Polyolefin film for easy die-cutting and easy peel-off sticker packaging and method for manufacturing the same

Abstract

The present application belongs to the technical field of polyolefin film, and relates to a polyolefin film for easy die-cutting and easy peeling adhesive packaging and a preparation method thereof. The present application discloses a polyolefin film for easy die-cutting and easy peeling adhesive packaging, which comprises an outer functional layer, a first bonding layer, a middle barrier layer, a second bonding layer and an inner functional layer. The outer functional layer comprises a surface high-temperature-resistant layer, a middle functional layer and a first easy die-cutting functional layer, wherein the first easy die-cutting functional layer is connected with the first bonding layer. The inner functional layer comprises a second easy die-cutting functional layer, a middle functional layer and an easy peeling heat-sealing layer, wherein the second easy die-cutting functional layer is connected with the second bonding layer. The middle functional layer comprises one or more of an anti-UV functional layer and an anti-puncture functional layer. The present application further discloses a preparation method of the polyolefin film for easy die-cutting and easy peeling adhesive packaging.

Description

Technical Field

[0001] This invention belongs to the field of polyolefin film technology, and relates to a polyolefin film for easy die-cutting and easy peeling for skin packaging and its preparation method. Background Technology

[0002] Skin packaging refers to the process of vacuum-sealing the contents between a transparent food skin packaging film and a tray under vacuum conditions. This skin packaging method effectively preserves the color, aroma, and freshness of the product, offering the dual benefits of good three-dimensional display and vacuum preservation. Skin packaging can be widely used for fresh produce as well as cooked meat products.

[0003] Currently, the skin packaging film market is mainly divided into imported and domestic films. Imported skin films have higher costs and longer ordering cycles. On the other hand, some domestic skin film products have unstable quality, insufficient abrasion and puncture resistance, inconsistent peel strength with the base film, poor die-cutting, and are prone to fraying, affecting the appearance of the product and failing to meet the needs of end consumers. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in the prior art by proposing a multi-layered, UV-resistant, oxidation-resistant, heat-resistant, easily die-cut and peelable polyolefin film for skin packaging.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A polyolefin film for easy die-cutting and easy peeling skin packaging, the polyolefin film for easy die-cutting and easy peeling skin packaging includes an outer functional layer, a first adhesive layer, an intermediate barrier layer, a second adhesive layer, and an inner functional layer.

[0007] The outer functional layer includes a surface high-temperature resistant layer, an intermediate functional layer, and a first easy-to-die-cut functional layer, wherein the first easy-to-die-cut functional layer is in contact with the first adhesive layer;

[0008] The inner functional layer includes a second easy-to-die-cut functional layer, an intermediate functional layer, and an easy-to-peel heat-sealable layer, wherein the second easy-to-die-cut functional layer is connected to the second adhesive layer;

[0009] The intermediate functional layer includes one or more of the following: UV-resistant functional layer and puncture-resistant functional layer.

[0010] Preferably, the easy-to-die-cut and easy-to-peel polyolefin film for skin packaging comprises, from the outside to the inside: a high-temperature resistant surface layer, a UV-resistant functional layer, a first easy-to-die-cut functional layer, a first adhesive layer, an intermediate barrier layer, a second adhesive layer, a second easy-to-die-cut functional layer, a puncture-resistant functional layer, and an easy-to-peel heat-sealable layer.

[0011] Preferably, the thickness ratio of the outer functional layer to the inner functional layer is (1-2):1.

[0012] Further preferably, the thickness ratio of the outer functional layer to the inner functional layer is (1.1~1.5):1.

[0013] Preferably, the raw materials for the surface high-temperature resistant layer, by weight, include: 50-70 parts high-density polyethylene resin, 30-50 parts low-density polyethylene resin, 0.5-2 parts open slip masterbatch, and 0.5-2 parts processing aids.

[0014] Preferably, the raw materials for the UV-resistant functional layer, by weight, include: 10-25 parts UV-resistant resin, 30-50 parts low-density polyethylene resin, 30-50 parts ethylene-vinyl acetate copolymer resin, and 0.1-1 parts processing aids.

