Polypropylene foam tape and preparation method thereof

Abstract

The invention discloses a polypropylene foam adhesive tape and a preparation method thereof, and belongs to the technical field of adhesive tape production. The polypropylene foam adhesive tape comprises polypropylene foam and an acrylate pressure-sensitive adhesive layer arranged on at least one side of the polypropylene foam, and a release layer is arranged on one side, deviating from the polypropylene foam, of the acrylate pressure-sensitive adhesive layer; wherein the polypropylene foam comprises a polypropylene copolymer foaming layer and a polypropylene film layer arranged on at least one side of the polypropylene copolymer foaming layer; wherein the polypropylene copolymer foaming layer comprises or consists of the following components in parts by weight: 80-98 parts of polypropylene copolymer; 2-20 parts by weight of a polyolefin copolymer; 3-10 parts by weight of a foaming agent; 0.8-3 parts by weight of an antioxidant; and 0.2 to 2.5 parts by weight of an auxiliary cross-linking agent. Compared with the prior art, the polypropylene foam tape is high in initial bonding strength, good in temperature resistance and easy to rework.

Description

Technical Field

[0001] The present invention relates to a polypropylene foam tape and a preparation method thereof, belonging to the technical field of tape production. Background Art

[0002] With the rapid development of automotive intelligence, in-vehicle display modules have become one of the important means for vehicle technological innovation and user experience improvement. In in-vehicle display modules, glue, double-sided polyethylene foam tape or acrylate foam tape is usually used to bond the panel and the protection frame. However, with the increasing number of display modules used in a single vehicle, the rework of display components and its efficiency have become important issues to be solved urgently.

[0003] The panel and the protection frame bonded with glue are difficult to disassemble during rework and repair, and are extremely prone to component damage, making it difficult to achieve reuse. When bonded with polyethylene foam tape or acrylate foam tape, although it can be disassembled, a large amount of foam and adhesive residue will remain on these components after disassembly. Removing these residues is time-consuming and laborious, and is likely to cause component damage and inability to be reused. In addition, the polyethylene foam tape has poor heat resistance and uneven surface, resulting in poor surface flatness of the adhesive layer after bonding, and it is difficult to meet the high requirements of in-vehicle display modules for initial bonding performance. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a polypropylene foam tape that is easy to rework and has good heat resistance, and a preparation method thereof.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention provides a polypropylene foam tape, comprising: a polypropylene foam and an acrylate pressure-sensitive adhesive layer provided on at least one side of the polypropylene foam, and a release layer is provided on the side of the acrylate pressure-sensitive adhesive layer away from the polypropylene foam; wherein, the polypropylene foam comprises a polypropylene copolymer foam layer and a polypropylene film layer provided on at least one side of the polypropylene copolymer foam layer; wherein, the polypropylene copolymer foam layer comprises or consists of the following components:

[0007] 80 - 98 parts by weight of polypropylene copolymer;

[0008] 2 - 20 parts by weight of polyolefin copolymer;

[0009] 3 - 10 parts by weight of foaming agent;

[0010] 0.8 - 3 parts by weight of antioxidant;

[0011] 0.2 - 2.5 parts by weight of auxiliary cross-linking agent.

[0012] Further, the thickness range of the polypropylene film layer is: 10um to 150um.

[0013] Further, the thickness range of the polypropylene copolymer foaming layer is: 300um to 1500um.

[0014] Further, the foaming ratio of the polypropylene copolymer foaming layer is: 5 to 15 times.

[0015] Further, the foaming agent is azodicarbonamide, the antioxidant is pentaerythritol ester, and the auxiliary crosslinking agent is triallyl trimellitate.

[0016] Further, the acrylate pressure-sensitive adhesive layer comprises 2-ethylhexyl acrylate, butyl acrylate, and acrylic acid.

[0017] Further, the release layer is a release film layer or a release paper layer.

