Scratch-resistant pre-coating film and preparation method thereof

Abstract

The invention provides a scratch-resistant pre-coating film and a preparation method thereof, and relates to the technical field of preparation of functional films. The scratch-resistant pre-coating film sequentially comprises a wear-resistant layer, a core layer, a secondary surface layer and an inner surface layer from top to bottom, and the wear-resistant layer comprises 5-10 parts of polyethylene, 2-4 parts of polypropylene, 0.1-0.2 part of organic peroxide, 0.02-0.04 part of divinyl benzene and 0.1-0.2 part of modified filler. The prepared scratch-resistant pre-coating film has excellent wear resistance, and meets the requirements of electronic products such as mobile phones, computers and the like on the wear resistance of packaging materials.

Description

Technical Field

[0001] The invention relates to the technical field of functional film preparation, and in particular to a scratch-resistant pre-coated film and a preparation method thereof. Background Art

[0002] BOPP is the abbreviation of biaxially oriented polypropylene film. It is colorless, odorless, tasteless, non-toxic, and has high tensile strength, impact strength, rigidity, toughness and good transparency. Therefore, it is widely used in the outer packaging of products such as bread, clothes, shoes and socks, as well as the cover packaging of cigarettes and books.

[0003] With the development of science and technology, electronic products such as mobile phones and computers have entered thousands of households and become necessities in people's daily lives. However, electronic products are prone to mutual wear and scratches 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 technicians in this field need to solve urgently. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies of the prior art, the present invention provides a scratch-resistant pre-coated film and a preparation method thereof, which solves the technical problem that the wear resistance of the existing packaging materials cannot meet the use requirements.

[0006] (II) Technical solution

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

[0008] In the first aspect, the present invention provides a scratch-resistant pre-coated film, which includes, from top to bottom, a wear-resistant layer, a core layer, a sub-surface layer and an inner surface layer, wherein the wear-resistant layer includes 5-10 parts of polyethylene, 2-4 parts of polypropylene, 0.1-0.2 parts of organic peroxide, 0.02-0.04 parts of divinylbenzene, and 0.1-0.2 parts of modified filler.

[0009] Preferably, the preparation method of the modified filler comprises:

[0010] The inorganic filler and the acid aqueous solution are mixed in a mass ratio of 1:1-1.5 and pretreated for 60-80 minutes, dehydrated and washed with water to neutrality, and then 1.5%-2.0% coupling agent accounting for the weight of the inorganic filler is added, water is added, stirred and soaked for 24-30 hours, and then dried to obtain the modified filler.

[0011] Preferably, the inorganic filler is selected from clay, BaTiO 3 、SrTiO 3 At least one of .

[0012] Preferably, the coupling agent is selected from any one of a sulfonyl azide silane coupling agent and a titanate coupling agent.

[0013] Preferably, the aqueous acid solution includes at least one of an aqueous hydrochloric acid solution and an aqueous hydrofluoric acid solution.

[0014] Preferably, the divinylbenzene is p-divinylbenzene;

[0015] The organic peroxide includes any one of diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, benzoyl peroxide, and lauroyl peroxide.

[0016] Preferably, the sub-surface layer comprises 6-12 parts of polypropylene, 1-2 parts of polyamide and 1.5-3 parts of low-density polyethylene.

[0017] Preferably, the inner surface layer comprises 10-20 parts of low-density polyethylene and 0.001-0.002 parts of a lubricant.

[0018] Preferably, the lubricant is selected from any one of erucamide and oleamide.

[0019] In a second aspect, the present invention provides a method for preparing the scratch-resistant pre-coated film according to the first aspect, comprising the following steps:

[0020] (1) Mixing polyethylene and polypropylene, and then mixing organic peroxide, p-divinylbenzene, and modified filler, and discharging the mixture uniformly, extruding and granulating to form a wear-resistant layer masterbatch; mixing polypropylene resin, polyamide resin, and low-density polyethylene uniformly, and extruding and granulating to obtain a sub-surface masterbatch; mixing low-density polyethylene and a lubricant uniformly, and extruding and granulating to obtain a bonding layer masterbatch;

[0021] (2) taking the wear-resistant layer masterbatch, high-density polypropylene particles, the sub-surface layer masterbatch, and the bonding layer masterbatch respectively, and putting them into corresponding hoppers, and extruding a four-layer co-extruded thick sheet through a four-layer co-extruder;

[0022] (3) The four-layer co-extruded thick sheet is stretched in the longitudinal and transverse directions to a film with a thickness of 0.015-0.25 mm, which is a scratch-resistant pre-coated film.