[0015] Preferably, the raw material of the intermediate barrier layer, by weight, includes 100 parts of ethylene-vinyl alcohol copolymer resin.

[0016] Preferably, the raw materials for the puncture-resistant functional layer, by weight, include: 15-35 parts of low-density polyethylene resin, 55-70 parts of ethylene-vinyl acetate copolymer resin, 5-10 parts of maleic anhydride-modified low-density polyethylene resin, and 0.5-2 parts of processing aids.

[0017] Preferably, the raw materials for the easily peelable heat-sealable layer, by weight, include: 40-99 parts of polyethylene elastomer resin, 0-60 parts of ethylene-vinyl acetate copolymer resin, 0-60 parts of polypropylene resin, 1-3 parts of open slip masterbatch, and 0.5-2 parts of processing aids.

[0018] Preferably, the raw materials for the first and second easy-to-die-cut functional layers, by weight, include: 10 to 35 parts of ionic polymer resin, 55 to 75 parts of low-density polyethylene, 5 to 10 parts of maleic anhydride-modified low-density polyethylene resin, and 0.5 to 2 parts of processing aids.

[0019] Further preferred, the mass ratio of ionic polymer resin, low-density polyethylene, and maleic anhydride-modified low-density polyethylene resin in the first easy-to-die-cut functional layer and the second easy-to-die-cut raw material is (2.5-4):(6-9):1.

[0020] Further preferred, the first easy-to-die-cut functional layer and the second easy-to-die-cut functional layer are different.

[0021] Preferably, the raw materials for the first adhesive layer and the second adhesive layer, by weight, include: 70-95 parts of maleic anhydride-modified low-density polyethylene resin and 5-30 parts of low-density polyethylene resin.

[0022] Further preferably, the first adhesive layer and the second adhesive layer are identical.

[0023] This invention also discloses a method for preparing an easy-to-die-cut and easy-to-peel skin packaging polyolefin film. The preparation method includes: adding the pre-treated easy-to-peel heat-sealable layer raw material and the raw materials of the other layers into the corresponding barrels of an extruder, heating the extruder in sections, pressing and plasticizing through a filter screen, and then mixing evenly through the blown film head channel, heating and heat preservation, blowing, adjusting, cooling, slitting and winding.

[0024] Preferably, the pretreatment process of the easily peelable heat-sealing layer includes: feeding the raw material particles into a high-speed mixer in proportion and mixing them evenly, then passing them through a plastic internal mixer for high-temperature mixing, a conical twin-screw feeding device for shearing and compression, a single-screw extruder for extrusion, and cooling and granulation.

[0025] Further preferably, the mixing temperature of the plastic internal mixer is 100℃; the conical twin-screw feeding device is heated in stages, wherein the first stage heating temperature is 125℃, the second stage heating temperature is 158℃, the third stage heating temperature is 190℃, and the fourth stage heating temperature is 210℃; the single-screw extruder is heated in stages, wherein the first stage heating temperature is 195℃, the second stage heating temperature is 195℃, the third stage heating temperature is 175℃, and the fourth stage heating temperature is 160℃; and the cooling method is natural air cooling.

[0026] Preferably, the raw materials for the high-temperature resistant surface layer, UV-resistant functional layer, first easy-to-die-cut functional layer, second easy-to-die-cut functional layer, and easy-to-peel heat-sealable layer are set at the following temperatures during the segmented heating process in the extruder: the first segment heating temperature is 60°C, the second segment heating temperature is 175°C, and the third to seventh segments heating temperatures are 210°C.

[0027] Preferably, the raw materials for the first and second adhesive layers are heated in the extruder in stages at the following temperatures: 50°C for the first stage, 165°C for the second stage, and 225°C for the third to seventh stages.

[0028] Preferably, the raw material of the intermediate barrier layer is set to the following temperatures during the segmented heating of the extruder: 50°C for the first segment, 175°C for the second segment, and 215°C for the third to seventh segments.