[0018] The present invention further provides a method for preparing a polypropylene foam tape for preparing the above polypropylene foam tape, comprising the following steps:

[0019] S1: Preparation of polypropylene foam: Prepare a polypropylene copolymer foaming layer, and prepare a polypropylene film layer on at least one side of the polypropylene copolymer foaming layer;

[0020] S2: Preparation of acrylate pressure-sensitive adhesive: Add 2-ethylhexyl acrylate, butyl acrylate, acrylic acid, etc. into a reaction kettle, and add a polymerization initiator, and after heating and reacting, an acrylate copolymer solution is obtained; after adding a terpene resin modified with phenol and ethyl acetate and stirring sufficiently in the acrylate copolymer solution, an isocyanate crosslinking agent is added and stirred to obtain an acrylate pressure-sensitive adhesive;

[0021] S3: Preparation of polypropylene foam tape: Coat the acrylate pressure-sensitive adhesive prepared in step S2 on the release layer, and dry it at 90°C to completely volatilize the solvent, control the thickness of the pressure-sensitive adhesive layer to be 10um to 150um, then perform double-sided corona treatment on the polypropylene foam, and bond the dried acrylate pressure-sensitive adhesive layer on at least one side of the polypropylene foam.

[0022] Further, the preparation of the polypropylene foam comprises the following steps:

[0023] Melt-blend a polypropylene copolymer resin and a polyolefin copolymer, and add a foaming agent, an antioxidant, and an auxiliary crosslinking agent, and then melt-knead again to obtain a polypropylene copolymer to-be-foamed mixture;

[0024] Melt the polypropylene film resin to obtain a polypropylene mixture;

[0025] The polypropylene copolymer foamable mixture and the polypropylene mixture are co-extruded, roll-bonded, and cooled to form a sheet structure;

[0026] The sheet structure is placed in an electron accelerator for radiation cross-linking, and the cross-linked sheet structure is placed in a foaming device for high-temperature foaming to obtain the polypropylene foam.

[0027] Further, the preparation of the polypropylene foam includes the following steps:

[0028] The polypropylene copolymer resin and the polyolefin copolymer are melt-blended, and a foaming agent, an antioxidant, and an auxiliary cross-linking agent are added and then melt-kneaded again to obtain a polypropylene copolymer foamable sheet;

[0029] The sheet is placed in an electron accelerator for radiation cross-linking, and the cross-linked sheet is placed in a foaming device for high-temperature foaming to obtain a polypropylene copolymer foam;

[0030] The polypropylene film is melted with resin and laminated onto at least one surface of the polypropylene copolymer foam; after cooling, the polypropylene foam is obtained.

[0031] The beneficial technical effects of the present invention are:

[0032] The present invention provides a polypropylene foam tape and a preparation method thereof. By improving the composition of the polypropylene foam, especially by defining the ratio of the polypropylene copolymer to the polyolefin copolymer in the polypropylene copolymer foam layer, and providing a polypropylene film layer on at least one side of the polypropylene copolymer foam layer, the polypropylene foam tape of the present invention has excellent heat resistance. The surface of the polypropylene foam is smooth and flat, and thus, after being bonded to the pressure-sensitive adhesive layer, the surface is smooth and flat, resulting in excellent initial adhesion performance, enabling rapid bonding between components of the in-vehicle display module without falling off. At the same time, when the in-vehicle display module needs to be repaired, it can be quickly disassembled, and the residual foam and adhesive on the components can be easily removed. Description of the Drawings

[0033] Figure 1 is a schematic structural diagram of a polypropylene foam tape according to a preferred embodiment of the present invention. Detailed Description of the Embodiments

[0034] In order to better understand the technical means of the present invention and implement it according to the content of the specification, the following further describes the specific embodiments of the present invention in detail with reference to the drawings and embodiments. The following embodiments are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0035] Please refer to Figure 1 As shown, the present invention provides a polypropylene foam tape 100 with good heat resistance and easy reworkability.

[0036] The polypropylene foam tape 100 includes: a polypropylene foam 1 and an acrylate pressure-sensitive adhesive layer 2 provided on at least one side of the polypropylene foam 1. A release layer 3 is provided on the side of the acrylate pressure-sensitive adhesive layer 2 facing away from the polypropylene foam 1.

