Self-adhesive protective film

Abstract

The invention discloses a self-adhesion protective film, and relates to the technical field of high polymer materials, the self-adhesion protective film comprises a self-adhesion layer, a core layer and an anti-adhesion back layer, the self-adhesion layer is prepared from ethylene, propylene, a 1-hexene copolymer and polypropylene, and the core layer and the anti-adhesion back layer are both prepared from block co-polypropylene. According to the self-adhesive protective film, the blend of the ethylene, the propylene, the 1-hexene copolymer and the polypropylene is used as the self-adhesive layer, and the polypropylene is used for changing the amount of amorphous regions formed by the ethylene, the propylene and the 1-hexene copolymer and the high temperature resistance, so that the self-adhesive layer has relatively good viscosity at normal temperature, can be adhered to the surfaces of PC and PMMA plates, but is not melted or permeated in a high-temperature forming process; the viscous force is not increased, so that no adhesive residue is generated during stripping; meanwhile, the core layer and the anti-sticking back layer take block co-polypropylene as raw materials, have better high temperature resistance and tensile property, and can meet the molding requirements of complex structures.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, in particular to a self-adhesive protective film. Background Art

[0002] PC sheets, PMMA sheets, etc. have excellent printing and thermoforming properties at high temperatures. They can be printed with a variety of colors and patterns, and can be thermoformed into various structures to meet people's increasing demand for appearance and shape. For example, gorgeous helmets, bags of various shapes, and the development of new energy vehicles in recent years, all kinds of gorgeous and unique car interiors and parts can be prepared by thermoforming after printing with PC sheets and PMMA sheets. In order to prevent scratches and contamination on the surface of the sheet during high-temperature molding, a layer of high-temperature resistant protective film is usually adhered to the surface of the sheet. Since the protective film needs to be thermoformed with the sheet during the molding process, the protective film must have good adhesion and tensile properties. However, due to the lack of high temperature resistance and tensile properties of the existing protective film, the protective film is damaged during the high-temperature molding process of the sheet, especially when the complex structure is thermoformed, and the sheet cannot be effectively protected. At the same time, during the high-temperature molding process, additives are precipitated to the surface of the finished product, and when peeled off, it is bonded to the surface of the sheet due to high temperature, leaving residual glue and oil on the surface of the finished product during peeling, resulting in pollution of the appearance of the product.

[0003] Chinese invention patent CN201711091201.7 discloses a protective film for chip cutting and a preparation method thereof. The pressure-sensitive adhesive is prepared by using modified PO material to make it highly transparent and its viscosity changes little under high temperature conditions. However, the obtained protective film has a low elongation rate and cannot meet the conditions for sheet forming.

[0004] Chinese invention patent CN202210154875.1 discloses an ultra-high temperature resistant blister forming protective film. By adding maleic anhydride modified hydrogenated styrene block copolymer, the compatibility between copolymers is improved, the cohesion of the polymer is increased, and the polymer is not easy to precipitate at high temperature. However, the invention uses maleic anhydride modified hydrogenated styrene block copolymer as the self-adhesive layer. Although the adhesion is relatively large, the filler oil added in the adhesive layer will precipitate on the surface of the sheet at high temperature, polluting the surface of the sheet, and the filler oil volatilizes and produces gas during high-temperature molding, which will cause the surface of the finished product to be uneven; in addition, the invention uses 7-95 parts of polyethylene in the middle core layer. Since the melting point of polyethylene is 100-130°C, the melting point is low. When the temperature reaches or exceeds this temperature, the inside of the protective film begins to melt, making the protective film poor in temperature resistance during the sheet thermoforming process, and cannot play a protective role. It can only be used for the molding of some simple structures, not for the molding of complex structures.

[0005] It can be seen that the existing technology still needs to be improved and enhanced. Summary of the invention

[0006] In view of the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a self-adhesive protective film, aiming to improve the high temperature resistance and tensile properties of the existing protective film, avoid breakage during high temperature molding, and residual adhesive when peeling.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A self-adhesive protective film comprises a self-adhesive layer, a core layer and an anti-adhesive back layer, wherein the self-adhesive layer is prepared from ethylene, propylene, 1-hexene copolymer and polypropylene, and the core layer and the anti-adhesive back layer are both prepared from block copolymer polypropylene.