[0029] Preferably, the temperatures of each zone of the blown film die head are as follows: 200°C for the first zone, 215°C for the second to ninth zones, and 195°C for the tenth zone.

[0030] Preferably, the cooling temperature is 30–40°C.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The easy-to-die-cut and easy-to-peel polyolefin film for skin packaging of the present invention includes an outer functional layer, a first adhesive layer, an intermediate barrier layer, a second adhesive layer, and an inner functional layer, wherein the outer functional layer and the inner functional layer have multiple special functions, enabling the polyolefin film for skin packaging to meet various application environments.

[0033] 2. The raw material of the easy-to-peel heat-sealable layer of the inner functional layer of the present invention needs to be pre-treated. The twin-screw granulation process can ensure that the components of the heat-sealable layer are mixed more evenly. Compared with adding it directly to the extruder of the blown film machine, the more even mixing will make the peeling effect of the finished product uniform and stable.

[0034] 3. The thickness of the outer functional layer of the polyolefin film for easy die-cutting and easy peeling of the present invention is greater than or equal to the thickness of the inner functional layer, which helps to reduce costs. Furthermore, the outer functional layer of a certain thickness can ensure sufficient puncture resistance while reducing costs. Detailed Implementation

[0035] The following are specific embodiments of the present invention, which further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0036] The raw materials used in this invention include:

[0037] High-density polyethylene resin: HDPE, manufactured by ExxonMobil, grade 4009MC, melt index 0.9 g / 10 min, density 0.940 g / cm³ 3 ;

[0038] Low-density polyethylene (LDPE), produced by Yangzi-BASF, grade 2420H, melt index 2.0 g / 10 min, density 0.923 g / cm³ 3 ;

[0039] UV-resistant resin: Produced by Huayi-Weiba Company, grade PE UVS-28, melt index 20g / 10min, density 0.94g / cm³ 3 ;

[0040] Ethylene-vinyl acetate copolymer resin: EVA, manufactured by Hanwha Total, grade E180L, melt index 2.0 g / 10 min, density 0.94 g / cm³ 3 ;

[0041] Ion-polymer resin: Surlyn, manufactured by DuPont, grade 1601-2, melt index 2.0 g / 10 min, density 0.94 g / cm³ 3 ;

[0042] Maleic anhydride modified low-density polyethylene resin: manufactured by DuPont, grade 41E687, melt index 1.7 g / 10 min, density 0.91 g / cm³ 3 ;

[0043] Ethylene-vinyl alcohol copolymer resin: manufactured by Nippon Seizo Co., Ltd., grade AT4403B, melt index 3.5 g / 10 min, density 1.14 g / cm³ 3 ;

[0044] Ethylene-vinyl alcohol copolymer resin: manufactured by Nippon Seizo Co., Ltd., grade ET3803RB, melt index 4.0 g / 10 min, density 1.17 g / cm³. 3 ;

[0045] Polypropylene resin: Produced by Borouge, grade RB707CF, melt index 1.5 g / 10 min, density 0.9 g / cm³ 3 ;

[0046] Polyethylene elastomer resin: manufactured by SABIC, grade S100L, melt index 1.0 g / 10 min, density 0.903 g / cm³ 3 ;

[0047] Processing aid masterbatch: manufactured by Shulman Company, grade AMF705HF;

[0048] Open-ended slip masterbatch: manufactured by Shulman, grade FSU105E.

[0049] Example 1

[0050] The easy-to-die-cut and easy-to-peel skin packaging polyolefin film of this embodiment includes, from the outside to the inside: a 20μm high-temperature resistant surface layer, a 12μm UV-resistant functional layer, a 12μm first easy-to-die-cut functional layer, a 7μm first adhesive layer, a 7μm intermediate barrier layer, a 7μm second adhesive layer, a 10μm second easy-to-die-cut functional layer, a 10μm puncture-resistant functional layer, and a 15μm easy-to-peel heat-sealable layer.

[0051] Weigh the raw materials according to the following proportions:

[0052] The raw materials for the surface high-temperature resistant layer include: 60 parts high-density polyethylene resin (4009MC), 38 parts low-density polyethylene resin (2420H), 1 part open slip masterbatch (FSU105E), and 1 part processing aid (AMF705HF).