[0037] As Figure 1 shown, the polypropylene foam 1 is disposed in the middle, and acrylate pressure-sensitive adhesive layers 2 are provided on both the upper and lower sides of the polypropylene foam 1. A release layer 3 is provided on the side of one of the acrylate pressure-sensitive adhesive layers 2 facing away from the polypropylene foam 1. Of course, in other embodiments, release layers 3 can also be provided on the sides of both acrylate pressure-sensitive adhesive layers 2 facing away from the polypropylene foam 1. Alternatively, an acrylate pressure-sensitive adhesive layer 2 is provided on one side of the polypropylene foam 1, and a release layer 3 is provided on the side of the acrylate pressure-sensitive adhesive layer 2 facing away from the polypropylene foam 1.

[0038] Furthermore, the thickness range of the polypropylene foam tape 100 is from 400 um to 1600 um. The preferred thickness is from 450 um to 1400 um, and the more preferred thickness is from 600 um to 1100 um. With such a setting, it can meet the requirements of different in-vehicle display modules for the thickness of the bonding material, while taking into account the balance between bonding strength and flexibility, making it have excellent bonding effects and mechanical properties.

[0039] Furthermore, the polypropylene foam 1 includes a polypropylene copolymer foam layer 11 and a polypropylene film layer 12 provided on at least one side of the polypropylene copolymer foam layer 11. As Figure 1 shown, the polypropylene foam 1 includes a polypropylene copolymer foam layer 11 and polypropylene film layers 12 provided on both the upper and lower sides of the polypropylene copolymer foam layer 11. Of course, in other embodiments, the polypropylene film layer 12 can also be provided only on one side of the polypropylene copolymer foam layer 11. By providing the polypropylene film layer 12, the purpose of rapid disassembly is achieved, thereby significantly improving the rework efficiency of the in-vehicle display module, reducing the risk of component damage, and ensuring that the residual foam and adhesive can be easily removed from the panel and the protective frame after disassembly, realizing the efficient reuse of components.

[0040] Among them, the polypropylene copolymer foaming layer 11 comprises or consists of the following components: 80-98 parts by weight of polypropylene copolymer; 2-20 parts by weight of polyolefin copolymer; 3-10 parts by weight of foaming agent; 0.8-3 parts by weight of antioxidant; 0.2-2.5 parts by weight of auxiliary crosslinking agent. Preferably, 80-95 parts by weight of polypropylene copolymer; 5-20 parts by weight of polyolefin copolymer. By optimizing the proportion of each component in the polypropylene copolymer foaming layer 11, the polypropylene foam tape 100 has excellent temperature resistance. Under the condition of 125 °C, the dimensional change rate is less than 5%, showing excellent temperature stability and meeting the use requirements of the in-vehicle display module in a high-temperature environment. Moreover, the surface of the polypropylene foam 1 is flat, and there is no unevenness in the pressure-sensitive adhesive layer after fitting, improving the initial bonding strength effect and further enhancing the overall performance of the module. By precisely controlling the proportion of each component, the balance between the foaming ratio and temperature resistance is achieved, while ensuring the mechanical properties and processing properties of the foam, providing a stable process basis for industrial production.

[0041] Furthermore, the thickness range of the polypropylene copolymer foaming layer 11 is: 300um to 1500um. This thickness range ensures that while meeting the bonding strength requirements of the in-vehicle display module, the foam layer has sufficient flexibility and cushioning performance, and can effectively absorb external impact forces, protecting the panel and the protective frame from damage.

[0042] Furthermore, the foaming ratio of the polypropylene copolymer foaming layer 11 is: 5 to 15 times. Preferably, the foaming ratio is 8 to 12 times, and most preferably, the foaming ratio is 10 times. By precisely controlling the foaming ratio, it is ensured that the polypropylene copolymer foaming layer 11 has excellent bonding performance while maintaining light weight. When the foaming ratio is 8 to 12 times, the pore structure of the foam is uniform, and it can better combine with the acrylate pressure-sensitive adhesive layer 2, thereby improving the bonding strength of the overall double-sided tape. At a foaming ratio of 10 times, the temperature resistance of the foam layer reaches the best balance. Even in a high-temperature environment, the dimensional change rate can still be controlled at a very low level, ensuring the long-term stability of the in-vehicle display module under extreme conditions. The moderate foaming ratio not only reduces the weight of the foam layer but also enhances its cushioning performance, and can effectively absorb external impact forces, protecting the in-vehicle display module from vibration and collision.