[0009] In the self-adhesive protective film, the raw materials for preparing the self-adhesive layer include, by mass percentage: 80-95% of ethylene, propylene, 1-hexene copolymer and 5-20% of polypropylene.

[0010] In the self-adhesive protective film, in the self-adhesive layer, the polypropylene is homopolymer polypropylene.

[0011] In the self-adhesive protective film, the content of ethylene in the block copolymer polypropylene used to prepare the core layer is 8-25wt%.

[0012] In the self-adhesive protective film, the block copolymer polypropylene used to prepare the anti-adhesive backing layer has an ethylene content of 15-25wt%.

[0013] In the self-adhesive protective film, the surface roughness of the anti-adhesive backing layer is 0.1-0.4 μm.

[0014] In the self-adhesive protective film, the thickness ratio of the self-adhesive layer, the core layer and the anti-adhesive backing layer is (1-2.5): (5-8): (1-2.5).

[0015] Beneficial effects:

[0016] The present invention provides a self-adhesive protective film, which uses a blend of ethylene, propylene, 1-hexene copolymer and polypropylene as a self-adhesive layer, and uses polypropylene to change the amount of amorphous regions formed by ethylene, propylene and 1-hexene copolymer and the high temperature resistance, so that the self-adhesive layer has good viscosity at room temperature, can adhere to the surface of PC and PMMA plates, but does not melt and penetrate during the high temperature molding process, and its adhesive force does not increase, and then when peeled off, no residual glue will appear; at the same time, the core layer and the anti-adhesive back layer are made of block copolymer polypropylene, have good high temperature resistance and tensile properties, and can meet the molding requirements of complex structures. More importantly, since no additives are added to the raw materials for preparing the self-adhesive layer, the core layer and the anti-adhesive back layer, no components are precipitated during the high temperature molding process, and the product will not be contaminated. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of the self-adhesive protective film provided by the present invention.

[0018] Markings in the accompanying drawings: 1-self-adhesive layer, 2-core layer, 3-anti-adhesive backing layer. DETAILED DESCRIPTION

[0019] The present invention provides a self-adhesive protective film. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] Aiming at the defects that the existing protective film is easy to bubble and break after high temperature molding, and easy to leave residual adhesive when peeling, the present invention provides a self-adhesive protective film, such as Figure 1 As shown, the protective film includes a self-adhesive layer 1, a core layer 2, and an anti-sticking back layer 3 from top to bottom, wherein the self-adhesive layer is prepared from a blend of ethylene, propylene, 1-hexene copolymer and polypropylene, and the ethylene, propylene, 1-hexene copolymer in the self-adhesive layer can form an amorphous region structure, which has self-adhesiveness to PC, PMMA and other smooth-surface sheets, and can be attached to the surface of the sheet to play a self-adhesive role; and the added polypropylene can improve the high temperature resistance of the self-adhesive layer to avoid bubbles or melting during high-temperature processing; furthermore, since the polarities of ethylene, propylene, 1-hexene copolymer and polypropylene are different from those of PC and PMMA and are not soluble in each other, and polypropylene can improve the high temperature resistance of ethylene, propylene, 1-hexene copolymer, the adhesion of the self-adhesive layer will not change during the high-temperature molding process, and the protective film can be easily peeled off after high-temperature molding, and no residual glue will be left after peeling, so that the surface of PC, PMMA and other sheets can maintain a high degree of cleanliness. In addition, in the self-adhesive protective film, the core layer and the anti-sticking back layer are both prepared from block copolymer polypropylene. Since the melting point of block copolymer polypropylene is greater than 160°C, it has good temperature resistance, which enables the protective film to not bubble or melt during high-temperature molding and maintain good tensile properties, thereby meeting the molding requirements of complex structures to better protect the sheet or finished product.