[0053] The raw materials for the UV-resistant functional layer include: 15 parts UV-resistant resin (PE UVS-28), 45 parts low-density polyethylene resin (2420H), 39.5 parts ethylene-vinyl acetate copolymer resin (E180L), and 0.5 parts processing aid (AMF705HF).

[0054] The raw materials for the first easy-to-die-cut functional layer include: 30 parts of ionomer resin (1601-2), 61 parts of low-density polyethylene (2420H), 8 parts of maleic anhydride modified low-density polyethylene resin (41E687), and 1 part of processing aid (AMF705HF).

[0055] The raw materials for the first adhesive layer include: 75 parts of maleic anhydride modified low-density polyethylene resin (41E687) and 25 parts of low-density polyethylene resin (2420H).

[0056] The raw materials for the intermediate barrier layer include: 100 parts of ethylene-vinyl alcohol copolymer resin (AT4403B);

[0057] The raw materials for the second adhesive layer include: 75 parts of maleic anhydride modified low-density polyethylene resin (41E687) and 25 parts of low-density polyethylene resin (2420H).

[0058] The raw materials for the second easy-to-die-cut functional layer include: 25 parts of ionomer resin (1601-2), 66 parts of low-density polyethylene (2420H), 8 parts of maleic anhydride modified low-density polyethylene resin (41E687), and 1 part of processing aid (AMF705HF).

[0059] The raw materials for the puncture-resistant functional layer include: 32 parts of low-density polyethylene resin (2420H), 60 parts of ethylene-vinyl acetate copolymer resin (E180L), 7 parts of maleic anhydride modified low-density polyethylene resin (41E687), and 1 part of processing aid (AMF705HF).

[0060] The raw materials for the easy-peel heat-sealable layer include: 97 parts polyethylene elastomer resin (S00L), 2 parts open slip masterbatch (FSU105E), and 1 part processing aid (AMF705HF).

[0061] The raw material for the easy-to-peel heat-seal layer is fed into a high-speed mixer and mixed for 30 minutes until homogeneous. It is then sequentially passed through a plastic internal mixer at 100°C for high-temperature internal mixing; a conical twin-screw feeder is used for shearing and compression, with segmented heating temperatures of 125°C, 158°C, 190°C, and 210°C for the first, second, third, and fourth stages; a single-screw extruder is used for extrusion, with segmented heating temperatures of 195°C, 175°C, and 160°C for the fourth stage; and finally, the pre-treated easy-to-peel heat-seal layer raw material particles are cooled and granulated by natural air.

[0062] The raw materials for the high-temperature resistant surface layer, UV-resistant functional layer, first easy-to-die-cut functional layer, second easy-to-die-cut functional layer, and easy-to-peel heat-sealable layer are heated in stages in the extruder at the following temperatures: first stage heating temperature 60℃, second stage heating temperature 175℃, and third to seventh stage heating temperatures 210℃; the raw materials for the first adhesive layer and second adhesive layer are heated in stages in the extruder at the following temperatures: first stage heating temperature 50℃, second stage heating temperature 165℃, and third to seventh stage heating temperatures 225℃; the raw materials for the intermediate barrier layer are heated in stages in the extruder at the following temperatures: first stage heating temperature 50℃, second stage heating temperature 175℃, and third to seventh stage heating temperatures 215℃.

[0063] After being heated by an extruder, the particles are pressurized and plasticized through a filter screen (mesh size 40 / 100 / 300 / 80 / 40). Then, they are mixed evenly and heated and kept warm in the blown film head channel. The temperatures of each zone of the die head are as follows: Zone 1 heating temperature 200℃, Zones 2 to 9 heating temperature 215℃, Zone 10 heating temperature 225℃. The particles are initially blown into a plastic tubular film shape. By adjusting the internal and external cooling air volume and traction speed, the initially blown tubular film is blown to the required thickness and width. It is then cooled by rotary traction (40℃), edge trimming, and stepped cooling (40℃, 35℃, 30℃) by an annealing device, and finally slit online. Finally, it is wound into a roll film by a winding device.