[0043] The present invention realizes the rapid disassembly function of the polypropylene foam tape 100 by setting the polypropylene film layer 12, which is easy for rework. However, the thickness range of the polypropylene film layer 12 has a significant impact on the disassembly performance. When the polypropylene film layer 12 is relatively thin (such as less than 15um), it is prone to breakage during removal, resulting in the adhesive layer not being able to be smoothly removed together with the film layer, thus increasing the disassembly difficulty. On the contrary, when the thickness range of the polypropylene film layer 12 is: 10um to 150um. Preferably, the thickness range of the polypropylene film layer 12 is from 15um to 100um, and more preferably, when the thickness range of the polypropylene film layer 12 is 50um, its mechanical properties and flexibility reach the best balance. During the stretching process, the polypropylene film layer 12 can effectively reduce the viscosity of the adhesive, making it easier to separate from the surface of the panel or the protective frame, thereby realizing rapid disassembly. In addition, the moderate thickness ensures the flatness of the polypropylene film layer 12, enabling the adhesive layer to be evenly adhered, and enhancing the initial bonding strength effect. Moreover, the 50um film layer thickness shows excellent performance in heat resistance and mechanical strength, and can meet the usage requirements of in-vehicle display modules under high temperature and mechanical shock.

[0044] Further, the thickness range of the polypropylene film layer 12 is: 10um to 150um. Preferably, the thickness range of the polypropylene film layer 12 is from 15um to 100um, and more preferably, the thickness range of the polypropylene film layer 12 is 50um.

[0045] Further, the blowing agent used in the present invention is azodicarbonamide, the antioxidant is pentaerythritol ester, and the auxiliary cross-linking agent is triallyl trimellitate. Of course, in other embodiments, other blowing agents, antioxidants, and auxiliary cross-linking agents can also be used, and the present invention is not limited thereto.

[0046] Further, by setting the acrylate pressure-sensitive adhesive layer 2, the rapid bonding effect is realized. The acrylate pressure-sensitive adhesive layer 2 includes 2-ethylhexyl acrylate, butyl acrylate, and acrylic acid. Of course, other required monomers can also be included, such as 2-hydroxyethyl acrylate, etc., and the acrylate pressure-sensitive adhesive is prepared by a polymerization reaction through a process.

[0047] Further, the release layer 3 is a release film layer or a release paper layer. Such a setting provides excellent release performance, mechanical properties, and chemical resistance for the polypropylene foam tape 100, meeting the requirements of different application scenarios.

[0048] The present invention also provides a preparation method of the polypropylene foam tape 100 for preparing the above-mentioned polypropylene foam tape 100, including the following steps:

[0049] S1: Preparation of polypropylene foam 1: Prepare a polypropylene copolymer foam layer 11, and prepare a polypropylene film layer 12 on at least one side of the polypropylene copolymer foam layer 11;

[0050] S2: Preparation of acrylate pressure-sensitive adhesive: Add 2-ethylhexyl acrylate, butyl acrylate, acrylic acid, etc. into a reaction kettle, add a polymerization initiator, and obtain an acrylate copolymer solution after heating and reacting; add a terpene resin modified with phenol and ethyl acetate to the acrylate copolymer solution, stir well, and then add an isocyanate cross-linking agent and stir to obtain the acrylate pressure-sensitive adhesive;

[0051] S3: Preparation of polypropylene foam tape 100: Coat the acrylate pressure-sensitive adhesive prepared in step S2 on the release layer 3, and dry it at 90°C to completely volatilize the solvent, control the thickness of the pressure-sensitive adhesive layer to be 10 um to 150 um, then corona-treat both sides of the polypropylene foam 1, and bond the dried acrylate pressure-sensitive adhesive layer on at least one side of the polypropylene foam 1.

