Surface protective film and method for manufacturing the same and use thereof

Abstract

The present application relates to surface protection film and its preparation method and application. The surface protection film comprises three layers of A, B and C from inside to outside; wherein, the A layer comprises low density polyethylene and linear polyethylene blend composition; the B layer comprises linear polyethylene and high density polyethylene blend composition; the C layer comprises high density polyethylene, linear polyethylene, thermoplastic elastomer and silicone elastomer blend composition. The provided surface protection film will not produce film printing on the product surface, and will not scratch the product surface, especially in the scene application of transportation, stacking, loading and unloading, thereby playing an effective protection role on the surface of the product.

Description

Technical Field

[0001] This invention relates to surface protective films, their preparation methods, and applications. Background Technology

[0002] Surface protective films can be used for surface protection of products, such as scratch resistance, dust protection, and moisture protection. Surface protective films can be used in various scenarios including product packaging, transportation, stacking, loading and unloading, and use. The specific surface protective films required for each product or scenario may vary slightly. Currently, most existing surface protective films require the use of opening agents, which can easily scratch the product surface; and under friction and high temperatures, a certain amount of film can transfer, forming a "film mark" on the product surface. Summary of the Invention

[0003] To address the aforementioned problems, the core innovation of this invention lies in providing a surface protective film, its preparation method, and its application. The provided surface protective film does not leave film marks on the product surface and does not scratch the product surface, especially in applications involving transportation, stacking, and loading / unloading, thus effectively protecting the product surface.

[0004] To achieve the aforementioned technical effects, the first aspect of the present invention provides a surface protective film, which comprises three layers A, B, and C from the inside out; wherein,

[0005] Layer A consists of a blend of low-density polyethylene and linear polyethylene; Layer B consists of a blend of linear polyethylene and high-density polyethylene; Layer C comprises a blend of high-density polyethylene, linear polyethylene, thermoplastic elastomer, and silicone elastomer.

[0006] Preferably, layer A further includes a stiffening agent; the weight ratio of low-density polyethylene, linear polyethylene and stiffening agent in layer A is (12~18):(3~5):1; preferably the weight ratio is 15:4:1.

[0007] Preferably, the weight ratio of linear polyethylene to high-density polyethylene in layer B is (0.8~1.2):1; more preferably, the weight ratio is 1:1.

[0008] Preferably, the weight ratio of high-density polyethylene, linear polyethylene, thermoplastic elastomer and silicone elastomer in layer C is 1:(1~1.5):(1~1.5):1; more preferably, the weight ratio is 1:1.5:1.5:1.

[0009] Preferably, the thickness ratio of the three layers A, B, and C is A:B:C = 3:3:(3~4); more preferably, the thickness ratio is A:B:C = 3:3:4.

[0010] Preferably, the stiffening agent is dibenzyl sorbitol and its derivatives.

[0011] This application also provides a second aspect of the technical solution, namely, a method for preparing any of the aforementioned surface protective films, which includes mixing and granulating the components of the three layers A, B, and C separately, and then extruding them by a blown film machine to form a surface protective film consisting of three layers A, B, and C from the inside out.

[0012] Preferably, the mixing and granulation of the C-layer components are carried out using the following steps:

[0013] 1) Blend high-density polyethylene and linear polyethylene together;

[0014] 2) Blend the thermoplastic elastomer with the silicone elastomer, then blend it with the mixture in step 1), and then granulate it underwater.

[0015] Preferably, the mixing and granulation of the components in layer A are carried out using the following steps:

[0016] Low-density polyethylene and linear polyethylene are blended and stirred, and then granulated underwater.

[0017] Preferably, the mixing and granulation of the B-layer components are carried out using the following steps:

[0018] Linear polyethylene and high-density polyethylene are blended and stirred, and then granulated underwater.

[0019] This application also provides a third technical solution, namely the application of any of the aforementioned surface protective films, including the use of the surface protective film to wrap the product surface in scenarios such as transportation, stacking, loading and unloading, with the C-layer serving as the contact surface with the product surface.

[0020] The linear polyethylene described in this application is a thermoplastic polymer with a linear main chain structure formed by polymerization of ethylene as a monomer. Its molecular chains are linear with few or short branches. The linear polyethylene described in this application is manufactured using ethylene as the main raw material through polymerization. Preferably, it is linear polyethylene that does not contain other components or contains only a small amount of impurities, and more preferably, it is linear polyethylene with a branched chain content of less than 2%.