[0064] The performance of the prepared easy-to-die-cut and easy-to-peel polyolefin film for skin packaging was tested, and the results are shown in Table 1.

[0065] Example 2

[0066] The difference compared to Example 1 is that

[0067] Weigh the raw materials according to the following proportions: The raw materials for the surface high-temperature resistant layer include: 55 parts high-density polyethylene resin (4009MC), 43 parts low-density polyethylene resin (2420H), 1 part open slip masterbatch (FSU105E), and 1 part processing aid (AMF705HF).

[0068] The raw materials of the UV-resistant functional layer include: 18 parts UV-resistant resin (PE UVS-28), 46 parts low-density polyethylene resin (2420H), 35 parts ethylene-vinyl acetate copolymer resin (E180L), and 1 part processing aid (AMF705HF).

[0069] The raw materials for the first easy-to-die-cut functional layer include: 30 parts of ionomer resin (1601-2), 61 parts of low-density polyethylene (2420H), 8 parts of maleic anhydride modified low-density polyethylene resin (41E687), and 1 part of processing aid (AMF705HF).

[0070] The raw materials for the first adhesive layer include: 75 parts of maleic anhydride modified low-density polyethylene resin (41E687) and 25 parts of low-density polyethylene resin (2420H).

[0071] The raw materials for the intermediate barrier layer include: 100 parts of ethylene-vinyl alcohol copolymer resin (AT4403B);

[0072] The raw materials for the second adhesive layer include: 75 parts of maleic anhydride modified low-density polyethylene resin (41E687) and 25 parts of low-density polyethylene resin (2420H).

[0073] The raw materials for the second easy-to-die-cut functional layer include: 25 parts of ionomer resin (1601-2), 66 parts of low-density polyethylene (2420H), 8 parts of maleic anhydride modified low-density polyethylene resin (41E687), and 1 part of processing aid (AMF705HF).

[0074] The raw materials for the puncture-resistant functional layer include: 27 parts of low-density polyethylene resin (2420H), 62 parts of ethylene-vinyl acetate copolymer resin (E180L), 10 parts of maleic anhydride modified low-density polyethylene resin (41E687), and 1 part of processing aid (AMF705HF).

[0075] The raw materials for the easy-peel heat-sealable layer include: 95 parts polyethylene elastomer resin (S00L), 3 parts open slip masterbatch (FSU105E), and 2 parts processing aid (AMF705HF).

[0076] The performance of the prepared easy-to-die-cut and easy-to-peel polyolefin film for skin packaging was tested, and the results are shown in Table 1.

[0077] Example 3

[0078] The difference compared to Example 1 is that

[0079] The easy-to-die-cut and easy-to-peel patch packaging polyolefin film of this embodiment includes, from the outside to the inside: a surface high-temperature resistant layer of 21 μm, a UV-resistant functional layer of 15 μm, a first easy-to-die-cut functional layer of 15 μm, a first adhesive layer of 7 μm, an intermediate barrier layer of 7 μm, a second adhesive layer of 7 μm, a second easy-to-die-cut functional layer of 8 μm, a puncture-resistant functional layer of 8 μm, and an easy-to-peel heat-sealable layer of 12 μm.

[0080] The performance of the prepared easy-to-die-cut and easy-to-peel polyolefin film for skin packaging was tested, and the results are shown in Table 1.

[0081] Example 4

[0082] The difference compared to Example 1 is that

[0083] The easy-to-die-cut and easy-to-peel skin packaging polyolefin film of this embodiment includes, from the outside to the inside: a 25μm high-temperature resistant surface layer, a 15μm UV-resistant functional layer, a 15μm first easy-to-die-cut functional layer, a 7μm first adhesive layer, a 7μm intermediate barrier layer, a 7μm second adhesive layer, a 7μm second easy-to-die-cut functional layer, a 7μm puncture-resistant functional layer, and a 10μm easy-to-peel heat-sealable layer.