[0052] In some embodiments, the preparation of the polypropylene foam 1 includes the following steps:

[0053] Melt-blend a polypropylene copolymer resin and a polyolefin copolymer, add a foaming agent, an antioxidant, and an auxiliary cross-linking agent, and then melt-mix again to obtain a polypropylene copolymer to-be-foamed mixture;

[0054] Melt a polypropylene film with resin to obtain a polypropylene mixture;

[0055] Co-extrude the polypropylene copolymer to-be-foamed mixture and the polypropylene mixture, and after roll compaction and cooling, form a sheet structure;

[0056] Place the sheet structure in an electron accelerator for irradiation cross-linking, and place the cross-linked sheet structure in a foaming device for high-temperature foaming to obtain the polypropylene foam 1.

[0057] That is, in this embodiment, the polypropylene copolymer to-be-foamed mixture and the polypropylene mixture are co-extruded and cooled, and then subjected to high-temperature foaming together to obtain the polypropylene foam 1. By blending the polypropylene copolymer and the polyolefin copolymer, the crystallization and melting behaviors of the material can be significantly improved, and its mechanical properties and aging resistance can be enhanced. Through the processes of co-extrusion and high-temperature foaming, a uniform cell structure can be obtained, further optimizing the mechanical properties, heat resistance, and rapid disassembly performance of the foam. This process flow can improve the processing performance of the material and make it more suitable for large-scale industrial production.

[0058] In other embodiments, the preparation of the polypropylene foam 1 includes the following steps:

[0059] Melt-blend a polypropylene copolymer resin and a polyolefin copolymer, add a foaming agent, an antioxidant, and an auxiliary cross-linking agent, and then melt-mix again to obtain a polypropylene copolymer to-be-foamed sheet;

[0060] Place the sheet in an electron accelerator for irradiation cross-linking, and place the cross-linked sheet in a foaming device for high-temperature foaming to obtain a polypropylene copolymer foam;

[0061] Melt the polypropylene film with resin and cast it onto at least one surface of the polypropylene copolymer foam; after cooling, obtain the polypropylene foam 1.

[0062] That is, in this embodiment, first obtain the polypropylene copolymer foam layer 11, and then cast a polypropylene mixture onto at least one side of the polypropylene copolymer foam. Specifically, melt the polypropylene film with resin in an extruder, then cast it onto one side of the polypropylene copolymer foam layer 11 and control the thickness, and then cool it through a cooling roll. Then, use the same method to cast the polypropylene film layer 12 onto the other side of the polypropylene copolymer foam layer 11. With such a setting, on the premise of realizing rapid disassembly, the surface flatness and smoothness of the foam can be significantly improved, making it more suitable for application scenarios with higher surface quality requirements, such as in-vehicle display modules. The cast film layer provides a better bonding substrate for the foam, and can form a more firm bond with the acrylate pressure-sensitive adhesive layer 2, thereby enhancing the overall bonding strength and reliability of the double-sided tape. The casting process forms a uniform protective layer on the surface of the foam, enhancing the impact resistance and wear resistance of the foam while maintaining the lightweight characteristics of the foam.

[0063] For the sake of clear description, the following description in the specification will be detailed with specific embodiments, but should not be limited thereto.

[0064] Example 1

[0065] (1) Preparation of polypropylene foam 1

[0066] Melt and blend 95 parts of polypropylene copolymer resin (density 0.90 g / cm3, melt index MFR 3.5 g / 10 minutes) and 5 parts of polyolefin copolymer in an extruder, and add 7 parts of blowing agent azodicarbonamide, 2 parts of antioxidant Irganox1010, and 2.3 parts of auxiliary cross-linking agent triallyl trimellitate, and further carry out melt mixing at 170 °C. At the same time, melt the polypropylene film resin (density 0.92 g / cm3, melt index MFR 8.0 g / 10 minutes) in another 2 extruders at 170 °C. Then, extrude the molten materials in the above three extruders through a three-layer co-extrusion die head, and make a sheet with a three-layer structure through roll compaction, cooling, etc. The structure is a three-layer structure of polypropylene film layer 12, polypropylene copolymer to-be-foamed layer, and polypropylene film layer 12. Among them, the thickness of the polypropylene film layer is controlled to be 50 μm.

[0067] Place the above sheet in a 2.0 MeV electron accelerator for irradiation crosslinking with an irradiation dose of 100 kGy. Place the crosslinked sheet in a foaming device for foaming at a high temperature of 250 °C to obtain the polypropylene foam 1.

