Scratch-resistant high-barrier heat-sealing polyethylene film and preparation method thereof

Abstract

The invention provides a scratch-resistant high-barrier heat-sealing polyethylene film and a preparation method thereof, and relates to the technical field of polyethylene film preparation. The preparation method of the scratch-resistant high-barrier heat-sealing polyethylene film comprises the following steps: preparing a polyethylene scratch-resistant master batch, a polypropylene high-barrier master batch and a polyethylene heat-sealing master batch; extruding a four-layer co-extrusion thick film through a four-layer co-extrusion machine; the four-layer co-extrusion thick film is longitudinally and transversely stretched at a constant speed to form a film with the thickness of 0.006-0.01 mm, and the scratch-resistant high-barrier heat-sealing polyethylene film with excellent wear resistance and barrier property is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of polyethylene film preparation, and in particular to a scratch-resistant high-barrier heat-seal polyethylene film and a preparation method thereof. Background Art

[0002] BOPE is the abbreviation of Biaxially Oriented Polyethylene, which is a biaxially oriented polyethylene film. It is made of special LLDPE raw materials, and is stretched longitudinally first and then transversely. It has greatly improved physical properties compared with the polyethylene film produced by the original blow molding or cast film method. It has high transparency, good heat sealing, moisture resistance, good longitudinal and transverse tensile strength, and has the advantages of moisture resistance and foldability. Therefore, it is widely used in the outer packaging of bread, clothes, shoes and socks and the cover packaging of cigarettes and books.

[0003] However, electronic products are easily worn and scratched during transportation and storage, which affects their performance. Therefore, higher requirements are placed on the wear resistance of packaging materials used for electronic products, which has become a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a scratch-resistant high-barrier heat-seal polyethylene film and a preparation method thereof.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a scratch-resistant high-barrier heat-seal polyethylene film, comprising the following steps:

[0009] (1) polyethylene, polypropylene and modified filler are mixed uniformly and melt-granulated to obtain polyethylene scratch-resistant masterbatch; polypropylene, petroleum resin, ethylene-vinyl alcohol copolymer resin, diisopropyl peroxydicarbonate, divinylbenzene, high-density polyethylene and monoglyceride of stearic acid are mixed uniformly and melt-granulated to obtain polypropylene high-barrier masterbatch; low-density polyethylene and erucamide are mixed uniformly and melt-granulated to obtain polyethylene heat-sealing masterbatch;

[0010] (2) respectively taking the polyethylene scratch-resistant masterbatch, high-density polyethylene, the polypropylene high-barrier masterbatch, and the polyethylene heat-sealing masterbatch, and obtaining a four-layer co-extruded thick film through a co-extrusion process;

[0011] (3) The four-layer co-extruded thick film is uniformly stretched in the longitudinal and transverse directions to a film with a thickness of 0.006-0.01 mm to obtain a scratch-resistant high-barrier heat-seal polyethylene film.

[0012] Preferably, the preparation method of the modified filler comprises the following steps: adding the filler to an ethylene glycol aqueous solution and stirring and dispersing it, adjusting the pH, and then stirring and dispersing it evenly, adding silane and stirring and dispersing it evenly, heating and stirring, centrifuging, filtering and drying the precipitate to obtain the modified filler.

[0013] Preferably, the filler comprises clay or calcium carbonate.

[0014] Preferably, the mass ratio of the polyethylene, polypropylene and modified filler is 5-10:2-5:0.1-0.3 to prepare the polyethylene scratch-resistant masterbatch.

[0015] Preferably, the polypropylene, petroleum resin, ethylene-vinyl alcohol copolymer, diisopropyl peroxydicarbonate, divinylbenzene, high-density polyethylene, and stearic acid monoglyceride are mixed in a mass ratio of 10-15: 1-3: 1-3: 0.1-0.5: 0.02-0.05: 2-4: 0.2-0.5 to prepare the polypropylene high barrier masterbatch.