[0021] In this embodiment, by using a blend of ethylene, propylene, 1-hexene copolymer and polypropylene as the self-adhesive layer, and using polypropylene to change the amount of amorphous regions formed by ethylene, propylene, and 1-hexene copolymer and the high temperature resistance, the self-adhesive layer has good viscosity at room temperature and can adhere to the surface of PC and PMMA sheets, but does not melt and penetrate during the high temperature molding process, and its adhesive force does not increase, and no residual glue will appear when peeled off; at the same time, the core layer and the anti-adhesive backing layer are made of block copolymer polypropylene, which have good high temperature resistance and tensile properties and can meet the molding requirements of complex structures. More importantly, since no additives are added to the raw materials for preparing the self-adhesive layer, the core layer and the anti-adhesive backing layer, no components are precipitated during the high temperature molding process, and the product will not be contaminated.

[0022] Since the addition of polypropylene in the self-adhesive layer will affect the formation of amorphous regions of ethylene, propylene, and 1-hexene copolymers, adding an appropriate amount of polypropylene can make ethylene, propylene, and 1-hexene copolymers form more amorphous regions to make the self-adhesive properties better. At the same time, the crystals formed by polypropylene can make the peeling performance of the self-adhesive film better and prevent the residual adhesive on the surface of the plate or finished product; however, when the content of polypropylene is too high, the crystallinity of polypropylene will be high, which will reduce the adhesion of the self-adhesive layer and cannot meet the actual use needs. In this regard, in a preferred embodiment, the raw materials for preparing the self-adhesive layer include, by mass percentage: 80-95% of ethylene, propylene, and 1-hexene copolymers and 5-20% of polypropylene. The blend of this ratio can make the self-adhesive layer have better adhesion and good high temperature resistance.

[0023] In a preferred embodiment, in the self-adhesive layer, the polypropylene is homopolymer polypropylene, which has good mechanical strength and heat resistance, can make the self-adhesive layer more resistant to high temperatures, avoid damage to the protective film during high-temperature molding, and can better play a protective role.

[0024] Since the core layer is the main layered structure that provides mechanical strength for the protective film, the use of block copolymer polypropylene can greatly improve the tensile properties of the protective film and meet the processing requirements of the special-shaped molding structure. Since the ethylene content in the block copolymer polypropylene will affect the thermal stability and tensile properties of the core layer, generally speaking, when the ethylene content is high, although the flexibility of the core layer is better, its thermal stability will decrease, especially when the ethylene content is higher than 25%, the heat resistance of the block copolymer polypropylene decreases, affecting the high temperature performance of the protective film. In this regard, in a preferred embodiment, the ethylene content in the block copolymer polypropylene used to prepare the core layer is 8 to 25wt%. The block copolymer polypropylene with this ethylene content has good high temperature resistance and good tensile properties, which can prevent the protective film from being damaged during high temperature molding.

[0025] In the specific use process, the anti-sticking backing layer is located on the outer surface, which is not only required to have good high temperature resistance and stretchability, but also to have anti-sticking properties, so that the protective film has good unwinding properties and cleanliness. For this, the present application uses block copolymer polypropylene as raw material, and adjusts the ethylene content in the block copolymer polypropylene to make its surface rough. In a preferred embodiment, the block copolymer polypropylene used to prepare the anti-sticking backing layer has an ethylene content of 15-25wt%. The block copolymer polypropylene of this ratio can form large-particle crystals on the surface, thereby changing the surface roughness to 0.1-0.4μm. The anti-sticking backing layer with such roughness has good unwinding performance, and does not stick to dust during use, which can keep the protective film clean. When the ethylene content is less than 15%, the surface of the block copolymer polypropylene is smooth, and its surface roughness is less than 0.1um. Because the roughness is too small, the adhesive layer of the protective film is easy to adhere to the back layer, and the unwinding effect is not good. When the ethylene content is greater than 25, the surface roughness of the block copolymer polypropylene is greater than 0.4um, and its back layer is too rough. Bubble marks are easily generated when the protective film is rolled up, which makes it easy for the adhesive layer to be rolled into bubbles when the film is pasted, causing bubbles and ridges after high temperature.

[0026] In a preferred embodiment, the thickness of the self-adhesive protective film is 30-50 μm. The self-adhesive film of this thickness can meet most high-temperature molding processes and can better protect PC, PMMA sheets or finished products.