[0068] (2) Preparation of acrylate pressure-sensitive adhesive

[0069] Add 15 parts by weight of 2-ethylhexyl acrylate, 55 parts by weight of butyl acrylate, 23.5 parts by weight of methyl acrylate, 6.5 parts by weight of acrylic acid, 0.3 parts by weight of 2-hydroxyethyl acrylate, and 100 parts by weight of ethyl acetate into a reaction kettle, and introduce nitrogen for 20 minutes to remove air. Add 0.09 parts by weight of polymerization initiator azobisisobutyronitrile to the monomer and solvent mixture, heat up to 65 °C and react for 8 hours to obtain an acrylate copolymer solution. The weight-average molecular weight of the acrylic copolymer is 800,000, and the Tg is -36 °C. Add 5 parts by weight of terpene resin modified with phenol with a softening point of 147 °C and 50 parts by weight of ethyl acetate to every 100 parts by weight of the above blend solution and stir well, then add 0.09 parts by weight of Covestro isocyanate crosslinking agent L-75 and stir to obtain an acrylate pressure-sensitive adhesive.

[0070] (3) Preparation of polypropylene foam tape 100

[0071] Coat the acrylate pressure-sensitive adhesive prepared in step (2) on the release layer 3, dry at 90 °C to completely volatilize the solvent, and control the thickness of the pressure-sensitive adhesive layer to be 50 μm. Then respectively bond the completely dried acrylate pressure-sensitive adhesive layer to both sides of the double-sided corona-treated polypropylene foam 1, and remove the release layer on one side. Obtain the target double-sided tape.

[0072] Example 2

[0073] Except that the resin in the polypropylene copolymer foam layer 11 in Example 1 is changed to 85 parts of polypropylene copolymer resin and 15 parts of polyolefin copolymer, and the thickness of the polypropylene film layer during extrusion of the sheet is changed to 30 μm, the polypropylene foam tape 100 is obtained in the same manner as in Example 1.

[0074] Example 3

[0075] Except that one side of the polypropylene copolymer foam layer 11 is extruded with a polypropylene film layer 12 when preparing the sheet to be foamed, the polypropylene foam tape 100 is obtained in the same manner as in Example 1.

[0076] Example 4

[0077] Except that the blowing agent azodicarbonamide is changed to 4.5 parts, the polypropylene foam tape 100 is obtained in the same manner as in Example 1.

[0078] Comparative Example 1

[0079] Change the resin component in the polypropylene copolymer foaming layer 11 to 70 parts of polypropylene copolymer resin and 30 parts of polyolefin copolymer, and foam in the same manner as in Example 1 to obtain a foam only with the polypropylene copolymer foaming layer 11. Then, bond the adhesive prepared in Example 1 to the foam only with the polypropylene copolymer foaming layer 11 in the same manner to obtain the polypropylene foam tape 100.

[0080] Comparative Example 2

[0081] Prepare the polypropylene foam 1 in the same manner as in Example 1, change the polypropylene film layer 12 to 8um, and keep the others the same as in Example 1 to obtain the polypropylene foam tape 100.

[0082] Comparative Example 3

[0083] Corona treat a commercially available polypropylene foam 1 with a thickness of 1.0 mm, a foaming ratio of 12 times, and a tensile strength of 1.8 MPa, and bond the adhesive prepared in the same manner as in the example to both sides of the foam to obtain the polypropylene foam tape 100.

[0084] Test the properties such as peel strength, shear strength, and heat resistance of the polypropylene foam tapes 100 obtained in the above examples and comparative examples, and test the rework removal performance of the polypropylene foam tapes bonded and fixed between the PC / ABS alloy plate and the glass with an ink layer. The test results are shown in Table 1.