[0084] The performance of the prepared easy-to-die-cut and easy-to-peel polyolefin film for skin packaging was tested, and the results are shown in Table 1.

[0085] Example 5

[0086] The difference compared to Example 1 is that

[0087] The raw materials for the first easy-to-die-cut functional layer include: 37 parts of ionomer resin (1601-2), 54 parts of low-density polyethylene (2420H), 8 parts of maleic anhydride modified low-density polyethylene resin (41E687), and 1 part of processing aid (AMF705HF).

[0088] The raw materials for the second easy-to-die-cut functional layer include: 35 parts of ionomer resin (1601-2), 56 parts of low-density polyethylene (2420H), 8 parts of maleic anhydride modified low-density polyethylene resin (41E687), and 1 part of processing aid (AMF705HF).

[0089] The performance of the prepared easy-to-die-cut and easy-to-peel polyolefin film for skin packaging was tested, and the results are shown in Table 1.

[0090] Example 6

[0091] The difference compared to Example 1 is that

[0092] The raw materials for the first easy-to-die-cut functional layer include: 51 parts of ionomer resin (1601-2), 40 parts of low-density polyethylene (2420H), 8 parts of maleic anhydride modified low-density polyethylene resin (41E687), and 1 part of processing aid (AMF705HF).

[0093] The raw materials for the second easy-to-die-cut functional layer include: 45 parts of ionomer resin (1601-2), 46 parts of low-density polyethylene (2420H), 8 parts of maleic anhydride modified low-density polyethylene resin (41E687), and 1 part of processing aid (AMF705HF).

[0094] The performance of the prepared easy-to-die-cut and easy-to-peel polyolefin film for skin packaging was tested, and the results are shown in Table 1.

[0095] Example 7

[0096] The difference compared to Example 1 is that

[0097] The raw materials for the first adhesive layer include: 45 parts of maleic anhydride modified low-density polyethylene resin (41E687) and 55 parts of low-density polyethylene resin (2420H).

[0098] The raw materials for the second adhesive layer include: 75 parts of maleic anhydride modified low-density polyethylene resin (41E687) and 25 parts of low-density polyethylene resin (2420H).

[0099] The performance of the prepared easy-to-die-cut and easy-to-peel polyolefin film for skin packaging was tested, and the results are shown in Table 1.

[0100] Example 8

[0101] Compared with Example 1, the difference is that the raw material of the easily peelable heat-sealing layer is not pretreated, but is directly added to the corresponding barrel of the extruder along with the raw materials of the other layers.

[0102] The performance of the prepared polyolefin film for skin packaging was tested, and the results are shown in Table 1.

[0103] Example 9

[0104] The difference compared to Example 1 is that

[0105] The raw materials for the intermediate barrier layer include: 100 parts of ethylene-vinyl alcohol copolymer resin (ET3803RB);

[0106] The raw materials for the easy-peel heat-sealable layer include: 57 parts polyethylene elastomer resin (S00L), 40 parts ethylene-vinyl acetate copolymer resin (E180L), 2 parts open slip masterbatch (FSU105E), and 1 part processing aid (AMF705HF).

[0107] The performance of the prepared polyolefin film for skin packaging was tested, and the results are shown in Table 1.

[0108] Example 10

[0109] The difference compared to Example 1 is that

[0110] The raw materials for the intermediate barrier layer include: 100 parts of ethylene-vinyl alcohol copolymer resin (ET3803RB);

[0111] The raw materials for the easy-peel heat-sealable layer include: 40 parts polyethylene elastomer resin (S00L), 57 parts polypropylene resin (RB707CF), 2 parts open slip masterbatch (FSU105E), and 1 part processing aid (AMF705HF).

[0112] The performance of the prepared polyolefin film for skin packaging was tested, and the results are shown in Table 1.

[0113] Comparative Example 1

[0114] The easy-to-die-cut and easy-to-peel skin packaging polyolefin film of this comparative example has no easy-to-die-cut functional layer, and from the outside to the inside, it includes: a surface high-temperature resistant layer of 26μm, an anti-UV functional layer of 18μm, a first adhesive layer of 7μm, an intermediate barrier layer of 7μm, a second adhesive layer of 7μm, a puncture-resistant functional layer of 15μm, and an easy-to-peel heat-sealing layer of 20μm.