[0021] The low-density polyethylene described in this application is also a thermoplastic polymer with low density formed by polymerization of ethylene as a monomer. Its molecular chain can be linear or non-linear. Compared to linear polyethylene, there are no special requirements for the molecular chain structure, but the density is relatively low, preferably 0.910~0.940 g / cm³. 3 The low-density polyethylene described in this application is manufactured using ethylene as the main raw material through a polymerization process. Preferably, it is low-density polyethylene that does not contain other components or contains only a small amount of impurities.

[0022] The high-density polyethylene described in this application is also a high-density thermoplastic polymer formed by polymerization of ethylene as a monomer. Its molecular chains can be linear or non-linear. Compared to linear polyethylene, there are no special requirements for the molecular chain structure, but the density is relatively high, preferably 0.940~0.976 g / cm³. 3 High-density polyethylene. The high-density polyethylene described in this application is manufactured by polymerization process using ethylene as the main raw material, and preferably contains no other components or contains only a small amount of impurities.

[0023] The thermoplastic elastomers TPE / TPR described in this application are also known as synthetic rubber or artificial rubber. These products possess the excellent properties of traditional cross-linked vulcanized rubber, including high elasticity, aging resistance, and oil resistance, while also having the advantages of ordinary plastics, such as ease of processing and a wide range of processing methods.

[0024] The silicone elastomer described in this application is a material composed of a linear polymer, a reinforcing agent, a crosslinking agent, and a catalyst, possessing excellent mechanical properties and high-temperature resistance. The silicone elastomer can be, for example, silicone rubber.

[0025] The stiffening agent described in this application is a functional additive mainly used to improve the rigidity and mechanical properties of polymer materials, and is widely used in the production of plastic products. The stiffening agent is preferably a sorbitol-based substance, such as dibenzyl sorbitol and its derivatives, abbreviated as DBS.

[0026] All the ingredients described in this application are commercially available, and unless otherwise specified, a purity of 98% or higher is preferred.

[0027] The equipment used in the preparation method provided in this application are all conventional laboratory or factory equipment.

[0028] Unless otherwise specified, all units of measurement used in this application are by weight or weight percentage.

[0029] The surface protective film provided in this application has the following advantages:

[0030] When wrapping products, it will not leave film marks or scratch the product surface;

[0031] No opening agent is needed, and the openings separate well. Attached Figure Description

[0032] Figure 1 These are the microscopic views of the surface protective films in Examples 1-3;

[0033] Figure 2 This is a comparison of the surface protective film displayed under a microscope;

[0034] Figure 3 This application includes a schematic diagram of a product wrapped with a surface protective film.

[0035] Figure 4 This product has undergone drop testing.

[0036] Figure 5 It is a product that has undergone drop testing after being packaged with existing conventional surface protective films. Detailed Implementation

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0039] It should be noted that the terms "first," "second," etc., used in this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate for the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0040] I. Preparation of the surface protective film of this application

[0041] Preparation of A-layer particles:

[0042] Low-density polyethylene, linear polyethylene, and stiffening agent are blended and stirred in a weight ratio of D1, and then granulated underwater.

[0043] Preparation of B-layer particles:

[0044] Linear polyethylene and high-density polyethylene are blended and stirred in a weight ratio of D2, and then granulated underwater.

[0045] Preparation of C-layer particles:

[0046] 1) Blend high-density polyethylene and linear polyethylene in a weight ratio of D3;

[0047] 2) Blend the thermoplastic elastomer and silicone elastomer in a weight ratio of D4, then blend them in equal weight with the mixture in step 1), and then granulate them underwater.

[0048] Preparation of surface protective film:

[0049] The particles of the three layers A, B, and C are fed into different inlets of the blown film machine and co-extruded by the blown film machine to form a surface protective film of three layers A, B, and C from the inside out; the thickness ratio of each layer of the blown film machine is set to F, and the overall thickness of the film is 0.1~0.5mm.

[0050] The following table shows the detailed values ​​for each of the stated proportions:

[0051] II. Basic Performance

[0052] The surface protective films of Test Examples 1-3 were placed under the following corresponding temperature and humidity conditions for 24 hours to determine their condition.

