PVC wafer protective film and preparation method thereof

Abstract

The invention belongs to the technical field of semiconductor processing auxiliary materials, and particularly relates to a PVC wafer protection film and a preparation method thereof. By compounding the polyester plasticizer and the powder modifier, a double insurance mechanism of'source replacement + adsorption anchoring 'is formed, so that an adhesive layer is effectively guaranteed to be completely separated from a base material when the PVC wafer protective film is stripped, and residual adhesive is further prevented from remaining on the surface of a wafer. According to the invention, the TPU elastomer and the rigid powder modifier are introduced to form a'soft-hard 'synergistic enhancement system, so that the prepared PVC wafer protection film shows puncture resistance far beyond that of a conventional formula when being punctured. By designing a multi-stage precise plasticizing control system, the plasticizing degree of PVC is synergistically regulated and controlled, the problems of molecular chain degradation, material embrittlement, puncture deformation and reduction of elongation at break caused by excessive plasticizing are effectively avoided, and meanwhile, the phenomenon that TPU and an inorganic powder modifier are non-uniformly dispersed is avoided.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor processing auxiliary materials technology, and particularly relates to a PVC wafer protective film and its preparation method. Background Technology

[0002] In the semiconductor manufacturing industry, the wafer, as the core substrate carrying integrated circuits, directly determines the yield of the final product due to the flatness and cleanliness of its surface. During a series of downstream processes such as wafer dicing, grinding, transportation, and storage, its surface is highly susceptible to mechanical scratches, particulate contamination, or chemical corrosion. Therefore, a specialized protective film is typically applied to the wafer surface to provide physical and chemical barriers.

[0003] Currently, most wafer protective films on the market use polyvinyl chloride (PVC), polyethylene (PE), or polyolefin elastomer (POE) as the substrate and are coated with acrylic pressure-sensitive adhesives. However, these conventional protective films reveal two key technical challenges that urgently need to be addressed during use: 1. Residual adhesive issue To improve the flexibility and processability of the substrate, phthalate-based small-molecule plasticizers are often added during production. These plasticizers have small molecular weights and are thermally active. Under changes in ambient temperature or prolonged adhesion pressure, they migrate and diffuse from the substrate layer to the adhesive layer. After penetrating the adhesive layer, the plasticizer acts as a "deplasticizer" or "diluter," significantly reducing the cohesive strength and adhesion properties of the pressure-sensitive adhesive. This damages the interfacial adhesion between the substrate film and the adhesive layer, making the adhesion weaker than that between the adhesive layer and the wafer. Therefore, when the protective film is peeled off, the site of interfacial damage shifts from the "adhesive layer / wafer" interface to the "substrate / adhesive layer" interface, causing some adhesive to detach from the substrate and remain on the wafer surface. This residual adhesive is not only difficult to clean but can also cause pattern defects in subsequent photolithography, etching, and other processes, leading to product scrap.

[0004] 2. Insufficient puncture resistance: During wafer fabrication, wafers face localized stress impacts from sharp points, accidental tool knocks, or the introduction of hard particles. Traditional single-polymer substrates have limited toughness, resulting in insufficient tear and puncture resistance. When struck by a sharp object, the protective film is easily punctured, completely compromising its protective function and causing scratches or even cracks on the wafer surface, leading to irreversible economic losses. Puncture resistance can typically be improved by increasing the substrate thickness, but this sacrifices the film's flexibility and adhesion, and increases costs.

[0005] In summary, developing a wafer protective film that leaves no residue and has excellent puncture resistance has become an important technological development direction in the field of semiconductor packaging materials. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of existing technologies, such as the easy detachment of colloids from the substrate layer of wafer protective film, leaving residues on the wafer surface, making it difficult to clean the residues in subsequent processes, easily leading to product scrap, and insufficient puncture resistance of wafer protective films. The present invention provides a PVC wafer protective film and its preparation method.

[0007] To achieve the above-mentioned objectives, the present invention is implemented through the following technical solution: A PVC wafer protective film, comprising the following components: PVC resin, polyester plasticizer, thermoplastic polyurethane elastomer (TPU), and powder modifier; The polyester plasticizer has a molecular weight of 1500-6000, the thermoplastic polyurethane elastomer is polyester-type TPU with a hardness of 85-95 A, and the powder modifier has a specific surface area greater than 150 m². 2 / g.