[0023] (III) Beneficial effects

[0024] The present invention provides a scratch-resistant pre-coated film and a preparation method thereof. Compared with the prior art, the present invention has the following beneficial effects:

[0025] The scratch-resistant pre-coated film of the present invention comprises a wear-resistant layer, a core layer, a sub-surface layer and an inner surface layer from top to bottom, wherein the wear-resistant layer comprises 5-10 parts of polyethylene, 2-4 parts of polypropylene, 0.1-0.2 parts of organic peroxide, 0.02-0.04 parts of divinylbenzene and 0.1-0.2 parts of modified filler. The inorganic filler and the aqueous solution of the acid are mixed in a mass ratio of 1:1-1.5 and pre-treated for 60-80 minutes, washed with water to neutrality after dehydration, and then 1.5%-2.0% coupling agent accounting for the weight of the inorganic filler is added, water is added, stirred and soaked for 24-30 hours, and then dried to prepare the modified filler. The modified inorganic filler has improved dispersibility after modification, thereby improving the wear resistance and ink adhesion of the wear-resistant layer. Therefore, the scratch-resistant pre-coated film prepared by the present invention has excellent wear resistance and ink adhesion. DETAILED DESCRIPTION

[0026] 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.

[0027] The embodiments of the present application provide a scratch-resistant pre-coated film and a preparation method thereof, thereby solving the technical problem that the wear resistance of existing packaging materials cannot meet the use requirements, and realizing the use of biaxially oriented polypropylene film to package mobile phones, computers and other electronic products, thereby preventing mobile phones, computers and other electronic products from being worn and scratched against each other during transportation and storage.

[0028] The technical solution in the embodiment of the present application is to solve the above technical problems, and the overall idea is as follows:

[0029] The present invention provides a scratch-resistant pre-coating film, which includes a wear-resistant layer, a core layer, a sub-surface layer and an inner surface layer from top to bottom, wherein the wear-resistant layer includes 5-10 parts of polyethylene, 2-4 parts of polypropylene, 0.1-0.2 parts of organic peroxide, 0.02-0.04 parts of divinylbenzene, and 0.1-0.2 parts of modified filler, and the dispersibility of the inorganic filler is improved after modification, thereby improving the wear resistance and ink adhesion of the wear-resistant layer, so that the scratch-resistant pre-coating film prepared by the present invention has excellent wear resistance and ink adhesion. Divinylbenzene has a dispersing effect on organic peroxide, so that the cross-linking effect of polyethylene, polypropylene and modified inorganic filler is uniform through heat treatment, and a wear-resistant layer resin with excellent wear resistance is obtained, thereby improving the wear resistance and ink adhesion of the scratch-resistant pre-coating film, meeting the requirements of mobile phones, computers and other electronic products for the wear resistance of packaging materials, and the effect of divinylbenzene on divinylbenzene is better than that of ortho- and meta-divinylbenzene.

[0030] 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.

[0031] Example 1

[0032] This embodiment provides a method for preparing a scratch-resistant pre-coated film, comprising the following steps:

[0033] (1) Weighing 5 kg of polyethylene and 2 kg of polypropylene, placing them in a mixing mixer, stirring for 10 minutes, then weighing 0.1 kg of diisopropyl peroxydicarbonate and 0.02 kg of p-divinylbenzene, adding them to the mixer, stirring for 10 minutes, then weighing 0.1 kg of modified clay, adding them to the mixer, mixing evenly and discharging the materials, the extruder used is a single-screw extruder, the temperature of each section of the barrel and the die is controlled at 150° C., 180° C., 210° C., 200° C., and 195° C., extruding and granulating to form a masterbatch of a wear-resistant layer;

[0034] 6 kg of polypropylene resin, 1 kg of polyamide resin and 1.5 kg of low-density polyethylene were weighed and mixed evenly, and extruded into granules. The extruder used was a single-screw extruder, and the temperatures of the barrel and the die were controlled at 160° C., 190° C., 220° C., 210° C. and 205° C. to obtain a sub-surface masterbatch;

[0035] 10 kg of low-density polyethylene and 0.1 kg of erucamide were weighed and mixed evenly, and extruded into granules. The extruder used was a single-screw extruder, and the temperatures of the barrel and the head were controlled at 140° C., 170° C., 200° C., 190° C., and 185° C. to obtain a bonding layer masterbatch.