[0027] In a more preferred embodiment, the thickness ratio of the self-adhesive layer, the core layer and the anti-sticking back layer is (1-2.5):(5-8):(1-2.5). The self-adhesive protective film with this thickness ratio has suitable adhesion, excellent tensile properties and high temperature resistance.

[0028] The aforementioned self-adhesive protective film is prepared by co-extrusion molding, and the specific preparation steps are as follows: after the raw materials are dusted, the raw materials for each layer are taken according to the formula, and after the raw materials for each layer are mixed evenly, they are melted by three single-screw extruders respectively, the melt is filtered, and then extruded through a co-extrusion die to cool into a film, and then cooled and formed, thickness detection, online defect detection, online slitting, winding and packaging are performed to obtain the final product.

[0029] It should be noted that, since the self-adhesive protective film is a high-cleanliness film, the production area from the die head to the winding area is a Class 1000 clean workshop.

[0030] To further illustrate the self-adhesive protective film provided by the present invention, the following embodiments are provided.

[0031] Example 1

[0032] A self-adhesive protective film has a thickness of 40 μm and is composed of a self-adhesive layer, a core layer and an anti-adhesive back layer with a thickness ratio of 1.5:7:1.5, wherein the self-adhesive layer is prepared from 90% by mass of ethylene, propylene, 1-hexene copolymer and 10% by mass of polypropylene, the core layer is prepared from block copolymer polypropylene with an ethylene content of 12 wt%, the anti-adhesive back layer is prepared from block copolymer polypropylene with an ethylene content of 20 wt%, and the surface roughness of the anti-adhesive back layer is 0.3 μm.

[0033] Example 2

[0034] A self-adhesive protective film has a thickness of 40 μm and is composed of a self-adhesive layer, a core layer and an anti-adhesive back layer with a thickness ratio of 1:8:1, wherein the self-adhesive layer is prepared from 80% by mass of ethylene, propylene, 1-hexene copolymer and 20% by mass of polypropylene, the core layer is prepared from block copolymer polypropylene with an ethylene content of 25wt%, the anti-adhesive back layer is prepared from block copolymer polypropylene with an ethylene content of 15wt%, and the surface roughness of the anti-adhesive back layer is 0.1 μm.

[0035] Example 3

[0036] A self-adhesive protective film has a thickness of 40 μm and is composed of a self-adhesive layer, a core layer and an anti-adhesive back layer with a thickness ratio of 2.5:5:2.5, wherein the self-adhesive layer is prepared from 95% by mass of ethylene, propylene, 1-hexene copolymer and 5% by mass of polypropylene, the core layer is prepared from block copolymer polypropylene with an ethylene content of 8wt%, the anti-adhesive back layer is prepared from block copolymer polypropylene with an ethylene content of 25wt%, and the surface roughness of the anti-adhesive back layer is 0.4 μm.

[0037] Comparative Example 1

[0038] The protective film prepared in Example 1 of the Chinese invention patent publication number CN115491146B is used as Comparative Example 1.

[0039] Comparative Example 2

[0040] A protective film is basically the same as Example 1, except that the raw material for preparing the self-adhesive layer is a copolymer of ethylene, propylene and 1-hexene.

[0041] Comparative Example 3

[0042] A protective film is substantially the same as that of Example 1, except that the self-adhesive layer is prepared from 50% by mass of a copolymer of ethylene, propylene and 1-hexene and 50% by mass of polypropylene.

[0043] Comparative Example 4

[0044] A protective film is substantially the same as that of Example 1, except that the content of ethylene in the block copolymer polypropylene used to prepare the core layer is 30 wt%.

[0045] Comparative Example 5

[0046] A protective film is substantially the same as that of Example 1, except that the content of ethylene in the block copolymer polypropylene used to prepare the anti-sticking backing layer is 30 wt%.

[0047] Performance Testing

[0048] High temperature resistance: Attach the prepared protective film to the surface of the PC sheet, place the sheet in an oven, heat it at 150°C for 30 minutes, and observe the state of the protective film; after cooling, observe whether there is residual glue on the PC surface under strong light in a dark and dust-free environment; install the end face of the sheet in a light guide in a dark and dust-free environment, and observe whether there is precipitate on the surface; heat it at 180°C for 10 minutes, and observe the state of the protective film.