[0008] This invention selects high molecular weight polyester plasticizers with a molecular weight between 1500 and 6000, completely replacing traditional small molecule plasticizers. These polyester plasticizers, due to their longer molecular chains, exhibit stronger entanglement with PVC molecular chains, significantly inhibiting migration activity. This greatly reduces the driving force and likelihood of plasticizer molecules migrating from the substrate to the adhesive layer, fundamentally stabilizing the interface between the substrate and the adhesive layer. Furthermore, because the powder modifier has an extremely high specific surface area and abundant pore structure, its dispersion in the substrate can effectively adsorb and fix any trace amounts of migrating plasticizer molecules that may exist in the formulation, thereby preventing them from reaching the interface region and forming a second, robust line of defense. Therefore, this invention introduces a specific surface area greater than 150 m². 2 / g of powder modifier. This invention, through the combined action mechanism of "high molecular weight polyester plasticizer + high adsorption powder modifier", ensures that the adhesion force between the adhesive layer and the film is always stably greater than the adhesion force between the adhesive layer and the substrate throughout the entire service life of the PVC wafer protective film. This effectively ensures that the adhesive layer completely detaches from the substrate when peeling off the PVC wafer protective film, thereby fundamentally preventing residual adhesive from remaining on the wafer surface.

[0009] Furthermore, this invention constructs a unique synergistic reinforcement system combining both hard and soft materials. TPU itself is a material with high elasticity, high strength, and excellent wear resistance. TPU within the hardness range of 85-95 A exhibits good compatibility with the PVC matrix and can be uniformly dispersed in a microscopic "island structure." When the PVC wafer protective film is impacted by a sharp object, the TPU elastomer particles can effectively absorb and disperse impact energy through significant plastic deformation, delaying crack initiation and propagation, thus acting as an "energy absorber." Simultaneously, the high specific surface area powder modifier, acting as rigid particles, is uniformly dispersed in the PVC / TPU matrix, providing pinning and reinforcement, helping to improve the overall modulus and strength of the matrix, and effectively resisting the intrusion of penetrating objects. More importantly, during stress, these rigid particles can induce a large number of crazing and shear bands, further dissipating impact energy. The synergistic effect of the "soft" toughness of TPU and the "hard" reinforcement of powder modifiers enables the PVC wafer protective film to not only buffer stress through deformation when subjected to local sharp stress, but also resist penetration with the reinforced matrix, thereby achieving a significant improvement in puncture resistance.

[0010] Preferably, a PVC wafer protective film comprises the following components by weight: 100 parts PVC resin, 30-60 parts polyester plasticizer, 60-140 parts thermoplastic polyurethane elastomer (TPU), and 3-10 parts powder modifier.

[0011] As a preferred embodiment, a PVC wafer protective film, by weight, further comprises: Stabilizer 4-8 parts, impact modifier 5-15 parts, processing aid 1-3 parts, antioxidant 0.2-1 parts.

[0012] As a preferred embodiment, a PVC wafer protective film further includes 0.2 to 1 part by weight of colorant.

[0013] Preferably, a PVC wafer protective film comprises, by weight parts: 100 parts PVC resin, 44 parts polyester plasticizer, 100 parts thermoplastic polyurethane elastomer (TPU), 5 parts powder modifier, 5.5 parts stabilizer, 8 parts impact modifier, 1.5 parts processing aid, 0.5 parts antioxidant, and 0.5 parts colorant.

[0014] Preferably, the polyester plasticizer is adipic acid polyester.

[0015] Preferably, the powder modifier is any one or a combination of fumed silica, zeolite, and hydrotalcite.

[0016] Preferably, the degree of polymerization of the PVC resin is 1300~1800.

[0017] Preferably, the stabilizer is a barium-zinc stabilizer; The impact modifier is a core-shell structured acrylate impact modifier; The processing aid is PA-40; The antioxidant is any one or a combination of antioxidant 1010, antioxidant 1035, and antioxidant 1135.

[0018] As a further preferred option, the stabilizer is any one or a combination of ADK AC-255E, UBZ 293 TR, and UBZ 6301.

[0019] As a further preferred embodiment, the impact modifier is any one or a combination of MBS resin, ACR resin, and CPE resin.

[0020] As a further preferred option, the impact modifier is MBS resin.

[0021] Preferably, the pigment is any one or a combination of β-stable phthalocyanine blue pigment, 2,9-dimethylquinacridone, and α-unstable phthalocyanine blue pigment.

[0022] A method for preparing a PVC wafer protective film as described above includes the following steps: S1: Dry the thermoplastic polyurethane elastomer (TPU); S2: Weigh the raw materials according to the PVC wafer protective film formula, mix and stir, and cool to room temperature to obtain the premix; S3: The premix obtained in step S2 is subjected to plasticization in an internal mixer, secondary plasticization in a two-roll mill, and filtration in sequence to obtain compressed material; The plasticizing temperature of the internal mixer is 175~185 ℃, and the secondary plasticizing temperature of the two-roll open mill is 155~165 ℃. S4: The pressed material obtained in step S3 is calendered into a film using a five-roll calender, and then embossed. The temperature control of each roll during the calendering process is as follows: The temperature of the first roller is 155~165 ℃, the temperature of the second roller is 160~170 ℃, the temperature of the third roller is 163~173 ℃, the temperature of the fourth roller is 162~172 ℃, and the temperature of the fifth roller is 160~170 ℃. S5: Cool, trim, and roll up to obtain a PVC wafer protective film.