[0036] The preparation method of modified clay comprises the following steps:

[0037] Clay and a mixed aqueous solution containing 0.5% HCL + 0.1% HF were mixed in a mass ratio of 1:1 and stirred and soaked in a stirring and soaking machine for 60 minutes. After dehydration, the mixture was washed with water until neutral. Then, 1.5% sulfonyl azide silane coupling agent based on the mass of the clay was added, and the same volume of water as the above-mentioned formula solution was added. After stirring and soaking for 24 hours, the mixture was dehydrated and dried to obtain modified clay.

[0038] (2) Weigh 5 kg, 3 kg, 2 kg, and 1 kg of wear-resistant layer masterbatch, high-density polypropylene particles, sub-surface masterbatch, and bonding layer masterbatch, respectively, and put them into corresponding hoppers, then mix them, and plasticize the mixed raw materials in a four-layer co-extruder. The processing temperature of the four-layer co-extruder is 250° C. The weight of the raw materials passing through the extruder per unit time is counted, and the speed of the extruder and the pressure of the die outlet are adjusted by the speed of the metering pump to keep the raw materials flowing out of the die stable. After metering, the raw materials flow into the filter, and the raw materials are filtered and impurities are removed before extrusion. After extrusion, the extruded materials are first tightly attached to the chilled roller by an air knife and an air nozzle, and then the extruded materials are quickly cooled by the low temperature of the water tank and the chilled roller. The temperature of the chilled roller and the water tank is 30° C. to obtain a thick sheet;

[0039] (3) The thick sheet is stretched longitudinally and transversely to obtain a film with a thickness of 0.015 mm, and then the scratch-resistant pre-coated film is obtained through processes such as traction and winding. The properties of the scratch-resistant pre-coated film are shown in Table 1.

[0040] The stretching process is as follows:

[0041] Longitudinal stretching: The rollers for longitudinal stretching use separate temperature control for the upper and lower layers to reduce the damage to the film surface caused by the different materials of the upper and lower layers of the thick film. The temperature of the longitudinal stretching preheating zone is 110°C and the stretching ratio is 4.5.

[0042] Transverse stretching: Adopt sticky clip and track width change to achieve stretching. The preheating temperature of transverse stretching is 170℃, the stretching temperature is 155℃, the setting temperature is 165℃, the air cooling in the workshop is adopted, the stretching ratio is 9, the duration of the stretching area is 2 seconds, the width of the setting section and the cooling section is gradually shrunk, and the total shrinkage is 6%, so that the film after stretching has good thermal stability;

[0043] Traction: Flatten, trim, corona, cool, measure thickness, and eliminate static electricity on the stretched film.

[0044] Winding: The film after traction is rolled into a uniform large film roll. The flatness and tightness of the large film roll are maintained by controlling the tension of the contact roller and the pressure roller. It is also responsible for recording the length of the large film roll, displaying the density, and changing the roll.

[0045] Aging: Aging the rolled film for 24 hours to increase the performance stability of the film.

[0046] The test method is as follows:

[0047] Wear resistance: The test was conducted 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 percentage of mass reduction of the scratch-resistant pre-coated film before and after friction was measured to judge its wear resistance.

[0048] Mass reduction percentage = |final sample mass value - initial sample mass value| / initial sample mass value × 100%.

[0049] Ink adhesion test: The black ink is transferred to the surface of the scratch-resistant pre-coated film by letterpress printing. After the ink is fixed, the ink adhesion is tested according to the GB / T 7706 letterpress decoration printing standard. The number of frictions is set at 900 times. According to the initial color density value and the final color density value, the ink wear resistance of the sample, i.e., the ink adhesion, is calculated. The ink adhesion of this application is expressed as the percentage of ink layer density reduction. The test results are shown in Table 1.

[0050] Ink layer density reduction percentage = |final color density value-initial color density value| / initial color density value×100%.

[0051] Other properties were carried out according to conventional methods.