[0053] Temperature: 18~33℃;

[0054] Relative humidity: 30-80%RH.

[0055] Test results:

[0056] The surface protective films in Examples 1-3 showed no abnormalities and met the requirements after 24 hours of pretreatment in an environment with a temperature of 18-33°C and a humidity of 30-80%RH.

[0057] The surface protective films of Test Examples 1-3 and the conventional existing surface protective films (e.g., polyethylene) of the comparative examples are shown under a microscope. Specific test results can be found in [reference needed]. Figure 1 and Figure 2 ;in, Figure 1 These are the microscopic views of the surface protective films in Examples 1-3. Figure 2 The figures show the surface protective films in a comparative manner under a microscope. As can be seen from the figures, the surface protective films provided in Examples 1-3 of this application are denser and have fewer particles in a microscopic state. This provides better protection and scratch resistance for the product surface and makes it less likely to leave film marks on the product surface.

[0058] III. Stacking Test

[0059] The surface protective film A from Examples 1-3 was used to wrap the outer surface of product B. During wrapping, layer C of the surface protective film A was wrapped around the outer surface of product B. After wrapping the surface protective film A with cushioning packaging C, the product was sealed in a cardboard box D to form a test sample. Figure 3As shown. Product B can be, for example, an electric kettle. Before testing, the product's structure, appearance, and function were all normal.

[0060] Before testing, calculate the load weight when stacking according to the formula: F=1.5×(N-1)×M.

[0061] F: Total weight of the stacking test

[0062] 1.5: Deterioration coefficient during distribution

[0063] M: Weight of the packaging unit

[0064] N: For single-layer packaging, N is 16; for double-layer packaging, N is 8.

[0065] Apply the load evenly to the packaging and maintain it for 48 hours. After the test, check the packaging and the prototype for any abnormalities.

[0066] Test results:

[0067] M = 1.17 kg;

[0068] N=16

[0069] F=1.5×(16-1)×M=26.33kg.

[0070] The samples were stacked for 48 hours for testing.

[0071] After testing, remove the electric kettle, observe its outer surface, and test its electrical safety performance and functionality.

[0072] Test results:

[0073] IV. Vibration Test

[0074] The surface protective film A from Examples 1-3 was used to wrap the outer surface of product B. During wrapping, layer C of the surface protective film A was wrapped around the outer surface of product B. After wrapping the surface protective film A with cushioning packaging C, the product was sealed in a cardboard box D to form a test sample. Figure 3 As shown. Product B can be, for example, an electric kettle. Before testing, the product's structure, appearance, and function were all normal.

[0075] Place the test sample on the vibration table as required. Set the amplitude to 25mm and adjust the vibration frequency (usually around 5Hz) until the packaging bounces slightly on the table. Use a steel ruler to check if the vibration meets the requirements. The steel ruler should be able to pass smoothly through the bottom of the packaging. Test surfaces 3, 4, and 6 - which correspond to different surfaces of the test sample, i.e., the cardboard box. Vibrate each surface for 60 minutes.

[0076] After testing, remove the electric kettle, observe its outer surface, and test its electrical safety performance and functionality.

[0077] Test results:

[0078] V. Drop Test (1.2m, one corner, three-sided, six-faceted)

[0079] The surface protective film A from Examples 1-3 was used to wrap the outer surface of product B. During wrapping, layer C of the surface protective film A was wrapped around the outer surface of product B. After wrapping the surface protective film A with cushioning packaging C, the product was sealed in a cardboard box D to form a test sample. Figure 3 As shown. Product B can be, for example, an electric kettle. Before testing, the product's structure, appearance, and function were all normal.

[0080] For products with a single snap-locking mechanism, they must be placed at -5°C for 4 hours before being subjected to a drop test.

[0081] Fall height: 1.2m.

[0082] Falling sequence: weakest angle (angle 2-3-5) → shortest side of angle 2-3-5 → second longest side of angle 2-3-5 → longest side of angle 2-3-5 → smallest area face → opposite face → second largest area face → opposite face → largest area face → opposite face.

[0083] After testing, remove the electric kettle, observe its outer surface, and test its electrical safety performance and functionality.