[0023] For multi-component blends like PVC / TPU / inorganic powders, where compatibility requires precise control, insufficient plasticization means that PVC resin particles fail to melt fully, high-molecular-weight plasticizers cannot adequately insert into the PVC molecular chains to exert their plasticizing effect, and TPU particles and inorganic powders cannot be uniformly dispersed in the PVC matrix. This results in unmelted PVC particles or microscopic voids within the material. This further leads to poor mechanical properties (such as tensile strength and elongation at break) and poor puncture resistance. More importantly, plasticizer molecules that have not formed a stable bond with the PVC molecular chains have higher migration freedom and will slowly precipitate to the surface, leaving residual adhesive. Conversely, excessive plasticization can cause PVC molecular chains to break and degrade due to excessive thermomechanical stress. TPU may also partially crosslink or deteriorate due to overheating, causing the material to become brittle, with a significant decrease in puncture deformation and toughness.

[0024] This invention designs a multi-stage plasticizing and molding system with precisely coordinated temperature parameters. By controlling the plasticizing temperature of the internal mixer and the secondary plasticizing temperature of the two-roll mill, it promotes the uniform dispersion of TPU and powder modifiers in the PVC matrix, while effectively avoiding overheating degradation caused by continuous high temperatures. Simultaneously, this invention ensures that the material remains in an ideal viscoelastic state throughout the process of passing through the roll gap and stretching into a film by controlling the temperature of each roll of the five-roll calender. This is because if the temperature of each roll of the five-roll calender is too high, the film preform is prone to sticking to the rolls or developing defects due to degradation; if the temperature of each roll of the five-roll calender is too low, the extensibility is insufficient, internal stress increases, and thus affects the flatness and internal quality of the PVC wafer protective film. The PVC wafer protective film preparation process of this invention can avoid uneven component dispersion and interface defects caused by insufficient plasticization, and effectively prevent material degradation caused by over-plasticization.

[0025] As a preferred embodiment, the speed of each roll during the calendering process in step S4 is set as follows: The speed of the first roller is 3~10 m / min, the speed of the second roller is 13~21 m / min, the speed of the third roller is 20~28 m / min, the speed of the fourth roller is 25~33 m / min, and the speed of the fifth roller is 33~40 m / min.

[0026] Preferably, the drying temperature in step S1 is 80~100 ℃ and the drying time is 4~8 h.

[0027] TPU material itself is hygroscopic. If the moisture it contains vaporizes during subsequent high-temperature processing, it will not only form micro-bubbles or defects within the film, becoming stress concentration points and reducing puncture resistance, but also cause polymer hydrolysis and degradation due to the moisture, damaging the mechanical properties of the TPU itself and its interfacial bonding with the PVC matrix, indirectly affecting the integrity of the final PVC wafer protective film. Strict drying treatment provides a stable and dry raw material base for subsequent high-temperature plasticizing, effectively ensuring the uniformity and good performance of the final product.

[0028] Preferably, a filter is used in the filtration process in step S3, and the filter mesh size of the filter is 120~200 mesh.

[0029] Preferably, the overall rolling linear speed in step S4 is 5~40 m / min.

[0030] Preferably, in step S4, an embossing roller is used for embossing. The embossing roller is a medium-gloss roller with a temperature of 50~70 ℃ and an embossing pressure of 40~70 N.

[0031] Preferably, in step S4, the temperature of the rubber roller that is bonded to the embossing roller during the embossing process is 15~35 ℃, and the mesh size of the rubber roller is 400~700 mesh.

[0032] Preferably, in step S4, after calendering, the film is drawn out by the take-up roller and then embossed using the embossing roller; the stretch ratio between the take-up roller and the fifth roller in the five-roll calender is 1.05~1.3:1.

[0033] Therefore, the present invention has the following beneficial effects: (1) By using polyester plasticizer and powder modifier in combination, the present invention forms a dual insurance mechanism of “source substitution + adsorption anchoring”, which ensures that the adhesion between the adhesive layer and the film can always be greater than the adhesion between the adhesive layer and the substrate throughout the entire product life cycle, thereby effectively ensuring that the adhesive layer is completely separated from the substrate when peeling off the PVC wafer protective film, thus avoiding residual adhesive on the wafer surface. (2) The present invention introduces TPU elastomer and rigid powder modifier to form a “soft-hard” synergistic reinforcement system, so that the prepared PVC wafer protective film can “overcome hardness with softness” and “hard but not brittle” when punctured, showing puncture resistance far exceeding that of conventional formulations. (3) This invention designs a multi-stage precise plasticization control system to synergistically regulate the degree of plasticization of PVC, so that the product achieves the best balance between under-plasticization and over-plasticization. It effectively avoids problems such as molecular chain degradation, material embrittlement, puncture deformation and decreased elongation at break caused by over-plasticization, and at the same time avoids the phenomenon of uneven dispersion of TPU and inorganic powder modifier. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0035] Example 1 This embodiment provides a PVC wafer protective film and its preparation method.