[0052] Example 2

[0053] This embodiment provides a method for preparing a scratch-resistant pre-coated film, comprising the following steps:

[0054] (1) Weigh 7 kg of polyethylene and 3 kg of polypropylene, place them in a mixer and mix them for 10 minutes. Then weigh 0.15 kg of dicyclohexyl peroxydicarbonate and 0.03 kg of p-divinylbenzene and add them to the mixer and stir for 10 minutes. Then weigh 0.15 kg of modified BaTiO 3 Add the mixer and mix evenly to discharge the material. The extruder used is a single screw extruder. The temperature of each section of the barrel and the die is controlled at 150°C, 180°C, 210°C, 200°C, and 195°C. Extrusion granulation is performed to form a wear-resistant layer masterbatch.

[0055] Weigh 10 kg of polypropylene resin, 1.5 kg of polyamide resin and 2.0 kg of low-density polyethylene, mix them evenly, extrude and granulate them to obtain a sub-surface masterbatch;

[0056] 15 kg of low-density polyethylene and 0.0015 kg of oleic acid amide were weighed and mixed evenly, and extruded into granules to obtain a bonding layer masterbatch.

[0057] Modified BaTiO 3 The preparation method comprises the following steps:

[0058] BaTiO 3 , a mixed aqueous solution containing 0.5% HCL + 0.1% HF in a mass ratio of 1:1.2 was mixed in a stirring and soaking machine for 70 minutes, washed with water to neutral after dehydration, and then BaTiO 3The modified BaTiO 3 .

[0059] (2) Weigh 7 kg, 5 kg, 3 kg, and 1.5 kg of wear-resistant layer masterbatch, high-density polypropylene particles, sub-surface layer masterbatch, and bonding layer masterbatch, respectively, and put them into corresponding hoppers, and extrude a four-layer co-extruded thick sheet with a thickness of 0.3 mm through a four-layer co-extruder;

[0060] (3) The thick sheet is stretched longitudinally and transversely in sequence to obtain a thin film with a thickness of 0.018 mm, thereby obtaining a scratch-resistant pre-coated film. The properties of the scratch-resistant pre-coated film are shown in Table 1.

[0061] Other specific processes are the same as in Example 1.

[0062] Example 3

[0063] This embodiment provides a method for preparing a scratch-resistant pre-coated film, comprising the following steps:

[0064] (1) Weigh 10 kg of polyethylene and 4 kg of polypropylene, place them in a mixer and mix them for 10 minutes. Then weigh 0.2 kg of benzoyl peroxide and 0.04 kg of p-divinylbenzene and add them to the mixer and stir for 10 minutes. Then weigh 0.2 kg of modified SrTiO 3 Add the mixer and mix evenly to discharge the material. The extruder used is a single screw extruder. The temperature of each section of the barrel and the die is controlled at 150°C, 180°C, 210°C, 200°C, and 195°C. Extrusion granulation is performed to form a wear-resistant layer masterbatch.

[0065] Weigh 12 kg of polypropylene resin, 2 kg of polyamide resin and 3 kg of low-density polyethylene, mix them evenly, extrude and granulate them to obtain a sub-surface masterbatch;

[0066] 20 kg of low-density polyethylene and 0.002 kg of erucamide were weighed and mixed evenly, and extruded into granules to obtain a bonding layer masterbatch.

[0067] Modified SrTiO 3 The preparation method comprises the following steps:

[0068] SrTiO 3 , a mixed aqueous solution containing 0.5% HCL + 0.1% HF in a mass ratio of 1:1.5 was mixed in a stirring and soaking machine for 80 minutes, washed with water to neutral after dehydration, and then SrTiO 3 The same volume of water as the above solution was added to a 2.0% sulfonyl azide silane coupling agent, stirred and soaked for 30 hours, and then dehydrated and dried to obtain the modified SrTiO 3.

[0069] (2) Weighing 10 kg, 6 kg, 4 kg, and 2 kg of wear-resistant layer masterbatch, high-density polypropylene particles, sub-surface layer masterbatch, and bonding layer masterbatch, respectively, and placing them in corresponding hoppers, and extruding thick sheets through a four-layer co-extruder;

[0070] (3) The thick sheet is stretched longitudinally and transversely in sequence to obtain a film with a thickness of 0.25 mm, thereby obtaining a scratch-resistant pre-coated film. The properties of the scratch-resistant pre-coated film are shown in Table 1.

[0071] Other specific processes are the same as in Example 1.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that clay is used instead of modified clay to prepare the wear-resistant layer masterbatch, and the rest is the same as Example 1.