[0084] Test results:

[0085] VI. Roller Test

[0086] The surface protective film A from Examples 1-3 was used to wrap the outer surface of product B. During wrapping, layer C of the surface protective film A was wrapped around the outer surface of product B. After wrapping the surface protective film A with cushioning packaging C, the product was sealed in a cardboard box D to form a test sample. Figure 3 As shown. Product B can be, for example, an electric kettle. Before testing, the product's structure, appearance, and function were all normal.

[0087] Keep one side of the hexagonal roller tester horizontal, place the test sample with one side facing up, and place its two and five sides along the guide plate on the one side of the hexagonal roller tester. Then start the test and roll and drop 50 times.

[0088] After testing, remove the electric kettle, observe its outer surface, and test its electrical safety performance and functionality.

[0089] Test results:

[0090] VII. Drop Test (1.5m six-sided drop)

[0091] The surface protective film A of Examples 1-3 and the conventional existing surface protective film of the comparative example were respectively wrapped around the outer surface of product B. During wrapping, layer C of surface protective film A was wrapped around the outer surface of product B, and cushioning packaging C was wrapped around the outer perimeter of the surface protective film (examples and comparative examples). Then, the product was sealed in a cardboard box D to form a test sample. Figure 3 As shown. Product B can be, for example, an electric kettle. Before testing, the product's structure, appearance, and function were all normal.

[0092] For products with a single snap-locking mechanism, they must be placed at -5°C for 4 hours before being subjected to a drop test.

[0093] Fall height: 1.5m

[0094] Three test samples (each corresponding to Examples 1-3) were each subjected to two (symmetrical) drops, for a total of six drops:

[0095] Test sample 1# (corresponding to the surface protective film of Example 1): Surface 1, Surface 3

[0096] Test sample 2# (corresponding to the surface protective film of Example 2): Surface 2, Surface 4

[0097] Test sample 3# (corresponding to the surface protective film of Example 3): Surface 5, Surface 6

[0098] After testing, remove the electric kettle, observe its outer surface, and test its electrical safety performance and functionality.

[0099] Test results:

[0100] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A surface protective film, characterized in that, It includes three layers, A, B, and C, from the inside out; among them, Layer A consists of a blend of low-density polyethylene and linear polyethylene; Layer B consists of a blend of linear polyethylene and high-density polyethylene; Layer C comprises a blend of high-density polyethylene, linear polyethylene, thermoplastic elastomer, and silicone elastomer.

2. The surface protective film according to claim 1, characterized in that, Layer A also includes a stiffening agent; the weight ratio of low-density polyethylene, linear polyethylene and stiffening agent in layer A is (12~18):(3~5):1; the preferred weight ratio is 15:4:

1.

3. The surface protective film according to claim 1, characterized in that, The weight ratio of linear polyethylene to high-density polyethylene in layer B is (0.8~1.2):1; preferably, the weight ratio is 1:

1.

4. The surface protective film according to claim 1, characterized in that, The weight ratio of high-density polyethylene, linear polyethylene, thermoplastic elastomer and silicone elastomer in layer C is 1:(1~1.5):(1~1.5):1; preferably, the weight ratio is 1:1.5:1.5:

1.

5. The surface protective film according to claim 1, characterized in that, The thickness ratio of the three layers A, B, and C is A:B:C = 3:3:(3~5); the preferred thickness ratio is A:B:C = 3:3:

4.

6. The method for preparing the surface protective film according to claim 1, characterized in that, The components of the three layers A, B, and C are mixed and granulated separately, and then extruded by a blown film machine to form a surface protective film consisting of three layers, A, B, and C, from the inside out.

7. The preparation method according to claim 6, characterized in that, The mixing and granulation of the C-layer components are carried out using the following steps: 1) Blend high-density polyethylene and linear polyethylene together; 2) Blend the thermoplastic elastomer with the silicone elastomer, then blend it with the mixture in step 1), and then granulate it underwater.

8. The preparation method according to claim 6, characterized in that, The mixing and granulation of the components in layer A are carried out using the following steps: Low-density polyethylene and linear polyethylene are blended and stirred, and then granulated underwater.

9. The preparation method according to claim 6, characterized in that, The mixing and granulation of the B-layer components are carried out using the following steps: Linear polyethylene and high-density polyethylene are blended and stirred, and then granulated underwater.

10. The application of the surface protective film described in claim 1, characterized in that, The surface protective film is used to wrap the product surface in scenarios such as transportation, stacking, loading and unloading, with the C-layer serving as the contact surface with the product surface.

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