[0036] A PVC wafer protective film, comprising, by weight: 100 parts PVC resin, 44 parts polyester plasticizer, 100 parts thermoplastic polyurethane elastomer (TPU), 5 parts powder modifier, 5.5 parts stabilizer, 8 parts impact modifier, 1.5 parts processing aid, 0.5 parts antioxidant, and 0.5 parts colorant.

[0037] The polyester plasticizer is adipic acid polyester with a molecular weight of 6000; the thermoplastic polyurethane elastomer (TPU) is a polyester-type TPU with a hardness of 85 A; and the powder modifier is fumed silica with a specific surface area of ​​200 m². 2 / g; the degree of polymerization of PVC resin is 1300; the stabilizer is barium zinc stabilizer UBZ 6301; the impact modifier is MBS resin; the processing aid is PA-40; the antioxidant is antioxidant 1010; the colorant is a combination of β-stabilized phthalocyanine blue pigment and 2,9-dimethylquinacridone.

[0038] A method for preparing a PVC wafer protective film as described above includes the following steps: S1: Dry the thermoplastic polyurethane elastomer (TPU) at 95 °C for 4 h; S2: Weigh the raw materials according to the PVC wafer protective film formula, add them to a high-speed mixer, stir, and then cool to room temperature to obtain a premix. S3: The premix obtained in step S2 is passed through an internal mixer for plasticization, a two-roll mill for secondary plasticization, and a filter for filtration to obtain a compressed material; The plasticizing temperature of the internal mixer is 165 ℃, the secondary plasticizing temperature of the two-roll open mill is 160 ℃, and the filter mesh size is 150 mesh. S4: The material is calendered into a PVC film by a five-roll calender and then taken out by a take-up roller and embossed by an embossing roller; The temperature control of each roll in the five-roll calender during the calendering process is as follows: The temperature of the first roller is 160 ℃, the temperature of the second roller is 166 ℃, the temperature of the third roller is 168 ℃, the temperature of the fourth roller is 167 ℃, and the temperature of the fifth roller is 165 ℃. The speed settings for each roll of the five-roll calender are as follows: The speed of the first roller is 7 m / min, the speed of the second roller is 17 m / min, the speed of the third roller is 24 m / min, the speed of the fourth roller is 29 m / min, and the speed of the fifth roller is 35 m / min; After being drawn out by the take-up roller, the calendered PVC film enters the embossing device for embossing. The embossing roller is a medium-gloss roller, the temperature of the embossing roller is 65 ℃, and the embossing pressure is set to 50 N. The rubber roller that is bonded to the embossing roller has a mesh size of 600 and a temperature of 15 ℃. The stretch ratio between the take-up roller and the 5th roller in the five-roll calender is 1.17:1. S5: Cool, trim, and roll up to obtain a PVC wafer protective film.

[0039] Example 2 The difference between this embodiment and Embodiment 1 is that: A PVC wafer protective film, wherein the degree of polymerization of the PVC resin is 1800; and the molecular weight of the polyester plasticizer is 3000. Everything else is the same as in Example 1.

[0040] Example 3 The difference between this embodiment and Embodiment 1 is that: A PVC wafer protective film, wherein the amount of TPU added is 60 parts. Everything else is the same as in Example 1.

[0041] Example 4 The difference between this embodiment and Embodiment 1 is that: A PVC wafer protective film, wherein the amount of TPU added is 140 parts. Everything else is the same as in Example 1.

[0042] Example 5 The difference between this embodiment and Embodiment 1 is that: A PVC wafer protective film, wherein the amount of powder modifier added is 10 parts. Everything else is the same as in Example 1.

[0043] Example 6 The difference between this embodiment and Embodiment 1 is that: A PVC wafer protective film, wherein the powder modifier is zeolite. Everything else is the same as in Example 1.

[0044] Example 7 The difference between this embodiment and Embodiment 1 is that: A PVC wafer protective film comprises 30 parts polyester plasticizer, 3 parts powder modifier, 4 parts stabilizer, 5 parts impact modifier, 1.5 parts processing aid, 0.5 parts antioxidant, and 0.2 parts colorant. The polyester plasticizer is adipic acid polyester with a molecular weight of 1500; the TPU hardness is 90 A; and the powder modifier is hydrotalcite with a specific surface area of ​​200 m² / g. 2 / g; The degree of polymerization of PVC resin is 1500.