[0085] Table 1 Performance Test Results of Polypropylene Foam Tape

[0086]

[0087]

[0088] As can be seen from Table 1, Example 1 is the best example, which has high peel strength, excellent shear strength, and outstanding heat resistance and rework removal performance, and is suitable for high - requirement application scenarios. In Example 2, the ratio of polypropylene copolymer resin and polyolefin copolymer was modified, and the thickness of the polypropylene film was also modified. Although the peel strength and shear strength decreased slightly, the overall performance was still good. The heat resistance was slightly inferior to that of Example 1, but the rework removal performance was not affected. In Example 3, it was easy to remove with the polypropylene film layer 12, while it was difficult to remove on the side without the polypropylene film layer 12, indicating that the polypropylene film layer 12 played a role in rapid disassembly. In Example 4, reducing the amount of foaming agent decreased the foaming ratio, but the peel strength and rework removal performance were not affected. The heat resistance decreased slightly but was still within an acceptable range. This shows that the amount of foaming agent affects the foaming ratio and heat resistance, but has little effect on the peel strength and rework removal performance.

[0089] Comparing Comparative Example 1 with Example 1, it can be seen that the imbalance in the resin ratio leads to a significant decrease in the peel strength and shear strength, and the heat resistance and rework removability are also poor. This indicates that the resin ratio has a significant impact on the performance. The optimized ratio is 80% - 95% polypropylene copolymer resin and 5% - 20% polyolefin copolymer.

[0090] Comparing Comparative Example 2 with Example 1, it can be seen that when the polypropylene film layer 12 is too thin, it is easy to cause poor rework removability, indicating that the film layer thickness is crucial for the rework performance. The removal of the polypropylene foam tape 100 is mainly due to the stretching of the polypropylene film layer 12 during removal, which leads to a decrease in the viscosity of the adhesive layer and is removed together with the polypropylene film layer 12. When the polypropylene film layer 12 is relatively thin, the polypropylene film layer 12 is prone to breakage during removal and is difficult to remove. Therefore, the appropriate thickness range of the polypropylene film layer 12 is 10um to 150um, preferably 15um to 100um, and more preferably 50um.

[0091] Comparing Comparative Example 3 with Example 1, it can be seen that the performance of the commercially available foam is poor. The polypropylene foam 1 prepared by the present invention significantly improves the comprehensive performance of the polypropylene foam 1 through optimizing the formula, irradiation cross-linking technology and double-layer film structure design, especially in terms of heat resistance, initial adhesion strength performance and rework removability, which is significantly better than the commercially available foam.

[0092] Specifically, by using a specific ratio of polypropylene copolymer resin and polyolefin copolymer (such as 80% - 95% polypropylene copolymer resin and 5% - 20% polyolefin copolymer), combined with a foaming agent, an antioxidant and an auxiliary cross-linking agent, the comprehensive performance of the foam is optimized. Through irradiation cross-linking treatment with an electron accelerator, a stable three-dimensional network structure is formed. This process not only improves the mechanical strength and heat resistance of the foam, but also improves its dimensional stability. By providing a polypropylene film layer 12 (with a thickness range of 10um to 150um, preferably 50um) on both sides or one side of the polypropylene foam 1, the rework removability and surface flatness are significantly improved. This design makes the foam easier to remove from the substrate surface during rework and reduces the residual glue. By optimizing the dosage of the foaming agent and the process conditions, the foaming ratio is controlled within 5 to 15 times (preferably 8 to 12 times, most preferably 10 times), thereby achieving uniform foaming of the foam and excellent cushioning performance.

[0093] In summary, the present invention provides a polypropylene foam tape 100 and a preparation method thereof. By improving the composition of the polypropylene foam 1, especially by defining the ratio of the polypropylene copolymer to the polyolefin copolymer in the polypropylene copolymer foam layer 11, and providing a polypropylene film layer 12 on at least one side of the polypropylene copolymer foam layer 11, the polypropylene foam tape 100 of the present invention has excellent heat resistance. The surface of the polypropylene foam 1 is smooth and flat, and thus the surface is smooth and flat after being bonded to the pressure-sensitive adhesive layer, resulting in excellent initial adhesion performance, enabling rapid bonding between components of the in-vehicle display module without falling off. At the same time, when the in-vehicle display module needs to be repaired, it can be quickly disassembled, and the residual foam and adhesive on the components can be easily removed.