[0016] Preferably, the petroleum resin comprises C9-C17 petroleum resin.

[0017] Preferably, the silane comprises vinyltriethoxysilane.

[0018] In a second aspect, the present invention provides a scratch-resistant high-barrier heat-seal polyethylene film obtained by the preparation method described in the first aspect, wherein the scratch-resistant high-barrier heat-seal polyethylene film has an O2 permeability of 0.25-0.31 cm 3 / m 2 .d.pa.

[0019] Preferably, the heat sealing strength of the scratch-resistant high-barrier heat-seal polyethylene film is 16-20N / 15mm.

[0020] (III) Beneficial effects

[0021] The present invention provides a scratch-resistant high-barrier heat-seal polyethylene film and a preparation method thereof. Compared with the prior art, the present invention has the following beneficial effects:

[0022] The invention discloses a method for preparing a scratch-resistant high-barrier heat-seal polyethylene film, comprising the steps of uniformly mixing polyethylene, polypropylene and a modified filler and melt-granulating the mixture to obtain a polyethylene scratch-resistant masterbatch, wherein the filler is added into an ethylene glycol aqueous solution and stirred and dispersed, the pH value is adjusted, and then stirred and dispersed uniformly, silane is added and stirred and dispersed uniformly, the temperature is increased and stirred, centrifuged, filtered, and a precipitate is dried to obtain the modified filler, and the dispersion uniformity of the inorganic filler in the polyethylene and the polypropylene is improved through modification, thereby improving the wear resistance of the polyethylene scratch-resistant masterbatch. Therefore, the scratch-resistant high-barrier heat-seal polyethylene film prepared by the invention has excellent wear resistance and meets the requirements of electronic products for packaging materials. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with specific implementation methods.

[0025] Example 1

[0026] This embodiment provides a method for preparing a scratch-resistant high-barrier heat-seal BOPE film, comprising the following steps:

[0027] (1) 5 kg of polyethylene, 2 kg of polypropylene, and 0.1 kg of modified calcium carbonate were uniformly mixed in a plastic mixer and melt-extruded and granulated by a twin-screw extruder, and the temperatures of the barrel and the die of the extruder were controlled at 150° C., 180° C., 210° C., 200° C., and 195° C. to obtain a polyethylene scratch-resistant masterbatch; 10 kg of polypropylene resin, 1 kg of C9-C17 petroleum resin, 1 kg of ethylene-vinyl alcohol copolymer resin, 0.1 kg of diisopropyl peroxydicarbonate, 0.02 kg of divinylbenzene, 2 kg of high-density polyethylene, 0.2 10 kg of low-density polyethylene and 0.1 kg of erucamide were evenly mixed in a plastic mixer and melt-extruded into granules using a twin-screw extruder. The temperatures of the barrel and the head of the extruder were controlled at 170°C, 200°C, 230°C, 220°C and 215°C to obtain polypropylene high-barrier masterbatch. 10 kg of low-density polyethylene and 0.1 kg of erucamide were evenly mixed in a plastic mixer and melt-extruded into granules using a twin-screw extruder. The temperatures of the barrel and the head of the extruder were controlled at 140°C, 170°C, 200°C, 190°C and 185°C to obtain polyethylene heat-sealing masterbatch.

[0028] Wherein, the preparation method of modified calcium carbonate comprises the following steps:

[0029] Add 10g of calcium carbonate to 120g of 70% ethylene glycol aqueous solution at 20°C and stir to disperse, adjust the pH to 10 with 20% ammonia water, and then stir to disperse evenly, add 15g of vinyltriethoxysilane and stir to disperse evenly, heat to 45°C and stir at 300r / min for 60min, centrifuge at 6000r / min for 30min, filter and dry the precipitate at 90°C for 24h to obtain modified calcium carbonate.