[0115] The performance of the prepared polyolefin film for skin packaging was tested, and the results are shown in Table 1.

[0116] Table 1. Performance Data of Polyolefin Films for Easy-to-Die-Cut and Easy-to-Peel Skin Packaging

[0117]

[0118] Note: Peel strength refers to the peel strength after heat sealing with PP (polypropylene) sheet; UV blocking green indicates UV resistance, the higher the UV blocking rate, the better the UV resistance; elongation at break indicates puncture resistance, the higher the elongation at break, the better the puncture resistance.

[0119] As shown in the table above, the polyolefin film for easy die-cutting and easy peeling of the present invention has good mechanical properties and heat resistance.

[0120] In Examples 3 and 4, the outer functional layer was too thick, which affected die-cutting; in Example 5, the ionic polymer resin content was slightly high, which affected peel strength; in Example 6, the excessive proportion of ionic polymers led to interlayer delamination; in Example 7, the two adhesive layers were different, and the content of maleic anhydride-modified low-density polyethylene resin was low, which led to interlayer delamination; in Example 8, the raw material of the easily peelable heat-sealing layer was not pretreated, which reduced the uniformity of the raw material and led to unstable performance.

[0121] In summary, the easy-to-die-cut and easy-to-peel polyolefin film for skin packaging of the present invention includes an outer functional layer, a first adhesive layer, an intermediate barrier layer, a second adhesive layer, and an inner functional layer, wherein the outer functional layer and the inner functional layer have multiple special functions, enabling the polyolefin film for skin packaging to meet various application environments.

[0122] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A polyolefin film for easy die-cutting and easy-peeling skin packaging, characterized in that, The easy-to-die-cut and easy-to-peel polyolefin film for skin packaging includes an outer functional layer, a first adhesive layer, an intermediate barrier layer, a second adhesive layer, and an inner functional layer. The thickness ratio of the outer functional layer to the inner functional layer is (1.1~1.5):1; The first adhesive layer and the second adhesive layer are the same; The outer functional layer includes a surface high-temperature resistant layer, an intermediate functional layer, and a first easy-to-die-cut functional layer, wherein the first easy-to-die-cut functional layer is in contact with the first adhesive layer; The inner functional layer includes a second easy-to-die-cut functional layer, an intermediate functional layer, and an easy-to-peel heat-sealable layer, wherein the second easy-to-die-cut functional layer is connected to the second adhesive layer; The intermediate functional layer includes one or more of the following: a UV-resistant functional layer and a puncture-resistant functional layer. The raw materials for the first and second easy-to-die-cut functional layers, by weight, include: 10 to 35 parts of ionic polymer resin, 55 to 75 parts of low-density polyethylene, 5 to 10 parts of maleic anhydride-modified low-density polyethylene resin, and 0.5 to 2 parts of processing aids. The mass ratio of ionic polymer resin, low-density polyethylene, and maleic anhydride-modified low-density polyethylene resin in the raw materials of the first and second easy-to-die-cut functional layers is (2.5-4):(6-9):

1.