[0049] Elongation: The transverse elongation and longitudinal elongation of the prepared protective film were tested according to GB / T 1040.3 standard, with a sample width of 15 mm and a stretching rate of 300 mm / min.

[0050] Adhesion: The prepared protective film was attached to the surface of the PC sheet, and the sheet was placed in an oven and heated at 150°C for 30 min and 180°C for 10 min. After cooling, the adhesion of the prepared protective film was tested according to GB / T 2792 standard. The bonding substrate was a PC sheet.

[0051] The test results are shown in Table 1.

[0052] Table 1. Performance test results

[0053]

[0054]

[0055] It can be seen from Table 1 that the protective films described in Examples 1-3 all have good high temperature resistance. During the test at 150°C and 180°C, no bubbles or tunnels will occur, there is no residual glue or precipitation on the surface, and the protective films are in good condition. At the same time, the elongation rates of Examples 1-3 are all high, and they have good tensile properties. The adhesion of the three will not change much after high-temperature heating, and they are easy to tear off when peeling without residual glue.

[0056] During the high temperature resistance test, although Comparative Example 1 did not produce bubbles and tunnels, it did have precipitation and partial melting. In addition, Comparative Example 1 had a higher adhesion and was easy to stick to the surface of the board when the protective film was peeled off.

[0057] In Comparative Example 2, since there is no polypropylene in the raw material of the self-adhesive layer, it is easy to form bubbles and tunnels under high temperature conditions, and its adhesion changes due to poor high temperature stability, making it more difficult to peel off.

[0058] In Comparative Example 3, due to the addition of a large amount of polypropylene, the adhesive force is insufficient and bubbles are easily generated. However, due to the high content of polypropylene, after being heated at 180° C., the polypropylene melts, which increases the adhesive force.

[0059] Comparative Example 4 can withstand a high temperature of 150°C, but at 180°C, bubbles and tunnels will appear. When the surface ethylene content is greater than 25, its high temperature resistance decreases, but its tensile properties are improved compared to Example 1.

[0060] Comparative Example 5 has a high ethylene content in the anti-adhesive backing layer and a rough surface, which leads to easy bubble marks when it is rolled up, and bubbles are easily drawn in when the film is pasted, causing bubbles and tunnels after high temperature, which reduces its high temperature resistance.

[0061] It can be seen that the self-adhesive protective film of the present invention can have good high temperature resistance, tensile properties and high temperature resistant adhesion, can meet the actual use needs of the sheet high temperature forming process, and has a better protective effect on the sheet.

[0062] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the claims attached to the present invention.

Claims

1. A self-adhesive protective film, comprising a self-adhesive layer, a core layer, and an anti-adhesive backing layer, characterized in that: The self-adhesive layer is prepared from ethylene, propylene, 1-hexene copolymer and polypropylene, and the core layer and the anti-adhesive back layer are both prepared from block copolymer polypropylene.

2. The self-adhesive protective film according to claim 1, characterized in that: Calculated by mass percentage, the raw materials for preparing the self-adhesive layer include: 80-95% of ethylene, propylene, 1-hexene copolymer and 5-20% of polypropylene.

3. The self-adhesive protective film according to claim 2, characterized in that: In the self-adhesive layer, the polypropylene is homopolymer polypropylene.

4. The self-adhesive protective film according to claim 1, characterized in that: The content of ethylene in the block copolymer polypropylene used to prepare the core layer is 8-25wt%.

5. The self-adhesive protective film according to claim 1, characterized in that: The content of ethylene in the block copolymer polypropylene used to prepare the anti-adhesive backing layer is 15-25wt%.

6. The self-adhesive protective film according to claim 5, characterized in that: The surface roughness of the anti-sticking backing layer is 0.1-0.4 μm.

7. The self-adhesive protective film according to claim 1, characterized in that: The thickness ratio of the self-adhesive layer, the core layer and the anti-adhesive backing layer is (1-2.5): (5-8): (1-2.5).

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