[0074] Comparative Example 2

[0075] The difference between this comparative example and Example 1 is that o-divinylbenzene is used instead of p-divinylbenzene to prepare the wear-resistant layer masterbatch, and the rest is the same as Example 1.

[0076] Comparative Example 3

[0077] The difference between this comparative example and Example 1 is that m-divinylbenzene is used instead of p-divinylbenzene to prepare the wear-resistant layer masterbatch, and the rest is the same as Example 1.

[0078] Table 1 Test results of scratch-resistant pre-coated films prepared in Examples and Comparative Examples

[0079]

[0080]

[0081] As can be seen from Table 1, compared with Example 1, Comparative Example 1 improves the dispersibility of the inorganic filler in polyethylene and polypropylene after modification, thereby improving the wear resistance of the wear-resistant layer masterbatch and the ink adhesion.

[0082] Compared with Example 1, in Comparative Examples 2 and 3, p-divinylbenzene is better than o-divinylbenzene and m-divinylbenzene in dispersing organic peroxides. By heat treating p-divinylbenzene, the cross-linking effect of polyethylene, polypropylene and modified inorganic filler is more uniform, thereby achieving the best abrasion resistance and ink adhesion of the scratch-resistant pre-coated film made of p-divinylbenzene.

[0083] 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.

[0084] 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.

[0085] 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 scratch-resistant pre-coated film, characterized in that: It includes a wear-resistant layer, a core layer, a sub-surface layer and an inner surface layer from top to bottom. The wear-resistant layer includes 5-10 parts of polyethylene, 2-4 parts of polypropylene, 0.1-0.2 parts of organic peroxide, 0.02-0.04 parts of divinylbenzene and 0.1-0.2 parts of modified filler.

2. The scratch-resistant pre-coated film according to claim 1, characterized in that: The preparation method of the modified filler comprises: The inorganic filler and the acid aqueous solution are mixed in a mass ratio of 1:1-1.5 and pretreated for 60-80 minutes, dehydrated and washed with water to neutrality, and then 1.5%-2.0% coupling agent accounting for the weight of the inorganic filler is added, water is added, stirred and soaked for 24-30 hours, and then dried to obtain the modified filler.

3. The scratch-resistant pre-coated film according to claim 2, characterized in that: The inorganic filler is selected from at least one of clay, BaTiO3, and SrTiO3.

4. The scratch-resistant pre-coated film according to claim 2, characterized in that: The coupling agent is selected from any one of a silane coupling agent and a titanate coupling agent.

5. The scratch-resistant pre-coated film according to claim 2, characterized in that: The acid aqueous solution includes at least one of a hydrochloric acid aqueous solution and a hydrofluoric acid aqueous solution.

6. The scratch-resistant pre-coated film according to claim 1, characterized in that: The divinylbenzene is p-divinylbenzene; The organic peroxide includes any one of diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, benzoyl peroxide, and lauroyl peroxide.

7. The scratch-resistant pre-coated film according to claim 1, characterized in that: The sub-surface layer comprises 6-12 parts of polypropylene, 1-2 parts of polyamide and 1.5-3 parts of low-density polyethylene.

8. The scratch-resistant pre-coated film according to claim 1, characterized in that: The inner surface layer comprises 10-20 parts of low-density polyethylene and 0.001-0.002 parts of a lubricant.

9. The scratch-resistant pre-coated film according to claim 8, characterized in that: The lubricant is selected from any one of erucamide and oleamide.

10. A method for preparing a scratch-resistant pre-coated film according to any one of claims 1 to 9, characterized in that: The steps include: (1) Mixing polyethylene and polypropylene, and then mixing organic peroxide, divinylbenzene, and modified filler, and discharging the mixture uniformly, extruding and granulating to form a wear-resistant layer masterbatch; mixing polypropylene resin, polyamide resin, and low-density polyethylene uniformly, and extruding and granulating to obtain a sub-surface masterbatch; mixing low-density polyethylene and a lubricant uniformly, and extruding and granulating to obtain a bonding layer masterbatch; (2) taking the wear-resistant layer masterbatch, high-density polypropylene particles, the sub-surface layer masterbatch, and the bonding layer masterbatch respectively, and putting them into corresponding hoppers, and extruding a four-layer co-extruded thick sheet through a four-layer co-extruder; (3) The four-layer co-extruded thick sheet is stretched in the longitudinal and transverse directions to a film with a thickness of 0.015-0.25 mm, which is a scratch-resistant pre-coated film.

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