2. The polyolefin film for easy die-cutting and easy-peeling skin packaging according to claim 1, characterized in that, The easy-to-die-cut and easy-to-peel skin packaging polyolefin film comprises, from the outside to the inside: a 20μm high-temperature resistant surface layer, a 12μm UV-resistant functional layer, a 12μm first easy-to-die-cut functional layer, a 7μm first adhesive layer, a 7μm intermediate barrier layer, a 7μm second adhesive layer, a 10μm second easy-to-die-cut functional layer, a 10μm puncture-resistant functional layer, and a 15μm easy-to-peel heat-sealable layer; The raw materials for the surface high-temperature resistant layer include: 60 parts high-density polyethylene resin, 38 parts low-density polyethylene resin, 1 part open slip masterbatch, and 1 part processing aid. The raw materials for the UV-resistant functional layer include: 15 parts UV-resistant resin, 45 parts low-density polyethylene resin, 39.5 parts ethylene-vinyl acetate copolymer resin, and 0.5 parts processing aids. The raw materials of the first easy-to-die-cut functional layer include: 30 parts of ionomer resin, 61 parts of low-density polyethylene, 8 parts of maleic anhydride-modified low-density polyethylene resin, and 1 part of processing aid. The raw materials for the first adhesive layer include: 75 parts of maleic anhydride-modified low-density polyethylene resin and 25 parts of low-density polyethylene resin. The raw material for the intermediate barrier layer includes: 100 parts of ethylene-vinyl alcohol copolymer resin; The raw materials for the second adhesive layer include: 75 parts of maleic anhydride-modified low-density polyethylene resin and 25 parts of low-density polyethylene resin. The raw materials for the second easy-to-die-cut functional layer include: 25 parts of ionomer resin, 66 parts of low-density polyethylene, 8 parts of maleic anhydride-modified low-density polyethylene resin, and 1 part of processing aid. The raw materials of the puncture-resistant functional layer include: 32 parts of low-density polyethylene resin, 60 parts of ethylene-vinyl acetate copolymer resin, 7 parts of maleic anhydride modified low-density polyethylene resin, and 1 part of processing aid. The raw materials for the easily peelable heat-sealable layer include: 97 parts polyethylene elastomer resin, 2 parts open slip masterbatch, and 1 part processing aid.

3. A method for preparing a polyolefin film for easy die-cutting and easy-peeling skin packaging as described in claim 1, characterized in that, The preparation method includes: adding the pretreated easy-to-peel heat-sealable layer raw material and the raw materials of the other layers into the corresponding barrels of the extruder, heating the extruder in sections, pressing and plasticizing through a filter screen, and then mixing evenly through the blown film die head channel, heating and heat preservation, blowing, adjusting, cooling, slitting and winding.

4. The method for preparing the easily die-cut and easily peelable polyolefin film for patch packaging according to claim 3, characterized in that, The pretreatment process of the easily peelable heat-sealing layer includes: feeding the raw material particles into a high-speed mixer in proportion and mixing them evenly, then passing them through a plastic internal mixer for high-temperature mixing, a conical twin-screw feeding device for shearing and compression, a single-screw extruder for extrusion, and cooling and granulation.

5. The method for preparing the easily die-cut and easily peelable polyolefin film for patch packaging according to claim 4, characterized in that, The mixing temperature of the plastic internal mixer is 100℃; the conical twin-screw feeding device is heated in stages, with the first stage heating temperature being 125℃, the second stage heating temperature being 158℃, the third stage heating temperature being 190℃, and the fourth stage heating temperature being 210℃; the single-screw extruder is heated in stages, with the first stage heating temperature being 195℃, the second stage heating temperature being 195℃, the third stage heating temperature being 175℃, and the fourth stage heating temperature being 160℃.

6. The method for preparing the easily die-cut and easily peelable polyolefin film for patch packaging according to claim 3, characterized in that, The raw materials for the high-temperature resistant surface layer, UV-resistant functional layer, first easy-to-die-cut functional layer, second easy-to-die-cut functional layer, and easy-to-peel heat-seal layer are set at the following temperatures during the segmented heating process in the extruder: the first segment heating temperature is 60℃, the second segment heating temperature is 175℃, and the third to seventh segments heating temperatures are 210℃.

7. The method for preparing the easily die-cut and easily peelable polyolefin film for patch packaging according to claim 3, characterized in that, The set temperatures for the raw materials of the first and second adhesive layers in the segmented heating of the extruder are as follows: the heating temperature of the first segment is 50°C, the heating temperature of the second segment is 165°C, and the heating temperatures of the third to seventh segments are 225°C.

8. The method for preparing the easily die-cut and easily peelable polyolefin film for patch packaging according to claim 3, characterized in that, The set temperatures for the raw material of the intermediate barrier layer in the segmented heating of the extruder are: 50°C for the first segment, 175°C for the second segment, and 215°C for the third to seventh segments.

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