[0030] (2) Weighing 5 kg, 4 kg, 2 kg, and 2 kg of polyethylene scratch-resistant masterbatch, high-density polyethylene particles, polypropylene high-barrier masterbatch, and polyethylene heat-sealing masterbatch, respectively, and placing them in corresponding hoppers, and extruding a four-layer co-extruded thick film with a thickness of 0.3 mm through a four-layer co-extruder;

[0031] (3) The four-layer co-extruded thick film was placed on a longitudinal and transverse stretching frame and stretched at a uniform speed to a film with a thickness of 0.006 mm to obtain a scratch-resistant high-barrier heat-seal BOPE film. The properties of the scratch-resistant high-barrier heat-seal BOPE film are shown in Table 1.

[0032] The test method is as follows:

[0033] Wear resistance: The film was tested according to HG / T4303-2012 standard. The total weight of the friction hammer was 100g, and the abrasive material type was 0000# steel wool. After the friction hammer was moved back and forth horizontally and linearly 50 times, the surface smoothness of the film was visually inspected.

[0034] O2 barrier property: tested according to GB / T1038-2000 standard, the unit is (cm 3 / m 2 .d.pa).

[0035] Heat seal strength: tested in accordance with QB / T2358-1998, the unit is (N / 15mm).

[0036] Example 2

[0037] This embodiment provides a method for preparing a scratch-resistant high-barrier heat-seal BOPE film, comprising the following steps:

[0038] (1) 8 kg of polyethylene, 3 kg of polypropylene, and 0.2 kg of modified clay are uniformly mixed in a plastic mixer and melt-extruded and granulated by a twin-screw extruder to obtain polyethylene scratch-resistant masterbatch; 12 kg of polypropylene resin, 2 kg of C9-C17 petroleum resin, 2 kg of ethylene-vinyl alcohol copolymer resin, 0.3 kg of diisopropyl peroxydicarbonate, 0.03 kg of p-divinylbenzene, 3 kg of high-density polyethylene, and 0.3 kg of stearic acid monoglyceride are uniformly mixed in a plastic mixer and melt-extruded and granulated by a twin-screw extruder to obtain polypropylene high-barrier masterbatch; 15 kg of low-density polyethylene and 0.3 kg of erucamide are uniformly mixed in a plastic mixer and melt-extruded and granulated by a twin-screw extruder to obtain polyethylene heat-sealing masterbatch.

[0039] The preparation method of modified clay comprises the following steps: adding 12g of clay to 125g of 75% ethylene glycol aqueous solution at 20°C and stirring and dispersing the mixture, adjusting the pH to 10 with 20% ammonia water, stirring and dispersing the mixture evenly, adding 20g of vinyl triethoxysilane and stirring and dispersing the mixture evenly, heating the mixture to 45°C and stirring the mixture at a speed of 300r / min for 60min, centrifuging the mixture at 6000r / min for 30min, filtering the mixture and drying the mixture at 90°C for 24h to obtain modified clay.

[0040] (2) Weigh 8 kg, 6 kg, 3 kg, and 3 kg of polyethylene scratch-resistant masterbatch, high-density polyethylene particles, polypropylene high-barrier masterbatch, and polyethylene heat-sealing masterbatch, respectively, and put them into corresponding hoppers, and extrude a four-layer co-extruded thick film with a thickness of 0.4 mm through a four-layer co-extruder;

[0041] (3) The four-layer co-extruded thick film was placed on a longitudinal and transverse stretching frame and stretched at a uniform speed to a film with a thickness of 0.008 mm to obtain a scratch-resistant high-barrier heat-seal BOPE film. The properties of the scratch-resistant high-barrier heat-seal BOPE film are shown in Table 1.