[0045] A method for preparing a PVC wafer protective film as described above, wherein in step S1, TPU is dried at 80 ℃ for 6 h; in step S3, the plasticizing temperature of the internal mixer is 175 ℃, the secondary plasticizing temperature of the two-roll mill is 155 ℃, and the filter mesh size is 120 mesh; in step S4, the temperature control of each roll of the five-roll calender during the calendering process is as follows: The temperature of the first roller is 155 ℃, the temperature of the second roller is 160 ℃, the temperature of the third roller is 163 ℃, the temperature of the fourth roller is 162 ℃, and the temperature of the fifth roller is 160 ℃. The speed settings for each roll of the five-roll calender are as follows: The speed of the first roller is 3 m / min, the speed of the second roller is 13 m / min, the speed of the third roller is 20 m / min, the speed of the fourth roller is 25 m / min, and the speed of the fifth roller is 33 m / min; The embossing roller is a medium-gloss roller, the temperature of the embossing roller is 50 ℃, and the embossing pressure is set to 40 N; the rubber roller has a mesh size of 400 and a temperature of 15 ℃; the stretch ratio between the take-up roller and the 5th roller in the five-roll calender is 1.05:1. Everything else is the same as in Example 1.

[0046] Example 8 The difference between this embodiment and Embodiment 1 is that: A PVC wafer protective film comprises 60 parts polyester plasticizer, 7 parts powder modifier, 8 parts stabilizer, 15 parts impact modifier, 3 parts processing aid, 1 part antioxidant, and 1 part colorant. The polyester plasticizer is adipic acid polyester with a molecular weight of 4000; the TPU hardness is 95 A; and the powder modifier is fumed silica with a specific surface area of ​​250 m². 2 / g; The degree of polymerization of PVC resin is 1700.

[0047] A method for preparing a PVC wafer protective film as described above, wherein in step S1, TPU is dried at 100 ℃ for 8 h; in step S3, the plasticizing temperature of the internal mixer is 185 ℃, the secondary plasticizing temperature of the two-roll mill is 165 ℃, and the filter mesh size is 200 mesh; in step S4, the temperature control of each roll of the five-roll calender during the calendering process is as follows: The temperature of the first roller is 165 ℃, the temperature of the second roller is 170 ℃, the temperature of the third roller is 173 ℃, the temperature of the fourth roller is 172 ℃, and the temperature of the fifth roller is 170 ℃. The speed settings for each roll of the five-roll calender are as follows: The speed of the first roller is 10 m / min, the speed of the second roller is 21 m / min, the speed of the third roller is 28 m / min, the speed of the fourth roller is 33 m / min, and the speed of the fifth roller is 40 m / min; The embossing roller is a medium-gloss roller, the temperature of the embossing roller is 70 ℃, and the embossing pressure is set to 70 N; the mesh size of the rubber roller is 700 mesh, and the temperature of the rubber roller is 35 ℃; the stretch ratio between the take-up roller and the 5th roller in the five-roll calender is 1.3:1. Everything else is the same as in Example 1.

[0048] Comparative Example 1 The difference between this comparative example and Example 1 is as follows: A method for preparing a PVC wafer protective film, wherein the temperature control of each roll of the five-roll calender during the calendering process in step S4 is as follows: The temperature of the first roller is 150 ℃, the temperature of the second roller is 150 ℃, the temperature of the third roller is 156 ℃, the temperature of the fourth roller is 160 ℃, and the temperature of the fifth roller is 155 ℃; The speed settings for each roll of the five-roll calender are as follows: The speed of the first roller is 10 m / min, the speed of the second roller is 22 m / min, the speed of the third roller is 26 m / min, the speed of the fourth roller is 29 m / min, and the speed of the fifth roller is 37 m / min; The temperature of the rubber roller is 20 °C; the stretch ratio between the take-up roller and the embossing roller is 1.2:1. Everything else is the same as in Example 1.

[0049] Comparative Example 2 The difference between this comparative example and Example 1 is as follows: A method for preparing a PVC wafer protective film, wherein the temperature control of each roll of the five-roll calender during the calendering process in step S4 is as follows: The temperature of the first roller is 178 ℃, the temperature of the second roller is 186 ℃, the temperature of the third roller is 188 ℃, the temperature of the fourth roller is 178 ℃, and the temperature of the fifth roller is 175 ℃. The speed settings for each roll of the five-roll calender are as follows: The speed of the first roller is 10 m / min, the speed of the second roller is 22 m / min, the speed of the third roller is 26 m / min, the speed of the fourth roller is 29 m / min, and the speed of the fifth roller is 37 m / min; The temperature of the rubber roller is 20 °C; the stretch ratio between the take-up roller and the embossing roller is 1.2:1. Everything else is the same as in Example 1.