[0094] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A polypropylene foam tape, characterized in that: include: A polypropylene foam and an acrylate pressure-sensitive adhesive layer disposed on at least one side of the polypropylene foam, wherein a release layer is disposed on the side of the acrylate pressure-sensitive adhesive layer facing away from the polypropylene foam; wherein the polypropylene foam comprises a polypropylene copolymer foam layer and a polypropylene film layer disposed on at least one side of the polypropylene copolymer foam layer; wherein the polypropylene copolymer foam layer comprises or consists of the following components: Polypropylene copolymer 80-98 parts by weight; 2-20 parts by weight of polyolefin copolymer; 3-10 parts by weight of foaming agent; 0.8-3 parts by weight of antioxidant; Auxiliary cross-linking agent 0.2-2.5 parts by weight.

2. The polypropylene foam tape according to claim 1, characterized in that: The thickness of the polypropylene film layer ranges from 10um to 150um.

3. The polypropylene foam tape according to claim 1, characterized in that: The thickness of the polypropylene copolymer foaming layer ranges from 300um to 1500um.

4. The polypropylene foam tape according to claim 1, characterized in that: The foaming ratio of the polypropylene copolymer foaming layer is 5 to 15 times.

5. The polypropylene foam tape according to claim 1, characterized in that: The foaming agent is azodicarbonamide, the antioxidant is pentaerythritol ester, and the auxiliary cross-linking agent is triallyl benzene trimecyl.

6. The polypropylene foam tape according to claim 1, characterized in that: The acrylic ester pressure-sensitive adhesive layer comprises 2-ethylhexyl acrylate, butyl acrylate and acrylic acid.

7. The polypropylene foam tape according to claim 1, characterized in that: The release layer is a release film layer or a release paper layer.

8. A method for preparing a polypropylene foam tape, for preparing the polypropylene foam tape as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: S1: Preparation of polypropylene foam: preparing a polypropylene copolymer foaming layer, and preparing a polypropylene film layer on at least one side of the polypropylene copolymer foaming layer; S2: Preparation of acrylic pressure-sensitive adhesive: 2-ethylhexyl acrylate, butyl acrylate and acrylic acid are added into a reaction kettle, and a polymerization initiator is added, and an acrylic copolymer solution is obtained after heating. Phenol-modified terpene resin and ethyl acetate are added into the acrylic copolymer solution and stirred sufficiently, and then an isocyanate cross-linking agent is added and stirred to obtain an acrylic pressure-sensitive adhesive; S3: Preparation of polypropylene foam tape: Apply the acrylate pressure-sensitive adhesive prepared in step S2 on the release layer and dry it at 90°C to completely evaporate the solvent, control the thickness of the pressure-sensitive adhesive layer to be 10um to 150um, then corona treat the polypropylene foam on both sides, and adhere the dried acrylate pressure-sensitive adhesive layer to at least one side of the polypropylene foam.

9. The method for preparing the polypropylene foam tape according to claim 8, characterized in that: The polypropylene foam preparation comprises the following steps: The polypropylene copolymer resin and the polyolefin copolymer are melt-blended, and a foaming agent, an antioxidant and an auxiliary cross-linking agent are added and melt-kneaded again to obtain a polypropylene copolymer mixture to be foamed; melting the polypropylene film with the resin to obtain a polypropylene mixture; The polypropylene copolymer to-be-foamed mixture and the polypropylene mixture are co-extruded, rolled, and cooled to form a sheet structure; The sheet structure is placed in an electron accelerator for irradiation cross-linking, and the cross-linked sheet structure is placed in a foaming device for high-temperature foaming to obtain the polypropylene foam.

10. The method for preparing the polypropylene foam tape according to claim 8, characterized in that: The polypropylene foam preparation comprises the following steps: The polypropylene copolymer resin and the polyolefin copolymer are melt-blended, and a foaming agent, an antioxidant and an auxiliary cross-linking agent are added and melt-kneaded again to obtain a polypropylene copolymer sheet to be foamed; Placing the sheet in an electron accelerator for irradiation cross-linking, and placing the cross-linked sheet in a foaming device for high-temperature foaming to obtain a polypropylene copolymer foam; The polypropylene film resin is melted and then filmed on at least one surface of the polypropylene copolymer foam; and the polypropylene foam is obtained after cooling.

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