[0042] Example 3

[0043] This embodiment provides a method for preparing a scratch-resistant high-barrier heat-seal BOPE film, comprising the following steps:

[0044] (1) 10 kg of polyethylene, 5 kg of polypropylene, and 0.3 kg of modified calcium carbonate are uniformly mixed in a plastic mixer and melt-extruded and granulated by a twin-screw extruder to obtain polyethylene scratch-resistant masterbatch; 15 kg of polypropylene resin, 3 kg of C9-C17 petroleum resin, 3 kg of ethylene-vinyl alcohol copolymer resin, 0.5 kg of diisopropyl peroxydicarbonate, 0.05 kg of p-divinylbenzene, 4 kg of high-density polyethylene, and 0.5 kg of stearic acid monoglyceride are uniformly mixed in a plastic mixer and melt-extruded and granulated by a twin-screw extruder to obtain polypropylene high-barrier masterbatch; 20 kg of low-density polyethylene and 0.5 kg of erucamide are uniformly mixed in a plastic mixer and melt-extruded and granulated by a twin-screw extruder to obtain polyethylene heat-sealing masterbatch.

[0045] Wherein, the preparation method of modified calcium carbonate comprises the following steps:

[0046] Add 15g of calcium carbonate to 130g of 80% ethylene glycol aqueous solution at 20°C and stir to disperse, adjust the pH to 10 with 20% ammonia water, and then stir to disperse evenly, add 25g of vinyltriethoxysilane and stir to disperse evenly, heat to 45°C and stir at 300r / min for 60min, centrifuge at 6000r / min for 30min, filter and dry the precipitate at 90°C for 24h to obtain modified calcium carbonate.

[0047] (2) Weighing 10 kg, 8 kg, 4 kg, and 4 kg of polyethylene scratch-resistant masterbatch, high-density polyethylene particles, polypropylene high-barrier masterbatch, and polyethylene heat-sealing masterbatch, respectively, and putting them into corresponding hoppers, and extruding a four-layer co-extruded thick film with a thickness of 0.6 mm through a four-layer co-extruder;

[0048] (3) The four-layer co-extruded thick film was placed on a longitudinal and transverse stretching frame and stretched at a uniform speed to a film with a thickness of 0.01 mm to obtain a scratch-resistant high-barrier heat-seal BOPE film. The properties of the scratch-resistant high-barrier heat-seal BOPE film are shown in Table 1.

[0049] Comparative Example 1

[0050] The difference between this comparative example and Example 1 is that diisopropyl peroxydicarbonate is not added, the amount of divinylbenzene used is 0.022 kg, the amount of ethylene-vinyl alcohol copolymer resin used is 1.098 kg, and the high barrier masterbatch is prepared. The rest is the same as Example 1.

[0051] Comparative Example 2

[0052] The difference between this comparative example and Example 1 is that divinylbenzene is not added, the amount of diisopropyl peroxydicarbonate used is 0.102 kg, the amount of ethylene-vinyl alcohol copolymer resin used is 1.018 kg, and the high barrier masterbatch is prepared. The rest is the same as Example 1.

[0053] Comparative Example 3

[0054] The difference between this comparative example and Example 1 is that no ethylene-vinyl alcohol copolymer resin is added, the amount of divinylbenzene used is 0.19 kg, the amount of diisopropyl peroxydicarbonate used is 0.93 kg, and the high barrier masterbatch is prepared. Others are the same as in Example 1.

[0055] Comparative Example 4

[0056] The difference between this comparative example and Example 1 is that calcium carbonate is used instead of modified calcium carbonate to prepare the polyethylene scratch-resistant masterbatch, and the rest is the same as Example 1.

[0057] Table 1 Performance of scratch-resistant high-barrier heat-seal BOPE films prepared in Examples and Comparative Examples

[0058] Surface smoothness <![CDATA[O2 Permeation Rate]]> Heat seal strength Example 1 smooth 0.25 16.8 Example 2 smooth 0.31 18.5 Example 3 smooth 0.30 17.6 Comparative Example 1 smooth 1.23 17.1 Comparative Example 2 smooth 1.53 18.5 Comparative Example 3 smooth 3.89 17.9 Comparative Example 4 There are obvious scratches 0.33 17.5