[0050] Comparative Example 3 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, wherein no TPU, powder modifier, or antioxidant is added. Everything else is the same as in Example 1.

[0051] A method for preparing a PVC wafer protective film as described above, wherein, in step S3, the secondary plasticizing temperature of the two-roll mill is 175 ℃; and in step S4, the temperature control of each roll of the five-roll calender during the calendering process is as follows: The temperature of the first roller is 175 ℃, the temperature of the second roller is 188 ℃, the temperature of the third roller is 188 ℃, the temperature of the fourth roller is 178 ℃, and the temperature of the fifth roller is 165 ℃. The speed settings for each roll of the five-roll calender are as follows: The speed of the first roller is 10 m / min, the speed of the second roller is 22 m / min, the speed of the third roller is 26 m / min, the speed of the fourth roller is 29 m / min, and the speed of the fifth roller is 37 m / min; The temperature of the rubber roller is 20 °C; the stretch ratio between the take-up roller and the embossing roller is 1.2:1. Everything else is the same as in Example 1.

[0052] Comparative Example 4 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, wherein no TPU or antioxidant is added; and the polyester plasticizer (polyester adipate) is replaced with a plasticizer (dioctyl terephthalate). Everything else is the same as in Example 1.

[0053] Comparative Example 5 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, wherein no powder modifier is added; the amount of TPU added is 30 parts. Everything else is the same as in Example 1.

[0054] Comparative Example 6 The difference between this comparative example and Example 1 is as follows: A method for preparing a PVC wafer protective film, wherein the secondary plasticizing temperature of the two-roll mill in step S3 is 140°C. All other steps are the same as in Example 1.

[0055] Comparative Example 7 The difference between this comparative example and Example 1 is as follows: A method for preparing a PVC wafer protective film, wherein the secondary plasticizing temperature of the two-roll mill in step S3 is 170°C. All other steps are the same as in Example 1.

[0056] Comparative Example 8 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, wherein the degree of polymerization of the PVC resin is 1000. Everything else is the same as in Example 1.

[0057] Comparative Example 9 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, wherein the degree of polymerization of the PVC resin is 2000. Everything else is the same as in Example 1.

[0058] Comparative Example 10 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, wherein a plasticizer (dioctyl terephthalate) is used instead of a polyester plasticizer (polyester adipate). Everything else is the same as in Example 1.

[0059] Comparative Example 11 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, wherein the polyester plasticizer is polyester adipic acid with a molecular weight of 8000. Everything else is the same as in Example 1.

[0060] Comparative Example 12 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, comprising 25 parts of polyester plasticizer. Everything else is the same as in Example 1.

[0061] Comparative Example 13 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, comprising 65 parts of polyester plasticizer. Everything else is the same as in Example 1.

[0062] Comparative Example 14 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, wherein the TPU content is 55 parts. Everything else is the same as in Example 1.

[0063] Comparative Example 15 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, wherein the TPU content is 145 parts. Everything else is the same as in Example 1.

[0064] Comparative Example 16 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, wherein the powder modifier comprises 2 parts. Everything else is the same as in Example 1.

[0065] Comparative Example 17 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, wherein the powder modifier comprises 15 parts. Everything else is the same as in Example 1.

[0066] Comparative Example 18 The difference between this comparative example and Example 1 is as follows: A PVC wafer protective film, wherein the powder modifier is fumed silica, and the specific surface area of ​​the powder modifier is 50 m². 2 / g. Everything else is the same as in Example 1.

[0067] PVC wafer protective films were prepared according to the methods described in Examples 1-6 and Comparative Examples 1-18, respectively. The puncture deformation of the films was tested according to GB / T 37841-2019, "Test Method for Puncture Resistance of Plastic Films and Sheets". The testing methods for tensile strength and elongation at break were mainly based on the national standard (GB / T 1040.3-2006, "Determination of Tensile Properties of Plastics - Part 3: Test Conditions for Thin Plastics and Sheets"). The degree of plasticization was determined by titrating 1 mL of ethyl acetate onto a 10 mm × 10 mm film and recording the time it took for the PVC wafer protective film to begin swelling. The product performance test results are shown in Table 1 below.

