaching molten resin extruded from a T-die at 250°C to a cooling roll. At this time, the sheet sample was prepared by varying the temperature of the cooling roll from 40°C to 100°C.

[0141]

[0142] (3) Maximum elongation (%)

[0143] Tensile strength was measured using a high-temperature elongation UTM machine (Instron 8800) in accordance with ASTM D638. The elongation at the point of fracture in the measured tensile strength data was defined as the maximum elongation and calculated.

[0144] For measurement, a tensile specimen made in the shape of a dog bone using a 1 mm thick sheet was used. After fixing the specimen to the UTM equipment, the set temperature (120℃, 125℃, 131℃) was maintained for more than 5 minutes, and the measurement was performed at a stretching speed of 300% / s.

[0145]

[0146] (4) Elongation (%) from the strain hardening point in the tensile curve

[0147] The change in specimen length at the strain hardening point, which is the point where the curve begins to rise after the yield point in the tensile curve, was measured, and the value calculated as a percentage was expressed as elongation.

[0148]

[0149] (5) Film thickness (㎛)

[0150] The film was sampled into a rectangular shape measuring 1 m in the measurement direction and 40 mm in the width direction, and the thickness of the film was measured using a micrometer.

[0151]

[0152] (6) Transmittance, Haze, and Clarity (%)

[0153] Using a haze meter (Haze Gardner, Gardner BYK) and in accordance with ASTM D1003, the total light transmittance, haze, and transparency of the center of the biaxially stretched film were measured at a temperature of 25°C, and the average of the values ​​measured 5 times with the position of the center of the film changed was calculated.

[0154]

[0155] (7) Impact strength (kgf·cm)

[0156] Impact strength was measured using an IMPACT TESTER (Spencer Impact Tester, Thwing-Albert) in accordance with ASTM D3420, with the weight of the reference weight set to 6.4 kg, at a temperature of 25°C.

[0157]

[0158] (8) Thermal shrinkage rate (%)

[0159] A heat-controlled constant temperature bath was used, and samples were taken in accordance with ASTM D1204 with a width of 100 mm in the MD direction and 100 mm in the TD direction. Subsequently, the film was placed between flat mesh nets and treated in an oven controlled to a temperature of 100°C for 5 minutes. Afterward, the length (L) of the shrunk film was measured, and the thermal shrinkage rate was calculated.

[0160] Thermal shrinkage rate (%) = ( L0 - L / L0)Y100

[0161] (L0 above is the length of the film before heat treatment, and L is the length of the film after heat treatment)

[0162]

[0163] (9) Repeat extrusion stability (reworkability) (%)

[0164] Repetitive extrusion stability was evaluated based on the change in Melt Index (MI) measured with a 2.16 kg weight at 190°C in accordance with ASTM D1238 using a Melt Flow indexer (Gotterfert MI-3). Repetitive extrusion stability was calculated by comparing the MI of the resin with the initial MI of the resin after three repetitive extrusions in a 30 mm twin-screw extruder and determining the absolute change.

[0165] Repeat extrusion stability = (|MI0-MI Re | / MI0) X 100

[0166] (The above MI0 is the MI of the initial resin, and MI Re is the MI of the resin after 3 repeated extrusions)

[0167] [Table 1]

[0168]

[0169]

[0170] From the results of Table 1 above, it can be confirmed that Examples 1 to 5 have improved processability, roll adhesion, and surface gloss, and excellent high-temperature elongation compared to Comparative Examples 1 to 5. In particular, it can be confirmed that Comparative Examples 1 to 2 have relatively higher roll temperatures compared to Examples 1 to 5, which indicates that roll adhesion is possible only when the temperature is increased.

[0171] [Table 2]

[0172]

[0173] From the results of Table 2 above, it can be confirmed that Examples 1 to 5 are capable of biaxial stretching even in a low-temperature range compared to Comparative Examples 1 to 5, and have excellent optical properties, impact strength, thermal shrinkage, and repeated extrusion stability.

[0174]

[0175] Simple variations or modifications of the present invention can be easily implemented by those skilled in the art, and all such variations or modifications are considered to be included within the scope of the present invention.

Claims

Petroleum balance; and A composition for a biaxially stretched film comprising high-density polyethylene (HDPE) having a melt index (ASTM D1238, 190°C, 2.16 kg load) of 0.2 to 1.5 g / 10 min. In paragraph 1, A composition for a biaxially stretched film, wherein the above high-density polyethylene (HDPE) has a maximum elongation (ASTM D638, 120°C to 135°C, 300% / s) of 3000 to 9000% and an elongation (ASTM D638, 120°C to 135°C, 300% / s) at the point of strain hardening in the tensile curve of 1500 to 5000%. In paragraph 1, The above high-density polyethylene (HDPE) has a density of 0.935 to 0.960 g / cc and is a composition for a biaxially stretched film prepared by vapor phase polymerization with a single Cr catalyst. In paragraph 1, A biaxially stretched film composition in which the above petroleum resin is included in an amount of 2 to 20 weight% of 100 weight% of the above biaxially stretched film composition. In paragraph 1, The above petroleum resin is a composition for a biaxially stretched film having a weight-average molecular weight (Mw) of 300 to 1,200 g / mol. In paragraph 1, The above composition for a biaxially stretched film is a composition for a biaxially stretched film having a melt index (ASTM D1238, 190°C, 2.16 kg load) of 0.2 to 2.0 g / 10 min. A biaxially stretched film formed from a composition for a biaxially stretched film according to any one of claims 1 to 6. In Paragraph 7, The above biaxially stretched film is a biaxially stretched film having a haze (ASTM D1003) of 8% or less. It is a biaxially oriented film comprising petroleum resin and high-density polyethylene, and The above biaxially stretched film is a biaxially stretched film having a haze (ASTM D1003) of 8% or less. In Paragraph 9, The above biaxially stretched film is a biaxially stretched film having a transparency (ASTM D1003) of 95% or more. In Paragraph 9, The above biaxially stretched film is a biaxially stretched film having a light transmittance (ASTM D1003) of 92% or higher. In Paragraph 9, The above biaxially stretched film is a biaxially stretched film having a glossiness (ASTM D523, roll temperature of 40° to 80°, 45°) of 52 or higher. In Paragraph 9, The above biaxially stretched film is a biaxially stretched film having an impact strength (ASTM D3420, 6.4 kg weight) of 600 kgf·cm or more. In Paragraph 9, A biaxially stretched film having a processing temperature of 115℃ to 135℃. A sheet is manufactured by extruding a composition for a biaxially stretched film according to any one of claims 1 to 6; and Biaxially stretching the above sheet; A method for manufacturing a biaxially stretched film comprising the steps. In paragraph 15, A method for manufacturing a biaxially stretched film, wherein the above biaxial stretching is performed by performing longitudinal stretching 3 to 7 times in the longitudinal direction (MD) and transverse stretching 4 to 9 times in the transverse direction (TD) at 115°C to 135°C. A packaging material comprising a biaxially oriented film according to any one of paragraphs 9 through 14. In Clause 17, the above packaging material is a recyclable packaging material comprising only a single material of polyethylene. In Clause 17, the above packaging material is Polyethylene substrate; and The biaxially stretched film laminated on the polyethylene substrate; Packaging material including

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