[0059] As can be seen from Table 1, the wear resistance of the scratch-resistant high-barrier heat-seal BOPE film prepared in Comparative Example 4 is reduced. This is because the filler has not been modified, resulting in uneven dispersion, thereby reducing the wear resistance of the polyethylene scratch-resistant masterbatch. As can be seen from Comparative Examples 1-3, the barrier properties of the scratch-resistant high-barrier heat-seal BOPE film prepared without any of the raw materials of ethylene-vinyl alcohol copolymer resin, diisopropyl peroxydicarbonate, and divinylbenzene are poor. Therefore, ethylene-vinyl alcohol copolymer resin, diisopropyl peroxydicarbonate, and divinylbenzene have a synergistic effect in improving the barrier properties. This is because divinylbenzene has a dispersing effect on diisopropyl peroxydicarbonate, so that the cross-linking effect of ethylene-vinyl alcohol copolymer resin and polyethylene and polypropylene is uniform through heat treatment, thereby improving the barrier properties of the scratch-resistant high-barrier heat-seal polyethylene film.

[0060] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0061] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0062] The present invention illustrates the detailed process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a scratch-resistant high-barrier heat-seal polyethylene film, characterized in that: The steps include: (1) polyethylene, polypropylene and modified filler are mixed uniformly and melt-granulated to obtain polyethylene scratch-resistant masterbatch; polypropylene, petroleum resin, ethylene-vinyl alcohol copolymer resin, diisopropyl peroxydicarbonate, divinylbenzene, high-density polyethylene and monoglyceride of stearic acid are mixed uniformly and melt-granulated to obtain polypropylene high-barrier masterbatch; low-density polyethylene and erucamide are mixed uniformly and melt-granulated to obtain polyethylene heat-sealing masterbatch; (2) respectively taking the polyethylene scratch-resistant masterbatch, high-density polyethylene, the polypropylene high-barrier masterbatch, and the polyethylene heat-sealing masterbatch, and obtaining a four-layer co-extruded thick film through a co-extrusion process; (3) The four-layer co-extruded thick film is uniformly stretched in the longitudinal and transverse directions to a film with a thickness of 0.006-0.01 mm to obtain a scratch-resistant high-barrier heat-seal polyethylene film.

2. The preparation method according to claim 1, characterized in that The preparation method of the modified filler comprises the following steps: adding the filler into an ethylene glycol aqueous solution and stirring and dispersing it, adjusting the pH, stirring and dispersing it uniformly, adding silane and stirring and dispersing it uniformly, heating and stirring, centrifugally separating, filtering, and drying the precipitate to obtain the modified filler.

3. The preparation method according to claim 1 or 2, characterized in that: The filler includes clay or calcium carbonate.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the polyethylene, polypropylene and modified filler is 5-10:2-5:0.1-0.3, and the polyethylene scratch-resistant masterbatch is prepared.

5. The preparation method according to claim 1, characterized in that: The polypropylene, petroleum resin, ethylene-vinyl alcohol copolymer, diisopropyl peroxydicarbonate, divinylbenzene, high-density polyethylene and stearic acid monoglyceride are mixed in a mass ratio of 10-15: 1-3: 1-3: 0.1-0.5: 0.02-0.05: 2-4: 0.2-0.5 to prepare the polypropylene high-barrier masterbatch.

6. The preparation method according to claim 1 or 5, characterized in that: The petroleum resin includes C9-C17 petroleum resin.

7. The preparation method according to claim 1, characterized in that: The silane includes vinyltriethoxysilane.

8. A scratch-resistant high-barrier heat-seal polyethylene film obtained by the preparation method according to any one of claims 1 to 7, characterized in that: The scratch-resistant high-barrier heat-seal polyethylene film has an O2 permeability of 0.20-0.35 cm 3 / m 2 .d.pa.

9. The scratch-resistant high-barrier heat-seal polyethylene film according to claim 8, characterized in that: The heat sealing strength of the scratch-resistant high-barrier heat-seal polyethylene film is 16-20N / 15mm.