[0068] Table 1: Product Performance Test Indicators Group Puncture deformation / mm Tensile strength / MPa Elongation at break / % Swelling time / s Example 1 4.5 32.09 292.94 55 Example 2 4.2 34.12 286.5 62 Example 3 3.2 28.92 296.89 40 Example 4 4 30.69 341.42 52 Example 5 3.8 33.42 272.81 60 Example 6 4.3 32.23 289.88 52 Comparative Example 1 3.2 23.45 167.88 25 Comparative Example 2 3.2 26..48 222.45 23 Comparative Example 3 2.2 22.64 229.09 25 Comparative Example 4 2.5 25.78 242.93 20 Comparative Example 5 3 21.86 210.51 33 Comparative Example 6 3.5 24.56 188.44 32 Comparative Example 7 2.9 24.51 180.65 21 Comparative Example 8 2.2 20.89 245.67 60 Comparative Example 9 2.8 34.20 182.70 35 Comparative Example 10 3.6 25.10 256.40 20 Comparative Example 11 3.3 29.78 208.33 35 Comparative Example 12 2.5 29.82 152.30 25 Comparative Example 13 4.1 18.52 315.80 60 Comparative Example 14 2.3 24.78 270.12 32 Comparative Example 15 3.4 25.67 350.10 40 Comparative Example 16 3.2 30.50 280.24 48 Comparative Example 17 3.2 23.45 203.12 35 Comparative Example 18 3.6 31.20 275.40 35

[0069] The puncture deformation (3.2 mm to 4.5 mm) of Examples 1-6 was increased by an average of 50% to 100% compared to that of Comparative Example 3 (2.2 mm), directly demonstrating the crucial role of TPU particles as an elastomer in the PVC matrix. Upon impact from a puncture needle, the uniformly dispersed TPU particles effectively induced and terminated numerous streaks and shear bands, absorbing impact energy through their large deformation, thus significantly delaying crack initiation and propagation. Therefore, the modified PVC wafer protective film can maintain greater deformation without being punctured, exhibiting excellent toughness. A comparison of Examples 1, 3, and 4 shows that the puncture deformation initially increases and then decreases with increasing TPU dosage, indicating the existence of an optimal TPU addition amount. Too little TPU results in insufficient toughening, while too much may lead to particle agglomeration, creating stress concentration points and consequently reducing performance.

[0070] The tensile strength (28.92-34.12 MPa) and elongation at break (272.81-341.42%) of Examples 1-6 were generally better than those of Comparative Examples 3-4 (21.86-25.78 MPa and 210.51-242.92%), indicating that TPU and powder modifier have a synergistic effect, ensuring that the products have good strength and elongation.

[0071] The degree of plasticization significantly affects mechanical properties and puncture resistance. Comparative Example 1 (swelling time 25 s) and Comparative Example 6 (swelling time 32 s): the processing temperature was too low, indicating insufficient plasticization. The PVC resin particles failed to melt fully, resulting in a loose and incomplete three-dimensional network structure, leading to poor mechanical properties, easy precipitation of polyester plasticizer, and residual adhesive problems in subsequent applications. Comparative Example 2 (swelling time 23 s) and Comparative Example 7 (swelling time 21 s): the processing temperature was too high, resulting in over-plasticization. This may cause partial polymer degradation and plasticizer volatilization, damaging the structural integrity and also leading to performance degradation. Example 1 (swelling time 55 s): the processing temperature was suitable, resulting in the optimal degree of plasticization. Under this ideal condition, TPU and inorganic powder modifiers can be well dispersed in a fully plasticized and homogeneous PVC matrix, forming a complete and stable three-dimensional network structure, reducing the precipitation of polyester plasticizer and other additives, and avoiding residual adhesive problems in subsequent applications.

[0072] Comparing Comparative Examples 8-9 with Example 1 shows that the degree of polymerization of PVC has an optimal window for material properties. If the polymerization degree is too low, the carbon molecular chains are short, the intermolecular forces are weak, the PVC matrix strength is insufficient, and the puncture resistance and mechanical properties are significantly reduced. If the polymerization degree is too high, although the strength is improved, the excessively long carbon molecular chains are difficult to fully extend and melt during processing, resulting in poor plasticization and a significant decrease in puncture resistance. Example 1 and Comparative Examples 10-11 reveal the important role of the molecular weight of the polyester plasticizer. Low molecular weight polyester plasticizers have short swelling times (20 s), and the small molecule plasticizers are mainly physically entangled with the PVC chains, resulting in weak bonding forces and easy migration and precipitation, leading to significant residual glue problems in subsequent applications. High molecular weight polyester plasticizers have high viscosity, reduced plasticizing efficiency, and difficulty in fully inserting into the PVC molecular chains during processing, resulting in poor processability, poor plasticizing performance, and a significant decrease in overall performance.

[0073] Examples 1 and Comparative Examples 12-13 explored the effect of plasticizer dosage on performance. It can be seen that insufficient plasticizer dosage prevents adequate insertion between PVC molecular chains, resulting in insufficient PVC plasticization, decreased material flexibility, and a significant decrease in puncture deformation and elongation. Excessive plasticizer dosage, while showing good puncture deformation and elongation, significantly reduces tensile strength. Furthermore, some of the excess plasticizer exists in a free state, increasing the risk of migration. Examples 1, 3, and 4, along with Comparative Examples 14-15, systematically compared the effect of TPU dosage. TPU acts as an elastic dispersed phase in this system, its core function being to induce and terminate crazes and absorb impact energy. Insufficient TPU addition prevents the formation of an effective "island structure" energy absorption network, leading to a downward trend in overall performance. High TPU dosage not only results in higher costs and poorer processability but also leads to a decrease in physical properties.

[0074] Examples 1 and Comparative Examples 16-18 explored the effects of powder modifiers. Powder modifiers with high specific surface area have a positive effect on anti-migration, anti-precipitation, and material reinforcement. Appropriate dosage of powder modifier can enhance matrix strength, effectively exert the adsorption "anchoring" effect of the powder modifier, and inhibit plasticizer migration. Insufficient powder modifier dosage results in low reinforcement; excessive powder modifier dosage not only disrupts the toughness network of the TPU / PVC continuous phase, leading to brittleness, but also easily causes agglomeration during processing, forming defects and reducing its physical properties. Furthermore, a small specific surface area of ​​the powder modifier reduces its adsorption reinforcement effect.

[0075] In summary, by adjusting the formulation and preparation process of the PVC wafer protective film, the present invention produces a PVC wafer protective film with good mechanical properties and high puncture deformation.

[0076] The above description is merely a detailed explanation of preferred embodiments and principles of the present invention. For those skilled in the art, there may be changes in specific implementation methods based on the ideas provided by the present invention, and these changes should also be considered within the scope of protection of the present invention.

Claims

1. A PVC wafer protective film, characterized in that, Includes the following components: PVC resin, polyester plasticizer, thermoplastic polyurethane elastomer and powder modifier; The polyester plasticizer has a molecular weight of 1500-6000, the thermoplastic polyurethane elastomer is polyester-type TPU with a hardness of 85-95 A, and the powder modifier has a specific surface area greater than 150 m². 2 / g.

2. The PVC wafer protective film according to claim 1, characterized in that, By weight, it includes the following components: 100 parts PVC resin, 30-60 parts polyester plasticizer, 60-140 parts thermoplastic polyurethane elastomer, and 3-10 parts powder modifier.

3. The PVC wafer protective film according to claim 2, characterized in that, By weight, it also includes: Stabilizer 4-8 parts, impact modifier 5-15 parts, processing aid 1-3 parts, antioxidant 0.2-1 parts.

4. A PVC wafer protective film according to claim 2 or 3, characterized in that, It also includes 0.2 to 1 part pigment by weight.

5. A PVC wafer protective film according to claim 1 or 2, characterized in that, The polyester plasticizer is adipic acid polyester.

6. A PVC wafer protective film according to claim 1 or 2, characterized in that, The powder modifier is any one or a combination of fumed silica, zeolite, and hydrotalcite.

7. The PVC wafer protective film according to claim 3, characterized in that, The stabilizer is a barium-zinc stabilizer; The impact modifier is a core-shell structured acrylate impact modifier; The processing aid is PA-40; The antioxidant is any one or a combination of antioxidant 1010, antioxidant 1035, and antioxidant 1135.

8. A PVC wafer protective film according to claim 4, characterized in that, The pigment is any one or a combination of β-stable phthalocyanine blue pigment, 2,9-dimethylquinacridone, and α-unstable phthalocyanine blue pigment.

9. A method for preparing the PVC wafer protective film according to claim 1, characterized in that, Includes the following steps: S1: Drying the thermoplastic polyurethane elastomer; S2: Weigh the raw materials according to the PVC wafer protective film formula, mix and stir, and cool to room temperature to obtain the premix; S3: The premix obtained in step S2 is subjected to plasticization in an internal mixer, secondary plasticization in a two-roll mill, and filtration in sequence to obtain compressed material; The plasticizing temperature of the internal mixer is 175~185 ℃, and the secondary plasticizing temperature of the two-roll open mill is 155~165 ℃. S4: The pressed material obtained in step S3 is calendered into a film using a five-roll calender, and then embossed. The temperature control of each roll during the calendering process is as follows: The temperature of the first roller is 155~165 ℃, the temperature of the second roller is 160~170 ℃, the temperature of the third roller is 163~173 ℃, the temperature of the fourth roller is 162~172 ℃, and the temperature of the fifth roller is 160~170 ℃. S5: Cool, trim, and roll up to obtain a PVC wafer protective film.

10. The method for preparing a PVC wafer protective film according to claim 9, characterized in that, The speed settings for each roll during the calendering process in step S4 are as follows: The speed of the first roller is 3~10 m / min, the speed of the second roller is 13~21 m / min, the speed of the third roller is 20~28 m / min, the speed of the fourth roller is 25~33 m / min, and the speed of the fifth roller is 33~40 m / min.